Research On Dynamic Conditions Of Full Campaign Life And Furnace Lining Evolution During The 300t Converter Steelmaking Process

With the increasing demand for high-quality steel,the converter steelmaking technology and smelting equipment have been greatly developed.The modern converter steelmaking process has gradually developed from the traditional converter smelting function to a single function,that is,it only performs a single function.The core of this process is to use two converters(dephosphorization converter and decarburization converter)to perform dephosphorization and desulfurization of molten iron.The decarburization operation is beneficial to shorten the smelting cycle,improve the quality of molten steel,and reduce the consumption of metal materials and energy consumption.The main task of the decarburization converter is to decarburize and raise the temperature of the semi-steel produced by the dephosphorization converter Therefore,the temperature of the molten pool is fast,the carbon-oxygen reaction is violent,and the corrosion rate of the furnace lining is faster,which ultimately leads to the growth of the furnace age.,The furnace type of the decarburization converter changes greatly,and the gas supply capacity of the bottom blowing element is unstable.Based on this,this article combines the actual thickness measurement data to study the changes in the flow characteristics of the molten pool at different stages of the furnace campaign,and proposes a non-uniform bottom blowing gas supply mode;at the same time,the current research process of supersonic oxygen jets has not been considered The influence of furnace gas and its composition on the characteristics of supersonic jets.Therefore,this article focuses on the study of the characteristics of supersonic jets under high temperature and variable atmosphere conditions.Based on numerical simulation and cold-state physical simulation research methods,this paper systematically studies the effects of supersonic jet characteristics,molten pool flow characteristics in different furnace stages,and non-uniform bottom blowing gas supply mode on the dynamic conditions of the molten pool.A compressible,non-isothermal and three-dimensional full-scale oxygen jet flow mathematical model was established,the flow characteristics of supersonic oxygen jet was studied under high temperature and variable atmosphere conditions,and the radial and axial dynamic characteristics distribution of the jet was analyzed.The results show that when the oxygen jet flows through the high temperature furnace gas and acts on the surface of molten pool,the oxygen will undergo a combustion reaction with the combustible gas in the furnace gas.As the reaction occurs,the velocity distribution,density distribution,and dynamic pressure distribution of the supersonic jet will all change,and the radial distribution of jet dynamics parameters conforms to the "Gaussian distribution".With the increase of the carbon monoxide volume fraction in the furnace gas,the radial expansion rate of the jet boundary increases,the vorticity at the jet boundary layer increases,and the area of the high-speed zone increases.In the process of studying the flow characteristics of the pure bottom-blowing molten pool of a 300t converter,a cold physics experiment platform with a similar ratio of 1/7 was established;a three-dimensional full-scale,two-phase flow mathematical model was established.During the pure bottom blowing physical simulation experiment,a systematic study was carried out on the number of bottom blowing components,the position of bottom blowing components,and the bottom blowing layout pattern.The results showed that:There is an exponential relationship botween the bottom blowing flow rate t=49.74+99.06×exp(-q?/0.30),and the four bottom blowing elements arranged at the 0.45D position have the strongest stirring ability for the molten pool.In the process of pure bottom blowing numerical simulation,the velocity distribution in the molten pool and the characteristics of molten steel flow are analyzed.The results show that the flow characteristics and velocity distribution of the molten pool are not only related to the position of the bottom blowing element,but also related to the bottom blowing stream.There is a connection with the energy available;the locations with serious corrosion of the furnace lining are mainly concentrated around the bottom blowing element at the bottom of the furnace and near the molten steel level;during the study of the non-uniform bottom blowing gas supply mode,it is found that when the gas supply capacity of a bottom blowing element is weakened,The fluidity of the molten pool becomes worse,and the dynamic conditions of the molten pool can be improved to a certain extent by adjusting the air supply capacity of the bottom blowing element at the adjacent and diagonal positions.Establish the energy transfer model between the bottom blowing stream and the molten steel.The relationship is W1=(1-?)'W0+1-(1-?)1/?·F·h.In the process of studying the flow characteristics of the combined blowing bath of a 300t converter,a cold physics experiment platform with a similar ratio of 1/7 was established;a three-dimensional full-scale,"gas-slag-gold" three-phase flow mathematical model was established.Study the characteristic phenomena of the interaction between gas stream and molten pool under different combined blowing schemes and different combined blowing process conditions,and explore the changes in flow characteristics of the molten pool.The results show that when the combined blowing flow rate increases,the foaming degree of the molten metal in the furnace increases,the impact depth and impact area increase,and the corrosion of the furnace lining increases.Among them,the vicinity of the bottom blowing element,the position of the slag line and the lining of the splashing foamed slag The corrosion at the location is more serious;with the increase of furnace age,the dynamic conditions of molten steel gradually deteriorate and the corrosion of the furnace lining gradually increases,and the numerical simulation results of furnace lining erosion are in good agreement with the actual production thickness measurement results.Based on the above theoretical analysis and laboratory research,the 300t decarburization converter industrial test was carried out.The results show that in the actual converter steelmaking process,the blowing is stable,the back-drying period is shortened,the number of "splashing" is greatly reduced,the smelting cycle and the blowing time are shortened by 6.92%and 7.64%respectively;the control level of the smelting end point is improved,specifically:The average carbon and oxygen concentration product of the whole service is 0.00098%,and the total iron content of the final slag is 17.41%;when the repairing process is regularly applied to actual production,there is an obvious linear relationship between the bottom residual thickness and the furnace age y=1195.88-0.5274x(300?x?500)and y=1055.92-0.1545x(500?x<4000).