Abstract
Conceptual multi-stage fluid catalytic cracking (FCC) units that use several short risers are considered by some refining industries to enhance product yields and product selectivity. A validated computational fluid dynamic (CFD) code was used to evaluate the concept. The code solves conservation equations of FCC flow properties for three phases: gaseous species, oil droplets, and catalyst particles. Phenomenological models were developed to characterize multi-phase interactions, including interfacial drag and heat transfer, droplet vaporization, cracking reactions, and flow turbulence. Parametric and optimization studies were performed to evaluate the impacts of operation/design parameters on the product yields of the conceptual advanced FCC units. The results showed that promising product yields and selectively could be achieved by proper design of stage arrangements and operation parameters.
