Gas hold-up in bubble columns: operation with concentrated slurries versus high viscosity liquid

Krishna, Rajamani ; Urseanu, Maria I. ; De Swart, Jeroen W. A. ; Ellenberger, Jürg (2000) Gas hold-up in bubble columns: operation with concentrated slurries versus high viscosity liquid The Canadian Journal of Chemical Engineering, 78 (3). pp. 442-448. ISSN 0008-4034

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/cjce.54...

Related URL: http://dx.doi.org/10.1002/cjce.5450780302

Abstract

The hydrodynamics of bubble columns with concentrated slurries of paraffin oil (density, ΡL = 790 kg/m3; viscosity, μL = 0.0029 Pa·s; surface tension, σ = 0.028 N·m1) containing silica particles (mean particle diameter dp = 38 μm) has been studied in columns of three different diameters, 0.1, 0.19 and 0.38 m. With increasing particle concentration, the total gas hold-up decreases significantly. This decrease is primarily caused by the destruction of the small bubble population. The hold-up of large bubbles is practically independent of the slurry concentration. The measured gas hold-up with the 36% v paraffin oil slurry shows remarkable agreement with the corresponding data obtained with Tellus oil (ρL = 862 kg/m3; μL = 0.075 Pa·s; σ = 0.028 N·m−1) as the liquid phase. Dynamic gas disengagement experiments confirm that the gas dispersion in Tellus oil also consists predominantly of large bubbles. The large bubble hold-up is found to decrease significantly with increasing column diameter. A model is developed for estimation of the large bubble gas hold-up by introduction of an wake-acceleration factor into the Davies-Taylor-Collins relation (Collins, 1967), describing the influence of the column diameter on the rise velocity of an isolated spherical cap bubble.

Item Type:Article
Source:Copyright of this article belongs to NRC Research Press.
Keywords:Bubble Columns; Large Bubbles; Small Bubbles; Churn-Turbulent Flow Regime; Concentrated Slurry; Viscous Liquid; Bubble Rise Velocity; Wall Effect; Scale Effect
ID Code:94156
Deposited On:28 Aug 2012 08:56
Last Modified:28 Aug 2012 08:56

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