Water boiler Internal explosion.

[tariq algerien]

Hello Everybody
A Buckling in smoke box doors occurred in water boiler as shown in the attached pictures
The service pressure of boiler is 11 Barg,the combustion occurred in atmospheric pressure
As per the pictures this problem seems to be occurred due accumulation of gas and burned in the same time creating internal explosion.
What the you think the rout cause of this problem is.

Regards

 

[DBreyer]

Multiple possible scenarios:
- The fire went out (maybe because of burner malfunction), but gas kept on flooding the furnace, then it either reignited on a hot part or someone tried to restart the burner without first ventilating the boiler
- have you checked your gas regulation valves? Maybe they opened too wide, allowing to much gas into the boiler
- same goes for the air registers. If they closed in service you get lots of unconsumed gas into the boiler which can ignite as soon as the air register opens again.

You should really check all monitoring you have on the burner system (e.g. oxygen in flue gas, position of valves, pilot burner function,..)and the components themselves (burners, pilots, air registers, valves,...)
Without more information it is all just speculation.

Daniel Breyer
Inspection Engineer

http://lnkd.in/dFcQA-w

 

[cap1a79]

One of the possible scenarios is "gaseous oxygen enhanced ignition combustion". (Referring to clause 4.2.20 of API 571)

Generally, while metals are not flammable, it becomes flammable in case oxygen content is more than 25 %.
To prevent it, the following points are recommended. (Reference from API 571)

I) Oxygen contents shall be below 25%. (For CS, even 15 psig of oxygen can induce this mechanism.)
ii) Velocity shall be below 30 m/s.
iii) Must be clean (No oils or greases)
iv) non-metallic, Al, Ti shall not be used.
v) Susceptible point --> The portion where there is transfer from high to low pressure. (adiabatic condition)





Lee SiHyoung,
WorleyParsons Oman Engineering,

 

[DBreyer]

gaseous oxygen enhanced ignition combustion sounds highly unlikely to me.
Where would the oxygen content >25% come from?
Typical boilers are operated with air (21% O2). I have never seen a boiler operated with pure oxygen.


Daniel Breyer
Inspection Engineer

http://lnkd.in/dFcQA-w

 

[cap1a79]

Thanks for the interest. I would kindly share the detail as below.

The usage of oxygen en-riched(>25% O2)combustion air is to increase yield of by-product. There was a report (whose title is "Enhancing SRUs with oxygen-enriched air") and it proves that there is increase of yield when using O2 en-riched combustion air (ex., 26%, 35% O2 air) instead of normal combustion air (21% O2)
Also, if you search thru google, you can find the cases for boiler as well. The below path will be one of the examples.

https://www.google.com/url?sa=t&sou...FjABegQIDRAE&usg=AOvVaw1dMP0T7t1g77F7_vhBS_nW

Anyway, what I would focus on was the level of oxygen whether it is 25% or not. If not, the mechanism will not be applicable.

Lee SiHyoung,
WorleyParsons Oman Engineering,

 

[chicopee]

Improper purge cycle?

 

[hacksaw]

my experience as well, with a 6 fuel boiler (recycle gases), extensive pre-lighting of the combustion chamber is manditory, we were lucky, it was only a "puff" but with the fire wall puffing neary 150 mm, before falling back, we only has 1 m operator platform, with a 3 m drop,

Extended prefiring purge,
introduce pilot gas, ignite,
increase combuation air flow
introduce main burners one at a time, and only ignite one burner at a time
bringing it up

purge, purge, purge, the combustion chambers are well known to accumulate gas pockets,

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