Power plants – Combustion products used as motive fluid – With combustible gas generator
Reexamination Certificate
1999-04-02
2001-07-17
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
With combustible gas generator
C060S039182, C060S039520
Reexamination Certificate
active
06260348
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combined cycle power plant using fossil fuel including methanol and the like.
2. Description of the Prior Art
FIG. 28
is a diagrammatic view of a prior art combined cycle power plant, using pure oxygen as oxidizing agent and methane as fuel, which has been disclosed from the Graz Institute of Technology. In the figure, numeral
1
designates a compressor, which compresses a mixture gas of steam and carbon dioxide as working fluid to a pressure decided by an entire system optimization study. Numeral
2
designates a combustor, which is supplied with oxygen needed for an equivalent combustion of the methane as fuel to generate a high temperature high pressure combustion gas, wherein components of the combustion gas are carbon dioxide and steam. Numeral
3
designates a high temperature gas turbine, which expands the high temperature high pressure combustion gas to obtain a work. Numerals
4
,
5
designate first and second heat exchangers, respectively, and a condensed water produced at a bottoming system from an exhaust gas of the high temperature gas turbine
3
extracted at a midpoint between the first and second heat exchangers
4
,
5
is heated at the first and second heat exchangers
4
,
5
to generate a high temperature high pressure steam. Numeral
6
designates a high pressure steam turbine, which expands the high temperature high pressure steam generated at the first and second heat exchangers
4
,
5
approximately to an inlet pressure of the combustor
2
to obtain a work as well as to send the steam so expanded to be mixed into an inlet of the combustor
2
. Remaining exhaust steam from the high temperature gas turbine
3
which has passed through the first and second heat exchangers
4
,
5
with its temperature having been reduced returns to an inlet of the compressor
1
.
Numeral
7
designates a low pressure turbine, which expands the combustion gas extracted at the midpoint between the first and second heat exchangers
4
,
5
approximately to a vacuum to obtain a work. Numeral
8
designates a carbon dioxide compressor (vacuum pump), which compresses the mixture gas the containing the entire amount of the carbon dioxide generated at the combustor
2
approximately to the atmospheric pressure to thereby discharge the carbon dioxide as a combustion-generated product outside of the system. Numeral
9
designates a condenser, in which an outlet gas of the low pressure turbine
7
which has been pressure-reduced by the carbon dioxide compressor (vacuum pump)
8
is heat-exchanged by the sea water or the like to be temperature-reduced so that the steam is liquefied. The liquefied water is pressurized by a pressure pump
10
to be fed into the first and second heat exchangers
4
,
5
to thereby become the high temperature high pressure steam. The steam as the combustion-generated product which has been expanded at the low pressure turbine
7
is mostly liquefied to water at the condenser
9
, and a remaining portion thereof becomes a drain in the process of being compressed by the vacuum pump
8
approximately to the atmospheric pressure to be discharged outside of the system.
In the prior art combined cycle power plant as mentioned above, while the high temperature combustion gas having the component of carbon dioxide and steam is obtained using the methane as fuel and oxygen, it is also possible to use a methanol (CH
3
OH) fuel or other fossil fuels, but in this case, it has been a problem that the gross thermal efficiency is low.
SUMMARY OF THE INVENTION
In view of the problem in the prior art, therefore, it is an object of the present invention to improve the prior art combined cycle power plant using the methane fuel so that a turbine plant using methanol fuel or other fossil fuels is obtained, gross thermal efficiency thereof is more enhanced than that of the prior art combined cycle power plant and reliability of the turbine plant is also enhanced.
In order to attain said object, the present invention provides the following aspects (1) to (27):
(1) A turbine plant comprising a compressor for compressing a mixture gas of steam and carbon dioxide as a working fluid; a combustor for burning a fuel together with the working fluid from the compressor added with oxygen; a high temperature turbine for expanding a combustion gas from the combustor to obtain a work; a bottoming system for driving a low pressure turbine by an exhaust gas from the high temperature turbine to obtain a work; a heat exchanger for heating a condensed water from the bottoming system to a high temperature steam by a heat exchange with the exhaust gas from the high temperature turbine and for leading the exhaust gas (after it is used for the heat exchange) into an inlet of the compressor as the working fluid; and a high pressure turbine for expanding the high temperature steam of the bottoming system heated at the heat exchanger to obtain a work and for mixing the steam so expanded into the combustor. In addition, a reformer is provided for receiving a mixture of methanol and water to be reformed into hydrogen and carbon dioxide by heat absorbed at the heat exchanger and for supplying the hydrogen and carbon dioxide into the combustor as a fuel; and a high temperature turbine cooling system is provided for extracting the working fluid from an outlet of the compressor and an outlet of the high pressure turbine to be led into a high temperature portion of the high temperature turbine for cooling thereof as a cooling medium.
In the invention of aspect (1), the reformer can reform the mixture of methanol (CH
3
OH) and water (H
2
O) into hydrogen (H
2
) and carbon dioxide (CO
2
) so that the gross thermal efficiency is enhanced. Further, the high temperature portion of the high temperature turbine can be cooled by the high temperature turbine cooling system so that reliability of the high temperature turbine is enhanced.
(2) A turbine plant as mentioned in aspect (1) above, characterized in that the compressor comprises a low pressure compressor and a high pressure compressor. Between the low pressure compressor and the high pressure compressor, a passage is provided for flowing therethrough the working fluid via an intercooler. A portion of the condensed water from the bottoming system is mixed into the intercooler under pressure.
In the invention of aspect (2), in addition to the effect of the invention of aspect (1), the low pressure compressor outlet gas is temperature-reduced so that the compression power of the high pressure compressor is reduced so that the gross thermal efficiency is enhanced. Also, the high pressure compressor outlet temperature is reduced so that thereby reliability of the disc strength of the high pressure compressor outlet portion is enhanced. Further, the combustor inlet gas temperature is reduced so that reliability of the high temperature portion of the combustor is also enhanced.
(3) A turbine plant as mentioned in aspect (1) above, characterized in that there is provided between the outlet of the compressor and an inlet of the combustor a regenerative heat exchanger for elevating a combustor inlet gas temperature by a heat exchange between an outlet gas of the compressor and the exhaust gas from the high temperature turbine.
In the invention of aspect (3), in addition to the effect of the invention of aspect (1), there is provided the regenerative heat exchanger so that the combustor inlet gas temperature is elevated, the fuel flow rate is reduced and the gross thermal efficiency is enhanced.
(4) A turbine plant as mentioned in aspect (3) above, characterized in that the compressor comprises a low pressure compressor and a high pressure compressor. Between the low pressure compressor and the high pressure compressor, a passage is provided for flowing therethrough the working fluid via an intercooler, and a portion of the condensed water from the bottoming system is mixed into the intercooler under pressure.
In the invention of aspect (4), in addition to the effect of the in
Fukue Ichiro
Mori Hidetaka
Sugishita Hideaki
Uematsu Kazuo
Casaregola Louis J.
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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