工业环管反应器结构对非均匀流动的影响

摘要

工业环管反应器的结构参数对管内液固两相流动及装置的平稳高效运行具有重要的影响。对工业聚丙烯环管反应器进行 CFD 模拟，发现环管反应器中存在明显的非均匀流动现象——弯管处的颗粒偏析和直管处的颗粒带。进而引入非均匀度定量表征非均匀流动，研究直管段长度和直管段数量对非均匀流动的影响。研究发现，对直管段数量为2的环管反应器，当直管段高径比超过43时，出口截面上颗粒分布的非均匀度不随高径比增加而变化；对直管段数量为4的环管反应器，直管段高径比越大，出口截面上颗粒分布越均匀；对直管段长度为39 m、高径比为65的环管反应器，直管段数量越多，出口截面上颗粒分布越均匀；与直管段数量相比，直管段长度（高径比）对出口处非均匀度的影响更显著。研究结果可为工业环管反应器的设计和优化提供指导。%Liquid-solid flow and stable operation of a loop reactor were affected by the reactor’s structural parameters. CFD simulation of the industrial polypropylene loop reactor showed clear non-uniform flow phenomenon with segregation at bend and particulate rope in straight tube. Hence, the non-uniform flow under different straight tube height/diameter ratios and straight tube number was quantitatively analyzed by introducing a non-uniformity parameter. Simulated results indicated that non-uniformity of particulate distribution at 2-leg loop reactor’s outlet did not change after the height/diameter ratio exceeded 43. The flow uniformity of particulate distribution at 4-leg loop reactor’s outlet kept increasing with larger height/diameter ratio. When the height/diameter ratio was fixed at 65 and height of the straight tube was kept at 39 m, flow uniformity of particulate distribution at the outlet was improved with more straight tubes. But, the influence of the height/diameter ratio on the outlet’s non-uniformity was more significant than that of straight tube number. The research results could provide guidance for design and optimization of industrial loop reactors.