Stirring of a liquid in a stirred tank with an eccentrically located impeller

Karcz, J.; Cudak, Magdalena; Szoplik, J.

doi:10.1016/j.ces.2004.11.018

Cited by 87 publications

(57 citation statements)

References 6 publications

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“…The torque of the drive shaft T s is equal to the sum of moments of fluid force M, which can be given by dM rdF (6) where r is the radial distance and dF is the force acting on the impeller. The fluid force dF changes in time t and for the unsteadily rotating impeller can be expressed by the…”

Section: Methodsmentioning

confidence: 99%

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

Woziwodzki

2011

Chem Eng & Technol

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Usually, mixing is carried out in a vessel with four baffles and a single impeller. In some applications, however, the use of a baffled vessel is not recommended. One of the stirring methods used instead is unsteady agitation with forward-reverse rotating impellers. The aim of this work was to characterize the agitation characteristics in a baffled and an unbaffled vessel with a turbine impeller. Mixing time and mixing power were evaluated in relation to the presence of baffles and the frequency of forward-reverse rotation. It was found that the frequency of oscillation does not affect either the mixing time and mixing power values or the drag and added mass coefficients. Power requirements and mixing time were higher compared to the steady mixing conditions in a baffled vessel. The results showed that it is not recommended to use baffles because they have no influence on unsteady mixing.

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Section: Methodsmentioning

confidence: 99%

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

Woziwodzki

2011

Chem Eng & Technol

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“…Indeed, many authors have shown that, in turbulent flow, shaft eccentricity is equivalent to baffling (Joosten et al, 1977;Nishikawa et al, 1979;Novak et al, 1982;King and Muskett, 1985;Hall et al, 2004Hall et al, , 2005bKarcz and Szoplik, 2004;Karcz et al, 2005;Montante et al, 2006). Nishikawa et al (1979), Karcz and Szoplik (2004) and Karcz et al (2005) have shown that for axial and radial type impellers the mixing time decreases with the increase of the shaft eccentricity. Many studies also report increased power with the shaft eccentricity with both axial and radial type impellers (Nishikawa et al, 1979;Novak et al, 1982;Karcz et al, 2005).…”

Section: Introductionmentioning

confidence: 94%

Effect of shaft eccentricity on the laminar mixing performance of a radial impeller

2008

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The effects of impeller eccentricity and Reynolds number on the mixing performance were studied for Rushton turbine stirred tank systems operated in the laminar regime (Re < 10). A digital image analysis of an acid-base decolourization reaction was used to characterize the mixing efficiency. Results show that both parameters have remarkable effects on the destruction of the toroidal segregated regions surrounding the Rushton turbine in laminar flow. Criteria are given to prevent the formation of these segregated regions in a tank. It is also shown that shaft eccentricity does not impact on the impeller power consumption.Les effets de l'excentrage du mobile d'agitation et du nombre de Reynolds sur les performances d'une turbine Rushton opérée en régime laminaire (Re < 10) ontétéétudiés. Une analyse d'images numériques issues d'une réaction de décoloration acide-base aété utilisée pour caractériser l'efficacité du mélange. Les résultats montrent que ces deux paramètres ont des effets remarquables sur la destruction des zones toroïdales non mélangées entourant la turbine Rushton en régime laminaire. Des critères ont ainsiétéétablis afin d'éviter la formation de ces zones ségrégées dans une cuve. De plus, il aété montré que l'excentrage de l'arbre n'a pas d'impact sur la consommation de puissance de l'agitateur.

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“…The baffles can enhance the mixing performance remarkably and have been widely used, the off-center mounting has also been investigated thoroughly [4,5] and the uncircumferentially symmetrical tanks have recently been studied [6][7][8]. However, the most desirable method is to know how to insert the traditional impeller into a vessel because it does not cost so much.…”

Section: Introductionmentioning

confidence: 99%

Laminar Mixing in Stirred Tank Agitated by an Impeller Inclined

Takahashi

Sugo

Takahata

et al. 2012

International Journal of Chemical Engineering

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The mixing performance in a vessel agitated by an impeller that inclined itself, which is considered one of the typical ways to promote mixing performance by the spatial chaotic mixing, has been investigated experimentally and numerically. The mixing time was measured by the decolorization method and it was found that the inclined impeller could reduce mixing time compared to that obtained by the vertically located impeller in laminar flow region. The effect of eccentric position of inclined impeller on mixing time was also studied and a significant reduction of mixing time was observed. To confirm the experimental results, the velocity profiles were calculated numerically and two novel numerical simulation methods were proposed.

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Stirring of a liquid in a stirred tank with an eccentrically located impeller

Cited by 87 publications

References 6 publications

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

Effect of shaft eccentricity on the laminar mixing performance of a radial impeller

Laminar Mixing in Stirred Tank Agitated by an Impeller Inclined

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