IMPROVING THE RESISTANCE OF GRAPHITIZED ELECTRODEBY ORGANISING ARGON BLOWING THROUGH THE HOLLOW ELECTRODE

Abstract

In consequence of the fact that the main source of heat energy in the ladle furnace is the electric arc between
the liquid metal and the electrode candle, there is a significant consumption of graphitized electrodes. Verification of the data confirmed the dependence of electrode mass reduction on the temperature of the contact medium. As a solution to the problem of high temperatures, the supply of inert gas (argon) through the axial opening of the electrode was proposed. From
the developed one-dimensional thermophysical model we determined the necessary and sufficient diameter of the axial channel at a given temperature of argon at the outlet of the electrode 1100 °С. The value of 700 n.l/min was the preferred flow rate of argon, and the diameter of the axial channel is within the range of 45–53 mm. To verify the obtained results and to study the temperature distribution in the electrode, the process was simulated in the ANSYS software environment. The
temperature change occurred only in the electrode body, on the surface the temperature distribution changed insignificantly. The spot of high temperatures (3000–4000 °C) at argon supply shifted to the electrode axis and does not go from the end surface to the side one. To verify the obtained theoretical data, two electrode candles with diameters of axial holes of 20 and 50 mm were prepared. The argon supply was 340 n.l/min and 700 n.l/min, respectively. To form a comparative basis, the volt-ampere characteristics were measured at different modes of metal finishing on standard and hollow electrodes with different inert gas flow rates. In the course of experimental melting it was possible to reveal a decrease in amplitude and
fluctuations of voltage and current when using electrodes with an axial hole. As a result, the consumption of electrodes decreased by 17%, and the energy consumption of the installation decreased by 5.5%.