Theoretical prediction of gas–liquid mass transfer coefficient, specific area and hold-up in sparged stirred tanks

Garcı́a-Ochoa, Félix; Gómez, Eduardo Escalante

doi:10.1016/j.ces.2004.02.009

Cited by 160 publications

(126 citation statements)

References 40 publications

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“…This decrease of density and the formation of gas cavities lead to a decrease of the power input with respect to the power input into a pure liquid at the same agitation speed. [26][27][28][29] In other words, the gassed system needs higher agitation speed to have the same power input as the ungassed. Apart from the bump, the X H2;L2S shows the same trend as X H2;i2L , reaching a plateau.…”

Section: Separation Of Mass Transfer Resistancesmentioning

confidence: 99%

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Determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors

Stamatiou

Muller

2016

AIChE Journal

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A methodology for the determination of mass transfer resistances of fast reactions in three-phase mechanically agitated slurry reactors under the reaction conditions is presented. The mass transfer resistances affect significantly the overall mass transfer rate, the design equation and consequently the scale up of the reactor. There is not established methodology to separate the mass transfer resistances under reaction conditions by changing catalyst loading and manipulating the process variables, pressure and agitation speed. This allows to avoid the use of different catalyst particles and give the chance to calculate the mass transfer resistances without caring about the type of catalyst. We calculate each mass transfer resistance under conditions which do not allow to neglect any of the resistances. It is shown that the level off of mass transfer rate which is developed in the plot of mass transfer rate against agitation speed plots is not enough to determine the limiting regime. The hydrogenation of styrene over Pd/C (5% catalyst content) is used as case study to demonstrate the methodology.

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Section: Separation Of Mass Transfer Resistancesmentioning

confidence: 99%

“…We used the classical correlation based on the theory of isotropic turbulence using the power consumption per liquid volume and the superficial gas velocity to compare our experimental data. 27,[30][31][32][33][34][35] …”

Section: Correlationsmentioning

confidence: 99%

Determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors

Stamatiou

Muller

2016

AIChE Journal

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“…Non-coalescing liquids have surface tension reducing properties which, together with turbulence, determine the bubble di ameter [50] . As swface tension decreases, the turbulent forces provided by impeller agitation are able to decrease the bubble diameter.…”

Section: Surfactants and Anti-foaming Agentsmentioning

confidence: 99%

Mixing Considerations in Stirred Tank Bioreactors When Using Fluid Property Altering Microorganisms

Kadic

Heindel

2010

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C

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Stirred tank reactors are one of the standard reactors in the chemical industry and have been widely implemented for biological applications. They are used with viscous liquids, slurries, very low gas flow rates, and large liquid volumes. Stirred tank bioreactors are popular because a well-mixed state, required or preferred for numerous biological processes, is usually achieved in such situations; however, many production processes using microorganisms tend to experience fluid property alterations, which significantly impact mixing, operational parameters, and process results. The most troubling issues occur when a fluid gradually undergoes a viscosity change and/or slowly exhibits non-Newtonian behavior due to microorganism growth since these will alter the flow conditions and possibly limit the conversion rate or production scale. This paper provides an overview of the relevant mixing issues in stirred tank bioreactors when using a range of fluid viscosities, surface tensions, and/or non-Newtonian fluids. ABSTRACT Stirred tank reactors are one of the standard reactors in the chemical industry and have been widely implemented for biological applications. They are used with viscous liquids, lurries, very low gas flow rates, and large liquid vo lumes. tirred tank bioreactors are popular because a well-mixed state, required or prefetTed for numerous biological processes, is usually achieved in such situations; however, many production processes using microorganisms tend to experience fluid property alterations, which significantly impact mixing, operational parameters, and process results. The most troubling i ues occur when a fluid gradually undergoes a viscosity change and/or slowly exhibits non-Newtonian behavior due to microorganism growth since these will alter the flow conditions and possibly limit the conversion rate or production sca le. This paper provides an overview of the relevant mixing issues in tirred tank bioreactors when using a range of fluid viscosities, urface tensions, and/or non-Newtonian fluids .

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“…The effect of gas bubbles to the mass transfer coefficient is taken into account with the proportionality coefficient. The value of 0.301 for the coefficient, proposed by Kawase [18], has been tested by Garcia-Ochoa and Gomez [19] and was found to produce accurate results for gas-liquid mass transfer in stirred reactors.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study of Multiphase Mixing Hydrodynamics in Batch Stirred Tank Applied to Ammoniacal Thiosulphate Leaching of Gold

Gradov¹,

González²,

Vauhkonen³

et al. 2017

J Chem Eng Process Technol

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Hydrodynamics of aerated slurry is studied experimentally and numerically using the example of thiosulphate leaching of gold concentrate. The studied milled concentrate has shear-thinning fluid rheology and it was imitated by water-based solutions of CMC. Presence of electrolytes, as in the case of the leaching slurry, has great influence on bubble size distribution. Primary phase flow is measured by Particle Image Velocimetry. Local gas hold-up in aerated CMC 50000 (0.15 w%) solution is measured by Electrical Impedance Tomography. Volumetric mass transfer is measured by dynamic method in different CMC solutions over a range of operational conditions in absence and presence of electrolytes. The experimental data was used in CFD modelling of the aerated slurry. Single phase hydrodynamics of shear-thinning fluid (CMC 50000 (0.15 w%)) have been modelled and validated against experimental data with reasonable agreement. Multiphase mixing of the thiosulphate slurry was modelled with the assumption of constant bubble size. The results of the simulations and measurements are presented and discussed.

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Theoretical prediction of gas–liquid mass transfer coefficient, specific area and hold-up in sparged stirred tanks

Cited by 160 publications

References 40 publications

Determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors

Determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors

Mixing Considerations in Stirred Tank Bioreactors When Using Fluid Property Altering Microorganisms

Experimental and Numerical Study of Multiphase Mixing Hydrodynamics in Batch Stirred Tank Applied to Ammoniacal Thiosulphate Leaching of Gold

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