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.