CFD PRELIMINARY STUDY OF GAS-SOLID FLOW IN FCC CATALYST COOLERS

摘要

Heavy fractions of oil are converted into lighter ones in Fluid Catalytic Cracking (FCC) process. This process is important because lighter components are more valuable and useful. In FCC units, the catalyst is cooled in an external device called catalyst cooler, before returning to the riser reactor, to avoid carbon formation and consequent deactivation. Despite much has been done to improve the FCC reactor operation and to understand the gas-solid flow behavior inside it, there is a lack of information related to the catalyst cooler. Computational Fluid Dynamics Euler-Euler simulations were developed using Ansys FLUENT 14.5 to get information about gas-solid flow behavior in two different catalyst cooler geometries. For now, in a preliminary approach to evaluate the system, simulations have been developed without solids reentering the computational domain. As a consequence, a start-up particle bed was fluidized by air, which drags these particles upward the cooler. Our goal was to get information about the effect of geometric changes in gas-solid flow and fluidization inside the system. Despite the simple approach, results gave insights about the gas-solid flow behavior. The results obtained with these simulations indicated differences in the flow patterns for both geometries, showing the effect that the annular distributor has in gas-solid mixture and in the structure of the multiphase flow.