新型变径提升管冷模实验研究

以催化裂化平衡剂和常温空气为介质，在新型变径提升管冷模实验装置上考察了不同的操作条件对固体循环量及颗粒浓度轴径向分布的影响，并描述了扩径段内的流动结构。结果表明：固体循环量随着表观气速的增大而增大，随着伴床料位高度的增加而增大，且在改变进气比例时，循环量随着预提升气占比的增加而增大；与传统提升管相比，该新型结构提升管内部存在多种流型且扩径段内固含率有明显增加，底部扩径段内为密相湍流形态，固含率为0.3~0.4，上部等径段为稀相气力输送形态，固含率无明显变化，为0.05~0.1。新型变径提升管对斜管下来的催化剂起到了重新分配的作用，抑制了传统的“环-核”流动，使颗粒浓度径向分布更加均匀。

COLD MOLD STUDY OF A NOVEL DIAMETER-CHANGING RISER REACTOR

The effects of different operating conditions on the solid circulation and solid holdup distribution in the axial and radial directions of a novel diameter-changing riser were investigated in a cold-mold test using FCC equilibrium catalyst and room temperature air medium. The flow structure within the diameter expanded segment was described. Experimental results showed that the amount of solid circulation increases with the increase of the superficial gas velocity, and the bed height. When changing the ratio of intake air, the amount of circulation increases with the increase of the proportion of pre-lifting gas. Compared with the traditional riser, there are many kinds of flow patterns in the new structure riser, and the solid holdup in the expanded section is significantly increased. A dense phase turbulent flow pattern exists in the bottom region (εs is about 0.3—0.4) and a dilute phase pneumatic conveying form is observed in the upper region (εs is about 0.05—0.1) where the solid holdup has no obvious change. The novel variable diameter riser is able to redistribute the solid particles coming from the inclined pipe, resulting in inhibition of the traditional “ring-core” flow pattern, and making the radial distribution of solid holdup more uniform.