In early 1994 a 100 MW LM6000 combined cycle cogeneration plant will begin operation at New York City’s John F. Kennedy International Airport. Thanks to the extremely high simple cycle efficiency of the LM6000 gas turbine (8200 BTU/KWH, 8650 kJ/KWH-LHV dry) and a sophisticated three-pressure steam generating system, a heat rate below 7000 BTU/KWH-LHV (7380 kJ/KWH-LHV) is expected when operating in combined cycle mode. The dual-spool LM6000 achieves its efficiency by means of a 30:1 compression ratio. 2100 F. (1149 C.) firing temperatures and the direct coupling of the low compressor/turbine rotor to the electric generator. The efficiency of the heat recovery steam generator results from the use of three economizers, three evaporators and two superheaters combined with a patented feedwater heating system which yields a 245 F. (118 C.) exhaust stack temperature.

Operating flexibility is essential in this application. While the dual-fueled plant is designed for pure combined cycle operation, most of the time it will operate in a cogeneration mode — producing up to 250 × 106 BTU/HR (264 × 106 kJ/HR) of steam for heating in the winter and 7000 (24,618 KW) tons of chilling for air conditioning airport terminals in the summer. The waste heat boilers are designed to be supplementary fired on gas fuel when the airport requires the 110 MW maximum capacity of the plant simultaneously with the maximum thermal load of 250 × 106 BTU/HR (264 × 106 kJ/HR).

NOx emissions are controlled with a combination of water injection in the turbine combustors and a dual-function catalyst SCR/CO converter. CO is controlled by means of the converter. Combined gas turbine and duct burner NOx is maintained below 9.0 PPMV dry (@ 15% O2) and CO below 1.5 PPH (0.68 KG/HR) dry (@ 15% O2) when operating on gas fuel.

Cycle details, equipment selection and operation as well as the plant economics provide a useful insight into the benefits of these recent developments in gas turbine and heat recovery combined cycle cogeneration technology.

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