MODELING, SIMULATION AND OPTIMIZATION OF FCC DOWNER REACTOR

Abstract

FCC process plays an important role in heavy oil cracking. Recently, FCC process becomes very important due to increase in demand of petrochemical products. Therefore, relatively novel FCC process configuration where a downer reactor has been proposed in place of conventional riser reactor. Downer reactor has unique features where gas and solids move downward co-currently and it accommodates high-severity operation at the initial stage. The operation principles of downer reactor are close to plug flow reactor. It has been reported that the downer reactor have major advantages over the conventional riser. Downer reactor usually reduces the contact time during thermal cracking and eliminates back mixing which produce undesired product such as dry gas and coke. Here in this study, mathematical model for downer reactor and regenerator have been developed. To model the cracking reaction of gas oil to lighter fractions and coke five-lump model was used. Nine kinetic parameters and one catalyst deactivation activity were considered. To generate the steady-state model of the integrated reactor gross assumption were made for the hydrodynamics parameter. Runga Kutta method were used to solve the differential equations obtained, by MTLABTm 7. The obtained parameter of FCCU downer reactor such as profitability and satisfy real-life constraints were optimized using Non dominated sorting genetic algorithm (NSGA-II). Two objective function optimization problems were solved using NSGA —II to find out maximum gasoline yield and minimum catalyst flow rate.