Simulation Study On Inclusion Remove By Gas Bubbling Tundish

In order to study the advantages and characteristics of gas bubbling tundish applied in clean steel production,the flow field characteristics of gas bubbling tundish and the removal method of inclusions in tundish were analyzed comprehensively.A reasonable mathematical model is established to simulate the flow field of the gas bubbling tundish.Based on the EulerEuler method and k-? model,the main control variables are blowing position,blowing flow rate,bubble diameter and casting speed.According to the simulation results,the minimum response time,average residence time,dead zone volume ratio,piston zone and mixed zone volume ratio are analyzed.The results show that argon blowing at the bottom of tundish can make two large circulating flow fields on both sides of the gas curtain,improve the flow state of molten steel and extend the residence time of molten steel in the tundish.When the position of the gas curtain is 1800 mm away from the center of the nozzle and the blowing volume is 1.2 m3/h,the flow field reaches the best state.Compared with the conventional tundish,the average residence time of steel in gas bubbling tundish was extended by 10.4%,and the dead zone volume was reduced by 41%.By comparing the influence degree of each parameter on the flow field of molten steel,it is found that the position of air curtain and gas flow volume have a great influence on the flow field of molten steel,while the bubble diameter and the casting speed have little influence on the flow field.This topic through the use of DPM moddel based on Euler-Lagrangian method to simulate inclusions floatation removal,blow gas and gas curtain position is still the main factors affecting inclusion floatation removal,when the gas curtain is 1800 mm away from the center of the nozzle,and the blowing volume is 1.2 m3/h,the inclusion removal rate is highest,about 26.2%higher than that of conventional tundish,mainly reflected in the below 60 ?m for the improvement of medium and small size of the inclusion removal rate,more than 60 ?m inclusions are not obvious.Liquid steel as well as the movement of bubbles in bubble removing inclusions is a big topic,the buoyancy of small bubbles in the liquid steel is smaller,the floating rate is low,vulnerable to liquid steel while under the influence of turbulence diffusion,gets phase distribution is wider,can improve the probability of bubble capture the inclusions,the calculation results show that when the bubble diameter is 2 mm,adhesive removal rate of inclusions are bubbles is 11.4%.The Euler method was used to coupling the PBM population equilibrium model to study the collision polymerization growth behavior of inclusions in molten steel under the action of turbulent flow field and the change of the number and density of inclusions under different casting speeds.The casting speed had a certain influence on the collision polymerization of inclusions in the early and middle stages,but had little influence on the final result.According to the calculation of the inclusion collision removal rate under the optimal conditions,the results show that the inclusion collision removal rate of tundish of air curtain retaining wall is about 73%higher than that of conventional tundish,reaching 8.9%.The removal rate of inclusions in tundish of gas bubbling was 28.4%higher than that of conventional tundish when all the removal methods of inclusions in tundish were taken into consideration.