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Attenuation Of Air Intake Ducts on Process Burners

Attenuation Of Air Intake Ducts on Process Burners

Attenuation Of Air Intake Ducts on Process Burners

Hi, thanks for reading this post and I hope there is someone who can help me or point me in the direction of books I should want to read or web sites to visit. You can e-mail me information at Alex_Millington@mailcity.com. My project is this....

I have to look into the attenuation of Air Intake Ducts on Process and Power Burners in an attempt to reduce the noise levels recorded from 85dB'A' to levels of 65,70,75 & 80 dB'A' and suggest methods and materials and designs for these silencers... However I have little idea about acoustics or attenuation and I was seeking some advice. Basically what principles govern the design of sir duct silencers, how does the shape of the intake affect the noise produced, the length affect the noise produced, the size of the splitters between ducts and any other information that might be helpful...

All responses much appreciated....

RE: Attenuation Of Air Intake Ducts on Process Burners

The "Bible" on industrial noise control is "Noise and Vibration Control Engineering: Principles and Applications" by Leo Beranek (Editor)  I. L. Ver (Editor).  The list price is $190.   
Format: Hardcover, 1st ed., 804pp.
ISBN: 0471617512
Publisher: Wiley, John & Sons, Incorporated
Pub. Date: January  1992

There are useful chapters on what you are trying to do.

RE: Attenuation Of Air Intake Ducts on Process Burners

Any silencer manufacturer can help you with a selection or you can check the catalogs.  Your main problem is not the selection of the silencer but the allowable pressure drop which you can introduce into the system.  As a rule of thumb the higher the pressure drop the more the silencer attenuation you get.

So if you want 20 dBA reduction (your stated maximum), it may require depending on your flow rate and static pressure, and duct size, an increase in pressure drop which may affect the performance of the blower/fan.  Sometimes there is a margin in the fan performance which will allow an easy silencer addition, other times if there are a lot of bends, turns etc in the duct, the total pressure drop becomes a limiting factor.

Having said all that, it is possible to design or purchase a low pressure drop silencer.  It just has to be much bigger than a conventional silencer.

Another consideration is the frequency which you must attenuate.  If the blade pass frequency (number of blades x operating speed in Hertz) is low, you generally need a bigger silencer.

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