Save the date: 31.8. at 9:10 am
Our head of research Dr. Matti Aula will present in ESTAD2021 31.8. at 9:10 am with the topic “Decreasing EAF electrode wear in stainless steelmaking by controlling the arc exposure”
Below is the abstract of the presentation:
Dr. Matti Aula
Electrode wear contributes significantly to electric arc furnace (EAF) operating costs. The electrode wear occurs due to sidewall oxidation and electrode tip sublimation. The electrode tip sublimation is linked to the electric arc current, which means that the electrode wear can be decreased by increasing the voltage to current ratio. The drawback of utilizing higher arc voltage is that the arc is longer, which means that if the scrap in the electrode hot spot is fully molten and the EAF sides are exposed, energy losses to the sidewalls and refractory wear increase. This is especially problematic in stainless steel production where submerging the arc with foaming slag is difficult. Another aspect of increasing voltage to current ratios is that the arc power is somewhat reduced.
Luxmet Ltd utilizes optical fiber technology to measure the heat transfer to EAF sides dynamically. The light emitted from the EAF hot spots can be collected with optical fibers installed on the EAF roof and analyzed remotely. As the scrap on the hot spots melts, the heat transfer to the sides increases, resulting in a higher intensity of optical emissions. The refractory wear at electrode hot spots can be prevented if the higher voltage to current ratio is used when the scrap in electrode hot spot areas is not fully molten. As the scrap near the electrode hot spots melts, the arc length can be shortened by decreasing arc voltage.
The control practice for decreasing the electrode wear was tested at an industrial EAF. The control scheme was utilized when the productivity allowed a small decrease in tap-to-tap-time. The control system was used during the high voltage steps in fully automatic mode without operator actions. The results from the trials show that the electrode wear can be significantly reduced with also decreased consumption of gunning mass.
Bowman B & Kruger K, “Arc Furnace Physics”, Verlag Stahleisen, 2009.
Aula M. “Optical emission from electric arc furnaces”, [Doctoral Thesis], University of Oulu, 2016.