Research On Slag Entrapment Critical Liquid Height In Continuous Casting Tundish

During the stopping casting process of tundish, the conflux vortex formed in the discharge area generates slag entrapment accurs while the liquid surface declining. This phenomenon worsen the steel quality, decline the quality of casting billet and decrease the yield of metal. This dissertation carries out a research on the conflux vortex formation in tundish with the method of numerical simulation and physical simulation, and analyses the influential factors of the critical liquid level when slag entrapment appear. The influential factors includes density and viscosity of molten steel and slag, thickness of slag layer,nozzle diameter, stopper height and the close order of casting flow.The numerical simulation in this paper is accomplished with a fluid calculation software named FLUENT6.3.26. A three-dimensional geometrical model of5-strand tundish is built, and then the flow field area are meshed. The RNG k-ε and VOF model is usde as turbulence model and multiphase flow model. The numerical simulation of the stopping casting process of tundish is done after the boundary conditions and initial condition were set. The result of simulation shows, the conflux vortex gradually develops from bottom to upper. For sake of preventing and inhibiting the conflux vortex, it is necessary to take measures nearby the nozzle.In order to study on the influence factor, numerical simulation result of stopping casting process of tundish with different conditions have done. The result shows, larger molten steel density, larger slag density, larger slag viscosity and lower molten steel viscosity, the stopping molten steel level is declined; choose reasonable close order of casting flow is be conductive to decline the critical level; the critical level decreased17.4mm when the thickness of slag layer adds50mm; the critical level rise22.1mm when the nozzle diameter augment60mm; the critical level decreased14.9mm when the stopper height descend40mm. Above all, increase the thickness of slag layer, decrease the nozzle diameter and stopper height is helpful to decline the critical level.In the end, water model experiments are taken to prove the consequence of numerical simulation. As water model experiments with different nozzle diameter was accomplished, the result indicates that the critical level of tundish with60mm and90mm nozzle diameter is81.5mm and95.5mm. Contrasts with the numerical simulation result in same condition, the maximum error is7.3%. It demonstrates that numerical simulation are capable of simulate the conflux vortex and slag entrapment during the stopping casting process of tundish.