Hot Corrosion of Nickel-Base Alloys in Biomass-Derived Fuel Simulated Atmosphere
Biomass fuels are considered to be a promising renewable source of energy. However, impurities present in the fuel may cause corrosion problems with the materials used in the hot sections of gas turbines and only limited data are available so far. As part of the Advanced Turbine Systems Program initiated by the U.S. Department of Energy, the present study provides initial data on the hot corrosion resistance of different nickel-base alloys against sodium sulfate-induced corrosion as a baseline, and against salt compositions simulating biomass-derived fuel deposits. Single crystal nickel-superalloy Rene N5, a cast NiCrAlY alloy, a NiCoCrAlY alloy representing industrially used overlay compositions, and a model {beta}NiAl+Hf alloy were tested in 1h thermal cycles at 950 C with different salt coatings deposited onto the surfaces. Whereas the NiCoCrAlY alloy exhibited reasonable resistance against pure sodium sulfate deposits, the NiCrAiY alloy and Rene N5 were attacked severely. Although considered to be an ideal alumina former in air and oxygen at higher temperatures, {beta}NiAl+Hf also suffered from rapid corrosion attack at 950 C when coated with sodium sulfate. The higher level of potassium present in biomass fuels compared with conventional fuels was addressed by testing a NiCoCrAlY alloy coated with salts of different K/Na atomic ratios. Starting at zero Na, the corrosion rate increased considerably when sodium was added to potassium sulfate. In an intermediate region the corrosion rate was initially insensitive to the K/Na ratio but accelerated when very Na-rich compositions were deposited. The key driver for corrosion of the NiCoCrAlY alloy was sodium sulfate rather than potassium sulfate, and no simple additive or synergistic effect of combining sodium and potassium was found.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Solar Thermal, Biomass Power, and Hydrogen Technologies (EE-13) (US)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 3616
- Report Number(s):
- ORNL/CP-101055; ED 20 01 00 0; ED 20 01 00 0; TRN: AH200112%%495
- Resource Relation:
- Conference: TMS Annual Meeting, San Diego, CA (US), 02/28/1999--03/04/1999; Other Information: PBD: 28 Feb 1999
- Country of Publication:
- United States
- Language:
- English
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