Gas hold-up and volumetric oxygen transfer coefficient in an aerated agitated vessel without baffles having forward reverse rotating impellers

Gas hold-up and volumetric oxygen transfer coefficient were studied in a gas-liquid contactor without baffles, containing multiple impellers with four delta-type blades. The blades of each adjacent impeller were offset by 45 degrees in an alternating manner. The direction of rotation of the impellers periodically was reversed. This new type of agitated gas-liquid contactor was denoted as ''AJITER''. The effects of the gas sparging rate, the forward-reverse agitation rate and the number of impellers on the gas hold-up and volumetric oxygen transfer coefficient in the AJITER when different types of gas spargers were used were evaluated experimentally for an air-water system. Empirical relationships are presented to predict the gas hold-up and volumetric oxygen transfer coefficient. The differences in performance between the AJITER and existing types of gas-liquid contactors are discussed in terms of the differences in the gas hold-up and volumetric oxygen transfer coefficient due to changes in the superficial gas velocity.