Effect of scale on liquid recirculation in bubble columns

Abstract Successful scale-up of liquid hydrodynamics in bubble columns using a one dimensional model requires an adequate closure scheme for the Reynolds shear stress. The existing correlations for the prescription of the eddy viscosity or the mixing length scale are demonstrated to be applicable only for a limited range of conditions and consequently cannot be used for scale-up predictions. A method for estimating the mixing length scale has been explored and an attempt at unifying a wide range of data available in the literature within the purview of the method has been made. The futility of such an attempt is attributed to the nonreproducibility of the flow in different laboratories and the consequent lack of data obtained under identical conditions. It is demonstrated, however, that scale-up based on the mixing length distribution is possible when it is obtained from a consistent set of data for liquid velocity and gas void fraction profiles. Such a data set was obtained in the author's laboratory using CARPT (Computer Automated Radioactive Particle Tracking) and CT (Computed Tomography). Using the present method for prescribing the mixing length scale, model predictions for scale-up compare satisfactorily for the data that were obtained in the author's laboratory.

[1]  M. Duduković,et al.  Flow mapping in bubble columns using CARPT , 1990 .

[2]  Vivek V. Ranade,et al.  Flow in bubble columns: some numerical experiments , 1992 .

[3]  Yatish T. Shah,et al.  Design parameters estimations for bubble column reactors , 1982 .

[4]  Sailesh Kumar,et al.  A γ-ray tomographic scanner for imaging voidage distribution in two-phase flow systems , 1995 .

[5]  M. P. Duduković,et al.  Liquid backmixing in bubble columns via computer-automated radioactive particle tracking (CARPT) , 1993 .

[6]  S. D. Kim,et al.  Bubble properties and local liquid velocity in the radial direction of cocurrent gas-liquid flow , 1991 .

[7]  John L. Anderson,et al.  Bubble columns: flow transitions in the presence of trace contaminants , 1970 .

[8]  Korekazu Ueyama,et al.  Properties of recirculating turbulent two phase flow in gas bubble columns , 1979 .

[9]  H. Reichardt,et al.  Vollständige Darstellung der turbulenten Geschwindigkeitsverteilung in glatten Leitungen , 1951 .

[10]  Thomas Menzel,et al.  Reynolds shear stress for modeling of bubble column reactors , 1990 .

[11]  R.L.C. Flemmer,et al.  Turbulent circulation in bubble columns , 1987 .

[12]  Karl G. Anderson,et al.  Local turbulence model for predicting circulation rates in bubble columns , 1989 .

[13]  Milorad P. Dudukovic,et al.  Radioactive particle tracking technique for investigation of phase recirculation and turbulence in multiphase systems , 1992 .

[14]  Hean Luo,et al.  Turbulent circulation in bubble columns from eddy viscosity distributions of single-phase pipe flow , 1991 .

[15]  H. F. Svendsen,et al.  Local flow structures in internal loop and bubble column reactors , 1992 .