Numerical Simulation of an Industrial Fluid Catalytic Cracking Regenerator

Fluid catalytic cracking (FCC) is one of the most important conversion processes in petroleum refineries, and FCC regenerator is a key part of an FCC unit to recover the solid catalyst activity by burning off the deposited coke on the catalyst surface. In modern FCC units, regenerator is a cylindrical vessel. Carrier gas transports the solid catalyst from the stripper and feeds the catalyst into the regenerator through catalyst distributors. The catalyst is fluidized by the air that is injected into the regenerator through air rings in the bottom part of the cylindrical vessel. A three-dimensional multi-phase, multi-species reacting flow computational fluid dynamics (CFD) model was established to simulate the flow inside an FCC regenerator. The two phases involved in the flow are gas phase and solid phase. The Euler-Euler approach, where the two phases are considered to be continuous and fully inter-penetrating, is employed. The model includes gas-solid momentum exchange, gas-solid heat exchange, gas-solid mass exchange, and chemical reactions. Chemical reactions incorporated into the model simulate the combustion of coke which is present on the catalyst surface. The simulation results show a good agreement with plant data.