Premium
Evaluation of a novel self‐aerating, oscillating baffle column
Author(s) -
Mackley M. R.,
Stonestreet P.,
Thurston N. C.,
Wiseman J. S.
Publication year - 1998
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450760102
Subject(s) - baffle , aeration , mechanics , bubble , mixing (physics) , mass transfer , entrainment (biomusicology) , materials science , dispersion (optics) , body orifice , liquid bubble , flow visualization , buoyancy , volume (thermodynamics) , volumetric flow rate , orifice plate , chemistry , flow (mathematics) , thermodynamics , optics , physics , mechanical engineering , acoustics , organic chemistry , quantum mechanics , rhythm , engineering
We describe the operation of a pilot scale oscillating baffle column using a self‐aeration system for oxygenation of water. The top baffle has a high constriction ratio and is sufficiently near to the surface of the water such that gas bubbles are generated. This aeration plate is coupled with a series of equally spaced low constriction orifice baffles, which lead to uniform dispersion of entrained air bubbles throughout the liquid volume. Flow visualisation experiments using video and still photography were used to identify two mechanisms for bubble generation: bubble formation under the water surface by surface vortex suction, and bubble generation from the collapse of a surface fountain and subsequent entrainment of bubbles into the bulk. Mass transfer measurements have shown that under most conditions a uniform oxygen concentration could be obtained throughout the column as a result of efficient mixing, and that the sole limitation to mass transfer performance was determined by the aeration mechanism. Initial comparison on the basis of aeration efficiency with other devices reveals a modest oxygen transfer rate, but with low specific power consumption of order 0.3 kW/m 3 .