关键词: 耦合流化床, 固含率, 轴向分布, 流动特性

Abstract: The axial distributions of cross-sectional averaged density of FCC particles were measured in a large scale cold model turbulent fluidized bed-riser coupled reactor. The results showed that the flow behaviors of FCC particles in the coupled reactor presented fairly different characteristics with changing of superficial gas velocity. The flow behavior could be divided into three types based on superficial gas velocity. A steady flow was observed in the reactor for superficial gas velocity below 0.58 m/s, while a back-mixing zone in the top of the riser appeared as the superficial gas velocity varied between 0.7~1.04 m/s. When superficial gas velocity was greater than 1.16 m/s, the riser concentration reforming and accelerating zones occurred in the bottom of the reactor, with the fully developed zone appearing in the middle of the reactor, and the back-mixing zone was enhanced in the top of the reactor. The cross-sectional averaged density increased with the increase of superficial gas velocity. The static bed height had no obvious effect on the axial local solids hold-up in different cross-sections. The critical superficial gas velocity responsible for the appearance of the riser concentration reforming zone was smaller for the higher static bed height than that for the lower static bed height. Furthermore, an empirical model for estimating the axial distribution of averaged cross-sectional solids hold-up was established based on the experimental data and theoretical analysis, respectively, which agreed with the experimental data.

Key words: coupled fluidized bed, solids hold-up, axial distribution, flow behavio