Mechanism And Application Study Of The Effects Of Microwave Irradiation On The Relative Volatility Of Binary Mixtures

After two hundred years of development,distillation technology has become the most important separation technology in chemical industry,and has been widely used in industrial production process.Now optimizing distillation technology,realizing energy saving and emission reduction of separation process becomes a popular topic in the research of distillation separation process.The special effect of microwave on the material was used to explore the influence mechanism of microwave field on the relative volatility of binary system in this paper,and the influence was first applied to the process of enhanced evaporation separation.The microwave enhanced evaporation separation technology,which expect to be used to separate some special systems,was developed.In this paper,the dew point of pure substance in the microwave field was studied,and the dew point of the pure substance under different microwave powers was obtained.The results show that the dew point of the pure substance has no obvious change under different microwave powers.Study on the effect of microwave on the relative volatility of binary system was conducted subsequently.The relative volatility of three binary mixtures in nonequilibrium steady state(namely,cyclohexane-isopropanol,cyclohexane-ethanol,and ethanol-isopropanol)were measured under different microwave irradiation powers.The experimental data were compared with the conventional heating experimental data.The results showed that the relative volatility of cyclohexane in the cyclohexaneisopropanol system decreased when the microwave power increased by comparing with conventional heating method.For the ethanol-isopropanol and ethanol-cyclohexane systems,microwave irradiation had no significant impact on the relative volatility of ethanol.The conclusion that the different effect of microwave on different systems is mainly due to the following points: Microwave only has an effect on the relative volatility of the polarity-non polarity binary system with large difference in dielectric properties.Microwave can greatly accelerate the mass transfer process of polar molecules,and reduce the relative volatility of nonpolar substance when the boiling point of the polar component is higher than that of the nonpolar component.The weaker the intermolecular force of polar molecules,the more obvious the changes in relative volatility of the system under microwave irradiation.Finally,the microwave falling film evaporation separation process of cyclohexane-isopropanol system was studied.In this paper,the microwave and falling film evaporation separation was firstly coupled,and the effect of different microwave powers on the separation efficiency was explored.The results showed that microwave irradiation can promote the evaporation of isopropanol,and reduce the mole fraction of isopropanol in the liquid phase.It indicates that microwave can change the direction of separation for the cyclohexane-isopropanol system.The results could provide a new solution for separation process of special composition system.