Simulation and Optimization of Pressure-swing Distillation for Separating an Acetonitrile-ethanol Azeotrope
The Aspen Plus software was utilized to simulate and optimize a pressure-swing distillation process for the separation of the atmospheric azeotrope in the acetonitrile-ethanol system,using the Wilson activity coefficient model for physical property calculations.The operating pressures for the pressurized and atmospheric columns were respectively chosen as 250 and 101.325 kPa.The temperature profiles of the trays in both columns were examined for different numbers of theoretical trays,with a focus on evaluating the impact of feed tray locations and reflux ratios on the total heat duty of the two reboilers while ensuring a purity level of 99.9％ for both acetonitrile and ethanol products.Subsequently,the optimum process parameters were determined as follows:for the pressurized column,there are 15 theoretical trays,with the feed tray located at the 5th tray,and a reflux ratio of 1.4;for the atmospheric column,there are 14 theoretical trays,with the feed tray located at the 5th tray,and a reflux ratio of 1.2.Based on these optimization results,the energy consumption of both the conventional and heat-integrated pressure-swing distillation processes was analyzed.The results indicate that the heat-integrated pressure-swing distillation process saves 41.69％ of energy compared with the conventional process.
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