OXYGEN ABSORPTION IN A BAFFLED TANK AGITATED BY DELTA PADDLE IMPELLER

The power consumption and the volume-based mass transfer coefficient (k(l)a) for oxygen uptake from air into water have been measured for delta paddle impellers (10 cm and 20 cm diameter) in water in a 30 cm square sectioned baffled tank. Power consumption under ungassed conditions was measured in viscous mineral oil. For the 20 cm impeller, the effects of minor design modifications, such as sweeping the blade forward or back, have also been examined. The power numbers are approximately 2. 0 in the absence of sparged gas, but are reduced by over 50 % when gas is supplied beneath the impeller. Mass transfer data can be correlated with the power input per unit volume and the superficial gas velocity, showing that the performance with aeration of water is comparable to that reported by previous workers for the Rushton turbine impeller.