Acoustics for Thermal Power Plants

Aerodynamic Silencer for F.D fan

Noise solution for F.D fan

      In power station, boilers (steam generators) are fired with oil and water tubes extending through the boiler containing water being heated by means of suitable air heaters. Large amount of combustion air can be provided to these air heaters by means of a forced draft (F.D fan) fan unit. The fan unit is powered electrically and can be arranged to rotate about horizontal axis. It is known to deliver fresh air from the atmosphere through a long, vertically extended air duct that may include a splitter-type sound attenuating section.

      The existing splitter arrangement at the inlet of the duct occupied more than 50 % of the frontal area. The splitters are lined with suitable attenuation material like fiberglass batts, mineral wool etc. Inspite of attenuating noise, this arrangement giving much pressure drop across the length so concentration was focused on to reduce the pressure drop while maintaining the noise level same or reduce to some level.

      mech-well provide the aerodynamic design of duct, which is able to reduce pressure fluctuation (responsible for noise generation), turbulence and avoid boundary layer separation. The following two figures are showing existing arrangement of FD fan inlet duct with contours of Total Pressure and Sound power level (SPL) respectively. SPL contours figure is showing the noise source locations, which is useful for further improvement of design.

Existing FD fan Inlet duct with contours of pressure

     Existing FD fan Inlet duct with contours of Sound Pressure Level showing the different strength of noise source Results we got from our modifications:

a) Reduced pressure drop after modification.

b) Attenuation of noise up to the standard recommended by OSHA.

c) Uniform distributed flow along the duct.