CFD simulation of particle flow in new type of gas-solid air loop reactor

doi:10.11949/j.issn.0438-1157.20160388

Abstract

Abstract:

The behavior of particle flow in a new type of gas-solid air loop reactor (GSALR), which acted as a particle mixer, was numerically simulated by multi-scale computational fluid dynamics (CFD) with the structure-dependent EMMS drag model. The suitability of the drag model was verified by agreement of the simulated results and the experimental data in time averages of solid holdup and particle velocity. The particle upward velocity increased but the mean solid holdup on beds decreased when the superficial gas velocity increased in the draft tube. Several mixing regions of particle crossflow and mixed flow in GSALR improved the efficiency of radial particle mixing. In the groove region, the distributions of solid holdup and particle velocity were more uniform, while a particle concentrating area was formed at circular overlap due to particle flow from the groove. In the region of 0≤L≤0.058 m and 0< r/R< 0.3, the solid holdup was increased and particle flow was evidently enhanced along the radial direction.

Key words: CFD, circulating fluidized bed, multi-scale, particle flow, gas-solid two phase

摘要：

采用基于结构的EMMS曳力模型，对一种新型气固环流反应器中的颗粒流动特性进行数值模拟。模拟的固含率与颗粒速率预测值与实验数据具有一致性，验证了模型的适用性。模拟结果表明：导流筒表观气速增加，导流筒中的床层固含率减小，向上的颗粒速率增加；反应器中存在多个颗粒逆流和错流混合区，促进了颗粒沿径向的混合；槽孔处，导流筒中的固含率以及颗粒速率分布更加均匀，而环隙中存在颗粒浓集区；进料区在0≤L≤0.058 m，0< r/R< 0.3的范围内固含率增加并且颗粒存在明显的径向流动。

关键词: 计算流体力学, 循环流化床, 多尺度, 颗粒流动, 气固两相

CLC Number:

TQ052.5

MENG Zhenliang, LIU Mengxi, LI Fei, WANG Wei, LU Chunxi. CFD simulation of particle flow in new type of gas-solid air loop reactor[J]. CIESC Journal, 2016, 67(8): 3234-3243.

孟振亮, 刘梦溪, 李飞, 王维, 卢春喜. 新型气固环流反应器内颗粒流动的CFD模拟[J]. 化工学报, 2016, 67(8): 3234-3243.

References 22

[1]	丁富新,李飞,袁乃驹.环流反应器的发展和应用[J].石油化工,2004,33(9):801-807.DING F X,LI F,YUAN N J.Application and development of air loop reactor[J].Petrochemical Technology,2004,33(9):801-807.
[2]	刘梦溪,卢春喜,时铭显.气固环流反应器的研究进展[J].化工学报,2013,64(1):116-123.LIU M X,LU C X,SHI M X.Advances in gas-solids airlift loop reactor[J].CIESC Journal,2013,64(1):116-123.
[3]	WEN J P,NA P,HUANG L,et al.Local overall gas-liquid mass transfer coefficient in a gas-liquid-solid reversed flow jet loop reactor[J].Chemical Engineering Journal,2002,88:209-213.
[4]	MUDDE R F,VAN DEN AKKER H E A.2D and 3D simulations of an internal airlift loop reactor on the basis of a two-fluid model[J].Chem.Eng.Sci.,2001,56(21/22):6351-6358.
[5]	刘梦溪,谢建平,卢春喜,等.环隙气升式气固环流反应器内流体力学特性的理论分析[J].化工学报,2008,59(9):2198-2205.LIU M X,XIE J P,LU C X,et al.Theoretical analysis of hydrodynamics in novel gas-solids annulus-sparged airlift loop reactor[J].Journal of Chemical Industry and Engineering (China),2008,59(9):2198-2205.
[6]	沈志远,杨利军,刘梦溪,等.中心气升式气-固环流反应器中床层密度的实验研究[J].中国粉体技术,2012,18(1):66-71.SHEN Z Y,YANG L J,LIU M X,et al.Experimental study on bed density distribution in a novel draft tube-lifted gas-solid air loop reactor[J].China Powder Science and Technology,2012,18(1):66-71.
[7]	严超宇,卢春喜,王德武,等.气固环流反应器内瞬态流体力学特性的数值模拟[J].化工学报,2010,61(9):2225-2234.YAN C Y,LU C X,WAND D W,et al.Numerical simulation of transient hydrodynamics in gas-solid airlift loop reactor[J].CIESC Journal,2010,61(9):2225-2234.
[8]	KIM S D,KIM Y H,ROH S A,et al.Solid circulation characteristics in an internally circulating fluidized bed with orifice-type draft tube[J].Korean J.Chem.Eng.,2002,19:911-916.
[9]	刘梦溪,牛占川,卢春喜,等.导流筒分布器位置对环隙气升式气固环流反应器流体力学性能的影响[J].化工学报,2010,61(9):2250-2256.LIU M X,NIU Z C,LU C X,et al.Effect of draft tube gas distributor on hydrodynamics in an annulus-lifted gas-solid air loop reactor[J].CIESC Journal,2010,61(9):2250-2256.
[10]	严超宇,卢春喜.气固环流燃烧器内颗粒流动行为[J].化工学报,2010,61(6):1357-1366.YAN C Y,LU C X.Fluidization behavior in gas-solid air lift loop combustor[J].CIESC Journal,2010,61(6):1357-1366.
[11]	卢春喜.环流技术在石油炼制领域中的研究与应用[J].化工学报,2010,61(9):2177-2185.LU C X.Research and industry application of loop flow technology in the field of petroleum processing[J].CIESC Journal,2010,61(9):2177-2185.
[12]	LIU M X,XIE J M,MENG Z L,et al.Hydrodynamic characteristics and mixing characteristics of a new type particle mixer[J].Journal of Chemical Engineering of Japan,2015,48(7):564-574.
[13]	WANG W,LI J H.Simulation of gas-solid two-phase flow by a multi-scale CFD approach-extension of the EMMS model to the sub-grid level[J].Chem.Eng.Sci.,2007,62:208-231.
[14]	SHI Z S,WANG W,LI J H.A bubble-based EMMS model for gas-solid bubbling fluidization[J].Chem.Eng.Sci.,2011,66:5541-5555.
[15]	HONG K,SHI Z S,WANG W,et al.A structure-dependent multi-fluid model (SFM) for heterogeneous gas-solid flow[J].Chem.Eng.Sci.,2013,99:191-202.
[16]	GIDASPOW D.Multiphase Flow and Fluidization:Continuum and Kinetic Theory Description[M].Boston:Academic Press,1994.
[17]	SINCLAIR J L,JACKSON R.Gas-particle flow in a vertical pipe with particle-particle interactions[J].AIChE Journal,1989,35:1473-1496.
[18]	李静海.颗粒流体两相流:能量最小多尺度模型[M].北京:冶金工业出版社,1994.LI J H.Particle-fluid Two-phase Flow:Energy-Minimization Multi-Scale Method[M].Beijing:Metallurgy Industry Press,1994.
[19]	ERGUN S.Fluid flow through packed columns[J].Chemical Engineering Process,1952,48(2):89-94.
[20]	WEN C Y,YU Y H.Mechanics of fluidization[J].Chemical Engineering Symposium Series,1966,62(62):100-111.
[21]	LI T,BENYAHIA S.Evaluation of wall boundary condition parameters for gas-solids fluidized bed simulations[J].AIChE Journal,2013,59(10):3624-3632.
[22]	LI T,BENYAHIA S.Revisiting Johnson and Jackson boundary conditions for granular flows[J].AIChE Journal,2012,58(7):2058-2068.