Effect of low off-bottom impeller clearance on the minimum agitation speed for complete suspension of solids in stirred tanks

Armenante, Piero M.; Nagamine, Ernesto Uehara

doi:10.1016/s0009-2509(98)00001-3

Cited by 114 publications

(59 citation statements)

References 26 publications

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“…This was in contrast with previous works (see for example Conti et al, 1981) which reported a clearance of transition independent on D/T. For instance Armenante & Nagamine (1998) found the flow pattern transition to occur at 0.16 < C/T < 0.19 for a Rushton turbine with a diameter D = 0.217T and at 0.13 < C/T < 0.16 for a D = 0.348T RT. For the flat blade turbine the clearances at which the transition took places were higher, being of 0.22-0.24 and 0.19-0.21 for the two impeller sizes D = 0.217T and D = 0.348T, respectively.…”

Section: Classification Of Flow Instabilitiescontrasting

confidence: 99%

“…Bakker et al (1998) reported that the flow pattern generated by either a PBT or a three-blade high efficiency impeller depended on C/T and D/T, influencing the suspension of the particles. Armenante & Nagamine (1998) determined the Njs and the power consumption of four impellers set at low off-bottom clearances, typically C < T/4. For radial impellers, i.e.…”

Section: Classification Of Flow Instabilitiesmentioning

confidence: 99%

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Flow Instabilities in Mechanically Agitated Stirred Vessels

Galletti¹,

Brunazzi²

2011

Hydrodynamics - Advanced Topics

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Section: Classification Of Flow Instabilitiescontrasting

confidence: 99%

Section: Classification Of Flow Instabilitiesmentioning

confidence: 99%

Flow Instabilities in Mechanically Agitated Stirred Vessels

Galletti¹,

Brunazzi²

2011

Hydrodynamics - Advanced Topics

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“…Mixing in this zone depends on the type of flow pattern generated by the agitator. Sharma and Shaikh (2003) confirmed the results of Armenante and Nagamine (1998) by showing that the flow pattern from an axial flow impeller is more favorable for suspension compared to the flow pattern produced by a radial flow impeller. They demonstrated that the flow pattern of an axial impeller changes with increasing off-bottom clearance to a radial impeller.…”

Section: Review On Mixingsupporting

confidence: 68%

Sediment Evacuation from Reservoirs through Intakes by Jet-Induced Flow

2015

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Reservoir sedimentation is considered as a sustainability problem. A concept getting down to the root of the cause was developed and tested in laboratory experiments. The idea is to maintain sediment in suspension, i.e., avoiding its settling near the dam by generating a jet induced artificial flow field and related turbulence (rotational flow), enabling the release of suspended sediment through the power intake. Therefore, a perpendicular jet configuration consisting of four jets arranged in a horizontal plane was investigated in a rectangular basin equipped with an outlet structure. The influence of its geometric parameters and the jet discharge on the sediment release was analyzed in detail. The flow pattern and its effect on the sediment release efficiency were evaluated, by measurements of turbidity and flow velocity. Depending on experiment duration and discharge, an ideal parameter set was identified resulting in a release efficiency between 1.5 and 2 compared to the reference case without jets.

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“…Impeller off-bottom clearance is an important geometric parameter and its effect on flow patterns and power consumption in batch stirred tanks has been a subject of several experimental and computational investigations (Nienow, 1968;Conti et al, 1981;Ibrahim and Nienow, 1995;Armenante and Nagamire, 1998;Montante et al, 1999Montante et al, , 2001a. The most important finding of these studies is that below a certain value of clearance even a radial flow impeller behaves like an axial flow impeller.…”

Section: Introductionmentioning

confidence: 99%

CFD modeling of pilot-scale pump-mixer: Single-phase head and power characteristics

Singh

Mahajani

Shenoy

et al. 2007

Chemical Engineering Science

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The present work involves single-phase computational fluid dynamics (CFD) simulations of continuous flow pump-mixer employing topshrouded Rushton turbines with trapezoidal blades. Baffle-impeller interaction has been modeled using sliding mesh and multiple reference frame approaches. Standard k-model has been used for turbulence modeling. Several CFD runs representing different combinations of geometric and process parameters have been carried out. Results of CFD simulations have been used to find out two macroscopic performance parameters of pump-mixer-power consumption and head generated by the impeller. The simulation results have been compared with the experimental data obtained on a pilot-scale setup. Good agreement between CFD predictions and experimental results is observed. In most cases, sliding mesh approach is found to perform better than multiple reference frame approach. Details from CFD simulations have been used to have an insight into the pumping action of the impeller.

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Effect of low off-bottom impeller clearance on the minimum agitation speed for complete suspension of solids in stirred tanks

Cited by 114 publications

References 26 publications

Flow Instabilities in Mechanically Agitated Stirred Vessels

Flow Instabilities in Mechanically Agitated Stirred Vessels

Sediment Evacuation from Reservoirs through Intakes by Jet-Induced Flow

CFD modeling of pilot-scale pump-mixer: Single-phase head and power characteristics

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