(27g) Mass Transfer In A Viscous Bubble Column With Pulsed-Flow: The Bjerknes Effect

Previously(1,2,3) it has been shown that low amplitude (0.5 mm? 2.5 mm) oscillations at moderate frequencies ( 0 ? 25 Hz) can be used to improve the bubble column performance. Available literature on oscillating bubble columns mainly focuses on air-water system (Viscosity ~ 1 cP). In present work, effect of oscillations on the mass transfer coefficient in the oscillating bubble column was studied for various CMC solutions in the viscosity range 1 - 50 cP. Similar to previously reported results for air-water system, viscous systems exhibit initial increase in mass transfer coefficient as a function of frequency and then reach a plateau. This plateau behavior can be attributed to Bjerknes forces acting on a bubble. The shape of the curve for mass transfer coefficient vs frequency remains unchanged for viscous systems, but the absolute value of the mass transfer coefficient decreases as a function of increasing viscosity.

1.Knopf FC, Ma J, Rice RG, Nikitopoulos D. Pulsing to improve bubble column performance: I Low gas rates. AIChE J. 2006;52:1103-1115. 2.Knopf FC, Waghmare Y, Ma J, Rice RG. Pulsing to improve bubble column performance: II Jetting gas rates. AIChE J. 2006;52:1116-1126. 3.Waghmare YG, Knopf FC, Rice RG. A new theory to explain transport in pulsed-flow bubble columns: the Bjerknes effect. AIChE J. 2007; accepted for publication.