High Vibration on Start up gas turbine

We are having an issue on Solar titan gas turbines during start up. The maximum speed is 11,197 rpm for the turbine. It is connected to alternator with planetary gear box. High vibration on bearing 1 which is at cold side. Alarm value set is 63.5 microns and we got highest vibration yesterday is 72 microns.
High vibration only occurs at 40 to 45% of turbine's rpm. Once it crosses that range the vibration goes down and got stable about 25 microns. There is no overhauling or other work is done in the past year. I am suspecting the oil whirl is the issue. But need suggestion from you guys. Thank you
 
Is this a controls issue? Is the thickness of the oil wedge monitored or controlled by the TurboTronics?

If you have actual excessive vibration, and it seems to coincide with the readings on the turbine control system, then it's not a sensor/control system issue.

And, most rotating machines have at least one critical speed--a speed at which the vibrations are highest during start-up and acceleration but because the unit doesn't operate continuously at this speed is not considered to be a problem. UNLESS, there is something which is making the vibration at the critical speed worse--such as something which has come loose, or something which as broken free, or something which has been bent out of shape. Or some deposits on rotors which are causing an imbalance which makes the vibration higher at a critical speed. But none of things are controlled by the TurboTronics.

You didn't mention what the oil temperature is during start-up, or if it has changed recently.

And why would you suspect oil whirl? Does the oil need replacing? Is it tested regularly?
 
Hi CSA ,
Thanks for your reply.

Critical speed of the machine is 4300 rpm or 38.3% NGP defined by OEM.
Oil Temp during start up 53.762 C
i suspected Oil whirl due to its frequency as it should be between 0.38 to 0.48 of running speed.
Oil testing is done every three months. Last was done in the March 2020 by me.
I am sending here some orbit plots and spectrum before the event and during event, which are taken from ADRE Sxp instrument.
Your help will be appreciated and helpful.
High vibration alarm event occur at 15:47:43 on 1st July 2020.
Thank you
 

Attachments

Whoa. I am many things--but a vibration analyst is NOT one of them.

I was really trying to point out this is a controls-related forum. Vibration analysis; oil analysis; these are things which are not varied, regulated or controlled by the turbine control & protection system.

I have seen oil whip caused by high temperature oil. I have little experience with or knowledge of Solar gas turbines, so I don't know if 57 deg C is normal, high or low for this particular model of machine.

We do get into mechanical issues and devices and instruments from time to time--those that are important to the proper operation and control and protection of the turbine, its driven device and auxiliaries. But this--this is pretty far out of the normal discussions and analysis we do here.

I strongly recommend you employ the services of a qualified person who can guide you in the review and analysis of this issue. Sometimes you just gotta call and engage the right people--like someone with the OEM (Original Equipment Manufacturer).

Best of luck. Be safe, and stay healthy!!!
 
Hi CSA ,
Thanks for your reply.

Critical speed of the machine is 4300 rpm or 38.3% NGP defined by OEM.
Oil Temp during start up 53.762 C
i suspected Oil whirl due to its frequency as it should be between 0.38 to 0.48 of running speed.
Oil testing is done every three months. Last was done in the March 2020 by me.
I am sending here some orbit plots and spectrum before the event and during event, which are taken from ADRE Sxp instrument.
Your help will be appreciated and helpful.
High vibration alarm event occur at 15:47:43 on 1st July 2020.
Thank you
Hello ALL,
harsh1104

In my own experience in the field i learnt about vibration analysis on GE ALSTOM SIEMENS HDGT .

I advise you to perform phase analysis ( bode plot ) , polar graphic/plots shaft centerline plot that will give you, the needed datas for a better troubleshooting on vibration cause studies .


For example Bode plot :
Bode plot which is a double graph , will indicates the amplitude and the phase angle in dependency of the unit speed.

Also you gonna have to calculate Kurtosis value/RMS ....

As there a lot to say about vibration analysis i suggest you to read the herebelow book:
https://books.google.fr/books?id=TSfXDwAAQBAJ&pg=PA40&lpg=PA40&dq=ADRE+Sxp+instrument.&source=bl&ots=MKqwVO5RAV&sig=ACfU3U1s_z9kaGtIW6ObsrIjQGjoVJggsQ&hl=fr&sa=X&ved=2ahUKEwiE5vXl-L3qAhUHWBoKHVsmArsQ6AEwEnoECAoQAQ#v=onepage&q=ADRE Sxp instrument.&f=false

It will give you many needed informations that you are looking for studying these vibrations phenomena that you observing on this unit.

For sure such plots and studies , should be done as CSA mentionned by a "trained/certified Vibration analysis" engineer

You can check how these guys perform on ADRE Sxp instrument .

I am pretty sure that you can try to do some Bode ,Polar & shaft centerline /plots.

You may right when you saying that oil whirl can be cause of such vibration.
There is also " OIL WHIP " Phenomena to consider , you can have a search on its definition on Internet:

Oil whip vibration
2.1 Oil whip. Oil whip is a self-excited vibration caused by the oil film in sleeve bearings, and occurs if the signs of the cross-coupling stiffnesses of the oil film kxy and kyx are opposite, where the suffixes x and y denote the horizontal and vertical direction, respectively [5].

Here some notes to read about these 2 differents phenomena:
https://www.machinerylubrication.com/Read/754/oil-whirl-whip
https://www.turbomachinerymag.com/differentiating-between-fluid-induced-instability-oil-whirl-and-oil-whip-and-a-rub/
https://www.researchgate.net/publication/292996114_Faults_detection_in_gas_turbine_rotor_using_vibration_analysis_under_varying_conditions

It looks like these 2 excellents articles are describing what seems to occur at your site/unit.

Please have a carreful read on it.

A spectrum may definitely point the location and amplitude of the Bearing n°1 vibrations on this unit.
Here is an excellent artcile from Control.com :
https://control.com/textbook/machine-vibration-measurement/vibration-physics/



I am sure that this will help you !
ControlsGuy25.
 
Hello ALL,
harsh1104

In my own experience in the field i learnt about vibration analysis on GE ALSTOM SIEMENS HDGT .

I advise you to perform phase analysis ( bode plot ) , polar graphic/plots shaft centerline plot that will give you, the needed datas for a better troubleshooting on vibration cause studies .


For example Bode plot :
Bode plot which is a double graph , will indicates the amplitude and the phase angle in dependency of the unit speed.

Also you gonna have to calculate Kurtosis value/RMS ....

As there a lot to say about vibration analysis i suggest you to read the herebelow book:
https://books.google.fr/books?id=TSfXDwAAQBAJ&pg=PA40&lpg=PA40&dq=ADRE+Sxp+instrument.&source=bl&ots=MKqwVO5RAV&sig=ACfU3U1s_z9kaGtIW6ObsrIjQGjoVJggsQ&hl=fr&sa=X&ved=2ahUKEwiE5vXl-L3qAhUHWBoKHVsmArsQ6AEwEnoECAoQAQ#v=onepage&q=ADRE Sxp instrument.&f=false

It will give you many needed informations that you are looking for studying these vibrations phenomena that you observing on this unit.

For sure such plots and studies , should be done as CSA mentionned by a "trained/certified Vibration analysis" engineer

You can check how these guys perform on ADRE Sxp instrument .

I am pretty sure that you can try to do some Bode ,Polar & shaft centerline /plots.

You may right when you saying that oil whirl can be cause of such vibration.
There is also " OIL WHIP " Phenomena to consider , you can have a search on its definition on Internet:

Oil whip vibration
2.1 Oil whip. Oil whip is a self-excited vibration caused by the oil film in sleeve bearings, and occurs if the signs of the cross-coupling stiffnesses of the oil film kxy and kyx are opposite, where the suffixes x and y denote the horizontal and vertical direction, respectively [5].

Here some notes to read about these 2 differents phenomena:
https://www.machinerylubrication.com/Read/754/oil-whirl-whip
https://www.turbomachinerymag.com/differentiating-between-fluid-induced-instability-oil-whirl-and-oil-whip-and-a-rub/
https://www.researchgate.net/publication/292996114_Faults_detection_in_gas_turbine_rotor_using_vibration_analysis_under_varying_conditions

It looks like these 2 excellents articles are describing what seems to occur at your site/unit.

Please have a carreful read on it.

A spectrum may definitely point the location and amplitude of the Bearing n°1 vibrations on this unit.
Here is an excellent artcile from Control.com :
https://control.com/textbook/machine-vibration-measurement/vibration-physics/



I am sure that this will help you !
ControlsGuy25.
Hello ALL,
harsh1104

In my own experience in the field i learnt about vibration analysis on GE ALSTOM SIEMENS HDGT .

I advise you to perform phase analysis ( bode plot ) , polar graphic/plots shaft centerline plot that will give you, the needed datas for a better troubleshooting on vibration cause studies .


For example Bode plot :
Bode plot which is a double graph , will indicates the amplitude and the phase angle in dependency of the unit speed.

Also you gonna have to calculate Kurtosis value/RMS ....

As there a lot to say about vibration analysis i suggest you to read the herebelow book:
https://books.google.fr/books?id=TSfXDwAAQBAJ&pg=PA40&lpg=PA40&dq=ADRE+Sxp+instrument.&source=bl&ots=MKqwVO5RAV&sig=ACfU3U1s_z9kaGtIW6ObsrIjQGjoVJggsQ&hl=fr&sa=X&ved=2ahUKEwiE5vXl-L3qAhUHWBoKHVsmArsQ6AEwEnoECAoQAQ#v=onepage&q=ADRE Sxp instrument.&f=false

It will give you many needed informations that you are looking for studying these vibrations phenomena that you observing on this unit.

For sure such plots and studies , should be done as CSA mentionned by a "trained/certified Vibration analysis" engineer

You can check how these guys perform on ADRE Sxp instrument .

I am pretty sure that you can try to do some Bode ,Polar & shaft centerline /plots.

You may right when you saying that oil whirl can be cause of such vibration.
There is also " OIL WHIP " Phenomena to consider , you can have a search on its definition on Internet:

Oil whip vibration
2.1 Oil whip. Oil whip is a self-excited vibration caused by the oil film in sleeve bearings, and occurs if the signs of the cross-coupling stiffnesses of the oil film kxy and kyx are opposite, where the suffixes x and y denote the horizontal and vertical direction, respectively [5].

Here some notes to read about these 2 differents phenomena:
https://www.machinerylubrication.com/Read/754/oil-whirl-whip
https://www.turbomachinerymag.com/differentiating-between-fluid-induced-instability-oil-whirl-and-oil-whip-and-a-rub/
https://www.researchgate.net/publication/292996114_Faults_detection_in_gas_turbine_rotor_using_vibration_analysis_under_varying_conditions

It looks like these 2 excellents articles are describing what seems to occur at your site/unit.

Please have a carreful read on it.

A spectrum may definitely point the location and amplitude of the Bearing n°1 vibrations on this unit.
Here is an excellent artcile from Control.com :
https://control.com/textbook/machine-vibration-measurement/vibration-physics/



I am sure that this will help you !
ControlsGuy25.
Hello harsh1104

Can you make a feedback on my last post, it would be grateful to do such thing .

ControlsGuy25.
 
Hello harsh1104

Can you make a feedback on my last post, it would be grateful to do such thing .

ControlsGuy25.
Hello all,

Sorry mate, I was out and got got stuck in some issues.

There is no key phasor installed in the system so, I was unable get bode plot, shaft center line and polar plot.
We are trying to arrange and connect external key phasor so I can get these data.

Currently, we are working on to check oil pressure and other oil characteristics to identify Oil Whirl / Oil Whip situation.

Next plan is to get new data for further analysis. Once I got that data I will let you guys know.

What information you suggest that I should collect with data Or any particular type of data which can be useful?

Thank you
 
Hello all,

Sorry mate, I was out and got got stuck in some issues.

There is no key phasor installed in the system so, I was unable get bode plot, shaft center line and polar plot.
We are trying to arrange and connect external key phasor so I can get these data.

Currently, we are working on to check oil pressure and other oil characteristics to identify Oil Whirl / Oil Whip situation.

Next plan is to get new data for further analysis. Once I got that data I will let you guys know.

What information you suggest that I should collect with data Or any particular type of data which can be useful?

Thank you
Hello All

No problem Mate! Hoping that troubleshooting activity on this issue is improving at your site !

I suggest you to have a look, on this excellent video on how to configure Keyphaser and other proximitor:

It is done on Bently nevada 3500 system but Your system is ADRE , so I do not knw if there are similarity between each system configuration.

It is for information .

Then you should be able to perform, vibration analysis as I explained you on my previous post.

Thank you for your feedback !

ControlsGuy25.
 
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