MSE Graduate Seminar: Demystifying Complex Multiphase Flow Phenomena in Continuous Casting Processes using Advanced Imaging Techniques

Abstract:

Steel is one of the commonly used materials for several applications such as heavy equipment, structural, automotive, oil and gas pipeline, windmill, pressure vessels etc. Steel products are widely used in these applications because of their excellent mechanical properties at relatively lower cost. Steel is made through different complex metallurgical processes. These complex processes involve the interactions of various phases such as liquid steel, slag, and gas. In case of steelmaking and casting vessels, multiphase flows generally consist of a continuous phase such as liquid steel, and one or more dispersed phases such as gas bubbles and/or slag droplets. Occasionally, these multiphase flows undergo some undesired interactions. These interactions invite various casting defects to the steel which may deteriorate the mechanical properties, drastically. Due to the occurrence of these defects, several losses such as lower plant yield, delayed delivery schedules, and increased reworking etc. occur to impact overall sustainability of the steel plant.  To understand and reduce the occurrence of such multiphase flow driven defects, physical and mathematical modeling approaches are utilized. In the current study, behavior of dispersed phase under the flow of continuous phase is demystified with the help of advanced imaging techniques. Both bubbles and slag droplets are studied for different metallurgical vessels to develop mathematical models for each case. In case-1, behavior of bubbles formed in a continuous casting mold are studied which includes the development of mathematical model for the estimation of Bubble Size Distribution and the Dimensionless Area of Mold Slag Exposure. In case-2, behavior of ladle slag droplets is studied to estimate the Affected Area of Tundish Covering Slag Layer. In both the cases, shadowgraphy imaging technique was used in association with a high speed high resolution camera. Mathematical models were validated against data obtained from lab experiments and there was a strong agreement between the results.