关键词: 提升管, 耦合反应器, 固含率轴向分布, 最大颗粒返混比

Abstract: A large scale cold model device of riser-fluidized bed compound reactor was set up based on the olefin reduction technology with auxiliary reactor for FCC naphtha upgrading. The axial distributions of pressure gradient and averaged cross-sectional solids holdup in the riser were measured using a multi-point pressure-density apparatus. The results show that the axial distributions of solids holdup in the riser are characterized by C type distributions with larger solids holdup value at the top and bottom sections, and smaller value in the middle section. The riser can be divided into three zones along the longitude according to the axial particles movement pattern, i.e., accelerating zone, full developing zone and back-mixing zone. The averaged cross-sectional solids holdup in the riser increases with the increase of solids overall circulating flux and decreases with the increase of superficial gas velocity. The static bed height of particles in the fluidized bed located at the exit of the riser has influence on the solids holdup in the back-mixing zone, but has little effect on the length of the back-mixing zone and the solids holdup below the back-mixing zone. Furthermore, empirical model for estimating the axial distributions of averaged cross-sectional solids holdup and the maximum back-mixing ratio of particles in the back-mixing zone was established based on the experimental data and theoretical analysis, respectively. The model predictions are in good agreement with the experimental data.

Key words: riser, compound reactor, axial distributions of solids holdup, maximum back-mixing ratio of particles