Optimal synthesis of multicomponent zeotropic distillation processes. 1. Preprocessing phase and rigorous optimization for a single unit

Separations performed by distillation involve large operation costs due to either large heat loads or large amounts of solvent used in azeotropic mixtures. Thermodynamic aspects helpfully lead the process synthesis to energetically efficient designs. The reversible distillation sequence model (RDSM) is employed in this work as a theoretical and ideal thermodynamic model. The aim of the paper is to present an automatic methodology for the synthesis of simple distillation columns that approximate reversible conditions. A preprocessing phase is considered where proper values to initialize and bound the variables involved in the rigorous model are calculated by successively solving auxiliary optimization models. In all cases studied, the solutions obtained are very similar to those in the so-called reversible separation. This fact is used as a test criterion for global optimality of the solutions.