Hello Tech-City Guys

Mine is a small steam turbine that has deflectors on both bearings housings. But there is consistent leakage from both sides that has caused minor fires as well due to oil soaking in insulation.

Any experience of such turbines. Though recent machines generally have labyrinth seals but what should be done about it?

Any new solution for this? INPRO seal or ..?

Expecting great help.

A picture of your bearing housing with the deflector would be good to understand your problem.

What is the purpose of the deflector? Is this sleeve bearing?

For a fire to happen, there must be oxygen, heat and fuel. Air from the air. Fuel from lube oil but lube oil will burn unless the heat is so high to reach the flash point of the oil. Where did the heat came from?

What is the insulation material? Is it ceramic or rockwool?

Why did you mention labyrinth seal? The fluid is steam which not flammable although may be of high temp. What sealing do you have now?

Your bearings would be slinger ring lubricated with oil deflectors tightly fitted on to the shaft and running with it.

Check the oil level in the housing. If it is on the higher side consistenet oil leakage is hte result.

Inspect the steam end seals probably these are carbon rings seals.

Hi guys,
This is a sleeve bearing with sealing thru deflectors on housing ends. Oil Level is not a problem on this machine. Insulation is rockwool as is generally the case. I am opinion laby is good at sealing and containing oil. May be wrong?

Steam sealing is thru carbon rings which are source of heat. Are u people saying that steam is causing oil to boil off the housing?

What is the temp and pressuer of the steam?

Layrinth seal is normally selected for flammable and toxic gas ie. tightness.

Still cannot imagine your sleeve bearing set up with sealing thru the deflectors on the housing ends. Any sketches? What year of manufacture is this steam turbine?

The temp and pressure of steam are 370 degrees celsius and 38 kg/cm2.

Machine is about 30 years old.

DEFLECTOR.ppt (14 Kb, 58 downloads) DEFLECTOR

Inpro seal will be good idea. I know some applications, where it worked very well.

Make sure laybyrinth has return holes situated at the bottom, breathers / vents are not restricted.

dear Raj have u any experience with air ejectors for such applications?
Thanks

I think Logic has the right idea. I like Inpro too but others sold that are similar. Labyrinth seals are good and a variety is in the market place. One thing about any labyrinth seal, including the Inpro, if oil reservoir is over filled it will leak. Design will only handle a certain amount of return from the flow in housing.

yahoo, I do not know air ejector application in bearing housings.

In some cases we provided air purging in bearig housing so that steam does not enter bearing housing.

Air ejectors are also used in steam glands to remove steam leaked from shaft ends.

Thanks u all buddies.

Dear Raj could you please share some schematic of air purging and ejectors u have seen?

Hope you could do it...

Good day Gents,

In the facility where I work there has been the same type of problem: oil leak from the deflector. But also we have had some bearing failures which was not predicted with the vibration monitoring...

I am right now checking the past history of this equipment and I found two modifications: Air purge for the bearings and reduction of the oil pressure.

I was told that when the aux lube oil pump was running, the pressure reached 3 bars, so a modification was done to limit this pressure to 1 bar.

Actually before the normal oil pressure was 1.5 bars but now is 1 bar. This has eliminated the problem of oil leak but I am not sure if is causing the sleeve bearing to fail due to lack of lubrication.

Yahoo what is the oil pressure in your system?

Regards

Yahoo,

Are your sleeve bearings with deflectors like the set up in this pump which has an external and internal deflector rings?

http://www.hova.de/50.html?&L=1

What is the design pressure of the small steam turbine? Temp of steam?

This message has been edited. Last edited by: Josh,

quote:

The temp and pressure of steam are 370 degrees celsius and 38 kg/cm2.

The design of deflectors is different from the link shown by dear Josh. I have attached its drawing above as .ppt.

Hello all,
In the power plants where I work all of our turbine lube oil systems have vapor extractors. These small electric blowers pull vapors off of the reservoirs and vent them outside. They also pull a vacuum on all of the bearing housings because the oil drain lines are large enough to provide ample head space above the flow of return oil back to the tank. These oil drain lines form a completely closed system with the bearing housings, reservoirs, and drain lines under a slight vacuum. IF that vacuum is lost or reduced, the bearing housing seals leak. We have a water manometer on the reservoir to measure the vacuum provided by the vapor extractor. When the manufacturer was asked what level of vacuum to maintain on the reservoir we were told to keep it at a level that would keep the bearings from leaking oil. Normally we run a few inches of water vacuum. You might check to see if you have this kind of system on your turbine.

Guys
I totally agree with the comments made by Paul. In my experience, once we had oil leakage from the turbine bearings, due to a modification carried out on the discharge pipe of oil vapour extractor fans. The discharge venting pipe was facing the suction filter of air washer fan and hence there were some nuisance of fume smell in the turbine hall. To avoid this, the discharge pipe height was slightly increased, which resulted in the poor performance of the small fans mounted on the oil tank. It would be approprite to see whether your turbine has such mountings.

Yahoo,
Elliott have a similar deflector with slight labryinth in the center. We have installed air purge into the middle of the deflector (eg drilled into the housing between the inner and out disk). Air pressure 1 to 3 psi. We did this to keep moisture out of the bearing rather that stop an oil leak.
Note; air purge can also create leakage of oil mist out breathers etc.
We did try Enpro seals trying to stop the moisture, but ended up with oil leaks from them after any PM activites that required lifting the bearing cap only. To successfully reseal these you need to remove the rotor.
Another thing to check. If the edges/corners of the lab part of your deflector are not sharp corners, this can cause leakage. Someone may have kindly polished off or champfered the corners and created the problem.(its happened to me)

Deflector is provided so as to deflect the steam coming out of carbon rings in case of leakage.In bearing housing, labyrinth is provided so that oil may not come outside.If it comes out, it will be soaked into insulation & due to radiation, auto ignition takes place, reulting in fires.
For this, open the top half bearing housing, check the labyrinth clearances & if found higher replace the labyrinth.
If clearances are OK, check the drain holes in labyrinth at the bottom towards inside.If holes are chocked,cleaned it & if found OK increase the size of hole in labyrinth, so that oil may drained inside not outside.

We had some problems on a pump that had similar seals. The laby seals have small drain holes in the bottom. These holes on the old seal that were in the pump were very small. During one of our attempt to stop the oil leak we installed a new OEM seal out of our inventory. The new seal had drain holes more than twice as large as the original seal. The small holes would easily get blocked with trash. Another leak issue we have had on similar seals is craftsmen applying too much sealant to the joints between the upper and lower halves. The sealant would squeeze out into the labyrinths and block the oil that accumulated in the top half from getting to the drain holes.

quote:

These small electric blowers pull vapors off of the reservoirs and vent them outside

I think as Paul says I could try some air ejector on bearing housing to arrest the vapours.

As Watchorn says
if edges/corners of the lab part of your deflector are not sharp corners, this can cause leakage. I would be checking this in some opportunity.

But what min. clearance do you guys suggets?

And for arresting steam leakage from turbine packing rings, what should be done? May be Arvind have some idea?

Thanks and Regards to all.