催化裂化管式待生剂分配器颗粒分配特性及内部流动特性的CPFD模拟

基于CPFD(Computational particle fluid dynamics)方法,对实验室前期研究的催化裂化管式分配器内的颗粒分配特性及内部流动特性进行了数值模拟,系统研究了输送风、松动风及分配器倾斜角度对颗粒分配不均匀指数的影响,并进一步考察了输送风和松动风对分配器各出口气体流量分布及内部气 固流动特性的影响。结果表明,增大输送风量、松动风量以及分配器的倾斜角度均可以降低颗粒分配不均匀指数,但改变松动风量的效果不如改变输送风量和倾斜角度显著。分配器倾斜角存在一个最优值时,颗粒分配均匀性最佳。输送风的增大会使得颗粒出料量最高的排料口的位置逐渐向分配器的末端移动,中间排料口所流出的气体流量占比增大,末端排料口排风量占比减小。引入松动风后,各出口的颗粒排料量更加接近,同时靠近末端排料口的气体流量占比明显增大。

CPFD Simulation on Particle Distribution and Inner Hydrodynamics in the Pipe FCC Spent Catalyst Distributor

Simulation on particle distribution and inner hydrodynamics in the pipe FCC spent catalyst distributor was carried out by using Computational Particle Fluid Dynamics (CPFD) method. The effects of flowrates of transport and fluidizing gases, distributor tilt angle on the heterogeneity index of particle distribution were studied, as well as the effects of flowrates of transport and fluidizing gases on the distribution of gas flow from the outlets and the inner two phase hydrodynamics. The results show that the heterogeneity index of particle distribution can be reduced by increasing the flowrates of transport and fluidizing gases, and the distributor tilt angle, in which the fluidizing gas has less impact than the transport air and distributor tilt angle. There is an optimized tilt angle at which the heterogeneity index reaches a minimum. With increasing of flowrate of transport air, the exit position with the highest particle flux gradually moves towards the end of the distributor, the fraction of gas flow from the middle exits increases, and the fraction of gas flow from the end exits decreases. After introducing fluidizing gas, the differences of solids fluxes at all outlets become smaller, and more gas flow from the outlets near the end of distributor.