Demonstrating solvent management technologies for an aqueous AMP/PZ solvent

Abstract

Within the transatlantic project LAUNCH, solvent management strategies are validated by test campaigns at four capture plants with an adequate plant size and in an industrial environment (3 pilot facilities with a capture capacity of up to 0.4 tCO2/h and a commercial plant with 12 tCO2/h). At the capture pilot plant at Niederaussem, which separates in 24/7 mode the CO2 from the flue gas of the adjacent 1,000 MW lignite-fired block of the power plant, three degradation control technologies with different effect mechanisms are investigated in testing campaigns with the so-called CESAR1 solvent (>14,000 testing hours with an aqueous solution of 3.0 molar (~26.74 wt.-%) 2-amino-2-methylpropan-1-ol (AMP) and 1.5 molar (~12.92 wt.-%) piperazine (PZ): adsorptive removal of trace elements from the solvent by active carbon, removal of ionic trace elements from the solvent by ion exchange and removal of NO2 from the flue gas by thiosulfate/sulfite dosing. Activation of carbon and particle filters after 5,184 and 6,048 hours testing time resulted in a removal of coloring agents, iron and nickel from the solvent. Additionally, the increase of Cl-, SO42- and NO3- concentrations could be reduced, but no clear effect on the solvent degradation rate was observed. Anionic degradation products and trace components can be effectively removed from the aged solvent by ion exchange with an anionic exchange resin. Laboratory tests with the anionic resin and three cationic resins provide promising results to remove metal ions from the solvent. As iron can be removed from the solvent using the anionic resin, but not nickel, this is a strong indication that iron is dissolved in the solvent in the form of an anionic complex, which highlights the importance of the solvent matrix when investigating the catalytic effect of metal ions on amine degradation. Despite a concentration of 175 mmol/kg thiosulfate and 32 mmol/kg sulfite and a pH value of >8.5 of a scrubbing solution in a pre-treatment scrubber, it was not possible to remove NO2 from the flue gas. Laboratory tests confirmed the effect of the pre-treatment concept. Either the mass transfer is not sufficient in the scrubber or new NO2 is formed after the pre-treatment from NO in the flue gas. This will be

Keywords: solvent management, degradation, AMP, piperazine, NO2, active carbon, ion-exchange