Particle Size Distribution And Three Phase Flow Simulation Of Polypropylene Loop Reactor

In this work,the particle size distribution and the characteristics of three-phase flow in the propylene polymerization loop reactor were studied base on a CFD-PBM coupled model.The model was divided by Gambit software,in which the conservation equation and turbulent equation was a discrete by Finite Volume Method.The SIMPLE algorithm has been employed to decouple the velocities and pressure.The main work and result of this research were as follows:1 ? The CFD-PBM coupled model which was based on Mixture model were used to simulate the particle size distribution in the propylene polymerization loop reactor.The comparison of the minimum transmission velocity and pressure drop values calculated by models and the experimental result show that the model was available.The result of particle size distribution in the loop reactor show that:(1)The detained range of particle at the bottom of the slurry reactor was less than the top,and detained badly in the 4th section of corner.(2)According to the comparation of the results calculated to the industry data from literature,the result simulated by CFD-PBM model were more accurate.(3)When the velocity of slurry was in the range of 6-12m/s,the detained range in the 4th section of corner decreases with the velocity of slurry.(4)Base on the comparation of the calculated results with the datas from factory,the particle in loop reactor have been impacted by both aggregation,breakage and growth.(5)As the turbulent dissipation increase,the diameter of particle in reactor tend to be unified.When solid holdup was low,the diameter of particle in reactor were respectively uniform,When solid holdup achieved over 4.5,the diameter of particle were reduce widely.2?Given the hydrogen as gas phase,the characteristics of multi-phases in the propylene polymerization loop reactor were studied.The result of simulation on muti-phases in the loop reactor show that:(1)The simulation result were in good agreement with the date from empirical formula,which indicate that the Euler-Euler model coupling with PBM model can simulate the muti-phases in the reactor.(2)When the slurry flow through the corner,the slurry velocityincrease from inside to outside on the radial section.(3)The solid holdup at the right position were larger on the radial of the reactor,but varied similarly in axial.(4)The turbulence energy on the radial section of the reactor presents "Two ends big,middle small" state,and each peak of turbulence energy appear in right section of rising pipe and left section of dropping pipe.(5)After adding hydrogen,the median particle diameter showed a significant reduction,but distribution range become smaller and tend to be uniform.Simulated on the diameter of particle in the propylene polymerization loop reactor and the multi-phase in the reactor had provide theoretical guidance for design and scale-up,which can prevent the efficiency of reactor when considerable saving the cost.