The induced draft fan is a device that generates negative pressure through the rotation of the impeller, and then extracts air from the system (equipment). It is generally installed at the end of the boiler to extract hot flue gas from the furnace.
In daily life, ventilators are usually divided into induced draft fans (for negative pressure) and blowers (for positive pressure) according to the different ways of using positive and negative pressure.
Induced draft fans are widely used for ventilation, dust exhaust and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and induced air in boilers and industrial furnaces; cooling and cooling in air conditioning equipment and household appliances Ventilation; drying and selective delivery of grains; air source of wind tunnel and inflation and propulsion of hovercraft, etc. The working principle of an induced draft fan is basically the same as that of a turbo compressor, except that the gas flow rate is low and the pressure changes little. Generally, there is no need to consider the change of the gas specific volume, that is, the gas is treated as an incompressible fluid.
Because the hardness of the composite ceramic layer on the working surface of the fan impeller is HRA≥86 (toughened alumina composite material), the second sintered silicon nitride toughened ceramic or zirconia toughened alumina ceramic is used for the severely worn parts, and the highest can reach HRA94 or more. Its resistance to particle erosion and abrasion is at least 5 times higher than that of ordinary tungsten carbide surfacing, spray spray welding, and alloy powder block welding, which is more than 100 times higher than the base 16Mn steel; the thickness of 1.5mm ceramic sheet has actually been used. Up to five years, the average wear is less than 0.2mm.
