Post-Combustion Capture
Post-combustion carbon capture is the most common and widely used process. In this method, a solvent is used to separate CO2 from other gases in the flue stack after combustion of the fossil fuel. The most common solvent is chilled ammonia; however, other selective amines are also used. This process is well developed and has existed for several decades. The process diagram below outlines how post-combustion capture works.
The Process:
- After the fossil fuel energy source is combusted with air, the flue gas is cooled and treated to remove particulate matter, SO2, NO2 and other trace gases.
- Once cooled, the gas enters a contact absorber which consists of a liquid solvent that is typically an aqueous amine solution (usually a monoethanolamine). The amine solution absorbs the CO2.
- The CO2-rich solution is then sent to a stripper where the CO2-rich amine is separated into two separate gases: the pure amine gas, which is recycled back into the stripper, and a concentrated CO2 stream.
- The CO2 stream is then dehydrated, compressed and transported to its final storage destination.
