Multiphase Phenomena in a Vibrating Column Reactor
Abstract
Bubble column reactors (BCRs) are used in chemical, petroleum, and bio-systems processing applications like the hydrogenation of coal slurry to produce synthetic fuels in the Fischer-Tropsch process. Vibration of a BCR has been shown to increase mass transfer rates, and an interesting multiphase phenomenon called kinetic buoyancy or "Bjerknes force" has been observed. However, the effect of kinetic buoyancy on the flow field and mass transfer is not fully understood. While previous research has focused on the effect of vibration frequency (10 < f < 120 Hz) at low amplitudes, (A < 2.5 mm) very little has been performed at larger amplitudes. Therefore, a new experimental set up was designed and built which includes a shaking device capable of vertically oscillating an 18 kg (40 lbm) test column at frequencies of 0-40 Hz and amplitudes of 1&ndash10 mm. The experimental set up was verified by comparison to previous research, and used to collect mass transfer, void fraction and bubble size data at high amplitude (A = 2.5-9.5 mm) over a frequency range of 7.5-22.5 Hz. Comparison of the results with previous research shows similar local maxima occur for void fraction and mass transfer, and also indicates an optimum amplitude may exist for mass transfer, independent of frequency. Analysis and comparison of this research and available data from the literature suggests a stronger correlation between kinetic buoyancy and mass transfer than previously theorized.
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- OSU Theses [15752]