摘要
提升管进料混合段是催化裂化提升管反应器最关键的区域。为找到一种合理的方法以改善提升管进料段内油剂两相流动及混合状况,采用了EMMS曳力模型,对提升管进料混合段气固两相流混合及流动进行三维计算流体力学(CFD)模拟,并与实验数据进行了对比;分析了气固两相流动及混合特性,还模拟分析了不同进料角度对提升管进料混合段内二次流的影响以及两相流动、混合状况。结果表明,EMMS/Matrix曳力模型能够较为准确地模拟进料混合段内气固两相流动、混合过程;当喷嘴斜向上喷射进料时,射流影响区颗粒流混合不均匀,颗粒流恢复稳定流型所需时间长,且边壁受二次流影响,出现"高浓度、高返混"区域,工业过程中易引起结焦。由此提出了一种新型提升管进料段结构的改进方案,能合理利用二次流,实现颗粒流均匀混合和流动。
Feedstock injection zone is the most critical area for fluid catalytic cracking （FCC） riser reactor. The 3-D computational fluid dynamics （CFD） simulation of gas-solid two-phase mixing and flow in this zone was performed by an energy-minimization multi-scale （EMMS） drag model. The dynamic behavior of the mixing and flow was discussed by comparing the simulation results with experimental data. Moreover, the two-phase mixing and flow in different feedstock injection structures with various angles of feedstock nozzles relative to the axes of riser reactor were simulated. The gas-solid inhomogeneous mixing and the secondary flow were analyzed. The results show that the behaviors of gas-solid two-phase mixing and flow in the feedstock injection zone can be depicted well by the EMMS drag model. Furthermore, when the angles of the feedstock jet up to the riser, it will be appeared that the gas-solid two-phase mixing sufficiently require more time to reach the steady flow. The cluster together and back mixing of a large number of particles in the vicinity of riser wall are inevitable, which results in the coke in industry. Finally, a novel way is proposed to realize gas-solid two-phase uniform mixing and flow as well as to control the secondary flow reasonably.
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2014年第1期71-78,共8页
Chemical Reaction Engineering and Technology
基金
国家重点基础研究发展计划(973计划)(2012CB215000)
关键词
催化裂化
进料段
喷嘴
提升管反应器
曳力模型
计算流体力学
fluid catalytic cracking
feedstock injection structure
nozzle
riser reactor
drag model
computational fluid dynamics
