Prediction of gas holdup in various types of airlift reactors

Useful correlations were derived for the prediction of available gas holdup data in air-water systems, using the operational and geometric parameters of airlift reactors only. To successfully consider the geometric difference between various types of airlift reactors, the characteristic distance (Dch) and the gas separation area (As) were defined as geometric parameters, respectively. The riser gas holdup (εr) in various types of airlift reactors was satisfactorily correlated with the operational and geometric parameters, such as the riser superficial gas velocity (UGr), a parameter containing the ratio of the top clearance to downcomer length (1+Ct/Ld), the characteristic distance to downcomer length ratio (Dch/Ld), the downcomer to riser cross-sectional area ratio (Ad/Ar), the ratio of the gas separation area to riser cross-sectional area (As/Ar), and the bottom to downcomer cross-sectional area ratio (Ab/Ad). The downcomer gas holdup in various types of airlift reactors was well correlated by a nonlinear equation involving εr, Dch/Ld, Ad/Ar, Ab/Ad, (1+Ct/Ld), and As/Ar.