Power plants – Combustion products used as motive fluid
Reexamination Certificate
1998-11-02
2001-03-13
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S734000
Reexamination Certificate
active
06199366
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a gas turbine and, more particularly, to a gas turbine provided with a means for controlling a quantity of compressed air supplied from a compressor to a combustor of the gas turbine.
In recent years, as fuel supplied to a combustor of a gas turbine and burned, various fuels such as a gas generated in a coal gasification furnace, a gas (byproduct gas) generated in a blast furnace or a coke oven, etc. are used. However, such gases each have a property that a calorific value is lower than a usual fuel. JP A
60-222531
discloses that a fuel air ratio is controlled to be proper by providing an air compressor and fuel compressor provided with multi-stage variable vanes and controlling the multi-stage variable vanes according to a calorific value of a fuel to be burnt in the combustor.
However, in the above-mentioned apparatus, a construction of the compressor itself is been made complicated. Further, a usual fuel such as LNG has a calorific value of about 10,000 kcal/kg, while a calorific value of a byproduct gas from a blast furnace, etc. is about 1,000 kcal/kg which is low and about {fraction (1/10)} of that of the usual fuel. For generating a high temperature high pressure gas by combustion of a fuel gas of low calorific value in the same manner as when a usual fuel is supplied, it is necessary to inject the fuel gas at a larger flow rate (about 10 times in this case) than the usual fuel flow rate according to the calorific value of the fuel gas. When a large amount of combustion gas flows into the turbine in this manner, a discharge pressure of the compressor rises and a margin for surging of the compressor decreases. On the contrary, when a compressor of smaller air capacity than a gas turbine compressor used for a usual fuel is used to make a discharge pressure constant so that a quantity of combustion gas flowed into the turbine becomes the same as that in the turbine used for a usual fuel, such requirement can not be satisfied by only one such compressor in a case where a plurality of fuel gases different in calorific value are supplied to the combustor.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a gas turbine which is able to effect a stable operation even in a case where fuels different in calorific value are supplied into a combustor.
The present invention relates to a gas turbine comprising a compressor, a combustor for burning compressed air discharged from the compressor and fuels different in calorific value supplied there to and a turbine connected to the compressor through a shaft and driven by combustion gas supplied from the combustor, wherein the gas turbine further comprises an extraction out of the system for extracting a part of the compressed air supplied from the compressor to the combustor, and a control means for controlling, so as to suppress a pressure change of the compressed air supplied into the combustor, by changing a quantity of compressed air extracted from the extraction system out of the system according to usage of fuels different in calorific value.
Thereby, even if fuels different in calorific value are supplied, the gas turbine can be stably and easily controlled.
REFERENCES:
patent: 3659417 (1972-05-01), Grieb
patent: 4258544 (1981-03-01), Gebhart et al.
patent: 4607486 (1986-08-01), Cole
patent: 4959954 (1990-10-01), Nishijima
patent: 5694768 (1997-12-01), Johnson et al.
patent: 60-222531 (1985-11-01), None
patent: 61-255225 (1986-11-01), None
Hoizumi Shinichi
Murata Hidetaro
Takehara Isao
Teranishi Mitsuo
Wada Katsuo
Freay Charles G.
Gartenberg Ehud
Hitachi , Ltd.
Mattingly, Stanger & Malur
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