Comparison of different extractive distillation processes for 2-methoxyethanol/toluene separation: Design and control

•The azeotropic mixture of 2-methoxyethanol and toluene is separated using extractive distillation process.•Three different extractive distillation configurations are investigated and optimized.•Extractive distillation under reduced pressure operating at a relatively low pressure is more economic than that operating at the lowest pressure.•The extractive dividing-wall column process shows greater economic benefits over the other two processes.•The improved control structure of the extractive dividing-wall column process is effective to overcome the feed disturbances.

In this work, the extractive distillation process is proposed for the first time to separate the 2-methoxyethanol/toluene mixture. Three configurations, including the conventional extractive distillation (CED), extractive distillation under reduced pressure (EDRP) and extractive dividing-wall column (EDWC) processes are investigated in order to obtain the optimal separation configurations. Their economic feasibilities are estimated by calculating the total annual cost (TAC). The results show that the EDRP process operating at a relatively low pressure is more economic than that operating at the lowest pressure. The TAC of the EDRP and EDWC processes can be saved by 4.88% and 11.04% respectively compared to the CED process, thus the EDWC sequence is superior to the other two processes in economic benefits. Three control strategies are proposed to investigate the controllability of the EDWC process. The results show that the improved dynamic structure can overcome large feed disturbances in flowrate and composition effectively.