MP-PIC simulation of the effects of spent catalyst distribution and horizontal baffle in an industrial FCC regenerator. Part II: Effects on regenerator performance

Abstract

Improving distribution uniformity of spent catalyst and adding horizontal baffles are two effective measures to improve the regeneration performance of a fluid catalytic cracking (FCC) unit. In this study, the effects of the spent catalyst distribution and horizontal baffle on the regeneration performance of an industrial coaxial compact FCC regenerator is simulated using an Eulerian-Lagrangian multi-phase particle in cell (MP-PIC) method with coupled hydrodynamic and coke-burning kinetics models. The coke-burning kinetics model developed by Arbel et al. (Ind Eng Chem Res, 1995, 34(4): 1228–1243) is used in the simulation. The MP-PIC simulations successfully predicted agreeable temperatures in the industrial regenerator. Serious afterburning in the freeboard was also successfully predicted. The effectiveness of the two intensification measures in enhancing the performance of an industrial FCC regenerator were proved, as indicated by the restrained afterburning in the freeboard, the increased coke burning efficiency, the lower coke content in the regenerated catalysts. Comparatively, adding a properly design horizontal baffle was proved to be more effective and should be a primary intensification measure used in industrial regenerators. A better spent catalyst distributor was suggested to be used to help the inserted horizontal baffles further improve the performance of the regenerator. By the simulation, more flow-reaction coupling mechanisms during the regeneration process are capable to be understood in more depth. The effectiveness of different intensification measures depends both on the resulted matching quality between the distributions of spent catalyst and oxygen in the main air, and the solids residence time distribution.