Structure Optimization And Multiphase Transfer Performance Simulation Of Trickle Bed Reactor

Due to the increasingly strict requirements of automobile gasoline standards in China,the gasoline feedstock must be hydrodesulfurized before it is put into use.The structure of the components in-the reactor has a great influence on the performance of the reactor.The purpose of this paper is to propose the structural design of a new Venturi gas-liquid distributor to solve the problems existing in the traditional gas-liquid distributor,and establish the multi-phase reactor model of the actual size industrial trickle-bed reactor.For this purpose,this paper is based on the existing gasoline hydrodesulfurization reactor technology.The simulation and research were carried out at the single tube scale of the gas-liquid distributor,the inlet distributor,the gas-liquid distribution plate scale and the hydrodesulfurization reactor scale respectively.The results showed that:Compared with similar dispensers,the performance of Venturi gas-liquid dispensers in this paper was better.The multiphase reactor model established in this paper could describe the actual industrial hydrodesulfurization reactor,which is of reference value for the optimal design of such reactors.Firstly,in the single pipe scale of gas-liquid distributor,this paper carried out simulation calculation for the traditional overflow type and suction type gas-liquid distributor.Aiming at the problems of central confluence and uneven liquid distribution existing in the traditional gas-liquid distributor,a structural design of a Venturi gas-liquid distributor was proposed.Based on CFD simulation,the distribution uniformity,pressure drop and residence time distribution of the divider were investigated,and the structure and performance of the divider were optimized.The results showed that the improved venturi effect applied twice in the Venturi gas-liquid distributor displayed better performance than the similar distributor,and significantly enhanced the gas-liquid mixing degree.Secondly,at the scale of the inlet distributor and the gas-liquid distribution plate,the actual physical model in industry was built according to the actual size.The simulation of the inlet distributor and the gas-liquid distribution plate was carried out,and the influence of the structure of the inlet distributor and the gas-liquid distribution plate on the fluid distribution performance was studied.It was found that the structure of inlet distributor and gas-liquid distribution plate in the reactor directly affected the initial distribution of raw materials in the implantation layer,and the optimal design of internal components could significantly improve the performance of the reactor.Finally,at the scale of hydrodesulfurization reactor,the flow,heat transfer and reaction performance of gasoline hydrodesulfurization reactor of 600,000 tons/year were studied based on CFD simulation.Under full consideration of interphase drag force and capillary force,a complete and accurate mathematical model was established by using porous media theory.The reliability of the model was verified by comparing with the experimental and simulation results in the literature.The complicated oil and gas flow,heat transfer,mass transfer and reaction process in the hydrodesulfurization reactor were analyzed comprehensively and systematically.It was found that the distribution of component concentration in the reactor is directly related to the distribution of flow,pressure and temperature.Under the operating conditions of a pressure of 2 MPa and an inlet temperature of 238?,the desulfurization rate of the reactor was about 94%,which can meet the requirements of industrial desulfurization.This paper also revealed the basic characteristics and laws of the complex oil and gas flow,heat transfer,mass transfer and reaction process in the industrial hydrodesulfurization reactor,which provided theoretical support for the optimal design of the reactor.