Thermodynamic optimization and industrial feasibility of heat pump distillation–membrane coupling for bioethanol purification

Abstract To address the high energy consumption of conventional three‐column distillation for fuel ethanol purification, this study proposes an energy‐saving heat pump distillation–membrane coupling process with three core innovations: integrating pressure‐swing column thermal coupling, heat pump‐driven steam grade enhancement, and ZIF‐8‐PDMS/PVDF mixed matrix membranes (MMMs) for deep dehydration; developing a membrane micro‐element model to make up for the lack of dedicated mass‐energy coupling membrane modules in commercial simulators; optimizing key parameters via Aspen Plus. Under the optimal conditions (crude/first/seconds columns with 11/8/24 theoretical plates, reflux ratios of 1.63/0.61/0.80, MMM area of 1336.67 m 2 ), the fuel ethanol purity reaches 99.46%. Compared with the conventional three‐column distillation process, the total annual cost (TAC) decreases by 9.78% to 5.475 × 10 6 USD · a −1 , CO 2 cost reduces by 20.92%, and the column top‐bottom temperature difference is 27.7°C (close to the 35°C economic threshold). This work promotes the application of ZIF‐8‐PDMS/PVDF MMMs in bioethanol dehydration and provides an industrial low‐energy green solution.