V
Any body can advice for oil leakage through oil guard of Axillary gear box High speed shaft GE Frame 5. The oil guard was removed and assembled with Gasket sealant many times with equal gaps. But still the same..
I have never seen an Auxiliary gear box.
Accessory Gear Box. Load Gear Box. Reduction Gear Box.
But never an Auxiliary Gear Box.
And, when did this problem start? After some maintenance outage?
What is the Lube Oil supply pressure to the gear box?
Does this problem occur when the shaft is not turning (when the unit is on Cooldown)?
Does this problem only occur when the Main L.O. pump is running (when the shaft is above, say, approximately 50 RPM)? Is the Main L.O. Pump discharge pressure "regulator" set correctly?
Was the bearing changed before this problem started?
What is the internal pressure inside the "Axillary" gear box?
Some Accessory Gear Boxes have "eductor" vents which were used to reduce the internal pressure inside the gear box to prevent oil from being "blown" out the seals? Have you looked at the L.O. System Piping Schematic (P&ID) drawing to see if your "Axillary" gear box is supposed to have any kind of vent or eductor and then have you checked your gear box to see that it's working correctly?
I've seen some Cooling & Sealing Air piping reassembled without orifices installed that have caused this kind of problem, or reassembled with the wrong orifices installed.
But, this isn't a controls-related problem.
Accessory Gear Box. Load Gear Box. Reduction Gear Box.
But never an Auxiliary Gear Box.
And, when did this problem start? After some maintenance outage?
What is the Lube Oil supply pressure to the gear box?
Does this problem occur when the shaft is not turning (when the unit is on Cooldown)?
Does this problem only occur when the Main L.O. pump is running (when the shaft is above, say, approximately 50 RPM)? Is the Main L.O. Pump discharge pressure "regulator" set correctly?
Was the bearing changed before this problem started?
What is the internal pressure inside the "Axillary" gear box?
Some Accessory Gear Boxes have "eductor" vents which were used to reduce the internal pressure inside the gear box to prevent oil from being "blown" out the seals? Have you looked at the L.O. System Piping Schematic (P&ID) drawing to see if your "Axillary" gear box is supposed to have any kind of vent or eductor and then have you checked your gear box to see that it's working correctly?
I've seen some Cooling & Sealing Air piping reassembled without orifices installed that have caused this kind of problem, or reassembled with the wrong orifices installed.
But, this isn't a controls-related problem.
V
vasanth
Dear CSA,
Thanks for your response. Auxillary gear box i.e Between Diesel Engine and Gas Turbine in built with Main oil pump. The Lube oil header pressure was 25kg/cm2. The oil leak does not occur at the time of cool down and also in FSNL. The leak occurs while gradually increasing the Load. Recently we have lubricated the fluxable coupling with grease.
Thanks for your response. Auxillary gear box i.e Between Diesel Engine and Gas Turbine in built with Main oil pump. The Lube oil header pressure was 25kg/cm2. The oil leak does not occur at the time of cool down and also in FSNL. The leak occurs while gradually increasing the Load. Recently we have lubricated the fluxable coupling with grease.
That's the Accessory Gear Box.
If the oil leak starts as the machine is loaded, then it's definitely caused by something amiss with the Cooling and Sealing Air System, or with excessive pressure in the Accessory Gear Box.
You <b>DID NOT</b> indicate you had reviewed the L.O. System Piping Schematic (P&ID) to see if there is any kind of vent or eductor on the Accessory Gear Box. Also, check the Notes on the drawing to see if there is any information about the vent of the Accessory Gear Box. Only you can review the drawing for your turbine; we can't, so you're going to have to find and use the information on that drawing to resolve your problem.
25 kg/cm2 is HUGELY high. Typical L.O. Bearing Header pressure is 25 psig (approx. 1.7 barg). The Main L.O. Pump (usually a positive displacement pump) discharge pressure is usually set by adjusting a relief valve (yes; a relief valve) to the value specified in the Device Summary for the Main L.O. Pump Relief Valve (VR1-1, I believe).
You also didn't indicate if you'd checked the pressure in the Accessory Gear Box. This can easily be done with a water-tube manometer (use your preferred Internet search engine to see just how easy this is). You should also be checking the pressure on the L.O. Tank; it's probably higher than it should be also. The desired pressure is usually listed in a Note on the L.O. System Piping Schematic Drawing (P&ID).
The Piping Schematic Drawings (P&IDs), love them or hate them, are key to understanding how the various systems of the turbine work and work together. Ignore them at your own peril. Embrace them and you will find many answers to questions and solutions to problems.
I'm going to ignore the comment about the flexible coupling, because you have said the oil leak is coming from the Accessory Gear Box, not from the Accessory Coupling.
If the oil leak starts as the machine is loaded, then it's definitely caused by something amiss with the Cooling and Sealing Air System, or with excessive pressure in the Accessory Gear Box.
You <b>DID NOT</b> indicate you had reviewed the L.O. System Piping Schematic (P&ID) to see if there is any kind of vent or eductor on the Accessory Gear Box. Also, check the Notes on the drawing to see if there is any information about the vent of the Accessory Gear Box. Only you can review the drawing for your turbine; we can't, so you're going to have to find and use the information on that drawing to resolve your problem.
25 kg/cm2 is HUGELY high. Typical L.O. Bearing Header pressure is 25 psig (approx. 1.7 barg). The Main L.O. Pump (usually a positive displacement pump) discharge pressure is usually set by adjusting a relief valve (yes; a relief valve) to the value specified in the Device Summary for the Main L.O. Pump Relief Valve (VR1-1, I believe).
You also didn't indicate if you'd checked the pressure in the Accessory Gear Box. This can easily be done with a water-tube manometer (use your preferred Internet search engine to see just how easy this is). You should also be checking the pressure on the L.O. Tank; it's probably higher than it should be also. The desired pressure is usually listed in a Note on the L.O. System Piping Schematic Drawing (P&ID).
The Piping Schematic Drawings (P&IDs), love them or hate them, are key to understanding how the various systems of the turbine work and work together. Ignore them at your own peril. Embrace them and you will find many answers to questions and solutions to problems.
I'm going to ignore the comment about the flexible coupling, because you have said the oil leak is coming from the Accessory Gear Box, not from the Accessory Coupling.
> If the oil leak starts as the machine is loaded, then it's definitely caused by something amiss with the Cooling and Sealing Air System, or with excessive pressure in the Accessory Gear Box. <
The above comment should have been more specific. CPD increases as the unit is loaded. And that means the Cooling & Sealing Air System Pressure also increases as the unit is loaded (and CPD increases). Which means the pressure on the L.O. Tank also increases as the unit is loaded (and CPD increases).
> I'm going to ignore the comment about the flexible coupling, because you have said the oil leak is coming from the Accessory Gear Box, not from the Accessory Coupling. <
I suppose it's possible that too much fluid was added to the coupling and that has caused some increased vibration, but when the unit is producing power (at rated speed, presuming the frequency is stable) then speed shouldn't be changing so I wouldn't expect the vibration to increase. And, the load on the accessory coupling shouldn't be increasing by very much in any case so it doesn't seem like it's a vibration-related issue.
Nor does it seem like a controls-related issue.
The above comment should have been more specific. CPD increases as the unit is loaded. And that means the Cooling & Sealing Air System Pressure also increases as the unit is loaded (and CPD increases). Which means the pressure on the L.O. Tank also increases as the unit is loaded (and CPD increases).
> I'm going to ignore the comment about the flexible coupling, because you have said the oil leak is coming from the Accessory Gear Box, not from the Accessory Coupling. <
I suppose it's possible that too much fluid was added to the coupling and that has caused some increased vibration, but when the unit is producing power (at rated speed, presuming the frequency is stable) then speed shouldn't be changing so I wouldn't expect the vibration to increase. And, the load on the accessory coupling shouldn't be increasing by very much in any case so it doesn't seem like it's a vibration-related issue.
Nor does it seem like a controls-related issue.
