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

The air preheater is located in the region of the boiler's flue gas with low temperature, recovers the waste heat of the flue gas, reduces the exhaust gas temperature, and preheats the required air for combustion, thereby increasing the initial temperature of fuel and air. This strengthens the ignition and combustion process of the fuel, reduces the incomplete heat loss of the fuel, and further improves the thermal efficiency of the heating furnace.