Computational modeling of gas/particle flow in a riser

Axial solid velocity, solid volume fraction, and solid shear viscosity were computed in the riser of a circulating fluidized-bed reactor using a two-phase 2-D computational fluid dynamic model. The time-averaged model predictions agree well with the experimental data of Miller and Gidaspow (1992). The model predicts a core-annulus flow in the riser, similar to that found experimentally. The maximum velocity in the core agrees well with the measurements, but the downflow in the annulus is somewhat overpredicted. The solid volume fractions profiles agree well in both core and annulus, with discrepancy in the core at the level close to the inlet. The radial profile of solid shear viscosity computed by the turbulent kinetic energy model is ten times lower in the core than that found experimentally but with a linear function of solid volume fraction in the measurement, the computed profile agrees well with experiments.