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Authors: Gerhard Fruechtel, Alice Pesenti, Paolo Traverso

Speaker: Paolo Traverso

The path forward to more efficient combustion in very Large GT

COMPANY

CONFIDENTIAL 27.09.2016

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High Efficiency and Low Emissions

in Gas Turbines

Why to talk about combustion ?

COMPANY

CONFIDENTIAL

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2016 Combustion Portfolio

1) Hybrid burners for class E & F class

2) EV Alstom technology for 1st stage in F & H class

3) SEV combustion technology for F class

Ansaldo Energia is today owner of following combustion technologies:

4) SEV combustion technology for H class

5) Flamesheet for F & H class owned by PSM

6) G-Top combustor owned by PSM

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CONFIDENTIAL

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Ansaldo Energia is today using following combustor architectures:

1) Silo combustors (horizontal & vertical)

3) Double stage dual pressure

Annular combustors

2) Single stage Annular combustors

5) Double stage Cannular combustor

2016 Combustion Portfolio

4) Single stage cannular with Flame sheet options

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CONFIDENTIAL

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CONFIDENTIAL

AE fleet with Hybrid burners

Overview and improvements to F class GT

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Dual Fuel Burner (diffusion/pilot+premix for both fuels)

Parallel Air Paths for diagonal and axial sw.

NG Premix

LFO Premix

NG Diffusion

NG Pilot

LFO Diffusion

NG Igniter

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EMISSIONS AND PERFORMANCE: S.A.S. UPGRADE

Ansaldo Energia s.p.a. reserves all rights on this document that can not be reproduced in any part without its written consent

AIR SAVING ~ 15 kg/s

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VeLoNOx 1A / HR3 + diagonale Low Swirl

HR3 line

4 pipes fed with pilot gas

VeLoNOx 1° lines

4 couples of 3 mm holes

Low Swirl 9 holes (+2°)

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Achievements – CFD + RIGs + Field Validation

• Additional fuel line (gas lance) -> Increased load variation capabilities & stability at B.L. –

Escatron 2014 –Sousse 2015

Fuel gas lance development

Upgrade Design of 50Hz F-class GT AE94.3A

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CONFIDENTIAL

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CONFIDENTIAL

EV & SEV

in the past

for the present

and for the

Large GTs of the future

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EV and SEV technology (Former Alstom)

Single Burner

Silo Combustor

Dry Low NOx Burners

Annular Combustors

1st Generation

Can-annular Combustors

Sequential Combustion

2nd Generation

EV Burners AEV Burners

CPSC Reheat Engine

GT13E GT11N2

GT8C

GT13E2

GT8C2

GT24 / GT26 GT36

SEV Burners

Gas Turbine Burner Development from 500 ppm NOx to 10 ppm NOx and from 20 MW/m3 to > 200 MW/m3

Sequential Burner

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Gas Concentration

Profile

stage 2

stage 1

Lean Premix Mode

• Low NOx emissions • Fuel is evenly distributed

• Almost no sensitivity to

Wobbe index changes • Flame positions shifts slightly

with increasing reactivity of fuel

Rich Premix Mode

• Start-up with high fuel concentration on axis

• Transfer to Lean operation at 5% GT load

stage 2

stage 1

GT26 EV combustor – operational flexibility

EV Burner – fuel injection into swirling air crossflow Premix from idle to full load without switch-points

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GT26 SEV combustor – operational flexibility

Flamefront Mixing zone

Vortex generators

(VGs)

Hot gas from high pressure turbine

Fuel gas, Carrier air

Combustion chamber

No sensitivity to Wobbe Index

• Carrier air is surrounding the fuel jet to enhance penetration > 50% of jet momentum

SEV flame position reacts to C2+/H2 content

• Flame shifts upstream with increasing reactivity

• Flame position controlled by EV/SEV fuel split (C2+ standard operation)

SEV Burner – fuel injection into crossflow with longitudinal vortices

Auto-ignition operation from 10% to 100% relative GT load

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SEV combustor - principle of reheat combustion

SEV flame position is controlled by the variable EV/SEV fuel split

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GT26 Operational Flexibility Improvements

Overview of Extended Load Ranges

A new enhanced operation window without lifetime penalization

Low Load

Operation (Parking)

Low Part Load

Original

Operation window

GT

Lo

ad

(%

)

100%

LLO

Low part load

MEL*

MEL*

0

CO emission limits

exceeded

Baseline Dispatch

Window

Enhanced

Operation window

* MEL : Minimum Environmental Load at 100 mg/Nm3 CO and a natural gas with C2+ 6%

High Fogging

Steam Injection

- 15 %

+ 5 %

+ 6 %

40* - 100 %

10 %

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GT26 Operational Flexibility Improvements

Overview of Extended Load Ranges

The challenge

• At low part load, the SEV Burner

temperature with all burners in

operation is low and causes

incomplete combustion resulting in

increased CO emissions

The solution

• Sequential switch-off of SEV

burners at lower loads

• Reduced power output while

keeping SEV burner temperature

on high level

Optimized low CO emissions

EV

SEV

ca. 15% 25% 40% 100%

GT rel. load

Typical CO limits

GT26 CO emission

SEV Burner temperature

(standard concept)

SEV Burner temperature

(partial burner switch off)

EV – first combustor

SEV – second combustor

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Fuel Gas Flexibility

• Wobbe Index variation tolerance of over +/-15% (31-52 MJ/m3 absolute)

• C2+ variation tolerance up to 18% vol.

• C2+ standard operation covers H2 contents of 5% vol.

• Hydrogen contents of 15% vol. can be handled

Liquid Fuel Flexibility

• Wide experience range within the GT fleet

• Boiling ranges from Naphtha to Kerosene to Oil#2 can be covered

• On GT26 fuel switchover (gas oil) at high loads commercially proven

GT26 Gas Turbine Fuel Flexibility

Superior fuel flexibility proven for GT26

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GT36 Gas Turbine

Evolution of sequential Combustion with CPSC

GT26

GT36

Sequential Combustor Compressor Turbine

Premix

Combustor

Proven benefits of Sequential Combustion:

• Sub 25vppm NOx emissions at plus 1500°C hot gas temperature

• Turn Down to < 25% GT load

• Parking at < 5% GT load

• Fuel Flexibility – Wobbe Range 31-53MJ/m3, ±15%, LHV 29-50MJ/kg

CPSC – additional benefits:

• High pressure cycle removed, eliminating 340 hot gas parts and 1’500 structural parts

− Reduced compressor exit temperature by 90K (160ºF)

• Service orientated GT concept enabling fast hot gas path inspection of 13 days

• Improves rig to engine transferability of combustor behaviour

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Van

e

1st combustor Seq. Burner Seq. Combustor Mixer

GT36 Combustor Constant Pressure Sequential Combustion – Function

• CPSC (SEV) advantage on trade-off between NOx and CO

− Sequential burner technology allows very low residence times, with good CO burnout, without

staging.

− Sequential combustion (with higher secondary burner inlet temperatures and depleted inlet air

O2) permits short residence times for secondary combustor and potential for ultra low NOx.

− NOx emissions at part load are minimal due to the absence of pilot/staging needs.

Temperature

trend

Optimized Residence Times

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Combustor: Design

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CONFIDENTIAL

GT36

Premix Combustor

Sequential Combustor

Based on F-class can combustor and proven GT26 sequential combustors

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Reheat burner technology

Multi-Point In-Line Injection with Small-scale mixing devices

• Lowering pressure loss • Enhanced flashback margin • Carrier air reduction • Higher engine performance • Capable of addressing highly reactive fuel • 70/30 H2/N2 demonstrated on HP rig

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HBK5 Test Facility Cologne

Key Parameters

Air mass flow 70 kg/s

Pressure 40 bar

Preheat Temperature 700 °C

Hot Gas Temperature 2000 K

Fuel Types gaseous & liquid

Thermal Power 125 MW

A test facility designed to industry needs

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A new generation is born New products.

New technologies.

New service capabilities.

Ansaldo Energia: a global player in the power generation market.