Research On Molten Steel Flow And Heat Transfer In Continuous Casting Tundish

With the development of steel-making technology, it becomes more and more important to improve the cleanliness and quality of casting steel. The tundish which serves as a refractory container before the steel solidification has a very important influence on steel quality. The conditions of steel flow in tundish perform a vital role in decreasing the secondary oxidation of steel, lengthening the residence time of steel and making the inclusions well folated. Therefore, it is very significant both in theory and practical application to study and analyze the flow field and temperature field of molten steel in tundish and try best to make them proper.In this paper, according to the fact of No.7 billet CC tundish at Kunming Iron and steel (group) Company Ltd, several production quality problems in a billet tundish had been investigated. The physical and mathematical simulation methods were used. The experiment model was built and the experiments were done based on the Frpude similarity and by similarity principle. The mathematical model, describing the flow phenomena in the tundish, was established. Meanwhile the Fluent commercial software was used to calculate the steel flow and heat transfer in tundish. By comparing the influence of different schemes of designs for tundish on fluid behavior, it was available to make sure the best inter-structure design for the tundish. With the optimized tundish, flow control devices and the immersion depth of long nozzle were all optimized.The results showed that the molten steel stay short time on average and the inclusions have little opportunities for floation in tundish without flow control devices. The inner structure of B program for tundish is better, but flow control devices are still needed to improve flow pattern. The simple barricade can effectively prevent the liquid steel flowing directly to the most center nozzle and greatly reduce the influence of steel injection to the most center nozzle. Using 2# simple barricade which can raise plug flow volume by 19.0% and decrease dead zone volume by 19.7% is an effective way to improve fluid flow behavior in tundish. The uses of weirs can obviously restrain the turbulent of injection zone and molten steel can also be assigned more effectively to each outlet in tundish. Using 3# weirs which can raise plug flow volume by 27.5% and decrease dead zone volume by 29.9% can further improve fluid flow behavior in tundish.Adding flow control devices, in varying degrees, can improve fluid flow behavior in tundish. Using suitable flow control devices can increase average residence time of moten steel, raise plug flow volume and decrease dead zone volume. The flow patterns of molten steel in tundish with flow control devices are in favor of the inclusion floating up and removment. The use of flow control devices in tundish can meet the demand of varieties steel production and ultimately improve the quality of the slab.