变径提升管反应器扩径段内气固流动特性研究

在变径提升管冷模装置上，以空气和催化裂化平衡剂为介质，考察了颗粒浓度的轴径向分布情况，并对扩径段内的微观流动特性进行了分析。结果表明，变径提升管内颗粒浓度整体上呈“上稀下浓”的分布形式，且沿轴向高度径向不均匀指数逐渐减小。与传统提升管底部相比，扩径段内颗粒浓度及间歇性指数显著增大，且沿径向分布更均匀，说明气固作用力显著增强，并且气固微观流动行为沿径向变化梯度减小。气固微观流动行为受反应器结构影响显著，变径提升管扩径段内气固流动行为类似湍流床，颗粒浓度波动幅度大，频率高，稀相和浓相分布相对均匀，有利于强化气固两相的接触及混合过程。

STUDY ON CHARACTERISTICS OF GAS-SOLIDS FLOW IN DIAMETER-ENLARGED SECTION OF A NOVEL RISER REACTOR

Axial and radial solid concentration profiles inside a novel riser reactor featured by bottom enlargement were investigated and the characteristics of gas-solid microflow behavior in the diameter-enlarged section were analyzed in a cold model apparatus. The results show that the solid concentration distributions are characterized by two regions: dense bottom region and dilute upper region with a reduced radial non-uniformity index along the axial direction. Compared with the bottom region of the conventional riser, higher solid concentration and intermittency index with more uniform radial distribution in the diameter-enlarged section are observed, demonstrating a stronger gas-solid interaction and a smaller radial gradient of the gas-solid microflow behavior. The gas-solid microflow behavior inside the diameter-enlarged section performs similarly to that in turbulent flow and is significantly affected by the structure of the reactor. The fluctuations of solid concentration in the diameter-enlarged section are characteristic of large amplitude and high frequency, and the distributions of dilute phase and dense phase are relatively uniform, which intensifies the gas-solid contacting and mixing process.