Fireside and steamside performance in biomass power plant

To address the challenge of climate change, the energy sector is developing novel strategies to reduce greenhouse gas emissions. One route is to increase steam temperatures and pressures (above 650°C and 350 bar). Another route is the use of potential net zero emissions fuels, like biomass. Both these routes cause issues for the heat-exchanger materials due to the differences in composition of the combustion environments generated, compared to coal.

This paper characterises candidate superheater/reheater alloys’ behaviour (Sanicro 25 and IN740) at 700°C. 1,000 h fireside and 10,000 h steamside exposures were carried out, the first using ‘deposit recoat’ techniques. Sample cross-sections were analysed using dimensional metrology and SEM/EDX. Fireside results for Sanicro 25 showed degradation throughout the samples’ thicknesses. In steamside exposures, Sanicro 25 formed a Cr-rich scale, and Nb rich particles (z-phase). IN740 showed lower metal and sound metal damage than Sanicro 25 for fireside and steam oxidation exposures.