Customer benefits

Up to 2.5% - 4% additional poweroutput delivered solely from theimproved compressor airfoil design

Additional power is permanentlyavailable, independent of ambientconditions

Optimized part-load operation

Well-proven design, no additionalsystems or power augmentationmeasures are required

No impact on hot gas pathcomponent lifetime

its improved compressor has provenits performance in several powerplants, and the C2 compressorupgrade package has been imple-mented in a number of plants world-wide. Alstom’s entire GT8C2 fleetand several upgraded plants areproving the success of thiscompressor.

The C2 compressor upgrade willincrease the power output of aGT8BC gas turbine by up to 2.5% and ofa GT8C, by up to 4%.

At the same time, its state-of-the-artblading design optimizes part-load oper-ation. No modifications are required tothe rotor, number of stages, or compres-sor casing, keeping the scope as narrowas possible to minimize the unit's down-time.

Technical ConceptThe C2 compressor upgrade increasesthe air and consequently, the gas massflow through the unit, increasing theengine’s power output at unchanged fir-ing temperature (TIT). No additionalthermal loading of hot gas parts occurs,and therefore there is no impact oncomponent lifetime.

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IntroductionIn 1999 Alstom’s brand-new C2 com-pressor was successfully installed in theGT8C engine at Martinlaakso, Finland.All expected performance values wereachieved and one year later in Birr,Switzerland, first firing occurred ofAlstom’s GT8C2 engine with the new C2compressor. Since then the turbine with

Increase your revenues by upgrading yourGT8BC or GT8C with the C2 compressor.

Improved Airfoil Design Higher Massflow Greater Power OutputImproved Airfoil Design Higher Massflow Greater Power Output

Gas Turbine - Performance Improvement

GT8BC/8C - C2 Compressor Upgrade

Extra Power for GT8BC and GT8C Gas Turbines

To improve plant performance and to stay competitive, existing gas turbine designs need to be periodically upgraded using state-of-the-art technology. Alstom’s well-proven C2 compressor upgrade package increases the power output of GT8BC gas turbinesby up to 2.5%, and of GT8C gas turbines by up to 4%, at unchanged turbine inlet temperature. This performance improvement isbased on a well-proven highly efficient compressor airfoil design that is optimized, stage-by-stage, for efficiency and pressureratio. The design of the C2 compressor allows additional power which is constantly available, independent of ambient conditions.The upgrade can be installed on-site, during a C-Inspection.

Higher performance results from astate-of-the-art, field-proven 12-stagecompressor airfoil design, and is achie-ved without sacrificing any of theunit's excellent reliability, availabilityand maintainability (RAM).

The latest 3-D numerical calculationtools were used to optimize the com-pressor front block, which is largelyresponsible for compressor mass flowand efficiency. Blades and vanes are ofstate-of-the-art Controlled DiffusionAirfoil (CDA) design, which replacesthe existing DCA (Double Circular Arc)profile.

This highly efficient blade design hasbeen adapted from the innovativecompressor developed for Alstom’sGT24/GT26 gas turbines. Extensivelyvalidated, this design is successfullyused in a large number of Alstom gasturbines worldwide, such as GT11N2engines, and the GT11NMC compres-sor upgrade.

2

NACA DCA CDANACA DCA CDA

NACA Profiles

(National Advisory Committee for

Aeronautics)

• Aerodnamic losses increase quickly

with the increase of incidence angle

• Design chosen from airfoil catalogue

• Not suitable for transonic conditions

Double Circular Arc Profiles

• Aerodnamic losses increase

moderately with the increase of

incidence angle

• Design chosen from airfoil catalogue

• Suitable for transonic conditions

Controlled Diffusion Airfoil Profiles

• Aerodynamic losses increase slowly

with the increase of incidence angle

• Specifically designed for existing

aerodynamic boundary conditions

• Suitable for transonic conditions

Evolution of airfoil design19801980 20052005

Three-dimensional computermodeling was used for aero-dynamic and mechanicalassessments

3

Scope of workThe upgrade package includes a com-pletely improved, field-proven 12-stagecompressor (blades, vanes, VIGV, andrequired assembly parts). There are norepeating stages; the design of eachstage has been aerodynamically opti-mized to maximize the compressor'sefficiency and pressure ratio.

The implementation of an additional3rd blow-off stage is included to opti-mize start-up behavior.

Alstom's OEM know-how has resultedin an upgrade package that requiresonly minor additional modifications,and can be implemented on-site withinthe framework of a regular C-Inspection.

For GT8B units, the C2 Compressorupgrade requires that the complete Cturbine is installed.

Piping for 3rd blow-off valve

Main Features

• 12 improved, field-provencompressor stages

• State-of-the-art ControlledDiffusion Airfoil (CDA) profiles

- Highly efficient airfoil designadapted from proven GT11N2and GT24/GT26 compressortechnology

- Replacement of existing DCAprofiles

• Each compressor stage optimizedfor efficiency and pressure ratio(no repetition stages)

• Use of latest aero technologies

• Additional blow-off valve forstart-up optimization

• Minimum unit downtime as modifications can be performedwithin the framework of a regularC-Inspection

Plant lifecycle

Perf

orm

ance

/ C

ompe

titiv

enes

s

New plant technology

Start of commercial operation

Maintenance

C2 Upgrade

Area of componentimprovements

Plant lifecycle

Perf

orm

ance

/ C

ompe

titiv

enes

s

New plant technology

Start of commercial operation

Maintenance

C2 Upgrade

Area of componentimprovements

Plant lifecycle

Perf

orm

ance

/ C

ompe

titiv

enes

s

New plant technology

Start of commercial operation

Maintenance

C2 Upgrade

Area of componentimprovements

Plant lifecycle

Perf

orm

ance

/ C

ompe

titiv

enes

s

New plant technology

Start of commercial operation

Maintenance

C2 Upgrade

Plant lifecycle

Perf

orm

ance

/ C

ompe

titiv

enes

s

New plant technology

Start of commercial operation

Maintenance

C2 Upgrade

Area of componentimprovements

New Plant technology is a key factor of success in staying competitive in a fast moving technology market.

Gas Turbine - Performance Improvement

Customer Benefits

• Up to 2.5% - 4% additional poweroutput delivered solely from theimproved compressor airfoil design

• Additional power is permanentlyavailable, independent of ambientconditions

• Optimized part-load operation

• Well-proven design, no additionalsystems or power augmentationmeasures are required

• No impact on hot gas path compo-nent lifetime

• Short installation time. Theupgrade can be performedduring a regular C-Inspection

• Reliability through proven technol-ogy, validation processes and anOEM's overall unit know-how

• Successful operation experience ona large number of Alstom gasturbines worldwide Units & GT Type Year of

C2

Fuel

Gas Dual Oil

Martinlaakso, Finland 8C 1999 X

Kladno, Czech Republic 8C 1999 X

Birr, Switzerland 8C2 2000 X

Baku 1, Azerbaijan 8C2 2000 X

Baku 2, Azerbaijan 8C2 2001 X

Hazira 1, India 8C2 2001 X

Hazira 2, India 8C2 2001 X

Salzburg, Austria 8C2 2002 X

Zuweitina 4, Libya 8BC 2004 X

Petkim, Turkey 8C2 2006 X

References at May 2008

Pow

er

Relative Efficiency100%

100%

105%

105%

C2 Upgrade

GT8

All values multiplicative

TIT unchanged

Pow

er

Relative Efficiency100%

100%

105%

105%

C2 Upgrade

GT8

All values multiplicative

TIT unchanged

Valid for GT8BC and GT8C configurations(ISO, Base Load, gas operation)

Expected C2 Compressor Performance Increase

Engine field experienceAlstom has extensive operational expe-rience with the C2 upgrade package.The first GT8C-C2 compressor upgradewas successfully implemented in 1999at Martinlaakso, Finland. All expectedperformance values were achieved,validating the new compressor design.

The package has since been implemen-ted in a number of GT8C and GT8BCplants worldwide. Alstom’s entire GT8C2fleet is also proving the success of thisupgrade.

PSE/BPROS/GCXPGT07/eng/PSER3/04.07/CH/6229 - © - ALSTOM 2008 - ALSTOM, the ALSTOM logo and any alternative ver-sion thereof are trademarks and service marks of ALSTOM. The other names mentioned, registered or not, are the property oftheir respective companies. The technical and other data contained in this document is provided for information only. ALSTOMreserves the right to revise or change this data at any time without further notice.

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