Heuristic synthesis for multicomponent products with simple and sharp separators

Abstract

A heuristic method for the synthesis of flowsheets with simple, sharp separators for multicomponent products is proposed. When a separation system is to produce multicomponent products, it is frequently not necessary to separate a feed mixture completely into pure components. In this paper, therefore, stream bypassing around separators and limited stream splitting are permitted to reduce both capital and operating costs by reducing mass load on the separators. Heuristic rules with priority are proposed to identify the maximum bypassing, parallel processing, separation sequencing and minimum blending, which embody knowledge of the general behavior of flow patterns, separation units and separation sequences. The proposed method has been applied to a number of synthesis problems which have been solved previously using other methods. The results show that the flowsheets synthesized by the heuristic method are either better than or at least identical to those optimum flowsheets obtained by other mathematical programming and evolutionary methods. The proposed heuristic method offers a simple and effective means for design engineers to generate several good initial flowsheets for multicomponent multiproduct separations prior to the final heat integration and multiobjective design optimization.