Carbon capture with pure monoethanolamine aerosols: Method development for assessing safety hazards and identifying a safe operating window using oxygen-containing flue gas streams

Abstract

Recent research proved the potential of aerosol reactors for post-combustion capture of CO₂ with highly concentrated monoethanolamine (MEA). However, aerosol flammability in a continuous aerosol reactor has not been studied before. Safety cannot be guaranteed when processing oxygen-containing flue gases. The goal of this work is to develop a continuous aerosol safety testing method to investigate aerosol flammability. The proposed method is validated by determining the safe operating window of MEA aerosols by changing parameters on the aerosol and gas side. The relation between aerosol properties and flammability is investigated via high-speed camera. Safe operating conditions in air were found for MEA solutions up to of 70 wt%, suggesting that these solutions are safe to use with any flue gas. However, 80 wt% MEA and higher were flammable. 80 wt% MEA was only flammable at low liquid flow rates. This can be attributed to the increased droplet velocity at higher liquid flow rates, which results in shorter evaporation times. Therefore, the lower flammability limit (LFL) cannot be reached. Overall, MEA concentration and liquid flow rate appear to be the most influential parameters on aerosol flammability. Furthermore, the limiting oxygen concentration (LOC) was investigated. Maximum LOCs were identified as 13.5% and 15% for 100 and 90 wt% MEA, respectively. This information is crucial for matching appropriate flue gases with compatible aerosol reactor configurations. By developing and validating the method for MEA aerosols, this work narrows the gap between aerosol reactors for carbon capture and safely processing oxygen-containing flue gas streams.