Numerical Simulation Of Hot Metal Flow And Induced Wall Shear Stress In Blast Furnace Hearth

Erosion of blast furnace hearth is closely related to the state of hot metal flow in hearth. Scour of hot metal flow is one of main reasons that increase the hearth sidewall shear stress, increase temperature of hearth sidewall and affect the life of hearth. Hot metal flow of blast furnace hearth depends largely on the status of the dead-man and the tapping operation. Therefore, in order to extend the life of blast furnace hearth, it is necessary to study the influence of relevant factors on the hot metal flow state and wall shear stress.In this work, by taking the No.3 blast furnace of Baosteel company as the research object, effects of the dead-man state and tapping operation on hearth hot metal flow are studied based on the numerical simulation. The results are as follows.Based on force analysis and calculation of the hearth dead-man, the developed model of minimum salamander depth and maximum possible dead-man floating height can be used to calculate the minimum salamander depth and the maximum dead-man floating height, which provide a theoretical basis for optimal design of salamander depth and dead-man situation in the blast furnace.Wall shear stress and the max shear stress position in furnace wall are significantly influenced by taphole length. Maintaining enough taphole length are important measures to slow down the formation of hot metal circulation and reduce the erosion of hot metal circulation.Wall shear stress is not monotonous changing with taphole angle. The position of max shear stress below taphole gradually reduced with the increase of taphole angle. Reasonable taphole is about 13°in the No.3 blast furnace of Baosteel company.Taphole diameter has obviously influenced on wall shear stress, while no obvious impact on the position of max wall shear stress.Wall shear stress and the max shear stress position are not significantly influenced by tapping with double tap-holes. Tapping with double tap-holes can decrease the shear stress as well as flushing erosion to the hearth sidewall which can help to prolong the hearth life.The decrease of the dead-man void fraction can intensify circulation of hot metal and increase shear stress of the sidewall. The change of the dead-man void fraction has no impact on the position of max shear stress. The smaller the coke particles are, the smaller resistance of hot metal flow, the bigger the shear stress.The bigger the zone of low void fraction in the center of the dead-man is, the more obvious the trend of the molten iron edge circulation along hearth side wall, the bigger the shear stress.Only when the dead-man floating height in the hearth is greater than the "critical floating height", the float of the dead-man can play an important role in slow downing hot metal circulation and reducing shear stress.A lower flow rate of hot metal and lower velocity of hot metal in BF hearth, can reduce the flushing erosion on the hearth sidewall, especially near the taphole.