lecture 4: fluidised bed oxyfuel boilers and ccs -...
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Lecture 4: Fluidised Bed
Oxyfuel Boilers and CCS
Monica Lupion
CO2 Capture Programme
CIUDEN
Second APP Oxy-fuel Capacity Building Course
Beijing, 15th March 2010
Introduction to OxyCFB
Features of CFB
Supercritical CFB
CIUDEN and OxyCFB technology
• Combustion technologies Overview
• Comparison PC-FB Boilers
• Comparison CFB-BFB Boilers
• Historical Perspective
• CFB Hydrodinamics
• Combustion in CFB Boilers
Content
OxyCFB
• Supercritical Steam Parameters
• Lagisza OTU Supercritical CFB Plant
• Introduction
• Challenges
• Emissions in OxyCFB
• CIUDEN OxyCFB Boiler
• OXYCFB300 Project
Combustion technologies
Coal
Combustion
Fixed Bed
Pulverised Coal-PC
Fluidized Bed
PressurisedFluidized Bed
BubblingBFBC
CirculatingCFBC
Supercritical
Subcritical
Ultra-Supercritical
Combustion technologies
SUBCRITICAL PC SUPERCRITICAL PC ULTRASUPERCRITICAL PC
SUBCRITICAL CFB
Performance WOC WC WOC WC WOC WC WOC WC
Efficiency (HHV)
34.3 25.1 38.5 29.3 43.3 34.1 34.8 25.5
CO2 emited (g/KWh)
931 127 830 109 738 94 1030 141
COE 4.84 8.16 4.78 7.69 4.69 7.34 4.68 7.79
Performance and economics for air-blown PC generating
technologies
Basis net output: 500 MWe, 61.2% wt C, HHV=25350 kJ/kg
Adapted from The Future of Coal, Massachussetts Institute of Technology
45%
PC / FB Boilers
Characteristics Bubbling Circulating Pulverized
Height of the bed (m) 1-2 10-30 27-45
Superficial velocity (m/s) 1.5-2.5 3-5 4-6
Excess air (%) 20-25 10-20 15-30
Coal size (mm) 6-0 6-0 <0.1
Combustion efficiency (%) 90-96 95-99.5 99-99.5
NOx (ppm) 300-400 50-200 400-600
SO2 capture in furnace (%) 80-90 80-90 None
Comparison of PC and FB Boilers
Advantages of FB Boilers
• Low average heat flux: furnace tubes safer and more resilient to operational upsets
• Lower peak heat flux, different locationIn PC near the most vulnerable point (water to steam)In CFB where the water is just heated
Advantages of FB Boilers
Height (%Total)
Heat F
lux (
% P
C m
ax)
CFB
Fuel Flexibility
Better gas-solid mixing and higher burning rateHigh Combustion
Efficiency
• Staged addition of comburantLower NOx Emissions
• Higher sulfur capture capability of CFB: larger specific area of sorbents and longer residence time
In Situ Sulfur Removal
Smaller Grate Area
Good load-following capability
• Higher sugerficial gas velocity: Smaller grate area (furnacegrate area 2 to 3 times smaller than BFB)
• High fluidizing velocity and easy control: Quick response
CFB / BFB BoilersAdvantages of CFB Boilers
BFB needs to adjust heat absorption by number of tubesinmersed in the bed: LIMITED FLEXIBILITY
Historical Perspective of CFB
Beginning of FB
Firstexperiences
with CFB
CFB at Commercial
scale
- 1921. Fritz Winkler: Fluidization
- 1938. W Lewis & E Gilliland: CFB
- 60’s. Lurgi: cementindustry
- 80’s. 1st CFBB: 84 MW (9MW electricity)
- Ahlstrom.15 MW
- 2005. AirCFB Lagisza
- 1986. Berry and WolskyFirst OxyCFB with FGR
- 2015. OXYCFB300
In South East Asia
No. of UnitsTotal Capacity
(MW)
Historical Perspective of CFBCFB Plants by Manufacturer
In the World
No. of UnitsTotal Capacity
(MW)
Foster Wheeler
Alstom
21324,526
647,760
12010,193
243,076
About 500 CFB units around the world
•Over 170 CFB units in the US
•Over 350 CFB units in China
Unit Capacity (MWe)
0
100
200
300
400
500
600
1970 1975 1980 1985 1990 1995 2000 2005 2010
Start-Up Year
Pilot PlantOriental Chem
Lagisza
JEA
Turow 1
Vaskiluodon
Nova ScotiaTri-State
General Motors
2015
CIUDEN TDP
Jamestown
CompostillaAIR-FIRED
OXY-FIRED
Pilot Plant
Historical Perspective of CFBEvolution of CFB Unit Capacities
CFB Hydrodinamics
Property Packed bed Fluidizedbed
Fast bed PneumaticTransport
Application in boilers Stoker Fired BFB CFB PC
Mean particle diameter(mm)
<300 0.03-3 0.05-0.5 0.02-0.08
Gas velocity (m/s) 1-3 0.5-2.5 4-6 15-30
Solid-solid mixing Negligible Near perfect Near perfect Small
Overall voidage 0.4-0.5 0.5-0.85 0.85-0.99 0.98-0.998
Temperature gradient Large Very small Small Maybesignicant
Comparison of Gas-Solid Contacting Processes
Component Regime
Furnace (below secondary air level) Turbulent of BFB
Furnace (above secondary air level) Fast fluidized bed
Cyclone Swirl flow
Return leg (Standpipe) Moving packed bed
Loope seal/external heat exchanger BFB
Back-pass Pneumatic transport
Flow regimes in the components of a CFB
CFB Hydrodinamics
Supercritical CFB TechnologySteam Parameter
Steam Parameter
Change in boiler cost (%)
Change in Investment
cost (%)
Efficiency increase (%)
Change in CoE (%)
265 bar, 535ºC/571ºC
Reference Reference Reference Reference
265 bar, 583ºC/601ºC
+4.6 +0.2 1.9 -0.7
290 bar, 603ºC/621ºC
+9.5 +1.6 3.5 -0.7
Adapted from Laffont et al, PowerGen-Europe
At Lagizsa the SC-CFB firing option was found to be 20% cheaper in capital cost and 0.3% higher in net efficiency than SC-PC
Supercritical CFB TechnologyLagizsa OTU CFB Plant
• Location: Poland (PKE)• 460 MWe (gross) supercritical OTU-CFB
World’s largest single CFB UnitWorld’s first supercritical CFB
• NTP: Dec 05• Hand over: June 09• FW providing boiler island
Design Parameters
Fuel Bituminous coal
Plant efficiency
45.3% Gross43.3% Net
Design Steam Parameters at 100% load
SH Flow 361 kg/s
SH Pressure 275 bar
SH Temperature 560 ºC
RH Flow 306 kg/s
RH Pressure 54.8 bar
Cold RH Temperature 315 ºC
Hot RH Temperature 580 ºC
Emission (6% O2, dry)
SO2 200 mg/Nm3
NOx 200 mg/Nm3
Particulates 30 mg/Nm3
•BENSON vertical OTU tech licensed by Siemens AG (GE)
•Integrated steam cooled solids separators
•INTREXTM superheaters
•Furnace dimensions
- 27.6m x 10.6m
- 48 m height
Oxy-CFB
Oxyfuel
CFB
Technicallyviable
Challenges!
OxyCFB Technology
The established CFB advantages also exist in oxy
• Fuel Flexibitily
• Low NOx
• In bed SO2 capture
• Efficient heat transfer and uniform heat flux
Further potential
• CO2 capture
• Reduce boiler size
OxyCFB Technology
Coal and
limestone
OxyCFB TechnologySimplified diagram
Cooling – 53.5%
Auxiliaries
2.4%
Air Separation
7.0%
CO2 Compression
3.7%
Output
33.4%
OxyCFB TechnologyPenalty from Oxycombustion
Adapted from Andersson, Univeristy of Chalmers
Fuel input
100%
OxyCFB TechnologiesChallenges
Boiler and burner
development “Design issues”
ASU
“Cost of oxygen
production”
CPU
“Removal of impurities”
Demonstration in 10s of MW and large scale needed to prove design, performance and economics
Design
Construct
Learn
Operate
2000 2005 2010 2015 2020 2025 2030 2035
D C A O
COMMERCIAL
400-1600 MW
to 2070
D C A ODEMOSTRATOR 2
400-800 MWTo 2070
DEMOSTRATOR 1
400-800 MWD C A O To 2035
D C A O
PILOT
1-30 MW
D C A
LAB
0.1-0.5 MW
Year
Adapted from R. S. Haszeldine Science 325, 1647-1652 (2009). Published by AAAS
OxyCFB TechnologiesChallenges
Source: Near Zero CO2 Emissions in Coal Firing with Oxy-fuel Circulating Fluidized-Bed Boiler. Chem. Eng. Technol. 2009, 32, No.3, 355-363
OxyCFB TechnologyDifferences of Combustion in O2/CO2
compared to Air-firing
Emissions of OxyCFB BoilersSO2 and Calcium utilisation (Bituminous)
Adapted from A Hotta,: Oxycombustion Development by Foster Wheeler. Clean coal in the future. March. 2009
Emissions of air- and oxy- firing tests at VTT CFB-pilot (30-100 kW)
Emissions of OxyCFB BoilersNO Emissions (Bituminous)
Emissions of air- and oxy- firing tests at VTT CFB-pilot (30-100 kW)
Adapted from A Hotta,: Oxycombustion Development by Foster Wheeler. Clean coal in the future. March. 2009
Dimensions (m) 21x2.7x2.4
Power (MWth) 30 max
O2 (kg/h) 8775
Flue gas recycle (kg/h) 25532
Flue gas (kg/h) 28800
Coal feed (kg/h) 5469
Limestone feed (kg/h) 720
Steam (t/h) 44.6
P(bar) / T (°C) 30 / 250
CIUDEN OxyCFB Boiler
CIUDEN OxyCFB BoilerFlexiburn Project
OxyCFB300 Project
Source: Foster Wheeler
Concluding remarks
OxyCFB technically feasible and cost competitive when majorreduction of CO2 emissions are required
• The established CFB advantages also exist in oxy
• Fuel Flexibitily
• Low NOx
• In bed SO2 capture
• Adapting an existing CFB boiler for oxy technically feasible(24-30 % O2 input)
• Integration of components: ASU, CPU, Combustion island
• Demonstration at large scale are neccesary for theimplementation of the technology at fully commercial size