NUMERICAL MODELING AND DYNAMIC BEHAVIOR PREDICTION OF THE AC ELECTRIC ARC FURNACE STRUCTURES DURING THE SCRAP MELTING PROCESS

Prediction of the dynamic behaviour of the mast / arm / electrode system of an AC Electric Arc Furnace (EAF) is a rather complex issue because of several phenomena occurring during the melting process. Experience shows that significant vibrations can be observed during EAF operations whose amplitude are dependent on the coupling between mast movement and electromagnetic forces. Control strategy, based on impedance or current, is performed by means of an hydraulic actuator, which sets the vertical position of the mast column, supporting the electrodes. Magnetic fields, produced by each phase, apply some electromechanical actions among electrodes and arms that produce additional vibrations. A fully coupled model of the EAF system was therefore developed in order to get insights of such phenomena and to provide support to an optimal design of structures. Structures were interpreted as flexible bodies and introduced into a Multi-body dynamics code as well as models of currents and electromechanical actions. Several loading conditions and layouts were compared to detect critical issues of the EAF design and suitably set the related parameters. Some experimental confirmations were found, although a complete validation looks rather difficult because of some severe limitations in accessibility of the system during the melting process.