The advantages of smelting molten iron in the intermediate frequency furnace and the comparison analysis of the industrial frequency furnace and electric arc furnace
Intermediate frequency electric furnace, intermediate frequency induction furnace is to convert three-phase power frequency alternating current into direct current after rectification, and then convert the direct current into adjustable intermediate frequency current, supply the intermediate frequency alternating current flowing through the capacitor and the induction coil, in the induction coil Generate high-density magnetic lines of force, and cut the metal material contained in the induction coil, which produces a large eddy current in the metal material. This kind of eddy current also has some properties of intermediate frequency current, that is, the free electrons of the metal itself flow in the resistive metal body to generate heat.
For example, 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. The temperature of the energized coil itself is already very low, but the surface of the cylinder is heated to redness or even melting. , And the speed of redness and melting can be achieved only by adjusting the frequency and the strength of the current. If the cylinder is placed in the center of the coil, then the temperature around the cylinder is the same, and the heating and melting of the cylinder will not produce harmful gas or bright light to pollute the environment.
It is precisely because of the above advantages that the intermediate frequency induction furnace has been widely used in various industries.
For example, in the roll industry: 3 years ago, most roll factories used cupola coke furnaces to smelt molten iron. The composition of the molten iron from the cupola cannot be adjusted, the temperature is difficult to control, the quality of cast rolls is poor, the yield is low, and the benefit is poor. Moreover, the molten iron temperature of this cupola cannot rise to 1600°C, so high-grade steel rolls cannot be produced, which makes my country’s high-grade rolls dependent on imports.
In the past two to three years, my country’s main roll production plants have successively adopted intermediate frequency induction furnaces to smelt molten iron and alloy steel to produce rolls, which has brought my country’s roll production level to a big step and achieved obvious benefits.
In the foundry industry, because foreign intermediate frequency electric furnaces are expensive, many domestic users are discouraged and can only buy industrial frequency electric furnaces to smelt molten iron and molten steel. Since the 50-cycle power frequency is too low, the power compensation is difficult after the first furnace is started, and it can only be compensated slowly. It will take a few hours to achieve full power output, which wastes time and reduces efficiency. After the molten iron is smelted, it is not possible to pour out all the molten iron, and a part of the molten iron must be left in the furnace, otherwise the smelting cannot be started for the second time. Due to the low frequency, the molten iron rolls too much in the furnace, stirring the slag and inclusions in the liquid, which affects the quality of the molten steel. Users who use this device have a hard time saying;
Therefore, recently, more and more units have transformed industrial frequency furnaces into intermediate frequency electric furnaces. After a foundry changed a set of 3-ton industrial frequency furnace to an intermediate frequency furnace, it was easy to use, and the benefit was significantly improved. Therefore, the industrial frequency furnace was gradually eliminated by the smelting industry and replaced by an intermediate frequency induction furnace.
In the early days of the smelting industry, electric arc furnaces were also used a lot. This kind of equipment uses carbon rods to short-circuit each other to generate short-circuit large currents and generate high temperatures to melt molten iron or molten steel. The disadvantage of this kind of equipment is that it will produce dazzling arc at the same time when it generates high temperature, which will stab the eyes of the operator. At the same time, it will produce harmful powder gas, which will pollute the environment. It also burns, which reduces the effective yield of molten steel and elements, increases the cost, and burns the furnace wall at the same time. 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 used intermediate frequency electric furnaces to replace electric arc furnaces in order to improve corporate efficiency.