关键词: 提升管, 进料段, 两相流, 混合, 油剂匹配指数

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