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Anonymous Poster #1

Cause Of Sudden Jamming Of Steam Turbine Rotor At Barring Speed

08/07/2013 7:35 AM

we have two 250 mw steam turbine (BHEL make) unit. recently we are facing lot of trouble related to jamming of rotor when machine at barring gear. we have hydraulic motor operated turning gear arrangement at front pedestal. after normal shut down m/c put into barring gear automatically at 56 rpm. after 10 hrs when m/c is ready to roll (vacuum pulled and hp-lp bypass charged condition) we found rotor speed slowly decreased to zero. then hand barring started and continue till barring came again at hp shaft and casing temperature 290 deg C almost 48 hrs. please look into the matter and put your suggestion to overcome the problem. further more this situation happend three times in last one year.
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PWSlack
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#1

Re: Cause of sudden jamming of steam turbine rotor at barring speed

08/07/2013 7:38 AM

"Foreign contaminant!"

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RAMConsult
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#2

Re: Cause Of Sudden Jamming Of Steam Turbine Rotor At Barring Speed

08/07/2013 1:43 PM

Until you perform a complete internal inspection of both the turbine and the generator (they both have rotors) you have no way of telling where the binding takes place. There are many causes of this type of problem, but if it was working ok until the last maintenance shutdown then something was not done properly when the machine was reassembled.

Poor shaft/bearing alignment and/or bearing lubrication is indicated. If this occurs on both machines then it is most likely that whoever performed the last realignment followed the cold alignment procedures when the machine had not been idle long enough or followed the hot alignment procedures when the machine was at the wrong temperature.

You need to inspect everything related to the lube oil, barring gear, and shaft/bearing alignment. This not an experiment for the inexperienced, call the factory and pay for expert guidance.

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bigg
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#3

Re: Cause Of Sudden Jamming Of Steam Turbine Rotor At Barring Speed

08/07/2013 4:55 PM

Is this you again? http://cr4.globalspec.com/thread/62479#comment653427
Why are anonymous posts allowed?
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
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#4

Re: Cause Of Sudden Jamming Of Steam Turbine Rotor At Barring Speed

08/08/2013 3:19 AM

...then the cause is a failure to follow the advice in the earlier thread.

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dhayanandhan
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Engineering Fields - Mechanical Engineering - New Member

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#5

Re: Cause Of Sudden Jamming Of Steam Turbine Rotor At Barring Speed

09/09/2014 10:59 AM

It is possible,

1. that one blade might have dislodged from its position and trapped in the gap and got struck up.

2. the bearing might have got melted and seized.

Pl. inform this forum what was the problem and how sorted out.

DHAYANANDHAN.S
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bigg (1); dhayanandhan (1); PWSlack (2); RAMConsult (1)

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