MECHANICAL CONTROL OF FOAMING IN TOWER REACTORS

Rotating-disk mechanical foam-breakers (MFRDs) were applied to the con trol of foaming in bubble column (BC) reactors containing complex solu tions and biological media. The foaming behaviour of BCs and the foam- breaking behaviour of MFRDs fitted to BCs were evaluated respectively from the changes in the liquid hold-up in ascending foam, phi(b), and the required critical disk rotational speed, N(c), for foam-breaking. The differences in phi(b) and N(c), reflecting the difficulty or ease of foam-breaking among the liquids, correlated well with differences i n the foaming characteristic term, F(CT), of respective liquids, which could be determined on the basis of the results measured in the exper imental small foaming apparatus which were different from those measur ed in the gas-bubbling apparatus employed in practice. The usefulness of the empirical correlations for the prediction of phi(b) and N(c), w hich can be applied independently of the type and concentration of foa ming liquid or their physical properties, was also demonstrated.