Abstract:In order to control the quality of nitrogen in the RH refining process, the theoretical equilbrium nitrogen mass fraction is analyzed by thermodynamic calculation considering the influence of liquid steel composition and RH vacuum degree, and the effect of the pressure change of circulation gas ware blowed tube to into the vacuum chamber on the equilbrium nitrogen mass fraction is also analyzed. Through the dynamics analysis, the adding and removing nitrogen process was affected by the mass transfer resistance in the gas phase, the interfacial chemical reaction resistance, and the mass transfer resistance in the liquid phase. Three kinds of nitrogen increasing pathway of RH process are proposed, and the corresponding equilbrium nitrogen mass fraction are calculated. When the nitrogen mass fraction of steel grade is greater than the equilibrium nitrogen mass fraction, two states in RH treatment process, increasing nitrogen and decreasing nitrogen, are coexistence. In the process of the variation of nitrogen concentration in liquid steel, when the rate of removing nitrogen is equal to the rate of adding nitrogen, the concentration of nitrogen in liquid steel reaches the dynamic equilibrium. For the vacuum degree of 5 kPa, the theoretical equilbrium nitrogen mass fraction in RH is 0.010 0%.