Modeling and optimization of a model IV fluidized catalytic cracking unit

Abstract

Abstract The problem of on‐line optimization of a model IV fluidized catalytic cracking (FCC) unit is analyzed. The “process” was modeled by combining a model IV FCC unit dynamic simulator (McFarlane et al, 1993; Khandalekar, 1993) with a ten‐lump yield model (Jacob et al, 1976; Arbel et al., 1995) for the reactor section. The steady‐state optimization model consisted of macroscopic steady‐state models of the regenerator and reactor, a simplified reactor yield model, and models of the various process constraints. The steady‐state optimization problem was solved using successive quadratic programming software (NPSOL, Gill et al., 1986) and the optimum process set points were implemented on the process simulator using a nonlinear constraint controller (Kandalekar and Riggs, 1995). The relative performance of constraint control, off‐line optimization, and on‐line optimization is compared for different feed characteristics and product pricing structures.