关键词: 耦合流化床, 提升管, 固含率径向分布, 径向不均匀指数

Abstract: A large scale cold model experimental setup of a compound reactor mainly composed of riser and fluidized bed was established according to the olefin reduction technology with auxiliary reactor for FCC naphtha upgrading. The radial distribution of solids hold-up in the riser of the compound reactor was measured in different operating conditions by PV-4A optical fiber density apparatus. The experimental results show that the radial distribution of solids hold-up is the core-annular structure with lower solids hold-up in the center region and higher in the wall region. In the axial direction, the radial local solids hold-up gradually decreases in the particle accelerating region, tends to smooth in the fully-developed region, and then increases in the particle back-mixing region. The radial local solids hold-up decreases with increase of superficial gas velocity or decrease of solids flux. The static bed height of particles in the fluidized bed located atop the riser has effects on the radial distribution of solids hold-up in the back-mixing region, but has little effect on that of particle accelerating and fully-developed regions. The maximum solids hold-up in the particle back-mixing region appears to be close at the non-dimensional radial position f=r/R=0.7, and the axial distributions of radial local solids hold-up in different cross-sections in particle back-mixing region are not similar. According to the analysis of the radial non-uniformity index of local solids hold-up, the uniformity degree of radial distribution of local solids hold-up decreases in the following order: the fully developed region > the back-mixing region > the accelerating region. Furthermore, empirical model for estimating the radial distributions of local solids hold-up in the riser was established based on the experimental data and theoretical analysis. The error between the calculated data of the model and the experimental data is less than 6%.

Key words: coupled fluidized bed, riser, radial distribution of solids hold-up, radial non-uniformity index