Abstract
The U.S. Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) are co-sponsoring a multi-year project managed by Energy Industries of Ohio (EIO) to evaluate materials for ultra-supercritical (USC) coal-fired boilers. USC technology improves cycle efficiency and reduces CO2 and pollutant emissions. With turbine throttle steam conditions reaching 732°C (1350°F) at 35 MPa (5000 psi), current boiler materials, which operate below 600°C (1112°F), lack the necessary high-temperature strength and corrosion resistance. This study focuses on the fireside corrosion resistance of candidate materials through field testing. Evaluated materials include ferritic steels (SAVE12, P92, HCM12A), austenitic stainless steels (Super304H, 347HFG, HR3C), and high-nickel alloys (Haynes 230, CCA617, Inconel 740, HR6W), along with protective coatings (weld overlays, diffusion coatings, laser claddings). Prior laboratory tests assessed corrosion under synthesized coal-ash and flue gas conditions for three North American coal types (Eastern bituminous, Midwestern high-sulfur bituminous, and Western sub-bituminous), with temperatures ranging from 455°C (850°F) to 870°C (1600°F). Promising materials were installed on retractable corrosion probes in three utility boilers burning different coal types. The probes maintained metal temperatures between 650°C (1200°F) and 870°C (1600°F). This paper presents new fireside corrosion probe results after approximately one year of exposure for Midwestern and Western coal types.
