A new clean and energy-saving process design of extractive distillation for ethyl propionate/n-propanol/H2O heterogeneous azeotrope system

Abstract

The development of efficient wastewater treatment technologies is crucial for the sustainable advancement of the chemical, pharmaceutical, and food industries. In this study, the azeotrope of ethyl propionate/n-propanol/water in liquor wastewater was successfully separated via extractive distillation and extractive pressure swing distillation technologies. Ethylene glycol was determined as the optimal entrainer based on relative volatility, and the interaction between azeotrope and entrainer was further explored through electrostatic potential and σ-profile analysis. We employed the multi-objective optimization method to optimize different process flows, focusing on total annual cost and gas emissions as objective functions. The optimal solutions weighing economic and environmental factors were obtained. Additionally, heat-integrated technology was used to explore energy-saving distillation processes to tackle the issue of excessive energy consumption. Finally, eight separation processes were discussed and analyzed from the perspective of economic, environmental, energy, and exergy. The findings indicated that the heat-integrated new four-column pressure swing-assisted extractive distillation process exhibited the most favorable environmental and economic performance. Compared with the extractive distillation process, the heat-integrated new four-column pressure swing-assisted extractive distillation scheme achieved a reduction of 28.14% in total annual cost and 47.47% in gas emissions. This study provides valuable insights for recycling ethyl propionate and n-propanol from industrial wastewater and has certain reference significance for future research.