Optimum Control of a Divided Wall Distillation Column

Dynamic responses were obtained from a pilot scale divided wall distillation column. The results were compared to predictions obtained from a non-steady state gPROMS model. Various control strategies were implemented on the experimental column and incorporated into the dynamic model to determine the optimal control methodology. As part of this effort, temperature pairings for the reflux, liquid split, side stream, and reboiler steam were evaluated to determine the optimal temperature measurement locations for composition control. Model predictive control was evaluated as a control strategy. The manipulated variables for the MPC were the reflux flow, side stream, reboiler steam flow, and the cross-wall liquid split, with the steam flow and liquid split being controlled using state-of-the-art wireless control.