重油催化裂化汽提过程的数值模拟

采用计算流体力学方法,建立了汽提段内待生剂吸附烃类物质的脱附和反应模型,耦合流动和传递模型,建立汽提过程流动-传递-反应的综合模型。采用该模型对一套工业重油催化裂化(RFCC)汽提段内的流动和反应状况进行了模拟计算,考察了待生剂上烃类物质的汽提反应过程,分析了化学反应对气固两相分布、气固速度分布、组分浓度分布和汽提效率等的影响,揭示了实际RFCC汽提过程中气固两相中各组分浓度的变化规律,并与文献值进行了对比。模拟结果表明,待生剂经汽提后约有3.86%(w)的烃类物质被汽提回收,汽提后仍有0.11%(w)的重油吸附在待生剂上进入再生器;进入沉降器的油气中仍含有35%(w)的重油,如何使催化剂上和气相中的重油组分充分反应是RFCC汽提过程优化的关键。

Numerical Simulation of Resid Fluid Catalytic Cracking Stripping Process

An desorption and reaction model for the hydrocarbons adsorbed on a spent catalyst in a resid fluid catalytic cracking(RFCC) stripper was established using the computational fluid dynamics method.Furthermore,an integrated model coupling the flow,transfer and reactions in the stripping process was obtained.Based on the model,the stripping and reactions in an industrial RFCC stripper were simulated.The influences of the chemical reactions on the distributions of solid volume fraction,gas and solid velocities,component concentrations,and stripping efficiency were investigated.The change rules of the every component concentrations in the gas and solid phases were revealed and compared with literature data.The results showed that after stripping,the recovered hydrocarbons was about 3.86%(w) based on the spent catalyst.There was still 0.11%(w) of heavy oil adsorbed on the spent catalyst which would enter regenerator.And the gas hydrocarbons entering disengager contained 35%(w) of heavy oil.Based on the simulation results,the importance of the full conversion of the adsorbed and gaseous heavy oil in the RFCC stripper was pointed out.