Experimental and numerical investigation of the electrothermal behavior of self-baking electrodes under AC and DC operation in submerged arc furnaces

The electrothermal behavior of self-baking electrodes governs electrode baking, furnace stability, and energy efficiency in submerged arc furnaces (SAFs). To clarify the differences in the electrothermal behavior of alternating current (AC) and direct current (DC) self-baking electrodes, this work combines industrial temperature measurements with numerical simulations. Temperatures inside self-baking electrodes in two industrial SAFs were measured using embedded K-type thermocouples to characterize the baking process and validate the electrothermal model. The model analyzed the distributions of current density, Joule heating, and temperature under AC and DC operation. The measurements characterize the baking processes of the two industrial electrodes, with a greater paste softening height observed in the AC electrode than in the DC electrode. The simulations show that, at the same root mean square (RMS) current of 100 kA, AC operation induces pronounced casing eddy currents and the associated Joule heating, whereas DC operation produces a more uniform current distribution and a higher electrode-core temperature from the contact clamps region to the electrode bottom. These findings reveal the distinct electrothermal behavior of AC and DC self-baking electrodes, providing theoretical guidance for power supply selection and stable SAF operation.