Hybrid heat-integrated design and control for a diphenyl carbonate reactive distillation process

This study proposed the design and control system of a hybrid heat-integrated configuration for the diphenyl carbonate (DPC) indirect reactive distillation (RD) process. First, an existing DPC production process with an RD column and a distillation column (C1) as the base case was modified and optimized for further evaluation. Both thermally coupled distillation (TCD) and double-effect (DE) configurations were examined to simultaneously improve the energy efficiency. A hybrid heat-integrated configuration for the DPC indirect RD process was finally proposed. The remixing effect at the top part of the RD column could be removed, and the energy wastage in the condenser of the C1 was lower than that in the TCD configuration. The heat exchanger (HE) area was smaller than that in the DE configuration. Among all configurations, the hybrid configuration was superior; around 34.0 % of energy could be saved for producing 99.5 mol% of DPC. Then, three control structures (CS1, CS2, and CS3) and two inventory control loops (inventories A and B) were proposed in the hybrid heat-integrated configuration. Pressure-compensated temperature (PCT) control was also applied to eliminate the effect of pressure floating. The dynamic simulation results revealed that the CS3 PCT could maintain specifications during throughput and composition disturbances.