Field Measurement of Amine Aerosol by FTIR and Phase Doppler Interferometry

Abstract

The emission of volatile compounds is an environmental and economic concern for CO2 capture by amine scrubbing. The condensation of amine species into aerosol is the main cause of volatile amine emissions. Current mitigation methods, including water wash, are not effective at preventing the atmospheric release of aerosol. This study focuses on the observation of aerosol at three amine scrubbing pilot plants.Fourier Transform Infrared Spectrometry (FTIR) sampling was performed in a pilot plant at the University of Texas at Austin. SO2 injection increased the emission of PZ solvent at a 1:1 molar ratio, and the injection of vaporized sulfuric acid increased amine emissions at a rate of 3 mols PZ/mol H2SO4. The slipstream pilot plant operated by the University of Kentucky utilized MEA to scrub CO2 from the flue gas stream of a coal-fired power plant. Bypassing caustic pretreatment and allowing SO2 to enter the absorber column increased MEA emissions. A 4% increase in the outlet CO2 resulted in a 10% reduction of amine emissions. A simplified water wash system was found to be ineffective at curtailing aerosol emissions.Phase Doppler Interferometry (PDI) and FTIR sampling were performed simultaneously at the National Carbon Capture Center. Using a blower between the water wash and absorber column instead of upstream of the absorber column resulted in a decrease in MEA emissions. The use of the intermediate blower instead of the upstream blower resulted in fewer, smaller aerosol drops. Decreasing the CO2 removal resulted in reduced amine aerosol emissions. Lower CO2 correlated with a lower aerosol concentration in the treated flue gas, but the aerosol sizes were significantly larger and resulted in overall increased amine emissions. Increasing the water wash temperature was found to increase average aerosol size and the amine concentration within the aerosol phase, resulting in an overall increase in amine emissions. By using the particle size distribution and aerosol concentration observed by PDI, the total liquid volume in the aerosol phase was calculated. Comparing this calculated quantity with the amine emissions observed using the FTIR allowed the approximate amine concentration in the aerosol phase to be determined.