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full-loop simulation of Gas-Solids Flow in a Pilot-Scale Circulating Fluidized Bed

CHEMICAL ENGINEERING & TECHNOLOGY 2019年第4期42卷 932-939页

作者： Wang, Min Wu, Yingya Shi, Xiaogang Lan, Xingying Wang, Chengxiu Gao, Jinsen China Univ Petr State Key Lab Heavy Oil Proc Fuxue Rd 18 Beijing 102249 Peoples R China

In order to study the system hydrodynamics in a circulating fluidized bed (CFB), a 3D full-loop simulation was conducted for a pilot-scale CFB. The Eulerian-Eulerian two-fluid model with the kinetic theory of granular theory helped to simulate the gas-solids flow in the CFB. The system hydrodynamics including pressure balance, vectors of gas and solids, distribution of solids holdup, and instantaneous circulating rates were obtained to get a comprehensive understanding of the system. It was predicted that the main driving force was the pressure drop of the storage tank. The storage height and valve opening were critical operating factors to control the riser operation. The effects of operating conditions including solids circulating rates and superficial gas velocity on the hydrodynamics were investigated to provide guidance for the stable operation of the CFB system.

关键词： Circulating fluidized bed Computational fluid dynamics full-loop simulation Gas-solids flow Hydrodynamics

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3-D full-loop simulation of an Industrial-Scale Circulating Fluidized-Bed Boiler

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AICHE JOURNAL 2013年第4期59卷 1108-1117页

作者： Lu, Bona Zhang, Nan Wang, Wei Li, Jinghai Chiu, John H. Kang, Shin G. Chinese Acad Sci State Key Lab Multiphase Complex Syst Inst Proc Engn Beijing 100190 Peoples R China ALSTOM Power Inc Windsor CT 06095 USA

Three-dimensional (3-D) simulations using an Eulerian multiphase model were employed to explore flow behaviors in a full-loop industrial-scale CFB boiler with and without fluidized-bed heat exchanger (FBHE), where three solids phases were employed to roughly represent the polydisperse behavior of particles. First, a simulation of the boiler without FBHE is implemented to evaluate drag models, in terms of pressure profiles, mixing behaviors, radial velocity profiles, etc. Compared to the conventional model, the simulation using the energy-minimization multiscale (EMMS) model successfully predicts the pressure profile of the furnace. Then, such method is used to simulate the boiler with FBHE. The simulation shows that solid inventory in the furnace is underpredicted and reduced with an increase of the valve opening, probably due to the underevaluated drag for FBHE flows. It is suggested to improve EMMS model which is now based on a single set of operating parameters to match with the full-loop system. (C) 2012 American Institute of Chemical Engineers AIChE J, 59: 1108-1117, 2013

关键词： full-loop simulation multiscale boiler drag model polydisperse particles

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3D full-loop simulation of an industrial-scale circulating fluidized boiler

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7th International Symposium on Coal Combustion (ISCC)

作者： Lu, Bona Zhang, Nan Wang, Wei Li, Jinghai Chinese Acad Sci State Key Lab Multiphase Complex Syst Inst Proc Engn Beijing 100190 Peoples R China

ISBN: (纸本)9783642304446

In this study, 3D full-loop simulations of a CFB boiler are carried out. FLUENT (R) 6.3 is used as the solver, where an Eulerian multiphase model with EMMS-based drag model is employed. The wide particle size distribution are considered and divided into several groups to better represent the polydisperse behavior of ash particles. The simulation shows that, compared to the conventional drag model, EMMS-based model predicts more reasonable pressure drop of furnace and larger slip velocity at the lower elevations of the furnace. Further work is under way to improve the full-loop simulation.

关键词： full-loop simulation EMMS boiler drag model polydisperse particles

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Two-dimensional full-loop simulation of CO2 capture process in a novel dual fluidized bed system

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FUEL PROCESSING TECHNOLOGY 2020年 205卷 106429-106429页

作者： Shen, Yu Ma, Jiliang Liu, Daoyin Wu, Ying Zhong, Jian Chen, Xiaoping Wu, Ye Liang, Cai Southeast Univ Key Lab Energy Thermal Convers & Control Minist Educ Sch Energy & Environm Nanjing 210096 Peoples R China Nanjing Univ Sci & Technol MIIT Key Lab Thermal Control Elect Equipment Sch Energy & Power Engn Nanjing 210094 Peoples R China

The integrated bubbling-transport fluidized bed can realize both sufficient gas-solid contact time and adjustable solid circulation rate. This paper performed a full-loop simulation of continuous CO2 capture process in a dual fluidized-bed system, using the bubbling-transport bed as the adsorber and K2CO3/gamma-Al2O3 as the sorbents. Two-dimensional Eulerian-Eulerian models coupling with reaction kinetics were applied in the simulation. The results show that the adsorption reaction mainly takes place in the bubbling section of the adsorber, but rarely in the central riser and transport section. The increase of the sorbent circulation rate and the water vapor concentration in flue gas benefit the CO2 capture performance, and the latter is more preferable. Together with the sorbents, part of flue gas is entrained from the bubbling section to the central riser, causing an apparent fluctuation of sorbent circulation, as well as a low global CO2 capture efficiency due to the insufficient gas-sorbent contact.

关键词： CO2 capture K2CO3/Al2O3 full-loop simulation Fluidized bed

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Effect of process parameters on circulating fluidized bed coal gasification using 3D full-loop CFD simulation

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CANADIAN JOURNAL OF CHEMICAL ENGINEERING 2020年第8期98卷 1708-1728页

作者： Sharma, Vikrant Agarwal, Vijay K. Indian Inst Technol Roorkee Dept Chem Engn Roorkee 247667 Uttarakhand India

This article presents a 3D full-loop computational fluid dynamics (CFD) simulation of a circulating fluidized bed gasifier (CFBG). The simulation results are validated against the experimental data and found to be in good agreement. Thereupon, the effect of the process parameters, ie, temperature, pressure, air/coal (A/C) ratio, and steam/coal (S/C) ratio, on the performance of the gasifier is analyzed. The effect of temperature on the hydrodynamics was found to be small. The CO and H(2)increase, whereas the CO(2)and H2O decrease with an increase in temperature. While the effect of pressure on the outlet species mole fraction is negligible, the gas and solid axial velocity decrease with an increase in pressure. With an increasing A/C ratio or decreasing S/C ratio, the combustion products (CO(2)and H2O) increase, whereas the gasification products (CO and H-2) decrease due to the increase in the O(2)concentration. In addition, temperature increases with an increase in the A/C ratio or a decrease in the S/C ratio. The feed velocity increases with an increasing A/C or S/C ratio, and, accordingly, the pressure increases and bed height decreases. The CH(4)decreases in all of the cases as it is being consumed in gasification as well as combustion reactions.

关键词： CFB CFD full-loop simulation gasification process parameters

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Three-Dimensional full-loop Hydrodynamic simulation of a Circulating Fluidized-Bed Gasifier: A Quantitative Assessment of Drag Models

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ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2019年第12期44卷 9837-9850页

作者： Sharma, Vikrant Agarwal, Vijay Kumar Indian Inst Technol Roorkee Dept Chem Engn Roorkee 247667 Uttarakhand India

This article presents quantitative assessment of drag models based on their effect on hydrodynamics of a circulating fluidized bed (CFB). Three-dimensional full-loop computational fluid dynamics simulation using Euler granular multiphase model is carried out. Six drag models (EMMS, Gibilaro, Gidaspow, Schiller-Naumann, Syamlal-O'Brien and Wen-Yu) were employed, and simulated results of time-averaged solid volume fraction, solid axial velocity and static pressure are compared with the experimental data. Furthermore, a quantitative analysis is carried out using statistical parameters and parity plots. It was concluded that EMMS model is the most suitable model for simulation of a CFB as it is the only model capable of predicting heterogeneity of the bed, and simulation results agree well with the experimental data.

关键词： Circulating fluidized bed Computational fluid dynamics full-loop simulation Drag models Energy minimization multiscale model

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Numerical study on hydrodynamics of gas-solids circulating fluidized bed with L-valve

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Particuology 2023年第6期77卷 37-46页

作者： Hailun Ren Wenbin Li Liang Zeng Kunlei Liu Zhongli Tang Donghui Zhang Department of Chemical Engineering Tianjin Renai CollegeTianjin301636China School of Chemical Engineering and Technology Tianjin UniversityTianjin300072China Center for Applied Energy Research University of KentuckyLexingtonKY40511United States The Research Center of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072China

L-valve is often used as a non-mechanical valve for the circulation of solids in gas-solids fluidized bed(GSFB)due to its advantages in simple construction and easy *** information on solids circu-lation rate as well as the hydrodynamics performance of the CFB with L-valve is of great importance for its better control and *** paper proposes a Eulerian-Eulerian approach based numerical model integrating the computational fluid dynamics(CFD)with turbulent model,the kinetic theory of granular flow(KTGF)and the drag model,thus the solids circulation rate and the local phase velocity as well as solids volume fraction can be predicted *** this model,the hydrodynamics perfor-mance of the full loop GSCFB with a L-valve is analyzed in *** is found that the drag model affects the simulation significantly and the(energy minimization multiscale)EMMS method shows good per-formance in the full-loop simulation of GSCFB.

关键词： Gas-solids circulating fluidizedbed L-valve Computational fluid dynamics Drag model full-loop simulation

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Comparison of full-loop and riser-only simulations for a pilot-scale circulating fluidized bed riser

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CHEMICAL ENGINEERING SCIENCE 2014年 120卷 10-21页

作者： Li, Tingwen Dietiker, Jean-Francois Shadle, Lawrence Natl Energy Technol Lab Morgantown WV 26505 USA URS Corp Morgantown WV 26505 USA W Virginia Univ Corp Res Morgantown WV 26506 USA

In this paper, both full loop and riser only simulations of a pilot scale circulating fluidized bed (CFB) system carried out by the open source code MFIX (Multiphase Flow with Interphase eXchanges) are presented. Detailed comparison between full loop and riser only numerical simulations has been conducted with respect to the flow hydrodynamics inside the riser. The moan solids circulation rate is found to be the most critical parameter for both riser only and full loop simulations. On one hand, the mean solids circulation rate is needed for specifying the solids inlet boundary condition for the riser only simulation. On the other hand, a reasonable prediction of the solids circulation rate is a prerequisite for the full-loop simulation to properly predict the flow hydrodynamics inside the riser. To better account for the full-loop dynamics in the riser-only simulation, the transient solids circulation rate measured from an experimental facility is imposed in the simulation in addition to the mean solids circulation rate. Consistent numerical predictions of the flow hydrodynamics inside the riser are obtained by different types of simulations. In-depth discussion on the advantage and disadvantages of each approach is presented and the riser-only simulation with appropriate boundary conditions is shown to be sufficient for investigating the steady CFB riser flow. The full-loop simulation is promising but more challenging as all major components and associated complicated physics have to be included and correctly modeled which require both advanced model capability and high computer power. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Gas-solids flow Circulating fluidized bed Computational fluid dynamics full-loop simulation Flow hydrodynamics

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Numerical analysis of operating conditions for establishing high-density circulating fluidized bed by CPFD method

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POWDER TECHNOLOGY 2018年 338卷 446-457页

作者： Ma, Qiao Lei, Fulin Xiao, Yunhan Chinese Acad Sci Inst Engn Thermophys Key Lab Adv Energy & Power Beijing 100190 Peoples R China Chinese Acad Sci Res Ctr Clean Energy & Power Lianyungang 222069 Jiangsu Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Cent China Elect Power Test & Res Inst Co Ltd China Energy Engn Grp Changsha 410005 Hunan Peoples R China

The effects of operating conditions on the gas-solid hydrodynamics in a high-density CFB are numerically studied using the computational particle fluid dynamics approach. With the increase of standpipe bottom aeration rate, the solids circulation rate increases within the range of stable operation, while the packed bed height in the standpipe decreases. The same tendency is found for the standpipe aeration rate, however, it is more efficient than the bottom aeration rate to increase solids flux. With the increase of the solids inventory, the solids flux shows a parabolic relation with it, however, the standpipe pressure drop increases almost linearly under the fixed aeration conditions. The riser flowrate has only small effect on solids circulation behavior. The aeration distribution in the valve has little influence on solids flux, however, it affects significantly the valve pressure drop and transient flow behavior. The number of aeration ports on the standpipe does not influence solids flux much, but it affects the hydrodynamics stability of the standpipe. (C) 2018 Elsevier B.V. All rights reserved.

关键词： High-density CFB Standpipe aeration CPFD full-loop simulation

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A revised drag force model and the application for the gas-solid flow in the high-density circulating fluidized bed

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APPLIED THERMAL ENGINEERING 2011年第14-15期31卷 2254-2261页

作者： Wang, Xueyao Jiang, Fan Lei, Jing Wang, Jiachang Wang, Shengdian Xu, Xiang Xiao, Yunhan Chinese Acad Sci Inst Engn Thermophys Key Lab Adv Energy & Power Beijing 100190 Peoples R China Chinese Acad Sci Res Ctr Clean Energy & Power Lianyungang 222047 Peoples R China N China Elect Power Univ Sch Energy & Power Engn Beijing 102206 Peoples R China

The behavior of the gas-solid two-phase flow plays a vital role in the heat and mass transfer in the high-density circulating fluidized bed. In this paper, based on the energy-minimization multi-scale (EMMS) model, a drag force coefficient model, which can be applied to different kinds of particle, is developed for investigating the hydrodynamic characteristics of the high-density circulating fluidized bed (HDCFB). Coupled with the two-fluid model and the kinetic theory of granular, a 3D full-loop numerical simulation is implemented to test the validity of the revised drag force coefficient model, and excellent numerical performances and encouraging results are obtained. Under the operated conditions, the simulation results are in excellent agreement with the experimental data, which reveals that the revised drag force coefficient model is competent for the HDCFB's numerical simulation. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.

关键词： Gas-solid flow Drag force Energy-minimization multi-scale model full-loop simulation

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