Design of Non-Linear, Time-Delay Control Systems: Application to Resilient Heat-Coupled Distillation Processes

This paper reports the first application of decoupling theory to design a multivariable (MV) controller for a 3-input 3-output heat-integrated double-effect distillation process having multiple state and control delays. An extended MV Smith´s compensator is theoretically established and subsequently employed to realize an effective feedback control system. This new MV time-delay compensator coupled with traditional proportional (P) controller is implemented on the non-linear distilling system possessing significant transportation lags in the recycle flows. A series of computer simulations reveal that the delay compensator dramatically improves the system responses and rejects feed disturbances. It is expected that even greater advantages over conventional P and PI controllers can be drawn in case of interconnected chemical process units where system delays, process disturbances and loop-interactions are considerably larger.