Multicomponent tray efficiencies accounting for entrainment

Abstract

In multicomponent distillation, the component point efficiencies are highly sensitive to the composition profiles and are known to exhibit bizarre behavior. A major limitation of these efficiencies is the fact that they cannot be related to tray efficiencies for dispersed and plug flow of liquid, unless multicomponent effects are ignored — these would still pose a problem if the component point efficiencies assume large negative values. The Maxwell—Stefan approach to diffusion in multicomponent mixtures leads to a component point efficiency matrix which does not suffer from these drawbacks. In this work, rigorous methods are pesented for obtaining a tray efficiency matrix from a point efficiency matrix for dispersed flow and plug flow of a liquid phase, and accounting for the entrainment. The results of the simulation of the fractionation of two ideal and two non-ideal mixtures indicated the superiority of the matrix approach over the use of component efficiencies.