The axial mixing and mass-transfer characteristics of a Karr column when used as a cocurrent, gas-liquid contactor were experimentally determined. The liquid-phase backmixlng is extremely small, and the plug flow can be safely assumed in this column over the ranges 0.6 cm/s < VL < 4.34 cm/s, 0.7 cm/s < Vg < 5 cm/s, and 1.8 cm/s < AF < 7.5 cm/s. Over the same ranges, the liquid-side volumetric mass-transfer coefficient kLa was found to increase significantly with an increasing liquid velocity, gas velocity, or speed of plate reciprocation. The effect of the liquid flow rate is particularly strong because of its simultaneous, favorable influence on the liquid-side coefficient kL and the interfacial area a. Both the speed of plate reciprocation and the gas flow rate were found to have a highly adverse effect on kL. Satisfactory correlations of kLa and of kL based on the liquid velocity at the orifices of the plates are presented.

Radial and axial dispersion of liquid in a single-phase flow through a column packed with open-end screen cylinders were measured as a function of liquid flow rate and packing characteristics using a point injection technique and a transient response technique, respectively. Results show that radial dispersion coefficient increases linearly with liquid flow rate. It also increases with increasing wire diameter and mesh number, but decreases with increasing packing dimension over the range of variables studied. A correlation is presented for radial dispersion coefficients as a function of the Reynolds number, up/dmg and the ratio, dw/dn• The experimentally obtained residence-time distribution curves were interpreted by means of a one-dimensional dispersion model. The axial dispersion coefficient was found to increase with increasing liquid flow rate and packing dimension, but it was insensitive to the change of packing mesh number from 8 to 14 meshes/in. 11 has been reported recently that on addition of openend screen cylinders to a gas-solid fluidized column (Chen and Osberg, 1967a;Ishii and Osberg, 1965;Sutherland et al., 1963) or to a gas-liquid bubble column (Chen and

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