Study On The Optimization Of Bottom Argon Blown In 120t Ladle

As a secondary refining technology,ladle bottom argon blowing refining has been widely used because of its advantages of simple operation,low cost and good refining effect.In order to improve the effect of ladle argon blowing refining and adapt to the demand of"speeding up the pace,improving production capacity and ensuring quality",120 t bottom blowing argon ladle in domestic steel mill is taken as the research object,The flow field and temperature field in ladle were simulated by physical simulation and numerical simulation.In this paper,the influence of bottom blowing layout scheme on the characteristics of flow field and temperature field in ladle and the temperature drop of molten steel was revealed.The optimal bottom blowing layout scheme was determined.Provide key technical parameters for improving blowing efficiency.The main results of this paper are as follows:(1)In the same arrangement,with the increase of bottom blowing argon flow rate,the mixing time of ladle decreases.When the bottom blowing argon flow rate is greater than 320NL·min-1,the decrease trend gradually decreases.Changing the bottom blowing arrangement of ladle will obviously change the mixing time of ladle.When the bottom blowing arrangement is at 0.67R-60°,the mixing time is the shortest.(2)Slag entrapment mainly appears in two positions.One is around the slag eyes,and the other is at the junction of the two slag holes.With the increase of bottom blowing flow rate,the degree of slag entrapment in ladle becomes more severe and the slag eyes area becomes larger.When the slag layer thickness is 20 mm,the slag eyes area increases from 80 cm2 to 452 cm2 when the bottom blowing flow rate increases from 40 NL·min-1 to 400 NL-min"1.With the increase of slag layer thickness,the degree of slag entrapment becomes more severe and the slag hole area decreases.When the thickness of slag layer increases to 30 mm,the bottom blowing flow rate increases from 40 NL·min-1 to 400 NL·min-1,and the slag hole area increases from 50 cm2 to 437 cm2.(3)Two vortex,one large and one small,will be formed on both sides of the gas-liquid two-phase zone in the ladle during the bottom blowing process.With the increase of bottom blowing angle,the small one gradually increases and the large one gradually decreases.Changing the bottom blowing flow rate and the circumferential radius of the permeable brick has little effect on the vortex characteristics.(4)With the increase of bottom blowing flow rate,the average speed of molten steel gradually increases,and the dead zone ratio gradually decreases.With the increase of the included angle of bottom blowing permeable bricks,the average speed of molten steel gradually decreases,and the dead zone ratio gradually increases.With the increase of the circumferential radius of the bottom blowing permeable brick,the proportion of ladle dead zone increases.When the bottom blowing flow rate is 180 NL·min-1,the average velocity of molten steel in the original scheme is 0.14 m·s-1,and the dead zone ratio is 4.5%,while the average velocity of the optimized scheme is 0.18 m·s-1,and the dead zone ratio is 2.2%.(5)During the standing process of molten steel,the temperature is obviously layered,and the temperature at each point in the ladle is quite different.With the increase of standing time,ladle temperature delamination intensifies.Argon blowing at the bottom of ladle can obviously reduce the temperature stratification of molten steel.With the increase of argon blowing time,the temperature field of molten steel becomes more uniform.When argon is blown for 15min,the maximum temperature difference of the original scheme package is 23.4 K,and that of the optimized scheme package is 16.8 K.(6)The purity of optimized GCr15 bearing steel is improved.The inclusion of Class A coarse series is reduced from 1.5 to 0.5.The inclusion of Class B coarse series is reduced from 1.5 to 0.5,and the inclusion of Class C is reduced from 1.0 to 0.5.It meets the requirements of high quality steel.