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Flow characteristics of a pilot‐scale airlift fermentor
Author(s) -
Mercer Donald G.
Publication year - 1981
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260231104
Subject(s) - airlift , aeration , draft tube , bubble , turbulence , fermentation , mechanics , superficial velocity , chemistry , volumetric flow rate , flow (mathematics) , chromatography , materials science , bioreactor , physics , food science , organic chemistry
The effects of aeration on the flow characteristics of water in a glass pilot‐scale airlift fermentor have been examined. The 55‐L capacity fermentor consisted of a 15.2‐cm‐i.d. riser column with a 5.1‐cm‐i.d. downcomer tube. It was found that the average bubble size diminished with increased aeration. Typically, average bubble sizes ranged from 4.32 mm at a superficial gas velocity of 0.64 cm/s to 1.92 mm at 10.3 cm/s. A gas holdup of 0.19 was attained with superficial gas velocities ( v s ) on the order of 10 cm/s, indicating the highly gassed nature of the fluid in the riser section of the fermentor. Circulation velocities of markers placed in the fermentor decreased with increasing aeration rates due to increased turbulence and axial liquid back mixing within the riser section. Actual volumetric liquid circulation rates remained relatively constant (0.36–0.49 L/s) for values of ( v s ) up to 10 cm/s. Based on theoretical calculations, the ascending velocity of bubbles in a swarm reached 54 cm/s in the range of ( v s ) values studied.