Scale up study of retreat curve impeller stirred tanks using LDA measurements and CFD simulation.

Abstract In this paper, scale up effects have been investigated for three geometrically similar laboratory scale vessels of 0.5, 2 and 20 l with retreat curve impellers and cylindrical baffles, which mimic reactors widely used in the pharmaceutical and fine chemical industries, using CFD simulations. The convergence of fully three-dimensional, time-dependent numerical computations has been monitored to ensure the simulations reached quasi-steady state. CFD results have then been validated using LDA measurements and empirical power consumption literature data. The comparisons of power number, discharge flow number, secondary circulation flow number and pumping efficiency at three different scales suggest that the selection of scale of a laboratory vessel has little effect on the macro mixing performance for optimisation of the configuration and operating conditions of an industrial scale reactor.

[1]  Stuart E. Rogers,et al.  Steady and unsteady computation of impeller‐stirred reactors , 1996 .

[2]  Vivek V. Ranade,et al.  Trailing Vortices of Rushton Turbine: PIV Measurements and CFD Simulations with Snapshot Approach , 2001 .

[3]  F. Menter.  Two-equation eddy-viscosity turbulence models for engineering applications , 1994 .

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

[5]  Alfredo Soldati,et al.  Fluid Dynamic Efficiency and Scale-up of a Retreated Blade Impeller CSTR , 2002 .

[6]  Vivek V. Ranade,et al.  An efficient computational model for simulating flow in stirred vessels: a case of Rushton turbine , 1997 .

[7]  Zdzisław Jaworski,et al.  THE EFFECT OF SIZE, LOCATION AND PUMPING DIRECTION OF PITCHED BLADE TURBINE IMPELLERS ON FLOW PATTERNS: LDA MEASUREMENTS AND CFD PREDICTIONS , 2001 .

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

[9]  Kevin J. Roberts,et al.  LDA measurements and CFD modeling of a stirred vessel with a retreat curve impeller , 2004 .

[10]  Michael Yianneskis,et al.  Experiments and predictions of the transition of the flow pattern with impeller clearance in stirred tanks , 2001 .

[11]  Alfredo Soldati,et al.  Time-dependent finite-volume simulation of the turbulent flow in a free-surface CSTR , 2001 .

[12]  Kevin J. Myers,et al.  The laminar and turbulent flow pattern of a pitched blade turbine , 1996 .

[13]  Alfredo Soldati,et al.  Appraisal of Fluid Dynamic Efficiency of Retreated-Blade and Turbofoil Impellers in Industrial-Size CSTRs , 2002 .

[14]  S. Nagata.  Mixing: Principles and Applications , 1975 .

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

[16]  Stuart E. Rogers,et al.  Steady-state modeling and experimental measurement of a baffled impeller stirred tank , 1995 .