Study On Separation Process For Isopropanol-ethylene Glycol Dimethyl Ether Mixture

Isopropanol and ethylene glycol dimethyl ether are important chemical raw materials.The mixture of isopropanol and ethylene glycol dimethyl ether is produced during the synthesis of different intermediates by pharmaceutical company,which needs to be separated for recycling and reusing.However,the boiling points of these two components in atmospheric condition are very close,it is difficult to obtain high purity products by simple distillation.In this paper,NRTL model is selected to study the system through the study on thermodynamics.At first,this paper proposed pressurized distillation and extractive distillation to analyze the separation of the mixture.For pressurized distillation,the relationship between pressure and boiling point and the effect of pressure on vapor-liquid equilibrium of binary system were analyzed and chose 5.0 atm as suitable operating pressure.For extractive distillation,ethylene glycol was selected as the extractant.PRO/II software was used to simulate distillation process,the process parameters were optimized with the separation effect and energy consumption as the target parameters,then the optimum operating conditions of pressurized distillation and extractive distillation were obtained respectively.Meanwhile,the influence of water content on the separation effect of these two distillation processes was analyzed,the increase in water content was not conducive to the separation of the mixture,and water content had a greater impact on the separation effect of pressurized distillation.When the water content reached a certain degree,the above two distillation processes were no longer applicable.Reactive distillation was considered for analysis.Direct hydration reaction of ethylene oxide was used as an auxiliary reaction to achieve dehydration.Aspen Plus was used to simulate reactive distillation process,the process parameters were optimized to obtain optimized operating conditions.For the mixture with less water,the pressurized distillation was selected,its separation effect was good.Compared with the simulation calculation results of the extractive distillation,it was found that the energy consumption of pressurized distillation was 31.3% lower than that of extractive distillation because the third component was not added.In the pharmaceutical industry,an actual pressurized distillation device was set up to separate the mixture,the mass fraction of isopropanol in the top product was above 98.0% and the mass fraction of ethylene glycol dimethyl ether in the bottom product was above 99.5%,which met the requirements for recycling.At the same time,it was found that the simulation results of the NRTL model were similar to the actual separation results,while the simulation results of the UNIFAC model were quite different from the actual results.