Effects of sparger height and orifice orientation on solids dispersion in a slurry bubble column

Abstract

The effects of gas distributor height and the orientation of its orifices are investigated on solids dispersion and gas holdup profiles in a three-phase slurry bubble column. The height of the distributor was varied to cover locations from near column bottom to above the settled solids bed height. The orifice orientations were changed from upward facing to downwards facing directions. The measurements were conducted in a Plexiglas column of 0.15 m ID and 2.5 m height. The gas phase was oil-free compressed air while tap water was used as liquid phase. Glass beads with an average particle diameter of 35 μm and density of 2450 kg/m3 constituted the solid phase. The settled bed height was about 0.4 m which provided an average slurry concentration of about 15% (v/v) when all solids were dispersed. Both axial and column average phase holdups were measured. Effects of sparger location, gas jets formation and liquid circulation patterns on gas holdups and solids dispersion are analyzed. Empirical correlations are developed to relate sparger location to solids dispersion as a function of gas velocity. Optimum sparger height and orifice orientation is proposed based on the measurement of this study.