High Temperature Corrosion Properties of Candidate Materials for 700C Ultra Super Critical Boilers

Achieving higher plant efficiency in thermal power plants is one of the major global challenges from the viewpoint of reducing carbon dioxide emission levels, particularly in coal-fired boilers. In recent times, it has been possible to increase the steam temperature in coal fired ultra supercritical (USC) plants. The target steam temperature of the USC plants is 700C and the key technology is the development of stronger high temperature materials such as newly developed Ni base alloys, Fe-Ni base alloys and austenitic steels, capable of operating under high stresses at increasing high temperatures. Other key demands for those materials are high temperature corrosion resistance for high sulfur coal ash corrosion and steam oxidation in superheater and reheater tubes.In this paper, high temperature corrosion properties and prevention method such as shot blasting and surface coating of these USC candidate materials have been briefly reviewed based on laboratory test results.