A mechanistic model for pipeline steel corrosion in supercritical CO2–SO2–O2–H2O environments

A mechanistic model was established to predict uniform corrosion rate and investigate the corrosion mechanisms of pipeline steel in supercritical CO2–SO2–O2–H2O environments. A six-region division (SIWDES: Supercritical CO2, Interface, Water film, Deposition, Electrodic, and Solid) was applied to mathematically describe the model. The modified three-characteristic-parameter correlation model was used to calculate the ion activity coefficients, which calculates the activity coefficients of ions in thin water film with high ionic strength. The model can reasonably predict the corrosion rate of pipeline steel for the primary variables, determine the concentration distribution of each component in the water and product films, and also reflect the impact of corrosion product film on corrosion rate. A comparative analysis between the model and the experimental results showed that the model reasonably predicted the effects of the main factors on corrosion rate.