Transition Piece Cooling Holes for Gas Turbine Combustor

There are provided transition piece cooling holes which make NOx reduction and combustion performance improvement possible while effectively cooling the transition piece end frame and the first-stage stator vane end wall. The transition piece cooling holes include a transition piece which guides combustion gas from a combustor to a turbine, a transition piece end frame which is installed on a turbine-side outlet of the transition piece and is disposed so as to face a first-stage stator vane end wall of the turbine with a predetermined gap being interposed, and a seal member which is fitted on the transition piece end frame and is fitted into the first-stage stator vane end wall so as to seal cooling air which is supplied into the gap. The cooling holes are made in the transition piece end frame so as to directly supply the cooling air to the first-stage stator vane end wall.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent application serial no. 2020-126388, filed on Jul. 27, 2020, the content of which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to transition piece cooling holes and particularly relates to a technology which is effectively applied to a transition piece end frame structure.

In a gas turbine for use in a general power plant and a general mechanical drive, high-pressure air which is introduced from an air compressor is introduced into a cabin through a diffuser and flows into the cabin by being divided into part to be used in a burner unit as air for combusting the combustor and part to be used for cooling the combustor and a gas turbine main body.

Combustion gas which is generated by combustion of a fuel-air mixture in the combustor is introduced into a turbine blade through a transition piece. A workload which is generated when the high-temperature and high-pressure combustion gas which is introduced into the turbine blade is adiabatically expanded is converted to axle rotational force by the turbine and thereby output is obtained from a generator.

In addition, there also exists a mechanical drive use plant which uses the gas turbine as a power source for fluid compression by rotating another compressor in place of the generator by utilizing this axle rotational force.

As a background technology in this technical field, there exists a technology which is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2013-221455. In Japanese Unexamined Patent Application Publication No. 2013-221455, “In a gas turbine high-temperature component which defines a combustion gas flow passage that combustion gas flows, the gas turbine high-temperature component in which a groove which depresses from an end face which faces another high-temperature component which is adjacent thereto along the combustion gas passage in a direction away from another high-temperature component and extends in an direction that the end face extends, a cooling passage which extends in the direction that the end face extends in a region which is sandwiched between the groove and the combustion gas passage, an introduction passage which connects the groove with the cooling passage, and an exhaust passage which connects the cooling passage with the combustion gas flow passage are formed” is disclosed.

In addition, in Japanese Unexamined Patent Application Publication No. 2007-120504, “A combustor cooling structure which includes, on a wall of a combustor transition piece, a brim which is provided on an outer periphery of the combustor transition piece which is located on a rear end which is the combustion gas discharge side and projects outward from the combustor transition piece, a transition piece seal which has a hook shape which fits on the brim, is fixed by fitting on the brim and is provided at a position where it faces an end face of the rear end of the combustor transition piece, a plurality of cooling flow grooves which are provided so as to extend in an axial direction of the combustor transition piece in the wall part of the combustor transition piece, at least some of which penetrate down to the end face of the rear end of the combustor transition piece and in which a cooling medium flows, and a through-hole which is provided in the end face of the rear end of the combustor transition piece and through which the cooling medium is discharged from the cooling flow grooves which are in the form of penetrating down to the rear end of the combustor transition piece and in which the cooling medium which is discharged through the through-hole is blown against the transition piece seal” is disclosed.

SUMMARY OF THE INVENTION

Since the transition piece which connects the burner of the combustor with the turbine blade is exposed to the high-temperature combustion gas, it is necessary to cool the transition piece by using part of compressor discharge air. In general, structures such as a film cooling structure which protects the transition piece with an air film which is formed by injecting a fluid through a cooling hole, a convection cooling structure which cools an outer face of the transition piece with the compressor discharge air and thereby lowers the temperature of an inner metal surface of the transition piece, and so forth are adopted.

In addition, since the turbine blade is also exposed to the high-temperature combustion gas, it is necessary to lower a metal temperature by a structure of cooling the inside of the blade, the film cooling structure, and so forth.

However, in a case where cooling air is used in both the combustor and the turbine blade, such a problem arises that a local fuel-to-air ratio (a fuel-air ratio) is increased in the burner unit due to a reduction in gas turbine efficiency and a reduction in air used for combustion, the combustion gas temperature rises and also the metal temperature rises. Local combustion gas temperature rising leads to a rise of concentration of NOx (nitrogen oxides) in exhaust gas and the metal temperature rising leads to reductions in reliability and durability of high-temperature components.

In Japanese Unexamined Patent Application Publication No. 2013-221455 which is described above, although compressed air A is in contact with a corner of a stator vane shroud (an inner-side shroud45), it does not show impingement cooling effects regarding impact angle of cooling air, and it is difficult to sufficiently cool the stator vane shroud (the inner-side shroud45). In addition, a seal member is interposed between the transition piece end frame, and the turbine inlet and the cooling holes are made in the seal member.

In Japanese Unexamined Patent Application Publication No. 2007-120504 which is described above, for example, as illustrated inFIG. 11C, although cooling of a transition piece main body5and a first-stage stator vane shroud16is taken into consideration, in general, cooling of the transition piece end frame which is installed on the outlet part of the transition piece is not taken into consideration.

Accordingly, the present invention aims to provide transition piece cooling holes and make NOx reduction and combustion performance improvement possible while effectively cooling the transition piece end frame and the first-stage stator vane end wall.

In order to solve the abovementioned problems, according to one embodiment of the present invention, there are provided transition piece cooling holes which include a transition piece which guides combustion gas from a combustor to a turbine, a transition piece end frame which is installed on a turbine-side outlet of the transition piece and is disposed so as to face a first-stage stator vane end wall of the turbine with a predetermined gap being interposed, and a seal member which is fitted on the transition piece end frame and is fitted into the first-stage stator vane end wall so as to seal cooling air which is supplied into the gap, in which the cooling holes are arranged in the transition piece end frame so as to directly supply the cooling air to the first-stage stator vane end wall.

According to the present invention, it becomes possible to realize the transition piece cooling holes which make it possible to attain the NOx reduction and the combustion performance improvement while effectively cooling the transition piece end frame and the first-stage stator vane end wall.

Accordingly, it becomes possible to realize the high-performance transition piece cooling holes which is excellent in reliability and durability.

Subject matters, configurations and effects other than the above will become apparent from description of the following embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of the present invention will be described by using the drawings. Incidentally, in the respective drawings, the same reference numerals are assigned to the same constitutional elements and detailed description of overlapped parts will be omitted.

First Embodiment

First, transition piece cooling holes which become the subject matter of the present invention and the ever-present problems will be described with reference toFIG. 1,FIG. 2, andFIG. 15.FIG. 1is a diagram illustrating one configuration example of a general gas turbine.FIG. 2is a diagram illustrating one configuration example of a general combustor, in which the combustor is illustrated in the form of a combustor which includes a transition piece4and a transition piece end frame6.FIG. 15is a sectional diagram illustrating one example of an existing transition piece end frame structure.

As illustrated inFIG. 1, the gas turbine is roughly configured by a compressor1, a combustor2, and a turbine3. The compressor1adiabatically compresses air which is sucked from the atmosphere as a working fluid. The combustor2burns fuel by mixing compressed air which is supplied from the compressor1with the fuel and thereby generates high-temperature and high-pressure combustion gas. Then, in the turbine3, when the combustion gas which is introduced from the combustor2expands, rotational force is generated. Air which is exhausted from the turbine3is released into the atmosphere.

As illustrated inFIG. 2, the transition piece4which guides the combustion gas from the combustor2to the turbine3is installed between the combustor2and the turbine3(in a combustion gas flowing direction5). A flow sleeve (not illustrated) is installed around the transition piece4. Cooling air which is discharged from the compressor1is taken in between the flow sleeve and the transition piece4, the cooling air flows along a cooling air passage which is formed between the flow sleeve and the transition piece4and thereby the transition piece4is cooled with the cooling air. The transition piece end frame6which is a reinforcement member is installed on a turbine3side outlet part of the transition piece4.

As illustrated inFIG. 15, the existing transition piece end frame6is disposed to face a first-stage stator vane end wall10(generally, called a “retainer ring”) with a predetermined gap interposed therebetween, and the transition piece end frame6and the first-stage end wall (the retainer ring)10are fitted into and fitted on a seal member11which seals the cooling air which is supplied into the gap respectively.

Cooling holes26and28which take in part of the cooling air which flows between the abovementioned flow sleeve and the transition piece4are made in the transition piece end frame6, and the cooling air flows through the cooling holes26and28in flowing directions27and29and thereby the transition piece end frame6is cooled with the cooling air.

The cooling holes26and28which are made in this transition piece end frame6are drilled through the transition piece end frame6from the outer circumference side of the transition piece4(the transition piece end frame6) toward a gas path face (a combustion gas flowing face) which is located on the inner circumference side of the transition piece4for the purpose of cooling the transition piece end frame6.

On the other hand, the first-stage stator vane end wall10is cooled for promoting a reduction in metal temperature with the aid of a cooling slit (not illustrated) which is formed in the first-stage stator vane end wall10. It is necessary to supply the cooling air also to the cooling slit and thereby a reduction in efficiency of the entire gas turbine is induced.

Next, a transition piece end frame structure according to the first embodiment of the present invention will be described with reference toFIG. 3andFIG. 4.FIG. 3is an enlarged diagram of an area A inFIG. 2and is a sectional diagram illustrating one example of the transition piece end frame structure in the first embodiment of the present invention.FIG. 4is an enlarged diagram of an area B inFIG. 3.

As illustrated inFIG. 3andFIG. 4, in the first embodiment, the transition piece cooling holes include the transition piece4which guides the combustion gas from the combustor2to the turbine3, the transition piece end frame6which is disposed on the turbine3side outlet part of the transition piece4and is arranged so as to face the first-stage stator vane end wall10of the turbine3with the predetermined gap interposed therebetween, and the seal member11which is fitted on the transition piece end frame6and fitted into the first-stage stator vane end wall10respectively thereby to seal the cooling air which is supplied into the predetermined gap.

A cooling hole12through which the cooling air is directly supplied to the first-stage stator vane end wall10is made in the transition piece end frame6so as to extend through the inside thereof. The cooling air flows in the cooling hole12in a flowing direction13and thereby the transition piece end frame6is cooled with the cooling air from the inside and also the first-stage stator vane end wall10is cooled with the cooling air.

In the first embodiment, the transition piece cooling holes are configured as described above, and therefore it becomes possible to reduce the amount of the cooling air which is used to cool high-temperature components while effectively cooling both the transition piece end frame6and the first-stage stator vane end wall10and to suppress local temperature rising of the combustion gas which is induced by a reduction in amount of air used for combustion. Thereby, it becomes possible to promote improvement of the reliability and the durability, the NOx reduction, and the combustion performance improvement of the gas turbine.

Incidentally, as illustrated inFIG. 4, it is desirable that the cooling hole12be made to have a predetermined inclination angle relative to the inner circumferential surface of the transition piece end frame6in order to supply the cooling air directly to an inner- circumference-side inclined part of the first-stage stator vane end wall10. This is because the inner- circumference-side inclined part of the first-stage stator vane end wall10is thinned and therefore high-temperature oxidation thinning which is induced with the high-temperature combustion gas, thermal stress cracking, and so forth are liable to occur. In addition, it becomes possible to obtain not only the effect of film cooling but also the effect of impingement cooling and it becomes possible to increase cooling efficiency.

Second Embodiment

A transition piece end frame structure according to the second embodiment of the present invention will be described with reference toFIG. 5andFIG. 6.FIG. 5is a sectional diagram illustrating one example of the transition piece end frame structure in the second embodiment, and the upper side and the lower side of the transition piece4are illustrated inFIG. 5respectively.FIG. 6is a sectional diagram illustrating one example of an almost half area of a C-C′ section inFIG. 5.

As illustrated inFIG. 5, in the second embodiment, the transition piece cooling holes are configured such that an angle of inclination of one cooling hole12which is made in an inner part of the transition piece end frame6which is located on the upper side of the transition piece4relative to the inner circumferential surface of the transition piece end frame6is made different from an angle of inclination of another cooling hole12which is made in an inner part of the transition piece end frame6which is located on the lower side of the transition piece4relative to the inner circumferential surface of the transition piece end frame6.

It becomes possible to supply the cooling air directly to respective desirable parts of the first-stage stator vane end wall10on the upper side and the lower side of the transition piece4, for example, parts which reach a high temperature with ease in particular by making the angles of inclination of the cooling holes12which are made in the inner parts of the transition piece end frame6which are located on the upper side and the lower side of the transition piece4relative to the inner circumferential surface of the transition piece end frame6different from each other in this way.

In addition, the cooling hole12which is made in the inner part of the transition piece end frame6which is located on the upper side of the transition piece4may be configured to supply the cooling air directly to the inner-circumference-side inclined part of the first-stage stator vane end wall10, and the cooling hole12which is made in the inner part of the transition piece end frame6which is located on the lower side of the transition piece4may be configured to supply the cooling air directly to an inner-circumference-side leading end of the first-stage stator vane end wall10.

Incidentally, as illustrated inFIG. 6, it is desirable to arrange the cooling holes12which are made in the inner parts of the transition piece end frame6which are located on the upper side of the transition piece4such that a ratio (an arrangement pitch thereof P/a hole diameter thereof D) of the arrangement pitch to the hole diameter of the cooling holes12which are arranged in the vicinity of the center part of the transition piece end frame6becomes smaller than a ratio (an arrangement pitch thereof P/a hole diameter thereof D) of the arrangement pitch to the hole diameter of the cooling holes12which are arranged in the vicinity of peripheral parts of the transition piece end frame6in a direction which is vertical to the combustion gas flowing direction5in the transition piece end frame6.

Likewise, it is also desirable to arrange the cooling holes12which are made in the inner parts of the transition piece end frame6which are located on the lower side of the transition piece4such that a ratio (an arrangement pitch thereof P/a hole diameter thereof D) of the arrangement pitch to the hole diameter of the cooling holes12which are arranged in the vicinity of the central part of the transition piece end frame6becomes smaller than a ratio (an arrangement pitch thereof P/a hole diameter thereof D) of the arrangement pitch to the hole diameter of the cooling holes12which are arranged in the vicinity of the peripheral parts of the transition piece end frame6in the direction which is vertical to the combustion gas flowing direction5in the transition piece end frame6.

In general, since the temperature of the vicinity of the central part of the transition piece end frame6is higher than the temperature of the vicinity of the peripheral parts of the transition piece end frame6, the amount of the cooling air which is supplied to the vicinity of the central part of the transition piece end frame6is increased by making the ratio (the arrangement pitch P/the hole diameter D) of the arrangement pitch to the hole diameter of the cooling holes12which are arranged in the vicinity of the central part of the transition piece end frame6smaller than the ratio (P/D) of the arrangement pitch P to the hole diameter D of the cooling holes12which are arranged in the vicinity of the peripheral parts of the transition piece end frame6, and thereby it becomes possible to effectively cool the vicinity of the central part of the transition piece end frame6and the first-stage stator vane end wall10which faces the transition piece end frame6.

Further, as illustrated inFIG. 6, it is more preferable to set the ratio (the arrangement pitch P/the hole diameter D) of the arrangement pitch to the hole diameter of the cooling holes12which are arranged in the vicinity of the central part of the transition piece end frame6to equal to or less than 3.1 and to set the ratio (the arrangement pitch P/the hole diameter D) of the arrangement pitch to the hole diameter of the cooling holes which are arranged in the vicinity of the peripheral parts of the transition piece end frame6to equal to or less than 4.0. Air which spouts out from the mutually adjacent cooling holes12forms a cooling film in the vicinity of the peripheral parts of the transition piece end frame6and thereby it becomes possible to surely cool the first-stage stator vane end wall10and, in addition, it becomes possible to effectively cool the vicinity of the central part of the transition piece end frame6by increasing the amount of the cooling air which is supplied to the vicinity of the central part of the transition piece end frame6by configuring in this way.

The air which spouts out from the mutually adjacent cooling holes12forms the cooling film continuously in the circumferential direction by setting the ratio (the arrangement pitch P/the diameter hole D) of the arrangement pitch of the cooling holes12to the hole diameter to equal to or less than 4.0, and consequently it becomes possible to surely cool the first-stage stator vane end wall10.

As described above, it becomes possible to minimize a distribution amount of the cooling air by respectively setting the hole diameter D and the arrangement pitch P of the cooling holes12in a plurality of ranges in accordance with the amount of the cooling air which is required for the first-stage stator vane end wall10.

Incidentally, it is not necessary to fix the ratio (the arrangement pitch P/the hole diameter D) of the arrangement pitch of the cooling holes12to the hole diameter thereof, and it is also possible to further reduce the amount of the cooling air by arranging the cooling holes12on the basis of other P/D ratios and other cooling hole diameters D in conformity to a circumferential-direction distribution of the combustion gas temperature and so forth.

Third Embodiment

A transition piece end frame structure that according to the third embodiment of the present invention will be described with reference toFIG. 7andFIG. 8.FIG. 7is a sectional diagram illustrating one example of the transition piece end frame structure in the third embodiment.FIG. 8is an arrow view (a perspective view) taken in a D-D′ direction inFIG. 7.

In the transition piece cooling holes in the third embodiment, as illustrated inFIG. 7, the cooling holes are arranged at positions which are mutually different in height measured from the inner circumference surface of the transition piece end frame6in a state of being divided into respective pluralities of holes as a plurality of cooling holes14and a plurality of cooling holes16. There are cases where a component manufacturing tolerance and minute misalignment of assembly occur between the transition piece and the first-stage stator vane end wall. Therefore, it becomes possible to supply the cooling air to a target position through the respective cooling holes14and16even in a case where the misalignment occurs.

In addition, as illustrated inFIG. 8, the plurality of cooling holes14and the plurality of cooling holes16which are disposed at positions which are mutually different in height measured from the inner circumferential surface of the transition piece end frame6are alternately arranged such that the mutually adjacent cooling holes are mutually different in height in the circumferential direction of the transition piece end frame6.

In the third embodiment, the transition piece cooling holes are configured as described above and therefore it becomes possible to evenly cool a surface of the first-stage stator vane end wall10which faces the transition piece end frame6over the entire circumference.

Fourth Embodiment

A transition piece end frame structure according to the fourth embodiment of the present invention will be described with reference toFIGS. 9 and 10.FIG. 9is a sectional diagram illustrating one example of the transition piece end frame structure in the fourth embodiment.FIG. 10is an arrow view (a perspective view) taken in an E-E′ direction of an arrow inFIG. 9.

In the transition piece cooling holes in the fourth embodiment, as illustrated inFIG. 9, the cooling holes are arranged in a state of being divided into a plurality of cooling holes18and a plurality of cooling holes20which are mutually different in inclination angle relative to the inner circumferential surface of the transition piece end frame6.

In addition, as illustrated inFIG. 10, the pluralities of the cooling holes18and20which are mutually different in inclination angle relative to the inner circumferential surface of the transition piece end frame6are alternately arranged in the circumferential direction of the transition piece end frame6such that the inclination angles of the mutually adjacent cooling holes are mutually different.

The transition piece cooling holes in the fourth embodiment are configured as described above and therefore it becomes possible to evenly cool the surface of the first-stage stator vane end wall10which faces the transition piece end frame6over the entire circumference.

Fifth Embodiment

A transition piece end frame structure according to the fifth embodiment of the present invention will be described with reference toFIGS. 11 and 12.FIG. 11is a sectional diagram illustrating one example of the transition piece end frame structure in the fifth embodiment of the present invention.FIG. 12is an arrow view (a perspective view) taken in an F-F′ direction of an arrow inFIG. 11.

In the transition piece cooling holes in the fifth embodiment of the present invention, a plurality of cooling holes22are arranged at a predetermined angle (diagonally) in a mutually separated state in the circumferential direction of the transition piece end frame6as illustrated inFIG. 12. In a case where that the metal temperature of the transition piece end frame6is high becomes a problem, it becomes possible to reduce the metal temperature of the transition piece end frame6without increasing the amount of cooling air in comparison with a structure in which the colling holes are arranged in parallel with the axial direction of the combustor.

Sixth Embodiment

A transition piece end frame structure according to the sixth embodiment of the present invention will be described with reference toFIG. 13andFIG. 14.FIG. 13is a sectional diagram illustrating one example of the transition piece end frame structure in the sixth embodiment of the present invention.FIG. 14is an arrow view (a perspective view) taken in a G-G′ direction of an arrow inFIG. 13.

In the transition piece cooling holes in the sixth embodiment, the cooling holes are configured by a first cooling hole24which communicates between an outer circumferential surface and an inner circumferential surface of the transition piece end frame6at a first angle (a predetermined angle) in the radial direction of the transition piece end frame6and a second cooling hole12which communicates between another outer circumferential surface and another inner circumferential surface of the transition piece end frame6at a second angle (which is different from the first angle) in the axial direction of the transition piece end frame6.

In addition, as illustrated inFIG. 14, the first cooling holes24and the second cooling holes12are alternately arranged in the circumferential direction of the transition piece end frame6.

Incidentally, the present invention is not limited to the abovementioned embodiments and various modified examples are included. For example, the abovementioned embodiments are described in detail for ready understanding of the present invention and are not necessarily limited to the embodiments which include all the configurations which are described above. In addition, it is possible to replace part of a configuration of one embodiment with a configuration of another embodiment, and it is also possible to add a configuration of another embodiment to a configuration of one embodiment. In addition, it is also possible to add/delete/replace another configuration to/from/with part of one configuration of each embodiment.

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