Nitrogen control during production of stainless steel

Purpose and goal

The aim of the project was to develop a model for nitrogen content in stainless steel that improves the prediction of the charges that today are not at the desired nitrogen content. The project has developed such a model, TimeAOD3. The model is dynamic and is based on thermodynamic databases (from Thermo-Calc). CFD calculations have been used for fundamental questions such as the pressure at which the reactions take place, which together with information from the literature has been implemented in the model. The model has also been validated against plant trials in the project.

Expected results and effects

A time-dependent AOD model has been developed based on thermodynamic equilibrium calculations to predict the content of dissolved nitrogen and other metal / slag compositions. The model was later tested on site with suggestions for blowing method during the reduction step. A licentiate degree is planned for Q2-22, the candidate has been employed by the Swedish steel industry. A PhD degree is planned for Q4-22, this PhD student is an industrial PhD student who is already working towards the Swedish steel industry. A BSc degree project with two future engineers has also been delivered.

Planned approach and implementation

The project was carried out largely according to the project plan, where the model for nitrogen prediction was gradually improved through numerical calculations and uncertainty analysis as well as measurements in operation. Finally, it was validated with a series of measurements in participating works. The project has had about 4 meetings per year and has been continuously documented in Jernkontoret´s PIA portal. The pandemic affected the ability to perform measurements in operation, which extended the project by about six months.