DC submerged arc furnace is superior to AC arc in stability and single direction, which has great benefits for heat transfer in metallurgical processes. Theoretical analysis indicates that replacing AC current with DC current is a significant technological innovation measure. Due to the absence of zero crossing of DC current, the stability of the arc is improved, and the interference to the power grid is reduced accordingly. The method of using direct current to smelt metal in a direct current submerged arc furnace is basically the same as that of an alternating current arc furnace.
However, due to the high anode heat on the charging side, the electric heating efficiency of the DC arc is high. Using a controllable thyristor static converter as the power supply for the DC submerged arc furnace, the AC power supply can be converted into DC. Practices of the DC submerged arc furnace ferroalloys production confirmed the advantages of the DC submerged arc furnace process including energy saving and other economic benefits.Compared with AC furnace, except for yield is the same, specific energy reduces.
The structure of DC submerged arc furnace is basically similar to that of AC submerged arc furnace. The main electrical equipment includes rectifier transformer, rectifier cabinet, high and low voltage electrical equipment and electric control system. The main mechanical equipment includes single-phase self baking electrodes or graphite electrodes, electrode holders, electrode lifting structures and electrode hold and release devices, semi enclosed low smoke hoods, conductive furnace bodies, hydraulic systems, water cooling systems, feeding devices, and smoke exhaust systems.
The key feature of the DC submerged arc furnace is its conductive furnace bottom and anode. These components serve as both the melting crucible and the input terminal for the DC power supply.
One of the standout features of the DC submerged arc furnaces is their ability to reduce electrode consumption by 40-50% compared to AC systems.
The DC submerged arc furnace minimizes noise intensity, decreasing it by 7-13 dB, which contributes to creating a safer working environment.
Another advantage of the DC submerged arc furnace is the improved power factor, which can rise to an impressive 0.93-0.94, further optimizing energy use.
Furthermore, productivity sees a substantial boost with the implementation of the DC submerged arc furnace, increasing by 10-15%.
| Item | Typical Value / Range | Remarks |
| Furnace Type | Fixed Hearth / Rotating Hearth (Closed or Semi-Closed) | For ore reduction smelting |
| Rated Power | 12.5 MVA ~ 81 MVA+ | Transformer rating |
| Rated Capacity | 10 T ~ 150 T+ (per batch) | Depends on product (e.g., Ferrosilicon) |
| Furnace Shell Diameter | 6,000 mm ~ 9,200 mm+ | Scales with power rating |
| Furnace Shell Height | 4,000 mm ~ 5,000 mm+ | Includes freeboard for gas |
| Electrode Type | Self-baking Soderberg / Graphite | Top Cathode(s) |
| Number of Electrodes | 1 (Standard DC) / 4 / 6 | Multi-electrode for very large capacities |
| Electrode Diameter | 800 mm ~ 1,400 mm | For large-scale SAFs |
| DC Input Voltage | 800 V ~ 1,500 V | Secondary voltage after rectification |
| Total Rated Current | 20 kA ~ 125 kA | High current, low voltage characteristic |
| Electrode Consumption | 0.4 ~ 1.0 kg/t (product) | Significantly lower than AC SAF |
| Power Consumption | 2,800 ~ 8,500 kWh/t | Varies greatly by product (e.g., Si vs FeCr) |
| Smelting Temperature | 1,800 °C ~ 2,300 °C | Inside the submerged arc zone |
| Furnace Bottom Type | Conductive Hearth Anode (Steel + Carbon bricks) | Current return path |
| Cooling Water Pressure | 0.4 ~ 0.6 MPa | For electrodes, busbars, and hood |
| Tapping Type | Taphole (2 or 3 positions) | Opened mechanically or hydraulically |
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