Gas Hold Up and Mixing in the Liquid Phase of Bubble Columns Used in Continuous Fermentation

Abstract

The bubble column has recently received a great deal of attention
since its applications are increasing. Recent work has shown that there
is a viable possibility of utilising bubble columns in aerobic systems
such as fermentation.

At present there is a considerable amount of knowledge available on
the various parameters affecting the operation of systems. Unfortunately
the majority of the research work carried out has been with simple two phase
systems such as air/water. Consequently there is virtually no
working design-data for complex two-phase and three-phase systems.

The object of this research programme was to attempt to apply
present two-phase knowledge to three-phase systems and to endeavour to
determine the effects of various parameters, if they act differently.

The initial experimental work was concerned with obtaining a reliable
and reproducible means of determining bubble diameters and a preliminary
study of the factors affecting the size of bubbles generated from single
orifices in yeast suspensions. The work then progressed to some small-scale
studies of two-phase systems in an effort to relate the initial
single bubble data to bubble swarm systems.

The physical size of the apparatus was then increased to simulate
industrial type equipment. Extensive studies were carried out with this
equipment to measure the effects of gas and liquid flow-rates and column
diameter on gas hold-up in yeast suspensions of varying concentrations,
in comparison to air/water systems, Finally, a study of the liquid-phase
mixing was made, using the same parameters.

The overall object of this thesis is to put forward preliminary
data on two and three-phase systems which, it is hoped, will enable more
extensive studies to be carried out on various aspects of the work.

Date of Award	1972
Original language	English