Effect of water content on the corrosion behavior of X65 pipeline steel in supercritical CO2-H2O-O-2-H2S-SO2 environment as relevant to CCS application

The water content limit of 1500 ppmv is obtained in supercritical CO2 streams containing 200 ppmv O-2, 200 ppmv SO2 and 200 ppmv H2S at 10 MPa and 50 degrees C. Concurrently, the thermodynamic calculation suggests that impurities change the corrosion process through promoting the water precipitation and changing the water chemistry characteristics. When the water content is below 1500 ppmv, the corrosion effect of impurity interactions dominates the corrosion process of X65 steel. Whereas upon increasing the water content over 1500 ppmv, the corrosion effects from impurity interactions and individual impurity jointly control the corrosion process of X65 steel.