An Introduction to Gas Turbines – Fuel Flexibility · 2016-11-16 · Siemens gas turbine models on a wide range of gas fuels ... depending on gas turbine model • SGT-500 able

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An Introduction to Gas Turbines – Fuel Flexibility

Richard Williamson, Geraldine Roy, Siemens Ind.Turbomachinery Ltd.

2016-11-15

Restricted © Siemens AG 2016 All rights reserved.

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• Introduction 3 • Gas Turbine portfolio 4 • Gas Turbine design 6 • Gas Fuel Flexibility in DLE 16 • Gas Fuel Contaminants 24 • Liquid Fuel Challenges 28 • Summary 34

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First established in 1857 - Joseph Ruston Gas Turbines since 1946 - Frank Whittle

Gas Turbines

Agriculture

Military Transport

Industry

Gas Turbine heritage

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Gas turbine portfolio

SGT-500 (19/19 MW) SGT-600 (24/25 MW) Industrial RB211 (27 to32/28 to 34 MW) SGT-700 (33/34 MW) SGT-750 (38/39 MW) SGT-800 (48 to 53 MW) Industrial Trent 60 (53 to 66/54 to 62 MW)

Industrial 501 (4 to 6 MW) SGT-100 (5/6 MW) SGT-200 (7/8 MW) SGT-300 (8/8 MW) SGT-400 (13 to 14/13 to 15 MW)

SGT6-2000E (116 MW) SGT6-5000F (242 MW) SGT6-8000H (296 MW)

SGT5-2000E (187 MW) SGT5-4000F (307 MW) SGT5-8000H (400 MW)

50 Hz

60 Hz

50 or 60 Hz

Gas turbines in the range of

0-15 MW


16-99 MW


100-400 MW

Aeroderivative gas turbines

Industrial

gas turbines

Heavy-duty

gas turbines

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World class innovative solutions with strong footprint in all industries

Chemicals Pulp & Paper

Manufacturing Food & Beverage, etc.

Electric Power Utility Independent Power

Producer Municipality

Installed fleet [units] ~ 1,700 ~ 950

Industrial Power Generation

Up-Stream Mid-Stream

Down-Stream

Oil & Gas

~ 1,400

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Gas Turbine package design

Gas and Liquid Fuels

Combustion Air

Exhaust Gas

The fluids entering or exiting the gas turbine core or package influence both turbine performance and environmental impact

• Fuel contamination

• Exhaust Pollutants

Wet Abatement methods

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Gas Turbine - SGT-400 core engine design

Compressor Combustion system Gas Generator Turbine Power Turbine

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Industrial and Aero-derivative gas turbine combustion

• Originally both diffusion flame design

• Reverse flow / In-line design

• Design Driven by Legislation and company policies in a move to Low Emissions Combustion technologies

• Varying complexity of DLE systems

Combustion systems

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Combustion Mode Operation

PRE - MIX

PRIMARY

DIFFUSION PRE - MIX

LEAN -LEAN SECONDARY PRE - MIX

Lean Pre-mix

Mode switching

Stage combustion

LOAD

Modes of combustion operation(Illustrative purpose only)

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Combustors

Examples of staged, pre-mix annular and pre-mix cannular combustors

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Combustion systems

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Gas Turbine Combustor – Dry Low Emission technology

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• Introduction 3 • Gas Turbine portfolio 4 • Gas Turbine design 6 • Gas Fuel Flexibility 16 • Gas Fuel Contaminants 24 • Liquid Fuel Challenges 28 • Summary 34

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0%

20%

40%

60%

80%

100%vo

l %

Tailgas

Blast furnace

Air blown gasific

ation

Steel process

Syngas / O2 gasific

ation

Wellhead - V

ery High Inert (

50-85%)

Landfill / d

igester / sewage

MCV Refinery

Wellhead - H

igh Inert (

25-50%)

Coke Oven H2 NG

NG with H2

LNG

HCV Refinery

Wellhead - H

igh hydrocarbon

HCV ProcessLPG

CO2N2COH2C3H8C2H6CH4

Fuel Type Various fuel types - Gaseous Fuels

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Gas Fuel Flexibility

• Lean gases have a potential positive impact on gas turbine performance • Rich gases have a slight negative impact

• DLE Combustion systems, offering low emissions, available on most Siemens gas turbine models on a wide range of gas fuels

• Not at present for fuels with high H2 (>15%) and CO content such as syngas or Coke Oven Gas – diffusion flame only

Low Calorrfic Value (LCV) Medium Calorrfic Value (MCV) "Pipeline" Quality High Calorific Value (HCV)

Reference Nat Gas

Siemens Gas Turbine Solution

'Rich'Gas- higher content of C2+ constituents

'Lean' Gas- High Inert content- Coke Oven Gas (COG)- Synthetic Gas (Syngas)

85% Inertcontent gas

50% CH450% N2 'LNG'

100% C3H8COG

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10 20 40 50 60 7030Wobbe Index (MJ/Nm³)

3.5 37 49 65

Low NOx Units operating

Standard DLE fleet Capability

Siemens Diffusion Operating Experience

Air blown Biomass

Gasification Landfill &

Sewage

Gas

High Hydrogen

Refinery Gases

LPG

Off-shore rich gasIPG CeramicsOff-shore lean

Well head gas

Diffusion flame operating units

DLE operating units

Off-shore SE Asia

lean well head gas

Coke oven gas

high Hydrogen

Tri fuel SGT-300

PLG/NG/Liquid

Ethane

Gas Turbines burns a wide range of fuel

Low Calorrfic Value (LCV) Medium Calorrfic Value (MCV) "Pipeline" Quality High Calorific Value (HCV)

Reference Nat Gas

85% Inertcontent gas

50% CH50% N 'LNG'COG

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Alternative Gas Fuels: Case Study 1

University of New Hampshire, USA

• Tri-generation plant to provide power, heat and cooling to University campus

• Low emissions requirement • 15ppm NOx

• Originally envisaged to operate on natural gas with diesel fuel as back-up

• University made aware of availability of local source of landfill gas as low cost fuel

• Gas fuel system able to operate on processed landfill gas as well as natural gas

• Wobbe Index down to 30MJ/Nm3 acceptable • Variable composition as source gases

occasionally blended to boost heating value

Siemens SGT-300 tri-fuel DLE gas turbine

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Ethanol Processing Plant, China

• Process produced waste biogas • 60% methane (CH4) • 36% carbon dioxide (CO2)

• Wobbe Index of 21MJ/Nm3 indicates energy content approximately 50% that of natural gas

• Siemens SGT-400 Dry Low Emissions combustor tested to prove satisfactory operation and start capability

• Biogas fuel only configuration

• Cogeneration plant entered service May 2013

Siemens SGT-400 in operation on a weak gas fuel, China


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Chemical Plant, China

• SGT-700 gas turbine to operate on process off-gases

• Highly variable composition • High levels C2, C3, C4 encountered • Variable gas composition catered

for in standard DLE combustion hardware

0

25

50

75

100

1 2 3 4 5

CH4C2H6C3H8C4H10H2

Mol %

Selection of Gas samples seen by an SGT-700 over 8 month period


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Sulphur

Sulphur is a commonly present contaminant

• Gaseous fuels typically as H2S or mercaptans • Liquid fuel as elemental sulphur or mercaptans • Sulphur may also be present in air !

• General observations • H2S is poisonous - even in small quantities • On its own is relatively benign to a turbine combustion

system • ‘What goes in comes out’ • Combusts producing SOx emissions

• SOx is regulated in many parts of the World • In the presence of water can result in the formation of

acids • H2S + O2 + H2O -> H2SO3 or H2SO4 => Acid Rain

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Sulphur

Sulphur reacts with other contaminants to produce corrosive compounds

• Presence of Na + K => sulphates which are highly corrosive to modern turbine materials • Fuel treatment at source may be required • Less corrosive to high chromium content material

• Presence of Va = complex corrosive vanates Combustion chamber inspection after 15000 OH ▪ Partial loss of TBC on inner/outer liner and

on the heat shield

▪ Base material has not been affected

▪ Combustion chamber was changed according to plan

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Fuel Contamination Issues

DLE Combustion Pre-Chamber Failure

• Attributed to hydrocarbon carry-over • Poor control of dew point

DLE Pilot / Main burner with carbon formation • Attributed to hydrocarbon

carry-over

• Poor control of dew point

Main Burner

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• All models able to operate on high quality liquid fuels such as diesel and kerosene • Emissions abatement available either from “dry” (DLE) or “wet” (WLE) depending on gas

turbine model • SGT-500 able to operate on poor quality liquid fuels such as HFO and crude oil

• Up to kinematic viscosities of around 1000cSt @ 50°C

Liquid Fuel Flexibility

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Liquid Fuel Challenges

Carbon Residue • Carbon Residue is the percentage of coked material remaining after

a sample of fuel has been exposed to high temperatures • Indicates:

• The tendency of fuel to form carbon deposits during combustion • Complexity of hydrocarbon constituents in the fuel • Difficulty in combusting the fuel and time for complete combustion • Affects ability to operate at low loads • Causes Incomplete combustion • Difficult to ignite

• High Carbon Residue content may require start-up on a more conventional fuel

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Liquid Fuel Challenges

Other Contaminants • Alkali metals

• Dissolved in water present in the fuel • Create corrosive constituents during combustion that deposit on hot section components • Can be removed by water washing and centrifuging

• Heavy metals (Vanadium etc) • Dissolved in the oil itself • Create corrosive constituents during combustion that deposit on hot section components • Corrosive effect reduced by chemical dosing (adding magnesium-based inhibitors)

• Water • Free water can lead to corrosion and fuel degradation, and encourage microbial growth that

produces a corrosive slime • Employ proper fuel storage and handling system design

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Liquid Fuel

House keeping / storage

• Quality control procedure • Fuel specification • Cleanliness • Monitoring / recording

• Delivery • Tankers used for same fuel • No cross contamination

• Storage • Receiving and settling tanks • Centrifuge, filter, coalescer fitted to minimise impact of

water and particulate matter

• Forwarding • Day tanks • Fine filtration (polishing) applied to each tank

Property Unit Specification TestMin Max

Cetane Number 52 54 ISO 5165

Density @15°C kg/m3 833 837 ISO 3675

Distillation (vol. % recovered) °C ISO 3405

- 50% point 245 -

- 95% point 345 350

- final boiling point - 370

Flash point °C 55 - EN 22719

CFPP °C - -5 EN 116

Viscosity @40°C mm2/s 2.5 3.5 ISO 3104

Polycyclic aromatic hydrocarbons % wt. 3 6 IP 391, EN 12916

Sulfur contenta mg/kg - 300* ISO/DIS 14596

Copper corrosion - Class 1 ISO 2160

Conradson carbon residue (10% DR) % wt. - 0.2 ISO 10370

Ash content % wt. - 0.01 ISO 6245

Water content % wt. - 0.05 ISO 12937

Neutralization (strong acid) number mg KOH/g

- 0.02 ASTM D974-95

Oxidation stability mg/ml - 0.025 ISO 12205* sulfur limit of 50 mg/kg effective 2005 (Euro 4)a - the actual sulfur content must be reported

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Liquid Fuel Storage

Receiving and settling tanks ▪ Floating Suction

▪ Sloping bottom

▪ Water / Sediment take off-point / drain

▪ Centrifuge, filter, coalescer fitted to minimise impact of water and particulate matter

Settling / Day Tank (if used) ▪ Design as for main tank, including all

best practice features

▪ “Polishing” system comprising aspects such as centrifuge, filter

▪ Polishing applied regularly to ensure water/particulate kept to minimum acceptable level

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Summary

Take a holistic view when understanding the use of gas turbines • Understand all sources likely to

influence GT operation Maximise reliability and availability by working closely with customers • Understand customers needs • Many fuel compositions are possible,

please refer to us for advice. Gas Turbine OEM’s are there to help

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Thank you for your attention !

Richard Williamson Framework ManagerPG DG GCS TIS Ruston House, Waterside SouthLincoln LN5 7FD, United Kingdom Phone: +44 (1522) 584213E-mail: [email protected]

siemens.com/energy

Documents

An Introduction to Gas Turbines – Fuel Flexibility · 2016-11-16 · Siemens gas turbine models on a wide range of gas fuels ... depending on gas turbine model • SGT-500 able