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T. Merder

Abstract

The article presents results of the research that was carried out taking into account the influence of the (impact pads) turbulence inhibitor geometry and its equipment of the working space on the hydrodynamic conditions occurring in T-type tundish. Four different turbulence inhibitors were discussed. They differ in shape and configuration of external walls. The research was conducted basing on the numerical simulations as well as on tests performed on physical water model. As a result of calculations the velocity field distribution, turbulence field and marker concentration distribution in the liquid steel for the tested geometrical variants of turbulence inhibitors were obtained. Worked out RTD curves (Residence Time Distribution) allowed to determine the kinetics of steel mixing (the range of transient zone was estimated), and the percentage participation of the particular flow zones. The test carried out on the water model concerned one of the tested turbulence inhibitors. Research was done to verify the parameter settings of the numerical model applied in calculations. Obtained results gave valuable information about the work of the object after applying different turbulence inhibitors.

Open access

T. Merder

Abstract

In industrial conditions there are situations when the CC machine works under emergency. It can be result of mechanical or electrical causes, breakout of billet or problem with supplying new parts of liquid steel to the CC machine. As a consequence one or two outlets of the tundish should be closed. However, closing one of the outlets influences the hydrodynamic and thermal conditions occurring in the tundish. Thus, the important information is which of the outlets should be closed to conduct further continuous casting process correctly.

The following research was conducted to analyze the influence of liquid steel flow behaviour in the multi-strand tundish when all outlets do not work. Such problem was solved by means of numerical methods based on Navier-Stokes equations (k–ɛ standard turbulence model). Numerical simulations were done using the educational version of CFD program (Computational Fluid Dynamics) – ANSYSFluent. As a result forecasted velocity fields and RTD curves (Residence Time Distribution) were obtained. RTD characteristics were used to determine kinetics of liquid steel mixing and also to calculate parts of particular flow areas for studied cases.

Open access

T. Merder, M. Warzecha and P. Warzecha

In order to increase the efficiency and quality of the steel-making process a numerous studies are conducted at the various stages of the process, including continuous casting of steel. Researchers still search for new models and improve existing one, so that the specific of the process is accuratelly reproduced. One way to increase the accuracy of numerical simulation, is to apply the LES (Large Eddy Simulation) method to simulate steelmaking processes.

The article presents the results of numerical analysis on the flow characteristics (RTD curves) of liquid steel in the tundish facility for the continuous casting of steel. Numerical simulations have been performed using RANS (Reynoldsaveraged Navier-Stoke) and LES methods, and those results have been verified in industrial conditions.

Open access

M. Warzecha, T. Merder and P. Warzecha

Abstract

The liquid steel flow structure in the tundish has a very substantial effect on the quality of the final product and on efficient casting conditions. Numerous model studies are being carried out to explain the effect of the tundish working conditions on casting processes.

It is necessary to analyze the structure of liquid steel flow, which is strongly supported with numerical modeling. In numerical modeling, a choice of a proper turbulence model is crucial as it has a great impact on the flow structure of the fluid in the analyzed test facility. So far most numerical simulations has been done using RANS method (Reynolds-averaged Navier-Stokes equations) but in that case one get information about the averaged values of the turbulent flow. In presented study, numerical simulations using large eddy simulations (LES) method were used and compared to RANS results. In both cases, numerical simulations are carried out with the finite-volume commercial code AnsysFluent.

Open access

J. Pieprzyca, Z. Kudliński and T. Merder

Abstract

The formation of the cast strands’ primary structure is a very complex process in terms of the thermodynamics and physicochemical. It occurs during solidification and crystallization of the liquid steel in the crystallizer and in the secondary cooling zone of the CC device. On the basis of the experience gained in the industry and knowledge arising from theory of metals and alloys solidification it can be concluded, that substantial influence on the shape of cast strands primary structure have the temperature of overheating of the liquid steel above liquidus temperature and solidification velocity. A proper control of those casting parameters allows to obtain the cast strands with desired primary structure. In the one and two-way symmetric devices regulation like this is not problematic, in the multi-way devices - specially in the asymmetric - causes a series of problems. In those devices can occur a major temperature difference in each outlet zone of the tundish working space caused by i.e. the distance length diversity of liquid steel stream from the inlet to each outlet and by disadvantageous layout of liquid steel flow zones (turbulent flow zone, plug flow and dead zones) in working area of tundish. Particularly high values of those diversity can be expected in the asymmetric tundishes.

The article presents results of laboratory research - model and industrial regarding impact of the liquid steel overheating temperature, but also heterogeneity of the temperature fields in the tundish on primary structure of the cast strands.

Open access

T. Merder, M. Saternus and P. Warzecha

Abstract

Both primary and secondary aluminium have to be refined, especially by barbotage process. To know better the mechanism of blowing argon through aluminium in reactors with rotary impellers, numerical modelling is applied. It allows to obtain useful information like: the level of velocity field or participation of gaseous phase. However, numerical analysis requires choosing the proper model which would describe the physical phenomena occurring in the process. So, AnsysFluent code was used in the research. It allows to calculate the two-phase liquid flow for the 2D and 3D co-ordinate systems. Results of calculations for the 3D case can describe more accurately the spatial picture of the movement trajectory of the blown gas bubbles. Calculations were done for the flow rate of refining gas equal 5 dm3/min and for two cases: when there was no rotation and with 300 rpm rotary impeller speed.

Open access

T. Merder, J. Pieprzyca, M. Warzecha and P. Warzecha

Abstract

The article demonstrates results of modelling research tests concerning the analysis of possibilities of blowing gas into the metal bath at high flow rates in a steel ladle with a nominal capacity of 50 Mg. Various configurations concerning of gas introduction into the steel ladle were analysed. There were considered cases of blowing into the metal bath via one, two or three purging plugs, being installed on the bottom and via additional support for blowing the gas from the top through the lance.

Results obtained from the water model of the reactor were verified with the results of numerical simulations.

Open access

M. Saternus, T. Merder and J. Pieprzyca

URO-200 reactor belongs to batch reactors used in refining process of aluminium and its alloys in polish foundries. The appropriate level of hydrogen removal from liquid aluminium can be obtained when the mixing of inert gas bubbles with liquid metal is uniform. Thus, the important role is played by the following parameters: flow rate of refining gas, geometry of the impeller, rotary impeller speed.

The article presents the results of research conducted on physical model of URO-200 reactor. The NaCl tracer was introduced to water (modelling liquid aluminium) and then the conductivity was measured. Basing on the obtained results the Residence Time Distribution (RTD) curves were determined. The measurements were carried out for two different rotary impellers, flow rate equaled 5, 10, 15 and 20 dm3/min and rotary impeller speed from 250 to 400 rpm every 50 rpm.

Open access

J. Pieprzyca, T. Merder, M. Saternus and H. Kania

Abstract

The article presents the results of research concerning the change of liquid steel flow and mixing in the T-type tundish. It has been installed in one of polish steel plants. Continuously changing market conditions have forced the change in the range of cast strand. As a consequence the new control system of liquid steel flow had to be applied. Up to now a baffle with notch has played the role of steel flow regulation. It was placed between the inlet and channel zones of a tundish. However such solution was not satisfactory. Therefore, a new flow control equipment was designed - baffles and different constructional variants of turbulence inhibitors. To estimate the efficiency of their functioning and in the same time their influence on the tundish work, modelling research was carried out. The research was also complemented by numerical simulations. The article presents results of such research as well as experimentally and numerically determined RTD curves of mixing (Residence Time Distribution).

Open access

J. Pieprzyca, T. Merder and M. Saternus

The way and speed of steel flux flowing into mould of continuous casting (CC) machine belong to the important parameters characterizing the steel continuous casting process. Such flux causes determined kinds of steel circulation, which together with simultaneous steel crystallization influence the creation of ingots primary structure and quality of its surface.

The article presents the results of modelling research which aim was to determine the optimal location of submerged entry nozzle in square moulds (130 x 130 mm and 160 x 160 mm) of CC machine. Such a research was carried out for two different grades of steel (low-carbon steel and high-carbon steel), which feature different parameters of casting.