The Sulphur Mass Balance in Oxy-Fuel Combustion of ...
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Chalmers University of Technology
The Sulphur Mass Balance in Oxy-Fuel Combustion
of Ligniteof Lignite-
An experimental studyD. Fleig, K. Andersson, D. Kühnemuth, F. Normann, F. Johnsson, B. Leckner
Division of Energy Technology, Department of Energy and Environment, Chalmers University of Technology, Göteborg, Sweden
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
y f gy g
Chalmers University of Technology
IntroductionIntroduction-
Aims of the work
• Quantify sulphur sinks
• Are there differences in sulphur chemistry between air and oxy-fuel combustion?y
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Motivation of the workL d SO i i i lit t• Lowered SO2 emissions in literature
• Design of the flue gas cleaning• Sulphur self-retention of the ash• SO2 concentration influences corrosion2
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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ExperimentsExperiments-
Chalmers 100kW oxy-fuel test unit
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Schematic of the test unit
Pre-heater
(Air)O2
Stack
s
Dry flue gas recycle
T
Fuel
TOxidiser
urna
ce
Wet
flue
gas
recy
cle
TT
T
TTFlue gas cooler
Fabricfilter
Flue gas condenser
CycloneFu
GasBottom CoolerCyclone Filter CondenserGassample
Bottom ash
Cooler ash
Cyclone ash
Filter ash
Condenser water
SO2, CO2
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O2 and CO
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Sulphur mass balance
Gassample
Fuel Cooler ash
Cyclone ash
Filter ash
Condenser water
Bottom ash
Sulphur mass balance:
sampleashash ash waterash
Sulphur ash mass flow:p
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Determination of S-flows
weighed
measuredSulphur ash flows:
(balance)
calculatedcalculated
sulphur mass concentration
Residual ash flow: Fuel ash flow
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Determination of S-flowsSulphur flue gas flow:Sulphur flue gas flow:
Conversion of fuel-S to SO2
Sulphur fuel flow:
Sulphur water flow:
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Test cases
• Air fired case• Dry oxy fuel case OF35• Dry oxy-fuel case OF35• Wet oxy-fuel case OF43w
Roughly same max. temperatures
In all test cases: • Predried Lausitz lignite 13kg/h, 76kW
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Fuel analysis (Lausitz lignite)
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Results-
Conversion to SO2 / SO2 concentrations
m (d
ry)
wet
)
pm (d
ry)
t)
2 2
ry)
t) 1870
ppm
600
ppm
(w
1960
pp
ppm
(wet
0 pp
m (d
r p
pm (w
et 16
1300
550
500
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Ash flows / S-concentrationsAsh flows
9-15% S 8-17% S 10-18% S
3.0% S 3.6% S 3.7% S
6.6% S 6.5% S 6.8% S
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
Chalmers University of Technology
Sulphur flow in ash
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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S l h AirSulphur mass balance
OF35
OF43OF43wSulphur mass flow in the fuel is set to 100%
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
is set to 100%
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ConclusionsL d i i f SO b it i• Lowered emission of SO2 by unit energy in oxy-fuel combustion compared to air firing
• More than 3 times higher SO2 concentrations in the flue gas from oxy-fuel combustion
• Sulphur mass flow in the ash is higher in oxy-fuel compared to air firing
• Sulphur mass flow in condenser water is low
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
Chalmers University of Technology
Ongoing work and future workCl if th i th b l• Clarify the gap in the mass balance
• Parameter studie SO2 emissions• Limestone + lignite• SO3 measurements3
• Particle sampling from the combustion zone
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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Vattenfall AB is acknowledged forVattenfall AB is acknowledged for financial support
Thank you for your attention!y y
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
Chalmers University of Technology
Sulphur balanceH SO Conden-
SO3
H2SO4 sation
Sulphur in fuel
Sulphides(FeS )
SO3
Reactionswith ash toNa2SO4 K2SO4,
Sulphur in fuel
(FeS2) sulphates
SO2
2 4 2 4,CaSO4, MgSO4
Organic compounds SO2 and
0 1 5% SO0,1…5% SO3
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Fate of sulphur during coal combustion weiss nicht ob das mit
soll/kannS l h i lsoll/kann• Sulphur in coal:– Pyrite (FeS2), organically bound sulphur,...
• Combustion– Gases: SO2, SO3, H2S,...– Sulphur in ash:
• Not converted• Caputred (sulphates)
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DiscussionL i f f l S t SO• Lower conversion of fuel-S to SO2
Higher sulphur ash mass flowsPossible reason:SO2 concentration affect the ash selfSO2 concentration affect the ash self
retention
• However a higher difference in oxy-fuelDifficult at do sulphur mass balance
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Difficult to get residual ash samplesCyclone wirkungsrad war niedriger
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SO ith NDIR i t t (NGA 2000)
Sulphur mass balance• SO2 with NDIR instrument (NGA 2000)• Ash amount
– Bottom and cyclone ash were weighed– Residual ash by difference
• Sulphur in ash and fuel– Standdard method SS 187177
Durch diese Sachen schnelldurchgehen.
• Sulphur in condenser waterSolubilize with nitric acid ICP-OES i d ti l l d– Solubilize with nitric acid ICP-OES inductively coupled plasma - optical emission spectrometer
1st Oxy-fuel Combustion Conference, Cottbus , 8th -11th September 2009