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Measurement of k L a by dynamic pressure method in pilot‐plant fermentor
Author(s) -
Linek V.,
Moucha T.,
Doušová M.,
Sinkule J.
Publication year - 1994
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.260430607
Subject(s) - bandwidth throttling , chemistry , distilled water , analytical chemistry (journal) , thermodynamics , aqueous solution , fermentation , oxygen , dynamic pressure , absorption (acoustics) , aeration , mechanics , chromatography , materials science , physics , food science , organic chemistry , gas compressor , composite material
The dynamic pressure method (DPM) is used for measurement of k L a in a 1‐m 3 pilot scale fermentor in coalescing (distilled water) and noncoalescing (0.3 M Na 2 SO 4 aqueous solution) batches. The method consists in recording oxygen concentration in a batch after a small pressure change (20 kPa) in the fermentor. The upward pressure change is brought about by temporary closing and subsequent throttling of outlet gas stream and the downward change by full reopening of the gas outlet. Absorption of pure oxygen yields the same k L a values as absorption of air. In noncoalescing batch, the downward k L a values are always higher than the upward values owing to spontaneous nucleation of bubbles. The experiments performed in a stirred cell confirm this behavior. Thus, only upward pressure change should be used for measurement. The correlation of k L a data measured in small (18‐L) and large (1000‐L) vessels based on power dissipated and superficial gas velocity are in a good agreement. Unlike the DPM, the classical dynamic methods yield, under the same conditions, excessively low values of k L a (the dynamic startup method) or fail to produce data at all (the dynamic method with interchange of air for N 2 ). © 1994 John Wiley & Sons, Inc.