Greetings ...

In najaf gas power plant-Iraq, we have aunit designed by ALSTOM type GT8C2 55MW

cotrol system ABB Egatrol AC160

This unit consist of 18 combustion chambers .. in the center of combustion ( pulstion sensor type cp10x)
kindly I would like to inquire about a problem that occurred in reading pulsation sensor , which is the reading not stable , when the unit is in operation as when the load is gradually increased , the values rise normally

the main problem .. when the load is raised to 40MW the problem it begin , as the value of pulsation is normal , after a certian period the value of pulsation is fluctuate and swift up 40mbar and down 28mbar

does the control valve and Temp. after turbine TAT related to pulsation ?

please help me to understand the philosophy of the pulsation sensor and solve problem

I attached picture to explain the status

 

Greetings


I would be glad to try to support you from France!

Well what is OEM of the vibrometer Called ABE 028 ?

Here some notes to understand better on puslation vs emissions ..

Lean premixed combustion has become state of the art technology in gas turbines for power generation because of its very low emission potential in the context of tightening pollutant emissions regulations. Lean premixed combustion is yet also prone to combustion instabilities, resulting in thermo-acoustically induced acoustic pressure oscillations (pulsations). Understanding pulsation behavior over an enginés lifetime is of interest to accurately monitor the engine status, as wear and degradation typically affect combustion behavior and result in changes of both pulsations and emissions. Such improved understanding can be exploited for optimizing both the engine operation concept and the design of relevant hardware parts. In return, pulsation and hardware optimization may lead to reduced degradation and thus inherently more robust long-term operational behavior. The study presented here is conducted for one specific gas turbine of GE’s GT24/GT26 fleet with sequential annular combustion. Based on operational data of the examined gas turbine, a semi-empirical modeling approach is introduced to describe the pulsations measured in the first (EV) combustion chamber. The target is to reproduce measured pulsation amplitudes as well as their different behaviors with engine load. The modeling presented here has been focused on pulsations in a distinctive frequency range below 1kHz. A model based on a small set of data obtained from initial commissioning is able to represent the pulsation behavior within a normalized root mean square error of 11%. Validation with long-term engine data shows that predicted pulsation levels are reasonably matching the initial operation period but increasingly deviate with engine operating time. By using additional data from later engine commissioning and adjustments, the robustness of the model is sensibly increased. Model accuracy on the training dataset remains similar at around 11%, but validation on the long-term data shows a significant decrease of the normalized root mean square error from over 21% to below 16%. Additional model improvements to further reduce prediction errors on long-term data have been also identified.


I will review the documents that you shared and come back with more advices..

Regards,

@ControlsGuy25

 

Did you check the all loop operating correctly

I see that there is kind of amplifier in the data acquisition chain...

Do you ok with the charge amplifier IPC620/628 also is mentionned in the manual ? would be good to ensure that it is ok


Does the sensor need to be calibrated ? if yes when did you perform last calibration?


Do you and can you share a P&IDs for the mentionned devices?

Is there any alarms annunciated for the behavior of the sensor?

 

The pulsations in a gas turbine combustor are usually measured directly inside the combustor in order to have an accurate measurement across the full frequency spectrum of the pulsations. The conversion of the physical hot gas pressure fluctuation into an electric output signal (high frequency, voltage or current or digital) is performed by a high temperature dynamic sensor (microphone, dynamic pressure transducer, dynamic pressure pick-up, piezo-electric, piezo-resistive, capacitor, strain gage, optical or any other principle), which is combined with suitable signal conditioning (the specific working principle of the sensor is not relevant to the invention disclosed below).

 

Pulsation monitoring on gas turbines is required because the combustion is operated close to the lean extinction limit to reduce emissions. The combustion flame instabilities are interacting with the flow and generate powerful acoustic waves. These waves excite the thermally highly loaded structures of the combustor. If the mechanical vibrations of combustor hot gas parts match in some ways with the acoustic pulsation load, significant wear, leading to a lifetime reduction or even immediate failure, occurs.

 

Pulsation measurement equipment is an integral part of a gas turbine protection system. The purpose of the equipment is to supervise combustion phenomena like pulsation (screeching, rumbling, humming, etc.) to cause an immediate engine shut down or to initiate a change in the engine operation point in the event of sudden high pulsations or long lasting moderate pulsation levels in order to protect the engine from severe damage.

 

Have a good and careful read on this article ( all is well explained on Pulsation measuring/protection:

https://patents.google.com/patent/US20120279229

 

Greetings


I would be glad to try to support you from France!

Well what is OEM of the vibrometer Called ABE 028 ?

Here some notes to understand better on puslation vs emissions ..

Lean premixed combustion has become state of the art technology in gas turbines for power generation because of its very low emission potential in the context of tightening pollutant emissions regulations. Lean premixed combustion is yet also prone to combustion instabilities, resulting in thermo-acoustically induced acoustic pressure oscillations (pulsations). Understanding pulsation behavior over an enginés lifetime is of interest to accurately monitor the engine status, as wear and degradation typically affect combustion behavior and result in changes of both pulsations and emissions. Such improved understanding can be exploited for optimizing both the engine operation concept and the design of relevant hardware parts. In return, pulsation and hardware optimization may lead to reduced degradation and thus inherently more robust long-term operational behavior. The study presented here is conducted for one specific gas turbine of GE’s GT24/GT26 fleet with sequential annular combustion. Based on operational data of the examined gas turbine, a semi-empirical modeling approach is introduced to describe the pulsations measured in the first (EV) combustion chamber. The target is to reproduce measured pulsation amplitudes as well as their different behaviors with engine load. The modeling presented here has been focused on pulsations in a distinctive frequency range below 1kHz. A model based on a small set of data obtained from initial commissioning is able to represent the pulsation behavior within a normalized root mean square error of 11%. Validation with long-term engine data shows that predicted pulsation levels are reasonably matching the initial operation period but increasingly deviate with engine operating time. By using additional data from later engine commissioning and adjustments, the robustness of the model is sensibly increased. Model accuracy on the training dataset remains similar at around 11%, but validation on the long-term data shows a significant decrease of the normalized root mean square error from over 21% to below 16%. Additional model improvements to further reduce prediction errors on long-term data have been also identified.


I will review the documents that you shared and come back with more advices..

Regards,

@ControlsGuy25

Thanks alot for your usfel information

 

Thanks alot for your usfel information

Thanks a lot for the feedback

By the way did you troubleshoot that issue..

 

Did you check the all loop operating correctly

I see that there is kind of amplifier in the data acquisition chain...

Do you ok with the charge amplifier IPC620/628 also is mentionned in the manual ? would be good to ensure that it is ok


Does the sensor need to be calibrated ? if yes when did you perform last calibration?


Do you and can you share a P&IDs for the mentionned devices?

Is there any alarms annunciated for the behavior of the sensor?

Did you check the all loop operating correctly

I see that there is kind of amplifier in the data acquisition chain...

Do you ok with the charge amplifier IPC620/628 also is mentionned in the manual ? would be good to ensure that it is ok


Does the sensor need to be calibrated ? if yes when did you perform last calibration?


Do you and can you share a P&IDs for the mentionned devices?

Is there any alarms annunciated for the behavior of the sensor?

Did you check the all loop operating correctly

I see that there is kind of amplifier in the data acquisition chain...

Do you ok with the charge amplifier IPC620/628 also is mentionned in the manual ? would be good to ensure that it is ok


Does the sensor need to be calibrated ? if yes when did you perform last calibration?


Do you and can you share a P&IDs for the mentionned devices?

Is there any alarms annunciated for the behavior of the sensor?

Thanx alot for the useful information and thank you for cooperating with us

Mr.

Did you check the all loop operating correctly

I see that there is kind of amplifier in the data acquisition chain...

Do you ok with the charge amplifier IPC620/628 also is mentionned in the manual ? would be good to ensure that it is ok


Does the sensor need to be calibrated ? if yes when did you perform last calibration?


Do you and can you share a P&IDs for the mentionned devices?

Is there any alarms annunciated for the behavior of the sensor?

Thanks alot for the useful information and thank you for cooperating with us

*Mr. I would like to share with you more details about pulsation sensor
when the unit is turned on , we find the third value of the pulsation sensor drops to less than 5mbar after the unit stop at 2880 RMP after closing Blow of Valve

and the trip occure because the operating conditions and program conditions must be the lowest value 5mbar , and do not allowed pass operating because the reading at begin operation is less than 5 mbar
*you mentioned the pulsation sensor was calibrated or not
How do we calibrate it ?
in user manual he says that the sensor is calibrated by factory , I attched pic.

*we also replaced the Amplifier and problem was not solved

*importent Ques.

How to check the loop circuit and what the values that should be given when test and I attched pic.

 

HI

Thank you for the feedback!

When i referred to calibration of the sensor it was because I was only asking if that sensor used to be calibrated at site..

I will do some investigation on how to solve this issue..

What is OEM of the Vibro meter ? Is that old Meggit device

I use to work on new Meggit VM600 vibro meter looks like this one is bit older ...

Also what is ABB control system installed on this unit?

 

A dynamic pressure sensor is fitted to each combustor on most modern gas turbines to measure pressure pulsations and combustion dynamics. This is because the turbines burn fuel as lean as possible to reduce emissions to environmentally acceptable levels, but in so doing create metastable flame conditions and corresponding pressure pulsations that will damage and even destroy combustors if left unchecked.


The characteristic frequencies associated with these metastable conditions vary according to manufacturer and combustor. By tuning the monitoring system to these characteristic frequencies, the damaging pulsations can be detected and the fuel/air mixture adjusted to an operating point where the combustor will not be damaged.


The dynamic pressure sensors are thus used as part of a closed-loop control system that keeps combustion from persisting in a state that will damage the combustors. Highly sophisticated filtering and detection is used, as provided by the monitoring system. The dynamic pressure sensors are mounted in extreme environments where temperatures of up to 650° C and billions of pressure cycles must be endured.

 

Have a careful read on this very interesting article it clearly describe the Pulsations protection philosohy *
https://patents.google.com/patent/US7751943

Sound like you can at least try to simulate puslations by Frequency generator like..on the closed loop signal to the vibrometer

Do you have the Vibrmeter manual available

 

 

HI

Thank you for the feedback!

When i referred to calibration of the sensor it was because I was only asking if that sensor used to be calibrated at site..

I will do some investigation on how to solve this issue..

What is OEM of the Vibro meter ? Is that old Meggit device

I use to work on new Meggit VM600 vibro meter looks like this one is bit older ...

Also what is ABB control system installed on this unit?

Oh ok i see that it is EGATROL ( ABB advant platform for the Control system)

 

Best thing would be to check 4-20 mA signals sent to EGATROL like Pulsation High /Low /Middlea and data acquisition signal status if ok