Post on 18-Mar-2022
SINTEF Energy Research 1
FLUE GAS PROCESSING: Strategies for water management. Water
removal and moisture control via dew point modelling
3rd Oxyfuel Combustion Conference 9-13 September, 2013
Ponferrada, Spain
Jens HETLAND
e-mail: Jens.Hetland@SINTEF.no Web: www.SINTEF.no
SINTEF Energy Research
Trondheim, Norway
SINTEF Energy Research
Water balance: in flue gas processing, water dew point modelling can be used to provide strategies for water management and moisture control, and to suggest whether and where water should be removed from – or added to – systems including CO2 capture and storage (CCS)
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Balanced (complete) combustion reaction:
Generic fossil fuels and their primary conversion
0
0,5
1
1,5
2
2,5
3
3,5
4
0 0,2 0,4 0,6 0,8 1
H/C
O/C
3
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0
0,5
1
1,5
2
2,5
3
3,5
4
0 0,2 0,4 0,6 0,8 1
H/C
O/C
AB
C
DFuel A:Lignite [HHV,LHV]=[12.4,10.5] MJ/kg [H/C,O/C,S/C,N/C] = [0.993,0.263,0.013,0.0286] with 49% water, 6% ash Fuel B:Bituminous coal (Douglas Premium) [LHV]=[27,174] MJ/kg (given) [H/C,O/C,S/C,N/C] = [0.677,0.612,0.003,0.020] with 2% water, 6% ash Fuel C:Anthracite [HHV,LHV]=[30.8,30.3] MJ/kg [H/C,O/C,S/C,N/C] = [0.304,0.030,0.001,0.006] with 2.5% water, 8.9% ash Fuel D:Natural gas [HHV,LHV]=[51.4,45.6] MJ/kg [H/C,O/C,S/C,N/C] = [3.798,0.000,0.000,0.017] with 0% water, 0% ash
20 30 40 50 60Net efficiency (LHV) [%]
0
400
800
1200
1600
2000
Em
issi
on
ind
ex [
kg C
O2
per
MW
h]
Douglas Premium (90% CR)
Lignite (0% CR)
Natural gas (0% CR)
Anthracite (0% CR)
743 State of the art conventional coalDenmark
1124 (World average, conventional coal)
942 (German average)936 (Chinese average, end of 2013)
343 State of the art NGCC(60% efficiency)
Typical emission indices associated with various fuels resulting from this approach
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A dew point model based on the composition of flue gas, from which the vapour pressure is determined
𝑀𝑀𝑔𝑔= 𝑀𝑀CO 2 + y∗MO 2 + c∗MSO 2 +(0.5∗d + ν∗A)∗MN 2 + ν∗B∗MAr
1 + y + c + (0.5∗d + ν∗A ) + ν∗B
𝑝𝑝𝑣𝑣 = (𝑎𝑎2 + 𝑒𝑒 + ν × D) × 𝑝𝑝∑𝑚𝑚𝑚𝑚𝑚𝑚𝑔𝑔𝑎𝑎𝑔𝑔𝑒𝑒𝑚𝑚𝑔𝑔𝑔𝑔 𝑝𝑝𝑝𝑝𝑚𝑚𝑝𝑝𝑔𝑔𝑝𝑝𝑝𝑝𝑔𝑔
𝑝𝑝𝑣𝑣" (𝑝𝑝) = 𝑝𝑝𝑣𝑣
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Dew point resulting from various coal properties applied to oxy-combustion and air-combustion
Water dew point / sulphur acid dew point* of flue gas [C]
Fuel Oxygen-based
combustion (95% O2) Air-based combustion
Lignite 85.67 / 179.36 61.14 / 168.14 Bituminous coal 67.37 / 171.52 38.23 / 149.56 Anthracite 52.23 / 161.94 25.19 / 137.76 Natural gas 87.27 / NA 56.40 / NA
Base power plant: 1 GWe, 45% efficiency (LHV) and 3% excess oxygen
* A.G. Okkes Method: cf. the Engineering Software ES_FlueGas User Manual http://www.engsoft.co.kr/download_e/es_fluegas_e.htm
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Partial pressure of dry gas and water vapour pressure
0 1 2 3 4 5 6 7 8 9
s
0
100
200
300
400
t
~ Ideell gass
Kondenserbaregasser (damp)
0 1 2 3 4 5 6 7 8 9
s
0
100
200
300
400
t
~ Ideell gass
Kondenserbaregasser (damp)Condensablegases (vapour)
Ideal gases
0 1 2 3 4 5 6 7 8 9
s
0
100
200
300
400
t
~ Ideell gass
Kondenserbaregasser (damp)
0 1 2 3 4 5 6 7 8 9
s
0
100
200
300
400
t
~ Ideell gass
Kondenserbaregasser (damp)Condensablegases (vapour)
Ideal gases
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0 20 40 60 80 100Oxygen content [%]
28
32
36
40
44
Mo
le w
eig
ht
of
dry
flu
e g
as
Bituminous coal
LigniteNatural gas Mg is given by the (dry)
products resulting from the combustion reaction defined by equation 7
Mole weight of dry flue gas, Mg (kg dry flue gas/kmol)
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0 0,4 0,8 1,2 1,6Saturation line [kg water vapour per kg dry flue gas]
0
20
40
60
80
100
Tem
per
atu
re [
°C]
Bituminous coal [95% O2]
Bituminous coal [21% O2]
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Water dew point
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800P
ote
nti
al w
ater
rec
ove
ry [
To
nn
e p
er G
Wh
ele
ctri
city
]
Oxy-combustionPost-combustion
Fuel A: Lignite
85,6761,14
20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
Fuel B: Bituminous coal, Douglas Premium
67,3738,23
20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
Fuel C: Anthracite
52,2325,19
20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
Fuel D: Natural gas - conventional cycle (45%)
87,2756,4
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
Fuel D: Natural gasConventinal (solid line), 45% efficiency (base case)NGCC (dotted), 60% efficiency (base case)
87,2756,4
20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
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Water potential – either to recover or make-up
20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
85,67°C61,14°C
522,5 tonne water per MWh
444,6 tonne water per MWh
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
85,67°C61,14°C
481,9 tonne water per MWh
222,5 tonne water per MWh
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
67,37°C38,23°C
115,5 tonne water per MWh
42,5 tonne water per MWh
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
67,37°C38,23°C
78,24 tonne water per MWh
-165,5 tonne water per MWh
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
52,23°C25,19°C38,65 tonne water per MWh
-31,63 tonne water per MWh
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
52,23°C25,19°C 0,7604 tonne water per MWh
-233,5 tonne water per MWh
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20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
87,27°C56,4°C
344,5 tonne water per MWh
272,6 tonne water per MWh
SINTEF Energy Research 23
20 40 60 80 100Temperature [°C]
-800
-400
0
400
800
Po
ten
tial
wat
er r
eco
very
[T
on
ne
per
GW
h e
lect
rici
ty]
Oxy-combustionPost-combustion
87,27°C56,4°C
321,8 tonne water per MWh
79,72 tonne water per MWh
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Conclusion
Without a proper water balance, a significant amounts of make-up water may be required. For instance (Fuel B and C): post-combustion capture systems operating with bituminous coal and anthracite require make-up water corresponding to 43/66 and 32/137 t/GWh respectively, provided that the flue gas leaves the cycle at 32/45°C. If the tail-end temperature is raised to 52/70°C, the net water demand will grow to 234/784 and 166/733 t/GWh, respectively. In contrast, a similar plant operating with (Fuel A) lignite yields a surplus of 445/329 t/GWh water at 32/45°C owing to the high water content (49% in this study), whereas at 52°C the surplus drops to 223 t/GWh, and at 70°C a make-up of 383 t/GWh is required. If natural gas (Fuel D) is used in the same power cycle, assuming similar efficiency (45% LHV), a surplus of 273/172 t/GWh water will occur at 32/45°C. This is due to the higher hydrogen-to-carbon ratio of natural gas. At 70°C the situation will shift from net yield to make-up water demand of 444 t/GWh. Oxy-NG, however, will release a significant amount of water (344/260 t/GWh at 32/70°C at 45% plant efficiency, and somewhat less at 60% plant efficiency).