Performance Analysis And Optimization Of Epoxidation Of Ethylenein In A Tubular Fixed Bed Reactor

Ethylene epoxidized to produce important industrial chemicals such as ethylene oxide is the main chemical product method in modern times.On one hand,the optimization of production processing is the preparation of the silver catalyst.On the other hand,the optimization is operating of the reaction device.For the large amount of preparation and research of the silver catalyst,the industrial application research of the synthetic reactor is relatively weaked.Leading the space of the independent research and development of the silver catalyst is limited which is caused by the foreign monopoly companies.Based on the domestic YS-M series of silver catalysts,the two-dimensional homogeneous phase model of tubular ethylene epoxidation reactor,investigated the effects of air velocity,reaction inlet temperature,reaction pressure and molar fraction of reaction inlet material on the performance of epoxidation reactor.The industrial matching degree of the agent lays the foundation for both optimization.Based on differential equilibrium,two dimensional homogeneous mathematical model of a tubular fixed bed ethylene epoxidation reactor was constructed,and the Fortran90 program was compiled.The validation analysis shows that the simulation results of the reactor mathematical model are well compatible with the data collected from industrial production,and are suitable and reliable.Based on the model,the effects of ethylene epoxidation conditions on reactor performance were systematically simulated and analyzed.The results show that,(1)With the air velocity increasing(4000 hr-1～4600 hr-1),the temperature of the bed layer,the radial temperature difference and the concentration of the main and secondary products all gradually decreasing,the hot temperature of the bed layer moves to the inlet direction of the reactor,and the selectivity of EO,the production strength and the production capacity gradually increased.(2)The inlet temperature of the reactor(150 ℃～250 ℃)has little effect on the catalyst bed’s temperature,the selectivity of EO decreases slightly and the production capacity and strength are increased.(3)The concentration of ethylene increased(20%～35%),the bed temperature and the radial temperature difference increased,the hot temperature moved to the entrance direction,and the selectivity,production capacity and strength of ethylene oxide increased.While the increase of oxygen concentration(7%～8.5%),the catalyst bed temperature,radial temperature difference and hot spot temperature obviously increased,the selectivity of EO decreased slightly.(4)the reaction pressure increased(1.8 MPa～2.1 MPa),the bed temperature,the radial temperature difference,the concentration of the by-products increased,the selectivity of epoxy ethane.Catalyst production intensity and production capacity gradually increased.The sensitivity analysis of reactor tubes’ diameter and the optimization of tube diameter were carried out for domestic YS-M silver catalyst.The results showed that when the tube diameter increased(35 mm to 40 mm),catalyst bed temperature,hot spot temperature,radial temperature difference increases and the hot spot temperature moves towards the outlet of the reactor.The concentration of the main and by-product,the pressure of the bed layer increases.The selectivity of ethylene oxide decreased and the production capacity of the catalyst increased.From the requirements of catalyst loading and activity to the stability conditions of reactor,the optimized tube diameter ranges from 34.4 mm to 39.8 mm in theory.From the viewpoint of technology and economy of chemical industry,the optimum pipe of tubular ethylene oxide reactor is determined to be 36 mm～39.8 mm.