CPFD Simulation Of Spent Catalyst Distributors In Fluid Catalytic Cracking Units

The development of the regenerator in the industrial oil refining plant makes it more important to develop a highly efficient spent catalyst distributor to solve the problem of distributing homogeneity in the regenerator.At present,the research on the dispenser is mainly focused on the patented technology developed.The existing experimental study on the spent catalyst distributor can measure the distribution uniformity of the particle,but it is not easy to measure the internal gas-solid flow pattern in the distributor.In the present research,numerical simulation for are CFD simulation method of the two-fluid model,taking them quite a quasi fluid phase,which can't accurately reflect flow characteristics of the actual particle.Barracuda simulation software was used to study gas-solid flow characteristics on pipe distributor and boat distributor developed in the laboratory.First suitable geometric model and drag force mode were concluded by comparing with the experimental results.Furthermore,the effects of different operation parameters(transport gas volume,aeration gas volume and inclination Angle)on the gas-solid flow uniformity of the spent catalyst distributor were discussed.Finally,the parameters of each outlet and the distribution of the flow field are analyzed.The results show that CPFD predict reasonably:(1)The increase of the transport gas velocity and aeration gas velocity can reduce the particle inhomogeneity index of the pipe distributor and the boat distributor.(2)For the pipe distributor,the outlet with the maximum mass flow rate of a particle at any transport gas velocity,and the position of the outlet will be far away from the particle inlet with the increase of the transport gas velocity.For the boat distributor,no matter the transport gas velocity and the aeration gas velocity,the particles are mainly discharged from the previous four outlets.The study also find that:(1)For pipe distributor,the transport gas is mainly distributed in the upper part of the distributor and outflow from both ends.For these two kinds of distributors,the transport gas increases,the particle concentration decreases,the particles moving backward are more and more,and the fluidized dead zone decreases and moves backward at the same time.(2)For these two kinds of distributors,the area of the particle concentration and the fluidized dead zone was greatly reduced after the aeration gas,but there was little change in the particle volume fraction between the gas holes.(3)For these two kinds of distributors,the increase of inclined angle can also reduce the inhomogeneity index of particles.And with the increase of the inclined angle,the particle velocity is smaller than that of 0.1 m/s,and the position of the fluidized dead zone is closer to the end of the distributors.But not in any case,the bigger the better the better,and there's an optimal inclined angle in the middle.(4)In the same working condition,the performance of the pipe distributor is better than that of the boat distributor from the particle inhomogeneous index,particle concentration,particle outlet mass flow rate and fluidized dead zone.