behavior of sulfur during circulating fluidized bed oxyfuel combustion · 2013. 9. 25. · behavior...

Behavior of sulfur during circulatingfluidized bed oxyfuel combustion

Results from an ADECOS-CFB Programme

Faculty for Mechanical Engineering – Institute for Energy Engineering. – Chair for Combustion, Heat and Mass Transfer

Ponferrada, 10.09.2013

Ing. Miroslav ČechDr.-Ing Andreas HillerProf. Michael Beckmann

2

Project ADECOS CFB

Motivation

Fluidized Bed Test Rig

Results of own research

Economical aspects

Conclusion and Outlook

Behavior of sulfur in CFB-Oxy CombustionPonferrada, 10.09.2013

3

Project ADECOS ZWSF

Motivation



Economical aspects



Project ADECOS ZWSF

Further development and research of Oxyfuel-Prozesson CFB-Firing, aimed on technical and economical feasibility

Teilprojekt 2ZWSF-Dampferzeuger einschl.

Rauchgasweg und -reinigung

Teilprojekt 1Simulation und Optimierung

des Gesamtprozesses

Teilprojekt 3Verbrennungsuntersuchungen

mit Braunkohle

Teilprojekt 4Verbrennungsuntersuchungen

mit Steinkohle

Project part 2CFB-Boiler simulationwith flue gas cleaningand desulphurization

Project part 1Simulation and

optimalization ofwhole process

Project part 3Experimental part

using Lignite

Project part 4Experimental partbituminous coal

4Behavior of sulfur in CFB-Oxy CombustionPonferrada, 10.09.2013

Project ADECOS ZWSF

Motivation



Economical aspects


Main Advantage of CFB :

-Easy desulphurisation in the combustion Chamber-Effective and cost reducing

…will be different under Oxyfuel conditions:

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

500 600 700 800 900 1000 1100

Part

ial p

ress

ure

CO2

[bar

]

Temperature [°C]

CO2-CaCO3 equilibrium curve, replotted from E.H. Baker, The Calcium Oxide Carbon Dioxide System in the Pressure range 1-300 atm, J.Chem. Soc. 87 (1962), P 464-470

Direct Sulfation:

Indirect Sulfation:

Oxyfuel ->


Project ADECOS ZWSF

Motivation



Economical aspects

Conclusion and Outlook …will be removed under Oxyfuel-Modus:

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

500 600 700 800 900 1000 1100

Part

ial p

ress

ure

CO2

[bar

]

Temperature [°C]

CO2-CaCO3 balance curve, replotted from E.H. Baker, The Calcium Oxide Carbon Dioxide System in the Pressure range 1-300 atm, J.Chem. Soc. 87 (1962), P 464-470

Direct Sulfation:

Indirect Sulfation:

Oxyfuel ->

6

CFB Test Rig

• Power output: 300 kW

• Primary Air / Recirculated Flue gas / O2

• Secondary Air /Recirculated Flue Gas /O2

• Design fuel: Lignite„Lausitzer Trockenbraukohle“

Ash 5,3 %massWater 18,2 %massCarbon 51,6 %massHydrogen 3,8 %massNitrogen 0,51 %massSulphur SCOMBUSTIBLE 0,583 %massChlorine 0,036 %massLower Heating Value 19,1 MJ/kg

Ca in the ash 15,56 %mass

Project ADECOS ZWSF

Motivation



Economical aspects


7

• Cooling via integrated fluid bed cooler

• Valve and bed cooler fluidized by air/CO2

• Combustion chamber Ø320mm

• Height 12 m

12 0

00

Project ADECOS ZWSF

Motivation



Economical aspects


Folie 8

Gas Concentration Measurement

‘‘Cyclone 2‘‘ Sampling

‘‘Filter‘‘ Sampling

9

Motivation

Recent research on SO2-Emissions



SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

Economical aspects



Comparison of SO2 Emissions between Air and Oxy firing mode: Variation of air excess

Air Mode Oxy Mode

SO2

SO2Max

0

100

200

300

400

500

600

700

0 2 4 6 8 10

SO

2[m

g/M

J BS]

Rest O2,dry [%vol]

SO2

SO2Max

0

100

200

300

400

500

600

700

0 2 4 6 8 10

SO

2[m

g/M

J BS]

Rest O2,dry [%vol]

840-880°C, 230 kW, no sorbent,no air staging

820-900°C, 230 kW, no sorbent1,2-5% N2 in flue gas, RR=62,5%


Comparison of SO2 Emissions between Air and Oxyfiring mode: Variation of air excess

Air Mode Oxy Mode

SO2

SO2Max

S Ash 5.2

5.4

5.6

5.8

6

6.2

0

100

200

300

400

500

600

700

0 2 4 6 8 10

S in

Ash

[%

MASS]

SO

2[m

g/M

J BS]

Rest O2,dry [%vol]

SO2

SO2Max

S Ash

5.2

5.4

5.6

5.8

6

6.2

0

100

200

300

400

500

600

700

0 5 10

S in

Ash

[%

MASS]

SO

2[m

g/M

J BS]

Rest O2,dry [%vol]

840-880°C, 230 kW, no sorbent,no air staging, XRF-;Method for S content in ash

820-900°C, 230 kW, no sorbent0-2% N2 in flue gas, Recycle Rate=62,5%

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

Economical aspects


Ponferrada, 10.09.2013 Behavior of sulfur in CFB-Oxy Combustion 11

Comparison of SO2 Emissions between Air and Oxyfiring mode: Variation of temperature

0

50

100

150

200

250

300

350

400

450

500

650 700 750 800 850 900

SO

2[m

g/M

J BS]

Temperature[°C]

Oxy: Temperature vs. SO2

0

50

100

150

200

250

300

350

400

450

500

650 700 750 800 850 900

SO

2[m

g/M

J BS]

Temperature[°C]

Air: Temperature vs. SO2Air 2-3%O2

Air 3-4%O2Air 4-6%O2

4% O2 in fluegas,

230 kW, 62% Recycle

Rateno sorbent,

no O2 staging,

4% O2 in fluegas,

235 kW, no sorbent,

no air staging,

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

Economical aspects



Comparison of SO2 Emissions between Air and Oxyfiring mode: Variation of false air intake

863-895°C, 230 kW, no sorbentAir excess = 4% of O2 in dry flue gas, RR=62%

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

Economical aspects


71737577798183858789919395

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24

CO2, dry [%vol]

SO

2[m

g/M

J BS]

N2 dry [ %VOL]

Oxy: N2 vs. SO2


Gas Analy

sis

S1

0

2

4

6

8

10

12

650 750 850 950

Hei

ght

[m]

Temperature[°C]

Temperature profile

PL=100%

PL=80% S2=20%

Pl=83% S2=17%

0

2

4

6

8

10

12

0.8 0.9 1 1.1 1.2

Hei

ght

[m]

λLOCAL[-]

Oxygen excess profile

PL 100%

PL 85% ; S2 15%

PL 83% , S1 17%

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

Economical aspects



-20%

-32,1%

-42%

SO2 at Exit

+9,6%

+88,7%

+126%

0

50

100

150

200

250

300

350

400

0

2

4

6

8

10

12

14

16

18

0% 5% 10% 15%

SO

2[m

g/

MJ B

S]

NO

[m

g/

MJ B

S]

Ratio O2 S1 / Total O2

Oxy: Oxygen Staging (S1) vs. NO and SO2

Oxygen Staging

842-905°C, 248 kW, no sorbentOxygen excess = 4% of O2 in dry flue gas, RR=62%, 8%

of recirculated flue gas through secondary gas inlet

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

Economical aspects



Sorbents overview

SORTE Limestone Dolomite 460µm Dolomite 370µm Calciumhydroxide

Mean

particle size[mm] 0,7904 0,4678 0,3713 0,0677

Silicium [%MASS] 0,00210 1,0039 1,64300 0,00309

Aluminium [%MASS] 0,06608 0,2233 0,49730 0,09736

Iron [%MASS] 0,04540 0,4487 0,58010 0,06689

Calcium [%MASS] 35,99699 21,4750 22,35000 53,0407

Magnesium [%MASS] 0,05731 13,4650 13,57500 0,08444

Sulfur [%MASS] 0,00658 0,0002 0,01539 0,00969

Natrium [%MASS] 0,30561 0,1300 0,12000 0,45030

Kalium [%MASS] 0,00992 0,0571 0,30105 0,01465

Spurstoffe [%MASS] 0,22037 0,1591 0,46037 0,32471

*Rest [%MASS] 63,28962 63,0378 60,45779 45,99

Photo

Limestone

Ca(OH)2

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Pass

thro

ugh

[%m

ass]

Particle size [mm]

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

Economical aspects



Desulphurisation using limestone

855-870°C, 250 kW, Sorbent:LimestoneAir excess = 4% of O2 in dry flue gas, RR=62,5%,

No air or O2 staging

CO2=95%vol,dry

CO2=94,8%CO2=94,4%

CO2=86,8%

60%

65%

70%

75%

80%

85%

90%

95%

100%

0 2 4 6 8

η DES

OX[

%]

Ca/S Ratio[molCa/molS]

Oxy Air

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects



Analysis of cyclone/filter ash during desulphurization

855-870°C, 250 kW, Sorbent:LimestoneAir excess = 4% of O2 in dry flue gas, RR=62,5%,


Calcium

Calcium

Sulfur

Sulfur

0

5

10

15

20

25

30

0 1 2 3 4 5

[%M

ASS]

Ca/S ratio [molCa/molS]

Air/Oxy: Limestone (Cyclone 2)

Ca Luft

Ca Oxy

S Oxy

S Luft

Calcium

CalciumSulfur

Sulfur

0

5

10

15

20

25

30

0 1 2 3 4 5

[%m

ass]

Ca/S ratio [molCa/molS]

Air/Oxy: Limestone (Filter)

Ca LuftCa OxyS LuftS Oxy

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects



Desulphurization using Dolomite

855-870°C, 250 kW, Sorbent:LimestoneOxygen excess = 4% of O2 in dry flue gas, RR=62,5%,

No staging

60%

65%

70%

75%

80%

85%

90%

95%

100%

0 0.5 1 1.5 2 2.5 3 3.5

η DES

OX [%

]

Ca/S Sorbent Ratio [molCa/molS]

Air Dolomite 460

Air Dolomite 460

Oxy Dolomite 460

Oxy Dolomite 460

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects




855-870°C, 250 kW, Sorbent:LimestoneOxygen excess = 4% of O2 in dry flue gas, RR=62,5%,

No staging

60%

65%

70%

75%

80%

85%

90%

95%

100%

0 0.5 1 1.5 2 2.5 3 3.5

ηD

ESO

X[%

]

Ca/S Sorbent Ratio [molCa/molS]

Air Dolomite 460Air Dolomite 460Air Dolomite 370Oxy Dolomite 460Oxy Dolomite 460Oxy Dolomite 370Oxy Dolomite 370

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects




855-870°C, 250 kW, Sorbent:DolomiteOxygen excess = 4% of O2 in dry flue gas, RR=62,5%,


Calcium

Sulphur

0

5

10

15

20

25

0 1 2 3 4

[%]

Ca/S Verhältniss [molCa/molS]

Air/Oxy: Dolomite 460µm

Luft Ca

Luft S

Oxy Ca

Oxy S

Sulphur

Calcium

Calcium

Sulphur

0

5

10

15

20

25

0 0.5 1 1.5 2 2.5

[%]

Ca/S Verhältniss [molCa/molS]

Air/Oxy: Dolomite 370µm

Luft Ca

Luft S

Oxy Ca

Oxy S

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects



Desulphurization using Calcium Hydroxide Ca(OH)2

860-880°C, 248 kW, Sorbent:Ca(OH)2Air excess = 4% of O2 in dry flue gas, RR=62,5%,


Motivation




Behavior of SO2 undernormal conditions

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overwiew

(Economical aspects)


Oxy

Air

0.01

0.1

1

10

100

1000

400 500 600 700 800 900

Part

ial P

ress

ure

p H2O

[bar

]

Temperature [°C]

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

0 1 2 3

ηD

ESO

X [

%]

Ca/S Ratio [molCa/molS]

Oxy

Air

Replotted from: S.Lin, Y.Wang, Y.Suzuki: High Temperature CaO Hydration and

Ca(OH)2 Decomposition over a Multitude ofCycles, in Energy & Fuels 23,2009, Page

2856-2861


Overview of sorbents

60%

65%

70%

75%

80%

85%

90%

95%

100%

0 1 2 3 4

η DE

SOX[%

]

Ca/S [molCa/molS]

Air firing

Ca(OH)2Dolomite 460Dolomite 370Limestone

60%

65%

70%

75%

80%

85%

90%

95%

100%

0 2 4 6 8

ηD

ESO

X[%

]

Ca/S [molCa/molS]

Ca(OH)2Dolomite 460Dolomite 370Limestone

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects



Economy of Desulphurization

Sorbent €/t Airt/DayOxy

t/DayAir

€/DayOxy

€/DayCa(OH)2 80* 88 98 7.100 7.800

Limestone 20** 271 - 5.400 -

Dolomite 370µm

33*** 207 312 6.900 10.300

Dolomite 460µm

30** 235 413 7.100 12.400

Reference power Plant 460 MWeNet Plant Efficiency 43,3%Fuel used for experiments : 55,5 kg/s

Sources:* Walhalla Kalk GmbH

**sh Minerals AG***Ostrauer Kalkwerke GmbH

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects



Overview

Direct desulphurization in the combustion chamber forOxyfuel firing is still possible, but the efficiency is lower thanfor air firing

Effect of particle size distribution of sorbent is relatively high

Ca(OH)2 as an alternative sorbent probably too expensive

Air/O2 Staging is an disadvantage for sulfurisation reaction

Slight decrease of CO2 Concetration in Oxy-Modus boosts theeficiency of desulphurization

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects



Acknowledgement

Thank to our project partners and sponsors:

German Federal Ministry of Economic (COORETEC Programme)

Vattenfall

E.ON Energie AG

RWE Power AG

Linde AG

…and thankYou forYour attention!

Motivation




SO2 without sorbent

Sorbent Limestone

Sorbent Dolomite

Sorbent Ca(OH)2

Overview

Economical aspects


behavior of sulfur during circulating fluidized bed oxyfuel combustion · 2013. 9. 25. · behavior...

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