Use of Carbon Steel for Construction of Post-combustion CO₂ Capture Facilities: A Pilot-Scale Corrosion Study

Corrosion studies were carried out on metal coated and noncoated carbon steel as well as stainless steel in a pilot-scale post-combustion CO₂ capture process. Aqueous 30 wt % monoethanolamine (MEA) solvent was used without any chemical additive for antioxidation to examine a worst-case scenario where corrosion is not mitigated. The corrosion rate of all carbon steels was almost zero in the absorber column and CO₂ lean amine piping except for Ni-coated carbon steel (<1.8 mm/yr). Ni₂Al₃/Al₂O₃ precoated carbon steels showed initial protection but lost their integrity in the stripping column and CO₂ rich amine piping, and severe corrosion was eventually observed for all carbon steels at these two locations. Stainless steel was found to be stable and corrosion resistant in all of the sampling locations throughout the experiment. This study provides an initial framework for the use of carbon steel as a potential construction material for process units with relatively mild operating conditions (temperature less than 80°C), such as the absorber and CO₂ lean amine piping of a post-combustion CO₂ capture process. It also warrants further investigation of using carbon steel with more effective corrosion mitigation strategies for process units where harsh environments are expected (such as temperatures greater than 100°C). (Figure Presented).