Multipass flow distribution and mass transfer efficiency for distillation plates



A new model for predicting the hydrodynamics, flow distribution, and mass transfer efficiency of multipass distillation trays is presented. Separate submodels apply to two-, three-, and four-pass trays, which may be any type of cross flow tray with downcomers: sieve, valve, or bubble cap.

It was found that the liquid/vapor flow ratio in one pass of a poorly designed multipass tray can be several times that in adjacent passes, and that the mean tray efficiency of such a tray is substantially less than the optimum possible. It is shown that multipass trays can be designed with essentially perfect flow distribution and optimum (maximum) overall tray efficiency.