A Hybrid Technique for Coupling Chemical Kinetics and Hydrodynamics Computations in Multi-Phase Reacting Flow Systems

A hybrid technique to couple hydrodynamics and chemical kinetics calculations in a multi-phase, multi-species, turbulent reacting flow simulation has been developed. It divides a flow simulation into two parts: a reacting flow hydrodynamic simulation with a small but sufficient number of lumped reactions to compute flow field properties followed by a many subspecies (of order 10 to 100) reaction kinetics and transport calculation. This technique has been incorporated in a computational fluid dynamics (CFD) code to predict concentrations of many subspecies in a reacting flow where complex chemical reactions take place, and it can be applied to many applications such as combustors. The application presented in this paper is the flow simulation of a fluid catalytic cracking (FCC) riser reactor. Applying the technique in the FCC riser application has shown that it can be used to identify critical processes and operating parameters including the trends and relationships that are necessary to the improve the quality and quantity of FCC products.