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Energy density refers to... Medium-frequency electric furnace The amount of power allocated per ton of energy in China. Medium-frequency electric furnace Electrical power can be divided into two components: one part is converted into thermal energy during the workpiece heating process, while the other part represents active power consumption. The remaining portion is copper loss in the power supply lines, which causes the water cables and induction coil to heat up. The cooling water then carries away this heat, effectively dissipating the reactive power. Clearly, the faster the melting rate of a medium-frequency induction furnace, the lower the reactive power loss. The higher the power density configuration of the furnace, the faster the melting rate. When the capacity of a medium-frequency induction furnace is less than 500 μg, the ratio of power supplied to the furnace’s capacity can reach between 0.9 and 2. For example, a 500 kg furnace might be equipped with a 450 W power supply, while a 200 kg furnace could be equipped with a 350 W supply. Under these conditions, molten iron can be melted within 45 to 24 minutes.

For furnaces with a capacity exceeding 1 ton, conventional equipment typically equips each ton of molten iron with a medium-frequency power supply. For example, a 2-ton furnace is equipped with a 1,250 W power supply; a 5-ton furnace, with 3,500 W; a 10-ton furnace, with 6,000 W; and a 20-ton furnace, with 12,000 W. In this way, the molten iron can be melted within approximately τ minutes. The primary reasons why modern medium-frequency induction furnaces, despite their high power density, cannot accommodate even higher power levels are limitations imposed by furnace lining life, production management practices, and supporting equipment. Since the furnace lining operating under high power densities is subjected to intense stirring by high-temperature molten slag, it places stringent demands on the material properties of the lining. Consequently, materials with low thermal conductivity must be selected.

High-quality furnace lining materials with low thermal expansion coefficient, high stability, and excellent fire resistance currently have no more suitable alternatives available domestically, nor has a rational and effective supply-and-sales service system been established yet. Furthermore, given the short melting cycle of high-power-density induction furnaces, it is necessary to equip them with corresponding automatic feeding devices—for instance, electric acid-suction cups, automated weighing systems equipped with digital displays and hooks, as well as advanced equipment for casting departments, raw material management, and ingredient calculation. The tasks involved are complex and extensive, requiring highly sophisticated technological equipment that exceeds the capacity of human resources. Therefore, computer-controlled and management systems must be adopted. Newly constructed furnace linings must utilize hydraulic propulsion and vibration-based furnace-building machinery; otherwise, the power utilization factor of the electric furnace will significantly decline, and the very purpose of high-power-density equipment will be undermined.