Pressure swing distillation of azeotropic mixture – A simulation study

SummaryThe aim of this work is to simulate a pressure-swing distillation column for the separation and purification of ethanol from the ethanol–water binary system. The choice for this system is due to the importance of the ethanol–water separation. A steady-state equilibrium-stage model based on normalised MESH equations is used to simulate pressure-swing distillation column applied for the production of ethanol. All the work has been carried out using Aspen Plus simulator, version 13.2. Among the activity coefficient models available, the WILSON-RK model with binary parameters predicted by the Aspen Plus simulator is shown to be the most accurate to correlate the experimental vapor-/liquid equilibrium (VLE) data available for the ethanol–water system. The simulation has been satisfactorily carried out for a mixture of 20mol% ethanol in water at 1atm pressure and 90°C with a molar flow rate of 100kmol/h. The adjusting parameters include D/F ratio and reflux ratio of the two columns to get water purity of 99.5mol% from the bottom of the Low Pressure Column (LPC) and the ethanol purity of 99.7mol% from the bottom of High Pressure Column (HPC)