Control of a pressure-swing distillation process for benzene/isopropanol/water separation with and without heat integration

Abstract

Controlling the behavior of processes for the recovery of benzene and isopropanol from industrial wastewater is an important topic. In this work, dynamic control structures are investigated for the separation of azeotropic water, benzene, and isopropanol mixtures using triple column pressure-swing distillation (without heat integration, with partial heat integration, and with full heat integration). Composition and flow disturbances are utilized to examine the performance of the control structure, and four improved control structures are developed and show good control effects. The ratio of reboiler duty to mole feed flow rate control structure showed good control behavior in face of the disturbances for the ternary pressure swing distillation processes. The integral of squared error (ISE) values of the control structure was combined with the dynamic response curves to compare the performance of the control structures. The ISE value of the improved control structure with full heat integration was smaller than that of the improved control structure without heat integration and the improved control structure with partial heat integration. The total annual cost (TAC) of the full heat integration process was also lower than the values for the other three processes. Based on its control performance and TAC, the improved control structure with full heat integration was concluded to be the best of the control structures. This work can serve as a reference for industrial development.