Novel dynamic control structure of reactive distillation process for isopropanol production via transesterification

Due to the complicated interaction between reaction and separation in a column, it was inherently challenging to design a control structure for the reaction distillation process. In this research, the control structures of the hybrid reactive distillation process combining pressure-swing distillation (RDC-HDC) and its thermal coupling (RDWC-HDC) processes, were explored for producing isopropanol (IPA) by isopropyl acetate (IPAC) with methanol (MeOH) transesterification. The control performances of only temperature control and temperature difference control schemes for RDC-HDC process were first investigated. The research results displayed that double temperature control (CS3) and temperature difference control schemes (CS4-1, CS4-2 and CS5) for the RDC-HDC process could shorten the maximum transient deviation, amplitude of oscillations and setting time in face with +/- 20% throughout and +/- 5% feed composition disturbances. To further improve control characteristics and make control structures concise, a novel control strategy (CS6) by a proportional controller adjusted by reverse action of an IPAC component controller in 34 trays for keeping IPAC composition at a certain range in the RDC-HDC process was developed based on the closed loop analysis before and after disturbance. The application of the innovative control structures (CST4) to the RDWC-HDC process was equally feasible in face of +/- 10% throughout and +/- 5% feed composition disturbances. The analysis of integral of squared error (ISE) indicated that a novel control strategy (CS6 and CST4) had better robustness and dynamic performance. These studies contributed to the development of controllability for hybrid reactive distillation processes to produce chemicals for reaction and separation.