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Fireside Corrosion in Oxy and Air-FiringCombustion Environments

Steven C. Kung

IEAGHG Oxy Combustion WorkshopJanuary 26, 2011

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Objectives

• Perform air and oxy-coal combustion to produce realistic fireside corrosion conditions.

• Measure the gas compositions and deposit chemistry generated from coal combustion.

• Conduct laboratory corrosion tests.• Compare corrosion performance by alloy, coal,

and combustion mode.

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Approach• Online measurement of gas compositions in

pilot-scale testing facility using FTIR and GC.• Collect and analyze deposit samples from

cooled probes.• Design of 1000-hour laboratory test conditions

based on information measured from pilot-scale testing.

• Perform 1000-hour fireside corrosion simulations in laboratory.

• Conduct long-term field test in FutureGen 2.0 plant.

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Warm Recycle Oxy Combustion Pilot-Scale Testing Facility

Combustor

CO2

Vaporizer

Coal Feeder

O2

Evaporator

Wat

er Ja

cket

Wet Bottom

Ash Collector

Cyclone

Ash Drum

Heat Exchanger

Low T Fan

Scrubber

To Stack

High T Fan

Room Air

Variable speed fan

Compressed Air

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Gas and Deposit Sampling in Pilot-Scale Combustor

Gas Sampling• Outer jacket water cooled.• Inner tube heated to 180oC.• Heated line (180oC) from

BFR to gas analyzers.

Deposit Sampling• Water-cooled probe in burner

zone.• Air-cooled probe in oxidizing

zone.

0

Gas Sample Probe

37.5 75

Deposit Collection Probes

Metal T: 400-600oC

Metal T: 600-800oC

Burner

Exit

0 cm

265 cm

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Online Sampling Train for In-Furnace Gas Measurement

Flue Gas

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Chemistry of Four U.S. Coals Proximate Analysis,As Received

IL #6 Galatia

WY PRB

OH Mahoning

OH Gatling

Moisture 3.68 21.23 2.22 3.77Ash 10.45 5.53 9.92 11.34Vol. Matter 33.70 33.76 40.79 40.73Fixed Carbon 52.17 39.48 47.07 44.16

Ultimate AnalysisAs Received

Moisture (%) 3.68 21.23 2.22 3.77Hydrogen (%) 3.14 2.06 4.18 4.07Carbon (%) 67.66 54.39 74.67 67.11Nitrogen (%) 0.95 0.86 0.93 0.94Sulfur (%) 2.96 0.26 1.96 4.31Oxygen (%) 11.16 15.67 6.12 8.46Ash (%) 10.45 5.53 9.92 11.34Chloride (%) (dry basis) 0.283 0.001 0.199 0.039Heating Value (Btu/lb) 12,464 9,479 13,404 12,191

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Comparison of Gas Species Concentrations(at Superheater)

By Combustion Calculation By Online Measurement

CO2 H2O SO2 CO2 H2O* SO2†

PRB (0.26% S)75% 22% 793 ppm 73% 26% 520 ppm

Gatling (4.31% S)77% 18% 10,640 ppm 76% 19% 9,011 ppm

Oxy-combustion of PRB and Gatling coals with warm-recycle at S.R. = 1.15

* Further FTIR calibration needed for higher H2O concentrations.† About 65% and 85% coal sulfur present in the gas phase, respectively.

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Laboratory Fireside Corrosion Testing Facility

Three sets of fireside corrosion testing facility available at B&W.

Each capable of lower and upper furnace simulations.

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Laboratory Test Coupon Arrangement

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Laboratory Test Conditions for PRB CoalAir Firing, 1300oF (700oC), 1000 hours

Oxide Wt.%

Al2O3 17.9

SiO2 31.8

CaO 21.2

Fe2O3 5.1

KOH 0.8

TiO2 1.2

MgSiO3 4.2

MgSO4 12.3

Na2SO4 5.5

Species Vol.%

CO2 17

O2 2.9

SO2 0.02

H2O 12

N2 bal.

304HSuper 304H310HCbN

230347HFG

347H72 WO52 WO

671 740617120

800H

Mixed Gas CompositionSimulated

Deposit Composition Alloys Tested

Gas and deposit compositions determined from pilot-scale testing.

Oxide Wt.%

Al2SiO5 8.0

Ca3Al2Si3O12 57.0

Fe2O3 4.1

KFeO2 1.6

MgSiO3 4.2

SiO2 6.1

TiO2 1.2

MgSO4 12.3

Na2SO4 5.5

Measured Equilibrium Deposit Composition

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Laboratory Test Conditions for PRB CoalOxy Firing , 1300oF (700oC), 1000 hours

Oxide Wt.%

Al2O3 17.9

SiO2 31.8

CaO 21.2

Fe2O3 5.1

KOH 0.8

TiO2 1.2

MgSiO3 4.2

MgSO4 12.3

Na2SO4 5.5

Species Vol.%

CO2 62

O2 2.9

SO2 0.2

H2O 26.4

Ar 2.5

N2 6.0

304HSuper 304H310HCbN

230347HFG

347H72 WO52 WO

671 740617120

800H

Mixed Gas CompositionSimulated

Deposit Composition Alloys Tested

(1) Gas composition determined from combustion calculations (worse case). (2) Air-firing deposit composition used.

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Comparison of Gas CompositionsBetween Air and Oxy Firing

Gas SpeciesAir Firing(Measured)

Oxy Firing(Calculated)

vol.%

CO2 17 62

O2 2.9 2.9

SO2 0.02 0.2

H2O 12 26.4

Ar - 2.5

N2 68 6

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Alloys and Weld Overlays Evaluated304H S304H 310HCbN 230 347HFG 347H EN72 EN52 671 740 617 120 800H

Ni 11 8.73 19.97 59.5 11.98 10.42 47.2 56.3 50.7 49.45 53.2 37.3 32.7

Cr 18.83 18.68 25.61 21.31 18.4 17.67 >41.2 29.6 48.19 24.31 22.63 25.1 21.0

Fe Bal 67.6 Bal 1.25 Bal 68.4 10.6 12.2 0.078 1.02 0.76 34.7 Bal.

Mo 0.32 - 1.28 - 0.24 0.07 0.03 0.034 0.52 9.38 0.27 -

Co 0.14 - 0.14 - < 0.1 0.02 0.003 0.23 19.63 12.33 0.10 -

C 0.05 0.084 0.05 0.088 0.09 0.045 0.023 0.029 0.047 0.034 0.06 0.06 0.08

N 0.11 0.24 - - - - 0.20 -

B - - 0.005 - - - - 0.002 - 0.002 - -

Mn 1.8 0.8 1.18 0.51 1.46 1.84 0.11 0.29 - - 0.02 0.71 0.80

Si 0.45 0.14 0.36 0.45 0.41 0.44 0.16 0.2 0.018 0.45 0.15 0.48 0.59

Al - - - 0.44 - - 0.14 0.7 0.27 0.75 1.15 0.059 0.45

Ti - - - - - - 0.44 0.53 0.37 1.58 0.27 - 0.31

Nb - 0.52 0.47 0.053 - - 1.83 - 0.61 -

Nb+Ta - - - - 0.9 - 0.02 0.02 - - - - -

V - <0.1 - 0.011 - - 0.02 0.02 0.008 - - - -

W - - 14.93 - - ND ND 0.002 - - 0.10 -

Cu - 2.78 - - - 0.35 0.03 0.02 0.002 0.05 - 0.11

P 0.01 - 0.015 - 0.027 0.026 - - - - - - -

S 0.013 - - - 0.001 0.003 - - - - 0.001 - <0.002

Other - - - - - - - 0.058 - - - - -

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Comparison of 1000-Hour Laboratory Test ResultsPRB, 1300oF (700oC), 1000 Hours

0

10

20

30

40

50

60

304H

S304

H

310H

CbN

230

347H

FG

347H

72 W

O*

52 W

O

671

740

617

120

800H

mpy

Air Firing

0

10

20

30

40

50

60

304H

S304

H

310H

CbN

230

347H

FG

347H

72 W

O*

52 W

O

671

740

617

120

800H

mpy

Oxy Firing

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FutureGen 2.0 ProjectCommercial Scale Demonstration

B&W/AL have tested oxy-coal combustion at 10 MWe plant scale (CEDF) and will demonstrate the technology at commercial scale.FG 2.0 will:• Prove safety and control.• Develop cost basis for scale up to large commercial plants - 500 to

800 MWe• Prove operability and reliability of the integrated process - Boiler

Island, Air Separation Unit and Compression & Purification Unit• Provide performance and emissions data for future commercial

guarantees.• Provide operating and maintenance experience for future

commercial plants.

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FutureGen 2.0 Oxycombustion Carbon Capture Plant

Meredosia Plant • Meredosia, IL: Owned/operated by

Ameren Energy Resources (AER).• Repower 200 MWe Unit 4 steam

turbine.• Purpose-built Oxy-PC boiler.• Illinois Coal, PRB, or PRB blends.

Project Structure• Capture – (AER), teamed with B&W

and Air Liquide.• Transport & Storage – FutureGen

Alliance (FGA).

Project Timeline • Awarded Sept. 30, 2010.• Phased approach to develop project.• Commission by April 30, 2016.• Test Period May 2016 – Dec. 31, 2018.

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Conclusions A comprehensive study on oxy combustion fireside corrosion is

conducted by B&W, which consists of pilot-scale, laboratory, and full-scale testing.

Online gas and deposit measurements being performed in a pilot-scale combustion facility burning four U.S. coals under air and oxy firing conditions.

Long-term fireside laboratory corrosion tests being conducted under conditions determined from pilot-scale testing.

Preliminary laboratory results on PRB under simulated conditions do not suggest rapid superheater corrosion.

Initial design of FutureGen 2.0 is underway.

Field tests to be performed in the commercial FutureGen 2.0 demonstration plant under oxy combustion.

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Questions?