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Electrolyte effects on recirculating dense bubbly flow: An experimental study using X‐ray imaging
Author(s) -
Mandalahalli Manas M.,
Wagner Evert C.,
Portela Luis M.,
Mudde Robert F.
Publication year - 2020
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16696
Subject(s) - bubble , sparging , electrolyte , coalescence (physics) , mechanics , porosity , agglomerate , chemistry , materials science , slurry , volumetric flow rate , analytical chemistry (journal) , chromatography , electrode , composite material , physics , astrobiology
Abstract In this work, the effect of an electrolyte (up to 2 M of NaCl dissolved in water) on a homogeneous dense bubbly flow, in an airlift bubble column, is studied using nonintrusive techniques. X‐ray and high‐speed imaging are used to investigate the bubble size distribution, the local and the global gas‐fraction profiles. The major effect of the electrolyte is the bubble size distribution at the fine‐pore sparger, which is a consequence of the bubble coalescence inhibition promoted by the electrolyte. The bubble plume widening, the increase in overall gas fraction, and the onset of bubble recirculation in the column can all be explained by the bubble size reduction at the fine‐pore spargers. As a result of the bubble size reduction, the overall role of the electrolyte is in a reduction of the driving force for the liquid recirculation. Furthermore, an accumulation of the small bubbles causes a layer of foam at the free surface, which is dynamic in nature and induces additional bubble recirculation.