Development and Validation of Advanced Oxidation Protective Coatings for Super Critical Steam Power Generation Plants

Abstract

Increasing the efficiency of coal-fired power plant by increasing steam temperatures and pressures brings benefits in terms of cheaper electricity and reduced emissions, particularly CO 2 . In recent years the development of advanced 9%Cr ferritic steels with improved creep strength has enabled power plant operation at temperatures up to 600 -620ºC such that these materials are currently being exploited to construct a new generation of advanced coal-fired plant. However, the move to higher temperatures and pressures creates an extremely hostile oxidising and errosive environment. To enable the full potential of the advanced 9%Cr steels to be achieved, it is vital that protective coatings are developed, validated under high pressure steam environments and applied successfully to candidate components from the high pressure steam path. This paper reviews recent work conducted within the Framework V Brite EuRam project "Coatings for Supercritical Steam Cycles" (SUPERCOAT) to develop and demonstrate advanced slurry and thermal spray coating technologies capable of providing steam oxidation protection at temperatures in excess of 620°C and up to 300 bar pressure. The programe of work described has demonstrated the feasibility of applying a number of candidate coatings to steam turbine power plant components and has generated long-term steam oxidation rate and failure data that underpin the design and application processing work packages needed to develop and establish this technology for future and retrofit plant.