Distillation Calculation by Multistage Relaxation Methods

Abstract

Multistage relaxation methods are proposed for solving nonideal multicomponent distillation problems involving multiple feeds and side-cut streams. In the present work, two-stage and three-stage relaxation algorithms are developed from a single-stage relaxation algorithm with simultaneous correction of liquid composition and temperature.
From a feasibility study using numerical examples, the two-stage relaxation method is recommended since the effect of the formulation complexity on the improvement of convergence is higher than that of the three-stage method.