Simulation Analysis Of Intervention Measures Of Variable Operating Conditions Under Erosion State Of Blast Furnace Hearth

The blast furnace is a high temperature and airtight reaction vessel.The service life of the hearth is a key factor restricting the life of the blast furnace.The blast furnace hearth lining is directly contacted with hot metal.Under the action of hot metal scouring and high temperature thermal stress,the erosion of blast furnace hearth is inevitable.The most direct impact of blast furnace hearth erosion is to cause hearth damage,more serious harm is to cause hearth burning through.In order to ensure the safety of the hearth tapping process and prolong the life of the hearth,it is of great significance to study the erosion stopped condition of blast furnace hearth and to carry out simulation analysis of different interventions after reaching this condition.Because of the continuous erosion characteristics of the hearth lining of blast furnace,erosion will not stop automatically.When the hearth lining is reduced to a certain thickness,the erosion can be stopped or the hearth erosion can be alleviated by changing the operating conditions.Based on the strength theory,a calculation method of safety thickness is proposed.The circumferential stress on the hot surface of the hearth lining is compressive stress.Because the lining material is brittle material,when the compressive stress exceeds its strength limit,the lining will be damaged.When the thickness of lining is reduced to make the circumferential stress equal to the strength limit of lining,the safe thickness of lining is determined.The process of continuous erosion of blast furnace hearth can be regarded as the process of removing material from hearth lining.ANSYS life and death unit technology is used to simulate the process of hearth erosion.The "mushroom" erosion often occurs in the inner lining of blast furnace hearth in service.In this paper,the calculation model of the whole "round corner" erosion and the local"mushroom" erosion under the erosion condition is established,and the simulation of the hearth tapping under the interference condition is studied.The common interventions to change operating conditions are blocking tuyere,adding titanium ore,controlling production and strengthening cooling.The simulation of different interventions is realized by changing hearth parameters.Usually,the 1150 C isotherm of hearth shaft section is used to estimate the erosion boundary of the lining.The heat transfer of molten iron to the lining is reflected by the heat transfer coefficient.The effect of the intervention is obtained by comparing the erosion radius and heat transfer coefficient under different intervention conditions.Design-Expert software was used to analyze the experimental design and model selection of the erosion radius of hearth,the velocity and heat transfer coefficient of molten iron at key points.The regression equation of erosion radius and velocity of molten iron under the interaction of different parameters was obtained.The sensitivity of intervention parameters was studied by response surface methodology.