Continuous casting comprises thermal, mechanical and chemical processes running in a complex system that contains a number of elements, such as a solidifying steel strand, a mould with an oscillation mechanism, a withdrawal mechanism, a water cooling subsystem with nozzles, several control subsystems , etc. An external observer might see the process as robust and stable, but in reality there are fluctuations in the internal thermal and mechanical quantities, reflected in the structure and quality of the product. The research on unsteady behaviour of the quantities such as a solidifying strand temperature field, solid shell thickness and metallurgical length was conducted using an industrial diagnostic system DGS complemented with special measurement equipment and a thermal numerical model. Selected results of the monitoring and simulation of the non-standard process states are shown and analysed in the paper. Methods for determining the boundary conditions for the numerical model are also presented. The effect of the Leidenfrost phenomenon on the heat-transfer coefficient during water cooling by nozzles is also discussed. Since the determination of precise and immediate boundary conditions has technical limits, the model provides only smoothed values in time and space. As knowledge of the instantaneous state of the fluctuating process is a prerequisite for achieving quality and defect-free production, it is appropriate to complement the thermal numerical model by on-line monitoring of the machine's internal state. The results of the simulations are closely linked to the real process data.
The article describes a methodology for determination of permeability and inertial resistance coefficient of filter inserts used for the separation of solid and liquid impurities in natural gas. The parameters of the filter inserts are described by analytical relations and their real values are obtained experimentally. The realized experiment was focused on the measurement of the pressure drop in the insert, with which both permeability and inertial resistance coefficient were possible to be expressed. The experiment was performed on the reduced physical model of the filter separator, which was constructed at a scale of 1:127. During the experimental measuring the working medium was pressure air. In a real filter separator there is compressed natural gas used as the working medium. The reduced model, therefore, had to meet the basic requirement of similarity of flowing in the model and the real object, which was based on equality of the Reynolds criteria for the work and the model.
Numerical models of solidification and cooling of continuously cast billets or blooms are used both in research and in operational conditions to predict solid shell thickness, metallurgical length, solidification rate etc. The numerical model must be verified according to real values of quantities. Although several different quantities can be used to verify the model, most often the models are verified by comparing the calculated and measured surface temperatures of the strand in the secondary and tertiary cooling zones.The casting process is influenced by a number of known and hidden parameters, often time-varying, which are reflected in the measured surface temperatures, but which cannot be incorporated into the model due to a lack of information to define the exact boundary conditions. For the purposes of model verification, it is therefore necessary to revise the measured data. It is not enough to use only mathematical methods to process data without knowledge of the casting process, because uncertainties and temperature fluctuations have different and often difficult to detect causes. The article deals with sources of temperature uncertainties and fluctuations and methods of extraction of relevant values from measured signals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.