塔板上流型变化对板效率影响的计算传质学

NUMERICAL STUDY OF MASS TRANSFER PROCESS ON DISTILLATION TRAY USING COMPUTATIONAL FLUID DYNAMIC METHOD

利用能够描述塔板上气液两相错流过程的流体力学模型 ,建立了同时模拟气液两相流动与传质过程的数学模型 ;通过对气液两相传质方程和流体力学模型方程的联立求解 ,计算得到了塔板上液相速度分布和气液两相浓度分布的数值解 ,考察了气相完全混合和气相部分混合两种条件下塔板上的气液两相浓度分布 。

It has long been recognized that liquid flow pattern especially liquid circulation, or reverse flow, is of great importance in determining tray efficiency. Research work concerning tray efficiency calculation is reviewed and a mathematical model which combines computational fluid dynamic model with mass transfer equation to predict the details of the mass transfer process on a distillation tray is proposed. By solving the proposed model, the velocity distribution of liquid phase and concentration profiles of vapor and liquid phases can be calculated simultaneously. Complete mixing and partial mixing of vapor phase is investigated in simulating the details of mass transfer process. The result reveals that the tray efficiency calculated in the assumption of complete mixing of vapor phase is greater than the real value. The computed results verify the qualitative assumption that the vapor leaving the liquid circulation region has very little change in concentration. The quantitative results of tray efficiency vs. the size of circulation region is given.