Views: 5 Author: Site Editor Publish Time: 2022-01-26 Origin: Site
An electric furnace that uses the induction electric heating effect of the material to heat or melt the material. The basic component of the induction furnace is an induction coil wound with a copper tube. An alternating voltage is applied to both ends of the induction coil to generate an alternating electromagnetic field. The conductive material is placed in the induction coil. The electromagnetic induction generates eddy current in the material, and the electric resistance is converted into heat energy to heat the material; therefore, it can also be considered. Induction heating is a direct heating type resistance heating.
The characteristic of induction heating is that the electric heating power (current distribution) transformed in the heated material is very uneven, with the largest surface and the smallest center, which is called the skin effect. In order to improve the electric heating efficiency of induction heating, the power supply frequency should be appropriate. Small smelting furnaces or the surface heating of materials use high frequency electricity, and large smelting furnaces or deep penetration heating of materials use medium frequency or power frequency electricity. The induction coil is a load with considerable inductance, and its power factor is generally very low. In order to improve the power factor, the induction coil is generally connected in parallel with a capacitor, which is called a compensation capacitor. The gap between the induction coil and the material should be small. The induction coil should be made of a square copper tube with water cooling in the tube. The inter-turn gap of the induction coil should be as small as possible and the insulation should be good. The induction heating device is mainly used for the melting and casting of steel, copper, aluminum and zinc. It has fast heating, less burnout, high degree of mechanization and automation, and is suitable for deployment on automatic operation lines.
In production, after each furnace of metal smelting is completed, the molten pool cannot be emptied, and a part of the melt must be retained as the starting melt of the next furnace. The temperature of the melting channel is higher than that of the molten pool, and it is subject to the erosion of the melt flow, so the furnace lining of the melting channel is easily damaged. In order to facilitate maintenance, the inductors of modern furnaces are made into easy-to-replace assembly parts. The capacity of the furnace ranges from a few hundred kilograms to more than one hundred tons. The furnace is supplied with power frequency electricity. Since the iron core made of silicon steel sheet is used as the magnetic path, the electric efficiency and power factor are very high. Furnace furnace is mainly used for the melting of cast iron, copper, zinc, brass, etc., and can also be used as a mixed melt to store and heat the melt.
An electric furnace that uses electric arc heating to smelt metals and other materials. According to the heating method, it is divided into three types:
1. Indirect heating electric arc furnace. The arc is generated between the two electrodes, does not touch the material, and heats the material by thermal radiation. This kind of furnace is noisy and low in efficiency, and is gradually eliminated.
2. The electric arc furnace is directly heated. The electric arc is generated between the electrode and the material to directly heat the material; the steelmaking three-phase electric arc furnace is the most commonly used direct heating electric arc furnace.
3. Submerged arc electric furnace, also known as reduction electric furnace or submerged electric furnace. One end of the electrode is buried in the material layer to form an electric arc in the material layer and use the resistance of the material layer to heat the material; commonly used for smelting ferroalloy, smelting matte and matte, and producing calcium carbide and so on.
A vacuum arc furnace is an electric furnace that uses an electric arc to directly heat and smelt metal in a vacuumed furnace body. The gas in the furnace is thin, and the arc is mainly generated by the vapor of the molten metal. In order to stabilize the arc, DC power is generally supplied. According to the characteristics of smelting, it is divided into metal remelting furnace and casting furnace. According to whether the electrode is consumed (melted) during the smelting process, it is divided into consumable furnaces and non-consumable furnaces. Most of the industrial applications are consumable furnaces. The vacuum electric arc furnace is used to smelt special steel, active and refractory metals such as titanium, molybdenum, and niobium.