Abstract
Volumetric gas-phase mass transfer coefficients based on the vessel volume, kGa'', were determined in baffled horizontal stirred vessels of four different diameters Dt from 0.159 to 0.493 m, equipped with turbine impellers, by absorption experiments on NH3-H2SO4 and H2S-NaOH systems, and by desorption experiments on HCN-NaCN system.
The values of kGa'' are almost independent of the liquid holdup e in the range from 0.2 to 0.7. Also, the kGa'' values are not affected significantly by the number of impellers Ni or the ratio of vessel length to diameter L/Dt under the conditions of (L/Dt)/Ni<2 and l>0.67 D)t, where l is the distance between adjacent impellers.
A dimensionless factor jD'', which is a modified jD factor, is defined and is used to correlate the data. The jD'' factor is found to be expressed in terms of dimensionless groups: the gas Reynolds number, the liquid Reynolds number based on impeller diameter and the Froude number Fr. Two relations between jD'' factor and these three dimensionless groups were obtained: one for Fr<0.2 and the other for Fr < 0.2, and the experimental results were represented by these equations with ±25% deviation.
