CO2 capture by antisublimation

1
CO2 capture by antisublimation

• On going actions - Research
• - Improvements of energy efficiency of low
  temperature
• Refrigeration system
• - Integration of flue gas cleaning and CO2
  capture
• On going actions Demonstration
• Initial engineering of 1 to 10 t/hr CO2 capture
  demonstrator

• D. Clodic
• CEP Ecole des Mines de Paris
• French Norvegian CO2 seminar
• 22nd 23rd November 2007

2

• Needs Research
• - Laboratory with expertise in 2 phase flow
  expanders
• - simulation tools for high speed centrifugal
  compressor
• Needs Demonstration
• Lesson learnt from first demonstrators
• Projects to be launched
• follow up of demonstrators
• annual update of research and demonstration
  projects.

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The CO2 capture process

• Flue gas cooling down to the CO2 condensing
  temperature

AB Sensible Cooling BC Capture/
Anti-sublimation CD Energy recovery/
Sublimation DE Energy recovery/ Fusion
LV
V
L
- 56.6C, 520 kPa
S
SV
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Energy recovery from CO2 sublimation and fusion

• The energy recovered from the CO2 sublimation and
  fusion improves significantly the global energy
  efficiency of the system.
• The frosting-defrosting process is performed
  alternatively on two evaporators, one frosting
  while the other is defrosting.

Layout of the CO2 capture system.
5
The operational scheme of the CO2 capture system
by anti-sublimation
CS1 60 23C CS2 23 (-15)C CS3 (-15)
(-40)C FF (-40) (-90C)
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Low Temperature Frosting Evaporators

• CO2 is frosted on the heat exchanger fins.
• The cooling capacity at about 120C is delivered
  by the 4-stage Integrated Cascade.
• The normal boiling points (NBP) of the components
  of the refrigerant blend are staged from the
  ambient temperature down to the lowest
  temperature level.
• At the same evaporating pressure, the higher NBP
  refrigerants are in liquid state and are
  evaporated in order to partially or fully
  condense the lower NBP components.
• The IC should be adapted to operate under any
  ambient conditions.

The 4-stage integrated cascade
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CO2 capture by anti-sublimation mock-up
A first mock-up has been built and series of
tests have been performed in order to demonstrate
the feasibility of the anti-sublimation CO2
capture process and evaluate its efficiency.
Test benches for CO2 and water captures
CO2 frosting on the evaporator fins
Liquid CO2 after defrosting
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Demonstration of CO2 capture by anti-sublimation
for both High and Low initial CO2 concentrations
Evolution of the CO2 concentration at the
evaporator outlet for a 3 initial CO2
concentration.
Evolution of the CO2 concentration at the
evaporator outlet for a 13 initial CO2
concentration.
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3900 h test bench
3900 h of automated operation with several
refrigerant blends, several CO2 capture
concentrations and CO2 capture efficiencies