Abstract: A new kind of feed injection scheme is put forward, in which the feed jets realize a countercurrent contact with the catalysts. The radial distributions of solids hold-up and particle velocity at different heights are investigated via a large-scale cold model. Moreover, the effects of pre-lift velocity and nozzle jet velocity on the flow features in the feed injection zone are analyzed. The feed injection zone can be further divided into three zones, the upstream transition zone (H=-0.675~-0.375 m), jet controlling zone (H=-0.375~0.375 m) and downstream transition zone (H=0.375~0.675 m). Compared with the conventional structure, the influencing region of jet is shortened obviously above the nozzles while extending below the nozzles. The radial concentration profile of the catalysts is more uniformly distributed in the initial contacting area of oil with catalyst. Then, empirical formulae for estimating the radial distributions of solids hold-up are set up based on the experimental data and theoretical analysis, the computed and experimental results are in good agreement.

Key words: catalytic cracking, riser, feed injection zone, solids hold-up, particle velocity

摘要： 在一套大型冷模实验装置中，考察了喷嘴射流与催化剂逆向接触的提升管进料段固含率和颗粒速度沿径向的分布及其对操作条件的影响，并与传统提升管进料段结构进行对比. 结果表明，沿轴向由下至上可将该新型结构的进料段分为喷嘴上游过渡区(H=-0.675~-0.375 m)、喷嘴射流控制区(H=-0.375~0.375 m)及喷嘴下游过渡区(H=0.375~0.675 m). 与传统形式相比，新型结构可使进料喷嘴安装截面以上射流影响区的高度明显缩短，喷嘴截面以下影响区域范围增大；油剂初始接触区域内催化剂沿径向的分布更均匀. 根据实验结果，得到新型进料段中射流控制区内典型截面固含率径向分布的经验模型，计算值与实验值吻合较好.

关键词: 催化裂化, 提升管, 进料段, 固含率, 颗粒速度