Modeling and Optimization Study of Pressure-Swing Distillation for the Separation Process of Acetone–Methanol Mixture with Vapor–Liquid Equilibrium Analysis

Abstract

The azeotropic point of the binary system of acetone–methanol varies sensitively depending on the pressure change. This principle can be applied in order to obtain substantially pure acetone and methanol by using two distillation columns operated in sequence at two different pressures. The process of separation through this mechanism is known as pressure-swing distillation (PSD). This study mainly focused on the modeling and optimization of the PSD process as an effective method of separating an azeotropic mixture of acetone–methanol. The proper thermodynamic model to be used in the simulation was selected based on the prediction of the liquid activity model which gives the best fit for the experimental vapor–liquid equilibrium data of the involved binary system. For the simulation works, PRO/II with PROVISION v9.2 was utilized to create a model of PSD using two column configurations, a low–high pressure (LP+HP) column configuration and a high–low pressure (HP+LP) column configuration. The optimum theoretical number of stages, reflux ratios and feed stage locations were determined for the low-pressure (LP) column and high-pressure (HP) column to minimize the heat duty. Since PSD operates at different pressures, the hot and cold utility consumption is quite large. Therefore, heat integration was applied to the system to eliminate the high– and low– temperature utility consumption of the reboiler and condenser.