Assessment of material selection for the CO2 absorption process with aqueous MEA solution based on results from corrosion monitoring at Technology Centre Mongstad

In 2017 and 2018, Technology Centre Mongstad (TCM) performed long-term testing of CO2 capture with aqueous monoethanolamine (MEA) solvent through a series of test campaigns. As part of the test campaigns, a selection of materials was assessed for the CO2-MEA process by investigation and analysis of material test coupons. The test coupons were exposed to various operating conditions at five different locations in the plant. Both metal and rubber materials were tested in order to detect possible material compatibility issues with the CO2-MEA process. All metals proved to be suitable, except CS235 which in general showed severe corrosion rates exposed to the MEA solvent. However, a mid-campaign weight loss analysis indicated that CS235 might be acceptable for specific process conditions on the cold rich solvent location. No significant changes were observed on the tested rubber materials, however minor changes in hardness and tensile properties indicated some impact by the MEA solvent environment. In addition to examination of test coupons, the solvent was frequently monitored for typical factors that might indicate or influence corrosion such as the concentration of dissolved metals and heat stable salts (HSS). Some variability in average metal dissolution was observed between specific operational phases, however, the flue gas source did not seem to have significant effect on metal dissolution.