Determination of correlations to predict the minimum agitation speed for complete solid suspension in agitated vessels

Armenante, Piero M.; Nagamine, Ernesto Uehara; Susanto, Jessyca

doi:10.1002/cjce.5450760310

Cited by 65 publications

(33 citation statements)

References 20 publications

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“…At lower solid loading, our results are closer to those estimated using Zweitering's 1 correlation. At higher solid loading (>3%v/v), our results are closer to those estimated using Raghav Rao et al 2 and Armanante et al 6 correlations. The wall pressure fluctuation technique used in this work can potentially be used for carrying out measurements of just suspension impeller speed, suspension regimes, and circulation time in large, opaque industrial systems.…”

Section: Comparative Studysupporting

confidence: 92%

Solid Suspension and Liquid Phase Mixing in Solid−Liquid Stirred Tanks

Sardeshpande

Sagi

Juvekar

et al. 2009

Ind. Eng. Chem. Res.

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Stirred tanks are widely used in chemical process industries for catalytic reactions, dissolution of solids, crystallization, and so on. In designing and optimizing such processes, suspension quality of slurry is an important parameter. Suspension quality depends upon complex interactions of impeller generated flow, turbulence, and solid loading. Most of the earlier work on solid suspension focuses on identifying critical impeller speed for just suspension of solids (N js ). In this study, apart from N js , aspects like cloud height and liquid phase mixing in solid-liquid suspensions were also studied. A new way of characterizing solid-liquid suspensions and liquid phase mixing using nonintrusive wall pressure fluctuation measurements has been developed. Systematic experimental data on N js , cloud height, power consumption, mixing time, and circulation time over a range of solid volume fraction and impeller speeds have been presented here. The results and discussion presented here will have useful implications for designing solid-liquid stirred tanks.

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Section: Comparative Studysupporting

confidence: 92%

Solid Suspension and Liquid Phase Mixing in Solid−Liquid Stirred Tanks

Sardeshpande

Sagi

Juvekar

et al. 2009

Ind. Eng. Chem. Res.

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“…One major goal of PI is to intensify the processes that require handling of high‐concentration particles, catalysts, or droplets in complex slurry reactors 2, 3. Handling of solids in liquids in the processing units is involved in about 80 % of operations in various industries, ranging from leaching to homogenizing of catalysts 4–6. In particular, experimental and theoretical information regarding homogeneous suspensions or mixing of high‐concentration slurries seems rather rare in the literature.…”

Section: Introductionmentioning

confidence: 99%

Optimized Stirred Reactor for Enhanced Particle Dispersion

et al. 2016

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Homogeneous dispersion of particles is crucial for many processes where the reaction rate is highly dependent on relative rates of mixing or degree of homogenization. These processes include crystallization, polymerization, and some mineral-refining processes. Complete particle dispersion in high-concentration slurries is researched experimentally and numerically. Computation fluid dynamics results suggest that cloud height is an excellent indicator for mixing homogeneity, and energy efficiency can be enhanced by removing baffles over a range of solids concentrations under the complete dispersion condition. The power required to maintain a high cloud height in a stirred tank can be predicted via a simple power number analysis. The proposed unbaffled design can be potentially beneficial to some industrial processes like crystallization.

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“…Such a liquid flow would be important for a system in which the bottom region is emphasised, for example, a system involving off-bottom suspension of solid particles (Ibrahim and Nienow, 1996;Armenante et al, 1998). Figure 8 shows the time courses of the velocity components, v r and v Â , in the circulation flow determined for the position near the vessel bottom (the axial distance, Z = 5 mm) with the radial distance, R, as a parameter.…”

Section: Liquid Flow Within the Vesselmentioning

confidence: 99%

“…off-bottom suspension of solid particles (Ibrahim and Nienow, 1996;Armenante et al, 1998), mixing of liquid phase (Ochieng et al, 2008), etc.…”

Section: Introductionmentioning

confidence: 99%

Effect of impeller clearance on liquid flow within an unbaffled vessel agitated with a forward–reverse rotating impeller

et al. 2009

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For an unbaffled agitated vessel with an unsteadily forward-reverse rotating impeller whose rotation proceeds with repeated acceleration, deceleration, and stop-reverse processes, liquid flow was studied through visualisation and measurement using particle tracking velocimetry (PTV). A disk turbine impeller with six flat blades was used with varied height settings. The impeller clearance and its forward-reverse rotation cycle characterised the impeller region flow: the radially outward flow in the deceleration process for the larger clearance relative to the vessel diameter of 1/3, and the axially downward flow in the acceleration process for the smaller clearance relative to the vessel diameter of 1/8. The flow patterns within the vessel resulting from the impeller's larger and smaller clearances were outlined, respectively, by double loops and a single loop of circulation, resembling the pattern produced by unidirectionally rotating turbine-type impellers. The discharge flow was revealed to contain a comparable level of periodic circumferential velocity component, irrespective of the impeller clearance.On aétudié l'écoulement liquide par visualisation et mesure en utilisant la vélocimétrie avec poursuite de trajectoire pour une cuve non compartimentée et agitée avec un agitateur rotatif avant-arrière non stable dont la rotation est composée de périodes répétées d'accélération, de ralentissement et d'arrêt-marche arrière. Un agitateurà six pales plates aété utilisé avec quatre réglages de hauteur différents. Le dégagement de l'agitateur et son cycle de rotation avant-arrière caractérisaient l'écoulement liquide dans la région de l'agitateur : l'écoulement radial vers l'extérieur dans le processus de décélération pour le dégagement le plus important par rapport au diamètre de la cuve de 1/3 et l'écoulement axial vers le bas dans le processus d'accélération pour le dégagement le plus petit par rapport au diamètre de la cuve de 1/8. Les modèles d'écoulement intérieurs de la cuve résultant du plus grand et du plus petit dégagements de l'agitateur ontété décrits, respectivement, par des doubles boucles et une simple boucle de circulation, ce qui ressemble au modèle produit par des agitateursà hélice unidirectionnels. On a révélé que l'écoulement de sortie contenait un niveau comparable de vélocité périodique périphérique, indépendamment du dégagement de l'agitateur.

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Determination of correlations to predict the minimum agitation speed for complete solid suspension in agitated vessels

Cited by 65 publications

References 20 publications

Solid Suspension and Liquid Phase Mixing in Solid−Liquid Stirred Tanks

Solid Suspension and Liquid Phase Mixing in Solid−Liquid Stirred Tanks

Optimized Stirred Reactor for Enhanced Particle Dispersion

Effect of impeller clearance on liquid flow within an unbaffled vessel agitated with a forward–reverse rotating impeller

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