Analysis and Advantages of Domestic Production of Water-Cooled Cables for Submerged Arc Furnaces

Analysis of the Localization Process and Application Advantages of Water-Cooled Cables for Submerged Arc Furnaces

The application of water-cooled cables in the short-network system of calcium carbide (ferroalloy, industrial silicon) submerged arc furnaces is becoming increasingly important. It not only improves energy utilization efficiency but also reduces material costs. In the calcium carbide production process, the short-network system is responsible for efficiently transferring the transformer's output energy to the furnace electrodes. Short-network systems using water-cooled cables for submerged arc furnaces have attracted much attention in the industry due to their compact structure and simple layout. While meeting production process requirements, how to further reduce the impedance of the short-network system, improve energy utilization efficiency, and reduce the failure rate has become an important issue for engineering technicians.

1. Characteristics of Imported Water-Cooled Cables for Submerged Arc Furnaces

My country began applying water-cooled cables to steelmaking equipment such as electric arc furnaces and power frequency induction furnaces in the late 1970s. However, the introduction of this technology into calcium carbide (ferroalloy) submerged arc furnace systems is a recent development, benefiting from the assimilation and absorption of foreign experience. In these large-capacity furnaces, each phase is typically equipped with 12 to 20 water-cooled cables. Imported cables utilize multi-strand copper stranded cables, effectively improving insulation performance and cooling efficiency. Each cable is made of 0.9 mm diameter pure copper wire stranded into four 22 mm diameter copper strands, with an effective cross-sectional area of approximately 1200 to 1400 square millimeters. To ensure good insulation performance, the four copper strands are isolated by insulating tubing to prevent mutual friction. Furthermore, the bare copper wire is covered with a high-temperature resistant rubber hose containing glass fiber, capable of withstanding temperatures of approximately 300 degrees Celsius, thus ensuring the cable's insulation strength. At both ends of the cable, anti-magnetic stainless steel clamps are used for fastening, ensuring that cooling water can be evenly injected into the cable through the drainage holes on the cable joint.

2. Characteristics of Domestic Water-Cooled Cables for Submerged Arc Furnaces

Currently, the most commonly used water-cooled cable joint connection method in China is the plate-type planar connection. This connection method not only has excellent conductivity but also extremely strong cooling water sealing, coupled with its simple installation and commissioning characteristics, making it an excellent connection structure. However, the material, machining precision, mechanical strength, and assembly process of the sealing ring in the joint all have a profound impact on the conductivity and cooling water sealing performance of the water-cooled cable. Through observation and summarizing the performance of water-cooled cables in actual operation, we found that using large-section water-cooled cables in the short-network system of calcium carbide (ferroalloy) submerged arc furnaces brings significant advantages:

2.1 Advantages of Large Cross-Section

Using large-section water-cooled cables not only reduces the amount of copper used in the short-network system but also lowers maintenance costs. The excellent cooling effect of water-cooled cables allows for a current density of up to approximately 4A, which is twice the allowable current density of bare flexible cables. Furthermore, their rational arrangement helps reduce the skin effect and self-inductance coefficient in the short-network system.

Due to the high allowable current carrying capacity of water-cooled cables, the amount of copper used in the short-network system can be halved, thereby reducing investment costs. The short-network system using water-cooled cables has a more compact and rational structure, simplifying the layout and arrangement of the furnace's circulating cooling water pipes, reducing vulnerable parts, and making maintenance more convenient.

After introducing water-cooled cables, the failure rate of the electric furnace short network was significantly reduced. The total power outage time and losses due to short network system failures were reduced by approximately 70% compared to other short network configurations, while also reducing maintenance time and costs.

2.2 Structural Improvements

The cable design was optimized for environmental conditions, thereby improving heat resistance and stability. The diameter of the cooling water diffuser holes on the cable joints was appropriately adjusted according to local water quality and pressure conditions to optimize the water cooling effect. This improvement further enhances the cable's cooling effect, especially under high water pressure environments. Furthermore, by applying a heat-resistant coating to the outer layer of the rubber sheath, the cable's heat resistance was increased from 200 degrees Celsius to 350 degrees Celsius, thereby strengthening the cable's outer insulation and extending its service life.

The domestically developed H96 copper alloy material significantly reduces contact resistance and improves conductivity while ensuring component strength.

3. Application Characteristics and Usage Instructions for Water-Cooled Cables in Submerged Arc Furnaces

Application Scope and Advantages: Water-cooled cables flexibly adapt to transformer loads, providing various connection methods and high-temperature resistance characteristics. Water-cooled cables for submerged arc furnaces can flexibly adapt to the secondary current-carrying capacity requirements of transformers of varying capacities, offering a wide range of specifications. Furthermore, the cables provide both plate and tubular connection methods and support special customization to meet specific needs. Their significant advantages include:

① The rubber sheath of the water-cooled cable for submerged arc furnaces uses a high-temperature resistant flame-retardant coating, ensuring that its temperature does not exceed 350℃ under long-term operating conditions, and it remains non-combustible even under short-term positive pressure furnace gas conditions.

② The stainless steel corrugated tube sheath design allows the cable to operate at temperatures up to 500℃ and provides excellent fire resistance.

③ The hollow-core firing process of the cable core effectively reduces the skin effect, thereby improving reactive power consumption in short-circuit networks.

Through circulating water cooling technology, the current-carrying capacity per unit area of the cable can be increased to 4.5A/mm².

Usage Precautions: Ensure stable water pressure and flow rate during operation, and that the current density does not exceed the standard value. During operation, it is essential to ensure stable water pressure and flow rate to guarantee cable performance. When selecting current density, it should not exceed 4.5 A/mm² to ensure the safe operation of the cable. For special application requirements, please contact the supplier for detailed calculations and customized design to suit specific operating conditions.