Flow instability in particle-bed nuclear reactors

NASA Technical Reports Server (NTRS)

Kerrebrock, Jack L.

1993-01-01

The particle-bed core offers mitigation of some of the problems of solid-core nuclear rocket reactors. Dividing the fuel elements into small spherical particles contained in a cylindrical bed through which the propellant flows radially, may reduce the thermal stress in the fuel elements, allowing higher propellant temperatures to be reached. The high temperature regions of the reactor are confined to the interior of cylindrical fuel assemblies, so most of the reactor can be relatively cool. This enables the use of structural and moderating materials which reduce the minimum critical size and mass of the reactor. One of the unresolved questions about this concept is whether the flow through the particle-bed will be well behaved, or will be subject to destructive flow instabilities. Most of the recent analyses of the stability of the particle-bed reactor have been extensions of the approach of Bussard and Delauer, where the bed is essentially treated as an array of parallel passages, so that the mass flow is continuous from inlet to outlet through any one passage. A more general three dimensional model of the bed is adopted, in which the fluid has mobility in three dimensions. Comparison of results of the earlier approach to the present one shows that the former does not accurately represent the stability at low Re. The more complete model presented should be capable of meeting this deficiency while accurately representing the effects of the cold and hot frits, and of heat conduction and radiation in the particle-bed. It can be extended to apply to the cylindrical geometry of particle-bed reactors without difficulty. From the exemplary calculations which were carried out, it can be concluded that a particle-bed without a cold frit would be subject to instability if operated at the high temperatures desired for nuclear rockets, and at power densities below about 4 megawatts per liter. Since the desired power density is about 40 megawatts per liter, it can be concluded that operation at design exit temperature but at reduced power could be hazardous for such a reactor. But the calculations also show that an appropriate cold frit could very likely cure the instability. More definite conclusions must await calculations for specific designs.

Pellet bed reactor for nuclear propelled vehicles: Part 2: Missions and vehicle integration trades

NASA Technical Reports Server (NTRS)

Haloulakos, V. E.

1991-01-01

Mission and vehicle integration tradeoffs involving the use of the pellet bed reactor (PBR) for nuclear powered vehicles is discussed, with much of the information being given in viewgraph form. Information is given on propellant tank geometries, shield weight requirements for conventional tank configurations, effective specific impulse, radiation mapping, radiation dose rate after shutdown, space transfer vehicle design data, a Mars mission summary, sample pellet bed nuclear orbit transfer vehicle mass breakdown, and payload fraction vs. velocity increment.

Hexagonal boron nitride catalyst in a fixed-bed reactor for exothermic propane oxidation dehydrogenation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Jinshu; Lin, Jinhan; Xu, Mingliang

Hexagonal boron nitride (h-BN) with high thermal conductivity is potentially an effective catalyst for highly exothermic propane oxidative dehydrogenation (ODH) reaction. Here, we report our experimental and theoretic studies of such a catalyst for propane ODH in a fixed-bed reactor. Based on the computational fluid dynamics calculation (CFD) results, the catalyst bed temperature increases by less than 1°C in the h-BN catalyst bed which is much smaller than that (8°C) in the VO x/γ-Al 2O 3 catalyst bed at a similar propane conversion (25%) using a micro-tubular reactor with a diameter of 6 mm. Even in an industrially relevant reactormore » with an inner diameter of 60 mm, a uniform temperature profile can still be maintained using the h-BN catalyst bed due to its excellent thermal conductivity as opposed to a temperature gradient of 47°C in the VO x/γ-Al 2O 3 catalyst bed. The results reported here provide useful information for potential application of h-BN catalyst in propane ODH.« less

Hexagonal boron nitride catalyst in a fixed-bed reactor for exothermic propane oxidation dehydrogenation

DOE PAGES

Tian, Jinshu; Lin, Jinhan; Xu, Mingliang; ...

2018-04-17

Hexagonal boron nitride (h-BN) with high thermal conductivity is potentially an effective catalyst for highly exothermic propane oxidative dehydrogenation (ODH) reaction. Here, we report our experimental and theoretic studies of such a catalyst for propane ODH in a fixed-bed reactor. Based on the computational fluid dynamics calculation (CFD) results, the catalyst bed temperature increases by less than 1°C in the h-BN catalyst bed which is much smaller than that (8°C) in the VO x/γ-Al 2O 3 catalyst bed at a similar propane conversion (25%) using a micro-tubular reactor with a diameter of 6 mm. Even in an industrially relevant reactormore » with an inner diameter of 60 mm, a uniform temperature profile can still be maintained using the h-BN catalyst bed due to its excellent thermal conductivity as opposed to a temperature gradient of 47°C in the VO x/γ-Al 2O 3 catalyst bed. The results reported here provide useful information for potential application of h-BN catalyst in propane ODH.« less

Packed fluidized bed blanket for fusion reactor

DOEpatents

Chi, John W. H.

1984-01-01

A packed fluidized bed blanket for a fusion reactor providing for efficient radiation absorption for energy recovery, efficient neutron absorption for nuclear transformations, ease of blanket removal, processing and replacement, and on-line fueling/refueling. The blanket of the reactor contains a bed of stationary particles during reactor operation, cooled by a radial flow of coolant. During fueling/refueling, an axial flow is introduced into the bed in stages at various axial locations to fluidize the bed. When desired, the fluidization flow can be used to remove particles from the blanket.

Annular core liquid-salt cooled reactor with multiple fuel and blanket zones

DOEpatents

Peterson, Per F.

2013-05-14

A liquid fluoride salt cooled, high temperature reactor having a reactor vessel with a pebble-bed reactor core. The reactor core comprises a pebble injection inlet located at a bottom end of the reactor core and a pebble defueling outlet located at a top end of the reactor core, an inner reflector, outer reflector, and an annular pebble-bed region disposed in between the inner reflector and outer reflector. The annular pebble-bed region comprises an annular channel configured for receiving pebble fuel at the pebble injection inlet, the pebble fuel comprising a combination of seed and blanket pebbles having a density lower than the coolant such that the pebbles have positive buoyancy and migrate upward in said annular pebble-bed region toward the defueling outlet. The annular pebble-bed region comprises alternating radial layers of seed pebbles and blanket pebbles.

Shielded fluid stream injector for particle bed reactor

DOEpatents

Notestein, John E.

1993-01-01

A shielded fluid-stream injector assembly is provided for particle bed reactors. The assembly includes a perforated pipe injector disposed across the particle bed region of the reactor and an inverted V-shaped shield placed over the pipe, overlapping it to prevent descending particles from coming into direct contact with the pipe. The pipe and shield are fixedly secured at one end to the reactor wall and slidably secured at the other end to compensate for thermal expansion. An axially extending housing aligned with the pipe and outside the reactor and an in-line reamer are provided for removing deposits from the inside of the pipe. The assembly enables fluid streams to be injected and distributed uniformly into the particle bed with minimized clogging of injector ports. The same design may also be used for extraction of fluid streams from particle bed reactors.

Investigation of internal elements impaction on particles circulation in a fluidized bed reactor

NASA Astrophysics Data System (ADS)

Solovev, S. A.; Soloveva, O. V.; Antipin, A. V.; Shamsutdinov, E. V.

2018-01-01

A numerical study of the fluidized bed apparatus in the presence of various internal elements is carried out. A chemical reaction for temperature-dependent processes with heat absorption is considered. The task of incoming heated catalyst granules to the reactor is investigated. The main emphasis is focused on the circulation flows of the catalyst particles, heating of the reactor, and the efficiency of the chemical reaction. The analysis of the impact of various design elements on the efficiency of the reactor is carried out. The influence of feeding heated catalyst device design on the effectiveness of whole reactor heating is educed. The influence of the presence of fine particles on the efficiency of the reaction for different reactor design features is also educed.

Design of a laboratory scale fluidized bed reactor

NASA Astrophysics Data System (ADS)

Wikström, E.; Andersson, P.; Marklund, S.

1998-04-01

The aim of this project was to construct a laboratory scale fluidized bed reactor that simulates the behavior of full scale municipal solid waste combustors. The design of this reactor is thoroughly described. The size of the laboratory scale fluidized bed reactor is 5 kW, which corresponds to a fuel-feeding rate of approximately 1 kg/h. The reactor system consists of four parts: a bed section, a freeboard section, a convector (postcombustion zone), and an air pollution control (APC) device system. The inside diameter of the reactor is 100 mm at the bed section and it widens to 200 mm in diameter in the freeboard section; the total height of the reactor is 1760 mm. The convector part consists of five identical sections; each section is 2700 mm long and has an inside diameter of 44.3 mm. The reactor is flexible regarding the placement and number of sampling ports. At the beginning of the first convector unit and at the end of each unit there are sampling ports for organic micropollutants (OMP). This makes it possible to study the composition of the flue gases at various residence times. Sampling ports for inorganic compounds and particulate matter are also placed in the convector section. All operating parameters, reactor temperatures, concentrations of CO, CO2, O2, SO2, NO, and NO2 are continuously measured and stored at selected intervals for further evaluation. These unique features enable full control over the fuel feed, air flows, and air distribution as well as over the temperature profile. Elaborate details are provided regarding the configuration of the fuel-feeding systems, the fluidized bed, the convector section, and the APC device. This laboratory reactor enables detailed studies of the formation mechanisms of OMP, such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), poly-chlorinated biphenyls (PCBs), and polychlorinated benzenes (PCBzs). With this system formation mechanisms of OMP occurring in both the combustion and postcombustion zones can be studied. Other advantages are memory effect minimization and the reduction of experimental costs compared to full scale combustors. Comparison of the combustion parameters and emission data from this 5 kW laboratory scale reactor with full scale combustors shows good agreement regarding emission levels and PCDD/PCDF congener patterns. This indicates that the important formation and degradation reactions of OMP in the reactor are the same formation mechanisms as in full scale combustors.

Adsorption of Streptococcus faecalis on diatomite carriers for use in biotransformations.

PubMed

Anderson, W A; Bay, P; Legge, R L; Moo-Young, M

1990-01-01

Adsorption of cells on particulate carriers is potentially one of the most cost-effective immobilization techniques available. Diatomite carriers, such as Celite, have desirable physical properties, are inexpensive, and are suitable for both mycelial and bacterial systems. This work investigated the use of diatomite carriers as a biocatalyst support in a packed-bed reactor where L-tyrosine was enzymatically decarboxylated using adsorbed, non-growing cells of Streptococcus faecalis. Composition of microbial adsorption on different Celite types, with mean pore sizes ranging from 0.55 to 22 microns, showed there was no significant difference in biomass loading capacity under the conditions used. Using Celite 560, biomass loadings in a packed-bed reactor varied from 10 to 30 g dm-3 of reactor volume, which compares favourably with other adsorption methods. When used to decarboxylate L-tyrosine, the reactor was found to have a half-life of 15-20 h. A combination of enzyme activity loss and slow leakage of biomass from the packed-bed reactor was responsible for the decline in conversion. Treatment of the S. faecalis cells with glutaraldehyde significantly reduced the enzyme activity loss and extended the reactor half-life to 65 h, but had little effect on the rate of cell leakage from the reactor. Further work on reduction of cell leakage rate seems necessary for evaluation of the system's practicality.

Neutron Fluence And DPA Rate Analysis In Pebble-Bed HTR Reactor Vessel Using MCNP

NASA Astrophysics Data System (ADS)

Hamzah, Amir; Suwoto; Rohanda, Anis; Adrial, Hery; Bakhri, Syaiful; Sunaryo, Geni Rina

2018-02-01

In the Pebble-bed HTR reactor, the distance between the core and the reactor vessel is very close and the media inside are carbon and He gas. Neutron moderation capability of graphite material is theoretically lower than that of water-moderated reactors. Thus, it is estimated much more the fast neutrons will reach the reactor vessel. The fast neutron collisions with the atoms in the reactor vessel will result in radiation damage and could be reducing the vessel life. The purpose of this study was to obtain the magnitude of neutron fluence in the Pebble-bed HTR reactor vessel. Neutron fluence calculations in the pebble-bed HTR reactor vessel were performed using the MCNP computer program. By determining the tally position, it can be calculated flux, spectrum and neutron fluence in the position of Pebble-bed HTR reactor vessel. The calculations results of total neutron flux and fast neutron flux in the reactor vessel of 1.82x108 n/cm2/s and 1.79x108 n/cm2/s respectively. The fast neutron fluence in the reactor vessel is 3.4x1017 n/cm2 for 60 years reactor operation. Radiation damage in stainless steel material caused by high-energy neutrons (> 1.0 MeV) will occur when it has reached the neutron flux level of 1.0x1024 n/cm2. The neutron fluence results show that there is no radiation damage in the Pebble-bed HTR reactor vessel, so it is predicted that it will be safe to operate at least for 60 years.

Synthesis of Geraniol Esters in a Continuous-Flow Packed-Bed Reactor of Immobilized Lipase: Optimization of Process Parameters and Kinetic Modeling.

PubMed

Salvi, Harshada M; Kamble, Manoj P; Yadav, Ganapati D

2018-02-01

With increasing demand for perfumes, flavors, beverages, and pharmaceuticals, the various associated industries are resorting to different approaches to enhance yields of desired compounds. The use of fixed-bed biocatalytic reactors in some of the processes for making fine chemicals will be of great value because the reaction times could be reduced substantially as well as high conversion and yields obtained. In the current study, a continuous-flow packed-bed reactor of immobilized Candida antarctica lipase B (Novozym 435) was employed for synthesis of various geraniol esters. Optimization of process parameters such as biocatalyst screening, effect of solvent, mole ratio, temperature and acyl donors was studied in a continuous-flow packed-bed reactor. Maximum conversion of ~ 87% of geranyl propionate was achieved in 15 min residence time at 70 °C using geraniol and propionic acid with a 1:1 mol ratio. Novozym 435 was found to be the most active and stable biocatalyst among all tested. Ternary complex mechanism with propionic acid inhibition was found to fit the data.

A Numerical Model for Trickle Bed Reactors

NASA Astrophysics Data System (ADS)

Propp, Richard M.; Colella, Phillip; Crutchfield, William Y.; Day, Marcus S.

2000-12-01

Trickle bed reactors are governed by equations of flow in porous media such as Darcy's law and the conservation of mass. Our numerical method for solving these equations is based on a total-velocity splitting, sequential formulation which leads to an implicit pressure equation and a semi-implicit mass conservation equation. We use high-resolution finite-difference methods to discretize these equations. Our solution scheme extends previous work in modeling porous media flows in two ways. First, we incorporate physical effects due to capillary pressure, a nonlinear inlet boundary condition, spatial porosity variations, and inertial effects on phase mobilities. In particular, capillary forces introduce a parabolic component into the recast evolution equation, and the inertial effects give rise to hyperbolic nonconvexity. Second, we introduce a modification of the slope-limiting algorithm to prevent our numerical method from producing spurious shocks. We present a numerical algorithm for accommodating these difficulties, show the algorithm is second-order accurate, and demonstrate its performance on a number of simplified problems relevant to trickle bed reactor modeling.

Mass-transfer limitations for immobilized enzyme-catalyzed kinetic resolution of racemate in a fixed-bed reactor.

PubMed

Xiu, G H; Jiang, L; Li, P

2001-07-05

A mathematical model has been developed for immobilized enzyme-catalyzed kinetic resolution of racemate in a fixed-bed reactor in which the enzyme-catalyzed reaction (the irreversible uni-uni competitive Michaelis-Menten kinetics is chosen as an example) was coupled with intraparticle diffusion, external mass transfer, and axial dispersion. The effects of mass-transfer limitations, competitive inhibition of substrates, deactivation on the enzyme effective enantioselectivity, and the optical purity and yield of the desired product are examined quantitatively over a wide range of parameters using the orthogonal collocation method. For a first-order reaction, an analytical solution is derived from the mathematical model for slab-, cylindrical-, and spherical-enzyme supports. Based on the analytical solution for the steady-state resolution process, a new concise formulation is presented to predict quantitatively the mass-transfer limitations on enzyme effective enantioselectivity and optical purity and yield of the desired product for a continuous steady-state kinetic resolution process in a fixed-bed reactor. Copyright 2001 John Wiley & Sons, Inc.

[Rapid startup and nitrogen removal characteristic of anaerobic ammonium oxidation reactor in packed bed biofilm reactor with suspended carrier].

PubMed

Chen, Sheng; Sun, De-zhi; Yu, Guang-lu

2010-03-01

Packed bed biofilm reactor with suspended carrier was used to cultivate ANAMMOX bacteria with sludge inoculums from WWTP secondary settler. The startup of ANAMMOX reactor was comparatively studied using high nitrogen loading method and low nitrogen loading method with aerobically biofilmed on the carrier, and the nitrogen removal characteristic was further investigated. The results showed that the reactor could be started up successfully within 90 days using low nitrogen loading method, the removal efficiencies of ammonium and nitrite were nearly 100% and the TN removal efficiencywas over 75% , however, the high nitrogen loading method was proved unsuccessfully for startup of ANAMMOX reactor probably because of the inhibition effect of high concentration of ammonium and nitrite. The pH value of effluent was slightly higher than the influent and the pH value can be used as an indicator for the process of ANAMMOX reaction. The packed bed ANAMMOX reactor with suspended carrier showed good characteristics of high nitrogen loading and high removal efficiency, 100% of removal efficiency could be achieved when the influent ammonium and nitrite concentration was lower than 800 mg/L.

Lagrangian Approach to Study Catalytic Fluidized Bed Reactors

NASA Astrophysics Data System (ADS)

Madi, Hossein; Hossein Madi Team; Marcelo Kaufman Rechulski Collaboration; Christian Ludwig Collaboration; Tilman Schildhauer Collaboration

2013-03-01

Lagrangian approach of fluidized bed reactors is a method, which simulates the movement of catalyst particles (caused by the fluidization) by changing the gas composition around them. Application of such an investigation is in the analysis of the state of catalysts and surface reactions under quasi-operando conditions. The hydrodynamics of catalyst particles within a fluidized bed reactor was studied to improve a Lagrangian approach. A fluidized bed methanation employed in the production of Synthetic Natural Gas from wood was chosen as the case study. The Lagrangian perspective was modified and improved to include different particle circulation patterns, which were investigated through this study. Experiments were designed to evaluate the concepts of the model. The results indicate that the setup is able to perform the designed experiments and a good agreement between the simulation and the experimental results were observed. It has been shown that fluidized bed reactors, as opposed to fixed beds, can be used to avoid the deactivation of the methanation catalyst due to carbon deposits. Carbon deposition on the catalysts tested with the Lagrangian approach was investigated by temperature programmed oxidation (TPO) analysis of ex-situ catalyst samples. This investigation was done to identify the effects of particles velocity and their circulation patterns on the amount and type of deposited carbon on the catalyst surface. Ecole Polytechnique Federale de Lausanne(EPFL), Paul Scherrer Institute (PSI)

Use of a biparticle fluidized-bed bioreactor for the continuous and simultaneous fermentation and purification of lactic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaufman, E. N.; Cooper, S. P.; Clement, S. L.

A continuous biparticle fluidized bed reactor is developed for the simultaneous fermentation and purification of lactic acid. In this processing scheme, bacteria are immobilized in gelatin beads and are fluidized in a columnar reactor. Solid particles with sorbent capacity for the product are introduced at the top of the reactor, and fall counter currently to the biocatalyst, effecting in situ removal of the inhibitory product, while also controlling reactor pH at optimal levels. Initial long-term fermentation trials using immobilized Lactobacillus delbreuckii have demonstrated a 12 fold increase in volumetric productivity during adsorbent addition as opposed to control fermentations in themore » same reactor. Unoptimized regeneration of the loaded sorbent has effected at least an 8 fold concentration of lactic acid, and a 68 fold enhancement in separation from glucose compared to original levels in the fermentation broth. The benefits of this reactor system as opposed to conventional batch fermentation are discussed in terms of productivity and process economics.« less

Use of a biparticle fluidized-bed bioreactor for the continuous and simultaneous fermentation and purification of lactic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaufman, E.N.; Cooper, S.P.; Clement, S.L.

1995-12-31

A continuous biparticle fluidized-bed reactor is developed for the simultaneous fermentation and purification of lactic acid. In this processing scheme, bacteria are immobilized in gelatin beads and are fluidized in a columnar reactor. Solid particles with sorbent capacity for the product are introduced at the top of the reactor, and fall counter currently to the biocatalyst, effecting in situ removal of the inhibitory product, while also controlling reactor pH at optimal levels. Initial long-term fermentation trials using immobilized Lactobacillus delbreuckii have demonstrated a 12-fold increase in volumetric productivity during absorbent addition as opposed to control fermentations in the same reactor.more » Unoptimized regeneration of the loaded sorbent has effected at least an eightfold concentration of lactic acid and a 68-fold enhancement in separation from glucose compared to original levels in the fermentation broth. The benefits of this reactor system as opposed to conventional batch fermentation are discussed in terms of productivity and process economics.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sai, P.M.S.; Ahmed, J.; Krishnaiah, K.

Activated carbon is produced from coconut shell char using steam or carbon dioxide as the reacting gas in a 100 mm diameter fluidized bed reactor. The effect of process parameters such as reaction time, fluidizing velocity, particle size, static bed height, temperature of activation, fluidizing medium, and solid raw material on activation is studied. The product is characterized by determination of iodine number and BET surface area. The product obtained in the fluidized bed reactor is much superior in quality to the activated carbons produced by conventional processes. Based on the experimental observations, the optimum values of process parameters aremore » identified.« less

Continuous biological waste gas treatment in stirred trickle-bed reactor with discontinuous removal of biomass.

PubMed

Laurenzis, A; Heits, H; Wübker, S; Heinze, U; Friedrich, C; Werner, U

1998-02-20

A new reactor for biological waste gas treatment was developed to eliminate continuous solvents from waste gases. A trickle-bed reactor was chosen with discontinuous movement of the packed bed and intermittent percolation. The reactor was operated with toluene as the solvent and an optimum average biomass concentration of between 5 and 30 kg dry cell weight per cubic meter packed bed (m3pb). This biomass concentration resulted in a high volumetric degradation rate. Reduction of surplus biomass by stirring and trickling caused a prolonged service life and prevented clogging of the trickle bed and a pressure drop increase. The pressure drop after biomass reduction was almost identical to the theoretical pressure drop as calculated for the irregular packed bed without biomass. The reduction in biomass and intermittent percolation of mineral medium resulted in high volumetric degradation rates of about 100 g of toluene m-3pb h-1 at a load of 150 g of toluene m-3pb h-1. Such a removal rate with a trickle-bed reactor was not reported before. Copyright 1998 John Wiley & Sons, Inc.

Effects of intermittent aeration periods on a structured-bed reactor continuously fed on the post-treatment of sewage anaerobic effluent.

PubMed

Silva, Bruno Garcia; Damianovic, Márcia Helena Rissato Zamariolli; Foresti, Eugenio

2018-04-20

This study assessed the simultaneous nitrification and denitrification processes and remaining organic matter removal from anaerobic reactor effluent treating wastewater in a single reactor. A structured-bed reactor, with polyurethane foam as support media, was subjected to intermittent aeration and effluent recirculation. Aerated/non-aerated periods varied in the range of 2/1-1/3 h. The chemical oxygen demand (COD) in the effluent remained between 26 and 42 mg L -1 throughout all the aeration conditions. Aeration periods of 1/2 h removed 80 and 26% of Total Kjeldahl Nitrogen and Total Nitrogen, respectively. A low solid production was observed during the 300 days of operation, resulting in a solid retention time of 139 days. The results indicate that the non-aerated periods generated alkalinity that favored nitrification, maintaining low COD concentrations in the effluent. The structured bed reactor presented a low solid production and effluent loss below 20 mgSSV L -1 , similar to concentrations obtained in secondary decanters.

Characterization of metal adsorption kinetic properties in batch and fixed-bed reactors.

PubMed

Chen, J Paul; Wang, Lin

2004-01-01

Copper adsorption kinetic properties in batch and fixed-bed reactors were studied in this paper. The isothermal adsorption experiments showed that the copper adsorption capacity of a granular activated carbon (Filtrasorb 200) increased when ionic strength was higher. The presence of EDTA diminished the adsorption. An intraparticle diffusion model and a fixed-bed model were successfully used to describe the batch kinetic and fixed-bed operation behaviors. The kinetics became faster when the solution pH was not controlled, implying that the surface precipitation caused some metal uptake. The external mass transfer coefficient, the diffusivity and the dispersion coefficient were obtained from the modeling. It was found that both external mass transfer and dispersion coefficients increased when the flow rate was higher. Finally effects of kinetic parameters on simulation of fixed-bed operation were conducted.

Experimental and Computational Study of Multiphase Flow Hydrodynamics in 2D Trickle Bed Reactors

NASA Astrophysics Data System (ADS)

Nadeem, H.; Ben Salem, I.; Kurnia, J. C.; Rabbani, S.; Shamim, T.; Sassi, M.

2014-12-01

Trickle bed reactors are largely used in the refining processes. Co-current heavy oil and hydrogen gas flow downward on catalytic particle bed. Fine particles in the heavy oil and/or soot formed by the exothermic catalytic reactions deposit on the bed and clog the flow channels. This work is funded by the refining company of Abu Dhabi and aims at mitigating pressure buildup due to fine deposition in the TBR. In this work, we focus on meso-scale experimental and computational investigations of the interplay between flow regimes and the various parameters that affect them. A 2D experimental apparatus has been built to investigate the flow regimes with an average pore diameter close to the values encountered in trickle beds. A parametric study is done for the development of flow regimes and the transition between them when the geometry and arrangement of the particles within the porous medium are varied. Liquid and gas flow velocities have also been varied to capture the different flow regimes. Real time images of the multiphase flow are captured using a high speed camera, which were then used to characterize the transition between the different flow regimes. A diffused light source was used behind the 2D Trickle Bed Reactor to enhance visualizations. Experimental data shows very good agreement with the published literature. The computational study focuses on the hydrodynamics of multiphase flow and to identify the flow regime developed inside TBRs using the ANSYS Fluent Software package. Multiphase flow inside TBRs is investigated using the "discrete particle" approach together with Volume of Fluid (VoF) multiphase flow modeling. The effect of the bed particle diameter, spacing, and arrangement are presented that may be used to provide guidelines for designing trickle bed reactors.

Method of shielding a liquid-metal-cooled reactor

DOEpatents

Sayre, Robert K.

1978-01-01

The primary heat transport system of a nuclear reactor -- particularly for a liquid-metal-cooled fast-breeder reactor -- is shielded and protected from leakage by establishing and maintaining a bed of a powdered oxide closely and completely surrounding all components thereof by passing a gas upwardly therethrough at such a rate as to slightly expand the bed to the extent that the components of the system are able to expand without damage and yet the particles of the bed remain close enough so that the bed acts as a guard vessel for the system. Preferably the gas contains 1 to 10% oxygen and the gas is passed upwardly through the bed at such a rate that the lower portion of the bed is a fixed bed while the upper portion is a fluidized bed, the line of demarcation therebetween being high enough that the fixed bed portion of the bed serves as guard vessel for the system.

Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

NASA Astrophysics Data System (ADS)

Hu, Jian; Jiang, Nan; Li, Jie; Shang, Kefeng; Lu, Na; Wu, Yan; Mizuno, Akira

2016-03-01

The discharge characteristics of the series surface/packed-bed discharge (SSPBD) reactor driven by bipolar pulse power were systemically investigated in this study. In order to evaluate the advantages of the SSPBD reactor, it was compared with traditional surface discharge (SD) reactor and packed-bed discharge (PBD) reactor in terms of the discharge voltage, discharge current, and ozone formation. The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors. The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis. It was found that the packed-bed discharge region (3.5 mg/L), rather than the surface discharge region (1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation. The optical emission spectroscopy analysis indicated that more intense peaks of the active species (e.g. N2 and OI) in the optical emission spectra were observed in the packed-bed region. supported by National Natural Science Foundation of China (No. 51177007), the Joint Funds of National Natural Science Foundation of China (No. U1462105), and Dalian University of Technology Fundamental Research Fund of China (No. DUT15RC(3)030)

Preliminary CFD study of Pebble Size and its Effect on Heat Transfer in a Pebble Bed Reactor

NASA Astrophysics Data System (ADS)

Jones, Andrew; Enriquez, Christian; Spangler, Julian; Yee, Tein; Park, Jungkyu; Farfan, Eduardo

2017-11-01

In pebble bed reactors, the typical pebble diameter used is 6cm, and within each pebble is are thousands of nuclear fuel kernels. However, efficiency of the reactor does not solely depend on the number of kernels of fuel within each graphite sphere, but also depends on the type and motion of the coolant within the voids between the spheres and the reactor itself. In this work a physical analysis of the pebble bed nuclear reactor's fluid dynamics is undertaken using Computational Fluid Dynamics software. The primary goal of this work is to observe the relationship between the different pebble diameters in an idealized alignment and the thermal transport efficiency of the reactor. The model constructed of our idealized argument will consist on stacked 8 pebble columns that fixed at the inlet on the reactor. Two different pebble sizes 4 cm and 6 cm will be studied and helium will be supplied as coolant with a fixed flow rate of 96 kg/s, also a fixed pebble surface temperatures will be used. Comparison will then be made to evaluate the efficiency of coolant to transport heat due to the varying sizes of the pebbles. Assistant Professor for the Department of Civil and Construction Engineering PhD.

Continuous production of lipase-catalyzed biodiesel in a packed-bed reactor: optimization and enzyme reuse study.

PubMed

Chen, Hsiao-Ching; Ju, Hen-Yi; Wu, Tsung-Ta; Liu, Yung-Chuan; Lee, Chih-Chen; Chang, Cheng; Chung, Yi-Lin; Shieh, Chwen-Jen

2011-01-01

An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

Numerical study of radiative heat transfer and effects of thermal boundary conditions on CLC fuel reactor

NASA Astrophysics Data System (ADS)

Ben-Mansour, R.; Li, H.; Habib, M. A.; Hossain, M. M.

2018-02-01

Global warming has become a worldwide concern due to its severe impacts and consequences on the climate system and ecosystem. As a promising technology proving good carbon capture ability with low-efficiency penalty, Chemical Looping Combustion technology has risen much interest. However, the radiative heat transfer was hardly studied, nor its effects were clearly declared. The present work provides a mathematical model for radiative heat transfer within fuel reactor of chemical looping combustion systems and conducts a numerical research on the effects of boundary conditions, solid particles reflectivity, particles size, and the operating temperature. The results indicate that radiative heat transfer has very limited impacts on the flow pattern. Meanwhile, the temperature variations in the static bed region (where solid particles are dense) brought by radiation are also insignificant. However, the effects of radiation on temperature profiles within free bed region (where solid particles are very sparse) are obvious, especially when convective-radiative (mixed) boundary condition is applied on fuel reactor walls. Smaller oxygen carrier particle size results in larger absorption & scattering coefficients. The consideration of radiative heat transfer within fuel reactor increases the temperature gradient within free bed region. On the other hand, the conversion performance of fuel is nearly not affected by radiation heat transfer within fuel reactor. However, the consideration of radiative heat transfer enhances the heat transfer between the gas phase and solid phase, especially when the operating temperature is low.

EMERGING TECHNOLOGY BULLETIN: SPOUTED BED REACTOR

EPA Science Inventory

The Spouted Bed Reactor (SBR) technology utilizes the unique attributes of the "spouting " fluidization regime, which can provide heat transfer rates comparable to traditional fluid beds, while providing robust circulation of highly heterogeneous solids, concurrent with very agg...

Effect of small-scale biomass gasification at the state of refractory lining the fixed bed reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janša, Jan, E-mail: jan.jansa@vsb.cz; Peer, Vaclav, E-mail: vaclav.peer@vsb.cz; Pavloková, Petra, E-mail: petra.pavlokova@vsb.cz

The article deals with the influence of biomass gasification on the condition of the refractory lining of a fixed bed reactor. The refractory lining of the gasifier is one part of the device, which significantly affects the operational reliability and durability. After removing the refractory lining of the gasifier from the experimental reactor, there was done an assessment how gasification of different kinds of biomass reflected on its condition in terms of the main factors affecting its life. Gasification of biomass is reflected on the lining, especially through sticking at the bottom of the reactor. Measures for prolonging the lifemore » of lining consist in the reduction of temperature in the reactor, in this case, in order to avoid ash fusion biomass which it is difficult for this type of gasifier.« less

METHOD FOR SENSING DEGREE OF FLUIDIZATION IN FLUIDIZED BED

DOEpatents

Levey, R.P. Jr.; Fowler, A.H.

1961-12-12

A method is given for detecting, indicating, and controlling the degree of fluidization in a fluid-bed reactor into which powdered material is fed. The method comprises admitting of gas into the reactor, inserting a springsupported rod into the powder bed of the reactor, exciting the rod to vibrate at its resonant frequency, deriving a signal responsive to the amplitude of vibi-ation of the rod and spring, the signal being directiy proportional to the rate of flow of the gas through the reactor, displaying the signal to provide an indication of the degree of fluidization within the reactor, and controlling the rate of gas flow into the reactor until said signal stabilizes at a constant value to provide substantially complete fluidization within the reactor. (AEC)

The application of moving bed biofilm reactor to denitrification process after trickling filters.

PubMed

Kopec, Lukasz; Drewnowski, Jakub; Kopec, Adam

2016-12-01

The paper presents research of a prototype moving bed biofilm reactor (MBBR). The device was used for the post-denitrification process and was installed at the end of a technological system consisting of a septic tank and two trickling filters. The concentrations of suspended biomass and biomass attached on the EvU Perl moving bed surface were determined. The impact of the external organic carbon concentration on the denitrification rate and efficiency of total nitrogen removal was also examined. The study showed that the greater part of the biomass was in the suspended form and only 6% of the total biomass was attached to the surface of the moving bed. Abrasion forces between carriers of the moving bed caused the fast stripping of attached microorganisms and formation of flocs. Thanks to immobilization of a small amount of biomass, the MBBR was less prone to leaching of the biomass and the occurrence of scum and swelling sludge. It was revealed that the maximum rate of denitrification was an average of 0.73 gN-NO 3 /gDM·d (DM: dry matter), and was achieved when the reactor was maintained in external organic carbon concentration exceeding 300 mgO 2 /dm 3 chemical oxygen demand. The reactor proved to be an effective device enabling the increase of total nitrogen removal from 53.5% to 86.0%.

Pressure regulator

DOEpatents

Ebeling, Jr., Robert W.; Weaver, Robert B.

1979-01-01

The pressure within a pressurized flow reactor operated under harsh environmental conditions is controlled by establishing and maintaining a fluidized bed of uniformly sized granular material of selected density by passing the gas from the reactor upwardly therethrough at a rate sufficient to fluidize the bed and varying the height of the bed by adding granular material thereto or removing granular material therefrom to adjust the backpressure on the flow reactor.

In-pile test of Li 2TiO 3 pebble bed with neutron pulse operation

NASA Astrophysics Data System (ADS)

Tsuchiya, K.; Nakamichi, M.; Kikukawa, A.; Nagao, Y.; Enoeda, M.; Osaki, T.; Ioki, K.; Kawamura, H.

2002-12-01

Lithium titanate (Li 2TiO 3) is one of the candidate materials as tritium breeder in the breeding blanket of fusion reactors, and it is necessary to show the tritium release behavior of Li 2TiO 3 pebble beds. Therefore, a blanket in-pile mockup was developed and in situ tritium release experiments with the Li 2TiO 3 pebble bed were carried out in the Japan Materials Testing Reactor. In this study, the relationship between tritium release behavior from Li 2TiO 3 pebble beds and effects of various parameters were evaluated. The ( R/ G) ratio of tritium release ( R) and tritium generation ( G) was saturated when the temperature at the outside edge of the Li 2TiO 3 pebble bed became 300 °C. The tritium release amount increased cycle by cycle and saturated after about 20 pulse operations.

Accumulation of radionuclides in bed sediments of the Columbia River between Hanford reactors and McNary Dam

USGS Publications Warehouse

Nelson, Jack L.; Haushild, W.L.

1970-01-01

Amounts of radionuclides from the Hanford reactors contained in bed sediments of the Columbia River were estimated by two methods: (1) from data on radionuclide concentration for the bed sediments between the reactors and McNary Dam, and (2) from data on radionuclide discharge for river stations at Pasco, Washington, and Umatilla, Oregon. Umatilla is 3.2 kilometers below McNary Dam. Accumulations of radionuclides in the Pasco to Umatilla reach estimated by the two methods agree within about 8%. In October 1965 approximately 16,000 curies of gamma emitting radionuclides were resident in bed sediments of the river between the Hanford reactors and McNary Dam. Concentrations and accumulations of chromium-51, zinc-65, cobalt-60, manganese-54, and scandium-46 generally are much higher near McNary Dam than they are in the vicinity of the reactors. These changes are caused by an increase downstream from the reactors in the proportion of the bed sediment that is fine grained and the proportions of the transported zinc, cobalt, manganese, and scandium radionuclides associated with sediment particles.

Cyclic process for producing methane in a tubular reactor with effective heat removal

DOEpatents

Frost, Albert C.; Yang, Chang-Lee

1986-01-01

Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

Trace metal distribution and control in the pilot-scale bubbling fluidized bed combustor equipped with the pulse-jet fabric filter, limestone injection, and the humidification reactor.

PubMed

Kouvo, Petri

2003-04-01

This work focused on trace metal behavior and removal in a fabric filter or in a humidification reactor during the cofiring of sawdust and refuse-derived fuels (RDFs) in a pilot-scale bubbling fluidized bed (BFB) boiler. Trace metal emissions measurements before and after the fabric filter revealed that removal efficiency in the fabric filter was in the range of 80-100%, and that the European Union (EU) Directive on Incineration of Waste restrictions for trace metal emissions are easily achieved even if addition of RDFs substantially increases the concentration of trace metals in fuel blends. Limestone injection enhanced the removal of As and Se but had no noticeable effect on the removal of other trace metals. Extensive formation of HgCl2 and condensation on fly ash particles during sawdust plus 40% RDF cofiring resulted in a 92% Hg removal efficiency in the fabric filter. Limestone injection had no effect on the Hg removal in the fabric filter but decreased the Hg removal in a humidification reactor from 40 to 28%. Results of the bed material and fly ash analysis suggested capture of Cu, Pb, Mn, Ni, and Zn in the bed material but also suggested that these metals may be released from the bed if the fuel characteristics or process conditions are changed.

Thermal Hydraulic Analysis of a Packed Bed Reactor Fuel Element

DTIC Science & Technology

1989-05-25

Engineer and Master of Science in Nuclear Engineering. ABSTRACT A model of the behavior of a packed bed nuclear reactor fuel element is developed . It...RECOMMENDATIONS FOR FURTHER INVESTIGATION .................... 150 APPENDIX A FUEL ELEMENT MODEL PROGRAM DESIGN AND OPERA- T IO N...follow describe the details of the packed bed reactor and then discuss the development of the mathematical representations of the fuel element. These are

NEUTRONIC REACTOR POWER PLANT

DOEpatents

Metcalf, H.E.

1962-12-25

This patent relates to a nuclear reactor power plant incorporating an air-cooled, beryllium oxide-moderated, pebble bed reactor. According to the invention means are provided for circulating a flow of air through tubes in the reactor to a turbine and for directing a sidestream of the circu1ating air through the pebble bed to remove fission products therefrom as well as assist in cooling the reactor. (AEC)

Investigation of the characteristics of a compact steam reformer integrated with a water-gas shift reactor

NASA Astrophysics Data System (ADS)

Seo, Yong-Seog; Seo, Dong-Joo; Seo, Yu-Taek; Yoon, Wang-Lai

The objective of this study is to investigate numerically a compact steam methane reforming (SMR) system integrated with a water-gas shift (WGS) reactor. Separate numerical models are established for the combustion part, SMR and WGS reaction bed. The concentration of species at the exits of the SMR and WGS bed, and the temperatures in the WGS bed are in good agreement with the measured data. Heat transfer to the catalyst beds and the catalytic reactions in the SMR and WGS catalyst bed are investigated as a function of the operation parameters. The conversion of methane at the exit of the SMR catalyst bed is calculated to be 87%, and the carbon monoxide concentration at the outlet of the WGS bed is estimated to be 0.45%. The effects of the cooling heat flux at the outside wall of the system and steam-to-carbon (S/C) ratio are also examined. As the cooling heat flux increases, both the methane conversion and carbon monoxide content are reduced in the SMR bed, and the carbon monoxide conversion is improved in the WGS bed. Both methane conversion and carbon dioxide reduction increase with increasing steam-to-carbon ratio.

Numerical investigation of flow and heat transfer in a novel configuration multi-tubular fixed bed reactor for propylene to acrolein process

NASA Astrophysics Data System (ADS)

Jiang, Bin; Hao, Li; Zhang, Luhong; Sun, Yongli; Xiao, Xiaoming

2015-01-01

In the present contribution, a numerical study of fluid flow and heat transfer performance in a pilot-scale multi-tubular fixed bed reactor for propylene to acrolein oxidation reaction is presented using computational fluid dynamics (CFD) method. Firstly, a two-dimensional CFD model is developed to simulate flow behaviors, catalytic oxidation reaction, heat and mass transfer adopting porous medium model on tube side to achieve the temperature distribution and investigate the effect of operation parameters on hot spot temperature. Secondly, based on the conclusions of tube-side, a novel configuration multi-tubular fixed-bed reactor comprising 790 tubes design with disk-and-doughnut baffles is proposed by comparing with segmental baffles reactor and their performance of fluid flow and heat transfer is analyzed to ensure the uniformity condition using molten salt as heat carrier medium on shell-side by three-dimensional CFD method. The results reveal that comprehensive performance of the reactor with disk-and-doughnut baffles is better than that of with segmental baffles. Finally, the effects of operating conditions to control the hot spots are investigated. The results show that the flow velocity range about 0.65 m/s is applicable and the co-current cooling system flow direction is better than counter-current flow to control the hottest temperature.

Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield.

PubMed

Araújo, Paulo Jardel P; Leite, Manuela Souza; Ravagnani, Teresa M Kakuta

2016-01-01

Styrene is an important monomer in the manufacture of thermoplastic. Most of it is produced by the catalytic dehydrogenation of ethylbenzene. In this process that depends on reversible reactions, the yield is usually limited by the establishment of thermodynamic equilibrium in the reactor. The styrene yield can be increased by using a hybrid process, with reaction and separation simultaneously. It is proposed using permselective composite membrane to remove hydrogen and thus suppress the reverse and secondary reactions. This paper describes the simulation of a dehydrogenation process carried out in a tubular fixed-bed reactor wrapped in a permselective composite membrane. A mathematical model was developed, incorporating the various mass transport mechanisms found in each of the membrane layers and in the catalytic fixed bed. The effects of the reactor feed conditions (temperature, steam-to-oil ratio, and the weight hourly space velocity), the fixed-bed geometry (length, diameter, and volume), and the membrane geometry (thickness of the layers) on the styrene yield were analyzed. These variables were used to determine experimental conditions that favour the production of styrene. The simulation showed that an increase of 40.98% in the styrene yield, compared to a conventional fixed-bed process, could be obtained by wrapping the reactor in a permselective composite membrane.

Feasibility Study of the Geotextile Waste Filtration Unit.

DTIC Science & Technology

2000-02-10

Treatment Module 3-32 Figure 3-20. THE SCHEMATIC OF THE MOVING BED BIOFILM REACTOR ( MBBR ) 3൪ Figure 4-1. The Original Distributed Concept for WFUs...Moving Bed Biofilm Reactor ( MBBR ) process appears to be one of the most feasible processes available to meet Force Provider liquid waste stream...Moving Bed Biofilm Reactor ( MBBR ) process was then examined.31 In this system, both activated sludge and fixed-film processes occur in a bioreactor

X-ray digital industrial radiography (DIR) for local liquid velocity (VLL) measurement in trickle bed reactors (TBRs): Validation of the technique

NASA Astrophysics Data System (ADS)

Mohd Salleh, Khairul Anuar; Rahman, Mohd Fitri Abdul; Lee, Hyoung Koo; Al Dahhan, Muthanna H.

2014-06-01

Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (VLL) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure the VLL within TBRs.

X-ray digital industrial radiography (DIR) for local liquid velocity (V(LL)) measurement in trickle bed reactors (TBRs): validation of the technique.

PubMed

Mohd Salleh, Khairul Anuar; Rahman, Mohd Fitri Abdul; Lee, Hyoung Koo; Al Dahhan, Muthanna H

2014-06-01

Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (V(LL)) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure the V(LL) within TBRs.

Factors affecting cleanup of exhaust gases from a pressurized, fluidized-bed coal combustor

NASA Technical Reports Server (NTRS)

Rollbuhler, R. J.; Kobak, J. A.

1980-01-01

The cleanup of effluent gases from the fluidized-bed combustion of coal is examined. Testing conditions include the type and feed rate of the coal and the sulfur sorbent, the coal-sorbent ratio, the coal-combustion air ratio, the depth of the reactor fluidizing bed, and the technique used to physically remove fly ash from the reactor effluent gases. Tests reveal that the particulate loading matter in the effluent gases is a function not only of the reactor-bed surface gas velocity, but also of the type of coal being burnt and the time the bed is operating. At least 95 percent of the fly ash particules in the effluent gas are removed by using a gas-solids separator under controlled operating conditions. Gaseous pollutants in the effluent (nitrogen and sulfur oxides) are held within the proposed Federal limits by controlling the reactor operating conditions and the type and quantity of sorbent material.

Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

DOEpatents

Gabor, John D.; Cassulo, John C.; Pedersen, Dean R.; Baker, Jr., Louis

1986-01-01

The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and be discharged from the reactor core. The invention provides a porous bed or sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

DOEpatents

Gabor, John D.; Cassulo, John C.; Pedersen, Dean R.; Baker Jr., Louis

1986-07-01

The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and be discharged from the reactor core. The invention provides a porous bed or sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

DOEpatents

Gabor, J.D.; Cassulo, J.C.; Pedersen, D.R.; Baker, L. Jr.

The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and can be discharged from the reactor core. The invention provides a porous bed of sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

Conversion of NO with a catalytic packed-bed dielectric barrier discharge reactor

NASA Astrophysics Data System (ADS)

Xu, CAO; Weixuan, ZHAO; Renxi, ZHANG; Huiqi, HOU; Shanping, CHEN; Ruina, ZHANG

2017-11-01

This paper discusses the conversion of nitric oxide (NO) with a low-temperature plasma induced by a catalytic packed-bed dielectric barrier discharge (DBD) reactor. Alumina oxide (Al2O3), glass (SiO2) and zirconium oxide (ZrO2), three different spherical packed materials of the same size, were each present in the DBD reactor. The NO conversion under varying input voltage and specific energy density, and the effects of catalysts (titanium dioxide (TiO2) and manganese oxide (MnO x ) coated on Al2O3) on NO conversion were investigated. The experimental results showed that NO conversion was greatly enhanced in the presence of packed materials in the reactor, and the catalytic packed bed of MnO x /Al2O3 showed better performance than that of TiO2/Al2O3. The surface and crystal structures of the materials and catalysts were characterized through scanning electron microscopy analysis. The final products were clearly observed by a Fourier transform infrared spectrometer and provided a better understanding of NO conversion.

[Feasibility of treatment of landfill leachates by external loop three phase fluidized bed-constructed wetland system].

PubMed

Zhang, Jin-Sheng; Yuan, Xing-Zhong; Zeng, Guang-Ming; Dong, Bei-Bei; Liang, Yun-Shan

2009-11-01

In this study, the system composed with the external loop fluidized bed reactor and constructed wetland was used to treat the landfill leachate. The change of water quality for the landfill leachate treated by this system was investigated. The experimental results indicated that the COD and NH4(+) -N of the influent reduced from 4000 mg x L(-1) and 300 mg x L(-1) to 1 500 mg x L(-1) and 150 mg x L(-1) after the external loop three phase fluidized bed reactor and steady at 200 mg x L(-1) and 10 mg x L(-1) behind treated by the constructed wetland. The heavy metals of Cd, Zn, Pb were also reduced for treatment by external loop three phase fluidized bed reactor. They were steady at 0.01 mg x L(-1), 0.5 mg x L(-1), 0.1 mg x L(-1) from 0.12 mg x L(-1), 3.0 mg x L(-1), 1.4 mg x L(-1) because of the constructed wetland. We also compared the different plants for the efficiency, the results showed that whatever plants, there was little effects on the efficiency of the COD and NH4(+) -N, but the effect of heavy metal was markedness.

Biodegradation of Methyl Tertiary Butyl Ether (MTBE) by a Microbial Consortium in a Continuous Up-Flow Packed-Bed Biofilm Reactor: Kinetic Study, Metabolite Identification and Toxicity Bioassays

PubMed Central

Alfonso-Gordillo, Guadalupe; Flores-Ortiz, César Mateo; Morales-Barrera, Liliana

2016-01-01

This study investigated the aerobic biodegradation of methyl tertiary-butyl ether (MTBE) by a microbial consortium in a continuous up-flow packed-bed biofilm reactor using tezontle stone particles as a supporting material for the biofilm. Although MTBE is toxic for microbial communities, the microbial consortium used here was able to resist MTBE loading rates up to 128.3 mg L-1 h-1, with removal efficiencies of MTBE and chemical oxygen demand (COD) higher than 90%. A linear relationship was observed between the MTBE loading rate and the MTBE removal rate, as well as between the COD loading rate and the COD removal rate, within the interval of MTBE loading rates from 11.98 to 183.71 mg L-1 h-1. The metabolic intermediate tertiary butyl alcohol (TBA) was not detected in the effluent during all reactor runs, and the intermediate 2-hydroxy butyric acid (2-HIBA) was only detected at MTBE loading rates higher than 128.3 mg L-1 h-1. The results of toxicity bioassays with organisms from two different trophic levels revealed that the toxicity of the influent was significantly reduced after treatment in the packed-bed reactor. The packed-bed reactor system used in this study was highly effective for the continuous biodegradation of MTBE and is therefore a promising alternative for detoxifying MTBE-laden wastewater and groundwater. PMID:27907122

Biodegradation of Methyl Tertiary Butyl Ether (MTBE) by a Microbial Consortium in a Continuous Up-Flow Packed-Bed Biofilm Reactor: Kinetic Study, Metabolite Identification and Toxicity Bioassays.

PubMed

Alfonso-Gordillo, Guadalupe; Flores-Ortiz, César Mateo; Morales-Barrera, Liliana; Cristiani-Urbina, Eliseo

2016-01-01

This study investigated the aerobic biodegradation of methyl tertiary-butyl ether (MTBE) by a microbial consortium in a continuous up-flow packed-bed biofilm reactor using tezontle stone particles as a supporting material for the biofilm. Although MTBE is toxic for microbial communities, the microbial consortium used here was able to resist MTBE loading rates up to 128.3 mg L-1 h-1, with removal efficiencies of MTBE and chemical oxygen demand (COD) higher than 90%. A linear relationship was observed between the MTBE loading rate and the MTBE removal rate, as well as between the COD loading rate and the COD removal rate, within the interval of MTBE loading rates from 11.98 to 183.71 mg L-1 h-1. The metabolic intermediate tertiary butyl alcohol (TBA) was not detected in the effluent during all reactor runs, and the intermediate 2-hydroxy butyric acid (2-HIBA) was only detected at MTBE loading rates higher than 128.3 mg L-1 h-1. The results of toxicity bioassays with organisms from two different trophic levels revealed that the toxicity of the influent was significantly reduced after treatment in the packed-bed reactor. The packed-bed reactor system used in this study was highly effective for the continuous biodegradation of MTBE and is therefore a promising alternative for detoxifying MTBE-laden wastewater and groundwater.

Media arrangement impacts cell growth in anaerobic fixed-bed reactors treating sugarcane vinasse: Structured vs. randomic biomass immobilization.

PubMed

de Aquino, Samuel; Fuess, Lucas Tadeu; Pires, Eduardo Cleto

2017-07-01

This study reports on the application of an innovative structured-bed reactor (FVR) as an alternative to conventional packed-bed reactors (PBRs) to treat high-strength solid-rich wastewaters. Using the FVR prevents solids from accumulating within the fixed-bed, while maintaining the advantages of the biomass immobilization. The long-term operation (330days) of a FVR and a PBR applied to sugarcane vinasse under increasing organic loads (2.4-18.0kgCODm -3 day -1 ) was assessed, focusing on the impacts of the different media arrangements over the production and retention of biomass. Much higher organic matter degradation rates, as well as long-term operational stability and high conversion efficiencies (>80%) confirmed that the FVR performed better than the PBR. Despite the equivalent operating conditions, the biomass growth yield was different in both reactors, i.e., 0.095gVSSg -1 COD (FVR) and 0.066gVSSg -1 COD (PBR), indicating a clear control of the media arrangement over the biomass production in fixed-bed reactors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of shear stress on cell cultures and other reactor problems

NASA Technical Reports Server (NTRS)

Schleier, H.

1981-01-01

Anchorage dependent cell cultures in fluidized beds are tested. Feasibility calculations indicate the allowed parameters and estimate the shear stresses therein. In addition, the diffusion equation with first order reaction is solved for the spherical shell (double bubble) reactor with various constraints.

Integrated detoxification methodology of hazardous phenolic wastewaters in environmentally based trickle-bed reactors: Experimental investigation and CFD simulation.

PubMed

Lopes, Rodrigo J G; Almeida, Teresa S A; Quinta-Ferreira, Rosa M

2011-05-15

Centralized environmental regulations require the use of efficient detoxification technologies for the secure disposal of hazardous wastewaters. Guided by federal directives, existing plants need reengineering activities and careful analysis to improve their overall effectiveness and to become environmentally friendly. Here, we illustrate the application of an integrated methodology which encompasses the experimental investigation of catalytic wet air oxidation and CFD simulation of trickle-bed reactors. As long as trickle-bed reactors are determined by the flow environment coupled with chemical kinetics, first, on the optimization of prominent numerical solution parameters, the CFD model was validated with experimental data taken from a trickle bed pilot plant specifically designed for the catalytic wet oxidation of phenolic wastewaters. Second, several experimental and computational runs were carried out under unsteady-state operation to evaluate the dynamic performance addressing the TOC concentration and temperature profiles. CFD computations of total organic carbon conversion were found to agree better with experimental data at lower temperatures. Finally, the comparison of test data with simulation results demonstrated that this integrated framework was able to describe the mineralization of organic matter in trickle beds and the validated consequence model can be exploited to promote cleaner remediation technologies of contaminated waters. Copyright © 2011 Elsevier B.V. All rights reserved.

Treatment of screened dairy manure by upflow anaerobic fixed bed reactors packed with waste tyre rubber and a combination of waste tyre rubber and zeolite: effect of the hydraulic retention time.

PubMed

Umaña, Oscar; Nikolaeva, Svetlana; Sánchez, Enrique; Borja, Rafael; Raposo, Francisco

2008-10-01

Two laboratory-scale anaerobic fixed bed reactors were evaluated while treating dairy manure at upflow mode and semicontinuous feeding. One reactor was packed with a combination of waste tyre rubber and zeolite (R1) while the other had only waste tyre rubber as a microorganism immobilization support (R2). Effluent quality improved when the hydraulic retention time (HRT) increased from 1.0 to 5.5 days. Higher COD, BOD5, total and volatile solids removal efficiencies were always achieved in the reactor R1. No clogging was observed during the operation period. Methane yield was also a function of the HRT and of the type of support used, and was 12.5% and 40% higher in reactor R1 than in R2 for HRTs of 5.5 and 1.0 days, respectively. The results obtained demonstrated that this type of reactor is capable of operating with dairy manure at a HRT 5 times lower than that used in a conventional reactor.

Trickle-bed root culture bioreactor design and scale-up: growth, fluid-dynamics, and oxygen mass transfer.

PubMed

Ramakrishnan, Divakar; Curtis, Wayne R

2004-10-20

Trickle-bed root culture reactors are shown to achieve tissue concentrations as high as 36 g DW/L (752 g FW/L) at a scale of 14 L. Root growth rate in a 1.6-L reactor configuration with improved operational conditions is shown to be indistinguishable from the laboratory-scale benchmark, the shaker flask (mu=0.33 day(-1)). These results demonstrate that trickle-bed reactor systems can sustain tissue concentrations, growth rates and volumetric biomass productivities substantially higher than other reported bioreactor configurations. Mass transfer and fluid dynamics are characterized in trickle-bed root reactors to identify appropriate operating conditions and scale-up criteria. Root tissue respiration goes through a minimum with increasing liquid flow, which is qualitatively consistent with traditional trickle-bed performance. However, liquid hold-up is much higher than traditional trickle-beds and alternative correlations based on liquid hold-up per unit tissue mass are required to account for large changes in biomass volume fraction. Bioreactor characterization is sufficient to carry out preliminary design calculations that indicate scale-up feasibility to at least 10,000 liters.

Heat pump apparatus

DOEpatents

Nelson, Paul A.; Horowitz, Jeffrey S.

1983-01-01

A heat pump apparatus including a compact arrangement of individual tubular reactors containing hydride-dehydride beds in opposite end sections, each pair of beds in each reactor being operable by sequential and coordinated treatment with a plurality of heat transfer fluids in a plurality of processing stages, and first and second valves located adjacent the reactor end sections with rotatable members having multiple ports and associated portions for separating the hydride beds at each of the end sections into groups and for simultaneously directing a plurality of heat transfer fluids to the different groups. As heat is being generated by a group of beds, others are being regenerated so that heat is continuously available for space heating. As each of the processing stages is completed for a hydride bed or group of beds, each valve member is rotated causing the heat transfer fluid for the heat processing stage to be directed to that bed or group of beds. Each of the end sections are arranged to form a closed perimeter and the valve member may be rotated repeatedly about the perimeter to provide a continuous operation. Both valves are driven by a common motor to provide a coordinated treatment of beds in the same reactors. The heat pump apparatus is particularly suitable for the utilization of thermal energy supplied by solar collectors and concentrators but may be used with any source of heat, including a source of low-grade heat.

Solar photocatalytic disinfection with immobilised TiO(2) at pilot-plant scale.

PubMed

Sordo, Carlos; Van Grieken, Rafael; Marugán, Javier; Fernández-Ibáñez, Pilar

2010-01-01

The photocatalytic disinfection efficiency has been investigated for two immobilized TiO(2) catalytic systems (wall reactor and fixed-bed reactor) in a solar pilot plant. Their performances have been compared with the use of a slurry reactor and the solar disinfection without catalyst. The use of photocatalytic TiO(2) wall reactors does no show clear benefits over the solar disinfection process in the absence of catalyst. The reason is that the efficiency of the solar disinfection is so high that the presence of titania in the reactor wall reduces the global efficiency due to the competition for the absorption of photons. As expected, the maximum efficiency was shown by the slurry TiO(2) reactor, due to the optimum contact between bacteria and catalyst. However, it is noticeable that the use of the fixed-bed reactor leads to inactivation rate quite close to that of the slurry, requiring comparable accumulated solar energy of about 6 kJ L(-1) to achieve a 6-log decrease in the concentration of viable bacteria and allowing a total disinfection of the water (below the detection limit of 1 CFU mL(-1)). Not only the high titania surface area of this configuration is responsible for the bacteria inactivation but the important contribution of the mechanical stress has to be considered. The main advantage of the fixed-bed TiO(2) catalyst is the outstanding stability, without deactivation effects after ten reaction cycles, being readily applicable for continuous water treatment systems.

Material Control and Accounting Design Considerations for High-Temperature Gas Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trond Bjornard; John Hockert

The subject of this report is domestic safeguards and security by design (2SBD) for high-temperature gas reactors, focusing on material control and accountability (MC&A). The motivation for the report is to provide 2SBD support to the Next Generation Nuclear Plant (NGNP) project, which was launched by Congress in 2005. This introductory section will provide some background on the NGNP project and an overview of the 2SBD concept. The remaining chapters focus specifically on design aspects of the candidate high-temperature gas reactors (HTGRs) relevant to MC&A, Nuclear Regulatory Commission (NRC) requirements, and proposed MC&A approaches for the two major HTGR reactormore » types: pebble bed and prismatic. Of the prismatic type, two candidates are under consideration: (1) GA's GT-MHR (Gas Turbine-Modular Helium Reactor), and (2) the Modular High-Temperature Reactor (M-HTR), a derivative of Areva's Antares reactor. The future of the pebble-bed modular reactor (PBMR) for NGNP is uncertain, as the PBMR consortium partners (Westinghouse, PBMR [Pty] and The Shaw Group) were unable to agree on the path forward for NGNP during 2010. However, during the technology assessment of the conceptual design phase (Phase 1) of the NGNP project, AREVA provided design information and technology assessment of their pebble bed fueled plant design called the HTR-Module concept. AREVA does not intend to pursue this design for NGNP, preferring instead a modular reactor based on the prismatic Antares concept. Since MC&A relevant design information is available for both pebble concepts, the pebble-bed HTGRs considered in this report are: (1) Westinghouse PBMR; and (2) AREVA HTR-Module. The DOE Office of Nuclear Energy (DOE-NE) sponsors the Fuel Cycle Research and Development program (FCR&D), which contains an element specifically focused on the domestic (or state) aspects of SBD. This Material Protection, Control and Accountancy Technology (MPACT) program supports the present work summarized in this report, namely the development of guidance to support the consideration of MC&A in the design of both pebble-bed and prismatic-fueled HTGRs. The objective is to identify and incorporate design features into the facility design that will cost effectively aid in making MC&A more effective and efficient, with minimum impact on operations. The theft of nuclear material is addressed through both MC&A and physical protection, while the threat of sabotage is addressed principally through physical protection.« less

Effects of magnetic fields on improving mass transfer in flue gas desulfurization using a fluidized bed

NASA Astrophysics Data System (ADS)

Zhang, Qi; Gui, Keting; Wang, Xiaobo

2016-02-01

The effects of magnetic fields on improving the mass transfer in flue gas desulfurization using a fluidized bed are investigated in the paper. In this research, the magnetically fluidized bed (MFB) is used as the reactor in which ferromagnetic particles are fluidized with simulated flue gas under the influence of an external magnetic field. Lime slurry is continuously sprayed into the reactor. As a consequence, the desulfurization reaction and the slurry drying process take place simultaneously in the MFB. In this paper, the effects of ferromagnetic particles and external magnetic fields on the desulphurization efficiency are studied and compared with that of quartz particles as the fluidized particles. Experimental results show that the ferromagnetic particles not only act as a platform for lime slurry to precipitate on like quartz particles, but also take part in the desulfurization reaction. The results also show that the specific surface area of ferromagnetic particles after reaction is enlarged as the magnetic intensity increases, and the external magnetic field promotes the oxidation of S(IV), improving the mass transfer between sulphur and its sorbent. Hence, the efficiency of desulphurization under the effects of external magnetic fields is higher than that in general fluidized beds.

EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON

EPA Science Inventory

The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash co...

Hydrolysis and fractionation of lignocellulosic biomass

DOEpatents

Torget, Robert W.; Padukone, Nandan; Hatzis, Christos; Wyman, Charles E.

2000-01-01

A multi-function process is described for the hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components such as extractives and proteins; a portion of the solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass comprising one or more of the following: optionally, as function 1, introducing a dilute acid of pH 1.0-5.0 into a continual shrinking bed reactor containing a lignocellulosic biomass material at a temperature of about 94 to about 160.degree. C. for a period of about 10 to about 120 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of extractives, lignin, and protein by keeping the solid to liquid ratio constant throughout the solubilization process; as function 2, introducing a dilute acid of pH 1.0-5.0, either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing either fresh biomass or the partially fractionated lignocellulosic biomass material from function 1 at a temperature of about 94-220.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of hemicellulosic sugars, semisoluble sugars and other compounds, and amorphous glucans by keeping the solid to liquid ratio constant throughout the solubilization process; as function 3, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 2 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process; and as function 4, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 3 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process.

Deleterious Thermal Effects due to Randomized Flow Paths in Pebble Bed, and Particle Bed Style Reactors

NASA Technical Reports Server (NTRS)

Moran, Robert P.

2013-01-01

Reactor fuel rod surface area that is perpendicular to coolant flow direction (+S) i.e. perpendicular to the P creates areas of coolant stagnation leading to increased coolant temperatures resulting in localized changes in fluid properties. Changes in coolant fluid properties caused by minor increases in temperature lead to localized reductions in coolant mass flow rates leading to localized thermal instabilities. Reductions in coolant mass flow rates result in further increases in local temperatures exacerbating changes to coolant fluid properties leading to localized thermal runaway. Unchecked localized thermal runaway leads to localized fuel melting. Reactor designs with randomized flow paths are vulnerable to localized thermal instabilities, localized thermal runaway, and localized fuel melting.

Upflow fixed bed bioelectrochemical reactor for wastewater treatment applications.

PubMed

González-Gutiérrez, Linda; Frontana, Carlos; Martínez, Eduardo

2015-01-01

A cylindrical Upflow Fixed Bed Reactor (UFB-BER) with granular activated carbon, steel mesh electrodes and anaerobic microorganisms, was constructed for analyzing how hydrodynamic parameters affect the reactions involved during wastewater treatment processes for azo dye degradation. Dye removal percentage was not compromised by decreasing HRTm (99-90% upon changing HRTm from 4 to 1h in single pass mode). Using the residence time distribution method for hydrodynamic characterization, it was found that a higher dispersion in the reactor occurs for HRTm=1h, than for HRTm=4h. A kinetic analysis suggests that this dispersion effect could be associated to a higher specific reaction rate dependent on the azo dye concentration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Packed bed reactor for photochemical .sup.196 Hg isotope separation

DOEpatents

Grossman, Mark W.; Speer, Richard

1992-01-01

Straight tubes and randomly oriented pieces of tubing having been employed in a photochemical mercury enrichment reactor and have been found to improve the enrichment factor (E) and utilization (U) compared to a non-packed reactor. One preferred embodiment of this system uses a moving bed (via gravity) for random packing.

Nuclear Thermal Propulsion: A Joint NASA/DOE/DOD Workshop

NASA Technical Reports Server (NTRS)

Clark, John S. (Editor)

1991-01-01

Papers presented at the joint NASA/DOE/DOD workshop on nuclear thermal propulsion are compiled. The following subject areas are covered: nuclear thermal propulsion programs; Rover/NERVA and NERVA systems; Low Pressure Nuclear Thermal Rocket (LPNTR); particle bed reactor nuclear rocket; hybrid propulsion systems; wire core reactor; pellet bed reactor; foil reactor; Droplet Core Nuclear Rocket (DCNR); open cycle gas core nuclear rockets; vapor core propulsion reactors; nuclear light bulb; Nuclear rocket using Indigenous Martian Fuel (NIMF); mission analysis; propulsion and reactor technology; development plans; and safety issues.

Pressurized fluidized bed reactor

DOEpatents

Isaksson, J.

1996-03-19

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

Pressurized fluidized bed reactor

DOEpatents

Isaksson, Juhani

1996-01-01

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield

PubMed Central

Araújo, Paulo Jardel P.; Leite, Manuela Souza; Kakuta Ravagnani, Teresa M.

2016-01-01

Styrene is an important monomer in the manufacture of thermoplastic. Most of it is produced by the catalytic dehydrogenation of ethylbenzene. In this process that depends on reversible reactions, the yield is usually limited by the establishment of thermodynamic equilibrium in the reactor. The styrene yield can be increased by using a hybrid process, with reaction and separation simultaneously. It is proposed using permselective composite membrane to remove hydrogen and thus suppress the reverse and secondary reactions. This paper describes the simulation of a dehydrogenation process carried out in a tubular fixed-bed reactor wrapped in a permselective composite membrane. A mathematical model was developed, incorporating the various mass transport mechanisms found in each of the membrane layers and in the catalytic fixed bed. The effects of the reactor feed conditions (temperature, steam-to-oil ratio, and the weight hourly space velocity), the fixed-bed geometry (length, diameter, and volume), and the membrane geometry (thickness of the layers) on the styrene yield were analyzed. These variables were used to determine experimental conditions that favour the production of styrene. The simulation showed that an increase of 40.98% in the styrene yield, compared to a conventional fixed-bed process, could be obtained by wrapping the reactor in a permselective composite membrane. PMID:27069982

JPL in-house fluidized-bed reactor research

NASA Technical Reports Server (NTRS)

Rohatgi, N. K.

1984-01-01

Fluidized bed reactor research techniques for fabrication of quartz linears was reviewed. Silane pyrolysis was employed in this fabrication study. Metallic contaminant levels in the silicon particles were below levels detectable by emission spectroscopy.

Catalytic fast pyrolysis of white oak wood in-situ using a bubbling fluidized bed reactor

USDA-ARS?s Scientific Manuscript database

Catalytic fast pyrolysis was performed on white oak wood using two zeolite-type catalysts as bed material in a bubbling fluidized bed reactor. The two catalysts chosen, based on a previous screening study, were Ca2+ exchanged Y54 (Ca-Y54) and a proprietary ß-zeolite type catalyst (catalyst M) both ...

Particulate fuel bed tests

NASA Astrophysics Data System (ADS)

Horn, F. L.; Powell, J. R.; Savino, J. M.

Gas-cooled reactors using packed beds of small-diameter, coated fuel particles have been proposed for compact, high-power systems. To test the thermal-hydraulic performance of the particulate reactor fuel under simulated reactor conditions, a bed of 800-micrometer diameter particles was heated by its electrical resistance current and cooled by flowing helium gas. The specific resistance of the bed composed of pyrocarbon-coated particles was measured at several temperatures, and found to be 0.09 ohm-cm at 1273 K and 0.06 ohm-cm at 1600 K. The maximum bed power density reached was 1500 W/cu cm at 1500 K. The pressure drop followed the packed-bed correlation, typically 100,000 Pa/cm. The various frit materials used to contain the bed were also tested to 2000 K in helium and hydrogen to determine their properties and reactions with the fuel. Rhenium metal, zirconium carbide, and zirconium oxide appeared to be the best candidate materials, while tungsten and tungsten-rhenium lost mass and strength.

Immobilized lysozyme for the continuous lysis of lactic bacteria in wine: Bench-scale fluidized-bed reactor study.

PubMed

Cappannella, Elena; Benucci, Ilaria; Lombardelli, Claudio; Liburdi, Katia; Bavaro, Teodora; Esti, Marco

2016-11-01

Lysozyme from hen egg white (HEWL) was covalently immobilized on spherical supports based on microbial chitosan in order to develop a system for the continuous, efficient and food-grade enzymatic lysis of lactic bacteria (Oenococcus oeni) in white and red wine. The objective is to limit the sulfur dioxide dosage required to control malolactic fermentation, via a cell concentration typical during this process. The immobilization procedure was optimized in batch mode, evaluating the enzyme loading, the specific activity, and the kinetic parameters in model wine. Subsequently, a bench-scale fluidized-bed reactor was developed, applying the optimized process conditions. HEWL appeared more effective in the immobilized form than in the free one, when the reactor was applied in real white and red wine. This preliminary study suggests that covalent immobilization renders the enzyme less sensitive to the inhibitory effect of wine flavans. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of operating pressure on the biological hydrogen methanation in trickle-bed reactors.

PubMed

Ullrich, Timo; Lindner, Jonas; Bär, Katharina; Mörs, Friedemann; Graf, Frank; Lemmer, Andreas

2018-01-01

In order to investigate the influence of pressures up to 9bar absolute on the productivity of trickle-bed reactors for biological methanation of hydrogen and carbon dioxide, experiments were carried out in a continuously operated experimental plant with three identical reactors. The pressure increase promises a longer residence time and improved mass transfer of H 2 due to higher gas partial pressures. The study covers effects of different pressures on important parameters like gas hourly space velocity, methane formation rate, conversion rates and product gas quality. The methane content of 64.13±3.81vol-% at 1.5bar could be increased up to 86.51±0.49vol-% by raising the pressure to 9bar. Methane formation rates of up to 4.28±0.26m 3 m -3 d -1 were achieved. Thus, pressure increase could significantly improve reactor performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous fermentation and separation in an immobilized cell trickle bed reactor: Acetone-butanol-ethane (ABE) and ethanol fermentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, C.H.

1989-01-01

A novel process employing immobilized cells and in-situ product removal was studied for acetone-butanol-ethanol (ABE) fermentation by Clostridium acetobutylicum and ethanol fermentation by Saccharomyces cerevisiae. Experimental studies of ABE fermentation in a trickle bed reactor without product separation showed that solvent production could be improved by one order of magnitude compared to conventional batch fermentation. Control of effluent pH near 4.3 and feed glucose concentrations higher than 10 g/L were the necessary conditions for cell growth and solvent production. A mathematical model using an equilibrium staged model predicted efficient separation of butanol from the fermentation broth. Activity coefficients of multicomponentmore » system were estimated by Wilson's equation or the ASOG method. Inhibition by butanol and organic acids was incorporated into the kinetic expression. Experimental performance of simultaneous fermentation and separation in an immobilized cell trickle bed reactor showed that glucose conversion was improved as predicted by mathematical modeling and analysis. The effect of pH and temperature on ethanol fermentation by Saccharomyces cerevisiae was studied in free and immobilized cell reactors. Conditions for the highest glucose conversion, cell viability and least glycerol yield were determined.« less

A CFD model for biomass fast pyrolysis in fluidized-bed reactors

NASA Astrophysics Data System (ADS)

Xue, Qingluan; Heindel, T. J.; Fox, R. O.

2010-11-01

A numerical study is conducted to evaluate the performance and optimal operating conditions of fluidized-bed reactors for fast pyrolysis of biomass to bio-oil. A comprehensive CFD model, coupling a pyrolysis kinetic model with a detailed hydrodynamics model, is developed. A lumped kinetic model is applied to describe the pyrolysis of biomass particles. Variable particle porosity is used to account for the evolution of particle physical properties. The kinetic scheme includes primary decomposition and secondary cracking of tar. Biomass is composed of reference components: cellulose, hemicellulose, and lignin. Products are categorized into groups: gaseous, tar vapor, and solid char. The particle kinetic processes and their interaction with the reactive gas phase are modeled with a multi-fluid model derived from the kinetic theory of granular flow. The gas, sand and biomass constitute three continuum phases coupled by the interphase source terms. The model is applied to investigate the effect of operating conditions on the tar yield in a fluidized-bed reactor. The influence of various parameters on tar yield, including operating temperature and others are investigated. Predicted optimal conditions for tar yield and scale-up of the reactor are discussed.

Generation and Reduction of NOx on Air-Fed Ozonizers

NASA Astrophysics Data System (ADS)

Ehara, Yoshiyasu; Amemiya, Yusuke; Yamamoto, Toshiaki

A generation and reduction of NOx on air-fed ozonizers using a ferroelectric packed bed reactor have been experimentally investigated. The reactors packed with CaTiO3, SrTiO3 and BaTiO3 pellets are examined for ozone generation. An ac voltage is applied to the reactor to generate partial discharge. Ozone concentration and the different nitrogen oxides at downstream of the packed bed reactor were measured with UV absorption ozone monitor and a Fourier transform infrared spectroscope respectively. The dielectric constant of packed ferroelectric pellets influences the discharge characteristic, ozone and NOx generations are varied by the dielectric constant value. Focusing on a discharge pulse current and maximum discharge magnitude, the ferroelectric packed bed plasma reactors have been evaluated on nitrogen oxide and ozone generated concentrations.

Batch Tests To Determine Activity Distribution and Kinetic Parameters for Acetate Utilization in Expanded-Bed Anaerobic Reactors

PubMed Central

Fox, Peter; Suidan, Makram T.

1990-01-01

Batch tests to measure maximum acetate utilization rates were used to determine the distribution of acetate utilizers in expanded-bed sand and expanded-bed granular activated carbon (GAC) reactors. The reactors were fed a mixture of acetate and 3-ethylphenol, and they contained the same predominant aceticlastic methanogen, Methanothrix sp. Batch tests were performed both on the entire reactor contents and with media removed from the reactors. Results indicated that activity was evenly distributed within the GAC reactors, whereas in the sand reactor a sludge blanket on top of the sand bed contained approximately 50% of the activity. The Monod half-velocity constant (Ks) for the acetate-utilizing methanogens in two expanded-bed GAC reactors was searched for by combining steady-state results with batch test data. All parameters necessary to develop a model with Monod kinetics were experimentally determined except for Ks. However, Ks was a function of the effluent 3-ethylphenol concentration, and batch test results demonstrated that maximum acetate utilization rates were not a function of the effluent 3-ethylphenol concentration. Addition of a competitive inhibition term into the Monod expression predicted the dependence of Ks on the effluent 3-ethylphenol concentration. A two-parameter search determined a Ks of 8.99 mg of acetate per liter and a Ki of 2.41 mg of 3-ethylphenol per liter. Model predictions were in agreement with experimental observations for all effluent 3-ethylphenol concentrations. Batch tests measured the activity for a specific substrate and determined the distribution of activity in the reactor. The use of steady-state data in conjunction with batch test results reduced the number of unknown kinetic parameters and thereby reduced the uncertainty in the results and the assumptions made. PMID:16348175

Batch tests to determine activity distribution and kinetic parameters for acetate utilization in expanded-bed anaerobic reactors.

PubMed

Fox, P; Suidan, M T

1990-04-01

Batch tests to measure maximum acetate utilization rates were used to determine the distribution of acetate utilizers in expanded-bed sand and expanded-bed granular activated carbon (GAC) reactors. The reactors were fed a mixture of acetate and 3-ethylphenol, and they contained the same predominant aceticlastic methanogen, Methanothrix sp. Batch tests were performed both on the entire reactor contents and with media removed from the reactors. Results indicated that activity was evenly distributed within the GAC reactors, whereas in the sand reactor a sludge blanket on top of the sand bed contained approximately 50% of the activity. The Monod half-velocity constant (K(s)) for the acetate-utilizing methanogens in two expanded-bed GAC reactors was searched for by combining steady-state results with batch test data. All parameters necessary to develop a model with Monod kinetics were experimentally determined except for K(s). However, K(s) was a function of the effluent 3-ethylphenol concentration, and batch test results demonstrated that maximum acetate utilization rates were not a function of the effluent 3-ethylphenol concentration. Addition of a competitive inhibition term into the Monod expression predicted the dependence of K(s) on the effluent 3-ethylphenol concentration. A two-parameter search determined a K(s) of 8.99 mg of acetate per liter and a K(i) of 2.41 mg of 3-ethylphenol per liter. Model predictions were in agreement with experimental observations for all effluent 3-ethylphenol concentrations. Batch tests measured the activity for a specific substrate and determined the distribution of activity in the reactor. The use of steady-state data in conjunction with batch test results reduced the number of unknown kinetic parameters and thereby reduced the uncertainty in the results and the assumptions made.

Flash hydrogenation of coal

DOEpatents

Manowitz, Bernard; Steinberg, Meyer; Sheehan, Thomas V.; Winsche, Warren E.; Raseman, Chad J.

1976-01-01

A process for the hydrogenation of coal comprising the contacting of powdered coal with hydrogen in a rotating fluidized bed reactor. A rotating fluidized bed reactor suitable for use in this process is also disclosed. The coal residence time in the reactor is limited to less than 5 seconds while the hydrogen contact time is not in excess of 0.2 seconds.

Numerical Study of Pyrolysis of Biomass in Fluidized Beds

NASA Technical Reports Server (NTRS)

Bellan, Josette; Lathouwers, Danny

2003-01-01

A report presents a numerical-simulation study of pyrolysis of biomass in fluidized-bed reactors, performed by use of the mathematical model described in Model of Fluidized Bed Containing Reacting Solids and Gases (NPO-30163), which appears elsewhere in this issue of NASA Tech Briefs. The purpose of the study was to investigate the effect of various operating conditions on the efficiency of production of condensable tar from biomass. The numerical results indicate that for a fixed particle size, the fluidizing-gas temperature is the foremost parameter that affects the tar yield. For the range of fluidizing-gas temperatures investigated, and under the assumption that the pyrolysis rate exceeds the feed rate, the optimum steady-state tar collection was found to occur at 750 K. In cases in which the assumption was not valid, the optimum temperature for tar collection was found to be only slightly higher. Scaling up of the reactor was found to exert a small negative effect on tar collection at the optimal operating temperature. It is also found that slightly better scaling is obtained by use of shallower fluidized beds with greater fluidization velocities.

Application of a fluidized bed reactor charged with aragonite for control of alkalinity, pH and carbon dioxide in marine recirculating aquaculture systems

USGS Publications Warehouse

Paul S Wills, PhD; Pfeiffer, Timothy; Baptiste, Richard; Watten, Barnaby J.

2016-01-01

Control of alkalinity, dissolved carbon dioxide (dCO2), and pH are critical in marine recirculating aquaculture systems (RAS) in order to maintain health and maximize growth. A small-scale prototype aragonite sand filled fluidized bed reactor was tested under varying conditions of alkalinity and dCO2 to develop and model the response of dCO2 across the reactor. A large-scale reactor was then incorporated into an operating marine recirculating aquaculture system to observe the reactor as the system moved toward equilibrium. The relationship between alkalinity dCO2, and pH across the reactor are described by multiple regression equations. The change in dCO2 across the small-scale reactor indicated a strong likelihood that an equilibrium alkalinity would be maintained by using a fluidized bed aragonite reactor. The large-scale reactor verified this observation and established equilibrium at an alkalinity of approximately 135 mg/L as CaCO3, dCO2 of 9 mg/L, and a pH of 7.0 within 4 days that was stable during a 14 day test period. The fluidized bed aragonite reactor has the potential to simplify alkalinity and pH control, and aid in dCO2 control in RAS design and operation. Aragonite sand, purchased in bulk, is less expensive than sodium bicarbonate and could reduce overall operating production costs.

Treatment of synthetic refinery wastewater in anoxic-aerobic sequential moving bed reactors and sulphur recovery.

PubMed

Mallick, Subrat Kumar; Chakraborty, Saswati

2017-11-10

Objective of the present study was to simultaneously biodegrade synthetic petroleum refinery wastewater containing phenol (750 mg/L), sulphide (750 mg/L), hydrocarbon (as emulsified diesel of 300 mg/L), ammonia-nitrogen (350 mg/L) at pH >9 in anoxic-aerobic sequential moving bed reactors. The optimum mixing speed of anoxic reactor was observed at 20 rpm and beyond that, removal rate remained constant. In anoxic reactor the minimum hydraulic retention time was observed to be 2 days for complete removal of sulphide, 40-50% removal of phenol and total hydrocarbons and 52% of sulphur recovery. The optimum HRT of aerobic moving bed reactor was observed as 16 h (total HRT of 64 h for anoxic and aerobic reactors) for complete removals of phenol, total hydrocarbons, COD (chemical oxygen demand) and ammonia-nitrogen with nitrification.

Fluidized bed silicon deposition from silane

NASA Technical Reports Server (NTRS)

Hsu, George C. (Inventor); Levin, Harry (Inventor); Hogle, Richard A. (Inventor); Praturi, Ananda (Inventor); Lutwack, Ralph (Inventor)

1982-01-01

A process and apparatus for thermally decomposing silicon containing gas for deposition on fluidized nucleating silicon seed particles is disclosed. Silicon seed particles are produced in a secondary fluidized reactor by thermal decomposition of a silicon containing gas. The thermally produced silicon seed particles are then introduced into a primary fluidized bed reactor to form a fluidized bed. Silicon containing gas is introduced into the primary reactor where it is thermally decomposed and deposited on the fluidized silicon seed particles. Silicon seed particles having the desired amount of thermally decomposed silicon product thereon are removed from the primary fluidized reactor as ultra pure silicon product. An apparatus for carrying out this process is also disclosed.

Fluidized bed silicon deposition from silane

NASA Technical Reports Server (NTRS)

Hsu, George (Inventor); Levin, Harry (Inventor); Hogle, Richard A. (Inventor); Praturi, Ananda (Inventor); Lutwack, Ralph (Inventor)

1984-01-01

A process and apparatus for thermally decomposing silicon containing gas for deposition on fluidized nucleating silicon seed particles is disclosed. Silicon seed particles are produced in a secondary fluidized reactor by thermal decomposition of a silicon containing gas. The thermally produced silicon seed particles are then introduced into a primary fluidized bed reactor to form a fludized bed. Silicon containing gas is introduced into the primary reactor where it is thermally decomposed and deposited on the fluidized silicon seed particles. Silicon seed particles having the desired amount of thermally decomposed silicon product thereon are removed from the primary fluidized reactor as ultra pure silicon product. An apparatus for carrying out this process is also disclosed.

Effects of water vapor pretreatment time and reaction temperature on CO(2) capture characteristics of a sodium-based solid sorbent in a bubbling fluidized-bed reactor.

PubMed

Seo, Yongwon; Jo, Sung-Ho; Ryu, Chong Kul; Yi, Chang-Keun

2007-10-01

CO(2) capture from flue gas using a sodium-based solid sorbent was investigated in a bubbling fluidized-bed reactor. Carbonation and regeneration temperature on CO(2) removal was determined. The extent of the chemical reactivity after carbonation or regeneration was characterized via (13)C NMR. In addition, the physical properties of the sorbent such as pore size, pore volume, and surface area after carbonation or regeneration were measured by gas adsorption method (BET). With water vapor pretreatment, near complete CO(2) removal was initially achieved and maintained for about 1-2min at 50 degrees C with 2s gas residence time, while without proper water vapor pretreatment CO(2) removal abruptly decreased from the beginning. Carbonation was effective at the lower temperature over the 50-70 degrees C temperature range, while regeneration more effective at the higher temperature over the 135-300 degrees C temperature range. To maintain the initial 90% CO(2) removal, it would be necessary to keep the regeneration temperature higher than about 135 degrees C. The results obtained in this study can be used as basic data for designing and operating a large scale CO(2) capture process with two fluidized-bed reactors.

Coal hydrogenation and deashing in ebullated bed catalytic reactor

DOEpatents

Huibers, Derk T. A.; Johanson, Edwin S.

1983-01-01

An improved process for hydrogenation of coal containing ash with agglomeration and removal of ash from an ebullated bed catalytic reactor to produce deashed hydrocarbon liquid and gas products. In the process, a flowable coal-oil slurry is reacted with hydrogen in an ebullated catalyst bed reaction zone at elevated temperature and pressure conditions. The upward velocity and viscosity of the reactor liquid are controlled so that a substantial portion of the ash released from the coal is agglomerated to form larger particles in the upper portion of the reactor above the catalyst bed, from which the agglomerated ash is separately withdrawn along with adhering reaction zone liquid. The resulting hydrogenated hydrocarbon effluent material product is phase separated to remove vapor fractions, after which any ash remaining in the liquid fraction can be removed to produce substantially ash-free coal-derived liquid products.

TiO2-photocatalyzed As(III) oxidation in a fixed-bed, flow-through reactor.

PubMed

Ferguson, Megan A; Hering, Janet G

2006-07-01

Compliance with the U.S. drinking water standard for arsenic (As) of 10 microg L(-1) is required in January 2006. This will necessitate implementation of treatment technologies for As removal by thousands of water suppliers. Although a variety of such technologies is available, most require preoxidation of As(III) to As(V) for efficient performance. Previous batch studies with illuminated TiO2 slurries have demonstrated that TiO2-photocatalyzed AS(III) oxidation occurs rapidly. This study examined reaction efficiency in a flow-through, fixed-bed reactor that provides a better model for treatment in practice. Glass beads were coated with mixed P25/sol gel TiO2 and employed in an upflow reactor irradiated from above. The reactor residence time, influent As(III) concentration, number of TiO2 coatings on the beads, solution matrix, and light source were varied to characterize this reaction and determine its feasibility for water treatment. Repeated usage of the same beads in multiple experiments or extended use was found to affect effluent As(V) concentrations but not the steady-state effluent As(III) concentration, which suggests that As(III) oxidation at the TiO2 surface undergoes dynamic sorption equilibration. Catalyst poisoning was not observed either from As(V) or from competitively adsorbing anions, although the higher steady-state effluent As(III) concentrations in synthetic groundwater compared to 5 mM NaNO3 indicated that competitive sorbates in the matrix partially hinder the reaction. A reactive transport model with rate constants proportional to incident light at each bead layer fit the experimental data well despite simplifying assumptions. TiO2-photocatalyzed oxidation of As(III) was also effective under natural sunlight. Limitations to the efficiency of As(III) oxidation in the fixed-bed reactor were attributable to constraints of the reactor geometry, which could be overcome by improved design. The fixed-bed TiO2 reactor offers an environmentally benign method for As(III) oxidation.

Anaerobic digestion of olive mill wastewaters in biofilm reactors packed with granular activated carbon and "Manville" silica beads.

PubMed

Bertin, Lorenzo; Berselli, Sara; Fava, Fabio; Petrangeli-Papini, Marco; Marchetti, Leonardo

2004-01-01

Anaerobic digestion is one of the most promising technologies for disposing olive mill wastewaters (OMWs). The process is generally carried out in the conventional contact bioreactors, which however are often unable to efficiently remove OMW phenolic compounds, that therefore occur in the effluents. The possibility of mitigating this problem by employing an anaerobic OMW-digesting microbial consortium passively immobilized in column reactors packed with granular activated carbon (GAC) or "Manville" silica beads (SB) was here investigated. Under batch conditions, both GAC- and SB-packed-bed biofilm reactors exhibited OMW COD and phenolic compound removal efficiencies markedly higher (from 60% to 250%) than those attained in a parallel anaerobic dispersed growth reactor developed with the same inoculum; GAC-reactor exhibited COD and phenolic compound depletion yields higher by 62% and 78%, respectively, than those achieved with the identically configured SB-biofilm reactor. Both biofilm reactors also mediated an extensive OMW remediation under continuous conditions, where GAC-reactor was much more effective than the corresponding SB-one, and showed a tolerance to high and variable organic loads along with a volumetric productivity in terms of COD and phenolic compound removal significantly higher than those averagely displayed by most of the conventional and packed-bed laboratory-scale reactors previously proposed for the OMW digestion.

[Kinetics of catalytic wet air oxidation of phenol in trickle bed reactor].

PubMed

Li, Guang-ming; Zhao, Jian-fu; Wang, Hua; Zhao, Xiu-hua; Zhou, Yang-yuan

2004-05-01

By using a trickle bed reactor which was designed by the authors, the catalytic wet air oxidation reaction of phenol on CuO/gamma-Al2O3 catalyst was studied. The results showed that in mild operation conditions (at temperature of 180 degrees C, pressure of 3 MPa, liquid feed rate of 1.668 L x h(-1) and oxygen feed rate of 160 L x h(-1)), the removal of phenol can be over 90%. The curve of phenol conversion is similar to "S" like autocatalytic reaction, and is accordance with chain reaction of free radical. The kinetic model of pseudo homogenous reactor fits the catalytic wet air oxidation reaction of phenol. The effects of initial concentration of phenol, liquid feed rate and temperature for reaction also were investigated.

Anaerobic treatment of winery wastewater in fixed bed reactors.

PubMed

Ganesh, Rangaraj; Rajinikanth, Rajagopal; Thanikal, Joseph V; Ramanujam, Ramamoorty Alwar; Torrijos, Michel

2010-06-01

The treatment of winery wastewater in three upflow anaerobic fixed-bed reactors (S9, S30 and S40) with low density floating supports of varying size and specific surface area was investigated. A maximum OLR of 42 g/l day with 80 +/- 0.5% removal efficiency was attained in S9, which had supports with the highest specific surface area. It was found that the efficiency of the reactors increased with decrease in size and increase in specific surface area of the support media. Total biomass accumulation in the reactors was also found to vary as a function of specific surface area and size of the support medium. The Stover-Kincannon kinetic model predicted satisfactorily the performance of the reactors. The maximum removal rate constant (U(max)) was 161.3, 99.0 and 77.5 g/l day and the saturation value constant (K(B)) was 162.0, 99.5 and 78.0 g/l day for S9, S30 and S40, respectively. Due to their higher biomass retention potential, the supports used in this study offer great promise as media in anaerobic fixed bed reactors. Anaerobic fixed-bed reactors with these supports can be applied as high-rate systems for the treatment of large volumes of wastewaters typically containing readily biodegradable organics, such as the winery wastewater.

Pressurized fluidized bed reactor and a method of operating the same

DOEpatents

Isaksson, J.

1996-02-20

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

Pressurized fluidized bed reactor and a method of operating the same

DOEpatents

Isaksson, Juhani

1996-01-01

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

Partial nitritation of raw anaerobic sludge digester liquor by swim-bed and swim-bed activated sludge processes and comparison of their sludge characteristics.

PubMed

Qiao, Sen; Kawakubo, Yuki; Koyama, Toichiro; Furukawa, Kenji

2008-11-01

This study evaluated performance of swim-bed (SB) reactors packed with a novel acrylic fiber carrier (BF) and swim-bed activated sludge (SBAS) reactor for partial nitritation of anaerobic sludge digester liquor from a municipal wastewater treatment plant. Comparison of characteristics of sludge obtained from both the reactors was also made. The average conversion rates of ammonium to nitrite were 52.3% and 40.0% under relatively high nitrogen loading rates over 3.0 kg-N/m(3)/d, respectively in two reactors. The average BOD(5) removal efficiencies were 74.3% and 64.4%, respectively in the two reactors. The size of the sludge pellets taken from SB and SBAS reactors was found to be approximately three times (229 mum versus 88 mum) of that of the seed sludge. This sludge also had relatively high extracellular proteins levels indicating better sludge settling capability as compared to the sludge taken from SBAS reactor. Although the effluent nitrite/ammonium ratios had fluctuated in both reactor in some extent, the low dissolved oxygen concentration (average of 2.5 versus 0.35 mg/l), low suspended solids (average of 33.3 versus 33.5 mg/l), and about 50% ammonium conversion to nitrite demonstrated the application potential of anammox process for nitrogen removal.

Effect of air-assisted backwashing on the performance of an anaerobic fixed-bed bioreactor that simultaneously removes nitrate and arsenic from drinking water sources.

PubMed

Upadhyaya, Giridhar; Clancy, Tara M; Snyder, Kathryn V; Brown, Jess; Hayes, Kim F; Raskin, Lutgarde

2012-03-15

Contaminant removal from drinking water sources under reducing conditions conducive for the growth of denitrifying, arsenate reducing, and sulfate reducing microbes using a fixed-bed bioreactor may require oxygen-free gas (e.g., N2 gas) during backwashing. However, the use of air-assisted backwashing has practical advantages, including simpler operation, improved safety, and lower cost. A study was conducted to evaluate whether replacing N2 gas with air during backwashing would impact performance in a nitrate and arsenic removing anaerobic bioreactor system that consisted of two biologically active carbon reactors in series. Gas-assisted backwashing, comprised of 2 min of gas injection to fluidize the bed and dislodge biomass and solid phase products, was performed in the first reactor (reactor A) every two days. The second reactor (reactor B) was subjected to N2 gas-assisted backwashing every 3-4 months. Complete removal of 50 mg/L NO3- was achieved in reactor A before and after the switch from N2-assisted backwashing (NAB) to air-assisted backwashing (AAB). Substantial sulfate removal was achieved with both backwashing strategies. Prolonged practice of AAB (more than two months), however, diminished sulfate reduction in reactor B somewhat. Arsenic removal in reactor A was impacted slightly by long-term use of AAB, but arsenic removals achieved by the entire system during NAB and AAB periods were not significantly different (p>0.05) and arsenic concentrations were reduced from approximately 200 μg/L to below 20 μg/L. These results indicate that AAB can be implemented in anaerobic nitrate and arsenic removal systems. Copyright © 2011 Elsevier Ltd. All rights reserved.

Characterization and anaerobic treatment of the sanitary landfill leachate in Istanbul.

PubMed

Inanc, B; Calli, B; Saatci, A

2000-01-01

In this study, characterization and anaerobic treatability of leachate from Komurcuoda Sanitary Landfill located on the Asian part of Istanbul were investigated. Time based fluctuations in characteristics of leachate were monitored for an 8 month period. Samples were taken from a 200 m3 holding tank located at the lowest elevation of the landfill. COD concentrations have ranged between 18,800 and 47,800 mg/l while BOD5 between 6820 and 38,500 mg/L. COD and BOD5 values were higher in summer and lower in winter due to dilution by precipitation. On the other hand, it was quite interesting that such a dilution effect was not observed for ammonia. The highest ammonia concentration, 2690 mg/L was in November 1998. BOD5/COD ratio was larger than 0.7 for most samples indicating high biodegradability, and acidic phase of decomposition in the landfill. For anaerobic treatability, three different reactors, namely an upflow anaerobic sludge bed reactor, an anaerobic upflow filter and a hybrid bed reactor, were used. The anaerobic reactors were operated for more than 230 days and were continuing operation when this paper was prepared. Organic loading was increased gradually from 1.3 kg COD/m3.day to 8.2 kg COD/m3.day while hydraulic retention time was reduced from 2.4 days to 2.0 days. All the reactors showed similar performances against organic loadings with efficiencies between 80% and 90%. However the reactors have experienced high ammonia concentrations several times throughout the experimental period, and showed different inhibition levels. Anaerobic filter was the least affected reactor while UASB was the most. Hybrid bed reactor has exhibited a similar performance to anaerobic filter although not to the same degree.

Removal of oxytetracycline (OTC) in a synthetic pharmaceutical wastewater by a sequential anaerobic multichamber bed reactor (AMCBR)/completely stirred tank reactor (CSTR) system: biodegradation and inhibition kinetics.

PubMed

Sponza, Delia Teresa; Çelebi, Hakan

2012-01-01

An anaerobic multichamber bed reactor (AMCBR) was effective in removing both molasses-chemical oxygen demand (COD), and the antibiotic oxytetracycline (OTC). The maximum COD and OTC removals were 99% in sequential AMCBR/completely stirred tank reactor (CSTR) at an OTC concentration of 300 mg L(-1). 51%, 29% and 9% of the total volatile fatty acid (TVFA) was composed of acetic, propionic acid and butyric acids, respectively. The OTC loading rates at between 22.22 and 133.33 g OTC m(-3) d(-1) improved the hydrolysis of molasses-COD (k), the maximum specific utilization of molasses-COD (k(mh)) and the maximum specific utilization rate of TVFA (k(TVFA)). The direct effect of high OTC loadings (155.56 and -177.78 g OTC m(-3) d(-1)) on acidogens and methanogens were evaluated with Haldane inhibition kinetic. A significant decrease of the Haldane inhibition constant was indicative of increases in toxicity at increasing loading rates. Copyright © 2011 Elsevier Ltd. All rights reserved.

Optimization of food waste hydrolysis in leach bed coupled with methanogenic reactor: effect of pH and bulking agent.

PubMed

Xu, Su Yun; Lam, Hoi Pui; Karthikeyan, O Parthiba; Wong, Jonathan W C

2011-02-01

The effects of pH and bulking agents on hydrolysis/acidogenesis of food waste were studied using leach bed reactor (LBR) coupled with methanogenic up-flow anaerobic sludge blanket (UASB) reactor. The hydrolysis rate under regulated pH (6.0) was studied and compared with unregulated one during initial experiment. Then, the efficacies of five different bulking agents, i.e. plastic full particles, plastic hollow sphere, bottom ash, wood chip and saw dust were experimented under the regulated pH condition. Leachate recirculation with 50% water replacement was practiced throughout the experiment. Results proved that the daily leachate recirculation with pH control (6.0) accelerated the hydrolysis rate (59% higher volatile fatty acids) and methane production (up to 88%) compared to that of control without pH control. Furthermore, bottom ash improved the reactor alkalinity, which internally buffered the system that improved the methane production rate (0.182 l CH(4)/g VS(added)) than other bulking agents. Copyright © 2010 Elsevier Ltd. All rights reserved.

Anaerobic/aerobic treatment of a petrochemical wastewater from two aromatic transformation processes by fluidized bed reactors.

PubMed

Estrada-Arriaga, Edson B; Ramirez-Camperos, Esperanza; Moeller-Chavez, Gabriela E; García-Sanchez, Liliana

2012-01-01

An integrated fluidized bed reactor (FBR) has been employed as the treatment for petrochemical industry wastewaters with high organic matter and aromatic compounds, under anaerobic and aerobic conditions. The system was operated at hydraulic residence time (HRT) of 2.7 and 2.2 h in the anaerobic and aerobic reactor, respectively. The degree of fluidization in the beds was 30%. This system showed a high performance on the removal of organic matter and aromatic compounds. At different organic loading rates (OLR), the chemical oxygen demand (COD) removal in the anaerobic reactor was close to 85% and removals of the COD up to 94% were obtained in the aerobic reactor. High removals of benzene, toluene, ethylbenzene, xylenes, styrene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene and naphthalene were achieved in this study.

Power Peaking Effect of OTTO Fuel Scheme Pebble Bed Reactor

NASA Astrophysics Data System (ADS)

Setiadipura, T.; Suwoto; Zuhair; Bakhri, S.; Sunaryo, G. R.

2018-02-01

Pebble Bed Reactor (PBR) type of Hight Temperature Gas-cooled Reactor (HTGR) is a very interesting nuclear reactor design to fulfill the growing electricity and heat demand with a superior passive safety features. Effort to introduce the PBR design to the market can be strengthen by simplifying its system with the Once-through-then-out (OTTO) cycle PBR in which the pebble fuel only pass the core once. Important challenge in the OTTO fuel scheme is the power peaking effect which limit the maximum nominal power or burnup of the design. Parametric survey is perform in this study to investigate the contribution of different design parameters to power peaking effect of OTTO cycle PBR. PEBBED code is utilized in this study to perform the equilibrium PBR core analysis for different design parameter and fuel scheme. The parameters include its core diameter, height-per-diameter (H/D), power density, and core nominal power. Results of this study show that diameter and H/D effectsare stronger compare to the power density and nominal core power. Results of this study might become an importance guidance for design optimization of OTTO fuel scheme PBR.

Bubbling bed catalytic hydropyrolysis process utilizing larger catalyst particles and smaller biomass particles featuring an anti-slugging reactor

DOEpatents

Marker, Terry L; Felix, Larry G; Linck, Martin B; Roberts, Michael J

2014-09-23

This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

Bubbling bed catalytic hydropyrolysis process utilizinig larger catalyst particles and small biomass particles featuring an anti-slugging reactor

DOEpatents

Marker, Terry L.; Felix, Larry G.; Linck, Martin B.; Roberts, Michael J.

2016-12-06

This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies.

PubMed

Rahman, N K; Kamaruddin, A H; Uzir, M H

2011-08-01

The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.

Influence of vegetation and gravel mesh on the tertiary treatment of wastewater from a cosmetics industry.

PubMed

Vlyssides, Apostolos G; Mai, Sofia T H; Barampouti, Elli Maria P; Loukakis, Haralampos N

2009-07-01

To estimate the influence of gravel mesh (fine and coarse) and vegetation (Phragmites and Arundo) on the efficiency of a reed bed, a pilot plant was included after the wastewater treatment plant of a cosmetic industry treatment system according to a 22 factorial experimental design. The maximum biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and total phosphorous (TP) reduction was observed in the reactor, where Phragmites and fine gravel were used. In the reactor with Phragmites and coarse gravel, the maximum total Kjeldahl nitrogen (TKN) and total suspended solids (TSS) reduction was observed. The maximum total solids reduction was measured in the reed bed, which was filled with Arundo and coarse gravel. Conclusively, the treatment of a cosmetic industry's wastewater by reed beds as a tertiary treatment method is quite effective.

Design of fluidized-bed fermentors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrews, G.F.; Przezdziecki, J.

1986-06-01

Designing a fluidized-bed bioreactor requires choosing the best support particle (if any). Effectiveness factors (proportional to reactor volumetric productivity) are derived for flocs, solid spherical supports, porous supports, and adsorbent supports. The derivation demonstrates a mathematical procedure for reducing the diffusion/uptake equations for many components (substrates and inhibitory products) to a single equation, and for identifying the limiting component. With solid supports there exists a film thickness that maximizes the effectiveness, and the design objective is to keep the film near this optimum throughout the bed. This involves consideration of the effect of support particle density and film growth onmore » bed stratification. Other considerations in packing support particles are obtaining reasonable values for bed height and diameter, minimizing mass transfer resistance between liquid and biomass, and preventing surface shear from stripping off the biomass. 20 references.« less

Treatment of semivolatile compounds in high strength wastes using an anaerobic expanded-bed GAC reactor

EPA Science Inventory

The potential of the anaerobic, expanded bed granular activated carbon (GAC) reactor in treating a high strength waste containing RCRA semivolatile organic compounds (VOCs) was studied. Six semivolatiles, orthochlorophenol, nitrobenzene, naphthalene, para-nitrophenol, lindane, a...

Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

PubMed

Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

2016-07-28

To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas.

Co-pyrolysis behaviors of saw dust and Shenfu coal in drop tube furnace and fixed bed reactor.

PubMed

Li, Shuaidan; Chen, Xueli; Wang, Li; Liu, Aibin; Yu, Guangsuo

2013-11-01

Co-pyrolysis behaviors of saw dust (SD) and Shenfu bituminous coal (SF) were studied in a drop tube furnace and a fixed bed reactor at different temperatures respectively. Six different biomass/coal ratios (B:C) were used. Compared the results with the calculated value obtained by the additional behavior, CO volume yields were lower while H2, CH4, CO2, volume yields were higher. Blend char yields had a good agreement with the calculated values, and their structures remained similar with SD and SF char's. Synergy effect occurred in gaseous phase, which was mainly caused by the secondary reactions. Compared the blend char yields in the drop tube furnace with those in the fixed bed reactor, the results showed the contacting way of biomass and coal particles had little influence on char yield in co-pyrolysis process. The reactivity index of blend char achieved the minimum at B:C=40:60 and the maximum at B:C=80:20. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of co-pyrolysis petrochemical wastewater sludge with lignite in a thermogravimetric analyzer and a packed-bed reactor: Pyrolysis characteristics, kinetics, and products analysis.

PubMed

Mu, Lin; Chen, Jianbiao; Yao, Pikai; Zhou, Dapeng; Zhao, Liang; Yin, Hongchao

2016-12-01

Co-pyrolysis characteristics of petrochemical wastewater sludge and Huolinhe lignite were investigated using thermogravimetric analyzer and packed-bed reactor coupled with Fourier transform infrared spectrometer and gas chromatography. The pyrolysis characteristics of the blends at various sludge blending ratios were compared with those of the individual materials. Thermogravimetric experiments showed that the interactions between the blends were beneficial to generate more residues. In packed-bed reactor, synergetic effects promoted the release of gas products and left less liquid and solid products than those calculated by additive manner. Fourier transform infrared spectrometer analysis showed that main functional groups in chars gradually disappeared with pyrolysis temperatures increasing, and H 2 O, CH 4 , CO, and CO 2 appeared in volatiles during pyrolysis. Gas compositions analysis indicated that, the yields of H 2 and CO clearly increased as the pyrolysis temperature and sludge blending ratio increasing, while the changes of CH 4 and CO 2 yields were relatively complex. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigation of Anaerobic Fluidized Bed Reactor/ Aerobic Moving Bed Bio Reactor (AFBR/MMBR) System for Treatment of Currant Wastewater

PubMed Central

JAFARI, Jalil; MESDAGHINIA, Alireza; NABIZADEH, Ramin; FARROKHI, Mehrdad; MAHVI, Amir Hossein

2013-01-01

Background: Anaerobic treatment methods are more suitable for the treatment of concentrated wastewater streams, offer lower operating costs, the production of usable biogas product. The aim of this study was to investigate the performance of an Anaerobic Fluidized Bed Reactor (AFBR)-Aerobic Moving Bed Bio Reactor (MBBR) in series arrangement to treat Currant wastewater. Methods: The bed materials of AFBR were cylindrical particles made of PVC with a diameter of 2–2.3 mm, particle density of 1250 kg/m3. The volume of all bed materials was 1.7 liter which expanded to 2.46 liters in fluidized situation. In MBBR, support media was composed of 1.5 liters Bee-Cell 2000 having porosity of 87% and specific surface area of 650m2/m3. Results: When system operated at 35 ºC, chemical oxygen demand (COD) removal efficiencies were achieved to 98% and 81.6% for organic loading rates (OLR) of 9.4 and 24.2 g COD/l.d, and hydraulic retention times (HRT) of 48 and 18 h, in average COD concentration feeding of 18.4 g/l, respectively. Conclusion: The contribution of AFBR in total COD removal efficiency at an organic loading rate (OLR) of 9.4 g COD/l.d was 95%, and gradually decreased to 76.5% in OLR of 24.2 g COD/l.d. Also with increasing in organic loading rate the contribution of aerobic reactor in removing COD gradually decreased. In this system, the anaerobic reactor played the most important role in the removal of COD, and the aerobic MBBR was actually needed to polish the anaerobic treated wastewater. PMID:26056640

Circulating moving bed system for CO.sub.2 separation, and method of same

DOEpatents

Elliott, Jeannine Elizabeth; Copeland, Robert James

2016-12-27

A circulating moving bed and process for separating a carbon dioxide from a gas stream is disclosed. The circulating moving bed can include an adsorption reactor and a desorption reactor, and a sorbent that moves through the two reactors. The sorbent can enter the adsorptive reactor and one end and move to an exit point distal to its entry point, while a CO.sub.2 feed stream can enter near the distal point and move countercurrently through the sorbent to exit at a position near the entry point of the sorbent. The sorbent can adsorb the CO.sub.2 by concentration swing adsorption and adsorptive displacement. The sorbent can then transfer to a regeneration reactor and can move countercurrently against a flow of steam through the regeneration reactor. The sorbent can be regenerated and the carbon dioxide recaptured by desorbing the carbon dioxide from the sorbent using concentration swing desorption and desorptive displacement with steam.

Steam reforming of heptane in a fluidized bed membrane reactor

NASA Astrophysics Data System (ADS)

Rakib, Mohammad A.; Grace, John R.; Lim, C. Jim; Elnashaie, Said S. E. H.

n-Heptane served as a model compound to study steam reforming of naphtha as an alternative feedstock to natural gas for production of pure hydrogen in a fluidized bed membrane reactor. Selective removal of hydrogen using Pd 77Ag 23 membrane panels shifted the equilibrium-limited reactions to greater conversion of the hydrocarbons and lower yields of methane, an intermediate product. Experiments were conducted with no membranes, with one membrane panel, and with six panels along the height of the reactor to understand the performance improvement due to hydrogen removal in a reactor where catalyst particles were fluidized. Results indicate that a fluidized bed membrane reactor (FBMR) can provide a compact reformer for pure hydrogen production from a liquid hydrocarbon feedstock at moderate temperatures (475-550 °C). Under the experimental conditions investigated, the maximum achieved yield of pure hydrogen was 14.7 moles of pure hydrogen per mole of heptane fed.

Pd-Ag Membrane Coupled to a Two-Zone Fluidized Bed Reactor (TZFBR) for Propane Dehydrogenation on a Pt-Sn/MgAl2O4 Catalyst

PubMed Central

Medrano, José-Antonio; Julián, Ignacio; Herguido, Javier; Menéndez, Miguel

2013-01-01

Several reactor configurations have been tested for catalytic propane dehydrogenation employing Pt-Sn/MgAl2O4 as a catalyst. Pd-Ag alloy membranes coupled to the multifunctional Two-Zone Fluidized Bed Reactor (TZFBR) provide an improvement in propane conversion by hydrogen removal from the reaction bed through the inorganic membrane in addition to in situ catalyst regeneration. Twofold process intensification is thereby achieved when compared to the use of traditional fluidized bed reactors (FBR), where coke formation and thermodynamic equilibrium represent important process limitations. Experiments were carried out at 500–575 °C and with catalyst mass to molar flow of fed propane ratios between 15.1 and 35.2 g min mmol−1, employing three different reactor configurations: FBR, TZFBR and TZFBR + Membrane (TZFBR + MB). The results in the FBR showed catalyst deactivation, which was faster at high temperatures. In contrast, by employing the TZFBR with the optimum regenerative agent flow (diluted oxygen), the process activity was sustained throughout the time on stream. The TZFBR + MB showed promising results in catalytic propane dehydrogenation, displacing the reaction towards higher propylene production and giving the best results among the different reactor configurations studied. Furthermore, the results obtained in this study were better than those reported on conventional reactors. PMID:24958620

Analysis of granular flow in a pebble-bed nuclear reactor.

PubMed

Rycroft, Chris H; Grest, Gary S; Landry, James W; Bazant, Martin Z

2006-08-01

Pebble-bed nuclear reactor technology, which is currently being revived around the world, raises fundamental questions about dense granular flow in silos. A typical reactor core is composed of graphite fuel pebbles, which drain very slowly in a continuous refueling process. Pebble flow is poorly understood and not easily accessible to experiments, and yet it has a major impact on reactor physics. To address this problem, we perform full-scale, discrete-element simulations in realistic geometries, with up to 440,000 frictional, viscoelastic 6-cm-diam spheres draining in a cylindrical vessel of diameter 3.5m and height 10 m with bottom funnels angled at 30 degrees or 60 degrees. We also simulate a bidisperse core with a dynamic central column of smaller graphite moderator pebbles and show that little mixing occurs down to a 1:2 diameter ratio. We analyze the mean velocity, diffusion and mixing, local ordering and porosity (from Voronoi volumes), the residence-time distribution, and the effects of wall friction and discuss implications for reactor design and the basic physics of granular flow.

Improved hydrocracker temperature control: Mobil quench zone technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarli, M.S.; McGovern, S.J.; Lewis, D.W.

1993-01-01

Hydrocracking is a well established process in the oil refining industry. There are over 2.7 million barrels of installed capacity world-wide. The hydrocracking process comprises several families of highly exothermic reactions and the total adiabatic temperature rise can easily exceed 200 F. Reactor temperature control is therefore very important. Hydrocracking reactors are typically constructed with multiple catalyst beds in series. Cold recycle gas is usually injected between the catalyst beds to quench the reactions, thereby controlling overall temperature rise. The design of this quench zone is the key to good reactor temperature control, particularly when processing poorer quality, i.e., highermore » heat release, feeds. Mobil Research and Development Corporation (MRDC) has developed a robust and very effective quench zone technology (QZT) package, which is now being licensed to the industry for hydrocracking applications.« less

Reduction of precursors of chlorination by-products in drinking water using fluidized-bed biofilm reactor at low temperature.

PubMed

Xie, Shu-Guang; Wen, Dong-Hui; Shi, Dong-Wen; Tang, Xiao-Yan

2006-10-01

To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM) formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3 degrees C, however, it could quickly rise to over 50% above 3degrees C. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.

Full scale fluidized bed anaerobic reactor for domestic wastewater treatment: performance, sludge production and biofilm.

PubMed

Mendonça, N M; Niciura, C L; Gianotti, E P; Campos, J R

2004-01-01

This paper describes the performance, sludge production and biofilm characteristics of a full scale fluidized bed anaerobic reactor (32 m3) for domestic wastewater treatment. The reactor was operated with 10.5 m x h(-1) upflow velocity, 3.2 h hydraulic retention time, and recirculation ratio of 0.85 and it presented removal efficiencies of 71+/-8% of COD and 77+/-14% of TSS. During the apparent steady-state period, specific sludge production and sludge age in the reactor were (0.116+/-0.033) kgVSS. kgCOD(-1) and (12+/-5)d, respectively. Biofilm formed in the reactor presented two different patterns: one of them at the beginning of the colonization and the other of mature biofilm. These different colonization patterns are due to bed stratification in the reactor, caused by the difference in local-energy dissipation rates along the reactor's height, and density, shape, etc. of the bioparticles. The biofilm population is formed mainly of syntrophic consortia among sulfate reducing bacteria, methanogenic archaea such as Methanobacterium and Methanosaeta-like cells.

TREATMENT OF VOCS IN HIGH STRENGTH WASTES USING AN ANAEROBIC EXPANDED-BED GAS REACTOR

EPA Science Inventory

The potential of the expanded-bed granular activated carbon (GAC) anaerobic reactor in treating a high strength waste containing RCRA volatile organic compounds (VOCs) was studied. A total of six VOCs, methylene chloride, chlorobenzene, carbon tetrachloride, chloroform, toluene ...

ANAEROBIC/AEROBIC BIODEGRADATION OF PENTACHLOROPHENOL USING GAC FLUIDIXED BED REACTORS: OPTIMIZATION OF THE EMPTY BED CONTACT TIME

EPA Science Inventory

An integrated reactor system has been developed to remediate pentachlorophenol (PCP) containing wastes using sequential anaerobic and aerobic biodegradation. Anaerobically, PCP was degraded to approximately equimolar concentrations (>99%) of chlorophenol (CP) in a granular activa...

Additive Manufacturing of Catalyst Substrates for Steam-Methane Reforming

NASA Astrophysics Data System (ADS)

Kramer, Michelle; McKelvie, Millie; Watson, Matthew

2018-01-01

Steam-methane reforming is a highly endothermic reaction, which is carried out at temperatures up to 1100 °C and pressures up to 3000 kPa, typically with a Ni-based catalyst distributed over a substrate of discrete alumina pellets or beads. Standard pellet geometries (spheres, hollow cylinders) limit the degree of mass transfer between gaseous reactants and catalyst. Further, heat is supplied to the exterior of the reactor wall, and heat transfer is limited due to the nature of point contacts between the reactor wall and the substrate pellets. This limits the degree to which the process can be intensified, as well as limiting the diameter of the reactor wall. Additive manufacturing now gives us the capability to design structures with tailored heat and mass transfer properties, not only within the packed bed of the reactor, but also at the interface between the reactor wall and the packed bed. In this work, the use of additive manufacturing to produce monolithic-structured catalyst substrate models, made from acrylonitrile-butadiene-styrene, with enhanced conductive heat transfer is described. By integrating the reactor wall into the catalyst substrate structure, the effective thermal conductivity increased by 34% from 0.122 to 0.164 W/(m K).

Design and fabrication of a fixed-bed batch type pyrolysis reactor for pilot scale pyrolytic oil production in Bangladesh

NASA Astrophysics Data System (ADS)

Aziz, Mohammad Abdul; Al-khulaidi, Rami Ali; Rashid, MM; Islam, M. R.; Rashid, MAN

2017-03-01

In this research, a development and performance test of a fixed-bed batch type pyrolysis reactor for pilot scale pyrolysis oil production was successfully completed. The characteristics of the pyrolysis oil were compared to other experimental results. A solid horizontal condenser, a burner for furnace heating and a reactor shield were designed. Due to the pilot scale pyrolytic oil production encountered numerous problems during the plant’s operation. This fixed-bed batch type pyrolysis reactor method will demonstrate the energy saving concept of solid waste tire by creating energy stability. From this experiment, product yields (wt. %) for liquid or pyrolytic oil were 49%, char 38.3 % and pyrolytic gas 12.7% with an operation running time of 185 minutes.

Combination of upflow anaerobic sludge blanket (UASB) reactor and partial nitritation/anammox moving bed biofilm reactor (MBBR) for municipal wastewater treatment.

PubMed

Malovanyy, Andriy; Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta

2015-03-01

In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5months period of transition from reject water to mainstream wastewater followed by a 16months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

Continuous succinic acid fermentation by Actinobacillus succinogenes in a packed-bed biofilm reactor.

PubMed

Ferone, Mariateresa; Raganati, Francesca; Ercole, Alessia; Olivieri, Giuseppe; Salatino, Piero; Marzocchella, Antonio

2018-01-01

Succinic acid is one of the most interesting platform chemicals that can be produced in a biorefinery approach. In this study, continuous succinic acid production by Actinobacillus succinogenes fermentation in a packed-bed biofilm reactor (PBBR) was investigated. The effects of the operating conditions tested, dilution rate (D), and medium composition (mixture of glucose, xylose, and arabinose-that simulate the composition of a lignocellulosic hydrolysate)-on the PBBR performances were investigated. The maximum succinic acid productivity of 35.0 g L -1  h -1 and the maximum SA concentration were achieved at a D  = 1.9 h -1 . The effect of HMF and furfural on succinic acid production was also investigated. HMF resulted to reduce succinic acid production by 22.6%, while furfural caused a reduction of 16% in SA production at the same dilution rate. Succinic acid production by A. succinogenes fermentation in a packed-bed reactor (PBBR) was successfully carried out for more than 5 months. The optimal results were obtained at the dilution rate 0.5 h -1 : 43.0 g L -1 of succinic acid were produced, glucose conversion was 88%; and the volumetric productivity was 22 g L -1  h -1 .

Optimization of lipase-catalyzed biodiesel by isopropanolysis in a continuous packed-bed reactor using response surface methodology.

PubMed

Chang, Cheng; Chen, Jiann-Hwa; Chang, Chieh-Ming J; Wu, Tsung-Ta; Shieh, Chwen-Jen

2009-10-31

Isopropanolysis reactions were performed using triglycerides with immobilized lipase in a solvent-free environment. This study modeled the degree of isopropanolysis of soybean oil in a continuous packed-bed reactor when Novozym 435 was used as the biocatalyst. Response surface methodology (RSM) and three-level-three-factor Box-Behnken design were employed to evaluate the effects of synthesis parameters, reaction temperature ( degrees C), flow rate (mL/min) and substrate molar ratio of isopropanol to soybean oil, on the percentage molar conversion of biodiesel by transesterification. The results show that flow rate and temperature have a significant effect on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions for synthesis were as follows: flow rate 0.1 mL/min, temperature 51.5 degrees C and substrate molar ratio 1:4.14. The predicted value was 76.62+/-1.52% and actual experimental value was 75.62+/-0.81% molar conversion. Moreover, continuous enzymatic process for seven days did not show any appreciable decrease in the percent of molar conversion (75%). This work demonstrates the applicability of lipase catalysis to prepare isopropyl esters by transesterification in solvent-free system with a continuous packed-bed reactor for industrial production.

Evaluation of Selected Chemical Processes for Production of Low-cost Silicon, Phase 3. [using a fluidized bed reactor

NASA Technical Reports Server (NTRS)

Blocher, J. M., Jr.; Browning, M. F.

1979-01-01

The construction and operation of an experimental process system development unit (EPSDU) for the production of granular semiconductor grade silicon by the zinc vapor reduction of silicon tetrachloride in a fluidized bed of seed particles is presented. The construction of the process development unit (PDU) is reported. The PDU consists of four critical units of the EPSDU: the fluidized bed reactor, the reactor by product condenser, the zinc vaporizer, and the electrolytic cell. An experimental wetted wall condenser and its operation are described. Procedures are established for safe handling of SiCl4 leaks and spills from the EPSDU and PDU.

Performance and stability of an expanded granular sludge bed reactor modified with zeolite addition subjected to step increases of organic loading rate (OLR) and to organic shock load (OSL).

PubMed

Pérez-Pérez, T; Pereda-Reyes, I; Pozzi, E; Oliva-Merencio, D; Zaiat, M

2018-01-01

This paper shows the effect of organic shock loads (OSLs) on the anaerobic digestion (AD) of synthetic swine wastewater using an expanded granular sludge bed (EGSB) reactor modified with zeolite. Two reactors (R1 and R2), each with an effective volume of 3.04 L, were operated for 180 days at a controlled temperature of 30 °C and hydraulic retention time of 12 h. In the case of R2, 120 g of zeolite was added. The reactors were operated with an up-flow velocity of 6 m/h. The evolution of pH, total Kjeldahl nitrogen, chemical oxygen demand (COD) and volatile fatty acids (VFAs) was monitored during the AD process with OSL and increases in the organic loading rate (OLR). In addition, the microbial composition and changes in the structure of the bacterial and archaeal communities were assessed. The principal results demonstrate that the presence of zeolite in an EGSB reactor provides a more stable process at higher OLRs and after applying OSL, based on both COD and VFA accumulation, which presented with significant differences compared to the control. Denaturing gradient gel electrophoresis band profiles indicated differences in the populations of Bacteria and Archaea between the R1 and R2 reactors, attributed to the presence of zeolite.

Improvements in Production of Single-Walled Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Balzano, Leandro; Resasco, Daniel E.

2009-01-01

A continuing program of research and development has been directed toward improvement of a prior batch process in which single-walled carbon nanotubes are formed by catalytic disproportionation of carbon monoxide in a fluidized-bed reactor. The overall effect of the improvements has been to make progress toward converting the process from a batch mode to a continuous mode and to scaling of production to larger quantities. Efforts have also been made to optimize associated purification and dispersion post processes to make them effective at large scales and to investigate means of incorporating the purified products into composite materials. The ultimate purpose of the program is to enable the production of high-quality single-walled carbon nanotubes in quantities large enough and at costs low enough to foster the further development of practical applications. The fluidized bed used in this process contains mixed-metal catalyst particles. The choice of the catalyst and the operating conditions is such that the yield of single-walled carbon nanotubes, relative to all forms of carbon (including carbon fibers, multi-walled carbon nanotubes, and graphite) produced in the disproportionation reaction is more than 90 weight percent. After the reaction, the nanotubes are dispersed in various solvents in preparation for end use, which typically involves blending into a plastic, ceramic, or other matrix to form a composite material. Notwithstanding the batch nature of the unmodified prior fluidized-bed process, the fluidized-bed reactor operates in a continuous mode during the process. The operation is almost entirely automated, utilizing mass flow controllers, a control computer running software specific to the process, and other equipment. Moreover, an important inherent advantage of fluidized- bed reactors in general is that solid particles can be added to and removed from fluidized beds during operation. For these reasons, the process and equipment were amenable to modification for conversion from batch to continuous production.

Method and apparatus for chemically altering fluids in continuous flow

DOEpatents

Heath, W.O.; Virden, J.W. Jr.; Richardson, R.L.; Bergsman, T.M.

1993-10-19

The present invention relates to a continuous flow fluid reactor for chemically altering fluids. The reactor operates on standard frequency (50 to 60 Hz) electricity. The fluid reactor contains particles that are energized by the electricity to form a corona throughout the volume of the reactor and subsequently a non-equilibrium plasma that interacts with the fluid. Particles may form a fixed bed or a fluid bed. Electricity may be provided through electrodes or through an inductive coil. Fluids include gases containing exhaust products and organic fuels requiring oxidation. 4 figures.

Method and apparatus for chemically altering fluids in continuous flow

DOEpatents

Heath, William O.; Virden, Jr., Judson W.; Richardson, R. L.; Bergsman, Theresa M.

1993-01-01

The present invention relates to a continuous flow fluid reactor for chemically altering fluids. The reactor operates on standard frequency (50 to 60 Hz) electricity. The fluid reactor contains particles that are energized by the electricity to form a corona throughout the volume of the reactor and subsequently a non-equilibrium plasma that interacts with the fluid. Particles may form a fixed bed or a fluid bed. Electricity may be provided through electrodes or through an inductive coil. Fluids include gases containing exhaust products and organic fuels requiring oxidation.

Modeling a Packed Bed Reactor Utilizing the Sabatier Process

NASA Technical Reports Server (NTRS)

Shah, Malay G.; Meier, Anne J.; Hintze, Paul E.

2017-01-01

A numerical model is being developed using Python which characterizes the conversion and temperature profiles of a packed bed reactor (PBR) that utilizes the Sabatier process; the reaction produces methane and water from carbon dioxide and hydrogen. While the specific kinetics of the Sabatier reaction on the RuAl2O3 catalyst pellets are unknown, an empirical reaction rate equation1 is used for the overall reaction. As this reaction is highly exothermic, proper thermal control is of the utmost importance to ensure maximum conversion and to avoid reactor runaway. It is therefore necessary to determine what wall temperature profile will ensure safe and efficient operation of the reactor. This wall temperature will be maintained by active thermal controls on the outer surface of the reactor. Two cylindrical PBRs are currently being tested experimentally and will be used for validation of the Python model. They are similar in design except one of them is larger and incorporates a preheat loop by feeding the reactant gas through a pipe along the center of the catalyst bed. The further complexity of adding a preheat pipe to the model to mimic the larger reactor is yet to be implemented and validated; preliminary validation is done using the smaller PBR with no reactant preheating. When mapping experimental values of the wall temperature from the smaller PBR into the Python model, a good approximation of the total conversion and temperature profile has been achieved. A separate CFD model incorporates more complex three-dimensional effects by including the solid catalyst pellets within the domain. The goal is to improve the Python model to the point where the results of other reactor geometry can be reasonably predicted relatively quickly when compared to the much more computationally expensive CFD approach. Once a reactor size is narrowed down using the Python approach, CFD will be used to generate a more thorough prediction of the reactors performance.

Methane production by attached film

DOEpatents

Jewell, William J.

1981-01-01

A method for purifying wastewater of biodegradable organics by converting the organics to methane and carbon dioxide gases is disclosed, characterized by the use of an anaerobic attached film expanded bed reactor for the reaction process. Dilute organic waste material is initially seeded with a heterogeneous anaerobic bacteria population including a methane-producing bacteria. The seeded organic waste material is introduced into the bottom of the expanded bed reactor which includes a particulate support media coated with a polysaccharide film. A low-velocity upward flow of the organic waste material is established through the bed during which the attached bacterial film reacts with the organic material to produce methane and carbon dioxide gases, purified water, and a small amount of residual effluent material. The residual effluent material is filtered by the film as it flows upwardly through the reactor bed. In a preferred embodiment, partially treated effluent material is recycled from the top of the bed to the bottom of the bed for further treatment. The methane and carbon dioxide gases are then separated from the residual effluent material and purified water.

Reactor for fluidized bed silane decomposition

NASA Technical Reports Server (NTRS)

Iya, Sridhar K. (Inventor)

1989-01-01

An improved heated fluidized bed reactor and method for the production of high purity polycrystalline silicon by silane pyrolysis wherein silicon seed particles are heated in an upper heating zone of the reactor and admixed with particles in a lower zone, in which zone a silane-containing gas stream, having passed through a lower cooled gas distribution zone not conducive to silane pyrolysis, contacts the heated seed particles whereon the silane is heterogeneously reduced to silicon.

Preliminary Safeguards Assessment for the Pebble-Bed Fluoride High-Temperature Reactor (PB-FHR) Concept

DOE Office of Scientific and Technical Information (OSTI.GOV)

Disser, Jay; Arthur, Edward; Lambert, Janine

2016-09-01

This report examines a preliminary design for a pebble bed fluoride salt-cooled high temperature reactor (PB-FHR) concept, assessing it from an international safeguards perspective. Safeguards features are defined, in a preliminary fashion, and suggestions are made for addressing further nuclear materials accountancy needs.

APPARATUS FOR SHORT TIME MEASUREMENTS IN A FIXED-BED, GAS/SOLID REACTOR

EPA Science Inventory

An apparatus for exposure of a solid to reactive process gas is described which makes possible short time (≥ 0.3 to 15 s) exposures in a fixed-bed reactor. Operating conditions for differential reaction with respect to the gas concentration and rapid quench for arresting hi...

ANALYSIS OF AN AEROBIC FLUIDIZED BED REACTOR DEGRADING MTBE AND BTEX AT REDUCED EBCTS

EPA Science Inventory

The purpose of this study was to investigate the biodegradation of MTBE and BTEX using a fluidized bed reactor (FBR) with granular activated carbon (GAC) as a biological attachment medium. Batch experiments were run to analyze the MTBE and TBA degradation kinetics of the culture ...

The effect of pH control and 'hydraulic flush' on hydrolysis and Volatile Fatty Acids (VFA) production and profile in anaerobic leach bed reactors digesting a high solids content substrate.

PubMed

Cysneiros, Denise; Banks, Charles J; Heaven, Sonia; Karatzas, Kimon-Andreas G

2012-11-01

The effect of hydraulic flush and pH control on hydrolysis, Volatile Fatty Acids (VFA) production and profile in anaerobic leach bed reactors was investigated for the first time. Six reactors were operated under different regimes for two consecutive batches of 28days each. Buffering at pH ∼6.5 improved hydrolysis (Volatile Solid (VS) degradation) and VFA production by ∼50%. Butyric and acetic acid were dominant when reactors were buffered, while only butyric acid was produced at low pH. Hydraulic flush enhanced VS degradation and VFA production by ∼15% and ∼32%, respectively. Most Probable Number (MPN) of cellulolytic microorganisms indicated a wash out when hydraulic flush was applied, but pH control helped to counteract this. The highest VS degradation (∼89%), VFA yield (0.84kgCODkg(-1)VS(added)) and theoretical methane potential (0.37m(3)CH(4)kg(-1)VS(added)) were obtained when pH control and hydraulic flush were applied, and therefore, these conditions are recommended. Copyright © 2012 Elsevier Ltd. All rights reserved.

Heterogeneous decomposition of silane in a fixed bed reactor

NASA Technical Reports Server (NTRS)

Iya, S. K.; Flagella, R. N.; Dipaolo, F. S.

1982-01-01

Heterogeneous decomposition of silane in a fluidized bed offers an attractive route for the low-cost production of silicon for photovoltaic application. To obtain design data for a fluid bed silane pyrolysis reactor, deposition experiments were conducted in a small-scale fixed bed apparatus. Data on the decomposition mode, plating rate, and deposition morphology were obtained in the temperature range 600-900 C. Conditions favorable for heterogeneous decomposition with good deposition morphology were identified. The kinetic rate data showed the reaction to be first order with an activation energy of 38.8 kcal/mol, which agrees well with work done by others. The results are promising for the development of an economically attractive fluid bed process.

Desulfurizing Coal With an Alkali Treatment

NASA Technical Reports Server (NTRS)

Ravindram, M.; Kalvinskas, J. J.

1987-01-01

Experimental coal-desulfurization process uses alkalies and steam in fluidized-bed reactor. With highly volatile, high-sulfur bituminous coal, process removed 98 percent of pyritic sulfur and 47 percent of organic sulfur. Used in coal liquefaction and in production of clean solid fuels and synthetic liquid fuels. Nitrogen or steam flows through bed of coal in reactor. Alkalies react with sulfur, removing it from coal. Nitrogen flow fluidizes bed while heating or cooling; steam is fluidizing medium during reaction.

Comparison between several reactors with Trametes versicolor immobilized on lignocellulosic support for the continuous treatments of hospital wastewater.

PubMed

Torán, J; Blánquez, P; Caminal, G

2017-11-01

Hospital wastewater is a major source of pharmaceutically active compounds (PhACs), which are not all removed in conventional wastewater treatment plants. White rot fungi can degrade PhACs, but their application has been limited to non-sterile conditions due to the competition with other microorganisms for growth. In this study, immobilization of Trametes versicolor on different lignocellulosic supports was studied as strategy to ensure fungal survival under continuous treatment conditions. A fluidized bed reactor and a trickling packed-bed reactor with T. versicolor immobilized on pallet wood were employed for the removal of ibuprofen, ketoprofen and naproxen. Best results were obtained with the trickling packed-bed reactor, which operated for 49days with high removal values in real hospital wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development and performance of an alternative biofilter system.

PubMed

Lee, D H; Lau, A K; Pinder, K L

2001-01-01

Step tracer tests were carried out on lab-scale biofilters to determine the residence time distributions (RTDs) of gases passing through two types of biofilters: a standard biofilter with vertical gas flow and a modified biofilter with horizontal gas flow. Results were used to define the flow patterns in the reactors. "Non-ideal flow" indicates that the flow reactors did not behave like either type of ideal reactor: the perfectly stirred reactor [often called a "continuously stirred tank reactor" (CSTR)] or the plug-flow reactor. The horizontal biofilter with back-mixing was able to accommodate a shorter residence time without the usual requirement of greater biofilter surface area for increased biofiltration efficiency. Experimental results indicated that the first bed of the modified biofilter behaved like two CSTRs in series, while the second bed may be represented by two or three CSTRs in series. Because of the flow baffles used in the horizontal biofilter system, its performance was more similar to completely mixed systems, and hence, it could not be modeled as a plug-flow reactor. For the standard biofilter, the number of CSTRs was found to be between 2 and 9 depending on the airflow rate. In terms of NH3 removal efficiency and elimination capacity, the standard biofilter was not as good as the modified system; moreover, the second bed of the modified biofilter exhibited greater removal efficiency than the first bed. The elimination rate increased as biofilter load increased. An opposite trend was exhibited with respect to removal efficiency.

PEBBLE: a two-dimensional steady-state pebble bed reactor thermal hydraulics code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vondy, D.R.

1981-09-01

This report documents the local implementation of the PEBBLE code to treat the two-dimensional steady-state pebble bed reactor thermal hydraulics problem. This code is implemented as a module of a computation system used for reactor core history calculations. Given power density data, the geometric description in (RZ), and basic heat removal conditions and thermal properties, the coolant properties, flow conditions, and temperature distributions in the pebble fuel elements are predicted. The calculation is oriented to the continuous fueling, steady state condition with consideration of the effect of the high energy neutron flux exposure and temperature history on the thermal conductivity.more » The coolant flow conditions are calculated for the same geometry as used in the neutronics calculation, power density and fluence data being used directly, and temperature results are made available for subsequent use.« less

The slow and fast pyrolysis of cherry seed.

PubMed

Duman, Gozde; Okutucu, Cagdas; Ucar, Suat; Stahl, Ralph; Yanik, Jale

2011-01-01

The slow and fast pyrolysis of cherry seeds (CWS) and cherry seeds shells (CSS) was studied in fixed-bed and fluidized bed reactors at different pyrolysis temperatures. The effects of reactor type and temperature on the yields and composition of products were investigated. In the case of fast pyrolysis, the maximum bio-oil yield was found to be about 44 wt% at pyrolysis temperature of 500 °C for both CWS and CSS, whereas the bio yields were of 21 and 15 wt% obtained at 500 °C from slow pyrolysis of CWS and CSS, respectively. Both temperature and reactor type affected the composition of bio-oils. The results showed that bio-oils obtained from slow pyrolysis of CWS and CSS can be used as a fuel for combustion systems in industry and the bio-oil produced from fast pyrolysis can be evaluated as a chemical feedstock. Copyright © 2010 Elsevier Ltd. All rights reserved.

Waste tyre pyrolysis: modelling of a moving bed reactor.

PubMed

Aylón, E; Fernández-Colino, A; Murillo, R; Grasa, G; Navarro, M V; García, T; Mastral, A M

2010-12-01

This paper describes the development of a new model for waste tyre pyrolysis in a moving bed reactor. This model comprises three different sub-models: a kinetic sub-model that predicts solid conversion in terms of reaction time and temperature, a heat transfer sub-model that calculates the temperature profile inside the particle and the energy flux from the surroundings to the tyre particles and, finally, a hydrodynamic model that predicts the solid flow pattern inside the reactor. These three sub-models have been integrated in order to develop a comprehensive reactor model. Experimental results were obtained in a continuous moving bed reactor and used to validate model predictions, with good approximation achieved between the experimental and simulated results. In addition, a parametric study of the model was carried out, which showed that tyre particle heating is clearly faster than average particle residence time inside the reactor. Therefore, this fast particle heating together with fast reaction kinetics enables total solid conversion to be achieved in this system in accordance with the predictive model. Copyright © 2010 Elsevier Ltd. All rights reserved.

Biodegradation of endocrine disruptors in urban wastewater using Pleurotus ostreatus bioreactor.

PubMed

Křesinová, Zdena; Linhartová, Lucie; Filipová, Alena; Ezechiáš, Martin; Mašín, Pavel; Cajthaml, Tomáš

2018-07-25

The white rot fungus Pleurotus ostreatus HK 35, which is also an edible industrial mushroom commonly cultivated in farms, was tested in the degradation of typical representatives of endocrine disrupters (EDCs; bisphenol A, estrone, 17β-estradiol, estriol, 17α-ethinylestradiol, triclosan and 4-n-nonylphenol); its degradation efficiency under model laboratory conditions was greater than 90% within 12 days and better than that of another published strain P. ostreatus 3004. A spent mushroom substrate from a local farm was tested for its applicability in various batch and trickle-bed reactors in degrading EDCs in model fortified and real communal wastewater. The reactors were tested under various regimes including a pilot-scale trickle-bed reactor, which was finally tested at a wastewater treatment plant. The result revealed that the spent substrate is an efficient biodegradation agent, where the fungus was usually able to remove about 95% of EDCs together with suppression of the estrogenic activity of the sample. The results showed the fungus was able to operate in the presence of bacterial microflora in wastewater without any substantial negative effects on the degradation abilities. Finally, a pilot-scale trickle-bed reactor was installed in a wastewater treatment plant and successfully operated for 10days, where the bioreactor was able to remove more than 76% of EDCs present in the wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

High rate manure supernatant digestion.

PubMed

Bergland, Wenche Hennie; Dinamarca, Carlos; Toradzadegan, Mehrdad; Nordgård, Anna Synnøve Røstad; Bakke, Ingrid; Bakke, Rune

2015-06-01

The study shows that high rate anaerobic digestion may be an efficient way to obtain sustainable energy recovery from slurries such as pig manure. High process capacity and robustness to 5% daily load increases are observed in the 370 mL sludge bed AD reactors investigated. The supernatant from partly settled, stored pig manure was fed at rates giving hydraulic retention times, HRT, gradually decreased from 42 to 1.7 h imposing a maximum organic load of 400 g COD L(-1) reactor d(-1). The reactors reached a biogas production rate of 97 g COD L(-1) reactor d(-1) at the highest load at which process stress signs were apparent. The yield was ∼0.47 g COD methane g(-1) CODT feed at HRT above 17 h, gradually decreasing to 0.24 at the lowest HRT (0.166 NL CH4 g(-1) CODT feed decreasing to 0.086). Reactor pH was innately stable at 8.0 ± 0.1 at all HRTs with alkalinity between 9 and 11 g L(-1). The first stress symptom occurred as reduced methane yield when HRT dropped below 17 h. When HRT dropped below 4 h the propionate removal stopped. The yield from acetate removal was constant at 0.17 g COD acetate removed per g CODT substrate. This robust methanogenesis implies that pig manure supernatant, and probably other similar slurries, can be digested for methane production in compact and effective sludge bed reactors. Denaturing gradient gel electrophoresis (DGGE) analysis indicated a relatively fast adaptation of the microbial communities to manure and implies that non-adapted granular sludge can be used to start such sludge bed bioreactors. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Characterization of reactive CaCO 3 crystallization in a fluidized bed reactor as a central process of direct air capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burhenne, Luisa; Giacomin, Caroline; Follett, Trevor

A laboratory-scale, fluidized-bed pellet reactor (BPR) was used to investigate a CaCO 3 crystallization process for the recovery of CO 2 in a Direct Air Capture (DAC) process. The BPR performance was validated against data from a pilot-scale unit. Subsequently, the pellet growth under process-relevant conditions was studied over a period of 144 h. The experimental results with the BPR, containing a bed of pellets sized between 0.65 and 0.84 mm, have shown that a calcium retention of 80% can be achieved at a fluidization velocity of 60 m h -1 and a calcium loading rate of 3 mol hmore » -1. This result is consistent with calcium retention observed at pilot scale operation and hence, results from the BPR are considered representative for the pilot scale unit. Starting with a bed of pellets sized between 0.15 and 0.5 mm, the average pellet growth rate, G, at the reactor bottom increased from 8.1E-10 to 11E–10 m s -1 at the onset and decreased to 4.9E–10 m s -1 over the course of a 144 h test. The calcium retention over the course the test showed the same trend (initial increase and final decrease) as the pellet growth rate. A theoretical bed growth model was developed and validated against data from the pilot scale and benchtop pellet reactors. The model was used to calculate the bed porosity and total pellet surface area in each control volume. Lastly, the pellet surface area growth at the bottom of the reactor reproduced the pellet growth and retention data trends.« less

Characterization of reactive CaCO 3 crystallization in a fluidized bed reactor as a central process of direct air capture

DOE PAGES

Burhenne, Luisa; Giacomin, Caroline; Follett, Trevor; ...

2017-10-25

A laboratory-scale, fluidized-bed pellet reactor (BPR) was used to investigate a CaCO 3 crystallization process for the recovery of CO 2 in a Direct Air Capture (DAC) process. The BPR performance was validated against data from a pilot-scale unit. Subsequently, the pellet growth under process-relevant conditions was studied over a period of 144 h. The experimental results with the BPR, containing a bed of pellets sized between 0.65 and 0.84 mm, have shown that a calcium retention of 80% can be achieved at a fluidization velocity of 60 m h -1 and a calcium loading rate of 3 mol hmore » -1. This result is consistent with calcium retention observed at pilot scale operation and hence, results from the BPR are considered representative for the pilot scale unit. Starting with a bed of pellets sized between 0.15 and 0.5 mm, the average pellet growth rate, G, at the reactor bottom increased from 8.1E-10 to 11E–10 m s -1 at the onset and decreased to 4.9E–10 m s -1 over the course of a 144 h test. The calcium retention over the course the test showed the same trend (initial increase and final decrease) as the pellet growth rate. A theoretical bed growth model was developed and validated against data from the pilot scale and benchtop pellet reactors. The model was used to calculate the bed porosity and total pellet surface area in each control volume. Lastly, the pellet surface area growth at the bottom of the reactor reproduced the pellet growth and retention data trends.« less

Digestion performance and microbial community in full-scale methane fermentation of stillage from sweet potato-shochu production.

PubMed

Kobayashi, Tsutomu; Tang, Yueqin; Urakami, Toyoshi; Morimura, Shigeru; Kida, Kenji

2014-02-01

Sweet potato shochu is a traditional Japanese spirit produced mainly in the South Kyushu area in Japan. The amount of stillage reaches approximately 8 x 10(5) tons per year. Wastewater mainly containing stillage from the production of sweet potato-shochu was treated thermophilically in a full-scale treatment plant using fixed-bed reactors (8 reactors x 283 m3). Following the addition of Ni2+ and Co2+, the reactors have been stably operated for six years at a high chemical oxygen demand (COD) loading rate of 14 kg/(m3 x day). Analysis of coenzyme content and microbial communities indicated that similar microbial communities were present in the liquid phase and on the fiber carriers installed in reactors. Bacteria in the phyla Firmicutes as well as Bacteroidetes were dominant bacteria, and Methanosarcina thermophila as well as Methanothermobacter crinale were dominant methanogens in the reactors. This study reveals that stillage from sweet potato-shochu production can be treated effectively in a full-scale fixed-bed reactor under thermophilic conditions with the help of Ni2+ and Co2+. The high diversity of bacterial community and the coexistence of both aceticlastic and hydrogenotrophic methanogens contributed to the excellent fermentation performance.

DECONTAMINATION OF NEUTRON-IRRADIATED REACTOR FUEL

DOEpatents

Buyers, A.G.; Rosen, F.D.; Motta, E.E.

1959-12-22

A pyrometallurgical method of decontaminating neutronirradiated reactor fuel is presented. In accordance with the invention, neutron-irradiated reactor fuel may be decontaminated by countercurrently contacting the fuel with a bed of alkali and alkaine fluorides under an inert gas atmosphere and inductively melting the fuel and tracking the resulting descending molten fuel with induction heating as it passes through the bed. By this method, a large, continually fresh surface of salt is exposed to the descending molten fuel which enhances the efficiency of the scrubbing operation.

Particle bed reactor modeling

NASA Technical Reports Server (NTRS)

Sapyta, Joe; Reid, Hank; Walton, Lew

1993-01-01

The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

Feasibility of rotating fluidized bed reactor for rocket propulsion

NASA Technical Reports Server (NTRS)

Ludewig, H.; Manning, A. J.; Raseman, C. J.

1974-01-01

The rotating fluidized bed reactor concept is outlined, and its application to rocket propulsion is discussed. Experimental results obtained indicate that minimum fluidization correlations commonly in use for 1-g beds can also be applied to multiple-g beds. It was found that for a low thrust system (20,000 lbf) the fuel particle size and/or particle stress play a limiting role on performance. The superiority of U-233 as a fuel for this type of rocket engine is clearly demonstrated in the analysis. The maximum thrust/weight ratio for a 90,000N thrust engine was found to be approximately 65N/kg.

A dual purpose packed-bed reactor for biogas scrubbing and methane-dependent water quality improvement applying to a wastewater treatment system consisting of UASB reactor and trickling filter.

PubMed

Tanaka, Yasuo

2002-08-01

A wastewater treatment system employing a UASB reactor in temperate regions requires biogas as a heat source for the UASB reactor during low temperature seasons. In this case, removal of H2S in the biogas by means of a scrubber before burning is necessary in order to prevent the boilers from corroding. Heating of the UASB reactor is, however, unnecessary in a warm season, and the scrubber and biogas become useless. Methane-dependent water quality improvement using the scrubber and biogas would be one way to use them efficiently during the warm season. The possible dual-purpose use of a packed-bed reactor was examined, with one of its uses being the scrubbing of biogas during the cold season and the other being the methane-dependent improvement of effluent water quality during the warm season. A bench scale packed-bed filled with plastic latticed-ring media was installed in a livestock wastewater treatment plant consisting of a UASB reactor and a trickling filter for post-treatment. The packed-bed was operated with biogas flowing at a superficial velocity of 0.14-0.39 m h(-1) and the hydraulic loading of trickling filter effluent sprayed onto the media 9.4-26.1 m3 m2 day(-1). H2S in the biogas from the UASB reactor was reduced from 1,200-2,500 ppm to less than 2 ppm by the reactor. Methane-dependent water quality improvement was examined using a laboratory scale reactor to which methane and/or air was supplied from the bottom, while plant effluent was spread from the top of the reactor. When the mixture gas of methane and air (volume ratio 1:3) was added to the reactor, biofilm grew on the surface of the media. Accompanying this growth, ammonium and phosphate in the spread water decreased, probably due to assimilation by the methane-oxidizing bacteria. Though assimilation activity dropped after the accumulation of biomass, it could be reactivated by washing out the excess biomass. Periodical backwash at a rate of more than once a week seemed to efficiently maintain the removal activity. The dark brown color of the wastewater could be also reduced in concert with methane oxidation. It seemed that methane-oxidizing bacteria degraded color-causing compounds. These results suggest that the packed-bed reactor is useful for both H2S purification of biogas and methane-dependent effluent water quality improvement.

Solar heated fluidized bed gasification system

NASA Technical Reports Server (NTRS)

Qader, S. A. (Inventor)

1981-01-01

A solar-powered fluidized bed gasification system for gasifying carbonaceous material is presented. The system includes a solar gasifier which is heated by fluidizing gas and steam. Energy to heat the gas and steam is supplied by a high heat capacity refractory honeycomb which surrounds the fluid bed reactor zone. The high heat capacity refractory honeycomb is heated by solar energy focused on the honeycomb by solar concentrator through solar window. The fluid bed reaction zone is also heated directly and uniformly by thermal contact of the high heat capacity ceramic honeycomb with the walls of the fluidized bed reactor. Provisions are also made for recovering and recycling catalysts used in the gasification process. Back-up furnace is provided for start-up procedures and for supplying heat to the fluid bed reaction zone when adequate supplies of solar energy are not available.

Hydrogen sulfide removal from air by Acidithiobacillus thiooxidans in a trickle bed reactor.

PubMed

Ramirez, M; Gómez, J M; Cantero, D; Páca, J; Halecký, M; Kozliak, E I; Sobotka, M

2009-09-01

A strain of Acidithiobacillus thiooxidans immobilized in polyurethane foam was utilized for H(2)S removal in a bench-scale trickle-bed reactor, testing the limits of acidity and SO(4) (2-) accumulation. The use of this acidophilic strain resulted in remarkable stability in the performance of the system. The reactor maintained a >98-99 % H(2)S removal efficiency for c of up to 66 ppmv and empty bed residence time 98 % H(2)S was achieved under steady-state conditions, over the pH range of 0.44-7.30. Despite the accumulation of acidity and SO(4) (2-) (up to 97 g/L), the system operated without inhibition.

Influence of mass transfer resistance on overall nitrate removal rate in upflow sludge bed reactors.

PubMed

Ting, Wen-Huei; Huang, Ju-Sheng

2006-09-01

A kinetic model with intrinsic reaction kinetics and a simplified model with apparent reaction kinetics for denitrification in upflow sludge bed (USB) reactors were proposed. USB-reactor performance data with and without sludge wasting were also obtained for model verification. An independent batch study showed that the apparent kinetic constants k' did not differ from the intrinsic k but the apparent Ks' was significantly larger than the intrinsic Ks suggesting that the intra-granule mass transfer resistance can be modeled by changes in Ks. Calculations of the overall effectiveness factor, Thiele modulus, and Biot number combined with parametric sensitivity analysis showed that the influence of internal mass transfer resistance on the overall nitrate removal rate in USB reactors is more significant than the external mass transfer resistance. The simulated residual nitrate concentrations using the simplified model were in good agreement with the experimental data; the simulated results using the simplified model were also close to those using the kinetic model. Accordingly, the simplified model adequately described the overall nitrate removal rate and can be used for process design.

Preliminary Studies on Oleochemical Wastewater Treatment using Submerged Bed Biofilm Reactor (SBBR)

NASA Astrophysics Data System (ADS)

Ismail, Z.; Mahmood, N. A. N.; Ghafar, U. S. A.; Umor, N. A.; Muhammad, S. A. F.

2017-06-01

Wastewater discharge from the industry into water sources is one of the main reason for water pollution. The oleochemicals industry effluent produces high content of chemical oxygen demand (COD) with value between 6000-20,000 ppm. Effective treatment is required before wastewater effluent is discharged to environment. The aim of the study is to develop submerged bed biofilm reactor (SBBR) with packing materials in the cosmoball® carrier. Water quality such as chemical oxygen demands (COD), turbidity and pH were analysed. The result shows that the initial COD of 6000 ppm was reduced below 200 ppm. The optimum conditions for SBBR were obtained when green sponges used as packing material in cosmoball® effluent flowrate set at 100 mL/min; 1:1 ratio of cosmoball® volume to reactor volume and 1:1 ratio of active sludge (mixed culture) volume to reactor volume. Turbidity and pH were recorded with 9.0 NTU and 7.0 respectively, which indicated that SBBR is feasible as an alternative for conventional biological treatment in oleochemical industry.

Heat-transfer characteristics of flowing and stationary particle-bed-type fusion-reactor blankets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nietert, R.E.

1983-02-01

The following five appendices are included: (1) physical properties of materials, (2) thermal entrance length Nusselt number variations, (3) stationary particle bed temperature variations, (4) falling bed experimental data and calculations, and (5) stationary bed experimental data and calculations. (MOW)

Ceramic membrane microfilter as an immobilized enzyme reactor.

PubMed

Harrington, T J; Gainer, J L; Kirwan, D J

1992-10-01

This study investigated the use of a ceramic microfilter as an immobilized enzyme reactor. In this type of reactor, the substrate solution permeates the ceramic membrane and reacts with an enzyme that has been immobilized within its porous interior. The objective of this study was to examine the effect of permeation rate on the observed kinetic parameters for the immobilized enzyme in order to assess possible mass transfer influences or shear effects. Kinetic parameters were found to be independent of flow rate for immobilized penicillinase and lactate dehydrogenase. Therefore, neither mass transfer nor shear effects were observed for enzymes immobilized within the ceramic membrane. Both the residence time and the conversion in the microfilter reactor could be controlled simply by regulating the transmembrane pressure drop. This study suggests that a ceramic microfilter reactor can be a desirable alternative to a packed bed of porous particles, especially when an immobilized enzyme has high activity and a low Michaelis constant.

Limitations for heavy metal release during thermo-chemical treatment of sewage sludge ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowak, Benedikt, E-mail: benedikt.nowak@tuwien.ac.at; Perutka, Libor; Aschenbrenner, Philipp

2011-06-15

Phosphate recycling from sewage sludge can be achieved by heavy metal removal from sewage sludge ash (SSA) producing a fertilizer product: mixing SSA with chloride and treating this mixture (eventually after granulation) in a rotary kiln at 1000 {+-} 100 deg. C leads to the formation of volatile heavy metal compounds that evaporate and to P-phases with high bio-availability. Due to economical and ecological reasons, it is necessary to reduce the energy consumption of this technology. Generally, fluidized bed reactors are characterized by high heat and mass transfer and thus promise the saving of energy. Therefore, a rotary reactor andmore » a fluidized bed reactor (both laboratory-scale and operated in batch mode) are used for the treatment of granulates containing SSA and CaCl{sub 2}. Treatment temperature, residence time and - in case of the fluidized bed reactor - superficial velocity are varied between 800 and 900 deg. C, 10 and 30 min and 3.4 and 4.6 m s{sup -1}. Cd and Pb can be removed well (>95 %) in all experiments. Cu removal ranges from 25% to 84%, for Zn 75-90% are realized. The amount of heavy metals removed increases with increasing temperature and residence time which is most pronounced for Cu. In the pellet, three major reactions occur: formation of HCl and Cl{sub 2} from CaCl{sub 2}; diffusion and reaction of these gases with heavy metal compounds; side reactions from heavy metal compounds with matrix material. Although, heat and mass transfer are higher in the fluidized bed reactor, Pb and Zn removal is slightly better in the rotary reactor. This is due the accelerated migration of formed HCl and Cl{sub 2} out of the pellets into the reactor atmosphere. Cu is apparently limited by the diffusion of its chloride thus the removal is higher in the fluidized bed unit.« less

Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

PubMed Central

Qureshi, Nasib; Annous, Bassam A; Ezeji, Thaddeus C; Karcher, Patrick; Maddox, Ian S

2005-01-01

This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent) or form flocs/aggregates (also called granules) without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL-1 can be achieved. The reactor configurations can be as simple as a batch reactor, continuous stirred tank reactor (CSTR), packed bed reactor (PBR), fluidized bed reactor (FBR), airlift reactor (ALR), upflow anaerobic sludge blanket (UASB) reactor, or any other suitable configuration. In UASB granular biofilm particles are used. This article demonstrates that reactor productivities in these reactors have been superior to any other reactor types. This article describes production of ethanol, butanol, lactic acid, acetic acid/vinegar, succinic acid, and fumaric acid in addition to wastewater treatment in the biofilm reactors. As the title suggests, biofilm reactors have high potential to be employed in biotechnology/bioconversion industry for viable economic reasons. In this article, various reactor types have been compared for the above bioconversion processes. PMID:16122390

Acetone-butanol-ethanol (ABE) fermentation in an immobilized cell trickle bed reactor.

PubMed

Park, C H; Okos, M R; Wankat, P C

1989-06-05

Acetone-butanol-ethanol (ABE) fermentation was successfully carried out in an immobilized cell trickle bed reactor. The reactor was composed of two serial columns packed with Clostridium acetobutylicum ATCC 824 entrapped on the surface of natural sponge segments at a cell loading in the range of 2.03-5.56 g dry cells/g sponge. The average cell loading was 3.58 g dry cells/g sponge. Batch experiments indicated that a critical pH above 4.2 is necessary for the initiation of cell growth. One of the media used during continuous experiments consisted of a salt mixture alone and the other a nutrient medium containing a salt mixture with yeast extract and peptone. Effluent pH was controlled by supplying various fractions of the two different types of media. A nutrient medium fraction above 0.6 was crucial for successful fermentation in a trickle bed reactor. The nutrient medium fraction is the ratio of the volume of the nutrient medium to the total volume of nutrient plus salt medium. Supplying nutrient medium to both columns continuously was an effective way to meet both pH and nutrient requirement. A 257-mL reactor could ferment 45 g/L glucose from an initial concentration of 60 g/L glucose at a rate of 70 mL/h. Butanol, acetone, and ethanol concentrations were 8.82, 5.22, and 1.45 g/L, respectively, with a butanol and total solvent yield of 19.4 and 34.1 wt %. Solvent productivity in an immobilized cell trickle bed reactor was 4.2 g/L h, which was 10 times higher than that obtained in a batch fermentation using free cells and 2.76 times higher than that of an immobilized CSTR. If the nutrient medium fraction was below 0.6 and the pH was below 4.2, the system degenerated. Oxygen also contributed to the system degeneration. Upon degeneration, glucose consumption and solvent yield decreased to 30.9 g/L and 23.0 wt %, respectively. The yield of total liquid product (40.0 wt %) and butanol selectivity (60.0 wt %) remained almost constant. Once the cells were degenerated, they could not be recovered.

Microbial community dynamics and biogas production from manure fractions in sludge bed anaerobic digestion.

PubMed

Nordgård, A S R; Bergland, W H; Bakke, R; Vadstein, O; Østgaard, K; Bakke, I

2015-12-01

To elucidate how granular sludge inoculum and particle-rich organic loading affect the structure of the microbial communities and process performance in upflow anaerobic sludge bed (UASB) reactors. We investigated four reactors run on dairy manure filtrate and four on pig manure supernatant for three months achieving similar methane yields. The reactors fed with less particle rich pig manure stabilized faster and had highest capacity. Microbial community dynamics analysed by a PCR/denaturing gradient gel electrophoresis approach showed that influent was a major determinant for the composition of the reactor communities. Comparisons of pre- and non-adapted inoculum in the reactors run on pig manure supernatant showed that the community structure of the nonadapted inoculum adapted in approximately two months. Microbiota variance partitioning analysis revealed that running time, organic loading rate and inoculum together explained 26 and 31% of the variance in bacterial and archaeal communities respectively. The microbial communities of UASBs adapted to the reactor conditions in treatment of particle rich manure fractions, obtaining high capacity, especially on pig manure supernatant. These findings provide relevant insight into the microbial community dynamics in startup and operation of sludge bed reactors for methane production from slurry fractions, a major potential source of biogas. © 2015 The Society for Applied Microbiology.

Biological production of ethanol from coal. Task 4 report, Continuous reactor studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The production of ethanol from synthesis gas by the anaerobic bacterium C. ljungdahlii has been demonstrated in continuous stirred tank reactors (CSTRs), CSTRs with cell recycle and trickle bed reactors. Various liquid media were utilized in these studies including basal medium, basal media with 1/2 B-vitamins and no yeast extract and a medium specifically designed for the growth of C. ljungdahlii in the CSTR. Ethanol production was successful in each of the three reactor types, although trickle bed operation with C. ljungdahlii was not as good as with the stirred tank reactors. Operation in the CSTR with cell recycle wasmore » particularly promising, producing 47 g/L ethanol with only minor concentrations of the by-product acetate.« less

Fluidized bed coal desulfurization

NASA Technical Reports Server (NTRS)

Ravindram, M.

1983-01-01

Laboratory scale experiments were conducted on two high volatile bituminous coals in a bench scale batch fluidized bed reactor. Chemical pretreatment and posttreatment of coals were tried as a means of enhancing desulfurization. Sequential chlorination and dechlorination cum hydrodesulfurization under modest conditions relative to the water slurry process were found to result in substantial sulfur reductions of about 80%. Sulfur forms as well as proximate and ultimate analyses of the processed coals are included. These studies indicate that a fluidized bed reactor process has considerable potential for being developed into a simple and economic process for coal desulfurization.

Improving hydrolysis of food waste in a leach bed reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Browne, James D.; Allen, Eoin; Murphy, Jerry D., E-mail: jerry.murphy@ucc.ie

2013-11-15

Highlights: • This paper assesses leaching of food waste in a two phase digestion system. • Leaching is assessed with and without an upflow anaerobic sludge blanket (UASB). • Without the UASB, low pH reduces hydrolysis, while increased flows increase leaching. • Inclusion of the UASB increases pH to optimal levels and greatly improves leaching. • The optimal conditions are suggested as low flow with connection to the UASB. - Abstract: This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a lowmore » and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB.« less

Behavior of nitrogen removal in an aerobic sponge based moving bed biofilm reactor.

PubMed

Zhang, Xinbo; Song, Zi; Guo, Wenshan; Lu, Yanmin; Qi, Li; Wen, Haitao; Ngo, Huu Hao

2017-12-01

This study aims to investigate the behavior of nitrogen removal in an aerobic sponge based moving bed biofilm reactor by evaluating nitrification and denitrification rates of sponge biocarriers from three aerobic moving bed biofilm reactors (MBBRs) with filling ratios of 10% (R-10), 20% (R-20) and 30% (R-30). Results showed that the highest removal efficiencies of total nitrogen in three reactors were 84.5% (R-10), 93.6% (R-20) and 95.3% (R-30). Correspondingly, simultaneous nitrification and denitrification rate (SND) was 90.9%, 97.6% and 100%, respectively. Although R-20 had the highest attached-growth biomass (AGB) per gram of sponge compared to the other two reactors, R-30 showed the maximum ammonium oxidation rate (AOR) (2.1826±0.0717mgNH 4 + -N/gAGB/h) and denitrification rate (DNR) (5.0852±0.0891mgNO 3 - -N/gAGB/h), followed by R-20 and R-10. These results indicated AOR, DNR and AGB were affected by the filling ratio under the same operation mode. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gas-Liquid Two-Phase Flows Through Packed Bed Reactors in Microgravity

NASA Technical Reports Server (NTRS)

Motil, Brian J.; Balakotaiah, Vemuri

2001-01-01

The simultaneous flow of gas and liquid through a fixed bed of particles occurs in many unit operations of interest to the designers of space-based as well as terrestrial equipment. Examples include separation columns, gas-liquid reactors, humidification, drying, extraction, and leaching. These operations are critical to a wide variety of industries such as petroleum, pharmaceutical, mining, biological, and chemical. NASA recognizes that similar operations will need to be performed in space and on planetary bodies such as Mars if we are to achieve our goals of human exploration and the development of space. The goal of this research is to understand how to apply our current understanding of two-phase fluid flow through fixed-bed reactors to zero- or partial-gravity environments. Previous experiments by NASA have shown that reactors designed to work on Earth do not necessarily function in a similar manner in space. Two experiments, the Water Processor Assembly and the Volatile Removal Assembly have encountered difficulties in predicting and controlling the distribution of the phases (a crucial element in the operation of this type of reactor) as well as the overall pressure drop.

Modeling fixed and fluidized reactors for cassava starch Saccharification with immobilized enzyme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanin, G.M.; De Moraes, F.F.

1997-12-31

Cassava starch saccharification in fixed-and fluidized-bed reactors using immobilized enzyme was modeled in a previous paper using a simple model in which all dextrins were grouped in a single substrate. In that case, although good fit of the model to experimental data was obtained, physical inconsistency appeared as negative kinetic constants. In this work, a multisubstrate model, developed earlier for saccharification with free enzyme, is adapted for immobilized enzyme. This latter model takes into account the formation of intermediate substrates, which are dextrins competing for the catalytic site of the enzyme, reversibility of some reactions, inhibition by substrate and product,more » and the formation of isomaltose. Kinetic parameters to be used with this model were obtained from initial velocity saccharification tests using the immobilized enzyme and different liquefied starch concentrations. The new model was found to be valid for modeling both fixed- and fluidized-bed reactors. It did not present inconsistencies as the earlier one had and has shown that apparent glucose inhibition is about seven times higher in the fixed-bed than in fluidized-bed reactor. 13 refs., 5 figs., 1 tab.« less

Modeling of circulating fluised beds for post-combustion carbon capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, A.; Shadle, L.; Miller, D.

2011-01-01

A compartment based model for a circulating fluidized bed reactor has been developed based on experimental observations of riser hydrodynamics. The model uses a cluster based approach to describe the two-phase behavior of circulating fluidized beds. Fundamental mass balance equations have been derived to describe the movement of both gas and solids though the system. Additional work is being performed to develop the correlations required to describe the hydrodynamics of the system. Initial testing of the model with experimental data shows promising results and highlights the importance of including end effects within the model.

Development of a Reactor Model for Chemical Conversion of Lunar Regolith

NASA Technical Reports Server (NTRS)

Hegde, U.; Balasubramaniam, R.; Gokoglu, S.

2009-01-01

Lunar regolith will be used for a variety of purposes such as oxygen and propellant production and manufacture of various materials. The design and development of chemical conversion reactors for processing lunar regolith will require an understanding of the coupling among the chemical, mass and energy transport processes occurring at the length and time scales of the overall reactor with those occurring at the corresponding scales of the regolith particles. To this end, a coupled transport model is developed using, as an example, the reduction of ilmenite-containing regolith by a continuous flow of hydrogen in a flow-through reactor. The ilmenite conversion occurs on the surface and within the regolith particles. As the ilmenite reduction proceeds, the hydrogen in the reactor is consumed, and this, in turn, affects the conversion rate of the ilmenite in the particles. Several important quantities are identified as a result of the analysis. Reactor scale parameters include the void fraction (i.e., the fraction of the reactor volume not occupied by the regolith particles) and the residence time of hydrogen in the reactor. Particle scale quantities include the time for hydrogen to diffuse into the pores of the regolith particles and the chemical reaction time. The paper investigates the relationships between these quantities and their impact on the regolith conversion. Application of the model to various chemical reactor types, such as fluidized-bed, packed-bed, and rotary-bed configurations, are discussed.

Development of a Reactor Model for Chemical Conversion of Lunar Regolith

NASA Technical Reports Server (NTRS)

Hedge, uday; Balasubramaniam, R.; Gokoglu, S.

2007-01-01

Lunar regolith will be used for a variety of purposes such as oxygen and propellant production and manufacture of various materials. The design and development of chemical conversion reactors for processing lunar regolith will require an understanding of the coupling among the chemical, mass and energy transport processes occurring at the length and time scales of the overall reactor with those occurring at the corresponding scales of the regolith particles. To this end, a coupled transport model is developed using, as an example, the reduction of ilmenite-containing regolith by a continuous flow of hydrogen in a flow-through reactor. The ilmenite conversion occurs on the surface and within the regolith particles. As the ilmenite reduction proceeds, the hydrogen in the reactor is consumed, and this, in turn, affects the conversion rate of the ilmenite in the particles. Several important quantities are identified as a result of the analysis. Reactor scale parameters include the void fraction (i.e., the fraction of the reactor volume not occupied by the regolith particles) and the residence time of hydrogen in the reactor. Particle scale quantities include the time for hydrogen to diffuse into the pores of the regolith particles and the chemical reaction time. The paper investigates the relationships between these quantities and their impact on the regolith conversion. Application of the model to various chemical reactor types, such as fluidized-bed, packed-bed, and rotary-bed configurations, are discussed.

Design of Complex Systems to Achieve Passive Safety: Natural Circulation Cooling of Liquid Salt Pebble Bed Reactors

NASA Astrophysics Data System (ADS)

Scarlat, Raluca Olga

This dissertation treats system design, modeling of transient system response, and characterization of individual phenomena and demonstrates a framework for integration of these three activities early in the design process of a complex engineered system. A system analysis framework for prioritization of experiments, modeling, and development of detailed design is proposed. Two fundamental topics in thermal-hydraulics are discussed, which illustrate the integration of modeling and experimentation with nuclear reactor design and safety analysis: thermal-hydraulic modeling of heat generating pebble bed cores, and scaled experiments for natural circulation heat removal with Boussinesq liquids. The case studies used in this dissertation are derived from the design and safety analysis of a pebble bed fluoride salt cooled high temperature nuclear reactor (PB-FHR), currently under development in the United States at the university and national laboratories level. In the context of the phenomena identification and ranking table (PIRT) methodology, new tools and approaches are proposed and demonstrated here, which are specifically relevant to technology in the early stages of development, and to analysis of passive safety features. A system decomposition approach is proposed. Definition of system functional requirements complements identification and compilation of the current knowledge base for the behavior of the system. Two new graphical tools are developed for ranking of phenomena importance: a phenomena ranking map, and a phenomena identification and ranking matrix (PIRM). The functional requirements established through this methodology were used for the design and optimization of the reactor core, and for the transient analysis and design of the passive natural circulation driven decay heat removal system for the PB-FHR. A numerical modeling approach for heat-generating porous media, with multi-dimensional fluid flow is presented. The application of this modeling approach to the PB-FHR annular pebble bed core cooled by fluoride salt mixtures generated a model that is called Pod. Pod. was used to show the resilience of the PB-FHR core to generation of hot spots or cold spots, due to the effect of buoyancy on the flow and temperature distribution in the packed bed. Pod. was used to investigate the PB-FHR response to ATWS transients. Based on the functional requirements for the core, Pod. was used to generate an optimized design of the flow distribution in the core. An analysis of natural circulation loops cooled by single-phase Boussinesq fluids is presented here, in the context of reactor design that relies on natural circulation decay heat removal, and design of scaled experiments. The scaling arguments are established for a transient natural circulation loop, for loops that have long fluid residence time, and negligible contribution of fluid inertia to the momentum equation. The design of integral effects tests for the loss of forced circulation (LOFC) for PB-FHR is discussed. The special case of natural circulation decay heat removal from a pebble bed reactor was analyzed. A way to define the Reynolds number in a multi-dimensional pebble bed was identified. The scaling methodology for replicating pebble bed friction losses using an electrically resistance heated annular pipe and a needle valve was developed. The thermophysical properties of liquid fluoride salts lead to design of systems with low flow velocities, and hence long fluid residence times. A comparison among liquid coolants for the performance of steady state natural circulation heat removal from a pebble bed was performed. Transient natural circulation experimental data with simulant fluids for fluoride salts is given here. The low flow velocity and the relatively high viscosity of the fluoride salts lead to low Reynolds number flows, and a low Reynolds number in conjunction with a sufficiently high coefficient of thermal expansion makes the system susceptible to local buoyancy effects Experiments indicate that slow exchange of stagnant fluid in static legs can play a significant role in the transient response of natural circulation loops. The effect of non-linear temperature profiles on the hot or cold legs or other segments of the flow loop, which may develop during transient scenarios, should be considered when modeling the performance of natural circulation loops. The data provided here can be used for validation of the application of thermal-hydraulic systems codes to the modeling of heat removal by natural circulation with liquid fluoride salts and its simulant fluids.

Development and applications of methodologies for the neutronic design of the Pebble Bed Advanced High Temperature Reactor (PB-AHTR)

NASA Astrophysics Data System (ADS)

Fratoni, Massimiliano

This study investigated the neutronic characteristics of the Pebble Bed Advanced High Temperature Reactor (PB-AHTR), a novel nuclear reactor concept that combines liquid salt (7LiF-BeF2---flibe) cooling and TRISO coated-particle fuel technology. The use of flibe enables operation at high power density and atmospheric pressure and improves passive decay-heat removal capabilities, but flibe, unlike conventional helium coolant, is not transparent to neutrons. The flibe occupies 40% of the PB-AHTR core volume and absorbs ˜8% of the neutrons, but also acts as an effective neutron moderator. Two novel methodologies were developed for calculating the time dependent and equilibrium core composition: (1) a simplified single pebble model that is relatively fast; (2) a full 3D core model that is accurate and flexible but computationally intensive. A parametric analysis was performed spanning a wide range of fuel kernel diameters and graphite-to-heavy metal atom ratios to determine the attainable burnup and reactivity coefficients. Using 10% enriched uranium ˜130 GWd/tHM burnup was found to be attainable, when the graphite-to-heavy metal atom ratio (C/HM) is in the range of 300 to 400. At this or smaller C/HM ratio all reactivity coefficients examined---coolant temperature, coolant small and full void, fuel temperature, and moderator temperature, were found to be negative. The PB-AHTR performance was compared to that of alternative options for HTRs, including the helium-cooled pebble-bed reactor and prismatic fuel reactors, both gas-cooled and flibe-cooled. The attainable burnup of all designs was found to be similar. The PB-AHTR generates at least 30% more energy per pebble than the He-cooled pebble-bed reactor. Compared to LWRs the PB-AHTR requires 30% less natural uranium and 20% less separative work per unit of electricity generated. For deep burn TRU fuel made from recycled LWR spent fuel, it was found that in a single pass through the core ˜66% of the TRU can be transmuted; this burnup is slightly superior to that attainable in helium-cooled reactors. A preliminary analysis of the modular variant for the PB-AHTR investigated the triple heterogeneity of this design and determined its performance characteristics.

Nuclear reactor cooling system decontamination reagent regeneration. [PWR; BWR

DOEpatents

Anstine, L.D.; James, D.B.; Melaika, E.A.; Peterson, J.P. Jr.

1980-06-06

An improved method for decontaminating the coolant system of water-cooled nuclear power reactors and for regenerating the decontamination solution is described. A small amount of one or more weak-acid organic complexing agents is added to the reactor coolant, and the pH is adjusted to form a decontamination solution which is circulated throughout the coolant system to dissolve metal oxides from the interior surfaces and complex the resulting metal ions and radionuclide ions. The coolant containing the complexed metal ions and radionuclide ions is passed through a strong-base anion exchange resin bed which has been presaturated with a solution containing the complexing agents in the same ratio and having the same pH as the decontamination solution. As the decontamination solution passes through the resin bed, metal-complexed anions are exchanged for the metal-ion-free anions on the bed, while metal-ion-free anions in the solution pass through the bed, thus removing the metal ions and regenerating the decontamination solution.

Nuclear reactor cooling system decontamination reagent regeneration

DOEpatents

Anstine, Larry D.; James, Dean B.; Melaika, Edward A.; Peterson, Jr., John P.

1985-01-01

An improved method for decontaminating the coolant system of water-cooled nuclear power reactors and for regenerating the decontamination solution. A small amount of one or more weak-acid organic complexing agents is added to the reactor coolant, and the pH is adjusted to form a decontamination solution which is circulated throughout the coolant system to dissolve metal oxides from the interior surfaces and complex the resulting metal ions and radionuclide ions. The coolant containing the complexed metal ions and radionuclide ions is passed through a strong-base anion exchange resin bed which has been presaturated with a solution containing the complexing agents in the same ratio and having the same pH as the decontamination solution. As the decontamination solution passes through the resin bed, metal-complexed anions are exchanged for the metal-ion-free anions on the bed, while metal-ion-free anions in the solution pass through the bed, thus removing the metal ions and regenerating the decontamination solution.

Design and Analysis of Embedded I&C for a Fully Submerged Magnetically Suspended Impeller Pump

DOE PAGES

Melin, Alexander M.; Kisner, Roger A.

2018-04-03

Improving nuclear reactor power system designs and fuel-processing technologies for safer and more efficient operation requires the development of new component designs. In particular, many of the advanced reactor designs such as the molten salt reactors and high-temperature gas-cooled reactors have operating environments beyond the capability of most currently available commercial components. To address this gap, new cross-cutting technologies need to be developed that will enable design, fabrication, and reliable operation of new classes of reactor components. The Advanced Sensor Initiative of the Nuclear Energy Enabling Technologies initiative is investigating advanced sensor and control designs that are capable of operatingmore » in these extreme environments. Under this initiative, Oak Ridge National Laboratory (ORNL) has been developing embedded instrumentation and control (I&C) for extreme environments. To develop, test, and validate these new sensing and control techniques, ORNL is building a pump test bed that utilizes submerged magnetic bearings to levitate the shaft. The eventual goal is to apply these techniques to a high-temperature (700°C) canned rotor pump that utilizes active magnetic bearings to eliminate the need for mechanical bearings and seals. The technologies will benefit the Next Generation Power Plant, Advanced Reactor Concepts, and Small Modular Reactor programs. In this paper, we will detail the design and analysis of the embedded I&C test bed with submerged magnetic bearings, focusing on the interplay between the different major systems. Then we will analyze the forces on the shaft and their role in the magnetic bearing design. Next, we will develop the radial and thrust bearing geometries needed to meet the operational requirements of the test bed. In conclusion, we will present some initial system identification results to validate the theoretical models of the test bed dynamics.« less

Design and Analysis of Embedded I&C for a Fully Submerged Magnetically Suspended Impeller Pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melin, Alexander M.; Kisner, Roger A.

Improving nuclear reactor power system designs and fuel-processing technologies for safer and more efficient operation requires the development of new component designs. In particular, many of the advanced reactor designs such as the molten salt reactors and high-temperature gas-cooled reactors have operating environments beyond the capability of most currently available commercial components. To address this gap, new cross-cutting technologies need to be developed that will enable design, fabrication, and reliable operation of new classes of reactor components. The Advanced Sensor Initiative of the Nuclear Energy Enabling Technologies initiative is investigating advanced sensor and control designs that are capable of operatingmore » in these extreme environments. Under this initiative, Oak Ridge National Laboratory (ORNL) has been developing embedded instrumentation and control (I&C) for extreme environments. To develop, test, and validate these new sensing and control techniques, ORNL is building a pump test bed that utilizes submerged magnetic bearings to levitate the shaft. The eventual goal is to apply these techniques to a high-temperature (700°C) canned rotor pump that utilizes active magnetic bearings to eliminate the need for mechanical bearings and seals. The technologies will benefit the Next Generation Power Plant, Advanced Reactor Concepts, and Small Modular Reactor programs. In this paper, we will detail the design and analysis of the embedded I&C test bed with submerged magnetic bearings, focusing on the interplay between the different major systems. Then we will analyze the forces on the shaft and their role in the magnetic bearing design. Next, we will develop the radial and thrust bearing geometries needed to meet the operational requirements of the test bed. In conclusion, we will present some initial system identification results to validate the theoretical models of the test bed dynamics.« less

Controlled biomass formation and kinetics of toluene degradation in a bioscrubber and in a reactor with a periodically moved trickle-bed.

PubMed

Wübker, S M; Laurenzis, A; Werner, U; Friedrich, C

1997-08-20

The kinetics of degradation of toluene from a model waste gas and of biomass formation were examined in a bioscrubber operated under different nutrient limitations with a mixed culture. The applicability of the kinetics of continuous cultivation of the mixed culture was examined for a special trickle-bed reactor with a periodically moved filter bed. The efficiency of toluene elimination of the bioscrubber was 50 to 57% and depended on the toluene mass transfer as evident from a constant productivity of 0.026 g dry cell weight/L . h over the dilution rate. Under potassium limitation the biomass productivity was reduced by 60% to 0.011 g dry cell weight/L . h at a dilution rate of 0.013/h. Conversely, at low dilution rates the specific toluene degradation rates increased. Excess biomass in a trickle-bed reactor causes reduction of interfacial area and mass transfer, and increase in pressure drop. To avoid these disadvantages, the trickle-bed was moved periodically and biomass was removed with outflowing medium. The concentration of steady state biomass fixed on polyamide beads decreased hyperbolically with the dilution rate. Also, the efficiency of toluene degradation decreased from 72 to 56% with increasing dilution rate while the productivity increased. Potassium limitation generally caused a reduction in biomass, productivity, and yield while the specific degradation increased with dilution rate. This allowed the application of the principles of the chemostat to the trickle-bed reactor described here, for toluene degradation from waste gases. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 686-692, 1997.

Rotating packed bed reactor for enzymatic synthesis of biodiesel.

PubMed

Xu, Juntao; Liu, Changsheng; Wang, Meng; Shao, Lei; Deng, Li; Nie, Kaili; Wang, Fang

2017-01-01

The aim of the present work was to study the applicability of rotating packed bed (RPB) for biodiesel through the biocatalytic method. In this research, the RPB facilitated a more homogeneous mixture of substrates due to its higher mass transfer efficiency and better micromixing environment. This was superior to the traditional continuous stirred tank reactor (CSTR) system. Candida sp. 99-125 lipase was used without any organic solvent or additive, and demonstrated a significant catalyst efficiency. The key factors, such as the high gravity factor (β), pattern of the catalyst and methanol-FFA molar ratio etc. were investigated. Under the optimal conditions, the hydrolysis yield of fatty acids was 97.0% after 24h and the esterification yield of biodiesel was 96.0% 6h later. The esterifying yield didn't have an obvious decline in the fifth batch. Consequently, the RPB is an attractive and effective reactor for enzymatic synthesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

HTR-PROTEUS pebble bed experimental program cores 9 & 10: columnar hexagonal point-on-point packing with a 1:1 moderator-to-fuel pebble ratio

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bess, John D.

2014-03-01

PROTEUS is a zero-power research reactor based on a cylindrical graphite annulus with a central cylindrical cavity. The graphite annulus remains basically the same for all experimental programs, but the contents of the central cavity are changed according to the type of reactor being investigated. Through most of its service history, PROTEUS has represented light-water reactors, but from 1992 to 1996 PROTEUS was configured as a pebble-bed reactor (PBR) critical facility and designated as HTR-PROTEUS. The nomenclature was used to indicate that this series consisted of High Temperature Reactor experiments performed in the PROTEUS assembly. During this period, seventeen criticalmore » configurations were assembled and various reactor physics experiments were conducted. These experiments included measurements of criticality, differential and integral control rod and safety rod worths, kinetics, reaction rates, water ingress effects, and small sample reactivity effects (Ref. 3). HTR-PROTEUS was constructed, and the experimental program was conducted, for the purpose of providing experimental benchmark data for assessment of reactor physics computer codes. Considerable effort was devoted to benchmark calculations as a part of the HTR-PROTEUS program. References 1 and 2 provide detailed data for use in constructing models for codes to be assessed. Reference 3 is a comprehensive summary of the HTR-PROTEUS experiments and the associated benchmark program. This document draws freely from these references. Only Cores 9 and 10 are evaluated in this benchmark report due to similarities in their construction. The other core configurations of the HTR-PROTEUS program are evaluated in their respective reports as outlined in Section 1.0. Cores 9 and 10 were evaluated and determined to be acceptable benchmark experiments.« less

HTR-PROTEUS PEBBLE BED EXPERIMENTAL PROGRAM CORES 5, 6, 7, & 8: COLUMNAR HEXAGONAL POINT-ON-POINT PACKING WITH A 1:2 MODERATOR-TO-FUEL PEBBLE RATIO

DOE Office of Scientific and Technical Information (OSTI.GOV)

John D. Bess

2013-03-01

PROTEUS is a zero-power research reactor based on a cylindrical graphite annulus with a central cylindrical cavity. The graphite annulus remains basically the same for all experimental programs, but the contents of the central cavity are changed according to the type of reactor being investigated. Through most of its service history, PROTEUS has represented light-water reactors, but from 1992 to 1996 PROTEUS was configured as a pebble-bed reactor (PBR) critical facility and designated as HTR-PROTEUS. The nomenclature was used to indicate that this series consisted of High Temperature Reactor experiments performed in the PROTEUS assembly. During this period, seventeen criticalmore » configurations were assembled and various reactor physics experiments were conducted. These experiments included measurements of criticality, differential and integral control rod and safety rod worths, kinetics, reaction rates, water ingress effects, and small sample reactivity effects (Ref. 3). HTR-PROTEUS was constructed, and the experimental program was conducted, for the purpose of providing experimental benchmark data for assessment of reactor physics computer codes. Considerable effort was devoted to benchmark calculations as a part of the HTR-PROTEUS program. References 1 and 2 provide detailed data for use in constructing models for codes to be assessed. Reference 3 is a comprehensive summary of the HTR-PROTEUS experiments and the associated benchmark program. This document draws freely from these references. Only Cores 9 and 10 are evaluated in this benchmark report due to similarities in their construction. The other core configurations of the HTR-PROTEUS program are evaluated in their respective reports as outlined in Section 1.0. Cores 9 and 10 were evaluated and determined to be acceptable benchmark experiments.« less

HTR-PROTEUS PEBBLE BED EXPERIMENTAL PROGRAM CORES 9 & 10: COLUMNAR HEXAGONAL POINT-ON-POINT PACKING WITH A 1:1 MODERATOR-TO-FUEL PEBBLE RATIO

DOE Office of Scientific and Technical Information (OSTI.GOV)

John D. Bess

2013-03-01

PROTEUS is a zero-power research reactor based on a cylindrical graphite annulus with a central cylindrical cavity. The graphite annulus remains basically the same for all experimental programs, but the contents of the central cavity are changed according to the type of reactor being investigated. Through most of its service history, PROTEUS has represented light-water reactors, but from 1992 to 1996 PROTEUS was configured as a pebble-bed reactor (PBR) critical facility and designated as HTR-PROTEUS. The nomenclature was used to indicate that this series consisted of High Temperature Reactor experiments performed in the PROTEUS assembly. During this period, seventeen criticalmore » configurations were assembled and various reactor physics experiments were conducted. These experiments included measurements of criticality, differential and integral control rod and safety rod worths, kinetics, reaction rates, water ingress effects, and small sample reactivity effects (Ref. 3). HTR-PROTEUS was constructed, and the experimental program was conducted, for the purpose of providing experimental benchmark data for assessment of reactor physics computer codes. Considerable effort was devoted to benchmark calculations as a part of the HTR-PROTEUS program. References 1 and 2 provide detailed data for use in constructing models for codes to be assessed. Reference 3 is a comprehensive summary of the HTR-PROTEUS experiments and the associated benchmark program. This document draws freely from these references. Only Cores 9 and 10 are evaluated in this benchmark report due to similarities in their construction. The other core configurations of the HTR-PROTEUS program are evaluated in their respective reports as outlined in Section 1.0. Cores 9 and 10 were evaluated and determined to be acceptable benchmark experiments.« less

Treatment of oilfield wastewater in moving bed biofilm reactors using a novel suspended ceramic biocarrier.

PubMed

Dong, Zhiyong; Lu, Mang; Huang, Wenhui; Xu, Xiaochun

2011-11-30

In this study, a novel suspended ceramic carrier was prepared, which has high strength, optimum density (close to water), and high porosity. Two different carriers, unmodified and sepiolite-modified suspended ceramic carriers were used to feed two moving bed biofilm reactors (MBBRs) with a filling fraction of 50% to treat oilfield produced water. The hydraulic retention time (HRT) was varied from 36 to 10h. The results, during a monitoring period of 190 days, showed that removal efficiency of chemical oxygen demand was the highest in reactor 3 filled with the sepiolite-modified carriers, followed by reactor 2 filled with the unmodified carriers, with the lowest in reactor 1 (activated sludge reactor), at an HRT of 10h. Similar trends were found in the removal efficiencies of ammonia nitrogen and polycyclic aromatic hydrocarbons. Reactor 3 was more shock resistant than reactors 2 and 1. The results indicate that the suspended ceramic carrier is an excellent MBBR carrier. Copyright © 2011 Elsevier B.V. All rights reserved.

Effects of temperature, pressure, and carrier gas on the cracking of coal tar over a char-dolomite mixtures and calcined dolomite in a fixed-bed reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seshadri, K.; Shamsi, A.

1998-10-01

A distillation fraction of a coal-derived liquid (tar) was cracked over a char-dolomite mixture, calcined dolomite, and silicon carbide in a fixed-bed reactor. The char-dolomite mixture (FWC) was produced from Pittsburgh No. 8 coal and dolomite in a Foster Wheeler carbonizer. The experiments were conducted under nitrogen and simulated coal gas (SCG), which was a mixture of CO, CO{sub 2}, H{sub 2}S, CH{sub 4}, N{sub 2}, and steam, at 1 and 17 atm. The conversion over these materials under nitrogen was much higher at 17 atm than at 1 atm. At higher pressures, tar molecules were trapped in the poresmore » of the bed material and underwent secondary reactions, resulting in the formation of excess char. However, when nitrogen was replaced by SCG, the reactions that induce char formation were suppressed, thus increasing the yield of gaseous products. The analysis of the gaseous products and the spent bed materials for organic and inorganic carbons suggested that the product distribution can be altered by changing the carrier gas, temperature, and pressure.« less

Pebble Fuel Handling and Reactivity Control for Salt-Cooled High Temperature Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, Per; Greenspan, Ehud

2015-02-09

This report documents the work completed on the X-PREX facility under NEUP Project 11- 3172. This project seeks to demonstrate the viability of pebble fuel handling and reactivity control for fluoride salt-cooled high-temperature reactors (FHRs). The research results also improve the understanding of pebble motion in helium-cooled reactors, as well as the general, fundamental understanding of low-velocity granular flows. Successful use of pebble fuels in with salt coolants would bring major benefits for high-temperature reactor technology. Pebble fuels enable on-line refueling and operation with low excess reactivity, and thus simpler reactivity control and improved fuel utilization. If fixed fuel designsmore » are used, the power density of salt- cooled reactors is limited to 10 MW/m 3 to obtain adequate duration between refueling, but pebble fuels allow power densities in the range of 20 to 30 MW/m 3. This can be compared to the typical modular helium reactor power density of 5 MW/m3. Pebble fuels also permit radial zoning in annular cores and use of thorium or graphite pebble blankets to reduce neutron fluences to outer radial reflectors and increase total power production. Combined with high power conversion efficiency, compact low-pressure primary and containment systems, and unique safety characteristics including very large thermal margins (>500°C) to fuel damage during transients and accidents, salt-cooled pebble fuel cores offer the potential to meet the major goals of the Advanced Reactor Concepts Development program to provide electricity at lower cost than light water reactors with improved safety and system performance.This report presents the facility description, experimental results, and supporting simulation methods of the new X-Ray Pebble Recirculation Experiment (X-PREX), which is now operational and being used to collect data on the behavior of slow dense granular flows relevant to pebble bed reactor core designs. The X-PREX facility uses novel digital x-ray tomography methods to track both the translational and rotational motion of spherical pebbles, which provides unique experimental results that can be used to validate discrete element method (DEM) simulations of pebble motion. The validation effort supported by the X-PREX facility provides a means to build confidence in analysis of pebble bed configuration and residence time distributions that impact the neutronics, thermal hydraulics, and safety analysis of pebble bed reactor cores. Experimental and DEM simulation results are reported for silo drainage, a classical problem in the granular flow literature, at several hopper angles. These studies include conventional converging and novel diverging geometries that provide additional flexibility in the design of pebble bed reactor cores. Excellent agreement is found between the X-PREX experimental and DEM simulation results. This report also includes results for additional studies relevant to the design and analysis of pebble bed reactor cores including the study of forces on shut down blades inserted directly into a packed bed and pebble flow in a cylindrical hopper that is representative of a small test reactor.« less

Heat dissipating nuclear reactor

DOEpatents

Hunsbedt, A.; Lazarus, J.D.

1985-11-21

Disclosed is a nuclear reactor containment adapted to retain and cool core debris in the unlikely event of a core meltdown and subsequent breach in the reactor vessel. The reactor vessel is seated in a cavity which has a thick metal sidewall that is integral with a thick metal basemat at the bottom of the cavity. The basemat extends beyond the perimeter of the cavity sidewall. Underneath the basemat is a porous bed with water pipes and steam pipes running into it. Water is introduced into the bed and converted into steam which is vented to the atmosphere. A plurality of metal pilings in the form of H-beams extend from the metal base plate downwardly and outwardly into the earth.

Heat dissipating nuclear reactor

DOEpatents

Hunsbedt, Anstein; Lazarus, Jonathan D.

1987-01-01

Disclosed is a nuclear reactor containment adapted to retain and cool core debris in the unlikely event of a core meltdown and subsequent breach in the reactor vessel. The reactor vessel is seated in a cavity which has a thick metal sidewall that is integral with a thick metal basemat at the bottom of the cavity. The basemat extends beyond the perimeter of the cavity sidewall. Underneath the basemat is a porous bed with water pipes and steam pipes running into it. Water is introduced into the bed and converted into steam which is vented to the atmosphere. A plurality of metal pilings in the form of H-beams extends from the metal base plate downwardly and outwardly into the earth.

High-rate treatment of molasses wastewater by combination of an acidification reactor and a USSB reactor.

PubMed

Onodera, Takashi; Sase, Shinya; Choeisai, Pairaya; Yoochatchaval, Wilasinee; Sumino, Haruhiko; Yamaguchi, Takashi; Ebie, Yoshitaka; Xu, Kaiqin; Tomioka, Noriko; Syutsubo, Kazuaki

2011-01-01

A combination of an acidification reactor and an up-flow staged sludge bed (USSB) reactor was applied for treatment of molasses wastewater containing a large amount of organic compounds and sulfate. The USSB reactor had three gas-solid separators (GSS) along the height of the reactor. The combined system was continuously operated at mesophilic temperature over 400 days. In the acidification reactor, acid formation and sulfate reduction were effectively carried out. The sugars contained in the influent wastewater were mostly acidified into acetate, propionate, and n-butyrate. In addition, 10-30% of influent sulfur was removed from the acidification reactor by means of sulfate reduction followed by stripping of hydrogen sulfide. The USSB achieved a high organic loading rate (OLR) of 30 kgCOD m(-3) day(-1) with 82% COD removal. Vigorous biogas production was observed at a rate of 15 Nm(3) biogas m(-3) reactor day(-1). The produced biogas, including hydrogen sulfide, was removed from the wastewater mostly via the GSS. The GSS provided a moderate superficial biogas flux and low sulfide concentration in the sludge bed, resulting in the prevention of sludge washout and sulfide inhibition of methanogens. By advantages of this feature, the USSB may have been responsible for achieving sufficient retention (approximately 60 gVSS L(-1)) of the granular sludge with high methanogenic activity (0.88 gCOD gVSS(-1) day(-1) for acetate and as high as 2.6 gCOD gVSS(-1) day(-1) for H(2)/CO(2)). Analysis of the microbial community revealed that sugar-degrading acid-forming bacteria proliferated in the sludge of the USSB as well as the acidification reactor at high OLR conditions.

Effect of bacterial lipase on anaerobic co-digestion of slaughterhouse wastewater and grease in batch condition and continuous fixed-bed reactor.

PubMed

Affes, Maha; Aloui, Fathi; Hadrich, Fatma; Loukil, Slim; Sayadi, Sami

2017-10-10

This study aimed to investigate the effects of bacterial lipase on biogas production of anaerobic co-digestion of slaughterhouse wastewater (SHWW) and hydrolyzed grease (HG). A neutrophilic Staphylococcus xylosus strain exhibiting lipolytic activity was used to perform microbial hydrolysis pretreatment of poultry slaughterhouse lipid rich waste. Optimum proportion of hydrolyzed grease was evaluated by determining biochemical methane potential. A high biogas production was observed in batch containing a mixture of slaughterhouse composed of 75% SHWW and 25% hydrolyzed grease leading to a biogas yield of 0.6 L/g COD introduced. Fixed bed reactor (FBR) results confirmed that the proportion of 25% of hydrolyzed grease gives the optimum condition for the digester performance. Biogas production was significantly high until an organic loading rate (OLR) of 2 g COD/L. d. This study indicates that the use of biological pre-treatment and FBR for the co-digestion of SHWW and hydrolyzed grease is feasible and effective.

Fluorescence-based monitoring of tracer and substrate distribution in an UASB reactor.

PubMed

Lou, S J; Tartakovsky, B; Zeng, Y; Wu, P; Guiot, S R

2006-11-01

In this work, rhodamine-related fluorescence was measured on-line at four reactor heights in order to study hydrodynamics within an upflow anaerobic sludge bed reactor. A linear dependence of the dispersion coefficient (D) on the upflow velocity was observed, while the influence of the organic loading rate (OLR) was insignificant. Furthermore, the Bodenstein number of the reactor loaded with granulated sludge was found to be position-dependent with the largest values measured at the bottom of the sludge bed. This trend was not observed in the reactor without sludge. Chemical oxygen demand (COD) and volatile fatty acid (VFA) concentrations were measured at the same reactor heights as in rhodamine tests using conventional off-line analytical methods and on-line multiwavelength fluorometry. Significant spatial COD and VFA gradients were observed at organic loading rates above 6g COD l(R)(-1)d(-1) and linear upflow velocities below 0.8m h(-1).

Gas treatment in trickle-bed biofilters: biomass, how much is enough?

PubMed

Alonso, C; Suidan, M T; Sorial, G A; Smith, F L; Biswas, P; Smith, P J; Brenner, R C

1997-06-20

The objective of this article is to define and validate a mathematical model that desribes the physical and biological processes occurring in a trickle-bed air biofilter for waste gas treatment. This model considers a two-phase system, quasi-steady-state processes, uniform bacterial population, and one limiting substrate. The variation of the specific surface area with bacterial growth is included in the model, and its effect on the biofilter performance is analyzed. This analysis leads to the conclusion that excessive accumulation of biomass in the reactor has a negative effect on contaminant removal efficiency. To solve this problem, excess biomass is removed via full media fluidization and backwashing of the biofilter. The backwashing technique is also incorporated in the model as a process variable. Experimental data from the biodegradation of toluene in a pilot system with four packed-bed reactors are used to validate the model. Once the model is calibrated with the estimation of the unknown parameters of the system, it is used to simulate the biofilter performance for different operating conditions. Model predictions are found to be in agreement with experimental data. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 583-594, 1997.

Effect of filter media size, mass flow rate and filtration stage number in a moving-bed granular filter on the yield and properties of bio-oil from fast pyrolysis of biomass.

PubMed

Paenpong, Chaturong; Inthidech, Sudsakorn; Pattiya, Adisak

2013-07-01

Fast pyrolysis of cassava rhizome was performed in a bench-scale fluidised-bed reactor unit incorporated with a cross-flow moving-bed granular filter. The objective of this research was to examine several process parameters including the granular size (425-1160 μm) and mass flow rate (0-12 g/min) as well as the number of the filtration stages (1-2 stages) on yields and properties of bio-oil. The results showed that the bio-oil yield decreased from 57.7 wt.% to 42.0-49.2 wt.% when increasing the filter media size, the mass flow rate and the filtration stage number. The effect of the process parameters on various properties of bio-oil is thoroughly discussed. In general, the bio-oil quality in terms of the solids content, ash content, initial viscosity, viscosity change and ageing rate could be enhanced by the hot vapour granular filtration. Therefore, bio-oil of high stability could be produced by the pyrolysis reactor configuration designed in this work. Copyright © 2013 Elsevier Ltd. All rights reserved.

Monitoring of itaconic acid hydrogenation in a trickle bed reactor using fiber-optic coupled near-infrared spectroscopy.

PubMed

Wood, Joseph; Turner, Paul H

2003-03-01

Near-infrared (NIR) spectroscopy has been applied to determine the conversion of itaconic acid in the effluent stream of a trickle bed reactor. Hydrogenation of itaconic to methyl succinic acid was carried out, with the trickle bed operating in recycle mode. For the first time, NIR spectra of itaconic and methyl succinic acids in aqueous solution, and aqueous mixtures withdrawn from the reactor over a range of reaction times, have been recorded using a fiberoptic sampling probe. The infrared spectra displayed a clear isolated absorption band at a wavenumber of 6186 cm(-1) (wavelength 1.617 microm) resulting from the =C-H bonds of itaconic acid, which was found to decrease in intensity with increasing reaction time. The feature could be more clearly observed from plots of the first derivatives of the spectra. A partial least-squares (PLS) model was developed from the spectra of 13 reference samples and was used successfully to calculate the concentration of the two acids in the reactor effluent solution. Itaconic acid conversions of 23-29% were calculated after 360 min of reaction time. The potential of FT-NIR with fiber-optic sampling for remote monitoring of three-phase catalytic reactors and validation of catalytic reactor models is highlighted in the paper.

Apple juice clarification by immobilized pectolytic enzymes in packed or fluidized bed reactors.

PubMed

Diano, Nadia; Grimaldi, Tiziana; Bianco, Mariangela; Rossi, Sergio; Gabrovska, Katya; Yordanova, Galya; Godjevargova, Tzonka; Grano, Valentina; Nicolucci, Carla; Mita, Luigi; Bencivenga, Umberto; Canciglia, Paolo; Mita, Damiano G

2008-12-10

The catalytic behavior of a mixture of pectic enzymes, covalently immobilized on different supports (glass microspheres, nylon 6/6 pellets, and PAN beads), was analyzed with a pectin aqueous solution that simulates apple juice. The following parameters were investigated: the rate constant at which pectin hydrolysis is conducted, the time (tau(50)) in which the reduction of 50% of the initial viscosity is reached, and the time (tau(comp,dep)) required to obtain complete depectinization. The best catalytic system was proven to be PAN beads, and their pH and temperature behavior were determined. The yields of two bed reactors, packed or fluidized, using the catalytic PAN beads, were compared to the circulation flow rate of real apple juice. The experimental conditions were as follows: pH 4.0, T = 50 degrees C, and beads volume = 20 cm(3). The initial pectin concentration was the one that was present in our apple juice sample. No differences were observed at low circulation rates, while at higher recirculation rates, the time required to obtain complete pectin hydrolysis into the fluidized reactor was found to be 0.25 times smaller than in the packed bed reactor: 131 min for the packed reactors and 41 min for the fluidized reactors.

Electrowinning apparatus and process

DOEpatents

Buschmann, Wayne E [Boulder, CO

2012-06-19

Apparatus and processes are disclosed for electrowinning metal from a fluid stream. A representative apparatus comprises at least one spouted bed reactor wherein each said reactor includes an anolyte chamber comprising an anode and configured for containing an anolyte, a catholyte chamber comprising a current collector and configured for containing a particulate cathode bed and a flowing stream of an electrically conductive metal-containing fluid, and a membrane separating said anolyte chamber and said catholyte chamber, an inlet for an electrically conductive metal-containing fluid stream; and a particle bed churning device configured for spouting particle bed particles in the catholyte chamber independently of the flow of said metal-containing fluid stream. In operation, reduced heavy metals or their oxides are recovered from the cathode particles.

Hydroliquefaction of coal

DOEpatents

Sze, Morgan C.; Schindler, Harvey D.

1982-01-01

Coal is catalytically hydroliquefied by passing coal dispersed in a liquefaction solvent and hydrogen upwardly through a plurality of parallel expanded catalyst beds, in a single reactor, in separate streams, each having a cross-sectional flow area of no greater than 255 inches square, with each of the streams through each of the catalyst beds having a length and a liquid and gas superficial velocity to maintain an expanded catalyst bed and provide a Peclet Number of at least 3. If recycle is employed, the ratio of recycle to total feed (coal and liquefaction solvent) is no greater than 2:1, based on volume. Such conditions provide for improved selectivity to liquid product to thereby reduce hydrogen consumption. The plurality of beds are formed by partitions in the reactor.

Bio-oil production from palm fronds by fast pyrolysis process in fluidized bed reactor

NASA Astrophysics Data System (ADS)

Rinaldi, Nino; Simanungkalit, Sabar P.; Kiky Corneliasari, S.

2017-01-01

Fast pyrolysis process of palm fronds has been conducted in the fluidized bed reactor to yield bio-oil product (pyrolysis oil). The process employed sea sand as the heat transfer medium. The objective of this study is to design of the fluidized bed rector, to conduct fast pyrolysis process to product bio-oil from palm fronds, and to characterize the feed and bio-oil product. The fast pyrolysis process was conducted continuously with the feeding rate around 500 g/hr. It was found that the biomass conversion is about 35.5% to yield bio-oil, however this conversion is still minor. It is suggested due to the heating system inside the reactor was not enough to decompose the palm fronds as a feedstock. Moreover, the acids compounds ware mostly observed on the bio-oil product.

The extraction of bitumen from western oil sands: Volume 2. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oblad, A.G.; Dahlstrom, D.A.; Deo, M.D.

1997-11-26

The program is composed of 20 projects, of which 17 are laboratory bench or laboratory pilot scale processes or computer process simulations that are performed in existing facilities on the University of Utah campus in north-east Salt Lake City. These tasks are: (1) coupled fluidized-bed bitumen recovery and coked sand combustion; (2) water-based recovery of bitumen; (3) oil sand pyrolysis in a continuous rotary kiln reactor; (4) oil sand pyrolysis in a large diameter fluidized bed reactor; (5) oil sand pyrolysis in a small diameter fluidized bed reactor; (6) combustion of spent sand in a transport reactor; (7) recovery andmore » upgrading of oil sand bitumen using solvent extraction methods; (8) fixed-bed hydrotreating of Uinta Basin bitumens and bitumen-derived hydrocarbon liquids; (9) ebullieted bed hydrotreating of bitumen and bitumen derived liquids; (10) bitumen upgrading by hydropyrolysis; (11) evaluation of Utah`s major oil sand deposits for the production of asphalt, high-energy jet fuels and other specialty products; (12) characterization of the bitumens and reservoir rocks from the Uinta Basin oil sand deposits; (13) bitumen upgrading pilot plant recommendations; (14) liquid-solid separation and fine tailings thickening; (15) in-situ production of heavy oil from Uinta Basin oil sand deposits; (16) oil sand research and development group analytical facility; and (17) process economics. This volume contains reports on nine of these projects, references, and a bibliography. 351 refs., 192 figs., 65 tabs.« less

Apparatus for high flux photocatalytic pollution control using a rotating fluidized bed reactor

DOEpatents

Tabatabaie-Raissi, Ali; Muradov, Nazim Z.; Martin, Eric

2003-06-24

An apparatus based on optimizing photoprocess energetics by decoupling of the process energy efficiency from the DRE for target contaminants. The technique is applicable to both low- and high-flux photoreactor design and scale-up. An apparatus for high-flux photocatalytic pollution control is based on the implementation of multifunctional metal oxide aerogels and other media in conjunction with a novel rotating fluidized particle bed reactor.

Industrial wastewater treatment in a new gas-induced ozone reactor.

PubMed

Lin, Sheng H; Wang, Ching H

2003-03-17

The present work was to investigate industrial wastewater treatment by ozonation in a new gas-induced reactor in conjunction with chemical coagulation pretreatment. The reactor was specifically designed in a fashion that gas induction was created on the liquid surface by the high-speed action of an impeller turbine inside a draft tube to maximize the ozone gas utilization. A new design feature of the present reactor system was a fixed granular activated carbon (GAC) bed packed in a circular compartment between the reactor wall and the shaft tube. The fixed GAC bed provided additional adsorption and catalytic degradation of organic pollutants. Combination of the fixed GAC bed and ozonation results in enhanced oxidation of organic pollutants. In addition to enhanced pollutant oxidation, ozonation was found to provide in situ GAC regeneration that was considered crucial in the present reaction system. Kinetic investigations were also made using a proposed complex kinetic model to elucidate the possible oxidation reaction mechanisms of the present gas-induced ozonation system. As a complementary measure, chemical coagulation pretreatment was found able to achieve up to 50% COD and 85% ADMI removal. Experimental tests were conducted to identify its optimum operating conditions. Copyright 2003 Elsevier Science B.V.

Efficient removal of antibiotics in a fluidized bed reactor by facile fabricated magnetic powdered activated carbon.

PubMed

Ma, Jianqing; Yang, Qunfeng; Xu, Dongmei; Zeng, Xiaomei; Wen, Yuezhong; Liu, Weiping

2017-02-01

Powdered activated carbons (PACs) with micrometer size are showing great potential for enabling and improving technologies in water treatment. The critical problem in achieving practical application of PAC involves simple, effective fabrication of magnetic PAC and the design of a feasible reactor that can remove pollutants and recover the adsorbent efficiently. Herein, we show that such materials can be fabricated by the combination of PAC and magnetic Fe 3 O 4 with chitosan-Fe hydrogel through a simple co-precipitation method. According to the characterization results, CS-Fe/Fe 3 O 4 /PAC with different micrometers in size exhibited excellent magnetic properties. The adsorption of tetracycline was fast and efficient, and 99.9% removal was achieved in 30 min. It also possesses good usability and stability to co-existing ions, organics, and different pH values due to its dispersive interaction nature. Finally, the prepared CS-Fe/Fe 3 O 4 /PAC also performed well in the fluidized bed reactor with electromagnetic separation function. It could be easily separated by applying a magnetic field and was effectively in situ regenerated, indicating a potential of practical application for the removal of pollutants from water.

Biomethanation of Harmful Macroalgal Biomass in Leach-Bed Reactor Coupled to Anaerobic Filter: Effect of Water Regime and Filter Media

PubMed Central

Jung, Heejung; Kim, Jaai; Lee, Changsoo

2018-01-01

Ulva is a marine macroalgal genus which causes serious green tides in coastal areas worldwide. This study investigated anaerobic digestion as a way to manage Ulva waste in a leach-bed reactor coupled to an anaerobic filter (LBR-AF). Two LBR-AF systems with different filter media, blast furnace slag grains for R1, and polyvinyl chloride rings for R2, were run at increasing water replacement rates (WRRs). Both achieved efficient volatile solids reduction (68.4–87.1%) and methane yield (148–309 mL/g VS fed) at all WRRs, with the optimal WRR for maximum methane production being 100 mL/d. R1 maintained more stable methanation performance than R2, possibly due to the different surface properties (i.e., biomass retention capacity) of the filter media. Such an effect was also noted in the different behaviors of the LBR and AF between R1 and R2. The molecular analysis results revealed that the development of the microbial community structure in the reactors was primarily determined by the fermentation type, i.e., dry (LBR) or wet (AF). PMID:29701670

Effectiveness of an anaerobic granular activated carbon fluidized-bed bioreactor to treat soil wash fluids: a proposed strategy for remediating PCP/PAH contaminated soils.

PubMed

Koran, K M; Suidan, M T; Khodadoust, A P; Sorial, G A; Brenner, R C

2001-07-01

An integrated system has been developed to remediate soils contaminated with pentachlorophenol (PCP) and polycyclic aromatic hydrocarbons (PAHs). This system involves the coupling of two treatment technologies, soil-solvent washing and anaerobic biotreatment of the extract. Specifically, this study evaluated the effectiveness of a granular activated carbon (GAC) fluidized-bed reactor to treat a synthetic-waste stream of PCP and four PAHs (naphthalene, acenaphthene, pyrene, and benzo(b)fluoranthene) under anaerobic conditions. This waste stream was intended to simulate the wash fluids from a soil washing process treating soils from a wood-preserving site. The reactor achieved a removal efficiency of greater than 99.8% for PCP with conversion to its dechlorination intermediates averaging 46.5%. Effluent, carbon extraction, and isotherm data also indicate that naphthalene and acenaphthene were removed from the liquid phase with efficiencies of 86 and 93%, respectively. Effluent levels of pyrene and benzo(b)fluoranthene were extremely low due to the high-adsorptive capacity of GAC for these compounds. Experimental evidence does not suggest that the latter two compounds were biochemically transformed within the reactor.

Characterization of biofilm in 200W fluidized bed reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Michelle H.; Saurey, Sabrina D.; Lee, Brady D.

2014-09-29

Contaminated groundwater beneath the 200 West Area at the Hanford Site in Southeast Washington is currently being treated using a pump and treat system to remove organics, inorganics, radionuclides, and metals. A granular activated carbon-based fluidized bed reactor (FBR) has been added to remove nitrate, hexavalent chromium and carbon tetrachloride. Initial analytical results indicated the microorganisms effectively reduced many of the contaminants to less than cleanup levels. However shortly thereafter operational upsets of the FBR include carbon carry over, over production of microbial extracellular polymeric substance (biofilm) materials, and over production of hydrogen sulfide. As a result detailed investigations weremore » undertaken to understand the functional diversity and activity of the microbial community present in the FBR over time. Molecular analyses including terminal restriction fragment length polymorphism analysis, quantitative polymerase chain reaction and fluorescent in situ hybridization analyses were performed on the microbial community extracted from the biofilm within the bed and from the inoculum, to determine functional dynamics of the FBR bed over time and following operational changes. Findings from these analyses indicated: 1) the microbial community within the bed was completely different than community used for inoculation, and was likely from the groundwater; 2) analyses early in the testing showed an FBR community dominated by a few Curvibacter and Flavobacterium species; 3) the final sample taken indicated that the microbial community in the FBR bed had become more diverse; and 4) qPCR analyses indicated that bacteria involved in nitrogen cycling, including denitrifiers and anaerobic ammonia oxidizing bacteria, were dominant in the bed. These results indicate that molecular tools can be powerful for determining functional diversity within FBR type reactors. Coupled with micronutrient, influent and effluent chemistry evaluations, a more complete understanding of the balance between system additions (nutrients, groundwater) and biology can be achieved, thus increasing long-term predictions of performance. These analyses uniquely provide information that can be used in optimizing the overall performance, efficiency, and stability of the system both in real time as well as over the long-term, as the system design is altered or improved and/or new streams are added.« less

Ultra-High Temperature ContinuousReactors based on Electro-thermal FluidizedBed Concept

DOE PAGES

Fedorov, Sergiy S.; Rohatgi, Upendra Singh; Barsukov, Igor V.; ...

2015-12-08

This paper presents the results of research and development in high-temperature (i.e. 2,000- 3,000ºС) continuous furnaces operating on the principle of electro-thermal fluidized bed for the purification of recycled, finely sized carbon materials. The basis of this fluidized bed furnace is specific electrical resistance and a new correlation has been developed to predict specific electrical resistance for the natural graphite-based precursors entering the fluidized bed reactor This correlation has been validated with the data from a fully functional pilot furnace whose throughput capacity is 10 kg per hour built as part of this work. Data collected in the course ofmore » graphite refining experiments demonstrated that difference between the calculated and measured values of specific electrical resistance of fluidized bed does not exceed 25%. It was concluded that due to chaotic nature of electro-thermal fluidized bed reactors this discrepancy is acceptable. The fluid mechanics of the three types of operating regimes, have been described. The numerical relationships obtained as part of this work allowed proposing an algorithm for selection of technological operational modes with large- scale high-temperature furnaces rated for throughputs of several tons of product per hour. Optimizations proposed now allow producing natural graphite-based end product with the purity level of 99.98+ wt%C which is the key passing criteria for applications in the advanced battery markets.« less

Deep particle bed dryout model based on flooding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuan, P.

1987-01-01

Examination of the damaged Three Mile island Unit 2 (TMI-2) reactor indicates that a deep (approx. 1-m) bed of relatively large (approx. 1-mm) particles was formed in the core. Cooling of such beds is crucial to the arrest of core damage progression. The Lipinski model, based on flows in the bed, has been used to predict the coolability, but uncertainties exist in the turbulent permeability. Models based on flooding at the top of the bed either have a dimensional viscosity term, or no viscosity dependence, thus limiting their applicability. This paper presents a dimensionless correlation based on flooding data thatmore » involves a liquid Reynolds number. The derived dryout model from this correlation is compared with data for deep beds of large particles at atmospheric pressure, and with other models over a wide pressure range. It is concluded that the present model can give quite accurate predictions for the dryout heat flux of particle beds formed during a light water reactor accident and it is easy to use and agrees with the Lipinski n = 5 model, which requires iterative calculations.« less

Gas-Liquid Packed Bed Reactors in Microgravity

NASA Technical Reports Server (NTRS)

Balakotaiah, Vemuri; Motil, Brian J.; McCready, Mark J.; Kamotani, Yasuhiro

2004-01-01

Flow regime and pressure drop data was obtained and analyzed. Pulse flow exists at lower liquid flow rates in 0-g compared to 1-g. 1-g flow regime maps do not apply in microgravity. Pressure drop is higher in microgravity (enhanced interfacial effects).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yung, Matthew M.; Stanton, Alexander R.; Iisa, Kristiina

Metal-impregnated (Ni or Ga) ZSM-5 catalysts were studied for biomass pyrolysis vapor upgrading to produce hydrocarbons using three reactors constituting a 100 000x change in the amount of catalyst used in experiments. Catalysts were screened for pyrolysis vapor phase upgrading activity in two small-scale reactors: (i) a Pyroprobe with a 10 mg catalyst in a fixed bed and (ii) a fixed-bed reactor with 500 mg of catalyst. The best performing catalysts were then validated with a larger scale fluidized-bed reactor (using ~1 kg of catalyst) that produced measurable quantities of bio-oil for analysis and evaluation of mass balances. Despite somemore » inherent differences across the reactor systems (such as residence time, reactor type, analytical techniques, mode of catalyst and biomass feed) there was good agreement of reaction results for production of aromatic hydrocarbons, light gases, and coke deposition. Relative to ZSM-5, Ni or Ga addition to ZSM-5 increased production of fully deoxygenated aromatic hydrocarbons and light gases. In the fluidized bed reactor, Ga/ZSM-5 slightly enhanced carbon efficiency to condensed oil, which includes oxygenates in addition to aromatic hydrocarbons, and reduced oil oxygen content compared to ZSM-5. Ni/ZSM-5, while giving the highest yield of fully deoxygenated aromatic hydrocarbons, gave lower overall carbon efficiency to oil but with the lowest oxygen content. Reaction product analysis coupled with fresh and spent catalyst characterization indicated that the improved performance of Ni/ZSM-5 is related to decreasing deactivation by coking, which keeps the active acid sites accessible for the deoxygenation and aromatization reactions that produce fully deoxygenated aromatic hydrocarbons. The addition of Ga enhances the dehydrogenation activity of the catalyst, which leads to enhanced olefin formation and higher fully deoxygenated aromatic hydrocarbon yields compared to unmodified ZSM-5. Catalyst characterization by ammonia temperature programmed desorption, surface area measurements, and postreaction temperature-programmed oxidation (TPO) also showed that the metal-modified zeolites retained a greater percentage of their initial acidity and surface area, which was consistent between the reactor scales. These results demonstrate that the trends observed with smaller (milligram to gram) catalyst reactors are applicable to larger, more industrially relevant (kg) scales to help guide catalyst research toward application.« less

JPRS Report, Science & Technology, China: Energy

DTIC Science & Technology

1988-06-29

capacity. There are currently two types of HTGR reactor designs: the particle-bed core , which uses spherical fuel elements, and the rod type core , in...and trial operating experience with the HTGR reactor. Its main design features are as follows. 1. A particle-bed core , continuous fueling and...Favorable for Development of Small-Scale HTGR (Xu Jiming; HE DONGLI GONGCHENG, Feb 88) 47 ERRATUM: In JPRS-CEN-88-003 of 25 April 1988 in article

A New Innovative Spherical Cermet Nuclear Fuel Element to Achieve an Ultra-Long Core Life for use in Grid-Appropriate LWRs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Senor, David J.; Painter, Chad L.; Geelhood, Ken J.

2007-12-01

Spherical cermet fuel elements are proposed for use in the Atoms For Peace Reactor (AFPR-100) concept. AFPR-100 is a small-scale, inherently safe, proliferation-resistant reactor that would be ideal for deployment to nations with emerging economies that decide to select nuclear power for the generation of carbon-free electricity. The basic concept of the AFPR core is a water-cooled fixed particle bed, randomly packed with spherical fuel elements. The flow of coolant within the particle bed is at such a low rate that the bed does not fluidize. This report summarizes an approach to fuel fabrication, results associated with fuel performance modeling,more » core neutronics and thermal hydraulics analyses demonstrating a ~20 year core life, and a conclusion that the proliferation resistance of the AFPR reactor concept is high.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.

This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO 2, and halogen species were introduced through the burner to produce a radical pool representativemore » of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO 2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO 2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO 2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO 2, and NO 2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and intraparticle diffusion. The Freundlich isotherm more accurately described in-flight mercury capture. Using these parameters, very little intraparticle diffusion was evident. Consistent with other data, smaller particles resulted in higher mercury uptake due to available surface area. Therefore, it is important to capture the particle size distribution in the model. At typical full-scale sorbent feed rates, the calculations under-predicted adsorption, suggesting that wall effects can account for as much as 50 percent of the removal, making it an important factor in entrained-mercury adsorption models.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.

This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO 2, and halogen species were introduced through the burner to produce a radical pool representativemore » of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO 2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO 2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO 2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO 2, and NO 2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and intraparticle diffusion. The Freundlich isotherm more accurately described in-flight mercury capture. Using these parameters, very little intraparticle diffusion was evident. Consistent with other data, smaller particles resulted in higher mercury uptake due to available surface area. Therefore, it is important to capture the particle size distribution in the model. At typical full-scale sorbent feed rates, the calculations underpredicted adsorption, suggesting that wall effects can account for as much as 50 percent of the removal, making it an important factor in entrained-mercury adsorption models.« less

Complexity and Challenges in Noncontact High Temperature Measurements in Microwave-Assisted Catalytic Reactors

PubMed Central

2017-01-01

The complexity and challenges in noncontact temperature measurements inside microwave-heated catalytic reactors are presented in this paper. A custom-designed microwave cavity has been used to focus the microwave field on the catalyst and enable monitoring of the temperature field in 2D. A methodology to study the temperature distribution in the catalytic bed by using a thermal camera in combination with a thermocouple for a heterogeneous catalytic reaction (methane dry reforming) under microwave heating has been demonstrated. The effects of various variables that affect the accuracy of temperature recordings are discussed in detail. The necessity of having at least one contact sensor, such as a thermocouple, or some other microwave transparent sensor, is recommended to keep track of the temperature changes occurring in the catalytic bed during the reaction under microwave heating. PMID:29170599

Fluidized bed gasification of industrial solid recovered fuels.

PubMed

Arena, Umberto; Di Gregorio, Fabrizio

2016-04-01

The study evaluates the technical feasibility of the fluidized bed gasification of three solid recovered fuels (SRFs), obtained as co-products of a recycling process. The SRFs were pelletized and fed to a pilot scale bubbling fluidized bed reactor, operated in gasification and co-gasification mode. The tests were carried out under conditions of thermal and chemical steady state, with a bed of olivine particles and at different values of equivalence ratio. The results provide a complete syngas characterization, in terms of its heating value and composition (including tars, particulates, and acid/basic pollutants) and of the chemical and physical characterization of bed material and entrained fines collected at the cyclone outlet. The feasibility of the fluidized bed gasification process of the different SRFs was evaluated with the support of a material and substance flow analysis, and a feedstock energy analysis. The results confirm the flexibility of fluidized bed reactor, which makes it one of the preferable technologies for the gasification of different kind of wastes, even in co-gasification mode. The fluidized bed gasification process of the tested SRFs appears technically feasible, yielding a syngas of valuable quality for energy applications in an appropriate plant configuration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigation of flow dynamics of liquid phase in a pilot-scale trickle bed reactor using radiotracer technique.

PubMed

Pant, H J; Sharma, V K

2016-10-01

A radiotracer investigation was carried out to measure residence time distribution (RTD) of liquid phase in a trickle bed reactor (TBR). The main objectives of the investigation were to investigate radial and axial mixing of the liquid phase, and evaluate performance of the liquid distributor/redistributor at different operating conditions. Mean residence times (MRTs), holdups (H) and fraction of flow flowing along different quadrants were estimated. The analysis of the measured RTD curves indicated radial non-uniform distribution of liquid phase across the beds. The overall RTD of the liquid phase, measured at the exit of the reactor was simulated using a multi-parameter axial dispersion with exchange model (ADEM), and model parameters were obtained. The results of model simulations indicated that the TBR behaved as a plug flow reactor at most of the operating conditions used in the investigation. The results of the investigation helped to improve the existing design as well as to design a full-scale industrial TBR for petroleum refining applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Experimental and Computational Study of the Hydrodynamics of Trickle Bed Flow Reactor Operating Under Different Pressure Conditions

NASA Astrophysics Data System (ADS)

Rabbani, S.; Ben Salem, I.; Nadeem, H.; Kurnia, J. C.; Shamim, T.; Sassi, M.

2014-12-01

Pressure drop estimation and prediction of liquid holdup play a crucial role in design and operation of trickle bed reactors. Experiments are performed for Light Gas Oil (LGO)-nitrogen system in ambient temperature conditions in an industrial pilot plant with reactor height 0.79 m and diameter of 0.0183 m and pressure ranging from atmospheric to 10 bars. It was found that pressure drop increased with increase in system pressure, superficial gas velocity and superficial liquid velocity. It was demonstrated in the experiments that liquid holdup of the system increases with the increase in superficial liquid velocity and tends to decrease with increase in superficial gas velocity which is in good agreement with existing literature. Similar conditions were also simulated using CFD-software FLUENT. The Volume of Fluid (VoF) technique was employed in combination with "discrete particle approach" and results were compared with that of experiments. The overall pressure drop results were compared with the different available models and a new comprehensive model was proposed to predict the pressure drop in Trickle Bed Flow Reactor.

Remediation of trichloroethylene by bio-precipitated and encapsulated palladium nanoparticles in a fixed bed reactor.

PubMed

Hennebel, Tom; Verhagen, Pieter; Simoen, Henri; De Gusseme, Bart; Vlaeminck, Siegfried E; Boon, Nico; Verstraete, Willy

2009-08-01

Trichloroethylene is a toxic and recalcitrant groundwater pollutant. Palladium nanoparticles bio-precipitated on Shewanella oneidensis were encapsulated in polyurethane, polyacrylamide, alginate, silica or coated on zeolites. The reactivity of these bio-Pd beads and zeolites was tested in batch experiments and trichloroethylene dechlorination followed first order reaction kinetics. The calculated k-values of the encapsulated catalysts were a factor of six lower compared to non-encapsulated bio-Pd. Bio-Pd, used as a catalyst, was able to dechlorinate 100 mgL(-1) trichloroethylene within a time period of 1h. The main reaction product was ethane; yet small levels of chlorinated intermediates were detected. Subsequently polyurethane cubes empowered with bio-Pd were implemented in a fixed bed reactor for the treatment of water containing trichloroethylene. The influent recycle configuration resulted in a cumulative removal of 98% after 22 h. The same reactor in a flow through configuration achieved removal rates up to 1059 mg trichloroethylene g Pd(-1)d(-1). This work showed that fixed bed reactors with bio-Pd polyurethane cubes can be instrumental for remediation of water contaminated with trichloroethylene.

Enhanced biofiltration using cell attachment promotors.

PubMed

Goncalves, Juan J; Govind, Rakesh

2009-02-15

H2S polluted airstreams were treated in two biotrickling filter columns packed with polyurethane (PU) foam cubes, one with cubes coated with a solution of 25 mg/L of polyethyleneimine (PEI, coated reactor) and the other containing just plain PU cubes (uncoated reactor) at empty bed residence times (EBRT) ranging from 6 to 60 s. and inlet H2S concentrations ranging from 30 to 235 ppm, (overall loads of up to 44 gH2S/m3bed/h), with overall removal efficiencies (RE) in the range of 90-100% over 125 days. The acclimatization characteristics of the coated reactor outperformed those of the uncoated one, and both the observed elimination capacity (EC) of 77 gH2S/m3bed/h and retention of volatile solids (VS) of 42 mgVS/cube were maxima in the coated reactor. Insights into the controlling removal mechanisms were also provided by means of dimensionless analysis of the experimental data. Denaturing gradient gel electrophoresis (DGGE) showed that the dominant surviving species in both units belonged to the genus Acidithiobacillus.

Steam-air blown bubbling fluidized bed biomass gasification (BFBBG): Multi-scale models and experimental validation

DOE PAGES

Bates, Richard B.; Ghoniem, Ahmed F.; Jablonski, Whitney S.; ...

2017-02-02

During fluidized bed biomass gasification, complex gas-solid mixing patterns and numerous chemical and physical phenomena make identification of optimal operating conditions challenging. In this work, a parametric experimental campaign was carried out alongside the development of a coupled reactor network model which successfully integrates the individually validated sub-models to predict steady-state reactor performance metrics and outputs. The experiments utilized an integrated gasification system consisting of an externally-heated, bench-scale, 4-in., 5 kWth, fluidized bed steam/air blown gasifier fed with woody biomass equipped with a molecular beam mass spectrometer to directly measure tar species. The operating temperature (750-850°C) and air/fuel equivalence ratiomore » (ER = 0-0.157) were independently varied to isolate their effects. Elevating temperature is shown to improve the char gasification rate and reduce tar concentrations. In conclusion, air strongly impacts the composition of tar, accelerating the conversion of lighter polycyclic-aromatic hydrocarbons into soot precursors, while also improving the overall carbon conversion.« less

Comparison of bioreactors with different kinds of submerged packed beds for domestic wastewater treatment.

PubMed

Nacheva, P Mijaylova; Moeller Chávez, G; Bustos, C; Garzón Zúñiga, M A; Hornelas Orozco, Y

2008-01-01

The performance of aerobic submerged packed bed reactors was studied for the treatment of domestic wastewater using different kinds of packing materials with high specific areas (760-1,200 m(2)/m(3)). The tested materials were ceramic spheres, crushed tezontle, grains of high density polyethylene (HDPE), of low density polyethylene (LDPE) and of polypropylene (PP), cubes of polyurethane (PU) and polyethylene tape (SESSIL). The bioreactors were operated in continuous regime, applying organic loads in the range of 0.8-6.0 g COD.m(-2).d(-1). The obtained specific COD removal rates were very similar in all the reactors when they were operated at organic loads up to 2.0 g COD.m(-2).d(-1), after which differences in effectiveness appeared and the best results were determined in the reactors with SESSIL, LDPE and PU. Very low TSS, O&G and turbidity were obtained in all the effluents. The NH(3)-N and TN removals were dependent on the dissolved oxygen (DO) concentration and the removals at DO of 5 mg/l were 84-99% and 61-74% respectively. The best removals were determined in the reactors with PU, SESSIL and LDPE. The reactor with tezontle had also a good performance when operated with loads up to 1.0 g TN.m(-2).d(-1). The best phosphate removals (38-49%) were obtained in the reactors with PU, tezontle, ceramic sheres and SESSIL. (c) IWA Publishing 2008.

Polypropylene Production Optimization in Fluidized Bed Catalytic Reactor (FBCR): Statistical Modeling and Pilot Scale Experimental Validation

PubMed Central

Khan, Mohammad Jakir Hossain; Hussain, Mohd Azlan; Mujtaba, Iqbal Mohammed

2014-01-01

Propylene is one type of plastic that is widely used in our everyday life. This study focuses on the identification and justification of the optimum process parameters for polypropylene production in a novel pilot plant based fluidized bed reactor. This first-of-its-kind statistical modeling with experimental validation for the process parameters of polypropylene production was conducted by applying ANNOVA (Analysis of variance) method to Response Surface Methodology (RSM). Three important process variables i.e., reaction temperature, system pressure and hydrogen percentage were considered as the important input factors for the polypropylene production in the analysis performed. In order to examine the effect of process parameters and their interactions, the ANOVA method was utilized among a range of other statistical diagnostic tools such as the correlation between actual and predicted values, the residuals and predicted response, outlier t plot, 3D response surface and contour analysis plots. The statistical analysis showed that the proposed quadratic model had a good fit with the experimental results. At optimum conditions with temperature of 75°C, system pressure of 25 bar and hydrogen percentage of 2%, the highest polypropylene production obtained is 5.82% per pass. Hence it is concluded that the developed experimental design and proposed model can be successfully employed with over a 95% confidence level for optimum polypropylene production in a fluidized bed catalytic reactor (FBCR). PMID:28788576

Biological floating bed and bio-contact oxidation processes for landscape water treatment: simultaneous removal of Microcystis aeruginosa, TOC, nitrogen and phosphorus.

PubMed

Su, Jun Feng; Liang, Dong Hui; Fu, Le; Wei, Li; Ma, Min

2018-06-13

The aim of this study was to identify algicidal bacteria J25 against the Microcystis aeruginosa (90.14%), Chlorella (78.75%), Scenedesmus (not inhibited), and Oscillatoria (90.12%). Meanwhile, we evaluate the SOD activity and efficiency of denitrification characteristics with Acinetobacter sp. J25. A novel hybrid bioreactor combined biological floating bed with bio-contact oxidation (BFBO) was designed for treating the landscape water, and the average removal efficiencies of nitrate-N, ammonia-N, nitrite-N, TN, TP, TOC, and algal cells were 91.14, 50, 87.86, 88.83, 33.07, 53.95, and 53.43%, respectively. A 454-pyrosequencing technology was employed to investigate the microbial communities of the BFBO reactor samples. The results showed that Acinetobacter sp. J25 was the dominant contributor for effective removal of N, algal cells, and TOC in the BFBO reactor. And the relative abundance of Acinetobacter showed increase trend with the delay of reaction time. Graphical abstract Biological floating bed and bio-contact oxidation (BFBO) as a novel hybrid bioreactor designed for simultaneous removal Microcystis aeruginosa, TOC, nitrogen, and phosphorus. And high-throughput sequencing data demonstrated that Acinetobacter sp. J25 was the dominate species in the reactor and played key roles in the removal of N, TOC, and M. aeruginosa. Proposed reaction mechanism of the BFBO.

Lewis Pressurized, Fluidized-Bed Combustion Program. Data and Calculated Results

NASA Technical Reports Server (NTRS)

Rollbuhler, R. J.

1982-01-01

A 200 kilowatt (thermal), pressurized, fluidized bed (PFB) reactor and research test facility were designed, constructed, and operated. The facility was established to assess and evaluate the effect of PFB hot gas effluent on aircraft turbine engine materials that may have applications in stationary powerplant turbogenerators. The facility was intended for research and development work and was designed to operate over a wide range of conditions. These conditions included the type and rate of consumption of fuel (e.g., coal) and sulfur reacting sorbent material: the ratio of feed fuel to sorbent material; the ratio of feed fuel to combustion airflow; the depth of the fluidized reaction bed; the temperature and pressure in the reaction bed; and the type of test unit that was exposed to the combustion exhaust gases.

Lewis pressurized, fluidized-bed combustion program. Data and calculated results

NASA Astrophysics Data System (ADS)

Rollbuhler, R. J.

1982-03-01

A 200 kilowatt (thermal), pressurized, fluidized bed (PFB) reactor and research test facility were designed, constructed, and operated. The facility was established to assess and evaluate the effect of PFB hot gas effluent on aircraft turbine engine materials that may have applications in stationary powerplant turbogenerators. The facility was intended for research and development work and was designed to operate over a wide range of conditions. These conditions included the type and rate of consumption of fuel (e.g., coal) and sulfur reacting sorbent material: the ratio of feed fuel to sorbent material; the ratio of feed fuel to combustion airflow; the depth of the fluidized reaction bed; the temperature and pressure in the reaction bed; and the type of test unit that was exposed to the combustion exhaust gases.

Validating the MFiX-DEM Model for Flow Regime Prediction in a 3D Spouted Bed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Subhodeep; Guenther, Chris; Rogers, William A.

The spout-fluidized bed reactor with relatively large oxygen carrier particles offers several advantages in chemical looping combustion operation using solid fuels. The large difference in size and weight between the oxygen carrier particles and the smaller coal or ash particles allows the oxygen carrier to be easily segregated for recirculation; the increased solids mixing due to dynamic flow pattern in the spout-fluidization regime prevents agglomeration. The primary objective in this work is to determine the effectiveness of the MFiX-DEM model in predicting the flow regime in a spouted bed. Successful validation of the code will allow the user to finemore » tune the operating conditions of a spouted bed to achieve the desired operating condition.« less

Production and optimization of biodiesel using mixed immobilized biocatalysts in packed bed reactor.

PubMed

Bakkiyaraj, S; Syed, Mahin Basha; Devanesan, M G; Thangavelu, Viruthagiri

2016-05-01

Vegetable oils are used as raw materials for biodiesel production using transesterification reaction. Several methods for the production of biodiesel were developed using chemical (alkali and acidic compounds) and biological catalysts (lipases). Biodiesel production catalyzed by lipases is energy and cost-saving processes and is carried out at normal temperature and pressure. The need for an efficient method for screening larger number of variables has led to the adoption of statistical experimental design. In the present study, packed bed reactor was designed to study with mixed immobilized biocatalysts to have higher productivity under optimum conditions. Contrary to the single-step acyl migration mechanism, a two-step stepwise reaction mechanism involving immobilized Candida rugosa lipase and immobilized Rhizopus oryzae cells was employed for the present work. This method was chosen because enzymatic hydrolysis followed by esterification can tolerate high free fatty acid containing oils. The effects of flow rate and bed height on biodiesel yield were studied using two factors five-level central composite design (CCD) and response surface methodology (RSM). Maximum biodiesel yield of 85 and 81 % was obtained for jatropha oil and karanja oil with the optimum bed height and optimum flow rate of 32.6 cm and 1.35 L/h, and 32.6 cm and 1.36 L/h, respectively.

Bed Agglomeration During the Steam Gasification of a High Lignin Corn Stover Simultaneous Saccharification and Fermentation (SSF) Digester Residue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howe, Daniel T.; Taasevigen, Danny J.; Gerber, Mark A.

This research investigates the bed agglomeration phenomena during the steam gasification of a high lignin residue produced from the simultaneous saccharification and fermentation (SSF) of corn stover in a bubbling fluidized bed. The studies were conducted at 895°C using alumina as bed material. Biomass was fed at 1.5 kg/hr, while steam was fed to give a velocity equal to 2.5 times the minimum fluidization velocity, with a steam/carbon ratio of 0.9. The pelletized feedstock was co-fed with a cooling nitrogen stream to mitigate feed line plugging issues. Tar production was high at 50.3 g/Nm3, and the fraction of C10+ compoundsmore » was greater than that seen in the gasification of traditional lignocellulosic feedstocks. Carbon closures over 94 % were achieved for all experiments. Bed agglomeration was found to be problematic, indicated by pressure drop increases observed below the bed and upstream of the feed line. Two size categories of solids were recovered from the reactor, +60 mesh and -60 mesh. After a 2.75-hour experiment, 61.7 wt % was recovered as -60 mesh particles and 38.2 wt% of the recovered reactor solids were +60 mesh. A sizeable percentage, 31.8 wt%, was +20 mesh. The -60 mesh particles were mainly formed by the initial bed material (Al2O3). Almost 50 wt. % of the + 20 mesh particles was found to be formed by organics. The unreacted carbon remaining in the reactor resulted in a low conversion rate to product gas. ICP-AES, SEM, SEM-EDS, and XRD confirmed that the large agglomerates (+ 20 mesh) were not encapsulated bed material but rather un-gasified feedstock pellets with sand particles attached to it.« less

Method of feeding particulate material to a fluidized bed

DOEpatents

Borio, Richard W.; Goodstine, Stephen L.

1984-01-01

A centrifugal spreader type feeder that supplies a mixture of particulate limestone and coal to the top of a fluidized bed reactor having a flow of air upward therethrough. Large particles of particulate matter are distributed over the upper surface of the bed to utilize the natural mixing within the bed, while fine particles are adapted to utilize an independent feeder that separates them from the large particles and injects them into the bed.

Effect of temperature, hydraulic residence time and elevated PCO2 on acid neutralization within a pulsed limestone bed reactor

USGS Publications Warehouse

Watten, B.J.; Lee, P.C.; Sibrell, P.L.; Timmons, M.B.

2007-01-01

Limestone has potential for reducing reagent costs and sludge volume associated with treatment of acid mine drainage, but its use is restricted by slow dissolution rates and the deposition of Fe, Al and Mn-based hydrolysis products on reactive surfaces. We evaluated a pulsed limestone bed (PLB) reactor (15 L/min capacity) that uses a CO2 pretreatment step to accelerate dissolution and hydraulic shearing forces provided by intermittent fluidization to abrade and carry away surface scales. We established the effects of hydraulic residence time (HRT, 5.1-15.9 min), temperature (T, 12-22 ??C) and CO2 tension (PCO2, 34.5-206.8 kPa) on effluent quality when inlet acidity (Acy) was fixed at 440 mg/L (pH=2.48) with H2SO4. The PLB reactor neutralized all H+ acidity (N=80) while concurrently providing unusually high levels of effluent alkalinity (247-1028 mg/L as CaCO3) that allow for side-stream treatment with blending. Alkalinity (Alk) yields rose with increases in PCO2, HRT and settled bed height (BH, cm) and decreased with T following the relationship (R2=0.926; p<0.001): (Alk)non-filtered=-548.726+33.571??(PCO2)0.5+33.671??(HRT)+7.734??(BH)-5.197??(T). Numerical modeling showed CO2 feed requirements for a target Alk yield decrease with increases in HRT, T and the efficiency of off-gas (CO2) recycling. ?? 2007 Elsevier Ltd. All rights reserved.

A New Dry Flue Gas Desulfurization Process-Underfeed Circulating Spouted Bed

NASA Astrophysics Data System (ADS)

Tao, M.; Jin, B. S.; Yang, Y. P.

Applying an underfeed system, the underfeed circulating spouted bed was designed as a desulfurization reactor. The main objective of the technology is to improve the mixing effect and distribution uniformity of solid particles, and therefore to advance the desulfurization efficiency and calcium utility. In this article, a series of experimental studies were conducted to investigate the fluidization behavior of the solid-gas two-phase flow in the riser. The results show that the technology can distinctly improve the distribution of gas velocity and particle flux on sections compared with the facefeed style. Analysis of pressure fluctuation signals indicates that the operation parameters have significant influence on the flow field in the reaction bed. The existence of injecting flow near the underfeed nozzle has an evident effect on strengthening the particle mixing.

Development of an In-Situ Decommissioning Sensor Network Test Bed for Structural Condition Monitoring - 12156

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeigler, Kristine E.; Ferguson, Blythe A.

2012-07-01

The Savannah River National Laboratory (SRNL) has established an In Situ Decommissioning (ISD) Sensor Network Test Bed, a unique, small scale, configurable environment, for the assessment of prospective sensors on actual ISD system material, at minimal cost. The Department of Energy (DOE) is presently implementing permanent entombment of contaminated, large nuclear structures via ISD. The ISD end state consists of a grout-filled concrete civil structure within the concrete frame of the original building. Validation of ISD system performance models and verification of actual system conditions can be achieved through the development a system of sensors to monitor the materials andmore » condition of the structure. The ISD Sensor Network Test Bed has been designed and deployed to addresses the DOE-Environmental Management Technology Need to develop a remote monitoring system to determine and verify ISD system performance. Commercial off-the-shelf sensors have been installed on concrete blocks taken from walls of the P Reactor Building at the Savannah River Site. Deployment of this low-cost structural monitoring system provides hands-on experience with sensor networks. The initial sensor system consists of groutable thermistors for temperature and moisture monitoring, strain gauges for crack growth monitoring, tilt-meters for settlement monitoring, and a communication system for data collection. Baseline data and lessons learned from system design and installation and initial field testing will be utilized for future ISD sensor network development and deployment. The Sensor Network Test Bed at SRNL uses COTS sensors on concrete blocks from the outer wall of the P Reactor Building to measure conditions expected to occur in ISD structures. Knowledge and lessons learned gained from installation, testing, and monitoring of the equipment will be applied to sensor installation in a meso-scale test bed at FIU and in future ISD structures. The initial data collected from the sensors installed on the P Reactor Building blocks define the baseline materials condition of the P Reactor ISD external concrete structure. Continued monitoring of the blocks will enable evaluation of the effects of aging on the P Reactor ISD structure. The collected data will support validation of the material degradation model and assessment of the condition of the ISD structure over time. The following are recommendations for continued development of the ISD Sensor Network Test Bed: - Establish a long-term monitoring program using the concrete blocks with existing sensor and/or additional sensors for trending the concrete materials and structural condition; - Continue development of a stand-alone test bed sensor system that is self-powered and provides wireless transmission of data to a user-accessible dashboard; - Develop and implement periodic NDE/DE characterization of the concrete blocks to provide verification and validation for the measurements obtained through the sensor system and concrete degradation model(s). (authors)« less

Catalytic pyrolysis of Alcea pallida stems in a fixed-bed reactor for production of liquid bio-fuels.

PubMed

Aysu, Tevfik

2015-09-01

Pyrolysis of Alcea pallida stems was performed in a fixed-bed tubular reactor with and without catalyst at three different temperatures. The effects of pyrolysis parameters including temperature and catalyst on the product yields were investigated. It was found that higher temperature resulted in lower liquid (bio-oil) and solid (bio-char) yields and higher gas yields. Catalysts had different effects on product yields and composition of bio-oils. Liquid yields were increased in the presence of zinc chloride and alumina but decreased with calcium hydroxide, tincal and ulexite. The highest bio-oil yield (39.35%) by weight including aqueous phase was produced with alumina catalyst at 500 °C. The yields of bio-char, bio-oil and gas produced, as well as the compositions of the resulting bio-oils were determined by elemental analysis, TGA, FT-IR and GC-MS. 160 different compounds were identified by GC-MS in the bio-oils obtained at 500 °C. Copyright © 2015 Elsevier Ltd. All rights reserved.

Model Studies on the Effectiveness of MBBR Reactors for the Restoration of Small Water Reservoirs

NASA Astrophysics Data System (ADS)

Nowak, Agata; Mazur, Robert; Panek, Ewa; Chmist, Joanna

2018-02-01

The authors present the Moving Bed Biofilm Reactor (MBBR) model with a quasi-continuous flow for small water reservoir restoration, characterized by high concentrations of organic pollutants. To determine the efficiency of wastewater treatment the laboratory analysis of physic-chemical parameters were conducted for the model on a semi-technical scale of 1:3. Wastewater treatment process was carried out in 24 h for 1 m3 for raw sewage. The startup period was 2 weeks for all biofilters (biological beds). Approximately 50% reduction in COD and BOD5 was obtained on average for the studied bioreactors. Significant improvements were achieved in theclarity of the treated wastewater, with the reduction of suspension by 60%. The oxygen profile has improved significantly in 7 to 9 hours of the process, and a diametric reduction in the oxidative reduction potential was recorded. A preliminary model of biological treatment effectiveness was determined based on the conducted studies. In final stages, the operation mode was set in real conditions of polluted water reservoirs.

Treatment of ammonia by catalytic wet oxidation process over platinum-rhodium bimetallic catalyst in a trickle-bed reactor: effect of pH.

PubMed

Hung, Chang-Mao; Lin, Wei-Bang; Ho, Ching-Lin; Shen, Yun-Hwei; Hsia, Shao-Yi

2010-08-01

This work adopted aqueous solutions of ammonia for use in catalytic liquid-phase reduction in a trickle-bed reactor with a platinum-rhodium bimetallic catalyst, prepared by the co-precipitation of chloroplatinic acid (H2PtCl6) and rhodium nitrate [Rh(NO3)3]. The experimental results demonstrated that a minimal amount of ammonia was removed from the solution by wet oxidation in the absence of any catalyst, while approximately 97.0% of the ammonia was removed by wet oxidation over the platinum-rhodium bimetallic catalyst at 230 degrees C with an oxygen partial pressure of 2.0 MPa. The oxidation of ammonia has been studied as a function of pH, and the main reaction products were determined. A synergistic effect is manifest in the platinum-rhodium bimetallic structure, in which the material has the greatest capacity to reduce ammonia. The reaction pathway linked the oxidizing ammonia to nitric oxide, nitrogen, and water.

Production of biohythane from food waste via an integrated system of continuously stirred tank and anaerobic fixed bed reactors.

PubMed

Yeshanew, Martha M; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

2016-11-01

The continuous production of biohythane (mixture of biohydrogen and methane) from food waste using an integrated system of a continuously stirred tank reactor (CSTR) and anaerobic fixed bed reactor (AFBR) was carried out in this study. The system performance was evaluated for an operation period of 200days, by stepwise shortening the hydraulic retention time (HRT). An increasing trend of biohydrogen in the CSTR and methane production rate in the AFBR was observed regardless of the HRT shortening. The highest biohydrogen yield in the CSTR and methane yield in the AFBR were 115.2 (±5.3)L H2/kgVSadded and 334.7 (±18.6)L CH4/kgCODadded, respectively. The AFBR presented a stable operation and excellent performance, indicated by the increased methane production rate at each shortened HRT. Besides, recirculation of the AFBR effluent to the CSTR was effective in providing alkalinity, maintaining the pH in optimal ranges (5.0-5.3) for the hydrogen producing bacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of selected chemical processes for production of low-cost silicon, phase 2

NASA Technical Reports Server (NTRS)

Blocher, J. M., Jr.; Browning, M. F.; Wilson, W. J.; Carmichael, D. C.

1977-01-01

Potential designs for an integrated fluidized-bed reactor/zinc vaporizer/SiCl4 preheater unit are being considered and heat-transfer calculations have been initiated on versions of the zinc vaporizer section. Estimates of the cost of the silicon prepared in the experimental facility have been made for projected capacities of 25, 50, 75, and 100 metric ton of silicon. A 35 percent saving is obtained in going from 25 metric ton/year to the 50 metric ton/year level. This analysis, coupled with the recognition that use of two reactors in the 50 metric ton/year version allows for continued operation (at reduced capacity) with one reactor shut down, has resulted in a recommendation for adoption of an experimental facility capacity of 50 metric ton/year or greater. At this stage, the change to a larger size facility would not increase the design costs appreciably. In the experimental support program, the effects of seed bed particle size and depth were studied, and operation of the miniplant with a new zinc vaporizer was initiated, revealing the need for modification of the latter.

Biodegradation of atrazine from wastewater using moving bed biofilm reactor under nitrate-reducing conditions: A kinetic study.

PubMed

Derakhshan, Zahra; Ehrampoush, Mohammad Hassan; Mahvi, Amir Hossein; Ghaneian, Mohammad Taghi; Mazloomi, Seyed Mohammad; Faramarzian, Mohammad; Dehghani, Mansooreh; Fallahzadeh, Hossein; Yousefinejad, Saeed; Berizi, Enayat; Bahrami, Shima

2018-04-15

In this study employed an anoxic moving bed biofilm reactor (AnMBBR) to evaluate the effects of hydraulic and toxic shocks on performance reactor. The results indicated a relatively good resistance of system against exercised shocks and its ability to return to steady-state conditions. In optimal conditions when there was the maximum rate of atrazine and soluble chemical oxygen demand (COD) removal were 74.82% and 99.29% respectively. Also, atrazine biodegradation rapidly declines in AnMBBR from 74% ± 0.05 in the presence of nitrate to 9.12% only 3 days after the nitrate was eliding from the influent. Coefficients kinetics was studied and the maximum atrazine removal rate was determined by modified Stover & Kincannon model (U max  = 9.87 g ATZ /m 3 d). Results showed that AnMBBR is feasible, easy, affordable, so suitable process for efficiently biodegrading toxic chlorinated organic compounds such as atrazine. Also, its removal mechanism in this system is co-metabolism. Copyright © 2018 Elsevier Ltd. All rights reserved.

Apparatus and method for solar coal gasification

DOEpatents

Gregg, David W.

1980-01-01

Apparatus for using focused solar radiation to gasify coal and other carbonaceous materials. Incident solar radiation is focused from an array of heliostats onto a tower-mounted secondary mirror which redirects the focused solar radiation down through a window onto the surface of a vertically-moving bed of coal, or a fluidized bed of coal, contained within a gasification reactor. The reactor is designed to minimize contact between the window and solids in the reactor. Steam introduced into the gasification reactor reacts with the heated coal to produce gas consisting mainly of carbon monoxide and hydrogen, commonly called "synthesis gas", which can be converted to methane, methanol, gasoline, and other useful products. One of the novel features of the invention is the generation of process steam at the rear surface of the secondary mirror.

Apparatus for solar coal gasification

DOEpatents

Gregg, D.W.

Apparatus for using focused solar radiation to gasify coal and other carbonaceous materials is described. Incident solar radiation is focused from an array of heliostats onto a tower-mounted secondary mirror which redirects the focused solar radiation down through a window onto the surface of a vertically-moving bed of coal, or a fluidized bed of coal, contained within a gasification reactor. The reactor is designed to minimize contact between the window and solids in the reactor. Steam introduced into the gasification reactor reacts with the heated coal to produce gas consisting mainly of carbon monoxide and hydrogen, commonly called synthesis gas, which can be converted to methane, methanol, gasoline, and other useful products. One of the novel features of the invention is the generation of process steam at the rear surface of the secondary mirror.

Closed Brayton Cycle power system with a high temperature pellet bed reactor heat source for NEP applications

NASA Technical Reports Server (NTRS)

Juhasz, Albert J.; El-Genk, Mohamed S.; Harper, William B., Jr.

1992-01-01

Capitalizing on past and future development of high temperature gas reactor (HTGR) technology, a low mass 15 MWe closed gas turbine cycle power system using a pellet bed reactor heating helium working fluid is proposed for Nuclear Electric Propulsion (NEP) applications. Although the design of this directly coupled system architecture, comprising the reactor/power system/space radiator subsystems, is presented in conceptual form, sufficient detail is included to permit an assessment of overall system performance and mass. Furthermore, an attempt is made to show how tailoring of the main subsystem design characteristics can be utilized to achieve synergistic system level advantages that can lead to improved reliability and enhanced system life while reducing the number of parasitic load driven peripheral subsystems.

Zone heating for fluidized bed silane pyrolysis

NASA Technical Reports Server (NTRS)

Iya, Sridhar K. (Inventor)

1987-01-01

An improved heated fluidized bed reactor and method for the production of high purity polycrystalline silicon by silane pyrolysis wherein silicon seed particles are heated in an upper heating zone of the reactor and admixed with particles in a lower reaction zone, in which zone a silane-containing gas stream, having passed through a lower cooled gas distribution zone not conducive to silane pyrolysis, contacts the heated seed particles whereon the silane is heterogeneously reduced to silicon.

Biodegradation of toluene vapor in coir based upflow packed bed reactor by Trichoderma asperellum isolate.

PubMed

Gopinath, M; Mohanapriya, C; Sivakumar, K; Baskar, G; Muthukumaran, C; Dhanasekar, R

2016-03-01

In the present study, a new biofiltration system involving a selective microbial strain isolated from aerated municipal sewage water attached with coir as packing material was developed for toluene degradation. The selected fungal isolate was identified as Trichoderma asperellum by 16S ribosomal RNA (16S rRNA) sequencing method, and pylogenetic tree was constructed using BLASTn search. Effect of various factors on growth and toluene degradation by newly isolated T. asperellum was studied in batch studies, and the optimum conditions were found to be pH 7.0, temperature 30 °C, and initial toluene concentration 1.5 (v/v)%. Continuous removal of gaseous toluene was monitored in upflow packed bed reactor (UFPBR) using T. asperellum. Effect of various parameters like column height, flow rate, and the inlet toluene concentration were studied to evaluate the performance of the biofilter. The maximum elimination capacity (257 g m(-3) h(-1)) was obtained with the packing height of 100 cm with the empty bed residence time of 5 min. Under these optimum conditions, the T. asperellum showed better toluene removal efficiency. Kinetic models have been developed for toluene degradation by T. asperellum using macrokinetic approach of the plug flow model incorporated with Monod model.

A comparison of mass transfer coefficients between trickle-bed, hollow fiber membrane and stirred tank reactors.

PubMed

Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

2013-04-01

Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Conceptual process design and techno-economic assessment of ex situ catalytic fast pyrolysis of biomass: A fixed bed reactor implementation scenario for future feasibility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, Abhijit; Schaidle, Joshua A.; Humbird, David

Ex situ catalytic fast pyrolysis of biomass is a promising route for the production of fungible liquid biofuels. There is significant ongoing research on the design and development of catalysts for this process. However, there are a limited number of studies investigating process configurations and their effects on biorefinery economics. Herein we present a conceptual process design with techno-economic assessment; it includes the production of upgraded bio-oil via fixed bed ex situ catalytic fast pyrolysis followed by final hydroprocessing to hydrocarbon fuel blendstocks. This study builds upon previous work using fluidized bed systems, as detailed in a recent design reportmore » led by the National Renewable Energy Laboratory (NREL/TP-5100-62455); overall yields are assumed to be similar, and are based on enabling future feasibility. Assuming similar yields provides a basis for easy comparison and for studying the impacts of areas of focus in this study, namely, fixed bed reactor configurations and their catalyst development requirements, and the impacts of an inline hot gas filter. A comparison with the fluidized bed system shows that there is potential for higher capital costs and lower catalyst costs in the fixed bed system, leading to comparable overall costs. The key catalyst requirement is to enable the effective transformation of highly oxygenated biomass into hydrocarbons products with properties suitable for blending into current fuels. Potential catalyst materials are discussed, along with their suitability for deoxygenation, hydrogenation and C–C coupling chemistry. This chemistry is necessary during pyrolysis vapor upgrading for improved bio-oil quality, which enables efficient downstream hydroprocessing; C–C coupling helps increase the proportion of diesel/jet fuel range product. One potential benefit of fixed bed upgrading over fluidized bed upgrading is catalyst flexibility, providing greater control over chemistry and product composition. Since this study is based on future projections, the impacts of uncertainties in the underlying assumptions are quantified via sensitivity analysis. As a result, this analysis indicates that catalyst researchers should prioritize by: carbon efficiency > catalyst cost > catalyst lifetime, after initially testing for basic operational feasibility.« less

Conceptual process design and techno-economic assessment of ex situ catalytic fast pyrolysis of biomass: A fixed bed reactor implementation scenario for future feasibility

DOE PAGES

Dutta, Abhijit; Schaidle, Joshua A.; Humbird, David; ...

2015-10-06

Ex situ catalytic fast pyrolysis of biomass is a promising route for the production of fungible liquid biofuels. There is significant ongoing research on the design and development of catalysts for this process. However, there are a limited number of studies investigating process configurations and their effects on biorefinery economics. Herein we present a conceptual process design with techno-economic assessment; it includes the production of upgraded bio-oil via fixed bed ex situ catalytic fast pyrolysis followed by final hydroprocessing to hydrocarbon fuel blendstocks. This study builds upon previous work using fluidized bed systems, as detailed in a recent design reportmore » led by the National Renewable Energy Laboratory (NREL/TP-5100-62455); overall yields are assumed to be similar, and are based on enabling future feasibility. Assuming similar yields provides a basis for easy comparison and for studying the impacts of areas of focus in this study, namely, fixed bed reactor configurations and their catalyst development requirements, and the impacts of an inline hot gas filter. A comparison with the fluidized bed system shows that there is potential for higher capital costs and lower catalyst costs in the fixed bed system, leading to comparable overall costs. The key catalyst requirement is to enable the effective transformation of highly oxygenated biomass into hydrocarbons products with properties suitable for blending into current fuels. Potential catalyst materials are discussed, along with their suitability for deoxygenation, hydrogenation and C–C coupling chemistry. This chemistry is necessary during pyrolysis vapor upgrading for improved bio-oil quality, which enables efficient downstream hydroprocessing; C–C coupling helps increase the proportion of diesel/jet fuel range product. One potential benefit of fixed bed upgrading over fluidized bed upgrading is catalyst flexibility, providing greater control over chemistry and product composition. Since this study is based on future projections, the impacts of uncertainties in the underlying assumptions are quantified via sensitivity analysis. As a result, this analysis indicates that catalyst researchers should prioritize by: carbon efficiency > catalyst cost > catalyst lifetime, after initially testing for basic operational feasibility.« less

Hairy root culture in a liquid-dispersed bioreactor: characterization of spatial heterogeneity.

PubMed

Williams, G R; Doran, P M

2000-01-01

A liquid-dispersed reactor equipped with a vertical mesh cylinder for inoculum support was developed for culture of Atropa belladonna hairy roots. The working volume of the culture vessel was 4.4 L with an aspect ratio of 1.7. Medium was dispersed as a spray onto the top of the root bed, and the roots grew radially outward from the central mesh cylinder to the vessel wall. Significant benefits in terms of liquid drainage and reduced interstitial liquid holdup were obtained using a vertical rather than horizontal support structure for the biomass and by operating the reactor with cocurrent air and liquid flow. With root growth, a pattern of spatial heterogeneity developed in the vessel. Higher local biomass densities, lower volumes of interstitial liquid, lower sugar concentrations, and higher root atropine contents were found in the upper sections of the root bed compared with the lower sections, suggesting a greater level of metabolic activity toward the top of the reactor. Although gas-liquid oxygen transfer to the spray droplets was very rapid, there was evidence of significant oxygen limitations in the reactor. Substantial volumes of non-free-draining interstitial liquid accumulated in the root bed. Roots near the bottom of the vessel trapped up to 3-4 times their own weight in liquid, thus eliminating the advantages of improved contact with the gas phase offered by liquid-dispersed culture systems. Local nutrient and product concentrations in the non-free-draining liquid were significantly different from those in the bulk medium, indicating poor liquid mixing within the root bed. Oxygen enrichment of the gas phase improved neither growth nor atropine production, highlighting the greater importance of liquid-solid compared with gas-liquid oxygen transfer resistance. The absence of mechanical or pneumatic agitation and the tendency of the root bed to accumulate liquid and impede drainage were identified as the major limitations to reactor performance. Improved reactor operating strategies and selection or development of root lines offering minimal resistance to liquid flow and low liquid retention characteristics are possible solutions to these problems.

Development of the Packed Bed Reactor ISS Flight Experiment

NASA Technical Reports Server (NTRS)

Patton, Martin O.; Bruzas, Anthony E.; Rame, Enrique; Motil, Brian J.

2012-01-01

Packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a leading candidate as a potential unit operation in support of long duration human space exploration. On earth, this type of reactor accounts for approximately 80% of all the reactors used in the chemical process industry today. Development of this technology for space exploration is truly crosscutting with many other potential applications (e.g., in-situ chemical processing of planetary materials and transport of nutrients through soil). NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. The first model developed by Motil et al., (2003) is based on a modified Ergun equation. This model was demonstrated at moderate gas and liquid flow rates, but extension to the lower flow rates expected in many advanced life support systems must be validated. The other model, developed by Guo et al., (2004) is based on Darcy s (1856) law for two-phase flow. This model has been validated for a narrow range of flow parameters indirectly (without full instrumentation) and included test points where the flow was not fully developed. The flight experiment presented will be designed with removable test sections to test the hydrodynamic models. The experiment will provide flexibility to test additional beds with different types of packing in the future. One initial test bed is based on the VRA (Volatile Removal Assembly), a packed bed reactor currently on ISS whose behavior in micro-gravity is not fully understood. Improving the performance of this system through an accurate model will increase our ability to purify water in the space environment.

Denitrification of groundwater using PHBV blends in packed bed reactors and the microbial diversity.

PubMed

Chu, Libing; Wang, Jianlong

2016-07-01

In the present study, three kinds of biopolymers, PHBV, PHBV/starch and PHBV/bamboo powder (BP) blends were used as carbon source and biofilm carriers for denitrification in packed bed reactors to remove nitrate from groundwater. Results showed that a fast start-up was obtained in bioreactors filled with both PHBV/Starch and PHBV/BP blends without external inocula and it took more than 3 month for PHBV reactor to reach the same loading rate. The PHBV/BP packed reactor exhibited a better nitrate removal efficiency (87.4 ± 7.0%) and less adverse effects in nitrite accumulation and DOC release (below 0.5 mg NO2N L(-1) and 10.5 mg DOC L(-1) in the effluent) during stable operation. Pyrosequencing analysis demonstrated that bacteria belonging to genus Clostridium in phylum Firmicus, which play the primary role in degrading the biopolymers, are the most dominant (33-15% of the sequences). The predominant species in all samples is related to Clostridium crotonatovorans. All the identified 11 genera of denitrifying bacteria affiliated with phylum Proteobacteria and constituted 30-55% in the representative sequences. The PHBV/BP blend is economically attractive carbon source with good denitrification performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Decolourization of remazol black-5 textile dyes using moving bed bio-film reactor

NASA Astrophysics Data System (ADS)

Pratiwi, R.; Notodarmojo, S.; Helmy, Q.

2018-01-01

The desizing and dyeing processes in the textile industries produces wastewaster containing high concentration of organic matter and colour, so it needs treatment before released to environment. In this research, removal of azo dye (Remazol Black 5/RB 5) and organic as COD was performed using Moving Bed Biofilm Reactor (MBBR). MBBR is biological treatment process with attached growth media system that can increase removal of organic matter in textile wastewater. The effectiveness of ozonation as pre-treatment process to increase the removal efficiency in MBBR was studied. The results showed that in MBBR batch system with detention time of 1 hour, pre-treatment with ozonation prior to MBBR process able to increase the colour removal efficiency of up to 86.74%. While on the reactor without ozone pre-treatment, the colour removal efficiency of up to 68.6% was achieved. From the continuous reactor experiments found that both colour and COD removal efficiency depends on time detention of RB-5 dyes in the system. The higher of detention time, the higher of colour and COD removal efficiency. It was found that optimum removal of colour and COD was achieved in 24 hour detention time with its efficiency of 96.9% and 89.13%, respectively.

A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed-bed microreactor

PubMed Central

Bogdan, Andrew

2009-01-01

Summary We demonstrate the preparation and characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leaving the organic product separate from the aqueous by-products. Furthermore, the microreactor oxidized a wide range of alcohols and remained active in excess of 100 trials without showing any loss of catalytic activity. PMID:19478910

Investigation of Multiphase Flow in a Packed Bed Reactor Under Microgravity Conditions

NASA Technical Reports Server (NTRS)

Lian, Yongsheng; Motil, Brian; Rame, Enrique

2016-01-01

In this paper we study the two-phase flow phenomena in a packed bed reactor using an integrated experimental and numerical method. The cylindrical bed is filled with uniformly sized spheres. In the experiment water and air are injected into the bed simultaneously. The pressure distribution along the bed will be measured. The numerical simulation is based on a two-phase flow solver which solves the Navier-Stokes equations on Cartesian grids. A novel coupled level set and moment of fluid method is used to construct the interface. A sequential method is used to position spheres in the cylinder. Preliminary experimental results showed that the tested flow rates resulted in pulse flow. The numerical simulation revealed that air bubbles could merge into larger bubbles and also could break up into smaller bubbles to pass through the pores in the bed. Preliminary results showed that flow passed through regions where the porosity is high. Comparison between the experimental and numerical results in terms of pressure distributions at different flow injection rates will be conducted. Comparison of flow phenomena under terrestrial gravity and microgravity will be made.

Pressurized pyrolysis of rice husk in an inert gas sweeping fixed-bed reactor with a focus on bio-oil deoxygenation.

PubMed

Qian, Yangyang; Zhang, Jie; Wang, Jie

2014-12-01

The pyrolysis of rice husk was conducted in a fixed-bed reactor with a sweeping nitrogen gas to investigate the effects of pressure on the pyrolytic behaviors. The release rates of main gases during the pyrolysis, the distributions of four products (char, bio-oil, water and gas), the elemental compositions of char, bio-oil and gas, and the typical compounds in bio-oil were determined. It was found that the elevation of pressure from 0.1MPa to 5.0MPa facilitated the dehydration and decarboxylation of bio-oil, and the bio-oils obtained under the elevated pressures had significantly less oxygen and higher calorific value than those obtained under atmospheric pressure. The former bio-oils embraced more acetic acid, phenols and guaiacols. The elevation of pressure increased the formation of CH4 partially via the gas-phase reactions. An attempt is made in this study to clarify "the pure pressure effect" and "the combined effect with residence time". Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of biochar activation by different methods on toxicity of soil contaminated by industrial activity.

PubMed

Kołtowski, Michał; Charmas, Barbara; Skubiszewska-Zięba, Jadwiga; Oleszczuk, Patryk

2017-02-01

The objective of the study was to determine the effect of various methods of biochar activation on the ecotoxicity of soils with various properties and with various content and origin of contaminants. The biochar produced from willow (at 700°C) was activated by 1) microwaves (in a microwave reactor under an atmosphere of water vapour), 2) carbon dioxide (in the quartz fluidized bed reactor) and 3) superheated steam (in the quartz fluidized bed reactor). Three different soils were collected from industrial areas. The soils were mixed with biochar and activated biochars at the dose of 5% and ecotoxicological parameters of mixture was evaluated using two solid phase test - Phytotoxkit F (Lepidium sativum) and Collembolan test (Folsomia candida) and one liquid phase test - Microtox® (Vibrio fischeri). Biochar activation had both positive and negative impacts, depending on the activation method, kind of bioassay and kind of soil. Generally, biochar activated by microwaves increased the effectiveness of ecotoxicity reduction relative to non-activated biochars. Whereas, biochar activated with CO 2 most often cause a negative effect manifested by deterioration or as a lack of improvement in relation to non-activated biochar or to non-amended soil. It was also demonstrated that the increase of biochar specific surface area caused a significant reduction of toxicity of water leachates from the studied soils. Effectiveness of the reduction of leachate toxicity was weakened in the presence of dissolved organic carbon in the soil. Copyright © 2016 Elsevier Inc. All rights reserved.

Apparatus, components and operating methods for circulating fluidized bed transport gasifiers and reactors

DOEpatents

Vimalchand, Pannalal; Liu, Guohai; Peng, Wan Wang

2015-02-24

The improvements proposed in this invention provide a reliable apparatus and method to gasify low rank coals in a class of pressurized circulating fluidized bed reactors termed "transport gasifier." The embodiments overcome a number of operability and reliability problems with existing gasifiers. The systems and methods address issues related to distribution of gasification agent without the use of internals, management of heat release to avoid any agglomeration and clinker formation, specific design of bends to withstand the highly erosive environment due to high solid particles circulation rates, design of a standpipe cyclone to withstand high temperature gasification environment, compact design of seal-leg that can handle high mass solids flux, design of nozzles that eliminate plugging, uniform aeration of large diameter Standpipe, oxidant injection at the cyclone exits to effectively modulate gasifier exit temperature and reduction in overall height of the gasifier with a modified non-mechanical valve.

Corn stalks char from fast pyrolysis as precursor material for preparation of activated carbon in fluidized bed reactor.

PubMed

Wang, Zhiqi; Wu, Jingli; He, Tao; Wu, Jinhu

2014-09-01

Corn stalks char from fast pyrolysis was activated by physical and chemical activation process in a fluidized bed reactor. The structure and morphology of the carbons were characterized by N2 adsorption and SEM. Effects of activation time and activation agents on the structure of activation carbon were investigated. The physically activated carbons with CO2 have BET specific surface area up to 880 m(2)/g, and exhibit microporous structure. The chemically activated carbons with H3PO4 have BET specific surface area up to 600 m(2)/g, and exhibit mesoporous structure. The surface morphology shows that physically activated carbons exhibit fibrous like structure in nature with long ridges, resembling parallel lines. Whereas chemically activated carbons have cross-interconnected smooth open pores without the fibrous like structure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect on the tritium breeding ratio for a distributed ICRF antenna in a DEMO reactor

NASA Astrophysics Data System (ADS)

Garcia, A.; Noterdaeme, J.-M.; Fischer, U.; Dies, J.

2015-12-01

The paper reports results of MCNP-5 calculations to assess the effect on the Tritium Breeding Ratio (TBR) when integrating a distributed Ion Cyclotron Range of Frequencies (ICRF) antenna in the blanket of DEMO fusion power reactor. The calculations consider different parameters such as the ICRF covering ratio and the type of breeding blanket including the Helium Cooled Pebble Bed (HCPB) and the Helium Cooled Lithium Lead (HCLL) concepts. For an antenna with a full toroidal circumference of 360°, located poloidally at 40° with a poloidal extension of 1 m, the reduction of the TBR is -0.349% for the HCPB blanket and -0.532% for the HCLL blanket. The distributed ICRF antenna is thus shown to have only a marginal effect on the TBR of the DEMO reactor.

Modeling the impact of bubbling bed hydrodynamics on tar yield and its fluctuations during biomass fast pyrolysis

DOE PAGES

Xiong, Qingang; Ramirez, Emilio; Pannala, Sreekanth; ...

2015-10-09

The impact of bubbling bed hydrodynamics on temporal variations in the exit tar yield for biomass fast pyrolysis was investigated using computational simulations of an experimental laboratory-scale reactor. A multi-fluid computational fluid dynamics model was employed to simulate the differential conservation equations in the reactor, and this was combined with a multi-component, multi-step pyrolysis kinetics scheme for biomass to account for chemical reactions. The predicted mean tar yields at the reactor exit appear to match corresponding experimental observations. Parametric studies predicted that increasing the fluidization velocity should improve the mean tar yield but increase its temporal variations. Increases in themore » mean tar yield coincide with reducing the diameter of sand particles or increasing the initial sand bed height. However, trends in tar yield variability are more complex than the trends in mean yield. The standard deviation in tar yield reaches a maximum with changes in sand particle size. As a result, the standard deviation in tar yield increases with the increases in initial bed height in freely bubbling state, while reaches a maximum in slugging state.« less

Effects of biofilm on flow over and through a permeable bed

NASA Astrophysics Data System (ADS)

Kazemifar, Farzan; Blois, Gianluca; Aybar, Marcelo; Perez-Calleja, Patricia; Nerenberg, Robert; Sinha, Sumit; Hardy, Richard; Best, James; Sambrook-Smith, Gregory; Christensen, Kenneth

2016-11-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the interface of fluids and solids, such as riverbeds. Biofilms are permeable, heterogeneous, and deformable structures that can influence the flow and mass/momentum transport, yet their interaction with flow is not fully understood in part due to technical obstacles impeding quantitative experimental investigations. The porosity of river beds results in the generation of a diverse mosaic of 'suction' and 'ejection' events that are far removed from typical assumptions of turbulent flow structure over an impermeable bed. In this work, the effect of biofilm on bed permeability is studied. Experiments are conducted in a closed water channel equipped with 4-cm-deep permeable bed models consisting of horizontal cylinders normal to the bulk flow direction, forming an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent biofilm reactor to initiate and control the biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

Effects of biofilm on flow over and through a permeable bed

NASA Astrophysics Data System (ADS)

Kazemifar, F.; Blois, G.; Aybar, M.; Perez Calleja, P.; Nerenberg, R.; Sinha, S.; Hardy, R. J.; Best, J.; Sambrook Smith, G.; Christensen, K. T.

2016-12-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces, such as riverbeds. Biofilms are permeable, heterogeneous, and deformable structures that can influence the flow and mass/momentum transport, yet their interaction with flow is not fully understood in part due to technical obstacles impeding quantitative experimental investigations. The porosity of river beds results in the generation of a diverse mosaic of `suction' and `ejection' events that are far removed from typical assumptions of turbulent flow structure over an impermeable bed. In this work, the effect of biofilm on bed permeability is studied. Experiments are conducted in a closed water channel equipped with 4-cm-deep permeable bed models consisting of horizontal cylinders normal to the bulk flow direction, forming an idealized two-dimensional permeable bed (Figure 1). Prior to conducting flow experiments, the models are placed within an independent biofilm reactor to initiate and accurately control the biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

Fluidized bed combustor and tube construction therefor

DOEpatents

De Feo, Angelo; Hosek, William

1981-01-01

A fluidized bed combustor comprises a reactor or a housing which has a windbox distributor plate adjacent the lower end thereof which contains a multiplicity of hole and air discharge nozzles for discharging air and coal into a fluidized bed which is maintained above the distributor plate and below a take-off connection or flue to a cyclone separator in which some of the products of combustion are treated to remove the dust which is returned into the fluidized bed. A windbox is spaced below the fluidized bed and it has a plurality of tubes passing therethrough with the passage of combustion air and fluidizing air which passes through an air space so that fluidizing air is discharged into the reaction chamber fluidized bed at the bottom thereof to maintain the bed in a fluidized condition. A fluid, such as air, is passed through the tubes which extend through the windbox and provide a preheating of the combustion air and into an annular space between telescoped inner and outer tubes which comprise heat exchanger tubes or cooling tubes which extend upwardly through the distributor plate into the fluidized bed. The heat exchanger tubes are advantageously arranged so that they may be exposed in groups within the reactor in a cluster which is arranged within holding rings.

Tube construction for fluidized bed combustor

DOEpatents

De Feo, Angelo; Hosek, William

1984-01-01

A fluidized bed combustor comprises a reactor or a housing which has a windbox distributor plate adjacent the lower end thereof which contains a multiplicity of hole and air discharge nozzles for discharging air and coal into a fluidized bed which is maintained above the distributor plate and below a take-off connection or flue to a cyclone separator in which some of the products of combustion are treated to remove the dust which is returned into the fluidized bed. A windbox is spaced below the fluidized bed and it has a plurality of tubes passing therethrough with the passage of combustion air and fluidizing air which passes through an air space so that fluidizing air is discharged into the reaction chamber fluidized bed at the bottom thereof to maintain the bed in a fluidized condition. A fluid, such as air, is passed through the tubes which extend through the windbox and provide a preheating of the combustion air and into an annular space between telescoped inner and outer tubes which comprise heat exchanger tubes or cooling tubes which extend upwardly through the distributor plate into the fluidized bed. The heat exchanger tubes are advantageously arranged so that they may be exposed in groups within the reactor in a cluster which is arranged within holding rings.

Fluidized bed coal combustion reactor

NASA Technical Reports Server (NTRS)

Moynihan, P. I.; Young, D. L. (Inventor)

1981-01-01

A fluidized bed coal reactor includes a combination nozzle-injector ash-removal unit formed by a grid of closely spaced open channels, each containing a worm screw conveyor, which function as continuous ash removal troughs. A pressurized air-coal mixture is introduced below the unit and is injected through the elongated nozzles formed by the spaces between the channels. The ash build-up in the troughs protects the worm screw conveyors as does the cooling action of the injected mixture. The ash layer and the pressure from the injectors support a fluidized flame combustion zone above the grid which heats water in boiler tubes disposed within and/or above the combustion zone and/or within the walls of the reactor.

Modeling and simulation of an enzymatic reactor for hydrolysis of palm oil.

PubMed

Bhatia, S; Naidu, A D; Kamaruddin, A H

1999-01-01

Hydrolysis of palm oil has become an important process in Oleochemical industries. Therefore, an investigation was carried out for hydrolysis of palm oil to fatty acid and glycerol using immobilized lipase in packed bed reactor. The conversion vs. residence time data were used in Michaelis-Menten rate equation to evaluate the kinetic parameters. A mathematical model for the rate of palm oil hydrolysis was proposed incorporating role of external mass transfer and pore diffusion. The model was simulated for steady-state isothermal operation of immobilized lipase packed bed reactor. The experimental data were compared with the simulated results. External mass transfer was found to affect the rate of palm oil hydrolysis at higher residence time.

Effect of Superficial Gas Velocity on the Solid Temperature Distribution in Gas Fluidized Beds with Heat Production

PubMed Central

2017-01-01

The hydrodynamics and heat transfer of cylindrical gas–solid fluidized beds for polyolefin production was investigated with the two-fluid model (TFM) based on the kinetic theory of granular flow (KTGF). It was found that the fluidized bed becomes more isothermal with increasing superficial gas velocity. This is mainly due to the increase of solids circulation and improvement in gas solid contact. It was also found that the average Nusselt number weakly depends on the gas velocity. The TFM results were qualitatively compared with simulation results of computational fluid dynamics combined with the discrete element model (CFD-DEM). The TFM results were in very good agreement with the CFD-DEM outcomes, so the TFM can be a reliable source for further investigations of fluidized beds especially large lab-scale reactors PMID:29187774

Treatment of mountain refuge wastewater by fixed and moving bed biofilm systems.

PubMed

Andreottola, G; Damiani, E; Foladori, P; Nardelli, P; Ragazzi, M

2003-01-01

Tourists visiting mountain refuges in the Alps have increased significantly in the last decade and the number of refuges and huts at high altitude too. In this research the results of an intensive monitoring of a wastewater treatment plant (WWTP) for a tourist mountain refuge located at 2,981 m a.s.l. are described. Two biofilm reactors were adopted: (a) a Moving Bed Biofilm Reactor (MBBR); (b) a submerged Fixed Bed Biofilm Reactor (FBBR). The aims of this research were: (i) the evaluation of the main parameters characterising the processes and involved in the design of the wastewater plants, in order to compare advantages and disadvantages of the two tested alternatives; (ii) the acquisition of an adequate knowledge of the problems connected with the wastewater treatment in alpine refuges. The main results have been: (i) a quick start-up of the biological reactors obtainable thanks to a pre-colonization before the transportation of the plastic carriers to the refuge at the beginning of the tourist season; (ii) low volume and area requirement; (iii) significantly higher removal efficiency compared to other fixed biomass systems, such as trickling filters, but the energy consumption is higher.

BENCH-SCALE EVALUATION OF CALCIUM SORBENTS FOR ACID GAS EMISSION CONTROL

EPA Science Inventory

Calcium sorbents for acid gas emission control were evaluated for effectiveness in removing SO2/HCl and SO2/NO from simulated incinerator and boiler flue gases. All tests were conducted in a bench-scale reactor (fixed-bed) simulating fabric filter conditions in an acid gas remova...

THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

EPA Science Inventory

Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

Biofilm development during the start-up of a sulfate-reducing down-flow fluidized bed reactor at different COD/SO4(2-) ratios and HRT.

PubMed

Piña-Salazar, E Z; Cervantes, F J; Meraz, M; Celis, L B

2011-01-01

In sulfate-reducing reactors, it has been reported that the sulfate removal efficiency increases when the COD/SO4(2-) ratio is increased. The start-up of a down-flow fluidized bed reactor constitutes an important step to establish a microbial community in the biofilm able to survive under the operational bioreactor conditions in order to achieve effective removal of both sulfate and organic matter. In this work the influence of COD/SO4(2-) ratio and HRT in the development of a biofilm during reactor start-up (35 days) was studied. The reactor was inoculated with 1.6 g VSS/L of granular sludge, ground low density polyethylene was used as support material; the feed consisted of mineral medium at pH 5.5 containing 1 g COD/L (acetate:lactate, 70:30) and sodium sulfate. Four experiments were conducted at HRT of 1 or 2 days and COD/SO4(2-) ratio of 0.67 or 2.5. The results obtained indicated that a COD/SO4(2-) ratio of 2.5 and HRT 2 days allowed high sulfate and COD removal (66.1 and 69.8%, respectively), whereas maximum amount of attached biomass (1.9 g SVI/L support) and highest sulfate reducing biofilm activity (10.1 g COD-H2S/g VSS-d) was achieved at HRT of 1 day and at COD/sulfate ratios of 0.67 and 2.5, respectively, which suggests that suspended biomass also played a key role in the performance of the reactors.

Effective Thermal Property Estimation of Unitary Pebble Beds Based on a CFD-DEM Coupled Method for a Fusion Blanket

NASA Astrophysics Data System (ADS)

Chen, Lei; Chen, Youhua; Huang, Kai; Liu, Songlin

2015-12-01

Lithium ceramic pebble beds have been considered in the solid blanket design for fusion reactors. To characterize the fusion solid blanket thermal performance, studies of the effective thermal properties, i.e. the effective thermal conductivity and heat transfer coefficient, of the pebble beds are necessary. In this paper, a 3D computational fluid dynamics discrete element method (CFD-DEM) coupled numerical model was proposed to simulate heat transfer and thereby estimate the effective thermal properties. The DEM was applied to produce a geometric topology of a prototypical blanket pebble bed by directly simulating the contact state of each individual particle using basic interaction laws. Based on this geometric topology, a CFD model was built to analyze the temperature distribution and obtain the effective thermal properties. The current numerical model was shown to be in good agreement with the existing experimental data for effective thermal conductivity available in the literature. supported by National Special Project for Magnetic Confined Nuclear Fusion Energy of China (Nos. 2013GB108004, 2015GB108002, 2014GB122000 and 2014GB119000), and National Natural Science Foundation of China (No. 11175207)

High performance biological methanation in a thermophilic anaerobic trickle bed reactor.

PubMed

Strübing, Dietmar; Huber, Bettina; Lebuhn, Michael; Drewes, Jörg E; Koch, Konrad

2017-12-01

In order to enhance energy efficiency of biological methanation of CO 2 and H 2 , this study investigated the performance of a thermophilic (55°C) anaerobic trickle bed reactor (ATBR) (58.1L) at ambient pressure. With a methane production rate of up to 15.4m 3 CH4 /(m 3 trickle bed ·d) at methane concentrations above 98%, the ATBR can easily compete with the performance of other mixed culture methanation reactors. Control of pH and nutrient supply turned out to be crucial for stable operation and was affected significantly by dilution due to metabolic water production, especially during demand-orientated operation. Considering practical applications, inoculation with digested sludge, containing a diverse biocenosis, showed high adaptive capacity due to intrinsic biological diversity. However, no macroscopic biofilm formation was observed at thermophilic conditions even after 313days of operation. The applied approach illustrates the high potential of thermophilic ATBRs as a very efficient energy conversion and storage technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Immobilized glucose oxidase--catalase and their deactivation in a differential-bed loop reactor.

PubMed

Prenosil, J E

1979-01-01

Glucose oxidase containing catalase was immobilized with a copolymer of phenylenediamine and glutaraldehyde on pumice and titania carrier to study the enzymatic oxidation of glucose in a differential-bed loop reactor. The reaction rate was found to be first order with respect to the concentration of limiting oxygen substrate, suggesting a strong external mass-transfer resistance for all the flow rates used. The partial pressure of oxygen was varied from 21.3 up to 202.6 kPa. The use of a differential-bed loop reactor for the determination of the active enzyme concentration in the catalyst with negligible internal pore diffusion resistance is shown. Catalyst deactivation was studied, especially with respect to the presence of catalase. It is believed that the hydrogen peroxide formed in the oxidation reaction deactivates catalase first; if an excess of catalase is present, the deactivation of glucose oxidase remains small. The mathematical model subsequently developed adequately describes the experimental results.

Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR) studies.

PubMed

Vadgama, Rajeshkumar N; Odaneth, Annamma A; Lali, Arvind M

2015-12-01

Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.

Method and apparatus for incinerating hazardous waste

DOEpatents

Korenberg, Jacob

1990-01-01

An incineration apparatus and method for disposal of infectious hazardous waste including a fluidized bed reactor containing a bed of granular material. The reactor includes a first chamber, a second chamber, and a vertical partition separating the first and second chambers. A pressurized stream of air is supplied to the reactor at a sufficient velocity to fluidize the granular material in both the first and second chambers. Waste materials to be incinerated are fed into the first chamber of the fluidized bed, the fine waste materials being initially incinerated in the first chamber and subsequently circulated over the partition to the second chamber wherein further incineration occurs. Coarse waste materials are removed from the first chamber, comminuted, and recirculated to the second chamber for further incineration. Any partially incinerated waste materials and ash from the bottom of the second chamber are removed and recirculated to the second chamber for further incineration. This process is repeated until all infectious hazardous waste has been completely incinerated.

Multiscale Evaluation of Catalytic Upgrading of Biomass Pyrolysis Vapors on Ni- and Ga-Modified ZSM-5

DOE PAGES

Yung, Matthew M.; Stanton, Alexander R.; Iisa, Kristiina; ...

2016-10-07

Metal-impregnated (Ni or Ga) ZSM-5 catalysts were studied for biomass pyrolysis vapor upgrading to produce hydrocarbons using three reactors constituting a 100 000x change in the amount of catalyst used in experiments. Catalysts were screened for pyrolysis vapor phase upgrading activity in two small-scale reactors: (i) a Pyroprobe with a 10 mg catalyst in a fixed bed and (ii) a fixed-bed reactor with 500 mg of catalyst. The best performing catalysts were then validated with a larger scale fluidized-bed reactor (using ~1 kg of catalyst) that produced measurable quantities of bio-oil for analysis and evaluation of mass balances. Despite somemore » inherent differences across the reactor systems (such as residence time, reactor type, analytical techniques, mode of catalyst and biomass feed) there was good agreement of reaction results for production of aromatic hydrocarbons, light gases, and coke deposition. Relative to ZSM-5, Ni or Ga addition to ZSM-5 increased production of fully deoxygenated aromatic hydrocarbons and light gases. In the fluidized bed reactor, Ga/ZSM-5 slightly enhanced carbon efficiency to condensed oil, which includes oxygenates in addition to aromatic hydrocarbons, and reduced oil oxygen content compared to ZSM-5. Ni/ZSM-5, while giving the highest yield of fully deoxygenated aromatic hydrocarbons, gave lower overall carbon efficiency to oil but with the lowest oxygen content. Reaction product analysis coupled with fresh and spent catalyst characterization indicated that the improved performance of Ni/ZSM-5 is related to decreasing deactivation by coking, which keeps the active acid sites accessible for the deoxygenation and aromatization reactions that produce fully deoxygenated aromatic hydrocarbons. The addition of Ga enhances the dehydrogenation activity of the catalyst, which leads to enhanced olefin formation and higher fully deoxygenated aromatic hydrocarbon yields compared to unmodified ZSM-5. Catalyst characterization by ammonia temperature programmed desorption, surface area measurements, and postreaction temperature-programmed oxidation (TPO) also showed that the metal-modified zeolites retained a greater percentage of their initial acidity and surface area, which was consistent between the reactor scales. These results demonstrate that the trends observed with smaller (milligram to gram) catalyst reactors are applicable to larger, more industrially relevant (kg) scales to help guide catalyst research toward application.« less

Catalyst and process development for synthesis gas conversion to isobutylene. Final report, September 1, 1990--January 31, 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anthony, R.G.; Akgerman, A.

1994-05-06

Previous work on isosynthesis (conversion of synthesis gas to isobutane and isobutylene) was performed at very low conversions or extreme process conditions. The objectives of this research were (1) determine the optimum process conditions for isosynthesis; (2) determine the optimum catalyst preparation method and catalyst composition/properties for isosynthesis; (3) determine the kinetics for the best catalyst; (4) develop reactor models for trickle bed, slurry, and fixed bed reactors; and (5) simulate the performance of fixed bed trickle flow reactors, slurry flow reactors, and fixed bed gas phase reactors for isosynthesis. More improvement in catalyst activity and selectivity is needed beforemore » isosynthesis can become a commercially feasible (stand-alone) process. Catalysts prepared by the precipitation method show the most promise for future development as compared with those prepared hydrothermally, by calcining zirconyl nitrate, or by a modified sol-gel method. For current catalysts the high temperatures (>673 K) required for activity also cause the production of methane (because of thermodynamics). A catalyst with higher activity at lower temperatures would magnify the unique selectivity of zirconia for isobutylene. Perhaps with a more active catalyst and acidification, oxygenate production could be limited at lower temperatures. Pressures above 50 atm cause an undesirable shift in product distribution toward heavier hydrocarbons. A model was developed that can predict carbon monoxide conversion an product distribution. The rate equation for carbon monoxide conversion contains only a rate constant and an adsorption equilibrium constant. The product distribution was predicted using a simple ratio of the rate of CO conversion. This report is divided into Introduction, Experimental, and Results and Discussion sections.« less

Prevention of clogging in a biological trickle-bed reactor removing toluene from contaminated air.

PubMed

Weber, F J; Hartmans, S

1996-04-05

Removal of organic compounds like toluene from waste gases with a trickle-bed reactor can result in clogging of the reactor due to the formation of an excessive amount of biomass. We therefore limited the amount of nutrients available for growth, to prevent clogging of the reactor. As a consequence of this nutrient limitation a lower removal rate was observed. However, when a fungal culture was used to inoculate the reactor, the toluene removal rate under nutrient limiting conditions was higher. Over a period of 375 days, an average removal rate of 27 g C/(m(3) h) was obtained with the reactor inoculated with the fungal culture. From the carbon balance over the reactor and the nitrogen availability it was concluded that, under these nutrient-limited conditions, large amounts of carbohydrates are probably formed. We also studied the application of a NaOH wash to remove excess biomass, as a method to prevent clogging. Under these conditions an average toluene removal rate of 35 g C/(m(3) h) was obtained. After about 50 days there was no net increase in the biomass content of the reactor. The amount of biomass which was formed in the reactor equaled the amount removed by the NaOH wash.

Effect of acidity and elevated PCO2 on acid. Neutralization within pulsed limestone bed reactors receiving coal mine drainage

USGS Publications Warehouse

Watten, B.J.; Sibrell, P.L.; Schwartz, M.F.

2004-01-01

Limestone has potential for reducing reagent costs and sludge volume associated with the treatment of acid mine drainage (AMD), but its use has been restricted by slow dissolution rates and sensitivity to scale forming reactions that retard transport of H+ at the solid-liquid interface. We evaluated a pulsed limestone bed (PLB) remediation process designed to circumvent these problems through use of intermittently fluidized beds of granular limestone and elevated carbon dioxide pressure. PLB limestone dissolution (LD, mg/L), and effluent alkalinity (Alk, mg/L) were correlated with reactor pressure (PCO2, kPa), influent acidity (Acy, mg/L) and reactor bed height (H, cm) using a prototype capable of processing 10 L/min. The PLB process effectively neutralized sulfuric acid acidity over the range of 6-1033 mg/L (as CaCO3) while generating high concentrations of alkalinity (36-1086 mg/L) despite a hydraulic residence time of just 4.2-5.0 min. Alk and LD (mg/L CaCO3) rose with increases in influent acidity and PCO2 (p < 0.001) according to the models: Alk = 58 + 38.4 (PCO2)0.5 + 0.080 (Acy) - 0.0059(PCO2) 0.5 (Acy); LD = 55 + 38.3 (PCO2)0.5 + 1.08 (Acy) - 0.0059 (PCO2)0.5 (Acy). Alkalinity decreased at an increasing rate with reductions in H over the range of 27.3-77.5 cm (p < 0.001). Carbon dioxide requirements (Q(avg)CO2, L/min) increased with PCO2 (p < 0.001) following the model Q(avg)CO2 = 0.858 (PCO2)0.620, resulting in a greater degree of pH buffering (depression) within the reactors, a rise in limestone solubility and an increase in limestone dissolution related to carbonic acid attack. Corresponding elevated concentrations of effluent alkalinity allow for sidestream treatment with blending. Numerical modeling demonstrated that carbon dioxide requirements are reduced as influent acidity rises and when carbon dioxide is recovered from system effluent and recycled. Field trials demonstrated that the PLB process is capable of raising the pH of AMD above that required for hydrolysis and precipitation of Fe3+ and Al 3+ but not Fe2+ and Mn2+.

Design and performance of a trickle-bed bioreactor with immobilized hybridoma cells.

PubMed

Phillips, H A; Scharer, J M; Bols, N C; Moo-Young, M

1992-01-01

A trickle-bed system employing inert matrices of vermiculite or polyurethane foam packed in the downcomer section of a split-flow air-lift reactor has been developed for hybridoma culture to enhance antibody productivity. This quiescent condition favoured occlusion and allowed the cells to achieve densities twelve fold greater (12.8 x 10(6) cells/ml reactor for polyurethane foam) than in free cell suspension. The reactor was operated in a cyclic batch mode whereby defined volumes of medium were periodically withdrawn and replaced with equal volumes of fresh medium. The pH of the medium was used as the indicator of the feeding schedule. Glucose, lactate and ammonia concentrations reached a stationary value after 5 days. With vermiculite packing, a monoclonal antibody (MAb) concentration of 2.4 mg/l was achieved after 12 days. The MAb concentration declined then increased to a value of 1.8 mg/l. In the polyurethane foam average monoclonal antibody (MAb) concentrations reached a stationary value of 1.1 mg/l in the first 20 days and increased to a new stationary state value of 2.1 mg/l for the remainder of the production. MAb productivity in the trickle-bed reactor was 0.3 mg/l.d (polyurethane foam) and 0.18 mg/l.d (vermiculite) in comparison to 0.12 mg/l.d for free cell suspension. This trickle-bed system seems to be an attractive way of increasing MAb productivity in culture.

Reactor for in situ measurements of spatially resolved kinetic data in heterogeneous catalysis

NASA Astrophysics Data System (ADS)

Horn, R.; Korup, O.; Geske, M.; Zavyalova, U.; Oprea, I.; Schlögl, R.

2010-06-01

The present work describes a reactor that allows in situ measurements of spatially resolved kinetic data in heterogeneous catalysis. The reactor design allows measurements up to temperatures of 1300 °C and 45 bar pressure, i.e., conditions of industrial relevance. The reactor involves reactants flowing through a solid catalyst bed containing a sampling capillary with a side sampling orifice through which a small fraction of the reacting fluid (gas or liquid) is transferred into an analytical device (e.g., mass spectrometer, gas chromatograph, high pressure liquid chromatograph) for quantitative analysis. The sampling capillary can be moved with μm resolution in or against flow direction to measure species profiles through the catalyst bed. Rotation of the sampling capillary allows averaging over several scan lines. The position of the sampling orifice is such that the capillary channel through the catalyst bed remains always occupied by the capillary preventing flow disturbance and fluid bypassing. The second function of the sampling capillary is to provide a well which can accommodate temperature probes such as a thermocouple or a pyrometer fiber. If a thermocouple is inserted in the sampling capillary and aligned with the sampling orifice fluid temperature profiles can be measured. A pyrometer fiber can be used to measure the temperature profile of the solid catalyst bed. Spatial profile measurements are demonstrated for methane oxidation on Pt and methane oxidative coupling on Li/MgO, both catalysts supported on reticulated α -Al2O3 foam supports.

High efficiency chlorine removal from polyvinyl chloride (PVC) pyrolysis with a gas-liquid fluidized bed reactor.

PubMed

Yuan, G; Chen, D; Yin, L; Wang, Z; Zhao, L; Wang, J Y

2014-06-01

In this research a gas-liquid fluidized bed reactor was developed for removing chlorine (Cl) from polyvinyl chloride (PVC) to favor its pyrolysis treatment. In order to efficiently remove Cl within a limited time before extensive generation of hydrocarbon products, the gas-liquid fluidized bed reactor was running at 280-320 °C, where hot N2 was used as fluidizing gas to fluidize the molten polymer, letting the molten polymer contact well with N2 to release Cl in form of HCl. Experimental results showed that dechlorination efficiency is mainly temperature dependent and 300 °C is a proper reaction temperature for efficient dechlorination within a limited time duration and for prevention of extensive pyrolysis; under this temperature 99.5% of Cl removal efficiency can be obtained within reaction time around 1 min after melting is completed as the flow rate of N2 gas was set around 0.47-0.85 Nm(3) kg(-1) for the molten PVC. Larger N2 flow rate and additives in PVC would enhance HCl release but did not change the final dechlorination efficiency; and excessive N2 flow rate should be avoided for prevention of polymer entrainment. HCl is emitted from PVC granules or scraps at the mean time they started to melt and the melting stage should be taken into consideration when design the gas-liquid fluidized bed reactor for dechlorination. Copyright © 2013 Elsevier Ltd. All rights reserved.

Wastewater treatment using a novel bioreactor with submerged packing bed of polyethylene tape.

PubMed

Mijaylova Nacheva, P; Moeller Chávez, G

2010-01-01

The performance of a novel aerobic bioreactor with a specially designed submerged packing bed of high specific surface area density, made of polyethylene tape, was studied for the treatment of domestic wastewater. The reactor has a volume of 0.71 m(3) and the specific area of the packing bed was 1,098 m(2)/m(3). The operation was performed with and without effluent recycling, applying different organic loads in the range of 4.0-17.6 g COD m(-2) d(-1). No back-washings were carried out. Overall BOD(5) removals of 90-95% were obtained with organic loads of 4.0-17.6 g COD m(-2) d(-1) and HRT of 0.2-1.1 h. Overall TN removal of 69-72% was obtained at loads of 0.8-4.6 g TN m(-2) d(-1) when effluent recycling was used. The reactor allowed obtaining high quality water for urban reuse and demonstrated an effective process performance and resistance to load variations. The developed biofilm was completely penetrated by the organic matter, ammonia and oxygen, providing high removal rates. Large biomass quantities, up to 13 g dry VS/m(2), were reached in the reactor and the determined sludge yield coefficient was relatively low, of 0.25 g VSS/g COD. These results allow obtaining compact treatment systems with low sludge production and make the technology a suitable option for small wastewater treatment plants.

A One-group, One-dimensional Transport Benchmark in Cylindrical Geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barry Ganapol; Abderrafi M. Ougouag

A 1-D, 1-group computational benchmark in cylndrical geometry is described. This neutron transport benchmark is useful for evaluating reactor concepts that possess azimuthal symmetry such as a pebble-bed reactor.

Achieving nitritation in a continuous moving bed biofilm reactor at different temperatures through ratio control.

PubMed

Bian, Wei; Zhang, Shuyan; Zhang, Yanzhuo; Li, Wenjing; Kan, Ruizhe; Wang, Wenxiao; Zheng, Zhaoming; Li, Jun

2017-02-01

A ratio control strategy was implemented in a continuous moving bed biofilm reactor (MBBR) to investigate the response to different temperatures. The control strategy was designed to maintain a constant ratio between dissolved oxygen (DO) and total ammonia nitrogen (TAN) concentrations. The results revealed that a stable nitritation in a biofilm reactor could be achieved via ratio control, which compensated the negative influence of low temperatures by stronger oxygen-limiting conditions. Even with a temperature as low as 6°C, stable nitritation could be achieved when the controlling ratio did not exceed 0.17. Oxygen-limiting conditions in the biofilm reactor were determined by the DO/TAN concentrations ratio, instead of the mere DO concentration. This ratio control strategy allowed the achievement of stable nitritation without complete wash-out of NOB from the reactor. Through the ratio control strategy full nitritation of sidestream wastewater was allowed; however, for mainstream wastewater, only partial nitritation was recommended. Copyright © 2016 Elsevier Ltd. All rights reserved.

Integrated reformer and shift reactor

DOEpatents

Bentley, Jeffrey M.; Clawson, Lawrence G.; Mitchell, William L.; Dorson, Matthew H.

2006-06-27

A hydrocarbon fuel reformer for producing diatomic hydrogen gas is disclosed. The reformer includes a first reaction vessel, a shift reactor vessel annularly disposed about the first reaction vessel, including a first shift reactor zone, and a first helical tube disposed within the first shift reactor zone having an inlet end communicating with a water supply source. The water supply source is preferably adapted to supply liquid-phase water to the first helical tube at flow conditions sufficient to ensure discharge of liquid-phase and steam-phase water from an outlet end of the first helical tube. The reformer may further include a first catalyst bed disposed in the first shift reactor zone, having a low-temperature shift catalyst in contact with the first helical tube. The catalyst bed includes a plurality of coil sections disposed in coaxial relation to other coil sections and to the central longitudinal axis of the reformer, each coil section extending between the first and second ends, and each coil section being in direct fluid communication with at least one other coil section.

Removal of hazardous gaseous pollutants from industrial flue gases by a novel multi-stage fluidized bed desulfurizer.

PubMed

Mohanty, C R; Adapala, Sivaji; Meikap, B C

2009-06-15

Sulfur dioxide and other sulfur compounds are generated as primary pollutants from the major industries such as sulfuric acid plants, cupper smelters, catalytic cracking units, etc. and cause acid rain. To remove the SO(2) from waste flue gas a three-stage counter-current multi-stage fluidized bed adsorber was developed as desulfurization equipment and operated in continuous bubbling fluidization regime for the two-phase system. This paper represents the desulfurization of gas mixtures by chemical sorption of sulfur dioxide on porous granular calcium oxide particles in the reactor at ambient temperature. The advantages of the multi-stage fluidized bed reactor are of high mass transfer and high gas-solid residence time that can enhance the removal of acid gas at low temperature by dry method. Experiments were carried out in the bubbling fluidization regime supported by visual observation. The effects of the operating parameters such as sorbent (lime) flow rate, superficial gas velocity, and the weir height on SO(2) removal efficiency in the multistage fluidized bed are reported. The results have indicated that the removal efficiency of the sulfur dioxide was found to be 65% at high solid flow rate (2.0 kg/h) corresponding to lower gas velocity (0.265 m/s), wier height of 70 mm and SO(2) concentration of 500 ppm at room temperature.

Evaluation of Municipal Wastewater Treatment Plant Activated Sludge for Biodegradation of Propylene Glycol as an Aircraft Deicing Fluid

DTIC Science & Technology

2012-03-01

Propylene Glycol Deicer Biodegredation Kinetics: Complete-Mix Stirred Tank Reactors , Filter, and Fluidized Bed . Journal of Environmental...scale sequencing batch reactor containing municipal waste water treatment facility activated sludge (AS) performing simultaneous organic carbon...Sequencing Batch Reactor Operation ..................................................................... 13 PG extraction from AS

A Hydrodynamic Characteristic of a Dual Fluidized Bed Gasification

NASA Astrophysics Data System (ADS)

Sung, Yeon Kyung; Song, Jae Hun; Bang, Byung Ryeul; Yu, Tae U.; Lee, Uen Do

A cold model dual fluidized bed (DFB) reactor, consisting of two parallel interconnected bubbling and fast fluidized beds, was designed for developing an auto-thermal biomass gasifier. The combustor of this system burns the rest char of the gasification process and provides heat to the gasifier by circulating solids inventory. To find an optimal mixing and circulation of heavy solid inventory and light biomass and char materials, we investigate two types of DFB reactors which have different configuration of distributor and way-out location of the solid inventory and char materials in the gasifier. To determine appropriate operating conditions, we measured minimum fluidization velocity, solid circulation rate, axial solid holdup and gas bypassing between the lower loop seal and the gasifier.

Experimental Study and Computational Simulations of Key Pebble Bed Thermo-mechanics Issues for Design and Safety

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokuhiro, Akira; Potirniche, Gabriel; Cogliati, Joshua

2014-07-08

An experimental and computational study, consisting of modeling and simulation (M&S), of key thermal-mechanical issues affecting the design and safety of pebble-bed (PB) reactors was conducted. The objective was to broaden understanding and experimentally validate thermal-mechanic phenomena of nuclear grade graphite, specifically, spheres in frictional contact as anticipated in the bed under reactor relevant pressures and temperatures. The contact generates graphite dust particulates that can subsequently be transported into the flowing gaseous coolent. Under postulated depressurization transients and with the potential for leaked fission products to be adsorbed onto graphite 'dust', there is the potential for fission products to escapemore » from the primary volume. This is a design safety concern. Furthermore, earlier safety assessment identified the distinct possibility for the dispersed dust to combust in contact with air if sufficient conditions are met. Both of these phenomena were noted as important to design review and containing uncertainty to warrant study. The team designed and conducted two separate effects tests to study and benchmark the potential dust-generation rate, as well as study the conditions under which a dust explosion may occure in a standardized, instrumented explosion chamber.« less

Thermofluid effect on energy storage in fluidized bed reactor

NASA Astrophysics Data System (ADS)

Mahfoudi, Nadjiba; El Ganaoui, Mohammed; Moummi, Abdelhafid

2016-05-01

The development of innovative systems of heat storage is imperative to improve the efficiency of the existing systems used in the thermal solar energy applications. Several techniques were developed and realized in this context. The technology of the sand fluidized bed (sandTES) offers a promising alternative to the current state-of-the-art of the heat storage systems, such as fixed bed using a storage materials, as sand, ceramic, and stones, etc. Indeed, the use of the fluidization technique allows an effective heat transfer to the solid particles. With the sand, an important capacity of storage is obtained by an economic and ecological material [N. Mahfoudi, A. Moummi, M. El Ganaoui, Appl. Mech. Mater. 621, 214 (2014); N. Mahfoudi, A. Khachkouch, A. Moummi B. Benhaoua, M. El Ganaoui, Mech. Ind. 16, 411 (2015); N. Mahfoudi, A. Moummi, M. El Ganaoui, F. Mnasri, K.M. Aboudou, 3e Colloque internationale Francophone d"énergétique et mécanique, Comores, 2014, p. 91]. This paper presents a CFD simulation of the hydrodynamics and the thermal transient behavior of a fluidized bed reactor of sand, to determine the characteristics of storage. The simulation shows a symmetry breaking that occurs and gave way to chaotic transient generation of bubble formation after 3 s. Furthermore, the predicted average temperature of the solid phase (sand) increases gradually versus the time with a gain of 1 °C in an interval of 10 s. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

Pebble Bed Reactors Design Optimization Methods and their Application to the Pebble Bed Fluoride Salt Cooled High Temperature Reactor (PB-FHR)

NASA Astrophysics Data System (ADS)

Cisneros, Anselmo Tomas, Jr.

The Fluoride salt cooled High temperature Reactor (FHR) is a class of advanced nuclear reactors that combine the robust coated particle fuel form from high temperature gas cooled reactors, direct reactor auxillary cooling system (DRACS) passive decay removal of liquid metal fast reactors, and the transparent, high volumetric heat capacitance liquid fluoride salt working fluids---flibe (33%7Li2F-67%BeF)---from molten salt reactors. This combination of fuel and coolant enables FHRs to operate in a high-temperature low-pressure design space that has beneficial safety and economic implications. In 2012, UC Berkeley was charged with developing a pre-conceptual design of a commercial prototype FHR---the Pebble Bed- Fluoride Salt Cooled High Temperature Reactor (PB-FHR)---as part of the Nuclear Energy University Programs' (NEUP) integrated research project. The Mark 1 design of the PB-FHR (Mk1 PB-FHR) is 236 MWt flibe cooled pebble bed nuclear heat source that drives an open-air Brayton combine-cycle power conversion system. The PB-FHR's pebble bed consists of a 19.8% enriched uranium fuel core surrounded by an inert graphite pebble reflector that shields the outer solid graphite reflector, core barrel and reactor vessel. The fuel reaches an average burnup of 178000 MWt-d/MT. The Mk1 PB-FHR exhibits strong negative temperature reactivity feedback from the fuel, graphite moderator and the flibe coolant but a small positive temperature reactivity feedback of the inner reflector and from the outer graphite pebble reflector. A novel neutronics and depletion methodology---the multiple burnup state methodology was developed for an accurate and efficient search for the equilibrium composition of an arbitrary continuously refueled pebble bed reactor core. The Burnup Equilibrium Analysis Utility (BEAU) computer program was developed to implement this methodology. BEAU was successfully benchmarked against published results generated with existing equilibrium depletion codes VSOP and PEBBED for a high temperature gas cooled pebble bed reactor. Three parametric studies were performed for exploring the design space of the PB-FHR---to select a fuel design for the PB-FHR] to select a core configuration; and to optimize the PB-FHR design. These parametric studies investigated trends in the dependence of important reactor performance parameters such as burnup, temperature reactivity feedback, radiation damage, etc on the reactor design variables and attempted to understand the underlying reactor physics responsible for these trends. A pebble fuel parametric study determined that pebble fuel should be designed with a carbon to heavy metal ratio (C/HM) less than 400 to maintain negative coolant temperature reactivity coefficients. Seed and thorium blanket-, seed and inert pebble reflector- and seed only core configurations were investigated for annular FHR PBRs---the C/HM of the blanket pebbles and discharge burnup of the thorium blanket pebbles were additional design variable for core configurations with thorium blankets. Either a thorium blanket or graphite pebble reflector is required to shield the outer graphite reflector enough to extend its service lifetime to 60 EFPY. The fuel fabrication costs and long cycle lengths of the thorium blanket fuel limit the potential economic advantages of using a thorium blanket. Therefore, the seed and pebble reflector core configuration was adopted as the baseline core configuration. Multi-objective optimization with respect to economics was performed for the PB-FHR accounting for safety and other physical design constraints derived from the high-level safety regulatory criteria. These physical constraints were applied along in a design tool, Nuclear Application Value Estimator, that evaluated a simplified cash flow economics model based on estimates of reactor performance parameters calculated using correlations based on the results of parametric design studies for a specific PB-FHR design and a set of economic assumptions about the electricity market to evaluate the economic implications of design decisions. The optimal PB-FHR design---Mark 1 PB-FHR---is described along with a detailed summary of its performance characteristics including: the burnup, the burnup evolution, temperature reactivity coefficients, the power distribution, radiation damage distributions, control element worths, decay heat curves and tritium production rates. The Mk1 PB-FHR satisfies the PB-FHR safety criteria. The fuel, moderator (pebble core, pebble shell, graphite matrix, TRISO layers) and coolant have global negative temperature reactivity coefficients and the fuel temperatures are well within their limits.

Dynamic bed reactor

DOEpatents

Stormo, Keith E.

1996-07-02

A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix.

Pyrolysis of softwood carbohydrates in a fluidized bed reactor.

PubMed

Aho, Atte; Kumar, Narendra; Eränen, Kari; Holmbom, Bjarne; Hupa, Mikko; Salmi, Tapio; Murzin, Dmitry Yu

2008-09-01

In the present work pyrolysis of pure pine wood and softwood carbohydrates, namely cellulose and galactoglucomannan (the major hemicellulose in coniferous wood), was conducted in a batch mode operated fluidized bed reactor. Temperature ramping (5 degrees C/min) was applied to the heating until a reactor temperature of 460 degrees C was reached. Thereafter the temperature was kept until the release of non-condensable gases stopped. The different raw materials gave significantly different bio-oils. Levoglucosan was the dominant product in the cellulose pyrolysis oil. Acetic acid was found in the highest concentrations in both the galactoglucomannan and in the pine wood pyrolysis oils. Acetic acid is most likely formed by removal of O-acetyl groups from mannose units present in GGM structure.

Pyrolysis of Softwood Carbohydrates in a Fluidized Bed Reactor

PubMed Central

Aho, Atte; Kumar, Narendra; Eränen, Kari; Holmbom, Bjarne; Hupa, Mikko; Salmi, Tapio; Murzin, Dmitry Yu.

2008-01-01

In the present work pyrolysis of pure pine wood and softwood carbohydrates, namely cellulose and galactoglucomannan (the major hemicellulose in coniferous wood), was conducted in a batch mode operated fluidized bed reactor. Temperature ramping (5 °C/min) was applied to the heating until a reactor temperature of 460 °C was reached. Thereafter the temperature was kept until the release of non-condensable gases stopped. The different raw materials gave significantly different bio-oils. Levoglucosan was the dominant product in the cellulose pyrolysis oil. Acetic acid was found in the highest concentrations in both the galactoglucomannan and in the pine wood pyrolysis oils. Acetic acid is most likely formed by removal of O-acetyl groups from mannose units present in GGM structure. PMID:19325824

In Situ NDA Conformation Measurements Performed at Auxiliary Charcoal Bed and Other Main Charcoal Beds After Uranium Removal from Molten Salt Reactor Experiment ACB at Oak Ridge National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haghighi, M. H.; Kring, C. T.; McGehee, J. T.

2002-02-26

The Molten Salt Reactor Experiment (MSRE) site is located in Tennessee, on the U.S. Department of Energy (DOE) Oak Ridge Reservation (ORR). The MSRE was run by Oak Ridge National Laboratory (ORNL) to demonstrate the desirable features of the molten-salt concept in a practical reactor that could be operated safely and reliably. It introduced the idea of a homogeneous reactor using fuel salt media and graphite moderation for power and breeder reactors. The MSRE reactor and associated components are located in cells beneath the floor in the high-bay area of Building 7503. The reactor was operated from June 1965 tomore » December 1969. When the reactor was shut down, fuel salt was drained from the reactor circuit to two drain tanks. A ''clean'' salt was then circulated through the reactor as a decontamination measure and drained to a third drain tank. When operations ceased, the fuel and flush salts were allowed to cool and solidify in the drain tanks. At shutdown, the MSRE facility complex was placed in a surveillance and maintenance program. Beginning in 1987, it was discovered that gaseous uranium (U-233/U-232) hexafluoride (UF6) had moved throughout the MSRE process systems. The UF6 had been generated when radiolysis in the fluorine salts caused the individual constituents to dissociate to their component atoms, including free fluorine. Some of the free fluorine combined with uranium fluorides (UF4) in the salt to produce UF6. UF6 is gaseous at slightly above ambient temperatures; thus, periodic heating of the fuel salts (which was intended to remedy the radiolysis problems) and simple diffusion had allowed the UF6 to move out of the salt and into the process systems of MSRE. One of the systems that UF6 migrated into due to this process was the offgas system which is vented to the MSRE main charcoal beds and MSRE auxiliary charcoal bed (ACB). Recently, the majority of the uranium laden-charcoal material residing within the ACB was safely and successfully removed using the uranium deposit removal system and equipment. After removal a series of NDA measurements was performed to determine the amount of uranium material remaining in the ACB, the amount of uranium material removed from the ACB, and the amount of uranium material remaining in the uranium removal equipment due to removal activities.« less

Effect on the tritium breeding ratio for a distributed ICRF antenna in a DEMO reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, A., E-mail: albert.garcia.hp@gmail.com; Karlsruhe Institute of Technology; Polytechnic University of Catalonia

The paper reports results of MCNP-5 calculations to assess the effect on the Tritium Breeding Ratio (TBR) when integrating a distributed Ion Cyclotron Range of Frequencies (ICRF) antenna in the blanket of DEMO fusion power reactor. The calculations consider different parameters such as the ICRF covering ratio and the type of breeding blanket including the Helium Cooled Pebble Bed (HCPB) and the Helium Cooled Lithium Lead (HCLL) concepts. For an antenna with a full toroidal circumference of 360°, located poloidally at 40° with a poloidal extension of 1 m, the reduction of the TBR is −0.349% for the HCPB blanket andmore » −0.532% for the HCLL blanket. The distributed ICRF antenna is thus shown to have only a marginal effect on the TBR of the DEMO reactor.« less

Biparticle fluidized bed reactor

DOEpatents

Scott, Charles D.; Marasco, Joseph A.

1995-01-01

A fluidized bed reactor system utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves.

Biparticle fluidized bed reactor

DOEpatents

Scott, Charles D.; Marasco, Joseph A.

1996-01-01

A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary and tertiary particulate phases, continuously introduced and removed simultaneously in the cocurrent and countercurrent mode, act in a role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Means for introducing and removing the sorbent phases include feed screw mechanisms and multivane slurry valves.

Biparticle fluidized bed reactor

DOEpatents

Scott, C.D.; Marasco, J.A.

1995-04-25

A fluidized bed reactor system utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves. 3 figs.

Biparticle fluidized bed reactor

DOEpatents

Scott, C.D.

1993-12-14

A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase is described. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves. 3 figures.

Biparticle fluidized bed reactor

DOEpatents

Scott, C.D.; Marasco, J.A.

1996-02-27

A fluidized bed reactor system is described which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary and tertiary particulate phases, continuously introduced and removed simultaneously in the cocurrent and countercurrent mode, act in a role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Means for introducing and removing the sorbent phases include feed screw mechanisms and multivane slurry valves. 3 figs.

Biparticle fluidized bed reactor

DOEpatents

Scott, Charles D.

1993-01-01

A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves.

Biomass Conversion to Produce Hydrocarbon Liquid Fuel Via Hot-vapor Filtered Fast Pyrolysis and Catalytic Hydrotreating.

PubMed

Wang, Huamin; Elliott, Douglas C; French, Richard J; Deutch, Steve; Iisa, Kristiina

2016-12-25

Lignocellulosic biomass conversion to produce biofuels has received significant attention because of the quest for a replacement for fossil fuels. Among the various thermochemical and biochemical routes, fast pyrolysis followed by catalytic hydrotreating is considered to be a promising near-term opportunity. This paper reports on experimental methods used 1) at the National Renewable Energy Laboratory (NREL) for fast pyrolysis of lignocellulosic biomass to produce bio-oils in a fluidized-bed reactor and 2) at Pacific Northwest National Laboratory (PNNL) for catalytic hydrotreating of bio-oils in a two-stage, fixed-bed, continuous-flow catalytic reactor. The configurations of the reactor systems, the operating procedures, and the processing and analysis of feedstocks, bio-oils, and biofuels are described in detail in this paper. We also demonstrate hot-vapor filtration during fast pyrolysis to remove fine char particles and inorganic contaminants from bio-oil. Representative results showed successful conversion of biomass feedstocks to fuel-range hydrocarbon biofuels and, specifically, the effect of hot-vapor filtration on bio-oil production and upgrading. The protocols provided in this report could help to generate rigorous and reliable data for biomass pyrolysis and bio-oil hydrotreating research.

Biomass Conversion to Produce Hydrocarbon Liquid Fuel Via Hot-vapor Filtered Fast Pyrolysis and Catalytic Hydrotreating

PubMed Central

Wang, Huamin; Elliott, Douglas C.; French, Richard J.; Deutch, Steve; Iisa, Kristiina

2016-01-01

Lignocellulosic biomass conversion to produce biofuels has received significant attention because of the quest for a replacement for fossil fuels. Among the various thermochemical and biochemical routes, fast pyrolysis followed by catalytic hydrotreating is considered to be a promising near-term opportunity. This paper reports on experimental methods used 1) at the National Renewable Energy Laboratory (NREL) for fast pyrolysis of lignocellulosic biomass to produce bio-oils in a fluidized-bed reactor and 2) at Pacific Northwest National Laboratory (PNNL) for catalytic hydrotreating of bio-oils in a two-stage, fixed-bed, continuous-flow catalytic reactor. The configurations of the reactor systems, the operating procedures, and the processing and analysis of feedstocks, bio-oils, and biofuels are described in detail in this paper. We also demonstrate hot-vapor filtration during fast pyrolysis to remove fine char particles and inorganic contaminants from bio-oil. Representative results showed successful conversion of biomass feedstocks to fuel-range hydrocarbon biofuels and, specifically, the effect of hot-vapor filtration on bio-oil production and upgrading. The protocols provided in this report could help to generate rigorous and reliable data for biomass pyrolysis and bio-oil hydrotreating research. PMID:28060311

THR-TH: a high-temperature gas-cooled nuclear reactor core thermal hydraulics code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vondy, D.R.

1984-07-01

The ORNL version of PEBBLE, the (RZ) pebble bed thermal hydraulics code, has been extended for application to a prismatic gas cooled reactor core. The supplemental treatment is of one-dimensional coolant flow in up to a three-dimensional core description. Power density data from a neutronics and exposure calculation are used as the basic information for the thermal hydraulics calculation of heat removal. Two-dimensional neutronics results may be expanded for a three-dimensional hydraulics calculation. The geometric description for the hydraulics problem is the same as used by the neutronics code. A two-dimensional thermal cell model is used to predict temperatures inmore » the fuel channel. The capability is available in the local BOLD VENTURE computation system for reactor core analysis with capability to account for the effect of temperature feedback by nuclear cross section correlation. Some enhancements have also been added to the original code to add pebble bed modeling flexibility and to generate useful auxiliary results. For example, an estimate is made of the distribution of fuel temperatures based on average and extreme conditions regularly calculated at a number of locations.« less

Fuel development for gas-cooled fast reactors

NASA Astrophysics Data System (ADS)

Meyer, M. K.; Fielding, R.; Gan, J.

2007-09-01

The Generation IV Gas-cooled Fast Reactor (GFR) concept is proposed to combine the advantages of high-temperature gas-cooled reactors (such as efficient direct conversion with a gas turbine and the potential for application of high-temperature process heat), with the sustainability advantages that are possible with a fast-spectrum reactor. The latter include the ability to fission all transuranics and the potential for breeding. The GFR is part of a consistent set of gas-cooled reactors that includes a medium-term Pebble Bed Modular Reactor (PBMR)-like concept, or concepts based on the Gas Turbine Modular Helium Reactor (GT-MHR), and specialized concepts such as the Very High-Temperature Reactor (VHTR), as well as actinide burning concepts [A Technology Roadmap for Generation IV Nuclear Energy Systems, US DOE Nuclear Energy Research Advisory Committee and the Generation IV International Forum, December 2002]. To achieve the necessary high power density and the ability to retain fission gas at high temperature, the primary fuel concept proposed for testing in the United States is dispersion coated fuel particles in a ceramic matrix. Alternative fuel concepts considered in the US and internationally include coated particle beds, ceramic clad fuel pins, and novel ceramic 'honeycomb' structures. Both mixed carbide and mixed nitride-based solid solutions are considered as fuel phases.

Minimum-sized ideal reactor for continuous alcohol fermentation using immobilized microorganism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamane, T.; Shimizu, S.

Recently, alcohol fermentation has gained considerable attention with the aim of lowering its production cost in the production processes of both fuel ethanol and alcoholic beverages. The over-all cost is a summation of costs of various subsystems such as raw material (sugar, starch, and cellulosic substances) treatment, fermentation process, and alcohol separation from water solutions; lowering the cost of the fermentation processes is very important in lowering the total cost. Several new techniques have been developed for economic continuous ethanol production, use of a continuous wine fermentor with no mechanical stirring, cell recycle combined with continuous removal of ethanol undermore » vaccum, a technique involving a bed of yeast admixed with an inert carrier, and use of immobilized yeast reactors in packed-bed column and in a three-stage double conical fluidized-bed bioreactor. All these techniques lead to increases more or less, in reactor productivity, which in turn result in the reduction of the reactor size for a given production rate and a particular conversion. Since an improvement in the fermentation process often leads to a reduction of fermentor size and hence, a lowering of the initial construction cost, it is important to theoretically arrive at a solution to what is the minimum-size setup of ideal reactors from the viewpoint of liquid backmixing. In this short communication, the minimum-sized ideal reactor for continuous alcohol fermentation using immobilized cells will be specifically discussed on the basis of a mathematical model. The solution will serve for designing an optimal bioreactor. (Refs. 26).« less

Demonstrating the Effect of Interphase Mass Transfer in a Transparent Fluidized Bed Reactor

ERIC Educational Resources Information Center

Saayman, Jean; Nicol, Willie

2011-01-01

A demonstration experiment is described that employs the ozone decomposition reaction at ambient conditions on Fe2O3 impregnated Fluidized Catalytic Cracking (FCC) catalyst. Using a two-dimensional see-through column the importance of interphase mass transfer is clearly illustrated by the significant difference in ozone conversion between the…

Degradation and COD removal of catechol in wastewater using the catalytic ozonation process combined with the cyclic rotating-bed biological reactor.

PubMed

Aghapour, Ali Ahmad; Moussavi, Gholamreza; Yaghmaeian, Kamyar

2015-07-01

The effect of ozonation catalyzed with MgO/granular activated carbon (MgO/GAC) composite as a pretreatment process on the performance of cyclic rotating-bed biological reactor (CRBR) for the catechol removal from wastewater has been investigated. CRBR with acclimated biomasses could efficiently remove catechol and its related COD from wastewater at organic loading rate (OLR) of 7.82 kg COD/m(3).d (HRT of 9 h). Then, OLR increased to 15.64 kg COD/m(3).d (HRT of 4.5 h) and CRBR failed. Catalytic ozonation process (COP) used as a pre-treatment and could improve the performance of the failed CRBR. The overall removal efficiency of the combined process attained respective steady states of 91% and 79% for degradation and COD removal of catechol. Therefore, the combined process is more effective in degradation and COD removal of catechol; it is also a viable alternative for upgrading industrial wastewater treatment plant. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characteristics of products from fast pyrolysis of fractions of waste square timber and ordinary plywood using a fluidized bed reactor.

PubMed

Jung, Su-Hwa; Kim, Seon-Jin; Kim, Joo-Sik

2012-06-01

Fractions of waste square timber and waste ordinary plywood were pyrolyzed in a pyrolysis plant equipped with a fluidized bed reactor and a dual char separation system. The maximum bio-oil yield of about 65 wt.% was obtained at reaction temperatures of 450-500 °C for both feed materials. For quantitative analysis of bio-oil, the relative response factor (RRF) of each component was calculated using an effective carbon number (ECN) that was multiplied by the peak area of each component detected by a GC-FID. The predominant compounds in the bio-oils were methyl acetate, acids, hydroxyacetone, furfural, non-aromatic ketones, levoglucosan and phenolic compounds. The WOP-derived bio-oil showed it to have relatively high nitrogen content. Increasing the reaction temperature was shown to have little effect on nitrogen removal. The ash and solid contents of both bio-oils were below 0.1 wt.% due to the excellent performance of the char separation system. Copyright © 2012 Elsevier Ltd. All rights reserved.

Pretreatment of vinasse from the sugar refinery industry under non-sterile conditions by Trametes versicolor in a fluidized bed bioreactor and its effect when coupled to an UASB reactor.

PubMed

España-Gamboa, Elda; Vicent, Teresa; Font, Xavier; Dominguez-Maldonado, Jorge; Canto-Canché, Blondy; Alzate-Gaviria, Liliana

2017-01-01

During hydrous ethanol production from the sugar refinery industry in Mexico, vinasse is generated. Phenolic compounds and melanoidins contribute to its color and make degradation of the vinasse a difficult task. Although anaerobic digestion (AD) is feasible for vinasse treatment, the presence of recalcitrant compounds can be toxic or inhibitory for anaerobic microorganism. Therefore, this study presents new data on the coupled of the FBR (Fluidized Bed Bioreactor) to the UASB (Upflow Anaerobic Sludge Blanket) reactor under non-sterile conditions by T. versicolor . Nevertheless, for an industrial application, it is necessary to evaluate the performance in this kind of proposal system. Therefore, this study used a FBR for the removal of phenolic compounds (67%) and COD (38%) at non-sterile conditions. Continuous operation of the FBR was successfully for 26 days according to the literature. When the FBR was coupled to the UASB reactor, we obtained a better quality of effluent, furthermore methane content and yield were 74% and 0.18 m 3 CH 4 / kg COD removal respectively. This study demonstrated the possibility of using for an industrial application the coupled of the FBR to the UASB reactor under non-sterile conditions. Continuous operation of the FBR was carried out successfully for 26 days, which is the highest value found in the literature.

Attrition resistant bulk iron catalysts and processes for preparing and using same

DOEpatents

Jothimurugesan, Kandaswamy [Ponca City, OK; Goodwin, Jr., James G.; Gangwal, Santosh K [Cary, NC

2007-08-21

An attrition resistant precipitated bulk iron catalyst is prepared from iron oxide precursor and a binder by spray drying. The catalysts are preferably used in carbon monoxide hydrogenation processes such as Fischer-Tropsch synthesis. These catalysts are suitable for use in fluidized-bed reactors, transport reactors and, especially, slurry bubble column reactors.

Genetically engineered Escherichia coli FBR5: Part I. Comparison of high cell density bioreactors for enhanced ethanol production from xylose

USDA-ARS?s Scientific Manuscript database

Five reactor systems (free cell batch, free cell continuous, entrapped cell immobilized, adsorbed cell packed bed, and cell recycle membrane reactors) were compared for ethanol production from xylose employing Escherichia coli FBR5. In the free cell batch and free cell continuous reactors (continuo...

Influence of internal biogas production on hydrodynamic behavior of anaerobic fluidized-bed reactors.

PubMed

Wu, Chun-Sheng; Huang, Ju-Sheng; Chou, Hsin-Hsien

2006-01-01

Predictive models for describing the hydrodynamic behavior (bed-expansion and bed-pressure gradient) of a three-phase anaerobic fluidized bed reactor (AFBR) was developed according to wake theory together with more realistic dynamic bed-expansion experiments (with and without internal biogas production). A reliable correlation equation for the parameter k (mean volume ratio of wakes to bubbles) was also established, which is of help in estimating liquid hold up of fluidized beds. The experimental expansion ratio of three-phase fluidized beds (E(GLS)) was approximately 18% higher than that of two-phase fluidized beds (E(LS)); whereas the experimental bed-pressure gradient of the former [(-DeltaP/H)(GLS)] was approximately 9.3% lower than that of the latter [(-DeltaP/H)(LS)]. Both the experimental and modeling results indicated that a higher superficial gas velocity (u(g)) gave a higher E(GLS) and a higher E(GLS) to E(LS) ratio as well as a lower (-DeltaP/H)(GLS) and a lower (-DeltaP/H)(GLS) to (-DeltaP/H)(LS) ratio. As for the operation stability of the AFBR, the sensitivity of u(g) to expansion height (H(GLS)) and (-DeltaP/H)(GLS) is between the sensitivity of superficial liquid velocity and biofilm thickness. The model predictions of E(GLS), (-DeltaP)(GLS), and (-DeltaP/H)(GLS) agreed well the experimental measurements. Accordingly, the predictive models accounting for internal biogas production described fairly well the hydrodynamic behavior of the AFBR.

Improvement of yields and rates during enzymatic hydrolysis of cellulose to glucose. Progress report, March 1, 1979-May 31, 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundstrom, D W; Klei, H E; Coughlin, R W

1979-05-01

The objective of this program is to show that the conversion of cellulose to glucose can be significantly increased by enzymatically removing the inhibitory cellobiose from the reaction system using immobilized ..beta..-glucosidase (..beta..-G). An enzymatic catalyst was prepared and used in a fluidized bed with cellobiose as the substrate, only a 10% loss of activity was observed during a 500 hour period. Cellulose was hydrolyzed in two batch reactors operated side-by-side, with one reactor containing immobilized ..beta..-G and cellulose and the other reactor containing an equal amount of cellulose only. After 30 hours the reactor containing the immobilized ..beta..-G hadmore » 100% more glucose, indicating that the catalytic removal of the cellobiose had a significant effect upon the production of glucose.« less

Cyclic process for producing methane from carbon monoxide with heat removal

DOEpatents

Frost, Albert C.; Yang, Chang-lee

1982-01-01

Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

Enzymatic synthesis of ethyl esters from waste oil using mixtures of lipases in a plug-flow packed-bed continuous reactor.

PubMed

Kathiele Poppe, Jakeline; Matte, Carla Roberta; Olave de Freitas, Vitória; Fernandez-Lafuente, Roberto; Rodrigues, Rafael C; Záchia Ayub, Marco Antônio

2018-04-30

This work describes the continuous synthesis of ethyl esters via enzymatic catalysis on a packed-bed continuous reactor, using mixtures of immobilized lipases (combi-lipases) of Candida antarctica (CALB), Thermomyces lanuginosus (TLL), and Rhizomucor miehei (RML). The influence of the addition of glass beads to the reactor bed, evaluation of the use of different solvents, and flow rate on reaction conditions were studied. All experiments were conducted using the best combination of lipases according to the fatty acid composition of the waste oil (combi-lipase composition: 40% of TLL, 35% of CALB, and 25% of RML), and soybean oil (combi-lipase composition: 22.5% of TLL, 50% of CALB, and 27.5% of RML). The best general reaction conditions were found to be using tert-butanol as solvent, and the flow rate of 0.08 mL min -1 . The combi-lipase reactors operating at steady state for over 30 days (720 h), kept conversion yields of approximately 50%, with average productivity of 1.94 g ethyl esters g substrate -1 h -1 , regardless of the type of oil in use. This article is protected by copyright. All rights reserved. © 2018 American Institute of Chemical Engineers.

An Experimental Investigation of Sewage Sludge Gasification in a Fluidized Bed Reactor

PubMed Central

Calvo, L. F.; García, A. I.; Otero, M.

2013-01-01

The gasification of sewage sludge was carried out in a simple atmospheric fluidized bed gasifier. Flow and fuel feed rate were adjusted for experimentally obtaining an air mass : fuel mass ratio (A/F) of 0.2 < A/F < 0.4. Fuel characterization, mass and power balances, produced gas composition, gas phase alkali and ammonia, tar concentration, agglomeration tendencies, and gas efficiencies were assessed. Although accumulation of material inside the reactor was a main problem, this was avoided by removing and adding bed media along gasification. This allowed improving the process heat transfer and, therefore, gasification efficiency. The heating value of the produced gas was 8.4 MJ/Nm, attaining a hot gas efficiency of 70% and a cold gas efficiency of 57%. PMID:24453863

Removal of oxides of nitrogen from gases in multi-stage coal combustion

DOEpatents

Mollot, D.J.; Bonk, D.L.; Dowdy, T.E.

1998-01-13

Polluting NO{sub x} gas values are removed from off-gas of a multi-stage coal combustion process which includes an initial carbonizing reaction, firing of char from this reaction in a fluidized bed reactor, and burning of gases from the carbonizing and fluidized bed reactions in a topping combustor having a first, fuel-rich zone and a second, fuel-lean zone. The improvement by means of which NO{sub x} gases are removed is directed to introducing NO{sub x}-free oxidizing gas such as compressor air into the second, fuel-lean zone and completing combustion with this source of oxidizing gas. Excess air fed to the fluidized bed reactor is also controlled to obtain desired stoichiometry in the first, fuel-rich zone of the topping combustor. 2 figs.

Removal of oxides of nitrogen from gases in multi-stage coal combustion

DOEpatents

Mollot, Darren J.; Bonk, Donald L.; Dowdy, Thomas E.

1998-01-01

Polluting NO.sub.x gas values are removed from off-gas of a multi-stage coal combustion process which includes an initial carbonizing reaction, firing of char from this reaction in a fluidized bed reactor, and burning of gases from the carbonizing and fluidized bed reactions in a topping combustor having a first, fuel-rich zone and a second, fuel-lean zone. The improvement by means of which NO.sub.x gases are removed is directed to introducing NO.sub.x -free oxidizing gas such as compressor air into the second, fuel-lean zone and completing combustion with this source of oxidizing gas. Excess air fed to the fluidized bed reactor is also controlled to obtain desired stoichiometry in the first, fuel-rich zone of the topping combustor.

Performance and application of a fluidized bed limestone reactor designed for control of alkalinity, hardness and pH at the Warm Springs Regional Fisheries Center

USGS Publications Warehouse

Watten, Barnaby J.; Mudrak, Vincent A.; Echevarria, Carlos; Sibrell, Philip; Summerfelt, Steven T.; Boyd, Claude E.

2017-01-01

Springs serving the Warm Springs Regional Fisheries Center, Warm Springs, Georgia, have pH, alkalinity, and hardness levels thatlie under the range required for successful fish propagation while free CO2 is well above allowable targets. We evaluate a pretreatment process that exploits limestone’s (CaCO3) ability to react away hydrogen ions (H+) and carbon dioxide (CO2) while increasing alkalinity (HCO3−) and calcium (Ca2+) concentrations, i.e. CaCO3 + H+ ↔ HCO3− + Ca2+ CaCO3 + CO2 + H2O ↔ Ca2+ + 2HCO3− Limestone sand was tested in both pilot and full scale fluidized bed reactors (CycloBio®). We first established the bed expansion characteristics of three commercial limestone products then evaluated the effect of hydraulic flux and bed height on dissolution rate of a single selected product (Type A16 × 120). Pilot scale testing at 18C showed limestone dissolution rates were relatively insensitive to flux over the range 1.51–3.03 m3/min/m2 but were sensitive (P < 0.001; R2 = 0.881) to changes in bed height (BH, cm) over the range 83–165 cm following the relation: (Alkalinity, mg/L) = 123.51 − (3788.76 (BH)). Differences between filtered and non-filtered alkalinity were small(P > 0.05) demonstrating that limestone was present in the reactor effluent primarily in the form of dissolved Ca(HCO3)2. Effluent alkalinity exceeded our target level of 50 mg/L under most operating conditions evaluated with typical pilot scale values falling within the range of 90–100 mg/L despite influent concentrations of about 4 mg/L. Concurrently, CO2 fell from an average of 50.6 mg/L to 8.3 mg/L (90%), providing for an increase in pH from 5.27 to a mean of 7.71. The ability of the test reactor to provide changes in water chemistry variables that exceeded required changes allowed for a dilution ratio of 0.6. Here, alkalinity still exceeded 50 mg/L, the CO2 concentration remained well below our limit of 20 mg/L (15.4 mg/L) and the pH was near neutral (7.17). Applying the dilution ratio of 0.6 in a full scale treatment plant at the site reduced by 40% the volume of spring water that is directed through each of three parallel reactors that combined react away 49,000 kg of limestone/yr.

Biodegradation of pharmaceuticals in hospital wastewater by staged Moving Bed Biofilm Reactors (MBBR).

PubMed

Casas, Mònica Escolà; Chhetri, Ravi Kumar; Ooi, Gordon; Hansen, Kamilla M S; Litty, Klaus; Christensson, Magnus; Kragelund, Caroline; Andersen, Henrik R; Bester, Kai

2015-10-15

Hospital wastewater represents a significant input of pharmaceuticals into municipal wastewater. As Moving Bed Biofilm Reactors (MBBRs) appear to remove organic micro-pollutants, hospital wastewater was treated with a pilot plant consisting of three MBBRs in series. The removal of pharmaceuticals was studied in two experiments: 1) A batch experiment where pharmaceuticals were spiked to each reactor and 2) a continuous flow experiment at native concentrations. DOC removal, nitrification as well as removal of pharmaceuticals (including X-ray contrast media, β-blockers, analgesics and antibiotics) occurred mainly in the first reactor. In the batch experiment most of the compounds followed a single first-order kinetics degradation function, giving degradation rate constants ranged from 5.77 × 10(-3) to 4.07 h(-1), from -5.53 × 10(-3) to 9.24 × 10(-1) h(-1) and from 1.83 × 10(-3) to 2.42 × 10(-1) h(-1) for first, second and third reactor respectively. Generally, the highest removal rate constants were found in the first reactor while the lowest were found in the third one. This order was inverted for most compounds, when the removal rate constants were normalized to biomass, indicating that the last tank had the most effective biofilms. In the batch experiment, 21 out of 26 compounds were assessed to be degraded with more than 20% within the MBBR train. In the continuous flow experiment the measured removal rates were lower than those estimated from the batch experiments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of combustion temperature on PCDD/Fs formation in laboratory-scale fluidized-bed incineration.

PubMed

Hatanaka, T; Imagawa, T; Kitajima, A; Takeuchi, M

2001-12-15

Combustion experiments in a laboratory-scale fluidized-bed reactor were performed to elucidate the effects of combustion temperature on PCDD/Fs formation during incineration of model wastes with poly(vinyl chloride) or sodium chloride as a chlorine source and copper chloride as a catalyst. Each temperature of primary and secondary combustion zones in the reactor was set independently to 700, 800, and 900 degrees C using external electric heaters. The PCDD/Fs concentration is reduced as the temperature of the secondary combustion zone increases. It is effective to keep the temperature of the secondary combustion zone high enough to reduce their release during the waste incineration. On the other hand, as the temperature of the primary combustion zone rises, the PCDD/Fs concentration also increases. Lower temperature of the primary combustion zone results in less PCDD/Fs concentration in these experimental conditions. This result is probably related to the devolatilization rate of the solid waste in the primary combustion zone. The temperature decrease slows the devolatilization rate and promotes mixing of oxygen and volatile matters from the solid waste. This contributes to completing combustion reactions, resulting in reducing the PCDD/Fs concentration.

High-Purity Silicon Seeds for Silane Pyrolysis

NASA Technical Reports Server (NTRS)

Hsu, G. C.; Rohatgi, N. K.; Morrison, A.

1985-01-01

Seed particles for fluidized-bed production of silicon made by new contamination-free, economical method. In new method, large particles of semiconductor-grade silicon fired at each other by high-speed streams of gas and thereby break up into particles of suitable size for fluidized bed. No foreign materials introduced, and leaching unnecessary. Method used to feed fluidized-bed reactor for continuous production of high-purity silicon.

Characterization of limestone reacted with acid-mine drainage in a pulsed limestone bed treatment system at the Friendship Hill National Historical Site, Pennsylvania, USA

USGS Publications Warehouse

Hammarstrom, J.M.; Sibrell, P.L.; Belkin, H.E.

2003-01-01

Armoring of limestone is a common cause of failure in limestone-based acid-mine drainage (AMD) treatment systems. Limestone is the least expensive material available for acid neutralization, but is not typically recommended for highly acidic, Fe-rich waters due to armoring with Fe(III) oxyhydroxide coatings. A new AMD treatment technology that uses CO2 in a pulsed limestone bed reactor minimizes armor formation and enhances limestone reaction with AMD. Limestone was characterized before and after treatment with constant flow and with the new pulsed limestone bed process using AMD from an inactive coal mine in Pennsylvania (pH = 2.9, Fe = 150 mg/l, acidity = 1000 mg/l CaCO3). In constant flow experiments, limestone is completely armored with reddish-colored ochre within 48 h of contact in a fluidized bed reactor. Effluent pH initially increased from the inflow pH of 2.9 to over 7, but then decreased to 6 during operation. Limestone removed from a pulsed bed pilot plant is a mixture of unarmored, rounded and etched limestone grains and partially armored limestone and refractory mineral grains (dolomite, pyrite). The ???30% of the residual grains in the pulsed flow reactor that are armored have thicker (50- to 100-??m), more aluminous coatings and lack the gypsum rind that develops in the constant flow experiment. Aluminium-rich zones developed in the interior parts of armor rims in both the constant flow and pulsed limestone bed experiments in response to pH changes at the solid/solution interface. ?? 2003 Elsevier Ltd. All rights reserved.

Fischer-Tropsch synthesis from a low H/sub 2/:CO gas in a dry fluidized-bed system. Volume 2. Development of microreactor systems for unsteady-state Fischer-Tropsch synthesis. Final technical report. [408 references

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whiting, G.K.; Liu, Y.A.; Squires, A.M.

1986-10-01

Vibrofluidized microreactor systems have been developed for studies of unsteady-state Fischer-Tropsch synthesis. This development is aimed at preventing carbon deposition on a fused-iron catalyst in a novel reactor called the ''heat tray.'' This reactor involves a supernatant gas flowing over a shallow fluidized bed of catalyst particles. Three systems were built: (1) a vibrofluidized-bed microreactor system for obtaining baseline carbon deposition information under industrially important reaction conditions; (2) a sliding-plug vibrofluidized-bed microreactor system for rapid switching of feed gases in the F-T synthesis; and (3) a cold-flow microreactor model for studying the gas mixing characteristics of the sliding-plug vibrofluidized-bed microreactor.more » The results show that catalyst defluidization occurred under steady-state synthesis conditions below 395 C using a feed gas of H/sub 2//CO ratio of 2:1 or less. Above 395 C, the probability of hydrocarbon chain growth (..cap alpha.. < 0.50 to prevent accumulation of high-molecular-weight species that cause defluidization. Carbon deposition was rapid above 395 C when a feed gas of H/sub 2//CO ratio of 2:1 or less was used. Cold-flow microreactor model studies show that rapid (on the order of seconds), quantitative switching of feed gases over a vibrofluidized bed of catalyst could be achieved. Vibrofluidization of the catalyst bed induced little backmixing of feed gas over the investigated flow-rate range of 417 to 1650 actual mm/sup 3//s. Further, cold-flow microreactor model studies showed intense solid mixing when a bed of fused-iron catalyst (150 to 300 microns) was vibrofluidized at 24 cycles per second with a peak-to-peak amplitude of 4 mm. The development of the microreactor systems provided an easy way of accurately determining integral fluid-bed kinetics in a laboratory reactor. 408 refs., 156 figs., 27 tabs.« less

Gaseous hexane biodegradation by Fusarium solani in two liquid phase packed-bed and stirred-tank bioreactors.

PubMed

Arriaga, Sonia; Muñoz, Raúl; Hernández, Sergio; Guieysse, Benoit; Revah, Sergio

2006-04-01

Biofiltration of hydrophobic volatile pollutants is intrinsically limited by poor transfer of the pollutants from the gaseous to the liquid biotic phase, where biodegradation occurs. This study was conducted to evaluate the potential of silicone oil for enhancing the transport and subsequent biodegradation of hexane by the fungus Fusarium solani in various bioreactor configurations. Silicone oil was first selected among various solvents for its biocompatibility, nonbiodegradability, and good partitioning properties toward hexane. In batch tests, the use of silicone oil improved hexane specific biodegradation by approximately 60%. Subsequent biodegradation experiments were conducted in stirred-tank (1.5 L) and packed-bed (2.5 L) bioreactors fed with a constant gaseous hexane load of 180 g x m(-3)(reactor) x h(-1) and operated for 12 and 40 days, respectively. In the stirred reactors, the maximum hexane elimination capacity (EC) increased from 50 g x m(-3)(reactor) x h(-1) (removal efficiency, RE of 28%) in the control not supplied with silicone oil to 120 g x m(-3)(reactor) x h(-1) in the biphasic system (67% RE). In the packed-bed bioreactors, the maximum EC ranged from 110 (50% RE) to 180 g x m(-3)(reactor) x h(-1) (> 90% RE) in the control and two-liquid-phase systems, respectively. These results represent, to the best of our knowledge, the first reported case of fungi use in a two-liquid-phase bioreactor and the highest hexane removal capacities so far reported in biofilters.

Biofilm Effect on Flow Structure over a Permeable Bed

NASA Astrophysics Data System (ADS)

Kazemifar, F.; Blois, G.; Aybar, M.; Perez-Calleja, P.; Nerenberg, R.; Sinha, S.; Hardy, R. J.; Best, J.; Sambrook Smith, G.; Christensen, K. T.

2017-12-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces in natural and industrial settings, such as water distribution systems and riverbeds among others. The permeable, heterogeneous, and deformable structure of biofilms can influence mass and momentum transport between the subsurface and freestream. However, this interaction is not fully understood, in part due to technical obstacles impeding quantitative experimental investigations. In this work, the effect of biofilm on flow structure over a permeable bed is studied. Experiments are conducted in a closed water channel equipped with an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent recirculating reactor for biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

Biological hydrogen production by Clostridium acetobutylicum in an unsaturated flow reactor.

PubMed

Zhang, Husen; Bruns, Mary Ann; Logan, Bruce E

2006-02-01

A mesophilic unsaturated flow (trickle bed) reactor was designed and tested for H2 production via fermentation of glucose. The reactor consisted of a column packed with glass beads and inoculated with a pure culture (Clostridium acetobutylicum ATCC 824). A defined medium containing glucose was fed at a flow rate of 1.6 mL/min (0.096 L/h) into the capped reactor, producing a hydraulic retention time of 2.1 min. Gas-phase H2 concentrations were constant, averaging 74 +/- 3% for all conditions tested. H2 production rates increased from 89 to 220 mL/hL of reactor when influent glucose concentrations were varied from 1.0 to 10.5 g/L. Specific H2 production rate ranged from 680 to 1270 mL/g glucose per liter of reactor (total volume). The H2 yield was 15-27%, based on a theoretical limit by fermentation of 4 moles of H2 from 1 mole of glucose. The major fermentation by-products in the liquid effluent were acetate and butyrate. The reactor rapidly (within 60-72 h) became clogged with biomass, requiring manual cleaning of the system. In order to make long-term operation of the reactor feasible, biofilm accumulation in the reactor will need to be controlled through some process such as backwashing. These tests using an unsaturated flow reactor demonstrate the feasibility of the process to produce high H2 gas concentrations in a trickle-bed type of reactor. A likely application of this reactor technology could be H2 gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

Process integration for biological sulfate reduction in a carbon monoxide fed packed bed reactor.

PubMed

Kumar, Manoj; Sinharoy, Arindam; Pakshirajan, Kannan

2018-08-01

This study examined immobilized anaerobic biomass for sulfate reduction using carbon monoxide (CO) as the sole carbon source under batch and continuous fed conditions. The immobilized bacteria with beads made of 10% polyvinyl alcohol (PVA) showed best results in terms of sulfate reduction (84 ± 3.52%) and CO utilization (98 ± 1.67%). The effect of hydraulic retention time (HRT), sulfate loading rate and CO loading rate on sulfate and CO removal was investigated employing a 1L packed bed bioreactor containing the immobilized biomass. At 48, 24 and 12 h HRT, the sulfate removal was 94.42 ± 0.15%, 89.75 ± 0.47% and 61.08 ± 0.34%, respectively, along with a CO utilization of more than 90%. The analysis of variance (ANOVA) of the results obtained showed that only the initial CO concentration significantly affected the sulfate reduction process. The reactor effluent sulfate concentrations were 27.41 ± 0.44, 59.16 ± 1.08, 315.83 ± 7.33 mg/L for 250, 500 and 1000 mg/L of influent sulfate concentrations respectively, under the optimum operating conditions. The sulfate reduction rates matched well with low inlet sulfate loading rates, indicating stable performance of the bioreactor system. Overall, this study yielded very high sulfate reduction efficiency by the immobilized anaerobic biomass under high CO loading condition using the packed bed reactor system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrical Capacitance Volume Tomography for the Packed Bed Reactor ISS Flight Experiment

NASA Technical Reports Server (NTRS)

Marashdeh, Qussai; Motil, Brian; Wang, Aining; Liang-Shih, Fan

2013-01-01

Fixed packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a highly desirable unit operation for long duration life support systems in space. NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. To validate these models, the instantaneous distribution of the gas and liquid phases must be measured.Electrical Capacitance Volume Tomography (ECVT) is a non-invasive imaging technology recently developed for multi-phase flow applications. It is based on distributing flexible capacitance plates on the peripheral of a flow column and collecting real-time measurements of inter-electrode capacitances. Capacitance measurements here are directly related to dielectric constant distribution, a physical property that is also related to material distribution in the imaging domain. Reconstruction algorithms are employed to map volume images of dielectric distribution in the imaging domain, which is in turn related to phase distribution. ECVT is suitable for imaging interacting materials of different dielectric constants, typical in multi-phase flow systems. ECVT is being used extensively for measuring flow variables in various gas-liquid and gas-solid flow systems. Recent application of ECVT include flows in risers and exit regions of circulating fluidized beds, gas-liquid and gas-solid bubble columns, trickle beds, and slurry bubble columns. ECVT is also used to validate flow models and CFD simulations. The technology is uniquely qualified for imaging phase concentrations in packed bed reactors for the ISS flight experiments as it exhibits favorable features of compact size, low profile sensors, high imaging speed, and flexibility to fit around columns of various shapes and sizes. ECVT is also safer than other commonly used imaging modalities as it operates in the range of low frequencies (1 MHz) and does not radiate radioactive energy. In this effort, ECVT is being used to image flow parameters in a packed bed reactor for an ISS flight experiment.

Influence of carrier filling ratio on the performance of moving bed biofilm reactor in treating coking wastewater.

PubMed

Gu, Qiyuan; Sun, Tichang; Wu, Gen; Li, Mingyue; Qiu, Wei

2014-08-01

This study aims to evaluate the effect of carrier filling ratio on the performance of a moving bed biofilm reactor in degrading chemical oxygen demand, phenol, thiocyanate, and ammonia from coking wastewater at 20h of hydraulic retention time. The operational experiments under different carrier filling ratios ranging from 20% to 60% were investigated. The maximum removal efficiency of 89%, 99% and 99% for COD, phenol and thiocyanate, and minimum sensitivity to the increasing contaminants concentration in the influent were achieved at 50% carrier filling ratio. The Haldane competitive substrate inhibition kinetics model was used to describe the relationship between the oxygen uptake rate of ammonium oxidizers and the concentration of free ammonium. The highest biofilm microbial community functional diversity (Shannon's diversity index, H') and evenness (Shannon's evenness index, E') were obtained at 50% carrier filling ratio in all runs using a Biolog ECO microplate. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparative analysis of the bacterial diversity in a lab-scale moving bed biofilm reactor (MBBR) applied to treat urban wastewater under different operational conditions.

PubMed

Calderón, Kadiya; Martín-Pascual, Jaime; Poyatos, José Manuel; Rodelas, Belén; González-Martínez, Alejandro; González-López, Jesús

2012-10-01

Different types of carriers were tested as support material in a lab-scale moving bed biofilm reactor (MBBR) used to treat urban wastewater under three different conditions of hydraulic retention time (HRT) and carrier filling ratios (FR). The bacterial diversity developed on the biofilms responsible of the treatment was studied using a cultivation-independent approach based on the polymerase chain reaction-temperature gradient gel electrophoresis technique (PCR-TGGE). Cluster analysis of TGGE fingerprints showed significant differences of community structure dependent upon the different operational conditions applied. Redundancy analysis (RDA) was used to determine the relationship between the operational conditions (type of carrier, HRT, FR) and bacterial biofilm diversity, demonstrating a significant effect of FR=50%. Phylogenetic analysis of PCR-reamplified and sequenced TGGE bands revealed that the prevalent Bacteria populations in the biofilm were related to Betaproteobacteria (46%), Firmicutes (34%),Alphaproteobacteria (14%) and Gammaproteobacteria (9%). Copyright © 2012 Elsevier Ltd. All rights reserved.

Allothermal steam gasification of biomass in cyclic multi-compartment bubbling fluidized-bed gasifier/combustor - new reactor concept.

PubMed

Iliuta, Ion; Leclerc, Arnaud; Larachi, Faïçal

2010-05-01

A new reactor concept of allothermal cyclic multi-compartment fluidized bed steam biomass gasification is proposed and analyzed numerically. The concept combines space and time delocalization to approach an ideal allothermal gasifier. Thermochemical conversion of biomass in periodic time and space sequences of steam biomass gasification and char/biomass combustion is simulated in which the exothermic combustion compartments provide heat into an array of interspersed endothermic steam gasification compartments. This should enhance unit heat integration and thermal efficiency and procure N(2)-free biosyngas with recourse neither to oxygen addition in steam gasification nor contact between flue and syngas. The dynamic, one-dimensional, multi-component, non-isothermal model developed for this concept accounts for detailed solid and gas flow dynamics whereupon gasification/combustion reaction kinetics, thermal effects and freeboard-zone reactions were tied. Simulations suggest that allothermal operation could be achieved with switch periods in the range of a minute supporting practical feasibility for portable small-scale gasification units. Copyright 2009 Elsevier Ltd. All rights reserved.

In-situ upgrading of biomass pyrolysis vapors: catalyst screening on a fixed bed reactor.

PubMed

Stefanidis, S D; Kalogiannis, K G; Iliopoulou, E F; Lappas, A A; Pilavachi, P A

2011-09-01

In-situ catalytic upgrading of biomass fast pyrolysis vapors was performed in a fixed bed bench-scale reactor at 500°C, for catalyst screening purposes. The catalytic materials tested include a commercial equilibrium FCC catalyst (E-cat), various commercial ZSM-5 formulations, magnesium oxide and alumina materials with varying specific surface areas, nickel monoxide, zirconia/titania, tetragonal zirconia, titania and silica alumina. The bio-oil was characterized measuring its water content, the carbon-hydrogen-oxygen (by difference) content and the chemical composition of its organic fraction. Each catalytic material displayed different catalytic effects. High surface area alumina catalysts displayed the highest selectivity towards hydrocarbons, yielding however low organic liquid products. Zirconia/titania exhibited good selectivity towards desired compounds, yielding higher organic liquid product than the alumina catalysts. The ZSM-5 formulation with the highest surface area displayed the most balanced performance having a moderate selectivity towards hydrocarbons, reducing undesirable compounds and producing organic liquid products at acceptable yields. Copyright © 2011 Elsevier Ltd. All rights reserved.

Lewis Research Center's coal-fired, pressurized, fluidized-bed reactor test facility

NASA Astrophysics Data System (ADS)

Kobak, J. A.; Rollbuhler, R. J.

1981-10-01

A 200-kilowatt-thermal, pressurized, fluidized-bed (PFB) reactor, research test facility was designed, constructed, and operated as part of a NASA-funded project to assess and evaluate the effect of PFB hot-gas effluent on aircraft turbine engine materials that might have applications in stationary-power-plant turbogenerators. Some of the techniques and components developed for this PFB system are described. One of the more important items was the development of a two-in-one, gas-solids separator that removed 95+ percent of the solids in 1600 F to 1900 F gases. Another was a coal and sorbent feed and mixing system for injecting the fuel into the pressurized combustor. Also important were the controls and data-acquisition systems that enabled one person to operate the entire facility. The solid, liquid, and gas sub-systems all had problems that were solved over the 2-year operating time of the facility, which culminated in a 400-hour, hot-gas, turbine test.

Lewis Research Center's coal-fired, pressurized, fluidized-bed reactor test facility

NASA Technical Reports Server (NTRS)

Kobak, J. A.; Rollbuhler, R. J.

1981-01-01

A 200-kilowatt-thermal, pressurized, fluidized-bed (PFB) reactor, research test facility was designed, constructed, and operated as part of a NASA-funded project to assess and evaluate the effect of PFB hot-gas effluent on aircraft turbine engine materials that might have applications in stationary-power-plant turbogenerators. Some of the techniques and components developed for this PFB system are described. One of the more important items was the development of a two-in-one, gas-solids separator that removed 95+ percent of the solids in 1600 F to 1900 F gases. Another was a coal and sorbent feed and mixing system for injecting the fuel into the pressurized combustor. Also important were the controls and data-acquisition systems that enabled one person to operate the entire facility. The solid, liquid, and gas sub-systems all had problems that were solved over the 2-year operating time of the facility, which culminated in a 400-hour, hot-gas, turbine test.

A simplified DEM-CFD approach for pebble bed reactor simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y.; Ji, W.

In pebble bed reactors (PBR's), the pebble flow and the coolant flow are coupled with each other through coolant-pebble interactions. Approaches with different fidelities have been proposed to simulate similar phenomena. Coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) approaches are widely studied and applied in these problems due to its good balance between efficiency and accuracy. In this work, based on the symmetry of the PBR geometry, a simplified 3D-DEM/2D-CFD approach is proposed to speed up the DEM-CFD simulation without significant loss of accuracy. Pebble flow is simulated by a full 3-D DEM, while the coolant flow field is calculatedmore » with a 2-D CFD simulation by averaging variables along the annular direction in the cylindrical geometry. Results show that this simplification can greatly enhance the efficiency for cylindrical core, which enables further inclusion of other physics such as thermal and neutronic effect in the multi-physics simulations for PBR's. (authors)« less

Biomass characteristics and simultaneous nitrification-denitrification under long sludge retention time in an integrated reactor treating rural domestic sewage.

PubMed

Gong, Lingxiao; Jun, Li; Yang, Qing; Wang, Shuying; Ma, Bin; Peng, Yongzhen

2012-09-01

In this work, a novel integrated reactor incorporating anoxic fixed bed biofilm reactor (FBBR), oxic moving bed biofilm reactor (MBBR) and settler sequentially was proposed for nitrogen removal from rural domestic sewage. For purposes of achieving high efficiency, low costs and easy maintenance, biomass characteristics and simultaneous nitrification-denitrification (SND) were investigated under long sludge retention time during a 149-day period. The results showed that enhanced SND with proportions of 37.7-42.2% tapped the reactor potentials of efficiency and economy both, despite of C/N ratio of 2.5-4.0 in influent. TN was removed averagely by 69.3% at least, even under internal recycling ratio of 200% and less proportions of biomass assimilation (<3%). Consequently, lower internal recycle and intermittent wasted sludge discharge were feasible to save costs, together with cancellations of sludge return and anoxic stir. Furthermore, biomass with low observed heterotrophic yields (0.053 ± 0.035 g VSS/g COD) and VSS/TSS ratio (<0.55) in MBBR, simplified wasted sludge disposal. Copyright © 2012 Elsevier Ltd. All rights reserved.

Performance evaluation and phylogenetic characterization of anaerobic fluidized bed reactors using ground tire and pet as support materials for biohydrogen production.

PubMed

Barros, Aruana Rocha; Adorno, Maria Angela Tallarico; Sakamoto, Isabel Kimiko; Maintinguer, Sandra Imaculada; Varesche, Maria Bernadete Amâncio; Silva, Edson Luiz

2011-02-01

This study evaluated two different support materials (ground tire and polyethylene terephthalate [PET]) for biohydrogen production in an anaerobic fluidized bed reactor (AFBR) treating synthetic wastewater containing glucose (4000 mg L(-1)). The AFBR, which contained either ground tire (R1) or PET (R2) as support materials, were inoculated with thermally pretreated anaerobic sludge and operated at a temperature of 30°C. The AFBR were operated with a range of hydraulic retention times (HRT) between 1 and 8h. The reactor R1 operating with a HRT of 2h showed better performance than reactor R2, reaching a maximum hydrogen yield of 2.25 mol H(2)mol(-1) glucose with 1.3mg of biomass (as the total volatile solids) attached to each gram of ground tire. Subsequent 16S rRNA gene sequencing and phylogenetic analysis of particle samples revealed that reactor R1 favored the presence of hydrogen-producing bacteria such as Clostridium, Bacillus, and Enterobacter. Copyright © 2010 Elsevier Ltd. All rights reserved.

Nutrients removal in hybrid fluidised bed bioreactors operated with aeration cycles.

PubMed

Martin, Martin; Enríquez, L López; Fernández-Polanco, M; Villaverde, S; Garcia-Encina, P A

2007-01-01

Abstract Two hybrid fluidised bed reactors filled with sepiolite and granular activated carbon (GAC) were operated with short cycled aeration for removing organic matter, total nitrogen and phosphorous, respectively. Both reactors were continuously operated with synthetic and/or industrial wastewater containing 350-500 mg COD/L, 110-130 mg NKT/L, 90-100 mg NH3-N/L and 12-15 mg P/L for 8 months. The reactor filled with sepiolite, treating only synthetic wastewater, removed COD, ammonia, total nitrogen and phosphorous up to 88, 91, 55 and 80% with a hydraulic retention time (HRT) of 10 h, respectively. These efficiencies correspond to removal rates of 0.95 kgCODm(-3)d(-1) and 0.16 kg total N m(-3)d(-1). The reactor filled with GAC was operated for 4 months with synthetic wastewater and 4 months with industrial wastewater, removing 98% of COD, 96% of ammonia, and 66% of total nitrogen, with an HRT of 13.6 h. No significant phosphorous removing activity was observed in this reactor. Microbial communities growing with both reactors were followed using polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) techniques. The microbial fingerprints, i.e. DGGE profiles, indicated that biological communities in both reactors were stable along the operational period even when the operating conditions were changed.

Evaluating the biogas potential of the dry fraction from pretreatment of food waste from households.

PubMed

Murto, Marika; Björnsson, Lovisa; Rosqvist, Håkan; Bohn, Irene

2013-05-01

At the waste handling company NSR, Helsingborg, Sweden, the food waste fraction of source separated municipal solid waste is pretreated to obtain a liquid fraction, which is used for biogas production, and a dry fraction, which is at present incinerated. This pretreatment and separation is performed to remove impurities, however also some of the organic material is removed. The possibility of realising the methane potential of the dry fraction through batch-wise dry anaerobic digestion was investigated. The anaerobic digestion technique used was a two-stage process consisting of a static leach bed reactor and a methane reactor. Treatment of the dry fraction alone and in a mixture with structural material was tested to investigate the effect on the porosity of the leach bed. A tracer experiment was carried out to investigate the liquid flow through the leach beds, and this method proved useful in demonstrating a more homogenous flow through the leach bed when structural material was added. Addition of structural material to the dry fraction was needed to achieve a functional digestion process. A methane yield of 98 m3/ton was obtained from the dry fraction mixed with structural material after 76 days of digestion. This was in the same range as obtained in the laboratory scale biochemical methane potential test, showing that it was possible to extract the organic content in the dry fraction in this type of dry digestion system for the production of methane. Copyright © 2013 Elsevier Ltd. All rights reserved.

Pyrolysis reactor and fluidized bed combustion chamber

DOEpatents

Green, Norman W.

1981-01-06

A solid carbonaceous material is pyrolyzed in a descending flow pyrolysis reactor in the presence of a particulate source of heat to yield a particulate carbon containing solid residue. The particulate source of heat is obtained by educting with a gaseous source of oxygen the particulate carbon containing solid residue from a fluidized bed into a first combustion zone coupled to a second combustion zone. A source of oxygen is introduced into the second combustion zone to oxidize carbon monoxide formed in the first combustion zone to heat the solid residue to the temperature of the particulate source of heat.

Hydrolysis of lactose by beta-glycosidase CelB from hyperthermophilic archaeon Pyrococcus furiosus: comparison of hollow-fiber membrane and packed-bed immobilized enzyme reactors for continuous processing of ultrahigh temperature-treated skim milk.

PubMed

Splechtna, Barbara; Petzelbauer, Inge; Kuhn, Bernhard; Kulbe, Klaus D; Nidetzky, Bernd

2002-01-01

Recombinant beta-glycosidase CelB from the hyperthermophilic archaeon Pyrococcusfuriosus was produced through expression of the plasmid-encoded gene in Escherichia coli. Bioreactor cultivations of E. coli in the presence of the inductor isopropyl-1-thio-beta-D-galactoside (0.1 mM) gave approx 100,000 U of enzyme activity/L of culture medium after 8 h of growth. A technical-grade enzyme for the hydrolysis of lactose was prepared by precipitating the mesophilic protein at 80 degrees C. A hollow-fiber membrane reactor was developed, and its performance during continuous processing of ultrahigh temperature-treated (UHT) skim milk at 70 degrees C was analyzed regarding long-term stability, productivity, and diffusional limitation thereof. CelB was covalently attached onto Eupergit C in yields of 80%, and a packed-bed immobilized enzyme reactor was used for the continuous hydrolysis of lactose in UHT skim milk at 70 degrees C. The packed-bed reactor was approximately 10-fold more stable and gave about the same productivity at 80% substrate conversion as the hollow-fiber reactor at 60% substrate conversion. The marked difference in the stability of free and immobilized CelB seems to reflect mainly binding of the soluble enzyme to the membrane surface of the hollow-fiber module. Under these bound conditions, CelB is essentially inactive. CelB is essentially inactive. Microbial contamination of the reactors did not occur during reaction times of up to 39 d, given that UHT skim milk and not pasteurized skim milk was used as the substrate.

Process for the preparation of cumene

DOEpatents

Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

1991-01-01

Cumene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic by feeding propylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with propylene, thereby reacting substantially all of the propylene and recovering benzene as the principal overhead and cumene and diisopropyl benzene in the bottoms. The bottoms are fractionated, the cumene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diisopropyl benzene to cumene which is again separated and recovered.

Process for the preparation of cumene

DOEpatents

Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

1991-10-08

Cumene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50 C to 500 C, using as the catalyst a molecular sieve characterized as acidic by feeding propylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with propylene, thereby reacting substantially all of the propylene and recovering benzene as the principal overhead and cumene and diisopropyl benzene in the bottoms. The bottoms are fractionated, the cumene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diisopropyl benzene to cumene which is again separated and recovered. 2 figures.

Process for the preparation of ethyl benzene

DOEpatents

Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

1995-12-19

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50 C to 300 C, using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered. 2 figs.

Process for the preparation of ethyl benzene

DOEpatents

Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

1995-01-01

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50.degree. C. to 300.degree. C., using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered.

Prediction of moving bed biofilm reactor (MBBR) performance for the treatment of aniline using artificial neural networks (ANN).

PubMed

Delnavaz, M; Ayati, B; Ganjidoust, H

2010-07-15

In this study, the results of 1-year efficiency forecasting using artificial neural networks (ANN) models of a moving bed biofilm reactor (MBBR) for a toxic and hard biodegradable aniline removal were investigated. The reactor was operated in an aerobic batch and continuous condition with 50% by volume which was filled with light expanded clay aggregate (LECA) as carrier. Efficiency evaluation of the reactors was obtained at different retention time (RT) of 8, 24, 48 and 72 h with an influent COD from 100 to 4000 mg/L. Exploratory data analysis was used to detect relationships between the data and dependent evaluated one. The appropriate architecture of the neural network models was determined using several steps of training and testing of the models. The ANN-based models were found to provide an efficient and a robust tool in predicting MBBR performance for treating aromatic amine compounds. 2010 Elsevier B.V. All rights reserved.

Leachate flush strategies for managing volatile fatty acids accumulation in leach-bed reactors.

PubMed

Riggio, S; Torrijos, M; Vives, G; Esposito, G; van Hullebusch, E D; Steyer, J P; Escudié, R

2017-05-01

In anaerobic leach-bed reactors (LBRs) co-digesting an easily- and a slowly-degradable substrate, the importance of the leachate flush both on extracting volatile fatty acids (VFAs) at the beginning of newly-started batches and on their consumption in mature reactors was tested. Regarding VFA extraction three leachate flush-rate conditions were studied: 0.5, 1 and 2Lkg -1 TSd -1 . Results showed that increasing the leachate flush-rate during the acidification phase is essential to increase degradation kinetics. After this initial phase, leachate injection is less important and the flush-rate could be reduced. The injection in mature reactors of leachate with an acetic acid concentration of 5 or 10gL -1 showed that for an optimized VFA consumption in LBRs, VFAs should be provided straight after the methane production peak in order to profit from a higher methanogenic activity, and every 6-7h to maintain a high biogas production rate. Copyright © 2017 Elsevier Ltd. All rights reserved.

The characteristics of extracellular polymeric substances and soluble microbial products in moving bed biofilm reactor-membrane bioreactor.

PubMed

Duan, Liang; Jiang, Wei; Song, Yonghui; Xia, Siqing; Hermanowicz, Slawomir W

2013-11-01

The characteristics of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in conventional membrane bioreactor (MBR) and in moving bed biofilm reactor-membrane bioreactors (MBBR-MBR) were investigated in long-term (170 days) experiments. The results showed that all reactors had high removal efficiency of ammonium and COD, despite very different fouling conditions. The MBBR-MBR with media fill ratio of 26.7% had much lower total membrane resistance and no obvious fouling were detected during the whole operation. In contrast, MBR and MBBR-MBR with lower and higher media fill experienced more significant fouling. Low fouling at optimum fill ratio may be due to the higher percentage of small molecular size (<1 kDa) and lower percentage of large molecular size (>100 kDa) of EPS and SMP in the reactor. The composition of EPS and SMP affected fouling due to different O-H bonds in hydroxyl functional groups, and less polysaccharides and lipids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Simultaneous organic nitrogen and sulfate removal in an anaerobic GAC fluidised bed reactor.

PubMed

Fdz-Polanco, F; Fdz-Polanco, M; Fernandez, N; Urueña, M A; García, P A; Villaverde, S

2001-01-01

A granular activated carbon (GAC) anaerobic fluidised bed reactor treating vinasse from an ethanol distillery of sugar beet molasses was operated for 250 days under three different organic loading rates. The reactor showed good performance in terms of organic matter removal and methane production but an anomalous behaviour in terms of unusual high concentrations of molecular nitrogen and low concentration of hydrogen sulphide in the biogas. The analysis of the different nitrogenous and sulphur compounds and the mass balances of these species in the liquid and gas phases clearly indicated an uncommon evolution of nitrogen and sulphur in the reactor. Up to 55% of the TKN and up to 80% of the sulphur disappear in the liquid phase. This is the opposite to any previously reported results in the bibliography. The new postulated anaerobic process of ammonia and sulphate removal seems to follow the mechanism: SO4 = +2 NH4+-->S + N2 + 4H2O (delta G degree = -47.8 kJ/mol).

Kinetics study of palm oil hydrolysis using immobilized lipase Candida rugosa in packed bed reactor.

PubMed

Min, C S; Bhatia, S; Kamaruddin, A H

1999-01-01

Continuous hydrolysis of palm oil triglyceride in organic solvent using immobilized Candida rugosa on the Amberlite MB-1 as a source of immobilized lipase was studied in packed bed reactor. The enzymatic kinetics of hydrolysis reaction was studied by changing the substrate concentration, reaction temperature and residence time(tau) in the reactor. At 55 degrees C, the optimum water concentration was found to be 15 % weight per volume of solution (%w/v). The Michaelis-Menten kinetic model was used to obtain the reaction parameters, Km(app) and V max(app). The activation energies were found to be quite low indicating that the lipase-catalyzed process is controlled by diffusion of substrates. The Michaelis-Menten kinetic model was found to be suitable at low water concentration 10-15 %w/v of solution. At higher water concentration, substrate inhibition model was used for data analysis. Reactor operation was found to play an important role in the palm oil hydrolysis kinetic.

Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor

PubMed Central

Bertin, Lorenzo; Colao, Maria Chiara; Ruzzi, Maurizio; Marchetti, Leonardo; Fava, Fabio

2006-01-01

Background Olive mill wastewater (OMW) is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. Results The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl-1day-1 of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl-1day-1 of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter, enriched significantly in the biofilter throughout the treatment. Conclusion The silica-bead packed bed biofilm reactor developed and characterized in this study was able to significantly decontaminate anaerobically digested OMWs. Therefore, the application of an integrated anaerobic-aerobic process resulted in an improved system for valorization and decontamination of OMWs. PMID:16595023

Numerical modelling of heat and mass transfer in adsorption solar reactor of ammonia on active carbon

NASA Astrophysics Data System (ADS)

Aroudam, El. H.

In this paper, we present a modelling of the performance of a reactor of a solar cooling machine based carbon-ammonia activated bed. Hence, for a solar radiation, measured in the Energetic Laboratory of the Faculty of Sciences in Tetouan (northern Morocco), the proposed model computes the temperature distribution, the pressure and the ammonia concentration within the activated carbon bed. The Dubinin-Radushkevich formula is used to compute the ammonia concentration distribution and the daily cycled mass necessary to produce a cooling effect for an ideal machine. The reactor is heated at a maximum temperature during the day and cool at the night. A numerical simulation is carried out employing the recorded solar radiation data measured locally and the daily ambient temperature for the typical clear days. Initially the reactor is at ambient temperature, evaporating pressure; Pev=Pst(Tev=0 ∘C) and maintained at uniform concentration. It is heated successively until the threshold temperature corresponding to the condensing pressure; Pcond=Pst(Tam) (saturation pressure at ambient temperature; in the condenser) and until a maximum temperature at a constant pressure; Pcond. The cooling of the reactor is characterised by a fall of temperature to the minimal values at night corresponding to the end of a daily cycle. We use the mass balance equations as well as energy equation to describe heat and mass transfer inside the medium of three phases. A numerical solution of the obtained non linear equations system based on the implicit finite difference method allows to know all parameters characteristic of the thermodynamic cycle and consider principally the daily evolution of temperature, ammonia concentration for divers positions inside the reactor. The tube diameter of the reactor shows the dependence of the optimum value on meteorological parameters for 1 m2 of collector surface.

FIXED-BED HYDROGENATION OF ORGANIC COMPOUNDS IN SUPERCRITICAL CARBON DIOXIDE. (R826034)

EPA Science Inventory

Abstract

The Pd/C hydrogenation of cyclohexene to cyclohexane was performed in a continuous fixed-bed reactor employing CO₂ to solubilize the reaction mixture in a single supercritical (sc) phase surrounding the solid catalyst. Employing an equimolar feed of...

Thin-film fixed-bed reactor for solar photocatalytic inactivation of Aeromonas hydrophila: influence of water quality

PubMed Central

2012-01-01

Background Controlling fish disease is one of the major concerns in contemporary aquaculture. The use of antibiotics or chemical disinfection cannot provide a healthy aquaculture system without residual effects. Water quality is also important in determining the success or failure of fish production. Several solar photocatalytic reactors have been used to treat drinking water or waste water without leaving chemical residues. This study has investigated the impact of several key aspects of water quality on the inactivation of the pathogenic bacterium Aeromonas hydrophila using a pilot-scale thin-film fixed-bed reactor (TFFBR) system. Results The level of inactivation of Aeromonas hydrophila ATCC 35654 was determined using a TFFBR with a photocatalytic area of 0.47 m2 under the influence of various water quality variables (pH, conductivity, turbidity and colour) under high solar irradiance conditions (980–1100 W m-2), at a flow rate of 4.8 L h-1 through the reactor. Bacterial enumeration were obtained through conventional plate count using trypticase soy agar media, cultured in conventional aerobic conditions to detect healthy cells and under ROS-neutralised conditions to detect both healthy and sub-lethally injured (oxygen-sensitive) cells. The results showed that turbidity has a major influence on solar photocatalytic inactivation of A. hydrophila. Humic acids appear to decrease TiO2 effectiveness under full sunlight and reduce microbial inactivation. pH in the range 7–9 and salinity both have no major effect on the extent of photoinactivation or sub-lethal injury. Conclusions This study demonstrates the effectiveness of the TFFBR in the inactivation of Aeromonas hydrophila under the influence of several water quality variables at high solar irradiance, providing an opportunity for the application of solar photocatalysis in aquaculture systems, as long as turbidity remains low. PMID:23194331

Biofiltration of odors, toxics and volatile organic compounds from publicly owned treatment works

DOE Office of Scientific and Technical Information (OSTI.GOV)

Webster, T.S.; Devinny, J.S.; Torres, E.M.

1996-12-31

Increasing federal and state regulation has made it necessary to apply air pollution control measures at publicly owned treatment works (POTWs). Traditional control technologies may not be suitable for treating the low and variable contaminant concentrations often found in POTW off-gases. An alternative control technology, biofiltration, was studied. An experiment using bench- and pilot-scale reactors established optimal operating conditions for a full-scale conceptual design. The waste airstream contained ppmv levels of hydrogen sulfide and ppbv levels of specific volatile organic compounds (VOCs). Granular activated carbon (GAC) and yard waste compost (YWG) were tested as possible biofilter media with and withoutmore » pH control. The 16-month field study bench reactors achieved 99% removal of hydrogen sulfide, 53 to 98% removal of aromatic hydrocarbons, 37 to 95% removal of aldehydes and ketones, and 0 to 85% removal of chlorinated compounds. The GAC and YWC pilot reactors removed more than 80% and 65% of the total VOCs at 17 second and 70 second empty bed retention times, respectively. The YWC reactors performed poorly at empty bed retention times of 30 and 45 seconds, removing less than 40% of total VOCs. Declining pH had little negative effect on contaminant removal, suggesting costly control measures may not be necessary. Biofiltration appears to be a feasible alternative to traditional control technologies in treating off-gases from POTWs. 13 refs., 3 figs., 4 tabs.« less

Technology development for cobalt F-T catalysts. Quarterly technical progress report number 10, January 1--March 31, 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singleton, A.H.

1995-06-28

The goal of this project is the development of a commercially-viable, cobalt-based Fischer-Tropsch (F-T) catalyst for use in a slurry bubble column reactor. The major objectives of this work are (1) to develop a cobalt-based F-T catalyst with low (< 5%) methane selectivity, (2) to develop a cobalt-based F-T catalyst with water-gas shift activity, and (3) to combine both these improvements into one catalyst. The project consists of five major tasks: catalyst development; catalyst testing; catalyst reproducibility tests; catalyst aging tests; and preliminary design and cost estimate for a demonstrate scale catalyst production facility. Technical accomplishments during this reporting periodmore » include the following. It appears that the higher activity obtained for the catalysts prepared using an organic solution and reduced directly without prior calcination was the result of higher dispersions obtained under such pretreatment. A Ru-promoted Co catalyst on alumina with 30% Co loading exhibited a 4-fold increase in dispersion and a 2-fold increase in activity in the fixed-bed reactor from that obtained with the non-promoted catalyst. Several reactor runs have again focused on pushing conversion to higher levels. The maximum conversion obtained has been 49.7% with 26g catalyst. Further investigations of the effect of reaction temperature on the performance of Co catalysts during F-T synthesis were started using a low activity catalyst and one of the most active catalysts. The three 1 kg catalyst batches prepared by Calsicat for the reproducibility and aging studies were tested in both the fixed-bed and slurry bubble column reactors under the standard reaction conditions. The effects of adding various promoters to some cobalt catalysts have also been addressed. Results are presented and discussed.« less

Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor

PubMed Central

Azizi, Shohreh; Kamika, Ilunga; Tekere, Memory

2016-01-01

For the effective application of a modified packed bed biofilm reactor (PBBR) in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni) was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT) of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l) concentrations of combined heavy metals at an optimum HRT condition (2 hours), while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD) of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l), is capable of removing the industrial contamination in wastewater. PMID:27186636

Biomass conversion to produce hydrocarbon liquid fuel via hot-vapor filtered fast pyrolysis and catalytic hydrotreating

DOE PAGES

Wang, Huamin; Elliott, Douglas C.; French, Richard J.; ...

2016-12-25

Lignocellulosic biomass conversion to produce biofuels has received significant attention because of the quest for a replacement for fossil fuels. Among the various thermochemical and biochemical routes, fast pyrolysis followed by catalytic hydrotreating is considered to be a promising near-term opportunity. This paper reports on experimental methods used 1) at the National Renewable Energy Laboratory (NREL) for fast pyrolysis of lignocellulosic biomass to produce bio-oils in a fluidized-bed reactor and 2) at Pacific Northwest National Laboratory (PNNL) for catalytic hydrotreating of bio-oils in a two-stage, fixed-bed, continuous-flow catalytic reactor. The configurations of the reactor systems, the operating procedures, and themore » processing and analysis of feedstocks, bio-oils, and biofuels are described in detail in this paper. We also demonstrate hot-vapor filtration during fast pyrolysis to remove fine char particles and inorganic contaminants from bio-oil. Representative results showed successful conversion of biomass feedstocks to fuel-range hydrocarbon biofuels and, specifically, the effect of hot-vapor filtration on bio-oil production and upgrading. As a result, the protocols provided in this report could help to generate rigorous and reliable data for biomass pyrolysis and bio-oil hydrotreating research.« less

Biomass conversion to produce hydrocarbon liquid fuel via hot-vapor filtered fast pyrolysis and catalytic hydrotreating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Huamin; Elliott, Douglas C.; French, Richard J.

Lignocellulosic biomass conversion to produce biofuels has received significant attention because of the quest for a replacement for fossil fuels. Among the various thermochemical and biochemical routes, fast pyrolysis followed by catalytic hydrotreating is considered to be a promising near-term opportunity. This paper reports on experimental methods used 1) at the National Renewable Energy Laboratory (NREL) for fast pyrolysis of lignocellulosic biomass to produce bio-oils in a fluidized-bed reactor and 2) at Pacific Northwest National Laboratory (PNNL) for catalytic hydrotreating of bio-oils in a two-stage, fixed-bed, continuous-flow catalytic reactor. The configurations of the reactor systems, the operating procedures, and themore » processing and analysis of feedstocks, bio-oils, and biofuels are described in detail in this paper. We also demonstrate hot-vapor filtration during fast pyrolysis to remove fine char particles and inorganic contaminants from bio-oil. Representative results showed successful conversion of biomass feedstocks to fuel-range hydrocarbon biofuels and, specifically, the effect of hot-vapor filtration on bio-oil production and upgrading. As a result, the protocols provided in this report could help to generate rigorous and reliable data for biomass pyrolysis and bio-oil hydrotreating research.« less

Transport Corrections in Nodal Diffusion Codes for HTR Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abderrafi M. Ougouag; Frederick N. Gleicher

2010-08-01

The cores and reflectors of High Temperature Reactors (HTRs) of the Next Generation Nuclear Plant (NGNP) type are dominantly diffusive media from the point of view of behavior of the neutrons and their migration between the various structures of the reactor. This means that neutron diffusion theory is sufficient for modeling most features of such reactors and transport theory may not be needed for most applications. Of course, the above statement assumes the availability of homogenized diffusion theory data. The statement is true for most situations but not all. Two features of NGNP-type HTRs require that the diffusion theory-based solutionmore » be corrected for local transport effects. These two cases are the treatment of burnable poisons (BP) in the case of the prismatic block reactors and, for both pebble bed reactor (PBR) and prismatic block reactor (PMR) designs, that of control rods (CR) embedded in non-multiplying regions near the interface between fueled zones and said non-multiplying zones. The need for transport correction arises because diffusion theory-based solutions appear not to provide sufficient fidelity in these situations.« less

Laundry greywater treatment using a fluidized bed reactor: a proposed model based on greywater biodegradation and residence time distribution approach.

PubMed

David, Pierre-luc; Bulteau, Gaëlle; Humeau, Philippe; Gérente, Claire; Andrès, Yves

2013-01-01

The increasing demand for water and the decrease in global water resources require research into alternative solutions to preserve them. The present study deals with the optimization of a treatment process, i.e. an aerobic fluidized bed reactor and the modelling of the degradation that takes place within it. The methodology employed is based on the hydrodynamics of the treatment process linked to the biodegradation kinetics of greywater coming from a washing machine. The residence time distribution (RTD) approach is selected for the hydrodynamic study. Biodegradation kinetics are quantified by respirometry and dissolved organic carbon (DOC) analysis on several mass quantities of colonized particles. RTD determinations show that there are no dysfunctions in the fluidized bed. Its hydrodynamic behaviour is similar to the one of a continuous stirred-tank reactor. A first-order reaction is obtained from the DOC biodegradation study. A model describing the degradation that takes place into the reactor is proposed, and from a sensitive study, the influence of the operating conditions on DOC biodegradation is defined. The theoretical results calculated from the first-order equation C(t) = 0.593 x C(0) x e(-kt) are compared with the experimental results and validated by a Student test. The value of the kinetic constant k is 0.011 h(-1) in the presence of a biomass carrier. The results highlight that it is possible to design a reactor in order to obtain a carbon content lower than 15 mg C L(-1) when the characteristics of raw greywater are known.

Beryllium for fusion application - recent results

NASA Astrophysics Data System (ADS)

Khomutov, A.; Barabash, V.; Chakin, V.; Chernov, V.; Davydov, D.; Gorokhov, V.; Kawamura, H.; Kolbasov, B.; Kupriyanov, I.; Longhurst, G.; Scaffidi-Argentina, F.; Shestakov, V.

2002-12-01

The main issues for the application of beryllium in fusion reactors are analyzed taking into account the latest results since the ICFRM-9 (Colorado, USA, October 1999) and presented at 5th IEA Be Workshop (10-12 October 2001, Moscow Russia). Considerable progress has been made recently in understanding the problems connected with the selection of the beryllium grades for different applications, characterization of the beryllium at relevant operational conditions (irradiation effects, thermal fatigue, etc.), and development of required manufacturing technologies. The key remaining problems related to the application of beryllium as an armour in near-term fusion reactors (e.g. ITER) are discussed. The features of the application of beryllium and beryllides as a neutron multiplier in the breeder blanket for power reactors (e.g. DEMO) in pebble-bed form are described.

Exceptional arsenic (III,V) removal performance of highly porous, nanostructured ZrO2 spheres for fixed bed reactors and the full-scale system modeling.

PubMed

Cui, Hang; Su, Yu; Li, Qi; Gao, Shian; Shang, Jian Ku

2013-10-15

Highly porous, nanostructured zirconium oxide spheres were fabricated from ZrO2 nanoparticles with the assistance of agar powder to form spheres with size at millimeter level followed with a heat treatment at 450 °C to remove agar network, which provided a simple, low-cost, and safe process for the synthesis of ZrO2 spheres. These ZrO2 spheres had a dual-pore structure, in which interconnected macropores were beneficial for liquid transport and the mesopores could largely increase their surface area (about 98 m(2)/g) for effective contact with arsenic species in water. These ZrO2 spheres demonstrated an even better arsenic removal performance on both As(III) and As(V) than ZrO2 nanoparticles, and could be readily applied to commonly used fixed-bed adsorption reactors in the industry. A short bed adsorbent test was conducted to validate the calculated external mass transport coefficient and the pore diffusion coefficient. The performance of full-scale fixed bed systems with these ZrO2 spheres as the adsorber was estimated by the validated pore surface diffusion modeling. With the empty bed contact time (EBCT) at 10 min and the initial arsenic concentration at 30 ppb, the number of bed volumes that could be treated by these dry ZrO2 spheres reached ~255,000 BVs and ~271,000 BVs for As(III) and As(V), respectively, until the maximum contaminant level of 10 ppb was reached. These ZrO2 spheres are non-toxic, highly stable, and resistant to acid and alkali, have a high arsenic adsorption capacity, and could be easily adapted for various arsenic removal apparatus. Thus, these ZrO2 spheres may have a promising potential for their application in water treatment practice. Copyright © 2013 Elsevier Ltd. All rights reserved.

Strategies for the startup of methanogenic inverse fluidized-bed reactors using colonized particles.

PubMed

Alvarado-Lassman, A; Sandoval-Ramos, A; Flores-Altamirano, M G; Vallejo-Cantú, N A; Méndez-Contreras, J M

2010-05-01

One of the inconveniences in the startup of methanogenic inverse fluidized-bed reactors (IFBRs) is the long period required for biofilm formation and stabilization of the system. Previous researchers have preferred to start up in batch mode to shorten stabilization times. Much less work has been done with continuous-mode startup for the IFBR configuration of reactors. In this study, we prepared two IFBRs with similar characteristics to compare startup times for batch- and continuous-operation modes. The reactors were inoculated with a small quantity of colonized particles and run for a period of 3 months, to establish the optimal startup strategy using synthetic media as a substrate (glucose as a source of carbon). After the startup stage, the continuous- and batch-mode reactors removed more than 80% of the chemical oxygen demand (COD) in 51 and 60 days of operation, respectively; however, at the end of the experiments, the continuous-mode reactor had more biomass attached to the support media than the batch-mode reactor. Both reactors developed fully covered support media, but only the continuous-mode reactor had methane yields close to the theoretical value that is typical of stable reactors. Then, a combined startup strategy was proposed, with industrial wastewater as the substrate, using a sequence of batch cycles followed by continuous operation, which allows stable operation at an organic loading rate of 20 g COD/L x d in 15 days. Using a fraction of colonized support as an inoculum presents advantages, with respect to previously reported strategies.

Beneficial synergetic effect on gas production during co-pyrolysis of sewage sludge and biomass in a vacuum reactor.

PubMed

Zhang, Weijiang; Yuan, Chengyong; Xu, Jiao; Yang, Xiao

2015-05-01

A vacuum fixed bed reactor was used to pyrolyze sewage sludge, biomass (rice husk) and their blend under high temperature (900°C). Pyrolytic products were kept in the vacuum reactor during the whole pyrolysis process, guaranteeing a long contact time (more than 2h) for their interactions. Remarkable synergetic effect on gas production was observed. Gas yield of blend fuel was evidently higher than that of both parent fuels. The syngas (CO and H2) content and gas lower heating value (LHV) were obviously improved as well. It was highly possible that sewage sludge provided more CO2 and H2O during co-pyrolysis, promoting intense CO2-char and H2O-char gasification, which benefited the increase of gas yield and lower heating value. The beneficial synergetic effect, as a result, made this method a feasible one for gas production. Copyright © 2015. Published by Elsevier Ltd.

Effect of loading types on performance characteristics of a trickle-bed bioreactor and biofilter during styrene/acetone vapor biofiltration.

PubMed

Halecky, Martin; Paca, Jan; Kozliak, Evguenii; Jones, Kim

2016-07-02

A 2:1 (w/w) mixture of styrene (STY) and acetone (AC) was subjected to lab-scale biofiltration under varied loading in both a trickle bed reactor (TBR) and biofilter (BF) to investigate substrate interactions and determine the limits of biofiltration efficiency of typical binary air pollutant mixtures containing both hydrophobic and polar components. A comparison of the STY/AC mixture degradation in the TBR and BF revealed higher pollutant removal efficiencies and degradation rates in the TBR, with the pollutant concentrations increasing up to the overloading limit. The maximum styrene degradation rates were 12 and 8 gc m(-3) h(-1) for the TBR and BF, respectively. However, the order of performance switched in favor of the BF when the loading was conducted by increasing air flow rate while keeping the inlet styrene concentration (Cin) constant in contrast to loading by increasing Cin. This switch may be due to a drastic difference in the effective surface area between these two reactors, so the biofilter becomes the reactor of choice when the rate-limiting step switches from biochemical processes to mass transfer by changing the loading mode. The presence of acetone in the mixture decreased the efficiency of styrene degradation and its degradation rate at high loadings. When the overloading was lifted by lowering the pollutant inlet concentrations, short-term back-stripping of both substrates in both reactors into the outlet air was observed, with a subsequent gradual recovery taking several hours and days in the BF and TBR, respectively. Removal of excess biomass from the TBR significantly improved the reactor performance. Identification of the cultivable strains, which was performed on Day 763 of continuous operation, showed the presence of 7 G(-) bacteria, 2 G(+) bacteria and 4 fungi. Flies and larvae of Lycoriella nigripes survived half a year of the biofilter operation by feeding on the biofilm resulting in the maintenance of a nearly constant pressure drop.

Combustion of peanut and tamarind shells in a conical fluidized-bed combustor: a comparative study.

PubMed

Kuprianov, Vladimir I; Arromdee, Porametr

2013-07-01

Combustion of peanut and tamarind shells was studied in the conical fluidized-bed combustor using alumina sand as the bed material to prevent bed agglomeration. Morphological, thermogravimetric and kinetic characteristics were investigated to compare thermal and combustion reactivity between the biomass fuels. The thermogravimetric kinetics of the biomasses was fitted using the Coats-Redfern method. Experimental tests on the combustor were performed at 60 and 45 kg/h fuel feed rates, with excess air within 20-80%. Temperature and gas concentrations were measured along radial and axial directions in the reactor and at stack. The axial temperature and gas concentration profiles inside the combustor exhibited sensible effects of fuel properties and operating conditions on combustion and emission performance. High (≈ 99%) combustion efficiency and acceptable levels of CO, CxHy, and NO emissions are achievable when firing peanut shells at excess air of about 40%, whereas 60% is more preferable for burning tamarind shells. Copyright © 2013 Elsevier Ltd. All rights reserved.

Attrition of coal ash particles in a fluidized-bed reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomeczek, J.; Mocek, P.

2007-05-15

Experimental data of ash-particles attrition in a fluidized bed is presented, and also the results of modeling. Five sizes of ash particles (1.02-1.25; 1.25-1.6; 1.6-2.0; 2.0-5.0; 5.0-10.0 mm) produced in an industrial CFB boiler were examined. A new model of mechanical attrition has been proposed which incorporates new parameters: the shape factor of particles and the ratio of the bed height to bed diameter, strongly influencing the rate of bed mass loss. The model describes very well experimental data for coal-ash particles attrition. The attrition-rate coefficient for ash particles was evaluated.

Lifelong Learning: The Value of an Industrial Internship for a Graduate Student Education

ERIC Educational Resources Information Center

Honda, Gregory S.; Pazmino, Jorge H.; Hickman, Daniel A.; Varma, Arvind

2015-01-01

A chemical engineering PhD student from Purdue University completed an internship at The Dow Chemical Company, evaluating the effect of scale on the hydrodynamics of a trickle bed reactor. A unique aspect of this work was that it arose from an ongoing collaboration, so that the project was within the scope of the graduate student's thesis. This…

Nitrification of an industrial wastewater in a moving-bed biofilm reactor: effect of salt concentration.

PubMed

Vendramel, Simone; Dezotti, Marcia; Sant'Anna, Geraldo L

2011-01-01

Nitrification of wastewaters from chemical industries can pose some challenges due to the presence of inhibitory compounds. Some wastewaters, besides their organic complexity present variable levels of salt concentration. In order to investigate the effect of salt (NaCl) content on the nitrification of a conventional biologically treated industrial wastewater, a bench scale moving-bed biofilm reactor was operated on a sequencing batch mode. The wastewater presenting a chloride content of 0.05 g l(-1) was supplemented with NaCl up to 12 g Cl(-) l(-1). The reactor operation cycle was: filling (5 min), aeration (12 or 24h), settling (5 min) and drawing (5 min). Each experimental run was conducted for 3 to 6 months to address problems related to the inherent wastewater variability and process stabilization. A PLC system assured automatic operation and control of the pertinent process variables. Data obtained from selected batch experiments were adjusted by a kinetic model, which considered ammonia, nitrite and nitrate variations. The average performance results indicated that nitrification efficiency was not influenced by chloride content in the range of 0.05 to 6 g Cl(-) l(-1) and remained around 90%. When the chloride content was 12 g Cl(-) l(-1), a significant drop in the nitrification efficiency was observed, even operating with a reaction period of 24 h. Also, a negative effect of the wastewater organic matter content on nitrification efficiency was observed, which was probably caused by growth of heterotrophs in detriment of autotrophs and nitrification inhibition by residual chemicals.

Acidogenic digestion of food waste in a thermophilic leach bed reactor: Effect of pH and leachate recirculation rate on hydrolysis and volatile fatty acid production.

PubMed

Hussain, Abid; Filiatrault, Mélissa; Guiot, Serge R

2017-12-01

The effect of pH control (4, 5, 6, 7) on volatile fatty acids (VFA) production from food waste was investigated in a leach bed reactor (LBR) operated at 50°C. Stabilisation of pH at 7 resulted in hydrolysis yield of 530g soluble chemical oxygen demand (sCOD)/kg total volatile solids (TVS) added and VFA yield of 247gCOD/kg TVS added, which were highest among all pH tested. Butyric acid dominated the VFA mix (49-54%) at pH of 7 and 6, while acetate composed the primary VFA (41-56%) at pH of 4 and 5. A metabolic shift towards lactic acid production was observed at pH of 5. Improving leachate recirculation rate further improved the hydrolysis and degradation efficiency by 10-16% and the acidification yield to 340gCOD/kgTVS added. The butyric acid concentration of 16.8g/L obtained at neutral pH conditions is among the highest reported in literature. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Impact of fine mesh sieve primary treatment on nitrogen removal in moving bed biofilm reactors.

PubMed

Rusten, B; Razafimanantsoa, V A; Andriamiarinjaka, M A; Otis, C L; Sahu, A K; Bilstad, T

2016-01-01

The purpose of this project was to investigate the effect of selective particle removal during primary treatment on nitrogen removal in moving bed biofilm reactors (MBBRs). Two small MBBR pilot plants were operated in parallel, where one train treated 2 mm screened municipal wastewater and the other train treated wastewater that had passed through a Salsnes Filter SF1000 rotating belt sieve (RBS) with a 33 µs sieve cloth. The SF1000 was operated without a filter mat on the belt. The tests confirmed that, for the wastewater characteristics at the test plant, Salsnes Filter primary treatment with a 33 µs RBS and no filter mat produced a primary effluent that was close to optimum. Removal of organic matter with the 33 µs sieve had no negative effect on the denitrification process. Nitrification rates improved by 10-15% in the train with 33 µs RBS primary treatment. Mass balance calculations showed that without RBS primary treatment, the oxygen demand in the biological system was 36% higher. Other studies have shown that the sludge produced by RBS primary treatment is beneficial for biogas production and will also significantly improve sludge dewatering of the combined primary and biological sludge.

Effects of using two- versus three-dimensional computational modeling of fluidized beds Part I, hydrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Nan; Battaglia, Francine; Pannala, Sreekanth

2008-01-01

Simulations of fluidized beds are performed to study and determine the effect on the use of coordinate systems and geometrical configurations to model fluidized bed reactors. Computational fluid dynamics is employed for an Eulerian-Eulerian model, which represents each phase as an interspersed continuum. The transport equation for granular temperature is solved and a hyperbolic tangent function is used to provide a smooth transition between the plastic and viscous regimes for the solid phase. The aim of the present work is to show the range of validity for employing simulations based on a 2D Cartesian coordinate system to approximate both cylindricalmore » and rectangular fluidized beds. Three different fluidization regimes, bubbling, slugging and turbulent regimes, are investigated and the results of 2D and 3D simulations are presented for both cylindrical and rectangular domains. The results demonstrate that a 2D Cartesian system can be used to successfully simulate and predict a bubbling regime. However, caution must be exercised when using 2D Cartesian coordinates for other fluidized regimes. A budget analysis that explains all the differences in detail is presented in Part II [N. Xie, F. Battaglia, S. Pannala, Effects of Using Two-Versus Three-Dimensional Computational Modeling of Fluidized Beds: Part II, budget analysis, 182 (1) (2007) 14] to complement the hydrodynamic theory of this paper.« less

Advanced CO2 Removal and Reduction System

NASA Technical Reports Server (NTRS)

Alptekin, Gokhan; Dubovik, Margarita; Copeland, Robert J.

2011-01-01

An advanced system for removing CO2 and H2O from cabin air, reducing the CO2, and returning the resulting O2 to the air is less massive than is a prior system that includes two assemblies . one for removal and one for reduction. Also, in this system, unlike in the prior system, there is no need to compress and temporarily store CO2. In this present system, removal and reduction take place within a single assembly, wherein removal is effected by use of an alkali sorbent and reduction is effected using a supply of H2 and Ru catalyst, by means of the Sabatier reaction, which is CO2 + 4H2 CH4 + O2. The assembly contains two fixed-bed reactors operating in alternation: At first, air is blown through the first bed, which absorbs CO2 and H2O. Once the first bed is saturated with CO2 and H2O, the flow of air is diverted through the second bed and the first bed is regenerated by supplying it with H2 for the Sabatier reaction. Initially, the H2 is heated to provide heat for the regeneration reaction, which is endothermic. In the later stages of regeneration, the Sabatier reaction, which is exothermic, supplies the heat for regeneration.

ENGINEERING APPLICATIONS OF ANALOG COMPUTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryant, L.T.; Janicke, M.J.; Just, L.C.

1961-02-01

Six examples are given of the application of analog computers in the fields of reactor engineering, heat transfer, and dynamics: deceleration of a reactor control rod by dashpot, pressure variations through a packed bed, reactor kinetics over many decades with thermal feedback (simulation of a TREAT transient), vibrating system with two degrees of freedom, temperature distribution in a radiating fin, and temperature distribution in an irfinite slab with variable thermal properties. (D.L.C.)

Modeling integrated fixed-film activated sludge and moving-bed biofilm reactor systems II: evaluation.

PubMed

Boltz, Joshua P; Johnson, Bruce R; Daigger, Glen T; Sandino, Julian; Elenter, Deborah

2009-06-01

A steady-state model presented by Boltz, Johnson, Daigger, and Sandino (2009) describing integrated fixed-film activated sludge (IFAS) and moving-bed biofilm reactor (MBBR) systems has been demonstrated to simulate, with reasonable accuracy, four wastewater treatment configurations with published operational data. Conditions simulated include combined carbon oxidation and nitrification (both IFAS and MBBR), tertiary nitrification MBBR, and post denitrification IFAS with methanol addition as the external carbon source. Simulation results illustrate that the IFAS/MBBR model is sufficiently accurate for describing ammonia-nitrogen reduction, nitrate/nitrite-nitrogen reduction and production, biofilm and suspended biomass distribution, and sludge production.

Israeli co-retorting of coal and oil shale would break even at 22/barrel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Work is being carried out at the Hebrew University of Jerusalem on co-retorting of coal and oil shale. The work is funded under a cooperative agreement with the US Department of Energy. The project is exploring the conversion of US eastern high-sulfur bituminous coal in a split-stage, fluidized-bed reactor. Pyrolysis occurs in the first stage and char combustion in the second stage. These data for coal will be compared with similar data from the same reactor fueled by high-sulfur eastern US oil shale and Israeli oil shales. The project includes research at three major levels: pyrolysis in lab-scale fluidized-bed reactor;more » retorting in split-stage, fluidized-bed bench-scale process (1/4 tpd); and scale-up, preparation of full-size flowchart, and economic evaluation. In the past year's research, a preliminary economic evaluation was completed for a scaled-up process using a feed of high-sulfur coal and carbonate-containing Israeli oil shale. A full-scale plant in Israel was estimated to break even at an equivalent crude oil price of $150/ton ($22/barrel).« less

Improved gas tagging and cover gas combination for nuclear reactor

DOEpatents

Gross, K.C.; Laug, M.T.

1983-09-26

The invention discloses the use of stable isotopes of neon and argon, sealed as tags in different cladding nuclear fuel elements to be used in a liquid metal fast breeder reactor. Cladding failure allows fission gases and these tag isotopes to escape and to combine with the cover gas. The isotopes are Ne/sup 20/, Ne/sup 21/ and Ne/sup 22/ and Ar/sup 36/, Ar/sup 38/ and Ar/sup 40/, and the cover gas is He. Serially connected cryogenically operated charcoal beds are used to clean the cover gas and to separate out the tags. The first or cover gas cleanup bed is held between 0 and -25/sup 0/C to remove the fission gases from the cover gas and tags, and the second or tag recovery system bed between -170 and -185/sup 0/C to isolate the tags from the cover gas. Spectrometric analysis is used to identify the specific tags that are recovered, and thus the specific leaking fuel element. By cataloging the fuel element tags to the location of the fuel elements in the reactor, the location of the leaking fuel element can then be determined.

New reactor for production of tungsten disulfide hollow onion-like (inorganic fullerene-like) nanoparticles

NASA Astrophysics Data System (ADS)

Feldman, Y.; Zak, A.; Popovitz-Biro, R.; Tenne, R.

2000-10-01

MS 2 (M=Mo, W) hollow onion-like nanoparticles were the first inorganic fullerene-like ( IF) materials, found in 1992. Understanding of the IF-MS 2 growth mechanism in 1996 enabled us to build a rather simple reactor, which produced about 0.4 g per batch, of an almost pure IF-WS 2 powder. Soon after, it was found that the new powder showed better tribological properties compared with the regular MS 2 (M=Mo, W) powder, which is a well-known solid lubricant. The present work shows a new synthetic approach, which allows for a scale-up of IF-WS 2 production by more than two orders of magnitude. The falling-bed and, especially, fluidized-bed methods, which are presented here, pave the way for an almost ideal growth condition of the IF synthesis from an oxide precursor. As a result, the presently produced IF has a more uniform (spherical) shape and can grow to a larger size (up to 0.5 μm). It is expected that the relatively spherical IF-WS 2 nanoparticles, which are produced by the falling (fluidized) bed reactor, will exhibit superior tribological properties, than reported before.

Low cost silicon solar array project silicon materials task: Establishment of the feasibility of a process capable of low-cost, high volume production of silane (step 1) and the pyrolysis of silane to semiconductor-grade silicon (step 2)

NASA Technical Reports Server (NTRS)

Breneman, W. C.; Farrier, E. G.; Rexer, J.

1977-01-01

Extended operation of a small process-development unit routinely produced high quality silane in 97+% yield from dichlorosilane. The production rate was consistent with design loadings for the fractionating column and for the redistribution reactor. A glass fluid-bed reactor was constructed for room temperature operation. The behavior of a bed of silcon particles was observed as a function of various feedstocks, component configurations, and operating conditions. For operating modes other than spouting, the bed behaved in an erratic and unstable manner. A method was developed for casting molten silicon powder into crack-free solid pellets for process evaluation. The silicon powder was melted and cast into thin walled quartz tubes that sacrificially broke on cooling.

Experimental investigation of bubbling in particle beds with high solid holdup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Songbai; Hirahara, Daisuke; Tanaka, Youhei

2011-02-15

A series of experiments on bubbling behavior in particle beds was performed to clarify three-phase flow dynamics in debris beds formed after core-disruptive accident (CDA) in sodium-cooled fast breeder reactors (FBRs). Although in the past, several experiments have been performed in packed beds to investigate flow patterns, most of these were under comparatively higher gas flow rate, which may be not expected during an early sodium boiling period in debris beds. The current experiments were conducted under two dimensional (2D) and three dimensional (3D) conditions separately, in which water was used as liquid phase, and bubbles were generated by injectingmore » nitrogen gas from the bottom of the viewing tank. Various particle-bed parameters were varied, including particle-bed height (from 30 mm to 200 mm), particle diameter (from 0.4 mm to 6 mm) and particle type (beads made of acrylic, glass, alumina and zirconia). Under these experimental conditions, three kinds of bubbling behavior were observed for the first time using digital image analysis methods that were further verified by quantitative detailed analysis of bubbling properties including surface bubbling frequency and surface bubble size under both 2D and 3D conditions. This investigation, which hopefully provides fundamental data for a better understanding and an improved estimation of CDAs in FBRs, is expected to benefit future analysis and verification of computer models developed in advanced fast reactor safety analysis codes. (author)« less

Carrier effects on tertiary nitrifying moving bed biofilm reactor: An examination of performance, biofilm and biologically produced solids.

PubMed

Forrest, Daina; Delatolla, Robert; Kennedy, Kevin

2016-01-01

Increasingly stricter ammonia and nitrogen release regulations with respect to wastewater effluents are creating a need for tertiary treatment systems. The moving bed biofilm reactor (MBBR) is being considered as an upgrade option for an increasing number of wastewater treatment facilities due to its small footprint and ease of operation. Despite the MBBRs creation as a system to remove nitrogen, recent research on MBBR systems showing that the system's performance is directly related to carrier surface area and is irrespective of carrier shape and type has been performed exclusively on chemical oxygen demand (COD) removal systems. Furthermore, the influence of carrier type on the solids produced by MBBR systems has also been exclusively studied for COD removal systems. This work investigates the effects of three specific carrier types on ammonia removal rates, biofilm morphology, along with solids production and settleability of tertiary nitrifying MBBR systems. The study concludes that carrier type has no significant effect on tertiary nitrifying MBBR system performance under steady, moderate loading conditions. The research does however highlight the propensity of greater surface area to volume carriers to become clogged under high loading conditions and that the high surface area carriers investigated in this study required longer adjustment periods to changes in loading after becoming clogged.

CFD modeling of space-time evolution of fast pyrolysis products in a bench-scale fluidized-bed reactor

USDA-ARS?s Scientific Manuscript database

A model for the evolution of pyrolysis products in a fluidized bed has been developed. In this study the unsteady constitutive transport equations for inert gas flow and decomposition kinetics were modeled using the commercial computational fluid dynamics (CFD) software FLUENT-12. The model system d...

JPL in-house fluidized bed reactor research

NASA Technical Reports Server (NTRS)

Rohatgi, N. K.

1985-01-01

The progress in the in-house program on the silane fluidized-bed system is reported. A seed-particle cleaning procedure was developed to obtain material purity near the level required to produce a semiconductor-grade product. The liner-seal design was consistently proven to withstand heating/cooling cycles in all of the experimental runs.

Pressurized reactor system and a method of operating the same

DOEpatents

Isaksson, J.M.

1996-06-18

A method and apparatus are provided for operating a pressurized reactor system in order to precisely control the temperature within a pressure vessel in order to minimize condensation of corrosive materials from gases on the surfaces of the pressure vessel or contained circulating fluidized bed reactor, and to prevent the temperature of the components from reaching a detrimentally high level, while at the same time allowing quick heating of the pressure vessel interior volume during start-up. Super-atmospheric pressure gas is introduced from the first conduit into the fluidized bed reactor and heat derived reactions such as combustion and gasification are maintained in the reactor. Gas is exhausted from the reactor and pressure vessel through a second conduit. Gas is circulated from one part of the inside volume to another to control the temperature of the inside volume, such as by passing the gas through an exterior conduit which has a heat exchanger, control valve, blower and compressor associated therewith, or by causing natural convection flow of circulating gas within one or more generally vertically extending gas passages entirely within the pressure vessel (and containing heat exchangers, flow rate control valves, or the like therein). Preferably, inert gas is provided as a circulating gas, and the inert gas may also be used in emergency shut-down situations. In emergency shut-down reaction gas being supplied to the reactor is cut off, while inert gas from the interior gas volume of the pressure vessel is introduced into the reactor. 2 figs.

Pressurized reactor system and a method of operating the same

DOEpatents

Isaksson, Juhani M.

1996-01-01

A method and apparatus are provided for operating a pressurized reactor system in order to precisely control the temperature within a pressure vessel in order to minimize condensation of corrosive materials from gases on the surfaces of the pressure vessel or contained circulating fluidized bed reactor, and to prevent the temperature of the components from reaching a detrimentally high level, while at the same time allowing quick heating of the pressure vessel interior volume during start-up. Superatmospheric pressure gas is introduced from the first conduit into the fluidized bed reactor and heat derived reactions such as combustion and gassification are maintained in the reactor. Gas is exhausted from the reactor and pressure vessel through a second conduit. Gas is circulated from one part of the inside volume to another to control the temperature of the inside volume, such as by passing the gas through an exterior conduit which has a heat exchanger, control valve, blower and compressor associated therewith, or by causing natural convection flow of circulating gas within one or more generally vertically extending gas passages entirely within the pressure vessel (and containing heat exchangers, flow rate control valves, or the like therein). Preferably, inert gas is provided as a circulating gas, and the inert gas may also be used in emergency shut-down situations. In emergency shut-down reaction gas being supplied to the reactor is cut off, while inert gas from the interior gas volume of the pressure vessel is introduced into the reactor.

Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Rui, E-mail: Sunsr@hit.edu.cn; Ismail, Tamer M., E-mail: temoil@aucegypt.edu; Ren, Xiaohan

Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on themore » combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW.« less

Efficient preparation of enantiopure D-phenylalanine through asymmetric resolution using immobilized phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1 in a recirculating packed-bed reactor.

PubMed

Zhu, Longbao; Zhou, Li; Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (eeD) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (eeD>99%) in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.

Efficient Preparation of Enantiopure D-Phenylalanine through Asymmetric Resolution Using Immobilized Phenylalanine Ammonia-Lyase from Rhodotorula glutinis JN-1 in a Recirculating Packed-Bed Reactor

PubMed Central

Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h−1 and 0.32 g L−1 h−1, respectively. The optical purity (ee D) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (ee D>99%) in the scaled-up reactor reached 7.2 g L−1 h−1. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine. PMID:25268937

Silicon production in a fluidized bed reactor

NASA Technical Reports Server (NTRS)

Rohatgi, N. K.

1986-01-01

Part of the development effort of the JPL in-house technology involved in the Flat-Plate Solar Array (FSA) Project was the investigation of a low-cost process to produce semiconductor-grade silicon for terrestrial photovoltaic cell applications. The process selected was based on pyrolysis of silane in a fluidized-bed reactor (FBR). Following initial investigations involving 1- and 2-in. diameter reactors, a 6-in. diameter, engineering-scale FBR was constructed to establish reactor performance, mechanism of silicon deposition, product morphology, and product purity. The overall mass balance for all experiments indicates that more than 90% of the total silicon fed into the reactor is deposited on silicon seed particles and the remaining 10% becomes elutriated fines. Silicon production rates were demonstrated of 1.5 kg/h at 30% silane concentration and 3.5 kg/h at 80% silane concentration. The mechanism of silicon deposition is described by a six-path process: heterogeneous deposition, homogeneous decomposition, coalescence, coagulation, scavenging, and heterogeneous growth on fines. The bulk of the growth silicon layer appears to be made up of small diameter particles. This product morphology lends support to the concept of the scavenging of homogeneously nucleated silicon.

Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

NASA Technical Reports Server (NTRS)

Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

1995-01-01

Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

II. Electrodeposition/removal of nickel in a spouted electrochemical reactor.

PubMed

Grimshaw, Pengpeng; Calo, Joseph M; Shirvanian, Pezhman A; Hradil, George

2011-08-17

An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well.

Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition

NASA Astrophysics Data System (ADS)

Duan, Chen-Long; Liu, Xiao; Shan, Bin; Chen, Rong

2015-07-01

A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas-solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al2O3 films on spherical SiO2 NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy.

Systems Based Approaches for Thermochemical Conversion of Biomass to Bioenergy and Bioproducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Steven

2016-07-11

Auburn’s Center for Bioenergy and Bioproducts conducts research on production of synthesis gas for use in power generation and the production of liquid fuels. The overall goal of our gasification research is to identify optimal processes for producing clean syngas to use in production of fuels and chemicals from underutilized agricultural and forest biomass feedstocks. This project focused on construction and commissioning of a bubbling-bed fluidized-bed gasifier and subsequent shakedown of the gasification and gas cleanup system. The result of this project is a fully commissioned gasification laboratory that is conducting testing on agricultural and forest biomass. Initial tests onmore » forest biomass have served as the foundation for follow-up studies on gasification under a more extensive range of temperatures, pressures, and oxidant conditions. The laboratory gasification system consists of a biomass storage tank capable of holding up to 6 tons of biomass; a biomass feeding system, with loss-in-weight metering system, capable of feeding biomass at pressures up to 650 psig; a bubbling-bed fluidized-bed gasification reactor capable of operating at pressures up to 650 psig and temperatures of 1500oF with biomass flowrates of 80 lb/hr and syngas production rates of 37 scfm; a warm-gas filtration system; fixed bed reactors for gas conditioning; and a final quench cooling system and activated carbon filtration system for gas conditioning prior to routing to Fischer-Tropsch reactors, or storage, or venting. This completed laboratory enables research to help develop economically feasible technologies for production of biomass-derived synthesis gases that will be used for clean, renewable power generation and for production of liquid transportation fuels. Moreover, this research program provides the infrastructure to educate the next generation of engineers and scientists needed to implement these technologies.« less

A fuzzy-logic-based controller for methane production in anaerobic fixed-film reactors.

PubMed

Robles, A; Latrille, E; Ruano, M V; Steyer, J P

2017-01-01

The main objective of this work was to develop a controller for biogas production in continuous anaerobic fixed-bed reactors, which used effluent total volatile fatty acids (VFA) concentration as control input in order to prevent process acidification at closed loop. To this aim, a fuzzy-logic-based control system was developed, tuned and validated in an anaerobic fixed-bed reactor at pilot scale that treated industrial winery wastewater. The proposed controller varied the flow rate of wastewater entering the system as a function of the gaseous outflow rate of methane and VFA concentration. Simulation results show that the proposed controller is capable to achieve great process stability even when operating at high VFA concentrations. Pilot results showed the potential of this control approach to maintain the process working properly under similar conditions to the ones expected at full-scale plants.

Application of a combined process of moving-bed biofilm reactor (MBBR) and chemical coagulation for dyeing wastewater treatment.

PubMed

Shin, D H; Shin, W S; Kim, Y H; Han, Myung Ho; Choi, S J

2006-01-01

A combined process consisted of a Moving-Bed Biofilm Reactor (MBBR) and chemical coagulation was investigated for textile wastewater treatment. The pilot scale MBBR system is composed of three MBBRs (anaerobic, aerobic-1 and aerobic-2 in series), each reactor was filled with 20% (v/v) of polyurethane-activated carbon (PU-AC) carrier for biological treatment followed by chemical coagulation with FeCl2. ln the MBBR process, 85% of COD and 70% of color (influent COD = 807.5 mg/L and color = 3,400 PtCo unit) were removed using relatively low MLSS concentration and short hydraulic retention time (HRT = 44 hr). The biologically treated dyeing wastewater was subjected to chemical coagulation. After coagulation with FeCl2, 95% of COD and 97% of color were removed overall. The combined process of MBBR and chemical coagulation has promising potential for dyeing wastewater treatment.

Nitrogen removal in moving bed sequencing batch reactor using polyurethane foam cubes of various sizes as carrier materials.

PubMed

Lim, Jun-Wei; Seng, Chye-Eng; Lim, Poh-Eng; Ng, Si-Ling; Sujari, Amat-Ngilmi Ahmad

2011-11-01

The performance of moving bed sequencing batch reactors (MBSBRs) added with 8 % (v/v) of polyurethane (PU) foam cubes as carrier media in nitrogen removal was investigated in treating low COD/N wastewater. The results indicate that MBSBR with 8-mL cubes achieved the highest total nitrogen (TN) removal efficiency of 37% during the aeration period, followed by 31%, 24% and 19 % for MBSBRs with 27-, 64- and 125-mL cubes, respectively. The increased TN removal in MBSBRs was mainly due to simultaneous nitrification and denitrification (SND) process which was verified by batch studies. The relatively lower TN removal in MBSBR with larger PU foam cubes was attributed to the observation that larger PU foam cubes were not fully attached by biomass. Higher concentrations of 8-mL PU foam cubes in batch reactors yielded higher TN removal. Copyright © 2011 Elsevier Ltd. All rights reserved.

Anaerobic biodegradation of diesel fuel-contaminated wastewater in a fluidized bed reactor.

PubMed

Cuenca, M Alvarez; Vezuli, J; Lohi, A; Upreti, S R

2006-06-01

Diesel fuel spills have a major impact on the quality of groundwater. In this work, the performance of an Anaerobic Fluidized Bed Reactor (AFBR) treating synthetic wastewater is experimentally evaluated. The wastewater comprises tap water containing 100, 200 and 300 mg/L of diesel fuel and nutrients. Granular, inert, activated carbon particles are employed to provide support for biomass inside the reactor where diesel fuel is the sole source of carbon for anaerobic microorganisms. For different rates of organic loading, the AFBR performance is evaluated in terms of the removal of diesel fuel as well as chemical oxygen demand (COD) from wastewater. For the aforementioned diesel fuel concentrations and a wastewater flow rate of 1,200 L/day, the COD removal ranges between 61.9 and 84.1%. The concentration of diesel fuel in the effluent is less than 50 mg/L, and meets the Level II groundwater standards of the MUST guidelines of Alberta.

Soil bed reactor work of the Environmental Research Lab. of the University of Arizona in support of the research and development of Biosphere 2

NASA Technical Reports Server (NTRS)

Frye, Robert

1990-01-01

Research at the Environmental Research Lab in support of Biosphere 2 was both basic and applied in nature. One aspect of the applied research involved the use of biological reactors for the scrubbing of trace atmospheric organic contaminants. The research involved a quantitative study of the efficiency of operation of Soil Bed Reactors (SBR) and the optimal operating conditions for contaminant removal. The basic configuration of a SBR is that air is moved through a living soil that supports a population of plants. Upon exposure to the soil, contaminants are either passively adsorbed onto the surface of soil particles, chemically transformed in the soil to usable compounds that are taken up by the plants or microbes as a metabolic energy source and converted to CO2 and water.

Thermal valorization of post-consumer film waste in a bubbling bed gasifier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martínez-Lera, S., E-mail: susanamartinezlera@gmail.com; Torrico, J.; Pallarés, J.

2013-07-15

Highlights: • Film waste from packaging is a common waste, a fraction of which is not recyclable. • Gasification can make use of the high energy value of the non-recyclable fraction. • This waste and two reference polymers were gasified in a bubbling bed reactor. • This experimental research proves technical feasibility of the process. • It also analyzes impact of composition and ER on the performance of the plant. - Abstract: The use of plastic bags and film packaging is very frequent in manifold sectors and film waste is usually present in different sources of municipal and industrial wastes.more » A significant part of it is not suitable for mechanical recycling but could be safely transformed into a valuable gas by means of thermal valorization. In this research, the gasification of film wastes has been experimentally investigated through experiments in a fluidized bed reactor of two reference polymers, polyethylene and polypropylene, and actual post-consumer film waste. After a complete experimental characterization of the three materials, several gasification experiments have been performed to analyze the influence of the fuel and of equivalence ratio on gas production and composition, on tar generation and on efficiency. The experiments prove that film waste and analogue polymer derived wastes can be successfully gasified in a fluidized bed reactor, yielding a gas with a higher heating value in a range from 3.6 to 5.6 MJ/m{sup 3} and cold gas efficiencies up to 60%.« less

Biofilm effect on flow structure over a permeable bed

NASA Astrophysics Data System (ADS)

Kazemifar, Farzan; Blois, Gianluca; Aybar, Marcelo; Perez-Calleja, Patricia; Nerenberg, Robert; Sinha, Sumit; Hardy, Richard; Best, James; Sambrook Smith, Gregory; Christensen, Kenneth

2017-11-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces in natural and industrial settings, such as water distribution systems and riverbeds among others. The permeable, heterogeneous, and deformable structure of biofilms can influence mass and momentum transport between the subsurface and freestream. However, this interaction is not fully understood, in part due to technical obstacles impeding quantitative experimental investigations. In this work, the effect of biofilm on flow structure over a permeable bed is studied. Experiments are conducted in a closed water channel equipped with an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent recirculating reactor for biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction. Funded by UK Natural Environment Research Council.

The influence of temperature on limestone sulfation and attrition under fluidized bed combustion conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montagnaro, Fabio; Salatino, Piero; Dipartimento di Ingegneria Chimica - Universita degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Napoli

2010-04-15

The influence of temperature on attrition of two limestones during desulfurization in a fluidized bed reactor was investigated. Differences in the microstructure of the two limestones were reflected by a different thickness of the sulfate shell formed upon sulfation and by a different value of the ultimate calcium conversion degree. Particle attrition and fragmentation were fairly small under moderately bubbling fluidization conditions for both limestones. An increase of temperature from 850 C to 900 C led to an increase of the attrition rate, most likely because of a particle weakening effect caused by a faster CO{sub 2} evolution during calcination.more » This weakening effect, however, was not sufficiently strong to enhance particle fragmentation in the bed. The progress of sulfation, associated to the build-up of a hard sulfate shell around the particles, led in any case to a decrease of the extent of attrition. Sulfation at 900 C was less effective than at 850 C, and this was shown to be related to the porosimetric features of the different samples. (author)« less

Apparatus for controlling molten core debris

DOEpatents

Golden, Martin P. [Trafford, PA; Tilbrook, Roger W. [Monroeville, PA; Heylmun, Neal F. [Pittsburgh, PA

1977-07-19

Apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed.

Multi-Megawatt Space Nuclear Power Generation

DTIC Science & Technology

1993-06-28

electric generation, both for open- and closed-cycle opera- tion. These reactors use the particulate fuel of the type developed for HTGR reactors. What...commercial HTGR power reactors, the particles are held in place and directly cooled. Figure 2.7 shows the two types of fuel particles developed for...of MW(e), for pulsed energy devices. The FBR would use HTGR -type particle fuel , contained in a annular bed be- tween two porous frits. Helium would

Synthoil hydrodynamics. Combined third and fourth quarterly report, December 1, 1975--May 31, 1976

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brenner, H.; Prieve, D.C.; Fitch, B.

1977-08-01

This report deals with two-phase flow (gas and liquid) in a packed bed in the synthoil process reactor and preheater; in particular, nonuniform radial distribution of the liquid phase is studied. In addition, temperature profiles and possible instability of control due to the exothermic reactions are studied with respect to the synthoil reactor. This factor may limit the reactor diameter to about six inches. (LTN)

Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed.

PubMed

Sun, Rui; Ismail, Tamer M; Ren, Xiaohan; Abd El-Salam, M

2015-05-01

In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k-ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW. Copyright © 2015 Elsevier Ltd. All rights reserved.

Water softening by induced crystallization in fluidized bed.

PubMed

Chen, Yuefang; Fan, Rong; An, Danfeng; Cheng, Yujie; Tan, Hazel

2016-12-01

Fluidized bed and induced crystallization technology were combined to design a new type of induced crystallization fluidized bed reactor. The added particulate matter served as crystal nucleus to induce crystallization so that the insoluble material, which was in a saturated state, could precipitate on its surface. In this study, by filling the fluidized bed with quartz sand and by adjusting water pH, precipitation of calcium carbonate was induced on the surface of quartz sand, and the removal of water hardness was achieved. With a reactor influent flow of 60L/hr, a fixed-bed height of 0.5m, pH value of 9.5, quartz sand nuclear diameter of 0.2-0.4mm, and a reflux ratio of 60%, the effluent concentration of calcium hardness was reduced to 60mg/L and 86.6% removal efficiency was achieved. The resulting effluent reached the quality standard set for circulating cooling water. Majority of the material on the surface of quartz sand was calculated to be calcium carbonate based on energy spectrum analysis and moisture content was around 15.994%. With the low moisture content, dewatering treatment is no longer required and this results to cost savings on total water treatment process. Copyright © 2016. Published by Elsevier B.V.

Kinetics of thermophilic anaerobes in fixed-bed reactors.

PubMed

Perez, M; Romero, L I; Sales, D

2001-08-01

The main objective of this study is to estimate growth kinetic constants and the concentration of "active" attached biomass in two anaerobic thermophilic reactors which contain different initial sizes of immobilized anaerobic mixed cultures and decompose distillery wastewater. This paper studies the substrate decomposition in two lab-scale fixed-bed reactors operating at batch conditions with corrugated tubes as support media. It can be demonstrated that high micro-organisms-substrate ratios favor the degradation activity of the different anaerobic cultures, allowing the stable operation without lag-phases and giving better quality in effluent. The kinetic parameters obtained--maximum specific growth rates (mu(max)), non-biodegradable substrate (S(NB)) and "active or viable biomass" concentrations (X(V0))--were obtained by applying the Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz], with COD as substrate and methane (CH4) as the main product of the anaerobic process. This method is suitable to calculate and to differentiate the main kinetic parameters of both the total anaerobic mixed culture and the methanogenic population. Comparison of experimental measured concentration of volatile attached solids (VS(att)) in both reactors with the estimated "active" biomass concentrations obtained by applying Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz] shows that a large amount of inert matter is present in the fixed-bed reactor.

In Situ and ex Situ Catalytic Pyrolysis of Pine in a Bench-Scale Fluidized Bed Reactor System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iisa, Kristiina; French, Richard J.; Orton, Kellene A.

In situ and ex situ catalytic pyrolysis were compared in a system with two 2-in. bubbling fluidized bed reactors. Pine was pyrolyzed in the system with a catalyst, HZSM-5 with a silica-to-alumina ratio of 30, placed either in the first (pyrolysis) reactor or the second (upgrading) reactor. Both the pyrolysis and upgrading temperatures were 500 degrees C, and the weight hourly space velocity was 1.1 h -1. Five catalytic cycles were completed in each experiment. The catalytic cycles were continued until oxygenates in the vapors became dominant. The catalyst was then oxidized, after which a new catalytic cycle was begun.more » The in situ configuration gave slightly higher oil yield but also higher oxygen content than the ex situ configuration, which indicates that the catalyst deactivated faster in the in situ configuration than the ex situ configuration. Analysis of the spent catalysts confirmed higher accumulation of metals in the in situ experiment. In all experiments, the organic oil mass yields varied between 14 and 17% and the carbon efficiencies between 20 and 25%. The organic oxygen concentrations in the oils were 16-18%, which represented a 45% reduction compared to corresponding noncatalytic pyrolysis oils prepared in the same fluidized bed reactor system. GC/MS analysis showed the oils to contain one- to four-ring aromatic hydrocarbons and a variety of oxygenates (phenols, furans, benzofurans, methoxyphenols, naphthalenols, indenols). Lastly, high fractions of oxygen were rejected as water, CO, and CO 2, which indicates the importance of dehydration, decarbonylation, and decarboxylation reactions. Light gases were the major sources of carbon losses, followed by char and coke.« less

In Situ and ex Situ Catalytic Pyrolysis of Pine in a Bench-Scale Fluidized Bed Reactor System

DOE PAGES

Iisa, Kristiina; French, Richard J.; Orton, Kellene A.; ...

2016-02-03

In situ and ex situ catalytic pyrolysis were compared in a system with two 2-in. bubbling fluidized bed reactors. Pine was pyrolyzed in the system with a catalyst, HZSM-5 with a silica-to-alumina ratio of 30, placed either in the first (pyrolysis) reactor or the second (upgrading) reactor. Both the pyrolysis and upgrading temperatures were 500 degrees C, and the weight hourly space velocity was 1.1 h -1. Five catalytic cycles were completed in each experiment. The catalytic cycles were continued until oxygenates in the vapors became dominant. The catalyst was then oxidized, after which a new catalytic cycle was begun.more » The in situ configuration gave slightly higher oil yield but also higher oxygen content than the ex situ configuration, which indicates that the catalyst deactivated faster in the in situ configuration than the ex situ configuration. Analysis of the spent catalysts confirmed higher accumulation of metals in the in situ experiment. In all experiments, the organic oil mass yields varied between 14 and 17% and the carbon efficiencies between 20 and 25%. The organic oxygen concentrations in the oils were 16-18%, which represented a 45% reduction compared to corresponding noncatalytic pyrolysis oils prepared in the same fluidized bed reactor system. GC/MS analysis showed the oils to contain one- to four-ring aromatic hydrocarbons and a variety of oxygenates (phenols, furans, benzofurans, methoxyphenols, naphthalenols, indenols). Lastly, high fractions of oxygen were rejected as water, CO, and CO 2, which indicates the importance of dehydration, decarbonylation, and decarboxylation reactions. Light gases were the major sources of carbon losses, followed by char and coke.« less

Enzymatic conversion of sunflower oil to biodiesel in a solvent-free system: process optimization and the immobilized system stability.

PubMed

Ognjanovic, Nevena; Bezbradica, Dejan; Knezevic-Jugovic, Zorica

2009-11-01

The feasibility of using the commercial immobilized lipase from Candida antarctica (Novozyme 435) to synthesize biodiesel from sunflower oil in a solvent-free system has been proved. Using methanol as an acyl acceptor and the response surface methodology as an optimization technique, the optimal conditions for the transesterification has been found to be: 45 degrees C, 3% of enzyme based on oil weight, 3:1 methanol to oil molar ratio and with no added water in the system. Under these conditions, >99% of oil conversion to fatty acid methyl ester (FAME) has been achieved after 50 h of reaction, but the activity of the immobilized lipase decreased markedly over the course of repeated runs. In order to improve the enzyme stability, several alternative acyl acceptors have been tested for biodiesel production under solvent-free conditions. The use of methyl acetate seems to be of great interest, resulting in high FAME yield (95.65%) and increasing the half-life of the immobilized lipase by about 20.1 times as compared to methanol. The reaction has also been verified in the industrially feasible reaction system including both a batch stirred tank reactor and a packed bed reactor. Although satisfactory performance in the batch stirred tank reactor has been achieved, the kinetics in a packed bed reactor system seems to have a slightly better profile (93.6+/-3.75% FAME yield after 8-10 h), corresponding to the volumetric productivity of 48.5 g/(dm(3) h). The packed bed reactor has operated for up to 72 h with almost no loss in productivity, implying that the proposed process and the immobilized system could provide a promising solution for the biodiesel synthesis at the industrial scale.

Application and Discussion of Dual Fluidized Bed Reactor in Biomass Energy Utilization

NASA Astrophysics Data System (ADS)

Guan, Haibin; Fan, Xiaoxu; Zhao, Baofeng; Yang, Liguo; Sun, Rongfeng

2018-01-01

As an important clean and renewable energy, biomass has a broad market prospect. The dual fluidized bed is widely used in biomass gasification technology, and has become an important way of biomass high-value utilization. This paper describes the basic principle of dual fluidized bed gasification, from the gas composition, tar content and thermal efficiency of the system point of view, analyzes and summarizes several typical dual fluidized bed biomass gasification technologies, points out the existence of gas mixing, the external heat source, catalyst development problems on gas. Finally, it is clear that the gasification of biomass in dual fluidized bed is of great industrial application and development prospect.

Apparatus and method for determining solids circulation rate

DOEpatents

Ludlow, J Christopher [Morgantown, WV; Spenik, James L [Morgantown, WV

2012-02-14

The invention relates to a method of determining bed velocity and solids circulation rate in a standpipe experiencing a moving packed bed flow, such as the in the standpipe section of a circulating bed fluidized reactor The method utilizes in-situ measurement of differential pressure over known axial lengths of the standpipe in conjunction with in-situ gas velocity measurement for a novel application of Ergun equations allowing determination of standpipe void fraction and moving packed bed velocity. The method takes advantage of the moving packed bed property of constant void fraction in order to integrate measured parameters into simultaneous solution of Ergun-based equations and conservation of mass equations across multiple sections of the standpipe.

Dynamic Modeling and Control Studies of a Two-Stage Bubbling Fluidized Bed Adsorber-Reactor for Solid-Sorbent CO{sub 2} Capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Modekurti, Srinivasarao; Bhattacharyya, Debangsu; Zitney, Stephen E.

2013-07-31

A one-dimensional, non-isothermal, pressure-driven dynamic model has been developed for a two-stage bubbling fluidized bed (BFB) adsorber-reactor for solid-sorbent carbon dioxide (CO{sub 2}) capture using Aspen Custom Modeler® (ACM). The BFB model for the flow of gas through a continuous phase of downward moving solids considers three regions: emulsion, bubble, and cloud-wake. Both the upper and lower reactor stages are of overflow-type configuration, i.e., the solids leave from the top of each stage. In addition, dynamic models have been developed for the downcomer that transfers solids between the stages and the exit hopper that removes solids from the bottom ofmore » the bed. The models of all auxiliary equipment such as valves and gas distributor have been integrated with the main model of the two-stage adsorber reactor. Using the developed dynamic model, the transient responses of various process variables such as CO{sub 2} capture rate and flue gas outlet temperatures have been studied by simulating typical disturbances such as change in the temperature, flowrate, and composition of the incoming flue gas from pulverized coal-fired power plants. In control studies, the performance of a proportional-integral-derivative (PID) controller, feedback-augmented feedforward controller, and linear model predictive controller (LMPC) are evaluated for maintaining the overall CO{sub 2} capture rate at a desired level in the face of typical disturbances.« less

A study on the use of the BioBall® as a biofilm carrier in a sequencing batch reactor.

PubMed

Masłoń, Adam; Tomaszek, Janusz A

2015-11-01

Described in this study are experiments conducted to evaluate the removal of organics and nutrients from synthetic wastewater by a moving bed sequencing batch biofilm reactor using BioBall® carriers as biofilm media. The work involving a 15L-laboratory scale MBSBBR (moving bed sequencing batch biofilm reactor) model showed that the wastewater treatment system was based on biochemical processes taking place with activated sludge and biofilm microorganisms developing on the surface of the BioBall® carriers. Classical nitrification and denitrification and the typical enhanced biological phosphorus removal process were achieved in the reactor analyzed, which operated with a volumetric organic loading of 0.84-0.978gCODL(-1)d(-1). The average removal efficiencies for COD, total nitrogen and total phosphorus were found to be 97.7±0.5%, 87.8±2.6% and 94.3±1.3%, respectively. Nitrification efficiency reached levels in the range 96.5-99.7%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optimization of the moving-bed biofilm sequencing batch reactor (MBSBR) to control aeration time by kinetic computational modeling: Simulated sugar-industry wastewater treatment.

PubMed

Faridnasr, Maryam; Ghanbari, Bastam; Sassani, Ardavan

2016-05-01

A novel approach was applied for optimization of a moving-bed biofilm sequencing batch reactor (MBSBR) to treat sugar-industry wastewater (BOD5=500-2500 and COD=750-3750 mg/L) at 2-4 h of cycle time (CT). Although the experimental data showed that MBSBR reached high BOD5 and COD removal performances, it failed to achieve the standard limits at the mentioned CTs. Thus, optimization of the reactor was rendered by kinetic computational modeling and using statistical error indicator normalized root mean square error (NRMSE). The results of NRMSE revealed that Stover-Kincannon (error=6.40%) and Grau (error=6.15%) models provide better fits to the experimental data and may be used for CT optimization in the reactor. The models predicted required CTs of 4.5, 6.5, 7 and 7.5 h for effluent standardization of 500, 1000, 1500 and 2500 mg/L influent BOD5 concentrations, respectively. Similar pattern of the experimental data also confirmed these findings. Copyright © 2016 Elsevier Ltd. All rights reserved.

Demand-driven biogas production from sugar beet silage in a novel fixed bed disc reactor under mesophilic and thermophilic conditions.

PubMed

Terboven, Christiane; Ramm, Patrice; Herrmann, Christiane

2017-10-01

A newly developed fixed bed disc reactor (FBDR) which combines biofilm formation on biofilm carriers and reactor agitation in one single system was assessed for its applicability to demand-driven biogas production by variable feeding of sugar beet silage. Five different feeding patterns were studied at an organic loading of 4g VS L -1 d -1 under mesophilic and thermophilic conditions. High methane yields of 449-462L N kg VS were reached. Feeding variable punctual loadings caused immediate response with 1.2- to 3.5-fold increase in biogas production rates within 15min. Although variable feeding did not induce process instability, a temporary decrease in pH-value and methane concentration below 40% occurred. Thermophilic temperature was advantageous as it resulted in a more rapid, higher methane production and less pronounced decrease in methane content after feeding. The FBDR was demonstrated to be well-suited for flexible biogas production, but further research and comparison with traditional reactor systems are required. Copyright © 2017 Elsevier Ltd. All rights reserved.

Continuous production of pectinase by immobilized yeast cells on spent grains.

PubMed

Almeida, Catarina; Brányik, Tomás; Moradas-Ferreira, Pedro; Teixeira, José

2003-01-01

A yeast strain secreting endopolygalacturonase was used in this work to study the possibility of continuous production of this enzyme. It is a feasible and interesting alternative to fungal batch production essentially due to the specificity of the type of pectinase excreted by Kluyveromyces marxianus CCT 3172, to the lower broth viscosity and to the easier downstream operations. In order to increase the reactors' productivity, a cellulosic carrier obtained from barley spent grains was tested as an immobilization support. Two types of reactors were studied for pectinase production using glucose as a carbon and energy source--a continuous stirred tank reactor (CSTR) and a packed bed reactor (PBR) with recycled flow. The highest value for pectinase volumetric productivity (P(V)=0.98 U ml(-1) h(-1)) was achieved in the PBR for D=0.40 h(-1), a glucose concentration on the inlet of S(in)=20 g l(-1), and a biomass load in the support of X(i)=0.225 g g(-1). The results demonstrate the attractiveness of the packed bed system for pectinase production.

Testing of an advanced thermochemical conversion reactor system

NASA Astrophysics Data System (ADS)

1990-01-01

This report presents the results of work conducted by MTCI to verify and confirm experimentally the ability of the MTCI gasification process to effectively generate a high-quality, medium-Btu gas from a wider variety of feedstock and waste than that attainable in air-blown, direct gasification systems. The system's overall simplicity, due to the compact nature of the pulse combustor, and the high heat transfer rates attainable within the pulsating flow resonance tubes, provide a decided and near-term potential economic advantage for the MTCI indirect gasification system. The primary objective was the design, construction, and testing of a Process Design Verification System for an indirectly heated, thermochemical fluid-bed reactor and a pulse combustor an an integrated system that can process alternative renewable sources of energy such as biomass, black liquor, municipal solid waste and waste hydrocarbons, including heavy oils into a useful product gas. The test objectives for the biomass portion of this program were to establish definitive performance data on biomass feedstocks covering a wide range of feedstock qualities and characteristics. The test objectives for the black liquor portion of this program were to verify the operation of the indirect gasifier on commercial black liquor containing 65 percent solids at several temperature levels and to characterize the bed carbon content, bed solids particle size and sulfur distribution as a function of gasification conditions.

Investigations on humic acid removal from water using surfactant-modified zeolite as adsorbent in a fixed-bed reactor

NASA Astrophysics Data System (ADS)

Elsheikh, Awad F.; Ahmad, Umi Kalthom; Ramli, Zainab

2017-10-01

Natural organic matter (NOM) is ubiquitous in aquatic environments and has recently become an issue of worldwide concern in drinking water treatment. The major component of NOM is humic acids (HA). In this study, a natural zeolite (mordenite) was modified employing hexadecyltrimethylammonium bromide (HDTMA) to enhance greater efficient sites for sorption of HA. The natural zeolite and surfactant-modified zeolite (SMZ) were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectrometer (FT-IR), N2 Adsorption-desorption isotherms and BET-specific surface area, thermographic analysis, derivative thermographic analysis (TGA-DTA) and Field emission scanning electron microscopy (FESEM). A fixed-bed reactor was used for the removal of HA and the effects of different experimental parameters such as HDTMA loading levels, HA solution flow rate, solution pH and eluent concentration were investigated. The results indicated that the SMZ bed with HDTMA loading of 75% of external cation exchange capacity (ECEC) at a flow rate of 2 BV/h and pH of 10 showed the greatest enhanced removal efficiency of HA while ethanol solutions (25%v/v) with feed flow rate of 2 BV/h were sufficient for complete regeneration of SMZ and desorption of HA. Measurements of surface area of SMZ indicated that a monolayer formation of the surfactant at those conditions allowed the optimum removal of HA.

Phenol removal performance and microbial community shift during pH shock in a moving bed biofilm reactor (MBBR).

PubMed

Zhou, Hao; Wang, Guochen; Wu, Minghuo; Xu, Weiping; Zhang, Xuwang; Liu, Lifen

2018-06-05

A moving bed biofilm reactor (MBBR) effectively removes pollutants and even runs under extreme conditions. However, the pH shock resistance of a biofilm in MBBRs has been rarely reported. In this study, simulated phenol wastewater with acidic shock (pH 7.5-3.0) was used. In the pH shock phase, the phenol and COD removal efficiencies initially decreased and gradually increased to more than 90%. Microscopic studies showed that the superficial biofilm was mainly composed of fungi (yeasts) in the acidic pH shock phase. The microbial community composition in the acidic pH shock phase was significantly different from those in other phases. Firmicutes and Ascomycota were the dominant bacterial and fungal phyla in this stage, respectively. 16S rRNA gene-based functional annotation indicated that functional profiles related to aromatic compound degradation existed in all of the stages. Therefore, MBBRs show potential for the treatment of phenolic wastewater exposed to pH shock. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of micropollutant removal and fouling reduction in a hybrid moving bed biofilm reactor-membrane bioreactor system.

PubMed

Luo, Yunlong; Jiang, Qi; Ngo, Huu H; Nghiem, Long D; Hai, Faisal I; Price, William E; Wang, Jie; Guo, Wenshan

2015-09-01

A hybrid moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) system and a conventional membrane bioreactor (CMBR) were compared in terms of micropollutant removal efficiency and membrane fouling propensity. The results show that the hybrid MBBR-MBR system could effectively remove most of the selected micropollutants. By contrast, the CMBR system showed lower removals of ketoprofen, carbamazepine, primidone, bisphenol A and estriol by 16.2%, 30.1%, 31.9%, 34.5%, and 39.9%, respectively. Mass balance calculations suggest that biological degradation was the primary removal mechanism in the MBBR-MBR system. During operation, the MBBR-MBR system exhibited significantly slower fouling development as compared to the CMBR system, which could be ascribed to the wide disparity in the soluble microbial products (SMP) levels between MBBR-MBR (4.02-6.32 mg/L) and CMBR (21.78 and 33.04 mg/L). It is evident that adding an MBBR process prior to MBR treatment can not only enhance micropollutant elimination but also mitigate membrane fouling. Copyright © 2015 Elsevier Ltd. All rights reserved.

Production of bio-oil rich in acetic acid and phenol from fast pyrolysis of palm residues using a fluidized bed reactor: Influence of activated carbons.

PubMed

Jeong, Jae-Yong; Lee, Uen-Do; Chang, Won-Seok; Jeong, Soo-Hwa

2016-11-01

In this study, palm residues were pyrolyzed in a bench-scale (3kg/h) fast pyrolysis plant equipped with a fluidized bed reactor and bio-oil separation system for the production of bio-oil rich in acetic acid and phenol. Pyrolysis experiments were performed to investigate the effects of reaction temperature and the types and amounts of activated carbon on the bio-oil composition. The maximum bio-oil yield obtained was approximately 47wt% at a reaction temperature of 515°C. The main compounds produced from the bio-oils were acetic acid, hydroxyacetone, phenol, and phenolic compounds such as cresol, xylenol, and pyrocatechol. When coal-derived activated carbon was applied, the acetic acid and phenol yields in the bio-oils reached 21 and 19wt%, respectively. Finally, bio-oils rich in acetic acid and phenol could be produced separately by using an in situ bio-oil separation system and activated carbon as an additive. Copyright © 2016 Elsevier Ltd. All rights reserved.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater

NASA Astrophysics Data System (ADS)

Ahmadi, Ehsan; Yousefzadeh, Samira; Ansari, Mohsen; Ghaffari, Hamid Reza; Azari, Ali; Miri, Mohammad; Mesdaghinia, Alireza; Nabizadeh, Ramin; Kakavandi, Babak; Ahmadi, Peyman; Badi, Mojtaba Yegane; Gholami, Mitra; Sharafi, Kiomars; Karimaei, Mostafa; Ghoochani, Mahboobeh; Brahmand, Masoud Binesh; Mohseni, Seyed Mohsen; Sarkhosh, Maryam; Rezaei, Soheila; Asgharnia, Hosseinali; Dehghanifard, Emad; Jafari, Behdad; Mortezapour, Alireza; Moghaddam, Vahid Kazemi; Mahmoudi, Mohammad Molla; Taghipour, Nader

2017-02-01

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater.

PubMed

Ahmadi, Ehsan; Yousefzadeh, Samira; Ansari, Mohsen; Ghaffari, Hamid Reza; Azari, Ali; Miri, Mohammad; Mesdaghinia, Alireza; Nabizadeh, Ramin; Kakavandi, Babak; Ahmadi, Peyman; Badi, Mojtaba Yegane; Gholami, Mitra; Sharafi, Kiomars; Karimaei, Mostafa; Ghoochani, Mahboobeh; Brahmand, Masoud Binesh; Mohseni, Seyed Mohsen; Sarkhosh, Maryam; Rezaei, Soheila; Asgharnia, Hosseinali; Dehghanifard, Emad; Jafari, Behdad; Mortezapour, Alireza; Moghaddam, Vahid Kazemi; Mahmoudi, Mohammad Molla; Taghipour, Nader

2017-02-20

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal.

Pyrolysis of oil palm mesocarp fiber and palm frond in a slow-heating fixed-bed reactor: A comparative study.

PubMed

Kabir, G; Mohd Din, A T; Hameed, B H

2017-10-01

Oil palm mesocarp fiber (OPMF) and palm frond (PF) were respectively devolatilized by pyrolysis to OPMF-oil and PF-oil bio-oils and biochars, OPMF-char and PF-char in a slow-heating fixed-bed reactor. In particular, the OPMF-oil and PF-oil were produced to a maximum yield of 48wt% and 47wt% bio-oils at 550°C and 600°C, respectively. The high heating values (HHVs) of OPMF-oil and PF-oil were respectively found to be 23MJ/kg and 21MJ/kg, whereas 24.84MJ/kg and 24.15MJ/kg were for the corresponding biochar. The HHVs of the bio-oils and biochars are associated with low O/C ratios to be higher than those of the corresponding biomass. The Fourier transform infrared spectra and peak area ratios highlighted the effect of pyrolysis temperatures on the bio-oil compositions. The bio-oils are pervaded with numerous oxygenated carbonyl and aromatic compounds as suitable feedstocks for renewable fuels and chemicals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Application of rumen microbes to enhance food waste hydrolysis in acidogenic leach-bed reactors.

PubMed

Yan, Bing Hua; Selvam, Ammaiyappan; Wong, Jonathan W C

2014-09-01

Effect of rumen microorganisms on hydrolysis of food waste in leach bed reactor (LBR) was investigated. LBRs were inoculated (20%, w/w) with cow manure and anaerobically digested sludge at different ratios, 0:1 (LBR-A), 1:3 (LBR-B), 1:1 (LBR-C), 3:1 (LBR-D) and 1:0 (LBR-E). High volatile solids (VS) conversion efficiency of 68% was achieved in LBR-E. Compared with LBR-A, chemical oxygen demand, total soluble products and total Kjeldahl nitrogen leaching of LBR-E were increased by 16%, 14.3% and 27%, respectively. Recovery of the highest amounts of ethanol and butyrate in LBR-E indicated that the metabolic pathway mediated by rumen microorganisms was favorable for subsequent methanogenesis. Phylogenetic analysis confirmed that the enhanced hydrolysis in LBR-E was mainly due to strong degraders, e.g. Enterobacter, Bifidobacterium thermacidophilum and Caloramator sourced from cow manure. Results demonstrate that rumen microorganisms rapidly degrade the VS and produce useful VFAs with high methane yields in subsequent methanogenesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Organic loading rate impact on biohydrogen production and microbial communities at anaerobic fluidized thermophilic bed reactors treating sugarcane stillage.

PubMed

Santos, Samantha Christine; Rosa, Paula Rúbia Ferreira; Sakamoto, Isabel Kimiko; Varesche, Maria Bernadete Amâncio; Silva, Edson Luiz

2014-05-01

This study aimed to evaluate the effect of high organic loading rates (OLR) (60.0-480.00 kg COD m(-3)d(-1)) on biohydrogen production at 55°C, from sugarcane stillage for 15,000 and 20,000 mg CODL(-1), in two anaerobic fluidized bed reactors (AFBR1 and AFBR2). It was obtained, for H2 yield and content, a decreasing trend by increasing the OLR. The maximum H2 yield was observed in AFBR1 (2.23 mmol g COD added(-1)). The volumetric H2 production was proportionally related to the applied hydraulic retention time (HRT) of 6, 4, 2 and 1h and verified in AFBR1 the highest value (1.49 L H2 h(-1)L(-1)). Among the organic acids obtained, there was a predominance of lactic acid (7.5-22.5%) and butyric acid (9.4-23.8%). The microbial population was set with hydrogen-producing fermenters (Megasphaera sp.) and other organisms (Lactobacillus sp.). Copyright © 2014 Elsevier Ltd. All rights reserved.

Co-production of furfural and acetic acid from corncob using ZnCl2 through fast pyrolysis in a fluidized bed reactor.

PubMed

Oh, Seung-Jin; Jung, Su-Hwa; Kim, Joo-Sik

2013-09-01

Corncob was pyrolyzed using ZnCl2 in a pyrolysis plant equipped with a fluidized bed reactor to co-produce furfural and acetic acid. The effects of reaction conditions, the ZnCl2 content and contacting method of ZnCl2 with corncob on the yields of furfural and acetic acid were investigated. The pyrolysis was performed within the temperature range between 310 and 410°C, and the bio-oil yield were 30-60 wt% of the product. The furfural yield increased up to 8.2 wt%. The acetic acid yield was maximized with a value of 13.1 wt%. A lower feed rate in the presence of ZnCl2 was advantageous for the production of acetic acid. The fast pyrolysis of a smaller corncob sample mechanically mixed with 20 wt% of ZnCl2 gave rise to a distinct increase in furfural. A high selectivity for furfural and acetic acid in bio-oil would make the pyrolysis of corncob with ZnCl2 very economically attractive. Copyright © 2013 Elsevier Ltd. All rights reserved.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater

PubMed Central

Ahmadi, Ehsan; Yousefzadeh, Samira; Ansari, Mohsen; Ghaffari, Hamid Reza; Azari, Ali; Miri, Mohammad; Mesdaghinia, Alireza; Nabizadeh, Ramin; Kakavandi, Babak; Ahmadi, Peyman; Badi, Mojtaba Yegane; Gholami, Mitra; Sharafi, Kiomars; Karimaei, Mostafa; Ghoochani, Mahboobeh; Brahmand, Masoud Binesh; Mohseni, Seyed Mohsen; Sarkhosh, Maryam; Rezaei, Soheila; Asgharnia, Hosseinali; Dehghanifard, Emad; Jafari, Behdad; Mortezapour, Alireza; Moghaddam, Vahid Kazemi; Mahmoudi, Mohammad Molla; Taghipour, Nader

2017-01-01

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal. PMID:28216654

Analysis of fixed bed data for the extraction of a rate mechanism for the reaction of hematite with methane

DOE PAGES

Breault, Ronald W.; Monazam, Esmail R.

2015-04-01

In this study, chemical looping combustion is a promising technology for the capture of CO 2 involving redox materials as oxygen carriers. The effects of reduction conditions, namely, temperature and fuel partial pressure on the conversion products are investigated. The experiments were conducted in a laboratory fixed-bed reactor that was operated cyclically with alternating reduction and oxidation periods. Reactions are assumed to occur in the shell surrounding the particle grains with diffusion of oxygen to the surface from the grain core. Activation energies for the shell and core reactions range from 9 to 209 kJ/mol depending on the reaction step.

Packed-bed catalytic cracking of oak derived pyrolytic vapors

USDA-ARS?s Scientific Manuscript database

Catalytic upgrading of pyrolysis vapors derived from oak was carried out using a fixed-bed catalytic column at 425 deg C. The vapors were drawn by splitting a fraction from the full stream of vapors produced at 500 deg C in a 5 kg/hr bench-scale fast pyrolysis reactor system downstream the cyclone s...

Process development and modeling of fluidized-bed reactor with coimmobilized biocatalyst for fuel ethanol production

NASA Astrophysics Data System (ADS)

Sun, May Yongmei

This research focuses on two steps of commercial fuel ethanol production processes: the hydrolysis starch process and the fermentation process. The goal of this research is to evaluate the performance of co-immobilized biocatalysts in a fluidized bed reactor with emphasis on economic and engineering aspects and to develop a predictive mathematical model for this system. The productivity of an FBR is higher than productivity of a traditional batch reactor or CSTR. Fluidized beds offer great advantages over packed beds for immobilized cells when small particles are used or when the reactant feed contains suspended solids. Plugging problems, excessive pressure drops (and thus attrition), or crushing risks may be avoided. No mechanical stirring is required as mixing occurs due to the natural turbulence in the fluidized process. Both enzyme and microorganism are immobilized in one catalyst bead which is called co-immobilization. Inside this biocatalyst matrix, starch is hydrolyzed by the enzyme glucoamylase to form glucose and then converted to ethanol and carbon dioxide by microorganisms. Two biocatalysts were evaluated: (1) co-immobilized yeast strain Saccharomyces cerevisiae and glucoamylase. (2) co-immobilized Zymomonas mobilis and glucoamylase. A co-immobilized biocatalyst accomplishes the simultaneous saccharification and fermentation (SSF process). When compared to a two-step process involving separate saccharification and fermentation stages, the SSF process has productivity values twice that given by the pre-saccharified process when the time required for pre-saccharification (15--25 h) was taken into account. The SSF process should also save capital cost. The information about productivity, fermentation yield, concentration profiles along the bed, ethanol inhibition, et al., was obtained from the experimental data. For the yeast system, experimental results showed that: no apparent decrease of productivity occurred after two and half months, the productivity was 25--44g/L-hr (based on reactor volume), the average yield was 0.45 g ethanol/g starch, the biocatalyst retained physical integrity and contamination did not affect fermentation. For the Z. mobilis system the maximum volumetric productivity was 38 g ethanol/L-h, the average yield was 0.51 g ethanol/g starch and the FBR was successfully operated for almost one month. In order to develop, scale-up and economically evaluate this system more efficiently, a predictive mathematical model that is based on fundamental principles was developed and verified. This model includes kinetics of reactions, transport phenomena of the reactant and product by diffusion within the biocatalyst bead, and the hydrodynamics of the three phase fluidized bed. The co-immobilized biocatalyst involves a consecutive reaction mechanism The mathematical descriptions of the effectiveness factors of reactant and the intermediate product were developed. Hydrodynamic literature correlations were used to develop the dispersion coefficient and gas, liquid, and solid holdup. The solutions of coupled non-linear second order equations for biocatalyst bead and reactor together with the boundary conditions were solved numerically. This model gives considerable information about the system, such as concentration profiles inside both the beads and column, flow rate and feed concentration influences on productivity and phase hold up, and the influence of enzyme and cell mass loading in the catalyst. This model is generic in nature such that it can be easily applied to a diverse set of applications and operating conditions.

An Air-Stripping Packed Bed Combined with a Biofilm-Type Biological Process for Treating BTEX and Total Petroleum Hydrocarbon Contaminated Groudwater

NASA Astrophysics Data System (ADS)

Hong, U.; Park, S.; Lim, J.; Lee, W.; Kwon, S.; Kim, Y.

2009-12-01

In this study, we examined the removal efficiency of a volatile compound (e.g. toluene) and a less volatile compound [e.g. total petroleum hydrocarbon (TPH)] using an air stripping packed bed combined with a biofilm-type biological process. We hypothesized that this system might be effective and economical to simultaneously remove both volatile and less volatile compounds. The gas-tight reactor has 5.9-inch-diameter and 48.8-inch-height. A spray nozzle was installed at the top cover to distribute the liquid evenly through reactor. The reactor was filled with polypropylene packing media for the increase of volatilization surface area and the growth of TPH degrading facultative aerobic bacteria on the surface of the packing media. In air stripping experiments, 45.6%, 71.7%, 72.0%, and 75.4% of toluene was removed at air injection rates of 0 L/min, 2.5 L/min, 4 L/min, and 6 L/min, respectively. Through the result, we confirmed that toluene removal efficiency increased by injecting higher amounts of air. TPH removal by stripping was minimal. To remove a less volatile TPH by commercial TPH degrading culture (BIO-ZYME B-52), 15-times diluted culture was circulated through the reactor for 2-3 days to build up a biofilm on the surface of packing media with 1 mg-soluble nitrogen source /L-water per 1 ppm of TPH. Experiments evaluating the degree of TPH biodegradation in this system are carrying out.

Bisphenol A removal by a Pseudomonas aeruginosa immobilized on granular activated carbon and operating in a fluidized bed reactor.

PubMed

Mita, Luigi; Grumiro, Laura; Rossi, Sergio; Bianco, Carmen; Defez, Roberto; Gallo, Pasquale; Mita, Damiano Gustavo; Diano, Nadia

2015-06-30

Serratia rubidiae, Pseudomonas aeruginosa and Escherichia coli K12 have been studied for their ability of Bisphenol A removal from aqueous systems and biofilm formation on activated granule carbon. Mathematical equations for biodegradation process have been elaborated and discussed. P. aeruginosa was found the best strain to be employed in the process of Bisphenol A removal. The yield in BPA removal of a P. aeruginosa biofilm grown on GAC and operating in a fluidized bed reactor has been evaluated. The results confirm the usefulness in using biological activated carbon (BAC process) to remove phenol compounds from aqueous systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Pyrolysis of waste tyres: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Paul T., E-mail: p.t.williams@leeds.ac.uk

2013-08-15

Graphical abstract: - Highlights: • Pyrolysis of waste tyres produces oil, gas and char, and recovered steel. • Batch, screw kiln, rotary kiln, vacuum and fluidised-bed are main reactor types. • Product yields are influenced by reactor type, temperature and heating rate. • Pyrolysis oils are complex and can be used as chemical feedstock or fuel. • Research into higher value products from the tyre pyrolysis process is reviewed. - Abstract: Approximately 1.5 billion tyres are produced each year which will eventually enter the waste stream representing a major potential waste and environmental problem. However, there is growing interest inmore » pyrolysis as a technology to treat tyres to produce valuable oil, char and gas products. The most common reactors used are fixed-bed (batch), screw kiln, rotary kiln, vacuum and fluidised-bed. The key influence on the product yield, and gas and oil composition, is the type of reactor used which in turn determines the temperature and heating rate. Tyre pyrolysis oil is chemically very complex containing aliphatic, aromatic, hetero-atom and polar fractions. The fuel characteristics of the tyre oil shows that it is similar to a gas oil or light fuel oil and has been successfully combusted in test furnaces and engines. The main gases produced from the pyrolysis of waste tyres are H{sub 2}, C{sub 1}–C{sub 4} hydrocarbons, CO{sub 2}, CO and H{sub 2}S. Upgrading tyre pyrolysis products to high value products has concentrated on char upgrading to higher quality carbon black and to activated carbon. The use of catalysts to upgrade the oil to a aromatic-rich chemical feedstock or the production of hydrogen from waste tyres has also been reported. Examples of commercial and semi-commercial scale tyre pyrolysis systems show that small scale batch reactors and continuous rotary kiln reactors have been developed to commercial scale.« less

Biodegradation of 2,4,6-trichlorophenol in a packed-bed biofilm reactor equipped with an internal net draft tube riser for aeration and liquid circulation.

PubMed

Jesús, A Gómez-De; Romano-Baez, F J; Leyva-Amezcua, L; Juárez-Ramírez, C; Ruiz-Ordaz, N; Galíndez-Mayer, J

2009-01-30

For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for liquid circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high A(D)/A(R) ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values epsilon(G), and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies ( approximately 95%), and by the stoichiometric release of chloride ions from the halogenated compound ( approximately 80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions).

Reduction of the hydraulic retention time at constant high organic loading rate to reach the microbial limits of anaerobic digestion in various reactor systems.

PubMed

Ziganshin, Ayrat M; Schmidt, Thomas; Lv, Zuopeng; Liebetrau, Jan; Richnow, Hans Hermann; Kleinsteuber, Sabine; Nikolausz, Marcell

2016-10-01

The effects of hydraulic retention time (HRT) reduction at constant high organic loading rate on the activity of hydrogen-producing bacteria and methanogens were investigated in reactors digesting thin stillage. Stable isotope fingerprinting was additionally applied to assess methanogenic pathways. Based on hydA gene transcripts, Clostridiales was the most active hydrogen-producing order in continuous stirred tank reactor (CSTR), fixed-bed reactor (FBR) and anaerobic sequencing batch reactor (ASBR), but shorter HRT stimulated the activity of Spirochaetales. Further decreasing HRT diminished Spirochaetales activity in systems with biomass retention. Based on mcrA gene transcripts, Methanoculleus and Methanosarcina were the predominantly active in CSTR and ASBR, whereas Methanosaeta and Methanospirillum activity was more significant in stably performing FBR. Isotope values indicated the predominance of aceticlastic pathway in FBR. Interestingly, an increased activity of Methanosaeta was observed during shortening HRT in CSTR and ASBR despite high organic acids concentrations, what was supported by stable isotope data. Copyright © 2016 Elsevier Ltd. All rights reserved.

Flash Pyrolysis and Fractional Pyrolysis of Oleaginous Biomass in a Fluidized-bed Reactor

NASA Astrophysics Data System (ADS)

Urban, Brook

Thermochemical conversion methods such as pyrolysis have the potential for converting diverse biomass feedstocks into liquid fuels. In particular, bio-oil yields can be maximized by implementing flash pyrolysis to facilitate rapid heat transfer to the solids along with short vapor residence times to minimize secondary degradation of bio-oils. This study first focused on the design and construction of a fluidized-bed flash pyrolysis reactor with a high-efficiency bio-oil recovery unit. Subsequently, the reactor was used to perform flash pyrolysis of soybean pellets to assess the thermochemical conversion of oleaginous biomass feedstocks. The fluidized bed reactor design included a novel feed input mechanism through suction created by flow of carrier gas through a venturi which prevented plugging problems that occur with a more conventional screw feeders. In addition, the uniquely designed batch pyrolysis unit comprised of two tubes of dissimilar diameters. The bottom section consisted of a 1" tube and was connected to a larger 3" tube placed vertically above. At the carrier gas flow rates used in these studies, the feed particles remained fluidized in the smaller diameter tube, but a reduction in carrier gas velocity in the larger diameter "disengagement chamber" prevented the escape of particles into the condensers. The outlet of the reactor was connected to two Allihn condensers followed by an innovative packed-bed dry ice condenser. Due to the high carrier gas flow rates in fluidized bed reactors, bio-oil vapors form dilute aerosols upon cooling which that are difficult to coalesce and recover by traditional heat exchange condensers. The dry ice condenser provided high surface area for inertial impaction of these aerosols and also allowed easy recovery of bio-oils after natural evaporation of the dry ice at the end of the experiments. Single step pyrolysis was performed between 250-610°C with a vapor residence time between 0.3-0.6s. At 550°C or higher, 70% of the initial feed mass was recovered as bio-oil. However, the mass of high calorific lipid-derived components in the collected bio-oils remained nearly constant at reaction temperatures above 415°C; between 80-90% of the feedstock lipids were recovered in the bio-oil fraction. In addition, multi-step fractional flash pyrolysis experiments were performed to assess the possibility of producing higher quality bio-oils since a large fraction of protein and carbohydrates degrade at lower temperatures (320-400°C). A low temperature pyrolysis step was first performed and was followed by pyrolysis of the residues at higher temperature. This fractional pyrolysis approach which produced higher quality bio-oil with low water- and nitrogen- content from the higher temperature steps.

Heat dissipating nuclear reactor with metal liner

DOEpatents

Gluekler, E.L.; Hunsbedt, A.; Lazarus, J.D.

1985-11-21

A nuclear reactor containment including a reactor vessel disposed within a cavity with capability for complete inherent decay heat removal in the earth and surrounded by a cast steel containment member which surrounds the vessel is described in this disclosure. The member has a thick basemat in contact with metal pilings. The basemat rests on a bed of porous particulate material, into which water is fed to produce steam which is vented to the atmosphere. There is a gap between the reactor vessel and the steel containment member. The containment member holds any sodium or core debris escaping from the reactor vessel if the core melts and breaches the vessel.

Heat dissipating nuclear reactor with metal liner

DOEpatents

Gluekler, Emil L.; Hunsbedt, Anstein; Lazarus, Jonathan D.

1987-01-01

Disclosed is a nuclear reactor containment including a reactor vessel disposed within a cavity with capability for complete inherent decay heat removal in the earth and surrounded by a cast steel containment member which surrounds the vessel. The member has a thick basemat in contact with metal pilings. The basemat rests on a bed of porous particulate material, into which water is fed to produce steam which is vented to the atmosphere. There is a gap between the reactor vessel and the steel containment member. The containment member holds any sodium or core debris escaping from the reactor vessel if the core melts and breaches the vessel.

Study of the efficiency of moving bed biofilm reactor (MBBR) in LAS Anionic Detergent removal from hospital wastewater: determination of removing model according to response surface methodology (RSM).

PubMed

Shokoohi, Reza; Torkshavand, Zahra; Zolghadnasab, Hassan; Alikhani, Mohammad Yousef; Hemmat, Meisam Sedighi

2017-04-01

Detergents are considered one of the important pollutants in hospital wastewater. Achieving efficient and bio-friendly methods for the removal of these pollutants is considered as a concern for environmental researchers. This study aims at studying the efficiency of a moving bed biofilm reactor (MBBR) system for removing linear alkyl benzene sulfonate (LAS) from hospital wastewater with utilization of response surface methodology (RSM). The present study was carried out on a reactor with continuous hydraulic flow using media k 1 at pilot scale to remove detergent from hospital wastewater. The effect of independent variables including contact time, percentage of media filling and mixed liquor suspended solids (MLSS) concentration of 1000-3000 mg/l on the system efficiency were assessed. Methylene blue active substances (MBAS) and chemical oxygen demand (COD) 750-850 mg/l were used by closed laboratory method in order to measure the concentration of LAS. The results revealed that the removal efficiency of LAS detergent and COD using media k 1 , retention time of 24 hours, and MLSS concentration of around 3,000 mg/l were 92.3 and 95.8%, respectively. The results showed that the MBBR system as a bio-friendly compatible method has high efficiency in removing detergents from hospital wastewater and can achieve standard output effluent in acceptable time.

Difficulties in maintaining long-term partial nitritation of ammonium-rich sludge digester liquids in a moving-bed biofilm reactor (MBBR).

PubMed

Fux, C; Huang, D; Monti, A; Siegrist, H

2004-01-01

Nitrogen can be eliminated effectively from sludge digester effluents by anaerobic ammonium oxidation (anammox), but 55-60% of the ammonium must first be oxidized to nitrite. Although a continuous flow stirred tank reactor (CSTR) with suspended biomass could be used, its hydraulic dilution rate is limited to 0.8-1 d(-1) (30 degrees C). Higher specific nitrite production rates can be achieved by sludge retention, as shown here for a moving-bed biofilm reactor (MBBR) with Kaldnes carriers on laboratory and pilot scales. The maximum nitrite production rate amounted to 2.7 gNO2-Nm(-2)d(-1) (3 gO2m(-3)d(-1), 30.5 degrees C), thus doubling the dilution rate compared to CSTR operation with suspended biomass for a supernatant with 700 gNH4-Nm(-3). Whenever the available alkalinity was fully consumed, an optimal amount of nitrite was produced. However, a significant amount of nitrate was produced after 11 months of operation, making the effluent unsuitable for anaerobic ammonium oxidation. Because the sludge retention time (SRT) is relatively long in biofilm systems, slow growth of nitrite oxidizers occurs. None of the selection criteria applied - a high ammonium loading rate, high free ammonia or low oxygen concentration - led to selective suppression of nitrite oxidation. A CSTR or SBR with suspended biomass is consequently recommended for full-scale operation.

Optimization of arsenic removal water treatment system through characterization of terminal electron accepting processes.

PubMed

Upadhyaya, Giridhar; Clancy, Tara M; Brown, Jess; Hayes, Kim F; Raskin, Lutgarde

2012-11-06

Terminal electron accepting process (TEAP) zones developed when a simulated groundwater containing dissolved oxygen (DO), nitrate, arsenate, and sulfate was treated in a fixed-bed bioreactor system consisting of two reactors (reactors A and B) in series. When the reactors were operated with an empty bed contact time (EBCT) of 20 min each, DO-, nitrate-, sulfate-, and arsenate-reducing TEAP zones were located within reactor A. As a consequence, sulfate reduction and subsequent arsenic removal through arsenic sulfide precipitation and/or arsenic adsorption on or coprecipitation with iron sulfides occurred in reactor A. This resulted in the removal of arsenic-laden solids during backwashing of reactor A. To minimize this by shifting the sulfate-reducing zone to reactor B, the EBCT of reactor A was sequentially lowered from 20 min to 15, 10, and 7 min. While 50 mg/L (0.81 mM) nitrate was completely removed at all EBCTs, more than 90% of 300 μg/L (4 μM) arsenic was removed with the total EBCT as low as 27 min. Sulfate- and arsenate-reducing bacteria were identified throughout the system through clone libraries and quantitative PCR targeting the 16S rRNA, dissimilatory (bi)sulfite reductase (dsrAB), and dissimilatory arsenate reductase (arrA) genes. Results of reverse transcriptase (RT) qPCR of partial dsrAB (i.e., dsrA) and arrA transcripts corresponded with system performance. The RT qPCR results indicated colocation of sulfate- and arsenate-reducing activities, in the presence of iron(II), suggesting their importance in arsenic removal.

Advanced treatment of swine wastewater using an agent synthesized from amorphous silica and hydrated lime.

PubMed

Tanaka, Yasuo; Hasegawa, Teruaki; Sugimoto, Kiyomi; Miura, Keiichi; Aketo, Tsuyoshi; Minowa, Nobutaka; Toda, Masaya; Kinoshita, Katsumi; Yamashita, Takahiro; Ogino, Akifumi

2014-01-01

Advanced treatment using an agent synthesized from amorphous silica and hydrated lime (M-CSH-lime) was developed and applied to swine wastewater treatment. Biologically treated wastewater and M-CSH-lime (approximately 6 w/v% slurry) were fed continuously into a column-shaped reactor from its bottom. Accumulated M-CSH-lime gradually formed a bed layer. The influent permeated this layer and contacted the M-CSH-lime, and the treatment reaction progressed. Treated liquid overflowing from the top of the reactor was neutralized with CO₂gas bubbling. The colour removal rate approximately exceeded 50% with M-CSH-lime addition rates of > 0.15 w/v%. The removal rate of PO(3⁻)(4) exceeded 80% with the addition of>0.03 w/v% of M-CSH-lime. The removal rates of coliform bacteria and Escherichia coli exceeded 99.9% with > 0.1 w/v%. Accumulated M-CSH-lime in the reactor was periodically withdrawn from the upper part of the bed layer. The content of citric-acid-soluble P₂O₅ in the recovered matter was>15% when the weight ratio of influent PO(3⁻)(4) -P to added M-CSH-lime was > 0.15. This content was comparable with commercial phosphorus fertilizer. The inhibitory effect of recovered M-CSH-lime on germination and growth of leafy vegetable komatsuna (Brassica rapa var. perviridis) was evaluated by an experiment using the Neubauer's pot. The recovered M-CSH-lime had no negative effect on germination and growth. These results suggest that advanced water treatment with M-CSH-lime was effective for simultaneous removal of colour, [Formula: see text] and coliform bacteria at an addition rate of 0.03-0.15 w/v%, and that the recovered M-CSH-lime would be suitable as phosphorus fertilizer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaron, Adam M.; Cunningham, Richard Burns; Fugate, David L.

Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, goodmore » heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels with 3 cm diameter graphite-based fuel pebbles slowly circulating up through the core. Molten salt coolant (FLiBe) at 700°C flows concurrently (at significantly higher velocity) with the pebbles and is used to remove heat generated in the reactor core (approximately 1280 W/pebble), and supply it to a power conversion system. Refueling equipment continuously sorts spent fuel pebbles and replaces spent or damaged pebbles with fresh fuel. By combining greater or fewer numbers of pebble channel assemblies, multiple reactor designs with varying power levels can be offered. The PB-AHTR design is discussed in detail in Reference [1] and is shown schematically in Fig. 1. Fig. 1. PB-AHTR concept (drawing taken from Peterson et al., Design and Development of the Modular PB-AHTR Proceedings of ICApp 08). Pebble behavior within the core is a key issue in proving the viability of this concept. This includes understanding the behavior of the pebbles thermally, hydraulically, and mechanically (quantifying pebble wear characteristics, flow channel wear, etc). The experiment being developed is an initial step in characterizing the pebble behavior under realistic PB-AHTR operating conditions. It focuses on thermal and hydraulic behavior of a static pebble bed using a convective salt loop to provide prototypic fluid conditions to the bed, and a unique inductive heating technique to provide prototypic heating in the pebbles. The facility design is sufficiently versatile to allow a variety of other experimentation to be performed in the future. The facility can accommodate testing of scaled reactor components or sub-components such as flow diodes, salt-to-salt heat exchangers, and improved pump designs as well as testing of refueling equipment, high temperature instrumentation, and other reactor core designs.« less

Surface passivation of Fe{sub 3}O{sub 4} nanoparticles with Al{sub 2}O{sub 3} via atomic layer deposition in a rotating fluidized bed reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Chen-Long; Deng, Zhang; Cao, Kun

2016-07-15

Iron(II,III) oxide (Fe{sub 3}O{sub 4}) nanoparticles have shown great promise in many magnetic-related applications such as magnetic resonance imaging, hyperthermia treatment, and targeted drug delivery. Nevertheless, these nanoparticles are vulnerable to oxidation and magnetization loss under ambient conditions, and passivation is usually required for practical applications. In this work, a home-built rotating fluidized bed (RFB) atomic layer deposition (ALD) reactor was employed to form dense and uniform nanoscale Al{sub 2}O{sub 3} passivation layers on Fe{sub 3}O{sub 4} nanoparticles. The RFB reactor facilitated the precursor diffusion in the particle bed and intensified the dynamic dismantling of soft agglomerates, exposing every surfacemore » reactive site to precursor gases. With the aid of in situ mass spectroscopy, it was found that a thicker fluidization bed formed by larger amount of particles increased the residence time of precursors. The prolonged residence time allowed more thorough interactions between the particle surfaces and the precursor gas, resulting in an improvement of the precursor utilization from 78% to nearly 100%, even under a high precursor feeding rate. Uniform passivation layers around the magnetic cores were demonstrated by both transmission electron microscopy and the statistical analysis of Al mass concentrations. Individual particles were coated instead of the soft agglomerates, as was validated by the specific surface area analysis and particle size distribution. The results of thermogravimetric analysis suggested that 5 nm-thick ultrathin Al{sub 2}O{sub 3} coatings could effectively protect the Fe{sub 3}O{sub 4} nanoparticles from oxidation. The x-ray diffraction patterns also showed that the magnetic core crystallinity of such passivated nanoparticles could be well preserved under accelerated oxidation conditions. The precise thickness control via ALD maintained the saturation magnetization at 66.7 emu/g with a 5 nm-thick Al{sub 2}O{sub 3} passivation layer. This good preservation of the magnetic properties with superior oxidation resistance will be beneficial for practical magnetic-based applications.« less

Influence of various chlorine additives on the partitioning of heavy metals during low-temperature two-stage fluidized bed incineration.

PubMed

Peng, Tzu-Huan; Lin, Chiou-Liang

2014-12-15

In this study, a pilot-scale low-temperature two-stage fluidized bed incinerator was evaluated for the control of heavy metal emissions using various chlorine (Cl) additives. Artificial waste containing heavy metals was selected to simulate municipal solid waste (MSW). Operating parameters considered included the first-stage combustion temperature, gas velocity, and different kinds of Cl additives. Results showed that the low-temperature two-stage fluidized bed reactor can be an effective system for the treatment of MSW because of its low NO(x), CO, HCl, and heavy metal emissions. The NO(x) and HCl emissions could be decreased by 42% and 70%, respectively. Further, the results showed that heavy metal emissions were reduced by bed material adsorption and filtration in the second stage. Regarding the Cl addition, although the Cl addition would reduce the metal capture in the first-stage sand bed, but those emitted metals could be effectively captured by the filtration of second stage. No matter choose what kind of additive, metal emissions in the low-temperature two-stage system are still lower than in a traditional high-temperature one-stage system. The results also showed that metal emissions depend not only on the combustion temperature but also on the physicochemical properties of the different metal species. Copyright © 2014 Elsevier Ltd. All rights reserved.

Balancing Near-Field Enhancement, Absorption, and Scattering for Effective Antenna-Reactor Plasmonic Photocatalysis.

PubMed

Li, Kun; Hogan, Nathaniel J; Kale, Matthew J; Halas, Naomi J; Nordlander, Peter; Christopher, Phillip

2017-06-14

Efficient photocatalysis requires multifunctional materials that absorb photons and generate energetic charge carriers at catalytic active sites to facilitate a desired chemical reaction. Antenna-reactor complexes are an emerging multifunctional photocatalytic structure where the strong, localized near field of the plasmonic metal nanoparticle (e.g., Ag) is coupled to the catalytic properties of the nonplasmonic metal nanoparticle (e.g., Pt) to enable chemical transformations. With an eye toward sustainable solar driven photocatalysis, we investigate how the structure of antenna-reactor complexes governs their photocatalytic activity in the light-limited regime, where all photons need to be effectively utilized. By synthesizing core@shell/satellite (Ag@SiO 2 /Pt) antenna-reactor complexes with varying Ag nanoparticle diameters and performing photocatalytic CO oxidation, we observed plasmon-enhanced photocatalysis only for antenna-reactor complexes with antenna components of intermediate sizes (25 and 50 nm). Optimal photocatalytic performance was shown to be determined by a balance between maximized local field enhancements at the catalytically active Pt surface, minimized collective scattering of photons out of the catalyst bed by the complexes, and minimal light absorption in the Ag nanoparticle antenna. These results elucidate the critical aspects of local field enhancement, light scattering, and absorption in plasmonic photocatalyst design, especially under light-limited illumination conditions.

Development of coal-feeding systems at the Morgantown Energy Research Center

NASA Technical Reports Server (NTRS)

Hobday, J. M.

1977-01-01

Systems for feeding crushed and pulverized coal into coal conversion reactor vessels are described. Pneumatic methods for feeding pulverized coal, slurry feeders, and coal pumps, methods for steam pickup, and a method for drying a water-coal slurry in a steam fluidized bed subsequent to feeding the coal into a reactor vessel are included.

Start-up of an anaerobic fluidized bed reactor treating synthetic carbohydrate rich wastewater.

PubMed

Yeshanew, Martha M; Frunzo, Luigi; Luongo, Vincenzo; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

2016-12-15

The present work studied the start-up process of a mesophilic (37 ± 2 °C) anaerobic fluidized bed reactor (AFBR) operated at a hydraulic retention time (HRT) of 20 days using synthetic carbohydrate rich wastewater. Anox Kaldness-K1 carriers were used as biofilm carrier material. The reactor performance and biofilm formation were evaluated during the process. The start-up process at lower liquid recirculation flow rate enhanced the biofilm formation and reactor performance. The organic substrate composition had a major impact on early colonization of methanogenic archaea onto the surface of the Kaldness carriers during the start-up process. Specific organic substrates favouring the growth of methanogenic archaea, such as acetate, are preferred in order to facilitate the subsequent biofilm formation and AFBR start-up. The supply of 'bio-available' nutrients and trace elements, in particular iron, had an important role on optimal methanogenic activity and speeding-up of the biofilm development on the Kaldness carriers. This paper provides possible strategies to optimize the various operational parameters that influence the initial biofilm formation and development in an AFBR and similar high rate anaerobic reactors, hence can be used to reduce the long time required for process start-up. Copyright © 2016 Elsevier Ltd. All rights reserved.

Wastewater treatment with submerged fixed bed biofilm reactor systems--design rules, operating experiences and ongoing developments.

PubMed

Schlegel, S; Koeser, H

2007-01-01

Wastewater treatment systems using bio-films that grow attached to a support media are an alternative to the widely used suspended growth activated sludge process. Different fixed growth biofilm reactors are commercially used for the treatment of municipal as well as industrial wastewater. In this paper a fairly new fixed growth biofilm system, the submerged fixed bed biofilm reactor (SFBBR), is discussed. SFBBRs are based on aerated submerged fixed open structured plastic media for the support of the biofilm. They are generally operated without sludge recirculation in order to avoid clogging of the support media and problems with the control of the biofilm. Reactor and process design considerations for these reactors are reviewed. Measures to ensure the development and maintenance of an active biofilm are examined. SFBBRs have been applied successfully to small wastewater treatment plants where complete nitrification but no high degree of denitrification is necessary. For the pre-treatment of industrial wastewater the use of SFBBRs is advantageous, especially in cases of wastewater with high organic loading or high content of compounds with low biodegradability. Performance data from exemplary commercial plants are given. Ongoing research and development efforts aim at achieving a high simultaneous total nitrogen (TN) removal of aerated SFBBRs and at improving the efficiency of TN removal in anoxic SFBBRs.

Applicability of fluidized bed reactor in recalcitrant compound degradation through advanced oxidation processes: a review.

PubMed

Tisa, Farhana; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

2014-12-15

Treatment of industrial waste water (e.g. textile waste water, phenol waste water, pharmaceutical etc) faces limitation in conventional treatment procedures. Advanced oxidation processes (AOPs) do not suffer from the limits of conventional treatment processes and consequently degrade toxic pollutants more efficiently. Complexity is faced in eradicating the restrictions of AOPs such as sludge formation, toxic intermediates formation and high requirement for oxidants. Increased mass-transfer in AOPs is an alternate solution to this problem. AOPs combined with Fluidized bed reactor (FBR) can be a potential choice compared to fixed bed or moving bed reactor, as AOP catalysts life-span last for only maximum of 5-10 cycles. Hence, FBR-AOPs require lesser operational and maintenance cost by reducing material resources. The time required for AOP can be minimized using FBR and also treatable working volume can be increased. FBR-AOP can process from 1 to 10 L of volume which is 10 times more than simple batch reaction. The mass transfer is higher thus the reaction time is lesser. For having increased mass transfer sludge production can be successfully avoided. The review study suggests that, optimum particle size, catalyst to reactor volume ratio, catalyst diameter and liquid or gas velocity is required for efficient FBR-AOP systems. However, FBR-AOPs are still under lab-scale investigation and for industrial application cost study is needed. Cost of FBR-AOPs highly depends on energy density needed and the mechanism of degradation of the pollutant. The cost of waste water treatment containing azo dyes was found to be US$ 50 to US$ 500 per 1000 gallons where, the cost for treating phenol water was US$ 50 to US$ 800 per 1000 gallons. The analysis for FBR-AOP costs has been found to depend on the targeted pollutant, degradation mechanism (zero order, 1st order and 2nd order) and energy consumptions by the AOPs. Copyright © 2014 Elsevier Ltd. All rights reserved.

II. Electrodeposition/removal of nickel in a spouted electrochemical reactor

PubMed Central

Grimshaw, Pengpeng; Calo, Joseph M.; Shirvanian, Pezhman A.; Hradil, George

2011-01-01

An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well. PMID:22039317

Apparatus for controlling molten core debris. [LMFBR

DOEpatents

Golden, M.P.; Tilbrook, R.W.; Heylmun, N.F.

1977-07-19

Disclosed is an apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed. 9 claims, 22 figures.

Influence of geometry on pressure and velocity distribution in packed-bed methanol steam reforming reactor

NASA Astrophysics Data System (ADS)

Ivanović, Ivana; Sedmak, Aleksandar; Milošević, Miloš; Cvetković, Ivana; Pohar, Andrej; Likozar, Blaž

2017-07-01

The main tasks of this research is to propose several changes in the packed bed micro methanol steam reformer geometry in order to ensure its performance. The reformer is an integral part of the existing indirect internal reforming high temperature PEMFC and most of its geometry is already defined. The space for remodeling is very limited.

Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

PubMed

Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

2016-06-01

Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). Copyright © 2016 Elsevier Ltd. All rights reserved.

Combined anaerobic digestion and photocatalytic treatment of distillery effluent in fluidized bed reactors focusing on energy conservation.

PubMed

Apollo, Seth; Aoyi, Ochieng

2016-09-01

Anaerobic digestion (AD) can remove substantial amount of organic load when applied in treating distillery effluent but it is ineffective in colour reduction. Conversely, photodegradation is effective in colour reduction but has high energy requirement. A study on the synergy of a combined AD and ultra violet (UV) photodegradation treatment of distillery effluent was carried out in fluidized bed reactors to evaluate pollution reduction and energy utilization efficiencies. The combined process improved colour removal from 41% to 85% compared to that of AD employed as a stand-alone process. An overall corresponding total organic carbon (TOC) reduction of 83% was achieved. The bioenergy production by the AD step was 14.2 kJ/g total organic carbon (TOC) biodegraded while UV lamp energy consumption was 0.9 kJ/mg TOC, corresponding to up to 100% colour removal. Electrical energy per order analysis for the photodegradation process showed that the bioenergy produced was 20% of that required by the UV lamp to photodegrade 1 m(3) of undiluted pre-AD treated effluent up to 75% colour reduction. It was concluded that a combined AD-UV system for treatment of distillery effluent is effective in organic load removal and can be operated at a reduced cost.

In situ magnetic resonance measurement of conversion, hydrodynamics and mass transfer during single- and two-phase flow in fixed-bed reactors.

PubMed

Gladden, L F; Alexander, P; Britton, M M; Mantle, M D; Sederman, A J; Yuen, E H L

2003-01-01

In recent years there has been increasing interest in applying magnetic resonance (MR) techniques in areas of engineering and chemical technology. The science that underpins many of these applications is the physics and chemistry of transport and reaction processes in porous materials. Key to the exploitation of MR methods will be our ability to demonstrate that MR yields information that cannot be obtained using conventional measurement techniques in engineering research. This article describes two case studies that highlight the power of MR to give new insights to chemical engineers. First, we demonstrate the application of MR techniques to explore both mass transfer and chemical conversion in situ within a fixed bed of catalyst, and we then use these data to identify the rate-controlling step of the chemical conversion. Second, we implement a rapid imaging technique to study the stability of the gas-liquid distribution in the low- and high-interaction two-phase flow regimes in a trickle-bed reactor.

Fixed bed pyrolysis of biomass solid waste for bio-oil

NASA Astrophysics Data System (ADS)

Islam, Mohammad Nurul; Ali, Mohamed Hairol Md; Haziq, Miftah

2017-08-01

Biomass solid waste in the form of rice husk particle is pyrolyzed in a fixed bed stainless steel pyrolysis reactor of 50 mm diameter and 50 cm length. The biomass solid feedstock is prepared prior to pyrolysis. The reactor bed is heated by means of a cylindrical heater of biomass source. A temperature of 500°C is maintained with an apperent vapor residence time of 3-5 sec. The products obtained are liquid bio-oil, solid char and gases. The liquid product yield is found to be 30% by weight of solid biomass feedstock while the solid product yield is found to be 35% by weight of solid biomass feedtock, the rest is gas. The bio-oil is a single-phase brownish color liquid of acrid smell. The heating value of the oil is determined to be 25 MJ/kg. The density and pH value are found to be 1.125 kg/m3 and 3.78 respectively.

Co-pyrolysis characteristics of sawdust and coal blend in TGA and a fixed bed reactor.

PubMed

Park, Dong Kyoo; Kim, Sang Done; Lee, See Hoon; Lee, Jae Goo

2010-08-01

Co-pyrolysis characteristics of sawdust and coal blend were determined in TGA and a fixed bed reactor. The yield and conversion of co-pyrolysis of sawdust and coal blend based on volatile matters are higher than those of the sum of sawdust and coal individually. Form TGA experiments, weight loss rate of sawdust and coal blend increases above 400 degrees C and additional weight loss was observed at 700 degrees C. In a fixed bed at isothermal condition, the synergy to produce more volatiles is appeared at 500-700 degrees C, and the maximum synergy exhibits with a sawdust blending ratio of 0.6 at 600 degrees C. The gas product yields remarkably increase at lower temperature range by reducing tar yield. The CO yield increases up to 26% at 400 degrees C and CH(4) yield increases up to 62% at 600 degrees C compared with the calculated value from the additive model. (c) 2010 Elsevier Ltd. All rights reserved.

Development of a gravity-independent wastewater bioprocessor for advanced life support in space

NASA Technical Reports Server (NTRS)

Nashashibi-Rabah, Majda; Christodoulatos, Christos; Korfiatis, George P.; Janes, H. W. (Principal Investigator)

2005-01-01

Operation of aerobic biological reactors in space is controlled by a number of challenging constraints, mainly stemming from mass transfer limitations and phase separation. Immobilized-cell packed-bed bioreactors, specially designed to function in the absence of gravity, offer a viable solution for the treatment of gray water generated in space stations and spacecrafts. A novel gravity-independent wastewater biological processor, capable of carbon oxidation and nitrification of high-strength aqueous waste streams, is presented. The system, consisting of a fully saturated pressurized packed bed and a membrane oxygenation module attached to an external recirculation loop, operated continuously for over one year. The system attained high carbon oxidation efficiencies often exceeding 90% and ammonia oxidation reaching approximately 60%. The oxygen supply module relies on hydrophobic, nonporous, oxygen selective membranes, in a shell and tube configuration, for transferring oxygen to the packed bed, while keeping the gaseous and liquid phases separated. This reactor configuration and operating mode render the system gravity-independent and suitable for space applications.

Porous stabilized beds, methods of manufacture thereof and articles comprising the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klausner, James F.; Mei, Renwei; Momen, Ayyoub Mehdizadeh

Disclosed herein is a method comprising disposing a first particle in a reactor; the first particle being a magnetic particle or a particle that can be influenced by a magnetic field, an electric field or a combination of an electrical field and a magnetic field; fluidizing the first particle in the reactor; applying a uniform magnetic field, a uniform electrical field or a combination of a uniform magnetic field and a uniform electrical field to the reactor; elevating the temperature of the reactor; and fusing the first particles to form a monolithic solid.

ENGINEERING APPLICATIONS OF ANALOG COMPUTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryant, L.T.; Janicke, M.J.; Just, L.C.

1963-10-31

Six experiments from the fields of reactor engineering, heat transfer, and dynamics are presented to illustrate the engineering applications of analog computers. The steps required for producing the analog solution are shown, as well as complete information for duplicating the solution. Graphical results are provided. The experiments include: deceleration of a reactor control rod, pressure variations through a packed bed, reactor kinetics over many decades with thermal feedback, a vibrating system with two degrees of freedom, temperature distribution in a radiating fin, temperature distribution in an infinite slab considering variable thermal properties, and iodine -xenon buildup in a reactor. (M.C.G.)

Immobilization of a Pleurotus ostreatus Laccase Mixture on Perlite and Its Application to Dye Decolourisation

PubMed Central

Salatino, Piero; Sannia, Giovanni

2014-01-01

In the present study, a crude laccase preparation from Pleurotus ostreatus was successfully immobilized on perlite, a cheap porous silica material, and tested for Remazol Brilliant Blue R (RBBR) decolourisation in a fluidized bed recycle reactor. Results showed that RBBR decolourisation is mainly due to enzyme action despite the occurrence of dye adsorption-related enzyme inhibition. Fine tuning of immobilization conditions allowed balancing the immobilization yield and the resulting rate of decolourisation, with the adsorption capacity of the solid biocatalyst. In the continuous lab scale reactor, a maximum conversion degree of 56.1% was achieved at reactor space-time of 4.2 h. Stability and catalytic parameters of the immobilized laccases were also assessed in comparison with the soluble counterparts, revealing an increase in stability, despite a reduction of the catalytic performances. Both effects are most likely ascribable to the occurrence of multipoint attachment phenomena. PMID:24895564

Current Development in Treatment and Hydrogen Energy Conversion of Organic Solid Waste

NASA Astrophysics Data System (ADS)

Shin, Hang-Sik

2008-02-01

This manuscript summarized current developments on continuous hydrogen production technologies researched in Korea advanced institute of science and technology (KAIST). Long-term continuous pilot-scale operation of hydrogen producing processes fed with non-sterile food waste exhibited successful results. Experimental findings obtained by the optimization processes of growth environments for hydrogen producing bacteria, the development of high-rate hydrogen producing strategies, and the feasibility tests for real field application could contribute to the progress of fermentative hydrogen production technologies. Three major technologies such as controlling dilution rate depending on the progress of acidogenesis, maintaining solid retention time independently from hydraulic retention time, and decreasing hydrogen partial pressure by carbon dioxide sparging could enhance hydrogen production using anaerobic leaching beds reactors and anaerobic sequencing batch reactors. These findings could contribute to stable, reliable and effective performances of pilot-scale reactors treating organic wastes.

Kr-85m activity as burnup measurement indicator in a pebble bed reactor based on ORIGEN2.1 Computer Simulation

NASA Astrophysics Data System (ADS)

Husnayani, I.; Udiyani, P. M.; Bakhri, S.; Sunaryo, G. R.

2018-02-01

Pebble Bed Reactor (PBR) is a high temperature gas-cooled reactor which employs graphite as a moderator and helium as a coolant. In a multi-pass PBR, burnup of the fuel pebble must be measured in each cycle by online measurement in order to determine whether the fuel pebble should be reloaded into the core for another cycle or moved out of the core into spent fuel storage. One of the well-known methods for measuring burnup is based on the activity of radionuclide decay inside the fuel pebble. In this work, the activity and gamma emission of Kr-85m were studied in order to investigate the feasibility of Kr-85m as burnup measurement indicator in a PBR. The activity and gamma emission of Kr-85 were estimated using ORIGEN2.1 computer code. The parameters of HTR-10 were taken as a case study in performing ORIGEN2.1 simulation. The results show that the activity revolution of Kr-85m has a good relationship with the burnup of the pebble fuel in each cycle. The Kr-85m activity reduction in each burnup step,in the range of 12% to 4%, is considered sufficient to show the burnup level in each cycle. The gamma emission of Kr-85m is also sufficiently high which is in the order of 1010 photon/second. From these results, it can be concluded that Kr-85m is suitable to be used as burnup measurement indicator in a pebble bed reactor.

Study on Characteristic of Temperature Coefficient of Reactivity for Plutonium Core of Pebbled Bed Reactor

NASA Astrophysics Data System (ADS)

Zuhair; Suwoto; Setiadipura, T.; Bakhri, S.; Sunaryo, G. R.

2018-02-01

As a part of the solution searching for possibility to control the plutonium, a current effort is focused on mechanisms to maximize consumption of plutonium. Plutonium core solution is a unique case in the high temperature reactor which is intended to reduce the accumulation of plutonium. However, the safety performance of the plutonium core which tends to produce a positive temperature coefficient of reactivity should be examined. The pebble bed inherent safety features which are characterized by a negative temperature coefficient of reactivity must be maintained under any circumstances. The purpose of this study is to investigate the characteristic of temperature coefficient of reactivity for plutonium core of pebble bed reactor. A series of calculations with plutonium loading varied from 0.5 g to 1.5 g per fuel pebble were performed by the MCNPX code and ENDF/B-VII library. The calculation results show that the k eff curve of 0.5 g Pu/pebble declines sharply with the increase in fuel burnup while the greater Pu loading per pebble yields k eff curve declines slighter. The fuel with high Pu content per pebble may reach long burnup cycle. From the temperature coefficient point of view, it is concluded that the reactor containing 0.5 g-1.25 g Pu/pebble at high burnup has less favorable safety features if it is operated at high temperature. The use of fuel with Pu content of 1.5 g/pebble at high burnup should be considered carefully from core safety aspect because it could affect transient behavior into a fatal accident situation.

Efficiency of wastewater treatment in SBR and IFAS-MBSBBR systems in specified technological conditions.

PubMed

Sytek-Szmeichel, K; Podedworna, J; Zubrowska-Sudol, M

2016-01-01

The objective of this study is to compare wastewater treatment effectiveness in sequencing batch reactor (SBR) and integrated fixed-film activated sludge-moving-bed sequencing batch biofilm reactor (IFAS-MBSBBR) systems in specific technological conditions. The comparison of these two technologies was based on the following assumptions, shared by both series, I and II: the reactor's active volume was 28 L; 8-hour cycle of reactor's work, with the same sequence and duration of its consecutive phases; and the dissolved oxygen concentration in the aerobic phases was maintained at a level of 3.0 mg O2/L. For both experimental series (I and II), comparable effectiveness of organic compound (chemical oxygen demand (COD)) removal, nitrification and biological phosphorus removal has been obtained at levels of 95.1%, 97% and 99%, respectively. The presence of the carrier improved the efficiency of total nitrogen removal from 86.3% to 91.7%. On the basis of monitoring tests, it has been found that the ratio of simultaneous denitrification in phases with aeration to the total efficiency of denitrification in the cycle was 1.5 times higher for IFAS-MBSBBR.

Assessment of start-up mechanisms for anaerobic fluidized bed reactor in series based on mathematical simulation

NASA Astrophysics Data System (ADS)

Sudibyo, Hanifrahmawan; Guntama, Dody; Budhijanto, Wiratni

2017-05-01

Anaerobic digestion is associated with long hydraulic residence time and hence leads to huge reactor volume, especially for high rate input to the reactor. To overcome this major drawback, one of the possibilities is optimizing the schemes of reactor configuration and start-up mechanisms. This study aimed to determine the most promising start-up mechanism for anaerobic digestion reactors in series, with respect to the shortest hydraulic residence time to reach the highest biogas production rate. The reactor to be studied is anaerobic fluidized bed reactor (AFBR) which is known as the most efficient reactor for high organic loading rate. Case to be studied is landfill leachate digestion. Although reactor optimization can be conducted experimentally, it could be expensive and time consuming. This study proposed the utilization of mathematical modeling to screen the possibilities towards the best options to be verified experimentally. Kinetic study of landfill leachate anaerobic digestion was first conducted to depict the rate of microbial growth and the rate of substrate consumption. Kinetics constants obtained from this batch experiment were then used in the mathematical model representing AFBR. Several mechanisms were simulated in this study. In the first mechanism, all digesters were started simultaneously. In the second mechanism, each digester was started until it achieved steady-state condition before the next digester was started. The third mechanism was start-up scenario for single reactor as opposed to the previous two mechanisms. These all three mechanisms were simulated for either one-through stream and recycling a portion of the reactor effluent. The mathematical simulation result was used to evaluate each mechanism based on hydraulic residence time required for all digesters in series to reach the steady-state condition, the extent of pollutant removal, and the rate of biogas production. In the need of high sCOD removal, the second mechanism emerged as the best one.

Exploratory study of several advanced nuclear-MHD power plant systems.

NASA Technical Reports Server (NTRS)

Williams, J. R.; Clement, J. D.; Rosa, R. J.; Yang, Y. Y.

1973-01-01

In order for efficient multimegawatt closed cycle nuclear-MHD systems to become practical, long-life gas cooled reactors with exit temperatures of about 2500 K or higher must be developed. Four types of nuclear reactors which have the potential of achieving this goal are the NERVA-type solid core reactor, the colloid core (rotating fluidized bed) reactor, the 'light bulb' gas core reactor, and the 'coaxial flow' gas core reactor. Research programs aimed at developing these reactors have progressed rapidly in recent years so that prototype power reactors could be operating by 1980. Three types of power plant systems which use these reactors have been analyzed to determine the operating characteristics, critical parameters and performance of these power plants. Overall thermal efficiencies as high as 80% are projected, using an MHD turbine-compressor cycle with steam bottoming, and slightly lower efficiencies are projected for an MHD motor-compressor cycle.

Deactivation of Zeolite Catalyst H-ZSM-5 during Conversion of Methanol to Gasoline: Operando Time- and Space-Resolved X-ray Diffraction.

PubMed

Rojo-Gama, Daniel; Mentel, Lukasz; Kalantzopoulos, Georgios N; Pappas, Dimitrios K; Dovgaliuk, Iurii; Olsbye, Unni; Lillerud, Karl Petter; Beato, Pablo; Lundegaard, Lars F; Wragg, David S; Svelle, Stian

2018-03-15

The deactivation of zeolite catalyst H-ZSM-5 by coking during the conversion of methanol to hydrocarbons was monitored by high-energy space- and time-resolved operando X-ray diffraction (XRD) . Space resolution was achieved by continuous scanning along the axial length of a capillary fixed bed reactor with a time resolution of 10 s per scan. Using real structural parameters obtained from XRD, we can track the development of coke at different points in the reactor and link this to a kinetic model to correlate catalyst deactivation with structural changes occurring in the material. The "burning cigar" model of catalyst bed deactivation is directly observed in real time.

Supercell Depletion Studies for Prismatic High Temperature Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Ortensi

2012-10-01

The traditional two-step method of analysis is not accurate enough to represent the neutronic effects present in the prismatic high temperature reactor concept. The long range coupling of the various regions in high temperature reactors poses a set of challenges that are not seen in either LWRs or fast reactors. Unlike LWRs, which exhibit large, localized effects, the dominant effects in PMRs are, for the most part, distributed over larger regions, but with lower magnitude. The 1-D in-line treatment currently used in pebble bed reactor analysis is not sufficient because of the 2-D nature of the prismatic blocks. Considerable challengesmore » exist in the modeling of blocks in the vicinity of reflectors, which, for current small modular reactor designs with thin annular cores, include the majority of the blocks. Additional challenges involve the treatment of burnable poisons, operational and shutdown control rods. The use of a large domain for cross section preparation provides a better representation of the neutron spectrum, enables the proper modeling of BPs and CRs, allows the calculation of generalized equivalence theory parameters, and generates a relative power distribution that can be used in compact power reconstruction. The purpose of this paper is to quantify the effects of the reflector, burnable poison, and operational control rods on an LEU design and to delineate an analysis approach for the Idaho National Laboratory. This work concludes that the use of supercells should capture these long-range effects in the preparation of cross sections and along with a set of triangular meshes to treat BPs, and CRs a high fidelity neutronics computation is attainable.« less

Removal of pharmaceuticals in conventionally treated wastewater by a polishing moving bed biofilm reactor (MBBR) with intermittent feeding.

PubMed

Tang, Kai; Ooi, Gordon T H; Litty, Klaus; Sundmark, Kim; Kaarsholm, Kamilla M S; Sund, Christina; Kragelund, Caroline; Christensson, Magnus; Bester, Kai; Andersen, Henrik R

2017-07-01

Previous studies have demonstrated that aerobic moving bed biofilm reactors (MBBRs) remove pharmaceuticals better than activated sludge. Thus we used a MBBR system to polish the effluent of an activated sludge wastewater treatment plant. To overcome that effluent contains insufficient organic matter to sustain enough biomass, the biofilm was intermittently fed with raw wastewater. The capacity of pharmaceutical degradation was investigated by spiking pharmaceuticals. Actual removal during treatment was assessed by sampling the inlets and outlets of reactors. The removal of the majority of pharmaceuticals was enhanced through the intermittent feeding of the MBBR. First-order rate constants for pharmaceutical removal, normalised to biomass, were significantly higher compared to other studies on activated sludge and suspended biofilms, especially for diclofenac, metoprolol and atenolol. Due to the intermittently feeding, degradation of diclofenac occurred with a half-life of only 2.1h and was thus much faster than any hitherto described wastewater bioreactor treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Utilization of moving bed biofilm reactor for industrial wastewater treatment containing ethylene glycol: kinetic and performance study.

PubMed

Hassani, Amir Hessam; Borghei, Seyed Mehdi; Samadyar, Hassan; Ghanbari, Bastam

2014-01-01

One of the requirements for environmental engineering, which is currently being considered, is the removal of ethylene glycol (EG) as a hazardous environmental pollutant from industrial wastewater. Therefore, in a recent study, a moving bed biofilm reactor (MBBR) was applied at pilot scale to treat industrial effluents containing different concentrations of EG (600, 800, 1200, and 1800 mg L-1 ). The removal efficiency and kinetic analysis of the system were examined at different hydraulic retention times of 6, 8, 10, and 12 h as well as influent chemical oxygen demand (COD) ranged between values of 1000 and 3000mg L-1. In minimum and maximum COD Loadings, the MBBR showed 95.1% and 60.7% removal efficiencies, while 95.9% and 66.2% EG removal efficiencies were achieved in the lowest and highest EG concentrations. The results of the reactor modelling suggested compliance of the well-known modified Stover-Kincannon model with the system.

A novel fast mass transfer anaerobic inner loop fluidized bed biofilm reactor for PTA wastewater treatment.

PubMed

Chen, Yingwen; Zhao, Jinlong; Li, Kai; Xie, Shitao

In this paper, a fast mass transfer anaerobic inner loop fluidized bed biofilm reactor (ILFBBR) was developed to improve purified terephthalic acid (PTA) wastewater treatment. The emphasis of this study was on the start-up mode of the anaerobic ILFBBR, the hydraulic loadings and the operation stability. The biological morphology of the anaerobic biofilm in the reactors was also analyzed. The anaerobic column could operate successfully for 46 days due to the pre-aerating process. The anaerobic column had the capacity to resist shock loadings and maintained a high stable chemical oxygen demand (COD) and terephthalic acid removal rates at a hydraulic retention time of 5-10 h, even under conditions of organic volumetric loadings as high as 28.8 kg COD·m(-3).d(-1). The scanning electron microscope analysis of the anaerobic carrier demonstrated that clusters of prokaryotes grew inside of pores and that the filaments generated by pre-aeration contributed to the anaerobic biofilm formation and stability.