Fine grid DEM simulation of bed layer height in bubbling fluidized-bed

doi:10.3969/j.issn.0438-1157.2014.06.020

Abstract

Abstract: For fine-grid DEM simulation of gas-solids fluidized-bed, the traditional methods of calculating grid porosity and local porosity lead to large deviations in simulation results. This paper gives a precise area fraction model and a completely circumstance-dependent local porosity model to more properly calculate grid porosity and local porosity, respectively. These models were validated by the DEM simulation test on a small-scale bubbling fluidized system, using fine-grid size of two particle diameters. The simulated bubble shape and size were close to the measurement. Simulations showed that DEM could perform well in modeling time-varying waveforms for the bed layer height, when using the precise area fraction model and the local porosity model.

Key words: fluidized-bed, multiphase flow, simulation, DEM, drag force, fine grid

摘要： 气固流化床DEM的细网格模拟中，采用传统方法计算网格空隙率和局部空隙率会对模拟结果造成较大偏差，给出一个精确面积分数模型和一个完全依赖颗粒环境的局部空隙率模型，从而更加合理地计算网格空隙率和局部空隙率。采用二倍颗粒直径的细网格模拟了小规模鼓泡流化床，模拟的气泡形状和尺寸与实验结果接近。模拟结果表明：采用给出的面积分数模型和局部空隙率模型能较好地模拟鼓泡流化床床层高度随时间变化的波形。

关键词: 流化床, 多相流, 模拟, DEM, 曳力, 细网格

CLC Number:

TQ051.1

WU Guorong, OUYANG Jie. Fine grid DEM simulation of bed layer height in bubbling fluidized-bed[J]. CIESC Journal, 2014, 65(6): 2092-2097.

吴国荣, 欧阳洁. 鼓泡床床层高度的细网格DEM模拟[J]. 化工学报, 2014, 65(6): 2092-2097.

References 15

[1]	Jin Yong (金涌), Zhu Jingxu (祝京旭), Wang Zhanwen (汪展文), Yu Zhiqing (俞芷青). Fluidization Engineering Principles (流态化工程原理) [M]. Beijing: Tsinghua University Press, 2001
[2]	Tsuji Y, Kawaguchi T, Tanake T. Discrete particle simulation of two-dimensional fluidized bed [J]. Powder Technol., 1993, 77 (1): 79-87
[3]	Hoomans B P B, Kuipers J A M, Briels W J, van Swaaij W P M. Discrete particle simulation of bubble and slug formation in a two-dimensional gas-fluidized bed: a hard-sphere approach [J]. Chem. Eng. Sci., 1996, 51 (1): 99-108
[4]	Xu B H, Yu A B. Numerical simulation of the gas-solid flow in a fluidized bed by combing discrete particle method with computational fluid dynamics [J]. Chem. Eng. Sci., 1997, 52 (16): 2785-2809
[5]	Ouyang J, Li J H. Particle-motion-resolved discrete model for simulating gas-solid fluidization [J]. Chem. Eng. Sci.,1999, 54 (13): 2077-2083
[6]	Zhu H P, Zhou Z Y, Yang R Y, Yu A B. Discrete particle simulation of particulate systems: theoretical developments [J]. Chem. Eng. Sci., 2007, 62 (13): 3378-3396
[7]	Zhu H P, Zhou Z Y, Yang R Y, Yu A B. Discrete particle simulation of particulate systems: a review of major applications and findings [J]. Chem. Eng. Sci., 2008, 63 (23): 5728-5770
[8]	Ouyang Jie (欧阳洁), Li Jinghai (李静海). Advances of determinate particle-trajectory model in simulation of fluidized beds[J]. Journal of Chemical Industry and Engineering (China) (化工学报), 2004, 55 (10): 1581-1592
[9]	Link J M, Cuypers L A, Deen N G, Kuipers J A M. Flow regimes in a spout-fluidized bed: a combined experiment and simulation study [J]. Eng. Sci., 2005, 60 (13): 3425-3442
[10]	Wu Guorong (吴国荣). Coarse grid DEM simulation and drag modelling of gas-solid fluidized bed [D]. Xi'an: Northwestern Polytechnical University, 2012
[11]	Wu G R, Ouyang J, Li Q. Revised drag calculation method for coarse grid Lagrangian-Eulerian simulation of gas-solid bubbling fluidized bed [J]. Powder Technol., 2013, 24: 68-78
[12]	Wen C Y, Yu Y H. Mechanics of fluidization [J]. Chem. Eng. Prog. Symp. Ser., 1966, 62: 100-111
[13]	Patankar T V. Numerical Heat Transfer and Fluid Flow [M]. New York: McGraw-Hill, 1980
[14]	van Wachem B G M, van der Schaaf J, Schouten J C, Krishna R, van den Bleek C M. Experiment validation of Lagraingian-Eulerian simulation of fluidized beds [J]. Powder Technol., 2001, 116: 155-165
[15]	Wu G R, Ouyang J, Yang B X, Li Q. Use of compromise-based local porosity for coarse grid DEM simulation of bubbling fluidized bed with large particles [J]. Adv. Powder Technol., 2013, 24 (1): 68-78