Gas Holdup and Volumetric Mass Transfer Coefficient in a Slurry Bubble Column

The gas holdup, ϵ, and volumetric mass transfer coefficient, k L a , were measured in a 0.051 m diameter glass column with ethanol as the liquid phase and cobalt catalyst as the solid phase in concentrations of 1.0 and 3.8 vol.‐%. The superficial gas velocity U was varied in the range from 0 to 0.11 m/s, spanning both the homogeneous and heterogeneous flow regimes. Experimental results show that increasing catalyst concentration decreases the gas holdup to a significant extent. The volumetric mass transfer coefficient, k L a , closely follows the trend in gas holdup. Above a superficial gas velocity of 0.04 m/s the value of k L a /ϵ was found to be practically independent of slurry concentration and the gas velocity U ; the value of this parameter is found to be about 0.45 s –1 . Our studies provide a simple method for the estimation of k L a in industrial‐size bubble column slurry reactors.