Establishment of bubble-based EMMS/PFB model and its application on dense section of pressurized fluidized-bed

doi:10.11949/j.issn.0438-1157.20170230

Abstract

Abstract:

An energy minimization and multi-scale model, bubble-based EMMS/PFB, was established for pressurized fluidized-bed, based on methods of multi-scale decomposition and energy consumption analysis in combination with bubble diameter correlation to conical distributor. The model was used to simulate a 2D pressurized jetting fluidized-bed and to study influence of operating parameters such as operating pressure, bubble location, porosity and residual velocity on heterogeneous index. Comparison of simulation results to experimental data, it was showed that the new model provided better accuracy than the Gidaspow model in prediction of solid particle concentration distribution and change of particle velocity adjacent to wall above the distributor. Dense section simulation of a pressurized fluidized-bed by the new drag model yielded prediction of instantaneous and time-averaged axial distributions of particle concentration and particle velocity distribution. The simulation could make it available to visualize gas-solid flow behavior at dense section and provide guidance for design and industrial scale-up of pressurized fluidized-beds.

Key words: fluidized-bed, multi-scale, numerical simulation, bubble, two-phase flow, fluid dynamics

摘要：

基于多尺度分解和能量消耗分析方法，结合压力下锥形分布板射流床气泡直径关联式，建立了一个适于加压流化床（PFB）的能量最小多尺度模型——bubble-based EMMS/PFB模型。应用此模型模拟一个二维加压射流床，分析了操作压力、位置高度、空隙率及剩余速度对非均匀因子的影响。通过模拟结果与实验数据的对比，发现该模型相比于Gidaspow模型，能够更准确地模拟加压射流床内颗粒浓度的分布状态及颗粒靠近壁面处的速度变化；将这种曳力模型应用到流化床浓相段的模拟，预测了床内颗粒浓度瞬时分布及沿轴向的时均值分布、颗粒的速度分布等流动行为，使流化床浓相段的气固流动行为可视化，对流化床的设计、放大有一定的指导作用。

关键词: 流化床, 多尺度, 数值模拟, 气泡, 两相流, 流体动力学

CLC Number:

O359
TQ545

SONG Sufang, HAO Zhenhua, DONG Libo, LI Junguo, FANG Yitian. Establishment of bubble-based EMMS/PFB model and its application on dense section of pressurized fluidized-bed[J]. CIESC Journal, 2017, 68(8): 2998-3005.

宋素芳, 郝振华, 董立波, 李俊国, 房倚天. bubble-based EMMS/PFB模型的建立及在加压流化床浓相段的应用[J]. 化工学报, 2017, 68(8): 2998-3005.

References 30

[1]	LI J, KUIPERS J A M. Effect of pressure on gas-solid flow behavior in dense gas-fluidized beds:a discrete particle simulation study[J]. Powder Technology, 2002, 127:173-184.
[2]	OLOWSON P A, ALMSTEDT A E. Influence of pressure and fluidization velocity on the bubble behaviour and gas flow distribution in a fluidized bed[J]. Chemical Engineering Science, 1990, 45(7):1733-1741.
[3]	LI Z, ANNALAND M V S, KUIPERS J A M, et al. Effect of operating pressure on particle temperature distribution in a fluidized bed with heat production[J]. Chemical Engineering Science, 2016, 140:279-290.
[4]	NYOMAN S, WINAYA P B. Effect of pressure and carbon dioxide concentration on heat transfer at high temperature in a pressurized circulating fluidized bed (PCFB) combustor[J]. International Journal of Heat and Mass Transfer, 2001, 44:2965-2971.
[5]	CAO J T, CHENG Z H, FANG Y T. Simulation and experimental studies on fluidization properties in a pressurized jetting fluidized bed[J]. Powder Technology, 2008, 183(1):127-132.
[6]	VALIN S, RAVEL S, GUILLAUDEAU J. Comprehensive study of the influence of total pressure on products yields in fluidized bed gasification of wood sawdust[J]. Fuel Processing Technology, 2010, 91(10):1222-1228.
[7]	李俊国. 压力下射流流化床气固流动特性的研究[D]. 北京:中国科学院大学, 2013. LI J G. Hydrodynamic characteristics in jetting fluidized bed under pressure[D]. Beijing:University of Chinese Academy of Sciences, 2013.
[8]	WANG J W, ZHOU Q, HONG K. An EMMS-based multi-fluid model (EFM) for heterogeneous gas-solid riser flows(Ⅱ):An alternative formulation from dominant mechanisms[J]. Chemical Engineering Science, 2012, 75:349-358.
[9]	WANG W, LI J H. Simulation of gas-solid two-phase flow by a multi-scale CFD approach of the EMMS model to the sub-grid level[J]. Chemical Engineering Science, 2007, 62(1/2):208-231.
[10]	ZHOU Q, WANG J W. Coarse grid simulation of heterogeneous gas-solid flow in a CFB riser with EMMS drag model:effect of inputting drag correlations[J]. Powder Technology, 2014, 253:486-495.
[11]	LI J H, KWAUK M. Particle-Fluid Two Phase Flow:Energy-minimization Multi-scale Method[M]. Beijing:Metallurgical Industry Press, 1994.
[12]	YANG N, WANG W, GE W. Choosing structure-dependent drag coefficient in modeling gas-solid two-phase flow[J]. China Particuology, 2003, 1(1):38-41.
[13]	YANG N, WANG W, GE W. CFD simulation of concurrent-up gas-solid flow in circulating fluidized beds with structure-dependent drag coefficient[J]. Chemical Engineering Journal, 2003, 96(1/2/3):71-80.
[14]	ZENELI M, NIKOLOPOULOS A, NIKOLOPOULOS N. Application of an advanced coupled EMMS-TFM model to a pilot scale CFB carbonator[J]. Chemical Engineering Science, 2015, 138:482-498.
[15]	ZHAO M, ZHANG N, LIU X H. Numerical simulation of loop seal for a circulating fluidized bed based on an improved EMMS bubbling model[J]. Powder Technology, 2015, 284:443-451.
[16]	ZHOU Q, WANG J W. CFD study of mixing and segregation in CFB risers:extension of EMMS drag model to binary gas-solid flow[J]. Chemical Engineering Science, 2015, 122:637-651.
[17]	陈程, 祁海鹰. EMMS曳力模型及其颗粒团模型的构建和检验[J]. 化工学报, 2014, 65(6):2003-2012. CHEN C, QI H Y. Development and validation of cluster and EMMS drag model[J]. CIESC Journal, 2014, 65(6):2003-2012.
[18]	鲁波娜, 程从礼, 鲁维民. 基于多尺度模型的MIP提升管反应历程数值模拟[J]. 化工学报, 2013, 64(6):1983-1992. LU B N, CHENG C L, LU W M. Numerical simulation of reaction process in MIP riser[J]. CIESC Journal, 2013, 64(6):1983-1992.
[19]	王维, 洪坤, 鲁波娜. 流态化模拟:基于介尺度结构的多尺度CFD[J]. 化工学报, 2013, 64(1):95-106. WANG W, HONG K, LU B N. Fluidized bed simulation:structure-dependent multiscale CFD[J]. CIESC Journal, 2013, 64(1):95-106.
[20]	王雪瑶, 姜凡, 徐祥. 基于EMMS方法的曳力修正模型及实验验证[C]//中国工程热物理学会多项流2009年学术会议. 乌鲁木齐:中国工程热物理学会, 2009:1-7. WANG X Y, JIANG F, XU X. Modified drag model and experimental verification based on the EMMS method[C]//Proceedings of the Chinese Academy of Engineering Thermophysics 2009. Urumchi:CSET, 2009:1-7.
[21]	周泉, 王军武, 李静海, 基于EMMS的双流体模型及其在高密度循环流化床中的应用[C]//第七届全国流态化会议. 北京:流态化专业委员会, 2013:83-85. ZHOU Q, WANG J W, LI J H. EMMS-based two fluid model and its application to high-density circulating fluidized bed[C]//Proceedings of the 7th National Conference on Fluidization. Beijing:Fluidization Specialized Committee, 2013:83-85.
[22]	SHI Z S, WANG W, LI J H. A bubble-based EMMS model for gas-solid bubbling fluidization[J]. Chemical Engineering Science, 2011, 66(22):5541-5555.
[23]	CAI P, SCHIAVETTI M, MICHELE G D. Quantitative estimation of bubble size in PFBC[J]. Powder Technology, 1994, 80:99-109.
[24]	HORIO M, NONAKA A. A generalized bubble diameter correlation for gas-solid fluidized beds[J]. AIChE Journal, 1987, 33(11):1865-1872.
[25]	MORI S, WEN C Y. Estimation of bubble diameter in gaseous fluidized beds[J]. AIChE Journal, 1975, 21(1):109-115.
[26]	SONG S F, HAO Z H, DONG L B. A bubble-based EMMS model for pressurized fluidization and its validations with data of a jetting fluidized bed[J]. RSC Advances, 2016, 6:111041-111051.
[27]	THOMAS D G. Transport characteristics of suspension(Ⅷ):A note on the viscosity of Newtonian suspensions of uniform spherical particles[J]. Journal of Collioid Science, 1965, 20:267-277.
[28]	石战胜. 基于气泡的EMMS模型及其在煤气化炉CFD模拟中的应用[D]. 北京:中国科学院研究生院, 2011. SHI Z S. A bubble-based EMMS model for gas-solid fluidized beds and its application in CFD simulation of a coal gasifier[D]. Beijing:University of Chinese Academy of Sciences, 2011.
[29]	刘哲语, 李俊国, 李春玉. 多段分级转化流化床煤气化技术研发与进展[J]. 煤化工, 2016, (1):3-6. LIU Z Y, LI J G, LI C Y. Research and development of multi-stage conversion fluidized bed coal gasification technology[J]. Coal Chemical Industry, 2016, (1):3-6.
[30]	JOHNSON P C, JACKSON R. Frictional-collisional constitutive relations for granular materials, with application to plane shearing[J]. Journal of Fluid Mechanics, 1987, 176:67-93.