helsinki university of technology ene-47.153 sulphur #1

HELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153

SULPHUR #1SULPHUR #1•• IntroductionIntroduction•• SOxSOx emissions emissions•• SulphurSulphur species in fuel species in fuel•• SulphurSulphur compounds and combustion/ compounds and combustion/gasificationgasification•• Flue gas Flue gas desulphurisation desulphurisation (FGD):(FGD):

Wet dry , Wet dry , regenerable regenerable / non-/ non-regenerableregenerable•• In-duct In-duct sorbent sorbent injection (cold)injection (cold)•• Furnace / in-ductFurnace / in-duct sulphur sulphur injection (hot) injection (hot)•• Costs related to FGDCosts related to FGD

see: www.hut.fi/~see: www.hut.fi/~rzevenhorzevenho//gasbookgasbook

HELSINKI UNIVERSITY OF TECHNOLOGYHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153ENE-47.153

Sulphur emissionsSulphur emissions

Combustion of fuelsCombustion of fuels

for heat, power and transportfor heat, power and transport

Contribution from naturalContribution from natural

sources sources ((e.g.e.g. volcanoes) volcanoes)

Sulphur emissionsSulphur emissions

(H(H22S, SOS, SO22, SO, SO3 3 →→ acid rainacid rain))


Reasons for controlling SOReasons for controlling SO22 emissions emissions

•• SOSO22 contributes to acid rain contributes to acid rain

•• Health hazard (sulphate-containing aerosols) Health hazard (sulphate-containing aerosols)

•• H H22S (gasification) highly poisonousS (gasification) highly poisonous oxidation to SO oxidation to SO22


Sulphur emissions and depositions in Europe 1994Sulphur emissions and depositions in Europe 1994Density of SO2 emissions in 1994

Unit: tons of SO2

Depositions of sulphur in Europe,1994 Unit: mg sulphur (S)/m2


Sulphur in fuelsSulphur in fuels

• biomass fuels

• solid fuels ⇒⇒inorganic á pyritic sulphur (FeS2)á sulphates (Na2SO4, CaSO4, …)

⇒⇒organic á sulphides, mercaptanes, bisulphides, thiophenes, thiopyrones etc.

• natural gases / raw fuel gases á H2S

• unrefined oil / heavy fuel oils

á small amounts of sulphur

• waste-derived fuels

á e.g. vulcaniser, food-derived waste (garlic, onion), ”black liquor” etc.

⇒⇒organic á sulphides, mercaptanes, bisulphides


Sulphur in fuels - general valuesSulphur in fuels - general values

Coal: 0.2 - 5 %

Oil: 1 - 4 %

Natural gas: 0 - 10 %

Light fuel oil: < 0.5 %

Heavy fuel oil: < 5 %

Waste derived fuels: < 2 %

Black liquor solids: ~ 5 %

Wood: < 0.1 %

Bark: < 2 %

Peat: < 1 %

Car tyre scrap: ~ 2 %

Fuel-S →→ … →→ SO2

SO2 + ½O2 →→ SO3

Temp. > 1100 °C : thermal (homogeneous)

Temp. 500…800 °C : catalytically (V, Ni, Fe)(heterogeneous)

SO3 + H2O →→ H2SO4 sulphuric acid

Temp. < dew point → corrosion


Sulphur pollutants from combustionSulphur pollutants from combustion

(1) Fuel devolatilisation Fuel-S (s) + heat → H2S + Char-S (s)

(thermal degration)

(2) Char oxidation Char-S (s) + O2 → SO2

Char-S (s) + CO2 → COS

Char-S (s) + H2O → H2S

(3) Gas phase reactionsH2S + O2 → SO2

CO2 + H2S COS + H2OCO + H2S H2 + COSCOS + H2S CS2 + H2OCS2 C(s) + 2/x Sx (s)

(4) Sulphuric oxide formationSO2 + ½ O2 SO3

H2O + SO3 H2SO4


Formation of sulphur compounds duringcombustion and gasification

Sulphuric acid condensationSulphuric acid condensation



Typical sulphur compounds found in fuelsTypical sulphur compounds found in fuels

Heavy fuel oil combustion / gasificationHeavy fuel oil combustion / gasificationHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153

SOSO22 emission standards for EU emission standards for EU –– Solid Fuels Solid Fuels (directive 2001/80/EC)(directive 2001/80/EC)


P = plant size in MWthermal

P = plant size P = plant size in MWin MWthermalthermal

SOSO22 emission standards for EU emission standards for EU

–– Liquid and Gaseous Fuels Liquid and Gaseous Fuels (directive 2001/80/EC)(directive 2001/80/EC)




SOSO22 emission standards for waste (coemission standards for waste (co--) firing ) firing and cement plants for EU and cement plants for EU (directive 2000/76/EC)(directive 2000/76/EC)




CCcoco--firingfiring = (= (VVwastewaste . . CCwastewaste + + VVprocessprocess.C.Cprocessprocess)/( )/( VVwastewaste + + VVprocessprocess), V = exhaust volume ), V = exhaust volume

Options for sulphur emissions controlOptions for sulphur emissions control

åå Substitute the fuel Substitute the fuel

åå Fuel cleaning Fuel cleaning

åå Abatement techniques Abatement techniques

åå End-of-pipe control technologies End-of-pipe control technologies


åååå Physical methodsPhysical methods åååå inorganic sulphur (esp. pyritic sulphur, FeS inorganic sulphur (esp. pyritic sulphur, FeS22))

åååå based on gravity, flotation, agglomeration, flocculation based on gravity, flotation, agglomeration, flocculation åååå up to 90% up to 90%

åååå Chemical methodsChemical methods åååå inorganic and organic fuel sulphur inorganic and organic fuel sulphur åååå treatment with alkaline or caustic solutions treatment with alkaline or caustic solutions åååå oxidative leaching oxidative leaching åååå chlorinolysis with chlorine-based chemicals chlorinolysis with chlorine-based chemicals

åå Biological methodsBiological methods åååå Thiobacillus ferrooxidansThiobacillus ferrooxidans (FeS (FeS22)) åååå PseudomonasPseudomonas (organic sulphur) (organic sulphur)

Fuel CleaningFuel CleaningHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153

Fuel Cleaning - ”hydrodesulphurisation”Fuel Cleaning - ”hydrodesulphurisation”


End-of pipe technologiesEnd-of pipe technologies (1) (1)


•• FGD: for exampleFGD: for example–– wet scrubbing with lime, giving liquid by-productwet scrubbing with lime, giving liquid by-product

–– spray dry scrubbing with alkaline, giving solid by-productspray dry scrubbing with alkaline, giving solid by-product

–– regenerable sorbentregenerable sorbent processes: processes: Wellman Wellman-Lord, -Lord, MgOMgO

•• Dry methods with Dry methods with sorbent sorbent injection into furnace orinjection into furnace or

furnace outletfurnace outlet

•• FluidisedFluidised beds allow for beds allow for in situin situ sulphur sulphur capturecapture

•• Hot gas clean-up of fuel gas from Hot gas clean-up of fuel gas from gasificationgasification

End-of pipe technologiesEnd-of pipe technologies (2) (2)


•• HH22S:S:–– Claus process, Super-Claus processClaus process, Super-Claus process

–– Regenerable sorbentsRegenerable sorbents, , e.g.e.g. ZnO ZnO.TiO.TiO22

•• Combined Combined SOx SOx / / NOx NOx control:control:–– Sulphuric Sulphuric acid absorbed on active coalacid absorbed on active coal

–– Copper oxide processCopper oxide process

----------------------------------------------------------------------------------------------------------------------------------

•• By-productsBy-products–– Solid waste (spent lime and dolomite, gypsum)Solid waste (spent lime and dolomite, gypsum)

–– Elemental Elemental sulphur sulphur and/or and/or sulphuric sulphuric acidacid

HELSINKI UNIVERSITY OF TECHNOLOGY ENE-4J.153/Sulphur

An FGD unitAn FGD unit

FGD : system overviewFGD : system overviewHELSINKI UNIVERSITY OF TECHNOLOGYHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153ENE-47.153

Non-regenerablesystems

Non-regenerableNon-regenerablesystemssystems Regenerable SystemsRegenerable SystemsRegenerable Systems

åå Wet scrubbersWet scrubbers

åå Spray-dry scrubbers Spray-dry scrubbers

åå Dual-alkali Dual-alkali

åå Seawater Seawater

åå Walther Walther

ååBergbau-Forschung/UhdeBergbau-Forschung/Uhde

ååWellman-LordWellman-Lord

ååLinde-SOLINOXLinde-SOLINOX

ååSpray-dry scrubbersSpray-dry scrubbers

ååMgO ProcessMgO Process

Process Sorbent End/by - product

Wet scrubbers Lime / LimestoneLime / Fly ash

Gypsum, Calciumsulphate/sulphiteCalcium sulphate/sulphite/flyash

Spray-dryscrubbers

Lime Calcium sulphate/sulphite

Dual - alkali Primary: sodiumhydroxideSecondary: lime

Calcium sulphate/sulphite

Seawater Primary: seawaterSecondary: lime

Waste seawater

Walther Ammonia Ammonia sulphate

The most important FGD systems withThe most important FGD systems with

non-regenerable sorbentsnon-regenerable sorbents



FGD : Limestone scrubbing FGD : Limestone scrubbing -- Process schemeProcess scheme

Chemical reactions limestone scrubbing

CaCO3 (s) + H2O + 2SO2 →→ Ca2+ + 2HSO3- + CO2

CaCO3(s) + 2HSO3- + Ca2+ + H2O →→ CaSO3 �� 2H2O(s) + CO2

CaSO3 �� 2H2O(s) + ½O2 →→ CaSO4 �� 2H2O(s)

Chemical reactions lime scrubbing

CaO (s)+ H2O →→ Ca(OH)2 (s)SO2 + Ca(OH)2 (s) + H2O →→ CaSO3 �� 2H2O(s)CaSO3 �� 2H2O (s) + ½O2 →→ CaSO4 �� 2H2O(s)

å

å

FGD: Limestone / Lime scrubbingFGD: Limestone / Lime scrubbing


Lime / limestone scrubbing - optimum pHLime / limestone scrubbing - optimum pH


SO2 is absorbed in the water : SO2 + 2H2O H3O+ + HSO3

-

for limestone:CaCO3 goes into solution: CaCO3(s) + H3O

+ Ca2+ + HCO3-

CaSO3 is formed: Ca2+ + HSO3- + 3H2O

CaSO3. 2H2O(s) + H3O+

CO2 is released: H3O+ + HCO3

- CO2 + 2H2Ofor lime:

CaO goes into solution: CaO (s) + H2O Ca2+ + 2OH -

CaSO3 is formed: Ca2+ + HSO3- + 3H2O

CaSO3. 2H2O(s) + H3O+

water is formed: H3O+ + OH - 2H2O

FGD : Seawater systemsFGD : Seawater systems


To stack

Seawater scrubber

Watertreatment

plant

Lime

Air

Particlecollector

Effluent seawater

Condenser

Powerplant

Seawater

FLUEFLUE GAS GAS

FLUEFLUE GAS GAS

FGD : Dual-alkali processFGD : Dual-alkali processHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153

Thickener

Clean flue gas to stack

Chemistry of the dual-alkali processChemistry of the dual-alkali processin the scrubber :Na2SO3 + SO2 + H2O → 2NaHSO3

2NaOH + SO2 → Na2SO3 + H2O

in the precipitation tank :2NaHSO3 + CaO(s) → Na2SO3

NaHSO3 + CaO(s) → CaSO3 ⋅ 2H2O(s) + NaOHCaSO3 ⋅ 2H2O(s) + ½O2 → CaSO4 ⋅ 2H2O(s)

in the regeneration tank :NaHSO3 + Na2CO3 → Na2SO3 + NaHCO3

NaHSO3 + NaHCO3 → Na2SO3 + H2O + CO2

è

è

è


+ CaSO3 + H2O

Process Sorbent / principle End/by - product

Wellman - Lord Sodium sulphite (Na2SO3) Concentrated SO2

Bergbau Forschung /Uhde

Activated carbon Concentrated SO2

Linde SOLINOX Physical absorption Concentrated SO2

Spray-dry scrubbing Sodium carbonate (Na2CO3)

Elemental sulphur

MgO process Magnesium oxide (MgO) Concentrated SO2

TheThe most important FGD systems withmost important FGD systems with

regenerable sorbents regenerable sorbents


Regenerable SORegenerable SO22 control : Wellman-Lord control : Wellman-Lord


in the scrubber :Na2SO3+ SO2 + H2O → 2NaHSO3

Na2SO3 + ½O2 → Na2SO4

in the regenerator :NaHSO3 → Na2SO3+ SO2 + H2O

make-up soda or lime :Na2CO3 + SO2 → Na2SO3 + CO2

2NaOH + SO2 → Na2SO3 + H2O

in the gaseous product :SO2 + ½O2 + H2O → sulphuric acid

Chemistry of the Wellman-Lord FGDChemistry of the Wellman-Lord FGD


Fluidised bed copper oxide process:Fluidised bed copper oxide process:HELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153

simultaneous SOsimultaneous SO22/NOx remov/NOx removalal

absorber

~ 400°C

absorber

~ 400°C

heater

400 Õ 500 °C

heater

400 Õ 500 °C

regenerator

~ 500 °C

regenerator

~ 500 °C

Fluidised bed copper oxide processFluidised bed copper oxide processHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153

simultaneous SOsimultaneous SO22/NOx removal/NOx removal

Absorber:Absorber:CuO + SO2 + ½O2 Õ CuSO4

CuO + SO2 Õ CuSO3

CuO + SO3 Õ CuSO4

4 NO + 4 NH3 + O2 Õ 4 N2 + 6 H2O2 NO2 + 4 NH3 + O2 Õ 3 N2 + 6 H2OHeater / Regenerator:Heater / Regenerator:CuSO4 + ½CH4 Õ Cu + SO2 + ½ CO2 + H2OCuSO3 + 14 CH4 Õ Cu + SO2 + 14 CO2 + ½ H2OCuO + 14 CH4 Õ Cu + 14 CO2 + ½ H2O

Transport section:Transport section: Cu + ½O2 ÕCuO CuSO3 + ½O2ÕCuSO4

Off-gas treatment:Off-gas treatment: CH4 + 2 SO2 Õ 2/x Sx + 2 H2O + CO2

Quality specifications for FGD gypsumQuality specifications for FGD gypsum


Principle of in-duct sorbent injectionPrinciple of in-duct sorbent injectionHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153

CaO(s) + ½O2 + SO2 → CaSO4(s)CaO(s) + H2O → Ca(OH)2(s)

Ca(OH)2 (s) + SO2 → CaSO3 (s) + H2O

Dry systems Semi-dry systems

Temperature: 150 - 250ºC

Alstom PowerAlstom Power (earlier ABB Fläkt)(earlier ABB Fläkt) NID processNID process(New Integrated Desulphurisation)(New Integrated Desulphurisation)


Furnace sorbent injectionFurnace sorbent injection


SOSO22 removal at different temperatures for sorbent removal at different temperatures for sorbentinjectioninjection


SOSO22 capture via direct sorbent injection :capture via direct sorbent injection :TemperatureTemperature



Sulphur uptake by injected sorbent particlesSulphur uptake by injected sorbent particles

formation of CaOformation of CaOCaCOCaCO33 (s) CaO (s) + CO (s) CaO (s) + CO22

Ca(OH)Ca(OH)22 (s) CaO (s) + H (s) CaO (s) + H22OO

sorption reactionssorption reactionsCaO (s) + CaO (s) + ½½OO22 + SO + SO2 2 CaSO CaSO44 (s) (s)CaO (s) + SOCaO (s) + SO3 3 CaSO CaSO44 (s) (s)CaO (s) + 2HCl CaClCaO (s) + 2HCl CaCl22 (s) + H (s) + H22OO

SOSO22 removal at different temperatures for sorbent removal at different temperatures for sorbentinjectioninjection


FGD : The LIFAC Process (Fortum, Finland)FGD : The LIFAC Process (Fortum, Finland)



A LIFAC unit (USA)A LIFAC unit (USA)


Costs of FGD processesCosts of FGD processes (1995 US$/(1995 US$/tonnetonne SO SO22))

Plantsize,

MWelecelec

Coalsulphurcontent,

%

FGD process FixedO & M

VariableO & M

Fixedcapitalcharge

Totalcosts

200 2.6 Wet limestone scrubber* 79 90 183 352

200 2.6 Spray dry scrubber** 40 143 134 317

200 2.6 Lurgi CFB*** 15 140 123 277

500 4.3 Wet limestone scubber 20 76 83 178

500 4.3 Spray dry scrubber 11 131 69 211

500 4.3 Lurgi CFB 3 130 63 196

helsinki university of technology ene-47.153 sulphur #1

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