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Sample records for liquid-solid circulating fluidized

  1. Biological nutrient removal from leachate using a pilot liquid-solid circulating fluidized bed bioreactor (LSCFB).

    PubMed

    Eldyasti, Ahmed; Chowdhury, Nabin; Nakhla, George; Zhu, Jesse

    2010-09-15

    Biological treatment of landfill leachate is a concern due to toxicity, high ammonia, low biodegradable organic matter concentrations, and low carbon-to-nitrogen ratio. To study the reliability and commercial viability of leachate treatment using an integrated liquid-solid circulating fluidized bed bioreactor (LSCFB), a pilot-scale LSCFB was established at the Adelaide Pollution Control Plant, London, Ontario, Canada. Anoxic and aerobic columns were used to optimize carbon and nutrient removal capability from leachate using 600 microm lava rock with a total porosity of 61%, at empty bed contact times (EBCTs) of 0.55, 0.49, and 0.41 d. The LSCFB achieved COD, nitrogen, and phosphorus removal efficiencies of 85%, 80%, and 70%, respectively at a low carbon-to-nitrogen ratio of 3:1 and nutrients loading rates of 2.15 kg COD/(m(3) d), 0.70 kg N/(m(3) d), and 0.014 kg P/(m(3) d), as compared with 60-77% COD and 70-79% nitrogen removal efficiencies achieved by upflow anaerobic sludge blanket (UASB) and moving bed bioreactor (MBBR), respectively. The LSCFB effluent characterized by

  2. Load maximization of a liquid-solid circulating fluidized bed bioreactor for nitrogen removal from synthetic municipal wastewater.

    PubMed

    Chowdhury, Nabin; Nakhla, George; Zhu, Jesse

    2008-03-01

    A novel liquid-solid circulating fluidized bed bioreactor (LSCFB) configured with anoxic and aerobic columns and lava rock as the biofilm carrier was used to treat synthetic municipal wastewater. Four different empty bed contact times (EBCTs) of 0.82, 0.65, 0.55, and 0.44 h were examined to optimize nutrient removal capability of the system. The LSCFB demonstrated tertiary effluent quality organic and nitrogen removal efficiencies. Effluent characteristics of the LSCFB were soluble biological oxygen demand (SBOD)10 mg l(-1) and total nitrogen (TN)<10 mg l(-1) at organic loading rate (OLR) of 5.3 kg m(-3)d(-1) and nitrogen loading rate of 0.54 kg Nm(-3)d(-1). Remarkably low yields of 0.14, 0.17, 0.19, and 0.21 g VSS g(-1)COD were observed at OLR of 2.6, 3.2, 4.1 and 5.3 kg COD m(-3)d(-1), where increment of biomass growth and detachment rate were also experienced with increasing OLR. However the system demonstrated only 30% phosphorus removal, and mass balances along the anoxic and aerobic columns showed biological phosphorus removal in the system. Organic mass balance showed that approximately 40% of the influent COD was utilized in the anoxic column and the remaining COD was oxidized in the aerobic column. The system is very efficient in nitrification-denitrification, with more than 90% nitrification of ammonium and overall nitrogen removal in the LSCFB was 70+/-11% even at an EBCT of 0.44 h.

  3. Pilot-scale experience with biological nutrient removal and biomass yield reduction in a liquid-solid circulating fluidized bed bioreactor.

    PubMed

    Chowdhury, Nabin; Nakhla, George; Zhu, Jesse; Islam, Mohammad

    2010-01-01

    A pilot-scale liquid-solid circulating fluidized bed (LSCFB) bioreactor was developed at the Adelaide Pollution Control Plant, London, Ontario, Canada, to study its commercial viability for biological nutrient removal. Lava rock particles of 600 microm were used as a biomass carrier media. The LSCFB removed approximately 90% organic, 80% nitrogen, and 70% phosphorus at loading rates of 4.12 kg COD/m3 x d, 0.26 kg N/m3 x d, and 0.052 kg P/m3 x d, and an empty bed contact time of 1.5 hours. Effluent characterized by < 1.0 mg NH4-N/L, < 5.0 mg NO3-N/ L, < 1.0 mg PO4-P/L, < 10 mg TN/L, < 10 mg SBOD/L, and 10 to 15 mg volatile suspended solids (VSS)/L can easily meet the criteria for nonpotable reuse of treated wastewater. The system removed nutrients without using any chemicals, and the secondary clarifier removed suspended solids removal without chemicals. A significant reduction (approximately 75%) in biomass yield to 0.12 to 0.16 g VSS/g chemical oxygen demand (COD) was observed, primarily because of long biological solids retention time (SRT) of 20 to 39 days and a combination of anoxic and aerobic COD consumption.

  4. Photocatalytic degradation of bisphenol A using an integrated system of a new gas-liquid-solid circulating fluidized bed reactor and micrometer Gd-doped TiO2 particles.

    PubMed

    Cheng, Zhiliang; Quan, Xuejun; Xiang, Jinxin; Huang, Yuming; Xu, Yunlan

    2012-01-01

    A new gas-liquid-solid circulating fluidized bed photocatalytic reactor (GLSCFBPR) with internally placed multi-layered UV lamps was developed. Micrometer Gd-TiO2 particles and commercial nanometer P25-TiO2 were chosen as the photocatalysts, and the hazardous substance bisphenol A (BPA) was chosen as the model pollutant to investigate the performance of this new photocatalytic system. The results showed that the photocatalytic degradation efficiency of the micrometer Gd-TiO2 particles was similar to that of the nanometer P-25 particles at their respective optimum dosage but the former could be easily separated out by gravity. After investigating the effects of process parameters on the photocatalytic BPA degradation, the response surface method (RSM) was further used for process optimization. The interactions among process parameters, i.e., TiO2 concentration, superficial gas velocity and superficial liquid velocity were discovered and a related analysis was carried out to explore the underlying mechanism. A quadratic mathematic model was established and performed satisfactorily when used for prediction. The optimum conditions for this new process were as follows: TiO2 concentration 4.5 g/L, superficial gas velocity 7.83 x 10(-3) m/sec and superficial liquid velocity 8.65 x 10(-3) m/sec.

  5. Biological phenol degradation in a gas-liquid-solid fluidized bed reactor

    SciTech Connect

    Wisecarver, K.D.; Fan, L.S.

    1987-01-01

    Biological phenol degradation was performed experimentally in a gas-liquid-solid fluidized bed bioreactor using a mixed culture of living cells immobilized on activated carbon particles. A comprehensive model was developed for this system utilizing double-substrate limiting kinetics. The model was used to simulate the effects of changing inlet phenol concentration and biofilm thickness on the rate of biodegradation for two different types of support particles. The model shows that gas-liquid mass transfer is the limiting step in the rate of phenol biodegradation when the phenol loading is high.

  6. Numerical simulation of flow hydrodynamics of struvite pellets in a liquid-solid fluidized bed.

    PubMed

    Ye, Xin; Chu, Dongyuan; Lou, Yaoyin; Ye, Zhi-Long; Wang, Ming Kuang; Chen, Shaohua

    2017-07-01

    Phosphorus recovery in the form of struvite has been aroused in recent decades for its dual advantages in eutrophication control and resource protection. The usage of the struvite products is normally determined by the size which is largely depended on the hydrodynamics. In this study, flow behavior of struvite pellets was simulated by means of Eulerian-Eulerian two-fluid model combining with kinetic theory of granular flow in a liquid-solid fluidized bed reactor (FBR). A parametric study including the mesh size, time step, discretization strategy, turbulent model and drag model was first developed, followed by the evaluations of crucial operational conditions, particle characteristics and reactor shapes. The results showed that a cold model with the mesh resolution of 16×240, default time step of 0.001sec and first order discretization scheme was accurate enough to describe the fluidization. The struvite holdup profile using Syamlal-O'Brien drag model was best fitted to the experimental data as compared with other drag models and the empirical Richardson-Zaki equation. Regarding the model evaluation, it showed that liquid velocity and particle size played important roles on both solid holdups and velocities. The reactor diameter only influenced the solid velocity while the static bed height almost took no effect. These results are direct and can be applied to guide the operation and process control of the struvite fluidization. Moreover, the model parameters can also be used as the basic settings in further crystallization simulations. Copyright © 2016. Published by Elsevier B.V.

  7. Characterization and modeling of gas-liquid-solid fluidized-bed reactors

    SciTech Connect

    Wisecarver, K.D.

    1987-01-01

    The pressure fluctuation behavior in a 4 inch ID gas-liquid-solid-fluidized bed is studied in this work for a wide variety of particles. The average root mean square of the pressure fluctuations and power spectral density function of the pressure signals are used to characterize the transitions among the various flow regimes. The effect of particle size on the reactant conversion for a pseudo-first order reaction in a catalytic reactor is examined based on a comprehensive model developed in this study. The reactant conversion predicted by the model exhibits a maximum with respect to particle size. Overall reaction rates in the fluidized bed system are compared to those predicted for a slurry bubble column utilizing a sedimentation-dispersion model for the solids. A comprehensive model is presented for biological phenol degradation in a bed containing a mixed culture of immobilized living cells. Double-substrate limiting kinetics and substrate inhibition are considered in the model. Biodegradation rates and phenol and dissolved oxygen concentrations predicted by the model are in excellent agreement with experimental data. The model is used to examine the effects of inlet phenol concentration and biofilm thickness on the biodegradation rate. A mathematical model is also developed for the transient response of a draft tube bioreactor to a step increase in influent phenol concentration. The model considers external mass transfer resistance, the simultaneous diffusion, reaction, and adsorption of phenol and oxygen inside the bioparticles, the dynamics of biofilm growth, the time delay of microbial growth during the transient period, and variations in biofilm thickness and density with biofilm growth.

  8. Characteristics of draft tube gas-liquid-solid fluidized-bed bioreactor with immobilized living cells for phenol degradation

    SciTech Connect

    Fan, L.S.; Fujie, K.; Long, T.R.; Tang, W.T.; Wang, D.I.C.

    1987-09-01

    Biological phenol degradation in a draft tube gas-liquid-solid fluidized bed (DTFB) bioreactor containing a mixed culture immobilized on spherical activated carbon particles was investigated. The characteristics of biofilms including the biofilm dry density and thickness, the volumetric oxygen mass transfer coefficient, and the phenol removal rates under different operating conditions in the DTFB were evaluated. A phenol degradation rate as high as 18 kg/cubic metre/day with an effluent phenol concentration less than 1 g/cubic m was achieved, signifying the high treatment efficiency of using a DTFB. (Refs. 21).

  9. Control of a Circulating Fluidized Bed

    SciTech Connect

    Shim, Hoowang; Rickards, Gretchen; Famouri, Parviz; Turton, Richard; Sams, W. Neal; Koduro, Praveen; Patankar, Amol; Davari, Assad; Lawson, Larry; Boyle, Edward J.

    2001-11-06

    Two methods for optimally controlling the operation of a circulating fluidized bed are being investigated, neural network control and Kalman filter control. The neural network controls the solids circulation rate by adjusting the flow of move air in the non-mechanical valve. Presented is the method of training the neural network from data generated by the circulating fluidized bed (CFB), the results of a sensitivity study indicating that adjusting the move air can control solids flow, and the results of controlling solids circulation rate. The Kalman filter approach uses a dynamic model and a measurement model of the standpipe section of the CFB. Presented are results showing that a Kalman filter can successfully find the standpipe bed height.

  10. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    SciTech Connect

    Not Available

    1992-02-01

    The objective of this DOE Cooperative Agreement is to conduct a cost-shared clean coal technology project to demonstrate the feasibility of circulating fluidized bed combustion technology and to evaluate economic, environmental, and operational benefits of CFB steam generators on a utility scale. At the conclusion of the Phase 2 program, testing related to satisfying these objectives was completed. Data analysis and reporting are scheduled for completion by October 1991. (VC)

  11. Design consideration on fuel flexibility of circulating fluidized bed boilers

    SciTech Connect

    Liu, E.H.; Surabian, M.; Haviland, R.W.

    1986-01-01

    This paper examines the inherent differences between a pulverized coal fired unit and a circulating fluidized bed unit, based on fuel properties, ash properties, and characteristics of combustion and heat transfer to determine generic advantages in fuel flexibility of a circulating fluidized bed combustor. This paper also examines how load control and fuel flexibility may be achieved based on the experience Bechtel gained from the first 650,000 pounds per hour circulating fluidized bed boiler project. The conclusion of this paper addresses the economic merits of having flexibility built in during the design phase of a circulating fluidized bed unit.

  12. Transients in a circulating fluidized bed boiler

    NASA Astrophysics Data System (ADS)

    Baskakov, A. P.; Munts, V. A.; Pavlyuk, E. Yu.

    2013-11-01

    Transients in a circulating fluidized bed boiler firing biomass are considered. An attempt is made to describe transients with the use of concepts applied in the automatic control theory. The parameters calculated from an analysis of unsteady heat balance equations are compared with the experimental data obtained in the 12-MW boiler of the Chalmers University of Technology. It is demonstrated that these equations describe the transient modes of operation with good accuracy. Dependences for calculating the time constants of unsteady processes are obtained.

  13. Nucla circulating atmospheric fluidized bed demonstration project

    SciTech Connect

    Not Available

    1991-01-31

    During the fourth quarter of 1990, steady-state performance testing at the Nucla Circulating Fluidized Bed (CFB) resumed under sponsorship of the US Department of Energy. Co-sponsorship of the Demonstration Test Program by the Electric Power Research Institute (EPRI) was completed on June 15, 1990. From October through December, 1990, Colorado-Ute Electric Association (CUEA) completed a total of 23 steady-state performance tests, 4 dynamic tests, and set operating records during November and December as the result of improved unit operating reliability. Highlight events and achievements during this period of operation are presented.

  14. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    SciTech Connect

    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 plan was completed. (VC)

  15. 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

  16. Nucla circulating atmospheric fluidized bed demonstration project

    SciTech Connect

    Keith, Raymond E.

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute's decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  17. [Structure and fluidization of an internally circulating fluidized bed for FGD process].

    PubMed

    Yang, Liuchun; Yang, Wenqi; Tong, Zhiquan

    2003-09-01

    A new internally circulating fluidized bed for FGD process was developed, and different types of top and bottom structures were employed in the experiment to find out the best fluidized bed structure. Fluidizing status, the axial distribution of solid hold-up and the fluid mechanics under cold conditions were investigated. The results indicate that the unit can realize internally circulating of a large number of solid particles which presents an core-annulus structure when the velocity of fluidizing gas was at the range of 2.5 to 5 m/s, and that the solid density in the bed is higher than that in traditional equal diameter fluidized bed, which provide the equipment with potential for application in FGD process.

  18. COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS

    SciTech Connect

    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 to 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.

  19. Heat transfer in pressurized circulating fluidized beds

    SciTech Connect

    Wirth, K.E.

    1997-12-31

    The wall-to-suspension heat transfer in circulating fluidized beds (CFBs) operated at almost atmospheric pressure depends on the fluid mechanics immediately near the wall and on the thermal properties of the gas used. No influence of the superficial gas velocity adjusted is present. Consequently, the wall-to-suspension heat transfer coefficient in the form of the Nusselt number can be described by the Archimedes number of the gas-solid-system and the pressure drop number. The last number relates the cross-sectional average solids concentration to the solids concentration at minimum fluidization condition. However, with pressurized CFBs an influence of the superficial gas velocity on the wall-to-suspension heat transfer can be observed. Normalizing the superficial gas velocity in the form of the particle Froude number, two cases for the heat transfer in pressurized CFBs can be detected: with small particle Froude numbers (smaller than four) the same flow behavior and consequently the same heat transfer correlation is valid as it is for CFBs operated at almost atmospheric conditions; and with high particle Froude numbers (for example higher than four) the flow behavior immediately near the heat exchanger surface (CFB wall) can change. Instead of curtains of solids falling down with almost atmospheric pressure swirls of gas and solids can occur in the vicinity of the CFB wall when the static pressure is increased. With the change of the flow pattern near the CFB wall, i.e., the heat exchanger surface, a change of the heat transfer coefficient takes place. For the same Archimedes number, i.e., the same gas-solid system, and the same pressure drop number, i.e., the same cross-sectional average solids concentration, the Nusselt number, i.e., the heat transfer coefficient, increases when the flow pattern near the CFB wall changes from the curtain-type flow to that of the swirl-type flow. From experimentally obtained data in a cold running CFB a very simple correlation was

  20. Methods of forming a fluidized bed of circulating particles

    DOEpatents

    Marshall, Douglas W [Blackfoot, ID

    2011-05-24

    There is disclosed an apparatus for forming a fluidized bed of circulating particles. In an embodiment, the apparatus includes a bottom portion having a sidewall, the sidewall defining a curvilinear profile, and the bottom portion configured to contain a bed of particles; and a gas inlet configured to produce a column of gas to carry entrained particles therein. There is disclosed a method of forming a fluidized bed of circulating particles. In an embodiment, the method includes positioning particles within a bottom portion having a sidewall, the sidewall defining a curvilinear profile; producing a column of gas directed upwardly through a gas inlet; carrying entrained particles in the column of gas to produce a fountain of particles over the fluidized bed of circulating particles and subside in the particle bed until being directed inwardly into the column of gas within the curvilinear profile.

  1. Refractory experience in circulating fluidized bed combustors, Task 7

    SciTech Connect

    Vincent, R.Q.

    1989-11-01

    This report describes the results of an investigation into the status of the design and selection of refractory materials for coal-fueled circulating fluidized-bed combustors. The survey concentrated on operating units in the United States manufactured by six different boiler vendors: Babcock and Wilcox, Combustion Engineering, Foster Wheeler, Keeler Dorr-Oliver, Pyropower, and Riley Stoker. Information was obtained from the boiler vendors, refractory suppliers and installers, and the owners/operators of over forty units. This work is in support of DOE's Clean Coal Technology program, which includes circulating fluidized-bed technology as one of the selected concepts being evaluated.

  2. Steam generator with circulating atmospheric fluidized bed combustion

    NASA Astrophysics Data System (ADS)

    Wein, W.; Hoeffgen, H.; Maintok, K. H.; Daradimos, G.

    1982-08-01

    The combustion of coal in power plants by conventional combustion techniques is studied with emphasis on combustion in a circulating atmospheric fluidized bed (CFBC). The CFBC method stays half way between the classical fluidized bed with a well defined bed height and the pneumatic transport where particles and fluidizing gas have the same velocity. The main advantages of CFBC are: flexibility with respect to coal types; easy elimination of 80% of sulfur by mixing the coal with calcium carbonate to a molecular ratio Ca/S of about two; reduced nitrogen oxides production due to the low combustion temperature of 900 C; high steam production efficiency with the combustion degree exceeding 99%; high overall efficiency with no further desulfurizing being needed; easy regulation; high heat transmission rates (350 to 400 W/m2K) reducing exchange surfaces; small boiler building; and the possibility to build in one module a 300 MW unit.

  3. Four Rivers second generation Pressurized Circulating Fluidized Bed Combustion Project

    SciTech Connect

    Holley, E.P.; Lewnard, J.J.; von Wedel, G.; Richardson, K.W.; Morehead, H.T.

    1995-04-01

    Air Products has been selected in the DOE Clean Coal Technology Round V program to build, own, and operate the first commercial power plant using second generation Pressurized Circulating Fluidized Bed (PCFB) combustion technology. The four Rivers Energy Project (Four Rivers) will produce up to 400,000 lb/hr steam, or an equivalent gross capacity of 95 MWe. The unit will be used to repower an Air Products chemicals manufacturing facility in Calvert City, Kentucky.

  4. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project. 1990 Annual report

    SciTech Connect

    Not Available

    1992-02-01

    The objective of this DOE Cooperative Agreement is to conduct a cost-shared clean coal technology project to demonstrate the feasibility of circulating fluidized bed combustion technology and to evaluate economic, environmental, and operational benefits of CFB steam generators on a utility scale. At the conclusion of the Phase 2 program, testing related to satisfying these objectives was completed. Data analysis and reporting are scheduled for completion by October 1991. (VC)

  5. Wall-to-suspension heat transfer in circulating fluidized beds

    SciTech Connect

    Wirth, K.E.

    1995-12-31

    The wall-to-suspension heat transfer in circulating fluidized beds depends on the fluid mechanics immediately near the wall and on the thermal properties of the gas used. Experimental investigations of circulating fluidized beds of low dimensionless pressure gradients with different solid particles like bronze, glass and polystyrene at ambient temperatures showed no influence of the conductivity and the heat capacity of the solids on the heat transfer coefficient. Consequently the heat transfer coefficient in the form of the dimensionless Nusselt number can be described by the dimensionless numbers which characterize the gas-solid-flow near the wall. These numbers are the Archimedes number and the pressure drop-number. The last number relates the cross-sectional average solids concentration to the solids concentration at minimum fluidization condition. With the aid of a model of segregated vertical gas-solid flow, the flow pattern in the wall region can be calculated and thus the wall heat transfer which depends only on heat conduction in the gas and on the convective heat transfer by the gas. With elevated suspension temperatures, radiation contributes additionally to the heat transfer. When the solids concentration is low, the effect of the radiation on the heat transfer is high. Increasing solids concentration results in a decrease of the radiation effect due to the wall being shielded from the radiation of the hot particles in the core region by the cold solids clusters moving down the wall. A simple correlation is presented for calculating the wall-to-suspension heat transfer in circulating fluidized beds.

  6. Dynamic analysis of a circulating fluidized bed riser

    SciTech Connect

    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 solids 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.

  7. Cold-Flow Circulating Fluidized-Bed Identification

    SciTech Connect

    Parviz Famouri

    2005-07-01

    In a variety of industrial applications, the use of a circulating fluidized bed (CFB) provides various advantages, such as reducing environmental pollution and increasing process efficiency. The application of circulating fluidized bed technology contributes to the improvement of gas-solid contact, reduction of the cross-sectional area with the use of higher superficial velocities, the use of the solids circulation rate as an additional control variable, and superior radial mixing, Grace et al. [1]. In order to improve raw material usage and utility consumption, optimization and control of CFB is very important, and an accurate, real time model is required to describe and quantify the process. Currently there is no accepted way to construct a reliable model for such a complex CFB system using traditional methods, especially at the pilot or industrial scale. Three major obstacles in characterizing the system are: 1) chaotic nature of the system; 2) non-linearity of the system, and 3) number of immeasurable unknowns internal to the system,[2]. Advanced control theories and methods have the ability to characterize the system, and can overcome all three of these obstacles. These methods will be discussed in this report.

  8. Four Rivers second generation pressurized circulating fluidized bed combustion project

    SciTech Connect

    Holley, E.P.; Lewnard, J.J.; Wedel, G. von; Richardson, K.W.; Morehead, H.T.

    1995-12-31

    Air Products has been selected in the DOE Clean Coal Technology Round 5 program to build, own, and operate the first commercial power plant using second generation Pressurized Circulating Fluidized Bed (PCFB) combustion technology. The Four Rivers Energy Project (Four Rivers) will produce approximately 70 MW electricity, and will produce up to 400,000 lb/hr steam, or an equivalent gross capacity of 95 MWe. The unit will be used to repower an Air Products chemicals manufacturing facility in Calvert City, Kentucky.

  9. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project. Annual report, 1988

    SciTech Connect

    Not Available

    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 plan was completed. (VC)

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

    SciTech Connect

    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 the 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.

  11. Heat-transfer characteristics in viscous gas-liquid and gas-liquid-solid systems

    SciTech Connect

    Kumar, S.; Fan, L.S. . Dept. of Chemical Engineering)

    1994-05-01

    Local heat-transfer measurements are performed using a special heat-transfer probe in gas-liquid and gas-liquid-solid systems with viscous Newtonian liquids as the continuous phase. Effects of viscosity on bubble-liquid and bubble-liquid-solid interactions affecting local heat transfer are studied through heat-transfer experiments with simultaneous flow visualization in a simplified system involving single bubbles or a chain of gas bubbles moving in viscous liquids and liquid-solid systems. Effects of viscosity on bubble wake and local heat transfer are examined with reference to heat transfer in freely-bubbling beds (bubble columns and three-phase fluidized beds). The kinematic viscosity of the fluid greatly influences the nature of flow in the wake which affects local heat transfer in the bed. The local heat transfer decreases with the viscosity due to the rapid decay in the circulation strength of the bubble wake caused by increased viscous dissipation of vorticity. Local heat transfer due to cyclic/periodic injection of bubbles is significantly enhanced due to increased bubble-wake interactions which rapidly accelerate bubbles and increase average bubble rise velocity. Heat transfer in simplified liquid and liquid-solid systems with single- and chain-bubble injections characterizes the local heat-transfer performance of freely-bubbling beds (bubble columns and three-phase fluidized beds). A mechanistic model developed accounts for the heat-transfer behavior in bubble columns and three-phase fluidized beds with viscous liquids.

  12. Specification considerations for a circulating fluidized bed boiler

    SciTech Connect

    Liu, E.H.; Surabian, M. )

    1988-01-01

    The circulating fluidized bed (CFB) boiler is gradually gaining acceptance in both the industrial and utility sectors for electric power generation. Boiler steaming capacity in CFBs has increased to over a million pounds per hour in the most recent units. Many CFB units commisioned during the last few years worldwide have had difficult and extended start-up periods, but this experience has provided a good base of feedback for future units. There has been widespread use of the same criteria for a conventional pulverized coal or stoker boiler to specify the CFB boiler. This paper examines the unique design aspects of a CFB boiler and provides suggestions in the areas where specific requirements should be included in the specification of the boiler and its related systems. Areas examined include fuel handling area, burner systems, the combustor, cyclone and solids recirculation equipment, convention pass, the design and installation of refractories, fans and blowers, bed ash removal system, and particulate control equipment.

  13. Oxy-combustion of biomass in a circulating fluidized bed

    NASA Astrophysics Data System (ADS)

    Kosowska-Golachowska, Monika; Kijo-Kleczkowska, Agnieszka; Luckos, Adam; Wolski, Krzysztof; Musiał, Tomasz

    2016-03-01

    The objective of this study was to investigate combustion characteristics of biomass (willow, Salix viminalis) burnt in air and O2/CO2 mixtures in a circulating fluidized bed (CFB). Air and oxy-combustion characteristics of wooden biomass in CFB were supplemented by the thermogravimetric and differential thermal analyses (TGA/DTA). The results of conducted CFB and TGA tests show that the composition of the oxidizing atmosphere strongly influences the combustion process of biomass fuels. Replacing N2 in the combustion environment by CO2 caused slight delay (higher ignition temperature and lower maximum mass loss rate) in the combustion of wooden biomass. The combustion process in O2/CO2 mixtures at 30% and 40% O2 is faster and shorter than that at lower O2 concentrations.

  14. Nucla circulating atmospheric fluidized bed demonstration project. Final report

    SciTech Connect

    Not Available

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute`s decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  15. 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.

  16. Integrated drying and incineration of wet sewage sludge in combined bubbling and circulating fluidized bed units.

    PubMed

    Li, Shiyuan; Li, Yunyu; Lu, Qinggang; Zhu, Jianguo; Yao, Yao; Bao, Shaolin

    2014-12-01

    An original integrated drying and incineration technique is proposed to dispose of sewage sludge with moisture content of about 80% in a circulating fluidized bed. This system combines a bubbling fluidized bed dryer with a circulating fluidized bed incinerator. After drying, sewage sludge with moisture less than 20% is transported directly and continuously from the fluidized bed dryer into a circulating fluidized bed incinerator. Pilot plant results showed that integrated drying and incineration is feasible in a unique single system. A 100 t/d Sewage Sludge Incineration Demonstration Project was constructed at the Qige sewage treatment plant in Hangzhou City in China. The operational performance showed that the main operation results conformed to the design values, from which it can be concluded that the scale-up of this technique is deemed both feasible and successful. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Some features of the technology for thermochemical reprocessing of coals in a circulating fluidized bed

    NASA Astrophysics Data System (ADS)

    Rokhman, B. B.

    2007-06-01

    Results from theoretical investigations into transfer processes during the combustion of anthracite culm in a circulating fluidized bed furnace are presented. A method is described according to which hot air is separately admitted into the furnace: the primary air, to under the fluidized-bed grate, and the secondary air, to over its upper boundary. Calculation results together with their discussion are presented.

  18. Circulating fluidized-bed boiler makes inroads for waste recycling

    SciTech Connect

    1995-09-01

    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 removed 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.

  19. Modeling of devolatilization in circulating fluidized bed combustion

    SciTech Connect

    Stenseng, M.; Lin, W.; Johnsson, J.E.; Dam-Johansen, K.

    1997-12-31

    A mathematical model is developed to describe the devolatilization process in a circulating fluidized bed combustor. The model is a combination of two submodels: single particle devolatilization and fluid dynamics. The single particle model includes the influence of both chemical kinetics and heat transfer on the rate of devolatilization. The results show a good agreement with literature data. The fluid dynamic model describes the main characteristics of a CFB: a dense zone in the bottom, followed by a splash zone and a dilute zone with a core-annulus structure. Each zone is modeled as a number of CSTR`s and the size and number of CSTR`s has been estimated from tracer experiments in an 80 MW{sub th} CFB boiler. It was not possible to evaluate the model against experimental data, but the dependence of particle size on the degree of devolatilization in the dense bed agrees qualitative with the expected behavior. The mode4l shows that the devolatilization mainly occurs in the dense bed.

  20. Heavy metal characterization of circulating fluidized bed derived biomass ash.

    PubMed

    Li, Lianming; Yu, Chunjiang; Bai, Jisong; Wang, Qinhui; Luo, Zhongyang

    2012-09-30

    Although the direct combustion of biomass for energy that applies circulating fluidized bed (CFB) technology is steadily expanding worldwide, only few studies have conducted an environmental assessment of biomass ash thus far. Therefore, this study aims to integrate information on the environmental effects of biomass ash. We investigated the concentration of heavy metal in biomass ash samples (bottom ash, cyclone ash, and filter ash) derived from a CFB boiler that combusted agricultural and forest residues at a biomass power plant (2×12 MW) in China. Ash samples were gathered for the digestion and leaching test. The heavy metal content in the solution and the leachate was studied via an inductively coupled plasma-mass spectrometer and a Malvern Mastersizer 2000 mercury analyzer. Measurements for the chemical composition, particle size distribution, and the surface morphology were carried out. Most of the metals in cyclone ash particles were enriched, whereas Ti and Hg were enriched in filter ash. Residence time contributed most to heavy metal enrichment. Under HJ/T 300 conditions, the heavy metals showed serious leaching characteristics. Under EN 12457-2 conditions, leaching behavior was hardly detected.

  1. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Unknown

    2001-07-10

    Foster Wheeler Development Corporation is working under DOE contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% while producing near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The unique aspect of the process is that it utilizes a pressurized circulating fluidized bed partial gasifier and does not attempt to consume the coal in a single step. To convert all the coal to syngas in a single step requires extremely high temperatures ({approx}2500 to 2800F) that melt and vaporize the coal and essentially drive all coal ash contaminants into the syngas. Since these contaminants can be corrosive to power generating equipment, the syngas must be cooled to near room temperature to enable a series of chemical processes to clean the syngas. Foster Wheeler's process operates at much lower temperatures that control/minimize the release of contaminants; this eliminates/minimizes the need for the expensive, complicated syngas heat exchangers and chemical cleanup systems typical of high temperature gasification. By performing the gasification in a circulating bed, a significant amount of syngas can still be produced despite the reduced temperature and the circulating bed allows easy scale up to large size plants. Rather than air, it can also operate with oxygen to facilitate

  2. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Unknown

    2002-03-29

    Foster Wheeler Development Corporation is working under DOE contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% while producing near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The unique aspect of the process is that it utilizes a pressurized circulating fluidized bed partial gasifier and does not attempt to consume the coal in a single step. To convert all the coal to syngas in a single step requires extremely high temperatures ({approx}2500 to 2800 F) that melt and vaporize the coal and essentially drive all coal ash contaminants into the syngas. Since these contaminants can be corrosive to power generating equipment, the syngas must be cooled to near room temperature to enable a series of chemical processes to clean the syngas. Foster Wheeler's process operates at much lower temperatures that control/minimize the release of contaminants; this eliminates/minimizes the need for the expensive, complicated syngas heat exchangers and chemical cleanup systems typical of high temperature gasification. By performing the gasification in a circulating bed, a significant amount of syngas can still be produced despite the reduced temperature and the circulating bed allows easy scale up to large size plants. Rather than air, it can also operate with oxygen to facilitate

  3. Utilization of ventilation air methane as a supplementary fuel at a circulating fluidized bed combustion boiler.

    PubMed

    You, Changfu; Xu, Xuchang

    2008-04-01

    Ventilation air methane (VAM) accounts for 60-80% of the total emissions from coal mining activities in China, which is of serious greenhouse gas concerns as well as a waste of valuable fuel sources. This contribution evaluates the use of the VAM utilization methods as a supplementary fuel at a circulating fluidized bed combustion boiler. The paper describes the system design and discusses some potential technical challenges such as methane oxidation rate, corrosion, and efficiency. Laboratory experimentation has shown that the VAM can be burnt completely in circulated fluidized bed furnaces, and the VAM oxidation does not obviously affect the boiler operation when the methane concentration is less than 0.6%. The VAM decreased the incomplete combustion loss for the circulating fluidized bed combustion furnace. The economic benefit from the coal saving insures that the proposed system is more economically feasible.

  4. Refractory experience in circulating fluidized bed combustors, Task 7. Final report

    SciTech Connect

    Vincent, R.Q.

    1989-11-01

    This report describes the results of an investigation into the status of the design and selection of refractory materials for coal-fueled circulating fluidized-bed combustors. The survey concentrated on operating units in the United States manufactured by six different boiler vendors: Babcock and Wilcox, Combustion Engineering, Foster Wheeler, Keeler Dorr-Oliver, Pyropower, and Riley Stoker. Information was obtained from the boiler vendors, refractory suppliers and installers, and the owners/operators of over forty units. This work is in support of DOE`s Clean Coal Technology program, which includes circulating fluidized-bed technology as one of the selected concepts being evaluated.

  5. 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.

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

    SciTech Connect

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

    2005-01-30

    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. 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.

  7. Optimization of Solid Circulation Rate in Compartmented Fluidized Bed Gasifier for Power Generation

    NASA Astrophysics Data System (ADS)

    Chok, V. S.; Wee, S. K.; Ariffin, M. Z. Mohd.; Gorin, A.; Chua, H. B.; Yan, H. M.

    2008-10-01

    The present paper reports the optimization of solid circulation rate (SCR) in Compartmented Fluidized Bed Gasifier (CFBG), an indirectly heated fluidized bed that incorporates two sets of v-valves and risers to control the solid circulation across the two compartments, i.e. combustor and gasifier of a pilot plant scale (the height and ID are 1.8m and 0.66m respectively). Sand was used as inert fluidized by air. Four operating variables were studied i.e. bed height, riser, v-valve and main bed flowrate. Based on 24 full factorial design of experiment in Yates' algorithm, at confidence level ⩾95%, ANOVA analysis has revealed six important effects. The steepest ascent method was applied on linear regression generated from these effects to design the subsequent optimization experiments. The optimum values of SCR have been estimated for both low and high bed level at specific operating parameters.

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

    SciTech Connect

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

    2004-10-30

    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 July 1, 2004 through September 30, 2004. The following tasks have been completed. First, renovation of the new Combustion Laboratory and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building have started. Second, the design if the component parts of the CFBC system have been reviewed and finalized so that the drawings may be released to the manufacturers during the next quarter. Third, the experiments for solid waste (chicken litter) incineration have been conducted using a Thermogravimetric Analyzer (TGA). This is in preparation for testing in the simulated fluidized-bed combustor. 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.

  9. Optimization of circulating fluidized bed boiler operation through distributed control system design management

    SciTech Connect

    Swartz, M.; Utt, J. )

    1990-01-01

    The introduction of the circulating fluidized bed (CFB) technology to the boiler industry has also introduced some new considerations and unique criteria for design of the plant control system. The topics concerning selection, design, configuration, and operation of the control system for CFB applications are discussed.

  10. A MODEL FOR FINE PARTICLE AGGLOMERATION IN CIRCULATING FLUIDIZED BED ABSORBERS

    EPA Science Inventory

    A model for fine particle agglomeration in circulating fluidized bed absorbers (CFBAS) has been developed. It can model the influence of different factors on agglomeration, such as the geometry of CFBAs, superficial gas velocity, initial particle size distribution, and type of ag...

  11. Applications of kinetic theory. Predictive models of circulating fluidized bed combustors: Tenth technical progress report

    SciTech Connect

    Gidaspow, D.

    1992-01-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. This report presents the author`s derivation of analytical solutions useful in understanding the operation of a CFB. The report is in a form of a chapter that reviews the kinetic theory applications.

  12. A MODEL FOR FINE PARTICLE AGGLOMERATION IN CIRCULATING FLUIDIZED BED ABSORBERS

    EPA Science Inventory

    A model for fine particle agglomeration in circulating fluidized bed absorbers (CFBAS) has been developed. It can model the influence of different factors on agglomeration, such as the geometry of CFBAs, superficial gas velocity, initial particle size distribution, and type of ag...

  13. Controlling thermal properties of dense gas fluidized beds for concentrated solar power by internal and external solids circulation

    NASA Astrophysics Data System (ADS)

    Ammendola, Paola; Bareschino, Piero; Chirone, Riccardo; Salatino, Piero; Solimene, Roberto

    2017-06-01

    Fluidization technology displays a long record of success stories, mostly related to applications to thermal and thermochemical processes, which are fostering extension to novel and relatively unexplored fields. Application of fluidized beds to collection and thermal storage of solar radiation in Concentrated Solar Power (CSP) is one of the most promising, a field which poses challenging issues and great opportunities to fluidization scientists and technologists. The potential of this growing field calls for reconsideration of some of the typical design and operation guidelines and criteria, with the goal of exploiting the inherently good thermal performances of gas-fluidized beds at their best. "Creative" and non-conventional design and operation of fluidized beds, like those based on internal and external solids circulation, may be beneficial to the enhancement of thermal diffusivity and surface-to-bed heat transfer, improving the potential for application in the very demanding context of CSP with thermal energy storage. This paper investigated: i) a fluidized bed configuration with an uneven distribution of the fluidizing gas to promote vortices in the scale of bed height (internal solids circulation); ii) a dual fluidized bed configuration characterized by an external solids circulation achieved by the operation of a riser and a bubbling fluidized bed. CFD simulations showed the hydrodynamics conditions under which the internal solids circulation was established. The hydrodynamic characterization of the external solids circulation was achieved by an experimental study carried out with different cold models. The dual fluidized bed system was optimized in terms of operating conditions and geometrical features of the connections between two fluidized beds.

  14. Results of theoretical and experimental studies of hydrodynamics of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors

    NASA Astrophysics Data System (ADS)

    Ryabov, G. A.; Folomeev, O. M.; Sankin, D. A.; Melnikov, D. A.

    2015-02-01

    Problems of the calculation of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors (polygeneration systems for the production of electricity, heat, and useful products and chemical cycles of combustion and gasification of solid fuels)are considered. A method has been developed for the calculation of circulation loop of fuel particles with respect to boilers with circulating fluidized bed (CFB) and systems with interconnected reactors with fluidized bed (FB) and CFB. New dependences for the connection between the fluidizing agent flow (air, gas, and steam) and performance of reactors and for the whole system (solids flow rate, furnace and cyclone pressure drops, and bed level in the riser) are important elements of this method. Experimental studies of hydrodynamics of circulation loops on the aerodynamic unit have been conducted. Experimental values of pressure drop of the horizontal part of the L-valve, which satisfy the calculated dependence, have been obtained.

  15. Desulfurization Characteristics of Fly Ash Recirculation and Combustion in the Circulating Fluidized Bed Boiler

    NASA Astrophysics Data System (ADS)

    Li, S. F.; Fang, M. X.; Yu, B.; Wang, Q. H.; Luo, Z. Y.

    The experiments of the fly ash recycle combustion using Guizhou anthracite were carried out in a bench scale circulating fluidized bed (CFB) combustor. Effects of some key operating parameters such as recycle ash to coal mass ratio (Ca to S molar ratio), temperature, reactivation modeof fly ash, circulation rateand fluidization velocity on the desulfurization efficiency were intensively investigated. It is shown that thelimestone utilization efficiency could be improved about 30% with the following operating conditions: the mass ratio of fly ash (reactivated by water and dried at 90°C) to coal was 0.45, the furnace temperature was 880°C, the water to ash mass ratio was 4.5% (the water-to-calcium molar ratio was 0.55) and circulation rate was 18.

  16. Cleaning and Heat Transfer in Heat Exchanger with Circulating Fluidized Beds

    NASA Astrophysics Data System (ADS)

    Kang, Ho Keun; Ahn, Soo Whan; Choi, Jong Woong; Lee, Byung Chang

    2010-06-01

    Fluidized bed type heat exchangers are known to increase the heat transfer and prevent the fouling. For proper design of circulating fluidized bed heat exchanger it is important to know the effect of design and operating parameters on the bed to the wall heat transfer coefficient. The present experimental and numerical study was conducted to investigate the effects of circulating solid particles on the characteristics of fluid flow, heat transfer and cleaning effect in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which a variety of solid particles such as glass (3 mmF), aluminum (2˜3 mmF), steel (2˜2.5 mmF), copper (2.5 mmF) and sand (2˜4 mmF) were used in the fluidized bed with a smooth tube. Seven different solid particles have the same volume, and the effects of various parameters such as water flow rates, particle diameter, materials and geometry were investigated. The present experimental and numerical results showed that the flow velocity range for collision of particles to the tube wall was higher with heavier density solid particles, and the increase in heat transfer was in the order of sand, copper, steel, aluminum, and glass. This behaviour might be attributed to the parameters such as surface roughness or particle heat capacity. Fouling examination using 25,500 ppm of ferric oxide (Fe2O3) revealed that the tube inside wall is cleaned by a mild and continuous scouring action of fluidized solid particles. The fluidized solid particles not only keep the surface clean, but they also break up the boundary layer improving the heat transfer coefficient even at low fluid velocities.

  17. Postcombustion Capture of CO2 with CaO in a Circulating Fluidized Bed Carbonator

    NASA Astrophysics Data System (ADS)

    Alonso, M.; Rodriguez, N.; González, B.; Grasa, G.; Murillo, R.; Abanades, J. C.

    There is an emerging postcombustion capture technology that uses CaO to capture CO2 from combustion flue gases in a circulating fluidized bed reactor. This paper summarizes recent work conducted at CSIC to understand and develop this technology. The paper includes experimental results at conditions close to those expected in the real system, carried out in continuous mode in a 30kW test facility made up of two interconnected circulating fluidized bed reactors. In one of the reactors, CO2 is captured from the gas phase by the CaO continuously circulating from a calciner. In the second reactor, the CaCO3 formed in the carbonator is regenerated to CaO and CO2 by calcination. Modeling of the system at process level, at reactor level (in particular the CFB carbonator), and at particle level (decay in capture capability of CaO) is also outlined. The work carried out so far confirms that the carbonator reactors can be designed to attain capture efficiencies between 70-90%, operating at fluid dynamic conditions close to those present in circulating fluidized bed combustors.

  18. Coal and biomass co-combustion on fluidized bed: Comparison of circulating and bubbling fluidized bed technologies

    SciTech Connect

    Armesto, L.; Cabanillas, A.; Bahillo, A.; Segovia, J.J.; Escalada, R.; Martinez, J.M.; Carrasco, J.E.

    1997-12-31

    The main objective of the proposed paper is to demonstrate the technical feasibility of fluidized bed as a clean technology for the combustion of low grade coal/biomass blends. The raw materials used as fuels in the tests are different blends of the following materials: refuse coal with a heating value of 3,658 kJ/kg (LHV, db) and 79.65% ash content; low grade coal--lignite with a heating value of 19952 kJ/kg (LHV, db), a sulfur content of 10.32% (db) and 23.70% ash content; and biomass--forestry wastes from wood cleaning whose heating value is 19555 kJ/kg (LHV, db). An absorbent, limestone, has been used for reducing sulfur emissions. Co-combustion tests, at the pilot plant level, have been carried out by using two fluidized bed technologies, circulating and bubbling. The object of this paper is to study, in an energy and emission point of view, the clean and efficient use of these resources. The paper collects, analyses and compares combustion test data.

  19. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    SciTech Connect

    Wei-Ping Pan; Yan Cao; Songgeng Li

    2006-04-01

    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 January 1, 2006 through March 31, 2006. Work was performed on the following activities. First, the fabrication and manufacture of the CFBC Facility were completed. The riser, primary cyclone and secondary cyclone of Circulating Fluidized Bed (CFB) Combustor have been erected. Second, the Mercury Control Workshop and the Grand Opening of Institute for Combustion Science and Environmental Technology (ICSET) were successfully held on February 22 and 23, 2006, respectively. Third, effects of hydrogen chlorine (HCl) and sulfur dioxide (SO{sub 2}) on mercury oxidation were studied in a drop tube reactor. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described in this report.

  20. Technology evaluation for a waste-fuel-based circulating fluidized-bed project

    SciTech Connect

    Kavidass, S.

    1994-12-31

    A comparative technology evaluation is made of competing technologies - pulverized coal (PC), stoker-fired and circulating fluidized-bed boilers - for firing high-ash waste coal. Operating experience from Ukraine and India indicates that PC-fired boilers burning high-ash waste coal can be repowered with circulating fluidized-bed (CFB) technology. This has been necessary due to poor boiler availability, equipment deterioration, ash content variation in the fuel, and increasingly stringent emissions regulations. Due to these considerations, CFB technology was selected for Ebensburg Power Company`s high-ash waste coal project. The 55 MW B&W CFB boiler at Ebensburg Power, Pennsylvania, USA has successfully fired high-ash waste coal since May 1991. Operating experience of the Ebensburg CFB boiler, including availability, maintenance, and emissions is discussed.

  1. 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.

  2. Prediction of Solids Circulation Rate of Cork Particles in an Ambient-Pressure Pilot-Scale Circulating Fluidized Bed

    SciTech Connect

    Huang, Yue; Turton, Richard; Famouri, Parviz; Boyle, Edward J.

    2009-01-07

    Circulating fluidized beds (CFB) are currently used in many industrial processes for noncatalytic and catalytic because its effective control is the key to smooth operation of a CFB system. This paper presents a method for solids flow metering from pressure drop measurements in the standpipe dense phase. A model based on the Ergun equation is developed to predict the solids flow rate and voidage in the dense phase of the standpipe. The profile of the solids flow rate under unsteady state is also presented. With the use of this method, the dynamic response time at different locations along the standpipe of a pilot-scale fluidized bed operating at ambient conditions with 812 mu m cork particles is estimated successfully. Through the use of a pressure balance analysis, solids flow models for the standpipe, riser, and other sections of the flow loop are combined to give an integrated CFB model.

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

    SciTech Connect

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

    2005-07-30

    This purpose of 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 April 1, 2005 through June 30, 2005. The following tasks have been completed. First, the new Combustion Laboratory was occupied on June 15, 2005, and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building is in the final painting stage. Second, the fabrication and manufacturing contract for the CFBC Facility was awarded to Sterling Boiler & Mechanical, Inc. of Evansville, Indiana. Sterling is manufacturing the assembly and component parts of the CFBC system. The erection of the CFBC system is expected to start September 1, 2005. Third, mercury emissions from the cofiring of coal and chicken waste was studied experimentally in the laboratory-scale simulated fluidized-bed combustion facility. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described.

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

    SciTech Connect

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

    2005-04-30

    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 January 1, 2005 through March 31, 2005. The following tasks have been completed. First, the renovation of the new Combustion Laboratory is nearly complete, and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building is in the final stages. Second, the fabrication and manufacture of the CFBC Facility is being discussed with a potential contractor. Discussions with potential contactor regarding the availability of materials and current machining capabilities have resulted in the modification of the original designs. The selection of the fabrication contractor for the CFBC Facility is expected during the next quarter. Third, co-firing experiments conducted with coal and chicken waste have been initiated in the laboratory-scale simulated fluidized-bed facility. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described in this report.

  5. MFIX simulation of NETL/PSRI challenge problem of circulating fluidized bed

    SciTech Connect

    Li, Tingwen; Dietiker, Jean-François; Shahnam, Mehrdad

    2012-12-01

    In this paper, numerical simulations of NETL/PSRI challenge problem of circulating fluidized bed (CFB) using the open-source code Multiphase Flow with Interphase eXchange (MFIX) are reported. Two rounds of simulation results are reported including the first-round blind test and the second-round modeling refinement. Three-dimensional high fidelity simulations are conducted to model a 12-inch diameter pilot-scale CFB riser. Detailed comparisons between numerical results and experimental data are made with respect to axial pressure gradient profile, radial profiles of solids velocity and solids mass flux along different radial directions at various elevations for operating conditions covering different fluidization regimes. Overall, the numerical results show that CFD can predict the complex gas–solids flow behavior in the CFB riser reasonably well. In addition, lessons learnt from modeling this challenge problem are presented.

  6. Development of Catalytic Tar Decomposition in an Internally Circulating Fluidized-Bed Gasifier

    NASA Astrophysics Data System (ADS)

    Xiao, Xianbin; Le, Due Dung; Morishita, Kayoko; Li, Liuyun; Takarada, Takayuki

    Biomass gasification in an Internally Circulating Fluidized-bed Gasifier (ICFG) using Ni/Ah03 as tar cracking catalyst is studied at low temperature. Reaction conditions of the catalyst bed are discussed, including catalytic temperature and steam ratio. High energy efficiency and hydrogen-rich, low-tar product gas can be achieved in a properly designed multi-stage gasification process, together with high-performance catalyst. In addition, considering the economical feasibility, a newly-developed Ni-loaded brown coal char is developed and evaluated as catalyst in a lab-scale fluidized bed gasifier with catalyst fixed bed. The new catalyst shows a good ability and a hopeful prospect oftar decomposition, gas quality improvement and catalytic stability.

  7. MFIX simulation of NETL/PSRI challenge problem of circulating fluidized bed

    DOE PAGES

    Li, Tingwen; Dietiker, Jean-François; Shahnam, Mehrdad

    2012-12-01

    In this paper, numerical simulations of NETL/PSRI challenge problem of circulating fluidized bed (CFB) using the open-source code Multiphase Flow with Interphase eXchange (MFIX) are reported. Two rounds of simulation results are reported including the first-round blind test and the second-round modeling refinement. Three-dimensional high fidelity simulations are conducted to model a 12-inch diameter pilot-scale CFB riser. Detailed comparisons between numerical results and experimental data are made with respect to axial pressure gradient profile, radial profiles of solids velocity and solids mass flux along different radial directions at various elevations for operating conditions covering different fluidization regimes. Overall, the numericalmore » results show that CFD can predict the complex gas–solids flow behavior in the CFB riser reasonably well. In addition, lessons learnt from modeling this challenge problem are presented.« less

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

    SciTech Connect

    Wei-Ping Pan; Kunlei Liu; John T. Riley

    2004-01-01

    The purpose of this report is to summarize the progress made on the project ''Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion (CFBC) System'' in this quarter (September-December of 2003). The main tasks in this quarter consisted of the following four parts. First, all documents for managing this project have been prepared and sent to the Office of Project Management at the US Department of Energy's (DOE's) National Energy Technology Laboratory (NETL). Second, plans for the renovation of space for a new combustion laboratory for the CFBC system has progressed smoothly. Third, considerable progress in the design of the CFBC system has been made. Finally, a lab-scale simulated fluidized-bed combustion facility has been set up in order to make some fundamental investigations of the co-firing of coal with waste materials in the next quarter. Proposed work for the next quarter has been outlined in this report.

  9. Air-based coal gasification in a two-chamber gas reactor with circulating fluidized bed

    NASA Astrophysics Data System (ADS)

    Dubinin, A. M.; Tuponogov, V. G.; Kagramanov, Y. A.

    2017-01-01

    During the bed gasification of solid fuels, the process temperature in the reaction zone is not high enough for reaching the maximum rate of the chemical efficiency factor of the gasification process. In order to increase the chemical efficiency factor, it is necessary to supply extra heat to the reaction zone to increase the reaction temperature. In this article, coal gasification in a chamber with forced fluidized bed is considered and it is proposed to supply extra heat with a circulating flow of an inert particulate heat transfer agent. Circulating inert particulate material is successively heated by coal combustion in a cone chamber with bubbling fluidized bed and in a combustion chamber with a spherical nozzle that inhibits the forced fluidized bed. After that, the heat transfer agent heated to 930-950°C enters first in a gasification chamber with bubbling bed and then in a chamber with forced fluidized bed, where it transfers the physical heat to the air fuel mixture. The experiments conducted with crushed Borodinsky coal and inert particulate heat transfer agent (electrocorundum) showed the temperature rise in a gasification chamber with from 760 to 870°C and the increase in the combustible component (CO) concentration in the gasification products by 5.5%. Based on the kinetic equations of the fuel combustion reactions and the CO2 reduction to CO and on the thermal balance equations of combustion and gasification chambers, the simulation model for the gas composition and the temperature rate calculated by the height of reaction chambers was developed. The experimental temperature rates and product gas compositions are in good agreement with the simulation results based on the proposed kinetic gasification model.

  10. Standpipe models for diagnostics and control of a circulating fluidized bed

    SciTech Connect

    Ludlow, James C.; Panday, Rupen

    2013-01-01

    Two models for a Circulating Fluidized Bed (CFB) standpipe were formulated, implemented and validated to estimate critical CFB operational parameters. The first model continuously estimates standpipe bed height using incremental pressure measurements within the standpipe. The second model estimates variations in the void fraction along the standpipe using the Ergun equation in conjunction with the overall pressure drop across the bed, solids circulation rate and the standpipe aeration flows introduced at different locations of the pipe. The importance of different standpipe parameters obtained from these models is discussed in terms of successful operation of the overall CFB system. Finally, the applications of these models are shown in improving the solids circulation rate measurement and in calculating riser inventory.

  11. Evaluation of biological nutrient removal from wastewater by Twin Circulating Fluidized Bed Bioreactor (TCFBBR) using a predictive fluidization model and AQUIFAS APP.

    PubMed

    Andalib, Mehran; Nakhla, George; Sen, Dipankar; Zhu, Jesse

    2011-02-01

    A two-phase and three-phase predictive fluidization model based on the characteristics of a system such as media type and size, flow rates, and reactor cross sectional area was proposed to calculate bed expansion, solid, liquid and gas hold up and specific surface area (SSA) of the biofilm particles. The model was subsequently linked to 1d AQUIFAS APP software (Aquaregen) to model biological nutrient removal in two phase (anoxic) and three phase (aerobic) fluidized bed bioreactors. The credibility of the proposed model for biological nutrient removal was investigated using the experimental data from a Twin Circulating Fluidized Bed Bioreactors (TCFBBR) treating synthetic and municipal wastewater. The SSA of bio-particles and volume of the expanded bed were simulated as a function of operational parameters. Two-sided t-tests demonstrated that simulated SCOD, NH(4)-N, NO(3)-N, TN, VSS and biomass yields agreed with the experimental values at the 95% confidence level.

  12. 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.

  13. 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.

  14. Design and performance of a circulating fluidized bed boiler firing stone coal

    SciTech Connect

    Luo Zhongyang; Li Xuantian; Fang Mengxiang; Luo Chuanqui; Cen Kefa; Ni Mingjiang; Cheng Leming

    1995-12-31

    The design and performance of a demonstrating 35 T/H circulating fluidized bed boiler firing stone coal are reported. The boiler features low recycle rate, unique downward gas exit cyclones in the medium temperature region between the superheater and the economizer to reduce the size of the cyclone separators, and to allow a more compact reversed U general arrangement. Based on computer-aided testing, some different anti-erosion components are employed to maintain acceptable lifetime of the heating surfaces. The boiler demonstrates high combustion efficiency and low emissions with staged combustion.

  15. Nucla circulating atmospheric fluidized bed demonstration project. Quarterly technical progress report, October--December 1990

    SciTech Connect

    Not Available

    1991-01-31

    During the fourth quarter of 1990, steady-state performance testing at the Nucla Circulating Fluidized Bed (CFB) resumed under sponsorship of the US Department of Energy. Co-sponsorship of the Demonstration Test Program by the Electric Power Research Institute (EPRI) was completed on June 15, 1990. From October through December, 1990, Colorado-Ute Electric Association (CUEA) completed a total of 23 steady-state performance tests, 4 dynamic tests, and set operating records during November and December as the result of improved unit operating reliability. Highlight events and achievements during this period of operation are presented.

  16. MTG process in a fluidized bed with catalyst circulation: Operation and simulation of an experimental unit

    SciTech Connect

    Ortega, J.M.; Gayubo, A.G.; Aguayo, A.T.; Olazar, M.; Bilbao, J.

    1998-11-01

    The simulation of the MTG process has been studied in a fluidized bed with circulation of the catalyst (prepared based on a HZSM-5 zeolite). The simulation has been carried out by taking into account the activity distribution of the catalyst particles in the bed and by using experimentally determined kinetic models for the reaction at zero time on stream and for the catalyst deactivation. The results of the simulation have been proven in an experimental laboratory unit by operating in the range between 380 and 420 C, with different values of space time and of average residence time of the catalyst.

  17. Flow Regime Study in a High Density Circulating Fluidized Bed Riser with an Abrupt Exit

    SciTech Connect

    Mei, J.S.; Shadle, L.J.; Yue, P.C.; Monazam, E.R.

    2007-01-01

    Flow regime study was conducted in a 0.3 m diameter, 15.5 m height circulating fluidized bed (CFB) riser with an abrupt exit at the National Energy Technology Laboratory of the U.S. Department of Energy. Local particle velocities were measured at various radial positions and riser heights using an optical fiber probe. On-line measurement of solid circulating rate was continuously recorded by the Spiral. Glass beads of mean diameter 61 μm and particle density of 2,500 kg/m3 were used as bed material. The CFB riser was operated at various superficial gas velocities ranging from 3 to 7.6 m/s and solid mass flux from 20 to 550 kg/m2-s. At a constant riser gas velocity, transition from fast fluidization to dense suspension upflow (DSU) regime started at the bottom of the riser with increasing solid flux. Except at comparatively low riser gas velocity and solid flux, the apparent solid holdup at the top exit region was higher than the middle section of the riser. The solid fraction at this top region could be much higher than 7% under high riser gas velocity and solid mass flux. The local particle velocity showed downward flow near the wall at the top of the riser due to its abrupt exit. This abrupt geometry reflected the solids and, therefore, caused solid particles traveling downward along the wall. However, at location below, but near, the top of the riser the local particle velocities were observed flowing upward at the wall. Therefore, DSU was identified in the upper region of the riser with an abrupt exit while the fully developed region, lower in the riser, was still exhibiting core-annular flow structure. Our data were compared with the flow regime boundaries proposed by Kim et al. [1] for distinguishing the dilute pneumatic transport, fast fluidization, and DSU.

  18. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    SciTech Connect

    Wei-Ping Pan; Songgeng Li; John T. Riley

    2005-10-01

    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 July 1, 2005 through September 30, 2005. The following tasks have been completed. First, the construction of the Circulating Fluidized-Bed (CFB) Combustor Building was completed. The experimental facilities have been moved into the CFB Combustor Building. Second, the fabrication and manufacture of the CFBC Facility is in the final stage and is expected to be completed before November 30, 2005. Third, the drop tube reactor has been remodeled and installed to meet the specific requirements for the investigation of the effects of flue gas composition on mercury oxidation. This study will start in the next quarter. Fourth, the effect of sulfur dioxide on molecular chlorine via the Deacon reaction was investigated. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described in this report.

  19. Calculations of the time-averaged local heat transfer coefficients in circulating fluidized bed

    SciTech Connect

    Dai, T.H.; Qian, R.Z.; Ai, Y.F.

    1999-04-01

    The great potential to burn a wide variety of fuels and the reduced emission of pollutant gases mainly SO{sub x} and NO{sub x} have inspired the investigators to conduct research at a brisk pace all around the world on circulating fluidized bed (CFB) technology. An accurate understanding of heat transfer to bed walls is required for proper design of CFB boilers. To develop an optimum economic design of the boiler, it is also necessary to know how the heat transfer coefficient depends on different design and operating parameters. It is impossible to do the experiments under all operating conditions. Thus, the mathematical model prediction is a valuable method instead. Based on the cluster renewal theory of heat transfer in circulating fluidized beds, a mathematical model for predicting the time-averaged local bed-to-wall heat transfer coefficients is developed. The effects of the axial distribution of the bed density on the time-average local heat transfer coefficients are taken into account via dividing the bed into a series of sections along its height. The assumptions are made about the formation and falling process of clusters on the wall. The model predictions are in an acceptable agreement with the published data.

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

    DOEpatents

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

    2015-02-24

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

  1. Circulating fluidized bed tehnology in biomass combustion-performance, advances and experiences

    SciTech Connect

    Mutanen, K.I.

    1995-11-01

    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 US 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.

  2. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    SciTech Connect

    Wei-Ping Pan; Yan Cao; John Smith

    2007-03-31

    This report is to present the progress made on the project entitled ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period January 1, 2007 through March 31, 2007. The effort in this quarter has concentrated on installing the CFBC Facility and for conducting cold fluidization operations tests in the CFBC facility. The assembly of the ash recirculation pipe duct from the cyclones back to the bed area of the combustor, including the upper and lower loop seals was completed. The electric bed pre-heater was installed to heat the fluidizing air as it enters the wind box. The induced draft fan along with its machine base and power supply was received and installed. The flue gas duct from secondary cyclone outlet to induced draft fan inlet was received and installed, as well as the induced fan flue gas discharge duct. Pressure testing from the forced draft fan to the outlet of the induced fan was completed. In related research a pilot-scale halogen addition test was conducted in the empty slipstream reactor (without (Selective Catalytic Reduction) SCR catalyst loading) and the SCR slipstream reactor with two commercial SCR catalysts. The greatest benefits of conducting slipstream tests can be flexible control and isolation of specific factors. This facility is currently used in full-scale utility and will be combined into 0.6MW CFBC in the future. This work attempts to first investigate performance of the SCR catalyst in the flue gas atmosphere when burning Powder River Basin (PRB), including the impact of PRB coal flue gas composition on the reduction of nitrogen oxides (NOx) and the oxidation of elemental mercury (Hg(0)) under SCR conditions. Secondly, the impacts of hydrogen halogens (Hydrogen fluoride (HF), Hydrogen chloride (HCl), Hydrogen Bromide (HBr) and Hydrogen Iodine (HI)) on Hg(0) oxidation and their mechanisms can be explored.

  3. Simultaneous carbon and nitrogen removal in anoxic-aerobic circulating fluidized bed biological reactor (CFBBR).

    PubMed

    Cui, Y; Nakhla, G; Zhu, J; Patel, A

    2004-06-01

    Biological nutrient removal (BNR) in municipal wastewater treatment to remove carbonaceous substrates and nutrients, has recently become increasingly popular worldwide due to increasingly stringent regulations. Biological fluidized bed (BFB) technology, which could be potentially used for BNR, can provide some advantages such as high efficiency and a compact structure. This work shows the results of simultaneous elimination of organic carbon and nitrogen using a circulating fluidized bed biological reactor (CFBBR, which has been developed recently for chemical engineering processes. The CFBBR has two fluidized beds, running as anoxic and aerobic processes to accomplish simultaneous nitrification and denitrification, with continuous liquid recirculation through the anoxic bed and the aerobic bed. Soluble COD concentrations in the effluent ranging from 4 to 20 mg l(-1) were obtained at varying COD loading rates; ammonia nitrogen removal efficiencies averaged in excess of 99% at a minimum total hydraulic retention time (HRT) of 2.0 hours over a temperature range of 25 degrees C to 28 degrees C. Effluent nitrate nitrogen concentration of less than 5 mg l(-1) was achieved by increasing effluent recycle rate. No nitrite accumulation was observed either in the anoxic bed or in the aerobic bed. The system was able to treat grit chamber effluent wastewater at a HRT of 2.0 hours while achieving average effluent BOD, COD, NH3-N, TKN, nitrates, total phosphate, TSS and VSS concentrations of 10 mg l(-1), 18 mg l(-1), 1.3 mg l(-1), 1.5 mg l(-1), 7 mg l(-1), 2.0 mg l(-1), 10 mg l(-1) and 8 mg l(-1) respectively. The CFBBR appears to be not only an excellent alternative for conventional activated sludge type BNR technologies but also capable of processing much higher loadings that are suitable for industrial applications.

  4. Use potential of ash from circulating pressurized fluidized bed combustors using low-sulfur subbituminous coal

    SciTech Connect

    Bland, A.E.; Brown, T.H.; Georgiou, D.N.; Young, L.J.; Ashbaugh, M.B.; Wheeldon, J.

    1995-12-31

    The commercial introduction of pressurized fluidized bed combustion (PFBC) has spurred evaluation of ash management options for this technology. The unique operating characteristics of PFBC compared to atmospheric fluidized bed combustion (AFBC) units indicates that PFBC ash will exhibit unique chemical and physical characteristics, and hence, unique ash use opportunities. Western Research Institute (WRI) has initiated a study of the use properties of PFBC ashes involving both an assessment of the potential markets, as well as a technical feasibility study of specific use options. The market assessment is designed to address six applications including: (1) structural fill, (2) road base construction, (3) supplementary cementing materials in portland cement, (4) bricks and blocks, (5) synthetic aggregate, and (6) agricultural/soil amendment applications. Ashes from the Ahlstrom circulating PFBC pilot facility in Karhula, Finland, combusting western US low-sulfur subbituminous coal with limestone sorbent, were made available for the technical feasibility study. The technical feasibility study examined the use of PFBC ash in construction related applications, including its use as a supplemental cementing material in concrete, fills and embankments, soil stabilization, and synthetic aggregate production. In addition, testing was conducted to determine the technical feasibility of PFBC ash as a soil amendment for agriculture and reclamation applications.

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

    SciTech Connect

    Wei-Ping Pan, Kunlei Liu; John T. Riley

    2004-07-30

    This report presents the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the quarter April 1--June 30, 2004. The following tasks have been completed. First, the final specifications for the renovation of the new Combustion Laboratory and the construction of the CFB Combustor Building have been delivered to the architect, and invitations for construction bids for the two tasks have been released. Second, the component parts of the CFBC system have been designed after the design work for assembly parts of the CFBC system was completed. Third, the literature pertaining to Polychlorinated Dibenzo-p-Dioxins (PCDD) and Polychlorinated Dibenzofurans (PCDF) released during the incineration of solid waste, including municipal solid waste (MSW) and refuse-derived fuel (RDF) have been reviewed, and an experimental plan for fundamental research of MSW incineration on a simulated fluidized-bed combustion (FBC) facility has been prepared. Finally, the proposed work for the next quarter has been outlined in this report.

  6. Circulating fluidized bed hydrodynamics experiments for the multiphase fluid dynamics research consortium (MFDRC).

    SciTech Connect

    Oelfke, John Barry; Torczynski, John Robert; O'Hern, Timothy John; Tortora, Paul Richard; Bhusarapu, Satish; Trujillo, Steven Mathew

    2006-08-01

    An experimental program was conducted to study the multiphase gas-solid flow in a pilot-scale circulating fluidized bed (CFB). This report describes the CFB experimental facility assembled for this program, the diagnostics developed and/or applied to make measurements in the riser section of the CFB, and the data acquired for several different flow conditions. Primary data acquired included pressures around the flow loop and solids loadings at selected locations in the riser. Tomographic techniques using gamma radiation and electrical capacitance were used to determine radial profiles of solids volume fraction in the riser, and axial profiles of the integrated solids volume fraction were produced. Computer Aided Radioactive Particle Tracking was used to measure solids velocities, fluxes, and residence time distributions. In addition, a series of computational fluid dynamics simulations was performed using the commercial code Arenaflow{trademark}.

  7. Calculation and Analysis of Heat Transfer Coefficients in a Circulating Fluidized Bed Boiler Furnace

    NASA Astrophysics Data System (ADS)

    Wang, Zhiwei; Yang, Jianhua; Li, Qinghai

    A new way for the circulating fluidized bed (CFB) boiler research is proposed by the supervisory information system (SIS) in power plant level. The heat transfer coefficient in CFB boiler furnace is calculated and analyzed by the SIS calculation analysis in a commercial CFB boiler, the way how to calculate the heat transfer coefficient in SIS is introduced, and the heat transfer coefficient is accurately received by calculating a large amount of data from database. The relation about the heat transfer coefficient to unit load, bed temperature, bed velocity, and suspension density is analyzed; the linear relation could be accepted for the commercial CFB design. A new calculating and simple way for the heat transfer coefficient of CFB boiler is proposed for CFB boiler design. Using this research result, the reheat spray water flux larger than the design value in lots of commercial CFB boilers is analyzed; the main reason is the designed heat transfer coefficient smaller than the actual value.

  8. Latest Evolution of Oxy-Fuel Combustion Technology in Circulating Fluidized Bed

    NASA Astrophysics Data System (ADS)

    Zhao, C. S.; Duan, L. B.; Chen, X. P.; Liang, C.

    O2/CO2 combustion technology is considered as one of the most promising method to mitigate the greenhouse effect, and the O2/CO2 CFB combustion technology which combines O2/CO2 combustion technology with circulating fluidized bed (CFB) combustion technology will extend both their advantages. The latest research findings on O2/CO2 CFB combustion technology are reviewed, the combustion and pollutant emission characteristics are expatiated, its effects on the boiler design are analyzed, the techno-economic assessment are reported and the key issues are indicated in the paper. O2/CO2 CFB combustion technology has no insolvable bottleneck in its development and due to its economic superiority; it is one of the most important clean coal technologies.

  9. The Hopkins repowering project a utility scale circulating fluidized bed boiler

    SciTech Connect

    Brinkworth, G.S. ); Hobday, J.M. ); Mazur, K.S. ); Goldich, S.J. ); Sturdevant, B.L. and Associates, Denver, CO )

    1991-01-01

    The existing boiler at the City of Tallahassee's 250 MW Hopkins Station Unit 2 fires natural gas and No. 6 fuel oil. In November 1990, the City and the U.S. Department of Energy (DOE) signed an agreement to repower the existing Unit 2 with a single circulating fluidized bed (CFB) boiler, as part of DOE's Clean Coal Technology Program. The CFB boiler, which will be fired with Eastern Bituminous coal, will be approximately twice the capacity of currently operating CFB boilers. This paper outlines objectives of the project and its participants. It will highlight significant technological and environmental issues and addresses the following subjects. Historical perspective of the project; The project organization; Project scope, schedule and cost; and Permitting and environmental issues.

  10. Colorado-Ute Nucla Station circulating-fluidized-bed (CFB) demonstration

    SciTech Connect

    Not Available

    1991-10-01

    The Electric Power Research Institute (EPRI) has completed a demonstration project at Nucla Station, owned and operated by Colorado-Ute Electric Association. This station was recently retrofitted with a circulating fluidized bed (CFB) boiler and its capacity was raised from 36 to 110 MWe. The new boiler supplies all the steam needed to operate the retrofitted station. At the time of its commissioning in 1987, the boiler was the largest of its kind in the world and represented the first full-scale utility CFB installation. The EPRI demonstration project is documented in two reports. The first of these, titled Test Program Preparation,'' covers the preparatory work leading up to actual testing. The second, titled Test Program Results,'' is contained in this volume and includes a description of the test work and its results as well as the conclusions with respect to the merits of CFB boilers in utility service. 124 figs., 28 tabs.

  11. The simulation of influence of different coals on the circulating fluidized bed Boiler's combustion performance

    NASA Astrophysics Data System (ADS)

    Yong, Yumei; Lu, Qinggang

    2003-05-01

    The combustion performance of the boiler largely depends on the coal type. Lots of experimental research shows that different fuels have different combustion characteristics. It is obvious that fuel will change the whole operating performance of Circulating Fluidized Bed Combustion (CFBC). We know even in a pilot-scale running boiler, the measurement of some parameters is difficult and costly. Therefore, we developed the way of simulation to evaluate the combustion performance of Chinese coals in CFB. The simulation results show that, different coals will result in different coal particle diameter and comminution depending on their mineral component and the change will affect the distribution of ash in CFBC system. In a word, the computational results are in accordance with experimental results qualitatively but there are some differences quantitatively.

  12. Design and Operation of Large Size Circulating Fluidized Bed Boiler Fired Slurry and Gangue

    NASA Astrophysics Data System (ADS)

    Man, Zhang; Rushan, Bie; Fengjun, Wang

    The way which burns slurry and gangue to generate electricity and provide heat has been always desired. If mixture of slurry and gangue are burnt by conventional combustion technology, it is difficult to be satisfied., but for circulating fluidized bed(CFB) boiler, it is flexible for fuels and it is easy to desulfurize and DeNox in the furnace of the boiler. There are lots of advantages to burning the mixture of slurry and gangue in CFB boiler. This technology has been researched and practiced for many years, it is mature now and has been used widely, by now, 50MW, 135MW and 300MW CFB boiler which burn the mixture of slurry and gangue have already been operated in China. In the paper, slurry characteristic and conveying is described, the design and operation of boilers mentioned above will be also introduced in detail.

  13. Research on carbon content in fly ash from circulating fluidized bed boilers

    SciTech Connect

    Xianbin Xiao; Hairui Yang; Hai Zhang; Junfu Lu; Guangxi Yue

    2005-08-01

    The carbon content in the fly ash from most Chinese circulating fluidized bed (CFB) boilers is much higher than expected, which directly influences the combustion efficiency. In the present paper, carbon burnout was investigated in both field tests and laboratory experiments. The effect of coal property, operation condition, gas-solid mixing, char deactivation, residence time, and cyclone performance are analyzed seriatim based on a large amount of experimental results. A coal index is proposed to describe the coal rank, having a strong effect on the char burnout. Bad gas-solid mixing in the furnace is another important reason of the higher carbon content in the fly ash. Some chars in the fly ash are deactivated during combustion of large coal particles and have very low carbon reactivity. Several suggestions are made about design, operation, and modification to reduce the carbon content in the fly ash. 14 refs., 14 figs., 1 tab.

  14. Characteristics modeling for supercritical circulating fluidized bed boiler working in oxy-combustion technology

    NASA Astrophysics Data System (ADS)

    Balicki, Adrian; Bartela, Łukasz

    2014-06-01

    Among the technologies which allow to reduce greenhouse gas emission, mainly carbon dioxide, special attention deserves the idea of `zeroemission' technology based on boilers working in oxy-combustion technology. In the paper the results of analyses of the influence of changing two quantities, namely oxygen share in oxidant produced in the air separation unit, and oxygen share in oxidant supplied to the furnace chamber on the selected characteristics of a steam boiler including the degree of exhaust gas recirculation, boiler efficiency and adiabatic flame temperature, was examined. Due to the possibility of the integration of boiler model with carbon dioxide capture, separation and storage installation, the subject of the analysis was also to determine composition of the flue gas at the outlet of a moisture condensation installation. Required calculations were made using a model of a supercritical circulating fluidized bed boiler working in oxy-combustion technology, which was built in a commercial software and in-house codes.

  15. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    SciTech Connect

    Wei-Ping Pan; Zhongxian Cheng; Yan Cao; John Smith

    2006-09-30

    This report is to present the progress made on the project entitled ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period July 1, 2006 through September 30, 2006. The following activities have been completed: the steel floor grating around the riser in all levels and the three-phase power supply for CFBC System was installed. Erection of downcomers, loop seals, ash bunker, thermal expansion joints, fuel and bed material bunkers with load cells, rotary air-lock valves and fuel flow monitors is underway. Pilot-scale slipstream tests conducted with bromine compound addition were performed for two typical types of coal. The purposes of the tests were to study the effect of bromine addition on mercury oxidization. From the test results, it was observed that there was a strong oxidization effect for Powder River Basin (PRB) coal. The proposed work for next quarter and project schedule are also described.

  16. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    SciTech Connect

    Wei-Ping Pan; Songgeng Li

    2006-01-01

    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, 2005 through December 31, 2005. Work was performed on the following activities. First, the fabrication and manufacture of the CFBC Facility is nearly completed. The erection of the CFBC facility is expected to start in the second week of February, 2006. Second, effect of flue gas components on mercury oxidation was investigated in a drop tube reactor. As a first step, experiment for mercury oxidation by chlorine was investigated. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described in this report.

  17. Occurrence of polycyclic aromatic hydrocarbons in dust emitted from circulating fluidized bed boilers.

    PubMed

    Kozielska, B; Konieczyńiski, J

    2008-11-01

    Occurrence of polycyclic aromatic hydrocarbons (PAHs) in granulometric fractions of dust emitted from a hard coal fired circulating fluidized bed (CFB) boiler was investigated. The dust was sampled with the use of a Mark III impactor. In each fraction of dust, by using gas chromatography (GC), 16 selected PAHs and total PAHs were determined and the toxic equivalent B(a)P (TE B(a)P) was computed. The results, recalculated for the standard granulometric fractions, are presented as concentrations and content of the determined PAHs in dust. Distributions of PAHs and their profiles in the granulometric dust fractions were studied also. The PAHs in dust emitted from the CFB boiler were compared with those emitted from mechanical grate boilers; a distinctly lower content of PAHs was found in dust emitted from the former.

  18. Fabrication and properties of foam geopolymer using circulating fluidized bed combustion fly ash

    NASA Astrophysics Data System (ADS)

    Liu, Ze; Shao, Ning-ning; Wang, Dong-min; Qin, Jun-feng; Huang, Tian-yong; Song, Wei; Lin, Mu-xi; Yuan, Jin-sha; Wang, Zhen

    2014-01-01

    In recent years, circulating fluidized bed combustion fly ash (CFA) is used as a raw material for geopolymer synthesis. Hydrogen peroxide was employed as a foaming agent to prepare CFA-based foam geopolymer. The particle distribution, mineral composition, and chemical composition of CFA were examined firstly. Geopolymerization products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF). The CFA-based foam geopolymer was successfully fabricated with different contents of hydrogen peroxide and exhibited uncompleted alkali reaction and reasonable strength with relative low atomic ratios of Si/Al and Si/Na. Type-C CFA in this research could be recycled as an alternative source material for geopolymer production.

  19. Modified graphical autocatalytic set model of combustion process in circulating fluidized bed boiler

    NASA Astrophysics Data System (ADS)

    Yusof, Nurul Syazwani; Bakar, Sumarni Abu; Ismail, Razidah

    2014-07-01

    Circulating Fluidized Bed Boiler (CFB) is a device for generating steam by burning fossil fuels in a furnace operating under a special hydrodynamic condition. Autocatalytic Set has provided a graphical model of chemical reactions that occurred during combustion process in CFB. Eight important chemical substances known as species were represented as nodes and catalytic relationships between nodes are represented by the edges in the graph. In this paper, the model is extended and modified by considering other relevant chemical reactions that also exist during the process. Catalytic relationship among the species in the model is discussed. The result reveals that the modified model is able to gives more explanation of the relationship among the species during the process at initial time t.

  20. Carbon monoxide formation and emissions during waste incineration in a grate-circulating fluidized bed incinerator.

    PubMed

    Yanguo Zhang; Qinghai Li; Aihong Meng; Changhe Chen

    2011-03-01

    This paper presents an experimental study of carbon monoxide (CO) formation and emissions in both grate drying bed incinerators and circulating fluidized bed (CFB) incinerators to simulate the two key parts of a combined grate and circulating fluidized bed (grate-CFB) incinerator in order to investigate pollutant emission control in municipal solid waste (MSW) combustion that occurs in a grate-CFB incinerator utilizing a patented technology. Polyvinyl chloride, polystyrene, kitchen waste, paper, textile, etc. were chosen to simulate the MSW. The effects of temperature, air staging, and moisture on the CO formation and emissions were analysed for both the grate drying bed combustion and the CFB combustion. In the grate drying bed, the low temperatures increased the carbon to CO conversion rate which also increased slightly with the moisture content. Industrial field tests in a commercial grate-CFB incinerator showed that the CO concentration at the grate drying bed exit was very high and decreased along furnace height. The carbon to CO conversion rates were 0-20% for the grate drying bed which exceeded the range of 0.8-16% measured in a grate drying bed exit of the commercial grate-CFB incinerator tests. In the commercial grate-CFB incinerator tests, at excess air ratios ranging from 1.5-2.0 or more, the CO emissions decreased to a low and stable level, whose corresponding carbon to CO conversion rates were far lower than 0-10%. The low CO emission is one of the factors enabling the polychlorinated dibenzodioxin/polychlorinated dibenzofuran emissions to satisfy the Chinese national regulations.

  1. Combustion characteristics of spent catalyst and paper sludge in an internally circulating fluidized-bed combustor.

    PubMed

    Roh, Seon Ah; Jung, Dae Sung; Kim, Sang Done; Guy, Christophe

    2005-09-01

    Combustion of spent vacuum residue hydrodesulfurization catalyst and incineration of paper sludge were carried out in thermo-gravimetric analyzer and an internally circulating fluidized-bed (ICFB) reactor. From the thermo-gravimetric analyzer-differential thermo-gravimetric curves, the pre-exponential factors and activation energies are determined at the divided temperature regions, and the thermo-gravimetric analysis patterns can be predicted by the kinetic equations. The effects of bed temperature, gas velocity in the draft tube and annulus, solid circulation rate, and waste feed rate on combustion efficiency of the wastes have been determined in an ICFB from the experiments and the model studies. The ICFB combustor exhibits uniform temperature distribution along the bed height with high combustion efficiency (>90%). The combustion efficiency increases with increasing reaction temperature, gas velocity in the annulus region, and solid circulation rate and decreases with increasing waste feed rate and gas velocity in the draft tube. The simulated data from the kinetic equation and the hydrodynamic models predict the experimental data reasonably well.

  2. 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.

  3. Solids circulation around a jet in a fluidized bed gasifier. Final technical report, September 1, 1978-September 30, 1980

    SciTech Connect

    Gidaspow, D.; Ettehadieh, B.; Lin, C.; Goyal, A.; Lyczkowski, R.W.

    1980-01-01

    The object of this investigation was to develop an experimentally verified hydrodynamic model to predict solids circulation around a jet in a fluidized bed gasifier. Hydrodynamic models of fluidization use the principles of conservation of mass, momentum and energy. To account for unequal velocities of solid and fluid phases, separate phase momentum balances are developed. Other fluid bed models used in the scale-up of gasifiers do not employ the principles of conservation of momentum. Therefore, these models cannot predict fluid and particle motion. In such models solids mixing is described by means of empirical transfer coefficients. A two dimensional unsteady state computer code was developed to give gas and solid velocities, void fractions and pressure in a fluid bed with a jet. The growth, propagation and collapse of bubbles was calculated. Time-averaged void fractions were calculated that showed an agreement with void fractions measured with a gamma ray densitometer. Calculated gas and solid velocities in the jet appeared to be reasonable. Pressure and void oscillations also appear to be reasonable. A simple analytical formula for the rate of solids circulation was developed from the equations of change. It agrees with Westinghouse fluidization data in a bed with a draft tube. One dimensional hydrodynamic models were applied to modeling of entrained-flow coal gasification reactors and compared with data. Further development of the hydrodynamic models should make the scale-up and simulation of fluidized bed reactors a reality.

  4. 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.

  5. Low temperature SO{sub 2} removal with solid sorbents in a circulating fluidized bed absorber. Final report

    SciTech Connect

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

    1994-10-10

    A novel flue gas desulfurization technology has been developed at the University of Cincinnati incorporating a circulating fluidized bed absorber (CFBA) reactor with dry sorbent. The main features of CFBA are high sorbent/gas mixing ratios, excellent heat and mass transfer characteristics, and the ability to recycle partially utilized sorbent. Subsequently, higher SO{sub 2} removal efficiencies with higher overall sorbent utilization can be realized compared with other dry sorbent injection scrubber systems.

  6. The compact circulating fluidized bed boiler with a finned tube impact separator and a uniflow square cyclone

    SciTech Connect

    Li Xiaodong; Chi Yong; Yan Jianhua; Jiang Xuguang; Yang Jialin; Huang Guoquan; Ni Mingjiang; Cen Kefa

    1999-07-01

    Institute for Thermal Power Engineering, Zhejiang University has introduced a circulating fluidized bed boiler with two stage compact separation. A finned tube impact separator is located at the outlet of the furnace and a uniflow square cyclone is adopted behind the superheater. The flow characteristics of the finned tube separator are measured using a three dimensional particles dynamics analyzer. The measurements show that the reflux flow existing near the front of a finned tube has a very important effect on particle separation. The shape of a uniflow square cyclone is different with a conventional uniflow cyclone and can be laid conveniently in the flue duct of the boiler. A lot of experimental studies have been done focusing on the above separators' performances. The experimental results show that separation efficiency of the uniflow square cyclone can be up to 99% for particles with mean size 0.167 mm and its pressure drop is lower than 1,000 Pa. To change the shape of the cyclone's exhaust pipe is very effective. Based on the results, the optimization design of the separators is reported. The finned tube impact separator has been successfully applied in several circulating fluidized bed boilers. Institute for Thermal Power Engineering, Zhejiang University has designed a compact circulating fluidized bed boiler with the finned tube impact separator and a uniflow square cyclone, and the boilers capacity is 65 t/h (12 MWe).

  7. Combustion of municipal solid wastes with oil shale in a circulating fluidized bed. Final report

    SciTech Connect

    1996-06-30

    The problem addressed by our invention is that of municipal solid waste utilization. The dimensions of the problem can be visualized by the common comparison that the average individual in America creates in five years time an amount of solid waste equivalent in weight to the Statue of Liberty. The combustible portion of the more than 11 billion tons of solid waste (including municipal solid waste) produced in the United States each year, if converted into useful energy, could provide 32 quads per year of badly needed domestic energy, or more than one-third of our annual energy consumption. Conversion efficiency and many other factors make such a production level unrealistic, but it is clear that we are dealing with a very significant potential resource. This report describes research pertaining to the co-combustion of oil shale with solid municipal wastes in a circulating fluidized bed. The oil shale adds significant fuel content and also constituents that can possible produce a useful cementitious ash.

  8. Circulating fluidized-bed boilers: Enhancing reagent utilization while maintaining proper SO{sub 2} removal

    SciTech Connect

    Dubose, R.E.; Ray, D.M.; Wofford, J.; Buecker, B.

    1997-12-31

    Unit performance, and related operation and maintenance costs, for circulating fluidized bed (CFB) combustors are very dependent on the sorbent selected for SO{sub 2} removal. Limestone is the typical reagent of choice, but variations in quality can have a dramatic impact on the reaction efficiency. This paper discusses the results of full-scale tests and subsequent use of a high-quality sorbent in the two CFBs serving the University of North Carolina at Chapel Hill. The tests were necessary because of the desire to optimize performance based on the economics of limestone utilization and ash disposal. It was considered, also, that the reagent in use prior to the tests was not very reactive and caused ash handling problems. Project organizers used the full-scale tests to examine the effects of sorbent quality and grind size on the efficiency of the process. The tests indicated that reagent consumption would be reduced by 50% or more with the new sorbent. Plant personnel verified this conclusion when they began feeding the new reagent on a permanent basis. Reagent usage and ash production significantly decreased and have remained low in the three years since the change was made. The results outlined in this paper clearly indicate the large impact that reagent quality has on CFB operation. For present and prospective CFB managers, these results can justify the search for, and use of, limestone sorbents that might otherwise be considered too expensive or too distant from the plant. 39 figs.

  9. 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.

  10. Cyclone performance; The key to feed utilization in circulating fluidized bed boilers

    SciTech Connect

    Tsao, T.R.; Herb, B.E.; Lewnard, J.J.; Wang, S.I. )

    1992-01-01

    High utilization of coal and limestone feedstock in circulating fluidized bed (CFB) combustors is critical to minimize operating costs and solid waste generation. Pilot-scale test results typically indicate 50% calcium utilization (Ca/S = 1:1) and greater than 99% carbon burnout. Recent performance data taken for Stockton CFB indicates that a large fraction of the unburned carbon and unreacted limestone escapes the boiler with the fly ash particles smaller than 100 {mu}m in size. This observation was explained by the short residence times of fine particles in the CFB boiler. An analysis of the CFB system suggests that this problem is caused by the inability of the cyclone to capture smaller particles and return them to the boiler to be more completely utilized. This paper reports that a sensitivity study revealed that feedstock utilization is sensitive to cyclone grade efficiency for small particle sizes. in addition, the results show how bed particle size, fly-bottom ash split, solids recirculation rate, and heat transfer in CFB's are affected by cyclone performance.

  11. 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.

  12. Combustion of various types of residues in a circulating fluidized bed combustor

    SciTech Connect

    Gulyurtlu, I.; Frade, E.; Lopes, H.; Figueiredo, F.; Cabrita, I.

    1997-12-31

    Combustion studies of different wastes alone or mixed were undertaken in an atmospheric circulating fluidized bed. The combustor was operated over a temperature range of 700 to 1,000 C. The residues studied included biomass, tyres, and oil sludges. The main parameters that were investigated are (1) where and how to feed residues, (2) the ratios of amounts of residues when they are burned mixed, (3) air staging, and (4) excess air levels along the riser. The main conclusions are: (1) a large variation in the combustion efficiency was observed depending on the fuel, its particle size and where the fuel was fed in the combustor, (2) in the case of the use of mixture of wastes the utilization of biomass residues as the base fuel increased their combustion efficiency and resulted in very stable combustion conditions, (3) temperature appeared to be still very influential in reducing the levels of unburned carbon and hydrocarbons released from residues, and (4) the air staging in the freeboard improved combustion efficiency by enhancing the combustion of volatiles released from residues in the riser and produced lower emissions of both NO{sub x}. Particles collected in the cyclone and those removed from the bed were also analyzed to determine the levels of heavy metals. When oil sludge was added, high amounts of very fine particles of heavy metals were observed in the combustion gases.

  13. 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.

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

    SciTech Connect

    Xiaolin Wei; Yang Wang; Dianfu Liu; Hongzhi Sheng; Wendong Tian; Yunhan Xiao

    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 of 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.

  15. Heavy metal behavior during circulating fluidized bed combustion of willow (Salix)

    SciTech Connect

    Lind, T.; Kauppinen, E.I.; Nilsson, K.; Sfiris, G.; Maenhaut, W.; Huggins, F.E.

    1999-07-01

    The behavior of the heavy metals Cd, Pb, Cu and Zn was studied experimentally at a 35 MW circulating fluidized bed boiler. The fuel was a Swedish willow (Salix) and quartz sand was used as an additional bed material. Almost no Cd was retained in the bottom ash, whereas Zn was clearly enriched in the bottom ash. 15--27% of Pb was in the gas phase downstream of the cyclone at T = 810 C, but less than 3% of Cd, Cu, or Zn. In the convective pass the gas phase Pb reacted with the coarse fly ash particles. Consequently, all the heavy metals were found entirely in the coarse fly ash particles downstream of the convective pass at T = 150 C. The heavy metals were not enriched in the fine fly ash particles. The coarse fly ash particles were large agglomerates consisting of up to thousands of submicron primary particles. These agglomerates were very effective in capturing volatile heavy metals into the coarse fly ash fraction hindering their condensation and subsequent enrichment in the fine particles.

  16. Experimental Study of Nitrogen Oxide Emissions in a Circulating Fluidized Bed

    NASA Astrophysics Data System (ADS)

    Liu, R. W.; Zhou, Q. L.; Hui, S. E.; Xu, T. M.

    The experimental study was carried out on the emission characteristics of nitrogen oxide in a 0.3MW circulating fluidized bed as well as analysis of the formation and destruction mechanism of nitrogen oxide. Several variables associated with the combustion system were investigated in the experiment, which include bed temperature, excess air, primary-to-secondary air ratio, and coal species. It is found that the NO x emissions decrease along the height of the furnace, while the N2O emissions increase continuously. More NO x emissions and less N2O emissions are generated as the bed temperature increases. It is also illustrated that an increase of air stoichiometry leads to a significant NO x increase and an obvious N2O increase. And air staging is proved to be an effective way to control the nitrogen oxide emissions in the fluid bed. Besides, it is also shown in the experiment that the concentration of NO x and N2O is higher during the combustion of anthracite than that during the combustion of bituminous.

  17. Modeling of hydrodynamics of large scale atmospheric circulating fluidized bed coal combustors

    SciTech Connect

    Leretaille, P.Y.; Werther, J.; Briand, P.; Montat, D.

    1999-07-01

    A model for evaluation of the hydrodynamics of gas-solid flow in the riser of a circulating fluidized bed coal boiler is proposed. The 3D fields of the gas and solid velocities and of the solid concentration in the riser are estimated from measured data of the vertical pressure profile. The model includes semi-empirical laws developed on the basis of a set of experimental data on six industrial boilers ranging from 12 MWth to 700 MWth. Its relevance for laboratory scale risers was not tested. The estimation of flow of solids near the walls was fulfilled with a special care due to the influence of this flow on heat transfer. For the validation of the model, measurements of solid concentration with guarded capacitance probes were performed in the 250 MWe Stein Industrie-Lurgi type CFB boiler in Gardanne, France. Finally, an attempt to predict the vertical pressure profile on the riser, starting from the operating conditions (and based on an empirical evaluation of the variation of the downward flow of solid from local conditions) is presented and compared to experimental data.

  18. Simultaneous carbon, nitrogen and phosphorous removal from municipal wastewater in a circulating fluidized bed bioreactor.

    PubMed

    Patel, Ajay; Zhu, Jesse; Nakhla, George

    2006-11-01

    In this study, the performance of the circulating fluidized bed bioreactor (CFBB) with anoxic and aerobic beds and employing lava rock as a carrier media for the simultaneous removal of carbon, nitrogen and phosphorus from municipal wastewater at an empty bed contact time (EBCT) of 0.82 h was discussed. The CFBB was operated without and with bioparticles' recirculation between the anoxic and aerobic bed for 260 and 110 d respectively. Without particles' recirculation, the CFBB was able to achieve carbon (C), total nitrogen (N) and phosphorous (P) removal efficiencies of 94%, 80% and 65% respectively, whereas with bioparticles' recirculation, 91%, 78% and 85% removals of C, N and P were achieved. The CFBB was operated at long sludge retention time (SRT) of 45-50 d, and achieved a sludge yield of 0.12-0.135 g VSS g COD(-1). A dynamic stress study of the CFBB was carried out at varying feed flow rates and influent ammonia concentrations to determine response to shock loadings. The CFBB responded favourably in terms of TSS and COD removal to quadrupling of the feed flow rate. However, nitrification was more sensitive to hydraulic shock loadings than to doubling of influent nitrogen loading.

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

    PubMed

    Xu, Hui; Li, Qin; Shen, Lifeng; Zhang, Mengqun; Zhai, Jianping

    2010-01-01

    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 solution 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.

  20. Synthesis of thermostable geopolymer from circulating fluidized bed combustion (CFBC) bottom ashes.

    PubMed

    Xu, Hui; Li, Qin; Shen, Lifeng; Wang, Wei; Zhai, Jianping

    2010-03-15

    Circulating fluidized bed combustion (CFBC) bottom ashes (CBAs) are a class of calcined aluminosilicate wastes with a unique thermal history. While landfill disposal of hazardous element-containing CBAs poses serious challenge, these wastes have long been neglected as source materials for geopolymer production. In this paper, geopolymerization of ground CBAs was investigated. Reactivity of the CBAs was analyzed by respective dissolution of the ashes in 2, 5, and 10N NaOH and KOH solutions. Geopolymer pastes were prepared by activating the CBAs by a series of alkalis hydroxides and/or sodium silicate solutions. Samples were cured at 40 degrees C for 168 h, giving a highest compressive strength of 52.9 MPa. Of the optimal specimen, characterization was conducted by TG-DTA, SEM, XRD, as well as FTIR analyses, and thermal stability was determined in terms of compressive strength evolution via exposure to 800 or 1050 degrees C followed by three cooling regimes, i.e. cooling in air, cooling in the furnace, and immerging in water. The results show that CBAs could serve as favorable source materials for thermostable geopolymers, which hold a promise to replace ordinary Portland cement (OPC) and organic polymers in a variety of applications, especially where fire hazards are of great concern.

  1. Feasibility of manufacturing geopolymer bricks using circulating fluidized bed combustion bottom ash.

    PubMed

    Chen, Chen; Li, Qin; Shen, Lifeng; Zhai, Jianping

    2012-06-01

    This paper presents a study on geopolymer bricks manufactured using bottom ash from circulating fluidized bed combustion (CFBC). The alkali activators used for synthesis were sodium silicate, sodium hydroxide, and potassium hydroxide and lithium hydroxide solutions. The study included the impact of alkali activator on compressive strength. The reaction products were analysed by XRD, FT-IR and SEM/EDS. The compressive strength of bricks was dependent on the modulus of the sodium silicate activator and the type and concentration of alkali activator. The highest compressive strength could be gained when the modulus was 1.5, and the value could reach 16.1 MPa (7 d after manufacture) and 21.9 MPa (28 d after manufacture). Under pure alkaline systems, the compressive strength was in the order of 10 M KOH > 10 M NaOH > 5 M LiOH > 5 M KOH > 5 M NaOH. Quartz was the only crystalline phase in the original bottom ash, and no new crystalline phase was found after the reaction. The main product of reaction was amorphous alkali aluminosilicate gel and a small amount of crystalline phase was also found by SEM.

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

    SciTech Connect

    Xu Hui; Li Qin; Shen Lifeng; Zhang Mengqun; Zhai Jianping

    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 solution 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.

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

    SciTech Connect

    Wei-Ping Pan; Kunlei Liu; John T. Riley

    2004-04-01

    The purpose of this report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the quarter January--March 2004. The following tasks have been completed. First, plans for the renovation of space for a new Combustion Laboratory for the CFBC Facility have progressed smoothly. Second, the design calculations, including the mass balances, energy balances, heat transfer, and strength calculations have been completed. Third, considerable modifications have been made on the draft design of the CFBC Facility based on discussions conducted during the project kick-off meeting held on January 13, 2004 at the National Energy Technology Laboratory (NETL). Comments received from various experts were also used to improve the design. Finally, the drawings of all assembly parts have been completed in order to develop specifications for the fabrication of individual parts. At the same time, the proposed work for the next quarter has been outlined in this report.

  4. Effect of flue gas recirculation on heat transfer in a supercritical circulating fluidized bed combustor

    NASA Astrophysics Data System (ADS)

    Błaszczuk, Artur

    2015-09-01

    This paper focuses on assessment of the effect of flue gas recirculation (FGR) on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB) combustor. The performance test in supercritical CFB combustor with capacity 966 MWth was performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater) and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.

  5. Design considerations and operating experience in firing refuse derived fuel in a circulating fluidized bed combustor

    SciTech Connect

    Piekos, S.J.; Matuny, M.

    1997-12-31

    The worldwide demand for cleaner, more efficient methods to dispose of municipal solid waste has stimulated interest in processing solid waste to produce refuse derived fuel (RDF) for use in circulating fluidized bed (CFB) boilers. The combination of waste processing and materials recovery systems and CFB boiler technology provides the greatest recovery of useful resources from trash and uses the cleanest combustion technology available today to generate power. Foster Wheeler Power Systems along with Foster Wheeler Energy Corporation and several other Foster Wheeler sister companies designed, built, and now operates a 1600 tons per day (TPD) (1450 metric tons) municipal waste-to-energy project located in Robbins, Illinois, a suburb of Chicago. This project incorporates waste processing systems to recover recyclable materials and produce RDF. It is the first project in the United States to use CFB boiler technology to combust RDF. This paper will provide an overview of the Robbins, Illinois waste-to-energy project and will examine the technical and environmental reasons for selecting RDF waste processing and CFB combustion technology. Additionally, this paper will present experience with handling and combusting RDF and review the special design features incorporated into the CFB boiler and waste processing system that make it work.

  6. The prediction of variability occurring in fluidized bed coating equipment. I. The measurement of particle circulation rates in a bottom-spray fluidized bed coater.

    PubMed

    Cheng, X X; Turton, R

    2000-01-01

    The purpose of this work was to investigate the effect that changes in design and process variables had on the movement of particles around a fluidized bed coating apparatus. To measure the mean and variance of the particle cycle time distribution (CTD), the number of passages taken by a magnetic tracer particle through the spray zone was measured by a detector coil wound around the partition. The reproducibility of the measurement technique was tested by taking repeated measurements of the tracer particle movement, using similar bed operating conditions, and the method was found to give reproducible results. A series of experiments was carried out by varying operating conditions such as the partition gap, fluidizing air rate, and partition diameter and length, and measuring the change in the rate at which the tracer particle circulated in the coating device. The results of the experiments showed that, over the range of parameters tested in this work, the partition gap had the strongest influence on the rate of particle circulation. Moreover, for the 6-in.-diameter Wurster process used in the current work, the mean circulation time for the 1.1-mm-diameter Nu-Pareil particles was found to vary over the range of 2.2-10.4 sec. In addition, the mean and standard deviation of the CTD could be linearly correlated over a wide range of operating conditions, with a correlation coefficient of 0.80. Finally, an estimate of the variability in mass coating uniformity was made based on the results from the cycle time distributions. It was concluded that the effect of variability in the CTD could account for only a small fraction of the variability in the observed mass coating distribution.

  7. GREENHOUSE GAS EMISSIONS CONTROL BY OXYGEN FIRING IN CIRCULATING FLUIDIZED BED BOILERS

    SciTech Connect

    Nsakala ya Nsakala; Gregory N. Liljedahl

    2003-05-15

    Given that fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic CO{sub 2} emissions. In this study, ALSTOM Power Inc. (ALSTOM) has investigated several coal fired power plant configurations designed to capture CO{sub 2} from effluent gas streams for use or sequestration. Burning fossil fuels in mixtures of oxygen and recirculated flue gas (made principally of CO{sub 2}) essentially eliminates the presence of atmospheric nitrogen in the flue gas. The resulting flue gas is comprised primarily of CO{sub 2}. Oxygen firing in utility scale Pulverized Coal (PC) fired boilers has been shown to be a more economical method for CO{sub 2} capture than amine scrubbing (Bozzuto, et al., 2001). Additionally, oxygen firing in Circulating Fluid Bed Boilers (CFB's) can be more economical than in PC or Stoker firing, because recirculated gas flow can be reduced significantly. Oxygen-fired PC and Stoker units require large quantities of recirculated flue gas to maintain acceptable furnace temperatures. Oxygen-fired CFB units, on the other hand, can accomplish this by additional cooling of recirculated solids. The reduced recirculated gas flow with CFB units results in significant Boiler Island cost savings. Additionally, ALSTOM has identified several advanced/novel plant configurations, which improve the efficiency and cost of the CO{sub 2} product cleanup and compression process. These advanced/novel concepts require long development efforts. An economic analysis indicates that the proposed oxygen-firing technology in circulating fluidized boilers could be developed and deployed economically in the near future in enhanced oil recovery (EOR) applications or enhanced gas recovery (EGR), such as coal bed methane recovery. ALSTOM received a Cooperative Agreement from the US Department

  8. In Developping a Bench-Scale Circulating Fluidized Bed Combustor to Burn High Ash Brazilian Coal-Dolomites Mixtures

    NASA Astrophysics Data System (ADS)

    Ramírez Behainne, Jhon Jairo; Hory, Rogério Ishikawa; Goldstein, Leonardo; Bernárdez Pécora, Araí Augusta

    This work considers some of the questions in burning high ash Brazilian coal-dolomite mixtures in a bench-scale circulating fluidized bed combustor (CFBC). Experimental tests were performed with the CE4500 coal from Santa Catarina State, in southern Brazil, with a Sauter mean diameter d p =43 μm. The coal particles were mixed with dolomite particles of d p = 111 μm and this fuel mixture was fed into the circulating fluidized reactor, previously loaded with quartz sand particles of d p =353 μm. This inert material was previously heated by the combustion of liquefied petroleum gas up to the ignition temperature of the fuel mixture. The CFBC unit has a 100mm internal diameter riser, 4.0m high, as well as a 62.8mm internal diameter downcomer. The loop has a cyclone, a sampling valve to collect particles and a 62.8mm internal diameter L-valve to recirculate the particles in the loop. A screw feeder with a rotation control system was used to feed the fuel mixture to the reactor. The operational conditions were monitored by pressure taps and thermocouples installed along the loop. A data acquisition system showed the main operational conditions to control. Experimental tests performed put in evidence the problems found during bed operation, with special attention to the solids feed device, to the L-valve operation, to particle size, solids inventory, fluidized gas velocity, fuel mixture and recirculated solids feeding positions.

  9. Design and construction of a circulating fluidized bed combustion facility for use in studying the thermal remediation of wastes

    NASA Astrophysics Data System (ADS)

    Rink, Karl K.; Kozinski, Janusz A.; Lighty, JoAnn S.; Lu, Quing

    1994-08-01

    Fluidized bed combustion systems have been widely applied in the combustion of solid fossil fuels, particularly by the power generation industry. Recently, attention has shifted from the conventional bubbling fluidized bed (BFB) to circulating fluidized bed (CFB) combustion systems. Inherent advantages of CFB combustion such as uniform temperatures, excellent mixing, high combustion efficiencies, and greater fuel flexibility have generated interest in the feasibility of CFB combustion systems applied to the thermal remediation of contaminated soils and sludges. Because it is often difficult to monitor and analyze the combustion phenomena that occurs within a full scale fluidized bed system, the need exists for smaller scale research facilities which permit detailed measurements of temperature, pressure, and chemical specie profiles. This article describes the design, construction, and operation of a pilot-scale fluidized bed facility developed to investigate the thermal remediation characteristics of contaminated soils and sludges. The refractory-lined reactor measures 8 m in height and has an external diameter of 0.6 m. The facility can be operated as a BFB or CFB using a variety of solid fuels including low calorific or high moisture content materials supplemented by natural gas introduced into the fluidized bed through auxiliary fuel injectors. Maximum firing rate of the fluidized bed is approximately 300 kW. Under normal operating conditions, internal wall temperatures are maintained between 1150 and 1350 K over superficial velocities ranging from 0.5 to 4 m/s. Contaminated material can be continuously fed into the fluidized bed or introduced as a single charge at three different locations. The facility is fully instrumented to allow time-resolved measurements of gaseous pollutant species, gas phase temperatures, and internal pressures. The facility has produced reproducible fluidization results which agree well with the work of other researchers. Minimum

  10. Predictive models of circulating fluidized bed combustors: SO[sub 2] sorption in the CFB loop

    SciTech Connect

    Gidaspow, D.; Therdthianwong, A. . Dept. of Chemical Engineering)

    1993-02-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Sorption of S0[sub 2] with calcined limestone was studied in a PYROFLOW type CFB loop at conditions approximating those found in a CFB combustor. Initially the CFB loop contained 150 micron CaO particles of a density of 3.3 g/cm[sup 3] and air at 1143[degrees]K and 3.25 atm. Atzero time, air containing 600 ppm SO[sub 2], was introduced into the riser bottom at 1143[degrees]K. The effect of gas velocity, sorbent inventory and inlet pressure on the sorption of SO[sub 2], were studied isothermally by running our hydrodynamic code with the S0[sub 2] sorption conservation of species equation. At a velocity of 5m/sec., reported to be a typical velocity by PYROPOWER, there is reasonably good S0[sub 2] removal. At 10 m/sec the S0[sub 2] removal is poor. The best SO[sub 2], removal is for a velocity of 5 m/s and a high bed inventory, initial bed height, H = 9m. Most of the S0[sub 2] is removed in the first two meters of the reactor. However, the S0[sub 2] removal is not complete at the bed outlet. This is due to mixing. At the left wall of the reactor (wall opposite the solids inlet) the S0[sub 2] removal was poor due to gas bypassing caused by the asymmetrical solids inlet. Simulation of the PYROPOWER loop with a symmetrical inlet gave us an order of magnitude improvement over the conventional PYROPOWER system. These results demonstrate the practical utility of the predictive model that we have developed over the last three years.

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

    SciTech Connect

    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 signal 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.

  12. Experimental study of the hydrodynamics and cluster formation in a Circulating Fluidized Bed. Annual report, 1990

    SciTech Connect

    Gautam, M.; Johnson, E.

    1991-01-01

    A novel non-invasive gas-solid flow measuring technique being developed and tested for studying the hydrodynamics inside the riser of a Circulating Fluidized Bed (CFB). First of the two aims of the overall program, namely, design, development and testing of the technique to characterize the particle and gas velocities in two-phase flows was accomplished in the past year. The ``fringe-model`` laser Doppler anemometry concept has been modified and extended by using particles coated with a fluorescent dye and introducing a narrow band pass filter in the receiving optics. The technique permits optical discrimination between the scattered light (laser wavelength from undyed particles) and the fluorescence emission (longer wavelength). Results from extensive testing of various dye-solvent combinations, counter processor settings, signal-to noise optimization and subsequent flow measurements in the test section have shown that the technique can effectively discriminate between two classes of particles--the smaller seed particles for the gas phase data and the larger bed particles. Use of a two-watt Argon-Ion laser assisted in the non-intrusive probing of the gas-solid flow and in enhancing the signal-to-noise ratio. An uncertainty analysis of LDA measurements is presented. Design of the cold flow CFB model, presently under fabrication, is outlined in this report. The Plexiglas CFB model will be employed for the riser core-annular flow studies using the fluorescence-emission based laser-Doppler anemometry. The results from this study will present a unique detailed description of the complex gas-solid behavior in the CFB riser.

  13. Experimental study of the hydrodynamics and cluster formation in a Circulating Fluidized Bed

    SciTech Connect

    Gautam, M.; Johnson, E.

    1991-01-01

    A novel non-invasive gas-solid flow measuring technique being developed and tested for studying the hydrodynamics inside the riser of a Circulating Fluidized Bed (CFB). First of the two aims of the overall program, namely, design, development and testing of the technique to characterize the particle and gas velocities in two-phase flows was accomplished in the past year. The fringe-model'' laser Doppler anemometry concept has been modified and extended by using particles coated with a fluorescent dye and introducing a narrow band pass filter in the receiving optics. The technique permits optical discrimination between the scattered light (laser wavelength from undyed particles) and the fluorescence emission (longer wavelength). Results from extensive testing of various dye-solvent combinations, counter processor settings, signal-to noise optimization and subsequent flow measurements in the test section have shown that the technique can effectively discriminate between two classes of particles--the smaller seed particles for the gas phase data and the larger bed particles. Use of a two-watt Argon-Ion laser assisted in the non-intrusive probing of the gas-solid flow and in enhancing the signal-to-noise ratio. An uncertainty analysis of LDA measurements is presented. Design of the cold flow CFB model, presently under fabrication, is outlined in this report. The Plexiglas CFB model will be employed for the riser core-annular flow studies using the fluorescence-emission based laser-Doppler anemometry. The results from this study will present a unique detailed description of the complex gas-solid behavior in the CFB riser.

  14. CO-PRODUCTION OF HYDROGEN AND ELECTRICITY USING PRESSURIZED CIRCULATING FLUIDIZED BED GASIFICATION TECHNOLOGY

    SciTech Connect

    Zhen Fan

    2006-05-30

    Foster Wheeler has completed work under a U.S. Department of Energy cooperative agreement to develop a gasification equipment module that can serve as a building block for a variety of advanced, coal-fueled plants. When linked with other equipment blocks also under development, studies have shown that Foster Wheeler's gasification module can enable an electric generating plant to operate with an efficiency exceeding 60 percent (coal higher heating value basis) while producing near zero emissions of traditional stack gas pollutants. The heart of the equipment module is a pressurized circulating fluidized bed (PCFB) that is used to gasify the coal; it can operate with either air or oxygen and produces a coal-derived syngas without the formation of corrosive slag or sticky ash that can reduce plant availabilities. Rather than fuel a gas turbine for combined cycle power generation, the syngas can alternatively be processed to produce clean fuels and or chemicals. As a result, the study described herein was conducted to determine the performance and economics of using the syngas to produce hydrogen for sale to a nearby refinery in a hydrogen-electricity co-production plant setting. The plant is fueled with Pittsburgh No. 8 coal, produces 99.95 percent pure hydrogen at a rate of 260 tons per day and generates 255 MWe of power for sale. Based on an electricity sell price of $45/MWhr, the hydrogen has a 10-year levelized production cost of $6.75 per million Btu; this price is competitive with hydrogen produced by steam methane reforming at a natural gas price of $4/MMBtu. Hence, coal-fueled, PCFB gasifier-based plants appear to be a viable means for either high efficiency power generation or co-production of hydrogen and electricity. This report describes the PCFB gasifier-based plant, presents its performance and economics, and compares it to other coal-based and natural gas based hydrogen production technologies.

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

    SciTech Connect

    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 CFB 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.

  16. Characterization of fly ash from a circulating fluidized bed incinerator of municipal solid waste.

    PubMed

    Zhang, Lin; Su, Xiaowen; Zhang, Zhixuan; Liu, Siming; Xiao, Yuxin; Sun, Mingming; Su, Jixin

    2014-11-01

    Treatment and disposal of fly ash in China are becoming increasingly difficult, since its production has steadily risen and its features are uncertain. The excess pollutant components of fly ash are the key factor affecting its treatment and resource utilization. In this study, fly ash samples collected from a power plant with circulating fluidized incinerators of municipal solid waste (MSW) located in Shandong Province (eastern China) were studied. The results showed that there were no obvious seasonal differences in properties of fly ash. The content of total salt, Zn, and pH exceeded the national standards and low-ring polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (Fs) were the main organic components of fly ash for this power plant, which posed great threats to the surrounding environment. The amount of Zn of fly ash was higher than other heavy metals, which should be due to alkaline batteries of MSW. The leachate of fly ash had low concentrations of heavy metals and the main soluble components were sulfates and chlorides. The major mineral crystals of fly ash were SiO2, CaSO4, and Fe2O3. The main organic pollutants were low-ring PAHs, polychlorinated PCDDs, and low-chlorinated PCDFs, and concentrations were lower than the limiting values of the national regulations. Additionally, the distribution of PCDD/Fs had either a positive or a negative linear correlation with fly ash and flue gas, which was associated with the chlorinated degree of PCDD/Fs. The analysis was conducted to fully understand the properties of fly ash and to take appropriate methods for further comprehensive utilization.

  17. 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

  18. Experimental study on combustion characteristics and NOX emissions of pulverized anthracite preheated by circulating fluidized bed

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Zhu, Jian-Guo; Lu, Qing-Gang

    2011-08-01

    A 30 kW bench-scale rig of pulverized anthracite combustion preheated by a circulating fluidized bed (CFB) was developed. The CFB riser has a diameter of 90 mm and a height of 1,500 mm. The down-fired combustion chamber (DFCC) has a diameter of 260 mm and a height of 3,000 mm. Combustion experiments were carried out using pulverized anthracite with 6.74% volatile content. This low volatile coal is difficult to ignite and burn out. Therefore, it requires longer burnout time and higher combustion temperature, which results in larger NOX emissions. In the current study, important factors that influence the combustion characteristics and NOX emissions were investigated such as excess air ratio, air ratio in the reducing zone, and fuel residence time in the reducing zone. Pulverized anthracite can be quickly preheated up to 800°C in CFB when the primary air is 24% of theoretical air for combustion, and the temperature profile is uniform in DFCC. The combustion efficiency is 94.2%, which is competitive with other anthracite combustion technologies. When the excess air ratio ranges from 1.26 to 1.67, the coal-N conversion ratio is less than 32% and the NOX emission concentration is less than 371 mg/m3 (@6% O2). When the air ratio in the reducing zone is 0.12, the NOX concentration is 221 mg/m3 (@6% O2), and the coal-N conversion ratio is 21%, which is much lower than that of other boilers.

  19. Influence of chemical and thermodynamic parameters on the flue gas desulphurization efficiency in a circulating fluidized bed

    NASA Astrophysics Data System (ADS)

    Fan, Baoguo; You, Changfu; Qi, Haiying; Xiang, Guangming; Xu, Xuchang

    2001-07-01

    An experimental study has been performed systematically on flue gas desulphurization by using circulating fluidized bed. The relationship, between desulphurization efficiency and the parameters of thermodynamics and chemistry, was investigated basically. It is shown that the bed temperature and the vapor partial pressure in the bed are the important parameters that influence the desulphurization efficiency. The closer the bed temperature to the dew point and the higher the vapor partial pressure, the higher is the desulphurization efficiency. With increasing of Ca/S, the desulphurization efficiency ascends. Comparing with different operating methods, the optimum method has been found.

  20. A circulating fluidized-bed furnace for combusting anthracite culm and the thermal-contact pyrolysis of coal

    NASA Astrophysics Data System (ADS)

    Rokhman, B. B.

    2007-09-01

    A method for thermal-contact pyrolysis of coal and a furnace design for combusting solid fuel in a circulating fluidized bed are proposed. The geometric, aerodynamic, and physicochemical parameters of the pyrolysis zone situated in the near-wall region of the freeboard space are calculated. It is shown that, if the initial fuel is fed through a part of the annular zone’s cross-sectional area, the near-wall clusters are destroyed and the concentration of the dispersed phase in the reaction zone increases, both resulting in the thermochemical processing of recirculating coke-ash particles to proceed more rapidly.

  1. Processing of residues and municipal waste in circulating fluidized beds: Operating experience, design concepts and future developments

    SciTech Connect

    Plass, L.; Albrecht, J.; Loeffler, J.C.

    1997-12-31

    Based on experience on processing of unconventional fuels in commercial Circulating Fluidized Bed (CFB) gasifiers new plant concepts for thermal treatment of residues and municipal waste are presented. Particular emphasis is put on optimizing process efficiencies and environmental performance of the overall processes. The thermal treatment of waste is carried out in two steps: Gasification in a CFB-reactor is followed by a high temperature reactor for complete breakdown of gaseous condensable hydrocarbons and for slagging of dust entrained in the CFB product gas. Major details of the process alternatives are discussed in view of economical and ecological aspects.

  2. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    SciTech Connect

    Wei-Ping Pan; Yan Cao; John Smith

    2008-05-31

    On February 14, 2002, President Bush announced the Clear Skies Initiative, a legislative proposal to control the emissions of nitrogen oxides (NO{sub x}), sulfur dioxide (SO{sub 2}), and mercury from power plants. In response to this initiative, the National Energy Technology Laboratory organized a Combustion Technology University Alliance and hosted a Solid Fuel Combustion Technology Alliance Workshop. The workshop identified multi-pollutant control; improved sorbents and catalysts; mercury monitoring and capture; and improved understanding of the underlying reaction chemistry occurring during combustion as the most pressing research needs related to controlling environmental emissions from fossil-fueled power plants. The Environmental Control Technology Laboratory will help meet these challenges and offer solutions for problems associated with emissions from fossil-fueled power plants. The goal of this project was to develop the capability and technology database needed to support municipal, regional, and national electric power generating facilities to improve the efficiency of operation and solve operational and environmental problems. In order to effectively provide the scientific data and the methodologies required to address these issues, the project included the following aspects: (1) Establishing an Environmental Control Technology Laboratory using a laboratory-scale, simulated fluidized-bed combustion (FBC) system; (2) Designing, constructing, and operating a bench-scale (0.6 MW{sub th}), circulating fluidized-bed combustion (CFBC) system as the main component of the Environmental Control Technology Laboratory; (3) Developing a combustion technology for co-firing municipal solid waste (MSW), agricultural waste, and refuse-derived fuel (RDF) with high sulfur coals; (4) Developing a control strategy for gaseous emissions, including NO{sub x}, SO{sub 2}, organic compounds, and heavy metals; and (5) Developing new mercury capturing sorbents and new

  3. JV Task 108 - Circulating Fluidized-Bed Combustion and Combustion Testing of Turkish Tufanbeyli Coal

    SciTech Connect

    Douglas Hajicek; Jay Gunderson; Ann Henderson; Stephen Sollom; Joshua Stanislowski

    2007-08-15

    Two combustion tests were performed at the Energy & Environmental Research Center (EERC) using Tufanbeyli coal from Turkey. The tests were performed in a circulating fluidized-bed combustor (CFBC) and a pulverized coal-fired furnace, referred to as the combustion test facility (CTF). One of the goals of the project was to determine the type of furnace best suited to this coal. The coal is high in moisture, ash, and sulfur and has a low heating value. Both the moisture and the sulfur proved problematic for the CTF tests. The fuel had to be dried to less than 37% moisture before it could be pulverized and further dried to about 25% moisture to allow more uniform feeding into the combustor. During some tests, water was injected into the furnace to simulate the level of flue gas moisture had the fuel been fed without drying. A spray dryer was used downstream of the baghouse to remove sufficient sulfur to meet the EERC emission standards permitted by the North Dakota Department of Health. In addition to a test matrix varying excess air, burner swirl, and load, two longer-term tests were performed to evaluate the fouling potential of the coal at two different temperatures. At the lower temperature (1051 C), very little ash was deposited on the probes, but deposition did occur on the walls upstream of the probe bank, forcing an early end to the test after 2 hours and 40 minutes of testing. At the higher temperature (1116 C), ash deposition on the probes was significant, resulting in termination of the test after only 40 minutes. The same coal was burned in the CFBC, but because the CFBC uses a larger size of material, it was able to feed this coal at a higher moisture content (average of 40.1%) compared to the CTF (ranging from 24.2% to 26.9%). Sulfur control was achieved with the addition of limestone to the bed, although the high calcium-to-sulfur rate required to reduce SO{sub 2} emissions resulted in heat loss (through limestone calcination) and additional ash

  4. Particle-size optimization for SO{sub 2} capture by limestone in a circulating fluidized bed

    SciTech Connect

    Saastamoinen, J.J.

    2007-10-15

    Sulfur capture by limestone particles in a circulating fluidized bed is studied by modeling. Small particles are reactive but they have a short residence time depending on the separation efficiency of the cyclone. With large particles, the residence time is longer, but the rate and degree of sulfur capture are lower. Then the large particles removed in the bottom ash flow may have reached a lesser degree of conversion (from CaO to CaSO{sub 4}), especially if the rate of attrition is low. The optimum particle size or particle-size distribution to minimize the limestone feed rate to achieve a given efficiency of sulfur capture is discussed. A methodology to calculate the optimum size is presented.

  5. A novel fluidized bed respirometric technique for determination of in situ biofilm kinetics.

    PubMed

    Chowdhury, Nabin; Nakhla, George; Zhu, Jesse

    2012-01-01

    A respirometric approach has been developed to determine heterotrophic biofilm kinetics using fluidized bioparticles--particles with attached biomass. Lava rock particles of 600 microm were used as a biomass carrier medium. The modified respirometer successfully estimates in situ biofilm kinetics of the bioparticles collected from a pilot-scale liquid-solid circulating fluidized bed (LSCFB) bioreactor. The observed maximum specific growth rates (micro(max)) of 3.69 +/- 0.44 d(-1) and biomass yields (Y(H)) of 0.36 +/- 0.03 g COD/g COD in the fluidized bed respirometers were significantly different from the micro(max) of 5.57-5.72 d(-1) and Y(H) of 0.54-0.59 g COD/g COD observed in the conventional respirometric tests for bioparticles and detached biomass. The higher Monod half-saturation coefficient (K(S)) of 186-219mg COD/L observed in the fluidized bed respirometers relative to the 49-58 mg COD/L in the conventional respirometers reveals the presence of mass transfer resistance in the LSCFB despite fluidization. Significantly reduced yields in the fluidized bed respirometers and the estimated maintenance coefficient of 1.16 d(-1) for the particulate biofilm in the LSCFB clearly emphasize that a substantial amount of substrate was utilized for cell maintenance at the low food to microorganism (S/X) ratio of 0.5 g COD/g VSS.

  6. The Nucla Circulating Fluidized-Bed Demonstration Project: A U.S. DOE post-project assessment

    SciTech Connect

    1995-06-01

    This report is a post-project assessment of the Nucla Circulating Fluidized-Bed (CFB) Demonstration Project, the second project to be completed in the DOE Clean Coal Technology Program. Nucla was the first successful utility repowering project in the US, increasing the capacity of the original power station from 36 MW(e) to 110 MW(e) and extending its life by 30 years. In the CFB boiler, combustion and desulfurization both take place in the fluidized bed. Calcium in the sorbent captures sulfur dioxide and the relatively low combustion temperatures limit NOx formation. Hot cyclones separate the larger particles from the gas and recirculates them to the lower zones of the combustion chambers. This continuous circulation of coal char and sorbent particles is the novel feature of CFB technology. This demonstration project significantly advanced the environmental, operational, and economic potential of atmospheric CFB technology, precipitating a large number of orders for atmospheric CFB equipment. By 1994, more than 200 atmospheric CFB boilers have been constructed worldwide. Although at least six CFB units have been operated, the Nucla project`s CFB database continues to be an important and unique resource for the design of yet larger atmospheric CFB systems. The post-project assessment report is an independent DOE appraisal of the success a completed project had in achieving its objectives and aiding in the commercialization of the demonstrated technology. The report also provides an assessment of the expected technical, environmental, and economic performance of the commercial version of the technology as well as an analysis of the commercial market.

  7. Final Environmental Impact Statement for the JEA Circulating Fluidized Bed Combustor Project

    SciTech Connect

    N /A

    2000-06-30

    This EIS assesses environmental issues associated with constructing and demonstrating a project that would be cost-shared by DOE and JEA (formerly the Jacksonville Electric Authority) under the Clean Coal Technology Program. The project would demonstrate circulating fluidized bed (CFB) combustion technology at JEA's existing Northside Generating Station in Jacksonville, Florida, about 9 miles northeast of the downtown area of Jacksonville. The new CFB combustor would use coal and petroleum coke to generate nearly 300 MW of electricity by repowering the existing Unit 2 steam turbine, a 297.5-MW unit that has been out of service since 1983. The proposed project is expected to demonstrate emission levels of sulfur dioxide (SO{sub 2}), oxides of nitrogen (NO{sub x}), and particulate matter that would be lower than Clean Air Act limits while at the same time producing power more efficiently and at less cost than conventional coal utilization technologies. At their own risk, JEA has begun initial construction activities without DOE funding. Construction would take approximately two years and, consistent with the original JEA schedule, would be completed in December 2001. Demonstration of the proposed project would be conducted during a 2-year period from March 2002 until March 2004. In addition, JEA plans to repower the currently operating Unit 1 steam turbine about 6 to 12 months after the Unit 2 repowering without cost-shared funding from DOE. Although the proposed project consists of only the Unit 2 repowering, this EIS analyzes the Unit 1 repowering as a related action. The EIS also considers three reasonably foreseeable scenarios that could result from the no-action alternative in which DOE would not provide cost-shared funding for the proposed project. The proposed action, in which DOE would provide cost-shared finding for the proposed project, is DOE's preferred alternative. The EIS evaluates the principal environmental issues, including air quality, traffic

  8. Draft Environmental Impact Statement for the JEA Circulating Fluidized Bed Combustor Project

    SciTech Connect

    N /A

    1999-08-27

    This EIS assesses environmental issues associated with constructing and demonstrating a project that would be cost-shared by DOE and JEA (formerly the Jacksonville Electric Authority) under the Clean Coal Technology Program. The project would demonstrate circulating fluidized bed (CFB) combustion technology at JEA's existing Northside Generating Station in Jacksonville, Florida, which occupies a 400-acre industrial site along the north shore of the St. Johns River about 9 miles northeast of the downtown area of Jacksonville. The new CFB combustor would use coal and petroleum coke to generate nearly 300 MW of electricity by repowering the existing Unit 2 steam turbine, a 297.5-MW unit that has been out of service since 1983. The proposed project is expected to demonstrate emission levels of sulfur dioxide (SO{sub 2}), oxides of nitrogen (NO{sub x}), and particulate matter that would be lower than Clean Air Act limits while at the same time producing power more efficiently and at less cost than conventional coal utilization technologies. JEA has indicated that construction may begin without DOE funding prior to the completion of the NEPA process in February 2000 and would continue until December 2001. Demonstration of the proposed project would be conducted during a 2-year period from March 2002 until March 2004. In addition, JEA plans to repower the currently operating Unit 1 steam turbine about 6 to 12 months after the Unit 2 repowering without cost-shared funding from DOE. Although the proposed project consists of only the Unit 2 repowering, this EIS analyzes the Unit 1 repowering as a related action. The EIS also considers three reasonably foreseeable scenarios that could result from the no-action alternative in which DOE would not provide cost-shared funding for the proposed project. The proposed action, in which DOE would provide cost-shared funding for the proposed project, is DOE's preferred alternative. The EIS evaluates the principal environmental issues

  9. An experimental study of the hydrodynamics and cluster formation in a circulating fluidized bed. Topical report, January 1, 1991--June 30, 1992

    SciTech Connect

    Gautam, M.; Jurewicz, J.; Heping, Y.; Clifton, K.

    1992-07-01

    This research program involves two major aspects. First, to evaluate techniques to effectively probe the polydisperse gas-solid flows and second, to apply these techniques to study the gas-solid flow structure and clusters in the riser of a circulating fluidized bed riser. Amongst the non-intrusive techniques a modified laser Doppler technique based on the fluorescence-emission concept has been adopted and the other techniques involve pitot-static pressure probes. A circulating fluidized bed (CFB) facility has been designed, built and is currently operational at West Virginia University. The design provides for maximum versatility in investigating the hydrodynamics of the CFB riser. Two stage cyclones are employed to capture the particles exhausted from the riser. Measurements of gas velocity distribution were carried out in the circulating fluidized bed riser. with particles having a mean diameter of 112 {mu}m and a density of 2305 kg/m{sup 3} and another set of particles with a mean diameter of 145 {mu}m and a density of 2245 kg/m{sup 3}. The experimental results showed that the local gas velocity varied with the radial position, elevation, solids circulation rate, superficial velocity and particle size. A general formula for gas velocity distribution in the circulating fluidized bed riser was obtained based on the particle circulation, superficial velocity and particle diameter. The pressure drops across the L-valve were also studied for different particle sizes, L-valve diameters and aeration. The solids flowrate was found to be a function of the L-valve geometry, operating parameters and solids properties. Pressure drop of L-valve increases with increasing solids diameter and decreasing diameter of the L-valve. Pressure drop across standpipe increases as the solids diameter and diameter of the standpipe decrease.

  10. 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.

  11. Innovative method using magnetic particle tracking to measure solids circulation in a spouted fluidized bed

    SciTech Connect

    Patterson, Ms. Emily; Halow, John; Daw, C Stuart

    2009-01-01

    We describe an innovative method for measuring particle motion inside spouted fluidized beds. The method uses a magnetic tracer particle, which follows the bulk particle flow and is continuously tracked by multiple magnetic field detectors located outside the bed. We analyze signals from the detectors to determine the tracer position at each instant in time. From statistical analysis of the tracer trajectory, characteristic measures of the bulk particle flow, such as the average recirculation frequency, can be determined as a function of operating conditions. For experiments with a range of particle sizes and densities in a 3.9-cm-diameter spouted bed, we find that average solids recirculation rates correlate with excess velocity (superficial minus minimum spouting velocity), particle density, and bed depth.

  12. Experimental study on structural optimization of a supercritical circulating fluidized bed boiler with an annular furnace and six cyclones

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofang; Shuai, Daping; Lyu, Qinggang

    2017-10-01

    Annular furnace CFBs with six cyclones represent new designs for large capacity CFB boilers over 660 MW. To investigate the gas-solid flow non-uniformity and its main influencing factors, an experimental study was carried out in the cold-test rig of an annular furnace CFB with six cyclones. The influence of furnace structure and cyclone arrangement on the non-uniformity of gas-solid flow was obtained. On the basis of these findings, the structure of the annular furnace CFB with six cyclones was optimized, and an optimal structure was obtained. The results show that for newly designed annular furnace CFBs, the non-uniformity of gas-solid flow among loops is no greater than that of traditional CFBs. In terms of uniformity, side cyclones rotating inward are superior to those rotating outward. The position of the side cyclones determines the basic solid circulating rate distribution trend and can dramatically improve flow non-uniformity. The middle cyclone positions and the symmetric modes of the cyclones do not determine the solid circulating rate distribution trend and have less effect on DEV Gs. Forty-five degree chamfers of outer ring walls can reduce wall erosion and the non-uniformity of gas-solid flow in the circulating fluidized bed. Regarding the operating and structural conditions in this work, the optimal structure of annular furnace CFBs is Type 6: side cyclones rotating inward and b = a/2, d = 0.1 c; the center of the middle cyclone inlet located at the centerline of the furnace cross-section; cyclones on the two sides of the furnace in an axisymmetric arrangement; and a furnace corner shape of 45° chamfers. Under the given operating conditions, the DEV Gs for the optimal structure are approximately 4.0% 10.3%.

  13. Conceptual design and assessment of a pressurized circulating fluidized-bed boiler. Final report

    SciTech Connect

    Matthews, F.T.; Payne, H.M.; Wechsler, A.T.; Saunders, W.H.; Berman, P.A.; Dille, J.C.

    1983-12-01

    This report presents a technical feasibility study of a turbocharged boiler employing a Lurgi circulating fluid bed combustion system operating at 10 atmospheres pressure. The study is based on a 250 MW(e) plant firing a high sulfur Illinois No. 6 bituminous coal. The basic design objective was to develop a plant with components that can be shop-assembled and transported to the plant site by barge on the nation's inland waterways. The study was jointly undertaken by Combustion Engineering, Inc., Lurgi Corporation, and Westinghouse Electric Corporation and included development of design parameters, a conceptual design and general arrangement, a control philosophy, and identification of areas where further development is needed. The methods utilized to determine the feasibility of the pressurized circulating fluid bed system and to develop system concepts were based on Lurgi's extensive experience in atmospheric circulating fluid bed technology. The system consists of the same components as used in an atmospheric circulating fluid bed system, but designed for operation at 10 atmospheres. The principal conclusions of the study are that the concept of burning coal in a circulating fluid bed can be applied to a system operating at 10 atmospheres, that shop fabrication can be maximized, and the system components can be barge shipped. The conclusions also indicate that this concept is a viable method for providing incremental steam generating capacity either in existing plants or in first generation steam plants.

  14. Comparison of ANN (MLP), ANFIS, SVM, and RF models for the online classification of heating value of burning municipal solid waste in circulating fluidized bed incinerators.

    PubMed

    You, Haihui; Ma, Zengyi; Tang, Yijun; Wang, Yuelan; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa; Huang, Qunxing

    2017-04-10

    The heating values, particularly lower heating values of burning municipal solid waste are critically important parameters in operating circulating fluidized bed incineration systems. However, the heating values change widely and frequently, while there is no reliable real-time instrument to measure heating values in the process of incinerating municipal solid waste. A rapid, cost-effective, and comparative methodology was proposed to evaluate the heating values of burning MSW online based on prior knowledge, expert experience, and data-mining techniques. First, selecting the input variables of the model by analyzing the operational mechanism of circulating fluidized bed incinerators, and the corresponding heating value was classified into one of nine fuzzy expressions according to expert advice. Development of prediction models by employing four different nonlinear models was undertaken, including a multilayer perceptron neural network, a support vector machine, an adaptive neuro-fuzzy inference system, and a random forest; a series of optimization schemes were implemented simultaneously in order to improve the performance of each model. Finally, a comprehensive comparison study was carried out to evaluate the performance of the models. Results indicate that the adaptive neuro-fuzzy inference system model outperforms the other three models, with the random forest model performing second-best, and the multilayer perceptron model performing at the worst level. A model with sufficient accuracy would contribute adequately to the control of circulating fluidized bed incinerator operation and provide reliable heating value signals for an automatic combustion control system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Dynamic simulation of a circulating fluidized bed boiler of low circulating ratio with wide particle size distributions

    SciTech Connect

    Lu Huilin; Yang Lidan; Bie Rushan; Zhao Guangbo

    1999-07-01

    A steady state model of a coal fired CFB boiler considering the hydrodynamics, heat transfer and combustion is presented. This model predicts the flue gas temperature, the chemical gas species (O{sub 2}, H{sub 2}O, CO, CO{sub 2} and SO{sub 2}) and char concentration distributions in both the axial and radial location along the furnace including the bottom and upper portion. The model was validated against experimental data generated in a 35 t/h commercial CFB boiler with low circulating ratio.

  16. 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.

  17. Circulating fluidized bed combustion product addition to acid soil: alfalfa (Medicago sativa L.) composition and environmental quality.

    PubMed

    Chen, Liming; Dick, Warren A; Kost, David

    2006-06-28

    To reduce S emissions, petroleum coke with a high concentration of S was combusted with limestone in a circulating fluidized bed (CFB) boiler. The combustion process creates a bed product that has potential for agricultural uses. This CFB product is often alkaline and enriched in S and other essential plant nutrients, but also contains high concentrations of Ni and V. Agricultural land application of CFB product is encouraged, but little information is available related to plant responses and environmental impacts. CFB product and agricultural lime (ag-lime) were applied at rates of 0, 0.5, 1.0, and 2.0 times the soil's lime requirement (LR) to an acidic soil (Wooster silt loam). The 2.0x LR application rate of CFB product was equivalent to 67.2 Mg ha(-1). Alfalfa yield was increased 4.6 times by CFB product and 3.8 times by ag-lime compared to untreated control. Application of CFB product increased the concentration of V in soil and alfalfa tissue, but not in soil water, and increased the concentration of Ni in soil and soil water, but not in alfalfa tissue. However, these concentrations did not reach levels that might cause environmental problems.

  18. SO{sub x} and NO{sub x} control in Pyroflow circulating fluidized-bed boilers

    SciTech Connect

    Ganesh, A.; Johnk, C.

    1995-12-31

    Ahlstrom Pyropower offers the most comprehensive experience with Circulating Fluidized-Bed Boiler technology available in the world. There are more than 135 Pyroflow units in operation or under construction worldwide with over 400 unit years of operating experience. All Ahlstrom Pyropower units have met their guarantees including, in some cases, the strictest emission limits. Pyroflow commercial CFB boilers have proven the ability and flexibility to burn a wide variety of low grade fuels economically and still meet stringent environmental requirements. The emission control in CFB boilers is specific to the type of fuel used, since each fuel analysis can vary widely. Sulfur dioxide emissions (SO{sub 2}) from CFB boilers are effectively controlled by means of feeding limestone at predetermined locations in the furnace. NO{sub x} emissions are controlled by staged combustion. NO{sub x} emissions can be controlled furthermore by direct injection of ammonia or urea at furnace outlet. SO{sub 2} and NO{sub x} emissions in Ahlstrom Pyropower CFB boilers have been improved over the years by improved process and design parameters. Data from recently commissioned units are provided. A comparison of SO{sub 2} and NO{sub x} emissions with permitted levels is made.

  19. 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.

  20. Combustion characteristics of paper mill sludge in a lab-scale combustor with internally cycloned circulating fluidized bed.

    PubMed

    Shin, D; Jang, S; Hwang, J

    2005-01-01

    After performing a series of batch type experiments using a lab-scale combustor, consideration was given to the use of an internally cycloned circulating fluidized bed combustor (ICCFBC) for a paper mill sludge. Operation parameters including water content, feeding mass of the sludge, and secondary air injection ratio were varied to understand their effects on combustion performance, which was examined in terms of carbon conversion rate (CCR) and the emission rates of CO, C(x)H(y) and NO(x). The combustion of paper mill sludge in the ICCFBC was compared to the reaction mechanisms of a conventional solid fuel combustion, characterized by kinetics limited reaction zone, diffusion limited reaction zone, and transition zone. The results of the parametric study showed that a 35% water content and 60 g feeding mass generated the best condition for combustion. Meanwhile, areal mass burning rate, which is an important design and operation parameter at an industrial scale plant, was estimated by a conceptual equation. The areal mass burning rate corresponding to the best combustion condition was approximately 400 kg/hm(2) for 35% water content. The secondary air injection generating swirling flow enhanced the mixing between the gas phase components as well as the solid phase components, and improved the combustion efficiency by increasing the carbon conversion rate and reducing pollutant emissions.

  1. Effect of cofiring coal and biofuel with sewage sludge on alkali problems in a circulating fluidized bed boiler

    SciTech Connect

    K.O. Davidsson; L.-E. Aamand; A.-L. Elled; B. Leckner

    2007-12-15

    Cofiring experiments were performed in a 12 MW circulating fluidized bed boiler. The fuel combinations were biofuel (wood+straw), coal+biofuel, coal+sewage sludge+biofuel, and sewage sludge+biofuel. Limestone or chlorine (PVC) was added in separate experiments. Effects of feed composition on bed ash and fly ash were examined. The composition of flue gas was measured, including on-line measurement of alkali chlorides. Deposits were collected on a probe simulating a superheater tube. It was found that the fuel combination, as well as addition of limestone, has little effect on the alkali fraction in bed ash, while chlorine decreases the alkali fraction in bed ash. Sewage sludge practically eliminates alkali chlorides in flue gas and deposits. Addition of enough limestone to coal and sludge for elimination of the SO{sub 2} emission does not change the effect of chlorine. Chlorine addition increases the alkali chloride in flue gas, but no chlorine was found in the deposits with sewage sludge as a cofuel. Cofiring of coal and biofuel lowers the alkali chloride concentration in the flue gas to about a third compared with that of pure biofuel. This is not affected by addition of lime or chlorine. It is concluded that aluminum compounds in coal and sludge are more important than sulfur to reduce the level of KCl in flue gas and deposits. 24 refs., 8 figs., 7 tabs.

  2. 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

  3. A Study on Methane and Nitrous Oxide Emissions Characteristics from Anthracite Circulating Fluidized Bed Power Plant in Korea

    PubMed Central

    Lee, Seehyung; Kim, Jinsu; Lee, Jeongwoo; Jeon, Eui-Chan

    2012-01-01

    In order to tackle climate change effectively, the greenhouse gas emissions produced in Korea should be assessed precisely. To do so, the nation needs to accumulate country-specific data reflecting the specific circumstances surrounding Korea's emissions. This paper analyzed element contents of domestic anthracite, calorific value, and concentration of methane (CH4) and nitrous oxide (N2O) in the exhaust gases from circulating fluidized bed plant. The findings showed the concentration of CH4 and N2O in the flue gas to be 1.85 and 3.25 ppm, respectively, and emission factors were 0.486 and 2.198 kg/TJ, respectively. The CH4 emission factor in this paper was 52% lower than default emission factor presented by the IPCC. The N2O emission factor was estimated to be 46% higher than default emission factor presented by the IPCC. This discrepancy can be attributable to the different methods and conditions of combustion because the default emission factors suggested by IPCC take only fuel characteristics into consideration without combustion technologies. Therefore, Korea needs to facilitate research on a legion of fuel and energy consumption facilities to develop country-specific emission factors so that the nation can have a competitive edge in the international climate change convention in the years to come. PMID:22666126

  4. A study on methane and nitrous oxide emissions characteristics from anthracite circulating fluidized bed power plant in Korea.

    PubMed

    Lee, Seehyung; Kim, Jinsu; Lee, Jeongwoo; Jeon, Eui-Chan

    2012-01-01

    In order to tackle climate change effectively, the greenhouse gas emissions produced in Korea should be assessed precisely. To do so, the nation needs to accumulate country-specific data reflecting the specific circumstances surrounding Korea's emissions. This paper analyzed element contents of domestic anthracite, calorific value, and concentration of methane (CH₄) and nitrous oxide (N₂O) in the exhaust gases from circulating fluidized bed plant. The findings showed the concentration of CH₄ and N₂O in the flue gas to be 1.85 and 3.25 ppm, respectively, and emission factors were 0.486 and 2.198 kg/TJ, respectively. The CH₄ emission factor in this paper was 52% lower than default emission factor presented by the IPCC. The N₂O emission factor was estimated to be 46% higher than default emission factor presented by the IPCC. This discrepancy can be attributable to the different methods and conditions of combustion because the default emission factors suggested by IPCC take only fuel characteristics into consideration without combustion technologies. Therefore, Korea needs to facilitate research on a legion of fuel and energy consumption facilities to develop country-specific emission factors so that the nation can have a competitive edge in the international climate change convention in the years to come.

  5. 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.

  6. Hydrodynamics in a circulating fluidized bed with annular furnace and six parallel cyclones

    NASA Astrophysics Data System (ADS)

    Shuai, Daping; Wang, Xiaofang; Lyu, Qinggang

    2017-06-01

    Systematic measurements were conducted on a cold CFB with annular furnace and six parallel cyclones to study gas-solids flow in the annular furnace and flow non-uniformity among six cyclones. The results show that axial solids holdup in the annular furnace decreases exponentially with height, similar to the conventional rectangular furnace. The uniform transverse distribution of solids holdup suggests a good gas-solids mixing in the annular furnace. The annular furnace presents the core/double-annulus flow structure, and it results in enhanced gas-solids back-mixing than the conventional core/annulus flow structure. The gas-solids flow of the inner wall-layer and the outer wall-layer is very close at most part of the furnace height, and the wall-layer thickness decreases with height. Flow non-uniformity exists among six parallel cyclones in the annular furnace CFB. But non-uniform distribution of solids circulating rates and cyclone pressure drops show no regularity, and the flow non-uniformity is no larger than the CFBs with conventional furnace. Under typical operating conditions, the relative deviation of six solids circulating rates is 8.0%.

  7. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; Douglas Donovan; John Gaudlip; Matthew Lapinsky; William Serencsits

    2001-01-18

    The Pennsylvania State University, under contract to the U.S. Department of Energy, National Energy Technology Laboratory is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute, Office of Physical Plant, and College of Agricultural Sciences; Foster Wheeler Energy Services, Inc.; Parsons Energy and Chemicals Group, Inc.; and Cofiring Alternatives. During this reporting period, work focused on performing the design of the conceptual fluidized bed system and determining the system economics.

  8. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; Douglas Donovan; John Gaudlip; Matthew Lapinsky; William Serencsits; Neil Raskin; Dale Lamke

    2001-07-13

    The Pennsylvania State University, under contract to the U.S. Department of Energy, National Energy Technology Laboratory is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute, Office of Physical Plant, and College of Agricultural Sciences, Foster Wheeler Energy Services, Inc., Parsons Energy and Chemicals Group, Inc., and Cofiring Alternatives. During this reporting period, work focused on completing the biofuel characterization and the design of the conceptual fluidized bed system.

  9. Predictive models of circulating fluidized bed combustors: SO{sub 2} sorption in the CFB loop. Fourteenth technical progress report

    SciTech Connect

    Gidaspow, D.; Therdthianwong, A.

    1993-02-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Sorption of S0{sub 2} with calcined limestone was studied in a PYROFLOW type CFB loop at conditions approximating those found in a CFB combustor. Initially the CFB loop contained 150 micron CaO particles of a density of 3.3 g/cm{sup 3} and air at 1143{degrees}K and 3.25 atm. Atzero time, air containing 600 ppm SO{sub 2}, was introduced into the riser bottom at 1143{degrees}K. The effect of gas velocity, sorbent inventory and inlet pressure on the sorption of SO{sub 2}, were studied isothermally by running our hydrodynamic code with the S0{sub 2} sorption conservation of species equation. At a velocity of 5m/sec., reported to be a typical velocity by PYROPOWER, there is reasonably good S0{sub 2} removal. At 10 m/sec the S0{sub 2} removal is poor. The best SO{sub 2}, removal is for a velocity of 5 m/s and a high bed inventory, initial bed height, H = 9m. Most of the S0{sub 2} is removed in the first two meters of the reactor. However, the S0{sub 2} removal is not complete at the bed outlet. This is due to mixing. At the left wall of the reactor (wall opposite the solids inlet) the S0{sub 2} removal was poor due to gas bypassing caused by the asymmetrical solids inlet. Simulation of the PYROPOWER loop with a symmetrical inlet gave us an order of magnitude improvement over the conventional PYROPOWER system. These results demonstrate the practical utility of the predictive model that we have developed over the last three years.

  10. 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.

  11. Stearic acid coating on circulating fluidized bed combustion fly ashes and its effect on the mechanical performance of polymer composites

    NASA Astrophysics Data System (ADS)

    Yao, Nina; Zhang, Ping; Song, Lixian; Kang, Ming; Lu, Zhongyuan; Zheng, Rong

    2013-08-01

    The aim of this work was to test circulating fluidized bed combustion fly ashes (CFAs) for its potential to be utilized in polymer composites manufacturing to improve its toughness. CFAs was coated by stearic acid and used in the composite of polypropylene/ethylene vinyl acetate/high density polyethylene (PP/EVA/HDPE) by molding process method. The resulting coated and uncoated CFAs were fully characterized by particle size analyzer, contact angles, powder X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stearic acid coated onto the surface of CFAs particles in the physical and chemical ways, and the total clad ratio reached 2.05% by measuring TGA/DTA curve. The percentage of CFAs particles focused to a narrow range 2-4 μm and the median mean size was 3.2 μm more than uncoated CFAs. The properties of hydrophobic and dispersive of CFAs particles improved and original activity was reserved after stearic acid coating. The stearic acid was verified as a coupling agent by how much effect it had on the mechanical properties. It showed the elongation at break of PP/EVA/HDPE reinforced with 15 wt% coated CFAs (c-CFAs) was 80.20% and higher than that of the uncoated. The stearic acid treatment of CFAs is a very promising approach to improve the mechanical strength due to the incorporation of stearic acid on the CFAs surface, and hence, further enhances the potential for recycling CFAs as a suitable filler material in polymer composites.

  12. Performance Improvement of 235 MWe and 260 MWe Circulating Fluidized Bed Boilers

    NASA Astrophysics Data System (ADS)

    Nowak, W.; Walkowiak, R.; Oztmowskt, T.; Jablonskr, J.; Trybala S, T.

    This article presents the results of studies on the operational performance of the first 235 MWe with hot cyclones and 260 MWe second-generation Compact circulating fluidised bed (CFB) boiler installed as part of the repowering of the Turow power plant in Poland with close to 1,500 MWe of new capacity based on CFB technology. The main characteristic distinguishing the second generation type of boiler is the use of an integrated solids separator rather than an external cyclone. The analysis of flue gas emissions showed that the standards relating to permissible concentrations of pollutants such as SO2, NOx and CO, have been met. SO2 levels have ranged from 157 mg/mn3 to 400 mg/mmn3, levels of NOx' from 120 mg/mmn3 to 342 mg/mmn3, and levels of CO from 7 to 45 mg/mmn3. The second-generation CFB boilers at the Turow power plant represent a major advance in CFB technology at this size. Studies on actual emissions indicated that the present standard related to permissible concentration of gas emissions and dust in flue gases have been met. The paper addresses also some performance improvements of the CFB boilers. In the boilers with external cyclones, erosion problems emerged after a time of 50 thousand hours. The problems have been quite precisely diagnosed recently and will be resolved on the occasion of the nearest shutdowns for major repairs.

  13. 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

  14. 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.

  15. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; John Gaudlip; Matthew Lapinsky; Rhett McLaren; William Serencsits; Neil Raskin; Tom Steitz; Joseph J. Battista

    2003-03-26

    The Pennsylvania State University, utilizing funds furnished by the U.S. Department of Energy's Biomass Power Program, investigated the installation of a state-of-the-art circulating fluidized bed boiler at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring biofuels and coal-based feedstocks. The study was performed using a team that included personnel from Penn State's Energy Institute, Office of Physical Plant, and College of Agricultural Sciences; Foster Wheeler Energy Services, Inc.; Foster Wheeler Energy Corporation; Parsons Energy and Chemicals Group, Inc.; and Cofiring Alternatives. The activities included assessing potential feedstocks at the University Park campus and surrounding region with an emphasis on biomass materials, collecting and analyzing potential feedstocks, assessing agglomeration, deposition, and corrosion tendencies, identifying the optimum location for the boiler system through an internal site selection process, performing a three circulating fluidized bed (CFB) boiler design and a 15-year boiler plant transition plan, determining the costs associated with installing the boiler system, developing a preliminary test program, determining the associated costs for the test program, and exploring potential emissions credits when using the biomass CFB boiler.

  16. Liquid/liquid/solid contact angles

    NASA Astrophysics Data System (ADS)

    Borocco, Marine; Pellet, Charlotte; Authelin, Jean-René; Clanet, Christophe; Quéré, David; Compagnie des Interfaces Team

    2016-11-01

    Many studies have investigated solid/liquid/air interfaces and their corresponding wetting properties. We discuss what happens in less-studied liquid/liquid/solid systems, and focus on questions of dynamical wetting in a tube, having in mind applications in detergency. We use a capillary tube filled with water and containing a slug of silicone oil (or vice-versa), and present a series of experiments to determine static and dynamic wetting properties corresponding to this situation. We also discuss interfacial aging of such systems.

  17. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; Douglas Donovan; John Gaudlip; Matthew Lapinsky; William Serencsits; Neil Raskin; Dale Lamke; Joseph J. Battista

    2001-03-31

    The Pennsylvania State University, under contract to the U.S. Department of Energy (DOE), National Energy Technology Laboratory (NETL) is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed (CFB) boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. Penn State currently operates an aging stoker-fired steam plant at its University Park campus and has spent considerable resources over the last ten to fifteen years investigating boiler replacements and performing life extension studies. This effort, in combination with a variety of agricultural and other wastes generated at the agricultural-based university and the surrounding rural community, has led Penn State to assemble a team of fluidized bed and cofiring experts to assess the feasibility of installing a CFB boiler for cofiring biomass and other wastes along with coal-based fuels. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute and the Office of Physical Plant, Foster Wheeler Energy Services, Inc., and Cofiring Alternatives.

  18. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; Douglas Donovan; John Gaudlip; Matthew Lapinsky; William Serencsits; Neil Raskin; Tom Steitz

    2002-07-12

    The Pennsylvania State University, under contract to the U.S. Department of Energy (DOE), National Energy Technology Laboratory (NETL) is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed (CFB) boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. Penn State currently operates an aging stoker-fired steam plant at its University Park campus and has spent considerable resources over the last ten to fifteen years investigating boiler replacements and performing life extension studies. This effort, in combination with a variety of agricultural and other wastes generated at the agricultural-based university and the surrounding rural community, has led Penn State to assemble a team of fluidized bed and cofiring experts to assess the feasibility of installing a CFB boiler for cofiring biomass and other wastes along with coal-based fuels. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute, Office of Physical Plant, and College of Agricultural Sciences; Foster Wheeler Energy Services, Inc.; Parsons Energy and Chemicals Group, Inc.; and Cofiring Alternatives.

  19. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; Douglas Donovan; John Gaudlip; Matthew Lapinsky; William Serencsits; Neil Raskin; Dale Lamke

    2001-10-12

    The Pennsylvania State University, under contract to the U.S. Department of Energy (DOE), National Energy Technology Laboratory (NETL) is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed (CFB) boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. Penn State currently operates an aging stoker-fired steam plant at its University Park campus and has spent considerable resources over the last ten to fifteen years investigating boiler replacements and performing life extension studies. This effort, in combination with a variety of agricultural and other wastes generated at the agricultural-based university and the surrounding rural community, has led Penn State to assemble a team of fluidized bed and cofiring experts to assess the feasibility of installing a CFB boiler for cofiring biomass and other wastes along with coal-based fuels.

  20. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Curtis Jawdy

    2000-10-09

    The Pennsylvania State University, under contract to the US Department of Energy, National Energy Technology Laboratory is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal or coal refuse, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute and the Office of Physical Plant, Foster Wheeler Energy Corporation, Foster Wheeler Development Corporation, and Cofiring Alternatives. The major emphasis of work during this reporting period was to assess the types and quantities of potential feedstocks and collect samples of them for analysis. Approximately twenty different biomass, animal waste, and other wastes were collected and analyzed.

  1. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    SciTech Connect

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; Douglas Donovan; John Gaudlip; Matthew Lapinsky; William Serencsits; Neil Raskin; Tom Steitz

    2002-10-14

    The Pennsylvania State University, under contract to the U.S. Department of Energy, National Energy Technology Laboratory is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute, Office of Physical Plant, and College of Agricultural Sciences; Foster Wheeler Energy Services, Inc.; Parsons Energy and Chemicals Group, Inc.; and Cofiring Alternatives. During this reporting period, the final technical design and cost estimate were submitted to Penn State by Foster Wheeler. In addition, Penn State initiated the internal site selection process to finalize the site for the boiler plant.

  2. Application of an internally circulating fluidized bed for windowed solar chemical reactor with direct irradiation of reacting particles - article no. 014504

    SciTech Connect

    Kodama, T.; Enomoto, S.I.; Hatamachi, T.; Gokon, N.

    2008-02-15

    Solar thermochemical processes require the development of a high-temperature solar reactor operating at 1000-1500{sup o}C, such as solar gasification of coal and the thermal reduction of metal oxides as part of a two-step water splitting cycle. Here, we propose to apply 'an internally circulating fluidized bed' for a windowed solar chemical reactor in which reacting particles are directly illuminated. The prototype reactor was constructed in a laboratory scale and demonstrated on CO{sub 2} gasification of coal coke using solar-simulated, concentrated visible light from a sun simulator as the energy source. About 12% of the maximum chemical storage efficiency was obtained by the solar-simulated gasification of the coke.

  3. 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.

  4. The Lakeland McIntosh Unit 4 demonstration project utilizing Foster Wheeler`s pressurized circulating fluidized-bed combustion technology

    SciTech Connect

    McClung, J.D.; Provol, S.J.; Morehead, H.T.; Dodd, A.M.

    1997-12-31

    The City of Lakeland, Florida, Foster Wheeler and the Westinghouse Electric Corporation have embarked on the demonstration of a Clean Coal Technology at the City of Lakeland`s McIntosh Power Station in lakeland, Polk County, Florida. The project will demonstrate the Pressurized Circulating Fluidized Bed Combustion (PCFB) technology developed by Foster Wheeler and Westinghouse. The Lakeland McIntosh Unit 4 Project is a nominal 170 MW power plant designed to burn a range of low- to high-sulfur coals. The combined cycle plant employs a Westinghouse 251B12 gas turbine engine in conjunction with a steam turbine operating in a 2400/1000/1000 steam cycle. The plant will demonstrate both the PCFB and topped PCFB combustion technologies. This paper provides a process description of the Foster Wheeler PCFB and Topped PCFB technologies and their application to the Lakeland McIntosh Unit 4 Project.

  5. Engineering models for the gas-solid motion and interaction in the return loop of circulating fluidized beds. Topical report, January 1992--June 1992

    SciTech Connect

    Celik, I.; Zhang, G.Q.

    1992-08-01

    It is reported on development, testing and verification of engineering models for predicting the pressure drop, the solids flow rate, and the downcoming gas flow rate through an L-valve for a given aeration flow rate. The models are, in particular, applicable for studying the one-dimensional gas-solids motion through the return loop of a circulating fluidized bed. A literature review is presented in a comparative manner. One-dimensional transient equations governing the dense two-phase flows are derived. Those equations are then used to deduce relevant characteristic dimensionless parameters. Experimental data from literature have been analyzed and empirical correlations are suggested. A calculation procedure is proposed for predicting relevant gas and solid flow parameters. The model is based on integrated conservation equations for mass and momentum for both phases. Some experiments of our own have been performed and the data have been analyzed. The model is calibrated against experimental data.

  6. Voidage and pressure profile characteristics of sand-iron ore-coal-FCC single-particle systems in the riser of a pilot plant circulating fluidized bed

    SciTech Connect

    Das, M.; Meikap, B.C.; Saha, R.K.

    2008-06-15

    Hydrodynamic behaviors of single system of particles were investigated in a circulating fluidized bed (CFB) unit. Particles belonging to Geldart groups A and B like sand of various sizes (90, 300, 417, 522, 599, and 622 mu m), FCC catalyst (120 mu m), iron ore (166 and 140 {mu} m), and coal (335 and 168 {mu} m) were used to study the hydrodynamic characteristics. Superficial air velocity used in the present study ranged between 2.01 and 4.681 m/s and corresponding mass fluxes were 12.5-50 kg/(m{sup 2} s). A CFB needs the creation of some special hydrodynamic conditions, namely a certain combination of superficial gas velocity, solids circulation rate, particle diameter, density of particle, etc. which can give rise to a state wherein the solid particles are subjected to an upward velocity greater than the terminal or free fall velocity of the majority of the individual particles. The hydrodynamics of the bed was investigated in depth and theoretical analysis is presented to support the findings. Based on gas-solid momentum balance in the riser, a distinction between apparent and real voidage has been made. The effects of acceleration and friction on the real voidage have been estimated. Results indicated a 0.995 voidage for higher superficial gas velocity of 4.681. m/s.

  7. NO{sub x} formation and reduction during combustion of wet sewage sludge in the circulating fluidized bed -- Measurements and simulation

    SciTech Connect

    Philippek, C.; Knoebig, T.; Schoenfelder, H.; Werther, J.

    1997-12-31

    Mechanically dewatered municipal sewage sludge with a water content between 70 and 80 wt% was incinerated in a pilot-scale circulating fluidized bed (CFB). The combustion chamber had a total height of 15 m and a circular cross-section of 0.1 m diameter. In order to compensate for heat losses, the combustor was electrically heated from the outside. The combustion temperature of 850 C could thus be maintained along the whole length of the riser. Axial concentration profiles of the gaseous species O{sub 2}, CO{sub 2}, NO, N{sub 2}O, NH{sub 3} and organic carbon measured as CH{sub 4} were recorded for a variety of operating conditions. Since a major part of the investigation was devoted to the elucidation of the mechanisms of NO{sub x} formation and reduction in the case of combustion of wet sewage sludge, the combustor was also used for reaction kinetic studies whereby different gases, e.g., CO, NH{sub 3}, NO and N{sub 2}O were injected into the combustor which was during these experiments fluidized with nitrogen. The kinetic studies lead to a simplified kinetic scheme for NO{sub x} formation and reduction under conditions of sludge combustion. The combustor model divides the combustion chamber into four stages, i.e., a bottom zone, a splash-zone, an upper dilute zone and an exit zone. The bottom zone is modeled as a bubbling fluidized bed, whereas for the upper dilute zone a two-phase structure with an upflowing dilute suspension phase and a downflowing dense phase is assumed. This model is combined with a combustion model and the NO{sub x} formation and reduction model to form the CFB sludge combustor model. The calculations yield axial distributions of the different gaseous species which are shown to be fairly good agreement with the measurements. The model is able to explain the effects of different operating variables on the NO{sub x} emissions. IN particular, the model is able to explain why two-stage combustion, which in the case of coal combustion is

  8. Liquid-Solid Self-Lubricated Coatings

    NASA Astrophysics Data System (ADS)

    Armada, S.; Schmid, R.; Equey, S.; Fagoaga, I.; Espallargas, N.

    2013-02-01

    Self-lubricated coatings have been a major topic of interest in thermal spray in the last decades. Self-lubricated coatings obtained by thermal spray are exclusively based on solid lubricants (PTFE, h-BN, graphite, MoS2, etc.) embedded in the matrix. Production of thermal spray coatings containing liquid lubricants has not yet been achieved because of the complexity of keeping a liquid in a solid matrix during the spraying process. In the present article, the first liquid-solid self-lubricating thermal spray coatings are presented. The coatings are produced by inserting lubricant-filled capsules inside a polymeric matrix. The goal of the coating is to release lubricant to the system when needed. The first produced coatings consisted solely of capsules for confirming the feasibility of the process. For obtaining such a coating, the liquid-filled capsules were injected in the thermal spray flame without any other feedstock material. Once the concept and the idea were proven, a polymer was co-sprayed together with the capsules to obtain a coating containing the lubricant-filled capsules distributed in the solid polymeric matrix. The coatings and the self-lubricated properties have been investigated by means of optical microscopy, Scanning Electron Microscopy, and tribological tests.

  9. Development and Implementation of 3-D, High Speed Capacitance Tomography for Imaging Large-Scale, Cold-Flow Circulating Fluidized Bed

    SciTech Connect

    Marashdeh, Qussai

    2013-02-01

    A detailed understanding of multiphase flow behavior inside a Circulating Fluidized Bed (CFB) requires a 3-D technique capable of visualizing the flow field in real-time. Electrical Capacitance Volume Tomography (ECVT) is a newly developed technique that can provide such measurements. The attractiveness of the technique is in its low profile sensors, fast imaging speed and scalability to different section sizes, low operating cost, and safety. Moreover, the flexibility of ECVT sensors enable them to be designed around virtually any geometry, rendering them suitable to be used for measurement of solid flows in exit regions of the CFB. Tech4Imaging LLC has worked under contract with the U.S. Department of Energy's National Energy Technology Laboratory (DOE NETL) to develop an ECVT system for cold flow visualization and install it on a 12 inch ID circulating fluidized bed. The objective of this project was to help advance multi-phase flow science through implementation of an ECVT system on a cold flow model at DOE NETL. This project has responded to multi-phase community and industry needs of developing a tool that can be used to develop flow models, validate computational fluid dynamics simulations, provide detailed real-time feedback of process variables, and provide a comprehensive understating of multi-phase flow behavior. In this project, a complete ECVT system was successfully developed after considering different potential electronics and sensor designs. The system was tested at various flow conditions and with different materials, yielding real-time images of flow interaction in a gas-solid flow system. The system was installed on a 12 inch ID CFB of the US Department of Energy, Morgantown Labs. Technical and economic assessment of Scale-up and Commercialization of ECVT was also conducted. Experiments conducted with larger sensors in conditions similar to industrial settings are very promising. ECVT has also the potential to be developed for imaging multi

  10. 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.

  11. Liquid-Solid Nanofriction and Interfacial Wetting.

    PubMed

    An, Rong; Huang, Liangliang; Long, Yun; Kalanyan, Berc; Lu, Xiaohua; Gubbins, Keith E

    2016-01-26

    Using atomic force microscopy, the nanofriction coefficient was measured systematically for a series of liquids on planar graphite, silica and mica surfaces. This allows us to explore the quantitative interplay between nanofriction at liquid-solid interfaces and interfacial wetting. A corresponding states theory analysis shows that the nanofriction coefficient, μ = dF(F)/dF(N), where FF is the friction force and FN is the normal force, is a function of three dimensionless parameters that reflect the intermolecular forces involved and the structure of the solid substrate. Of these, we show that one parameter in particular, β = ρ(s)Δ(s)σ(ls)(2), where ρ(s) is the atomic density of the solid, Δ(s) is the spacing between layers of solid atoms, and σ(ls) is the molecular diameter that characterizes the liquid-substrate interaction, is very important in determining the friction coefficient. This parameter β, which we term the structure adhesion parameter, provides a measure of the intermolecular interaction between a liquid molecule and the substrate and also of the surface area of contact of the liquid molecule with the substrate. We find a linear dependence of μ on the structure adhesion parameter for the systems studied. We also find that increasing β leads to an increase in the vertical adhesion forces FA (the attractive force exerted by the solid surface on the liquid film). Our quantitative relationship between the nanofriction coefficient and the key parameter β which governs the vertical adhesive strength, opens up an opportunity for describing liquid flows on solid surfaces at the molecular level, with implications for the development of membrane and nanofluidic devices.

  12. On simulation of transfer processes in the freeboard region of a steam-generator furnace with a circulating fluidized bed

    SciTech Connect

    B.B. Rokhman

    2006-01-15

    A semiempirical, stationary, two-zone model of transfer processes in the freeboard region of a reactor with a circulating boiling layer has been constructed. The features of the aerodynamics, heat and mass transfer, and combustion of anthracite culm in the core and near-wall ring region of a flow in a KFS-0.2 pilot plant have been investigated in detail.

  13. Comprehensive report to Congress: Clean Coal Technology Program: Arvah B. Hopkins circulating fluidized-bed repowering project: A project proposed by: The City of Tallahassee

    SciTech Connect

    Not Available

    1990-10-01

    The project involves the repowering of a 250-megawatt electrical (MWe) natural gas- or oil-fired boiler with a coal-fired atmospheric circulating fluidized-bed (CFB) boiler to provide steam to an existing turbine generator. The boiler will be the largest of its type. After construction and shakedown, the City of Tallahassee (CoT) plant will be operated for 24 months with at least three different eastern coals. Final coal selection will be based on the Fuels Selection Study, which is part of Phase I-A of the project. Cost, financial, and technical data from the CoT CFB will be provided the utility industry for evaluation of a 250-MWe CFB as a commercially viable clean coal alternative. The objective of the Arvah B. Hopkins CFB Repowering Project is to demonstrate an efficient, economical, and environmentally superior method of generating electric power from coal. The work to be performed under the Cooperative Agreement includes the design, construction, and operation of the demonstration plant. 4 figs.

  14. The Midwest Power PCFB demonstration projects: AHLSTROM PYROFLOW{reg_sign} first and second generation pressurized circulating fluidized bed (PCFB) technology

    SciTech Connect

    Ambrose, S.; Green, C.L.; Dryden, R.; Provol, S.J.

    1993-04-01

    Midwest Power, Dairyland Power Cooperative, Pyropower Corporation (a subsidiary of Ahlstrom Pyropower Inc.), and Black & Veatch, have embarked on the demonstration of Clean Coal Technology (CCT) at Midwest Power`s Des Moines Energy Center (DMEC), in Pleasant Hill, Iowa. The DMEC-1 PCFB Demonstration Project was selected by the US Department of Energy for the demonstration of the First Generation Pressurized Circulating Fluidized Bed (PCFB) Technology. During Round 5 of the CCT Program, Midwest Power submitted a proposal for a second unit, to be known as DMEC-2. If selected by the DOE, the DMEC-2 unit will demonstrate Ahlstrom Pyropower`s Second Generation (Advanced) PCFB technology which will incorporate a topping combustor fired on coal derived gas generated in a PCFB carbonizer, to raise the firing temperature of the gas turbine and the total net plant efficiency. The First Generation PCFB technology has the capability to achieve 40--42% efficiency, the Second Generation technology can obtain an efficiency in the range of 44--47% net. This paper will provide a comparison of the commercial versions of the First and Second Generation PCFB systems, and the plans for demonstrating these systems for repowering and new plant installations during the late 1990`s and into the next century. A discussion of the DMEC-1 and DMEC-2 projects and their key technical features will be provided together with a projection of the future markets for these advanced clean coal technologies.

  15. The Midwest Power PCFB demonstration projects: AHLSTROM PYROFLOW[reg sign] first and second generation pressurized circulating fluidized bed (PCFB) technology

    SciTech Connect

    Ambrose, S.; Green, C.L.; Dryden, R.; Provol, S.J.

    1993-01-01

    Midwest Power, Dairyland Power Cooperative, Pyropower Corporation (a subsidiary of Ahlstrom Pyropower Inc.), and Black Veatch, have embarked on the demonstration of Clean Coal Technology (CCT) at Midwest Power's Des Moines Energy Center (DMEC), in Pleasant Hill, Iowa. The DMEC-1 PCFB Demonstration Project was selected by the US Department of Energy for the demonstration of the First Generation Pressurized Circulating Fluidized Bed (PCFB) Technology. During Round 5 of the CCT Program, Midwest Power submitted a proposal for a second unit, to be known as DMEC-2. If selected by the DOE, the DMEC-2 unit will demonstrate Ahlstrom Pyropower's Second Generation (Advanced) PCFB technology which will incorporate a topping combustor fired on coal derived gas generated in a PCFB carbonizer, to raise the firing temperature of the gas turbine and the total net plant efficiency. The First Generation PCFB technology has the capability to achieve 40--42% efficiency, the Second Generation technology can obtain an efficiency in the range of 44--47% net. This paper will provide a comparison of the commercial versions of the First and Second Generation PCFB systems, and the plans for demonstrating these systems for repowering and new plant installations during the late 1990's and into the next century. A discussion of the DMEC-1 and DMEC-2 projects and their key technical features will be provided together with a projection of the future markets for these advanced clean coal technologies.

  16. Effect of SiO2/Na2O mole ratio on the properties of foam geopolymers fabricated from circulating fluidized bed fly ash

    NASA Astrophysics Data System (ADS)

    Liu, Ze; Shao, Ning-ning; Huang, Tian-yong; Qin, Jun-feng; Wang, Dong-min; Yang, Yu

    2014-06-01

    Geopolymers are three-dimensional aluminosilicates formed in a short time at low temperature by geopolymerization. In this paper, alkali-activated foam geopolymers were fabricated from circulating fluidized bed fly ash (CFA), and the effect of SiO2/Na2O mole ratio (0.91-1.68) on their properties was studied. Geopolymerization products were characterized by mechanical testing, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The results show that SiO2/Na2O mole ratio plays an important role in the mechanical and morphological characteristics of geopolymers. Foam samples prepared in 28 d with a SiO2/Na2O mole ratio of 1.42 exhibit the greatest compressive strength of 2.52 MPa. Morphological analysis reveals that these foam geopolymers appear the relatively optimized pore structure and distribution, which are beneficial to the structure stability. Moreover, a combination of the Si/Al atomic ratio ranging between 1.47 and 1.94 with the Na/Al atomic ratio of about 1 produces the samples with high strength.

  17. 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.

  18. Circulating fluidized bed gasification of low rank coal: Influence of O2/C molar ratio on gasification performance and sulphur transformation

    NASA Astrophysics Data System (ADS)

    Zhang, Haixia; Zhang, Yukui; Zhu, Zhiping; Lu, Qinggang

    2016-08-01

    To promote the utilization efficiency of coal resources, and to assist with the control of sulphur during gasification and/or downstream processes, it is essential to gain basic knowledge of sulphur transformation associated with gasification performance. In this research we investigated the influence of O2/C molar ratio both on gasification performance and sulphur transformation of a low rank coal, and the sulphur transformation mechanism was also discussed. Experiments were performed in a circulating fluidized bed gasifier with O2/C molar ratio ranging from 0.39 to 0.78 mol/mol. The results showed that increasing the O2/C molar ratio from 0.39 to 0.78 mol/mol can increase carbon conversion from 57.65% to 91.92%, and increase sulphur release ratio from 29.66% to 63.11%. The increase of O2/C molar ratio favors the formation of H2S, and also favors the retained sulphur transforming to more stable forms. Due to the reducing conditions of coal gasification, H2S is the main form of the released sulphur, which could be formed by decomposition of pyrite and by secondary reactions. Bottom char shows lower sulphur content than fly ash, and mainly exist as sulphates. X-ray photoelectron spectroscopy (XPS) measurements also show that the intensity of pyrite declines and the intensity of sulphates increases for fly ash and bottom char, and the change is more obvious for bottom char. During CFB gasification process, bigger char particles circulate in the system and have longer residence time for further reaction, which favors the release of sulphur species and can enhance the retained sulphur transforming to more stable forms.

  19. 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... DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a) Identification. An air-fluidized bed is a device employing the circulation of filtered air through...

  20. 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... DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a) Identification. An air-fluidized bed is a device employing the circulation of filtered air through...

  1. 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.

  2. 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.

  3. 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

  4. Liquid-solid joining of bulk metallic glasses

    DOE PAGES

    Huang, Yongjiang; Xue, Peng; Guo, Shu; ...

    2016-07-29

    Here, we successfully welded two bulk metallic glass (BMG) materials, Zr51Ti5Ni10Cu25Al9 and Zr50.7Cu28Ni9Al12.3 (at. %), using a liquid-solid joining process. An atomic-scale metallurgical bonding between two BMGs can be achieved. The interface has a transition layer of ~50 μm thick. In conclusion, the liquid-solid joining of BMGs can shed more insights on overcoming their size limitation resulting from their limited glass-forming ability and then promoting their applications in structural components.

  5. Liquid-solid joining of bulk metallic glasses

    PubMed Central

    Huang, Yongjiang; Xue, Peng; Guo, Shu; Wu, Yang; Cheng, Xiang; Fan, Hongbo; Ning, Zhiliang; Cao, Fuyang; Xing, Dawei; Sun, Jianfei; Liaw, Peter K.

    2016-01-01

    Here, we successfully welded two bulk metallic glass (BMG) materials, Zr51Ti5Ni10Cu25Al9 and Zr50.7Cu28Ni9Al12.3 (at. %), using a liquid-solid joining process. An atomic-scale metallurgical bonding between two BMGs can be achieved. The interface has a transition layer of ~50 μm thick. The liquid-solid joining of BMGs can shed more insights on overcoming their size limitation resulting from their limited glass-forming ability and then promoting their applications in structural components. PMID:27471073

  6. Liquid-solid joining of bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Huang, Yongjiang; Xue, Peng; Guo, Shu; Wu, Yang; Cheng, Xiang; Fan, Hongbo; Ning, Zhiliang; Cao, Fuyang; Xing, Dawei; Sun, Jianfei; Liaw, Peter K.

    2016-07-01

    Here, we successfully welded two bulk metallic glass (BMG) materials, Zr51Ti5Ni10Cu25Al9 and Zr50.7Cu28Ni9Al12.3 (at. %), using a liquid-solid joining process. An atomic-scale metallurgical bonding between two BMGs can be achieved. The interface has a transition layer of ~50 μm thick. The liquid-solid joining of BMGs can shed more insights on overcoming their size limitation resulting from their limited glass-forming ability and then promoting their applications in structural components.

  7. Liquid-solid joining of bulk metallic glasses.

    PubMed

    Huang, Yongjiang; Xue, Peng; Guo, Shu; Wu, Yang; Cheng, Xiang; Fan, Hongbo; Ning, Zhiliang; Cao, Fuyang; Xing, Dawei; Sun, Jianfei; Liaw, Peter K

    2016-07-29

    Here, we successfully welded two bulk metallic glass (BMG) materials, Zr51Ti5Ni10Cu25Al9 and Zr50.7Cu28Ni9Al12.3 (at. %), using a liquid-solid joining process. An atomic-scale metallurgical bonding between two BMGs can be achieved. The interface has a transition layer of ~50 μm thick. The liquid-solid joining of BMGs can shed more insights on overcoming their size limitation resulting from their limited glass-forming ability and then promoting their applications in structural components.

  8. Finial Scientific/Technical Report: Application of a Circulating Fluidized Bed Process for the Chemical Looping Combustion of Solid Fuel

    SciTech Connect

    Dr. Wei-Ping Pan; Dr. John T. Riley

    2005-10-10

    Chemical Looping Combustion is a novel combustion technology for the inherent separation of the greenhouse gas, CO{sub 2}. In 1983, Richter and Knoche proposed reversible combustion, which utilized both the oxidation and reduction of metal. Metal associated with its oxidized form as an oxygen carrier was circulated between two reactors--oxidizer and reducer. In the reducer, the solid oxygen carrier reacts with the fuel to produce CO{sub 2}, H{sub 2}O and elemental metal only. Pure CO{sub 2} will be obtained in the exit gas stream from the reducer after H{sub 2}O is condensed. The pure CO{sub 2} is ready for subsequent sequestration. In the oxidizer, the elemental metal reacts with air to form metal oxide and separate oxygen from nitrogen. Only nitrogen and some unused oxygen are emitted from the oxidizer. The advantage of CLC compared to normal combustion is that CO{sub 2} is not diluted with nitrogen but obtained in a relatively pure form without any energy needed for separation. In addition to the energy-free purification of CO{sub 2}, the CLC process also provides two other benefits. First, NO{sub x} formation can be largely eliminated. Secondly, the thermal efficiency of a CLC system is very high. Presently, the CLC process has only been used with natural gas. An oxygen carrier based on an energy balance analysis and thermodynamics analysis was selected. Copper (Cu) seems to be the best choice for the CLC system for solid fuels. From this project, the mechanisms of CuO reduction by solid fuels may be as follows: (1) If pyrolysis products of solid fuels are available, reduction of CuO could start at about 400 C or less. (2) If pyrolysis products of solid fuels are unavailable and the reduction temperature is lower, reduction of CuO could occur at an onset temperature of about 500 C, char gasification reactivity in CO{sub 2} was lower at lower temperatures. (3) If pyrolysis products of solid fuels are unavailable and the reduction temperature is higher than 750 C

  9. Liquid-solid joining of bulk metallic glasses

    SciTech Connect

    Huang, Yongjiang; Xue, Peng; Guo, Shu; Wu, Yang; Cheng, Xiang; Fan, Hongbo; Ning, Zhiliang; Cao, Fuyang; Xing, Dawei; Sun, Jianfei; Liaw, Peter K.

    2016-07-29

    Here, we successfully welded two bulk metallic glass (BMG) materials, Zr51Ti5Ni10Cu25Al9 and Zr50.7Cu28Ni9Al12.3 (at. %), using a liquid-solid joining process. An atomic-scale metallurgical bonding between two BMGs can be achieved. The interface has a transition layer of ~50 μm thick. In conclusion, the liquid-solid joining of BMGs can shed more insights on overcoming their size limitation resulting from their limited glass-forming ability and then promoting their applications in structural components.

  10. Initiation of liquid-solid contact beneath an impacting drop

    NASA Astrophysics Data System (ADS)

    Rubinstein, Shmuel; Kolinski, John

    2015-11-01

    Before an impacting drop contacts the solid surface it must first drain the air beneath it. As a prelude to wetting, before any contact occurs, the impinging liquid confines the intervening air into a nanometers-thin film. Once liquid-solid contact initiates by the spontaneous formation of a liquid bridge, the fluid rapidly wicks through the thin film of air, permanently binding the drop to the surface. Here, we experimentally examine these initial stages in the formation of the liquid solid contact beneath the impacting drop. Fast TIR microscopy enables unprecedented spatial and temporal resolution of the wetting process beneath the impacting drop and permits 3-dimensional imaging of the real contact line as well as nanometer-resolution of the thin film of air separating the liquid from the solid.

  11. Silicon nanowire synthesis by a vapor-liquid-solid approach

    NASA Technical Reports Server (NTRS)

    Mao, Aaron; Ng, H. T.; Nguyen, Pho; McNeil, Melanie; Meyyappan, M.

    2005-01-01

    Synthesis of silicon nanowires is studied by using a vapor-liquid-solid growth technique. Silicon tetrachloride reduction with hydrogen in the gas phase is used with gold serving as catalyst to facilitate growth. Only a narrow set of conditions of SiCl4 concentration and temperature yield straight nanowires. High concentrations and temperatures generally result in particulates, catalyst coverage and deactivation, and coatinglike materials.

  12. Silicon nanowire synthesis by a vapor-liquid-solid approach

    NASA Technical Reports Server (NTRS)

    Mao, Aaron; Ng, H. T.; Nguyen, Pho; McNeil, Melanie; Meyyappan, M.

    2005-01-01

    Synthesis of silicon nanowires is studied by using a vapor-liquid-solid growth technique. Silicon tetrachloride reduction with hydrogen in the gas phase is used with gold serving as catalyst to facilitate growth. Only a narrow set of conditions of SiCl4 concentration and temperature yield straight nanowires. High concentrations and temperatures generally result in particulates, catalyst coverage and deactivation, and coatinglike materials.

  13. 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

  14. 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

    SciTech Connect

    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. The 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

  15. 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.

  16. Application of inverse fluidization in wastewater treatment: From laboratory to full-scale bioreactors

    SciTech Connect

    Karamanev, D.G.; Nikolov, L.N.

    1996-12-31

    The inverse fluidization is a new multiphase gas-liquid or gas-liquid-solid system. The first studies of two phase (liquid-solid) inverse fluidization were originally published independently by Shimodaira et al. [6], Nikolov et al. [5] and Fan et al. [2]. The main difference between the classic and inverse fluidization is that the solid particle density in the inverse fluidized bed is less than the density of the continuous fluid and therefore the bed is fluidized by a downflow of the fluid. Schematic illustration of both classic and inverse fluidized beds is shown in Figure 1. One of the most important recent applications of fluidized beds is in the field of bioreactor engineering. It is well known that almost all types of microorganisms spontaneously attach themselves to any inert solid surface in contact with the liquid growth media. The microorganisms use exopolysaccharide {open_quotes}bridges{close_quotes} to attach themselves to the solid support and to each other. This structure of microorganisms and exopolysaccharides is known as biofilm. The fluidized bed bioreactors are used primarily for processes in which the fluidized particles are used as an inert solid support. There is a problem when the biofilm microorganisms multiply and the biofilm thickness increase. This limits diffusion of oxygen and/or the organic substrate to the deeper layers of the biofilm. Starvation of the microorganisms at the base of the biofilm causes pieces of the biofilm to detach (Figure 2) and leads to ineffective bioreactor operation. The maximal biofilm thickness at which no diffusional limitation is observed (phase 3 in Figure 2), is usually around 100 {mu}m. Therefore, to operate the bioreactor efficiently, the biofilm thickness should be approximately 100 {mu}m. The use of inverse fluidization can solve this problem. 6 refs., 10 figs.

  17. 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.

  18. 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.

  19. 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.

  20. Flow-based solution-liquid-solid nanowire synthesis

    NASA Astrophysics Data System (ADS)

    Laocharoensuk, Rawiwan; Palaniappan, Kumaranand; Smith, Nickolaus A.; Dickerson, Robert M.; Werder, Donald J.; Baldwin, Jon K.; Hollingsworth, Jennifer A.

    2013-09-01

    Discovered almost two decades ago, the solution-liquid-solid (SLS) method for semiconductor nanowire synthesis has proven to be an important route to high-quality, single-crystalline anisotropic nanomaterials. In execution, the SLS technique is similar to colloidal quantum-dot synthesis in that it entails the injection of chemical precursors into a hot surfactant solution, but mechanistically it is considered the solution-phase analogue to vapour-liquid-solid (VLS) growth. Both SLS and VLS methods make use of molten metal nanoparticles to catalyse the nucleation and elongation of single-crystalline nanowires. Significantly, however, the methods differ in how chemical precursors are introduced to the metal catalysts. In SLS, precursors are added in a one-off fashion in a flask, whereas in VLS they are carried by a flow of gas through the reaction chamber, and by-products are removed similarly. The ability to dynamically control the introduction of reactants and removal of by-products in VLS synthesis has enabled a degree of synthetic control not possible with SLS growth. We show here that SLS synthesis can be transformed into a continuous technique using a microfluidic reactor. The resulting flow-based SLS (`flow-SLS') platform allows us to slow down the synthesis of nanowires and capture mechanistic details concerning their growth in the solution phase, as well as synthesize technologically relevant axially heterostructured semiconductor nanowires, while maintaining the propensity of SLS for accessing ultrasmall diameters below 10 nm.

  1. Combustion in fluidized beds

    SciTech Connect

    Dry, F.J.; La Nauze, R.D. )

    1990-07-01

    Circulating fluidized-bed (CFB) combustion systems have become popular since the late 1970s, and, given the current level of activity in the area,it is clear that this technology has a stable future in the boiler market. For standard coal combustion applications, competition is fierce with mature pulverized-fuel-based (PF) technology set to maintain a strong profile. CFB systems, however, can be more cost effective than PF systems when emission control is considered, and, as CFB technology matures, it is expected that an ever-increasing proportion of boiler installations will utilize the CFB concept. CFB systems have advantages in the combustion of low-grade fuels such as coal waste and biomass. In competition with conventional bubbling beds, the CFB boiler often demonstrates superior carbon burn-out efficiency. The key to this combustion technique is the hydrodynamic behavior of the fluidized bed. This article begins with a description of the fundamental fluid dynamic behavior of the CFB system. This is followed by an examination of the combustion process in such an environment and a discussion of the current status of the major CFB technologies.

  2. Vapor-liquid-solid growth of endotaxial semiconductor nanowires.

    PubMed

    Li, Shaozhou; Huang, Xiao; Liu, Qing; Cao, Xiehong; Huo, Fengwei; Zhang, Hua; Gan, Chee Lip

    2012-11-14

    Free-standing and in-plane lateral nanowires (NWs) grown by the vapor-liquid-solid (VLS) process have been widely reported. Herein, we demonstrate that the VLS method can be extended to the synthesis of horizontally aligned semiconductor NWs embedded in substrates. Endotaxial SiGe NWs were grown in silicon substrates by tuning the directional movement of the catalyst in the substrates. The location of the SiGe NWs can be controlled by the SiO(2) pattern on the silicon surface. By varying the growth conditions, the proportion of Ge in the obtained NWs can also be tuned. This approach opens up an opportunity for the spatial control of the NW growth in substrates and can potentially broaden the applications of NWs in new advanced fields.

  3. Liquid-liquid-solid transition in viscoelastic liquids

    PubMed Central

    Zubelewicz, Aleksander

    2013-01-01

    Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle. PMID:23429528

  4. MODELING AND SIMULATION OF SOLID FLUIDIZATION IN A RESIN COLUMN

    SciTech Connect

    Lee, S.

    2014-06-24

    The objective of the present work is to model the resin particles within the column during fluidization and sedimentation processes using computation fluid dynamics (CFD) approach. The calculated results will help interpret experimental results, and they will assist in providing guidance on specific details of testing design and establishing a basic understanding of particle’s hydraulic characteristics within the column. The model is benchmarked against the literature data and the test data (2003) conducted at Savannah River Site (SRS). The paper presents the benchmarking results and the modeling predictions of the SRS resin column using the improved literature correlations applicable for liquid-solid granular flow.

  5. MULTISTAGE FLUIDIZED BED REACTOR

    DOEpatents

    Jonke, A.A.; Graae, J.E.A.; Levitz, N.M.

    1959-11-01

    A multistage fluidized bed reactor is described in which each of a number of stages is arranged with respect to an associated baffle so that a fluidizing gas flows upward and a granular solid downward through the stages and baffles, whereas the granular solid stopsflowing downward when the flow of fluidizing gas is shut off.

  6. Spectral mapping of heat transfer mechanisms at liquid-solid interfaces

    NASA Astrophysics Data System (ADS)

    Sääskilahti, K.; Oksanen, J.; Tulkki, J.; Volz, S.

    2016-05-01

    Thermal transport through liquid-solid interfaces plays an important role in many chemical and biological processes, and better understanding of liquid-solid energy transfer is expected to enable improving the efficiency of thermally driven applications. We determine the spectral distribution of thermal current at liquid-solid interfaces from nonequilibrium molecular dynamics, delivering a detailed picture of the contributions of different vibrational modes to liquid-solid energy transfer. Our results show that surface modes located at the Brillouin zone edge and polarized along the liquid-solid surface normal play a crucial role in liquid-solid energy transfer. Strong liquid-solid adhesion allows also for the coupling of in-plane polarized modes in the solid with the liquid, enhancing the heat-transfer rate and enabling efficient energy transfer up to the cutoff frequency of the solid. Our results provide fundamental understanding of the energy-transfer mechanisms in liquid-solid systems and enable detailed investigations of energy transfer between, e.g., water and organic molecules.

  7. 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.

  8. 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.

  9. Liquid-solid contact during flow film boiling of subcooled freon-11

    SciTech Connect

    Chang, K.H.; Witte, L.C. )

    1990-05-01

    Liquid-solid contacts were measured for flow film boiling of subcooled Freon-11 over an electrically heated cylinder equipped with a surface microthermocouple probe. No systematic variation of the extent of liquid-solid contact with wall superheat, liquid subcooling, or velocity was detected. Only random small-scale contacts that contribute negligibly to overall heat transfer were detected when the surface was above the homogenous nucleation temperature of the Freon-11. When large-scale contacts were detected, they led to an unexpected intermediate transition from local film boiling to local transition boiling. An explanation is proposed for these unexpected transitions. A comparison of analytical results that used experimentally determined liquid-solid contact parameters to experimental heat fluxes did not show good agreement. It was concluded that the available model for heat transfer accounting for liquid-solid contact is not adequate for flow film boiling.

  10. Chiral induction and amplification in supramolecular systems at the liquid-solid interface.

    PubMed

    Xu, Hong; Ghijsens, Elke; George, Subi J; Wolffs, Martin; Tomović, Željko; Schenning, Albertus P H J; De Feyter, Steven

    2013-06-03

    Chiral induction and amplification in surface-confined supramolecular monolayers are investigated at the liquid-solid interface. Scanning tunneling microscopy (STM) proves that achiral molecules can self-assemble into globally chiral patterns through a variety of approaches, including induction by chiral solvents or by a novel chiral amplification method. Our study demonstrates the aptness of both approaches, which have already been applied to (supramolecular) polymers in solution, to create chiral supramolecular monolayers at the liquid-solid interface.

  11. Pressure Fluctuations as a Diagnostic Tool for Fluidized Beds

    SciTech Connect

    Ethan Bure; Joel R. Schroeder; Ramon De La Cruz; Robert C. Brown

    1998-05-01

    The purpose of this project was to investigate the origin of pressure fluctuations in fluidized bed systems. The study assessed the potential for using pressure fluctuations as an indicator of fluidized bed hydrodynamics in both laboratory scale cold-models and industrial scale boilers. Both bubbling fluidized beds and circulating fluidized beds were evaluated. Testing including both cold-flow models and laboratory and industrial-scale combustors operating at elevated temperatures. The study yielded several conclusions on the relationship of pressure fluctuations and hydrodynamic behavior in fluidized beds. The study revealed the importance of collecting sufficiently long data sets to capture low frequency (on the order of 1 Hz) pressure phenomena in fluidized beds. Past research has tended toward truncated data sets collected with high frequency response transducers, which miss much of the spectral structure of fluidized bed hydrodynamics. As a result, many previous studies have drawn conclusions concerning hydrodynamic similitude between model and prototype fluidized beds that is insupportable from the low resolution data presented.

  12. 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.

  13. Fluidized-bed boilers

    SciTech Connect

    Makansi, J.; Schwieger, B.

    1982-08-01

    This report reviews the current state of atmospheric fluidized-bed combustion. The fundamentals of fluidized-bed combustion and design considerations are first discussed. Tables provide details of manufacturers, worldwide, and of the boilers now installed. Eight plants in various countries and burning a variety of fuels, are described more fully.

  14. Three-phase gas-liquid-solid foaming bubble reactors and self-lubricated transport of bitumen froth

    NASA Astrophysics Data System (ADS)

    Mata, Clara E.

    Two distinct topics in multi-phase flow of interest of the oil industry are considered in this thesis. Studies of three-phase gas-liquid-solid foaming bubble reactors and self-lubricated transport of bitumen froth are reported. Applications of foams and foaming are found in many industrial processes such as flotation of minerals, enhanced oil recovery, drilling in oil reservoirs, and refining processes. However the physics of foaming and defoaming are not fully understood. Foams trap gas and are not desirable in some processes such as oil refining. Previously, it has been found that foaming may be strongly suppressed in a cold slit bubble reactor by fluidizing hydrophilic particles in the bubbly mixture below the foam. In this work, we fluidized hydrophobic and hydrophilic versions of two different sands in a cold slit foaming bubble reactor. We found that the hydrophobic sands suppress the foam substantially better than their hydrophilic counterparts. To study the capacity of foams to carry particles, we built a new slit foaming bubble reactor, which can be continuously fed with solid particles. Global gas, liquid, and solid holdups were measured for given gas and liquid velocities and solid flow rates. This research provides the fundamental ground work for the identification of flow types in a slit three-phase foaming bubble reactor with continuous injection of particles. Bitumen froth is produced from the oil sands of Athabasca, Canada. When transported in a pipeline, water present in the froth is released in regions of high shear (at the pipe wall). This results in a lubricating layer of water that allows bitumen froth pumping at greatly reduced pressures and hence the potential for savings in pumping energy consumption. Experimental results establishing the features of this self lubrication phenomenon are presented. The pressure gradient of lubricated flows closely follow the empirical law of Blasius for turbulent pipe flow with a constant of proportionality

  15. 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.

  16. 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.

  17. Effect of arm exchange on the liquid-solid transition of dense suspensions of star polymers.

    PubMed

    Puaud, Fanny; Nicolai, Taco; Benyahia, Lazhar; Nicol, Erwan

    2013-10-10

    Star polymers with dynamic arm exchange are formed in water by self-assembly of amphiphilic diblock copolymers based on poly(ethylene oxide) end capped with a small hydrophobic block. The arm exchange was arrested in situ by photo-cross-linking of the core. The effect of dynamic arm exchange on the osmotic compressibility and viscosity was investigated systematically as a function of the concentration and temperature. The discontinuous liquid-solid transition reported for dense polymeric micelle suspensions was found to be preserved after dynamic arm exchange was arrested in situ. The effect of cross-linking and aggregation number on the liquid-solid transition was investigated.

  18. Fluidized bed heat treating system

    DOEpatents

    Ripley, Edward B; Pfennigwerth, Glenn L

    2014-05-06

    Systems for heat treating materials are presented. The systems typically involve a fluidized bed that contains granulated heat treating material. In some embodiments a fluid, such as an inert gas, is flowed through the granulated heat treating medium, which homogenizes the temperature of the heat treating medium. In some embodiments the fluid may be heated in a heating vessel and flowed into the process chamber where the fluid is then flowed through the granulated heat treating medium. In some embodiments the heat treating material may be liquid or granulated heat treating material and the heat treating material may be circulated through a heating vessel into a process chamber where the heat treating material contacts the material to be heat treated. Microwave energy may be used to provide the source of heat for heat treating systems.

  19. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    SciTech Connect

    Not Available

    1992-02-01

    The report summarizes unit operating experience and test program progress for 1989 on Colorado-Ute Electric Association's Nucla CFB Demonstration Program. During this period, the objectives of the Nucla Station operating group were to correct problems with refractory durability, resolve primary air fan capacity limitations, complete the high ash and high sulfur coal tests, switch to Salt Creek coal as the operating fuel, and make the unit available for testing without capacity restrictions. Each of these objectives was addressed and accomplished, to varying degrees, except for the completion of the high sulfur coal acceptance tests. (VC)

  20. Carbon nitride nanocrystals having cubic structure using pulsed laser induced liquid-solid interfacial reaction

    NASA Astrophysics Data System (ADS)

    Yang, G. W.; Wang, J. B.

    Carbon nitride nanocrystals were prepared using a pulsed laser induced liquid-solid interfacial reaction and transmission electron microscopy, while high resolution electron microscopy characterized their morphology and structure. It is important that the cubic-C3N4 phase was observed. The formation mechanism of the carbon nitride nanocrystals is also discussed.

  1. Naturally occurring vapor-liquid-solid (VLS) Whisker growth of germanium sulfide

    USGS Publications Warehouse

    Finkelman, R.B.; Larson, R.R.; Dwornik, E.J.

    1974-01-01

    The first naturally occurring terrestrial example of vapor-liquid-solid (VLS) growth has been observed in condensates from gases released by burning coal in culm banks. Scanning electron microscopy, X-ray diffraction, and energy dispersive analysis indicate that the crystals consist of elongated rods (??? 100 ??m) of germanium sulfide capped by bulbs depleted in germanium. ?? 1974.

  2. 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".

  3. Fluidized-bed boilers achieve commercial status worldwide

    SciTech Connect

    Schwieger, B.

    1985-02-01

    The author reviews the current status of commercial fluidized-bed boilers worldwide. Particular attention is given to circulating fluidised-bed systems. A number of detailed tables are presented providing details of manufacturers of afb boilers, and information on 88 installed boilers, their fuels, combustion systems and operational data. Less detailed information is given of a further 140 installations.

  4. Fluidized-bed combustion

    SciTech Connect

    Botros, P E

    1990-04-01

    This report describes the activities of the Morgantown Energy Technology Center's research and development program in fluidized-bed combustion from October 1, 1987, to September 30, 1989. The Department of Energy program involves atmospheric and pressurized systems. Demonstrations of industrial-scale atmospheric systems are being completed, and smaller boilers are being explored. These systems include vortex, multi-solid, spouted, dual-sided, air-cooled, pulsed, and waste-fired fluidized-beds. Combustion of low-rank coal, components, and erosion are being studied. In pressurized combustion, first-generation, combined-cycle power plants are being tested, and second-generation, advanced-cycle systems are being designed and cost evaluated. Research in coal devolatilization, metal wastage, tube corrosion, and fluidization also supports this area. 52 refs., 24 figs., 3 tabs.

  5. 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.

  6. 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.

  7. 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.

  8. Fluidized crater ejecta

    NASA Image and Video Library

    2002-12-13

    The ejecta blanket of the crater in this image from NASA Mars Odyssey spacecraft does not resemble the blocky, discontinuous ejecta associated with most fresh craters on Mars. Rather, the continuous lobes of material seen around this crater are evidence that the crater ejecta were fluidized upon impact of the meteor that formed this crater. Impact ejecta become fluidized when a meteor strikes a surface that has a considerable volatile content. The volatiles mixed with the ejecta form a flow of material that moves outward from the crater and produces the morphology seen in this THEMIS visible image. http://photojournal.jpl.nasa.gov/catalog/PIA04025

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Pulsed atmospheric fluidized bed combustion

    SciTech Connect

    Not Available

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  16. Research on Fluidization.

    ERIC Educational Resources Information Center

    Bailie, Richard C.; And Others

    1985-01-01

    West Virginia University was designated by the National Science Foundation (NSF) as the NSF University/Industry Fluidization and Fluid Particle Cooperative Research Center. Background information about the center, its research program (focusing on fundamental problems of reacting systems at elevated temperatures), and future prospects are…

  17. 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.

  18. 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.

  19. 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.

  20. Technical advances and new opportunities for fluidized bed combustion

    SciTech Connect

    Alliston, M.G.; Kokko, A.; Martin, B.G.; Olofsson, J.

    1997-12-31

    This paper outlines opportunities for new circulating fluidized bed (CFB) boilers, technical considerations in selecting a fluidized bed boiler, and CFB boiler configuration types and sizes. New opportunities for CFBs include fuel opportunities from coke, mine mouth coals, and waste products, and boiler application opportunities in industrial cogeneration, repowering, and developing nations. Technical considerations discussed for boiler selection are fuel flexibility and environmental aspects. Three boiler configurations are briefly described: (1) water-cooled cyclone with water-cooled loopseal, (2) integral cylindrical cyclone and loopseal, and (3) Cylindrical multi-inlet cyclone. CFB scale-up is also briefly discussed. 3 refs., 3 figs.

  1. First-principles quantum-mechanical investigations of biomass conversion at the liquid-solid interfaces

    NASA Astrophysics Data System (ADS)

    Dang, Hongli; Xue, Wenhua; Liu, Yingdi; Jentoft, Friederike; Resasco, Daniel; Wang, Sanwu

    2014-03-01

    We report first-principles density-functional calculations and ab initio molecular dynamics (MD) simulations for the reactions involving furfural, which is an important intermediate in biomass conversion, at the catalytic liquid-solid interfaces. The different dynamic processes of furfural at the water-Cu(111) and water-Pd(111) interfaces suggest different catalytic reaction mechanisms for the conversion of furfural. Simulations for the dynamic processes with and without hydrogen demonstrate the importance of the liquid-solid interface as well as the presence of hydrogen in possible catalytic reactions including hydrogenation and decarbonylation of furfural. Supported by DOE (DE-SC0004600). This research used the supercomputer resources of the XSEDE, the NERSC Center, and the Tandy Supercomputing Center.

  2. An innovative vibration fluidized bed ash cooler

    SciTech Connect

    Duan, Y.; Zhang, M.; Liu, A.; Yao, Z.; Tang, H.; Liu, Q.

    1999-07-01

    With the ever-increasing versatility, scaling up and commercialization of coal-fired fluidized bed boiler technologies, it has become more and more important to improve the technique of draining bed ash from bubbling or circulating fluidized bed boilers. Choosing an ash cooler is a good way but highly stable and reliable system is hard to find for a massive ash flow rate having a broad particle size distributions. An innovative technique known as Vibration Fluidized Bed Ash Cooler (VFBAC) is proposed in this paper. It can drain bottom ash at a high temperature from FB or CFB boilers continuously and controllably. In this device, air used for cooling can be used as combustion-aided air or coal spreading air. The hot ash is cooled by the air to a temperature which it can be transported easily and safely by conventional technology. Meanwhile, an industrial apparatus utilizing the new technology was manufactured and used in a 35 t/h bubbling FB boiler. For the purpose of detecting residence time distribution of wide-sieved bed materials in this ash cooler systematically, advantage was taken of a new approach for physical quality discrimination. Investigations into the hydrodynamic characteristics of the gas-solid two-phase flows and theoretical analyses on hot operational performance were carried out. The results show that heat recovery efficiency of the ash cooler reaches 85% greater when operating at a ratio of air to ash of 1.5{approximately}2.5 Nm{sup 3}/kg.

  3. Break-down of a planar liquid-solid interface during directional solidification - Influence of convection

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Chopra, M. A.

    1992-01-01

    The influence of convection on the development of morphological instability at the liquid-solid interface during directional solidification in a positive thermal gradient has been examined in Pb-10 wt pct Sn and succinonitrile-1.9 wt pct acetone. The onset of interfacial breakdown occurs at higher growth speeds in the presence of convection. The linear stability analysis due to Favier and Rouzaud which uses the 'deformable' mass flow boundary layer concept shows a good agreement with the experimentally observed behavior.

  4. Microspheres for the growth of silicon nanowires via vapor-liquid-solid mechanism

    DOE PAGES

    Gomez-Martinez, Arancha; Marquez, Francisco; Elizalde, Eduardo; ...

    2014-01-01

    Silicon nanowires have been synthesized by a simple process using a suitable support containing silica and carbon microspheres. Nanowires were grown by thermal chemical vapor deposition via a vapor-liquid-solid mechanism with only the substrate as silicon source. The curved surface of the microsized spheres allows arranging the gold catalyst as nanoparticles with appropriate dimensions to catalyze the growth of nanowires. Here, the resulting material is composed of the microspheres with the silicon nanowires attached on their surface.

  5. Gold-catalyzed vapor-liquid-solid germanium-nanowire nucleation on porous silicon.

    PubMed

    Koto, Makoto; Marshall, Ann F; Goldthorpe, Irene A; McIntyre, Paul C

    2010-05-07

    Nanoporous Si(111) substrates are used to study the effects of Au catalyst coarsening on the nucleation of vapor-liquid-solid-synthesized epitaxial Ge nanowires (NWs) at temperatures less than 400 degrees C. Porous Si substrates, with greater effective interparticle separations for Au surface diffusion than nonporous Si, inhibit catalyst coarsening and agglomeration prior to NW nucleation. This greatly reduces the variation in wire diameter and length and increases the yield compared to nucleation on identically prepared nonporous Si substrates.

  6. Fluidization of nanopowders: a review.

    PubMed

    van Ommen, J Ruud; Valverde, Jose Manuel; Pfeffer, Robert

    2012-03-01

    Nanoparticles (NPs) are applied in a wide range of processes, and their use continues to increase. Fluidization is one of the best techniques available to disperse and process NPs. NPs cannot be fluidized individually; they fluidize as very porous agglomerates. The objective of this article is to review the developments in nanopowder fluidization. Often, it is needed to apply an assistance method, such as vibration or microjets, to obtain proper fluidization. These methods can greatly improve the fluidization characteristics, strongly increase the bed expansion, and lead to a better mixing of the bed material. Several approaches have been applied to model the behavior of fluidized nanopowders. The average size of fluidized NP agglomerates can be estimated using a force balance or by a modified Richardson and Zaki equation. Some first attempts have been made to apply computational fluid dynamics. Fluidization can also be used to provide individual NPs with a thin coating of another material and to mix two different species of nanopowder. The application of nanopowder fluidization in practice is still limited, but a wide range of potential applications is foreseen. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11051-012-0737-4) contains supplementary material, which is available to authorized users.

  7. Manifestations of non-planar adsorption geometries of lead pyrenocyanine at the liquid-solid interface.

    PubMed

    Mali, Kunal S; Zöphel, Lukas; Ivasenko, Oleksandr; Müllen, Klaus; De Feyter, Steven

    2013-10-01

    In this work, we provide evidence for multiple non-planar adsorption geometries of a novel pyrenocyanine derivative at the liquid-solid interface under ambient conditions. When adsorbed at the organic liquid-solid interface, lead pyrenocyanine forms well-ordered monolayers that exhibit peculiar non-periodic contrast variation. The different contrast of the adsorbed molecules is attributed to dissimilar adsorption geometries which arise from the non-planar conformation of the molecules. The non-planarity of the molecular backbone in turn arises due to a combination of the angularly extended pyrene subunits and the presence of the large lead ion, which is too big to fit inside the central cavity and thus is located out of the aromatic plane. The two possible locations of the lead atom, namely below and above the aromatic plane, could be identified as depression and protrusion in the central cavity, respectively. The manifestation of such multiple adsorption geometries on the structure of the resultant monolayer is discussed in detail. The packing density of these 2D arrays of molecules could be tuned by heating of the sample wherein the molecular packing changes from a low-density, pseudo six-fold symmetric to a high-density, two-fold symmetric arrangement. Finally, a well-ordered two-component system could be constructed by incorporating C60 molecules in the adlayer of lead pyrenocyanine at the liquid-solid interface.

  8. Influence of process parameters to composite interface organization and performance of liquid/solid bimetal

    NASA Astrophysics Data System (ADS)

    Rong, S. F.; Zhu, Y. C.; Wu, Y. H.; Yang, P. H.; Duan, X. L.; Zhou, H. T.

    2015-12-01

    The liquid-solid composite technique was used to prepare the high carbon high chromium steel (HCHCS) and low alloy steel (LCS) bimetal composite materials by means of insert casting method. The influence of some process parameters such as liquid-solid ratio, preheat temperature, pouring temperature on the interface microstructure and mechanical properties were studied. Interface microstructure and element distribution were analyzed. The results show that the interface microstructure becomes better, and bonding area becomes thicker with the increase of the volume of liquid to solid ratio, preheating temperature and pouring temperature. When the liquid-solid ratio is 8:1, the preheating temperature is 300 °C and the pouring temperature is 1565 °C, a good metallurgical bonding area without any hole can be obtained with the interface combination of diffusion and fusion. The composite interface structure was composed of a core material diffusion layer, a cooling solidification layer, a direction growth layer and some cell particles. The elements of C, Cr and Mn diffuse from the HCHCS side to the alloy steel side. The microhardness increased in the gradient from the LCS side to the HCHCS. The microhardness of the interface is significantly higher than that of LCS.

  9. Fluidization, combustion and emission behavior of biomass in fluidized bed combustion units

    SciTech Connect

    Kaeferstein, P.; Tepper, H.; Gohla, M.; Reimer, H.

    1997-12-31

    Gaseous components were measured over the height and the cross section inside a circulating fluidized bed riser with a thermal power of 60 kW. The combustion behavior of lignite (German brown coal), hard coal, biomass (China reed), and sewage sludge was investigated. The burn-out behavior was investigated by in-situ and real time measurement of the oxygen consumption using solid electrolyte sensor probes within a bubbling fluidized bed combustor with 15 kW thermal power. Non-uniform oxygen concentration profiles were found over the small riser cross-section which differed for the various fuels. The feed location and the fuel distribution also influences the horizontal oxygen profile. The reasons for the non-uniformity of the horizontal oxygen concentration profile are the combustion of volatile matter and the recirculation of char near the walls. A simulation model was developed to calculate the hydrodynamics and the oxygen consumption for the difference fuels inside the CFBC riser.

  10. Torrefaction of sawdust in a fluidized bed reactor.

    PubMed

    Li, Hui; Liu, Xinhua; Legros, Robert; Bi, Xiaotao T; Lim, C J; Sokhansanj, Shahab

    2012-01-01

    In the present work, stable fluidization of sawdust was achieved in a bench fluidized bed with an inclined orifice distributor without inert bed materials. A solids circulation pattern was established in the bed without the presence of slugging and channeling. The effects of treatment severity and weight loss on the solid product properties were identified. The decomposition of hemicelluloses was found to be responsible for the significant changes of chemical, physical and mechanical properties of the torrefied sawdust, including energy content, particle size distribution and moisture absorption capacity. The hydrophobicity of the torrefied sawdust was improved over the raw sawdust with a reduction of around 40 wt.% in saturated water uptake rate, and enhanced with increasing the treatment severity due to the decomposition of hemicelluloses which are rich in hydroxyl groups. The results in this study provided the basis for torrefaction in fluidized bed reactors.

  11. 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.

  12. Fluidized bed desulfurization

    NASA Technical Reports Server (NTRS)

    Ravindram, M.; Kallvinskas, J. J. (Inventor)

    1985-01-01

    High sulfur content carbonaceous material, such as coal is desulfurized by continuous fluidized suspension in a reactor with chlorine gas, inert dechlorinating gas and hydrogen gas. A source of chlorine gas, a source of inert gas and a source of hydrogen gas are connected to the bottom inlet through a manifold and a heater. A flow controler operates servos in a manner to continuously and sequentially suspend coal in the three gases. The sulfur content is reduced at least 50% by the treatment.

  13. Fluidized-bed boilers

    SciTech Connect

    Makansi, J.; Schwieger, B.

    1982-08-01

    Discusses atmospheric fluidized-bed (AFB) boilers with regard to designs available, manufacturers involved, and operating experience. Proven fuel flexibility and satisfactory SO/sub 2/ control without scrubbers make AFB boilers a viable option for industrial steam generation worldwide. Technical concepts on which AFB application is based are a departure from the more familiar methods of burning solid fuels. Behind US thrust for AFB development is the need to burn coal within pollution regulations.

  14. Mathematical modeling of a fluidized bed straw gasifier. Part 2: Model sensitivity

    SciTech Connect

    Erguedenler, A.; Ghaly, A.E.; Hamdullahpur, F.; Al-Taweel, A.M.

    1997-12-01

    The sensitivity of the kinetic-free homogeneous equilibrium model, developed for fluidized bed gasification of cereal straw, was tested under a wide range of parameters, including equivalence ratio, bed height, fluidization velocity, solid circulation coefficient, nitrogen-oxygen ratio, and fuel distribution function. The results showed that the bed temperature was sensitive to changes in all of these parameters. The composition and the higher heating value of the produced gas were only affected by the equivalence ratio and the nitrogen-oxygen ratio. The normalized gas production was mainly affected by the equivalence ratio, fluidization velocity, and nitrogen-oxygen ratio.

  15. Engineering adhesion to thermoresponsive substrates: effect of polymer composition on liquid-liquid-solid wetting.

    PubMed

    Gambinossi, Filippo; Sefcik, Lauren S; Wischerhoff, Erik; Laschewsky, Andre; Ferri, James K

    2015-02-04

    Adhesion control in liquid-liquid-solid systems represents a challenge for applications ranging from self-cleaning to biocompatibility of engineered materials. By using responsive polymer chemistry and molecular self-assembly, adhesion at solid/liquid interfaces can be achieved and modulated by external stimuli. Here, we utilize thermosensitive polymeric materials based on random copolymers of di(ethylene glycol) methyl ether methacrylate (x = MEO2MA) and oligo(ethylene glycol) methyl ether methacrylate (y = OEGMA), that is, P(MEO2MAx-co-OEGMAy), to investigate the role of hydrophobicity on the phenomenon of adhesion. The copolymer ratio (x/y) dictates macromolecular changes enabling control of the hydrophilic-to-lipophilic balance (HBL) of the polymer brushes through external triggers such as ionic strength and temperature. We discuss the HBL of the thermobrushes in terms of the surface energy of the substrate by measuring the contact angle at water-decane-P(MEO2MAx-co-OEGMAy) brush contact line as a function of polymer composition and temperature. Solid supported polyelectrolyte layers grafted with P(MEO2MAx-co-OEGMAy) display a transition in the wettability that is related to the lower critical solution temperature of the polymer brushes. Using experimental observation of the hydrophilic to hydrophobic transition by the contact angle, we extract the underlying energetics associated with liquid-liquid-solid adhesion as a function of the copolymer ratio. The change in cellular attachment on P(MEO2MAx-co-OEGMAy) substrates of variable (x/y) composition demonstrates the subtle role of compositional tuning on the ability to control liquid-liquid-solid adhesion in biological applications.

  16. Localized single molecule isotherms of DNA molecules at confined liquid-solid interfaces.

    PubMed

    Liang, Heng; Cheng, Xiaoliang; Ma, Yinfa

    2009-03-15

    The study of dynamics and thermodynamics of single biological molecules at confined liquid-solid interfaces is crucially important, especially in the case of low-copy number molecules in a single cell. Using a high-throughput single molecule imaging system and Lagrangian coordinates of single molecule images, we discovered that the local equilibrium isotherms of single lambdaDNA molecules at a confined liquid-solid interface varied from a stair type for the regions of single or double molecular DNA to a mild "S" type for the regions of triple molecular DNA spots, which does not agree with the conventional equilibrium isotherms in the literature. Single molecule images in time sequence for different lambdaDNA concentrations were statistically analyzed by measuring preferential partitioning from shearing effects, which were used to measure the local velocity of DNA molecules by directly observing the migration of DNA fluorescence spots for the 12 continuous images. The local linear velocity of hydrodynamic flow was calculated by the Hagen-Poiseuille equation in different microregions with a local Lagrangian approach. The local single molecule isotherms for the tracked molecules in the regions of single, double, or triple molecular DNA layers within the laminar flows were obtained according to the average local velocities of both the stochastic molecule events and the corresponding local Poiseuille flows. A millisecond and microvolume approach to directly determine local single molecule isotherms at confined liquid-solid interfaces was established, and the microspace scale effects on the types of isotherms were discovered. This study may have significant impact on preparations of low-copy number proteins in a single cell, membrane separations, and other bioseparation studies.

  17. Solution-Liquid-Solid Synthesis of Hexagonal Nickel Selenide Nanowire Arrays with a Nonmetal Catalyst.

    PubMed

    Xu, Kun; Ding, Hui; Jia, Kaicheng; Lu, Xiuli; Chen, Pengzuo; Zhou, Tianpei; Cheng, Han; Liu, Si; Wu, Changzheng; Xie, Yi

    2016-01-26

    Inorganic nanowire arrays hold great promise for next-generation energy storage and conversion devices. Understanding the growth mechanism of nanowire arrays is of considerable interest for expanding the range of applications. Herein, we report the solution-liquid-solid (SLS) synthesis of hexagonal nickel selenide nanowires by using a nonmetal molecular crystal (selenium) as catalyst, which successfully brings SLS into the realm of conventional low-temperature solution synthesis. As a proof-of-concept application, the NiSe nanowire array was used as a catalyst for electrochemical water oxidation. This approach offers a new possibility to design arrays of inorganic nanowires.

  18. Green-Kubo relation for friction at liquid-solid interfaces

    NASA Astrophysics Data System (ADS)

    Huang, Kai; Szlufarska, Izabela

    2014-03-01

    We have developed a Green-Kubo relation that enables accurate calculations of friction at solid-liquid interfaces directly from equilibrium molecular dynamics (MD) simulations and that provides a pathway to bypass the time-scale limitations of typical nonequilibrium MD simulations. The theory has been validated for a number of different interfaces and it is demonstrated that the liquid-solid slip is an intrinsic property of an interface. Because of the high numerical efficiency of our method, it can be used in the design of interfaces for applications in aqueous environments, such as nano- and microfluidics.

  19. Corner wetting during the vapor-liquid-solid growth of faceted nanowires

    NASA Astrophysics Data System (ADS)

    Spencer, Brian; Davis, Stephen

    2016-11-01

    We consider the corner wetting of liquid drops in the context of vapor-liquid-solid growth of nanowires. Specifically, we construct numerical solutions for the equilibrium shape of a liquid drop on top of a faceted nanowire by solving the Laplace-Young equation with a free boundary determined by mixed boundary conditions. A key result for nanowire growth is that for a range of contact angles there is no equilibrium drop shape that completely wets the corner of the faceted nanowire. Based on our numerical solutions we determine the scaling behavior for the singular surface behavior near corners of the nanowire in terms of the Young contact angle and drop volume.

  20. Phase diagram of nanoscale alloy particles used for vapor-liquid-solid growth of semiconductor nanowires.

    PubMed

    Sutter, Eli; Sutter, Peter

    2008-02-01

    We use transmission electron microscopy observations to establish the parts of the phase diagram of nanometer sized Au-Ge alloy drops at the tips of Ge nanowires (NWs) that determine their temperature-dependent equilibrium composition and, hence, their exchange of semiconductor material with the NWs. We find that the phase diagram of the nanoscale drop deviates significantly from that of the bulk alloy, which explains discrepancies between actual growth results and predictions on the basis of the bulk-phase equilibria. Our findings provide the basis for tailoring vapor-liquid-solid growth to achieve complex one-dimensional materials geometries.

  1. Microspheres for the growth of silicon nanowires via vapor-liquid-solid mechanism

    SciTech Connect

    Gomez-Martinez, Arancha; Marquez, Francisco; Elizalde, Eduardo; Morant, Carmen

    2014-01-01

    Silicon nanowires have been synthesized by a simple process using a suitable support containing silica and carbon microspheres. Nanowires were grown by thermal chemical vapor deposition via a vapor-liquid-solid mechanism with only the substrate as silicon source. The curved surface of the microsized spheres allows arranging the gold catalyst as nanoparticles with appropriate dimensions to catalyze the growth of nanowires. Here, the resulting material is composed of the microspheres with the silicon nanowires attached on their surface.

  2. Synthesis of gold-silica composite nanowires through solid-liquid-solid phase growth.

    PubMed

    Paulose, Maggie; Varghese, Oomman K; Grimes, Craig A

    2003-08-01

    Nanoscale wires of silicon oxide, and silicon oxide with embedded gold-silicide nanospheres, are synthesized by heating of a gold-coated silicon wafer at temperatures of 1000 degrees C or above, with the resulting wires having diameters ranging from 30 to 150 nm and lengths of approximately 1 mm. This simple fabrication process should make possible economical bulk production of nanowires. Studies indicate that the growth of these gold-silica composite nanowires occurs directly on the silicon wafer by a solid-liquid-solid mechanism.

  3. Relaxation of surface tension in the liquid-solid interfaces of Lennard-Jones liquids.

    PubMed

    Lukyanov, Alex V; Likhtman, Alexei E

    2013-11-19

    We have established the surface tension relaxation time in the liquid-solid interfaces of Lennard-Jones (LJ) liquids by means of direct measurements in molecular dynamics (MD) simulations. The main result is that the relaxation time is found to be almost independent of the molecular structures and viscosity of the liquids (at 70-fold change) used in our study and lies in such a range that in slow hydrodynamic motion the interfaces are expected to be at equilibrium. The implications of our results for the modeling of dynamic wetting processes and interpretation of dynamic contact angle data are discussed.

  4. 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.

  5. Fluidized-bed sorbents

    SciTech Connect

    Gangwal, S.K.; Gupta, R.P.

    1994-10-01

    The objectives of this project are to identify and demonstrate methods for enhancing long-term chemical reactivity and attrition resistance of zinc oxide-based mixed metal-oxide sorbents for desulfurization of hot coal-derived gases in a high-temperature, high-pressure (HTHP) fluidized-bed reactor. In this program, regenerable ZnO-based mixed metal-oxide sorbents are being developed and tested. These include zinc ferrite, zinc titanate, and Z-SORB sorbents. The Z-SORB sorbent is a proprietary sorbent developed by Phillips Petroleum Company (PPCo).

  6. The competition between the liquid-liquid dewetting and the liquid-solid dewetting.

    PubMed

    Xu, Lin; Shi, Tongfei; An, Lijia

    2009-05-14

    We investigate the dewetting behavior of the bilayer of air/PS/PMMA/silanized Si wafer and find the two competing dewetting pathways in the dewetting process. The upper layer dewets on the lower layer (dewetting pathway 1, the liquid-liquid dewetting) and the two layers rupture on the solid substrate (dewetting pathway 2, the liquid-solid dewetting). To the two competing dewetting pathways, the process of forming holes and the process of hole growth, influence their competing relation. In the process of forming holes, the time of forming holes is a main factor that influences their competing relation. During the process of hole growth, the dewetting velocity is a main factor that influences their competing relation. The liquid-liquid interfacial tension, the film thickness of the polymer, and the viscosity of the polymer are important factors that influence the time of forming holes and the dewetting velocity. When the liquid-liquid dewetting pathway and the liquid-solid dewetting pathway compete in the dewetting process, the competing relation can be controlled by changing the molecular weight of the polymer, the film thickness, and the annealing temperature. In addition, it is also found that the rim growth on the solid substrate is by a rolling mechanism in the process of hole growth.

  7. Pyridinium ionic liquid-based liquid-solid extraction of inorganic and organic iodine from Laminaria.

    PubMed

    Peng, Li-Qing; Yu, Wen-Yan; Xu, Jing-Jing; Cao, Jun

    2018-01-15

    A simple, green and effective extraction method, namely, pyridinium ionic liquid- (IL) based liquid-solid extraction (LSE), was first designed to extract the main inorganic and organic iodine compounds (I(-), monoiodo-tyrosine (MIT) and diiodo-tyrosine (DIT)). The optimal extraction conditions were as follows: ultrasonic intensity 100W, IL ([EPy]Br) concentration 200mM, extraction time 30min, liquid/solid ratio 10mL/g, and pH value 6.5. The morphologies of Laminaria were studied by scanning electron microscopy and transmission electron microscopy. The recovery values of I(-), MIT and DIT from Laminaria were in the range of 88% to 94%, and limits of detection were in the range of 59.40 to 283.6ng/g. The proposed method was applied to the extraction and determination of iodine compounds in three Laminaria. The results showed that IL-based LSE could be a promising method for rapid extraction of bioactive iodine from complex food matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Abnormal gas-liquid-solid phase transition behaviour of water observed with in situ environmental SEM.

    PubMed

    Chen, Xin; Shu, Jiapei; Chen, Qing

    2017-04-24

    Gas-liquid-solid phase transition behaviour of water is studied with environmental scanning electron microscopy for the first time. Abnormal phenomena are observed. At a fixed pressure of 450 Pa, with the temperature set to -7 °C, direct desublimation happens, and ice grows continuously along the substrate surface. At 550 Pa, although ice is the stable phase according to the phase diagram, metastable liquid droplets first nucleate and grow to ~100-200 μm sizes. Ice crystals nucleate within the large sized droplets, grow up and fill up the droplets. Later, the ice crystals grow continuously through desublimation. At 600 Pa, the metastable liquid grows quickly, with some ice nuclei floating in it, and the liquid-solid coexistence state exists for a long time. By lowering the vapour pressure and/or increasing the substrate temperature, ice sublimates into vapour phase, and especially, the remaining ice forms a porous structure due to preferential sublimation in the concave regions, which can be explained with surface tension effect. Interestingly, although it should be forbidden for ice to transform into liquid phase when the temperature is well below 0 °C, liquid like droplets form during the ice sublimation process, which is attributed to the surface tension effect and the quasiliquid layers.

  9. Abnormal gas-liquid-solid phase transition behaviour of water observed with in situ environmental SEM

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Shu, Jiapei; Chen, Qing

    2017-04-01

    Gas-liquid-solid phase transition behaviour of water is studied with environmental scanning electron microscopy for the first time. Abnormal phenomena are observed. At a fixed pressure of 450 Pa, with the temperature set to -7 °C, direct desublimation happens, and ice grows continuously along the substrate surface. At 550 Pa, although ice is the stable phase according to the phase diagram, metastable liquid droplets first nucleate and grow to ~100-200 μm sizes. Ice crystals nucleate within the large sized droplets, grow up and fill up the droplets. Later, the ice crystals grow continuously through desublimation. At 600 Pa, the metastable liquid grows quickly, with some ice nuclei floating in it, and the liquid-solid coexistence state exists for a long time. By lowering the vapour pressure and/or increasing the substrate temperature, ice sublimates into vapour phase, and especially, the remaining ice forms a porous structure due to preferential sublimation in the concave regions, which can be explained with surface tension effect. Interestingly, although it should be forbidden for ice to transform into liquid phase when the temperature is well below 0 °C, liquid like droplets form during the ice sublimation process, which is attributed to the surface tension effect and the quasiliquid layers.

  10. Direct molecular dynamics simulation of liquid-solid phase equilibria for a three-component plasma.

    PubMed

    Hughto, J; Horowitz, C J; Schneider, A S; Medin, Zach; Cumming, Andrew; Berry, D K

    2012-12-01

    The neutron-rich isotope ²²Ne may be a significant impurity in carbon and oxygen white dwarfs and could impact how the stars freeze. We perform molecular dynamics simulations to determine the influence of ²²Ne in carbon-oxygen-neon systems on liquid-solid phase equilibria. Both liquid and solid phases are present simultaneously in our simulation volumes. We identify liquid, solid, and interface regions in our simulations using a bond angle metric. In general we find good agreement for the composition of liquid and solid phases between our MD simulations and the semianalytic model of Medin and Cumming. The trace presence of a third component, neon, does not appear to strongly impact the chemical separation found previously for two-component carbon and oxygen systems. This suggests that small amounts of ²²Ne may not qualitatively change how the material in white dwarf stars freezes. However, we do find systematically lower melting temperatures (higher Γ) in our MD simulations compared to the semianalytic model. This difference seems to grow with impurity parameter Q_{imp} and suggests a problem with simple corrections to the linear mixing rule for the free energy of multicomponent solid mixtures that is used in the semianalytic model.

  11. Direct molecular dynamics simulation of liquid-solid phase equilibria for two-component plasmas.

    PubMed

    Schneider, A S; Hughto, J; Horowitz, C J; Berry, D K

    2012-06-01

    We determine the liquid-solid phase diagram for carbon-oxygen and oxygen-selenium plasma mixtures using two-phase molecular dynamics simulations. We identify liquid, solid, and interface regions using a bond angle metric. To study finite-size effects, we perform 27,648- and 55,296-ion simulations. To help monitor nonequilibrium effects, we calculate diffusion constants D(i). For the carbon-oxygen system we find that D(O) for oxygen ions in the solid is much smaller than D(C) for carbon ions and that both diffusion constants are 80 or more times smaller than diffusion constants in the liquid phase. There is excellent agreement between our carbon-oxygen phase diagram and that predicted by Medin and Cumming. This suggests that errors from finite-size and nonequilibrium effects are small and that the carbon-oxygen phase diagram is now accurately known. The oxygen-selenium system is a simple two-component model for more complex rapid proton capture nucleosynthesis ash compositions for an accreting neutron star. Diffusion of oxygen, in a predominantly selenium crystal, is remarkably fast, comparable to diffusion in the liquid phase. We find a somewhat lower melting temperature for the oxygen-selenium system than that predicted by Medin and Cumming. This is probably because of electron screening effects.

  12. Velocity of large bubble in liquid-solid mixture in a vertical tube

    SciTech Connect

    Hamaguchi, H.; Sakaguchi, T.

    1995-09-01

    The upward movement of a large bubble in a stationary mixture of liquid and solid is one of the most fundamental phenomena of gas-liquid-solid three phase slug flow in a vertical tube. The purpose of this study is to make clear the characteristic of the rising velocity of this fundamental flow experimentally. The rising velocity of a large bubble V in a liquid-solid mixture was measured and compared with the velocity V{sub o} in a liquid (without solid). The experimental results were correlated using a non-dimensional velocity V{sup *}(=V/V{sub o}), and the following results were obtained. It was found that the characteristic of the rising velocity differs according to the tube diameter and the liquid viscosity, or the Galileo number in the non-dimensional expression. It can be classified into two regimes. (i) When the liquid viscosity is large (or the tube diameter is small), V{sup *} decreases linearly against the volumetric solid fraction {epsilon} of the mixture. (ii) When the viscosity is small, on the other hand, the relation between V{sup *} and {epsilon} is not linear. This classification can be explained by the results in the previous papers by the authors dealing with a large bubble in a liquid.

  13. Gold catalyzed nickel disilicide formation: a new solid-liquid-solid phase growth mechanism.

    PubMed

    Tang, Wei; Picraux, S Tom; Huang, Jian Yu; Liu, Xiaohua; Tu, K N; Dayeh, Shadi A

    2013-01-01

    The vapor-liquid-solid (VLS) mechanism is the predominate growth mechanism for semiconductor nanowires (NWs). We report here a new solid-liquid-solid (SLS) growth mechanism of a silicide phase in Si NWs using in situ transmission electron microcopy (TEM). The new SLS mechanism is analogous to the VLS one in relying on a liquid-mediating growth seed, but it is fundamentally different in terms of nucleation and mass transport. In SLS growth of Ni disilicide, the Ni atoms are supplied from remote Ni particles by interstitial diffusion through a Si NW to the pre-existing Au-Si liquid alloy drop at the tip of the NW. Upon supersaturation of both Ni and Si in Au, an octahedral nucleus of Ni disilicide (NiSi2) forms at the center of the Au liquid alloy, which thereafter sweeps through the Si NW and transforms Si into NiSi2. The dissolution of Si by the Au alloy liquid mediating layer proceeds with contact angle oscillation at the triple point where Si, oxide of Si, and the Au alloy meet, whereas NiSi2 is grown from the liquid mediating layer in an atomic stepwise manner. By using in situ quenching experiments, we are able to measure the solubility of Ni and Si in the Au-Ni-Si ternary alloy. The Au-catalyzed mechanism can lower the formation temperature of NiSi2 by 100 °C compared with an all solid state reaction.

  14. True Vapor-Liquid-Solid Process Suppresses Unintentional Carrier Doping of Single Crystalline Metal Oxide Nanowires.

    PubMed

    Anzai, Hiroshi; Suzuki, Masaru; Nagashima, Kazuki; Kanai, Masaki; Zhu, Zetao; He, Yong; Boudot, Mickaël; Zhang, Guozhu; Takahashi, Tsunaki; Kanemoto, Katsuichi; Seki, Takehito; Shibata, Naoya; Yanagida, Takeshi

    2017-08-09

    Single crystalline nanowires composed of semiconducting metal oxides formed via a vapor-liquid-solid (VLS) process exhibit an electrical conductivity even without an intentional carrier doping, although these stoichiometric metal oxides are ideally insulators. Suppressing this unintentional doping effect has been a challenging issue not only for metal oxide nanowires but also for various nanostructured metal oxides toward their semiconductor applications. Here we demonstrate that a pure VLS crystal growth, which occurs only at liquid-solid (LS) interface, substantially suppresses an unintentional doping of single crystalline SnO2 nanowires. By strictly tailoring the crystal growth interface of VLS process, we found the gigantic difference of electrical conduction (up to 7 orders of magnitude) between nanowires formed only at LS interface and those formed at both LS and vapor-solid (VS) interfaces. On the basis of investigations with spatially resolved single nanowire electrical measurements, plane-view electron energy-loss spectroscopy, and molecular dynamics simulations, we reveal the gigantic suppression of unintentional carrier doping only for the crystal grown at LS interface due to the higher annealing effect at LS interface compared with that grown at VS interface. These implications will be a foundation to design the semiconducting properties of various nanostructured metal oxides.

  15. Determination of protein surface excess on a liquid/solid interface by single-molecule counting.

    PubMed

    Li, Nan; Tang, Hui; Gai, Hongwei; Dong, Xiuling; Wang, Qi; Yeung, Edward S

    2009-08-01

    Determination of protein surface excess is an important way of evaluating the properties of biomaterials and the characteristics of biosensors. A single-molecule counting method is presented that uses a standard fluorescence microscope to measure coverage of a liquid/solid interface by adsorbed proteins. The extremely low surface excess of lysozyme and bovine serum albumin (BSA), in a bulk concentration range from 0.3 nmol L(-1) (0.02 microg mL(-1)) to 3 nmol L(-1) (0.2 microg mL(-1)), were measured by recording the counts of spatially isolated single molecules on either hydrophilic (glass) or hydrophobic (polydimethylsiloxane, PDMS) surfaces at different pH. The differences observed in amounts of adsorbed proteins under different experimental conditions can be qualitatively explained by the combined interactions of electrostatic and hydrophobic forces. This, in turn, implies that single-molecule counting is an effective way of measuring surface coverage at a liquid/solid interface.

  16. Roles of Energy Dissipation in a Liquid-Solid Transition of Out-of-Equilibrium Systems

    NASA Astrophysics Data System (ADS)

    Komatsu, Yuta; Tanaka, Hajime

    2015-07-01

    Self-organization of active matter as well as driven granular matter in nonequilibrium dynamical states has attracted considerable attention not only from the fundamental and application viewpoints but also as a model to understand the occurrence of such phenomena in nature. These systems share common features originating from their intrinsically out-of-equilibrium nature, and how energy dissipation affects the state selection in such nonequilibrium states remains elusive. As a simple model system, we consider a nonequilibrium stationary state maintained by continuous energy input, relevant to industrial processing of granular materials by vibration and/or flow. More specifically, we experimentally study roles of dissipation in self-organization of a driven granular particle monolayer. We find that the introduction of strong inelasticity entirely changes the nature of the liquid-solid transition from two-step (nearly) continuous transitions (liquid-hexatic-solid) to a strongly discontinuous first-order-like one (liquid-solid), where the two phases with different effective temperatures can coexist, unlike thermal systems, under a balance between energy input and dissipation. Our finding indicates a pivotal role of energy dissipation and suggests a novel principle in the self-organization of systems far from equilibrium. A similar principle may apply to active matter, which is another important class of out-of-equilibrium systems. On noting that interaction forces in active matter, and particularly in living systems, are often nonconservative and dissipative, our finding may also shed new light on the state selection in these systems.

  17. Theoretical analysis of the vapor-liquid-solid mechanism of nanowire growth during molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.; Sibirev, N. V.; Cirlin, G. E.; Harmand, J. C.; Ustinov, V. M.

    2006-02-01

    A theoretical model of nanowire formation by the vapor-liquid-solid mechanism during molecular beam epitaxy and related growth techniques is presented. The model unifies the conventional adsorption-induced model, the diffusion-induced model, and the model of nucleation-mediated growth on the liquid-solid interface. The concentration of deposit atoms in the liquid alloy, the nanowire diameter, and all other characteristics of the growth process are treated dynamically as functions of the growth time. The model provides theoretical length-diameter dependences of nanowires and the dependence of the nanowire length on the technologically controlled growth conditions, such as the surface temperature and the deposition thickness. In particular, it is shown that the length-diameter curves of nanowires might convert from decreasing to increasing at a certain critical diameter and that the nanowires taper when their length becomes comparable with the adatom diffusion length on the sidewalls. The theoretical dependence of the nanowire morphology on its lateral size and length and on the surface temperature are compared to the available experimental data obtained recently for Si and GaAs nanowires.

  18. Direct molecular dynamics simulation of liquid-solid phase equilibria for a three-component plasma

    NASA Astrophysics Data System (ADS)

    Hughto, J.; Horowitz, C. J.; Schneider, A. S.; Medin, Zach; Cumming, Andrew; Berry, D. K.

    2012-12-01

    The neutron-rich isotope 22Ne may be a significant impurity in carbon and oxygen white dwarfs and could impact how the stars freeze. We perform molecular dynamics simulations to determine the influence of 22Ne in carbon-oxygen-neon systems on liquid-solid phase equilibria. Both liquid and solid phases are present simultaneously in our simulation volumes. We identify liquid, solid, and interface regions in our simulations using a bond angle metric. In general we find good agreement for the composition of liquid and solid phases between our MD simulations and the semianalytic model of Medin and Cumming. The trace presence of a third component, neon, does not appear to strongly impact the chemical separation found previously for two-component carbon and oxygen systems. This suggests that small amounts of 22Ne may not qualitatively change how the material in white dwarf stars freezes. However, we do find systematically lower melting temperatures (higher Γ) in our MD simulations compared to the semianalytic model. This difference seems to grow with impurity parameter Qimp and suggests a problem with simple corrections to the linear mixing rule for the free energy of multicomponent solid mixtures that is used in the semianalytic model.

  19. Capillary stability of vapor-liquid-solid crystallization processes and their comparison to Czochralski and Stepanov growth methods

    NASA Astrophysics Data System (ADS)

    Nebol'sin, Valery A.; Suyatin, Dmitry B.; Dunaev, Alexander I.; Tatarenkov, Alexander F.

    2017-04-01

    Epitaxial semiconductor nanowires grown with vapor-liquid-solid crystallization processes are very attractive nanoscale objects for many different applications. Despite extensive studies of the growth mechanism, there is still a lack of understanding of the growth process; in particular, the stability of the vapor-liquid-solid crystallization process has not previously been studied. Here we examine the capillary stability of the vapor-liquid-solid growth of nanowires and filamentary crystals with different diameters and demonstrate that the growth is stable for small Bond numbers when the meniscus height is linearly dependent on catalyst diameter. The capillary stability of vapor-liquid-solid growth is also compared with capillary stability in the Stepanov and Czochralski crystal growth methods; it is shown that capillary stability is not possible in the Czochralski method, although it is possible in the Stepanov growth method when the ratio of crystal diameter to shaper diameter is >1/2. These findings are important for better understanding and improved control of the growth of nanowires and filamentary crystals and indicate, for example, that large diameter filamentary crystals can be grown via a vapor-liquid-solid mechanism if the influence of gravity forces on the liquid catalytic particle shape can be reduced.

  20. Fluidization onset and expansion of gas-solid fluidized beds

    SciTech Connect

    Jones, O.C.; Shin, T.S.

    1984-08-01

    A simple, mass conservation-based, kinematic model is presented for accurately predicting both the onset of fluidization and the degree of (limit of) bed expansion in bubbling gas-solid fluidized beds. The model is consistant with inception correlations exisiting in the literature. Since the method has a sound physical basis, it might be expected to provide scaling between laboratory-scale fluidized beds and large-scale systems. This scaling ability, however, remains to be demonstrated as does the application to pressurized systems and where the terminal Reynolds numbers exceed 1000, (Archimedes numbers over about 3.2 x 10/sup 5/).

  1. 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.

  2. PREFACE: Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations

    NASA Astrophysics Data System (ADS)

    Gaigeot, Marie-Pierre; Sulpizi, Marialore

    2012-03-01

    Liquid-solid interfaces play an important role in a number of phenomena encountered in biological, chemical and physical processes. Surface-induced changes of the material properties are not only important for the solid support but also for the liquid itself. In particular, it is now well established that water at the interface is substantially different from bulk water, even in the proximity of apparently inert surfaces such as a simple metal. The complex chemistry at liquid-solid interfaces is typically fundamental to heterogeneous catalysis and electrochemistry, and has become especially topical in connection with the search for new materials for energy production. A quite remarkable example is the development of cheap yet efficient solar cells, whose basic components are dye molecules grafted to the surface of an oxide material and in contact with an electrolytic solution. In life science, the most important liquid-solid interfaces are the water-cell-membrane interfaces. Phenomena occurring at the surface of phospholipid bilayers control the docking of proteins, the transmission of signals as well as transport of molecules in and out of the cell. Recently the development of bio-compatible materials has lead to research on the interface between bio-compatible material and lipid/proteins in aqueous solution. Gaining a microscopic insight into the processes occurring at liquid-solid interfaces is therefore fundamental to a wide range of disciplines. This special section collects some contributions to the CECAM Workshop 'Liquid/Solid interfaces: Structure and Dynamics from Spectroscopy and Simulations' which took place in Lausanne, Switzerland in June 2011. Our main aim was to bring together knowledge and expertise from different communities in order to advance our microscopic understanding of the structure and dynamics of liquids at interfaces. In particular, one of our ambitions was to foster discussion between the experimental and theoretical

  3. Exploring the complexity of supramolecular interactions for patterning at the liquid-solid interface.

    PubMed

    Mali, Kunal S; Adisoejoso, Jinne; Ghijsens, Elke; De Cat, Inge; De Feyter, Steven

    2012-08-21

    The use of self-assembly to fabricate surface-confined adsorbed layers (adlayers) from molecular components provides a simple means of producing complex functional surfaces. The molecular self-assembly process relies on supramolecular interactions sustained by noncovalent forces such as van der Waals, electrostatic, dipole-dipole, and hydrogen bonding interactions. Researchers have exploited these noncovalent bonding motifs to construct well-defined two-dimensional (2D) architectures at the liquid-solid interface. Despite myriad examples of 2D molecular assembly, most of these early findings were serendipitous because the intermolecular interactions involved in the process are often numerous, subtle, cooperative, and multifaceted. As a consequence, the ability to tailor supramolecular patterns has evolved slowly. Insight gained from various studies over the years has contributed significantly to the knowledge of supramolecular interactions, and the stage is now set to systematically engineer the 2D supramolecular networks in a "preprogrammed" fashion. The control over 2D self-assembly of molecules has many important implications. Through appropriate manipulation of supramolecular interactions, one can "encode" the information at the molecular level via structural features such as functional groups, substitution patterns, and chiral centers which could then be retrieved, transferred, or amplified at the supramolecular level through well-defined molecular recognition processes. This ability allows for precise control over the nanoscale structure and function of patterned surfaces. A clearer understanding and effective use of these interactions could lead to the development of functional surfaces with potential applications in molecular electronics, chiral separations, sensors based on host-guest systems, and thin film materials for lubrication. In this Account, we portray our various attempts to achieve rational design of self-assembled adlayers by exploiting the

  4. Hydrogen storage as hydrides in a fixed or fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Bernis, A.; Storck, A.

    The results of experimental investigations of the performances of fixed and fluidized bed reactor configurations for hydride storage are reported. Constant -20 to 50 C temperatures and 0-10 bars pressures were examined. A membrane compressor was employed to circulate the hydrogen during fluidized bed tests. Measurements were made of the quantity of hydrogen absorbed and desorbed and the reaction speeds. The quality of the FeTi hydrides used, when industrial grade, adversely affected the purity of the gas. The reactions, being exothermic during hydrogenation, indicated that heat exchangers would be required in operation configurations. The desorption evacuation in the fluidized bed was accomplished 20-30 times faster than when using the fixed bed. Storage was also faster in the fluidized bed, which moderated the hydrogenation temperature rise. The expansion of the hydrides during hydrogenation and shrinkage during evacuation will be significant factors in the design of reactor shapes and sizes.

  5. Four utility fluidized-bed combustion projects approach demonstration status

    SciTech Connect

    Not Available

    1986-12-01

    Fluidized bed combustors (FBCs) are being considered as viable options in an increasing number of applications where new power plant capacity is required and for schemes to extend the lives of existing power plants by retrofitting. Four large demonstration projects have been organized to allow evaluation of variations of this technology on a scale where essentially full-size components are employed. These four projects are: a 125 MW(e) atmospheric pressure fluidized-bed combustor retrofitted to Unit 2 of the Black Dog Station of Northern States Power Company near St. Paul, Minnesota; a 110 MW(e) circulating fluidized bed combustor at the Nucla Station of the Colorado Ute Electric Association, Inc. at Nucla, Colorado; a 160 MW(e) at the Shawnee Station of the Tennessee Valley Authority (TVA) at Paducah, Kentucky; and a 70 MW(e) pressurized fluidized-bed combustor at the Tidd Station of the Ohio Power Company (of AEP) at Brilliant, Ohio. The design, fuel, and schedule for each project are described. 10 references.

  6. Computational and Experimental Study of Spherocylinder Particles in Fluidized Beds

    NASA Astrophysics Data System (ADS)

    Mahajan, Vinay; Kuipers, Hans; Padding, Johan; Multiphase Reactors Group, TU Eindhoven Team

    2016-11-01

    Non-spherical particle flows are often encountered in fluidized process equipment. A coupled computational fluid dynamics (CFD) and discrete element method(DEM) approach has been extensively applied in recent years to study these flows at the particle scale. However, most of these studies focus on spherical particles while in reality, the constituent particles are seldom spherical. Particle shape can significantly affect the hydrodynamical response in fluidized beds. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation of the particle, Reynolds number and packing fraction. In this work, a CFD-DEM approach has been extended to model a lab scale quasi-2D fluidized bed of spherocylinder (rod-like) particles. These particles can be classified as Geldart D particles and have an aspect ratio of 4. Numerical results for the pressure drop, bed height and solid circulation patterns are compared with results from a complementary laboratory experiment. We also present results on particle orientations close to the confining walls, which provides interesting insight regarding the particle alignment. Thus the capability of the CFD-DEM approach to efficiently account for global bed dynamics in fluidized bed of rod-like particle is demonstrated. This research work is funded by ERC Grant.

  7. Calculation of Liquid-Solid Interfacial Free Energy in Pb-Cu Binary Immiscible System

    NASA Astrophysics Data System (ADS)

    Li, Hong-shan; Zhou, Sheng-gang; Cao, Yong

    2016-11-01

    Based on the solid-liquid interfacial free energy theory of the complex Warren binary & pseudo-binary system and through the simplification of it by taking Pb-Cu binary system as an example, the physical model for it in binary immiscible system can be obtained. Next, its thermodynamic formula is derived to obtain a theoretical formula that only contains two parameters, and comparisons are made with regard to γSL calculated values and experimental values of MPE (multiphase equilibrium method) under several kinds of temperatures. As manifested in the outcomes, the improved physical model and theoretical formula will become not only easy to understand but also simple for calculation (the calculated value of γSL depends on two parameters, i.e. temperature and percentage composition of Cu atom). It can be treated as the foundation of application for the γSL calculation of liquid-solid interfacial free energy in other immiscible systems.

  8. Method and apparatus for acoustic plate mode liquid-solid phase transition detection

    DOEpatents

    Blair, Dianna S.; Freye, Gregory C.; Hughes, Robert C.; Martin, Stephen J.; Ricco, Antonio J.

    1993-01-01

    A method and apparatus for sensing a liquid-solid phase transition event is provided which comprises an acoustic plate mode detecting element placed in contact with a liquid or solid material which generates a high-frequency acoustic wave that is attenuated to an extent based on the physical state of the material is contact with the detecting element. The attenuation caused by the material in contact with the acoustic plate mode detecting element is used to determine the physical state of the material being detected. The method and device are particularly suited for detecting conditions such as the icing and deicing of wings of an aircraft. In another aspect of the present invention, a method is provided wherein the adhesion of a solid material to the detecting element can be measured using the apparatus of the invention.

  9. Pilot scale experiments of magnesia hydration under gas-liquid-solid (three-phase) reaction system

    NASA Astrophysics Data System (ADS)

    Tang, Xiaojia; Lv, Qiwei; Yin, Lin; Nie, Yixing; Jin, Qi; Ji, Yangyuan; Zhu, Yimin

    2017-08-01

    Pilot scale experiments were conducted to prepare magnesium hydroxide by magnesia hydration under gas-liquid-solid (three-phase) reaction system. The effect of reaction pressure, reactivity and particle size of magnesia and the concentration of the pulp on the degree of hydration was investigated. The results indicated that the hydration reaction occurred at the first 30min mainly. During the set reaction condition, degree of hydration of 68% could be obtained at the reaction pressure of 0.2MPa, concentration of pulp of 5%w/w with high reactivity and fine powder. The promotion effect on the degree of hydration caused by the three-phase reaction system was mostly attributed to the exfoliation of steam.

  10. Observation of total external reflection of x rays from a liquid-solid interface

    NASA Astrophysics Data System (ADS)

    Touryanski, A. G.; Pirshin, I. V.

    2007-07-01

    A new experimental scheme for the measurement of the x-ray reflectivity R from a liquid-solid interface in the range of angles of total external reflection is proposed. An x-ray beam is transmitted through a plane channel filled with a liquid under investigation. The channel is formed by two optically polished plates, one of which being the substrate under study. To eliminate the edge effects caused by surface tension, polymer films with a lyophilic coating are used as windows of the channel. For wate-silicon and glycerol-silicon interfaces, the angular dependences of R and the parameters of the interfaces are measured with the scheme developed using the CuK α (8.05 keV) and CuK β (8.91 keV) lines.

  11. Vapor-Liquid-Solid Etch of Semiconductor Surface Channels by Running Gold Nanodroplets

    PubMed Central

    Nikoobakht, Babak; Herzing, Andrew; Muramoto, Shin; Tersoff, Jerry

    2016-01-01

    We show that Au nanoparticles spontaneously move across the (001) surface of InP, InAs, and GaP when heated in the presence of water vapor. As they move, the particles etch crystallographically aligned grooves into the surface. We show that this process is a negative analog of the vapor-liquid-solid (VLS) growth of semiconductor nanowires: semiconductor dissolves into the catalyst, and reacts with water vapor at the catalyst surface to create volatile oxides, depleting the dissolved cations and anions and so sustaining the dissolution process. This VLS etching process provides a new tool for directed assembly of structures with sub-lithographic dimensions, as small as a few nanometers in diameter. Au particles above 100 nm in size do not exhibit this process but remain stationary, with oxide accumulating around the particles. PMID:26599639

  12. Method and apparatus for acoustic plate mode liquid-solid phase transition detection

    NASA Astrophysics Data System (ADS)

    Blair, D. S.; Frye, G. C.; Hughes, R. C.; Martin, S. J.; Ricco, A. J.

    1990-05-01

    A method and apparatus for sensing a liquid-solid phase transition event is provided which comprises an acoustic plate mode detecting element placed in contact with a liquid or solid material which generates a high-frequency acoustic wave that is attenuated to an extent based on the physical state of the material in contact with the detecting element. The attenuation caused by the material in contact with the acoustic plate mode detecting element is used to determine the physical state of the material being detected. The method and device are particularly suited for detecting conditions such as the icing and deicing of wings of an aircraft. In another aspect of the present invention, a method is provided wherein the adhesion of a solid material to the detecting element can be measured using the apparatus of the invention.

  13. Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires

    SciTech Connect

    Chen, Wanghua; Roca i Cabarrocas, Pere; Pareige, Philippe; Castro, Celia; Xu, Tao; Grandidier, Bruno; Stiévenard, Didier

    2015-09-14

    By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process.

  14. Analysis of vapor-liquid-solid mechanism in Au-assisted GaAs nanowire growth

    NASA Astrophysics Data System (ADS)

    Harmand, J. C.; Patriarche, G.; Péré-Laperne, N.; Mérat-Combes, M.-N.; Travers, L.; Glas, F.

    2005-11-01

    GaAs nanowires were grown by molecular-beam epitaxy on (111)B oriented surfaces, after the deposition of Au nanoparticles. Different growth durations and different growth terminations were tested. After the growth of the nanowires, the structure and the composition of the metallic particles were analyzed by transmission electron microscopy and energy dispersive x-ray spectroscopy. We identified three different metallic compounds: the hexagonal β'Au7Ga2 structure, the orthorhombic AuGa structure, and an almost pure Au face centered cubic structure. We explain how these different solid phases are related to the growth history of the samples. It is concluded that during the wire growth, the metallic particles are liquid, in agreement with the generally accepted vapor-liquid-solid mechanism. In addition, the analysis of the wire morphology indicates that Ga adatoms migrate along the wire sidewalls with a mean length of about 3μm.

  15. Studies of Ternary Surface Complexes at Liquid-Solid Interfaces in Seawater

    PubMed

    Zhengbin; Wei; Liansheng; Youjun; Zhijian

    1997-06-01

    The E (%)-pH curves of the ternary surface complexes at liquid-solid interfaces in the simulated seawater system of alpha-FeOOH-Cu(II)-tryptophan were determined. The diffuse reflectance IR spectra of the species at the solid surfaces in the above ternary equilibration system were examined. The above two results were comparatively studied. It is shown that the coadsorption of Cu(II) and tryptophan on alpha-FeOOH surface results in the formation of the ternary surface complex. Cu(II) can promote the exchange adsorption of tryptophan on alpha-FeOOH surface. The diffuse reflectance IR spectra can give us some evidence for the structure of the ternary surface complex, and these results are in accordance with the results of the E (%)-pH curves.

  16. Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism

    SciTech Connect

    Zervos, M. Giapintzakis, J.; Mihailescu, C. N.; Luculescu, C. R.; Florini, N.; Komninou, Ph.; Kioseoglou, J.; Othonos, A.

    2014-05-01

    Indium tin oxide nanowires were grown by the reaction of In and Sn with O{sub 2} at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In{sub 2}O{sub 3} nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO{sub 2} and suppression of In{sub 2}O{sub 3} permitting compositional and structural tuning from SnO{sub 2} to In{sub 2}O{sub 3} which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

  17. Liquid-solid phase transition of hydrogen and deuterium in silica aerogel

    NASA Astrophysics Data System (ADS)

    Van Cleve, E.; Worsley, M. A.; Kucheyev, S. O.

    2014-10-01

    Behavior of hydrogen isotopes confined in disordered low-density nanoporous solids remains essentially unknown. Here, we use relaxation calorimetry to study freezing and melting of H2 and D2 in an ˜85%-porous base-catalyzed silica aerogel. We find that liquid-solid transition temperatures of both isotopes inside the aerogel are depressed. The phase transition takes place over a wide temperature range of ˜4 K and non-trivially depends on the liquid filling fraction, reflecting the broad pore size distribution in the aerogel. Undercooling is observed for both H2 and D2 confined inside the aerogel monolith. Results for H2 and D2 are extrapolated to tritium-containing hydrogens with the quantum law of corresponding states.

  18. Ab initio study on the dynamics of furfural at the liquid-solid interfaces

    NASA Astrophysics Data System (ADS)

    Dang, Hongli; Xue, Wenhua; Shields, Darwin; Liu, Yingdi; Jentoft, Friederike; Resasco, Daniel; Wang, Sanwu

    2013-03-01

    Catalytic biomass conversion sometimes occurs at the liquid-solid interfaces. We report ab initio molecular dynamics simulations at finite temperatures for the catalytic reactions involving furfural at the water-Pd and water-Cu interfaces. We found that, during the dynamic process, the furan ring of furfural prefers to be parallel to the Pd surface and the aldehyde group tends to be away from the Pd surface. On the other hand, at the water-Cu(111) interface, furfural prefers to be tilted to the Cu surface while the aldehyde group is bonded to the surface. In both cases, interaction of liquid water and furfural is identified. The difference of dynamic process of furfural at the two interfaces suggests different catalytic reaction mechanisms for the conversion of furfural, consistent with the experimental investigations. Supported by DOE (DE-SC0004600). Simulations and calculations were performed on XSED's and NERSC's supercomputers

  19. Oscillatory Mass Transport in Vapor-Liquid-Solid Growth of Sapphire Nanowires

    SciTech Connect

    Oh, Sang Ho; Chisholm, Matthew F; Kauffmann, Yaron; Kaplan, Prof. Wayne D.; Luo, Weidong; Ruhle, M.; Scheu, Christina

    2010-01-01

    In vapor-liquid-solid (VLS) growth, the liquid phase plays a pivotal role in mediating mass transport from the vapor source to the growth front of a nanowire. Such transport often takes place through the liquid phase. However, we observed by in situ transmission electron microscopy a different behavior for self-catalytic VLS growth of sapphire nanowires. The growth occurs in a layer-by-layer fashion and is accomplished by interfacial diffusion of oxygen through the ordered liquid aluminum atoms. Oscillatory growth and dissolution reactions at the top rim of the nanowires occur and supply the oxygen required to grow a new (0006) sapphire layer. A periodic modulation of the VLS triple-junction configuration accompanies these oscillatory reactions.

  20. Colloidal GaAs quantum wires: solution-liquid-solid synthesis and quantum-confinement studies.

    PubMed

    Dong, Angang; Yu, Heng; Wang, Fudong; Buhro, William E

    2008-05-07

    Colloidal GaAs quantum wires with diameters of 5-11 nm and narrow diameter distributions (standard deviation = 12-21% of the mean diameter) are grown by two methods based on the solution-liquid-solid (SLS) mechanism. Resolved excitonic absorption features arising from GaAs quantum wires are detected, allowing extraction of the size-dependent effective band gaps of the wires. The results allow the first systematic comparison of the size dependences of the effective band gaps in corresponding sets of semiconductor quantum wires and quantum wells. The GaAs quantum wire and well band gaps scale according to the prediction of a simple effective-mass-approximation, particle-in-a-box (EMA-PIB) model, which estimates the kinetic confinement energies of electron-hole pairs in quantum nanostructures of different shapes and confinement dimensionalities.

  1. Joule-Thomson Inversion in Vapor-Liquid-Solid Solution Systems

    NASA Astrophysics Data System (ADS)

    Nichita, Dan Vladimir; Pauly, Jerome; Daridon, Jean-Luc

    2009-07-01

    Solid phase precipitation can greatly affect thermal effects in isenthalpic expansions; wax precipitation may occur in natural hydrocarbon systems in the range of operating conditions, the wax appearance temperature being significantly higher (as high as 350 K) for hyperbaric fluids. Recently, methods for calculating the Joule-Thomson inversion curve (JTIC) for two-phase mixtures, and for three-phase vapor-liquid-multisolid systems have been proposed. In this study, an approach for calculating the JTIC for the vapor-liquid-solid solution systems is presented. The JTIC is located by tracking extrema and angular points of enthalpy departure variations versus pressure at isothermal conditions. The proposed method is applied to several complex synthetic and naturally occurring hydrocarbon systems. The JTIC can exhibit several distinct branches (which may lie within two- or three-phase regions or follow phase boundaries), multiple inversion temperatures at fixed pressure, as well as multiple inversion pressures at given temperature.

  2. Fluidized bed combustor modeling

    NASA Technical Reports Server (NTRS)

    Horio, M.; Rengarajan, P.; Krishnan, R.; Wen, C. Y.

    1977-01-01

    A general mathematical model for the prediction of performance of a fluidized bed coal combustor (FBC) is developed. The basic elements of the model consist of: (1) hydrodynamics of gas and solids in the combustor; (2) description of gas and solids contacting pattern; (3) kinetics of combustion; and (4) absorption of SO2 by limestone in the bed. The model is capable of calculating the combustion efficiency, axial bed temperature profile, carbon hold-up in the bed, oxygen and SO2 concentrations in the bubble and emulsion phases, sulfur retention efficiency and particulate carry over by elutriation. The effects of bed geometry, excess air, location of heat transfer coils in the bed, calcium to sulfur ratio in the feeds, etc. are examined. The calculated results are compared with experimental data. Agreement between the calculated results and the observed data are satisfactory in most cases. Recommendations to enhance the accuracy of prediction of the model are suggested.

  3. 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

  4. 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

  5. Scanning tunneling microscopy study of molecular order at liquid-solid interfaces

    NASA Astrophysics Data System (ADS)

    Magonov, S. N.; Wawkuschewski, A.; Cantow, H.-J.; Liang, W.; Whangbo, M.-H.

    1994-08-01

    Adsorbates of normal alkane C36H74, cycloalkanes (CH2)48 and (CH2)72, decanol C10H21OH, 4-hexyl-4'-CyanoBiphenyl (6CB) and 4-octyl-4t'-CyanoBiphenyl (8CB) on graphite and β-Nb3I8 were studied by Scanning Tunneling Microscopy (STM), and the molecular arrangements at the liquid-solid interface were examined. Large-scale STM images show that the adsorbates possess complex multilayered structures, and that molecular ordering at the liquid-solid interfaces occurs primarily in the immediate vicinity of the substrate. Molecular-scale STM images are primarily determined by the electronic contributions of the most protruded atoms of the topmost overlayer. The underlying overlayers and the substrate affect the images indirectly by perturbing the topography of the topmost overlayer. The STM images of the adsorbates on graphite show that the atomically flat surface of graphite leads organic molecules to form lamella-like structures, while on the grooved surface of β-Nb3I8, long chain-like molecules are trapped in the grooves. We were unable to image the cycloalkanes on β-Nb3I8, which suggests that the cycloalkanes cannot assemble on the grooved surface due to a mismatch between the molecular shape and surface topography. The layers of 6CB and 8CB adsorbed on β-Nb3I8 exhibit two types of domains, which may be related to how the grooves of the β-Nb3I8 surface are occupied by the organic molecules. The STM images of decanol adsorbed on β-Nb3I8 show two domains of different brightness. The relative brightness of these domains switches reversibly as the gap resistance is changed in the region around -60 MΩ.

  6. Pulse enhanced fluidized bed combustion

    SciTech Connect

    Mueller, B.; Golan, L.; Toma, M.; Mansour, M.

    1996-12-31

    Various technologies are available for the combustion of high-sulfur, high-ash fuels, particularly coal. From performance, economic and environmental standpoints, fluidized bed combustion (FBC) is the leading candidate for utilization of high sulfur coals. ThermoChem, Inc., and the South Carolina Energy Research and Development Center (SCERDC) are installing a hybrid fluidized bed combustion system at Clemson University. This hybrid system, known as the Pulsed Atmospheric Fluidized Bed Combustor (PAFBC), will augment the University`s steam system by providing 50--60,000 lbs/hr of saturated process steam. The PAFBC, developed by Manufacturing and Technology Conversion International, Inc., (MTCI), integrates a pulse combustor with a bubbling-bed-type atmospheric fluidized bed coal combustor. The pulse combustion system imparts an acoustic effect that enhances combustion efficiency, SO{sub 2} capture, low NO{sub x} emissions, and heat transfer efficiency in the fluidized bed. These benefits of pulse combustion result in modestly sized PAFBC units with high throughput rates and lower costs when compared to conventional fluidized bed units.

  7. Particle pressures in fluidized beds

    SciTech Connect

    Campbell, C.S.; Rahman, K.; Hu, X.; Jin, C.; Potapov, A.V.

    1992-01-01

    This is an experimental project to make detailed measurements of the particle pressures generated in fluidized beds. The focus lies in two principle areas: (1) the particle pressure distribution around single bubbles rising in a two-dimensional gas-fluidized bed and (2) the particle pressures measured in liquid-fluidized beds. This first year has largely been to constructing the experiments The design of the particle pressure probe has been improved and tested. A two-dimensional gas-fluidized bed has been constructed in order to measure the particle pressure generated around injected bubbles. The probe is also being adapted to work in a liquid fluidized bed. Finally, a two-dimensional liquid fluidized bed is also under construction. Preliminary measurements show that the majority of the particle pressures are generated in the wake of a bubble. However, the particle pressures generated in the liquid bed appear to be extremely small. Finally, while not directly associated with the particle pressure studies, some NERSC supercomputer time was granted alongside this project. This is being used to make large scale computer simulation of the flow of granular materials in hoppers.

  8. Atmospheric fluidized bed combustion gas erosion solution

    SciTech Connect

    Seitzinger, D.L.

    1995-12-31

    The Westwood Generating Station is a 30 MW, anthracite culm-fired plant located near Joliet, Pennsylvania. The culm firing technology is based on the Combustion Engineering-Lurgi circulating fluidized bed combustion (CFBC) technology first introduced in this country in boiler applications in the mid-80`s. This unit went into commercial operation In July 1988 and is the second of its type in service in this country. It is located on the original site of the Westwood Colliery that was in operation from 1920 to 1950 preparing anthracite coal for the commercial market and leaving behind a 15 year fuel supply of anthracite culm, a coal screening waste, that is now the fuel for this station. This paper documents the investigations and corrective actions taken to stop severe tube erosion encountered in the combustor and heat recovery surfaces of the unit. This erosion is attributed to high gas velocities due to changing operation requirements and gas flow distribution.

  9. Reducing static charges in fluidized bed reactions

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Ballou, E. V.; Wood, P. C.; Spitze, L. A.

    1980-01-01

    Radio frequency glow discharge apparatus ionizes fluidizing gas, making it conductive enough to neutralize static charge on fluidized particles. Particles agglomerate less, and in one case reactant loading capacity was increased six fold.

  10. 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)

  11. Characteristics of fluidized-packed beds

    NASA Technical Reports Server (NTRS)

    Gabor, J. D.; Mecham, W. J.

    1968-01-01

    Study of fluidized-packed bed includes investigation of heat transfer, solids-gas mixing, and elutriation characteristics. A fluidized-packed bed is a system involving the fluidization of small particles in the voids of a packed bed of larger nonfluidized particles.

  12. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, Juhani

    1996-01-01

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

  13. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, J.

    1996-03-19

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

  14. Formation of Multicomponent Star Structures at the Liquid/Solid Interface.

    PubMed

    Tahara, Kazukuni; Kaneko, Kyohei; Katayama, Keisuke; Itano, Shintaro; Nguyen, Chi Huan; Amorim, Deborah D D; De Feyter, Steven; Tobe, Yoshito

    2015-06-30

    To demonstrate key roles of multiple interactions between multiple components and multiple phases in the formation of an uncommon self-assembling pattern, we present here the construction of a porous hexagonal star (h-star) structure using a trigonal molecular building block at the liquid/solid interface. For this purpose, self-assembly of hexaalkoxy-substituted dehydrobenzo[12]annulene derivatives DBA-OCns was investigated at the tetradecane/graphite interface by means of scanning tunneling microscopy (STM). Monolayer structures were significantly influenced by coadsorbed tetradecane molecules depending on the alkyl chains length (C13-C16) of DBA-OCn. However, none of DBA-OCn molecules formed the expected trigonal complexes, indicating that an additional driving force is necessary for the formation of the trigonal complex and its assembly into the h-star structure. As a first approach, we employed the "guest induced structural change" for the formation of the h-star structure. In the presence of two guest molecules, nonsubstituted DBA and hexakis(phenylethynyl)benzene which fit the respective pores, an h-star structure was formed by DBA-OC15 at the tetradecane/graphite interface. Moreover, a tetradecane molecule was coadsorbed between a pair of alkyl chains of DBA-OC15, thereby blocking the interdigitation of the alkyl chain pairs. Therefore, the h-star structure results from the self-assembly of the four molecular components including the solvent molecule. The second approach is based on aggregation of perfluoroalkyl chains via fluorophilicity of DBA-F, in which the perfluoroalkyl groups are substituted at the end of three alkyl chains of DBA-OCn via p-phenylene linkers. A trigonal complex consisting of DBA-F and three tetradecane molecules formed an h-star structure, in which the perfluoroalkyl groups that orient into the alkane solution phase aggregated at the hexagonal pore via fluorophilicity. The present result provides useful insight into the design and

  15. Flow-Solution-Liquid-Solid Growth of Semiconductor Nanowires: A Novel Approach for Controlled Synthesis

    SciTech Connect

    Hollingsworth, Jennifer A.; Palaniappan, Kumaranand; Laocharoensuk, Rawiwan; Smith, Nickolaus A.; Dickerson, Robert M.; Casson, Joanna L.; Baldwin, Jon K.

    2012-06-07

    Semiconductor nanowires (SC-NWs) have potential applications in diverse technologies from nanoelectronics and photonics to energy harvesting and storage due to their quantum-confined opto-electronic properties coupled with their highly anisotropic shape. Here, we explore new approaches to an important solution-based growth method known as solution-liquid-solid (SLS) growth. In SLS, molecular precursors are reacted in the presence of low-melting metal nanoparticles that serve as molten fluxes to catalyze the growth of the SC-NWs. The mechanism of growth is assumed to be similar to that of vapor-liquid-solid (VLS) growth, with the clear distinctions of being conducted in solution in the presence of coordinating ligands and at relatively lower temperatures (<300 C). The resultant SC-NWs are soluble in common organic solvents and solution processable, offering advantages such as simplified processing, scale-up, ultra-small diameters for quantum-confinement effects, and flexible choice of materials from group III-V to groups II-VI, IV-VI, as well as truly ternary I-III-VI semiconductors as we recently demonstrates. Despite these advantages of SLS growth, VLS offers several clear opportunities not allowed by conventional SLS. Namely, VLS allows sequential addition of precursors for facile synthesis of complex axial heterostructures. In addition, growth proceeds relatively slowly compared to SLS, allowing clear assessments of growth kinetics. In order to retain the materials and processing flexibility afforded by SLS, but add the elements of controlled growth afforded by VLS, we transformed SLS into a flow based method by adapting it to synthesis in a microfluidic system. By this new method - so-called 'flow-SLS' (FSLS) - we have now demonstrated unprecedented fabrication of multi-segmented SC-NWs, e.g., 8-segmented CdSe/ZnSe defined by either compositionally abrupt or alloyed interfaces as a function of growth conditions. In addition, we have studied growth rates as a

  16. Interfacial Dynamics in Liquid-Solid Mixtures: A Study of Solidification and Coarsening

    NASA Astrophysics Data System (ADS)

    Gibbs, John W.

    The microstructural evolution of liquid-solid mixtures is examined using X-ray computed tomography to make in-situ, 4D (three spatial dimensions and time) measurements of the interfaces between the liquid and solid phases. Samples are a variety of hypo-eutectic Al-Cu alloys and the total characterized volume is approximately 1 mm3. The coarsening datasets span solid volume fractions of 30% to 80% and have durations of up to 15 hours, making them some of the largest, most comprehensive coarsening datasets. This data is used show that the solid fraction does not have a significant effect on the coarsening rate, unlike in a system of spherical particles. The interfacial curvature and velocity data that is made possible by the 4D measurements is used to develop a relationship between interface shape and the average normal velocity for a piece of interface with that shape. This model accounts for both capillarity and shape-related diffusional effects. Neighborhood related diffusional effects lead to a distribution in velocities about the mean; these distributions are examined and shown to follow a Gaussian distribution. A novel new data collection and processing algorithm for X-ray computed tomography, time-interlaced model-based iterative reconstruction, is used to achieve 4D data with micrometer level spatial resolution and 1.8 second temporal resolution. This is approximately an order of magnitude better than what has been achieved before and yields the first data with sufficient spatial and temporal resolutions to characterize the microstructure during solidification. The resulting data of dendritic growth in an Al-24wt%Cu alloy that is being cooled at 2°C/minute shows the formation of split tip secondary dendrite arms that have not been seen before in transparent organic analogues. A single free-growing dendrite is isolated from this data and analyzed as a function of distance from the tip, resulting in relationships for the volume of solid, Vs proportional to

  17. Lignite air-steam gasification in the fluidized bed of iron-containing slag catalysts

    SciTech Connect

    Kuznetsov, B.N.; Shchipko, M.L.; Golovin, Yu.

    1995-12-01

    The influence of fluidized bed of iron-containing slag particles on air-steam gasification of powdered Kansk-Achinsk lignite in entrained flow was studied in pilot installation with productivity about 60 kg per hour. Slag of Martin process and boiler slag were used as catalytic active materials until their complete mechanical attrition. Two following methods of catalytic gasification of lignite were compared: the partial gasification in stationary fluidized bed of slag particles with degree of fuel conversion 40-70% and complete gasification in circulating bed of slag particles. In the first case only the most reactive part of fuel is gasified with the simultaneously formation of porous carbon residue with good sorption ability. It was found the catalytic fluidized bed improves heat transfer from combustion to reduction zone of gas-generator and increases the rate of fuel conversion at the temperature range 900-1000{degrees}C. At these temperatures the degree of conversion is depended considerably on the duration time of fuel particles in the catalytic fluidized bed. The influence of catalytic fluidized bed height and velocity of reaction mixture on the temperature profiles in the gas-generator was studied. The optimal relationship was found between the fluidized bed height and velocity of flow which makes possible to produce the gas with higher calorific value at maximum degree of fuel conversion.

  18. Experimental study of large-scale pulsations of a fluidized bed

    SciTech Connect

    Glinskii, V.A.; Protod'yakonov, I.O.; Chesnokov, Yu.G.

    1980-01-01

    In experimental investigations of the hydrodynamics of fluidized beds, study of large- and small-scale pulsations of the most important characteristics of the fluidized bed: voidage, hydraulic resistance, velocities of the gaseous and solid phases, etc., is of considerable interest. The character of these pulsations is determined by the heterogeneity of the structure of the fluidized bed, due to the presence of channels, bubbles, stagnant zones, and circulation currents. The object of the present work was experimental study of fluctuations of the height h of the surface of a fluidized bed, with simultaneous recording of the corresponding fluctuations of the hydraulic resistance ..delta..P of the bed. The existence of a direct connection between large-scale pulsations of the hydraulic resistance ..delta..P of the fluidized bed and large-scale pulsations of the bed height h is demonstrated in the paper. It is proved on this basis that large-scale pulsations of h and ..delta..P can be described by equations of the same type. The coefficients of the equation are determined from experimental data on pulsations, and its solutions for different fluidization regimes are analyzed.

  19. 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.

  20. Observations of the liquid/solid interface in low-gravity melting

    NASA Technical Reports Server (NTRS)

    Otto, G. H.; Lacy, L. L.

    1974-01-01

    Time-lapsed photography of the liquid/solid interface of a melting ice cylinder was taken on Skylab 3 over a period of three hours. The same experiment was simulated on earth such that morphological and thermodynamic differences could be noted. A study of the returned color film clearly shows the dominance of surface tension effects in low-gravity melting. In the Skylab experiment, the ends of the ice cylinder melted first with the water being driven by surface tension onto the cylindrical surfaces. At any time, the principle of minimum surface area governs the overall appearance of the water-ice globule which changed from a cylindrical to a spherical shape. The latent heat of melting in low-gravity is supplied only by radiation (81%) and conduction (19%); whereas in one-g, the convective (55%) and radiative (38%) mode of heat transfer dominates over the conductive portion (7%). Information is also provided on containerless melting and heat transfer in space in the absence of convective air currents.

  1. Fine-Grid Eulerian Simulation of Sedimenting Particles: Liquid-Solid and Gas-Solid Systems

    NASA Astrophysics Data System (ADS)

    Zaheer, Muhammad; Hamid, Adnan; Ullah, Atta

    2017-06-01

    A computational study of mono-dispersed spherical sedimenting particles was performed with Eulerian two-fluid model (TFM). The aim was to investigate the applicability and accuracy of TFM with proper closure laws from kinetic theory of granular flow (KTGF) for sedimentation studies. A three-dimensional cubical box with full periodic boundaries was employed. The volume fraction of particles (ϕs) was varied from very low (ϕs = 0.01) to dense regimes (ϕs = 0.4), for two different types of fluids, i.e., gas and liquid. It is observed that the results for liquid-solid sedimentation are in good agreement with simulation studies and experimental correlation of Richardson and Zaki. However, for gas-solid system, results show different behavior at low volume fractions, which is more pronounced with increasing Stokes number. This can be attributed to inhomogeneous distribution of solid particles in gas phase at dilute concentrations, which causes meso-scale clusters and streamers formation. It is concluded that the ratio of density of particles to density of fluid which appears in Stokes number plays critical role in settling behavior of particles.

  2. Nickel oxide nanowires: vapor liquid solid synthesis and integration into a gas sensing device.

    PubMed

    Kaur, N; Comini, E; Zappa, D; Poli, N; Sberveglieri, G

    2016-05-20

    In the field of advanced sensor technology, metal oxide nanostructures are promising materials due to their high charge carrier mobility, easy fabrication and excellent stability. Among all the metal oxide semiconductors, nickel oxide (NiO) is a p-type semiconductor with a wide band gap and excellent optical, electrical and magnetic properties, which has not been much investigated. Herein, we report the growth of NiO nanowires by using the vapor liquid solid (VLS) technique for gas sensing applications. Platinum, palladium and gold have been used as a catalyst for the growth of NiO nanowires. The surface morphology of the nanowires was investigated through scanning electron microscopy to find out which catalyst and growth conditions are best for the growth of nanowires. GI-XRD and Raman spectroscopies were used to confirm the crystalline structure of the material. Different batches of sensors have been prepared, and their sensing performances towards different gas species such as carbon monoxide, ethanol, acetone and hydrogen have been explored. NiO nanowire sensors show interesting and promising performances towards hydrogen.

  3. Low temperature homoepitaxy of GaN structures by Vapor Liquid Solid transport

    NASA Astrophysics Data System (ADS)

    Jaud, Alexandre; Auvray, Laurent; Kahouli, Abdelkarim; Abi-Tannous, Tony; Linas, Sébastien; Ferro, Gabriel; Brylinski, Christian

    2017-06-01

    Low temperature (500-800 °C) homoepitaxy of not intentionally doped GaN structures on GaN(0 0 0 1)/Si(1 1 1) seed has been investigated by Vapor-Liquid-Solid (VLS) approach. The growth sequence consists in the metalorganic chemical vapor deposition of a network of submicrometric liquid Ga droplets, followed by their nitridation under flowing ammonia diluted either in H2 or Ar. When nitridation is performed under Ar carrier gas, GaN growth is very difficult to control due to too high N supersaturation within the droplets, despite very low NH3 flows. Nucleation and growth at the droplets periphery are always favored and, in most cases, high growth rates induce a crust-like growth, forming hollow GaN gangues. The use of H2 as carrier gas is detrimental to GaN (seed and grown material) stability, for nitridation temperatures ≥700 °C. But, compared to Ar atmosphere, a pronounced decrease of N supersaturation is demonstrated, allowing a better control of the growth mode. This is probably a consequence of a lower thermal decomposition efficiency of NH3 at the droplets surface. Optimal growth conditions are found at relatively low temperature (600 °C) and NH3 flow (20 sccm) for which a network of well-separated and faceted epitaxial GaN dots or rings is obtained. The growth mechanisms allowing these results are discussed.

  4. Observations of the liquid/solid interface in low-gravity melting

    NASA Technical Reports Server (NTRS)

    Otto, G. H.; Lacy, L. L.

    1974-01-01

    Time-lapsed photography of the liquid/solid interface of a melting ice cylinder was taken on Skylab 3 over a period of three hours. The same experiment was simulated on earth such that morphological and thermodynamic differences could be noted. A study of the returned color film clearly shows the dominance of surface tension effects in low-gravity melting. In the Skylab experiment, the ends of the ice cylinder melted first with the water being driven by surface tension onto the cylindrical surfaces. At any time, the principle of minimum surface area governs the overall appearance of the water-ice globule which changed from a cylindrical to a spherical shape. The latent heat of melting in low-gravity is supplied only by radiation (81%) and conduction (19%); whereas in one-g, the convective (55%) and radiative (38%) mode of heat transfer dominates over the conductive portion (7%). Information is also provided on containerless melting and heat transfer in space in the absence of convective air currents.

  5. Ultralow liquid/solid friction in carbon nanotubes: comprehensive theory for alcohols, alkanes, OMCTS, and water.

    PubMed

    Falk, Kerstin; Sedlmeier, Felix; Joly, Laurent; Netz, Roland R; Bocquet, Lydéric

    2012-10-09

    In this work, we perform a theoretical study of liquid flow in graphitic nanopores of different sizes and geometries. Molecular dynamics flow simulations of different liquids (water, decane, ethanol, and OMCTS) in carbon nanotubes (CNT) are shown to exhibit flow velocities 1-3 orders of magnitude higher than those predicted from the continuum hydrodynamics framework and the no-slip boundary condition. These results support previous experimental findings obtained by several groups that reported exceptionally high liquid flow rates in CNT membranes. The liquid/graphite friction coefficient is identified as the crucial parameter for this fast mass transport in CNT. The friction coefficient is found to be very sensitive to wall curvature: friction is independent of confinement for liquids between flat graphene walls with zero curvature, whereas it decreases with increasing positive curvature (liquid inside CNT), and it increases with increasing negative curvature (liquid outside CNT). Furthermore, we present a theoretical approximate expression for the friction coefficient, which predicts qualitatively and semiquantitatively its curvature dependent behavior. The proposed theoretical description, which works well for different kinds of liquids (alcohols, alkanes, and water), sheds light on the physical mechanisms at the origin of the ultra low liquid/solid friction in CNT. In fact, it is due to their perfectly ordered molecular structure and their atomically smooth surface that carbon nanotubes are quasiperfect liquid conductors compared to other membrane pores like nanochannels in amorphous silica.

  6. [Refolding of reduced/denatured RNase A the hydrophobic liquid-solid interface].

    PubMed

    Bi, Jing; Bai, Quan; Wang, Jun; Wang, Lili

    2010-08-01

    The renaturation of the reduced/denatured RNase A on the hydrophobic liquid-solid interface was investigated using hydrophobic interaction chromatography (HIC). The effects of urea concentrations, the ratios of reduced and oxidized glutathiones (GSH and GSSG), the pH of mobile phase and protein concentrations on the refolding efficiency and mass recovery of the reduced/denatured RNase A were investigated in detail. The results indicated that the reduced/ denatured RNase A can be refolded completely under the optimized conditions of pH 8.0, 2.0 mol/L urea and the concentration ratio of GSH/GSSG of 8: 1 in mobile phase. When the denatured protein was at the concentration of 5.0 mg/mL, the bioactivity efficiency and mass recoveries were 98.0% and 61.9% for 8.0 mol/L urea-denatured RNase A, respectively; and 100.1% and 66.8% for 7.0 mol/L guanidine hydrochloride (GuaHCl)-denatured RNase A, respectively. It proves that HIC is a powerful tool and new approach for protein refolding.

  7. Nickel oxide nanowires: vapor liquid solid synthesis and integration into a gas sensing device

    NASA Astrophysics Data System (ADS)

    Kaur, N.; Comini, E.; Zappa, D.; Poli, N.; Sberveglieri, G.

    2016-05-01

    In the field of advanced sensor technology, metal oxide nanostructures are promising materials due to their high charge carrier mobility, easy fabrication and excellent stability. Among all the metal oxide semiconductors, nickel oxide (NiO) is a p-type semiconductor with a wide band gap and excellent optical, electrical and magnetic properties, which has not been much investigated. Herein, we report the growth of NiO nanowires by using the vapor liquid solid (VLS) technique for gas sensing applications. Platinum, palladium and gold have been used as a catalyst for the growth of NiO nanowires. The surface morphology of the nanowires was investigated through scanning electron microscopy to find out which catalyst and growth conditions are best for the growth of nanowires. GI-XRD and Raman spectroscopies were used to confirm the crystalline structure of the material. Different batches of sensors have been prepared, and their sensing performances towards different gas species such as carbon monoxide, ethanol, acetone and hydrogen have been explored. NiO nanowire sensors show interesting and promising performances towards hydrogen.

  8. Gold Nanoparticles Assisted Silicon Nanowire Growth using Vapor Liquid Solid Method

    NASA Astrophysics Data System (ADS)

    Surawijaya, A.; Anshori, I.; Rohiman, A.; Idris, I.

    2011-12-01

    Silicon Nanowires (SiNWs) are promising 1D semiconductor nanostructures which are intensively researched in many countries due to its potential applications in various fields such as MOSFET channel, and/or wiring, solar cells, chemical and biological sensors. We used gold nanoparticles (AuNPs) which has low eutectic temperature, such as a metal catalyst in Vapor Liquid Solid (VLS) method to grow SiNW on top of Silicon <100> substrates. AuNPs are synthesized using Turkevich method and then deposited on the Silicon substrate using dip coating method. To grow SiNWs, we placed the sample inside a Low Pressure Chemical Vapor Deposition (LPCVD) reactor with temperature around the Si-Au eutectic temperature (˜500 °C), after the temperature is stable we flowed Silane (SiH4) gas diluted in Nitrogen gas to the chamber for several minutes. We found that the SiNWs are grown with AuNPs as the nanowire cap on the top of it. SiNWs have an average length around 500-800 nm with diameter proportional to its gold catalyst. By optimizing the growth parameter, we aim to achieve vertical SiNWs that can be used for practical devices such as chemical sensors.

  9. n-Type Doping of Vapor-Liquid-Solid Grown GaAs Nanowires.

    PubMed

    Gutsche, Christoph; Lysov, Andrey; Regolin, Ingo; Blekker, Kai; Prost, Werner; Tegude, Franz-Josef

    2011-12-01

    In this letter, n-type doping of GaAs nanowires grown by metal-organic vapor phase epitaxy in the vapor-liquid-solid growth mode on (111)B GaAs substrates is reported. A low growth temperature of 400°C is adjusted in order to exclude shell growth. The impact of doping precursors on the morphology of GaAs nanowires was investigated. Tetraethyl tin as doping precursor enables heavily n-type doped GaAs nanowires in a relatively small process window while no doping effect could be found for ditertiarybutylsilane. Electrical measurements carried out on single nanowires reveal an axially non-uniform doping profile. Within a number of wires from the same run, the donor concentrations ND of GaAs nanowires are found to vary from 7 × 10(17) cm(-3) to 2 × 10(18) cm(-3). The n-type conductivity is proven by the transfer characteristics of fabricated nanowire metal-insulator-semiconductor field-effect transistor devices.

  10. Directed synthesis of germanium oxide nanowires by vapor-liquid-solid oxidation.

    PubMed

    Gunji, M; Thombare, S V; Hu, S; McIntyre, P C

    2012-09-28

    We report on the directed synthesis of germanium oxide (GeO(x)) nanowires (NWs) by locally catalyzed thermal oxidation of aligned arrays of gold catalyst-tipped germanium NWs. During oxygen anneals conducted above the Au-Ge binary eutectic temperature (T > 361 °C), one-dimensional oxidation of as-grown Ge NWs occurs by diffusion of Ge through the Au-Ge catalyst droplet, in the presence of an oxygen containing ambient. Elongated GeO(x) wires grow from the liquid catalyst tip, consuming the adjoining Ge NWs as they grow. The oxide NWs' diameter is dictated by the catalyst diameter and their alignment generally parallels that of the growth direction of the initial Ge NWs. Growth rate comparisons reveal a substantial oxidation rate enhancement in the presence of the Au catalyst. Statistical analysis of GeO(x) nanowire growth by ex situ transmission electron microscopy and scanning electron microscopy suggests a transition from an initial, diameter-dependent kinetic regime, to diameter-independent wire growth. This behavior suggests the existence of an incubation time for GeO(x) NW nucleation at the start of vapor-liquid-solid oxidation.

  11. Effect of catalyst diameter on vapour-liquid-solid growth of GaAs nanowires

    SciTech Connect

    O'Dowd, B. J. Shvets, I. V.; Wojtowicz, T.; Kolkovsky, V.; Wojciechowski, T.; Zgirski, M.; Rouvimov, S.; Liu, X.; Pimpinella, R.; Dobrowolska, M.; Furdyna, J.

    2014-08-14

    GaAs nanowires were grown on (111)B GaAs substrates using the vapour-liquid-solid mechanism. The Au/Pt nanodots used to catalyse wire growth were defined lithographically and had varying diameter and separation. An in-depth statistical analysis of the resulting nanowires, which had a cone-like shape, was carried out. This revealed that there were two categories of nanowire present, with differing height and tapering angle. The bimodal nature of wire shape was found to depend critically on the diameter of the Au-Ga droplet atop the nanowire. Transmission electron microscopy analysis also revealed that the density of stacking faults in the wires varied considerably between the two categories of wire. It is believed that the cause of the distinction in terms of shape and crystal structure is related to the contact angle between the droplet and the solid-liquid interface. The dependency of droplet diameter on contact angle is likely related to line-tension, which is a correction to Young's equation for the contact angle of a droplet upon a surface. The fact that contact angle may influence resulting wire structure and shape has important implications for the planning of growth conditions and the preparation of wires for use in proposed devices.

  12. Many-body dissipative particle dynamics simulation of liquid/vapor and liquid/solid interactions

    NASA Astrophysics Data System (ADS)

    Arienti, Marco; Pan, Wenxiao; Li, Xiaoyi; Karniadakis, George

    2011-05-01

    The combination of short-range repulsive and long-range attractive forces in many-body dissipative particle dynamics (MDPD) is examined at a vapor/liquid and liquid/solid interface. Based on the radial distribution of the virial pressure in a drop at equilibrium, a systematic study is carried out to characterize the sensitivity of the surface tension coefficient with respect to the inter-particle interaction parameters. For the first time, the approximately cubic dependence of the surface tension coefficient on the bulk density of the fluid is evidenced. In capillary flow, MDPD solutions are shown to satisfy the condition on the wavelength of an axial disturbance leading to the pinch-off of a cylindrical liquid thread; correctly, no pinch-off occurs below the cutoff wavelength. Moreover, in an example that illustrates the cascade of fluid dynamics behaviors from potential to inertial-viscous to stochastic flow, the dynamics of the jet radius is consistent with the power law predictions of asymptotic analysis. To model interaction with a solid wall, MDPD is augmented by a set of bell-shaped weight functions; hydrophilic and hydrophobic behaviors, including the occurrence of slip in the latter, are reproduced using a modification in the weight function that avoids particle clustering. The dynamics of droplets entering an inverted Y-shaped fracture junction is shown to be correctly captured in simulations parametrized by the Bond number, confirming the flexibility of MDPD in modeling interface-dominated flows.

  13. Kinetics of liquid-solid phase transition in large nickel clusters

    NASA Astrophysics Data System (ADS)

    Yakubovich, Alexander V.; Sushko, Gennady; Schramm, Stefan; Solov'yov, Andrey V.

    2013-07-01

    In this paper, we have explored computationally the solidification process of a nickel cluster consisting of 2057 atoms. This process has the characteristic features of the first-order phase transition occurring in a finite system. The focus of our research is placed on the elucidation of correlated dynamics of a large ensemble of particles in the course of the nanoscale liquid-solid phase transition through the computation and analysis of the results of molecular dynamics (MD) simulations with the corresponding theoretical model. This problem is of significant interest and importance because the controlled dynamics of systems on the nanoscale is one of the central topics in the development of modern nanotechnologies. MD simulations in large molecular systems are rather computer power demanding. Therefore, in order to advance with MD simulations, we have used modern computational methods based on the graphics processing units (GPUs). The advantages of the use of GPUs for MD simulations in comparison with the CPUs are demonstrated and benchmarked. The reported speedup reaches factors greater than 400. This work opens a path towards exploration with the use of MD of a larger number of scientific problems inaccessible earlier with the CPU-based computational technology.

  14. Controlled Growth of Organic Semiconductor Films Using Electrospray Vapor-Liquid-Solid Deposition

    NASA Astrophysics Data System (ADS)

    Shaw, Daniel; Bufkin, Kevin; Johnson, Brad; Patrick, David

    2010-03-01

    Interest in low molecular weight organic semiconductors (OS) for applications such as light-emitting diodes, photovoltaics, and other technologies stems in part from their prospects for enabling significantly reduced manufacturing costs compared to traditional inorganic semiconductors. However many of the best performing prototype devices produced so far have involved expensive or time-consuming fabrication methods, such as the use of single crystals or thin films deposited under high vacuum conditions. New methods are needed capable of rapidly and inexpensively producing high quality polycrystalline films, preferably involving near-ambient conditions. This poster will present studies of one such approach based on an electrospray vapor-liquid-solid growth technique. The method produces polycrystalline OS films deposited via atmospheric-pressure sublimation from a carrier gas (argon) which is partially ionized by a corona discharge. Vapor-phase molecules are then attracted to a charged substrate coated with a thin liquid solvent layer, in which they dissolve and grow as crystals, producing films with large grain sizes. This poster will describe the electrostatic and hydrodynamic features of the deposition mechanism, and the growth kinetics of the resulting polycrystalline films.

  15. Organic-vapor-liquid-solid deposition with an impinging gas jet

    NASA Astrophysics Data System (ADS)

    Shaw, Daniel W.; Bufkin, Kevin; Baronov, Alexandr A.; Johnson, Brad L.; Patrick, David L.

    2012-04-01

    A method for rapid, mass-efficient deposition of highly crystalline organic films under near ambient conditions of pressure and temperature is reported based on delivery of an organic precursor via an impinging gas jet to a substrate coated by a thin liquid solvent layer. Films of the organic semiconductor tetracene were deposited by sublimation into a flow of argon carrier gas directed at an indium-tin-oxide/glass substrate coated by a thin layer of bis(2-ethylhexyl)sebecate, and growth was followed in situ with optical microscopy. A fluid dynamics model is applied to account for the gas phase transport and aggregation, and the results compared to experiment. The combination of gas jet delivery with an organic-vapor-liquid-solid growth mechanism leads to larger crystals and lower nucleation densities than on bare surfaces, with markedly different nucleation and growth kinetics. An explanation based on enhanced solution-phase diffusivity and a larger critical nucleus size in the liquid layer is proposed to account for the differences.

  16. Chemistry at the square nanometer: reactivity at liquid/solid interfaces revealed with an STM.

    PubMed

    Münninghoff, Joris A W; Elemans, Johannes A A W

    2017-02-02

    For more than three decades the scanning tunnelling microscope (STM) has proven to be an indispensable tool to image molecules adsorbed at a surface at the highest detail possible. In addition to simply imaging molecules, STM can also be applied to monitor dynamic surface phenomena, including chemical reactions. By studying reactions at a surface at the single molecule level, unique information about reaction mechanisms can be obtained which remains hidden when conventional ensemble techniques are used. Many STM studies of chemical reactions have been performed in extreme environments like ultrahigh vacuum or high pressure chambers, but these are far removed from conditions in which most chemical and biological processes take place, i.e., in a liquid at ambient atmospheres. This feature paper highlights the developments in the relatively unexplored research area of investigating chemical reactions with an STM at a liquid/solid interface under ambient conditions. Covalent couplings between molecules, light-induced isomerisations, reactions under electrochemical control, and complex multistep processes and catalysis are discussed.

  17. Rational Concept for Reducing Growth Temperature in Vapor-Liquid-Solid Process of Metal Oxide Nanowires.

    PubMed

    Zhu, Zetao; Suzuki, Masaru; Nagashima, Kazuki; Yoshida, Hideto; Kanai, Masaki; Meng, Gang; Anzai, Hiroshi; Zhuge, Fuwei; He, Yong; Boudot, Mickaël; Takeda, Seiji; Yanagida, Takeshi

    2016-12-14

    Vapor-liquid-solid (VLS) growth process of single crystalline metal oxide nanowires has proven the excellent ability to tailor the nanostructures. However, the VLS process of metal oxides in general requires relatively high growth temperatures, which essentially limits the application range. Here we propose a rational concept to reduce the growth temperature in VLS growth process of various metal oxide nanowires. Molecular dynamics (MD) simulation theoretically predicts that it is possible to reduce the growth temperature in VLS process of metal oxide nanowires by precisely controlling the vapor flux. This concept is based on the temperature dependent "material flux window" that the appropriate vapor flux for VLS process of nanowire growth decreases with decreasing the growth temperature. Experimentally, we found the applicability of this concept for reducing the growth temperature of VLS processes for various metal oxides including MgO, SnO2, and ZnO. In addition, we show the successful applications of this concept to VLS nanowire growths of metal oxides onto tin-doped indium oxide (ITO) glass and polyimide (PI) substrates, which require relatively low growth temperatures.

  18. 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.

  19. Distributor for multistage fluidized beds

    SciTech Connect

    Wormser, A.

    1992-06-16

    This patent describes a multibed fluidized bed system. It comprises a fluidized bed vessel having a casing surrounding a first distributor and a second distributor downstream from the first distributor; a first bed material placed on the first distributor and a second bed material placed on the second distributor; each of the bed materials having an angle of repose; and wherein the angle formed by the substantially straight elongated tubular passages and the upper surface is less than the angle of repose of the second bed material.

  20. Pressurized fluidized bed combustion ash management options

    SciTech Connect

    Bland, A.E.; Brown, T.H.; Young, L.J.; Wheeldon, J.M.

    1995-12-31

    Pressurized fluidized bed combustion (PFBC) of coal is undergoing demonstration and commercial deployment in the United States, as well as throughout the world. American Electric Power`s (AEP) bubbling PFBC 70 MW{sub e} Tidd demonstration program in Ohio and pilot-scale work at Ahlstrom Pyropower`s 10 MW{sub e} circulating PFBC at Karhula, Finland have demonstrated the advantages of PFBC technology. Development of uses for solid wastes from PFBC coal conversion systems is being actively pursued as part of the commercial demonstration of PFBC technologies. Ash collected from the low-sulfur subbituminous coal-fired Ahlstrom pilot circulating PFBC tests in Karhula, Finland 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). Ash use options evaluated for these PFBC ashes were construction-related applications, such as (1) cement production, (2) fills and embankment, (3) soil stabilization, (4) synthetic aggregate production, as well as an amendment for acidic and sodic soil and mine spoil.

  1. Pulsed atmospheric fluidized bed combustion. Final report

    SciTech Connect

    Not Available

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  2. Development and elaboration of numerical method for simulating gas-liquid-solid three-phase flows based on particle method

    NASA Astrophysics Data System (ADS)

    Takahashi, Ryohei; Mamori, Hiroya; Yamamoto, Makoto

    2016-02-01

    A numerical method for simulating gas-liquid-solid three-phase flows based on the moving particle semi-implicit (MPS) approach was developed in this study. Computational instability often occurs in multiphase flow simulations if the deformations of the free surfaces between different phases are large, among other reasons. To avoid this instability, this paper proposes an improved coupling procedure between different phases in which the physical quantities of particles in different phases are calculated independently. We performed numerical tests on two illustrative problems: a dam-break problem and a solid-sphere impingement problem. The former problem is a gas-liquid two-phase problem, and the latter is a gas-liquid-solid three-phase problem. The computational results agree reasonably well with the experimental results. Thus, we confirmed that the proposed MPS method reproduces the interaction between different phases without inducing numerical instability.

  3. Catalyst-assisted vapor-liquid-solid growth of single-crystal Ga2O3 nanobelts.

    PubMed

    Zhang, Jun; Jiang, Feihong; Yang, Yongdong; Li, Jianping

    2005-07-14

    Mass production of quasi-one-dimensional gallium oxide nanobelts is accomplished through graphite-thermal reduction of a mixture of gallium oxide powders and SnO2 nanopowders under controlled experimental conditions. Sn nanoparticles are located at or close to the tips of the nanobelts and served as the catalyst for the nanobelt growth by a vapor-liquid-solid mechanism. The morphology and microstructure of the nanobelts were characterized by scanning electron microscopy and high-resolution transmission electron microscopy. The Ga2O3 nanobelts grow along the [104] direction, the widths ranged from several tens to several hundreds of nanometers, and the lengths ranged from several tens to several hundreds of micrometers. The growth of Ga2O3 nanobelts is initiated by Sn nanoparticles via a catalyst-assisted vapor-liquid-solid process, which makes it possible to control the sizes of Ga2O3 nanobelts.

  4. Adsorption kinetics of surfactants at liquid-solid and liquid-vapor interfaces from atomic-scale simulations

    NASA Astrophysics Data System (ADS)

    Iskrenova, Eugeniya K.; Patnaik, Soumya S.

    2012-02-01

    Nucleate pool boiling of pure liquid is a complex process involving different size- and time-scale phenomena. The appearance of the first nanobubble in the liquid at the bottom of a hot pan, the detachment of the bubble from the solid surface, its subsequent coalescence with other bubbles, all represent complex multiscale phenomena. Surfactants added to water increase the complexity of the process by contributing to the dynamic surface tension at the liquid-vapor and liquid-solid interfaces and thus affecting the heat and mass transfer at those interfaces. We apply molecular dynamics simulations to study the adsorption kinetics of anionic, cationic, and non-ionic surfactants at liquid/solid and liquid/vapor interfaces. The all-atom vs. united-atom approaches for the solid and surfactants are surveyed in view of their applicability at near boiling temperatures and a range of model water potentials is assessed for reproducing the thermal properties of water at boiling conditions.

  5. Fluidizing device for solid particulates

    DOEpatents

    Diebold, J.P.; Scahill, J.W.

    A flexible whip suspended in a hopper is caused to impact against fibrous and irregularly shaped particulates in the hopper to fluidize the particulates and facilitate the flow of the particulates through the hopper. The invention provides for the flow of particulates at a substantially constant mass flow rate and uses a minimum of energy.

  6. 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.

  7. Analysis of the gas states at a liquid/solid interface based on interactions at the microscopic level.

    PubMed

    Li, Zhaoxia; Zhang, Xuehua; Zhang, Lijuan; Zeng, Xiaocheng; Hu, Jun; Fang, Haiping

    2007-08-09

    The states of gas accumulated at the liquid/solid interface are analyzed on the basis of the continuum theory, in which the Hamaker constant is used to describe the long-range interaction at the microscopic scale. The Hamaker constant is always negative, whereas the "gas" spreading coefficient can be either negative or positive. Despite the complexity of gas, including that the density profile may not be uniform due to absorption on both solid and liquid surfaces, we predict three possible gas states at the liquid/solid interface, that is, complete "wetting", partial "wetting", and pseudopartial "wetting". These possible gas states correspond, respectively, to a gas pancake (or film) surrounded by a wet solid, a gas bubble with a finite contact angle, and a gas bubble(s) coexisting with a gas pancake. The typical thickness of the gas pancakes is at the nano scale within the force range of the long-range interaction, whereas the radius of the gas bubbles can be large. The state of a gas bubble(s) coexisting with a gas film is predicted theoretically for the first time. Our theoretical results can contribute to the development of a unified picture of gas nucleation at the liquid/solid interface.

  8. Self-catalytic solution-liquid-liquid-solid (SLLS) growth of tapered SnS nanorods

    NASA Astrophysics Data System (ADS)

    Cho, Ki-Hyun; Sung, Yun-Mo

    2013-04-01

    Taper-shaped SnS nanorods were synthesized via mild chemistry, and the self-catalytic solution-liquid-liquid-solid (SLLS) process was proposed as a crystal growth mechanism. There exists a distinct difference in our SLLS growth compared to the well-known SLS growth in that we injected Sn precursors into a hot trioctylphosphine sulfide (TOPS) solution, which is a reverse process of the general SLS growth. This reverse process could prevent the oxidation of Sn precursors and thus it could facilitate the growth of SnS nanorods, since the surface of Sn clusters and droplets could be momentarily passivated by TOPS molecules. Without addition of extra catalyst nanoparticles, the nucleation and growth of SnS nanorods was induced by liquid Sn droplets. Spherical Sn tips existing at the top of the nanorods evidence the self-catalytic growth. The SLLS growth was proposed based upon the large Sn clusters existing at the bottom of the SnS nanorods in an intermediate stage (5 s) of the growth and the tapered morphology of the nanorods. The growth of SnS nanorods could progress by the upward diffusion of Sn atoms from large liquid Sn clusters along the surface of the SnS nanorods to the interfacial liquid layers (neck area) and the diffusion of S decomposed from TOPS in the solution to the neck area. SnS nanorods showed a direct energy band gap of ~1.6 eV, determined by using the Kubelka-Munk transformation of UV-visible spectra. This self-catalytic SLLS growth produced high-quality and single crystalline SnS nanorods within only 15 s at 290 °C.Taper-shaped SnS nanorods were synthesized via mild chemistry, and the self-catalytic solution-liquid-liquid-solid (SLLS) process was proposed as a crystal growth mechanism. There exists a distinct difference in our SLLS growth compared to the well-known SLS growth in that we injected Sn precursors into a hot trioctylphosphine sulfide (TOPS) solution, which is a reverse process of the general SLS growth. This reverse process could

  9. Pulsed atmospheric fluidized-bed combustor development. Environmental Assessment

    SciTech Connect

    Not Available

    1992-05-01

    Pulsed atmospheric fluidized-bed combustion (PAFBC) is a unique and innovative coal-fueled technology that has the potential to meet these conditions and provide heat and/or process steam to small industrial, commercial, institutional and residential complexes. The potential of Pulse Atmospheric Fluidized Bed Combustion (PAFBC) technology has been amply demonstrated under the sponsorship of a previous DOE/METC contract (DE-AC21-88MC25069). The environmental performance of a coal-fired laboratory-scale system (1.5 million British Thermal Units per hour) (MMBtu/hr) significantly surpassed that of conventional bubbling and circulating fluidized-bed combustion units (see Table 1 for performance comparison). Prompted by these encouraging results in combustion, sulfur capture, emissions control, and enhanced heat transfer, Island Creek Coal Company (ICC) and Baltimore Thermal Energy Corporation expressed interest in the technology and offered to participate by providing host sites for field testing. EA`s have been submitted independently for each of these field test sites. This submission addresses the preliminary testing of the PAFBC unit at Manufacturing and Technology Conversion International`s (MTCI) Baltimore, MD facility.

  10. 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.

  11. Alkene/diamond liquid/solid interface characterization using internal photoemission spectroscopy.

    PubMed

    Nebel, C E; Shin, D; Takeuchi, D; Yamamoto, T; Watanabe, H; Nakamura, T

    2006-06-20

    The photochemical attachment of 10-amino-dec-1-ene molecules protected with a trifluoroacetic acid group (TFAAD) on hydrogen-terminated single-crystalline chemical vapor deposited (CVD) diamond is characterized by total photoyield spectroscopy (TPYS), conductivity, Hall-effect, spectrally resolved photoconductivity (SPC), optical transmission experiments, and, for the first time, by in situ internal photoemission (IPE) spectroscopy applied in the spectral regime from 4 to 6 eV on the alkene/diamond (liquid/solid) heterostructures. These experiments are performed on undoped, (100) oriented, single-crystalline CVD diamond films, which contain no grain boundaries and have negligible bulk and surface defect densities. X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical bonding of alkene molecules to diamond. The spectroscopic set of data shows that the photochemical reaction window of H-terminated diamond is shifted below the optical gap of diamond because of the negative electron affinity. In situ IPE experiments reveal electron emission between 4.5 and 5.2 eV. A model is introduced and discussed in which valence-band electrons are optically excited into empty hydrogen-induced surface states of diamond from where they tunnel into empty pi states of alkene molecules. We theoretically discuss the fastest attachment time to achieve a saturated TFAAD layer of about 2 x 10(14) cm(-)(2) on diamond, which is experimentally detected to be 7 h. In the case of direct optical electron excitations from diamond, the bonding efficiency will be one TFAAD molecule attachment arising from about 1600 emitted electrons.

  12. Hydroxyapatite kinetic deposition on solid substrates induced by laser-liquid-solid interaction

    NASA Astrophysics Data System (ADS)

    Pramatarova, Liliana; Pecheva, Emilia; Petrov, Todor; Presker, Radina; Stutzmann, Martin

    2005-04-01

    Hydroxyapatite (HA) is present in the human body as a mineral constituent of the bones and teeth, as well as a major or minor component of kidney stones. HA deposited on different solid substrates can find applications including biomaterials and biosensors. This work deals with the kinetics of the HA growth by applying a novel method of laser-liquid-solid-interaction (LLSI) process on three types of materials (stainless stell, silicon and silica glass). The method allows interaction between a pulsed laser and a substrate immersed in a solution (simulated body fluid, SBF). By a scanning system, a design of seven squares at a distance of 200 μm was created at the end of each sample. In this way the center of the substrate (about 6x6 mm) was no irradiated. Following the LLSI process, the samples were left in the irradiated SBF for various intervals of time. Light microscopy (LM) showed surfaces seede with randomly distributed transparent and white particles. The surface seeding increased with the immersion time and was dependent on the substrate type. Fourier transform infrared (FTIR) spectrsocopy showed that in the first stage of soaking (up to 6 h) the observed white particles were calcium phosphate containing. Energy dispersive X-ray (EDX) spectrsocopy revealed that the transparent particles were NaCl. In the next stage (after 12 h) vibrational modes typical for HA were clearly observed. Detailed observation with scanning electron microscopy (SEM) after 12 h showed morphology of sphere-like aggregates, grouped in a porous network. Raman spectroscopy, X-ray diffraction (XRD) and EDX confirmed that after 12 h the grown layer was HA. It was found that in comparison to the traditionally empoyed prolonged soaking in SBF, the applied LLSI process yielded a synergistic effect due to the simultaneous use of the solid substrate, the aqueous solution and the laser energy.

  13. Kinetics of liquid-solid reactions in naphthenic acid conversion and Kraft pulping

    NASA Astrophysics Data System (ADS)

    Yang, Ling

    Two liquid-solid reactions, in which the morphology of the solid changes as the reactions proceeds, were examined. One is the NA conversion in oil by decarboxylation on metal oxides and carbonates, and the other is the Kraft pulping in which lignin removal by delignification reaction. In the study of the NA conversion, CaO was chosen as the catalyst for the kinetic study from the tested catalysts based on NA conversion. Two reaction mixtures, carrier oil plus commercial naphthenic acids and heavy vacuum gas oil (HVGO) from Athabasca bitumen, were applied in the kinetic study. The influence of TAN, temperature, and catalyst loading on the NA conversion and decarboxylation were studied systematically. The results showed that the removal rate of TAN and the decarboxylation of NA were both independent of the concentration of NA over the range studied, and significantly dependent on reaction temperature. The data from analyzing the spent catalyst demonstrated that calcium naphthenate was an intermediate of the decarboxylation reaction of NA, and the decomposition of calcium naphthenate was a rate-determining step. In the study on the delignification of the Kraft pulping, a new mechanism was proposed for the heterogeneous delignification reaction during the Kraft pulping process. In particular, the chemical reaction mechanism took into account the heterogeneous nature of Kraft pulping. Lignin reacted in parallel with sodium hydroxide and sodium sulfide. The mechanism consists of three key kinetic steps: (1) adsorption of hydroxide and hydrosulfide ions on lignin; (2) surface reaction on the solid surface to produce degraded lignin products; and (3) desorption of degradation products from the solid surface. The most important step for the delignification process is the surface reaction, rather than the reactions occurring in the liquid phase. A kinetic model has, thus, been developed based on the proposed mechanism. The derived kinetic model showed that the mechanism

  14. Self-catalytic solution-liquid-liquid-solid (SLLS) growth of tapered SnS nanorods.

    PubMed

    Cho, Ki-Hyun; Sung, Yun-Mo

    2013-05-07

    Taper-shaped SnS nanorods were synthesized via mild chemistry, and the self-catalytic solution-liquid-liquid-solid (SLLS) process was proposed as a crystal growth mechanism. There exists a distinct difference in our SLLS growth compared to the well-known SLS growth in that we injected Sn precursors into a hot trioctylphosphine sulfide (TOPS) solution, which is a reverse process of the general SLS growth. This reverse process could prevent the oxidation of Sn precursors and thus it could facilitate the growth of SnS nanorods, since the surface of Sn clusters and droplets could be momentarily passivated by TOPS molecules. Without addition of extra catalyst nanoparticles, the nucleation and growth of SnS nanorods was induced by liquid Sn droplets. Spherical Sn tips existing at the top of the nanorods evidence the self-catalytic growth. The SLLS growth was proposed based upon the large Sn clusters existing at the bottom of the SnS nanorods in an intermediate stage (5 s) of the growth and the tapered morphology of the nanorods. The growth of SnS nanorods could progress by the upward diffusion of Sn atoms from large liquid Sn clusters along the surface of the SnS nanorods to the interfacial liquid layers (neck area) and the diffusion of S decomposed from TOPS in the solution to the neck area. SnS nanorods showed a direct energy band gap of ∼1.6 eV, determined by using the Kubelka-Munk transformation of UV-visible spectra. This self-catalytic SLLS growth produced high-quality and single crystalline SnS nanorods within only 15 s at 290 °C.

  15. GREENHOUSE GAS EMISSIONS CONTROL BY OXYGEN FIRING IN CIRCULATING FLUIDIZED BED BOILERS: PHASE II--PILOT SCALE TESTING AND UPDATED PERFORMANCE AND ECONOMICS FOR OXYGEN FIRED CFB WITH CO2 CAPTURE

    SciTech Connect

    Nsakala ya Nsakala; Gregory N. Liljedahl; David G. Turek

    2004-10-27

    Because fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic CO{sub 2} emissions. In this Phase II study, ALSTOM Power Inc. (ALSTOM) has investigated one promising near-term coal fired power plant configuration designed to capture CO{sub 2} from effluent gas streams for sequestration. Burning fossil fuels in mixtures of oxygen and recirculated flue gas (made principally of CO{sub 2}) essentially eliminates the presence of atmospheric nitrogen in the flue gas. The resulting flue gas is comprised primarily of CO{sub 2}, along with some moisture, nitrogen, oxygen, and trace gases like SO{sub 2} and NO{sub x}. Oxygen firing in utility scale Pulverized Coal (PC) fired boilers has been shown to be a more economical method for CO{sub 2} capture than amine scrubbing (Bozzuto, et al., 2001). Additionally, oxygen firing in Circulating Fluid Bed Boilers (CFB's) can be more economical than in PC or Stoker firing, because recirculated gas flow can be reduced significantly. Oxygen-fired PC and Stoker units require large quantities of recirculated flue gas to maintain acceptable furnace temperatures. Oxygen-fired CFB units, on the other hand, can accomplish this by additional cooling of recirculated solids. The reduced recirculated gas flow with CFB plants results in significant Boiler Island cost savings resulting from reduced component The overall objective of the Phase II workscope, which is the subject of this report, is to generate a refined technical and economic evaluation of the Oxygen fired CFB case (Case-2 from Phase I) utilizing the information learned from pilot-scale testing of this concept. The objective of the pilot-scale testing was to generate detailed technical data needed to establish advanced CFB design requirements and performance when firing coals and

  16. 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.

  17. Internal Combustion Engines as Fluidized Bed Reactors

    NASA Astrophysics Data System (ADS)

    Lavich, Zoe; Taie, Zachary; Menon, Shyam; Beckwith, Walter; Daly, Shane; Halliday, Devin; Hagen, Christopher

    2016-11-01

    Using an internal combustion engine as a chemical reactor could provide high throughput, high chemical conversion efficiency, and reactant/product handling benefits. For processes requiring a solid catalyst, the ability to develop a fluidized bed within the engine cylinder would allow efficient processing of large volumes of fluid. This work examines the fluidization behavior of particles in a cylinder of an internal combustion engine at various engine speeds. For 40 micron silica gel particles in a modified Megatech Mark III transparent combustion engine, calculations indicate that a maximum engine speed of about 60.8 RPM would result in fluidization. At higher speeds, the fluidization behavior is expected to deteriorate. Experiments gave qualitative confirmation of the analytical predictions, as a speed of 48 RPM resulted in fluidized behavior, while a speed of 171 RPM did not. The investigation shows that under certain conditions a fluidized bed can be obtained within an engine cylinder. Corresponding Author.

  18. 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.

  19. Evaluation of wall boundary condition parameters for gas-solids fluidized bed simulations

    SciTech Connect

    Li, Tingwen; Benyahia, Sofiane

    2013-10-01

    Wall boundary conditions for the solids phase have significant effects on numerical predictions of various gas-solids fluidized beds. Several models for the granular flow wall boundary condition are available in the open literature for numerical modeling of gas-solids flow. In this study, a model for specularity coefficient used in Johnson and Jackson boundary conditions by Li and Benyahia (AIChE Journal, 2012, 58, 2058-2068) is implemented in the open-source CFD code-MFIX. The variable specularity coefficient model provides a physical way to calculate the specularity coefficient needed by the partial-slip boundary conditions for the solids phase. Through a series of 2-D numerical simulations of bubbling fluidized bed and circulating fluidized bed riser, the model predicts qualitatively consistent trends to the previous studies. Furthermore, a quantitative comparison is conducted between numerical results of variable and constant specularity coefficients to investigate the effect of spatial and temporal variations in specularity coefficient.

  20. 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.

  1. Development of videogrammetry as a tool for gas-particle fluidization research.

    PubMed

    Anweiler, S

    2017-03-21

    Many industries use fluidization of solid particles for energy efficiency or environmental friendly process development, and this paper introduces research techniques developed for investigating gas-particle systems At present there is plenty of room for refining gas-particle fluidization process. With the rapidly rising application of mathematical modelling, real time visualization of processes will be widely used for validation of those models in the near future. In presented research, photogrammetry, as a part of close range vision metrology, has been expanded to allow dynamic space and time analysis of the phase concentration distribution inside fluidization devices. A novel videogrammetry method was created with additional stochastic process analysis for detailed frequency and amplitude characteristics. Videogrammetry was used for the assessment of flow regimes, which were held in various types of fluidization apparatuses. Classic bubbling, jet-spouted and fast circulating fluidization processes were explored under the investigation. Videogrammetry is non-invasive flow regime recognition method, which enables detailed research of gas-particle fluidization phenomena. Until now, there were no comparative studies for three different types of fluidization processes with the use of one complex approach. Developed videogrammetric method consists of the flow structure visualization and dynamic image analysis. The analysed feature is the grey level of the image in time domain, and grey level signals were analysed with the use of autocorrelation function and power density function. The results are presented as images, plots and a flow map. Efficiency of the method was tested by comparison of real observed flow structures to the reconstructed flow structures and the recognition accuracy reached 92%.

  2. 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.

  3. 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.

  4. 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.

  5. Agglomeration-Free Distributor for Fluidized Beds

    NASA Technical Reports Server (NTRS)

    Ouyang, F.; Sinica, A.; Levenspiel, O.

    1986-01-01

    New gas distributor for fluidized beds prevents hot particles from reacting on it and forming hard crust. In reduction of iron ore in fluidized bed, ore particles do not sinter on distributor and perhaps clog it or otherwise interfere with gas flow. Distributor also relatively cool. In fluidized-bed production of silicon, inflowing silane does not decompose until within bed of hot silicon particles and deposits on them. Plates of spiral distributor arranged to direct incoming gas into spiral flow. Turbulence in flow reduces frequency of contact between fluidized-bed particles and distributor.

  6. Agglomeration-Free Distributor for Fluidized Beds

    NASA Technical Reports Server (NTRS)

    Ouyang, F.; Sinica, A.; Levenspiel, O.

    1986-01-01

    New gas distributor for fluidized beds prevents hot particles from reacting on it and forming hard crust. In reduction of iron ore in fluidized bed, ore particles do not sinter on distributor and perhaps clog it or otherwise interfere with gas flow. Distributor also relatively cool. In fluidized-bed production of silicon, inflowing silane does not decompose until within bed of hot silicon particles and deposits on them. Plates of spiral distributor arranged to direct incoming gas into spiral flow. Turbulence in flow reduces frequency of contact between fluidized-bed particles and distributor.

  7. Fluidization technologies: Aerodynamic principles and process engineering.

    PubMed

    Dixit, Rahul; Puthli, Shivanand

    2009-11-01

    The concept of fluidization has been adapted to different unit processes of pharmaceutical product development. Till date a lot of improvements have been made in the engineering design to achieve superior process performance. This review is focused on the fundamental principles of aerodynamics and hydrodynamics associated with the fluidization technologies. Fluid-bed coating, fluidized bed granulation, rotor processing, hot melt granulation, electrostatic coating, supercritical fluid based fluidized bed technology are highlighted. Developments in the design of processing equipments have been explicitly elucidated. This article also discusses processing problems from the operator's perspective along with latest developments in the application of these principles.

  8. 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.

  9. Pulsed atmospheric fluidized bed combustion

    SciTech Connect

    Not Available

    1992-10-01

    The design of the Pulsed Atmospheric Fluidized Bed Combustor (PAFBC) as described in the Quarterly Report for the period April--June, 1992 was reviewed and minor modifications were included. The most important change made was in the coal/limestone preparation and feed system. Instead of procuring pre-sized coal for testing of the PAFBC, it was decided that the installation of a milling system would permit greater flexibility in the testing with respect to size distributions and combustion characteristics in the pulse combustor and the fluid bed. Particle size separation for pulse combustor and fluid bed will be performed by an air classifier. The modified process flow diagram for the coal/limestone handling system is presented in Figure 1. The modified process flow diagrams of the fluidized bed/steam cycle and ash handling systems are presented in Figures 2 and 3, respectively.

  10. Fluidization mechanisms in slurry flow

    SciTech Connect

    Campbell, C. S.

    1989-01-01

    There are two mechanisms by which heavy settling particles may be suspended in a horizontal slurry flow: (1) by particle-particle interactions (e.g. Bagnold dispersive stresses) and (2) by particle-fluid interactions (e.g. entrainment of the particles by turbulent eddies.) The purpose of this investigation is to determine to what extent each fluidization mechanism is active and the effect of the fluidization mechanism on the global properties of the slurry. The technique employs the understanding that the particles entrained in the turbulence of the fluid will appear as an increased hydrostatic head across the channel. This may be directly measured and can be related to the fraction of the mass of particles that are supported by fluid-particle forces. (The rest must therefore be supported by particle-particle forces.) 17 refs., 26 figs.

  11. Fluidizing device for solid particulates

    DOEpatents

    Diebold, J.P.; Scahill, J.W.

    1984-06-27

    A flexible whip or a system of whips with novel attachments is suspended in a hopper and is caused to impact against fibrous and irregularly shaped particulates in the hopper to fluidize the particulates and facilitate the flow of the particulates through the hopper. The invention provides for the flow of particulates at a substantially constant mass flow rate and uses a minimum of energy.

  12. Pulsed atmospheric fluidized bed combustion

    SciTech Connect

    Not Available

    1992-05-01

    During this first quarter, a lab-scale water-cooled pulse combustor was designed, fabricated, and integrated with old pilot-scale PAFBC test systems. Characterization tests on this pulse combustor firing different kinds of fuel -- natural gas, pulverized coal and fine coal -- were conducted (without fluidized bed operation) for the purpose of finalizing PAFBC full-scale design. Steady-state tests were performed. Heat transfer performance and combustion efficiency of a coal-fired pulse combustor were evaluated.

  13. Fluidizing device for solid particulates

    DOEpatents

    Diebold, James P.; Scahill, John W.

    1986-01-01

    A flexible whip or a system of whips with novel attachments is suspended in a hopper and is caused to impact against fibrous and irregularly shaped particulates in the hopper to fluidize the particulates and facilitate the flow of the particulates through the hopper. The invention provides for the flow of particulates at a substantially constant mass flow rate and uses a minimum of energy.

  14. Vibrational Spectroscopy of Water at Liquid/Solid Interfaces: Crossing the Isoelectric Point of a Solid Surface

    NASA Astrophysics Data System (ADS)

    Yeganeh, M. S.; Dougal, S. M.; Pink, H. S.

    1999-08-01

    We have used IR-visible sum-frequency generation (SFG) spectroscopy to demonstrate that water dipoles at a liquid/solid interface flip by 180° when the pH of the aqueous solution crosses the isoelectric point of the surface (IEPS). We have also shown, for the first time, that the SFG signal intensity and thus the nonlinear polarizability of a water/solid interface depends strongly on the hydroxyl number density of the solid surface. A new methodology for the determination of the IEPS of a nonconductive, low-surface area material was introduced.

  15. Diameter dependence of the growth velocity of silicon nanowires synthesized via the vapor-liquid-solid mechanism

    NASA Astrophysics Data System (ADS)

    Schmidt, V.; Senz, S.; Gösele, U.

    2007-01-01

    We present a model for the radius dependence of the growth velocity of Si nanowires synthesized via the vapor-liquid-solid mechanism. By considering the interplay of the Si incorporation and crystallization rate at steady state conditions we show that the radius dependence of the growth velocity in general depends on the derivatives of the incorporation and crystallization velocity with respect to the supersaturation. Taking this into account, the apparently contradictory experimental observations regarding the radius dependence of the growth velocity can be reconciled and explained consistently.

  16. Improved liquid/solids handling module. Final report 2321:01, 1 September 1979-31 October 1980

    SciTech Connect

    West, L.K.

    1980-01-01

    A Mobile Liquid/Solids handling (L/S) unit was constructed that is the active element for a low cost Advanced Primary Geothermal Heat Exchanger (APEX), presently under development. The L/S system incorporates two alternating hydrocyclone-accumulator tank combinations and an injection pump. Sand particles are injected into the main flow and then separated and recirculated at capture efficiencies of greater than 99%. The system was tested at varying flowrates, solids concentrations, and particle sizes to determine an optimum operating point.

  17. "Liquid-liquid-solid"-type superoleophobic surfaces to pattern polymeric semiconductors towards high-quality organic field-effect transistors.

    PubMed

    Wu, Yuchen; Su, Bin; Jiang, Lei; Heeger, Alan J

    2013-12-03

    Precisely aligned organic-liquid-soluble semiconductor microwire arrays have been fabricated by "liquid-liquid-solid" type superoleophobic surfaces directed fluid drying. Aligned organic 1D micro-architectures can be built as high-quality organic field-effect transistors with high mobilities of >10 cm(2) ·V(-1) ·s(-1) and current on/off ratio of more than 10(6) . All these studies will boost the development of 1D microstructures of organic semiconductor materials for potential application in organic electronics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Engineering scale development of the Vapor-Liquid-Solid (VLS) process for the production of silicon carbide fibrils

    SciTech Connect

    Hollar, W.E. Jr.; Mills, W.H.

    1993-09-01

    Vapor-liquid-solid (VLS)SiC fibrils are used as reinforcement in ceramic matrix composites (CMC). A program has been completed for determining process scaleup parameters and to produce material for evaluation in a CMC. The scaleup is necessary to lower production cost and increase material availability. Scaleup parameters were evaluated in a reactor with a vertical dimension twice that of the LANL reactor. Results indicate that the scaleup will be possible. Feasibility of recycling process gas was demonstrated and the impact of postprocessing on yields determined.

  19. Modeling of fluidized bed silicon deposition process

    NASA Technical Reports Server (NTRS)

    Kim, K.; Hsu, G.; Lutwack, R.; PRATURI A. K.

    1977-01-01

    The model is intended for use as a means of improving fluidized bed reactor design and for the formulation of the research program in support of the contracts of Silicon Material Task for the development of the fluidized bed silicon deposition process. A computer program derived from the simple modeling is also described. Results of some sample calculations using the computer program are shown.

  20. The Mechanics of Localized Fluidization Burrowing

    NASA Astrophysics Data System (ADS)

    Winter, Amos

    2013-11-01

    This presentation will focus on the granular mechanics and critical timescales related to localized fluidization burrowing, a digging method inspired by the Atlantic razor clam (Ensis directus). The animal uses motions of its valves to locally fail and then fluidize surrounding soil to reduce burrowing energy and drag. The characteristic contraction time to achieve fluidization can be determined from substrate properties. The geometry of the fluidized zone is dictated by the coefficient of lateral earth pressure and friction angle of the soil. Calculations using full ranges for these parameters indicate that the fluidized zone is a local effect, occurring between 1-5 body radii away from the animal. The energy associated with motion through fluidized substrate - characterized by a depth-independent density and viscosity - scales linearly with depth. In contrast, moving through static soil requires energy that scales with depth squared. For engineers, localized fluidization offers a mechanically simple and purely kinematic method to dramatically reduce energy costs associated with digging. This concept is demonstrated with RoboClam, an E. directus-inspired robot. Using a genetic algorithm to find optimal digging kinematics, RoboClam has achieved localized fluidization burrowing performance comparable to that of the animal, with a linear energy-depth relationship, in both idealized granular glass beads and E. directus' native cohesive mudflat habitat.

  1. Fluidized-bed copper oxide process

    SciTech Connect

    Shah, P.P.; Takahashi, G.S.; Leshock, D.G.

    1991-10-14

    The fluidized-bed copper oxide process was developed to simultaneously remove sulfur dioxide and nitrogen oxide contaminants from the flue gas of coal-fired utility boilers. This dry and regenerable process uses a copper oxide sorbent in a fluidized-bed reactor. Contaminants are removed without generating waste material. (VC)

  2. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Archie Robertson

    2004-07-01

    Foster Wheeler Power Group, Inc. is working under US Department of Energy Contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. Under this contract a series of pilot plant tests are being conducted to ascertain PGM performance with a variety of fuels. The performance and economics of a PGM based plant designed for the co-production of hydrogen and electricity will also be determined. This report describes the work performed during the April-June 30, 2004 time period.

  3. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Archie Robertson

    2003-07-23

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the April 1--June 30, 2003 time period.

  4. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Archie Robertson

    2003-10-29

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the July 1--September 30, 2003 time period.

  5. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Unknown

    2003-01-30

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1--December 31, 2002 time period.

  6. Development of Pressurized Circulating Fluidized Bed Partial Gasification Module (PGM)

    SciTech Connect

    A. Robertson

    2003-12-31

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1 - December 31, 2003 time period.

  7. Development of Pressurized Circulating Fluidized Bed Partial Gasification Module (PGM)

    SciTech Connect

    A. Robertson

    2002-09-30

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the July 1-September 30, 2002 time period.

  8. 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.

  9. Hydrodynamics and energy consumption studies in a three-phase liquid circulating three-phase fluid bed contactor

    SciTech Connect

    Rusumdar, Ahmad J; Abuthalib, A.; Mohan, Vaka Murali; Srinivasa Kumar, C.; Sujatha, V.; Rajendra Prasad, P.

    2009-07-15

    The hydrodynamics and energy consumption have been studied in a cold flow, bubbling and turbulent, pressurized gas-liquid-solid three-phase fluidized bed (0.15 m ID x 1 m height) with concurrent gas-liquid up flow is proposed with the intention of increasing the gas hold up. The hydrodynamic behaviour is described and characterised by some specific gas and liquid velocities. Particles are easily fluidized and can be uniformly distributed over the whole height of the column. The effect of parameters like liquid flow rate, gas flow rate, particle loading, particle size, and solid density on gas hold up and effect of gas flow rate, solid density and particle size on solid hold up, energy consumption and minimum fluidization velocity has been studied. At the elevated pressures a superior method for better prediction of minimum fluidization velocity and terminal settling velocities has been adopted. The results have been interpreted with Bernoulli's theorem and Richardson-Zaki equation. Based on the assumption of the gas and liquid as a pretend fluid, a simplification has been made to predict the particle terminal settling velocities. The Richardson-Zaki parameter n' was compared with Renzo's results. A correlation has been proposed with the experimental results for the three-phase fluidization. (author)

  10. A flux induced crystal phase transition in the vapor-liquid-solid growth of indium-tin oxide nanowires.

    PubMed

    Meng, Gang; Yanagida, Takeshi; Yoshida, Hideto; Nagashima, Kazuki; Kanai, Masaki; Zhuge, Fuwei; He, Yong; Klamchuen, Annop; Rahong, Sakon; Fang, Xiaodong; Takeda, Seiji; Kawai, Tomoji

    2014-06-21

    Single crystalline metal oxide nanowires formed via a vapor-liquid-solid (VLS) route provide a platform not only for studying fundamental nanoscale properties but also for exploring novel device applications. Although the crystal phase variation of metal oxides, which exhibits a variety of physical properties, is an interesting feature compared with conventional semiconductors, it has been difficult to control the crystal phase of metal oxides during the VLS nanowire growth. Here we show that a material flux critically determines the crystal phase of indium-tin oxide nanowires grown via the VLS route, although thermodynamical parameters, such as temperature and pressure, were previously believed to determine the crystal phase. The crystal phases of indium-tin oxide nanowires varied from the rutile structures (SnO2), the metastable fluorite structures (InxSnyO3.5) and the bixbyite structures (Sn-doped In2O3) when only the material flux was varied within an order of magnitude. This trend can be interpreted in terms of the material flux dependence of crystal phases (rutile SnO2 and bixbyite In2O3) on the critical nucleation at the liquid-solid (LS) interface. Thus, precisely controlling the material flux, which has been underestimated for VLS nanowire growths, allows us to design the crystal phase and properties in the VLS nanowire growth of multicomponent metal oxides.

  11. Impact of preferential indium nucleation on electrical conductivity of vapor-liquid-solid grown indium-tin oxide nanowires.

    PubMed

    Meng, Gang; Yanagida, Takeshi; Nagashima, Kazuki; Yoshida, Hideto; Kanai, Masaki; Klamchuen, Annop; Zhuge, Fuwei; He, Yong; Rahong, Sakon; Fang, Xiaodong; Takeda, Seiji; Kawai, Tomoji

    2013-05-08

    Highly conductive and transparent indium-tin oxide (ITO) single-crystalline nanowires, formed by the vapor-liquid-solid (VLS) method, hold great promise for various nanoscale device applications. However, increasing an electrical conductivity of VLS grown ITO nanowires is still a challenging issue due to the intrinsic difficulty in controlling complex material transports of the VLS process. Here, we demonstrate a crucial role of preferential indium nucleation on the electrical conductivity of VLS grown ITO nanowires using gold catalysts. In spite of the fact that the vapor pressure of tin is lower than that of indium, we found that the indium concentration within the nanowires was always higher than the nominal composition. The VLS growth of ITO through gold catalysts significantly differs from ITO film formations due to the emergence of preferential indium nucleation only at a liquid-solid interface. Furthermore, we demonstrate that the averaged resistivity of ITO nanowires can be decreased down to 2.1 × 10(-4) Ω cm, which is the lowest compared with values previously reported, via intentionally increasing the tin concentration within the nanowires.

  12. Influence of temperature, time, liquid/solid ratio and sulfuric acid concentration on the hydrolysis of palm empty fruit bunches.

    PubMed

    Ferrer, Ana; Requejo, Ana; Rodríguez, Alejandro; Jiménez, Luis

    2013-02-01

    The influence of temperature (150-190 °C), time (0-20 min), liquid/solid ratio (6-8) and sulfuric acid concentration (0.1-0.5%), on the hydrolysis of palm empty fruit bunches (EFBs) was studied and the liquid and solid fractions were analyzed. Polynomial models were found to reproduce the experimental results with errors less than 15% in most of the cases (except for xylose concentration). Operating conditions of 190 °C for 15 min at a liquid/solid ratio of 6 and a sulfuric acid concentration of 0.1% resulted in the production of 3.12, 4.0, 2.35 and 2.28 g/L of glucose, xylose, arabinose and acetic acid, respectively, starting with 1000 g of EFBs. The yield was 67.96%. Soda-anthraquinone, ethanol and ethanolamine pulping of the solid fraction provided pulps with brightness values (63.24%, 28.78%, 48.76%), but with poor resistance properties (6.57-8.54 Nm/g for tensile index, 0.38-0.44 k N/g for burst index and 0.96-1.02 mN m2/g for tear index). Therefore it is advisable to use the pulps for speciality papers or for bioethanol-production. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. A new method for the measurement of solids holdup in gas-liquid-solid three-phase systems

    SciTech Connect

    Wenge, F.; Chisti, Y.; Moo-Young, M.

    1995-03-01

    Gas-liquid-solid multiphase systems are commonly encountered in the chemical process industry, in bio-processing, and in environmental pollution abatement devices. A method for the measurement of gas and solids holdups in gas-liquid-solid multiphase devices is developed and tested. The method depends on measurements of hydrostatic pressures in the three-phase dispersion followed by interruption of gas flow, complete gas disengagement, and a second pressure measurement in the resulting two-phase solid-liquid slurry, over a short period of time (< 30 s). The proposed method is compared with results obtained with physical sampling of the multiphase flow in vertical up- and down-flow in a large airlift reactor (0.243 m diameter, 7.825 m overall height, 2.44 riser-to-downcomer cross-sectional area ratio). Applicability of the technique to slurries of glass beads in tap water is demonstrated for various sizes and concentrations of beads over a range of gas flow rates (0.070--0.150 {times} 10{sup {minus}3} m bead diameter, 2,500 kg/m{sup 3} solids density, 0.02--0.17 m/s superficial gas velocity).

  14. Liquid-solid phase transition of Ge-Sb-Te alloy observed by in-situ transmission electron microscopy.

    PubMed

    Berlin, Katja; Trampert, Achim

    2016-11-05

    Melting and crystallization dynamics of the multi-component Ge-Sb-Te alloy have been investigated by in-situ transmission electron microscopy (TEM). Starting point of the phase transition study is an ordered hexagonal Ge1Sb2Te4 thin film on Si(111) where the crystal structure and the chemical composition are verified by scanning TEM and electron energy-loss spectroscopy, respectively. The in-situ observation of the liquid phase at 600°C including the liquid-solid and liquid-vacuum interfaces and their movements was made possible due to an encapsulation of the TEM sample. The solid-liquid interface during melting displays a broad and diffuse transition zone characterized by a vacancy induced disordered state. Although the velocities of interface movements are measured to be in the nanometer per second scale, both, for crystallization and solidification, the underlying dynamic processes are considerably different. Melting reveals linear dependence on time, whereas crystallization exhibits a non-linear time-dependency featuring a superimposed start-stop motion. Our results may provide valuable insight into the atomic mechanisms at interfaces during the liquid-solid phase transition of Ge-Sb-Te alloys.

  15. Experimental Data on Liquid-Solid Phase Transition in Tin Using Pulsed Magnetic Loading on the Saturn Accelerator

    NASA Astrophysics Data System (ADS)

    Davis, Jean-Paul; Hayes, Dennis B.; Asay, James R.; Flores, Paul A.; Watts, Phillip W.; Reisman, David B.

    2001-10-01

    Isentropic ramp-wave loading of materials is a novel method to study the kinetics of phase transitions, particularly in regimes that are overdriven by shock-loading techniques or that cannot be accessed using shock-loading techniques. In our experiments, the Sandia Saturn accelerator produces magnetically driven planar ramp waves of 200-300 ns rise time in aluminum, which then propagate into a material sample. To study the kinetics of the liquid-solid transition in tin under dynamic loading, molten tin initially at 600-800 K is isentropically loaded up to 300 kbar, driving it across the liquid-solid phase boundary. Experiments currently under way to obtain VISAR measurements at a lithium flouride window interface should show evidence of nonequilibrium freezing in tin if the characteristic transition time is in the range of 10-400 ns. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

  16. Finite difference predictions of P-SV wave propagation inside submerged solids. I. Liquid-solid interface conditions.

    PubMed

    Dahake, G; Gracewski, S M

    1997-10-01

    A finite difference scheme has been developed to analyze internal strains in submerged elastic solids of irregular geometry subjected to ultrasonic wave sources that simulate a clinical lithotripter. In part I of this paper, the finite difference formulation that accounts for arbitrary liquid-solid interfaces is presented and sample numerical results are discussed. Two different methods for discretizing the liquid-solid interface conditions are developed. The first treats the interface conditions explicitly. The second integrates the heterogeneous wave equations across the interface using the divergence theorem. Both schemes account for varying grid sizes and give similar results for a test problem consisting of a radially diverging source incident on the rectangular solid. The time sequence obtained numerically for strain at the center of a rectangular solid matches well with the experimental results [S. M. Gracewski et al., J. Acoust. Soc. Am. 94, 652-661 (1993)] in terms of the arrival times and the relative amplitudes of the peaks. In addition, strain contours are plotted to visualize the propagation of P (longitudinal) and S (shear vertical) waves inside a circular solid. The reflection from the concave back surface of the circular solid has a focusing effect with the subsequent formation of focal zones, known as caustics, where peak strains occur. In part II of this paper, the finite difference scheme is used to study the effects of geometry changes on the internal stresses and caustics predicted in model stones subjected to lithotripter pulses.

  17. Born-Haber cycle for monolayer self-assembly at the liquid-solid interface: assessing the enthalpic driving force.

    PubMed

    Song, Wentao; Martsinovich, Natalia; Heckl, Wolfgang M; Lackinger, Markus

    2013-10-02

    The driving force for self-assembly is the associated gain in free energy with decisive contributions from both enthalpy and entropy differences between final and initial state. For monolayer self-assembly at the liquid-solid interface, solute molecules are initially dissolved in the liquid phase and then become incorporated into an adsorbed monolayer. In this work, we present an adapted Born-Haber cycle for obtaining precise enthalpy values for self-assembly at the liquid-solid interface, a key ingredient for a profound thermodynamic understanding of this process. By choosing terephthalic acid as a model system, it is demonstrated that all required enthalpy differences between well-defined reference states can be independently and consistently assessed by both experimental and theoretical methods, giving in the end a reliable value of the overall enthalpy gain for self-assembly of interfacial monolayers. A quantitative comparison of enthalpy gain and entropy cost reveals essential contributions from solvation and dewetting, which lower the entropic cost and render monolayer self-assembly a thermodynamically favored process.

  18. Time-resolved analytical methods for liquid/solid interfaces. Progress report, November 1, 1993--October 31, 1994

    SciTech Connect

    Harris, J.M.

    1994-10-31

    A number of chemical phenomena that occur at the boundaries between insulating solids and liquids (adsorption, partition, monolayer self-assembly, catalysis, and chemical reactions) are important to energy-related analytical chemistry. These phenomena are central to the development and understanding of chromatographic methods, solid-phase extraction techniques, immobilized analytical reagents, and optical sensors. The goal of this program, therefore, is to develop surface-sensitive spectroscopies by which chemical kinetics at liquid/solid interfaces can be observed on time-scales from nanoseconds to seconds. In the second year of this program, the authors have used temperature-jump relaxation measurements to monitor adsorption/desorption kinetics at liquid/solid interfaces using Joule heating to compare the adsorption of ions from solution onto C1- and C4-derivatized silica surfaces. They completed a study of rate of migration of covalently-attached ligands on silica surfaces; from the temperature-dependence of the migration, the large energy barrier to migration was estimated. Surface heterogeneity of adsorption sites on silica was characterized by time-resolve fluorescence, and the chemical origins investigated by Si{sup 29} NMR spectroscopy. Surface-enhance Raman and fluorescence spectroscopies were modified to study adsorption and binding to silica surfaces. Molecular dynamics simulations were started to help better understand kinetic barriers to adsorption; ESR probe measurements were launched to measure and compare the chain mobility of silica-attached alkyl ligands.

  19. Attrition resistant fluidizable reforming catalyst

    DOEpatents

    Parent, Yves O.; Magrini, Kim; Landin, Steven M.; Ritland, Marcus A.

    2011-03-29

    A method of preparing a steam reforming catalyst characterized by improved resistance to attrition loss when used for cracking, reforming, water gas shift and gasification reactions on feedstock in a fluidized bed reactor, comprising: fabricating the ceramic support particle, coating a ceramic support by adding an aqueous solution of a precursor salt of a metal selected from the group consisting of Ni, Pt, Pd, Ru, Rh, Cr, Co, Mn, Mg, K, La and Fe and mixtures thereof to the ceramic support and calcining the coated ceramic in air to convert the metal salts to metal oxides.

  20. Scaling of pressurized fluidized beds

    SciTech Connect

    Guralnik, S.; Glicksman, L.R.

    1994-10-01

    The project has two primary objectives. The first is to verify a set of hydrodynamic scaling relationships for commercial pressurized fluidized bed combustors (PFBC). The second objective is to investigate solids mixing in pressurized bubbling fluidized beds. American Electric Power`s (AEP) Tidd combined-cycle demonstration plant will provide time-varying pressure drop data to serve as the basis for the scaling verification. The verification will involve demonstrating that a properly scaled cold model and the Tidd PFBC exhibit hydrodynamically similar behavior. An important issue in PFBC design is the spacing of fuel feed ports. The feed spacing is dictated by the fuel distribution and the mixing characteristics within the bed. After completing the scaling verification, the cold model will be used to study the characteristics of PFBCs. A thermal tracer technique will be utilized to study mixing both near the fuel feed region and in the far field. The results allow the coal feed and distributor to be designed for optimal heating.

  1. Fluidization mechanisms in slurry flows

    NASA Astrophysics Data System (ADS)

    Campbell, Charles S.

    1988-08-01

    A transducer is developed to measure particle pressures independently from fluid pressure. Initially it was thought that particle pressure was the only path by which the fluidization mechanism could be determined. The particle pressure transducer has been described in previous reports. A secondary project was developed to test these transducers and use them to measure the particle pressures generated against the side walls of gas-fluidized beds. This was a way to gain experience with the particle pressure transducer while awaiting the delivery of the pump and other components for the slurry pipe loop. Earlier this year, there was great difficulty in gaining repeatable results from the experiments. The culprit turned out to be static charge buildup in the granular mass. Hence, steam was injected into the air stream to help dissipate the charge buildup. This produced a further source of error that was eventually traced to the fiberoptic displacement transducer inside the probe. It developed that the transducer was sensitive to humidity. It has been suggested that this reaction might be a byproduct of the absorption of water onto the sensing surface changes its optical properties and hence its output signal.

  2. Hydrodynamics, mixing, gas-liquid mass transfer, and biological applications of a three-phase fluidized bed of low density particles

    SciTech Connect

    Tang, W.T.

    1988-01-01

    Experiments were conducted to study the axial holdup distributions, liquid axial mixing and gas-liquid mass transfer behavior in a three-phase fluidized bed of low density particles. Axial phase holdups were determined using an electrical conductivity method coupled with pressure profile measurements. Gas holdup was found to be axially uniform. Axial solids holdup distributions changed only slightly with increasing gas velocity but varied significantly when a change in bubble flow regime was encountered due to changes in liquid velocity. A mechanistic model based on solids entrainment and deentrainment effects by bubbles was proposed and validated experimentally. The extent of liquid axial mixing in both a liquid-solid and a three-phase fluidized bed of low density particles is significantly smaller than that in a bed of heavy particles. Volumetric gas-liquid mass transfer coefficients in the present systems decreases with increasing solids concentration. For the low density particles studied, particles with a higher terminal velocity promoted greater extent of bubble coalescence which reduced gas holdup, and thus the rate of gas-liquid mass transfer. In addition, the dynamic responses of phenol biodegradation in a draft tube three-phase fluidized bed biofilm reactor subjected to a step increase in phenol inlet concentrations were investigated. A comprehensive mathematical model, which considered time delay phenomenon of microbial growth subjected to a nutrient shift up, phenol adsorption/desorption by carbon particles, and biofilm growth, was proposed and validated experimentally.

  3. 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.

  4. Investigation of fluidized-bed biological denitrification

    SciTech Connect

    Acox, T.A.

    1982-12-16

    The performance of the fluidized-bed bioreactor was modelled for denitrification using a multiple linear regression. Reasonable accuracy was obtained; however, this type of analysis did not take into account the hydraulic characteristics of the fluidized-bed. The Mulcahy and LaMotta computer program previously used to model a fluidized-bed bioreactor cannot be used in this case due to the Michaelis-Menton constant k determined in this study, which was one to two orders of magnitude lower. With some additional bioreactor study and computer program modification, this may prove to be of some benefit.

  5. 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.

  6. 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.

  7. Spatiotemporal dynamics of a shallow fluidized bed.

    SciTech Connect

    Aranson, I. S.; Tsimring, L. S.; Clark, D. K.

    2000-12-05

    An experimental and theoretical study of the dynamics of an air-fluidized thin granular layer is presented. Near the threshold of instability, the system exhibits critical behavior with remarkably long transient dynamics. Above the threshold of fluidization the system undergoes a Hopf bifurcation as the layer starts to oscillate at a certain frequency due to a feedback between the layer dilation and the airflow rate. Based on our experimental data, we formulate a the simple dynamical model which describes the transition in a shallow fluidized bed.

  8. Correlating throughput and backmixing in fluidized beds

    SciTech Connect

    Papa, G. ); Zenz, F.A. )

    1995-01-01

    The homogeneity of a fluidized bed, usually regarded kinetically as a stirred tank reactor, can be altered to approach plug flow by properly designed internals that limit dense-phase mixing action. These internals can achieve desired temperature or concentration gradients along the bed height. A new correlation has been developed that models throughput and backmixing for gas-liquid and gas-solid systems. Maximum performance is in the neighborhood of 75% to 80% of the ultimate throughput capacity. The paper discusses backmixing mechanisms in fluidized beds; approaches to plug flow in fluidized beds; limiting capacities of structured internals; and the optimum design for structured grid internals.

  9. Shadowing and mask opening effects during selective-area vapor-liquid-solid growth of InP nanowires by metalorganic molecular beam epitaxy.

    PubMed

    Kelrich, A; Calahorra, Y; Greenberg, Y; Gavrilov, A; Cohen, S; Ritter, D

    2013-11-29

    Indium phosphide nanowires were grown by metalorganic molecular beam epitaxy using the selective-area vapor-liquid-solid method. We show experimentally and theoretically that the size of the annular opening around the nanowire has a major impact on nanowire growth rate. In addition, we observed a considerable reduction of the growth rate in dense two-dimensional arrays, in agreement with a calculation of the shadowing of the scattered precursors. Due to the impact of these effects on growth, they should be considered during selective-area vapor-liquid-solid nanowire epitaxy.

  10. Demonstration of an advanced circulation fludized bed coal combustor phase 1: Cold model study. Final report

    SciTech Connect

    Govind, R.

    1993-03-20

    It was found that there was a strong dependence of the density profile on the secondary air injection location and that there was a pronounced solid separation from the conveying gas, due to the swirl motion. Furthermore, the swirl motion generated strong internal circulation patterns and higher slip velocities than in the case of nonswirl motion as in an ordinary circulating fluidized bed. Radial solids flux profiles were measured at different axial locations. The general radial profile in a swirling circulating fluidized bed indicated an increased downward flow of solids near the bed walls, and strong variations in radial profiles along the axial height. For swirl numbers less than 0.9, which is typical for swirling circulating fluidized beds, there is no significant increase in erosion due to swirl motion inside the bed. Pending further investigation of swirl motion with combustion, at least from our cold model studies, no disadvantages due to the introduction of swirl motion were discovered.

  11. Design and operation of a coal-washery sludge fired 75 t/h steam fluidized bed combustion boiler

    SciTech Connect

    Jiang, X.; Chi, Y.; Yan, J.

    1999-07-01

    Based upon the coal-washery sludge fluidized bed agglomerating combustion technology developed by Zhejiang University and the design and operation experience accumulated from the 35 t/h stream fluidized bed boilers, a coal-washery sludge fired 75 t/h steam circulating fluidized bed boiler (12 MWe) for cogeneration application was designed. The design features of the boiler can be summarized as follows: (1) Combination of solid particle impact separator (in furnace circulation) and moderate temperature ({approximately}500 C) uniflow cyclone; (2) Low solid circulation rate; (3) Loop-seal for solid particle recirculation; (4) Air duct oil burner for boiler start-up; and (5) Coal-Washery sludge firing or co-firing of coal-washery sludge and coal. The boiler is installed at Dongtan Coal Mine Cogeneration Plant in Shandong Province of China. The daily disposal capacity of coal-washery sludge is over 300 tons. The first trial operation of the boiler was on Dec. 18, 1997. The cogeneration plant has been in commercial operation since May 1998. This boiler is the largest capacity boiler to dispose of coal-washery sludge in China. The successful operation of this boiler has sped up the commercialization process of the coal-washery sludge fluidized bed combustion technology.

  12. A cold model experimental study on the flow characteristics of bed material in a fluidized bed bottom ash cooler in a CFB boiler

    NASA Astrophysics Data System (ADS)

    Lu, Xiaofeng; Li, Yourong

    2000-12-01

    A cold model experimental study on the flowing characteristics of bed material between a fluidized bed ash cooler and a furnace of CFB boiler were discussed in this paper. The research results showed that flowing status of the bed material in a bubbling bed, which was run with a circulating fluidized bed together in parallel operation, was influenced by the pressure difference between the CFB and the bubbling bed, the switch status of unlocking air, and the structure of the exit of the bubbling bed. There was a circulating flow of bed material between CFB and bubbling bed.

  13. Hydrodynamic model of advanced pressurized fluidized bed combustion

    SciTech Connect

    Horio, Masayuki; Lei, H.W.

    1997-12-31

    A hydrodynamic model was developed for the advanced pressurized fluidized bed combustion (A-PFBC) process. The particular system investigated here is composed of a pressurized circulating fluidized bed (PCFB) for coal gasification/desulfurization and a PCFB for combustion with the gas-solid counter-current flow through the two PCFBs. One of the most important parameters may be the material seal height (MSH) in the downcomer connecting the gasifier/desulfurizer and the combustor, which is thought to strongly influence the safe and stable operation of the process. In this mode, MSH was determined according to the pressure balance between the gasifier/desulfurizer and the combustor. The solid flux in the lower dense region of the two PCFBs was estimated by considering the clustering suspension and core-annulus flow. The mean cluster size and voidage in the cluster phase were predicted by the cluster size model of Horio-Ito (1996). Solid flux of the gasifier and combustor was calculated based on mass balances of limestone, char and ash in the system. Based on this model, the whole pressure profile loop in the system was predicted, and the effects of operating conditions on MSH between the gasifier and the combustor were investigated. The feasibility of the A-PCFB system with PCFBs both for the gasifier/desulfurizer and for the combustor was successfully confirmed.

  14. Study of liquid-solid catalytic reaction of epichlorohydrin with sodium butyrate in the presence of tetrabutylammonium bromide

    NASA Astrophysics Data System (ADS)

    Huang, Qiang; Meng, Qingyi; Ban, Chunlan; Zhang, Rui; Gao, Yingyu

    2016-08-01

    The liquid-solid catalytic reaction of epichlorohydrin and sodium butyrate with tetrabutylammonium bromide as a phase transfer catalyst was studied in this paper. The shrinking core model was applied. The analysis of the reaction based on the kinetic model showed a reaction-controlled regime at temperatures varying from 90 to 100°C. The exterior diffusivity was removed between 300 and 400 rpm. The internal diffusivity was removed when the particle size was 2 × 10-4 m. Reaction rate constants were calculated at different temperatures. The correlation was obtained when the proposed kinetic model was applied to all the experimental data for predictive evaluations and the activation energy was 37.01 kJ mol-1.

  15. Pure wurtzite GaP nanowires grown on zincblende GaP substrates by selective area vapor liquid solid epitaxy.

    PubMed

    Halder, Nripendra Narayan; Kelrich, Alexander; Cohen, Shimon; Ritter, Dan

    2017-09-08

    We report on the growth of single phase wurtzite (WZ) GaP nanowires (NWs) on GaP (111) B substrates by metal organic molecular beam epitaxy following the selective area vapor-liquid-solid (SA-VLS) approach. During the SA-VLS process, precursors are supplied directly to the NW sidewalls, and the short diffusion length of gallium (or its precursors) does not significantly limit axial growth. Transmission electron microscopy (TEM) images reveal that no stacking faults are present along a 600 nm long NW. The lattice constants of the pure WZ GaP obtained from the TEM images agree with values determined previously by x-ray diffraction from non-pure NW ensembles. © 2017 IOP Publishing Ltd.

  16. III-Vs at Scale: A PV Manufacturing Cost Analysis of the Thin Film Vapor-Liquid-Solid Growth Mode

    SciTech Connect

    Zheng, Maxwell; Horowitz, Kelsey; Woodhouse, Michael; Battaglia, Corsin; Kapadia, Rehan; Javey, Ali

    2016-06-01

    The authors present a manufacturing cost analysis for producing thin-film indium phosphide modules by combining a novel thin-film vapor-liquid-solid (TF-VLS) growth process with a standard monolithic module platform. The example cell structure is ITO/n-TiO2/p-InP/Mo. For a benchmark scenario of 12% efficient modules, the module cost is estimated to be $0.66/W(DC) and the module cost is calculated to be around $0.36/W(DC) at a long-term potential efficiency of 24%. The manufacturing cost for the TF-VLS growth portion is estimated to be ~$23/m2, a significant reduction compared with traditional metalorganic chemical vapor deposition. The analysis here suggests the TF-VLS growth mode could enable lower-cost, high-efficiency III-V photovoltaics compared with manufacturing methods used today and open up possibilities for other optoelectronic applications as well.

  17. Experimental correlation of gas-liquid-solid mass transfer coefficient in a stirred tank using response surface methodology

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Duan, Xili; Gao, Zhengming

    2017-10-01

    In this paper, the three-phase (gas-liquid-solid) system in a stirred tank is experimentally studied. The response surface methodology (RSM) is used to analyze the three phase mass transfer coefficient under different conditions, i.e., rotation speeds (8, 10, and 12 s-1), volumetric solid content fractions (0, 6 and 12%), gas flow rates (6, 8, and 10 m3 h-1) and temperatures (40, 54, and 68 °C). With the RSM, it was found that all of these four operational parameters are significant in affecting the mass transfer coefficient, with the rotation speed being the most significant one. A new correlation is developed with a quadratic term for solid content fraction, indicating that there is a minimum value of mass transfer coefficient at a certain solid content fraction. Compared with traditional experimental design and correlation methods, the RSM in this study reduces experiment time and provides a better correlation to predict the mass transfer coefficient.

  18. Transition region width of nanowire hetero- and pn-junctions grown using vapor-liquid-solid processes

    NASA Astrophysics Data System (ADS)

    Li, Na; Tan, Teh Y.; Gösele, U.

    2008-03-01

    The transition region width of nanowire heterojunctions and pn-junctions grown using vapor-liquid-solid (VLS) processes has been modeled. With two constituents or dopants I and II, the achievable width or abruptness of the junctions is attributed to the residual I atom/molecule stored in the liquid droplet at the onset of introducing II to grow the junction, and the stored I atom/molecule consumption into the subsequently grown crystal layers. The model yields satisfactory quantitative fits to a set of available Si-Ge junction data. Moreover, the model provides a satisfactory explanation to the relative junction width or abruptness differences between elemental and compound semiconductor junction cases, as well as a guideline for achieving the most desirable pn-junction widths.

  19. Structural and electronic properties of InN nanowire network grown by vapor-liquid-solid method

    SciTech Connect

    Barick, B. K. E-mail: subho-dh@yahoo.co.in; Dhar, S. E-mail: subho-dh@yahoo.co.in; Rodríguez-Fernández, Carlos; Cantarero, Andres

    2015-05-15

    Growth of InN nanowires have been carried out on quartz substrates at different temperatures by vapor-liquid-solid (VLS) technique using different thicknesses of Au catalyst layer. It has been found that a narrow window of Au layer thickness and growth temperature leads to multi-nucleation, in which each site acts as the origin of several nanowires. In this multi-nucleation regime, several tens of micrometer long wires with diameter as small as 20 nm are found to grow along [112{sup -}0] direction (a-plane) to form a dense network. Structural and electronic properties of these wires are studied. As grown nanowires show degenerate n-type behavior. Furthermore, x-ray photoemission study reveals an accumulation of electrons on the surface of these nanowires. Interestingly, the wire network shows persistence of photoconductivity for several hours after switching off the photoexcitation.

  20. Predicting the growth of S i3N4 nanowires by phase-equilibrium-dominated vapor-liquid-solid mechanism

    NASA Astrophysics Data System (ADS)

    Zhang, Yongliang; Cai, Jing; Yang, Lijun; Wu, Qiang; Wang, Xizhang; Hu, Zheng

    2017-09-01

    Nanomaterial synthesis is experiencing a profound evolution from empirical science ("cook-and-look") to prediction and design, which depends on the deep insight into the growth mechanism. Herein, we report a generalized prediction of the growth of S i3N4 nanowires by nitriding F e28S i72 alloy particles across different phase regions based on our finding of the phase-equilibrium-dominated vapor-liquid-solid (PED-VLS) mechanism. All the predictions about the growth of S i3N4 nanowires, and the associated evolutions of lattice parameters and geometries of the coexisting Fe -Si alloy phases, are experimentally confirmed quantitatively. This progress corroborates the general validity of the PED-VLS mechanism, which could be applied to the design and controllable synthesis of various one-dimensional nanomaterials.

  1. Two-dimensional self-assembly of dendritic amphiphilic molecule with ferroncenyl subsitutuents at the liquid/solid interface.

    PubMed

    Miao, Xinrui; Cheng, Zhiyu; Xu, Li; Ren, Biye; Deng, Wenli

    2013-02-01

    Two-dimensional self-assembly of dendritic amphiphilic molecule with ferroncenyl subsitutuents (2,3,4-tri-(11-ferroncenyl)undecyloxybenzoic acid, Fc3COOH) on highly oriented pyrolytic graphite surface was investigated by scanning tunneling microscopy at the liquid/solid interface. Fc3COOH molecule formed an ordered molecular nanostructure--an alternating big/small bright dots pattern on the graphite surface extended to several hundred nanometers. On the basis of the simulation and combined with our STM results, it is concluded that the molecular adsorption conformation has an appreciable effect on the interactions of molecule-molecule and molecule-substrate. The pi-pi interactions between ferrocene groups together with the van der Waals interactions between alkyl chains direct the stacking behavior of Fc3COOH molecules. Due to the steric constraints, no hydrogen bonding between the carboxyl groups was formed during the self-assembly.

  2. Dispersed bubble reactor for enhanced gas-liquid-solids contact and mass transfer

    DOEpatents

    Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang; Bonsu, Alexander

    2016-01-26

    An apparatus to promote gas-liquid contact and facilitate enhanced mass transfer. The dispersed bubble reactor (DBR) operates in the dispersed bubble flow regime to selectively absorb gas phase constituents into the liquid phase. The dispersion is achieved by shearing the large inlet gas bubbles into fine bubbles with circulating liquid and additional pumped liquid solvent when necessary. The DBR is capable of handling precipitates that may form during absorption or fine catalysts that may be necessary to promote liquid phase reactions. The DBR can be configured with multistage counter current flow sections by inserting concentric cylindrical sections into the riser to facilitate annular flow. While the DBR can absorb CO.sub.2 in liquid solvents that may lead to precipitates at high loadings, it is equally capable of handling many different types of chemical processes involving solids (precipitates/catalysts) along with gas and liquid phases.

  3. Microcalorimetry Study of the Adsorption of Asphaltenes and Asphaltene Model Compounds at the Liquid-Solid Surface.

    PubMed

    Pradilla, Diego; Subramanian, Sreedhar; Simon, Sébastien; Sjöblom, Johan; Beurroies, Isabelle; Denoyel, Renaud

    2016-07-26

    The adsorption of an acidic polyaromatic asphaltene model compound (C5PeC11) and indigenous C6-asphaltenes onto the liquid-solid surface is studied. Model compound C5PeC11 exhibits a similar type of adsorption with a plateau adsorbed amount as C6-asphaltenes onto three surfaces (silica, calcite, and stainless steel). Model compound BisAC11, with aliphatic end groups and no acidic functionality, does not adsorb at the liquid-silica surface, indicating the importance of polar interactions on adsorption. The values of the adsorption enthalpy characterized by the ΔHz parameter (the enthalpy at zero coverage) indicate that the type of adsorption and the driving force depend on the surface, a key feature when discussing asphaltene deposition. The adsorption of C5PeC11 onto silica is shown to be driven primarily by H bonding (ΔHz = -34.9 kJ/mol), unlike adsorption onto calcite where polar van der Waals and acidic/basic interactions are thought to be predominant (ΔHz = -23.5 kJ/mol). Interactions between C5PeC11 and stainless steel are found to be weak (ΔHz = -7.7 kJ/mol). Comparing C6-asphaltenes and their esterified counterpart shows that adsorption at the liquid-solid surface is not influenced by the formation of H bonds. This was evidenced by the similar adsorbed amounts obtained. Finally, C5PeC11 captures, to a certain extent, the adsorption interactions of asphaltenes present at the calcite-oil and stainless steel-oil surfaces.

  4. 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.

  5. 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...

  6. 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.

  7. Drying of solids in fluidized beds

    SciTech Connect

    Kannan, C.S.; Thomas, P.P.; Varma, Y.B.G.

    1995-09-01

    Fluidized bed drying is advantageously adopted in industrial practice for drying of granular solids such as grains, fertilizers, chemicals, and minerals either for long shelf life or to facilitate further processing or handling. Solids are dried in batch and in continuous fluidized beds corresponding to cross-flow and countercurrent flow of phases covering a wide range in drying conditions. Materials that essentially dry with constant drying rate and then give a falling drying rate approximately linear with respect to solids moisture content (sand) as well as those with an extensive falling rate period with the subsequent falling rate being a curve with respect to the moisture content (mustard, ragi, poppy seeds) are chosen for the study. The performance of the continuous fluidized bed driers is compared with that of batch fluidized bed driers; the performance is predicted using batch kinetics, the residence time distribution of solids, and the contact efficiency between the phases.

  8. 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.

  9. Fluidized bed for production of polycrystalline silicon

    SciTech Connect

    Flagella, R.N.

    1992-08-18

    This patent describes a method for removing silicon powder particles from a reactor that produces polycrystalline silicon by the pyrolysis of a silane containing gas in a fluidized bed reaction zone of silicon seed particles. It comprises introducing the silane containing gas stream into the reaction zone of fluidized silicon seed particles; heterogeneously decomposing the silane containing gas under conditions; collecting the silicon product particles from the collection zone; and removing silicon powder particles from the reactor.

  10. Chaos suppression in gas-solid fluidization.

    PubMed

    Pence, Deborah V.; Beasley, Donald E.

    1998-06-01

    Fluidization in granular materials occurs primarily as a result of a dynamic balance between gravitational forces and forces resulting from the flow of a fluid through a bed of discrete particles. For systems where the fluidizing medium and the particles have significantly different densities, density wave instabilities create local pockets of very high void fraction termed bubbles. The fluidization regime is termed the bubbling regime. Such a system is appropriately termed a self-excited nonlinear system. The present study examines chaos suppression resulting from an opposing oscillatory flow in gas-solid fluidization. Time series data representing local, instantaneous pressure were acquired at the surface of a horizontal cylinder submerged in a bubbling fluidized bed. The particles had a weight mean diameter of 345 &mgr;m and a narrow size distribution. The state of fluidization corresponded to the bubbling regime and total air flow rates employed in the present study ranged from 10% to 40% greater than that required for minimum fluidization. The behavior of time-varying local pressure in fluidized beds in the absence of a secondary flow is consistent with deterministic chaos. Kolmogorov entropy estimates from local, instantaneous pressure suggest that the degree of chaotic behavior can be substantially suppressed by the presence of an opposing, oscillatory secondary flow. Pressure signals clearly show a "phase-locking" phenomenon coincident with the imposed frequency. In the present study, the greatest degree of suppression occurred for operating conditions with low primary and secondary flow rates, and a secondary flow oscillation frequency of 15 Hz. (c) 1998 American Institute of Physics.

  11. Solar energy assisted fluidized bed fruit drying

    NASA Astrophysics Data System (ADS)

    Kilkis, B.

    The possibility of using the fluidized-bed principle for solar drying of fruits economically and simply is explored. With the aid of computerized design methods, an optimized fluidized bed/packed bed combination was achieved, that in addition functions as a solar air heater. Based on this configuration, a novel aparatus was designed in Turkey for drying Turkish grapes. Comparisons with comparable systems are made.

  12. Fluidized-bed development at JPL

    NASA Technical Reports Server (NTRS)

    Hsu, G.

    1986-01-01

    Silicon deposition on silicon seed particles by silane pyrolysis in a fluidized bed reactor (FBR) was investigated as a low cost, high throughput method to produce high purity polysilicon for solar cell applications. The emphasis of the research is fundamental understanding of fluidized bed silicon deposition. The mechanisms involved were modeled as a six-path process: heterogeneous deposition; homogeneous decomposition; coalescence; coagulation; scavenging; and chemical vapor deposition growth on fines.

  13. Localized fluidization in a granular medium.

    PubMed

    Philippe, P; Badiane, M

    2013-04-01

    We present here experimental results on the progressive development of a fluidized zone in a bed of grains, immersed in a liquid, under the effect of a localized upward flow injected through a small orifice at the bottom of the bed. Visualization inside the model granular medium consisting of glass beads is made possible by the combined use of two optical techniques: refractive index matching between the liquid and the beads and planar laser-induced fluorescence. Gradually increasing the injection rate, three regimes are successively observed: static bed, fluidized cavity that does not open to the upper surface of the granular bed, and finally fluidization over the entire height of the granular bed inside a fluidized chimney. The phase diagram is plotted and partially interpreted using a model previously developed by Zoueshtiagh and Merlen [F. Zoueshtiagh and A. Merlen, Phys. Rev. E 75, 053613 (2007)]. A typical sequence, where the flow rate is first increased and then decreased back to zero, reveals a strong hysteretic behavior since the stability of the fluidized cavity is considerably strengthened during the defluidization phase. This effect can be explained by the formation of force arches within the granular packing when the chimney closes up at the top of the bed. A study of the expansion rate of the fluidized cavity was also conducted as well as the analysis of the interaction between two injection orifices with respect to their spacing.

  14. Electrically enhanced fluidized bed heat exchanger

    SciTech Connect

    Lessor, D.L.; Robertus, R.J.; Roberts, G.L.

    1994-05-01

    The experiments have shown that a high level of electrical charging can be achieved in a fluidized bed of two resistive particle types; that bed stabilization rather than increased sensible heat transport dominates low frequency electric field effects on heat transfer with most bed loadings; and, hence, that applying an oscillatory potential difference between tubes or rods in a fluidized bed of two mutual contact-charging particle species gives reduced rather than improved heat transfer. Applying an oscillatory potential difference between rods in a bed of quartz particles fluidized alone did give improved heat transfer, however. With no electric field applied, most fluidized mixes were found to give higher heat transfer rates than the average of the values when each of the two species was fluidized alone. The high level of charging observed in some mixed beds may prove of interest for some air cleanup applications; the results show that simultaneous fluidization of pairs of bipolar charging materials of similar particle size is possible without excessive agglomeration. This would be important for air cleanup.

  15. Spectral methods applied to fluidized-bed combustors

    SciTech Connect

    Brown, R.C.; Raines, T.S.; Thiede, T.D.

    1995-11-01

    The goal of this research is to characterize coals and sorbents during the normal operation of an industrial-scale circulating fluidized bed (CFB) boiler. The method determines coal or sorbent properties based on the analysis of transient CO{sub 2} or SO{sub 2} emissions from the boiler. Fourier Transform Infrared (FTIR) spectroscopy is used to qualitatively and quantitatively analyze the gaseous products of combustion. Spectral analysis applied to the transient response of CO{sub 2} and SO{sub 2} resulting from introduction of a batch of coal or limestone into the boiler yields characteristic time constants from which combustion or sorbent models are developed. The method is non-intrusive and is performed under realistic combustion conditions. Results are presented from laboratory studies and power plant monitoring.

  16. Liquid-solid extraction coupled with magnetic solid-phase extraction for determination of pyrethroid residues in vegetable samples by ultra fast liquid chromatography.

    PubMed

    Jiang, Chunzhu; Sun, Ying; Yu, Xi; Gao, Yan; Zhang, Lei; Wang, Yuanpeng; Zhang, Hanqi; Song, Daqian

    2013-09-30

    In this study, liquid-solid extraction coupled with magnetic solid-phase extraction was successfully developed for the extraction of pyrethroid residues in vegetable samples. The analytes were determined by ultra fast liquid chromatography. The pyrethroids were extracted by liquid-solid extraction and then adsorbed onto magnetic adsorbent. Magnetic adsorbent, C18-functionalized ultrafine magnetic silica nanoparticles, was synthesized by chemical coprecipitation, silanization and alkylation. The analytes adsorbed onto the magnetic adsorbent can be simply and rapidly isolated from sample solution with a strong magnet on the bottom of the extraction vessel. The extraction parameters, such as liquid-solid extraction solvent, liquid-solid extraction time, the amount of magnetic adsorbent, magnetic solid-phase extraction time and magnetic solid-phase extraction desorption solvent, were optimized to improve the extraction efficiency. The analytical performances of this method, including linear range, detection limit, precision, and recovery were evaluated. The limits of detection for pyrethroid were between 0.63 and 1.2 ng g(-1). Recoveries obtained by analyzing the four spiked vegetable samples were between 76.0% and 99.5%. The results showed that the present method was a simple, accurate and high efficient approach for the determination of pyrethroids in the vegetable samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Velocity Fluctuations in Gas-Fluidized Beds

    NASA Astrophysics Data System (ADS)

    Cody, G. D.

    1998-03-01

    Increasing gas flow through a bed of particles produces, above a sharp threshold, a fluidized state which exhibits many of the properties of a liquid. Fluidized beds play a major role in refining, chemicals, and power generation, but the physics of the fluidized state is still uncertain, due to the complexity of the particle/gas interactions, the broad distribution of particle size, and the measurement challenge. One consequence can be the failure of sophisticated computer models to predict performance. Another is the failure to resolve fundamental questions, for example the source of the initial stability/instability of the uniform fluidized state, first addressed by Jackson in 1963(R. Jackson, in Fluidization, edited by J. F. Davidson et al. (Academic Press, New York, 1985), p. 47-72; G. K. Batchelor, J. Fluid Mech. 193, 75-110 (1988); M. Nicolas. J. Chomaz, and E. Guazelli, Phys. Fluids 6, 3936-3944 (1994).). To meet the measurement challenge, we have obtained the first comprehensive data on the mean squared fluctuation velocity, or granular temperature, T*, of monodispersed glass spheres of diameter, D, in a fluidized bed, by a novel acoustic shot noise probe of random particle impact on the wall(G. D. Cody, D. J. Goldfarb, G. V. Storch, Jr., A. N. Norris, Powder Technology 87, 211-232 (1996); G. D. Cody and D. J. Goldfarb, in Dynamics in Small Confining Systems-III, eds. M. Drake et al, (MRS, Pittsburgh, Pa, 1997), 464, p. 325-338.). Applying a dense gas kinetic model(D. Gidaspow, Multiphase Flow and Fluidization (Academic Press, San Diego, 1994).) to this data predicts values of particulate pressure, and viscosity, which are in excellent agreement with recent experiments, and encouraged us to revisit the stability question. We find that the unanticipated seven-fold bifurcation observed in T* for D less than 150 microns is sufficient, using Jackson's model, to account for the accepted empirical boundary of stable initial uniform fluidization for the spheres

  18. 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% H2, 20% CO, 20% CO2 and 5% CH4. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Solids mixing in bubbling fluidized beds: CFD-based analysis of Bubble Dynamics and Time Scales

    NASA Astrophysics Data System (ADS)

    Bakshi, Akhilesh; Altantzis, Christos; Ghoniem, Ahmed

    2016-11-01

    In bubbling fluidized bed reactors, solids mixing is critical because it directly affects fuel segregation and residence time. However, there continues to be a lack of understanding because (a) most diagnostic techniques are only feasible in lab-scale setups and (b) the dynamics are sensitive to the operating conditions. Thus, quantitative estimates of mixing (e.g., dispersion coefficient, mixing indices) often span orders of magnitude although it is well accepted that the micro-mixing and gross circulation of solid particles is driven by bubble motion. To quantify this dependence, solids mixing is investigated using fine-grid 3D CFD simulations of a large 50 cm diameter fluidized bed. Detailed diagnostics of the computed flow-field data are performed using MS3DATA, a tool that we developed to detect and track bubbles, and the solids motion is correlated with the spatial and size distribution of bubbles. This study will be useful for quantifying mixing at commercial scales.

  20. THE SCALE-UP OF LARGE PRESSURIZED FLUIDIZED BEDS FOR ADVANCED COAL FIRED PROCESSES

    SciTech Connect

    Leon Glicksman; Hesham Younis; Richard Hing-Fung Tan; Michel Louge; Elizabeth Griffith; Vincent Bricout

    1998-04-30

    Pressurized fluidization is a promising new technology for the clean and efficient combustion of coal. Its principle is to operate a coal combustor at high inlet gas velocity to increase the flow of reactants, at an elevated pressure to raise the overall efficiency of the process. Unfortunately, commercialization of large pressurized fluidized beds is inhibited by uncertainties in scaling up units from the current pilot plant levels. In this context, our objective is to conduct a study of the fluid dynamics and solid capture of a large pressurized coal-fired unit. The idea is to employ dimensional similitude to simulate in a cold laboratory model the flow in a Pressurized Circulating Fluid Bed ''Pyrolyzer,'' which is part of a High Performance Power System (HIPPS) developed by Foster Wheeler Development Corporation (FWDC) under the DOE's Combustion 2000 program.

  1. Development of a FI CIRC{trademark} fluidized bed boiler to burn waste tires

    SciTech Connect

    Dervin, C.; Waldron, D.J.; Haas, J.C.

    1997-12-31

    Disposal of tires is becoming a problem due to higher landfill charges and environmental concerns. Typically tires have a higher calorific value than coal, contain less nitrogen, ash, and sulfur than most coals and are a potential source of energy for power and process steam generation. In 1995 a Fines Circulating (FI CIRC{trademark}) fluidized bed boiler was selected to burn tires for a project in the city of Fulton, Illinois. Fuels ranging from Petroleum Coke to Brown coal had already been successfully fired in commercial plants and preliminary pilot plant testing showed no problems in firing tires. During the development of the project, financiers raised concerns about the optimum fuel size, combustion characteristics, removal of wires from the fluidized bed, and the control of emissions from the plant. A testing program was devised which included hot and cold pilot plant testing to evaluate the characteristics of firing shredded tires. The results and the impact on the boiler design are presented.

  2. Fluidized bed charcoal particle production system

    SciTech Connect

    Sowards, N.K.

    1985-04-09

    A fluidized bed charcoal particle production system, including apparatus and method, wherein pieces of combustible waste, such as sawdust, fragments of wood, etc., are continuously disposed within a fluidized bed of a pyrolytic vessel. Preferably, the fluidized bed is caused to reach operating temperatures by use of an external pre-heater. The fluidized bed is situated above an air delivery system at the bottom of the vessel, which supports pyrolysis within the fluidized bed. Charcoal particles are thus formed within the bed from the combustible waste and are lifted from the bed and placed in suspension above the bed by forced air passing upwardly through the bed. The suspended charcoal particles and the gaseous medium in which the particles are suspended are displaced from the vessel into a cyclone mechanism where the charcoal particles are separated. The separated charcoal particles are quenched with water to terminate all further charcoal oxidation. The remaining off-gas is burned and, preferably, the heat therefrom used to generate steam, kiln dry lumber, etc. Preferably, the bed material is continuously recirculated and purified by removing tramp material.

  3. 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.

  4. Rivesville multicell fluidized bed boiler

    SciTech Connect

    Not Available

    1981-03-01

    One objective of the experimental MFB at Rivesville, WV, was the evaluation of alternate feed systems for injecting coal and limestone into a fluidized bed. A continuous, uniform feed flow to the fluid bed is essential in order to maintain stable operations. The feed system originally installed on the MFB was a gravity feed system with an air assist to help overcome the back pressure created by the fluid bed. The system contained belt, vibrating, and rotary feeders which have been proven adequate in other material handling applications. This system, while usable, had several operational and feeding problems during the MFB testing. A major portion of these problems occurred because the coal and limestone feed control points - a belt feeder and rotary feeder, respectively - were pressurized in the air assist system. These control points were not designed for pressurized service. An alternate feed system which could accept feed from the two control points, split the feed into six equal parts and eliminate the problems of the pressurized system was sought. An alternate feed system designed and built by the Fuller Company was installed and tested at the Rivesville facility. Fuller feed systems were installed on the north and south side of C cell at the Rivesville facility. The systems were designed to handle 10,000 lb/hr of coal and limestone apiece. The systems were installed in late 1979 and evaluated from December 1979 to December 1980. During this time period, nearly 1000 h of operating time was accumulated on each system.

  5. Pressurized fluidized-bed combustion

    SciTech Connect

    Not Available

    1980-10-01

    The US DOE pressurized fluidized bed combustion (PFBC) research and development program is designed to develop the technology and data base required for the successful commercialization of the PFBC concept. A cooperative program with the US, West Germany, and the UK has resulted in the construction of the 25 MWe IEA-Grimethorpe combined-cycle pilot plant in England which will be tested in 1981. A 13 MWe coal-fired gas turbine (air cycle) at Curtis-Wright has been designed and construction scheduled. Start-up is planned to begin in early 1983. A 75 MWe pilot plant is planned for completion in 1986. Each of these PFBC combined-cycle programs is discussed. The current status of PFB technology may be summarized as follows: turbine erosion tolerance/hot gas cleanup issues have emerged as the barrier technology issues; promising turbine corrosion-resistant materials have been identified, but long-term exposure data is lacking; first-generation PFB combustor technology development is maturing at the PDU level; however, scale-up to larger size has not been demonstrated; and in-bed heat exchanger materials have been identified, but long-term exposure data is lacking. The DOE-PFB development plan is directed at the resolution of these key technical issues. (LCL)

  6. Reflection at a liquid-solid interface of a transient ultrasonic field radiated by a linear phased array transducer.

    PubMed

    Maghlaoui, Nadir; Belgroune, Djema; Ourak, Mohamed; Djelouah, Hakim

    2016-09-01

    In order to put in evidence the specular reflection and the non-specular reflection in the transient case, we have used a model for the study of the transient ultrasonic waves radiated by a linear phased array transducer in a liquid and reflected by a solid plane interface. This method is an extension of the angular spectrum method to the transient case where the reflection at the plane interface is taken into account by using the reflection coefficient for harmonic plane waves. The results obtained highlighted the different components of the ultrasonic field: the direct and edge waves as well as the longitudinal head waves or leaky Rayleigh waves. The transient representation of these waves have been carefully analyzed and discussed by the rays model. Instantaneous cartographies allowed a clear description of all the waves which appear at the liquid-solid interface. The obtained results have been compared to those obtained with a finite element method package. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Nanophase diagram of binary eutectic Au-Ge nanoalloys for vapor-liquid-solid semiconductor nanowires growth

    PubMed Central

    Lu, Haiming; Meng, Xiangkang

    2015-01-01

    Although the vapor-liquid-solid growth of semiconductor nanowire is a non-equilibrium process, the equilibrium phase diagram of binary alloy provides important guidance on the growth conditions, such as the temperature and the equilibrium composition of the alloy. Given the small dimensions of the alloy seeds and the nanowires, the known phase diagram of bulk binary alloy cannot be expected to accurately predict the behavior of the nanowire growth. Here, we developed a unified model to describe the size- and dimensionality-dependent equilibrium phase diagram of Au-Ge binary eutectic nanoalloys based on the size-dependent cohesive energy model. It is found that the liquidus curves reduce and shift leftward with decreasing size and dimensionality. Moreover, the effects of size and dimensionality on the eutectic composition are small and negligible when both components in binary eutectic alloys have the same dimensionality. However, when two components have different dimensionality (e.g. Au nanoparticle-Ge nanowire usually used in the semiconductor nanowires growth), the eutectic composition reduces with decreasing size. PMID:26053237

  8. Nanophase diagram of binary eutectic Au-Ge nanoalloys for vapor-liquid-solid semiconductor nanowires growth.

    PubMed

    Lu, Haiming; Meng, Xiangkang

    2015-06-08

    Although the vapor-liquid-solid growth of semiconductor nanowire is a non-equilibrium process, the equilibrium phase diagram of binary alloy provides important guidance on the growth conditions, such as the temperature and the equilibrium composition of the alloy. Given the small dimensions of the alloy seeds and the nanowires, the known phase diagram of bulk binary alloy cannot be expected to accurately predict the behavior of the nanowire growth. Here, we developed a unified model to describe the size- and dimensionality-dependent equilibrium phase diagram of Au-Ge binary eutectic nanoalloys based on the size-dependent cohesive energy model. It is found that the liquidus curves reduce and shift leftward with decreasing size and dimensionality. Moreover, the effects of size and dimensionality on the eutectic composition are small and negligible when both components in binary eutectic alloys have the same dimensionality. However, when two components have different dimensionality (e.g. Au nanoparticle-Ge nanowire usually used in the semiconductor nanowires growth), the eutectic composition reduces with decreasing size.

  9. Comparison of gamma-densitometry tomography and electrical-impedance tomography for determining material distribution in liquid-solid flows

    SciTech Connect

    Shollenberger, K.A.; Torczynski, J.R.; O`Hern, T.J.; Adkins, D.R.; Ceccio, S.L.; George, D.L.

    1997-03-01

    The spatial distribution of materials in multiphase flows is of importance to many industrial processes. For example, in indirect coal liquefaction, a reactive gas is bubbled through a catalyst-laden liquid (slurry), and a spatially nonuniform gas distribution can reduce process efficiency by inducing large-scale buoyancy-driven recirculating flows. Gamma-densitometry tomography (GDT) and electrical-impedance tomography (EIT) are techniques with the potential of providing spatially resolved information on material distribution in multiphase flows. GDT and EIT have both been applied to a liquid-solid flow for comparison purposes. The experiment consisted of a cylinder (19 cm diameter) filled with water, in which 80 {micro}m glass spheres were suspended by a mixer to achieve solid volume fractions of 0.01, 0.02, and 0.03. Both GDT and EIT revealed a relatively uniform distribution of solids in the measurement plane, and the average solid volume fractions from both techniques were in good agreement.

  10. Eulerian-Lagrangian large eddy simulations of dense liquid-solid slurry flow through a horizontal pipe

    NASA Astrophysics Data System (ADS)

    Arolla, Sunil; Capecelatro, Jesse; Desjardins, Olivier

    2013-11-01

    A high-fidelity large eddy simulation based Eulerian-Lagrangian methodology is used to investigate the detailed dynamics of liquid-solid slurries in a horizontal pipe. A dynamic Smagorinsky model based on Lagrangian averaging is employed to account for the sub-grid scale effects in the liquid phase. A fully conservative immersed boundary method is used to account for the pipe geometry on a uniform cartesian grid. The liquid and solid phases are coupled through volume fraction and the momentum exchange terms. Particle-particle and particle-wall collisions are modeled using a soft-sphere approach. Mean particle concentration and velocity profiles are computed, showing excellent agreement with experimental data. Covariance statistics are extracted and compared against multiphase turbulence models in the literature. When the bulk liquid velocity is below the critical deposition velocity, particles form a static bed at the bottom that exhibits strong size segregation. Based on our numerical simulations, a critical value for the Froude number is proposed below which the solid particles starts depositing.

  11. Graphene-Analogues Boron Nitride Nanosheets Confining Ionic Liquids: A High-Performance Quasi-Liquid Solid Electrolyte.

    PubMed

    Li, Mingtao; Zhu, Wenshuai; Zhang, Pengfei; Chao, Yanhong; He, Qian; Yang, Bolun; Li, Huaming; Borisevich, Albinab; Dai, Sheng

    2016-07-01

    Solid electrolytes are one of the most promising electrolyte systems for safe lithium batteries, but the low ionic conductivity of these electrolytes seriously hinders the development of efficient lithium batteries. Here, a novel class of graphene-analogues boron nitride (g-BN) nanosheets confining an ultrahigh concentration of ionic liquids (ILs) in an interlayer and out-of-layer chamber to give rise to a quasi-liquid solid electrolyte (QLSE) is reported. The electron-insulated g-BN nanosheet host with a large specific surface area can confine ILs as much as 10 times of the host's weight to afford high ionic conductivity (3.85 × 10(-3) S cm(-1) at 25 °C, even 2.32 × 10(-4) S cm(-1) at -20 °C), which is close to that of the corresponding bulk IL electrolytes. The high ionic conductivity of QLSE is attributed to the enormous absorption for ILs and the confining effect of g-BN to form the ordered lithium ion transport channels in an interlayer and out-of-layer of g-BN. Furthermore, the electrolyte displays outstanding electrochemical properties and battery performance. In principle, this work enables a wider tunability, further opening up a new field for the fabrication of the next-generation QLSE based on layered nanomaterials in energy conversion devices.

  12. Use of phosphine as an n-type dopant source for vapor-liquid-solid growth of silicon nanowires.

    PubMed

    Wang, Yanfeng; Lew, Kok-Keong; Ho, Tsung-Ta; Pan, Ling; Novak, Steven W; Dickey, Elizabeth C; Redwing, Joan M; Mayer, Theresa S

    2005-11-01

    Phosphine (PH3) was investigated as an n-type dopant source for Au-catalyzed vapor-liquid-solid (VLS) growth of phosphorus-doped silicon nanowires (SiNWs). Transmission electron microscopy characterization revealed that the as-grown SiNWs were predominately single crystal even at high phosphorus concentrations. Four-point resistance and gate-dependent conductance measurements confirmed that electrically active phosphorus was incorporated into the SiNWs during VLS growth. A transition was observed from p-type conduction for nominally undoped SiNWs to n-type conduction upon the introduction of PH3 to the inlet gas. The resistivity of the n-type SiNWs decreased by approximately 3 orders of magnitude as the inlet PH3 to silane (SiH4) gas ratio was increased from 2 x 10(-5) to 2 x 10(-3). These results demonstrate that PH3 can be used to produce n-type SiNWs with properties that are suitable for electronic and optoelectronic device applications.

  13. Liquid-liquid-solid microextraction and detection of nerve agent simulants by on-membrane Fourier transform infrared spectroscopy.

    PubMed

    Garg, Prabhat; Purohit, Ajay; Tak, Vijay K; Kumar, Ajeet; Dubey, D K

    2012-11-02

    A coupling of novel liquid-liquid-solid microextraction (LLSME) technique based on porous hydrophobic membrane and Fourier-transform infrared spectroscopy has been presented for the detection, identification and quantification of markers and simulants of nerve agents. Two isomers O,O'-dihexyl methylphosphonate (DHMP) and O,O'-dipentyl isopropylphosphonate (DPIPP) were chosen as model analytes for the study. In the present technique, organic phase was immobilised within the pores of membrane after fixing it in an assembly, which was then immersed into aqueous sample of target analytes for extraction. The analytes were directly determined on the surface of membrane by FTIR spectroscopy without elution. On comparison with solid phase microextraction (SPME), LLSME was found to be much more efficient. The method was optimised and quantitative analyses were performed using calibration curves obtained via Beer's law and employing processing of spectra obtained, via a multivariate calibration technique partial least square (PLS). Relative standard deviations (RSDs) for intraday repeatability and interday reproducibility were found to be in the range of 0.20-0.50% and 0.20-0.60%, respectively. Limit of detection (LOD) was achieved up to 15 ng mL(-1). Applicability of the method was tested with an unknown real sample obtained in an international official proficiency test (OPT).

  14. Highly patterned growth of SnO2 nanowires using a sub-atmospheric vapor-liquid-solid deposition

    NASA Astrophysics Data System (ADS)

    Akbari, M.; Mohajerzadeh, S.

    2017-08-01

    We report the realization of tin-oxide nanowires on patterned structures using a vapor-liquid-solid (VLS) process. While gold acts as the catalyst for the growth of wires, a tin-oxide containing sol-gel solution is spin coated on silicon substrate to act as the source for SnO vapor. The growth of tin-oxide nano-structures occurs mostly at the vicinity of the pre-deposited solution. By patterning the gold as the catalyst material, one is able to observe the growth at desired places. The growth of nanowires is highly dense within 100 µm away from such in situ source and their length is of the order of 5 µm. By further distancing from the source, the growth becomes more limited and nanowires become shorter and more sparsely distributed. The growth of nanowires has been studied using scanning and transmission electron microscopy tools while their composition has been investigated using XRD and EDS analyses. As a novel application, we have employed the grown nanowires as electron detection elements to measure the emitted electrons from electron sources. This configuration can be further used as electron detectors for scanning electron microscopes.

  15. Research on wear properties of centrifugal dredge pump based on liquid-solid two-phase fluid simulations

    NASA Astrophysics Data System (ADS)

    Peng, G. J.; Luo, Y. Y.; Wang, Z. W.

    2015-01-01

    The impeller and casing of dredge pump are worn by sediment in the flow. However, there are few studies about abrasion of the impeller and casing for normal pump operating conditions. This paper investigated the relationship between the wear rates on the surfaces of the impeller as well as casing and the sediment concentration, with the distribution of the wear rates for normal pump operating condition analyzed. An Eulerian-Lagrangian Computational Fluid Dynamics (CFD) procedure was used to simulate steady liquid-solid two-phase flow for various operating conditions. The Finnie model was then used to predict the abrasion. The results show that, the wear rate relative value of impeller and casing surface increase as the sediment concentration increases. The wear rate relative value of impeller and casing surface is larger when the pump is in low flow rate condition, and the value of casing surface is larger than that of the impeller. The wear rate relative value of pump is low when pump is in high efficiency condition. This paper shows the abrasion characteristics on the impeller and casing with sediment flow and provides reference data for predicting the abrasion conditions in the flow passage components for a dredge pump.

  16. Towards engineered branch placement: Unreal™ match between vapour-liquid-solid glancing angle deposition nanowire growth and simulation

    SciTech Connect

    Taschuk, M. T.; Tucker, R. T.; LaForge, J. M.; Beaudry, A. L.; Kupsta, M. R.; Brett, M. J.

    2013-12-28

    The vapour-liquid-solid glancing angle deposition (VLS-GLAD) process is capable of producing complex nanotree structures with control over azimuthal branch orientation and height. We have developed a thin film growth simulation including ballistic deposition, simplified surface diffusion, and droplet-mediated cubic crystal growth for the VLS-GLAD process using the Unreal{sup TM} Development Kit. The use of a commercial game engine has provided an interactive environment while allowing a custom physics implementation. Our simulation's output is verified against experimental data, including a volumetric film reconstruction produced using focused ion beam and scanning-electron microscopy (SEM), crystallographic texture, and morphological characteristics such as branch orientation. We achieve excellent morphological and texture agreement with experimental data, as well as qualitative agreement with SEM imagery. The simplified physics in our model reproduces the experimental films, indicating that the dominant role flux geometry plays in the VLS-GLAD competitive growth process responsible for azimuthally oriented branches and biaxial crystal texture evolution. The simulation's successful reproduction of experimental data indicates that it should have predictive power in designing novel VLS-GLAD structures.

  17. 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.

  18. 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.

  19. 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.

  20. Types of gas fluidization of cohesive granular materials.

    PubMed

    Valverde, Jose Manuel; Castellanos, Antonio

    2007-03-01

    Some years ago it was shown that gas-fluidized powders may transit from solid-like to fluid-like fluidization prior to bubbling, shedding light on a long-standing controversy on the nature of "homogeneous" fluidization. In this paper it is shown that some gas-fluidized powders may also transit from the fluid-like regime to elutriation, with full suppression of the bubbling regime. We provide a diagram that can be used to predict these types of fluidization exhibited by cohesive powders based on simple phenomenological equations in which particle aggregation due to attractive forces is a key ingredient.

  1. Types of gas fluidization of cohesive granular materials

    NASA Astrophysics Data System (ADS)

    Valverde, Jose Manuel; Castellanos, Antonio

    2007-03-01

    Some years ago it was shown that gas-fluidized powders may transit from solidlike to fluidlike fluidization prior to bubbling, shedding light on a long-standing controversy on the nature of “homogeneous” fluidization. In this paper it is shown that some gas-fluidized powders may also transit from the fluidlike regime to elutriation, with full suppression of the bubbling regime. We provide a diagram that can be used to predict these types of fluidization exhibited by cohesive powders based on simple phenomenological equations in which particle aggregation due to attractive forces is a key ingredient.

  2. 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.

  3. Fluidized bed catalytic coal gasification process

    DOEpatents

    Euker, Jr., Charles A.; Wesselhoft, Robert D.; Dunkleman, John J.; Aquino, Dolores C.; Gouker, Toby R.

    1984-01-01

    Coal or similar carbonaceous solids impregnated with gasification catalyst constituents (16) are oxidized by contact with a gas containing between 2 volume percent and 21 volume percent oxygen at a temperature between 50.degree. C. and 250.degree. C. in an oxidation zone (24) and the resultant oxidized, catalyst impregnated solids are then gasified in a fluidized bed gasification zone (44) 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.

  4. Fluidized bed pyrolysis to gases containing olefins

    SciTech Connect

    Kuester, J.L.

    1980-01-01

    Recent gasification data are presented for a system designed to produce liquid hydrocarbon fuel from various biomass feedstocks. The factors under investigation were feedstock type, fluidizing gas type, residence time, temperature and catalyst usage. The response was gas phase composition. A fluidized bed system was utilized with a separate regenerator-combustor. An olefin content as high as 39 mole % was achieved. Hydrogen/carbon monoxide ratios were easily manipulated via steam addition over a broad range with an autocatalytic effect apparent for most feedstocks.

  5. 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.

  6. Synthesis of epitaxial Si(100) nanowires on Si(100) substrate using vapor liquid solid growth in anodic aluminum oxide nanopore arrays

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Senz, S.; Shingubara, S.; Gösele, U.

    2007-06-01

    The synthesis of epitaxial Si nanowires with growth direction parallel to Si [100] on Si(100) substrate was demonstrated using a combination of anodic aluminum oxide (AAO) template, catalytic gold film sandwiched between the template and the Si(100) substrate and vapor-liquid-solid growth using SiH4 as the Si source. After growing out from the AAO nanopores, most Si nanowires changed their diameter and growth direction into larger diameter and <111> direction.

  7. Local pressure components and interfacial tension at a liquid-solid interface obtained by the perturbative method in the Lennard-Jones system

    NASA Astrophysics Data System (ADS)

    Fujiwara, K.; Shibahara, M.

    2014-07-01

    A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the local pressure components and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the numerical results is examined through the comparison of the results obtained by each method. The calculated local pressure components and interfacial tension of the fluid at a liquid-solid interface agreed well with the results of the two alternative methods at each local position in one dimension. In two dimensions, the results showed a characteristic profile of the tangential pressure component which depended on the direction tangential to the liquid-solid interface, which agreed with that obtained by the evaluation of the intermolecular force acting on a plane in the present study. Such good agreement suggests that the perturbative method on the basis of statistical thermodynamics used in this study is valid to obtain the local pressure components and interfacial tension at a liquid-solid interface.

  8. Local pressure components and interfacial tension at a liquid-solid interface obtained by the perturbative method in the Lennard-Jones system.

    PubMed

    Fujiwara, K; Shibahara, M

    2014-07-21

    A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the local pressure components and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the numerical results is examined through the comparison of the results obtained by each method. The calculated local pressure components and interfacial tension of the fluid at a liquid-solid interface agreed well with the results of the two alternative methods at each local position in one dimension. In two dimensions, the results showed a characteristic profile of the tangential pressure component which depended on the direction tangential to the liquid-solid interface, which agreed with that obtained by the evaluation of the intermolecular force acting on a plane in the present study. Such good agreement suggests that the perturbative method on the basis of statistical thermodynamics used in this study is valid to obtain the local pressure components and interfacial tension at a liquid-solid interface.

  9. Local pressure components and interfacial tension at a liquid-solid interface obtained by the perturbative method in the Lennard-Jones system

    SciTech Connect

    Fujiwara, K.; Shibahara, M.

    2014-07-21

    A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the local pressure components and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the numerical results is examined through the comparison of the results obtained by each method. The calculated local pressure components and interfacial tension of the fluid at a liquid-solid interface agreed well with the results of the two alternative methods at each local position in one dimension. In two dimensions, the results showed a characteristic profile of the tangential pressure component which depended on the direction tangential to the liquid-solid interface, which agreed with that obtained by the evaluation of the intermolecular force acting on a plane in the present study. Such good agreement suggests that the perturbative method on the basis of statistical thermodynamics used in this study is valid to obtain the local pressure components and interfacial tension at a liquid-solid interface.

  10. Method and equipment for treatment of fuel for fluidized bed combustion

    SciTech Connect

    Beranek, J.; Cermak, J.; Dobrozemsky, J.; Fibinger, V.

    1982-04-20

    The invention relates to the method and equipment for treatment of fuel for fluidized bed combustion, which includes drying, classification and crushing of the fuel. The method for treatment of fuel comprises mixing the fuel with hot ash removed from the fluidized bed combustor and drying said mixture in a fluidized bed dryer in which the velocity of the fluidization fluid equals or is lower than the minimum fluidization velocity of particles in the fluidized bed combustor. The equipment for treatment of fuel comprises a bunker, crusher and dryer, comprising a fluidized bed dryer provided with appropriate piping for interconnection of the fluidized bed dryer, fluidized bed combuster, fuel bunker and crusher.

  11. Method and equipment for treatment of fuel for fluidized bed combustion

    SciTech Connect

    Beranek, J.; Dobrozemsky, J.; Fibinger, V.; Germak, J.

    1983-11-15

    The invention relates to the method and equipment for treatment of fuel for fluidized bed combustion, which includes drying, classification and crushing of the fuel. The method for treatment of fuel comprises mixing the fuel with hot ash removed from the fluidized bed combustor and drying said mixture in a fluidized bed dryer in which the velocity of the fluidization fluid equals or is lower than the minimum fluidization velocity of particles in the fluidized bed combustor. The equipment for treatment of fuel comprises a bunker, crusher and dryer, comprising a fluidized bed dryer provided with appropriate piping for interconnection of the fluidized bed dryer, fluidized bed combustor, fuel bunker and crusher.

  12. Analysis of the vapor-liquid-solid mechanism for nanowire growth and a model for this mechanism.

    PubMed

    Mohammad, S Noor

    2008-05-01

    The vapor-liquid-solid (VLS) mechanism is most widely employed to grow nanowires (NWs). The mechanism uses foreign element catalytic agent (FECA) to mediate the growth. Because of this, it is believed to be very stable with the FECA-mediated droplets not consumed even when reaction conditions change. Recent experiments however differ, which suggest that even under cleanest growth conditions, VLS mechanism may not produce long, thin, uniform, single-crystal nanowires of high purity. The present investigation has addressed various issues involving fundamentals of VLS growth. While addressing these issues, it has taken into consideration the influence of the electrical, hydrodynamic, thermodynamic, and surface tension effects on NW growth. It has found that parameters such as mesoscopic effects on nanoparticle seeds, charge distribution in FECA-induced droplets, electronegativity of the droplet with respect to those of reactive nanowire vapor species, growth temperature, and chamber pressure play important role in the VLS growth. On the basis of an in-depth analysis of various issues, a simple, novel, malleable (SNM) model has been presented for the VLS mechanism. The model appears to explain the formation and observed characteristics of a wide variety of nanowires, including elemental and compound semiconductor nanowires. Also it provides an understanding of the influence of the dynamic behavior of the droplets on the NW growth. This study finds that increase in diameter with time of the droplet of tapered nanowires results primarily from gradual incorporation of oversupplied nanowire species into the FECA-mediated droplet, which is supported by experiments. It finds also that optimum compositions of the droplet constituents are crucial for VLS nanowire growth. An approximate model presented to exemplify the parametric dependency of VLS growth provides good description of NW growth rate as a function of temperature.

  13. Host-Guest Chemistry in Integrated Porous Space Formed by Molecular Self-Assembly at Liquid-Solid Interfaces.

    PubMed

    Iritani, Kohei; Tahara, Kazukuni; De Feyter, Steven; Tobe, Yoshito

    2017-02-23

    Host-guest chemistry in two-dimensional (2D) space, that is, physisorbed monolayers of a single atom or a single molecular thickness on surfaces, has become a subject of intense current interest because of perspectives for various applications in molecular-scale electronics, selective sensors, and tailored catalysis. Scanning tunneling microscopy has been used as a powerful tool for the visualization of molecules in real space on a conducting substrate surface. For more than a decade, we have been investigating the self-assembly of a series of triangle-shaped phenylene-ethynylene macrocycles called dehydrobenzo[12]annulenes (DBAs). These molecules are substituted with six alkyl chains and are capable of forming hexagonal porous 2D molecular networks via van der Waals interactions between interdigitated alkyl chains at the interface of organic solvents and graphite. The dimension of the nanoporous space or nanowell formed by the self-assembly of DBAs can be controlled from 1.6 to 4.7 nm by simply changing the alkyl chain length from C6 to C20. Single molecules as well as homoclusters and heteroclusters are capable of coadsorbing within the host matrix using shape- and size-complementarity principles. Moreover, on the basis of the versatility of the DBA molecules that allows chemical modification of the alkyl chain terminals, we were able to decorate the interior space of the nanoporous networks with functional groups such as azobenzenedicarboxylic acid for photoresponsive guest adsorption/desorption or fluoroalkanes and tetraethylene glycol groups for selective guest binding by electrostatic interactions and zinc-porphyrin units for complexation with a guest by charge-transfer interactions. In this Feature Article, we describe the general aspects of molecular self-assembly at liquid/solid interfaces, followed by the formation of programmed porous molecular networks using rationally designed molecular building blocks. We focus on our own work involving host

  14. Localized fluidization burrowing mechanics of Ensis directus.

    PubMed

    Winter, Amos G; Deits, Robin L H; Hosoi, A E

    2012-06-15

    Muscle measurements of Ensis directus, the Atlantic razor clam, indicate that the organism only has sufficient strength to burrow a few centimeters into the soil, yet razor clams burrow to over 70 cm. In this paper, we show that the animal uses the motions of its valves to locally fluidize the surrounding soil and reduce burrowing drag. Substrate deformations were measured using particle image velocimetry (PIV) in a novel visualization system that enabled us to see through the soil and watch E. directus burrow in situ. PIV data, supported by soil and fluid mechanics theory, show that contraction of the valves of E. directus locally fluidizes the surrounding soil. Particle and fluid mixtures can be modeled as a Newtonian fluid with an effective viscosity based on the local void fraction. Using these models, we demonstrate that E. directus is strong enough to reach full burrow depth in fluidized soil, but not in static soil. Furthermore, we show that the method of localized fluidization reduces the amount of energy required to reach burrow depth by an order of magnitude compared with penetrating static soil, and leads to a burrowing energy that scales linearly with depth rather than with depth squared.

  15. Particle pressures in fluidized beds. Final report

    SciTech Connect

    Campbell, C.S.; Rahman, K.; Jin, C.

    1996-09-01

    This project studies the particle pressure, which may be thought of as the force exerted by the particulate phase of a multiphase mixture, independently of that exerted by other phases. The project is divided into two parts, one concerning gas and the other liquid fluidized beds. Previous work on gas fluidized beds had suggested that the particle pressures are generated by bubbling action. Thus, for these gas fluidized bed studies, the particle pressure is measured around single bubbles generated in 2-D fluidized beds, using special probes developed especially for this purpose. Liquid beds are immune from bubbling and the particle pressures proved too small to measure directly. However, the major interest in particle pressures in liquid beds lies in their stabilizing effect that arises from the effective elasticity (the derivative of the particle pressure with respect to the void fraction), they impart to the bed. So rather than directly measure the particle pressure, the authors inferred the values of the elasticity from measurements of instability growth in liquid beds; the inference was made by first developing a generic stability model (one with all the normally modeled coefficients left undetermined) and then working backwards to determine the unknown coefficients, including the elasticity.

  16. Particle Pressures in Fluidized Beds. Final report

    SciTech Connect

    Campbell, C.S.; Rahman, K.; Jin, C.

    1996-09-01

    This project studies the particle pressure, which may be thought of as the force exerted by the particulate phase of a multiphase mixture, independently of that exerted by other phases. The project is divided into two parts, one concerning gas and the other liquid fluidized beds. Previous work on gas fluidized beds had suggested that the particle pressures are generated by bubbling action. Thus, for these gas fluidized bed studies, the particle pressure is measured around single bubbles generated in 2-D fluidized beds, using special probes developed especially for this purpose. Liquid beds are immune from bubbling and the particle pressures proved too small to measure directly. However, the major interest in particle pressures in liquid beds lies in their stabilizing effect that arises from the effective elasticity (the derivative of the particle pressure with respect to the void fraction): they impart to the bed. So rather than directly measure the particle pressure, we inferred the values of the elasticity from measurements of instability growth in liquid beds the inference was made by first developing a generic stability model (one with all the normally modeled coefficients left undetermined)and then working backwards to determine the unknown coefficients, including the elasticity.

  17. Reversed flow fluidized-bed combustion apparatus

    DOEpatents

    Shang, Jer-Yu; Mei, Joseph S.; Wilson, John S.

    1984-01-01

    The present invention is directed to a fluidized-bed combustion apparatus provided with a U-shaped combustion zone. A cyclone is disposed in the combustion zone for recycling solid particulate material. The combustion zone configuration and the recycling feature provide relatively long residence times and low freeboard heights to maximize combustion of combustible material, reduce nitrogen oxides, and enhance sulfur oxide reduction.

  18. Acoustic fluidization - A new geologic process

    NASA Technical Reports Server (NTRS)

    Melosh, H. J.

    1979-01-01

    A number of geologic processes, particularly seismic faulting, impact crater slumping, and long runout landslides, require the failure of geologic materials under differential stresses much smaller than expected on the basis of conventional rock mechanics. This paper proposes that the low strengths apparent in these phenomena are due to a state of 'acoustic fluidization' induced by a transient strong acoustic wave field. The strain rates possible in such a field are evaluated, and it is shown that acoustically fluidized debris behaves as a newtonian fluid with a viscosity in the range 100,000 to 10,000,000 P for plausible conditions. Energy gains and losses in the acoustic field are discussed, and the mechanism is shown to be effective if internal dissipation in the field gives a Q approximately greater than 100. Whether such values for Q are realized is not known at present. However, acoustic fluidization provides a qualitatively correct description of the failure of rock debris under low differential stresses in the processes of faulting, crater slumping, and long runout landslides. Acoustic fluidization thus deserves serious consideration as a possible explanation of these phenomena.

  19. Propagation of a fluidization - combustion wave

    SciTech Connect

    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.

  20. 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.