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 (D ch ) and the gas separation area (A s ) were defined as geometric parameters, respectively. The riser gas holdup ( ε r ) in various types of airlift reactors was satisfactorily correlated with the operational and geometric parameters, such as the riser superficial gas velocity (U Gr ), a parameter containing the ratio of the top clearance to downcomer length (1+C t /L d ), the characteristic distance to downcomer length ratio (D ch /L d ), the downcomer to riser cross-sectional area ratio (A d /A r ), the ratio of the gas separation area to riser cross-sectional area (A s /A r ), and the bottom to downcomer cross-sectional area ratio (A b /A d ). The downcomer gas holdup in various types of airlift reactors was well correlated by a nonlinear equation involving ε r , D ch /L d , A d /A r , A b /A d , (1+C t /L d ), and A s /A r .