Boiler induced draft fans extract flue gas from the boiler to maintain negative pressure. The flue gas passes through an air preheater and an electrostatic precipitator before entering the induced draft fan. The fan then delivers the gas to the desulfurization system and releases it into the chimney. Induced draft fans must withstand corrosion from high-temperature flue gases containing SO2, HCl, H2S, NH3, and dust friction. The dust content in the fan before the precipitator is high, requiring ZS-1042 desulfurization and corrosion-resistant paint for protection. After the precipitator, the dust content in the fan is low, so a flue gas corrosion-resistant paint is sufficient for protection.

The boiler induced draft fan is installed at the rear of the boiler, drawing air from the furnace, creating a negative pressure inside. Fresh external air enters the furnace (some through the forced draft fan) to accelerate the combustion of fuel within the furnace.

Boiler induced draft fans are widely used in factories, mines, tunnels, cooling towers, vehicles, ships, and buildings for ventilation, dust extraction, and cooling; ventilation and induced draft for boilers and industrial furnaces; cooling and ventilation in air conditioning equipment and household appliances; drying and sorting of grains; wind tunnel air sources, and air cushion ship inflation and propulsion, etc.

The working principle of the boiler induced draft fan is essentially the same as that of a turbine compressor, but due to the lower gas flow velocity and minimal pressure changes, it is generally not necessary to consider the variation in gas specific volume, treating the gas as an incompressible fluid.