Economic, Environmental, and Safety Multi-Objective Optimization Design for Separation of Tetrahydrofuran/Methanol/Water Mixture

Tetrahydrofuran (THF) and methanol (MeOH) are widely used as organic solvents in chemical, pharmaceutical, and other industrial fields. The wastewater from producing 1,4-butanediol contains THF, MeOH, and water ternary azeotropic mixture. In this study, to protect the environment and improve economic feasibility, THF and MeOH from the wastewater must be recovered. Triple-column extractive distillation (TED), pressure-swing azeotropic distillation (PSAD) and reactive extractive dividing-wall column (REDWC) are introduced to separate this ternary system, and the NSGA-III algorithm is introduced to optimize the processes, taking the total annual cost (TAC), CO2 emissions, and process route index (PRI) as objective functions. The results indicate that in comparison with TED process, TAC of PSAD and REDWC is reduced by 29.92% and 24.25%, respectively, and CO2 emissions decreased by 18.01% and 25.13%, while PRI increased by 150.25% and 100.50%. This study can provide an insight for the design of ternary azeotropic system separation.