Dynamic control of an energy-saving process with two extractive dividing-wall columns for separation of acetone/methanol/butanone/ tert-butyl alcohol mixtures

In the chemical and petrochemical industries, an azeotropic mixture of acetone/methanol/butanone/tert-butanol needs to be separated for high-purity products. Following a previous work in which an energy-saving process composed of two extractive dividing-wall columns (EDWCs) was developed for the quaternary system, this paper focuses on the issue of dynamic control for this process. Several control strategies in combined with temperature control, temperature-difference control and composition control are established to maintain the purity of all products in the face of disturbances in feed flow and feed composition. Dynamic simulations demonstrate that a conventional temperature control structure provides very poor control while a control strategy that used threetemperature-difference control for both EDWCs is the most effective.