Modelamento matemático da inertização de distribuidores para lingotamento contínuo de aço

Abstract

With the increasing competitiveness of world steel market, the reduction of operational costs is key to the survival of steel producers. Inertization (or purging) of the tundish before its initial filling or ladle changes is a well-established procedure to reduce productivity and metallic yield losses that occur in these stages due to the contact between steel and air. The literature, however, lacks detailed information on the subject. In this work, the inertization practice for a 17.7 tons of long steel continuous casting tundish has been studied by means of a three-dimensional non-isothermal mathematical model. The model considers a single gaseous phase composed of argon and air. Turbulence was accounted for with the standard k- model. The calculations were carried out using the commercial CFD software ANSYS CFX. Different configurations of the inertization system were simulated and a novel approach was utilized to discuss model findings. The results indicated that the present configuration is ineffective and new ones were suggested. In addition, the heat loss arising from the inertization of a tundish with hot-start and the pickup of total oxygen, nitrogen and hydrogen that occur during tundish filling due to steel-air interaction were estimated. It was found that, since purging is well-designed, the heat loss caused by inertization is negligible. It was also identified the possibility of reducing hydrogen pick-up by means of inertization, benefit that has received little attention in the literature.