Very High Bearing Temperature (sleeve) for Single Stage Turbine

[Fay9al.]

Good days dears,

We are facing a real problem with a steam turbine as the bearing both ends getting heated so quick within few minutes after startup. The temperature is reaching and exceeding 120 C.

The bearings are sleeve type of bearings with oil sump and oil rings.

Several trial were made to reduce the bearing but non was good enough to run the machine longer. The bearing grade was changed from turbine 46 to 100, breather was added and extended, also the carbon rings were replaced by GTS.

thanks

 

[Tmoose]

History - used, new or refurbished equipment.
How are you setting oil level in the sump?

If new, what does the mfr have to say.
Was there an "event" that led to bearing replacement in-situ?
Was there an "event" that should have led to bearing replacement?
Have you inspected the bearings for signs of rubbing ?
A cross section of the turbine might be helpful. Are there more bearings deep inside the turbine?
What lubricant are you using now, and what were you using before the bearing heating began?
How are you measuring bearing temperature ? Are the probes new ? What is their calibration compared to the old probes?

 

[Fay9al.]

Thanks for the interest to help ... Here are some more information.

- The machine installed like 15 years back and never run since then.
- There were trails to start it but all were not successful mainly due to bearing temperature exceeding the ESD limit 120C.
- Then it was left for like 10 years or more without any trails.
- Last year, we start working on it hoping we will be able to run it normally
- First start was using the normal design with no changes: sleeve bearing, carbon rings, and turbine ISO 46 oil.
- We believe that the heat is transfer by conductivity from the steam through the shaft or the casing, hence the temperature start increasing once introducing the steam.
- Then we list a number of actions that might help like fitting the turbine with GTS seal, changing the oil to ISO 100, adding breathers ...etc. The temperature slightly improved specially at the beginning but it increases few minutes after the startup.
- The vendor after this year did not show an interest to support. His recommendation is to fit the turbine with forced lubrication system.
- INFO: the bearing temperature is being measure via RTDs.
- INFO: the bearings were replaced three or four times (two at the field and one during the upgrade to GTS.

Attached:
- Cross section drawing
- Picture

 

[stgrme]

Based on the photo in your latest post, it appears that the oil level may be set too high. The oil level should be set below the bottom of the shaft. If the shaft sits in the oil, churning of the oil due to rotation of the shaft will drive up the temperature of the oil.

If this is the case, I suggest you consult the operating manual for the turbine and the instructions for the oiler to determine the proper setting for the oil level.

Best of luck!

 

[Tmoose]

I am definitely not saying your oil level is not what the turbine manufacturer specifies, but here are some examples of oil levels with oil ring lubed bearings.

https://media.noria.com/sites/archive_images/Backup_200409_BlackOi-Fig1.jpg

https://upload.wikimedia.org/wikipe...er,_coloured_(Electrical_Machinery,_1917).jpg

https://www.educationdiscussion.com/wp-content/uploads/2015/04/Ring-Lubrication.jpg

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Figure 14 here suggests that excessively deep oil ring "submergence" can really reduce oil delivery at higher rpm.

https://oaktrust.library.tamu.edu/b...62544/PumpLecture6.pdf?sequence=1&isAllowed=y