A comprehensive experimental study of the hydrodynamic behaviors for the specific system of air/paraffin oil/silica particles in a slurry bubble column of 0.15 m diameter and 2.9 m length has been carried out. The effect of regime transition, solid concentrations, static liquid height, sparger type and related bubble size on gas holdup over a range of superficial gas velocities has been investigated. From the experimental work, it is revealed that the gas holdup increases by increasing the superficial gas velocity and transition regime occurred at 0.043 to 0.08 m/s. The slope of this curve is steeper for homogeneous regime and less for heterogeneous regime. In addition, the presence of silica particle (0–40 vol %) inhibits bubble breakage, increases rise velocity and consequently decreases residence time and gas holdup. Approximately a 40% decrease in the overall gas holdup was observed by adding 40% solid particles to the air/paraffin oil system. Moreover, increasing static liquid height from 6 to 12 leads to about a 61% decrease in gas holdup in the absence of solid particles. Also, the use of a perforated plate instead of a porous one causes a 9% increase and a 21% decrease in bubble size and gas holdup, respectively. Finally, it is found that the Krishna and Sie correlation can predict gas holdup in the air/paraffin oil/silica particles system with an acceptable minimum relative error of about 8%.

Keywords