The bright new star in heating equipment-medium frequency induction heating furnace

The intermediate frequency induction heating furnace rectifies the three-phase power frequency alternating current into direct current, and then converts the direct current into an adjustable intermediate frequency current to supply the intermediate frequency alternating current flowing through the capacitor and induction coil. That is to say, high-density magnetic field lines are generated in the induction coil, cutting the metal material contained in the induction coil, and generating large eddy currents in the metal material. This kind of eddy current also has some properties of intermediate frequency current. For example, if a metal cylinder is placed in an induction coil with alternating intermediate frequency current, the metal cylinder is not in direct contact with the induction coil, and the temperature of the energized coil itself is already very low, but The surface of the cylinder is heated until it turns red or even melts, and the speed of this reddening and melting can be achieved by adjusting the frequency and the intensity of the current. If the cylinder is placed in the center of the coil, the temperature around the cylinder will be the same, and the heating and melting of the cylinder will not produce harmful gases or strong light to pollute the environment. That is, the free electrons of the metal itself generate heat when flowing in a resistive metal body. Because of the above advantages, medium frequency electric furnaces have been widely used in various industries.

In the roll industry, three years ago, most factories used cupola coke furnaces to smelt molten iron. The composition of the molten iron coming out of the cupola furnace could not be adjusted, and the temperature was difficult to control. The cast rolls were of poor quality, with low yield and poor efficiency. Moreover, the temperature of the molten iron in this cupola cannot rise to 1600°C, so it cannot produce high-grade steel rolls, making my country's high-grade rolls dependent on imports. In the past few years, my country's major roll manufacturers have successively adopted medium-frequency induction heating furnaces to smelt molten iron and alloy steel to produce rolls, which has brought my country's roll production level to a big level and achieved obvious benefits.

In the foundry industry, due to the high price of foreign intermediate frequency electric furnaces, many domestic users are discouraged and can only purchase power frequency electric furnaces to smelt molten iron and molten steel. Because the power frequency of 50 cycles is too low, it is difficult to compensate for the power after the first furnace is started. It can only be compensated slowly. It will take several hours to achieve full power output, which wastes time and reduces efficiency. After the molten iron is smelted, you cannot pour out all the molten iron. You must leave some molten iron in the furnace, otherwise the smelting cannot be started the second time. Due to the low frequency, the molten iron rolls too much in the furnace, stirring slag and inclusions into the liquid, affecting the quality of the molten steel. Users who use this kind of equipment have unspeakable hardships, so recently more and more units are converting power frequency furnaces into medium frequency electric furnaces.

After a certain foundry changed a set of 3-ton power frequency furnaces to medium frequency furnaces, they were easy to use and the efficiency was significantly improved. Therefore, the power frequency furnaces were gradually eliminated by the smelting industry, and the replacement by medium frequency induction heating furnaces became the general trend. In the early days of the smelting industry, electric arc furnaces were also widely used. This type of equipment uses electrodes to short-circuit each other through carbon rods to generate a short-circuit high current and then generate high temperatures to melt molten iron or molten steel. The disadvantage of this kind of equipment is that when it generates high temperature, it will produce dazzling arc light, which will hurt the eyes of the operator. It will also produce harmful powder gas and pollute the environment. When it generates high temperature above 1000℃, it will remove the precious elements in the molten steel. It also burns, which reduces the effective yield of molten steel and elements, increases the cost, and burns the furnace wall. In particular, the lining life of small-tonnage electric furnaces is very low. The relevant departments of the State Economic and Trade Commission have clearly stipulated that electric arc furnaces below 10 tons cannot be used. Therefore, these users have replaced electric arc furnaces with medium-frequency electric furnaces to improve corporate efficiency.