Tagged With "600gas"

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Unexpected high vibration sgt 600gas turbine

aziz58 ·
Dear all I face to strange behavior vibration of gas turbine.sgt 600 is double shaft gasturbie. Compressor turbine and power turbine. Compressor turbine consist two journal bearing .operational speed is about 10000 rpm for compressor turbine and 7500 rpm for power turbine. Alarm limit is 7 mm/s and the trip limit is 15 mm/s .we have just one accelerometer on the casing near the bearings for measuring and monitoring. overal vibration of both bearing of compressor turbin increase by the same...
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
Did you restart? How old is it? Have you stable brg. temp and pressure? Any other none normal happenings? Have you inspected mounting of the machine to the foundation? I have another AFAIK unsolved case same machine elsewhere where inspection gave the same result but it create a vibration of the same freq. on all bearings that seem to be unrelated to any speed or other so it would be likely a resonance that is excited from something but your machine seem to have a "better" vibration picture...
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
Thanks dear oli Temp and pressure are stable.phase vibration is constant .we start more than 5 time at different days. sometime we find the turbine 2 days in service with out increasing vibration. But after shutting down and starting at another day we face to unexpected behavior . Thanks in advance
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
The age of machine is 3 years
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
Yes, the shutdown is normal . At the starting vibration increase at bearing of compressor up to alarm limit but vibration of turbine is good. By passing the critical speeds ,vibration of bearing of compressor decrease but at this time beaing of turbine increase to alarm limit(7mm/s). After that by increasing a little speed of power turbine ,suddenly vibration of bearing of turbine reach to 15mm/s(trip). Age of machine is 3 years .bearing wasn't checked until now . Best regards
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
So shutdown is normal part from where it trips? Would the vibration be high from start when having a bad start or when do it increase? How old is it? When was bearings checked last time? Can you take a look at the mounting of the machine so nothing misbehave?
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
Did you restart after the event? If so how was that? Has this only happened once? How much speed increase about was it for the PT?
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
Yes we start after event ,vibration some time increase earlier or later . Compressor ideal speed is around 9600 rpm and the pt speed for that is 7300 rpm. By increasing the pt speed to 7500 event will be occur
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
OEM ask to open the upper casing to inspect all internal parts . But we hope find the root cause of this event
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
Is it reproducing every time you increase PT speed that hi?
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
You can and have reproduced it? What does the OEM say?
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
Re: Unexpected high vibration sgt 600gas turbine
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
Yes. We have started more than 5 times. All test lead to trip by reaching to 7500 pt speed
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
I know it was not my question, did the trip repeat more than once?
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
Ok,do you have a SSS coupling btw. PT and generator? Have you checked it? I expect you have cleaned the PT rotor?
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
We have flexible membrance coupling
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Re: Unexpected high vibration sgt 600gas turbine

aziz58 ·
No, because we don't have high vibration on bearings of pt .and as l mentioned there is double shaft so no connection between compressor turbine and power turbine
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
Did you inspect it for cracks or deformation?
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Re: Unexpected high vibration sgt 600gas turbine

OLI ·
The other machine always get good after cleaning, any similar effect of that here?
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