Supercritical oxidation of boiler tube materials

The advantage of using supercritical water (SCW) systems for power generation is based on the increased thermodynamic efficiency when operating at higher temperature and pressure. This has been realised for many years in medium to large size supercritical fossil plants. High efficiency in power generation is not only desirable because of economical reasons but also for enhanced environmental performance meaning reduced quantity of forming ash and emitted pollutants including CO2. Steam oxidation has become an important issue for steam power plants as operating temperatures increase from current to 650°C and even higher. To achieve these higher steam values new materials are needed. This paper presents results of the oxidation performance of potential new alloys (FeCrAlY, NiCrAl and Sanicro 25) in a supercritical water autoclave environment at 650°C/250 bar, with 150 ppb dissolved oxygen