Improved Electrical Control of Ladle–Furnace Units by Means of Arc-Current Harmonics

Resumo

Abstract—The influence of the intensity of argon injection in a two-position ladle–furnace unit on its electrical parameters is considered. Waves and surges formed at the surface of the liquid metal under the action of intense injection lead to periodic short-circuiting in the phases closest to the nonsteady zone. In addition, the deterioration in slag conditions lowers the thermal efficiency of the arc closest to the phase meniscus. To minimize these effects, improved electrical control is proposed, with adaptation to the changing arc-combustion conditions. To that end, the harmonic composition of the arc currents is analyzed. The new control algorithm decreases the power consumption of existing ladle–furnace units, with no loss in heating rate of the liquid steel.