Abstract: An external catalyst cooler is used to remove extra heat to ensure the heat balance in the system of fluid catalytic cracking (FCC). However, the single inlet in the cooler is difficult to make the catalysts distributed uniformly in the inlet region. Moreover, the catalysts streaming deviate from the original flow direction due to effect of valve plate. These influence their long period of stable operation. A pilot scale cold mode experimental device was built to study and optimize the catalysts distribution and deviation of flow direction in the inlet region of the external catalyst cooler. The effect of operation conditions on catalysts distribution and deviation of catalysts flow direction was measured. And two new inlet structures were designed to improve the non-uniform flow and deviation of catalysts flow direction. The experimental results showed that for the original inlet structure used in industry, the non-uniform distribution of the catalysts was first increased and then decreased with increasing the solid mass flux (Gs) in inlet tube. The worst circumferential distribution of catalysts occurred at Gs=230~620 kg/(m2?s) and ug=0.2~0.35 m/s. The deviation of catalysts flow direction was determined by locally asymmetric distribution index. The index increased and then decreased as the solid mass flux increased. The maximum value was presented at Gs=380~720 kg/(m2?s). After installing two new inlet structures, the catalysts mass distribution in the inlet region of the external catalyst cooler got more uniform and the deviation of catalysts flow direction was weakened. The inlet structure 2 had better optimization effect on mass distribution and symmetrical distribution of catalysts. Pressure drop in inlet tube with structure 2 increased by about 0.14 kPa compared to that of the original inlet structure.

Key words: external catalyst cooler, inlet region of catalyst, circumferential distribution, asymmetrical distribution, optimization

摘要： 外取热器是维持催化裂化反应?再生系统热量平衡的关键设备，在其入口区域内催化剂质量呈现非均匀分布，加之入口管路内安装的调节阀门使催化剂流动出现偏流，影响其稳定运行。在一套大型冷模实验装置上，系统考察了入口区域催化剂质量分布特性和催化剂流动的偏流特性。结果表明，对于工业采用的初始入口结构，随入口管路内催化剂质量流率增大，催化剂质量周向分布非均匀性先增强后减弱，当Gs=230~620 kg/(m2?s), ug=0.2~0.35 m/s时，催化剂的质量周向分布均匀性最差；随入口管路内催化剂质量流率增大，催化剂流动偏流程度先增加后降低，在Gs=380~720 kg/(m2?s)时，催化剂流动偏流最显著；通过设计安装入口结构1和入口结构2，入口区域的催化剂质量分布均匀性得到了显著提升，催化剂流动偏流也被大幅弱化；入口结构2的优化效果更明显，其入口管路压降较初始入口结构升高约0.14 kPa。

关键词: 外取热器, 催化剂入口区域, 周向分布, 非对称性分布, 优化