FUEL FLEXIBILITY AND GAS TURBINE TECHNOLOGY … · FUEL FLEXIBILITY AND GAS TURBINE TECHNOLOGY (Externalities of fuel gas composition) Jonathan Lloyd Director of Marketing & Strategy

“XVII International Gas Convention” (AVPG) May 2006 1

FUEL FLEXIBILITY AND GAS TURBINE TECHNOLOGY

(Externalities of fuel gas composition)

Jonathan Lloyd Director of Marketing & Strategy ALSTOM

J.Fredrik Bok Executive Sales Manager (Mexico, Venezuela, C.A. & Caribbean)

ALSTOM


FUEL FLEXIBILITY AND GAS TURBINE TECHNOLOGY

The focus of this paper is on the fuel flexibility of gas turbine technology and the economical value these capabilities have in a fast changing and demanding power generation environment. The paper will also explore the current state of the fleet engines as installed in gas turbine power plants in the Latin America power generation markets. Today’s power and energy markets are paying great attention to lowering environmental impact during transmission constraints when capturing the value of cross-state energy swaps, hourly and seasonal market arbitrage, peak shaving, and ancillary services. Consequently plant with high operation flexibility is able to provide a high economic value to both to public and private utilities, as well as to industrial electricity consumers. Until relatively recently, gas quality differences have not been given a high priority. Some publications addresses the fact that few Latin American countries are about to become dependent on high volumes of imported gas but does not consider gas quality issue in detail. It is also noted that quality of the natural gas including LNG supply has changed, more specifically, heavy hydrocarbon liquids are now commonly found in the gas supply delivered to power plants. This requires gas turbines with the correct level of technology to be able to successfully burn gases with these compositions. Also variations in the heating value as a result of gas phase composition variation affect gas turbine emissions, output and combustion. The power plant shall have gas turbines which need to vary their operation regime over time from an intermediate plant to base load operation depending on the power demand of the industry and the dispatch criteria from the Grid. Other benefits stem from the commendable load following capability of the gas turbine unit, especially relevant under today’s hostile and insecure power market conditions. The development of gas turbine technology is still moving rapidly towards higher operational flexibility and reduced cost of electricity. In parallel reliability, availability and maintainability are strong requirements from all power generators. In the mean time regional integration in power and gas markets are maturing slowly and as such the power plants must follow the economical trend of those changes without implementing new major changes in the process. Our large gas turbine basic design is clearly responding to these operational benefits, to sustain performance, even in a volatile power environment. In this paper we will show how our company is responding to this challenge.


TABLE OF CONTENT

1 INTRODUCTION

2 POWER GENERATION ENVIRONMENT

2.1 A volatile power generation environment........................................................

2.2 Fuel gas quality and infrastructure development ............................................

3 EXTERNALITIES OF FUEL COMPOSITION

3.1 The impact of changing gas composition on the GT24/GT26.........................

3.2 Sequential combustion of the GT24/GT26......................................................

3.3 Development of design improvements ...........................................................

3.4 Implementation range of acceptable fuel gases .............................................


1 INTRODUCTION

Worldwide natural gas consumption – which fifty years ago stood at about ten percent of overall energy use – will continue to rise through 2020, as gas captures about one-third of all incremental energy growth. By the year two thousand and twenty, gas will supply about a quarter of global energy demand. Fortunately, worldwide gas supplies exist to meet its share of the expected demand. However, to realize those benefits, new gas supplies will be needed to satisfy growing world demand and to replace declines in existing production. Furthermore gas must be transported in liquefied form to satisfy the global market requirements – this imposes a wider range of gas compositions. Gas turbine technology must continuously develop in parallel to be compatible with inter-changeability of gas supplies while maintaining reliable and environmentally friendly power generation

2 POWER GENERATION ENVIRONMENT

2.1 A volatile power generation environment

The first part of this paper will outline the current volatile situation in the power generation environment. Focusing on gas supply, you will see how the further development of the LNG market in Latin America is planned and you will see the potential impact on future fuel specifications and inter-changeability requirements. The second part of this paper will introduce our company’s state-of-the-art gas turbine and highlight the advantages of the sequential combustion technology in today’s market environment. Also the experience this engine has accumulated in operation with non-standard fuels with low emissions and at high part-load efficiency. To elaborate on this experience, the paper describes the validation concept including a description of the full-scale test facility in our company’s gas turbine test centre in Switzerland. All our gas turbines are fitted with environmental burners, which are characterized by their simplicity and robustness and as such are less sensitive to gas quality and cleanliness issues that affect the gas turbine operation. These environmental burners demonstrating very low emission levels, has accumulated more than 4.5 million operating hours across all of the gas turbine range. Also our large gas turbines for respectively the 60Hz and 50Hz market are the only ones in the world that is using sequential combustion system.


ALSTOM (Switzerland)Ltd© 2005 Preliminary/for discussion purposes only. We reserve all rights in this document and in the information contained therein.Reproduction, use or disclosure to third parties without express authority is strictly forbidden. 3

AVPG ConferenceMay, 2006

Latin American Energy MarketA Volatile Power Environment

Gas supply restrictionsLow service factorPart load operation

Transmission gridDispatch restrictionsPart load operationEmissions

requirements (by PPA’s)

Cooling regulationSeawater discharge

Gulf-Pacific

Coastal Industrial &Desert areas

Closed MarketPublic Utility

Monopoly-PPAFuel gas pricing

Fuel gas imports

Cross-Border Regulations

GT24/GT26

Operational Flexibility

EmissionsPart-load

Figure 1 – Volatile power environment

There are a lot of factors in volatile power environments - which needs to be taken into account. Things such as gas supply congestions, transmission grid bottlenecks can lead to an economic advantage of stable and highly efficient part load operation, favouring those plants with better part load behaviour. Also water shortage requires intelligent Full-Service Provider solutions, like the use of municipal waste water or sea water for cooling.

2.2 Fuel gas quality and infrastructure development

During the last years many advanced-technology gas turbines of the “F” class type has been installed mostly in Mexico, the majority at the north and northeast areas and along the gulf coast. The local available gas is basically coming from the south and the north plus short term imported gas from various locations across the US borders. With the proven gas reserve in Latin America the hemispheric LNG integration is already a reality, by the year 2007 the first marine terminal for LNG supply at ALTAMIRA in the gulf coast area should come into operation The current installed IPP combined cycle power plant capacity in Mexico is 11.5 GW. A further 12 GW-CC is planned by 2014. Equally new capacity for the power sector in Venezuela is estimated 3.0 GW.




POTENTIAL LNG IMPORTS from: • East: Algeria, Nigeria• West: Indonesia, Australia, Russia• North: Imported pipeline gas• South: Peru, Bolivia, Trinidad, Venezuela

• Fuel gas consumption is expected toIncrease by factor 2.5 btw.2004-12

MexicoGas Import Infrastructure Development

BAJA REGION(2008) 1.75-2.4 BCFD

Imports

ImportsImports

Imports

GULF OF MEXICO

ALTAMIRA(2006- under construction)0.5 – 1.3 BCFD

SONORA(2008) Peak 1.3 BCFD

LAZARO CARDENAS(2008) 0.5 BCFDMANZANILLO

(2008) 0.5 BCFD

• IPP installed CCPPby 2004 -11.5 GW

• IPP planned CCPP+18 GW by 2012

TOPOLOBAMBO

Figure 2 – Gas import infrastructure

Fuel gas consumption is expected to increase by a factor of 2.5 between 2004 and 2012 in order to supply gas for increasing power demands. This increase will only be possible by increasing production internally and/or by building the infrastructure to import by means of LNG With the maturity of planning for the LNG import infrastructure comes the reality that, gas may be imported from such vast global destinations as: Algeria and Nigeria in the east Indonesia, Australia, and Russia in the west, imported pipeline gas from the north, also blended from various sources and LNG from Peru, Bolivia, Trinidad & Venezuela from the south. Strategic gas development plans in Venezuela emphasizes the Latin American and Caribbean integration where gas production today is around 6’300 MMCFD and by 2012 the gas production would be 11’500 MMCFD. Regional Integration of the Americas gas markets (existing & future) will drive successfully the energy development when competing for supply globally and not regionally.


3 EXTERNALITIES OF FUEL COMPOSITION

For operational flexibility in power plants new parameters are needed. Traditionally, the major focus has been on first cost $US/kW, not operating cost $US/kWh, of industrial gas turbines. Experience with advanced technology such as the GT24/GT26, however, reveals that a low first cost does not mean a lower total cost during the expected life of the equipment. Conversely, reliable and high quality equipment with demonstrated flexibility will be remembered long after the emotional distress associated with high initial cost is forgotten.

3.1 The impact of changing gas composition on the GT24/GT26

How can gas demand, supply and inter-changeability be managed while maintaining reliable power? This analysis leads to the important and very relevant question for this conference and for this audience. First, let‘s get back to basics and define the parameters that are most relevant to inter-changeability – heating value (or Btu content) and WOBBE Index Inter-changeability is defined as the ability to;



Back to the BasicsWhat Influences Interchangeability?

Defining ParametersHeating Value: The net energy released during oxidation of a unit of fuel

– Lower Heating Value (compared to Higher Heating Value) excludes the heat required for vaporization of the water from combustion

Wobbe Index: Classification of interchangeability for a burner of fixed geometry at constant pressure

– Dependent on definition!!

– Not easy to translate without information on the fuel composition

21

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⎟⎟⎠

⎞⎜⎜⎝

⎛=

air

gas

gasmassLHVIW

ρρ

ρ

SGHHVIW vol=..

nditionsStandardcoair

gasSGρρ

=

ALSTOM GAS SUPPLY SPECIFICATIONS

INTERCHANGEABILITY:The ability to substitute gaseous fuels in a combustor without requiring major hardware

changes while maintaining similar performance

Figure 3 – Back to Basics


• The heating value refers to the net energy released during combustion of a

unit of fuel. Heating value is expressed in terms of Lower Heating Value, also known as Net Calorific Value, or Higher Heating Value, also known as Gross Calorific Value. The difference between the two values is that the lower heating value excludes the heat required for vaporization of the water from combustion

• The WOBBE Index provides a classification for the inter-changeability for a burner of fixed geometry at constant pressure; injectors with the same WOBBE Index have the same pressure drop for a given thermal power

• The WOBBE Index is not a dimensionless number therefore be careful – it is dependent on definition….GT Original Equipment Manufacturer’s typically define WOBBE Index on the basis of the lower heating value

Most gas supply specifications speak a similar, but different language…WOBBE Index is typically defined by the volumetric higher heating value and specific gravity defined at standard conditions. In order to convert the gas supply specification to terms applicable to gas turbine operation, knowledge of the full gas composition is required. As we will see shortly, high hydrocarbon content and inert content have an impact on combustion behaviour.



Fuel composition varies depending mainly on content of methane, higher hydrocarbons (C2+) and inerts (nitrogen, carbon dioxide)

Both the overall range in gas supply and allowable fluctuations are important

The U.S. situation is particularly critical because gas systems are tuned to gases with ethane and propane removed – imported LNG has higher C2+ content

Back to the BasicsWhat Influences Interchangeability?

INTERCHANGEABILITY: European and North American studies show that the range in gas specs allowable

for pipeline regulations and appliances are tighter than ALSTOM range.

Defining parameters Fuel Composition FormulaMethane [%-mol]C2+ [%-mol]Inerts [%-mol]Higher Heat Value [MJ/kg]Lower Heat Value [MJ/kg]Density [kg/m3] Wobbe Index [MJ/m3]

Gas A100

00

55.650.00.6845.5

Gas B82.7915.581.63

52.547.50.8349.3

Gas C72.3710.1917.44

36.933.30.9637.2

Figure 4 – Influences interchangeability


Fuels with high hydrocarbon content or high inert content influence the heating value ad WOBBE Index of the fuel C2+ refers to all hydrocarbons beyond CH4 – Methane Inerts refer to substances such as Co2 or N2, naturally present in gas Several representative examples are shown:

1.) 100% methane for comparison (Methane has the highest LHV) 2.) A high C2+ gas 3.) A High c2+ and high inert gas

Gas B and Gas C represent gases, which are already fueling a GT24 and GT26 Publicly available studies show that European and North American range in inter-changeability parameters for pipeline regulations and appliances are tighter than the ALSTOM fuel specification.


Latin America Energy ConferenceMay 16, 2005

Reactivity– flashback– ignition– flammability limits– emissions

Volumetric air/fuel ratio– injector design– fuel-air mixing– combustion stability

fuel quality & specification

Gas

pre

ssur

e

LHV

CO

C2+

INER

TS

High Hydrocarbons“C2+”

Ethane C2H6Propane C3H8Butane C4H10C5, C6, ..

“Inerts” Nitrogen-N2Carbon Dioxide-CO2

Wob

be in

dex

H2

Back to the BasicsImpact of Gas Composition on Combustion

Figure 5 – Impact of gas composition

To highlight the effect of gas composition on combustion, we classify fuels by C2+ content and inert content. The High Hydrocarbons, or high C2+, covering component with 2 or more carbon atoms, has an influence on the reactivity of the fuel - Challenges such as flashback or emissions must be solved. The other group are the “inerts”, i.e. fuel gas contains high content of nitrogen or carbon dioxide. These non-flammable gases lower the heating value and increase the volumetric flow; this may influence or cause negative affects on the combustion stability as well as the low NOx characteristics of the engine. Our combustion engineers have mastered both of these challenges already for some time.


With an understanding of the impact of gas composition on combustion and an understanding of inter-changeability parameters, let‘s take a look at our company’s broad experience range relative to typical LNG specifications and recent fuel specifications in current projects.



Natural Gas SpecificationsCompany’s Broad Experience Range

24

28

32

36

40

44

48

52

0 2 4 6 8 10 12 14 16 18

Low

er H

eatin

g Va

lue

[MJ/

kg]

ALSTOM GT26 Test CenterFuel Specification RangeProject #1

Field Engines with Standard Fuel Gas Example LNG Composition

Field Engines with Non-Std Fuel Gas

High Hydrocarbons “C2+” [Mol %]

Fuel Specification RangeProject #2

Figure 6 – Natural gas specifications

Blue diamonds show examples of LNG compositions collected from a number of exporting countries including:

• The squares represent the range in fuel specification for 2 specific projects and a collection of recent projects

• The brown squares show an Asian project in a region where C2+ and high inert fuels are common

• The red squares show a project where gas supply is uncertain, but LNG is likely therefore a wide range in composition results

• The yellow squares represent six different projects with more standard specification.

• The white triangles show a sampling of the range of gas compositions tested at the ALSTOM Gas Turbine Test Centre.

• The bright blue circles represent field engines operating with standard fuel gas


• The light blue circles represent the range of field engines operating with

non-standard fuel gas–both high C2+ gas and high C2+ gas with high inerts.

The range of gas composition in recent projects exemplifies the uncertainty of supply for certain projects as well as the range of possible gas compositions around the world. The experience range of our company combined with the testing range proves that the GT24/GT26 with the sequential combustion technology provides a significant advantage for the current situation in the market.

3.2 Sequential combustion of the GT24/GT26

Introducing in more detail to the sequential combustion technology – what is it and what are the advantages and also validation concept followed for GT24/GT26 product improvements using fuel flexibility as an example of how this concept has been successfully used. The history of burner development, and Sequential combustion is shown over time. The diffusion burner was integrated in our first sequential combustion system in 1978 at the “Huntorf” PP in Germany. The facility consist of a single shaft power plant with an output of 225 MW and an efficiency of 33%.



GT24/GT26 ArchitectureSequential Combustion History

19931939Time

ALS

TOM

Pow

er

GT-

Tech

nolo

gy

1978 1984 1991 1992

HUNTORFSequential Combustion

DiffusionBurner

Premix BurnerBlue Flame

Silocombustor

Singleannular

combustor

SequentialCombustion

Integration of 2 known concepts

EV Burnerin AnnularCombustor

GT24/GT26Sequential

Combustion

Figure 7 – Sequential combustion history


The history went from Silo type sequential combustion with diffusion flame to sequential combustion with environmental (EV) burners in annular combustor. The premix flame burns with a lean mixture of fuel pre-mixed upstream of the primary combustion zone – the advantage of this technology – recognized by the blue flame is a lower flame temperature and therefore significantly lower NOx emissions. Our largest gas turbines use a sequential combustion system, which makes use of the thermodynamic “reheat” principle. The single shaft sequential combustion turbine (GT24 for the 60 Hz market and GT26 for the 50 Hz market) incorporates two combustors, which operate simultaneously and sequentially. This process enables higher thermal efficiencies with lower temperatures and emissions to be achieved, while still relying on well-proven components and technologies.



GT24/GT26 ArchitectureSequential Combustion

Annular EV Combustor

EV = EnVironmentalSEV = Sequential EnVironmental

High PressureTurbine

Compressor

Annular SEV Combustor

- EV combustor EV burner

Low PressureTurbine

LP TurbineHP Turbine

Compressor

SEVcombustor

Figure 8 – Sequential combustion

Brief explanation of the GT24/GT26 heavy-duty gas turbine. After leaving the compressor, the air enters the first combustor, the EV combustor where fuel is injected through the EV burners. The hot exhaust gases exit the combustor, expand through the single stage HP turbine and then enter the SEV burners where additional fuel is injected. Spontaneous ignition occurs in free space of the SEV combustor and the hot gases then expand through the 4 stages LP turbine.


Control of the system is fully automated – for the operator the plant is controlled by a “push of a button”. Sequential combustion principle achieves high efficiencies without corresponding high increases in turbine inlet temperatures. In addition no burner outages between Hot Gas Path inspections at 24’000 EOH are required, and no burner tuning is necessary.



Gas

Gasinjection

Vortexbreakdown

Swirler

Gas injection

Burner exit plane

Combustionair

Premixing(Gas Combustion air)

Flame front

Vortex breakdown

EV-BurnerPremix Combustion

GT24/GT26 ArchitectureEnvironmental (EV) Burner

Dual fuel, flexible, low emission burner:– Simple, robust design (2 pieces)

Dry low NOx, premix operation:– Fuel gas injection into vortex– Flame stabilized in vortex break-

down

Figure 9 – Environmental (EV) burner

If we look a little bit more in detail at the EV burner, which is used in all of our engines from the GT8C2 (56MW) through to the GT26 (280 GT-MW). It basically consists of a split cone; the air entering the slots and mixing with the fuel gas which is injected through a row of holes along the sides of the slots. A homogeneous lean air/fuel mix is created. The vortex flow, induced by the shape of the burner breaks down at the EV burner exit. The mixture ignites into a single low temperature flame ring, with the diffusion flame stabilizing in free space within the combustor, with no contact with the burner or combustor walls. The SEV burner makes use of the same principle: vortex generation, fuel injection, premixing and vortex breakdown with the flame stabilising in the SEV combustor, again without contact with the combustor walls.


This combustion system leads to low emissions, with typical operating figures at full load of around 10 - 15ppm without using a catalyst.

3.3 Development of design improvements

Until now we have shown and explained our company’s competitive technology, but how did we get there? Development of design improvements takes place in three main phases: design, validation and finally implementation. In the design phase, product improvements are based on both accumulated operating experience and qualified technology. In the validation phase a specific validation path is determined depending on the level of the change to the basic design. Validation may occur at the level of design feature testing. An example as shown here is liquid crystal testing for film cooling effectiveness of turbine vane designs



DESIGN

VALIDATION

IMPLEMENTATION

Company’s Validation ConceptDevelopment of Design Improvements

Design ImprovementDesign Improvement

Qualified Qualified TechnologyTechnology

Operating Operating ExperienceExperience

Fleet ImplementationFleet ImplementationFleet Implementation• Reconfirm measurements with

reduced instrumentation scope• Continuous fleet feedback

Validation path determined by level of change to basic design

Design Feature Testing

Design Feature Design Feature TestingTesting

Film Cooling

Liquid Crystal

Component Testing

Component Component TestingTesting

EV Liner Vibration Rig

Engine Testing (Birr Test Center)Engine Testing Engine Testing

(Birr Test Center)(Birr Test Center)

Engine Testing

Figure 10 – Validation concept

The second level of validation occurs at the component level. This may be a compressor rig test, or as shown here, a vibration rig to test the integrity of the EV combustion liner. Finally, engine testing is used to confirm the integrated engine design and operability. The GT24/GT26 engine testing is based in Birr Switzerland at the company’s Gas Turbine Test Centre. In the final phase, the design improvement is implemented into the fleet and measurements are reconfirmed


with a reduced instrumentation scope. Continuous feedback is gathered from the fleet in order to continuously develop and implement product improvements. The Company’s Gas Turbine Test Centre is home to both a GT26 and a GT8C2 test engine. First firing of the GT26 took place ten years ago in 1996. The test facility is equipped to run a dual fuel gas turbine in simple cycle operation mode with dispatch to the Swiss national grid at all load conditions. Extensive testing campaigns have been demonstrated to the Test centre, including thermal paint testing, air inlet cooling validation and combustion optimization. The Company’s Gas Turbine Test Centre is a clear advantage in the validation of our product improvements. First, we have flexibility in test campaign planning without commercial time constraints imposed in the case of a commercial site fleet leader



Gas Turbine Test CenterBenefits

Flexibility in test campaign planning; without commercial time constraints

Ability to operate the engine outside normal limits

Rainbow tests for design optimization

Proximity to R&D and manufacturing facilities

Operating experience under real load conditions (connection to Swiss grid)

Gas Turbine Test Center and Rotor/Blade Manufacturing in Birr (CH)

The ALSTOM Gas Turbine Test Center Advantage

Figure 11 – Gas turbine test centre benefits

We use the test engine to operate the engine outside of normal limits – for example, the GT26 compressor upgrade test campaign included surge approach


tests. Rainbow tests are used to optimize designs. Rainbow tests refer to testing of multiple design alternatives in one engine run. The Test Centre in Birr is located only 12 km from the R&D headquarters for gas turbines in Baden, Switzerland. Finally operating experience is accumulated under real load conditions actually dispatching 260MW to the local grid



Gas Turbine Test CenterFuel Mixing Plant

Full load steady state operation with natural gas and oil fuelFuel switch-over testsTests of gases with high hydrocarbons (C2+) and/or inerts (CO2, N2)

Fuel mixing plant at the GT Test Center in Birr, CH

ALSTOM has built an extensive and unique designexperience for high inert and high C2+ gases

Nitrogen Tanks and PumpMixing StationPropane Pump

Figure 12 – Gas turbine test centre fuel mixing plant

ALSTOM has built and extensive and unique design experience for both high inert and high C2+ gases. Within the Test Centre, a fuel mixing plant has been constructed to mix fuels with compositions representative of market requirements

3.4 Implementation range of acceptable fuel gases

As a result from extensive engine testing, the range of acceptable fuels was verified. Looking first at Lower Heating Values, the standard fuel gas range is between values of 35 and 50 MJ/kg.


With an increasing inert content, there is a decrease in the LHV. For fuel gases which are significantly below a LHV<35 MJ/kg the burner design still remains the same. However it may be necessary to adjust the injections hole pattern on the EV burners to ensure the full burner performance and avoid combustion instability. No adjustments to the SEV burners are required.



24

28

32

36

40

44

48

52

0% 2% 4% 6% 8% 10% 12% 14% 16% 18%

High Hydrocarbons “C2+” [vol %]

LHV

[MJ/

kg]

GT24/GT26 Fuel Gas FlexibilityLower Heating Value Operation Range

35 MJ / kg

50 MJ / kg

Standard fuel gas specification range

EV Burner Gas Injection Hole Modification

Figure 13 – Fuel gas flexibility-LHV

These gases have a higher reactivity, and therefore burner typically have a higher risk of flashback or exceeding emissions limits. Again, high C2+ gases require no hardware modifications to the burners the only requirement is to adapt the operating concept according to the amount of C2+ present. In the range between 6 to 9 %,




Change of operatingconcept forburner protectionG

asco

mpo

sitio

nm

onito

ring

GT24/GT26 Fuel Gas FlexibilityHigh Hydrocarbons “C2

+” Operation Range

24

28

32

36

40

44

48

52

0% 2% 4% 6% 8% 10% 12% 14% 16% 18%

LHV

[MJ/

kg]

6% 9%

High Hydrocarbons “C2+” [vol %]

Adaptive operation concept for C2+ contentNo hardware changes for C2+ gases

Figure 14 – Fuel gas flexibility-C2+

We use a gas chromatograph in order to monitor the gas composition. For C2+ gases >9 % the engine is adjusted and controlled according to the actual C2+ content in order to avoid SEV flashback. As fuel gas supplies with high C2+ also tend to have sudden and large variations in C2+, we developed an application using a fast reacting infrared measuring system, which can adjust the engine to real-time variation in the fuel composition. We have significant field experience with these systems and engines have demonstrated their ability to remain in stable operation even during sudden and high changes in the gas composition

For high C2+ content fuels, we developed a novel IR gas sensor as a precaution during the fuel flexibility test campaign at the company’s Gas Turbine Test Centre. The sensor was designed to provide gas composition data more rapidly than the standard gas chromatograph. The IR sensor recorded and transmitted any changes of the gas composition at the gas mixing plant faster than the gas reached the fuel distribution system of the engine. The data in this slide shows data taken from a customer site using the infrared system.


The data represents a situation where several stages of a gas separation plant occurred causing the C2+ content to change from 10 to 16% within 30 seconds at the GT. That separation plant was located 90km upstream of the gas turbine requiring a flow time of 45 minutes. The red line shows the corresponding automated adjustment of the SEV burner inlet temperature in response to the difference in gas composition.



GT24/GT26 Wide Operation RangeExperience with Non-Standard Fuel Gas

Wide experience range allows fluctuation of interchangeability parameters: +/-5% LHV and +/- 10% Wobbe Index

25

30

35

40

45

50

55

25 30 35 40 45 50 55Lower Heating Value [MJ/kg]

Wob

beIn

dex

[MJ/

m3 ]

GT24 Low C2+ GT26 Low C2+High C2+ Engine A High C2+ Engine EHigh C2+ Engine B High C2+ Engine FHigh C2+ Engine C High C2+ Engine GHigh C2+ Engine D High C2+ Engine H

Standard Fuel SpecRange

Wobbe Index at site specific fuel gas temperature

+/- 5%

+/- 10%

Figure 15 – Wide operation range

Summarizing our company’s wide range of experience with non-standard fuel – we come back to the two main inter-changeability parameters – LHV and WOBBE Index. A key advantage of the GT24/GT26 is not only the wide fuel specification but also the allowable fluctuations within that range even during operation – setting a standard in its class. Simple hardware solutions are available for fuels outside the gas specification. So we have seen that the GT24/GT26 provides a solution for a wide variety of fuels, but how about the influence on environmental factors such as emissions? A comparison of engines operating with high C2+ fuels with an engine operating with standard fuel gas shows that fuel composition has no impact on emissions at full load or at part load.




GT24/26 Operation Experience Reliable with High C2+ and/or High Inert Gases

CH4 82 vol %C2+ 16 vol %Inerts (N2, CO2) 2 vol %LHV 48 MJ/kg

GT24 ( 60Hz)

ALSTOM Gas Turbine Test Center 1 X GT26

15105Number of GT24/GT26 Engines with non - standard gases

More then 150’000 OH accumulated experience!

TotalGT26GT24

15105Number of GT24/GT26 Engines with non - standard gases

More than 200’000 OH accumulated experience!

GT24 GT26 Total

More than 1,200’000 OH accumulated total fleet experience!


Trinidad LNG - Sample Specification


UAE LNG - Sample Specification


GT26 ( 50Hz)


GT26 ( 50Hz)

Figure 16 – Operation experience

Summarizing, our company has fifteen (15) GT24/GT26 engines in field, which are successfully running on non-standard fuel gases, and these have now accumulated more than 200’000 fired hours in a fleet that has more than 1,200,000 OH experience. Taking a few examples, the GT24 engine at Termobahia in Brazil, is running with 16% C2+and finally the two GT26 engines at Bowin in Thailand uses fuel with both, a high inerts of 19% and a high C21 content of 14% - (each engine has 15’000 OH) and of course all of this was fully tested beforehand in the GT26 at our company’s Test Centre in Switzerland. References:

1. Powergen International, Orlando “Power Plant Technology”, Nov/Dec-2004 2. 14th Annual Latin America Energy Conference “La Jolla” May 2005.

Documents

FUEL FLEXIBILITY AND GAS TURBINE TECHNOLOGY … · FUEL FLEXIBILITY AND GAS TURBINE TECHNOLOGY (Externalities of fuel gas composition) Jonathan Lloyd Director of Marketing & Strategy