Modeling aerosols in amine-based CO2 capture

Controlling emission of gaseous and aerosolized pollutants is a critical function of CO2 capture systems using aqueous amine solvents. Absorption of species into aerosols suspended within flue gas, not mechanical entrainment, has been identified as a dominant volatile discharge route. This work investigated the effects of operating conditions on aerosol growth in a combined, PZ-based, absorber/water wash column through simulation using thermodynamic, kinetic, and transport models in Aspen Plus (R) in combination with an external aerosol model in MATLAB (R). Aerosol transport equations included continuum-kinetic length-scale corrections. In the absorber, aerosols grow by continual uptake of CO2 and PZ. Subsequently, H2O condenses to return to saturation. Droplets grow faster in non-intercooled columns because the temperature bulge and leaner solvent increases available PZ in the bulk gas phase. Aerosols grow fastest where the solvent is lean and hot, i.e., above the temperature bulge. Droplets grow faster in the water wash because of elevated PH2O relative to that in the absorber. PH2O is proportional to the amine concentration in the wash loop. The growth mechanism in the water wash can be exploited to remove aerosols by increasing residence time or diluting the wash solution. Increasing aerosol size increases removal efficiency while minimizing the Delta P characteristic to particle collectors. (C) 2013 The Authors. Published by Elsevier Ltd. Open access under CC BY-NC-ND license. Selection and/or peer-review under responsibility of GHGT