3 Ageing and Corrosion of Steels in CO2 rich flue gases ...

Ageing and Corrosion ofAgeing and Corrosion of Steels in CO2 Rich Flue Gas2

Daniela Hünert, Gabriele Oder, Werner Österle, Romeo Saliwan-Neumann,, Wencke Schulz, Ingrid Urban & Axel Kranzmann*

Federal Institute for Materials Research and Testing, BAM,

Berlin, GermanyBerlin, Germany

*presenter

1st OXYFUEL COMBUSTION CONFERENCE, Cottbus 2009HT-Corrosion Team , BAM V.1

Tuesday, Sept. 08, 2009 1/35

Outline• Introduction

– Experimentspe e ts– Materials and Specimen– Test atmosphere p

• Results of the corrosion experiments• DiscussionDiscussion

– Phase formation– Influence of ashes

• Conclusions


Tuesday, Sept. 08, 2009 2/35

Introduction: Experiments

Two types of equipmentCorrosion of flat samples in a reactor: Pressure-oxidation-simulation-machinery:

high pressureForces

pambient pressure

Forces

S /G

Air (O2, N2)

Steam/Gas Steam/Gas


Tuesday, Sept. 08, 2009 3/35

PhD thesis D. Hünert

Pressure Oxidation


Pressure-Oxidation-Simulation-Test

2 independent furnaces

Water preheaterHot gas generator

P t lp

Tmax = 1300 °CPressure control

Specimen

Controlling

Condenser with

- gas velocity: 0.01 to 80 m/s- steam: up to 3000 m3/h

CO2 Gas recirculation


Tuesday, Sept. 08, 2009 4/35

Condenser withH2O-CO2-separation

p- pressure: 320 bar- temperature: 1300°C


100

Gas compositon against temperature, equilibrium with material surfaceM

ol

Tubeinlet H2

CO

10-6

M 10

10-16

CH4

T/°C100 600Pressure 80 bar

In the recycled gas CO will be concentrated because of low solubility in water.


Tuesday, Sept. 08, 2009 5/35

Materialsle

ntN

i-Equ

iva

Commercial steels: 13CrMo44, T24, T92, X20, DMV310NCr- Equivalent


Tuesday, Sept. 08, 2009 6/35

, , , ,Test materials: B, S1, S10

Introduction: Materials and Specimen

Two types of

Test in Reactor (ambient pressure)Coboid, 4 to 5 mm thickness20 mm edge length

Specimen Thermocouple positions

Gasinlet


Tuesday, Sept. 08, 2009 7/35

Total specimen length 900 mm Diameters up to 90 mm are possible

Introduction: Materials and Specimen

Total specimen length 900 mm. Diameters up to 90 mm are possible.

SamplingTemperature profile

tube lenght

Measured temperaturePolynomial function

The profile is established by gas flow and cooling at both


Tuesday, Sept. 08, 2009 8/35

endings of the specimen

Gas composition after boiler

Introduction: Test atmospheres

Gas composition after boilerTest rig rangeCO2: 50 - 53 %H2O: 19 - 35 %

Experimentelle Untersuchung der Schadstoffentstehung bei der Verbrennung im Oxyfuel-ProzessK. Mieske, Prof. A. Kather40. Kraftwerkstechnisches Kolloquium, 14.-15.10.2008, Dresden

N2: - 5 %O2: 5 - 11 %

Studie eines braunkohlegefeuerten 2470 t/h-Oxyfuel-DampferzeugersHellfritsch, S.; Kluger, F.; Bergins, C.39. Kraftwerkstechnisches Kolloquium, 11.-12.10.2007, Dresden

The combustion of dry lignite under Oxy-fuel process conditions in a 0.5 MWth test plant.Helge Kaß, Stephanie Tappe, Hans-Joachim Krautz,Physics Procedia 2008.

0.5 MWth cycloid fired test rig of the Chair of Powerplant technologies of the Brandenburgische Technische Universität Cottbus, H. Kaß, H.J. Krautz, Göteburg 2008


Tuesday, Sept. 08, 2009 9/35

http://en.wikipedia.org/wiki/File:Composition_comparison.JPG

Test MatrixBold -> performed experiments

Total pressure / bar

81

> performed experiments

31 4Syn. Air + 68CO2 + 28H2O31

70CO + 30 H O70CO2 + 29 H2O + 1 O2

3Syn. Air + 68CO2 + 28H2O + 1SO2

Temperature / °C

400 500 550 600 650

1 70CO2 + 30 H2OH2O (Only 1 bar)


Tuesday, Sept. 08, 2009 10/35

Temperature / C

The corrosion experiments aimed to answer:

- What are the basic corrosion reactions?

- Can the current steels work in oxyfuel atmospheres up to the same temperature regime than in conventional power plants?

- Will be the corrosion kinetic different in CO2 concentrations?

- Are unexpected limitations observable?


Tuesday, Sept. 08, 2009 11/35

1 bar 70 CO2 - 29 H2O - 1 O2

Results of corrosion experiments

1 bar, 70 CO2 29 H2O 1 O2


Tuesday, Sept. 08, 2009 12/35

Analysis by D.Hünert


T92 The different steels show a pressure dependence in scale thickness.

alloy B


Tuesday, Sept. 08, 2009 13/35

Analysis by D.Hünert


H2O-CO2 H2O-CO2-O2

Material Loss after 1000 h 30 bar atmosphere

ss /

µm

200

ckne

ss lo

s

100

Wal

l thi

c

50

The real material loss indicates the material loss of alloy B.The loss of DMV310 was below the 10 µm


Tuesday, Sept. 08, 2009 14/35

The loss of DMV310 was below the 10 µm.Analysis by W. Schulz

Material loss compared with scale thickness 30 bar


H2O-CO2-O2

Material loss compared with scale thickness 30 bar

2 2 2


Tuesday, Sept. 08, 2009 15/35

Total Scale thickness Analysis by W. Schulz


Flowing H2O-CO2-O2 1000 h, 1 barg

Carbon richThin hematiteMagnetite

T92Internal corrosionincreased C content

precipitates

T92T92

10 µm

increased C content10 µm

T92

alloy BT24

10 µm

Carbon richprecipitates

Internal corrosionincreased C content


Tuesday, Sept. 08, 2009 16/35

10 µm

precipitates10 µm

625°C 1000 has receivedSteel T92


)

625 C, 1000 has receivedSteel T92

a)

Growth of M26C6

Courtesy of Bruker Inc. LtD


Tuesday, Sept. 08, 2009 17/35

y


600°C13CrMo44 600 C13CrMo44oxide scale

FeOOH

80 bar13CrMo44

Fe3CX20CrMoV12-1(Cr, Fe)23C6

Perlite lamella

1 bar

steel oxide interface

T92, 550°C,1bar

T92, 600°C, 80bar

Th TEM l i d t t dThe TEM analysis demonstratedthe high carbon activity in CO2-H2O and CO2-H2O-O2 atmospheres. Carbide phases were Fe3C and M23C6


Tuesday, Sept. 08, 2009 18/35

Carbide phases were Fe3C and M23C6

and coke in the oxide scale.

H2O-CO2 1000 h H O CO O 1000 h


H2O CO2, 1000 h H2O-CO2-O2, 1000 h13CrMo44T24T92X20CrMoV 12-1alloy B

13CrMo44T24

30 bar

th /

µm

y T24T92X20CrMoV 12-1alloy B

atio

n de

pt

13CrMo44

80 bar

carb

uris

13CrMo44T92X20CrMoV 12-1alloy B


Tuesday, Sept. 08, 2009 19/35

temperature /°C temperature /°CAnalysis by D.Hünert

D l C i diti synth air only


Dual Corrosion condition synth. air only

H2O-CO2-O2 H, H2 O id ti i i t llO id ti i i ith2

CDruck

Air

Oxidation in air at all surfaces

Oxidation in air with Oxyfuel atmosphere at the opposite surface. su ace

The reaction at opposite surfaces is not independent ifsurfaces is not independent if C od H2 can diffuse.


Tuesday, Sept. 08, 2009 20/35

Lit.: D. Huenert, W. Schulz, A. Kranzmann: Corrosion behaviour of ferritic and martensitic power plant steels under conditions of dual atmospheres. Nace Conference Corrosion, 2009, Atlanta


Carburization of base material - dual conditionsH2O-CO2 (80 bar) / Air

steel alloy B, 600°C, 1000 hsteel T92, 600°C, 1000 h

air H O COair H2O-CO2


Tuesday, Sept. 08, 2009 21/35Analysis by D.Hünert

Steel S10: 11% Cr 500h/600°C


Steel S10: 11% Cr, 500h/600 C

Magn.

x 2.5

H2O - CO2 - synthetic air H2O - CO2 - synthetic air - SO2

Schliff 6084 Schliff 12615

region withhigh C content

H2O CO2 synthetic air

10 % CO22 % N2

H2O CO2 synthetic air SO2

100 ppm SO2

SO enhanced scale growth


Tuesday, Sept. 08, 2009 22/35

SO2 enhanced scale growthAnalysis by D.Hünert

Ash from lignite (Lausitz)

Results of corrosion analysis

Flue gas:28H2O-66CO2-5O2

g ( )Fe3O4, SiO2, Fe2O3,CaSO4, MgO, FeCO3 + residual carbon

Ash layer F it28H2O 66CO2 5O2plus SO3 SO2

NOx

Ash layerOxide scale Ferrite

CAmbient Air Carburisation

C

C

Alloy B Test ring corroded in the CEBRA b ti i BTU C ttb C diti 125 hcombustion rig, BTU Cottbus, Conditions: 125 h,

600 °C surface temperature(Air cooled corrosion probe). But take the kind of combustion into consideration.P f D I K t Di l I Fi d i

An ash layer might not change the principle reaction with carbon.


Tuesday, Sept. 08, 2009 23/35

Prof. Dr.-Ing. Krautz, Dipl.-Ing. Findeisen

Only CO2 or CO can cause the

carburisation.

Th d d i di hThe pressure dependence indicates that

CO2 or H2O or both can direct react at theCO2 or H2O or both can direct react at the

interface steel - oxide.


Tuesday, Sept. 08, 2009 24/35

Discussion: Corrosion reactions

Di i b F d CO aDirect reaction between Fe and CO2

Examples: 2Fe + CO2 2FeO + C2/3 Fe + CO2 1/2 Fe3O4 + C

K = ac

pCO2

/3 Fe + CO2 /2 Fe3O4 + C

Direct reaction between Fe and CO K = ac

pCOpCOExamples: 3/4Fe + CO 1/4Fe3O4 + C

2/3 Fe + CO 1/3 Fe2O3 + C

0 5

Direct reaction between Fe and H2O

Example: 3/4Fe + 1/2O2 + H2O 1/2H2 + FeO(OH)

K = pp ·p

0.5H2

H2O O2

Direct reaction between Fe and H2O K = pp

0.75H2


Tuesday, Sept. 08, 2009 25/35

Example: 3/4Fe + 1/2O2 + H2O 1/2H2 + FeO(OH)p

H2OPhD thesis D. Hünert

DiscussionFe + CO

- 5000

Fe + CO2Fe + CO

C will form in any case!

ΔG

/J

600 °CT/°C500 °C400 °C

-65000


Tuesday, Sept. 08, 2009 26/35

T/°C

C bid

Discussion

Carbide formation

A ti it f C 2Activity of C = 2M23C6 or M7C3

may grow with

High driving forceto form Fe3C

y g

access C

G/J

ΔG

600°C

Fe3C most stable

T/°C


Tuesday, Sept. 08, 2009 27/35

T/°C


T = 600°C p = 1 bar

Gas in equilibrium gas - Fe

T = 600 C, p = 1 bar70CO2 + 29H2O + 1 O2

gas - Feslag – Fe + CaCO3 + CaSO4 + Na2SO4

Fe3O4 Na2CO3 H CO COS


Tuesday, Sept. 08, 2009 28/35

Fe3O4 Na2CO3 H2 CO COS

Corrosion Mechanism, initial situation

Fe + 3/2O + 3H O =2 Fe(OH) (g)Fe + 3/2O2 + 3H2O =2 Fe(OH)3(g)Cr + 3/2O2 + H2O = CrO(OH)2(g)Mn + ½O2 + H2O = Mn(OH)2(g)

Fe + CO2 = Fe3O4 + CC + O2 = CO + CO2Fe + CO2 = FeO + CO

3Fe +4 H2O = Fe3O4 + 4H2

2


Tuesday, Sept. 08, 2009 29/35

2 3 4 23Fe + CO2 + 2H2O = Fe3O4 + CH4

Corrosion Mechanism, < 1 Cr

Fe + C = Fe3C

Fe + CO2 = FeO + CO

C + O2 = CO + CO2

2Fe + O = 2FeO

3Fe+2H2O+CO2 = Fe3O4+C+2H2


Tuesday, Sept. 08, 2009 30/35

23/2Fe + CO2 = 1/2Fe3O4 + C

2Fe + O2 = 2FeO3/2Fe + O2 = Fe3O4

Corrosion Mechanism, 9 – 12 % Cr

Cr bonded in Me23C6Cr not fully available to form

t ti F C O C O


Tuesday, Sept. 08, 2009 31/35

protective Fe2CrO4 or Cr2O3

Conclusions I

Free carbon is formed and the source for carbide formationFree carbon is formed and the source for carbide formation and carburization.

– Existing carbides in 9 - 12% ferritic-martensitic steels will grow due to the offer of free Carbon.

– This mechanisms should not be neglected in lifetime calculations and lifetime experimentscalculations and lifetime experiments.

– The existing steels may not be usable up to their current working temperatures in Oxyfuel power plant atmospheres (This will be investigated in further experiments)(This will be investigated in further experiments).


Tuesday, Sept. 08, 2009 32/35

Conclusions I

-Cr content below 1 wt.% supports the formation of Cementite in the o ide scale and the steel to o ideCementite in the oxide scale and the steel to oxide interface.2% 12% Cr alloys exhibit intensive carburisation at-2% - 12% Cr alloys exhibit intensive carburisation at temperatures of 550°C and higher.Carburisation will influence ductility and creep rupture-Carburisation will influence ductility and creep rupture failure

-Cr is fixed in Me C phases and cannot contribute to the-Cr is fixed in Me23C6 phases and cannot contribute to the self protection against corrosion


Tuesday, Sept. 08, 2009 33/35

Thank you for attending this lectureThank you for attending this lecture.

Please, d t h it t t k tido not hesitate to ask questions

or to suggest further experiments.

[email protected]@bam.deAxel kranzmann@bam [email protected]


Tuesday, Sept. 08, 2009 34/35

A Kranzmann and D Huenert: Technologien für den Klimaschutz und ihre Anforderungen an Werkstoffe In: Chemie Ing TechnikA. Kranzmann and D. Huenert: Technologien für den Klimaschutz und ihre Anforderungen an Werkstoffe. In: Chemie Ing. Technik, Vol 78, Issue 12, pp1809-1817, 2006

1. D. Huenert, A. Kranzmann: Influence of pressure and chromium content on corrosion reactions at 600°C in a CO2-H2O atmosphere, Nace Corrosion 2008, New Orleans, paper 8447

H Nit hk D Hü t A K P ä ti d D t ll HT K i hi ht CO2 H2O At hä I• H. Nitschke, D. Hünert, A. Kranzmann: Präparation und Darstellung von HT-Korrosionsschichten aus CO2-H2O Atmosphären: In: Materialographie, 41. Metallographie-Tagung, 19-21.09.2007, Bremen

• D. Huenert, W. Schulz, A. Kranzmann: Corrosion of steels in H2O-CO2 atmospheres at temperatures between 500°C and 700°C. In: 15th International conference on the properties of steam and water, Konferenztagungsband auf CD, ICPWS XV / 06. Electrochemistry and Corrosion in High Temperature, Water (Electro. 12), ISBN: 978-3-931384-64-7, , Publisher VDI-GET, September, Berlin, 2008

• D. Huenert , W. Schulz, H. Nitschke, R. Saliwan Neumann, G. Oder, A. Kranzmann: Corrosion behaviour of ferritic and martensitic power plant steels under conditions of dual atmospheres, Nace Corrosion 2009, Atlanta, paper 9263

• A. Kranzmann, D. Huenert , H. Rooch, I. Urban, W. Schulz, W. Oesterle: Reactions at the interface between steel and oxide scale in , , , , ,wet CO2 containing atmospheres, Nace Corrosion 2009, Atlanta, paper 9265,

6. W. Schulz, D. Huenert, H. Nitschke, R. Saliwan-Neumann, A. Kranzmann: Comparison of the corrosion behaviour of 9-12% Cr steels in H2O, H2O-CO2 and H2O-CO2-O2, Nace Corrosion 2009, Atlanta, paper 9264

• D. Huenert, W. Schulz, A. Kranzmann: Impact of hot CO2 rich gases on steels, Clean Coal Conference (CCT), Dresden, 18.-21. MaiD. Huenert, W. Schulz, A. Kranzmann: Impact of hot CO2 rich gases on steels, Clean Coal Conference (CCT), Dresden, 18. 21. Mai 2009

• D. Huenert, W. Schulz, A. Kranzmann: Simultaneous Oxidation and Carburization under Oxyfuel conditions, Eurocorr 6.-10.09.2009, Nizza

10 D Huenert W Schulz A Kranzmann: Impact of H2O-CO2-O2 and H2O-CO2 atmospheres on the corrosion of ferritic-martensitic


Tuesday, Sept. 08, 2009 35/35

10. D. Huenert, W. Schulz, A. Kranzmann: Impact of H2O-CO2-O2 and H2O-CO2 atmospheres on the corrosion of ferritic-martensitic and austenitic steels. In: Dechema-Workshop 1-2.10.2009, Frankfurt mit Sonderdruck in Journal „Materials and Corrosion“ und in Buchserie Green-EFC-Series

Additional information


Tuesday, Sept. 08, 2009 36/35

1 barIntroduction: Test atmospheres

1 bar- H2O -> pO2 =8.4·10-12 bar- 30H2O + 70CO2 -> pO2 = 4.7·10-9 bar- 29H2O + 70CO2 + 1O2 -> pO2 = 1.0·10-2 bar29H2O 70CO2 1O2 pO2 1.0 10 bar- 28.5H2O +68CO2 + 1/2O2 + 2 N2 + 1SO2 -> pO2 = 3.2·10-3 bar

80 bar80 bar- H2O -> pO2 = 1.2·10-7 bar- 30H2O + 70CO2 -> pO2 = 8.6·10-8 bar

29H O + 70CO + 1O > 8 4 10 1 b- 29H2O + 70CO2 + 1O2 -> pO2 = 8.4·10-1 bar- 28.5H2O +68CO2 + 1/2O2 + 2N2 + 1SO2 -> pO2 = 8.1·10-2 bar

(Calculation Thermodynamic equilibrium at 600°C . Software and database Factsage 6.0, Fact53 database, constant volume)


Tuesday, Sept. 08, 2009 37/35

The cycleWater supply

Q Specimen and furnace Condensor

Q

CO2 – O2 supplyQO2 Content

O2

2

Pressure and Flow


Tuesday, Sept. 08, 2009 38/35

Flow control

MaterialsWt% Cr C Mn Si Al Ni Mo V W N B Co Cu

13CrMo44 0.61 0.13 0.57 0.28 0.04 0.19 0.46 0.004 10-3 0.024 10-4 0.01 0.27

S1* 1.3 0.32 0.73 0.08 0.01 69 0.99 0.28 0.01 0.024 10-4 0.01 0.05

T24 2.4 0.09 0.51 0.22 0.01 0.17 0.95 0.01 0.01 0.024 0.006 0.01 0.08

T92 8 9 0 14 0 45 0 32 0 02 0 24 0 36 0 2 2 04 0 3 0 008 0 02 0 07T92 8.9 0.14 0.45 0.32 0.02 0.24 0.36 0.2 2.04 0.3 0.008 0.02 0.07

S10* 10.3 0.14 0.43 0.07 0.01 0.83 1.04 0.17 0.97 0.39 0.002 0.01 0.02

X20 11.3 0.2 0.52 0.15 0.01 0.43 0.78 0.29 0.01 0.14 0.0014 0.02 0.08

Alloy B 11.5 0.13 0.17 0.46 0.01 0.2 0.25 0.21 1.41 0.36 0.006 1.49 0.07

DMV310N** 24.8 0.05 1.2 0.4 21.2 0.2

Compositions were measured in BAM VI.1* Experimental materials not commercial


Tuesday, Sept. 08, 2009 39/35

Experimental materials, not commercial** Producer certificate

Introduction: Test atmospheres

Basis Gas Main components of oxy-fuel flue gas

The gas composition 70 mol% CO2 and 30 mol% H2O

flue gas.No publications on reactions in the system were available in 2003H2O. in 2003.

The first Goal was to develop a understanding of the reactions between iron alloys and CO2 - H2O between 400°C and 700°C.The temperature depends on the alloy.


Tuesday, Sept. 08, 2009 40/35

Fe CF O(OH) Si Sim


Fe3CFeO(OH) Sim. Sim.

ferritic grain

FeO(OH) Fe + H2O Fe3C high C activity


Tuesday, Sept. 08, 2009 41/35

( ) 2 3 g y

Oxide scale microstructureResults of corrosion experiments

Oxide scale microstructure

C t

13CrMo44 X20CrMoV12-1

Cut

Fe3C/FeO layerCut

20 µm


Tuesday, Sept. 08, 2009 42/35


Carbides at the interface steel - oxide

Oxide

X20CrMoV12-1

Current state of evaluation

- 1 µm large M23C6 grains at the interface- Larger than typically microstructure elements


Tuesday, Sept. 08, 2009 43/35


Th d d f th i tThe pressure dependence of the corrosion rate indicates a direct reaction with CO2 and H2O

Gas transport in capillarities or pore channels

Gas reacts in the scale and at the interfaceGas reacts in the scale and at the interface

CO2, H2O and CO available at the interface

C formed in the corrosion reaction

Diffusion of C, formation of carbides, growth of


Tuesday, Sept. 08, 2009 44/35

Diffusion of C, formation of carbides, growth of carbides and carburization, locking of Cr.

R ti (E l )


Reactions (Examples)

Fe + CO -> FeO + C ; T > 575°C3/4FeO + H2O -> 1/4Fe3O4 + H2

3/ Fe + CO > 1/ Fe O + C ; T < 575°C3/4Fe + CO -> 1/4Fe3O4 + C ; T < 575 C3/2Fe + CO2 -> 1/2Fe3O4 + C ; T < 575°C1/2Fe + H2O -> 1/2FeO(OH) + 1/4H2

Water, CO2 and CO act independent at high temperatures


Tuesday, Sept. 08, 2009 45/35

Date post:	19-Mar-2022
Category:	Documents
Upload:	others
View:	4 times
Download:	0 times

3 Ageing and Corrosion of Steels in CO2 rich flue gases ...

Documents