The alternator

[Besoeker]

I was due to go on my "holidays" later this year to get a bit of sun and sand - no, not the beach, the desert.

The trip was to commission a new static exciter for an existing 30MVA alternator. The alternator is driven by a gas turbine.
Unfortunately, the turbine had a bit of a mishap. The rotor lost a few of its blades....



Luckily, they were found - lying in the bottom of the stator.....





Luckily, they were found - lying in the bottom of the stator.....



I have a notion that maybe they won't be getting glued back on.

 

[texie]

Gee, looks kind of catastrophic to put it mildly. Looks like a case of 1 blade failing and becoming a battering ram and then the domino effect takes over. Must have been quite a racket. Somebody is going to have to get their checkbook out.

 

[Besoeker]

Gee, looks kind of catastrophic to put it mildly. Looks like a case of 1 blade failing and becoming a battering ram and then the domino effect takes over. Must have been quite a racket. Somebody is going to have to get their checkbook out.

Terminal, I would have thought. No pun intended.
The failure was on restart after having been idle for some time. Maybe it was bearing failure resulting in contact between stator and rotor.

 

[zbang]

IIRC, turbines often have a jockey motor slowly turning them when not in use to keep the shaft from sagging. There's even the possibility of some fluid in the feedline. Looks like a bad day for everyone.

 

[eHunter]

Terminal, I would have thought. No pun intended.
The failure was on restart after having been idle for some time. Maybe it was bearing failure resulting in contact between stator and rotor.

Just looking at the images is painful.
Good thing is that it did not self destruct while you were performing the commissioning. :angel:
Do you know if a fault analysis will be performed?

 

[Sahib]

I suspect more of poor workmanship than of defective material: even helicopter rotor blades are fixed with suitable adhesives.

 

[Besoeker]

I suspect more of poor workmanship than of defective material: even helicopter rotor blades are fixed with suitable adhesives.

I suspect you are incorrect.
It had been in operation for about 40 years.
And made by one of the most reputable manufacturers in the world.

 

[Sahib]

I suspect you are incorrect.
It had been in operation for about 40 years.
And made by one of the most reputable manufacturers in the world.

Then it is a case of fatigue. Better try to furnish a little more details in the OP or clearer heading next time.

 

[Besoeker]

IIRC, turbines often have a jockey motor slowly turning them when not in use to keep the shaft from sagging.

Yes, I've seen that and heard of it sometimes referred to as a Sunday drive. Such things are also used in paper mills on Yankee cylinders.
I don't want to go into all the history but it is in a part of the world that got pretty hostile for a while and maintenance and operation crews were evacuated.

There's even the possibility of some fluid in the feedline. Looks like a bad day for everyone.

Expensive, whatever.

 

[Besoeker]

Just looking at the images is painful.
Good thing is that it did not self destruct while you were performing the commissioning. :angel:
Do you know if a fault analysis will be performed?

It may already have been. I'll nudge my contact on site to get an update.

 

[K8MHZ]

Is that a steam turbine or a gas turbine?

It looks like a steam turbine to me, but you mentioned that the generator was powered by a gas turbine. The only time I have seen gas turbines power steam turbines was in a heat recovery steam system which I don't think was in use 40 years ago.

 

[Besoeker]

Then it is a case of fatigue.

I'll pass your professional conclusion on to our customer.
They may wish to engage your evident expertise.

 

[Besoeker]

Is that a steam turbine or a gas turbine?

It looks like a steam turbine to me, but you mentioned that the generator was powered by a gas turbine. The only time I have seen gas turbines power steam turbines was in a heat recovery steam system which I don't think was in use 40 years ago.

It's a gas turbine.

 

[eHunter]

I'll pass your professional conclusion on to our customer.
They may wish to engage your evident expertise.

:lol:

 

[eHunter]

Then it is a case of fatigue. Better try to furnish a little more details in the OP or clearer heading next time.

Or any number of other causes... including, but not limited to:
FOD, DOD, harmonics, heat erosion, suphur or salt damage(not likely in desert), nozzle damage, overload damage, surge damage, thermal stress, vibration, flutter, aerodynamic excitations, suphiidation, failed bearing(s), embrittlement, fretting and many, many more.
It coiud possibly be fatigue related failure or any other singular or combination cause.
We don't know and I doubt that you know unless you were there and personally introduced the FOD, then you would know the root cause.

 

[Besoeker]

Or any number of other causes... including, but not limited to:
FOD, DOD, harmonics, heat erosion, suphur or salt damage(not likely in desert), nozzle damage, overload damage, surge damage, thermal stress, vibration, flutter, aerodynamic excitations, suphiidation, failed bearing(s), embrittlement, fretting and many, many more.
It coiud possibly be fatigue related failure or any other singular or combination cause.
We don't know and I doubt that you know unless you were there and personally introduced the FOD, then you would know the root cause.

Quite so.
During the course of making one of my posts I interrupted my eloquent flow to send an email to my site contact.
We are on very good personal terms and we exchange some experiences unrelated to business. Like our five year old grand child faaarting and blaming it on her little sister. You'd have to have been there....

I've no doubt he'll give me an update. More relevant to the truly terminal turbine than the wee girlie's genuinely gratuitous gaseous gifts....

 

[Sahib]

It is just brainstorming that is all we could do here for even the OP is not sure of what really caused the turbine damage despite being reportedly at the site.

What is annoying is the OP did not try to choose one best idea out of the brainstorming so far carried out to try to correlate with the true cause but made fun of those who tried ( contrary to the spirit of brainstorming) such as

I'll pass your professional conclusion on to our customer.
They may wish to engage your evident expertise.

 

[GoldDigger]

It is just brainstorming that is all we could do here for even the OP is not sure of what really caused the turbine damage despite being reportedly at the site.

What is annoying is the OP did not try to choose one best idea out of the brainstorming so far carried out to try to correlate with the true cause but made fun of those who tried ( contrary to the spirit of brainstorming) such as

I don't see that the OP ever asked for brainstorming about the cause of the failure, he just posted some neat pictures.

 

[topgone]

Terminal, I would have thought. No pun intended.
The failure was on restart after having been idle for some time. Maybe it was bearing failure resulting in contact between stator and rotor.

I am wondering why the operator proceeded starting the unit without listening for rubs during barring gear operation. In my younger years, I had the chance of reviving a 15MW, single-shaft, 3600rpm gas turbine and we made sure all the bases were covered before we started the unit: lube flushing, combustor draining, air filter replacement, bearing oil pump/ emergency bearing oil pump/ shaft lifter pump testing, etc.

Your pictures also looks to me like a lot of sand caused fouling on the compressor side.

 

[Besoeker]

It is just brainstorming that is all we could do here for even the OP is not sure of what really caused the turbine damage despite being reportedly at the site.

What is annoying is the OP did not try to choose one best idea out of the brainstorming so far carried out to try to correlate with the true cause but made fun of those who tried ( contrary to the spirit of brainstorming) such as

Why? It isn't my turbine.