Phase Equilibrium And CFD Simulation On Vacuum Gas Oil Hydrogenation System

Vacuum gas oil is an important petroleum raw material.After decompression and distillation of crude oil,it is obtained with high sulfur,high nitrogen content and viscous quality.Hydrogenation process is an important technical to deepen petroleum processing and optimize the quality of oil products.It is one of the effective methods to deal with high sulfur content and poor quality.Therefore,studying the hydrogenation process of vacuum gas oil can effectively save oil resources and obtain better downstream products.The hydrogen(H2)used in the industrial hydrogenation system consists of new H2 and recycled H2,thus a small amount of methane(CH4)is mixed in the old H2.In this paper,the phase equilibrium of the vacuum gas oil hydrogenation system was studied,and the CFD simulation was carried out for the boiling bed reactor used in hydrogenation technology.It provides reliable data and theoretical support for the optimization design of vacuum gas oil hydrogenation and reactor in industry.First of all,the solubility of H2,CH4 and the mixed gas solubility in vacuum gas oil under high temperatures(353.15-453.15 K)and high pressures(1-7 MPa)were measured.The results showed that the solubility of H2 in vacuum gas oil increases with the increase of pressure,and decreases with the increase of temperature,and CH4 has the same rule.The relationship between henry constant H and temperature T is InH(MPa)=-413.05/T(K)+ 5.27 and lnH(MPa)=-990.67/T(K)+ 5.87 respectively.It is found that the mass transfer coefficient is positively correlated with pressure,that is,increasing the pressure is benefical to increase the solubility of gas in vacuum gas oil.The phase equilibrium of H2/CH4 gas mixture in vacuum gas oil was also been studied,and by calculating the selectivity found that the selectivity decreases with the increase of temperature.Furthermore,the solubilities of H2 and CH4 in vacuum gas oil were simulated by using COSMO-RS model,and the predicted results agree well with the experimental data.The ideal selectivity was predicted for the mixed gas,and also agree with the experimental selectivity well,indicating the reliability of the COSMO-RS model.In this paper,the CFD simulation on a new type of fluidized bed reactor was been studied.The pressure and velocity distribution and three-phase flow characteristics in the reactor were simulated by establishing the three-phase euler flow model.And the results showed that the three phases mixed completely,and the gas holdup is high in the reactor.In addition,three different types of baffles were also been simulated to explore which type of baffles is beneficial to the phase distribution.While the result shows that three phase distribution in the reactor with no baffle is better than any of the three types.