Challenges in power production with biomass - High...

Challenges in power production

with biomass -

High-temperature corrosion

Chemistry in Energy Technology

March 11 – 15, 2019

Presented

by

Patrik Yrjas

Power production principle by combustion

- cooking water.....

Large-scale combustion techniques

Pulverized fuel firing – adapted

mainly for coal

Grate fired boilers – today

mainly for waste and smaller

scale biomass boilers

Fluidised bed boilers – suitable

for different kinds of fuels

Sumitomo SHI FW

(former Amec Foster Wheeler)

Fluidised bed boilers

Important for Finland, three major manufacturers

located here:

Sumitomo SHI FW (former Amec Foster Wheeler

Energia Oy) – BFB, CFB

Andritz Oy – BFB, CFB, recovery boilers

Valmet Technologies Oy - BFB, CFB, recovery boilers

CYMIC multi-fuel boiler

TSE, Naantali, FinlandSteam 144 / 130 kg/s

164 / 44 bar

555 / 555 C

390 MWth

(142 MWe, 244 MWheat)

Fuels: Wood biomass,

agrofuel, peat,

coal, SRF

Start-up: Fall 2017

Courtesy of Valmet Technologies Oy

Corrosion in power boilers

Wet corrosion of colder areas before stack (e.g. acid

dew point, hygroscopic deposits)

Corrosion of refractory material

Corrosion of steam side material/tubing

Corrosion on fire side material/tubing

- The major reason for efficiency limitations and

operational problems

- Rule of thumb: 10 ºC steam temperature increase,

increase plant efficiency by 2 %

Challenges in biomass combustion

High-temperature corrosionHigh-temperature corrosion refers to a chemical attack from

gases, solid or molten salts, or molten metals, typically at

temperatures > 300°C, but limit not strict. Examples of high-

temperature corrosion:

• Gas phase corrosion• Chlorination

• Oxidation

• Carburization

• Sulphidation

• Nitridation

• Solid and melt phase corrosion• Deposit composition and change (gas, fuel mix, etc)

Picture taken from: www.modernpowersystems.com

Source: Frandsen et al.

Slagging, fouling, and corrosion

Factors affecting corrosion

Material temperature

Steel composition

Deposit composition

Gas composition

Temperatures Wall tubes and drum

Temperature of supersaturated steam

(depends on pressure) ~ 300°C

Material temperature at walls +50°C

Superheaters

Steam ~ 400°C → 550°C (…600°C?)

Material

Radiation area+ 50°C

Convection area + 20-35°C

Economizers

Pre-heating of water max ~300°C

Air-pre-heaters

Pre heating of air (~120°C ±)

Steels

Most commonly used steels

Non alloy

Low alloy

High alloy

Stainless

And when ordinary steels are not enough

Composite =compound materials

Overlay welding

Metal spraying

Refractories

SteelsAlloying

Steels are made by combining iron (Fe) and carbon (C) which include

other elements as impurities or alloyed in purpose

Carbon content in steels usually 0,05-1%

– Cast iron (gjutjärn), if C > 2%

– The most important alloying element

– Affects the formation of microstucture (ferritic, martensitic, austenitic)

– Affects wide range of mechanical properties and fabrication characterization

C content increases C content decreases

tensile strenght toughness

hardness ductility

Classic improvers: Cr and Ni Cr: added to the steel to increase resistance to corrosion and

oxidation through Cr2O3 formation

Ni: tendency to form austenite results in a great toughness and high

strength at both high and low temperatures. Nickel also improves

resistance to oxidation and corrosion

Others: Mn, Mo, and Nb Mn: an austenite forming element, which improves hot working

properties and increases strength, toughness and hardenability (MnS

vs. FeS)

Mo: improves resistance to pitting corrosion, especially by chlorides

and sulphur chemicals

Nb: carbide stabilization, which tends to minimize the occurrence of

inter-granular corrosion; strengthens steels and alloys for high

temperature service

Steels

Grouping of steels

16Mo3, 13CrMo4-5, SA-209 Gr- T1,Low alloy steels 10CrMo9-10,

(Cr + Mo + Ni + Cu + V + Nb/Cb) > 5% 7CrMoVTiB10-10 SA-213 Gr. T11, T12, T22

High alloy steels, ferritic X10CrMoVTiB10-10 SA-213 Gr. T91, SA-335Gr. P91

Min. 13% Cr and max. 3% Ni

Stainless steels,1.4016, 1.4006, 1.4005 430, 410, 416

Min. 18% Cr and 3-6% Niferritic and martensitic

Stainless steels, 1.4162 (LDX 2101),austenitic-ferritic 1.4462 S32101, S32205

Min. 18% Cr and min. 7% Ni

Stainless steels, SA-213 TP347H,austenitic X7CrNiNb18-10 TP310HCbN

More Cr, Ni, Mo, Ce...

Special alloys, 2.4856

for e.g. Ni based (Sanicro 63, Alloy 625)

Fe, C, Mn, Si

EN materials ASME/ASTM materials

Non alloy steels P235GH, P265GH SA/A-210 Gr. A-1 and C, SA-106 Gr. B and C

Non alloy steels (Fe+C), carbon steels

May include manganese (Mn) and silicon (Si)

Very good availability, easy to weld

Price ~ 1,5 €/kg (P265GH)

Max design (material) temperature

– For pressure parts 450 oC

– For non-pressure parts 480 oC

Scaling temperature in air at 500 oC or little higher400

500

600

700

800

900

1000

1100

Grouping and use of steels

Examples of useFurnace walls, superheaters, boiler bank,

economizers, air preheaters (temperature below ~ 450 °C)

Grouping of steels

High alloy steels, ferritic X10CrMoVTiB10-10 SA-213 Gr. T91, SA-335Gr. P91










Fe, C, Mn, Si

Cr, Mo, Ni, Cu, V, Nb/Cb


Low alloy steels

16Mo3, 13CrMo4-5,10CrMo9-10,

7CrMoVTiB10-10

SA-209 Gr- T1,

SA-213 Gr. T11, T12, T22

Non alloy steels P235GH, P265GH SA-210 Gr. A-1 and C, SA-106 Gr. B and C

Low alloy ferritic steels

Molybdenum (Mo), chromium (Cr), vanadium (V), nickel (Ni)

Mo increases high temperature strength (0.5-1.0%)

increases both strength and resistance to scaling (0.5-2.5%)

increases creep strength at higher temperatures (max. 0.3%)

Use depending on strength values up to 575 °C

Very good availability

Price ~ 1,8 €/kg (16Mo3) to 3,3 €/kg (7CrMoVTiB10-10)

Requirements for welding increases with increasing alloying

elements

400

500

600

700

800

900

1000

1100

Cr

V

Mo

Cr


Examples of use

Furnace walls, superheaters, screen

tubes, boiler bank, economizers









Fe, C, Mn, Si



(Cr + Mo + Ni + Cu + V + Nb/Cb) > 5%

High alloy steels,

ferritic X10CrMoVNb9-1 SA-213 Gr. T91, SA-335Gr. P91

Low alloy steels

16Mo3, 13CrMo4-5,10CrMo9-10,

7CrMoVTiB10-10

SA-209 Gr- T1,

SA-213 Gr. T11, T12, T22


Grouping of steels

High alloy ferritic steels

Alloying elements over 5%

Economical use up to 600 ˚C

Limited availability

Challenging in welding

Price ~ 7-9 €/kg (X10CrMoVNb9-1)

400

500

600

700

800

900

1000

1100


Superheaters, main steam pipes

Examples of use







Fe, C, Mn, Si



(Cr + Mo + Ni + Cu + V + Nb/Cb) > 5%

24


Stainless steels,

ferritic and martensitic 1.4016, 1.4006, 1.4005 430, 410, 416

High alloy steels,

ferritic

X10CrMoVTiB10-10 SA-213 Gr. T91, SA-335Gr. P91

Low alloy steels

16Mo3, 13CrMo4-5,10CrMo9-10,

7CrMoVTiB10-10

SA-209 Gr- T1,

SA-213 Gr. T11, T12, T22


Grouping of steels

Ferritic and martensitic stainless steels

Ferritic (min. 13% Cr, max. 3% Ni)

Good corrosion resistance

Cheap price

Poor weldability

High tendency to embrittlement

NOT FOR PRESSURE BEARING PARTS

Martensitic (min. 13% Cr, max. 3% Ni)

Higher carbon content than with ferritic

Martensitic structure with heat treatment

Good strength-toughness properties

Moderate corrosion resistance

400

500

600

700

800

900

1000

1100


Martensitic stainless steels for e.g. to

turbine components and steam lines

Ferritic stainless steels not for pressure bearing parts

But are used for e.g in recovery boiler ash hoppers

Examples of use





Fe, C, Mn, Si


Min. 18% Cr and 3-6% Ni


(Cr + Mo + Ni + Cu + V + Nb/Cb) > 5%

27


Stainless steels, austenitic-ferritic

X2CrNi23-4, X2CrNiMoN22-5-3

SA/A-789 S1803

Stainless steels,


High alloy steels,

ferritic


Low alloy steels

16Mo3, 13CrMo4-5,10CrMo9-10,

7CrMoVTiB10-10

SA-209 Gr- T1,

SA-213 Gr. T11, T12, T22


Grouping of steels

Austenitic-ferritic stainless steels = Duplex steels

1) Lean duplex (LDX 2101)

2) ”Acid proof” duplex (2205)

3) Super duplex (2507)

Magnetic

Good corrosion resistance (especially against stress

corrosion cracking) and strength

Operating temperature below 300 oC (in pressure vessels

max. 250 oC )400

500

600

700

800

900

1000

1100


Used in evaporators (T > 150 °C), containers

and in pipings

www.outokumpu.com

www.ranflexmetals.com

Examples of use

http://www.outokumpu.com/

http://www.ranflexmetals.com/



Fe, C, Mn, Si





(Cr + Mo + Ni + Cu + V + Nb/Cb) > 5%


Stainless steels, austenitic

X7CrNiNb18-10 SA-213 TP347H, TP310HCbN



SA/A-789 S1803

Stainless steels,


High alloy steels,

ferritic


Low alloy steels

16Mo3, 13CrMo4-5,10CrMo9-10,

7CrMoVTiB10-10

SA-209 Gr- T1,

SA-213 Gr. T11, T12, T22


Grouping of steels

Austenitic stainless steels

Low carbon grade, L = C < 0,03%

Normal grade, C < 0,08%

Sensitization area 550-750 ˚C

Stabilized grades for temperatures between 550 and 750 ˚C

Not magnetic

High-strength and ductile

Brittleness in long-term, high temperature use

Challenges in bending

Limited availability of special grades (TP310HCbN,

347HFG, 253Ma)

400

500

600

700

800

900

1000

1100


Hottest superheaters, pipings

Plates, superheater ties, refractory anchors, tube shields…

(high T > 550°C)

Black liquor line, evaporator, vessels, cyclones

Examples of use

Fe, C, Mn, Si






(Cr + Mo + Ni + Cu + V + Nb/Cb) > 5%


Non ferrous alloys,

for e.g. Ni based

2.4856

(Sanicro 63, Alloy 625)

Stainless steels, austenitic

X7CrNiNb18-10 SA-213 TP347H, TP310HCbN



SA/A-789 S1803

Stainless steels,


High alloy steels X10CrMoVTiB10-10 SA-213 Gr. T91, SA-335Gr. P91

Low alloy steels

16Mo3, 13CrMo4-5,10CrMo9-10,

7CrMoVTiB10-10

SA-209 Gr- T1,

SA-213 Gr. T11, T12, T22


Grouping of steels

Special alloys, for e.g. Ni-based alloys

Iron not anymore the main element

To be used in really aggressive corrosive

environments

Applications: compound / composite tube + overlay

weldings

When ordinary steels are not

enough...

Examples of steelsW

eig

ht-

%Low

alloy

High alloy

steels Austenitic stainless steelsNi-based

alloys

Source: Cha et al.

Increasing Cr and Ni content

Increasing material costs

Steels

Combustion of biomass

Purpose:

To produce heat and electricity without increasing

the net-CO2 concentration in the atmosphere

Availability

Replace fossil fuels

F. Frandsen

Biomass sources

Tree derived - wood, branches, stumps, bark,

sawdust

Straw and energy crops (miscanthus, willow,

poplar, etc.)

Waste derived – demolition wood, agrofuels,

food processing residues (rice husk, bagasse,

corn cobs, etc.), and others

Note; biofuels often connected to processed

biomass such as ethanol, biodiesel, etc.

Biomass - ash forming matter

0

1

2

3

4

5

6

7

8

9

10

Wei

ght

% (

db

)

Rest

P

S

Cl

Na

K

Ca

Si

Based on data from the ÅA database: https://web.abo.fi/fak/tkf/ook/bransle/

https://web.abo.fi/fak/tkf/ook/bransle/

Ash chemistry of different fuel types

Coal => silicate based ash chemistry, Na, S and

Ca (in FBC when used for desulphurization)

Biomass => Ca, K, Na, S, and Cl (+Si in some

cases)

Agrofuels => Si, Ca, K, P, S and Cl

Waste fuels => .......... + Zn and Pb (+Br)

Challenging fuel mixesAmec Foster Wheeler´s fuel system:

Courtesy of Amec Foster Wheeler

Challenging fuel mixesValmet´s fuel system:

Corrosion by metal chloride and

sulphate deposits

Deposition of sulphates and chlorides occurs by:

• condensation from the gas phase

• attachment of small sticky particles

PbS

O4

Inner scale

Outer scale

Ref. Rainer Backman

The salt system melting stairs

Importance of composition to T0

Fe2O3

Corrosion mechanism

- ”active oxidation”

Fe

Metal/Fe, e.g. low alloyed steel, 16Mo3

KCl

O2, (H2O)

Cl-, Cl2

FeCl2

Fe2O3

Cl-

HCl

Cl2?

HCl, Cl2KOH

p(O2)increases

p(Cl2)increases

Cr2O3

Corrosion mechanism of Fe/Cr-steels

- initiation to ”active oxidation”

Fe/Cr

Metal; Fe/Cr, e.g. stainless steel, AISI347 (19% Cr)

KCl

O2, (H2O)

Cl-, Cl2MeCl2

Me2O3

Cl-

HCl

Cl2?

HCl, Cl2

K2CrO4

p(O2)increases

p(Cl2)increases

Cr2O3

KOH

Me = Fe, Cr

Active oxidation

First and most cited corrosion reaction mechanism

? Driving force for the chlorine diffusion

? The molecular sizes of O2, Cl-, HCl, Cl2, CrCl2,

FeCl2

Facts:

FeCl2, Fe2O3, Cr2O3

and K2CrO4 have

been identified as

corrosion products

Fe2O3

Corrosion mechanism

- ”active oxidation”

Fe

Metal/Fe, e.g. low alloyed steel, 16Mo3

KCl

O2, (H2O)

Cl-, Cl2

FeCl2

Fe2O3

Cl-

HCl

Cl2?

HCl, Cl2KOH

p(O2)increases

p(Cl2)increases

What can we do....?

Some research tools Laboratory methods

Furnace tests; materials exposed to synthetic ashes

at high temperature and a controlled gas atmosphere

Other used methods, e.g. DTA/TGA studies, camera,

isotopes (e.g. O18 and O16) etc.

Thermodynamic chemical equilibrium

calculations

Melting evaluations of salts, deposits and ashes

Pilot/bench-scale tests

Full-scale measurements

Temperature controlled corrosion and deposit probes

Sampling and SEM/EDX-analyses

High-temperature material exposure

testsSteels are cut to 20 mm x 20 mm in our workshop or delivered. Pretreated and covered with a synthetic

ash/salt/real ash. Five samples exposed at a time in a tube furnace with chosen atmosphere and

temperature. Afterwards steel samples are casted in resin, cut off the reveal cross-section and polished

and washed.

Pre-melted salt

Result treatment

Salt

Steel

Pasta Oxide layer

Oxide layer

Steel

Epoxy

Oxide layer

Steel

Steel

Salt particles

Salt particles

max.

min.

average

etc.

The cleaned cross-sections are studied in the SEM/EDX and the

oxide layer thickness (corrosion layer) is determined over the cross-

section. From the data we get differnt oxide layers values: mean,

max, min, median etc.

0

50

100

150

200

250

300

350

400

450

500

0 20 40 60 80 100 120 140 160

Oxide layer thickness, [µm]

Co

un

ts

Maxim

um

valu

e

Mo

st

co

mm

on

valu

e

Avera

ge

Med

ian

180

Counts as a function of oxide layer

thickness

53This figure shows the statistics as calculated from the measured oxide layer

thicknesses., mean median, min and max values can be determined

0

100

200

300

400

500

600

0 50 100 150 200 250 300

Oxide layer thickness, [µm]

Co

un

ts

Maxim

um

valu

e

Mo

st

co

mm

on

valu

e

Avera

ge

Med

ian

Counts as a function of oxide layer thicknessType 2

Percentage of counts as a function of oxide

layer thicknessDistribution of oxide layer

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

5

0 50 100 150 200 250

Thickness of oxide layer [µm]

%

Ash with no Cl

No ash

Ash with Cl

Examples of corrosion results, 168 h

(21% O2, 79% N2)

(Skrifvars et al. 2008)

0

20

40

60

80

100

120

140

Co

rro

sio

n layer

thic

kn

ess, m

m 1.3% Cl T0=522°C

0

20

40

60

80

100

120

140

Co

rro

sio

n la

ye

r th

ick

ne

ss

, m

m 0.3% Cl T0=526°C

0

20

40

60

80

100

120

140

Co

rro

sio

n layer

thic

kn

ess, m

m 0% Cl T0 = 835°C

0

20

40

60

80

100V

ikt-

%

Rest

Nb

Mn

Mo

Ni

Cr

Fe

Samples with KCl on 304L

K2CrO4

MeCl2

500°C

20 μm

Cr Fe

Ni O

K Cl

Cr Fe Mn Mo Ni Si nCr/nFe

304L (wt.%) 19.19 70.21 2.02 0.32 7.72 0.47

304L (at.%) 20.33 69.24 2.04 0.18 7.27 0.94 0.29

SEM-results; importance of pre-melting

10CrMo, 10%KCl + K2SO4 500oC

Salt prepared without melting

Salt molten for homogeneity

Waste case: Experimental – materials

and conditions

Fe; 96.0

Fe; 68.7

Cr; 2.2

Cr; 18.1 Ni; 10.9

0 % 20 % 40 % 60 % 80 % 100 %

10CrMo9-10

AISI 347

59

Compound Melting temp. Temperatures Time Atmosphere

ZnCl2 318 ºC 250 ºC

PbCl2 501 ºC 350 ºC 168 h ambient

ZnO 1975 ºC 450 ºC

PbO 888 ºC 550 ºC

Results – oxide layer thickness

x- the oxide layer thickness under the detection limit

60

80

33

5

240

356

7

38

5 4

108

70

9

0

50

100

150

200

250

300

350

400

250 350 450 350 450 550 550 550

Mean

oxid

e la

yer

thic

kn

ess

µm

Temperature ºC

10CrMo

AISI347

xx x x

ZnCl2 PbCl2 ZnO PbO

XX

XX

KCl

Results – oxide layer thickness evaluation (450 ºC)

61Internal attack steel

Oxide layerOxide layer

steel

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Oxide layer thickness µm

PbCl2 (Type 2)

10CrMo

AISI347

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Dis

trib

uti

on

%

Oxide layer thickness µm

ZnCl2 (Type 1)

mean 5 µm

mean 108 µm

mean 35 µm

mean 240 µm

Another case study:

Questions

Are Pb- and Zn- chloride mixtures corrosive at

lower temperatures (300, 350 ºC)?

Does the added sulphur influence on Pb- and

Zn-chloride induced corrosion?

Background - sulphur may decrease KCl induced

corrosion according to:

2KCl + SO2 + H2O +1/2O2 K2SO4 + 2HCl

Corrosion Tests Simulated flue gas composition 1:

15% CO2, 5% O2, 15% H2O, 500 ppm SO2, rest N2

Simulated flue gas composition 2:

15% CO2, 5% O2, 15% H2O, rest N2

Salts: PbCl2 (Tmelt = 501 ºC) and 52 KCl + 48 PbCl2 wt% (molar ratio 4:1, T0 = 411 ºC),

59 KCl + 28 PbCl2 + 13 ZnCl2 wt% (molar ratio 8:1:1, T0 = 210 ºC)

Test duration: 168 h

Steels: non-alloy and low-alloy

Test matrix: 24 samples

Steel Gas 1 - 300°C Gas 2 - 300°C Gas 1 - 350°C Gas 2 - 350°C

P235GH PbCl2 , PbCl2+KCl PbCl2 , PbCl2+KCl PbCl2+KCl,

ZnCl2+PbCl2+KCl

PbCl2+KCl,

ZnCl2+PbCl2+KCl

10CrMo PbCl2 , PbCl2+KCl PbCl2 , PbCl2+KCl PbCl2+KCl,

ZnCl2+PbCl2+KCl

PbCl2+KCl,

ZnCl2+PbCl2+KCl

16Mo3 PbCl2 , PbCl2+KCl PbCl2 , PbCl2+KCl PbCl2+KCl,

ZnCl2+PbCl2+KCl

PbCl2+KCl,

ZnCl2+PbCl2+KCl

Material Fe Cr Ni Mn Si Mo C N Ti V Nb Al P S Cu Co

10CrMo9-10 95,96 2,24 0,45 0,25 1,00 0,07 0,01 0,01

P235GH 97,17 0,30 0,30 1,20 0,35 0,08 0,16 0,01 0,03 0,02 0,02 0,02 0,03 0,02 0,30

16Mo3 98,70 0,30 0,30 0,35 0,35 0,90 0,20 0,01 0,03 0,01 0,30

SEM images of 16Mo3 exposed to

PbCl2/KCl at 300 °C

no SO2

SO2

100µm

200µm

200µm

100µm

SEM images of 16Mo3 exposed to

PbCl2/KCl at 350 °C

no SO2

SO2

Corrosion test results

10CrMo16Mo3

P235GH

0.0

50.0

100.0

150.0

200.0

Pb

Cl2

KC

l+P

bC

l2

KC

l+P

bC

l2

KC

l+P

bC

l2+

Zn

Cl2

Pb

Cl2

KC

l+P

bC

l2

KC

l+P

bC

l2

KC

l+P

bC

l2+

Zn

Cl2

300°C 350°C 300°C 350°C

15%CO2, 5%O2, 15%H2O, restN2

15%CO2, 5%O2, 15%H2O,500ppm SO2, rest N2

110

223 8 13

20

140 130

2 7 119

120

182 7 9

Corrosion layer thickness

10CrMo 16Mo3 P235GH

µm

SEM/EDX analyses of 16Mo3 exposed

to PbCl2/KCl at 350°C. No SO2.

Cl K

O Pb Fe

Fe-chlorides may decrease the melting point (312 °C)

A ring of studied steel is located in the probe tip

Ring temperature can be adjusted

Weight loss → Annual tube wall thickness loss (mm/year)

Cross section analyses → Corrosion and deposit

chemistry

Corrosion probe:

full-scale measurements

Field tests – probe measurements cont.

After exposure…

Detached probe ringUnexposed ring Ring after oxide removal

Corrosion probe fitted with 3 sample rings

Courtesy of Tor Laurén, ÅA

Cross-cut Section and Studies in

Scanning Electron Microscope (SEM)

Cross-section SEM-image of 10CrMo

oxide layer3 – 6 µm

2 h

560 C

Risk of probe failure

Result after first trial (1h 40 min) and the new probe

Earlier trialat the sameboiler

Temperature loggings of test rings in corrosion

probe – steady in short-term

540

545

550

555

560

565

570

575

580

585

590

20:00 20:15 20:30 20:45 21:00 21:15 21:30 21:45 22:00

Tsp (ring1)Tlog (ring2)

Time

°C

540

545

550

555

560

565

570

575

580

585

590

24.4.2009 25.4.2009 26.4.2009 27.4.2009 28.4.2009 29.4.2009 30.4.2009

Tlog (ring2)

Tset (ring1)

°C

Date

Temperature loggings of test rings in corrosion

probe – sometimes difficult to control in long-term

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 50 100 150 200 250 300

Cal

cula

ted

Mat

eri

al L

oss

[µ

m/h

]

Exposure time [h]

10CrMo

Sanicro 28

Calculated Corrosion Rate as Function of Time and Material

Long Time Exposure Included (560°C)

Remarks on full-scale tests Give data under real conditions

Short time exposure can be used for calculating a corrosion index

With short time exposure it is possible to test a larger test matrix at less expenses and with less risk of probe failure

It is also possible to have a good control of test conditions at short time tests

A challenge to control temperature of several test rings on one probe with just one temperature controller

Different ring materials behaves different during long term exposure, which can make bigger differences in material temperatures on the same probe

For more reliable corrosion rate measurement longer exposure times than 2h is needed (at least in this type of boiler)

Camera experimental set up

Sanicro 63 with KCl @ 548oC, air ambient,

first 90 min (1 frame/2 min)

One test run

Additional....

Related vocabulary

Tensile strength, draghållfasthet, tensión de rotura, murtolujuus

– The maximum amount of tensile stress that material can take before failure

– Rm [MPa]

Yield strength, sträckhållfasthet, límite de fluencia, myötölujuus

– The stress at which a material begins to deform plastically (non-reversible)

– Rp0.2 [MPa]

Impact strength, slaghållfasthet, resistensia al impacto, iskulujuus

– the ability of a material to absorb shock and impact energy without breaking

– testing of susceptibility to brittle fracture

Creep, krypning, deformación por fluencia lenta, viruminen

– slow failure mechanism (at high temperatures), may take years to occur

– a time-dependent, permanent deformation that occurs under stress

Sensitization, sensibilisering, sensibilización, herkistyminen

– precipitation of carbides at grain boundaries, causing the steel to be susceptible to

intergranular corrosion or intergranular stress corrosion cracking

http://www.hindawi.com/journals/ijelc/2013/970835/fig10/

Creep

Sensitization

http://sirius.mtm.kuleuven.be/Research/corr-o-scope/hcindex2/rltd2.htmhttp://www4.hcmut.edu.vn/~dantn/TWI/jk81.html

http://www.hindawi.com/journals/ijelc/2013/970835/fig10/

http://sirius.mtm.kuleuven.be/Research/corr-o-scope/hcindex2/rltd2.htm

http://www4.hcmut.edu.vn/~dantn/TWI/jk81.html

Ferritic:

Body

centered

structure

Austenitic:

Face

centered

structure

http://tenerife-training.net/Tenerife-News-Cycling-Blog/wp-

content/uploads/2008/11/hcp-fcc-bcc-close-packed-structures.jpg

http://tenerife-training.net/Tenerife-News-Cycling-Blog/wp-content/uploads/2008/11/hcp-fcc-bcc-close-packed-structures.jpg

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