Compressor fuel gas and/or start gas 1

[engr2GW]

Hello,

When a compressor goes down or stops running, it seems the fuel gas or start gas continues to flow, does the compressor have an inbuilt system that stops taking the fuel gas or start gas? Some other engines have fuel injection systems that are run by the running of the engine (or part of it), but the fuel and start gas of a compressor is supplied (typically in the oil field) by an external source, usually gas from the facility the whose gas the compressor is compressing.

So apart from designing the fuel gas header to shut in when the compressor stops running:
1. Are there compressor system that ensures that no more gas intake happens when the unit is down?
2. If not, can continuous gas flow into the unit cause fire or other problems?

Thank you.

As much as possible, do it right the first time...

 

[1503-44]

It is prudent to put an automatic shut in valve on the fuel gas system piping somewhere, either at the fuel gas takeoff from the main gas line, or outside the compressor unit area, or building housing compressors. It can also be helpful to have a manual, locked closed, bypass valve there to be used for black starts.

Compressor stations should also vent all gas to a safe location in the event of an ESD situation.

 

[engr2GW]

Thank you 1503-44.
What (if any) are possible problems with continuous flow of fuel gas if the engine is not running?

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[LittleInch]

Most gas turbines, which is what I think you're talking about, but you use the term "compressor" a bit loosely should have a shut off valve within their system. How else do you turn off the gas turbine??

Or do you mean a gas engine / reciprocating engine?

Please explain the sentence "it seems the fuel gas or start gas continues to flow". This doesn't make sense.

But you really don't want gas going places it shouldn't. Just solve the problem if there is one.

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Also: If you get a response it's polite to respond to it.

 

[engr2GW]

Thank you for pointing that out LittleInch,

Yes, you are right, I am referring to reciprocating compressors used in the oil field.

I agree that there should be independent shutoff system outside the compressor. I was asking if there is something similar in the compressor and if there is any serious danger if the unit is not running, does it just meet a dead end and stays until the next blowdown and startup or...

About my statement "it seems continuous to flow", that should have been a question mark, does it continue to flow or does it mean a dead end.

Thanks again.

As much as possible, do it right the first time...

 

[LittleInch]

Ah ok, that makes a difference, but I'm still not clear about your question I'm afraid as the OP seemed to talk about both compressor and engine in the same sentence.

But assuming you now mean only the actual gas compressor, then it shouldn't make a big difference.

Most piston type compressors will in effect act like a non return valve, but the potential issue is that gas will leak backwards through the compressor due to leaky valves or leak out through seals in the machine.

Also if for some reason the pressure drop was negative then gas can flow through the compressor from inlet to outlet.

But if the outlet pressure remains higher than the inlet pressure then gas will not flow through the compressor when it is stopped in the "normal" direction.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[engr2GW]

Thanks for the points LittleInch

To answer your question about engine or compressor, I was not referring to the process, I was referring to "fuel gas" shut off, so yes, the engine.
I agree that the problem should be minimal in the compressor itself.

As much as possible, do it right the first time...