Numerical Research Of The Gas-solid Phase In Catalytic Cracking Short Contact Cyclone Reactor

The short-contact cyclone reactor is a new fluidized catalytic reactor which was developed based on a cyclone separator.Gas-solid two-phase flow of the cyclone reactor was simulated with the Euler– Euler model,and the gas-solid residence time distribution(RTD)in the reactor was studied by using species transport equation with no reaction.Firstly,the effects of model parameters and particle inlet parameters on numerical results were studied.The results showed that,compared with the mixing region,the separation region is effected more deeply by the specularity coefficient.The particle inlet parameters has only an influence on the inlet mixing region.Secondly,gas-solid residence time,extend of back-mixing and particle concentration distribution were analyzed in the mixing region with different configurations.Compare with the upwardly and straight tangential inlet configuration,the mixing region with downwardly tangential inlet configuration not only has the shortest residence time of gas and particle,but also generate the weakest extent of gas back-mixing.Compare with the downwardly cutting inlet configuration,the mixing region with downwardly tangential inlet configuration has more particle uniform concentration distribution.Finally,this paper analyzed the distribution of pressure,particle concentration and residence time in the optimized cyclone reactor.It could be drawn the conclusions that there is a noticeable axial pressure gradient in cylinder annular space with a radial pressure gradient in separation region.Increasing the inlet velocity within a certain range is helpful for gas-solid mixing.Bigger or higher density particles are more easily stacked near the wall of the cone,which also have more uneven particle distribution.In the cyclone reactor,the particle flow is close to plug flow,but the gas flow deviates from the plug flow.The mean residence time of gas and particle are less one second.The gas-solid flow patterns under different operating gas velocity are stable.The mean residence time of particle decreases with the increasing of gas velocity and increases with the increasing of particle mass flux.As the particle size or density increases,he particle flow is closely the plug flow and the mean residence time decreases.