Electric arc furnace
Process Description
About 30% of the world's steel is produced in electric arc furnaces. The smelting of scrap and sponge iron, with or without the accompaniment of pig iron takes place in steel works by means of electric arc furnaces. Significant developments have taken place over recent decades in transformers, panels, furnace geometry, foam slag technology, automation, electrode regulation, hydraulics, and the use of oxygen, which have significantly improved the economic efficiency of the process.
An EAF consists of the hearth (refractory bricked lower part of the furnace vessel with tap hole), water-cooled panels, the lid with the electrodes, and the exhaust port. The oven is loaded with baskets from above by swivelling the lid and electrodes to the side. After the lid is closed and the electrodes retracted, the melting process begins. Electrical energy is converted into thermal energy by an electric arc between the electrode and the feedstock. The arc generates temperatures up to 3500°C and heats the molten steel up to 1800°C. Here, the converter is replaced by oxygen for refining.
Example of an electric arc furnace
The use of oxyfuel technology supports the process by replacing electrical energy with chemical combustion energy. At the end of the melting phase, oxygen is injected for refining.
Advantages:
- Savings in electrical energy
- Minimises batch times (tap to tap)
- Shorter power-on times
- Savings in electrode consumption
- Improvements in foam slag technology
Application example:
|
Operating data |
|
Minimum |
Maximum |
|
Loading weight |
[t] |
20 |
200 |
|
Tapping weight |
[t] |
17,6 |
162 |
|
Output |
[%] |
78 |
94 |
|
Power on time |
[min] |
15 |
160 |
|
Power off time |
[min] |
6 |
46 |
|
Tap to tap time |
[min] |
35 |
203 |
|
Electrical energy |
[kWh/t] |
318 |
525 |
|
Oxygen combustion |
[Nm³/t] |
18 |
50 |
|
Natural gas consumption |
[Nm³/t] |
0 |
13 |
|
Total carbon consumption |
[kg/t] |
4 |
31 |
|
FeO in slag |
[%] |
28 |
46 |
|
Electrode combustion |
[kg/t] |
1 |
3,1 |
|
Tapping temperature |
[°C] |
1600 |
1720 |
Energy consumption refers to tapping weight
Gas Application
- Oxygen lances
- Coherent jet system
Messer SOlution
In addition to the gases required by the process, with a cooperation partner Messer offers a coherent jet system of a modular design, consisting of an oxyfuel burner system with integrated supersonic oxygen injection and pneumatic coal dust feed and regulation and control of oxygen, fuel and carbon, also including the related automation with software.
Oxyfuel burner system with integrated supersonic oxygen injection
The Messer experts have extensive know-how on the relevant process sequences and are able to adapt the system exactly to your requirements.