Corrosion and Bulk Phase Reactions in CO2 Transport Pipelines with Impurities: Review Of Recent Published Studies

AbstractA limited number of papers report experimental corrosion data in the presence of flue gas impurities like SOx, NOx and O2. When SO2, water and O2 are present, sulphurous and/or sulphuric acid (H2SO3 and H2SO4) might form. The minimum water concentration required for acid formation is not known, but the presence of FeSO3 and/or FeSO4 on the corroded surface in some experiments indicate that the reactions occur at water concentrations far below the water solubility in pure CO2-water systems.The corrosiveness increases considerably when NOx is present. NO2 is highly soluble in water and reacts with water to produce nitric acid and NO under atmospheric conditions. The same type of reaction probably occurs in the dense phase CO2 system. Experimental results indicate that the rust-like dusty products formed does not efficiently reduce the corrosion rate.There is limited number of papers presenting data and discussing the effect of combined impurities on corrosion. When both, NO2 and SO2 are present, NO2 catalyzes the oxidation of SO2 to form sulphuric acid. In addition, in the presence of H2S, elemental sulphur can form.Such interactions between impurities are especially dangerous when network pipeline systems are considered and CO2 streams from different sources and with different impurities are mixed. As a result two non-corrosive streams can become very corrosive if highly corrosive acids are formed as a result of the reaction between added impurities