title: The influence of vessel height and top-section size on the hydrodynamic characteristics of airlift fermentors.
abstract: Fermentations of the yeast Saccharomyces cerevisiae were carried out in a 90 to 250-L working volume concentric tube airlift fermentor. Measurements of liquid circulation velocity, gas hold-up, and liquid mixing were made under varying conditions of gas flowrate, vessel height, and top-section size. Both liquid circulation velocity and mixing time increased with vessel height. Liquid velocity varied approximately in proportion to the square root of column height, supporting a theoretically based relationship. The effect of vessel height on gas hold-up was negligible. The height of the top-section had a significant effect on liquid mixing. Mixing time decreased with increasing size of the top-section up to a critical height. As the top-section was expanded beyond this height, little improvement in mixing was seen. This indicated the presence of a two-zone flow pattern in the top-section. Liquid velocity and gas hold-up were essentially independent of top-section height. (c) 1994 John Wiley & Sons, Inc.
authors.affiliation: The Advanced Centre for Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom.
authors.forename: A B
authors.initials: AB
authors.lastname: Russell
authors.forename: C R
authors.initials: CR
authors.lastname: Thomas
authors.forename: M D
authors.initials: MD
authors.lastname: Lilly