Design and Control of Reactive Distillation Sequences with Heat-Integrated Stages To Produce Diphenyl Carbonate

Reactive distillation (RD) in quaternary systems has gained importance when one of the reagents is in excess. In this work, higher energy savings in a reactive distillation sequence is addressed to produce diphenyl carbonate, which is a crucial precursor of polycarbonate. Energy savings were attained through heat integration between the high-pressure RD column and the low-pressure separation column. The design of sequences with heat-integrated stages was done by combining simulation and optimization. The sequence with one heat-integrated stage realized the minimum energy consumption with energy savings around 22% and cost savings around 12% in comparison with the conventional reactive distillation sequence. Also, two control schemes for the best design configuration have also been studied in this work. The results showed-that the control scheme that manipulates the reboiler duty and reflux ratio to control two stage temperatures can provide excellent responses under throughput and feed composition disturbances. Furthermore, the feed ratio of the RD column is not the manipulating variable like in the conventional RD process. However, an internally stoichiometric balance result can be observed under composition disturbance.