STP531: Operation of Gas Turbines on ASTM 3-GT Fuel

    Hussey, CE
    Senior combustion engineer, Westinghouse Gas Turbine Systems Division, Lester, Pa.

    Lee, SY
    Senior research engineer and manager, Westinghouse Research Laboratories, Pittsburgh, Pa.

    Young, WE
    Senior research engineer and manager, Westinghouse Research Laboratories, Pittsburgh, Pa.

    Pages: 19    Published: Jan 1973


    Abstract

    In 1965 two Westinghouse W171 gas turbines at the Miraflores station of the Panama Canal Co. were overhauled and put into service burning a locally available “Low Vanadium Special Fuel.” The purchase specification was: sodium (less than 10 ppm), vanadium (less than 4 ppm), calcium (less than 10 ppm), and sulfur (less than 1.8 percent). Although some corrosion, even at the reduced turbine inlet temperature of 1375 F was anticipated, it was hoped that the damage would be minimal, thereby justifying the use of this fuel with its definite price advantage. However, after 6375 h of operation, an inspection indicated that corrosion had become extensive.

    In 1966 the turbines were again overhauled and put back in service on the same fuel but in treated state. Periodic sampling and analysis was carried out, and except for one brief excursion, the vanadium averaged 2.5 ppm and the sodium less than 0.5 ppm. After nearly 5000 h of operation, an examination showed only minor corrosion to a completely acceptable extent and the machines have continued to run under these conditions since 1967.

    During this period, extensive laboratory tests were made in a pressurized passage which simulates gas turbine operation to set safe operating limits for the use of various grades of fuel in actual engines. In addition, an attempt was made to obtain quantitative corrosion measurement of the actual turbine blade by means of a device called “dipstick.“ It was shown that with a surface of 1500°F together with a 5 ppm sodium/2 ppm vanadium fuel an excessive amount of attack would occur.

    It may be concluded that in a modern high temperature gas turbine operating under base load conditions the use of a type 3-GT fuel as defined in ASTM Specifications for Gas Turbine Fuel Oils (D 2880-71) will lead to frequent blade and diaphragm replacement. Under some conditions, the turbine will tolerate a fuel with as much as 1 ppm each of sodium and vanadium. Satisfactory operation should result with a fuel as high as 2 ppm in vanadium content if the sodium is lowered by appropriate treatment to less than 0.5 ppm.

    Keywords:

    gas turbines, corrosion, fuels, specifications, heat resistant alloys, sulfidation, vanadium, sodium


    Paper ID: STP36510S

    Committee/Subcommittee: D02.C0

    DOI: 10.1520/STP36510S


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