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Sample records for circulating fluidized bed

  1. IHI-FW circulating fluidized bed boiler

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, S.; Omata, K.; Ishimoto, R.; Asai, M. (Ishikawajima-Harima Heavy Industries, Co. Ltd., Tokyo (Japan))

    1993-07-01

    The technology and application of the circulating fluidized bed boiler (IHI-FW) are outlined. Circulating fluidized bed boilers have various features as compared with bubbling fluidized bed boilers as follows; a high combustion efficiency, efficient use of limestone for desulfurization, low NOx emission, adaptability to various fuels and capability to cope with load change. The IHI-FW boiler is furthermore featured by water-wall furnace of all-welded structure, water-cooled/steam cooled cyclone, and simple circulating system. The 30 t/h circulating fluidized bed boiler was introduced into the Tsu Works, Omikenshi Co., Ltd., Japan for private power generation. The boiler equipped with a backup heavy oil burner mainly uses semi-anthracite coal, and besides sulfur capture and NOx reduction functions of a bed, a bag filter with a high dust collecting efficiency is installed in an exhaust gas system. The installation period was reduced to 2.5 months, a half of conventional ones, by more assembly in a factory followed by less field works. 7 figs., 2 tabs.

  2. Cluster Dynamics in a Circulating Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, C.P.; Breault, R.W.

    2006-11-01

    A common hydrodynamic feature in industrial scale circulating fluidized beds is the presence of clusters. The continuous formation and destruction of clusters strongly influences particle hold-up, pressure drop, heat transfer at the wall, and mixing. In this paper fiber optic data is analyzed using discrete wavelet analysis to characterize the dynamic behavior of clusters. Five radial positions at three different axial locations under five different operating were analyzed using discrete wavelets. Results are summarized with respect to cluster size and frequency.

  3. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    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)

  4. Circulating fluidized bed boilers design and operations

    CERN Document Server

    Basu, Prabir

    1991-01-01

    This book provides practicing engineers and students with insight into the design and operation of circulating fluidized bed (CFB) boilers. Through a combination of theoretical concepts and practical experience, this book gives the reader a basic understanding of the many aspects of this subject.Important environmental considerations, including solid waste disposal and predicted emissions, are addressed individually in separate chapters. This book places an emphasis on combustion, hydrodynamics, heat transfer, and material issues, and illustrates these concepts with numerous examples of pres

  5. Modeling biomass gasification in circulating fluidized beds

    Science.gov (United States)

    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

  6. Transients in a circulating fluidized bed boiler

    Science.gov (United States)

    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.

  7. Nucla circulating atmospheric fluidized bed demonstration project

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Boiling Heat Transfer in Circulating Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    张利斌; 李修伦

    2001-01-01

    A model is proposed to predict boiling heat transfer coefficient in a three-phase circulating fluidized bed (CFB), which is a new type of evaporation boiling means for enhancing heat transfer and preventing fouling. To verify the model, experiments are conducted in a stainless steel column with 39 mm ID and 2.0 m height, in which the heat transfer coefficient is measured for different superficial velocities, steam pressures, particle concentrations and materials of particle. As the steam pressure and particle concentrations increase, the heat transfer coefficient in the bed increases. The heat transfer coefficient increases with the liquid velocity but it exhibits a local minimum.The heat transfer coefficient is correlated with cluster renewed model and two-mechanism method. The prediction of the model is in good agreement with experimental data.

  9. Boiling Heat Transfer in Circulating Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A model is proposed to predict boiling heat transfer coefficient in a three-phase circulating fluidized bed (CFB), which is a new type of evaporation boiling means for enhancing heat transfer and preventing fouling. To verify the model, experiments are conducted in a stainless steel column with 39mm ID and 2.0m height, in which the heat transfer coefficient is measured for different superficial velocities, steam pressures, particle concentrations and materials of particle. As the steam pressure and particle concentrations increase, the heat transfer coefficient in the bed increases. The heat transfer coefficient increases with the liquid velocity but it exhibits a local minimum. The heat transfer coefficient is correlated with cluster renewed model and two-mechanism method. The prediction of the model is in good agreement with experimental data.

  10. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    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)

  11. Flow boiling heat transfer in circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    Xiaoguang REN; Jiangdong ZHENG; Sefiane KHELLII; Arumemi-Ikhide MICHAEL

    2009-01-01

    In order to enhance heat transfer and mitigate contamination in the boiling processes, a new type of vapor-liquid-solid (3-phase) circulating fluidized bed boil-ing system has been designed, combining a circulating fluidized bed with boiling heat transfer. Experimental results show an enhancement of the boiling curve. Flow visualization studies concerning flow hydrodynamics within the riser column are also conducted whose results are presented and discussed.

  12. Propylene polymerization in a circulating slugging fluidized bed reactor

    NARCIS (Netherlands)

    Putten, van Inge Cornelia

    2004-01-01

    The work presented in this thesis is concerned with research on the riser of a circulating fluidized bed system for olefin polymerization. In the riser section, fluidization takes place in the transporting slugging mode and polymer particles are produced in the riser in a non-isothermal way. Propert

  13. DEVELOPMENT POTENTIALS AND RESEARCH NEEDS IN CIRCULATING FLUIDIZED BED COMBUSTION

    Institute of Scientific and Technical Information of China (English)

    Lothar Reh

    2003-01-01

    First a report about present status of circulating fluidized bed reactors for coal and multi-fuel combustion in power plants is given. Thereafter the development potentials and research needs for further improvement of CFB combustors operating with finely grained bed materials are discussed and recommendations for direction of further research and development work are presented.

  14. Characteristics of oily sludge combustion in circulating fluidized beds.

    Science.gov (United States)

    Zhou, Lingsheng; Jiang, Xiumin; Liu, Jianguo

    2009-10-15

    Incineration of oily sludge in circulating fluidized beds may be an effective way for its management in some cases. The objective of the present paper is to investigate combustion characteristics of oily sludge, which would be helpful and useful for the design and simulation of a circulating fluidized bed. Firstly, the pyrolysis and combustion of oily sludge were studied through some thermal analyses, which included the thermogravimetric (TG) analysis and the differential thermal analytical (DTA) analysis. It was found that the combustion of oily sludge might be the combustion of its pyrolysis products. Secondly, an experiment for measuring of main components of the volatile from oily sludge pyrolysis was carried out. Some mathematic correlations about the compositions of volatile from oily sludge devolatilization were achieved from the experimental results. Finally, the combustion characteristics of oily sludge was studied in a lab-scale circulating fluidized bed, which could obtain some information about the location of release and combustion of the volatiles.

  15. MODELING NONLINEAR DYNAMICS OF CIRCULATING FLUIDIZED BEDS USING NEURAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Wei; Chen; Atsushi; Tsutsumi; Haiyan; Lin; Kentaro; Otawara

    2005-01-01

    In the present work, artificial neural networks (ANNs) were proposed to model nonlinear dynamic behaviors of local voidage fluctuations induced by highly turbulent interactions between the gas and solid phases in circulating fluidized beds. The fluctuations of local voidage were measured by using an optical transmittance probe at various axial and radial positions in a circulating fluidized bed with a riser of 0.10 m in inner diameter and 10 m in height. The ANNs trained with experimental time series were applied to make short-term and long-term predictions of dynamic characteristics in the circulating fluidized bed. An early stop approach was adopted to enhance the long-term prediction capability of ANNs. The performance of the trained ANN was evaluated in terms of time-averaged characteristics, power spectra, cycle number and short-term predictability analysis of time series measured and predicted by the model.

  16. Modeling of Sulfur Retention in Circulating Fluidized Bed Coal Combustors

    Institute of Scientific and Technical Information of China (English)

    乔锐; 吕俊复; 刘青; 吴学安; 岳光溪

    2001-01-01

    A comprehensive model for predicting the sulfur retention performance in circulating fluidized bedcombustors was developed which involves the different residence times, the wide particle size distribution andthe different forms of sulfur in the coal. In addition, the reductive decomposition of CaSO4 is highlighted. Thesimulation results from the model show that the sulfur contents, the bed temperature, the sorbent particle sizedistribution and the sorbent activity or the maximum conversion rate can significantly influence the sulfuretention performance in circulating fluidized bed (CFB) combustors.``

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

  19. Single-particle behaviour in circulating fluidized beds

    DEFF Research Database (Denmark)

    Weinell, Claus Erik; Dam-Johansen, Kim; Johnsson, Jan Erik

    1997-01-01

    This paper describes an experimental investigation of single-particle behaviour in a cold pilot-scale model of a circulating fluidized bed combustor (CFBC). In the system, sand is recirculated by means of air. Pressure measurements along the riser are used to determine the suspension density...

  20. Principles of a novel multistage circulating fluidized bed reactor for biomass gasification

    NARCIS (Netherlands)

    Kersten, Sascha R.A.; Prins, Wolter; Drift, van der Bram; Swaaij, van Wim P.M.

    2003-01-01

    In this paper a novel multistage circulating fluidized bed reactor has been introduced. The riser of this multistage circulating fluidized bed consists of several segments (seven in the base-case design) in series each built-up out of two opposite cones. Due to the specific shape, a fluidized bed ar

  1. Fluidization behavior in a circulating slugging fluidized bed reactor. Part II: Plug characteristics

    NARCIS (Netherlands)

    Putten, van I.C.; Sint Annaland, van M.; Weickert, G.

    2007-01-01

    In the transporting square nosed slugging fluidization regime (0.4 < u0 < 1.0m/s) a bed of polyethylene powder with a low density (ρ = 900/kg/m3) and a large particle size distribution (70 < dρ < 1600µm) was operated in two circulating fluidized bed systems (riser diameters 0.044 and 0.105 m). A rel

  2. Circulating fluidized bed coal-saving optimization control method

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Tengfei; Li, Dewei; Xi, Yugeng; Zhou, Wu [Shanghai Jiao Tong Univ., Shanghai (China). Dept. of Automation; Ministry of Education, Shanghai (China). Key Lab. of System Control and Information Processing; Yin, Debin [Shanghai Xinhua Control Technology (Group) Co., Ltd., Shanghai (China)

    2013-07-01

    The circulating fluidized bed boiler is widely used in thermal power plants. With the proposal of energy-saving emission reduction, how to reduce coal consumption while ensure the output steam quality at the same time has become an important topic. This paper combines the technology of RTO (real-time optimization) and zone control in DMC (dynamic matrix control) to achieve this goal. The proposed method adds the coal consumption into the objective function of DMC controller and the operation point of the boiler is permitted to change within a zone which can be set according to the actual requirements of the circulating fluidized bed boiler. The zone control in DMC provides the freedom to reduce the coal consumption and achieves the economic optimal target. Compared to the simple use of constrained DMC control, the proposed method is verified to be remarkable coal-saving by the case study of a 150 t/h boiler of a power plant in Sichuan.

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  4. Combustion Model FOr Staged Circulating Fluidized Bed BOiler

    Institute of Scientific and Technical Information of China (English)

    FandJianhua; LuQinggang; 等

    1997-01-01

    A mathematical model for atmospheric staged circulating fluidized bed combustion,which takes fluid dynamics,combustion,heat transfer,pollutants formation and retention,into account was developed in the institute of Engineering Thermophysics(IET)recently.The model of gas solid flow at the bottom of the combustor was treated by the two-phase theory of fluidized bed and in the upper region as a core-annulus flow structure.The chemical species CO,CO2,H2,H2O,CH4,O2 and N2 were considered in the reaction process.The mathematical model consisted of sub-modeles of fluid namics,coal heterogeneous and gas homogeneous chemical reactions.heat transfer,particle fragmentation and attrition,mass and energy balance tec.The developed code was applied to simulate an operating staged circulating fluidized bed combustion boiler of early design and the results were in good agreement with the operating data.The main submodels and simulation results are given in this paoper.

  5. Characterization of fluidization regime in circulating fluidized bed reactor with high solid particle concentration using computational fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chalermsinsuwan, Benjapon; Thummakul, Theeranan; Piumsomboon, Pornpote [Chulalongkorn University, Bangkok (Thailand); Gidaspow, Dimitri [Armour College of Engineering, Chicago (United States)

    2014-02-15

    The hydrodynamics inside a high solid particle concentration circulating fluidized bed reactor was investigated using computational fluid dynamics simulation. Compared to a low solid particle reactor, all the conventional fluidization regimes were observed. In addition, two unconventional fluidization regimes, circulating-turbulent and dense suspension bypassing regimes, were found with only primary gas injection. The circulating-turbulent fluidization regime showed uniformly dense solid particle distribution in all the system directions, while the dense suspension bypassing fluidization regime exhibited the flow of solid particles at only one side system wall. Then, comprehensive fluidization regime clarification and mapping were evaluated using in-depth system parameters. In the circulating-turbulent fluidization regime, the total granular temperature was low compared to the adjacent fluidization regimes. In the dense suspension bypassing fluidization regime, the highest total granular temperature was obtained. The circulating-turbulent and dense suspension bypassing fluidization regimes are suitable for sorption and transportation applications, respectively.

  6. Control of the Bed Temperature of a Circulating Fluidized Bed Boiler by using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    AYGUN, H.

    2012-05-01

    Full Text Available Circulating fluidized bed boilers are increasingly used in the power generation due to their higher combustion efficiency and lower pollutant emissions. Such boilers require an effective control of the bed temperature, because it influences the boiler combustion efficiency and the rate of harmful emissions. A Particle-Swarm-Optimization-Proportional-Integrative-Derivative (PSO-PID controller for the bed temperature of a circulating fluidized bed boiler is presented. In order to prove the capability of the proposed controller, its performances are compared at different boiler loads with those of a Fuzzy Logic (FL controller. The simulation results demonstrate some advantages of the proposed controller.

  7. Gasification of sawdust in pressurised internally circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Maartensson, R.; Lindblom, M. [Lund Univ. (Sweden). Dept. of Chemical Engineering

    1996-12-31

    A test plant for pressurised gasification of biofuels in a internally circulating fluidized bed has been built at the department of Chemical Engineering II at the University of Lund. The design performance is set to maximum 20 bar and 1 050 deg C at a thermal input of 100 kW or a maximum fuel input of 18 kg/in. The primary task is to study pressurised gasification of biofuels in relation to process requirements of the IGCC concept (integrated gasification combined cycle processes), which includes studies in different areas of hot gas clean-up in reducing atmosphere for gas turbine applications. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  9. Detachment of multi species biofilm in circulating fluidized bed bioreactor.

    Science.gov (United States)

    Patel, Ajay; Nakhla, George; Zhu, Jingxu

    2005-11-20

    In this study, the detachment rates of various microbial species from the aerobic and anoxic biofilms in a circulating fluidized bed bioreactor (CFBB) with two entirely separate aerobic and anoxic beds were investigated. Overall detachment rate coefficients for biomass, determined on the basis of volatile suspended solids (VSS), glucose and protein as well as for specific microbial groups, i.e., for nitrifiers, denitrifiers, and phosphorous accumulating organisms (PAOs), were established. Biomass detachment rates were found to increase with biomass attachment on carrier media in both beds. The detachment rate coefficients based on VSS were significantly affected by shear stress, whereas for protein, glucose and specific microbial groups, no significant effect of shear stress was observed. High detachment rates were observed for the more porous biofilm structure. The presence of nitrifiers in the anoxic biofilm and denitrifiers in the aerobic biofilm was established by the specific activity measurements. Detachment rates of PAOs in aerobic and anoxic biofilms were evaluated.

  10. Cold-Flow Circulating Fluidized-Bed Identification

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Circulating fluidized bed biological reactor for nutrients removal

    Institute of Scientific and Technical Information of China (English)

    Yubo CUI; Hongbo LIU; Chunxue BAI

    2008-01-01

    A new biological nitrogen removal process, which is named herein "The circulating fluidized bed bio-reactor (CFBBR)", was developed for simultaneous removal of nitrogen and organic matter. This process was composed of an anaerobic bed (Riser), aerobic bed (Downer) and connecting device. Influent and nitrified liquid from the aerobic bed enters the anaerobic bed from the bottom of the anaerobic bed, completing the removal of nitrogen and organic matter. The system performance under the conditions of different inflow loadings and nitrified liquid recirculation rates ranging from 200% to 600% was examined. From a technical and economic point of view, the optimum nitrified liquid recirculation rate was 400%. With a shortest total retention time of 2.5 h (0.8 h in the anaerobic bed and 1.5 h in the aerobic bed) and a nitrified liquid recir-culation rate of 400% based on the intluent flow rate, the average removal efficiencies of total nitrogen (TN) and sol-uble chemical oxygen demand (SCOD) were found to be 88% and 95%, respectively. The average effluent concentra-tions of TN and SCOD were 3.5 mg/L and 16 mg/L, respectively. The volatile suspended solid (VSS) concentra-tion, nitrification rate and denitrification rate in the system were less than 1.0 g/L, 0.026-0.1 g NH4+-N/g VSS.d, and 0.016-0.074 g NOx--N/g VSS.d, respectively.

  12. Linear system identification of a cold flow circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Panday, R [West Virginia Univ., Morgantown, WV (United States); Woerner, B D [West Virginia Univ., Morgantown, WV (United States); Ludlow, J C [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Shadle, L J [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Boyle, E J [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2009-02-01

    Knowledge of the solids circulation rate (SCR) is essential to the control and improved performance of a circulating fluidized bed system. In the present work, the noise model is derived using the prediction error method considering process and measurement noises acting on the cold flow circulating fluidized bed (CFCFB) with a cork particulate material. The outputs of the initial model are the total pressure drop across the riser, the pressure drop across the crossover, the pressure drop across the primary cyclone, the total pressure drop across the stand-pipe, the pressure drop across the loop seal, and the SCR. The stochastic estimate of SCR is determined from the noise model using the stochastic pressure drop estimates. The deterministic estimate is obtained through the inputs taken as move air flow, riser aeration, and loop seal fluidization air that are all independent variables of the given setup and under the control of the user. The theory has been developed to convert a complete blackbox model to a grey box model through the output-to-state transformation such that both the models of the CFCFB consists of all these output variables as the states of the system, and only pressure drops across the system as the output measurements. Thus, the final models do not include any fictitious terms and they are defined only in terms of physical parameters of the given system. Both components of SCR are separately analysed. The combined SCR response of both the noise model and deterministic model is compared with the validation data set of this state variable in terms of modelfit, and the results are shown.

  13. Internal circulating fluidized bed incineration system and design algorithm.

    Science.gov (United States)

    Tian, W D; Wei, X L; Li, J; Sheng, H Z

    2001-04-01

    The internal circulating fluidized bed (ICFB) system is characterized with fast combustion, low emission, uniformity of bed temperature and controllability of combustion process. It is a kind of novel clean combustion system, especially for the low-grade fuels, such as municipal solid waste (MSW). The experimental systems of ICFB with and without combustion were designed and set up in this paper. A series of experiments were carried out for further understanding combustion process and characteristics of several design parameters for MSW. Based on the results, a design routine for the ICFB system was suggested for the calculation of energy balance, airflow rate, heat transfer rate, and geometry arrangement. A test system with ICFB combustor has been set up and the test results show that the design of the ICFB system is successful.

  14. Internal circulating fluidized bed system and design algorithm

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The internal circulating fluidized bed (ICFB) system ischaracterized with fast combustion, low emission, uniformity of bed temperature and controllability of combustion process. It is a kind of novel clean combustion system, especially for the low-grade fuels, such as municipal solid waste(MSW). The experimental systems of ICFB with and without combustion were designed and set up in this paper. A series of experiments were carried out for further understanding combustion process and characteristics of several design parameters for MSW. Based on the results, a design routine for the ICFB system was suggested for the calculation of energy balance, airflow rate, heat transfer rate, and geometry arrangement. A test system with ICFB combustor has been set up and the test results show that the design of the ICFB system issuccessful.

  15. Heat flux distribution on circulating fluidized bed boiler water wall

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The future of circulating fluidized bed (CFB)combustion technology is in raising the steam parameters to supercritical levels.Understanding the heat flux distribution on the water wall is one of the most important issues in the design and operation of supercritical pressure CFB boilers.In the present paper,the finite element analysis (FEA) method is adopted to predict the heat transfer coefficient as well as the heat flux of the membrane wall and the results are validated by direct measurement of the temperature around the tube.Studies on the horizontal heat flux distribution were conducted in three CFB boilers with different furnace size,tube dimension and water temperature.The results are useful in supercritical pressure CFB boiler design.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Kosowska-Golachowska Monika

    2016-03-01

    Full Text Available 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.

  18. Design and simulation of a circulating fluidized bed to clean the products of biomass gasification

    Energy Technology Data Exchange (ETDEWEB)

    Uchoa Neto, Moises; Carvalho, Yuri de Araujo [Dept. de Engenharia Mecanica. Faculdade de Tecnologia. Universidade de Brasilia, DF (Brazil); Oliveira, Taygoara Felamingo de; Barcelos, Manuel [Faculdade do Gama. Universidade de Brasilia, Gama, DF (Brazil)], e-mail: taygoara@unb.br

    2010-07-01

    The main goal of this work is to design a workbench circulating fluidized bed to study the cracking of tar in gases from the processes of biomass gasification. For this, a design methodology based on analytical results and empirical correlations for fluidized beds was employed. In parallel, a numerical code of open source technology (MFIX) for the solution of the transport equations of the multiphase flow in the column of a fluidized bed was used to give support to the choice of the design elements. The whole project of the workbench fluidized bed was completely developed, whose operation parameters such as bed geometry, gas velocity, circulating ratio and void fraction characterize a fast fluidization process. A preliminary mesh convergence study was executed with the numerical tool, that was validated comparing with analytical results. Among the most important results, the code computed the predicted value for the minimum fluidization. (author)

  19. Pneumatic jet-control valve for dual circulating fluidized beds

    Science.gov (United States)

    Jiang, Haibo; Dong, Pengfei; Zhu, Zhiping; Wang, Kun; Zhang, Yukui; Lu, Qinggang

    2015-11-01

    With the rapid development of circulating fluidized bed (CFB) technology in different fields, the disadvantages of conventional non-mechanical valves are becoming more apparent, and they are not suitable to be used in complex CFB systems. In this paper, a novel non-mechanical valve named the jet-control valve is presented which can avoid the fluidization of solid particles. The feasibility and performance characteristics of the new valve are investigated with a cold-model dual CFB. The results show that compared with the conventional non-mechanical valve, the jet-control valve can transfer solid particles steadily over a larger range, prevent artesian flow, and improve the leakage characteristics. The effects of the operating parameters and structural parameters on the minimum aeration velocity, solid flow rate, and maximum solid flow rate are studied. A two-valve model is proposed to explain the transport capacity of the valve for one jet pipe. A semi-theoretical expression is obtained based on the experimental data with a maximum deviation of 30% providing useful guide for scaling-up the design.

  20. Olive cake combustion in a circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Topal, H.; Durmaz, A. [Gazi Univ, Ankara (Turkey). Dept. of Mechanical Engineering; Atimtay, A.T. [Middle East Technical Univ., Ankara (Turkey). Dept. of Environmental Engineering

    2002-07-01

    This paper presents the results of a study in which an environmentally sound technology was developed for biomass usage for energy production in Turkey. A circulating fluidized bed of 125 mm diameter and 1,800 mm height was used to determine the combustion characteristics of olive cake (OC) produced in Turkey. Olive cake, an olive oil milling waste product, is available in large amounts at a very low cost. Efficient use of OC in energy production solves the problem of waste management and contributes to meeting targets of the Kyoto Protocol. In this study, olive cake alone and olive cake plus lignite mixtures were burned in separate experiments and in various ratios. A new feeding mechanism was developed to feed the olive cake to the bed. On-line concentrations of oxygen, sulphur dioxide, carbon dioxide, carbon monoxide, nitrogen oxides and total hydrocarbons were measured in the flue gas along with temperature distribution in the bed. Emissions were compared with national standards and combustion efficiency of the olive cake plus lignite coal mixtures and olive cake alone were calculated. The optimum operating parameters were described. OC burned with 94 to 98.5 per cent efficiency. The combustion efficiency increased with increased excess air ratio because volatiles released from the fuel were burned more completely. 3 refs., 5 tabs., 6 figs.

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

    Science.gov (United States)

    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.

  2. Attempts on cardoon gasification in two different circulating fluidized beds

    Directory of Open Access Journals (Sweden)

    Chr. Christodoulou

    2014-11-01

    Full Text Available Few tests have been carried out in order to evaluate the use of cardoon in gasification and combustion applications most of the researchers dealt with agglomeration problems. The aim of this work is to deal with the agglomeration problem and to present a solution for the utilization of this biofuel at a near industrial application scale. For this reason, two experiments were conducted, one in TU Delft and one in Centre for Research and Technology Hellas (CERTH, using fuel cardoon and 50% w/w cardoon blended with 50% w/w giant reed respectively. Both experimental campaigns were carried out in similar atmospheric circulating fluidized bed gasifiers. Apart from the feedstock, the other differences were the gasification medium and the bed material used in each trial. The oxidizing agent at TUD׳s run was O2/steam, whereas CERTH׳s tests used air. When experiments with the cardoon 50% w/w–giant reed 50% w/w blend were performed no agglomeration problems were presented. Consequently, gasification could be achieved in higher temperature than that of pure cardoon which led to the reduction of tar concentration.

  3. INVESTIGATION INTO MALDISTRIBUTION IN A CIRCULATING FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    Qingjie Guo; Joachim Werther; Ernst-Ulrich Hartge

    2003-01-01

    Experiments on maldistribution were conducted in a 8.5 m high, 1 m ×0.3 m cross-section circulating fluidized bed equipped with a 33 bubble-cap distributor. There exists an uneven distribution in flow rate, the bubble caps in the center region having larger flow rates than those next to the wall. Flow resistance has been found to be the dominating factor influencing gas flow rate distribution. Increasing superficial gas velocity improves flow rate distribution for a low pressure-drop distributor. For a high pressure-drop distributor, superficial gas velocity has little effect on flow rate distribution. A ratio of maximum flow rate through a bubble cap to average flow rate through all bubble caps (Vmax/Vav) characterizes the flow rate distribution. Distributor-to-bed pressure drop ratio (△Pd/△Pr) is another necessary parameter to achieve even flow distribution. A correlation between these two ratios is developed for predicting flow rate maldi stribution in CFB bubble-cap distributor.

  4. Gasification process of refuse derived fuel in circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Ichikawa, S.; Kinoshita, Y.; Lee, C.W.; Itaya, Y.; Mori, S. [Nagoya Univ., Nagoya (Japan). Dept. of Chemical Engineering

    2002-07-01

    This paper presents a fuel gas production system involving gasification of refuse-derived fuel (RDF) in a circulating fluidized bed (CFB). Although RDF is considered to be a viable source of energy, combustion of RDF has not spread widely because of a lack of conventional incinerators, erosion due to hydrogen chloride, and emissions of dioxin. This paper presents the results of an experimental study of the pyrolysis behaviour of 3 kinds of RDF and the particle motion in a cold model CFB. The objective was to clarify operating parameters for optimum control. It was shown that an increase in combustion temperature improves the yield of the combustible gas components and the energy recycling efficiency from the RDF. The highest heating value of pyrolysis gas was obtained at 873 to 973 degrees K. The gas flow rate in the pneumatic valve of the CFB was an important control factor for the circulation flux and solids holdup in the riser. High holdups were observed when minute silica sand particles were used in the CFB. 15 refs., 1 tab., 8 figs.

  5. Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars-Erik; Dam-Johansen, Kim;

    1996-01-01

    The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O in the comb......The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O...

  6. Ash behavior and de-fluidization in low temperature circulating fluidized bed biomass gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas

    -Temperature Circulating Fluidized Bed System (LTCFB) gasifier allows pyrolysis and gasification of biomass to occur at low temperatures thereby improving the retention of alkali and other ash species within the system and minimizing the amount of ash species in the product gas. In addition, the low reactor temperature......Biomass is increasingly used as a fuel for power generation. Herbaceous fuels however, contain high amounts of alkali metals which get volatilized at high temperatures and forms salts with low melting points and thus condense on pipelines, reactor surfaces and may cause de-fluidization. A Low...... at Risø and a 6 MW LTCFB gasifier owned by DONG ENERGY and placed in Kalundborg. In addition to the analysis of the inorganic elemental composition of the collected samples, SEM and TGA analysis of the samples were made to improve understanding on the behavior of the ash forming species within the system...

  7. Olive cake combustion in a circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Huseyin Topal; Aysel T. Atimtay; Ali Durmaz [Gazi University, Ankara (Turkey). Department of Mechanical Engineering, Engineering and Architecture Faculty

    2003-06-01

    In this study, a circulating fluidized bed of 125 mm diameter and 1800 mm height was used to find the combustion characteristics of olive cake (OC) produced in Turkey. A lignite coal that is most widely used in Turkey was also burned in the same combustor. The combustion experiments were carried out with various excess air ratios. The excess air ratio, {lambda} has been changed between 1.1 and 2.16. Temperature distribution along the bed was measured with thermocouples. On-line concentrations of O{sub 2}, SO{sub 2}, CO{sub 2}, CO, NOx and total hydrocarbons were measured in the flue gas. Combustion efficiencies of OC and lignite coal are calculated, and the optimum conditions for operating parameters are discussed. The combustion efficiency of OC changes between 82.25 and 98.66% depending on the excess air ratio. There is a sharp decrease observed in the combustion losses due to hydrocarbons and CO as the excess air ratio increases. The minimum emissions are observed at {lambda} = 1.35. Combustion losses due to unburned carbon in the bed material do not exceed 1.4 wt% for OC and 1.85 wt% for coal. The combustion efficiency for coal changes between 82.25 and 98.66% for various excess air ratios used in the study. The ash analysis for OC is carried out to find the suitability of OC ash to be used as fertilizer. The ash does not contain any hazardous metal. 7 refs., 10 figs., 6 tabs.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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.

  10. Modeling of sulfur oxide removal in circulating fluidized bed absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Mao, D.; Edwards, J.R.; Kuznetsov, A.V. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Mechanical and Aerospace Engineering; Srivastava, R. [U.S. Environmental Protection Agency, Research Triangle Park, NC (United States). Air Pollution Prevention and Control Division

    2002-07-01

    This paper presents a model to simulate a circulating fluidized bed absorber (CFBA) that combines flow, mixing, and reaction through residence time distribution (RTD). These parameters are often overlooked in existing simulation models. In addition, the paper presents a newly developed gas-solid reaction model for sulphur dioxide removal by limestone. For the reaction model that considers RTD inside the core and annulus regions of CFBA, the macrochemical reaction is simulated according to microchemical reaction dynamics. The proposed model can predict sulphur dioxide and limestone distributions inside the CFBA and calculate how much limestone is needed to remove an appropriate amount of sulphur dioxide. Sulphur dioxide concentration at the outlet of the CFBA decreases as the distance of the CFBA increases from the bottom of the core region. Limestone concentration varies only very slightly in the core region, suggesting that limestone in the CFBA is efficiently utilized to remove sulphur oxide. Sulphur dioxide partial pressure at the exit of the CFBA decreases as fresh limestone increases at the inlet to the CFBA. 16 refs., 8 figs.

  11. RADIAL PROFILE OF THE SOLID FRACTION IN A LIQUID-SOLID CIRCULATING FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    Tiefeng Wang; Jinfu Wang; Jing Lin; Yong Jin

    2003-01-01

    @@ Liquid-solid circulating fluidized beds have a number of attractive features suitable for processes where liquid-solid contact is important (Liang et al., 1996; Zhang et al., 2002).Liang et al. (1996) and Zheng et al. (2002) studied the radial profile of the solid fraction in the liquid-solid circulating fluidization regime and found that it is not uniform, unlike the conventional liquid-solid fluidized bed. This non-uniformity can affect reactant concentration distribution, mass transfer and ultimately reactant conversion.Therefore, information on the radial flow structure is crucial to reactor design and process optimization.

  12. Comprehensive Mathematical Model for Coal Combustion in a Circulating Fluidized Bed Combustor

    Institute of Scientific and Technical Information of China (English)

    金晓钟; 吕俊复; 杨海瑞; 刘青; 岳光溪; 冯俊凯

    2001-01-01

    Char combustion is on a special reducing condition in the dense bed of a circulating fluidized bedcombustor. Experimental findings were used to develop a comprehensive mathematical model to simulate thehydrodynamic and combustion processes in a circulating fluidized bed combustor. In the model, gas-solidinteraction was used to account for the mass transfer between the bubble phase and the emulsion phase in thedense bed, which contributes to the reducing atmosphere in the dense bed. A core-annular structure wasassumed in the dilute area rather than a one-dimensional model. The submodels were combined to build thecomprehensive model to analyze the combustion in a circulating fluidized bed combustor and the effect ofoperating parameters on the coal combustion. The model predictions agree well with experimental results.

  13. Holdup and Flow Behavior of Fluidized Solid Particles in a Liquid-Solid Circulating Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Dae Ho; Lim, Ho; Jin, Hae Ryong; Kang, Yong [Chungnam National University, Daejeon (Korea, Republic of)

    2014-06-15

    Characteristics of holdup and flow behavior of fluidized solid particles were investigated in a liquid-solid circulating fluidized bed (0.102 m x 3.5 m). Effects of liquid velocity (U{sub L}), particle size (d{sub P}) and solid circulation rate (G{sub S}) on the solid holdup, overall particle rising velocity, slip velocity between liquid and particles and hydrodynamic energy dissipation rate in the riser were examined. The particle holdup increased with increasing d{sub P} or G{sub S} but decreased with increasing U{sub L}. The overall particle rising velocity increased with increasing U{sub L} or G{sub S} but decreased with increasing d{sub P}. The slip velocity increased with increasing U{sub L} or d{sub P} but did not change considerably with G{sub S}. The energy dissipation rate, which was found to be closely related to the contacting frequency of micro eddies, increased with increasing d{sub P}, G{sub S} or U{sub L}. The solid particle holdup was well correlated with operating variables such as U{sub L}, d{sub P} and G{sub S}.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. Multi-stage circulating fluidized bed syngas cooling

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. [Radiation transformation mechanism in a photocatalytic reactor of three-phase internal circulating fluidized bed].

    Science.gov (United States)

    You, Hong; Luo, Wei-nan; Yao, Jie; Chen, Ping; Cai, Wei-min

    2005-01-01

    A novel three-phase internal circulating fluidized bed photocatalytic reactor was established and the radiation transformation in which was investigated. The experimental results indicate that with the interaction of gas and solid (gas flux > 0.3m3/h), the radiation transformation in the reactor along radial direction conforms to a definite exponential function, which agrees to formula Rose about the rules of light intensity distribution through evenly suspended particles. The value of radiation energy is affected by the initial light intensity, the concentration of photocatalyst and the thickness of liquid layer. The aerated gas amount only influence the state of the fluidized bed and has little effect on the distribution of light intensity along radical direction. Photocatalytic degradation of Rhodamine B indicate that the efficiency of three-phase internal circulating fluidized bed is much higher than slurry bed. The optimal catalyst concentration of this system is 10 - 12g/L.

  18. Hydrodynamics of a hybrid circulating fluidized bed reactor with a partitioned loop seal system

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Dal-Hee; Moon, Jong-Ho; Jin, Gyoung Tae; Shun, Dowon [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Yun, Minyoung; Park, Chan Seung; Norbeck, Joseph M. [University of California, Riverside (United States)

    2015-07-15

    A circulating fluidized bed (CFB) with a hybrid design has been developed and optimized for steam hydrogasification. The hybrid CFB is composed of a bubbling fluidized bed (BFB) type combustor and a fast fluidized bed (FB) type gasifier. Char is burnt in the combustor and the generated heat is supplied to the gasifier along with the bed materials. Two different types of fluidized beds are connected to each other with a newly developed partitioned loop seal to avoid direct contact between two separate gas streams flowing in each fluidized bed. Gas mixing tests were carried out with Air and Argon in a cold model hybrid CFB to test the loop seal efficiency. Increase in solid inventory in the loop seal can improve the gas separation efficiency. It can be realized at higher gas velocity in fast bed and with higher solid inventory in the loop seal system. In addition, bed hydrodynamics was investigated with varying gas flow conditions and particle sizes in order to obtain a full understanding of changes of solid holdup in the FB. The solid holdup in the FB increased with increasing gas velocity in the BFB. Conversely, increase in gas velocity in the FB contributed to reducing the solid holdup in the FB. It was observed that changing the particle size of bed material does not have a big impact on hydrodynamic parameters.

  19. STUDY ON THE OVERALL PRESSURE BALANCE OF A DOWNFLOW CIRCULATING FLUIDIZED BED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Hengzhi Chen; Dawei Yang; Hongzhong Li; Shiyu Tan

    2006-01-01

    A pressure balance model for a circulating fluidized bed unit that incorporates a downer has been proposed. The model predictions were validated with the experimental data obtained from a special cold-model circulating fluidized bed. Comparison of the operation stability between a CFB downer and a CFB riser has been carried out. Only one critical gas velocity exists in the CFB-riser for a given riser solids flux, while there can be many critical gas velocities for the operation of a CFB downer. Therefore, it is possible to achieve high solids concentration in a CFB downer if appropriate operating conditions are used.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Experimental Study on an On-Line Measurement of High Temperature Circulating Ash Flux in a Circulating Fluidized Bed Boiler

    Institute of Scientific and Technical Information of China (English)

    Lu Xiaofeng; Li Yourong

    2001-01-01

    A new kind of measuring method that may be used to measure high temperature circulating solid particles flux in a circulating fluidized bed boiler is studied in this paper. The measuring method is founded on the principle of thermal equilibrium. A series of cold tests and hot tests were carried to optimize the structure and collocation of water-cooling tubes and showed that the method had the advantage of simple, accurate, reliable and good applicability for on-line usage in a circulating fluidized bed boiler.

  2. MULTIFRACTAL ANALYSIS OF PARTICLE-FLUID SYSTEM IN A CIRCULATING FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    Liping; Ma; Weixing; Huang; Yanfu; Shi; Huarui; Yu; Jingxu; Zhu

    2005-01-01

    In this paper, multifractal analysis together with wavelet transform modulus maxima (WTMM) method is used to analyze the fluctuating signals of circulating fluidized bed (CFB). Singularity spectrum shows that the gas-particle flow in CFB has multifractal character. Motion behavior of the particle-fluid system of CFB can be described by singularity spectrum. Intermittency index can be used to determine the transition of flow regime from fast fluidization to pneumatic conveying.

  3. A study on Heat Transfer for Immersed Tube in Internally Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    TianWendong; HaoJinhua; 等

    1999-01-01

    Heat transfer coefficients for horizontally immersed tubes have been studied in a model of ICFB(Inter-nally Circulating Fluidized Bed).The characteristics in ICFB were found to be significantly different from those in bubbing bed.There is a flowing zone with high velocity in the heat exchange zone.The heat transfer coefficients strongly depend on the fluidized velocity in the flowing zone.The heat exchange process and suitable bed temperature can be controlled according to this feature.Based on the results of the experiments,a formulation for heat transfer has been developed.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    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...

  7. Continuous CO2 capture in a circulating fluidized bed using supported amine sorbents

    NARCIS (Netherlands)

    Veneman, R.; Li, Z.; Hogendoorn, J.A.; Kersten, S.R.A.; Brilman, D.W.F.

    2012-01-01

    In this work, supported amine sorbents were prepared by physical impregnation of silica and polymethylmethacrylate (PMMA) with tetraethylenepentamine (TEPA) and studied for post-combustion CO2 capture purposes in a lab scale circulating fluidized bed (CFB) reactor. Sorbent amine loading and support

  8. A small scale regularly packed circulating fluidized bed. Part I: Hydrodynamics.

    NARCIS (Netherlands)

    Ham, van der A.G.J.; Prins, W.; Swaaij, van W.P.M.

    1994-01-01

    The present investigation is based on the idea of intensifying the gas¿solids contact in a circulating fluidized bed by introducing obstacles into it. Such obstacles may effectively suppress radial inhomogeneities in the solids flux and concentration, increase the dynamic solids hold-up, and break u

  9. Laser Doppler anemometry measurements in a circulating fluidized bed of metal particles

    DEFF Research Database (Denmark)

    Ibsen, Claus Hübbe; Solberg, Tron; Hjertager, Bjørn Helge;

    2002-01-01

    Laser Doppler Anemometry (LDA) measurements were performed in a 1/9 scale model of a 12 MW circulating fluidized bed (CFB) boiler. The model was operated according to scaling laws. The 2D-LDA system used was positioned in two different ways to obtain the three velocity components u, v and w...

  10. Bed-inventory Overturn Mechanism for Pant-leg Circulating Fluidized Bed Boilers

    CERN Document Server

    Wang, Zhe; Yang, Zhiwei; West, Logan; Li, Zheng

    2011-01-01

    A numerical model was established to investigate the lateral mass transfer as well as the mechanism of bed-inventory overturn inside a pant-leg circulating fluidized bed (CFB), which are of great importance to maintain safe and efficient operation of the CFB. Results show that the special flow structure in which the solid particle volume fraction along the central line of the pant-leg CFB is relative high enlarges the lateral mass transfer rate and make it more possible for bed inventory overturn. Although the lateral pressure difference generated from lateral mass transfer inhibits continuing lateral mass transfer, providing the pant-leg CFB with self-balancing ability to some extent, the primary flow rate change due to the outlet pressure change often disable the self-balancing ability by continually enhancing the flow rate difference. As the flow rate of the primary air fan is more sensitive to its outlet pressure, it is easier to lead to bed inventory overturn. While when the solid particle is easier to c...

  11. The Study of Dynamic Processes in the Boiler Furnace with Circulating Fluidized Bed

    OpenAIRE

    Gil A. V.; Baturin D. A.

    2016-01-01

    The paper presents a numerical simulation of the furnace with a circulating fluidized bed. Numerical study carried out on all volume of the combustion chamber. The results contours of particulate matter concentration and of velocities, as well as a graphical representation of changes in the concentration of particles on the bed height are shown. Simulation performed in Eulerian - Eulerian and Lagrange representation on a 3D model.

  12. The Study of Dynamic Processes in the Boiler Furnace with Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Gil A. V.

    2016-01-01

    Full Text Available The paper presents a numerical simulation of the furnace with a circulating fluidized bed. Numerical study carried out on all volume of the combustion chamber. The results contours of particulate matter concentration and of velocities, as well as a graphical representation of changes in the concentration of particles on the bed height are shown. Simulation performed in Eulerian - Eulerian and Lagrange representation on a 3D model.

  13. Modeling Study of a New Circulating Fluidized Bi—Bed Boiler Combustion System

    Institute of Scientific and Technical Information of China (English)

    ZhaoJian; SuoYisheng; 等

    1999-01-01

    This paper presents a set of general dynamic mathematical models for the combustion system of a circulating fluidized bi-bed boiler,The models fully consider the flow.combustion and heat transfer characteristics,and describe the physical and chemical processes inside the bi-bed,including the gassolid flow.multiple particles combustion,gas chemical reactions,heat transfer and pressure balances.etc.

  14. Spectral analysis of CFB data: Predictive models of Circulating Fluidized Bed combustors

    Energy Technology Data Exchange (ETDEWEB)

    Gamwo, I.K.; Miller, A.; Gidaspow, D.

    1992-04-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Spectral analysis of CFB data obtained at Illinois Institute of Technology shows that the frequencies of pressure oscillations are less than 0.1 Hertz and that they increase with solids volume fraction to the usual value of one Hertz obtained in bubbling beds. These data are consistent with the kinetic theory interpretation of density wave propagation.

  15. Axial Liquid Dispersion in Gas-Liquid-Solid Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    M.Vatanakul; 孙国刚; 郑莹; M.Couturier

    2005-01-01

    The effects of liquid viscosities, solid circulating rates, liquid and gas velocities and phase holdups on the axial dispersion coefficient, Dax, were investigated in a gas-liquid-solid circulating fluidized bed (GLSCFB).Liquid viscosity promotes the axial liquid backmixing when solid particles and gas bubbles are present. Increases in gas velocities and solid circulating rates lead to higher Dax. The effects of liquid velocity on Dax are associated with liquid viscosity. Compared with conventional expanded beds, the GLSCFBs hold less axial liquid dispersion,approaching ideal plug-flow reactors.

  16. A Mathematical Model for Differential—Velocity Circulating Fluidized Bed Boiler

    Institute of Scientific and Technical Information of China (English)

    LiZhao; XiangdongXu

    1999-01-01

    The scheme of differential-velocity circulating fluidized bed was put forward by Thermal Engineering Department of Tsinghua university in 1992 and got patent simultaneously.An internal bed material circulation in combustor can be established by the discrepancy of entrainment at different air velocity,and separates the combustor into three different velocity regions,which constitutes the differential-velocity inside circulation.Mathematical modeling and simulation may facilitate understanding,Development and operation of this new process.Here cell model method was adopted to set up the model.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  19. Development of pressurized internally circulating fluidized bed combustion technology; Kaatsu naibu junkan ryudosho boiler no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, I. [Center for Coal Utilization, Japan, Tokyo (Japan); Nagato, S.; Toyoda, S. [Ebara Corp., Tokyo (Japan)

    1996-09-01

    The paper introduced support research on element technology needed for the design of hot models of the pressurized internally circulating fluidized bed combustion boiler in fiscal 1995 and specifications for testing facilities of 4MWt hot models after finishing the basic plan. The support research was conduced as follows: (a) In the test for analysis of cold model fluidization, it was confirmed that each characteristic value of hot models is higher than the target value. Further, calculation parameters required for computer simulation were measured and data on the design of air diffusion nozzle for 1 chamber wind box were sampled. (b) In the CWP conveyance characteristic survey, it was confirmed that it is possible to produce CWP having favorable properties. It was also confirmed that favorable conveyability can be maintained even if the piping size was reduced down to 25A. (c) In the gas pressure reducing test, basic data required for the design of gas pressure reducing equipment were sampled. Specifications for the fluidized bed combustion boiler of hot models are as follows: evaporation amount: 3070kg/h, steam pressure: 1.77MPa, fuel supply amount: 600kg-coal/h, boiler body: cylinder shape water tube internally circulating fluidized bed combustion boiler. 4 refs., 4 figs.

  20. Behavior of Alkali Metals and Ash in a Low-Temperature Circulating Fluidized Bed (LTCFB) Gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas; Jensen, Peter Arendt; Henriksen, Ulrik Birk

    2016-01-01

    A low-temperature circulating fluidized bed system (LTCFB) gasifier allows for pyrolysis and gasification to occurat low temperatures, thereby improving the retention of alkali and other inorganic elements within the system and minimizingthe amount of ash species in the product gas. In addition......, the low reactor temperature ensures that high-alkali biomass fuels canbe used without risk of bed defluidization. This paper presents the first investigation of the fate of alkali metals and ash in lowtemperaturegasifiers. Measurements on bed material and product gas dust samples were made on a 100 k...

  1. Flow Field of Circulating Fluidized Bed Reactor with Venturi Inlet Configuration

    Institute of Scientific and Technical Information of China (English)

    HU Jinbang; LI Yanping; CHEN Anxin

    2005-01-01

    Different two-equation k-ε models were used to simulate the gas flow field generated by a new type of circulating fluidized bed reactor with venturi gas distributor. The numerical results were compared with the experimental data. It has been shown that the simulation results from the standard k-ε model have the best match with the experimental data. Based on this model, the gas flow field in the venturi diffuser and riser was analyzed by the concept of velocity nonuniformity and dead zone percentage. Both the nonuniformity of gas velocity and the dead zone percentage reach the maximum at the venturi outlet due to the effect of the vortex. At the same time, it provides a good platform for the further optimization of the inlet configuration of circulating fluidized bed reactor.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Research of integral parameters for furnaces of a circulating fluidized bed

    Science.gov (United States)

    Gil, Andrey V.; Gil, Alexandra Y.

    2015-01-01

    Modern society poses several energy problems. Improving the efficiency and reliability of power equipment and reduce the impact on the environment. The paper presents the promising technology of superheated steam using different coals. The model of the furnace with a circulating fluidized bed and numerical simulation results of gas dynamic processes using application FIRE 3D. The analysis of aerodynamics and the distribution of the dispersed phase adjustment of the furnace.

  4. Research of integral parameters for furnaces of a circulating fluidized bed

    Directory of Open Access Journals (Sweden)

    Gil Andrey V.

    2015-01-01

    Full Text Available Modern society poses several energy problems. Improving the efficiency and reliability of power equipment and reduce the impact on the environment. The paper presents the promising technology of superheated steam using different coals. The model of the furnace with a circulating fluidized bed and numerical simulation results of gas dynamic processes using application FIRE 3D. The analysis of aerodynamics and the distribution of the dispersed phase adjustment of the furnace.

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

    Science.gov (United States)

    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.

  6. SOLID HOLDUP AND CIRCULATION RATE IN A LIQUID-SOLID CIRCULATING FLUIDIZED BED WITH VISCOUS LIQUID MEDIUM

    Directory of Open Access Journals (Sweden)

    N. Gnanasundaram

    2015-12-01

    Full Text Available Abstract Experiments were conducted in a liquid-solid circulating fluidized bed with different viscous liquids and particles to study the hydrodynamics, average solid hold up and solid circulation rate. The effects of operating parameters, i.e., primary liquid flow rate in the riser, auxiliary liquid flow rate, total liquid flow rate and viscosity of the liquid were studied for solids of different density and particle size. Results show that the circulating fluidization regime starts earlier for more viscous solutions because of the decrease in critical transitional velocity. The onset of solid holdup increases with an increase in liquid viscosity for sand and for glass beads. The solid circulation rate increases with an increase in total velocity and auxiliary velocity, and also increases with increasing viscosity.

  7. Lateral Solids Mixing in the Dense Zone of a Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    YANGHairui; LUEJunfu; 等

    2002-01-01

    Lateral solid mixing was investigated experimentally in the dense zone of a 900mm×100mm×5.2m rectangular circulating fluidized bed riser.Using heated tracer injection,the lateral solid dispersion was determined by measuring the temperature response at different lateral positions. Furthermore, a one-dimensional dispersion model,which describes the solid mixing in the dense zone,is presented.The experimental results were used to determine the lateral particle dispersion coefficient under various operating conditions. A correlation of dispersion coefficient with bed height, gas velocity,and particle size is also proposed.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Orientation of cylindrical particles in gas-solid circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    Jie Cai; Qihe Li; Zhulin Yuan

    2012-01-01

    The orientation of cylindrical particles in a gas-solid circulating fluidized bed was investigated by establishing a three-dimensional Euler-Lagrange model on the basis of rigid kinetics,impact kinetics and gas-solid two-phase flow theory.The resulting simulation indicated that the model could well illustrate the orientation of cylindrical particles in a riser during fluidization,The influences of bed structure and operation parameters on orientation of cylindrical particles were then studied and compared with related experimental results.The simulation results showed that the majority of cylindrical particles move with small nutation angles in the riser,the orientation of cylindrical particles is affected more obviously by their positions than by their slenderness and local gas velocities.The simulation results well agree with experiments,thus validating the proposed model and computation.

  11. Carbon attrition during the circulating fluidized bed combustion of a waste-derived fuel

    Energy Technology Data Exchange (ETDEWEB)

    Arena, U. [Consiglio Nazionale delle Ricerche, Naples (Italy). Inst. for Combustion Research; Naples Univ. (Italy). Dept. of Environmental Sciences; Mastellone, M.L. [Naples Univ. Federico II (Italy). Dept. of Chemical Engineering

    1999-07-01

    A biomass obtained as residue from food manufacturing of pine nuts was batchwise fed in a laboratory scale circulating fluidized bed combustor. The apparatus was operated under both inert and oxidizing conditions in order to establish the relative importance of purely mechanical attrition and combustion-assisted attrition in generating carbon fines. For each run, carbon load and carbon particle size distribution in the riser and rates of attrited carbon fines escaping from the combustor were determined as a function of time. A parallel investigation was carried out with a bubbling fluidized bed combustor in order to point out peculiarities of attrition in the two apparatus. Results were compared with those obtained by burning in the same combustor a bituminous coal and a packaging-derived fuel, obtained from monomaterial collections of polyethylene terephtalate bottles. A different attrition phenomenology was found for each fuel and its peculiar features were taken into account. (orig.)

  12. Heat Transfer in a Liquid-Solid Circulating Fluidized Bed Reactor with Low Surface Tension Media

    Institute of Scientific and Technical Information of China (English)

    HR Jin; H Lim; DH Lim; Y Kang; Ki-Won Jun

    2013-01-01

    Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively. Effects of liquid velocity, particle size, surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid cir-culation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase, due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid veloc-ity even in the higher range, due to the solid circulation prevented the decrease in solid holdup, in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables.

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

    Science.gov (United States)

    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.

  14. Hydrodynamics of Biomass Gasification in a Dual Chamber Circulating Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Wahyu Haifa

    2016-01-01

    Full Text Available This paper presents work on hydrodynamics of several types of biomass mixture in a dual chamber circulating fluidized bed. In designing the CFBreactornecessary to know the distribution of solid particles radially and axially influenced by fluidizing gas velocity, particle size, solid circulation flux, reactor diameter and height of the reactor. These factors will affect pressure drop along the riser of the reaction chamber. Pressure drop is an important factor in the study of hydrodynamics of particle flow. The pressure drop was measured using mathematical model compared to experimental results done on a cold mode. Since it was found that both results were consistent which means that the model can be used to predict the operating parameters of CFB design.

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

    Science.gov (United States)

    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.

  16. Generation and reduction of nitrogen oxides in firing different kinds of fuel in a circulating fluidized bed

    Science.gov (United States)

    Munts, V. A.; Munts, Yu. G.; Baskakov, A. P.; Proshin, A. S.

    2013-11-01

    The processes through which nitrogen oxides are generated and reduced in the course of firing different kinds of fuel in a circulating fluidized bed are addressed. All experimental studies were carried by the authors on their own laboratory installations. To construct a model simulating the generation of nitrogen oxides, the fuel combustion process in a fluidized bed was subdivided into two stages: combustion of volatiles and combustion of coke residue. The processes through which nitrogen oxides are generated and reduced under the conditions of firing fuel with shortage of oxygen (which is one of efficient methods for reducing nitrogen oxide emissions in firing fuel in a fluidized bed) are considered.

  17. Study on biomass circulation and gasification performance in a clapboard-type internal circulating fluidized bed gasifier.

    Science.gov (United States)

    Zhou, Zhao-qiu; Ma, Long-long; Yin, Xiu-li; Wu, Chuang-zhi; Huang, Li-cheng; Wang, Chu

    2009-01-01

    We investigated the solid particle flow characteristics and biomass gasification in a clapboard-type internal circulating fluidized bed reactor. The effect of fluidization velocity on particle circulation rate and pressure distribution in the bed showed that fluidization velocities in the high and low velocity zones were the main operational parameters controlling particle circulation. The maximum internal circulation rates in the low velocity zone came almost within the range of velocities in the high velocity zone, when u(H)/u(mf)=2.2-2.4 for rice husk and u(H)/u(mf)=3.5-4.5 for quartz sand. In the gasification experiment, the air equivalence ratio (ER) was the main controlling parameter. Rice husk gasification gas had a maximum heating value of around 5000 kJ/m(3) when ER=0.22-0.26, and sawdust gasification gas reached around 6000-6500 kJ/m(3) when ER=0.175-0.24. The gasification efficiency of rice husk reached a maximum of 77% at ER=0.28, while the gasification efficiency of sawdust reached a maximum of 81% at ER=0.25.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. 生物质鼓泡流化床和循环流化床气化对比试验%Comparison of Bubbling Fluidized Bed and Circulating Fluidized Bed in Gasification of Biomass

    Institute of Scientific and Technical Information of China (English)

    范晓旭; 贤建伟; 初雷哲; 杨立国

    2011-01-01

    在内径为φ0.2 m、高6 m的流化床装置上,利用两种不同粒径的石英砂,分别进行了高速鼓泡流化床(BFB)和循环流化床(CFB)的冷态压力分布试验和热态气化试验.结果表明:冷态试验中,鼓泡流化床压力分布主要集中在底部的密相区,循环流化床压力分布更趋均匀.热态稳定气化阶段,循环流化床轴向温差只有40℃,气化的燃气热值、碳转化率和气化效率均高于鼓泡流化床.%The results from biomass gasification in a pilot-scale (6m tall × 0. 2 m internal diameter) air-blown circulating fluidized bed gasifier was tested and compared with bubbling fluidized bed gasifier. The results showed that the diameters of bed material in bubbling fluidized bed and circulating fluidized bed were different. The bubbling fluidized bed had a dense zone and bed material was homogeneous distribution in circulating fluidized bed. The temperature of the circulating fluidized bed was more uniform than bubbling fluidized bed. The carbon conversion rate, gasification efficiency and low gas heat value of circulating fluidized bed were larger than that of bubbling fluidized bed gasifier.

  1. Development of an Internally Circulating Fluidized Bed Membrane Reactor for Hydrogen Production from Natural Gas

    Institute of Scientific and Technical Information of China (English)

    XIE Dong-lai; GRACE John R; LIM C Jim

    2006-01-01

    An innovative Internally Circulating Fluidized Bed Membrane Reactor (ICFBMR) was designed and operated for ultra-pure hydrogen production from natural gas. The reactor includes internal catalyst solids circulation for conveying heat between a reforming zone and an oxidation zone. In the reforming zone, catalyst particles are transported upwards by reactant gas where steam reforming reactions are taking place and hydrogen is permeating through the membrane surfaces. Air is injected into the oxidation zone to generate heat which is carried by catalyst particles to the reforming zone supporting the endothermic steam reforming reaction. The technology development process is introduced: cold model test,pilot plant and industrial demonstration unit. The process flow diagram and key components of each unit are described.The ICFBMR process has the potential to provide improved performance relative to conventional SMR fixed-bed tubular reactors.

  2. THREE -PHASE CIRCULATING FLUIDIZED BED EVAPORATOR FOR WHEAT STRAW BLACK LIQUOR EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    Yuan-yuan Jia

    2004-01-01

    A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China′s papermaking industry. It is treated by alkali recovery,in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20% ~40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.

  3. THREE -PHASE CIRCULATING FLUIDIZED BED EVAPORATOR FOR WHEAT STRAW BLACK LIQUOR EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    Yuan-yuanJia

    2004-01-01

    A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China's papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20%-40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.

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

    Science.gov (United States)

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

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Model prediction of the operating behavior of a circulating fluidized bed boiler

    Institute of Scientific and Technical Information of China (English)

    王勤辉; 骆仲泱; 倪明江; 岑可法

    2002-01-01

    An improved mathematical model for a circulating fluidized bed (CFB) boiler based on the model developed earlier by the authors was applied to simulate the operation of a 12 MW CFB boiler. The influences of the excess air ratio, primary air ratio, coal particle size distribution, coal properties (ash content and volatile content) and Ca/S ratio on the boiler operation were analyzed. The results showed that the model simulation may be applied to the optimum design and economic operation of the CFB boiler.

  7. Feasibility of Combustion of Petroleum Coke in 230t/h Circulating Fluidized Bed Boiler

    Institute of Scientific and Technical Information of China (English)

    HAN Dong-tai; SONG Zheng-chang; XU Tao

    2003-01-01

    In order to reuse the high sulfur petroleum coke, the waste in chemical industry, as fuel of power plant for energy recovery, the combustion property of petroleum coke was researched experimentally in circulating fluidized bed (CFB) boiler. The performance of the boiler in burning mixed fuel with different ratios of coal to petroleum coke is obtained. Based on the experimental data, Factors influencing the stability of combustion,thermal efficiency of boiler, and emissions and desulphurisation are discussed. This study demonstrates that the combustion of petroleum coke in CFB boiler is applicable, and has great significance on the design and operation of CFB boiler to burn petroleum coke.

  8. Model prediction of the operating behavior of a circulating fluidized bed boiler

    Institute of Scientific and Technical Information of China (English)

    王勤辉; 骆仲泱; 倪明江; 岑可法

    2002-01-01

    An improved mathematical model for a circulating fluidized bed (CFB) boiler baaed on the model developed earlier by the authors was applied to simulate the operation of a 12 MW CFB boiler.The influences of the excess air ratio, primary air ratio, coal particle size distribution, coal properties (ash content and volatile content) and Ca/S ratio on the boiler operation were analyzed. The results showed that the model simulation may be applied to the optimum design and economic operation of the CFB boiler.

  9. Simulation of NOx emission in circulating fluidized beds burning low-grade fuels

    Energy Technology Data Exchange (ETDEWEB)

    Afsin Gungor [Nigde University, Nigde (Turkey). Faculty of Engineering and Architecture

    2009-05-15

    Nitrogen oxides are a major environmental pollutant resulting from combustion. This paper presents a modeling study of pollutant NOx emission resulting from low-grade fuel combustion in a circulating fluidized bed. The simulation model accounts for the axial and radial distribution of NOx emission in a circulating fluidized bed (CFB). The model results are compared with and validated against experimental data both for small-size and industrial-size CFBs that use different types of low-grade fuels given in the literature. The present study proves that CFB combustion demonstrated by both experimental data and model predictions produces low and acceptable levels of NOx emissions resulting from the combustion of low-grade fuels. Developed model can also investigate the effects of different operational parameters on overall NOx emission. As a result of this investigation, both experimental data and model predictions show that NOx emission increases with the bed temperature but decreases with excess air if other parameters are kept unchanged. 37 refs., 5 figs., 5 tabs.

  10. CFD modeling of stripper ash cooler of circulating fluidized bed boiler

    Directory of Open Access Journals (Sweden)

    Ravi Inder Singh

    2016-09-01

    Full Text Available The stable operation of a bottom ash cooler is vital for the operation of the circulating fluidized bed boiler. To assess, the stability of the ash cooler, it is important to have a thorough understanding of the flow behaviour. Although, many experimental results been reported in literature, CFD modelling of the ash cooler has not been carried out. In this paper, the transient computational analysis of a novel stripper ash cooler has been carried out using the Eulerian–Eulerian multiphase approach. The phase coupled SIMPLE algorithm has been used to solve the multiphase equations and the Gidaspow drag model has been employed to model the interaction between the fluidized air and ash. Two cases have been analysed in this paper. In the first case, the filling of the ash in the cooler has been analysed and in the second case, the phenomenon of fluidized bed bubbling in the ash cooler has been simulated. The study the of flow characteristics of hot ash has been studied. The contours of temperature, phase volume and bubbling have been analyzed in this paper.

  11. Flow Pattern Identification of Fluidized Beds Using ECT

    Institute of Scientific and Technical Information of China (English)

    S. Liu; W.Q. Yang; H. Wang; G. Yan; Z. Pan

    2001-01-01

    Electrical capacitance tomography (ECT) was applied in measuring solids distribution in square circulating fluidized beds. The fluidization conditions varied from bubbling fluidized bed to circulating fluidized bed. In the whole range of fluidization conditions, ECT was able to instantaneously provide the solids concentration and voids distributions in the fluidized beds. According to the acquired data from ECT and reconstructed image,different fluidization regimes can also be identified.

  12. Simulation of circulating fluidized bed gasification for characteristic study of pakistani coal

    Directory of Open Access Journals (Sweden)

    Ramzan Naveed

    2015-03-01

    Full Text Available A process model for turbulent pressurized circulating fluidized-bed coal gasifier is created using ASPEN PLUS software. Both hydrodynamic and reaction kinetics parameter are taken into account, whose expressions for fluidized bed are adopted from the literature. Various reactor models available in ASPEN PLUS with calculator as External Block are nested to solve hydrodynamics and kinetics. Multiple operational parameters for a pilot-plant circulating fluidized-bed coal gasifier are used to demonstrate the effects on coal gasification characteristics. This paper presents detailed information regarding the simulation model, including robust analysis of the effect of stoichiometric ratio, steam to coal ratio, gasification temperature and gasification agent temperature. It is observed that, with the increase in the flow rate of air, the components hydrogen, carbon monoxide, carbon dioxide and methane reduce, which causes the Lower Heating Value (LHV of synthesis gas (Syn. Gas to decrease by about 29.3%, while increment in the steam flow rate shows a minute increase in heating value of only 0.8%. Stoichiometric ratio has a direct relationship to carbon conversion efficiency and carbon dioxide production. Increasing the steam to coal ratio boosts the production of hydrogen and carbon monoxide, and causes a drop in both carbon dioxide concentration and the conversion efficiency of carbon. High gasifying agent temperature is desired because of high concentration of CO and H2, increasing carbon conversion and LHV. A high gasifying agent temperature is the major factor that affects the coal gasification to enhance H2 and CO production rapidly along with other gasification characteristics.

  13. Thermodynamic analysis of the gasification of coal water slurry fuels for a circulating fluidized bed gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, H.; Yavuzkurt, S.; Scaroni, A. [National Taiwan University, Taipei (Taiwan)

    2002-07-01

    To validate the concept of coal gasification in the integrated coal gasification combined cycle (IGCC), a novel laboratory gasifier consisting of a circulating fluidized bed and a cyclone combustor has been constructed. This paper reports a thermodynamic analysis conducted to predict the maximum capacity and the condition for best operation of this circulating fluidized bed gasifier, which has an inside diameter of 0.3048 m and a height of 2.5 m. The equilibrium feed rates of materials and the quality of the product gas are described as a function of the reactor temperature, the thermal capacity of the gasifier, and the water concentration in coal water slurry fuel. The results of parametric analysis show that the thermal efficiency decreases, but the efficiency of desulfurization increases as the reactor temperature increases. The thermal capacity of the gasifier has no influence on the quality of the product gas. The thermal efficiency and the efficiency of desulfurization decrease as the water concentration in the coal water slurry increases. The desulfurization in the gasifier at equilibrium conditions is very efficient and meets the EPA regulations of the USA.

  14. Surface Modification of Fine Particle by Plasma Grafting in a Circulating Fluidized Bed Reactor under Reduced Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sounghee [Woosuk University, Jinchon (Korea, Republic of)

    2015-10-15

    A plasma surface modification of powders has been carried out in a circulating fluidized bed reactor under reduced pressure. Polystyrene (PS) particles treated by plasma are grafted with polyethylene glycol (PEG) on the surface. The virgin, plasma-treated and grafted powders were characterized by DPPH method, FTIR, SEM and contact angle meter. The plasma-treated PS powders have well formed peroxide on the surface, By PEG grafting polymerization, PEG is well grafted and dispersed on the surface of the plasma-treated PS powders. The PEG-g-PS particle was successfully synthesized using the plasma circulating fluidized bed reactor under reduced pressure.

  15. [Intermediate experiment and mechanism analysis of flue gas desulfurization technology by circulating fluidized bed].

    Science.gov (United States)

    Zhao, Xudong; Wu, Shaohua; Ma, Chunyuan; Qin, Yukun

    2002-03-01

    A new Circulating Fluidized Bed was designed for intermediate experiment of flue gas desulphurization, in which the flue gas flow rate was 3500 m3/h. By using it, the basic experiments were carried out to study the influence of Ca/S and supersaturated temperature on desulphurization efficiency and the effect of the recycling solid particle in the sulfur removal column on desulphurization performance. The results showed when Ca/S = 1.2, the desulphurization efficiency was increased by 15% through the recycle of solid particle; the gas velocity inside the bed could be designed higher. The mechanism analysis were also studied and the method to increase effective resident time was introduced.

  16. Synthesis gas production using oxygen storage materials as oxygen carrier over circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    DAI Xiaoping; YU Changchun; LI Ranjia; WU Qiong; HAO Zhengping

    2008-01-01

    A novel process for synthesis gas production over Circulating Fluidized Bed (CFB) using oxygen storage materials as oxygen carrier was reported. First, oxygen in the air was chemically fixed and converted to lattice oxygen of oxygen storage materials over regenerator, and then methane was selectively oxidized to synthesis gas with lattice oxygen of oxygen storage materials over riser reactor. The results from simulation reaction of CFB by sequential redox reaction on a fixed bed reactor using lanthanum-based perovskite LaFeO3 and La0.8Sr0.2Fe0.9Co0.1O3 oxides prepared by sol-gel, suggested that the depleted oxygen species could be regenerated, and methane could be oxidized to synthesis gas by lattice oxygen with high selectivity. The partial oxidation of methane to synthesis gas over CFB using lattice oxygen of the oxygen storage materials instead of gaseous oxygen should be possibly applicable.

  17. An Experimental Investigation on Solid Acceleration Length in the Riser of a Long Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Systematic experimental work was conducted to investigate the solid acceleration length in a 16m long circulating fluidized bed riser with fluid cracking catalyst particles over a wide range of operating conditions. A more feasible method is proposed to determine the acceleration length from the measured axial profiles of pressure gradient (or apparent solid holdup). With this new method and large amount of experimental data, a clear picture on the variation of the acceleration length with both solid circulating rate and superficial gas velocity is obtained.It is found that the acceleration length increases generally with increasing solid flow rate and/or decreasing gas velocity. However, the trend in variation of the acceleration length with operating conditions are quite different in different operation ranges. Reasonable explanations are suggested for the observed variation patterns of acceleration length.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Rotational asymmetry of reactant concentration and its evolution in a circulating fluidized bed riser

    Institute of Scientific and Technical Information of China (English)

    Dongbing Li; Ajay K. Ray; Madhumita B. Ray; Jesse Zhu

    2012-01-01

    Rotational asymmetric distribution of reactant (ozone) concentration and its evolution along with the gas-solid reactive flow were studied in a 76 mm i.d.,10.2 m high circulating fluidized bed (CFB) riser reactor.The superficial gas velocity ranged from 3 to 5 m/s and the solids circulation rates were 50 and 100kg/(m2 s).Experimental results show that the asymmetry of reactant distribution can extend to a height close to the length of flow developing zone of the CFB riser reactor and then disappears.Based on the hydrodynamics of the gas and solid phases in the solids entrance region,this asymmetry can be attributed to the effect of the solids entrance structure.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Properties of Concrete Incorporating Bed Ash from Circulating Fluidized Bed Combustion and Ground Granulates Blast-furnace Slag

    Institute of Scientific and Technical Information of China (English)

    CHENG An; HSU Hui-Mi; CHAO Sao-Jeng

    2011-01-01

    The properties of concrete incorporating circulating fluidized bed combustion (CFBC) bed ash and ground granulates blast-furnace slag (GGBS) were studied. Compressive strength,drying shrinkage, mercury intrusion porosimetry (MIP), scanning electronic microscopy (SEM), and X-ray diffraction (XRD) of concrete samples containing CFBC bed ash and GGBS were used. This work used initial surface absorption test (ISAT) and rapid chloride penetration test (RCPT) on concrete to measure the absorption and the ability of concrete to resist chloride ion characteristics for different concrete samples containing CFBC bed ash and GGBS. Open circuit potential (OCP), direct current polarization resistance were obtained to evaluate rebar corrosion. The CFBC bed ash was X-ray amorphous and consist of SiO2, A12O3 and CaO compounds. As the replacement of CFBC for sand increases, the rate of initial surface absorption (ISA) increases but compressive strength decreases.When the content of CFBC bed ash replacement for sand maintains constant, the replacement of GGBS for cement increases, compressive strength increases but the rate of ISA decreases. Chloride and corrosion resistance of rebar significantly improve by utilizing a proper amount of CFBC bed ash and GGBS in concrete.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Błaszczuk Artur

    2015-09-01

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

    Science.gov (United States)

    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.

  6. Effect of Liquid Viscosity and Solid Inventory on Hydrodynamics in a Liquid - solid Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Nirmala sundaram

    2017-01-01

    Full Text Available A comprehensive hydrodynamic study of a Liquid - Solid Circulating Fluidized Bed (LSCFB is conducted with changes in viscosity of the fluidizing medium and the inventory height of solids initially fed into the system. An LSCFB of height 2.95m and riser outer diameter 0.1m was chosen for experimentation. The three liquid media systems with varying viscosities that were chosen were water, glycerol 10% (v/v and glycerol 20% (v/v. Effect of inventory on the hydrodynamics was also studied, by taking initial heights of inventory to be 15cm, 25cm and 35cm. The hydrodynamic studies concentrated on pressure gradients along the axial pressure tapings, axial solid holdup, average solid holdup, solid circulation rate and slip velocity. Uniformity in axial solid holdup and average solid holdup was validated for changes in viscosity and inventory. Solid flux was seen to follow an inverse relationship to holdup. The changes in slip velocity with varying viscosity and inventory were studied, and found to decrease with both variables. The distribution parameter, Co of the drift flux model was found to be in the range of 0.983-0.994, suggesting non-uniformity in radial solid distribution, with higher solid concentration by the walls compared to the core of the column.

  7. Gas-solid two-phase turbulent flow in a circulating fluidized bed riser: an experimental and numerical study

    NARCIS (Netherlands)

    He, Y.; Sint Annaland, van M.; Deen, N.G.; Kuipers, J.A.M.

    2006-01-01

    Hydrodynamics of gas-particle two-phase turbulent flow in a circulating fluidized bed riser is studied experimentally by Particle Image Velocimetry (PIV) and numerically with the use of a 3D discrete hard sphere particle model (DPM). Mean particle velocities and RMS velocities are obtained and the i

  8. Gas-Solid Turbulent Flow in a Circulating Fluidized Bed Riser; Numerical Study of Binary Particle Mixtures

    NARCIS (Netherlands)

    He, Y.; Deen, N.G.; Sint Annaland, van M.; Kuipers, J.A.M.

    2008-01-01

    A numerical simulation was performed on a turbulent gas-particle multi-phase flow in a circulating fluidized bed riser based on a hard-sphere discrete particle model (DPM) for the particle phase and the Navier-Stokes equations for the gas phase. The sub-grid scale stresses (SGS) were modeled with th

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

    Science.gov (United States)

    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.

  10. The Simulation of Influence of Different Coals on the Circulating Fluidized Bed Boiler's Combustion Performance

    Institute of Scientific and Technical Information of China (English)

    Yumei Yong; Qinggang Lu

    2003-01-01

    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.

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

    Science.gov (United States)

    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.

  12. Solid holdup in liquid solid circulating fluidized bed with viscous liquid medium

    Directory of Open Access Journals (Sweden)

    Nirmala Gnanasundaram

    2014-12-01

    Full Text Available Average solid holdup in the axial direction was investigated in a liquid solid circulating fluidized bed riser (LSCFB, with liquids of different viscosities. The effect of operating parameters including; primary, secondary and total velocity, particle diameter and density was studied. Experiments were conducted using water and glycerol at different concentration having viscosities in the range 1–1.36 cp. The results indicated that the solid holdup in the riser was axially uniform for viscous liquids and increases with increase in auxiliary velocity. The average solid holdup decreases with increase in total velocity and increases with increase in viscosity for sand–glycerol, glass bead–glycerol system. The experimental measurements were compared with the existing holdup model prediction that varied linearly with viscosity. Further, a correlation was developed to estimate average solid holdup in the riser, and the performance of the expression was compared with the present experimental data.

  13. Continuous protein recovery from whey using liquid-solid circulating fluidized bed ion-exchange extraction.

    Science.gov (United States)

    Lan, Qingdao; Bassi, Amarjeet; Zhu, Jing-Xu Jesse; Margaritis, Argyrios

    2002-04-20

    A liquid-solid circulating fluidized bed (LSCFB) continuous ion-exchange extraction system has been investigated for total protein recovery from whey solutions under various operating conditions. The effectiveness of a dynamic seal was evaluated between the riser and the downcomer, and the best conditions for the establishment of this seal were established. Start-up studies indicated that the system is robust and stable. Under optimal conditions, a productivity of 8.2 g of total protein removed per hour per kilogram of resin was achieved with a protein removal efficiency of 78.4%. However, higher overall protein recovery of up to 90% was also achieved under other conditions, with lower protein concentration in the effluent and a lower overall productivity.

  14. Strength and thermal behavior of low weight foam geopolymer using circulating fluidized bed combustion fly ash

    Institute of Scientific and Technical Information of China (English)

    刘泽; 邵宁宁; 秦俊峰; 孔凡龙; 王春雪; 王栋民

    2015-01-01

    A comparative study of the influence of elevated temperature on foam geopolymer using circulating fluidized bed combustion fly ash (CFA) was reported. Foam geopoymers were prepared with different amounts of foam agent and different SiO2/Al2O3 molar ratios of 3.1, 3.4, and 3.8. The mechanical, thermo-physical properties and microstructure of the foam geopolymers before and after exposure to elevated temperature of 800, 1000, and 1200 °C were investigated. The specimen with SiO2/Al2O3 molar ratio of 3.8 exhibits the highest compressive strength, better microstructure and dimension stability before and after firing. Carnegeite, nepheline, and zeolite crystalline phases appearing after exposure may contribute to the good post-exposure strength. Low weight foam geopolymer using CFA can increase strength and maintain higher stability as high as 1000 °C.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  17. Study on Reactivity of Circulating Fluidized Bed Combustion Fly Ashes in the Presence of Water

    Directory of Open Access Journals (Sweden)

    Salain I.M.A.K.

    2010-01-01

    Full Text Available A study on reactivity of four different Circulating Fluidized Bed Combustion (CFBC fly ashes has been realized in the presence of water. Paste of each ash was prepared and analyzed for its setting time, expansion and strength. The products of hydration, and their evolutions over a period of time were identified by X-ray diffraction and differential thermal analysis. The results of this study show that the reactivity of the CFBC fly ashes is strongly related to their chemical composition, essentially to their quantity of silica, alumina, lime and sulfate, which promote principally the formation of ettringite, gypsum and C-S-H. It is further noted that the intensity and the proportion of these phases determine the hydration behavior of the CFBC fly ashes.

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

    Science.gov (United States)

    Patil, M P; Sonolikar, R L

    2008-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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}.

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

    Science.gov (United States)

    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.

  1. Analysis of microalgae pellets combustion in a circulating fluidized-bed

    Directory of Open Access Journals (Sweden)

    Kosowska-Golachowska Monika

    2017-01-01

    Full Text Available Microalgae are expected to become an important source of highvalue products with several applications in a large number of areas of biotechnology and, especially, in biofuels production. The increasing interest in microalgae as a source of biofuel (so-called third generation biofuel is due to the several advantages. The objective of this study was to investigate combustion characteristics of microalgae (Oscillatoria sp. pellets burnt in a circulating fluidized-bed (CFB in terms of sample temperature profiles, ignition time, ignition temperature, devolatilization time and the burnout time. Spherical 10-mm microalgae pellets were tested at temperature of 850°C in a 12-kW bench-scale CFB combustor.

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

    Institute of Scientific and Technical Information of China (English)

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

    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 elec-tron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF). The CFA-based foam geopolymer was successfully fabri-cated 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.

  3. NO{sub x} formation and destruction in circulating fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Munts, V.A.; Lecomtseva, U.G.; Baskakov, A.P.; Putrick, S.B. [Ural State Technical Univ., Ekaterinburg (Russian Federation)

    2002-07-01

    In general, nitrogen oxides are formed in circulating fluidized bed combustors (CFBC) because of fuels that contain nitrogen. This paper describes how nitrogen oxide (NO{sub x}) is formed during the coal burning process. Two consecutive reactions occur. The first is the homogeneous oxidation of nitrogen-containing volatiles followed by the heterogeneous oxidation of char-bound nitrogen on the char surface. Kinetic constants of the oxidation reaction for nitrogen-containing volatile species were also determined for nitrogen contained in a coke residue. The rate of NO{sub x} reduction on the surface of char particles was also measured to calculate NO{sub x} concentrations in CFBC. It was determined that the estimated fraction of char-bound nitrogen converted into NO{sub x}, depends on the nitrogen content of the fuel and on the ratio of rate constants of nitrogen and carbon oxidation. 10 refs., 1 tab., 4 figs.

  4. Heat transfer in a large-scale circulating fluidized bed boiler

    Institute of Scientific and Technical Information of China (English)

    CHENG Leming; WANG Qinhui; SHI Zhenglun; LUO Zhongyang; NI Mingjiang; CEN Kefa

    2007-01-01

    Heat transfer of a furnace in a large-scale circulating fluidized bed (CFB) boiler was studied based on the analysis of available heat transfer coefficient data from typical industrial CFB boilers and measured data from a 12 MWe,a 50 MWe and a 135 MWe CFB boiler.The heat transfer of heat exchanger surfaces in a furnace,in a steam/water cooled cyclone,in an external heat exchanger and in the backpass was also reviewed.Empirical correlation of heat transfer coefficient was suggested after calculating the two key parameters,solids suspension density and furnace temperature.The correlation approach agrees well with the data from the large-scale CFB boilers.

  5. Second law analysis of heat transfer surfaces in circulating fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Gungor, Afsin [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Nigde University, 51100 Nigde (Turkey)

    2009-07-15

    The correct sizing of the heat transfer surfaces is important to ensure proper operation, load turndown, and optimization of circulating fluidized beds (CFBs). From this point of view, in this study, the thermodynamic second law analysis of heat transfer surfaces in CFBs is investigated theoretically in order to define the parameters that affect the system efficiency. Using a previously developed 2D CFB model which uses the particle-based approach and integrates and simultaneously predicts the hydrodynamics and combustion aspects, second law efficiency and entropy generation values are obtained at different height and volume ratios of the heat transfer surfaces for CFBs. Besides that, the influences of the water flow rates and heat exchanger tube diameters on the second law efficiency are investigated. Through this analysis, the dimensions, arrangement and type of the heat transfer surfaces which achieve maximum efficiency are obtained. (author)

  6. Biomass gasification in a circulating fluidized bed; Vergasung von Biomasse in der zirkulierenden Wirbelschicht

    Energy Technology Data Exchange (ETDEWEB)

    Ising, M.; Hoelder, D.; Backhaus, C.; Althaus, W. [Fraunhofer Inst. fuer Umwelt-, Sicherheits- und Energietechnik UMSICHT, Oberhausen (Germany)

    1998-09-01

    Biomass gasification in a circulating fluidized bed, in combination with a gas engine or gas burner, is a promising option for energetic use of biomass. Economic efficiency analyses on the basis of the UMSICHT plant show that this technology for combined heat and power generation from biomass is promising also for the range below 10 MW. The economic situation of any plant must be considered for the specific boundary conditions imposed by the power supply industry. The feasibility of the process was tested in a demonstration plant at Oberhausen. The plant was optimized further in extensive test series, and a number of tar reduction processes were investigated and improved on. The authors now intend to prove that gasification in a circulating fluidized bed combined with a gas engine cogeneration plant is feasible in continuous operation. (orig./SR) [Deutsch] Die Vergasung von Biomasse in der zirkulierenden Wirbelschicht ist in Kombination mit einem Gasmotor oder einem Gasbrenner eine vielversprechende Option fuer die energetische Biomassenutzung. Wirtschaftlichkeitsbetrachtungen auf Basis der UMSICHT-Anlage zeigen, dass diese Technologie fuer die gekoppelte Strom- und Waermeerzeugung aus Biomasse auch im Leistungsbereich unter 10 MW grosse Chancen verspricht. Dabei ist die oekonomische Situation einer Anlage im Einzelfall unter Beachtung der energiewirtschaftlichen Randbedingungen zu beurteilen. Durch den Betrieb einer Demonstrationsanlage in Oberhausen konnte die Funktion des Verfahrens nachgewiesen werden. In weiteren umfangreichen Versuchsreihen werden die Anlage weiter optimiert und verschiedene Konzepte zur Teerminderung untersucht und weiterentwickelt. Angestrebt ist der Nachweis des Dauerbetriebs von ZWS-Vergasung zusammen mit dem Gasmotoren-BHKW. (orig./SR)

  7. Circulating pressurized fluidized bed. Trial operation, phase 1c. Final report; Zirkulierende Druckwirbelschicht. Versuchsbetrieb, Phase 1c. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Krein, J.; Schmitt, J.; Wedel, G. von; Winkler, K.

    1993-09-01

    Since March `89, the Deutsche Babcock Energie und Umwelttechnik AG have been operating a 15 MW{sub th} experimental pressurized fluidized bed facility. The plant was first designed as a stationary pressurized fluidized bed and was optimized and tested in a 2000-h period of trial operation. In view of the good results of the plant and the technical superiority of the circulating fluidized bed technology, the experimental facility was converted into a circulating pressurized fluidized bed system. The reconstruction work was started in February `91, and from October `91 onwards the circulating pressurized fluidized bed system was optimized and tested in a 900-h trial operation period. This report explains the concept of circulating pressurized fluidized bed technology as applied by the Deutsche Babcock Energie und Umwelttechnik AG and presents the results of circulating trial operation. The results of circulating and stationary fluidized bed trial operation are compared. This comparison is particularly significant as all marginal systems of the plant, i.e. for combustion air supply, flue gas discharge, coal supply and ash removal, have remained unmodified during the reconstruction phase. (orig.) [Deutsch] Seit Maerz `89 betreibt die Deutsche Babcock Energie und Umwelttechnik AG eine 15 MW{sub th} Druckwirbelschicht Versuchsanlage. In einer ersten Versuchsphase wurde die Anlage als stationaere Druckwirbelschicht konzipiert und in einem 2000-stuendigen Versuchsbetrieb optimiert und getestet. Ausgehend von den guten Ergebnissen aus dem stationaeren, druckaufgeladenen Versuchsbetrieb und in Anbetracht der aus dem atmosphaerischen Bereich bekannten Vorteile der zirkulierenden gegenueber der stationaeren Wirbelschicht wurde die Versuchsanlage ab Februar `91 in eine zirkulierende Druckwirbelschicht umgebaut. Ab Oktober `91 wurde die zirkulierende Druckwirbelschicht in einem 900-stuendigen Versuchsbetrieb optimiert und getestet. In diesem Bericht wird das von der Deutsche

  8. MULTISTAGE FLUIDIZED BED REACTOR

    Science.gov (United States)

    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.

  9. Spectral analysis of CFB data: Predictive models of Circulating Fluidized Bed combustors. 11th technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Gamwo, I.K.; Miller, A.; Gidaspow, D.

    1992-04-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Spectral analysis of CFB data obtained at Illinois Institute of Technology shows that the frequencies of pressure oscillations are less than 0.1 Hertz and that they increase with solids volume fraction to the usual value of one Hertz obtained in bubbling beds. These data are consistent with the kinetic theory interpretation of density wave propagation.

  10. Chemical looping reactor system design double loop circulating fluidized bed (DLCFB)

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    Chemical looping combustion (CLC) is continuously gaining more importance among the carbon capture and storage (CCS) technologies. It is an unmixed combustion process which takes place in two steps. An effective way to realize CLC is to use two interconnected fluidized beds and a metallic powder circulating among them, acting as oxygen carrier. The metallic powder oxidizes at high temperature in one of the two reactors, the air reactor (AR). It reacts in a highly exothermic reaction with the oxygen of the injected fluidising air. Afterwards the particles are sent to the other reactor where the fuel is injected, the fuel reactor (FR). There, they transport heat and oxygen necessary for the reaction with the injected fuel to take place. At high temperatures, the particle's oxygen reacts with the fuel producing Co2 and steam, and the particles are ready to start the loop again. The overall reaction, the sum of the enthalpy changes of the oxygen carrier oxidation and reduction reactions, is the same as for the conventional combustion. Two are the key features, which make CLC promising both for costs and capture efficiency. First, the high inherent irreversibility of the conventional combustion is avoided because the energy is utilized stepwise. Second, the Co2 is intrinsically separated within the process; so there is in principle no need either of extra carbon capture devices or of expensive air separation units to produce oxygen for oxy-combustion. A lot of effort is taking place worldwide on the development of new chemical looping oxygen carrier particles, reactor systems and processes. The current work is focused on the reactor system: a new design is presented, for the construction of an atmospheric 150kWth prototype working with gaseous fuel and possibly with inexpensive oxygen carriers derived from industrial by-products or natural minerals. It consists of two circulating fluidized beds capable to operate in fast fluidization regime; this will increase the

  11. Proceedings of the 7. international conference on circulating fluidized bed technology. 7. vol. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Grace, J.R. (ed.) [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Zhu, J.; De Lasa, H. [Western Ontario University, London, ON (Canada). Dept. of Biochemical and Chemical Engineering

    2002-07-01

    This conference brought together all of the major circulating fluidized bed (CFB) research groups from around the world and provided a major source of information on CFB and related topics. These proceedings focus on applications and fundamentals of CFB technology, including fluid catalytic cracking of hydrocarbons, CFB combustion of coal, calcination, gasification, pyrolysis, roasting of ores, and desulphurization. Several papers discussed the application of computational fluid dynamics to CFB, hydrodynamics, heat transfer and combustion. Discussions also focused on the importance of maintaining safety, providing sufficient heat transfer, and minimizing emissions of particulates and gaseous pollutants. The 9 sessions of the conference were entitled as follows: (1) invited overview papers, (2) downers, (3) heat and mass transfer, (4) hydrodynamics and mixing, (5) computational fluid dynamics and other models, (6) liquid fluidization and three-phase systems, (7) solids separation and return systems, (8) combustion and other gas-solid reactions, and (9) fluid catalytic cracking and other reactions. More than 100 papers were presented at the conference, of which 25 have been indexed separately for inclusion in this database. refs., tabs., figs.

  12. Influence of Chemical and Thermodynamic Parameters on the Flue Gas Desulphurization Efficiency in a Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    Baoguo FAN; Changfu YOU; Haiying QI; Guangming XIANG; Xuchang XU

    2001-01-01

    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.

  13. Modelling of N2O Reduction in a Circulating Fluidized Bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars Erik; Dam-Johansen, Kim;

    1996-01-01

    The addition of limestone for sulphur retention in Fluidized Bed Combustion (FBC) has been observed to influence the emission of N2O, and in many cases a lower emission was observed. The catalytic activity of a Danish limestone (Stevns Chalk) for decomposition of N2O in a laboratory fixed bed...

  14. Fluidized bed calciner apparatus

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  17. Investigation of the baffle effects on reactor of fluidized beds with circulating flow along with ozone decomposition

    Directory of Open Access Journals (Sweden)

    E. Zohrabi

    2016-09-01

    Full Text Available Fluidized beds with circulating flow, as the gas-solid contactors, are widely used in physical and chemical processes such as drying of solids, pharmaceutical industries, coating solids, granulation, and water and wastewater treatment industry. In this study, numerical simulation using FLUENT software was conducted to investigate the distribution of solid particles of fluidized beds with circulating flow. To conduct simulation, Eulerian-Eulerian with the help of kinetic theory of granular flow was used. Various values of particle-wall elastic modulus were studied. After selecting the appropriate model to predict the particles flow behavior, ozone decomposition reaction was carried out in fluidized beds with circulating flow and they were solved by FLUENT software. The results showed that the location of ring baffles has the greatest impact on fluctuation of system pressure drop, and adverse mix of gas and increase of solid materials are tangible by baffles, resulting from regulation of bed and accumulation of circulating particles beside the wall.

  18. Impact of worm predation on pseudo-steady-state of the circulating fluidized bed biofilm reactor.

    Science.gov (United States)

    Li, Ming; Nakhla, George; Zhu, Jesse

    2013-01-01

    This paper studies integrated simultaneous carbon and nitrogen removal as well as worm predation, in a circulating fluidized bed biofilm reactor (CFBBR) operated with an anoxic-aerobic bioparticle recirculation. A lab-scale CFBBR with a 8.5-liter reaction zone comprising 2L anoxic and 6.5L aerobic compartments was designed to evaluate the aquatic Oligochaete worm effect. Long-term (200 days) performance showed that stable and high-rate chemical oxygen demand (COD) with sodium acetate as the carbon source and total nitrogen (NH(4)Cl as nitrogen source) conversions were achieved simultaneously, with low sludge production of 0.082 g VSS (volatile suspended solids) g COD(-1) at pseudo-steady-state. Worm predation, which causes considerable sludge reduction of the bioparticle process, was studied. The results proved that the worm predation has a significant impact on the pseudo-steady-state performance of the CFBBR, decreasing biomass yield, decreasing oxygen concentration and increasing expanded bed height.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Modeling of NO and N{sub 2}O emissions from biomass circulating fluidized bed combustors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H.; Gibbs, B.M. [Leeds Univ., Leeds (United Kingdom). Dept. of Fuel and Energy

    2002-07-01

    In order to correctly model biomass combustion in a circulating fluidized bed (CFB) combustor, it is necessary to examine the four main stages in the combustion of biomass particles. These include drying, devolatilization, volatile combustion and char combustion in a CFB combustor. This paper presents a newly developed model for nitric oxide (NO) and nitrous oxide (N{sub 2}O) emissions from biomass-fired CFB combustors. A typical woody biomass of pinewood chips was selected for the model parameters. The drying and devolatilization of biomass particles was modeled with limited rates according to woody biomass fuels. The partition of fuel nitrogen between volatiles and char was chosen for pinewood based on available data from literature. It was assumed that the volatile nitrogen was composed of ammonia (NH{sub 3}), hydrogen cyanide (HCN) and nitrogen (N{sub 2}). The model included 25 chemical reactions, of which 20 belonged to global fuel-nitrogen reaction kinetics. A 12 MW CFB boiler was used to apply the model. Results were compared with experimental values as well as data from literature. The reaction between NO and char was found to be the key reaction that determines NO emissions. The catalytic effect of bed materials on the oxidation of NH{sub 3} and the the homogeneous reaction of NH{sub 3} with nitric oxide was also significant. 25 refs., 2 tabs., 5 figs.

  2. Modelling and simulation of a circulating fluidized-bed steam generator as an aid for process analysis and automation. Modellierung und Simulation eines ZWS-Dampferzeugers als Hilfsmittel zur Prozessanalyse und -automatisierung

    Energy Technology Data Exchange (ETDEWEB)

    Karbach, A.; Peters, R.; Schaub, G. (Lurgi GmbH, Frankfurt am Main (Germany, F.R.))

    1990-04-01

    This book deals with the development and application of mathematical model for the simulation of a steam generator with fluidized-bed combustion (coal combustion in the circulating fluidized-bed combustion). (orig./EF).

  3. Experimental Study on Gas—Solid Mass Transfer in Circulating Fluidized Beds.

    Institute of Scientific and Technical Information of China (English)

    WANGLinna; ZHANGLing; 等

    2002-01-01

    This study is devoted to gas-solid mass transfer behavior in heterogeneous two-phase flow. Experiments were carried out in a cold circulating fluidized bed of 3.0m in height and 72mm in diameter with naphthalene particles. Axial and radial distributions of sublimated naphthalene concentration in air were measured with an online concentration monitoring system HP GC-MS. Mass transfer coefficients were obtained under various operating condition, showing that heterogeneous flow structure strongly influences the axial and radial profiles of mass transfer coefficients. In the bottom dense region, mass transfer rate is high due to intensive dynamic behavior and higher relative slip velocity between gas and clusters. In the middle transition region and the upper diluter region, as a result of low mass transfer driving force and the influence of flow structure, mass transfer rate distribution becomes non-uniform. In conclusion, among the operating parameters influencing mass transfer coefficients, the superficial gas velocity is the most important factor and the solid circulation rate should be also taken into account.

  4. Fluidization quality analyzer for fluidized beds

    Science.gov (United States)

    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.

  5. Cocurrent downflow circulating fluidized bed (downer) reactors - a state of the art review

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.-X.; Yu, Z.-Q.; Jin, Y.; Grace, J.R.; Issangya, A. [University of Western Ontario, London, ON (Canada). Department of Chemical and Biochemical Engineering

    1995-10-01

    A new type of chemical reactor known as the cocurrent downflow fluidized bed reactor (or reversed riser reactor or downer reactor), that overcomes some of the disadvantages of the riser reactor, is described. Since both the gas and solids flow directions are downwards in the cocurrent downflow fluidized bed reactor, particle residence times are uniform, and there is no backmixing. The literature on downer studies is reviewed. Laboratory results on axial voidage profiles, pressure profiles, radial flow, mixing and residence time distribution, heat transfer, and particle velocities are summarized. Suggestions are made both for possible industrial applications of downer reactors and for suitable research directions. 56 refs., 18 figs., 1 tab.

  6. 循环流化床提升管反应器的放大问题%Scaling-up Problems of Circulating Fluidized Bed Riser Reactor

    Institute of Scientific and Technical Information of China (English)

    张坤

    2015-01-01

    简要介绍了循环流化床提升管反应器流体动力学的复杂性,详细总结了循环流化床提升管反应器的放大效应,并讨论了循环流化床的放大方法和循环流化床的放大准则.最后,对循环流化床放大问题进行了展望.%The complexity of fluid dynamics in circulating fluidized bed riser reactor was briefly introduced in this paper. Furthermore, the scaling-up effects of circulating fluidized bed riser reactor were summarized in detail. Then, the scaling-up methods and criterions of circulating fluidized bed riser reactor were discussed. At last, the future development of scaling-up problems of circulating fluidized bed was prospected.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Chemical looping reactor system design double loop circulating fluidized bed (DLCFB)

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    Chemical looping combustion (CLC) is continuously gaining more importance among the carbon capture and storage (CCS) technologies. It is an unmixed combustion process which takes place in two steps. An effective way to realize CLC is to use two interconnected fluidized beds and a metallic powder circulating among them, acting as oxygen carrier. The metallic powder oxidizes at high temperature in one of the two reactors, the air reactor (AR). It reacts in a highly exothermic reaction with the oxygen of the injected fluidising air. Afterwards the particles are sent to the other reactor where the fuel is injected, the fuel reactor (FR). There, they transport heat and oxygen necessary for the reaction with the injected fuel to take place. At high temperatures, the particle's oxygen reacts with the fuel producing Co2 and steam, and the particles are ready to start the loop again. The overall reaction, the sum of the enthalpy changes of the oxygen carrier oxidation and reduction reactions, is the same as for the conventional combustion. Two are the key features, which make CLC promising both for costs and capture efficiency. First, the high inherent irreversibility of the conventional combustion is avoided because the energy is utilized stepwise. Second, the Co2 is intrinsically separated within the process; so there is in principle no need either of extra carbon capture devices or of expensive air separation units to produce oxygen for oxy-combustion. A lot of effort is taking place worldwide on the development of new chemical looping oxygen carrier particles, reactor systems and processes. The current work is focused on the reactor system: a new design is presented, for the construction of an atmospheric 150kWth prototype working with gaseous fuel and possibly with inexpensive oxygen carriers derived from industrial by-products or natural minerals. It consists of two circulating fluidized beds capable to operate in fast fluidization regime; this will increase the

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

    Energy Technology Data Exchange (ETDEWEB)

    Dubose, R.E.; Ray, D.M. [Univ. of North Carolina, Chapel Hill, NC (United States); 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.

  12. An Experimental and Computational Study of Multiphase Flow Behaviour in Circulating Fluidized Beds

    Energy Technology Data Exchange (ETDEWEB)

    Mathiesen, Vidar

    1997-12-31

    Gas/solid flows have been studied extensively, mainly because they are important in nuclear, chemical and petroleum industries. This thesis describes an experiment done at two different circulating fluidized bed systems. Laser Doppler anemometry (LDA) and phase Doppler anemometry (PDA) were used to measure mean and fluctuating velocity, diameter and solids concentration. A typical core-annulus flow was obtained in both cases. The measurements show a relative mean velocity as well as a relative fluctuating velocity between different particle sizes. An axial segregation by size and its variation with the superficial gas velocity are demonstrated. Significant radial segregation is found in both risers. A three-dimensional Computational Fluid Dynamics model was developed based on Eulerian description of the phases where the kinetic theory of granular flow is the basis of the turbulence modelling in the solid phases. There are one gas phase and any number of solid phases. Simulations of flow behaviour in two- and three-dimensions agree well with experiments and the model is able to handle axial segregation by size for different superficial gas velocities and particle size distributions. 107 refs., 79 figs., 6 tabs.

  13. Parametric sensitivity analysis to investigate heptane reforming in circulating fast fluidized bed membrane reactors

    Directory of Open Access Journals (Sweden)

    M.E.E. Abashar

    2015-01-01

    Full Text Available In this paper, we present mathematical modeling and numerical simulation tools in searching the high parameter space of steam reforming of heptane for the key design parameters, which have the potential to give high heptane conversion, high hydrogen yield and hydrogen to carbon monoxide ratio within the industrial limits for the syngas used as a feedstock for the gas to liquid processes (GTL. The system under consideration is the novel circulating fast fluidized bed membrane reactor (CFFBMR. The simulation results show that the hydrogen membrane has a significant role in the displacement of the thermodynamic equilibriums of the reversible reactions and production of ultraclean hydrogen, which can be used as a fuel for the fuel cells. Also the results of the sensitivity analysis show that the best performance of the CFFBMR can be obtained by a proper selection of combination of several parameters of high feed temperatures, high steam to carbon feed ratios, high reaction side pressures coupled with a large permeation area of a composite thin film membrane. These parameters are interacting in a very complex manner to give 100% conversion of heptane and 496.94% increase in hydrogen yield compared to the reformer without hydrogen membrane. It was found that under these selected operating conditions a low H2/CO ratio of 1.15 is achieved satisfying the practical recommended industrial range.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  17. Particle descending velocity near the wall of a rolling circulating fluidized bed

    Science.gov (United States)

    Zhao, Tong; Takei, Masahiro; Murata, Hiroyuki; Liu, Kai

    2014-04-01

    As part of the study to develop compact and efficient marine exhaust gas treatment system with circulating fluidized bed (CFB), effects of the swing motion of a ship on gas-solid flow in the CFB was investigated. The heat transfer efficiency of the CFB is closely related with the particle flow near the wall of riser. As a trial to evaluate the particle flow near the wall of riser quantitatively, descending velocity of particles at upright and swing condition was measured by a particle image velocimetry (PIV) system. Particle motion near the wall of riser was recorded through an observation window by a high speed camera. The recorded images were processed to evaluate the local descending velocity of particles under different swing amplitude and period. As results, the swing motion affects the down-flow of particles, namely, descending particle flow along the wall of riser. The time-averaged descending velocity near the wall of riser is remarkably decreased by the motion. Effect of the swing period on the particle descending velocity is really small. But as the swing amplitude increases, the descending velocity of particle decreased significantly.

  18. Rapid pyrolysis of wheat straw in a Bench-Scale circulating Fluidized-Bed downer reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ding, T. [State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing (China); Graduate School of Chinese Academy of Sciences, Beijing (China); Li, S.; Xie, J.; Song, W.; Yao, J.; Lin, W. [State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing (China)

    2012-12-15

    The effects of acid washing treatment on the pyrolysis product distribution and product properties were investigated in a bench-scale circulating fluidized-bed (CFB) downer reactor with wheat straw as feedstock. The acid treatment not only removes most of the inorganic species present in the biomass but also alters the distribution of the remaining organic constituents. It was found that the removal of the inorganic species increases the yield of liquid product and reduces char formation and gas yield. CO and CO{sub 2} are the dominant components in the gaseous product, accounting for over 90 %. The concentration of CO in the gaseous product increases after acid treatment, while the CO{sub 2} concentration decreases. The oxygen and water contents in the liquid product are decreased on acid treatment, leading to a relatively high heating value and viscosity. More volatiles can be found in the char derived from the acid-treated wheat straw than from the raw wheat straw. This may suggest that a longer residence time is needed for pyrolysis of the acid-treated wheat straw in order to obtain the maximal yield of volatile matter. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Directory of Open Access Journals (Sweden)

    Balicki Adrian

    2014-06-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  1. EXPERIMENTAL RESEARCH OF FLOW STRUCTURE IN A GAS-SOLID CIRCULATING FLUIDIZED BED RISER BY PIV

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Particle Imaging Velocimetry (PIV) techniques were applied to investigate the particle motion and cluster properties in a gas-solid two-phase flow in a circulating fluidized bed riser. Visual images and micro-structure of various clusters were captured. After the boundary of clusters was determined by the gray level threshold method, clusters were classified by the distance between particles and the shape and position of clusters. In addition, the process of clusters forming and breaking up was described, and the sizes of clusters were also obtained. With the Minimum Quadric Difference (MQD) cross-correlation algorithm suitable for high-density particles, the axial velocities of the particles were obtained in the dilute phase section. The features of particle motion were revealed by investigating statistically the magnitude and distribution of particle axial velocity in the radial direction. At most radial cross-sections, there exists a parabola-shaped distribution of upward axial velocity of particles, namely, the magnitude of axial velocity in the core region is higher than that near the wall region of the riser.

  2. A New Solar Chemical Reactor with an Internally Circulating Fluidized bed for Direct Irradiation of Reacting Particles

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

    Solar thermochemical processes require the development of a high temperature solar reactor operating at 1000-1500 degree celsius, such as solar gasification of coal and the thermal reduction of metal oxides as part of a two-step water splitting cycle. Direct solar energy absorption by reacting particles of coal or metal oxides provides efficient heat transfer directly to the reaction site. The present paper describes a new type of the windowed solar chemical reactor directly illuminating reacting particles in an internally circulating fluidized bed. The reactor body is made of stainless steel having a quartz window on the top as aperture. A draft tube is centrally inserted in the fluidized bed region. Gases such as steam, CO2, or N2 are introduced into the draft tube and annulus regions in the bed separately. The concentrated solar radiation passes downwards TROUGH the window and directly heats the internally circulating fluidized bed of reacting particles. The prototype reactor was constructed in a laboratory scale and demonstrated on CO2 gasification of coal coke using solar-simulated, concentrated visible light from sun-simulator as the energy source. About 12% of the maximum chemical storage efficiency was obtained by the solar-simulated gasification of the coke. This new reactor will be also applied for a two-step water splitting cycle using redox metal-oxide particles. (Author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  4. Co-combustion of olive cake with lignite coal in a circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Aysel T. Atimtay; Huseyin Topal [Middle East Technical University, Ankara (Turkey). Department of Environmental Engineering

    2004-05-01

    In this study, olive cake (OC) was co-fired with coal in a circulating fluidized bed of 125 mm diameter and 1800 mm height. Olive cake is a waste from olive oil production. A lignite coal that is most widely used in Turkey (Tuncbilek lignite) was used together with OC and the combustion characteristics of olive cake (OC)+coal mixture were investigated. The combustion experiments were carried out with various excess air ratios. The excess air ratio, {lambda} has been changed between 1.1 and 2.16. Temperature distribution along the bed was measured with thermocouples. On-line concentrations of O{sub 2}, SO{sub 2}, CO{sub 2}, CO, NOx and total hydrocarbons were measured in the flue gas. Various runs were conducted with each mixture of OC and lignite, namely 25, 50 and 75 wt% OC mixed with lignite. These mixtures were burned with various excess air ratios. Combustion efficiencies of olive cake and lignite coal mixtures are calculated, and the optimum conditions for operating parameters are discussed. There is a sharp decrease observed in the combustion losses due to hydrocarbons and CO as the excess air ratio increases. The minimum emissions are observed at about {lambda} = 1.5. The combustion efficiency for lignite coal changes between 82 and 98% for various excess air ratios used in the study. The results suggest that OC is good fuel that can be mixed with lignite coal for cleaner energy production in small-scale industries by using CFB. Less than 50 wt% OC concentration in the fuel mixture is suggested in order to be within the EU limits for emissions. 11 refs., 12 figs., 7 tabs.

  5. Modeling and simulation of liquid-solid circulating fluidized bed ion exchange system for continuous protein recovery.

    Science.gov (United States)

    Mazumder, Jahirul; Zhu, Jingxu; Bassi, Amarjeet S; Ray, Ajay K

    2009-09-01

    Liquid-solid circulating fluidized bed (LSCFB) is an integrated two-column (downcomer and riser) system which can accommodate two separate processes (adsorption and desorption) in the same unit with continuous circulation of the solid particles between the two columns. In this study, a mathematical model based on the assumption of homogeneous fluidization was developed considering hydrodynamics, adsorption-desorption kinetics and liquid-solid mass transfer. The simulation results showed good agreement with the available experimental results for continuous protein recovery. A parametric sensitivity study was performed to better understand the influence of different operating parameters on the BSA adsorption and desorption capacity of the system. The model developed can easily be extended to other applications of LSCFB.

  6. Investigation of a dual-particle liquid-solid circulating fluidized bed bioreactor for extractive fermentation of lactic acid.

    Science.gov (United States)

    Patel, Manoj; Bassi, Amarjeet S; Zhu, Jesse J-X; Gomaa, Hassan

    2008-01-01

    A dual-particle liquid-solid circulating fluidized bed (DP-LSCFB) bioreactor has been constructed and investigated for the simultaneous production and extraction of lactic acid using immobilized Lactobacillus bulgaricus and ion-exchange resins. The apparatus consisted of a downer fluidized bed, 13 cm I.D. and 4.75 m tall, and a riser fluidized bed, 3.8 cm I.D. and 5.15 m in height. The lactic acid production and removal was carried out in the downer, while the riser was used for the recovery of lactic acid. A continuously recirculating bed of ion-exchange resin was used for adsorption of the produced acid as well as for maintaining optimum pH for bioconversion, thus eliminating the need for costly and complex chemical control approach used in conventional techniques. Studies using lactic acid aqueous solution as feed and sodium hydroxide solution as regeneration stream showed 93% lactic acid removal from the downer and 46% recovery in the riser under the conditions investigated. Such results prove the functionality of using the newly developed bioreactor design for the continuous production and recovery of products of biotechnological significance.

  7. Desulphurization in peat-fired circulating and bubbling fluidized bed boilers

    Energy Technology Data Exchange (ETDEWEB)

    Kouvo, P. [Imatran Voima Oy, Vantaa (Finland); Salmenoja, K. [Kvaerner Pulping Oy, Tampere (Finland)

    1997-12-31

    The new emission limit values for large combustion plants are under consideration both at the EU level and in Finland. Peat and wood are the only indigenous fuels of Finland. In 1995 appr. 8 % of electricity was produced with peat. The lower heating value of peat is around 10 MJ/kg. The moisture content varies between 35-55 % and sulphur content in dry solids between 0.15-0.35 %. The total peat power capacity of Finland in 1995 was 1400 MW. Because there was not enough information available about the desulphurization of the flue gases from peat-fired fluidized bed boilers, a group of Finnish companies and Ministry of Trade and Industry decided to carry out the full-scale desulphurisation study. In the project the desulphurization with limestone injection into the furnace of two types of peat-fired boilers were studied. The goal of the project was to investigate: what the technically and economically feasible emission level is by limestone injection in the fluidized bed combustion; how the limestone injection affects the other flue gas emissions and the fouling of the boiler and, what the economy of desulphurisation is. The tests were carried out at Kokkola and Kemi power plants in Finland. At Kokkola (108 MW{sub f}) circulating fluidized bed boiler, the emission limit of 200 mg/m{sup 3}n was leached at a Ca/S-molar ratio of appr. 10, with limestone containing 92 % of calcium carbonate, CaCO{sub 3}. At Kemi (267 MW{sub f}) bubbling fluidized bed boiler, the emission limit of 280 mg/m{sup 3}n with limestone containing appr. 95 % of CaCO{sub 3} was reached at a Ca/S-molar ratio of appr. 7.0. Emissions of NO{sub x}, N{sub 2}O, NH{sub 3} and dust after the ESP were not elevated due to the limestone feed. At the Kokkola power plant the NO{sub x} emissions varied from 300 to 400 mg/m{sup 3}n, and, at the Kemi power station the NO{sub x} emissions were around 200 mg/m{sup 3}n. The fouling of the Kemi boiler was found to be significant in the scheduled outage after the test

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Aubrey L. [WSU Research Corporation, Morgantown, WV (USA)

    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.

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

    Science.gov (United States)

    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.

  12. An Experimental Study of Liquid-Solid Flow in a Circulating Fluidized Bed of Varying Liquid Viscosity

    Directory of Open Access Journals (Sweden)

    nirmala sundaram

    2015-01-01

    Full Text Available Hydrodynamics plays a major role in the design of an industrial liquid-solid circulating fluidized bed (LSCFB system. Till date, research investigations have been carried out with tap water as a liquid phase in an LSCFB. But still there is a limited understanding regarding the circulation of particles in an LSCFB with viscous fluids. The aim of our study was to characterize the hydrodynamics in an LSCFB with varying viscosity. Experiments were conducted in a fluidized bed riser of 0.1 m diameter by 2.4 m height with different viscous liquids to study the effects of the operating parameters, namely, primary velocity, secondary velocity, and total velocity, on the hydrodynamic characteristics of the LSCFB with reference to its solid holdup, solid circulation rate, and particle velocity. Experiments were conducted using water and glycerol at different concentrations, and the solid particles (sand and resin of different densities, but same diameter were used in the experiment. The results indicate that the solid holdup in the riser was axially uniform for viscous liquids, which increased with an increase in auxiliary velocity. The average solid holdup decreased with an increase in total velocity, and it increased with an increase in liquid viscosity as the critical transitional velocity decreased with an increase in viscosity. The solid circulation rate was found to be increased with increased total velocity, auxiliary velocity, and viscosity.

  13. Application of Scaling-Law and CFD Modeling to Hydrodynamics of Circulating Biomass Fluidized Bed Gasifier

    Directory of Open Access Journals (Sweden)

    Mazda Biglari

    2016-06-01

    Full Text Available Two modeling approaches, the scaling-law and CFD (Computational Fluid Dynamics approaches, are presented in this paper. To save on experimental cost of the pilot plant, the scaling-law approach as a low-computational-cost method was adopted and a small scale column operating under ambient temperature and pressure was built. A series of laboratory tests and computer simulations were carried out to evaluate the hydrodynamic characteristics of a pilot fluidized-bed biomass gasifier. In the small scale column solids were fluidized. The pressure and other hydrodynamic properties were monitored for the validation of the scaling-law application. In addition to the scaling-law modeling method, the CFD approach was presented to simulate the gas-particle system in the small column. 2D CFD models were developed to simulate the hydrodynamic regime. The simulation results were validated with the experimental data from the small column. It was proved that the CFD model was able to accurately predict the hydrodynamics of the small column. The outcomes of this research present both the scaling law with the lower computational cost and the CFD modeling as a more robust method to suit various needs for the design of fluidized-bed gasifiers.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  15. Hydrodynamics in a Gas-solid Circulating Fluidized Bed%气-固循环流化床的流动特性

    Institute of Scientific and Technical Information of China (English)

    刘宝勇; 魏绪玲; 张斌; 杨西

    2012-01-01

    循环流化床是一种新型高效无气泡气-固反应器,应用广泛。文章首先介绍了气-固循环流化床的特点,总结了循环流化床上部区域的流动特性,并讨论了循环流化床底部区域的流动特性,最后展望了循环流化床流动特性研究的发展趋势。%Circulating fluidized bed is a new type high efficiency gas-solid reactor,without gas bubble,which is used widely.Characteristics of gas-solid circulating fluidized bed were introduced firstly.Then hydrodynamics in the upper zone of a circulating fluidized bed were summarized.Furthermore,hydrodynamics in the bottom zone of a circulating fluidized bed were discussed.At last,research tendency of hydrodynamics in circulating fluidized bed were prospected.

  16. Experimental Study of Stabilized Soil Utilizing Circulating Fluidized Bed Combustion Desulfurization Ash with Carbide Slag and Desulfurization Gypsum

    OpenAIRE

    2015-01-01

    This paper discusses the feasibility of preparing soil stabilizer which is circulating fluidized bed combustion ash-based, supplemented with carbide slag and desulfurization gypsum, composed entirely of complete industrial wastes. The results show that CFBC ash has better pozzolanic activity than fly ash. When stabilizer total content is 10% and the ratio of CFBC ash : carbide slag : desulfurization gypsum is 7.2 : 1.8 : 1, compressive strength of stabilized soil can reach the maximum of 2.12...

  17. Gas-solid two-phase flow in the riser of circulating fluidized beds: mathematical modelling and numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Cabezas Gomez, Luben; Milioli, Fernando Eduardo [Sao Paulo Univ., Sao Carlos, SP (Brazil). Escola de Engenharia. Nucleo de Engenharia Termica e Fluidos]. E-mails: lubencg@sc.usp.br; milioli@sc.usp.br

    2001-06-01

    A mathematical model is developed for gas-solids flows in circulating fluidized beds. An Eulerian formulation is followed based on the two-fluids model approach where both the fluid and the particulate phases are treated as a continuum. The physical modelling is discussed, including the formulation of boundary conditions and the description of the numerical methodology. Results of numerical simulation are presented and discussed. The model is validated through comparison to experiment, and simulation is performed to investigate the effects on the flow hydrodynamics of the solids viscosity. (author)

  18. Experimental study on the reuse of spent rapidly hydrated sorbent for circulating fluidized bed flue gas desulfurization.

    Science.gov (United States)

    Li, Yuan; Zheng, Kai; You, Changfu

    2011-11-01

    Rapidly hydrated sorbent, prepared by rapidly hydrating adhesive carrier particles and lime, is a highly effective sorbent for moderate temperature circulating fluidized bed flue gas desulfurization (CFB-FGD) process. The residence time of fine calcium-containing particles in CFB reactors increases by adhering on the surface of larger adhesive carrier particles, which contributes to higher sorbent calcium conversion ratio. The circulation ash of CFB boilers (α-adhesive carrier particles) and the spent sorbent (β and γ-adhesive carrier particles) were used as adhesive carrier particles for producing the rapidly hydrated sorbent. Particle physical characteristic analysis, abrasion characteristics in fluidized bed and desulfurization characteristics in TGA and CFB-FGD systems were investigated for various types of rapidly hydrated sorbent (α, β, and γ-sorbent). The adhesion ability of γ-sorbent was 50.1% higher than that of α-sorbent. The abrasion ratio of β and γ-sorbent was 16.7% lower than that of α-sorbent. The desulfurization abilities of the three sorbent in TGA were almost same. The desulfurization efficiency in the CFB-FGD system was up to 95% at the bed temperature of 750 °C for the β-sorbent.

  19. 21 CFR 890.5160 - Air-fluidized bed.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 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. Circulating fluidized bed boilers: Enhancing reagent utilization while maintaining proper SO{sub 2} removal

    Energy Technology Data Exchange (ETDEWEB)

    Buecker, B.; Wofford, J.; DuBose, R.; Ray, D.

    1998-07-01

    Circulating fluidized bed (CFB) combustion continues to be an emerging technology for a variety of reasons. The combustion chemistry and relatively low reaction temperature in the furnace minimize the production of sulfur and nitrogen oxides--both major pollutants of concern. In addition, CFBs can accommodate a wide variety of fuels, including those having low energy content, high sulfur, or both. Unit performance, and related operation and maintenance costs, is significantly affected by the sorbent selected for SO{sub 2} removal. While limestone is the typical reagent of choice, variations in limestone quality can have a dramatic impact on the reaction efficiency. The following article discusses the results of full-scale tests of high-quality limestone that were performed on the two, 50,000 lb/hr CFBs serving the University of North Carolina. The test were needed because the primary reagent being used at the facility was unreactive and caused ash handling problems. The report also discusses results from subsequent use of this better reagent. The test indicated that while limestone purity (CACO{sub 3} content) is an important factor in sorbent reactivity, crystalline structure and size distribution are just as important. The tests suggested that limestone consumption could be decreased by over 50% with the new stone. This conclusion was verified when the University began using the new stone on a permanent basis. Plant personnel were able to significantly reduce limestone costs and lower the amount of unreacted lime in the boiler ash. This latter item had caused problems with the public and environmental authorities, because clouds of water vapor were produced when the ash was wetted for hauling and disposal. Ash production volumes and the associated disposal costs were reduced as well. For present or prospective CFB managers, these results can easily justify the search for, and use of, limestones that otherwise would be considered too expensive or too distant from

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  2. Fluidized bed combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Kullendorff, A.; Wikner, J.

    1985-03-25

    The chamber is confined in a pressure vessel. The lower part of the chamber has tilted parallel gutters up to the height of the fluidized bed. The slope of the gutter walls is 5 degrees-15 degrees and the top area of the gutters is 1.3 to 3 times larger than their bottom.

  3. Research on the Gas Reburning in a Circulating Fluidized Bed (CFB System Integrated with Biomass Gasification

    Directory of Open Access Journals (Sweden)

    Changqing Dong

    2012-08-01

    Full Text Available N2O emissions from coal fired fluidized-bed combustion are approximately 30–360 mg/Nm3, much higher than that from pulverized coal combustion (less than 30 mg/Nm3. One approach to reduce the N2O is to reburn the biomass gasification gas in the coal-fired fluidized bed. In this paper, the effects of gasified biomass reburning on the integrated boiler system were investigated by both simulation and experimental methods. The simulation as well as experimental results revealed that the increase of the reburning ratio would decrease the theoretical air volume and boiler efficiency, while it would increase the fuel gas volume, combustion and exhuast gas temperature. The experimental results also indicated that the N2O removal could reach as high as 99% when the heat ratio of biomass gas to coal is 10.5%.

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

    Science.gov (United States)

    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.

  5. Analysis of the Development of Circulating Fluidized Bed at Home and Abroad%循环流化床国内外现状分析

    Institute of Scientific and Technical Information of China (English)

    王纯良

    2011-01-01

    This paper briefly summarized the current situation about the development of circulating fluidized bed at home and abroad, compared with the foreign circulating fluidized bed technology which has a large development trend, and investigated the prospects of circulating fluidized bed boiler technology in China.%本文主要对国内外循环流化床发展现状进行了简略的总结、归纳,并通过与国外循环流化床技术大型化、高参数的发展趋势对比,对我国循环流化床锅炉技术发展前景进行展望.

  6. Biparticle fluidized bed reactor

    Science.gov (United States)

    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.

  7. Oxygen Carrier Aided Combustion (OCAC of Wood Chips in a Semi-Commercial Circulating Fluidized Bed Boiler Using Manganese Ore as Bed Material

    Directory of Open Access Journals (Sweden)

    Magnus Rydén

    2016-11-01

    Full Text Available Oxygen Carrier Aided Combustion (OCAC is realized by using an active oxygen-carrying bed material in fluidized bed boilers. The active material is reduced in fuel rich parts of the boiler and oxidized in air rich parts. Advantages could be achieved such as new mechanisms for oxygen transport in space and time. Here calcined manganese ore has been used as active bed material in a 12 MWth circulating fluidized bed boiler. The fuel was wood chips and the campaign lasted more than two weeks. From an operational point of view, manganese ore worked excellently. From the temperature profile of the boiler it can be concluded that fuel conversion was facilitated, especially in the dense bottom bed. The effect did not always translate to reduced emissions, which suggests that final combustion in the cyclone outlet was also influenced. Substituting 10% of the sand bed with manganese ore made it possible to reduce the air to fuel ratio without generating large amounts of CO. The use of 100% manganese ore resulted in higher emissions of CO than the sand reference, but, when combined sulphur feeding, dramatic reductions in CO emissions, up to 90% compared to sand reference, was achieved.

  8. A measure of the degree of inhomogeneity in a distribution and its application in characterising the particle circulation in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Garncarek, Z. (Inst. of Mathematics, Pedagogical Univ. of Opole (Poland)); Przybylski, L. (Inst. of Tech., Pedagogical Univ. of Opole (Poland)); Botterill, J.S.M. (School of Chemical Engineering, Univ. of Birmingham (United Kingdom)); Bridgwater, J. (School of Chemical Engineering, Univ. of Birmingham (United Kingdom)); Broadbent, C.J. (School of Chemical Engineering, Univ. of Birmingham (United Kingdom))

    1994-09-01

    A quantitative method to evaluate variational processes such as particle circulation in a fluidized bed is presented. It involves the calculation of H, an index of the degree of inhomogeneity in the tracer circulation in standard measure. The position of a given particle in a rectangular fluidized bed was followed using Positron Emission Particle Tracking. This technique is able to locate a labelled solid and construct a three-dimensional trajectory of its movement. The degree of inhomogeneity in the tracer distribution was then calculated from the observations. The values of H for the tracer movement when the bed is operated with a differential air supply across the distributor to stimulate gross solids circulation, suggest that there are relatively large regions of the bed in which the presence of the tracer is much less frequent than elsewhere. This lack of homogeneity in the tracer particle circulation is consistent with visual observation of particle circulation in the investigated bed. Increase in H with increasing length of the duration of the test is consistent with a stable circulation pattern. H affords a quantitative measure of how the fluidized bed parameters influence the particles movement. (orig.)

  9. Theoretical investigations of the operating characteristics of circulating pressurized fluidized bed combustors; Theoretische Untersuchungen zum Betriebsverhalten zirkulierender Druckwirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, M.; Krumm, W.

    1999-07-01

    The combination of gas turbine and water-/steam cycle is a proper alternative to increase the efficiency of power plants. Coal fired power plants can be designed as reactors with pressurized coal gasification, pressurized coal dust combustion or a pressurized fluidized bed combustion to realize these plant design. Mathematical modeling and simulation are used to support the development of new power plant concepts, e.g. pressurized fluidized bed combustion. In this paper a one-dimensional model for a pressurized fluidized circulating bed combustion power plant is presented. The modeling structure allows to vary different parameters to identify the particular influence on the overall plant behavior. The model is enlarged by a more detailed balance for limestone. After describing the theoretical background of the influence of added limestone rate on the emissions of sulfurdioxide is shown. (orig.) [German] Ausgehend vom Prinzip eines Dampfkraftwerks mit atmosphaerischer Wirbelschichtfeuerung werden der Dampf- und Gasturbinenprozess bei den druckaufgeladenen Konzepten quasi parallel betrieben und die Gasturbine mit dem Rauchgas aus der Kohlenfeuerung beaufschlagt. Die wesentlichen Unterschiede zu erdgas- oder oelbefeuerten Kombianlagen sind bei den Druckwirbelschichtkonzepten, durch den in Zusammensetzung und Feuchtegehalt stark variierenden Brennstoff Kohle und durch die Auskopplung grosser Waermemengen bei der integrierten Dampferzeugung, gegeben. Der Hauptanteil der erzeugten elektrischen Leistung entfaellt auf den Dampfturbinenprozess. Druckwirbelschichtanlagen mit blasenbildender Wirbelschicht sind seit Anfang der 90er Jahre in Betrieb. Entsprechend der Entwicklung bei der atmopshaerischen Wirbelschichtfeuerung zeichnet sich als naechste Generation dieses Kraftwerkstyps die zirkulierende Druckwirbelschicht mit Heissgasfilter ab. Die mathematische Modellbildung hat sich zu einem anerkannten Werkzeug zur Unterstuetzung der Auslegung und der Untersuchung der Wirkung

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  11. Soy protein recovery in a solvent-free process using continuous liquid-solid circulating fluidized bed ion exchanger.

    Science.gov (United States)

    Prince, Andrew; Bassi, Amarjeet S; Haas, Christine; Zhu, Jesse X; Dawe, Jennifer

    2012-01-01

    Soy protein concentrates and soy protein isolates act as ingredients in bakery, meat and dairy products, baby formulas, starting materials for spun textured vegetable products, and other nutritional supplements. In this study, the effectiveness of a liquid-solid circulating fluidized bed (LSCFB) ion exchanger is demonstrated for the recovery of soluble soy proteins from full fat and defatted soy flour. Under steady-state operating conditions, about 50% of the proteins could be recovered from the feed streams entering the ion exchanger. The LSCFB was shown to be a promising system for the recovery of soy protein from both defatted and full fat soy flour solutions. As the ion exchange process captures dissolved proteins, the system may offer a less damaging form of processing compared with the acid precipitation process where soy protein aggregates form and functionality is affected. In addition, the LSCFB allows simultaneous adsorption and desorption of the proteins allowing for a continuous operation. No prefiltration of feed containing suspended particles is required as well, because fluidization is used in place of packed bed technology to improve on current ion exchange processes.

  12. High rate biological nutrient removal from high strength wastewater using anaerobic-circulating fluidized bed bioreactor (A-CFBBR).

    Science.gov (United States)

    Andalib, Mehran; Nakhla, George; Zhu, Jesse

    2012-08-01

    Biological nutrient removal (BNR) from high strength wastewater was investigated using a newly developed integrated anaerobic fluidized bed (AF) with circulating fluidized bed bioreactor henceforth called A-CFBBR. The A-CFBBR showed 99.7%COD removal, 84% nitrogen removal, with a very low sludge yield of 0.017 g VSS/g COD while treating a synthetic wastewater containing 10,700 mg COD/L and 250 mg NH(3)-N/L over a period of 6 months. The system was operated at an organic loading rate (OLR) of 35 kg COD/m(3)(AF) d and nitrogen loading rate (NLR) of 1.1 kg N/m(3)(CFBBR) d at a hydraulic retention time (HRT) of less than 12 h in the A-CFBBR. Microbial communities analysis using DGGE confirmed the presence of both AOBs and NOBs in the riser and downer. Pseudomonas putida and Pseudomonas fluorescence were the dominant denitrifiers present in the downer. Methanogenic activity was accomplished by a microbial mixture of archaea and bacteria in the anaerobic column.

  13. Combined cycle power plant with circulating fluidized bed combustion. Final report; Kombikraftwerk mit zirkulierender Druckwirbelschicht-Feuerung. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-05-01

    In the frame of this study the concept of a combined cycle power plant with circulating fluidized bed combustion was investigated for the application of national brown coal. The aims of this study which is subsidised by the FMTR are the following: - evaluation of the experiences which have been made so far in the frame of developing circulating fluidized bed combustion; - reaching of reliable statements about the process technology, about technical risks as well as about the time frame and the costs; - developing a task for a possible realisation of a 150 MW{sub el}-pilot plant in the new Laender. The present study shows that combined cycle power plants which are fuelled by brown coal can be realised according to the principle of circulating fluidized bed combustion with a plant net efficiency of 45% for a power of 150 MW{sub el} (pilot plant) and a plant net efficiency clearly above 47% for a power of 500 MW{sub el} (reference power plant). The combination of this efficient combined cycle power plant technology with a simple brown coal gasification module, that is integrated into a combustion reactor will almost certainly lead to plant net efficiencies of 50% and more, especially for ZDSWF plants of the second generation. (orig./GL) [Deutsch] Im Rahmen dieser Studie ist fuer den Einsatz einheimischer Braunkohle das Konzept eines Kombikraftwerkes auf der Basis der zirkulierenden Druckwirbelschichtfeuerung untersucht worden. Ziele dieser mit BMFT-Mitteln gefoerderten Studie sind: - die Bewertung der bisher im Rahmen der Entwicklung von Druckwirbelschichtfeuerungen gesammelten Erfahrungen, - die Gewinnung belastbarer Aussagen zum verfahrenstechnischen Konzept, zu technischen Risiken sowie zum Zeit- und Kostenrahmen sowie - die Ausarbeitung einer Aufgabenstellung fuer die moegliche Realisierung einer 150-MW{sub el}-Pilotanlage in den neuen Bundeslaendern. Die vorliegende Studie zeigt, dass mit Braunkohle befeuerte Kombikraftwerksanlagen nach dem Prinzip der

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

    Science.gov (United States)

    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 (bed temperature lower than 900 °C for fuels with low volatiles content (circulating ash, the efficiency of SNCR could reach as high as 70%. The Hg emission of CFB is very low for the new NER due to its innate property.

  15. Discussion on abnormal returning feed of circulating fluidized bed boiler%循环流化床锅炉返料异常原因探讨

    Institute of Scientific and Technical Information of China (English)

    张帅

    2015-01-01

    The author analyzed abnormal returning feed of circulating fluidized bed boiler and the result of lowering load which was forced by the problems.%本文分析了锅炉返料系统异常造成机组被迫降负荷运行的现象原因及解决措施。

  16. Experimental Study of Stabilized Soil Utilizing Circulating Fluidized Bed Combustion Desulfurization Ash with Carbide Slag and Desulfurization Gypsum

    Directory of Open Access Journals (Sweden)

    Dezhi Shao

    2015-01-01

    Full Text Available This paper discusses the feasibility of preparing soil stabilizer which is circulating fluidized bed combustion ash-based, supplemented with carbide slag and desulfurization gypsum, composed entirely of complete industrial wastes. The results show that CFBC ash has better pozzolanic activity than fly ash. When stabilizer total content is 10% and the ratio of CFBC ash : carbide slag : desulfurization gypsum is 7.2 : 1.8 : 1, compressive strength of stabilized soil can reach the maximum of 2.12 MPa at the age of 28 d of curing. Stabilizer can meet the strength requirements of cement-soil mixing pile composite foundation and cement-soil mixing pile waterproof curtain.

  17. Experimental and mechanism studies on simultaneous desulfurization and denitrification from flue gas using a flue gas circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi; XU PeiYao; SUN XiaoJun; WANG LiDong

    2007-01-01

    The oxidizing highly reactive absorbent was prepared from fly ash, industry lime, and an oxidizing additive M. Experiments of simultaneous desulfurization and denitrification were carried out in a flue gas circulating fluidized bed (CFB). The effects of influencing factors and calcium availability were also investigated on the removal efficiencies of desulfurization and denitrification. Removal efficiencies of 95.5% for SO2 and 64.8% for NO were obtained respectively under the optimal experimental conditions. The component of the spent absorbent was analyzed with chemical analysis methods. The results indicated that more nitrogen species appeared in the spent absorbent except sulfur species. A scanning electron microscope (SEM) and an accessory X-ray energy spectrometer were used to observe micro-properties of the samples, including fly ash, oxidizing highly reactive absorbent and spent absorbent. The simultaneous removal mechanism of SO2 and NO based on this absorbent was proposed according to the experimental results.

  18. Hydrogen production by steam reforming of higher hydrocarbons in a novel circulating fluidized bed reactor-regenerator system

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.; Elnashaie, S.; Yan, Y. [Auburn Univ., AL (United States). Dept. of Chemcial Engineering

    2003-07-01

    A mathematical model was developed to demonstrate the production of hydrogen by steam reforming of higher hydrocarbons in a circulating fluidized bed reactor-regenerator system (CFBRR). Heptane was the higher hydrocarbon used in this study. The process simulation of the riser steam reformer, catalyst regenerator, and downer indicate that the impact of catalyst deactivation is negligible because of the large mass flow ratio of solid to gas stream and the catalyst regenerator. The carbon deposited on the catalyst can be either gasified efficiently in the steam reformer or burned with air in the catalyst regenerator. The burning of carbon on the catalyst supplies the heat required for endothermic steam reforming of heptane and methane. This method has potential advantages for both energy consumption as well as hydrogen production.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  1. A circulating fluidized bed combustor system with inherent CO{sub 2} separation : application of chemical looping combustion

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, E.; Lyngfelt, A.; Mattisson, T.; Johnsson, F. [Chalmers Univ. of Technology, Goteborg (Sweden). Dept. of Energy Conversion

    2002-07-01

    This paper presents a method to achieve carbon dioxide-free combustion while still using fossil fuels as the energy source. The method is based on separation and disposal of carbon dioxide from combustion. Chemical looping combustion (CLC) uses metal oxide particles to transfer oxygen from air to a gaseous fuel. The gaseous fuel is combusted with inherent separation of carbon dioxide (a greenhouse gas) from the flue gas. A bubbling bed below the downcomer in the circulating fluidized bed acts as a fuel reactor where oxygen is transferred from the metal oxide to the fuel. The riser acts as the air reactor where the oxygen from the air oxidizes the previously reduced metal oxide. The fuel and combustion air are not in direct contact. The conceptual design of the pressurized CLC system was examined in order to map suitable conditions for the riser and to achieve sufficient net solids flux between the reactors and the bed mass in the riser. A range of possible operating conditions were suggested. The operating conditions depend on the reaction properties of the oxygen carriers. 16 refs., 1 tab., 8 figs.

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

    Science.gov (United States)

    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.

  3. Virtual experimentation through 3D full-loop simulation of a circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Eulerian granular multiphase model with a drag coefficient correction based on the energy-minimization multi-male (EMMS) model was used to simulate a semi-industry scale circulating fiuidized bed (CFB).Three-dimensional(3D), time-dependent simulation of a full-loop CFB revealed that the axial profiles of cross-sectionally averaged solid volume fraction,and the radial profiles of solid axial velocity and solid volume fraction were in reasonable agreement with experimental data.Based on this agreement,database derived from experiments not yet accomplished was replenished with such simulations, and fluid regime diagrams and pressure balance around the CFB loop were derived accordingly. This work presents an integrated viewpoint on CFB and unfolds a fresh paradigm fur CFB modeling, which can be expected to help resolve certain issues long in dispute but hard for experiments.

  4. Recent Progress in the Study of Circulating Fluidized Bed Hydrodynamics%循环流化床流体动力学研究进展

    Institute of Scientific and Technical Information of China (English)

    朱廷钰; 肖云汉

    2001-01-01

    论述了国内外在循环流化床流体动力学研究领域的进展,对循环流态化颗粒流动问题、颗粒聚集及传热以及循环流态化数学模型等热点问题进行了重点回顾,并指出了当前循环流化床流体动力学研究的一些新动向。%Discussed in this paper is the recent progress in the study both at home and abroad of circulating fluidized bed hydrodynamics. The overview has been focused on a variety of hot topics, such as the problem of circulating fluidized particle flow, particle agglomeration and heat transfer, and a circulating fluidization mathematical model, etc. In addition, some new development trends have been highlighted in the current study of circulating fluidized bed hydrodynamics

  5. 300 MW circulating fluidized bed boiler combustion control algorithms%300MW循环流化床锅炉燃烧控制算法研究

    Institute of Scientific and Technical Information of China (English)

    熊彬; 潘维加

    2013-01-01

      Circulating fluidized bed boiler is a distribution parameters,nonlinear,time varying delay, multivariate tight coupling of the controlled object,the conventional control method,it is hard to obtain the ideal control effect..Combined with a domestic 300 Mw circulating fluidized bed boiler,analysis of the circulating fluidized bed boiler control characteristics and control methods,combined with circulating fluidized bed boiler dynamic mathematical model,and puts forward some self-organizing fuzzy neural network of CFB system control method,and the adaptive particle swarm algorithm to optimize the simulation results. The control system can effectively solve the circulating fluidized bed boiler control of the difficulties, has obtained the satisfactory control effect.Finally,the development direction of circulating fluidized bed boiler is discussed and forecast.%  循环流化床锅炉是一个分布参数、非线性、时变、大滞后、多变量紧密耦合的被控对象,常规控制方法难以取得理想的控制效果。结合国内某300 Mw循环流化床锅炉,分析循环流化床锅炉的控制特点和控制方法,结合循环流化床锅炉动态数学模型,提出自组织模糊神经网络的CFB系统控制方法,并用自适应粒子群算法对仿真结果进行优化。该控制系统有效地解决了循环流化床锅炉控制中的难点问题,取得了满意的控制效果。最后对循环流化床锅炉的发展方向进行了探讨和预测。

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

    Science.gov (United States)

    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.

  7. Characterization of ashes from a 100 kWth pilot-scale circulating fluidized bed with oxy-fuel combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.H.; Wang, C.B.; Tan, Y.W.; Jia, L.F.; Anthony, E.J. [Natural Resources Canada, Ottawa, ON (Canada)

    2011-09-15

    Oxy-fuel combustion experiments have been carried out on an oxygen-fired 100 kW(th) mini-circulating fluidized bed combustion (CFBC) facility. Coal and petroleum coke were used as fuel together with different limestones (and fixed Ca:S molar ratios) premixed with the fuel, for in situ SO{sub 2} capture. The bed ash (BA) and fly ash (FA) samples produced from this unit were collected and characterized to obtain physical and chemical properties of the ash samples. The characterization methods used included X-ray fluorescence (XRF), X-ray diffraction (XRD), char carbon and free lime analysis, thermogravimetric analysis (TGA), and surface analysis. The main purpose of this work is to characterize the CFBC ashes from oxy-fuel firing to obtain a better understanding of the combustion process, and to identify any significant differences from the ash generated by a conventional air-fired CFBC. The primary difference in the sulfur capture mechanism between atmospheric air-fired and oxy-fuel FBC, at typical FBC temperatures (similar to 850{sup o}C), is that, in the air-fired case the limestone sorbents calcine, whereas the partial pressure of CO{sub 2} in oxy-fuel FBC is high enough to prevent calcination, and hence the sulfation process should mimic that seen in pressurized FBC (PFBC). Here, the char carbon content in the fly ash was much higher than that in the bed ash, and was also high by comparison with ash obtained from conventional commercial air-firing CFBC units. In addition, measurements of the free lime content in the bed and fly ash showed that the unreacted Ca sorbent was present primarily as CaCO{sub 3}, indicating that sulfur capture in the oxy-fuel combustor occurred via direct sulfation.

  8. Pyrolysis of high-ash sewage sludge in a circulating fluidized bed reactor for production of liquids rich in heterocyclic nitrogenated compounds.

    Science.gov (United States)

    Zuo, Wu; Jin, Baosheng; Huang, Yaji; Sun, Yu; Li, Rui; Jia, Jiqiang

    2013-01-01

    A circulating fluidized bed reactor was used for pyrolyzing sewage sludge with a high ash content to produce liquids rich in heterocyclic nitrogenated compounds. GC/MS and FTIR analyses showed that heterocyclic nitrogenated compounds and hydrocarbons made up 38.5-61.21% and 2.24-17.48% of the pyrolysis liquids, respectively. A fluidized gas velocity of 1.13 m/s, a sludge feed rate of 10.78 kg/h and a particle size of 1-2mm promoted heterocyclic nitrogenated compound production. Utilizing heterocyclic nitrogenated compounds as chemical feedstock could be a way for offsetting the cost of sewage sludge treatment.

  9. Modelling of Devolatilization in Fluidized Bed Combustion

    DEFF Research Database (Denmark)

    Stenseng, Mette; Lin, Weigang; Johnsson, Jan Erik

    1997-01-01

    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 hea...

  10. VOC emission control by circulating fluidized bed adsorption; Controle de l'emission de composes organiques volatils par adsorption en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Song, W.

    2003-12-15

    This work deals with the circulating fluidized bed technology, applied to the elimination by adsorption of volatile organic compounds (VOCs), like toluene, in a gas flow. In the process, the adsorbent (millimetric spherical grains of micro-porous carbon) is moved by a strong flow rate of gas inside a vertical tube without lining. Mass and heat transfers are very important and important volumes of compounds can be processed. This work presents the determination of the adsorption equilibrium, the description of the experimental facility and of the results of experiments, the development of an original model of the process which combines a flow model and a mass transfer model, a parametric study of this model, and finally, some extensions of the process principle to staged operations with pressure variation or temperature variation cycles. (J.S.)

  11. Experimental study on fuel oil combustion in circulating fluidized bed; Estudio experimental sobre la combustion de combustoleo en lecho fluidizado circulante

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Rangel, Ricardo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    The Instituto de Investigaciones Electricas (IIE) developed a circulating fluidized bed combustor of 0.5 thermal MW unique in its type in Latin America. The Bachelor`s thesis entitled ``Experimental Study on Fuel Oil Combustion in Circulating Fluidized Bed`` was performed operating this combustor with the purpose of determining the feasibility of burning heavy fuel oil in a stable and sustained form, as well as the effect of the addition of calcium carbonate to the combustor. The results of the experimental trials showed heavy fuel oil can be burned in a circulating fluidized bed, with low sulfur dioxide emissions. During the conduction of the experiments a sulfur retention of 43% was achieved with a Ca/S relationship of 4.5. [Espanol] El Instituto de Investigaciones Electricas (IIE) desarrollo un combustor de lecho fluidizado circulante de 0.5 MW termicos de potencia, unico en su tipo en Latinoamerica. La tesis de licenciatura titulada Estudio Experimental sobre la Combustion de Combustoleo en Lecho Fluidizado Circulante se realizo operando dicho combustor, con el proposito de determinar la factibilidad de quemar combustoleo pesado en forma estable y autosostenida, asi como la influencia que tiene la adicion de carbonato de calcio al lecho. Los resultados de los ensayos experimentales mostraron que se puede quemar combustoleo pesado en un lecho fluidizado circulante, con bajas emisiones de bioxido de azufre. Durante la experimentacion se logro una retencion de azufre del 43%, con una relacion Ca/S de 4.5.

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

    Directory of Open Access Journals (Sweden)

    Seehyung Lee

    2012-01-01

    Full Text Available 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.

  13. Co-firing of pine chips with Turkish lignites in 750kWth circulating fluidized bed combustion system.

    Science.gov (United States)

    Atimtay, Aysel T; Kayahan, Ufuk; Unlu, Alper; Engin, Berrin; Varol, Murat; Olgun, Hayati; Atakul, Husnu

    2017-01-01

    Two Turkish lignites which have different sulfur levels (2-2.9% dry) and ash levels (17-25% dry) were combusted with a Turkish forest red pine chips in a 750kW-thermal capacity circulating fluidized bed combustor (CFBC) system. The combustion temperature was held at 850±50°C. Flue gas emissions were measured by Gasmet DX-4000 flue gas analyzer. Two lignites were combusted alone, and then limestone was added to lignites to reduce SO2 emissions. Ca/S=3 was used. 30% percent of red pine chips were added to the lignites for co-firing experiments without limestone in order to see the biomass effects. The results showed that with limestone addition SO2 concentration was reduced below the limit values for all lignites. CO emissions are high at low excess air ratios, gets lower as the excess air ratio increases. During co-firing experiments the temperature in the freeboard was 100-150°C higher as compared to coal combustion experiments.

  14. Experimental and mechanism studies on simultaneous desulfurization and denitrification from flue gas using a flue gas circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The oxidizing highly reactive absorbent was prepared from fly ash,industry lime,and an oxidizing additive M.Experiments of simultaneous desulfurization and denitrification were carried out in a flue gas circulating fluidized bed(CFB).The effects of influencing factors and calcium availability were also investigated on the removal efficiencies of desulfurization and denitrification.Removal efficiencies of 95.5%for SO2 and 64.8%for NO were obtained respectively under the optimal experimental conditions. The component of the spent absorbent was analyzed with chemical analysis methods.The results in- dicated that more nitrogen species appeared in the spent absorbent except sulfur species.A scanning electron microscope(SEM)and an accessory X-ray energy spectrometer were used to observe micro-properties of the samples,including fly ash,oxidizing highly reactive absorbent and spent absorbent.The simultaneous removal mechanism of SO2 and NO based on this absorbent was pro- posed according to the experimental results.

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Chang-Sang Cho

    2012-01-01

    Full Text Available 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.

  17. Feasibility study on solidification of municipal solid waste incinerator fly ash with circulating fluidized bed combustion coal fly ash.

    Science.gov (United States)

    Liu, Wenshi; Hou, Haobo; Zhang, Chuhao; Zhang, Dajie

    2009-05-01

    The objective of this study was to assess the feasibility of solidification of municipal solid waste incinerator (MSWI) fly ash with circulation fluidized bed combustion (CFBC) fly ash, which is unsuitable as a cement replacement due to its high amounts of carbon, lime and anhydrite. The solidification process was conducted on samples prepared from MSWI fly ash, binders (cement clinkers and CFBC fly ash were mixed at two replacement ratios) and water (water/solid weight ratio = 0.4), among which the MSWI fly ash replaced each binder at the ratio of 0, 20, 40, 60 and 80% by dry weight. The samples were subjected to compressive strength tests and Toxicity Characteristic Leaching Procedure and the results showed that all solidified MSWI fly ash can meet the landfill standard imposed by US EPA after 28 days of curing. Micro-analysis (X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrophotometry) revealed that the main hydrate products were C-S-H gel and ettringite, which have a positive effect on heavy metals retention. Therefore, this method provides a possibility to achieve a cheap and effective solution for MSWI fly ash management and use for CFBC fly ash.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    Science.gov (United States)

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

    2004-12-15

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  4. Emission characteristics of co-combustion of sewage sludge with olive cake and lignite coal in a circulating fluidized bed.

    Science.gov (United States)

    Toraman, Oner Yusuf; Topal, Hüseyin; Bayat, Oktay; Atimtay, Aysel T

    2004-01-01

    In this study, a circulating fluidized bed (CFB) of 125 mm diameter and 1800mm height was used to find the combustion characteristics of sewage sludge (SS) produced in Turkey. Sludge + olive cake, and sludge + lignite coal mixtures were burned separately. Various sludge-to-lignite coal and sludge-to-olive cake ratios (5/95, 10/90, 15/85, 20/80) were tried. On-line concentrations of major components (O2, SO2, CO2, CO, NOx, CmHn) were measured in the flue gas, as well as temperature and pressure distributions along the bed. Combustion efficiencies of sludge + olive cake and sludge + lignite coal mixtures were calculated, and the optimum conditions for operating parameters were discussed. The results have shown that the combustion mainly takes place in the upper regions of the main column where the temperature reaches 900 degrees C. SS + Coal burn in the CFB with an efficiency of 95.14% to 96.18%, which is considered to be quite good. When burning sludge mixed with olive cake, appreciable amounts of CO and unburned hydrocarbons are formed and the combustion efficiency drops to 92.93%. CO and CmHn emissions are lower when lignite coal is mixed with various amounts of SS than the emissions when the coal is burned alone. As the %SS is increased in the fuel mixture, the SO2 emission decreases. NOx emissions are slightly higher. When burning sludge mixed with olive cake, SO2 and NOx emissions are slightly higher. CO and CmHn emissions decrease sharply when SS is mixed with 5%wt. olive cake. With increasing sludge ratio these emissions increase due to the unburned hydrocarbons. As a result of this study, it is believed that SS can be burned effectively in a CFBC together with other fuels, especially with olive cake (OC). OC will be a good additive fuel for the combustion of lower quality fuels.

  5. Investigation on Horizontal Mixing of Particles in Dense Bed in Circulating Fluidized Bed(CFB)

    Institute of Scientific and Technical Information of China (English)

    XiaoPing; YanGuizhang; 等

    1998-01-01

    A two dimensional cold CFB test rig has been established.investigation on horizontal mixing of particles in dense bed has been caried out on this test rig.Miaing model has been used in data reduction,the horizontal mixing coefficients of particles in different experimental conditions and in different structures of dense bed have been obtained and compared.By using dimensional analysis,non-dimensional expression of experimental condition and mixing coefficient have been obtained.

  6. Dual Fluidized Bed Biomass Gasification

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-09-30

    The dual fluidized bed reactor is a recirculating system in which one half of the unit operates as a steam pyrolysis device for biomass. The pyrolysis occurs by introducing biomass and steam to a hot fluidized bed of inert material such as coarse sand. Syngas is produced during the pyrolysis and exits the top of the reactor with the steam. A crossover arm, fed by gravity, moves sand and char from the pyrolyzer to the second fluidized bed. This sand bed uses blown air to combust the char. The exit stream from this side of the reactor is carbon dioxide, water and ash. There is a second gravity fed crossover arm to return sand to the pyrolysis side. The recirculating action of the sand and the char is the key to the operation of the dual fluidized bed reactor. The objective of the project was to design and construct a dual fluidized bed prototype reactor from literature information and in discussion with established experts in the field. That would be appropriate in scale and operation to measure the relative performance of the gasification of biomass and low ranked coals to produce a high quality synthesis gas with no dilution from nitrogen or combustion products.

  7. Pulsed atmospheric fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

  9. Simulation of emission performance and combustion efficiency in biomass fired circulating fluidized bed combustors

    Energy Technology Data Exchange (ETDEWEB)

    Gungor, Afsin [Nigde University, Faculty of Engineering and Architecture, Department of Mechanical Engineering, 51100 Nigde (Turkey)

    2010-04-15

    In this study, the combustion efficiency and the emission performance of biomass fired CFBs are tested via a previously published 2D model [Gungor A. Two-dimensional biomass combustion modeling of CFB. Fuel 2008; 87: 1453-1468.] against two published comprehensive data sets. The model efficiently simulates the outcome with respect to the excess air values, which is the main parameter that is verified. The combustion efficiency of OC changes between 82.25 and 98.66% as the excess air increases from 10 to 116% with the maximum error of about 8.59%. The rice husk combustion efficiency changes between 98.05 and 97.56% as the bed operational velocity increases from 1.2 to 1.5 m s{sup -1} with the maximum error of about 7.60%. CO and NO{sub x} emissions increase with increasing bed operational velocity. Increasing excess air results in slightly higher levels of NO{sub x} emission. A significant amount of combustion occurs in the upper zone due to the high volatile content of the biomass fuels. (author)

  10. Emission characteristics of co-combustion of sewage sludge with olive cake and lignite coal in a circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Toraman, O.Y.; Topal, H.; Bayat, O.; Atimtay, A.T. [Middle East Technical University, Ankara (Turkey). Dept. of Environmental Engineering

    2004-07-01

    In this study, a circulating fluidized bed (CFB) of 125 mm diameter and 1800 trim height was used to find the combustion characteristics of sewage sludge (SS) produced in Turkey. Sludge + olive cake, and Sludge + lignite coal mixtures were burned separately. Various sludge-to-lignite coal and sludge-to-olive cake ratios (5/95, 10/90. 15/85, 20/80) were tried. On-line concentrations of major components (O{sub 2}, SO{sub 2}, CO{sub 2}, CO, NOx, C{sub m}H{sub n}) were measured in the flue gas, as well as temperature and pressure distributions along the bed. Combustion efficiencies of sludge + olive cake and sludge + lignite coal mixtures were calculated, and the optimum conditions for operating parameters were discussed. The results have shown that the combustion mainly takes place in the upper regions of the main column where the temperature reaches 900 C. SS + coal burn in the CFB with an efficiency of 95.14% to 96.18%, which is considered to be quite good. When burning sludge mixed with olive cake, appreciable amounts of CO and unburned hydrocarbons are formed and the combustion efficiency drops to 92.93%. CO and C{sub m}H{sub n} emissions are lower when lignite coal is mixed with various amounts of SS than the. emissions when the coal is burned alone. As the %SS is increased in the fuel mixture, the SO{sub 2} emission decreases. NOx emissions are slightly higher. When burning sludge mixed with olive cake, SO{sub 2} and NOx emissions are slightly higher. CO and C{sub m}H{sub n} emissions decrease sharply when SS is mixed with 5%wt. olive cake. With increasing sludge ratio these emissions increase due to the unburned hydrocarbons. As a result of this study, it is believed that SS can be burned effectively in a CFBC together with other fuels, especially with olive cake (OC). OC will be a good additive fuel for the combustion of lower quality fuels.

  11. Characteristics of fluidized-packed beds

    Science.gov (United States)

    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. Experimental findings on thermal use of residues and biofuels in circulating fluidized bed combustion systems; Experimentelle Ergebnisse zur thermischen Nutzung von Rest- und Biobrennstoffen in zirkulierenden Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W.; Brunne, T.; Girndt, H. [Technische Univ. Dresden (Germany); Albrecht, J. [Lurgi Lentjes Babcock, Frankfurt am Main (Germany); Youssef, M. [Minia Univ. (Egypt)

    1996-12-31

    The energy Engineering Institute of Dresden Technical University investigated the combustion and emission characteristics of a number of combustion systems, including a circulating fluidized bed system with a capacity of 0.3 MW{sub th}. Egypt`s sugar cane industry produces large volumes of bagasse. The conbustion and emission characteristics of this biofuel in a circulating fludized bed combustion systems were investigated in a joint research project of the University of Minia and Dresden Technical University. (orig.) [Deutsch] Am Institut fuer Energietechnik der TU Dresden wird das Verbrennungs- und Emissionsverhalten verschiedenster Brennstoffe in unterschiedlichen Feuerungssystemen untersucht. Neben anderen Pilotanlagen steht eine zirkulierende Wirbelschichtfeuerung (ZWFS) mit einer Leistung von 0.3 MW{sub th} zur Verfuegung. In der Zuckerrohrindustrie Aegyptens fallen grosse Mengen von Bagasse an. In einer gemeinsamen Forschungsarbeit zwischen der Universitaet Minia und der TU Dresden sollte das Verbrennungs- und Emissionsverhalten dieses Biobrennstoffes in einer ZWSF untersucht werden. (orig)

  13. Operation Characteristics of Fluidized Bed Heat Exchanger of Large-scale Circulating Fluidized Bed Boiler%大型循环流化床锅炉外置换热器运行特性分析

    Institute of Scientific and Technical Information of China (English)

    张缦; 吴海波; 孙运凯; 吕清刚

    2012-01-01

    为掌握大型循环流化床(circulating fluidized bed,CFB)锅炉外置换热器(fluidized bed heat exchanger,FBHE)的运行特性,在2台实际运行的300MW CFB锅炉上进行了运行特性测试研究,包括FBHE对CFB锅炉床温、汽温的调节及其传热特性的研究。结果表明:带FBHE的CFB锅炉炉膛温度沿炉膛高度分布比较均匀,且在60%锅炉最大连续蒸发量(boiler maximum continue rate,BMCR)以上运行时床温无明显变化,而无FBHE的CFB锅炉床温随负荷变化明显,炉膛温度沿炉膛高度差别较大,且随着锅炉负荷的降低,差别更明显;锥型阀的开度随锅炉负荷的增加而增大;在负荷不变的情况下,过热器的喷水量和再热器的吸热量随床温的升高递减,但减少幅度较小;不同负荷下FBHE内不同受热面的传热系数不同,其值均随负荷的增加单调增大。%In order to investigate the operation characteristics of fluidized bed heat exchanger(FBHE) of large-scale circulating fluidized bed(CFB) boiler,experiments were conducted on two 300 MW CFB boilers which have been put into commercial operation,including the effect of FBHE on the adjustment characteristics of furnace temperature and steam temperature of CFB boiler and heat transfer characteristics of FBHE.The results indicate that the furnace temperature of CFB boiler with FBHE is quite even along the height direction,and there is almost no change in temperature when the boiler operates at above 60% boiler maximum continue rate(BMCR),whereas the furnace temperature of CFB boiler without FBHE is quite different,such difference becomes more obvious with the boiler load decreasing.The opening of cone valve increases monotonously along with the boiler load increasing.In the condition of constant load,when the bed temperature rises superheater water spray and reheater heat absorption decreases but at a relatively low degree.At different boiler loads,the heat transfer coefficients of

  14. Rapid ignition of fluidized bed boiler

    Science.gov (United States)

    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.

  15. Fluidization of potato starch in a stirred vibrating fluidized bed

    NARCIS (Netherlands)

    Kuipers, N.J M; Stamhuis, Eize; Beenackers, A.A C M

    1996-01-01

    A novel gas-solid reactor for cohesive C-powders such as potato starch is introduced, designed and characterized, the so-called stirred vibrating fluidized bed. The effects of a sinusoidal vibration of the gas distributor and/or stirring of the bed are investigated. The fluidization index, bed expan

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Agglomeration-Free Distributor for Fluidized Beds

    Science.gov (United States)

    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.

  18. Gas-solid flow field numerical simulation of different feeding and returning formations of flue-gas circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    WANG Hu

    2012-01-01

    3D Euler double-fluid model was applied and three different feedstocks and reverts formations were simulated.By calculating and analyzing the state of gas and solid fluxion in absorber using three different methods of the feedstocks and reverts in recirculating fluidized bed,described the behavior of gas and solid through the gas-phase velocity,turbulence intensity,gas-solid sliding velocity,and density of particles.The results show that the feedstocks and reverts enters into absorption tower through two symmetrical feedings and are mixed with flue gas.Based on the respective analysis of each model and the comparison analysis of the three models,this paper drew conclusions.The turbulence intensity of absorption tower is high,gas-solid sliding speed is big,and granule concentration near the axis is high,which has advantages for desulfurization and improving the utilization rate of absorbent.

  19. Anaerobic degradation of purified terephthalic acid wastewater using a novel, rapid mass-transfer circulating fluidized bed.

    Science.gov (United States)

    Feng, Yangyang; Lu, Beibei; Jiang, Yu; Chen, Yinwen; Shen, Shubao

    2012-01-01

    The anaerobic treatability of purified terephthalic acid (PTA) wastewater in a novel, rapid mass-transfer fluidized bed reactor using brick particles as porous carrier materials was investigated. The reactor operation was stable after a short 34 day start-up period, with chemical oxygen demand (COD) removal efficiency between 65 and 75%, terephthalate (TA) removal efficiency between 60% and 70%, and system organic loading rate (OLR) increasing from 7.37 to 18.52 kg COD/m(3) d. The results demonstrate that the reactor is very efficient, and requires a low hydraulic retention time (HRT) of 8 h to remove both TA and COD from the high-concentration PTA wastewater. The system also has high resistance capacity to varied OLR.

  20. The influence of the gas-distributing grid diameter on the transition velocity and hydrodynamics of the bottom layer in circulating fluidized bed installations

    Science.gov (United States)

    Tuponogov, V. G.; Baskakov, A. P.

    2013-11-01

    The dependences of dimensionless fluidization velocities separating bubble, transition, and fast fluidization regimes on the properties of dispersed material for particles belonging to groups B and D (according to D. Geldart's classification) are presented. Correspondence between the considered dependences and experimental data obtained by different researchers and their correlation with critical fluidization velocities and particle terminal velocities are shown. The hydrodynamic mechanisms governing the saturation of fluidized bed with bubbles on reaching the transition fluidization velocity in installations having different sizes are considered. Factors due to which a bottom bubble layer disappears in narrow installations and is retained on large-diameter grids in an intense channel forming mode are explained. Experimental data are presented from which it is seen that the bubble layer hydrodynamics depends on the gas-distributing grid diameter and that this diameter has an insignificant influence on the fluidization velocity during the transition from a bubble to fast fluidization regime.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

  5. Fluidized bed coal combustion reactor

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Perspectives for Fluidized Bed Nuclear Reactor Technology using Rotating Fluidized Beds in a Static Geometry

    Science.gov (United States)

    Broqueville, Axel De; Wilde, Juray De

    The new concept of a rotating fluidized bed in a static geometry opens perspectives for fluidized bed nuclear reactor technology and is experimentally and numerically investigated. With conventional fluidized bed technology, the maximum attainable power is rather limited and maximum at a certain fluidization gas flow rate. Using a rotating fluidized bed in a static geometry, the fluidization gas drives both the centrifugal force and the counteracting radial gas-solid drag force in a similar way. This allows operating the reactor at any chosen sufficiently high solids loading over a much wider fluidization gas flow rate range and in particular at much higher fluidization gas flow rates than with conventional fluidized bed reactor technology, offering increased flexibility with respect to cooling via the fluidization gas. Furthermore, the centrifugal force can be a multiple of earth gravity, allowing radial gas-solid slip velocities much higher than in conventional fluidized beds. The latter result in gas-solid heat transfer coefficients one or multiple orders of magnitude higher than in conventional fluidized beds. The combination of dense operation and high fluidization gas flow rates allows process intensification and a more compact reactor design.

  8. 气-液-固三相循环流化床中的液相轴向扩散%Axial Liquid Dispersion in Gas-Liquid-Solid Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    M. Vatanakul; 孙国刚; 郑莹; M. Couturier

    2005-01-01

    The effects of liquid viscosities, solid circulating rates, liquid and gas velocities and phase holdups on the axial dispersion coefficient, Dax, were investigated in a gas-liquid-solid circulating fluidized bed (GLSCFB).Liquid viscosity promotes the axial liquid backmixing when solid particles and gas bubbles are present. Increases in gas velocities and solid circulating rates lead to higher Dax. The effects of liquid velocity on Dax are associated with liquid viscosity. Compared with conventional expanded beds, the GLSCFBs hold less axial liquid dispersion,approaching ideal plug-flow reactors.

  9. Packed fluidized bed blanket for fusion reactor

    Science.gov (United States)

    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.

  10. Heat and Mass Transfer Enforcement of Vibrating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    ChuZhide; YangJunhong; 等

    1994-01-01

    This paper briefly introduces the development of vibrating fluidized bed at home and abroad,elaborates the vibration properties of vibrating fluidized bed.the fluidizing velocity and pressure drop of the bed layer,it also deduces the non-steady state drying dynamic equations of vibrating fluidized bed,analyzes main factors which influence the drying rate and inquires into drying rules of fixed bed and vibrating fluidized bed.

  11. Fluidization Behavior of Ultrafine Powders in an Internal Circulating Fluidized-Bed%超细粉在内循环流化床中的流态化特性

    Institute of Scientific and Technical Information of China (English)

    张国杰; 皮立强; 杨兴灿; 周勇

    2015-01-01

    在内径120 mm的半圆柱形内循环流化床中,以平均粒径387 nm的TiO2为原料,考察了单独通入流化气、射流气和同时通入流化气和射流气三种流化方式下超细粉的流化特性以及射流气速对超细粉聚团尺寸的影响。结果表明:同时通入流化气和射流气时,流化气能促进粉体循环,消除环隙死区;高速射流能有效破碎聚团,显著减小聚团尺寸,从而使超细粉在环隙区与导流管之间形成稳定循环,小聚团在环隙区实现平稳流态化。随着射流气速的增大,聚团尺寸减小,粒度分布变窄,在射流气速分别为60,90,120,150 m/s的条件下,聚团平均直径分别为194,158,147,135μm。%The fluidization characteristics of ultrafine powder TiO2 with an average diameter of 387 nm were investigated in a semi-cylindrical internal circulating fluidized-bed of 120 mm in diameter under three kinds of fluidization condition, introducing fluidizing gas individually, jet gas individually or both gases at the same time. The results indicated that fluidizing gas can promote the circulation of powder and eliminate dead zone in annulus; high-speed jet can effectively break the agglomerates and significantly reduce their size as the fluidizing gas and jet gas were introduced at the same time, so that the stable circulation of ultrafine powder between annulus and draft tube can be achieved and the small agglomerates can be fluidized steadily in annulus. Furthermore, the influence of jet gas velocity on the size of agglomerates was tested in this experiment as well. It was found that the size of the agglomerates becomes smaller and the size distribution becomes narrower with the increased jet gas velocity. The average diameters of the agglomerates were 194, 158, 147, and 135μm under the condition of the jet gas velocity were 60, 90, 120, and 150 m/s, respectively.

  12. Developments in fluidized bed conversion of solid fuels

    Directory of Open Access Journals (Sweden)

    Leckner Bo

    2016-01-01

    Full Text Available A summary is given on the development of fluidized bed conversion (combustion and gasification of solid fuels. First, gasification is mentioned, following the line of development from the Winkler gasifier to recent designs. The combustors were initially bubbling beds, which were found unsuitable for combustion of coal because of various drawbacks, but they proved more useful for biomass where these drawbacks were absent. Instead, circulating fluidized bed boilers became the most important coal converters, whose design now is quite mature, and presently the increments in size and efficiency are the most important development tasks. The new modifications of these conversion devices are related to CO2 capture. Proposed methods with this purpose, involving fluidized bed, are single-reactor systems like oxy-fuel combustion, and dual-reactor systems, including also indirect biomass gasifiers.

  13. Torrefaction of sawdust in a fluidized bed reactor.

    Science.gov (United States)

    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.

  14. Internal Combustion Engines as Fluidized Bed Reactors

    Science.gov (United States)

    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.

  15. Numerical Studies of the Gas-Solid Hydrodynamics at High Temperature in the Riser of a Bench-Scale Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Maximilian J. Hodapp

    2012-01-01

    Full Text Available The hydrodynamics of circulating fluidized beds (CFBs is a complex phenomenon that can drastically vary depending on operational setup and geometrical configuration. A research of the literature shows that studies for the prediction of key variables in CFB systems operating at high temperature still need to be implemented aiming at applications in energy conversion, such as combustion, gasification, or fast pyrolysis of solid fuels. In this work the computational fluid dynamics (CFD technique was used for modeling and simulation of the hydrodynamics of a preheating gas-solid flow in a cylindrical bed section. For the CFD simulations, the two-fluid approach was used to represent the gas-solid flow with the k-epsilon turbulence model being applied for the gas phase and the kinetic theory of granular flow (KTGF for the properties of the dispersed phase. The information obtained from a semiempirical model was used to implement the initial condition of the simulation. The CFD results were in accordance with experimental data obtained from a bench-scale CFB system and from predictions of the semiempirical model. The initial condition applied in this work was shown to be a viable alternative to a more common constant solid mass flux boundary condition.

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

    Science.gov (United States)

    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.

  17. Fluidized bed combustion: mixing and pollutant limitation

    Energy Technology Data Exchange (ETDEWEB)

    Leckner, B. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Energy Conversion

    1997-10-01

    Fluidized bed combustion (FBC) has been applied commercially during a few decades, and sufficient knowledge is gained to design boilers with sizes of up to several hundreds of megawatt thermal power (MW{sub th}). The knowledge of what goes on inside a large combustion chamber is still limited, however, and this impedes further optimization and efficient solution of problems that might occur. Despite this lack of knowledge the present survey deals with combustion chamber processes and discusses mixing and distribution of fuel and air in the combustion chamber and its importance for sulphur capture and reduction of emissions of nitrogen oxides. It is desirable to present the material in a general way and to cover the entire field of FBC. However, the scarce openly published information deals mostly with coal combustion in atmospheric circulating fluidized bed (CFB) combustors, and therefore this application will receive most attention, but reference is also made to pressurized combustion and to other fuels than coal. In this context the important work made in the LIEKKI project on the analysis of different fuels and on the influence of pressure should be especially pointed out. (orig.)

  18. Experimental Study on Gas-Solid Mass Transfer in Circulating Fluidized Beds%循环流化床气固传质实验研究

    Institute of Scientific and Technical Information of China (English)

    王琳娜; 张苓; 靳东杰; 李静海

    2002-01-01

    This study is devoted to gas-solid mass transfer behavior in heterogeneous two-phase flow. Experiments were carried out in a cold circulating fluidized bed of 3.0 m in height and 72 mm in diameter with naphthalene particles. Axial and radial distributions of sublimated naphthalene concentration in air were measured with an online concentration monitoring system HP GC-MS. Mass transfer coefficients were obtained under various operating conditions, showing that heterogeneous flow structure strongly influences the axial and radial profiles of mass transfer coefficients. In the bottom dense region, mass transfer rate is high due to intensive dynamic behavior and higher relative slip velocity between gas and clusters. In the middle transition region and the upper dilute region, as a result of low mass transfer driving force and the influence of flow structure, mass transfer rate distribution becomes non-uniform. In conclusion, among the operating parameters influencing mass transfer coefficients, the superficial gas velocity is the most important factor and the solid circulation rate should be also taken into account.

  19. Experimental study of the mechanisms of CO{sub 2} capture by calcium cycle under circulating fluidized bed conditions; Etude experimentale des mecanismes de capture du CO{sub 2} par cycle calcium en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Hoteit, A

    2006-06-15

    The work undertaken in this Thesis in partnership with department R and D of ALSTOM Power Boilers, CEMEX and the ADEME, relates to the experimental study of various phenomena associated to CO{sub 2} capture under circulating fluidized bed conditions. The size of particles, temperature and the CO{sub 2} concentration have an influence on the limestone calcination reaction. The reaction of carbonation of lime is not total. During successive cycles of calcination/carbonation, the rate of carbonation obtained with hydrated lime is increasingly higher than that obtained with the lime. Under continuously reducing conditions, the decomposition of sulphates present in the bed ashes is not total. This decomposition is total under reduction/oxidation cycles. A modeling of calcination allowed to determine the intrinsic kinetic constants of calcination and carbonation. (author)

  20. Countermeasures against Fouling in Circulating Fluidized Bed Boiler%循环流化床锅炉抵御沾污的对策

    Institute of Scientific and Technical Information of China (English)

    鲁佳易; 巩李明; 聂立; 王鹏; 苏虎; 胡修奎

    2016-01-01

    对循环流化床( Circulating Fluidized Bed, CFB)锅炉燃用典型高钠煤及解决方案进行了综述。首先对比了沾污与结渣的特点与区别,明确目前尚无成熟可靠的方法来解决沾污问题。接着从沾污生成机理着手,分析了沾污的生成过程,阐明沾污通常还伴随着腐蚀。然后根据CFB锅炉的特点,论述其低燃烧温度及气固两相流动在抵御沾污方面的优势,并根据试验结果及现场实际锅炉的运行情况阐述了CFB锅炉的沾污特性。最后,根据CFB锅炉的沾污特点,总结了CFB锅炉燃高钠煤时防止沾污的措施。%This paper presents a review of solutions to and countermeasures against typical fouling due to high sodium content in coal combusted in circulating fluidized bed ( CFB) boilers, The mechanism of fouling and that of slagging are compared concluding that there are no effective and available methods to solve the fouling issues till now. The paper further provides details of the fouling mechanism and its formation process, indicating that the fouling is usually followed by corrosion. Advantages of CFB boilers in anti-fouling due to the two-phase flow characteristic and combustion temperature are given, and the fouling in a CFB boiler along with an experimental study and on a test rig is discussed. Finally, on the basis of the fouling characteristics in CFB boilers, the anti-fouling solutions and methods are presented and relative active methods such as boiler with flue gas recycling system are submitted.

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

    Energy Technology Data Exchange (ETDEWEB)

    Marashdeh, Qussai [Tech4imaging LLC, Columbus, OH (United States)

    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

  2. Numerical Simulation of Physical and Chemical Processes in Fluidized Bed

    Science.gov (United States)

    Baturin, D. A.; Gil, A. V.

    2015-10-01

    The paper presents a numerical simulation of the furnace with a circulating fluidized bed. Numerical study carried out for the bottom of the combustion chamber with the varying heights of volume filling. The results contours of particulate matter concentration and of velocities, as well as a graphical representation of changes in the concentration of particles on the bed height are shown. Simulation performed in Eulerian - Eulerian representation on a 2D model.

  3. Phase-Plane Invariant Analysis of Pressure Fluctuations in Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaoliang; HE Rong; Toshiyuki Suda; Junichi Sato

    2007-01-01

    Partial agglomeration is a major problem in fluidized beds. A chaotic analytical method based on the phase-plane invariant of the pressure fluctuations in the fluidized beds has been used to warn of agglomeration at an early stage. Cold tests (no combustion) and hot tests (combustion) in fluidized beds show that the phase-plane invariant of the pressure fluctuations can distinguish the dynamic behavior of fluidized beds with different flow rates in cold tests. With combustion, when the flow rate was kept constant, agglomeration was detected very early by looking at the phase-plane invariant. The phase-plane invariant can be used to distinguish changes in fluidized beds due to changes in the flow rate, agglomeration, or various other factors. Therefore, this reliable agglomeration early warning system can be used for better control of circulating fluidized beds.

  4. Combustion and adjustmen of North pot GB-75/5.29-M type circulating fluidized bed boiler%北锅GB-75/5.29-M型循环流化床锅炉的燃烧和调整

    Institute of Scientific and Technical Information of China (English)

    赵解放

    2012-01-01

      In the article, design parameters、the combustion adjustment and so on, on circulating fluidized bed boiler were introduced, the corresponding measures were taken, the performance of the boiler were effectively improved.%  介绍循环流化床锅炉的设计参数、燃烧调整等,采取的相应措施,有效改进了锅炉的运行性能。

  5. Hydrodynamics of gas-solids downflow fluidized bed (downer) reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.

    1999-07-01

    This study presents a semi-empirical model for the hydrodynamic flow structure in a circulating fluidized bed downer reactor. Circulating fluidized bed, or riser reactors are used in the petroleum industry for many applications including catalytic cracking, polyethylene production, calcination operations and combustion of a variety of fuels. The work in this thesis involved the development of a circulating fluidized bed riser and downer system that enables hydrodynamic studies to be carried out. The system was designed to incorporate both a riser and a downer in the same circulating operation, making it possible to conduct experimental studies on the riser and the downer separately or simultaneously. The hydrodynamics of the gas-solids downflow fluidized bed reactor were studied in a 9.3 m tall and 0.1 m i.d. circulating fluidized bed downer reactor using fluidized cracking catalyst (FCC) particles. In order to characterize the gas-solids flow structures, the following three parameters were measured: the radial distributions of the local solids holdups, the local particle velocities, and the pressure gradients along the downer column. The hydrodynamics in the co-current downflow reactor was also studied under a wide range of operating conditions. The gas-solids flow structure under zero superficial gas velocity conditions was characterized by measuring the radial distribution of the local solids holdups and particle velocities along the downer column with the superficial gas velocity set to zero. The results indicate that two basic flow regimes exist in the FCC downer system depending on the superficial gas velocity. The downer reactor was shown to have a more uniform radial flow structure compared to the riser. It also has a more uniform radial distribution of solids holdup and particle velocity as well as solids flux in both the development and fully developed zones. The highly uniform radial flow structure provides a nearly ideal plug flow condition in the

  6. Properties of circulating fluidized bed combustion ashes road base materials%固硫灰路面基层材料的性能

    Institute of Scientific and Technical Information of China (English)

    尹元坤; 卢忠远; 李军; 牛云辉

    2012-01-01

    Circulating fluidized bed combustion ashes (FBCF) were used as road base materials. The properties of original and pretreated FBCF road base materials were studied. And the influence of heavy metal of FBCF on the soil was also researched through leaching experiments. Results show that high volume stability, low inflation rates and the better road performance were obtained when pretreated FBCF was used. In addition, FBCF road base materials have lower heavy metal leaching rate, which in line with environmental protection require- ments.%以固硫灰作为路面基层材料,研究了固硫灰原灰和经预处理固硫灰路面基层材料的最佳含水量、最大干密度、体积安定性、膨胀率和强度等性能。同时,通过重金属浸出实验评估了固硫灰对土壤环境的影响。结果表明,经预处理固硫灰路面基层材料体积安定性好,膨胀率低,性能良好;此外,固硫灰重金属浸出率低,符合环保要求。

  7. Evaluation of PCDD/Fs and metals emission from a circulating fluidized bed incinerator co-combusting sewage sludge with coal.

    Science.gov (United States)

    Zhang, Gang; Hai, Jing; Cheng, Jiang; Cai, Zhiqi; Ren, Mingzhong; Zhang, Sukun; Zhang, Jieru

    2013-01-01

    The emission characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and heavy metals were evaluated during co-combustion of sewage sludge with coal from a circulating fluidized bed incinerator. The stack gas, slag and fly ash samples were sampled and analyzed. The gas-cleaning system consisted of electrostatic precipitators and a semi-dry scrubber. Results showed that the stack gas and fly ash exhibited mean dioxin levels of 9.4 pg I-TEQ/Nm3 and 11.65 pg I-TEQ/g, respectively, and showed great similarities in congener profiles. By contrast, the slag presented a mean dioxin level of 0.15 pg I-TEQ/g and a remarkable difference in congener profiles compared with those of the stack gas and fly ash. Co-combusting sewage sludge with coal was able to reduce PCDD/Fs emissions significantly in comparison with sewage sludge mono-combustion. The leaching levels of Hg, Pb, Cd, Ni, Cr, Cu, and As in the fly ash and slag were much lower than the limits of the environmental protection standard in China. These suggest that the co-combustion of sewage sludge and coal is an advisable treatment method from an environmental perspective.

  8. Multiobjective optimization of the operation of a liquid-solid circulating fluidized bed ion-exchange system for continuous protein recovery.

    Science.gov (United States)

    Mazumder, Jahirul; Zhu, Jingxu; Bassi, Amarjeet S; Ray, Ajay K

    2009-08-01

    Like most real-life processes, the operation of liquid-solid circulating fluidized bed (LSCFB) system for continuous protein recovery is associated with several objectives such as maximization of production rate and recovery of protein, and minimization of amount solid ion-exchange resin requirement, all of which need to be optimized simultaneously. In this article, multiobjective optimization of a LSCFB system for continuous protein recovery was carried out using an experimentally validated mathematical model to find the scope for further improvements in its operation. Elitist non-dominated sorting genetic algorithm with its jumping gene adaptation was used to solve a number of bi- and tri-objective function optimization problems. The optimization resulted in Pareto-optimal solution, which provides a broad range of non-dominated solutions due to conflicting behavior of the operating parameters on the system performance indicators. Significant improvements were achieved, for example, the production rate at optimal operation increased by 33%, using 11% less solid compared to reported experimental results for the same recovery level. The effects of operating variables on the optimal solutions are discussed in detail. The multiobjective optimization study reported here can be easily extended for the improvement of LSCFB system for other applications.

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

    Science.gov (United States)

    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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

    Geopolymers are three-dimensional aluminosilicates formed in a short time at low temperature by geopolymerization. In this pa-per, 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 mi-croscopy (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 geo-polymers appear the relatively optimized pore structure and distribution, which are beneficial to the structure stability. Moreover, a combina-tion 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.

  11. 75 t/h循环流化床锅炉改造%The Reform of A 75t/h Circulating Fluidized Bed Boiler

    Institute of Scientific and Technical Information of China (English)

    阴志青

    2013-01-01

    In the view of the abrasion of wind chamber and small bell cap, material returning device which is easy to bend and deform under the condition of high temperature, poor use reliability, the serious ash deposition, the reform of a 75t/h circulating fluidized bed boiler can bet⁃ter paly the role of energy-saving and power-saving, improve boiler efficiency, reduce boiler abrasion, improve the economy and stability of boiler.%  鉴于某75 t循环流化床锅炉的风室风帽磨损严重及返料装置高温状态下易发生弯曲变形、使用可靠性较差、尾部积灰严重等问题进行改造;更好地发挥循环流化床锅炉节能节电,提高锅炉的效率,减少锅炉的磨损,提高锅炉运行经济性与稳定性。

  12. Wear prediction in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, E.J. [USDOE Morgantown Energy Technology Center, WV (United States); Rogers, W.A. [EG and G Washington Analytical Services Center, Inc., Morgantown, WV (United States)

    1993-06-01

    A procedure to model the wear of surfaces exposed to a fluidized bed is formulated. A stochastic methodology adapting the kinetic theory of gases to granular flows is used to develop an impact wear model. This uses a single-particle wear model to account for impact wear from all possible-particle collisions. An adaptation of a single-particle abrasion model to describe the effects of many abrading particles is used to account for abrasive wear. Parameters describing granular flow within the fluidized bed, necessary for evaluation of the wear expressions, are determined by numerical solution of the fluidized bed hydrodynamic equations. Additional parameters, describing the contact between fluidized particles and the wearing surface, are determined by optimization based on wear measurements. The modeling procedure was used to analyze several bubbling and turbulent fluidized bed experiments with single-tube and tube bundle configurations. Quantitative agreement between the measured and predicted wear rates was found, with some exceptions for local wear predictions. This work demonstrates a methodology for wear predictions in fluidized beds.

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

    Science.gov (United States)

    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.

  14. Transfer Function Modeling Method of Bed Temperature Based on Swarm Intelligence Algorithm in Circulating Fluidized Bed Boiler%循环流化床锅炉床温的传递函数智能建模方法

    Institute of Scientific and Technical Information of China (English)

    王利杰; 孙明; 程希; 殷立国; 孙剑

    2013-01-01

    通过研究循环流化床锅炉燃烧系统的机理和非参数建模方法,基于对循环流化态燃烧机理的认知,给出模型辨识的数据选择标准;挖掘机组运行的历史数据,提出了利用群体智能寻优算法进行燃料量与床温之间传递函数的参数辨识方法,并给出了快速仿真的公式以及一类单输入单输出系统的辨识结果和验证方法。所建立的传递函数模型完全能够表征具体某台循环流化床锅炉热工特性,为后续的控制逻辑和控制器的优化提供了数学依据。%This paper summarized two methods which include mechanism and non-parametric modeling in the cir-culating fluidized bed ( CFB) boiler's combustion system. Based on the understanding of combustion principle of circulating fluidized state, the criterion of data selection was given. By mining the historical datas of unit operation, a method of identifying undetermined parameters of the transfer function between fuel and bed temperature using the swarm intelligence optimizing algorithms was presented. Then, the rapid simulation formulas of thermal process and identification result and validation method of a class of single-input single-output system were given. Transfer func-tion which was established by this method can entirely represent the thermal characteristics of CFB boiler and pro-vide a mathematical basis for subsequent control logic or parameter's optimization of controller.

  15. METHOD FOR SENSING DEGREE OF FLUIDIZATION IN FLUIDIZED BED

    Science.gov (United States)

    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)

  16. Understanding and predicting bed humidity in fluidized bed granulation.

    Science.gov (United States)

    Hu, Xinhui; Cunningham, John; Winstead, Denita

    2008-04-01

    Bed humidity is a critical parameter that needs to be controlled in a fluidized bed granulation to ensure reliability. To predict and control the bed humidity during the fluidized bed granulation process, a simple model based on the mass conservation of moisture was developed. The moisture mass balance model quantitatively simulates the effects of spray rate, binder solution concentration, airflow rate, inlet air temperature, and dew point on the bed humidity. The model was validated by a series of granulations performed in different scale granulators including Glatt GPCG-1, GPCG-15, and GPCG-60. Good agreement was observed between the theoretical prediction and the measured loss on drying (LOD). The model developed in the current work enables us to choose the appropriate parameters for the fluidized bed granulation and can be used as a valuable tool in process scaling-up.

  17. Particle pressures in fluidized beds. Final report

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Particle Pressures in Fluidized Beds. Final report

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Application of active disturbance rejection control in bed temperature control of circulating fluidized bed boiler%自抗扰控制在循环流化床锅炉床温控制中的应用

    Institute of Scientific and Technical Information of China (English)

    马晓勇; 吴宏艳

    2011-01-01

    床温是循环流化床锅炉燃烧控制系统中的一个重要指标.它的稳定与否直接影响着锅炉的燃烧效率和污染物排放速率.在燃烧过程中,它具有时变性、大惯性和大滞后的特点.针对这一问题将自抗扰控制算法应用于循环流化床锅炉床温控制,并将仿真结果与PID控制方法的仿真结果进行了比较.研究表明:ADRC在超调量、调节时间上均优于常规PID方法,在各种工况以及增加外扰情况下,该自抗扰控制方案具有良好的鲁棒性和抗干扰能力,解决了该系统时变、大延迟的控制难点.%The bed temperature is an important parameter for a CFB (circulating fluidized bed) boiler. Wheather it is stable or not directly influences the boiler overall efficiency and the rate of pollutants emission. At the same time, the bed temperature control system is an uncertain system with large inertia and lag. Directing against the problems, the active disturbance rejection control (ADRC) was used to bed temperature control in a circulating fluidized bed boiler ( CFBB). The simulation results were compared with those obtained by using PID control method. It was found that the overshooting and regulation time duration of the ADRC are superior to those of the convention PID method under various operating conditions and with an increase of disturbance from the outside, the ADRC presents a good robustness and disturbance-resistant capability, thus solved the difficulties in controlling the time variation and long time delay of the system.

  20. Pulsed atmospheric fluidized bed combustion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Lateral Solids Mixing in the Dense Zone of a Circulating Fluidized Bed%循环流化床密相区内颗粒的横向扩散的研究

    Institute of Scientific and Technical Information of China (English)

    杨海瑞; 吕俊复; 刘青; 岳光溪

    2002-01-01

    Lateral solid mixing was investigated experimentally in the dense zone of a 900mm×100mm×5.2m rectangular circulating fluidized bed riser. Using heated tracer injection, the lateral solid dispersion was determined by measuring the temperature response at different lateral positions. Furthermore, a one-dimensional dispersion model, which describes the solid mixing in the dense zone, is presented. The experimental results were used to determine the lateral particle dispersion coefficient under various operating conditions. A correlation of dispersion coefficient with bed height, gas velocity, and particle size is also proposed.

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

    Science.gov (United States)

    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.

  3. Fluidized-bed reactors processes and operating conditions

    CERN Document Server

    Yates, John G

    2016-01-01

    The fluidized-bed reactor is the centerpiece of industrial fluidization processes. This book focuses on the design and operation of fluidized beds in many different industrial processes, emphasizing the rationale for choosing fluidized beds for each particular process. The book starts with a brief history of fluidization from its inception in the 1940’s. The authors present both the fluid dynamics of gas-solid fluidized beds and the extensive experimental studies of operating systems and they set them in the context of operating processes that use fluid-bed reactors. Chemical engineering students and postdocs as well as practicing engineers will find great interest in this book.

  4. Fluidization Characteristics of a Prototype Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    F. ABERUAGBA

    2005-01-01

    Full Text Available The fluidization characteristics of a prototype-fluidized bed laboratory reactor were understudied in order to investigate the suitable conditions at which the dehydrogenation reaction of butane could be carried out. To achieve this, a reactor with an effective volume of 1100ml was fabricated and coupled with temperature and pressure accessories.Zeolites were obtained from the market and clay obtained from different sources and pre-treated was used as catalyst. Airflow at high velocity between 3000-7000ml/hr was used as the fluidising medium to obtain the bed characteristics while butane gas was used to obtain the dehydrogenation kinetics.The temperature of the reactor system was varied between 353K and 413K while maintaining constant pressure of 1.5 105 N/m2 through a manifold gauge and a constant catalyst weight. Various methods such as pressure fluctuations, visual observations, and bed expansion were used to determine the transition velocity at which fluidization begins. It was observed that this depends on factors such as mean particle size, particle size distribution, and column diameter.The minimum fluidizing velocity obtained for zeolite was 0.0133m/s and 0.0102m/s for treated clay materials both for a particle size of 250μm. The conversion of butane over the catalysts showed an increase in both cases with a maximum at 0.9813 at 413K. This decreases as the reaction progresses.

  5. Circulating fluidized bed combustion fly ash based mineraladmixturesused in concrete%固硫灰作矿物掺和料制备混凝土研究

    Institute of Scientific and Technical Information of China (English)

    莫兆庭

    2015-01-01

    Circulating fluidized bed combustion (CFBC) fly ash was the waste that discharged by circulating fluidized bed boiler, which contained certain amount of chainotte minerals. The chemical compositions and physical properties of CFBC fly ashwere distinct with ordinary fly ash, which were suited to be used in construction materials.However, CFBC fly ash has its own special nature, such as self-hardening, pozzolanic activity and expansion characteristics, which restrict the utilization in building materials. In this paper,the physical and chemical properties of CFBC fly ash were characterized by SEM, particle size analysis,etc. And the activity index of CFBCand composite system contained CFBC fly ash, ordinary fly ash and slag were measured. The utilization of CFBC fly ash in concrete has also been discussed. Results showed that the activity index of CFBC fly ash increased with decreasing of the particle size of CFBC fly ash. The activity index would be decreased when ordinary fly ash and slag were mixed. The CFBC fly ash could be used to prepare concrete. And the properties of the prepared concrete would be improved with addition of CFBC fly ash in certain content range.%固硫灰是循环流化床烧煤技术所产生的废弃物,含有部分烧粘土质矿物,与普通粉煤灰相比其化学组成和性质有一定差异,经过一定加工和配料可以做建筑材料的原材料。但因为固硫灰有其自身特殊性质,如自硬性、火山灰活性和膨胀性等特点,因此在建筑材料领域应用受到一定限制。本文利用SEM微观分析、粒径分析等手段研究了固硫灰的物化特性,同时对固硫灰、粉煤灰、矿粉的活性指数进行分析,并将固硫灰作为矿物掺合料制备混凝土。实验结果表明:固硫灰活性随着粒径减小而增加,与粉煤灰和矿粉复掺会降低体系的活性指数;可以利用固硫灰做矿物掺合料制备混凝土,且其掺量在一定范围内对改善

  6. Study on high belite cement clinker calcination with ashes from circulating fluidized bed combustion%固硫灰制备高贝利特水泥

    Institute of Scientific and Technical Information of China (English)

    吕淑珍; 陈雪梅; 卢忠远; 彭艳华

    2011-01-01

    In order to explore new utilizing approach of ashes from circulating fluidized bed combustion(CFBC ashes for short), high belite cement is prepared by using CFBC ashes to substitute partial raw materials. Calcining temperature and mineral composition of clinker are analyzed by thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD) respectively, and the physical mechanical properties of clinker are tested. The results show that the main minerals of high belite cement clinker are C2S,C4A3S,G2AF and CaSO4;compression strength of 3 days is more than 30 Mpa.and that of 28 days is more than 80 Mpa while incorporation of proper amount of gypsum.%为了探索固硫灰新的利用途径,利用固硫灰替代部分原料制备高贝利特水泥,采用TG-DTA综合热分析法、XRD射线衍射等方法分别确定了生料的煅烧温度和熟料的矿物组成,并对水泥的物理力学性能进行了检测.研究表明,制备的高贝利特水泥主要矿物组成是C2S、C4A3(S)、C2AF和CaSO4;掺入适量的石膏后,其3d抗压强度达到30 MPa以上,28 d抗压强度达到80 MPa以上.

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

    Science.gov (United States)

    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

  8. Emissions of SO2, NO and N2O in a circulating fluidized bed combustor during co-firing coal and biomass.

    Science.gov (United States)

    Xie, Jian-jun; Yang, Xue-min; Zhang, Lei; Ding, Tong-li; Song, Wen-li; Lin, Wei-gang

    2007-01-01

    This paper presents the experimental investigations of the emissions of SO2, NO and N20 in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N20 were proposed.

  9. Emissions of SO2,NO and N2O in a circulating fluidized bed combustor during co-firing coal and biomass

    Institute of Scientific and Technical Information of China (English)

    XIE Jian-jun; YANG Xue-min; ZHANG Lei; DING Tong-li; SONG Wen-li; LIN Wei-gang

    2007-01-01

    This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O are studied. The results show that an increase in the biomass shares results in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with the increasing biomass share slightly however, non-linear increase relationship between SO2 emission and fuel sulfur content is observed. Air staging decreases the NO emission significantly without raising the SO2 level. Though change the fuel feeding position from riser to downer results in a decrease in the NO emission level, no obvious change is observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission can significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions are discussed and the ways of simultaneous reduction of SO2, NO and N2O are proposed.

  10. Technical and economical optimization of wood gasification in a circulating fluidized bed. Final report; Technische und wirtschaftliche Optimierung der Vergasung von Holz in der zirkulierenden Wirbelschicht. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Ising, M.; Unger, C.; Heunemann, F.; Dinkelbach, L.

    2002-12-01

    The project's objective was the optimization of a novel process for high efficient combined heat and power production from solid biomass. The processed air blown wood gasification in a pilot scale circulating fluidized bed was added by a catalytic tar reformer which would yield a tar-free gas quality suitable for IC-engine operation. Major efforts were taken for technical improvement of the tar reformer, especially concerning temperature control and cleaning devices which is important for keeping constantly a high activity. Pure natural timber did not yield chemical deactivation at the catalyst whereas the gasification of waste wood yielded decreasing activity which could be partly reversed by special measures taken. Further optimization of the process considered a better automation and improvement of the engine's flue gas emissions. Also a detailed economic consideration and evaluation of the entire process has been carried out. As a result the novel process should have economic advantages compared with conventional technology. (orig.) [German] Gegenstand des Vorhabens war die Weiterentwicklung eines Verfahrens zur effizienteren Strom- und Waermegewinnung aus festen Biobrennstoffen. Durch luftgeblasene Vergasung von Holz im Pilotmassstab in einer zirkulierenden Wirbelschicht und anschliessender katalytischer Teerspaltung konnte ein niederkalorisches Brenngas erzeugt werden, welches zum Betrieb eines Motoren-Blockheizkraftwerks geeignet war. Im Rahmen der Verfahrensoptimierung wurde der katalytische Teer-Reformer, insbesondere in Bezug auf Temperaturfuehrung und die zum Aktivitaetserhalt wichtige Abreinigungsvorrichtung, verbessert. Bei der Vergasung von Naturholz wurde keine chemische Desaktivierung festgestellt. Beim Altholzeinsatz wurde ein ueberwiegend reversibler Aktivitaetsverlust verzeichnet und begruendet. Geeignete Gegenmassnahmen wurden untersucht und beschrieben. Weitere Optimierungen betrafen die Anlagensteuerungstechnik im Hinblick auf die

  11. Gasification of secondary fuels in a circulating fluidized bed for energetic use in cement production; Vergasung von Sekundaerbrennstoffen in der zirkulierenden Wirbelschicht zur energetischen Nutzung fuer die Zementherstellung

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, J.; Gafron, B. [Lurgi Umwelt GmbH, Frankfurt am Main (Germany); Scur, P.; Wirthwein, R. [Ruedersdorfer Zement GmbH (Germany)

    1998-09-01

    Ruedersforf cement factory was commissioned a century ago as one of the first in Germany. After the plant was taken over by Readymix AG, a comprehensive sanitation concept was carried through. The plant has a production capacity of 8000 t/d of cement clinkers which are produced in a new kiln with a capacity of 6000 t/d and two modernized kilns each with a capacity of 1000 t/d. Reduction of energy consumption was the main goal of modernisation, with fuel gas generation in a circulating fluidized bed as a key element. The unit provides 40 % of the energy consumed by the clinker production process and is also used for selective ash production up to 25 t/h. The ash is used as a raw material for cement production. (orig./SR) [Deutsch] Bereits vor 100 Jahren wurde eine der ersten Zementfabriken in Deutschland am Standort Ruedersdorf in Betrieb genommen. Zum Erhalt der Wettbewerbsfaehigkeit wurde nach der Uebernahme des Werkes Ruedersdorf durch die Readymix AG ein umfangreiches Sanierungskonzept in die Wege geleitet. Bei einer Produktionskapazitaet von ca. 8 000 t Klinker pro Tag werden eine neue Ofenanlage mit einer Kapazitaet von 6 000 t/Tag sowie 2 sanierte kleine Anlagen zu je 1000 t/Tag betrieben. In der neuen Ofenanlage werden alle Moeglichkeiten genutzt, den Energiebedarf fuer die Klinkerproduktion zu senken. Eine wesentliche neue innovative Komponente ist dabei eine Brenngaserzeugung in einer Zirkulierenden Wirbelschicht, ueber die im folgenden berichtet werden soll. Die Anlage kann bis zu 40% des Energiebedarfes des Zementprozesses liefern. Weiterhin wird mit der ZWS eine gezielte Ascheproduktion, bis zu 25 t/h, betrieben. Diese Aschen sind Teil der Rohstoffrezeptur an der Rohmuehle. (orig./SR)

  12. Photocatalytic oxidation of Rhodamine B in a three-phase internal circulating fluidized bed with TiO2/SiO2 as photocatalyst

    Institute of Scientific and Technical Information of China (English)

    YOU Hong; SUN Li-xin; LUO Wei-nan; LIU Ting

    2010-01-01

    A novel photoreactor of three-phase internal circulating fluidized bed was applied to the degradation of Rhodamine B with TiO/SiO2 catalyst and TiO2 powder,respectively.The experimental results showed that the photocatalytic activity of TiO2/SiO2 catalyst was much higher than that of TiO2 powder under the same condition,and the half life of Rhodamine B using TiO2/SiO2 was 9.5 min,much lower than 63 min when using TiO2 powder.Moreover,TiO2/SiO2 had a good adsorption capacity of Rhodamine B,which played an important role on degradation.In addition,it was found that the degradation kinetics of Rodamine B with TiO2/SiO2 catalyst did not follow the first order reaction.The degradation kinetics model in terms of the adsorption process of catalyst and the analytic solution of reactant degradation rate in liquid phase could be deduced,which consisted of two parts.The first part was due to the adsorption,while the second part was due to the photocatalysis.In the beginning of the reaction,the adsorption process was dominant.However,when the adsorption achieved a balance,the degradation of Rhodamine B in liquid phase and solid phase was mainly caused by photocatalysis and the degradation kinetics model conformed to the first order reaction.

  13. The heat transfer mechanisms in fluidized beds; Laemmoensiirtomekanismit leijukerroksessa

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Blomster, A.M.; Kojola, H. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Energy Technology and Environmental Protection

    1997-10-01

    The goal of the research project is to improve the accuracy of the heat transfer correlation in circulating fluidized beds and to define how the heat transfer is distributed in radiation and convection in the different parts of the fluidized bed. This will be carried out by studying the behaviour and the heat transfer of the fluidized bed in the boundary layer near the wall. During the project the concentration and the velocity of the sand particles are measured. The particle concentration and the particle velocity are measured by an image analysis system. A video camera and a Super VHS recorder are used to capture live images from the bed. The images are digitized and stored on a PC. The measured particle concentration was at highest slightly over 20 % on the straight wall. As expected, the velocity of the fluidizing gas had the most important role on the particle concentration. The experimental studies of the particle velocity were started last autumn 1996. The velocities of the particles were measured by using a multiple exposure technique. Afterwards the images captured were analyzed by performing a Fourier transform analysis. So far the results have been encouraging and the analyzing work will be ended this spring. (orig.)

  14. Artificial neural network models for biomass gasification in fluidized bed gasifiers

    DEFF Research Database (Denmark)

    Puig Arnavat, Maria; Hernández, J. Alfredo; Bruno, Joan Carles

    2013-01-01

    bed gasifier can be successfully predicted by applying neural networks. ANNs models use in the input layer the biomass composition and few operating parameters, two neurons in the hidden layer and the backpropagation algorithm. The results obtained by these ANNs show high agreement with published......Artificial neural networks (ANNs) have been applied for modeling biomass gasification process in fluidized bed reactors. Two architectures of ANNs models are presented; one for circulating fluidized bed gasifiers (CFB) and the other for bubbling fluidized bed gasifiers (BFB). Both models determine...

  15. Velocity Fluctuations in Gas-Fluidized Beds

    Science.gov (United States)

    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

  16. Investigation of dynamic load changes of a combined cycle power plant with circulating pressurized fluidized bed using a simulation model; Untersuchungen zum dynamischen Lastaenderungsverhalten eines Kombi-Kraftwerks mit zirkulierender Druckwirbelschicht mit Hilfe eines Simulationsmodells

    Energy Technology Data Exchange (ETDEWEB)

    Bockamp, S.; Krumm, W.

    2001-07-01

    Fluidized bed combustion technology offers high efficient power plants with low emissions using coal, biomass or waste as fuel input. Mathematical models support the optimisation and design of power plants. The mathematical fluidized bed system model developed at the Institut fuer Energietechnik, Universitaet Siegen, allows the simulation of steady state or dynamic process operation behaviour. This model is used for detailed examining of the overall combined cycle power plant and the interactions between the single components gas turbine, furnace and water-/steam cycle. The described simulation model presented in this paper is applied for the determination of the transient operation behaviour of a combined cycle power plant based on pressurized circulating fluidized bed combustion. The effects of a step function load change on the temperature profile, the emissions and on process reaction of water/steam cycle and on gas turbine is analysed and discussed in detail at different component outlets. (orig.) [German] Das Kombi-Kraftwerk mit zirkulierender Druckwirbelschichtfeuerung stellt ein effizientes und emissionsarmes Konzept dar. Neben den wirbelschichtinhaerenten Eigenschaften wie geringerer Schadstoffbildung durch niedrige Feuerraumtemperaturen und der integrierten Schadstoffreduktion durch die Zugabe von Zuschlagstoffen verspricht die druckaufgeladenen Variante aufgrund der hohen Querschnittsbelastung eine kompakte Bauart sowie einen fuer die Verstromung von Kohlen hohen Wirkungsgrad. Kohle kann mit diesem Verfahren direkt innerhalb eines Gasturbinenprozesses genutzt werden. Mit Hilfe der mathematischen Modellbildung koennen die dynamischen Auswirkungen auf das Gesamtsystem Kombi-Kraftwerk untersucht werden. (orig.)

  17. Multiscale modeling of gas-fluidized beds

    NARCIS (Netherlands)

    Hoef, van der M.A.; Sint Annaland, van M.; Andrews, A.T.; Sundaresan, S.; Kuipers, J.A.M.

    2006-01-01

    Numerical models of gas-fluidized beds have become an important tool in the design and scale up of gas-solid chemical reactors. However, a single numerical model which includes the solid-solid and solid-fluid interaction in full detail is not feasible for industrial-scale equipment, and for this rea

  18. Agglomeration in fluidized beds: detection and counteraction

    NARCIS (Netherlands)

    Bartels. M.

    2008-01-01

    Fluidized beds comprise a quantity of solid particles that is suspended by an upward flowing gas. They are used for a variety of processes in the chemical industry, such as catalytic reactions, drying, coating and energy conversion. A major problem in industrial practice is the occurrence of unwante

  19. Control of fluidized bed tea drying

    NARCIS (Netherlands)

    Temple, S.J.

    2000-01-01

    Tea is a product made from the leaf of the tea bush by several processes, including drying. The drying stage is the most energy intensive, and has tight performance criteria. This project investigated the options for the control of a fluidized bed tea dryer. The work included establishing some of th

  20. The heat transfer mechanisms in fluidized beds; Laemmoensiirtomekanismit leijukerroksessa

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Blomster, A.M.; Kojola, H. [Helsinki Univ. of Technology, Espoo (Finland)

    1996-12-01

    The goal of the research project is to improve the accuracy of the heat transfer correlation in circulating fluidized beds and to define how the heat transfer is distributed in radiation and convection in the different parts of the fluidized bed. This will be carried out by studying the behaviour and heat transfer of the fluidized bed in the boundary layer near the wall. The total and radiative heat transfer as well as the particle concentration will be measured. Based on the data a correlation will be created. Two different measurement systems are used. The particle concentration is measured by a image-analysis system. A video camera and a Super VHS recorder are used to capture live images from the bed. The images are digitized and stored on a PC. The system has been used in previous research projects at our laboratory. In earlier projects all measurements have been carried out in cold environments. In this project the system will be modified for hot environments. The radiative heat transfer is measured by a radiative heat transfer probe connected to a PC via an A/D converter. The probe consists of a heat flow detector which is isolated from the bed by a sapphire window so that only the radiative part of the heat transfer is detected. The probe will be calibrated in a black body oven so that the effect of the conduction and the sapphire window can be separated. (author)

  1. Research of Nitrous Oxide Emission Characteristics on Lignite Circulating Fluidized Bed%大型褐煤循环流化床锅炉氧化亚氮排放特性

    Institute of Scientific and Technical Information of China (English)

    邱亚林

    2014-01-01

    The research of nitrous oxide emission characteristics on lignite circulating fluidized bed was carried out,the Various pa-rameters effect about the nitrous oxide emissions was studied� Thus the way of reduce nitrous oxide emission concentration was sought.%针对褐煤循环流化床开展氧化亚氮排放特性的研究,掌握不同参数对氧化亚氮排放的影响,从而提出降低氧化亚氮排放浓度的方法。

  2. Hydrodynamique, transfert de chaleur et combustion de gaz naturel en lit fluidisé circulant Hydrodynamics, Heat Transfer and Combustion of Natural Gas in a Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Feugier A.

    2006-11-01

    Full Text Available L'hydrodynamique, les transferts de chaleur et la combustion du gaz naturel ont été étudiés dans un réacteur à lit circulant de 15 cm de diamètre et de 7 m de haut. Ce réacteur peut opérer avec des vitesses de gaz allant jusqu'à 15 m/s, jusqu'à des températures de 880-900°C et avec des débits de solides compris entre 0 et 15t/h. Les charges utilisées sont des sables de granulométrie allant de 95 à 625 microns. Le profil de concentration en solides dans le réacteur est déterminé à partir du profil de pression. Une corrélation reliant la vitesse de glissement des particules aux principaux paramètres opératoires, rend compte de façon très satisfaisante de l'ensemble des résultats expérimentaux. La mise en place d'un échangeur en paroi dans la partie supérieure du réacteur a permis la détermination de coefficients d'échange thermique. Ces derniers sont essentiellement fonction de la, concentration en particules au droit de l'échangeur et de la granulométrie des particules. Des valeurs allant jusqu'à 200 W/m2 K peuvent, être obtenues. Enfin, la combustion du méthane s'avère très sensible à la présence de particules dans le réacteur. Ces particules ont un effet inhibiteur. Hydrodynamics, heat transfer and combustion of natural gas have been investigated in a circulating-bed reactor 15 cm in diameter and 7 m high. This reactor can operate with gas velocities up to 15 m/s, at temperature up to 880-900°C and with solids flow rates of between 0 and 15 t/h. The solids used are sands with a particle size ranging from 95 to 625 microns. The solids concentration profile in the reactor is determined from the pressure profile. A correlation linking the slippage velocity of particles to the principal operating parameters very satisfactorily takes into consideration the overall experimental results. The installation of a wall heat exchanger in the upper part of the reactor enabled the heat exchange coefficients to be

  3. 低固含率气-液-固循环流化床流动特性%Hydrodynamics in gas-liquid-solids circulating fluidized beds with low solids holdups

    Institute of Scientific and Technical Information of China (English)

    刘建华; 刘明言; 胡宗定

    2013-01-01

    Hydrodynamics in gas-liquid-solids circulating fluidized beds with low solids holdups of resin particles was experimentally investigated with a high-speed image measurement and treatment technique of complementary metal oxide semiconductor. Influences of superficial liquid velocity, particle diameter and density, liquid surface tension and viscosity on the phase holdups, average gas bubble diameter, circulating rate of solids particles both in the riser and in the downer and bubble motions were investigated. Experimental data with reasonable physical explanations of the hydrodynamics of gas-liquid-solids circulating fluidized beds were obtained.%应用基于互补金属氧化物半导体(complementary metal oxide semiconductor,CMOS)传感器的高速图像采集和处理技术,实验研究了低固含率条件下,低密度大孔吸附树脂固体颗粒气-液-固三相循环流化床的流体力学行为,分析了操作条件、液相物性、颗粒性质等对床内的固体颗粒循环速率、相含率、气泡运动等特性的影响,得到了具有合理物理解释的实验数据和结果.

  4. Modeling of clusters characteristics in circulating fluidized beds%循环流化床中颗粒聚团特性的模拟

    Institute of Scientific and Technical Information of China (English)

    王帅; 刘国栋; 赵飞翔; 张清红; 陆慧林

    2014-01-01

    Considering the multi-scale structure of the dense phase in the form of clusters and the dilute phase in the form of dispersed particles in the circulating fluidized bed, the relationship between accelerations and local structure parameters in the dense phase and dilute phase was established and the stability condition of the minimum energy dissipation by multi-scale drag force was proposed. Based on the bivariate extreme value theory, a cluster structure dependent (CSD) drag coefficient model was developed. Gas-solids flow behavior and cluster characteristics in risers were simulated using a two-fluid model. The concentrations of particles obtained by the CSD model showed better agreement with experimental results. Cluster diameter increased, reached a maximum and fell down to single particle diameter with increasing solids concentrations. In the simulation, the influence of accelerations of gas and particles could not be ignored because it appeared to be on the same order of magnitude as acceleration of gravity.%考虑到循环流化床中分散颗粒和颗粒聚团同时存在的多尺度结构,确定了密相和稀相加速度与计算网格局部参数之间的关系,建立了多尺度曳力消耗能量最小的稳定性条件,基于双变量极值理论,构建了考虑颗粒团聚效应的多尺度气固相间曳力模型。结合双流体模型,对循环流化床内气固流动特性以及颗粒聚团特性进行了模拟研究。通过与实验值比较,考虑颗粒聚团影响的计算模型可以更好地贴近实验结果,颗粒聚团直径随颗粒浓度增大呈现先增大后减小的分布趋势,气体和颗粒的加速度在模拟中与重力加速度同处一个数量级,求解过程中不能被忽略。

  5. Study on mercury migration in a circulating fluidized bed combustion boiler%循环流化床燃煤锅炉中的汞迁移研究

    Institute of Scientific and Technical Information of China (English)

    武成利; 曹晏; 李寒旭; 潘伟平

    2012-01-01

    采用美国环保署颁布的吸附剂吸附汞采样方法30B(USEPA 40 CFR Part 60 30B)采集燃煤烟气中汞.选择一循环流化床燃煤机组进行现场采样,吸附剂吸附烟囱处烟气中的汞、入炉煤样、锅炉底灰、静电除尘器飞灰等样品同时采集.对该机组中汞质量平衡率进行衡算,通过汞质量平衡率说明了汞采样方法的准确性和有效性.评价了汞在飞灰、底灰和烟气中的分布,循环流化床锅炉底灰中对脱汞的贡献率仅0.55%,飞灰脱除汞的效率高达83.37%,剩余的16.08%的汞排放入大气环境,表明循环流化床机组是有效控制汞的清洁煤燃烧技术.%Mercury concentrations in the flue gas at the stack were measured using a sorbent trap method as per United States Environmental Protection Agency Method 30B (I. E. , USEPA 40 CFR Part 60 30B), and the sampling method has merits of convenient setup, simply operation and fast analysis. Field tests were conducted at a unit of the Circulating Fluidized Bed Combustion (CFBC). During the course of sampling the mercury in the flue gas, coal samples, bottom ash and fly ash were collected and analyzed. Rates of mercury material balance though the unit were calculated, and correctness and validity of mercury sampling method were certified. Mercury distributions in fly ash, bottom ash and flue gas were evaluated, and the results showed that firstly bottom ash of CFBC removed only 0. 55% of total mercury, secondly removal efficiency of fly ash reaching 83. 37% , in the end 16.08% of total mercury was emitted to the air. The determined data of mercury emissions show that the CFBC is a clean coal combustion technology of effectively removing mercury.

  6. Water softening by induced crystallization in fluidized bed.

    Science.gov (United States)

    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.

  7. Effects of Immersed Surfaces on the Combustor Efficiency of Small-Scale Fluidized Beds

    OpenAIRE

    Nurdil Eskin; Afsin Gungor

    2005-01-01

    In this study, effects of the different types of heat exchanger surfaces on the second law efficiency of a small-scale circulating fluidized bed (CFB) combustor are analyzed and the results are compared with the bubbling fluidized bed coal combustor effectiveness values. Using a previously developed simulation program, combustor efficiency and entropy generation values are obtained at different operation velocities at different height and volume ratios of the immersed surfaces, both for circu...

  8. Numerical modelling 2 D and 3 D of circulating fluidized bed: application to the realization of regime diagrams; Modelisation numerique 2D et 3D de lit fluidise circulant: application a la realisation du diagramme des regimes

    Energy Technology Data Exchange (ETDEWEB)

    Begis, J.; Balzer, G.

    1997-02-01

    The numerical modelling of internal CFB boilers flows faced with complex phenomenons due to the flows un-stationariness, the heterogeneousness of the particle size distribution, and interactions between the two phases and the walls. Our study consisted in applying numerical models to the experimental configuration of cold circulating fluidized bed studied at the Cerchar. Special attention was given to the analysis of particles - wall interactions models, stemming from Jenkins (1992) and Louge`s (1994) theories, as well as the influence of the particles on fluid turbulence. In order to realize numerical simulations, we have used Eulerian two-phases flow codes developed at NHL medolif(2D), ESTET-ASTRID(3D). From different tests we have deducted that the most appropriate model for the realization of CFB`s prediction is the model taking in account the influence of particles on fluid turbulence. Then, to evaluate the validity limits of this model, we have built the regime diagram, and we have compared it with the experimental diagram. We have concluded that the simulation allows to describe the different CFB`s working regimes, and especially transitions. We have also noticed the importance of the choice of the mean diameter of the simulated particles. In this way, making a correction of the simulated particles` diameter in comparison with Sauter mean particle diameter, we obtained numerical results in good agreement with experimental data. (authors) 13 refs.

  9. Study of the behaviour of gaseous pollutants during the incineration of municipal solid waste in a circulating fluidized bed; Etude du devenir des polluants gazeux lors de l`incineration d`ordures menageres en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Desroches-Ducarne, E.

    1997-09-30

    The Circulating Fluidized Bed (CFB) combustor seems to be a promising tool, being able to burn a variety of fuels whilst maintaining low emissions levels. The present work describes an experimental and theoretical investigation into the formation and destruction of acid gases (HCl and SO{sub 2}) and nitrogen oxides (NO and N{sub 2}O) during Municipal Solid Waste incineration. Experiments were conducted on six different fuels (namely MSW, mixtures of wood, paper, plastics, polyethylene...). The effect of five parameters (temperature, excess air, air staging, calcium addition and moisture) on the emissions levels was investigated. A statistical study on the experimental data allowed us to quantify the impact of the operating conditions and the influence of the fuel characteristics. A mathematical model has been developed which includes the main physical and chemical steps of combustion in CFB and which predicts the pollutant emissions under various operating conditions. A parametric study of the influence of operating conditions on emissions showed that in most cases the trends predicted by the model are in agreement with the experimental observations. (author) 175 refs.

  10. Technology approach to improve the amount of steam of circulating fluidized bed boiler%提高循环流化床锅炉产汽量的技术途径

    Institute of Scientific and Technical Information of China (English)

    赵代林

    2015-01-01

    循环流化床炉属于新型节能先进锅炉,我厂于1996年和2003年安装两台35t/h的循环流化床锅炉,经过几年的运行,锅炉产汽量逐渐降低,特别是煤源发生变化后,锅炉产汽量由25t/h左右降至不足15t/h。本文针对锅炉产汽量低的原因,进行了系统的研究探讨,提出了合理建议,并进行技术改造,应用于生产实际中。%Circulating fluidized bed boiler is a kind of new energy-saving boiler. There were two circulating fluidized bed boiler in our plant. After running for several years,the amount of steam deceased gradually. Especially,the amount of steam was not less than 15t/h from 25 t/h after the change of coal. Combining with this problems,the reasons were diccussed and the suggestions were put forward. The revamping measures were carried on.

  11. Biological denitrification in a fluidized bed.

    Science.gov (United States)

    Narjari, N K; Khilar, K C; Mahajan, S P

    1984-12-01

    A fluidized bed biofilm reactor using sand as the carrier particle was employed to study the effects of superficial velocity on the removal of nitrates as well as on the growth of the biofilm. Velocity was found to affect significantly both nitrate removal and biofilm growth. An analysis based on heterogenous catalysis was used to describe the denitrification process. There is good agreement between analysis and experimental measurements for startup and steady-state operating conditions.

  12. Commissioning and Analysis of Integrative Sewage Sludge Incineration Demonstration Project with Circulating Fluidized Bed%循环流化床一体化污泥焚烧工程的调试及分析

    Institute of Scientific and Technical Information of China (English)

    吕清刚; 朱建国; 李诗媛; 李云玉; 那永洁; 包绍麟; 丁艳辉; 黄毅

    2012-01-01

    To investigate the feasibility of using incineration technology to treat excess sludge from WWTP, a sewage sludge incineration demonstration project with capacity of 100 t/d in Qige Sewage Treatment Plant of Hangzhou City was constructed, and the cold and hot commissionings were conducted. The 'old commissioning results showed that the monitoring data of key equipments, such as screw convey-incinerator and complex fluidized bed dryer, agreed well with the design values. The hot commissioning rerults indicated that the temperature was uniform in the complex fluidized bed dryer where the sewage sludge with 79% to 80% moisture content could be well dried and crushed, and the maximal diameter of dried sludge particles was 3 mm with the 50% cut size of 0. 32 mm. The dried sludge was immediately transported into the circulating fluidized bed incinerator with the incineration temperature of 860 t.It is concluded that the technology for integrative drying and incineration of sewage sludge in circulating fluidized bed an be applied in engineering projects.%为探索采用焚烧工艺处理污水厂剩余污泥的可行性,在杭州市七格污水处理厂建设了规模为100 t/d的污泥焚烧处理示范工程,并进行了冷、热态调试.冷态调试结果表明,系统关键设备如干污泥螺旋输送机、焚烧炉、复合干化器等的测试数据与设计值吻合.热态调试结果显示,复合干化器内温度均匀,含水率为79%~80%的湿污泥在复合干化器内破碎和干燥程度良好,干污泥颗粒最大直径为3 mm,50%的切割粒径为0.32 mm.干污泥即时进入循环流化床焚烧炉焚烧,焚烧温度为860℃.可见,采用循环流化床一体化焚烧技术处理污泥在工程上是可行的.

  13. Fluidized Bed Asbestos Sampler Design and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Karen E. Wright; Barry H. O' Brien

    2007-12-01

    A large number of samples are required to characterize a site contaminated with asbestos from previous mine or other industrial operations. Current methods, such as EPA Region 10’s glovebox method, or the Berman Elutriator method are time consuming and costly primarily because the equipment is difficult to decontaminate between samples. EPA desires a shorter and less costly method for characterizing soil samples for asbestos. The objective of this was to design and test a qualitative asbestos sampler that operates as a fluidized bed. The proposed sampler employs a conical spouted bed to vigorously mix the soil and separate fine particulate including asbestos fibers on filters. The filters are then analyzed using transmission electron microscopy for presence of asbestos. During initial testing of a glass prototype using ASTM 20/30 sand and clay fines as asbestos surrogates, fine particulate adhered to the sides of the glass vessel and the tubing to the collection filter – presumably due to static charge on the fine particulate. This limited the fines recovery to ~5% of the amount added to the sand surrogate. A second prototype was constructed of stainless steel, which improved fines recovery to about 10%. Fines recovery was increased to 15% by either humidifying the inlet air or introducing a voltage probe in the air space above the sample. Since this was not a substantial improvement, testing using the steel prototype proceeded without using these techniques. Final testing of the second prototype using asbestos suggests that the fluidized bed is considerably more sensitive than the Berman elutriator method. Using a sand/tremolite mixture with 0.005% tremolite, the Berman elutriator did not segregate any asbestos structures while the fluidized bed segregated an average of 11.7. The fluidized bed was also able to segregate structures in samples containing asbestos at a 0.0001% concentration, while the Berman elutriator method did not detect any fibers at this

  14. Single-stage fluidized-bed gasification

    Science.gov (United States)

    Lau, F. S.; Rue, D. M.; Weil, S. A.; Punwani, D. V.

    1982-04-01

    The single-stage fluidized-bed gasification process, in addition to being a simple system, maximizes gas production and allows the economic exploitation of small peat deposits. The objective of this gasification project is to conduct experiments in order to obtain data for designing a single-stage fluidized-bed gasifier, and to evaluate the economics of converting peat to synthesis gas and to SNG by this process. An existing high-temperature and high-pressure process development unit (PDU) was modified to permit the direct feeding of peat to the fluidized bed. Peat flows by gravity from the feed hopper through a 6-inch line to the screw-feeder conveyor. From there, it is fed to the bottom tee section of the reactor and transported into the gasification zone. Oxygen and steam are fed through a distributing ring into the reactor. Gasification reactions occur in the annulus formed by the reactor tube and a central standpipe. Peat ash is discharged from the reactor by overflowing into the standpipe and is collected in a solids receiver.

  15. Status of the fluidized bed unit

    Energy Technology Data Exchange (ETDEWEB)

    Williams, P.M.; Wade, J.F.

    1994-06-01

    Rocky Flats has a serious mixed waste problem. No technology or company has a license and available facilities to remedy this dilemma. One solution under study is to use a catalytic fluidized bed unit to destroy the combustible portion of the mixed waste. The fluidized bed thermal treatment program at Rocky Flats is building on knowledge gained over twenty years of successful development activity. The FBU has numerous technical advantages over other thermal technologies to treat Rocky Flats` mixed waste, the largest being the lower temperature (700{degrees}C versus 1000{degrees}C) which reduces acid corrosion and mechanical failures and obviates the need for ceramic lining. Successful demonstrations have taken place on bench, pilot, and full-scale tests using radioactive mixed wastes. The program is approaching implementation and licensing of a production-scale fluidized bed system for the safe treatment of mixed waste. The measure for success on this project is the ability to work closely with the community to jointly solve problems and respond to concerns of mixed waste treatment at Rocky Flats.

  16. Novel designs of fluidized bed combustors for low pollutant emissions

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W.; Bleek, C.M. van den [Delft Univ. of Technology (Netherlands). Dept. of Chemical Engineering; Dam-Johansen, K. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering

    1995-12-31

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

  17. Fluidized Bed Sputtering for Particle and Powder Metallization

    Science.gov (United States)

    2013-04-01

    Fluidized Bed Sputtering for Particle and Powder Metallization by Daniel M. Baechle, J. Derek Demaree, James K. Hirvonen, and Eric D...5069 ARL-TR-6435 April 2013 Fluidized Bed Sputtering for Particle and Powder Metallization Daniel M. Baechle, J. Derek Demaree, James K...YYYY) April 2013 2. REPORT TYPE Final 3. DATES COVERED (From - To) June 2008–June 2012 4. TITLE AND SUBTITLE Fluidized Bed Sputtering for

  18. Exergy efficiency analysis on large-scale circulating fluidized bed boilers%大型循环流化床锅炉火用效率分析

    Institute of Scientific and Technical Information of China (English)

    刘彦鹏; 钟北京; 李少华

    2015-01-01

    On the basis of boiler exergy balance mathematical model,the exergy efficiency and each exergy loss of large-scale circulating fluidized bed (CFB)boilers was analyzed.The results show that,the total ex-ergy loss of combustion and heat transfer of the CFB boiler was over 45% of the fuel chemical exergy, which is the main exergy loss of the CFB boiler.Increasing the power unit capacity and steam parameters can increase the average heat absorption temperature of the water in furnace,thus to reduce the heat trans-fer exergy loss of the boiler effectively.The exhaust exergy loss rate was about 1%,which is greatly smal-ler than that of the exhaust heat loss rate,but there's still potential to be tapped.For CFB boilers,the exer-gy loss rate during combustible gas incomplete combustion and heat transfer can be ignored.The unburned carbon exergy loss,which is the chemical exergy of the unburned carbon,should be paid more attention to be reduced due to its high quality.The CFB boiler slag has a high proportion of coal ash,so reducing the slag physical exergy loss has great significance to improving the CFB boiler efficiency.%采用锅炉火用平衡数学模型,对大型循环流化床(CFB)锅炉的各项火用损失和火用效率进行了分析,并以某亚临界300 MW机组CFB锅炉为对象,进行了实例计算,并对不同参数等级CFB锅炉进行了火用效率分析。结果表明:CFB锅炉的燃烧和传热火用损失之和占燃料化学火用的45%以上,是锅炉的主要火用损失;提高机组容量和蒸汽参数,可以提高炉水平吸热温度,从而有效降低锅炉传热火用损失;锅炉排烟火用损失率在1%左右,比排烟热损失率小很多;CFB锅炉的可燃气体未完全燃烧火用损失率、散热火用损失率均可忽略不计;固体未完全燃烧火用损失由于损失的是未燃尽碳的化学火用,其热能品位较高,因此应重点采取措施减小该项损失;CFB锅炉炉渣占煤

  19. Research on the Foamed Concrete Matrix Materials with Circulating Fluidized Bed Fly Ash%固硫灰泡沫混凝土的基材研究

    Institute of Scientific and Technical Information of China (English)

    陈雪梅; 严云; 胡志华

    2013-01-01

    以熟科(30%)-固硫灰(70%)做基体,研究了在不同养护方式下,生石灰、铝酸盐水泥单掺及复掺时对基体强度、凝结时间、膨胀性能的影响.结果表明,在熟料-固硫灰系统中加入生石灰可激发固硫灰活性、加快浆体稠化,提高后期强度并增加膨胀.单掺2%铝酸盐水泥的基体强度最高,但当与生石灰复掺时,基体凝结时间会进一步缩短且强度降低,但膨胀增加显著.蒸养有利于基体强度发展并能有效限制膨胀,其膨胀率约为标养的20%.在生石灰掺量为8%,铝酸盐水泥掺量为2%和60℃蒸气养护1d的条件下,可以制备出容重为393 kg/m3,强度2.1 MPa且性能合格的固硫灰泡沫混凝土.%Effect of curing regimes and admixtures including lime and aluminate cement as single and compound admixture on properties (strength,setting time and expansion) of matrix was investigated,when circulation fluidized bed combustion (CFBC) fly ash (70%,by weight) and cement clinker(30%,by weight) were used as cementitious materials in developing foam concrete.The results indicate that lime in cement-clinker system can excite the activity of CFBC fly ash,accelerate the thickening of slurry,improve long term strength and increase expansion.The strength of matrix with 2% aluminate cement is the highest.However,in the presence of lime,the strength decreased,expansion significantly increased and setting time was shortened with the increasing of aluminate cement.Steam curing is beneficial for the strength development and can restrict expansion effectively,which is 20% of that of standard curing.Based on the research of matrix,adding 2% aluminate cement,8% quick lime and curing in the circumstance of 60 ℃ for 24 h,the foam concrete with compressive strength achieving 2.1 MPa and the bulk density of 393 kg/m3 were prepared and its comprehensive performances are good.

  20. Combustion of low grade fractions of Lubnica coal in fluidized bed

    Directory of Open Access Journals (Sweden)

    Mladenović Milica R.

    2012-01-01

    Full Text Available In this paper a method of examination of fuel suitability for fluidized bed combustion is presented. The research of combustion characteristics of low grade fractions of Lubnica brown coal in the fluidized bed by the aforementioned methodology has been carried out on a laboratory semi-industrial apparatus of 200 kWt. Description of the experimental fluidized bed combustion facility is given, as well as experimental results, with the focus on furnace temperature distribution, in order to determine the location of the zone of intensive combustion. Based on investigation results, which are focused on combustion quality (combustion completion as well as on satisfying the environmental protection criteria, it can be stated that the investigated coal is suitable for burning in bubbling, as well as in circulating fluidized bed.

  1. Pulsed atmospheric fluidized bed combustion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    ThermoChem, under contract to the Department of Energy, conducted extensive research, development and demonstration work on a Pulsed Atmospheric Fluidized Bed Combustor (PAFBC) to confirm that advanced technology can meet these performance objectives. The ThermoChem/MTCI PAFBC system integrates a pulse combustor with an atmospheric bubbling-bed type fluidized bed combustor (BFBC) In this modular configuration, the pulse combustor burns the fuel fines (typically less than 30 sieve or 600 microns) and the fluidized bed combusts the coarse fuel particles. Since the ThermoChem/MTCI PAFBC employs both the pulse combustor and the AFBC technologies, it can handle the full-size range of coarse and fines. The oscillating flow field in the pulse combustor provides for high interphase and intraparticle mass transfer rates. Therefore, the fuel fines essentially burn under kinetic control. Due to the reasonably high temperature (>1093 C but less than the temperature for ash fusion to prevent slagging), combustion of fuel fines is substantially complete at the exit of the pulse combustor. The additional residence time of 1 to 2 seconds in the freeboard of the PAFBC unit then ensures high carbon conversion and, in turn, high combustion efficiency. A laboratory unit was successfully designed, constructed and tested for over 600 hours to confirm that the PAFBC technology could meet the performance objectives. Subsequently, a 50,000 lb/hr PAFBC demonstration steam boiler was designed, constructed and tested at Clemson University in Clemson, South Carolina. This Final Report presents the detailed results of this extensive and successful PAFBC research, development and demonstration project.

  2. Experimental Study on Coal Multi-generation in Dual Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    Fan Xiaoxu; Lu Qinggang; Na Yongjie; Liu Qi

    2007-01-01

    An atmospheric test system of dual fluidized beds for coal multi-generation was built. One bubbling fluidized bed is for gasification and a circulating fluidized bed for combustion. The two beds are combined with two valves:one valve to send high temperature ash from combustion bed to the gasification bed and another valve to send char and ash from gasification bed to combustion bed. Experiments on Shenhua coal multi-generation were made at temperatures from 1112 K to 1191 K in the dual fluidized beds. The temperatures of the combustor are stable and the char combustion efficiency is about 98%. Increasing air/coal ratio to the fluidized bed leads to the increase of temperature and gasification efficiency. The maximum gasification efficiency is 36.7% and the calorific value of fuel gas is 10.7 MJ/Nm3. The tar yield in this work is 1.5%, much lower than that of pyrolysis.Carbon conversion efficiency to fuel gas and flue gas is about 90%.

  3. 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

    Directory of Open Access Journals (Sweden)

    Alamin Ahmed Hassan

    2016-06-01

    Full Text Available 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.

  4. Tube erosion in bubbling fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Levy, E.K. [Lehigh Univ., Bethlehem, PA (United States). Energy Research Center; Stallings, J.W. [Electric Power Research Inst., Palo Alto, CA (United States)

    1991-12-31

    This paper reports on experimental and theoretical studies that were preformed of the interaction between bubbles and tubes and tube erosion in fluidized beds. The results are applicable to the erosion of horizontal tubes in the bottom row of a tube bundle in a bubbling bed. Cold model experimental data show that erosion is caused by the impact of bubble wakes on the tubes, with the rate of erosion increasing with the velocity of wake impact with the particle size. Wake impacts resulting from the vertical coalescence of pairs of bubbles directly beneath the tube result in particularly high rates of erosion damage. Theoretical results from a computer simulation of bubbling and erosion show very strong effects of the bed geometry and bubbling conditions on computed rates of erosion. These results show, for example, that the rate of erosion can be very sensitive to the vertical location of the bottom row of tubes with respect to the distributor.

  5. Formation and destruction mechanisms of nitrogen oxides during coal combustion in circulating fluidized beds; Mecanismes de formation et de destruction des oxydes d`azote lors de la combustion du charbon en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Borrel, G.; Lecuyer, I. [Universite du Haut-Rhin, 68 - Mulhouse (France)

    1997-01-01

    Formation and reduction of nitrogen oxides (NO and N{sub 2}O) during coal combustion in a circulating fluidized bed (CFBC) are very complicated and yet badly known. The aim of the present study was to better characterize these phenomena on a small-sized experimental unit (reactor diameter: 5 cm), with the possibility to re-inject the solids in the bottom of the furnace, as in a real industrial unit. This should allow then to develop a numerical set of chemical reactions involving the nitrogen oxides. The experimental results showed that coal ash plays a great role in reducing nitrogen oxides, the determining parameter being the quantity of unburnt carbon remaining in the ash. The study then detailed the interaction between nitrogen oxides and de-volatilized (char) according to the temperature, NO{sub x} concentration and the mass of solid. In the absence of oxygen small quantities of char can very significantly reduce NO as well as N{sub 2}O. It was possible to establish destruction kinetics on these particles, and orders of reaction could be determined versus the NO{sub x} concentration and the char particle mass (heterogeneous phase chemical reactions). Then, the coal pyrolysis study enabled to identify the products released during coal devolatilization and thermogravimetric analyses displayed several successive weight losses due CO, CO{sub 2} and CH{sub 4} releases, during a linear temperature increase. Lastly coal combustion was studied in the small pilot with variable experimental conditions. Using the previous experimental was studied in the small pilot with variable experimental conditions. Using the previous experimental results, a model was developed to calculate NO{sub x} concentrations during the coal combustion and validated. The NO and N{sub 2}O contents calculated are thoroughly correlated with the experimental data whatever the injection carbon/oxygen ratio is. (author) 96 refs.

  6. Experimental study of spiral flow generator in liquid-solid horizontal circulating fluidized bed%水平液固循环流化床起旋器的实验研究

    Institute of Scientific and Technical Information of China (English)

    彭培英; 张伟; 刘燕

    2009-01-01

    An experiment was made of the particles distribution of each section of a single-loop solids circulation system in a φ29 mm×4 200 mm cold liquid-solid horizontal circulating fluidized bed test facility. The CCD image measurement and data processing system was used to study the particles distribution at different operating conditions with the spiral flow generator added.The experiment shows that the spiral pipe flow generator arranged in the liquid-solid horizontal circulating fluidized bed can effectively improve the uniform distribution of particles in a certain distance; but as the axial distance increases, the effect of the spiral flow generator weakened. There was a low non-uniform distribution as the guide vane angle and liquid flow rate increased. For the particle with the same diameter, density and initial volume add the larger the solid particles containing the greater rate of non-uniform degrees.%在φ29 mm×4 200 mm流化床装置上,利用CCD图像测量与数据处理系统在线对导流叶片式局部起旋器对水平液固循环流化床内固相颗粒分布特性的影响进行了研究.结果表明:安装局部起旋器后,颗粒分布状况在一定距离内得到明显改善;但随着轴向距离增加,起旋器作用效果减弱.随着导叶包角、液体流速的增加,颗粒固含率不均匀度减小.对于相同直径的颗粒,密度和初始加入量越大,颗粒固含率不均匀度越大.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, B.N.; Shchipko, M.L.; Golovin, Yu. [Inst. of Chemistry of Natural Organic Materials, Academgorodok, Krasnoyarsk (Russian Federation)

    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.

  8. SIMULATION OF PARTICLE COATING IN THE SUPERCRITICAL FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    Carsten; Vogt; Ernst-Ulrich; Hartge; Joachim; Werther; Gerd; Brunner

    2005-01-01

    Fluidized bed technology using supercritical carbon dioxide both as a fluidizing gas and as a solvent for the coating material makes possible the production of thin, uniform and solvent-free coatings. But operation at low fluidizing velocities, which is favorable to facilitate gas cleaning under the high pressure conditions, may lead to uneven distribution of the coating in the fluidized bed and to unstable operation due to agglomeration. Therefore a model has been developed which describes local fluid dynamics within the high pressure fluidized bed. Based on this model, the coating process is described and the distribution of the coating inside the fluidized bed is calculated. Furthermore a submodel for the calculation of local concentrations of liquid paraffin has been set up, which may be used as a basis for the prediction of agglomeration and thus stability of operation.

  9. CFD study of a fluidized bed

    OpenAIRE

    Lundberg, Joachim

    2008-01-01

    The aim of this thesis is to investigate the momentum exchange between the phases in a bubbling fluidized bed. The momentum exchange can be described by a drag model. Several drag models with different assumptions are developed. The drag models investigated in this work is the Syamlal O’Brien model, the Gidaspow model, Hill Koch Ladd model, the RUC model and an iterative version of the Syamlal O’Brien called the Richardson Zaki model. The models have been derived and studied in de...

  10. PREDICTION OF FLOW REGIMES IN SPOUT-FLUIDIZED BEDS

    Institute of Scientific and Technical Information of China (English)

    Jiyu Zhang; Fengxiang Tang

    2006-01-01

    Five main flow regimes in spout-fluidized bed were identified in this study, namely, fixed bed, spout with aeration, spout-fluidization, jet in fluidized bed and slugging, together with their corresponding major frequencies translated from pressure signals. The empirical equation A=aBb, in which A=Fr* /(H/Di) and B=(Fr*/(H/D))/(μg/μmf) are respectively the spout-geometry and spout-geometry-fluidization dimensionless numbers, was proposed to distinguish these flow regimes.

  11. Starts circulating ash of circulating fluidized bed boiler is too little, can't load cause analysis and suggestion%循环流化床锅炉启动后循环灰少的原因及改进措施

    Institute of Scientific and Technical Information of China (English)

    师克宁

    2016-01-01

    For analysis of the problem after the start because of circulating fluidized bed boiler circulating ash too small to quickly bring up loads of fluidized bed boiler optimization and initial start-up and running adjustments to make recommendations and to take measures to reduce startup time with full load improve mobility fluidized bed boiler, the boiler plant to improve safety, economy and environmental protection.%针对循环流化床锅炉启动后因循环灰量太少无法快速带起负荷的问题进行分析,对流化床锅炉优化启动和启动初期运行调整提出建议,并采取措施缩短启动到带满负荷的时间,提高流化床锅炉运行机动性,达到提高电厂锅炉运行的安全性、经济性和环保性.

  12. Some hydrodynamic aspects of 3-phase inverse fluidized bed

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Hydrodynamics of 3-phase inverse fluidized bed is studied experimentally using low density particles for different liquid and gas velocities.The hydrodynamic characteristics studied include pressure drop, minimum liquid and gas fluidization velocities and phase holdups. The minimum liquid fluidization velocity determined using the bed pressure gradient, decreases with increase in gas velocity. The axial profiles of phase holdups shows that the liquid holdup increases along the bed height, whereas the solid holdup decreases down the bed. However, the gas holdup is almost uniform in the bed.

  13. Simultaneous reduction of SO{sub 2} and N{sub 2}O from a fluidized bed combustor without increasing NO{sub x} emission using fine sorbent circulation

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, T.; Satoh, M.; Fujikawa, T.; Sato, K.; Tonsho, M.; Inagaki, M. [Niigata Univ., Niigata (Japan). Dept. of Chemistry and Chemical Engineering

    2002-07-01

    This paper proposes a method to reduce nitrogen oxide (NO{sub x}) and sulphur dioxide (SO{sub 2}) emissions from a two-stage fluidized bed combustor in which fuel combustion is conducted in the lower bed and SO{sub 2} is captured from the flue gas in the upper bed. In particular, the study focused on the problem of increased NO{sub x} emissions resulting from in situ SO{sub 2} capture by sorbent limestone feed in a fluidized bed coal combustor. The study examined if the reduction in limestone size can suppress the increase in NO{sub x} emissions. It also examined how the reduction of nitrous oxide (N{sub 2}O) emission by limestone feed is affected by the size of the limestone. The increase in NO{sub x} is caused by oxidation of volatile-N components such as ammonia and hydrogen cyanide, which are released during coal devolatilization. It was suggested that NO{sub x} emissions can be controlled by separating the combustion zone from the desulfurization zone. This paper also describes a process to burn coarse coal in a bubbling fluidized bed and where the sorbent removed fines are then separated from the combustion coal. The removal of SO{sub 2} after combustion avoids an increase in NO{sub x} which would normally occur due to sorbent contact with volatile nitrogen. N{sub 2}O can be decomposed to nitrogen catalyzed by the sorbent in the freeboard. In terms of the effect of sorbent size on the relationship between NO{sub x} emissions and SO{sub 2} removal, the study showed that a large sorbent increased NO{sub x} emissions while a reduced sorbent size avoided an increased in NO{sub x} emissions. N{sub 2}O reduction by SO{sub 2} removal was observed. Sorbent-circulating FBC was found to be effective for reducing SO{sub 2} and N{sub 2}O without increasing NO{sub x}. 17 refs., 2 tabs., 6 figs.

  14. Collecting aerosol in airflow with a magnetically stabilized fluidized bed

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A magnetically stabilized fluidized bed (MSB) is a highly efficient filter that takes the advantage of both fluidized beds and fixed beds. This paper presents the research to collect aerosol in airflow with a MSB. The filtering model of MSB is established with its parameters including magnetic field intensity,gas superficial velocity, average grain-size, and bed height on thecollection efficiency of MSB. The model is verified by experiments.

  15. Particle transport in fluidized beds : experiments and stochastic models

    NARCIS (Netherlands)

    Dechsiri, Chutima

    2004-01-01

    Fluidization is a process in which solids are caused to behave like fluid by blowing gas or liquid upwards through the solid-filled reactor. The behavior of a bed of particles within the reactor during the process is very complex and difficult to predict. To make sure that a fluidized bed reactor is

  16. State of the art and the future fuel portfolio of fluidized bed combustion systems; Status und kuenftiges Brennstoffportfolio bei Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Szentannai, Pal; Friebert, Arpad; Winter, Franz [Technische Univ. Wien (Austria). Inst. fuer Verfahrens-, Umwelttechnik und technische Biowissenschaften

    2008-07-01

    Coal, biomass and substitute fuels energetically can be used efficiently and with low pollution in fluidized bed plants. In comparison to biomass there are significant differences between the circulating and stationary fluidized bed technology. The stationary fluidised bed is fed predominantly with biomasses and residual substances. Coal usually is the basis fuel in the circulating fluidised bed. Biomass and residual substances frequently are course-fired. The state of the art is the employment of a broad fuel mixture in small and large fluidized-bed combustion systems. Future developments present an increased use of sewage sludge, fluidized bed combustion systems with wood as a basis fuel, utilization of household waste and the gas production.

  17. Stabilizing effect of plasma discharge on bubbling fluidized granular bed

    Science.gov (United States)

    Hu, Mao-Bin; Dang, Sai-Chao; Ma, Qiang; Xia, Wei-Dong

    2015-07-01

    Fluidized beds have been widely used for processing granular materials. In this paper, we study the effect of plasma on the fluidization behavior of a bubbling fluidized bed with an atmospheric pressure plasma discharger. Experiment results show that the bubbling fluidized bed is stabilized with the discharge of plasma. When the discharge current reaches a minimum stabilization current Cms, air bubbles in the bed will disappear and the surface fluctuation is completely suppressed. A simplified model is proposed to consider the effect of electric Coulomb force generated by the plasma. It is found that the Coulomb force will propel the particles to move towards the void area, so that the bubbling fluidized bed is stabilized with a high enough plasma discharge. Project supported by the National Natural Science Foundation of China (Grant Nos. 11035005 and 11034010).

  18. Application of Selective Non-catalytic Reduction Denitration Technology in Circulating Fluidized Bed Boiler%选择性非催化还原脱硝技术在循环流化床锅炉中的应用

    Institute of Scientific and Technical Information of China (English)

    柳振

    2016-01-01

    针对中国石化上海石油化工股份有限公司(以下简称上海石化)620 t/h循环流化床锅炉效率偏低及氮氧化物排放质量浓度不能达到环保排放标准的现状,在炉内燃烧脱硝技术的基础上,通过实施锅炉尾部烟气脱硝改造,采用当前先进的选择性非催化还原(SNCR)脱硝技术,进一步提该锅炉的脱硝水平。同时通过设计、模拟和应用的对比研究,总结出SNCR脱硝技术在循环流化床锅炉上使用的适应性和进一步提高效率的必要性。%In view that the productivity and concentration of NOx emission of the 620 t/h circulating fluidized bed boiler in SINOPEC Shanghai Petrochemical Co.,Ltd.(hereinafter referred to as SPC ) cannotmeet the environmental protection emission standards,the denitration performance of the boiler was improved though denitration process transformation of increasing the boiler flue gas,adopting the state-of-the-art selective non -catalytic reduction (SNCR ) technology on the basis of thedenitration technologyof in -boiler combustion.Meanwhile,through study of the technology in 7#boiler of Thermal Power Station of SPC,the adaptability of SNCR denitration technology in circulating fluidized bed boiler and the necessity of further improving efficiency were summarized.

  19. Simulations of a Circulating Fluidized Bed Chemical Looping Combustion System Utilizing Gaseous Fuel Simulation de la combustion en boucle chimique d’une charge gazeuse dans un lit fluidisé circulant

    Directory of Open Access Journals (Sweden)

    Mahalatkar K.

    2011-05-01

    Full Text Available Numerical studies using Computational Fluid Dynamics (CFD have been carried out for a complete circulating fluidized bed chemical looping combustor described in the literature (Abad et al., 2006 Fuel 85, 1174-1185. There have been extensive experimental studies in Chemical Looping Combustion (CLC, however CFD simulations of this concept are quite limited. The CLC experiments that were simulated used methane as fuel. A 2-D continuum model was used to describe both the gas and solid phases. Detailed sub-models to account for fluid-particle and particleparticle interaction forces were included. Global models of fuel and carrier chemistry were utilized. The results obtained from CFD were compared with experimental outlet species concentrations, solid circulation rates, solid mass distribution in the reactors, and leakage and dilution rates. The transient CFD simulations provided a reasonable match with the reported experimental data. Des études numériques de simulation des écoulements (CFD ont été réalisées sur un lit fluidisé circulant opérant en combustion par boucle chimique (CLC décrit dans la littérature (Abad et al., 2006 Fuel 85, 1174-1185. Si de nombreuses études expérimentales ont été conduites pour étudier le procédé CLC, les études concernant la simulation des écoulements par CFD de ce concept sont très limitées. Le système de combustion en boucle chimique simulé dans cette étude concerne la combustion d’une charge gazeuse (méthane. Un modèle 2-D à deux phases continues a été utilisé pour décrire les phases gaz et solide avec des sous-modèles détaillés pour décrire les forces d’interactions entre fluideparticule et particule-particule. Des modèles cinétiques globaux ont été intégrés pour décrire les réactions de combustion et de transformation du matériau transporteur d’oxygène. Les résultats obtenus par CFD ont été comparés aux concentrations expérimentales mesurées des diff

  20. 影响循环流化床锅炉燃烧热效率的因素和提高途径%Factors Affecting Combustion Thermal Efficiency of Circulating Fluidized Bed Boiler and Ways to Improve

    Institute of Scientific and Technical Information of China (English)

    李敬珂

    2015-01-01

    In order to find out ways and measures to improve combustion thermal efficiency of boiler,combustion adjustment test for circulating fluidized bed boiler is carried out,factors affecting combustion thermal efficiency of boiler, including oxygen content in flue gases, bed pressure differential,bed temperature,operating load,carbon content in cinder and so on,are analyzed and summed-up.With test data,ways to improve combustion thermal efficiency of boiler,countermeasures and suggestions are proposed.%为找出提高锅炉燃烧热效率的途径和措施,对循环流化床锅炉进行了燃烧调整试验,分析并总结了烟气氧含量、床层压差、床层温度、运行负荷、煤灰中的碳含量等因素对锅炉燃烧热效率的影响。通过试验数据,提出了提高锅炉燃烧热效率的途径、改进措施和建议。

  1. RESEARCH ON DENSITY STABILITY OF AIR DENSE MEDIUM FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    骆振福; 陈清如

    1994-01-01

    In this papcr on thc basis of studying the distribution of fine coal in the dense medium fluidized bed, the optimal size range of fine coal, which constitutes a fluidized bed together with the dense medium, has been found. In the separating process the fine coal will continuously accumulate in fluidized bed, thus inevitably reducing the density of the bed. In order to keep bed density stable, the authors adopted such measures as split-flow of used medium and complement of fresh dense medium. The experiment results in both lab and pilot systems of the air-dense medium fluidized bed show that these measures are effective and satisfactory. Then authors also have established some relative dynamic mathematical models for it.

  2. A Cold Model Experimental Study on the Flow Characterisitcs of Bed Baterial in A Fluidized ed Bottom Ash Cooler in a CFB Boiler

    Institute of Scientific and Technical Information of China (English)

    LuXiaofeng; LiYourong

    2000-01-01

    A cold model experimental study on the flowing characteristics of bed meterial 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.

  3. Fluidized-bed calciner with combustion nozzle and shroud

    Science.gov (United States)

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

    1977-01-01

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

  4. 飞灰流化床燃烧脱碳的试验研究%Experimental Study of Fly Ash Decarbonization on a Circulating Fluidized Bed Combustor

    Institute of Scientific and Technical Information of China (English)

    梅琳; 卢啸风; 王泉海; 潘智; 杨宇; 洪勇; 方纯全; 郭宏; 阳向东

    2014-01-01

    飞灰回燃脱碳效率较低,导致回燃后飞灰仍不能满足综合利用的要求。文中基于飞灰的冷态流化特性,在自行设计的纯然飞灰的热态试验台上进行了燃烧脱碳试验。试验结果表明:CFB 飞灰能够在流化床内连续稳定燃烧,维持炉内燃烧的最小截面热负荷约为0.4MW/m2,对应的临界飞灰含碳量为18%。密相区温度和运行床压对飞灰脱碳均有一定的影响。飞灰燃烧后在底渣的增重份额很小,最大不超过15%。试验系统的最大脱碳效率约为75%,远远高于飞灰回燃的脱碳效率。%ABSTRACT:Because of the huge difference between original boiler operating conditions and fly ash ideal combustion state, the decarbonization effect is disappointed. Consequently, fly ash decarbonization experiments were carried out on a lab-scale CFB combustor designed base on fluidization properties of fly ash and the decarbonization characteristics were presented. Results show that fly ash requires a minimum sectional thermal load of 0.4MW/m2 for continuous and stable combustion in test combustor, the corresponding critical carbon content in the fly ash is 18%. The carbon content in the fly ash is clearly affected by the dense-bed temperature and bed pressure drop during the combustion process. In addition, the fly ash mass fraction in bottom ash does not exceed 15%. The maximum decarbonization efficiency of the test CFB combustor is approximately 75%, which is much higher than that of FARC.

  5. Air Distributor Designs for Fluidized Bed Combustors: A Review

    Directory of Open Access Journals (Sweden)

    A. Shukrie

    2016-06-01

    Full Text Available Fluidized bed combustion (FBC has been recognized as one of the suitable technologies for converting a wide variety of biomass fuels into energy. One of the key factors affecting the successful operation of fluidized bed combustion is its distributor plate design. Therefore, the main purpose of this article is to provide a critical overview of the published studies that are relevant to the characteristics of different fluidized bed air distributor designs. The review of available works display that the type of distributor design significantly affects the operation of the fluidized bed i.e., performance characteristics, fluidization quality, air flow dynamics, solid pattern and mixing caused by the direction of air flow through the distributors. Overall it is observed that high pressure drop across the distributor is one of the major draw backs of the current distributor designs. However, fluidization was stable in a fluidized bed operated at a low perforation ratio distributor due to the pressure drop across the distributor, adequate to provide uniform gas distribution. The swirling motion produced by the inclined injection of gas promotes lateral dispersion and significantly improves fluidization quality. Lastly, the research gaps are highlighted for future improvement consideration on the development of efficient distributor designs.

  6. Kinetics of Reduction Reaction in Micro-Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    LINYin-he; GUOZhan—cheng; TANGHui—qing; REN Shan; LIJing—wei

    2012-01-01

    Micro-fluidized bed reactor is a new research method for the reduction of iron ore fines. The reactor is op- erated as a differential reactor to ensure a constant gas concentration and temperature within the reactor volume. In order to understand the dynamic process of the reduction reaction in micro-fluidized bed, a series of kinetic experi- ments were designed. In the micro fluidized bed, the use of shrinking core model describes the dynamic behavior of reduction of iron ore. And the apparent activation energy is calculated in the range of 700--850 ~C while the initial atmosphere is 100% content of CO.

  7. Research report of FY 1997 on the environmentally acceptable coal utilization system introduction support project. Demonstration project of circulating fluidized bed boiler (Jinzhou Coal-Thermal Power Corporation); 1997 nendo seika hokokusho (kankyo chowagata sekitan riyo system donyu shien jigyo). Junkan ryudosho boiler ni kakawaru jissho jigyo (Jinzhou netsuden sokoji)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    To verify the clean coal technology to be diffused in China and consolidate its diffusion basis, demonstration project of circulating fluidized bed boiler was conducted through the cooperation with China which is positive in its introduction. This report describes its characteristics. Coal and limestone are supplied in a lower part of combustion chamber, and are mixed with circulating ash by fluidized air for combustion. Densely fluidized bed the same as the bubbling fluidized bed is formed in the lower part of combustion chamber, which provides excellent stability in ignition and combustion. Particles including ash, char and limestone formed during the combustion are discharged into the cyclone through the convection heat transfer part at the outlet of combustion chamber with the combustion gas flow. Since the gas temperature is lowered to 400 to 500degC at the convection heat transfer part, troubles of the ash circulating system can be prevented. The combustion gas separated from ash at the cyclone is discharged through the heat exchanger and precipitator, and the collected ash is returned to the lower part of combustion chamber. In FY 1997, design, fabrication, procurement/inspection, field survey/meeting, survey of visitors/meeting, and education were carried out. 4 figs., 4 tabs.

  8. PRESSURE FLUCTUATIONS IN GAS-SOLIDS FLUIDIZED BEDS

    Institute of Scientific and Technical Information of China (English)

    Hsiaotao Bi; Aihua Chen

    2003-01-01

    Pressure fluctuation data measured in a series of fluidized beds with diameters of 0.05, 0.1, 0.29, 0.60 and 1.56 m showed that the maximum amplitude or standard deviation increased with increasing the superficial gas velocity and static bed height for relatively shallow beds and became insensitive to the increase in static bed height in relatively deep beds. The amplitude appeared to be less dependent on the measurement location in the dense bed. Predictions based on bubble passage, bubble eruption at the upper bed surface and bed oscillation all failed to explain all observed trends and underestimated the amplitude of pressure fluctuations, suggesting that the global pressure fluctuations in gas-solids bubbling fluidized beds are the superposition of local pressure variations, bed oscillations and pressure waves generated from the bubble formation in the distributor region, bubble coalescence during their rise and bubble eruption at the upper bed surface.

  9. Effects of sintered metal distributor on fluidization quality of the air dense medium fluidized bed

    Institute of Scientific and Technical Information of China (English)

    Yang Xuliang; Zhao Yuemin; Luo Zhenfu; Chen Zengqiang; Song Shulei

    2011-01-01

    Dry coal beneficiation using an air dense medium fluidized bed (ADMFB) requires the formation of a stable and uniform bed from the dense medium.Others have shown that the structure and geometric parameters of the air distributor have a significant influence on the experimentally observed fluidization quality.In this study we used a sintered metal distributor (SMD) in the ADMFB separator and study its effect on the fluidization quality.The results show that for the same open area ratio (OAR),a smaller aperture in the SMD will provide improved fluidization quality.If aperture size is held constant bigger open area ratios result in improved fluidization quality.And,the fluidization quality also improves when the pressure drop across the SMD increases.A model relating distributor pressure drop and the geometric parameters of the SMD is also proposed.

  10. Agglomeration in a fluidized bed using multiple jet streams

    Energy Technology Data Exchange (ETDEWEB)

    Rehmat, A.; Abbasian, J. (Institute of Gas Technology, Chicago, IL (United States)); Kothari, M.; Hariri, H.; Arastoopour, H. (Illinois Inst. of Tech., Chicago, IL (United States))

    1992-01-01

    Tests were conducted to determine the overall temperature distribution, temperature in the vicinity of the jets, and the rate of agglomeration in a fluidized bed containing multiple jet streams. Agglomeration of ash during coal gasification increases carbon utilization efficiency considerably. The agglomeration requires a fluidized-bed reactor with a specially designed distributor equipped with a jet to yield a hot zone confined within the bed. The rate of agglomeration depends upon the size and the intensity of the zone. This rate, and hence the unit capacity, could be increased by adding multiple jets to the distributor. The purpose of this study was to verify this phenomenon. The temperature distribution inside the agglomerating fluidized-bed reactor with a single jet was studied by Hariri et al. Various parameters were involved in agglomeration phenomena -- bed material, fluidization velocity, bed temperature, jet velocity, jet temperature, bed geometry, and distributor geometry. Controlled agglomerates were produced in the fluidized bed when a sloped gas distributor consisting of a central jet and a porous plate was used. Gas at temperatures above the melting temperature of a bed material was introduced into the jet and gas at temperatures below the softening temperature was introduced into the distributor. The rate of agglomerate formation was significantly influenced by an increase in either jet air or auxiliary (grid) air temperature. The extent of agglomeration also depended strongly upon the volume of the hot zone confined within the isotherms with temperatures higher than the melting point of the bed material.

  11. Agglomeration in a fluidized bed using multiple jet streams

    Energy Technology Data Exchange (ETDEWEB)

    Rehmat, A.; Abbasian, J. [Institute of Gas Technology, Chicago, IL (United States); Kothari, M.; Hariri, H.; Arastoopour, H. [Illinois Inst. of Tech., Chicago, IL (United States)

    1992-12-31

    Tests were conducted to determine the overall temperature distribution, temperature in the vicinity of the jets, and the rate of agglomeration in a fluidized bed containing multiple jet streams. Agglomeration of ash during coal gasification increases carbon utilization efficiency considerably. The agglomeration requires a fluidized-bed reactor with a specially designed distributor equipped with a jet to yield a hot zone confined within the bed. The rate of agglomeration depends upon the size and the intensity of the zone. This rate, and hence the unit capacity, could be increased by adding multiple jets to the distributor. The purpose of this study was to verify this phenomenon. The temperature distribution inside the agglomerating fluidized-bed reactor with a single jet was studied by Hariri et al. Various parameters were involved in agglomeration phenomena -- bed material, fluidization velocity, bed temperature, jet velocity, jet temperature, bed geometry, and distributor geometry. Controlled agglomerates were produced in the fluidized bed when a sloped gas distributor consisting of a central jet and a porous plate was used. Gas at temperatures above the melting temperature of a bed material was introduced into the jet and gas at temperatures below the softening temperature was introduced into the distributor. The rate of agglomerate formation was significantly influenced by an increase in either jet air or auxiliary (grid) air temperature. The extent of agglomeration also depended strongly upon the volume of the hot zone confined within the isotherms with temperatures higher than the melting point of the bed material.

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

    Science.gov (United States)

    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.

  13. Flow Pattern in a Fluidized Bed with a Non-fluidized Zone

    DEFF Research Database (Denmark)

    Lin, Weigang; Dam-Johansen, Kim; Van den Bleek, Cor. M.

    1997-01-01

    The flow pattern of a fluidized bed with non-fluidized zones is investigated both experimentally and theoretically. Experiments were carried out in such a way that air was introduced only through part of the distributor. The results show a significant amount of air flowing to the zone where no air...... is introduced. However, once the gas velocity exceeds the minimum fluidization velocity in the zone where the air is introduced, the cross-flow hardly changes upon further increase of the gas velocity. A continuity equation and Ergun's equation are used to describe the flow pattern and pressure distribution...... over the bed. Very good agreement between the experimental and calculated results is achieved without any fitting parameter. The results are relevant to the understanding of heat transfer behaviour of a fluidized bed combustor (FBC) that is only partly fluidized to control its load....

  14. Numerical simulation of gas-solid flow in an interconnected fluidized bed

    Directory of Open Access Journals (Sweden)

    Canneto Giuseppe

    2015-01-01

    Full Text Available The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed.

  15. Limestone fragmentation and attrition during fluidized bed oxyfiring

    Energy Technology Data Exchange (ETDEWEB)

    Fabrizio Scala; Piero Salatino [Istituto di Ricerche sulla Combustione - CNR, Napoli (Italy)

    2010-04-15

    Attrition/fragmentation of limestone under simulated fluidized bed oxyfiring conditions was investigated by means of an experimental protocol that had been previously developed for characterization of attrition/fragmentation of sorbents in air-blown atmospheric fluidized bed combustors. The protocol was based on the use of different and mutually complementary techniques. The extent and pattern of attrition by surface wear in the dense phase of a fluidized bed were assessed in experiments carried out with a bench scale fluidized bed combustor under simulated oxyfiring conditions. Sorbent samples generated during simulated oxyfiring tests were further characterized from the standpoint of fragmentation upon high velocity impact by means of a purposely designed particle impactor. Results showed that under calcination-hindered conditions attrition and fragmentation patterns are much different from those occurring under air-blown atmospheric combustion conditions. Noteworthy, attrition/fragmentation enhanced particle sulfation by continuously regenerating the exposed particle surface. 13 refs., 8 figs.

  16. The impact of bed temperature on heat transfer characteristic between fluidized bed and vertical rifled tubes

    Science.gov (United States)

    Blaszczuk, Artur; Nowak, Wojciech

    2016-10-01

    In the present work, the heat transfer study focuses on assessment of the impact of bed temperature on the local heat transfer characteristic between a fluidized bed and vertical rifled tubes (38mm-O.D.) in a commercial circulating fluidized bed (CFB) boiler. Heat transfer behavior in a 1296t/h supercritical CFB furnace has been analyzed for Geldart B particle with Sauter mean diameter of 0.219 and 0.246mm. The heat transfer experiments were conducted for the active heat transfer surface in the form of membrane tube with a longitudinal fin at the tube crest under the normal operating conditions of CFB boiler. A heat transfer analysis of CFB boiler with detailed consideration of the bed-to-wall heat transfer coefficient and the contribution of heat transfer mechanisms inside furnace chamber were investigated using mechanistic heat transfer model based on cluster renewal approach. The predicted values of heat transfer coefficient are compared with empirical correlation for CFB units in large-scale.

  17. Fluidized Bed Air-to-Air Heat Pump Evaporator Evaluation.

    Science.gov (United States)

    1983-07-01

    Frost formation of air-to-air heat pump evaporator surfaces reduces unit efficiency and restricts application. The use of a fluidized bed heat...exchanger as an air-to- heat pump evaporator was investigated to determine if frost accumulation could be eliminated. Experimental investigations were...evaluated, with no practical solution being developed. The use of a fluidized bed heat exchanger for air-to-air heat pump evaporators was determined not feasible. (Author)

  18. Chebyshev super spectral viscosity method for a fluidized bed model

    CERN Document Server

    Sarra, S A

    2003-01-01

    A Chebyshev super spectral viscosity method and operator splitting are used to solve a hyperbolic system of conservation laws with a source term modeling a fluidized bed. The fluidized bed displays a slugging behavior which corresponds to shocks in the solution. A modified Gegenbauer postprocessing procedure is used to obtain a solution which is free of oscillations caused by the Gibbs-Wilbraham phenomenon in the spectral viscosity solution. Conservation is maintained by working with unphysical negative particle concentrations.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingwen [URS Corporation; Morgantown, WV (United States); National Energy Technology Lab. (NETL), Morgantown, WV (United States); Benyahia, Sofiane [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    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. FLUIDIZATION OF FINE POWDERS IN FLUIDIZED BEDS WITH AN UPWARD OR A DOWNWARD AIR JET

    Institute of Scientific and Technical Information of China (English)

    Ruoyu Hong; Jianmin Ding; Hongzhong Li

    2005-01-01

    The hydrodynamic behavior of fine powders in jet-fluidized beds was studied numerically and experimentally. The starting point of numerical simulation was the generalized Navier-Stokes (N-S) equations for the gas and solids phases. The κ-εturbulence model was used for high-speed gas jets in fluidized beds. Computation shows that a suitable turbulence model is necessary to obtain agreement between the simulation and literature experimental data for a high-speed gas jet. The model was applied to simulating the fluidization of fine powders in fluidized beds with an upward or a downward air jet. An empirical cohesion model was obtained by correlating the cohesive force between fine particles using a cohetester. The cohesion model was embedded into the two-fluid model to simulate the fluidization of fine powders in two-dimensional (2-D) beds. To study the fluidization behavior of fine and cohesive powders with a downward jet,experiments were performed in a 2-D bed. Agreement between the computed time-averaged porosity and measured data was obtained. With an upward jet in the bed center, the measured and computed porosities show a dilute central core, especially at very high jet velocities. Based on our experiments and computations, a downward jet located inside the bed is recommended to achieve better mixing and contacting of gas and solids.

  1. Performance of a bench-scale fast fluidized bed carbonator

    DEFF Research Database (Denmark)

    Pathi, Sharat Kumar; Lin, Weigang; Illerup, Jytte Boll

    2014-01-01

    The carbonate looping process is a promising technology for CO2 capture from flue gas. In this process, the CO2 capture efficiency depends on the performance of a carbonator that may be operated as a circulating fluidized bed (CFB). In this paper, the carbonator performance is investigated...... by applying a new experimental method with accurate control of the particle recirculation rate. The experimental results show that the inlet calcium to carbon molar ratio is the main factor on the CO2 capture efficiency in the carbonator, that is, increasing the inlet Ca/C from 4 to 13 results in increasing...... the CO2 capture efficiency from 40 to 85% with limestone having a maximum CO2 capture capacity of only 11.5%. Furthermore, a reactor model for a carbonator is developed based on the Kunii-Levenspiels model. A key parameter in the model is the particle distribution along the height of the reactor, which...

  2. The Study of Gas-Dynamic Processes in the Current Boiler Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Baturin Dmitry A.

    2015-01-01

    Full Text Available The paper presents a numerical simulation of the furnace with a circulating fluidized bed. Numerical study carried out for the bottom of the combustion chamber with the varying heights of volume filling. The results of the concentration of particulate matter and fields of speeding, as well as a graphical representation of changes in the concentration of particles on the bed height. Simulation performed in Euler - Euler representation on a 2D model.

  3. Staged fluidized-bed combustion and filter system

    Science.gov (United States)

    Mei, Joseph S.; Halow, John S.

    1994-01-01

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

  4. Combustion en lit fluidisé Fluidized-Bed Combustion

    Directory of Open Access Journals (Sweden)

    Chrysostome G.

    2006-11-01

    Full Text Available Après quelques rappels généraux sur la fluidisation où seront présentés en par-ticulier les avantages qu'elle offre en combustion, on exposera l'état actuel du développement des générateurs à lit fluidisé opérant avec les combustibles suivants : charbon, combustibles pétroliers, résidus divers ; il sera fait mention de la contribution de l'Institut Français du Pétrole (IFP dans les deux derniers domaines.On présentera ensuite les installations les plus récentes en traitement de minerais (grillage des sulfures, calcination de calcaires. En raison de son importance on examinera encore les possibilités de désulfuration au sein de lits fluidisés, de même que seront commentés les travaux de régénération des absorbants.On terminera enfin en mentionnant les développements des lits circulants ou rapides, considérés comme les réacteurs de la seconde génération. After a general review of fluidization including in particular the advantages it offers for combustion, this article describes the present state of the development of fluidized-bed gcnerators operating with the following fuels : cool, petroleum fuels, different residues. Mention is made of Institut Français du Pétrole (IFP contribution in the last two fields. Then the most recent ore-treating installations are described (roasting of sulfides, calcination of limestones. Because of its importance, the possibilities of desulfurizoticn inside fluidized beds is examined, and research on the regeneration of absorbants is commented on. The article ends by mentioning the development of circulating or fast beds which are considered as second generation reactors.

  5. Heat Transfer Characteristic in Oxy-fuel Circulating Fluidized Bed Boiler%富氧燃烧循环流化床锅炉炉内传热特性

    Institute of Scientific and Technical Information of China (English)

    王春波; 侯伟军; 陈传敏; 霍志红

    2011-01-01

    针对富氧燃烧循环流化床锅炉(circulating fluidized bed boiler,CFBB)炉内传热特性进行了研究。考虑气体辐射对传热系数的影响,建立了CFBB富氧燃烧下的传热模型。以一台440t/h循环流化床锅炉为例,通过模型分析了炉内传热情况,并和空气燃烧模式下的传热特性进行比较。进行了氧气浓度在30%、50%、70%气氛下的CFBB炉膛概念性设计。在循环流化床锅炉炉内传热中,灰占主导作用,烟气成分变化对传热系数影响不大。氧气浓度越高,越有必要设置外置换热器来维持炉膛正常运行。%The heat transfer in oxy-fuel circulating fluidized bed boiler (CFBB) was investigated. A model which considers the influence of gases radiation on heat transfer coefficient was set. Take a 440t/h CFBB for example, the heat transfer in furnace was calculated and the results were compared with air-fired CFBB. The model shows the heat transfer coefficient is not be changed greatly in oxy-fuel combustion, because the heat transfer is dominated by the effect of particles, not depend on gases composition. The concept design of oxy-fuel CFBB was done at 30%, 50%, and 70% O2 concentration. It was found the higher concentration of oxygen the more necessary to set an external heat exchanger to keep a normal operation of the furnace.

  6. Autoclaved condition system optimization for the circulating fluidized bed fly ash concrete block%蒸压流化床粉煤灰混凝土砌块养护优化设计

    Institute of Scientific and Technical Information of China (English)

    徐正坦; 翁仁贵

    2012-01-01

    With X-ray fluorescence spectrometry and X-ray diffraction, the chemical compositions of circulating fluidized bed fly ash are analyzed. We work out the prescription for producing the circulating fluidized bed fly ash concrete block, and study the influences of the autoclaved conditions for the compressive strength of concrete block with the orthogonal design method. The results show that the key factors of the caring system are as following in order: heating time, constant temperature time, temperature decreasing time and constant pressure. The best autoclaved conditions are heating time 3 hours, constant temperature time 6 hours, constant pressure 1 MPa, temperature decreasing time 1.5 hours.%利用X射线荧光光谱仪、XRD等检测手段对循环流化床粉煤灰进行化学成分定性和定量分析。通过选用确定组分的基础蒸压循环流化床粉煤灰混凝土砌块配方,并用正交设计实验方法安排和组织试验,研究了养护制度对蒸压循环流化床粉煤灰混凝土砌块抗压强度等性能的影响。实验结果表明,在蒸压养护制度中,影响循环流化床粉煤灰混凝土试块抗压强度的主要因素为升温时间,因素的主次顺序为:升温时间〉恒温时间〉降温时间〉恒温压力。其最佳的蒸压养护制度:升温时间3h,恒温时间6h,恒温压力1MPa,降温时间1.5h。

  7. Modeling on the Combustion System of Large-Scale Circulating Fluidized Bed Boiler%大型循环流化床锅炉燃烧系统数学模拟

    Institute of Scientific and Technical Information of China (English)

    徐志; 王勤辉; 骆仲泱; 倪明江

    2011-01-01

    数学模型是研究和发展大型循环流化床锅炉的重要方法.在浙江大学提出的适用于中小型循环流化床锅炉的整体数学模型的基础上,建立了适用于大型循环流化床锅炉的数学模型.模型采用了基于环-核结构的流体动力学模型,并考虑了宽筛分燃料颗粒所经历的破碎、燃烧等过程.模拟了国内一台300MWe循环流化床锅炉,模拟计算结果与锅炉的运行测量值基本吻合.%Mathematical model is an important method in the study and the development of large-scale circulating fluidized bed (CFB) boiler. On the basis of the overall mathematical model for the medium and small scale CFB boiler, a mathematical model for large-scale CFB boiler is developed. In the modeling, the CFB riser is divided in two regions: the bottom zone in turbulent fluidization regime and the upper zone with core-annulus solids flow structure. The model takes into account the fragmentation and combustion process of the widely sized particles. The model results are in good agreement with the operational data of a 300 MWe CFB boiler.

  8. Temperature distribution and control in liquefied petroleum gas fluidized beds

    Institute of Scientific and Technical Information of China (English)

    Li Wang; Ping Wu; Yanping Zhang; Jing Yang; Lige Tong

    2004-01-01

    Temperature distribution and control have been investigated in a liquefied petroleum gas (LPG) fluidized bed with hollow corundum spheres (A12O3) of 0.867-1.212 mm in diameter at moderately high temperatures (800-1100℃). Experiments were carried out for the air consumption coefficient α in the range of 0.3 to 1.0 and the fluidization number N in the range of 1.3 to 3.0. Particle properties, initial bed height, α and N all affect temperature distribution in the bed. Bed temperature can be adjusted about 200℃ by combined the adjusting of α and N.

  9. Combustion in fluidized bed reactors; Verbrennung in Wirbelschichtreaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Thome-Kozmiensky, Karl J. [vivis CONSULT GmbH, Nietwerder (Germany)

    2013-03-01

    Since the first application for the coal gasification, the fluidized bed technology has passed an impressive development. Nowadays, the fluidized bed technology is utilized at chemical processes, drying and cooling, gasification, combustion and purification of exhaust gas. In the firing technology, the fluidized technology initially has been proved in the combustion of very high ash coal and sewage sludge. Recently, the fluidized bed technology also is applied in the drying of sewage sludge, combustion of domestic waste - as in Japan and Sweden - as well as in the gasification and combustion of substitute fuels, biomass - wood pellets, wood chips, straw, cocoa shells and so forth - and residues from the paper manufacturing - such as in Germany and Austria. Under this aspect, the author of the contribution under consideration reports on the combustion of sewage sludge, substitute fuels and biomass.

  10. Fluidized bed gasification of industrial solid recovered fuels.

    Science.gov (United States)

    Arena, Umberto; Di Gregorio, Fabrizio

    2016-04-01

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

  11. Fluidized bed combustion of pesticide-manufacture liquid wastes

    Directory of Open Access Journals (Sweden)

    SAŠA MILETIĆ

    2010-04-01

    Full Text Available Industrial liquid wastes can be in the form of solutions, suspensions, sludges, scums or waste oil and have organic properties. The objective of this work was to demonstrate the technical feasibility of a fluidized bed as a clean technology for burning liquid waste from a pesticide production plant. The combustion of liquid waste mixtures, obtained from realistic samples, was investigated in a pilot scale fluidized bed with quartz sand particles of 0.63–1.25 mm in diameter and 2610 kg/m3 in density at 800–950 °C. To ensure complete combustion of liquid waste and additional fuel, the combustion chamber was supplied with excess air and the U/UmF (at ambient temperature was in between 1.1 and 2.3. In the fluidized bed chamber, liquid waste, additional liquid fuel and air can be brought into intense contact sufficient to permit combustion in bed without backfire problems. The experimental results show that the fluidized bed furnace offers excellent thermal uniformity and temperature control. The results of the combustion tests showed that degradation of liquid wastes can be successfully realized in a fluidized bed with no harmful gaseous emissions by ensuring that the temperatures of both the bed and the freeboard are not lower than 900 °C.

  12. Fluidized-bed pyrolysis of waste bamboo

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Bamboo was a popular material substituting for wood, especially for one-off commodity in China. In order to recover energy and materials from waste bamboo, the basic characteristics of bamboo pyrolysis were studied by a thermogravimetric analyzer. It implied that the reaction began at 190~210 ℃, and the percentage of solid product deceased from about 25% to 17% when temperature ranged from 400 ℃ to 700 ℃. A lab-scale fluidized-bed furnace was setup to research the detailed properties of gaseous, liquid and solid products respectively. When temperature increased from 400 ℃ to 700 ℃, the mass percent of solid product decreased from 27% to 17% approximately, while that of syngas rose up from 19% to 35%. When temperature was about 500℃, the percentage of tar reached the top, about 31%. The mass balance of these experiments was about 93%~95%. It indicated that three reactions involved in the process: pyrolysis of exterior bamboo, pyrolysis of interior bamboo and secondary pyrolysis of heavy tar.

  13. CFD simulation of a gas-solid fluidized bed with two vertical jets

    Institute of Scientific and Technical Information of China (English)

    Pei Pei; Kai Zhang; Jintian Ren; Dongsheng Wen; Guiying Wu

    2010-01-01

    A computational fluid dynamics(CFD)model is used to investigate the hydrodynamics of a gas-solid fluidized bed with two vertical jets.Sand particles with a density of 2660 kg/m3 and a diameter of5.0 × 10-4 m are employed as the solid phase.Numerical computation is carried out in a 0.57 m × 1.00 m two-dimensional bed using a commercial CFD code.CFX 4.4,together with user-defined Fortran subrou-tines.The applicability of the CFD model is validated by predicting the bed pressure drop in a bubbling fluidized bed,and the jet detachment time and equivalent bubble diameter in a fluidized bed with a single jet.Subsequently,the model is used to explore the hydrodynamics of two vertical jets in a fluidized bed.The computational results reveal three flow patterns,isolated,merged and transitional jets,depending on the nozzle separation distance and jet gas velocity and influencing significantly the solid circulation pattern.The jet penetration depth is found to increase with increasing jet gas velocity,and can be predicted reasonably well by the correlations of Hang et al.(2003)for isolated jets and of Yang and Keairns(1979)for interacting jets.

  14. Effect of biomass-sulfur interaction on ash composition and agglomeration for the co-combustion of high-sulfur lignite coals and olive cake in a circulating fluidized bed combustor.

    Science.gov (United States)

    Varol, Murat; Atimtay, Aysel T

    2015-12-01

    This study aimed to investigate the effect of biomass-sulfur interaction on ash composition and agglomeration for the co-combustion of high-sulfur lignite coals and olive cake in a circulating fluidized bed combustor. The tests included co-combustion of 50-50% by wt. mixtures of Bursa-Orhaneli lignite+olive cake and Denizli-Kale lignite+olive cake, with and without limestone addition. Ash samples were subjected to XRF, XRD and SEM/EDS analyses. While MgO was high in the bottom ash for Bursa-Orhaneli lignite and olive cake mixture, Al2O3 was high for Denizli-Kale lignite and olive cake mixture. Due to high Al2O3 content, Muscovite was the dominant phase in the bottom ash of Denizli Kale. CaO in the bottom ash has increased for both fuel mixtures due to limestone addition. K was in Arcanite phase in the co-combustion test of Bursa/Orhaneli lignite and olive cake, however, it mostly appeared in Potassium Calcium Sulfate phase with limestone addition.

  15. 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.

    Science.gov (United States)

    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.

  16. 25 t/h循环双流化床锅炉在节能改造中的应用与探讨%Application and Discussion of 25t/h Circulating Double Fluidized Bed Boiler in Energy Saving Reform

    Institute of Scientific and Technical Information of China (English)

    朱征宇

    2013-01-01

    从技术特点、生产运行情况、经济效益、改进完善等多方面对循环双流化床锅炉在节能改造中的运用进行分析,总结该锅炉节能改造中存在的利弊,促进该炉型的不断改进和完善,并结合设计规范与设计理念,对今后锅炉的结构与节能措施提出设想和建议,促进该炉型更好的推广应用。%This paper makes analysis on the application of circulating double fluidized bed boiler in the energy saving from the technical characteristics, production operation , economic benefits, use improving and other aspects of the analysis and concludes the existing advantages and disadvantages in energy saving reform of boiler. It promotes the continuous improvement of the boiler type. Combining with the design concept and design specification, this paper proposes suggestions for measures of energy saving and the future structure of the boiler, which promotes the popularization and application of this type boiler.

  17. 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

    Institute of Scientific and Technical Information of China (English)

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

    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 × 10-3 m/sec and superficial liquid velocity 8.65 × 10-3 m/sec.

  18. Ash and heavy metals in fluidized bed-combustion; Tuhka ja raskasmetallit puuperaeisen jaetteen kerrosleijupoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Kaessi, T.; Aittoniemi, P. [IVO International, Vantaa (Finland)

    1996-12-01

    Combustion ashes and submicron fly ash particles were characterized in two industrial boilers (bubbling vs. circulating fluidized bed) burning paper mill deinking sludge and bark or wood as support fuel. Bulk samples from fly ash, circulating ash and bottom ash were analyzed. Fine particles in fly ash were monitored and sampled for microscopic studies. The mass size distribution of fly ash was measured and the chemical composition according to particle size was analyzed. The results showed that ash consists of large and friable clusters formed by sintering of small mineral particles originating from paper fillers. Very few ash particles were fused and they were found only among the smallest particles. No agglomerates of fused particles were found. If the residence time in furnace is long enough sintering may proceed further and ash structure grows more dense. No indication of ash vaporization was detected. These results were similar for bubbling and circulating fluidized bed boilers. (author)

  19. DRYING OF GRANULAR MATERIALS IN AGITATED FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An experimental study of the drying characteristics of an agitated fluidized bed dryer is presented and discussed. In the study, the citric acid particles were used as bed material with the diameters ranging from 0.2mm to 1.3mm. The variables affecting apparently the drying rate were found to be the mass flow rate, the inlet air temperature, the rotary speed of agitating mechanism and the particles feed rate. Comparing with other variables considered, mass flow rate was found to have the least important influence on the drying rate. The agitated fluidized bed dryer is suitable to drying agglomerating or sticky materials.

  20. Bed dynamics of gas-solid fluidized bed with rod promoter

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The dynamic characteristics of a gas-solid fluidized bed with different rod promoters have been investigated in terms of bed expansion and fluctuation, minimum fluidization velocity and distributor-to-bed pressure drop ratio at minimum fluidization velocity. Experimentation based on statistical design has been carried out and model equations using factorial design of experiments have been developed for the above mentioned quantities for a promoted gas-solid fluidized bed. The model equations have been tested with additional experimental data. The system variables include four types of rod promoters of varying blockage volume, bed particles of four sizes and four initial static bed heights. A comparison between the predicted values of the output variables using the proposed model equation with their corresponding experimental ones shows fairly good agreement.

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

    Science.gov (United States)

    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.

  2. Particle size distribution of ashes and the behaviour of metals when firing Salix in a circulating fluidized bed boiler (CFB); Askans partikelfraktionsfoerdelning och metallernas beteende vid eldning av Salix i en CFB-panna

    Energy Technology Data Exchange (ETDEWEB)

    Sfiris, G.; Johansson, A. [Vattenfall Utveckling AB, Stockholm (Sweden); Valmari, T.; Kauppinen, E.; Pyykoenen, J.; Lyyraenen, J. [VTT Technical Research Centre of Finland, Espoo (Finland)

    1999-07-01

    This project is part of the Ash Recovery Programme aimed at establishing the environmental, technical and financial preconditions for returning wood ash to the forest. The programme is funded jointly by NUTEK, Sydkraft and Vattenfall. This report summarises the results of the experimental and modelling work to study the behaviour of the metals (especially Cd and K), after burning Salix in a 3-12 MW Circulating Fluidized Bed (CFB) boiler. The purpose of the study was to determine, using the experimental data, where cadmium and potassium condense, on what size particles they condense, and the decisive parameters governing these processes. Measurements of the fly ash particle size distribution carried out with a Berner Low Pressure Impactor (BLPI), coupled to a pre-cyclone. Samples were collected from three points: in the convection path at 650 deg C, after the convection path but before the secondary cyclone (160 deg C), and after the bag house (150 deg C). Wet chemical sampling was made for Cd, K, Zn and Pb, with three types of sampling equipment: collection of both particles and gas, collection of particles only, and analysis of the gas phase only. Analysis was made of samples from two places in the convection path (650 deg C and 250 deg C). Samples of bed material, bottom ash and fly ash have been subjected to scanning electron microscopy (SEM), and in addition a few fly ash particles, sampled after the convection path, were subjected to energy dispersive X-ray analysis (EDX). Based on experimental results, modelling work was carried out with an equilibrium model and with a general aerosol computer model ABC (Aerosol Behaviour in Combustion)

  3. FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C

    2006-12-22

    Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO{sub 2} and steam, and nitrate/nitrite components, if any, to N{sub 2}. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO{sub 4}, I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the <2g/m{sup 2} durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form.

  4. Erosion of heat exchanger tubes in fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E.K.; Flemmer, R.L.C.

    1991-01-01

    This final report describes the activities of the 3-year project entitled Erosion of Heat Exchanger Tubes In Fluidized Beds.'' which was completed at the end of 1990. Project accomplishments include the collection of a substantial body of wear data In a 24in. [times] 24in. fluidized bed, comparative wear results In a 6in. [times] 6in. fluidized bed, the development of a dragometer and the collection of a comprehensive set of drag force data in the 24in. [times] 24in. bed, Fast Fourier Transform (FFT) analysis of bubble probe data to establish dominant bubble frequencies in the 24in. [times] 24in. bed, the use of a heat flux gauge for measurement of heat transfer coefficients in the 24in. [times] 24in. bed and the modeling of the tube wear in the 24in. [times] 24in. bed. Analysis of the wear data from the 24in. square bed indicates that tube wear increases with increase in superficial velocity, and with increase in tube height. The latter effect is a result of the tubes higher up in the bed seeing greater movement of dense phase than tubes lower down In the bed. In addition, tube wear was found to decrease with increase in particle size, for constant superficial velocity. Three models of tube wear were formulated and provided acceptable prediction of wear when compared with the experimental data.

  5. Confined fluidization of fines in fixed bed of coarse particles

    Directory of Open Access Journals (Sweden)

    Buczek Bronisław

    2016-12-01

    Full Text Available Experiments on a confined fluidized bed system with various shapes of particles have been presented in the paper. Its influence on hydrodynamic properties in the whole range of gas velocity has been analysed. Relations allowing calculation of the Richardson-Zaki-type equation coefficients, including description of inter-particle void and gas pressure drop in such systems have been determined. Necessary condition for confined fluidization of non-spherical coarse particles has also been determined.

  6. Computational fluid dynamic modeling of fluidized-bed polymerization reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rokkam, Ram [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.

  7. Direct reduction of hematite powders in a fluidized bed reactor

    Institute of Scientific and Technical Information of China (English)

    Qingshan Zhu; Rongfang Wu; Hongzhong Li

    2013-01-01

    Ultrafine hematite powder was reduced to produce ultrafine iron powder in a 50%Ar-50%H2 atmosphere at 450-550 ℃ in a fluidized bed reactor.The ultrafine hematite powder shows the typical agglomerating fluidization behavior with large agglomerates fluidized at the bottom of the bed and small agglomerates fluidized at the upper part of the bed.It was found that defluidization occurred even at the low temperature of 450 ℃ with low metallization rate.Defluidization was attributed mainly to the sintering of the newly formed iron particles.Granuation was employed to improve the fluidization quality and to tackle the defluidization problem,where granules fluidized like a Geldart's group A powder.Granulation was found to effectively reduce defluidization during reduction,without however sacrificing reduction speed.The asreduced iron powders from both the ultrafine and the granulated hematite exhibited excellent sintering activity,that is,fast sintering at temperature of as low as ~580 ℃,which is much superior as compared to that of nano/ultrafine iron powders made by other processes,

  8. Numerical Study of Pyrolysis of Biomass in Fluidized Beds

    Science.gov (United States)

    Bellan, Josette; Lathouwers, Danny

    2003-01-01

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

  9. Metallic species derived from fluidized bed coal combustion. [59 references

    Energy Technology Data Exchange (ETDEWEB)

    Natusch, D.F.S.; Taylor, D.R.

    1980-01-01

    Samples of fly ash generated by the combustion of Montana Rosebud coal in an experimental 18 inch fluidized bed combustor were collected. The use of a heated cascade impactor permitted collection of size fractionated material that avoided condensation of volatile gases on the particles. Elemental concentration trends were determined as a function of size and temperature and the results compared to published reports for conventional power plants. The behavior of trace metals appears to be substantially different in the two systems due to lower operating temperatures and the addition of limestone to the fluidized bed. Corrosion of the impactor plates was observed at the highest temperature and lowest limestone feed rate sampled during the study. Data from the elemental concentration and leaching studies suggest that corrosion is most likely due to reactions involving sodium sulfate. However, it is concluded that corrosion is less of a potential problem in fluidized-bed systems than in conventional coal-fired systems.

  10. ELECTROSTATIC PHENOMENA IN GAS-SOLIDS FLUIDIZED BEDS

    Institute of Scientific and Technical Information of China (English)

    Hsiaotao T. Bi

    2005-01-01

    Electrostatic charges are generated by particle-wall, particle-particle and particle-gas contacts in gas-solids transport lines and fluidized bed reactors. High particle charge densities can lead to particle agglomeration,particle segregation, fouling of reactor walls and internals, leading to undesirable by-product and premature shut-down of processing equipment. In this paper, the charge generation, dissipation and segregation mechanisms are examined based on literature data and recent experimental findings in our laboratory. The particle-wall contact charging is found to be the dominant charge generation mechanism for gas-solids pneumatic transport lines, while bipolar charging due to intimate particle-particle contact is believed to be the dominant charge generation mechanism in gas fluidized beds. Such a bipolar charging mechanism is also supported by the segregation patterns of charged particles in fluidized beds in which highly charged particles tend to concentrate in the bubble wake and drift region behind rising bubbles.

  11. Pressurized fluidized-bed combustion technology exchange workshop

    Energy Technology Data Exchange (ETDEWEB)

    ,

    1980-04-01

    The pressurized fluidized-bed combustion technology exchange workshop was held June 5 and 6, 1979, at The Meadowlands Hilton Hotel, Secaucus, New Jersey. Eleven papers have been entered individually into EDB and ERA. The papers include reviews of the US DOE and EPRI programs in this area and papers by Swedish, West German, British and American organizations. The British papers concern the joint program of the USA, UK and FRG at Leatherhead. The key factor in several papers is the use of fluidized bed combustors, gas turbines, and steam turbines in combined-cycle power plants. One paper examines several combined-cycle alternatives. (LTN)

  12. Atmospheric fluidized bed coal combustion research, development and application

    CERN Document Server

    Valk, M

    1994-01-01

    The use of fluidized bed coal combustion technology has been developed in the past decade in The Netherlands with a view to expanding the industrial use of coal as an energy supply. Various research groups from universities, institutes for applied science and from boiler industries participated and contributed to this research area. Comprehensive results of such recent experimentation and development work on atmospheric fluidized bed combustion of coal are covered in this volume. Each chapter, written by an expert, treats one specific subject and gives both the theoretical background as well a

  13. Development of a fluidized bed system for adsorption of phenol from aqueous solutions with commercial macroporous resins

    Directory of Open Access Journals (Sweden)

    R. A. Corrêa

    2007-03-01

    Full Text Available This work is related to removal of phenol from wastewaters by adsorption onto polymeric resins, a current alternative to activated carbon. A closed circuit, bench-scale liquid fluidized bed system was developed for this purpose. Phenol aqueous solutions with initial concentrations in the range of 0.084 to 0.451 kg/m³ were used to fluidize small permeable capsules of stainless steel screen containing a commercial resin at 308 K. Experiments were carried out using a fluidizing velocity 20% above that of the minimum fluidization of the capsules. Typically, 30 passages of the liquid volume circulating through the bed were required to reach a quasi-equilibrium concentration of phenol in the treated effluent. A simple batch adsorption model using the Freundlich isotherm successfully predicted final phenol concentrations. Suspended solids, often present in residual waters and a common cause of fixed bed clogging, were simulated with wood sawdust.

  14. Reforming Analysis of Environmental Protection Technologies in Circulating Fluidized Bed Boiler%环保新标准的循环流化床锅炉改造分析

    Institute of Scientific and Technical Information of China (English)

    马双忱; 张华仙; 朱思洁; 雷雨; 杨静

    2015-01-01

    对循环流化床在脱硝、脱硫和除尘等方面环保技术路线进行了分析,权衡各项技术的利弊及经济因素,结合新颁布的火电厂大气污染物排放标准(GB 13223—2011),做出如下建议:半干旋转喷雾法脱硫工艺( SDA)和SCR结合使用后,氮氧化物的脱除效率可达到95%,循环流化床中高灰分的环境不适合使用SCR, SNCR的脱除效率虽然相对较低,但是通过调整还原剂的停留时间和与烟气的混合程度,脱硝效率可达70%以上,完全可以满足新环保标准的要求;石灰石-石膏湿法脱硫技术成熟,脱硫效率高,负荷适应性好,在循环流化床炉内脱硫的基础上外加该工艺,可以保证足够的脱硫效率;电袋组合式除尘器发挥了两种除尘器的技术优势,可以达到新标准的要求。%In this essay, three environmental protection technical routes, denitrification, desulfurization and dust removal of CFB boilers, were analyzed.Considering the advantages and disadvantages of the techniques, economic factors, and with the purpose of meeting the newly issued Power Plant Air Pollutants Emission Standard (GB13223-2011), this essay suggests the following.The combination of SCR and SDA can increase the NOx removal efficien-cy to 95%.But it does not apply to the environment of high ash content in the circulating fluidized bed.Despite of the low efficiency of the SNCR, denitrification efficiency can be up to 70% with the adjustment of the residence time and the mixing proportion of the flue gas, which can fully meet the new environmental standards.In addition, the limestone-gypsum wet FGD technology, with a high desulfurization efficiency and good load adaptation, is com-paratively mature.If the process is added after circulating fluidized bed desulfurization, adequate removal efficiency can be ensured.The advantages of two kinds of dust remover being considered, the electrostatic bag dust remover

  15. Coal. Fluidized bed, a world record; Charbon. Lit fluidise: record mondial

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    In April 1996, the `Societe Provencale du Lit Fluidise`, a subsidiary of Electricite de France (EDF) has put into service in Gardanne, the most powerful circulating fluidized bed boiler in the world, producing 600 MWt; it was constructed by GEC Alsthom Stein Industrie, and will strongly reduce the SO{sub 2} emissions from the coal power plant of Gardanne, which use a highly sulfurous coal. New regulations concerning the French coal industry are also introduced

  16. Minimum slugging velocity in fluidized beds containing vertical rods

    Energy Technology Data Exchange (ETDEWEB)

    Coronella, C.J.; Lee, S.Y.; Seader, J.D. (University of Utah, Salt Lake City, UT (United States). Dept. of Chemical Engineering)

    1994-09-01

    A new method for determining the onset of slugging in fluidized beds is presented. Pressure-drop fluctuations, measured from below the distributor to the gas exit line, are transformed to the frequency domain by the power spectral desity function (PSDF). The dominant frequency of the PSDF corresponds to the eruption frequency of bubbles or slugs. A fluidized bed is in the slugging regime when this dominant frequency, f[sub d], remains constant with changing gas velocity. This method is an improvement over previous methods because of the simple nature of the apparatus required, and because it is possible to locate the pressure probes so that they do not interfere with the fluidization or undergo rapid wear from the constant particle movement. This method was used to determine the gas velocity corresponding to the transition from the bubbling to the slugging regime for a 10cm diameter bed of sand fluidized with air and containing three 1.9cm diameter vertical rods at 5.2cm centre-to-centre triangular spacing and extending the length of the bed, and to compare the results with those from the same bed without any internal rods. The presence of the vertical rods inhibited the onset of the slugging regime, and significantly extended the bubbling regime to higher gas velocities. 32 refs., 12 figs.

  17. Biofilm detachment mechanisms in a liquid-fluidized bed.

    Science.gov (United States)

    Chang, H T; Rittmann, B E; Amar, D; Heim, R; Ehlinger, O; Lesty, Y

    1991-08-20

    Bed fluidization offers the possibility of gaining the advantages of fixed-film biological processes without the disadvantage of pore clogging. However, the biofilm detachment rate, due to hydrodynamics and particle-to-particle attrition, is very poorly understood for fluidized-bed biofilm processes. In this work, a two-phase fluidized-bed biofilm was operated under a constant surface loading (0.09 mg total organic carbon/cm(2) day) and with a range of bed height (H), fluid velocities (U), and support-particle concentrations (C(p)). Direct measurements were made for the specific biofilm loss rate coefficient (b(s))and the total biofilm accumulation (X(f)L(f)). A hydrodynamic model allowed independent determination of the biofilm density (X(f)), biofilm thickness (L(f)), liquid shear stress (tau), and Reynolds number (Re). Multiple regression analysis of the results showed that increased particle-to-particle attrition, proportional to C(p) and increased turbulence, described by Re, caused the biofilms to be denser and thinner. The specific detachment rate coefficient (b(s)) increased as C(p) and Re increased. Almost all of the 6, values were larger than predicted by a previous model derived for smooth biofilms on a nonfluidized surface. Therefore, the turbulence and attrition of bed fluidization appear to be dominant detachment mechanisms.

  18. Investigation on Agropellet Combustion in the Fluidized Bed

    Science.gov (United States)

    Isemin, R. L.; Konayahin, V. V.; Kuzmin, S. N.; Zorin, A. T.; Mikhalev, A. V.

    Agricultural wastes (straw, sunflower or millet husk, etc.) are difficult to use as fuel because of low bulk density and relatively big ash content with a low melting point. It is possible to produce agropellets of agricultural wastes which are suggested to combust in a fluidized bed of pellets alone, their char particles and ash. The characteristics of the process of fluidization of agropellets are investigated at room temperature. The experiments on agropellet combustion in a fluidized bed are carried out in an experimental set-up. The results of the experiments have shown that in such a bed the pellets produced of straw and millet husk combust with the same rate as those of wood though the latter contain 8.76 - 19.4 times less ash. The duration of combustion of the same portion of straw pellets in a fluidized bed is 3.74 - 7.01 times less than the duration of combustion of cut straw in a fixed bed. Besides, the movement of agropellets prevents agglomeration and slagging of a boiler furnace.

  19. DESIGN AND APPLICATION OF FLUIDIZED BED PHOTOCATALYTIC REACTOR

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Photocatalytic degradation of organic pollutant is a new and potential method to transform it to harmless inorganic material, such as CO2 and H2O. So far, most of photocatalytic reactors were cylinder or tabulate photoreactor. The relevant photocatalyst was TiO2 nanometer powder. Although a few investigators had aimed their research field to fluidized bed reactor, their reaction systems were of biphase, such as solid-liquid or solid-gas. Few people focused their research on the triphasic fluidized bed photocatalytic reactor[1]. Compared with traditional photoreactors, a triphasic fluidized bed photoreactor has more advantages[2]: (1) The solid photocatalyst can be separated easily. (2) Its configuration meets the requirement of higher surface area-to-volume ratio of photocatalytic, which is much lower in a fixed bed or a plate photoreactor. (3) The UV light can be used more efficiently. (4) The mass transfer conditions can be controlled and improved easily. (5) It suited to pilot-scale or large-scale operations. For the UV light penetration and photon efficiency should be considered, the photocatalytic reactor differed greatly from a typical fluidized bed reactor.

  20. 循环流化床一体化污泥干化焚烧炉热工及排放性能%Thermal Performance and Pollutant Emissions of Circulating Fluidized Bed Sludge Drying/Incineration Integrated System

    Institute of Scientific and Technical Information of China (English)

    吕清刚; 侯海盟; 朱建国; 李诗媛; 包绍麟; 丁艳辉; 李成江; 吴凡松; 朱开东

    2013-01-01

    依据国家环境排放标准,对杭州市七格污水处理厂100 t/d循环流化床一体化污泥焚烧炉进行了热工性能测试和污染物排放测试.热工性能测试结果表明:污泥焚烧炉的燃烧效率>98.5%.烟气污染物排放中各污染物浓度均低于标准限值,其中,二(口恶)英类物质的排放浓度在0.017 ~ 0.03 ngTEQ/m3范围内.焚烧系统产生的灰渣重金属浸出浓度均低于危险废物鉴别标准,可按一般固废利用或处置.%Based on the national environmental emission standards,the thermal performance and pollutant emissions of a 100 t/d circulating fluidized bed sludge drying/incineration integrated system at Qige WWTP in Hangzhou were tested.The combustion efficiency of the sludge incinerator was higher than 98.5 %.The emission concentrations of all the tested flue gas pollutants were lower than the standard limits.The emission concentration of dioxins was between 0.017 and 0.03 ngTEQ/m3.The leaching concentrations of heavy metals in the ashes were much lower than the identification standards for hazardous wastes,and the ashes could be utilized or disposed as common solid wastes.

  1. 循环流化床烟气脱硫模拟中试试验研究%Experimental Research on a Pilot-Scale Circulating Fluidized Bed for Flue Gas Desulfurization

    Institute of Scientific and Technical Information of China (English)

    冯斌; 李大骥; 周志良; 吴颖海; 杨军

    2001-01-01

    在东南大学热能工程研究所建立的φ600mm,处理烟气量达2000m3/h(标准状态,下同)的循环流化床烟气脱硫中试试验台上,进行了循环流化床烟气脱硫的试验研究.分别讨论了Ca与S的摩尔比、烟气流量、入口SO2浓度、反应温度等因素对脱硫效率影响.试验结果表明,Ca与S的摩尔比和反应温度的影响最为显著,烟气量和SO2入口浓度也有一定的影响,但不十分明显,说明循环流化床烟气脱硫工艺对锅炉负荷和燃煤煤种的变化有较好的适应性.%At present, SO2 pollution control of coal combustion is an urgenttask in the field of air pollution control in China. An experimental research was carried on the simulated pilot-scale test facility of Circulating Fluidized Bed for Flue Gas Desulfurization (CFB-FGD) whose diameter is 600mm and nominal flow rate of the flue gas is 2 000 m3/h in Thermal Engineering Research Institute of Southeast University. The Ca/S molar ratio and the reaction temperature have great influence on the efficiency of desulfurization, but the influences of the flow rate and SO2 inlet concentration are not obvious. So the result indicates that CFB-FGD technology is applicable for the variation of the boiler’s load and the coal used.

  2. Preparation of circulating fluidized bed combustion fly ash-based cementitious materials with carbide slag%利用电石渣改性固硫灰制备胶凝材料的研究

    Institute of Scientific and Technical Information of China (English)

    霍琳; 李军; 卢忠远

    2012-01-01

    基于固硫灰自身的火山灰活性和自硬性,提出用钙质激发剂激发固硫灰活性制备固硫灰基胶凝材料.实验研究表明在激发剂的作用下,掺入偏高岭土后胶凝材料强度提高80%以上.用内掺50%偏高岭土的固硫灰,采用电石渣或熟石灰复合水玻璃作为激发剂制备胶凝材料都在体系的碱含量为30%,水玻璃的模数为2.0,养护温度为60℃时强度达到最大,两种激发剂对强度的影响差异不大,而采用电石渣作为激发剂更节约成本,更具优势.%Based on the pozzolanic activity and self-hardening property of circulating fluidized bed combustion (CFBC) fly ash, this paper proposes to prepare CFBC fly ash-based cementitious materials by stimulating the CFBC fly ash with calcium activator. Experimental studies have shown thai the strength of the cementitious materials mixed with metakaolin in the role of the activator increased by more than 80%.The cementitious material prepared with CFBC fly ash and 50% metakaolin and activated by carbide slag or lime mixed with water glass solution can achieve optimal strength on following conditions: alkali content was 30% , modulus of water glass was 2.0, and curing under 60℃,. The two activators had no significant impact on the strength, while taking carbide slag as activator was more sensible than taking lime since it was industrial waste.

  3. The experimental study on new type baking-free brick prepared the circulating fluidized bed boiler (CFBB) ash%循环流化床锅炉灰渣制备新型免烧砖的试验研究

    Institute of Scientific and Technical Information of China (English)

    黄鑫; 夏举佩; 周新涛

    2014-01-01

    本文以循环流化床锅炉(C FBB )灰渣为主要原料,通过实验获得了其制备免烧砖的最佳工艺配料为:石灰7%、飞灰43%、底渣30%、骨料瓜子石20%。通过蒸汽养护和自然养护对比,发现在低石灰掺量时,自然养护效果明显低于蒸汽养护,但随着石灰用量的增加,二者差异逐渐缩小,当高于7%时,检测结果基本一致,在此基础上,通过扩大性工业试验,采用自然养护方式,可生产标号为150的免烧砖砌块。%In this paper ,circulating fluidized bed boiler (CFBB) ash is used as the main raw material for preparing baking free brick to obtain through experiment the optimal ingredients as follows :7% lime ,43%fly ash ,30% bottom ash ,20% aggregate of oval stone .By steam curing and natural curing contrast ,we find that the effect of nature curing is significantly lower than the steam curing .But with the increasing of lime dosage ,the difference is gradually reduced .When lime dosage is higher than 7% ,the test results are basically consistent .On this basis ,unburned block labeled 150 can be produced using natural curing method through the expansion of industrial test .

  4. Experimental Study on Synthesis Molecular Sieve Ashes of Circulating Fluidized Bed%利用循环流化床飞灰合成分子筛实验研究

    Institute of Scientific and Technical Information of China (English)

    姚刚; 卿山; 马林转; 岳争超; 何屏; 李瑛

    2009-01-01

    Experimental study showed when n (SiO2) /n (Al2O3)≈3.3, Na2O/SiO2 was 1.2~1.5, H2O/Na2O was 40~70, the gel temperature was 60 -70 ℃, time continued 2h, reaction temperature was 90 -95 ℃, the crystallization time continued 4 -6 h, the fly ash of circulating fluidized bed boiler could synthesize the molecular sieve of higher crystallinity. It had better characteristic peak of P zeolite by the characterization of XRD, good stability by TGA. The relative degree of crystallization was 53%.%利用循环流化床锅炉粉煤灰在n(SiO2)/n(Al2O3)≈3.3、Na2O/SiO2为1.2~L 5、H2O/Na2O为40~70、凝胶温度和时间分别为60-70℃、时间2 h、晶化反应温度在90-95℃,晶化时间为4-6 h的条件下可以合成出较高结晶度的分子筛,通过XRD表征发现,产品具有良好的P型分子筛特征峰,其相对结晶度为53%.热重分析可知其具有好的稳定性.

  5. Measurements of heat transfer and operating experience at the Wolfsburg power plant with a circulating fluidized bed furnace; Messungen zum Waermeuebergang und Betriebserfahrungen im Kraftwerk Wolfsburg mit zirkulierender Wirbelschichtfeuerung

    Energy Technology Data Exchange (ETDEWEB)

    Bluemel, W. [VW Kraftwerke GmbH, Wolfsburg (Germany); Kaeferstein, P. [VW Kraftwerke GmbH, Wolfsburg (Germany); Rummel, A.. [Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik (Germany); Moerl, P. [Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik (Germany)

    1992-12-31

    In order to obtain a deeper insight into the configurations developing upon the combustion of hard coal in an industrial circulating fluidized bed, an extensive process analysis was made. The determination of the heat transfer coefficient in the entire range of the steam generator was an essential part of this investigation. The exact calculation of the evaporator turns out to be difficult, as this part is distributed on the furnace, the second pass heating surfaces and the external heat exchanger. Within the scope of the lecture, the determination method as well as its results is presented. Furthermore, a report is made on latest methods for the improvement of the fuel burn-out and on the reduction of the lime consumption, which have resulted from experiments with the modification of combustion-technological parameters such as air ratio, combustion chamber temperatures for various types of coal. To conclude with, a computer-aided databank for the evaluation of various types of coals is being presented. (orig.) [Deutsch] Zum Zwecke einer tieferen Einsicht in die Zusammenhaenge bei der Verbrennung von Steinkohle in einer industriell betriebenen zirkulierenden Wirbelschicht wurde eine umfassende Prozessanalyse durchgefuehrt. Ein wesentlicher Bestandteil dieser Untersuchung war die Ermittlung des Waermedurchgangskoeffizienten im gesamten Bereich des Dampferzeugers. Da sich z.B. der Verdampferteil sowohl in der Brennkammer, in den nachschaltheizflaechen als auch im Fliessbettkuehler befindet, gestaltet sich die exakte Berechnung als sehr kompliziert. Im Rahmen dieses Vortrages werden sowohl die Methodik der Ermittlung als auch deren Ergebnisse vorgestellt. Ausserdem wird sowohl ueber neuere Ansaetze zur Verbesserung des Ausbrandes als auch ueber die Reduzierung des Kalkverbrauches berichtet, die sich aus Ergebnissen von Versuchen unter Aenderung von feuerungstechnischen Parametern wie Luftverhaeltnis, Brennkammertemperaturen und auch verschiedener Kohlen ergeben haben

  6. Non-intrusive measurement and hydrodynamics characterization of gas–solid fluidized beds: a review

    OpenAIRE

    Sun, Jingyuan; Yan, Yong

    2016-01-01

    Gas-solid fluidization is a well-established technique to suspend or transport particles and has been applied in a variety of industrial processes. Nevertheless, our knowledge of fluidization hydrodynamics is still limited for the design, scale-up and operation optimization of fluidized bed reactors. It is therefore essential to characterize the two-phase flow behaviours in gas-solid fluidized beds and monitor the fluidization processes for control and optimization. A range of non-intrusive t...

  7. Ash problem at wood fired fluidized bed plants; Askproblem vid skogsbraensleeldning i fluidbaedd

    Energy Technology Data Exchange (ETDEWEB)

    Hansson, Soeren; Nystroem, Olle; Axby, Fredrik [Sycon Energikonsult AB, Malmoe (Sweden); Andersson, Christer; Kling, Aasa [Vattenfall Utveckling AB, Aelvkarleby (Sweden)

    2001-03-01

    Several ash related problems occurs during conversion from fossil fuels to bio fuels. The most frequent and expensive problem is agglomeration of bed material (in fluidized beds) and fouling on superheating surfaces. The last problem leads to corrosion problem and decreased transfer of heat. This project is the first part of a proposed project focussed on fluidized bed combustion (FB), because FB have become the dominating technology for combustion of biofuels. The project includes this first update of what has been done by different research institutes since 1997 and results of questionnaire on operating problems to owners of fluidized bed plants. A couple of pilot studies and different thermodynamical studies of bed agglomeration with biofuel combustion have been done during the latest years. There are no published reports where the results from agglomeration tests in pilot scale are verified in full scale plants. No project was found which deals with the fouling problem in the cyclone in a circulating fluidized bed. The knowledge of the mechanisms of deposits growth on heat surfaces is incomplete and more research has to be done of what can prevent the deposit growth. Experience from full scale plants shows that the deposits on heat surfaces grows during a period and after that it falls of the heating surface. There is little knowledge of which ash and flue gas conditions that affects these conditions for bio fuel. The operational experience with wood fuels in circulating fluidized beds is that the main problem with bed material is in the inlet and outlet of the cyclone. A total desulfonated of the bed occurs only when there has been other disturbances or because of operator mistakes. There are a number of things which seem to influence on the deposit problems: (1) Boilers with long residence time have less problem than boilers with short residence time. (2) Fuel size. No plant owner have continuos analysis of the fuel size, but combustion with problem have a

  8. Method for using fast fluidized bed dry bottom coal gasification

    Science.gov (United States)

    Snell, George J.; Kydd, Paul H.

    1983-01-01

    Carbonaceous solid material such as coal is gasified in a fast fluidized bed gasification system utilizing dual fluidized beds of hot char. The coal in particulate form is introduced along with oxygen-containing gas and steam into the fast fluidized bed gasification zone of a gasifier assembly wherein the upward superficial gas velocity exceeds about 5.0 ft/sec and temperature is 1500.degree.-1850.degree. F. The resulting effluent gas and substantial char are passed through a primary cyclone separator, from which char solids are returned to the fluidized bed. Gas from the primary cyclone separator is passed to a secondary cyclone separator, from which remaining fine char solids are returned through an injection nozzle together with additional steam and oxygen-containing gas to an oxidation zone located at the bottom of the gasifier, wherein the upward gas velocity ranges from about 3-15 ft/sec and is maintained at 1600.degree.-200.degree. F. temperature. This gasification arrangement provides for increased utilization of the secondary char material to produce higher overall carbon conversion and product yields in the process.

  9. The porosity in a fluidized bed heat transfer model

    NARCIS (Netherlands)

    Visser, G.; Valk, M.

    1993-01-01

    A mathematical model of heat transfer between a fluidized bed and an immersed surface and a model of gas flow and porosity, both recently published, were combined and further modified in the area of low velocities where the particle convective component of heat transfer is low or neglectable. Experi

  10. Acoustic monitoring of a fluidized bed coating process

    DEFF Research Database (Denmark)

    Naelapaa, Kaisa; Veski, Peep; Pedersen, Joan G.;

    2007-01-01

      The aim of the study was to investigate the potential of acoustic monitoring of a production scale fluidized bed coating process. The correlation between sensor signals and the estimated amount of film applied and percentage release, respectively, were investigated in coating potassium chloride...

  11. Mechanism of film formation during granules capsulation in fluidized bed

    OpenAIRE

    Ostroha, Ruslan; Yukhymenko, Mykola

    2013-01-01

    It is proposed to perform granules capsulation process in the device of fluidized bed. Analysis of different approaches to mathematical description of granules growth kinetics was made. Equation of size determination of received granules in the device is proposed including granules growth rate and changes of density of granules distribution according to sizes in film forming process.

  12. Description of emission control using fluidized-bed, heat-exchange technology

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, G.J.; Grogan, P.J.

    1980-06-01

    Environmental effects of fluidized-bed, waste-heat recovery technology are identified. The report focuses on a particular configuration of fluidized-bed, heat-exchange technology for a hypothetical industrial application. The application is a lead smelter where a fluidized-bed, waste-heat boiler (FBWHB) is used to control environmental pollutants and to produce steam for process use. Basic thermodynamic and kinetic information for the major sulfur dioxide (SO/sub 2/) and NO/sub x/ removal processes is presented and their application to fluidized-bed, waste heat recovery technology is discussed. Particulate control in fluidized-bed heat exchangers is also discussed.

  13. 气-液-固自然循环流化床中的流动特性和压降%Flow Properties and Pressure Drop of Gas-Liquid-Solid Natural Circulating in Fluidized-Bed

    Institute of Scientific and Technical Information of China (English)

    齐国鹏; 姜峰; 赵燕禹; 赵国华; 周震; 李修伦

    2009-01-01

    A fluidized-bed evaporator for gas-liquid-solid natural circulation was set up to research the flow and distribution of solid particles and pressure drop of liquid-solid two-phase flow in a heating pipe bundle. With CCD image collecting and processing system,the influences of the particle kinds,particle holdup and additive air amount were studied. The experimental results show that air inlet positions have much effect on the distribution of solid particles in the heating pipe bundle. The form of moving and fluidization of solid particles in up-channel is different from that in down-channel. In up-channel,solid particles make circulating movement with the central part rising and perimeter dropping. As the density decreases,the distribution of solid particles in up-channel gradually becomes uniform. In down-channel,solid particles form two big whirls at both sides of the central axis. As additive air amount increases,the rotation rate of whirls increases. When the air is input from the up-channel,the pressure drop of liquid-solid two-phase flow in the heating pipe bundle increases with the increase of particles holdup and air amount. The pressure drop model of liquid-solid two-phase flow in the heating pipe bundle has been set up,and the calculated data agree well with the experimental results.%建立了气-液-固冷模多管自然循环流化床蒸发器,利用CCD图像采集和处理系统,研究了固体颗粒的种类、含率和通气量等操作参数对于固体颗粒的流化和运动形态、分布以及加热管束中液-固两相流压降的影响.结果表明:通气位置对于固体颗粒在加热管束中的分布影响较大.在上、下管箱中,固体颗粒的运动和流化形态不同.在上管箱中,固体颗粒形成中心上升、四周下降的循环运动,并且随着其密度的降低,固体颗粒在上管箱中的分布逐渐趋向均匀;在下管箱中,固体颗粒在中心轴的两侧形成两个大的旋涡,旋涡的旋转速度随着

  14. Particle Flow Cell Formation at Minimum Fluidization Flow Rates in a Rectangular Gas-Fluidized Bed.

    Science.gov (United States)

    1981-03-01

    Kunii and Levenspiel Model ----------------- 66 C. FLUIDIZED BED VARIABLES THAT AFFECT HEAT TRANSFER ---------------------------------- 69 5 1...and Levenspiel Model -------------------------- 68 25. Heat transfer coefficient vs. mass velocity --------- 72 26. Contact geometry of surface-particle...becomes a very important factor. According to Kunii and Levenspiel [34], distributors should have a sufficient pressure drop to achieve equal flow

  15. EXTERNAL-LOOP AIRLIFT MAGNETICALLY STABILIZED BED--MINIMUM STABILIZATION AND FLUIDIZATION CONDITIONS

    Institute of Scientific and Technical Information of China (English)

    Jordan Hristov

    2005-01-01

    Experimental study of an airlift with a magnetically stabilized bed in the riser bottom has been performed.External magnetic field allows easy control of magnetized bed structure and liquid circulation rate. Minimum stabilization and fluidization conditions have been determined experimentally and by a three-line graphical method. Semi-empirical data correlations of sections of the experimental curves have been performed. Scaling relationships known from non-magnetic airlift are applicable too, but with the assumption that the magnetic field affects the loop friction coefficient only.

  16. CIRCULATING MOVING BED COMBUSTION PROOF OF CONCEPT

    Energy Technology Data Exchange (ETDEWEB)

    Jukkola, Glen

    2010-06-30

    Circulating Moving Bed (CMB) combustion technology has its roots in traditional circulating fluidized bed technology and involves a novel method of solid fuel combustion and heat transfer. CMB technology represents a step change in improved performance and cost relative to conventional PC and FBC boilers. The CMB heat exchanger preheats the energy cycle working fluid, steam or air, to the high temperature levels required in systems for advanced power generation. Unique features of the CMB are the reduction of the heat transfer surfaces by about 60% as a result of the enhanced heat transfer rates, flexibility of operation, and about 30% lower cost over existing technology. The CMB Phase I project ran from July 2001 through March 2003. Its objective was to continue development of the CMB technology with a series of proof of concept tests. The tests were conducted at a scale that provided design data for scale up to a demonstration plant. These objectives were met by conducting a series of experiments in ALSTOM Power’s Multi-use Test Facility (MTF). The MTF was modified to operate under CMB conditions of commercial interest. The objective of the tests were to evaluate gas-to-solids heat transfer in the upper furnace, assess agglomeration in the high temperature CMB bubbling bed, and evaluate solids-to-tube heat transfer in the moving bed heat exchanger. The Phase I program results showed that there are still some significant technical uncertainties that needed to be resolved before the technology can be confidently scaled up for a successful demonstration plant design. Work remained in three primary areas: • scale up of gas to solid heat transfer • high temperature finned surface design • the overall requirements of mechanical and process design. The CMB Phase II workscope built upon the results of Phase I and specifically addressed the remaining technical uncertainties. It included a scaled MTF heat transfer test to provide the necessary data to scale up gas

  17. Operation of a fluidized-bed denitrification bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, P.A.

    1978-11-15

    In the fluidized-bed denitrification process developed, bacteria are allowed to grow and attach themselves to 0.25 to 0.60-mm-OD coal particles, and nitrate-containing solution is pumped up through the column at a velocity sufficient to fluidize the bacteria-coated coal particles. The denitrification bacteria convert the nitrate ions to nitrogen gas. A 10-cm-ID column has been operated by Oak Ridge Y-12 Plant personnel to test the scale-up and operational characteristics of the fluidized bed process. The reactor consists of a tapered bottom section for flow distribution, several straight 10-cm-ID cylindrical sections, and a tapered top section for solid/liquid disengaging. Increasing the diameter of the reactor by a factor of two did not cause any decrease in reactor performance. The fluidized-bed reactor is characterized by short-residence-time requirements (about 2 minutes per meter of height), and by high, but variable, denitrification rates (2 to 35 g NO/sub 3//sup -/-N/dm/sup 3//day). The reactor is best suited for relatively low-concentration nitrate wastes (<1 wt% NO/sub 3//sup -/). The economics of using the reactor for high-concentration wastes (>20 wt% NO/sub 3//sup -/) is less favorable, but still may be competitive with other reactor types. 9 figs, 2 tables.

  18. HYDRODYNAMIC CHARACTERISTICS OF FLUIDIZED BEDS CONTAINING LARGE POLYDISPERSED PARTICLES

    Directory of Open Access Journals (Sweden)

    K. TANNOUS

    1998-03-01

    Full Text Available This paper presents a hydrodynamic study of fluidized beds containing large polydispersed particles (B and D categories of Geldart’s classification. The experiments have been carried out with particle samples characterized by the Rosin-Rammler-Sperling (RRS size distribution. The parameters analyzed in this study are the dispersion index and the average particle diameter obtained from the RRS size distribution model. Correlations to estimate the initial and complete fluidization velocities and the segregation velocity as a function of these two size distribution parameters have been established.

  19. Anaerobic digestion of dairy wastewater by inverse fluidization: the inverse fluidized bed and the inverse turbulent bed reactors.

    Science.gov (United States)

    Arnaiz, C; Buffiere, P; Elmaleh, S; Lebrato, J; Moletta, R

    2003-11-01

    This paper describes the application of the inverse fluidization technology to the anaerobic digestion of dairy wastewater. Two reactors were investigated: the inverse fluidized bed reactor and the inverse turbulent reactor. In these reactors, a granular floating solid is expanded by a down-flow current of effluent or an up-flow current of gas, respectively. The carrier particles (Extendospheres) were chosen for their large specific surface area (20,000 m2m(-3)) and their low energy requirements for fluidization (gas velocity of 1.5 mm s(-1), 5.4 m h(-1)). Organic load was increased stepwise by reducing hydraulic retention time from more than 60 days to 3 days, while maintaining constant the feed COD concentration. Both reactors achieved more than 90% of COD removal, at an organic loading rate of 10-12 kgCOD m(-3) d(-1), respectively. The performances observed were similar or even higher than that of other previously tested fluidized bed technologies treating the same wastewater. It was found that the main advantages of this system are: low energy requirement, because of the low fluidization velocities required; there is no need of a settling device, because solids accumulate at the bottom of the reactor, so they can be easily drawn out and particles with high-biomass content can be easily recovered. Lipid phosphate concentration has been revealed as a good method for biomass estimation in biofilms since it only includes living biomass.

  20. Beckmann rearrangement of cyclohexanone oxime to {epsilon}-caprolactam using a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Dahlhoff, G.; Hoelderich, W.F. [Technische Hochschule Aachen (Germany)

    1999-07-01

    The application of a fluidized bed reactor on the heterogeneously catalyzed Beckmann rearrangement of cyclohexanone oxime to {epsilon}-caprolactam is presented. For this purpose the classic industrial synthesis route is compared to the new route catalyzed by [B]-MFI zeolite which proved to be the most suitable. To prepare the use of the catalyst the thermodynamics were calculated showing that the residence time of the reactants are of great importance. A regeneration model was developed resulting in a mathematical equation for the regeneration time calculated to seven hours under oxidative conditions. A 40 day regeneration experiment demonstrated the excellent regeneration behaviour of the chosen catalyst showing no decrease in activity after 40 recycle treatments. Finally, the experiments in a constructed non circulating fluidized bed showed good yields and selectivities (99%/91%) completely comparable to the actual synthesis route but avoiding 4 t ammonia sulphate/t product. (orig.)

  1. Solids mixing in bubbling fluidized beds: CFD-based analysis of Bubble Dynamics and Time Scales

    Science.gov (United States)

    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.

  2. Comparison of packed bed and fluidized bed membrane reactors for methane reforming

    NARCIS (Netherlands)

    Gallucci, Fausto; Sint Annaland, van Martin; Kuipers, J.A.M.

    2009-01-01

    In this work the performance of different membrane reactor concepts, both fluidized bed and packed bed membrane reactors, have been compared for the reforming of methane for the production of ultra-pure hydrogen. Using detailed theoretical models, the required membrane area to reach a given conversi

  3. Theoretical comparison of packed bed and fluidized bed membrane reactors for methane reforming

    NARCIS (Netherlands)

    Gallucci, Fausto; Sint Annaland, van Martin; Kuipers, J.A.M.

    2010-01-01

    In this theoretical work the performance of different membrane reactor concepts, both fluidized bed and packed bed membrane reactors, has been compared for ultra-pure hydrogen production via methane reforming. Using detailed theoretical models, the required membrane area to reach a given conversion

  4. EFFECT OF VERTICAL BAFFLES ON PARTICLE MIXING AND DRYING IN FLUIDIZED BEDS OF GROUP D PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Chung Lim Law; Siti Masrinda Tasirin; Wan Ramli Wan Daud; Derek Geldart

    2003-01-01

    This study reports the effect of vertical baffles on the group D powder mixing and drying characteristics in a batch fluidized bed dryer. Results obtained in this study showed that operating the fluidized bed dryer with vertical baffles gave better particle mixing. This is due to the fact that the vertical baffles acted to limit the growth of small bubbles into large bubbles and the small bubbles caused more vigorous mixing in the bed of particles before finally erupting at the bed surface. Thus, insertion of vertical baffles is a useful way to process group D particles in a fluidized bed, especially when the fluidized bed is large.

  5. Effect of particle size and interparticle force on the fluidization behavior of gas-fluidized beds.

    Science.gov (United States)

    Valverde, J M; Castellanos, A; Mills, P; Quintanilla, M A S

    2003-05-01

    Gas-fluidized powders of fine particles display a fluidlike regime in which the bed does not have a yield strength, it expands uniformly as the gas velocity is increased and macroscopic bubbles are absent. In this paper we test the extension of this fluidlike regime as a function of particle size and interparticle attractive force. Our results show that for sufficiently large particles, bubbling initiates just after the solidlike fluidized regime as it is obtained experimentally by other workers. A scaling behavior of the solid-phase pressure in the fluidlike regime and a predictive criterion for the onset of macroscopic bubbling are analyzed in the light of these results.

  6. Sorption-enhanced steam methane reforming in fluidized bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Kim

    2006-10-15

    reformer-calciner system is likely to be rather low, so that only a fraction of the sorbent is utilized, highlighting the importance of the carbonation model at lower conversions. A dual fluidized bed reactor for the SE-SMR system was modeled by using a simple two-phase hydrodynamic model, the experimentally derived carbonation kinetics and literature values for the kinetics of steam reforming and water gas shift reactions. The model delineates important features of the process. Hydrogen concentrations of >98 mole% were predicted for temperatures {approx}600 C and a superficial gas velocity of 0.1 m/s. The reformer temperature should not be lower than 540 C or greater than 630 C for carbon capture efficiencies to exceed 90%. Operating at relatively high solid circulation rates to reduce the need for fresh sorbent, is predicted to give higher system efficiencies than for the case where fresh solid is added. This finding is attributed to the additional energy required to decompose both CaCO{sub 3} and MgCO{sub 3} in fresh dolomite. Moreover, adding fresh sorbent is likely to result in catalyst loss in the purge stream, requiring sorbents with lifetimes comparable to those of the catalyst. Thermo gravimetric analysis (TGA) was used to study the reversible CO{sub 2}-uptake of sorbents. In general, the multi-cycle capacity of the dolomite was found rather poor. Therefore, synthetic sorbents that maintain their capacities upon multiple reforming-calcination cycles were investigated. A low-temperature liquid phase co-precipitation method was used for synthesis of Li{sub 2}ZrO{sub 3} and Na{sub 2}ZrO{sub 3}. Li{sub 2}ZrO{sub 3} showed a superior multi-cycle capacity compared to Arctic dolomite in TGA, but the rate of reaction in diluted CO{sub 2} atmospheres was very slow. The synthesized Na{sub 2}ZrO{sub 3} proved to have both fast carbonation kinetics and stable multi-cycle performance. However, regeneration in the presence of carbon dioxide was not easily accomplished. The

  7. MODELING TWO-PHASE FLOW IN PULSED FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    Dayou Liu; Guodong Jin

    2003-01-01

    Mathematical models for pulsed fluidization are systematically discussed. Several undetermined constitutive relationships are included in the General Two-Fluid Model (GTFM), the adjustable parameters of which are always chosen at will to some extent. Although there are no adjustable parameters in the Basic Two-Fluid Model (BTFM), its eigenvalues are complex numbers and it is ill-posed for initial-value problems. The Local Equilibrium Model (LEM), a further simplification of BTFM, is discussed at length. Although the model is very simple, it is highly capable of simulating complex processes in pulsed fluidization over a broad range of operating parameters, and its numerical results well fit experimental results in both the variation of bed height and the distribution of particle concentration as fluidizing velocity varies.

  8. 金精矿提金三相循环流化床系统的神经网络建模%Neural Network Modeling of System of Extracting Gold from Gold Concentrate with Three-phase Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    李松; 李征; 赵洋; 李登新

    2011-01-01

    三相循环流化床床层压力是影响提金效率的一个重要因素,但床层压力大小受进气速度、固含率、金精矿粒径大小、循环流化床自身设计结构等多种因素影响,关系复杂,难以建立精确的数学模型;针对以上问题,首先通过实验确定了影响床层压力大小的主次因素,为简化问题进行建模做了准备;然后对三相循环流化床提金过程的压力特性进行多工况实验,采用基于LM( Levenberg- Marquardt)算法的BP神经网络建立了金精矿提金三相循环流化床床层压力的神经网络模型,并进行了校验;研究结果表明该算法收敛速度快,所建模型精度高且泛化能力强,该模型为三相循环流化床的监控提供了基础.%The stratified pressure of Three-phase Circulating Fluidized Bed (TCFB) is one important factor which affects the efficiency of extracting gold from gold concentrate. But the size of the stratified pressure is affected by many factors, such as the rate of the flowing gas. Solid holdup, the design structure of TCFB, etc. And their relationship is complicated, it' s difficult to establish accurate mathematical model. Aimed at this problem, firstly, the main factors and the secondary factors which affect the size of the stratified pressure have been determined by experiments, based on this, the problem was simplified to prepare for the modeling. Then the stratified pressure of TCFB in extracting gold from gold concentrate process was experimentally investigated, and taking advantage of BP neural network based on Levenberg - Marquardt (LM) algorithm, the neural network model is established and verified. The result showed that the LM algorithm has a rapid convergent speed, the model has high precision and good generalization ability, and the model provides a foundation to monitor TCFB.

  9. Bubbles trapped in a fluidized bed: Trajectories and contact area

    Science.gov (United States)

    Poryles, Raphaël; Vidal, Valérie; Varas, Germán

    2016-03-01

    This work investigates the dynamics of bubbles in a confined, immersed granular layer submitted to an ascending gas flow. In the stationary regime, a central fluidized zone of parabolic shape is observed, and the bubbles follow different dynamics: either the bubbles are initially formed outside the fluidized zone and do not exhibit any significant motion over the experimental time or they are located inside the fluidized bed, where they are entrained downwards and are, finally, captured by the central air channel. The dependence of the air volume trapped inside the fluidized zone, the bubble size, and the three-phase contact area on the gas injection flow rate and grain diameter are quantified. We find that the volume fraction of air trapped inside the fluidized region is roughly constant and of the order of 2%-3% when the gas flow rate and the grain size are varied. Contrary to intuition, the gas-liquid-solid contact area, normalized by the air injected into the system, decreases when the flow rate is increased, which may have significant importance in industrial applications.

  10. The effect of vibration on bed voidage behaviors in fluidized beds with large particles

    Energy Technology Data Exchange (ETDEWEB)

    Jin, H.; Zhang, J.; Zhang, B.

    2007-07-01

    The effects of vibration parameters, operating conditions and material properties on bed voidage were investigated using an optical fiber probe approach in a vibrating fluidized bed with a diameter of 148 mm. Variables studied included frequency (0-282 s{sup -1}), amplitude (0 mm-1 mm), bed height (0.1 m-0.4 m) as well as four kinds of particles (belonging to Geldart's B and D groups). The axial and radial voidage distribution with vibration is compared with that without vibration, which shows vibration can aid in the fluidization behaviors of particles. For a larger vibration amplitude, the vibration seriously affects bed voidage. The vibration energy can damp out for particle layers with increasing the bed height. According to analysis of experimental data, an empirical correlation for predicting bed voidage, giving good agreement with the experimental data and a deviation within {+-}15%, was proposed. 20 refs., 8 figs., 2 tabs.

  11. The effect of vibration on bed voidage behaviors in fluidized beds with large particles

    Directory of Open Access Journals (Sweden)

    H. Jin

    2007-09-01

    Full Text Available The effects of vibration parameters, operating conditions and material properties on bed voidage were investigated using an optical fiber probe approach in a vibrating fluidized bed with a diameter of 148 mm. Variables studied included frequency (0-282 s-1, amplitude (0 mm-1 mm, bed height (0.1 m-0.4 m as well as four kinds of particles (belonging to Geldart's B and D groups. The axial and radial voidage distribution with vibration is compared with that without vibration, which shows vibration can aid in the fluidization behaviors of particles. For a larger vibration amplitude, the vibration seriously affects bed voidage. The vibration energy can damp out for particle layers with increasing the bed height. According to analysis of experimental data, an empirical correlation for predicting bed voidage, giving good agreement with the experimental data and a deviation within ±15%, was proposed.

  12. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    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)

  13. Nitrogen Chemistry in Fluidized Bed Combustion of Coal

    DEFF Research Database (Denmark)

    Jensen, Anker Degn

    The present Ph.D thesis describes an experimental and theoretical investigation of the formation and destruction of nitrogen oxides (NOx and N2O) in fluidized bed combustion (FBC) of coal. A review of the current knowledge of nitrogen chemistry in FBC is presented. The review covers both laboratory...... for the emission of NOx from FBC has been developed as part of a JOULE project. The model is based on the two-phase theory of fluidization for the bed with a Kunii-Levenspiel type freeboard model and includes submodels for coal devolatilization, combustion of volatiles and char and a detailed model of NO formation...... plant were used for model verification. The simulations of the NO emission during staged combustion and NH3 injection for NO reduction were in qualitative agreement with the experimental data. A parametric study of the influence of operating conditions on the conversion of fuel-N to NO showed...

  14. Particle-scale simulation of fluidized bed with immersed tubes

    Institute of Scientific and Technical Information of China (English)

    Yongzhi ZHAO; Maoqiang JIANG; Yi CHENG

    2008-01-01

    In order to simulate gas-solids flows with complex geometry,the boundary element method was incorporated into the implementation of a combined model of computational fluid dynamics and discrete element method.The resulting method was employed to simulate hydrodynamics in a fluidized bed with immersed tubes.The transient simulation results showed particle and bubble dynamics.The bubble coalescence and break-up behavior when passing the immersed tubes was successfully predicted.The gas-solid flow pattern in the fluidized bed is changed greatly because of the immersed tubes.As particles and gas are come in contact with the immersed tubes,the gas bubbles will be deformed.The collisions between particles arid tubes will make the tubes sur-rounded by air pockets most of the time and this is unfavorable for the heat transfer between particles and tubes.

  15. Carbon Shale Combustion in the Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Olek Małgorzata

    2014-06-01

    Full Text Available The purpose of this article is to present the possibilities of coal shale combustion in furnaces with bubbling fluidized bed. Coal shale can be autothermally combusted in the fluidized bed, despite the low calorie value and high ash content of fuel. Established concentrations of CO (500 ppm and VOC (30 mg/m3 have indicated a high conversion degree of combustible material during combustion process. Average concentrations of SO2 and NOx in the flue gas were higher than this received from the combustion of high quality hard coal, 600 ppm and 500 ppm, respectively. Optional reduction of SO2 and NOx emission may require the installation of flue gas desulphurization and de-NOx systems.

  16. Heat transfer characteristics of the fluidized bed through the annulus

    Science.gov (United States)

    Shedid, Mohamed H.; Hassan, M. A. M.

    2016-09-01

    The annular fluidized bed can be regarded as a promising technique for waste heat recovery applications. This study investigates on the determination of steady state values of the average heat transfer on the surface of the inner tube under different operating conditions that include: (1) input heat flux ranging from 557 to 1671 W/m2, (2) superficial air velocity ranging between 0.12 and 0.36 m/s, (3) initial bed height ranging from 25 to 55 cm, (4) ratio of the inner to the outer diameters ranging from 1/6 to 1/2 and Kaolin particle diameters ranging between 282 and 550 µm. The average values of the heat transfer coefficient along the inner tube (consisting of the fluidized and free board sections) are also deduced. An empirical correlation for calculating the Nusselt number is obtained for the given parameters and ranges.

  17. An investigation into the fluidization and heat transfer of low density particles in a fluidized bed with applications

    Science.gov (United States)

    Modlin, J. M.

    1985-05-01

    The lack of reliable data on the fluidization and heat transfer characteristics of low density particles in a fluidized bed has prompted an experimental and analytical investigation into this subject. Seven groups of particles ranging in diameter from 0.25 mm to 2.0 mm and density from 2.5 to 32 pcf have been successfully fluidized and shown to be generally well predicted by classical fluidization and fluidized bed heat transfer theory. Two other groups of particles, also in this approximate range of particle diameter and density, are, however, unable to be fluidized due to significant inter-particle and static electric attractions. Using the experimental data and results as a basis of analysis, two application of low density particle fluidization in a building efficient energy management program are discussed. A fluidized bed can be incorporated into the wall cavity of a building for use as either a collector of solar energy or as a heat exchange medium in a building space heating/cooling program. As a solar collector, it is shown that the low density particle fluidized bed would thermally perform between comparable conventional liquid and air-cooled flat plate solar collectors. It would require less water pumping power and plumbing than the liquid collector and less air pumping power than the air collector.

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

    Institute of Scientific and Technical Information of China (English)

    Tingwen Li; Pradeep Gopalakrishnana; Rahul Garg; Mehrdad Shahnam

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Tingwen, Li; Gopalakrishnan, Pradeep; Garg, Rahul; Shahnam, Mehrdad

    2011-10-01

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

  20. Experiments and Modelling of Coal Pyrolysis under Fluidized Bed Conditions

    Institute of Scientific and Technical Information of China (English)

    ZhangYongzhe; XuXiangdong; 等

    1999-01-01

    The pyrolysis behavior of two Chinese coals has been investigated in a laboratory-scale bubbling fluidized bed system in Siegen University,Germany,Experimental equipment and procedure are introduced.The amounts of pyrolysis species of each coal were measured,calcuated and compared.A new method was presented to determine the needed parameters in FG-DVC model with the experimental results instead of other much more complicated experiments.

  1. Chemical looping combustion of coal in interconnected fluidized beds

    Institute of Scientific and Technical Information of China (English)

    SHEN LaiHong; ZHENG Min; XIAO Jun; ZHANG Hui; XIAO Rui

    2007-01-01

    Chemical looping combustion is the indirect combustion by use of oxygen carrier.It can be used for CO2 capture in power generating processes. In this paper,chemical looping combustion of coal in interconnected fluidized beds with inherent separation of CO2 is proposed. It consists of a high velocity fluidized bed as an air reactor in which oxygen carrier is oxidized, a cyclone, and a bubbling fluidized bed as a fuel reactor in which oxygen carrier is reduced by direct and indirect reactions with coal. The air reactor is connected to the fuel reactor through the cyclone. To raise the high carbon conversion efficiency and separate oxygen carrier particle from ash, coal slurry instead of coal particle is introduced into the bottom of the bubbling fluidized bed. Coal gasification and the reduction of oxygen carrier with the water gas take place simultaneously in the fuel reactor. The flue gas from the fuel reactor is CO2 and water. Almost pure CO2 could be obtained after the condensation of water. The reduced oxygen carrier is then returned back to the air reactor, where it is oxidized with air. Thermodyanmics analysis indicates that NiO/Ni oxygen carrier is the optimal one for chemical looping combustion of coal.Simulation of the processes for chemical looping combustion of coal, including coal gasification and reduction of oxygen carrier, is carried out with Aspen Plus software. The effects of air reactor temperature, fuel reactor temperature, and ratio of water to coal on the composition of fuel gas, recirculation of oxygen carrier particles, etc., are discussed. Some useful results are achieved. The suitable temperature of air reactor should be between 1050-1150Cand the optimal temperature of the fuel reactor be between 900-950℃.

  2. Chemical looping combustion of coal in interconnected fluidized beds

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chemical looping combustion is the indirect combustion by use of oxygen carrier. It can be used for CO2 capture in power generating processes. In this paper, chemical looping combustion of coal in interconnected fluidized beds with inherent separation of CO2 is proposed. It consists of a high velocity fluidized bed as an air reactor in which oxygen carrier is oxidized, a cyclone, and a bubbling fluidized bed as a fuel reactor in which oxygen carrier is reduced by direct and indirect reactions with coal. The air reactor is connected to the fuel reactor through the cyclone. To raise the high carbon conversion efficiency and separate oxygen carrier particle from ash, coal slurry instead of coal particle is introduced into the bottom of the bubbling fluidized bed. Coal gasification and the reduction of oxygen carrier with the water gas take place simultaneously in the fuel reactor. The flue gas from the fuel reactor is CO2 and water. Almost pure CO2 could be obtained after the con- densation of water. The reduced oxygen carrier is then returned back to the air reactor, where it is oxidized with air. Thermodyanmics analysis indicates that NiO/Ni oxygen carrier is the optimal one for chemical looping combustion of coal. Simulation of the processes for chemical looping combustion of coal, including coal gasification and reduction of oxygen carrier, is carried out with Aspen Plus software. The effects of air reactor temperature, fuel reactor temperature, and ratio of water to coal on the composition of fuel gas, recirculation of oxygen carrier par- ticles, etc., are discussed. Some useful results are achieved. The suitable tem- perature of air reactor should be between 1050―1150℃and the optimal temperature of the fuel reactor be between 900―950℃.

  3. Fluidized bed control system based on inverse system method

    Institute of Scientific and Technical Information of China (English)

    SONG Fu-hua; LI Ping

    2005-01-01

    The invertible of the Large Air Dense Medium Fluidized Bed (ADMFB) were studied by introducing the concept of the inverse system theory of nonlinear systems.Then the ADMFB, which was a multivariable, nonlinear and coupled strongly system,was decoupled into independent SISO pseudo-linear subsystems. Linear controllers were designed for each of subsystems based on linear systems theory. The practice output proves that this method improves the stability of the ADMFB obviously.

  4. Gasification of wood in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, L.C. de; Marti, T.; Frankenhaeuser, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    A first series of gasification experiments with our fluidized bed gasifier was performed using clean sawdust as fuel. The installation and the analytical systems were tested in a parametric study in which gasification temperature and equivalence ratio were varied. The data acquired will serve to establish the differences between the gasification of clean wood and the gasification of Altholz (scrapwood) and wood/plastics mixtures. (author) 1 fig., 3 tabs., 5 refs.

  5. Spectral methods applied to fluidized bed combustors. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R.C.; Christofides, N.J.; Junk, K.W.; Raines, T.S.; Thiede, T.D.

    1996-08-01

    The objective of this project was to develop methods for characterizing fuels and sorbents from time-series data obtained during transient operation of fluidized bed boilers. These methods aimed at determining time constants for devolatilization and char burnout using carbon dioxide (CO{sub 2}) profiles and from time constants for the calcination and sulfation processes using CO{sub 2} and sulfur dioxide (SO{sub 2}) profiles.

  6. Anaerobic degradation of linear alkylbenzene sulfonate in fluidized bed reactor

    OpenAIRE

    2010-01-01

    An anaerobic fluidized bed reactor was used to assess the degradation of the surfactant linear alkylbenzene sulfonate (LAS). The reactor was inoculated with sludge from an UASB reactor treating swine wastewater and was fed with a synthetic substrate supplemented with LAS. Sand was used as support material for biomass immobilization. The reactor was kept in a controlled temperature chamber (30±1 ºC) and operated with a hydraulic retention time (HRT) of 18 h. The LAS concentration was gradually...

  7. Sorption-enhanced steam methane reforming in fluidized bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Kim

    2006-10-15

    reformer-calciner system is likely to be rather low, so that only a fraction of the sorbent is utilized, highlighting the importance of the carbonation model at lower conversions. A dual fluidized bed reactor for the SE-SMR system was modeled by using a simple two-phase hydrodynamic model, the experimentally derived carbonation kinetics and literature values for the kinetics of steam reforming and water gas shift reactions. The model delineates important features of the process. Hydrogen concentrations of >98 mole% were predicted for temperatures {approx}600 C and a superficial gas velocity of 0.1 m/s. The reformer temperature should not be lower than 540 C or greater than 630 C for carbon capture efficiencies to exceed 90%. Operating at relatively high solid circulation rates to reduce the need for fresh sorbent, is predicted to give higher system efficiencies than for the case where fresh solid is added. This finding is attributed to the additional energy required to decompose both CaCO{sub 3} and MgCO{sub 3} in fresh dolomite. Moreover, adding fresh sorbent is likely to result in catalyst loss in the purge stream, requiring sorbents with lifetimes comparable to those of the catalyst. Thermo gravimetric analysis (TGA) was used to study the reversible CO{sub 2}-uptake of sorbents. In general, the multi-cycle capacity of the dolomite was found rather poor. Therefore, synthetic sorbents that maintain their capacities upon multiple reforming-calcination cycles were investigated. A low-temperature liquid phase co-precipitation method was used for synthesis of Li{sub 2}ZrO{sub 3} and Na{sub 2}ZrO{sub 3}. Li{sub 2}ZrO{sub 3} showed a superior multi-cycle capacity compared to Arctic dolomite in TGA, but the rate of reaction in diluted CO{sub 2} atmospheres was very slow. The synthesized Na{sub 2}ZrO{sub 3} proved to have both fast carbonation kinetics and stable multi-cycle performance. However, regeneration in the presence of carbon dioxide was not easily accomplished. The

  8. Fluidized and vibrofluidized shallow beds of fresh leaves

    Institute of Scientific and Technical Information of China (English)

    Renata de Aquino Brito Lima; Maria do Carmo Ferreira

    2011-01-01

    The fluid dynamics behavior of shallow fluidized and vibrofluidized beds operating with fresh leaves was investigated with the aim of exploring drying applications in a modified conveyor belt (MCB) system, which may be operated in a fixed- or fiuidized-bed mode. Leaves of the specimens Duranta repens,Schinus molle, Coleus barbatus, Buxus sempervirens, and Bougainvillea spectabilis were tested with a range of sphericities from 0.063 to 0.213. bulk densities from 0.038 to 0.251 g/cm3. apparent densities from 0.52 to 0.97 g/cm3 and ratios of total surface area to volume from 21 to 224 cm-t. Fluidization characteristic curves were obtained by measuring pressure drops versus air velocity in a rectangular column of 0.20m x 0.11 m cross section. It was not possible to reach real fluidized regimes with the leaves due to strongly non-homogeneous beds. Nevertheless, the characteristic curves allowed for the identification of a transition regime from fixed- to expanded-beds, and parameters such as air velocity and pressure drop obtained from the experimental data at the transition were reproducible for specimens with lower surface area or lower specific gravity (i.e., Duranta repens, Schinus molle, and Bougainvillea spectabilis).The transition velocity and pressure drop could not be predicted by the literature developed for estimat0.5 and 1.0 helped to reduce channeling and decrease the transition velocities from fixed to expanded regimes although it did not affect the pressure drops after the bed expansion. The results suggest that drying fresh leaves using the MCB dryer operating in a fluidized mode would not be feasible because none of the materials investigated attained a high-quality fluidization. Operation of the MCB dryer may be possible by alternating between the fixed and vibrofluidized modes. For the specimens tested, the drying should be performed in a range of air velocities from 0.50 to 0.60 m/s to ensure that the operation is in a vibrofluidized regime. The

  9. State of the art of pressurized fluidized bed combustion systems

    Energy Technology Data Exchange (ETDEWEB)

    Graves, R.L.

    1980-09-01

    This report was prepared at the request of the Tennessee Valley Authority (TVA) to clarify the development status of the pressurized fluidized bed combustor (PFBC) and to place in perspective the problems which are yet to be solved before commercialization of the concept is practical. This report, in essence, supersedes the interim report published in 1979, Assessment of the State of the Art of Pressurized Fluidized Bed Combustion Systems. A brief overview of the PFBC concept is included citing potential advantages and disadvantages relative to atmospheric fluidized bed combustion (AFBC) and conventional pulverized coal plants. A survey of existing and developing PFBC experimental facilities is presented in some detail which includes the major accomplishments at the respective facilities. Recent data on plant emissions, turbine/gas cleanup systems, and overall efficiency are provided. Findings of several design studies are also discussed. The results of recent gas turbine and cascade tests have been encouraging although the full assessment of the accomplishments have not been made. The delay in construction of the Grimethorpe plant causes further delay in proof-testing full-size, rotating turbomachinery. Several parameters are recommended for further assessment in design studies including: (1) effect of turbine life on cost of power; and (2) effect of reduced gas turbine inlet temperature and pressure on cost of power.

  10. Influence of rolling friction on single spout fluidized bed simulation

    Institute of Scientific and Technical Information of China (English)

    Christoph Goniva; Christoph Kloss; Niels G. Deen; Johannes A. M. Kuipers; Stefan Pirker

    2012-01-01

    In this paper we study the effect of rolling friction on the dynamics in a single spout fluidized bed using Discrete Element Method (DEM) coupled to Computational Fluid Dynamics (CFD).In a first step we neglect rolling friction and show that the results delivered by the open source CFD-DEM framework applied in this study agree with previous simulations documented in literature.In a second step we include a rolling friction sub-model in order to investigate the effect of particle non-sphericity.The influence of particle-particle as well as particle-wall rolling friction on the flow in single spout fluidized bed is studied separately.Adequate rolling friction model parameters are obtained using first principle DEM simulations and data from literature.Finally,we demonstrate the importance of correct modelling of rolling friction for coupled CFD-DEM simulations of spout fluidized beds.We show that simulation results can be improved significantly when applying a rolling friction model,and that experimental data from literature obtained with Positron Emission Particle Tracking (PEPT) technique can be satisfactorily reproduced.

  11. COMPUTATIONALLY INTELLIGENT MODELLING AND CONTROL OF FLUIDIZED BED COMBUSTION PROCESS

    Directory of Open Access Journals (Sweden)

    Ivan T Ćirić

    2011-01-01

    Full Text Available In this paper modelling and control approaches for fluidized bed combustion process have been considered, that are based on the use of computational intelligence. Proposed adaptive neuro-fuzzy-genetic modelling and intelligent control strategies provide for efficient combining of available expert knowledge with experimental data. Firstly, based on the qualitative information on the desulphurization process, models of the SO2 emission in fluidized bed combustion have been developed, which provides for economical and efficient reduction of SO2 in FBC by estimation of optimal process parameters and by design of intelligent control systems based on defined emission models. Also, efficient fuzzy nonlinear FBC process modelling strategy by combining several linearized combustion models has been presented. Finally, fuzzy and conventional process control systems for fuel flow and primary air flow regulation based on developed models and optimized by genetic algorithms have also been developed. Obtained results indicate that computationally intelligent approach can be successfully applied for modelling and control of complex fluidized bed combustion process.

  12. Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass

    Science.gov (United States)

    Fotovat, Farzam

    regard, an active biomass particle is tracked for a long period of time and its instantaneous position is recorded. The acquired data is then processed to achieve the time-averaged concentration profile of biomass particles. This profile represents the segregation of biomass particles, which tend to accumulate in the upper levels of the bed. Changes in the fraction of biomass with increasing gas velocity are inferred from the local changes of the time-averaged pressure drop values at the top of the bed. To determine the parameters affecting the movement and segregation of biomass particles, their circulatory motion is also scrutinized using the RPT data. The circulation of biomass is impeded when the load of biomass rises at U=0.36 m/s, resulting in a more pronounced segregation of sand and biomass. The opposite trend is observed at U=0.64 m/s. This prompts a more uniform distribution of particles along the bed and brings about a higher degree of mixing. The average rise velocity of biomass is 0.2 times the bubble velocity, regardless of the biomass load or fluidization velocity. A one-dimensional model is proposed to predict the volume fraction of biomass along the bed. Some of the terms of this model are linked to the fluidizing behavior of biomass particles as deduced from the RPT findings. The fluidization of sand and cylindrical biomass particles is also simulated using the BARRACUDA CPFD software, which is based on the Lagrangian-Eulerian approach. Simulation and experimental results are compared in order to evaluate the capability of the numerical approach to predict the bubbling characteristics of the sand-biomass mixture for systems differing in composition and fluidization velocity. The last part of this thesis is devoted to the separation of the main components of the shredded bulky waste. A step-wise process has been developed based on the elutriation and density segregation techniques. After removal of the light and interwoven species of the shredded waste

  13. Prediction of product distribution in fine biomass pyrolysis in fluidized beds based on proximate analysis.

    Science.gov (United States)

    Kim, Sung Won

    2015-01-01

    A predictive model was satisfactorily developed to describe the general trends of product distribution in fluidized beds of lignocellulosic biomass pyrolysis. The model was made of mass balance based on proximate analysis and an empirical relationship with operating parameters including fluidization hydrodynamics. The empirical relationships between product yields and fluidization conditions in fluidized bed pyrolyzers were derived from the data of this study and literature. The gas and char yields showed strong functions of temperature and vapor residence time in the pyrolyzer. The yields showed a good correlation with fluidization variables related with hydrodynamics and bed mixing. The predicted product yields based on the model well accorded well with the experimental data.

  14. 简约型660 MW超超临界循环流化床锅炉设计开发%Conceptual Design of a Simplified 660 MW Ultra-supercritical Circulating Fluidized Bed Boiler

    Institute of Scientific and Technical Information of China (English)

    吕俊复; 张缦; 杨海瑞; 刘青; 刘志强; 赵勇纲

    2014-01-01

    The design consideration of a 660 MW ultra-supercritical circulating fluidized bed (CFB) boiler was discussed. The conceptual design of simplified 660 MW ultra-supercritical CFB boiler was suggested. In this boiler, there is only one distributor to avoid the bed inventory overturn between pant-legs. All the heating surface in the loop are located in the uppers of the furnace instead of external heat exchanger. The front water wall is embattlement shape, the water wall surface is enlarged compared with that the normal one because the length of the wall is expended for the same furnace sectional area. And the height of the furnace is only 48.2 m. The secondary air nozzles are located in the trough to the furnace of the embattlement shape wall, the distance between the front wall and rear wall is decreased to improve the Oxygen diffusion in the gas solid two phase flow. There is an embattlement in the rear wall between the adjacent cyclones. And the furnace alone the width direction is divided into four units. Thus this design is unit design. The operation practices shows that the cut size of the fly ash is not upward trend when the cyclone diameter increases. This indicates that the collection efficiency of the cyclone does not decrease when the cyclone diameter increases, which proves the feasibility of the cyclone with 10.85 m diameter in this design. The structure of the simplified 660 MW supercritical CFB boiler was described, and the performance was also predicted.%分析了660 MW超超临界CFB锅炉的设计原则和依据,提出了简约型660 MW超超临界CFB锅炉方案。采用单布风,消除翻床现象;不设置外置式换热器,能够满足性能要求。前水冷壁采用锯齿形结构,在截面积不变的条件下扩大周界长度,确保一次上升水冷壁的面积,炉膛高度仅为48.2 m;二次风在齿凹处给入,降低了二次风处炉膛实际深度,利于改善炉膛中心区的供氧。后墙水冷壁在两个分

  15. Research report of FY 1997 on the environmentally acceptable coal utilization system introduction support project. Follow-up project on circulating fluidized bed boiler introduction (Calaca Batangas Thermal Power Station); 1997 nendo chosa hokokusho. Kankyo chowagata sekitan riyo system donyu shien jigyo (junkan ryudosho boiler ni kakawaru follow up jigyo (Calaca Batangas karyoku hatsudensho))

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    For the follow-up project, to promote the diffusion of results of the clean coal technology (CCT) model projects, experts of circulating fluidized bed boilers were dispatched, to guide and advise for the operation of facilities introduced in these projects. The purpose of these projects is to diffuse the CCTs, and to support the promotion of environmental measures. Some guidance and advice about operation processes, data processing, operation regulation, maintenance, and boiler maintenance works were provided to the Ministry of Energy and Electric Power Corporation of the Philippines. Semirara, Malangas, and Samar coals in the Philippines were used for the tests. The boiler facilities could be operated by Philippine operators themselves. Based on the guidance and advice about operation processes, combustion tests using various Philippine coals were also planned and conducted by themselves. The maintenance techniques were transferred to Philippine operators through the inspection, repair and advice. The Philippine side understood the technologies well, and the circulating fluidized bed boiler technology was independently educated in the Philippines. 23 figs., 16 tabs.

  16. Fluidized-bed bioreactor system for the microbial solubilization of coal

    Science.gov (United States)

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

    1987-09-14

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

  17. Fluidized-bed bioreactor process for the microbial solubiliztion of coal

    Science.gov (United States)

    Scott, Charles D.; Strandberg, Gerald W.

    1989-01-01

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

  18. Anaerobic digestion of dairy wastewater by inverse fluidization: the inverse fluidized bed and the inverse turbulent bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Arnaiz, C.; Buffiere, P.; Elmaleh, S.; Lebrato, J.; Moletta, R.

    2003-11-01

    This paper describes the application of the inverse fluidization technology to the anaerobic digestion of dairy wastewater. Two reactors were investigated: the inverse fluidized bed reactor and the inverse turbulent reactor. In these reactors, a granular floating solid is expanded by a down-flow current of effluent or an up-flow current of gas, respectively. The carrier particles (Extendospheres) were chosen for their large specific surface area (20,000 m{sup 2} m{sup -3}) and their low energy requirements for fluidization (gas velocity of 1.5 mm s{sup -1}, 5.4 m h{sup -1}). Organic load was increased stepwise by reducing hydraulic retention time from more than 60 days to 3 days, while maintaining constant the feed COD concentration. Both reactors achieved more than 90% of COD removal, at an organic loading rate of 10-12 kg{sub COD} m{sup -3} d{sup -1}, respectively. The performances observed were similar or even higher than that of other previously tested fluidized bed technologies treating the same wastewater. It was found that the main advantages of this system are: low energy requirement, because of the low fluidization velocities required; there is no need of a settling device, because solids accumulate at the bottom of the reactor, so they can be easily drawn out and particles with high-biomass content can be easily recovered. Lipid phosphate concentration has been revealed as a good method for biomass estimation in biofilms since it only includes living biomass. (Author)

  19. Importance of fragmentation on the steady state combustion of wood char in a bubbling fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Pinho, Carlos [Universidade do Porto (CEFT/FEUP), Porto (Portugal). Faculdade de Engenharia. Centro de Estudos de Fenomenos de Transporte], E-mail: ctp@fe.up.pt

    2010-07-01

    A simple mathematical model for the analysis of the steady state behavior of a bubbling fluidized bed burner is presented, with the main intention of evaluating the importance of the primary fragmentation of fuel particles on the performance of this type of burners. This model has pedagogical advantages because of its simplicity and easiness of application to the analysis of realistic situations. The model is based upon the classical models used for the study of batch combustion processes in fluidized bed reactors. Experimental data from studies of fluidized bed combustion of portuguese vegetable chars are used to support the analysis of the performance of a 1 m diameter fluidized bed combustor. (author)

  20. Suspended solid abatement in a conical fluidized bed flocculator

    Institute of Scientific and Technical Information of China (English)

    Dandan ZHOU; Shuangshi DONG; Keyu LI; Huizhong JIANG; Dandan SHANG

    2013-01-01

    With the random movement of silica gel beads in a conical fluidized bed, micro-vortices resulting from the fluidization promoted the collision and aggregation of suspended fine kaolin powders. The abatement efficiencies of the suspended fine solids under several hydrodynamic conditions were studied, and a suitable control strategy for operating the conical fluidized bed flocculators was identified. The suspended solids abatement efficiency was found to increase with increasing Camp Number and flocculation time (T), but decreased with the increase of velocity gradient (G) within the range studied in this research (165.1-189.6s-1). The abatement efficiencies were all more than 60% at the range of G = 165-180 s 1 and T = 15-33 s at an initial kaolin solid concentration of 150mg·L-1, polymer aluminum chloride dosage of 60 mg· L -1 and sedimentation time of 20 min. However, the formation of flocs was influenced by the liquid back- mixing. Excessive backmixing caused the breakup of ftocs and resulted in difficulty for the fine powders to aggregate and sediment to the reactor bottom. The results of the calculated fractal dimension and measured free sedimenta- tion velocity of flocs obtained at different runs showed similar flocs properties, and indicated an easy control strategy for sedimentation of the flocs.

  1. Criteria for the fluidization hydrodynamical stability applied to a fluidized bed reactor; Criterio de estabilidade hidrodinamica de fluidizacao aplicada a um reator nuclear a leito fluidizado

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Volnei [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Escola de Engenharia

    1995-12-31

    A study of the bed behaviour in terms of the fluidization quality is presented for a fluidized bed nuclear reactor. The porosity of the transition from particulate to aggregate fluidization is evaluated. This study is necessary to determine the diameter of the fuel element and the range of porosity in which the fluidized bed is particulate, so as to obtain the representative unit cell of the system for the neutronic evaluations of this nuclear reactor. (author). 13 refs, 3 figs.

  2. Mass transfer in three-phase fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Wu, B.W.; Cheng, Y.L.; Perini, J.R.; Roux-Buisson, J.L.

    1978-04-26

    The effects of superficial liquid and gas velocity, particle diameter, liquid viscosity, and column diameter on liquid dispersion (E/sub L) and mass transfer (K/sub L/a) in three-phase fluidized beds were investigated using a water--glycerol/oxygen--nitrogen (or oxygen--argon)/glass-bead system. Overall mass transfer coefficients were calculated based on plug flow, dispersed plug flow, and continuously stirred tank models. k/sub L/a was found to increase with gas velocity and particle diameter, but no correlation of K/sub L/a with liquid velocity was observed. At low liquid velocities, K/sub L/a was lower for the more viscous liquid; the reverse was true at high liquid flow rates. E/sub L/ increased rapidly for liquid flow rates at two to three times the minimum fluidization velocity.

  3. 循环流化床高浓度富氧燃烧试验研究%Experimental Study on Oxy-fuel Combustion With High Oxygen Concentration in a Circulating Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    谭力; 李诗媛; 李伟; 寿恩广; 吕清刚

    2014-01-01

    In order to investigate the effects of combustion temperature and atmosphere on the combustion stability, CO2 concentration and gaseous pollutants emissions in flue gas, in a 0.1 MW circulating fluidized bed (CFB) oxy-fuel combustion facility, oxy-combustion experiments with Datong coal were carried out at O2/CO2 and O2/ recycled flue gas (RFG) atmosphere with high oxygen concentration. The test results show that when the oxygen concentration of the primary air ranges from 49.6%to 55.2%and that of the secondary air is in the range from 45.3%to 51.7%, the CFB oxy-fuel combustion facility maintains stably at O2/RFG atmosphere. In flue gas, CO2 concentration can reach above 90%, SO2 concentration is 87 to 197 mg/MJ, N2O concentration is 48 to 78 mg/MJ, and NO concentration is only 19 to 44 mg/MJ. Compared with the result of O2/CO2 combustion, the concentration of CO and SO2 increases to a certain degree, while N2O concentration decreases obviously, and NO concentration basically remains the same.%#在0.1 MW循环流化床富氧燃烧试验系统上,进行了大同烟煤在O2/再循环烟气(RFG)和O2/CO2配气下的高浓度富氧燃烧试验,研究燃烧温度和气氛对燃烧稳定性、烟气中CO2浓度和气体污染物排放的影响。研究结果表明,O2/RFG气氛下,在一次风氧气浓度为49.6%~55.2%、二次风氧气浓度为45.3%~51.7%范围内,循环流化床能够稳定运行,烟气中CO2浓度达到90%以上,SO2浓度为87~197 mg/MJ,N2O浓度为48~78 mg/MJ,NO仅为19~44 mg/MJ。与O2/CO2配气燃烧相比,O2/RFG燃烧时除NO浓度基本不变外,CO与SO2浓度均有一定程度的增加,而N2O浓度则明显降低。

  4. Direct Utilization of Circulating Fluidized Bed Combustion Ash of Distilled Spirits Lees as Fertilizer%白酒糟循环流化床燃烧灰直接肥料化利用

    Institute of Scientific and Technical Information of China (English)

    宋扬; 汪印; 姚常斌; 张玉明; 王昶; 易彬; 杨俊; 许光文

    2011-01-01

    研究了白酒糟循环流化床燃烧灰直接作为肥料的可能性和效果,以其为肥料种植油菜,考察了油菜在5种土壤中发芽和生长情况.结果表明,白酒糟燃烧灰对不同生长阶段的油菜有不同影响,对壤质土中的油菜发芽有抑制作用,但能明显改善粘性土壤中油菜的生长环境,油菜的净增量和产量都有明显增加.白酒糟燃烧灰还能提高酸性土壤pH值,使土壤环境向中性(pH 6.97~7.74)变,有利于腐殖酸分解和植物生长.土壤与白酒糟燃烧灰质量比为5:1时,与原土相比,泸州国窖红土壤、泸州青稞土壤及富阳土壤中油菜净增量分别为80.1%,80.9%,163.6%,表明利用白酒糟燃烧灰作为植物生长肥料是可行的.%The feasibility of utilizing the circulating fluidized bed combustion ash of distilled spirits lees as fertilizer was investigated. The rape culture experiment was carried out in 5 different kinds of soils, and the rape growth states in the germination and growth stages were measured to evaluate the effect of adding ash to the soils as fertilizer. The results show that the ash exhibited different effects on the rape growth in different culture stages. There was an antibiastic effect on the rape growth in the germination stage in a loamy soil, but the rape growth was much improved when adding the ash to a clayey soil. The latter led the mature rape to having obviously increased net height and weight. The ash could change the pH value of acid soil into neutral state, facilitating the humic acid decomposition and plant growth. Comparing the soils at soil:ash=5:l(ω) with original soil, the increased amplitudes of net height of rape in Guojiaohong Turang, Qingke Turang and Fuyang Turang were 80.1%, 80.9% and 163.6%, respectively. As consequence, it was feasible and effective to use directly the combustion ash of distilled spirits lees as fertilizer.

  5. NUMERICAL PREDICTION OF PARTICLE MIXING BEHAVIOR IN A BUBBLING FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    WU Chun-liang; ZHAN Jie-min

    2007-01-01

    In this article the hard-sphere Discrete Particle Model (DPM) is used to study the mixing behavior of particles in the 2-D fluidized bed. Different flow patterns in the bed for two kinds of inlet configurations, namely free bubbling and jet bubbling mode, are captured by the numerical model, under specific superficial gas velocities. To examine the degree of particle mixing, the Fan index is applied. The numerical results show that the rate of particle mixing is larger in the jet bubbling than that in the free bubbling mode. The gross circulations of particles in the jet bubbling bed give a higher degree of mixing because of the involvement of a greater number of particles.

  6. CFD simulation of fluidization quality in the three-dimensional fluidized bed

    Institute of Scientific and Technical Information of China (English)

    Kai Zhang; Stefano Brandani; Jicheng Bi; Jianchun Jiang

    2008-01-01

    Multiphase computational fluid dynamics (CFD) has become an alternative method to experimental investigation for predicting the fluid dynamics in gas-solid fluidized beds. The model of Brandani and Zhang, which contains additional terms in both the gas-and solid-phase momentum equations, is employed to explore homogeneous fluidization of Geldart type A particles and bubbling fluidizatiou Of Geldart type B particles in three-dimensional gas-fluidized beds. In this model, only a correlation for drag force is necessary to close the governing equations. Two kinds of solids, i. e., fine alumina powder (dp=60μm and ρp=1500kg/m3) and sand (dp=610μm and ρp=2500kg/m3), are numerically simulated in a rectangular duct of 0.2m (long)×0.2m (wide) ×0.5m (high) size. The results show good agreement with the classic theory of Geldart.

  7. An Experimental Investigation on the Drying of Sliced Food Products in Centrifugal Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    M.H.Shi; Y.L.Hao; 等

    1998-01-01

    An experimental investigation on the fluidization and drying characteristics of sliced food products in a centrifugal fluidized bed dryer was carried out,The rotaing speed ranges from 300 rpm to 500 rpm.Sliced potato and radish were used as the testing materials.The results show that the sliced materials can be fluidized well in the centrifugal fluidized bed.The fluidized curve has a maximum value and the critical fluidized velocities vary with the type of the test material,its shape and dimension as well as operating parameters.The sliced food materials can be dried very well and fast in the centrifugal fluidized bed with a large productivity.The factors that influence the drying process were examined and discussed.The final shape and inner structure of the dried products were observed.The water recovery characteristics of the drried products were also investigated.

  8. Research on coal staged conversion poly-generation system based on fluidized bed

    Institute of Scientific and Technical Information of China (English)

    Mingjiang Ni; Chao Li; Mengxiang Fang; Qinhui Wang; Zhongyang Luo; Kefa Cen

    2014-01-01

    A new coal staged conversion poly-generation system combined coal combustion and pyrolysis has been developed for clean and high efficient utilization of coal. Coal is the first pyrolysed in a fluidized pyrolyzer. The pyrolysis gas is then purified and used for chemical product or liquid fuel production. Tar is collected during purification and can be processed to extract high value product and to make liquid fuels by hydro-refining. Semi-coke from the pyrolysis reactor is burned in a circulating fluidized bed (CFB) combustor for heat or power generation. The system can realize coal multi-product generation and has a great potential to increase coal utilization value. A 1 MW poly-generation system pilot plant and a 12 MW CFB gas, tar, heat and power poly-generation system was erected. The experimental study focused on the two fluidized bed operation and characterization of gas, tar and char yields and compositions. The results showed that the system could operate stable, and produce about 0.12 m3/kg gas with 22 MJ/m3 heating value and about 10 wt%tar when using Huainan bituminous coal under pyrolysis temperature between 500 and 600 ?C. The produced gases were mainly H2, CH4, CO, CO2, C2H4, C2H6, C3H6 and C3H8. The CFB combustor can burn semi-coke steadily. The application prospect of the new system was discussed.

  9. ADVANCED SORBENT DEVELOPMENT PROGRAM DEVELOPMENT OF SORBENTS FOR MOVING-BED AND FLUIDIZED-BED APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    R.E Ayala; V.S. Venkataramani; Javad Abbasian; Rachid B. Slimane; Brett E. Williams; Minoo K. Zarnegar; James R. Wangerow; Andy H. Hill

    2000-03-31

    The integrated gasification combined cycle (IGCC) power system using high-temperature coal gas cleanup is one of the most promising advanced technologies for the production of electric power from coal in an environmentally acceptable manner. Unlike conventional low-temperature cleanup systems that require costly heat exchangers, high-temperature coal gas cleanup systems can be operated near 482-538 C (900-1000 F) or higher, conditions that are a closer match with the gasifier and turbine components in the IGCC system, thus resulting is a more efficient overall system. GE is developing a moving-bed, high-temperature desulfurization system for the IGCC power cycle in which zinc-based regenerable sorbents are currently being used as desulfurization sorbents. Zinc titanate and other proprietary zinc-based oxides are being considered as sorbents for use in the Clean Coal Technology Demonstration Program at Tampa Electric Co.'s (TECo) Polk Power Station. Under cold startup conditions at TECo, desulfurization and regeneration may be carried out at temperatures as low as 343 C (650 F), hence a versatile sorbent is desirable to perform over this wide temperature range. A key to success in the development of high-temperature desulfurization systems is the matching of sorbent properties for the selected process operating conditions, namely, sustainable desulfurization kinetics, high sulfur capacity, and mechanical durability over multiple cycles. Additionally, the sulfur species produced during regeneration of the sorbent must be in a form compatible with sulfur recovery systems, such as sulfuric acid or elemental sulfur processes. The overall objective of this program is to develop regenerable sorbents for hydrogen sulfide removal from coal-derived fuel gases in the temperature range 343-538 C (650-1000 F). Two categories of reactor configurations are being considered: moving-bed reactors and fluidized-bed (bubbling and circulating) reactors. In addition, a cost

  10. ADVANCED SORBENT DEVELOPMENT PROGRAM; DEVELOPMENT OF SORBENTS FOR MOVING-BED AND FLUIDIZED-BED APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    AYALA, R E; VENKATARAMANI, V S

    1998-09-30

    The integrated gasification combined cycle (IGCC) power system using high-temperature coal gas cleanup is one of the most promising advanced technologies for the production of electric power from coal in an environmentally acceptable manner. Unlike conventional low-temperature cleanup systems that require costly heat exchangers, high-temperature coal gas cleanup systems can be operated near 482-538 °C (900-1000 °F) or higher, conditions that are a closer match with the gasifier and turbine components in the IGCC system, thus resulting is a more efficient overall system. GE is developing a moving-bed, high-temperature desulfurization system for the IGCC power cycle in which zinc-based regenerable sorbents are currently being used as desulfurization sorbents. Zinc titanate and other proprietary zinc-based oxides are being considered as sorbents for use in the Clean Coal Technology Demonstration Program at Tampa Electric Co.'s (TECo) Polk Power Station. Under cold startup conditions at TECo, desulfurization and regeneration may be carried out at temperatures as low as 343 °C (650 °F), hence a versatile sorbent is desirable to perform over this wide temperature range. A key to success in the development of high-temperature desulfurization systems is the matching of sorbent properties for the selected process operating conditions, namely, sustainable desulfurization kinetics, high sulfur capacity, and mechanical durability over multiple cycles. Additionally, the sulfur species produced during regeneration of the sorbent must be in a form compatible with sulfur recovery systems, such as sulfuric acid or elemental sulfur processes. The overall objective of this program is to develop regenerable sorbents for hydrogen sulfide removal from coal-derived fuel gases in the temperature range 343-538 °C (650-1000 °F). Two categories of reactor configurations are being considered: moving-bed reactors and fluidized-bed (bubbling and circulating) reactors. In addition, a

  11. Enhanced Productivity of Chemical Processes Using Dense Fluidized Beds

    Energy Technology Data Exchange (ETDEWEB)

    Sibashis Banerjee; Alvin Chen; Rutton Patel; Dale Snider; Ken Williams; Timothy O' Hern; Paul Tortora

    2008-02-29

    The work detailed in this report addresses Enabling Technologies within Computational Technology by integrating a “breakthrough” particle-fluid computational technology into traditional Process Science and Engineering Technology. The work completed under this DOE project addresses five major development areas 1) gas chemistry in dense fluidized beds 2) thermal cracking of liquid film on solids producing gas products 3) liquid injection in a fluidized bed with particle-to-particle liquid film transport 4) solid-gas chemistry and 5) first level validation of models. Because of the nature of the research using tightly coupled solids and fluid phases with a Lagrangian description of the solids and continuum description of fluid, the work provides ground-breaking advances in reactor prediction capability. This capability has been tested against experimental data where available. The commercial product arising out of this work is called Barracuda and is suitable for a wide (dense-to-dilute) range of industrial scale gas-solid flows with and without reactions. Commercial applications include dense gas-solid beds, gasifiers, riser reactors and cyclones.

  12. The Physical Models of Cyclone Diplegs in Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    K.Smolders; D.Geldart; J.Baeyens

    2001-01-01

    In most industrial fluidization units, two- or three-stage cyclone systems are used to clean the product gases. To return the solids to the bed, these cyclones are fitted with diplegs. By pass of gas from the bed through the dipleg is partially overcome by the back pressure build-up in the dipleg and by adding a trickle valve at the bottom of the dipleg. Diplegs of primary cyclones, operating at a high solid loading behave differently from diplegs of secondary and tertiary cyclones which operate at low solid loading. Both types have been investigated by pressure drop measurements, visual observation and by measurements of the air flow rate flowing up the riser. The primary dipleg was also studied using electrical capacitance tomography. The results are reported hereafter and will give a first indication towards the right design of the dipleg and the selection of the trickle valve. The influence of gas flow in the dipleg on the conversion in a catalytic fluidized bed reactor is found to be negligible.

  13. Thermofluid effect on energy storage in fluidized bed reactor

    Science.gov (United States)

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

    2016-05-01

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

  14. Fluidized bed and method and system for gas component capture

    Energy Technology Data Exchange (ETDEWEB)

    Krutka, Holly; Wilson, Cody; Starns, Travis

    2016-05-31

    The present disclosure is directed to a process that allows dry sorbents to remove a target constituent, such as carbon dioxide (CO.sub.2), from a gas stream. A staged fluidized bed separator enables gas and sorbent to move in opposite directions. The sorbent is loaded with target constituent in the separator. It is then transferred to a regenerator where the target constituent is stripped. The temperature of the separator and regenerator are controlled. After it is removed from the regenerator, the sorbent is then transferred back to the separator.

  15. Standby cooling system for a fluidized bed boiler

    Science.gov (United States)

    Crispin, Larry G.; Weitzel, Paul S.

    1990-01-01

    A system for protecting components including the heat exchangers of a fluidized bed boiler against thermal mismatch. The system includes an injection tank containing an emergency supply of heated and pressurized feedwater. A heater is associated with the injection tank to maintain the temperature of the feedwater in the tank at or about the same temperature as that of the feedwater in the heat exchangers. A pressurized gas is supplied to the injection tank to cause feedwater to flow from the injection tank to the heat exchangers during thermal mismatch.

  16. Thermal energy storage systems using fluidized bed heat exchangers

    Science.gov (United States)

    Ramanathan, V.; Weast, T. E.; Ananth, K. P.

    1980-01-01

    The viability of using fluidized bed heat exchangers (FBHX) for thermal energy storage (TES) in applications with potential for waste heat recovery was investigated. Of the candidate applications screened, cement plant rotary kilns and steel plant electric arc furnaces were identified, via the chosen selection criteria, as having the best potential for successful use of FBHX/TES system. A computer model of the FBHX/TES systems was developed and the technical feasibility of the two selected applications was verified. Economic and tradeoff evaluations in progress for final optimization of the systems and selection of the most promising system for further concept validation are described.

  17. Dynamical simulation of fluidized beds - hydrodynamically interacting granular particles

    CERN Document Server

    Ichiki, K; Ichiki, Kengo; Hayakawa, Hisao

    1995-01-01

    A numerical simulation of a gas-fluidized bed is performed without introduction of any empirical parameters. Realistic bubbles and slugs are observed in our simulation. It is found that the convective motion of particles is important for the bubbling phase and there is no convection in the slugging phase. From the simulation results, non-Gaussian distributions are found in the particle velocities and the relation between the deviation from Gaussian and the local density of particles is suggested. It is also shown that the power spectra of particle velocities obey power laws. A brief explanation on the relationship between the simulation results and the Kolmogorov scaling argument is discussed.

  18. Agricultural uses of alkaline fluidized bed combustion ash: case studies

    Energy Technology Data Exchange (ETDEWEB)

    Stout, W.L.; Daily, M.R.; Nickeson, T.L.; Svendson, R.L.; Thompson, G.P. [USDA-ARS, University Park, PA (United States)

    1997-06-01

    Successful programmes were developed by Ahlstrom Development Ash Corporation and Air Products and Chemical for using fluidized bed combustion ash as a substitute for agricultural lime on dairy farms in northern New York state and on fruit and nut crops in the San Joaquin Valley of California. The companies developed these programmes by utilizing the methodology developed through USDA-ARS research and working closely with agricultural consultants and regulatory agencies to ensure that the ash applications were both agronomically and environmentally sound. 1 ref.

  19. Volatiles combustion in fluidized beds. [Quarterly] technical progress report, 4 December 1994--4 March 1995

    Energy Technology Data Exchange (ETDEWEB)

    Pendergrass II, R.A.; Mansker, L.D.; Hesketh, R.P.

    1995-08-01

    The goal of this project is to investigate the conditions in which volatiles will bum within both the dense and freeboard regions of fluidized beds. Experiments using a fluidized bed operated at incipient fluidization are being conducted to characterize the effect of particle surface area, initial fuel concentration, and particle type on the inhibition of volatiles within a fluidized bed. The work conducted during the period 4 December, 1994 through, 3 March 1995 is presented in this technical progress report. The research consists of the application of a detailed chemical kinetics model for propane combustion and planned improvements in the experimental system.

  20. Application of CaO-Based Bed Material for Dual Fluidized Bed Steam Biomass Gasification

    Science.gov (United States)

    Koppatz, S.; Pfeifer, C.; Kreuzeder, A.; Soukup, G.; Hofbauer, H.

    Gasification of biomass is a suitable option for decentralized energy supply based on renewable sources in the range of up to 50 MW fuel input. The paper presents the dual fluidized bed (DFB) steam gasification process, which is applied to generate high quality and nitrogen-free product gas. Essential part of the DFB process is the bed material used in the fluidized reactors, which has significant impact on the product gas quality. By the use of catalytically active bed materials the performance of the overall process is increased, since the bed material favors reactions of the steam gasification. In particular, tar reforming reactions are favored. Within the paper, the pilot plant based on the DFB process with 100kW fuel input at Vienna University of Technology, Austria is presented. Actual investigations with focus on CaO-based bed materials (limestone) as well as with natural olivine as bed material were carried out at the pilot plant. The application of CaO-based bed material shows mainly decreased tar content in the product gas in contrast to experiments with olivine as bed material. The paper presents the results of steam gasification experiments with limestone and olivine, whereby the product gas composition as well as the tar content and the tar composition are outlined.