High Pressure on Lube Oil Tank

K

Thread Starter

khairi

dear friends,

we have problem with our turbine. it tripped to high pressure on lube oil tank, and this is our procedure which we have done.

1-we checked the butterfly valve and we to adjust with but it still the same

2-we found unintended bolts on the lube oil tank and it still the same problem.

friends this problem confused me. waiting for your feedback.
 
khairi,

Contrary to popular belief, the elements used in most L.O. Mist Eliminators require periodic replacement, and if not replaced they can become quite clogged.

Is there a gage installed to measure the L.O. tank pressure/vacuum? If so, what does it read when the unit is at FSNL? I also recommend installing a gage on the upstream side of the butterfly valve so as to be able to determine the differential across the Mist Eliminator elements. It, too, should be a combination vacuum/pressure gage.

There have been problems with the set-screws of the coupling between the motor and the fan coming loose. Also, there have been many issues with the three-phase motor leads being incorrectly terminated after an outage, causing the fan to rotate in the wrong direction.

If the L.O. Mist Eliminator is working properly and the butterfly valve position is not capable of reducing the pressure on the L.O. tank as the machine is loaded the most likely cause is missing or incorrect diameter orifice(s) in the bearing cooling/sealing air supply lines after a maintenance outage.

About the only other possibility is if there is a manual valve on a bearing sealing air separator out of position, or if the machine is a two-shaft machine and the L.O. is being used for seal oil and there is a large leak from the seals. But, you haven't told us what the turbine is driving.

Another thing which surprises most people about "GE" heavy duty gas turbines is that while they all compress air and burn fuel to produce torque, all Frame 5s are not alike. They can have very different accessory systems, be single- or two-shaft machines, burn very different fuels, and be packaged very differently (enclosures; starting means; etc.)--not to mention the different types of combustors, inlet air filters, and exhaust configurations. You see your unit every day--we don't. The more information you can provide about the unit at your site the better information you will likely get in return.

Also, unless the speed pick-up gap was on the very high side of 0.050 + 0.010 inches AND the liquid fuel flow divider is old and worn, reducing the gap was most likely <b>NOT</b> the reason for the disappearance of the excessive fuel flow alarm/trip. Air in the liquid fuel piping is what usually what causes excessive fuel flow alarms/trips. And, the control system didn't put the air in there.

Hope this helps!
 
Dear friends

the problem which we have now with turbine. we thought that problem from transmitter, but when we installed new transmitter still the same. that means it true reading. friends what i have to check? tell me the normal steps to solve high pressure on GE frame 5 turbines mark vie.

regards
waiting for feedback.
 
Hi Khairi,

Assuming that your gas turbine model is "C" and above. Your problem is malfunction of oil mist eliminator. Open the filter drum, replace the fine filter cartridges. Clean the drum internal and also ensure that the drain to the tank is free for flow. Some filter drums also have a mesh screen below. Ensure that it is also clean.

Make all gages and switches on the eliminator functional. Also look at the vacuum breaker valve and its filter. Change if it is blocked. Also look at the blower. When contamination is high inside the filter drum, it propagates to the blower and its diffuser and silencers. Make sure it is functioning as it is intended.

After you did all of the above, start the blower with fully open vacuum breaker valve and then slowly close until the desired vacuum level is achieved.

If above does not work, then suspect from the sealing air to the bearings. There may be some excessive air flowing to the bearings that oil mist eliminator could not pump out. (but unlikely)
 
DEAR friends,

if we suppose that problem from bearing. how could i know that its excessive air flowing to the bearings that oil mist eliminator could not pump out?

regards
 
DEAR Khairi,

It is possible, but, concentrate on the mist eliminator fan and its extraction system from the lube oil tank. In my life I have seen many demisters filter drums full of sludge after years of operation with no maintenance. I would recommend first thing first to ensure that demister fan is operating intact. As well as ensure that no air leaking to lube oil tank anywhere.

Bearing sealing air lines are equipped with orifices to restrict air flow to the bearings. You can check the size of these orifices are correct or not. If they are at the correct size with the sizes given in the P&IDs. Then no worry.
 
DEAR friends,

> if we suppose that problem from bearing. how could i know that its excessive air flowing
> to the bearings that oil mist eliminator could not pump out?

and what about the s pacification of lube oil because the lube oil cooler changed? it seems it black. i doubt the lube oil is not ok is it effect.
 
Sure sounds like the lube oil is "dead"--for whatever reason. Did someone leave the L.O. Tank Heater(s) energized and shut off the Aux. L.O. Pump?

And, if the L.O. is "carbonized" then it's a good bet the L.O. Mist Eliminator elements are clogged.

Best to have an analysis of the L.O. performed, and then looking at the results one can try to determine the root cause of the oil problem and work to resolve it.
 
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