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NTPC Indian Power Stations Operation & Maintenance

Conference Sustainable Growth Strategies for

Fuel and Efficiency New Delhi, India February 2013

U.S. High Efficiency Strategies for Clean Coal Systems

Robert M. Purgert

President

www.energyinohio.org

U.S. Program for Advanced Ultrasupercritical (A-USC) Coal Fired Power PlantsR. Purgert, Energy Industries of OhioJ. Shingledecker Senior Project Manager, EPRI Fossil Materials & Repair ProgramP. Rawls, National Energy Technology LaboratoryS. Smith, Ohio Coal Developpment Office

NTPC-Indian Power Stations O&M Conference Sustainable Growth Strategies for Fuel and Efficiency

2© 2011 Electric Power Research Institute, Inc. All rights reserved.

Acknowledgements: U.S. Department of Energy (US DOE) / Ohio Coal Development Office (OCDO) A-USC Steam Boiler and Turbine Consortia

Federal – State – National LaboratoryNon Profit – For Profit

Cost Sharing Consortium

Federal – State – National LaboratoryNon Profit – For Profit

Cost Sharing Consortium

http://www.fwc.com/

http://www.alstom.com/

http://www.netl.doe.gov/main.html


Increasing Steam Temperature and Pressure Increases Thermal Efficiency and Decreases Emissions

Note: HHV Basis

“Least Regret” Strategy for CO2 Reduction“Least Regret” Strategy for CO2 Reduction


40

60

80

100

300

500

550 600 650 700 750 800

1100 1200 1300 1400

6

8

10

30

50

70

Stre

ss (M

Pa)

Average Temperature for Rupture in 100,000 hours (oC)

9-12Cr Creep-Strength Enhanced Ferritic Steels (Gr. 91, 92, 122)

Nickel-BasedAlloys

Std. 617CCA617

Inconel 740

Haynes 230

Advanced Austenitic Alloys (Super 304H, 347HFG, NF709, etc.)

Haynes 282

Average Temperature for Rupture in 100,000 hours (oF)

Stre

ss (k

si)

Materials Limit the Current Technology

°

Steels = USC 620°C (1150°F)

Solid Soln’ = A-USC ~700°C (1300°F)

Age Hardenable = A-USC 760°C (1400°F)

Minimum Desired

Strength at Application

Temperature


‘Aggressive’ goals for increased steam turbine temperatures are in-line with gas turbine improvements


Primary Technical Goals of US A-USC Materials Programs

• Materials Technology Evaluation• Focus on nickel-based alloys• Development of fabrication and joining technology for new alloys

• Unique Conditions for US Program Considerations• Higher-temperatures than European Program (760°C versus 700°C) means additional alloys are being evaluated

• Corrosion resistance for US coals• Data for ASME code acceptance of new materials• Phase II Boiler work includes Oxycombustion


Why 1400°F (760°C)? Best Approach to Achieving Good Economics

• Materials will limit the maximum achievable temperature• Economics will dictate the optimum temperature• For Example: a material suitable for 1400°F will have

economic advantages at 1300°F over other materials because components will have thinner walls

• Lower weight = lower material cost

• Thinner sections = easier to weld/erect

• Reduced thermal gradients = improved cycling

Nickel Price ($/ton) 2003-2008, courtesy Goodwin, UK

If you have to pay for nickel, make the most of it!If you have to pay for nickel, make the most of it!


U.S. DOE/OCDO: A-USC Steam Boiler Consortium

2: Material Properties

3: Steamside Oxidation

4: Fireside Corrosion

5: Welding

6: Fabricability

7: Coatings

8: Design Data & Rules(including Code

interface)

1: Conceptual Design

Develop the materials technology to fabricate and operate an A-USC steam boiler with

steam parameters up to 1400°F (760°C)

Develop the materials technology to fabricate and operate an A-USC steam boiler with

steam parameters up to 1400°F (760°C)

http://www.fwc.com/

http://www.alstom.com/



A-USC Steam Turbine Program: Phase I (complete)

• Scoping Studies – Downselect Materials• Key Issues

– Welded rotors materials– Non-welded rotor materials

Oxidation & SPE Studies

(Siemens, ALSTOM)Task 12.1

Review State of the Art and Identify Candidates for 760oC Application

(All)

Design & Econ Studies(ALSTOM)

Assistance (Siemens & GE Energy)Task 12. 5

Rotors, BucketsBolting

Task 12. 3

Non Welded Rotors (GE)Task 12. 3

Material property data characterization, microstructural and steam oxidation

studies(ORNL)

Castings (Siemens) Task 12. 4

MechanicalProperties (Siemens)

Task 12. 4

WeldedRotors (Siemens,

AlstomTask 12. 2

Mechanical Properties of

Materials (GE)Task 12. 3

Weldability Studies(Siemens, ALSTOM)

Task 12. 2

Mechanical Properties(Siemens,ALSTOM)

Task 12. 2

– Air Casting– Erosion resistance– Oxidation resistance



DOE/OCDO A-USC Steam Turbine Consortium Phase II

• Selected Materials from Phase I• Tasks

– 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



Approach: Address Key Technical Challenges for Materials & Components

• A-USC Boiler– Material selection based on strength & stability– Fireside corrosion– Weldability– Fabrication

• A-USC Turbine– Materials selection based on short & long-term strength,

stability, fatigue, and processing characteristics– Erosion and oxidation of blade materials and coatings– Castings– Welded rotors


Boiler materials selection based on strength and stability

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• Codes & Standards Interface

• Long-term weldment strength

• 40,000 hr + testing

• Vendor Discussions/Literature Search

• Materials Selection

• Procurement of Materials (7 alloys)

• Initial creep testing (10,000hr)

• Microstructure & Aging Studies

• Long-term strength

• Fabrication Effects

• Weldment behavior

• Testing for code case

Rupture Failure Map

SEM Image


Materials Selection for A-USC Alloys (Boiler Superheater/Reheater Tubing Strength)

A-USC Technology Requires Nickel-

Based Alloys

A-USC Technology Requires Nickel-

Based Alloys

Today’s Technology Limited by Steels

Today’s Technology Limited by Steels


Successes

• Materials have been identified with the requisite strength for an A-USC boiler with steam temperature up to 1400°F (760°F)

• Testing has eliminated certain alloys• A code case request has been submitted based on the

data produced by the program for Inconel 740• Some very long-term tests continue to add confidence to

life predictions• Testing of a new material (Haynes 282) has started


Fireside Corrosion 3 phase approach

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• 2nd Steam cooled loop installation, operation & analysis

• Oxycombustion effects

• Laboratory Studies (3 Coals, 3 WW Temps, 3 SH/RH Temps)

• Steam-cooled loops

•Most realistic environment

•High sulfur coal (aggressive)

• Air cooled probes

•Alloys and coatings selected from lab trials

•3 host site with 2 probes each

Test Loop Fabrication

Test Loop after

exposure

Procure - Test -Analysis

Fabricate - Operate -Analysis

Air cooled probe (cleaned)

Exposure

(site 1&2) (site3)

Analysis (all sites)

Fabricate 2nd loop


Successes: Air-cooled probes

Cleaned surface of an air-cooled probe exposed for 2 years in a coal-fired boiler at A-USC temperatures

Inconel 740 shows lower wastage than a high chromium cladding (50/50), a 23% Cr wrought alloy (HR6W), and weld overlays (WO)

Inconel 740 shows lower wastage than a high chromium cladding (50/50), a 23% Cr wrought alloy (HR6W), and weld overlays (WO)


Successes (cont.)

• An extensive laboratory test program has been completed on a myriad of alloys, coatings, and weld overlays to aid in materials selection for fireside corrosion

• Six air-cooled probes have been deployed and tested in three boiler burning different fuels

• The air-cooled probes showed Inconel 740 to perform as well or better than any other monolithic material and even outperform weld overlays in some instances

• A steam-cooled loop was fabricated and operated in a boiler above 1300°F/700°C (steam temperature) providing realistic data on a select number of alloys and coating. Again Inconel 740 performed very well despite the highly corrosive conditions.

• A second steam loop is under construction

Overall, the corrosion probes and loops have shown that alloys can withstand the corrosion environment of an A-USC boiler with

successive tests adding confidence for material selection

Overall, the corrosion probes and loops have shown that alloys can withstand the corrosion environment of an A-USC boiler with

successive tests adding confidence for material selection


Weldability

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• Additional mechanical property testing of welds

• Report on dissimilar metal welds

• Repair welding

• Welding

•7 alloys, multiple processes, thin & thick section

•Over 20 combinations qualified

•Some processes eliminated

•New learning: modified weld metal chemistries, different fluxes, process selection, etc.

Thick section success:

H230, CCA617

• Inconel 740

• Tube-to-tube successfully welded

• For thick section an extensive welding development program was needed

• Process is now repeatable

Initial welding

(cracking)EWI

StudyCreep Testing

Special Metals R&D

New Heats Produced

Testing

Modified Heats

Successful

Qualification

Final Optimized

ChemistrySave12 R&D

DMW

w/P87

Repair

Welding


Successes

Original Inconel 740 weld trials (Liquation cracking in heat affected zone)

Today: Repeatable 3” (75mm) thick Inconel 740 welds without cracking

Consortium Research

Consortium research has demonstrated revolutionary progress in nickel-based alloy welding


Fabrication

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• Cold-work effects on creep properties and recrystallization

• Evaluation of fabrication processes for new alloys

•Bending, machining, swaging, forming

•Cold work and recrystallization

•Testing of tube bends to evaluate cold-work limits

Basic fabrication

processes • Demonstration

articles were produced to showing multiple processes being put togetherDemonstration articles

Aging &

recrystallization Pressurized tube bend

tests and analysis


Successes

• No significant changes to fabrication techniques were required

• Initial R&D was used to make changes to ASME Section I Table PG-19 for H230 & 617

• Initial tests on Inconel 740 led to additional phase 2 work (ongoing) on cold-work effects on creep (how the bends will perform in service)


Materials selection for turbine rotors, discs, and blades

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• Additional steam-turbine specific testing

• Longer-term data

• Properties of large forgings

• Phase 1 – Initial material selection

•Extensive literature search, thermodynamic simulation, review of boiler work

•Selected 5 alloys for mechanical property study including multiple heat-treatment conditions

•Standard product forms

•Mechanical properties: tensile, creep, fatigue

•Microstructural development

• Phase 2 – testing of best alloys

• Select top candidate alloy for each component

• Extensive testing including: hold- time effects and notch sensitivity

• Testing for longer times of larger forgings

Initiate longer-

term testingAlloy Selection

& ProcurementTesting & Analysis

Program Start

Program Start( )

0.10

1.00

10.00

100 1,000 10,000 100,000 1,000,000

Cycles to Initiation (Ni)

Tota

l Stra

in R

ange

(%)

Nimonic 105 - 760CHaynes 282 - 760C

Udimet 720 - 750CAlloy 617 - 750C


36

38

40

42

44

46

48

50

52

1 10 100

Stress (ksi)

LMP

(C =

20)

Waspaloy

IN 740

Udimet 720Li

Haynes 282

Nimonic 105

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200 1400 1600

Temperature (F)

Stre

ngth

(ksi

)

Haynes 282SA-0.2% YS

Haynes 282PA-0.2%YS

Haynes 282OV-0.2%YS

Tensile Strength

Initial Material Selection for A-USC Turbine: Behavior of HP/IP Rotor Alloys

( )

0.10

1.00

10.00

100 1,000 10,000 100,000 1,000,000

Cycles to Initiation (Ni)

Tota

l Stra

in R

ange

(%)

Nimonic 105 - 760CHaynes 282 - 760C

Udimet 720 - 750CAlloy 617 - 750C

Fatigue Behavior

Creep-Rupture0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 200 400 600 800 1000 1200 1400

Tim e (h)

Stra

in (%

)

H282-P e a k a ge d1450F, 32.5ksi1450F, 27.5ksiMicrostructure

Best Candidates:Nimonic 105Haynes 282Waspalloy

Best Candidates:Nimonic 105Haynes 282Waspalloy


Successes: 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

Source: R. Viswanathan, J. Shingledecker, J. Hawk, S. Goodstine. “Effect of Creep in Advanced Materials for Use in Ultrasupercritical Power Plants.” Proceedings: Creep & Fracture in High Temperature Components, 2nd ECCC Creep Conference, April 21-23, 2009, Zurich, Switzerland.” © 2009 DEStech Publications, Inc. 31-43

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

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


Erosion and Oxidation of Blade Materials and Coatings

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• Oxidation studies

•Oxidation rates/kinetics

•Scale morphology

•Internal penetration vs. oxide thickness

•Bare metals (substrates) and coatings

Cross-section of bare metal after steam exposure

Base metal

testing• Erosion Testing

• High-temperature erosion tests were conducted at 1400°F (760°C)

• Coating and substratesCoating

selection

Program Start

Testing &

Analysis

Coating

testing

Analysis


Successes

• Oxidation rates (both internal penetration and mass gain) of candidate bare metal substrates were acceptable based on laboratory studies

• 14 candidate erosion resistant coatings were identified for high-temperature erosion testing and steam oxidation testing– Erosion testing identified four coatings with best

performance– Oxidation testing showed unacceptable rates for some

coatings including the best erosion performing coating• Coating T400C (Tribaloy) performed well in both tests

suggesting its use for blading protection


Castings

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• Production of larger casting

• Longer-term testing of larger castings

• Weld repair of castings

• Phase 1 – National laboratory study

•Trial melts made of candidate wrought alloys

•Simulated slow cooling for large casting

•Developed new heat-treatment cycles

•Screening creep and tensile tests including orientation effects

•Microstructure

• Phase 2 – testing of best alloys

• Select top two candidate alloy castings

• Produce larger castings

• Mechanical property testing

• Weld repair of castings

Initiated larger

casting trialsLab-scale tria

l melts &

heat-treatment

Program Start

Program Start

Range of microstructures in a slow-cooled casting

Mechanical testing &

microstructure


Successes

• A casting sub-team of OEM and National Laboratories (ORNL & NETL) was formed to address potential issues with nickel-based casing/shells

• Seven trial alloys were cast• An innovative homogenization heat-treatment cycle was developed• Mechanical property testing identified the best performing alloys• Some alloys were eliminated due to lower strength or ductility

compared to the wrought alloy counterpart• Haynes 282, 263, and N105 were judged the

best alloys for casting and castability trials were performed

• Based on this work, the phase 2 work on castings has a good starting point for development of larger castings

Alloy 263 casting – fluidity trial


Welded rotor evaluation

2001 2002 2

003 2004 2

005 2006 2

007 2008 2

009 2010

• Produce large ring weld

• Non-destructive evaluation

• Mechanical property evaluation

• Phase 1 – Welded rotor concept

•Produce welded joints at desired thickness

•Heavy section 263-617-Steel

•Seal weld between nickel based alloys

•Inspection study

•Property testing

•Aging and toughness

studies to simulate service exposure

• Phase 2 – welded rotor

• Large ring weld in design thickness and diameter (2 welds planned)

• Weld inspection

• Mechanical property and aging evaluation

Planning

Program Start

Program Start

Welded rotor concept

Welding and

inspection trials

Aging, testing, &

analysis


Successes

• Successfully produced a thick-section 263-617-Ferritic Steel joint concept using traditional welding techniques.– Joint toughness was acceptable after

aging (simulated service exposure) • A second welded rotor configuration was

evaluated for Haynes 282 to Udimet 720Li. – Welding development was successful

and heat-treatment studies showed no evidence of strain age cracking after welding

– Non destructive evaluation capability of joint was verified

Trial I Trial II Trial III


A-USC R&D

• Current Boiler & Turbine Materials R&D– Effect of oxycombustion on materials– Improved weld/weldment performance– Code approval of new alloys– Long-term high-temperature material

property databases– Production of larger forgings– Casting R&D for nickel-based alloys

Air , Low O2 , High O2

• Path Forward– Supplier Development for full-

size forgings, extrusions, and castings

– Test facility Demo Plant


Comparative Benefits from Program: Piping Sizes for Two A-USC Conditions

4” (100mm)

Main Steam 5000psi (34.5MPa)

9.8” (248mm) I.D.

Hot Reheat 1060psi (7.3MPa)

18.4” (467mm) I.D.

1300°F/1300°F (700°C/700°C)

1350°F/1400°F (732°C/760°C)

u.s. high efficiency strategies for clean coal systems ...indianpowerstations.org/ips 2013...

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