THE SPECIFIC INTERFACIAL AREA IN EXTERNAL-CIRCULATION-LOOP AIRLIFTS AND A BUBBLE COLUMN .1. AQUEOUS SODIUM-SULFITE SOLUTION

In order to contribute to general knowledge of the performance and design of external-circulation-loop type airlift fermentors, the specific gas-liquid interfacial area alpha was studied. Three different measurement methods were applied, namely sulphite oxidation, light scattering and photographic. Two sizes of fermentors having downcomer-to-riser cross-sectional area ratios (A//d/A//r) of 0. 111 and 0. 444 were employed. Parallel studies in a bubble-column-type fermentor (A//d/A//r equals 0) were carried out for comparison. Experimental data on the liquid circulation velocity, gas hold-ups in the riser and the downcomer and the average bubble diameter necessary for evaluation of a alpha by the chemical and photographic methods were also measured and are reported.