Homogenization of liquids in tanks stirred by multiple impellers

Jahoda, M.; Machoň, Václav

doi:10.1002/ceat.270170205

Cited by 29 publications

(21 citation statements)

References 6 publications

(3 reference statements)

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“…The experiments were performed in a similar way to Part I [1], except for adjustments for multi-impeller systems, as described by Jahoda [8]. The differences from Part I are listed in this paragraph.…”

Section: Methodsmentioning

confidence: 99%

CFD Prediction of Flow and Homogenization in a Stirred Vessel: Part II Vessel with Three and Four Impellers

Kukuková

Moštěk

Jahoda

et al. 2005

Chem. Eng. Technol.

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This article deals with CFD simulations of flow inside stirred vessels equipped with three and four radial or axial impellers mounted on the same shaft. A comparison was made between simulated data and experiments for one-and two-impeller systems and was presented in Part I [1]. The effect of the lowest impeller off-bottom clearance, number of impellers used, and impeller type on the tracer distribution was studied. The simulations were mainly focused on the grid size and type and the analysis of the concentration curves in each impeller section. The predicted velocity fields, power and pumping numbers, concentration curves, and mixing times were validated with experimental data. The simulation results show the significant influence of the grid density on the velocity profiles and power and pumping numbers in contrast to the low impact on the concentration curves. A better prediction of the concentration curves was reached when radial impellers were used; the mixing times were generally over-predicted.

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Section: Methodsmentioning

confidence: 99%

CFD Prediction of Flow and Homogenization in a Stirred Vessel: Part II Vessel with Three and Four Impellers

Kukuková

Moštěk

Jahoda

et al. 2005

Chem. Eng. Technol.

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“…One important advantage of this model is that, unlike most compartment models (e.g. Mayr et al, 1993;Jahoda and Machon, 1994;Otomo et al, 1995), both its structure and parameters are closely related to the physical reality of flow generation, flow patterns and circulation flow rates that are present in the tank.…”

Section: Introductionmentioning

confidence: 98%

Scale‐up of mixing in gassed multi‐turbine agitated vessels

et al. 1998

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A mixing model previously developed for the determination of mixing time in gassed tanks stirred by multiple Rushton turbines (Vasconcelos et al., 1995) was verified for the additional scales of 0.39,0.56 and 0.72 m vessel diameter. It is now shown that the single adjusted parameter previously required by the model, the air-induced axial velocity parameter v,,, is scale-independent with an invariant value of 7 x m/s. Model simulations, with tank and turbine diameters and the number of stages as the only required parameters, deviate 5% on average from the experimentally determined mixing timeThe model is thus a valuable tool for scale-up of this type of vessels.Un modkle de mClange mis au point antkrieurement pour la dktermination du temps de mClange dans des rCservoirs en milieu aCrC agitCs par des turbines de Rushton multiples (Vasconselos et al., 1995), a Ctt vkrifiC pour de nouvelles Cchelles de diamktre de rkservoir de 0,39,0,56 et 0,72 m. I1 est maintenant montrC que le paramktre d'ajustement unique auparavant exigC par le modkle, soit le paramktre de vitesse axiale induite par l'air vp, est un invariant de 1'Cchelle dont la valeur est 7 x m/s. Des simulations utilisant comme paramktres uniques les diamktres de rkservoirs et de turbines et le nombre de phases, donnent des dCviations de 5% par rapport au temps de mClange to,os determink expCrimentalement. Le modkle est donc un outil valable pour la mise B I'Cchelle de ce type de rkservoirs.

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“…A major emphasis was put on analyzing gas-liquid systems, either experimentally or numerically [8,9]. Jahoda and colleagues have worked for more than a decade on analyzing the homogenization of reactors with high aspect ratios, agitated with multiple impellers [10][11][12][13]. Their experiments [10] and simulations [11][12][13] for multiple Rushton and pitched-blade turbines are an excellent base for understanding the flow field in slim reactors with H/T of up to 4.0.…”

Section: Introductionmentioning

confidence: 99%

Flow Field Analysis of Stirred Liquid‐Liquid Systems in Slim Reactors

Maaß¹,

Eppinger²,

Altwasser³

et al. 2011

Chem Eng & Technol

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Previous studies have shown the great potential, but also the great challenges, in handling slim reactors often used for polymerization reactions. Experiments and simulations were carried out in reactors with aspect-to-diameter ratios of up to 5, to test and to evaluate the mixing and dispersion efficiency for liquid-liquid systems of single-and multiple-stage impellers. Therefore, power consumption, mixing time and minimum dispersion speed were determined for five different stirrer types under turbulent conditions. It was found that the dimensionless mixing time is highly sensitive to the configuration of the impellers, with almost no dependency on the turbulent power number. Another focus was the analysis of the effect of the baffles. The influence of the baffle length in slim reactors on the mixing time and the macroscopic flow field was determined.

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Homogenization of liquids in tanks stirred by multiple impellers

Cited by 29 publications

References 6 publications

CFD Prediction of Flow and Homogenization in a Stirred Vessel: Part II Vessel with Three and Four Impellers

CFD Prediction of Flow and Homogenization in a Stirred Vessel: Part II Vessel with Three and Four Impellers

Scale‐up of mixing in gassed multi‐turbine agitated vessels

Flow Field Analysis of Stirred Liquid‐Liquid Systems in Slim Reactors

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