Primary air fan

Function

 

Primary air plays an important role in boiler combustion in coal fired power plants. It supplies oxygen for burning and heat for fuel drying, also it conveys pulverized coal to burner when passing through coal mill.

 

Fresh air from primary air fan (forced draft) will go two separate passes. Part of primary air going through air preheater is called hot primary air, which would dry and convey coal powders. The other part is called cold primary air. Part of cold primary air is used as sealing air for coal pulverizer and feeder to avoid leakage of coal powders. Finally, hot/cold primary air meet and mix at the inlet of coal pulverizer to adjust temperature at outlet of pulverizer.

 

For boiler with capacity lower than 300MW, normally centrifugal primary air fan is used. For boiler with capacity higher than 300MW, axial flow fan with adjustable rotor blade is used.

 

4-73 primary air fan is suitable with 20-670tph steam boiler in thermal power plant. It is featured with big air volume, low noise, high efficiency. 4-73 primary air fan could be used to convey ambient or high temperature clean gas, dusty gas, flammable gas, corrosive gas, powders & particles, etc. Its wide application includes: building ventilation, mine ventilation, clinker cooling, material conveying, forced/induced draft of boiler & furnace & kiln, air purification, dust collection.

 

Parameter

 

Air volume: 10696-952530m3/h
Pressure: 615-8302Pa
Power: 5.5-1600kW
Model: 8D、9D、10D、11D、12D、14D、16D、18D、20D、22D、25D、28D、29.5D, etc.

 

Features

 

1. Big air volume with desired pressure, low noise, stable operation for medium with high temperature.
2. Optimized blade mounting angle, longer service life.
3. Damper or VFD motor for flexible adjustment of pressure and volume.
4. Impeller and shaft made of carbon steel or alloy steel to maintain reliable strength in different cases.
5. No need for bearing cooling device for primary air fan with impeller less than 1400mm diameter working in normal temperature.
6. Annealing treatment for impeller to avoid internal stress.
7. Well balanced to ensure stable operation.