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Bubble coalescence in air-sparged bioreactors
1Department of Chemical Engineering, University of California, Berkeley, California 94720, USA.
Biotechnology and Bioengineering
|April 1, 1986
Summary
Coalescence frequency in bubble columns was measured using tracer gases. Increasing gas-sparge rates boosted frequency, while NaCl concentration decreased it, impacting bubble size.
Area of Science:
- Chemical Engineering
- Fluid Dynamics
- Multiphase Flow Systems
Background:
- Bubble columns are widely used in chemical processes for gas-liquid reactions and separations.
- Understanding bubble coalescence is crucial for optimizing mass transfer and reactor performance.
- Previous studies have explored factors affecting bubble dynamics, but comprehensive analysis of coalescence frequency under varying conditions is ongoing.
Purpose of the Study:
- To quantify the coalescence frequency in an air-sparged bubble column.
- To investigate the influence of gas-sparge rate and salt (NaCl) concentration on bubble coalescence.
- To correlate changes in coalescence frequency with bubble size distributions.
Main Methods:
- Coalescence frequency was determined by tracking the mixing rate of insoluble tracer gases within the dispersed gas phase.
- Experiments were conducted in an air-sparged bubble column.
- Bubble size distributions were measured using established techniques.
Main Results:
- Coalescence frequency increased with gas-sparge rate, correlating with gas-phase hold-up.
- NaCl concentration significantly reduced coalescence frequency, reaching approximately half that in pure water.
- Bubble size distribution showed notable changes with NaCl concentration, correlating with observed variations in coalescence frequency.
Conclusions:
- Gas-sparge rate and salt concentration are critical parameters influencing bubble coalescence in air-sparged columns.
- NaCl addition suppresses bubble coalescence, leading to altered bubble size distributions.
- The findings provide valuable insights for designing and operating bubble column reactors for enhanced efficiency.
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