Turning a large vertical generator rotor to horizontal 1

[edison123]

We want to tilt a 100 ton vertical generator rotor to horizontal position by placing it on 40 inch x 40 inch x 40 inch rebarred concrete cube.

The rotor will be hung from a crane at the top and it will be turned on its coupling flange (sitting on its edge on the concrete block) till it is horizontal.

Will this concrete cube hold the 100 ton weight ?

What I am worried about is the pressure at the point of contact of the coupling flange with the concrete block. The whole weight, at least for some time, will be concentrated at this line contact.

I have posted this in civil engineering forum also to get additional inputs.

 

[itsmoked]

I think the bigger problem is not the weight bearing question but rather the pounds per square inch at the edge of the flange when the rotor is between about 30 to 50 degrees over from vertical. You will probably have over a million pounds per square inch at the contact point with the block. This might cause an immediate plunging crack across the block.

If you could protect the top of the block with something like a another steel cap plate or better yet some sort of fixture that mates with the flange and rotates with it, that would be better.

Also the strength of that block is entirely dependant on the quality of the concrete... It varies widely! Is it 3 sack or 5 or 7 sack? Is it fully cured? Was it part of the facility? Is there some record of the facility's concrete specification? This would help in estimating its load carrying ability.

 

[edison123]

Thx itsmoked. Yes, it is pressure at the contact point that gives me the nightmares.

There is a L shaped fixture that is bolted to about 20% of the coupling flange rim. It is in intimate contact with the arc of the rim

I don't have the specs for the concrete block but it has been used to rest a 60 ton horizontal rotor in another power station.

The OEM had originally provided a tilting stand made of layers 10 inch square wooden sleepers assembled and braced with angled ties. Over the years, the station has sold it off as surplus material (some bean counter's work there).

 

[itsmoked]

Sorry bout that bean counter.. I used to see that at my job... An idiot bigwig would come thru spouting that every square foot of facility had to earn us $30/year and that this and that sitting in storage was obviously not earning "anything" so out it goes....

Sounds like that L fixture has a flat side to it which would help a whole bunch.

I'd also suggest that if you can make the metal cap actually cover the concrete block it wouldn't matter how poorly it was constructed. It could turn to dry sand and still provide all the compressive strength you need!

I noted in the CE answers, wood. I would still be very nervous about the unconstrained base of the rotor kicking out once it was leaned over far enough. This would probably be a disaster to the rotor and probably the crane too, since it would involve sudden loads in unpredictable directions.

I would add a short raised steel box that the wood dropped into and was then laterally constrained by. Of course the same goes for the steel. It would be an upside down box dropped over the block so it can't shoot of to the side.

Good luck. You should take pictures!

 

[BJC]

The type of support may not matter. Have you considered or ask the manufacturer if the rotor can be stored in the horizontal position? You could wind up with a bent shaft.
Bearings on vertical shaft units are not made to take a lot of side loading.
If the buy is worried about space build a proper stand and store stuff under the poles.

 

[itsmoked]

Hi BJC; edison123 notes (in his last post) that they had a stand specifically for laying over the rotor. I presume he only wants it over to service.

 

[edison123]

A little bit more about what we are doing here with this monster.

This is a 50 MW, 600 RPM hydrogenerator with what is called "combed construction" for the rotor poles. The rotor poles have a comb at the pole shank, which fit to corresponding grooves in the rotor rim built of circular plates. It is an odd and not widely used design but a must for high speed (???)hydro machines of 600 RPM and over.

We need to rewind the rotor (i.e. replace all the pole coils) as part of life extension. To take the poles out and fix them back, the rotor has to be horizontal.

The most risky (or is it riskiest ?) part is the turning the rotor vertical to horizontal and then back to vertical.

itsmoked:

Yes, I plan to use a 1/2" steel plate and a 10" wooden block and tie them altogether to the concrete block with angled braces. Thx again for your word of caution.

I will definitely post the pictures here and the CE forum.

 

[MikeHalloran]

I'd try to duplicate the OEM wooden stand, and make sure the bean counters get the blame for the size of the bill.



Mike Halloran
Pembroke Pines, FL, USA

 

[rmw]

Bean counters never take the blame for anything. They will just pay the bill and then charge it to edison123's budget.

rmw

 

[BJC]

I witness a rotor for a high speed generator being moved around once. It was a long rotor and was being machined or something in a vertical lath ( or something, what I saw was incidental to another job).
If your still not sure go find someone from the generator buidling industry and hire them as a consultant to design any cradles or sturctures you need and write the proceedure for turning it.
There got to be a few people left upstate New York or St Cloud MN that know the ropes.
This is a case of good engineering being the cheapest thing you can buy.

 

[edison123]

Mike

Yes, I have advised the client to go in for the OEM supplied wooden stand immediately. I have got 2 more units to handle this year. But given the time pressure for this unit, I am forced to use the concrete block with some modifications suggested by some good people here and CE.

rmw

It ain't coming out of my budget. 'You lost it, you pay for it' is my motto.

BJC

This is a project in Malaysia. I have turned such monsters on their heads before. Only, in all earlier cases, it has been wooden stand.

 

[MikeHalloran]

A really good crane operator can surely rest the rotor on one block and rotate it to horizontal without tipping or sliding the block. Not all operators are that delicate.

Just as insurance, I'd add padeyes to the sleeper cage near the top, and chain it to something immobile.




Mike Halloran
Pembroke Pines, FL, USA

 

[byrdj]

Is the notch in the two center sleepers for the L bracket bolted to the rim. I noticed it is off center. besure it allows distance for work needing to be performed

 

[edison123]

Mike,

The crane operator is very good (30 + years of experience).

The opposite end (right side of the block) will be anchored at the floor level to nearby wall by 10" sleepers.


byrdj

The rotor will be toward the left side of the block. The rotor when horizontal will be away from the block on the left side of the picture. The notch is cut 300 mm away from the left edge.

 

[itsmoked]

Forgot the 400X450 admonition didn't you.. hahaha

Looks good to me... Do I see another "Block unit"?

 

[edison123]

itsmoked,

you got me.

Yes, there is another block to support the other end.

In another two hours, the trial is on.

Wish me luck.

 

[byrdj]

Luck.

Will we see photos of the lift and turn?

 

[edison123]

To all the MVP's here

We just now turned the rotor. No problems except some wood crushing.

Will post the pictures shortly (this time I'll be careful to reduce the size)

 

[itsmoked]

Glad that's all that got crushed...!

 

[edison123]

Yeah, tell me about it.

I just now put the pics in the CE forum (I didn't want to add to my ineptness further here in EE forum).

Thx itsmoked for your valuable tips.

I apologize to the thread viewers for the large pictures here. It is the one point of itsmoked's excellent faq I missed.

I have already RF'ed that post.