Effect of flow patterns in the recirculation catalyst standpipe on the performance of FCC high-efficiency regenerator

ABSTR A C T In this work, the flow patterns of the recirculation catalyst standpipe in an industrial fluid catalytic crack-ing unit (FCCU) were investigated based on the dynamic pressure, and their effects on the regeneration process were analyzed. First, the dynamic pressure along the standpipe was systematically measured and used to determine the flow patterns. The results demonstrated that the frequency, amplitude, and stan-dard deviation of the dynamic pressure were correlated with various fluid patterns. Meanwhile, gas leak-age was detected near the slide valve. Based on the dynamic pressure behavior, two flow pattern models, which involved bubbling fluidized flow, transitional packed bed flow and packed bed flow, were estab-lished to interpret the impacts on the regeneration parameters. The results indicated that the developed model was consistent with precious observations regarding an industrial FCCU. This work contributes to a deeper understanding of the flow patterns in industrial luid catalytic cracking standpipes. (c) 2021 Elsevier Ltd. All rights reserved.