| Abstract Scope |
Supercritical CO2 (sCO2) power cycles, particularly direct-fired cycles, have the possibility of revolutionizing clean fossil energy. To maximize efficiency, the peak temperatures are expected to be above 700°C and, therefore, require the use of wrought superalloys for structural components. For the highest temperature applications >750°C, precipitation strengthened alloys such as 740 and 282 have been shown to have good compatibility in sCO2 without impurities (i.e. indirect cycles). At temperatures <650°C, it would be desirable to use less expensive alloys, however, steels are known to be susceptible to carburization, especially with O2 and H2O impurities in 300 bar sCO2. Laboratory autoclave results with and without O2 and H2O impurities typical of direct-fired cycles are being collected on a range of alloys including less expensive Ni-based alloys like 825 and 120 and advanced austenitic steels like 709. Their relative performance is being compared after 1-2 kh exposures at 600°-800°C and reaction products are being characterized using a variety of characterization techniques to study the reaction products and quantify the C content. Research sponsored by the U.S. Department of Energy, Office of Fossil Energy and Carbon Management. |