Study Of Scale-up Of Loop Reactor Of Hydrogenation Technology In Slurry-bed Based On CFD Simulation

In this paper,CFD method and Euler-Euler two-fluid flow model were applied to simulate and evaluate the effect of interface force model,liquid level height,bubble sizes and fluid physical properties on airlift loop reactor with a volume of 0.0785 m~3.The simulation results were tested and verified by comparing with experimental data.A gas-liquid two phase models was established based on the PBM-CFD coupled model and the Tomiyama drag force model,which could reduce the error to less than 10%and then agree well with experimental data.Therefore,local flow field information calculated by the CFD and bubble size distribution calculated by the population bubble model were optimized to describe gas-liquid complex flow more accurately.Experimental reactors selected included 100 t/a,1,000 t/a,100,000 t/a,500,000 t/a and1,000,000 t/a in term of throughput capacities of raw oil,corresponding reactor volumes were0.0095 m~3,0.00785 m~3,23.03 m~3,109.42 m~3 and 208.42 m~3 respectively.According to the established hydrodynamic model,the influence of the diameter ratio of the draft tube to the reactor,the height ratio of the draft tube to the reactor,the ratio between the installation height to the draft tube diameter,the nozzle angle and split draft tubes on flow behavior of airlift loop reactor was investigated.The simulation results showed that height-diameter ratio of the draft tube raised from 6 to 8 when maximum and distribution of gas holdup could be obtained,and then the ratio of installation heights of the draft tube to diameters was stable at 0.6;height-diameter ratio of the draft tube raised from 7.5 to 10.5 when maximum and distribution of liquid velocity could be obtained,and then the ratio of installation heights of the draft tube to diameters reduced from 0.8 to 0.6.As the nozzle angle increased from 30°to 90°,the gas holdup showed a slow increasing trend,and the liquid velocity reduced gradually with growing.Compared with the single-stage draft tube,the gas holdup increased by 10%,and the liquid velocity increased by 3%for the 0.0785 m~3 reactor.As the reactor becomed larger,the effect result of gas holdup and liquid velocity increased to 15%.Therefore,it was recommended that the design of nozzle angles should be in the range of 45°~60°depending on the circumstances,and choosing the draft tube divided into two segments towards the larger reactor,whose section position was located in the lower area of the draft-tube center.