Erosion Prediction in FCC Unit of Refinery Through Computational Fluid Dynamics Simulation

Abstract

Abstract In the Fluid Catalytic Cracking unit of refinery, erosion due to catalyst impact on wall refractories is a serious issue that affects the plant performance. In the present study, Computational Fluid Dynamics (CFD) coupled with Discrete Element Model (DEM) method is used to characterize gas-solid flow dynamics and erosion in regenerated catalyst slide pipe (RCSP). Catalyst particles size in the range of 1-180 µm were considered for the simulations. The predicted erosion profile was verified by comparing with thermography experiments and were found in a good agreement. The predicted results revealed that due to partial opening and orientation of regenerated catalyst slide valve, the rapid alterations of flow direction of catalyst particles take place. Particles recirculate in the rear end of the pipe and continuously impinges at the 12 o'clock position upstream of the valve. This led to erosion in the pipe. The experimentally validated CFD model was used to characterize the erosion profile under different relative openings of regenerated catalyst slide valve (RSCV). It was observed that with increasing the valve opening the erosion profile was reduced due to decreases catalyst recirculation velocity and vice-versa. Further, effect of valve opening orientation was also studied and it was found that by changing the valve opening orientation from parallel to ground surface to down towards, erosion was not observed due to small recirculatory flow of catalyst with low velocity. The results presented in this work will help refiners to understand the catalyst flow dynamics inside the regenerated catalyst slide pipe, root cause of erosion in pipes, and to achieve further improvements in the performance of plant.