Design and Optimization of Sustainable Pressure Swing Distillation for Minimum-Boiling Azeotrope Separation

A systematic approach for designing an energy-saving and environmentally friendly pressure swing distillation (PSD) process for separating binary azeotropes is proposed and involves the initial determination of the operating pressure and separating sequence based on the temperature-composition (T-xy) diagram, optimization by the two-step optimization procedure via minimizing the lifetime total cost (LTC), heat integration (HI), and a heat pump to achieve further energy savings and increase the process sustainability. The Eco-indicator 99 (EI99) is first introduced as an assessment criterion to evaluate the damage to the environment and sustainability of the PSD process. The partial and full HI-PSD processes are studied, and their corresponding T-H diagrams are provided to evaluate the feasibility and degree of heat integration. Three HP-PSD processes are investigated and optimized by minimizing the LTC. The results show that compared with the literature design, our conventional PSD process reduces the LTC and EI99 by 43.42% and 47.86%. The partial HI-PSD processes could further decrease the LTC and EI99 by 20.71% and 27.19% compared with the conventional PSD process. Meanwhile, the full HP-PSD process could reduce the LTC and EI99 by 14.12% and 68.77% compared to the partial HI-PSD process. Hence, the full HP-PSD process is the most favorable from both economic and sustainability perspectives.