Superheater Materials Testing for USC Boilers: Steam Side Oxidation Rate of 9 Advanced Materials in Industrial Conditions

Three identical experimental superheaters were built and operated in the superheater zone of a recent supercritical unit of the Vestkraft Power Plant. The first one was dismantled after one-year service exposure (7,720 hours) and the second after three years (22,985 hours). The last one is still running and will be dismantled in 2002, after 7 years service exposure (approximately 50,000 hours). The operating conditions were representative of a superheater in a future ultra-supercritical (USC) boiler. During the operation of the superheater project, the operator fully documented the various parameters, thus enabling the material behaviours to be understood. As the major outcome of the project, it was found that the internal steam oxidation damage after 23,000 hours was much greater than expected for martensitic steels and lower than expected for austenitic steels.