ADVANCED MODELING OF FLUID CATALYTIC CRACKING RISER-TYPE REACTORS

A mathematical model is developed that predicts three-dimensional, two-phase-flow, heat transfer and reaction inside catalytic cracking riser-type reactors. The model consists of the full set of partial-differential equations that describe the conservation of mass, momentum, energy and chemical species for both phases in the reactor, coupled with empirical correlations concerning interphase friction, interphase heat-transfer and fluid-to-wall frictional forces. The cracking reaction is simulated by a simple three-lump kinetic model, but more realistic kinetic models can be easily included. The model can predict the most important engineering aspects of a riser reactor including pressure drop, catalyst holdup, interphase slip velocity, catalyst acceleration zone, choking behavior and temperature distribution in both phases, and yields distribution all over the reactor. It can also predict other complex engineering three-dimensional, two-phase problems realistically using computational fluid dynamics techniques.