Mathematical Simulation Of Slag/Steel Interface And Heat Transport Behavior During Teeming Process With Argon Injected Into Ladle Around The Tapping Hole

The technology of preventing slag down during casting process in ladle is one of the main concerning problems in the production,and the proper operation remains to be adopted to control the roughing slag becomes an key point to produce high purity steel at lower price.The main methods to reduce the roughing slag include floating valve inclining the ladle bottom and the method by changing the shape of the water outlet port,which all show a certain defects.A innovated process by blowing argon around the tapping hole is expected to control the roughing slag at a low cost,and the simulation study focused on the behavior of the steel-slag interface and the temperature field will afford the theoretical basis for the development of the this new process.CFD software has been adopted to simulate the argon blowing process around the tapping hole as well as the ladle pouring process based on the 145 ton ladle from one steel plant.Other commercial software such as Fluent,Gambit and Tecplot have also been used in this paper.The calculation process is based on the VOF gas-slag-steel three phase flow model,DPM injection model,nonconstant model,heat transfer model as well as standard k-?turbulent model.The influences that different gas blowing rates and its device dimensions as well as the thickness and viscosity of the slag layer have on the controlling of the roughing slag have been investigated.The temperature field behavior in the standing process and the pouring process of the ladle has been studied to shed light on effect that different gas blowing rates have on the temperature behavior.The main conclusions obtained according to the simulation results are summarized as follows:(1)Blowing argon around the tapping hole during teeming process can reduce the critical height of vortex and the height of drain sink.Compare with no argon injection,the critical height of vortex decrease most obviously under gas quantity of 28 NL/min,and the critical height of vortex decrease by 12mm.Compare with no argon injection,the height of drain sink decrease most obviously under gas quantity of 116 NL/min,and the height of drain sink decrease by 8mm.(2)The second blowing element has the best effect of suppressing vortex and the third blowing element has the best effect of suppressing drain sink within 3 kinds of blowing element.The slag layer thickness is greater,the critical height of vortex and the height of drain sink are lower.The influence of the slag viscosity on the critical height of vortex is not obvious,but the height of drain sink increase slightly with the increase of slag viscosity.(3)The static process of ladle is a cooling process,and the temperature of steel is decreased by 9-17? during 15 minutes.Meanwhile,the temperature stratification of the ladle is also formed because density of steel is changing with the temperature.Hotter steel fluid move upward,because they are lighter,and the colder steel stay at the bottom of ladle.Besides,the temperature gradient of the bottom of the ladle is larger than top.(4)Blowing argon around the tapping hole during teeming process can uniform the ladle temperature and avoid the uneven temperature caused by the temperature stratification.The amount of blowing is greater,the temperature of steel fluid is uniformed even faster.