GAS TURBINE PLANT AND METHOD OF IMPROVING EXISTING GAS TURBINE PLANT

A gas turbine plant comprises: a gas turbine having a compressor configured to compress air, a combustor configured to mix compressed air compressed by the compressor with fuel to generate combustion gas, a turbine connected to the compressor and configured to acquire rotary power by the combustion gas, and an air bleeding piping configured to supply the compressed air bled off from the compressor to the turbine as cooling air; and an auxiliary compressed air supply apparatus having a separately placed compressor different from the compressor, a motor configured to rotate the separately placed compressor, and an auxiliary compressed air piping configured to connect the separately placed compressor to the air bleeding piping to supply auxiliary compressed air compressed by the separately placed compressor to the air bleeding piping. The gas turbine further includes a cooling apparatus connected to the air bleeding piping and configured to cool down the cooling air.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2015-181928 filed in Japan on Sep. 15, 2015.

FIELD

The present application relates to a gas turbine plant, and a method of improving an existing gas turbine plant.

BACKGROUND

Conventionally, a gas turbine plant has a compressor, a combustor, and a turbine, and generates combustion gas by causing the combustor, to which fuel is supplied, to combust air compressed by the compressor. By supplying the generated combustion gas to the turbine and rotating the turbine, thermal energy is converted into rotational energy.

In Japanese National Publication of International Patent Application No. 2002-519580, a configuration is described, in which a compressor that is separately placed from a compressor connected to a turbine of a gas turbine plant is provided, and which supplies air compressed by the separately placed compressor to the gas turbine plant.

By providing a separately placed compressor like in the apparatus described in the Patent Literature above to increase flow rate of supplied air, even in an environment where temperature of outside air is high and air having low air density is drawn in, reduced output of the gas turbine plant is able to be increased. However, in the apparatus described in the Patent Literature above, increase in load applied to the gas turbine by the compressed air supplied from the separately placed compressor may become larger.

SUMMARY

It is an object of the present disclosure to at least partially solve the problems in the conventional technology.

In one aspect, there is provided a gas turbine plant, comprising a gas turbine having a compressor configured to compress air, a combustor configured to mix compressed air compressed by the compressor with fuel to generate combustion gas, a turbine connected to the compressor and configured to acquire rotary power by the combustion gas, and an air bleeding piping configured to supply the compressed air bled off from the compressor to the turbine as cooling air, and an auxiliary compressed air supply apparatus having a separately placed compressor different from the compressor, a motor configured to rotate the separately placed compressor, and an auxiliary compressed air piping configured to connect the separately placed compressor to the air bleeding piping to supply auxiliary compressed air compressed by the separately placed compressor to the air bleeding piping, wherein the gas turbine includes a cooling apparatus connected to the air bleeding piping and configured to cool down the cooling air.

In one aspect, there is provided a method of improving an existing gas turbine plant comprising: a compressor arranged in a turbine building; a combustor arranged in the turbine building and configured to mix compressed air compressed by the compressor with fuel to generate combustion gas; a turbine arranged in the turbine building and configured to acquire rotary power by the combustion gas; an air bleeding piping configured to supply the compressed air bled off from the compressor to the turbine as cooling air; and a cooling apparatus connected to the air bleeding piping and configured to cool down the cooling air, the method comprising: arranging, outside the turbine building, auxiliary compressed air supply equipment including a separately placed compressor configured to generate compressed air and a motor configured to drive the separately placed compressor; and connecting an auxiliary compressed air piping, through which the auxiliary compressed air generated by the separately placed compressor of the auxiliary compressed air supply equipment flows, to a portion of the air bleeding piping, the portion being arranged outside the turbine building.

The above and other objects, features, advantages and technical and industrial significance of this disclosure will be better understood by reading the following detailed description of disclosed embodiments, when considered in connection with the accompanying drawings.

DETAILED DESCRIPTION

Hereinafter, the present disclosure will be described in detail, with reference to the drawings. The present disclosure is not limited by the following modes (hereinafter, referred to as “embodiments”) for carrying out the disclosure. Further, components in the embodiments described below include any component easily supposed by those skilled in the art, any component that is substantially the same, and any component of so-called equivalent scope. Furthermore, the components disclosed in the following embodiments maybe combined as appropriate.

FIG. 1is a diagram of a schematic configuration of a gas turbine plant according to a first embodiment of the present disclosure.FIG. 2is a diagram of a schematic configuration illustrating an example of a gas turbine according to the first embodiment. As illustrated inFIG. 1, a gas turbine plant100has a gas turbine102, a generator104, an auxiliary compressed air supply apparatus106, and a control apparatus108. The control apparatus108controls operation of each unit of the gas turbine plant100. The gas turbine plant100may include various structures included in a gas turbine plant, such as a flue gas treatment apparatus, which is not illustrated, and which is for treating flue gas discharged from the gas turbine102. Further, in the gas turbine plant100of this embodiment, the gas turbine102is placed in a turbine building110, the generator104is also placed in the turbine building110, and the auxiliary compressed air supply apparatus106is placed in a separately placed building112. Each unit of the gas turbine plant100arranged in the turbine building110and the separately placed building112is connected with pipings, through which compressed air flows.

As illustrated inFIG. 1andFIG. 2, the gas turbine102has a compressor1, a casing2, a combustor3, a turbine4, a turbine cooling air (TCA) line5, a turbine shaft7, a TCA cooler8, and a TCA filter9. The compressor1, the combustor3, and the turbine4are arranged in a row in order from an upstream side to a downstream side of a flow direction of compressed air or combustion gas, along a shaft center CL of the turbine shaft7. The compressor1, the casing2, the combustor3, the turbine4, a part of the TCA line5, and the turbine shaft7of the gas turbine102are placed inside the turbine building110. Further, a part of the TCA line5, the TCA cooler8, and the TCA filter9of the gas turbine102are arranged outside the turbine building110.

The compressor1compresses air into compressed air. The compressor1is arranged inside a compressor casing12having an air inlet11, through which air is taken in, and has plural stages of compressor vanes13and plural stages of compressor blades14, provided therein. The compressor vanes13of the respective stages are attached to the compressor casing12, and are arranged annularly in a circumferential direction; and the compressor blades14of the respective stages are attached to the turbine shaft7, and are arranged annularly in the circumferential direction. These plural stages of compressor vanes13and plural stages of compressor blades14are alternately provided along an axial direction.

The casing2is a so-called compressor-combustor casing, and is connected with a final stage of the compressor1, that is, a portion of the compressor1which is located closest to the turbine4. Further, the casing2is connected to the TCA line5. In the casing2, compressed air having flowed in from the compressor1is supplied to the combustor3, and some of the compressed air is supplied to the TCA line5.

By supplying fuel to the compressed air compressed by the compressor1, the combustor3generates high temperature and high pressure combustion gas. The combustor3has, for example, a combustor basket that mixes and combusts the compressed air and the fuel together, a transition piece that guides the combustion gas from the combustor basket to the turbine4, and an external cylinder that covers an outer periphery of the combustor basket and guides the compressed air from the compressor1to the combustor basket. A plurality of the combustors3is arranged in the casing2in the circumferential direction.

The turbine4generates rotary power by the combustion gas generated in the combustor3. In the turbine4, plural stages of turbine vanes32and plural stages of turbine blades33, which are arranged in a turbine casing31, are provided. The turbine vanes32of the respective stages are attached to the turbine casing31, and are arranged annularly in the circumferential direction, and the turbine blades33of the respective stages are fixed to an outer periphery of a discoidal disk centered around the shaft center CL of the turbine shaft7, and are arranged annularly in the circumferential direction. These plural stages of turbine vanes32and plural stages of turbine blades33are provided alternately along the axial direction. Downstream in the axial direction of the turbine casing31, a flue gas chamber34, which has therein a diffuser continuous with the turbine4, is provided.

One end portion of the TCA line5is connected to the casing2, and the other end portion of the TCA line5is connected to a space formed inside a rotor (rotating unit) of the turbine4. In a path of the TCA line5, the TCA cooler8and the TCA filter9are provided. The TCA line5has an air bleeding piping5athat connects the casing2to the TCA cooler8, and an air bleeding piping5bthat feeds compressed air (cooling air), which has passed through the TCA cooler8, to the rotor of the turbine4.

The TCA cooler8is a heat exchanger provided in the TCA line5. The TCA cooler8causes heat exchange between the compressed air supplied from the air bleeding piping5aand a coolant to decrease temperature of the compressed air, and discharges the heat exchanged compressed air (cooling air) to the air bleeding piping5b. The TCA filter9is arranged in the air bleeding piping5b, that is, downstream from the TCA cooler8in the flow direction of the compressed air. The TCA filter9collects foreign substances included in the compressed air. Furthermore, the heat obtained by the heat exchange between the compressed air and a coolant of the TCA cooler8may be used for heating the fuel10supplied to the combustor of the gas turbine or heating supplied water20supplied to a heat recovery steam generator (HRSG)30in gas turbine combined cycle (GTCC). In this case, total efficiency of the gas turbine can be improved.

As described above, the TCA cooler8and the TCA filter9are placed outside the turbine building110. Therefore, parts of the air bleeding pipings5aand5bof the TCA line5are drawn outside the turbine building110and connected to the TCA cooler8.

The generator104is connected to the turbine shaft7via a drive shaft105. In the generator104, by the drive shaft105rotating with the turbine shaft7, rotational energy of the turbine shaft7is converted to electric energy.

The auxiliary compressed air supply apparatus106has a separately placed compressor50, a motor52, an auxiliary compressed air piping54, a control valve56, a heat exchanger58, a blow piping60, a blow control valve62, a bypass piping64, a bypass control valve66, a first measuring unit68, a second measuring unit69, and a controller70. Each unit of the auxiliary compressed air supply apparatus106is placed in the separately placed building112.

The separately placed compressor50is a compressor provided separately from the compressor1. As the separately placed compressor50, a multistage centrifugal compressor may be used, for example.

The motor52is connected to the separately placed compressor50via the drive shaft72. By rotating the drive shaft72, the motor52rotates a rotor of the separately placed compressor50to drive the separately placed compressor50. As the motor52, a motor that rotates the separately placed compressor50by combusting fuel may be used. For example, a motor which combusts fossil fuel, such as a gas engine or a gasoline engine, may be used as the motor52.

One end portion of the auxiliary compressed air piping54is connected to the separately placed compressor50, and the other end portion thereof is connected to the TCA line5a. The auxiliary compressed air piping54has an auxiliary compressed air piping54ainside the separately placed building112, and an auxiliary compressed air piping54boutside the separately placed building112. The auxiliary compressed air piping54feeds out auxiliary compressed air, which is air compressed by the separately placed compressor50, to the TCA line5a.

The control valve56is provided in the auxiliary compressed air piping54. The control valve56is a valve that is able to cause switch-over between a state of feeding out the auxiliary compressed air, which is the air compressed by the separately placed compressor50, to the TCA line5aand a state of stopping the feeding, by being switched over between being open and being closed. Further, the control valve56may be a flow regulating valve with adjustable opening. By use of the flow regulating valve as the control valve56, flow rate of compressed air, which flows through the auxiliary compressed air piping54and is supplied to the TCA line5a, is able to be adjusted. Further, plural control valves56having different functions may be provided in the auxiliary compressed air supply apparatus106.

The heat exchanger58is arranged upstream of the control valve56in a flow direction of the auxiliary compressed air in the auxiliary compressed air piping54. The heat exchanger58has a flue gas supply flow channel74for flue gas discharged from the motor52, and performs heat exchange between the flue gas flowing through the flue gas supply flow channel74as a heating medium and the auxiliary compressed air, to increase temperature of the auxiliary compressed air. The heat exchanger58may alternatively use any fluid other than the flue gas as the heating medium, as long as the temperature of the auxiliary compressed air is able to be increased. By heating the auxiliary compressed air with heat of the flue gas from the motor52, temperature deviation between the compressed air from the compressor1and the compressed air from the separately placed compressor50can be reduced appropriately to reduce thermal stress to the air bleeding piping5awithout providing an additional heat source.

One end portion of the blow piping60is connected to a portion of the auxiliary compressed air piping54, the portion being downstream of the heat exchanger58and upstream of the control valve56in the flow direction of the auxiliary compressed air, and the other end portion thereof is open to the atmosphere. The blow control valve62is arranged in the blow piping60. The blow control valve62is an on-off valve that is able to be switched over between being open and being closed. By providing the blow piping60and blow control valve62in the auxiliary compressed air piping54, the auxiliary compressed air supply apparatus106is able to be switched over between a state where the auxiliary compressed air flowing through the auxiliary compressed air piping54is discharged from the blow piping60to the atmosphere and a state where the auxiliary compressed air flowing through the auxiliary compressed air piping54is not discharged to the atmosphere, by causing the blow control valve62to be switched between being open and being closed.

One end portion of the bypass piping64is connected to a portion of the auxiliary compressed air piping54, the portion being upstream of the heat exchanger58in the flow direction of the auxiliary compressed air, and the other end portion thereof is connected to a portion of the auxiliary compressed air piping54, the portion being downstream of the heat exchanger58and upstream of the portion connected to the blow piping60in the flow direction of the auxiliary compressed air. That is, the bypass piping64is a piping, through which the auxiliary compressed air flowing through the auxiliary compressed air piping54can bypass the heat exchanger58. The bypass control valve66is arranged in the bypass piping64. The bypass control valve66is a flow regulating valve, and by adjustment of its opening, ratio between compressed air passing through the heat exchanger58and compressed air bypassing the heat exchanger58is adjusted. By causing the auxiliary compressed air to bypass the heat exchanger58by the bypass piping64when overheating the auxiliary compressed air, temperature deviation between the compressed air from the compressor1and the compressed air from the separately placed compressor50can be reduced appropriately to reduce thermal stress to the air bleeding piping5awithout providing an additional heat source.

The first measuring unit68is arranged at a portion of the auxiliary compressed air piping54, the portion being between the separately placed compressor50and the heat exchanger58. The first measuring unit68measures a state of the auxiliary compressed air discharged from the separately placed compressor50. The second measuring unit69is arranged at a portion of the auxiliary compressed air piping54, the portion being between the portion connected to the bypass piping64and the control valve56. The second measuring unit69measures a state of the auxiliary compressed air after parts of the auxiliary compressed air which have flowed through the auxiliary compressed air piping54and of which one part has passed through the heat exchanger58and the other part has passed through the bypass piping64join with each other. The first measuring unit68and the second measuring unit69measure temperature and pressure as the states of the auxiliary compressed air.

Based on a command from the control apparatus108and results of the measurement by the first measuring unit68and second measuring unit69, the controller70controls operation of each unit of the auxiliary compressed air supply apparatus106, specifically, each of the motor52, the control valve56, the blow control valve62, and the bypass control valve66.

Next, operation of the gas turbine plant100will be described with reference toFIG. 1,FIG. 2,FIG. 3AandFIG. 3B.FIGS. 3A and 3Bare explanatory diagrams each illustrating an example of the operation of the gas turbine plant according to the first embodiment.FIG. 3Aillustrates operation of the gas turbine plant in a stopped state of the auxiliary compressed air supply apparatus106.FIG. 3Billustrates operation of the gas turbine plant in an operating state of the auxiliary compressed air supply apparatus106.

Firstly, the operation of the gas turbine plant100when the auxiliary compressed air supply apparatus106is in the stopped state will be described with reference toFIG. 3A. In the gas turbine plant100illustrated inFIG. 3A, the control valve56is closed. In the gas turbine plant100, when the turbine shaft7is rotated, air is taken in from the air inlet11of the compressor1. The air taken into the compressor1is compressed by passing through the plural stages of the compressor vanes13and plural stages of the compressor blades14, thereby becoming high temperature and high pressure compressed air. Compressed air130generated in the compressor1flows into the casing2, and compressed air132, which is a part of the compressed air130, is supplied to the combustor3. Further, compressed air134, which is another part of the compressed air130, is supplied to the air bleeding piping5afrom the casing2.

In the gas turbine plant100, the combustor3mixes fuel into the compressed air132to combust the fuel and thereby generates combustion gas. In the gas turbine plant100, by the combustion gas passing through the plural stages of the turbine vanes32and plural stages of the turbine blades33of the turbine4, the turbine shaft7is rotationally driven. In the gas turbine plant100, by the turbine shaft7rotating and the drive shaft105rotating integrally with the turbine shaft7, the generator104generates electricity. Further, the combustion gas after the turbine shaft7is rotationally driven is discharged from the flue gas chamber34to outside of the system.

Further, of the compressed air130compressed by the compressor1, the compressed air134supplied to the air bleeding piping5ais cooled down by passing through the TCA cooler8, and foreign substances therein is removed by the TCA filter9. The compressed air134is supplied to the rotor of the turbine4, that is, to the turbine shaft7and the turbine blades33to cool down the turbine shaft7and the turbine blades33.

When atmospheric temperature increases, density of air is decreased and mass flow rate of air taken in by the compressor1is reduced, and thus gas turbine output is reduced. In the gas turbine plant100of this embodiment, the auxiliary compressed air supply apparatus106is activated in order to increase the gas turbine output reduced due to the above mentioned reason when the gas turbine102is operating at a rated value.

When the auxiliary compressed air supply apparatus106is activated, the controller70drives the motor52to cause the separately placed compressor50to generate compressed air. Upon the activation, the controller70closes the control valve56and opens the blow control valve62. Upon the activation, the auxiliary compressed air discharged from the separately placed compressor50is in a state of having pressure lower than a predetermined pressure and also having low temperature, and thus is discharged outside from the blow piping60. Further, the controller70adjusts the opening of the bypass control valve66to adjust flow rate of the auxiliary compressed air passing through the heat exchanger58.

The controller70opens the control valve56when a state of the auxiliary compressed air measured by the second measuring unit69satisfies a predetermined condition. This predetermined condition may be, for example, a pressure of the auxiliary compressed air being a value higher than a pressure of the compressed air132flowing into the casing2and a temperature of the auxiliary compressed air being a value close to a temperature of the compressed air130flowing into the casing2. When the control valve56is opened, supply of the auxiliary compressed air from the auxiliary compressed air supply apparatus106to the gas turbine102is started.

In the gas turbine plant100, by the control valve56being opened, as illustrated inFIG. 3B, the auxiliary compressed air140is supplied to the air bleeding piping5a, to which the auxiliary compressed air piping54bis connected, from the auxiliary compressed air supply apparatus106. In the gas turbine plant100, by the supply of the auxiliary compressed air140, as compared to the stopped state of the auxiliary compressed air supply apparatus106, of the compressed air130generated by the compressor1, the compressed air134supplied from the casing2to the air bleeding piping5ais reduced and compressed air132asupplied to the combustor3is increased. Thereby, in the gas turbine plant100, more of the compressed air130generated by the compressor1is able to be supplied to the combustor3, and the flow rate of the combustion gas generated by the combustor3is able to be increased. Therefore, the gas turbine plant100enables the gas turbine output to be increased and the electric power generation to be increased. Further, since the auxiliary compressed air140supplied from the auxiliary compressed air supply apparatus106is supplied to the gas turbine102as the cooling air, each unit of the gas turbine102is able to be cooled down appropriately.

As described above, the gas turbine plant100of this embodiment includes the auxiliary compressed air supply apparatus106, which has the separately placed compressor50that is able to supply the auxiliary compressed air140, which is compressed air different from the compressed air130generated by the compressor1, to the gas turbine102. Thus, the gas turbine plant100enables the gas turbine output to be increased, by use of the compressed air130compressed by the compressor1and the auxiliary compressed air140compressed by the separately placed compressor50.

Further, the gas turbine plant100of this embodiment enables the amount of compressed air, which is a part of the compressed air130generated by the compressor1and used as the cooling air for cooling down the rotor of the turbine4, to be reduced or to be zero, by use of the auxiliary compressed air140supplied from the auxiliary compressed air supply apparatus106as the cooling air for cooling down the rotor of the turbine4. Thereby, while the flow rate of the compressed air supplied to the combustor3from the compressed air130generated by the compressor1is able to be increased, the cooling air for cooling the rotor of the turbine4is able to be acquired.

In the gas turbine plant100, the auxiliary compressed air piping54, through which the auxiliary compressed air140compressed by the separately placed compressor50flows, is connected to the TCA line5. Specifically, the auxiliary compressed air piping54is connected to the air bleeding piping5athat feeds out the compressed air (cooling air) bled off from the casing2to the TCA cooler8. That is, the auxiliary compressed air140supplied from the auxiliary compressed air supply apparatus106passes through the TCA line5having the TCA cooler8and the TCA filter9, to be supplied to the gas turbine102and used as the cooling air for cooling down the rotor of the turbine4.

Thereby, as compared to, for example, a case of a structure where auxiliary compressed air is supplied to a casing (compressor-combustor casing) like of a conventional technique, the gas turbine plant100of this embodiment can suppress change of the compressed air supplied to the combustor3. That is, by the auxiliary compressed air and the compressed air being mixed and supplied to the combustor3, fluctuation in the combustion state in the combustor3can be reduced. Therefore, deviation in density of air for combustion due to a temperature difference between the auxiliary compressed air and the compressed air, and resulting difference in the combustion state among the combustors can be reduced or prevented. Therefore, limit on the operation due to an interlock caused by increase in the deviation of temperature of the combustion gas flowing in the flue gas chamber34, and adverse influence on the turbine parts due to ununiformity of flow of the combustion gas inside the turbine caused by the deviation of temperature of the combustion gas can be reduced.

Further, for supplying auxiliary compressed air to a casing like in the conventional technique, a structure, where a manifold or the like is provided to supply the auxiliary compressed air from plural positions in a circumferential direction of the casing, may be considered. However, due to insufficient space around the casing, the structure becomes a structure circumventing existing pipings, and thus a manifold with a complex shape needs to be provided therein. In contrast, since the gas turbine plant100of this embodiment has the structure, where the auxiliary compressed air piping54bis connected to the air bleeding piping5aplaced outside the turbine building110, the structure for supplying the auxiliary compressed air is able to be simplified.

Furthermore, the gas turbine plant100of this embodiment enables generation of thermal stress in the air bleeding piping5ato be reduced by decreasing the temperature difference between the compressed air130generated by the compressor1and the auxiliary compressed air140supplied from the auxiliary compressed air supply apparatus106. Moreover, by the structure, where the auxiliary compressed air piping54bfor supplying the auxiliary compressed air140is connected upstream of the TCA cooler8, the gas turbine plant100of this embodiment enables the changes in the cooling air supplied to the rotor of the turbine4to be small between the case where the compressed air134is used as the cooling air and the case where the auxiliary compressed air140is used as the cooling air. Therefore, even if the auxiliary compressed air140is used as the cooling air for the rotor of the turbine4, cooling effect, which is the same as that in the case where the compressed air134is used as the cooling air, is able to be obtained. Furthermore, the auxiliary compressed air piping54bconnected to the air bleeding piping5amay be connected downstream of the TCA cooler8. In this case, an effect of being able to increase flow rate of gas flowing to the gas turbine to improve output of the gas turbine while suppressing increase in load on the gas turbine, is achieved, as in the case in which the auxiliary compressed air piping54bis connected to upstream of the TCA cooler8.

In the gas turbine plant100of this embodiment, the controller70starts supplying the auxiliary compressed air140, when pressure of the auxiliary compressed air140becomes higher than pressure of the compressed air132supplied to the casing2from the compressor1. Therefore, even if a control valve is not provided in the air bleeding piping5a, through which the compressed air134flows, the supplied auxiliary compressed air140flows into the air bleeding piping5aand flows towards the TCA cooler8. Further, even if the supply of the auxiliary compressed air140from the auxiliary compressed air supply apparatus106is stopped due to an unexpected phenomenon, the compressed air134generated by the compressor1flows into the air bleeding piping5a, and thus cooling of the rotor of the turbine4is able to be maintained appropriately.

The gas turbine plant100of the above described embodiment can also be realized by an improvement of installing the auxiliary compressed air supply apparatus106in an existing gas turbine plant not including the auxiliary compressed air supply apparatus106.

Hereinafter, an example of a method of the improvement will be described with reference toFIG. 4AtoFIG. 4C. Each ofFIGS. 4A to 4Cis a diagram of a schematic configuration illustrating the example of the method of improving an existing gas turbine plant. An existing gas turbine plant200has, as illustrated inFIG. 4A, the gas turbine102and the generator104. The gas turbine102and the generator104include the same units as the above described gas turbine plant100and description thereof will be omitted. Further, the gas turbine plant200also includes a control apparatus, and the like. The compressor1, the turbine4, the generator104, and the like of the existing gas turbine plant200are installed in the turbine building110. Further, the TCA cooler8, the TCA filter9, and a part of the TCA line5connected thereto are installed outside the turbine building110. The TCA cooler8and the TCA filter9are installed outside the turbine building110, and the air bleeding piping5aconnecting the compressor1to the TCA cooler8, and the air bleeding piping5bconnecting the TCA cooler8to the turbine4extend from inside of the turbine building110to outside of the turbine building110.

When the existing gas turbine plant200is to be improved, the separately placed compressor50, the motor52, the auxiliary compressed air piping54a, the control valve56, and the heat exchanger58of the auxiliary compressed air supply apparatus106are installed outside the turbine building110of the existing gas turbine plant200aas illustrated inFIG. 4B. In addition, the blow piping60, the blow control valve62, the bypass piping64, the bypass control valve66, the first measuring unit68, the second measuring unit69, and the controller70may be installed further. That is, the units other than the auxiliary compressed air piping54bof the auxiliary compressed air supply apparatus106are installed. Further, in this embodiment, the separately placed compressor50, the motor52, the auxiliary compressed air piping54a, the control valve56, and the heat exchanger58are installed inside the separately placed building112.

As illustrated in the existing gas turbine plant200a, after the separately placed compressor50, the motor52, the auxiliary compressed air piping54a, the control valve56, and the heat exchanger58are installed, the auxiliary compressed air piping54bis connected to the air bleeding piping5aarranged outside the turbine building110when the operation of the gas turbine102is in the stopped state. Thereby, the auxiliary compressed air supply apparatus106is able to be connected to the gas turbine102in the existing gas turbine plant200billustrated inFIG. 4C, and the improvement of providing the auxiliary compressed air supply apparatus106in the existing gas turbine plant200is able to be realized.

In this method of improving an existing gas turbine plant according to this embodiment, by providing the auxiliary compressed air supply apparatus106outside the turbine building110, each unit of the auxiliary compressed air supply apparatus106is able to be installed when the existing gas turbine plant is in operation. Further, by this method of improving an existing gas turbine plant, work other than the work of connecting the auxiliary compressed air piping54to the air bleeding piping5bis able to be performed without stopping the gas turbine. Thereby, during the work of the improvement, the operation of the gas turbine plant is able to be continued. Furthermore, since the work required to be done with the gas turbine stopped can be reduced, the improvement can be performed during a period of periodical check of the gas turbine plant, and thus the improvement is able to be performed with less influence on the operation of the gas turbine plant.

Further, in the method of improving an existing gas turbine plant, since a piping for supplying compressed air from the auxiliary compressed air supply apparatus106is installed in the TCA line, the piping is able to be installed in a portion arranged outside the turbine building110. As described above, since the air bleeding piping5ais outside the building, when the auxiliary compressed air piping54of the auxiliary compressed air supply apparatus106is connected to the air bleeding piping5a, there is no need to work by carrying a part of the auxiliary compressed air supply apparatus106into the turbine building110. Thereby, labor of a worker carrying the auxiliary compressed air supply apparatus106into the turbine building110is saved, and thus the work is able to be simplified and made highly efficient.

In the gas turbine plant100of the first embodiment, the auxiliary compressed air140is used as the rotor cooling air for cooling the turbine4. In this case, even if the auxiliary compressed air140is used as the cooling air for the rotor of the turbine4, cooling effect that is the same as that in a case where the compressed air134is used as the cooling air is able to be obtained, but the present disclosure is not limited to this embodiment. In the gas turbine plant, the auxiliary compressed air may be used as cooling air for others.

FIG. 5is a diagram of a schematic configuration illustrating an example of a gas turbine plant according to a second embodiment.FIG. 6is a diagram of a schematic configuration illustrating an example of a gas turbine and an auxiliary compressed air supply apparatus, according to the second embodiment. A gas turbine plant100aillustrated inFIG. 5has a gas turbine102a, the generator104, an auxiliary compressed air supply apparatus106a, and the control apparatus108. Since the generator104and the control apparatus108have the same configurations as those of the gas turbine plant100, description thereof will be omitted.

The gas turbine102ais configured similarly to the gas turbine102, and has the compressor1, the casing2, the combustor3, the turbine4, the turbine cooling air (TCA) line5, the turbine shaft7, the TCA cooler8, and the TCA filter9. Further, the gas turbine102aincludes a turbine blade cooling mechanism6. The gas turbine102may also include the turbine blade cooling mechanism6.

The turbine blade cooling mechanism6bleeds off the compressed air from stages in the middle of the compressor1, and supplies the bled compressed air to a blade ring and turbine vanes of the turbine4to cool them down. The turbine blade cooling mechanism6bleeds off the compressed air from three stages in the middle of the compressor1, and cools down the turbine vanes of separate stages of the turbine4respectively with the compressed air from the three stages.

The turbine blade cooling mechanism6has air bleeding pipings202a,202b, and202c, and check valves204a,204b, and204c. Portions at one end of the air bleeding pipings202a,202b, and202care connected to the compressor1, and portions at the other end thereof are connected to the turbine4. The air bleeding piping202ais connected to a position at which the compressed air and the combustion gas with higher pressure than those in the air bleeding piping202bflow. The air bleeding piping202bis connected to a position at which the compressed air and combustion gas with higher pressure than those in the air bleeding piping202cflow. The check valve204ais provided in the air bleeding piping202a. The check valve204bis provided in the air bleeding piping202b. The check valve204cis provided in the air bleeding piping202c. The check valves204a,204b, and204care valves, each of which restricts flow of compressed air to one direction, such that the compressed air flows from the compressor1towards the turbine4and the compressed air does not flow from the turbine4towards the compressor1. The turbine blade cooling mechanism6supplies the compressed air bled off from the compressor1to the turbine4, and causes the compressed air to pass through the turbine vanes, blade ring, casing, and the like of the turbine4, to thereby cool them down in the region where the compressed air passed through. The compressed air supplied from the turbine blade cooling mechanism6to the turbine4is discharged, as film air or seal air, to a flow channel, through which combustion gas flows, or supplied to another region as cooling air for a lower pressure region.

The auxiliary compressed air supply apparatus106ahas the separately placed compressor50, the motor52, the control valve56, supply pipings220,222, and224, recovery pipings226,228, and230, and a control valve231. Similarly to the auxiliary compressed air supply apparatus106, the auxiliary compressed air supply apparatus106amay include the heat exchanger58, the blow piping60and blow control valve62, the bypass piping64and bypass control valve66, a measuring unit, a controller, and the like. Since the separately placed compressor50, the motor52, and the control valve56have the same configurations as the respective units of the auxiliary compressed air supply apparatus106, description thereof will be omitted.

The auxiliary compressed air supply apparatus106ahas, as pipings through which compressed air generated by the separately placed compressor50flows, the supply pipings220,222, and224and the recovery pipings226,228, and230. One end portion of the supply piping220is connected to the separately placed compressor50, and the other end portion thereof is connected to the supply piping222and the supply piping224. One end portion of the supply piping222is connected to the supply piping220, and the other end portion thereof is connected to the air bleeding piping202a. One end portion of the supply piping224is connected to the supply piping220, and the other end portion thereof is connected to the air bleeding piping202b. One end portion of the recovery piping226is connected to the turbine4, and the other end portion thereof is connected to the recovery piping230. One end portion of the recovery piping228is connected to the turbine4, and the other end portion thereof is connected to the recovery piping230. One end portion of the recovery piping230is connected to the recovery piping226and recovery piping228, and the other end portion thereof is connected to the casing2. The control valve231is provided in the recovery piping230. The control valve231is a valve for switching over between supplying and not supplying air having flowed into the recovery piping230to the casing2.

Next, a path through which the auxiliary compressed air flows will be described with reference toFIG. 6. As illustrated inFIG. 6, the plural stages of turbine vanes32of the turbine4include, in order from an upstream side in a flow direction FG of the combustion gas, a first turbine vane32a, a second turbine vane32b, a third turbine vane32c, and a fourth turbine vane32d. The turbine vane32is integrally formed of an outer shroud51, an airfoil portion53extending to an inner side in a radial direction from the outer shroud51, and an inner shroud (not illustrated) provided at an inner side in the radial direction of the airfoil portion53. Further, the turbine vane32is supported on the turbine casing31via a thermal insulation ring and a blade ring, and constitutes a part of a fixed side.

The plural stages of turbine blades33are respectively arranged opposite to plural ring segments52at an inner side in the radial direction. The turbine blades33of the respective stages are provided separately from the respective ring segments52with a predetermined gap therebetween, and constitute a part of a movable side. The plural stages of turbine blades33include, from the upstream side in the flow direction FG of the combustion gas, in the order of a first turbine blade33a, a second turbine blade33b, a third turbine blade33c, and a fourth turbine blade33d.

Therefore, the plural stages of turbine vanes32and the plural stages of turbine blades33are arranged, in order from the upstream side in the flow direction FG of the combustion gas, to have the first turbine vane32a, the first turbine blade33a, the second turbine vane32b, the second turbine blade33b, the third turbine vane32c, the third turbine blade33c, the fourth turbine vane32d, and the fourth turbine blade33d, and are provided opposite to each other in the axial direction.

As illustrated inFIG. 6, the turbine casing31has a blade ring45arranged at an inner side of the turbine casing31in the radial direction and supported on the turbine casing31. The blade ring45is formed around the turbine shaft7in an annular shape, plurally divided in the circumferential direction and the axial direction, and supported on the turbine casing31. A thermal insulation ring46is arranged at an inner side of the blade ring45in the radial direction, and the turbine vanes32are supported on the blade ring45via the thermal insulation ring46. Inside the blade ring45, the plural turbine vanes32and the plural ring segments52are provided adjacent to each other in the axial direction.

The supply piping222is connected to a space formed over an outer shroud51a(51) of the first turbine vane32aand a space formed over a ring segment52a(52) forming the blade ring facing the first turbine blade33a. Further, in the turbine4, a space formed in the blade ring outside the outer shroud51a(51) is connected to a cooling passage232formed in the outer shroud51aof the first turbine vane32aand the airfoil portion53. Furthermore, the cooling passage232is connected to the recovery piping226.

Next, the supply piping224is connected to a space formed over an outer shroud51b(51) of the second turbine vane32band a space formed over a ring segment52b(52) forming the blade ring facing the second turbine blade33b. Further, in the turbine4, a space formed in the blade ring outside the outer shroud51b(51) is connected to a cooling passage234formed in the outer shroud51bof the second turbine vane32band the airfoil portion53. Furthermore, the cooling passage234is connected to the recovery piping228.

In the gas turbine plant100a, when the auxiliary compressed air supply apparatus106ais in a stopped state, the control valve56and the control valve231are closed. In this case, in the gas turbine plant100a, the compressed air bled off from the compressor1in the turbine blade cooling mechanism6is supplied to the turbine4, and the respective parts of the turbine4are cooled down.

The auxiliary compressed air supply apparatus106ais operated in order to increase the gas turbine output, similarly to the auxiliary compressed air supply apparatus106. When a state of the auxiliary compressed air satisfies a predetermined condition, the auxiliary compressed air supply apparatus106aopens the control valve56and the control valve231. As to the predetermined condition, for example, when a pressure of the auxiliary compressed air generated by the separately placed compressor50of the auxiliary compressed air supply apparatus106abecomes a suppliable pressure, that is, when a value of the pressure of the auxiliary compressed air becomes a value higher than a pressure of the compressed air supplied in the turbine blade cooling mechanism6, the control valve56and the control valve231are opened. When the control valve56and the control valve231are opened, supply of the auxiliary compressed air to the turbine4is started from the auxiliary compressed air supply apparatus106a, through the supply pipings220,222, and224.

The auxiliary compressed air supplied from the supply piping222passes through the cooling passage232of the first turbine vane32aafter passing through the space formed in the blade ring outside the outer shroud51a(51). The auxiliary compressed air that has passed through the cooling passage232flows into the casing2after passing through the recovery piping226and the recovery piping230. Further, the auxiliary compressed air supplied from the supply piping224passes through the cooling passage234of the second turbine vane32bafter passing through the space formed in the blade ring outside the outer shroud51b(51). The auxiliary compressed air that has passed through the cooling passage234flows into the casing2after passing through the recovery piping228and the recovery piping230. Furthermore, similarly to the compressed air, some of the auxiliary compressed air is discharged, as seal air and film air, into the flow channel, through which the combustion gas flows. The auxiliary compressed air, which has flowed through the respective parts, has been used as the cooling air, and has been supplied from the recovery piping230to the casing2, is supplied, to the combustor3together with the compressed air discharged from the compressor1.

Thereby, in the gas turbine plant100a, flow rate of the compressed air, which is a part of the compressed air compressed by the compressor1and supplied to the turbine4without passing through the combustor3for cooling, can be reduced. Thereby, more of the compressed air compressed by the compressor1is able to be supplied to the combustor.

Further, in the gas turbine plant100aof this embodiment, the auxiliary compressed air compressed to a necessary pressure by the separately placed compressor50is fed to the blade ring of the turbine4, and the turbine blade ring is cooled down by that auxiliary compressed air. Furthermore, in the gas turbine plant100a, the auxiliary compressed air used in cooling the blade ring of the turbine4is fed to the first turbine vane32aand second turbine vane32b, and the turbine vanes of the respective stages are cooled down by the auxiliary compressed air. In the gas turbine plant100a, the auxiliary compressed air that has cooled down the respective turbine vanes is recovered through the recovery pipings226and228connected to the cooling passages of the turbine vanes of the respective stages, and the recovered compressed air is supplied to the combustor3to be used as combustion air for gas turbine. In the gas turbine plant100a, by using the auxiliary compressed air for cooling the turbine blade ring and turbine vanes, the flow rate of the compressed air compressed by the compressor and supplied as the cooling air to the turbine vanes can be reduced, and the flow rate of the compressed air flowing out to the flow channel of the combustion gas after being passed inside the turbine vanes can be reduced. Moreover, by recovering some of the auxiliary compressed air, even if the compressed air flowing through the turbine vanes and the like is increased, decrease in efficiency can be reduced.

In addition, in the gas turbine plant100a, another compressor, which increases pressure of the auxiliary compressed air flowing through the recovery pipings, may be further provided separately.

The present disclosure has been made in view of the above, and can provide a gas turbine plant and a method of improving an existing gas turbine plant, which can suppress increase in load on a gas turbine, and increase flow rate of gas flowing to the gas turbine to improve output of the gas turbine.

According to the present disclosure, more of compressed air supplied from a compressor of a gas turbine is able to be used in combustion, by supplying compressed air supplied from a separately placed compressor as cooling air. Thereby, an effect of being able to increase flow rate of gas flowing to the gas turbine to improve output of the gas turbine while suppressing increase in load on the gas turbine, is achieved.