One of our gas turbine GE Frame 5 has a problem of high oil consumption. The oil mist from the console is being vented to the atmosphere where due to excessive amount, it is showered all around.
I installed a pressure gauge that measured a positive pressure of 28-40 mm H2O in console.
What could be the causes and any remedial action?

I guess you are talking about turbine oil.

What is the oil operating temperature? Is cooling sufficient?

Yes Josh,
its turbine oil. Caltex Turbo46.

Its temp. is generally around 65 degree Celsius. Its cooling is not a problem.

I was wondering what could have caused that increase in console air pressure. Because the sealing air is coming from Orifice though the comressor discharge may increase in winter.

Thanks for consideration.

Have you contacted the OEM about this problem?

Yeah Josh,

But OEM is just studying it for couple of weeks.I need some immediate cause and solution to combat it.

Thanks

Yahoo, There should be vacuum at oil mist eliminator inlet then only it will pull vapour from oil system. We noticed once that mist fan impeller was detached and only motor was running and hence no vacuum was produced. What is lube oil top up rate ?

Dear Raj,

Mine is an old machine 1979 make and does not have any oil mist eliminator system installed.
Its mist is vented into atmosphere and any condensed is sent to drain. In one year approx. 24 drum (208lit) is consumed.

Please advice accordingly.

Yahoo, Since last 15 years or more Frame 5 GT is invariably fitted with oil mist eliminator which recovers oil from the reservoir and bearing vent pipes. This solution can be applied as a modification.
For increased leakage for your machine : I guess there may be increased bearing seal clearances causing more air entry in to the syatem. Also check breathers condition.

Thanks Raj.

But as I mentioned that this old model is without this modification. Also it is very costly around 50,000USD.

As far as bearing seal clearances are concerned, I installed new seals but to no avail. But could u please suggest the probable cause of the increased pressure. As this sealing air comes from the 10th stage extraction, do you think it is the increased compressor pressure causing this high pressure in console. But then there are orifices in the lines prior to the bearings.

YaHOO,WHO SUPPLIED THE SEALS? IF YOU WANT REAL TIME HELP SEND ME AN EMAIL; INFO@GPGSCO.COM...

So EJ, what do you think that caused the excessive oil mist?

GPGSCO the seals are OEM supplied.

This thread is going no where... Josh, I'm no oil mist expert but there are many simple reasons for such. I've experienced partial clogged drain passages within the bearing housing and gummed up drains in the actual seals. Rotten piping can do it and leaky gaskets anywhere in the air/oil system can make a difference. In my experience if the all systems are tight and clean of foreign/domestic debris everything works well.
Josh how is Borneo these days? Any other advice other than calling the OEM would be helpful...

Dear GPGS and Josh what is your experience regarding erosion of sealing air line orifices?

I am suspecting them to be a cause of this.
Any comments are very welcome.

Regards
Sabaq

Sabaq,

How long have they been installed? Other than deliberating the mass flow and velocity increase at the orphice and its inheritant erosion properties; Changing the orphices is inexpensive and will allow a thorough inspection of all the flanges and replacement of their gaskets.

If you can't remember when you last chaged them then now is a good time. Exchange about them every 5 years and you won't have any problem with them.

When changing your oil deflectors/seals be certain to mechanically clear all the oil drain holes in the housing as well as the seals. We use tig wire for this when the seals are out.

If you are using any RTV type sealant or similar near or between seals and bearing house upper/lower-halfs be carefull. Actually STOP. Prepare your surfaces correctly and you won't need it. If you believe you need it then add it sparingly, use as very little as possible.

quote:

How long have they been installed?

More than two decades , I think.
But blocking of drain holes immediately after a major inspection is not possible.

Hello, all:
I tell you my experience at SAICA-3 Frame 6 GT. We suspect a high oil demister flow during 2007, we now think it was caused by one opening to the oil tank not correctly closed. We also wonder if this can be the cause of dark colour in the oil which was changed just one year ago. Is your turbine oil colour dark?
Abour new oil demisters for oldest turbines, we are thinking to put one at SAICA-1 F6 turbine. We are alse looking non G.E. supplyers (probably cheaper)
Oil temperature: 48..51 ºC in the four SAICA Frame 6 machines.
30 mm H2O seems enormous pressure for console.I suposse oil vent will be big diameter (3" or 4")and direct pipe to atmosphere. Can you apreciate air flow at its outlet? Do you know the normal pressure in others Frame 5?
Orifice erosion seems rare with air flow, but after almost 30 years, is justified the checking of these orifices.
Compressor presure, I guess, will decrease with years, not increase.
Hope some of this can be useful.

Hey Josh. I work for one of the OEM's. Are you using a venturi or vortex style system? If you are using a true Oil Mist System, the system by design wont start producing more mist on its own. Something external probably cause it. If the mist manifold pressure and the air inlet pressure have not changed, then the system should be producing the same amount of mist. If you have multiple points of application and some are plugged, your mist pressure will increase, thus increasing the amount going to the other points. If you can get me some specs on how you are using it, i.e. number of points, air pressure, mist pressure etc.. I might be able to help. Hope it isnt too late. thanks