Scalar mixing measurements in batch operated stirred tanks

Authors

  • M. F. W. Distelhoff,

    1. Imperial College of Science Technology and Medicine, Mechanical Engineering Department, Exhibition Road, London SW7 2BX, U.K
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  • A. J. Marquis,

    Corresponding author
    1. Imperial College of Science Technology and Medicine, Mechanical Engineering Department, Exhibition Road, London SW7 2BX, U.K
    • Imperial College of Science Technology and Medicine, Mechanical Engineering Department, Exhibition Road, London SW7 2BX, U.K
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  • J. M. Nouri,

    1. Imperial College of Science Technology and Medicine, Mechanical Engineering Department, Exhibition Road, London SW7 2BX, U.K
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  • J. H. Whitelaw

    1. Imperial College of Science Technology and Medicine, Mechanical Engineering Department, Exhibition Road, London SW7 2BX, U.K
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Abstract

An LIF technique was used to obtain unobtrusive measurements of scalar concentration as a function of time and mixing times in a fully baffled batch operated mixing vessel agitated by five forms of impeller (Rushton, ‘bucket’, six bladed 45°-and 60°-pitched blade, hyperboloid).

The mixing time was comparable to the time required for the dye/scalar to be transported from the top of the vessel to the bottom part plus the time required for a further two rotations of the bulk flow in the circumferential direction. At constant power input the mixing times for similar impellers were similar, although different for different types.

Abstract

On a utilisé une technique LIF afin d'obtenir des mesures non intrusives de concentration scalaire en fonction du temps et des temps de mélange dans une cuve agitée munie de contrepales pour cinq types de turbines (Rushton, “à abues”, à 6 pales inclinées à 45° et 60°, hyperboloïdes) en régime discontinu.

Le temps de mélange est comparable au temps requis pour le transport du colorant/scalaire depuis le sommet du réservoir jusqu'à sa base plus le temps requis pour encore deux rotations du coeur de l'écoulement dans la direction circonférentielle. À puissance constante, les temps de mélange pour des turbines semblables sont similaires, mais ils différent lorsque les turbines sont de différents types.

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