AN AVERAGE GAS HOLD-UP AND LIQUID CIRCULATION VELOCITY IN AIRLIFT REACTORS WITH EXTERNAL LOOP

Experimental investigations were carried out in model airlift reactors with external loops. Two reactors of laboratory scale (height 1.95 m, internal diameter 0.1 m, volume 0.08 m3) and pilot-plant scale (height 7.18 m, internal diameter 0.2 m, volume 0.7 m3) were used. The influence of reactor geometry, gas sparger design, liquid properties (both Newtonian and non-Newtonian) and the amount of introduced air was investigated. The influence of gas sparger design on ps hold-up and liquid velocity was found to be negligible. A modified method for the prediction of liquid circulation velocity-based on the energy balance of the reactor-was proposed. An original dimensionless correlation for gas hold-up prediction involving superficial velocities of gas and liquid, cross-sectional areas, as well as Froude and Morton numbers, was obtained.