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Can I get an accumulator to do this duty?
2

Can I get an accumulator to do this duty?

Can I get an accumulator to do this duty?

(OP)
Good afternoon all, I would like some advice on the possibility of using an accumulator or a similar device to deliver a process fluid when a plant trips, just enough to allow the plant to run down safely, probably on complete loss of power.  I need to deliver around 4 cubic meters of fluid into a pipe in a period of ~30 seconds at a pressure of around 30 to 45 psig.  I have a nitrogen accumulator in mind (or a few of them if one would be too large) as I have plenty of nitrogen to keep the accumulator pressurised.  Anyone seen anything like this before?   Thanks!

RE: Can I get an accumulator to do this duty?

It sounds like you know what you want.
Why don't you size it, and see if the accumulator size, and orficing seems reasonable?

RE: Can I get an accumulator to do this duty?

(OP)
Thanks, I wasn't sure if an accumulator of around 5 cubic meters gross, is a realistic device, I have only ever seen then sized for a few liters on oil systems.

RE: Can I get an accumulator to do this duty?

You could also use a tank on a tower, or a gravity powered accumulator.
 

Mike Halloran
Pembroke Pines, FL, USA

RE: Can I get an accumulator to do this duty?

There are several strategies that work for this.  You can size your nitrogen bottles (both pressure and volume) to be at 45 psig (or a bit more) when the gas has expanded into the volume occupied by the liquid (e.g., a 4 m^3 N2 accumulator at around 120 psia would be at around 60 psia if expanded to 8 m^3).  Or you can design the nitrogen for the maximum pressure readily available at your source and use a regulator to allow smaller bottles, etc.  All of that crap is just details.  The basic idea is sound.

I would build healthy safety factors into everything.  I'd probably store 6-8 m^3 of liquid and have enough nitrogen to dump the whole load and still be at 90 psig.  Make sure that your pipe is big enough to be able to satisfy your 30 second requirement.

David

RE: Can I get an accumulator to do this duty?

(OP)
Thanks very much for the thoughts.  It's obviously a custom design/build job, I'll have to think how we do this now.  Regarding a tower, I'm not sure we have anywhere high enough but it was something that had crossed my mind.  Thanks again, it's all useful stuff.

RE: Can I get an accumulator to do this duty?

This is not exactly the same, but it kinda is.  I've seem millions of gallons of fire water in tanks and man made ponds and diesel powered pumps sitting around for decades waiting for the call to action.

1300 gallons?  That's a medium size accumulator and it is very reasonable.
 

Good luck,
Latexman

RE: Can I get an accumulator to do this duty?

(OP)
Thanks a lot, I have discussed this in work today and first thoughts are that this is indeed a good solution to our requirements.

RE: Can I get an accumulator to do this duty?

If you use a gas filled/powered accumulator, make sure that it fulfills all legal design requirements which might exist in your country.

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