Abstract
Material selection for waterwall and superheater/reheater tubing for a heavy liquid fuel-fired supercritical boiler was performed based on hot corrosion testing. This was carried out at varying temperatures through simulated firing conditions using heavy liquid fuel on bare carbon steel UNS K02599, low-alloyed steel UNS K11562, carbon steel with UNS N06022 weld overlay, and carbon steel with 50Cr-50Ni thermal spray coating for waterwall tubing; and on austenitic stainless steels UNS S34709, UNS S30432, UNS S31042, Ni-based alloys UNS N06617, Alloy 740, Ni-Cr-Fe alloys UNS S35045 and UNS N08810 for superheater/reheater tubing. Mg-based fuel additive, an inhibitor of hot corrosion, was also used in testing the superheater/reheater tubing. The results showed that carbon steel with UNS N06022 overlay and austenitic stainless steel UNS S31042 yielded the best performance for waterwall tubing and superheater/reheater tubing, respectively. The application of a Mg-based fuel additive also showed great merit in suppressing corrosion in the superheater and reheater sections. This test program constitutes part of a feasibility study for the design and construction of supercritical boilers to enhance power generation in the Kingdom.
