Effects of different operating conditions on the distributions of the particle concentration and probability density in axial and radial sections as well as on the gas-solids contact efficiency in the pre-lifting section were investigated in a cold model apparatus with a bottom-enlarged section and multiinjections riser using FCC equilibrium catalyst and room temperature air as test mediums.Results showed that compared with the gas-solid flow characters in different pre-lifting axial regions,the flow behavior is significantly affected by gas in the bottom inlet region and the upper necking region;the particle concentration,the radial distribution uniformity and the gas-solids contact efficiency are all reduced.While in the central development region,the gas-solid contact efficiency is higher with a better particle concentration distribution.While compared with the traditional equal diameter pre-lifting structure,the gas-solid flow behavior in the diameter-enlarged pre-lifting section is similar to that in the tur bulent bed,the particle concentration and uniformity of the radial particle concentration distribution is significantly improved,the gas-solid separation phenomenon is effectively suppressed due to violent gassolid turbulent motion and higher gas-solid contact efficiency,which lead to an intensified gas-solid contact and mixing process.%以催化裂化平衡剂和常温空气为介质,在多层进气底部扩径提升管冷模实验装置上,考察了不同操作条件对预提升段内颗粒浓度轴径向分布、概率密度分布及气固接触效率的影响.结果表明:对比预提升段不同轴向区域气同流动特性可以发现,在底部入口区和上部缩颈区,流动行为受气体影响较大,颗粒浓度、径向分布均匀性及气固接触效率降低,中部发展区气固接触效率较高,颗粒浓度的分布效果较好.与传统等径预提升结构相比,扩径预提升段内气固流动行为类似于湍动床,颗粒浓度显著提高,径向颗粒浓度分布的均匀性得到明显改善,气周分离现象得到有效抑制,气固湍动剧烈,接触效率高,有利于强化气固两相的接触和混合过程.
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