Modelling of precipitation process by hybrid large eddy simulation - multizonal approach Application to uranium oxalate

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Submitted on 18 Dec 2019

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Modelling of precipitation process by hybrid large eddy simulation - multizonal approach Application to

uranium oxalate

M. Bertrand, E. Plasari, O. Lebaigue, . Lamarque N, F. Ducros, H. Muhr

To cite this version:

M. Bertrand, E. Plasari, O. Lebaigue, . Lamarque N, F. Ducros, et al.. Modelling of precipitation process by hybrid large eddy simulation - multizonal approach Application to uranium oxalate. SFGP 2017, Jul 2017, Nancy, France. SFGP 2017, 2017. �hal-02417727�

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Experimental study of the uranium IV oxalate precipitation : U(NO₃)₄ + 2 H₂C₂O₄ U(C₂O₄)₂.6H₂O + 4 HNO₃

Modelling of precipitation process by hybrid large eddy

simulation – multizonal approach

Application to uranium oxalate

Introduction

CFD modelling

Micromixing phenomena

Conclusion

 Precipitation process modelling : coupling of chemistry and hydrodynamics

 Different methodologies in the literature from hybrid methods based on multizonal models to a fully coupling in which the population balance equations are directly implemented into a CFD code

 Hybrid modelling : multizonal model that comprises several perfectly mixed compartments parameterised using CFD

Industrial precipitator reactor

OBJECTIVES

 Development of a multizonal approach with hydrodynamic information entirely extracted from LES

 Application to the simulation of the uranium oxalate precipitation performed in a vortex reactor



One-way coupling between the multizonal and LES models used to study in a quantitative way the influence of different operating parameters, allowing a better control of process or design



Hybrid approach allows both :



an accurate description of the flow field and relevant hydrodynamic data for the population balance resolution using LES,

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a flexible and efficient precipitation process modelling using multizonal model.

[1]. Lamarque N., B. Zoppé B., O. Lebaigue O., Y. Dolias Y., M. Bertrand M., F. Ducros F. Large-eddy simulation of the turbulent free-surface flow in an unbaffled stirred tank reactor. Chem Eng Sci 2010, 65:4307-4355.

[2] Bertrand M., D. Parmentier, Lebaigue O., Plasari E., Ducros F. Mixing study in an unbaffled stirred precipitator using LES modelling, International Journal of Chemical Engineering 2012, ID 450491.

[3] Bertrand M., Lamarque N., Lebaigue O., Plasari E., Ducros F. Micromixing characterisation in rapid mixing devices by chemical methods and LES modelling. Chemical Engineering Journal 2015, 283:462– 475.

[4] Bertrand M., Plasari E., Lebaigue O., Baron P., Lamarque N, Ducros F. Hybrid LES–multizonal modelling of the uranium oxalate precipitation. Chemical Engineering Science 2012, 77:95–104.

Which micromixing time with LES simulation ?

=> Two models developed [3], based on the classical Eddy Dissipation Concept of Magnussen and Hjertager :

 LES variance model

 LES diffusive model

Precipitation modelling

Murielle BERTRAND1_{*, Edouard PLASARI}2_{, Olivier LEBAIGUE}3_{, Nicolas LAMARQUE}4_{, Frédéric DUCROS}3_{, Hervé MUHR}2

1- CEA, Nuclear Energy Division, Research Department on Mining and Fuel Recycling Processes BP 17171 F-30207 Bagnols-sur-Cèze, France 2- Reaction and Process Engineering Laboratory, University of Lorraine, Nancy, France

3- CEA, Grenoble, France

4- European centre for research and advanced training in scientific computation researches, Toulouse, France

Vortex reactor:

 Operating in the fuel reprocessing industry

 Unbaffled cylindrical glass vessel

 Stirred by a cylindrical magnetic rod

LES Modelling

[1]

:

 CFD code : Trio_U developed at CEA www-trio-u.cea.fr

 Using the Large Eddy Simulation approach

 Homogeneous unstructured grid with about 650,000

tetrahedral elements

 Free surface : Discontinuous Front Tracking method

 Magnetic rod :Immersed Boundary Condition model

 Under-grid model : WALE

L₄₃ ~ 8 µm

L₄₃ ~ 0.9 µm

Reagent injection into the free vortex _{Reagent injection into the forced vortex} feeding

Numerical simulation - Fluid particle follow-up Numerical simulation - Fluid particle follow-up

 Crystallite properties : feeding feeding feeding  Crystallite properties :

Results

[2]

:

 In agreement with Nagata's model => rotation of the fluid around the vessel symmetry axis

 Variation of the tangential velocity module in space and time with the rod position

 Good agreement with theoretical aspects and

experimental measurements performed by Laser Doppler Velocimetry t t R Sc Sc       2 1 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 0 20 40 60 80 100 120 rayon [m m ] U  [ m /s ] z=180mm Théta=0° z=180mm Théta=180° z=180mm Theta=180° expe z=180mm Theta=0° expe

Population balance and turbulence

[4]

Classical approach in chemical engineering science Fully coupling Hybrid methods Concentration fields CFD - LES Flow fields CFD - LES

Population balance resolution Multizonal model

Blue : simulation Red : experimental

Radius (mm)

Turbulence structure Comparison experiments / modelling