Gt24 and Gt26 Gas Turbines

GT24/GT26 SEQUENTIAL COMBUSTION

GAS TURBINES

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A WIdE PORTfOLIO fOR

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25percent of the world‘s

power production capacity depends on

Alstom technology

52,000 employees around the world in 70 countries

100years of industry leading expertise

With our recognised expertise all over the power generation market, we are able to find solutions to the challenges of today.

CLEAN POWER TODAY!™We recognise the need to improve the environmental balance of legacy plants while increasing adoption of new clean energy solutions.

Alstom is a global leader in power generation with a portfolio of products covering all fuel types. From fossil and biomass to nuclear and renewables, close to 25% of the world’s power production capacity depends on Alstom technology and services. Whether in design, manufacture, procurement or servicing, Alstom is setting the benchmark for innovative technologies that provide clean, efficient, flexible and integrated power solutions. Alstom can supply anything from single components to complete turnkey power plants. Our Plant Integrator™ approach and power automation and control solutions ensure the optimisation of all elements to derive the maximum lifetime value from all our customer’s investments.

Alstom has more than 100 years of experience in engineering, procurement and construction (EPC) of new power plants. But our engineers are also experts in retrofitting, modernising and servicing existing plants. With operations in 70 countries, Alstom is close to customers all over the world, ensuring rapid responses and service excellence at all times.

Welcome to Alstom

Alstom’s gas turbines stand out for their high overall efficiency, superior availability and enhanced flexibility

GT24/GT26 Gas turbines in a class of their ownThe GT24 and GT26 solutions represent an exceptionally successful approach to heavy-duty combined-cycle technology: many of their major components and subsystems have performed outstandingly for years in a number of applications, ranging from electrical power generation in base load, intermediate or peak duty, to industrial use such as in paper mills, district heating or desalination plants.

Utilities, independent power producers and merchant power generators have to face unprecedented change, from deregulation to tougher competition, shifting consumption trends and more stringent emissions legislation. They also need to ensure reliability of supply yet reduce the cost per kilowatt hour of producing electricity. Raising efficiency remains a constant challenge. Finally, flexibility to fuel gas composition must be included in times of global transport of fuel gas.

Alstom has addressed all of these challenges. The result is the compact GT24 (60 Hz) and GT26 (50 Hz) sequential combustion gas turbines, solutions that lower the kilowatt-hour cost combined with high availability by raising the efficiency in combined-cycle operation.

Environmental emissions are optimised thanks to Alstom’s unique, sequential combustion technology, which burns the fuel in two, dry low-NOx combustor stages. The GT24/GT26 can do all this with conventional firing temperatures and burners that are robust enough to cope with the wide fuel gas compositions now seen. What’s more, in addition to increasing their efficiency levels and power density, the operational flexibility of GT24/GT26 gas turbines is significantly improved and their turndown capability is unique, making them ideally suited to today’s markets.

Key benefitsCompetitive kilowatt hourIn combined-cycle applications, the GT24/GT26 is capable of producing high efficiency over a wide load range, using proven gas turbine technology.

High availabilityConventional turbine inlet temperatures, a uniform annular temperature profile, a maintenance-free, welded rotor and a simple and robust EV burner all help to reduce maintenance needs and therefore improve availability.

High power densityHigh power density designs lead to smaller components. Compared with Alstom’s medium-class gas turbines, the GT24/GT26 provides up to 60% more output for the same footprint.

GT24/GT26Right technology, right product

The highly efficient GT24/GT26: the result of extensive experience and evolutionary development.

Operational flexibilitySequential combustion means unrivalled operational flexibility, including the ability to handle wide fluctuations in gas compositions. With an operating range down to 20%, low-load operation and low NOx emissions, the plant can meet all power demands. And the GT24/GT26 is capable of switching online between performance-optimised and maintenance-cost-optimised modes.

Clean PowerSequential combustion technology is the industry‘s most innovative platform for clean power generation, resulting in gas turbines with low emissions and high efficiency.

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GT24/GT26Right technology, right product

Higher Performance, Cleaner Power

CLEAN POWER TODAY!®

The CHALLENGE Industry has always sought to develop a gas turbine with higher efficiency. The traditional solution is to raise the firing temperature at the turbine inlet.

This has drawbacks, however: it increases emissions into the atmosphere and subjects the entire gas turbine system to higher temperatures and thermal stresses.

The usual result is more frequent maintenance and reduced availability — defeating the initial objective. For decades conventional wisdom has decreed that efficiency cannot be increased in any other way.

The SOLuTIONThere is another way. By injecting fuel into two combustion systems in series, it is possible to increase output and cycle efficiency without significantly increasing the emissions at full and part load, since the firing temperature in the first combustor can be kept relatively low, and the second combustor does not make a substantial contribution to the level of engine NOx emissions. This is called sequential combustion.

For more than 50 years, Alstom has been a pioneer in sequential combustion technology. Over the years, we have made major system and component innovations, introduced incrementally, with successive gas turbine models. These include our industry-leading EV burners, annular combustion design and solid welded rotor. In so doing, we have succeeded in uncoupling emissions and efficiency through an inventive yet basic application of elementary thermodynamics.

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Sequential combustion can be visualised as a gas turbine comprising two combustor-turbines in series, where the exhaust gases from the first turbine feed the combustor of the second.

An efficient 22-stage subsonic compressor feeds combustion air into the first combustor. Fuel is mixed with the high-pressure air and burns in the first combustor — the annular eV combustor. The hot gases drive the single-stage high-pressure turbine.

Unlike conventional turbines, fuel is then injected into a second burner set and spontaneously ignites in the following annular combustion zone, the SeV (Sequential eV) combustor, thereby reheating the air and further expanding it through four low-pressure turbine stages.

The temperature of the eV combustor is maintained at a nearly constant level, resulting in lower NOx emissions – and cleaner power.

1st-stage EV combustorThe EV combustor has an annular burner arrangement. The GT24/GT26 gas turbines are fitted with retractable EV burners. Compared with other combustor arrangements, the annular combustor distributes the hot gas, circumferentially, at a much more uniform temperature.

Sequential combustion:Alternative approach, optimised design

Industry-leading burners

Vortexbreakdown

Sprayevaporation

Combustion air

LeanPremix Gas

RichPremix Gas

Premix Gas

Lean Premix Gasinjection holes

Ignition Flame front

Radial temperature uniformity is accomplished by pre-mixing compressor air with the fuel in the EV burner, and by the absence of film cooling in the convection-cooled combustor walls. This produces a single, uniform flame ring in the free space of the EV combustion zone.

A key benefit is that the flame has no contact with the walls of the burner. These design features distinguish the EV combustor significantly from other combustion systems.

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Like all the best ideas, sequential combustion is based on a simple concept: the reheat principle.

2nd-stage SEV combustorIn the annular SEV combustor, the combustion process is repeated as in the EV namely, vortex generation, fuel injection, pre-mixing and flame stabilisation in a vortex. The SEV combustor contains SEV burners distributed in a ring, followed by an annular combustion zone surrounded by convection-cooled walls.

Exhaust gas from the high-pressure turbine enters the SEV combustor through the diffuser area. Combustion temperature uniformity in the SEV, as in the EV, is achieved by the uniform premixing of fuel with air in a swirling flow with high mixing intensity. Each SEV burner contains four delta-shaped vortex generators on each burner wall in order to form four pairs of vortices in the combustion air.

Fuel is then injected through an air-cooled fuel lance, distributed with four jets into the vortex pairs such that it forms a perfect fuel/air mixture prior to combustion. The fuel jet is surrounded by cool carrier-air that delays spontaneous ignition until the fuel/air mixture has reached the combustion zone.Here, the mixture ignites spontaneously and, as in the EV combustion occurs in a single, stable flame ring, operating across its entire load range.

The EV and SEV do not require any parts replacement prior to HGPI (Hot Gas Path Inspection), C inspection. This mechanical simplicity determines the high reliability and availability of the GT24/GT26 design.

Sequential combustion:Alternative approach, optimised design

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High power density The sequential combustion concept results in a gas turbine with extremely high power density enabling the smaller blade dimensions of GT24/GT26 machines. The five rows of turbine blades are anchored in fir-tree slots.

Air from the compressor cools the high-pressure turbine stage and the first three low-pressure turbine stages utilising a combination of film- and convection-cooling techniques.

Maximised performance The cooling air for the hot gas path components is taken from four extraction points along the compressor. Air from two of these secondary airflows is used directly, while the two other streams are cooled by heat exchangers (once-through coolers) before entering the hot gas path components.

The heat rejected is recovered in the water-steam cycle, which maximises the performance of the GT24/GT26 in combined cycle applications. In simple cycle applications, the cooling is achieved by quenching water, which is introduced directly into the secondary air stream.

Its beauty lies

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Maintenance-free welded rotor

There is no need to destack and re-stack during the rotor lifetime.

Alstom’s welded rotor was first introduced in 1929 for steam turbines and the concept has been used successfully in Alstom gas and steam turbines ever since.

The welded rotor design eliminates maintenance work such as restacking and disk replacement during the service life of the rotor in any major overhaul of the gas turbine.

in its simplicity

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Performance

Although a large amount of the total unit fuel is burned in the SEV combustor, very little additional NOx (at 15% O2) is formed in the SEV combustor, mainly due to the low oxygen content of the incoming air.

At full load, approximately half of the total amount of fuel is burnt in the first-stage EV combustor. Initial expansion occurs in the single-stage high-pressure turbine (HPT). The high-pressure turbine exhaust gas enters entirely into the second combustor. The remaining fuel is introduced and burnt in the second ‘reheat’ combustor (the SEV combustor).

Efficiency only equaled by its reliability

The second expansion occurs in a four-stage low-pressure turbine (LPT). At over 600°C, the exhaust gas temperatures are ideal for combined cycle applications.

The GT24/GT26 achieves low NOx emission levels, not only at full load, but also down to low-part loads. This is due to the operation concept that maintains the EV combustor temperature at a nearly constant level. Furthermore, the SEV combustor produces only little additional NOx.

The EV/SEV burners also enable dry low NOx combustion with different grades of natural gases, and the use of liquid fuel as back-up.

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with unique track record

Alstom is the pioneer of operational flexibility. We are the pioneer in introducing the ‘low load concept’, which means that the plant can be parked at 20% load during periods of low demand during part-load operation. Efficiency of our plant stays virtually constant from 100% down to 80% load and even at the lowest load, emissions stay within statutory limits.

The proven output and efficiency are being offered from an existing and well-proven technology platform. This gas turbine technology has over 15 years operating experience with more than 4.5 million operating hours.

The GT24/GT26 gas turbine is still the only advanced-class turbine with sequential combustion and proven technology to deliver:· Low Cost of Electricity· High All-round Efficiency· Exceptional Operational Flexibility

Performance and operational flexibility, with a unique track record

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Powertrain arrangementsAlstom has extensive experience with both single- and multi-shaft powertrain arrangements, in all types of operating regimes from base load to daily start & stop.

[1] STEAM TURBINEAlstom steam turbines offer:•HPturbineshrink-ringdesignforsustainedefficiencyand

fast start-up welded rotor design for fast start-up and low maintenance

•single-bearingdesignforcompactarrangement•singleaxialandlateral-exhaustdesignsalsoavailableforlower

foundations and lower first costs.

[2] TURBOGENERATORAlstom turbogenerators demonstrate high efficiency, reliability and availability with low maintenance requirements. According to plant size and arrangement, both air-cooled TOPAIR and hydrogen-cooled TOPGAS generators are available.

[3] GAS TURBINEAlstom gas turbines - the core of any combined cycle plant.

[4] HEAT RECOvERy STEAM GENERATOR (HRSG)Alstom’s range of HrSGs provides:•bothdrumtypeandonce-throughtechnology•optimisedcold-end.Performance for maximised combined-cycle efficiency•highthermalflexibilityforfaststart-up•highlymodulariseddesignforfastsiteerection.

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The Alstom Powertrain

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How it works

[1] COMPRESSEd AIR is fed into the EV burner, creating a homogeneous, lean fuel/air mixture. The vortex flow, induced by the shape of the burner, breaks down at the EV burner exit into the combustion zone, forming a central recirculation zone.

[2] THE MIxTURE ignites to form a single, low-tempera-ture flame ring. The inner recirculation zone stabilises the flame in the free space within the combustion zone, avoiding contact with the burner wall.

[3] THE HOT ExHAUST GAS,low in oxygen content, exits the first combustor and moves through the high-pressure turbine stage before entering the SEV burner.

[4] vORTEx GENERATORSin the SEV burner enhance the mixing process, while carrier air, injected with the fuel at the SEV fuel lance, delays spontaneous ignition until the mixture enters the annular SEV combustion chamber.

[5] IGNITION OCCURSwhen the fuel reaches self-ignition temperature in the free space of the SEV combustor. The hot gas then con-tinues its path into the low-pressure turbine.

1 2 5

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Optimised designAlternative approach, additional advantages

The Alstom

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Sequential combustion applicationsCOmbINed-CyCLeA combined-cycle power plant is an efficient and environmentally sound way to generate electrical power. Sequential combustion provides optimum exhaust temperatures for combined-cycle use, the main application for which the GT24 and GT26 have been developed.

The two combustors in the GT24/GT26 sustain high efficiency and low emissions at part load operation through control of the inlet air flow by four rows of variable guide vanes.

This means the thermodynamic quality of the sequential combustion combined-cycle remains nearly constant. As a result, the GT24/GT26 combined-cycle offers high efficiency over the operational load range, with virtually constant efficiency between 100% and 80% CCPP load.

This maximises the long-term value of GT24/GT26 power plants by significantly broadening their operating flexibility — a key success factor for today’s competitive power generation market.

Langage combined-cycle power plant in Devon, uK.

rePOwerING wITH SeqUeNTIAL COmbUSTION GAS TUrbINeSAlstom has developed a hybrid plant concept combining conventional steam plants with the GT24/GT26. These plants combine operating and dispatching flexibility with continuous fuel optimisation, low O&M costs and moderate capital investment.

The concept responds to the most critical requirements of modern power generation systems — low generating costs, greater fuel mix capabilities, operational flexibility and minimum environmental impact. It also enables extraordinary design flexibility by integrating high-performance sequential-combustion gas-turbine technology with a wide range of existing or new conventional steam power plants.

Innovative concepts

100

CCPP

Rel

ativ

e

Typical MSL

2%-4%

90 80 70 60 50 40

KA26

Single Combustor GT

Superior part-load efficiency characteristic of the KA24/KA26 CCPP. One distinct feature is the fact that the plant efficiency stays nearly constant from 100% down to 80% combined cycle, a unique capability in the market.

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Innovative concepts that also lower costs

Gas turbines in action - project highlights

A GT26 merchant power plant applicationScottish Power Ltd selected the KA26-1 standard single-shaft design to build a combined-cycle power plant at Shoreham Harbour in the United Kingdom. The plant was completed in december 2000 and is managed on a merchant plant basis. It has operated at both base load and intermediate duties.

The first GT26 single-shaft power plantContact Energy in New Zealand is the owner of an Alstom turnkey 360 MW combined-cycle power plant, featuring the GT26 sequential combustion gas turbine.

Taranaki is arranged in a single-shaft configuration and represents the first standardised reference plant solution with the GT26. This triple-pressure reheat combined-cycle plant has been in continuous base load operation since July 1998.

SHOREHAM / uK

TARANAKI / NEW ZEALAND

A GT26 fast-track project in SpainThe Cartagena project, a 1200 MW combined-cycle power plant consisting of three independent blocks equipped with dual-fuel GT26 gas turbines, was awarded to Alstom in december 2003 with a very aggressive timetable.

The first unit was finished within 25 months, with the other units following at one month intervals. This is a repeat order for Gas Natural, which already owns and operates two other GT26 combined-cycle power plants in Spain.

efficiency increase by 20%Alstom won a contract with Spain’s ACS Group to provide power equipment and services for the El Sauz combined cycle power plant in Queretaro, one of Mexico’s most industrialized states.

A new GT24 gas turbine to replace the existing gas turbines and will retrofit the steam turbine at the existing El Sauz gas-fired power plant, which has been operating since 1981. This new contract will add 25 years to El Sauz combined cycle power plant and boost its efficiency by 20%.

CARTAGENA / SPAIN

EL SAuZ / MEXICO

A GT24 in cogeneration applicationIsland Cogen is a 250 MW gas-fired combined-cycle cogeneration power plant at Campbell River in British Columbia, Canada. The plant is owned by Calpine and delivers steam to an adjacent paper mill.

Superior reliability & availabilityRoad generating plant in dayville, Connecticut, U.S.A. Lake Road is a 792 MW combined-cycle generating facility based on three GT24 gas turbines.

The units have exhibited good starting reliability and high availabilities during operation. The Lake Road combined-cycle generating facility features dual fuel flexibility that utilizes natural gas as the primary combustion source and distillate fuel oil as a backup. The plant entered commercial operations in May 2002.

ISLAND COGEN / CANADA

LAKE ROAD / uSA

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The Alstom Power Plant

Partnership throughout

In today’s power generation and industrial markets, plant owners and operators seek to establish long-term cooperation with major Original Equipment Manufacturers. They look for partners who are willing and able to develop solutions that will increase production efficiency and reduce emissions throughout the lifetime of their equipment.

As part of Alstom’s commitment to providing complete plant services for optimal performance, we are dedicated to supporting you to cost-effectively maintain your gas turbine and combined-cycle (GT/CC) power plants.

Our flexible and customised expert services cover solutions at all stages of the plant lifecycle or if requested simply on single components including:

• Newandimprovedparts• ReconditioningServices• Adviceandoperationalsupport• Fieldservice• Performanceimprovements• Servicecontracts• ServicesonotherOEMgasturbines

In-depth service portfolio combined with broad experience

Located in Birr, Switzerland, the Alstom Power Plant provides a unique environment for maintaining the incomparable advantages of the GT24/GT26 range, all within the proximity of Alstom’s R&D facility, gas turbine development department, manufacturing plant and power plant. The latter is equipped with a dual-fuel GT26 gas turbine, operating in simple-cycle mode, connected directly to the 220 kV Swiss power grid.

As it is an Alstom facility, the turbines can be submitted to a real-life comprehensive validation process that leaves nothing out in terms of loads, limits or duration. The GT26 is operated under real service conditions without any commercial constraints. This includes fuel switch-over operation between gas and oil. The power plant has oil storage sufficient to run the GT26 for 12 hours at full-load.

Together with the Product Support organisation and the GT development department, the Power Plant means Alstom can ensure seamless implementation of evolutionary product improvements based on actual GT24/GT26 fleet experience.

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AmerICAS danville Richmond Richmond Richmond Jupiter Jupiter Jupiter Sao Paulo

eUrOPe Baden Baden Baden Ashby Birr Karlovac

mIddLe eAST / ASIA PACIFIC dubai dubai dubai Rabigh Kuala Lumpur Kuala Lumpur

Reconditioning Workshop Execution Centre Product Centre Field Service Network

We are where our customers are

Partnership throughoutthe plant’s lifecycle

Alstom’s footprint and broad industry expertise enables us to support you in an efficient and responsive manner around the world. With a network of over 60 Local Service Centres in 70 countries, there is always a dedicated Service manager close at hand and available around the clock to respond to your needs.

• 2GT/CCproductcentres• 4GT/CCexecutioncentres• 7GTreconditioningworkshops• 7fieldservicenetwork

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Services

Service ContractsAlstom’s service contracts are tailored to meet all your operational, maintenance and support requirements. whether you prefer a Long Term Agreement (LTA) or an Operation & maintenance (O&m) contract with Alstom’s comprehensive, yet flexible agreements, you can be sure of a win-win situation.

Partnerships for performanceLong-term agreements are based on framework contracts that define prices and conditions in advance. Besides offering preferential conditions for high quality parts and services, the LTA reduces administrative efforts and simplifies planning. The scope of services and equipment covered, as well as the contract duration and risk sharing, can be adapted perfectly to your needs.

LTAs offer many immediate advantages:• Fixedpreferentialpricesforpartsandservices• Flexiblescopetosuitoperativestrategy• Extendablescopetoincludealmostanyaspectofplantoperations Alstom’s operation and maintenance contracts let plant owners devise completely new management strategies by outsourcing risks and responsibilities. Take advantage of performance and availability guarantees through tailored agreements that perfectly suit your required service and equipment scope.

Alstom’s O&M contracts are fee-based agreements that:• Mitigaterisks• LeverageAlstom’sextensiveexperienceinplantassetmanagement• Canbeadaptedtosuityourbusinessstrategy

Plant Support CentreTM

expert support around-the-clockAlstom’s Plant Support Center™ (PSC) offers fast and comprehensive technical support solutions to keep plants competitive. Besides remote monitoring and diagnostic services, the PSC provides 24/7 operation support and direct access to a global network of technical experts who assist in troubleshooting, assessment and re-commissioning and analyse equipment trends.

Besides practical experience, our plant operation experts rely on comprehensive and proprietary knowledge management tools. If required, they can also call in Alstom experts with specific engineering know-how and fleet-wide experience to assist with operational support or more detailed investigations.

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Alstom contributes to the protection of the environment.This brochure is printed on environmentally-friendly paper.

Alstom (Switzerland) LtdBrown Boveri Strasse 7CH-5401 BadenPhone: +41 56 205 6923

www.alstom.com/power