CFD based investigations on hydrodynamics and energy dissipation due to solid motion in liquid fluidised bed
CFD based investigations on hydrodynamics and energy dissipation due to solid motion in liquid fluidised bed
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DOI：
10.1016/j.cej.2007.01.042
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发表时间：
2007-08
影响因子：
15.1
通讯作者：
R. Panneerselvam;S. Savithri;G. D. Surender
中科院分区：
文献类型：
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作者：
R. Panneerselvam;S. Savithri;G. D. Surender
采用欧拉-欧拉框架对液固流化床内的流型进行了CFD模拟。计算流体动力学模型的预测结果与Limtrakul等人报道的实验结果进行了比较[S. Limtrakul，J. Chen，P.A.李文，液体流化床中固体颗粒的运动与持液率分布，北京：科学出版社，2000。60（2005）1909-1920]并且比较显示出良好的一致性。计算流体力学模型已被进一步扩展，以计算固体质量平衡的核心和环形区域验证守恒的质量和能量流，由于各种耗散机制。在液体流化床中固体膨胀所需的能量也与在类似操作条件下在等效搅拌釜接触器中固体悬浮所需的能量进行了比较。Gidaspow提出的各种相间阻力模型的影响[D. Gidaspow，多相流和流化，第1版，Academic Press，San Diego，1994]，Di Felice et al. [R. Di Felice，流体-颗粒相互作用系统的空隙率函数，Int. J. Multiphase Flow 20（1994）153-159]和Syamlal和奥布莱恩[M. Syamlal，T. J.奥布莱恩，液体流化床中颗粒层反转的模拟，国际多相流杂志14（1988）473-481]研究了液体流化床中固体运动。尽管这些模型预测流化床内固体运动的流型具有合理的精度，Gidaspow提出的模型与实验数据表现出更好的定量一致性。为了保证数值模拟预测的准确性，对二维和三维模拟、网格敏感性、时间步长敏感性和进料条件的影响进行了对比，提出了一种综合的CFD方法来模拟液固流化床的流体力学。
CFD simulations are carried out for the prediction of flow patterns in a liquid–solid fluidised bed using Eulerian–Eulerian framework. The CFD model predictions are compared with the experimental findings reported by Limtrakul et al. [S. Limtrakul, J. Chen, P.A. Ramachandran, M.P. Dudukovic, Solids motion and holdup profiles in liquid fluidised beds, Chem. Eng. Sci. 60 (2005) 1909–1920] and the comparison shows good agreement. The CFD model has been further extended to compute solid mass balance in the core and annular regions for verifying conservation of mass and energy flows due to various dissipation mechanisms. Energy required for solid expansion in liquid fluidised bed is also compared with energy required for solid suspension in an equivalent stirred tank contactor at similar operating conditions. The influence of various interphase drag models proposed by Gidaspow [D. Gidaspow, Multiphase Flow and Fluidisation, 1st ed., Academic Press, San Diego, 1994], Di Felice et al. [R. Di Felice, The voidage functions for fluid–particle interaction system, Int. J. Multiphase Flow 20 (1994) 153–159] and Syamlal and O’Brien [M. Syamlal, T.J. O’Brien, Simulation of granular layer inversion in liquid fluidised beds, Int. J. Multiphase Flow 14 (1988) 473–481] on solid motion in liquid fluidised bed have been investigated. Even though these models predict the flow pattern of solid motion inside the fluidised bed with reasonable accuracy, the model proposed by Gidaspow showed the better quantitative agreement with experimental data. For ensuring accuracy of numerical simulation prediction, comparisons between 2D and 3D simulation, the effect of grid sensitivity, time step sensitivity and effect of inlet feed conditions have been carried out and a comprehensive CFD methodology is proposed to model the hydrodynamics of liquid–solid fluidised bed.