Innovative visualisation technique at the electric arc furnace

The number of EAF units equipped with wall-mounted injectors and operated with closed slag door is steadily increasing. This so-called "airtight" technology provides energy savings but hinders the operator from direct process observation inside the vessel and obtaining information on the un-melted scrap volume and hence on possible skull formation at the furnace walls. In order to overcome these drawbacks, a new concept, based on mounting a camera inside an existing burner, has been proposed. This innovative technique allows a continuous monitoring of the scrap melting progress in full airtight operating conditions. The burner flame provides a clearance effect and an efficient protection of the optical window from slag splashing. A proper selection of the camera wavelength, in mid-infrared spectral range, allows a clear vision through the combustion gases and dusts prevailing in the furnace atmosphere. The first industrial application of this technique has been carried out in the PROFILARBED Esch-Belval plant, which is equipped with a 155 ton DC single shell furnace. The camera system aimed at the cold spot area, characterised by possible skull occurrence. Many heats have been monitored with this visualisation system. Topical images recorded during the melting phase are presented in this paper. In particular, scrap movement mechanisms in the burner produced cavity have been displayed in real time. Operational benefits combine the appraisal of scrap basket charging time and anticipation of abnormal melting behaviour. This development is financially supported by the European Commission.