Distribution of Solid Holdup and Particle Velocity in a High Density Gas-solids Circulating Fluidized Bed Downer
1. State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
2. Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
Abstract：In order to investigate the distribution characteristics of solid holdup and particle velocity in the downer to determine the conditions for high-density operation, the axial and radial distributions of particle concentration and velocity were measured under different apparent gas velocity (Ug) and particle circulation rate (GS) in a self-built setup of gas-solid downer (total height 18 m, downer height 8 m, diameter 80 mm). The results showed that the entire downer was operated with high density conditions with solid holdup up to 0.12 when solids flux up to 700 kg/(m2·s). Radial distribution of solid holdup in the downer was affected significantly by inlet structure. Near the downer inlet, solid holdup was higher in the center and decreases towards the wall. For axial distribution of solid holdup, it is higher in the bottom and gradually decreases along the downer, which showed development of the gas-solid flow structure. For particle velocity distribution it is found that particles were accelerated near the downer inlet and then flow downward with constant velocity when particle circulation rate was smaller [100 kg/(m2·s)], and the cross-sectional averaged particle velocity increases obviously with the increase of superficial gas velocity. While solids flux increases up to 500 kg/(m2·s), changes of particle velocity was sight with the changes of superficial gas velocity, and radial distribution of particle velocity was more uniform near the downer inlet than that at other axial locations, it was showed that downer inlet has significant effects on gas-solids flow.
WANG Chengxiu1,LI Jingya1,SU Xin1 et al. Distribution of Solid Holdup and Particle Velocity in a High Density Gas-solids Circulating Fluidized Bed Downer[J]. 化学反应工程与工艺, 2020, 36(1): 17-25.
