Analysis of Entropy Production Rates for Design of Distillation Columns

The entropy production rate for a distillation column is at a minimum when the driving forces for separation are uniformly distributed along the column. This theoretical result was derived for separation of binary mixtures having linear flux-force relations with coefficients which vary with temperature and composition. The entropy production rate was first calculated numerically for separation of an ideal and a nonideal mixture. The application of the principle, called the principle of equipartition of forces, was then demonstrated by analyzing the effect of distributed heating in a column with an ideal mixture. A reduction in the entropy production rate per m{sup 3} of product formed of up to 7% was found for the system plus surroundings, after seeking equipartition of forces with minimum changes in the apparatus.