Molecular Dynamics Simulation And Experimental Study Of Microwave Enhanced Separation Of Binary System

Microwave is a selective heating electromagnetic wave,which is often used in the field of chemical process strengthening.Among them,microwave as an separation agent for enhanced evaporation process has been a hot research topic.In recent years,it has been shown that microwave radiation can improve the separation efficiency by affecting the vapor-liquid equilibrium process of some binary system.However,the microscopic mechanism of microwave-enhanced separation of binary systems still lacking.To address the above issues,the aim of this paper is to investigate the microscopic mechanism of microwave-enhanced binary system separation by combining experimental methods and molecular dynamics simulation methods.To address the above issues,this paper aims to investigate the microscopic mechanism of microwave-enhanced separation of binary systems through a combination of molecular dynamics simulation methods and experimental methods.Meanwhile,a microwave-enhanced pilot distillation device was built to investigate the effect of microwave-enhanced distillation process for the separation of binary system.Firstly,the changes of liquid-phase microstructure,vapor-liquid interface microstructure and vapor-liquid interface properties of polar/nonpolar systems(ethanolbenzene,benzene-n-propanol)under the action of microwaves were investigated by using molecular dynamics simulation,and the microscopic mechanism of microwave-enhanced separation of binary system were discussed.The results show that the microstructure of liquid phase is almost unchanged and the microstructure of vapor-liquid interface is obviously changed under microwave irradiation.This indicates that the phase equilibrium of the binary system is changed because microwave radiation changes the properties of the vapor-liquid interface.In addition,the results show that the changes in intermolecular interaction forces and molecular orientation under microwave radiation are important factors affecting the phase equilibrium process.This provides theoretical guidance for an in-depth study of the microwave-enhanced separation binary system process.Then,the vapor-liquid phase equilibrium data of three binary systems(ethanol-water,ethanol-benzene and benzene-n-propanol)with different dipole moment differences at different microwave powers were measured in this paper.The results show that microwave radiation has almost no effect on the phase equilibria of ethanol-water system with small dipole moment difference,but has significant effect on the phase equilibria of ethanol-benzene system and benzene-n-propanol system with large dipole moment difference.For ethanol-benzene system,the molar content of ethanol in vapor phase was increased by microwave radiation.For benzene-n-propanol system,microwave irradiation reduces the molar content of n-propanol in vapor phase.This verifies the accuracy of the molecular dynamics simulation results,and provides basic data for further studies on the process of microwave-enhanced separation of binary system.Finally,the microwave was applied to a small pilot distillation unit,and the ethanol-benzene system was selected as the object of study.The single factor analysis method was used to explore the effect of microwave on the separation effect under different filler specific surface area,microwave power,reflux ratio and feed composition.The results showed that the increase of the specific surface area of the filler and the microwave power were both beneficial to improve the separation effect of the device.However,the increase of reflux ratio under microwave radiation reduces the mole fraction of ethanol molecules at the top of the tower.These studies provide the theoretical basis and basic data for further research on the separation of binary systems by microwave-enhanced distillation processes.