Environmental and economic optimization of the pressure-swing distillation process for separation of azeotropic mixture of Acetonitrile-Water

Abstract

The separation of azeotropic mixtures is a significant challenge in chemical engineering, particularly when using pressure-swing distillation. This study focuses on the Pressure-Swing Distillation process for the separation of the azeotropic mixture Acetonitrile-Water, using global optimization via simulated annealing, assessing both economic (Total Annual Cost) and environmental impacts (carbon dioxide emission and Eco-indicator 99). The results aim to guide decision-making by highlighting the trade-offs in electrifying the Pressure-Swing Distillation process for Acetonitrile-Water. Heat integration between the low-pressure column reboiler and high-pressure column condenser results in substantial cost and environmental improvements, reducing Total Annual Cost by 23.53 %, Total Operating Cost by 42.2 %, and carbon dioxide emissions by 42.2 %. Additionally, the Eco-indicator 99 drops from 171,977 to 99,343 points/year. Electrifying steam generation further reduces carbon dioxide emissions from 91.97 to 72.29 kg/h but increases Total Operating Cost by 39.72 k$/year, making it economically unfeasible under the present conditions. Vapor recompression reduces Eco-indicator 99 by 72.39 % and carbon dioxide emissions by 75.18 % compared to heat integration, but its higher costs make it viable only with a payback period of over 5 years. The shift from fossil fuels to electricity also alters the primary environmental impact, highlighting the need for renewable energy sources to fully optimize the process environmentally.