Power plants – Combustion products used as motive fluid – Multiple fluid-operated motors
Reexamination Certificate
2001-04-17
2003-07-08
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
Multiple fluid-operated motors
C060S806000
Reexamination Certificate
active
06588197
ABSTRACT:
The entire disclosures of Japanese Patent Application Nos. 2000-116337 filed on Apr. 18, 2000 and 2001-61327 filed on Mar. 6, 2001, including specifications, claims, drawings and summaries are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a steam control apparatus for a turbine which introduces steam from a waste heat recovery boiler, or fluid from an auxiliary passage, to a blade ring of a gas turbine and a high-temperature component, such as a combustor, to thereby effect temperature control.
2. Description of the Related Art
From the viewpoint of economy and effective use of energy resources, various measures for improving efficiency have been implemented in power generation facilities (power generation plants). One measure is employment of a turbine power generation plant (a combined cycle power generation plant) in which a gas turbine and a steam turbine are combined. In a combined cycle power generation plant, high-temperature exhaust gas from a gas turbine is fed to a waste heat recovery boiler, in which steam is generated via a superheating unit, and the thus-generated steam is fed to a steam turbine, in which the generated steam performs work.
High-temperature components, such as a combustor, of a gas turbine has been cooled by means of air. However, in order to cope with a recent increase in combustion temperature, cooling by means of steam has come into use. In relation to a combined cycle power generation plant as well, there is a plan to use a steam turbine in combination with a gas turbine in which high-temperature components such as a combustor are cooled by means of steam, to thereby obtain a highly efficient power generation plant. Moreover, in order to cope with a recent increase in operation temperature of a gas turbine, various studies have been performed on a technique for introducing steam to the blade ring portion of the turbine so as to optimally control the clearance between the blade ring portion and moving blades. That is, there is a plan to effect temperature control by means of steam in order to prevent contact between the moving blades and the blade ring portion at the time of startup and to maintain a minimum clearance between the moving blades and the blade ring portion during ordinary operation, to thereby achieve safety and high efficiency simultaneously.
In relation to a combined cycle power generation plant, various studies have been performed on a technique for introducing steam to the blade ring portion of the turbine so as to optimally control the clearance between the blade ring portion and moving blades and for cooling high-temperature components such as a combustor by means of steam.
Control of the clearance between the moving blades and the blade ring portion must be performed differently from cooling of high-temperature components such as a combustor by means of steam. Specifically, the clearance control must be performed such that at the time of startup, the clearance is made relatively large through introduction of steam of relatively high temperature, and during ordinary operation, the clearance is made relatively small through introduction of steam of relatively low temperature. In contrast, cooling of high-temperature components must be performed through introduction of steam of low temperature. As described above, when control of the clearance between the moving blades and the blade ring portion by means of steam and cooling of high-temperature components, such as a combustor, by means of steam are performed, steam must be introduced while the flow rate of steam, etc. are controlled in order to simultaneously satisfy a temperature requirement in clearance control and a temperature requirement in cooling. However, in the existing combined cycle power generation plant, a satisfactory technique for steam control which satisfies the two different requirements regarding temperature has not been established.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a steam control apparatus for a turbine which can achieve control of the clearance of a blade ring portion by means of steam and cooling of high-temperature components such as a combustor by means of steam.
In order to achieve the above object, the present invention provides a steam control apparatus for a turbine, comprising a waste heat recovery boiler including a high-pressure unit for generating high-pressure steam by use of exhaust gas of the gas turbine, and a low-pressure unit for generating low-pressure steam by use of exhaust gas of the gas turbine. A steam turbine is operated by means of steam generated by the waste heat recovery boiler. A low-pressure-side steam introduction passage introduces low-pressure steam from the low-pressure unit of the waste heat recovery boiler to the steam turbine. A high-pressure-side steam introduction passage introduces high-pressure steam from the high-pressure unit of the waste heat recovery boiler to the steam turbine. A steam passage branches off the low-pressure-side steam introduction passage and serves as a bypass for introducing low-pressure steam from the low-pressure unit to a blade ring of the gas turbine and a high-temperature component. A high-pressure steam passage branches off the high-pressure-side steam introduction passage and merges into the steam passage on the upstream side of the blade ring of the gas turbine and the high-temperature component. A flow-rate adjustment-control unit adjusts the flow rate of steam flowing through the steam passage and the flow rate of steam flowing through the high-pressure steam passage to thereby adjust the flow rate and temperature of steam flowing through the blade ring of the gas turbine and the high-temperature component. In the steam control apparatus of the present invention, since the temperature and flow rate of steam introduced to the turbine and the high-temperature component can be controlled properly through mixing high-pressure steam and intermediate-pressure steam, two different requirements, i.e. adjustment of steam temperature and securing of a sufficient steam flow rate, can be satisfied simultaneously. As a result, it becomes possible to simultaneously achieve control of the clearance of the blade ring by means of steam and cooling of the high-temperature component by means of steam.
Preferably, the flow-rate adjustment-control unit comprises a first flow control valve provided in the low-pressure-side steam introduction passage on the downstream side of the branching portion of the steam passage and adapted to control the flow rate of steam flowing through the steam passage through adjustment of the flow rate of steam flowing through the steam turbine. A second flow control valve is provided in the high-pressure steam passage and adapted to control the temperature of steam flowing through the steam passage through adjustment of the flow rate of high-pressure steam. A temperature detector detects the temperature of steam flowing thorough the steam passage on the downstream side of the merging portion of the high-pressure steam passage. A pressure detector detects the pressure of steam flowing through the steam passage on the downstream side of the merging portion of the high-pressure steam passage. A control unit controls the first and second flow control valves on the basis of the temperature detected by the temperature detector and the pressure detected by the pressure detector in order to maintain, at predetermined values, the flow rate and temperature of steam flowing through the blade ring of the gas turbine and the high-temperature component.
In this case, two different requirements, i.e., adjustment of steam temperature and securing of a sufficient steam flow rate, can be satisfied simultaneously without use of expensive detection means or valve members.
Preferably, the high-temperature component is a combustor. The pressure detector is a differential-pressure detector for detecting a difference in steam pressure betwee
Higashi Kazuya
Hiramoto Koji
Nagata Shouichi
Tanaka Tomoka
Casaregola Louis J.
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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