Separation And Simulation For Ethanol-Acetonitrile Mixture

Ethanol and acetonitrile are very important organic solvents and synthesis additives, which are widely used in chemical, pharmaceutical and textile industries and so on. Ethanol and acetonitrile always exit as a mixture because of their directly or indirectly involvment in same production process. So in some pharmaceutical and chemical production, wastewater containing Ethanol and acetonitrile is often to be treated to recycle Ethanol and acetonitrile. But the mixture of Ethanol and acetonitrile can not be separated by conventional distillation, as they form azeotrope at atmospheric pressure, which will have a bad effect on the accuracy of distillation simulation to separate and purify the mixture.The pressure swing distillation of double columns was used to refine ethanol-acetonitrile mixture and high purity products of ethanol and acetonitrile were obtained simultaneously. Firstly, the azeotrope of Ethanol-acetonitrile mixture was measured from101kPa to500kPa and the result indicated that the azeotrope of Ethanol-acetonitrile mixture changed obviously with the change of pressure, the content of acetonitrile declined when the system pressure increased. Secondly, Ethanol and acetonitrile were separated by a series tower of pressurized column and atmospheric column under laboratory conditions, and the purity of ethanol and acetonitrile were more than99.5%which were in accordance with the calculated value by simulation. At the same time, reflux ratio was focused on to examine the influence on the experimental separation efficiency. The optimum reflux ratio of pressurized column and atmospheric column were3and4respectively.Furthermore, the simulation experimental data generated from Wilson, NRTL and UNIQUAC activity coefficient models was compared with the experimental data. The results show that the calculated values of boiling temperature by the Wilson, NRTL and UNIQUAC models have a good agreement with the experimental data, and the Wilson model gives a slightly better result.Finally, Aspen Plus software was applied to simulate the pressure swing distillation process of Ethanol-toluene system. Sensitivity analysis was applied to optimize the separation process in order to obtain the optimum process conditions such as operating pressure, theoretical plate number, reflux ratio, feeding position and circulating ratio. The final product was obtained with satisfactory purity and yield. The heat integration pressure swing distillation with traditional pressure swing distillation was also compared to analyse the energy consumption. The results show that the former saves power more than35percent.The industrial process of ethanol-acetonitrile mixture separation was designed. The specific parameters of the process were calculated through Aspen Plus.