Radial hydrodynamics in risers

On the basis of the benchmark modeling exercise at Fluidization VIII, predi cting riser hydrodynamics continues to be more of an art than a science. Te n different hydrodynamic models were compared with a set of experimental da ta that covered a wide range of operating conditions and showed reasonable to poor overall agreement. Herein, we describe the model that gave the best overall agreement with: the experimental data. Density is calculated by a correlation based on slip factor, and the radial voidage profile depends so lely on the cross-sectional average void fraction. Both the gas and velocit y profile follows a power law type expression; the gas velocity at the wall is zero. The model predictions agree well with experiments conducted with sand but not as well as those conducted with fluidized catalytic cracking c atalyst.