An air preheater is a heat exchange device that utilizes the waste heat from the flue gas at the end of a heating furnace to heat the air required for combustion, aiming to reduce flue gas temperature and improve the overall thermal efficiency of the heating furnace.

The air preheater is situated in the low-temperature region of the heating furnace flue gas, recovering the waste heat of the flue gas, reducing the exhaust gas temperature, and preheating the required combustion air. This increases the initial temperature of the fuel and air, enhancing the ignition and combustion process of the fuel, reducing the heat loss from the fuel, and further improving the thermal efficiency of the heating furnace.