New Pressure-Swing Distillation for Separating Pressure-Insensitive Maximum Boiling Azeotrope via Introducing a Heavy Entrainer: Design and Control

Abstract

In this work, the pressure-swing distillation process is extended to separate the pressure-insensitive binary azeotropes by using suitable entrainers. Design and control of new pressure-swing distillation for separating pressure-insensitive maximum boiling phenol/cyclohexanone azeotrope using acetophenone as a heavy entrainer are investigated using Aspen Plus and Aspen Dynamics. Rigorous steady-state simulations are run for both fully and partially heat-integrated processes and a comparison of these two configurations is made. It is revealed that the partially heat-integrated process is more competitive than the fully heat-integrated one from the economical viewpoint. Two temperature control structures and one composition/temperature cascade control scheme are proposed to handle the feed flow rate and feed composition disturbances. It is indicated that the column operating at higher pressure cannot be perfectly controlled by the two temperature control schemes because of the existence of an intermediate nonkey component. A composition/temperature cascade control structure is proposed to cope with this control problem and a robust control is achieved.