LIQUID VELOCITY AND GAS HOLDUP IN 3-PHASE INTERNAL LOOP AIRLIFT REACTORS WITH LOW-DENSITY PARTICLES

Liquid velocity and gas holdup in three-phase internal loop airlift re actors were investigated. Air and water were used as the gas and liqui d phase, respectively, and the solid particles used were calcium algin ate beads with different particle size. The liquid velocity in the ris er and the downcomer were obtained by tracer analysis. The gas holdup in the riser and the downcomer were determined by manometric technique . It was found that the liquid velocity did not show any significant v ariations with top clearance. The liquid velocity increased with an in crease in aeration rate or draught tube length, whereas it decreased a s the diameter of the particles was increased. Moreover, the liquid ve locity and the gas holdup decreased with increasing solids loading. A hydrodynamic model based on the drift-flux model was developed to desc ribe satisfactorily the liquid velocity and gas holdup in air-water-ca lcium alginate internal loop airlift reactors.