1987 Volume 13 Issue 5 Pages 664-670
Flow characteristics in a three-phase fluidized bed with a draft tube, 0.164 m in diameter and 2.2 m high, were experimentally examined. Air and water were used as gas and liquid. Two kinds of particles of about 3 mm φ were used : Nylon (heavier than liquid) and polypropylene (lighter than liquid). Gas was sparged either into the inner section or into the annular section.
Above a certain gas feed rate, circulation flow was stable and longitudinal distribution of solid became uniform. Gas holdup increased with increasing gas feed rate. Gas holdup for sparging into the annular section was higher than that for sparging into the inner section, excepting the case where the draft tube diameter was large and polypropylene was used as solid. In most cases solid holdup was not affected by gas feed rate.
Liquid circulation rate increased with increasing gas feed rate. The liquid circulation rate at the same gas feed rate showed the maximum in the case using the draft tube whose diameter was about 60 per-cent of column diameter. Solid and gas circulation rates depended greatly upon liquid circulation rate.
