Study On The Dynamic Behavior Of Scrap Melting In Converter Molten Pool

Scrap steel is an indispensable and important steelmaking raw materials and high-quality renewable resource in the steel industry.More scrap steel used in the steelmaking process can reduce the generation of waste and the consumption of metallurgical resources.Therefore,exploring the melting mechanism of scrap steel in converter molten pool,the influence law of different factors,and the phenomenon of heat and mass transfer are helpful to analyze the melting behavior of scrap steel,which is of great significance to increase the scrap ratio of the converter steelmaking process.In this thesis,the mechanism and behavior of scrap melting process were explored by numerical simulation and water model experiment,and the influence of bottom blowing parameters and scrap parameters on the melting behavior of scrap under different top blowing jet conditions and top and bottom re-blowing conditions were studied,so as to provide theoretical guidance for guiding converter scrap addition and promoting scrap melting.The main conclusions are as follows:(1)The numerical simulation results show that the scrap undergoes the formation of solidification layer and remelting stage during the melting process.With the increase of the preheating temperature of scrap,the temperature of molten steel and the decrease of size,the formation and remelting time of the solidification layer on the surface of scrap steel decreases,the central heating rate of scrap increases,the heat transfer rate of molten steel to scrap accelerate,and the complete melting time is shortened.When the preheating temperature of scrap is 1073 K,which is 58% shorter than the melting time without preheating.The instant heat transfer coefficient of convection between scrap and molten under different conditions is 90～720 W/(m2·K).(2)The results of the water model experiment show that under the condition of top-blowing jet,the six-hole staggered oxygen lance jet has the most significant cooling rate on the solution pool compared to the traditional five-hole oxygen lance,five-hole swirl oxygen lance and the traditional six-hole oxygen lance jet,and the complete melting time of the ice is the shortest.The ice melting effect is the best when the oxygen lance position is 35 de and the top-blowing flow rate is 80 Nm3/h.For the 260 t converter,the best process operation scheme for the stirring effect of the molten pool is: oxygen lance position 1950 mm,top-blowing flow rate 51000 Nm3/h,six-hole staggered oxygen lance.The Heat transfer coefficient between water and ice is 800～2050 W/(m2·K).(3)Under the condition of top and bottom re-blowing,appropriately increasing the bottom blowing flow,increasing the ice ratio,increasing the specific surface area of the ice,reducing the size of the ice and adopting the asymmetric bottom blowing element arrangement can effectively reduce the melting time of the ice.When the bottom blowing flow rate increases from 0.20 m3/h to 0.50 m3/h,the ice melting time is shortened by 15.5%,and the heat transfer coefficient between ice and water increases from 2600 W/(m2·K)to 4250 W/(m2·K).The diameter of the ice increases from 5 cm to 12 cm,the melting time is increased by 112.5%,and the heat transfer coefficient reduces from 3900 W/(m2·K)to 2700 W/(m2·K).The specific surface area of the ice increases by 43%,its melting time is shortened by 31.8%,and the heat transfer coefficient increases from 2000 W/(m2·K)to 4000 W/(m2·K)。...