Comparative study of different mixing strategies in small high throughput experimentation reactors

Hall, Jonathan; Barigou, Mostafa; Simmons, Mark; Stitt, E. Hugh

doi:10.1016/j.ces.2004.10.045

Cited by 37 publications

(28 citation statements)

References 22 publications

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“…Bulnis-Abundis and Alvarez, 2013), in small scale stirred vessels (Hall et al, 2005), reactive flows in stirred tanks (Hu et al, 2012), unbaffled stirred vessels (Busciglio et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Flow field and homogenization time assessment in continuously-fed stirred tanks

Busciglio

Montante

Paglianti

2015

Chemical Engineering Research and Design

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“…Bulnis-Abundis and Alvarez, 2013), in small scale stirred vessels (Hall et al, 2005), reactive flows in stirred tanks (Hu et al, 2012), unbaffled stirred vessels (Busciglio et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Flow field and homogenization time assessment in continuously-fed stirred tanks

Busciglio

Montante

Paglianti

2015

Chemical Engineering Research and Design

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“…Indeed, many authors have shown that, in turbulent flow, shaft eccentricity is equivalent to baffling (Joosten et al, 1977;Nishikawa et al, 1979;Novak et al, 1982;King and Muskett, 1985;Hall et al, 2004Hall et al, , 2005bKarcz and Szoplik, 2004;Karcz et al, 2005;Montante et al, 2006). Nishikawa et al (1979), Karcz and Szoplik (2004) and Karcz et al (2005) have shown that for axial and radial type impellers the mixing time decreases with the increase of the shaft eccentricity.…”

Section: Introductionmentioning

confidence: 99%

Effect of shaft eccentricity on the laminar mixing performance of a radial impeller

2008

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The effects of impeller eccentricity and Reynolds number on the mixing performance were studied for Rushton turbine stirred tank systems operated in the laminar regime (Re < 10). A digital image analysis of an acid-base decolourization reaction was used to characterize the mixing efficiency. Results show that both parameters have remarkable effects on the destruction of the toroidal segregated regions surrounding the Rushton turbine in laminar flow. Criteria are given to prevent the formation of these segregated regions in a tank. It is also shown that shaft eccentricity does not impact on the impeller power consumption.Les effets de l'excentrage du mobile d'agitation et du nombre de Reynolds sur les performances d'une turbine Rushton opérée en régime laminaire (Re < 10) ontétéétudiés. Une analyse d'images numériques issues d'une réaction de décoloration acide-base aété utilisée pour caractériser l'efficacité du mélange. Les résultats montrent que ces deux paramètres ont des effets remarquables sur la destruction des zones toroïdales non mélangées entourant la turbine Rushton en régime laminaire. Des critères ont ainsiétéétablis afin d'éviter la formation de ces zones ségrégées dans une cuve. De plus, il aété montré que l'excentrage de l'arbre n'a pas d'impact sur la consommation de puissance de l'agitateur.

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“…Three separate virtual probe locations were utilised during image analysis in order to determine final mixing time, each probe consisting of 40 (20 x 20) pixels; these are shown on Figure 2b. A calibration of the local greyscale value to dye concentration was performed to ensure all recorded greyscale values were linearly related to concentration; see Hall et al (2005) for further details. Raw data images were preprocessed to eliminate the effect of diminishing laser light intensity across the geometry using a pixelby-pixel calibration and then analysed using a bespoke MATLAB code.…”

Section: Planar Laser-induced Fluorescence (Plif)mentioning

confidence: 99%

Mixing of Newtonian and viscoelastic fluids using “butterfly” impellers

Ramsay

Simmons

Ingram

et al. 2016

Chemical Engineering Science

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The mixing of high viscosity and viscoelastic fluids may be performed in industry using a "butterfly" impeller, which has received scant attention. This paper describes the characterisation of these impellers using both Newtonian and viscoelastic (Boger) fluids with an identical base viscosity under laminar flow conditions in batch tanks without baffles. Measurements are made using two rotational speeds (N = 30 or 60 rpm) over a wide range of impeller to tank diameter ratios from 0.53 to 0.98.Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) have been used to determine local velocity fields, shear rates, flow numbers and mixing times respectively, with impeller power number Po obtained from torque measurements. A down-pumping flow pattern is observed, with maximum normalised velocities of 25% of the impeller tip speed observed in the axial plane, increasing to 60% in the rotational plane due to solid body rotation. Angle resolved measurements found these to be slightly increased as the impeller passes the image plane, with viscoelastic fluids displaying a greater uniformity of velocity across the image planes due to elastic energy storage. Maximum shear rates are greatest between the impeller and the wall, yet remain low i.e. O (10) s -1 . Mixing times obtained from PLIF show that mixing times in viscoelastic fluids show a slight reduction compared to the Newtonian equivalent. The impeller power number was determined as Po = 0.6 in the turbulent regime, while the laminar constant K p and the Metzner-Otto constant k s were equal to 122 and 16.0 respectively. Highlights: "Butterfly" impellers used for processing of viscoelastic fluids. Low impeller Power number Po due to low blade area. Maximum shear rates of 17 s -1 in region between impeller and wall at N = 60 rpm. Mixing times longer in viscoelastic fluids due to elastic effects.

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Comparative study of different mixing strategies in small high throughput experimentation reactors

Cited by 37 publications

References 22 publications

Flow field and homogenization time assessment in continuously-fed stirred tanks

Flow field and homogenization time assessment in continuously-fed stirred tanks

Effect of shaft eccentricity on the laminar mixing performance of a radial impeller

Mixing of Newtonian and viscoelastic fluids using “butterfly” impellers

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