Control of side-stream pressure-swing distillation and extractive distillation for separating azeotropic mixture of cyclohexane and acetone

Dynamic controls of a side-stream pressure swing distillation (PSD) and extractive distillation (ED) process for cyclohexane and acetone separation are investigated. The processes operating parameters are optimized with a sequential iterative procedure based on the total annual cost (TAC). The dynamic result shows that for the side-stream PSD process, a modified control structure 2 (CS2) with the composition controller (CC) cascaded with the temperature controller 2 (TC2) can efficiently handle the feed disturbances, with the output signal being the ratio of reboiler duty to feed flow rate (QR/F). For the ED process, a modified control structure 4 (CS4) with the acetone product composition controller as the characteristic control loop can efficiently handle the disturbances which is controlled by the ratio of solvent flow to feed flow rate (S/F). A comparison of the side-stream PSD process and the ED process shows the former has decent dynamic performance.