The specific interfacial area in external-circulation-loop airlifts and a bubble column-I. Aqueous sodium sulphite solution

• Published in: Chemical engineering science Vol. 42; no. 12; pp. 2811 - 2824
• Main Authors: Popović, Milan, Robinson, Campbell W.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1987; Elsevier
• Subjects: Biological and medical sciences; Biotechnology; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Design; Gas liquid interface; Hydrodynamic properties; Gas holdup; Sulfites; Bioreactor; Bubble column; Air lift; Measurement method; Comparative study; Interfacial area
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/0009-2509(87)87048-3

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 a 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 = 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 by the chemical and photographic methods were also measured and are reported. While the data for a obtained by the chemical and light scattering methods agree well, a significant discrepancy was found with the results obtained using the photographic method. The specific interfacial area is shown to be mainly dependent on the downcomer-to-riser cross-sectional area ratio and the superficial gas velocity. However, the effects of liquid velocity, dispersion height and sparger hole diameter have also been taken into account to facilitate comparison with other works.