Novel Integrated Reactor-Regenerator Model for the Fluidized Catalytic Cracking Unit Based on an Equivalent Reactor Network

Fluidized catalytic cracking (FCC) is the most used process for converting heavy oil into more valuable fuels and chemical products such as gasoline and propylene. The conventional steady state and dynamic models that have commonly been used to study FCC units assume simple plug flow in the riser reactor and two-region (i.e., freeboard and dense bed) - two-phase (i.e., bubble phase and emulsion phase) in the catalyst regenerator. As a remedy to the limited accuracy yielded by such assumptions, an integrated model based on the equivalent reactor network (ERN) approach is built in order to accurately model a pilot-scale residue FCC (RFCC) unit. The model involves 8-reactor and 10-reactor networks to characterize complex hydrodynamics within the regenerator and the riser reactor, respectively. Also, a coke combustion kinetic model and a ten-lump kinetic model describing the cracking reactions, as well as the necessary thermodynamic models, are coupled with the ERN hydrodynamic models. The validation of the integrated models shows good agreement with available experimental data. The model is subsequently used to investigate the effects of operating conditions such as reaction temperature, residence time, and catalyst-to-oil ratio on the product yield distribution in the RFCC unit. Finally, the model is used to demonstrate the superiority of the RFCC-Maxing-Propylene process over the conventional RFCC process. It is believed that the developed model can help researchers and engineers carry out further RFCC process investigations such as dynamic analysis and real-time control and optimization.