Pulsing to improve bubble column performance: II. Jetting gas rates

Knopf, F. Carl; Waghmare, Yogesh; Ma, Jia; Rice, Richard G.

doi:10.1002/aic.10699

Cited by 22 publications

(42 citation statements)

References 18 publications

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“…Particular frequencies and vibration modes correspond to significant intensification of mass transfer and void fraction [12][13][14][15][16][17][18][19][20][21][22]. The current mass transfer measurements were validated with comparison to a subset of conditions tested in Waghmare et al [19].…”

Section: Volumetric Mass Transfer Coefficientmentioning

confidence: 88%

“…Due to scarcity of models for prediction of mass transfer in vibrating bubble columns, we decided to provide a correlation to predict mass transfer and test it within the range of our experimental data as well as that of Waghmare et al [18]. Previous works [10,[16][17][18][19] have contributed a physics-based model that supports the theory that specific power P m and superficial gas velocity U SG are the primary factors in mass transfer. However, Waghmare et al [18,19] have been supported in part by limited experimental evidence.…”

Section: Volumetric Mass Transfer Coefficientmentioning

confidence: 91%

“…More recently, there has been a renewed interest in the study of vibrating bubble columns [12][13][14][15][16][17][18][19][20][21][22]. These recent efforts have developed theoretical physics-based models to predict mass transfer and void fraction in bubble column reactor (BCR) systems undergoing vibration [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…is a common way to determine the volumetric mass transfer coefficient (k L a) within a BCR [13,17,18,[21][22][23]. Here, C is the instantaneous concentration of dissolved gas in the liquid, C* is the saturation concentration, t is time, k L is the liquid mass transfer coefficient, and a is the phase interfacial area.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, while most previous studies have primarily focused on frequency dependence, some have examined the influence of amplitude and found that at low power input significant improvement in column efficiency is possible with increasing amplitude [14,17]. Thus, the current work employs a multi-scale approach [29], to investigate the effect of amplitude on mass transfer with measurements of volumetric mass transfer coefficient k L a, void fraction ε (column-scale) and Sauter mean diameter d 32 (bubble-scale).…”

Section: Introductionmentioning

confidence: 99%

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Study of Bubble Size, Void Fraction, and Mass Transport in a Bubble Column under High Amplitude Vibration

et al. 2018

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Abstract:Vertical vibration is known to cause bubble breakup, clustering and retardation in gas-liquid systems. In a bubble column, vibration increases the mass transfer ratio by increasing the residence time and phase interfacial area through introducing kinetic buoyancy force (Bjerknes effect) and bubble breakup. Previous studies have explored the effect of vibration frequency (f ), but minimal effort has focused on the effect of amplitude (A) on mass transfer intensification. Thus, the current work experimentally examines bubble size, void fraction, and mass transfer in a bubble column under relatively high amplitude vibration (1.5 mm < A <9.5 mm) over a frequency range of 7.5-22.5 Hz.Results of the present work were compared with past studies. The maximum stable bubble size under vibration was scaled using Hinze theory for breakage. Results of this work indicate that vibration frequency exhibits local maxima in both mass transfer and void fraction. Moreover, an optimum amplitude that is independent of vibration frequency was found for mass transfer enhancements. Finally, this work suggests physics-based models to predict void fraction and mass transfer in a vibrating bubble column.

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Section: Volumetric Mass Transfer Coefficientmentioning

confidence: 88%

Section: Volumetric Mass Transfer Coefficientmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study of Bubble Size, Void Fraction, and Mass Transport in a Bubble Column under High Amplitude Vibration

et al. 2018

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The Bjerknes effect: Explaining pulsed‐flow behavior in bubble columns

2007

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New experimental data for a range of gas velocities from 0.1 to 1.5 cm/s are explained by an elementary theory that combines the effect of bubble retardation owing to Bjerknes forces with the breakage relationship of Hinze in a pulsed‐bubble column. A frequency range from 10 to 30 Hz, and two amplitudes of fluid oscillation were used in the 8.9 cm column: 1.66 and 2.46 mm. Experimental values of volumetric mass‐transfer coefficient for oxygen dissolution followed predictions of theory using a modified penetration model. A new phenomenon was observed and was predictable from theory, namely “flooding”, which arises when bubbles are partially or fully retarded by Bjerknes forces at the point of injection. Under flooding conditions, transport enhancement levels off as frequency or amplitude is increased. Bubble‐size distribution was measured as a function of frequency, and the calculated Sauter‐mean diameter was satisfactorily fitted by the Hinze breakage formula. © 2007 American Institute of Chemical Engineers AIChE J, 2007

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Polymer hydrogenation in pulsed flow systems with extrusion

Bussard

Dooley

2008

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).The hydrogenation of poly(styrene) over a Pd/Al 2 O 3 catalyst was studied in reactors where pulsed flows are present due to both extrusion and forced pulsing. The reaction was investigated over a range of flow rates, polymer concentrations, and pulsing conditions. Observed activities were highly related to gas-to-liquid mass transfer rates predicted by a correlation for slug flow in catalyst monoliths. A reactor fed by a liquid-starved extruder is an attractive choice for hydrogenation at low polymer concentrations, where intrinsic reaction rates are approached. Higher polymer concentrations (10 wt %) lead to higher mass transfer resistances and a decrease in observed activity. But in this case forced pulsing has a greater effect on productivity; an optimum pulsing frequency was observed. Selectivity was higher and power input lower than in a stirred tank at comparable conditions. The optimal frequency is higher than those found in previous work on hydrogenations.

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Pulsing to improve bubble column performance: II. Jetting gas rates

Cited by 22 publications

References 18 publications

Study of Bubble Size, Void Fraction, and Mass Transport in a Bubble Column under High Amplitude Vibration

Study of Bubble Size, Void Fraction, and Mass Transport in a Bubble Column under High Amplitude Vibration

The Bjerknes effect: Explaining pulsed‐flow behavior in bubble columns

Polymer hydrogenation in pulsed flow systems with extrusion

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