Physical Modeling Of Fluid Field And Structure Optimization In Two-strand Tundish And Mold

With the development of high efficiency continuous casting,the metallurgical effects of tundish and mold is vital.The optimization of structure and flow field of tundish and mold can improve the flow field of molten steel,promote inclusion floating up,avoid secondary oxidation and slag entrainment of liquid steel.It will ensure the purity of the molten steel and stable operation of continuous casting process to improve casting quality.In this paper,the physical modeling of flow field in 55 t two-strand slab continuous casting tundish and mold was conducted,and the structure of tundish and operating parameters of mold were optimized.The similarity ratio between model and prototype was 1:3.According to structures of the dam and weir designed,the appropriate structures could be selected by the measurement of RTD curve and observation of flow field.The reasonable distance between dam and weir and distance between dam and long nozzle were optimized further and the removal rate of inclusion under the optimization situation was contrasted with that under no dam and weir situation.The paper also studied the influence of argon blowing flowrate,immersion depth of SEN and casting speed of mold on the surface fluctuation,surface exposure and impact depth of the liquid steel.The results of physical modeling of tundish indicate that the fluid flow state could be changed and the path of the fluid flow could be prolonged as well as the average residence time was improved after using dam and weir.But there were some dead zones after fluid passed through the dam and weir.After optimization,that the distance between dam and weir was 290 mm and the distance between weir and the long nozzle was 383 mm was best.The longest average residence time was 351 s and the minimum volume fraction of dead zone was 19.0% under the above situation.Compared with that no dam and weir were used,the average residence time increased by 65 s and the dead zone volume fraction decreased by 15.0%.The removal rate of inclusions under optimization situation was better than that with no dam and weir situation.Furthermore,the removal rate of inclusions remarkably increased with the increasing of inclusions particle size.The results of physical modeling of mold indicate that with the increase of argon blowing flowrate,the surface fluctuation became severe,the surface exposure increased and impact depth reduced.With the increase of immersion depth of SEN,the surface fluctuation generally showed a trend of increasing,the surface exposure increased and impact depth also generally presented a trend of increasing.With the increase of casting speed,the surface fluctuation increased,the surface exposure decreased and impact depth generally increased gradually.