T. Merder

Optimization of a Six-Strand Continuous Casting Tundish: Industrial Measurements and Numerical Investigation of the Tundish Modifications

The main differences in the transient zone extent between the individual strands for the former industrial six-strand tundish configuration is the basis for undertaking this study. The aim this study was to improve the casting conditions by proposing the optimal equipment of the tundish working space. For economic reasons, only the variants with different baffles configurations were considered. It was also dictated by the simplicity of construction and the possibility of its implementation by the base operating steel mill. In the current study, industrial plant measurements and mathematical modeling were used. Industrial experimental data were used to diagnose the current state of the industrial tundish and then validate the numerical simulations. After this, the influence of different baffle configurations installed in the tundish on the steel flow characteristic was modeled mathematically. Residence time distribution (RTD) curves are plotted, and individual flow shares for the investigated tundish were estimated based on the curves. Finally, the industrial plant was rebuilt according to the numerical results and additional plant measurements were performed. A result of the appearance of the baffles in the tundish working space was the reduction of the transient zone extent. The results indicate the increasing share of the dispersed plug flow and a decreasing share of the dead volume flow, with a practically unchanging share of well-mixed volume flow in the modified tundish.

Numerical and Physical Modelling of Aluminium Barbotage Process

Today the aluminium refining process, especially barbotage is one of the most essential necessary technological stages in obtaining aluminium. It gives possibility to remove undesirable hydrogen and non-metallic and metallic inclusions from aluminium. Phenomena that take place during the barbotage process are rather complicated, but the knowledge about their character enables to optimize and control this process. Modelling research is used to outline these phenomena. Physical and mathematical modelling can be applied in carrying out aluminium barbotage process. Mathematical modelling uses numerical methods to solve the system of differential equations. The paper presents results of physical and numerical modelling of the refining process taking place in the continuous reactor URC-7000. Physical modelling was carried out for the different flow rate of refining gas (argon). It was in the range between 2 to 25 dm3/min. Numerical calculation was done using commercial program in Computational Fluid Dynamics (CFD). Model Volume of Fluid (VOF) was applied in modelling the multiphase flow. Obtained results were compared in order to verify the numerical settings and correctness of the choice.

Physical Modelling of Metallurgical Processes

Today physical modelling is a commonly used tool in modelling metallurgical processes. It can be applied both in steel metallurgy and non-ferrous metals metallurgy processes. It gives the opportunity to determine the hydrodynamic conditions of the processes. Although, the flow of mass and gas is not totally presented by such modelling, this kind of research is very often and willingly used. That is because it is really difficult to conduct experimental research in industrial conditions. Typically water is used as a modelling agent, so the physical modelling is not as expensive as the one carried out in industrial conditions. To obtain representative research from physical modelling the physical models have to be built according to the strict rules coming from the theory of similarity. The results obtained from the experimental test on the physical model, after verification, can be transferred to the real conditions. The article shows the obatined results coming from physical modelling of the steel production process. In the Institute of Metals Technologies of Silesian University of Technology the appropriate test stand was built to simulate the steel flow and mixing in the ladle. The visualization results have been presented. To simulate processing condition during aluminium refining additional test stand was also built. The exemplary results have been shown for different flow rate of gas, rotary impeller speed and different shapes of impellers. All presented results have been discussed and presented for the perspectives of further research.

Modeling Study of the Influence of Subflux Controller of Turbulence on the Molten Steel Flow in Tundish

The objective of the study is to diagnose the current condition of the two-strand tundish. The investigated object is a “T”-type tundish. The nominal capacity of the tundish is 7.5 tonne of liquid steel. By the mathematical simulation, fluid flow and heat transfer of molten-steel in a tundish of a billet caster under different conditions (bare tundish and tundish with flow control device) are analyzed. Three variants of subflux controller of turbulence configurations in the tundish are tested. Numerical simulations of are carried out with the finite-volume commercial code FLUENT using the realizable k- turbulence model. Liquid steel velocity, temperature, turbulent kinetic energy and Residence Time Distribution (RTD) characteristic have been obtained as a result of mathematical calculations. The RTD curve is used to estimate the different volumes such as plug volume, dead volume and mixed volume inside the tundish. The ratio of mixed to dead volume, which indicates the mixing capability of a tundish, is estimated.

Numerical and Physical Modelling of Aluminium Refining Process Conducted in URO-200 Reactor

At present both primary and secondary aluminium needs to be refined before further treatment. This can be done by barbotage process, so blowing small bubbles of inert gas into liquid metal. This way harmful impurities especially hydrogen can be removed. Barbotage is very complex taking into consideration hydrodynamics of this process. Therefore modelling research is carried out to get to know the phenomena that take place during the process better. Two different modelling research can be applied: physical and numerical. Physical modelling gives possibility to determine the level of gas dispersion in the liquid metal. Whereas, numerical modelling shows the velocity field distribution, turbulent intensity and volume fraction of gas. The paper presents results of physical and numerical modelling of the refining process taking place in the bath reactor URO-200. Physical modelling was carried out for three different flow rate of refining gas: 5, 10 and 15 dm3/min and three different rotary impeller speeds: 0, 300, 500 rpm Commercial program in Computational Fluid Dynamics was used for numerical calculation. Model VOF (Volume of Fluid) was applied for modelling the multiphase flow. Obtained results were compared in order to verify the numerical settings and correctness of the choice.