3-C Development fase III

Compact CO₂ Capture (3C) is a new solvent based post-combustion CO₂ capture technology based on two advanced mass transfer equipment units that aims to reduce cost and energy demand relative a conventional monoethanolamine (MEA) based absorption/desorption process. The first unit is a spray absorber channel called Channel Integrated Treatment (CIT) and the second a Rotating Desorber Wheel (RDW). The combination of these two enables the use of more viscous solvents with a higher carrying capacity and a lower steam demand than conventional 30 w% MEA. With certain assumptions, cost reductions could be possible since the CIT has no packings and the RDW is relatively compact. Solvent degradation in the RDW at high temperatures is assumed to be controlled by a lower residence time of the solvent in the RDW.

During the spring of 2014, 18 test campaigns were performed on a pilot-scale RDW with in total around 160 individual set of variables. The results of these experiments were used in system calculations of combined cycle gas turbines with capture. They have shown a normalized RDW specific reboiler duty (SRD) of 3.6 MJ/kg CO₂ for about 70 w% MEA and 3.2 MJ/kg CO₂ for about 85 w% MEA at rich loading 0.45 mol/mol and lean loading 0.25 mol/mol. If the rich loading could be increased this will reduce the SRD theoretically even more. This is a significant saving from reference cases with 30 w% MEA and a conventional stripper that demand 3.8-4.2 MJ/kg CO₂, based on measurements from pilot units at TCM and Esbjerg. The reduced energy demand could lead to a ~1% percentage point increase in energy efficiency of large scale modern combined cycle gas turbine with amine based CO₂ capture. Tests of solvent degradation could not yet confirm whether it is possible to get an acceptable solvent stability at the high temperatures in the RDW.

An absorber with sufficient maturity that can operate with 70-85 w% MEA solvent is needed for the RDW concept but does currently not exist. Furthermore, the technical uncertainties around the CIT absorber also suggest that alternative absorber concepts should be identified for realizing the potential of the RDW.