Localization Process and Application Advantages of Submerged Arc Furnace Water-Cooled Cables

In the operation of the short network system of submerged arc furnaces used in calcium carbide (ferroalloy and industrial silicon) production, submerged arc furnace water-cooled cables are playing an increasingly important role. They not only improve electrical energy utilization efficiency but also reduce material costs.

During calcium carbide production, the short network system is responsible for efficiently transmitting electrical energy from the transformer to the furnace electrodes. Short network systems using water-cooled cables are highly regarded in the industry due to their compact structure and simple layout. On the premise of meeting process requirements, how to further reduce short network impedance, improve power utilization efficiency, and reduce unplanned downtime has become a key concern for engineering personnel.

1.Characteristics of Imported Submerged Arc Furnace Water-Cooled Cables

China began applying water-cooled cables in steelmaking equipment such as electric arc furnaces and power-frequency induction furnaces in the late 1970s. However, their application in calcium carbide (ferroalloy) submerged arc furnace systems has only emerged in recent years, benefiting from the digestion and absorption of foreign technologies.

In these large-capacity furnaces, each phase is typically equipped with 12 to 20 water-cooled cables. Imported cables feature a multi-strand copper construction, which effectively enhances insulation performance and cooling efficiency.

Each cable is made of pure copper wires with a diameter of 0.9 mm, braided into four copper strands with a diameter of 22 mm, resulting in an effective cross-sectional area of approximately 1200–1400 mm². To ensure reliable insulation, insulating tubes are used between the four strands to prevent friction.

In addition, the bare copper wires are covered with a layer of high-temperature-resistant rubber hose containing fiberglass, capable of withstanding temperatures of approximately 300°C, thereby ensuring insulation strength.

At both ends of the cable, non-magnetic stainless steel clamps are used for fastening, ensuring that cooling water is evenly introduced into the cable through the distribution holes in the cable joints.

2. Characteristics of Domestic Submerged Arc Furnace Water-Cooled Cables

At present, the commonly used connection method for water-cooled cable terminals in China is the plate-type flat connection. This connection structure offers excellent electrical conductivity and strong water sealing performance, along with easy installation and commissioning.

However, factors such as sealing ring material, machining precision, mechanical strength, and assembly process of the joint have a significant impact on both electrical conductivity and sealing performance.

Based on observations and operational experience, the use of large cross-section water-cooled cables in calcium carbide (ferroalloy) submerged arc furnace short network systems brings significant advantages:

2.1 Advantages of Large Cross-Section Design

The use of large cross-section water-cooled cables offers the following benefits:

1. It reduces the consumption of non-ferrous metal copper in the short network system and lowers maintenance costs.

2. Due to excellent cooling performance, the current density can reach approximately 4 A/mm², which is about twice that of conventional flexible bare cables.

3. Proper arrangement helps reduce skin effect and mutual inductance within the short network system.

Because of the high allowable current density, the copper consumption in the short network system can be reduced by about 50%, thereby lowering investment costs.

The structure of the short network system becomes more compact and rational, simplifying the layout of the furnace circulating cooling water pipelines and reducing vulnerable points, making maintenance more convenient.

After introducing water-cooled cables, the failure rate of the short network system is significantly reduced. The downtime caused by short network failures is reduced by approximately 70% compared to other configurations, while also lowering maintenance labor and repair costs.

2.2 Structural Improvements

Cable design has been optimized according to environmental conditions, thereby improving heat resistance and stability.

Based on local water quality and pressure conditions, the diameter of the cooling water distribution holes in the cable joints can be adjusted to optimize cooling performance. Especially under high water pressure conditions, this improvement can further enhance the cooling effect.

In addition, by applying a heat-resistant coating to the outer rubber sheath, the temperature resistance of the cable has been increased from 200°C to 350°C, improving insulation and mechanical strength while extending service life.

The domestically developed H96 copper alloy material not only ensures mechanical strength but also significantly reduces contact resistance, thereby improving electrical conductivity.

3. Application Characteristics and Usage Guidelines of Submerged Arc Furnace Water-Cooled Cables

Application Range and Advantages

Water-cooled cables can flexibly adapt to transformer loads and provide multiple connection methods along with high-temperature resistance.

They can meet the secondary current requirements of transformers with different capacities and offer a wide range of specifications. In addition, both plate-type and tubular connection methods are available, and customized designs can be provided to meet specific requirements.

Key advantages include:

1. The rubber outer sheath is coated with high-temperature-resistant flame-retardant material, ensuring that the operating temperature does not exceed 350°C during long-term operation. Even under short-term positive furnace pressure conditions, it remains non-flammable under flame exposure.

2. The stainless steel corrugated outer sheath allows the cable to operate in environments up to 500°C and provides excellent resistance to fire and burning.

3. The hollow core sintering process of the conductor effectively reduces the skin effect, thereby improving reactive power consumption in the short network system.

Through circulating water cooling technology, the current carrying capacity can reach 4.5 A/mm² per unit area.

Usage Precautions

To ensure safe and stable operation:

1. Stable water pressure and flow must be maintained during operation to ensure proper cooling performance.

2. The selected current density should not exceed 4.5 A/mm².

3. For special operating conditions, detailed calculations and customized design should be carried out in coordination with the supplier.