CFD Prediction of Gas-Liquid Flow in an Aerated Stirred Vessel Using the Population Balance Model

• Authors: Zbyněk Kálal , Milan Jahoda , Ivan Fořt
• Languages of publication: EN

Abstracts

EN

The main topic of this study is the experimental measurement and mathematical modelling of global gas hold-up and bubble size distribution in an aerated stirred vessel using the population balance method. The air-water system consisted of a mixing tank of diameter T = 0.29 m, which was equipped with a six-bladed Rushton turbine. Calculations were performed with CFD software CFX 14.5. Turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the homogeneous MUSIG method with 24 bubble size groups. To achieve a better prediction of the turbulent quantities, simulations were performed with much finer meshes than those that have been adopted so far for bubble size distribution modelling. Several different drag coefficient correlations were implemented in the solver, and their influence on the results was studied. Turbulent drag correction to reduce the bubble slip velocity proved to be essential to achieve agreement of the simulated gas distribution with experiments. To model the disintegration of bubbles, the widely adopted breakup model by Luo & Svendsen was used. However, its applicability was questioned.

Keywords

EN

CFD; mixing tank; gas-liquid; drag correction; bubble size distribution

• Publisher: De Gruyter Open
• Journal: Chemical and Process Engineering
• Year: 2014
• Volume: 35
• Issue: 1
• Pages: 55-73

Dates

published

1 - 3 - 2014

accepted

16 - 1 - 2014

online

25 - 4 - 2014

received

29 - 10 - 2013

Contributors

author

Zbyněk Kálal

• Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic

author

Milan Jahoda

• Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic

author

Ivan Fořt

• Czech Technical University in Prague, Technická 4, 166 07 Prague 6, Czech Republic

References

• Ahmed S.U., Ranganathan P., Pandey A., Sivaraman S., 2010. Computational fluid dynamics modeling of gas dispersion in multi impeller bioreactor. J. Biosci. Bioeng., 109, 588-597. DOI: 10.1016/j.jbiosc.2009.11.014.[WoS][Crossref]
• Alopaeus V., Koskinen J., Keskinen K. I., 1999. Simulation of the population balances for liquid-liquid systems in a nonideal stirred tank. Part 1 - Description and qualitative validation of the model. Chem. Eng. Sci., 54, 5887-5899. DOI: 10.1016/S0009-2509(99)00170-0.[Crossref]
• Alopaeus V., Koskinen J., Keskinen K. I., Majander J., 2002. Simulation of the population balances for liquidliquid systems in a nonideal stirred tank. Part 2 - parameter fitting and the use of the multiblock model for dense dispersions. Chem. Eng. Sci., 57, 1815-1825. DOI: 10.1016/S0009-2509(02)00067-2.[Crossref]
• ANSYS, Inc., 2012. CFX-Solver Theory Guide, Release 14.5. Canonsburg, PA, USA.
• Aubin J., Fletcher D. F., Xuereb C., 2004. Modeling turbulent flow in stirred tanks with CFD: the influence of the modeling approach, turbulence model and numerical scheme. Exp. Therm. Fluid Sci., 28, 431-445. DOI: 10.1016/j.expthermflusci.2003.04.001.[Crossref]
• Bakker A., van den Akker H.E.A., 1994. A computational model for the gas-liquid flow in stirred reactors. Chem. Eng. Res. Des., 72, 594-606.
• Brucato A., Grisafi F., Montante G., 1998. Particle drag coefficients in turbulent fluids. Chem. Eng. Sci., 53, 3295-3314. DOI: 10.1016/S0009-2509(98)00114-6.[Crossref]
• Coroneo M., Montante G., Paglianti A., Magelli F., 2011. CFD prediction of fluid flow and mixing in stirred tanks: Numerical issues about the RANS simulations. Comput. Chem. Eng., 35, 1959-1968. DOI: 10.1016/j.compchemeng.2010.12.007.[WoS][Crossref]
• Cui Y.Q., van der Lans R.G.J.M., Luyben K.C.A.M., 1996. Local power uptake in gas-liquid systems with single and multiple Rushton turbines. Chem. Eng. Sci., 51, 2631-2636. DOI: 10.1016/0009-2509(96)00128-5.[Crossref]
• Deglon D.A., Meyer C. J., 2006. CFD modelling of stirred tanks: Numerical considerations. Miner. Eng., 19, 1059-1068. DOI: 10.1016/j.mineng.2006.04.001.[Crossref]
• Frank T., Zwart P.J., Krepper E., Prasser H.-M., Lucas D., 2008. Validation of CFD models for mono- and polydisperse air-water two-phase flows in pipes. Nucl. Eng. Des., 238, 647-659. DOI: 10.1016/j.nucengdes.2007.02.056.[WoS][Crossref]
• Geary N. W., Rice R. G., 1991. Bubble size prediction for rigid and flexible spargers. AIChE J., 37, 161-168. DOI: 10.1002/aic.690370202.[Crossref]
• Hagesaether L., Jakobsen H. A., Svendsen H. F., 2002. A model for turbulent binary breakup of dispersed fluid particles. Chem. Eng. Sci., 57, 3251-3267. DOI: 10.1016/S0009-2509(02)00197-5.[Crossref]
• Ishii M., Zuber N., 1979. Drag coefficient and relative velocity in bubbly, droplet or particulate flows. AIChE J., 25, 843-855. DOI: 10.1002/aic.690250513.[Crossref]
• Kerdouss F., Bannari A., Proulx P., Bannari R., Skrga M., Labrecque Y., 2008. Two-phase mass transfer coefficient prediction in stirred vessel with a CFD model. Comput. Chem. Eng., 32, 1943-1955. DOI: 10.1016/j.compchemeng.2007.10.010.[WoS][Crossref]
• Khopkar A. R., Rammohan A. R., Ranade V.V., Dudukovic M. P., 2005. Gas-liquid flow generated by a Rushton turbine in stirred vessel: CARPT/CT measurements and CFD simulations. Chem. Eng. Sci., 60, 2215-2229. DOI: 10.1016/j.ces.2004.11.044.[Crossref]
• Kumar S., Ramkrishna D., 1996. On the solution of population balance equations by discretization - I. A fixed pivot technique. Chem. Eng. Sci., 51, 1311-1332. DOI: 10.1016/0009-2509(96)88489-2.[Crossref]
• Laakkonen M., Moilanen P., Alopaeus V., Aittamaa J., 2007. Modelling local bubble size distributions in agitated vessels. Chem. Eng. Sci., 62, 721-740. DOI: 10.1016/j.ces.2006.10.006.[Crossref][WoS]
• Lehr F., Millies M., Mewes D., 2002. Bubble-size distributions and flow fields in bubble columns. AIChE J., 48, 2426-2443. DOI: 10.1002/aic.690481103.[Crossref]
• Liao Y., Lucas D., 2010. A literature review on mechanisms and models for the coalescence process of fluid particles. Chem. Eng. Sci., 65, 2851-2864. DOI: 10.1016/j.ces.2010.02.020.[Crossref][WoS]
• Lo S., 1996. Application of the MUSIG model to bubbly flows. AEAT-1096, AEA Technology.
• Luo H., Svendsen H.F., 1996. Theoretical model for drop and bubble breakup in turbulent dispersions. AIChE J., 42, 1225-1233. DOI: 10.1002/aic.690420505.[Crossref]
• Marchisio D.L., Fox R.O., 2013. Computational models for polydisperse particulate and multiphase systems. Cambridge University Press, New York, USA.
• Martínez-Bazán C., Montanes J.L., Lasheras J.C., 1999. On the breakup of an air bubble injected into fully developed turbulent flow. Part 1. Breakup frequency. J. Fluid Mech., 401, 157-182. DOI: 10.1017/S0022112099006680.[Crossref]
• Montante G., Horn D., Paglianti A., 2008. Gas-liquid flow and bubble size distribution in stirred tanks. Chem. Eng. Sci., 63, 2107-2118. DOI: 10.1016/j.ces.2008.01.005.[Crossref]
• Montante G., Paglianti A., Magelli F., 2007. Experimental analysis and computational modelling of gas-liquid stirred vessels. Chem. Eng. Res. Des., 85, 647-653. DOI: 10.1205/cherd06141.[Crossref]
• Petitti M., Nasuti A., Marchisio D.L., Vanni M., Baldi G., Mancini N., Podenzani F., 2010. Bubble size distribution modeling in stirred gas-liquid reactors with QMOM augmented by a new correction algorithm. AIChE J., 56, 36-53. DOI: 10.1002/aic.12003.[WoS][Crossref]
• Prince M.J., Blanch H.W., 1990. Bubble coalescence and break-up in air-sparged bubble columns. AIChE J., 36, 1485-1499. DOI: 10.1002/aic.690361004.[Crossref]
• Rakoczy R., Masiuk S., 2009. Experimental study of bubble size distribution in a liquid column exposed to a rotating magnetic field. Chem. Eng. Process., 48, 1229-1240. DOI: 10.1016/j.cep.2009.05.001.[WoS][Crossref]
• Ranganathan P., Sivaraman S., 2011. Investigations on hydrodynamics and mass transfer in gas-liquid stirred reactor using computational fluid dynamics. Chem. Eng. Sci., 66, 3108-3124. DOI: 10.1016/j.ces.2011.03.007.[Crossref][WoS]
• Rutherford K., Mahmoudi S.M.S., Lee K.C., Yianneskis M., 1996. The influence of Rushton impeller blade and disk thickness on the mixing characteristics of stirred vessels. Chem. Eng. Res. Des., 74, 369-378.
• Sato Y., Sekoguchi K., 1975. Liquid velocity distribution in two-phase bubble flow. Int. J. Multiphase Flow, 2, 79-95. DOI: 10.1016/0301-9322(75)90030-0.[Crossref]
• Scargiali F., D'Orazio A., Grisafi F., Brucato A., 2007. Modelling and simulation of gas-liquid hydrodynamics in mechanically stirred tanks. Chem. Eng. Res. Des., 85, 637-646. DOI: 10.1205/cherd06243.[Crossref][WoS]
• Schiller L., Naumann Z., 1935. A drag coefficient correlation. Z. Ver. Deutscher Ing., 77, 318.
• Selma B., Bannari R., Proulx P., 2010. Simulation of bubbly flows: Comparison between direct quadrature method of moments (DQMOM) and method of classes (CM). Chem. Eng. Sci., 65, 1925-1941. DOI: 10.1016/j.ces.2009.11.018.[Crossref]
• Tomiyama A., Kataoka I., Zun I., Sakaguchi T., 1998. Drag coefficients of single bubbles under normal and microgravity conditions. JSME Int. J. Series B, 41, 472-479. DOI: 10.1299/jsmeb.41.472. van't Riet K., 1975. Turbine agitator hydrodynamics and dispersion performance. Ph.D. thesis, University of Delft, The Netherlands.[Crossref]
• Wang T., Wang J., Jin Y., 2003. A novel theoretical breakup kernel function for bubbles/droplets in a turbulent flow. Chem. Eng. Sci., 58, 4629-4637. DOI: 10.1016/j.ces.2003.07.009. [Crossref]

Identifiers

DOI

10.2478/cpe-2014-0005