Effect of ladle shroud immersion depth on unsteady three-phase flow in continuous casting tundish during ladle change-over process
摘要
The transient phenomena of re-oxidation and slag entrapment occurring in the tundish during the ladle change-over process have been proven detrimental to clean steel production. Therefore, an unsteady three-phase turbulence model, coupling velocity, temperature, and phase field was established to study the effect of the ladle shroud immersion depth on the slag eye formation, slag entrainment, slag dragging, air dragging, and flow characteristics during the ladle change-over process of a two-strand tundish. The results showed that reducing the immersion depth decreases the high-velocity region area under the slag layer in the quasi-steady process. During the emptying stage, as the molten bath level gradually decreases, the outlet temperature exhibits a trend of initially decreasing and subsequently increasing across all three shroud immersion depths. However, under a 210 mm shroud immersion depth, molten slag and air are dragged into the shroud, forming slag droplets and causing significant fluctuations, with a maximum scalar velocity of 0.0764 m/s at the monitoring point. In the filling stage, air and molten slag are dragged into the molten bath, forming bubbles and slag droplets at an immersion depth of 210 mm. Bubbles are observed within the molten slag layer, which can readily cause an emulsification phenomenon, making it easier to be dragged as slag droplets. Additionally, the slag eye area measured under 210 mm immersion depth at 45 s is 0.303 m2, while the maximum scalar velocity of 2.4259 m/s is detected at 12 s. At an immersion depth of 360 mm, the average area of the slag eye is minimized to 0.06268 m2, with corresponding variances of 0.006753, representing the optimal immersion depth.