Numerical Simulation Of Refining Process Of RH With Arched Snorkels

With the development of society,people have higher and higher requirements for steel quality,especially for all kinds of pure steel.All countries pay more attention to the production technology research and development of pure steel(ultra-low carbon steel,ultra-low sulfur steel,ultra-low phosphorus steel,etc.).RH refining technology is an important refining method for pure steel production.At present,the refining efficiency of traditional RH with round snorkels is limited.Increasing the inner diameter of traditional round snorkels can significantly improve the circulation flow rate,shorten the mixing time,and greatly improve the refining efficiency of RH.However,due to the limitation of the bottom area of the vacuum chamber,the increase of the inner diameter of the round snorkels is limited.In order to improve the refining eficiency of RH system,a new type of RH device with arched snorkels is adopted in this paper.The effects of gas flow rate and immersion depth on the circulation flow rate,mixing time,mass transfer uniformity in vacuum chamber,RTD curves in vacuum chamber and RTD curves in ladle of RH and traditional RH with different structures were studied by Euler-Euler method.Combined with the liquid level parameters of vacuum chamber obtained by numerical simulation,the dynamic model of RH decarbonization was established,and the influence of process factors such as gas flow rate on the decarbonization efficiency of RH was studied.The results show that:(1)Under the actual conditions,circulation flow rate of RH with arched snorkels is increased by 91%～99%and the mixing time is decreased by 25%～55%,compared with conventional one;(2)The liquid level velocity distribution and mass transfer in the vacuum chamber of with arched snorkels are more uniform than that of conventional RH;(3)The volume fraction of piston flow in RH vacuum chamber is 93.1%,which is 13.7%higher than that of traditional RH.The volume fraction of the dead zone in the ladle of RH with arched snorkels is 21.03%,which is 26%less than that of conventional RH;(4)Compared with the traditional RH,the mass transfer coefficient of liquid surface in the vacuum chamber of arched snorkels increases by 18%～23%,the decarburization speed is accelerated,the carbon content at the end of decarburization is reduced,and the decarburization time is reduced by 27%;(5)Based on the analysis of the target parameters such as circulation flow rate,mixing time,mass transfer uniformity in vacuum chamber and decarburization rate,the optimal gas flow rate of RH and traditional RH is 1.6 Nm3/min,and the optimal immersion depth is 500 mm for 150 ton ladle.