PREHEATING OF A STEEL LADLE VIA A DC PLASMA TORCH: PRELIMINARY RESULTS ON ECOLOGICAL IMPACTS IN THE COMPARISON WITH A NATURAL GAS BURNER

This paper is located in the general context of European industrial research aimed at the de-carbonization of energy intensive productive processes, in particular in the sector of secondary steelmaking. It synthesizes the main ecological findings of the project “PlasmaPilot” (acronym for “Flexible Ladle Preheating Procedures using Plasma Heated Refractory”), financed by the European Commission and ended in December 2023, whose goal has concerned investigating on the opportunity of substituting the current and traditional equipment used for steel ladle preheating, based on gas burners (using fossil origin gases, mostly NG and, to a limited extent, LPG), with an electrically supplied plasma torch. In steelmaking, ladles are used to transport liquid steel from tapping at BOF or EAF to teeming at caster. Ladle preheating is a crucial procedure undertaken on a cyclic basis, each time a ladle, after a maintenance stop or after refractory re-lining, has to return to operational service and be filled with hot liquid steel. The preheating procedure is finalized to minimize thermal shock and damage to the refractory lining and to reduce the temperature drop of the liquid steel. A plasma preheater, in particular in the form of a non-transferred arc system, has been selected as the most promising solution to fulfil this technological requirement because of higher attainable temperatures and, compared to a gas burner, potential improvements in flexibility, process control and safety. Furthermore, a potential direct ecological advantage relies on the electrification itself, which avoids the combustion of fossil fuel gases. Results show that benefits could be achieved for the Climate Change impact category, depending on the electricity mix composition considered, whereas, for other impact categories, the situation can be different and evaluations based on more updated data, regarding the NG supply chain in particular, are needed.