Experiment Research On Corrosion Resistance Of Alloys In High Temperature Supercritical CO₂ Environment

In recent years,supercritical CO2 Brayton cycle has been a research trend in the energy industry.Supercritical CO2 has good heat transfer and thermodynamic properties,stable chemical properties,and high flow density,the turbine size can be reduced to 1/10 of one in the supercritical water Rankine cycle,and it doesn't require very high temperatures to achieve satisfactary conversion efficiency.Supercritical CO2 becomes a potential plant working medium.The corrosion problem of materials in supercritical CO2 is a key issue.Therefore,it is of great significance to carry out the research on corrosion behavior of materials in supercritical CO2 environment.The dissertation deeply studies the corrosion behaviors of heat resistant steel materials at high temperature CO2 environment on the basis of reference to the existing research results at home and abroad.The material characteristics and oxidation/carbonization corrosion behavior of low alloy steel T22,martensitic steel P92 and austenitic steel Super304H are studied in detail.Based on the supercritical CO2 experimental facility,corrosion tests of T22,P92 and Super304H were carried out by exposure to 550/600?.15MPa environment.We explored the effect of temperature on the growth of oxide film by analyzing the weight gain,oxide surface and cross-section morphology.It is found that the rate of oxidation increases with the temperature.The film is a typical double-layer structure with the iron rich outer layer and the chromium rich inner layer of.The surface of T22 and P92 oxides is porous,and the pore size increases with the temperature.Nodular oxide was formed on the surface of Super304H steel,and the number and size of nodular oxide increased with the temperature and time.Among the three target materials selected,Super304H has the best corrosion resistance in supercritical CO2 environment,which can meet the service needs of 600 degree environment.T22 is the worst after P92,and the latter two materials are not recommended for supercritical CO2 environment above 600 degrees.