Solvent Degradation and Emissions From a CO₂ Capture Pilot At A Waste-to-energy Plant

Degradation and emissions of amine-containing solvents from CO₂ capture plants are important to address as we are getting closer to full-scale deployment. Solvent degradation and air emissions from CO₂ capture with 30 wt% monoethanolamine (MEA) were monitored at a mobile capture pilot, treating flue gas from a waste-to-energy facility in Denmark. The release of nitrosamines and nitramines was shown to be below the detection limit. Preliminary results showed that the installation of an acid wash removes gaseous degradation products from the depleted flue gas by up to 83% for MEA. However, a more in-depth investigation of the acid wash performance is needed to fully make any conclusions. The release of CO, NO, NO₂, SO₂, NH₃, and HCl was monitored over several days. Results showed that the release of these components in the depleted flue gas is affected by both the temperature in the wash tower and the process configurations. The emissions of CO, NO, NO₂, SO₂, NH₃ and HCl in the CO₂ product stream were below 5 mg/m³. Heat stable salts accumulate over time in 30 wt% MEA with formate and acetate being the main degradation products. Accumulation of iron in the solvent did not exceed 10 mg/L during the 4 month campaign. The solvent degradation and emission results obtained in this study create a solid basis for understanding potential solvent emissions to the environment from waste-to-energy plants. Currently, the accumulation of heat stable salts in amine-based solvent seems to be the main challenge.