GE Frame 5 gas turbine BB#2 12.69 mm/sec high vibration on 50% 7MW load while BB1 8.59 mm/sec & BB2 2.55mm/sec are running normal.
what could be happen?

 

First, please check the information you provided. It's unclear and confusing. Usually GT Bearing #1 has two sensors, usually identified as BB1 and BB2. GT Bearing #2 has two sensors, usually identified as BB4 and BB5 (BB3 is usually skipped for two bearing machines like Frame 5s). You mention BB#2 and then BB1 and BB2.

Second, has anyone gone out to the unit and felt any excessive vibration around either the #1 bearing area or the #2 bearing area?

Third, does the unit have redundant sensors on both the #1 and #2 bearings? If so, what are they reading? If it's only a single sensor of a redundant pair and no human has felt excessive vibration at either end of the turbine shaft then the problem is most likely something is amiss with the sensor with the "excessive" reading (temperature problems; loose sensor bolt(s); loose connector; loose wire termination along the circuit between the sensor and the turbine control system; a problem with that partiular sensor input channel (though if it was a GE Mark* turbine control system it would likely have a Diagnostic Alarm to indicate a problem with the input channel).

Which brings us to fourth, what turbine control system is being used on the turbine?

Fifth, does the turbine have Bently-Nevada proximity sensors on the turbine bearings? If so, what are they indicating (both ends of the turbine)?

 

@WTF? I have also noticed that original post was unclear, that is the reason why I did not want to reply yet...

 

WTF?
ControlsGuy25
Sorry for insufficient provided data, This is GE Frame5 gas turbine running 16MW generator and its have 3 bearings BB#1, BB#2 & BB#3 each bearing installed one seismic vertical probe. now its running on 7MW load and BB#2 vibration is alarming upto 12.69 mm/sec while BB#1 8.59 mm/sec & BB#3 2.55mm/sec are running normal.
BB#1 Axial compressor suction side
BB#2 Axial compressor exhaust side
BB#3 Turbine exhaust side
Turbine control system is GE MARK5 & there is no BNC panel.

 

WTF?
ControlsGuy25
Sorry for insufficient provided data, This is GE Frame5 gas turbine running 16MW generator and its have 3 bearings BB#1, BB#2 & BB#3 each bearing installed one seismic vertical probe. now its running on 7MW load and BB#2 vibration is alarming upto 12.69 mm/sec while BB#1 8.59 mm/sec & BB#3 2.55mm/sec are running normal.
BB#1 Axial compressor suction side
BB#2 Axial compressor exhaust side
BB#3 Turbine exhaust side
Turbine control system is GE MARK5 & there is no BNC panel.

@TANWEER

Thank you for clarifying the issue..

Also please try to answer to @WTF? questions:

Second, has anyone gone out to the unit and felt any excessive vibration around either the #1 bearing area or the #2 bearing area?

Third, does the unit have redundant sensors on both the #1 and #2 bearings? If so, what are they reading? If it's only a single sensor of a redundant pair and no human has felt excessive vibration at either end of the turbine shaft then the problem is most likely something is amiss with the sensor with the "excessive" reading (temperature problems; loose sensor bolt(s); loose connector; loose wire termination along the circuit between the sensor and the turbine control system; a problem with that partiular sensor input channel (though if it was a GE Mark* turbine control system it would likely have a Diagnostic Alarm to indicate a problem with the input channel).

After that we will be able to add notes and try to help you as best as we can from here.

 

Thank you dear,
yes we acquire the vibration data with CSI-2140 on BB#2 its max vibration up to 10mm/sec

 

Thanks for clarifying. This must be a pretty old machine to have three bearings (I presume you are referring to a bearing between the axial compressor and the turbine section--please clarify if otherwise). I AM NOT singling you our, TANWEER, but this is a HUGE problem with people who think that EVERY GE-design Frame "n" is like EVERY OTHER GE-design Frame "n" heavy duty gas turbine. And the Frame 5 has been produced for more than 70 years (that's 7 decades--more than half a century). There have even been many two-shaft GE-design heavy duty gas turbines, some used for power generation but most were used for mechanical drive applications (centrifugal compressors; pumps; etc.).

So you've used some other vibration measurement sensor/equipment and it also says there is high vibration on the #2 bearing. (I presume that also means the people taking the measurements felt the vibration, also....)

If this is a single shaft machine (axial compressor and turbine section combined in a single shaft) it's likely that there is some mechanical problem with the coupling between the axial compressor and the turbine section (if they are bolted together--which was a common method of combining the two sections) OR a problem with bearing (worn; oil flow problem (could be too little or too much) OR a L.O. temperature problem or possibly a cooling and sealing air problem around the #2 bearing housing. I have only seen photos of a similar machine, and I don't exactly recall how the #2 bearing is lubricated and how the oil drain is connected to the bearing housing.

But, if you have "verified" the problem with a second vibration sensor, then it's most likely NOT a turbine control system problem but some kind of mechanical problem. AND, if there were some kind of Mark* V turbine control system problem there would most likely be some kind of Diagnostic Alarm to indicate such a problem.

What Diagnostic Alarms are present on the Mark* V when this excessive vibration is occurring?

I wish I could have been more help.

Let us know what you find, please.

 

WTF?
Thank you for your quality time
when we increase the load up to 10MW the BB#2 vibration goes down from 12mm/sec to 8mm/sec now machine is running on normal parameters, & this turbine commissioned in 1965 its very smooth GE Turbine.

 

Two things.

First, this forum is about automation and controls. The Mark* V will generate a Diagnostic Alarm if a vibration input channel is not working correctly. You haven’t told us what alarms (Process and Diagnostic) are present when you are experiencing this problem. But, as was written, it’s most very likely the problem is real and mechanical—NOT controls-related.

Second, WHEN DID THIS PROBLEM START? After a maintenance outage? After a trip from load? Did the problem suddenly appear, or did it gradually appear? What is the L.O, temperature now, and what was it when the the vibration wasn’t a problem? Has the ambient temperature changed since the problem started? When was the last time the machine was shut down for a maintenance outage? What mechanical work was done during the last maintenance outage? Has the machine rotor ever been replaced?

But, still—and most importantly—it’s not likely the problem is controls-related. And, sometimes you gotta crack a few bolts if you want to fix a problem you can’t identify easily.

Best of luck.

 

Thanks for clarifying. This must be a pretty old machine to have three bearings (I presume you are referring to a bearing between the axial compressor and the turbine section--please clarify if otherwise). I AM NOT singling you our, TANWEER, but this is a HUGE problem with people who think that EVERY GE-design Frame "n" is like EVERY OTHER GE-design Frame "n" heavy duty gas turbine. And the Frame 5 has been produced for more than 70 years (that's 7 decades--more than half a century). There have even been many two-shaft GE-design heavy duty gas turbines, some used for power generation but most were used for mechanical drive applications (centrifugal compressors; pumps; etc.).

So you've used some other vibration measurement sensor/equipment and it also says there is high vibration on the #2 bearing. (I presume that also means the people taking the measurements felt the vibration, also....)

If this is a single shaft machine (axial compressor and turbine section combined in a single shaft) it's likely that there is some mechanical problem with the coupling between the axial compressor and the turbine section (if they are bolted together--which was a common method of combining the two sections) OR a problem with bearing (worn; oil flow problem (could be too little or too much) OR a L.O. temperature problem or possibly a cooling and sealing air problem around the #2 bearing housing. I have only seen photos of a similar machine, and I don't exactly recall how the #2 bearing is lubricated and how the oil drain is connected to the bearing housing.

But, if you have "verified" the problem with a second vibration sensor, then it's most likely NOT a turbine control system problem but some kind of mechanical problem. AND, if there were some kind of Mark* V turbine control system problem there would most likely be some kind of Diagnostic Alarm to indicate such a problem.

What Diagnostic Alarms are present on the Mark* V when this excessive vibration is occurring?

I wish I could have been more help.

Let us know what you find, please.

@WTF? , @ControlsGuy25. Thanks for your reply, we are similar issues with our GE frame 9E gas turbine. the machine is running to 65% speed and 1800RPM, it will trip on high vibration with BB1 and BB2 are the flashing yellow, later flash red and the unit will trip. we have done alignment on the shaft. Please, i am seriously looking for help. We have change the seismic vibration sensor. Your advice is highly appreciated.

 

@EBUWAODUWA,

Your post really belongs in its own thread. Frame 5's and Frame 9E's are similar machines, but in many respects they are very different--Frame 9E's having been developed much later than Frame 5's with different technologies and auxiliaries even though the basic suck, squeeze, burn, blow fundamentals (draw air into the axial compressor; compress that air; add some fuel to the air and burn the fuel, and exhaust the hot combustion gases after passing through the turbine section).

Has anyone been beside the Frame 9E during starting to experience the high vibrations--in other words, is the vibration real and seem excessive?

Shaft alignment is one thing that can affect vibration. Axial compressor condition and #2 bearing condition can also affect vibration. You say you aligned the shaft. The machine shaft consists of an Accessory Coupling, the axial compressor shaft, the turbine section shaft, and a Load Shaft. What exactly was aligned? And was any alignment done shortly before the high #2 Bearing vibration started?

Bearing condition (clearances) can be a large factor in vibration analysis.

What is the bearing header Lube Oil temperature when you are STARTing the machine? If it's less than about 60 deg F the vibration will be accentuated.

WHEN DID THIS PROBLEM START? After a trip from load? After a maintenance outage? After a Lube Oil issue (high temperature or low temperature Lube Oil? Low Lube Oil pressure? Problems with cooling of the #2 Bearing assembly (the "turbine inner barrel")? Problems with the Lube Oil Mist Eliminator (which draws vapors and hot air from the #2 Bearing area)? Has the vibration increased over time (days, weeks, months)--or did it just begin with seemingly no stimulus?

You say you have replaced the seismic (velocity) vibration sensors. Are you ABSOLUTELY certain the scaling of both the OLD and the NEW transducer are exactly the same?

Did you change BOTH the seismic vibration sensors on the #1 Bearing? The #2 Bearing usually only has one, single vibration sensor and it's mounted on the #2 Bearing Lube Oil pipe. So, did you change one, two or three vibration sensors?

What is the turbine control system of the machine? If it's a digital Mark* turbine control system, what are the Diagnostic Alarms present during STARTing and annunciated at the time of the high vibration? Are any of the Diagnostic Alarms related to the vibration issues? (Diagnostic Alarms are supposed to alert the operator to problems with the turbine control system--printed circuit cards, unexplained voting mismatches, power supply issues, etc.) Digital control systems settings don't "drift" (change) over time, so it's not likely that in the absence of related Diagnostic Alarms there's a problem with the turbine control system. You mention yellow and red flashing "lights"--is this happening on the turbine control system HMI display?

Does the machine have a Bently-Nevada proximity-measuring monitor connected to proximitors on the bearings and a keyphasor measuring shaft speed? Is the B-N vibration monitor indicating the same or nearly the same vibration problems?

The problem can be a lot of issues--and as you can see, we don't have much information to work with which is why we ask all of the questions above. If you're convinced there are no wiring issues with the vibration sensors on the #1- and #2 Bearings, the scaling of the outputs of the vibration sensors match the scaling of the input channels of the turbine control system, and are reasonable certain there are no ovbiously related issues with the vibration sensing portion (printed circuit cards, terminal boards, etc.) and that the shield grounds of the interconnecting cabling/wiring between the vibration inputs and the vibration sensors is 100% okay, AND when someone is standing on the grating next to the turbine compartment when the machine is STARTing and can feel the high vibrations then it's likely NOT a controls-related issue--it's something wrong with the mechanical bits of the axial compressor shaft and/or bearings.

Again, it's not a "feature" of digital control system settings to drift over time; older control systems with lots of potentiometers were prone to drifting, but not so digital control systems. If the control system isn't warning of any vibration monitoring issues with the physical components of the control system, then it could be the wiring connecting the sensors to the control system. If the wrong sensors or the wrong scaling for the sensor outputs (mV per inch) then that is a problem--and while may seismic vibration sensors look alike they can have very different scaling. And the scaling of the control system input(s) must match the scaling of the sensor(s).

The mechanical department and plant management don't like to hear that it's most likely NOT the turbine control system. So, be sure it's not the control system or the wiring or the sensors (or how the sensors are mounted!) and then they can't continue to say, "It's that #$*&ing turbine control system!" Sure, it's costly to have to disassemble the machine to investigate or resolve issues--but that's how this works. Prove--to the best or your ability--that it's highly likely the turbine control system IS NOT to blame (or the wiring or the sensors or the way the sensors were mounted) and then start making a list of the most likely issues and then which ones are the easiest to investigate and start there. Logical troubleshooting is best. If you need to get someone to site with experience with the turbine control system, do so.

But, if someone (you?) has actually experienced excessive vibrations while standing on the grating immediately outside the turbine compartment when the machine is being STARTed and you can eliminate the turbine control system with a high degree of certainty then it's most likely the control system is correct and the problem is mechanical in nature.

You've been given lots of possibilities--some of which you may have already investigated and/or eliminated (but didn't tell us) and you can use them to troubleshoot the problem. Apologies if some of them you have tried already--but we don't know that (unless you tell us).

And, in the future while you may find a similar thread, please open a new thread which is appropriate to the machine you are working on and the problem(s) you are experiencing.

Please write back to let us know what you find. Some of the threads on Control.com have tens of thousands of views--meaning they are read for years after they are begun. That's one of the best things about Control.com--the feedback from people who post for information and/or assistance. The feedback lets others know who read the threads--now and in the future--what worked or what didn't.

 

@EBUWAODUWA,

Here's one way to open a new thread. From the top of this thread you will see this:



Click on Forums and then you will see this:



Click on Post New Thread and start your own thread specific to your machine and your issue(s). DO NOT worry about which forum to post in--a LOT of threads are posted in odd forums, and the posts are not deleted or moved. I do suggest posting to Power Generation if your problem relates to a GE-design heavy duty gas turbine control system/machine.

Have fun!

Please post as much information as you can about the problem, when it started, what you've done (how you've done what you've done) and what the results were (something more than the problem still persists). You will most likely be pleasantly surprised at the quality--and brevity--of the replies!

 

@EBUWAODUWA,

Your post really belongs in its own thread. Frame 5's and Frame 9E's are similar machines, but in many respects they are very different--Frame 9E's having been developed much later than Frame 5's with different technologies and auxiliaries even though the basic suck, squeeze, burn, blow fundamentals (draw air into the axial compressor; compress that air; add some fuel to the air and burn the fuel, and exhaust the hot combustion gases after passing through the turbine section).

Has anyone been beside the Frame 9E during starting to experience the high vibrations--in other words, is the vibration real and seem excessive?

Shaft alignment is one thing that can affect vibration. Axial compressor condition and #2 bearing condition can also affect vibration. You say you aligned the shaft. The machine shaft consists of an Accessory Coupling, the axial compressor shaft, the turbine section shaft, and a Load Shaft. What exactly was aligned? And was any alignment done shortly before the high #2 Bearing vibration started?

Bearing condition (clearances) can be a large factor in vibration analysis.

What is the bearing header Lube Oil temperature when you are STARTing the machine? If it's less than about 60 deg F the vibration will be accentuated.

WHEN DID THIS PROBLEM START? After a trip from load? After a maintenance outage? After a Lube Oil issue (high temperature or low temperature Lube Oil? Low Lube Oil pressure? Problems with cooling of the #2 Bearing assembly (the "turbine inner barrel")? Problems with the Lube Oil Mist Eliminator (which draws vapors and hot air from the #2 Bearing area)? Has the vibration increased over time (days, weeks, months)--or did it just begin with seemingly no stimulus?

You say you have replaced the seismic (velocity) vibration sensors. Are you ABSOLUTELY certain the scaling of both the OLD and the NEW transducer are exactly the same?

Did you change BOTH the seismic vibration sensors on the #1 Bearing? The #2 Bearing usually only has one, single vibration sensor and it's mounted on the #2 Bearing Lube Oil pipe. So, did you change one, two or three vibration sensors?

What is the turbine control system of the machine? If it's a digital Mark* turbine control system, what are the Diagnostic Alarms present during STARTing and annunciated at the time of the high vibration? Are any of the Diagnostic Alarms related to the vibration issues? (Diagnostic Alarms are supposed to alert the operator to problems with the turbine control system--printed circuit cards, unexplained voting mismatches, power supply issues, etc.) Digital control systems settings don't "drift" (change) over time, so it's not likely that in the absence of related Diagnostic Alarms there's a problem with the turbine control system. You mention yellow and red flashing "lights"--is this happening on the turbine control system HMI display?

Does the machine have a Bently-Nevada proximity-measuring monitor connected to proximitors on the bearings and a keyphasor measuring shaft speed? Is the B-N vibration monitor indicating the same or nearly the same vibration problems?

The problem can be a lot of issues--and as you can see, we don't have much information to work with which is why we ask all of the questions above. If you're convinced there are no wiring issues with the vibration sensors on the #1- and #2 Bearings, the scaling of the outputs of the vibration sensors match the scaling of the input channels of the turbine control system, and are reasonable certain there are no ovbiously related issues with the vibration sensing portion (printed circuit cards, terminal boards, etc.) and that the shield grounds of the interconnecting cabling/wiring between the vibration inputs and the vibration sensors is 100% okay, AND when someone is standing on the grating next to the turbine compartment when the machine is STARTing and can feel the high vibrations then it's likely NOT a controls-related issue--it's something wrong with the mechanical bits of the axial compressor shaft and/or bearings.

Again, it's not a "feature" of digital control system settings to drift over time; older control systems with lots of potentiometers were prone to drifting, but not so digital control systems. If the control system isn't warning of any vibration monitoring issues with the physical components of the control system, then it could be the wiring connecting the sensors to the control system. If the wrong sensors or the wrong scaling for the sensor outputs (mV per inch) then that is a problem--and while may seismic vibration sensors look alike they can have very different scaling. And the scaling of the control system input(s) must match the scaling of the sensor(s).

The mechanical department and plant management don't like to hear that it's most likely NOT the turbine control system. So, be sure it's not the control system or the wiring or the sensors (or how the sensors are mounted!) and then they can't continue to say, "It's that #$*&ing turbine control system!" Sure, it's costly to have to disassemble the machine to investigate or resolve issues--but that's how this works. Prove--to the best or your ability--that it's highly likely the turbine control system IS NOT to blame (or the wiring or the sensors or the way the sensors were mounted) and then start making a list of the most likely issues and then which ones are the easiest to investigate and start there. Logical troubleshooting is best. If you need to get someone to site with experience with the turbine control system, do so.

But, if someone (you?) has actually experienced excessive vibrations while standing on the grating immediately outside the turbine compartment when the machine is being STARTed and you can eliminate the turbine control system with a high degree of certainty then it's most likely the control system is correct and the problem is mechanical in nature.

You've been given lots of possibilities--some of which you may have already investigated and/or eliminated (but didn't tell us) and you can use them to troubleshoot the problem. Apologies if some of them you have tried already--but we don't know that (unless you tell us).

And, in the future while you may find a similar thread, please open a new thread which is appropriate to the machine you are working on and the problem(s) you are experiencing.

Please write back to let us know what you find. Some of the threads on Control.com have tens of thousands of views--meaning they are read for years after they are begun. That's one of the best things about Control.com--the feedback from people who post for information and/or assistance. The feedback lets others know who read the threads--now and in the future--what worked or what didn't.

Yes we have a Bentley Navada, We only change the seismic vibration sensor on BB1 and BB2. The accessory coupling was align, alignment was done before the vibration issue started, The vibration is on #1 bearing. BB1 and BB2 is the device that tripped the machine. there is no vibration when you stand at the grating, there is no vibration when you put your hand at the bearing casing in #1 bearing.