Distillation of multicomponent mixtures

Abstract

A synopsis is given of a recent theory of distillation of multicomponent mixtures in which the product of absorption factors is calculated from a summation equation. A constant ratio of volatilities is assumed. The calculation of a distillation at variable reflux can be reduced to one at constant molar reflux. The theory is applied to a distillation at constant reflux. The summation equation is solved either by successive calculation of the absorption factor product or algebraically or by graphical methods. The successive calculation is by far the quickest if only one reflux ratio is considered. The algebraic method involves the solution of two algebraic equations of higher order than two. It is shown that the multicomponent mixture may be approximated by two binary mixtures and if this is done quadratic or even linear equations have to be solved only. Even so, however, the algebraic solution takes up much time. The graphical method is also based upon the approximation by binary mixtures. It is preferred to the algebraic method on account of its quickness and it is easily surveyable. Graphs are given from which all possible columns and reflux ratio's which lead to the desired distillate and residue, can be found.