Scale Effects on the Hydrodynamics of Bubble Column

S. Jameel, Farah; F. Abid, Mohammad

doi:10.30684/etj.27.10.18

	Scale Effects on the Hydrodynamics of Bubble Column
Engineering and Technology Journal
Article 1, Volume 27, Issue 10, 2009, Pages 2142-2164 PDF (566.01 K)
DOI: 10.30684/etj.27.10.18
Authors
Farah S. Jameel; Mohammad F. Abid
Abstract
The main object of this study is to investigate the influence of the column geometric and operating variables ( i.e., column diameter, superficial gas velocity and liquid viscosity) on the hydrodynamic parameter ( i.e. , gas holdup, bubble dynamics and liquid phase axial dispersion coefficient ). The experimental data obtained showed that the gas holdup increases linearly with superficial gas velocity at both homogeneous and heterogeneous regimes but the rate of increasing is slower at the heterogeneous one. The bubble rise velocity was found to decrease with increasing superficial gas velocity until a transition point was reached and after that the relationship was linearly increasing. It was observed that with an increase in liquid phase viscosity and increase in column diameters, a decrease in gas holdup and an increase in bubble size were obtained. It was observed that increasing axial position led to an increase in bubble diameter and a decrease in bubble rise velocity. Axial dispersion coefficient which is measured by tracer response technique was found to increase with gas superficial velocity, increases with column diameter, increases with axial position and decreases with liquid viscosity. This work also presents a theoretical analysis that is used to calculate the axial dispersion coefficient. The measured axial dispersion coefficient was generally consistent with the predictions of the well established correlations from the literature. The validity of the model was settled by comparing its predication with the objective function of the well-Known empirical correlation formulated by ( Hikita and Kikukawa , 1974) .The comparison shows that the present model is statistically significant at a 95% confidence level by using goodness – of – fit test . Also a statstical analysis was performed to get a general correlation for the gas holdup (εg) as a function of the parameters studied: = 0.15325 Fr 0.29617 Ga 0.09223 Bo -0.0424 g e Where the correlation coafficient ( R ) was equal to ( 0.957) and the absolute error (3.5%).
Keywords
Scale effects; Bubble column; Hydrodynamics

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