Dilution Air Fans
Dilution Air Fan Applications
Power plants and other industrial operations that use combustion in furnaces, boilers, incinerators, and cooling systems must clean emissions before releasing them into the atmosphere. A dilution air fan, often paired with an SCR System, injects clean ambient air into the system, diluting the contaminated gas stream, enabling the plant to meet pollution control requirements mandated by the US Environmental Protection Agency (EPA).
The dilution air fan reduces the concentration of contaminating, usually Carbon Dioxide (CO2) or Nitrogen Oxide (NOx), in plant emissions by injecting fresh air into the airstream between the operations and exhaust. To do that, the application requires an industrial dilution air blower to introduce clean forced draft air into the system.
Primary Industries for Dilution Air
Industries that produce Volatile Organic Compounds (VOCs) or Hazardous Air Pollutants (HAPs) like NOx as byproducts of their operations require pollution control mechanisms. Coal and Gas Power Plants and any industrial operation that needs to exhaust dirty air often use Dilution Air for pollution control.
Dilution Air Blower Technology Selection & Specification
Because of the strict EPA emission requirements, pollution control provisions like Dilution Air Fans are essential to many industrial operations. That makes it critical to design the blowers for reliable performance and long life.
One important aspect of the specification is sizing for stability at all required operating points on the fan curve. Due to the variable flow requirements of this application, selecting a fan that operates too far to the left on the static pressure curve could put you at risk of operating in a surge condition, which often leads to premature failure. If you select the right fan, you’ll still be able to operate efficiently even with the extra room on the curve.
Fans Commonly Used to Provide Dilution Air
Fan Arrangements, Accessories, & Design
Fan Arrangements indicate how the motors mount to and drive the fans. For dilution air fans, we typically use direct-drive arrangements, usually an Arrangement 7 for very large blowers, otherwise Arrangement 4 or Arrangement 8.
Industrial Fan Designs Commonly Used for Calciner Rotary Kilns
Often, the amount of airflow is regulated by variable frequency drives and/or inlet dampers. Using these components together as a unit, the boiler’s efficiency increases, which results in better system reliability and increased energy savings.
Accessories & Design
When it comes to design and accessories, it’s all about protection, and optimizing operations, maintenance, and life of the fan and bearings. In industrial dilution air applications, we often recommend:
- Inlet Filter or Screen to keep the airstream clean and avoid introducing items that could be harmful to downstream equipment & process
- Inlet Silencer for noise control
- Inlet Vane Damper, Variable Frequency Drive (VFD), Outlet Damper, or a combination for airflow control
- Inlet Box if space is tight for the ductwork
- Vibration and temperature sensors to monitor bearing and fan health and prevent unplanned outages
- Proper installation and maintenance to ensure safe startup and operations