CO2 capture ready options for coalfired power plants

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CO2 capture ready options for coal-fired power
plants

Kay Damen
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Rationale

• Basis Draft Study on CO2 capture ready plants
  commissioned by the IEA GHG
• Application of environmental permits for various
  coal-fired power plants
• No investments in CO2 capture are to be expected
  in the absence of economic incentives or
  legislation
• How can we assure that plants can be retrofitted
  with CO2 capture in a later stage?

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Capture ready interpretations

• Considerations, measures and investments (mostly
  spatial and technical by nature) that enable a
  power plant to be retrofitted with CO2 capture
  (and storage) in a later stage and still be
  economical to operate
• As a minimum, a capture-ready plant should have
  eliminated all the factors that would prevent a
  retrofit taking place

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General issues (1)

• Access to CO2 storage reservoir
• Plan for CO2 transport
• Space should be available for addition of plant
  items (CO2 capture, compressors, piping), access
  to existing plant items, storage of equipment
  during construction
• Auxiliary plant should be sized to meet ultimate
  demand (with capture) or be developed with a
  costed strategy to expand initial installation
• Possibilities for integration

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General issues (2)

• The design should either minimise significant
  change in major items of equipment when capture
  is fitted or have a clearly identified and costed
  strategy identified by which necessary changes
  could be implemented, accounting for downtime
• Utilisation of any near-zero cost options for
  increasing the flexibility for subsequent plant
  upgrades

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Dilemma of technological progress

• Further improvements in CO2 capture technologies
  are to be expected
• Hence investments incurred now may appear
  obsolete at the time the plant is retrofitted (or
  are not economically justified)
• Plan for retrofit should be based on
  state-of-the-art technology and account for
  impacts of future developments

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Capture ready issues PC post-combustion capture
(1)

• Boiler. Minimising impact of CO2 capture by
  selecting high-efficiency boiler (ultra
  supercritical conditions).
• FGD. SO2 concentration limits in the flue gas of
  10 mg/Nm3 for amines. Solutions
• Install highly-efficient FGD right away
• The initial FGD may have to be capable of being
  upgraded
• Add additional polishing unit
• Other considerations SO2 concentration pipeline
  and storage (EOR)

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Capture ready issues PC post-combustion capture
(2)

• Steam cycle. Extraction of low-pressure steam
  from the IP turbine exhaust (IP to LP crossover
  pipe). Solutions
• Remove 1 LP turbine () lowest energy penalty
• (-) requires accurate prediction of steam demand
• Throttled LP turbine (valve to keep crossover
  pressure constant) () flexible in steam
  extraction (-) throttling losses
• Select turbines that operates well under
  different conditions than nominal specifications
  are can be adapted (flexibility, intermediate
  energy loss)
• Add back-pressure turbine (no capture ready
  option)

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Capture ready issues IGCC pre-combustion
capture (1)

• Combustion. H2 has other combustion properties
  than syngas, modification of GT burners (fuel
  nozzles). To avoid NOx emissions increase due to
  higher flame T, N2 or steam must be injected. N2
  from ASU (additional compressor)
• De-rating. LHV fuel is reduced when shifting to
  H2. Over dimension coal logistics, ASU, fuel
  pipes to GT. Add additional gasifier.
• Steam cycle. Less steam available for expansion,
  select turbines that operate well under
  non-nominal conditions. HRSG performance will
  also change due to change in radiative properties
  of the combustion products

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Discussion

• Apart from space requirements etc, the issue of
  capture ready is mainly study obligation?
• Capture ready issues should be restricted to
  capture and not transport and storage?
• What is a credible sink? To what extent should
  the suitability and availability of storage
  reservoir be studied/accounted for?
• Additional impacts, energy requirements and costs
  IGCC are lower than for PC. Does that make IGCC
  more capture ready than PC?

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