The 700°C-class advanced ultra-supercritical (A-USC) boiler is a promising technology for
high-efficiency coal-fired thermal power generation. To realize such boilers, it is critical to
develop and validate the creep enhanced Ni-based alloys and advanced ferritic steels, both of
which can withstand temperatures substantially higher than conventional boilers. In addition to the
long-term creep rupture strength and manufacturing techniques, the steam oxidation properties
and the coal ash-induced high-temperature corrosion properties were evaluated. The results
indicate that the test materials have sufficient strength and corrosion resistance and the pressure
parts can be manufactured without problems. The heat transfer tube panels and pipes were
additionally installed on existing boilers in May 2015. Since then, the demonstration operation has
been continued in a simulated A-USC boiler environment. We will also develop technologies for
creep damage assessment and non-destructive inspection for maintenance purposes, aiming for the
early commercialization of A-USC boilers.
