the mechanisms of corrosion – and how to avoid it them? · partikel analysis dilution air ejector...

This Project was co-financed by the Baverian Ministery for Environment, Health and Consumer Protection within the European Regional Development Fund (ERDF)

The Mechanisms of Corrosion –

and how to avoid it them?

Dr.-Ing. Ragnar Warnecke, GKS, Schweinfurt

Dr. rer. nat. Bernd Benker, CUTEC, Clausthal-Zellerfeld

Dipl. Phys. Christian Deuerling, GKS, Schweinfurt

Prof. Dr. Ferdinand Haider, Univ. Augsburg, Augsburg

Prof. Dr. Siegried Horn, Univ. Augsburg, Augsburg

Dr. Jürgen Maguhn, GSF, Neuherberg

Dipl.-Ing. Volker Müller, GKS, Schweinfurt

Dipl. Chem. Hermann Nordsieck, BIfA, Augsburg

Dipl. Phys. Barbara Waldmann, Univ. Augsburg, Augsburg

Prof. Dr. Ralf Zimmermann, GSF, Neuherberg

ISWA -Beacon-Conference, 25.-26. October 2007, Malmö 2


Content

Introduction!

Understanding?

Solution?

Summary / Perspective!



1. Introduction

GKS = Coal-, Gas and WtE-CHP-Plant



Flow Chart of GKS GmbHC-CHPP Steam Parameters:

115 bars; 535 °C

WtE-CHPP Steam Parameters:

65 bars; 435 °C



Availability = Economy

-14,00

-12,00

-10,00

-8,00

-6,00

-4,00

-2,00

-

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131

Zeit [Tage]

Dru

ckd

iffe

ren

z [m

bar]

Feuerraum

2. Zug

vor ÜH 5

vor ÜH 6

vor ÜH 4

vor ÜH 3

vor ÜH 2

vor Eco

Kesselende

-5

5

15

25

35

45

55

65

75

85

95

25.09.2007

13:55:12

25.09.2007

14:02:24

25.09.2007

14:09:36

25.09.2007

14:16:48

25.09.2007

14:24:00

25.09.2007

14:31:12

25.09.2007

14:38:24

25.09.2007

14:45:36

25.09.2007

14:52:48

25.09.2007

15:00:00

25.09.2007

15:07:12

Zeit

mm

t/h

SPW Menge 13LAB20CF301.ZQ01 FD Menge 13LBA10CF901.ZQ01 Trommelniveau 13HAD01CL302.XQ01

Deposits

Corrosion



Extended Corrosion Diagram - WtE

Extended corrosion

Diagram [Warnecke, 2003]



Green Layer:

Mainly S and

Fe (FeS2)

Thickness:

~ 100 – 200 μm

Blue Layer:

Mainly O und

Fe (Fe2O3 )

Thickness:

~ 800 – 1200 μmAlkali- and Earth-

alkali chlorides

Alkali- and Earth-

alkali sulfates

Red Layer:

Mainly Cl and Fe

(FeCl2)

Thickness:

~ 100 – 250 μm

H2O- /

Tubeside

Deposits-/

Flue gas side

2. Understanding?

HTCl-Corrosion



Examples for Coupling CFD and TEC

Used Programs:

CFX and FactSage

GKS-WtE-Boiler:



Dilution-

Air PTD

Boiler wall

Cyclone

Gas analysis

Conden-

sation

Pump

Volume

Flow

Meas.

Partikel analysis

Dilution air Ejector diluter

300 °C

Inlet-nozzle

Porous tubediluter

Raw gas

Drying

Analysis

Sampling

Cyclone

Ejector diluter

Isokinet.Divider

100nm 1 m 10 m 100 m 1mm10nm

ELPI – Online (30nm-10 m)

APS - Online (800nm-20 m)

Cyclone (>20 m)

Inlet curve

Berner-Low pressure-Impactor (<62nm - 10 m)

10 %

25 %

65 %

Mas.%:

“Button hook”

Curved Inlet



Measurement, identified Species at 600 °C;

2. Pass

Calculation with FactSage: Main species at 600°C

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

SiO2

ZnAl2O4(s)

ZnCl2(g)

K2ZnCl4

K3OCl

KCl(Mischph.)

KCl(g)

K, NaCl

NaCl(Mischph.)

K2SO4(Mischph.)

K3Na(SO4)2

Na2SO4(Mischph.)

CaSO4(Mischph.)

Ca5HO13P3(s)

KAlSi2O6(s)

PbCl2(g)

Fe2O3(s)

Mn2O3(s)

NiO(s)

Mg2SiO4(s)

CrSO4(Mischph.)

CrCl2(Mischph.)

(CuCl)3(g)

(CuO)(Fe2O3)(s2)

CaTiO3(s)

V2O5(s)

CuBr3(g)

amorph

0%5%10%15%20%

SiO2

ZnAl2O4(s)

ZnCl2(g)

K2ZnCl4

K3OCl

KCl(Mischph.)

KCl(g)

K, NaCl

NaCl(Mischph.)

K2SO4(Mischph.)

K3Na(SO4)2

Na2SO4(Mischph.)

CaSO4(Mischph.)

Ca5HO13P3(s)

KAlSi2O6(s)

PbCl2(g)

Fe2O3(s)

Mn2O3(s)

NiO(s)

Mg2SiO4(s)

CrSO4(Mischph.)

CrCl2(Mischph.)

(CuCl)3(g)

(CuO)(Fe2O3)(s2)

CaTiO3(s)

V2O5(s)

CuBr3(g)

amorph

Discrepancy: Calculation - Measurement



0.0001

0.001

0.01

0.1

0.01 0.1 1 10 100 1000 10000

Partikelgröße [ m]

Massen

ko

nzen

trati

on

[g

/m_]

Z1 Z1 Trend Z2 Z2 Trend Z3 Z3 Trend Z4 Z4 TrendAverage of 3 - 8 Measurements

Normal Operation:

Particle Distribution

Aerodynamic particle diameter [ m]

Ma

ss c

on

ce

ntr

atio

n [

g/m

3]



Normal operation:

Chemical Composition of Particles – 3 Summed Fractions

Mittlere Zusammensetzung Zug 1

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

< 1 m 1-20 m > 20 m

Partikelfraktion

An

teil

Rest

Cl

S

Pb

Zn

K

Na

Ca

Si


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

< 1 m 1-20 m > 20 m

Partikelfraktion

An

teil

Rest

Cl

S

Pb

Zn

K

Na

Ca

Si


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

< 1 m 1-20 m > 20 m

Partikelfraktion

An

teil

Rest

Cl

S

Pb

Zn

K

Na

Ca

Si


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

< 1 m 1-20 m > 20 m

Partikelfraktion

An

teil

Rest

Cl

S

Pb

Zn

K

Na

Ca

Si

Fine fraction:

Secondary particle

(Na, K, Cl)

• Cl-high,

decreasing

• S-low,

partially increasing

Coarse fraction:

Primary particle

(Ca, Si)

• Ca-high

• “Balance" increasing

Particle Fraction Particle Fraction

Particle Fraction Particle Fraction

Ra

tio

Ra

tio

Ra

tio

Ra

tio

Average Composition Pass 1 Average Composition Pass 2

Average Composition Pass 3 Average Composition Pass 4



Normal Operation:

(De-)Sulphidation

Gas-phase: Particle-phase (< 0,2 m):

Chem

ical equiv

ale

nts

(H

Cl;

S/2

)[M

ol/k

g]

0

2

4

6

8

10

12

14

pass passpass passpass pass518 n1 518 n1 519 n2 519 n2 519 n3 519 n3

1st 2nd 1st 2nd 1st 2nd

SCl

Chem

ical equiv

ale

nts

(H

Cl;

SO2

/2[m

Mo

l/m_

ST

P]

SO2

HCl

pass passpass pass1st BE BE2nd2nd 1st

519 n2 519 n2 519 n2 519 n3 519 n3 519 n3

0

10

20

30

40

50

60

BE = Boiler End



Total Length ca. 3 m

Material Probes

Ceramic rings

Water Fitting

Fittings for Thermocouples

Air Inlet

Corrosion Sensor

Water cooled lance

Air cooed sensor head

Electrical contacts for measurement



Comparison: Plant Tubes vs. Sensor

3 months plant tubes: 3 months sensor rings:

FeaClb

FecSd

FeeOf

Alkali-Cl

Alkali-S

TubeTube

Example:

Identical Structure of Tube and Sensor!



Thickness of Layers

Iron Oxid

Tube Reduction

Iron Chorine

Layer

Thic

kness [

m]



Correlation: Wall decline vs.

Corr.-signal

Probe of 15Mo3

Ceramic ringsRing 1: 15Mo3Ring 1: 15Mo3

Ring 2: InconelRing 2: Inconel

Ring 3: 15Mo3Ring 3: 15Mo3

UU

(a) free corrosion potential(a) free corrosion potential

Ring 1: 15Mo3Ring 1: 15Mo3

Ring 2: InconelRing 2: InconelRing 3: 15Mo3Ring 3: 15Mo3

(b) power-voltage-line(b) power-voltage-line

II



Sensor data – systematic temperaturevariation

Corrosion conductance is depending exponentially on temperature



FexOy

15Mo3

Metal sulfateMetal chlorine

FexOy+MClx+MSOy

Cl2

FexOy

O2, HCl, Cl2

FeCl2+x

O2

FeCl3(g)

FexOy

Cl2

Cl2FeCl3

FeCl3(g)

FeCl2

FeCl2 Ion

transport

Gas

transport

• 15Mo3/FeCl2 :

•FeCl2/FexOy:

•Fe2O3/Fe3O4:

232224234 ClOFeOFeCl ++

2332 FeClFeFeCl +

32222 ClFeClFeCl +



2442422223,,33,2,2 ClCaSOSOKSONaOSOCaClKClNaCl +++

Reactions at boundary layers

(not complete

until now!)



grate

co

rro

sio

n o

f tu

be

fouling/tube

Close-up Range

combustible

org.

S / Cl

anorg.

S / Cl

combustion

chamber (S/Cl)

grate system

air system

plant

"slag-

particle"

condensable

matter (salts,

metals, etc.)

HCl

SOx

NextGenBioWaste

calcination changes during flight

Physics

coarse

X

middle

Y+

small

z -

Conden-

sable

Salts ?

coarse

(>20 )

middle

(1<x<20 )

small (<1 )

se

dim

en

tatio

n

co

nd

en

sa

tio

n

ag

glo

me

ratio

n

>500 m

1200°C 1050°C 800°C 550°C

su

lph

atio

n

Cl –

S +

Cl ?

S ?

HCl +

SOx -

Stokes

approach to border

Physics

Distant Range

tra

nsp

ort

to b

ord

er

ad

he

sio

n

pa

rtic

le

fou

ling

-

an

alo

gy

+++Impaction

+Impaction

Thermophoresis

Interception

(+)ThermophoresisTurbophoresis

?

?

?

?

?

?

Physics Chem.

Rest

O2, H

2O, ...

Diffusion

no

vapor

pressure

yes

yes

yes

ga

s d

.

su

rfa

ce d

.

chloride, gaseous

HCl

SOx

Rest

(O2,

H2O, ...)

yes

yes

yes

active layer

su

lph

atio

n

Cl (-)

S (+)

Cl –

S +

Cl –

S +

O2 –

H2O --

SOx--

HCl ++

[Cl]

FexO

y

barrier

EFRE-KORREFRE-KORR

STOP

STOP

STOP

STOP

2 FeCl2 + [Cl] 2 FeCl

3

2 FeCl3 + Fe 3 FeCl

2

Fe2O

3 + Fe 3 FeO

e.g.

FeS, FeOx

grate

slag

1st pass 3rd pass2nd pass Super heater

++

+

+

++

+

Chem.Chem.

Comb. Ch.

outer layer

400°C



How to avoid HT-Chlorine-Corrosion?

Chlorine Trap

HWS

At superheater:



Crossover 2./3. Pass: Chlorine TrapActual situation:

3 vaporiser tubes (distance:

400 mm)

Future condition:

T=180

(distance: 100 mm)



HWS



HWS – Effect of Cleaning



Adding SulphurDirect sulphur and SO2

Increasing of sulphur content, without reducing chlorine


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

< 1 m 1-20 m > 20 m

Partikelfraktion

An

teil

S-pellets (30,18 kg/h) - Mittl. Zus.-setzung Zug 3

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

< 1 m 1-20 m > 20 m

Partikelfraktion

Rest

Cl

S

Pb

Zn

K

Na

Ca

Si

Schwefelpellets, Mittelwerte, Vgl. m. Normalbetrieb 060801

0.00001

0.0001

0.001

0.01

0.1

1

10

0.01 0.1 1 10 100 1000 10000

Partikelgröße [ m]

Ma

ss

en

ko

nze

ntr

ati

on

[g

/m?

]

Z2, SP, Mittelwert Z3, SP, Mittelwert Z2, NB, 060801 Z3, NB, 060801



4. Summary / Perspective

Boiler influences Gas/Aerosol within FG way

Chlorine layered large particles depositing by impaction

Interaction between flue gas and particles: sulphidation withrelease of chlor(ine) in the deposits

Chlorine trap shall catch chlorides before SH

Attack of chlorine should be modified by usingprocess know-how or depositing protection layers

Next step: Better understanding of chlorine formation in thecombustion chamber (NGBW)

the mechanisms of corrosion – and how to avoid it them? · partikel analysis dilution air ejector...

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