Volumetric gas-phase mass transfer coefficients based on the vessel volume,
kGa'', were determined in baffled horizontal stirred vessels of four different diameters D
t from 0.159 to 0.493 m, equipped with turbine impellers, by absorption experiments on NH
3-H
2SO
4 and H
2S-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/D
t)/
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.
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