Chemical absorption / desorption process

The chemical absorption process has been used since the 1930s to capture CO₂ from ammonia plants for food applications. Today it remains the most mature process for capturing CO₂ in large quantities.


Would you be interested to discuss your CO₂ Capture, Utilization and Storage plan with one of our experts?


Several solvents are available for the CO2 capture by chemical absorption. The most used solvent is based on the primary amine monoethanolamine (MEA) or/and secondary/tertiary amines blends with, most of the time, addition of promoters like piperazine. From its earlier experience with CO2 capture installations and from its know-how in gas liquid absorbers, ANDRITZ will select the most appropriate solvent blend for a given CO2 concentration in the flue gas and a targeted removal rate. If an alternative solvent is required, ANDRITZ can also design a solution based on the customers´ preference as an EPC-contractor.


As indicated in the process flow sheet, for an amine-based solvent, the CO2 rich flue gas from the industrial process first enters a pre-scrubber where it is, on one hand, cooled down (or quenched) and, on the other hand, further treated to remove certain contaminants (acid gases, particulate matter, …) which would degrade the solvent.

The flue gas then passes into the absorption unit (or absorption column) where the CO2 is continuously absorbed (or scrubbed) by the solvent. The absorption process utilizes the reversible chemical reaction of CO2 with the solvent. The CO2 lean and clean flue gas leaves the top of the absorber towards the stack. The CO2 rich solvent is transferred to the desorption unit (or stripper). Hot and partly fresh solvent from the reboiler enters the desorption unit causing the CO2 to be stripped out of the solvent. As a result, a pure CO2 stream is collected at the top of the stripper. The CO2 lean solvent is then being regenerated and circulated back to the absorber. The pure CO2 stream is further processed, to the required purity, before being compressed, transported or stored for future use (Enhance Oil Recovery, chemical synthesis, geological storage, …).

The energy requirements for the regeneration of the solvent (heat of desorption, sensible heat and heat of vaporization) and the proper energy integration of the CO2 capture unit into the industrial process are key features of ANDRITZ CO2 capture offering. Depending on the CO2 concentration in the flue gas, the required amount of CO2 to be captured and other site-specific conditions (steam availability, steam pressure, on-site CO2 storage, …), ANDRITZ will design a unique solution securing the lowest operating costs for removing the CO2 from the flue gas.

The key features of ANDRITZ amine based chemical absorption / desorption process are:

  • Low temperature absorption (30 – 50 °C)
  • High temperature desorption (110 – 130 °C)
  • Closed Loop operation
  • Advanced amines for reduced energy consumption
  • Pre-Treatment for quenching, removal of acidic pollutants and particles
  • 3 – 4 bar steam required for desorption
  • Reclaiming necessary to avoid high amine losses
  • Heat recovery for district heating; Heat Pumps for steam generation
  • CO2 compression and/or liquefaction as required by customers
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