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Chalmers University of Technology
Oxyfuel combustion
– state of the art in development
Filip Johnsson
Department of Energy and Environment
Chalmers Energy Conference
January 26-27, 2011
Chalmers University of Technology
The basic principle of oxy-fuel combustion
In PC typically 2/3 of the flue gas is recirculated (RFG)
Chalmers University of Technology
Oxyfuel combustion
• Based on commercially available technologies
• Yet, the entire process is different from air firing
– Radiation
– Chemistry
– Mixing
Imposes both unresolved issues and new
opportunities
Chalmers University of Technology
Planned and proposed CCS demos
Chalmers University of Technology
Pulverized
Lignite-fired
2x865 MWel
el=0.42 w/o capture
el=0.34 w capture
Comissioned in 2000
10 million tonnes CO2/year
Process evaluation (2002) - Lippendorf
Chalmers University of Technology
o2
N2
o2
O2
123
4
5
6
7
8
Air inlet
9
10
11
1413
12
16
15
20
19
18
17
23
22
21
26
2524
28
27
30 29
CO2
out
31
B
C
32
A
1. Air compressor
15. Compressor unit 1, 30 bar
14. Flue gas cooler
13. Flue gas condensation unit
12. TEG heat exchanger
11. Economizer
10. Super heater
9. Boiler
8. Destillation column
7. Expansion turbine
6. Heat exchanger
5. Molecular sieves
4. Evaporative cooler
3. Direct contact air cooler
2. Compressor cooling
28. District heating
27. Cooling tower
26. Condenser
25. LP Steam turbine
24. IP Steam turbine
23. HP Steam turbine
22. High pressure pump
21. Subcooler
20. Gas/Liquid separator
19. Heat exchanger (CO2/CO
2)
18. CO2
condenser
17. Compressor unit 2, 58 bar
16. TEG
31. Nitrogen heater
30. Feed water preheater
29. Feed water preheater
Process and cost study of a large scale lignite fired O2/CO2 power plant
Proposed O2/CO2 scheme:( 99.5% reduction in CO2 emissions to the
atmosphere)
Andersson et al.(2003) VGB Power Tech Journal No 10
Chalmers University of Technology
Chalmers
100 kW oxyfuel
PC test unit
100kW Lignite flame
27% oxygen
Chalmers University of Technology
Vattenfall 30MW Schwartze pumpe oxy-fuel pilot plant
Chalmers University of Technology
• Experimental experience in general
• Reaction chemistry (NOx, SOx)
• Heat transfer
• Heat balance in oxy fuel fired fluidized-beds
• Material issues
• Primary vs secondary measures for flue gas cleaning (especially
with respect to NOx)
• 2nd generation oxyfuel plants – high temperature
• CFD simulations
• Process concept/process integration
• Novel ASU technologies
• Development of modeling tools for reliable design and scale up of
process
R&D oxyfuel combustion
Chalmers University of Technology
Development of CFD tools. Example, Chalmers 100 kW OF27
- Four global reaction mechanisms compared with
measurements
Dis
tance fro
m c
entr
elin
e [
mm
]
Distance from burner [mm]
OF
27
-400
-200
0200
400
0
500
1000
1500
2000
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
• Measurements
• 3-step mechanism
• 4-step mechanism
• 6-step mechanism
• 4-step2mechanism
Temperature
Chalmers University of Technology
New conditions new opportunities
Table 1. Rough overview of properties of the flue gas in an oxy-fuel power plant (see Figure 1 for stream
numbers). Stream 1 2 3 4 5 6 7
Pressure (bar) 1 1 1 30 30 100 1
Temperature (°C) 300 300 20 20 -30 20 20
Mass Flow 1 1/3 1/3 1/3 1/4 1/4 1/25
Volume Flow 1 1/3 1/7 1/200 1/900 1/1000 1/40
Phase Gas Gas Gas Gas Liquid Fluid* Gas
* Supercritical fluid.
Normann (2010)
Chalmers University of Technology
Metso Power
4 MW CFB Oxyfuel (start mid2010)
Oxyfuel in fluidized-bed combustion
Chalmers University of Technology
Oxyfuel in fluidized-bed combustion
Chalmers University of Technology
Share of heat extraction normalized by the total thermal power
State of the art 278 MWth CFB boiler used, 37 m tall furnace, 15x6 m furnace
cross section
Chalmers University of Technology
Key features/problems in FB combustion
• Ratio of mixing and fuel convesrsion
• Solids segregation
• Dynamics of mixing
200 m2 bed surface (235 MW CFB Turow)
Air distributor
Chalmers University of Technology
-8
-6
-4
-2
0
2
4
6
8
-4-2
02
4
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
x [m]
y [m]
Char
concentr
ation [
kg/k
g]
Char concentration in large-scale
(>200MW) CFB boiler
Modeling for prediction of heterogeneous volatile and char
combustion - distribution over the cross section depending
on fuel type, fuel feeding location and operational conditions
(Pallarès & Johnsson, work in progress)
Fuel feed points
Chalmers University of Technology
Oxyfuel combustion for CO2 captureResearch and development
Chalmers 100kW
research plant
Vattenfall 30MW
pilot plant
Jänschwalde 250 MW
demonstration plant
Commercial
plant
2010 2015 2020
Chalmers University of Technology
Summary of results• The process (PC) has been successfully demonstrated at a
technical scale in a 100 kW unit
• The 100 kW test unit has been operated with gaseous as well as solid fuels
• Tests have been performed during more than 1,000 hours of operation on both gas and coal (German lignite)
• High carbon dioxide concentration levels performed under well controlled conditions, and negligible air leakage
• Detailed characterization of oxy-fuel flames have been performed with a focus on their composition and radiativeheat transfer characteristics
• Tests have been conducted at the 30MW pilot plant (PC) in Germany (and in 5MW CFB pilot plant in Finland)
• Results give an extensive base for continued development at pilot scale and demonstration scale
