contribution to the analysis of the corrosion process of ... · alloys ☺ light-weight structural...

Department of Interface Chemistry & Surface EngineeringDüsseldorf, Germany

16th February 2010

Markus Schmitt, Michael Spiegel

[email protected]

Contribution to the analysis of the corrosion process of commercial steels and newly developed

laboratory alloys under simulated incineration conditions

Max-Planck-Institut für Eisenforschung GmbH 1NGBW IC – Oslo 16.02.2010

SP2: Conversion technologies

NGBW covers the supply chain:• SP 1: Fuel preparation• SP 2: Conversion• SP 3: Residue handling• SP 4: Wholesale of energy

NGBW objectives SP 2:

[excerpt] • in general:

innovative technologies to improve the corrosion resistance with the result of improved energy recovery, reliability and performance of waste and biomass combustion plants

• enhanced process conditions in order to achieve a higher efficiency→ reduction of corrosion and fouling problems

⇒ improving boiler materials in order to withstand HTC⇒ advanced boiler materials and new protecting coatings

• reducing maintenance costs by use of more corrosion resistant, but cost-effective materials and coatings→ target: double lifetime of heat exchange components at existing

steam temperatures


Waste-to-Energy Plant

region of interest

turbine

main corrosion attack

superheater

combustion grate

ash

electric power

superheater bundle

waterwall panel


Waste-to-Energy Plant: Conditions

Species in

Concentration [vppm]

HCl 560.0 2240.0SO2 35.0 700.0SO3 1.4 19.6NO2 71.5 214.5CO 64.0 640.0Pb 1.1 6.5Zn 3.5 51.7

Na+ K+ Ca2+ Pb2+ Zn2+ SO42- Cl-

№ 1 4.1 7.6 12.5 7.4 2.3 28.0 0.5№ 2 2.4 3.8 13.0 1.6 9.7 16.6 1.2

Flue gas concentration [excerpt]

Deposit constituents on WtE

superheater in wt.-% [excerpt]

Surface-Temperature:~ 400°C –

600°C

deposits

steam

sulphates

chlorides

flue gas

superheater tube


HTC Lab-Scale Facility Setup

gas supply unit

•

Lab-scale testing of materials and validation of testing methods using plant exposures

sample dimension: (10 x 10 x 3) mm3N2

O2

Ar-HCl

SO2

/CO2

furnace

exposure tubew/ sample holder

evaporatorunit

exposure unit


Testing Conditions

•

Gases (based on PREWIN conditions)

•

Synthetic deposits

HCl SO2 CO2 H2 O O2 N2

Waste 2,000 vppm 200 vppm - 15 vol.-% 8 vol.-% Bal.Biomass 200 vppm - 13 vol.-% 22 vol.-% 5 vol.-% Bal.

Na2 SO4 K2 SO4 CaSO4 ZnSO4 KCl ZnCl2

Waste/biomasssuperheater

33 wt.-% 33 wt.-% 33 wt.-%

Waste/biomasssuperheater

50 wt.-% 50 wt.-%

Wastesuperheater

25 wt.-% 25 wt.-% 25 wt.-% 25 wt.-%

Waste water wall

50 mol.-% 50 mol.-%


Commercial MaterialsMaterial Cr Ni Mo Mn Other

15Mo3 – – 0.30 0.52 C 0.16; Si 0.26

13CrMo4 4 0.96 0.07 0.48 0.46 C 0.12; Si 0.21

10CrMo9 10 (T22) 2.10 – 0.92 0.43 C 0.12; Si 0.22

7CrWMoVNb9 6 (T23) 2.3 – 0.15 0.27

C 0.06; Si 0.15; V

0.2; W 1.58; Nb

0.06; B 0.005; N 0.02; Al 0.02

X20CrMoV12 1 10.45 0.70 0.88 0.60 C 0.18; Si 0.22; V 0.26

X10CrWMoVNb9 2 (T92) 9.15 0.26 0.50 0.46

W 1.70; Si 0.22; Nb

0.6;N 0.05; V 0.2; B 0.003; C 0.11

Esshete 1250 14.90 9.65 0.94 6.25C

0.084; Si

0.58; Nb

0.86;V 0.22; B 0.004

TP 347 H 17.60 10.70 – 1.84 Si 0.29; C 0.05; Nb

0.6

Sanicro 28 27.00 31.00 3.50 ≤

2.00 C 0.02; Si 0.07; Cu 1.0

Inconel 625 22.00 Bal. 9.00 – Fe 3.0; Nb

3.5; C 0.025

HighCr-steels

Low Cr-steels

Ni-basealloy

HighCr-/Ni- steels


Model Alloys

Material [at.-%] Al [wt.-%] FeFe-15Al 7.9 bulkFe-26Al 14.5 bulk

Fe-40Al 24.4 bulk

• Iron Aluminides

α-Fe, Al: disordered A2 Fe3

Al: ordered D03

(600°C B2)FeAl: ordered B2

Material [wt.-%] Cr Al Si NiFe-9Cr-5Al 9.0 5.0 - -Fe-9Cr-2.5Al-2.5Si 9.0 2.5 2.5 -

Fe-9Cr-5Ni-2.5Al-2.5Si 9.0 2.5 2.5 5.0

• Modified 9%Cr-Steels (P91/T92)


Motivation: Modified

9%Cr-Steels

•

9-12%Cr ferritic-martensitic

steels:–

High strength and creep resistant steels suitable for use at temperatures up to 650°C

•

Coatings/alloy composition modification in Cr, Si, Al will improve corrosion resistance

•

Cr will enable and promote the outwards diffusion of Al

•

Cr-reservoir reduces Al/Si-amount needed to maintain external alumina or silica scale

•

Alumina scales are not as severely affected by steam as chromia, silica

•

> 5wt.% Cr, Si too high for industrial applications considering detrimental effects on metallurgical and mechanical properties


Motivation: Iron Aluminides

☺

Superior corrosion resistance in oxidising/sulphidising

atmosphere

☺

Much improved corrosion resistance under molten salt compared to

Fe-Cr

alloys

☺

Light-weight structural materials

☺

Recent efforts led to Fe-Al alloys have the potential to be used for structural applications at least between 650-800°C

☺

Development and improvement of Fe3

Al and FeAl

concerning high strength, high ductility and high creep resistance between 500-1,000°C

☺

Fe-Al-X alloys show better creep rates than P92


Corrosion Test: Commercial Steels


Corrosion Tests at 600°C for 336 h

15M

o3

13C

rMo4

4

10C

rMo9

10

T23

X20

CrM

oV12

1

T92

Ess

hete

125

0

TP3

47H

SAN

28

6250

50

100

150

300

400

500m

ass l

oss p

er u

nit a

rea

[mg/

cm²]

Biomass, KCl-K2SO4

Biomass, (Na2-K2-Ca)SO4

Waste, KCl-ZnCl2

Waste, (Na2-K2-Ca-Zn)SO4

increasing Cr, Ni content


Waste, (Na2

-K2

-Ca-Zn)SO4

, 600°C, 336 h


15M

o3

13C

rMo4

4

10C

rMo9

10

T23

X20

CrM

oV12

1

T92

Ess

hete

125

0

TP3

47H

SAN

28

6250

2 5

5 0

7 5

1 0 0

1 2 5

1 5 0

1 7 52 7 53 0 03 2 53 5 0

mas

s los

s per

uni

t are

a [m

g/cm

²]

4 5 0 °C 6 0 0 °C

Waste, (Na2

-K2

-Ca-Zn)SO4

, 600°C, 336 h High Cr-/Ni-contentHigh Cr-Low Cr-

T22


15M

o3

13C

rMo4

4

10C

rMo9

10

T23

X20

CrM

oV12

1

T92

Ess

hete

125

0

TP3

47H

SAN

28

6250

2 5

5 0

7 5

1 0 0

1 2 5

1 5 0

1 7 52 7 53 0 03 2 53 5 0

mas

s los

s per

uni

t are

a [m

g/cm

²]

4 5 0 °C 6 0 0 °C

High Cr-/Ni-content

Waste, (Na2

-K2

-Ca-Zn)SO4

, 600°C, 336 hw/o W, V w/ W, V

T22


0 5 10 15 20 25 30 100 150 200 250 300 3500

20

40

60

80

100

120

140

160m

ass c

hang

e pe

r un

it ar

ea [m

g/cm

²]

time [h]

10CrMo9 10 (T22) 7CrWMoVNb9 6 (T23)

Waste, (Na2

-K2

-Ca-Zn)SO4

, 600°C, 336 h

T22 w/o W, VT23 w/ W, V

HC Active Oxidation


Waste, (Na2

-K2

-Ca-Zn)SO4

, 600°C, 336 h

Low alloyed steel: T23 High alloyed steel: T92

250

µm

400

µm iron oxide

Fe/Cr-sulphidesFeCr2 O4(Fe,Cr)2 O3

CaSO4

+ WO3

+ 4HCl + 0.5O2→ CaWO4

+ SO2

+ 2H2

O + 2Cl2


0 500 1000 1500 2000 25000,0

100,0

200,0

300,0

400,0

500,0

Dis

tanc

e / [

µm]

cts.

Cl

10 h

FeCl2

/ FeSO4

0 500 1000 1500 20000,0

100,0

200,0

300,0

400,0

500,0

D

ista

nce

/ [µm

]

cts.

Cl

30 h

FeCl2

/ FeSO4

0 500 1000 1500 20000,0

100,0

200,0

300,0

400,0

500,0

Dist

ance

/ [µ

m]

cts.

Cl

100 h

FeCl2

/ FeSO4

T23: Waste, (Na2

-K2

-Ca-Zn)SO4

, 600°C


0

100

200

300

400

500m

ass l

oss p

er u

nit a

rea

[mg/

cm²]

Fe-Cr-W: Waste, (Na-K-Ca-Zn)SO4

, 600°C, 168 h

0 1 2 3 0 1 2 3

Fe-2.25Cr-x%W Fe-9.00Cr-x%W


0

20

40

60

80

100

120m

ass l

oss p

er u

nit a

rea

[mg/

cm²]

Fe-Cr-W: 600°C, 168 h w/o deposit

0 1 2 3 0 1 2 3

Fe-2.25Cr-x%W Fe-9.00Cr-x%W N2-8% O2

N2-8% O2-0.2% HCl N2-8% O2-0.2% HCl-0.02% SO2


Biomass, KCl-K2

SO4

, 600°C, 336 h


15M

o3

13C

rMo4

4

10C

rMo9

10

T23

X20

CrM

oV12

1

T92

Ess

hete

125

0

TP3

47H

SAN

28

6250

102030405060708090

100110120

mas

s los

s per

uni

t are

a [m

g/cm

²] 500°C 550°C 600°C

Biomass, KCl-K2

SO4

, 336 hLow Cr High Cr High Cr-/Ni-content


Biomass, KCl-K2

SO4

, 600°C, 168 h

0

25

50

75m

ass l

oss p

er u

n

T23

T92

T22

P91

mas

slo

sspe

r uni

tare

a[m

g/cm

²] w/o W w/ W w/o W w/ W


Corrosion Test: Modified 9%Cr-Steels / FeAl


Fe-1

5Al

Fe-2

6Al

Fe-4

0Al

Fe-9

Cr-

5Al0

20

40

60

80

100

120

140

160

180m

ass l

oss p

er u

nit a

rea

[mg/

cm²]

Summary: Corrosion Tests Fe-Al for 336 h Biomass, KCl-K2SO4, 600°C Biomass, (Na2-K2-Ca)SO4, 600°C Waste, KCl-ZnCl2, 320°C Waste, (Na2-K2-Ca-Zn)SO4, 600°C

increasing Al content


Waste, KCl-ZnCl2

, 320°C, 336 h


Fe-1

5Al

Fe-2

6Al

Fe-4

0Al

Fe-9

Cr-

5Al

Fe-9

Cr-

2.5A

l-2.5

Si

Fe-9

Cr-

5Ni-2

.5A

l-2.5

Si

T92

TP34

7H

0

20

40

60

80

100

120

140

mas

s los

s per

uni

t are

a [m

g/cm

²]

Mass Loss: 320°C, 336 h

Experiment 1

Experiment 2


Kinetic: Iron Aluminides, 320°C, 336 h

Fe-15Al Fe-26Al Fe-40Al

0 50 100 150 200 250 300 350

0

10

20

30

40

50

60m

ass c

hang

e pe

r un

it ar

ea [m

g/cm

²]

time [h]


iron oxideAl-rich oxide

Fe rich

iron oxide w/ ZnFe2 O4

solidified melt : Al-rich

100 h

100µm

Iron Aluminides: 320°C, 336 h

100µm100µm

Fe-26Al Fe-40Al

iron oxide

Al-rich oxide


Fe-

15A

l

Fe-

26A

l

Fe-

40A

l

Fe-

9Cr-

5Al 0

5

10

15

20

25

30

35

70

80

mas

s los

s per

uni

t are

a [m

g/cm

²]

Mass Loss: 320°C, 96 h, w/ KCl-ZnCl2 N2-8% O2-15% H2O N2-8% O2-15% H2O-200vppmSO2

N2-8% O2-15% H2O-2,000vppmHCl


Kinetic: Modified 9%Cr-Steels, 320°C, 336 h

Fe-9Cr-5Al Fe-9Cr-2.5Al-2.5Si Fe-9Cr-5Ni-2.5Al-2.5Si

0 50 100 150 200 250 300 350

0

10

20

30

40

50

60

mas

s cha

nge

per

unit

area

[mg/

cm²]

time [h]


Solubility of Pure Metals: 320°C, 100 h

Fe Al Cr Ni Si

0 20 40 60 80 100

1E-3

0.01

0.1

1

10

100w

ater

solu

ble

part

s [m

g/cm

²]

time [h]


Waste, (Na2

-K2

-Ca-Zn)SO4

, 600°C, 336 h


Fe-1

5Al

Fe-2

6Al

Fe-4

0Al

Fe-9

Cr-

5Al

Fe-9

Cr-

2.5A

l-2.5

Si

Fe-9

Cr-

5Ni-2

.5A

l-2.5

Si

T92

TP34

7H

05

10152025303540455055

120

160

mas

s los

s per

uni

t are

a [m

g/cm

²]

Mass Loss: 600°C, 336 h


Summary

•

Commercial steels–

decrease in mass loss by increasing Cr-/Ni-content

–

strong interaction of Cr and W concerning the degradation mechanism

•

Iron aluminides:–

improved corrosion resistance by increasing the Al-concentration

–

except: KCl-ZnCl2

-> Fe/Al ratio important for low corrosion

•

Modified 9%Cr-steels:–

beneficial behaviour

of Al, Si, Ni concerning ‘Active Oxidation’

–

Modifications show no increased corrosion performance at combined degradation mechanisms, i.e. ‘Hot Corrosion’

and ‘Active Oxidation’


Thank you for your attention!

contribution to the analysis of the corrosion process of ... · alloys ☺ light-weight structural...

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