7. Corrosion Abo

8/13/2019 7. Corrosion Abo

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Performance of superheater materials

in simulated oxy-fuel combustion

conditions at 650C

Modified from

EUROCORR 20114-8 Sept, Stockholm

D. Bankiewicz1, S. Tuurna2, P. Yrjas1, P. Pohjanne2

1bo Akademi University, Turku, Finland2VTT Research Centre, Tampere/Espoo, Finland


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2

Test plan

Conditions Test length (h) CO2 O2 H2O N2 (vol%)

Oxy-fuel 1 168 60 4 0 36

Oxy-fuel 2 168 60 4 10 26

Oxy-fuel 3 168, 500, 1000 60 4 30 6

66.19

66.7

43.64

51.98

18.3

18.6

23.56

26.1

11.7

11.6

24.08

19.46

5.3 2.83

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

TP347HFG

TP347HFG_1

Sanicro 25

HR3C

Fe Cr Ni W Cu


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Laboratory method for HT corrosion tests

1. Preparation of salts

2. Preparation of steel samples for the experiment

3. Tube furnace tests

4. Preparation of samples for SEM/EDXA

5. Analysis of SEM results





















0

50

100

150

200

250

0 500 1000 1500 2000 2500 3000 3500 4000Oxidelaye

rthickness[m]

Cross section [m]


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HR3C

Sanicro25

3

47HFG

0

20

40

60

80

100

168 h 500 h1000 h

Oxidelayer

thickness,m

Oxide layer thickness 347HFG after exposures in

60%CO2-30%H2O with CaCO3-CaSO4

- carburization of the material


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Carburization of 347HFG after exposure to

85CaCO3+ 15CaSO4, 650 C

60% CO2, 30% H2O


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No carburization of 347HFG after exposure to

CaSO4, 650 C

60% CO2, 30% H2O


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4. Tests in 60% CO2, 30% H2Owith pure CaSO4at 650 C

no measurable oxide layer was found on the samples no carburization

3. Tests in 60% CO2, 30% H2Owith 85 CaCO3+ 15 CaSO4at 650 C

measurable oxide layer just on 347HFG material clear carburization of 347HFG after 168, 500 and 1000 h exposures

Conclusions and wrap up of tests in high CO2

2. Tests in 60% CO2, 30% H2Owith no salt at 650 C

no measurable oxide layer was found on the samples no carburization oxide layer growth on 347HFG after longer exposures (500, 1000h)

1. Tests in 60% CO2, no H2O with no salt at 650 C

no measurable oxide layer was found on the samples

no carburization


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Is the lower resistance of 347HFG in high CO2atmosphere caused by water

vapor? Differences in 347HFG vs. 347HFG_1 performance?

347HFGvs. 347HFG_1

Molybdenum was reported to have a negative effect in water vapour. Mo can formhighly volatile hydroxyl what can increase the tendency of scale cracking and havean impeding effect on scale healing [1].

Here 347HFG 0.23Movs. 347HFG_1 0.04Mo

HR3C and Sanicro 25 no Mo and Cr content is > 20%

Generally lower resistance of 347HFG too low Cr content

[1] Schtze et al. Materials Research, Vol. 7. 1, 111-123, 2004

7. Corrosion Abo

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