Abstract
Both indirect- and direct-fired supercritical CO2 (sCO2) cycles for high efficiency power generation are expected to have impurities that may greatly alter the compatibility of structural alloys in these environments. However, the laboratory data on this subject are limited and inconclusive. For indirect applications, comparison 500-h cycles were conducted at 750°C at 1 and 300 bar with research grade and industrial-grade (higher possible impurities) CO2. The mass change results suggest only limited differences between these conditions for exposures up to 5,000 h. For direct-fired or open cycles, a test rig is being assembled to conduct similar exposures at 750°C/300 bar in CO2+1%O2-0.25%H2O. Commercial Fe- and Ni-base structural alloys were exposed in each environment and reaction products have been characterized after 1,000, 2,500 and 5,000 h exposures.
