Introduction to electric furnace knowledge

 

Electric furnace is a heating furnace that converts the electric energy in the furnace into heat to heat the workpiece. Compared with fuel furnaces, the advantages of electric furnaces are: the atmosphere in the furnace is easy to control, and can even be vacuumed; the material is heated quickly, the heating temperature is high, and the temperature is easy to control ; The production process is easier to realize mechanization and automation; good labor and hygiene conditions; high thermal efficiency; good product quality.

Electric furnaces in the metallurgical industry are mainly used for smelting, heating and heat treatment of iron and steel, ferroalloys, and non-ferrous metals. Industrial-scale electric furnaces appeared at the end of the 19th century. Since the 1950s, the demand for metallurgical products has increased rapidly, and electricity costs have decreased with the development of the power industry. The proportion of electric furnaces in metallurgical furnace equipment has increased year by year.

Electric furnaces can be divided into resistance furnaces, induction furnaces, electric arc furnaces, plasma furnaces, electron beam furnaces, etc.

Resistance furnace is an electric furnace that uses Joule heat generated by current passing through a conductor as the heat source. According to the method of electric heat generation, resistance furnaces are divided into direct heating and indirect heating. The direct heating resistance furnace can be made into a vacuum resistance heating furnace or a protective gas resistance heating furnace. In powder metallurgy, it is often used for sintering tungsten, tantalum, niobium and other products.

Induction furnace, an induction furnace is 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. AC 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, and the eddy current is generated in the material due to electromagnetic induction, which is subject to resistance. It turns electric energy into heat energy to heat the material; therefore, induction electric heating can also be regarded as a direct heating resistance electric heating.

Electric arc furnace, an electric furnace that uses arc heat to smelt metals and other materials. According to the heating method, it is divided into three types: ①Indirect 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. ②The electric arc furnace is directly heated. The electric arc is generated between the electrode and the material to directly heat the material; the steel-making three-phase electric arc furnace is the most commonly used direct heating electric arc furnace. ③Submerged 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 arc in the material layer and use the resistance of the material layer to heat the material; it is often used for smelting iron alloys.

Plasma furnace is an electric furnace that uses plasma generated when working gas is ionized for heating or smelting. Plasma-generating devices, usually called plasma guns, are classified into arc plasma guns and high-frequency induction plasma guns.　　 Electron beam furnace, an electric furnace that bombards materials with high-speed electrons to heat and melt them. In the vacuum furnace shell, the cathode is heated by a low-voltage electric filament to make it emit electrons. The electron beam is accelerated by the high-voltage electric field that accelerates the anode, bombarding the metal material at the anode, and transforming electrical energy into heat. Because the electron beam can be highly dense through the electromagnetic focusing device, it can generate very high temperatures in the bombarded parts of the material. The electron beam furnace is used to smelt special steel, refractory and active metals.