Numerical Simulation Of Transport Process Of Tracer In Water Model Of Single Snorkel Refining Furnace

The improvement of mixing conditions in vacuum refining unit plays an important role in enhancing the purity and decarbonization of molten steel.Water model has been used to investigate the effects of various factors on the mixing time of molten steel.However,the effect of injection of tracer on the distribution of flow field was somehow ignored.Therefore,based on the prototype of 130 ton single nozzle refining furnace(SSRF)in industrial production,STAR-CCM+ software is used to make an in-depth study on the distribution of flow field,transfer process of tracer and mixing phenomenon in the numerical model established with the geometric ratio of 1:5.Thetransport process of passive scalar,KCl solution tracer and pure water tracer(with the same properties as liquid phase in water model)in water model of Single-Snorkel Refining Furnace,and the effects of density and dosages of tracer on flow field are studied.The results are summarized as follows:(1)In the transport process of tracer in the water model of SSRF consists of one main circulation stream and two side circulation streams.A main circulation stream: the injected tracer at the top of the vacuum chamber diffuses to the side wall of the vacuum chamber and merges to flow downwards along the snorkel to the ladle.Afterwards,owing to the effect of gas column,the tracer flows upwards to the snorkel and the vacuum chamber again.Two side circulation streams: a portion of tracer at the bottom of the ladle flows upwards to the gap between the snorkel and the ladle at the right side(nozzle-located).Afterwards,the tracers flow either clockwise or anti-clockwise(top view)near the top surface of water in the ladle and disperse to the gap between the snorkel and the ladle at the left side.Finally,the tracers diffuse to the bottom of the ladle again.(2)Compared with pure water tracer,150 m L KCl solution tracer flows downwards at a higher pace from the vacuum chamber to the bottom of the ladle and later disperses rapidly from the bottom to the nozzle-located side wall of the ladle.However,compared with 20 and150 m L KCl solution tracer,when the tracer inlet is located at the eccentric side of the top of the vacuum chamber,150 m L KCl tracer flows downwards at a higher pace from the vacuum chamber to the bottom of the ladle and later disperses rapidly from the bottom to the nozzle-located side wall of the ladle;when the tracer inlet is located at the away from the eccentric side of the top of the vacuum chamber,the transfer process of20 and150 m L KCl solution tracer flow to the eccentric sidewall of the ladle at thesame time.Besides,due to theexist of “dead zone”at the bottom of the nozzle-located side wall of the ladle,the difference of the transport process among the tracers in the subsequent mixing process is negligible.(3)Compared with the scheme between the tracer inlet: left and right sides of the top of the vacuum chamber,the former is more concentrated near the top of the vacuum chamber and flows to the bottom of the ladle and diffuses uniformly around.At the eccentric side wall of the bottom of the ladle,the tracer concentration of the latter is higher,which is more affected by the dead zone,and the peak value of the corresponding concentration-time curve is higher.The time for the tracer to reach the top of the ladle in the left adding scheme is earlier than that in the right adding scheme,and its mass fraction is mainly concentrated away from the eccentric side of the top of the ladle,and then the tracer directly transfers downward to the away from the eccentric side of the bottom of the ladle,where the increase rate of the tracer concentration-time curve is faster.