Absorption and reaction of isobutene in sulfuric acid—III: Considerations on the scale up of bubble columns

In spite of their simple construction the scale up of bubble columns of industrial size demands application of models which account for dispersion effects and variations of pressure and gas flow rate. However, using such models and parameter values obtained from other studies it was not possible to describe successfully measured conversions of the absorption of isobutene in a 7 m bubble column though the interfacial area was determined separately. The measurements were carried out under such conditions at which the absorption takes place in the slow reaction regime of mass transfer. A sufficient agreement between experimental and predicted conversions could be obtained merely if a lower value of k_L was used. A more detailed analysis of bubble size distributions indicated that the decrease of k_L may be apparently only since the interfacial areas determined photographically must not necessarily be the area which is effective to mass transfer. k_La-values in larger bubble columns with gas spargers which are common in industry are considerably lower than k_La-data found in smaller columns with porous gas distributors.