First, sorry by my bad english.
We have a problem with a ge hydrogen cooled generator 1GW the hydrogen consumption goes up and don't find the problem.
The normal rate of comsuption is a 1 pyramid of hidrogen (16 bottles) in 14 days and now we need 1 piramid for two days.

We found in past a high concentración of hidrogen in the pipe of vent separator chamber to the atmosphere and we decide setting upper the pressure of oil seals.

We checked the pipes, generator seals, etc... and dont found hydrogen leaks.
The current diferencial pressure hydrogen-oil setting in seals is around 10 psi and have a Flow of 18 gpm each one.

The purity of H2 it's correct and constant around 98%.

It's posible setting upper de oil pressure makes goes up the scavenging Flow and this is the problem?

Any solution? It's too high the settings of differential pressure?

Thans so much.

 

I would suggest performing a generator drop check first to verifiy the problem is with the generator and not the supply/distribution piping (any safety valves that could be leaking?).

Verify scavening flows are set correctly and the float traps are functioning as they should.

Higher seal oil flow would typically require higher scavening rates to maintain the same hydrogen purity - it could also allow additional hydrogen to become entrained in the oil.

 

We performed a drop pressure testing incomunicating hydrogen supply closing the last valve before generator, the pressure in the supply bottles not dropped and the side of generator dropped from normal pressure aproximately 71 psi to 68,3 psi in 9 hours, with this results clearly the problem is inside the generator or oil sealing system.
Thanks a lot.

 

Check your heat exchangers that cool the H2.

 

Check your heat exchangers that cool the H2.

Yes, I thinked that too, leakeage to cooling water through heat exchangers, its too dificult detect H2 in water but i think the efficiency of cooling would descend by the presence of bubble in tubes, but the delta temperature at heat exchangers not varied.
But, All is posible thanks

 

"What is the typical hydrogen usage for generation facilities?
The amount of hydrogen used per day is generally a function of the power generator capacity and the condition of the generators hydrogen seals. The higher the capacity, the higher the hydrogen pressure required for sufficient heat transfer.

Higher pressure results with higher leakage rate, requiring a higher hydrogen flow to maintain the pressure required for optimal heat transfer.

Generators in the 150 to 250 MW range coupled to gas turbines or the steam turbines of combined cycle power plants typically consume 200 to 600 scf/day (1 to 3 cylinders equivalent), (5 to 16 Nm3/day).

For generators coupled to steam turbines at thermal plants (coal fired or thermonuclear) power generators of 400 to 1,200 MW can use up to 1,000 scf/day (4 or more cylinders per day), (25 Nm3/day)."

So you are now experiencing a seven-fold increase in H2 consumption. The H2 is going somewhere, sounds like the safest advice is to put the unit in shut down and repair what ever has been damaged.

 

You say that you checked the pipes, generator seals, etc... , the "etc" includes the generator caps, from my experience we have encountered this problem.
The H2 cabinet (where the H2 analyzers are), have you verified that the purge flow is correct, not any open valve or solenoid valve that has remained open?