Solid-Liquid Flow at Dilute Concentrations in an Axially Stirred Vessel Investigated Using Particle Image Velocimetry

Virdung, Torbjörn; Rasmuson, Anders

doi:10.1080/00986440701554988

Cited by 23 publications

(11 citation statements)

References 20 publications

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“…For example, Guiraud et al (1997) found that the axial and radial rms velocities from a down‐pumping propeller were unaffected by the presence of 253 µm particles at 0.5 vol.%. On the other hand, Virdung and Rasmuson (2007, 2008) found that with a pitched‐blade turbine, rms enhancement occurred for 1, 1.5, and 2 mm particles again at 0.5 vol.%. In contrast to this, Micheletti and Yianneskis (2004) using two sizes of Rushton turbines reported rms suppression in the impeller region of the tank (which extended out to the equivalent feed point used here) by up to 70% when dispersing 186 µm particles, again at 0.5 vol%.…”

Section: Literature Surveymentioning

confidence: 99%

Micromixing in two‐phase (G‐L and S‐L) systems in a stirred vessel

et al. 2011

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The literature on micromixing and local-specific energy dissipation rate,ε T (on which it depends), for two-phase systems is limited and conflicting. Here, the competitive iodide/iodate reaction scheme has been used to study the effect of particles and gas flow rate on micromixing in a Rushton turbine agitated vessel. Gassing rates up to 1.5 vvm did not show any effect on product distribution compared to the ungassed at constant mean-specific energy dissipation rate (ε T ) g =ε T for a feeding near the impeller. Near the upper liquid surface, micromixing improved with increasing flow rate because it increased fluid turbulence. These results confirm the limited literature. With 500 m glass beads at concentrations up to 2.5 wt.%, micromixing was unaffected near the impeller and near the surface. The related literature is very unclear and it is difficult to draw any precise conclusions. At ∼12 wt.% when cloud formation was observed, micromixing was significantly worse, especially, it is shown for the first time, in the clear layer above the cloud. The latter finding is significant for processes such as precipitation where micromixing determines the particle characteristics.

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Section: Literature Surveymentioning

confidence: 99%

Micromixing in two‐phase (G‐L and S‐L) systems in a stirred vessel

et al. 2011

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“…As for investigations about the flow field, laser‐based optical imaging techniques such as Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV) are the most widely used. In applying these techniques to solid‐liquid systems, a main limiting factor is the solids concentration which—in the studies referred to here—was less than 1% by volume .…”

Section: Introductionmentioning

confidence: 99%

“…Virdung et al used a mixture of benzyl alcohol/ethanol and glass spheres as the continuous and dispersed phases, respectively, to investigate the axial velocities and turbulence levels in a stirred tank by LDA with a maximum solids volume fraction up to 9%. With the same continuous and dispersed phases, Virdung et al also measured the velocities of both phases up to 1.5% solids by volume using PIV combined with image analysis to separate the particles and liquid in their camera frames. Gabriele et al used p‐cymene and PMMA spheres as the continuous and dispersed phases, respectively, to investigate the turbulence properties of the fluid in a high throughput stirred vessel for both up‐pumping and down‐pumping configurations by PIV with up to 5% (by volume) particles.…”

Section: Introductionmentioning

confidence: 99%

“…In this way, Kohnen et al found that the TKE increased in the areas near the impeller and decreased in the remaining areas with the rise of solids fractions. However, the size of the particles as well as the resolution of velocity vectors in most investigations are less than or equal to one millimeter, which means that the flow field around the particles is not resolved by the experiments. In the study by Gabriele et al, the diameter of the particles was 1.5 mm whereas the velocity vectors resolution was 171 μm with the minimum interrogation area of 16 × 16 pixels and 50% overlap.…”

Section: Introductionmentioning

confidence: 99%

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Particle‐resolved PIV experiments of solid‐liquid mixing in a turbulent stirred tank

Gao

et al. 2017

AIChE Journal

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Particle Image Velocimetry (PIV) experiments on turbulent solid-liquid stirred tank flow with careful refractive index matching of the two phases have been performed. The spatial resolution of the PIV data is finer than the size of the spherical, uniformly sized solid particles, thereby providing insight in the flow around individual particles. The impeller is a down-pumping pitch-blade turbine. The impeller-based Reynolds number has been fixed to Re 5 10 4 . Overall solids volume fractions up to 8% have been investigated. The PIV experiments are impeller-angle resolved, that is, conditioned on the angular position of the impeller. The two-phase systems are in partially suspended states with an inhomogeneous distribution of solids: high solids loadings near the bottom and near the outer walls of the tank, much less solids in the bulk of the tank. The liquid velocity fields show very strong phase coupling effects with the particles increasingly attenuating the overall circulation patterns as well as the liquid velocity fluctuation levels when the solids volume fraction is increased.

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“…Liquid mixing are widely used processes in the majority of industry. On that account an assessment of flow behaviour in a stirred tank is the subject of numerous experimental and numerical studies (Virdung et al, 2008;Blais et al, 2016;Sharp et al, 2001;Long and Nong, 2017;Malik and Pakzad, 2018;Wang et al, 2016;Lamotte et al, 2018). The change in the quality of the mixing process can be achieved by changing many parameters for example: type and number of stirrer, rotation speed of stirrer, geometry of the tank or an orientation of the stirrer in the tank (Kresta et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Flow pattern identification in a rectangular tank comprising stirrer in an off-center orientation

2018

Engineering Mechanics

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In this paper the results of experimental research of flow pattern identification during mixing process using a stirrer in an off-center orientation in a rectangular tank were presented. The research applied Digital Particle Image Velocimetry (DPIV) technique. The velocity vector fields with regard to the stirrer orientation and rotational speed of the mixing process were determined and they were subsequently applied for identification and assessment of liquid flow pattern in a tank. Also the assessment of flow pattern by statistical non-uniform coefficient was introduced. The relation between the rotational speed of the stirrer and stirrer orientation for mixing performance were determined. The study demonstrated some lack of analogy in certain areas of liquid behavior during the mixing process in the tank with rectangular crosssection and circular cross-section.

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Solid-Liquid Flow at Dilute Concentrations in an Axially Stirred Vessel Investigated Using Particle Image Velocimetry

Cited by 23 publications

References 20 publications

Micromixing in two‐phase (G‐L and S‐L) systems in a stirred vessel

Micromixing in two‐phase (G‐L and S‐L) systems in a stirred vessel

Particle‐resolved PIV experiments of solid‐liquid mixing in a turbulent stirred tank

Flow pattern identification in a rectangular tank comprising stirrer in an off-center orientation

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