Comparison, Combination and Validation of Measuring Techniques for Local Flow and Turbulence Analysis in Bubble Columns and Airlift Reactors

The applicability of velocimetry techniques based on the Doppler effect – such as laser and ultrasound Doppler velocimetry – for investigating local hydrodynamics in bubble columns and airlift reactors have been extended to non-coalescing media. Their limitations are highlighted, especially as a function of gas sparger and reactor type. The ultrasound technique was shown to be able to measure either bubble or liquid velocity. Differences in local hydrodynamics due to coalescence behaviour were used to support the analysis. Data validation was carried out both by mass balance and by comparison with other techniques, such as electrochemical probes, Pavlov tubes and optical probes.