Development Of Process Models For LF Steel Refining

The present study was concerned with process models for a steel ladle furnace.Based on a hybrid modelling of theoretical analysis and practice,several models were built for temperature prediction,alloying,material and heat balance and composition prediction with the help of VC 6.0.The main contents can be summarized as follows:(1)The material and heat balance model was established base on the mass and energy conservation for the liquid steel-ladle-slag system.(2)The temperatu.re prediction model was built with the help of relationship between liquid steel temperature and time based on the heat analysis.(3)The mechanism of component change in the LF steel refining was investigated.The effects of kinetic factors on liquid steel composition variation were analyzed based on the thermodynamic calculation.A relational expression for liquid steel bulk concentration and slag bulk concentration was derived as a function of time.And the mathematical model for composition prediction was established.(4)The main parameters were calculated in the composition prediction model.The activity coefficients of component in liquid steel were calculated by the Wagner's formula.Also,the activity coefficients of component in slag were calculated by the model of completely ionic solution.A hybrid modeling method was used to determine the product of mass transfer coefficient(ki)in liquid steel and area(A)of reaction interface between metal and slag.The result of Aki was Qg/30.4.(5)Deviation of the results in the models was verified by the data in practice.The results showed that the final temperature error was less than 6? exception of 12? in F661004735 heat.Final oxygen content error was 6X 10-6 and an exception error was 12 X 10"6 in F51004690 heat.Furthemore,final sulfur content error was less than 6X 10-6.Six forecast values in refining process were verified by the observed values.The results showed that the predicted values were in good agreement with the observed values.