FBSim: A model for fluidized bed simulation—II. Simulation of an industrial fluidized catalytic cracking regenerator

Abstract

The model for fluidized bed simulation (FBSim), developed in Part I [Faltsi-Saravelou and Vasalos, Computers chem. Engng, 15, 639 (1991)] is applied for the simulation of the regenerator of the fluid catalytic cracking (FCC) unit. Experimental data on flue gas concentrations, catalysts composition and temperature profiles in the fluidized bed have been obtained from an industrial FCC unit operating at promoted total CO burn. The predicted temperature profiles are in good agreement with industrial data and so are the predictions of gas and solid conversions. The limiting step in the regenerator operation is the non-catalytic combustion of carbon, which can be enhanced by the enrichment of the combustion air with oxygen. Simulation results show that at high temperatures the steady-state operation of the FCC regenerator is not influenced by the presence of a CO combustion promotor, although the promotor affects the temperature and component distribution between the bubble and emulsion phases. The dynamic response of the regenerator to step changes in operating variables, such as rate, composition and inlet temperature of the combustion air and coke yield is also examined.