采用群体平衡模型模拟多段环流反应器内的气-液两相流动

摘要

The flow in a multi-stage air-lift loop reactor was studied by numerical simulation to optimize the effect of two-phase distribution.In addition,the comparative study was done about multi-stage air-lift loop reactors with different draft tube segmentation positions.The RNG k-εturbulence model and the population balance model (PBM)were employed in the simulation. Compared with the method of using uniform bubble diameter,the simulated values of gas holdup, liquid circulation velocity and the bubble size distribution by PBM were in good agreement with experimental values,meaning that the PBM simulation was of more accurate.The problem of uneven lateral mixing could be solved by adjustment of draft tube segmentation.Moving down the segmented location could effectively improve the down comer liquid circulation velocity and decrease average bubble diameter and thus improve the gas and liquid distribution effects.%采用 RNG k-ε湍流模型、欧拉-欧拉双流体模型和群体平衡模型(Population balance model,PBM),对一种中心气升式多段环流反应器的内部流场进行了数值模拟,并对反应器内导流筒分段位置进行了对比研究。结果表明,与均一粒径方法相比,采用 PBM 模型得到的气含率、循环液速和气泡粒径的分布规律与实验值吻合较好,可以更加准确地模拟环流反应器的流场及气泡运动规律；多段环流反应器分段位置的调整可以有效解决局部横向混合不均等问题,将分段位置下移可以提高下降区循环液速,减小气泡平均粒径,从而提高气-液分布及传质效果。