提升管内颗粒介尺度流动特性研究

doi:10.11949/0438-1157.20251085

摘要/Abstract

摘要：

气固流化床中，介于颗粒尺度与宏观尺度间的介尺度结构（颗粒聚团）的存在会改变气固相间作用规律，显著影响流化性能。本文将固相介尺度应力视为由颗粒聚团引起的附加应力，采用过滤方法，建立介尺度应力与聚团直径和聚团拟温度的关联。采用过滤双流体模型模拟提升管中的气固流动行为，获得了提升管内颗粒聚团的介尺度特性。模拟结果表明：固相应力包括介尺度应力和颗粒尺度应力，且介尺度应力约为颗粒尺度应力的两倍；聚团尺度的脉动强度远低于颗粒尺度；聚团直径在颗粒浓度约为0.05时达到最大值，并随气体速度的增加而增大。

关键词: 过滤双流体模型, 介尺度, 上升管, 固相应力, 数值模拟

Abstract:

In gas-solid fluidized beds, the presence of mesoscale flow structures alters gas-solid interphase interactions and substantially impact fluidized performance. In the present study, the mesoscale stress component of the solid stress constitutes an additional contribution arising from the cluster scale, and the correlations regarding of mesoscale stress, cluster diameter, and cluster-scale granular temperature are established based on filtered method. The filtered two-fluid model is employed to simulate the gas-solid flow behavior in the riser, meanwhile the mesoscale flow characteristics of clusters are obtained. The simulated results indicate that solid stress comprises both mesoscale stress and microscale stress contributions, with the mesoscale stress being approximately twice that of the microscale stress. Cluster-scale fluctuations are significantly weaker than particle-scale fluctuations. Cluster diameter peak appears at the location of a particle concentration of approximately 0.05 and increases with rising gas velocity.

Key words: Filtered two-fluid model, mesoscale, riser, solid stress, numerical simulation

中图分类号:

TQ 018

丁诺, 王淑彦, 邵宝力, 陈曦, 陈华. 提升管内颗粒介尺度流动特性研究[J]. 化工学报, DOI: 10.11949/0438-1157.20251085.

Nuo DING, Shuyan WANG, Baoli SHAO, Xi CHEN, Hua CHEN. Research on mesoscale flow characteristics of particles in a riser[J]. CIESC Journal, DOI: 10.11949/0438-1157.20251085.

图/表 12

图1 试验设备和提升管结构示意图

Fig.1 Structure scheme of experiment facility and riser

表1 提升管模拟参数

Table 1 Simulated parameters of riser

参数	实验	模拟
提升管高度(m)	7.6	7.6
提升管宽(m)	0.114	0.114
提升管深度(m)	0.019	0.019
气体密度(kg/m³)		1.225
气体黏度(Pa·s)		1.78948×10^-5
气体进口速度(m/s)	5.0、5.5	5.0、5.5
颗粒密度(kg/m³)	1877	1877
颗粒直径(m)	6.7×10^-5	6.7×10^-5
颗粒入口浓度		20%
颗粒质量流速(kg/m²s)	100、150、200	100、150、200
恢复系数		0.9

图2 提升管颗粒浓度径向和轴向分布与实验值对比

Fig.2 Comparisons of simulated particle concentration radial and axial distribution with experimental data

表2 聚团直径与颗粒浓度的关联式

Table 2 Correlation between cluster diameter and particle volume fraction

作者	关联式
Harris等^[32]	$d c l = ε s 40.8 - 94.5 ε s$
Gu^[33]	$d c l = d s + (0.027 - 10 d s) ε s + 32 ε s 6$
Subbarao^[34]	$d c l = d s + ε s ε s - ε g c 1 / 3 2 u t 2 ¯ g 1 + u t 2 ¯ (0.35 g D) 2 - 1$

表2 聚团直径与颗粒浓度的关联式

Table 2 Correlation between cluster diameter and particle volume fraction

作者	关联式
Harris等^[32]	$d c l = ε s 40.8 - 94.5 ε s$
Gu^[33]	$d c l = d s + (0.027 - 10 d s) ε s + 32 ε s 6$
Subbarao^[34]	$d c l = d s + ε s ε s - ε g c 1 / 3 2 u t 2 ¯ g 1 + u t 2 ¯ (0.35 g D) 2 - 1$

图3 提升管充分发展段颗粒浓度和聚团直径与实验值的对比

Fig.3 Comparison of particle concentration and cluster diameter in the fully developed region with experimental data

图4 固相应力和碰撞能量耗散随颗粒浓度变化

Fig.4 Solid stress and collision energy dissipation of particles as a function of particle concentration

图5 总颗粒压力和总颗粒黏度在壁面区域和中心区域的变化

Fig.5 Variation of total granular pressure and total granular viscosity near the wall and in the center

图6 聚团直径和相间滑移速度随颗粒浓度变化

Fig.6 Cluster diameter and interphase slip velocity as a function of particle concentration

图7 气体速度对提升管颗粒浓度轴向分布的影响

Fig.7 Effects of gas velocity on axial distribution of the particle concentration

图8 气体速度对固相应力和颗粒碰撞能量耗散的影响

Fig. 8 Effects of gas velocity on solid stress and collision energy dissipation of particles

图9 气体速度对颗粒拟温度和聚团拟温度的影响

Fig. 9 Effects of gas velocity on granular temperature and cluster-scale granular temperature

图10 气体速度对聚团直径的影响

Fig. 10 Effects of gas velocity on cluster diameter

参考文献 34

[1]	Zhang H, Huang W X, Zhu J X. Gas-solids flow behavior: CFB riser vs. downer[J]. AIChE Journal, 2001, 47(9): 2000-2011.
[2]	王成秀, 裴华健, 苏鑫, 等. 密相提升管内颗粒速度与颗粒浓度分布及发展特性[J]. 化学反应工程与工艺, 2020, 36(1): 8-16.
	Wang C X, Pei H J, Su X, et al. Particle velocity and solids holdup characteristics and the flow development in a high density circulating fluidized bed riser[J]. Chemical Reaction Engineering and Technology, 2020, 36(1): 8-16.
[3]	Tian P, Wei Y X, Ye M, et al. Methanol to olefins (MTO): from fundamentals to commercialization[J]. ACS Catalysis, 2015, 5(3): 1922-1938.
[4]	Fullmer W D, Hrenya C M. The clustering instability in rapid granular and gas-solid flows[J]. Annual Review of Fluid Mechanics, 2017, 49: 485-510.
[5]	葛蔚, 刘新华, 任瑛, 等. 从多尺度到介尺度: 复杂化工过程模拟的新挑战[J]. 化工学报, 2010, 61(7): 1613-1620.
	Ge W, Liu X H, Ren Y, et al. From multi-scale to meso-scale: new challenges for simulation of complex processes in chemical engineering[J]. CIESC Journal, 2010, 61(7): 1613-1620.
[6]	Manyele S V, Pärssinen J H, Zhu J X. Characterizing particle aggregates in a high-density and high-flux CFB riser[J]. Chemical Engineering Journal, 2002, 88(1/2/3): 151-161.
[7]	Cocco R, Shaffer F, Hays R, et al. Particle clusters in and above fluidized beds[J]. Powder Technology, 2010, 203(1): 3-11.
[8]	Wang J W, Ge W, Li J H. Eulerian simulation of heterogeneous gas–solid flows in CFB risers: EMMS-based sub-grid scale model with a revised cluster description[J]. Chemical Engineering Science, 2008, 63(6): 1553-1571.
[9]	Sundaresan S, Ozel A, Kolehmainen J. Toward constitutive models for momentum, species, and energy transport in gas-particle flows[J]. Annual Review of Chemical and Biomolecular Engineering, 2018, 9: 61-81.
[10]	Lu B N, Wang W, Li J H. Eulerian simulation of gas–solid flows with particles of Geldart groups A, B and D using EMMS-based meso-scale model[J]. Chemical Engineering Science, 2011, 66(20): 4624-4635.
[11]	Yin W J, Wang S, Gao G H, et al. A cluster-based drag model of rough sphere for the simulation of fast fluidization[J]. Chemical Engineering Research and Design, 2022, 187: 451-460.
[12]	Wen C Y, Yu Y H. Mechanics of fluidization[J]. Chemical Engineering Progress Symposium Series, 1966, 62: 100-111.
[13]	Neri A, Gidaspow D. Riser hydrodynamics: Simulation using kinetic theory[J]. AIChE Journal, 2000, 46(1): 52-67.
[14]	Lu H L, Gidaspow D, Bouillard J, et al. Hydrodynamic simulation of gas–solid flow in a riser using kinetic theory of granular flow[J]. Chemical Engineering Journal, 2003, 95(1/2/3): 1-13.
[15]	Agrawal K, Loezos P N, Syamlal M, et al. The role of meso-scale structures in rapid gas–solid flows[J]. Journal of Fluid Mechanics, 2001, 445: 151-185.
[16]	Ozel A, Fede P, Simonin O. Development of filtered Euler–Euler two-phase model for circulating fluidised bed: High resolution simulation, formulation and a priori analyses[J]. International Journal of Multiphase Flow, 2013, 55: 43-63.
[17]	Jiradilok V, Gidaspow D, Damronglerd S, et al. Kinetic theory based CFD simulation of turbulent fluidization of FCC particles in a riser[J]. Chemical Engineering Science, 2006, 61(17): 5544-5559.
[18]	Benyahia S, Sundaresan S. Do we need sub-grid scale corrections for both continuum and discrete gas-particle flow models?[J]. Powder Technology, 2012, 220: 2-6.
[19]	Li J H, Kwauk M. Particle-fluid Two-phase Flow: the Energy-Minimization Multi-scale Method[M]. Beijing: Metallurgical Industry Press, 1994.
[20]	Wang J W. Continuum theory for dense gas-solid flow: a state-of-the-art review[J]. Chemical Engineering Science, 2020, 215: 115428.
[21]	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.
[22]	Jiang Y, Li F, Ge W, et al. EMMS-based solid stress model for the multiphase particle-in-cell method[J]. Powder Technology, 2020, 360: 1377-1387.
[23]	He M M, Zhao B D, Wang J W. A unified EMMS-based constitutive law for heterogeneous gas-solid flow in CFB risers[J]. Chemical Engineering Science, 2020, 225: 115797.
[24]	Igci Y, Andrews IV A T, Sundaresan S, et al. Filtered two-fluid models for fluidized gas-particle suspensions[J]. AIChE Journal, 2008, 54(6): 1431-1448.
[25]	Igci Y, Pannala S, Benyahia S, et al. Validation studies on filtered model equations for gas-particle flows in risers[J]. Industrial & Engineering Chemistry Research, 2012, 51(4): 2094-2103.
[26]	Milioli C C, Milioli F E. On the subgrid behavior of accelerated riser flows for a high stokes number particulate[J]. Industrial & Engineering Chemistry Research, 2011, 50(23): 13538-13544.
[27]	Sarkar A, Milioli F E, Ozarkar S, et al. Filtered sub-grid constitutive models for fluidized gas-particle flows constructed from 3-D simulations[J]. Chemical Engineering Science, 2016, 152: 443-456.
[28]	Cloete J H, Cloete S, Municchi F, et al. Development and verification of anisotropic drag closures for filtered Two Fluid Models[J]. Chemical Engineering Science, 2018, 192: 930-954.
[29]	Xu J, Zhu J X. Experimental study on solids concentration distribution in a two-dimensional circulating fluidized bed[J]. Chemical Engineering Science, 2010, 65(20): 5447-5454.
[30]	Wei X Y, Zhu J. Experimental investigation of the instantaneous flow structure in circulating fluidized bed: Phase characterization and validation[J]. Chemical Engineering Science, 2020, 228: 115946.
[31]	Schneiderbauer S, Pirker S. Filtered and heterogeneity-based subgrid modifications for gas–solid drag and solid stresses in bubbling fluidized beds[J]. AIChE Journal, 2014, 60(3): 839-854.
[32]	Harris A T, Davidson J F, Thorpe R B. The prediction of particle cluster properties in the near wall region of a vertical riser (200157)[J]. Powder Technology, 2002, 127(2): 128-143.
[33]	Gu W K, Chen, J C. A model for solid concentration in circulating fluidized beds[C] // Fluidization IX. New York, 1998: 501-508.
[34]	Subbarao D. A model for cluster size in risers[J]. Powder Technology, 2010, 199(1): 48-54.