Abstract:

The matching between oil and catalyst in a downward pointed feed injection scheme was investigated in a large scale model cold riser. Two new parameters were introduced as relative concentration of feed jets and that of catalyst particles, which an oil/catalyst matching index was calculated from the concentration distributions of feed jets and catalyst particles. Experimental results showed that the downward pointed feed injection quickly covered the whole cross section of the riser and significantly shortened the mixing height of oil and catalysts such that the feed oil and the catalyst particles could contact rapidly and uniformly. According to axial distributions of the oil/catalyst matching index, the feed segment under the proposed new scheme of feed injection were divided into three regions, i.e. the initial contact region, the gas-solid diffusion region and the recovery region. A better matching between oil and catalyst could be obtained through a lower nozzle setting angle α, a higher prelift gas velocity U_r and a moderate jet gas velocity U_j. The optimal operating condition was U_r=4.1 m·s^-1, U_j=64.2 m·s^-1 and α=30°. Furthermore, the simulation of axial distribution of the average oil/catalysts matching index were performed by combination with experimental data, which could certainly provide some guidance for the design of downward pointed feed injection scheme.

Key words: riser, feed injection zone, two-phase flow, mixing, oil/catalyst matching index

摘要：

通过大型冷模实验，引入射流相对浓度及颗粒相对浓度两个新参数，考察了油剂逆流接触新型提升管进料段内的油剂“匹配”状况。结果表明，喷嘴向下倾斜的进料方式能够强化油剂初始接触区域内两相混合，混合区高度可缩短约1/3。根据进料段内油剂匹配的特点，可将该新型进料段分为油剂初始接触区、气固扩散区和过渡恢复区3个部分。根据实验结果，得到了较佳的工况组合，分别为：喷嘴与轴向夹角α=30°，预提升气速U_r=4.1 m·s^-1，喷嘴气速U_j=64.2 m·s^-1。结合实验数据，对新型进料段中油剂匹配指数的轴向分布进行了拟合，结果可为油剂逆流接触提升管进料段的工业设计提供参考。

关键词: 提升管, 进料段, 两相流, 混合, 油剂匹配指数