PSV Noise Attenuation Through Tailpipe 1

[KernOily]

Hi Guys. I have a PSV that will relieve 160,000 lbm/hr. Service is saturated steam of 70% quality. The PSV is located inside the plant limits. I can't move it outside the plant for a whole host of reasons.

The system design is robust and is fully designed against the need for the PSV. But, as they say, sh*t happens, and that's why the Code requires PSVs in real life. So I have to deal with the possibility of a high noise level during a relief event.

One solution is a silencer. Another soution is to pipe the PSV tailpipe/discharge pipe out of the plant to outside the plot limit and no silencer needed. My calcs show that I need to be 250' away from the plant, as the crow flies, to get the noise level down to the owner-mandated SPL (114 dBA at 3'). This of course assumes no attenuation caused by the long tailpipe. A diffuser will be installed at the end of the tailpipe to break up the velocity of the exit stream.

The question is, how much SPL attenuation will I get due to the 250' run of pipe? I have a hunch that I can get down to the required 114 dBA using less than 250' of pipe.

I searched the forum here but no luck yet. I haven't found anything in any vendor's literature yet either.

Thanks guys!!!! Pete

 

[ash9144]

I would not extend the pipe to off site. Always better to keep all your discharge points under your control. Also should something happen to cause a relief event it will not be steam being released but "smoke" at least to Joe Citizen and the media he contacts.

It is a little odd that you would worry about noise levels on a psv discharge. Should be a very infrequent event associated with some process upset.

I would use a silencer or different psv if it is truly necessary.

 

[vzeos]

I would be careful about making the tail pipe too long because this would tend to increase the built-up back pressure due to the resistance of the discharge system piping.

Take a look at this link for RV info:

http://www.tycoflowcontrol-na.com/ld/CROMC-0296-US.pdf

Here are some links on noise:

http://www.fisherregulators.com/tec...us/Use_of_Pipewall_Vibrations_d350411X012.pdf

http://www.fisherregulators.com/tec...amentals_of_Aerodynamic_Noise_d350491x012.pdf

http://www.atconoise.com/mediaroom/NOISE_HANDBOOK.pdf

 

[Process879]

since your are having high... flowrate... you need to consider the acoustic fatigue failure also in the PSV outlet line..

 

[MJCronin]

Kern,

Silencers built for steam PSVs are a mature, developed technology.

Your total cost for a properly sized silencer would be less than the 250' of piping plus the systems difficulties that would occur.

Try discussing your problem with these guys..... I have had good luck.... they are practical and smart....

http://www.universal-silencer.com/pdfs/HV.pdf

Be responsible and complete this thread with details of your final decision

-MJC

 

[KernOily]

Thanks MJ, will do.

Me? Responsible? Just ask my wife! Pete

 

[zerosum]

We used silencers on our cogen units to protect (actually, to mollify) the people off-site, not so much our Plant cadre. I don't believe we've ever had a demand since installing them.