Determination of the axial solid holdup profile by locating the splash zone in the riser

Abstract

The axial solid holdup profile in the riser was investigated to provide an upgraded entrainment model in a more prescriptive manner. The height and solid holdup of the dense zone, and the decay factor had to be determined reflecting the effect of the riser pressure drop. The dense-zone height ($z_d$) and the level of the top of the splash zone ($z_{\mathrm{spl}}$) were examined in fast fluidized beds. Correlations for $z_d$ and $z_{\mathrm{spl}}$ were proposed based on the mechanism responsible for effects of the riser pressure drop, the gas velocity in the riser, and the particle size and density. The correlations were appropriate to provide the decay factor and the solid holdup of the dense zone. Overcoming the limits of existing models, the model proposed by this study was significant with highly improved accuracy. Wall effects on $z_d$ and $z_{\mathrm{spl}}$ were remarkable.