Gas turbine combustor

Background of the Invention

1. Field of the Invention

0001The present invention relates to a gas turbine combustor, more particularly to a gas turbine combustor having a structure to reduce combustion vibration, and a gas turbine generation plant using the same.

2. Description of the Related Art

0002A gas turbine plant has a compressor, a combustor and a turbine. The compressor takes in air, compresses and discharges as high-pressure compressed air. The discharged compressed air is introduced to the combustor, and fuel is combusted by using the compressed air to produce hot combustion gas. The combustion gas is introduced to the turbine to drive the turbine.

0003When the fuel is combusted, the combustion vibration sometimes occurs in the combustor. In order to stably operate the gas turbine plant, it is necessary to effectively restrain the combustion vibration of the combustor.

0004A gas turbine is disclosed in Japanese Laid Open Patent Application (<patcit id="pcit0001" dnum="JPP2002174427A"><text>JP-P2002-174427A</text></patcit>). In the gas turbine of this conventional example, a cylindrical body in which a combustion region is formed is provided and a resonator with a cavity is provided for the cylindrical body in the outer circumference. The resonator has sound absorption holes connected to the cavity.

0005Also, a resonator module to restrain combustion instability of a combustor in a gas turbine generation plant is disclosed in USP <patcit id="pcit0002" dnum="US6530221B1"><text>6,530,221 B1</text></patcit>. The resonator module of this conventional example is installed along a flow path of combustion gas downstream of the combustion zone of the combustor assembly, and contains a first member and a second member. The first member has a size smaller than the diameter of the flow path in a transition piece and has a plurality of openings connected to the flow path. The second member has substantially the same size as that of the first member. The second member is provided to cover the first member and a space is formed between the first and second members.

0006Also, a gas turbine combustor cooling structure is disclosed in Japanese Laid Open Patent Application (<patcit id="pcit0003" dnum="JPP2003214185A"><text>JP-P2003-214185A</text></patcit>). In a gas turbine combustor with the gas turbine combustor cooling structure of this conventional example, a double wall section is provided to have an outer side wall and a combustion gas side wall, between which cooling air flows. A cover is provided for the outer side wall to form a cavity. Impingement cooling holes are formed in the cover and sound absorption holes are provided for the outer side wall and the combustion gas side wall. The cooling air passages are provided to avoid the sound absorption holes.

0007A gas turbine combustor with the features of the preamble portion of claim 1 is disclosed in <patcit id="pcit0004" dnum="EP1213539A1"><text>EP 1213539 A1</text></patcit>.

Summary of the Invention

0008An object of the present invention is to provide a gas turbine combustor in which combustion vibration is restrained.

0009The present invention provides a gas turbine combustor with the features of claim 1 and a method of manufacturing a gas turbine combustor with the features of claim 23. Preferred embodiments are defined in the dependent claims.

0010In the present invention, a gas turbine combustor includes a combustion liner in which a combustion region is formed; and a housing provided for a wall of the combustion liner in a predetermined circumferential region of the combustion liner to form a resonance space between the combustion liner and the housing. The combustion region and the resonance space are connected by a plurality of combustion liner through-holes, and a circumferential length of the housing is longer than a diameter of the combustion liner.

0011Here, the distance between the wall of the combustion liner and the housing is desirably in a range of 10 mm to 30 mm, and the diameter of each of the plurality of combustion liner through-holes is desirably in a range of 1 mm to 5 mm. In addition, a percentage of a total of areas of the plurality of combustion liner through-holes to an area of the predetermined circumferential region is desirably in a range of 3 percent to 10 percent, and a thickness of the wall of the combustion liner is desirably in a range of 2 mm to 7 mm.

0012In this case, each of the side sections may include a flat plate section; and a curved section smoothly connecting the flat plate section and the upper section, such that an angle between the flat plate section and the upper section is obtuse.

0013Also, each of the side sections may be connected with the wall of the combustion liner such that an angle between the wall of the combustion liner and a surface of the side section opposite to the resonance space is obtuse. Also, a thickness of the housing is in a range of 1.6 mm to 5 mm, and a radius of curvature of the curved section is in a range of 5 mm to 20 mm.

0014Also, the resonance space may be single in an inside of the housing. Also, the housing may be single.

0015Also, the housing may be connected with an outer surface of the wall of the combustion liner, and an inner surface of the wall of the combustion liner corresponding to the housing may have a heat-resistant coating layer.

0016Also, the plurality of combustion liner through-holes may be uniformly distributed in the predetermined circumferential region. Or, the plurality of combustion liner through-holes may be ununiformly distributed in the predetermined circumferential region based on a temperature distribution in the combustion region.

0017The gas turbine combustor may further include a swirler assembly connected with the combustion liner; and a swirler assembly housing provided for a wall of the swirler assembly in a predetermined circumferential region of the swirler assembly to form a housing resonance space between the swirler assembly and the swirler assembly housing. The combustion region and the housing resonance space are connected by a plurality of swirler assembly through-holes, and a circumferential length of the swirler assembly housing is longer than a diameter of the swirler assembly.

0018In another aspect of the present invention, a gas turbine combustor includes a swirler assembly; a combustion liner connected with the swirler assembly, a combustion region being formed in the combustion liner; and a swirler assembly housing provided for a wall of the swirler assembly in a predetermined circumferential region of the swirler assembly to form a housing resonance space between the swirler assembly and the swirler assembly housing. A space in the swirler assembly and the housing resonance space are connected by a plurality of swirler assembly through-holes. A circumferential length of the swirler assembly housing is longer than a diameter of the swirler assembly.

0019Also, a distance between the wall of the swirler assembly and the swirler assembly housing is desirably in a range of 10 mm to 30 mm, and the diameter of each of the plurality of swirler assembly through-holes is desirably in a range of 1 mm to 5 mm. A percentage of a total of areas of the plurality of swirler assembly through-holes to an area of the predetermined circumferential region is desirably in a range of 3 percent to 10 percent, and a thickness of the wall of the swirler assembly is desirably in a range of 2 mm to 7 mm.

0020Also, the swirler assembly housing may include an upper section opposing to the wall of the swirler assembly; and side sections extending from the upper section and connected with the wall of the swirler assembly to form the housing resonance space. Hole may be opened in at least one of the side sections. In this case, each of the side sections may include a flat plate section; and a curved section smoothly connecting the flat plate section and the upper section, such that an angle between the flat plate section and the upper section is obtuse.

0021Also, each of the side sections may be connected with the wall of the swirler assembly such that an angle between the wall of the swirler assembly and a surface of the side section opposite to the housing resonance space is obtuse.

0022Also, the thickness of the swirler assembly housing may be in a range of 1.6 mm to 5 mm, and a radius of curvature of the curved section may be in a range of 5 mm to 20 mm.

0023Also, the housing resonance space is single in an inside of the swirler assembly housing. Also, the swirler assembly housing is single.

0024Also, the swirler assembly housing is connected with an outer surface of the wall of the swirler assembly, and an inner surface of the wall of the swirler assembly corresponding to the swirler assembly housing has a heat-resistant coating layer.

0025Also, the plurality of swirler assembly through-holes may be uniformly distributed in the predetermined circumferential region. Instead, the plurality of swirler assembly through-holes may be ununiformly distributed in the predetermined circumferential region based on a temperature distribution in the combustion region.

0026In another aspect of the present invention, a method of manufacturing a gas turbine combustor is achieved according to claim 23.

0027Also, the method of manufacturing a gas turbine combustor may be achieved by further coupling a swirler assembly housing with a second slag hole to the swirler assembly by welding; and by taking out weld slag left in the swirler assembly housing from the second slag hole. In this case, the method of manufacturing a gas turbine combustor may further include blocking the second slag hole after the taking-out step from the second slag hole.

0028In another aspect of the present invention, method of manufacturing a gas turbine combustor is achieved by providing a swirler assembly housing with a first slag hole; by coupling the swirler assembly housing to the swirler assembly by welding; and by taking-out weld slag left in the swirler assembly housing from the first slag hole. In this case, the method of manufacturing a gas turbine combustor may further include blocking the first slag hole after the taking-out step.

Brief Description of the Drawings

0029<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> shows the structure of an embodiment of a gas turbine combustor of the present invention;</li><li><figref idref="f0002">Fig. 2A</figref> is a cross sectional view of the combustor along the A-A' line of <figref idref="f0001">Fig. 1</figref>;</li><li><figref idref="f0002">Fig. 2B</figref> is a cross sectional view showing the combustor along the B-B' line of <figref idref="f0001">Fig. 1</figref>;</li><li><figref idref="f0002">Fig. 2C</figref> is a cross sectional view of a modification of the combustor of the present invention;</li><li><figref idref="f0003">Fig. 3</figref> is a broken perspective view showing the structure of an acoustic liner;</li><li><figref idref="f0004">Fig. 4</figref> is a broken perspective view showing the structure of another acoustic liner;</li><li><figref idref="f0004">Fig. 5</figref> is a cross sectional view showing the wall of the combustion liner 2 along the plane parallel to the wall;</li><li><figref idref="f0005">Fig. 6A</figref> shows the shape of the section of the acoustic liner;</li><li><figref idref="f0005">Fig. 6B</figref> shows the shape of the section of a modification of the acoustic liner;</li><li><figref idref="f0006">Fig. 6C</figref> shows the shape of the section of another modification of the acoustic liner; and</li><li><figref idref="f0007">Fig. 7</figref> is a plan view showing the shape of the acoustic liner before pressing.</li></ul>

Description of the preferred Embodiments

0030Hereinafter, a gas turbine combustor of the present invention will be described in detail with reference to the attached drawings. The gas turbine combustor of the present invention is preferably applied to a gas turbine generation plant.

0031<figref idref="f0001">Fig. 1</figref> is a cross sectional view showing the structure of the gas turbine combustor. Referring to <figref idref="f0001">Fig. 1</figref>, a gas turbine combustor 1 has a combustion liner 2. The combustion liner 2 has a cylindrical shape, and contacts a cooling air region 7. A combustion region 9 is formed inside the combustion liner 2. A premixing nozzle 4 and a pilot nozzle 6 are provided on the upstream side of the combustion liner 2. A bypass flow path 8 is provided for the combustion liner 2 to introduce air into the combustion region. 9. An air inlet 13 is provided for the combustion liner 2 to introduce a part of compressed air discharged from a compressor (not shown).

0032Many holes 14 are provided for the combustion liner 2. Housings 10a and 10b are provided for the outer circumference of the combustion liner 2 in a region where the holes 14 are provided, to form spaces in the outer surface of the combustion liner 2. Cooling holes 12 are provided for the side portion of the housings 10a and 10b. It is desirable that a lot of the cooling holes 12 are provided for the side portions of the housings 10a and 10b on the upstream side. Purge holes 22 are provided for the surfaces of the housings 10a and 10b which are opposite to the surface of the combustion liner 2. Hereinafter, a combustion vibration restraint section which is composed of the housing and the many holes 14 formed on the liner 2 and is referred to as an acoustic liner.

0033A housing 10c which does not from part of the invention, is provided for the inner circumference of the combustion liner 2 where the air inlet 13 is provided and forms a space from the inner wall of the combustion liner 2, i.e., on the side of the combustion region 9. The housing 10c has a gap 16 on the downstream side, and the inside of the housing 10c and the combustion region 9 are connected through the gap 16. It is desirable that other air inlets are provided on other positions other than the position where the housing 10c is provided. Also, the housing 10c is provided in the neighborhood of the premixing nozzle 4 but may be provided on the downstream side.

0034<figref idref="f0002">Fig. 2A</figref> is a cross sectional view of the combustor along the A-A' line of <figref idref="f0001">Fig. 1</figref>. The housing 10a is provided over the whole outer circumference of the combustion liner 2 to surround the periphery of the combustion liner 2. No partition is provided inside the housing 10a, resulting in a single space. Therefore, the manufacture of the housing 10a is easy and the housings 10a and 10b are light in weight. The combustion region 9 contains hotter regions 17 which become hotter than the other regions. The hotter region 17 is located on the downstream side of the premixing nozzle 4. The many holes 14 are provided for the wall of the combustion liner 2 in a place near the hotter region 17. The holes 14 may be provided less in the place farther from the hotter region 17 or there may be no hole 14.

0035<figref idref="f0002">Fig. 2B</figref> is a cross sectional view showing the combustor along the. B-B' line of <figref idref="f0001">Fig. 1</figref>. The housing 10b is formed to cover a portion of the outer circumference of the combustion liner 2 in angular region less than 360 degrees. Therefore, it is possible to attach the housing 10b to the combustion liner 2 to avoid interference with a structural component provided around the combustion liner 2. It is desirable that the circumferential length of the housing 10b is equal to or longer than the diameter of the combustion liner 2. In other words, it is desirable that the angle of the portion covered by the housing 10b is roughly equal to or more than 115 degrees. There is no partition in the housing 10b, to form a single space. Therefore, the manufacture of the housing 10b is easy and the housing 10b is light in weight.

0036<figref idref="f0002">Fig. 2C</figref> is a cross sectional view of a modification of the combustor of the present invention. Two housings 10d are provided on the outer circumference of the combustion liner 2 on symmetrical positions with respect to a plane passing a center axis of the combustor to cover a region larger than 115 degrees and less than 180 degrees. In the combustion region 9, there are hotter regions 17 which become hotter than the other regions. More holes 14 are provided for the wall of the combustion liner 2 in the place near hotter regions 17. Less holes 14 are provided for the wall of the combustion liner 2 in the place apart from the hotter regions 17 or no hole 14 is provided.

0037Referring to <figref idref="f0003">Fig. 3</figref>, the broken perspective view of the housing 10 (housing 10a or 10b in <figref idref="f0001">Fig. 1</figref>) is shown. The housing 10 has side sections 23 connected with the wall of the combustion liner 2 and an upper section 18 extending from the side section 23 to oppose to the wall of the combustion liner 2. The side section 23 has a flat plate section 20 coupled to the combustion liner 2 and a curved section 21 connecting the plate section 20 and the upper section 18. The purge holes 22 are provided for the upper section 18. The cooling holes 12 are provided for the plate section 20. No purge hole and no cooling hole may be provided. A heat-resistant coating 19 is applied to the inner surface of the combustion liner 2 on the side the combustion region 9 in the region in which the housing 10 is provided. The material of heat-resistant coating 19 is such as ceramic, alumina, and yttrium alloy. The heat-resistance of the wall for which the many holes 14 are provided is enhanced by such a heat-resistant coating 19. The radius of curvature of the curved section 21 is as large as about 10 mm. Because the curvature is large, the stress is small in the corner portion. The upper section 18 opposes to the wall of the combustion liner 2 in parallel. The angle between the upper section 18 and the plate section 20 is as obtuse as about 100 degrees. Therefore, the stress becomes smaller in the corner. The housing 10 is produced through a press process. The upper section 18 has the shape that the central region far from the curved section 21 is hollow rather than the region near the curved section 21. This hollow shape is obtained generally in the bottom of a product produced through the press process. As shown in <figref idref="f0003">Fig. 3</figref>, cooling paths 26 are provided in the combustion liner 2 for cooling medium.

0038<figref idref="f0004">Fig. 4</figref> is a broken perspective view showing the housing 10c. Holes of the air inlet 13 are provided for the wall of the combustion liner 2 in the region for which the housing 10c is provided. Many holes 15 are provided for the upper section 18c of the housing 10c. The gap 16 is provided between the upper section 18c and the inner wall of the combustion liner 2 in the end of the housing 10c on the downstream side. The cooling paths 26 are provided inside the wall of the combustion liner 2 in the axial direction of the combustion liner 2, similar to <figref idref="f0003">Fig. 3</figref>.

0039<figref idref="f0004">Fig. 5</figref> is a cross sectional view showing the wall of the combustion liner 2 in the neighborhood where the housing 10 is provided, along the plane parallel to the wall. The plurality of cooling paths 26 are provided inside the wall in parallel and the holes 14 are provided between the cooling paths 26.

0040<figref idref="f0005">Fig. 6A</figref> shows the shape of the section of the acoustic liner. The housing 10 has the side sections 23 connected to the combustion liner 2 and the upper section 18 extending from the side sections 23 to oppose to the wall of the combustion liner 2. The upper section 18 is perpendicular to the direction of the diameter of the combustion liner 2, as described with reference to <figref idref="f0003">Fig. 3</figref>.

0041<figref idref="f0005">Fig. 6B</figref> shows the shape of the section of a modification of the acoustic liner. When a housing 10e is cut in an axial direction of the combustion liner 2, the housing 10e is composed of an upper section 18e of a semi-elliptical form along the major axis. The housing 10e is desirable in that the stress is less.

0042<figref idref="f0006">Fig. 6C</figref> shows a cross section of the acoustic liner in another modification of the embodiment. In a housing 10f, the upper section 18 of the housing 10f shown in <figref idref="f0003">Fig. 3</figref> is replaced by an upper section 18f having a convex shape in the direction apart from the wall of the combustion liner 2. Such a housing 10f is desirable in that the stress in the curved section 21e is less, resulting in high strength.

0043The characteristic of the acoustic liner can be thought as a simple vibration model that the space in the housing functions as a spring, a fluid particle in the through-hole functions as a mass and the fluid resistance in the through-hole functions as attenuation. It is necessary to determine the size of the space in the housing, the through-hole diameter, a pitch between the holes, and the thickness of the wall of the combustion liner in accordance with the frequency and magnitude of the combustion vibration to be restrained.

0044The inventors achieved a desirable sound absorption characteristic of the acoustic liner designed as follows. <ol id="ol0001" compact="compact"><li>(1) The distance between the wall of the combustion liner 2 and the upper section 18 of the housing 10 is in a range of 10 mm to 30 mm.</li><li>(2) A percentage of a total of areas of the holes 14 to the region where the holes 14 are provided (that is, the region which is covered with the housing 10) is in a range of 3 % to 10 %.</li><li>(3) The thickness of the wall of the combustion liner 2 is in a range 2 mm to 7 mm. The characteristic of the acoustic liner is determined in relation to these values. Therefore, the combustor which is manufactured to meet the above conditions (1) to (3) at the same time represents an exceptional multiplying effect. The acoustic liner has the dual structure of the wall of the combustion liner 2 and the housing 10. The balance between the wall of the combustion liner 2 and the housing 10 is important from the viewpoint of the strength of the structure. The inventors achieved the combustor which has desirable strength with the acoustic liner designed as follows. </li><li>(4) The thickness of the wall of the combustion liner 2 is in a range of 2 mm to 7 mm.</li><li>(5) The thickness of the housing 10 is in a range of 1.6 mm to 5 mm.</li><li>(6) The radius of curvature of the curved section 21 coupling the upper section 18 of the housing 10 and the plate section 20 is in a range of 5 mm to 20 mm.</li><li>(7) The side section 23 is inclined in an angle between 0 degree and 20 degrees from a direction perpendicular to the wall of combustion liner 2 (that is, an angle between the plane of the side section 23 contacting the cooling air and a plane of the wall of the combustion liner 2 is less than 110 degrees).</li></ol>

0045The strength of the acoustic liner is determined in relation to these values. Therefore, the combustor which is manufactured to meet the above conditions (4) to (7) at the same time represents an exceptional multiplying effect. Moreover, if the above combustor is further composed of cooling paths 26, high strength is achieved.

0046Moreover, the acoustic liner of the present invention has high strength since there is little weld section in the liner, compared with the structure in which a lot of small acoustic liners (the maximum circumferential length is smaller than the diameter of the combustion liner) are provided or the structure which partitions are provided inside the housing.

0047When the structure has the partitions, the structure meeting the conditions (1) to (3) and the structure meeting the conditions (4) to (7) at the same time, the combustor has the exceptional multiplying effect to achieve the restraint of the combustion vibration and extreme high strength at the same time.

0048<figref idref="f0007">Fig. 7</figref> shows a metal plate 27 before being pressed to the housing 10b. The metal plate 27 is composed of a rectangular body section 28. The cooling holes 12 and the purge holes 22 are formed in the body section 28. Semicircular sections 30 are coupled to the both ends of the body section 28 in the longitudinal direction by welding sections 32. A slag pulling-out hole 34 which is enough to take away weld slag is provided for the end 30. The hole 34 may be provided for both of the ends 30. The metal plate 27 is pressed and welded to the wall of the combustion liner 2. Thus, the housing 10 is formed to have the section shape shown in <figref idref="f0003">Fig. 3</figref>. The weld slag generated in the welding is removed from the slag pulling-out hole 34. In case that it is desirable that the slag pulling-out hole 34 does not exist, the hole 34 is covered by the welding. By forming the slag pulling-out hole 34, the influence of the remaining slag on the characteristic of the housing 10 is reduced.

0049When the acoustic liner of the present invention is attached to the swirler assembly and transition piece of the gas turbine combustor in addition to the combustion liner, the similar effect to the above can be achieved.

0050The combustor 1 having the above-mentioned structure operates as follows.

0051When the gas turbine system which contains the combustor 1 is operated, cooling air 11 compressed by a compressor (not shown) flows into the housing 10c through an air inlet 13. Fuel and air are supplied from the premixing nozzle 4 and the pilot nozzle 6. The supplied fuel is ignited by an igniter (not shown) and the combustion region 9 is filled with the flame and hot combustion gas. The hot combustion gas flows out from the transition piece on the downstream side and is supplied to the gas turbine (not shown).

0052The cooling air 11 is blown out from the gap 16 of the housing 10c. The cooling air 11 flows along the wall of the combustion liner 2 to cool the wall. The cooling air 11 or steam flows through the cooling paths 26. Thus, the wall of the combustion liner 2 is effectively cooled.

0053Combustion vibration is caused in the frequency peculiar to the combustion liner 2 through combustion in the combustion region 9. The combustion gas vibrates intensely in holes 14 and 15. The vibration attenuates due to friction of the combustion gas and the wall of the holes 14 and 15. That is, supposing that the housing 10 is a spring, the holes 14 and 15 function as a damper to convert the vibration of the spring into heat so as to attenuate the vibration of the spring. As a result, the combustion vibration of the combustor 1 is restrained.

0054In the region in which the housing 10 is provided, the more holes 14 are provided for the hotter regions 17. In this case, convection generated due to the hotter regions 17 and a lower temperature region can be restrained in the housing 10. Therefore, the flow of combustion gas in the combustion region 9 into the inside of the housing 10 is restrained.

0055The purge air flows into the housing 10 through the purge holes 22. The pressure in the housing 10 becomes high because of the purge air and the flow of the combustion gas into the inside of the housing 10 is restrained in the combustion region 9. The cooling air 11 flows into the housing 10 through the cooling hole 12. The cooling air 11 cools the wall of the combustion liner 2. Therefore, the wall can be effectively cooled although the wall portion where the holes 14 are formed so that the strength is weaker than the other portion. Because the cooling holes 12 are provided for the plate section 20 nearer the wall of the combustion liner 2 than the purge holes 22, the cooling air 11 flowing through the cooling holes 12 cools the wall of the combustion liner 2 effectively.

0056Conventionally, the inside of the housing 10 is often partitioned into small rooms. When there is no partition, the sound absorption efficiency of the acoustic liner (the efficiency to absorb acoustic energy of the combustion vibration inputted to the acoustic liner) decreases depending on the incident angle of the sound wave inputted from the inside of the combustor to the acoustic liner. From the above reason, the partition is often adopted. However, no partition is provided for the inside of the housing 10 of the present invention.

0057The inventors of the present invention discovered the following fact through calculation of a resonance mode in the combustion liner 2 and the sound absorption characteristic of the acoustic liner. That is, the discovered fact is that even if there was not an acoustic liner, the large combustion vibration does not occur under the condition of the incident angle of the sound wave that the sound absorption efficiency of the acoustic liner is degraded exceedingly. Therefore, it is concluded that it is not necessary to provide any partition in the housing.

0058In the above-mentioned calculation, the conditions are adopted that the section of the combustion liner 2 is circular and the housing 10 covers a considerable circumferential part of the wall of the combustion liner 2, e.g., a circumferential portion longer than the diameter of the combustion liner. In the above-mentioned calculation, as an example when the inside of the housing is partitioned by many partitions, it is considered that the inside of the housing is divided into many small rooms and the a total of circumferential lengths of the small rooms covering the combustion liner is as small as ignorable, compared with the diameter of the combustion liner 2.

0059The housing 10 of the present invention can achieve the sound absorption efficiency equivalent to that of the housing in which many partitions are provided, without any partition, based on the above-mentioned calculation. Such a housing 10 is light because no partition is provided. The manufacture of the housing 10 is easy and the manufacturing cost can be reduced.

0060According to the present invention, the combustor for the gas turbine is provided which has a combustion vibration restraint section with high heat resistance. Moreover, the combustion vibration restraint section is light and simple in the structure.