Design and Optimization of Pressure-Swing Distillation with Heat- Integration for Separating THF-Water Mixture

The most common separation technique used in chemical industries is distillation. The fundamental of distillation process is quite simple and could be applied widely for most mixtures with significant difference in boiling point. However, conventional distillation method cannot be used to separate azeotropic mixture effectively. In order to separate azeotropic mixture, pressure swing distillation can be utilized. Pressure swing distillation is commonly used for separation of azeotropic system, whose vapor-liquid equilibrium composition is strongly affected by pressure change. To improve the economy of distillation process, the energy consumption should be minimized. Heat integration is one of the methods to reduce energy consumption in distillation process. In pressure swing distillation, the energy recovered from the condenser of the high pressure column can be used to heat up the reboiler of the low pressure column. Heat integration could significantly improve the energy efficiency of the process. The aim of this research is to determine the optimal design of pressure swing distillation for separating azeotropic mixture of THF-water using total annual cost (TAC) as objective function with the help of Aspen Plus software. As distillation is an energy-intensive process, the use of heat integration is considered in order to assess its effect on the process economy. It is found that the optimal design of the pressure swing distillation with heat integration yields a significantly lower TAC of US$ 699,571.59 compared to the pressure swing distillation without heat integration, which has a TAC of US$ 832,396.95.