Chalmers University of Technology The Sulphur Mass Balance in Oxy-Fuel Combustion of Lignite of Lignite - An experimental study D. Fleig, K. Andersson, D. Kühnemuth, F. Normann, F. Johnsson, B. Leckner Division of Energy Technology, Department of Energy and Environment, Chalmers University of Technology , Götebor g, Sweden 1 st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
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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
Chalmers University of Technology
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
Chalmers University of Technology
ExperimentsExperiments-
Chalmers 100kW oxy-fuel test unit
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
Chalmers University of Technology
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
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
O2 and CO
Chalmers University of Technology
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
Chalmers University of Technology
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
Chalmers University of Technology
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
Chalmers University of Technology
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
Chalmers University of Technology
Fuel analysis (Lausitz lignite)
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
Chalmers University of Technology
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
Chalmers University of Technology
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
Chalmers University of Technology
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%
Chalmers University of Technology
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
Chalmers University of Technology
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
1st Oxy-fuel Combustion Conference, Cottbus , 8th -11th September 2009
Chalmers University of Technology
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)
1st Oxy-fuel Combustion Conference, Cottbus , 8th -11th September 2009
Chalmers University of Technology
Sulphur release, laboratory conditions
Chalmers University of Technology
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
1st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009
Difficult to get residual ash samplesCyclone wirkungsrad war niedriger
Chalmers University of Technology
Chalmers University of Technology
Sulphur release, laboratory conditions
Chalmers University of Technology
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
Chalmers University of Technology
Sulphur release from ashesSulphur release from ashes, laboratory conditions