Modelling catalyst regeneration in an industrial FCC unit

Predictive models for process parameters during regeneration of spent catalyst in an industrial fluid catalytic cracking (FCC) unit are presented. The models adopt a twophase theory where the dense region of the regenerator is divided into a bubble-phase and an emulsion-phase. The bubble-phase is modelled as a plug flow reactor, while the emulsion-phase is modelled as a continuous stirred tank reactor (CSTR). Profiles for regenerator-temperature, quantity of coke burnt, and flue gas composition, at different operating conditions are also presented. Model-predictions are compared with plant data and good agreement is obtained. Simulation results indicate that inlet-air velocity and catalyst-bed height have significant influence on the performance of the rege nerator. The model-estimated optimum operating conditions of the regenerator are regeneratortemperature of about 1000 K, inlet-air velocity of about 13.5 m/s, and catalyst-bed height of 13 m.