SECOND INTERNATIONAL CONFERENCE ON INDUSTRIAL GAS TURBINE TECNHOLOGIES BLED, SLOVENIA 293042004

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SECOND INTERNATIONAL CONFERENCE ON INDUSTRIAL GAS
TURBINE TECNHOLOGIES BLED, SLOVENIA 29-30/4/2004

• CO2 Sequestration for the Combined Cycle Power
  Plant with Integrated Low Temperature Heat
• E. Kakaras1, R. Leithner2, A. Doukelis1, D.
  Giannakopoulos1,
• A. Koumanakos1, N. Aronis2
• Presentation Dr. A. Poullikkas, EAC
• 1National Technical University of Athens, LSB
• 2Technical University of Braunschweig, IWBT

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OUTLINE OF PRESENTATION

• INTRODUCTION
• LOTHECO CYCLE
• CO2 CAPTURE TECHNOLOGIES FOR POWER PLANTS
• SEPARATION OF CO2 FROM FLUE GAS WITH MEA
  SCRUBBING
• TEST CASE ASSUMPTIONS AND SIMULATION RESULTS
• CONCLUSIONS

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INTRODUCTION

• Possibilities and advantages from integrating CO2
  sequestration technologies in the LOTHECO cycle
  concept by comparison with a standard combined
  cycle
• The work presented here has been performed within
  the framework of the EC contract
  ENK5-CT2000-00063. The consortium consisted of
  Public Power Corporation of Greece, Technische
  Universitaet Braunschweig, National Technical
  University of Athens, Technische Universitaet
  Wien, Imperial College of Science Technology and
  Medicine, Fichtner GmbH Co KG, Universitatea
  Politehnica Timisoara, Sofia Energy Centre Ltd.,
  Frederick Institute of Technology, Electricity
  Authority of Cyprus and Hyperion Systems
  Engineering Ltd.

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LOTHECO CYCLE
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DESCRIPTION OF THE LOTHECO CYCLE

• Utilisation of low-temperature waste heat or
  solar heat to evaporate water injected into the
  compressed combustion air of the gas turbine.
• Water-in-air evaporation takes place at the
  vapour partial pressure and, therefore, at low
  temperatures (from below 100C up to 170C).
• High heat transfer rate in the evaporator, due to
  the higher heat transfer enhanced by water
  evaporation.
• Unlike other Wet Gas Turbines, the bottoming
  steam cycle remains unchanged.
• Compression of stoichiometric airflow, leading to
  reduced compressors size and power consumption
  compared with conventional CCs.
• Very low NOx emissions, due to the high water
  vapour content in the combustion air and the low
  combustion temperatures.

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CO2 CAPTURE TECHNOLOGIES FOR POWER PLANTS

• The commercial or under development CO2
  sequestration technologies for power plants are
  divided into three broad categories
• Separation of CO2 from waste gas
• Combustion in O2 instead of air
• Production of a carbon free fuel
• Separation of CO2 from waste gas through
  absorption is a mature commercially available
  technology
• Absorption processes are classified as chemical
  and physical.
• - Chemical absorption flowlt150 m3/s, CO2
  partial pressureslt7 bar
• - Physical absorption flowgt150 m3/s CO2 partial
  pressuresgt7 bar
• The most common chemical solvents utilised are
  the alkanoamines (MEA, DGA, DEA, DIPA, TEA, MDEA
  ammonia or hot potassium carbonate.

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SEPARATION OF CO2 FROM FLUE GAS WITH MEA SCRUBBING

• The most commercially successful technique is the
  wet scrubbing process with chemical absorption by
  monoethanolamine (MEA). CO2 is absorbed from the
  flue gas by the liquid solvent in an absorber
  (40-60ºC). In the stripper, the charged amine
  solution is heated with steam to 100-150 ºC, to
  strip off CO2.
• MEA scrubbing provides CO2 recovery rate of 98
  and product puritygt99.
• Most systems use an aqueous solution of 15-25 wt
  MEA, due to corrosion.
• Required heat for regeneration of the absorbent
  4 MJ per kg of recovered CO2 provided by steam
  extraction at ca. 5 bars.
• Energy for compression of the flue gases and
  pumping of the amine solution ca. 0.11 MJ per kg
  of CO2 captured.
• When applied in coal-fired power plants, the
  scrubbing process reduces the steam flow in the
  LP ST by ca.2/3. As a result, power output is
  reduced by 20 and the plant efficiency by 11-14
  percentage points.
• For a typical plant, the economical recovery is
  85 for 3 CO2 in the flue gas and 90-92 for 8
  CO2 in the exhaust gas.

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AMINE FLUE GAS PROCESSING OPERATION
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TEST CASE ASSUMPTIONS

• The LOTHECO concept is compared with a commercial
  CC (Alstom KA10C)
• The developed model provides a picture of the
  overall performance of a CC power plant and of
  the LOTHECO CC with integration of a MEA
  scrubbing CO2 capture system.
• The heat consumed for the regeneration of the
  reach solution is provided in the form of
  low-pressure steam extraction. The extraction
  pressure is 4.6 bar and the temperature is 169 ºC
  and 171.9 ºC for the LOTHECO CC and the standard
  CC respectively. The steam provides its latent
  heat for the regeneration and the condensate is
  returned after the LP feed-water pump. The
  stripper column thermal consumption is 4MJ/kg of
  CO2 removed ca.1.7 kg/kg CO2.
• The flue gases at the outlet of the HRSG are
  compressed to 1.3 bar before entering the
  scrubber and cooled to 25 ºC to condense the
  water vapor. The final pressure of 150 bar is
  chosen in order to facilitate the transportation
  and sequestration of CO2.
• CO2 recovery from the flue gases is assumed to be
  90 in both cases.

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SIMULATION RESULTS FOR ALSTOM KA10C
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SIMULATION RESULTS FOR LOTHECO CC
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COMPARISON BETWEEN KA10C AND LOTHECO CC
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COMPARISON BETWEEN KA10C AND LOTHECO CC
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COMPARISON BETWEEN KA10C AND LOTHECO CC WITH CO2
SEQUESTRATION

• LOTHECO CC has a lower flue gas flow at the inlet
  of the scrubber with a higher CO2 concentration,
  resulting in less shaft power for the blower used
  for compression of the flue gases.
• LOTHECO CC has lower additional shaft power
  consumption for cooling the flue gases, since the
  gas cooler is already incorporated in the LOTHECO
  scheme. This is also an advantage concerning
  additional capital cost for integration of the
  CO2 sequestration scheme
• The power consumed for compression of the final
  product for transportation and sequestration, as
  well as the thermal power requirements for the
  rich solvent regeneration is the same for both
  cases, since the amount of CO2 recovered is the
  same.

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CONCLUSIONS

• The advantages of the LOTHECO natural gas-fired
  Combined Cycle concept have been demonstrated by
  comparison with a standard combined cycle
  integrating CO2 sequestration via amine scrubbing
• Integration of the amine scrubbing process in the
  LOTHECO CC plant results in a much smaller
  penalty on the power output and efficiency than
  in a standard CC plant.