The common heating ways are listed for you. (I)
1. Induction heating: the conductor itself is heated by the thermal effect of induced current (eddy current) generated by the conductor in the alternating electromagnetic field. According to different heating process requirements, the ac power supply frequency used for induction heating includes power frequency (50 ~ 60 hz), intermediate frequency (60 ~ 10000 hz) and high frequency (higher than 10000 hz). Power frequency power supply is the ac power supply commonly used in industry, the power frequency of most countries in the world is 50 hz. The voltage applied to the induction unit by the power supply for induction heating must be adjustable. According to the power of the heating equipment and the capacity of the power supply network, high-voltage power supply (6 ~ 10 kv) can be used to supply power through the transformer. The heating equipment can also be directly connected to the 380-volt low-voltage power grid. If power supply used if generator set for a long time. It consists of if generator and drive asynchronous motor. The output power of such units is generally in the range of 50 ~ 1000 kw. With the development of power electronics, thyristor inverter is used as if power supply. The if power supply USES a thyristor to convert the power-frequency alternating current (ac) to direct current (dc) and then to the desired frequency (ac). Due to its small size, light weight, noiseless and reliable operation, the frequency conversion equipment has gradually replaced the if generator set.
The high frequency power supply usually raises the three-phase 380 volts voltage to about 20,000 volts high voltage first with the transformer, then USES the thyratron or the high voltage silicon rectifier element to rectify the power frequency alternating current to the direct current, then USES the electronic oscillation tube to transform the direct current to the high frequency, the high voltage alternating current. The output power of high-frequency power supply equipment ranges from tens to hundreds of kilowatts. An object heated by induction must be a conductor. When high-frequency ac current passes through the conductor, the conductor produces skin effect, that is, the conductor surface current density is large, the conductor center current density is small. Induction heating can uniform heating and surface heating. Smelting metal; At high frequencies, changing the shape of the coil, or sensor, allows arbitrary local heating.
2. Electron beam heating: using electrons moving at high speed under the action of electric field to bombard the surface of an object and make it heated. The main component of electron beam heating is electron beam generator, also known as electron gun. The electron gun is mainly composed of cathode, poly-beam, anode, electromagnetic lens and deflection coil. The anode is grounded, the cathode is connected to the negative high position, the focusing beam is usually at the same potential with the cathode, and an accelerating electric field is formed between the cathode and the anode. The electrons emitted from the cathode accelerate to a high speed under the action of accelerating electric field, which is focused by electromagnetic lens and controlled by deflection coil, so that the electron beam shoots towards the heated object in a certain direction. The advantages of electron beam heating are: (1) control of the electron beam current value Ie, can easily and quickly change the heating power; (2) the electromagnetic lens can be used to freely change the heated part or adjust the area of the electron beam bombardment part; (3) can increase the power density, so that the material at the point of bombardment in an instant evaporation.