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The difference and principle of low frequency melting electric furnace and intermediate frequency furnace

First, smelting electric furnace
A general term for a melting method in which an electric furnace smelts electric energy as a heat source. Electric furnace smelting, preferably ductile iron and gray iron in turn smelting, if rotated smelting, can improve the life of many furnaces. According to the heating method, it is divided into arc melting, arc resistance double melting, and induction melting. Widely used in the refining of rare metals and their alloys, metals such as tin and nickel.
Second, the principle
The essence of electric furnace smelting is to add the charge into the ore electric furnace, and melt the charge under the action of electroheat and generate the same physical and chemical changes as the reverberatory furnace smelting to form copper slag, slag and flue gas. Heating and Melting Insert the electrode from the top of the furnace into the slag layer of the molten pool. When energized, the electrical energy is converted into heat. In the vicinity of the electrode, the current density and the gas film resistance between the electrode and the slag are both large, so a micro-arc discharge is generated in the vicinity of the electrode and a large amount of heat is concentrated, so that the temperature of the slag near the electrode is high; In the region, the current density is small and the slag resistance is smaller than the gas film resistance, the heat is less, the temperature is lower, and the temperature to the furnace wall is the lowest. Due to the uneven temperature distribution in the electric furnace, the slag near the electrode is too hot and has a small density, so it flows upward to the surface of the melt, and flows to the periphery of the electrode to heat the charge when it comes into contact with the charge to melt it; the formed melt temperature is low. , high density, easy to sink. Therefore, a convective circulation motion of the slag is formed in the molten pool around the electrode, and heat transfer and melting are continuously performed and various physical and chemical changes are the same as those of the reverberatory furnace. It can be seen that the heat transfer of the electric furnace relies on the superheated slag to heat the charge, and the melting and reaction process is carried out inside the charge. For this reason, the furnace furnace gas temperature is low, the furnace gas does not directly participate in the reaction, and the electric energy efficiency is high.
Low frequency melting furnace and intermediate frequency furnace
The difference and principle of low frequency melting electric furnace and intermediate frequency furnace
Power supply and regulation
The large ore electric furnace has 6 electrodes, each pair of electrodes is connected with a single-phase transformer. The primary coil of the transformer has several contact points (number of stops), which can make the secondary voltage have different values. With the difference of the secondary voltage, the power supplied to the furnace is also different. The higher the voltage, the higher the power, and the more heat, so when the furnace is turned on, the furnace is shut down, or the capacity of the furnace or bed is changed, the voltage can be changed. The method is to adjust the electric power supplied into the furnace, that is, to change the amount of heat supplied. However, when the electric furnace is operated under a certain voltage, the value of the secondary current fluctuates due to the fluctuation of the molten pool load. When the current reaches the maximum current of the transformer, the fluctuation of the current will force the transformer protection device to automatically trip; instead of the maximum current operation, the fluctuation of the current will reduce the efficiency of the transformer. In order to change this situation, the lift electrode is often used to adjust the load of the molten pool. In order to maintain a certain current value, the load of the molten pool must remain unchanged. When the specific resistance of the slag changes due to changes in film state, pile size and position, slag composition and depth, it can be increased or Reduce the depth of the electrode to maintain the balance. The lifting of the electrodes can be carried out automatically or by means of a hoisting machine.
Third, what is the difference between the intermediate frequency furnace and the low frequency furnace? The intermediate frequency furnace (see if you are used for warm forging or smelting), the general working frequency is 1K-10K.20K--100K segment is generally called super audio. 100K-500K is the high frequency band, and then The upper frequency is UHF. The working frequency determines the different devices used. The intermediate frequency fission circuit generally uses thyristor, and the high frequency generally uses the MOS FET tube with faster switching speed. Effect: Different frequency ranges have different The range of adaptation. The higher the frequency, the stronger the skin effect, the shallower the depth of the induced current flowing into the workpiece. Therefore, the high frequency induction is widely used for surface quenching welding. The intermediate frequency has a low operating frequency and the current transmission depth is deep. Therefore, it is widely used in warm forging smelting. However, some rare metal smelting still uses high frequency melting because of the low magnetic permeability.
The difference and principle of the low-frequency melting furnace and the intermediate frequency furnace have been very clear to us. The efficiency of this low-frequency melting furnace is very high.
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