In the mid-1980s, foreign manufacturers developed DC electric arc furnace steelmaking technology. Compared with AC arc furnaces, DC furnaces offer several practical advantages. Let’s take a look at them:
- Electrode consumption is reduced by more than 50%
- Energy consumption per ton of steel decreases by 5–10%
- Furnace lining service life increases by more than 30%
- More uniform molten pool temperature and more stable tapping temperature
- Noise reduced by approximately 10 dB
- Arc flicker is reduced by 50%, resulting in lower interference with the electrical grid. When using a DC furnace, the required grid capacity is only half of that needed for an AC furnace.
Structurally, the main difference between DC and AC arc furnaces is the addition of an AC-to-DC rectifier system. The number of graphite electrodes on the furnace roof is reduced from three to one, and a bottom electrode is added inside the furnace.
Although the initial infrastructure investment for a DC arc furnace is about 20% higher, the payback period is significantly shorter. If existing AC arc furnace systems in China were upgraded to DC furnaces, the investment could be recovered in about six months.