The process
A hot air generator burns fuel and mixes the products or the heat exchanger air with dilution air to feed a dryer. The hot air fan carries the mixed stream to the dryer at the required temperature, and the combustion air blower serves the burner.
The gas at the fan
Clean air at elevated temperature from a dryer, oven or cooling duty. The selection is made at the hot density, with the shaft and bearings arranged for continuous hot running.
Selection for this duty
| Blade form | Backward curved or aerofoil for the best efficiency on clean gas |
| Material of construction | Mild steel |
| Drive and bearings | Direct coupled, shaft cooling disc, bearings in a pedestal outside the gas stream, allowance for thermal growth |
| Density at the fan | At about 250°C the gas density is close to 0.67 kg/m³, 56% of standard air. Pressure developed and power drawn fall in the same ratio, so the selection is made at this density and the motor is checked at cold start. |
Supplies combustion air to a boiler or furnace, pushing ambient air through the air heater and into the windbox against the furnace draft. Clean air, so the blade is chosen for efficiency. Client-stated blade types for the FD Fan in general: Backward curved and backward inclined.
Industries
Other fans in hot air generators
FD Fan in other processes
Bagasse Fired BoilersRice Husk Fired BoilersAFBC BoilersCFBC BoilersPulverised Coal Fired BoilersOil and Gas Fired BoilersBiomass Fired BoilersThermic Fluid HeatersBlast Furnace Hot Blast StovesRefinery Fired HeatersPulp Mills and Recovery BoilersDyeing and Finishing HousesCaptive Power PlantsDistillery Spent Wash Incineration Boilers
Services on this fan
Fan and System Performance TestingFan Energy AuditRetrofit of Low Efficiency FansDynamic Balancing and Vibration AnalysisCondition Monitoring and TroubleshootingInstallation, Commissioning and After-sales Support
Information needed to select or quote
- Duty point. Volume flow and static pressure at the fan inlet, with the gas density and temperature or the conditions to derive it.
- Operating conditions. Site altitude, normal operating temperature and continuous or intermittent duty.
- Gas stream. Dust loading and particle size, corrosive species, moisture, upset temperature and any tendency of the material to deposit on the impeller.
- Mechanical. Rotation viewed from the drive end, discharge orientation and motor power.