The confined impeller stirred tank (CIST): A bench scale testing device for specification of local mixing conditions required in large scale vessels

Machado, Márcio B.; Kresta, Suzanne M.

doi:10.1016/j.cherd.2013.06.025

Cited by 23 publications

(26 citation statements)

References 99 publications

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“…The confined impeller stirred tank (CIST) is a 1‐L bench‐scale mixing test cell. It was designed to replicate local mixing conditions particularly at the feed point for industrial mixing problems , . The CIST is filled with five or six impellers to provide uniform turbulence as illustrated in Fig.…”

Section: Introductionsupporting

confidence: 83%

“…The PBT‐UD configuration was able to sustain fully turbulent flow at a lower Re than the PBT‐D and PBT‐DU. The power numbers for the A310s and Intermigs were taken from Machado and Kresta as the same impellers are used here. Fig.…”

Section: Resultsmentioning

confidence: 55%

“…The power number per impeller is obtained by dividing the total power number per number of impellers in the CIST. A310 and Intermig data were measured by Machado and Kresta .…”

Section: Resultsmentioning

confidence: 85%

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Blend Time Measurement in the Confined Impeller Stirred Tank

et al. 2019

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An image processing technique is applied to measure the blend time in a confined impeller stirred tank (CIST). An acid-base reaction is used to track mixing. The blend time is defined as the time taken to 95 % or 99 % of the pixels change color from purple to yellow. Six sets of impellers are employed: Rushtons, A310s, pitched-blade turbines (PBTs; three different combinations of up-and downpumping), and Intermigs. Variation of the Reynolds number Re showed that the blend time becomes shorter with increasing Re and longer with higher viscosity. As Re drops below 225, compartmentalization becomes apparent and the decolorization percentage increases suddenly when the acid reaches each communication point between the impellers.

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Section: Introductionsupporting

confidence: 83%

Section: Resultsmentioning

confidence: 55%

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Blend Time Measurement in the Confined Impeller Stirred Tank

et al. 2019

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“…It is interesting to compare the profiles with the volume averaged dissipation rate of kinetic energy 〈 ε 〉 at 500 rpm. Since it was not measured, for estimation purposes it will be assumed that the power number is constant for this impeller at this rotational speed using Equation ( N p = 0.3,):

(〈〉, ε) = \frac{P}{ρ} = \frac{N_{p} N^{3} D^{5}}{V} = 0.184 m^{2} / s^{3}; \frac{〈ε〉}{N^{3} D^{2}} = 0.014

…”

Section: Resultsmentioning

confidence: 99%

“…Since shear rate is usually a controlling factor in processes such as flocculation or precipitation, numerous studies have focused on the determination of local shear rate and its relation with process performance in water . However, very few studies have made an in‐depth turbulence analysis of the A310 due to the difficulty of measuring the required turbulence terms. These studies confirmed that in water the A310 significantly dissipates energy in the impeller's swept volume (≈40% in Reference and ≈30% calculated with CFD).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic analysis of an axial impeller in a non‐Newtonian fluid through particle image velocimetry

2020

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The rheology of non-Newtonian fluids in agitated vessels is complex making equipment sizing more an art than a science. To increase our understanding and to resolve the data gap for computational fluid dynamics validation, we present a detailed particle image velocimetry study of the hydrodynamics of Carbopol encountered in a 70 L mechanically mixed (A310) tank at three different rotational speeds (100, 250, 500 rpm). Bulk flow visualizations show that the flow field below the impeller is highly influenced by the rheological behavior of the fluid. Moreover, an analysis of the shear rate and viscosity revealed important spatial heterogeneities. An estimation of the Reynolds number classified the rotational speeds as the onset of the transitional regime (100), in the transitional regime (250) and turbulent conditions (500 rpm). This data set consists of local mean and fluctuating velocities at different locations below the impeller, which are available for validation and further study. K E Y W O R D SCarbopol, mechanical mixing, particle image velocimetry, proper orthogonal decomposition, shear rate

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