Optimization Of Submerged Entry Nozzle Structure In A Mold Of 1650 Continuous Caster

For the mold used in the slab continuous casting,the appropriate properties such as cooling performance and stabilities are required to meet the requirements of continuous process.The purity of the steel is also required to improve the slab quality.The structure and process parameters of submerged entry nozzle(SEN)have a great influence on flow field of molten steel in the mold.The reasonable flow field makes steel surface become stable and prevent slag entrapment,which plays a very important role in improving the purity of the liquid steel,and avoiding the slab surface and internal defects.In this study,based on a 1650 continuous casting mold in real,mathematical and physical modellings were performed to investigate some flow phenomena to optimize the flow field in the mold.Also,the SEN immersion depth,bottom structure,side port area ratio and casting speed were studied to explore the influence factors on flow field in the mold.The flow field,the temperature field and the inclusion removal were calculated by applying the commercial software Fluent.For the molds with sections of 230mm×950mm and 230mm×1650mm sections,The effects of the structure parameters of SEN and the operating parameters on the surface fluctuation,slag entrapment and the impact depth were investigated by performing the physical and mathematical modeling for the casting speed of 1.4m/min,1.65m/min and 1.3m/min.A flow rate value of 0.1m3/h was applied for the comparison.The results showed that,the level fluctuation of the 1#SEN was volatile and slag entrapment phenomenon was obvious.The free surface was smooth and the slag entrapment phenomenon was not observed by using the 6#SEN,Finally,6#SEN was confirmed as the optimum SEN and the suitable immersion depth was 57mm to 70mm(130mm to 160mm for the prototype mold).In the numerical simulation,the impact depths agreed well with those of the physical experiments.In the mold with section of 230mm×1650mm,the flow velocity of the export by using 1#SEN was higher than that of 6#SEN.When the immersion depth was 130mm,the surface temperature in the mold was decreased by 7.31K when 1#SEN was applied compared with using 6#SEN.The temperature at the bottom of the mold by using 1#SEN was 1.18K higher than that of 6#SEN.Consequently,the flow field and the temperature field were more favorable when using 6#SEN.The floating and removal of inclusions in the molds with the section of 230mmx950mm and 230mm×1650mm were calculated by the discrete phase model(DPM)at an immersion depth of 130mm.The results showed that,the removal rate was low and no difference between the 1#SEN and 6#SEN in the 230mmx 1650mm mold when the inclusion diameter was 10?m.When the inclusions diameter was higher than 50?m,the removal rate by using 6#SEN was higher than that of the 1#SEN.