Chemical Engineering Research & Design, Vol.115, 44-52, 2016
Packing effect on mass transfer and hydrodynamics of rising toluene drops in stagnant liquid
Terminal velocity and mass transfer of rising drops in a stagnant liquid were experimentally measured. The chemical system included the toluene drops whose acetic acid content was transferred to the surrounding water. Three sets of structured packing were used in the column to investigate the impact of packing at different heights of 10, 25 and 40 cm. The effects of flow rate (Q), drop size (d), inverse viscosity (N-f), Eotvos number (Eo), and Reynolds number (Re) on terminal velocity, u(t), and Froude number, Fr, were investigated. The critical points of d = 3.4 mm, Eo = 0.5 and N-f=200 were found at which two regions of circulating and oscillating drops were separated, and the Fr was constant within each region. The effect of packing height on Fr and Sherwood number against Reynolds number was also investigated. Compared to the non-packed column it was revealed that a 30% increase in Sherwood number could be achieved using a packing with 40 cm in height. Moreover, it was found that simultaneous increase of packing height and the flow rate consistently enhanced the mass transfer coefficient. Finally, a correlation was proposed which permitted the prediction of Sherwood number versus the dimensionless numbers of Reynolds, Weber and the packing height ratio. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.