A
during Gas turbine start up once the unite reaches 60% of speed the exh. temp.decrease.
my question why this happens.
my question why this happens.
B
bcthakkar
If you closely monitor it happens when IGV starts opening from 33 % to 57 %. Because of more air flow, ex. temp. decrease.
As usual, Ayed's post is incomplete as he hasn't told us anything about the unit at his site (Frame size; control system; etc.).
I believe he has indicated in past posts that the unit at his site is a GE-design Frame 9E. Most of these units have electric motors for the starting means, driving the shaft through a Voith torque converter. At approximately 60% speed (1800 RPM) the torque converter is de-pressurized (20TU-1 is de-energized, effectively eliminating any assist from the starting means motor).
At this point the turbine is said to be "self-sustaining"; that is, the power necessary to maintain speed, and continue acceleration, comes entirely from the fuel being burned in the combustors and the expansion of the hot gases in the turbine section.
It has been my experience that at the point that the torque assist of the Frame 9E starting means is removed that the exhaust temperature drops slightly, or, at least the rate of increase tends to slow. (This exhaust temperature characteristic seems to be slightly different from Frame 5s and Frame 6Bs which employ a different type of starting sequence and use a jaw-type or SSS (Shifting, Self-Synchronizing) clutch.)
The modulated IGVs of most Frame 5, Frame 6B, Frame 7E/EA and Frame 9E GE-design heavy duty gas turbines don't typically don't begin to open from the fully closed position (usually 34 DGA, DeGrees Angle) until around 78-82% speed, at which time the exhaust temperature drops even further and CPD starts to increase even more.
Ayed, if the turbine at your site is not a Frame 9E then the above is not entirely, 100% applicable, and you would need to provide more information. And, if you've used the 'Search' feature of control.com to find other GE-design heavy duty gas turbine-related threads, then you will have noticed that many people take the time to provide feedback about the information provided in response to their question or query or problem. That feedback allows other readers to know if the information was useful or not, and helps them to know if it may be applicable to their situation or question. "Feedback is our most important contribution!"(c) here at control.com because it provides everyone (posters, responders, readers) if the information was helpful.
And it's just common courtesy to let someone know if they were helpful. Remember, the people providing responses to your questions are paid exactly the same amount as you paid to post your query. Nothing. So, a little courtesy goes a long way.
Ayed, please help us help you better in the future by providing at least minimal information about the unit and conditions when posting your questions to the site. Those who provide the most information usually get the best responses. Because this site doesn't have avatars or a page where we can see information about you or your site or the unit at your site that you can post once for everyone to refer to, we can't know anything except what you tell us.
I believe he has indicated in past posts that the unit at his site is a GE-design Frame 9E. Most of these units have electric motors for the starting means, driving the shaft through a Voith torque converter. At approximately 60% speed (1800 RPM) the torque converter is de-pressurized (20TU-1 is de-energized, effectively eliminating any assist from the starting means motor).
At this point the turbine is said to be "self-sustaining"; that is, the power necessary to maintain speed, and continue acceleration, comes entirely from the fuel being burned in the combustors and the expansion of the hot gases in the turbine section.
It has been my experience that at the point that the torque assist of the Frame 9E starting means is removed that the exhaust temperature drops slightly, or, at least the rate of increase tends to slow. (This exhaust temperature characteristic seems to be slightly different from Frame 5s and Frame 6Bs which employ a different type of starting sequence and use a jaw-type or SSS (Shifting, Self-Synchronizing) clutch.)
The modulated IGVs of most Frame 5, Frame 6B, Frame 7E/EA and Frame 9E GE-design heavy duty gas turbines don't typically don't begin to open from the fully closed position (usually 34 DGA, DeGrees Angle) until around 78-82% speed, at which time the exhaust temperature drops even further and CPD starts to increase even more.
Ayed, if the turbine at your site is not a Frame 9E then the above is not entirely, 100% applicable, and you would need to provide more information. And, if you've used the 'Search' feature of control.com to find other GE-design heavy duty gas turbine-related threads, then you will have noticed that many people take the time to provide feedback about the information provided in response to their question or query or problem. That feedback allows other readers to know if the information was useful or not, and helps them to know if it may be applicable to their situation or question. "Feedback is our most important contribution!"(c) here at control.com because it provides everyone (posters, responders, readers) if the information was helpful.
And it's just common courtesy to let someone know if they were helpful. Remember, the people providing responses to your questions are paid exactly the same amount as you paid to post your query. Nothing. So, a little courtesy goes a long way.
Ayed, please help us help you better in the future by providing at least minimal information about the unit and conditions when posting your questions to the site. Those who provide the most information usually get the best responses. Because this site doesn't have avatars or a page where we can see information about you or your site or the unit at your site that you can post once for everyone to refer to, we can't know anything except what you tell us.
A
Ayed
the unites that we have are GE frame 7E
three stages.
mark V is the controller
three stages.
mark V is the controller
