Reliability of (New) Supercritical Power Plants

J. Shingledecker, Ph.D. Sr. Project Manager, EPRI Fossil Materials & Repair Program (P87)

J. Philips, Ph.D., J. Wheeldon EPRI Fossil Fleet for Tomorrow Program (P66)

K. Coleman EPRI Boiler Life and Availability Program (P63)

“Advanced Technologies & Best Practices for Supercritical Thermal Power Plants.” Partnership to Advance Clean Energy – Deployment

(PACE-D) Technical Assistance Program (U.S. AID) November 21-22, 2013: New Delhi, India

Reliability of (New) Supercritical Power Plants U.S. Experience

2 © 2013 Electric Power Research Institute, Inc. All rights reserved.

Outline

• Historic Steam Temperatures U.S. • Early Supercritical (SC) Pulverized Coal (PC) Experience • Current Performance of U.S. SC Fleet • Recent U.S. SC/Ultrasupercritical Power Plants • Outlook for future


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1900 ’10 ’20 ’30 ’40 ’50 ’60 ’70 ’80 ’90 2000 ’10 Year

Tem

pera

ture

, Deg

rees

F

Tem

pera

ture

, Deg

rees

C

Eddystone 1

Philo 6

History of Steam Conditions for Fossil Fired Power Plants (U.S.)

• During 1st 60 years of the 20th century, steam turbine temperatures rose from 500°F to 1200°F – Thermal efficiency rose

from 4% to 40% (HHV) • Eddystone experienced

several materials issues – Derated from 1200°F to

1140°F • No significant improvements

in steam temperature for 50+ years

Maximum Steam Turbine Inlet Temperature History


Initial SC Experience (Eddystone) led to reduced steam parameters – modest improvements have followed


U.S. Fleet Efficiency (circa 2008)

SC-PC Powerplants have higher efficiency

Sub. Critical*(600-1600 psig)

Sub. Critical**(1800-2600 psig)

Super. Critical(3334+ psig)

20

30

40

Effi

cien

cy (%

) - U

.S. P

lant

s (2

008)

Average Efficiency (Bit) Average Efficiency (Subbit) 90th Percentile (Bit.) 90th Percentile (Subbit.)

* < 200MW** >200MWAdapted from: Improving the Efficiency of Coal-Fired Power Plants for

Near Term Greenhouse Gas Emissions Reductions, DOE/NETL-2010/1411


Early Supercritical (SC) Experience (U.S.)

• Nomenclature: – EAF = Equivalent Availability Factor – EFOR = Equivalent Forced Outage Rate

• Factors affecting performance:

– 1960’s-70s aggressive goals (Eddystone) conservative designs

– Economic pressures operations and maintenance – Scale-up of unit sizes growing pains – Boiler designs: Pressurized draft balanced draft


Improved Design Dramatically Improved SC Plant Availability

Adapted from: B. Slettehaugh et al. “Integrated Gasification Combined Cycle (IGCC) Versus Supercritical Pulverized Coal (PC) for Power Generation from Coal,” COAL-GEN 2005

1st Gen, 1st 5yrs

2nd Gen, Pressurized,

Pre-Conversion

2nd Gen, Pressurized,

Post-Converstion

2nd Gen, Balanced Draft

0

20

40

60

80P

erce

nt

Plant Description

EAF EFOR

Supercritical (SC) PC Plant Availability Improvements


U.S. SC-PC Plants have the same availability today as subcritical plants

Adapted from: B. Slettehaugh et al. “Integrated Gasification Combined Cycle (IGCC) Versus Supercritical Pulverized Coal (PC) for Power Generation from Coal,” COAL-GEN 2005

EAF for PC Units Larger than 375 MW (5 year period ending 1999)

# of Units Mean Top 25% Subcritical (375-525MW)

90 81.8 >88.3

Supercritical (SC)

102 82.0 >85.9

*Based on NERC GADS Data


Some Recent SC and USC PC Plants in Service in USA and Canada

Location Power Producer and Plant Name

Net output MW

Fuel Startup year

Main steam temperature,

ºF

Boiler vendor

Alberta, Edmonton EPCOR/TransAlta, Genesee Unit 3

450 Sub-bit 2005 1058 SC PC

Hitachi

Arkansas South West Electric Power, Turk Plant

600 PRB 2013 1112 USC PC

B&W

Colorado, Pueblo

Xcel Energy, Comanche Unit 3

750 PRB 2009 1055 SC PC

Alstom

Illinois, Lively Grove

Peabody Energy, Prairie State Energy Campus Units 1 and 2

2 x 750 Bit 2011/12 1055 SC PC

B&W

Iowa, Council Bluffs

MidAmerican, Walter Scott Unit 4

850 PRB 2007 1057 SC PC

Hitachi

Kentucky, near Louisville

LG&E-KU, Trimble County Unit 2

750 Bit. 2010 1082 SC PC

Doosan Babcock


Some Recent SC and USC PC Plants in Service in USA and Canada

Location Power Producer and Plant Name

Net output MW

Fuel Startup year

Main steam temperature,

ºF

Boiler vendor

Missouri, Weston

Kansas City Power& Light, Iatan Unit 2

850 PRB 2010 1085 SC PC

Alstom

Texas, near Bremond

Luminant, Oak Grove Units 1 & 2

2 x 800 Lignite 2009 1055 SC PC

Alstom/B&W

West Virginia, near Morgantown

GenPower, Longview Plant

700 Bit 2011 1056 SC PC

Foster Wheeler

Wisconsin, Oak Creek

We Energies, Elm Road Units 1 and 2

2 x 600 Bit 2009/10 1055 SC PC

Hitachi

Wisconsin, Wausau

Wisconsin Public Service, Weston Unit 4

500 PRB 2008 1085 SC PC

B&W

Bit. is bituminous coal B&W is Babcock & Wilcox PRB is Powder River Basin sub-bituminous coal

PC is pulverized coal Sub bit is sub-bituminous coal SC is supercritical

USC is ultra-supercritical USC is defined arbitrarily as temperatures above 1100ºF


In last 8 years: ~13GW of SC/USC PC plants have entered service in North America

30yr old mothballed


Innovations for today’s SC-PCs

• Higher efficiencies through higher steam parameters – Higher strength and

corrosion resistant materials

• Environmental controls

Temperature has a greater effect compared to pressure for efficiency


Early-life challenges in new SC/USC-PC Plants

Exfoliation Blockage

Creep-Strength Enhanced Ferritic (CSEF) Steel Erection and Fabrication

Metallic Wet FGD Corrosion

Stress Corrosion Cracking (SCC) in waterwall panels


Some Recent (U.S.) Powerplants Utilizing Advanced Stainless Steels Location Power Producer and

Plant Name Net

output MW

Fuel Startup year

Main steam temperature, ºF

Boiler vendor

Advanced Stainless

Steels

Arkansas South West Electric Power, Turk Plant

600 PRB 2013 1112 USC PC B&W 347HFG

Colorado, Pueblo

Xcel Energy, Comanche Unit 3

750 PRB 2009 1055 SC PC Alstom Super 304H

Kentucky, near Louisville

E.ON USA, Trimble County Unit 2

750 Bit. 2010 1082 SC PC Doosan Babcock

310HCbN (HR3C)

Missouri

Kansas City Power& Light, Iatan Unit 2

850 PRB 2010 1085 SC PC Alstom Super 304H

Wisconsin, Oak Creek

We Energies, Elm Road Units 1 & 2

2 x 600

Bit 2009/10 1055 SC PC Hitachi 310HCbN (HR3C)

Wisconsin, Wausau

Wisconsin Public Service, Weston Unit 4

500 PRB 2008 1085 SC PC B&W 347HFG (replacement)

Bit. is bituminous coal B&W is Babcock & Wilcox PRB is Powder River Basin sub-bituminous coal

PC is pulverized coal Sub bit is sub-bituminous coal SC is supercritical

USC is ultra-supercritical USC is defined arbitrarily as temperatures above 1100ºF


Damage has been observed from exfoliation of steam-grown oxides

347H superheater blocked by exfoliated oxides

Drain Line Erosion

Exfoliated Oxide Flakes


Best practices can avoid or manage steam-grown oxide exfoliation

Rapid Inspection for Exfoliation with

LFET probe

Inner diameter shot-peening can be used to effectively eliminate

tube blockages from steam-grown oxides (EPRI Report 1024027)

As-received surface = oxidation & exfoliation

Peened surface =

thin adherent scales

650C – 17bar Steam


Innovations in New USC Power Plants: AEP John W. Turk Unit 1

• Failures in Dissimilar Metal Welds (DMWs) have challenged the operation of SC powerplants

• EPRI Developed a new filler metal (EPRI P87) to eliminate the failure mechanisms in DMWs

• J.W. Turk has 4418 DMWs - 1215 have design temperatures of 1120- 1150°F (604-620°C)

• EPRI P87 was chosen for the most demanding temperature applications

347HFG-P87-T91 DMW Joint


Proper Implementation of CSEF Steels (Gr. 91/92) is crucial to good SC/USC Performance

Poor Casting Quality

Improper Welding & Design

Specification Guidance that Goes

‘Beyond the Code”

User-Friendly Tools

Poor Field Heat-Treatment resulting in excessive oxidation

and overtempering


Corrosion in Wet Flue Gas Desulfurization (FGD) Systems

Through-wall vessel leaks in 11months of operation (Duplex Alloy 2205)

Mitigation Options have been implemented on New Units: Potential

Adjustment Protection = no corrosion!

Corrosion in Immersion Zone

Forced Oxidation Wet FGD Schematic


Cracking in T23 waterwall panels Similar issues in China and Europe (T24)

• High-restraint conditions: waterwalls, attachments, roof tubes

• Reheat cracking • Stress corrosion cracking:

– during commissioning – Significant number (~1000) of

failures, rework required • Hydrogen induced cracking

– Poor fabrication practice

Examples of Cracking observed early life in T23/24

EPRI Welding Guidelines & Current Research on SCC

includes best practices for T23


Latest USC Power Plant in USA (2012) • SWEPCO’s (American Electric

Power) 665-MWg (630-MWnet) Turk Plant near Hope, Arkansas – PRB Coal – B&W Boiler/Alstom Turbine – 251bar/602°C/610°C (3640psia/1115°F/1130°F) – Projected Heat Rate: 8700 Btu/kWh (39.2% HHV)

• Materials: – SH/RH Tubes: 347H, 347HFG (shot peened) – Waterwall: T12 – Headers & Piping: Gr. 92 and 91

Source: AEP


Project Milestones

• Project announced Aug 9, 2006 • Received permit to install Nov. 5, 2008 • EPC full notice to proceed Dec. 8, 2008 • First coal fire Oct. 27, 2012 • Initial generator synch Nov. 8, 2012 • Commercial Operation Dec. 20, 2012 • Performance Tests Feb. 11 -13, 2013


U.S. SC/USC Plant Experience

• New materials are being utilized in SC/USC construction • ‘Early-life’ issues can be traced to improper use/selection of

materials • The experience and concurrent EPRI research can be used

to mitigate and/or eliminate these potential failure modes – Proper use of CSEF steels using EPRI guidelines – Proper selection of materials and alternatives for wet

FGDS – Proper fabrication and commissioning practices for

T23/24 – Procurement guidance for advanced stainless steels and

weld metals for dissimilar metal welds


A final word

Sub. Critical*(600-1600 psig)

Sub. Critical**(1800-2600 psig)

Super. Critical(3334+ psig)

20

30

40

Effi

cien

cy (%

) - U

.S. P

lant

s

Average Efficiency (Bit) Average Efficiency (Subbit) 90th Percentile (Bit.) 90th Percentile (Subbit.) New Supercrtical Plants (est.)

* < 200MW** >200MW2008 data from: Improving the Efficiency of Coal-Fired Power Plants for

Near Term Greenhouse Gas Emissions Reductions, DOE/NETL-2010/1411

Estimated efficiency (HHV) for new U.S. SC/USC Plants

2-4% increase HHV = 5-10% Reduction in Fuel, emissions, etc.


Together…Shaping the Future of Electricity

Documents

Reliability of (New) Supercritical Power Plants