Numerical investigation of bubbling fluidized bed with binary particle mixture using EMMS mesoscale drag model

doi:10.11949/j.issn.0438-1157.20190016

Abstract

Abstract:

Gas-solid bubbling fluidized beds have various industrial applications. The particles involved in practical applications usually display polydisperse characteristics (having different diameter or densities), resulting in segregation phenomena and consequently influencing flow hydrodynamics and reaction performance. Particle separation and mixing are inseparable from bubble motion, where interphase drag plays a key role. Recently, Ahmad et al. proposed a bubble-based mesoscale drag considering the effect of bidisperse features which is able to predict the bed expansion of binary bubbling fluidized beds. In this study, in order to investigate the applicability of the new drag model, two bubbling fluidized beds with different binary particle mixtures are simulated using the combination of the new drag model and the continuum model. Then, the bubble motion and axial profiles of jetsam volume ratio under two different fluidization states are mainly analyzed. It is found that the new drag model can predict well the particle segregation and mixing behaviors when the binary particles are fluidized completely. However, when the binary particles are fluidized at the transition state, the new drag model shows poor predictions, and the solid-solid drag plays a notable role in improving the prediction.

Key words: binary particle mixture, fluidized bed, mesocale, drag, CFD, EMMS

摘要：

双分散气固鼓泡流化床中颗粒通常具有不同粒径或密度，导致产生颗粒偏析等现象，影响传递和反应行为。颗粒分离和混合与气泡运动密不可分，其中相间曳力起关键作用。最近Ahmad等提出了一种基于气泡结构的双分散介尺度曳力模型，能成功预测双分散鼓泡流化床的床层膨胀系数。本研究耦合该曳力模型与连续介质方法，模拟了两种不同的双分散鼓泡流化床，通过分析不同流化状态下的气泡运动、颗粒浓度比的轴向分布等参数，进一步检验模型的适用性。研究表明，当双分散颗粒处于完全流化状态时，耦合双分散介尺度曳力模型可合理预测不同颗粒的分离现象；而其处于过渡流化状态时，新曳力模型和传统模型均无法获得合理结果，此时调节固固曳力可改进模拟结果。

关键词: 双分散颗粒, 流化床, 介尺度, 曳力, 计算流体力学, EMMS

CLC Number:

TONG Ying, AHMAD Nouman, LU Bona, WANG Wei. Numerical investigation of bubbling fluidized bed with binary particle mixture using EMMS mesoscale drag model[J]. CIESC Journal, 2019, 70(5): 1682-1692.

佟颖, Ahmad Nouman, 鲁波娜, 王维. 基于EMMS介尺度模型的双分散鼓泡流化床的模拟[J]. 化工学报, 2019, 70(5): 1682-1692.

Figures/Tables 13

Table 1 Material properties used in two systems of binary particle mixtures

参数	石英砂（silica sand）	玻璃珠（glass bead）	硅胶（silica gel）
系统1	√ (浮料)	√ (沉料)
系统2	√ (沉料)		√ (浮料)
Sauter平均粒径/μm	125	500	375
球形度	$≈$ 1	1	$≈$ 1
密度/(kg·m^-3)	2600	2540	600
Geldart分类	B	B	A-B
终端速度/(m·s^-1)	0.80	4.10	1.25
最小流态化速度/(m·s^-1)	0.022	0.23	0.032

Table 1 Material properties used in two systems of binary particle mixtures

参数	石英砂（silica sand）	玻璃珠（glass bead）	硅胶（silica gel）
系统1	√ (浮料)	√ (沉料)
系统2	√ (沉料)		√ (浮料)
Sauter平均粒径/μm	125	500	375
球形度	$≈$ 1	1	$≈$ 1
密度/(kg·m^-3)	2600	2540	600
Geldart分类	B	B	A-B
终端速度/(m·s^-1)	0.80	4.10	1.25
最小流态化速度/(m·s^-1)	0.022	0.23	0.032

Fig.1 Schematic diagram of simulated gas-solid fluidized beds (unit: m)

Table 2 Operating conditions for two systems of binary particle mixtures

操作参数	系统1	系统2
颗粒堆料量/kg	2.8	2.85
沉料的初始体积比 $X 20$	0.5	0.2
初始堆料高度/m	0.135	0.4
表观气速/(m·s^-1)	0.07,0.09	0.032,0.152

Table 2 Operating conditions for two systems of binary particle mixtures

操作参数	系统1	系统2
颗粒堆料量/kg	2.8	2.85
沉料的初始体积比 $X 20$	0.5	0.2
初始堆料高度/m	0.135	0.4
表观气速/(m·s^-1)	0.07,0.09	0.032,0.152

Table 3 Simulation settings

Parameter	Specification
transient formulation	second-order implicit
pressure-velocity coupling	phase coupled SIMPLE
gradient discretization	green-Gauss cell based
momentum discretization	second-order upwind
volume fraction discretization	quick
granular temperature	algebraic
granular viscosity	Syamlal-O’Brien
granular bulk viscosity	Lun-et-al
frictional viscosity	Schaeffer
angle of internal friction	30
frictional pressure	based-ktgf
frictional modulus	derived
friction packing limit	0.5
solid pressure	Lun-et-al
radial distribution	Ma-Ahmadi
elasticity modulus	derived
gas-solid drag	binary EMMS-bubbling or Gidaspow model
solid-solid interaction	Syamlal-O’Brien symmetric model
packing limit	0.62
restitution coefficient	0.9
physical time step	0.0001 s

Table 4 Average gas volume fraction and X 2 at height of 0.8 under three grid resolutions

网格尺寸	全床平均气含率	H=0.8对应的X ₂
5 mm ×5 mm	0.8063	0.4460
3 mm ×3 mm	0.8077	0.4572
2 mm ×2 mm	0.8081	0.4610

Fig.2 Evolution of distribution of gas holdup for system 1 (U g=0.09 m·s-1)

Fig.3 Distribution of gas holdup for systems 1 and 2 when reaching quasi-steady state using both gas-solid drag models

Fig.4 Evolution of distribution of solid volume fraction for system 1 (U g=0.09 m·s-1)

Fig.5 Axial profiles of volume ratio of jetsam fluidized completely

Fig.6 Axial profiles of volume ratio of jetsam fluidized at transition state

Fig.7 Axial profiles of volume ratio of jetsam (system 1: U g=0.07 m·s-1)

Fig.8 Comparison of axial profiles of volume ratio of jetsam using different gas-solid drag models(system 1: U g=0.07 m·s-1, K=0.005)

Fig.9 Axial profiles of volume ratio of jetsam (system 2: U g=0.032 m·s-1)

References 34

1	Formisani B , Girimonte R , Vivacqua V . Fluidization of mixtures of two solids: a unified model of the transition to the fluidized state[J]. AIChE Journal, 2013, 59(3):729-735.
2	Geldart D , Baeyens J , Pope D J , et al . Segregation in beds of large particles at high velocity[J]. Powder Technology, 1981, 30(2):195-205.
3	Grace J R , Sun G . Influence of particle size distribution on the performance of fluidized bed reactors[J]. The Canadian Journal of Chemical Engineering, 2010, 69(5): 1126-1134.
4	Hoffmann A C , Janssen L P B M , Prins J . Particle segregation in fluidised binary mixtures[J]. Chemical Engineering Science, 1993, 48(9): 1583-1592.
5	Lu H L , Gidaspow D . Hydrodynamics of binary fluidization in a riser: CFD simulation using two granular temperatures[J]. Chemical Engineering Science, 2003, 58(16):3777-3792.
6	Rowe P N . A preliminary quantitative study of particle segregation in gas fluidised beds-binary systems of near spherical particles[J]. Transactions of the Institution of Chemical Engineers, 1972, 50:324-333.
7	van Wachem B G M , Schouten J C , van den Bleek C M , et al . CFD modeling of gas-fluidized beds with a bimodal particle mixture[J]. AIChE Journal, 2001, 47(6):1292-1302.
8	Joseph G G , José L , Hrenya C M , et al . Experimental segregation profiles in bubbling gas fluidized bed[J]. AIChE Journal, 2007, 53(11):2804-2813.
9	Lu B , Wang W , Li J . Searching for a mesh-independent sub-grid model for CFD simulation of gas-solid riser flows[J]. Chemical Engineering Science, 2009, 64(15):3437-3447.
10	Wang W , Li J . Simulation of gas-solid two-phase flow by a multi-scale CFD approach -extension of the EMMS model to the sub-grid level[J]. Chemical Engineering Science, 2007, 62(1/2): 208-231.
11	Yang N , Wang W , Ge W , et al . CFD simulation of concurrent-up gas-solid flow in circulating fluidized beds with structure-dependent drag coefficient[J]. Chemical Engineering Journal, 2003, 96(8): 71-80.
12	Hong K , Shi Z , Wang W , et al . A structure-dependent multi-fluid model (SFM) for heterogeneous gas-solid flow[J]. Chemical Engineering Science, 2013, 99(9): 191-202.
13	Hong K , Shi Z , Ullah A , et al . Extending the bubble-based EMMS model to CFB riser simulations[J]. Powder Technology, 2014, 266(12): 424-432.
14	Chew J W , Hays R , Findlay J G , et al . Cluster characteristics of Geldart group B particles in a pilot-scale CFB riser (I): Monodisperse systems[J]. Chemical Engineering Science, 2012, 68(1):72-81.
15	Ahmad N , Tian Y , Lu B , et al . Extending the EMMS/bubbling model to fluidization of binary particle mixture: formulation and steady-state validation[J]. Chinese Journal of Chemical Engineering, 2019, 27(1): 54-62.
16	Ahmad N . Mesoscale modeling and CFD simulation of gas-fluidized bed with binary particle mixture [D]. Beijing: University of Chinese Academy of Sciences, 2018.
17	刘大有: 二相流体动力学[M]. 北京: 高等教育出版社, 1993.
	Liu D Y . Fluid Dynamics of Two-phase Systems [M]. Beijing: Higher Education Press, 1993.
18	Gidaspow D . Multiphase Flow and Fluidization: Continuum and Kinetic Theory Descriptions [M]. Boston: Academic Press, 1994.
19	Lungu M , Zhou Y , Wang J , et al . A CFD study of a bi-disperse gas-solid fluidized bed: effect of the EMMS sub grid drag correction[J]. Powder Technology, 2015, 280: 154-172.
20	Tagliaferri C , Mazzei L , Lettieri P , et al . CFD simulation of bubbling fluidized bidisperse mixtures: effect of integration methods and restitution coefficient[J]. Chemical Engineering Science, 2013, 102(3): 324-334.
21	Chao Z , Wang Y , Jakobsen J P , et al . Derivation and validation of a binary multi-fluid Eulerian model for fluidized beds[J]. Chemical Engineering Science, 2011, 66: 3605-3616.
22	Lu H L , Liu W T , Bie R S , et al . Kinetic theory of fluidized binary granular mixtures with unequal granular temperature[J]. Physica A: Statistical Mechanics and Its Applications, 2000, 284(1/2/3/4): 265-276.
23	Wen C Y , Yu Y H . Mechanics of fluidization[J]. Chemical Engineering Progress Symposium Series, 1966, 62(62): 100-111.
24	Gidaspow D . Hydrodynamics of fluidization and heat transfer: supercomputer modeling[J]. Applied Mechanics Reviews, 1986, 39(123): 1-22.
25	Ergun S . Fluid flow through packed columns[J]. Chemical Engineering and Processing, 1952, 48(2): 89-94.
26	Bell R A . Numerical modelling of multi-particle flows in bubbling gas-solid fluidised beds [D]. Melbourne: Swinburne University of Technology, 2000.
27	Arastoopour H , Wang C H , Weil S A . Particle-particle interaction force in a dilute gas-solid system[J]. Chemical Engineering Science, 1982, 37(9): 1379-1386.
28	Syamlal M . Multiphase hydrodynamics of gas-solid flow[D]. Chicago: Illinois Institute of Technology, 1985.
29	Gidaspow D , Ding J , Jayaswal U K . Multiphase Navier-Stokes equation solver[C]// Numerical Methods for Multiphase Flow. ASME, New York, 1990, 91: 47-56.
30	Chao Z , Wang Y , Jakobsen J P , et al . Investigation of the particle-particle drag in a dense binary fluidized bed[J]. Powder Technology, 2012, 224: 311-322.
31	Syamlal M . The particle-particle drag term in a multiparticle model of fluidization[R]. National Technical information service, Springfield, VA. DOE/MC/21353-2373, NTIS/DE87006500, 1987.
32	Marzocchella A , Salatino P , Pastena V D , et al . Transient fluidization and segregation of binary mixtures of particles[J]. AIChE Journal, 2000, 46(11): 2175-2182.
33	Olivieri G , Marzocchella A , Salatino P . Segregation of fluidized binary mixtures of granular solids[J]. AIChE Journal, 2004, 50(12): 3095-3106.
34	Li T , Pannala S , Shahnam M . CFD simulations of circulating fluidized bed risers (Ⅱ): Evaluation of differences between 2D and 3D simulations[J]. Powder Technology, 2014, 265: 13-22.

[1]	Song HE, Qiaomai LIU, Guangshuo XIE, Simin WANG, Juan XIAO. Two-phase flow simulation and surrogate-assisted optimization of gas film drag reduction in high-concentration coal-water slurry pipeline [J]. CIESC Journal, 2023, 74(9): 3766-3774.
[2]	Kaijie WEN, Li GUO, Zhaojie XIA, Jianhua CHEN. A rapid simulation method of gas-solid flow by coupling CFD and deep learning [J]. CIESC Journal, 2023, 74(9): 3775-3785.
[3]	Dian LIN, Guomei JIANG, Xiubin XU, Bo ZHAO, Dongmei LIU, Xu WU. Preparation and drag reduction effect of silicon-based liquid-like anti-crude-oil-adhesion coatings [J]. CIESC Journal, 2023, 74(8): 3438-3445.
[4]	Chao NIU, Shengqiang SHEN, Yan YANG, Bonian PAN, Yiqiao LI. Flow process calculation and performance analysis of methane BOG ejector [J]. CIESC Journal, 2023, 74(7): 2858-2868.
[5]	Yuying GUO, Jiaqiang JING, Wanni HUANG, Ping ZHANG, Jie SUN, Yu ZHU, Junxuan FENG, Hongjiang LU. Water-lubricated drag reduction and pressure drop model modification for heavy oil pipeline [J]. CIESC Journal, 2023, 74(7): 2898-2907.
[6]	Zhenghao YANG, Zhen HE, Yulong CHANG, Ziheng JIN, Xia JIANG. Research progress in downer fluidized bed reactor for biomass fast pyrolysis [J]. CIESC Journal, 2023, 74(6): 2249-2263.
[7]	Juhui CHEN, Qian ZHANG, Lingfeng SHU, Dan LI, Xin XU, Xiaogang LIU, Chenxi ZHAO, Xifeng CAO. Study on flow characteristics of nanoparticles in a rotating fluidized bed based on DEM method [J]. CIESC Journal, 2023, 74(6): 2374-2381.
[8]	Yuanyuan ZHANG, Jiangyuan QU, Xinxin SU, Jing YANG, Kai ZHANG. Gas-liquid mass transfer and reaction characteristics of SNCR denitration in CFB coal-fired unit [J]. CIESC Journal, 2023, 74(6): 2404-2415.
[9]	Daoyin LIU, Bingqi CHEN, Zuyang ZHANG, Yan WU. Effect of agglomerate structure on drag force by numerical simulation [J]. CIESC Journal, 2023, 74(6): 2351-2362.
[10]	Xin DONG, Yongrui SHAN, Yinuo LIU, Ying FENG, Jianwei ZHANG. Numerical simulation of bubble plume vortex characteristics for non-Newtonian fluids [J]. CIESC Journal, 2023, 74(5): 1950-1964.
[11]	Zihan YUAN, Shuyan WANG, Baoli SHAO, Lei XIE, Xi CHEN, Yimei MA. Investigation on flow characteristics of wet particles with power-law liquid-solid drag models in fluidized bed [J]. CIESC Journal, 2023, 74(5): 2000-2012.
[12]	Airan ZHOU, Ping LU, Jianhui XIA, Dongqin LI, Jie GUO, Ming DU, Lichun DONG. Scarring analysis and numerical simulation of TiCl₄ oxidation reactor in chloride process of titanium dioxide [J]. CIESC Journal, 2023, 74(4): 1499-1508.
[13]	Jinsheng REN, Kerun LIU, Zhiwei JIAO, Jiaxiang LIU, Yuan YU. Research on the mechanism of disaggregation of particle aggregates near the guide vanes of turbo air classifier [J]. CIESC Journal, 2023, 74(4): 1528-1538.
[14]	Weizheng ZHANG, Jijun ZHAO, Xuezhong MA, Qixuan ZHANG, Yixiang PANG, Juntao ZHANG. Analysis of turbulence effect on face groove cooling performance of high-speed mechanical seals [J]. CIESC Journal, 2023, 74(3): 1228-1238.
[15]	Longfei JIA, Shaotong FU, Xing XIANG, Huahai ZHANG, Tao ZHANG, Limin WANG. Lattice Boltzmann simulations of the effect of particles movement on momentum transfer process [J]. CIESC Journal, 2023, 74(2): 735-747.