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- Andersson, Nils Å. I., et al.
(författare)
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An in-Depth Model-Based Analysis of Decarburization in the AOD Process
- 2012
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 83:11, s. 1039-1052
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Tidskriftsartikel (refereegranskat)abstract
- A previously reported flow and reaction model for an argon-oxygen decarburization converter was extended to also include a thermodynamic description. An in-depth study of the model results has been conducted to answer how concentrations of elements and species in the converter at different locations change with time. This may contribute to the understanding of the mechanisms of the refining procedure in the argon-oxygen decarburization process. The refining procedure includes several step-wise changes of an injected gas composition to higher and higher inert gas ratio, called step changes. A step change leads to a decreased partial pressure of carbon monoxide and maintains the decarburization at a higher efficiency. The results shows early and late concentration profiles for the first injection step and suggests a way to determine when a step change should be made. Moreover, the step change could be determined by calculating the carbon concentration profiles and deciding when the carbon concentration gradients start to diminish.
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| 5. |
- Chen, Chao, et al.
(författare)
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A Model Study of Inclusions Deposition, Macroscopic Transport, and Dynamic Removal at Steel–Slag Interface for Different Tundish Designs
- 2016
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 47:3, s. 1916-1932
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents computational fluid dynamics (CFD) simulation results of inclusions macroscopic transport as well as dynamic removal in tundishes. A novel treatment was implemented using the deposition velocity calculated by a revised unified Eulerian deposition model to replace the widely used Stokes rising velocity in the boundary conditions for inclusions removal at the steel–slag interface in tundishes. In this study, the dynamic removal for different size groups of inclusions at different steel–slag interfaces (smooth or rough) with different absorption conditions at the interface (partially or fully absorbed) in two tundish designs was studied. The results showed that the dynamic removal ratios were higher for larger inclusions than for smaller inclusions. Besides, the dynamic removal ratio was higher for rough interfaces than for smooth interfaces. On the other hand, regarding the cases when inclusions are partially or fully absorbed at a smooth steel–slag interface, the removal ratio values are proportional to the absorption proportion of inclusions at the steel–slag interface. Furthermore, the removal of inclusions in two tundish designs, i.e., with and without a weir and a dam were compared. Specifically, the tundish with a weir and a dam exhibited a better performance with respect to the removal of bigger inclusions (radii of 5, 7, and 9 μm) than that of the case without weir and dam. That was found to be due to the strong paralleling flow near the middle part of the top surface. However, the tundish without weir and dam showed a higher removal ratio of smaller inclusions (radius of 1 μm). The reason could be the presence of a paralleling flow near the inlet zone, where the inclusions deposition velocities were much higher than in other parts.
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| 6. |
- Tilliander, Anders, et al.
(författare)
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A Three-Dimensional Three-Phase Model of Gas Injection in AOD Converters
- 2014
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:3, s. 376-387
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Tidskriftsartikel (refereegranskat)abstract
- A mathematical model of gas injection in the AOD converter process has been developed by augmentation of an earlier developed three-dimensional two-phase model to the slag phase and an industrial relevant geometry including six nozzles. The model is based on fundamental transport equations and includes separate solution of the steel and the gas phases and their coupling by friction as well as the slag phase. The 3D 3-phase (steel, slag, and gas) AOD model has been used to predict fluid flow, turbulence, and bubble characteristics as well as fluid-slag dispersion. In addition, two different gas flow rates have been simulated which resulted in quite different flow pattern. This new findings opens up for future investigations of gas-metal reactions in the AOD converter, which are of key interest from an industrial point of view.
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| 7. |
- Tilliander, Anders, et al.
(författare)
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Fundamental mathematical modeling of gas injection in AOD converters
- 2004
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Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 44:2, s. 326-333
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Tidskriftsartikel (refereegranskat)abstract
- A novel mathematical model of gas injection in the AOD converter process has been developed. The model is based on fundamental transport equations and includes separate solutions of both the steel and the gas phases and their coupling by friction. The inlet boundary conditions at the nozzle are predicted using a separate fundamental mathematical model of an AOD nozzle. This approach, together with the two phase solution, avoids the need to guess the inlet boundary conditions. The predicted gas plume has been compared to a plume from a scaled down water model of an AOD nozzle in a qualitative manner. The plume shapes are very similar, which indicates that the model predictions are of the right order of magnitude. The AOD model has also been used to predict fluid flow patterns, turbulence characteristics and bubble diameters.
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