Selecting the Best Entrainer for Separation of Ethanol and Water Azeotropic Mixture to Reduce Energy Consumption

Azeotropic and extractive distillation processes are two common methods for separation of azeotropic mixtures. Both methods utilize a third substance, referred to as entrainer, that alters the vapor–liquid equilibrium, facilitating separation of an azeotropic mixture. However, as in any other distillation tower (column), azeotropic and extractive distillation processes consume a large amount of energy, and given the significant effect of entrainer on energy consumption, selecting a suitable entrainer is considered a key parameter in the design these processes. Three different entrainers were used in this study for separation of an azeotropic ethanol–water mixture. In azeotropic distillation, benzene and cyclohexane were used as entrainers, whereas for extractive distillation, ethylene glycol was used. The results indicated that the latter achieved a higher performance both in terms of separation and energy consumption compared to the former. Extractive distillation with ethylene glycol as entrainer reduced the hot and cold utility by ۹۲ and ۴۳ percent, respectively, compared to azeotropic distillation.

Keywords:

azeotrope , extractive distillation , azeotropic distillation , entrainer , energy consumption