关键词: 预提升结构, 固含率, 颗粒速度, 径向不均匀指数

Abstract: Solids volume fraction and particle velocity in the pre-lifting structure with two strands of catalyst inlets were studied using optical fiber on a large scale cold model experimental setup. A radial non-uniformity index was applied to describe quantitatively radial distribution of solids volume fraction and particle velocity. The experimental results in different pre-lifting structures were compared. The experimental results show that the pre-lifting structure can be divided into three zones. According to the analysis of radial non-uniformity index of solids volume fraction and particle velocity, the uniformity degree of radial distribution of solids volume fraction and particle velocity decrease in the order of riser region > bottom region > central tube region. The homogeneous distributions of solid volume fraction and particle velocity exist on one section between 1.3 and 2.3 m in the riser. Compared with the pre-lifting structure without central tube and traditional structure, the distribution of solids volume fraction is so homogenous that catalyst particles and oil can react more effectively. Then, empirical models using parameters of terminal solid volume fraction es', Froude number Fr and axial height/riser diameter h/Dr for estimating the axial distributions of averaged cross-sectional solids volume fraction in the pre-lifting structure are obtained based on the experimental data and theoretical analysis, respectively, which agree well with the experimental data.

Key words: pre-lifting structure, solids volume fraction, particle velocity, radial non-uniformity index