Spectral analysis for hydrodynamic and gas-liquid mass transfer in a
bubble column: Effect of non – coalescing system.
Spectral analysis and statistical studies were investigated in a semi
pilot bubble column using wall pressure sensors in different axial
position both in the air–water system and in water–alcohol solutions
(ethanol, 2-propanol and 1-butanol). Gas holdup is more important in the
zone far enough to the gas distributor. Then volumetric mass transfer
coefficient (KLa) was measured for three axial positions. Interesting
results show clearly by the average frequency, that regime transition is
delayed for the coalescence inhibitor system and more particularly with
the increase in the carbon number of the alcohol. Cross correlation and
coherence between two pressure sensors signals revealed clearly that the
transition of the flow regime starts when the periodicity appears for a
certain gas velocity. The results of the gas liquid mass transfer
revealed that KLa decreased with addition of alcohol which is explained
by Higbie’s theory.