Air heater is an electric heating device mainly used to heat gas flow. The heating element of the air heater is a stainless steel electric heating tube. The inner cavity of the heater is equipped with multiple baffles (guide plates) to guide the gas flow, prolong the residence time of the gas in the cavity, thereby fully heating the gas, making the gas heating uniform, and improving heat exchange efficiency. The heating element of the air heater, the stainless steel heating tube, is made by inserting electric heating wire into a seamless steel tube, filling the gaps with magnesium oxide powder that has good thermal conductivity and insulation, and then shrinking the tube. When current passes through the high-temperature resistance wire, the heat generated diffuses through the crystalline magnesium oxide powder to the surface of the heating tube, and then transfers to the heated air to achieve the purpose of heating. Air heater works by mounting a primary coil with many turns and a secondary coil with fewer turns on the same iron core. The input-to-output voltage ratio equals the turns ratio, while energy remains constant. Therefore, the secondary coil generates a large current under low voltage. For induction heaters, the bearing is a short-circuited single-turn secondary coil that carries a large current under low AC voltage, thus generating a large amount of heat. The heater itself and the magnetic yoke remain at normal temperature. Since this heating method induces current, the bearing becomes magnetized. It is important to ensure that the bearing is demagnetized afterward so that it does not attract metal chips during operation. FAG induction heaters have an automatic demagnetization function. It uses the eddy current generated by metal in an alternating magnetic field to heat itself, commonly used in metal heat treatment and other applications. The principle is that when a thick metal is placed in an alternating magnetic field, current is generated due to electromagnetic induction. The current in the thick metal flows in a spiral path inside the metal, so the heat generated by the current is absorbed by the metal itself, causing the metal to heat up quickly. High-temperature resistance wires are evenly distributed inside a high-temperature resistant stainless steel seamless tube, and the gaps are densely filled with crystalline magnesium oxide powder with good thermal conductivity and insulation. This structure is not only advanced and highly efficient but also provides uniform heating. When current passes through the high-temperature resistance wire, the heat generated diffuses through the crystalline magnesium oxide powder to the surface of the metal tube, and then transfers to the heated part or air to achieve the purpose of heating.
