7FA GT Classic Re Imagined - GEA17911

©2009 General Electric Company. All Rights Reserved. This material may not be copied or

distributed in whole or in part, without prior permission of the copyright owner.

The 7FA Gas Turbine “A Classic Reimagined”

GE Gas Turbine Technology SymposiumGreenville, SC

October 2009

Russ Martin60 Hz Product Manager - Advanced TechnologyHeavy-Duty Gas Turbine Combined Cycle

Jim DonohueMarketing Program Manager - Advanced TechnologyHeavy-Duty Gas Turbine Combined Cycle

GE Energy

©2009 General Electric Company. All Rights Reserved. This material may not be copied or distributed in whole or in part, without prior permission of the copyright owner.

i

I. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

II. The 7FA Model Series. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1GE F Series Gas Turbine Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1GE F Series Technology “Firsts” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1The Fleet with the Most Experience. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

III. 7FA Platform Evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Naming Progression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Performance Evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

IV. The 7FA Story Continues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Value Proposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Maintainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

V. Reference Plant Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

VI. Proven Technology and Experience. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Turbine Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

VII. Validation Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Component Level Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12System Level Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

VIII.Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Contents


1

The 7FA Gas Turbine: “A Classic Reimagined”

I. IntroductionToday’s power generators find themselves in an uncertain world. Greenhouse gas legislation, fuel prices, renewable

portfolio standards, and financing constraints are but a few of the issues they face. In response to these demands, GE

has continued to evolve its F-class technology, which has been an industry standard for reliable, flexible, and economical

power generation for almost two decades.

The newest addition to GE’s F-class gas turbine portfolio, the 7FA.05 version, delivers greater output and efficiency while

maintaining leadership in reliability, availability and the operational flexibility power generators need to achieve greater

revenue in all operating modes. In developing the newest version of the 7FA, GE has mined the wealth of knowledge that

comes from the largest and most experienced F-class fleet in the industry and combined it with proven technology from

across GE’s broad portfolio of heavy-duty and aeroderivative gas turbines, as well as GE’s aircraft engine models.

II. The 7FA Model Series GE F Series Gas Turbine ExperienceGE’s F gas turbine technology was initially developed in the 1980s. It represented a quantum leap in the operating

temperatures, cooling technology and aerothermal performance of heavy-duty gas turbines. GE’s first F technology

unit entered commercial service on June 6, 1990. As of August 2009, there are more than 700 7FA gas turbines in service

with a cumulative operating experience of more than 19 million fired hours and more than 520 thousand starts. The

hours-based fleet leader has logged more than 126 thousand hours while the starts-based fleet leader has logged

more than 3,400 starts.

7F technology has been scaled to the 50 Hz 9FA machine and the 50/60 Hz 6FA machine. It has also evolved to the

advanced FB technology found in GE’s 60 Hz 7FB and 50 Hz 9FB machines. A grand total of 996 GE F technology units

are now in service with more than 30 million fired hours and 624 thousand starts.

This experience includes operation in duty cycles ranging from peaking to daily start/stops to base load operation as

illustrated in Figure 1.

GE F Series Technology “Firsts”GE has continued to develop the F technology over time, and the 7F has been the first to achieve numerous

F technology firsts:

• F technology gas turbine

• 55% thermal efficiency

• 100% reliability…275 day period

• Single digit emissions for NOx and CO

• 99.4% reliability…F technology record

Model Units Hours Starts

6FA 74 2.6+M 31K

7FA/B 715 19.0+M 520K

9FA/B 197 7.3+M 77K

Table 1. GE F-class operational experience.



2

• Syngas applications

• 700+ units manufactured

• 19+ million operating hours

• 40% load with single-digit emissions compliance

The Fleet with the Most ExperienceTo summarize, GE can confidently say its F technology has:

• The largest fleet

• The most operational experience

• The most reliable fleet

III. 7FA Platform EvolutionNaming ProgressionOver time, as the 7FA evolved, various version and designation nomenclatures have been used to distinguish ratings

and part replacement configurations. In general, the historical “version” progressed as firing temperature incrementally

increased (i.e., 7F, 7FA, 7FA+, 7FA+e), while historical “designations” were assigned depicting frame size, shaft horsepower

and shaft configuration. Going forward, GE has adopted a simplified naming convention as illustrated in Table 2.

The platform will continued to be referred to as the “7FA” model with incremental versions to distinguish significant

rating changes.

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

0

7FA - FA+e/7FB Fleet Experience

Fire

d St

arts

Fired Hours0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 90,000 100,000

Peaking Duty15723% of Fleet

Cycling32647% of Fleet

10 Hours/Start50 Hours/Start7F - FA7FA+ - 7FA+e7FB

Base Load20730% of Fleet

Figure 1. 7FA duty cycle for 2008 (base load, cyclic, peak).


3


Performance EvolutionFigure 2 illustrates the evolution of the 7F technology since its inception. The remainder of this paper focuses on the next

step in the 7FA evolution and how it addresses customers’ needs today and in the future.

IV. The 7FA Story ContinuesValue PropositionGE Energy’s newest version of the 7FA heavy-duty gas turbine, the 7FA.05, delivers greater output and efficiency than

earlier versions of the 7FA, while maintaining leadership in reliability, availability and the operational flexibility power

generators need to achieve greater revenue in cyclic and peaking operation.

To help meet customers’ growing needs to generate more power more efficiently, GE Energy introduces the next

evolution of its industry-leading 7FA heavy-duty gas turbine for the 60 Hz power generation regions. By merging a host

of proven technologies mined from across our product lines, the next evolution of the 7FA now offers improvements in

output, thermal efficiency, operability and lower life-cycle costs, all without compromising the high degree of reliability,

availability, and maintainability (RAM), and operational flexibility historically delivered by GE’s F-class fleet.

Using proven technology from earlier GE models, the 7FA.05 version is coupled with a highly advanced 14-stage axial

compressor, providing enhanced performance, operability, and maintainability, in simple-cycle and combined-cycle

configurations.

220

210

200

190

180

170

160

150

GT

outp

ut (M

W)

Years’88 ’90

7F34.5% Eff.

7FA35% Eff.

7FA+35.7% Eff.

7FA+e36.2% Eff.

7FA.04 Version38.0% Eff.

7FA.05 Version38.5% Eff.

Combustion/HGP

Compressor

’92 ’94 ’96 ’98 ’00 ’02 ’04 ’06 ’08 ’10 ’12 ’14

Figure 2. 7F performance evolution.

Product Model 7F 7FA 7FA 7FA 7FA 7FA

Revised Version 7F.01 7FA.01 7FA.02 7FA.03 7FA.04 7FA.05

Historical Version 7F 7FA 7FA+ 7FA+e - -

Historical Designation PG 7191 PG 7221 PG7231 PG7241 - -

Table 2. 7FA model naming progression.


PerformanceThe improved performance and efficiency of the next evolution of the 7FA gas turbine translates into increased revenue

for power generators. GE’s new 7FA delivers greater output with greater efficiency than earlier versions of the 7FA, without

sacrificing the reliability, availability and operational flexibility customers have come to expect from GE F-class technology.

Especially well-suited for cyclic and peaking projects, the 7FA.05 version can generate more than 625 MW in a 207FA

combined-cycle configuration with 57.5% efficiency, and with the backing of GE Energy’s unsurpassed product support.

The application of a larger, more efficient compressor delivers improved output compared to earlier versions by allowing more

airflow, and enhanced efficiency due to its three-dimensional aerodynamic airfoils and hybrid radial compressor diffuser.

Simple Cycle Combined Cycle*

Output 211 627

Efficiency (%, LHV) 38.5 57.5

Heat Rate (Btu/kW-hr, LHV) 8872 5934

NOx (ppmvd @ 15% O2) 9 2

CO (ppmvd) 9 9

*Combined-cycle values assume gas fuel, ISO base load conditions, 1.5" HgA steam turbine

backpressure, 2x1 combined cycle utilizing a GE 207D-11 ST, SCR, no duct firing and no CO catalyst.

Simple-Cycle Gas Turbine Output. The gas turbine output of the 7FA.05 version is incrementally improved over the 7FA.03

version by +33.6 MW (cold day @ 0°F); +35.8 MW (ISO day @ 59°F); and +37.4 MW (hot day @ 100°F) as shown in Figure 3.

Figures 3 and 5 have a characteristic flat output rating from approximately 59°F to 70°F. In this ambient temperature

region, the 7FA.05 gas turbine operates with slightly closed inlet guide vanes and variable stator vanes, which become

opened fully at approximately 70°F. In the region of constant base load output, the exhaust flow will increase, exhaust

temperature will stay approximately flat, and the exhaust energy will increase.


4

240

220

200

180

160

140

SC O

utpu

t (M

W)

Ambient Temperature (°F)

7FA.05

7FA.04

7FA.03

-20 0 20 40 60 80 100 120

ImprovedHot Day Output

+37.4 MW

Figure 3. Simple-cycle gas turbine output.


5


Simple-Cycle Gas Turbine Efficiency. The gas turbine simple-cycle efficiency of the 7FA.05 version is incrementally improved

over the 7FA.03 version by 1.4 points (cold day @ 0°F); 1.4 points (ISO day @ 59°F); and 1.6 points (hot day @ 100°F) as

illustrated in Figure 4.

Combined-Cycle Gas Turbine Output. The plant output of the 7FA.05 version in a 2x1 configuration is incrementally

improved over the 7FA.03 version by +111 MW (cold day @ 0°F); +98 MW (ISO day @ 59°F); and +105 MW (hot day @ 100°F)

as illustrated in Figure 5.

It is important to note that in a fully duct-fired application, the 7FA.05 version can achieve more than 750 MW in a 207FA

configuration.

40%

39%

38%

37%

36%

35%

34%

SC E

ffic

ienc

y (L

HV)


7FA.05

7FA.04

7FA.03

-20 0 20 40 60 80 100 120

ImprovedEfficiency

+1.4 pt

Figure 4. Simple-cycle gas turbine efficiency.

700

650

600

550

500

450

400

CC N

et O

utpu

t (M

W)

-20 0 20 40 60 80 100 120

7FA.05

7FA.04

7FA.03


ImprovedHot Day Output

+105 MW

Figure 5. Combined-cycle gas turbine output.


*Ecomagination is a trademark of the General Electric Company.


6

Combined-Cycle Heat Rate. The combined-cycle efficiency of the 7FA.05 version in a 2x1 configuration is incrementally

improved over the 7FA.03 version by 1.2 points (cold day @ 0°F); 1.0 points (ISO day @ 59°F); and 1.2 points (hot day @

100°F) as illustrated in Figure 6.

EnvironmentIn today’s world of increased concern over climate change and the inevitable tightening of regulatory requirements, the latest

evolution of the 7FA maintains its legacy DLN2.6 combustion system to further improve emissions and operating flexibility.

Superior Combustion Technology. With its industry-leading DLN2.6 combustion system, and a model-based control

system that enables robust accommodation of ambient condition and fuel composition variations, the 7FA.05 version

produces more power by firing at higher temperatures while producing only single digit NOx and CO emissions—from

49% load up to 100% load.

Ecomagination*. Ecomagination is GE’s commitment to imagine and build innovative technologies that help customers

address their environmental and financial needs, such as the need for cleaner, more efficient sources of energy. To join

the ecomagination portfolio, a system must complete the company’s rigorous internal and third-party environmental

and operational evaluation.

The new 7FA gas turbine is part of GE’s ecomagination portfolio. Its improved efficiency and higher output will result

in less fuel consumption and lower emissions on a MW-hr basis than currently available 7FA gas turbines across the

entire ambient temperature range, while maintaining the operational flexibility needed by customers to respond to

varying electricity demand conditions. A typical customer operating a GE 207FA combined-cycle plant with a 7FA.05

gas turbine instead of a 7FA.03 gas turbine for an equivalent net plant output of 627 MW could avoid the emission of

more than 19,000 metric tons of CO2 per year, equivalent to the emissions of approximately 3,800 cars on U.S. roads.

FlexibilityThe compressor’s three Variable Stator Vane (VSV) stages enhance operational flexibility by allowing the control system

to adjust compressor airflow to accommodate varying fuel and ambient conditions, or in response to changing

operating conditions.

58.0%

57.5%

57.0%

56.5%

56.0%

55.5%

54.5%

CC N

et E

ffic

ienc

y (L

HV)


7FA.05

7FA.04

7FA.03

-20 0 20 40 60 80 100 120

+1.0 pt Improved Hot DayEfficiency

Figure 6. Combined-cycle heat rate.

Improved Operability. GE’s 7FA gas turbine provides the greatest operational flexibility in its class, with proven

performance in applications ranging from combined cycle and cogeneration to simple-cycle peaking. Our flexible

performance features can help customers expand their ability to operate based on their own specific business priorities

and market parameters, largely free from the constraints of equipment limitations.

Turndown capabilities ensure operators can run the turbine at its lowest operating level without turning it off, leading to

reduced fuel costs, reduced maintenance, and avoiding emissions spikes and time delays associated with full start-ups.

As base load gas turbine output grows it becomes more challenging for the combustor to achieve the same absolute MW

level of the prior version. However, in this case it should be noted that the MW turndown spread (i.e., base load to minimum

load) is wider for the 7FA.05 version. This is attributed to the additional flexibility of the compressor Variable Stator Vanes

(VSVs). In the spirit of continually improving its products to satisfy customers’ needs, GE is developing improved turndown

capability technologies that are expected to bring the absolute MW turndown of the 7FA.05 version even lower.

Fast startup capabilities provide the ability to reduce NOx emissions during low load operation, leading to reduced

operating restrictions based on startup NOx limits and savings based on NOx trading credits.

Fuel heating capabilities allow operation on unheated fuel over an expanded portion of the startup sequence, leading

to reduced fuel consumption and reduced startup times for both cold and warm starts.


7


*Ecomagination is a trademark of the General Electric Company.

7FA.05

7FA.04

7FA.03


150

140

130

120

110

100

90

80

70

60

GT

Min

Tur

ndow

n (M

W)

-20 0 20 40 60 80 100 120

Figure 7. Gas turbine turndown.

Table 3. 7FA gas turbine turndown comparison.

Component 7FA.03 7FA.03 w/Extended Turndown 7FA.04 7FA.05

Base Load 175 175 183 211

Min MW 87.5 73.5 97 103

% GT Turndown (ISO) 50% 42% 53% 49%

GT Turndown Spread (ISO) 87.5 101.5 86 108

Improved Dispatchability. For customers considering a cycling power plant, the 7FA.05 version can be outfitted with

Rapid Response, providing fast and reliable starts. Rapid Response is a combined-cycle plant solution that allows

generators to quickly add power-generating capacity during times of peak demand while significantly reducing NOx

emissions (up to 60%) and CO emissions (up to 25%) during each startup.

Fuel Flexibility. The 7FA.05 version is fuel flexible, capable of operating on natural gas fuel with a Modified Wobbe Index

Variation of +/-5% without the need for retuning or other adjustments, and can be also be operated using distillate fuel,

reducing fuel costs by enabling operation with the lowest priced fuel available.

MaintainabilityThe compressor’s field-replaceable blades, along with additional borescope holes that allow for enhanced coverage,

enable improved maintainability and inspection capabilities and result in reduced outage times.

Improved monitoring and diagnostic capabilities are also included through additional sensors and instrumentation that

monitor blade health, along with advanced algorithms that enhance efficiency predictions.

Removable Compressor Blades. The 7FA.05 version compressor supports in-situ removable rotor blades. The enabling

technology is the circumferential dovetail slot design in contrast to an axial dovetail slot design. The circumferential

dovetail design allows the blades to slide circumferentially for removal at designated locations. Blade locks secure

the blades in position.

Improved Inspectability. The 7FA.05 version compressor casing includes improved inspection capability by the addition

and repositioning of borescope holes. The 7FA.05 version has three borescope hole locations on each stage as compared

to two per stage on the prior versions.


Figure 9. Enhanced borescope inspection.

10 O’Clock

2 O’Clock

Top

Visible with Robot

Visible

Borescope Locations

Figure 8. Removable compressor rotor blades.


8

Enhanced Sensors. New and improved GE proprietary sensors have been added to the 7FA.05 version to support improved

measurement accuracy for performance and operability as well as advanced prognostic capability leading to improved

reliability and availability.

• New and improved GE proprietary sensors have been added:

– Corrosion monitoring for inlet filtration effectiveness

– Blade health monitoring for prognostic anomaly detection

– Variable Stator Vane positioning for enhanced performance

• Existing sensors have been improved for enhanced performance:

– Inlet Guide Vane positioning

– Emissions monitoring

– Compressor flow

– Bleed valve flow

Advanced Monitoring & Diagnostics. The 7FA.05 version incorporates new monitoring and diagnostics capabilities

to help operators better characterize the operation of their gas turbines and determine the condition of key components.

This improved capability will enable the Mark* VIe control system to improve performance and provide operators with

unprecedented diagnostic and prognostic capabilities.

V. Reference Plant ConsiderationsThe 7FA.05 version has minimal impact on customers’ existing 7FA reference plant designs. Minor changes are needed to

accommodate the higher airflow, including a slight increase in the size of the inlet and exhaust, but key parameters such

as the required fuel gas pressure and guaranteed noise level remain unchanged.


9


Figure 10. Reference plant design changes.

InletScaled for flow increase

Gas Fuel SystemScaled for fuel flow increase

Cooling and Sealing AirRe-routed piping

ExhaustScaled for flow increase

Gas Turbine BaseReconfigured for VSV/IGV accommodation

Oil PumpsLube and hydraulic scaled for flow

*Mark is a trademark of the General Electric Company.

VI. Proven Technology and ExperienceThe 7FA.05 version builds upon the heritage of proven low risk technology from other GE platforms to achieve a more

efficient, flexible machine. The technologies chosen for the 7FA.05 version have been demonstrated in other GE gas

turbine platforms and leveraged for the 7FA.05 version as depicted in Table 4.

CompressorGE's most advanced high efficiency compressor technology, based on the 6C and H platforms and built with GE Aviation

compressor technology practices, has been incorporated into the new 7FA turbine. The 7FA.05 version technology consists

of 14 stages specifically modeled for a higher flow rate, enabling greater output.

The airfoil design is based on the proven aerodynamic configuration of the 6C. The airfoils utilize a three-dimensional

aerodynamic configuration for improved efficiency. The first three stages of the compressor contain variable stator

vanes that provide the gas turbine with a wider operating envelope. The compressor flow path has been configured to

accommodate inlet conditioning with improved leading edge erosion tolerance.

The rotor is bolted steel construction with two sets of durable concentric tie bolts specifically planned to improve the

aerodynamic flow path. The rotor blades and wheels incorporate a circumferential dovetail that permits removing

the blades without pulling the rotor from the casing, thereby improving maintainability.

The compressor casing has been built to match the rotor and the existing DLN2.6 combustor interface. The casings

accommodate an advanced Blade Health Monitoring (BHM) system for stages 1 through 3. Additional borescope holes

have been included for enhanced inspection coverage.

Table 5 identifies the major components of the compressor and how the technology was borrowed from other GE

platforms. A check mark signifies previous experience with the material used in the 7FA.05 version, whereas a green

shaded background signifies prior model experience.

CombustionThe 7FA.05 version will employ the proven DLN2.6 combustor. The combustor has more than 12 million hours and

350,000 starts of operational experience. Minor modifications to the DLN2.6 combustion system will be required for

improved output and efficiency. Upgraded fuel nozzles will allow for a higher fuel flow rate and the transition-piece

cooling flow has been improved. Combustion lab tests have demonstrated emissions, durability, operability, dynamics

and exit profiles for these minor modifications.



10

Table 4. 7FA.05 model version configured from GE experience base.

Platform Introduction Units Hours Starts Technology Leveraged

B / EA ‘70s 1120 32+ Million 850K+ Materials

7 / 9FA ’91 / ‘92 1170 30+ Million 600K+ All

7 / 9FB ’02 / ‘05 43 190,000+ 5,900+ HGP

7 / 9H ’08 / ‘03 6 32,000+ 150+ Compressor / HGP

6C ‘05 2 57,000+ 470+ Compressor

GE10 ‘03 254 1+ Million 26K+ Compressor

Turbine SectionThe turbine section of the 7FA.05 version capitalizes on the recent 7FA.04 Hot Gas Path advancements. FB technology

and experience have been used in the design. Noted features are:

• Three-dimensional aerodynamics airfoil shapes for the stage 1 nozzle and stage 1 bucket improving efficiency

• More efficient stage loading

• Improved cooling and sealing for improved efficiency

• Improved clearances for improved efficiency

• Nominal Tfire increase that still remains well within the FA experience

Materials. FB materials have been employed for the stage 1 nozzle and stage 1 bucket while H material has been

used for the stage 2 nozzle. The higher temperature-capable materials still operating in FA firing temperatures will further

improve the successful experience of the 7FA wear modes for low cycle fatigue, oxidation and creep, thus supporting

longer life and reduced repair costs.

Configuration. The first and second stages of the turbine section will consist of minor modifications to the 7FA.04 version

hardware to increase the flow passing capability. The third stage and distance piece will utilize a 7F Syngas design. The

turbine casing remains unchanged.


11


Table 5. 7FA.05 version compressor model experience.

Component Comment B/E FA FB 6C H GE10

VSVs 3 Variable Stator Vanes � � �

Rotor Bolted, 2 Tie Bolt Rings � � �

Wheels Circumferential Dovetails � � � � � �

Blades Increased Stage Loading � � � � � �

Casings Match Rotor and DLN2.6 � � � � � �

Diffuser Hybrid Radial Flow Path � � �

Bearings Non-integral w/fwd Case � � � � � �

�= Materials experience, Green = model experience

Table 6. 7FA.05 version combustion model experience.

Component Comment 6/7/9FA Comment

Liner / Flow Sleeve DLN2.6 model � No change

Transition Piece TP cooling pattern adjusted for radial diffuser flow distribution � Minor mod

Caps DLN2.6 model � No change

End Cover DLN2.6 model � No change

Fuel Nozzles Fuel injection peg adjusted for higher fuel flow rate � Minor mod


VII. Validation PlansThe latest evolution of the 7FA gas turbine will be validated via a comprehensive program of component level, system

level, and fleet level testing. GE is the only gas turbine OEM that has the unique combination of aviation, aeroderivative,

and heavy-duty gas turbines product lines. This breadth of model, manufacturing, and operational experience, coupled

with the world-renowned capabilities of our Global Research Centers, enable GE to perform comprehensive validation

testing and pre-and post-test analyses.

Component Level TestingThe first step of the validation testing program is component level testing. Although the 7FA.05 version employs proven

technology, GE recognizes that robust configurations depend upon a rigorous program to ensure all components are

tested in the actual environments they will see in service.

Many of the components used in the 7FA.05 version have been field tested on a retrofit basis in existing 7FA.03 version

machines. Examples of this include the combustor transition piece and combustion liner, which were introduced in 2006

and currently have more than 13.9 million hours and 380 thousand starts.

Other components, such as the compressor diffuser, will be initially tested in test rigs at GE facilities prior to being

incorporated into system level tests.

System Level Testing After component level tests are complete, system level tests are performed in order to fully understand interactions

among components.

As mentioned previously, the DLN2.6 combustor has been slightly modified to accommodate higher mass flow. The

modified combustion system will be tested at the GE Greenville, South Carolina Combustion Laboratory prior to being

incorporated into full unit system tests.

A system level test of the turbine section hot gas path components was conducted in the first half of 2008 as a field

retrofit of an existing 7FA.03 version turbine at a customer site in Asia. These components are expected to accumulate

close to 20,000 hours before the first 7FA.05 version is put into commercial service.

GE is constructing a unique Full-Speed Full-Load test facility at its Greenville facility. The first system to be tested in

this facility will be the 7FA.05 version compressor. Using a unique and proprietary power train, GE will be able to fully

characterize the performance of the compressor, including aeromechanics, performance, and surge line mapping.

Following characterization of the compressor, GE will combine the compressor with the 7FA.05 version DLN2.6 combustion

system and 7FA.05 version turbine section and perform a Full-Speed Full-Load test of the complete 7FA.05 version gas

turbine prior to shipping the first commercial unit. This testing will utilize extensive instrumentation to demonstrate

performance, aeromechanics, combustion dynamics, off-frequency capability, and dual-fuel capability. This validation

approach will enable GE to fully characterize the 7FA.05 version under real-life conditions, but in a laboratory setting.



12

Table 7. 7FA.05 version turbine model experience.

Component Comment B/E 7/9FA 7/9FB 6C 7/9H GE10

Stage 1 7FA.04 version � � � �

Stage 2 7FA.04 version � � � �

Stage 3 7F Syngas version � � � � �


The final stage in the system level testing consists of precision performance testing as part of the normal commissioning

activities and a fleet leader inspection program. This inspection program will consist of advanced Monitoring & Diagnostics,

both onsite and remotely, coupled with a program of enhanced borescope inspections designed to be as unobtrusive to

customer plant operations as possible.

VIII. Conclusion GE’s 7FA is the most experienced F-class gas turbine in the world. The 7FA fleet has more units in service, and has

accumulated more operating hours and starts than any other F-class gas turbine. GE has utilized the wealth of knowledge

that comes from this F-class operating experience and combined it with technology from across GE’s broad portfolio

of heavy-duty and aeroderivative gas turbines, as well as GE’s aircraft engine models, to develop the 7FA.05 version

gas turbine.

The 7FA.05 version has been configured to have a minimal impact on existing customer reference plant designs. Minor

changes are needed to accommodate the higher airflow and associated output, but key parameters such as the required

fuel gas pressure and guaranteed noise level remain unchanged.

The 7FA.05 version delivers increased output and efficiency, which are of course highly valued in today’s competitive

power generation segment, but does so without compromising the world-class operational flexibility, reliability, and

availability of the 7FA. The improved performance and operational flexibility have enabled the 7FA.05 version to become

part of GE’s ecomagination portfolio, a rigorous internal and third-party environmental and operational evaluation.

Prior to delivering the first unit to a customer, the 7FA.05 version will undergo a battery of component level, subsystem

level, and system level tests, culminating in a Full-Speed Full-Load test in a new state-of-the-art test facility being

constructed at GE’s Greenville, South Carolina, gas turbine manufacturing and test center of excellence. This testing

will enable GE to fully characterize the 7FA.05 version under real-life conditions, but in a laboratory setting.

GE’s commitment to the 7FA gas turbine is a testament to the confidence GE has in this industry workhorse to continue

to serve the wide-ranging needs of its customers in an ever changing and extremely competitive segment.


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List of FiguresFigure 1. 7FA duty cycle for 2008 (base load, cyclic, peak).

Figure 2. 7F performance evolution.

Figure 3. Simple-cycle gas turbine output.

Figure 4. Simple-cycle gas turbine efficiency.

Figure 5. Combined-cycle gas turbine output.

Figure 6. Combined-cycle efficiency.

Figure 7. Gas turbine turndown.

Figure 8. Removable compressor rotor blades.

Figure 9. Enhanced borescope inspection.

Figure 10. Reference plant model changes.

List of TablesTable 1. GE F-class operational experience.

Table 2. 7FA model naming progression.

Table 3. 7FA gas turbine turndown comparison.

Table 4. 7FA.05 version configured from GE experience base.

Table 5. 7FA.05 version compressor model experience.

Table 6. 7FA.05 version combustion model experience.

Table 7. 7FA.05 version turbine model experience.

ReferencesAvailability & Reliability Source: ORAP®; all rights reserved: SPS®.



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©2009, General Electric Company. All rights reserved.

GEA17911 (10/2009)

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