Philadelphia boiler explosion

DanHolohan

At the district-heating plant.

http://www.powermag.com/boiler-explosion-shuts-down-philadelphia-chp-plant/

pecmsg

https://youtu.be/Jmg86CRBBtw

GreenGene

You have to love the professionnel spokesperson "experienced an eruption"

yeah that sounds nice, much better than explosion, no we didn't have one of those

DanHolohan

Audible ignition?

GreenGene

Wouldn't be surprised if it wasn't something like this, if I remember correctly they had an issue with the lwco and condensate pumps to one boiler, seems the lwco wouldn't turn the burner off and the pumps wouldn't refill the boiler so they were doing it manually while waiting for a part....???

What you'll see is a tech in front of the boilers and then he goes off, he notices the water level low in the boiler on the right and manually works the pump to add water to the boiler, the water level was lower than he imagined and he is lucky to be alive.

ahh the human factor

https://www.youtube.com/watch?v=fCej2OQSKnY

Steamhead

I believe it was John Mills who said the two greatest evils in the world at that time were intemperance and boiler explosions, and the latter was often caused by the former.

We don't know what happened at the Veolia plant yet, but I would not be surprised if it was found one of their people screwed up. We'd have to wait for an official investigation that was not tainted by corporate self-serving.

Boilers don't explode by themselves.

jumper

>>Boilers don't explode by themselves<<
I don't advise you to try to make one explode but I will say that it is not easy to do so.

ChrisJ

jumper said:

>>Boilers don't explode by themselves<<
I don't advise you to try to make one explode but I will say that it is not easy to do so. </p>

Sure it is.
Run it out of water with the burner running, wait a while and then feed water in it.

Pretty much guaranteed explosion.

It's a shame very few seem to realize how dangerous a damaged LWCO is.

Steam and water boilers are both extremely safe when the pressure relief and LWCO(s) are working properly. Damn near impossible to blow up.

I doubt any amount of pressure relief valves could ever stop an explosion due to dry firing and adding water though. That's just way too much all at once.

ChrisJ

Hatterasguy said:

ChrisJ said:

I doubt any amount of pressure relief valves could ever stop an explosion due to dry firing and adding water though. That's just way too much all at once.

I suspect the more likely cause is a loss of pressure.

Do you know what happens if a boiler at 300 psi suddenly loses pressure?

Have you ever done a blowdown of your boiler yet? Increase pressure to 12 psi and let it go quickly with the boiler drain. What do think happens to the instantaneous pressure inside the boiler? I have some proof as to what happens when the secondary manual reset pressuretrol trips at 15 psi and the boiler won't restart. ****.........why won't this boiler restart (scratches head)?

It stays the same until the boiler cools or water disappears?
I don't understand what you're asking or suggesting.

JUGHNE

I'll raise my hand and say that the remaining water, (there is probably a lot ) would flash to steam because of the pressure drop??

Robert O'Brien

BLEVE

JUGHNE

BLEVE also applies to propane tanks with fire under or near them. They have a relief valve riser pipe which usually ignites like a blowtorch. Makes it easy to find at night also.

I wonder which has the more explosive power.....500 gallon propane tank or steam boiler exploding? A lot of factors involved.

JUGHNE

A massive fire at an LP tank could occur if the overworked delivery tank truck driver drives away without unhooking his liquid fill hose during a busy irrigation season. (break away connections didn't work or somehow bypassed) Ignition source was probably the truck engine which ramps up to max RPM when inhaling LP or NG.
The end of the broken hose or pipe fueled the fire. The relief valve was cycling as the tank heated. The blow torch was being reignited each time. The 30 year old something volunteer fireman who crawled to the tank to valve off the broken pipe was asked by the TV crew afterwards "what was going thru your mind" as you crawled towards that valve, his reply was that he hoped the relief valve would continue to vent. There were several other bulk tanks (big boys) at this site, so it wasn't an option to let it burn out as would be the norm. The driver was the only fatality.
This happen a few years ago about 150 miles from me.

JUGHNE

Skit happens.....just like the guy who removes the manometer from the 1/8" port on the manifold of an LP furnace and as it fires again realizes that he did not put the plug back in the manifold. A real lesson in delayed ignition of having an extra large orifice in a bad place. It has never happened again. Ask me how I know. Stupid can be fixed if you live thru the lesson that was given.

BobC

We all make mistakes and some of them are bad ones; the key is not to repeat the same mistake. Besides there are a lot more you can try out.

Bob

ChrisJ

Wait a second,
The remaining water would only flash to steam as fast as you could drop the pressure. No?

In order for it to go above 12 PSI, you'd need to somehow bring the temperature above what it currently is, and that's not going to happen. It's not going to go above 422F because you opened a valve and the pressure will not higher, it's going to drop as things cool, perhaps not by much. Once the water is totally gone, the pressure should die off rapidly, almost all at once.


I must be missing something, because this example isn't working for me. We most certainly don't see exploding evaporators on air conditioners and refrigerators


Maybe I'm wrong, but this is how I see such a thing behaving.

Steamhead

HG is right. When you drop the pressure on water that is hotter than 212°F, it becomes "superheated".... hotter than would be needed to boil it at the lower pressure.

So, when the pressure drops, all the water boils.

Instantaneously.

Expanding 1700 times.

No boiler or pressure vessel can withstand that, so..... BOOM!

In the case of an overheated boiler, the first thing I'd do is shut off the power and the fuel supply.

Then I'd get everyone out of there. Immediately.

BobC

Many years ago I went down to the cellar of the 2 family house I was living in because of an odd smell. I found the side of the landlords boiler glowing cherry red so I killed it's power and disabled the oil supply so it couldn't refire. The sight glass was empty so I assume it lost it's water.

The landlord was some upset at having to replace his 40 year old Delco boiler and asked why I didn't just add water to it. I'm not the brightest bulb in the pack but I'm pretty good at smelling danger.

Bob

Jean-David Beyer

"Have you ever done a blowdown of your boiler yet?"

No, but I have seen it on a 150 psi locomotive steam boiler. One a lot like this:

https://upload.wikimedia.org/wikipedia/commons/c/c7/Southern_Pacific_Engine_9.jpg

Fascinating. I expected lots of superheated water (about 360F) water to rush out the blowdown pipe. My expectation was wrong, though. Just some steam (invisible) for a distance from the pipe then clouds of condensed steam. Noisy too. I think it was 2-inch diameter pipe. Probably a good thing it was not liquid water because with 150 psi steam above it, most of the water would have come out very quickly, but that is not how steam works.