Mathematical Model for Decarburization Process in RH Refining Process

Abstract

A three-dimensional mathematical model for natural decarburization process of ultra-low carbon Al killed steel during RH refining has been established. The decarburization behavior in RH degasser was discussed on the basis of a comparison between simulation data and the actual plant trials ones. The effects of the different initial carbon content, initial oxygen content, the lift gas rate and inside diameter on decarburization were investigated. The results showed that when the dissolved oxygen concentration was 0.08% in the molten steel, the flow rate of gas injected through the up-leg was 120 Nm³/h, the inside diameter of up and down-leg was 650 mm, under these conditions, the initial carbon content was 0.03%, 0.023% and 0.015%, respectively, after about 25 minute, the average carbon content in molten steel was 0.011%, 0.01% and 0.0008%. The final dissolved carbon content is related to the initial dissolved oxygen content in molten steel. The average carbon concentration and the decarburization rate of the molten steel will decrease with the increasing of the initial dissolved oxygen content. The effects of different inside diameter of up and down-leg were also compared, it shows that the increasing of the diameter of up/down-leg will promote decarburization effectively, which can increase the circulation flow rate and promote the reaction rate.