rdf-lignite co-combustion in a cfb boiler et al.pdf · t_fg 795 c t_fg 820 c t_fg 810 c t_fg 650 c...

WIEN 48th IEA-FBC MEETING 24.5.2004

RDF-LIGNITE CO-COMBUSTION IN A CFB BOILER

Kari Peltola, Foster Wheeler Energia Oy, FinlandPekka Lehtonen, Foster Wheeler Energia Oy, Finland

Bernhard Röper, RWE Power AG, Germany

48th IEA-FBC Meeting / Wien / 24.5.2004

CO-COMBUSTION OF LIGNITE AND RDFIN A CFB BOILER


CO-COMBUSTION OF LIGNITE AND RDFIN A CFB BOILER

CONTENT OF THE PRESENTATION

• Description of the test equipment

• Analyses of the feedstock

• Course of the test runs

• Basic process parameters

• Probe tests- Fouling rate (corrosion)

• Comparison of the results to other plants

• Summary


TEST ARRANGEMENT - POWER PLANT

LIGNITE FIRING CFB

Steam data :• 77.8 kg/s• 510 ºC• 90 bar

Fuels :• Lignite• Sewage sludge• Lignite sludge• (Demolition

wood)• RDF

PROBE LOCATION

SUPERHEATER 4

SUPERHEATER 3

SUPERHEATER 2

ECONOMIZER

AIR PREHEATER


TEST ARRANGEMENT - DEPOSIT PROBE


TEST ARRANGEMENT - ELECTROCHEMICAL PROBE

Galvanic pair• different materials• deposit works as electrolyte


FUEL ANALYSIS

LIGNITE SLUDGE RDFMoisture % 52 73 28Ash % (in d.s.) 4.3 48 13Heat value MJ/kg (a.r.) 10.3 1.0 14.8Carbon (C) % (in d.s.) 65.0 24.7 50.3Hydrogen (H) % (in d.s.) 4.7 3.7 7.0Nitrogen (N) % (in d.s.) 0.84 3.3 0.98Sulfur (S) % (in d.s.) 0.37 1.5 0.17Chlorine (Cl) mg/kg (in d.s.)


TEST PROGRAM

Test Fuel mix Duration Load RDF RDF Sludge Coal

Hours % % (heat) %(mass) %(mass) %(mass)

#1 lignite+sludge 66 86 - - 25 75

#2 lignite+sludge 56 89 - - 20 80

#3 lignite+sludge+RDF 62 80 10 6 25 69

#4 lignite+sludge+ RDF 66 74 13 7 30 63


#6 lignite 70 63 - - - 100



OPERATION DURING THE TESTS

0

50

100

150

200

250

300

21.07.2003 00:00 27.07.2003 00:00 02.08.2003 00:00 08.08.2003 00:00 14.08.2003 00:00-

-

-

-

Steam ton/h HCl mg/Nm3 ZRA

#3RDF #1

#7RDF #4

#5RDF #3

#4RDF #2

#6 #2 #1


MAIN PROCESS PARAMETERS

Test run #1 #5 #6

Additional fuels Sludge SludgeRDF -

Load % 86 77 62T bed °C 811 789 807T cyclone °C 831 810 813O2 %, dry 4.0 3.7 4.1SO2 mg/Nm3 (1 115 60 68SO2 retention % 91 96 92Ca/S tot mol/mol 3.0 3.4 2.7CO mg/Nm3 (1 21 32 0NOx mg/Nm3 (1 154 104 124Hg µg/Nm3 (1 4 6 0HCl mg/Nm3 (1 15 49 14RDF share (2 % - 13 -(1 Emissions expressed in 7% O2 ; (2 Based on heat input


SOLIDS BALANCE OF FUELS

0

50

100

150

200

250

coal+sludge (#1) coal+sludge+RDF (#5) 100% lignite (#6)

Elem

ents

g

/s

0.0

0.5

1.0

1.5

2.0

2.5

ash

kg

/s

S Cl Ca Na K Mg Al Si Fe Mn Ti P ash

lignite

lignite + sludge

Share of fly ash >95 %


Particle size of fly ash

1

10

100

1000

lignite + sludge lignite + sludge + RDF 100 %lignite

part

icle

dia

met

er

µm

d(10) d(50) d(90)


Composition of fly ash and deposit

0

20

40

60

80

#1 #1 #5 #5 #6 #6

fly ash dep.in fly ash dep.in fly ash dep.in

%

Cl

S

Na

K

Ca

Fe

Mg

P

Si

Al

Ti

lignite + sludge 100 %lignitelignite + sludge +RDF


FOULING RATES MEASURED BY DEPOSIT PROBES

0.0

2.0

4.0

6.0

8.0

10.0

780 790 800 810 820 830Temperature (Cyclone) °C

g/m

2/h

#1#7

#6

#5

#4

#3

#2

100% LIGNITE


COMPARISON OF PROBE TEST RESULTS FROM BOILERS WITH DIFFERENT FUEL COMBINATIONS

0

5

10

15

20

25

30

Mixedwood

Mixedwood

Peat 38%+ mixed

wood

Peat 8% +mixedwood

Recycledwood

PDF RDF Lignite Lignite,sludge

Lignite,sludge,

RDF

120 MWth 120 MWth 157 MWth 157 MWth 63 MWth 91 MWth 59 MWth 235 MWth 235 MWth 235 MWth

FOU

LIN

G R

ATE

[g/m

2h]

0

1

2

3

4

5

6

CO

RR

OSI

ON

RA

TIN

G

Probe fouling rate Qualitative probe corrosion rating

Fouling controllable with conventional sootblowing

Challenging fouling behavior to be expected

T_FG600-650 C

206

T_FG795 C

T_FG820 C

T_FG810 C

T_FG650 C

T_FG650 C

T_FG820 C

T_FG700 C

T_FG650-700 C

T_FG810 C


CO-COMBUSTION OF LIGNITE AND RDF IN A CFB BOILERSUMMARY

MAIN CONTRIBUTING FACTORS TO SUCCESSFUL TEST RESULTS• the proportion of RDF was low

• tolerable content of Cl, Zn, Pb in RDF

• ash originating from wastewater sludge dominated the solids characteristics

• absorption or dilution of the fouling elements

• particle size of fly ash with sludge was coarser than ash from lignite alone

• chlorine corrosion was not detected


CO-COMBUSTION OF LIGNITE AND RDF IN A CFB BOILERSUMMARY

CO-COMBUSTION OFFERS AN ENERGY EFFICIENT WAY OF

THERMAL RECYCLING. HOWEVER, PROCESS CONDITIONS AND

BOILER CONSTRUCTION NEED TO BE EVALUATED INDIVIDUALLY

AND FOLLOWED UP DURING OPERATION


DEPOSIT PROBE AFTER 100% LIGNITE COMBUSTION

Flue gasflow

A

B

C

A) windward (dox. 105µm) B) side wall (dox. 90µm) C) leeward (dox. 30µm)

#1

#2

metal

oxide

deposit

#2#1

#3


DEPOSIT PROBE AFTER LIGNITE AND SLUDGE CO-COMBUSTION

Flue gasflow

A

B

#1

#2

A) Windward (dox. 50µm) B) Leeward (dox. 50µm)


DEPOSIT PROBE AFTER LIGNITE, SLUDGE AND RDF CO-COMBUSTION

Flue gasflow

A

B

C

B) side wall (dox. 40µm) C) leeward (dox. 30µm)A) windward (dox. 135µm)

#1#2

#3

#1

#2


FOR COMPARISON : PROBE IN 100% RDF FIRED BOILER

element %O 10.4Si 0.8S -Cl 7.0K 0.6Ca 0.8V 0.7Cr 29.2Fe 48.8Ni 2.1Sum 100.4


FOR COMPARISON : PROBE IN RDF /SLUDGE PILOT TEST

interface oxide oxideO 10.3 16.5 15.4Si - 3.6 3.0Al - 1.4 1.2S - 2.0 0.07*Cl 38.8 4.9 24.1K 4.4 1.6 15.3Ca 0.9 11.0 13.9Na - - 3.5Fe 38.9 59.0 22.2Cr 6.7 - -Cu - - 1.4SUM 100.0 100.0 99.9

O/Fe –molar ratio


INSTALLATION OF PROBES

Particle size of fly ashComposition of fly ash and deposit

rdf-lignite co-combustion in a cfb boiler et al.pdf · t_fg 795 c t_fg 820 c t_fg 810 c t_fg 650 c...

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