Fourth Annual Conference on Carbon Capture & Sequestration
Developing Potential Paths Forward Based on the Knowledge, Science and Experience to Date
Capture and Separation- Oxyfuel Combustion
CO2 Compression Units for Oxy-Fuel CombustionKourosh E. Zanganeh, Ahmed Shafeen, Carlos Salvador, Murlidhar Gupta, and Bill
Pearson
Fossil Fuels and Climate Change Group,CANMET Energy Technology Center, Natural Resources Canada, 1 Hannel Drive, Ottawa, ON, K1A 1M1, Canada
May 2-5, 2005, Hilton Alexandria Mark Center, Alexandria Virginia
Outline
• Fuel combustion and CO2 capture pathways• Oxy-fuel Combustion• CO2 compression and capture processes
– Once-through process– Autorefrigeration (Fluor process)– Novel CETC process
• Pretreatment and moisture separation• Process modeling and simulation• Results• Conclusions
Capture Pathways
Air-combustion
Coal
NG
Biomass
Petcoke
Gasification
Oxy-combustion
CO2 Capture
Power & Heat
CO2 (>90 bar) Transport for
Storage
O2
CO2 Capture
Combustion Power & Heat
Power & Heat
CO2 Capture & Compression
Flue gas
5-15% CO2
@ 1 bar
Syngas
20-40% CO2
Flue gas
>80% CO2
@ 1 bar
CO2
CO2
CO2 (~20 to 50 bar)
H2
CO2 Compression
CO2 Compression
> 99%@ 1bar
Pump
Schematic of Oxy-Fuel Combustion for Power or Heat Generation
Recycled Flue Gas
Air SeparationUnit
O2
Gas Purification
Fossil fuelcombustion
Power or Heat
N2
StorageCO2
Compression
1/5 exit gas volume relative to airCO2 at 80-98% by volume
Other pollutants and/or water
For process heaters, furnaces and boilers
An Idealized Thermodynamic Path of Compression, Cooling, and Pipeline Operations
for CO2
Mohitpour M., Golshan H., and Murray A., Pipeline Design and Construction: A Practical Approach, New York, American Society of Mechanical Engineers Press, 2000
CO2 Phase Diagram
http://www.acpco2.com/index.php?lg=en&pg=2121
Conventional Multistage Compression
Autorefrigeration Separation of Carbon Dioxide (Fluor Process)
PretreatmentModule
Vent Module
PumpingModule
Expander &Separator
Module
2nd StageCompression
Module
1st StageCompression
Module
ToAtmosphere
(Stack Flue Gas)
CO2 Product Stream
Stream 1 Stream 5
Stream 8
Stream 3
Stream 4
Stream 7
Stream 6Stream 2Feedgas
(Extract Energy)
(Extract Energy)
(H2O) (H2O)
Novel CETC Process
• Proprietary process• Some process simulation results will
be presented• Comparison between the results:
– CETC Compression process versus Fluor Autorefrigeration/separation process
Assumptions for Simulation
• Same baseline design conditions • Inlet pressure and temperature
– 1 bar, 40 0C• Vent pressure and temperature
– 6 bar; above dew point• Product pressure and temperature
– Optimum pressure is derived from the simulation at -5 0C
Feed Gas Composition
Properties Unit Compressor InletFeed gas-1 Feed gas-2 Feed gas-3
Temperature 0C 40 40 40Pressure bar 1 1 1Flow Rate kg/hr 181.0 181.0 181.0Composition
CO2 - 0.7443 0.800 0.8467H2O - 0.0667 0.070 0.0667O2 - 0.0335 0.030 0.0304N2 - 0.1355 0.0845 0.0519SO2 - 0.0012 0.005 0.0014Ar - 0.0183 0.010 0.0024NO - 0.0005 0.0005 0.0005NO2 - 0.0001 0.0001 0.0001
Mole Fraction Mole Fraction Mole Fraction
Pretreatment and Moisture Separation• The extent of pretreatment depends on:
– Design considerations( ice formation, corrosion, metal properties, etc.)
– Cost (cleaning cost, additional energy penalty, material cost, etc.)
– Application (EOR, Storage, ECBM, etc)
Feed Gas Inlet Temperature to 1st StageTemp Vs Moisture remained in Line
00.5
11.5
22.5
33.5
44.5
5
-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40
Inlet Temp ( 0C)
Moi
stur
e (k
g/hr
% Moisture remaining with increased Cooling
00.10.20.30.40.50.60.70.80.9
11.1
0 1 2 3 4 5 6 7
Cooling Energy Demand (kW)
Fina
l moi
stur
e/In
itia
Moi
stur
e
-25-20-15-10-50510152025303540
Inle
t Tem
pera
ture
(0 C)
Moisture remain/Initial Moisture Cooling Temperature
Process Modeling and Simulation
• Process Modeling– Both processes were modeled in HYSYS– Same initial feed gas characteristics and final product
conditions.– Product CO2 purity equal or above 95%
• Processes Optimization– CO2 recovery– Energy requirement– Stage pressure and recycle ratio
Comparison of Results
0.4
0.5
0.6
0.7
0.8
Ener
gy re
quire
men
t (kW
-hr/k
g)
Fluor Process CETC Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
60
70
80
90
100
CO 2 r
ecov
ery
rate
(%)
Fluor Process CETC Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
40
60
80
100
120
2nd
Stag
e Pr
essu
re (b
ar)
Fluor Process CETC Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
80
85
90
95
100
Purit
y (%
)
Fluor Process CETC Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
Fluor Process at Different Optimized 2nd
Stage Pressure
0.4
0.5
0.6
0.7
0.8
0.9
Ener
gy re
quire
men
t (kW
-hr/k
g)
Optimized Fluor Process Optimized CETC Process Fluor w /CETC pressure
Feed Gas 1 Feed Gas 2 Feed Gas 340
60
80
100
120
2nd
Stag
e Pr
essu
re (b
ar)
Fluor Process CETC Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
80
85
90
95
100
Purit
y (%
)
Optimized Fluor Process Optimized CETC Process Fluor w /CETC pressure
Feed Gas 1 Feed Gas 2 Feed Gas 3
0
20
40
60
80
100
CO 2 r
ecov
ery
rate
(%)
Optimized Fluor Process Optimized CETC Process Fluor w /CETC pressure
Feed Gas 1 Feed Gas 2 Feed Gas 3
Impurities Distribution in Vent Stream
60
70
80
90
100
F luo r Process C ET C Process
F eed Gas 1 F eed Gas 2 F eed Gas 3
0
2
4
6
8
10
F luor Process CETC Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
50
60
70
80
90
100
F lu o r Pro ce ss C ET C Pro ce ss
F eed G as 1 F eed G as 2 F eed G as 3
0
2
4
6
8
10
F luor Process CET C Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
Impurities Distribution in Product Stream
0
10
20
30
40
50
60
70
80
90
100
F luor Process CET C Process
Feed Gas 1 Feed Gas 2 Feed Gas 3
0
10
20
30
40
50
60
70
80
90
100
F lu o r Pro ce ss C ET C Pro ce ss
F eed G as 1 F eed G as 2 F eed G as 3
0
10
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
10 0
F lu o r P ro ce ss C E T C P ro ce ss
F eed G as 1 F eed G as 2 F eed G as 3
0
10
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
10 0
F lu o r P ro c e s s C E T C P ro c e s s
F eed G as 1 F eed G as 2 F eed G as 3
Conclusions• Many factors impact the design of a CO2 compression
unit for oxy-fuel combustion• The impact of impurities in the process design is an
open area for research• The once-through CO2 compression process is well
established and easy to implement.• Autorefrigeration process performance is superior to
the once-through compression process• Process simulation results shows that CETC process
offers significant improvement over Autorefrigerationprocess. – Improved energy efficiency at product purity above 95% – Lower liquid product pressure before the pumping module– Higher recovery rates
