Amine Aerosol Characterization by Phase Doppler Interferometry

Preventing emission of gaseous and aerosol pollutants is a crucial function of CO2 capture systems using aqueous amine solvents. Aerosols, not volatility or entrainment, constitute the largest source of amine loss. This effort presents a means of understanding the dynamics of high-density aerosol fields in gas-liquid contacting devices by developing an in situ particle analysis technique called Phase Doppler Interferometry (PDI). Particle size distributions (PSDs) and total particle densities were measured and compared directly to hot-gas Fourier Transform Infrared Spectroscopy (FTIR) on bench- and pilot-scale apparatuses for two amine systems: piperazine (PZ) and monoethanolamine (MEA). A post-processing algorithm integrated PSDs (between 0.1 to 12 μm) and used the total particle density (up to 107 part./cm3) to calculate the total mass of aerosol liquid per unit volume of gas (total phase concentration). Assuming a constant amine concentration in the aerosol liquid by sampling day, the integrated PDI data matched FTIR measurements within 40%. Unit operation changes are clearly visible in the average aerosol diameter and total density. The total particle density and the average diameter were found to be inversely related in pilot plant sampling; the condensable mass is constant in the gas phase.