IECM 12.0 beta User Manual > Modules Included with the IECM > Integrated Gasification Combined Cycle (IGCC) Plant > SET PARAMETERS > CO2 Capture, Transport & Storage > 2. Selexol CO2 Capture >

Retrofit or Adjustment Factors

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See Retrofit or Adjustment Factor Inputs for an explanation of retrofit costs. The Selexol CO2 capture system has the following capital cost process areas:

•Absorbers: The Selexol absorbers use physical absorption to capture CO2. Because the solubility of CO2 in the solvent is proportional to its partial pressure in the gas phase, the performance of the absorbers increases with increasing CO2 partial pressures.

•Power Recovery Turbines: The CO2-rich solvent from the absorber is fed into a set of hydraulic power recovery turbines to recover some of the pressure energy before it is fed into the slump tanks.

•Slump Tanks: A slight pressure drop in the slump tanks releases a majority of H2 and CH4 and a small amount of CO2. This process area enriches the CO2 concentration.

•Recycle Compressors: Gases from the slump tank are recycled back into the absorber. A compressor is used to compress the gases to the operating pressure of the absorber.

•Flash Tanks: CO2 is released in multiple stages by reducing the pressure in successive flash tanks. Three flash tanks are typically used in a single train. The staging process reduces the power of CO2 compression later.

•Selexol Pumps: The CO2-lean solvent is pumped back to the absorber operating pressure by a Selexol circulation pump.

•Refrigeration: CO2-lean solvent must be cooled to the absorber operating temperature before being returned to the absorber vessel. A refrigeration unit is used to reduce the temperature of the solvent.

•CO2 Compressors: CO2 released from the first two flash tanks is compressed to the flashing pressure of the first flash tank. The two CO2 streams are then combined and sent to the final product compressors.

•Final Product Compressors: The product CO2 must be separated from the water vapor (dried) and compressed to liquid form in order to transport it over long distances. The multi-stage compression unit with inter-stage cooling and drying yields a final CO2 product at the nominal pressure of 2000 psig. This area is a function of the CO2 flow rate.

•Heat Exchangers: This process area considers miscellaneous heat exchangers used in the overall process.