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Reduce industrial stack discharge noise

Reduce industrial stack discharge noise

Reduce industrial stack discharge noise

(OP)
Looking for suggestions as how to reduce high velocity stack discharge noise without reducing the velocity.  Discharge velocity is needed to meet AAQS for dispersion.  Noise at property line is above maximum 60 dBA.

RE: Reduce industrial stack discharge noise

What are you discharging? Is it clean, dry, high-temp, etc.?

RE: Reduce industrial stack discharge noise

(OP)
Thanks dvd for your interest to comment/help resolve. To answer your question ----- Discharge is combustion exhaust from a 2,000kW peaking generator, #2 diesel fuel, 16" dia stack, 15,200 acfm at temp of 835 F.  Stack height is 35 feet and unit already has a hospital critical grade silencer.

RE: Reduce industrial stack discharge noise

How much attenuation do you need?
Do you have an enclosure on the genset?  What's the rating?  XXdBA @ X feet etc.
What's the rating (insertion loss) of the silencer?
How close are you to the air quality standards?
What's the set-back distance from the stack to the prop. line?

A 2MW genset, I estimate, to have an exhaust sound power level around 130-140 dB.  That's ignoring casing noise and radiator noise.

As well, if the numbers you gave are correct (i.e. the duct is 16" dia and flow is 15,200 cfm, that's a air velocity of ~10,000 fpm.  I'm amazed the silencer is working at those high velocities!
I'd imagine the self-noise would be horrendous, not to mention the material in the silencer won't last long.

A few suggestions:
There are outfits that can make low pressure-loss, ultra-high velocity silencers that may outperform the existing one.  
If you have the length (and other constraints allow for it), consider re-orienting the exhaust away from the prop. line.

Lastly,
You mention that you need the velocity due to dispersion concerns.  What dispersion model did you use? Can you use a more refined/advanced model? And I'm assuming your emission rates were based on manufacture's data, and not on emission factors.

-
Aercoustics.com

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