Control by camera of the EAF operations in airtight conditions : final report

A growing number of EAFs are equipped with wall-mounted injectors and operate with the slag-door closed. In order to observe the scrap-melting process under these conditions, CRM has developed a camera-based technology to monitor the inside of the furnace during meltdown. The camera system is able to see through combustion gases by selecting its wavelength to be in the mid-infrared spectral band. The first industrial application of this camera technology was carried out at the ArcelorMittal Esch-Belval plant, which is equipped with a DC furnace. The endoscopic system was mounted inside a dedicated burner in the furnace sidewall. The burner flame provided a clearance area and helped to protect the optical window from slag/metal splash. Many heats were monitored with this system, showing scrap-drop events and the scrap-melting phase in real time. The camera system was also installed in the roof of Corus Engineering Steel's AC 'N' furnace. A holder was especially designed to prevent slag and metal splash from adhering to the tip of the endoscope by blowing high volumes of air through a De-Laval nozzle. The image quality at the beginning and end of a melt was generally very good. However, after several minutes of arcing, generation of high dust density had a significantly deleterious effect on the resolution of the images. Towards the end of the melting period, the view cleared again and excellent quality images were seen of foaming slag behaviour. The tapping process could be plainly seen as well as the hot heel before next scrap charging.