To improve the gas-solid two-phase mixing and eliminate the effect of secondary flow on the back-mixing near the riser wall in the feedstock injection zone

a novel fluidizer technology is proposed. A protective layer is produced by fluidizer to prevent long-duration contact between catalysts and feed near the wall. Three schemes for this technology (reverse-impact

concurrent-flow and crossed schemes) are used to improve the catalyst-feed mixing and back-mixing near wall by using 3-D CFD simulation. The amount of fluidizer of the optimal scheme is further optimized. The results show that the best is the reverse-impact scheme and the worst is the crossed scheme. The optimal reverse-impact scheme(when the mass flux of fluidizer is equal to the 15% mass flux of feed) can improve the catalyst-feed mixing

prevent the expanding of secondary flow and weaken the intensity of back-mixing at the |r/R|>0.9 near the wall.