Fuel System Contaminants Bring Arizona Station Offline

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Researched by Industrial Info Resources (Sugar Land, Texas)--Since September 20, employees at Harquahala Generating Station (Tonopah, Arizona) have known that the plant's natural gas lines weren’t delivering the fuel efficiently to their combustion turbine units, and now they know why.

Apparently, more than 100 gallons of oil have already been drained from the natural gas lines, and there’s still more to remove. Plant personnel said that it was pooling in the low spots throughout the system and that it also ended up blowing out a bunch of fuel filters whose debris also has to be removed. To aid in expediting the outage, temporary bypass lines were constructed so that a cleaning company could chemically clean the system without fear of leaking fuel, and the inherent dangers that come with dealing with pressurized natural gas. They are hoping to have the issue resolved by this weekend, but with such a severe oil leak compromising the delivery of clean fuel to the turbines, tests will have to be conducted to ensure that no oil contaminates or particulate matter clog the fuel system.

Commissioned in 2003, the plant is owned by Harquahala Generating Company LLC (Bethesda, Maryland) and operated by North American Energy Services (Issaquah, Washington). The plant was designed to utilize water resources from either the Colorado River (via the Central Arizona Project (CAP) aqueduct) or from local ground-water sources. Interestingly, Harquahala generates high-quality water for re-use by the power plant, as well as processing their remaining solid waste based on the chemistry of feed-water to the plant. Zero Liquid Discharge regulations mandate that the resulting solid waste (in the form of wetcake) is to be generated with a nominal content of 10% moisture for proper landfill disposal.

Harquahala consists of three combined-cycle power blocks, each with a 240-megawatt natural gas fired Siemens Westinghouse Power Corporation W501G combustion turbine generator equipped with steam injection and evaporative cooling for power augmentation, a Vogt-NEM heat recovery steam generator (HRSG) equipped with selective catalytic reduction (SCR) to reduce NOx emissions, and a 121-megawatt (MW) Siemens Westinghouse Power Corporation (reheat condensing) steam turbine generator. In total, the power station is capable of delivering more than 1,080 (MW) of electricity to the desert southwest, including the cities of Phoenix, Tucson and Las Vegas.

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