Effect of gas sparging on the rate of mass transfer at fixed beds of horizontally stacked screens

Abstract Rates of mass transfer at air sparged fixed beds of stacked screens were measured by an electrochemical technique. Variables studied were air superficial velocity, physical properties of the solution and bed thickness. The liquid mass transfer coefficient was found to increase with air superficial velocity up to a certain point and then remain almost constant with further increase in velocity. The increase in the mass transfer coefficient as a result of air sparging ranged from 2.8 to 10 times the natural convection value depending on the operating conditions. Increasing bed thickness was found to decrease the mass transfer coefficient at a given air superficial velocity. Mass transfer data at fixed beds were correlated by the equation: j = 0.268 (Re · Fr)−0.25 (L/d)−0.35. For a single horizontal screen the data were correlated by the equation: j = 0.275 (Re · Fr)−0.21.