Four - Electrode Large DC Submerged Arc Furnace

1. Basic Structure and Working Principle

Core Components

• Electrode System: Four vertically inserted graphite or self - baking electrodes arranged in a rectangle (common square layout), with diameters ranging from 800 - 1200mm for large - scale furnaces.
• Power Supply System: Composed of a rectifier transformer, thyristor rectifier cabinet, DC reactor, and short - net. It converts AC power to DC power to supply the electrodes, and the DC reactor suppresses current surges and stabilizes the arc.
• Furnace Body: It includes a steel shell, a refractory lining (high - alumina bricks + carbon ramming mass), and a conductive furnace bottom (graphite - carbon brick anode + copper conductive layer), which can withstand high temperatures of 1800 - 2200℃ and strong electrical conductivity.
• Auxiliary Systems: These cover a cooling water system, a dust removal system, an automatic feeding system, and a PLC control system for real - time monitoring and adjustment of smelting parameters.

Working Principle

2. Key Technical Parameters (Typical Large - Scale Model: 40 - 63MVA)

3. Core Advantages vs. Traditional Furnaces

4. Application Scenarios

1. Ferroalloy Production: Used for smelting high - carbon ferrochrome, ferrosilicon, silicomanganese, and ferrotungsten, which is suitable for large - scale and high - quality production requirements.
2. Industrial Silicon Smelting: It can handle high - purity silica, with a silicon purity of up to 99.5% - 99.9% and a high smelting rate.
3. Calcium Carbide Manufacturing: The stable high - temperature environment ensures a calcium carbide content of ≥80% and reduces energy consumption by 8% - 10% compared to AC furnaces.
4. Rare Metal Recovery: It is applicable to the reduction and smelting of nickel - cobalt ore and tantalum - niobium ore, with strong adaptability to complex raw materials.

5. Typical Configuration and Operation Notes

Configuration

• Electrode Layout: A square layout with a center - to - center distance of 2.5 - 4.0m for electrodes, ensuring uniform current distribution.
• Power Supply Control: Adopt dual - rectifier cabinet parallel operation (20 - 30MVA per cabinet) to achieve independent current adjustment for each electrode and arc length automatic control.
• Conductive Furnace Bottom: A multi - zone parallel anode design reduces current density and extends the service life of the furnace bottom by 50%.

Operation Notes

1. Strictly control the electrode insertion depth (1.2 - 1.8m) to prevent arc exposure and energy loss.
2. Maintain the water quality of the cooling system (conductivity ≤50μS/cm) to avoid electrode and furnace body burnout.
3. Use a high - basicity slag system (basicity R = 1.8 - 2.2) to improve the desulfurization rate (≥85%) and alloy recovery rate.

6. Comparison with Three - Electrode AC Submerged Arc Furnace

7. Development Trends

1. Ultra - High Power Integration: The rated power of a single furnace can reach 80 - 120MVA, with a four - electrode + multi - bottom anode structure to improve power density.
2. Intelligent Control: AI - based systems can automatically adjust electrode positions, current, and feeding speed, shortening the smelting cycle by 10% - 15%.
3. Energy - Saving and Environmental Protection Upgrades: Combine waste heat power generation and oxygen - enriched smelting to reduce energy consumption by 15% - 20%, and adopt a low - NOₓ combustion system to meet strict emission standards.