FBC Challenges:

Current Research at ÅA-University

by

Patrik Yrjas

71st IEA-FBC, Seoul

Clustering Innovation Competence of

Future Fuels in Power Production

Project: CLIFF July 2014 - June 2017

http://web.abo.fi/fak/tkf/cmc/Cliff/

TAMPERE UNIVERSITY OF TECHNOLOGY

Work packages and tasks Task participants WP 0 Scientific co-ordination

Co-ordination (research, web-pages, meetings, etc.) AAU

WP 1 Fuels and Feedstock

1.1 Fuel advanced analysis and conversion characteristics AAU, Aalto

1.2 Elemental release TUT, AAU

1.3 Bed agglomeration AAU

1.4 Silicate based additives and corrosive vapors AAU

1.5 Plant measurements AAU, Aalto, TUT

WP 2 Theoretical and Modelling

2.1 MACT Rule; TSM8 – BREF AAU

2.2 Radiation heat transfer modelling LUT, VTT

2.3 Models for Kraft recovery boilers AAU, VTT, Aalto

2.4 Time dependent simulations of BFB furnace processes VTT, AAU

2.5 Improved understanding of FB bed processes VTT, LUT

2.6 Improve modelling of FB wall processes VTT

2.7 Gaseous NO formation/reduction modelling AAU

2.8 Fuel specific models AAU

WP 3 Materials

3.1 High temperature erosivity AAU

3.2 Deposit adhesion and sootblowing AAU

3.3 Corrosion – metals/coatings/refractories AAU

3.4 Corrosion – temperature gradient AAU

3.5 Corrosion – detailed mechanisms AAU, TUT

3.6 Use of isotopes in high temperature research AAU, TopA

WP 4 Information and international co-operation

4.1 Highlights from conferences, seminars and workshops AAU, VTT, TUT, LUT, Aalto

4.2 Invited speakers to project meetings AAU

4.3 International co-operation AAU, VTT, TUT, LUT, Aalto

In this presentation

Motivation – challenges

Task 1.3: Bed agglomeration

Task 1.4: Silicate based additives and

corrosive vapors

Task 3.3: Corrosion - isothermal tests

Task 3.4: Corrosion - temperature gradient

tests

100

90

80

70

60

50

40

30

20

10

0

80

70

60

10

20

30

40

50

90

100 0

0 10 20 30 40 50 60 70 80 90 100

CaO+MgO

K2O+Na2OSiO2

Fossil

Major ash-forming elements in different fuels

ÅA fuel database 5

100

90

80

70

60

50

40

30

20

10

100

90

50

40

30

20

10

60

70

80

0

0

0 10 20 30 40 50 60 70 80 90 100

CaO+MgO

K2O+Na2OSiO2

Fossil

Peat

ÅA fuel database 6

Major ash-forming elements in different fuels

100

90

80

70

60

50

40

30

20

10

0

80

70

60

10

20

30

40

50

90

100 0

0 10 20 30 40 50 60 70 80 90 100

CaO+MgO

K2O+Na2OSiO2

Fossil

Peat

Wood

Forest residue

Bark

Waste wood

w

o

owood derived fuels

ÅA fuel database 7

Major ash-forming elements in different fuels

100

90

80

70

60

50

40

30

20

10

0

80

70

60

10

20

30

40

50

90

100 0

0 10 20 30 40 50 60 70 80 90 100

CaO+MgO

K2O+Na2OSiO2

Fossil

Peat

Wood

Forest residue

Bark

Waste wood

w

o

owood derived fuels

Agricultural residue

ÅA fuel database 8

Major ash-forming elements in different fuels

Ash chemistry of different fuel types

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

Biomass => Ca, K, Na, S, and Cl

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

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

Black liquor => Na, K, S and Cl

FBC issues

New, more challenging fuels

Multi-fuel combustion

More power – superheater corrosion

Standard laboratory ash vs. real boiler ash

Advanced analysis of ash forming matter and

prediction of ash behavior – fouling, slagging,

de-fluidization

Task 1.3 Bed agglomeration The lab-scale fluidized bed reactor

0

100

200

300

400

500

600

700

800

845

850

855

860

4800 6000 7200 8400 9600 10800120001320014400

Pre

ss

ure

dro

p [

pa

]

Te

mp

era

ture

[°C

]

Time [s]

KCl at 850°C

T1

T2

Δp

Defluidization after 12 g (0.5 g/10 min) or 3.1 weight-% of bed weight

300

400

500

600

700

800

890

895

900

905

910

0 600 1200 1800 2400 3000 3600 4200

Pre

ss

ure

dro

p [

pa

]

Te

mp

era

ture

[°C

]

Time [s]

K2CO3 at 900°C

T1

T2

Δp

Defluidization after 3 g (0.5 g/10 min) or 0.8 weight-% of bed weight

KCl 850°C 870°C

• No observed reaction with the

sand particles

• KCl acts as glue

Pure KCl, no

reaction layer

SEM/EDX images of bed particles

K2CO3 750° C

• Reacts with the sand particles forming potassium silicates

900° C

SEM/EDX images of bed particles

Other tests done so far

Phosphate salts “Agglomeration mechanisms in a laboratory bubbling fluidized bed due

to addition of different phosphate compounds”, C. Sevonius, P. Yrjas, D.

Lindberg, M. Hupa, 22nd FBC, Finland 2015.

Algea and wood mixtures “Agglomeration tendencies of algae and wood mixtures in fluidized

bedincineration“, C. Sevonius, P. Yrjas, P. Piotrowska, M. Hupa, D.

Boström, Conference on Impacts of Fuel Quality on Power Production,

USA 2014.

NaCl and Na2CO3 to be submitted

Peat (at 900°C)

Absorption of gaseous KCl

with kaolin/coal ash => lower

corrosion potential Al2O3∙2SiO2(s) + 2KCl(g) + H2O(g) =>

K2O∙Al2O3∙2SiO2(s) + 2HCl(g)

Use of S-additives may cause

a more rapid deactivation

SCR-catalysts 2KCl + SO2 + 1/2O2 + H2O =>

K2SO4 + 2HCl

Task 1.4: Silicate based additives and

corrosive vapors

Sample holder

Hole for the feeding pipe

Air holes

KCl crucible holder

Lower tube

Test setup

Start of experimentTimer stopped when sample was

Example results

* About 300 g/kg is the max. assuming stoichiometry according to:

1. Al2Si2O5(OH)2 Al2O3*2SiO2 + 2H2O (at about 550oC)

2. Al2O3*SiO2 + 2KCl + H2O K2O*Al2O3*2SiO2 + 2HCl

Task 3.3 Corrosion Isothermal corrosion test method at ÅA

Data treatment

Salt

Steel

Paste Oxide layer

Oxide layer

Steel

Epoxy

Oxide layer

Steel

Steel

Salt particles

Salt particles

max.

min.

average

etc.

Corrosion results, 168 h, (Na, K)2SO4

+(Na,K)Cl

(Skrifvars et al. 2008)

0

20

40

60

80

100

120

140

Co

rro

sio

n la

ye

r th

ick

ne

ss

, 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 la

ye

r th

ick

ne

ss

, m

m 0% Cl T0 = 835°C

0

20

40

60

80

100 W

eig

h-%

Rest

Nb

Mn

Mo

Ni

Cr

Fe

“Demolition wood salts”

x- the oxide layer thickness under the detection limit 24

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

th

ick

nes

s µ

m

Temperature ºC

10CrMo

AISI347

x x x x

ZnCl2

Tmelt= 283°C

PbCl2

Tmelt= 501°C

ZnO

Tmelt= 1975 °C

PbO

Tmelt= 886 °C

X X

X X

X = KCl, Tmelt= 770 °C Ref. Dorota Bankiewicz et al., 2012

SEM/EDX studies

10CrMo Fe Cr O K Cl

Task 3.4 Corrosion - temperature

gradient effect on salt and corrosion

Steep temperature

gradient over

superheater and

deposit (surface =>

gas)

Laboratory

simulations

Measured temperatures

Ring

Salt

Temperatures:

Sample ring ~ 390°C

Salt ~ 475°C,

Above the salt ~ 760°C

Furnace ~ 900°C

Sintered-

partly molten

Non-sintered

T0 = 537°C

T0 = 626°C

NaCl

Eutectic

salt mix

Na2SO4

Camera experimental set up

Sanicro 63 with KCl @ 548oC, air ambient,

first 90 min (1 frame/2 min)

One test run

Thank you