Forced-draft fans focus the pressure and volume at the outlet of the fan to push air through a system, creating positive air pressure. Applications calling for positive pressure include boilers, glass furnaces, and ovens. Accommodating higher process inlet temperatures, industrial applications use forced draft fans to push ambient air through burners to preheat air for boiler system efficiency. These industrial applications often also use inlet or outlet dampers to control and maintain the system pressure.
The Upside of Forced Draft Fans
“Pushing” ambient air involves less wear-and-tear on the fan than dirty and hot airstreams. The location of the forced draft fan frequently allows for accessibility of upper bearings and the fan blades for maintenance and protects the fan and v-belt assembly from the hot-air stream. It also requires less structural support and can offer a longer mechanical life than many induced draft fans.
What to Watch for with Forced Draft Fans
While ambient air may not be as hard on the fan compared to more extreme conditions, fan/system imbalance and excessive vibration can still be a problem. It’s critical that fan vibration levels are monitored and addressed if they exceed recommended levels.
Fan Designs Commonly Used in Forced Draft Applications
AirPro offers several different fan types used in forced draft applications. They include:
- Backward Curved (BCHS)
- Backward Inclined (BIHS)
- High-Pressure Radial Open (HPRM / HPRL)
- High-Pressure Radial Shrouded (HPSM / HPSL)
- Industrial Exhauster Air Handling (IEAH)
- Industrial Exhauster Paddle Wheel (IEPW / IEFB)
- Industrial Exhauster Radial Shrouded (IERS)
- Radial Tipped (RTHS)
In addition to the various fan types used for forced draft applications, we also custom design important accessories like dampers, inlet boxes, and wind boxes. These work in concert with the fan to control pressure and maintain stability.
Contact an AirPro application engineer to discuss your industrial application.