Dynamic control of EAF burners and injectors for carbon and oxygen for improved and reproducible furnace operation and slag foaming

The objective of the project was the development of techniques to improve the control of the energy input by natural gas burners and of the wall mounted oxygen and carbon injectors of the electric arc furnace (EAF). Process data acquisition and measurement systems for foamy slag detection were implemented at the EAFs of ArcelorMittal Belval (DC), Sidenor (AC) and GMH (DC). Plant trials with different carbon and oxygen injector configurations and operation regimes were evaluated to derive control strategies for carbon and oxygen injectors regarding foamy slag control and adjustment of final carbon and oxygen content of the melt. A laser-based distance sensor was developed, tested and installed inside a natural gas burner, to detect the distance to the actual scrap load in front of the burner during scrap preheating. A tentative control algorithm for the burner operation was derived from industrial trials at the ArcelorMittal Belval EAF. A comparison with the water-cooled panel overheating proved the ability of the sensor to predict the blow-back phenomenon and thus to avoid burner damage. Control concepts for carbon and oxygen injection were developed on the basis of carbon and oxygen content measurements, signals for foamy slag detection, off-gas analysis values and dynamic model calculations. The online implementation of an automatic injector control at the Sidenor EAF led to a reduction of the main EAF parameters, like power-on and power-off times, and electrical energy consumption. Furthermore, the foamy slag performance was improved. Results of plant trials showed that similar results can be expected when dynamic control concepts are implemented online at the EAFs of ArcelorMittal Belval and GMH.