wed 1520 romanosky
DESCRIPTION
Parson TurbineTRANSCRIPT
8th Charles Parsons Turbine Conference (September 5-8, 2011)
U.S. Department of Energy/Fossil Energy Materials Research
Development for Power and Steam Turbines
8th Charles Parsons Turbine Conference
Robert Romanosky
Advanced Research Technology Manager
September 5-8, 2011
2
Power Turbine Program GoalsImproving IGCC Performance with CCS
• Develop advanced coal power systems capable of 45-50% efficiency, and offer near zero emissions with multi-product production (electricity and hydrogen)
– 2015 Contribution to Goals
• H2 turbine w/ 3 – 5 % pts. improvement in CC
• H2 Turbine IGCC with 2 ppm NOx (@15 % O2)
– 2020 Commercial Demonstration of Advanced H2 Turbine in Coal Based IGCC with CCS
3
Overview of the Advanced
Power Turbine Materials Program
Key research Areas
• Novel coatings for unique “Thermal Barrier Coating” (TBC) bond
coat architecture
• Bond coats and rare-earth element effects
• Novel bond coats systems and the development of diffusional
barrier coatingsPhoto courtesy of N. Padture
4
Novel TBCs
• Novel TBCs are required for:
– Combustors
– Airfoils
– Shrouds
• APS or HVOF
• Efforts underway to:
– Develop reduced-cost diffusion bond coat (BC) systems
– Develop diffusion barrier coating (DBC) systems
– Investigate multiple compositions.
– Conduct applied microstructural research with a science focus.
Photo courtesy of S. Sampath –Stonybrook
5
Novel TBCs - Composition
TBC compositions of interest include:
1. Stabilized Zirconia
– lack thermal stability above 1400°C
– High-purity important
2. La- & Gd- Zirconate Pyrochlores
– Resistant to ash deposition w/ high T stability
– Less erosion resistant
– TGO interactions suggest multi-layer structure required
3. Stabilized Hafnia
– High melting point suggests good thermal stability
– Cost could be an issue
• Additional toughness for Foreign Object Damage resistance desirable
6
Novel TBCs - Microstructure
• Thermal and mechanical properties heavily influenced by microstructural features
• Stonybrook developing process maps to correlate processing conditions to thermal conductivity & elastic modulus
• Fundamental science improves component reliability by increasing part-to-part consistency.
TBC MicrostructuralFeatures
Figures courtesy of S. Sampath –Stonybrook
7
Bond Coats
• Oxidation-resistant bond coats needed to protect expensive substrates.
• Thermally-grown oxides must be adherent
• Focused on MCrAlY coatings applied via APS or HVOF
Efforts Underway
• Effects of rare-earths in CMSX-4 superalloys were quantified via thermal cycling at 1100°C
• MCrAlY bond coatings with Hf and Si additions showed longer lifetimes compared to MCrAlY
• La additions are also being studied
• Studies being conducted on moisture effects on TBC coatings
8
Bond Coats – Moisture
• Effects of moisture being quantified at lab scale
– Pt-based diffusion and aluminides complete
– MCrAlY coatings underway• Unclear if issue or not
• Evidence for mechanism building
– Rumpling appears to play some role in some cases
– Not clear if mechanism is same in MCrAlY coatings
• Working on mitigation strategyFigures courtesy of B. Pint –ORNL
Thermal Cycle Lifetimes
Bond Coat Roughness
9
“Advanced” Ultra Supercritical Power Plant Operating up to 5,000 psi and 1,400 °F
• Ultrasupercritical (USC) DOE goal for higher efficiency and much lower emissions, materials capable of:
– 760 °C (1400 °F)
– 5,000 psi
– Oxygen firing
• Plant efficiency can be improved to 45-47 Ultrasupercritical (USC)
• CO2 Emissions are reduced by 15 to 22%
• Lower balance of plant cost means smaller coal handling and pollution controls for the same net plant output
• Meeting these targets requires:
– The use of new materials
– Novel uses of existing materials
160015001400130012001100100090040
42
44
46
48
Temperature (°F)
Pla
nt
Th
erm
al E
ffic
ien
cy (%
)
3500 psi
5500 psi
Birks and Ruth
10
A-USC Steam Turbine Materials ProgramResearch Areas
– Materials for non-Welded Rotors, Buckets and Bolting
– Coating for Steam Oxidation and Solid Particle Erosion
Resistance
– Energy Erosion Resistant Coatings Study for USC Steam
Turbine 760 °C Department of Energy Initiative
– Process Development for Welded Rotors
– Cast Ni-based Superalloys for Turbine Casing Application
11
Turbine Material Candidate List
• Assessed mechanical and other physical properties,
processing and manufacturing capability of 25
candidate alloys
– Five alloys were identified as candidate materials for
a rotor forging:
1. Nimonic ® 105 (N105)
2. Haynes 282 (H282)
3. Udimet 720Li (U720Li) (Not Tested)
4. Inconel 740 (IN740)
5. Waspaloy
12
Temperature Capability - HP/IP Rotor Alloys
700
800
900
1000
1100
1200
1300
1400
1500
0 5,000 10,000 15,000 20,000 25,000 30,000
Operating Stress (psi)
Tem
pera
ture
Capability (
Deg F
)
HP Typical
IP Typical
CrMoV
Cost E
IN625HT
IN718
U720Li
IN901
IN740
H282
N105
Initial Material Selection for A-USC TurbineTemperature Capability for HP/IP Rotor Alloys
760°C
Best Candidates: Nimonic 105, Haynes 282,
and Waspalloy (not shown)
13
Large Forgings Research Requires an Understanding
of Microstructure & Properties as a Function of Heat-
Treatment
50 nm
Solution Annealed OV = PA + 250h @ 775°C
50 nm
PA = SA + 8h @ 790°C
Studies on Haynes 282:
• Creep-rupture strength was relatively insensitive to heat-treatment
• Detailed microstructural studies on gamma prime precipitates after heat-
treatment and creep were conducted
• Both mechanical property data and microstructure studies suggest the alloy
has a large processing window making it attractive for steam turbine
forgings
14
Oxidation and Erosion
Laboratory Screening
• Short- and Long-Term Steam oxidation testing of candidate
nickel based alloys for A-USC steam turbine components and
candidate coatings for SPE resistance.
– Screening tests in a thermo-gravimetric analyzer
– 10,000 hours in steam at atmospheric pressure and
temperatures of 700, 760 and 800°C
• Substrate alloys Udimet 720LI, Waspaloy and 740 were the
most resistant to steam oxidation
Cross-sections of base metals
after steam oxidation
experiments
CCA 617 Haynes 230 Haynes 282
15
Coatings
• Steam Oxidation Resistance (14 coatings tested)
– Stellite 6B, Tribaloy, T-400C and CrC-NiCr were the most
resistant
• SPE Resistance
– Erosion testing on 12 coatings using the University of Cincinnati
test rig.
– Silica sand and magnetite used as the erodent materials for this
testing.
– A limited amount of testing was done with alumina as well.
– The top 4 coatings ranked according to their erosion rates and
volume losses were:
1. Moly-Boride – Cobalt Chromium
2. Zircoat
3. T400C (Tribaloy)
4. Conformaclad WC
16
Process Development for Welded Rotors I
• Assess the weldability of Nimonic
263, a typical precipitation-
strengthened, wrought nickel-base
alloy which is a candidate for higher-
temperature rotor applications
• Develop welding procedures for
joining this alloy to Inconel 617 in
thick sections.
• Assess the effect of long-term
(10,000 hr) simulated service
exposure at 725°C on the
microstructure, hardness, tensile
properties, and impact strength of the
weld
Results:
There was little change in microstructure, hardness, or tensile properties of
the thick-section weldment, but the impact strength was reduced in all
microstructural zones of the weld. However, all zones had impact strengths
sufficient to demonstrate adequate toughness, even after elevated-
temperature exposure
17
Process Development for Welded Rotors II
• The goal of this task was an electron beam welding feasibility
study of Udimet 720Li to Haynes 282, and Haynes 282 to itself
and to Inconel 617
– welding trials were completed on simplified weld samples (small, flat
samples) not entire rotors, as a feasibility study
– Weld process selection was electron beam welding due to weld
penetration requirement, rigidity of post-weld component, base alloy
selections, weld quality requirements and current available technologies
which could accommodate the production size of the component.
The final results of all three alloy
combinations were favorable.It can be concluded that all three weld
combinations attained favorable weld
results via visual, ultrasonic immersion
testing and metallographic evaluations
on small, flat samples. Additional work
is required for a full assessment of
manufacturability and fitness for service.
18
Welded Rotor Concept Evaluation
• Various joint configurations were
successfully demonstrated
– Alloy 263 to 617
– Haynes 282 to Udimet 720Li
• Evaluation: tensile, creep-rupture,
toughness, and aging response
Trial I Trial II Trial III
Udimet 720Li Trials
Aging &
Toughness
Studies
19
Materials for Non-Welded Rotors, Buckets,
and Bolting
• Identify suitable materials that can be made into a
single piece rotor or the highest temperature portion
of a mechanically coupled rotor, buckets and bolting
operating in a steam turbine with an inlet
temperature of 760°C (1400°F)
• Evaluation based on Rupture Strength, Yield
Strength, Fracture Toughness
• Materials selected:
– Alloys 617 and 625 for turbine castings and rotor
forgings
– Alloys 718 and 263 for rotor forgings
– Alloys 105 and Waspaloy for blades and bolting
20
Castings
• Casting are required for turbine
shells, valve bodies, tees, etc.
• Traditionally air cast
• Screening study conducted by
Oak Ridge National Laboratory
and the National Energy
Technology Laboratory
• Lab-scale castings, mechanical properties, microstructure, and heat-treatment were examined
• Cast Nimonic 105 and HR282 have much better creep
resistance and rupture ductility than IN 740.
• Alloy 263 has much better strength and creep-rupture
resistance than the other solid-solution cast alloys
21
Steam Turbine Phase II Work
• Tasks Using Selected Materials from Phase I:
– Rotor/Disc Testing (near full-size forgings)
– Blade/Airfoil Alloy Testing
– Valve Internals Alloy Testing
– Rotor Alloy Welding and Characterization
– Cast Casing Alloy Testing
– Casing Welding and Repair
22
NETLwww.netl.doe.gov
Contact Information
Office of Fossil Energywww.fe.doe.gov
Robert R. Romanosky
304-285-4721
Patricia Rawls
412-386-5882
Richard Dennis
304-285-4515