气固催化反应流动的CFD-DEM模拟研究  

CFD-DEM simulation of gas-solid reacting flows in catalytic reactor

作　　者：吴昌宁[1] 丁宇龙[1] 金涌[1] 程易[1] 

机构地区：[1]清华大学化学工程系,北京市绿色反应工程与工艺重点实验室,北京100084

出　　处：《中国科技论文在线》2008年第12期897-904,共8页

基　　金：国家自然科学基金(20306012;20806045);高等学校博士学科点专项科研基金(20050003028)

摘　　要：针对复杂气固催化反应流动系统,提出一种新的气固催化反应流动的模型框架,即CFD-DEM反应流模型框架,计算流体力学(CFD)方程用于描述气相的流动和传递行为,离散单元法(DEM)用于描述颗粒相的运动。结合石油催化裂化(FCC)过程,考虑颗粒间传热和气固相间传热模型、催化剂颗粒瞬态失活模型以及FCC过程的4集总动力学模型,建立完整的CFD-DEM反应流模型。应用所建模型模拟在不同剂油比操作下高2m,宽0.05m的二维提升管和下行式反应器内的FCC过程。由于能实时追踪各个催化剂颗粒的运动、传热和化学反应行为,模拟结果直接揭示了不同的流动结构和颗粒返混行为对反应器性能(如汽油、焦炭等产物的选择性)的影响。此外,方法论本身可推广至FCC过程以外的气固相催化或非催化过程的精细描述。An extended CFD-DEM coupled approach is used to simulate the complex gas-solid reacting flows in fluid catalytic cracking （FCC） processes accommodated in riser reactor in a transient manner.Considering the solid catalyzed gas-phase reactions,the model particularly incorporate the descriptions for heat transfer behaviors between particles and between gas and particles,the instantaneous catalyst deactivation,and the lumped kinetics in the gas phase for FCC process,together with the transport equations for the gas phase.The presented model is applied to investigate the FCC processes in a riser and another downflow reactor,both of which are two-dimensional,2m in height and 0.05m in width.The distinct advantage of the present approach is that the catalyst activity can be calculated in time by tracking the history of the particle movement with the occurrence of heat transfer and chemical reactions.The simulation results capture the major features of FCC processes very well.The reduced selectivity to the desired intermediate products in the risers,especially under the operations of high catalyst-to-oil ratio,can be clearly understood from the simulated clustering phenomenon and backmixing behavior of catalyst particles.It can be concluded that this type of modeling approach forms a solid basis for the cross-scale modeling of general gas-solid two-phase catalytic reacting flows.

关 键 词：化学反应工程 反应流模拟 CFD-DEM 气固催化反应器 催化裂化 催化剂失活 

分 类 号：TQ032[化学工程]