(48h) Multi-Pass Distillation Tray Optimization by Computational Fluid Dynamics Method

The flow pattern and mass transfer performance of a 12.6m in diameter 4-pass distillation tray column has been simulated by computational fluid dynamics (CFD) method. A two-dimensional pseudo single phase CFD model has been presented to describe the flow and mass transfer behavior. In the CFD model, both the resistance and bubbling effect of the uprising gas phase to the liquid phase are considered. In this paper traditional 4-pass tray design strategies including equal bubbling area method and equal flow-path length method were used to design the tray. Based on the proposed model, the liquid velocity profile and concentration distribution of both vapor and liquid phase on the tray were calculated. Simulated results show that there exists strong non-uniformity on one part of the tray while it is relatively uniform on the other part. To optimize the tray configuration and hence improve the tray separation efficiency, two modified tray structures were invented by adding several deflectors and changing weir shapes, respectively. Calculated results reveal that the Murphree efficiency of optimized tray is 1.94%~4.73% higher than that of traditionally designed tray.