Impacts of aerosol nuclei on amine emissions
16 Pages Posted: 4 Apr 2019 Last revised: 27 Oct 2020
Date Written: 2018
Amine emissions are an environmental and economic concern for CO2 capture by amine scrubbing. Aerosol nuclei, including hydrolyzed SO3 and fly ash, can lead to amine aerosol emissions. Aerosol grows by collecting water and amine while passing through the absorber column; current mitigation techniques are ineffective at capturing the aerosol prior to atmospheric release. This work measures the varying impacts of aerosol nuclei on amine emissions at multiple pilot plants. Aerosol emissions were quantified by the use of Fourier Transform Infrared Spectrometry (FTIR).
MEA emissions were measured in the Slipstream Solvent Test Unit (SSTU) at the National Carbon Capture Center (NCCC). The effect of baghouse pretreatment of the inlet flue gas on the aerosol emissions was observed by FTIR and Phase Doppler Interferometry (PDI); these tests were performed before and after the installation of a pulsed-jet baghouse designed for flue gas mercury control. The baghouse resulted in a ten-fold reduction of amine aerosol emissions, due to the collection of SO3 aerosol nuclei, probably on injected Ca(OH)2. This emissions reduction was due to a decrease in the inlet SO3 content from a max of 9 ppm to 0.5 ppm. FTIR sampling was used to quantify this emissions reduction. PDI analysis confirmed the absence of aerosol at diameters greater than 0.1 μm.
Aerosol generation was performed through the injection of sulfur trioxide into the process inlet at the University of Texas Separations Research Program (UT-SRP) Pilot Plant. SO3 was generated by the oxidation of sulfur dioxide in air over a heated vanadium pentoxide catalyst bed. The 8% SO2/Air mix was fed at flow rates up to 6 liters per minute, and resulted in up to 110 ppm of SO3 at the absorber inlet. The generator converted an average of 94 % SO2 into SO3, with production rates up to 1.7 grams per minute of SO3.
The injected aerosol was allowed to grow within the absorber and water wash. SO3 was found to increase PZ emissions by up to 7.6 mol PZ per mol SO3. Increasing inlet SO3 correlated with increasing PZ emissions.
Keywords: Pilot Plant, Amine Aerosol, Emissions, Fourier Transform Infrared Spectrometry, Phase Doppler Interferometry, Baghouse
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