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CO2 CaptureStatus & Issues

Prof. Mohsen AssadiGas technology

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Outline

• Background

• Capture technologies & status

– Post-combustion

– Pre-combustion

– Oxy-fuel

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Electricity generation

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New plant capacity (VGB)

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Capture ready plants

• Not well defined! Place & performance!

• Post-combustion most suitable for

future “capture ready” plants

• Large steam extractions needed for

regeneration

• Minimum pre-investment for steam

turbine

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Various capture technologies

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Amine Scrubbing

Advantages

• Proven technology

• Known chemical process

• Ability to predict performance and solvent consumption

Limitations

• High energy consumption for solvent regeneration

• High rate of process equipment corrosion

• High solvent losses due to fast evaporation

• High degradation in presence of oxygen

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Existing plants

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Existing plants

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Pilot plants

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Status

• No full scale plants in operation yet

• More research and development needed

• Scaleable, flexible pilot plants for

validation & verification

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Chilled Ammonia (1.6 C)

• Advantages

• Lower regeneration energy with HP regeneration

• Low-temp. CO2 absorption min. NH3 emissions.

• High CO2 absorption efficiency in bubbler absorber.

• Applicable for new plants and for retrofit

• Carbonates are stable over a wide range of

temperatures & do not degrade during absorption-

regeneration

• The process uses low-grade waste heat

• Potential to capture 90% of CO2 emissions

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Chilled Ammonia

Limitations

• Ammonia volatility can be an issue.

• The pH of the ammonia solvent does not allow for

much carbonate formation.

• Slower absorption rate than MEA. Requires three

times more packing to achieve the same CO2

removal performance. A number of absorber

vessels are required, increasing capital cost and

affecting plant layout.

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Status

• 2 MWe field pilot to be operated at the

Pleasant Prairie Power Plant, Wisconsin, US

• Pilot plant under construction at

Karlshamnsverket, Sweden

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Oxy-fuel

Advantages

• Exhaust gases consist of CO2 & H2O. Separation by condensation.

• Very low NOx emissions

• Efficient O2 separation reduces efficiency penalty (AZEP, membrane)

Limitations

• Expensive air separation process with high energy demand (Cryogenic)

• New development of gas turbines needed

• CO2 recirculation for temp. control

• Condensation process needs new equipment

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Status

• High oil prices provide a market for EOR

• An old GT (TIT 780C) will be modified

(CO2 Global, Carl W. Hustad)

• Experiences to be transferred to modern

GTs

• KMB-project in Stavanger (UiS & IRIS)