third app oxy- - university of newcastle · fluidized bed oxy-fluidized bed oxy ---fuel combustion...

Fluidized bed OxyFluidized bed OxyFluidized bed OxyFluidized bed Oxy----fuel combustion and CCSfuel combustion and CCSfuel combustion and CCSfuel combustion and CCS

Third APP OxyThird APP OxyThird APP OxyThird APP Oxy----fuel Capacity Building Coursefuel Capacity Building Coursefuel Capacity Building Coursefuel Capacity Building CourseYeppoon, Queensland

September 2011

SankarSankarSankarSankar BhattacharyaBhattacharyaBhattacharyaBhattacharyaAssociate Professor

Department of Chemical Engineering

Energy, Fuels and Reaction Engineering Research GroupEnergy, Fuels and Reaction Engineering Research GroupEnergy, Fuels and Reaction Engineering Research GroupEnergy, Fuels and Reaction Engineering Research GroupOur focus:Scientific R&D for Practical Solutions

Contents of the presentationContents of the presentationContents of the presentationContents of the presentation


• Coal-fired power generation – current status

• Circulating fluidised bed (CFB) combustion• current status• characteristics• advantages

• Oxy-CFB• current status• charasteristics• advantages• CCS implications and development needs

Concluding comments

CoalCoalCoalCoal----fired power generation capacityfired power generation capacityfired power generation capacityfired power generation capacity


Global Installed Capacity (Mwe)

Regional distribution of Coal-fired power plants

1651858

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

ASIA AFRICA ANZ

OCENIA

RUSSIAN

CONTINENT

EUROPE LATIN

AM ERICA

NORTH

AM ERICA

M IDDLE

EAST

TOTAL

MWe

Global Installed Capacity (MWe)

Operational Coal-fired power plants

56

6,1

46

26

8,5

47

27

5,6

26

26

6,7

47

22

9,4

08

45

,38

4

1,6

51

,85

8

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

≤10 Years 11-20

Years

21-30

Years

31-40

Years

>40 Years Unknown

age

TOTAL

MWe

Global CoalGlobal CoalGlobal CoalGlobal Coal----fired power generation fired power generation fired power generation fired power generation capacitycapacitycapacitycapacity

• ~ ~ ~ ~ 1650 GWe at the end of 2010

Source: Platts, 2011

Circulating fluidised bed (CFB) combustionCirculating fluidised bed (CFB) combustionCirculating fluidised bed (CFB) combustionCirculating fluidised bed (CFB) combustion


0

5,000

10,000

15,000

20,000

25,000

≤100MWe 101-200 MWe 201-300 MWe 301-400 MWe 401-500 MWe >500 MWe

≤10 Years 11-20 Years 21-30 Years 31-40 Years >40 Years Unknown age

Operating Circulating Fluidised Bed Power Plants

Installed Capacity (MWe)

Operating Circulating Fluidised Bed Power Plants

Regional distribution (MWe)

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

ASIA AFRICA ANZ

OCENIA

RUSSIAN

CONTINENT

EUROPE LATIN

AM ERICA

NORTH

AM ERICA

M IDDLE

EAST

Installed Capacity, MWeGlobal CFB capacityGlobal CFB capacityGlobal CFB capacityGlobal CFB capacity

• 46.5 GWe at the end of 2010

• 17 GWe at the end of 2004

• fuels – anthracite to lignite, biomass, pet coke

Source: Platts, 2011

What is CFB combustionWhat is CFB combustionWhat is CFB combustionWhat is CFB combustion


SecondaryAir

Air, fuel, sorbent feed Aeration

air

Ash/ bed material

CharacteristicsCharacteristicsCharacteristicsCharacteristics

• Low operating temperature, around 900°C, relative to pulverized coal combustion

• Bed materials and coal/char particles circulating throughout the furnace and return leg at high velocity, 3-8m/sec

•Longer residence time of the circulating solids

• Lower excess air relative to pulverized coal combustion

• Staged combustion

Efficiency of CFBC units is similar to pulverized coal-fired units under identical steam conditions

ExternalHeatExchanger

Advantages of CFB combustionAdvantages of CFB combustionAdvantages of CFB combustionAdvantages of CFB combustion


• Low operating temperature, around 900°C, relative to pulverized coal combustion, low NOx

• Fuel flexibility – from high to low-grade fuels, biomass and opportunity fuels

• Uniform heat flux

• Excellent load-following capability

• In-situ sulphur dioxide capture rather than flue gas desulphurisation as in pulverized coal combustion, and

higher calcium utilization

• Lower NOx formation relative to pulverized coal combustion due to lower operating temperature

• Compact boiler size

• Simplified fuel feeding, pulverization is not required, crushing is sufficient

• Ideal for Oxy-fuel CCS

Schematic of a CFB combustion pilot plantSchematic of a CFB combustion pilot plantSchematic of a CFB combustion pilot plantSchematic of a CFB combustion pilot plant

cyclone

externalheat

exchanger

combustor

coalfeeder

additivefeeders

screwconveyor

bedmedia

removal

fluidisingair

natural gas

electric air heater

convectionsection

heatexchanger

mediaremoval

primaryair

secondaryair

PD blower

convection sectioncooling fan

ID fan

stack

flue gascooling fan

air

combustorair heater

fabricfilter

fluegas

coolers(three)

fly ashdischarge

to stack

Used for First Used for First Used for First Used for First ----of of of of ----its its its its ----kind trials in Australia using high moisture and high /low ash kind trials in Australia using high moisture and high /low ash kind trials in Australia using high moisture and high /low ash kind trials in Australia using high moisture and high /low ash ligniteslignitesligniteslignites


Chronology of CFB ScaleChronology of CFB ScaleChronology of CFB ScaleChronology of CFB Scale----upupupup


Source: Utt, 2008; Business Wire, 2011

• Largest operating – 460 MWe, supercritical steam parameter, unit at Lagisza• Recently awarded – four 550 MWe, supercritical steam parameter, units in Korea

• Designs up to 800 MWe available

Oxy CFB Oxy CFB Oxy CFB Oxy CFB –––– introduction and simplified schematicintroduction and simplified schematicintroduction and simplified schematicintroduction and simplified schematic


Mixer

Recyclefan

ASU

N2/Ar

O2

95-97%

Air

Gas purificationCO2 compression

Secondarygas

Fuel and sorbent feed

Ash/ bed material

CO2 to storage/use

Impurities

Inerts

Dust collectorPreheater

Convection section

• variant of air-CFB • fluidization and combustion by mix of oxygen and recycled flue gas• bed and gas temperatures to the same level in an air-fired CFB unit• reduces recirculation of flue gas due to recirculating solids in the riser-loop

Ash

Oxy CFB Oxy CFB Oxy CFB Oxy CFB ---- advantagesadvantagesadvantagesadvantages


• Strong mixing in the furnace and long residence time due to recirculation of solids allow

high carbon burnout; clearly suits low-reactive coals

• Recirculation of the cooled solids from the external heat exchanger allow a Oxy-CFB

boiler to operate with lower flue gas recycling compared to Oxy-PF systems

• Reduction of flue gas recycling, thereby reducing the size of the boiler island, and some of

the auxiliaries consumption. This may potentially allow more compact and less expensive

CFB boilers

• Direct sulfation of limestone will occur due the high partial pressure of CO2 and the right

thermodynamic temperature for sulfur capture; calcium conversion under direct sulfation is

usually higher than that under calcination/sulfation due to the better porosity of product layer

Oxy CFB Oxy CFB Oxy CFB Oxy CFB ---- advantagesadvantagesadvantagesadvantages


• Fans and blowers consume less power as the draft system handles higher molecular

weight gas

• Oxygen concentration in the recycled flue gas can be kept to a low and safe level, while

additional oxygen can be introduced through oxygen nozzles separate from the burner or the

secondary gas inserting points.

•Transition from air-mode combustion to oxy-mode combustion is potentially easier relative

to oxy-PF, because CFB has large amount of inert bed material that also helps in controlling

the bed temperature.

• CFBC’s operated at slightly over atmospheric pressure, possibility of air-in-leakage is

greatly reduced.

Oxy CFB Oxy CFB Oxy CFB Oxy CFB ---- developmentsdevelopmentsdevelopmentsdevelopments


2015

Oxy-fired

CIUDEN

COMPOSTILLA

Adapted from Utt, 2008

Air-fired CFB

• first Oxy-CFB development started in 1986!

Major OxyMajor OxyMajor OxyMajor Oxy----CFB Facility CFB Facility CFB Facility CFB Facility ---- CIUDENCIUDENCIUDENCIUDEN


• first ever integrated facility

Major OxyMajor OxyMajor OxyMajor Oxy----CFB Facility CFB Facility CFB Facility CFB Facility –––– CIUDEN boilerCIUDEN boilerCIUDEN boilerCIUDEN boiler


Source: Lupion, 2010

Smaller OxySmaller OxySmaller OxySmaller Oxy----CFB FacilitiesCFB FacilitiesCFB FacilitiesCFB Facilities


VTT facility (0.1 MWth) CANMET facility (0.8 MWth)

OxyOxyOxyOxy----CFB CFB CFB CFB –––– development issuesdevelopment issuesdevelopment issuesdevelopment issues


Coal Qualityissues

Gas Cleaning/Impurityremoval

ASU-Cost of O2

generation

Boilerdesignissues

IntegratedOperation/ controlissues

Overalleconomics

Integrated demonstration necessaryIntegrated demonstration necessaryIntegrated demonstration necessaryIntegrated demonstration necessary

MaterialIssues –Gas environment

Oxy CFB Oxy CFB Oxy CFB Oxy CFB –––– coal qualitycoal qualitycoal qualitycoal quality issues related to its developmentissues related to its developmentissues related to its developmentissues related to its development


Mixer

Recyclefan

ASU

N2

O2

Air

Gas purificationCO2 compression

Heat transfer

Emissions from the riser

superheater

economiser

Unburnt carbon / lime

BedAgglomeration

Fouling

Recarbonation

Sulfur capture

Trace metal emission

Unburnt carbon

Oxy CFB Oxy CFB Oxy CFB Oxy CFB –––– coal qualitycoal qualitycoal qualitycoal quality issues issues issues issues –––– results so farresults so farresults so farresults so far


Heat transferHeat transferHeat transferHeat transferDepends on solids effects, not on gas compositionNo major issues on all types of coals

Coal Coal Coal Coal devoldevoldevoldevol & & & & ignition delayignition delayignition delayignition delay

No significant issues on all types of coals

Gaseous emissionGaseous emissionGaseous emissionGaseous emission

CO somewhat higher; High CO2 hinders CO oxidationNOx lower; NH3 injection further reduced NOx

emissionIn-bed SOx capture possible and better than inAir-CFB, however further tests necessary

Trace elementTrace elementTrace elementTrace elementemissionemissionemissionemission

Least known;For some bituminous coals – Hg and major trace metal emission same as in air-CFB combustion; modeling suggests the sameFurther investigation necessary for a wide range of coalsSource: Bithi Roy et al., 2011



RecarbonationRecarbonationRecarbonationRecarbonation

Evidence of recarbonation with some bituminous coalsLittle known for coals with high Ca contentSystematic investigation necessary for a wide range of coals

FoulingFoulingFoulingFouling

No evidence with some bituminous coalsSystematic investigation necessary for a wide range of coals

S S S S ---- transformationtransformationtransformationtransformation

For some bituminous coals – in bed capture is higher than in air-CFB combustionOverall higher Ca-utilisation, supported by modelingHowever, SO3 emission is higherFurther investigation necessary for a wide range of coals having different types of S (organic/inorganic)



Bed agglomerationBed agglomerationBed agglomerationBed agglomeration

No evidence with bituminous coals or pet coke;Could be issues with lignites containing alkali, calcium, sulfur and chlorine; modeling suggests increased agglomeration;Further investigation necessary with such coals

650 µµµµm14 0µµµµm

60 µµµµm

h61

1

2

3

4

Source: Bithi Roy et al., 2011

Oxy CFB Oxy CFB Oxy CFB Oxy CFB –––– materials and boiler design issuesmaterials and boiler design issuesmaterials and boiler design issuesmaterials and boiler design issues


• Same issues as in Oxy-pf combustion• different combustion atmosphere – high CO2 and H2O vapour• also CO, H2S, SO2, SO3, HCl• however temperatures are lower• environment is much more abrasive from the recirculating solids

• Burner design unlikely to be significantly different from air-CFB

Oxy CFB Oxy CFB Oxy CFB Oxy CFB –––– air separation issuesair separation issuesair separation issuesair separation issues

• Same developmental issues as in Oxy-pf combustion• oxygen purity issues and subsequent effect on CO2 quality same as in Oxy-pf

Oxy CFB Oxy CFB Oxy CFB Oxy CFB –––– gas cleaning issuesgas cleaning issuesgas cleaning issuesgas cleaning issues


• Similar issues as in Oxy-pf combustion• limited information on release of Hg and trace metals on a range of coals under oxy-CFB condition • the recirculating char and the flyash is likely to carry these species eventually to the bed discharge and bag filter

• fundamental experimental work necessary to establish the extent of emission of Hg, S-species, and trace metals in oxy-CFB condition compared to air-CFB condition

• Sealing of the boiler and air in-leakage• CFB boilers are usually operated under slight overpressure, 20-40” water gauge• this is likely to minimize air-ingress into a properly maintained Oxy-CFB boiler

.

Major Retrofit needs for COMajor Retrofit needs for COMajor Retrofit needs for COMajor Retrofit needs for CO2222 capture in an aircapture in an aircapture in an aircapture in an air----CFB unitCFB unitCFB unitCFB unit


• Case by case study needed• Heat fluxes and heat transfer areas can largely be matched

• New equipment for the CFB boiler• new gas recirculation system• oxygen supply piping• CO2 product ductwork• gas processing system• new control and instrumentation system

• Air separation unit

• New space for the new equipment

Concluding commentsConcluding commentsConcluding commentsConcluding comments


• Air-CFB advantages also exist in Oxy-CFB• Low furnace temperatures• Long solid residence times• Hot recirculating solids• Uniform heat flux and efficient heat transfer

• Fuel flexibility• Good fuel burnout and S-sorbent utilization• NOx and SOx reduction without flue gas desulfurization• Simple feed systems

• Ability to operate in air-firing or oxy-fuel mode for CCS• 90% CO2 in off-gas at 3% O2 level can potentially be achieved• Reduced boiler size

• Demonstration at CIUDEN is critical to:• Identify research and development issues – fuel/gas processing/materials• Gain experience on stable operation• Minimise cost and cost uncertainty – for new and retrofits

Innovation : Chemical Looping CycleInnovation : Chemical Looping CycleInnovation : Chemical Looping CycleInnovation : Chemical Looping Cycle


Airreactor

Fuelreactor

MeO (+ Me)

Me (+ MeO)

N2, O2 CO2, H2O

Fuel Air

air

flue gas

bleed

COfuel noncondensible

gas

H O2

2

1

3

2

1 – CFB riser2 – Cyclone3 – Heat exchangerLonger-term : extended from CFB experience

BibliographyBibliographyBibliographyBibliography


• E. J. Anthony and L. Jia. Agglomeration and strength development of deposits in CFBC boilers firing high-sulfurfuels. Fuel 2000;79:1933-1942

• T Eriksson et al., Development of Flei-Burn CFB technology aiming at fully integrated CCS demonstration, PowerGenEurope, 2009

• A. Hotta, Foster Wheeler’s solutions for large scale CFB boiler technology, Proc of the 20th Int Conf on Fluidized bed combustion, 2009

• L Jia, Y Tan, C Wang, and E. J. Anthony, Experimental study of oxy-fuel combustion and sulphur capture in a miniCFBC, Energy & Fuels, 21, 2007

• M Lupion, 2nd APP Oxyfuel Capacity Building Course, March 2010

• G Özkan and G Dogu. Combustion of a high ash and sulfur containing lignite in a pilot circulating fluidized bed combustor and its pollution characteristics. Chemical Engineering and Processing 2002;41:11-15.

• A Robertson, S Goidich, Z Fan, 1300F 800 MWe USC boiler design study, Proc of the 20th Int Conf on Fluidized bed combustion, 2009

• B Roy, WL Choo, S Bhattacharya, Prediction of selective trace element emissions during Oxy-CFB combustion of Victorian brown coals, , ICCST, 2011

• B Roy, WL Choo, L Chen, S Bhattacharya,thermodynamic modeling of agglomeration during oxy-CFB combustion of Victorian brown coal, Chemeca 2011

• C S. Zhao, L. B. Duan, X. P. Chen, and C. Liang. Latest evolution of Oxy-fuel combustion technology in circulating fluidized bed. Proc of the 20th Int Conf on Fluidized Bed Combustion, 2009.

• World Electric Power Plants database, Platts, 2011

third app oxy- - university of newcastle · fluidized bed oxy-fluidized bed oxy ---fuel combustion...

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