Abstract:
A double-layered model predictive control strategy is designed for the process of vinyl chloride distillation in order to address problems associated with high energy consumption, multivariable coupling, large time delays, high-boiling compounds that cannot be automatically discharged, and reflux optimization control of a high-boiling column. The strategy considers the temperature difference of the rectification section; thus, with the aim of achieving process control in high-boiling column distillation, the developed strategy optimizes reflux energy savings. In addition, the logic associated with the auto discharge of high-boiling compounds is designed by considering the rectifier-bottom temperature and level, and it is shown that this logic is effective for its purpose. Simulation results show that the proposed strategy can indeed reduce the process fluctuation of high-boiling columns caused by feed disturbance and achieve auto discharge of high-boiling compounds and optimization of the reflux.