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.

Phase shift method to estimate solids circulation rate in circulating fluidized beds

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

Ludlow, James Christopher; Panday, Rupen; Shadle, Lawrence J.

2013-01-01

While solids circulation rate is a critical design and control parameter in circulating fluidized bed (CFB) reactor systems, there are no available techniques to measure it directly at conditions of industrial interest. Cold flow tests have been conducted at NETL in an industrial scale CFB unit where the solids flow has been the topic of research in order to develop an independent method which could be applied to CFBs operating under the erosive and corrosive high temperatures and pressures of a coal fired boiler or gasifier. The dynamic responses of the CFB loop to modest modulated aeration flows in themore » return leg or standpipe were imposed to establish a periodic response in the unit without causing upset in the process performance. The resulting periodic behavior could then be analyzed with a dynamic model and the average solids circulation rate could be established. This method was applied to the CFB unit operated under a wide range of operating conditions including fast fluidization, core annular flow, dilute and dense transport, and dense suspension upflow. In addition, the system was operated in both low and high total solids inventories to explore the influence of inventory limiting cases on the estimated results. The technique was able to estimate the solids circulation rate for all transport circulating fluidized beds when operating above upper transport velocity, U{sub tr2}. For CFB operating in the fast fluidized bed regime (i.e., U{sub g}< U{sub tr2}), the phase shift technique was not successful. The riser pressure drop becomes independent of the solids circulation rate and the mass flow rate out of the riser does not show modulated behavior even when the riser pressure drop does.« less

Model-free adaptive control of supercritical circulating fluidized-bed boilers

DOEpatents

Cheng, George Shu-Xing; Mulkey, Steven L

2014-12-16

A novel 3-Input-3-Output (3.times.3) Fuel-Air Ratio Model-Free Adaptive (MFA) controller is introduced, which can effectively control key process variables including Bed Temperature, Excess O2, and Furnace Negative Pressure of combustion processes of advanced boilers. A novel 7-input-7-output (7.times.7) MFA control system is also described for controlling a combined 3-Input-3-Output (3.times.3) process of Boiler-Turbine-Generator (BTG) units and a 5.times.5 CFB combustion process of advanced boilers. Those boilers include Circulating Fluidized-Bed (CFB) Boilers and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.

PARTICLE FLOW, MIXING, AND CHEMICAL REACTION IN CIRCULATING FLUIDIZED BED ABSORBERS

EPA Science Inventory

A mixing model has been developed to simulate the particle residence time distribution (RTD) in a circulating fluidized bed absorber (CFBA). Also, a gas/solid reaction model for sulfur dioxide (SO2) removal by lime has been developed. For the reaction model that considers RTD dis...

Attrition and changes in size distribution of lime sorbents during fluidization in a circulating fluidized bed absorber. Double quarterly report, January 1--August 31, 1993

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

Lee, Sang-Kwun; Keener, T.C.; Cook, J.L.

1993-12-31

The experimental data of lime sorbent attrition obtained from attriton tests in a circulating fluidized bed absorber (CFBA) are represented. The results are interpreted as both the weight-based attrition rate and size-based attrition rate. The weight-based attrition rate constants are obtained from a modified second-order attrition model, incorporating a minimum fluidization weight, W{sub min}, and excess velocity. Furthermore, this minimum fluidization weight, or W{sub min} was found to be a function of both particle size and velocity. A plot of the natural log of the overall weight-based attrition rate constants (ln K{sub a}) for Lime 1 (903 MMD) at superficialmore » gas velocities of 2 m/s, 2.35 m/s, and 2.69 m/s and for Lime 2 (1764 MMD) at superficial gas velocities of 2 m/s, 3 m/s, 4 m/s and 5 m/s versus the energy term, 1/(U-U{sub mf}){sup 2}, yielded a linear relationship. And, a regression coefficient of 0.9386 for the linear regression confirms that K{sub a} may be expressed in Arrhenius form. In addition, an unsteady state population model is represented to predict the changes in size distribution of bed materials during fluidization. The unsteady state population model was verified experimentally and the solid size distribution predicted by the model agreed well with the corresponding experimental size distributions. The model may be applicable for the batch and continuous operations of fluidized beds in which the solids size reduction is predominantly resulted from attritions and elutriations. Such significance of the mechanical attrition and elutriation is frequently seen in a fast fluidized bed as well as in a circulating fluidized bed.« less

Experimental Study and CFD Simulation of a 2D Circulating Fluidized Bed

NASA Astrophysics Data System (ADS)

Kallio, S.; Guldén, M.; Hermanson, A.

Computational fluid dynamics (CFD) gains popularity in fluidized bed modeling. For model validation, there is a need of detailed measurements under well-defined conditions. In the present study, experiments were carried out in a 40 em wide and 3 m high 2D circulating fluidized bed. Two experiments were simulated by means of the Eulerian multiphase models of the Fluent CFD software. The vertical pressure and solids volume fraction profiles and the solids circulation rate obtained from the simulation were compared to the experimental results. In addition, lateral volume fraction profiles could be compared. The simulated CFB flow patterns and the profiles obtained from simulations were in general in a good agreement with the experimental results.

Morphologic and morphometric studies of impact craters in the northern plains of Mars

NASA Technical Reports Server (NTRS)

Barlow, N. G.

1993-01-01

Fresh impact craters in the northern plains of Mars display a variety of morphologic and morphometric properties. Ejecta morphologies range from radial to fluidized, interior features include central peaks and central pits, fluidized morphologies display a range of sinuosities, and depth-diameter ratios are being measured to determine regional variations. Studies of the martian northern plains over the past five years have concentrated in three areas: (1) determining correlations of ejecta morphologies with crater diameter, latitude, and underlying terrain; (2) determining variations in fluidized ejecta blanket sinuosity across the planet; and (3) measurement of depth-diameter ratios and determination of regional variations in this ratio.

ESTABLISHMENT OF AN ENVIRONMENTAL CONTROL TECHNOLOGY LABORATORY WITH A CIRCULATING FLUIDIZED-BED COMBUSTION SYSTEM

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

Wei-Ping Pan; Andy Wu; John T. Riley

This report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period October 1, 2004 through December 31, 2004. The following tasks have been completed. First, the renovation of the new Combustion Laboratory and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building have proceeded well. Second, the detailed design of supporting and hanging structures for the CFBC was completed. Third, the laboratory-scale simulated fluidized-bed facility was modified after completing a series of pretests. The two problems identified during the pretest were solved.more » Fourth, the carbonization of chicken waste and coal was investigated in a tube furnace and a Thermogravimetric Analyzer (TGA). The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter has been outlined in this report.« less

Fluidized bed regenerators for Brayton cycles

NASA Technical Reports Server (NTRS)

Nichols, L. D.

1975-01-01

A recuperator consisting of two fluidized bed regenerators with circulating solid particles is considered for use in a Brayton cycle. These fluidized beds offer the possibility of high temperature operation if ceramic particles are used. Calculations of the efficiency and size of fluidized bed regenerators for typical values of operating parameters were made and compared to a shell and tube recuperator. The calculations indicate that the fluidized beds will be more compact than the shell and tube as well as offering a high temperature operating capability.

COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS

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

Ibrahim, Essam A

2013-01-09

Details of numerical simulations of two-phase gas-solid turbulent flow in the riser section of Circulating Fluidized Bed Reactor (CFBR) using Computational Fluid Dynamics (CFD) technique are reported. Two CFBR riser configurations are considered and modeled. Each of these two riser models consist of inlet, exit, connecting elbows and a main pipe. Both riser configurations are cylindrical and have the same diameter but differ in their inlet lengths and main pipe height to enable investigation of riser geometrical scaling effects. In addition, two types of solid particles are exploited in the solid phase of the two-phase gas-solid riser flow simulations tomore » study the influence of solid loading ratio on flow patterns. The gaseous phase in the two-phase flow is represented by standard atmospheric air. The CFD-based FLUENT software is employed to obtain steady state and transient solutions for flow modulations in the riser. The physical dimensions, types and numbers of computation meshes, and solution methodology utilized in the present work are stated. Flow parameters, such as static and dynamic pressure, species velocity, and volume fractions are monitored and analyzed. The differences in the computational results between the two models, under steady and transient conditions, are compared, contrasted, and discussed.« less

A study on the Jordanian oil shale resources and utilization

NASA Astrophysics Data System (ADS)

Sakhrieh, Ahmad; Hamdan, Mohammed

2012-11-01

Jordan has significant oil shale deposits occurring in 26 known localities. Geological surveys indicate that the existing deposits underlie more than 60% of Jordan's territory. The resource consists of 40 to 70 billion tones of oil shale, which may be equivalent to more than 5 million tones of shale oil. Since the 1960s, Jordan has been investigating economical and environmental methods for utilizing oil shale. Due to its high organic content, is considered a suitable source of energy. This paper introduces a circulating fluidized bed combustor that simulates the behavior of full scale municipal oil shale combustors. The inside diameter of the combustor is 500 mm, the height is 3000 mm. The design of the CFB is presented. The main parameters which affect the combustion process are elucidated in the paper. The size of the laboratory scale fluidized bed reactor is 3 kW, which corresponds to a fuel-feeding rate of approximately 1.5 kg/h.

CFD analysis of hydrodynamic studies of a bubbling fluidized bed

NASA Astrophysics Data System (ADS)

Rao, B. J. M.; Rao, K. V. N. S.; Ranga Janardhana, G.

2018-03-01

Fluidization velocity is one of the most important parameter to characterize the hydrodynamic studies of fluidized bed asit determines different flow regimes. Computational Fluid Dynamics simulations are carriedfor a cylindrical bubbling fluidized bed with a static bed height 1m with 0.150m diameter of gasification chamber. The parameter investigated is fluidization velocity in range of 0.05m/s to 0.7m/s. Sand with density 2600kg/m3 and with a constant particle diameter of sand 385μm is employed for all the simulations. Simulations are conducted using the commercial Computational Fluid Dynamics software, ANSYS-FLUENT.The bubbling flow regime is appeared above the air inlet velocity of 0.2m/s. Bubbling character is increased with increase in inlet air velocities indicated by asymmetrical fluctuations of volume fractions in radial directions at different bed heights

CFD-DEM study of effect of bed thickness for bubbling fluidized beds

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

Tingwen, Li; Gopalakrishnan, Pradeep; Garg, Rahul

2011-10-01

The effect of bed thickness in rectangular fluidized beds is investigated through the CFD–DEM simulations of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and particle kinetic energy. Good two-dimensional (2D) flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional (3D) flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20–40 particle diameters. Comparison ofmore » velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.« less

Heat exchanger support apparatus in a fluidized bed

DOEpatents

Lawton, Carl W.

1982-01-01

A heat exchanger is mounted in the upper portion of a fluidized combusting bed for the control of the temperature of the bed. A support, made up of tubes, is extended from the perforated plate of the fluidized bed up to the heat exchanger. The tubular support framework for the heat exchanger has liquid circulated therethrough to prevent deterioration of the support.

Hybrid fluidized bed combuster

DOEpatents

Kantesaria, Prabhudas P.; Matthews, Francis T.

1982-01-01

A first atmospheric bubbling fluidized bed furnace is combined with a second turbulent, circulating fluidized bed furnace to produce heat efficiently from crushed solid fuel. The bed of the second furnace receives the smaller sizes of crushed solid fuel, unreacted limestone from the first bed, and elutriated solids extracted from the flu gases of the first bed. The two-stage combustion of crushed solid fuel provides a system with an efficiency greater than available with use of a single furnace of a fluidized bed.

Desulfurization characteristics of rapidly hydrated sorbents with various adhesive carrier particles for a semidry CFB-FGD system.

PubMed

You, Changfu; Li, Yuan

2013-03-19

Semidry flue gas desulfurization (FGD) experiments were conducted using rapidly hydrated sorbents with four different adhesive carrier particles: circulation ash from a circulating fluidized bed boiler (CFBB circulation ash), fly ash from the first electrical field of the electrostatic precipitator of a circulating fluidized bed boiler (CFBB ESP ash), fly ash from a chain boiler (chain boiler ash), and river sand smaller than 1 mm. The influences of various adhesive carrier particles and operating conditions on the desulfurization characteristics of the sorbents were investigated, including sprayed water, reaction temperature, and the ratio of calcium to sulfur (Ca/S). The experimental results indicated that the rapidly hydrated sorbents had better desulfurization characteristics by using adhesive carrier particles which possessed better pore, adhesion, and fluidization characteristics. The desulfurization efficiency of the system increased as the reaction temperature decreased, it improved from 35% to 90% as the mass flow rate of the sprayed water increased from 0 to 10 kg/h, and it increased from 65.6% to 82.7% as Ca/S increased from 1.0 to 2.0. Based on these findings, a new semidry circulating fluidized bed (CFB)-FGD system using rapidly hydrated sorbent was developed. Using the rapidly hydrated sorbent, this system uses a cyclone separator instead of an ESP or a bag filter to recycle the sorbent particles, thereby decreasing the system flow resistance, saving investment and operating costs of the solids collection equipment.

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.

Selective phenol methylation to 2,6-dimethylphenol in a fluidized bed of iron-chromium mixed oxide catalyst with o-cresol circulation.

PubMed

Zukowski, Witold; Berkowicz, Gabriela; Baron, Jerzy; Kandefer, Stanisław; Jamanek, Dariusz; Szarlik, Stefan; Wielgosz, Zbigniew; Zielecka, Maria

2014-01-01

2,6-dimethylphenol (2,6-DMP) is a product of phenol methylation, especially important for the plastics industry. The process of phenol methylation in the gas phase is strongly exothermic. In order to ensure good temperature equalization in the catalyst bed, the process was carried out using a catalyst in the form of a fluidized bed - in particular, the commercial iron-chromium catalyst TZC-3/1. Synthesis of 2,6-dimethylphenol from phenol and methanol in fluidized bed of iron-chromium catalyst was carried out and the fluidization of the catalyst was examined. Stable state of fluidized bed of iron-chromium catalyst was achieved. The measured velocities allowed to determine the minimum flow of reactants, ensuring introduction of the catalyst bed in the reactor into the state of fluidization. Due to a high content of o-cresol in products of 2,6-dimethylphenol synthesis, circulation in the technological node was proposed. A series of syntheses with variable amount of o-cresol in the feedstock allowed to determine the parameters of stationary states. A stable work of technological node with o-cresol circulation is possible in the temperature range of350-380°C, and o-cresolin/phenolin molar ratio of more than 0.48. Synthesis of 2,6-DMP over the iron-chromium catalyst is characterized by more than 90% degree of phenol conversion. Moreover, the O-alkylation did not occur (which was confirmed by GC-MS analysis). By applying o-cresol circulation in the 2,6-DMP process, selectivity of more than 85% degree of 2,6-DMP was achieved. The participation levels of by-products: 2,4-DMP and 2,4,6-TMP were low. In the optimal conditions based on the highest yield of 2,6-DMP achieved in the technological node applying o-cresol circulation, there are 2%mol. of 2,4-DMP and 6%mol. of 2,4,6-TMP in the final mixture, whereas 2,4,6-TMP can be useful as a chain stopper and polymer's molar mass regulator during the polymerization of 2,6-DMP.

Nonspherical particles in a pseudo-2D fluidized bed: Experimental study.

PubMed

Mahajan, Vinay V; Padding, Johan T; Nijssen, Tim M J; Buist, Kay A; Kuipers, J A M

2018-05-01

Fluidization is widely used in industries and has been extensively studied, both experimentally and theoretically, in the past. However, most of these studies focus on spherical particles while in practice granules are rarely spherical. Particle shape can have a significant effect on fluidization characteristics. It is therefore important to study the effect of particle shape on fluidization behavior in detail. In this study, experiments in pseudo-2D fluidized beds are used to characterize the fluidization of spherocylindrical (rod-like) Geldart D particles of aspect ratio 4. Pressure drop and optical measurement methods (Digital Image Analysis, Particle Image Velocimetry, Particle Tracking Velocimetry) are employed to measure bed height, particle orientation, particle circulation, stacking, and coordination number. The commonly used correlations to determine the pressure drop across a bed of nonspherical particles are compared to experiments. Experimental observations and measurements have shown that rod-like particles are prone to interlocking and channeling behavior. Well above the minimum fluidization velocity, vigorous bubbling fluidization is observed, with groups of interlocked particles moving upwards, breaking up, being thrown high in the freeboard region and slowly raining down as dispersed phase. At high flowrates, a circulation pattern develops with particles moving up through the center and down at the walls. Particles tend to orient themselves along the flow direction. © 2018 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers , 64: 1573-1590, 2018.

Nonspherical particles in a pseudo‐2D fluidized bed: Experimental study

PubMed Central

Mahajan, Vinay V.; Nijssen, Tim M. J.; Buist, Kay A.; Kuipers, J. A. M.

2018-01-01

Fluidization is widely used in industries and has been extensively studied, both experimentally and theoretically, in the past. However, most of these studies focus on spherical particles while in practice granules are rarely spherical. Particle shape can have a significant effect on fluidization characteristics. It is therefore important to study the effect of particle shape on fluidization behavior in detail. In this study, experiments in pseudo‐2D fluidized beds are used to characterize the fluidization of spherocylindrical (rod‐like) Geldart D particles of aspect ratio 4. Pressure drop and optical measurement methods (Digital Image Analysis, Particle Image Velocimetry, Particle Tracking Velocimetry) are employed to measure bed height, particle orientation, particle circulation, stacking, and coordination number. The commonly used correlations to determine the pressure drop across a bed of nonspherical particles are compared to experiments. Experimental observations and measurements have shown that rod‐like particles are prone to interlocking and channeling behavior. Well above the minimum fluidization velocity, vigorous bubbling fluidization is observed, with groups of interlocked particles moving upwards, breaking up, being thrown high in the freeboard region and slowly raining down as dispersed phase. At high flowrates, a circulation pattern develops with particles moving up through the center and down at the walls. Particles tend to orient themselves along the flow direction. © 2018 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 64: 1573–1590, 2018 PMID:29706659

Improvement of CFD Methods for Modeling Full Scale Circulating Fluidized Bed Combustion Systems

NASA Astrophysics Data System (ADS)

Shah, Srujal; Klajny, Marcin; Myöhänen, Kari; Hyppänen, Timo

With the currently available methods of computational fluid dynamics (CFD), the task of simulating full scale circulating fluidized bed combustors is very challenging. In order to simulate the complex fluidization process, the size of calculation cells should be small and the calculation should be transient with small time step size. For full scale systems, these requirements lead to very large meshes and very long calculation times, so that the simulation in practice is difficult. This study investigates the requirements of cell size and the time step size for accurate simulations, and the filtering effects caused by coarser mesh and longer time step. A modeling study of a full scale CFB furnace is presented and the model results are compared with experimental data.

Characterization of Combustion and Emission of Several Kinds of Herbaceous Biomass Pellets in a Circulating Fluidized Bed Combustor

NASA Astrophysics Data System (ADS)

Li, S. Y.; Teng, H. P.; Jiao, W. H.; Shang, L. L.; Lu, Q. G.

Characterizations of combustion and emission of four kinds of herbaceous biomass pellets were investigated in a 0.15 MWt circulating fluidized bed. Corn stalk, wheat stalk, cotton stalk and king grass, which are typical herbaceous biomass in China, were chosen for this study. Temperature profile, emission in flue gas and agglomeration were studied by changing the combustion temperature between 750°C and 880°C. The combustion efficiencies are in the range from 97.4% to 99.4%, which are relatively high due to the homogeneous temperature profiles and good circulating fluidization of bed material. Suitable combustion temperatures for the different herbaceous biomass are mainly depended on the emission and bed agglomeration. SO2 and HCl concentrations in flue gas are in direct proportion to the sulfur and chlorine contents of the herbaceous biomass. Agglomeration at the cyclone leg and the loop seal is the main reason for defluidization in the CFB combustor.

The combustion of large particles of char in bubbling fluidized beds: The dependence of Sherwood number and the rate of burning on particle diameter

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

Dennis, J.S.; Hayhurst, A.N.; Scott, S.A.

Particles of char derived from a variety of fuels (e.g., biomass, sewage sludge, coal, or graphite), with diameters in excess of {approx}1.5mm, burn in fluidized bed combustors containing smaller particles of, e.g., sand, such that the rate is controlled by the diffusion both of O{sub 2} to the burning solid and of the products CO and CO{sub 2} away from it into the particulate phase. It is therefore important to characterize these mass transfer processes accurately. Measurements of the burning rate of char particles made from sewage sludge suggest that the Sherwood number, Sh, increases linearly with the diameter ofmore » the fuel particle, d{sub char} (for d{sub char}>{approx}1.5mm). This linear dependence of Sh on d{sub char} is expected from the basic equation Sh=2{epsilon}{sub mf}(1+d{sub char}/2{delta}{sub diff})/{tau}, provided the thickness of the boundary layer for mass transfer, {delta}{sub diff}, is constant in the region of interest (d{sub char}>{approx}1.5mm). Such a dependence is not seen in the empirical equations currently used and based on the Frossling expression. It is found here that for chars made from sewage sludge (for d{sub char}>{approx}1.5mm), the thickness of the boundary layer for mass transfer in a fluidized bed, {delta}{sub diff}, is less than that predicted by empirical correlations based on the Frossling expression. In fact, {delta}{sub diff} is not more than the diameter of the fluidized sand particles. Finally, the experiments in this study indicate that models based on surface renewal theory should be rejected for a fluidized bed, because they give unrealistically short contact times for packets of fluidized particles at the surface of a burning sphere. The result is the new correlation Sh = 2{epsilon}{sub mf}/{tau} + (A{sub cush}/A{sub char})(d{sub char}/ {delta}{sub diff}) for the dependence of Sh on d{sub char}, the diameter of a burning char particle. This equation is based on there being a gas-cushion of fluidizing gas underneath a burning char particle; the implication of this correlation is that a completely new picture emerges for the combustion of a char particle in a hot fluidized bed. (author)« less

Relationship between fluid bed aerosol generator operation and the aerosol produced

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

Carpenter, R.L.; Yerkes, K.

1980-12-01

The relationships between bed operation in a fluid bed aerosol generator and aerosol output were studied. A two-inch diameter fluid bed aerosol generator (FBG) was constructed using stainless steel powder as a fluidizing medium. Fly ash from coal combustion was aerosolized and the influence of FBG operating parameters on aerosol mass median aerodynamic diameter (MMAD), geometric standard deviation (sigma/sub g/) and concentration was examined. In an effort to extend observations on large fluid beds to small beds using fine bed particles, minimum fluidizing velocities and elutriation constant were computed. Although FBG minimum fluidizing velocity agreed well with calculations, FBG elutriationmore » constant did not. The results of this study show that the properties of aerosols produced by a FBG depend on fluid bed height and air flow through the bed after the minimum fluidizing velocity is exceeded.« less

Modeling biomass gasification in circulating fluidized beds

NASA Astrophysics Data System (ADS)

Miao, Qi

In this thesis, the modeling of biomass gasification in circulating fluidized beds was studied. The hydrodynamics of a circulating fluidized bed operating on biomass particles were first investigated, both experimentally and numerically. Then a comprehensive mathematical model was presented to predict the overall performance of a 1.2 MWe biomass gasification and power generation plant. A sensitivity analysis was conducted to test its response to several gasifier operating conditions. The model was validated using the experimental results obtained from the plant and two other circulating fluidized bed biomass gasifiers (CFBBGs). Finally, an ASPEN PLUS simulation model of biomass gasification was presented based on minimization of the Gibbs free energy of the reaction system at chemical equilibrium. Hydrodynamics plays a crucial role in defining the performance of gas-solid circulating fluidized beds (CFBs). A 2-dimensional mathematical model was developed considering the hydrodynamic behavior of CFB gasifiers. In the modeling, the CFB riser was divided into two regions: a dense region at the bottom and a dilute region at the top of the riser. Kunii and Levenspiel (1991)'s model was adopted to express the vertical solids distribution with some other assumptions. Radial distributions of bed voidage were taken into account in the upper zone by using Zhang et al. (1991)'s correlation. For model validation purposes, a cold model CFB was employed, in which sawdust was transported with air as the fluidizing agent. A comprehensive mathematical model was developed to predict the overall performance of a 1.2 MWe biomass gasification and power generation demonstration plant in China. Hydrodynamics as well as chemical reaction kinetics were considered. The fluidized bed riser was divided into two distinct sections: (a) a dense region at the bottom of the bed where biomass undergoes mainly heterogeneous reactions and (b) a dilute region at the top where most of homogeneous reactions occur in gas phase. Each section was divided into a number of small cells, over which mass and energy balances were applied. Due to the high heating rate in circulating fluidized bed, the pyrolysis was considered instantaneous. A number of homogeneous and heterogeneous reactions were considered in the model. Mass transfer resistance was considered negligible since the reactions were under kinetic control due to good gas-solid mixing. The model is capable of predicting the bed temperature distribution along the gasifier, the concentration and distribution of each species in the vertical direction of the bed, the composition and lower heating value (LHV) of produced gas, the gasification efficiency, the overall carbon conversion and the produced gas production rate. A sensitivity analysis was performed to test its response to several gasifier operating conditions. The model sensitivity analysis showed that equivalence ratio (ER), bed temperature, fluidization velocity, biomass feed rate and moisture content had various effects on the gasifier performance. However, the model was more sensitive to variations in ER and bed temperature. The model was validated using the experimental results obtained from the demonstration plant. The reactor was operated on rice husk at various ERs, fluidization velocities and biomass feed rates. The model gave reasonable predictions. The model was also validated by comparing the simulation results with two other different size CFBBGs using different biomass feedstock, and it was concluded that the developed model can be applied to other CFBBGs using various biomass fuels and having comparable reactor geometries. A thermodynamic model was developed under ASPEN PLUS environment. Using the approach of Gibbs free energy minimization, the model was essentially independent of kinetic parameters. A sensitivity analysis was performed on the model to test its response to operating variables, including ER and biomass moisture content. The results showed that the ER has the most effect on the product gas composition and LHV. The simulation results were compared with the experimental data obtained from the demonstration plant. Keywords: Biomass gasification; Mathematical model; Circulating fluidized bed; Hydrodynamics; Kinetics; Sensitivity analysis; Validation; Equivalence ratio; Temperature; Feed rate; Moisture; Syngas composition; Lower heating value; Gasification efficiency; Carbon conversion

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)

Dynamic analysis of a circulating fluidized bed riser

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

Panday, Rupen; Shadle, Lawrence J.; Guenther, Chris

2012-01-01

A linear state model is proposed to analyze dynamic behavior of a circulating fluidized bed riser. Different operating regimes were attained with high density polyethylene beads at low and high system inventories. The riser was operated between the classical choking velocity and the upper transport velocity demarcating fast fluidized and transport regimes. At a given riser superficial gas velocity, the aerations fed at the standpipe were modulated resulting in a sinusoidal solids circulation rate that goes into the riser via L-valve. The state model was derived based on the mass balance equation in the riser. It treats the average solidsmore » fraction across the entire riser as a state variable. The total riser pressure drop was modeled using Newton’s second law of motion. The momentum balance equation involves contribution from the weight of solids and the wall friction caused by the solids to the riser pressure drop. The weight of solids utilizes the state variable and hence, the riser inventory could be easily calculated. The modeling problem boils down to estimating two parameters including solids friction coefficient and time constant of the riser. It has been shown that the wall friction force acts in the upward direction in fast fluidized regime which indicates that the solids were moving downwards on the average with respect to the riser wall. In transport regimes, the friction acts in the opposite direction. This behavior was quantified based on a sign of Fanning friction factor in the momentum balance equation. The time constant of the riser appears to be much higher in fast fluidized regime than in transport conditions.« less

Gas-solid fluidized bed reactors: Scale-up, flow regimes identification and hydrodynamics

NASA Astrophysics Data System (ADS)

Zaid, Faraj Muftah

This research studied the scale-up, flow regimes identification and hydrodynamics of fluidized beds using 6-inch and 18- inch diameter columns and different particles. One of the objectives was to advance the scale-up of gas-solid fluidized bed reactors by developing a new mechanistic methodology for hydrodynamic similarity based on matching the radial or diameter profile of gas phase holdup, since gas dynamics dictate the hydrodynamics of these reactors. This has been successfully achieved. However, the literature reported scale-up methodology based on matching selected dimensionless groups was examined and it was found that it was not easy to match the dimensionless groups and hence, there was some deviation in the hydrodynamics of the studied two different fluidized beds. A new technique based on gamma ray densitometry (GRD) was successfully developed and utilized to on-line monitor the implementation of scale-up, to identify the flow regime, and to measure the radial or diameter profiles of gas and solids holdups. CFD has been demonstrated as a valuable tool to enable the implementation of the newly developed scale-up methodology based on finding the conditions that provide similar or closer radial profile or cross sectional distribution of the gas holdup. As gas velocity increases, solids holdup in the center region of the column decreases in the fully developed region of both 6 inch and 18 inch diameter columns. Solids holdup increased with the increase in the particles size and density. Upflowing particles velocity increased with the gas velocity and became steeper at high superficial gas velocity at all axial heights where the center line velocity became higher than that in the wall region. Smaller particles size and lower density gave larger upflowing particles velocity. Minimum fluidization velocity and transition velocity from bubbly to churn turbulent flow regimes were found to be lower in 18 inch diameter column compared to those obtained in 6 inch diameter column. Also the absolute fluctuation of upflowing particles velocity multiplied by solids holdups vś 3ś as one of the terms for solids mass flux estimation was found to be larger in 18-inch diameter column than that in 6-inch diameter column using same particles size and density.

Simulation of biomass-steam gasification in fluidized bed reactors: Model setup, comparisons and preliminary predictions.

PubMed

Yan, Linbo; Lim, C Jim; Yue, Guangxi; He, Boshu; Grace, John R

2016-12-01

A user-defined solver integrating the solid-gas surface reactions and the multi-phase particle-in-cell (MP-PIC) approach is built based on the OpenFOAM software. The solver is tested against experiments. Then, biomass-steam gasification in a dual fluidized bed (DFB) gasifier is preliminarily predicted. It is found that the predictions agree well with the experimental results. The bed material circulation loop in the DFB can form automatically and the bed height is about 1m. The voidage gradually increases along the height of the bed zone in the bubbling fluidized bed (BFB) of the DFB. The U-bend and cyclone can separate the syngas in the BFB and the flue gas in the circulating fluidized bed. The concentration of the gasification products is relatively higher in the conical transition section, and the dry and nitrogen-free syngas at the BFB outlet is predicted to be composed of 55% H 2 , 20% CO, 20% CO 2 and 5% CH 4 . Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Numerical study of rice husk and coal co-combustion characteristics in a circulating fluidized bed

NASA Astrophysics Data System (ADS)

Wang, Zuomin; Li, Jiuru

2018-02-01

This paper discussed the rationality of coal and rice husk co-combustion. Using ICEM software, a two-dimensional model of the riser has been established for circulating fluidized bed experimental table. Using Fluent software, numerical simulation has been made for the combustion reaction of different proportions of rice husk mixed with coal. The results show that, with the increase of rice husk ratio, both the combustion temperature and the amount of nitrogen oxides decrease and the effect is gradually reduced. In this simulation, the rice husks occupying about 30% is a reasonable proportion.

Co-firing of paper mill sludge and coal in an industrial circulating fluidized bed boiler.

PubMed

Tsai, Meng-Yuan; Wu, Keng-Tung; Huang, Chin-Cheng; Lee, Hom-Ti

2002-01-01

Co-firing of coal and paper mill sludge was conducted in a 103 MWth circulating fluidized bed boiler to investigate the effect of the sludge feeding rate on emissions of SOx, NOx, and CO. The preliminary results show that emissions of SOx and Nx decrease with increasing sludge feeding rate, but CO shows the reverse tendency due to the decrease in combustion temperature caused by a large amount of moisture in the sludge. All emissions met the local environmental requirements. The combustion ashes could be recycled as feed materials in the cement manufacturing process.

Model-free adaptive control of advanced power plants

DOEpatents

Cheng, George Shu-Xing; Mulkey, Steven L.; Wang, Qiang

2015-08-18

A novel 3-Input-3-Output (3.times.3) Model-Free Adaptive (MFA) controller with a set of artificial neural networks as part of the controller is introduced. A 3.times.3 MFA control system using the inventive 3.times.3 MFA controller is described to control key process variables including Power, Steam Throttle Pressure, and Steam Temperature of boiler-turbine-generator (BTG) units in conventional and advanced power plants. Those advanced power plants may comprise Once-Through Supercritical (OTSC) Boilers, Circulating Fluidized-Bed (CFB) Boilers, and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.

Devolatilization of oil sludge in a lab-scale bubbling fluidized bed.

PubMed

Liu, Jianguo; Jiang, Xiumin; Han, Xiangxin

2011-01-30

Devolatilization of oil sludge pellets was investigated in nitrogen and air atmosphere in a lab-scale bubbling fluidized bed (BFB). Devolatilization times were measured by the degree of completion of the evolution of the volatiles for individual oil sludge pellets in the 5-15 mm diameter range. The influences of pellet size, bed temperature and superficial fluidization velocity on devolatilization time were evaluated. The variation of devolatilization time with particle diameter was expressed by the correlation, τ(d) = Ad(p)(N). The devolatilization time to pellet diameter curve shows nearly a linear increase in nitrogen, whereas an exponential increase in air. No noticeable effect of superficial fluidization velocity on devolatilization time in air atmosphere was observed. The behavior of the sludge pellets in the BFB was also focused during combustion experiments, primary fragmentation (a micro-explosive combustion phenomenon) was observed for bigger pellets (>10mm) at high bed temperatures (>700 °C), which occurred towards the end of combustion and remarkably reduce the devolatilization time of the oil sludge pellet. The size analysis of bed materials and fly ash showed that entire ash particle was entrained or elutriated out of the BFB furnace due to the fragile structure of oil sludge ash particles. Copyright © 2010 Elsevier B.V. All rights reserved.

Overall Heat Transfer Coefficients for a Horizontal Cylinder in a Fluidized Bed.

DTIC Science & Technology

1984-04-01

The distribution system is composed of 2 in. PVC pipe and fittings arranged in a convenient air-tight geometry. Pressure regulators, pressure gauges...uniform fluidization. After i£ A_ 4 passing through the beads, the air is exhausted to the outside by means of galvanized duct work. Fluidized Bed...design is the matching with the copper cylinder of outer diameters, the fastening with recessed set screws , their length and the material selection. In

Attrition of lime sorbents during fluidization in a circulating fluidized bed absorber

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

Lee, Sang Kwun; Keener, T.C.; Jiang, Xiaolin

1993-11-01

The experimental data of lime sorbent attrition obtained from mechanical and thermal attrition tests in a circulating fluidized bed absorber (CFBA) are represented. The results indicate that the predominant attrition mechanism during lime fluidization is surface abrasion due to collisions of the parent solids in a bed. Attrition of lime at higher temperatures decreased due to its hardened properties with rising temperature, while such solids as limestone become more attritable by the crepitation resulting from the increased internal pressure. With an introduction of the minimum weight of parent solids, the attrition rate of lime in a CFBA has a first-ordermore » dependency with respect to time. The attrition rate constant is expressed in an Arrhenius form, using the kinetic model which relates the attrition rate to the gas properties such as temperature and molecular weight and the geometry of the fluidized bed as well as the fluidization velocity. The experimental data obtained from these tests in a CFBA agree well with the attrition model, and the model indicates trends due to increased temperature considering thermal attrition. From the model the attrition activation energy, E[sub a] and k[sub o], can be obtained as E[sub a] = 3.383 [times] 10[sup [minus]3] kJ/kg and k[sub o] = 1.29 [times] 10[sup [minus]4]s[sup [minus]1], Comparisons of the mechanical and thermal attrition data obtained experimentally with the theoretical values computed with the attrition activation energy, E[sub a] and k[sub o], are in good agreement, and thus the results may be applicable to lime attrition in a fluidized bed.« less

Jet penetration into a riser operated in dense suspension upflow: experimental and model comparisons

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

Shadle, L.J.; Ludlow, C.J.; Spenik, J.L.

2008-05-13

Solids tracers were used to characterize the penetration of a gas-solids jet directed toward the center of the 0.3-m diameter, circulating fluidized bed (CFB) riser. The penetration was measured by tracking phosphorescent particles illuminated immediately prior to injection into the riser. Photosensors and piezoelectric detectors were traversed across the radius of the riser at various axial positions to detect the phosphorescent jet material and particles traveling in the radial direction. Local particle velocities were measured at various radial positions, riser heights, and azimuthal angles using an optical fiber probe. Four (4) variables were tested including the jet velocity, solids feedmore » rate into the jet, the riser velocity, and overall CFB circulation rate over 8 distinct test cases with the central, or base case, repeated each time the test series was conducted. In addition to the experimental measurements made, the entire riser with a side feed jet of solids was simulated using the Eulerian-Eulerian computer model MFIX.« less

An experimental study of the transient regime to fluidized chimney in a granular medium

NASA Astrophysics Data System (ADS)

Philippe, Pierre; Mena, Sarah; Brunier-Coulin, Florian; Curtis, Jennifer

2017-06-01

Localized fluidization within a granular packing along an almost cylindrical chimney is observed when an upward fluid-flow, injected through a small port diameter, exceeds a critical flow-rate. Once this threshold reached, a fluidized area is first initiated in the close vicinity of the injection hole before gradually growing upward to the top surface of the granular layer. In this work, we present an experimental investigation specifically dedicated to the kinetics of chimney fluidization in an immersed granular bed. Two different transient regimes are identified depending on wether the expansion of the fluidized area is rather fast and regular, reaching the final chimney state typically in less than 10 seconds, or, on the contrary, slow and very progressively accelerated, giving rise to transient duration up to 1 hour or even more. Some systematic investigations allow to propose several empirical scaling relations for the kinetics of chimney fluidization in the fast regular regime.

Abatement of N{sub 2}O emissions from circulating fluidized bed combustion through afterburning

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

Gustavsson, L.; Leckner, B.

1995-04-01

A method for the abatement of N{sub 2}O emission from fluidized bed combustion has been investigated. The method consists of burning a secondary fuel after the normal circulating fluidized bed combustor. Liquefied petroleum gas (LPG), fuel oil, pulverized coal, and wood, as well as sawdust, were used as the secondary fuel. Experiments showed that the N{sub 2}O emission can be reduced by 90% or more by this technique. The resulting N{sub 2}O emission was principally a function of the gas temperature achieved in the afterburner and independent of afterburning fuel, but the amount of air in the combustion gases frommore » the primary combustion also influences the results. No negative effects on sulfur capture or on NO or CO emissions were recorded. In the experiments, the primary cyclone of the fluidized bed boiler was used for afterburning. If afterburning is implemented in a plant optimized for this purpose, an amount of secondary fuel corresponding to 10% of the total energy input should remove practically all N{sub 2}O. During the present experiments the secondary fuel consumption was greater than 10% of the total energy input due to various losses.« less

NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

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

Keith, Raymond E.; Heller, Thomas J.; Bush, Stuart A.

1991-01-01

This Annual Report on Colorado-Ute Electric Association's NUCLA Circulating Fluidized Bed (CFB) Demonstration Program covers the period from February 1987 through December 1988. The outline for presentation in this report includes a summary of unit operations along with individual sections covering progress in study plan areas that commenced during this reporting period. These include cold-mode shakedown and calibration, plant commercial performance statistics, unit start-up (cold), coal and limestone preparation and handling, ash handling system performance and operating experience, tubular air heater, baghouse operation and performance, materials monitoring, and reliability monitoring. During this reporting period, the coal-mode shakedown and calibration planmore » was completed. (VC)« less

The role of membrane fluidization in the gel-assisted formation of giant polymersomes

DOE PAGES

Greene, Adrienne C.; Henderson, Ian M.; Gomez, Andrew; ...

2016-07-13

Polymersomes are being widely explored as synthetic analogs of lipid vesicles based on their enhanced stability and potential uses in a wide variety of applications in (e.g., drug delivery, cell analogs, etc.). Controlled formation of giant polymersomes for use in membrane studies and cell mimetic systems, however, is currently limited by low-yield production methodologies. Here, we describe for the first time, how the size distribution of giant poly(ethylene glycol)-poly(butadiene) (PEO-PBD) polymersomes formed by gel-assisted rehydration may be controlled based on membrane fluidization. We first show that the average diameter and size distribution of PEO-PBD polymersomes may be readily increased bymore » increasing the temperature of the rehydration solution. Further, we describe a correlative relationship between polymersome size and membrane fluidization through the addition of sucrose during rehydration, enabling the formation of PEO-PBD polymersomes with a range of diameters, including giant-sized vesicles (>100 μm). This correlative relationship suggests that sucrose may function as a small molecule fluidizer during rehydration, enhancing polymer diffusivity during formation and increasing polymersome size. Altogether the ability to easily regulate the size of PEO-PBD polymersomes based on membrane fluidity, either through temperature or fluidizers, has broadly applicability in areas including targeted therapeutic delivery and synthetic biology.« less

Prospects for using the technology of circulating fluidized bed for technically refitting Russian thermal power stations

NASA Astrophysics Data System (ADS)

Ryabov, G. A.; Folomeev, O. M.; Litun, D. S.; Sankin, D. A.; Dmitryukova, I. G.

2009-01-01

The present state and development of circulating fluidized bed (CFB) technology around the world are briefly reviewed. Questions of increasing the capacity of single boiler units and raising the parameters of steam are discussed. CFB boilers for 225- and 330-MW power units are described and their parameters are estimated as applied to the conditions of firing different Russian fuels. Indicators characterizing CFB boilers and pulverized-coal boilers are given. Capital outlays and operational costs for new coal-fired units are compared, and the results from this comparison are used to show the field of the most promising use of the CFB technology during technical refitting of Russian thermal power stations.

The local heat transfer mathematical model between vibrated fluidized beds and horizontal tubes

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

Zhu, Xuejun; College of Biology and Chemical Engineering, Panzhihua University, Panzhihua 617000; Ye, Shichao

2008-05-15

A dimensionless mathematical model is proposed to predict the local heat transfer coefficients between vibrated fluidized beds and immersed horizontal tubes, and the effects of the thickness of gas film and the contact time of particle packets are well considered. Experiments using the glass beads (the average diameter bar d{sub p}=1.83mm) were conducted in a two-dimensional vibrated fluidized bed (240 mm x 80 mm). The local heat transfer law between vibrated fluidized bed and horizontal tube surface has been investigated. The results show that the values of theoretical prediction are in good agreement with experimental data, so the model ismore » able to predict the local heat transfer coefficients between vibrated fluidized beds and immersed horizontal tubes reasonably well, and the error is in range of {+-}15%. The results can provide references for future designing and researching on the vibrated fluidized beds with immersed horizontal tubes. (author)« less

The study of solid circulation rate in a compartmented fluidized bed gasifier (CFBG)

NASA Astrophysics Data System (ADS)

Wee, S. K.; Pok, Y. W.; Law, M. C.; Lee, V. C. C.

2016-06-01

Biomass waste has been abundantly available in Malaysia since the booming of palm oil industry. In order to tackle this issue, gasification is seen a promising technology to convert waste into energy. In view of the heat requirement for endothermic gasification reaction as well as the complex design and operation of multiple fluidized beds, compartmented fluidized bed gasifier (CFBG) with the combustor and the gasifier as separate compartments is proposed. As such, solid circulation rate (SCR) is one of the essential parameters for steady gasification and combustion to be realized in their respective compartments. Experimental and numerical studies (CFD) on the effect of static bed height, main bed aeration, riser aeration and v-valve aeration on SCR have been conducted in a cold- flow CFBG model with only river sand as the fluidizing medium. At lower operating range, the numerical simulations under-predict the SCR as compared to that of the experimental results. Also, it predicts slightly different trends over the range. On the other hand, at higher operating range, the numerical simulations are able to capture those trends as observed in the experimental results at the lower operating range. Overall, the numerical results compare reasonably well with that of the experimental works.

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.

Translocation and toxicity assessment of heavy metals from circulated fluidized-bed combustion of oil shale in Huadian, China.

PubMed

Luan, Jingde; Li, Aimin; Su, Tong; Li, Xuan

2009-07-30

Oil shale and fly ash collected from two thermal power plants located in Huadian, the northeast city of China were subjected to fraction distribution, translocation regularity and toxicity assessment to provide preliminary assessment of suitability for land application. By Tessier sequential extraction, the results showed that Ni, Cr, Pb and Zn were mostly bounded with iron-manganese and organic bound in oil shale, but Cu and Cd were mostly associated with iron-manganese bound and residue fraction. Through circulated fluidized-bed combustion, high concentration of heavy metals (Cu, Cd, Ni, Cr, Pb, and Zn) was found in iron-manganese bound and residue fraction in fly ash. There was accumulation of all studied metals except Ni and Cr in fly ash and translocation mass of metals were as follows: Pb>Zn>Cu>Cd during circulated fluidized-bed combustion. Fly ash was contaminated with Cd higher than the pollution concentration limits listed in GB15168-1995, China. This work demonstrated that it was unadvisable way to carry out landfill without any treatment. By means of STI model, toxicity assessment of heavy metals was carried out to show that there was notable increase in toxicity from oil shale to fly ash.

Fluidized bed heat exchanger utilizing angularly extending heat exchange tubes

DOEpatents

Talmud, Fred M.; Garcia-Mallol, Juan-Antonio

1980-01-01

A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided and includes a steam drum disposed adjacent the fluidized bed and a series of tubes connected at one end to the steam drum. A portion of the tubes are connected to a water drum and in the path of the air and the gaseous products of combustion exiting from the bed. Another portion of the tubes pass through the bed and extend at an angle to the upper surface of the bed.

Internal dust recirculation system for a fluidized bed heat exchanger

DOEpatents

Gamble, Robert L.; Garcia-Mallol, Juan A.

1981-01-01

A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided in a heat exchange relation to the bed and includes a steam drum disposed adjacent the bed and a tube bank extending between the steam drum and a water drum. The tube bank is located in the path of the effluent gases exiting from the bed and a baffle system is provided to separate the solid particulate matter from the effluent gases. The particulate matter is collected and injected back into the fluidized bed.

Effect of distributor on performance of a continuous fluidized bed dryer

NASA Astrophysics Data System (ADS)

Yogendrasasidhar, D.; Srinivas, G.; Pydi Setty, Y.

2018-03-01

Proper gas distribution is very important in fluidized bed drying in industrial practice. Improper distribution of gas may lead to non-idealities like channeling, short circuiting and accumulation which gives rise to non-uniform quality of dried product. Gas distribution depends on the distributor plate used. Gas distribution mainly depends on orifice diameter, number of orifices and opening area of the distributor plate. Small orifice diameter leads to clogging, and a large orifice diameter gives uneven distribution of gas. The present work involves experimental studies using different distributor plates and simulation studies using ASPEN PLUS steady state simulator. The effect of various parameters such as orifice diameter, number of orifices and the opening area of the distributor plate on the performance of fluidized bed dryer have been studied through simulation and experimentation. Simulations were carried out (i) with increasing air inlet temperature to study the characteristics of solid temperature and moisture in outlet (ii) with increasing orifice diameter and (iii) with increase in number orifices to study the solid outlet temperature profiles. It can be observed from the simulation that, an increase in orifice diameter and number orifices increases solid outlet temperature upto certain condition and then after there is no effect with further increase. Experiments were carried out with increasing opening area (3.4 to 42%) in the form of increasing orifice diameter keeping the number of orifices constant and increasing number of orifices of the distributor plate keeping the orifice diameter constant. It can be seen that the drying rate and solid outlet temperature increase upto certain condition and then after with further increase in the orifice diameter and number of orifices, the change in the drying rate and solid outlet temperature observed is little. The optimum values of orifice diameter and number of orifices from experimentation are found to be 5 mm and 60 (22% opening area).

Factors influencing the nitrification efficiency of fluidized bed filter with a plastic bead medium

USGS Publications Warehouse

Sandu, S.I.; Boardman, G.D.; Watten, B.J.; Brazil, B.L.

2002-01-01

The performance of fluidized bed nitrification filters charged with 2 ?? 4 ABS plastic beads (specific gravity 1.06) was evaluated. Three unique bed-height to diameter ratios were established, in triplicate, using column diameters of 12.7, 15.2 and 17.8 cm. Filters received water spiked with recycled nutrients and ammonia (TAN), from one of the three 500 1 feed tank system. With daily ammonia loading fixed at 8.6 g per system, TAN removal increased with column diameter at each of four tests hydraulic loading rates (6, 8, 10 and 12 Lpm). TAN in recirculated water (influent) rose from 0.5 to 1.0 mg/1 as ammonia loading increased from 180 mg/m2-day to 360 mg/m2-day. When hydraulic loading was fixed at 12 Lpm, TAN removal (%) was maximized with ammonia loadings ranging from 225 to 270 mg/m2-day. Biofilm thickness increased with ammonia loading, but decreased with increased hydraulic loading rates. Fluidized beds of ABS plastic beads were effective in reducing energy costs (head loss) of water treatment. ?? 2002 Elsevier Science B.V. All rights reserved.

Method for applying pyrolytic carbon coatings to small particles

DOEpatents

Beatty, Ronald L.; Kiplinger, Dale V.; Chilcoat, Bill R.

1977-01-01

A method for coating small diameter, low density particles with pyrolytic carbon is provided by fluidizing a bed of particles wherein at least 50 per cent of the particles have a density and diameter of at least two times the remainder of the particles and thereafter recovering the small diameter and coated particles.

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

High-Resolution Simulations of Gas-Solids Jet Penetration Into a High Density Riser Flow

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

Li, Tingwen

2011-05-01

High-resolution simulations of a gas-solids jet in a 0.3 m diameter and 15.9 m tall circulating fluidized bed (CFB) riser were conducted with the open source software-MFIX. In the numerical simulations, both gas and solids injected through a 1.6 cm diameter radial-directed tube 4.3 m above the bottom distributor were tracked as tracers, which enable the analysis of the characteristics of a two-phase jet. Two jetting gas velocities of 16.6 and 37.2 m/s were studied with the other operating conditions fixed. Reasonable flow hydrodynamics with respect to overall pressure drop, voidage, and solids velocity distributions were predicted. Due to themore » different dynamic responses of gas and particles to the crossflow, a significant separation of gas and solids within the jet region was predicted for both cases. In addition, the jet characteristics based on tracer concentration and tracer mass fraction profiles at different downstream levels are discussed. Overall, the numerical predictions compare favorably to the experimental measurements made at NETL.« less

Continuous fluidized-bed contactor with recycle of sorbent

DOEpatents

Scott, Charles D.; Petersen, James N.; Davison, Brian H.

1996-01-01

A continuous fluidized-bed contactor containing sorbent particles is used to remove solutes from liquid solvents. As the sorbent particles, for example gel beads, sorb the solute, for example metal ion species, the sorbent particles tend to decrease in diameter. These smaller loaded sorbent particles rise to the top of the contactor, as larger sorbent particles remain at the bottom of the contactor as a result of normal hydraulic forces. The smaller loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor. Alternatively, the loaded sorbent particles may also slightly increase in diameter, or exhibit no change in diameter but an increase in density. As a result of normal hydraulic forces the larger loaded sorbent particles fall to the bottom of the contactor. The larger loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor.

Continuous fluidized-bed contactor with recycle of sorbent

DOEpatents

Scott, C.D.; Petersen, J.N.; Davison, B.H.

1996-07-09

A continuous fluidized-bed contactor containing sorbent particles is used to remove solutes from liquid solvents. As the sorbent particles, for example gel beads, sorb the solute, for example metal ion species, the sorbent particles tend to decrease in diameter. These smaller loaded sorbent particles rise to the top of the contactor, and larger sorbent particles remain at the bottom of the contactor as a result of normal hydraulic forces. The smaller loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor. Alternatively, the loaded sorbent particles may also slightly increase in diameter, or exhibit no change in diameter but an increase in density. As a result of normal hydraulic forces the larger loaded sorbent particles fall to the bottom of the contactor. The larger loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor. 8 figs.

Fouling reduction characteristics of a no-distributor-fluidized-bed heat exchanger for flue gas heat recovery

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

Jun, Y.D.; Lee, K.B.; Islam, S.Z.

2008-07-01

In conventional flue gas heat recovery systems, the fouling by fly ashes and the related problems such as corrosion and cleaning are known to be major drawbacks. To overcome these problems, a single-riser no-distributor-fluidized-bed heat exchanger is devised and studied. Fouling and cleaning tests are performed for a uniquely designed fluidized bed-type heat exchanger to demonstrate the effect of particles on the fouling reduction and heat transfer enhancement. The tested heat exchanger model (1 m high and 54 mm internal diameter) is a gas-to-water type and composed of a main vertical tube and four auxiliary tubes through which particles circulatemore » and transfer heat. Through the present study, the fouling on the heat transfer surface could successfully be simulated by controlling air-to-fuel ratios rather than introducing particles through an external feeder, which produced soft deposit layers with 1 to 1.5 mm thickness on the inside pipe wall. Flue gas temperature at the inlet of heat exchanger was maintained at 450{sup o}C at the gas volume rate of 0.738 to 0.768 CMM (0.0123 to 0.0128 m{sup 3}/sec). From the analyses of the measured data, heat transfer performances of the heat exchanger before and after fouling and with and without particles were evaluated. Results showed that soft deposits were easily removed by introducing glass bead particles, and also heat transfer performance increased two times by the particle circulation. In addition, it was found that this type of heat exchanger had high potential to recover heat of waste gases from furnaces, boilers, and incinerators effectively and to reduce fouling related problems.« less

Kinetic theory-based numerical modeling and analysis of bi-disperse segregated mixture fluidized bed

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

Konan, N. A.; Huckaby, E. D.

We discuss a series of continuum Euler-Euler simulations of an initially mixed bi-disperse fluidized bed which segregates under certain operating conditions. The simulations use the multi-phase kinetic theory-based description of the momentum and energy exchanges between the phases by Simonin’s Group [see e.g. Gourdel, Simonin and Brunier (1999). Proceedings of 6th International Conference on Circulating Fluidized Beds, Germany, pp. 205-210]. The discussion and analysis of the results focus on the fluid-particle momentum exchange (i.e. drag). Simulations using mono- and poly-disperse fluid-particle drag correlations are analyzed for the Geldart D-type size bi-disperse gas-solid experiments performed by Goldschmidt et al. [Powder Tech.,more » pp. 135-159 (2003)]. The poly-disperse gas-particle drag correlations account for the local particle size distribution by using an effective mixture diameter when calculating the Reynolds number and then correcting the resulting force coefficient. Simulation results show very good predictions of the segregation index for bidisperse beds with the mono-disperse drag correlations contrary to the poly-disperse drag correlations for which the segregation rate is systematically under-predicted. The statistical analysis of the results shows a clear separation in the distribution of the gas-particle mean relaxation times of the small and large particles with simulations using the mono-disperse drag. In contrast, the poly-disperse drag simulations have a significant overlap and also a smaller difference in the mean particle relaxation times. This results in the small and large particles in the bed to respond to the gas similarly without enough relative time lag. The results suggest that the difference in the particle response time induce flow dynamics favorable to a force imbalance which results in the segregation.« less

Kinetic theory-based numerical modeling and analysis of bi-disperse segregated mixture fluidized bed

DOE PAGES

Konan, N. A.; Huckaby, E. D.

2017-06-21

We discuss a series of continuum Euler-Euler simulations of an initially mixed bi-disperse fluidized bed which segregates under certain operating conditions. The simulations use the multi-phase kinetic theory-based description of the momentum and energy exchanges between the phases by Simonin’s Group [see e.g. Gourdel, Simonin and Brunier (1999). Proceedings of 6th International Conference on Circulating Fluidized Beds, Germany, pp. 205-210]. The discussion and analysis of the results focus on the fluid-particle momentum exchange (i.e. drag). Simulations using mono- and poly-disperse fluid-particle drag correlations are analyzed for the Geldart D-type size bi-disperse gas-solid experiments performed by Goldschmidt et al. [Powder Tech.,more » pp. 135-159 (2003)]. The poly-disperse gas-particle drag correlations account for the local particle size distribution by using an effective mixture diameter when calculating the Reynolds number and then correcting the resulting force coefficient. Simulation results show very good predictions of the segregation index for bidisperse beds with the mono-disperse drag correlations contrary to the poly-disperse drag correlations for which the segregation rate is systematically under-predicted. The statistical analysis of the results shows a clear separation in the distribution of the gas-particle mean relaxation times of the small and large particles with simulations using the mono-disperse drag. In contrast, the poly-disperse drag simulations have a significant overlap and also a smaller difference in the mean particle relaxation times. This results in the small and large particles in the bed to respond to the gas similarly without enough relative time lag. The results suggest that the difference in the particle response time induce flow dynamics favorable to a force imbalance which results in the segregation.« less

Suppression of agglomeration in fluidized bed coating. II. Measurement of mist size in a fluidized bed chamber and effect of sodium chloride addition on mist size.

PubMed

Yuasa, H; Nakano, T; Kanaya, Y

1999-02-01

It has been reported that the degree of particle agglomeration in fluidized bed coating is greatly affected by the spray mist size of coating solution. However, the mist size has generally been measured in open air, and few reports have described the measurement of the mist size in a chamber of the fluidized bed, in which actual coating is carried out. Therefore, using hydroxypropylmethyl cellulose (HPMC) aqueous solution as a coating solution, the spray mist size of the coating solution in a chamber of the fluidized bed was measured under various coating conditions, such as the distance from the spray nozzle, fluidization air volume, inlet air temperature and addition of sodium chloride (NaCl) into the coating solution. The mist size in the fluidized bed was compared with that in open air at various distances from the spray nozzle. Further, the relationship between the spray mist size and the degree of suppression of agglomeration at various NaCl concentrations during fluidized bed coating was studied. The mist size distribution showed a logarithmic normal distribution in both cases of the fluidized bed and open air. The number-basis median diameter of spray mist (D50) in the fluidized bed was smaller compared with that in open air. D50 increased with the increasing distance from the spray nozzle in both cases. In the fluidized bed, D50 decreased with the increasing fluidization air volume and inlet air temperature. The effect of NaCl concentration on the mist size was hardly observed, but the degree of suppression of agglomeration during coating increased with the increasing NaCl concentration in the coating solution.

An investigation of the mechanisms of calcination and sulfation in coal-water mixtures

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

Christofides, N.

1990-09-21

The purpose of this investigation is to study the mechanisms of sulfur capture when burning coal-water-limestone mixtures (CWLM) in fluidized beds. Special care is taken to make comparisons with to dry coal and sorbent under comparable experimental conditions. A series of experiments were performed in an eight-inch diameter bubbling fluidized bed combustor to address this problem. 33 refs., 17 figs., 5 tabs.

Experimental study and discrete element method simulation of Geldart Group A particles in a small-scale fluidized bed

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

Li, Tingwen; Rabha, Swapna; Verma, Vikrant

Geldart Group A particles are of great importance in various chemical processes because of advantages such as ease of fluidization, large surface area, and many other unique properties. It is very challenging to model the fluidization behavior of such particles as widely reported in the literature. In this study, a pseudo-2D experimental column with a width of 5 cm, a height of 45 cm, and a depth of 0.32 cm was developed for detailed measurements of fluidized bed hydrodynamics of fine particles to facilitate the validation of computational fluid dynamic (CFD) modeling. The hydrodynamics of sieved FCC particles (Sauter meanmore » diameter of 148 µm and density of 1300 kg/m3) and NETL-32D sorbents (Sauter mean diameter of 100 µm and density of 480 kg/m3) were investigated mainly through the visualization by a high-speed camera. Numerical simulations were then conducted by using NETL’s open source code MFIX-DEM. Both qualitative and quantitative information including bed expansion, bubble characteristics, and solid movement were compared between the numerical simulations and the experimental measurement. Furthermore, the cohesive van der Waals force was incorporated in the MFIX-DEM simulations and its influences on the flow hydrodynamics were studied.« less

Experimental study and discrete element method simulation of Geldart Group A particles in a small-scale fluidized bed

DOE PAGES

Li, Tingwen; Rabha, Swapna; Verma, Vikrant; ...

2017-09-19

Geldart Group A particles are of great importance in various chemical processes because of advantages such as ease of fluidization, large surface area, and many other unique properties. It is very challenging to model the fluidization behavior of such particles as widely reported in the literature. In this study, a pseudo-2D experimental column with a width of 5 cm, a height of 45 cm, and a depth of 0.32 cm was developed for detailed measurements of fluidized bed hydrodynamics of fine particles to facilitate the validation of computational fluid dynamic (CFD) modeling. The hydrodynamics of sieved FCC particles (Sauter meanmore » diameter of 148 µm and density of 1300 kg/m3) and NETL-32D sorbents (Sauter mean diameter of 100 µm and density of 480 kg/m3) were investigated mainly through the visualization by a high-speed camera. Numerical simulations were then conducted by using NETL’s open source code MFIX-DEM. Both qualitative and quantitative information including bed expansion, bubble characteristics, and solid movement were compared between the numerical simulations and the experimental measurement. Furthermore, the cohesive van der Waals force was incorporated in the MFIX-DEM simulations and its influences on the flow hydrodynamics were studied.« less

Moving Bed Granular Bed Filter Development Program. Topical report, September 1994

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

Haas, J.C.; Prudhomme, J.W.; Wilson, K.W.

1994-09-01

Five test arrangements have been designed to support the Granular Bed Filter Development Program as defined in the Test Plan. The first arrangement is a 3.6 ft. diameter half filter, with a glass covering along the cross section to allow visual examination of the granular alumina material passing through the filter. The second test arrangement is a 3.6 ft diameter full size filter having refractory lining to simulate actual surface roughness conditions. The third test arrangement will examine filter geometry scale up by testing a 6.0 ft. diameter full size filter. The fourth Test Arrangement consists of a small 12more » inch diameter fluidizer to measure the minimum fluidization velocity of the 7 m (approx. size) alumina material to be used in the filter assemblies. The last Test Unit is used to evaluation relative abrasion characteristics of potential refractory and ceramic materials to be installed in high abrasion areas in the pneumatic transport piping.« less

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.

Combustion and NOx emissions in deep-air-staging combustion of char in a circulating fluidized bed

NASA Astrophysics Data System (ADS)

Gong, Zhiqiang; Wang, Zhentong; Wang, Lei; Du, Aixun

2017-10-01

Combustion and NOx emissions in deep-air-staging (with higher level secondary air (SA) injection) combustion of char have been investigated in a CFB test rig. A good fluidized condition and uniform temperature distribution can be achieved with injection of higher level SA. NOx emission decreases with injection of higher level SA and the reduction effect is more obvious at higher temperature. NOx emission decreases with combustion temperature increasing for char combustion.

Mineralization and defluoridation of 2,2,3,3-tetrafluoro -1-propanol (TFP) by UV oxidation in a novel three-phase fluidized bed reactor (3P-FBR).

PubMed

Shih, Yu-Jen; Tsai, Meng-Tso; Huang, Yao-Hui

2013-05-01

2,2,3,3-Tetrafluoro-1-propanol (TFP, C3H4F4O, M.W. = 132.06) is extensively used as the solvent in CD-R and DVD-R fabrication. Since it has a fluorinated alky-chain configuration and is non-biodegradable, its treatment by conventional oxidation methods is typically very inefficient. In this work, novel three-phase fluidized bed reactor (3P-FBR, 7.5 cm in diameter, 50 cm high) that combines photo oxidation (UV/H2O2, one of AOPs (Advanced Oxidation Process) and adsorption (BT5 iron oxide as adsorbent) processes is designed for mineralizing and defluorinizing TFP wastewater. The experimental results reveal that TFP can be efficiently mineralized, and the BT5 that is circulated by aeration in the 3P-FBR system can remove the released fluoride ions in the reaction period. Irradiation with 254 nm UV and a 10 mM H2O2 dose yield a TOC removal of TFP (1.39 mM, equivalent to an initial TOC of 50 ppm) of over 99.95% in 2 h, and 99% of fluoride was removed by BT5 with an adsorption capacity of 24.1 mg-F g(-1). Copyright © 2013 Elsevier Ltd. All rights reserved.

Gasification of algal biomass (Cladophora glomerata L.) with CO2/H2O/O2 in a circulating fluidized bed.

PubMed

Ebadi, Abdol Ghaffar; Hisoriev, Hikmat

2017-11-28

Gasification is one of the most important thermochemical routes to produce both synthesis gas (syngas) and chars. The quality of produced syngas wieldy depends on the operating conditions (temperature, residence time, heating rate, and gasifying agent), hydrodynamic properties of gasifier (particle size, minimum fluidization velocity, and gasifier size), and type of feedstock (coal, biomass, oil, and municipal solid wastes). In the present study, simulation of syngas production via circulating fluidized bed (CFB) gasification of algal biomass (Cladophora glomerata L.) at different gasifying agents and particle sizes was carried out, using Aspen Plus simulator. The model which has been validated by using experimental data of the technical literature was used to evaluate the influence of operating conditions on gas composition and performance parameters. The results show that biomass gasification using pure oxygen as the gasification agent has great potential to improve the caloric value of produced gas and performance indicators. It was also found that the produced gas caloric value, syngas yield, and performance parameters (CCE and CGE) increase with reaction temperature but are inversely proportional to the biomass particle size.

Thermal Analysis of Fluidized Bed and Fixed Bed Latent Heat Thermal Storage System

NASA Astrophysics Data System (ADS)

Beemkumar, N.; Karthikeyan, A.; Shiva Keshava Reddy, Kota; Rajesh, Kona; Anderson, A.

2017-05-01

Thermal energy storage technology is essential because its stores available energy at low cost. Objective of the work is to store the thermal energy in a most efficient method. This work is deal with thermal analysis of fluidized bed and fixed bed latent heat thermal storage (LHTS) system with different encapsulation materials (aluminium, brass and copper). D-Mannitol has been used as phase change material (PCM). Encapsulation material which is in orbicular shape with 4 inch diameter and 2 mm thickness orbicular shaped product is used. Therminol-66 is used as a heat transfer fluid (HTF). Arrangement of encapsulation material is done in two ways namely fluidized bed and fixed bed thermal storage system. Comparison was made between the performance of fixed bed and fluidized bed with different encapsulation material. It is observed that from the economical point of view aluminium in fluidized bed LHTS System has highest efficiency than copper and brass. The thermal energy storage system can be analyzed with fixed bed by varying mass flow rate of oil paves a way to find effective heat energy transfer.

Commercialization of the Stone and Webster/Conoco SCB technology

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

Stone, R.C.; Johnson, W.B.; Ratliff, B.D.

1982-06-01

Stone and Webster have developed a second generation recirculating fluidized bed boiler system, named Solids Circulation Boiler (SCB). The heart of the system is the recirculating fluidized bed, which is schematized, and explained. In November 1981 Conoco announced plans to construct an SCB at Lake Charles LA. Preliminary plot plan and elevation drawings are provided. The advantages of SCB are its rapid and controlled turn on and turn down capability, high carbon efficiency, simple coal and limestone feed system, high sulphur capture, compact design, and low NOx emission.

High gradient magnetic beneficiation of dry pulverized coal via upwardly directed recirculating fluidization

DOEpatents

Eissenberg, David M.; Liu, Yin-An

1980-01-01

This invention relates to an improved device and method for the high gradient magnetic beneficiation of dry pulverized coal, for the purpose of removing sulfur and ash from the coal whereby the product is a dry environmentally acceptable, low-sulfur fuel. The process involves upwardly directed recirculating air fluidization of selectively sized powdered coal in a separator having sections of increasing diameters in the direction of air flow, with magnetic field and flow rates chosen for optimum separations depending upon particulate size.

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...

An approach for modeling thermal destruction of hazardous wastes in circulating fluidized bed incinerator.

PubMed

Patil, M P; Sonolikar, R L

2008-10-01

This paper presents a detailed computational fluid dynamics (CFD) based approach for modeling thermal destruction of hazardous wastes in a circulating fluidized bed (CFB) incinerator. The model is based on Eular - Lagrangian approach in which gas phase (continuous phase) is treated in a Eularian reference frame, whereas the waste particulate (dispersed phase) is treated in a Lagrangian reference frame. The reaction chemistry hasbeen modeled through a mixture fraction/ PDF approach. The conservation equations for mass, momentum, energy, mixture fraction and other closure equations have been solved using a general purpose CFD code FLUENT4.5. Afinite volume method on a structured grid has been used for solution of governing equations. The model provides detailed information on the hydrodynamics (gas velocity, particulate trajectories), gas composition (CO, CO2, O2) and temperature inside the riser. The model also allows different operating scenarios to be examined in an efficient manner.

Application of CFB technology for large power generating units and CO{sub 2} capture

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

Ryabov, G. A., E-mail: georgy.ryabov@gmail.com; Folomeev, O. M.; Sankin, D. A.

2010-07-15

Data on the development of the circulating fluidized bed (CFB) technology for combustion of fuels in large power generating units are examined. The problems with raising the steam parameters and unit power of boilers with a circulating fluidized bed are examined. With the boiler system at the 460 MW unit at Lagisza (Poland) as an example, the feasibility of raising the efficiency of units with CFB boilers through deep recovery of the heat of the effluent gases and reducing expenditure for in-house needs is demonstrated. Comparative estimates of the capital and operating costs of 225 and 330 MW units aremore » used to determine the conditions for optimum use of CFB boilers in the engineering renovation of thermal power plants in Russia. New areas for the application of CFB technology in CO{sub 2} capture are analyzed in connection with the problem of reducing greenhouse gas emissions.« less

Design assessment of a 150 kWt CFBC Test Unit

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

Batu, A.; Selcuk, N.; Kulah, G.

2010-04-15

For clean and efficient energy generation from coal, the most suitable technology known to date is 'Fluidized Bed Combustion' technology. Applications of circulating fluidized bed (CFB) combustion technology have been steadily increasing in both capacity and number over the past decade. Designs of these units have been based on the combustion tests carried out in pilot scale facilities to determine the combustion and desulfurization characteristics of coal and limestone reserves in CFB conditions. Similarly, utilization of Turkish lignites in CFB boilers necessitates adaptation of CFB combustion technology to these resources. However, the design of these test units are not basedmore » on firing coals with high ash, volatile matter and sulfur contents like Turkish lignites. For this purpose, a 150 kWt CFB combustor test unit is designed and constructed in Chemical Engineering Department of Middle East Technical University, based on the extensive experience acquired at the existing 0.3 MWt Bubbling Atmospheric Fluidized Bed Combustor (AFBC) Test Rig. Following the commissioning tests, a combustion test is carried out for investigation of combustion characteristics of Can lignite in CFB conditions and for assessment of the design of test unit. Comparison of the design outputs with experimental results reveals that most of the predictions and assumptions have acceptable agreement with the operating conditions. In conclusion, the performance of 150 kWt CFBC Test Unit is found to be satisfactory to be utilized for the long term research studies on combustion and desulfurization characteristics of indigenous lignite reserves in circulating fluidized bed combustors. (author)« less

Equilibrium and kinetic studies of sorption of 2.4-dichlorophenol onto 2 mixtures: bamboo biochar plus calcium sulphate (BC) and hydroxyapatite plus bamboo biochar plus calcium sulphate (HBC), in a fluidized bed circulation column

DOE PAGES

Alamin, Ahmed Hassan; Kaewsichan, Lupong

2016-06-30

Sorption studies were carried out to investigate removal of 2.4-dichlorophenol (2.4-DCP) from aqueous solution in a fluidized bed by two types of adsorbent mixtures: BC (Bamboo char plus Calcium sulphate), and HBC (Hydroxyapatite plus Bamboo char plus Calcium sulphate); both manufactured in ball shape. The main material bamboo char was characterized by FTIR, DTA and SEM. The adsorption experiments were conducted in a fluidized bed circulation column. Adsorption, isotherms and kinetic studies were established under 180 min operating process time, at different initial 2.4-DCP solution concentrations ranging from 5–10 mg/L, and at different flow rates ranging from 0.25–0.75 L/min. Themore » data obtained fitted well for both the Langmuir and Freundlich isotherm models; indicating favorable condition of monolayer adsorption. The kinetics of both adsorbents complies with the pseudo second-order kinetic model. BC was proven a new effective composite and low cost adsorbent which can be applied in the field of wastewater treatment, and it can also play an important role in industry water treatment« less

Equilibrium and kinetic studies of sorption of 2.4-dichlorophenol onto 2 mixtures: bamboo biochar plus calcium sulphate (BC) and hydroxyapatite plus bamboo biochar plus calcium sulphate (HBC), in a fluidized bed circulation column

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

Alamin, Ahmed Hassan; Kaewsichan, Lupong

Sorption studies were carried out to investigate removal of 2.4-dichlorophenol (2.4-DCP) from aqueous solution in a fluidized bed by two types of adsorbent mixtures: BC (Bamboo char plus Calcium sulphate), and HBC (Hydroxyapatite plus Bamboo char plus Calcium sulphate); both manufactured in ball shape. The main material bamboo char was characterized by FTIR, DTA and SEM. The adsorption experiments were conducted in a fluidized bed circulation column. Adsorption, isotherms and kinetic studies were established under 180 min operating process time, at different initial 2.4-DCP solution concentrations ranging from 5–10 mg/L, and at different flow rates ranging from 0.25–0.75 L/min. Themore » data obtained fitted well for both the Langmuir and Freundlich isotherm models; indicating favorable condition of monolayer adsorption. The kinetics of both adsorbents complies with the pseudo second-order kinetic model. BC was proven a new effective composite and low cost adsorbent which can be applied in the field of wastewater treatment, and it can also play an important role in industry water treatment« less

Tar removal during the fluidized bed gasification of plastic waste.

PubMed

Arena, Umberto; Zaccariello, Lucio; Mastellone, Maria Laura

2009-02-01

A recycled polyethylene was fed in a pilot plant bubbling fluidized bed gasifier, having an internal diameter of 0.381 m and a maximum feeding capacity of 90 kg/h. The experimental runs were carried out under various operating conditions: the bed temperature was kept at about 850 degrees C, the equivalence ratio varied between 0.2 and 0.35, the amount of bed material was between 131 and 215 kg, the fluidizing velocity was between 0.5 and 0.7 m/s, quartz sand and olivine were used as bed material, and air and steam were used as fluidizing reactants. The results confirm that the tar removal treatments applied inside the gasifier (primary methods) can eliminate or strongly reduce the need for a further downstream cleanup of the syngas. In particular, the utilization of a natural olivine as an in situ tar reduction agent remarkably improves the quality of the product gas, in terms of both high hydrogen volumetric fraction and larger syngas yield.

Experimental investigation into the initiation and intensity of erosion in granular flows and its effect on flow dynamics with applications to pyroclastic density currents

NASA Astrophysics Data System (ADS)

Pollock, N. M.; Brand, B. D.; Roche, O.

2017-12-01

The macroscopic processes that control the behavior of pyroclastic density currents (PDCs) include the transportation and deposition of flow particles, entrainment of air, and interaction with topography. However, recent field studies demonstrate that substrate erosion by PDCs is also pervasive. Furthermore, analogue experiments suggest that erosion can increase flow runout distance up to 50%. We present the results from a series of analogue flume experiments on both non-fluidized and initially gas fluidized (i.e. high pore fluid pressure) granular flows. The experiments are designed to explore the controls on erosion initiation and intensity, and how erosion affects flow dynamics. A range of initial conditions allow us to explore how the angle of the bed (0°-20°) and diameter of substrate particles (40 to 700 μm) affect the onset of erosion. The experiments also explore how erosion, once initiated, affects the behavior of the flow in terms of velocity and runout distance. We observe that fluidized flows have increased runout distances of 50-300% relative to non-fluidized flows with the same initial conditions. Fluidized flows that travel over substrates composed of 40 μm particles consistently experience the largest increase in runout distance relative to non-fluidized flows, while flows over substrates of 80 μm particles experience the lowest increase. Erosion occurs for all experimental configurations in both non-fluidized and fluidized flows; however, the intensity of erosion varies widely, from small, millimeter-scale erosional features to decimeter sized wave-like features. Fluidized flows consistently show more intense erosion than non-fluidized flows, suggesting that the fluid-like behavior of these flows allows for efficient mixing between flow and substrate particles. These experiments demonstrate that erosion is a pervasive process for fluidized granular flows and that intense erosion is associated with increased flow runout distances. These results improve our understanding of the role of fluidization in erosion processes, what controls when PDCs become erosional, and how that erosion can alter flow behavior. To accurately model and predict hazards associated with PDCs, we must better understand erosional processes as they relate to these dangerous volcanic phenomena.

Regenerable cement sorbent for recycle fluidized-bed combustion systems. Final report

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

Yoo, H.J.; Steinberg, M.

1985-04-01

Agglomerated cement sorbent pellets (ACS) were investigated as a regenerable sorbent for the purpose of removing SO/sub 2/ in a circulating fluidized-bed combustion (CFBC) system. The systems concept is to use an intermediate size sorbent pellet so that fine flyash can be separated from the sorbent at the top end of the CFBC and the coarse gangue can be separated from the sorbent remaining in the bottom end. In this study, basic experimental data were obtained on the sulfur capture capacity and regenerability of the ACS pellets as a function of the concentration of flyash mixed with the pellets andmore » as a function of temperature. Thermogravimetric Analysis (TGA) was used for this purpose. A 40 mm bench-scale fluidized-bed unit operated with a simulated combustion gas mixture was used to determine the attrition resistance of the pellets. The results indicate that 30-100 mesh ACS pellets at 958/sup 0/C (1756/sup 0/F) maintain a 55-60% sulfation capacity mixed with coal flyash concentration up to 75% by weight. The sorbent pellets were 100% regenerable and did not lose reactivity in repeated cyclical sulfation and regeneration tests. At higher temperatures up to 1158/sup 0/C (2116/sup 0/F) reactivity towards SO/sub 2/ declines due to sintering of the flyash on the surface of the ACS pellets. Tests showed good attrition resistance with only 1% loss per cycle in cyclical operation. These initial basic results indicate that ACS pellets are potentially useful as a recoverable and regenerable high capacity SO/sub 2/ sorbent in a circulating fluidized-bed combustion system. 5 refs., 7 figs., 8 tabs.« less

Heat transfer and hydrodynamic analysis in an industrial circulating fluidized bed boiler

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

Di Maggio, T.; Piedfer, O.; Jestin, L.

In order to scale-up Circulating Fluidized Bed boilers (up to 600 MWe), Electricite de France has initiated a Research and Development program including: laboratory work on mock-up, numerical modeling and on-site tests in the 125 MWe CFB Emile Huchet plant. This paper is devoted to on-site measurements analysis in two main components of this industrial unit: the external fluidized bed heat exchangers and the backpass. This study particularly concerns hydrodynamics and heat transfer with the final target of developing a physical model of a CFB unit. The first part of this paper describes the specific instrumentation set up on externalmore » fluidized bed heat exchangers. The comparison between experimental data collected on these heat exchangers and the theoretical heat transfer models mainly used, shows a great difference about the value of the overall heat transfer coefficient. To explain this discrepancy, the particle flow pattern initially used in the thermal balance calculation is modified and a solid bypass is introduced. The analysis of the by-pass behavior, connected to the geometrical and operating parameters of each exchanger, confirms the particle flow pattern suggested. The second part of this paper shows an analysis of the specific measurements set up on the backpass to study heat transfer. The physical model of heat transfer used to assess the importance of each convection, radiation and conduction components is presented. This model allows one to assess the influence of heat exchangers design on heat transfer. Moreover, the analysis of heat transfer variations during sweeping cycles gives the amount of dust that is removed from the heat exchanger tubes. These results are used to evaluate the amount of power that can be recovered by optimizing both design and sweeping of the backpass.« less

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

Wheeler, P.A.; Patel, N.M.; Painter, A.

Energy recovery from municipal solid waste (MSW) is an important component of an integrated waste management strategy. Waste management programs which remove or recover materials for recycling are particularly suited for considering the option of energy recovery via fluidized bed combustion (FBC). The last few years have seen growing interest in the application of FBC technology to the MSW treatment/disposal problem. This paper reviews and reports on the world-wide experience in fluidized bed combustion of MSW focusing particularly on the types and scales of the systems in operation in Japan and Scandinavia. In addition the paper also reports on themore » development of an energy from waste project employing circulating fluidized bed technology that is proposed for a local municipality in the UK. Japan currently has over 100 bubbling bed units in operation firing on 100% MSW; the technology is firmly established at scales of operation up to 160,000t/y (the largest single unit operates at 6.25t/h). The bubbling bed units accept MSW which has undergone only minimal pre-processing -- the waste is shredded to a nominal 300mm size fraction before being introduced to the furnace. There are distinct (combustion control) advantages to further processing of the waste stream prior to combustion. The Scandinavian countries in particular have been the prime movers in pioneering this technology to work in combination with circulating fluidized bed systems. Currently 2 units are in operation cofiring pre-processed MSW with a range of other biofuels. A number of FBC units firing 100% MSW are currently in the planning or construction stage around the world; they seem set to secure an increased market share particularly at the smaller scale of operation (up to about 200,000t/y).« less

CFB repowering options

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

Gittinger, J.

1996-12-31

Circulating fluidized bed CFB repowering options are summarized. The following topics are discussed: why repower with CFB technology; advantages of repowering; two forms of of repowering; B and N`s internal recirculation CFB; space-saving design features; cost-saving design features; Ukrainian repowering project; and candidates for repowering.

Design and Application of Novel Horizontal Circulating Fluidized Bed Boiler

NASA Astrophysics Data System (ADS)

Lit, Q. H.; Zhang, Y. G.; Meng, A. H.

The vertical circulating fluidized bed (CFB) boiler has been found wide application in power generation and tends to be enlarged in capacity. Because CFB is one of environment friendly and high efficiency combustion technologies, the CFB boiler has also been expected to be used in the industrial area, such as textile mill, region heating, brewery, seed drying and so on. However, the necessary height of furnace is hard to be implemented for CFB with especially small capacity. Thereby, a novel horizontal circulating fluidized bed boiler has been proposed and developed. The horizontal CFB is composed of primary combustion chamber, secondary combustion chamber, burnout chamber, cyclone, loop seal, heat recovery area. The primary combustion chamber is a riser like as that in vertical CFB, and the secondary combustion chamber is a downward passage that is a natural extension of the primary riser, which can reduce the overall height of the boiler. In some extent, the burnout chamber is also the extension of primary riser. The capacity of horizontal CFB is about 4.2-24.5MWth (6-35t/h) steam output or equivalent hot water supply. The hot water boiler of 7MWth and steam boilers of 4.2MWth (6t/h) and 10.5MWth (15t/h) are all designed and working well now. The three units of hot water horizontal CFB boiler were erected in the Neimenggu Autonomous Region, Huhehaote city for region heating. The three units of steam horizontal CFB has been installed in Yunnan, Jiang Xi and Guangdong provinces, respectively. The basic principle for horizontal CFB and experiences for designing and operating are presented in this paper. Some discussions are also given to demonstrate the promising future of horizontal CFB.

Transient Characterization of Type B Particles in a Transport Riser

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

Shadle, L.J.; Monazam, E.R.; Mei, J.S.

2007-01-01

Simple and rapid dynamic tests were used to evaluate fluid dynamic behavior of granular materials in the transport regime. Particles with densities ranging from 189 to 2,500 kg/m3 and Sauter mean size from 61 to 812 μm were tested in a 0.305 m diameter, 15.5 m height circulating fluidized bed (CFB) riser. The transient tests involved the abrupt stoppage of solids flow for each granular material over a wide range gas flow rates. The riser emptying time was linearly related to the Froude number in each of three different operating regimes. The flow structure along the height of the risermore » followed a distinct pattern as tracked through incremental pressures. These results are discussed to better understand the transformations that take place when operating over various regimes. During the transients the particle size distribution was measured. The effects of pressure, particle size, and density on test performance are also presented.« less

Inversion of Crater Morphometric Data to Gain Insight on the Cratering Process

NASA Technical Reports Server (NTRS)

Herrick, Robert R.; Lyons, Suzane N.

1998-01-01

In recent years, morphometric data for Venus and several outer planet satellites have been collected, so we now have observational data of complex Craters formed in a large range of target properties. We present general inversion techniques that can utilize the morphometric data to quantitatively test various models of complex crater formation. The morphometric data we use in this paper are depth of a complex crater, the diameter at which the depth-diameter ratio changes, and onset diameters for central peaks, terraces, and peak rings. We tested the roles of impactor velocities and hydrostatic pressure vs. crustal strength, and we tested the specific models of acoustic fluidization (Melosh, 1982) and nonproportional growth (Schultz, 1988). Neither the acoustic fluidization model nor the nonproportional growth in their published formulations are able to successfully reproduce the data. No dependence on impactor velocity is evident from our inversions. Most of the morphometric data is consistent with a linear dependence on the ratio of crustal strength to hydrostatic pressure on a planet, or the factor c/pg.

Comparion of Mercury Emissions Between Circulating Fluidized Bed Boiler and Pulverized Coal Boiler

NASA Astrophysics Data System (ADS)

Wang, Y. J.; Duan, Y. F.; Zhao, C. S.

Mercury emissions between a circulating fluidized bed (CFB) utility boiler and two pulverized coal (PC) boilers equipped with electrostatic precipitators (ESP) were in situ measured and compared. The standard Ontario Hydro Method (OHM) was used to sample the flue gas before and after the ESP. Various mercury speciations such as Hg0, Hg2+ and Hgp in flue gas and total mercury in fly ashes were analyzed. The results showed that the mercury removal rate of the CFB boiler is nearly 100%; the mercury emission in stack is only 0.028 g/h. However, the mercury removal rates of the two PC boilers are 27.56% and 33.59% respectively, the mercury emissions in stack are 0.80 and 51.78 g/h respectively. It concluded that components of the ESP fly ashes especially their unburnt carbons have remarkable influence on mercury capture. Pore configurations of fine fly ash particles have non-ignored impacts on mercury emissions.

Biological treatment of fracturing waste liquid in a membrane-coupled internal circulation aerobic biological fluidized bed with the assistance of coagulation.

PubMed

Tu, Yizhou; Liu, Xing-Peng; Li, Hui-Qiang; Yang, Ping

2017-12-01

Fracturing waste liquid (FWL) is generated during shale gas extraction and contains high concentrations of suspended solid, salinity and organic compounds, which needs proper management to prevent excessive environmental disruption. Biological treatment of the FWL was attempted in this study using a membrane-coupled internal circulation aerobic biological fluidized bed (MC-ICABFB) after being treated by coagulation. The results showed that poly aluminum chloride (PAC) of 30 g/L, polyacrylamide (PAM) of 20 mg/L and pH of 7.0 were suitable choices for coagulation. The pretreated FWL mixed with synthetic wastewater at different ratios were used as the influent wastewater for the reactor. The MC-ICABFB had relatively good performance on COD and NH 4 + -N removal and the main residual organic compound in the effluent was phthalates according to the analysis of GC-MC profiles. In addition, a suitable pretreatment process for the FWL to facilitate biological treatment of the wastewater needs further research.

Integration of concentrated solar power (CSP) and circulating fluidized bed (CFB) power plants - final results of the COMBO-CFB project

NASA Astrophysics Data System (ADS)

Suojanen, Suvi; Hakkarainen, Elina; Kettunen, Ari; Kapela, Jukka; Paldanius, Juha; Tuononen, Minttu; Selek, Istvan; Kovács, Jenö; Tähtinen, Matti

2017-06-01

Hybridization of solar energy together with another energy source is an option to provide heat and power reliably on demand. Hybridization allows decreasing combustion related fuel consumption and emissions, assuring stable grid connection and cutting costs of concentrated solar power technology due to shared power production equipment. The research project "Integration of Concentrated Solar Power (CSP) and Circulating Fluidized Bed (CFB) Power Plants" (COMBO-CFB) has been carried out to investigate the technical possibilities and limitations of the concept. The main focus was on the effect of CSP integration on combustion dynamics and on the joint power cycle, and on the interactions of subsystems. The research provides new valuable experimental data and knowhow about dynamic behaviour of CFB combustion under boundary conditions of the hybrid system. Limiting factors for maximum solar share in different hybridization schemes and suggestions for enhancing the performance of the hybrid system are derived.

Evaluation of AFBC co-firing of coal and hospital wastes

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

Not Available

1991-02-01

The purpose of this program is to expand the use of coal by utilizing CFB (circulating fluidized bed) technology to provide an environmentally safe method for disposing of waste materials. Hospitals are currently experiencing a waste management crisis. In many instances, they are no longer permitted to burn pathological and infectious wastes in incinerators. Older hospital incinerators are not capable of maintaining the stable temperatures and residence times necessary in order to completely destroy toxic substances before release into the atmosphere. In addition, the number of available landfills which can safely handle these substances is decreasing each year. The purposemore » of this project is to conduct necessary research investigating whether the combustion of the hospital wastes in a coal-fired circulating fluidized bed boiler will effectively destroy dioxins and other hazardous substances before release into the atmosphere. If this is proven feasible, in light of the quantity of hospital wastes generated each year, it would create a new market for coal -- possibly 50 million tons/year.« less

Fluidized bed heat exchanger with water cooled air distributor and dust hopper

DOEpatents

Jukkola, Walfred W.; Leon, Albert M.; Van Dyk, Jr., Garritt C.; McCoy, Daniel E.; Fisher, Barry L.; Saiers, Timothy L.; Karstetter, Marlin E.

1981-11-24

A fluidized bed heat exchanger is provided in which air is passed through a bed of particulate material containing fuel. A steam-water natural circulation system is provided for heat exchange and the housing of the heat exchanger has a water-wall type construction. Vertical in-bed heat exchange tubes are provided and the air distributor is water-cooled. A water-cooled dust hopper is provided in the housing to collect particulates from the combustion gases and separate the combustion zone from a volume within said housing in which convection heat exchange tubes are provided to extract heat from the exiting combustion gases.

Correlation between loose density and compactibility of granules prepared by various granulation methods.

PubMed

Murakami, H; Yoneyama, T; Nakajima, K; Kobayashi, M

2001-03-23

The objectives of this study were to prepare the lactose granules by various granulation methods using polyethylene glycol 6000 (PEG 6000) as a binder and to evaluate the effects of granulation methods on the compressibility and compactibility of granules in tabletting. Lactose was granulated by seven granulation methods -- four wet granulations including wet massing granulation, wet high-speed mixer granulation, wet fluidized bed granulation and wet tumbling fluidized bed granulation; and three melt granulations including melt high-speed mixer granulation, melt fluidized bed granulation and melt tumbling fluidized bed granulation. The loose density, angle of repose, granule size distribution, mean diameter of granules, and the tensile strength and porosity of tablets were evaluated. The compactibilities of granules were varied by the granulation methods. However, the difference in compactibility of granules could not be explained due to the difference in compressibility, since there was no difference in Heckel plots due to granulation methods. Among their granule properties, the loose density of granules seemed to have a correlation with the tablet strength regardless of the granulation methods.

Two-dimensional numerical simulation of chimney fluidization in a granular medium using a combination of discrete element and lattice Boltzmann methods

NASA Astrophysics Data System (ADS)

Ngoma, Jeff; Philippe, Pierre; Bonelli, Stéphane; Radjaï, Farhang; Delenne, Jean-Yves

2018-05-01

We present here a numerical study dedicated to the fluidization of a submerged granular medium induced by a localized fluid injection. To this end, a two-dimensional (2D) model is used, coupling the lattice Boltzmann method (LBM) with the discrete element method (DEM) for a relevant description of fluid-grains interaction. An extensive investigation has been carried out to analyze the respective influences of the different parameters of our configuration, both geometrical (bed height, grain diameter, injection width) and physical (fluid viscosity, buoyancy). Compared to previous experimental works, the same qualitative features are recovered as regards the general phenomenology including transitory phase, stationary states, and hysteretic behavior. We also present quantitative findings about transient fluidization, for which several dimensionless quantities and scaling laws are proposed, and about the influence of the injection width, from localized to homogeneous fluidization. Finally, the impact of the present 2D geometry is discussed, by comparison to the real three-dimensional (3D) experiments, as well as the crucial role of the prevailing hydrodynamic regime within the expanding cavity, quantified through a cavity Reynolds number, that can presumably explain some substantial differences observed regarding upward expansion process of the fluidized zone when the fluid viscosity is changed.

Convection and fluidization in oscillatory granular flows: The role of acoustic streaming.

PubMed

Valverde, Jose Manuel

2015-06-01

Convection and fluidization phenomena in vibrated granular beds have attracted a strong interest from the physics community since the last decade of the past century. As early reported by Faraday, the convective flow of large inertia particles in vibrated beds exhibits enigmatic features such as frictional weakening and the unexpected influence of the interstitial gas. At sufficiently intense vibration intensities surface patterns appear bearing a stunning resemblance with the surface ripples (Faraday waves) observed for low-viscosity liquids, which suggests that the granular bed transits into a liquid-like fluidization regime despite the large inertia of the particles. In his 1831 seminal paper, Faraday described also the development of circulation air currents in the vicinity of vibrating plates. This phenomenon (acoustic streaming) is well known in acoustics and hydrodynamics and occurs whenever energy is dissipated by viscous losses at any oscillating boundary. The main argument of the present paper is that acoustic streaming might develop on the surface of the large inertia particles in the vibrated granular bed. As a consequence, the drag force on the particles subjected to an oscillatory viscous flow is notably enhanced. Thus, acoustic streaming could play an important role in enhancing convection and fluidization of vibrated granular beds, which has been overlooked in previous studies. The same mechanism might be relevant to geological events such as fluidization of landslides and soil liquefaction by earthquakes and sound waves.

Particle circulation and solids transport in large bubbling fluidized beds. Progress report

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

Homsy, G.M.

1982-04-01

We have undertaken a theoretical study of the possibility of the formation of plumes or channeling when coal particles volatilize upon introduction to a fluidized bed, Fitzgerald (1980). We have completed the analysis of the basic state of uniform flow and are currently completing a stability analysis. We have modified the continuum equations of fluidization, Homsy et al. (1980), to include the source of gas due to volatilization, which we assume to be uniformly distributed spatially. Simplifying these equations and solving leads to the prediction of a basic state analogous to the state of uniform fluidization found when no sourcemore » is present within the medium. We are currently completing a stability analysis of this basic state which will give the critical volatilization rate above which the above simple basic state is unstable. Because of the experimental evidence of Jewett and Lawless (1981), who observed regularly spaced plume-like instabilities upon drying a bed of saturated silica gel, we are considering two-dimensional periodic disturbances. The analysis is similar to that given by Homsy, et al. (1980) and Medlin et al. (1974). We hope to determine the stability limits for this system shortly.« less

Novel designs of fluidized bed combustors for low pollutant emissions

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

Lin, W.; Bleek, C.M. van den; Dam-Johansen, K.

1995-12-31

It is known that NH{sub 3}, released during the devolatilization of fuel, is an important precursor for NO formation in fluidized bed combustors. On the other hand, NH{sub 3} may be used as a reducing agent in the thermal DeNO{sub x} process to reduce NO{sub x} emission levels. In this paper, a new concept of fluidized bed combustors is proposed based on the idea of in situ reduction of NO{sub x} by self-produced NH{sub 3} from fuel without lowering the sulfur capture level. This design is intended to separate the NH{sub 3} release process under reducing conditions from the charmore » combustion process under oxidizing conditions; this self-released NH{sub 3}, together with some combustibles, is mixed with gaseous combustion products in the upper part of the combustor for a further reduction of the NO{sub x} formed during combustion. Furthermore, the combustion of the combustibles may cause the temperature to rise in this upper zone and thereby reduce the emission of N{sub 2}O. The applications of this design to bubbling and circulating fluidized bed combustors are described and the mechanisms of the main reactions involved discussed.« less

Process Analysis of Lignite Circulating Fluidized Bed Boiler Coupled with Pyrolysis Topping

NASA Astrophysics Data System (ADS)

Wang, Baoqun; Dong, Li; Wang, Yin; Matsuzawa, Y.; Xu, Guangwen

We developed a comprehensive process model in ASPEN Plus to simulate the energy and mass balances of a lignite-fueled atmospheric circulating fluidized bed (CFB) boiler integrated with coal predrying and pyrolysis topping. In this model, it is assumed that the heat from exhausted flue gas was employed for coal predrying, and the sensible heat derived from circulated bed material was used for the pyrolysis topping (endothermic process). The simulation was conducted with respectto the Yunnan Kaiyuan CFB boiler, and two representative lignite coals from Xiao Long Tan (XLT) and Xin Shao (XS) were considered. The result shows that the predrying of coal with the sensible heat of above 363 K from flue gas, the amount of coal consumed in the boiler can be reduced by 3.5% and 5.3% for XLT lignite and XS lignite, respectively. It was also found that integration of pyrolysis topping with the boiler increased the coal consumption of the boiler, and the extent of consumption-increase varies with the yields of tar and gas in the pyrolysis topping process. For agas yield of 5.2% and a tar yield of 5-6%, the consumption of XS lignite increased by about 20% comparing to that in the case without topping.

High-efficiency treatment of PTA wastewater using a biogas jet assisted anaerobic fluidized bed reactor.

PubMed

Zhang, Wei; Feng, Yangyang; Chen, Yingwen; Li, Peiwen; Zhu, Shemin; Shen, Shubao

2018-02-05

In this paper, a new type of biogas jet assisted anaerobic fluidized bed reactor loaded with a polypropylene carrier has been proposed. There was a clear improvement in the fluidized state due to the biogas assisted input when the gas/water ratio was set at 1:3 with a suitable carrier loading of 60%. When the circulating water flow is 30 L/min assisted with biogas 10 L/min, the mixing time shortens from 26 to 18 s. The performance of anaerobic biodegradation on wastewater treatment was improved largely. The chemical oxygen demand (COD) and terepthallic acid removal efficiencies were at 85.4% and 84%, respectively, at hydraulic retention time of 20 h, even when the influent COD concentration was as high as 4224 mg/L. In addition, plenty of microorganisms, attached to the carriers and assumed to be the reason behind the organic biodegradation efficiency of the proposed system, were observed using scanning electron microscopy.

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.

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.

Effect of sorbent attrition on utilization

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

Keener, T.C.; Khang, S.J.; Lee, S.K.

1992-10-01

During this period, the project has focused on two aspects of attrition; (1) mechanical attrition which is responsible for particle fracture whenever particles are moving with respect to a fixed reference frame, and (2) chemical attrition which can be responsible for particle fracture whenever particles undergo reactions. The experiments were conducted with calcium based sorbent materials. Two specific project objectives were identified and studied. The first of these was to determine the effect of temperature, particle velocity, and particle surface area on the extent of attrition in a circulating fluidized reactor. The second was to investigate if attrition could improvemore » sorbent utilization of typical calcium based sorbents of small size (<20 [mu]m). A sample of sulfated calcium hydroxide sorbent was obtained for attrition tests in a circulating fluidized bed reactor. Attempts at attriting this material in the fluidized bed were not successful, and no improvements in sorbent utilization were measured in subsequent TGA tests with the solids. However, an analysis of the other constituents in the particles revealed that a major portion of the hydroxide had been converted to calcium carbonate. This gave rise to the possibility that dolomitic hydroxide may have characteristics which may be beneficial and that improvements in utilization could be realized by means of chemical attrition. This is due to the thermal instability of magnesium carbonate at temperatures above 650[degree]F which means that magnesium oxide will be the major unreacted magnesium species in spent sorbent.« less

Effect of sorbent attrition on utilization. Final report, August 1, 1991--August 31, 1992

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

Keener, T.C.; Khang, S.J.; Lee, S.K.

1992-10-01

During this period, the project has focused on two aspects of attrition; (1) mechanical attrition which is responsible for particle fracture whenever particles are moving with respect to a fixed reference frame, and (2) chemical attrition which can be responsible for particle fracture whenever particles undergo reactions. The experiments were conducted with calcium based sorbent materials. Two specific project objectives were identified and studied. The first of these was to determine the effect of temperature, particle velocity, and particle surface area on the extent of attrition in a circulating fluidized reactor. The second was to investigate if attrition could improvemore » sorbent utilization of typical calcium based sorbents of small size (<20 {mu}m). A sample of sulfated calcium hydroxide sorbent was obtained for attrition tests in a circulating fluidized bed reactor. Attempts at attriting this material in the fluidized bed were not successful, and no improvements in sorbent utilization were measured in subsequent TGA tests with the solids. However, an analysis of the other constituents in the particles revealed that a major portion of the hydroxide had been converted to calcium carbonate. This gave rise to the possibility that dolomitic hydroxide may have characteristics which may be beneficial and that improvements in utilization could be realized by means of chemical attrition. This is due to the thermal instability of magnesium carbonate at temperatures above 650{degree}F which means that magnesium oxide will be the major unreacted magnesium species in spent sorbent.« less

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.

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.

Volume I: fluidized-bed code documentation, for the period February 28, 1983-March 18, 1983

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

Piperopoulou, H.; Finson, M.; Bloomfield, D.

1983-03-01

This documentation supersedes the previous documentation of the Fluidized-Bed Gasifier code. Volume I documents a simulation program of a Fluidized-Bed Gasifier (FBG), and Volume II documents a systems model of the FBG. The FBG simulation program is an updated version of the PSI/FLUBED code which is capable of modeling slugging beds and variable bed diameter. In its present form the code is set up to model a Westinghouse commercial scale gasifier. The fluidized bed gasifier model combines the classical bubbling bed description for the transport and mixing processes with PSI-generated models for coal chemistry. At the distributor plate, the bubblemore » composition is that of the inlet gas and the initial bubble size is set by the details of the distributor plate. Bubbles grow by coalescence as they rise. The bubble composition and temperature change with height due to transport to and from the cloud as well as homogeneous reactions within the bubble. The cloud composition also varies with height due to cloud/bubble exchange, cloud/emulsion, exchange, and heterogeneous coal char reactions. The emulsion phase is considered to be well mixed.« less

40 CFR 60.53b - Standards for municipal waste combustor operating practices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Circulating fluidized bed combustor 100 4 Pulverized coal/refuse-derived fuel mixed fuel-fired combustor 150 4 Spreader stoker coal/refuse-derived fuel mixed fuel-fired combustor 150 24 a Measured at the combustor... activated carbon injection rate during dioxin/furan or mercury testing. [60 FR 65419, Dec. 19, 1995, as...

Layered growth with bottom-spray granulation for spray deposition of drug.

PubMed

Er, Dawn Z L; Liew, Celine V; Heng, Paul W S

2009-07-30

The gap in scientific knowledge on bottom-spray fluidized bed granulation has emphasized the need for more studies in this area. This paper comparatively studied the applicability of a modified bottom-spray process and the conventional top-spray process for the spray deposition of a micronized drug during granulation. The differences in circulation pattern, mode of growth and resultant granule properties between the two processes were highlighted. The more ordered and consistent circulation pattern of particles in a bottom-spray fluidized bed was observed to give rise to layered granule growth. This resulted in better drug content uniformity among the granule batches and within a granule batch. The processes' sensitivities to wetting and feed material characteristics were also compared and found to differ markedly. Less robustness to differing process conditions was observed for the top-spray process. The resultant bottom-spray granules formed were observed to be less porous, more spherical and had good flow properties. The bottom-spray technique can thus be potentially applied for the spray deposition of drug during granulation and was observed to be a good alternative to the conventional technique for preparing granules.

Low-reactive circulating fluidized bed combustion (CFBC) fly ashes as source material for geopolymer synthesis

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

Xu Hui; Li Qin; Shen Lifeng

2010-01-15

In this contribution, low-reactive circulating fluidized bed combustion (CFBC) fly ashes (CFAs) have firstly been utilized as a source material for geopolymer synthesis. An alkali fusion process was employed to promote the dissolution of Si and Al species from the CFAs, and thus to enhance the reactivity of the ashes. A high-reactive metakaolin (MK) was also used to consume the excess alkali needed for the fusion. Reactivities of the CFAs and MK were examined by a series of dissolution tests in sodium hydroxide solutions. Geopolymer samples were prepared by alkali activation of the source materials using a sodium silicate solutionmore » as the activator. The synthesized products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffractography (XRD), as well as Fourier transform infrared spectroscopy (FTIR). The results of this study indicate that, via enhancing the reactivity by alkali fusion and balancing the Na/Al ratio by additional aluminosilicate source, low-reactive CFAs could also be recycled as an alternative source material for geopolymer production.« less

Study on the flow in the pipelines of the support system of circulating fluidized bed

NASA Astrophysics Data System (ADS)

Meng, L.; Yang, J.; Zhou, L. J.; Wang, Z. W.; Zhuang, X. H.

2013-12-01

In the support system of Circulating Fluidized Bed (Below referred to as CFB) of thermal power plant, the pipelines of primary wind are used for transporting the cold air to the boiler, which is important in controlling and combustion effect. The pipeline design will greatly affect the energy loss of the system, and accordingly affect the thermal power plant economic benefits and production environment. Three-dimensional numerical simulation is carried out for the pipeline internal flow field of a thermal power plant in this paper. Firstly three turbulence models were compared and the results showed that the SST k-ω model converged better and the energy losses predicted were closer to the experimental results. The influence of the pipeline design form on the flow characteristics are analysed, then the optimization designs of the pipeline are proposed according to the energy loss distribution of the flow field, in order to reduce energy loss and improve the efficiency of tunnel. The optimization plan turned out to be efficacious; about 36% of the pressure loss is reduced.

Evaluation of AFBC co-firing of coal and hospital wastes. Technical report, January 1989--August 1990

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

Not Available

1991-02-01

The purpose of this program is to expand the use of coal by utilizing CFB (circulating fluidized bed) technology to provide an environmentally safe method for disposing of waste materials. Hospitals are currently experiencing a waste management crisis. In many instances, they are no longer permitted to burn pathological and infectious wastes in incinerators. Older hospital incinerators are not capable of maintaining the stable temperatures and residence times necessary in order to completely destroy toxic substances before release into the atmosphere. In addition, the number of available landfills which can safely handle these substances is decreasing each year. The purposemore » of this project is to conduct necessary research investigating whether the combustion of the hospital wastes in a coal-fired circulating fluidized bed boiler will effectively destroy dioxins and other hazardous substances before release into the atmosphere. If this is proven feasible, in light of the quantity of hospital wastes generated each year, it would create a new market for coal -- possibly 50 million tons/year.« less

Release of sulfur and chlorine during cofiring RDF and coal in an internally circulating fluidized bed

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

Xiaolin Wei; Yang Wang; Dianfu Liu

2009-03-15

An internally circulating fluidized bed (ICFB) was applied to investigate the behavior of chlorine and sulfur during cofiring RDF and coal. The pollutant emissions in the flue gas were measured by Fourier transform infrared (FTIR) spectrometry (Gasmet DX-3000). In the tests, the concentrations of the species CO, CO{sub 2}, HCl, and SO{sub 2} were measured online. Results indicated when cofiring RDF and char, due to the higher content of chlorine in RDF, the formation of HCl significantly increases. The concentration of SO{sub 2} is relatively low because alkaline metal in the fuel ash can absorb SO{sub 2}. The concentration ofmore » CO emission during firing pure RDF is relatively higher and fluctuates sharply. With the CaO addition, the sulfur absorption by calcium quickly increases, and the desulfurization ratio is bigger than the dechlorination ratio. The chemical equilibrium method is applied to predict the behavior of chlorine. Results show that gaseous HCl emission increases with increasing RDF fraction, and gaseous KCl and NaCl formation might occur. 35 refs., 18 figs., 2 tabs.« less

An innovative example of herb residues recycling by gasification in a fluidized bed.

PubMed

Guo, Feiqiang; Dong, Yuping; Dong, Lei; Jing, Yuanzhuo

2013-04-01

A utilization way of herb residues is designed to convert herb residues to gas fuel in industrial-scale by a circulating fluidized bed gasifier in this paper. The product gas is used in the production of Chinese medicine, and the heat of the flue gas from the boiler can be used in herb residues drying to realize the energy recycling and no herb residues discharge. The gasification characteristics of herb residues in the circulating fluidized bed of 300 kg/h were investigated for about 200 h. The results indicated that the gas composition and tar yield were affected by biomass flow rate, equivalence ratio (ER), moisture content and char circulating. The lower heating value of product gas was 4-5 MJ/m(3) using herb residues as feedstock. When mean biomass flow rate was at 5.5 kg m(-2)s(-1) and ER at 0.35, the product gas reached a good condition with lower heating value of 4.89 MJ/m(3) and cold gas efficiency of 62.36%. When the moisture content changed from 12.5% to 18.7%, the concentrations of H2, CO and CO2 changed from 4.66% to 6.92%, 11.23% to 10.15%, and 16.55% to 17.82% respectively, and the tar content in gas decreased from 15.1g/m(3) to 14.4 g/m(3) when the moisture content increased from 12.5% to 15.4%. There are metal oxides in the ash of herb residues, especially CaO, MgO, K2O, Al2O3, and Fe2O3 which have obvious function on tar catalytic decomposition. The ash that attaches to the char particles can decrease the tar yield and improve the quality of gas after returning to the gasifier. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

Modeling of chemical reactions in afterburning for the reduction of N{sub 2}O

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

Gustavsson, L.; Glarborg, P.; Leckner, B.

1996-08-01

Afterburning involves burning a secondary fuel in the flue gases from a fluidized bed combustor to raise the temperature, and thereby decrease the emission of N{sub 2}O. Tests in a 12-MW circulating fluidized bed boiler used the cyclone as an afterburning combustor. The results from these tests are analyzed by chemical kinetic calculations with homogeneous hydrocarbon and nitrogen chemistry. Furthermore, a study is made of the influence on the calculation of particles in the flue gases. The deviation between calculated and measured data is small at high temperatures, but increases at the lower temperatures investigated. The influence of particles ismore » predicted to be small under conditions prevailing in the cyclone.« less

CFD Modelling of Particle Mixtures in a 2D CFB

NASA Astrophysics Data System (ADS)

Seppälä, M.; Kallio, S.

The capability of Fluent 6.2.16 to simulate particle mixtures in a laboratory scale 2D circulating fluidized bed (CFB) unit has been tested. In the simulations, the solids were described as one or two particle phases. The loading ratio of small to large particles, particle diameters and the gas inflow velocity were varied. The 40 cm wide and 3 m high 2D CFB was modeled using a grid with 31080 cells. The outflow of particles at the top of the CFB was monitored and emanated particles were fed back to the riser through a return duct. The paper presents the segregation patterns of the particle phases obtained from the simulations. When the fraction of large particles was 50% or larger, large particles segregated, as expected, to the wall regions and to the bottom part of the riser. However, when the fraction of large particles was 10%, an excess of large particles was found in the upper half of the riser. The explanation for this unexpected phenomenon was found in the distribution of the large particles between the slow clusters and the faster moving lean suspension.

Self-assembly modified-mushroom nanocomposite for rapid removal of hexavalent chromium from aqueous solution with bubbling fluidized bed.

PubMed

Xu, Fei; Liu, Xu; Chen, Yijiao; Zhang, Ke; Xu, Heng

2016-05-18

A self-assembled modified Pleurotus Cornucopiae material (SMPM) combined with improved Intermittent Bubbling Fluidized Bed (IBFB) was investigated to remove the hexavalent chromium ions in aqueous solution. After the modification, the powder-like raw material gradually self-assembled together to SMPM, which had crinkly porous structure, improved the Cr-accommodation ability in a sound manner. Optimized by Taguchi method, Cr(VI) removal efficiency was up to 75.91% and 48.01% for 100 mg/L and 500 mg/L initial concentration of Cr(VI), respectively. Results indicated that the metal removal was dependent on dosage of adsorbent, particle diameter and treatment time. The experimental data obtained from the biosorption process was successfully correlated with Freundlich isotherm model. Thermodynamic study indicated the endothermic nature of the process. The results confirmed that self-assembly modified Pleurotus Cornucopiae material could be applied for the removal of heavy metal from wastewater in continuous fluidized bed process.

Self-assembly modified-mushroom nanocomposite for rapid removal of hexavalent chromium from aqueous solution with bubbling fluidized bed

PubMed Central

Xu, Fei; Liu, Xu; Chen, Yijiao; Zhang, Ke; Xu, Heng

2016-01-01

A self-assembled modified Pleurotus Cornucopiae material (SMPM) combined with improved Intermittent Bubbling Fluidized Bed (IBFB) was investigated to remove the hexavalent chromium ions in aqueous solution. After the modification, the powder-like raw material gradually self-assembled together to SMPM, which had crinkly porous structure, improved the Cr-accommodation ability in a sound manner. Optimized by Taguchi method, Cr(VI) removal efficiency was up to 75.91% and 48.01% for 100 mg/L and 500 mg/L initial concentration of Cr(VI), respectively. Results indicated that the metal removal was dependent on dosage of adsorbent, particle diameter and treatment time. The experimental data obtained from the biosorption process was successfully correlated with Freundlich isotherm model. Thermodynamic study indicated the endothermic nature of the process. The results confirmed that self-assembly modified Pleurotus Cornucopiae material could be applied for the removal of heavy metal from wastewater in continuous fluidized bed process. PMID:27188258

Self-assembly modified-mushroom nanocomposite for rapid removal of hexavalent chromium from aqueous solution with bubbling fluidized bed

NASA Astrophysics Data System (ADS)

Xu, Fei; Liu, Xu; Chen, Yijiao; Zhang, Ke; Xu, Heng

2016-05-01

A self-assembled modified Pleurotus Cornucopiae material (SMPM) combined with improved Intermittent Bubbling Fluidized Bed (IBFB) was investigated to remove the hexavalent chromium ions in aqueous solution. After the modification, the powder-like raw material gradually self-assembled together to SMPM, which had crinkly porous structure, improved the Cr-accommodation ability in a sound manner. Optimized by Taguchi method, Cr(VI) removal efficiency was up to 75.91% and 48.01% for 100 mg/L and 500 mg/L initial concentration of Cr(VI), respectively. Results indicated that the metal removal was dependent on dosage of adsorbent, particle diameter and treatment time. The experimental data obtained from the biosorption process was successfully correlated with Freundlich isotherm model. Thermodynamic study indicated the endothermic nature of the process. The results confirmed that self-assembly modified Pleurotus Cornucopiae material could be applied for the removal of heavy metal from wastewater in continuous fluidized bed process.

Particulate Formation from a Copper Oxide-Based Oxygen Carrier in Chemical Looping Combustion for CO2 Capture

EPA Science Inventory

Attrition behavior and particle loss of a copper oxide-based oxygen carrier from a methane chemical looping combustion (CLC) process was investigated in a fluidized bed reactor. The aerodynamic diameters of most elutriated particulates, after passing through a horizontal settling...

76 FR 20634 - Withdrawal of Notice of Intent To Prepare a Supplemental Environmental Impact Statement for a...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-13

... combustion by-products (CCB); two (2) landfills for the on-site disposal of CCB; an emergency drought water... Bed Electric Generating Unit by East Kentucky Power Cooperative, Inc., in Clark County, KY AGENCY: U.S... circulating fluidized bed electric generating unit by East Kentucky Power Cooperative, Inc. (EKPC), in Clark...

Carbon attrition during the circulating fluidized bed combustion of a packaging-derived fuel

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

Mastellone, M.L.; Arena, U.

1999-05-01

Cylindrical pellets of a market-available packaging-derived fuel, obtained from a mono-material collection of polyethylene terephthalate (PET) bottles, were batchwise fed to a laboratory scale circulating fluidized bed (CFB) combustor. The apparatus, whose riser was 41 mm ID and 4 m high, was operated under both inert and oxidizing conditions to establish the relative importance of purely mechanical attrition and combustion-assisted attrition in generating carbon fines. Silica sand particles of two size distributions were used as inert materials. For each run, carbon load and carbon particle size distribution in the riser and rates of attrited carbon fines escaping the combustor weremore » determined as a function of time. A parallel investigation was carried out with a bubbling fluidized bed (BFB) combustor to point out peculiarities of attrition in CFB combustors. After devolatilization, PET pellets generated fragile aggregates of char and sand, which easily crumbled, leading to single particles, partially covered by a carbon-rich layer. The injected fixed carbon was therefore present in the bed in three phases: an A-phase, made of aggregates of sand and char, an S-phase, made of individual carbon-covered sand particles and an F-phase, made of carbon fines, abraded by the surfaces of the A- and S-phases. The effects of the size of inert material on the different forms under which fixed carbon was present in the bed and on the rate of escape of attrited carbon fines from the combustor were investigated. Features of carbon attrition in CFB and BFB combustors are discussed.« less

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

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.

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.

Multi-stage circulating fluidized bed syngas cooling

DOEpatents

Liu, Guohai; Vimalchand, Pannalal; Guan, Xiaofeng; Peng, WanWang

2016-10-11

A method and apparatus for cooling hot gas streams in the temperature range 800.degree. C. to 1600.degree. C. using multi-stage circulating fluid bed (CFB) coolers is disclosed. The invention relates to cooling the hot syngas from coal gasifiers in which the hot syngas entrains substances that foul, erode and corrode heat transfer surfaces upon contact in conventional coolers. The hot syngas is cooled by extracting and indirectly transferring heat to heat transfer surfaces with circulating inert solid particles in CFB syngas coolers. The CFB syngas coolers are staged to facilitate generation of steam at multiple conditions and hot boiler feed water that are necessary for power generation in an IGCC process. The multi-stage syngas cooler can include internally circulating fluid bed coolers, externally circulating fluid bed coolers and hybrid coolers that incorporate features of both internally and externally circulating fluid bed coolers. Higher process efficiencies can be realized as the invention can handle hot syngas from various types of gasifiers without the need for a less efficient precooling step.

Simulation of fluidized bed combustors. I - Combustion efficiency and temperature profile. [for coal-fired gas turbines

NASA Technical Reports Server (NTRS)

Horio, M.; Wen, C. Y.

1976-01-01

A chemical engineering analysis is made of fluidized-bed combustor (FBC) performance, with FBC models developed to aid estimation of combustion efficiency and axial temperature profiles. The FBC is intended for combustion of pulverized coal and a pressurized FBC version is intended for firing gas turbines by burning coal. Transport phenomena are analyzed at length: circulation, mixing models, drifting, bubble wake lift, heat transfer, division of the FB reactor into idealized mixing cells. Some disadvantages of a coal FBC are pointed out: erosion of immersed heat-transfer tubing, complex feed systems, carryover of unburned coal particles, high particulate emission in off-streams. The low-temperature bed (800-950 C) contains limestone, and flue-gas-entrained SO2 and NOx can be kept within acceptable limits.

Preparation and characterization of bio-oils from internally circulating fluidized-bed pyrolyses of municipal, livestock, and wood waste.

PubMed

Cao, Jing-Pei; Xiao, Xian-Bin; Zhang, Shou-Yu; Zhao, Xiao-Yan; Sato, Kazuyoshi; Ogawa, Yukiko; Wei, Xian-Yong; Takarada, Takayuki

2011-01-01

Fast pyrolyses of sewage sludge (SS), pig compost (PC), and wood chip (WC) were investigated in an internally circulating fluidized-bed to evaluate bio-oil production. The pyrolyses were performed at 500 °C and the bio-oil yields from SS, PC, and WC were 45.2%, 44.4%, and 39.7% (dried and ash-free basis), respectively. The bio-oils were analyzed with an elemental analyzer, Karl-Fischer moisture titrator, bomb calorimeter, Fourier transformation infrared spectrometer, gel permeation chromatograph, and gas chromatography/mass spectrometry. The results show that the bio-oil from SS is rich in aliphatic and organonitrogen species, while the bio-oil from PC exhibits higher caloric value due to its higher carbon content and lower oxygen content in comparison with that from SS. The bio-oils from SS and PC have similar chemical composition of organonitrogen species. Most of the compounds detected in the bio-oil from WC are organooxygen species. Because of its high oxygen content, low H/C ratio, and caloric value, the bio-oil from WC is unfeasible for use as fuel feedstock, but possible for use as chemical feedstock. Copyright © 2010 Elsevier Ltd. All rights reserved.

Advanced treatment of biologically pretreated coal chemical industry wastewater using the catalytic ozonation process combined with a gas-liquid-solid internal circulating fluidized bed reactor.

PubMed

Li, Zhipeng; Liu, Feng; You, Hong; Ding, Yi; Yao, Jie; Jin, Chao

2018-04-01

This paper investigated the performance of the combined system of catalytic ozonation and the gas-liquid-solid internal circulating fluidized bed reactor for the advanced treatment of biologically pretreated coal chemical industry wastewater (CCIW). The results indicated that with ozonation alone for 60min, the removal efficiency of chemical oxygen demand (COD) could reach 34%. The introduction of activated carbon, pumice, γ-Al 2 O 3 carriers improved the removal performance of COD, and the removal efficiency was increased by 8.6%, 4.2%, 2%, respectively. Supported with Mn, the catalytic performance of activated carbon and γ-Al 2 O 3 were improved significantly with COD removal efficiencies of 46.5% and 41.3%, respectively; however, the promotion effect of pumice supported with Mn was insignificant. Activated carbon supported with Mn had the best catalytic performance. The catalytic ozonation combined system of MnO X /activated carbon could keep ozone concentration at a lower level in the liquid phase, and promote the transfer of ozone from the gas phase to the liquid phase to improve ozonation efficiency.

Gasification of high ash, high ash fusion temperature bituminous coals

DOEpatents

Liu, Guohai; Vimalchand, Pannalal; Peng, WanWang

2015-11-13

This invention relates to gasification of high ash bituminous coals that have high ash fusion temperatures. The ash content can be in 15 to 45 weight percent range and ash fusion temperatures can be in 1150.degree. C. to 1500.degree. C. range as well as in excess of 1500.degree. C. In a preferred embodiment, such coals are dealt with a two stage gasification process--a relatively low temperature primary gasification step in a circulating fluidized bed transport gasifier followed by a high temperature partial oxidation step of residual char carbon and small quantities of tar. The system to process such coals further includes an internally circulating fluidized bed to effectively cool the high temperature syngas with the aid of an inert media and without the syngas contacting the heat transfer surfaces. A cyclone downstream of the syngas cooler, operating at relatively low temperatures, effectively reduces loading to a dust filtration unit. Nearly dust- and tar-free syngas for chemicals production or power generation and with over 90%, and preferably over about 98%, overall carbon conversion can be achieved with the preferred process, apparatus and methods outlined in this invention.

Statistics of velocity fluctuations of Geldart A particles in a circulating fluidized bed riser

DOE PAGES

Vaidheeswaran, Avinash; Shaffer, Franklin; Gopalan, Balaji

2017-11-21

Here, the statistics of fluctuating velocity components are studied in the riser of a closed-loop circulating fluidized bed with fluid catalytic cracking catalyst particles. Our analysis shows distinct similarities as well as deviations compared to existing theories and bench-scale experiments. The study confirms anisotropic and non-Maxwellian distribution of fluctuating velocity components. The velocity distribution functions (VDFs) corresponding to transverse fluctuations exhibit symmetry, and follow a stretched-exponential behavior up to three standard deviations. The form of the transverse VDF is largely determined by interparticle interactions. The tails become more overpopulated with an increase in particle loading. The observed deviations from themore » Gaussian distribution are represented using the leading order term in the Sonine expansion, which is commonly used to approximate the VDFs in kinetic theory for granular flows. The vertical fluctuating VDFs are asymmetric and the skewness shifts as the wall is approached. In comparison to transverse fluctuations, the vertical VDF is determined by the local hydrodynamics. This is an observation of particle velocity fluctuations in a large-scale system and their quantitative comparison with the Maxwell-Boltzmann statistics.« less

Cost and performance of coal-based energy in Brazil

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

Temchin, J.; DeLallo, M.R.

1998-07-01

As part of the US Department of Energy's (DOE) efforts to establish the strategic benefits of Clean Coal Technologies (CCT), there is a need to evaluate the specific market potential where coal is a viable option. One such market is Brazil, where significant growth in economic development requires innovative and reliable technologies to support the use of domestic coal. While coal is Brazil's most abundant and economic fossil energy resource, it is presently under utilized in the production of electrical power. This report presents conceptual design for pulverized coal (PC) and circulating fluidized-bed combustion (CFBC) options with resulting capital, operatingmore » and financial parameters based on Brazil application conditions. Recent PC and CFBC plant capital costs have dropped with competition in the generation market and have established a competitive position in power generation. Key issues addressed in this study include: Application of market based design approach for FBC and PC, which is competitive within the current domestic, and international power generation markets. Design, fabrication, purchase, and construction methods which reduce capital investment while maintaining equipment quality and plant availability. Impact on coast and performance from application of Brazilian coals, foreign trade and tax policies, construction logistics, and labor requirements. Nominal production values of 200 MWe and 400 MWe were selected for the CFBC power plant and 400 MWe for the PC. The 400 MWe size was chosen to be consistent with the two largest Brazilian PC units. Fluidized bed technology, with limited experience in single units over 200 MW, would consist of two 200 MWe circulating fluidized bed boilers supplying steam to one steam turbine for the 400 MWe capacity. A 200 MWe capacity unit was also developed for CFBC option to support opportunities in re-powering and where specific site or other infrastructure constraints limit production.« less

Extension of a coarse grained particle method to simulate heat transfer in fluidized beds

DOE PAGES

Lu, Liqiang; Morris, Aaron; Li, Tingwen; ...

2017-04-18

The heat transfer in a gas-solids fluidized bed is simulated with computational fluid dynamic-discrete element method (CFD-DEM) and coarse grained particle method (CGPM). In CGPM fewer numerical particles and their collisions are tracked by lumping several real particles into a computational parcel. Here, the assumption is that the real particles inside a coarse grained particle (CGP) are made from same species and share identical physical properties including density, diameter and temperature. The parcel-fluid convection term in CGPM is calculated using the same method as in DEM. For all other heat transfer mechanisms, we derive in this study mathematical expressions thatmore » relate the new heat transfer terms for CGPM to those traditionally derived in DEM. This newly derived CGPM model is verified and validated by comparing the results with CFD-DEM simulation results and experiment data. The numerical results compare well with experimental data for both hydrodynamics and temperature profiles. Finally, the proposed CGPM model can be used for fast and accurate simulations of heat transfer in large scale gas-solids fluidized beds.« less

Extension of a coarse grained particle method to simulate heat transfer in fluidized beds

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

Lu, Liqiang; Morris, Aaron; Li, Tingwen

The heat transfer in a gas-solids fluidized bed is simulated with computational fluid dynamic-discrete element method (CFD-DEM) and coarse grained particle method (CGPM). In CGPM fewer numerical particles and their collisions are tracked by lumping several real particles into a computational parcel. Here, the assumption is that the real particles inside a coarse grained particle (CGP) are made from same species and share identical physical properties including density, diameter and temperature. The parcel-fluid convection term in CGPM is calculated using the same method as in DEM. For all other heat transfer mechanisms, we derive in this study mathematical expressions thatmore » relate the new heat transfer terms for CGPM to those traditionally derived in DEM. This newly derived CGPM model is verified and validated by comparing the results with CFD-DEM simulation results and experiment data. The numerical results compare well with experimental data for both hydrodynamics and temperature profiles. Finally, the proposed CGPM model can be used for fast and accurate simulations of heat transfer in large scale gas-solids fluidized beds.« less

Research on coal-water fuel combustion in a circulating fluidized bed / Badanie spalania zawiesinowych paliw węglowo-wodnych w cyrkulacyjnej warstwie fluidalnej

NASA Astrophysics Data System (ADS)

Kijo-Kleczkowska, Agnieszka

2012-10-01

In the paper the problem of heavily-watered fuel combustion has been undertaken as the requirements of qualitative coals combusted in power stations have been growing. Coal mines that want to fulfill expectations of power engineers have been forced to extend and modernize the coal enrichment plants. This causes growing quantity of waste materials that arise during the process of wet coal enrichment containing smaller and smaller under-grains. In this situation the idea of combustion of transported waste materials, for example in a hydraulic way to the nearby power stations appears attractive because of a possible elimination of the necessary deep dehydration and drying as well as because of elimination of the finest coal fraction loss arising during discharging of silted water from coal wet cleaning plants. The paper presents experimental research results, analyzing the process of combustion of coal-water suspension depending on the process conditions. Combustion of coal-water suspensions in fluidized beds meets very well the difficult conditions, which should be obtained to use the examined fuel efficiently and ecologically. The suitable construction of the research stand enables recognition of the mechanism of coal-water suspension contact with the inert material, that affects the fluidized bed. The form of this contact determines conditions of heat and mass exchange, which influence the course of a combustion process. The specificity of coal-water fuel combustion in a fluidized bed changes mechanism and kinetics of the process.

Morphology of Lonar Crater, India: Comparisons and implications

USGS Publications Warehouse

Fudali, R.F.; Milton, D.J.; Fredriksson, K.; Dube, A.

1980-01-01

Lonar Crater is a young meteorite impact crater emplaced in Deccan basalt. Data from 5 drillholes, a gravity network, and field mapping are used to reconstruct its original dimensions, delineate the nature of the pre-impact target rocks, and interpret the emplacement mode of the ejecta. Our estimates of the pre-erosion dimensions are: average diameter of 1710 m; average rim height of 40 m (30-35 m of rim rock uplift, 5-10 m of ejected debris); depth of 230-245 m (from rim crest to crater floor). The crater's circularity index is 0.9 and is unlikely to have been lower in the past. There are minor irregularities in the original crater floor (present sediment-breccia boundary) possibly due to incipient rebound effects. A continuous ejecta blanket extends an average of 1410 m beyond the pre-erosion rim crest. In general, 'fresh' terrestrial craters, less than 10 km in diameter, have smaller depth/diameter and larger rim height/diameter ratios than their lunar counterparts. Both ratios are intermediate for Mercurian craters, suggesting that crater shape is gravity dependent, all else being equal. Lonar demonstrates that all else is not always equal. Its depth/diameter ratio is normal but, because of less rim rock uplift, its rim height/diameter ratio is much smaller than both 'fresh' terrestrial and lunar impact craters. The target rock column at Lonar consists of one or more layers of weathered, soft basalt capped by fresh, dense flows. Plastic deformation and/or compaction of this lower, incompetent material probably absorbed much of the energy normally available in the cratering process for rim rock uplift. A variety of features within the ejecta blanket and the immediately underlying substrate, plus the broad extent of the blanket boundaries, suggest that a fluidized debris surge was the dominant mechanism of ejecta transportation and deposition at Lonar. In these aspects, Lonar should be a good analog for the 'fluidized craters' of Mars. ?? 1980 D. Reidel Publishing Co.

Martian subsurface properties and crater formation processes inferred from fresh impact crater geometries

NASA Astrophysics Data System (ADS)

Stewart, Sarah T.; Valiant, Gregory J.

2006-10-01

The geometry of simple impact craters reflects the properties of the target materials, and the diverse range of fluidized morphologies observed in Martian ejecta blankets are controlled by the near-surface composition and the climate at the time of impact. Using the Mars Orbiter Laser Altimeter (MOLA) data set, quantitative information about the strength of the upper crust and the dynamics of Martian ejecta blankets may be derived from crater geometry measurements. Here, we present the results from geometrical measurements of fresh craters 3-50 km in rim diameter in selected highland (Lunae and Solis Plana) and lowland (Acidalia, Isidis, and Utopia Planitiae) terrains. We find large, resolved differences between the geometrical properties of the freshest highland and lowland craters. Simple lowland craters are 1.5-2.0 times deeper (≥5σo difference) with >50% larger cavities (≥2σo) compared to highland craters of the same diameter. Rim heights and the volume of material above the preimpact surface are slightly greater in the lowlands over most of the size range studied. The different shapes of simple highland and lowland craters indicate that the upper ˜6.5 km of the lowland study regions are significantly stronger than the upper crust of the highland plateaus. Lowland craters collapse to final volumes of 45-70% of their transient cavity volumes, while highland craters preserve only 25-50%. The effective yield strength of the upper crust in the lowland regions falls in the range of competent rock, approximately 9-12 MPa, and the highland plateaus may be weaker by a factor of 2 or more, consistent with heavily fractured Noachian layered deposits. The measured volumes of continuous ejecta blankets and uplifted surface materials exceed the predictions from standard crater scaling relationships and Maxwell's Z model of crater excavation by a factor of 3. The excess volume of fluidized ejecta blankets on Mars cannot be explained by concentration of ejecta through nonballistic emplacement processes and/or bulking. The observations require a modification of the scaling laws and are well fit using a scaling factor of ˜1.4 between the transient crater surface diameter to the final crater rim diameter and excavation flow originating from one projectile diameter depth with Z = 2.7. The refined excavation model provides the first observationally constrained set of initial parameters for study of the formation of fluidized ejecta blankets on Mars.

Coal-Gen attendees hear there's no magic bullet

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

NONE

2007-09-15

Those attending COAL-GEN 2007 in August heard that there is no magic bullet for meeting the energy and infrastructure needs facing the USA. The article reports on the conference which addressed topics including development of supercritical circulating fluidized bed coal unit; IGCC projects, the importance of including carbon capture and sequestration, and the need to attract and train personnel to work in the power industry. 3 photos.

JPRS Report, Science & Technology. China: Energy.

DTIC Science & Technology

1992-12-24

desulfurization tech- nology at the present time. The wet method technology accounts for 86 percent of all of the world’s flue gas desulfurization facilities...Limestone-gypsum wet method desulfurization tech- nology Huaneng’s Luohuang Power Plant has already imported two sets of 360MW generator boiler flue gas ...Circulating Fluidized-Bed Technology Development [LinZhaokui, Wang Dun’en, et al; DONGLIGONGCHENG, 15 Oct 92] 27 Selection of Flue

Numerical Simulation on Hydrodynamics and Combustion in a Circulating Fluidized Bed under O2/CO2 and Air Atmospheres

NASA Astrophysics Data System (ADS)

Zhou, W.; Zhao, C. S.; Duan, L. B.; Qu, C. R.; Lu, J. Y.; Chen, X. P.

Oxy-fuel circulating fluidized bed (CFB) combustion technology is in the stage of initial development for carbon capture and storage (CCS). Numerical simulation is helpful to better understanding the combustion process and will be significant for CFB scale-up. In this paper, a computational fluid dynamics (CFD) model was employed to simulate the hydrodynamics of gas-solid flow in a CFB riser based on the Eulerian-Granular multiphase model. The cold model predicted the main features of the complex gas-solid flow, including the cluster formation of the solid phase along the walls, the flow structure of up-flow in the core and downward flow in the annular region. Furthermore, coal devolatilization, char combustion and heat transfer were considered by coupling semi-empirical sub-models with CFD model to establish a comprehensive model. The gas compositions and temperature profiles were predicted and the outflow gas fractions are validated with the experimental data in air combustion. With the experimentally validated model being applied, the concentration and temperature distributions in O2/CO2 combustion were predicted. The model is useful for the further development of a comprehensive model including more sub-models, such as pollutant emissions, and better understanding the combustion process in furnace.

CFD Modelling Applied to the Co-Combustion of Paper Sludge and Coal in a 130 t/h CFB Boiler

NASA Astrophysics Data System (ADS)

Yu, Z. S.; Ma, X. Q.; Lai, Z. Y.; Xiao, H. M.

Three-dimensional mathematical model has been developed as a tool for co-combustion of paper sludge and coal in a 130 tJh Circulating Fluidized Bed (CFB) boiler. Mathematical methods had been used based on a commercial software FLUENT for combustion. The predicted results of CFB furnace show that the co-combustion of paper sludge/coal is initially intensively at the bottom of bed; the temperature reaches its maximum in the dense-phase zone, around l400K. It indicates that paper sludge spout into furnace from the recycle inlet can increase the furnace maximum temperature (l396.3K), area-weighted average temperature (l109.6K) and the furnace gas outlet area-weighted average temperature(996.8K).The mathematical modeling also predicts that 15 mass% paper sludge co-combustion is the highest temperature at the flue gas outlet, it is 1000.8K. Moreover, it is proved that mathematical models can serve as a tool for detailed analysis of co-combustion of paper sludge and coal processes in a circulating fluidized bed furnace when in view of its convenience. The results gained from numerical simulation show that paper sludge enter into furnace from the recycle inlet excelled than mixing with coal and at the underside of phase interface.

Development of methane and nitrous oxide emission factors for the biomass fired circulating fluidized bed combustion power plant.

PubMed

Cho, Chang-Sang; Sa, Jae-Hwan; Lim, Ki-Kyo; Youk, Tae-Mi; Kim, Seung-Jin; Lee, Seul-Ki; Jeon, Eui-Chan

2012-01-01

This study makes use of this distinction to analyze the exhaust gas concentration and fuel of the circulating fluidized bed (CFB) boiler that mainly uses wood biomass, and to develop the emission factors of Methane (CH(4)), Nitrous oxide (N(2)O). The fuels used as energy sources in the subject working sites are Wood Chip Fuel (WCF), RDF and Refused Plastic Fuel (RPF) of which heating values are 11.9 TJ/Gg, 17.1 TJ/Gg, and 31.2 TJ/Gg, respectively. The average concentrations of CH(4) and N(2)O were measured to be 2.78 ppm and 7.68 ppm, respectively. The analyzed values and data collected from the field survey were used to calculate the emission factor of CH(4) and N(2)O exhausted from the CFB boiler. As a result, the emission factors of CH(4) and N(2)O are 1.4 kg/TJ (0.9-1.9 kg/TJ) and 4.0 kg/TJ (2.9-5.3 kg/TJ) within a 95% confidence interval. Biomass combined with the combustion technology for the CFB boiler proved to be more effective in reducing the N(2)O emission, compared to the emission factor of the CFB boiler using fossil fuel.

Investigation of gas-solids flow in a circulating fluidized bed using 3D electrical capacitance tomography

NASA Astrophysics Data System (ADS)

Mao, Mingxu; Ye, Jiamin; Wang, Haigang; Yang, Wuqiang

2016-09-01

The hydrodynamics of gas-solids flow in the bottom of a circulating fluidized bed (CFB) are complicated. Three-dimensional (3D) electrical capacitance tomography (ECT) has been used to investigate the hydrodynamics in risers of different shapes. Four different ECT sensors with 12 electrodes each are designed according to the dimension of risers, including two circular ECT sensors, a square ECT sensor and a rectangular ECT sensor. The electrodes are evenly arranged in three planes to obtain capacitance in different heights and to reconstruct the 3D images by linear back projection (LBP) algorithm. Experiments were carried out on the four risers using sands as the solids material. The capacitance and differential pressure are measured under the gas superficial velocity from 0.6 m s-1 to 3.0 m s-1 with a step of 0.2 m s-1. The flow regime is investigated according to the solids concentration and differential pressure. The dynamic property of bubbling flows is analyzed theoretically and the performance of the 3D ECT sensors is evaluated. The experimental results show that 3D ECT can be used in the CFB with different risers to predict the hydrodynamics of gas-solids bubbling flows.

The Origin of Chondrites: Metal-Silicate Separation Experiments Under Microgravity Conditions, Experiment 2

NASA Technical Reports Server (NTRS)

Moore, S. R.; Franzen, M.; Benoit, P. H.; Sears, D. W. G.; Holley, A.; Myers, M.; Godsey, R.; Czlapinski, J.

2003-01-01

Chondrites are categorized into different groups by several properties, including the metal-to-silicate ratio. Various processes have been suggested to produce distinct metal/silicate ratios, some based on sorting in the early solar nebular and others occurring after accretion on the parent body. Huang et al. suggested that a weak gravitational field accompanied by degassing, could result in metal/silicate separation on parent bodies. We suggest that asteroids were volatile-rich, at least early in their histories. Spectroscopic evidence from asteroid surfaces indicates that one-third of all asteroids maybe rich in clays and hydrated minerals, similar to carbonaceous chondrites. Internal and/or external heating could have caused volatiles to evaporate and pass through a surface dust layer. Spacecraft images of asteroids show they have a thick regoliths. Housen, and Asphaug and Nolan proposed that even a 10 km diameter asteroid could potentially have a significant regolith. Grain size and grain density sorting could occur in the unconsolidated layer by the process known as fluidization. This process occurs when an upward stream of gas is passed through a bed of particles which are lifted against a gravitational force. Fluidization is commonly used commercially to sort particulates. This type of behavior is based upon the bed, as a whole, and differs from aerodynamic sorting. Two sets of reduced gravity experiments were conducted during parabolic flights aboard NASA's KC-135 aircraft. The first experiment employed 310 tubes of 2.5 cm diameter, containing mixtures of sand and metal grains. A gas source was used to fluidize the mixture at reduced gravity conditions and mixtures were analyzed after the flight. However, this experiment did not allow a description of the fluidization as a function of gravity. A second experiment was conducted on the KC-135 aircraft in the summer of 2001, consisting of two Plexiglas cylinders containing a metal/silicate mixture, and video cameras to record the experiment on tape. Here we summarize this experiment and discusses the implications for metalsilicate separation on asteroid bodies.

Design and operation experience of 230 MWe CFB boilers at Turow power plant in Poland

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

Nowak, W.; Bis, Z.; Laskawiec, J.

The Power Station Turow is located in Bogatynia, Poland, and has operated 10 pulverized coal units each of 200 MW. The plant provided 2000 MW at the lowest cost per kWh in Poland. The Turow units have approached and in some cases already gone beyond their 25--30 year's design life. To meet Poland's new environmental standards, which are now compatible with the EU, Turow decided to replace and upgrade six units (No. 1 to 6) from 200 MW to 230 MW units and remove one unit No. 7. Units No. 8, 9 and 10 were equipped with dry sorbent desulfurizationmore » technology. Units No. 1 and 2 have been replaced with new clean coal circulating fluidized bed technology. The Power Station Turow with six CFB units is to be the largest in the world power station based on fluidized bed technology.« less

In situ fluidization for peat bed rupture, and preliminary economic analysis.

PubMed

Niven, R K; Khalili, N

2002-11-01

This study concerns in situ fluidization (ISF), a new remediation method with potential application to the remediation of NAPL and heavy metal contaminants, by their release from the fluidized zone generated by a water jet. The present study examines the effect of ISF on layers of peat, of significance owing to its role as an important NAPL and metal contaminant trap. Once trapped, such contaminants are not readily accessible by most remedial methods, due to the low permeability and diffusivity of the peat. A simple tank experiment is used to demonstrate rupture of a peat layer by ISF, with removal of the peat as elutriated fines and segregated peat chunks. The application of ISF in the field is then examined by three field trials in uncontaminated sands, in both saturated and unsaturated conditions. Fluidized depths of up to 1.9 m in the saturated zone (with refusal on a peat layer) and 2.5 m in the unsaturated zone (no refusal) were attained, using a 1.9-m-long, 50 mm diameter jet operated at 5-13 1 s(-1). Pulses of dark turbidity and shell fragments in the effluent indicated the rupture of peat and shelly layers. The experiments demonstrate the hydraulic viability of ISF in the field, and its ability to remove peat-based contaminants. The issues of appropriate jet design and water generation during ISF are discussed, followed by a preliminary economic analysis of ISF relative to existing remediation methods.

Bed inventory overturn in a circulating fluid bed riser with pant-leg structure

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

Jinjing Li; Wei Wang; Hairui Yang

2009-05-15

The special phenomenon, nominated as bed inventory overturn, in circulating fluid bed (CFB) riser with pant-leg structure was studied with model calculation and experimental work. A compounded pressure drop mathematic model was developed and validated with the experimental data in a cold experimental test rig. The model calculation results agree well with the measured data. In addition, the intensity of bed inventory overturn is directly proportional to the fluidizing velocity and is inversely proportional to the branch point height. The results in the present study provide significant information for the design and operation of a CFB boiler with pant-leg structure.more » 15 refs., 10 figs., 1 tab.« less

Acoustic fluidization and the scale dependence of impact crater morphology

NASA Technical Reports Server (NTRS)

Melosh, H. J.; Gaffney, E. S.

1983-01-01

A phenomenological Bingham plastic model has previously been shown to provide an adequate description of the collapse of impact craters. This paper demonstrates that the Bingham parameters may be derived from a model in which acoustic energy generated during excavation fluidizes the rock debris surrounding the crater. Experimental support for the theoretical flow law is presented. Although the Bingham yield stress cannot be computed without detailed knowledge of the initial acoustic field, the Bingham viscosity is derived from a simple argument which shows that it increases as the 3/2 power of crater diameter, consistent with observation. Crater collapse may occur in material with internal dissipation Q as low as 100, comparable to laboratory observations of dissipation in granular materials. Crater collapse thus does not require that the acoustic field be regenerated during flow.

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

Mechanistic modelling of fluidized bed drying processes of wet porous granules: a review.

PubMed

Mortier, Séverine Thérèse F C; De Beer, Thomas; Gernaey, Krist V; Remon, Jean Paul; Vervaet, Chris; Nopens, Ingmar

2011-10-01

Fluidized bed dryers are frequently used in industrial applications and also in the pharmaceutical industry. The general incentives to develop mechanistic models for pharmaceutical processes are listed, and our vision on how this can particularly be done for fluidized bed drying processes of wet granules is given. This review provides a basis for future mechanistic model development for the drying process of wet granules in pharmaceutical processes. It is intended for a broad audience with a varying level of knowledge on pharmaceutical processes and mathematical modelling. Mathematical models are powerful tools to gain process insight and eventually develop well-controlled processes. The level of detail embedded in such a model depends on the goal of the model. Several models have therefore been proposed in the literature and are reviewed here. The drying behaviour of one single granule, a porous particle, can be described using the continuum approach, the pore network modelling method and the shrinkage of the diameter of the wet core approach. As several granules dry at a drying rate dependent on the gas temperature, gas velocity, porosity, etc., the moisture content of a batch of granules will reside in a certain interval. Population Balance Model (ling) (PBM) offers a tool to describe the distribution of particle properties which can be of interest for the application. PBM formulation and solution methods are therefore reviewed. In a fluidized bed, the granules show a fluidization pattern depending on the geometry of the gas inlet, the gas velocity, characteristics of the particles, the dryer design, etc. Computational Fluid Dynamics (CFD) allows to model this behaviour. Moreover, turbulence can be modelled using several approaches: Reynolds-averaged Navier-Stokes Equations (RANS) or Large Eddy Simulation (LES). Another important aspect of CFD is the choice between the Eulerian-Lagrangian and the Eulerian-Eulerian approach. Finally, the PBM and CFD frameworks can be integrated, to describe the evolution of the moisture content of granules during fluidized bed drying. Copyright © 2011 Elsevier B.V. All rights reserved.

Joint Long-Range Energy Study for Greater Fairbanks Military Complex

DTIC Science & Technology

2005-02-01

be viewed as a two - stage processor of a fuel or feedstock. The feedstock is first gasified using high-temperature plasma heating sys- tems at...Coal-Fired Boilers with New Circulating Fluidized- Bed Boilers (CFBs). EAFB anticipates replacing two current boilers with two new boilers. This...definition to support DD Form 1391 budget level cost estimates for new coal-fired CHPPs at FWA and EAFB and for two new coal-fired CFBs at EAFB • update

Comparative modeling of biological nutrient removal from landfill leachate using a circulating fluidized bed bioreactor (CFBBR).

PubMed

Eldyasti, Ahmed; Andalib, Mehran; Hafez, Hisham; Nakhla, George; Zhu, Jesse

2011-03-15

Steady state operational data from a pilot scale circulating fluidized bed bioreactor (CFBBR) during biological treatment of landfill leachate, at empty bed contact times (EBCTs) of 0.49, and 0.41 d and volumetric nutrients loading rates of 2.2-2.6 kg COD/(m(3)d), 0.7-0.8 kg N/(m(3)d), and 0.014-0.016 kg P/(m(3)d), was used to calibrate and compare developed process models in BioWin(®) and AQUIFAS(®). BioWin(®) and AQUIFAS(®) were both capable of predicting most of the performance parameters such as effluent TKN, NH(4)-N, NO(3)-N, TP, PO(4)-P, TSS, and VSS with an average percentage error (APE) of 0-20%. BioWin(®) underpredicted the effluent BOD and SBOD values for various runs by 80% while AQUIFAS(®) predicted effluent BOD and SBOD with an APE of 50%. Although both calibrated models, confirmed the advantages of the CFBBR technology in treating the leachate of high volumetric loading and low biomass yields due to the long solid retention time (SRT), both BioWin(®) and AQUIFAS(®) predicted the total biomass and SRT of CFBBR based on active biomass only, whereas in the CFBBR runs both active as well as inactive biomass accumulated. Copyright © 2011 Elsevier B.V. All rights reserved.

Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 1: Process performance and gas product characterization.

PubMed

Thomsen, Tobias Pape; Sárossy, Zsuzsa; Gøbel, Benny; Stoholm, Peder; Ahrenfeldt, Jesper; Frandsen, Flemming Jappe; Henriksen, Ulrik Birk

2017-08-01

Results from five experimental campaigns with Low Temperature Circulating Fluidized Bed (LT-CFB) gasification of straw and/or municipal sewage sludge (MSS) from three different Danish municipal waste water treatment plants in pilot and demonstration scale are analyzed and compared. The gasification process is characterized with respect to process stability, process performance and gas product characteristics. All experimental campaigns were conducted at maximum temperatures below 750°C, with air equivalence ratios around 0.12 and with pure silica sand as start-up bed material. A total of 8600kg of MSS dry matter was gasified during 133h of operation. The average thermal loads during the five experiments were 62-100% of nominal capacity. The short term stability of all campaigns was excellent, but gasification of dry MSS lead to substantial accumulation of coarse and rigid, but un-sintered, ash particles in the system. Co-gasification of MSS with sufficient amounts of cereal straw was found to be an effective way to mitigate these issues as well as eliminate thermal MSS drying requirements. Characterization of gas products and process performance showed that even though gas composition varied substantially, hot gas efficiencies of around 90% could be achieved for all MSS fuel types. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of Methane and Nitrous Oxide Emission Factors for the Biomass Fired Circulating Fluidized Bed Combustion Power Plant

PubMed Central

Cho, Chang-Sang; Sa, Jae-Hwan; Lim, Ki-Kyo; Youk, Tae-Mi; Kim, Seung-Jin; Lee, Seul-Ki; Jeon, Eui-Chan

2012-01-01

This study makes use of this distinction to analyze the exhaust gas concentration and fuel of the circulating fluidized bed (CFB) boiler that mainly uses wood biomass, and to develop the emission factors of Methane (CH4), Nitrous oxide (N2O). The fuels used as energy sources in the subject working sites are Wood Chip Fuel (WCF), RDF and Refused Plastic Fuel (RPF) of which heating values are 11.9 TJ/Gg, 17.1 TJ/Gg, and 31.2 TJ/Gg, respectively. The average concentrations of CH4 and N2O were measured to be 2.78 ppm and 7.68 ppm, respectively. The analyzed values and data collected from the field survey were used to calculate the emission factor of CH4 and N2O exhausted from the CFB boiler. As a result, the emission factors of CH4 and N2O are 1.4 kg/TJ (0.9–1.9 kg/TJ) and 4.0 kg/TJ (2.9–5.3 kg/TJ) within a 95% confidence interval. Biomass combined with the combustion technology for the CFB boiler proved to be more effective in reducing the N2O emission, compared to the emission factor of the CFB boiler using fossil fuel. PMID:23365540

Novel dry-desulfurization process using Ca(OH)2/fly ash sorbent in a circulating fluidized bed.

PubMed

Matsushima, Norihiko; Li, Yan; Nishioka, Masateru; Sadakata, Masayoshi; Qi, Haiying; Xu, Xuchang

2004-12-15

A dry-desulfurization process using Ca(OH)2/fly ash sorbent and a circulating fluidized bed (CFB) was developed. Its aim was to achieve high SO2 removal efficiency without humidification and production of CaSO4 as the main byproduct. The CaSO4 produced could be used to treat alkalized soil. An 83% SO2 removal rate was demonstrated, and a byproduct with a high CaSO4 content was produced through baghouse ash. These results indicated that this process could remove SO2 in flue gas with a high efficiency under dry conditions and simultaneously produce soil amendment. It was shown that NO and NO2 enhanced the SO2 removal rate markedly and that NO2 increased the amount of CaSO4 in the final product more than NO. These results confirmed that the significant effects of NO and NO2 on the SO2 removal rate were due to chain reactions that occurred under favorable conditions. The amount of baghouse ash produced increased as the reaction progressed, indicating that discharge of unreacted Ca(OH)2 from the reactor was suppressed. Hence, unreacted Ca(OH)2 had a long residence time in the CFB, resulting in a high SO2 removal rate. It was also found that 350 degrees C is the optimum reaction temperature for dry desulfurization in the range tested (320-380 degrees C).

Influence of obstacles on bubbles rising in water-saturated sand

NASA Astrophysics Data System (ADS)

Poryles, Raphaël; Varas, Germán; Vidal, Valérie

2017-06-01

This work investigates the dynamics of air rising through a water-saturated sand confined in a Hele- Shaw cell in which a circular obstacle is trapped. The air is injected at constant flow rate through a single nozzle at the bottom center of the cell. Without obstacle, in a similar configuration, previous studies pointed out the existence of a fluidized zone generated by the central upward gas motion which entrains two granular convection rolls on its sides. Here, a circular obstacle which diameter is of the order of the central air channel width is trapped at the vertical of the injection nozzle. We analyze the influence of the obstacle location on the size of the fluidized zone and its impact on the morphology of the central air channel. Finally, we quantify the variations of the granular free surface. Two configurations with multiple obstacles are also considered.

Modeling of the processes of natural and waste water purification in the reactor-clarifier

NASA Astrophysics Data System (ADS)

Primak, O. D.; Skolubovich, Yu. L.; Fedorova, N. N.; Voitov, E. L.

2018-03-01

The results of the filtration process simulation in a reactor-clarifier installation using a suspended loading layer are presented. Calculations were carried out in ANSYS Fluent on the basis of the Navier-Stokes equations supplemented by the equations of the Eulerian model of multiphase taking into account granularity of the particle phase. The unsteady picture of the formation of a fluidized («boiling») layer of particles is obtained. The results of parametric calculations allowing to estimate the effect of the flow velocity, the loading layer thickness, the thickness of sand and other parameters on the fluidized bed structure are presented. The liquid flow rate at which the loading grains are not washed out is determined. The diameter of particles and the height of the loading layer, at which the filter material is suspended and thus normal operation of the plant is ensured, are defined.

Analog laboratory experiments on the influence of substrate roughness on the run out distance of pyroclastic flows

NASA Astrophysics Data System (ADS)

Roche, O.; Chedevile, C.

2012-12-01

We carried out scaled experiments on gas-particles flows propagating on a rough substrate in order to investigate the emplacement of pyroclastic flows. The flows were generated from the release of non-fluidized or gas-fluidized columns of fine (80 μm) glass beads of height of 30 cm into a 3 m-long horizontal channel. The base of the channel was either smooth or was made rough by gluing a monodisperse layer of spherical particles of diameter of 80 μm to 3 mm. We defined the substrate roughness as the size of the glued particles, which corresponded to up to several tens of centimeters when scaled to the natural system. The flow front kinematics and the detailed interactions between the base of the flow and the rough substrate were investigated from high speed videos. We measured systematically the run out distance of the flows, and experiments were repeated 8-10 times for each configuration to obtain a mean value. The run out distance increased with the substrate roughness for both initially non-fluidized and fluidized flows. The run out had a minimum value for a smooth base and was about twice that value for the highest roughness of 3 mm. Analysis of the flow kinematics revealed that the increase in run out was caused by higher front velocities essentially at late stages of emplacement, during which the head of the flows stretched considerably. High speed videos made at the base of the flows showed that their head first slid over the substrate before aggregates of particles fell into the interstices between the particles forming the rough substrate, at a mean speed of several centimeters per second. In contrast, complementary experiments on flows of coarse beads of 350 μm showed that the substrate roughness did not influence their run out, and at the flow base their particles bumped into those of the substrate before falling individually into the interstices. These observations suggest that the positive correlation between the flow run out and the substrate roughness for flows of fine particles could result from two mechanisms. The first was the reduction of the contact area between the flow base and the substrate as the roughness increased because of the reduced number of particles per unit length. The second, main mechanism was auto-fluidization generated as the fine particles falling into the interstices expulsed the air upward at a velocity much larger than the minimum fluidization velocity. This promoted at least partial fluidization or additional pore pressure in case of initially non-fluidized or fluidized flows, respectively. This experimental investigation provides some counterintuitive results and has implication for hazards assessment. Other things being equal, the run out distance of fines-rich pyroclastic flows is expected to increase with the roughness of the terrain on which they propagate.

Investigation of CO 2 capture using solid sorbents in a fluidized bed reactor: Cold flow hydrodynamics

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

Li, Tingwen; Dietiker, Jean -Francois; Rogers, William

2016-07-29

Both experimental tests and numerical simulations were conducted to investigate the fluidization behavior of a solid CO 2 sorbent with a mean diameter of 100 μm and density of about 480 kg/m, which belongs to Geldart's Group A powder. A carefully designed fluidized bed facility was used to perform a series of experimental tests to study the flow hydrodynamics. Numerical simulations using the two-fluid model indicated that the grid resolution has a significant impact on the bed expansion and bubbling flow behavior. Due to the limited computational resource, no good grid independent results were achieved using the standard models asmore » far as the bed expansion is concerned. In addition, all simulations tended to under-predict the bubble size substantially. Effects of various model settings including both numerical and physical parameters have been investigated with no significant improvement observed. The latest filtered sub-grid drag model was then tested in the numerical simulations. Compared to the standard drag model, the filtered drag model with two markers not only predicted reasonable bed expansion but also yielded realistic bubbling behavior. As a result, a grid sensitivity study was conducted for the filtered sub-grid model and its applicability and limitation were discussed.« less

Process of producing liquid hydrocarbon fuels from biomass

DOEpatents

Kuester, James L.

1987-07-07

A continuous thermochemical indirect liquefaction process to convert various biomass materials into diesel-type transportation fuels which fuels are compatible with current engine designs and distribution systems comprising feeding said biomass into a circulating solid fluidized bed gasification system to produce a synthesis gas containing olefins, hydrogen and carbon monoxide and thereafter introducing the synthesis gas into a catalytic liquefaction system to convert the synthesis gas into liquid hydrocarbon fuel consisting essentially of C.sub.7 -C.sub.17 paraffinic hydrocarbons having cetane indices of 50+.

ELECTROSTATIC AIR CLEANING DEVICE AND METHOD

DOEpatents

Silverman, L.; Anderson, D.M.

1961-07-18

A method and apparatus for utilizing friction-charged particulate material from an aerosol are described. A bed of the plastic spheres is prepared, and the aerosol is passed upwardly through the bed at a rate just large enough to maintain the bed in a fluidized state wim over-all circulation of the balls. Wire members criss-crossing through the bed rub against the balls and maintain their surfaces with electrostatic charges. The particulate material in the aerosol adheres to the surfaces of the balls.

Co-firing of oil sludge with coal-water slurry in an industrial internal circulating fluidized bed boiler.

PubMed

Liu, Jianguo; Jiang, Xiumin; Zhou, Lingsheng; Wang, Hui; Han, Xiangxin

2009-08-15

Incineration has been proven to be an alternative for disposal of sludge with its unique characteristics to minimize the volume and recover energy. In this paper, a new fluidized bed (FB) incineration system for treating oil sludge is presented. Co-firing of oil sludge with coal-water slurry (CWS) was investigated in the new incineration system to study combustion characteristics, gaseous pollutant emissions and ash management. The study results show the co-firing of oil sludge with CWS in FB has good operating characteristic. CWS as an auxiliary fuel can flexibly control the dense bed temperatures by adjusting its feeding rate. All emissions met the local environmental requirements. The CO emission was less than 1 ppm or essentially zero; the emissions of SO(2) and NO(x) were 120-220 and 120-160 mg/Nm(3), respectively. The heavy metal analyses of the bottom ash and the fly ash by ICP/AES show that the combustion ashes could be recycled as soil for farming.

Highly Attrition Resistant Zinc Oxide-Based Sorbents for H2S Removal by Spray Drying Technique

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

Ryu, C.K.; Lee, J.B.; Ahn, D.H.

2002-09-19

Primary issues for the fluidized-bed/transport reactor process are high attrition resistant sorbent, its high sorption capacity and regenerability, durability, and cost. The overall objective of this project is the development of a superior attrition resistant zinc oxide-based sorbent for hot gas cleanup in integrated coal gasification combined cycle (IGCC). Sorbents applicable to a fluidized-bed hot gas desulfurization process must have a high attrition resistance to withstand the fast solid circulation between a desulfurizer and a regenerator, fast kinetic reactions, and high sulfur sorption capacity. The oxidative regeneration of zinc-based sorbent usually initiated at greater than 600 C with highly exothermicmore » nature causing deactivation of sorbent as well as complication of sulfidation process by side reaction. Focusing on solving the sorbent attrition and regenerability of zinc oxide-based sorbent, we have adapted multi-binder matrices and direct incorporation of regeneration promoter. The sorbent forming was done with a spray drying technique that is easily scalable to commercial quantity.« less

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.

Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass

NASA Astrophysics Data System (ADS)

Fotovat, Farzam

This thesis focuses on the characterization of hydrodynamics and mixing phenomena in fluidized beds containing mixtures of sand and irregular biomass particles. The first objective of this study is understanding the effect of the large biomass particles on the bubbling characteristics and gas distribution pattern of sand fluidized beds. The second objective is the characterization of mixing/segregation of biomass and sand particles under fluidization conditions. A variety of experimental techniques are employed to study the behavior of two constituting phases of a fluidized bed, i.e., dilute (bubble) and dense (emulsion) phases. Exploring the characteristic fluidization velocities of sand-biomass mixtures unveils that the onset of bubbling in these systems occurs at a higher gas velocity compared to that of the initial fluidization velocity (Uif). The initial bubbling velocity (Uib), the final fluidization velocity ( Uff), and the transition gas velocity from bubbling to turbulent regime (Uc) rise by increasing the fraction of biomass in the mixture. Statistical analysis of the pressure signal at top of the bed reveals that increasing the biomass load hinders the evolution of bubbles at a low gas velocity (U<0.6 m/s), while at high velocities, the bubbling trend of beds containing different fractions of biomass is comparable. The addition of biomass particles to a bed of sand leads to an increase in the mean voidage of the bed; however, the voidage of each phase remains unaffected. It is observed that large biomass particles trigger a break-up of the bubbles, which results in boosting bubbling frequency. The fraction of bubbles at the center of the bed increases with the load of biomass. At the wall region, however, it starts to decrease by adding 2% wt. biomass to pure sand and then increases with the further addition of biomass. The Radioactive Particle Tracking (RPT) technique is implemented in the second section of this work to study the motion and distribution of biomass particles at U=0.36 m/s and U=0.64 m/s. In this regard, an active biomass particle is tracked for a long period of time and its instantaneous position is recorded. The acquired data is then processed to achieve the time-averaged concentration profile of biomass particles. This profile represents the segregation of biomass particles, which tend to accumulate in the upper levels of the bed. Changes in the fraction of biomass with increasing gas velocity are inferred from the local changes of the time-averaged pressure drop values at the top of the bed. To determine the parameters affecting the movement and segregation of biomass particles, their circulatory motion is also scrutinized using the RPT data. The circulation of biomass is impeded when the load of biomass rises at U=0.36 m/s, resulting in a more pronounced segregation of sand and biomass. The opposite trend is observed at U=0.64 m/s. This prompts a more uniform distribution of particles along the bed and brings about a higher degree of mixing. The average rise velocity of biomass is 0.2 times the bubble velocity, regardless of the biomass load or fluidization velocity. A one-dimensional model is proposed to predict the volume fraction of biomass along the bed. Some of the terms of this model are linked to the fluidizing behavior of biomass particles as deduced from the RPT findings. The fluidization of sand and cylindrical biomass particles is also simulated using the BARRACUDA CPFD software, which is based on the Lagrangian-Eulerian approach. Simulation and experimental results are compared in order to evaluate the capability of the numerical approach to predict the bubbling characteristics of the sand-biomass mixture for systems differing in composition and fluidization velocity. The last part of this thesis is devoted to the separation of the main components of the shredded bulky waste. A step-wise process has been developed based on the elutriation and density segregation techniques. After removal of the light and interwoven species of the shredded waste by elutriation, the nonelutriated materials are further separated into two successive fluidization columns. Polypropylene and glass beads are introduced as the fluidization media in these columns in order to make density segregation of the target and not-target components possible. Hence, undesirable combustible matters and hard plastic are separated as the overflow of the first and second fluidization steps. A second elutriation column is also devised to separate and recover fiber and soft plastic. To determine optimal operating conditions, several influential parameters, such as the elutriation velocity and time, the size and density of the fluidization media, and the initial configuration of the feedstock and bed material, are explored. The kinetics of segregation is also derived for both fluidization steps. (Abstract shortened by UMI.).

A quantitative analysis of microcirculation in sore-prone pressure areas on conventional and pressure relief hospital mattresses using laser Doppler flowmetry and tissue spectrophotometry.

PubMed

Rothenberger, Jens; Krauss, Sabrina; Held, Manuel; Bender, Dominik; Schaller, Hans-Eberhard; Rahmanian-Schwarz, Afshin; Constantinescu, Mihai Adrian; Jaminet, Patrick

2014-11-01

Pressure ulcers are associated with severe impairment for the patients and high economic load. With this study we wanted to gain more insight to the skin perfusion dynamics due to external loading. Furthermore, we evaluated the effect of different types of pressure relief mattresses. A total of 25 healthy volunteers were enrolled in the study. Perfusion dynamics of the sacral and the heel area were assessed using the O2C-device, which combines a laser light, to determine blood flow, and white light to determine the relative amount of hemoglobin. Three mattresses were evaluated compared to a hard surface: a standard hospital foam mattress bed, a visco-elastic foam mattress, and an air-fluidized bed. In the heel area, only the air-fluidized bed was able to maintain the blood circulation (mean blood flow of 13.6 ± 6 versus 3.9 ± 3 AU and mean relative amount of hemoglobin of 44.0 ± 14 versus 32.7 ± 12 AU.) In the sacral area, all used mattresses revealed an improvement of blood circulation compared to the hard surface. The results of this study form a more precise pattern of perfusion changes due to external loading on various pressure relief mattresses. This knowledge may reduce the incidence of pressure ulcers and may be an influencing factor in pressure relief mattress selection. Copyright © 2014 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Carbon nanotubes shynthesis in fluidized bed reactor equipped with a cyclone

NASA Astrophysics Data System (ADS)

Setyopratomo, P.; Sudibandriyo, M.; Wulan, P. P. D. K.

2018-03-01

This work aimed to observe the performance of a fluidized bed reactor which was equipped with a cyclone in the synthesis of carbon nanotubes (CNT) by chemical vapor deposition. Liquefied petroleum gas with a constant volumetric flow rate of 1940 cm3/minutes was fed to the reactor as a carbon source, while a combination of metal components of Fe-Co-Mo supported on MgO was used as catalyst. The CNT synthesis was carried out at a reaction temperature which was maintained at around 800 – 850 °C for 1 hour. The CNT yield was decreased sharply when the catalyst feed was increased. The carbon efficiency is directly proportional to the mass of catalyst fed. It was found from the experiment that the mass of as-grown CNT increased in proportion to the increase of the catalyst mass fed. A sharp increase of the mass percentage of carbon nanotubes entrainment happened when the catalyst feed was raised from 3 to 7 grams. Agglomerates of carbon nanotubes have been formed. The agglomerates composed of mutually entangled carbon nanotubes which have an outer diameter range 8 – 14 nm and an inner diameter range 4 – 10 nm, which confirmed that the multi-walled carbon nanotubes were formed in this synthesis. It was found that the mesopores dominate the pore structure of the CNT product and contribute more than 90 % of the total pore volume.

Complex crater formation: Insights from combining observations of shock pressure distribution with numerical models at the West Clearwater Lake impact structure

NASA Astrophysics Data System (ADS)

Rae, A. S. P.; Collins, G. S.; Grieve, R. A. F.; Osinski, G. R.; Morgan, J. V.

2017-07-01

Large impact structures have complex morphologies, with zones of structural uplift that can be expressed topographically as central peaks and/or peak rings internal to the crater rim. The formation of these structures requires transient strength reduction in the target material and one of the proposed mechanisms to explain this behavior is acoustic fluidization. Here, samples of shock-metamorphosed quartz-bearing lithologies at the West Clearwater Lake impact structure, Canada, are used to estimate the maximum recorded shock pressures in three dimensions across the crater. These measurements demonstrate that the currently observed distribution of shock metamorphism is strongly controlled by the formation of the structural uplift. The distribution of peak shock pressures, together with apparent crater morphology and geological observations, is compared with numerical impact simulations to constrain parameters used in the block-model implementation of acoustic fluidization. The numerical simulations produce craters that are consistent with morphological and geological observations. The results show that the regeneration of acoustic energy must be an important feature of acoustic fluidization in crater collapse, and should be included in future implementations. Based on the comparison between observational data and impact simulations, we conclude that the West Clearwater Lake structure had an original rim (final crater) diameter of 35-40 km and has since experienced up to 2 km of differential erosion.

Evaluation of selected chemical processes for production of low-cost silicon, phases 1 and 2

NASA Technical Reports Server (NTRS)

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

1978-01-01

A miniplant, consisting of a 5 cm-diameter fluidized-bed reactor and associated equipment was used to study the deposition parameters, temperature, reactant composition, seed particle size, bed depth, reactant throughput, and methods of reactant introduction. It was confirmed that the permissible range of fluidized-bed temperature was limited at the lower end by zinc condensation (918 C) and at higher temperatures by rapidly decreasing conversion efficiency. Use of a graded bed temperature was shown to increase the conversion efficiency over that obtained in an isothermal bed. Other aspects of the process such as the condensation and fused-salt electrolysis of the ZnCl2 by-product for recycle of zinc and chlorine were studied to provide information required for design of a 50 MT/year experimental facility. In view of the favorable technical and economic indications obtained, it was recommended that construction and operation of the 50 MT/year experimental facility be implemented.

Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.

PubMed

Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar

2015-02-01

An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210 mm diameter and 1600 mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850 °C, 25-31.3 kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37 m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study of Nox Emission Characteristics of a 1025t/h Coal-Fired Circulating Fluidized Bed Boiler

NASA Astrophysics Data System (ADS)

Li, Q. Y.; Mi, Z. D.; Zhang, Q. F.

Measurements of emission are carried out in a 1025t/h CFB boiler. The effect of some factors including coal properties, bed temperature, unit load, excess air on the emission of NOx are investigated. The measurement results show that the N concentration in the coal is dominant parameter to predict the NOx emission from a large-scale CFB boiler. NOx emission from the 1025t/h CFB boiler increases with cyclone temperature and upper pressure drop due to post combustion and external cycle.

Compact CFB: The next generation CFB boiler

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

Utt, J.

1996-12-31

The next generation of compact circulating fluidized bed (CFB) boilers is described in outline form. The following topics are discussed: compact CFB = pyroflow + compact separator; compact CFB; compact separator is a breakthrough design; advantages of CFB; new design with substantial development history; KUHMO: successful demo unit; KUHMO: good performance over load range with low emissions; KOKKOLA: first commercial unit and emissions; KOKKOLA: first commercial unit and emissions; compact CFB installations; next generation CFB boiler; grid nozzle upgrades; cast segmented vortex finders; vortex finder installation; ceramic anchors; pre-cast vertical bullnose; refractory upgrades; and wet gunning.

Thermomechanical CSM analysis of a superheater tube in transient state

NASA Astrophysics Data System (ADS)

Taler, Dawid; Madejski, Paweł

2011-12-01

The paper presents a thermomechanical computational solid mechanics analysis (CSM) of a pipe "double omega", used in the steam superheaters in circulating fluidized bed (CFB) boilers. The complex cross-section shape of the "double omega" tubes requires more precise analysis in order to prevent from failure as a result of the excessive temperature and thermal stresses. The results have been obtained using the finite volume method for transient state of superheater. The calculation was carried out for the section of pipe made of low-alloy steel.

Process of producing liquid hydrocarbon fuels from biomass

DOEpatents

Kuester, J.L.

1987-07-07

A continuous thermochemical indirect liquefaction process is described to convert various biomass materials into diesel-type transportation fuels which fuels are compatible with current engine designs and distribution systems comprising feeding said biomass into a circulating solid fluidized bed gasification system to produce a synthesis gas containing olefins, hydrogen and carbon monoxide and thereafter introducing the synthesis gas into a catalytic liquefaction system to convert the synthesis gas into liquid hydrocarbon fuel consisting essentially of C[sub 7]-C[sub 17] paraffinic hydrocarbons having cetane indices of 50+. 1 fig.

Co-combustion of tannery sludge in a commercial circulating fluidized bed boiler.

PubMed

Dong, Hao; Jiang, Xuguang; Lv, Guojun; Chi, Yong; Yan, Jianhua

2015-12-01

Co-combusting hazardous wastes in existing fluidized bed combustors is an alternative to hazardous waste treatment facilities, in shortage in China. Tannery sludge is a kind of hazardous waste, considered fit for co-combusting with coal in fluidized bedboilers. In this work, co-combustion tests of tannery sludge and bituminous coal were conducted in a power plant in Jiaxing, Zhejiang province. Before that, the combustion behavior of tannery sludge and bituminous were studied by thermogravimetric analysis. Tannery sludge presented higher reactivity than bituminous coal. During the co-combustion tests, the emissions of harmful gases were monitored. The results showed that the pollutant emissions met the Chinese standard except for NOx. The Concentrations of seven trace elements (As, Cr, Cd, Ni, Cu, Pb, Mn) in three exit ash flows (bottom ash in bed, fly ash in filter, and submicrometer aerosol in flue gas) were analyzed. The results of mono-combustion of bituminous coal were compared with those of co-combustion with tannery sludge. It was found that chromium enriched in fly ash. At last, the leachability of fly ash and bottom ash was analyzed. The results showed that most species were almost equal to or below the limits except for As in bottom ashes and Cr in the fly ash of co-combustion test. The concentrations of Cr in leachates of co-combustion ashes are markedly higher than that of coal mono-combustion ashes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Gas Retention, Gas Release, and Fluidization of Spherical Resorcinol-Formaldehyde (sRF) Ion Exchange Resin

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

Gauglitz, Phillip A.; Rassat, Scot D.; Linn, Diana

The Low-Activity Waste Pretreatment System (LAWPS) is being developed to provide treated supernatant liquid from the Hanford tank farms directly to the Low-Activity Waste (LAW) Vitrification Facility at the Hanford Tank Waste Treatment and Immobilization Plant. The design and development of the LAWPS is being conducted by Washington River Protection Solutions, LLC. A key process in LAWPS is the removal of radioactive Cs in ion exchange (IX) columns filled with spherical resorcinol-formaldehyde (sRF) resin. When loaded with radioactive Cs, radiolysis of water in the LAW liquid will generate hydrogen gas. In normal operations, the generated hydrogen is expected to remainmore » dissolved in the liquid and be continuously removed by liquid flow. One accident scenario being evaluated is the loss of liquid flow through the sRF resin bed after it has been loaded with radioactive Cs and hydrogen gas is being generated by radiolysis. For an accident scenario with a loss of flow, hydrogen gas can be retained within the IX column both in the sRF resin bed and below the bottom screen that supports the resin within the column, which creates a hydrogen flammability hazard. Because there is a potential for a large fraction of the retained hydrogen to be released over a short duration as a gas release event, there is a need to quantify the size and rate of potential gas release events. Due to the potential for a large, rapid gas release event, an evaluation of mitigation methods to eliminate the hydrogen hazard is also needed. One method being considered for mitigating the hydrogen hazard during a loss of flow accident is to have a secondary flow system, with two redundant pumps operating in series, that re-circulates liquid upwards through the bed and into a vented break tank where hydrogen gas is released from the liquid and removed by venting the headspace of the break tank. The mechanism for inducing release of gas from the sRF bed is to fluidize the bed, which should allow retained bubbles to rise and be carried to the break tank. The overall conclusion of the testing is that fluidization is an effective method to remove hydrogen gas from a bed of sRF resin, but that a single fluidization velocity that is adequate to release gas in 55 ºC water will over-fluidize sRF resin in most LAW liquids, including both nominal and high-limit LAW simulants used in testing. An upper packed bed can retain hydrogen gas and pose a flammability hazard. Using periodic on:off fluidization, such as 5:55 min. on:off cycles, is effective at releasing gas while not creating an upper packed bed. Note that lengthening the fluidization duration in a one-hour cycle did result in a stable upper packed bed in one case with the nominal LAW simulant, so testing focused on shorter “on” periods which are needed for effective hydrogen release with periodic on:off fluidization« less

Development of a calibration protocol and identification of the most sensitive parameters for the particulate biofilm models used in biological wastewater treatment.

PubMed

Eldyasti, Ahmed; Nakhla, George; Zhu, Jesse

2012-05-01

Biofilm models are valuable tools for process engineers to simulate biological wastewater treatment. In order to enhance the use of biofilm models implemented in contemporary simulation software, model calibration is both necessary and helpful. The aim of this work was to develop a calibration protocol of the particulate biofilm model with a help of the sensitivity analysis of the most important parameters in the biofilm model implemented in BioWin® and verify the predictability of the calibration protocol. A case study of a circulating fluidized bed bioreactor (CFBBR) system used for biological nutrient removal (BNR) with a fluidized bed respirometric study of the biofilm stoichiometry and kinetics was used to verify and validate the proposed calibration protocol. Applying the five stages of the biofilm calibration procedures enhanced the applicability of BioWin®, which was capable of predicting most of the performance parameters with an average percentage error (APE) of 0-20%. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chemical Looping Autothermal Reforming at a 120 kW Pilot Rig

NASA Astrophysics Data System (ADS)

Bofhàr-Nordenkampf, Johannes; Pröll, Tobias; Kolbitsch, Philipp; Hofbauer, Hermann

Chemical looping with selective oxygen transport allows two step combustion or autothermal reforming without mixing of fuel and air. The reactor system consists of two reactors, an air reactor and a fuel reactor with a suitable oxygen carrier that transports the necessary oxygen for operation. In the present study, a highly active nickel based oxygen carrier is tested in a novel dual circulating fluidized bed (DCFB) system at a scale of 120 kW fuel power. The mean particle size of the oxygen carrier is 120 μm and the pilot rig is fueled with natural gas. For the investigated oxygen carrier high CH4 conversion is achieved. Air/fuel ratio is varied at three different fuel reactor temperatures. For chemical looping reforming one can observe synthesis gas composition close to thermodynamic equilibrium. In spite of the fact that no additional steam has been added to the fuel besides the one present through steam fluidization of the loop seals, coke formation does not occur at global stoichiometric air/fuel ratios above 0.46.

Effect of particle size distribution on the hydrodynamics of dense CFB risers

NASA Astrophysics Data System (ADS)

Bakshi, Akhilesh; Khanna, Samir; Venuturumilli, Raj; Altantzis, Christos; Ghoniem, Ahmed

2015-11-01

Circulating Fluidized Beds (CFB) are favorable in the energy and chemical industries, due to their high efficiency. While accurate hydrodynamic modeling is essential for optimizing performance, most CFB riser simulations are performed assuming equally-sized solid particles, owing to limited computational resources. Even though this approach yields reasonable predictions, it neglects commonly observed experimental findings suggesting the strong effect of particle size distribution (psd) on the hydrodynamics and chemical conversion. Thus, this study is focused on the inclusion of discrete particle sizes to represent the psd and its effect on fluidization via 2D numerical simulations. The particle sizes and corresponding mass fluxes are obtained using experimental data in dense CFB riser while the modeling framework is described in Bakshi et al 2015. Simulations are conducted at two scales: (a) fine grid to resolve heterogeneous structures and (b) coarse grid using EMMS sub-grid modifications. Using suitable metrics which capture bed dynamics, this study provides insights into segregation and mixing of particles as well as highlights need for improved sub-grid models.

Numerical Modeling of Reactive Multiphase Flow for FCC and Hot Gas Desulfurization Circulating Fluidized Beds

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

Miller, Aubrey L.

2005-07-01

This work was carried out to understand the behavior of the solid and gas phases in a CFB riser. Only the riser is modeled as a straight pipe. A model with linear algebraic approximation to solids viscosity of the form, {musubs} = 5.34{epsisubs}, ({espisubs} is the solids volume fraction) with an appropriate boundary condition at the wall obtained by approximate momentum balance solution at the wall to acount for the solids recirculation is tested against experimental results. The work done was to predict the flow patterns in the CFB risers from available experimental data, including data from a 7.5-cm-ID CFBmore » riser at the Illinois Institute of Technology and data from a 20.0-cm-ID CFB riser at the Particulate Solid Research, Inc., facility. This research aims at modeling the removal of hydrogen sulfide from hot coal gas using zinc oxide as the sorbent in a circulating fluidized bed and in the process indentifying the parameters that affect the performance of the sulfidation reactor. Two different gas-solid reaction models, the unreacted shrinking core (USC) and the grain model were applied to take into account chemical reaction resistances. Also two different approaches were used to affect the hydrodynamics of the process streams. The first model takes into account the effect of micro-scale particle clustering by adjusting the gas-particle drag law and the second one assumes a turbulent core with pseudo-steady state boundary condition at the wall. A comparison is made with experimental results.« less

Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 2: Evaluation of ash materials as phosphorus fertilizer.

PubMed

Thomsen, Tobias Pape; Hauggaard-Nielsen, Henrik; Gøbel, Benny; Stoholm, Peder; Ahrenfeldt, Jesper; Henriksen, Ulrik B; Müller-Stöver, Dorette Sophie

2017-08-01

The study is part 2 of 2 in an investigation of gasification and co-gasification of municipal sewage sludge in low temperature gasifiers. In this work, solid residuals from thermal gasification and co-gasification of municipal sewage sludge were investigated for their potential use as fertilizer. Ashes from five different low temperature circulating fluidized bed (LT-CFB) gasification campaigns including two mono-sludge campaigns, two sludge/straw mixed fuels campaigns and a straw reference campaign were compared. Experiments were conducted on two different LT-CFBs with thermal capacities of 100kW and 6MW, respectively. The assessment included: (i) Elemental composition and recovery of key elements and heavy metals; (ii) content of total carbon (C) and total nitrogen (N); (iii) pH; (iv) water extractability of phosphorus after incubation in soil; and (v) plant phosphorus response measured in a pot experiment with the most promising ash material. Co-gasification of straw and sludge in LT-CFB gasifiers produced ashes with a high content of recalcitrant C, phosphorus (P) and potassium (K), a low content of heavy metals (especially cadmium) and an improved plant P availability compared to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottom ashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded that LT-CFB gasification and co-gasification is a highly effective way to purify and sanitize sewage sludge for subsequent use in agricultural systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Use of circulating-fluidized-bed combustors in compressed-air energy storage systems

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

Nakhamkin, M.; Patel, M.

1990-07-01

This report presents the result of a study conducted by Energy Storage and Power Consultants (ESPC), with the objective to develop and analyze compressed air energy storage (CAES) power plant concepts which utilize coal-fired circulating fluidized bed combustors (CFBC) for heating air during generating periods. The use of a coal-fired CFBC unit for indirect heating of the compressed air, in lieu of the current turbomachinery combustors, would eliminate the need for expensive premium fuels by a CAES facility. The CAES plant generation heat rate is approximately one-half of that for a conventional steam condensing power plant. Therefore, the required CFBCmore » heat generation capacity and capital costs would be lower per kW of power generation capacity. Three CAES/CFBC concepts were identified as the most promising, and were optimized using specifically developed computerized procedures. These concepts utilize various configurations of reheat turbomachinery trains specifically developed for CAES application as parts of the integrated CAES/CFBC plant concepts. The project team concluded that the optimized CAES/CFBC integrated plant concepts present a potentially attractive alternative to conventional steam generation power plants using CFBC or pulverized coal-fired boilers. A comparison of the results from the economic analysis performed on three concepts suggests that one of them (Concept 3) is the preferred concept. This concept has a two shaft turbomachinery train arrangement, and provides for load management functions by the compressor-electric motor train, and continuous base load operation of the turboexpander-electric generator train and the CFBC unit. 6 refs., 30 figs., 14 tabs.« less

Optimization of Limestone Feed Size of a Pressurized Fluidized Bed Combustor

NASA Astrophysics Data System (ADS)

Shimizu, Tadaaki; Saastamolnen, Jaakko

Limestone attrition is a major cause of loss of limestone during pressurized fluidized bed combustion. In the authors' previous works, the analysis of published results of solid attrition and desulfurization was conducted to determine the attrition rate expression. The specific attrition rate (rate of decrease in diameter) was estimated to be second order with respect to particle diameter in the previous work. This rate expression implies that reduction of feed size of limestone is effective for suppression of loss of limestone by attrition. However, too much grinding of raw limestone will increase the content of fine particles that are readily elutriated by gas stream and do not contribute to the sulfur capture. In this work, modeling works are conducted for particle attrition and desulfurization in order to predict the effect of feed size of limestone on total consumption of limestone and desulfurization is discussed. Optimum particle size to suppress limestone consumption was approximately 0.7 mm (as D p50 ). However, the control of solid drain rate from the bottom was found to have more influence on total limestone consumption rate. Emissions of SO2 from low sulfur coal (S=0.33%) could be sufficiently low irrespective of limestone feed size but SO2 emissions from coals with higher sulfur content than 0.5% were anticipated to increase drastically. Such drastic change in SO2 emissions with the change in sulfur content is attributable to non-linear nature of reaction rate for attrition-enhanced desulfurization by limestone.

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

DOE PAGES

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

2017-05-26

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

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

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Effect of oxygen concentration on viability and metabolism in a fluidized-bed bioartificial liver using ³¹P and ¹³C NMR spectroscopy.

PubMed

Jeffries, Rex E; Gamcsik, Michael P; Keshari, Kayvan R; Pediaditakis, Peter; Tikunov, Andrey P; Young, Gregory B; Lee, Haakil; Watkins, Paul B; Macdonald, Jeffrey M

2013-02-01

Many oxygen mass-transfer modeling studies have been performed for various bioartificial liver (BAL) encapsulation types; yet, to our knowledge, there is no experimental study that directly and noninvasively measures viability and metabolism as a function of time and oxygen concentration. We report the effect of oxygen concentration on viability and metabolism in a fluidized-bed NMR-compatible BAL using in vivo ³¹P and ¹³C NMR spectroscopy, respectively, by monitoring nucleotide triphosphate (NTP) and ¹³C-labeled nutrient metabolites, respectively. Fluidized-bed bioreactors eliminate the potential channeling that occurs with packed-bed bioreactors and serve as an ideal experimental model for homogeneous oxygen distribution. Hepatocytes were electrostatically encapsulated in alginate (avg. diameter, 500 μm; 3.5×10⁷ cells/mL) and perfused at 3 mL/min in a 9-cm (inner diameter) cylindrical glass NMR tube. Four oxygen treatments were tested and validated by an in-line oxygen electrode: (1) 95:5 oxygen:carbon dioxide (carbogen), (2) 75:20:5 nitrogen:oxygen:carbon dioxide, (3) 60:35:5 nitrogen:oxygen:carbon dioxide, and (4) 45:50:5 nitrogen:oxygen:carbon dioxide. With 20% oxygen, β-NTP steadily decreased until it was no longer detected at 11 h. The 35%, 50%, and 95% oxygen treatments resulted in steady β-NTP levels throughout the 28-h experimental period. For the 50% and 95% oxygen treatment, a ¹³C NMR time course (∼5 h) revealed 2-¹³C-glycine and 2-¹³C-glucose to be incorporated into [2-¹³C-glycyl]glutathione (GSH) and 2-¹³C-lactate, respectively, with 95% having a lower rate of lactate formation. ³¹P and ¹³C NMR spectroscopy is a noninvasive method for determining viability and metabolic rates. Modifying tissue-engineered devices to be NMR compatible is a relatively easy and inexpensive process depending on the bioreactor shape.

Experimental Measurements of Heat Transfer through a Lunar Regolith Simulant in a Vibro-Fluidized Reactor Oven

NASA Technical Reports Server (NTRS)

Nayagam, Vedha; Berger, Gordon M.; Sacksteder, Kurt R.; Paz, Aaron

2012-01-01

Extraction of mission consumable resources such as water and oxygen from the planetary environment provides valuable reduction in launch-mass and potentially extends the mission duration. Processing of lunar regolith for resource extraction necessarily involves heating and chemical reaction of solid material with processing gases. Vibrofluidization is known to produce effective mixing and control of flow within granular media. In this study we present experimental results for vibrofluidized heat transfer in lunar regolith simulants (JSC-1 and JSC-1A) heated up to 900 C. The results show that the simulant bed height has a significant influence on the vibration induced flow field and heat transfer rates. A taller bed height leads to a two-cell circulation pattern whereas a single-cell circulation was observed for a shorter height. Lessons learned from these test results should provide insight into efficient design of future robotic missions involving In-Situ Resource Utilization.

Volatile organic compound adsorption in a gas-solid fluidized bed.

PubMed

Ng, Y L; Yan, R; Tsen, L T S; Yong, L C; Liu, M; Liang, D T

2004-01-01

Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas concentration. Concentrations up to 220 ppm for methanol and 75 ppm for isobutane were prepared using this method.

Mass transfer effects in a gasification riser

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

Breault, Ronald W.; Li, Tingwen; Nicoletti, Phillip

2013-07-01

In the development of multiphase reacting computational fluid dynamics (CFD) codes, a number of simplifications were incorporated into the codes and models. One of these simplifications was the use of a simplistic mass transfer correlation for the faster reactions and omission of mass transfer effects completely on the moderate speed and slow speed reactions such as those in a fluidized bed gasifier. Another problem that has propagated is that the mass transfer correlation used in the codes is not universal and is being used far from its developed bubbling fluidized bed regime when applied to circulating fluidized bed (CFB) risermore » reactors. These problems are true for the major CFD codes. To alleviate this problem, a mechanistic based mass transfer coefficient algorithm has been developed based upon an earlier work by Breault et al. This fundamental approach uses the local hydrodynamics to predict a local, time varying mass transfer coefficient. The predicted mass transfer coefficients and the corresponding Sherwood numbers agree well with literature data and are typically about an order of magnitude lower than the correlation noted above. The incorporation of the new mass transfer model gives the expected behavior for all the gasification reactions evaluated in the paper. At the expected and typical design values for the solid flow rate in a CFB riser gasifier an ANOVA analysis has shown the predictions from the new code to be significantly different from the original code predictions. The new algorithm should be used such that the conversions are not over predicted. Additionally, its behaviors with changes in solid flow rate are consistent with the changes in the hydrodynamics.« less

Simulation of hydrodynamics using large eddy simulation-second-order moment model in circulating fluidized beds

NASA Astrophysics Data System (ADS)

Juhui, Chen; Yanjia, Tang; Dan, Li; Pengfei, Xu; Huilin, Lu

2013-07-01

Flow behavior of gas and particles is predicted by the large eddy simulation of gas-second order moment of solid model (LES-SOM model) in the simulation of flow behavior in CFB. This study shows that the simulated solid volume fractions along height using a two-dimensional model are in agreement with experiments. The velocity, volume fraction and second-order moments of particles are computed. The second-order moments of clusters are calculated. The solid volume fraction, velocity and second order moments are compared at the three different model constants.

Method and apparatus for the separation of a gas-solids mixture in a circulating fluidized bed reactor

DOEpatents

Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang

2010-08-10

The system of the present invention includes a centripetal cyclone for separating particulate material from a particulate laden gas solids stream. The cyclone includes a housing defining a conduit extending between an upstream inlet and a downstream outlet. In operation, when a particulate laden gas-solids stream passes through the upstream housing inlet, the particulate laden gas-solids stream is directed through the conduit and at least a portion of the solids in the particulate laden gas-solids stream are subjected to a centripetal force within the conduit.

Characterization of Silicon Nanoparticles Formed from a Fluidized Bed Reactor and Their Incorporation onto Metal-Coated Carbon Fibers

NASA Astrophysics Data System (ADS)

Zbib, Mohamad B.; Sahaym, Uttara; Bahr, David F.

2014-01-01

Enhancing the light trapping using nonwoven arrays of fibers has the potential to improve the photocurrent of silicon solar cells. In this work, amorphous and crystalline Si nanopowders (30-300 nm) were embedded in carbon fibers and fixed in place with electrodeposited nickel. Scanning and transmission electron microscopy techniques have been used to study the morphology of the Si particles and their interactions with the coatings. Two types of nanoparticles are identified, homogeneous nucleated particles (amorphous particles with some crystalline regions) and attrition particles (mostly crystalline products formed from fracture of particles as they grow in a fluidized bed reactor). Using the Brunauer-Emmett-Teller (BET) technique, the surface area and the pore diameter of these agglomerated Si nanoparticles were calculated to be 6.4 m2/g and 9.8 nm, respectively. After embedding the Si particles into the carbon matrix with the metal coatings, the electrical resistivity decreases, suggesting it is possible to enhance the light extraction of silicon solar cells using Si nanoparticles.

Treatment of thin stillage in a high-rate anaerobic fluidized bed bioreactor (AFBR).

PubMed

Andalib, Mehran; Hafez, Hisham; Elbeshbishy, Elsayed; Nakhla, George; Zhu, Jesse

2012-10-01

The primary objective of this work was to investigate the treatability of thin stillage as a by-product of bioethanol production plants using an anaerobic fluidized bed bioreactor (AFBR) employing zeolite with average diameter of (d(m)) of 425-610 μm and specific surface area (SSA) of 26.5m(2)/g as the carrier media. Despite the very high strength of thin stillage with chemical oxygen demand of 130,000 mg TCOD/L and suspended solids of 47,000 mg TSS/L, the AFBR showed up to 88% TCOD and 78% TSS removal at very high organic and solids loading rates (OLR and SLR) of 29 kg COD/m(3)d and 10.5 kg TSS/m(3)d respectively and hydraulic retention time (HRT) of 3.5 days. Methane production rates of up to 160 L/d at the steady state equivalent to 40 L(CH4)/L(thin stillage)d and biogas production rate per reactor volume of 15.8L(gas)/L(reactor)d were achieved. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fluidization quality analyzer for fluidized beds

DOEpatents

Daw, C. Stuart; Hawk, James A.

1995-01-01

A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence.

Fluidization quality analyzer for fluidized beds

DOEpatents

Daw, C.S.; Hawk, J.A.

1995-07-25

A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.

Advanced modeling of nitrogen oxide emissions in circulating fluidized bed combustors: Parametric study of coal combustion and nitrogen compound chemistries

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

Kilpinen, P.; Kallio, S.; Hupa, M.

1999-07-01

This paper describes work-in-progress aimed at developing an emission model for circulating fluidized bed combustors using detailed homogeneous and heterogeneous chemical kinetics. The main emphasis is on nitrogen oxides (NO{sub x}, N{sub 2}O) but also unburned gases (CO, C{sub x}H{sub y}) and sulfur dioxide (SO{sub 2}) will be investigated in the long run. The hydrodynamics is described by a 1.5-dimensional model where the riser is divided into three regions: a dense bubbling bed at the bottom, a vigorously mixed splash zone, and a transport zone. The two latter zones are horizontally split into a core region and an annular region.more » The solids circulation rate is calculated from the known solids inventory and the pressure and mass balances over the entire circulation loop. The solids are divided into classes according to size and type or particle. The model assumes instantaneous fuel devolatilization at the bottom and an even distribution of volatiles in the suspension phase of the dense bed. For addition of secondary air, a complete penetration and an instantaneous mixing with the combustor gases in the core region is assumed. The temperature distribution is assumed to be known, and no energy balance is solved. A comprehensive kinetic scheme of about 300 elementary gas-phase reactions is used to describe the homogeneous oxidation of the volatiles including both hydrocarbon and volatile-nitrogen components (NH{sub 3}, HCN). Heterogeneous char combustion to CO and CO{sub 2}, and char-nitrogen conversion to NO, N{sub 2}O, and N{sub 2} are described by a single particle model that includes 15 reaction steps given in the form of 6 net reaction paths. In the paper, the model is briefly described. A special emphasis is put on the evaluation of chemistry submodels. Modeling results on nitrogen oxides' formation are compared with measured concentration profiles in a 12 MW CFBC riser from literature. The importance of accurate chemistry description on predictions is illustrated by comparing modeling results using detailed kinetics to those obtained when hydrocarbon and volatile-nitrogen oxidation are described with empirical, global kinetic rate expressions from literature. Submodels that need further improvements are discussed.« less

Apparatus and process for controlling fluidized beds

DOEpatents

Rehmat, Amirali G.; Patel, Jitendra G.

1985-10-01

An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

Apparatus for controlling fluidized beds

DOEpatents

Rehmat, Amirali G.; Patel, Jitendra G.

1987-05-12

An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

Asphalt Roofing Shingles Into Energy Project Summary Report

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

Jameson, Rex, PE

2008-04-28

Based on a widely cited September, 1999 report by the Vermont Agency of Natural Resources, nearly 11 million tons of asphalt roofing shingle wastes are produced in the United States each year. Recent data suggests that the total is made up of about 9.4 million tons from roofing tear-offs and about 1.6 million tons from manufacturing scrap. Developing beneficial uses for these materials would conserve natural resources, promote protection of the environment and strengthen the economy. This project explored the feasibility of using chipped asphalt shingle materials in cement manufacturing kilns and circulating fluidized bed (CFB) boilers. A method ofmore » enhancing the value of chipped shingle materials for use as fuel by removing certain fractions for use as substitute raw materials for the manufacture of new shingles was also explored. Procedures were developed to prevent asbestos containing materials from being processed at the chipping facilities, and the frequency of the occurrence of asbestos in residential roofing tear-off materials was evaluated. The economic feasibility of each potential use was evaluated based on experience gained during the project and on a review of the well established use of shingle materials in hot mix asphalt. This project demonstrated that chipped asphalt shingle materials can be suitable for use as fuel in circulating fluidized boilers and cement kilns. More experience would be necessary to determine the full benefits that could be derived and to discover long term effects, but no technical barriers to full scale commercial use of chipped asphalt shingle materials in these applications were discovered. While the technical feasibility of various options was demonstrated, only the use of asphalt shingle materials in hot mix asphalt applications is currently viable economically.« less

Dynamical tests on fiber optic data taken from the riser section of a circulating fluidized bed

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

Taylor, E.M.; Guenther, C.P.; Breault, R.W.

2007-11-01

Dynamical tests have been applied to fiber optic data taken from a cold-flow circulating fluidized bed to characterize flow conditions, identify three time and/or length scales (macro, meso, and micro), and understand the contribution these scales have on the raw data. The characteristic variable analyzed is the raw voltage signal obtained from a fiber-optic probe taken at various axial and radial positions under different loading conditions so that different flow regimes could be attained. These experiments were carried out with the bed material of 812 μm cork particles. The characterization was accomplished through analysis of the distribution of the signalmore » through the third and fourth moments of skewness and excess kurtosis. A generalization of the autocorrelation function known as the average mutual information function was analyzed by examining the function’s first minimum, identifying the point at which successive elements are no longer correlated. Further characterization was accomplished through the correlation dimension, a measure of the complexity of the attractor. Lastly, the amount of disorder of the system is described by a Kolmogorov-type entropy estimate. All six aforementioned tests were also implemented on ten levels of detail coefficients resulting from a discrete wavelet transformation of the same signal as used above. Through this analysis it is possible to identify and describe micro (particle level), meso (clustering or turbulence level), and macro (physical or dimensional level) length scales even though some literature considers these scales inseparable [6]. This investigation also used detail wavelet coefficients in conjunction with ANOVA analysis to show which scales have the most impact on the raw signal resulting from local hydrodynamic conditions.« less

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.

From tissue iron retention to low systemic haemoglobin levels, new pathophysiological biomarkers of human abdominal aortic aneurysm.

PubMed

Martinez-Pinna, R; Lindholt, J S; Madrigal-Matute, J; Blanco-Colio, L M; Esteban-Salan, M; Torres-Fonseca, M M; Lefebvre, T; Delbosc, S; Laustsen, J; Driss, F; Vega de Ceniga, M; Gouya, L; Weiss, G; Egido, J; Meilhac, O; Michel, J-B; Martin-Ventura, J

2014-07-03

Iron deposits are observed in tissue of abdominal aortic aneurysm (AAA) patients, although the underlying mechanisms are not completely elucidated. Therefore we explored circulating markers of iron metabolism in AAA patients, and tested if they could serve as biomarkers of AAA. Increased red blood cell (RBC)-borne iron retention and transferrin, transferrin receptor and ferritin expression was observed in AAA tissue compared to control aorta (immunohistochemistry and western blot). In contrast, decreased circulating iron, transferrin, mean corpuscular haemoglobin concentration (MCHC) and haemoglobin concentration, along with circulating RBC count, were observed in AAA patients (aortic diameter >3 cm, n=114) compared to controls (aortic diameter <3 cm, n=88) (ELISA), whereas hepcidin concentrations were increased in AAA subjects (MS/MS assay). Moreover, iron, transferrin and haemoglobin levels were negatively, and hepcidin positively, correlated with aortic diameter in AAA patients. The association of low haemoglobin with AAA presence or aortic diameter was independent of specific risk factors. Moreover, MCHC negatively correlated with thrombus area in another cohort of AAA patients (aortic diameter 3-5 cm, n=357). We found that anaemia was significantly more prevalent in AAA patients (aortic diameter >5 cm, n=8,912) compared to those in patients with atherosclerotic aorto-iliac occlusive disease (n=17,737) [adjusted odds ratio=1.77 (95% confidence interval: 1.61;1.93)]. Finally, the mortality risk among AAA patients with anaemia was increased by almost 30% [adjusted hazard ratio: 1.29 (95% confidence interval: 1.16;1.44)] as compared to AAA subjects without anaemia. In conclusion, local iron retention and altered iron recycling associated to high hepcidin and low transferrin systemic concentrations could lead to reduced circulating haemoglobin levels in AAA patients. Low haemoglobin levels are independently associated to AAA presence and clinical outcome.

Apparatus for controlling fluidized beds

DOEpatents

Rehmat, A.G.; Patel, J.G.

1987-05-12

An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

Pulse enhanced fluidized bed combustion

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

Mueller, B.

1996-12-31

Information is outlined on pulse enhanced fluidized bed combustion. The following topics are discussed: what is pulse enhanced fluidized bed combustion?; pulse combustors; pulsed atmospheric fluidized bed combustor (PAFBC); advantages of PAFBC; performance advantages; PAFBC facts; and PAFBC contact points.

Micro-CT measurements of tumoral vessels supplied by portal circulation in hepatic colorectal metastasis mouse model.

PubMed

Jun, Hong Young; Lee, Young Hwan; Juhng, Seon Kwan; Lee, Myeung Su; Oh, Jaemin; Yoon, Kwon-Ha

2014-06-01

The purpose of this study was to elucidate the micro CT findings of tumoral vessels supplied by portal circulation during establishment of hepatic metastasis of colorectal cancer in a mouse model. Hepatic metastases were induced in 15 BALB/c mice through the injection of murine colonic adenocarcinoma tumor cells into the mesenteric vein. Micro-CT imaging of the tumoral vessels was obtained to clarify the microvascular architecture. We evaluated the sinusoidal structure, diameter of the tumoral vessels (DTV) and blood vessel density (BVD) according to tumor sizes ranging from 201 to 3,000 µm in diameter. A total of 116 tumors were observed on day 15 after cell injection. The mean diameter of a normal hepatic sinusoid was 11.7 ± 2.0 µm on micro CT. The DTV supplied by the portal vein of tumors measuring 1,001-1,500 µm in diameter was greater than that of tumors 200-1,000 µm in diameter. The mean BVD from the portal vein gradually decrease according to size of tumor from 201 to 3,000 µm in diameter (r(2)  = -0.584, P < 0.01). The characteristics of tumoral vessels supplied by portal circulation during establishment of hepatic colorectal metastases were well visualized with micro-CT imaging. © 2014 Wiley Periodicals, Inc.

Effects of sorbent attrition on utilization

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

Keener, T.C.; Khang, Soon-Jai; Lee, S.K.

1992-03-01

Attrition of surface product levers of sulfite/sulfate may be the key to substantially increasing sorbent utilization in new dry scrubbing processes. This conclusion has been reached from research results obtained from new gas/solid contacting methods such as the Circulating Fluidized Bed Absorber and the Limestone Emission Control method. An additional savings may be reduced by the use of large initial sorbent, particle sizes which greatly reduces the cost of grinding and sorbent preparation. The objectives of project 1.7 were then to study attrition of sorbent particles in a systematic fashion in order to determine how to use attrition to increasemore » sorbent utilization. This was to be carried out by the construction of a bench scale fluidized bed where a series of experiments were to be conducted to measure attrition of lime and limestone samples. This has been accomplished and the project proceeded as anticipated. The results indicate that attrition differs for wet and dry conditions for certain sorbents and that these differences are substantial. Under dry conditions, the results of attrition tests on carefully characterized lime samples indicate that mechanical abrasion is the primary attrition mechanism. The rate of attrition is seen to be similar to a first order chemical reaction where the bed mass (or total surface area) is analagous to reactant concentration. A model for mechanical attrition is presented which expresses the rate constant in an Arrhenius type form proportional to a pseudo attrition activation energy and excess gas energy above a minimum level. The value of this pseudo attrition activation energy for lime has been found to be 106 KJ/KG. For the attrition of wetted lime particles in a fluidized bed. the attrition rate has been found to be directly related to the volumetric flow rate of injected water.« less

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

Mutanen, K.I.

Development of fluidized bed combustion (FBC) was started both in North America and in Europe in the 1960`s. In Europe and especially in Scandinavia the major driving force behind the development was the need to find new more efficient technologies for utilization of low-grade fuels like different biomasses and wastes. Both bubbling fluidized bed (BFB) and circulating fluidized bed (CFB) technologies were under intensive R&D,D efforts and have now advanced to dominating role in industrial and district heating power plant markets in Europe. New advanced CFB designs are now entering the markets. In North America and especially in the USmore » the driving force behind the FBC development was initially the need to utilize different types of coals in a more efficient and environmentally acceptable way. The present and future markets seem to be mainly in biomass and multifuel applications where there is benefit from high combustion efficiency, high fuel flexibility and low emissions such as in the pulp and paper industry. The choice between CFB technology and BFB technology is based on selected fuels, emission requirements, plant size and on technical and economic feasibility. Based on Scandinavian experience there is vast potential in the North American industry to retrofit existing oil fired, pulverized coal fired, chemical recovery or grate fired boilers with FBC systems or to build a new FBC based boiler plant. This paper will present the status of CFB technologies and will compare technical and economic feasibility of CFB technology to CFB technology to BFB and also to other combustion methods. Power plant projects that are using advanced CFB technology e.g. Ahlstrom Pyroflow Compact technology for biomass firing and co-firing of biomass with other fuels will also be introduced.« less

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.

Evaluation of Selected Chemical Processes for Production of Low-cost Silicon, Phase 3

NASA Technical Reports Server (NTRS)

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

1979-01-01

Refinements of the design of the 50 MT/year Experimental Process System Development Unit were made and competitive bids were received from mechanical, electrical, and structural contractors. Bids on most of the equipment were received and cataloged. Emergency procedures were defined to counter a variety of contingencies disclosed in operations and safety reviews. Experimental work with an electrolytic cell for zinc chloride disclosed no significant increase in power efficiency by steps taken to increase electrolyte circulation. On the basis of materials compatibility and permeability tests, 310 stainless steel was chosen for the shell of the fluidized-bed reactor and SiC-coated graphite for the liner.

Neutron activation analysis system

DOEpatents

Taylor, M.C.; Rhodes, J.R.

1973-12-25

A neutron activation analysis system for monitoring a generally fluid media, such as slurries, solutions, and fluidized powders, including two separate conduit loops for circulating fluid samples within the range of radiation sources and detectors is described. Associated with the first loop is a neutron source that emits s high flux of slow and thermal neutrons. The second loop employs a fast neutron source, the flux from which is substantially free of thermal neutrons. Adjacent to both loops are gamma counters for spectrographic determination of the fluid constituents. Other gsmma sources and detectors are arranged across a portion of each loop for deterMining the fluid density. (Official Gazette)

Fluidized bed operations survey summary

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

Lombardi, C.

1996-12-31

A fluidized bed operations survey summary is presented. The survey contains information on: forced outage causes; forced outage concerns ranked numerically; 1996 boiler operation and maintenance (O&M) concerns; 1997 boiler O&M concerns; fluidized bed capacity factor results; and fluidized bed total outage time.

Synergistic erosion/corrosion of superalloys in PFB coal combustor effluent

NASA Technical Reports Server (NTRS)

Benford, S. M.; Zellars, G. R.; Lowell, C. E.

1981-01-01

Two Ni-based superalloys were exposed to the high velocity effluent of a pressurized fluidized bed coal combustor. Targets were 15 cm diameter rotors operating at 40,000 rpm and small flat plate specimens. Above an erosion rate threshold, the targets were eroded to bare metal. The presence of accelerated oxidation at lower erosion rates suggests erosion/corrosion synergism. Various mechanisms which may contribute to the observed oxide growth enhancement include erosive removal of protective oxide layers, oxide and subsurface cracking, and chemical interaction with sulfur in the gas and deposits through damaged surface layers.

Synthesis of fluidized CO2 sorbents based on diamine coordinated to Metal-Organic Frameworks via direct conversion of metal oxides supported on mesoporous silica.

PubMed

Luz, Ignacio; Soukri, Mustapha; Lail, Marty

2018-06-06

A general and efficient method for shaping MOFs into fluidized forms has been developed via direct conversion of metal oxides supported on fluidized mesoporous silica. The resulting fluidized MOF hybrid materials containing diamines coordinated at the open metal sites have been studied as CO2 solid sorbents from post-combustion flue gas showing similar performance than their bulk counterparts. These novel fluidized MOF hybrid materials can be used for other applications involving fluidized bed reactor configurations, in which MOFs have never been considered. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Market assessment of PFBC ash use

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

Bland, A. E.; Brown, T. H., Western Research Institute

1998-01-01

Pressurized fluidized bed combustion (PFBC) of coal is undergoing demonstration in the United States, as well as throughout the world. American Electric Power`s (AEP`s) bubbling PFBC 70 MWe Tidd demonstration program in Ohio and pilot-scale development at Foster Wheeler Energia Oy 10 MWth circulating PFBC at Karhula, Finland, have demonstrated the advantages of PFBC technology. Further technology development in the US is planned with the deployment of the technology at the MacIntosh Clean Coal project in Lakeland, Florida. Development of uses for solid wastes from PFBC coal-fired power systems is being actively pursued as part of the demonstration of PFBCmore » technologies. Ashes collected from Foster Wheeler Energia Oy pilot circulating PFBC tests in Karhula, Finland, operating on (1) low sulfur subbituminous and (2) high sulfur bituminous coal; and ash from the AEP`s high-sulfur bituminous coal-fired bubbling PFBC in Brilliant, Ohio, were evaluated in laboratory and pilot-scale ash use testing at Western Research Institute (WRI).« less

Kinetics of acetaminophen degradation by Fenton oxidation in a fluidized-bed reactor.

PubMed

de Luna, Mark Daniel G; Briones, Rowena M; Su, Chia-Chi; Lu, Ming-Chun

2013-01-01

Acetaminophen (ACT), an analgesic and antipyretic substance, is one of the most commonly detected pharmaceutical compound in surface waters and wastewaters. In this study, fluidized-bed Fenton (FB-Fenton) was used to decompose ACT into its final degradation products. The 1.45-L cylindrical glass reactor had inlet, outlet and recirculating sections. SiO(2) carrier particles were supported by glass beads with 2-4 mm in diameter. ACT concentration was determined by high performance liquid chromatography (HPLC). During the first 40 min of reaction, a fast initial ACT removal was observed and the "two-stage" ACT degradation conformed to a pseudo reaction kinetics. The effects of ferrous ion dosage and [Fe(2+)]/[H(2)O(2)] (FH ratio) were integrated into the derived pseudo second-order kinetic model. A reaction pathway was proposed based on the intermediates detected through SPME/GC-MS. The aromatic intermediates identified were hydroquinone, benzaldehydes and benzoic acids while the non-aromatic substances include alcohols, ketones, aldehydes and carboxylic acids. Rapid initial ACT degradation rate can be accomplished by high initial ferrous ion concentration and/or low FH ratio. Copyright © 2012 Elsevier Ltd. All rights reserved.

Application of spherical silicate to prepare solid dispersion dosage forms with aqueous polymers.

PubMed

Nagane, Kentaro; Kimura, Susumu; Ukai, Koji; Takahashi, Chisato; Ogawa, Noriko; Yamamoto, Hiromitsu

2015-09-30

The objective of this study is to prepare and characterize solid dispersions of nifedipine (NP) using porous spherical silicate micro beads (MB) that were approximately 100 μm in diameter with vinylpyrrolidone/vinyl acetate copolymer (PVP/VA) and a Wurster-type fluidized bed granulator. Compared with previously reported solid dispersion using only MB, the supersaturation of NP dissolved from the proposed system of MB and PVP/VA was maintained during dissolution tests. The proposed system produced a solid dispersion product coated on MB, and morphology was maintained after the coating process to prepare solid dispersion; therefore, the powder characteristics, such as flowability of the proposed solid dispersion product, was tremendously preferable to that of the conventional spray-dried solid dispersions of NP with PVP/VA, expecting to make the consequent manufacturing processes easy for development. Another advantage in the terms of manufacturing is its simple process to prepare solid dispersion by spraying the drug and polymer that were dissolved in an organic solvent onto a MB in a Wurster-type fluidized bed granulator, thus, simplifying the optimization and scale-up with ease. Copyright © 2015 Elsevier B.V. All rights reserved.

Stable carbonous catalyst particles and method for making and utilizing same

DOEpatents

Ganguli, Partha S.; Comolli, Alfred G.

2005-06-14

Stable carbonous catalyst particles composed of an inorganic catalytic metal/metal oxide powder and a carbonaceous binder material are formed having a basic inner substantially uniform-porous carbon coating of the catalytic powder, and may include an outer porous carbon coating layer. Suitable inorganic catalytic powders include zinc-chromite (ZnO/Cr.sub.2 03) and suitable carbonaceous liquid binders having molecular weight of 200-700 include partially polymerized furfuryl alcohol, which are mixed together, shaped and carbonized and partially oxidized at elevated temperature. Such stable carbonous catalyst particles such as 0.020-0.100 inch (0.51-2.54 mm) diameter extrudates, have total carbon content of 2-25 wt. % and improved crush strength of 1.0-5 1b/mn, 50-300 m.sup.2 /g surface area, and can be advantageously utilized in fixed bed or ebullated/fluidized bed reactor operations. This invention also includes method steps for making the stable carbonous catalyst particles having improved particle strength and catalytic activity, and processes for utilizing the active stable carbonous carbon-coated catalysts such as for syn-gas reactions in ebullated/fluidized bed reactors for producing alcohol products and Fischer-Tropsch synthesis liquid products.

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.

Rapid ignition of fluidized bed boiler

DOEpatents

Osborn, Liman D.

1976-12-14

A fluidized bed boiler is started up by directing into the static bed of inert and carbonaceous granules a downwardly angled burner so that the hot gases cause spouting. Air is introduced into the bed at a rate insufficient to fluidize the entire bed. Three regions are now formed in the bed, a region of lowest gas resistance, a fluidized region and a static region with a mobile region at the interface of the fluidized and static regions. Particles are transferred by the spouting action to form a conical heap with the carbonaceous granules concentrated at the top. The hot burner gases ignite the carbonaceous matter on the top of the bed which becomes distributed in the bed by the spouting action and bed movement. Thereafter the rate of air introduction is increased to fluidize the entire bed, the spouter/burner is shut off, and the entire fluidized bed is ignited.

Origin and emplacement of impactites in the Chesapeake Bay impact structure, Virginia, USA

USGS Publications Warehouse

Horton, J. Wright; Gohn, G.S.; Powars, D.S.; Edwards, L.E.

2007-01-01

The late Eocene Chesapeake Bay impact structure, located on the Atlantic margin of Virginia, may be Earth's best-preserved large impact structure formed in a shallow marine, siliciclastic, continental-shelf environment. It has the form of an inverted sombrero in which a central crater ???40 km in diameter is surrounded by a shallower brim, the annular trough, that extends the diameter to ???85 km. The annular trough is interpreted to have formed largely by the collapse and mobilization of weak sediments. Crystalline-clast suevite, found only in the central crater, contains clasts and blocks of shocked gneiss that likely were derived from the fragmentation of the central-uplift basement. The suevite and entrained megablocks are interpreted to have formed from impact-melt particles and crystalline-rock debris that never left the central crater, rather than as a fallback deposit. Impact-modified sediments in the annular trough include megablocks of Cretaceous nonmarine sediment disrupted by faults, fluidized sands, fractured clays, and mixed-sediment intercalations. These impact-modified sediments could have formed by a combination of processes, including ejection into and mixing of sediments in the water column, rarefaction-induced fragmentation and clastic injection, liquefaction and fluidization of sand in response to acoustic-wave vibrations, gravitational collapse, and inward lateral spreading. The Exmore beds, which blanket the entire crater and nearby areas, consist of a lower diamicton member overlain by an upper stratified member. They are interpreted as unstratified ocean-resurge deposits, having depositional cycles that may represent stages of inward resurge or outward anti-resurge flow, overlain by stratified fallout of suspended sediment from the water column. ?? 2008 The Geological Society of America. All rights reserved.

Passive treatment of acid mine drainage using coal combustion by-products and spent mushroom substrate: Results of column study

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

Crisp, T.E.; Nairn, R.W.; Strevett, K.A.

1998-12-31

A column study was conducted to evaluate the feasibility of using of coal combustion by-products (CCB) as alkaline materials in a field scale downflow constructed wetlands for acid mine drainage treatment. Five columns (15.24 cm in diameter and 91.44 cm high) were constructed and filled with a combination of spent mushroom substrate (SMS) and one of three alkaline materials (limestone, hydrated fly ash, or fluidized bed ash). The five mixtures utilized were 10% fluidized bed ash/40% limestone (FBA/LS), 10% fluidized bed ash (FBA), 50% limestone (LS), 50% hydrated fly ash (HFA),m and 50% sieved (>1.5 cm) hydrated fly ash (S.more » HFA) with the remainder as SMS on a w/w basis. Column received synthetic acid mine drainage containing: 400 mg/L iron, 59 mg/L aluminum, 11 mg/L manganese, 50% mg/L magnesium, 40 mg/L calcium, and 1200 mg/L sulfate for 5 months. Anoxic conditions in the influent reservoirs were maintained by a positive nitrogen pressure head. Flow rates of 2.0 mL/minute to each column were maintained by a multichannel peristaltic pump. For all columns, effluent acidity concentrations were less than influent acidity concentration (877{sup {minus}}30, n = 75f). Mean effluent acidity concentrations were 241 mg/L (FBA/LS), 186 mg/L (FBA), 419 mg/L (LS), {minus}28.5 mg/L (HFA), and 351 mg/L (S. HFA), respectively. While all column produced measurable alkalinity, only the HFA column produced a net alkaline discharge. The results of these column studies are applicable to the design and sizing of innovative field scale systems using alkaline-rich CCB`s.« less

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

Gas fluidized-bed stirred media mill

DOEpatents

Sadler, III, Leon Y.

1997-01-01

A gas fluidized-bed stirred media mill is provided for comminuting solid ticles. The mill includes a housing enclosing a porous fluidizing gas diffuser plate, a baffled rotor and stator, a hollow drive shaft with lateral vents, and baffled gas exhaust exit ports. In operation, fluidizing gas is forced through the mill, fluidizing the raw material and milling media. The rotating rotor, stator and milling media comminute the raw material to be ground. Small entrained particles may be carried from the mill by the gas through the exit ports when the particles reach a very fine size.

Staged fluidized bed

DOEpatents

Mallon, R.G.

1983-05-13

The invention relates to oil shale retorting and more particularly to staged fluidized bed oil shale retorting. Method and apparatus are disclosed for narrowing the distribution of residence times of any size particle and equalizing the residence times of large and small particles in fluidized beds. Particles are moved up one fluidized column and down a second fluidized column with the relative heights selected to equalize residence times of large and small particles. Additional pairs of columns are staged to narrow the distribution of residence times and provide complete processing of the material.

Thermal exploitation of wastes with lignite for energy production.

PubMed

Grammelis, Panagiotis; Kakaras, Emmanuel; Skodras, George

2003-11-01

The thermal exploitation of wastewood with Greek lignite was investigated by performing tests in a laboratory-scale fluidized bed reactor, a 1-MW(th) semi-industrial circulating fluidized bed combustor, and an industrial boiler. Blends of natural wood, demolition wood, railroad sleepers, medium-density fiberboard residues, and power poles with lignite were used, and the co-combustion efficiency and the effect of wastewood addition on the emitted pollutants were investigated. Carbon monoxide, sulfur dioxide, and oxides of nitrogen emissions were continuously monitored, and, during the industrial-scale tests, the toxic emissions (polychlorinated dibenzodioxins and dibenzofurans and heavy metals) were determined. Ash samples were analyzed for heavy metals in an inductively coupled plasma-atomic emission spectroscopy spectrophotometer. Problems were observed during the preparation of wastewood, because species embedded with different compounds, such as railway sleepers and demolition wood, were not easily treated. All wastewood blends were proven good fuels; co-combustion proceeded smoothly and homogeneous temperature and pressure profiles were obtained. Although some fluctuations were observed, low emissions of gaseous pollutants were obtained for all fuel blends. The metal element emissions (in the flue gases and the solid residues) were lower than the legislative limits. Therefore, wastewood co-combustion with lignite can be realized, provided that the fuel handling and preparation can be practically performed in large-scale installations.

Effects of parasagittal meningiomas on intracranial venous circulation assessed by the virtual reality technology.

PubMed

Wang, Shousen; Ying, Jianbin; Wei, Liangfeng; Li, Shiqing; Jing, Junjie

2015-01-01

This study is to investigate the compensatory intracranial venous pathways in parasagittal meningiomas (PSM) patients by virtual reality technology. A total of 48 PSM patients (tumor group) and 20 patients with trigeminal neuralgia and hemifacial spasm but without intracranial venous diseases (control group) were enrolled. All patients underwent 3D CE-MRV examination. The 3D reconstructed images by virtual reality technology were used for assessment of diameter and number of intracranial veins, tumor location, venous sinus invasion degree and collateral circulation formation. Diameter of bridging veins in posterior 1/3 superior sagittal sinus (SSS) in tumor group was significantly smaller than that of the control group (P < 0.05). For tumors located in mid 1/3 SSS, diameter of bridging veins and vein of Labbé (VL) in posterior 1/3 SSS decreased significantly (P < 0.05). For tumors located in posterior 1/3 SSS, bridging vein number and transverse sinus (TS) diameter significantly decreased while superficial Sylvian vein (SSV) diameter increased significantly (P < 0.05). Compared with tumor in posterior 1/3 SSS subgroup, number of bridging veins in the tumor in mid 1/3 SSS subgroup increased significantly (P < 0.05). Compared with control group, only the bridging vein number in anterior 1/3 SSS segment in invasion Type 3-4 tumor subgroup decreased significantly (P < 0.05). Diameter of TS and bridging veins in posterior 1/3 SSS segment in sinus invasion Type 5-6 tumor subgroup decreased significantly (P < 0.05). Compared with control group, only the diameter of VL and TS of collateral circulation Grade 1 tumor subgroup decreased significantly (P < 0.05) while in Grade 3 tumor subgroup, TS diameter decreased and SSV diameter increased significantly (P < 0.05). The intracranial blood flow is mainly drained through SSV drainage after SSS occlusion by PSM.

Effects of parasagittal meningiomas on intracranial venous circulation assessed by the virtual reality technology

PubMed Central

Wang, Shousen; Ying, Jianbin; Wei, Liangfeng; Li, Shiqing; Jing, Junjie

2015-01-01

Objective: This study is to investigate the compensatory intracranial venous pathways in parasagittal meningiomas (PSM) patients by virtual reality technology. Methods: A total of 48 PSM patients (tumor group) and 20 patients with trigeminal neuralgia and hemifacial spasm but without intracranial venous diseases (control group) were enrolled. All patients underwent 3D CE-MRV examination. The 3D reconstructed images by virtual reality technology were used for assessment of diameter and number of intracranial veins, tumor location, venous sinus invasion degree and collateral circulation formation. Results: Diameter of bridging veins in posterior 1/3 superior sagittal sinus (SSS) in tumor group was significantly smaller than that of the control group (P < 0.05). For tumors located in mid 1/3 SSS, diameter of bridging veins and vein of Labbé (VL) in posterior 1/3 SSS decreased significantly (P < 0.05). For tumors located in posterior 1/3 SSS, bridging vein number and transverse sinus (TS) diameter significantly decreased while superficial Sylvian vein (SSV) diameter increased significantly (P < 0.05). Compared with tumor in posterior 1/3 SSS subgroup, number of bridging veins in the tumor in mid 1/3 SSS subgroup increased significantly (P < 0.05). Compared with control group, only the bridging vein number in anterior 1/3 SSS segment in invasion Type 3-4 tumor subgroup decreased significantly (P < 0.05). Diameter of TS and bridging veins in posterior 1/3 SSS segment in sinus invasion Type 5-6 tumor subgroup decreased significantly (P < 0.05). Compared with control group, only the diameter of VL and TS of collateral circulation Grade 1 tumor subgroup decreased significantly (P < 0.05) while in Grade 3 tumor subgroup, TS diameter decreased and SSV diameter increased significantly (P < 0.05). Conclusions: The intracranial blood flow is mainly drained through SSV drainage after SSS occlusion by PSM. PMID:26550184

Fluidized bed calciner apparatus

DOEpatents

Owen, Thomas J.; Klem, Jr., Michael J.; Cash, Robert J.

1988-01-01

An apparatus for remotely calcining a slurry or solution feed stream of toxic or hazardous material, such as ammonium diurante slurry or uranyl nitrate solution, is disclosed. The calcining apparatus includes a vertical substantially cylindrical inner shell disposed in a vertical substantially cylindrical outer shell, in which inner shell is disposed a fluidized bed comprising the feed stream material to be calcined and spherical beads to aid in heat transfer. Extending through the outer and inner shells is a feed nozzle for delivering feed material or a cleaning chemical to the beads. Disposed in and extending across the lower portion of the inner shell and upstream of the fluidized bed is a support member for supporting the fluidized bed, the support member having uniform slots for directing uniform gas flow to the fluidized bed from a fluidizing gas orifice disposed upstream of the support member. Disposed in the lower portion of the inner shell are a plurality of internal electric resistance heaters for heating the fluidized bed. Disposed circumferentially about the outside length of the inner shell are a plurality of external heaters for heating the inner shell thereby heating the fluidized bed. Further, connected to the internal and external heaters is a means for maintaining the fluidized bed temperature to within plus or minus approximately 25.degree. C. of a predetermined bed temperature. Disposed about the external heaters is the outer shell for providing radiative heat reflection back to the inner shell.

Fluidized bed boiler feed system

DOEpatents

Jones, Brian C.

1981-01-01

A fluidized bed boiler feed system for the combustion of pulverized coal. Coal is first screened to separate large from small particles. Large particles of coal are fed directly to the top of the fluidized bed while fine particles are first mixed with recycled char, preheated, and then fed into the interior of the fluidized bed to promote char burnout and to avoid elutriation and carryover.

10 CFR 503.10 - Use of fluidized bed combustion not feasible-general requirement for permanent exemptions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Use of fluidized bed combustion not feasible-general... FUELS NEW FACILITIES General Requirements for Exemptions § 503.10 Use of fluidized bed combustion not... finds on a site-specific or generic basis that use of a method of fluidized bed combustion of an...

10 CFR 503.10 - Use of fluidized bed combustion not feasible-general requirement for permanent exemptions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Use of fluidized bed combustion not feasible-general... FUELS NEW FACILITIES General Requirements for Exemptions § 503.10 Use of fluidized bed combustion not... finds on a site-specific or generic basis that use of a method of fluidized bed combustion of an...

10 CFR 503.10 - Use of fluidized bed combustion not feasible-general requirement for permanent exemptions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Use of fluidized bed combustion not feasible-general... FUELS NEW FACILITIES General Requirements for Exemptions § 503.10 Use of fluidized bed combustion not... finds on a site-specific or generic basis that use of a method of fluidized bed combustion of an...

10 CFR 503.10 - Use of fluidized bed combustion not feasible-general requirement for permanent exemptions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Use of fluidized bed combustion not feasible-general... FUELS NEW FACILITIES General Requirements for Exemptions § 503.10 Use of fluidized bed combustion not... finds on a site-specific or generic basis that use of a method of fluidized bed combustion of an...

10 CFR 503.10 - Use of fluidized bed combustion not feasible-general requirement for permanent exemptions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Use of fluidized bed combustion not feasible-general... FUELS NEW FACILITIES General Requirements for Exemptions § 503.10 Use of fluidized bed combustion not... finds on a site-specific or generic basis that use of a method of fluidized bed combustion of an...

Static and transient performance prediction for CFB boilers using a Bayesian-Gaussian Neural Network

NASA Astrophysics Data System (ADS)

Ye, Haiwen; Ni, Weidou

1997-06-01

A Bayesian-Gaussian Neural Network (BGNN) is put forward in this paper to predict the static and transient performance of Circulating Fluidized Bed (CFB) boilers. The advantages of this network over Back-Propagation Neural Networks (BPNNs), easier determination of topology, simpler and time saving in training process as well as self-organizing ability, make this network more practical in on-line performance prediction for complicated processes. Simulation shows that this network is comparable to the BPNNs in predicting the performance of CFB boilers. Good and practical on-line performance predictions are essential for operation guide and model predictive control of CFB boilers, which are under research by the authors.

Pneumatic transportation of dispersed medium through a vertical tube immersed into a fluidized bed

NASA Astrophysics Data System (ADS)

Krasnykh, V. Yu.; Korolev, V. N.; Ostrovskaya, A. V.; Nagornov, S. A.

2013-11-01

We discuss the technical problem of how to transport granular material in a vertical direction from the underlying section of a multistage apparatus containing a fluidized bed to an upper section through tubes immersed into the fluidized bed without additional expenditures of energy. The intensity with which the dispersed medium (a mixture of gas and fuel particles) moves through the tube and the mass flowrate of particles are determined by the ratio between the hydraulic resistances of dispersed medium inside the tube and of the fluidized bed outside of it. In turn, this ratio depends on the fluidization number W (W = w s/ w 0, where w s is the seepage velocity and w 0 is the fluidization commencement velocity) and on the tube immersing depth into the bed.

Fast fluidized bed steam generator

DOEpatents

Bryers, Richard W.; Taylor, Thomas E.

1980-01-01

A steam generator in which a high-velocity, combustion-supporting gas is passed through a bed of particulate material to provide a fluidized bed having a dense-phase portion and an entrained-phase portion for the combustion of fuel material. A first set of heat transfer elements connected to a steam drum is vertically disposed above the dense-phase fluidized bed to form a first flow circuit for heat transfer fluid which is heated primarily by the entrained-phase fluidized bed. A second set of heat transfer elements connected to the steam drum and forming the wall structure of the furnace provides a second flow circuit for the heat transfer fluid, the lower portion of which is heated by the dense-phase fluidized bed and the upper portion by the entrained-phase fluidized bed.

Apparatus and method for controlling heat transfer between a fluidized bed and tubes immersed therein

DOEpatents

Hodges, James L.; Cerkanowicz, Anthony E.

1983-01-01

In a fluidized bed of solid particles having one or more heat exchange tubes immersed therein, the rate of heat transfer between the fluidized particles and a fluid flowing through the immersed heat exchange tubes is controlled by rotating an arcuate shield apparatus about each tube to selectively expose various portions of the tube to the fluidized particles.

Apparatus and method for controlling heat transfer between a fluidized bed and tubes immersed therein

DOEpatents

Hodges, James L.; Cerkanowicz, Anthony E.

1982-01-01

In a fluidized bed of solid particles having one or more heat exchange tubes immersed therein, the rate of heat transfer between the fluidized particles and a fluid flowing through the immersed heat exchange tubes is controlled by rotating an arcuate shield apparatus about each tube to selectively expose various portions of the tube to the fluidized particles.

Simulation of granular and gas-solid flows using discrete element method

NASA Astrophysics Data System (ADS)

Boyalakuntla, Dhanunjay S.

2003-10-01

In recent years there has been increased research activity in the experimental and numerical study of gas-solid flows. Flows of this type have numerous applications in the energy, pharmaceuticals, and chemicals process industries. Typical applications include pulverized coal combustion, flow and heat transfer in bubbling and circulating fluidized beds, hopper and chute flows, pneumatic transport of pharmaceutical powders and pellets, and many more. The present work addresses the study of gas-solid flows using computational fluid dynamics (CFD) techniques and discrete element simulation methods (DES) combined. Many previous studies of coupled gas-solid flows have been performed assuming the solid phase as a continuum with averaged properties and treating the gas-solid flow as constituting of interpenetrating continua. Instead, in the present work, the gas phase flow is simulated using continuum theory and the solid phase flow is simulated using DES. DES treats each solid particle individually, thus accounting for its dynamics due to particle-particle interactions, particle-wall interactions as well as fluid drag and buoyancy. The present work involves developing efficient DES methods for dense granular flow and coupling this simulation to continuum simulations of the gas phase flow. Simulations have been performed to observe pure granular behavior in vibrating beds. Benchmark cases have been simulated and the results obtained match the published literature. The dimensionless acceleration amplitude and the bed height are the parameters governing bed behavior. Various interesting behaviors such as heaping, round and cusp surface standing waves, as well as kinks, have been observed for different values of the acceleration amplitude for a given bed height. Furthermore, binary granular mixtures (granular mixtures with two particle sizes) in a vibrated bed have also been studied. Gas-solid flow simulations have been performed to study fluidized beds. Benchmark 2D fluidized bed simulations have been performed and the results have been shown to satisfactorily compare with those published in the literature. A comprehensive study of the effect of drag correlations on the simulation of fluidized beds has been performed. It has been found that nearly all the drag correlations studied make similar predictions of global quantities such as the time-dependent pressure drop, bubbling frequency and growth. In conclusion, discrete element simulation has been successfully coupled to continuum gas-phase. Though all the results presented in the thesis are two-dimensional, the present implementation is completely three dimensional and can be used to study 3D fluidized beds to aid in better design and understanding. Other industrially important phenomena like particle coating, coal gasification etc., and applications in emerging areas such as nano-particle/fluid mixtures can also be studied through this type of simulation. (Abstract shortened by UMI.)

Microstructure and Mechanical Properties of Heat-Treated B319 Alloy Diesel Cylinder Heads

NASA Astrophysics Data System (ADS)

Chaudhury, S. K.; Apelian, D.; Meyer, P.; Massinon, D.; Morichon, J.

2015-07-01

Microstructure and mechanical properties of B319 alloy diesel cylinder heads were investigated in this study. Cylinder heads were heat treated to T5, T6, and T7 tempers using fluidized bed technology. Three different fluidized beds were used, each to solutionize, quench, and age the castings. For comparative purposes, castings were also aged using conventional forced-air circulation electric-resistance furnace. Effects of processing parameters such as temperature, time, and heating rate on microstructural evolution and mechanical properties namely tensile properties and hardness of B319 alloy castings were studied. The number density and size range of precipitates were measured. Results show that the T5 temper has no effect on eutectic phases such as Si- and Fe-rich intermetallic, and Al2Cu. On contrary, both T6 and T7 tempers result in spherodization of the eutectic Si and partial dissolution of the Al2Cu phase. Prolonged solution heat treatment for 8 hours in fluidized bed results in limited dissolution of the secondary eutectic Al2Cu phase. Aging (T6, T7, and T5) results in precipitation of Al5Cu2Mg8Si6 and Al2Cu phases in B319 alloy. The number density of precipitates in T6 temper is greater than in T7 and T5 tempers. The number density of precipitates is also affected by the duration of solution heat treatment. In general, long solution heat treatment (8 hours) results in greater precipitate density than short solution treatment (2 hours). The distribution of precipitates is inhomogeneous and varied across the dendritic structure. In general, precipitation rate of Al5Cu2Mg8Si6 phase is greater near the periphery of the dendrite as compared to the center. This is because Al5Cu2Mg8Si6 nucleates on Si particle, grain boundaries, and triple junction between recrystallized Al grains and Si particles. Similarly, heterogeneous sites such as grain boundaries and Al/Si interface also act as nucleating sites for the precipitation of Al2Cu phase. In general, the coarsening rate of precipitates near to the periphery of the dendrite is greater than in the center. This is because the Al matrix region close to the eutectic Si particles is subjected to in situ thermal stresses, which is generated due to the thermal mismatch between Al and Si particles. Thermal stress is highest at the Si/Al interface and decreases significantly away from the Al/Si interface. The precipitation and growth rate of the alloy aged in fluidized bed is greater than in conventional furnace. This is because heating rates of casting in fluidized bed (FB) are greater than conventional furnace, which result in greater precipitation rate. This study establishes a correlation between structure, thermal processing, and property of B319 alloy treated to various heat treatments. Reasonably good mechanical properties were obtained in less time using fluidized bed furnace. This work clearly demonstrates the significant potential of FB to save time and energy.

Fluidized-bed bioreactor system for the microbial solubilization of coal

DOEpatents

Scott, C.D.; Strandberg, G.W.

1987-09-14

A fluidized-bed bioreactor system for the conversion of coal into microbially solubilized coal products. The fluidized-bed bioreactor continuously or periodically receives coal and bio-reactants and provides for the production of microbially solubilized coal products in an economical and efficient manner. An oxidation pretreatment process for rendering coal uniformly and more readily susceptible to microbial solubilization may be employed with the fluidized-bed bioreactor. 2 figs.

Staged fluidized bed

DOEpatents

Mallon, Richard G.

1984-01-01

Method and apparatus for narrowing the distribution of residence times of any size particle and equalizing the residence times of large and small particles in fluidized beds. Particles are moved up one fluidized column and down a second fluidized column with the relative heights selected to equalize residence times of large and small particles. Additional pairs of columns are staged to narrow the distribution of residence times and provide complete processing of the material.

Fluidized-bed bioreactor process for the microbial solubiliztion of coal

DOEpatents

Scott, Charles D.; Strandberg, Gerald W.

1989-01-01

A fluidized-bed bioreactor system for the conversion of coal into microbially solubilized coal products. The fluidized-bed bioreactor continuously or periodically receives coal and bio-reactants and provides for the production of microbially solubilized coal products in an economical and efficient manner. An oxidation pretreatment process for rendering coal uniformly and more readily susceptible to microbial solubilization may be employed with the fluidized-bed bioreactor.

CFD Analysis to Calculate the Optimal Air Velocity in Drying Green Tea Process Using Fluidized Bed Dryer

NASA Astrophysics Data System (ADS)

Yohana, Eflita; Nugraha, Afif Prasetya; Diana, Ade Eva; Mahawan, Ilham; Nugroho, Sri

2018-02-01

Tea processing is basically distinguished into three types which black tea, green tea, and oolong tea. Green tea is processed by heating and drying the leaves. Green tea factories in Indonesia are generally using the process of drying by panning the leaves. It is more recommended to use the fluidization process to speed up the drying process as the quality of the tea can be maintained. Bubbling fluidization is expected to occur in this research. It is a process of bubbles are formed in the fluidization. The effectiveness of the drying process in a fluidized bed dryer machine needs to be improved by using a CFD simulation method to proof that umf < u < ut, where the average velocity value is limited by the minimum and the maximum velocity of the calculation the experimental data. The minimum and the maximum velocity value of the fluidization is 0.96 m/s and 8.2 m/s. The result of the simulation obtained that the average velocity of the upper bed part is 1.81 m/s. From the results obtained, it can be concluded that the calculation and the simulation data is in accordance with the condition of bubbling fluidization in fluidized bed dryer.

Solids fluidizer-injector

DOEpatents

Bulicz, Tytus R.

1990-01-01

An apparatus and process for fluidizing solid particles by causing rotary motion of the solid particles in a fluidizing chamber by a plurality of rotating projections extending from a rotatable cylinder end wall interacting with a plurality of fixed projections extending from an opposite fixed end wall and passing the solid particles through a radial feed orifice open to the solids fluidizing chamber on one side and a solid particle utilization device on the other side. The apparatus and process are particularly suited for obtaining intermittent feeding with continual solids supply to the fluidizing chamber. The apparatus and process are suitable for injecting solid particles, such as coal, to an internal combustion engine.

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.

Petropower energia project under way in Chile promises refiner better economics at lower cost

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

NONE

1996-12-31

Construction of the Republic of Chile`s first public/private industrial partnership project is well under way. Ground was broken for the $232-million Petropower Energia Limitada project early this year, shortly after the final contract between the parties - Foster Wheeler Power Systems, Inc. (FWPS); Petrox S.A. Refineria de Petroleo and Empresa Nacional del Petroleo (ENAP) - was signed. The Petropower project, located adjacent to Petrox`s 84,000-b/d refinery in Talcahuano, represents the first project ever to combine petroleum coking technology with cogeneration technology in a single project financing. Petropower is 85% owned by FWPS, 7.5% by ENAP, the Chilean national oil companymore » and parent of Petrox S.A. When completed in mid-1998, the Petropower project will enable Petrox to refine heavier crudes and enhance the refinery`s flexibility and economics. The project will consist of a delayed coking facility (a 12,000-b/d delayed coking unit and a 7,000-b/d hydrotreating plant) and a 67-MW (59 MW net) cogeneration plant. The coke produced will fuel a Foster Wheeler proprietary-design circulating fluidized-bed (CFB) boiler which will generate all the high-pressure steam and electric power needs of the Petrox refinery. This unit will be the first circulating fluidized-bed boiler to be built in Latin America. The cogeneration facility, using limestone as a reagent and equipped with a baghouse, will control SO{sub x} emissions from combustion of the green coke fuel and easily meet all Chilean environmental standards. Moreover, by constructing the cogeneration facility, Petrox will not have to proceed with capital improvements to existing facilities to ensure a reliable source of steam and electricity, resulting in substantial savings for Petrox. The cogeneration plant provides a permanent {open_quotes}disposal{close_quotes} for all coke produced by the delayed coker, thereby solving any future problems of unwanted or excess coke.« less

Radiative heat transfer in strongly forward scattering media of circulating fluidized bed combustors

NASA Astrophysics Data System (ADS)

Ates, Cihan; Ozen, Guzide; Selçuk, Nevin; Kulah, Gorkem

2016-10-01

Investigation of the effect of particle scattering on radiative incident heat fluxes and source terms is carried out in the dilute zone of the lignite-fired 150 kWt Middle East Technical University Circulating Fluidized Bed Combustor (METU CFBC) test rig. The dilute zone is treated as an axisymmetric cylindrical enclosure containing grey/non-grey, absorbing, emitting gas with absorbing, emitting non/isotropically/anisotropically scattering particles surrounded by grey diffuse walls. A two-dimensional axisymmetric radiation model based on Method of Lines (MOL) solution of Discrete Ordinates Method (DOM) coupled with Grey Gas (GG)/Spectral Line-Based Weighted Sum of Grey Gases Model (SLW) and Mie theory/geometric optics approximation (GOA) is extended for incorporation of anisotropic scattering by using normalized Henyey-Greenstein (HG)/transport approximation for the phase function. Input data for the radiation model is obtained from predictions of a comprehensive model previously developed and benchmarked against measurements on the same CFBC burning low calorific value indigenous lignite with high volatile matter/fixed carbon (VM/FC) ratio in its own ash. Predictive accuracy and computational efficiency of nonscattering, isotropic scattering and forward scattering with transport approximation are tested by comparing their predictions with those of forward scattering with HG. GG and GOA based on reflectivity with angular dependency are found to be accurate and CPU efficient. Comparisons reveal that isotropic assumption leads to under-prediction of both incident heat fluxes and source terms for which discrepancy is much larger. On the other hand, predictions obtained by neglecting scattering were found to be in favorable agreement with those of forward scattering at significantly less CPU time. Transport approximation is as accurate and CPU efficient as HG. These findings indicate that negligence of scattering is a more practical choice in solution of the radiative transfer equation (RTE) in conjunction with conservation equations for the system under consideration.

Experimental investigation of ash deposits on convection heating surfaces of a circulating fluidized bed municipal solid waste incinerator.

PubMed

Tang, Zhi; Chen, Xiaoping; Liu, Daoyin; Zhuang, Yaming; Ye, Minghua; Sheng, Hongchan; Xu, Shaojuan

2016-10-01

Incineration of municipal solid waste (MSW) is a waste treatment method which can be sustainable in terms of waste volume reduction, as well as a source of renewable energy. During MSW combustion, increased formation of deposits on convection heating exchanger surfaces can pose severe operational problems, such as fouling, slagging and corrosion. These problems can cause lower heat transfer efficiency from the hot flue gas to the working fluid inside the tubes. A study was performed where experiments were carried out to examine the ash deposition characteristics in a full-scale MSW circulating fluidized bed (CFB) incinerator, using a newly designed deposit probe that was fitted with six thermocouples and four removable half rings. The influence of probe exposure time and probe surface temperature (500, 560, and 700°C) on ash deposit formation rate was investigated. The results indicate that the deposition mass and collection efficiency achieve a minimum at the probe surface temperature of 560°C. Ash particles are deposited on both the windward and leeward sides of the probe by impacting and thermophoretic/condensation behavior. The major inorganic elements present in the ash deposits are Ca, Al and Si. Compared to ash deposits formed on the leeward side of the probe, windward-side ash deposits contain relatively higher Ca and S concentrations, but lower levels of Al and Si. Among all cases at different surface temperatures, the differences in elemental composition of the ash deposits from the leeward side are insignificant. However, as the surface temperature increases, the concentrations of Al, Si, K and Na in the windward-side ash deposits increase, but the Ca concentration is reduced. Finally, governing mechanisms are proposed on the basis of the experimental data, such as deposit morphology, elemental composition and thermodynamic calculations. Copyright © 2016. Published by Elsevier B.V.

Rheological measurements in reduced gravity

NASA Astrophysics Data System (ADS)

Bakhtiyarov, Sayavur I.; Overfelt, Ruel A.

1999-01-01

Rheology of fluidized beds and settling suspensions were studied experimentally in a series of reduced gravity parabolic flights aboard NASA's KC-135 aircraft. Silica sands of two different size distributions were fluidized by air. The slurries were made using silica sand and Glycerol solution. The experimental set up incorporated instrumentation to measure the air flow rate, the pressure drop and the apparent viscosity of the fluidized sand and sand suspensions at a wide range of the shear rates. The fluidization chamber and container had transparent walls to allow visualization of the structure changes involved in fluidization and in Couette flow in reduced gravity. Experiments were performed over a broad range of gravitational accelerations including microgravity and double gravity conditions. The results of the flight and ground experiments reveal significant differences in overall void fraction and hence in the apparent viscosity of fluidized sand and sand suspensions under microgravity as compared to one-g conditions.

Effects of the updated national emission regulation in China on circulating fluidized bed boilers and the solutions to meet them.

PubMed

Li, Jingji; Yang, Hairui; Wu, Yuxin; Lv, Junfu; Yue, Guangxi

2013-06-18

The advantage of circulating fluidized bed (CFB) boilers in China is their ability to utilize low rank coal with low cost emission control. However, the new National Emission Regulation (NER) issued in early 2012 brings much more stringent challenges on the CFB industries, which also causes much attention from other countries. Based on the principle of a CFB boiler and previous operating experience, it is possible for the CFB boilers to meet the new NER and maintain the advantage of low cost emission control, while, more influences should be considered in their design and operation. To meet the requirement of the new NER, the fly ash collector should adopt a bag house or combination of electrostatic precipitator and bag filter to ensure dust emissions of less than 30 mg · Nm(-3). For SO2 emission control, the bed temperature should be strictly lower than 900 °C to maintain high reactivity and pores. The limestone particle size distribution should be ranged within a special scope to optimize the residence time and gas-solid reaction. At the same time, the injecting point should be optimized to ensure fast contact of lime with oxygen. In such conditions, the desulfurization efficiency could be increased more than 90%. For lower sulfur content fuels (<1.5%, referred value based on the heating value of standard coal of China), increasing Ca/S enough could decrease SO2 emissions lower than that of the new NER, 100 mg · Nm(-3). For fuels with sulfur content higher than 1.5%, some simplified systems for flue gas desulfurization, such as flash dryer absorber (FDA), are needed. And the NOx emissions of a CFB can be controlled to less than 100 mg · Nm(-3) without any equipment at a bed temperature lower than 900 °C for fuels with low volatiles content (<12%), while for fuels with high volatiles, selective non-catalytic reduction (SNCR) should be considered. Due to the unique temperature in CFB as well as the circulating ash, the efficiency of SNCR could reach as high as 70%. The Hg emission of CFB is very low for the new NER due to its innate property.

Applications of tribology to determine attrition by wear of particulate solids in CFB systems

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

Bayham, Samuel C.; Breault, Ronald; Monazam, Esmail

In recent years, much attention has been focused on the development of novel technologies for carbon capture and chemicals production that utilize a circulating fluidized bed (CFB) configuration; examples include chemical looping combustion and circulation of temperature swing adsorbents in a CFB configuration for CO 2 capture. A major uncertainty in determining the economic feasibility of these technologies is the required solids makeup rate, which, among other factors, is due to impact and wear attrition at various locations, including standpipes, cyclones, and the gas jets in fluid beds. While correlations have been developed that estimate the attrition rates at thesemore » areas, these correlations are dependent on constants that are uncertain without extensive experiment in the corresponding unit operation. Thus, it is difficult to determine the attrition rate a priori without performing extensive experiments on the materials or scaling up entirely. In this work, the authors outline a methodology for predictive attrition based on fundamental material properties from fields of tribology—specifically, the study of wear—to the knowledge of forces and sliding distances determined from hydrodynamic models to develop basic attrition models for novel CFB systems. The equations are derived for the standpipe and cyclone, which are common components found in CFBs, and the cyclone equation is compared to experimental data of attrition in the literature. The cyclone equation derived in this work results in an abrasion rate based on (1) material properties such as particle density and hardness, (2) inlet velocity, and (3) cyclone geometry. According to this equation, increasing the diameter of the cyclone and the solids inlet velocity tends to increase the rate of abrasion of the catalyst, while decreasing the hardness increases the abrasion rate. The functionality of the increasing attrition rate with velocity increase implies that increasing the efficiency of the cyclone may also increase the attrition rate via abrasion. With modifications to the severity coefficient term to include the solids loading, the cyclone equation derived in this work fits data from Reppenhagen and Werther with a coefficient of determination (R2) of 92%.« less

Applications of tribology to determine attrition by wear of particulate solids in CFB systems

DOE PAGES

Bayham, Samuel C.; Breault, Ronald; Monazam, Esmail

2016-11-03

In recent years, much attention has been focused on the development of novel technologies for carbon capture and chemicals production that utilize a circulating fluidized bed (CFB) configuration; examples include chemical looping combustion and circulation of temperature swing adsorbents in a CFB configuration for CO 2 capture. A major uncertainty in determining the economic feasibility of these technologies is the required solids makeup rate, which, among other factors, is due to impact and wear attrition at various locations, including standpipes, cyclones, and the gas jets in fluid beds. While correlations have been developed that estimate the attrition rates at thesemore » areas, these correlations are dependent on constants that are uncertain without extensive experiment in the corresponding unit operation. Thus, it is difficult to determine the attrition rate a priori without performing extensive experiments on the materials or scaling up entirely. In this work, the authors outline a methodology for predictive attrition based on fundamental material properties from fields of tribology—specifically, the study of wear—to the knowledge of forces and sliding distances determined from hydrodynamic models to develop basic attrition models for novel CFB systems. The equations are derived for the standpipe and cyclone, which are common components found in CFBs, and the cyclone equation is compared to experimental data of attrition in the literature. The cyclone equation derived in this work results in an abrasion rate based on (1) material properties such as particle density and hardness, (2) inlet velocity, and (3) cyclone geometry. According to this equation, increasing the diameter of the cyclone and the solids inlet velocity tends to increase the rate of abrasion of the catalyst, while decreasing the hardness increases the abrasion rate. The functionality of the increasing attrition rate with velocity increase implies that increasing the efficiency of the cyclone may also increase the attrition rate via abrasion. With modifications to the severity coefficient term to include the solids loading, the cyclone equation derived in this work fits data from Reppenhagen and Werther with a coefficient of determination (R2) of 92%.« less

Method for retorting oil shale

DOEpatents

Shang, Jer-Yu; Lui, A.P.

1985-08-16

The recovery of oil from oil shale is provided in a fluidized bed by using a fluidizing medium of a binary mixture of carbon dioxide and 5 steam. The mixture with a steam concentration in the range of about 20 to 75 volume percent steam provides an increase in oil yield over that achievable by using a fluidizing gas of carbon dioxide or steam alone when the mixture contains higher steam concentrations. The operating parameters for the fluidized bed retorted are essentially the same as those utilized with other gaseous fluidizing mediums with the significant gain being in the oil yield recovered which is attributable solely to the use of the binary mixture of carbon dioxide and steam. 2 figs.

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.

Solids fluidizer-injector

DOEpatents

Bulicz, T.R.

1990-04-17

An apparatus and process are described for fluidizing solid particles by causing rotary motion of the solid particles in a fluidizing chamber by a plurality of rotating projections extending from a rotatable cylinder end wall interacting with a plurality of fixed projections extending from an opposite fixed end wall and passing the solid particles through a radial feed orifice open to the solids fluidizing chamber on one side and a solid particle utilization device on the other side. The apparatus and process are particularly suited for obtaining intermittent feeding with continual solids supply to the fluidizing chamber. The apparatus and process are suitable for injecting solid particles, such as coal, to an internal combustion engine. 3 figs.

Fluidized bed heating process and apparatus

NASA Technical Reports Server (NTRS)

McHale, Edward J. (Inventor)

1981-01-01

Capacitive electrical heating of a fluidized bed enables the individual solid particles within the bed to constitute the hottest portion thereof. This effect is achieved by applying an A. C. voltage potential between dielectric coated electrodes, one of which is advantageously the wall of the fluidized bed rejection zone, sufficient to create electrical currents in said particles so as to dissipate heat therein. In the decomposition of silane or halosilanes in a fluidized bed reaction zone, such heating enhances the desired deposition of silicon product on the surface of the seed particles within the fluidized bed and minimizes undesired coating of silicon on the wall of the reaction zone and the homogeneous formation of fine silicon powder within said zone.

Oil shale combustor model developed by Greek researchers

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

Not Available

1986-09-01

Work carried out in the Department of Chemical Engineering at the University of Thessaloniki, Thessaloniki, Greece has resulted in a model for the combustion of retorted oil shale in a fluidized bed combustor. The model is generally applicable to any hot-solids retorting process, whereby raw oil shale is retorted by mixing with a hot solids stream (usually combusted spent shale), and then the residual carbon is burned off the spent shale in a fluidized bed. Based on their modelling work, the following conclusions were drawn by the researchers. (1) For the retorted particle size distribution selected (average particle diameter 1600more » microns) complete carbon conversion is feasible at high pressures (2.7 atmosphere) and over the entire temperature range studied (894 to 978 K). (2) Bubble size was found to have an important effect, especially at conditions where reaction rates are high (high temperature and pressure). (3) Carbonate decomposition increases with combustor temperature and residence time. Complete carbon conversion is feasible at high pressures (2.7 atmosphere) with less than 20 percent carbonate decomposition. (4) At the preferred combustor operating conditions (high pressure, low temperature) the main reaction is dolomite decomposition while calcite decomposition is negligible. (5) Recombination of CO/sub 2/ with MgO occurs at low temperatures, high pressures, and long particle residence times.« less

Control of bed height in a fluidized bed gasification system

DOEpatents

Mehta, Gautam I.; Rogers, Lynn M.

1983-12-20

In a fluidized bed apparatus a method for controlling the height of the fdized bed, taking into account variations in the density of the bed. The method comprises taking simultaneous differential pressure measurements at different vertical elevations within the vessel, averaging the differential pressures, determining an average fluidized bed density, then periodically calculating a weighting factor. The weighting factor is used in the determination of the actual bed height which is used in controlling the fluidizing means.

Increased Arterial Diameters in the Posterior Cerebral Circulation in Men with Fabry Disease

PubMed Central

Üçeyler, Nurcan; Homola, György A.; Guerrero González, Hans; Kramer, Daniela; Wanner, Christoph; Weidemann, Frank; Solymosi, László; Sommer, Claudia

2014-01-01

A high load of white matter lesions and enlarged basilar arteries have been shown in selected patients with Fabry disease, a disorder associated with an increased stroke risk. We studied a large cohort of patients with Fabry disease to differentially investigate white matter lesion load and cerebral artery diameters. We retrospectively analyzed cranial magnetic resonance imaging scans of 87 consecutive Fabry patients, 20 patients with ischemic stroke, and 36 controls. We determined the white matter lesion load applying the Fazekas score on fluid-attenuated inversion recovery sequences and measured the diameters of cerebral arteries on 3D-reconstructions of the time-of-flight-MR-angiography scans. Data of different Fabry patient subgroups (males – females; normal – impaired renal function) were compared with data of patients with stroke and controls. A history of stroke or transient ischemic attacks was present in 4/30 males (13%) and 5/57 (9%) females with Fabry disease, all in the anterior circulation. Only one man with Fabry disease showed confluent cerebral white matter lesions in the Fazekas score assessment (1%). Male Fabry patients had a larger basilar artery (p<0.01) and posterior cerebral artery diameter (p<0.05) compared to male controls. This was independent of disease severity as measured by renal function and did not lead to changes in arterial blood flow properties. A basilar artery diameter of >3.2 mm distinguished between men with Fabry disease and controls (sensitivity: 87%, specificity: 86%, p<0.001), but not from stroke patients. Enlarged arterial diameters of the posterior circulation are present only in men with Fabry disease independent of disease severity. PMID:24475221

Multivariate analyses of crater parameters and the classification of craters

NASA Technical Reports Server (NTRS)

Siegal, B. S.; Griffiths, J. C.

1974-01-01

Multivariate analyses were performed on certain linear dimensions of six genetic types of craters. A total of 320 craters, consisting of laboratory fluidization craters, craters formed by chemical and nuclear explosives, terrestrial maars and other volcanic craters, and terrestrial meteorite impact craters, authenticated and probable, were analyzed in the first data set in terms of their mean rim crest diameter, mean interior relief, rim height, and mean exterior rim width. The second data set contained an additional 91 terrestrial craters of which 19 were of experimental percussive impact and 28 of volcanic collapse origin, and which was analyzed in terms of mean rim crest diameter, mean interior relief, and rim height. Principal component analyses were performed on the six genetic types of craters. Ninety per cent of the variation in the variables can be accounted for by two components. Ninety-nine per cent of the variation in the craters formed by chemical and nuclear explosives is explained by the first component alone.

Effects of sorbent attrition on utilization. Final report, June 1, 1990--June 30, 1991

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

Keener, T.C.; Khang, Soon-Jai; Lee, S.K.

1992-03-01

Attrition of surface product levers of sulfite/sulfate may be the key to substantially increasing sorbent utilization in new dry scrubbing processes. This conclusion has been reached from research results obtained from new gas/solid contacting methods such as the Circulating Fluidized Bed Absorber and the Limestone Emission Control method. An additional savings may be reduced by the use of large initial sorbent, particle sizes which greatly reduces the cost of grinding and sorbent preparation. The objectives of project 1.7 were then to study attrition of sorbent particles in a systematic fashion in order to determine how to use attrition to increasemore » sorbent utilization. This was to be carried out by the construction of a bench scale fluidized bed where a series of experiments were to be conducted to measure attrition of lime and limestone samples. This has been accomplished and the project proceeded as anticipated. The results indicate that attrition differs for wet and dry conditions for certain sorbents and that these differences are substantial. Under dry conditions, the results of attrition tests on carefully characterized lime samples indicate that mechanical abrasion is the primary attrition mechanism. The rate of attrition is seen to be similar to a first order chemical reaction where the bed mass (or total surface area) is analagous to reactant concentration. A model for mechanical attrition is presented which expresses the rate constant in an Arrhenius type form proportional to a pseudo attrition activation energy and excess gas energy above a minimum level. The value of this pseudo attrition activation energy for lime has been found to be 106 KJ/KG. For the attrition of wetted lime particles in a fluidized bed. the attrition rate has been found to be directly related to the volumetric flow rate of injected water.« less

Microgravity and Hypogravity Compatible Methods for the Destruction of Solid Wastes by Magnetically Assisted Gasification

NASA Technical Reports Server (NTRS)

Atwater, James E.; Akse, James R.; Wheeler, Richard R., Jr.; Jovanovic, Goran N.; Pinto-Espinoza, Joaquin; Reed, Brian; Sornchamni, Thana

2003-01-01

This report summarizes a three-year collaborative effort between researchers at UMPQUA Research Company (URC) and the Chemical Engineering Department at Oregon State University (OSU). The Magnetically Assisted Gasification (MAG) concept was originally conceived as a microgravity and hypogravity compatible means for the decomposition of solid waste materials generated aboard spacecraft, lunar and planetary habitations, and for the recovery of potentially valuable resources. While a number of methods such as supercritical water oxidation (SCW0), fluidized bed incineration, pyrolysis , composting and related biological processes have been demonstrated for the decomposition of solid wastes, none of these methods are particularly well- suited for employment under microgravity or hypogravity conditions. For example, fluidized bed incineration relies upon a balance between drag forces which the flowing gas stream exerts upon the fluidization particles and the opposing force of gravity. In the absence of gravity, conventional fluidization cannot take place. Hypogravity operation can also be problematic for conventional fluidized bed reactors, because the various factors which govern fluidization phenomena do not all scale linearly with gravity. For this reason it may be difficult to design and test fluidized bed reactors in lg, which are intended to operate under different gravitational conditions. However, fluidization can be achieved in microgravity (and hypogravity) if a suitable replacement force to counteract the forces between fluid and particles can be found. Possible alternatives include: centripetal force, electric fields, or magnetic fields. Of these, magnetic forces created by the action of magnetic fields and magnetic field gradients upon ferromagnetic media offer the most practical approach. The goal of this URC-OSU collaborative effort was to develop magnetic hardware and methods to control the degree of fluidization (or conversely consolidation) of granular ferromagnetic media and to employ these innovations in sequential filtration and fluidized bed processes for the segregation and decomposition of solid waste materials, and for the concentration and collection of inorganic residue (ash). This required the development of numerous enabling technologies and tools.

Fluidization and drying of biomass particles in a vibrating fluidized bed with pulsed gas flow

DOE PAGES

Jia, Dening; Cathary, Océane; Peng, Jianghong; ...

2015-10-01

Fluidization of biomass particles in the absence of inert bed materials has been tested in a pulsed fluidized bed with vibration, with the pulsation frequency ranging from 033 to 6.67 Hz. Intermittent fluidization at 033 Hz and apparently 'normal' fluidization at 6.67 Hz with regular bubble patterns were observed. Pulsation has proven to be effective in overcoming the bridging of irregular biomass particles induced by strong inter-particle forces. The vibration is only effective when the pulsation is inadequate, either at too low a frequency or too low in amplitude. We dried biomass in order to quantify the effectiveness of gasmore » pulsation for fluidized bed dryers and torrefiers in terms of gas-solid contact efficiency and heat and mass transfer rates. Furthermore, the effects of gas flow rate, bed temperature, pulsation frequency and vibration intensity on drying performance have been systematically investigated. While higher temperature and gas flow rate are favored in drying, there exists an optimal range of pulsation frequency between 0.75 Hz and 1.5 Hz where gas-solid contact is enhanced in both the constant rate drying and falling rate drying periods.« less

The Large Impact Process Inferred from the Geology of Lunar Multiring Basins

NASA Technical Reports Server (NTRS)

Spudis, Paul D.

1994-01-01

The study of the geology of multiring impact basins on the Moon over the past ten years has given us a rudimentary understanding of how these large structures have formed and evolved on the Moon and other bodies. Two-ring basins on the Moon begin to form at diameters of about 300 km; the transition diameter at which more than two rings appear is uncertain, but it appears to be between 400 and 500 km in diameter. Inner rings tend to be made up of clusters or aligned segments of massifs and are arranged into a crudely concentric pattern; scarp-like elements may or may not be present. Outer rings are much more scarp-like and massifs are rare to absent. Basins display textured deposits, interpreted as ejecta, extending roughly an apparent basin radius exterior to the main topographic rim. Ejecta may have various morphologies, ranging from wormy and hummocky deposits to knobby surfaces; the causes of these variations are not known, but may be related to the energy regime in which the ejecta are deposited. Outside the limits of the textured ejecta are found both fields of satellitic craters (secondaries) and light plains deposits. Impact melt sheets are observed on the floors of relatively unflooded basins. Samples of impact melts from lunar basins have basaltic major-element chemistry, characterized by K, rare-earth elements (REE), P, and other trace elements of varying concentration (KREEP); ages are between 3.8 and 3.9 Ga. These lithologies cannot be produced through the fusion of known pristine (plutonic) rock types, suggesting the occurrence of unknown lithologies within the Moon. These melts were probably generated at middle to lower crustal levels. Ejecta compositions, preservation of pre-basin topography, and deposit morphologies all indicate that the excavation cavity of multiring basins is between about 0.4 and 0.6 times the diameter of the apparent crater diameter. Basin depths of excavation can be inferred from the composition of basin ejecta. A variety of mechanisms has been proposed to account for the formation of basin rings but none of them are entirely plausible. Mechanisms can be divided into two broad groups: (1) forcible uplift due to fluidization of the target; (2) concentric, brittle, fracturing and failure of the target, on regional (megaterraces) to global scales (lithospheric fracturing). Most basin rings are spaced at a constant factor on all planets. Evidence supports divergent ringforming models, so it may be that the ring-locating mechanism differs from the ring-forming mechanism. Thus, large-scale crustal foundering (megaterracing) could occur along concentric zones of weakness created by some type of resonant wave mechanism (fluidization and uplift); such immediate crustal adjustment could then be followed by long-term adjustment of the fractured lithosphere.

Fluidized bed injection assembly for coal gasification

DOEpatents

Cherish, Peter; Salvador, Louis A.

1981-01-01

A coaxial feed system for fluidized bed coal gasification processes including an inner tube for injecting particulate combustibles into a transport gas, an inner annulus about the inner tube for injecting an oxidizing gas, and an outer annulus about the inner annulus for transporting a fluidizing and cooling gas. The combustibles and oxidizing gas are discharged vertically upward directly into the combustion jet, and the fluidizing and cooling gas is discharged in a downward radial direction into the bed below the combustion jet.

Coal-feeding mechanism for a fluidized bed combustion chamber

DOEpatents

Gall, Robert L.

1981-01-01

The present invention is directed to a fuel-feeding mechanism for a fluidized bed combustor. In accordance with the present invention a perforated conveyor belt is utilized in place of the fixed grid normally disposed at the lower end of the fluidized bed combustion zone. The conveyor belt is fed with fuel, e.g. coal, at one end thereof so that the air passing through the perforations dislodges the coal from the belt and feeds the coal into the fluidized zone in a substantially uniform manner.

CFD Modeling of a CFB Riser Using Improved Inlet Boundary Conditions

NASA Astrophysics Data System (ADS)

Peng, B. T.; Zhang, C.; Zhu, J. X.; Qi, X. B.

2010-03-01

A computational fluid dynamics (CFD) model based on Eulerian-Eulerian approach coupled with granular kinetics theory was adopted to investigate the hydrodynamics and flow structures in a circulating fluidized bed (CFB) riser column. A new approach to specify the inlet boundary conditions was proposed in this study to simulate gas-solids flow in CFB risers more accurately. Simulation results were compared with the experimental data, and good agreement between the numerical results and experimental data was observed under different operating conditions, which indicates the effectiveness and accuracy of the CFD model with the proposed inlet boundary conditions. The results also illustrate a clear core annulus structure in the CFB riser under all operating conditions both experimentally and numerically.

Study of CFB Simulation Model with Coincidence at Multi-Working Condition

NASA Astrophysics Data System (ADS)

Wang, Z.; He, F.; Yang, Z. W.; Li, Z.; Ni, W. D.

A circulating fluidized bed (CFB) two-stage simulation model was developed. To realize the model results coincident with the design value or real operation value at specified multi-working conditions and with capability of real-time calculation, only the main key processes were taken into account and the dominant factors were further abstracted out of these key processes. The simulation results showed a sound accordance at multi-working conditions, and confirmed the advantage of the two-stage model over the original single-stage simulation model. The combustion-support effect of secondary air was investigated using the two-stage model. This model provides a solid platform for investigating the pant-leg structured CFB furnace, which is now under design for a supercritical power plant.

Charged anaesthetics alter LM-fibroblast plasma-membrane enzymes by selective fluidization of inner or outer membrane leaflets.

PubMed Central

Sweet, W D; Schroeder, F

1986-01-01

The functional consequences of the differences in lipid composition and structure between the two leaflets of the plasma membrane were investigated. Fluorescence of 1,6-diphenylhexa-1,3,5-triene(DPH), quenching, and differential polarized phase fluorimetry demonstrated selective fluidization by local anaesthetics of individual leaflets in isolated LM-cell plasma membranes. As measured by decreased limiting anisotropy of DPH fluorescence, cationic (prilocaine) and anionic (phenobarbital and pentobarbital) amphipaths preferentially fluidized the cytofacial and exofacial leaflets respectively. Unlike prilocaine, procaine, also a cation, fluidized both leaflets of these membranes equally. Pentobarbital stimulated 5'-nucleotidase between 0.1 and 5 mM and inhibited at higher concentrations, whereas phenobarbital only inhibited, at higher concentrations. Cationic drugs were ineffective. Two maxima of (Na+ + K+)-ATPase activation were obtained with both anionic drugs. Only one activation maximum was obtained with both cationic drugs. The maximum in activity below 1 mM for all four drugs clustered about a single limiting anisotropy value in the cytofacial leaflet, whereas there was no correlation between activity and limiting anisotropy in the exofacial leaflets. Therefore, although phenobarbital and pentobarbital below 1 mM fluidized the exofacial leaflet more than the cytofacial leaflet, the smaller fluidization in the cytofacial leaflet was functionally significant for (Na+ + K+)-ATPase. Mg2+-ATPase was stimulated at 1 mM-phenobarbital, unaffected by pentobarbital and slightly stimulated by both cationic drugs at concentrations fluidizing both leaflets. Thus the activity of (Na+ + K+)-ATPase was highly sensitive to selective fluidization of the leaflet containing its active site, whereas the other enzymes examined were little affected by fluidization of either leaflet. PMID:3028369

Hybrid Encapsulated Ionic Liquids for Post-Combustion Carbon Dioxide (CO 2) Capture

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

Brennecke, Joan F; Degnan, Jr, Thomas Francis; McCready, Mark J.

Ionic liquids (ILs) and Phase Change Ionic Liquids (PCILs) are excellent materials for selective removal of carbon dioxide from dilute post-combustion streams. However, they are typically characterized as having high viscosities, which impairs their effectiveness due to mass transfer limitations, caused by the high viscosities. In this project, we are examining the benefits of encapsulating ILs and PCILs in thin polymeric shells to produce particles of approximately 100 to 600 µm in diameter that can be used in a fluidized bed absorber. The particles are produced by microencapsulation of the ILs and PCILs in CO 2-permeable polymer shells. Here wemore » report on the encapsulation of the IL and PCIL materials, thermodynamic testing of the encapsulated materials, mass transfer measurements in both a fluidized bed and a packed bed, determination of the effect of impurities (SO 2, NO x and water) on the free and encapsulated IL and PCIL, recyclability of the CO 2 uptake, selection and synthesis of kg quantities of the IL and PCIL, identification of scale-up methods for encapsulation and production of a kg quantity of the PCIL, construction and shakedown of the laboratory scale unit to test the encapsulated particles for CO 2 capture ability and efficiency, use of our mass transfer model to predict mass transfer and identify optimal properties of the encapsulated particles, and initial testing of the encapsulated particles in the laboratory scale unit. We also show our attempts at developing shell materials that are resistant to water permeation. Overall, we have shown that the selected IL and PCIL can be successfully encapsulated in polymer shells and the methods scaled up to production levels. The IL/PCIL and encapsulated IL/PCIL react irreversibly with SO 2 and NO x so the CO 2 capture unit would need to be placed after the flue gas desulfurization and NO x reduction units. However, the reaction with CO 2 in the presence of water is completely reversible. Therefore, it is not necessary to exclude water from the capsules. Mass transfer in the fluidized and packed beds confirm that the fluidized bed arrangement is preferred and that the mass transfer can be predicted accurately by the rate based model that we have developed. Absorption and desorption experiments in the laboratory scale unit show good uptake and recyclability.« 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)

Obseration of flow regime transition in CFB riser using an LDV

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

Yue, Paul C.; Mei, Joseph S.; Shadle, Lawrence J.

2011-01-01

The solids flow in a circulating fluidized bed (CFB) riser is often described to have a core-annular structure. For a given superficial gas velocity, at the initial introduction of solids into a riser a flow structure of dilute upflow regime exists. Continuing to increase the solids flow in the riser transitions the flow structure to the core-annular flow regime. However, with further increase of solids flow a condition is reached, depending on the superficial gas velocity, where all the solids across the riser cross section flow upwards, even those at the wall. When the solids flux, solids fraction and gasmore » velocity are relatively high, such a condition is described as the dense phase suspense upflow (DSU) regime. In this paper we report our observations of these flow regime transitions by using a laser Doppler velocimeter (LDV) to monitor the upward and downward particle flow velocities at and near the riser wall of the National Energy Technology Laboratory’s 30.4 centimeters diameter CFB cold flow model. The particles were high density polyethylene (PPE) spheres with a Sauter mean diameter of 861 micron and a density of 800 kg/m3. Three superficial gas velocities of 6.55 m/s, 10.67 m/s and 13.72 m/s were used in this study. For the case of superficial gas velocity 6.55 m/s, the experimental data show that the transition from dilute upflow to core-annular flow occurred when the solids flux was about 7 kg/m{sup 2}-s and the transition from core-annular flow to dense suspension upflow was about 147 kg/m{sup 2}-s. As the superficial gas velocity was increased to 10.67 m/s the corresponding flow regime transitions were at 34 kg/m{sup 2}-s and 205 kg/m{sup 2}-s, respectively. For the case of superficial gas velocity of 13.72 m/s the data showed no distinct transition of flow regimes. The particles were all upflow for the range of solids fluxes from 10 kg/m{sup 2}-s to 286 kg/m{sup 2}-s.« less

Elutriation characteristics of fine particles from bubbling fluidized bed incineration for sludge cake treatment.

PubMed

Chang, Yu-Min; Chou, Chih-Mei; Su, Kuo-Tung; Hung, Chao-Yang; Wu, Chao-Hsiung

2005-01-01

In this study, measurements of elutriation rate were carried out in a bench scale bubbling fluidized bed incinerator, which was used to combust sludge cake. The particle size distribution and ignition loss were analyzed to study the elutriation characteristics of bubbling fluidized bed incineration. Drawn from the experimental data, the elutriation rate constant K(i)* for fine particles were obtained and correlated with parameters. It was found that most of the solid particles (about 95%) elutriated came from the fluidized medium (inorganic matters), but few came from unburned carbon particles or soot (about 5%). Finally, this paper lists a comparison of K(i)* between this study and the published prediction equations derived or studied in non-incineration modes of fluidized bed. A new and modified correlation is proposed here to estimate the elutriation rate of fine particles emitted from a bubbling fluidized bed incinerator. Primary operation variables (superficial gas velocity and incineration temperature) affecting the elutriation rate are also discussed in the paper.

Use of a fluidized bed for the thermal and chemicothermal treatment of metals

NASA Astrophysics Data System (ADS)

Varygin, N. N.; Ol'shanov, E. Ya.

1971-06-01

An investigation of the heat processes in a fluidized bed shows that this unit has a high heating rate and cooling rate, and allows direct control in the process of heat treatment; chemicothermal processing is speeded up 3-5 times. Examples of experimental-industrial and industrial use show the advantages of using the fluidized bed for rapid nonoxidative heating for thermal processing and pressure processing, and also for replacing expensive salt and metal baths. The use of the fluidized bed is promising for heating temperature-sensitive aluminum and other nonferrous alloys, and for heat processing refractory metals, and alloys [45], etc. It is desirable to use the fluidized bed as the cooling medium to achieve optimum cooling with reduced stresses in components of especially complex configuration. It would be promising to use the fluidized bed for carrying out chemicothermal processing and for creating new processes (including surface saturation with rare metals), especially with the application of electrical, and possibly strong magnetic, fields.

ESTIMATION OF EFFECTIVE SHEAR STRESS WORKING ON FLAT SHEET MEMBRANE USING FLUIDIZED MEDIA IN MBRs

NASA Astrophysics Data System (ADS)

Zaw, Hlwan Moe; Li, Tairi; Nagaoka, Hiroshi; Mishima, Iori

This study was aimed at estimating effective shear stress working on flat sheet membrane by the addition of fluidized media in MBRs. In both of laboratory-scale aeration tanks with and without fluidized media, shear stress variations on membrane surface and water phase velocity variations were measured and MBR operation was conducted. For the evaluation of the effective shear stress working on membrane surface to mitigate membrane surface, simulation of trans-membrane pressure increase was conducted. It was shown that the time-averaged absolute value of shear stress was smaller in the reactor with fluidized media than without fluidized media. However, due to strong turbulence in the reactor with fluidized media caused by interaction between water-phase and media and also due to the direct interaction between membrane surface and fluidized media, standard deviation of shear stress on membrane surface was larger in the reactor with fluidized media than without media. Histograms of shear stress variation data were fitted well to normal distribution curves and mean plus three times of standard deviation was defined to be a maximum shear stress value. By applying the defined maximum shear stress to a membrane fouling model, trans-membrane pressure curve in the MBR experiment was simulated well by the fouling model indicting that the maximum shear stress, not time-averaged shear stress, can be regarded as an effective shear stress to prevent membrane fouling in submerged flat-sheet MBRs.

Geology of the Selk crater region on Titan from Cassini VIMS observations

USGS Publications Warehouse

Soderblom, J.M.; Brown, R.H.; Soderblom, L.A.; Barnes, J.W.; Jaumann, R.; Le Mouélic, Stéphane; Sotin, Christophe; Stephan, K.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

2010-01-01

Observations of Titan obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) have revealed Selk crater, a geologically young, bright-rimmed, impact crater located ???800. km north-northwest of the Huygens landing site. The crater rim-crest diameter is ???90. km; its floor diameter is ???60. km. A central pit/peak, 20-30. km in diameter, is seen; the ratio of the size of this feature to the crater diameter is consistent with similarly sized craters on Ganymede and Callisto, all of which are dome craters. The VIMS data, unfortunately, are not of sufficient resolution to detect such a dome. The inner rim of Selk crater is fluted, probably by eolian erosion, while the outer flank and presumed ejecta blanket appear dissected by drainages (particularly to the east), likely the result of fluvial erosion. Terracing is observed on the northern and western walls of Selk crater within a 10-15. km wide terrace zone identified in VIMS data; the terrace zone is bright in SAR data, consistent with it being a rough surface. The terrace zone is slightly wider than those observed on Ganymede and Callisto and may reflect differences in thermal structure and/or composition of the lithosphere. The polygonal appearance of the crater likely results from two preexisting planes of weakness (oriented at azimuths of 21?? and 122?? east of north). A unit of generally bright terrain that exhibits similar infrared-color variation and contrast to Selk crater extends east-southeast from the crater several hundred kilometers. We informally refer to this terrain as the Selk "bench." Both Selk and the bench are surrounded by the infrared-dark Belet dune field. Hypotheses for the genesis of the optically bright terrain of the bench include: wind shadowing in the lee of Selk crater preventing the encroachment of dunes, impact-induced cryovolcanism, flow of a fluidized-ejecta blanket (similar to the bright crater outflows observed on Venus), and erosion of a streamlined upland formed in the lee of Selk crater by fluid flow. Vestigial circular outlines in this feature just east of Selk's ejecta blanket suggest that this might be a remnant of an ancient, cratered crust. Evidently the southern margin of the feature has sufficient relief to prevent the encroachment of dunes from the Belet dune field. We conclude that this feature either represents a relatively high-viscosity, fluidized-ejecta flow (a class intermediate to ejecta blankets and long venusian-style ejecta flows) or a streamlined upland remnant that formed downstream from the crater by erosive fluid flow from the west-northwest. ?? 2010 Elsevier Inc.

Fluidization velocity assessment of commercially available sulfur particles for use in autotrophic denitrification biofilters

USDA-ARS?s Scientific Manuscript database

There has been no evaluation of sulfur-based autotrophic denitrification using fluidized biofilters in a recirculating aquaculture system to mitigate nitrate-nitrogen loads. The objectives of this work were to quantify the particle size distribution, specific surface area, and fluidization velocitie...

21 CFR 890.5160 - Air-fluidized bed.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Air-fluidized bed. 890.5160 Section 890.5160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a...

21 CFR 890.5160 - Air-fluidized bed.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Air-fluidized bed. 890.5160 Section 890.5160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a...

21 CFR 890.5160 - Air-fluidized bed.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Air-fluidized bed. 890.5160 Section 890.5160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a...

21 CFR 890.5160 - Air-fluidized bed.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Air-fluidized bed. 890.5160 Section 890.5160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a...

21 CFR 890.5160 - Air-fluidized bed.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Air-fluidized bed. 890.5160 Section 890.5160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a...

Fluidized bed deposition of diamond

DOEpatents

Laia, Jr., Joseph R.; Carroll, David W.; Trkula, Mitchell; Anderson, Wallace E.; Valone, Steven M.

1998-01-01

A process for coating a substrate with diamond or diamond-like material including maintaining a substrate within a bed of particles capable of being fluidized, the particles having substantially uniform dimensions and the substrate characterized as having different dimensions than the bed particles, fluidizing the bed of particles, and depositing a coating of diamond or diamond-like material upon the substrate by chemical vapor deposition of a carbon-containing precursor gas mixture, the precursor gas mixture introduced into the fluidized bed under conditions resulting in excitation mechanisms sufficient to form the diamond coating.

Fluidized-Solid-Fuel Injection Process

NASA Technical Reports Server (NTRS)

Taylor, William

1992-01-01

Report proposes development of rocket engines burning small grains of solid fuel entrained in gas streams. Main technical discussion in report divided into three parts: established fluidization technology; variety of rockets and rocket engines used by nations around the world; and rocket-engine equation. Discusses significance of specific impulse and ratio between initial and final masses of rocket. Concludes by stating three important reasons to proceed with new development: proposed engines safer; fluidized-solid-fuel injection process increases variety of solid-fuel formulations used; and development of fluidized-solid-fuel injection process provides base of engineering knowledge.

Stability of fluidization

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

Gel'perin, N.I.; Ainshtein, V.G.; Nosova, V.V.

1983-01-01

The purpose of this article is to ascertain the reasons for the appearance of stagnant zones in a fluidized bed. Analyzed is the state of a hypothetical bed without the supporting gas distribution grate with fluctuations in the local velocities w of fluidizing agent in its cross sections in relation to the average value wav. It assumes that at any instant the distribution of the fluidizing agent over the bed cross section is inhomogeneous. As the local velocities and dimensions increase and the effective cross section of the grate decreases, the apparatus cross section regularly increases.

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.

Particle withdrawal from fluidized bed systems

DOEpatents

Salvador, Louis A.; Andermann, Ronald E.; Rath, Lawrence K.

1982-01-01

Method and apparatus for removing ash formed within, and accumulated at the lower portion of, a fluidized bed coal gasification reactor vessel. A supplemental fluidizing gas, at a temperature substantially less than the average fluidized bed combustion operating temperature, is injected into the vessel and upwardly through the ash so as to form a discrete thermal interface region between the fluidized bed and the ash. The elevation of the interface region, which rises with ash accumulation, is monitored by a thermocouple and interrelated with a motor controlled outlet valve. When the interface rises above the temperature indicator, the valve opens to allow removal of some of the ash, and the valve is closed, or positioned at a minimum setting, when the interface drops to an elevation below that of the thermocouple.

Model of Fluidized Bed Containing Reacting Solids and Gases

NASA Technical Reports Server (NTRS)

Bellan, Josette; Lathouwers, Danny

2003-01-01

A mathematical model has been developed for describing the thermofluid dynamics of a dense, chemically reacting mixture of solid particles and gases. As used here, "dense" signifies having a large volume fraction of particles, as for example in a bubbling fluidized bed. The model is intended especially for application to fluidized beds that contain mixtures of carrier gases, biomass undergoing pyrolysis, and sand. So far, the design of fluidized beds and other gas/solid industrial processing equipment has been based on empirical correlations derived from laboratory- and pilot-scale units. The present mathematical model is a product of continuing efforts to develop a computational capability for optimizing the designs of fluidized beds and related equipment on the basis of first principles. Such a capability could eliminate the need for expensive, time-consuming predesign testing.

Thermal and chemical remediation of mixed waste

DOEpatents

Nelson, P.A.; Swift, W.M.

1994-08-09

A process and system for treating organic waste materials without venting gaseous emissions to the atmosphere. A fluidized bed including lime particles is operated at a temperature of at least 500 C by blowing gas having 20%/70% oxygen upwardly through the bed particles at a rate sufficient to fluidize same. A toxic organic waste material is fed into the fluidized bed where the organic waste material reacts with the lime forming CaCO[sub 3]. The off gases are filtered and cooled to condense water which is separated. A portion of the calcium carbonate formed during operation of the fluidized bed is replaced with lime particles. The off gases from the fluidized bed after drying are recirculated until the toxic organic waste material in the bed is destroyed. 3 figs.

Thermal and chemical remediation of mixed waste

DOEpatents

Nelson, Paul A.; Swift, William M.

1994-01-01

A process and system for treating organic waste materials without venting gaseous emissions to the atmosphere. A fluidized bed including lime particles is operated at a temperature of at least 500.degree. C. by blowing gas having 20%/70% oxygen upwardly through the bed particles at a rate sufficient to fluidize same. A toxic organic waste material is fed into the fluidized bed where the organic waste material reacts with the lime forming CaCO.sub.3. The off gases are filtered and cooled to condense water which is separated. A portion of the calcium carbonate formed during operation of the fluidized bed is replaced with lime particles. The off gases from the fluidized bed after drying are recirculated until the toxic organic waste material in the bed is destroyed.

The Onset of Channelling in a Fluidized Mud Layer

NASA Astrophysics Data System (ADS)

Papanicolaou, T.; Tsakiris, A. G.; Billing, B. M.

2012-12-01

Fluidization of a soil occurs when the drag force exerted on the soil grains by upwelling water equals the submerged weight of the soil grains, hence reducing the effective (or contact) stress between the soil grains to zero. In nature, fluidization is commonly encountered in localized portions of highly saturated mud layers found in tidal flats, estuaries and lakes, where upward flow is initiated by significant pore water pressure gradients triggered by wave or tidal action. The water propagates through the fluidized mud layer by forming channels (or vents), carrying the fluidized mud to the surface and forming mud volcano structures. The presence of these fluidization channels alters the mud layer structure with implications on its hydraulic and geotechnical properties, such as the hydraulic conductivity. Despite the importance of these channels, the conditions that lead to their formation and their effects on the mud layer structure still remain poorly documented. The present study couples experimental and theoretical methods aimed at quantifying the conditions, under which fluidization of a saturated mud layer is accompanied by the formation of channels, and assessing the effects of channeling on the mud layer structure. Fluidization and channel formation in a mud layer were reproduced in the laboratory using a carefully designed fluidization column attached to a pressurized vessel (plenum). To eliminate any effects of the material, the mud was produced from pure kaolin clay and deionized water. Local porosity measurements along the mud layer prior, during and after fluidization were conducted using an Americium-241 gamma source placed on a fully automated carriage. Different water inflow rates, q, were applied to the base of the mud layer and the plenum pressure was monitored throughout the experiment. These experiments revealed that for high q values, a single vertical channel formed and erupted at the center of the fluidization column. Instead for low q values, the experiments suggested that a channel network formed within the mud layer leading to the eruption of multiple channels on the mud layer surface. The gamma source measurements captured quantitatively the porosity increase as the channel formed. The experiments were complemented with a theoretical analysis using the two-phase, flow mass and momentum governing equations. This analysis aims to establish a relation between the applied pressure, the fluid velocity and the local porosity of mud during the formation of the channels.

Effects of Packed Structure and Operation Conditions on Liquid Flow Behavior in Blast Furnace Hearth

NASA Astrophysics Data System (ADS)

Zuo, Haibin; Hong, Jun; Zhang, Jianliang; Zheng, Jin

The circulating flow of molten iron is an important reason that results in the erosion of blast furnace hearth. In order to prolong the campaign life of blast furnace, it is necessary to analysis the flow state of molten iron. The three-dimensional mathematical model at steady state which takes the standard k-e and porous zone model into consideration is applied to simulate the flow field under different conditions. The results showed that floating of the deadman did strengthen molten iron circulating flow. Increasing the deadman diameter will increase the erosion of hearth and bottom. Deepen the depth of the taphole and reduce the taphole diameter can reduce the circulating flow. Effect of the taphole angle from 10° to 15° is not significant. The results can be used to provide guidance for protecting the blast furnace hearth.

Research on acting mechanism and behavior of a gas bubble in the air dense medium fluidized bed

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

Tao, X.; Chen, Q.; Yang, Y.

1996-12-31

Coal dry beneficiation with air-dense medium fluidized bed has now been established as a high efficiency dry separation technology, it is the application of fluidization technology to the coal preparation field. The tiny particle media forms an uniform and stable fluidized bed with a density acted by airflow, which is used to separate 80{micro}m to {approximately}6mm size coal. This technology has achieved satisfied industrialization results, and attracted the expert`s attention in the field. In fluidized bed, the interaction between gas and solid was mainly decided by the existence state of heavy media particles mass (position and distance) relative velocity ofmore » gas-solid two phase, as well turbulent action. A change of vertical gas-solid fluidizing state essentially is the one of a energy transforming process. For a coal separating process with air-dense medium fluidized bed, the gas bubble, producing a turbulent and stirring action in the bed, leads to two effects. It can promote a uniform distribution of heavy media particles, and a uniform and stability of a bed density. Otherwise it will decrease effective contacts between gas-solids two phases, producing a bigger gas bubble. Therefore controlling a gas bubble size in bed should be optimized. This paper analyzes mutual movement between gas-solid, and studies the gas bubble behavior in the bed. A mechanic mode and a separating process of coal in the bed is discussed. It aims to research the coal separating mechanism with air-dense fluidized bed.« less

The determination of optimum condition in water hyacinth drying process by mixed adsorption drying method and modified fly ash as an adsorbent

NASA Astrophysics Data System (ADS)

Saputra, Asep Handaya; Putri, Rizky Anggreini

2017-05-01

Water hyacinth is an aquatic weed that has a very fast growth which makes it becomes a problem to the ecosystem. On the other hand, water hyacinth has a high fiber content (up to 20% by weight) which makes it potential to become raw material for composites and textile industries. As an aquatic plant, water hyacinth has a high initial moisture content that reaches more than 90%. Meanwhile the moisture content of fiber as a raw material for composite and textile industry should not be more than 10% to maintain the good quality of the products. Mixed adsorption drying method is one of the innovative method that can replace conventional drying process. Fluidization method which has been commonly used in agricultural and pharmaceutical products drying, can be enhanced by combining it with the adsorption method as performed in this study. In mixed fluidization-adsorption drying method, fly ash as adsorbent and water hyacinth fiber were put together into the fluidization column where the drying air evaporate the moisture content in water hyacinth fiber. In addition, the adsorbent adsorb the moisture content in the drying air to make the moisture content of the drying air remain low. The drying process is performed in various temperature and composition of water hyacinth and adsorbent in order to obtain the optimum drying condition. In addition, the effect of fly ash pellet and fly ash powder to the drying process was also performed. The result shows that the higher temperature and the more amount of adsorbent results in the faster drying rate. Fly ash pellet shows a better adsorption since it has a smaller pore diameter and wider surface area. The optimum temperature obtained from this study is 60°C and the optimum ratio of water hyacinth and fly ash is 50:50.

Granular compaction by fluidization

NASA Astrophysics Data System (ADS)

Tariot, Alexis; Gauthier, Georges; Gondret, Philippe

2017-06-01

How to arrange a packing of spheres is a scientific question that aroused many fundamental works since a long time from Kepler's conjecture to Edward's theory (S. F. Edwards and R.B.S Oakeshott. Theory of powders. Physica A, 157: 1080-1090, 1989), where the role traditionally played by the energy in statistical problems is replaced by the volume for athermal grains. We present experimental results on the compaction of a granular pile immersed in a viscous fluid when submited to a continuous or bursting upward flow. An initial fluidized bed leads to a well reproduced initial loose packing by the settling of grains when the high enough continuous upward flow is turned off. When the upward flow is then turned on again, we record the dynamical evolution of the bed packing. For a low enough continuous upward flow, below the critical velocity of fluidization, a slow compaction dynamics is observed. Strikingly, a slow compaction can be also observed in the case of "fluidization taps" with bursts of fluid velocity higher than the critical fluidization velocity. The different compaction dynamics is discussed when varying the different control parameters of these "fluidization taps".

Process for the production of fuel gas from coal

DOEpatents

Patel, Jitendra G.; Sandstrom, William A.; Tarman, Paul B.

1982-01-01

An improved apparatus and process for the conversion of hydrocarbonaceous materials, such as coal, to more valuable gaseous products in a fluidized bed gasification reaction and efficient withdrawal of agglomerated ash from the fluidized bed is disclosed. The improvements are obtained by introducing an oxygen containing gas into the bottom of the fluidized bed through a separate conduit positioned within the center of a nozzle adapted to agglomerate and withdraw the ash from the bottom of the fluidized bed. The conduit extends above the constricted center portion of the nozzle and preferably terminates within and does not extend from the nozzle. In addition to improving ash agglomeration and withdrawal, the present invention prevents sintering and clinkering of the ash in the fluidized bed and permits the efficient recycle of fine material recovered from the product gases by contacting the fines in the fluidized bed with the oxygen as it emanates from the conduit positioned within the withdrawal nozzle. Finally, the present method of oxygen introduction permits the efficient recycle of a portion of the product gases to the reaction zone to increase the reducing properties of the hot product gas.

Thermally activated creep and fluidization in flowing disordered materials

NASA Astrophysics Data System (ADS)

Merabia, Samy; Detcheverry, François

2016-11-01

When submitted to a constant mechanical load, many materials display power law creep followed by fluidization. A fundamental understanding of these processes is still far from being achieved. Here, we characterize creep and fluidization on the basis of a mesoscopic viscoplastic model that includes thermally activated yielding events and a broad distribution of energy barriers, which may be lowered under the effect of a local deformation. We relate the creep exponent observed before fluidization to the width of barrier distribution and to the specific form of stress redistribution following yielding events. We show that Andrade creep is accompanied by local strain hardening driven by stress redistribution and find that the fluidization time depends exponentially on the applied stress. The simulation results are interpreted in the light of a mean-field analysis, and should help in rationalizing the creep phenomenology in disordered materials.

Synchronized oscillations and acoustic fluidization in confined granular materials

NASA Astrophysics Data System (ADS)

Giacco, F.; de Arcangelis, L.; Ciamarra, M. Pica; Lippiello, E.

2018-01-01

According to the acoustic fluidization hypothesis, elastic waves at a characteristic frequency form inside seismic faults even in the absence of an external perturbation. These waves are able to generate a normal stress which contrasts the confining pressure and promotes failure. Here, we study the mechanisms responsible for this wave activation via numerical simulations of a granular fault model. We observe the particles belonging to the percolating backbone, which sustains the stress, to perform synchronized oscillations over ellipticlike trajectories in the fault plane. These oscillations occur at the characteristic frequency of acoustic fluidization. As the applied shear stress increases, these oscillations become perpendicular to the fault plane just before the system fails, opposing the confining pressure, consistently with the acoustic fluidization scenario. The same change of orientation can be induced by external perturbations at the acoustic fluidization frequency.

Method for producing and regenerating a synthetic CO.sub.2 acceptor

DOEpatents

Lancet, Michael S [Pittsburgh, PA; Curran, George P [Pittsburgh, PA; Gorin, Everett [San Rafael, CA

1982-01-01

A method for producing a synthetic CO.sub.2 acceptor by feeding a mixture of finely divided silica and at least one finely divided calcium compound selected from the group consisting of calcium oxide and calcium carbonate to a fluidized bed; operating the fluidized bed at suitable conditions to produce pellets of synthetic CO.sub.2 acceptor and recovering the pellets of synthetic CO.sub.2 acceptor from the fluidized bed. Optionally, spent synthetic CO.sub.2 acceptor can be charged to the fluidized bed to produce regenerated pellets of synthetic CO.sub.2 acceptor.

Method for producing and regenerating a synthetic CO[sub 2] acceptor

DOEpatents

Lancet, M. S.; Curran, G. P.; Gorin, E.

1982-05-18

A method is described for producing a synthetic CO[sub 2] acceptor by feeding a mixture of finely divided silica and at least one finely divided calcium compound selected from the group consisting of calcium oxide and calcium carbonate to a fluidized bed; operating the fluidized bed at suitable conditions to produce pellets of synthetic CO[sub 2] acceptor and recovering the pellets of synthetic CO[sub 2] acceptor from the fluidized bed. Optionally, spent synthetic CO[sub 2] acceptor can be charged to the fluidized bed to produce regenerated pellets of synthetic CO[sub 2] acceptor. 1 fig.

Vortex Rings Generated by a Shrouded Hartmann-Sprenger Tube

NASA Technical Reports Server (NTRS)

DeLoof, Richard L. (Technical Monitor); Wilson, Jack

2005-01-01

The pulsed flow emitted from a shrouded Hartmann-Sprenger tube was sampled with high-frequency pressure transducers and with laser particle imaging velocimetry, and found to consist of a train of vortices. Thrust and mass flow were also monitored using a thrust plate and orifice, respectively. The tube and shroud lengths were altered to give four different operating frequencies. From the data, the radius, velocity, and circulation of the vortex rings was obtained. Each frequency corresponded to a different length to diameter ratio of the pulse of air leaving the driver shroud. Two of the frequencies had length to diameter ratios below the formation number, and two above. The formation number is the value of length to diameter ratio below which the pulse converts to a vortex ring only, and above which the pulse becomes a vortex ring plus a trailing jet. A modified version of the slug model of vortex ring formation was used to compare the observations with calculated values. Because the flow exit area is an annulus, vorticity is shed at both the inner and outer edge of the jet. This results in a reduced circulation compared with the value calculated from slug theory accounting only for the outer edge. If the value of circulation obtained from laser particle imaging velocimetry is used in the slug model calculation of vortex ring velocity, the agreement is quite good. The vortex ring radius, which does not depend on the circulation, agrees well with predictions from the slug model.

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.

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

Treatment of N-Nitrosodimethylamine (NDMA) in Groundwater Using a Fluidized Bed Bioreactor

DTIC Science & Technology

2014-01-01

Nitrosodimethylamine ( NDMA ) in Groundwater Using a Fluidized Bed Bioreactor Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the...Treatment of N-Nitrosodimethylamine ( NDMA ) in Groundwater Using a Fluidized Bed Bioreactor 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...21 5.6.1 NDMA and DMN

Research and Development of Large Capacity CFB Boilers in TPRI

NASA Astrophysics Data System (ADS)

Xianbin, Sun; Minhua, Jiang

This paper presents an overview of advancements of circulating fluidized bed (CFB) technology in Thermal Power Research Institute (TPRI),including technologies and configuration and progress of scaling up. For devoloping large CFB boiler, the CFB combustion test facilities have been established, the key technologies of large capacity CFB boiler have been research systematically, the 100MW ˜330MW CFB boiler have been developed and manufactured. The first domestically designed 100MW and 210MW CFB boiler have been put into commericial operation and have good operating performance. Domestic 330MW CFB boiler demonstration project also has been put into commericial operation,which is H type CFB boiler with Compact heat exchanger. This boiler is China's largest CFB boiler. The technical plan of domestic 600MW supercritical CFB boiler are also briefly introduced.

Method and apparatus for improving heat transfer in a fluidized bed

DOEpatents

Lessor, Delbert L.; Robertus, Robert J.

1990-01-01

An apparatus contains a fluidized bed that includes particles of different triboelectrical types, each particle type acquiring an opposite polarity upon contact. The contact may occur between particles of the two types or between particles of etiher type and structure or fluid present in the apparatus. A fluidizing gas flow is passed through the particles to produce the fluidized bed. Immersed within the bed are electrodes. An alternating EMF source connected to the electrodes applies an alternating electric field across the fluidized bed to cause particles of the first type to move relative to particles of the second type and relative to the gas flow. In a heat exchanger incorporating the apparatus, the electrodes are conduits conveying a fluid to be heated. The two particle types alternately contact each conduit to transfer heat from a hot gas flow to the second fluid within the conduit.

Near-infrared spectroscopy monitoring and control of the fluidized bed granulation and coating processes-A review.

PubMed

Liu, Ronghua; Li, Lian; Yin, Wenping; Xu, Dongbo; Zang, Hengchang

2017-09-15

The fluidized bed granulation and pellets coating technologies are widely used in pharmaceutical industry, because the particles made in a fluidized bed have good flowability, compressibility, and the coating thickness of pellets are homogeneous. With the popularization of process analytical technology (PAT), real-time analysis for critical quality attributes (CQA) was getting more attention. Near-infrared (NIR) spectroscopy, as a PAT tool, could realize the real-time monitoring and control during the granulating and coating processes, which could optimize the manufacturing processes. This article reviewed the application of NIR spectroscopy in CQA (moisture content, particle size and tablet/pellet thickness) monitoring during fluidized bed granulation and coating processes. Through this review, we would like to provide references for realizing automated control and intelligent production in fluidized bed granulation and pellets coating of pharmaceutical industry. Copyright © 2017 Elsevier B.V. All rights reserved.

Turbulent dusty boundary layer in an ANFO surface-burst explosion

NASA Astrophysics Data System (ADS)

Kuhl, A. L.; Ferguson, R. E.; Chien, K. Y.; Collins, J. P.

1992-01-01

This paper describes the results of numerical simulations of the dusty, turbulent boundary layer created by a surface burst explosion. The blast wave was generated by the detonation of a 600-T hemisphere of ANFO, similar to those used in large-scale field tests. The surface was assumed to be ideally noncratering but contained an initial loose layer of dust. The dust-air mixture in this fluidized bed was modeled as a dense gas (i.e., an equilibrium model, valid for very small-diameter dust particles). The evolution of the flow was calculated by a high-order Godunov code that solves the nonsteady conservation laws. Shock interactions with dense layer generated vorticity near the wall, a result that is similar to viscous, no-slip effects found in clean flows. The resulting wall shear layer was unstable, and rolled up into large-scale rotational structures. These structures entrained dense material from the wall layer and created a chaotically striated flow. The boundary layer grew due to merging of the large-scale structures and due to local entrainment of the dense material from the fluidized bed. The chaotic flow was averaged along similarity lines (i.e., lines of constant values of x = r/Rs and y = z/Rs where R(sub s) = ct(exp alpha)) to establish the mean-flow profiles and the r.m.s. fluctuating-flow profiles of the boundary layer.

Structural Evolution of Martin Crater Thaumasia Planum, Mars

NASA Astrophysics Data System (ADS)

Dolan, Daniel J.

A detailed structural map of the central uplift of Martin Crater in western Thaumasia Planum, Mars, reveals highly folded and fractured geology throughout the 15-km diameter uplift. The stratigraphy in the central uplift of the crater has been rotated to near vertical dip and imaged by high-definition cameras aboard the Mars Reconnaissance Orbiter (MRO). These unique factors allow individual geologic beds in Martin Crater to be studied and located across the length of the uplift. Bedding in Martin Crater primarily strikes SSE-NNW and dips near vertically. Many units are separated by a highly complex series of linear faults, creating megablocks of uplifted material. Faulting is dominantly left-slip in surface expression and strikes SW-NE, roughly perpendicular to bedding, and major fold axes plunge toward the SW. Coupled with infrared imagery of the ejecta blanket, which shows an "exclusion zone" northeast of the crater, these structural indicators provide strong support for a low-angle impactor (approximately 10-20°) originating from the northeast. Acoustic fluidization is the prevailing theoretical model put forth to explain complex crater uplift. The theory predicts that uplifted megablocks in craters are small, discrete, separated and highly randomized in orientation. However, megablocks in Martin Crater are tightly interlocked and often continuous in lithology across several kilometers. Thus, the model of acoustic fluidization, as it is currently formulated, does not appear to be supported by the structural evidence found in Martin Crater.

Particulate Formation from a Copper Oxide-Based Oxygen ...

EPA Pesticide Factsheets

Attrition behavior and particle loss of a copper oxide-based oxygen carrier from a methane chemical looping combustion (CLC) process was investigated in a fluidized bed reactor. The aerodynamic diameters of most elutriated particulates, after passing through a horizontal settling duct, range between 2 and 5 μm. A notable number of submicron particulates are also identified. Oxygen carrier attrition was observed to lead to increased CuO loss resulting from the chemical looping reactions, i.e., Cu is enriched in small particles generated primarily from fragmentation in the size range of 10-75 μm. Cyclic reduction and oxidation reactions in CLC have been determined to weaken the oxygen carrier particles, resulting in increased particulate emission rates when compared to oxygen carriers without redox reactions. The generation rate for particulates < 10 μm was found to decrease with progressive cycles over as-prepared oxygen carrier particles and then reach a steady state. The surface of the oxygen carrier is also found to be coarsened due to a Kirkendall effect, which also explains the enrichment of Cu on particle surfaces and in small particles. As a result, it is important to collect and reprocess small particles generated from chemical looping processes to reduce oxygen carrier loss. The redox reactions associated with chemical looping combustion play an important role in particle attrition in the fluidized bed. Reaction-induced local stresses, due to the r

Treatment of low strength industrial cluster wastewater by anaerobic hybrid reactor.

PubMed

Kumar, Amit; Yadav, Asheesh Kumar; Sreekrishnan, T R; Satya, Santosh; Kaushik, C P

2008-05-01

The study was aimed at treating the complex, combined wastewater generated in Mangolpuri industrial cluster. It was considered as a low strength wastewater with respect to its organic content. Anaerobic treatment of this wastewater was studied using an anaerobic hybrid reactor (AHR) which combined the best features of both the upflow anaerobic sludge blanket (UASB) reactor and anaerobic fluidized bed rector (AFBR). The performance of the reactor under different organic and hydraulic loading rates were studied. The COD removal reached 94% at an organic loading rate (OLR) of 2.08 kg COD m(-3)d(-1) at an hydraulic retention time (HRT) of 6.0 h. The granules developed were characterized in terms of their diameter and terminal settling velocity.

Flying MOFs: polyamine-containing fluidized MOF/SiO 2 hybrid materials for CO 2 capture from post-combustion flue gas

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

Luz, Ignacio; Soukri, Mustapha; Lail, Marty

Solid-state synthesis ensures a high loading and well dispersed growth of a large collection of metal–organic framework (MOF) nanostructures within a series of commercially available mesoporous silica allowing to render MOFs into fluidized solid sorbents for CO 2 capture from post-combustion flue gas in a fluidized-bed reactor.

Flying MOFs: polyamine-containing fluidized MOF/SiO 2 hybrid materials for CO 2 capture from post-combustion flue gas

DOE PAGES

Luz, Ignacio; Soukri, Mustapha; Lail, Marty

2018-01-01

Solid-state synthesis ensures a high loading and well dispersed growth of a large collection of metal–organic framework (MOF) nanostructures within a series of commercially available mesoporous silica allowing to render MOFs into fluidized solid sorbents for CO 2 capture from post-combustion flue gas in a fluidized-bed reactor.

Twelfth annual fluidized bed conference

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

NONE

1996-12-31

The Proceedings of the Twelfth Annual Fluidized Bed Conference held November 11-13, 1996 in Pittsburgh, PA are presented. Information is given on: owner`s discussions; new aspects and field upgrades in fluidized bed boilers; manufacturer`s perspectives; fuel considerations; FBC ash reclassification; and beneficial uses of FBC ash. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

Combined fluidized bed retort and combustor

DOEpatents

Shang, Jer-Yu; Notestein, John E.; Mei, Joseph S.; Zeng, Li-Wen

1984-01-01

The present invention is directed to a combined fluidized bed retorting and combustion system particularly useful for extracting energy values from oil shale. The oil-shale retort and combustor are disposed side-by-side and in registry with one another through passageways in a partition therebetween. The passageways in the partition are submerged below the top of the respective fluid beds to preclude admixing or the product gases from the two chambers. The solid oil shale or bed material is transported through the chambers by inclining or slanting the fluidizing medium distributor so that the solid bed material, when fluidized, moves in the direction of the downward slope of the distributor.

Recent advances in fluidized bed drying

NASA Astrophysics Data System (ADS)

Haron, N. S.; Zakaria, J. H.; Mohideen Batcha, M. F.

2017-09-01

Fluidized bed drying are very well known to yield high heat and mass transfer and hence adopted to many industrial drying processes particularly agricultural products. In this paper, recent advances in fluidized bed drying were reviewed and focus is given to the drying related to the usage of Computational Fluid Dynamics (CFD). It can be seen that usage of modern computational tools such as CFD helps to optimize the fluidized bed dryer design and operation for lower energy consumption and thus better thermal efficiency. Among agricultural products that were reviewed in this paper were oil palm frond, wheat grains, olive pomace, coconut, pepper corn and millet.

Method for fluidizing and coating ultrafine particles, device for fluidizing and coating ultrafine particles

DOEpatents

Li, Jie; Liu, Yung Y

2015-01-20

The invention provides a method for dispersing particles within a reaction field, the method comprising confining the particles to the reaction field using a standing wave. The invention also provides a system for coating particles, the system comprising a reaction zone; a means for producing fluidized particles within the reaction zone; a fluid to produce a standing wave within the reaction zone; and a means for introducing coating moieties to the reaction zone. The invention also provides a method for coating particles, the method comprising fluidizing the particles, subjecting the particles to a standing wave; and contacting the subjected particles with a coating moiety.

[Thermal energy utilization analysis and energy conservation measures of fluidized bed dryer].

PubMed

Xing, Liming; Zhao, Zhengsheng

2012-07-01

To propose measures for enhancing thermal energy utilization by analyzing drying process and operation principle of fluidized bed dryers,in order to guide optimization and upgrade of fluidized bed drying equipment. Through a systematic analysis on drying process and operation principle of fluidized beds,the energy conservation law was adopted to calculate thermal energy of dryers. The thermal energy of fluidized bed dryers is mainly used to make up for thermal consumption of water evaporation (Qw), hot air from outlet equipment (Qe), thermal consumption for heating and drying wet materials (Qm) and heat dissipation to surroundings through hot air pipelines and cyclone separators. Effective measures and major approaches to enhance thermal energy utilization of fluidized bed dryers were to reduce exhaust gas out by the loss of heat Qe, recycle dryer export air quantity of heat, preserve heat for dry towers, hot air pipes and cyclone separators, dehumidify clean air in inlets and reasonably control drying time and air temperature. Such technical parameters such air supply rate, air inlet temperature and humidity, material temperature and outlet temperature and humidity are set and controlled to effectively save energy during the drying process and reduce the production cost.

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.

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.

Design of a Localized Fluidization Burrowing Robot

NASA Astrophysics Data System (ADS)

Dorsch, Daniel; Winter, Amos

2014-11-01

This presentation will focus on the critical fluid and granular mechanics principles that drove the design of RoboClam 2.0, a self-actuated, radially expanding underwater burrowing device. RoboClam 2.0 was inspired by the Atlantic razor clam, Ensis directus, which burrows by contracting its valves and fluidizing the surrounding soil to reduce burrowing drag. This contraction results in a localized fluidized region occurring 1-5 body radii away from the animal. Moving through a fluidized, rather than static, soil requires energy that scales linearly with depth, rather than depth squared. In addition to providing an advantage for the animal, localized fluidization may yield significant value to engineering applications such as subsea robot anchoring and pipe installation. RoboClam 2.0 is sized to be an anchoring platform for autonomous underwater vehicles. We will present the scaling relationships that can be used to design RoboClam derivatives for different size scales and applications. The critical speed, displacement and force with which the device must contract to create fluidization are calculated based on soil parameters. These parametric relationships allow for choosing actuators of appropriate size and power output for desired burrowing performance.

Vortex circulation and polarity patterns in closely packed cap arrays

DOE PAGES

Streubel, Robert; Kronast, Florian; Reiche, Christopher F.; ...

2016-01-25

For this work, we studied curvature-driven modifications to the magnetostatic coupling of vortex circulation and polarity in soft-magnetic closely packed cap arrays. A phase diagram for the magnetic remanent/transition states at room temperature as a function of diameter and thickness was assembled. For specimens with vortex remanent state (40 nm-thick Permalloy on 330 nm spherical nanoparticles), both vortex circulation and polarity were visualized. Intercap coupling upon vortex nucleation leads to the formation of vortex circulation patterns in closely packed arrays. The remanent circulation pattern can be tailored choosing the direction of the applied magnetic field with respect to the symmetrymore » axis of the hexagonal array. An even and random distribution of vortex polarity indicates the absence of any circulation-polarity coupling.« less

Layered ejecta craters and the early water/ice aquifer on Mars

NASA Astrophysics Data System (ADS)

Oberbeck, V. R.

2009-03-01

A model for emplacement of deposits of impact craters is presented that explains the size range of Martian layered ejecta craters between 5 km and 60 km in diameter in the low and middle latitudes. The impact model provides estimates of the water content of crater deposits relative to volatile content in the aquifer of Mars. These estimates together with the amount of water required to initiate fluid flow in terrestrial debris flows provide an estimate of 21% by volume (7.6 × 107 km3) of water/ice that was stored between 0.27 and 2.5 km depth in the crust of Mars during Hesperian and Amazonian time. This would have been sufficient to supply the water for an ocean in the northern lowlands of Mars. The existence of fluidized craters smaller than 5 km diameter in some places on Mars suggests that volatiles were present locally at depths less than 0.27 km. Deposits of Martian craters may be ideal sites for searches for fossils of early organisms that may have existed in the water table if life originated on Mars.

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.

The enrichment of natural radionuclides in oil shale-fired power plants in Estonia--the impact of new circulating fluidized bed technology.

PubMed

Vaasma, Taavi; Kiisk, Madis; Meriste, Tõnis; Tkaczyk, Alan Henry

2014-03-01

Burning oil shale to produce electricity has a dominant position in Estonia's energy sector. Around 90% of the overall electric energy production originates from the Narva Power Plants. The technology in use has been significantly renovated - two older types of pulverized fuel burning (PF) energy production units were replaced with new circulating fluidized bed (CFB) technology. Additional filter systems have been added to PF boilers to reduce emissions. Oil shale contains various amounts of natural radionuclides. These radionuclides concentrate and become enriched in different boiler ash fractions. More volatile isotopes will be partially emitted to the atmosphere via flue gases and fly ash. To our knowledge, there has been no previous study for CFB boiler systems on natural radionuclide enrichment and their atmospheric emissions. Ash samples were collected from Eesti Power Plant's CFB boiler. These samples were processed and analyzed with gamma spectrometry. Activity concentrations (Bq/kg) and enrichment factors were calculated for the (238)U ((238)U, (226)Ra, (210)Pb) and (232)Th ((232)Th, (228)Ra) family radionuclides and for (40)K in different CFB boiler ash fractions. Results from the CFB boiler ash sample analysis showed an increase in the activity concentrations and enrichment factors (up to 4.5) from the furnace toward the electrostatic precipitator block. The volatile radionuclide ((210)Pb and (40)K) activity concentrations in CFB boilers were evenly distributed in finer ash fractions. Activity balance calculations showed discrepancies between input (via oil shale) and output (via ash fractions) activities for some radionuclides ((238)U, (226)Ra, (210)Pb). This refers to a situation where the missing part of the activity (around 20% for these radionuclides) is emitted to the atmosphere. Also different behavior patterns were detected for the two Ra isotopes, (226)Ra and (228)Ra. A part of (226)Ra input activity, unlike (228)Ra, was undetectable in the solid ash fractions of the boiler. Most probably it is released to the surrounding environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Packed- and fluidized-bed biofilm reactor performance for anaerobic wastewater treatment.

PubMed

Denac, M; Dunn, I J

1988-07-05

Anaerobic degradation performance of a laboratory-scale packed-bed reactor (PBR) was compared with two fluidized-bed biofilm reactors (FBRs) on molasses and whey feeds. The reactors were operated under constant pH (7) and temperature (35 degrees C) conditions and were well mixed with high recirculation rates. The measured variables were chemical oxygen demand (COD), individual organic acids, gas composition, and gas rates. As carrier, sand of 0.3-0.5 mm diameter was used in the FBR, and porous clay spheres of 6 mm diameter were used in the PBR. Startup of the PBR was achieved with 1-5 day residence times. Start-up of the FBR was only successful if liquid residence times were held low at 2-3 h. COD degradations of 86% with molasses (90% was biodegradable) were reached in both the FBR and PBR at 6 h residence time and loadings of 10 g COD/L day. At higher loadings the FBR gave the best performance; even at 40-45 g COD/L day, with 6 h residence times, 70% COD was degraded. The PBR could not be operated above 20 g COD/L day without clogging. A comparison of the reaction rates show that the PBR and FBR per formed similarly at low concentrations in the reactors up to 1 g COD/L, while above 3 g COD/L the rates were 17.4 g COD/L day for the PBR and 38.4 g COD/L day for the FBR. This difference is probably due to diffusion limitations and a less active biomass content of the PBR compared with the fluidized bed.The results of dynamic step change experiments, in which residence times and feed concentrations were changed hanged at constant loading, demonstrated the rapid response of the reactors. Thus, the response times for an increase in gas rate or an increase in organic acids due to an increase in feed concentration were less than 1 day and could be explained by substrate limitation. Other slower responses were observed in which the reactor culture adapted over periods of 5-10 days; these were apparently growth related. An increase in loading of over 100% always resulted in large increases inorganic acids, especially acetic and propionic, as well as large increases in the CO(2) gas content. In general, the CO(2) content of the gas was very low, due to the large amount of dissolved CO(2) that exited with the liquid phase at low residence times. The performance of the FBR with whey was comparable to its performance with molasses, and switching of molasses to whey feed resulted in immediate good performance without adaptation.

Soil separator and sampler and method of sampling

DOEpatents

O'Brien, Barry H [Idaho Falls, ID; Ritter, Paul D [Idaho Falls, ID

2010-02-16

A soil sampler includes a fluidized bed for receiving a soil sample. The fluidized bed may be in communication with a vacuum for drawing air through the fluidized bed and suspending particulate matter of the soil sample in the air. In a method of sampling, the air may be drawn across a filter, separating the particulate matter. Optionally, a baffle or a cyclone may be included within the fluidized bed for disentrainment, or dedusting, so only the finest particulate matter, including asbestos, will be trapped on the filter. The filter may be removable, and may be tested to determine the content of asbestos and other hazardous particulate matter in the soil sample.

Size-dependent extravasation and interstitial localization of polyethyleneglycol liposomes in solid tumor-bearing mice.

PubMed

Ishida, O; Maruyama, K; Sasaki, K; Iwatsuru, M

1999-11-10

We have examined the size dependence of extravasation and interstitial localization of polyethyleneglycol-coated liposomes (PEG-liposomes) in the solid tumor tissue by means of electron microscopic observation. Liposomes composed of distearoyl phosphatidylcholine, cholesterol and distearoylphosphatidylethanolamine derivative of polyethyleneglycol (PEG) were prepared in various size ranges. PEG-liposomes with an average diameter of 100-200 nm showed the most prolonged circulation time and the greatest tumor accumulation in all the solid tumors employed in this experiment. Although large PEG-liposomes with a diameter of 400 nm showed a short circulation time in normal mice, the results in splenectomized mice indicated that they do have an intrinsic prolonged circulation character in vivo. However, large PEG-liposomes could not extravasate into solid tumor tissue. These results indicate that the size of liposomes is critical for extravasation. The electron microscopic observations revealed the almost exclusive engulfment of extravasated liposomes by tumor-associated macrophages; very few were taken up by tumor cells.

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

Streubel, Robert; Kronast, Florian; Reiche, Christopher F.

For this work, we studied curvature-driven modifications to the magnetostatic coupling of vortex circulation and polarity in soft-magnetic closely packed cap arrays. A phase diagram for the magnetic remanent/transition states at room temperature as a function of diameter and thickness was assembled. For specimens with vortex remanent state (40 nm-thick Permalloy on 330 nm spherical nanoparticles), both vortex circulation and polarity were visualized. Intercap coupling upon vortex nucleation leads to the formation of vortex circulation patterns in closely packed arrays. The remanent circulation pattern can be tailored choosing the direction of the applied magnetic field with respect to the symmetrymore » axis of the hexagonal array. An even and random distribution of vortex polarity indicates the absence of any circulation-polarity coupling.« less

Design and operation of a batch-feed fluidizing bed aerosol generator for inhalation toxicity studies

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

Shiotsuka, R.N.; Peck, R.W. Jr.; Drew, R.T.

1985-02-01

A fluidizing bed aerosol generator (FBG), designed for inhalation toxicity studies, was constructed and tested. A key design feature contributing to its operational stability was the partial masking of the screen supporting the bronze beads. This caused 20-80% of the bed to fluidize under normal operating conditions. The non-fluidizing areas functioned as reservoirs to feed the fluidizing areas. Using a bed volume of 1000 cc of bronze beads and 20 g of MnO/sub 2/ dust, the mass output rate ranged from 0.1 to 1.0 mg/min when operated at plenum pressures of 1.04 x 10/sup 2/ to 2.42 x 10/sup 2/more » kPa (minimum fluidization pressure was approximately 82.8 kPa). During daily operation at three different output rates, the FBG produced aerosols with little change in particle size distributions or concentration when operated six hours/day for five days. Furthermore, when the FBG was operated at a fixed output rate for 15 days with two recharges of MnO/sub 2/ dust, the particle size distribution did not show any cumulative increase. Thus, long-term operation of this FBG should result in a reproducible range of concentration and particle size distribution.« less

Culture of C3A cells in alginate beads for fluidized bed bioartificial liver.

PubMed

Kinasiewicz, A; Gautier, A; Lewinska, D; Bukowski, J; Legallais, C; Weryński, A

2007-11-01

Extracorporeal bioartificial liver has been designed to sustain the detoxification and synthetic function of the failed liver in patients suffering from acute liver failure until the time of liver allotransplantation or regeneration of their own. A fluidized bed, bioartificial liver improves the mass transfer velocity between the medium and the hepatocytes. Detoxification functions of the liver could be replaced by completely artificial systems, but the synthetic functions of hepatocytes may be obtained only by metabolically active cells. The aim of our study was to investigate the influence of C3A cell culture in alginate beads on synthetic function in a fluidized bed, bioartificial liver. Cells in alginate beads were prepared using an electrostatic droplet generator of our own design using low-viscosity alginate. Beads were cultured for 24 hours then 7 days in static conditions and then 24 hours of fluidization in the bioreactor to assess albumin production. We observed significantly increased albumin production by C3A cells entrapped in alginate beads during static culture. Fluidization increased albumin production compared with static culture. Fluidization performed after 7 days of static culture resulted in a significant increase in albumin synthesis. In conclusion, static culture of alginate beads hosting hepatic cells facilitates restoration of cell function.

Iron crystallization in a fluidized-bed Fenton process.

PubMed

Boonrattanakij, Nonglak; Lu, Ming-Chun; Anotai, Jin

2011-05-01

The mechanisms of iron precipitation and crystallization in a fluidized-bed reactor were investigated. Within the typical Fenton's reagent dosage and pH range, ferric ions as a product from ferrous ion oxidation would be supersaturated and would subsequently precipitate out in the form of ferric hydroxide after the initiation of the Fenton reaction. These precipitates would simultaneously crystallize onto solid particles in a fluidized-bed Fenton reactor if the precipitation proceeded toward heterogeneous nucleation. The heterogeneous crystallization rate was controlled by the fluidized material type and the aging/ripening period of the crystallites. Iron crystallization onto the construction sand was faster than onto SiO(2), although the iron removal efficiencies at 180 min, which was principally controlled by iron hydroxide solubility, were comparable. To achieve a high iron removal rate, fluidized materials have to be present at the beginning of the Fenton reaction. Organic intermediates that can form ferro-complexes, particularly volatile fatty acids, can significantly increase ferric ion solubility, hence reducing the crystallization performance. Therefore, the fluidized-bed Fenton process will achieve exceptional performance with respect to both organic pollutant removal and iron removal if it is operated with the goal of complete mineralization. Crystallized iron on the fluidized media could slightly retard the successive crystallization rate; thus, it is necessary to continuously replace a portion of the iron-coated bed with fresh media to maintain iron removal performance. The iron-coated construction sand also had a catalytic property, though was less than those of commercial goethite. Copyright © 2011 Elsevier Ltd. All rights reserved.

Fluidized-bed calciner with combustion nozzle and shroud

DOEpatents

Wielang, Joseph A.; Palmer, William B.; Kerr, William B.

1977-01-01

A nozzle employed as a burner within a fluidized bed is coaxially enclosed within a tubular shroud that extends beyond the nozzle length into the fluidized bed. The open-ended shroud portion beyond the nozzle end provides an antechamber for mixture and combustion of atomized fuel with an oxygen-containing gas. The arrangement provides improved combustion efficiency and excludes bed particles from the high-velocity, high-temperature portions of the flame to reduce particle attrition.

Fluidized bed selective pyrolysis of coal

DOEpatents

Shang, J.Y.; Cha, C.Y.; Merriam, N.W.

1992-12-15

The present invention discloses a process for the pyrolysis of coal which comprises the effective utilization of two zonal inclined fluidized beds, where said zones can be selectively controlled as to temperature and heating rate. The first zonal inclined fluidized bed serves as a dryer for crushed coal and additionally is controlled to selectively pyrolyze said coal producing substantially carbon dioxide for recycle use. The second zonal inclined fluidized bed further pyrolyses the coal to gaseous, liquid and char products under controlled temperature and heating rate zones designed to economically integrate the product mix. The gas and liquid products are recovered from the gaseous effluent stream while the char which remains can be further treated or utilized in a subsequent process step. 9 figs.

Fluidized bed selective pyrolysis of coal

DOEpatents

Shang, Jer Y.; Cha, Chang Y.; Merriam, Norman W.

1992-01-01

The present invention discloses a process for the pyrolysis of coal which comprises the effective utilization of two zonal inclined fluidized beds, where said zones can be selectively controlled as to temperature and heating rate. The first zonal inclined fluidized bed serves as a dryer for crushed coal and additionally is controlled to selectively pyrolyze said coal producing substantially carbon dioxide for recycle use. The second zonal inclined fluidized bed further pyrolyzes the coal to gaseous, liquid and char products under controlled temperature and heating rate zones designed to economically integrate the product mix. The gas and liquid products are recovered from the gaseous effluent stream while the char which remains can be further treated or utilized in a subsequent process step.

Method of and apparatus for preheating pressurized fluidized bed combustor and clean-up subsystem of a gas turbine power plant

DOEpatents

Cole, Rossa W.; Zoll, August H.

1982-01-01

In a gas turbine power plant having a pressurized fluidized bed combustor, gas turbine-air compressor subsystem and a gas clean-up subsystem interconnected for fluid flow therethrough, a pipe communicating the outlet of the compressor of the gas turbine-air compressor subsystem with the interior of the pressurized fluidized bed combustor and the gas clean-up subsystem to provide for flow of compressed air, heated by the heat of compression, therethrough. The pressurized fluidized bed combustor and gas clean-up subsystem are vented to atmosphere so that the heated compressed air flows therethrough and loses heat to the interior of those components before passing to the atmosphere.

Apparatus for hot-gas desulfurization of fuel gases

DOEpatents

Bissett, Larry A.

1992-01-01

An apparatus for removing sulfur values from a hot fuel gas stream in a fdized bed contactor containing particulate sorbent material by employing a riser tube regeneration arrangement. Sulfur-laden sorbent is continuously removed from the fluidized bed through a stand pipe to the riser tube and is rapidly regenerated in the riser tube during transport of the sorbent therethrough by employing an oxygen-containing sorbent regenerating gas stream. The riser tube extends from a location below the fluidized bed to an elevation above the fluidized bed where a gas-solid separating mechanism is utilized to separate the regenerated particulate sorbent from the regeneration gases and reaction gases so that the regenerated sorbent can be returned to the fluidized bed for reuse.

Combustion characteristics and arsenic retention during co-combustion of agricultural biomass and bituminous coal.

PubMed

Zhou, Chuncai; Liu, Guijian; Wang, Xudong; Qi, Cuicui; Hu, Yunhu

2016-08-01

A combination of thermogravimetric analysis (TG) and laboratory-scale circulated fluidized bed combustion experiment was conducted to investigate the thermochemical, kinetic and arsenic retention behavior during co-combustion bituminous coal with typical agricultural biomass. Results shown that ignition performance and thermal reactivity of coal could be enhanced by adding biomass in suitable proportion. Arsenic was enriched in fly ash and associated with fine particles during combustion of coal/biomass blends. The emission of arsenic decreased with increasing proportion of biomass in blends. The retention of arsenic may be attributed to the interaction between arsenic and fly ash components. The positive correlation between calcium content and arsenic concentration in ash suggesting that the arsenic-calcium interaction may be regarded as the primary mechanism for arsenic retention. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gas-phase and particle-phase PCDD/F congener distributions in the flue gas from an iron ore sintering plant.

PubMed

Liu, Xiaolong; Ye, Meng; Wang, Xue; Liu, Wen; Zhu, Tingyu

2017-04-01

The activated carbon injection-circulating fluidized bed (ACI-CFB)-bag filter coupling technique was studied in an iron ore sintering plant. For comparison, the removal efficiencies under the conditions without or with ACI technology were both evaluated. It was found that the polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/F) removal efficiency for total international toxic equivalence quantity (I-TEQ) concentration was improved from 91.61% to 97.36% when ACI was employed, revealing that ACI was very conducive to further controlling the PCDD/F emissions. Detailed congener distributions of PCDD/Fs in the gas-phase and particle-phase of the Inlet and Outlet samples were determined. Additionally, the PCDD/F distribution for the Fly ash-with ACI sample of was also studied. Copyright © 2016. Published by Elsevier B.V.

Experimental studies on combustion of composite biomass pellets in fluidized bed.

PubMed

Guo, Feihong; Zhong, Zhaoping

2017-12-01

This work presents studies on the combustion of Composite Biomass Pellets (CBP S ) in fluidized bed using bauxite particles as the bed material. Prior to the combustion experiment, cold-flow characterization and thermogravimetric analysis are performed to investigate the effect of air velocity and combustion mechanism of CBP S . The cold-state test shows that CBPs and bauxite particles fluidize well in the fluidized bed. However, because of the presence of large CBPs, optimization of the fluidization velocity is rather challenging. CBPs can gather at the bottom of the fluidized bed at lower gas velocities. On the contrary, when the velocity is too high, they accumulate in the upper section of the fluidized bed. The suitable fluidization velocity for the system in this study was found to be between 1.5-2.0m/s. At the same time, it is found that the critical fluidization velocity and the pressure fluctuation of the two-component system increase with the increase of CBPs mass concentration. The thermogravimetric experiment verifies that the combustion of CBPs is a first-order reaction, and it is divided into three stages: (i) dehydration, (ii) release and combustion of the volatile and (iii) the coke combustion. The combustion of CBPs is mainly based on the stage of volatile combustion, and its activation energy is greater than that of char combustion. During the combustion test, CBP S are burned at a 10kg/h feed rate, while the excess air is varied from 25% to 100%. Temperatures of the bed and flue gas concentrations (O 2 , CO, SO 2 and NO) are recorded. CBPs can be burnt stably, and the temperature of dense phase is maintained at 765-780°C. With the increase of the air velocity, the main combustion region has a tendency to move up. While the combustion is stable, O 2 and CO 2 concentrations are maintained at about 7%, and 12%, respectively. The concentration of SO 2 in the flue gas after the initial stage of combustion is nearly zero. Furthermore, NO concentration is found to be closely related to O 2 : the NO reaches its peak value after initial stage and later decreases with the continued depletion of O 2 . Towards the end of combustion, NO increases with the increase of O 2 . Copyright © 2017 Elsevier B.V. All rights reserved.

Airstream fractionation of vesicular-arbuscular mycorrhizal fungi: concentration and enumeration of propagules.

PubMed

Tommerup, I C

1982-09-01

Spores and fragments of vesicular-arbuscular mycorrhizal fungi in dry soils were concentrated up to 100-fold when the soils were partitioned by fluidization and elutriation with a series of upward airstreams at progressively increasing velocities. The propagules were transported with the finer soil particles according to their equivalent spherical diameters. The system was used to predict the transport of propagules by wind. Concentrated propagules were rapidly separated from the soil particles in each soil fraction by an aqueous flotation method. The technique is proposed as a quantitative method for estimating the numbers of spores and fragments of mycorrhizae. The scheme includes a viability test that was used to differentiate between potentially infective propagules and those that were either dormant or incapable of regrowth.

Preparation of gastro-resistant pellets containing chitosan microspheres for improvement of oral didanosine bioavailability

PubMed Central

Severino, Patrícia; de Oliveira, George G.G.; Ferraz, Humberto G.; Souto, Eliana B.; Santana, Maria H.A.

2012-01-01

The purpose of this work was to introduce a new concept of coated pellets containing chitosan microspheres loaded with didadosine for oral administration, aiming at reducing the frequency of administration and improving the bioavailability by a suitable release profile. Chitosan microspheres were produced under fluidized bed, followed by extrusion and spheronization to obtain pellets with a mean diameter of about 1 mm. The pellets were then coated with Kollidon® VA64 and Kollicoat® MAE100P in water dispersion to depict a sustained release profile. Conventional hard gelatine capsules were loaded with these pellets and tested in vitro for their release profile of didadosine. Dissolution testing confirmed that chitosan microsphere pellets provides appropriate sustained release up to 2 h behavior for didanosine. PMID:29403741

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.

Inclined fluidized bed system for drying fine coal

DOEpatents

Cha, Chang Y.; Merriam, Norman W.; Boysen, John E.

1992-02-11

Coal is processed in an inclined fluidized bed dryer operated in a plug-flow manner with zonal temperature and composition control, and an inert fluidizing gas, such as carbon dioxide or combustion gas. Recycled carbon dioxide, which is used for drying, pyrolysis, quenching, and cooling, is produced by partial decarboxylation of the coal. The coal is heated sufficiently to mobilize coal tar by further pyrolysis, which seals micropores upon quenching. Further cooling with carbon dioxide enhances stabilization.

Fluidized bed drying characteristics and modeling of ginger ( zingiber officinale) slices

NASA Astrophysics Data System (ADS)

Parlak, Nezaket

2015-08-01

In this study fluidized bed drying characteristics of ginger have been investigated. The effects of the fluidizing air temperature, velocity, humidity and bed height on the drying performance of ginger slices have been found. The experimental moisture loss data of ginger slices has been fitted to the eight thin layer drying models. Two-term model drying model has shown a better fit to the experimental data with R2 of 0.998 as compared to others.

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

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.

Fluidized coal combustion

NASA Technical Reports Server (NTRS)

Moynihan, P. I.; Young, D. L.

1979-01-01

Fluidized-bed coal combustion process, in which pulverized coal and limestone are burned in presence of forced air, may lead to efficient, reliable boilers with low sulfur dioxide and nitrogen dioxide emissions.

A new model for two-dimensional numerical simulation of pseudo-2D gas-solids fluidized beds

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

Li, Tingwen; Zhang, Yongmin

2013-10-11

Pseudo-two dimensional (pseudo-2D) fluidized beds, for which the thickness of the system is much smaller than the other two dimensions, is widely used to perform fundamental studies on bubble behavior, solids mixing, or clustering phenomenon in different gas-solids fluidization systems. The abundant data from such experimental systems are very useful for numerical model development and validation. However, it has been reported that two-dimensional (2D) computational fluid dynamic (CFD) simulations of pseudo-2D gas-solids fluidized beds usually predict poor quantitative agreement with the experimental data, especially for the solids velocity field. In this paper, a new model is proposed to improve themore » 2D numerical simulations of pseudo-2D gas-solids fluidized beds by properly accounting for the frictional effect of the front and back walls. Two previously reported pseudo-2D experimental systems were simulated with this model. Compared to the traditional 2D simulations, significant improvements in the numerical predictions have been observed and the predicted results are in better agreement with the available experimental data.« less

Staged fluidized-bed combustion and filter system

DOEpatents

Mei, Joseph S.; Halow, John S.

1994-01-01

A staged fluidized-bed combustion and filter system for substantially reducing the quantity of waste through the complete combustion into ash-type solids and gaseous products. The device has two fluidized-bed portions, the first primarily as a combustor/pyrolyzer bed, and the second as a combustor/filter bed. The two portions each have internal baffles to define stages so that material moving therein as fluidized beds travel in an extended route through those stages. Fluidization and movement is achieved by the introduction of gases into each stage through a directional nozzle. Gases produced in the combustor/pyrolyzer bed are permitted to travel into corresponding stages of the combustor/filter bed through screen filters that permit gas flow but inhibit solids flow. Any catalyst used in the combustor/filter bed is recycled. The two beds share a common wall to minimize total volume of the system. A slightly modified embodiment can be used for hot gas desulfurization and sorbent regeneration. Either side-by-side rectangular beds or concentric beds can be used. The system is particularly suited to the processing of radioactive and chemically hazardous waste.

Magnetic particle tracking for nonspherical particles in a cylindrical fluidized bed.

PubMed

Buist, Kay A; Jayaprakash, Pavithra; Kuipers, J A M; Deen, Niels G; Padding, Johan T

2017-12-01

In granular flow operations, often particles are nonspherical. This has inspired a vast amount of research in understanding the behavior of these particles. Various models are being developed to study the hydrodynamics involving nonspherical particles. Experiments however are often limited to obtain data on the translational motion only. This paper focusses on the unique capability of Magnetic Particle Tracking to track the orientation of a marker in a full 3-D cylindrical fluidized bed. Stainless steel particles with the same volume and different aspect ratios are fluidized at a range of superficial gas velocities. Spherical and rod-like particles show distinctly different fluidization behavior. Also, the distribution of angles for rod-like particles changes with position in the fluidized bed as well as with the superficial velocity. Magnetic Particle Tracking shows its unique capability to study both spatial distribution and orientation of the particles allowing more in-depth validation of Discrete Particle Models. © 2017 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers , 63: 5335-5342, 2017.

Erosional valleys in the Thaumasia region of Mars: Hydrothermal and seismic origins

USGS Publications Warehouse

Tanaka, K.L.; Dohm, J.M.; Lias, J.H.; Hare, T.M.

1998-01-01

Analysis of erosional valleys, geologic materials and features, and topography through time in the Thaumasia region of Mars using co-registered digital spatial data sets reveals significant associations that relate to valley origin. Valleys tend to originate (1) on Noachian to Early Hesperian (stages 1 and 2) large volcanoes, (2) within 50-100 km of stages 1 and 2 rift systems, and (3) within 100 km of Noachian (stage 1) impact craters >50 km in diameter. These geologic preferences explain observations of higher valley-source densities (VSDs) in areas of higher elevations and regional slopes (>1??) because the volcanoes, rifts, and craters form high, steep topography or occur in terrain of high relief. Other stage 1 and stage 2 high, steep terrains, however, do not show high VSDs. The tendency for valleys to concentrate near geologic features and the overall low drainage densities in Thaumasia compared to terrestrial surfaces rule out widespread precipitation as a major factor in valley formation (as is proposed in wann, wet climate scenarios) except perhaps during the Early Noachian, for which much of the geologic record has been obliterated. Instead, volcanoes and rifts may indicate the presence of shallow crustal intrusions that could lead to local hydrothermal circulation, melting of ground ice and snow, and groundwater sapping. However, impact-crater melt would provide a heat source at the surface that might drive away water, forming valleys in the process. Post-stage 1 craters mostly have low nearby VSDs, which, for valleys incised in older rocks, suggests burial by e??jecta and, for . younger valleys, may indicate desiccation of near-surface water and deepening of the cryosphere. Later Hesperian and Amazonian (stages 3 and 4) valleys originate within 100-200 km of three young, large impact craters and near rifts systems at Warrego Valle??s and the southern part of Coprates rise. These valleys likely developed when the cryosphere was a couple kilometers or more thick, inhibiting valley development by hydrothermal circulation. However, eruption of groundwater may have occurred from impact-induced fracturing and lateral and perhaps minor upward transport of water due to seismic pumping. The two smaller craters formed along the plateau margin where the highest potential hydraulic head would occur in aquifers beneath the plateau. In the case of the larger crater (Lowell, 200 km in diameter), potential aquifers would likely be at depths of kilometers below the cryosphere. Seismic energy generated by the Lowell impactor would have been much greater, pumping both groundwater and perhaps fluidized slurry to the surface from beneath the cryosphere to form the young valleys and flow deposit. Along the margin of Thaumasia, tectonic pressurization of groundwater also may have contributed to valley formation. Dissection of rim materials of the Argyre impact may relate to tectonic activity and the unconsolidated state of basin e??jecta.

Rotating Fluidized Bed Reactor for Space Nuclear Propulsion. Annual Report; Design Studies and Experimental Results

NASA Technical Reports Server (NTRS)

1971-01-01

The rotating fluidized bed reactor concept is being investigated for possible application in nuclear propulsion systems. Physics calculations show U-233 to be superior to U-235 as a fuel for a cavity reactor of this type. Preliminary estimates of the effect of hydrogen in the reactor, reflector material, and power peaking are given. A preliminary engineering analysis was made for U-235 and U-233 fueled systems. An evaluation of the parameters affecting the design of the system is given, along with the thrust-to-weight ratios. The experimental equipment is described, as are the special photographic techniques and procedures. Characteristics of the fluidized bed and experimental results are given, including photographic evidence of bed fluidization at high rotational velocities.

Valve for controlling solids flow

DOEpatents

Staiger, M. Daniel

1985-01-01

A valve for controlling the flow of solids comprises a vessel having an overflow point, an inlet line for discharging solids into the vessel positioned within the vessel such that the inlet line's discharge point is lower than the vessel's overflow point, and apparatus for introducing a fluidizing fluid into the vessel. The fluidizing fluid fluidizes the solids within the vessel so that they overflow at the vessel's overflow point. For the removal of nuclear waste product the vessel may be placed within a sealed container having a bottom connected transport line for transporting the solids to storage or other sites. The rate of solids flow is controlled by the flow rate of the fluidizing fluid and by V-notch weirs of different sizes spaced about the top of the vessel.

Fluidized combustion of coal. [to limit SO2 and NOx emissions

NASA Technical Reports Server (NTRS)

Pope, M.

1978-01-01

A combustion technology that permits the burning of low quality coal, and other fuels, while maintaining stack emissions within State and Federal EPA limits is discussed. Low quality fuels can be burned directly in fluidized beds while taking advantage of low furnace temperatures and chemical activity within the bed to limit SO2 and NOx emissions. The excellent heat transfer characteristics of the fluidized beds also result in a reduction of total heat transfer surface requirements. Tests on beds operating at pressures of one to ten atmospheres, at temperatures as high as 1600 F, and with gas velocities in the vicinity of four to twelve feet per second, have proven the concept. The progress that has been made in the development of fluidized bed combustion technology and work currently underway are discussed.

Valve for controlling solids flow

DOEpatents

Staiger, M.D.

1982-09-29

A valve for controlling the flow of solids comprises a vessel having an overflow point, an inlet line for discharging solids into the vessel positioned within the vessel such that the inlet line's discharge point is lower than the vessel's overflow point, and means for introducing a fluidizing fluid into the vessel. The fluidizing fluid fluidizes the solids within the vessel so that they overflow at the vessel's overflow point. For the removal of nuclear waste product the vessel may be placed within a sealed container having a bottom connected transport line for transporting the solids to storage or other sites. The rate of solids flow is controlled by the flow rate of the fluidizing fluid and by V-notch weirs of different sizes spaced about the top of the vessel.

Evaluation of microbeads of calcium alginate as a fluidized bed medium for affinity chromatography of Aspergillus niger Pectinase.

PubMed

Roy, Ipsita; Jain, Sulakshana; Teotia, Sunita; Gupta, Munishwar Nath

2004-01-01

Calcium alginate microbeads (212-425 microm) were prepared by spraying 2% (w/v) alginate solution into 1 M CaCl2 solution. The fluidization behavior of these beads was studied, and the bed expansion index and terminal velocity were found to be 4.3 and 1808 cm h(-1), respectively. Residence time distribution curves showed that the dispersion of the protein was much less with these microbeads than with conventionally prepared calcium alginate macrobeads when both kinds of beads were used for chromatography in a fluidized bed format. The fluidized bed of these beads was used for the purification of pectinase from a commercial preparation. The media performed well even with diluted feedstock; 90% activity recovery with 211-fold purification was observed.

Fluidized Crater Ejecta Deposit

NASA Technical Reports Server (NTRS)

1998-01-01

The Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) spacecraft continued to obtain high resolution images of the red planet into August 1998. At this time, each ground track (the portion of Mars available for MOC imaging on a given orbit) covers areas from about 40oN on the late afternoon side of the planet, up over the sunlit north polar cap, and down the early morning side of Mars to about 20oN latitude. Early morning and late afternoon views provide good shadowing to reveal subtle details on the martian surface. Views of Mars with such excellent lighting conditions will not be seen by MOC once MGS's Science Phasing Orbits end in mid-September 1998.

The image shown here, MOC image 47903, was targeted on Friday afternoon (PDT), August 7, 1998. This picture of ejecta from a nameless 9.1 kilometer (5.7 mile)-diameter crater was designed to take full advantage of the present lighting conditions. When the image was taken (around 5:38 p.m. (PDT) on Saturday, August 8, 1998), the Sun had just risen and was only about 6o above the eastern horizon. With the Sun so low in the local sky, the contrast between sunlit and shadowed surfaces allowed new, subtle details to be revealed on the surface of the crater ejecta deposit.

The crater shown here has ejecta of a type that was first identified in Mariner 9 and Viking Orbiter images as 'fluidized' ejecta. Ejecta is the material that is thrown out from the crater during the explosion that results when a meteor--piece of a comet or asteroid--collides with the planet. Fluidized ejecta is characterized by its lobate appearance, and sometimes by the presence of a ridge along the margin of the ejecta deposit. In the case of the crater shown here, there are two ridges that encircle the crater ejecta--this type of ejecta deposit is sometimes called a double-lobe rampart deposit. The MOC image shows that this particular crater also has 'normal' ejecta that occurs out on the plains, beyond the outermost ridge of the main, fluidized ejecta deposit.

Fluidized or 'rampart' ejecta deposits have long been thought by many Mars scientists to result from an impact into a surface that contains water. The water would have been underground, and could have been frozen or liquid. According to the prevailing model, when the meteor hit, this water was released--along with tons of rock and debris--and the ejecta flowed like mud. Images with resolutions higher than those presently attainable from the 11.6 hr elliptical orbit are needed to see the specific features (such as large boulders 'rafted' by the dense mud) that would confirm or refute this model. Such images may be acquired once MGS is in its mapping orbit.

MOC image 47903 was received and processed by the MOC team at Malin Space Science Systems on Monday afternoon (PDT), August 10, 1998. The image center is located at 27.92oN latitude and 184.66oW longitude, in the northern Tartarus Montes region.

[Magnetic field numerical calculation and analysis for magnetic coupling of centrifugal blood pump for extracorporeal circulation].

PubMed

Hu, Zhaoyan; Lu, Lijun; Zhang, Tianyi; Chen, Zhenglong; Zhang, Tao

2013-12-01

This paper mainly studies the driving system of centrifugal blood pump for extracorporeal circulation, with the core being disc magnetic coupling. Structure parameters of disc magnetic coupling are related to the ability of transferring magnetic torque. Therefore, it is necessary to carry out disc magnetic coupling permanent magnet pole number (n), air gap length (L(g)), permanent magnet thickness (L(m)), permanent magnet body inside diameter (R(i)) and outside diameter (R(o)), etc. thoroughly. This paper adopts the three-dimensional static magnetic field edge element method of Ansys for numerical calculation, and analyses the relations of magnetic coupling each parameter to transmission magnetic torque. It provides a good theory basis and calculation method for further optimization of the disc magnetic coupling.

Fluidized-Bed Cleaning of Silicon Particles

NASA Technical Reports Server (NTRS)

Rohatgi, Naresh K.; Hsu, George C.

1987-01-01

Fluidized-bed chemical cleaning process developed to remove metallic impurities from small silicon particles. Particles (250 micrometer in size) utilized as seed material in silane pyrolysis process for production of 1-mm-size silicon. Product silicon (1 mm in size) used as raw material for fabrication of solar cells and other semiconductor devices. Principal cleaning step is wash in mixture of hydrochloric and nitric acids, leaching out metals and carrying them away as soluble chlorides. Particles fluidized by cleaning solution to assure good mixing and uniform wetting.

Staged cascade fluidized bed combustor

DOEpatents

Cannon, Joseph N.; De Lucia, David E.; Jackson, William M.; Porter, James H.

1984-01-01

A fluid bed combustor comprising a plurality of fluidized bed stages interconnected by downcomers providing controlled solids transfer from stage to stage. Each stage is formed from a number of heat transfer tubes carried by a multiapertured web which passes fluidizing air to upper stages. The combustor cross section is tapered inwardly from the middle towards the top and bottom ends. Sorbent materials, as well as non-volatile solid fuels, are added to the top stages of the combustor, and volatile solid fuels are added at an intermediate stage.

Cryogenic fractionator gas as stripping gas of fines slurry in a coking and gasification process

DOEpatents

DeGeorge, Charles W.

1981-01-01

In an integrated coking and gasification process wherein a stream of fluidized solids is passed from a fluidized bed coking zone to a second fluidized bed and wherein entrained solid fines are recovered by a scrubbing process and wherein the resulting solids-liquid slurry is stripped with a stripping gas to remove acidic gases, at least a portion of the stripping gas comprises a gas comprising hydrogen, nitrogen and methane separated from the coker products.

Regeneration of lime from sulfates for fluidized-bed combustion

DOEpatents

Yang, Ralph T.; Steinberg, Meyer

1980-01-01

In a fluidized-bed combustor the evolving sulfur oxides are reacted with CaO to form calcium sulfate which is then decomposed in the presence of carbonaceous material, such as the fly ash recovered from the combustion, at temperatures of about 900.degree. to 1000.degree. C., to regenerate lime. The regenerated lime is then recycled to the fluidized bed combustor to further react with the evolving sulfur oxides. The lime regenerated in this manner is quite effective in removing the sulfur oxides.

Development of a two-fluid drag law for clustered particles using direct numerical simulation and validation through experiments

NASA Astrophysics Data System (ADS)

Abbasi Baharanchi, Ahmadreza

This dissertation focused on development and utilization of numerical and experimental approaches to improve the CFD modeling of fluidization flow of cohesive micron size particles. The specific objectives of this research were: (1) Developing a cluster prediction mechanism applicable to Two-Fluid Modeling (TFM) of gas-solid systems (2) Developing more accurate drag models for Two-Fluid Modeling (TFM) of gas-solid fluidization flow with the presence of cohesive interparticle forces (3) using the developed model to explore the improvement of accuracy of TFM in simulation of fluidization flow of cohesive powders (4) Understanding the causes and influential factor which led to improvements and quantification of improvements (5) Gathering data from a fast fluidization flow and use these data for benchmark validations. Simulation results with two developed cluster-aware drag models showed that cluster prediction could effectively influence the results in both the first and second cluster-aware models. It was proven that improvement of accuracy of TFM modeling using three versions of the first hybrid model was significant and the best improvements were obtained by using the smallest values of the switch parameter which led to capturing the smallest chances of cluster prediction. In the case of the second hybrid model, dependence of critical model parameter on only Reynolds number led to the fact that improvement of accuracy was significant only in dense section of the fluidized bed. This finding may suggest that a more sophisticated particle resolved DNS model, which can span wide range of solid volume fraction, can be used in the formulation of the cluster-aware drag model. The results of experiment suing high speed imaging indicated the presence of particle clusters in the fluidization flow of FCC inside the riser of FIU-CFB facility. In addition, pressure data was successfully captured along the fluidization column of the facility and used as benchmark validation data for the second hybrid model developed in the present dissertation. It was shown the second hybrid model could predict the pressure data in the dense section of the fluidization column with better accuracy.

A Lower Limit on the Thickness of Europa's Ice Shell from Numerical Simulations of Impact Cratering

NASA Astrophysics Data System (ADS)

Turtle, E. P.; Ivanov, B. A.

2001-12-01

If Europa has an ice-covered, liquid water ocean, the thickness of the ice shell can be tested by analyzing the impact crater morphologies revealed by Galileo images. Several of Europa's 28 primary impact structures have morphologies typical of complex impact craters on other planetary bodies: terraced rims, flat floors, and central peaks [1]. To constrain the minimum ice thickness necessary to reproduce the observed complex crater morphologies, we have performed numerical simulations, using the modified SALE-2D code [2], of the formation of impact craters in ice layers with thicknesses ranging from 5 to 11 km overlying liquid water. The target ice has ice strength properties from published laboratory data [3] with a gradual decrease towards the base of the ice as the temperature approaches the melting point. The projectile parameters were chosen to produce a 10 km diameter crater in thick ice. We find that ice layers less than 7 km thick are not sufficient to prevent an outburst of liquid water during collapse of the transient cavity. At thicknesses of 8 and 9 km we observe a boundary regime: crater collapse produces a flat or upward-domed floor, however the water under the crater center does not reach the surface. In ice greater than 10 km thick a normal transient cavity forms. These results indicate that the ice thickness, at the times and locations of complex crater formation, must have been comparable to the diameters of the transient craters, the largest of which was between 11.9 and 18.5 km [1]. Implementation of additional mechanisms such as acoustic fluidization and creep may affect the shape of the final crater produced in our simulations: acoustic fluidization can produce central peak and peak-ring craters [4], and creep may result in a flattened crater. We are currently investigating the influence of these processes on the final crater morphology. References: [1] Moore et al., Icarus 151, 2001. [2] Ivanov et al., GSA Spec. Pap., in press. [3] Beeman et al., JGR 93, 1988. [4] Melosh and Ivanov, Ann. Rev. Earth Plan. Sci. 27, 1999.

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.

Combustion characteristics of paper and sewage sludge in a pilot-scale fluidized bed.

PubMed

Yu, Yong-Ho; Chung, Jinwook

2015-01-01

This study characterizes the combustion of paper and sewage sludge in a pilot-scale fluidized bed. The highest temperature during combustion within the system was found at the surface of the fluidized bed. Paper sludge containing roughly 59.8% water was burned without auxiliary fuel, but auxiliary fuel was required to incinerate the sewage sludge, which contained about 79.3% water. The stability of operation was monitored based on the average pressure and the standard deviation of pressure fluctuations. The average pressure at the surface of the fluidized bed decreased as the sludge feed rate increased. However, the standard deviation of pressure fluctuations increased as the sludge feed rate increased. Finally, carbon monoxide (CO) emissions decreased as oxygen content increased in the flue gas, and nitrogen oxide (NOx) emissions were also tied with oxygen content.

Fluctuations, Stratification and Stability in a Liquid Fluidized Bed at Low Reynolds Number

NASA Technical Reports Server (NTRS)

Segre, P. N.; McClymer, J. P.

2004-01-01

The sedimentation dynamics of extremely low polydispersity, non-colloidal, particles are studied in a liquid fluidized bed at low Reynolds number, Re much less than 1. When fluidized, the system reaches a steady state, defined where the local average volume fraction does not vary in time. In steady state, the velocity fluctuations and the particle concentrations are found to strongly depend on height. Using our results, we test a recently developed stability model for steady state sedimentation. The model describes the data well, and shows that in steady state there is a balancing of particle fluxes due to the fluctuations and the concentration gradient. Some results are also presented for the dependence of the concentration gradient in fluidized beds on particle size; the gradients become smaller as the particles become larger and fewer in number.

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.

Computational study of heat transfer in gas fluidization

NASA Astrophysics Data System (ADS)

Hou, Q. F.; Zhou, Z. Y.; Yu, A. B.

2013-06-01

Heat transfer in gas fluidization is investigated at a particle scale by means of a combined discrete element method and computational fluid dynamicsapproach. To develop understanding of heat transfer at various conditions, the effects of a few important material properties such as particle size, the Hamaker constant and particle thermal conductivity are examined through controlled numerical experiments. It is found that the convective heat transfer is dominant, and radiative heat transfer becomes important when the temperature is high. Conductive heat transfer also plays a role depending on the flow regimes and material properties. The heat transfer between a fluidized bed and an immersed surface is enhanced by the increase of particle thermal conductivity while it is little affected by Young's modulus. The findings should be useful for better understanding and predicting the heat transfer in gas fluidization.

Advanced Magnetic Materials Methods and Numerical Models for Fluidization in Microgravity and Hypogravity

NASA Technical Reports Server (NTRS)

Atwater, James; Wheeler, Richard, Jr.; Akse, James; Jovanovic, Goran; Reed, Brian

2013-01-01

To support long-duration manned missions in space such as a permanent lunar base, Mars transit, or Mars Surface Mission, improved methods for the treatment of solid wastes, particularly methods that recover valuable resources, are needed. The ability to operate under microgravity and hypogravity conditions is essential to meet this objective. The utilization of magnetic forces to manipulate granular magnetic media has provided the means to treat solid wastes under variable gravity conditions by filtration using a consolidated magnetic media bed followed by thermal processing of the solid wastes in a fluidized bed reactor. Non-uniform magnetic fields will produce a magnetic field gradient in a bed of magnetically susceptible media toward the distributor plate of a fluidized bed reactor. A correctly oriented magnetic field gradient will generate a downward direct force on magnetic media that can substitute for gravitational force in microgravity, or which may augment low levels of gravity, such as on the Moon or Mars. This approach is termed Gradient Magnetically Assisted Fluidization (G-MAFB), in which the magnitude of the force on the fluidized media depends upon the intensity of the magnetic field (H), the intensity of the field gradient (dH/dz), and the magnetic susceptibility of the media. Fluidized beds based on the G-MAFB process can operate in any gravitational environment by tuning the magnetic field appropriately. Magnetic materials and methods have been developed that enable G-MAFB operation under variable gravity conditions.

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.

Can the collapse of a fly ash heap develop into an air-fluidized flow? - Reanalysis of the Jupille accident (1961)

NASA Astrophysics Data System (ADS)

Stilmant, Frédéric; Pirotton, Michel; Archambeau, Pierre; Erpicum, Sébastien; Dewals, Benjamin

2015-01-01

A fly ash heap collapse occurred in Jupille (Liege, Belgium) in 1961. The subsequent flow of fly ash reached a surprisingly long runout and had catastrophic consequences. Its unprecedented degree of fluidization attracted scientific attention. As drillings and direct observations revealed no water-saturated zone at the base of the deposits, scientists assumed an air-fluidization mechanism, which appeared consistent with the properties of the material. In this paper, the air-fluidization assumption is tested based on two-dimensional numerical simulations. The numerical model has been developed so as to focus on the most prominent processes governing the flow, with parameters constrained by their physical interpretation. Results are compared to accurate field observations and are presented for different stages in the model enhancement, so as to provide a base for a discussion of the relative influence of pore pressure dissipation and pore pressure generation. These results show that the apparently high diffusion coefficient that characterizes the dissipation of air pore pressures is in fact sufficiently low for an important degree of fluidization to be maintained during a flow of hundreds of meters.

Application of image processing on struvite recovery from swine wastewater by using the fluidized bed.

PubMed

Ye, Zhi-Long; Deng, Yujun; Ye, Xin; Lou, Yaoyin; Chen, Shaohua

2018-01-01

Fluidized granulation is one of the common methods used in wastewater treatment and resource recovery with harvesting millimeter-scale large particles. Presently, effective methods are lacking to measure the fluidized granules ranging from micro- to millimeter scales, with the consequence of ineffectively controlling and optimizing the granulation process. In this work, recovering struvite (MgNH 4 PO 4 ·6H 2 O) from swine wastewater by using a fluidized bed was taken as an example. Image processing was applied to analyze the properties of different types of struvite granules, including morphology, particle size distribution, number density and mass concentration. Four stages of the struvite crystal evolution were therefore defined: aggregation, aggregate compaction, cluster-agglomerating and coating growth. These stages could occur simultaneously or sequentially. Up-flow rates of 30-80 mm/s in the fluidized bed sustained 600-876 g/L granular solids. Results revealed that the coating-growth granules were formed with compact aggregates or cluster-agglomerating granules as the nuclei. The growth rates for the different types of particles, including population growth, mass increase and particle size enlargement, were determined. In final, a schematic illustration for struvite granulation process is also presented.

Fluidization of spherocylindrical particles

NASA Astrophysics Data System (ADS)

Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.

2017-06-01

Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

CFB: technology of the future?

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

Blankship, S.

2008-02-15

Fuel flexibility and a smaller carbon footprint are behind renewed interest in circulating fluidized bed (CFB) technology. The article explains the technology of CFB and discusses development of CFB units since the late 1990s. China is seeing an explosion in the number of utility-size CFBs. Alstom, Foster Wheeler, Babcock and Wilson and Alex Kvaener are today's major CFB boiler manufacturers. Alstom is testing and developing oxy-firing and post-combustion carbon capture strategies on CFB boilers. One CFB asset is its ability to burn a variety of fuels including waste coal, high sulfur coal and even discarded tires. The article mentions successfulmore » CFB projects at the Seward Station using waste coal and at the Gilbert 3 plant in the USA. Lamar is converting its Light and Power Plant from natural gas to burn coal in a 38.5 MW CFB boiler. 1 tab., 3 photos.« less

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

NONE

Circulating fluidized-bed (CFB) boilers have ben used for years in Scandinavia to burn refuse-derived fuel (RDF). Now, Foster Wheeler Power Systems, Inc., (Clinton, N.J.) is bringing the technology to the US. Touted as the world`s largest waste-to-energy plant to use CFB technology, the Robbins (III.) Resource Recovery Facility will have the capacity to process 1,600 tons/d of municipal solid waste (MSW) when it begins operation in early 1997. The facility will have two materials-separation and RDF-processing trains, each with dual trommel screens, magnetic and eddy current separators, and shredders. About 25% of the incoming MSW will be sorted and removedmore » for recycling, while 75% of it will be turned into fuel, with a heat value of roughly 6,170 btu/lb. Once burned in the twin CFB boilers the resulting steam will be routed through a single turbine generator to produce 50,000 mW of electric power.« 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.

Fluidized bed combustor 50 MW thermal power plant, Krabi, Thailand. Feasibility study. Export trade information

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

Not Available

The report presents the results of a study prepared by Burns and Roe for the Electricity Generating Authority of Thailand to examine the technical feasibility and economic attractiveness for building a 50 MW Atmospheric Fluidized Bed Combustion lignite fired power plant at Krabi, southern Thailand. The study is divided into seven main sections, plus an executive summary and appendices: (1) Introduction; (2) Atmospheric Fluidized Bed Combustion Technology Overview; (3) Fuel and Limestone Tests; (4) Site Evaluation; (5) Station Design and Arrangements; (6) Environmental Considerations; (7) Economic Analysis.

Phase holdups in three-phase fluidized beds in the presence of disc promoter

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

Murty, M.S.N.; Ramesh, K.V.; Venkateswarlu, P.

2011-02-15

Three-phase fluidized beds are found to have wide applications in process industries. The present investigation essentially comprises of the studies on gas holdup, liquid holdup and bed porosity in three-phase fluidized beds with coaxially placed disc promoter. Holdup data were obtained from bed expansion and pressure drop measurements. Analysis of the data was done to elucidate the effects of dynamic and geometric parameters on gas holdup, liquid holdup and bed porosity. Data were correlated and useful equations were obtained from empirical modeling. (author)

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.

Characterization of solid fuels at pressurized fluidized bed gasification conditions

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

Zevenhoven, R.; Hupa, M.

1998-07-01

The gasification of co-gasification of solid fuel (coal, peat, wood) in air-blown fluidized bed gasifiers is receiving continued attention as an alternative to entrained flow gasifiers which in general are oxygen-blown. Fluidized bed gasification of wood and wood-waste at elevated pressures, and the so-called air-blown gasification cycle are examples of processes which are under development in Europe. based on complete or partial gasification of a solid fuel in a pressurized fluidized bed. At the same time, fuel characterization data for the combination of temperature, pressure and fuel particle heating rate that is encountered in fluidized bed gasification are very scarce.more » In this paper, quantitative data on the characterization of fuels for advanced combustion and gasification technologies based on fluidized beds are given, as a result from the authors participation in the JOULE 2 extension project on clean coal technology of the European community. Eleven solid fuels, ranging from coal via peat to wood, have been studied under typical fluidized bed gasification conditions: 800--1,000 C, 1--25 bar, fuel heating rate in the order of 100--1,000 C/s. Carbon dioxide was used as gasifying agent. A pressurized thermogravimetric reactor was used for the experiments. The results show that the solid residue yield after pyrolysis/devolatilization increases with pressure and decreases with temperature. For coal, the gasification reactivity of the char increases by a factor of 3 to 4 when pressurizing from 1 to 25 bar, for the younger fuels such as peat and wood, this effect is negligible. Several empirical engineering equations are given which relate the fuel performance to the process parameters and the proximate and chemical analyses of the fuel. A pressure maximum was found at which a maximum gasification reactivity occurs, for practically all fuels, and depending on temperature. It is shown that this can be explained and modeled using a Langmuir-Hinshelwood model.« less

Lipid encapsulated phenolic compounds by fluidization

USDA-ARS?s Scientific Manuscript database

Phenolic compounds exhibit antioxidant and antimicrobial activities with applications as functional food and feed additives. Ferulic acid, a phenolic compound present in grain crops and lignocellulose biomass, was encapsulated with saturated triglycerides using a laboratory fluidizer. Stability of t...

Metal wastage design guidelines for bubbling fluidized-bed combustors. Final report

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

Lyczkowski, R.W.; Podolski, W.F.; Bouillard, J.X.

These metal wastage design guidelines identify relationships between metal wastage and (1) design parameters (such as tube size, tube spacing and pitch, tube bundle and fluidized-bed height to distributor, and heat exchanger tube material properties) and (2) operating parameters (such as fluidizing velocity, particle size, particle hardness, and angularity). The guidelines are of both a quantitative and qualitative nature. Simplified mechanistic models are described, which account for the essential hydrodynamics and metal wastage processes occurring in bubbling fluidized beds. The empirical correlational approach complements the use of these models in the development of these design guidelines. Data used for modelmore » and guideline validation are summarized and referenced. Sample calculations and recommended design procedures are included. The influences of dependent variables on metal wastage, such as solids velocity, bubble size, and in-bed pressure fluctuations, are discussed.« less

A 2.5D Computational Method to Simulate Cylindrical Fluidized Beds

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

Li, Tingwen; Benyahia, Sofiane; Dietiker, Jeff

2015-02-17

In this paper, the limitations of axisymmetric and Cartesian two-dimensional (2D) simulations of cylindrical gas-solid fluidized beds are discussed. A new method has been proposed to carry out pseudo-two-dimensional (2.5D) simulations of a cylindrical fluidized bed by appropriately combining computational domains of Cartesian 2D and axisymmetric simulations. The proposed method was implemented in the open-source code MFIX and applied to the simulation of a lab-scale bubbling fluidized bed with necessary sensitivity study. After a careful grid study to ensure the numerical results are grid independent, detailed comparisons of the flow hydrodynamics were presented against axisymmetric and Cartesian 2D simulations. Furthermore,more » the 2.5D simulation results have been compared to the three-dimensional (3D) simulation for evaluation. This new approach yields better agreement with the 3D simulation results than with axisymmetric and Cartesian 2D simulations.« less

Operation of magnetically assisted fluidized beds in microgravity and variable gravity: experiment and theory

NASA Technical Reports Server (NTRS)

Sornchamni, T.; Jovanovic, G. N.; Reed, B. P.; Atwater, J. E.; Akse, J. R.; Wheeler, R. R.

2004-01-01

The conversion of solid waste into useful resources in support of long duration manned missions in space presents serious technological challenges. Several technologies, including supercritical water oxidation, microwave powered combustion and fluidized bed incineration, have been tested for the conversion of solid waste. However, none of these technologies are compatible with microgravity or hypogravity operating conditions. In this paper, we present the gradient magnetically assisted fluidized bed (G-MAFB) as a promising operating platform for fluidized bed operations in the space environment. Our experimental and theoretical work has resulted in both the development of a theoretical model based on fundamental principles for the design of the G-MAFB, and also the practical implementation of the G-MAFB in the filtration and destruction of solid biomass waste particles from liquid streams. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Bio-oil production from fast pyrolysis of waste furniture sawdust in a fluidized bed.

PubMed

Heo, Hyeon Su; Park, Hyun Ju; Park, Young-Kwon; Ryu, Changkook; Suh, Dong Jin; Suh, Young-Woong; Yim, Jin-Heong; Kim, Seung-Soo

2010-01-01

The amount of waste furniture generated in Korea was over 2.4 million tons in the past 3 years, which can be used for renewable energy or fuel feedstock production. Fast pyrolysis is available for thermo-chemical conversion of the waste wood mostly into bio-oil. In this work, fast pyrolysis of waste furniture sawdust was investigated under various reaction conditions (pyrolysis temperature, particle size, feed rate and flow rate of fluidizing medium) in a fluidized-bed reactor. The optimal pyrolysis temperature for increased yields of bio-oil was 450 degrees C. Excessively smaller or larger feed size negatively affected the production of bio-oil. Higher flow and feeding rates were more effective for the production of bio-oil, but did not greatly affect the bio-oil yields within the tested ranges. The use of product gas as the fluidizing medium had a potential for increased bio-oil yields.

A fluidized bed membrane bioelectrochemical reactor for energy-efficient wastewater treatment.

PubMed

Li, Jian; Ge, Zheng; He, Zhen

2014-09-01

A fluidized bed membrane bioelectrochemical reactor (MBER) was investigated using fluidized granular activated carbon (GAC) as a mean of membrane fouling control. During the 150-day operation, the MBER generated electricity with contaminant removal from either synthetic solution or actual wastewater, as a standalone or a coupled system. It was found that fluidized GAC could significantly reduce transmembrane pressure (TMP), although its function as a part of the anode electrode was minor. When the MBER was linked to a regular microbial fuel cell (MFC) for treating a wastewater from a cheese factory, the MFC acted as a major process for energy recovery and contaminant removal, and the coupled system removed more than 90% of chemical oxygen demand and >80% of suspended solids. The analysis showed that the ratio of energy recovery and consumption was slightly larger than one, indicating that the coupled system could be theoretically energy neutral. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison of attrition test methods: ASTM standard fluidized bed vs jet cup

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

Zhao, R.; Goodwin, J.G. Jr.; Jothimurugesan, K.

2000-05-01

Attrition resistance is one of the key design parameters for catalysts used in fluidized-bed and slurry phase types of reactors. The ASTM fluidized-bed test has been one of the most commonly used attrition resistance evaluation methods; however, it requires the use of 50 g samples--a large amount for catalyst development studies. Recently a test using the jet cup requiring only 5 g samples has been proposed. In the present study, two series of spray-dried iron catalysts were evaluated using both the ASTM fluidized-bed test and a test based on the jet cup to determine this comparability. It is shown thatmore » the two tests give comparable results. This paper, by reporting a comparison of the jet-cup test with the ASTM standard, provides a basis for utilizing the more efficient jet cup with confidence in catalyst attrition studies.« less

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.

Design and evaluation of fluidized bed heat recovery for diesel engine systems

NASA Technical Reports Server (NTRS)

Hamm, J. R.; Newby, R. A.; Vidt, E. J.; Lippert, T. E.

1985-01-01

The potential of utilizing fluidized bed heat exchangers in place of conventional counter-flow heat exchangers for heat recovery from adiabatic diesel engine exhaust gas streams was studied. Fluidized bed heat recovery systems were evaluated in three different heavy duty transport applications: (1) heavy duty diesel truck; (2) diesel locomotives; and (3) diesel marine pushboat. The three applications are characterized by differences in overall power output and annual utilization. For each application, the exhaust gas source is a turbocharged-adiabatic diesel core. Representative subposed exhaust gas heat utilization power cycles were selected for conceptual design efforts including design layouts and performance estimates for the fluidized bed heat recovery heat exchangers. The selected power cycles were: organic rankine with RC-1 working fluid, turbocompound power turbine with steam injection, and stirling engine. Fuel economy improvement predictions are used in conjunction with capital cost estimates and fuel price data to determine payback times for the various cases.

The preparation of calcium superoxide in a flowing gas stream and fluidized bed

NASA Technical Reports Server (NTRS)

Wood, P. C.; Ballou, E. V.; Spitze, L. A.; Wydeven, T.

1980-01-01

Superoxides can be used as sources of chemically stored oxygen in emergency breathing apparatus. The work reported here describes the use of a low-pressure nitrogen gas sweep through the reactant bed, for temperature control and water vapor removal. For a given set of gas temperature, bed thickness, and reaction time values, the highest purity calcium superoxide, Ca(O2)2, was obtained at the highest space velocity of the nitrogen gas sweep. The purity of the product was further increased by flow conditions that resulted in the fluidization of the reactant bed. However, scale-up of the low-pressure fluidized bed process was limited to the formation of agglomerates of reactant particles, which hindered thermal control by the flowing gas stream. A radiofrequency flow discharge inside the reaction chamber prevented agglomeration, presumably by dissipation of the static charges on the fluidized particles.

Emission characteristics for gaseous- and size-segregated particulate PAHs in coal combustion flue gas from circulating fluidized bed (CFB) boiler.

PubMed

Wang, Ruwei; Liu, Guijian; Sun, Ruoyu; Yousaf, Balal; Wang, Jizhong; Liu, Rongqiong; Zhang, Hong

2018-07-01

The partitioning behavior of polycyclic aromatic hydrocarbons (PAHs) between gaseous and particulate phases from coal-fired power plants (CFPPs) is critically important to predict PAH removal by dust control devices. In this study, 16 US-EPA priority PAHs in gaseous and size-segregated particulate phases at the inlet and outlet of the fabric filter unit (FFs) of a circulating fluidized bed (CFB) boiler were analyzed. The partitioning mechanisms of PAHs between gaseous and particulate phases and in particles of different size classes were investigated. We found that the removal efficiencies of PAHs are 45.59% and 70.67-89.06% for gaseous and particulate phases, respectively. The gaseous phase mainly contains low molecular weight (LMW) PAHs (2- and 3-ring PAHs), which is quite different from the particulate phase that mainly contains medium and high molecular weight (MMW and HMW) PAHs (4- to 6-ring PAHs). The fractions of LMW PAHs show a declining trend with the decrease of particle size. The gas-particle partitioning of PAHs is primarily controlled by organic carbon absorption, in addition, it has a clear dependence on the particle sizes. Plot of log (TPAH/PM) against logD p shows that all slope values were below -1, suggesting that PAHs were mainly adsorbed to particulates. The adsorption effect of PAHs in size-segregated PMs for HMW PAHs is more evident than LMW PAHs. The particle size distributions (PSDs) of individual PAHs show that most of PAHs exhibit bi-model structures, with one mode peaking in the accumulation size range (2.1-1.1 μm) and another mode peaking in coarse size range (5.8-4.7 μm). The intensities of these two peaks vary in function of ring number of PAHs, which is likely attributed to Kelvin effect that the less volatile HMW PAH species preferentially condense onto the finer particulates. The emission factor of PAHs was calculated as 3.53 mg/kg of coal burned, with overall mean EF PAH of 0.55 and 2.98 mg/kg for gaseous and particulate phase, respectively. Moreover, the average emission amount of PAHs for the investigated CFPP was 1016.6 g/day and 371073.6 g/y, respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Martian impact crater ejecta morphologies and their potential as indicators of subsurface volatile distribution

NASA Technical Reports Server (NTRS)

Barlow, Nadine G.

1991-01-01

Many martian impact craters ejecta morphologies suggestive of fluidization during ejecta emplacement. Impact into subsurface volatile reserviors (i.e., water, ice, CO2, etc.) is the mechanism favored by many scientists, although acceptance of this mechanism is not unanimous. In recent years, a number of studies were undertaken to better understand possible relationships between ejecta morphology and latitude, longitude, crater diameter, and terrain. These results suggest that subsurface volatiles do influence the formation of specific ejecta morphologies and may provide clues to the vertical and horizontal distribution of volatiles in more localized regions of Mars. The location of these volatile reservoirs will be important to humans exploring and settling Mars in the future. Qualitative descriptions of ejecta morphology and quantitative analyses of ejecta sinuosity and ejecta lobe areal extent from the basis of the studies. Ejecta morphology studies indicate that morphology is correlated with crater diameter and latitude, and, using depth-diameter relationships, these correlations strongly suggest that changes in morphology are related to transition among subsurface layers with varying amounts of volatiles. Ejecta sinuosity studies reveal correlations between degree of sinuosity (lobateness) and crater morphology, diameter, latitude, and terrain. Lobateness, together with variations in areal extent of the lobate ejecta blanket with morphology and latitude, probably depends most directly on the ejecta emplacement process. The physical parameters measured here can be compared with those predicted by existing ejecta emplacement models. Some of these parameters are best reproduced by models requiring incorporation of volatiles within the ejecta. However, inconsistencies between other parameters and the models indicate that more detailed modeling is necessary before the location of volatile reservoirs can be confidently predicted based on ejecta morphology studies alone.

Integration of stripping of fines slurry in a coking and gasification process

DOEpatents

DeGeorge, Charles W.

1980-01-01

In an integrated fluid coking and gasification process wherein a stream of fluidized solids is passed from a fluidized bed coking zone to a second fluidized bed and wherein entrained solid fines are recovered by a wet scrubbing process and wherein the resulting solids-liquid slurry is stripped to remove acidic gases, the stripped vapors of the stripping zone are sent to the gas cleanup stage of the gasification product gas. The improved stripping integration is particularly useful in the combination coal liquefaction process, fluid coking of bottoms of the coal liquefaction zone and gasification of the product coke.

Fluidized-bed catalytic coal-gasification process. [US patent; pretreatment to minimize agglomeration

DOEpatents

Euker, C.A. Jr.; Wesselhoft, R.D.; Dunkleman, J.J.; Aquino, D.C.; Gouker, T.R.

1981-09-14

Coal or similar carbonaceous solids impregnated with gasification catalyst constituents are oxidized by contact with a gas containing between 2 vol % and 21 vol % oxygen at a temperature between 50 and 250/sup 0/C in an oxidation zone and the resultant oxidized, catalyst impregnated solids are then gasified in a fluidized bed gasification zone at an elevated pressure. The oxidation of the catalyst impregnated solids under these conditions insures that the bed density in the fluidized bed gasification zone will be relatively high even though the solids are gasified at elevated pressure and temperature.

TREATMENT OF MUNICIPAL WASTEWATERS BY THE FLUIDIZED BED BIOREACTOR PROCESS

EPA Science Inventory

A 2-year, large-scale pilot investigation was conducted at the City of Newburgh Water Pollution Control Plant, Newburgh, NY, to demonstrate the application of the fluidized bed bioreactor process to the treatment of municipal wastewaters. The experimental effort investigated the ...

Low temperature fluidized wood chip drying with monoterpene analysis

Treesearch

Bridget N. Bero; Alarick Reiboldt; Ward Davis; Natalie Bedard; Evan Russell

2011-01-01

This paper describes the drying of ponderosa pine wood chips at low (20°C and 50°C) temperatures using a bench-scale batch pulsed fluidizer to evaluate both volatile pine oils (monoterpenes) and moisture losses during drying.

Three-axis acoustic device for levitation of droplets in an open gas stream and its application to examine sulfur dioxide absorption by water droplets.

PubMed

Stephens, Terrance L; Budwig, Ralph S

2007-01-01

Two acoustic devices to stabilize a droplet in an open gas stream (single-axis and three-axis levitators) have been designed and tested. The gas stream was provided by a jet apparatus with a 64 mm exit diameter and a uniform velocity profile. The acoustic source used was a Langevin vibrator with a concave reflector. The single-axis levitator relied primarily on the radial force from the acoustic field and was shown to be limited because of significant droplet wandering. The three-axis levitator relied on a combination of the axial and radial forces. The three-axis levitator was applied to examine droplet deformation and circulation and to investigate the uptake of SO(2) from the gas stream to the droplet. Droplets ranging in diameters from 2 to 5 mm were levitated in gas streams with velocities up to 9 ms. Droplet wandering was on the order of a half droplet diameter for a 3 mm diameter droplet. Droplet circulation ranged from the predicted Hadamard-Rybczynski pattern to a rotating droplet pattern. Droplet pH over a central volume of the droplet was measured by planar laser induced fluorescence. The results for the decay of droplet pH versus time are in general agreement with published theory and experiments.

Three-axis acoustic device for levitation of droplets in an open gas stream and its application to examine sulfur dioxide absorption by water droplets

NASA Astrophysics Data System (ADS)

Stephens, Terrance L.; Budwig, Ralph S.

2007-01-01

Two acoustic devices to stabilize a droplet in an open gas stream (single-axis and three-axis levitators) have been designed and tested. The gas stream was provided by a jet apparatus with a 64mm exit diameter and a uniform velocity profile. The acoustic source used was a Langevin vibrator with a concave reflector. The single-axis levitator relied primarily on the radial force from the acoustic field and was shown to be limited because of significant droplet wandering. The three-axis levitator relied on a combination of the axial and radial forces. The three-axis levitator was applied to examine droplet deformation and circulation and to investigate the uptake of SO2 from the gas stream to the droplet. Droplets ranging in diameters from 2to5mm were levitated in gas streams with velocities up to 9m /s. Droplet wandering was on the order of a half droplet diameter for a 3mm diameter droplet. Droplet circulation ranged from the predicted Hadamard-Rybczynski pattern to a rotating droplet pattern. Droplet pH over a central volume of the droplet was measured by planar laser induced fluorescence. The results for the decay of droplet pH versus time are in general agreement with published theory and experiments.

Mid-section of a can-annular gas turbine engine with a cooling system for the transition

DOEpatents

Wiebe, David J.; Rodriguez, Jose L.

2015-12-08

A cooling system is provided for a transition (420) of a gas turbine engine (410). The cooling system includes a cowling (460) configured to receive an air flow (111) from an outlet of a compressor section of the gas turbine engine (410). The cowling (460) is positioned adjacent to a region of the transition (420) to cool the transition region upon circulation of the air flow within the cowling (460). The cooling system further includes a manifold (121) to directly couple the air flow (111) from the compressor section outlet to an inlet (462) of the cowling (460). The cowling (460) is configured to circulate the air flow (111) within an interior space (426) of the cowling (460) that extends radially outward from an inner diameter (423) of the cowling to an outer diameter (424) of the cowling at an outer surface.

Analysis of the release process of phenylpropanolamine hydrochloride from ethylcellulose matrix granules V. Release properties of ethylcellulose layered matrix granules.

PubMed

Fukui, Atsuko; Fujii, Ryuta; Yonezawa, Yorinobu; Sunada, Hisakazu

2008-04-01

In the pharmaceutical preparation of a controlled release drug, it is very important and necessary to understand the release properties. In previous papers, a combination of the square-root time law and cube-root law equations was confirmed to be a useful equation for qualitative treatment. It was also confirmed that the combination equation could analyze the release properties of layered granules as well as matrix granules. The drug release property from layered granules is different from that of matrix granules. A time lag occurs before release, and the entire release property of layered granules was analyzed using the combination of the square-root time law and cube-root law equations. It is considered that the analysis method is very useful and efficient for both matrix and layered granules. Comparing the granulation methods, it is easier to control the manufacturing process by tumbling granulation (method B) than by tumbling-fluidized bed granulation (method C). Ethylcellulose (EC) layered granulation by a fluidized bed granulator might be convenient for the preparation of controlled release dosage forms as compared with a tumbling granulator, because the layered granules prepared by the fluidized bed granulator can granulate and dry at the same time. The time required for drying by the fluidized bed granulator is shorter than that by the tumbling granulator, so the fluidized bed granulator is convenient for preparation of granules in handling and shorter processing time than the tumbling granulator. It was also suggested that the EC layered granules prepared by the fluidized bed granulator were suitable for a controlled release system as well as the EC matrix granules.

Lateral solids dispersion coefficient in large-scale fluidized beds

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

Liu, Daoyin; Chen, Xiaoping

2010-11-15

The design of fuel feed ports in a large-scale fluidized bed combustor depends on the fuel characteristics and lateral solids mixing. However, the reported values of the effective lateral solids dispersion coefficient (D{sub sr}) are scattered in the broad range of 0.0001-0.1 m{sup 2}/s. With the aim of predicting D{sub sr} in wider fluidized beds which is difficult to measure directly or deduce from experimental results in lab-scale facilities, a computational method is proposed. It combines the Eulerian-Granular simulation and fictitious particle tracing technique. The value of D{sub sr} is calculated based on the movement of the tracers. The effectmore » on D{sub sr} of bed width (W) ranging from 0.4 m up to 12.8 m at different levels of superficial gas velocity (U{sub 0}) is investigated. It is found that increasing W whilst maintaining U{sub 0}, D{sub sr} initially increases markedly, then its increase rate declines, and finally it stays around a constant value. The computed values of D{sub sr} are examined quantitatively and compared with a thorough list of the measured D{sub sr} in the literature since 1980s. Agreed with the measurements performed in the pilot-scale fluidized beds, the value of D{sub sr} in wider facilities at higher fluidizing velocities is predicted to be around the order of magnitude of 0.1 m{sup 2}/s, much higher than that in lab-scale beds. Finally, the effect of D{sub sr} on the distribution of fuel particles over the cross section in fluidized beds with the specified layout of feed ports is discussed. (author)« less

Alternating Field Electronanofluidization

NASA Astrophysics Data System (ADS)

Espin, M. J.; Valverde, J. M.; Quintanilla, M. A. S.; Castellanos, A.

2009-06-01

The use of fluidized beds to remove submicron particles from gases has been investigated since 1949. High efficiency removal was achieved in the 1970's by imposing an electric field on a fluidized bed of semi-insulating granules that were able to collect the charged pollutant entrained in the fluidizing gas. In spite of their extended use nowadays, the collection efficiency of electrofluidized beds (EFB) is still hindered by gas bypassing associated to gas bubbling and the consequent requirement of too high gas flow and pressure drop. In this paper we report on the electromechanical behavior of an EFB of insulating nanoparticles. When fluidized by gas, these nanoparticles form extremely porous light agglomerates of size of the order of hundreds of microns that allow for a highly expanded nonbubbling fluidized state at reduced gas flow. It is found that fluidization uniformity and bed expansion are additionally enhanced by an imposed AC electric field for field oscillation frequencies of several tens of hertzs and field strengths of the order of 1 kV/cm. For oscillation frequencies of the order of hertzs, or smaller, bed expansion is hindered due to electrophoretic deposition of the agglomerates onto the vessel walls, whereas for oscillation frequencies of the order of kilohertzs, or larger, electrophoresis is nullified and bed expansion is not affected. According to a proposed model, the size of nanoparticle agglomerates stems from the balance between shear, which depends on field strength, and van der Waals forces. The optimum field strength for enhancing bed expansion produces an electric force on the agglomerates similar to their weight force, while the oscillation velocity of the agglomerates is similar to the gas velocity.

A New Fluidized Bed Bioreactor Based on Diversion-Type Microcapsule Suspension for Bioartificial Liver Systems

PubMed Central

Li, Jianzhou; Yu, Liang; Chen, Ermei; Zhu, Danhua; Zhang, Yimin; Li, LanJuan

2016-01-01

A fluidized bed bioreactor containing encapsulated hepatocytes may be a valuable alternative to a hollow fiber bioreactor for achieving the improved mass transfer and scale-up potential necessary for clinical use. However, a conventional fluidized bed bioreactor (FBB) operating under high perfusion velocity is incapable of providing the desired performance due to the resulting damage to cell-containing microcapsules and large void volume. In this study, we developed a novel diversion-type microcapsule-suspension fluidized bed bioreactor (DMFBB). The void volume in the bioreactor and stability of alginate/chitosan microcapsules were investigated under different flow rates. Cell viability, synthesis and metabolism functions, and expression of metabolizing enzymes at transcriptional levels in an encapsulated hepatocyte line (C3A cells) were determined. The void volume was significantly less in the novel bioreactor than in the conventional FBB. In addition, the microcapsules were less damaged in the DMFBB during the fluidization process as reflected by the results for microcapsule retention rates, swelling, and breakage. Encapsulated C3A cells exhibited greater viability and CYP1A2 and CYP3A4 activity in the DMFBB than in the FBB, although the increases in albumin and urea synthesis were less prominent. The transcription levels of several CYP450-related genes and an albumin-related gene were dramatically greater in cells in the DMFBB than in those in the FBB. Taken together, our results suggest that the DMFBB is a promising alternative for the design of a bioartificial liver system based on a fluidized bed bioreactor with encapsulated hepatocytes for treating patients with acute hepatic failure or other severe liver diseases. PMID:26840840

The simulation and experimental validation on gas-solid two phase flow in the riser of a dense fluidized bed

NASA Astrophysics Data System (ADS)

Wang, Xue-Yao; Jiang, Fan; Xu, Xiang; Wang, Sheng-Dian; Fan, Bao-Guo; Xiao, Yun-Han

2009-06-01

Gas-solid flow in dense CFB (circulating fluidized bed)) riser under the operating condition, superficial gas 15.5 m/s and solid flux 140 kg/m2s using Geldart B particles (sand) was investigated by experiments and CFD (computational fluid dynamics) simulation. The overall and local flow characteristics are determined using the axial pressure profiles and solid concentration profiles. The cold experimental results indicate that the axial solid concentration distribution contains a dilute region towards the up-middle zone and a dense region near the bottom and the top exit zones. The typical core-annulus structure and the back-mixing phenomenon near the wall of the riser can be observed. In addition, owing to the key role of the drag force of gas-solid phase, a revised drag force coefficient, based on the EMMS (energy-minimization multi-scale) model which can depict the heterogeneous character of gas-solid two phase flow, was proposed and coupled into the CFD control equations. In order to find an appropriate drag force model for the simulation of dense CFB riser, not only the revised drag force model but some other kinds of drag force model were used in the CFD. The flow structure, solid concentration, clusters phenomenon, fluctuation of two phases and axial pressure drop were analyzed. By comparing the experiment with the simulation, the results predicted by the EMMS drag model showed a better agreement with the experimental axial average pressure drop and apparent solid volume fraction, which proves that the revised drag force based on the EMMS model is an appropriate model for the dense CFB simulation.

Development of a Two-fluid Drag Law for Clustered Particles using Direct Numerical Simulation and Validation through Experiments

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

Gokaltun, Seckin; Munroe, Norman; Subramaniam, Shankar

2014-12-31

This study presents a new drag model, based on the cohesive inter-particle forces, implemented in the MFIX code. This new drag model combines an existing standard model in MFIX with a particle-based drag model based on a switching principle. Switches between the models in the computational domain occur where strong particle-to-particle cohesion potential is detected. Three versions of the new model were obtained by using one standard drag model in each version. Later, performance of each version was compared against available experimental data for a fluidized bed, published in the literature and used extensively by other researchers for validation purposes.more » In our analysis of the results, we first observed that standard models used in this research were incapable of producing closely matching results. Then, we showed for a simple case that a threshold is needed to be set on the solid volume fraction. This modification was applied to avoid non-physical results for the clustering predictions, when governing equation of the solid granular temperate was solved. Later, we used our hybrid technique and observed the capability of our approach in improving the numerical results significantly; however, improvement of the results depended on the threshold of the cohesive index, which was used in the switching procedure. Our results showed that small values of the threshold for the cohesive index could result in significant reduction of the computational error for all the versions of the proposed drag model. In addition, we redesigned an existing circulating fluidized bed (CFB) test facility in order to create validation cases for clustering regime of Geldart A type particles.« less

State-of-the-art review of computational fluid dynamics modeling for fluid-solids systems

NASA Astrophysics Data System (ADS)

Lyczkowski, R. W.; Bouillard, J. X.; Ding, J.; Chang, S. L.; Burge, S. W.

1994-05-01

As the result of 15 years of research (50 staff years of effort) Argonne National Laboratory (ANL), through its involvement in fluidized-bed combustion, magnetohydrodynamics, and a variety of environmental programs, has produced extensive computational fluid dynamics (CFD) software and models to predict the multiphase hydrodynamic and reactive behavior of fluid-solids motions and interactions in complex fluidized-bed reactors (FBR's) and slurry systems. This has resulted in the FLUFIX, IRF, and SLUFIX computer programs. These programs are based on fluid-solids hydrodynamic models and can predict information important to the designer of atmospheric or pressurized bubbling and circulating FBR, fluid catalytic cracking (FCC) and slurry units to guarantee optimum efficiency with minimum release of pollutants into the environment. This latter issue will become of paramount importance with the enactment of the Clean Air Act Amendment (CAAA) of 1995. Solids motion is also the key to understanding erosion processes. Erosion rates in FBR's and pneumatic and slurry components are computed by ANL's EROSION code to predict the potential metal wastage of FBR walls, intervals, feed distributors, and cyclones. Only the FLUFIX and IRF codes will be reviewed in the paper together with highlights of the validations because of length limitations. It is envisioned that one day, these codes with user-friendly pre- and post-processor software and tailored for massively parallel multiprocessor shared memory computational platforms will be used by industry and researchers to assist in reducing and/or eliminating the environmental and economic barriers which limit full consideration of coal, shale, and biomass as energy sources; to retain energy security; and to remediate waste and ecological problems.

40 CFR 60.155 - Reporting.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (a) The owner or operator of any multiple hearth, fluidized bed, or electric sludge incinerator... than 3 percent. (b) The owner or operator of any multiple hearth, fluidized bed, or electric sludge... over each 1-hour incinerator operating period. (3) Temperatures of every hearth in multiple hearth...

PARTICULATE EMISSIONS AND CONTROL IN FLUIDIZED-BED COMBUSTION: MODELING AND PARAMETRIC PERFORMANCE

EPA Science Inventory

The report discusses a model, developed to describe the physical characteristics of the particulates emitted from fluidized-bed combustion (FBC) systems and to evaluate data on FBC particulate control systems. The model, which describes the particulate emissions profile from FBC,...

Fluidization, resolidification, and reorientation of the endothelial cell in response to slow tidal stretches

PubMed Central

Krishnan, Ramaswamy; Canović, Elizabeth Peruski; Iordan, Andreea L.; Rajendran, Kavitha; Manomohan, Greeshma; Pirentis, Athanassios P.; Smith, Michael L.; Butler, James P.; Fredberg, Jeffrey J.

2012-01-01

Mechanical stretch plays an important role in regulating shape and orientation of the vascular endothelial cell. This morphological response to stretch is basic to angiogenesis, neovascularization, and vascular homeostasis, but mechanism remains unclear. To elucidate mechanisms, we used cell mapping rheometry to measure traction forces in primary human umbilical vein endothelial cells subjected to periodic uniaxial stretches. Onset of periodic stretch of 10% strain amplitude caused a fluidization response typified by attenuation of traction forces almost to zero. As periodic stretch continued, the prompt fluidization response was followed by a slow resolidification response typified by recovery of the traction forces, but now aligned along the axis perpendicular to the imposed stretch. Reorientation of the cell body lagged reorientation of the traction forces, however. Together, these observations demonstrate that cellular reorientation in response to periodic stretch is preceded by traction attenuation by means of cytoskeletal fluidization and subsequent traction recovery transverse to the stretch direction by means of cytoskeletal resolidification. PMID:22700796

Industrial demonstration plant for the gasification of herb residue by fluidized bed two-stage process.

PubMed

Zeng, Xi; Shao, Ruyi; Wang, Fang; Dong, Pengwei; Yu, Jian; Xu, Guangwen

2016-04-01

A fluidized bed two-stage gasification process, consisting of a fluidized-bed (FB) pyrolyzer and a transport fluidized bed (TFB) gasifier, has been proposed to gasify biomass for fuel gas production with low tar content. On the basis of our previous fundamental study, an autothermal two-stage gasifier has been designed and built for gasify a kind of Chinese herb residue with a treating capacity of 600 kg/h. The testing data in the operational stable stage of the industrial demonstration plant showed that when keeping the reaction temperatures of pyrolyzer and gasifier respectively at about 700 °C and 850 °C, the heating value of fuel gas can reach 1200 kcal/Nm(3), and the tar content in the produced fuel gas was about 0.4 g/Nm(3). The results from this pilot industrial demonstration plant fully verified the feasibility and technical features of the proposed FB two-stage gasification process. Copyright © 2016. Published by Elsevier Ltd.

Air-fluidized grains as a model system: Self-propelling and jamming

NASA Astrophysics Data System (ADS)

Daniels, Lynn J.

This thesis examines two concepts -- self-propelling and jamming -- that have been employed to unify disparate non-equilibrium systems, in the context of a monolayer of grains fluidized by a temporally and spatially homogeneous upflow of air. The first experiment examines the single particle dynamics of air-fluidized rods. For Brownian rods, equipartition of energy holds and rotational motion sets a timescale after which directional memory is lost. Air-fluidized rods no longer obey equipartion; they self-propel, moving preferentially along their long axis. We show that self-propelling can be treated phenomenologically as an enhanced memory effect causing directional memory to persist for times longer than expected for thermal systems. The second experiment studies dense collections of self-propelling air-fluidized rods. We observe collective propagating modes that give rise to anomalously large fluctuations in the local number density. We quantify these compression waves by calculating the dynamic structure factor and show that the wavespeed is weakly linear with increasing density. It has been suggested that the observed behavior might be explained using the framework put forth by Baskaran et al. [12]. The third experiment seeks to determine whether a force analogous to the critical Casimir force in fluids exists for a large sphere fluidized in the presence of a background of smaller spheres. The behavior of such a large sphere is fully characterized showing that, rather than behaving like a sphere driven by turbulence, the large ball self-propels. We also show that the background is responsible for the purely attractive, intermediate-ranged interaction force between two simultaneously-fluidized large balls. The final experiment seeks to determine what parameters control the diverging relaxation timescale associated with the jamming transition. By tilting our apparatus, we quantify pressure, packing fraction, and temperature simultaneously with dynamics as we approach jamming. We obtain an equation of state that agrees well with simulation and free volume theory. We collapse the relaxation time by defining a time- and energy-scale using pressure, consistent with recent simulation [82]. These experiments are further confirmation of the universality of the concepts of self-propelling and jamming.

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.

Process for converting cellulosic materials into fuels and chemicals

DOEpatents

Scott, Charles D.; Faison, Brendlyn D.; Davison, Brian H.; Woodward, Jonathan

1994-01-01

A process for converting cellulosic materials, such as waste paper, into fuels and chemicals utilizing enzymatic hydrolysis of the major constituent of paper, cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. The cellulase is produced from a continuous, columnar, fluidized-bed bioreactor utilizing immobilized microorganisms. An attritor and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. The cellulase is recycled by an adsorption process. The resulting crude sugars are converted to dilute product in a fluidized-bed bioreactor utilizing microorganisms. The dilute product is concentrated and purified by utilizing distillation and/or a biparticle fluidized-bed bioreactor system.

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.

Fluidized-bed combustion reduces atmospheric pollutants

NASA Technical Reports Server (NTRS)

Jonke, A. A.

1972-01-01

Method of reducing sulfur and nitrogen oxides released during combustion of fossil fuels is described. Fuel is burned in fluidized bed of solids with simultaneous feeding of crushed or pulverized limestone to control emission. Process also offers high heat transfer rates and efficient contacting for gas-solid reactions.

The contribution of air-fluidization to the mobility of rapid flowslides involving fine particles

NASA Astrophysics Data System (ADS)

Stilmant, Frédéric; Dewals, Benjamin; Archambeau, Pierre; Erpicum, Sébastien; Pirotton, Michel

2016-04-01

Air-fluidization can be the origin of the long runout of gravitational flows involving fine particles such as ash. An excessive air pore pressure dramatically reduces the friction angle of the material as long as this pressure has not been dissipated, which occurs during the flow. This phenomenon can be modelled thanks to the 2D depth-averaged equations of mass and momentum conservation and an additional transport equation for basal pore pressure evolution (Iverson and Denlinger, 2001). In this contribution, we discuss the application of this model in relation to recent experimental results on air-fluidized flows by Roche et al. (2008) and Roche (2012). The experimental results were used to set a priori the value of the diffusion coefficient in the model, taking into account the difference of scale between the experiments and real-world applications. We also compare the model predictions against detailed observations of a well-documented historical event, the collapse of a fly-ash heap in Belgium (Stilmant et al., 2015). In particular, we analyse the influence of the different components of the model on the results (pore pressure dissipation vs. pore pressure generation). The diffusion coefficient which characterizes the dissipation of air pore pressure is found sufficiently low for maintaining a fluidized flow over hundreds of meters. The study concludes that an air-fluidization theory is consistent with the field observations. These findings are particularly interesting as they seem not in line with the mainstream acceptation in landslide modelling that air generally plays a secondary role (e.g., Legros, 2002). References Iverson, R.M., Denlinger, R.P., 2001. Flow of variably fluidized granular masses across three-dimensional terrain - 1. Coulomb mixture theory. J. Geophys. Res. 106, 537 552. Legros, F., 2002. The mobility of long-runout landslides. Eng. Geol. 63, 301-331. Roche, O., 2012. Depositional processes and gas pore pressure in pyroclastic flows: an experimental perspective. Bull. Volcanol. 74, 1807-1820. Roche, O., Montserrat, S., Niño, Y., Tamburrino, A., 2008. Experimental observations of water-like behavior of initially fluidized, dam break granular flows and their relevance for the propagation of ash-rich pyroclastic flows. J. Geophys. Res. 113, B12203. Stilmant, F., Pirotton, M., Archambeau, P., Erpicum, S., & Dewals, B. (2015). Can the collapse of a fly ash heap develop into an air-fluidized flow? - Reanalysis of the Jupille accident (1961). Geomorphology, 228, 746-755.

Researching of the reduction of shock waves intensivity in the “pseudo boiling” layer

NASA Astrophysics Data System (ADS)

Pavlov, G. I.; Telyashov, D. A.; Kochergin, A. V.; Nakoryakov, P. V.; Sukhovaya, E. A.

2017-09-01

This article applies to the field of acoustics and deals with noise reduction of pulsating combustion chambers, in particular the reduction of the shock waves’ intensity with the help of pseudo boiling layer. In the course of work on a test stand that included a pulsator, a compressor with the receiver and a high pressure fan was simulated gas jet flowing from the chamber pulsating combustion and studied the effect of different types of fluidization on effect of reducing the sound pressure levels. Were obtained the experimental dependence of the sound pressure levels from parameters such as: height of the layer of granules; diameter of the used granules; amplitude of the pressure pulsations in the gas stream at the entrance to the camera; frequency of pressure pulsations. Based on the results of the study, it was concluded that the using of a pseudo boiling layer is promising for reducing shock wave noise.

Physicochemical properties and gasification reactivity of the ultrafine semi-char derived from a bench-scale fluidized bed gasifier

NASA Astrophysics Data System (ADS)

Zhang, Yukui; Zhang, Haixia; Zhu, Zhiping; Na, Yongjie; Lu, Qinggang

2017-08-01

Zhundong coalfield is the largest intact coalfield worldwide and fluidized bed gasification has been considered as a promising way to achieve its clean and efficient utilization. The purpose of this study is to investigate the physicochemical properties and gasification reactivity of the ultrafine semi-char, derived from a bench-scale fluidized bed gasifier, using Zhundong coal as fuel. The results obtained are as follows. In comparison to the raw coal, the carbon and ash content of the semi-char increase after partial gasification, but the ash fusion temperatures of them show no significant difference. Particularly, 76.53% of the sodium in the feed coal has released to the gas phase after fluidized bed gasification. The chemical compositions of the semi-char are closely related to its particle size, attributable to the distinctly different natures of diverse elements. The semi-char exhibits a higher graphitization degree, higher BET surface area, and richer meso- and macropores, which results in superior gasification reactivity than the coal char. The chemical reactivity of the semi-char is significantly improved by an increased gasification temperature, which suggests the necessity of regasification of the semi-char at a higher temperature. Consequently, it will be considered feasible that these carbons in the semi-char from fluidized bed gasifiers are reclaimed and reused for the gasification process.

A comparison between the four Geldart groups on the performance of a gas-phase annular fluidized bed photoreactor for volatile organic compound oxidation.

PubMed

Diniz, Leonardo Almeida; Hewer, Thiago Lewis Reis; Matsumoto, Danielle; Teixeira, Antonio Carlos Silva Costa

2018-05-07

Heterogeneous photocatalytic oxidation (PCO) is a widely studied alternative for the elimination of volatile organic compounds (VOC) in air. In this context, research on novel photoreactor arrangements to enhance PCO rates is desired. Annular fluidized bed photoreactors (AFBPR) have yielded prominent results when compared to conventional thin film reactors. However, very few works aimed at optimizing AFBPR operation. In this study, TiO 2 photocalytic agglomerates were synthesized and segregated in specific size distributions to behave as Geldart groups A, B, C, and D fluidization. The TiO 2 agglomerates were characterized by XRD, FTIR spectra, and N 2 adsorption. Photocatalyst performances were compared in a 10-mm gapped AFBPR for degrading the model pollutant methyl-ethyl-ketone (MEK), using a 254-nm radiation source. Geldart group C showed to be inadequate for AFBPR operation due to the short operation range between fluidization and elutriation. In all the cases, photocatalytic reaction rates were superior to sole UV photolysis. Group A and group B demonstrated the highest reaction rates. Considerations based on mass transfer suggested that the reasons were enhanced UV distribution within the bed at lower flow rates and superior catalyst surface area at higher flow rates. Results also revealed that groups A, B, and D perform equally per catalyst area within an AFBPR if the fluidization numbers (FN) are high enough.

Flying MOFs: polyamine-containing fluidized MOF/SiO2 hybrid materials for CO2 capture from post-combustion flue gas.

PubMed

Luz, Ignacio; Soukri, Mustapha; Lail, Marty

2018-05-28

Solid-state synthesis ensures a high loading and well-dispersed growth of a large collection of metal-organic framework (MOF) nanostructures within a series of commercially available mesoporous silica. This approach provides a general, highly efficient, scalable, environmentally friendly, and inexpensive strategy for shaping MOFs into a fluidized form, thereby allowing their application in fluidized-bed reactors for diverse applications, such as CO 2 capture from post-combustion flue gas. A collection of polyamine-impregnated MOF/SiO 2 hybrid sorbents were evaluated for CO 2 capture under simulated flue gas conditions in a packed-bed reactor. Hybrid sorbents containing a moderate loading of (Zn)ZIF-8 are the most promising sorbents in terms of CO 2 adsorption capacity and long-term stability (up to 250 cycles in the presence of contaminants: SO 2 , NO x and H 2 S) and were successfully prepared at the kilogram scale. These hybrid sorbents demonstrated excellent fluidizability and performance under the relevant process conditions in a visual fluidized-bed reactor. Moreover, a biochemically inspired strategy for covalently linking polyamines to MOF/SiO 2 through strong phosphine bonds has been first introduced in this work as a powerful and highly versatile post-synthesis modification for MOF chemistry, thus providing a novel alternative towards more stable CO 2 solid sorbents.

SIMULTANEOUS CAPTURE OF METAL, SULFUR AND CHLORINE BY SORBENTS DURING FLUIDIZED BED INCINERATION. (R826694C697)

EPA Science Inventory

Metal capture experiments were carried out in an atmospheric fluidized bed incinerator to investigate the effect of sulfur and chlorine on metal capture efficiency and the potential for simultaneous capture of metal, sulfur and chlorine by sorbents. In addition to experimental...

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 ...

CONTINUOUS MICRO-SORTING OF COMPLEX WASTE PLASTICS PARTICLEMIXTURES VIA LIQUID-FLUIDIZED BED CLASSIFICATION (LFBC) FOR WASTE MINIMIZATIONAND RECYCLING

EPA Science Inventory

A fundamental investigation is proposed to provide a technical basis for the development of a novel, liquid-fluidized bed classification (LFBC) technology for the continuous separation of complex waste plastic mixtures for in-process recycling and waste minimization. Although ...

Numerical study of heat and mass transfer in inertial suspensions in pipes.

NASA Astrophysics Data System (ADS)

Niazi Ardekani, Mehdi; Brandt, Luca

2017-11-01

Controlling heat and mass transfer in particulate suspensions has many important applications such as packed and fluidized bed reactors and industrial dryers. In this work, we study the heat and mass transfer within a suspension of spherical particles in a laminar pipe flow, using the immersed boundary method (IBM) to account for the solid fluid interactions and a volume of fluid (VoF) method to resolve temperature equation both inside and outside of the particles. Tracers that follow the fluid streamlines are considered to investigate mass transfer within the suspension. Different particle volume fractions 5, 15, 30 and 40% are simulated for different pipe to particle diameter ratios: 5, 10 and 15. The preliminary results quantify the heat and mass transfer enhancement with respect to a single-phase laminar pipe flow. We show in particular that the heat transfer from the wall saturates for volume fractions more than 30%, however at high particle Reynolds numbers (small diameter ratios) the heat transfer continues to increase. Regarding the dispersion of tracer particles we show that the diffusivity of tracers increases with volume fraction in radial and stream-wise directions however it goes through a peak at 15% in the azimuthal direction. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

Interaction of Burning Metal Particles

NASA Technical Reports Server (NTRS)

Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

1999-01-01

Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 micrometer diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 micrometer diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands form the thermal black body radiation. Recorded flame images were digitized and employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishing as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

Controlled Viscosity in Dense Granular Materials

NASA Astrophysics Data System (ADS)

Gnoli, A.; de Arcangelis, L.; Giacco, F.; Lippiello, E.; Ciamarra, M. Pica; Puglisi, A.; Sarracino, A.

2018-03-01

We experimentally investigate the fluidization of a granular material subject to mechanical vibrations by monitoring the angular velocity of a vane suspended in the medium and driven by an external motor. On increasing the frequency, we observe a reentrant transition, as a jammed system first enters a fluidized state, where the vane rotates with high constant velocity, and then returns to a frictional state, where the vane velocity is much lower. While the fluidization frequency is material independent, the viscosity recovery frequency shows a clear dependence on the material that we rationalize by relating this frequency to the balance between dissipative and inertial forces in the system. Molecular dynamics simulations well reproduce the experimental data, confirming the suggested theoretical picture.

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.

Process for converting cellulosic materials into fuels and chemicals

DOEpatents

Scott, C.D.; Faison, B.D.; Davison, B.H.; Woodward, J.

1994-09-20

A process is described for converting cellulosic materials, such as waste paper, into fuels and chemicals utilizing enzymatic hydrolysis of the major constituent of paper, cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. The cellulase is produced from a continuous, columnar, fluidized-bed bioreactor utilizing immobilized microorganisms. An attrition mill and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. The cellulase is recycled by an adsorption process. The resulting crude sugars are converted to dilute product in a fluidized-bed bioreactor utilizing microorganisms. The dilute product is concentrated and purified by utilizing distillation and/or a biparticle fluidized-bed bioreactor system. 1 fig.

Fluidized bed gasification of extracted coal

DOEpatents

Aquino, Dolores C.; DaPrato, Philip L.; Gouker, Toby R.; Knoer, Peter

1986-01-01

Coal or similar carbonaceous solids are extracted by contacting the solids in an extraction zone (12) with an aqueous solution having a pH above 12.0 at a temperature between 65.degree. C. and 110.degree. C. for a period of time sufficient to remove bitumens from the coal into said aqueous solution and the extracted solids are then gasified at an elevated pressure and temperature in a fluidized bed gasification zone (60) wherein the density of the fluidized bed is maintained at a value above 160 kg/m.sup.3. In a preferred embodiment of the invention, water is removed from the aqueous solution in order to redeposit the extracted bitumens onto the solids prior to the gasification step.

Decontamination of combustion gases in fluidized bed incinerators

DOEpatents

Leon, Albert M.

1982-01-01

Sulfur-containing atmospheric pollutants are effectively removed from exit gas streams produced in a fluidized bed combustion system by providing a fluidized bed of particulate material, i.e. limestone and/or dolomite wherein a concentration gradient is maintained in the vertical direction. Countercurrent contacting between upwardly directed sulfur containing combustion gases and descending sorbent particulate material creates a concentration gradient across the vertical extent of the bed characterized in progressively decreasing concentration of sulfur, sulfur dioxide and like contaminants upwardly and decreasing concentration of e.g. calcium oxide, downwardly. In this manner, gases having progressively decreasing sulfur contents contact correspondingly atmospheres having progressively increasing concentrations of calcium oxide thus assuring optimum sulfur removal.

West Virginia Geological Survey's role in siting fluidized bed combustion facilities

USGS Publications Warehouse

Smith, C.J.; King, Hobart M.; Ashton, K.C.; Kirstein, D.S.; McColloch, G.H.

1989-01-01

A project is presented which demonstrates the role of geology in planning and siting a fluidized bed combustion facility. Whenever a project includes natural resource utilization, cooperation between geologists and design engineers will provide an input that could and should save costs, similar to the one stated in our initial premise. Regardless of whether cost reductions stem from a better knowledge of fuel and sorbent availabilities, or a better understanding of the local hydrology, susceptibility to mine-subsidence, or other geologic hazards, the geological survey has a vital role in planning. Input to planning could help the fluidized-bed developer and design-engineer solve some economic questions and stretch the financial resources at their disposal.

The Mechanics of Peak-Ring Impact Crater Formation from the IODP-ICDP Expedition 364

NASA Astrophysics Data System (ADS)

Melosh, H.; Collins, G. S.; Morgan, J. V.; Gulick, S. P. S.

2017-12-01

The Chicxulub impact crater is one of very few peak-ring impact craters on Earth. While small (less than 3 km on Earth) impact craters are typically bowl-shaped, larger craters exhibit central peaks, which in still larger (more than about 100 km on Earth) craters expand into mountainous rings with diameters close to half that of the crater rim. The origin of these peak rings has been contentious: Such craters are far too large to create in laboratory experiments and remote sensing of extraterrestrial examples has not clarified the mechanics of their formation. Two principal models of peak ring formation are currently in vogue, the "nested crater" model, in which the peak ring originates at shallow depths in the target, and the "dynamic collapse" model in which the peak ring is uplifted at the base of a collapsing, over-steepened central peak and its rocks originate at mid-crustal depths. IODP-ICDP Expedition 364 sought to elucidate, among other important goals, the mechanics of peak ring formation in the young (66 Myr), fresh, but completely buried Chicxulub impact crater. The cores from this borehole now show unambiguously that the rocks in the Chicxulub peak ring originated at mid-crustal depths, apparently ruling out the nested crater model. These rocks were shocked to pressures on the order of 10-35 GPa and were so shattered that their densities and seismic velocities now resemble those of sedimentary rocks. The morphology of the final crater, its structure as revealed in previous seismic imaging, and the results from the cores are completely consistent with modern numerical models of impact crater excavation and collapse that incorporate a model for post-impact weakening. Subsequent to the opening of a ca. 100 km diameter and 30 km deep transient crater, this enormous hole in the crust collapsed over a period of about 10 minutes. Collapse was enabled by movement of the underlying rocks, which briefly behaved in the manner of a high-viscosity fluid, a brittle deformation state described by the process of "acoustic" fluidization initiated by strong elastic vibrations accompanying the opening and collapse of the crater. The shattered core, cut by both melt rock and clastic dikes, is consistent with the block model of acoustic fluidization supporting its application to crater collapse both on the Earth and on other planets.

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

Gangwal, S.K.; Gupta, R.P.; Khare, G.P.

The objectives of this project are to determine the long-term chemical reactivity and mechanical durability of a fluidized version of Phillips Petroleum Company`s proprietary Z-SORB sorbent for the desulfurization of coal-derived gases in a high-pressure (20 atm) fluidized-bed reactor under simulated U-Gas conditions and at a moderate operating temperature of 538 degrees C.

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…

Soil Chemistry Still Affected 23 Years After Large Application of Fluidized Bed Material

USDA-ARS?s Scientific Manuscript database

This study was conducted to assess the movement of arsenic, aluminum, calcium, copper, iron, lead, magnesium, manganese, mercury and zinc in an old apple (Malus domestica Borkh) orchard that received a one time application of 36 kg/ m2 of fluidized bed combustion material (FBCM) 23 years earlier. S...

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.

Propagation of a fluidization - combustion wave

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

Pron, G.P.; Gusachenko, L.K.; Zarko, V.E.

1994-05-01

A fluidization-combustion wave propagating through a fixed and initially cool bed was created by igniting coal at the top surface of the bed. The proposed physical interpretation of the phenomenon is in qualitative agreement with the experimental dependences of the characteristics of the process on determining parameters. A kindling regime with forced wave propagation is suggested.

Gas stream clean-up filter and method for forming same

DOEpatents

Mei, Joseph S.; DeVault, James; Halow, John S.

1993-01-01

A gas cleaning filter is formed in-situ within a vessel containing a fluidizable bed of granular material of a relatively large size fraction. A filter membrane provided by a porous metal or ceramic body or such a body supported a perforated screen on one side thereof is coated in-situ with a layer of the granular material from the fluidized bed by serially passing a bed-fluidizing gas stream through the bed of granular material and the membrane. The layer of granular material provides the filtering medium for the combined membrane-granular layer filter. The filter is not blinded by the granular material and provides for the removal of virtually all of the particulates from a process gas stream. The granular material can be at least partially provided by a material capable of chemically reacting with and removing sulfur compounds from the process gas stream. Low level radioactive waste containing organic material may be incinerated in a fluidized bed in communication with the described filter for removing particulates from the gaseous combustion products.

Method of pyrolyzing brown coal

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

Michel, W.; Heberlein, I.; Ossowski, M.

A two-step method and apparatus are disclosed based on the fluidized bed principle, for the production of coke, rich gas and pyrolysis tar, with the object of executing the method in a compact apparatus arrangement, with high energy efficiency and high throughput capacity. This is accomplished by a sequence in which the fine grains removed from the drying vapor mixture are removed from the actual pyrolysis process, and a hot gas, alien to the carbonization, is used as fluidization medium in the pyrolysis reactor, and with a hot gas-high performance separator being used for the dust separation from the pyrolysismore » gas, with the combustion exhaust gas produced in the combustion chamber being used for the indirect heating of the fluidization medium, for the pre-heating of the gas, which is alien to the carbonization, and for the direct heating in the dryer. The dryer has a double casing in the area of the fluidized bed, and a mixing chamber is arranged directly underneath its initial flow bottom, while the pyrolysis reactor is directly connected to the combustion chamber and the pre-heater.« less

Wall fluidization in two acts: from stiff to soft roughness.

PubMed

Derzsi, Ladislav; Filippi, Daniele; Lulli, Matteo; Mistura, Giampaolo; Bernaschi, Massimo; Garstecki, Piotr; Sbragaglia, Mauro; Pierno, Matteo

2018-02-14

Fluidization of soft glassy materials (SGMs) in microfluidic channels is affected by the wall roughness in the form of microtexturing. When SGMs flow across microgrooves, their constituents are likely trapped within the grooves' gap, and the way they are released locally modifies the fluidization close to the walls. By leveraging a suitable combination of experiments and numerical simulations on concentrated emulsions (a model SGM), we quantitatively report the existence of two physically different scenarios. When the gap is large compared to the droplets in the emulsion, the droplets hit the solid obstacles and easily escape scrambling with their neighbors. Conversely, as the gap spacing is reduced, droplets get trapped inside, creating a "soft roughness" layer, i.e. a complementary series of deformable posts from which overlying droplets are in turn released. In both cases, the induced fluidization scales with the grooves' density, although with a reduced prefactor for narrow gaps, accounting for the softness of the roughness. Both scenarios are also well distinguished via the statistics of the droplets displacement field close to the walls, with large deviations induced by the surface roughness, depending on its stiffness.

Heat transfer to horizontal tubes immersed in a fluidized-bed combustor

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

Grewal, N.S.; Menart, J.; Hajicek, D.R.

Experiments were carried out to measure the heat transfer rates to water-cooled horizontal tubes immersed in an atmospheric fluidized-bed combustor burning North Dakota lignite. The effect of bed temperature (T/sub B/ = 587 to 1205K), particle size (anti d/sub p/ = 0.544 to 2.335 mm), and fluidizing velocity (U = 0.73 to 2.58 m/s) on the heat transfer rate to horizontal tubes immersed in a fluidized-bed combustor (0.45 x 0.45 m) was investigated. Among existing correlations, correlations proposed by Glicksman and Decker (1980), Zabrodsky et al. (1980), Catipovic et al. (1980), Grewal (1981), and Bansal et al. (1980) are foundmore » to predict the present data quite well, when the contribution due to radiation is included. The radiative heat transfer is estimated as the difference between the heat transfer to an oxidized boiler tube and to a gold-plated tube. The relative contribution of radiation is found to be 11% for a bed of sand particles (anti d/sub p/ = 0.9 mm) operating at 1088K. 40 refs., 7 figs., 5 tabs.« less

The influence of recycling non-condensable gases in the fractional catalytic pyrolysis of biomass.

PubMed

Mante, Ofei D; Agblevor, F A; Oyama, S T; McClung, R

2012-05-01

In this study, the effect of recycling the non-condensable gases (NCG) in the catalytic pyrolysis of hybrid poplar using FCC catalyst was investigated. A 50mm bench scale fluidized bed reactor at 475°C with a weight hourly space velocity (WHSV) of 2h(-1) and a gas recycling capability was used for the studies. Model fluidizing gas mixtures of CO/N(2), CO(2)/N(2), CO/CO(2)/N(2) and H(2)/N(2) were used to determine their independent effects. Recycling of the NCG in the process was found to potentially increase the liquid yield and decrease char/coke yield. The model fluidizing gases increased the liquid yield and the CO(2)/N(2) fluidizing gas had the lowest char/coke yield. The (13)C-NMR analysis showed that recycling of NCG increases the aromatic fractions and decreases the methoxy, carboxylic and sugar fractions. Recycling of NCG increased the higher heating value and the pH of the bio-oil as well as decreased the viscosity and density. Copyright © 2012 Elsevier Ltd. All rights reserved.

Impact Cratering Calculations

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.

2002-01-01

Many Martian craters are surrounded by ejecta blankets which appear to have been fluidized forming lobate and layered deposits terminated by one or more continuous distal scarps, or ramparts. One of the first hypotheses for the formation of so-called rampart ejecta features was shock-melting of subsurface ice, entrainment of liquid water into the ejecta blanket, and subsequent fluidized flow. Our work quantifies this concept. Rampart ejecta found on all but the youngest volcanic and polar regions, and the different rampart ejecta morphologies are correlated with crater size and terrain. In addition, the minimum diameter of craters with rampart features decreases with increasing latitude indicating that ice laden crust resides closer to the surface as one goes poleward on Mars. Our second goal in was to determine what strength model(s) reproduce the faults and complex features found in large scale gravity driven craters. Collapse features found in large scale craters require that the rock strength weaken as a result of the shock processing of rock and the later cratering shear flows. In addition to the presence of molten silicate in the intensely shocked region, the presence of water, either ambient, or the result of shock melting of ice weakens rock. There are several other mechanisms for the reduction of strength in geologic materials including dynamic tensile and shear induced fracturing. Fracturing is a mechanism for large reductions in strength. We found that by incorporating damage into the models that we could in a single integrated impact calculation, starting in the atmosphere produce final crater profiles having the major features found in the field measurements (central uplifts, inner ring, terracing and faulting). This was accomplished with undamaged surface strengths (0.1 GPa) and in depth strengths (1.0 GPa).

Urea encapsulation in modified starch matrix for nutrients retention

NASA Astrophysics Data System (ADS)

Naz, Muhammad Yasin; Sulaiman, Shaharin Anwar; Ariff, Mohd. Hazwan Bin Mohd.; Ariwahjoedi, Bambang

2014-10-01

It has been estimated that 20-70% of the used urea goes to the environment via leaching, nitrification and volatilization which not only harms the environment but also reduces the urea efficiency. By coating the urea granules, the farmers can achieve high urea performance through controlling the excess release of nitrogen. Up until now, different materials have been tested for nutrients retention. However, most of them are either expensive or unfriendly to the environment. Being cheap and biodegradable materials, the starches may also be used to coat the urea fertilizer for controlling the nutrients release. However, the pure starches do not meet the standards set by many industrial processes due to their slow tacking and too low viscosities and should be modified for getting smooth, compact and mechanically stronger coatings. In these studies, the tapioca starch was modified by reacting it with urea and different masses of borax. The prepared solutions were used to coat the urea granules of 3.45 mm average diameter. Different volumes (1, 1.5 and 2 mL) of each solution were used to coat 30 g of urea fluidized above the minimum level of fluidization. It was noticed that the coating thickness, percent coating, dissolution rate and percent release follow an increasing trend with an increase of solution volume; however, some random results were obtained while investigating the solution volume effects on the percent release. It was seen that the nutrients percent release over time increases with an increase in solution volume from 1 to 1.5 mL and thereafter reaches to a steady state. It confirms that the 1.5 mL of solution for 30 g urea samples will give the optimized coating results.

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.

Rampart craters on Ganymede: Their implications for fluidized ejecta emplacement

NASA Astrophysics Data System (ADS)

Boyce, Joseph; Barlow, Nadine; Mouginis-Mark, Peter; Stewart, Sarah

2010-04-01

Some fresh impact craters on Ganymede have the overall ejecta morphology similar to Martian double-layer ejecta (DLE), with the exception of the crater Nergal that is most like Martian single layer ejecta (SLE) craters (as is the terrestrial crater Lonar). Similar craters also have been identified on Europa, but no outer ejecta layer has been found on these craters. The morphometry of these craters suggests that the types of layered ejecta craters identified by Barlow et al. (2000) are fundamental. In addition, the mere existence of these craters on Ganymede and Europa suggests that an atmosphere is not required for ejecta fluidization, nor can ejecta fluidization be explained by the flow of dry ejecta. Moreover, the absence of fluidized ejecta on other icy bodies suggests that abundant volatiles in the target also may not be the sole cause of ejecta fluidization. The restriction of these craters to the grooved terrain of Ganymede and the concentration of Martian DLE craters on the northern lowlands suggests that these terrains may share key characteristics that control the development of the ejecta of these craters. In addition, average ejecta mobility (EM) ratios indicate that the ejecta of these bodies are self-similar with crater size, but are systematically smaller on Ganymede and Europa. This may be due to the effects of the abundant ice in the crusts of these satellites that results in increased ejection angle causing ejecta to impact closer to the crater and with lower horizontal velocity.

Fluidized bed steam reformed mineral waste form performance testing to support Hanford Supplemental Low Activity Waste Immobilization Technology Selection

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

Jantzen, C. M.; Pierce, E. M.; Bannochie, C. J.

This report describes the benchscale testing with simulant and radioactive Hanford Tank Blends, mineral product characterization and testing, and monolith testing and characterization. These projects were funded by DOE EM-31 Technology Development & Deployment (TDD) Program Technical Task Plan WP-5.2.1-2010-001 and are entitled “Fluidized Bed Steam Reformer Low-Level Waste Form Qualification”, Inter-Entity Work Order (IEWO) M0SRV00054 with Washington River Protection Solutions (WRPS) entitled “Fluidized Bed Steam Reforming Treatability Studies Using Savannah River Site (SRS) Low Activity Waste and Hanford Low Activity Waste Tank Samples”, and IEWO M0SRV00080, “Fluidized Bed Steam Reforming Waste Form Qualification Testing Using SRS Low Activity Wastemore » and Hanford Low Activity Waste Tank Samples”. This was a multi-organizational program that included Savannah River National Laboratory (SRNL), THOR® Treatment Technologies (TTT), Pacific Northwest National Laboratory (PNNL), Oak Ridge National Laboratory (ORNL), Office of River Protection (ORP), and Washington River Protection Solutions (WRPS). The SRNL testing of the non-radioactive pilot-scale Fluidized Bed Steam Reformer (FBSR) products made by TTT, subsequent SRNL monolith formulation and testing and studies of these products, and SRNL Waste Treatment Plant Secondary Waste (WTP-SW) radioactive campaign were funded by DOE Advanced Remediation Technologies (ART) Phase 2 Project in connection with a Work-For-Others (WFO) between SRNL and TTT.« less

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.

Coronary Collateral Growth—Back to the Future

PubMed Central

Chilian, William M.; Penn, Marc S.; Pung, Yuh Fen; Dong, Feng; Mayorga, Maritza; Ohanyan, Vahagn; Logan, Suzanna; Yin, Liya

2012-01-01

The coronary collateral circulation is critically important as an adaptation of the heart to prevent the damage from ischemic insults. In their native state, collaterals in the heart would be classified as part of the microcirculation, existing as arterial-arterial anastomotic connections in the range of 30 to 100 μM in diameter. However, these vessels also show a propensity to remodel into components of the macrocirculation and can become arteries larger than a 1000 μM in diameter. This process of outward remodelling is critically important in the adaptation of the heart to ischemia because the resistance to blood flow is inversely related to the fourth power of the diameter of the vessel. Thus, an expansion of a vessel from 100 to 1000 μM would reduce resistance (in this part of the circuit) to a negligible amount and enable delivery of flow to the region at risk. Our goal in this review is to highlight the voids in understanding this adaptation to ischemia—the growth of the coronary collateral circulation. In doing so we discuss the controversies and unknown aspects of the causal factors that stimulate growth of the collateral circulation, the role of genetics, and the role of endogenous stem and progenitor cells in the context of the normal, physiological situation and under more pathological conditions of ischemic heart disease or with some of the underlying risk factors, e.g., diabetes. The major conclusion of this review is that there are many gaps in our knowledge of coronary collateral growth and this knowledge is critical before the potential of stimulating collateralization in the hearts of patients can be realized. PMID:22210280

Skin permeation and retention of topical bead formulation containing tranexamic acid.

PubMed

Vijayakumar, Ajay; Baskaran, Rengarajan; Yoo, Bong Kyu

2017-02-01

The objective of this study is to develop a topical bead formulation of tranexamic acid (TA) which can be used concomitantly with laser treatment. The bead formulation of TA (TAB) was successfully prepared by fluidized bed drying method. Physicochemical properties of the TAB were evaluated in terms of chemical stability of TA and differential scanning calorimetry. TA in the bead was stable up to six months at 25°C and existed as amorphous state. In vitro skin permeation and in vivo skin retention of TA in the beads were significantly higher compared to a commercial product. When the bead was dissolved into distilled water and applied concomitantly with laser treatment, the amount of TA retained in the skin in the in vivo study was inversely proportional to the energy levels of laser treatment, indicating absorption into subcutaneous tissue and drainage to systemic circulation. Therefore, when laser treatment is used concomitantly with TAB, energy level should be very carefully monitored to avoid possible adverse events associated with systemic side effects of TA.

Study of Gas Solid Flow Characteristics in Cyclone Inlet Ducts of A300Mwe CFB Boiler

NASA Astrophysics Data System (ADS)

Tang, J. Y.; Lu, X. F.; Lai, J.; Liu, H. Z.

Gas solid flow characteristics in cyclone's inlet duct of a 300MW CFB boiler were studied in a cold circulating fluidized bed (CFB) experimental setup according to a 410t/h CFB boiler with a scale of 10∶1. Tracer particles were adopted in the experiment and their motion trajectories in the two kinds of cyclone's inlet ducts were photographed by a high-speed camera. By analyzing the motion trajectories of tracer particles, acceleration performance of particle phases in the two inlet ducts was obtained. Results indicate that the acceleration performance of particles in the long inlet duct is better than that in the short inlet duct, but the pressure drop of the long inlet duct is higher. Meanwhile, under the same operating conditions, both the separation efficiency and the pressure drop of the cyclone are higher when the cyclone is connected with the long inlet duct. Figs 11, Tabs 4 and refs 10.

3D-Simulation Of Concentration Distributions Inside Large-Scale Circulating Fluidized Bed Combustors

NASA Astrophysics Data System (ADS)

Wischnewski, R.; Ratschow, L.; Hartge, E. U.; Werthe, J.

With increasing size of modern CFB combustors the lateral mixing of fuels and secondary air gains more and more importance. Strong concentration gradients, which result from improper lateral mixing, can lead to operational problems, high flue gas emissions and lower boiler efficiencies. A 3D-model for the simulation of local gas and solids concentrations inside industrial-sized CFB boilers has been developed. The model is based on a macroscopic approach and considers all major mechanisms during fuel spreading and subsequent combustion of char and volatiles. Typical characteristics of modern boilers like staged combustion, a smaller cross-sectional area in the lower section of the combustion chamber and the co-combustion of additional fuels with coal can be considered. The 252 MWth combustor of Stadtwerke Duisburg AG is used for the validation of the model. A comprehensive picture of the local conditions inside the combustion chamber is achieved by the combination of local gas measurements and the three-dimensional simulation of concentration distributions.

Combustion characteristics and retention-emission of selenium during co-firing of torrefied biomass and its blends with high ash coal.

PubMed

Ullah, Habib; Liu, Guijian; Yousaf, Balal; Ali, Muhammad Ubaid; Abbas, Qumber; Zhou, Chuncai

2017-12-01

The combustion characteristics, kinetic analysis and selenium retention-emission behavior during co-combustion of high ash coal (HAC) with pine wood (PW) biomass and torrefied pine wood (TPW) were investigated through a combination of thermogravimetric analysis (TGA) and laboratory-based circulating fluidized bed combustion experiment. Improved ignition behavior and thermal reactivity of HAC were observed through the addition of a suitable proportion of biomass and torrefied. During combustion of blends, higher values of relative enrichment factors in fly ash revealed the maximum content of condensing volatile selenium on fly ash particles, and depleted level in bottom ash. Selenium emission in blends decreased by the increasing ratio of both PW and TPW. Higher reductions in the total Se volatilization were found for HAC/TPW than individual HAC sample, recommending that TPW have the best potential of selenium retention. The interaction amongst selenium and fly ash particles may cause the retention of selenium. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative study on direct burning of oil shale and coal

NASA Astrophysics Data System (ADS)

Hammad, Ahmad; Al Asfar, Jamil

2017-07-01

A comparative study of the direct burning processes of oil shale and coal in a circulating fluidized bed (CFB) was done in this study using ANSYS Fluent software to solve numerically the governing equations of continuity, momentum, energy and mass diffusion using finite volume method. The model was built based on an existing experimental combustion burner unit. The model was validated by comparing the theoretical results of oil shale with proved experimental results from the combustion unit. It was found that the temperature contours of the combustion process showed that the adiabatic flame temperature was 1080 K for oil shale compared with 2260 K for coal, while the obtained experimental results of temperatures at various locations of burner during the direct burning of oil shale showed that the maximum temperature reached 962 K for oil shale. These results were used in economic and environmental analysis which show that oil shale may be used as alternative fuel for coal in cement industry in Jordan.

Self-cementitious properties of fly ashes from CFBC boilers co-firing coal and high-sulphur petroleum coke

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

Sheng Guanghong; Li Qin; Zhai Jianping

2007-06-15

Self-cementitious properties of fly ash from circulating fluidized bed combustion boiler co-firing coal and high-sulphur petroleum coke (CPFA) were investigated. CPFA was self-cementitious which was affected by its fineness and chemical compositions, especially the contents of SO{sub 3} and free lime (f-CaO). Higher contents of SO{sub 3} and f-CaO were beneficial to self-cementitious strength; the self-cementitious strength increases with a decrease of its 45 {mu}m sieve residue. The expansive ratio of CPFA hardened paste was high because of generation of ettringite (AFt), which was influenced by its water to binder ratio (W/A), curing style and grinding of the ash. Themore » paste cured in water had the highest expansive ratio, and grinding of CPFA was beneficial to its volume stability. The hydration products of CPFA detected by X-ray diffraction (XRD) and scanning electron microscopy (SEM) were portlandite, gypsum, AFt and hydrated calcium silicate (C-S-H)« less

THE ARMOUR DUST FUELED REACTOR (ADFR). Final Report Covering the Period February 21, 1958 to February 21, 1959

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

Krucoff, D.

1959-10-31

Dust circulation studies were conducted in a 2-in.diam. glass tubing loop, 5 x 5 ft, at gas velocities of 100 and 150 fps. Most of the studies were done with Al/sub 2/O/sub 3/ in air, but some were done with U0/sub 2/2 in N/sub 2/ . Two-group criticality calculations for a graphite-reflected and moderated U/ sup 235/ burner gave approximate values of core size and fuel concentratton. Investigation of axial variations in fuel density indicate that the axial neutron flux and power distributions deviated from the usual cosine distributions, but the effect on critical mass is small. The safety ofmore » the system in the event of large, sudden injections of fuel dust into the core was studied using a simplified model of the gas dynamics. Breeding blanket requirements were examined for a fluidized-bed-type blanket. (See also AECU-3828.) (T.R.H.)« less

Physicochemical characterization and study of in vitro interactions of pH-sensitive liposomes with the complement system.

PubMed

Carmo, Vildete A S; De Oliveira, Mônica C; Reis, Eduardo C O; Guimarães, Tânia M P D; Vilela, José M C; Andrade, Margareth S; Michalick, Marilene S M; Cardoso, Valbert N

2008-01-01

Complement activation is an important step in the acceleration of liposome clearance. The anaphylatoxins released following complement activation may motivate a wide variety of physiologic changes. We performed physicochemical characterization and in vitro studies of the interaction of complement system with both noncirculating and long-circulating pH-sensitive and nonpH-sensitive liposomes. The liposomes were characterized by diameter, zeta potential, and atomic force microscopy (AFM). The study of liposome interactions with complement system was conducted using hemolytic assay in rat serum. All liposomes presented a similar mean diameter (between 99.8 and 124.3 nm). The zeta potential was negative in all liposome preparations, except in liposomes modified with aminopoly (ethyleneglycol) 2000-distearoylphosphatidylethanolamine (aPEG(2000)-DSPE), which presented positive zeta potential. Atomic force microscopy images showed that non-long-circulating pH-sensitive liposomes are prone to vesicles aggregation. Non-pH-sensitive liposomes complement system activates, while pH-sensitive liposomes showed to be poor complement activators in rat serum.

40 CFR 63.7499 - What are the subcategories of boilers and process heaters?

Code of Federal Regulations, 2013 CFR

2013-07-01

... process heaters, as defined in § 63.7575 are: (a) Pulverized coal/solid fossil fuel units. (b) Stokers designed to burn coal/solid fossil fuel. (c) Fluidized bed units designed to burn coal/solid fossil fuel... liquid fuel. (r) Units designed to burn coal/solid fossil fuel. (s) Fluidized bed units with an...

40 CFR 63.7499 - What are the subcategories of boilers and process heaters?

Code of Federal Regulations, 2014 CFR

2014-07-01

... process heaters, as defined in § 63.7575 are: (a) Pulverized coal/solid fossil fuel units. (b) Stokers designed to burn coal/solid fossil fuel. (c) Fluidized bed units designed to burn coal/solid fossil fuel... liquid fuel. (r) Units designed to burn coal/solid fossil fuel. (s) Fluidized bed units with an...

Fluidized-Bed Drying and Storage Stability of Cryptococcus flavescens OH 182.9, a Biocontrol Agent of Fusarium Head Blight

USDA-ARS?s Scientific Manuscript database

A method to produce dried granules of Cryptococcus flavescens (formerly Cryptococcus nodaensis) OH 182.9 was developed and the granules evaluated for storage stability. Small spherical granules were produced and dried using a fluidized bed dryer. A drying and survival curve was produced for the pr...

CIBO special project study: Fluidized bed combustion by-products

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

Soyka, P.A.

1996-12-31

Information is outlined on a Council of Industrial Boiler Owners (CIBO) Special Project Study on fluidized bed combustion by-products. Data are presented on a fossil fuel combustion by-products (FFCB) Survey; study population and response pattern; survey respondent characteristics; FFCB characterization; productive use and impacts; on-site FFCB disposal; and environmental characteristics of FFCB disposal units.

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 ...

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.

Char binder for fluidized beds

DOEpatents

Borio, Richard W.; Accortt, Joseph I.

1981-01-01

An arrangement that utilizes agglomerating coal as a binder to bond coal fines and recycled char into an agglomerate mass that will have suitable retention time when introduced into a fluidized bed 14 for combustion. The simultaneous use of coal for a primary fuel and as a binder effects significant savings in the elimination of non-essential materials and processing steps.

Evaluation of Radial Flow Fluidized Filter (R3F) Followed by Microfiltration and Ultrafiltration Systems in Calimesa, California

EPA Science Inventory

U.S. EPA coordinated a field study with South Mesa Water Utility to look for treatment alternatives for California State Project Water in the small community of Calimesa, California. EPA evaluated the performance of a system comprised of Radial Flow Fluidized Filtration (R3f) fo...

Nitric Oxide Reduction over Sewage Sludge and Coal Chars at Conditions Relevant to Staged Fluidized Bed Combustion

NASA Astrophysics Data System (ADS)

Salatino, P.; Solimene, R.; Chirone, R.

The de-NOx potential of coal and of dried and pelletized sewage sludge, a waste-derived fuel candidate for cofiring with coal, is assessed. The experimental procedure is based on operation of a bench scale fluidized bed reactor where NO-doped nitrogen is contacted with batches of the fuel. A second type of experiment has been purposely designed to assess the loss of reactivity of chars toward gasification by NOx as char is heat-treated for pre-set times at temperatures typical of fluidized bed combustion. A simple phenomenological model is developed to shed light on the basic features of the interaction between heterogeneous char-NOx reaction and thermal annealing of the char.

Fluidized bed gasification of extracted coal

DOEpatents

Aquino, D.C.; DaPrato, P.L.; Gouker, T.R.; Knoer, P.

1984-07-06

Coal or similar carbonaceous solids are extracted by contacting the solids in an extraction zone with an aqueous solution having a pH above 12.0 at a temperature between 65/sup 0/C and 110/sup 0/C for a period of time sufficient to remove bitumens from the coal into said aqueous solution, and the extracted solids are then gasified at an elevated pressure and temperature in a fluidized bed gasification zone (60) wherein the density of the fluidized bed is maintained at a value above 160 kg/m/sup 3/. In a preferred embodiment of the invention, water is removed from the aqueous solution in order to redeposit the extracted bitumens onto the solids prior to the gasification step. 2 figs., 1 tab.

Fluidized muds: a novel setting for the generation of biosphere diversity through geologic time.

PubMed

Aller, J Y; Aller, R C; Kemp, P F; Chistoserdov, A Y; Madrid, V M

2010-06-01

Reworked and fluidized fine-grained deposits in energetic settings are a major modern-day feature of river deltas and estuaries. Similar environments were probably settings for microbial evolution on the early Earth. These sedimentary systems act as efficient biogeochemical reactors with high bacterial phylogenetic diversity and functional redundancy. They are temporally rather than spatially structured, with repeated cycling of redox conditions and successive stages of microbial metabolic processes. Intense reworking of the fluidized bed entrains bacteria from varied habitats providing new, diverse genetic materials to contribute to horizontal gene transfer events and the creation of new bacterial ecotypes. These vast mud environments may act as exporters and promoters of biosphere diversity and novel adaptations, potentially on a globally important scale.

Treatment of TFT-LCD wastewater containing ethanolamine by fluidized-bed Fenton technology.

PubMed

Anotai, Jin; Chen, Chia-Min; Bellotindos, Luzvisminda M; Lu, Ming-Chun

2012-06-01

The objectives of this study are: (1) to determine the effect of pH, initial concentration of Fe(2+) and H(2)O(2) dosage on the removal efficiency of MEA by fluidized-bed Fenton process and Fenton process, (2) to determine the optimal conditions for the degradation of ethanolamine from TFT-LCD wastewater by fluidized-bed Fenton process. In the design of experiment, the Box-Behnken design was used to optimize the operating conditions. A removal efficiency of 98.9% for 5mM MEA was achieved after 2h under optimal conditions of pH3, [Fe(2+)]=5mM and [H(2)O(2)]=60mM. Copyright © 2011 Elsevier Ltd. All rights reserved.

Verification of sub-grid filtered drag models for gas-particle fluidized beds with immersed cylinder arrays

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

Sarkar, Avik; Sun, Xin; Sundaresan, Sankaran

2014-04-23

The accuracy of coarse-grid multiphase CFD simulations of fluidized beds may be improved via the inclusion of filtered constitutive models. In our previous study (Sarkar et al., Chem. Eng. Sci., 104, 399-412), we developed such a set of filtered drag relationships for beds with immersed arrays of cooling tubes. Verification of these filtered drag models is addressed in this work. Predictions from coarse-grid simulations with the sub-grid filtered corrections are compared against accurate, highly-resolved simulations of full-scale turbulent and bubbling fluidized beds. The filtered drag models offer a computationally efficient yet accurate alternative for obtaining macroscopic predictions, but the spatialmore » resolution of meso-scale clustering heterogeneities is sacrificed.« less