Design of Supercritical CO2 Corrosion Experimental Device and Research on Multiphase Corrosion Simulation Evaluation

This research designed an experimental apparatus and method that integrates multiphase simulation, parameter control, and real-time monitoring to address the challenge of in-situ corrosion simulation evaluation caused by CO2 multiphase coupling in CCUS technology implementation. This device integrates visualization of high-temperature and high-pressure reactors, supercritical fluid chromatography analysis units, and automatic potentiometric titration technology to achieve in-situ simulation and precise control of the dynamic evolution process of CO2 phase and corrosive media. The corrosion behavior of N80 and J55 carbon steel under different pressure (6–10 MPa) and temperature conditions was systematically investigated. Combined with weight loss analysis, SEM, XRD and other characterization methods, the influence of phase changes on corrosion morphology, rate and product evolution was revealed. Experiments have shown that under supercritical conditions (P ≥ 7.3 MPa), the uniform corrosion rates of the two types of steel are significantly higher than those in non-critical states. Among them, the rich CO2 phase is locally corroded due to high mineralization water condensation, and the maximum pitting depth of N80 steel exceeds 100 μm at 10 MPa; The corrosion products of the rich H2O phase transform from FeCO3 to a composite film of CaCO3·CaMg(CO3)2 with increasing pressure. At 10 MPa, the uniform corrosion rates of J55 and N80 steels are 1.071 mm/a and 1.166 mm/a, respectively. The composite film inhibits corrosion by hindering the diffusion of the medium. The multiphase corrosion simulation platform constructed in this study provides a scientific basis for the evaluation of pipe corrosion and anti-corrosion design, which is highly in line with the strategic needs of CCUS industry development.