DC Plasma Electric Arc Furnace (DC PAF)

1. Core Principle & Equipment Structure

1.1 Working Principle

1. Arc ignition: A DC voltage is applied between the cerium-tungsten electrode of the plasma torch and the water-cooled copper nozzle. Argon gas is introduced, and a high-frequency igniter breaks down the gas to form a non-transferred arc (pilot arc).
2. Transfer: The torch is lowered to connect the arc with the bottom anode; the circuit switches to form a transferred arc (main arc) as the primary heat source.
3. Melting: The plasma arc temperature reaches 10,000–20,000 ℃, rapidly melting the charge. Inert gas can be used to control the atmosphere for non-oxidation or reduction smelting.

1.2 Main Components

• Plasma torch: Water-cooled cerium-tungsten electrode, copper nozzle, gas circuit
• Furnace system: Water-cooled furnace lid, refractory lining, bottom anode, electromagnetic stirring coil
• Power supply system: DC rectifier power supply, reactor, control system
• Auxiliary system: Gas supply, water cooling, hydraulic lifting

2. Key Technical Parameters

2.1 Electrical & Power Parameters

• Rated power: 500 kVA – 10 MVA+
• Input voltage: 380V / 690V / 6kV / 10kV
• Operating voltage: 500–800 V (DC)
• Operating current: Hundreds to thousands A
• Power factor: 0.70–0.86

2.2 Process & Atmosphere Parameters

• Arc core temperature: Up to 20,000 ℃
• Working gas: Argon, nitrogen, hydrogen
• Gas flow rate: 10–100 Nm³/h
• Vacuum degree (optional): 6.7×10⁻³ Pa

2.3 Cooling & Operation Parameters

• Cooling water flow: 50–160 m³/h
• Cooling water pressure: 2–4 bar
• Electrode lifting stroke: ≤ 150 mm
• Lining campaign life: ≥ 150 heats

3. Core Advantages

• Ultra-high temperature & high efficiency: Fast melting, low energy consumption
• Controllable atmosphere, no carburization: Suitable for ultra-low carbon steel
• High alloy recovery: ≥ 96%
• Grid-friendly: Stable arc, low harmonics, low grid impact

4. Typical Applications

• Special steel: stainless steel, bearing steel, superalloys
• Refractory metals: W, Mo, Ta, Nb, Zr, Ti
• Metal recycling & industrial waste treatment
• New materials: ceramics, composite materials