High Temperature Oxidation and Corrosion of Gas Turbine Materials in Burner Rig Exposures
Joy SumnerAdriana Encinas-Oropesa
Nigel J. SimmsJohn E. Oakey
Cranfield University
8th International Charles Parsons Turbine
ConferenceSeptember 2011
BackgroundIntegrated Gasification Combined
Cycle (IGCC) Plants:
Combined Cycle Plants
• Higher efficiency (coupling steam
and gas turbines (GTs))
IGCC
• Syngas from solid fuels
• Integration of gas cleaning to meet
environmental legislation
GT lifetime limited by
• Hot corrosion: alkali metals, SOx
• Erosion: particles
• Deposition: particles, vapour
• Creep and fatigue
• Synergistic effects
O2
supplyGasifier
Particle remover
Shift reactor
Combustor
can
Heat exchanger
Sulphur removal
FuelSteam
Bottom ash
CO2
absorber
CO2
desorberH2 co-
production
Compressor
Steam turbine
GT
Fly ash
Steam
Sulphur
CO2
compressor
CO2
storage
~
~
Air
Cooler Steam
BackgroundTraditionally, industrial gas
turbines operate on natural gas /
oil-derived fuels
• Low in ash, alkali metals, etc
• Increasing fuel cost
Alternative fuels
• Gasified coal & biomass
• Lower calorific value syngases
• More ash, S, alkali metals, etc
Higher gas operating
temperatures
• Increase power plant efficiency
Result:
• Components exposed to hotter,
dirtier combusted gas stream
0.01
0.1
1
10
100
Wt% wet Wt% dry Wt% daf Wt% daf Wt% daf Wt% daf Wt% daf Wt% daf Wt% daf
Water
content
Ash Volatiles C H O N S Cl
Fuel parameter
%
Willow Poplar
Fir/pine/spruce Miscanthus
Wheat Olive waste
Coal
0
5000
10000
15000
20000
25000
Al Ba Ca Fe K Mg Mn Na P Si Ti
Element
Co
ncen
trati
on
(m
g/k
g d
ry)
Willow Poplar
Fir/pine/spruce Miscanthus
Wheat Olive waste
Coal
UK/US Collaboration on Advanced Materials for Low Emission Power Plants
5 year project established between:
• UK Department of Energy and Climate Change (DECC)
• US Department of Energy (DOE)
Project aims:
• Study new gas turbine operating environments
• Study response of materials for hot gas path components
• Quantifying & ranking materials’ corrosion resistance
• Creating an information database for future models
Talk aims:
• Describe burner rig exposures designed to simulate GT
environments
• Assess corrosion of current state-of-the-art materials
Experimental Details: MaterialsUnder this programme:
• 24 materials systems exposed:
• 8 state-of-the-art alloys (bare
or coated)
• 9 corrosion resistant/bond
coatings
• 2 thermal barrier coatings
Wt. %
Material Ni Cr Co Al Ti Ta Mo W B C Other
Haynes
230
57 22 5 0.3 - - 2 14 0.015 0.1 Si: 0.4, Mn: 0.5
La: 0.02, Fe: 3
IN939 48 22.5 19 1.9 3.7 1.4 - 2 0.009 0.15 Nb: 1, Zr: 0.09
IN738LC 62 16 8.5 3.4 3.4 1.7 1.7 2.6 0.01 0.11 Nb: 0.9, Zr: 0.05
CM247LC 62 8.1 9.2 5.6 0.7 3.2 0.5 9.5 0.015 0.07 Hf: 1.4, Zr: 0.015
4 tests:
• Combustion gas
environments simulating 4
different fuels
• Up to 1000 hours
• In a high velocity burner rig
• Total of nearly 700 air-
cooled samples exposed
Focus on 4 materials & 3 tests
Experimental Details: Test Conditions
Parameter Units Test 1 Test 2 Test 3
Simulates Contaminated
Diesel
IGCC H2-rich IGCC
Entry Gas Temp. °C 1180 1180 1250
Gas Velocity ms-1 50 50 50
Dust Type - - Sieved PF fly
ash
-
Dust Load ppm.mg-1.h-1 - 2 -
SOX vppm 300 300 300
HCl vppm - - -
H2O vol.% 8.7 8.7 ~20
Na ppb 125 125 125
K ppb 125 125 125
Syngas upper contaminant limits determined:
• Extrapolated from current NG limits
• Corrected for reduced fuel calorific content
• Variables standardised for ease of comparison
Comment on Accelerated Tests
• Large metal losses:
• Up to 2-3 mm in 1000 hours
• Why?
• Burner rig runs an accelerated test
• Operates under atmospheric pressure
• But need the same alkali sulphate
dew points as a real gas turbine
• Therefore need more salt in the
system
• Increases the vapour pressure in the
gas stream
• Increases the deposition flux
• Therefore much higher corrosion rates
than in standard gas turbines
g
isi
ip
ppm ,.
dShDii /
i
iinis
CT
BApp exp,
ṁ, flux of condensed gaseous component, i
βi, mass transfer coefficient of component, i
pi, partial pressure of component, i
ps,i, saturation pressure of component, i
p, flue gas pressure
ρg, flue gas density
Sh, Sherwood number
Di, diffusion coefficient of component, i
d, diameter on which component, i, condenses
pn, 105 Pa
Ai, Bi, Ci, constants
T, absolute temperature
Experimental Details:Burner Rig
Water cooling Dilution & cooling air
Dilution &
cooling airWater
cooling
Vent
Temperature &
pressure monitoring,
gas analysisTemperature monitored
air-cooled probes
Air
Air
SO2
Liquid/vapour
contaminants
Natural
Gas
Particle
feeder
Samples exposed for:
• 300 hours
• 700 hours
• 1,000 hours
Experimental Details:Statistical Assessment of Damage via Image Analysis
XXXXXXXXXXXXXX
XXXXXXXXXXXXXX
x3
Thermocouple measures
cooling air exit temp.
XXXXXXXXXXXXXX
XXXXXXXXXXXXXX
XXXXXXXXXXXXXX
XXXXXXXXXXXXXX
XXXXXXXXXXXXXX
XXXXXXXXXXXXXX
Cooling air in
0
50
100
150
200
0 10 20 30
-∆G
M /µ
m
Data Point Number
-400
-300
-200
-100
0
100
-2 0 2
∆G
M /µ
m
Std. Normal Prob.
Hot air
out
Results:Samples Pre- and Post-Exposure
Pre-exposure
Post-exposure
Image Analysis Results:The Effect of Exposure Time
0
20
40
60
80
100
120
0 200 400 600 800 1000
GM
L /µ
m
time /hours
Good Metal Loss for CM247LC after Test 2 exposure at 755 °C
-50
150
350
550
0 200 400 600 800 1000
GM
L /µ
m
Time /hours
Good Metal Loss for CM247LC after Test 2 exposure at 955 °C
-700
-600
-500
-400
-300
-200
-100
0
0 20 40 60 80 100
ΔG
M /µ
m
Probability /%
Change in Good Metal with Time (Test 2 exposure, 955 °C)
300 hours
700 hours
1000 hours
SEM & EDX Results:The Effect of Exposure Time (Test 2, 955 °C)
300 hours
Al
Co
Cr
S
Hf
Ni
O
90 µm
700 hours
Al
Co
Cr
Ni
O
S
100 µm
1000 hours
Al
Co
Cr
Hf
Ni
O
S
100 µm
Hf
SEM & EDX Results:The Effect of Exposure Time (Test 2, 955 °C)
300 hours
Al
Co
Cr
S
Hf
Ni
O
90 µm
700 hours
Al Hf
Co
Cr
Ni
O
S
300 µm
1000 hours
300 µm
Al
Co
Cr
Hf
Ni
O
S
Image Analysis Results:The Effect of Test & Exposure Temperature
0
500
1000
1500
1 2 3
GM
L /µ
m
Test
Effect of Test on CM247LC GML (1000 hour exposure)
955 °C
755 °C
-2000
-1500
-1000
-500
0
0 20 40 60 80 100
∆G
M /µ
m
Probability /%
Cumulative Probability ΔGM after 1000 h exposure (955 °C)
test 1 (995 °C)
test 2 (955 °C)
test 3 (955 °C)
-250
-200
-150
-100
-50
0
0 20 40 60 80 100
∆G
M /µ
m
Probability (%)
Cumulative Probability ΔGM after 1000 h exposure (755 °C)
test 1 (755 °C)
test 2 (755 °C)
test 3 (755 °C)
Image Analysis Results:Comparison to Other Alloys
-1100
-900
-700
-500
-300
-100
100
0 20 40 60 80 100
∆G
M /µ
m
Probability (%)
Cumulative Probability ΔGM after 1000 h Test 3 Exposure at 955 °C
IN939
Haynes 230
IN738LC
CM247LC0
200
400
600
800
1000
IN939 Haynes 230 IN738LC CM247LC
GM
L /µ
m
GML after 1000 hours exposure to Test 3 conditions at 955 °C
Conclusions• The severity of the corrosion and oxidation conditions varied between
the three tests
Test 2 (IGCC conditions including ash particles) appeared least
aggressive
Impacting fly ash removed corrosive deposits?
• Different types of hot corrosion seen
Type I: internal oxidation & sulfidation, lower incubation GMLs
Type II: pitting, higher incubation GML
Mixed mode
• CM247LC has a high fraction of Al
Should provide good oxidation protection
Areas of incubation seen in Type I
However, performs poorly under hot corrosion conditions
(cf. Haynes 230, IN939, IN738LC)
Effect of low Cr content
Looking Forward
UK-US Project
• 20 systems being characterised
• Developing a greater understanding of the distribution
of corrosion damage around samples
Moving on the H2-IGCC (Framework 7) project
• Assess different combusted syngas environments
• Study state-of-the-art and advanced materials
systems
Acknowledgements
This work was carried out under the UK/US Collaboration on Advanced
Materials for Low Emission Power Plants programme of research.
UK activities funded by:
• the Department for Innovation, Universities & Skills
• the Department for Business, Enterprise and Regulatory Reform,
• Alstom Power and Siemens (UK).
US activities funded by:
• Department of Energy
• Siemens Power Generation Inc.
-700
-500
-300
-100
0 50 100
ΔG
M /
µm
Probability /%b)
300 hours700 hours1000 hours -120
-100
-80
-60
-40
-20
0
0 50 100
ΔG
M /
µm
Probability /%
300 hours700 hours1000 hours
c)
a) Mount
Damaged regions
Sample
Reference notch
755 °C
HfAl
Co
Cr
S
Ni
O
90 µm
955 °C
700 µm
Al
Co
Cr
S
Hf
Ni
O
SEM & EDX Results:Effect of Exposure Temperature (700 h, Test 3)
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