Liquid Homogenization Characteristics in Vessels Stirred with Multiple Rushton Turbines Mounted at Different Spacings: CFD Study and Comparison with Experimental Data

The purpose of this work is to investigate the capability of the currently available CFD tools to correctly forecast the homogenization process in a baffled vessel stirred with sets of identical Rushton turbines mounted with different spacings. The results of the simulations are compared with experimental data for the validation of the computational procedure. The simulations provide a good prediction of the time evolution of tracer dispersion inside the vessel volume for all the geometrical configurations. The differences in mixing performance due to flow variations occurring as a result of the modification of the impeller number and spacing are correctly forecasted.

[1]  K. C. Lee,et al.  Numerical simulations of the dependency of flow pattern on impeller clearance in stirred vessels , 2001 .

[2]  Michael Yianneskis,et al.  The Variation of Flow Pattern and Mixing Time with Impeller Spacing in Stirred Vessels with Two Rushton Impellers , 1992 .

[3]  James Y. Oldshue,et al.  Biotechnology processes : scale-up and mixing , 1987 .

[4]  A. Nienow,et al.  CFD Study of Homogenization with Dual Rushton Turbines—Comparison with Experimental Results: Part I: Initial Studies☆ , 2000 .

[5]  Silvio Sicardi,et al.  Effect of the stirrer clearance on particle suspension in agitated vessels , 1981 .

[6]  Václav Linek,et al.  Gas-liquid mass transfer in vessels stirred with multiple impellers—I. Gas-liquid mass transfer characteristics in individual stages , 1996 .

[7]  Setsuro Hiraoka,et al.  Power Consumption and Mixing Time in an Agitated Vessel with Double Impeller , 2001 .

[8]  Predrag Horvat,et al.  Mixing-models applied to industrial batch bioreactors , 1993 .

[9]  G. Montante,et al.  CFD simulations and experimental validation of homogenisation curves and mixing time in stirred Newtonian and pseudoplastic liquids , 2005 .

[10]  Cui Yq,et al.  Compartment Mixing Model for Stirred Reactors with Multiple Impellers , 1996 .

[11]  Yasuhiro Murakami,et al.  Turbulent mixing in baffled stirred tanks with vertical‐blade impellers , 1988 .

[12]  Alberto Brucato,et al.  Numerical prediction of flow fields in baffled stirred vessels: A comparison of alternative modelling approaches , 1998 .

[13]  B. Launder,et al.  The numerical computation of turbulent flows , 1990 .

[14]  Jorge M. M. Barata,et al.  Alternative compartment models of mixing in tall tanks agitated by multi-Rushton turbines , 1997 .

[15]  K. C. Lee,et al.  An experimental study of double-to-single-loop transition in stirred vessels , 1999 .

[16]  Peter Vrábel,et al.  Compartment Model Approach: Mixing in Large Scale Aerated Reactors with Multiple Impellers , 1999 .

[17]  Joji Takahashi,et al.  Circulation Time and Degree of Fluid Exchange between Upper and Lower Circulation Regions in a Stirred Vessel with a Dual Impeller , 1981 .

[18]  I. Yimer,et al.  Estimation of the turbulent Schmidt number from experimental profiles of axial velocity and concentration for high-reynolds-number jet flows , 2002 .

[19]  Alvin W. Nienow,et al.  CFD Study of Homogenization with Dual Rushton Turbines—Comparison with Experimental Results: Part II: The Multiple Reference Frame☆ , 2000 .

[20]  Michael Yianneskis,et al.  Hydrodynamic characteristics of dual Rushton impeller stirred vessels , 1996 .

[21]  Kouji Nagata,et al.  The difference in turbulent diffusion between active and passive scalars in stable thermal stratification , 2001, Journal of Fluid Mechanics.

[22]  Alvin W. Nienow,et al.  Gas–liquid dispersion with dual Rushton impellers , 1989 .

[23]  Alberto Brucato,et al.  Prediction of flow fields in a dual-impeller stirred vessel , 1999 .

[24]  Jorge M. M. Barata,et al.  Mixing in gas-liquid contactors agitated by multiple turbines , 1995 .

[25]  Catherine Xuereb,et al.  3-D hydrodynamics generated in a stirred vessel by a multiple-propeller system , 1997 .

[26]  J. P. V. Doormaal,et al.  ENHANCEMENTS OF THE SIMPLE METHOD FOR PREDICTING INCOMPRESSIBLE FLUID FLOWS , 1984 .

[27]  Alvin W. Nienow,et al.  Mixing in large-scale vessels stirred with multiple radial or radial and axial up-pumping impellers: modelling and measurements , 2000 .

[28]  Silvio Sicardi,et al.  Mixing time in vessels stirred by multiple impeller , 1991 .

[29]  Andrew T. Hsu,et al.  The effect of Schmidt number on turbulent scalar mixing in a jet-in-crossflow , 1999 .

[30]  Ivan Fořt,et al.  Liquid circulation in a cylindrical baffled vessel of high height/diameter ratio with two impellers on the same shaft , 1987 .

[31]  Milan Jahoda,et al.  Homogenization of liquids in tanks stirred by multiple impellers , 1994 .

[32]  P. Bradshaw,et al.  Turbulence Models and Their Application in Hydraulics. By W. RODI. International Association for Hydraulic Research, Delft, 1980. Paperback US $15. , 1983, Journal of Fluid Mechanics.