Help with High High Pressure Boiler Pop Safety Valves

RayWohlfarth

I can really use your help here. I visited a facility that tests pop safety valves up to 1,500 psi. Yes, it was a huge adreneline rush. They want a way to blow down the steam pressure when the test is done. They do not want it blown outside as the boiler room is in the front of the building and think the water will land on everyones cars. They have a pipe into an underground concrete pit and the steam is destroying the concrete. Someone suggested filling the pit with gravel. Any ideas? Thank you in advance. This one is a weird one.

ethicalpaul

Fill the pit with water? Guess that'd be noisy. Maybe run like a misty waterfall to shoot the steam into.

Intplm.

@RayWohlfarth Many of the power plants that I have worked in have piped there relief valves through the roof.
They could have the discharge piping at different heights above the roof serving the different discharge ratings.
Of course they would have to pipe it in a safe place away from people and property to prevent injuries or damage of property.
Have them check out what some power plants do and go from there.

Jamie Hall

Through the roof makes sense, but a water quench system could be created with some thought which would be quite quiet... use the escaping steam to pull water into a larger pipe, somewhat along the lines of the steam injectors used on big steam engines (go talk to the men at the Union Pacific Railroad shops in Cheyenne for suggestions!) could be used.

RayWohlfarth

Thanks @ethicalpaul I was afraid of condensate induced stare hammer but that may work
@Intplm. I suggested that and they were afford neighbors would complain LOL
Thanks @Jamie Hall It makes a loud howling when open My spider sense was tingling

Intplm.

Done correctly. The neighbors may never even know it is happening.

I suppose it must have a lot to do with the location and piping of the discharge. Maybe put in the discharge pipe and see if there are any complaints ??

Another thing to do it use a large well vented metal tank. Have the relief valves discharge into the large tank or tanks. Then have the tanks vents go through the roof, dissipating the steam. That should help to lessen any neighbors complaints.
This might be similar to what they have now but should not deteriorate like the concrete is. Of course condensate will build up in the tanks and have to be pumped out.
Seems like a large condensate return tank with pumps , pumping the condensate away might do the trick.

ScottSecor

Some of our larger commercial customers with steam plants use something like this:
https://www.bryanboilers.com/pdfs/Boiler_Blowdown/BDS/Form_7000.pd
This may be a better link:
https://bryanboilers.com/boiler-accessories/boiler-blowdown/

Our customers with full time operators would typically blow down steam boiler low water cutoffs into these devices. The steam would change state to hot water, get mixed with cooler water and end up in the sump pump pit. Ultimately the sump pump would pump the "cooled" liquid to outside.

Intplm.

Boiler blowdown systems sounds like the answer than ??

EBEBRATT-Ed

A boiler blow down system is for blowing down water from the boiler that will flash into steam. Most any manufacturer of HP boilers will have a system available. You pipe city water to it to cool it before it goes to the sewer. The system has a temperature regulated prv so when it senses temperature above set point it feed cold city water

If you are blowing the steam off I would go through the roof. I beleive the pipe must be 7' above the roof (or higher) so no one gets burned. They usually go through the roof vertically up 7' put a 90 on it then a 2' nipple with the outlet end cut on a 45 (whistle cut) I think it is in the ASME Code

Intplm.

@RayWohlfarth I believe that, and from what is being discussed hear, you might be looking for something called a "surge tank".

Surge tanks have different applications and might be what you are looking for.
Maybe check out Cleaver Brooks, or Shipco companies. And the company @ScottSecor mentions. They can probably recommend something to meet the relief valve test facilities needs.

RayWohlfarth

Thanks @Intplm. and @ScottSecor I will be looking into one. I have not found one which can handle pressures as high as 1500 psi
@EBEBRATT-Ed I will check into that code Not sure it is Section IV Thanks I have my homework to do. I appreciate you pointing me in the right direction

coelcanth

too bad they have to waste all that good steam...
they should route it through a turbine and power up some batteries !

ScottSecor

Ray, just our of curiosity what are they using to generate 1500 psi steam pressure, small electric boiler? What kind of pipe do they use for pressure that high, XXS or something else?

ethicalpaul

coelcanth said:

too bad they have to waste all that good steam...
they should route it through a turbine and power up some batteries !

Yeah, or heat up a pre-heat tank for the building's hot water

RayWohlfarth

@coelcanth Yes They thought about a coven plant but it would not pay for itself
@ScottSecor They have a once through vertical boiler I cannot remember the name of it
@ethicalpaul They already do that but 1500 psi is a deal breaker for installation I think

SlamDunk

Let me get this right, they test their steam system safety relief valves by running boilers up to 1500psi (set point for relief valves) Then they want to open a vent valve somewhere safe and sound until they return to normal operating pressure of steam system...

What is the normal operating pressure? How often do they do this test?-if i have it right

It takes me hours bleed from 100psi to zero through a four inch roof vent. I dont go full open right away- it is loud and rains.

ScottSecor

SlamDunk, I'm only guessing here, but I suspect the boiler for the pressure tests is relatively small. In my mind, it would be impractical to heat up a typical 500, 200 or even 100hp steam boiler up to 1500 psi just to test the opening point of a new or rebuilt relief valve.

I would expect them to get the boiler to 1500 psi and test a bunch of valves set for this pressure. Then test the 1000 psi valves after dropping pressure. Then 500 psi valves and so on. I'm sure Ray or someone else can conform this.

SlamDunk

ooooh! I understand. I read it wrong. So it is a facility like Kunkle Relief & Safety, that rebuilds, tests, and re-certify's relief valves!

Got it.

I would think a vent submerged in concrete pit filled with water would work.

An old timer had to run 50 psi steam into a plastic garbage can filled with water for an hour when we added on to our system. It was a low rumble. He called "steam thumping" and explained the thumps were caused by steam collapsing into condensate. Just had to remove water every so often. There was no splashing. The can didnt melt. It was fascinating to watch.

RayWohlfarth

@SlamDunk and @ScottSecor That is exactly what they do. The 1500 psi is used on the power plants When I was there they tested a 400 psi and it tested the old sphincter muscle
@SlamDunk Someone recommended filling the pit with rocks. I am a bit hesitant about using water so it does not have that steam induced water hammer
Thank you gentlemen

mikeg2015

Could you run it through a regulator, drop it to 2psi and use a air cooled heat exchanger? I think on power plants they call these “fin fans”.

Best way to drop steam pressure and volume is to cool it.

Could also use a heat exchanger that preheats boiler feed water to a storage tank and save the energy.

RayWohlfarth

@mikeg2015 They are preheating the boiler water I like your idea Thanks

EBEBRATT-Ed

@RayWohlfarth ,

Don't think rocks are a good idea. Some rocks absorb water like a sponge. I have herd about people throwing rocks on a camp fire and the rocks explode because of the water-steam change.

Bad steam in that case

RayWohlfarth

Thanks @EBEBRATT-Ed I remember that from my camping days but forgot