The Sulphur Mass Balance in Oxy-Fuel Combustion of ... 5_A/Cottbus Daniel Fleig.… · The Sulphur...

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


IntroductionIntroduction-

Aims of the work

• Quantify sulphur sinks

• Are there differences in sulphur chemistry between air and oxy-fuel combustion?y



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



ExperimentsExperiments-

Chalmers 100kW oxy-fuel test unit



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


O2 and CO


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



Determination of S-flows

weighed

measuredSulphur ash flows:

(balance)

calculatedcalculated

sulphur mass concentration

Residual ash flow: Fuel ash flow



Determination of S-flowsSulphur flue gas flow:Sulphur flue gas flow:

Conversion of fuel-S to SO2

Sulphur fuel flow:

Sulphur water flow:



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



Fuel analysis (Lausitz lignite)



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



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



Sulphur flow in ash



S l h AirSulphur mass balance

OF35

OF43OF43wSulphur mass flow in the fuel is set to 100%


is set to 100%


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



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



Vattenfall AB is acknowledged forVattenfall AB is acknowledged for financial support

Thank you for your attention!y y



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


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)



Sulphur release, laboratory conditions


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


Difficult to get residual ash samplesCyclone wirkungsrad war niedriger


Sulphur release, laboratory conditions


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



Sulphur release from ashesSulphur release from ashes, laboratory conditions

The Sulphur Mass Balance in Oxy-Fuel Combustion of ... 5_A/Cottbus Daniel Fleig.… · The Sulphur...

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