Discrete and continuous approaches to the optimal synthesis of distillation sequences

Abstract

Recent developments in integer programming and in large-scale nonlinear programming allow the optimization of certain classes of chemical engineering plants. In this study two approaches for synthesizing distillation processes are presented and compared. In the discrete approach, an integer programming problem resulting from simplifying assumptions is solved with a branch-and-bound algorithm. In the continuous approach a large-scale nonlinear programming problem, whose formulation is rather difficult, is solved by means of a reduced-gradient algorithm. An example shows the complementary nature of the two approaches, the discrete approach providing a good initial feasible point for the continuous approach.