液固流态化动态过程中相间作用力的数值模拟及实验验证  

Numerical simulation and experimental validation of inter-phase forces in dynamic process of liquid-solid fluidization

作　　者：张仪[1] 李兵[1] 白玉龙 张锴[1] ZHANG Yi;LI Bing;BAI Yulong;ZHANG Kai(Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学热电生产过程污染物监测与控制北京市重点实验室,北京102206

出　　处：《化工学报》2020年第11期5129-5139,共11页CIESC Journal

基　　金：国家自然科学基金与山西煤基低碳联合基金重点项目(U1910215);中央高校基本科研业务费专项资金(2018ZD03,2020MS064)。

摘　　要：选择恰当的相间作用力模型是液固流态化动态特性CFD建模的关键。首先采用Richardson-Zaki关联式验证了稳态操作条件下整体固含率的实验结果,然后在基于颗粒动理学理论的欧拉-欧拉双流体模型中比较了Wen-Yu、Gidaspow、Syamlal-O’Brien、Dallavalle和TGS5个曳力计算公式对液固流化床收缩和膨胀特性的数值模拟结果,进而探讨了Moraga等提出的升力模型影响行为及主要相间作用力影响机制。与实验测量数据比较结果表明:收缩过程中Syamlal-O’Brien和TGS曳力模型对响应时间预测较为准确,TGS曳力模型对整体固含率的预测精度较高;膨胀过程中TGS曳力模型对响应时间和整体固含率的预测优于其他模型。整体而言,基于静止颗粒群绕流直接模拟得到的TGS曳力模型忽略了颗粒-颗粒相互作用,与液固散式体系中颗粒动力学特性相符合。升力模型对动态特性模拟结果影响较小,CFD模拟时根据选择体系可予以适当忽略。Choosing the appropriate interphase force model is the key to CFD modeling of liquid-solid fluidization dynamic characteristics. Measured overall solids holdups are validated by Richardson-Zaki correlation under steady-state operating conditions. Then five drag formulas including Wen-Yu, Gidaspow, Syamlal-O’ Brien,Dallavalle and TGS are assessed in the contraction and expansion processes by using Euler-Euler two-fluid model with the kinetic theory of granular flow. Furthermore, the influence of the classical lift model suggested by Moraga et al. on CFD predictions and the influence mechanism of main inter-phase forces are discussed. The results compared with the experimental data show that the response time of bed contraction process predicted by Syamlal-O’Brien or TGS drag model is more accurate than those by the others. Moreover, TGS drag model shows the most reasonable prediction in overall solids holdup. For the bed expansion process, TGS drag model gives more reliable prediction in the response time and overall solids holdup than the other models. The main reason behind the best hydrodynamic performance with TGS drag model in this study is that the modeling basis of TGS drag model is consistent with the dynamic behaviors of particles in liquid-solid system. The lift model has little influence on the CFD results, and thus it can be ignored in the modelling of inter-phase force for the dynamic characteristics according to the homogeneous liquid-solid fluidized system investigated in this study.

关 键 词：计算流体力学 实验验证 流化床 液固两相流 动态特性 相间作用力 

分 类 号：TQ021.1[化学工程] O359[理学—流体力学]