The air duct flue gas heater is a device specially used to heat and treat the air duct flue gas. It usually consists of heating elements, control devices and shells, etc., and can be widely used in various industrial furnaces, incinerators, power plants and other places where flue gas needs to be emitted. By heating the flue gas to a certain temperature, harmful substances such as moisture, sulfides, and nitrogen oxides in the flue gas can be effectively removed to purify the air and reduce pollution.