Physical Simulation Study About The Effects Of The Double-Baffle With Refractory Fillers On Flow Field In Tundish

The double-baffle with refractory fillers is a new type of flow-control device in tundish,and it can also play a role in purifying liquid steel by choosing appropriate refractory fillers.In this thesis,effects of the double-baffle with refractory fillers on flow field and inclusion removal rate of tudish under different process conditions were studied through experiments of the determination of the RTD curves,flow field display,and inclusion simulation.At the same time,the original baffle and the double-baffle without refractory fillers were also studied as comparison.Besides,the influences of calcium-magnesia based refractory on inclusion in liquid steel were studied by thermal experiment when it was used for refractory fillers of double-baffle.The main conclusions are as follow:（1）The results of the RTD curves show that under different process conditions,the overall average residence time decreases with the increase of the inlet flow of tundish.It is found that under the same process condition,the overall average residence time for flow in tundish of the double-baffle without refractory fillers is longer than that of the original baffle,and that the overall average residence time of the double-baffle with the smallest size of refractory fillers is shorter than that of the original baffle and the double-baffle without refractory fillers.It is also found that for the five cases of the double-baffle with refractory fillers,their overall average residence time increases in turn as the size of refractory fillers increases.,and that the overall average residence time of the double-baffle with refractory fillers is longer than that of the original baffle and the original baffle when the size of refractory fillers increases to a certain extent,and that the volume fraction of dead region become smaller in turn as the size of fractory fillers increases.（2）The results of the flow field display show that the surface flow is well formed in the flow zone of outlet when the original baffle and the double-baffle without refractory fillers are respectively used for the tundish,and that dead zone obviously exists at the edge position of the distal end in tundish when the original baffle is used.It is found that the same problem also exists when the double-baffle with the smallest size of refractory fillers is used.It is also found that for the five cases of the double-baffle with refractory fillers,the surface flow in the flow zone of outlet is continuously improved with the increase of fractory fillers size.（3）The results of the inclusion simulation experiment show that under different process conditions,the inclusion removal rate decreases with the increase of the inlet flow of tundish on the contrary,and that under the same process condition,for the five cases of the double-baffle with refractory fillers,the inclusion removal tends to increase gradually as the size of refractory fillers increases.It is found that for removal rate of the simulate particles whose size distribution is 58-75μm and 75^-106μm（corresponding to the inclusion in molten whose size distribution is 21-28μm and 28-39μm）,the double-baffle with refractory fillers,which has the highest removal rate,could be improved by more than 10%,compared with the original baffle.（4）The results of the high temperature experiment show that the number of unit area of inclusion in steel sample after treatment of calcium-magnesia based refractory reduces,and that compared with steel sample after simply remelting,steel samples after respectively remelting together with calcium-magnesia based refractory whose content of Ca O content is 20% and 30%,reduce in the number of unit area inclusion by 12.92% and 25.84%.It is found that calcium-magnesia based refractory has the effect of desulfurization,and that desulfurization effect is more obvious when the content of CaO is 30%.It is also found that after calcium-magnesia based refractory is used in steel molten with high temperature,its integral has no change,and that just at the border area the content of Ca O reduces and the content of MgO increases,and that part of the CaO goes into the liquid steel and cleanliness of liquid steel is improved.