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3rd Oxyfuel Combustion Conference yPonferrada, SpainTechnical session 3c
Clarification of gasification behavior of gsolid fuel char prepared under CO atmosphereCO2 atmosphere
Tokyo Institute of Techonology
Kiyomi SHIMOMURA*Kiyomi SHIMOMURA , Hirotatsu WATANABE, Ken OKAZAKI
Energy Phenomena Laboratory
Today’s contents 2
Background Research purpose Experiment
– Sample and setup– Experiment condition
Result and Discussion– Pyrolysis experiment
h f– Char gasification experiment
Conclusion
Energy Phenomena Laboratory
Today’s contents 3
Background Research purpose Experiment
– Sample and setup– Experiment condition
Result and Discussion– Pyrolysis experiment
h f– Char gasification experiment
Conclusion
Energy Phenomena Laboratory
Background 4
CO2 ≈ 13%Air combustion
FuelH2OO2N2
N2
2Boiler
Air
FuelFlue gastreatment
O2/CO2 combustion
Flue gas composition
Boiler
ASUAir O2
FuelFlue gastreatment
N2H2OO2N
CO2
CO2 ≈ 95%2 2
ASU 2
Flue gas composition
N22
l li
※ASU : Air Separation Unit
Flue gas recycling(Mainly CO2 ) Easy to treat/handle CO2
(Eg. Carbon capture & Storage)
Energy Phenomena Laboratory
Research purpose 5
Because CO2 is highly concentrated in O2/CO2 combustion→ The pyrolysis process of solid fuel undergoes in CO2 atmosphere.py y p g 2 p
→ The mechanism of production of char in pyrolysis process is considered
to be different, which causes the difference of char property.to be different, which causes the difference of char property.Possible changes:• Reaction between CO2 and alkali metal
(Influence on catalytic effect of alkali metal[1])
• Increase of specific surface area[2](enhancement of gasification reaction)
R hInvestigate the influence of these properties on char gasification → Clarify the effect of CO2 in char
Research purpose
gasification
[2] Renu Kumar Rathnam et. al., Fuel Processing Technology,2009,6,797–802[1] McKee, D. W, Marcel Dekker, New York, 1981, 16, 1‐118
Energy Phenomena Laboratory
6
Background Research purpose Experiment
– Sample and setup– Experiment condition
Result and Discussion– Pyrolysis experiment
h f– Char gasification experiment
Conclusion
Energy Phenomena Laboratory
Sample & Setup 7
Table: proximate analysis &ash contents (ICP‐AES) flowmeter Reaction tube
Alkali lignin [wt%]
Volatile matters 46.4heater
sample
Volatile matters 46.4Fixed carbon 23.1
Water 11.8
CO2
Thermometric pointPt cell
Ash 18.2
Ash Na 55.0 thermobalancePressure meterAr
[mg/g] K 1.03
PC
Air compressor
Alkali lignin was employed to PC
Vacuum pump
Fig. Thermobalance
Alkali lignin was employed to extract the effect of alkali metal in CO2 environment
Energy Phenomena Laboratory
Experiment method (Pyrolysis) 8
Pyrolysis exp.Gas CO2 or ArGas flow rate 0 8 ℓ/minGas flow rate 0.8 ℓ/minHeating rate 1 K/sFinal temp. 700oCSample mass 40mg
The chars were analyzed by FT-IR, N2 BET analysis and SEM images to investigate the influence of CO2on char properties.
Energy Phenomena Laboratory
9Experiment method (Char gasification)
Pyrolysis GasificationGas CO2 or Ar AirSwitching
CO2 or Ar AirGas flow rate 0.8 ℓ/min 0.8 ℓ/minHeating rate 1 K/s -
Final temp 700oC 700oC, 750oC,800oC, 850oC, 900oC, 950oC, Final temp. 700oC , , , , , ,1100oC,1150oC, 1200oC
pyrolysisswithcing
gasification
i
X
Wdt/dWdt/dX
=gasification rate600700800900
25.00
30.00
35.00
[mg]
Temperat
35
30
25
20X:Char conversion ratio W:Weight
gasification rate
200300400500
5 00
10.00
15.00
20.00
Wei
ght
ture [ oC]
20
15
10
5 char
0100
0.00
5.00
0 500 1000Time [sec]
5
0Pyrolysis (700oC) and Gasification (900oC)
Arrhenius plot (X=0.5)
Energy Phenomena Laboratory
10
Background Research purpose Experiment
– Sample and setup– Experiment condition
Result and Discussion– Pyrolysis experiment
h f– Char gasification experiment
Conclusion
Energy Phenomena Laboratory
11Result and Discussion (Pyrolysis)
Reaction between CO2 and alkali metal
FT‐IR1450 cm-1 880 cm-1
lignin‐char‐CO2 = lignin char made in CO2
lignin‐char‐Ar = lignin char made in Ar
u.] Wavelength of 1450cm‐1 and 880cm‐1
are assigned to the peaks for carbonate
Na2CO3
tens
ity [a
.u are assigned to the peaks for carbonate ion[1].
Carbonate was formed in lignin char
500100015002000
Int g
which was prepared in CO2atmosphere. This result matches with our previous research[3].
Wavelength [cm-1]
[3] Watanabe, H. et al., Proceedings of the Combustion Institute, 2013, 34, 2339‐2345
with our previous research .
[1] McKee, D. W, Marcel Dekker, New York, 1981, 16, 1‐118
Energy Phenomena Laboratory
12Result and Discussion (Pyrolysis)
Surface area of char
SEM 10μm
Specific surface area [m2/g]
N2 BET analysis
Specific surface area [m2/g]lignin‐char‐CO2 392lignin‐char‐Ar 0 73
Lignin‐char‐CO2 Lignin‐char‐Ar
lignin char Ar 0.73
Drastic development of pores in lignin-char-CO2 is considered to be2
The char prepared in CO2 atmosphere has more porous surface
lignin char CO2 is considered to be caused by char-CO2 reaction.
The char prepared in CO2 atmosphere has more porous surface and larger surface area than that prepared in Ar atmosphere
Energy Phenomena Laboratory
13
Background Research purpose Experiment
– Sample and setup– Experiment condition
Result and Discussion– Pyrolysis experiment
h f– Char gasification experiment
Conclusion
Energy Phenomena Laboratory
14Result and Discussion (Char gasification)
lignin-char-CO2 = lignin char made in CO2
lignin-char-Ar = lignin char made in ArGasification rate of lignin char
lignin char Ar lignin char made in Ar
5 5Zone II Zone I Zone I = Kinetic controlled
i-5.5
.5 [s
-1]
↑
regionZone II = Internal diffusion
controlled region
-6.5
ndX
/dt x
=0
▲lignin‐char‐CO2
↑950oC
↑1200oC
700oC↓ i
X
Wdt/dWdt/dX
-7.5 6 7 8 9 10 11
ln ▲lignin char CO2×lignin‐char‐Ar
X:char conversion ratio W:Weight
=gasification rate
6 7 8 9 10 11104/T [K-1]
Fig. Arrhenius plot of ligninchar gasification in air environment
ratio W:Weight
Energy Phenomena Laboratory
15Result and Discussion (Char gasification)
lignin-char-CO2 = lignin char made in CO2
lignin-char-Ar = lignin char made in ArGasification rate of lignin char
lignin char Ar lignin char made in Ar
5 5Zone II Zone I Zone I = Kinetic controlled
i-5.5
.5 [s
-1]
↑
regionZone II = Internal diffusion
controlled region
-6.5
ndX
/dt x
=0
▲lignin‐char‐CO2
↑950oC
↑1200oC
700oC↓ i
X
Wdt/dWdt/dX
-7.5 6 7 8 9 10 11
ln ▲lignin char CO2×lignin‐char‐Ar
X:char conversion ratio W:Weight
=gasification rate
6 7 8 9 10 11104/T [K-1]
Fig. Arrhenius plot of ligninchar gasification in air environment
ratio W:Weight
Energy Phenomena Laboratory
Result and Discussion (Char gasification) 16
Zone I (Kinetic controlled region):
A h l
600
800
40
50
] o C]
Pyrolysis GasificationAt the temperature lower than 750oC, lignin char prepared in CO2 (lignin‐char CO ) didn’t gasify
400
600
20
30
eigh
t [m
g]
pera
ture
[lignin-char -CO2char‐CO2) didn t gasify, while the lignin char prepared in Ar (lignin‐char‐Ar) gasified.
Carbonate formation in ligin char prepared in
20010
20
We
Tem
p
lignin-char-Ar
Ar) gasified.
ligin char prepared in CO2 inhibited char gasification at lower
( 750oC)
00750 1250 1750 2250
Time [s]temperature (<750oC).Gasification reaction at 700oC
Energy Phenomena Laboratory
Result and Discussion (Char gasification) 17
Zone I (Kinetic controlled region):How the carbonate inhibit gasification reaction?g• P. J. van Eyk et al.[4] reported that Na works as a catalyst by repeating the following redox reaction.
(‐CNa)+1/2O2 → (‐CONa) ・・・・oxidation(‐CONa)+C → (‐CNa) +CO ・・・・reduction
• (‐CNa) plays important role in char gasification reaction.
• In pyrolysis in CO2 environment, it can be assumed that Na py y 2 ,reacts with CO2 to form Na2CO3 so that Na cannot act as the specie which can contribute to the catalytic reaction shown above especially at lower temperatureabove, especially at lower temperature.
[4] van Eyk, P. J. et al., Combustion and Flame, 2011, 158, 2512‐2523
Energy Phenomena Laboratory
18Result and Discussion (Char gasification)
lignin-char-CO2 = lignin char made in CO2
lignin-char-Ar = lignin char made in ArGasification rate of lignin char
lignin char Ar lignin char made in Ar
5 5Zone II Zone I Zone I = Kinetic controlled
i-5.5
.5 [s
-1]
↑
regionZone II = Internal diffusion
controlled region
-6.5
ndX
/dt x
=0
▲lignin‐char‐CO2
↑950oC
↑1200oC
700oC↓ i
X
Wdt/dWdt/dX
-7.5 6 7 8 9 10 11
ln ▲lignin char CO2×lignin‐char‐Ar
X:char conversion ratio W:Weight
=gasification rate
6 7 8 9 10 11104/T [K-1]
Fig. Arrhenius plot of ligninchar gasification in air environment
ratio W:Weight
Energy Phenomena Laboratory
19Result and Discussion (Char gasification)
Zone II (Internal diffusion controlled region):Lignin char made in CO had higher gasification rate than that of char‐ Lignin char made in CO2 had higher gasification rate than that of char
made in Ar.SEM 10μm
During pyrolysis in CO2, both micro and macro pores of char developed more drastically
ligninchar CO ligninchar Ar
developed more drastically. → It makes gasification agents to diffuse more easily.
ligninchar‐CO2 ligninchar‐Ar
More porous morphology and larger specific surface area of char made in CO2 enhanced gas transport leading to increase of gasification rate.
Energy Phenomena Laboratory
20
Background Research purpose Experiment
– Sample and setup– Experiment condition
Result and Discussion– Pyrolysis experiment
h f– Char gasification experiment
Conclusion
Energy Phenomena Laboratory
21Conclusion
Properties of lignin char in CO2:– The lignin char prepared in CO2 environment contained carbonateThe lignin char prepared in CO2 environment contained carbonate and it had more porous surface and larger specific surface area.
Char gasification behavior of lignin char:– Zone I (Kinetic controlled region):
Carbonate formation inhibited char gasification, by changing Na form in charform in char.
– Zone II (Internal diffusion controlled region): More porous morphology and larger specific surface area of char p p gy g pdue to char‐CO2 gasification enhanced gas transport leading to increase of gasification rate.
CO2 in pyrolysis of lignin plays different roles in char gasification process, according to the rate limiting factors.
Energy Phenomena Laboratory
Thank you for your kind attention
Energy Phenomena Laboratory
Characteristics of lignin
Energy Phenomena Laboratory
Lignin (proximate & ultimate analysis) 24/14
lignin [wt%]
Ultimate analysislignin [wt%]
Proximate analysis
g [ ]C 46.5H 4.49
g [ ]Volatile matters 46.4Fixed carbon 23.1
W 11 8N 0.08S 2.51
Water 11.8Ash 18.2
O 28.19Ash 18.2
Ash composition of lignin [mg/g] (ICP-AES)Lignin Ion-exchanged ligninLignin Ion exchanged lignin
N a 55.0 10.5K 1.03 0.25
Energy Phenomena Laboratory
P l i i tPyrolysis experiment
Energy Phenomena Laboratory
26Result (Pyrolysis)
FTIR analysis1440 cm-1 880 1
Pyrolysis of lignin (biomass)
Weight 10%UP
1440 cm 1 880 cm-1
.u.]
tens
ity [a
.In
t
300 430 600 800T t [oC] 500100015002000
Wavelength [cm-1]
Li i h d i COligninchar-CO2 = lignin char made in CO2
Temperature [oC]
Lignin‐char prepared in CO2contains carbonateNa2CO3
ligninchar-Ar = lignin char made in Ar
Energy Phenomena Laboratory
実験結果:ligninチャー 27C123 東工大 下村聖実
FTIRl CO l AN COli i CO li i A
1440 cm-1 880 cm-1coal-CO2 coal-ArNa2CO3lignin-CO2 lignin-Ar
1440 cm-1 880 cm-1
ity [a
.u.]
sity
[a.u
.]
Inte
nsi
Inte
ns
500100015002000Wavelength [cm-1]
500100015002000Wavelength [cm-1]
[3] Watanabe, H. et al., Proceedings of the Combustion Institute 2012
lignin Coal
Energy Phenomena Laboratory
G ifi ti i tGasification experiment
Energy Phenomena LaboratoryExperiment method(Gasification) 29(Gasification)
Pyrolysis
Keep @ 700oCfor 3min.
GasificationPyrolysisCO2 or Ar
@ 1K/s to 700oC Switching gas
GasificationAir
700oC – 1200oC
Experiment condition
Switching gasCO2 or Ar→ Air
Pyrolysis GasificationGas CO2 or Ar AirSwitching
Experiment condition
Gas flow rate 0.8 ℓ/min 0.8 ℓ/minHeating rate 1 K/s -
700oC 750oC 800oC 850oC 900oCFinal temp. 700oC 700 C, 750 C,800 C, 850 C, 900 C, 950oC, 1100oC,1150oC, 1200oC
Sample mass 40mg -
Energy Phenomena Laboratory
Result: Gasification profile 30
lignin 700oC(CO2) → 900oC(Air)
dWWdt/dW .X.X
X1010
pyrolysis
swithcinggasification
i
X
Wdt/dWdt/dX
dtX
700800900
30.00
35.00
g]
Temp
35
30
25 i
X:char conversion ratio W:Weight
=gasification rate400500600
15.00
20.00
25.00
eigh
t [m
g erature [ o
Wi
25
20
15
At each temperature,
ratio W:Weight
100200300
5.00
10.00 We oC
]10
5
0 gasification rate at X=0.5 was compared.
00.00 0 500 1000
Time [sec]
0
Energy Phenomena Laboratory
Ad d di iAdvanced discussion
Energy Phenomena Laboratory
Why carbonate inhibit gasification 32/14
The key reaction for Na to work as a catalyst in char gasification[4](‐CNa)+1/2O2 → (‐CONa) ・・・・oxidation( CNa) 1/2O2 → ( CONa) oxidation(‐CONa)+C → (‐CNa) +CO ・・・・reduction
When Na CO was formed in the pyrolysis process in CO
Pyrolysis Gasification
When Na2CO3 was formed in the pyrolysis process in CO2atmosphere, the Na loose chance to act as a catalyst
Ar ‐CNa(‐CNa) + 1/2O2 → (‐CONa) (‐CONa) + C → (‐CNa) + CO
y y
CO N CO
‐COONa
CO2 ‐Na2CO3
[4] van Eyk, P. J. et al., Combustion and Flame, 2011, 158, 2512‐2523
Energy Phenomena Laboratory
Discussion 33
Zone IIt has already revealed that carbonate (mainly Na2CO3) is formed in the lignin char
Lignincha
It has already revealed that carbonate (mainly Na2CO3) is formed in the lignin char made in CO2 (Ligninchar-CO2).
Lignin gr
Na2CO3,…
gR-COONa
NaCl, NaOH, …CO2
, ,
Different formations of Na seems to have different effects on gasification at gtemperature lower than 750oC.→ Analyze the formation of Na
GOAL:To clarify the order of activeness as catalyst of gasification at lower temperature(-750oC) with respect to the formation of Na.
s8
Slide 33
s8 これを、図式化したほうがよかった。触媒の活性度を、グラフみたいにして、NaCl > Na2CO2 > NaOHとかみたいに。shimomura, 18/06/2013
Energy Phenomena Laboratory
B k dBackground
Energy Phenomena Laboratory
CO2 separatation cost and energy 35/13
cost$55/tonne of CO2
$35/tonne of CO2
O2/CO2 Air
O2/CO2 Air (by chemical absorption)
O2/CO2 AirASU Power [MWe] 86 -CO2 Separation Unit Power [MWe] 53 40H t d t [MW ] 340
energy
D. Singh et al. / Energy Conversion and Management 44 (2003) 3073-3091
Heat duty [MWth] - 340Cooling duty [MWth] 142 430
Energy Phenomena Laboratory
Background:CCS 36
CCS: Carbon Capture and Storage
C t
Capture Storage Transport Compress
Storage
Compress
Capture
TransportStorage
PowerPower Plant
CompressCO2 CO2
Energy Phenomena Laboratory
Objective 37
O f l C b ti
How the enriched CO2 affects oxyfuel combustion?
(C li t d t l )Oxyfuel Combustion
Pyrolysis
(Complicated to analyze)
Pyrolysis Emission of volatiles and formation of char Very important step, which also affects the following steps in combustion The effect of CO in pyrolysis process of oxyfuel combustion is still unknown
Gasification
The effect of CO2 in pyrolysis process of oxyfuel combustion is still unknown
The char formed in pyrolysis process is gasified Gasification behavior of char strongly dependent on char property
Objective:Objective: To clarify the effect of CO2 in pyrolysis process by investigating char property and char gasification behavior
Energy Phenomena Laboratory
Background 38
Pyrolysis:1000~1700
JCOAL:http://www.jcoal.or.jp/cshandbook/dlfiles/c3‐4.pdf
Combustion phenomenon of coal particle
Pyrolysis:‐Emission of volatile mattersF ti f h
flame
volatiles Air
End of emission of volatiles
‐ Formation of char
Ignition
ture
volatilesCombustion of char
e tempe
rat
fly ash
Gasification:
Particle
Rapid increase of particle temperature
Gasification:Gasification of char by gasifying agents (O2 ,CO2)
Air+coal
pulverized coal
Distance from burner
Energy Phenomena Laboratory
Background 39
Pyrolysis:1000~1700
Combustion phenomenon of coal particle O2/CO2 combustionPyrolysis:
‐Emission of volatile mattersF ti f h
flame
volatiles Air
End of emission of volatiles
‐ Formation of char
Ignition
ture
volatilesCombustion of char
CO2
e tempe
rat
fly ash
Gasification:
CO2
2
CO2
Particle
Rapid increase of particle temperature
Gasification:Gasification of char by gasifying agents (O2 ,CO2)
Air+coal
2
pulverized coal
Distance from burner
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