GE Frame 9e Starting Air Booster Compressor Jam

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mechnub

I'm frequently experiencing failure to start the Gas Turbine on distillate fuel. It is mainly caused by the starting atomizing air booster compressor to be seized. After inspection of the compressor, we found out that there is water found in the pipings and has caused the compressor to jam (oil has turned into emulsion). My initial thought that It could be due to frequent online water wash that we usually do to increase the load during high temperature during the day.

My starting atomizing air booster compressor will always seize from operating because of the water that entered the atomizing air pipings has caused the compressor to jam. (is this valid?)

If so, how am i able to avoid such occurrence to happen again? As i know all the water wash provision valves have to be opened during normal operations. So is there any problems why the water wash liquid is able to enter the atomizing air line?
 
kwaku,

Use the Atomizing Air P&ID to troubleshoot the problem. There should be an isolation valve (typically solenoid-operated) upstream of the Booster AA Compressor, and a check valve downstream. The Booster AA Compressor should be physically above the Main AA Compressor which should make it even more difficult for water/moisture to get into the Booster AA Compressor.

There should also be low point continuous blowdown orifices in the piping to drain any condensate out of the piping (again--see the P&ID), which can easily get blocked/plugged with rust. If I recall correctly, there is supposed to be a continuous blowdown orifice at the Booster AA Compressor to drain water/moisture from the case. It, too, can get blocked/plugged with rust.

If the AA Precooler Temperature Regulating Valve (VTR2-1, if I recall correctly) is not controlling the temperature of the AS entering the compressors properly (and its quite frequently not--it's set too low, allowing moisture to condense in the cooler) then problems are going to occur. Full stop. Period.

<b>AND</b>, if you're using On-line Water Washing as a crude form of Power Augmentation then you're likely flowing a LOT of water through the axial compressor for much longer than intended--which is asking for Mr. Trouble to visit and leave gifts, maybe more than just this one.

On-line Water Washing is not an approved form of Power Augmentation. Opening manual piping drains while the unit is running and you're running On-line Water Washing is going to cause even more problems. On-line Water Washing was only intended to run for about 15-30 minutes. That's about all the stress the axial compressor can take on a weekly basis, or so. Running it for hours per day, day after day, is, well, begging for trouble.

If your management/ownership is hell-bent on continuing this practice, and you've proven the AA Precooler Temperature Regulating Valve is working correctly, you could install a manual shut-off valve upstream of the Booster AA Compressor to keep moisture/water out of the Booster AA Compressor.

ALWAYS use the P&IDs when trouble-shooting problems like this. Continuous blowdown orifices in piping low-points are misunderstood, and rarely checked for blockage/pluggage. And, using On-line Water Washing for Power Augmentation <b>IS</b> going to lead to problems--maybe really expensive problems.
 
A couple of things in retrospect....

The post should have been addressed to mechnub, not kwaku, who was spot on with the possibility of liquid from the AA Precooler.

Also, there was mention of an emulsion of oil and water in the original post, and it's not clear where that emulsion was found. It's possible that when the compressor was "jammed" because of so much water/moisture in the casing, the seals to the bearings/gears were damaged and allowed water into the gear box or oil from the gear box to enter the casing. There should be NO oil in the AA piping; if there is, that suggests something is amiss somewhere else. Possibly with the Main AA Compressor.

And, that's another odd thing--if there's so much water that it's inundating the Booster AA Compressor, why isn't that water getting into the Main AA Compressor suction and causing damage to the Main AA Compressor? The Main AA Compressor spins at a very high rpm (10's of thousands of RPM if I remember correctly) and water is NOT welcome in the Main AA Compressor!

Hmmm....
 
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