A GEOMETRIC DESIGN METHOD FOR SIDE-STREAM DISTILLATION-COLUMNS

A side-stream distillation column may replace two simple columns for s ome applications, sometimes at considerable savings in energy and inve stment. This paper describes a geometric method for the design of side -stream columns; the method provides rapid estimates of equipment size and utility requirements. Unlike previous approaches, the geometric m ethod is applicable to nonideal and azeotropic mixtures. Several examp le problems for both ideal and nonideal mixtures, including azeotropic mixtures containing distillation boundaries, are given. We make use o f the fact that azeotropes or pure components whose classification in the residue curve map is a saddle can be removed as side-stream produc ts. Significant process simplifications are found among some alternati ves in example problems, leading to flow sheets with fewer units and a substantial savings in vapor rate.