Engine Fundamentals Fundamentals II - 2018... · Awareness drives emissions standards around the...
Transcript of Engine Fundamentals Fundamentals II - 2018... · Awareness drives emissions standards around the...
April 3, 2018
Dr. Anthony J Dean, PhD
Combustion Summer School 2018 – Day 3
Engine Fundamentals…….Powering & Moving Our World
Plan for Today
Morning
• Propulsion and Power Context
• Global Trends & Drivers for Change
• Combustion Systems
• Combustion Design
Afternoon
• Gas Turbine Engine Design Workshop
Imagine….Propulsion
Next Generation Air-breathing Combustion
…. More efficient, lower emissions: GE 9x 1st flight in 2018
I-A - First U.S. jet engine
1941: 1st US jet engine
1958/1965: 1st Mach 2 and 3Supersonic Propulsion
Jet Engine Propulsion
1903: Washington to Tokyo in 3 months
1903: Wright BrothersReciprocating engines
Powered Flight
GE90-115
2006: Washington to Tokyo in 12 hours
2003: GE 90-115B
Largest & Quietest
Low Low High High CombustorLow Low High High Combustor
GE90-115
2018 – H and J-class combined cycle gas turbines
2016 article: http://www.powermag.com/siemens-ge-mhpsa-advance-gas-power-efficiency/?pagenum=2
• Pressure ratio 20-30
• Power (Simple Cycle) 350 – 500 MW
• Efficiency (Combined Cycle) >60%
1939: 4MW at 17.4% efficiency….2018: 1188 MW at 63.08% (3 GT in 1 CC plant)
Imagine….Power Generation
• Pressure ratio 4.4
• Power 4MW
• Efficiency 17.4%
1939 – 1st commercial power generation gas turbine (Switzerland)
1188 MW 2.7 million average homes in Japan
Global Trends
• Competitive Pressure - Fuel Usage & Fuel Prices• GHG Awareness• Clean Air Awareness• Unconventional Oil & Gas• Biofuels
Combustion Moves and Powers our World…..continued growth projected through 2035
Source: BP 2017
• Growth in developing regions will offset declines in developing world
• Gas: projected growth- 1.2B people still without reliable
power
• Oil: growth in Aviation- passenger-mile traffic continues to
grow
Source: BP statistical Source of World Energy 2015
Cost: Global Demand and Fuel Price Volatility
Cost focus drives innovation for efficiency
Green House Gas Awareness (CO2, CH4, ….)
Drives innovation for efficiency and alternative fuels
http://cdiac.ornl.gov/
Air Quality Awareness
http://aqicn.org
April 1, 2018: http://aqicn.org/
Air Quality Awareness
Awareness drives emissions standards around the world
April 1, 2018: http://aqicn.org/city/uae/al-ain/islamic-institute/
“The Age of Gas” – The Rise of Unconventional Gas
Drives innovation for fuel flexibility
Source: US Energy Information Administration
U.S. Total Natural Gas Proved Reserves (2007-2016)
Increasing Share of Shale Gas
Trends: Growth of Biofuels and Fischer–Tropsch Fuels
Drives innovation for fuel flexibility Source: BP statistical Source of World Energy 2015
~0.5% of current global fuel usage
Trend ImplicationDemand for lower cost of ownership - advanced engines with lower operating (fuel) cost (and lower CO2)
Emissions Regulations (NOx, PM, etc) - has driven 25+ years of combustion technology
Paris climate agreement (CO2) - Government incentives and target toward fuel displacement & more efficiency
Design Implications of Trends
Gas Turbine – Brayton Cycle Primer
Source: Wikipedia
Source: Wikipedia
Drivers of Higher Efficiency
↑ Temperature
↑ Pressure Ratio
↑ Component Efficiencies
Demand for More Efficient Engines
Ideal Brayton Cycle
16 /Source: General Electric GER-4194
2010 2015 2020
“H” (steam)
Cycle Efficiency Advances: Gas Turbines w/ Bottoming Cycle
“HA”
World records
62.2% (50 Hz)
63.08% (60 Hz)
Inlet
• Broader range of T3, P3
Outlet
• Higher Turbine Inlet
Temperature
Consequences of Advanced Cycles
18 /
Combustion and Emissions
from Fuel from Air
Re
ac
tan
ts Fuel Air
No
rma
l
Pro
du
cts
CO2 Water Nitrogen Excess Oxygen
Un
inte
nd
ed
Pro
du
cts
UnburnedHydrocarbon
CarbonMonoxide
Oxides of NitrogenNOx
Soot(Particulate)
To
tal P
rod
uc
ts
Normal and unintended products of combustion
Source: Roy Primus, GE
Combustion and EmissionsGas Turbine exhaust emissions burning conventional fuels.
Source: General Electric GER-4211
Ground-based Emissions Requirements – World Bank
Local emissions regulations often more stringent (eg California)Source: World Bank
Aviation NOx Emissions Requirements
Evolution of Landing and Take-Off (LTO) Cycle Engine NOx Emissions
ICA
O N
Ox
sta
nd
ard
s (g
/kN
)
Source: ICAO https://www.icao.int presentation by Dr. Neil DicksonICAO Air Transport Bureau
Paris Climate Accord & Aviation CO2 Emissions
• March 2017: ICAO Council adopts new CO2 emissions standard for aircraft
• Applies to new aircraft type designs from 2020, and aircraft already in-production as of 2023.
• Aircraft in-production aircraft which by 2028 don’t comply Source:https://www.icao.int/
Meetings/EGAP/Presentations
Mix of Fuel Types in the Future
Source: BP 2017
• Rise of cost - effective Renewables: - leading to market uncertainty for combustion devices in energy markets- market opportunity for biofuels
• “Age of Gas”: reduced coal use, and liquid fuels
Biofuels fuels for propulsion … promisingSuitable fuels must …
• Result in less carbon
• Be delivered in quantity
• Be cost effective
• Compatible with food production
Timeline of Aviation alternative fuels
Algae … a potential source?
Source: ICAO
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Fuel Effects on Combustion System Performance
Atomization
Reaction
Evaporation
LBO/
Ignition
Liner
Temperatures
Exit
Temperature
Profiles
Smoke/
Particulates
Gaseous
Emissions
Nozzle
CokingSmoke
Point
Viscosity
Aromatics
Vapor
Pressure
Distillation
Profile
Density
Freezing
Point
Heat of
Combustion
Processes
Particles
Surface
Tension
Atomization
Reaction
Evaporation
LBO/
Ignition
Liner
Temperatures
Exit
Temperature
Profiles
Smoke/
Particulates
Gaseous
Emissions
Nozzle
CokingSmoke
Point
Viscosity
Aromatics
Vapor
Pressure
Distillation
Profile
Density
Freezing
Point
Heat of
Combustion
Processes
Particles
Surface
Tension
PerformanceFuel Properties
CombustionDynamics
Many Linkages Between Fuel Properties and Combustion Performance
From OEM presentation to National Jet Fuels Combustion Program
Alternative gaseous fuels•Fuels characterized by the heating value and constituents:
– Modified Wobbe index < 40 or > 60
– Low to med BTU fuels, LHV < ~800 BTU/SCF
– High BTU fuels, LHV > ~1200 BTU/SCF
• High H2 fuels > 5% by volume
• High CO, CO2, N2, C2+
Refinery, Process
Off Gases
• High H2, CO2, CO
LNG, Associated
Flare Gas
• High C2+
LNG
• High N2, CO2
COG, Low BTU
Syngas
• High H2, CO2, CO
Modified Wobbe Index=
LHV/ (MWgas/28.96 * T)^0.5
Combustion Systems
GT Combustor Architectures• Ground-based Gas Turbines• Aircraft Engines
Source: General Electric GER-4194
Ground-based Gas Turbines
• Silo Combustor
• Can-annular Combustor
• Annular Combustor
GE 7FB Gas Turbine
Combustion System Architectures
Diffusion Can Combustor• Rich burning• up to 300 ppm NOx•Highly fuel flexible•No staging
GT Combustor Technology Evolution
DLN-1 Combustor• Axially Staged Combustion • 3-25 ppm NOx• E-class Gas Turbines
DLN-2 Combustor• Fully Premixed Combustion• 9-25 ppm NOx• F,H-class Gas Turbines
Inlet Flow Conditioner
Diffusion Swirler
Diffusion Gas Holes
Swirler Vanes
Premix Fuel Passages
Source: General Electric GER-4194
Low Emissions Combustor Flame Structure
• Flame imaging of low emissions combustor
• Multiple fuel nozzles in each combustion chamber
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Reheat Gas Turbine
Alstom GT24/26 • Annular Combustor• Sequential Combustor
Aircraft Engine Approaches to Reduced Emissions
• More fuel injection points
• More air to combustor dome
• Fuel system complexity (staging)
Single Annular Combustor (SAC)• Rich burning• 54% of CAEP/2 NOx (Tech In.)• Proven performance• No staging• 3M+ flight hours (LEC)
CFM56 DAC
GEnx
CFM56 SAC
Aviation Combustion Technology Evolution
Dual Annular Combustor (DAC)• Lean burning• 47% of CAEP/2 NOx• Shorter combustor• Radial & circumferential staging• 3M+ flight hours
Twin Annular Premixing Swirler (TAPS)• Lean burning• 42% of CAEP/6 NOx• Shorter combustor• Staging within the swirler
Balance reduced emissions with operability, durability, cost and weight
Aviation gas turbine combustion
• Flame imaging
• Flame structure changes with fuel staging
Combustion Development
36GE Title or job number
4/4/2018
Gas Turbine Combustor Design Requirements
Fuel Property Interactions
Complex physics and non-linear interactions
• Huge range of time and length scales
• Trade-offs to achieve design balance and meet product requirements
Balanced Design enabled by Analysis and Validation
Gas Turbine Combustion Challenges
Flame must be anchored in the equivalent of 100 mph wind
Chemical reactions must occur in a fraction of a second as air and fuel flow through the combustor. How fast?
3-25 ms
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Combustor key physics
Turbulent subsonic
flow
Swirling turbulent
flow with heat
release
Fuel-air mixing
Emissions
chemistry
Acceleration to
sonic conditions
Radiant energy
transfer
Combustion
Ignition,
Extinction and
Stability Turbulence-
chemisty
interactions
39 /
Emissions: NOx Fundamentals
NOx Formation Mechanisms• Zeldovich Mechanism (air at high T)
• Prompt-NOx (CHx+N2)
• Fuel-Bound Nitrogen (FBN)
Source: General Electric GER-4211
Fenimore Mechanism
40GE Title or job number
4/4/2018
Prompt NOx Discovery - Charlie Fenimore
CH+N2 HCN + N
Role Model Industrial Research Career
• Discovered “Prompt-NOx”, the reaction of N2 with CH radicals
• Used porous plug burner to create 1D, well-characterized, premixed flames.
• Made it possible to understand at devise pratical approaches to reduction of smoke and other emissions.
Awarded the Combustion Institute Bernard Lewis Gold Medal in 1974 for “brilliant research in the field of combustion, particularly mechanics of elementary reactions.
NOx Control Technologies
Relative Cost Impact
Lean Premixed Combustion is Preferred Solution
Source: EPA 456/F-99-006R
Strategies to Reduce Nox
• Lower Peak Temperature
• Premix Fuel and Air
• Reduce O2 Concentration
• Reduce Residence Time
• Less Time at Temperature
• Cleaner Fuels
• No Fuel-Bound Nitrogen
• Staged Combustion
• Aftertreatment
Combustor Design Approaches to Lower Emissions
Key Constraints
• More fuel injection points
• More air to combustor dome
• Fuel system complexity (staging)
Combustor Operating Window
NOx
CO
Hot Tones
Cold Tones
Acceptable Limits
Op
era
tin
g w
ind
ow
wit
h a
cc
ep
tab
le
em
issi
on
s a
nd
dy
na
mic
s
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Emissions Advances: Gas Turbines
Heavy Duty Gas Turbine
Source: General Electric GER-4194
E-Class: 25 ppm 3 ppm
HA-Class: 25 ppm
F-Class: 25 ppm 5 ppm
Baseline: 100’s of ppm
45 /
Combustor Design & Validation Process
Non-reacting
Simulations
Sub-System
Full Annular Rig
Can Combustor
System
Full Engine
Component
Single Nozzle
Sector Rig
Sub-Component
Non-reacting
Rigs
Reacting
Simulations
0D. 1D
Analysis
46 /
Additive Technology Driving Innovation
• Direct Metal Laser Melting (DMLM)
• Start with a metal powder and form a metal part directly
• Enables fast cycle time from idea to hardware
• Enables novel geometries - part complexity is “free”
Case Study – Fuel Nozzle
Combustion System Technology Drivers
• Fuel Efficiency (Cost, CO2)• Emissions regulations (NOx, PM)• Fuel Type (Resilience)• Durability (Cost, Reliability)• Operability (Flexibility)
Many Drivers and Opportunities to Create New Technology
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Gaps & Opportunities in Combustor Design
Advanced Cycles• Need fundamental combustion data at relevant conditions (>20 bar)• Highly turbulent combustion and super-sonic combustion• Multi-physics design tools (range of time and length scales)
Emissions Regulations• Lean premixed combustion – reaching entitlement• CO2 becoming an “emission”
Fuel Flexibility• Need chemical kinetics for all fuels• Mixed-modes of combustion
Need multi-physics design tools anchored with data
New additive manufacturing enables faster design cycles
49 /
Questions?