FLUE GAS PROCESSING - IEAGHG

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: [email protected] Web: www.SINTEF.no

SINTEF Energy Research

Trondheim, Norway

mailto:[email protected]

mailto:[email protected]


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)

2


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


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

5


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

6


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

7


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

8


The mole weight of water vapour (Mv) is 18 kg/kmol.


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)


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]

11

Water dew point


Oxy-combustion CO2-capture scheme


Post-combustion CO2-capture scheme


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]


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]


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]


Fuel D: Natural gas - conventional cycle (45%)

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]


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]

15


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]


85,67°C61,14°C

522,5 tonne water per MWh



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]


85,67°C61,14°C




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]


67,37°C38,23°C




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]


67,37°C38,23°C


-165,5 tonne water per MWh


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]


52,23°C25,19°C38,65 tonne water per MWh



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]


52,23°C25,19°C 0,7604 tonne water per MWh



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]


87,27°C56,4°C




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).

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