The simplest stirred tank for laminar mixing: Mixing in a vessel agitated by an off-centered angled disc

Authors

  • D. Bulnes-Abundis,

    1. Centro de Biotecnología-FEMSA, Escuela de Biotecnología y Alimentos, Tecnológico de Monterrey at Monterrey, Monterrey, NL, México
    Search for more papers by this author
  • M. M. Alvarez

    Corresponding author
    • Centro de Biotecnología-FEMSA, Escuela de Biotecnología y Alimentos, Tecnológico de Monterrey at Monterrey, Monterrey, NL, México
    Search for more papers by this author

Correspondence concerning author should be addressed to M. M. Alvarez at mario.alvarez@itesm.mx.

Abstract

We study the mixing structure, mixing performance, and short term dynamics in round bottomed laminar tanks agitated by an eccentrically located angled disc. We define eccentricity (E = e/R) as the ratio of the distance of the axis of rotation from the center line of the tank (e) and the tank radius (R). The structural and dynamic features observed at different eccentricity values were compared using planar laser-induced fluorescence techniques and computational fluid dynamics calculations. A Poincaré analysis demonstrates the chaotic nature of the flow induced by eccentricity. Practically globally chaotic conditions are observed for E = 0.42 and E = 0.50, with mixing times of 5–8 min at Re = 416. We study the effect of different injection points on the short-term mixing dynamics and we calculate axial flow rates and Power numbers. Stirred tanks agitated by an eccentrically located angled disc are a simple and cost effective system for laminar mixing applications. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3092–3108, 2013

Ancillary