1 reply to this topic

[sgoel]

We have a diaphragm compressor on pure hydrogen service. We are facing a problem in operation.The compressor looses capacity suddenly. The discharge flow and pressure drops. This gets normalised by simply venting little bit of oil.

What could be the reason for this anomaly and what should we do to prevent this from happening.


Thanking you in anticipation please.

sgoel
india

[Nikhiln]

I must say these are just a couple of wild guesses. Feel free to discard them if you dont like the idea.

1) Maybe the high temperature is causing the oil to vaporise slightly, rather thermal expansion, I should say. This could expand the oil chamber volume, pushing the diaphragm further into the gas cylinder/compression area, reducing its volume (capacity). And when you vent the expanded oil, its back to normal volume.
2) Possibly, a pinhole has developed in the diaphragm, leaking oil into the compression area and reducing capacity.

I would think (2) is not very likely, since pure hydrogen and oil at high temperature are very unsafe. If this is really the case, I would think it is a very unsafe condition.

Remedies could be:

For (1) Check the oil properties for any changes/degradation it has undergone from its original specification. Any reason why it should be thermally expanding/vaporising? (assuming the compressor temperatures are normal and within limits)

For (2) Analyse a sample of the discharge hydrogen for oil. If there is oil, replace the diaphragm.

Cheers!

Edited by Nikhiln, 27 July 2010 - 07:50 PM.