Correlating Gas-Liquid Mass Transfer in a Stirred-Tank Reactor

Kapic, Amir; Heindel, Theodore J.

doi:10.1205/cherd.05117

Cited by 52 publications

(73 citation statements)

References 12 publications

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“…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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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: 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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“…20, 21 For example, a correlation for O 2 -liquid mass transfer based on the energy input criteria of the form in eq 3 was shown to be flow-regimedependent and restricted to a single STR size. 8 Geometric similarity is usually satisfied in an STR scale-up analysis, and therefore, if eq 3 is used for an STR scale-up model, it should account for the hydrodynamic similarity between different reactor sizes. It is likely that the power density (P g /V L ) term alone is not enough to achieve gas-liquid hydrodynamic similarity in the STR flow patterns, and additional terms for scale-up are needed to account for required flow pattern similarity.…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that eq 7 is for dissolved CO, was obtained for a single vessel size (T ) 0.211 m), and is assumed to hold for other reactor sizes because the scale-up model (eq 5) was shown to be reliable in the ALC region for a wide range of STR sizes. 8 The superficial gas velocity (U g ) is an important variable in gas-liquid mass transport because it provides the actual amount of dispersed gas to the vessel. Yawalkar et al 25 and Kapic and Heindel 8 have shown that the dispersion parameter (N/N CD ) is reliable in achieving hydrodynamic similarity in different STR sizes.…”

Section: Resultsmentioning

confidence: 99%

Carbon Monoxide Mass Transfer in a Syngas Mixture

Kapic

Jones

Heindel

2006

Ind. Eng. Chem. Res.

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A myoglobin assay for measuring concentrations of dissolved carbon monoxide (CO) from an artificial synthesis gas blend (20% CO, 18% CO2, 52% N2, and 10% H2) was utilized to determine volumetric CO−water mass-transfer rates in a 0.211-m-diameter stirred-tank reactor (STR). The data are well correlated using the power density and superficial gas velocity, but this correlation is valid only for this STR size. A gas−liquid scale-up model developed for dissolved oxygen mass-transfer rates using air was used to develop a CO−liquid scale-up model for syngas fermentation. The model is applicable in the STR hydrodynamic range associated with after-large-cavity (ALC) formation and assumed to hold for other STR sizes. A myoglobin assay for measuring concentrations of dissolved carbon monoxide (CO) from an artificial synthesis gas blend (20% CO, 18% CO 2 , 52% N 2 , and 10% H 2 ) was utilized to determine volumetric CO-water masstransfer rates in a 0.211-m-diameter stirred-tank reactor (STR). The data are well correlated using the power density and superficial gas velocity, but this correlation is valid only for this STR size. A gas-liquid scaleup model developed for dissolved oxygen mass-transfer rates using air was used to develop a CO-liquid scale-up model for syngas fermentation. The model is applicable in the STR hydrodynamic range associated with after-large-cavity (ALC) formation and assumed to hold for other STR sizes.

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“…The values of KLa are affected by several features, including the geometry of the tank, type of impeller, agitation speed, aeration rate, media composition and properties [7]. The determination of the KLa in mixing is also crucial to baseline efficiency parameters and to quantify the optimum operating variables.…”

Section: Introductionmentioning

confidence: 99%

Study of gas–liquid mixing in stirred vessel using electrical resistance tomography

Sher

Sajid

Tokay

et al. 2016

Asia-Pacific J Chem Eng

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Hamad (2016) Study of gas-liquid mixing in stirred vessel using electrical resistance tomography. Asia-Pacific Journal of Chemical Engineering . ISSN 1932ISSN -2143 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/35359/1/Manuscript%20ERT.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractThis study presents a full operation and optimisation of a mixing unit; an innovative approach is developed to address the behaviour of gas-liquid mixing by using Electrical Resistance Tomography (ERT). The validity of the method is investigated by developing the tomographic images using different numbers of baffles in a mixing unit. This technique provided clear visual evidence of better mixing that took place inside the gasliquid system and the effect of a different number of baffles on mixing characteristics. For optimum gas flow rate (m 3 /s) and power input (kW), the oxygen absorption rate in water was measured. Dynamic gassingout method was applied for five different gas flow rates and four different power inputs to find out mass transfer coefficient (KLa). The rest of the experiments with one up to four baffles were carried out at these optimum values of power input (2.0 kW) and gas flow rate (8.5×10 -4 m 3 /s). The experimental results and tomography visualisations showed that the gasliquid mixing with standard baffling provided near the optimal process performance and good mechanical stability, as higher mass transfer rates were obtained using a greater number of baffles. 2 mixing was remarkably reduced in the case of four baffles as compared to without any baffle. The process economics study showed that the increased cost of baffles installation accounts for less cost of energy input for agitation. The process economics have also revealed that the optimum numbers of baffles are four in the present mixing unit and the use of an optimum number of baffles reduced the energy input cost by 54%.

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Correlating Gas-Liquid Mass Transfer in a Stirred-Tank Reactor

Cited by 52 publications

References 12 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

Carbon Monoxide Mass Transfer in a Syngas Mixture

Study of gas–liquid mixing in stirred vessel using electrical resistance tomography

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