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 de lta paddle impellers (10 cm and 20 cm diameter) in water in a 30 cm sq uare sectioned baffled tank. Power consumption under ungassed conditio ns was measured in viscous mineral oil. For the 20 cm impeller, the ef fects of minor design modifications, such as sweeping the blade forwar d or back, have also been examined. The power numbers are approximatel y 2. 0 in the absence of sparged gas, but are reduced by over 50 % whe n gas is supplied beneath the impeller. Mass transfer data can be corr elated with the power input per unit volume and the superficial gas ve locity, showing that the performance with aeration of water is compara ble to that reported by previous workers for the Rushton turbine impel ler.