Energy-saving exploration and optimization of methyl alcohol – Methyl ethyl ketone – Tertbutyl alcohol separation by extractive dividing-wall distillation with ionic liquid as extractant

Abstract

• Energy-saving separation of methyl alcohol - methyl ethyl ketone – tert -butanol azeotropic system is studied. • A few extractive distillation processes with ionic liquid are proposed and parametrically optimized. • The best one greatly reduces energy consumption, investment and CO 2 emission. • An efficient simulated annealing based optimization strategy is designed. Several new extractive distillation configurations using green and highly selective ionic liquid (IL) as extractant are proposed as an alternative to the conventional extractive distillation (CED) and conventional extractive dividing wall column (CEDWC) configuration to separate methyl alcohol (MeOH)-methyl ethyl ketone (MEK)-tert butyl alcohol (TBA) azeotropic mixture, including direct and indirect extractive distillation (direct-ED, indirect-ED), azeotropic extractive distillation (AED), and extractive dividing wall column (EDWC). These schemes are optimized with the objective of total annual costs (TAC) by simulated annealing based optimization method. Among these schemes, EDWC is undoubtedly the best due to the benefits of IL and dividing wall column. As compared with the CED process, it can reduce TAC by 22.19%, total capital cost by 31.47%, total operating cost by 8.35%, CO 2 emission by 7.7%. In addition, the computation shows that the used optimization method is very practical for the optimal design of complex distillation systems with the advantages of direct, efficient, robust and global optimal.