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  • 1.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Kennedy, M. W.
    Aune, R. E.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Analysis on Experimental Investigation and Mathematical Modelling of Incompressible Flow through Ceramic Foam FiltersManuscript (preprint) (Other academic)
  • 2.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Saffari Pour, Mohsen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Significance of Fluid Bypassing Effect on Darcy and Non-Darcy Permeability Parameters of Ceramic Foam FiltersManuscript (preprint) (Other academic)
  • 3.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Saffari Pour, Mohsen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pӓr Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters2017In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 1, p. 197-207Article in journal (Refereed)
    Abstract [en]

    Ceramic foam filters (CFFs) are used to remove solid particles and inclusions from molten metal. In general, molten metal which is poured on the top of a CFF needs to reach a certain height to build the required pressure (metal head) to prime the filter. To estimate the required metal head, it is necessary to obtain permeability coefficients using permeametry experiments. It has been mentioned in the literature that to avoid fluid bypassing, during permeametry, samples need to be sealed. However, the effect of fluid bypassing on the experimentally obtained pressure gradients seems not to be explored. Therefore, in this research, the focus was on studying the effect of fluid bypassing on the experimentally obtained pressure gradients as well as the empirically obtained Darcy and non-Darcy permeability coefficients. Specifically, the aim of the research was to investigate the effect of fluid bypassing on the liquid permeability of 30, 50, and 80 pores per inch (PPI) commercial alumina CFFs. In addition, the experimental data were compared to the numerically modeled findings. Both studies showed that no sealing results in extremely poor estimates of the pressure gradients and Darcy and non-Darcy permeability coefficients for all studied filters. The average deviations between the pressure gradients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 57.2, 56.8, and 61.3 pct. The deviations between the Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples found to be 9, 20, and 31 pct. The deviations between the non-Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 59, 58, and 63 pct.

  • 4.
    Alexis, Jonas
    et al.
    Swerea-Mefos.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, Superseded Departments, Applied Process Metallurgy.
    Heat and fluid-flow models for stirring conditionsin ladle furnaces and their practical implications in secondary refiningoperations1997In: Clean Steel 5, Vol 1,  2-4 June 1997, Balatonszeplak,Hungary, Balatonszeplak, 1997, p. 49-58Conference paper (Refereed)
  • 5.
    Alexis, Jonas
    et al.
    Swerea-Mefos.
    Jönsson, Pär
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    A model of an induction-stirred ladle accounting for slag and surface deformation1999In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 39, no 8, p. 772-778Article in journal (Refereed)
  • 6.
    Alexis, Jonas
    et al.
    Swerea-Mefos.
    Jönsson, Pär
    KTH, Superseded Departments, Metallurgy.
    Jonsson, Lage
    Heating and electromagnetic stirring in a ladle furnace – a simulationmodel2000In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 40, no 11, p. 1098-1104Article in journal (Refereed)
    Abstract [en]

    A three-dimensional simulation model coupling heating and induction stirring in an ASEA-SKF ladle furnace was developed. Data of the heat transfer from the area to the steel bath were predicted in a separate model and included as boundary conditions in a ladle model. The are model considers the contributions of heat transferred by of each of the following mechanisms: radiation, convection, condensation and energy transported by electrons. Predictions were made to simulate the change of temperature distribution in the ladle during simultaneous heating with electrodes and stirring by induction. A first attempt was made to compare the predictions with measured temperatures from a 100 t ASEA-SKF ladle. The agreement was found to be fairly good when heat-flux data for a 25 cm are length were used as input to the ladle model. This indicates that the model can be used for more in-depth studies of the effects of heating for ladles that are inductively stirred.

  • 7. Andersson, A. M. T.
    et al.
    Jonsson, Lage T. I.
    KTH, Superseded Departments, Materials Science and Engineering.
    Jonsson, P. G.
    A model of reoxidation from the top slag and the effect on sulphur refining during vacuum degassing2003In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 32, no 3, p. 123-136Article in journal (Refereed)
    Abstract [en]

    A 2-dimensional fluid-flow model covering 3 phases (steel, slag and gas) has been augmented to include thermodynamic equations to study simultaneous reoxidation and desulphurization, including macro kinetic behaviour. The numerical simulations were isothermal. Predicted steel and slag component concentrations were compared with plant data from vacuum degassing and the agreement was found to be quite good. When the initial FeO content in the slag was increased, the predicted desulphurization rate decreased, the final sulphur content in the steel increased, and aluminium loss increased. When the temperature was increased, the predicted aluminium loss decreased somewhat. The effect of changes in temperature on the predicted final sulphur content was influenced by the initial FeO content in the top slag. The results show that the model can be used for future work on the dynamic modelling of slag/metal reactions if the initial FeO content is less than 3-4% (by weight).

  • 8.
    Andersson, Margareta A. T.
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Jonsson, Lage T. I.
    KTH, Superseded Departments, Materials Science and Engineering.
    Jonsson, P. G.
    A thermodynamic and kinetic model of reoxidation and desulphurisation in the ladle furnace2000In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 40, no 11, p. 1080-1088Article in journal (Refereed)
    Abstract [en]

    A thermodynamic and kinetic model of reoxidation and desulphurisation in the ladle furnace has been developed by using a two-dimensional fluid-flow model combined with equations expressing the thermodynamics of reoxidation and desulphurisation. More specifically ladle vacuum treatment of a gas-stirred ladle has been simulated. In order to describe the activities of the oxide components of the slag, expressions by Ohta and Suito(1)) were adopted. The thermodynamic model describes the slag/metal equilibria between Al, Si, O, Mn and S in the molten steel and Al2O3, SiO2, FeO, MnO and S in the slag. A fluid dynamic model that considers the slag, steel and argon phases derives the kinetics. Results from an isothermal calculation have been heuristically compared with industrial plant data and they show good agreement. The model results have also revealed that the reduction of silica plays a part in aluminium loss during ladle treatment.

  • 9.
    Andersson, Margareta
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Appelberg, Jesper
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Shibata, Hiroyuki
    Tohoku University, Institute of Multidisciplinary Research for Advanced Materials.
    Kitamura, Shinya
    Tohoku University, Institute of Multidisciplinary Research for Advanced Materials.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Some Aspects on Grain Refining Additions with Focus on Clogging during Casting2006In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 46, no 6, p. 814-823Article in journal (Refereed)
    Abstract [en]

    Some ideas of how to study optimum conditions for implementation of grain refining in liquid steel processing with focus on how to avoid clogging are discussed. It is assumed that the inclusions most beneficial for grain refining are known from studies by physical metallurgists. The challenge for a process metallurgist is how to provide a homogeneous distribution of grain refiners at the onset of solidification. Four different ways of providing information to succeed with this are discussed. Thermodynamic modeling can be used to predict what additions to make to create potential grain refiners, if relevant thermodynamic data is available. Mathematical fluid-flow modeling can be used to study where to add potential grain refiners. It is discussed that the tundish is the most appropriate reactor to add grain refiners, since enough time is given to a complete mixing of the grain refiner into the steel before the steel enters the mold. By using the scanning laser microscopy technique it is possible to study which potential grain refiners has the lowest attraction forces between each other. This is important in order to minimise growth of inclusions when they collide during transport in the tundish, which can lead to the formation of larger inclusions that do not serve as useful grain refiners. Finally, it is suggested that laboratory experiments are carried out in order to study the tendency for nozzle clogging, before the use of grain refiners is tested in industrial scale.

  • 10.
    Andersson, Margareta A.T.
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Hallberg, Malin
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Slag-metal reactions during ladle treatment with focus on desulphurisation2002In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 29, no 3, p. 224-232Article in journal (Refereed)
    Abstract [en]

    Within several cooperative projects, KTH (Royal Institute of Technology), Ovako Steel AB, and MEFOS have investigated the desulphurisation of bearing steel during vacuum degassing. The work includes thermodynamic calculations of the slag-metal equilibrium, CFD modelling of slag-metal reactions, and plant trials. Results from the various studies are presented and discussed in this paper. Models for predicting slag properties (sulphide capacity, viscosity, and oxide activities) in liquid slags as functions of slag composition and temperature have been used for the calculation of data which have been employed in static and dynamic modelling of sulphur refining. The results from static modelling show that the method allows fast and easy evaluation of the theoretical desulphurisation conditions during degassing at Ovako Steel AB, as well as theoretical determination of the parameters that have the greatest influence on the equilibrium sulphur distribution. The conclusion from dynamic modelling is that the vacuum degassing operation can be described dynamically with the present knowledge of sulphide capacity, sulphur distribution, viscosity, and oxide activities of ladle slags if this knowledge is combined with fluid flow modelling to derive the overall kinetics. The presented model approaches have been found useful in understanding the sulphur refining process at Ovako Steel AB. The dynamic modelling concept is also believed to have potential for dynamic descriptions of other slag-metal reactions in steelmaking.

  • 11.
    Andersson, Margareta
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Hallberg, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, Superseded Departments, Applied Process Metallurgy.
    Slag/metal reactionsduring ladle treatment with focus on desulphurisation2000In: 6thInternational Conference on Molten Slags, Fluxes and Salts, 2000Conference paper (Refereed)
  • 12.
    Andersson, Nils
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Fundamental decarburisation model of AOD process2013In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 40, no 5, p. 390-397Article in journal (Refereed)
    Abstract [en]

    A mathematical fluid flow model of gas injection in an argon–oxygen decarburisation (AOD) converter process has been coupled with a high temperature thermodynamic model. The current model is a further enhancement of an earlier developed three-dimensional, three-phase model, to also include some thermodynamics of the process. The model is based on fundamental transport equations and includes separate solutions for the steel, slag and the gas phases and their coupling by friction. The AOD model has been used to predict the first injection stage of decarburisation in an AOD converter. The predictions have been found to agree well with the corresponding results from an industrial process control model. One of the important observations from the simulations was that large concentration gradients of carbon exist in the AOD at an early stage and as the first injection step approaching its end the carbon gradients diminish. Also, the results show, in accordance with theory, that the local decarburisation rate is decreased at elevated pressures.

  • 13.
    Andersson, Nils
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Investigating the effectof slag on decarburization in an AOD converter using a fundamental model2013In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 84, no 2, p. 169-177Article in journal (Refereed)
    Abstract [en]

    A high-temperature thermodynamics model has been coupled with a fundamental mathematical model describing the fluid flow, where boundary conditions were chosen based on data for an industrial AOD converter. Using this model, the effect of both slag phases (a liquid part and a solid part) on the decarburization was studied. More specifically, the separation of chromium oxide to liquid slag as well as the effect of the amount of rigid top slag (solid)on the decarburization was investigated. The liquid slag was considered with respect to the uptake of chromium oxide, while the rigid top slag was only considered with respect to the increase of the metallostatic pressure in the steel melt. The results suggest that separation of chromium oxide to liquid slag results in a decreased decarburization rate. The same conclusion can be drawn with respect to the amount of solid top slag.

  • 14.
    Andersson, Nils
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Preliminary investigation of influence of temperature on decarburisation using fundamental AOD model2013In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 40, no 7, p. 551-558Article in journal (Refereed)
    Abstract [en]

    A high temperature thermodynamics model was earlier coupled with a fundamental mathematical model describing the fluid flow in an argon–oxygen decarburisation (AOD) converter and was initially validated for an idealised temperature description. More specifically, a linear average temperature relation was used such that the temperature would be isolated from other effects such as reactions and mixing. Thereafter, the effect of the starting temperature on the decarburisation was studied. The purpose is to provide some initial knowledge about how temperature affects the decarburisation in an AOD converter. The results suggest that the thermodynamic limit for carbon concentration after reaching the carbon removal efficiency (CRE) maxima is vertically translated downwards at higher temperatures. Furthermore, when plotting the mass ratio between CO and CO2, there is an indication of a point that may relate to a CRE maximum.

  • 15.
    Andersson, Nils Å. I.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A fundamental decarburization model of the AOD processIn: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812Article in journal (Other academic)
  • 16.
    Andersson, Nils Å. I.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    An in-Depth Model-Based Analysis of Decarburization in the AOD Process2012In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 83, no 11, p. 1039-1052Article in journal (Refereed)
    Abstract [en]

    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.

  • 17.
    Andersson, Nils Å. I.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Investigating the effect of slag on decarburization in an AOD coverter using a fundamental modelIn: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Other academic)
  • 18.
    Andersson, Nils Å. I.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Preliminary investigation of temperatur dependencies on decarburization in a fundamental AOD modelIn: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812Article in journal (Other academic)
  • 19.
    Beskow, Kristina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Viswanathan, N. N.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Sichen, Du
    KTH, Superseded Departments, Materials Science and Engineering.
    Study of the deoxidation of steel with aluminum wire injection in a gas-stirred ladle2001In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 32, no 2, p. 319-328Article in journal (Refereed)
    Abstract [en]

    In the present work, the deoxidation of liquid steel with aluminum wire injection in a gas-stirred ladle was studied by mathematical modeling using a computational fluid dynamics (CFD) approach. This was complemented by an industrial trial study conducted at Uddeholm Tooling AB (Hagfors, Sweden). The results of the industrial trials were found to be in accordance with the results of the model calculation. In order to study the aspect of nucleation of alumina, emphasis was given to the initial period of deoxidation, when aluminum wire was injected into the bath. The concentration distributions of aluminum and oxygen were calculated both by considering and not considering the chemical reaction. Both calculations revealed that the driving force for the nucleation of Al2O3 was very high in the region near the upper surface of the bath and close to the wire injection. The estimated nucleation rate in the vicinity of the aluminum wire injection point was much higher than the recommended value for spontaneously homogeneous nucleation, 10(3) nuclei/(cm(3)/s). The results of the model calculation also showed that the alumina nuclei generated at the vicinity of the wire injection point are transported to other regions by the flow.

  • 20. Burman, J.
    et al.
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security, Umeå, Sweden.
    Synthetic boundary conditions using les for urban dispersion modelling2017In: HARMO 2017 - 18th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, Proceedings, Hungarian Meteorological Service , 2017, p. 788-792Conference paper (Refereed)
    Abstract [en]

    Large Eddy Simulation with two sub-grid-scale models are used to simulate gas dispersion, utilizing alternatively constant values and synthetic turbulence at inflow boundaries. The results are compared with data from the JU2003 Atmospheric Dispersion Study in Oklahoma City. Turbulence statistics of the simulation is presented at two probe locations, one inside the city-core and one outside. In addition, comparisons with the measured concentration-data and maximum-values are conducted. It was found that in the core of the city, modeled turbulence is mainly determined by buildings and their configurations, and is only weakly affected by model type and assumed turbulence at inflow boundaries. Within the predicted flow-path, the tested models produce similar predictions of maximum concentration values, which in turn are similar to the experimental data. The results indicate that synthetic turbulence at the inflow boundary is less important when building generated turbulence dominate but it is important if not a local boundary layer is developed.

  • 21. Burman, Jan
    et al.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Issues when linking computational fluid dynamics for urban modeling to toxic load models: The need for further research2015In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 104, p. 112-124Article in journal (Refereed)
    Abstract [en]

    In order to predict casualties caused by chemical hazards in densely populated areas, state-of-the-art Computational Fluid Dynamic (CFD) techniques could be utilized together with toxic load models. In the current study, simulations of consequences of hypothetical releases of toxic gas in a city center are presented and discussed. CFD models that reproduce flow statistics would be most appropriate for this purpose since it could be expected that they will more realistically represent the environment. However, since concentration-peaks in the ever-present spatiotemporal fluctuations of airborne chemicals contribute so much to the toxic load, it is shown that straight-forward direct linking of a CFD model to a toxic load model is not a suitable approach for predicting consequences of a toxic release. Furthermore, it is demonstrated that the use of different turbulence models leads to different casualty assessments. Obviously, there is an urgent need to establish widely accepted methods, ideally with known uncertainty measures. Thus, further research in this area is of great importance.

  • 22.
    Burman, Jan
    et al.
    Swedish Def Res Agcy, FOI, Div CBRN Def & Secur, S-90182 Umea, Sweden.;Uppsala Univ, Dept Earth Sci, Uppsala, Sweden..
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Swedish Def Res Agcy.
    Rutgersson, Anna
    Uppsala Univ, Dept Earth Sci, Uppsala, Sweden..
    On possibilities to estimate local concentration variations with CFD-LES in real urban environments2019In: Environmental Fluid Mechanics, ISSN 1567-7419, E-ISSN 1573-1510, Vol. 19, no 3, p. 719-750Article in journal (Refereed)
    Abstract [en]

    Applied studies with Large Eddy Simulation (LES) of hazardous gas dispersion around buildings in cities have become increasingly feasible due to rapid advancements in computing technology. However, there is little extant literature investigating how each model's results compare with others, as well as their ability to predict near-field dispersion in a real city. In this study, three typical LES sub-grid-scale models are used to simulate gas dispersion, utilizing alternatively constant values and synthetic turbulence at inflow boundaries. The results are compared with data from the Joint Urban 2003 Atmospheric Dispersion Study in Oklahoma City. Flow and turbulence statistics of the simulation is presented at two probe locations, one inside the city-core and one outside. In addition, comparisons with the measured mean concentration and maximum concentration values are conducted. It was found that in the core of the city, simulated turbulence is mainly determined by buildings and their configurations, and is only weakly affected by model type and assumed turbulence at the inflow boundaries. On the other hand, outside and upwind the city center the turbulence set at the inflow boundaries is very important if realistic turbulence statistics is to be achieved. Downstream of the source, all tested models produce similar predictions of maximum concentration values, which in turn are similar to the experimental data. Thus, the results indicate that it could be better to use the LES calculated maximum-concentration instead of the calculated mean-concentration when developing methods for hazard area estimation.

  • 23.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A CFD Model Study of the Macroscopic Transport and Dynamic Removal of Inclusions at a Steel-Slag Interface for Different Tundish DesignsManuscript (preprint) (Other academic)
  • 24.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A Mathematical Modeling Study of the Influence of Small Amounts of KCl Solution Tracers on Mixing in Water and its Residence Time Distribution in a Continuous Flow Reactor-Metallurgical Tundish2015In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 137, p. 914-937Article in journal (Other academic)
    Abstract [en]

    In an earlier research (Chen et al., 2015a) a mathematical model was established to simulate tracer mixing (a KCl solution). The predicted Residence Time Distribution (RTD) curves showed good agreements with experimental RID curves for larger amounts of tracer additions. However, for smaller additions (50 mL) of a KCl solution into water, the predicted RID curves tended to deviate from the experimental RTD curves for a tundish (a continuous flow reactor). The current paper focuses on the possibilities that the predictability for smaller additions could be resolved by using a suitable turbulence model. The performance of five different turbulence models representing different modeling techniques and levels of complexity were tested in combination with using a density-coupled mixed composition fluid model to simulate the mixing, i.e. the following models: LVEL, Chen-Kim k-epsilon, MMK k-epsilon, Explicit Algebraic Reynolds Stress Model (EARSM), and Large Eddy Simulation (LES): Wall-Adapting Local Eddy-viscosity (WALE). The results indicate that models that tend to resolve turbulence structures renders better predictions of the mixing process of smaller tracer amounts. In addition, the influence of different tracer amounts on the flow in tundish was assessed. The simulation results for 75 mL, 100 mL, 150 mL, and 250 mL KCl tracer additions were compared. The results showed that in an upward flow the tracer will, sooner or later (dependent on the tracer amount), sink to the bottom. This is due to the higher density of the tracer compared to the density of water. From a physical modeling perspective, this issue is like the "butterfly effect". It is showed that for a slight increase of the amount of tracer, the flow field might be disturbed. This, in turn, will result in a shifted RTD curve.

  • 25.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, China .
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. Swedish Def Res Agcy, FOI, Div CBRN Def & Secur, Sweden.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A Mathematical Modeling Study of Tracer Mixing in a Continuous Casting Tundish2015In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 46, no 1, p. 169-190Article in journal (Refereed)
    Abstract [en]

    A mathematical model based on a water model was developed to study the tracer mixing in a single strand tundish. The mixing behavior of black ink and KCl solution was simulated by a mixed composition fluid model, and the data were validated by water modeling results. In addition, a model that solves the scalar transport equation (STE) without any physical properties of the tracer was studied and the results were compared to predictions using the density-coupled model. Furthermore, the mixing behaviors of different amounts of KCl tracers were investigated. Before the model was established, KCl tracer properties such as the KCl molecule diffusion (KMD), the water molecule self-diffusion (WSD) in KCl solution, and the KCl solution viscosity (KV) were evaluated. The RTD curve of 250 mL KCl for the KMD case was closer to the water modeling results than that of the case implemented with only density. Moreover, the ensemble average deviation of the RTD curves of the cases implemented with KMD+ WSD, KMD+ KV, and KMD+ WSD+ KV to the KMD case is less than 0.7 pct. Thus, the water self-diffusion and KV were neglected, while the KCl density and KMD were implemented in the current study. The flow pattern of black ink was similar to the STE result i. e., the fluid flowed upwards toward the top surface and formed a large circulating flow at the outlet nozzle. The flow behavior of the 100, 150, and 250 mL KCl cases exhibited a strong tendency to sink to the tundish bottom, and subsequently flow through the holes in the dam. Thereafter, it propagated toward the outlet nozzle. Regarding the KCl tracer amount, the tracer concentration propagated to the outlet nozzle much faster for the larger amount case than for the smaller amount cases. However, the flow pattern for the 50 mL KCl case was somewhat different. The fluid propagated to the top surface which acted like black ink during the initial injection, and subsequently the fluid flowed throughout the holes at a much slower pace. The breakthrough time and peak concentration of RTD curves of model predictions and water modeling results showed a good agreement (all difference within 12.5 pct) for the 100, 150, and 250 mL KCl cases.

  • 26. Chen, Chao
    et al.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Cheng, Guoguang
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Mathematical modelling of molten alloy mixing in a continuous casting tundish - A hydrodynamic study2015In: Proceedings of the 6th International Congress on the Science and Technology of Steelmaking, ICS 2015, Chinese Society for Metals , 2015, p. 407-411Conference paper (Refereed)
    Abstract [en]

    The emergence of the nozzle clogging have inspired steelmakers to optimize the alloying routine from alloying in ladle to alloying in tundish or in continuous casting mould. Meanwhile, wire injection in tundish has been shown to be successful for postalloying and tundish temperature adjustment. However, there is limited information on the continuous feeding of alloy in tundishes. There are three aspects to be considered: a) "alloy melting", b) "alloy particle dispersion" and c) "liquid alloy mixing". In the present paper, the "liquid alloy mixing" process is studied using CFD (Computational Fluid Dynamics) from a hydrodynamic perspective. In the simulation, the molten alloy is described by the density coupled mixed composition fluid model, which has been verified and validated by water modelling experiments using black ink and KCl tracer mixing in water as a priori. In the present model, the density of the liquid alloy is assumed to be 1.15 or 0.85 times of that of the liquid steel. Thereafter, the denser alloy injection at two positions has been studied, i.e. near the inlet (L1) and at the centre of the tundish (L2). The results indicate that the breakthrough time for the mass fraction of alloy at the outlet are about 100s for both locations. The difference is when the alloy was injected at the center (L2), there is a bypassing flow above the dam. As a result, the mass fraction of alloy at the outlet increases rapidly but the homogeneity in the tundish bath is reduced. Moreover, the denser alloy injection with different velocities was studied. The result shows that the mixing is slightly enhanced during the initial injection stage for the big velocity case. Besides, a test simulation on the mixing of a lighter alloy indicates that the alloy is floating to the top surface.

  • 27.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Taiyuan University of Technology, China; University of Science and Technology Beijing, China.
    Ni, Peiyuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, L. T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Swedish Defence Research Agency, Sweden.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Cheng, G.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    A Model Study of Inclusions Deposition, Macroscopic Transport, and Dynamic Removal at Steel–Slag Interface for Different Tundish Designs2016In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 47, no 3, p. 1916-1932Article in journal (Refereed)
    Abstract [en]

    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.

  • 28.
    Chen, Chao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Ni, Peiyuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, Guoguang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Application of a Unified Eulerian Model to Study the Inclusions Deposition at a Steel-Slag Interface in a TundishManuscript (preprint) (Other academic)
  • 29.
    Eriksson, Robert
    et al.
    KTH, Superseded Departments, Metallurgy.
    Jonsson, Lage
    KTH, Superseded Departments, Metallurgy.
    Jönsson, Pär G.
    KTH, Superseded Departments, Metallurgy.
    Effect of entrance nozzle design on the fluid flow in an ingot mold during filling2004In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 44, no 8, p. 1358-1365Article in journal (Refereed)
    Abstract [en]

    Earlier studies have shown that the mold powder reacts with Steel during filling of the mold during ingot casting of ball-bearing and tool steels, which results in formation of inclusions. Since all inclusions are bad for the material properties for these grades, this is a phenomenon that needs to be avoided. In this study, fundamental mathematical modeling of the filling of an ingot has been used to predict the fluid flow characteristics. A special effort has been made to model the effect of a modified inlet allowing for a larger volume flow. Predictions made by the presently used numerical model, indicates that a successive increase in the opening angle of the inlet nozzle leads to a gradual decrease in the disturbance of the free surface, during mold filling. Furthermore, the horizontal velocities are lower, which results in lower values of the Weber number which is an indication of less chances for mold powder entrapment into steel. It is concluded that both these improvements leads to decreased possibilities for the creation of inclusions in the steel due to interaction with the mold powder.

  • 30. Eriksson, Robert
    et al.
    Tilliander, Anders
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, Superseded Departments, Materials Science and Engineering.
    An experimental study of the velocity field during filling of an ingot mould2003In: Steel research, ISSN 0177-4832, Vol. 74, no 7, p. 423-430Article in journal (Refereed)
    Abstract [en]

    In the present study the velocity field in a 1:3 scale water model of a 4.2-tonne ingot mould was determined using Laser Doppler Anemometry (LDA). The velocity was measured in the horizontal and vertical directions at several different locations along the centre plane of the model. The effect of different volumetric flow rates and water temperatures was also investigated. The reproducibility of the measurements was found to be satisfactory, since the mean velocity at any measurement location had an average difference of around 10% between two fillings. The effect of different volumetric flow rates showed that while decreasing the flow rate, the mean velocity at the bottom turned from an upward direction to a downward direction. At the top of the model the difference between the mean velocities for the different flow rates was less pronounced. An influence of the temperature on the mean velocity could be observed. However, further studies are required to verify this result.

  • 31.
    Ersson, Mikael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Höglund, Lars
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Dynamic Coupling of Computational Fluid Dynamics and Thermodynamics Software: Applied on a Top Blown Converter2008In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 48, no 2, p. 147-153Article in journal (Refereed)
    Abstract [en]

    A novel modeling approach is presented where a computational fluid dynamics software is coupled to thermodynamic databases to obtain dynamic simulations of metallurgical process phenomena. The modeling approach has been used on a fundamental model of a top-blown converter. Reactions between gas-steel, gas-slag, steel-slag and gas-steel-slag have been considered. The results show that the mass transport in the surface area is totally controlled by convection. Also, that a large amount of CO produced during the decarburization might slow down the rate of decarburization in droplets ejected from the bath. For the present simulation conditions reflecting laboratory experiments, it was also seen that the amount of slag (FeO and/or SiO2) created is close to zero, i.e. only gas (CO+CO2) is created as the oxygen jet hits the steel bath. It was also illustrated how an extrapolation of the decarburization rate, sampled from a few seconds of simulation, could be done to get a rough estimate of the carbon content at a later stage in the process as long as the carbon content is relatively high. The overall conclusion is that it is possible to make a dynamic coupling of the Thermo-Calc databases and a CFD software to make dynamic simulations of metallurgical processes such as a top-blown converter.

  • 32.
    Ersson, Mikael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Höglund, Lars
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Dynamic Modeling of Steel, Slag and Gas Reactions during Initial Blowing in a Top-Blown Converter2008In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460Article in journal (Other academic)
    Abstract [en]

    A dynamic modeling approach is presented where a computational fluid dynamics software is coupled to a thermodynamics software to obtain simulations of reactions between steel, slag and gas in a top-blown converter. For each simulation the transport of momentum, energy and mass of species as well as the thermodynamic equilibrium in each cell containing at least two phases was treated. The overall conclusion is that the present calculation procedure is successful for dynamic simulations of interaction between an oxygen gas jet with a melt and a slag. The predicted rate of decarburization was found to agree well with experimental data from laboratory trials. In addition, four cases where simulated for which the temperature, the dissolved carbon content and the dissolved oxygen content were varied. The most important findings from these comparisons were that: i) a higher initial oxygen concentration in the melt yields a larger decarburization rate, ii) carbon content also plays a big role for the desiliconization where a low carbon content is required for desiliconization to take place, iii) decarburization and desiliconization is largely influenced by the temperature at which reactions take place, where low temperature favors desiliconization and iv) the region affected by a lower carbon/silicon concentration (hot-spot region) directly below the jet was approximately 10 mm for the current setup.

  • 33.
    Ersson, Mikael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Höglund, Lars
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Dynamic modelling of steel, slag and gas during initial blowing in a top-blown converter2011In: Steel Grips - Journal of Steel and Related Materials, ISSN 1611-4442, E-ISSN 1866-8453, no 9, p. 41-47Article in journal (Refereed)
    Abstract [en]

    A coupling between computational fluid dynamics (CFD) and thermodynamics has recently been done. In the current model improvement, a more realistic model was developed, where the numbers of gas species and slag phases were increased. For each simulation the transport of momentum, energy and mass of species as well as the thermodynamic equilibrium in each cell containing at least two phases was treated. Read how this calculation procedure can handle dynamic simulations of interaction between an oxygen gas jet, a melt and a slag. How is the agreement between the predicted rate of decarburization and experimental data? Which findings were achieved from the simulation of four cases varying the temperature, the dissolved carbon content and the dissolved oxygen content?

  • 34.
    Ersson, Mikael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Iguchi, Manabu
    Hokkaido Univ, Grad Sch Engn, Div Mat Sci & Engn.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Fluid Flow in a Combined Top and Bottom Blown Reactor2006In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 46, no 8, p. 1137-1142Article in journal (Refereed)
    Abstract [en]

    Physical modeling was done to study the flow field in a cylindrical bath agitated by bottom purging, top lance blowing and a combination of both injection types. A particle image velocimetry (PIV) system has been used to capture the velocity field of all three cases mentioned above. Special attention was paid to the recirculation loop. Top blowing creates a re-circulation loop in a relatively small volume close to the surface, compared to bottom- and combined-blowing. Increasing bottom flow rate moves the center of the re-circulation loop downwards into the liquid. When top blowing is combined with bottom blowing the center of the re-circulation loop is moved downwards into the liquid with increasing top lance flow rate.

  • 35.
    Ersson, Mikael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A Mathematical Model of an Impinging Air Jet on a Water Surface2008In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 48, no 4, p. 377-384Article in journal (Refereed)
    Abstract [en]

    A fundamental mathematical model of the flow field and surface deformation caused by an impinging jet in a top blown reactor has been developed. The results have been validated against water model experiments. More specifically, the predicted penetration depth has been found to agree well with surface deformation measurements and predictions using analytical equations. Furthermore, the predictions of the location of a vortex have been found to agree fairly well with PIV measurements. Calculations were also done to compare the widely used standard k-ε model against the realizable extension of the standard k-ε model to calculate the turbulent conditions of the flow. It was found that the penetration depth caused by the impinging jet on the liquid surface is relatively unaffected by the choice of turbulence model employed. However, when the main re-circulation loop in the bath was investigated there was a clear distinction in the flow fields produced when the two different turbulence models were used.

  • 36.
    Grip, Carl-Erik
    et al.
    Luleå Tekniska Universitet.
    Jonsson, Kjell Olov
    Eriksson, Sven
    Jonsson, Lage
    MEFOS, Luleå, Sweden.
    Jönsson, Pär
    KTH, Superseded Departments, Applied Process Metallurgy.
    Pan, Yuhua
    Theoretical and practical study of thermal stratification and drainage in ladles of different geometry2000In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 29, no 1, p. 30-38Article in journal (Refereed)
    Abstract [en]

    SSAB Lulea, SSAB Oxelosund, MEFOS and Lulea University of Technology have cooperated in developing theoretical models for prediction of thermal stratification and drainage in steel ladles. Predicted results have been verified by measurements done in production ladles with heat weighs of 105 and 200 tonne as well as in a 7-tonne pilot plant ladle. The thermal stratification was measured by thermocouples at different depths. The drainage flow was studied by means of tracer experiments. Numerical simulation models of the steel flow were developed for 7, 105 and 200 tonne steel ladles. The agreement between predictions and measurements was found to be good. The conclusion is that CFD simulation gives a good prediction of stratification and drainage flows in production ladles.

  • 37.
    Grip, Carl-Erik
    et al.
    Luleå Tekniska Universitet.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Physical behavior of slag in a 107 tonne ladle. Production scale experiments and theoretical simulation2000In: ISBN91-7170-606-2, 2000Conference paper (Refereed)
  • 38.
    Grip, Carl-Erik
    et al.
    Luleå Tekniska Universitet.
    Jonsson, Lage
    MEFOS, Luleå, Sweden.
    Physical behavior of slag in a 107-tonne ladle: production scale experiments and theoretical simulation2003In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 32, no 3, p. 113-122Article in journal (Refereed)
    Abstract [en]

    The combined movement of steel, slag and gas in a ladle has been studied with the aid of a multiphase CFD model and measurements in production scale. Comparison of model data and measurements in a production ladle has been carried out for three cases: The ‘open eye’ created during gas stirring, the mixing of top slag during gas stirring in the CAS-OB and finally for studying sculling phenomena. It was found that the simulated ‘open eye’ appears as a central slag-free zone with a surrounding ‘splash zone’ characterized by the fact that steel is found on top of the slag. The simulated ‘open eye’ corresponds to the ‘splash zone’. The predicted gas stirring in CAS-OB gives an efficient stirring of the top slag also. This was confirmed by noting that slag samples taken from the ladle seem to be representative of the mean slag composition. Finally, streamlines during stirring have been compared with sculling and wear observed in the production ladle. Good agreement was obtained.

  • 39.
    Grip, Carl-Erik
    et al.
    Luleå Tekniska Universitet.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, Superseded Departments, Applied Process Metallurgy.
    Prediction of emptying flows in ladles and verification with data fromtrace element plant trials1997In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 37, no 11, p. 1081-1090Article in journal (Refereed)
  • 40.
    Grip, Carl-Erik
    et al.
    Luleå Tekniska Universitet.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jonsson, Kjell Olov
    Numerical predication and experimental verification of thermalstratification in pilot plant and production ladles1999In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 39, no 7, p. 715-721Article in journal (Refereed)
  • 41.
    Hailong, Liu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security, Umeå, Sweden ..
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A simulation study of particles generated from pellet wear contacts during a laboratory testManuscript (preprint) (Other academic)
    Abstract [en]

    In the blast furnace process, material losses occur due to mechanical wear between charged iron ore pellets and are exhausted in the form of dust in the off-gases. A redesigned tribometer combined with a ventilation chamber was developed to identify the dust emission from the mechanical wear contact of pellets. In order to obtain a better understanding of the measurement results, a coupled drift flux with a unified Eulerian deposition model was adopted to investigate particle dispersion and deposition during tests. Two influential factors, namely the air condition (5-20 l/min) and particle size (1-20 µm) were examined. The predicted results were presented by introducing two parameters, namely the measurable fraction and the deposition fraction. For each air condition, the measurable fraction declines while the deposition fraction rises as particle size grows. The critical size of the particles that becomes airborne and captured at the outlet was identified to be around 20 µm. In addition, a high airflow rate supplied at the inlet was observed to be favorable for improving the measurable fraction. Nevertheless, the results show that nearly 50 % of emitted particles (1-20 µm) that failed to be captured during tests. Thus it could be expected that these generated particles would be transported deeply in a blast furnace if they are not efficiently removed from the off-gas. As a consequence, they may influence the quality of the products. Furthermore, the validation of the simulation results against the experimental data was achieved by using the predicted measurable fraction.

  • 42. Hallberg, M.
    et al.
    Jonsson, P. G.
    Jonsson, Lage T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Eriksson, R.
    Process model of inclusion separation in a stirred steel ladle2005In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 34, no 1, p. 41-56Article in journal (Refereed)
    Abstract [en]

    A mathematical model, which can be used as a process model in production, was developed to predict total oxygen content and size distribution of non-metallic inclusions in an agitated steel melt. Using a given pre-deoxidation total-oxygen-content value and calculated velocity and turbulence data (induction or gas stirring), model output can be generated as a function of stirring time. Predicted initial inclusion size distributions were in good agreement with inclusion size distributions quantitatively determined by light optical microscopy and classification according to the Swedish standard SS 11 11 16. Results from simulations carried out for the two types of stirring indicated that the model can predict total oxygen content and inclusion size distribution as a function of time for induction and gas stirring in an acceptable way.

  • 43.
    Hallberg, Malin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Alexis, Jonas
    Swerea-Mefos.
    Modelling of hydrogen and sulphur refining during vacuum degassing in a ladle furnace1999In: SCANMET I, 1999, p. 119-169Conference paper (Refereed)
  • 44.
    Hallberg, Malin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, Superseded Departments, Applied Process Metallurgy.
    The Use of FundamentalModels in Developing Practical Process Control Models for Sulphur and HydrogenRefining2003Conference paper (Refereed)
  • 45.
    Hallberg, Malin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Undvall, Patrik
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Sulfur and Hydrogen Refining during Vacuum Degassing: A New Concept for Process Control2005In: Stahl und Eisen (1881), ISSN 0340-4803, no 5, p. 39-46Article in journal (Refereed)
  • 46.
    Hallberg, Malin
    et al.
    KTH, Superseded Departments, Metallurgy.
    Jonsson, Lage T. I.
    KTH, Superseded Departments, Metallurgy.
    Jönsson, Pär G.
    KTH, Superseded Departments, Metallurgy.
    A new approach to using modelling for on-line prediction of sulphur and hydrogen removal duving ladle refining2004In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 44, no 8, p. 1318-1327Article in journal (Refereed)
    Abstract [en]

    A simplified model has been developed for on-line determination of sulphur and hydrogen contents in the steel during vacuum degassing in an ASEA-SKF ladle furnace at Ovako Steel in Hofors, Sweden. The simplified model was developed based on results from fundamental mathematical model simulations of hydrogen and sulphur refining for a number of cases representing normal production situations. More specifically, mass-transfer coefficients were determined from the simulations and thereafter used to develop separate simplified models for sulphur and hydrogen refining. Predictions from using the simplified process models agreed well with sulphur and hydrogen data from full-scale plant trials. It was therefore concluded that the main purpose of the study, namely to achieve a less time-consuming model suitable for production applications, was fulfilled. The final part of the paper presents how the simplified models can provide engineers or operators with off-line or on-line guidelines on performing the vacuum degassing operation such that quality requirements regarding sulphur and hydrogen contents in the steel product are met.

  • 47.
    Hallberg, Malin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage T.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Undvall, P.
    Sulphur and hydrogen refining during vacuum degassing: a new concept for process control2005In: Stahl und Eisen (1881), ISSN 0340-4803, Vol. 125, no 5, p. 39-48Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper is to discuss how a fundamental mathematical model for prediction of hydrogen and sulphur refining during vacuum degassing can be used to develop on-line process control models. It has first been shown how predictions of sulphur and hydrogen using fundamental mathematical models agree well with measured values from plant trials. These models and analytical equations have thereafter been used to predict hydrogen and sulphur refining for new heats. Here, it was shown that these analytical predictions give very similar results as the fundamental predictions. Thus, it is possible to use the analytical equations in production. It is also discussed how the analytical process models can be used both as on-line or off-line tools in industry.

  • 48. Hellberg, P.
    et al.
    Jonsson, Lage T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, P. G.
    A mathematical model of a blast furnace injection tuyere2005In: Steel Research International, ISSN 1611-3683, Vol. 76, no 11, p. 755-763Article in journal (Refereed)
    Abstract [en]

    One way to further utilise produced gases in an integrated metallurgical plant is to replace oil with gas as a reducing agent in a modern blast furnace. Accordingly, it is of great interest to study the injection of reducing gas into the blast furnace. Therefore, a three-dimensional mathematical model has been developed which simulates the injection of the gas by lances into the tuyere. The model includes the coupled solution of the flow field and the chemical reaction of the gases in the tuyere. Two different types of fuel gas, coke oven gas (COG) and basic oxygen furnace gas (BOF) have been modelled using one injection lance. The modelling technique is presented and discussed as well as the implied results. Furthermore, process parameters such as different gas compositions etc. are investigated using the developed model. Not surprisingly, the main results show that the COG is combusted more completely than BOF gas, which leads to higher flame temperature of the blast putting demand forward to lower the heat load of the tuyere. However, the modelling of the raceway is as far not included in the model, hence the influence of the outlet boundary condition at the tuyere is not reflected in the presented results.

  • 49.
    Hellberg, Per
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage T. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Mathematical modelling of the injection of coke oven gas into a blast furnace tuyere2005In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 34, no 5, p. 269-275Article in journal (Refereed)
    Abstract [en]

    A fundamental mathematical model of the tuyere in a blast furnace has been developed earlier. In this study, the model is mainly used to predict the combustion reactions in the tuyere when coke oven gas is injected through lances located inside the tuyere. The combustion reaction is modelled using a simple reaction scheme with 3 possible reactions that can occur. The influence of the following parameters on the predicted velocities, temperatures and composition of the gas at the tuyere outlet is studied in this paper: (i) injection amount of coke oven gas, (ii) the use of 1 or 2 injection lances and (iii) the influence of the injection angles when using 2 injection lances. It is concluded that the maximum injecting amount using 1 and 2 lances is 10,000 nm(3)/h and 15,000 m(3)/h, respectively. The combustion conditions are better when using 2 injection lances are compared to 1 injection lance and the predicted results are not affected to a large degree when the injection angles are changed.

  • 50. Jauhiainen, Anu
    et al.
    Jonsson, Lage
    KTH, Superseded Departments, Applied Process Metallurgy.
    Modelling of alloy mixing into steel - The influence of porous plugplacement in the ladle bottom on the mixing of alloys into steel in agas-stirred ladle – A comparison made by numerical simulation2001In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 30, p. 242-253Article in journal (Refereed)
123 1 - 50 of 119
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