Tokyo Institute of TechnologySchool of Engineering
Ken OKAZAKIProfessor, Dept. of Mechanical and Control Engineering
Graduate School of Science and EngineeringTokyo Institute of Technology (Tokyo Tech), Japan
The 4th Oxy-fuel Capacity Building CourseTokyo Institute of Technology, Japan
September 2-3, 2012
The Relevance of Oxy-fuel Technologyfor Japan
Inter-Departmental Organizationfor Environment and Energy
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Tokyo Institute of TechnologySchool of Engineering
Outline1. Key issues to mitigate the global
warming
2. Clean and high efficiency coal technology in Japan
3. Important role of CCS
4. Oxy-fuel combustion (pulverized coal)• Origin, history (past – present - future)• Basic studies (lab. scale, pilot scale)• Callide Project (Australia-Japan)• Future prospect (demonstration, commercial)
5. Concluding remarks 2
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• Global warming is due to an extraordinary large amount of CO2 emissions.
• Net and quantitative contribution to CO2 reduction is the most important (large scale).
• Contribution of renewable energies is important but very small at present.
• Technologies to suppress CO2 emissions still depending on fossil fuels are urgent issues (ex. coal-fired power stations with CCS, integration of fossil fuels with hydrogen energy system).
• Only energy-saving or high efficiency is definitely not enough.
• Harmony among public society, technology innovations and economical growth.
• Fair and effective collaboration among all major countries including both developed countries and developing countries.
Key Issues of Countermeasures for Global Warming
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(Far future)
CO2 + H2Fossil Fuel(Coal, Oil ..)
O2/CO2
Combustion
CO2 Recovery
Air-blownCombustion
CO2 Separationand Recovery(MEA, KS-1 ..)
CO + H2
gasificationshift reaction
Hydrogen Energy Systemwith Exergy Regeneretion
(Fuel Cell …)
Renewable Energy(Wind, PV ..)
Electricity
H2 + O2 H2O
CO2 Sequestration(Ocean, Geological ..)
CO2 + H2
(Future)
FutureGen
steam reforming
exergy enhancementof low quality waste heat
CO2 + H2CO2 + H2Fossil Fuel(Coal, Oil ..)
O2/CO2
Combustion
CO2 Recovery
Air-blownCombustion
CO2 Separationand Recovery(MEA, KS-1 ..)
CO + H2
gasificationshift reaction
Hydrogen Energy Systemwith Exergy Regeneretion
(Fuel Cell …)
Renewable Energy(Wind, PV ..)
Electricity
H2 + O2 H2O
CO2 Sequestration(Ocean, Geological ..)CO2 Sequestration(Ocean, Geological ..)
CO2 + H2
(Future)
FutureGen
steam reforming
exergy enhancementof low quality waste heat
Integration of Fossil Fuel, Hydrogen and CO2 Sequestration
Roadmap toward Sustainable Economy
Oxy-firing
Feb. 27, 2003
<Okazaki, J. Energy, 2004>(Short term)
(Medium term)
CO2 + H2Fossil Fuel(Coal, Oil ..)
O2/CO2
Combustion
CO2 Recovery
Air-blownCombustion
CO2 Separationand Recovery(MEA, KS-1 ..)
CO + H2
gasificationshift reaction
Hydrogen Energy Systemwith Exergy Regeneretion
(Fuel Cell …)
Renewable Energy(Wind, PV ..)
Electricity
H2 + O2 H2O
CO2 Sequestration(Ocean, Geological ..)
CO2 + H2
(Future)
FutureGen
steam reforming
exergy enhancementof low quality waste heat
CO2 + H2CO2 + H2Fossil Fuel(Coal, Oil ..)
O2/CO2
Combustion
CO2 Recovery
Air-blownCombustion
CO2 Separationand Recovery(MEA, KS-1 ..)
CO + H2
gasificationshift reaction
Hydrogen Energy Systemwith Exergy Regeneretion
(Fuel Cell …)
Renewable Energy(Wind, PV ..)
Electricity
H2 + O2 H2O
CO2 Sequestration(Ocean, Geological ..)CO2 Sequestration(Ocean, Geological ..)
CO2 + H2
(Future)
FutureGen
steam reforming
exergy enhancementof low quality waste heat
Nuclear Energy
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Coal Flow around the World (Outlook 2009)
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Coal is Japan’s Lowest Cost Option in Post-Nuclear Age
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(Net efficiency : 42%)
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Present Status of Clean Coal Technology in Japan
NOxand SOxemissions from fossil fuel fired power stations
Acid Raintechnology transferfrom Japan
CO2 Problemsonly increase of eff.is not enough, andnew strategies are definitely necessary.
In Japan1 GW P.C. Stations
Net eff. > 40 %NOx< 100 ppm
U.S.A. Can. U.K. Fra. Ger. Ita. Jap.
NOx: 0.017, SOx: 0.070 (Isogo No.1)
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Startup year
No.1 Isogo Power Station
(Press.)
(16.6)
(24.1)
450
483485
538
566 593
(31.0)
Temp.
5
10
15
20
25
600
550
500
450
400
Ste
am p
ress
ure
( M
Pa
)
(4.1)
‘55 ‘60 ‘65 ‘70 ‘90 ‘95 2000
30
~~
~
610
~~
~
Ste
am te
mpe
ratu
re(℃)
620
Change of Steam Conditions of Coal-Fired Power Plant in Japan
(USC)
Nikkei Newspaper, Sept.8, 2008Steam temp. : → 700 ℃Net efficiency42% → 46% (2015) → 48% (2020)
Hitachi, Toshiba, MHI
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Efficiency of Coal-fired Power Generation in Various Countries(LHV, %)
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CO2 recovery from coal-fired power station
2.Post-combustion system (From flue gas)
3.Oxy-fuel combustion system
ASU
Coal(C,H,O,N,S,Ash) Boiler
Flue gas recycle (CO2,・・・ )H2O,SO2
O2
Air(N2、O2)
N2,O2N2
Flue gas treatment
ASU
O2
Air(N2、O2)
N2
Gasifier Syngas treatmen
tCO shift
CO2 storage/sequestration
Compress/Cooling
CO2 separation
GTHRSG
Coal(C,H,O,N,S,Ash)1.Pre-combustion system (Gasifier)
Boiler
CO2
Coal(C,H,O,N,S,Ash)Air(N2、O2)
N2,H2O,O2
Flue gas treatment
CO, H2 CO2, H2
H2
CO2 storage/sequestration
CO2 storage/sequestration
Compress/Cooling
Compress/Cooling
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Panel: Oxy-Fuel Technology
Oxy-Fuel Technology I : Overview & Demonstrations
Oxy-Fuel Technology II : Emissions
Oxy-Fuel Technology III: Experimental Studies
Oxy-Fuel Technology IV: Understanding Oxy-Combustion Impacts
Oxy-Fuel Technology V : Burner Developments
Presentations
2004 No presentation
2005 One presentation
2006 One session
2007 Full sessions (full of audience)
… …
2011 Full sessions (full of audience)
Oxy-Coal Combustion
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July 13, 2012
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Part IIntroduction to oxy-fuel combustion
Part IIOxy-fuel combustion fundamentals
Part IIIAdvanced oxy-fuel combustion concepts and developments
Contents
“Oxy-fuel combustion for power generation and carbon dioxide (CO2) capture”
Editted by Ligang Zheng
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Oxyfuel system development history in Japan
Oxyfuel basic study was performed from 1990 Demonstration Ready by the end of 1990’s Demonstration Project was conducted from 2004, and operation started
in March, 2012
201520102005200019951990
The first national Oxyfuel R&D project in Japan
Japan and Australia Joint Demonstration Project
Now
2020
Demonstration ReadyBasic Study(NEDO)
Feasibility Study(NEDO)
Callide Project(METI/NEDO)
Application Study
Demonstration
Future Study
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O2/CO2 (Oxy-firing) Coal CombustionConventional pulverized coal combustion
CO2 concentration in flue gas is about 13 %
Great energy consumption to separate CO2
O2/CO2 pulverized coal combustion
CO2 concentration in flue gas is enriched up
to 95 %
Easy and efficient CO2 recovery
Small amount of exhausted gas (extremely low amount of NOx, SOx)
O2
Coal
Recycled gas
O2 productionAir
Furnace
Practically realized by IshikawajimaharimaCo., Ltd. ASU
<Okazaki, Ando, ENERGY, 1997>
Oxy-firing of coal
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CoalBoiler
GRF
AH
Stack
CO2 tank
CO2 liquefaction
Non-condensable gas
Flue gas treatment & compressor Cold Box
(CO2, H2O, SO2…)
FFFGLPH
<Oxyfuel boiler>
Mill
O2Air
N2
ASU
< CO2 capture process >
<Oxygen production & supply>
Study Items for Commercialization
Oxyfuel Boiler (Furnace) Combustion characteristics Flame stability Radiation heat transfer
Oxygen production & supply Method & System Oxygen purity
Oxyfuel Plant (Integrated operation) Performance (Boiler Efficiency, CO2 capture rate) Control (Oxyfuel, MFT) Operation
(Mode change, Load range, Start-up, Shut-down) Durability and Safety
CO2 Capture Process System Optimization Impurities Removal Outlet CO2
Properties
Oxyfuel Boiler (Flue Gas) Corrosion Environment Trace Element 21
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Time
Sca
le
Pilot Plant (Horizontal)
Commercial
Large Scale Demonstration
Oxyfuel system development history in Japan
1990 1993 2011 2015~1998
Pilot Plant (Vertical)
Drop Tube FurnaceIgnition apparatus under Micro-gravity
Callide-A
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Pilot Plant(Horizontal)
Pilot Plant(vertical)
Demo Plant(Callide)
Capacity Max. 150kg/h(Coal)(1.2MW thermal)
30MWe(100MWth)
Furnace I.D. 1.3m x L 7.5m Actual Furnace
Year 1993 1998 2011
Photo
Pilot plant and demo plant
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Coal jet ignitionChemistryBurner aerodynamics and heat transfer
Char burnoutSOx
Ash partitioningDeposition Trace elements
Combustion by-productsNOx, SOx
Heat transferRadiant zoneConvective zone
Basic Study Items
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The first oxyfuel combustion trial in 1993
Air (Wind-box O2: 21%)
Oxyfuel (Wind-box O2: 21%)
Oxyfuel (Wind-box O2: 30%)
Initial Combustion Test
Difficult of holding the stable flame in case of wind-box O2 of 21% in oxyfuel
25
Need to increase the inlet-O2 in order to keep the stable flame and radiation heat transfer
Distance from burner exit [m]
Fla
me
Tem
p. [d
egC
]
Distance from burner exit [m]
Fla
me
Tem
p. [d
egC
]
Distance from burner exit [m]
Fla
me
Tem
p. [d
egC
]
< NEDO Report, 1993 > 25
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Flame Propagation Velocity in High CO2 Concentration
In CO2/O2, flame brightness reduces and flame becomes unstable. Flame propagation velocity in CO2/O2 largely decrease to 1/3–1/5 of that in N2/O2
Flame Behavior
0 1 2 3 4
Coal A(N2/O2)
Coal B(N2/O2)
Coal C(N2/O2)
Coal A(CO2/O2)
Coal C(CO2/O2)
Coal concentration [kg/m3]
Coal C CO2/O
2
Coal C N2/O
2
Coal A N2/O
2
Coal A CO2/O
2
0
0.5
1.0
1.5
Result of gravity-free experiment
30mm
Ignition
5ms
10ms
15ms
20ms
Coal A, N2/O2
Bright Low light
Coal C, N2/O2 Coal C, CO2/O2
< Suda & Okazaki, FUEL, 2007 >
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One-Dimensional Flame Propagation Model
Δl x
Ignition source
Tw Radiation
Absorption by gas or particle
Scattering by particle
Tp(n) Tg(n)
Heat conduction betweengas and particle
x=L=N×Δl
n=N Flame position Tp(n)>Tig
Volatile releaseand combustion
Element n=1
One-Dimensional Model0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
N2/O2CO2/O2CO2/O2,k=0
Coal concentration [kg/m3]
Calculated Results of Flame Propagation Velocity
Large decrease of flame propagation velocity is mainly due to large heat capacity and small thermal diffusivity in CO2/O2
< Suda & Okazaki, FUEL, 2007 >
In N2/O2
In CO2/O2
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CaCO3
Easy and efficient CO2
separation · recovery
Small amount ofexhausted flue gas(Extremely low NOx,SOx)
Recycled gas (Mainly CO2 including NOx, SOx)
CoalO2
High concen-tration CO2
Furnace
Recycled heat
Easy and efficient CO2
separation · recovery
Intensify coal combustionDecrease NO further through combustion with low O2 concentrationImprove fuel flexibilityBroaden load change range of a boiler
Additional merits
Schematic of O2/CO2 Coal Combustion with both mass and heat recirculation
SOx emissions)
CaCO3
Easy and efficient CO2
separation · recovery
Small amount ofexhausted flue gas(Extremely low NOx,SOx)
Recycled gas (Mainly CO2 including NOx, SOx)
CoalO2
High concen-tration CO2
Furnace
Recycled heat
Easy and efficient CO2
separation · recovery
Intensify coal combustionDecrease NO further through combustion with low O2 concentrationImprove fuel flexibilityBroaden load change range of a boiler
Additional meritsIntensify coal combustionDecrease NO further through combustion with low O2 concentrationImprove fuel flexibilityBroaden load change range of a boiler
Additional merits
Schematic of O2/CO2 Coal Combustion with both mass and heat recirculationSchematic of O2/CO2 Coal Combustion with both mass and heat recirculation
SOx emissions)
<Liu & Okazaki, FUEL, 2003>
Further NOx Reduction by Heat Recirculation
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Base case
Oxy-fuelO2 : 30%H.R.: 0%
Oxy-fuelO2 : 21%H.R.: 0%
Oxy-fuelO2 : 15%H.R.: 40%
ConventionalO2 : 21%H.R.: 0%
<Liu & Okazaki, FUEL, 2003>
Drastic Reduction of CR* (Fuel-N to NOx) by Oxy-firing
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Air
Air Oxy1 Oxy2 Oxy3
Total gas flow 142t/h 117t/h 140t/h 170t/h
Total O2 conc. 21% 30.2% 26.5% 21.7%
FEGT Base Lower Nearly equal Higher
Heat absorption Base Lower Nearly equal Higher
Oxy 1 Oxy 2 Oxy 3
30
40
50
60
70
20 25 30 35Fur
nace
hea
t abs
orp
tion
(MW
)
O2 content of total gas (wetvol%)
Air caseOxy case
WB O2: 30wet%
WB O2: 40wet%
WB O2: 50wet%
Left Front Right Rear Left Front Right Rear Left Front Right Rear Left Front Right Rear
Simulation results suggests that about 27% of total O2 concentration seems to be the same heat absorption in furnace as air combustion
Need to be the same furnace heat absorption in case of retrofit from air combustion boiler
Simulation of heat absorption
< NEDO Report, 2005 >
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Flame temperatureHeat flux
Same level with heat flux at air in case of 27% total O2 Concentration Flame temperature was 50 degree C lower than that of air
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
0 1 2 3 4 5 6
Fla
me
tem
p. (
deg
ree
C.)
Distance from burner throat (m)
Coal B/Oxy
Coal B/Air
Total O2 Conc. : 27%(wet)
0
50
100
0:00 0:10 0:20 0:30 0:40 0:50 1:00
Hea
t Flu
x
Time
Oxy
Air
Heat flux and Flame temperature (Pilot plant)
< CCSD Report, 2006 >
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Combustion Characteristics (IHI pilot plant)NOx behavior
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T. Fujimori (IHI), 34th Int. Symp. On Combustion, Warsaw, August, 2012 33
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Combustion Characteristics (IHI pilot plant)Carbon in ash
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0
5
10
15
20
0 5 10 15 20
SO
3, O
xy m
ode
(ppm
)
SO3 , Air mode(ppm)
Coal A
Coal B
Coal C
0
500
1000
1500
2000
0 500 1000 1500 2000
SO
2, O
xy m
ode
(ppm
)
SO2 , Air mode(ppm)
Coal A
Coal B
Coal C
SO2 SO3
SOx concentration is higher than in air combustion due to recycle
*Negative Pressure in Furnace < CCSD Report, 2006 >
Combustion Characteristics (IHI pilot plant)SOx behavior (1)
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Combustion Characteristics (IHI pilot plant)SOx behavior (2)
: 3 times of the air
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‐Oxyfuel Hg‐
0
0.5
1
AH inlet(450degC)
AH outlet(200degC)
BF inlet(170degC)
BF outlet(120degC)
Hg
(-)
Gas sampling point (Gas Temp.)
Hg2+
Hg0
Dust
0
0.5
1
AH inlet(450degC)
AH outlet(200degC)
BF inlet(170degC)
BF outlet(120degC)
Hg
(-)
Gas sampling point (Gas Temp.)
Hg2+
Hg0
Dust
Gas(Air) Gas(Oxy)
Hg behavior in Oxyfuel was almost the same as Air combustion
Behavior of Trace Elements (Mercury)
< Gotou et al., ICOPE-11 , 2011> 37
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Large difference in char formation
(in N2) (in CO2)
T. Fujimori (IHI), 34th Int. Symp. On Combustion, Warsaw, August, 2012 38
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Operation load
100% 100% 80%
Nozzle type Type1(Initial)
Type2(Optimum)
Type2(Optimum)
O2 conc. on the duct wall[%](Max.)
O2 conc. at the wind-box inlet [%](Max.-Min.)
*Type of injection nozzle is optimized.
(98%) (34%) (34%)
O2 conc. & temp. on the duct wall O2 distribution at the inlet of burner wind-box (Optimization of O2 nozzle)
(3.3%) (1.3%) (0.7%)
*
*
O2 mixing with Recycled flue gas
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Callide Oxyfuel Project
T. Fujimori (IHI), 34th Int. Symp. On Combustion, Warsaw, August, 2012 40
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Callide Oxyfuel Project - Schedule
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Callide Oxyfuel Project – Engineering
T. Fujimori (IHI), 34th Int. Symp. On Combustion, Warsaw, August, 2012 42
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Callide Oxyfuel Project - Retrofit
T. Fujimori (IHI), 34th Int. Symp. On Combustion, Warsaw, August, 2012 43
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Callide Oxyfuel Project – ASU & CPU Layout
T. Fujimori (IHI), 34th Int. Symp. On Combustion, Warsaw, August, 2012 44
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BTG (Blue)
CO2 capture unit(Green)
ASU (Pink) Improvement the power consumption
for ASU & CO2 capture unit Compactification or downsizing of
ASU & CO2 capture unit
Items Cost [billion JPY]
AuxiliaryPower [MW]
Additional Area [m2]
Boiler retrofit 110 30 -
ASU 295 115 21,000
CO2 capture 205 140 17,000
ASU 2 x 500,000 m3N/h
BTG 600/620 degC USC
CPU 770 t/h
Efficiency Base [air case]
Oxyfuelretrofit case
Gross efficiency [%] 44.2 46.0
Net efficiency [%] 42.0 33.4
Feasiblity Study
< NEDO Report, 2011 >
1000MWe retrofit study in Japan
Study Result
Plant Specification
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Thermal Efficiency of 1000 Mwe power Plant
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Future Study
ASU (Air Separation Unit)
BTG (Boiler, Turbine, Generator)
CPU (CO2 Compression and Purification Unit)
Upgrading basic model for simulation
System integration
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Heat transfer sub-modelRadiant zoneConvective zone
Ccal jet ignition sub-modelChemistryBurner aerodynamics and heat transfer
Char burnout sub-modelSOx
Ash partitioning sub-modelDeposition Trace elements
Combustion by-productsNOx, SOx, Hg
Integrated furnace model
Needed Sub-Models for Oxy-PC Furnace
< J.O.L. Wendt, 2007 AIChE Meeting >48
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The oxyfuel R&D and feasibility study were performed from the beginning of 1990’s for national program in Japan, and fundamental data was obtained.Oxyfuel demonstration project is in progress
and operation started in March, 2012.Future activities are in study, and we
progress toward commercialization and future oxyfuel combustion system
Concluding Remarks
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[Acknowledgements]These studies for the demonstration project were supported by METI, NEDO, JCOAL, J-Power and IHI.
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