Frame 9e Heavy Duty Gas turbine fuel consumption

In which Mode Frame 9e heavy duty Gas turbine fuel consumption is more for a given part load assuming other parameters constant? Is it simple cycle mode or Combine cycle mode?
 
In which Mode Frame 9e heavy duty Gas turbine fuel consumption is more for a given part load assuming other parameters constant? Is it simple cycle mode or Combine cycle mode?
Look at the frame 9E FACT sheet from OEM ...actually look at the heat balance and eficiency for both mode, you will have an answer for this question
 
Look at the frame 9E FACT sheet from OEM ...actually look at the heat balance and eficiency for both mode, you will have an answer for this question
Thank you for your response.

In fact sheet, all data mentioned are for base load condition and in case of Combined cycle all data are about net effciency.
Since at base load IGV will be in fully opened condition so turbine efficiency will be same in both case (excluding HRSG). I am seeking information regarding fuel consumption at part load condition in simple cycle and combine cycle. In which case ther will be more fuel consumption.
Reason for seeking this information:
I am working in power plant at one of the Refinery of IOCl. Some times in our plant there is execess generation of Refinery Flue gas. This excess RFG is wasted in Flare. In order to utilize excess RFG, my idea is to operate gas turbine with IGV modulation off condition at certain load where HRSG temp can be maintained through extra FG consumption. So I just wanted to know, with IGV modulation off whether gas turbine will require less fuel or more for a given part load compare to IGV modulation on.
 
Thank you for your response.

In fact sheet, all data mentioned are for base load condition and in case of Combined cycle all data are about net effciency.
Since at base load IGV will be in fully opened condition so turbine efficiency will be same in both case (excluding HRSG). I am seeking information regarding fuel consumption at part load condition in simple cycle and combine cycle. In which case ther will be more fuel consumption.
Reason for seeking this information:
I am working in power plant at one of the Refinery of IOCl. Some times in our plant there is execess generation of Refinery Flue gas. This excess RFG is wasted in Flare. In order to utilize excess RFG, my idea is to operate gas turbine with IGV modulation off condition at certain load where HRSG temp can be maintained through extra FG consumption. So I just wanted to know, with IGV modulation off whether gas turbine will require less fuel or more for a given part load compare to IGV modulation on.
Thanks for these clarifications..
In fact one should get access to the plant heat&Mass balance.. So did you search on that way...
 
Have a study on the FCP (fuel charged to Power) ...there is formula explained on OEM GER-3574G document , and other inetresting informations regarding fuel consumption ...


Depending on type of HRSG ( supplementary fired "like duct burner type"/unfired)...

Do not hesitate to share here your opinion..

James
 
aksm238,

When operating at Part Load in Combined Cycle mode at a particular load the fuel consumption will be slightly higher than when the turbine is being operated at the same load in Simple Cycle mode. That’s because the air flow is being restricted by closing the IGVs to increase the exhaust temperature which reduces the mass flow through the gas turbine so to achieve the same load as when the IGVs are not being closed to increase exhaust temperature more fuel is required.

The above presumes the back pressure on the gas turbine exhaust is not significantly different when operating in either Combined- or Simple Cycle modes, and the inlet air temperature is the same and the inlet air filter differential pressure is the same and the IGVs and axial compressor are equally clean (or dirty). AND the fuels being burned have the same BTU content.

You need to factor in any difference in heating values between the two fuels. There are process plants that burn waste gas, often by mixing it with natural gas, but the analysis of fuel nozzle orifice sizing and fuel control valve sizing and required or maximum flow-rates and fuel pressures should be done by the OEM or a firm with similar combustion knowledge and capabilities. It’s not just as simple as connecting a pipe from the flare to the turbine and opening a valve.

And there’s also the maximum available quantity available for burning.

I have seen refineries that use an electric motor-driven compressor to raise the waste gas pressure and store it in suitable vessel until there is a sufficient quantity to burn for a period of time. But that requires energy (for the compressor), and a storage vessel for combustible gas, and a delivery/regulating system. All of which require money and engineering and space.

Doing this kind of analysis is not too difficult if a few presumptions are made, but the devil is in the details, as they say.

Hope this helps! Good on you, though for the initiative to be thinking of how to use waste gas and reduce emissions and be more efficient.
 
aksm238,

When operating at Part Load in Combined Cycle mode at a particular load the fuel consumption will be slightly higher than when the turbine is being operated at the same load in Simple Cycle mode. That’s because the air flow is being restricted by closing the IGVs to increase the exhaust temperature which reduces the mass flow through the gas turbine so to achieve the same load as when the IGVs are not being closed to increase exhaust temperature more fuel is required.

The above presumes the back pressure on the gas turbine exhaust is not significantly different when operating in either Combined- or Simple Cycle modes, and the inlet air temperature is the same and the inlet air filter differential pressure is the same and the IGVs and axial compressor are equally clean (or dirty). AND the fuels being burned have the same BTU content.

You need to factor in any difference in heating values between the two fuels. There are process plants that burn waste gas, often by mixing it with natural gas, but the analysis of fuel nozzle orifice sizing and fuel control valve sizing and required or maximum flow-rates and fuel pressures should be done by the OEM or a firm with similar combustion knowledge and capabilities. It’s not just as simple as connecting a pipe from the flare to the turbine and opening a valve.

And there’s also the maximum available quantity available for burning.

I have seen refineries that use an electric motor-driven compressor to raise the waste gas pressure and store it in suitable vessel until there is a sufficient quantity to burn for a period of time. But that requires energy (for the compressor), and a storage vessel for combustible gas, and a delivery/regulating system. All of which require money and engineering and space.

Doing this kind of analysis is not too difficult if a few presumptions are made, but the devil is in the details, as they say.

Hope this helps! Good on you, though for the initiative to be thinking of how to use waste gas and reduce emissions and be more efficient.

Thank you for your response CSA. I have learned a lot from your posts.

And yes in this case, operating Gas turbine with IGV modulation off will depend on high RFG generaton cases only and all other parameters will remain same.

I was wondering, is there any curve available through which I can quantify the differential fuel consumption.
I don't have any data for simple cycle mode opearation for our frame 9e Gas turbines.
I have already contacted GE representatives but they don't respond very well.

Arun
 
Have a study on the FCP (fuel charged to Power) ...there is formula explained on OEM GER-3574G document , and other inetresting informations regarding fuel consumption ...


Depending on type of HRSG ( supplementary fired "like duct burner type"/unfired)...

Do not hesitate to share here your opinion..

James
Thanks alot James for the information. I will surely check it out.

Arun
 
GE-design heavy duty gas turbines supplied with Mark* turbine control systems are provided with a document called the 'Control Specifications.' Prior to Mark V, there were three parts of the Control Specifications: Control System Settings, Control System Adjustments, and Control Sequences. Beginning with late versions of the Mark IV, the Control Specification was reduced to just one document: the Control Specification. The information you seek is in Sect. 05, Fuel Specifications of the Control Systems Settings portion of the Control Specification, or just the Control Specification for later versions of the Mark IV and newer versions of the Mark*. There are sections for liquid fuel and gas fuel (if the unit burns both) and there is a sub-section in each which lists expected (design) fuel flow-rates for various operating conditions, starting, FSNL (Full Speed-No Load), 25-, 50-, 75- and 100% of rated load.

That's a good place to start, but you also need to know a lot about the RFG you want to burn. For example, if the BTU content is significantly different the fuel control/delivery system may have to be completely duplicated if you want to switch completely over to RFG. As I wrote, there are units which burn a mixture of RFG and natural gas--but it has to be mixed in the right proportions. The pressures of the two gases have to be such that there can be no reverse flows.

You need to look at the Fuel Specifications sub-sections of the Control Specification. That's all I can suggest.

Best of luck!
 
askm238,

I don't think the difference in fuel is significant. The heat rate goes down when the unit is operating in Combined Cycle mode. The gas turbine efficiency goes down, but the overall plant thermal efficiency goes up because of the increased steam production and temperature.

I'm sure there's probably a combined cycle curve somewhere, but I've never seen one. GE publishes a LOT of documents about performance and heat rate, but I can't direct you to the exact one(s) which might have the information you seek.
 
aksm238,

Something about your query has been bothering me, and I might have discovered why.

You want to turn IGV Temp Control OFF to reduce fuel consumption which will reduce exhaust temperature for a given load, and then add RFG to raise the exhaust temperature back to what it was. Is that correct?

I don’t understand how the exhaust temperature will be controlled and limited while injecting RFG. And injecting RFG will also cause the load to increase. So if the idea is to maintain a constant load then the natural gas flow will have to be reduced even further.

Whereas when IGV Temp Control is turned ON and the load setpoint is constant the natural gas flow will have to increase (slightly) to maintain load. When IGV Temp Control is ON the exhaust temperature doesn’t increase much because the fuel flow increases, the exhaust temperature increases because the air flow through the turbine decreases—which decreases the mass flow through the machine which makes the power decrease but in order to maintain the same load as when IGV Temp Control is OFF the fuel flow has to increase.

If you want to burn RFG to reduce natural gas flow (and I’m presuming the unit burns natural gas—you’ve never said what the primary fuel is) you don’t have to do anything to IGV Temp Control—just start adding RFG and the turbine control system will do it’s thing, maintaining exhaust temperature and the load setpoint while reducing primary fuel flow. No extra steps would be required.

That sounds simple, and from a exhaust temperature and load control setpoint it is. But there’s a lot more to it. RFG probably also has some undesirable constituents which may not always be in the same proportions and which may cause problems with combustion and/or turbine hardware. This is yet another reason why the OEM or someone similar needs to review the fuel constituents and make sure it is safe to burn in the unit. And then devise a suitable method to introduce RFG to the combustion system.

But turning IGV Temperature Control ON or OFF isn’t the way to achieve what you seem to be aiming to do—reduce primary fuel flow by burning RFG while maintaining exhaust temperature and load. Just “supplement” the primary fuel flow with RFG and leave everything else alone to do its jobs.

That’s if I understand what you’re trying to do.

Best of luck!
 
aksm238,

Something about your query has been bothering me, and I might have discovered why.

You want to turn IGV Temp Control OFF to reduce fuel consumption which will reduce exhaust temperature for a given load, and then add RFG to raise the exhaust temperature back to what it was. Is that correct?

I don’t understand how the exhaust temperature will be controlled and limited while injecting RFG. And injecting RFG will also cause the load to increase. So if the idea is to maintain a constant load then the natural gas flow will have to be reduced even further.

Whereas when IGV Temp Control is turned ON and the load setpoint is constant the natural gas flow will have to increase (slightly) to maintain load. When IGV Temp Control is ON the exhaust temperature doesn’t increase much because the fuel flow increases, the exhaust temperature increases because the air flow through the turbine decreases—which decreases the mass flow through the machine which makes the power decrease but in order to maintain the same load as when IGV Temp Control is OFF the fuel flow has to increase.

If you want to burn RFG to reduce natural gas flow (and I’m presuming the unit burns natural gas—you’ve never said what the primary fuel is) you don’t have to do anything to IGV Temp Control—just start adding RFG and the turbine control system will do it’s thing, maintaining exhaust temperature and the load setpoint while reducing primary fuel flow. No extra steps would be required.

That sounds simple, and from a exhaust temperature and load control setpoint it is. But there’s a lot more to it. RFG probably also has some undesirable constituents which may not always be in the same proportions and which may cause problems with combustion and/or turbine hardware. This is yet another reason why the OEM or someone similar needs to review the fuel constituents and make sure it is safe to burn in the unit. And then devise a suitable method to introduce RFG to the combustion system.

But turning IGV Temperature Control ON or OFF isn’t the way to achieve what you seem to be aiming to do—reduce primary fuel flow by burning RFG while maintaining exhaust temperature and load. Just “supplement” the primary fuel flow with RFG and leave everything else alone to do its jobs.

That’s if I understand what you’re trying to do.

Best of luck!
I am so sorry for not able to put my facts clearly.
We have 03 nos. of Frame 9e Gas turbine with HRSG.
Gas Turbine Capacity: 103 MW (Primary fuel Naptha and start up fuel Diesel
HRSG capacity : 220 TPH with supplymentry firing. (Available fuels for supplymentry firing are RFG, Diesel,NAPTHA)
Presently we operate GT with IGV Control On at partial load(mostly 70-80 MW)

"You want to turn IGV Temp Control OFF to reduce fuel consumption which will reduce exhaust temperature for a given load, and then add RFG to raise the exhaust temperature back to what it was. Is that correct? " It's partially correct.

I want to turn off IGV Temp Control to reduce fuel consumption in Gas turbine and to compensate reduced exhaust temperature additional RFG will be added in HRSG as supplymentry fuel. There by I can control exhaust temp and save the RFG from forced flaring.

Thank you.
 
Thats why I mentionned/asked on my last post ,if there was supplementary firing see following elements below :

Have a study on the FCP (fuel charged to Power) ...there is formula explained on OEM GER-3574G document , and other inetresting informations regarding fuel consumption ...


Depending on type of HRSG ( supplementary fired "like duct burner type"/unfired)...

Do not hesitate to share here your opinion..

James


So now you jsut come and reply you got such HRSG....

My friend be more/better reactive otherwise i cannot participate more on this thread!

I am sure that you can understand my position.

James
 
I am so sorry for not able to put my facts clearly.
We have 03 nos. of Frame 9e Gas turbine with HRSG.
Gas Turbine Capacity: 103 MW (Primary fuel Naptha and start up fuel Diesel
HRSG capacity : 220 TPH with supplymentry firing. (Available fuels for supplymentry firing are RFG, Diesel,NAPTHA)
Presently we operate GT with IGV Control On at partial load(mostly 70-80 MW)

"You want to turn IGV Temp Control OFF to reduce fuel consumption which will reduce exhaust temperature for a given load, and then add RFG to raise the exhaust temperature back to what it was. Is that correct? " It's partially correct.

I want to turn off IGV Temp Control to reduce fuel consumption in Gas turbine and to compensate reduced exhaust temperature additional RFG will be added in HRSG as supplymentry fuel. There by I can control exhaust temp and save the RFG from forced flaring.

Thank you.
Also, I will save some quantity of Naptha. That is the reason I was interested to quantify the differential fuel in part load with IGV Control On and OFF Mode.
 
Thats why I mentionned/asked on my last post ,if there was supplementary firing see following elements below :

Have a study on the FCP (fuel charged to Power) ...there is formula explained on OEM GER-3574G document , and other inetresting informations regarding fuel consumption ...


Depending on type of HRSG ( supplementary fired "like duct burner type"/unfired)...

Do not hesitate to share here your opinion..

James


So now you jsut come and reply you got such HRSG....

My friend be more/better reactive otherwise i cannot participate more on this thread!

I am sure that you can understand my position.

James
I presumed you understood my query and as per your suggestion I went through the said documents.
But I was more interested to know how much fuel consumption will reduced with IGV Control On and Off mode to Gas turbine.

I am really sorry.
 
aksm238,

I don't think you really understand GE-design heavy duty turbine controls. And, I highly suspected the unit were burning Naphtha but you allowed me to continue with my supposition they were burning natural gas. This is another HUGE difference--Naphtha uses a liquid fuel delivery system and fuel nozzles; RFG--in gaseous form--would use a gas fuel delivery system and fuel nozzles. The nozzles in the combustors can be dual fuel--in fact, they may even be dual fuel (gas/liquid)--but this is another important fact you have not provided. So, if the fuel nozzles in your unit are NOT dual fuel capable--they will have to be made so (changed; upgraded).

When IGV Temp Control is ON, the IGVs are modulated (varied) to make the exhaust temperature as high as allowed for the given operating conditions. Now, if you introduce another fuel into the combustor while the unit is running at Part Load in Pre-Selected Load Control two things will happen. (By the way, I'm presuming you will introduce the RFG using another control system and control valve and control system. The exhaust temperature will start to rise AND the load will increase. Pre-Selected Load Control will reduce the fuel being controlled by the Mark* to reduce the load. The reduction in fuel to reduce the load might be enough to reduce the exhaust temperature so that the IGV position doesn't have to change. If not, then the IGVs will be moved to prevent exhaust over-temperature condition (not an alarm or a trip--just an exhaust temperature higher than the maximum allowed). In this way, everything balances out--the load stays at the desired value, and the exhaust temperature is maximized, and the "primary" fuel (Naphtha???) is reduced as RFG is increased.

Now, let's say you started from a condition where the unit was at Part Load with Pre-Selected Load Control enabled and IGV Temp Control was OFF so exhaust temperature WAS NOT being maximized, and you started adding RFG to the combustor. What will happen is that as RFG is added to the combustor the exhaust temperature will increase--but maybe not to the maximum allowable, and certainly never above the maximum allowable, and load will increase. Pre-Selected Load Control will reduce the fuel being controlled by the Mark* (Naphtha???) to reduce the load, which will also decrease the exhaust temperature. By how much? Impossible to say--but it will decrease a little bit. HOWEVER, there is no way to increase exhaust temperature by simply increasing the RFG while trying to maintain a load setpoint. It's NOT possible to reliably and easily control exhaust temperature--certainly not to maximize it as if IGV Temp Control were ON so if that's what you are trying to achieve--it's going to be darn hard to do simply and reliably.

If you just add RFG to a unit running with Pre-Selected Load Control enabled and IGV Temp Control ON, the Mark* will reduce the amount of fuel it is controlling (to keep the load at the desired setpoint) AND it will modulate (vary) the IGVs to maximize the exhaust temperature. So, you're reducing primary fuel flow (Naphtha???), burning RFG, and maximizing exhaust temperature (using IGV Temp Control).

If you just add RFG to a unit running with Pre-Selected Load Control enable and IGV Temp Control OFF, the Mark* will reduce the amount of fuel it is controlling (to keep the load at the desired setpoint) BUT it will NOT modulate (vary) the IGVs to maximize the exhaust temperature. So, while you'll be reducing the primary fuel flow (Naphtha???) the exhaust temperature won't be increased by much, if at all. If the unit is very near Base Load, exhaust temperature is already at or near maximum allowable anyway, but you haven't told at what load you wish to operate the units, only that they are to be operated at Part Load (which is anything below Base Load).

It seems you think by varying the amount of RFG when IGV Temp Control is OFF you can also control the exhaust temperature (increase it or maximize it). And, unless the unit is near Base Load, that's jut NOT the case. If you want to maximize exhaust temperature you need to have the IGVs in Temp Control (IGV Temp Control ON). Full stop. Period.

If you want to reduce primary fuel flow (Naphtha???) AND maximize exhaust temperature AND maintain a desired load setpoint, you can do that. The Mark* can be programmed for Mixed Fuel Operation (presuming the fuel nozzles are dual fuel-capable, and there is a proper fuel delivery system for each fuel). And, you can select about any mixture of fuels as long as neither fuel is held to any flow less than about 20% of the total (and the Mark* automatically displays flow percentages--it's just up to the operator to make sure that extended operation with either fuel below approximately 20% of total fuel flow is not occurring). And if you work with GE engineering in Belfort, France, they will concoct some deliciously complicated scheme to do this and maybe even automatically prevent extended operation with either fuel at less than approximately 20%. (The 20% value is to make sure there's sufficient fuel flow for proper atomization (pressure atomization), and stable combustion, and it's rough rule of thumb--not cast in concrete. You can BET GE Belfort will have a definite opinion on the exact value....)

This is all doable--but not in the way you seem to want to do it. Let the Mark* do it for you. When you want to run a second fuel in mixed fuel operation AND maximize exhaust temperature AND maintain a desired load--the Mark* can do it. It's not difficult; it's even been done many times before. You don't have to re-invent the wheel because you think you have a better idea (the first one you came up with--which seems to be based on a misunderstanding of GE heavy duty gas turbine controls philosophy and schemes).

You can try this without GE's help (or without a similar engineering company's help) but I can pretty much guarantee it's not going to work the way you are describing you want it to work.

Having said all of the above, if you work with GE Belfort, they absolutely LOVE to throw out proven control schemes used for decades and design extremely complicated new control schemes to do the same thing as they are replacing. (In other words, they LOVE to reinvent the wheel--and get paid to do it!)

Best of luck.

I'm done with this tread, too. Can't add any more, and I don't like to be guessing and I'm getting tired of asking a lot of questions about things which could/should have been provided in the original post (like what fuel is being burned; what fuels the unit is capable of burning; types of HRSGs; and so on).
 
Okay Aksm238 Thanks for clarifying the situation

The original poster Aksm238, idea is to use RFG for HRSG duct burners/supplementary firing.... Not on GT combustion chamber....
Aksm238 got a original idea but the way it is presented is little bit chaotic.. But no problem I understood what he's intending to do..
 
Okay Aksm238 Thanks for clarifying the situation

The original poster Aksm238, idea is to use RFG for HRSG duct burners/supplementary firing.... Not on GT combustion chamber....
Aksm238 got a original idea but the way it is presented is little bit chaotic.. But no problem I understood what he's intending to do..
For some strange reason, I didn't see that last paragraph when I read the askm238's response this morning. And, to the moderators, I don't know how to capture it because when I first read the thread I don't know something's missing (like the last paragraph, sometimes two). This isn't a one-off experience for me is what I'm trying to say. It happened more when I use an Android phone, and lately I've been switching web browsers on my desktops/laptops trying to find one browser I want to stick with (I've been trying out Brave, Edge, and my old fave Firefox, as well as Google Chrome--but I tend to think Google already knows too much about all of us!!!). ALL have LOTS of different configuration/choices for trying to limit pop-ups and tracking and that's all I'm really trying to do. But, choices and configurations even change with different versions of the same browser (I know--it's an "improvement"). Changing browsers shouldn't be a problem, but I have seen it both on Android phones and on Windows-based PCs.

MOST HRSG auxiliary firing systems I have seen would not allow firing unless the GT was at Base Load--not all, but most. I think it has something to do with the available oxygen, which is high to begin with, but I'm told with some burner designs it needs to be as high as possible.

ControlsGuy25, working with/for GE Belfort as much as you seem to have has apparently allowed you to be better at deducing and understanding whacko ideas and schemes. I understand how askm238's scheme might work now, but I think it's iffy at best. I wonder if the auxiliary burners are really capable of burning RFG at this time, and if so, why hasn't his scheme been tried? He could monitor GT fuel flow with IGV Temp Control ON and then OFF (allow time for internal GT temps to stabilize!) to see how much fuel flow changes. That could even be done at any time. Real world data is so much better than computer-generated graphs and curves.
 
For some strange reason, I didn't see that last paragraph when I read the askm238's response this morning. And, to the moderators, I don't know how to capture it because when I first read the thread I don't know something's missing (like the last paragraph, sometimes two). This isn't a one-off experience for me is what I'm trying to say. It happened more when I use an Android phone, and lately I've been switching web browsers on my desktops/laptops trying to find one browser I want to stick with (I've been trying out Brave, Edge, and my old fave Firefox, as well as Google Chrome--but I tend to think Google already knows too much about all of us!!!). ALL have LOTS of different configuration/choices for trying to limit pop-ups and tracking and that's all I'm really trying to do. But, choices and configurations even change with different versions of the same browser (I know--it's an "improvement"). Changing browsers shouldn't be a problem, but I have seen it both on Android phones and on Windows-based PCs.

MOST HRSG auxiliary firing systems I have seen would not allow firing unless the GT was at Base Load--not all, but most. I think it has something to do with the available oxygen, which is high to begin with, but I'm told with some burner designs it needs to be as high as possible.

ControlsGuy25, working with/for GE Belfort as much as you seem to have has apparently allowed you to be better at deducing and understanding whacko ideas and schemes. I understand how askm238's scheme might work now, but I think it's iffy at best. I wonder if the auxiliary burners are really capable of burning RFG at this time, and if so, why hasn't his scheme been tried? He could monitor GT fuel flow with IGV Temp Control ON and then OFF (allow time for internal GT temps to stabilize!) to see how much fuel flow changes. That could even be done at any time. Real world data is so much better than computer-generated graphs and curves.
Csa,

You are most welcome.
 
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