Post-combustion capture

Post-combustion capture refers to the removal of carbon dioxide (CO₂) from a power station flue gas prior to its compression, transportation and storage in suitable geological formations, as part of carbon capture and storage. A number of different techniques are applicable, almost all of which are adaptations of acid gas removal processes used in the chemical and petrochemical industries. Many of these techniques existed before World War II and, consequently, post-combustion capture is the most developed of the various carbon-capture methodologies.

Post-combustion capture plant should aim to maximise the capture of CO₂ emissions from combustion plant and delivery it to secure sequestration in geological strata. Typically, a plant will aim to achieve a CO₂ capture rate of >95%. To meet the required specification, the following should be monitored:

• CO₂ mass balance
• CO₂ in fuel combusted
• Total CO₂ capture level (as a percentage)
• CO₂ released to the environment
• CO₂ quality

CO₂ can be transported either as gas phase at about 35 barg or as dense phase at 100 barg. The CO₂ stream should meet or exceed gas quality standards.

CO₂ absorbents include primary amines which require more heat for regeneration than secondary amines However, secondary amines may form nitrosamines with Nitrogen oxides NOx in the flue gases. All non-solvent constituents must be removed from the solvent. Pilot or full-scale tests using actual flue gases and solvents may be performed.

Calcium looping is a promising second generation post-combustion capture technology in which calcium oxide, often referred to as the "sorbent", is used to separate CO₂ from the flue gas. The ANICA project focuses on developing a novel indirectly heated carbonate lopping process for lowering the energy penalty and CO₂ avoidance costs for CO₂ capture from lime and cement plants.

External links

• "Carbon Capture and Storage at Imperial College London". Imperial College London. Archived from the original on 24 April 2017.