department of chemical & process engineering the high pressure interactions of coal with co 2...
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Department of Chemical & Process Engineering Field tests are expensive and a set of laboratory tests to screen coals is needed to: Determine the irreversible storage capacity. Measure how tightly bound CO 2 is to different coals. Determine the physical state of CO 2 in coal. OBJECTIVES Which coals are most effective for sequestration?TRANSCRIPT
Depa
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The high pressure interactions of coal with The high pressure interactions of coal with COCO22
Implications for CO2 disposal and CH4 displacement from coal seams
Mojtaba Mirzaeian
Supervisor: Professor Peter.J.Hall
By :By :
Depa
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gINTRODUCTIONINTRODUCTION
Coal is the most abundant fossil fuel and the world depends heavily on it and will continue to do so for years to come.
There is overwhelming evidence for a gradual build up of atmospheric CO2 levels and strong evidence that this is contributing to global warming.
Unminable deep coal seams are attractive as options for the permanent sequestration of CO2
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Field tests are expensive and a set of laboratory tests to screen coals is needed to:
Determine the irreversible storage capacity. Measure how tightly bound CO2 is to different coals.Determine the physical state of CO2 in coal.
OBJECTIVESOBJECTIVES
Which coals are most effective for sequestration?
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A variety of Experimental techniques have been used :
Differential scanning calorimetry Phase change in high pressure CO2 Irreversible sorption capacity Thermodynamics
Temperature programmed desorption
Binding energy of CO2
Small angle neutron scattering
Physical state/location of CO2 in structure
ExperimentalExperimental
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-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
-2
-1.5
-1
-0.5
0
40 60 80 100 120 140 160 180 200
Temperature (oC)
DSC for Wyodak coal (held in 30 bar CO2 atmospher for 24h)
second scan
first scanthird scan
endo
exoH
eat f
low
(W
/g)
Hea
t flo
w (
W/g
)
DSC results DSC results
Glass transition in coal:Glass transition in coal:
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-2
-1
0
1
2
3
40 60 80 100 120 140 160 180 200
Temperature (oC)
The dependence of glass transition temperature of Wyadak on the pressure of CO
2
30 bar
5 bar
10 bar
20 bar
exo
endo
Hea
t flo
w (
W/g
)
DSC resultsDSC results
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Evidence for plasticisation of Coal by CO2.
DSC resultsDSC results
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-2.5
-2
-1.5
-1
-0.5
0
0.5
1
-50 0 50 100 150 200
Temperature (oC)
DSC for Wyodak in N2 atmosphere
exo
endo
Hea
t flo
w (
W/g
)
____ First scan____ Second scan____ Third scan
-3
-2
-1
0
1
2
3
-50 0 50 100 150 200
Temperature (oC)
DSC for Wyodak in CO2 atmosphere
exo
endo
Hea
t flo
w (
W/g
)
____ First scan____ Second scan____ Third scan
DSC resultsDSC results
Irreversible strong interactions of coal with COIrreversible strong interactions of coal with CO22
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Thermodynamic of coal/COThermodynamic of coal/CO22 interactions interactions
DSC resultsDSC results
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0
1 10-11
2 10-11
3 10-11
4 10-11
5 10-11
300 350 400 450 500 550
Des
orpt
ion
rate
(arb
.un)
Temperature (K)
TPD-MS spectra of CO2 from Pittsburgh#8
Fresh sample
Sample loaded with 24 bar CO2 for 25h.
CO2 desorption from coal is an activated process.
CO2 desorption fromcoal follows a first order kinetic model.
TPD-MS resultsTPD-MS results
0
2 10-11
4 10-11
6 10-11
8 10-11
300 350 400 450 500
Des
orpt
ion
rate
(arb
.un.
)
Temperature (°K)TPD-MS spectrum of CO
2 adsorbed on
Pittsburgh#8 coal at 15 bar for 20 hours
Exp. DataRedhead Equ.
-2 10 -11
0
2 10-11
4 10-11
6 10-11
8 10-11
300 310 320 330 340 350 360
Des
orpt
ion
rate
(arb
.un.
)
Temperature (°K)
Ed= 11202 cal/mole
ß = 20 ° K /min
Kd =105378.86 S-1
Exp. Data
Redhead Equ.
Residual
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Desorption characteristics of Desorption characteristics of COCO22 from Pittsburgh #8 coal from Pittsburgh #8 coal
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0.01
0.1
1
10
100
1000
0.01 0.1 1
35 bar CO2 10 min35 bar CO2 20 min35 bar CO2 30 min35 bar CO2 1 hr35 bar CO2 1.5 hr35 bar CO2 2 hrs
Scat
terin
g cr
oss
sect
ion
(cm
-1)
Scattering wave vector q (Ao -1 )
SANS on Illinois #6 at 35 bar CO2 at various times
0.01
0.1
1
10
100
1000
0.01 0.1 1
0 bar CO225bar CO232bar CO2
Scat
terin
g cr
oss
sect
ion
(cm
-1)
Scattering wave vector q (Ao -1 )
SANS on Illinois #6 at various CO2 pressures for 2h.
Decrease in scattering intensities after loading with CO2 gives evidence that CO2 can access to
entire pores in coal.
No change in scattering intensities with time shows that CO2 can not diffuse through the coal matrix in
the time scale of experiment.
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Coal/CO2 interactions are strong and irreversible.
Conclusions Conclusions
The values of energy of Coal/CO2 interactions decrease with increase in coal rank suggesting low rank coals are better for CO2 sequestration.
CO2 causes significant plasticisation effect in coal and changes coal structure.
CO2 desorption from coal is an activated process and follows a first order kinetic model.
Coals offer an attractive means for the long term sequestration of CO2 .
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Thank-YouThank-You
&&
QuestionsQuestions
[email protected]@strath.ac.uk
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