Lining protection for arc furnace used in steel mfg. - comprises measuring its electric resistance during melting down of solid charge

摘要

During the melting of a solid charge, the electric resistance is measured between at least two points on the furnace lining above the melt and, when a sudden, persistent drop in resistance occurs, the power is reduced to the value employed after melting down. The A.C. resistance is pref. measured, esp. via the impedance w.r.t. magnitude and phase, taking the dialectric properties of the lining into account. The pref. device uses two electrodes in contact with the lining, fed by an A.C. generator with adjustable frequency, the circuit contg. a band-pass filter, A.C. voltmeter and a controller which adjusts the power supply to the arc. Method prevents the lining from being directly exposed to the higher arc temp. used for melting down, esp. in large arc furnaces with high power ratings, and increases the lining life.