Kinetic theory based CFD simulation of turbulent fluidization of FCC particles in a riser

Abstract

The turbulent fluidization regime is characterized by the co-existence of a dense, bottom region and a dilute, top bed. A kinetic theory based CFD code with a drag corrected for clusters captured the basic features of this flow regime: the dilute and dense regions, high dispersion coefficients and a strong anisotropy. The computed energy spectrum captures the observed gravity wave and the Kolmogorov - 5 / 3 law at high frequencies. The computed turbulent kinetic energy is close to the measurements for FCC particles. The CFD simulations compared reasonably well with the measured core-annular flow experiments at very high solid fluxes. The computed granular temperatures, solids pressures, FCC viscosities and frequencies of oscillations were close to measurements reported in the literature. The computations suggest that unlike for the flow of group B particles, the oscillations for the FCC particles in the center of the riser are primarily due to the oscillations of clusters and not due to oscillations of individual particles. Hence mixing is not on the level of individual particles.