Patent Publication Number: US-11022304-B2

Title: Combustor, gas turbine provided with same, and method of repairing combustor

Description:
TECHNICAL FIELD 
     The present invention relates to a combustor having a sound attenuator installed at an outer peripheral side of a cylinder in which a combustion gas flows through an inner peripheral side thereof, a gas turbine including the same, and a method of repairing a combustor. Priority is claimed on Japanese Patent Application No. 2014-073550, filed Mar. 31, 2014, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     A gas turbine includes a compressor configured to compress air, a combustor configured to combust fuel in the air compressed by the compressor to generate a combustion gas, and a turbine configured to be driven by the combustion gas from the combustor. 
     For example, as disclosed in the following Patent Literature 1, the combustor of the gas turbine has a combustion liner (or a transition piece) in which a fuel is combusted, an injector configured to inject the fuel and air into the combustion liner, and a sound attenuator such as a sound damper installed at an outer peripheral side of the combustion liner. A large number of small through-holes passing from the inner peripheral side to the outer peripheral side are formed in the combustion liner. The sound attenuator has a cover configured to cover a portion of the outer periphery of the combustion liner in which the large number of through-holes are formed, and plates configured to partition a space between the combustion liner and the cover into a plurality of spaces. 
     In the combustion liner, the fuel is combusted at the inner peripheral side, and the combustion gas having a high temperature generated by the combustion flows therein. For this reason, the combustion liner is formed of a metal plate having a high thermal resistance. Further, a thermal barrier coating is applied to a surface of the metal plate. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1 
     Japanese Unexamined Patent Application, First Publication No. 2013-117231 
     SUMMARY OF INVENTION 
     Technical Problem 
     When the combustor disclosed in Patent Literature 1 is repaired, it is often the case that, after the thermal barrier coating that has deteriorated or been damaged due to heat is delaminated, the thermal barrier coating is applied to the inner peripheral side of the combustion liner again. In the process of delaminating the thermal barrier coating, particles of metal, ceramics, or the like that form the thermal barrier coating enter the cover via the large number of through-holes of the combustion liner. In addition, even in the process of applying the thermal barrier coating, the particles of the metal, ceramics, or the like that form the thermal barrier coating enter the cover via the large number of through-holes of the combustion liner. Further, even in an operation of the combustor, various kinds of foreign substances enter the cover via the large number of through-holes of the combustion liner. 
     The various kinds of foreign substances that have entered the cover as described above are preferably removed in a process of repairing the combustor. However, removal of the foreign substances that have entered the cover via the large number of small through-holes formed in the combustion liner is extremely difficult. For this reason, development of a method of easily removing foreign substances from the inside of the cover in the process of repairing the combustor is required. 
     Here, the present invention is directed to providing a combustor that allows easy removal of foreign substances from the inside of the sound attenuator, a gas turbine including the same, and a method of repairing a combustor. 
     Solution to Problem 
     In order to achieve the aforementioned objects, there is provided a method of repairing a combustor according to an aspect of the present invention, the combustor including a cylinder in which a combustion gas flows through an inner peripheral side and a plurality of holes are formed so as to pass from the inner peripheral side to an outer peripheral side, and a sound attenuator having a space-forming member configured to form a space connected to the plurality of holes at the outer peripheral side of the cylinder, the method of repairing the combustor including: an opening step of opening a portion of the space-forming member in contact with an outside and bringing the outside and the space in communication with each other; a cylinder repair step of repairing the cylinder; a foreign substance removal step of removing foreign substances in the space from the opening opened in the opening step to the outside, after the cylinder repair step; and a closing step of closing the opening using a lid, after the foreign substance removal step. 
     In the repair method, since the portion of the space-forming member in contact with the outside is opened, the foreign substances in the space can be easily removed from the opening to the outside. 
     Here, in the method of repairing the combustor, in the opening step, the portion of the space-forming member in contact with the outside may be opened so as to have an opening area larger than an opening area of each of the plurality of holes. 
     In addition, in the method of repairing the combustor of any one of the above-described aspects, the space-forming member may have a pair of first plates opposite to each other at an interval, and a second plate configured to connect ends of the pair of first plates to each other, and in the opening step, the second plate may be opened from one first plate of the pair of first plates to the other first plate. 
     In addition, in the method of repairing the combustor of any one of the above-described aspects, the sound attenuator may have a porous body disposed in the space, and the method of repairing the combustor may include: a porous body extraction step of extracting the porous body in the space from the opening opened in the opening step to the outside, before the cylinder repair step; and a porous body disposition step of inserting the porous body into the space from the opening before the opening is closed in the closing step, after the foreign substance removal step. 
     In the repair method, since the porous body in the space is extracted from the opening to the outside before the cylinder repair step, the foreign substances such as metal powder generated in a process of executing the cylinder repair step can be prevented from being attached to the porous body. In addition, as the porous body is extracted from the space, movement of the foreign substances in the space becomes easy, and the foreign substances in the space can be more easily removed to the outside. 
     In addition, in the method of repairing the combustor of any one of the above-described aspects, the space-forming member may have a main body having an opening configured to bring the outside and the space in communication with each other, and a lid joined to the main body and configured to close the opening, and in the opening step, the main body and the lid may be separated from each other. 
     In the repair method, since the opening formed in the main body is opened when the main body and the lid of the space-forming member are separated from each other, the opening can be easily formed in the space-forming member. 
     In addition, in the method of repairing the combustor of any one of the above-described aspects, the space-forming member may have a main body having an opening configured to bring the outside and the space in communication with each other, and a lid joined to the main body and configured to close the opening; the sound attenuator may have a porous body disposed in the space and joined to the lid; in the opening step, the main body and the lid may be separated from each other, the lid may be distanced from the main body, and the porous body in the space may be extracted from the opening to the outside; and in the closing step, as the opening is closed by the lid, the porous body joined to the lid may be disposed in the space. 
     In the repair method, since the porous body in the space is extracted from the opening to the outside before the cylinder repair step, the foreign substances such as metal powder generated in the process of executing the cylinder repair step can be prevented from being attached to the porous body. In addition, as the porous body is extracted from the space, movement of the foreign substances in the space becomes easy, and the foreign substances in the space can be more easily removed to the outside. Moreover, in the repair method, since the porous body is joined to the lid, in the opening step, when the main body and the lid are separated from each other, the porous body in the space can be easily extracted from the opening to the outside. In addition, in the repair method, since the porous body joined to the lid is disposed in the space as the opening is closed by the lid, the porous body can be easily disposed in the space. 
     In order to accomplish the aforementioned objects, according to an aspect of the present invention, there is provided a combustor including: a cylinder in which a combustion gas flows through an inner peripheral side and a plurality of holes are formed so as to pass from the inner peripheral side to an outer peripheral side; and a sound attenuator having a space-forming member configured to form a space connected to the holes at the outer peripheral side of the cylinder, wherein the space-forming member has a main body having an opening configured to bring an outside and the space in communication with each other, and a lid joined to the main body and configured to close the opening. 
     In the combustor, since the opening formed in the main body is opened when the main body and the lid of the space-forming member are separated from each other, the opening can be easily formed in the space-forming member. Further, the foreign substances in the space can be easily removed from the opening to the outside. 
     In addition, in the combustor, an area of the opening may be larger than an opening area of each of the plurality of holes. 
     In addition, in the combustor of any one of the above-described aspects, the space-forming member may have a pair of first plates that are opposite to each other at an interval, and a second plate having the opening and configured to connect ends of the pair of first plates to each other, and the opening formed in the second plate may be opened from one first plate of the pair of first plates to the other first plate. 
     In addition, in the combustor of any one of the above-described aspects, the sound attenuator may have a porous body disposed in the space. 
     In addition, in the combustor having the porous body, the porous body may be joined to the lid. 
     In the combustor, as the lid is separated from the main body of the space-forming member, the porous body in the space can be easily extracted from the opening to the outside. In addition, in the combustor, since the porous body joined to the lid is disposed in the space as the opening is closed by the lid, the porous body can be easily disposed in the space. 
     In addition, in the combustor of any one of the above-described aspects, the sound attenuator may have a porous body disposed in the space; the space-forming member may have a pair of first plates that are opposite to each other at an interval, and a second plate having the opening and configured to connect ends of the pair of first plates to each other; the opening formed in the second plate may be opened from one first plate of the pair of first plates to the other first plate; and the porous body may come in contact with the one first plate and the other first plate of the pair of first plates and may be joined to the lid. 
     In order to accomplish the aforementioned objects, according to an aspect of the present invention, there is provided a gas turbine including: the combustor according to any one of the above-described aspects; and a turbine driven by the combustion gas from the combustor. 
     Advantageous Effects of Invention 
     According to an aspect of the present invention, foreign substances can be easily removed from the inside of the sound attenuator of the combustor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cutout side view of a major part of a gas turbine according to an embodiment of the present invention. 
         FIG. 2  is a general side view of a combustor according to the embodiment of the present invention, a major part of which is cut out. 
         FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 2 . 
         FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 3 . 
         FIG. 5  is an enlarged view of a major part of  FIG. 4 . 
         FIG. 6  is a cutout perspective view (the 1st) of a major part of a sound attenuator according to the embodiment of the present invention. 
         FIG. 7  is a cross-sectional view taken along line VII-VII of  FIG. 3 . 
         FIG. 8  is a cutout perspective view (the 2nd) of the major part of the sound attenuator according to the embodiment of the present invention. 
         FIG. 9  is a flowchart showing a procedure of a method of repairing a combustor according to an embodiment of the present invention. 
         FIG. 10  is an enlarged cross-sectional view of a major part of the sound attenuator in an opening step according to the embodiment of the present invention. 
         FIG. 11  is an enlarged cross-sectional view of the major part of the sound attenuator in a foreign substance removal step according to the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of a combustor according to the present invention, a gas turbine including the same, and a method of repairing a combustor will be described in detail with reference to the accompanying drawings. 
     As shown in  FIG. 1 , a gas turbine of the embodiment includes a compressor  1  configured to compress air, a plurality of combustors  10  configured to combust fuel in the air from the compressor  1  to generate a combustion gas, and a turbine  5  driven by the combustion gas. 
     The compressor  1  has a compressor rotor  2  configured to rotate about an axis of rotation Ar, and a compressor casing  3  configured to rotatably cover the compressor rotor  2 . The turbine  5  includes a turbine rotor  6  configured to rotate about the axis of rotation Ar, and a turbine casing  7  configured to rotatably cover the turbine rotor  6 . The compressor rotor  2  and the turbine rotor  6  are connected to each other to be integrally rotated, and form a gas turbine rotor. The combustor  10  is fixed to the turbine casing  7 . 
     As shown in  FIG. 2 , the combustor  10  includes an external cylinder  11  fixed to the turbine casing  7 , a combustion liner (or a transition piece)  12  disposed inside the turbine casing  7  and configured to send a combustion gas G having a high temperature and a high pressure to a gas flow path  9  of the turbine  5 , a fuel supply device  15  configured to supply fuel and air into the combustion liner  12 , and a sound attenuator  20  installed at an outer peripheral side of the combustion liner  12 . 
     The fuel supply device  15  has a combustor basket  16 , a pilot nozzle  17  disposed on a central axis of the combustor basket  16 , a plurality of main nozzles  18  disposed around the pilot nozzle  17  at equal intervals in a circumferential direction, and a nozzle mount  19  to which the pilot nozzle  17  and the plurality of main nozzles  18  are attached. 
     The combustion liner  12  is a cylindrical member, both ends of which are open. A portion of the combustor basket  16  is inserted inside one opening  13   a  of the combustion liner  12 . In addition, the other opening  13   b  of the combustion liner  12  is connected to the gas flow path  9  of the turbine  5 . 
     The combustion liner  12  has a base member obtained by forming a plate member in a cylindrical shape. A thermal barrier coating is applied to an inner peripheral surface of the cylindrical base member. The base member is formed of, for example, a Ni-based alloy, a Co-based alloy, or the like, having a high thermal resistance. The thermal barrier coating is formed on an inner peripheral surface of the cylindrical base member by spraying, for example, a metal powder or ceramic powder having a high thermal resistance. 
     Here, the side of the one opening  13   a  of the openings  13   a  and  13   b  at both ends of the combustion liner  12  is referred to as an upstream side, and the side of the other opening  13   b  is referred to as a downstream side. In addition, an imaginary line that connects the center of gravity of the opening surface at the upstream side of the combustion liner  12  and the center of gravity of the opening surface at the downstream side of the combustion liner  12  is referred to as an axis Ac, a direction in which the axis Ac extends is referred to as an axial direction (or an upstream/downstream direction) Da, a circumferential direction with reference to the axis Ac is simply referred to as a circumferential direction Dc, and a radial direction with reference to the axis Ac is simply referred to as a radial direction Dr. 
     The nozzle mount  19  is fixed to the furthest upstream position of the external cylinder  11 . A base end portion at the upstream side of each of the nozzles  17  and  18  is fixed to the nozzle mount  19 . The pilot nozzle  17  sprays a pilot fuel Fp downstream from a distal end portion which is a portion at the downstream side. The pilot fuel Fp forms a diffusion flame by combustion. In addition, the plurality of main nozzles  18  spray a main fuel Fm. The main fuel Fm is mixed with air A flowing downstream around the main nozzle  18  and becomes a part of the premixed gas. The main fuel Fm in the premixed gas forms a premixed flame by combustion. 
     As shown in  FIGS. 4 and 6 to 8 , a large number of small through-holes  14  passing from the inner peripheral side to the outer peripheral side are formed in the combustion liner  12 . As shown in  FIGS. 3, 4 and 6 to 8 , the sound attenuator  20  has a space-forming member  21  that forms a space S connected to the large number of through-holes  14  at the outer peripheral side of the combustion liner  12 , and a porous body  25  disposed in the space S. 
     The space-forming member  21  has a main body  22  having a discharge opening  23  configured to bring the outside in communication with the space S, and a lid  24  configured to close the discharge opening  23 . The porous body  25  is formed of, for example, a foamed metal. The porous body  25  is joined to the lid  24  by, for example, brazing. A small drain hole (not shown) configured to bring the internal space S in communication with the outside is formed in the main body  22 . The drain hole is formed to discharge drain formed by condensation of the combustion gas flowing into the internal space S via the through-hole  14  of the combustion liner  12  to the outside. The main body  22  has a first space-forming member  31  that forms a first space S 1  along the outer periphery of the combustion liner  12  in cooperation with the combustion liner  12 , a second space-forming member  32  that forms a second space S 2  at the outer peripheral side of the first space S 1  in cooperation with the first space-forming member  31 , a third space-forming member  33  that forms a third space S 3  at the outer peripheral side of the second space S 2  in cooperation with the second space-forming member  32 , and a fourth space-forming member  34  that forms a fourth space S 4  at the outer peripheral side of the third space S 3  in cooperation with the third space-forming member  33 . 
     The first space S 1  is formed along the entire outer periphery of a portion in the axial direction Da of the combustion liner  12  by the first space-forming member  31 . As shown in  FIGS. 3, 4 and 6 , the first space-forming member  31  has an upstream side plate  31   a  and a downstream side plate  31   b  that are opposite to each other in the axial direction Da, and a cylinder-opposing plate  31   c  opposite to the combustion liner  12  and configured to connect an outside end in the radial direction of the upstream side plate  31   a  and an outside end in the radial direction of the downstream side plate  31   b . Two first openings  31 Ao and  31 Bo (see  FIG. 3 ) passing from the inner peripheral side to the outer peripheral side are formed in the cylinder-opposing plate  31   c  of the first space-forming member  31 . The first space-forming member  31  is joined to the outer peripheral surface of the combustion liner  12  by, for example, brazing or the like. Alternatively, joining of the first space-forming member  31  to the combustion liner  12  may be by welding or the like. 
     The second space S 2  is constituted by a second A space S 2   a  in communication with the first space S 1  via one first A opening  31 Ao of the two first openings  31 Ao and  31 Bo (see  FIG. 3 ) formed in the cylinder-opposing plate  31   c  of the first space-forming member  31 , and a second B space S 2   b  in communication with the first space S 1  via the other first B opening  31 Bo of the two first openings  31 Ao and  31 Bo. The second A space S 2   a  expands from the first A opening  3  lAo toward one side in the circumferential direction Dc and the second B space S 2   b  expands from the first B opening  31 Bo toward the other side in the circumferential direction Dc. As shown in  FIGS. 4 and 6 , the second A space S 2   a  is constituted by a second A space-forming member  32 A and the cylinder-opposing plate  31   c  of the first space-forming member  31 . In addition, as shown in  FIGS. 7 and 8 , the second B space S 2   b  is constituted by a second B space-forming member  32 B and the cylinder-opposing plate  31   c  of the first space-forming member  31 . 
     The above-mentioned second space-forming member  32  has the second A space-forming member  32 A and the second B space-forming member  32 B. Each of the second A space-forming member  32 A and the second B space-forming member  32 B has an upstream side plate  32   a  and a downstream side plate  32   b  that are opposite to each other in the axial direction Da, and a cylinder-opposing plate  32   c  opposite to the combustion liner  12  and configured to connect an outside end in the radial direction of the upstream side plate  32   a  and an outside end in the radial direction of the downstream side plate  32   b . Further, each of the second A space-forming member  32 A and the second B space-forming member  32 B has peripheral end plates  32   d  (see  FIG. 3 ) disposed at both ends in the circumferential direction Dc of the upstream side plate  32   a  and the downstream side plate  32   b  and configured to connect ends in the circumferential direction Dc of the upstream side plate  32   a  and the downstream side plate  32   b . A second A opening  32 Ao (see  FIG. 3 ) passing from the inner peripheral side to the outer peripheral side is formed in the cylinder-opposing plate  32   c  of the second A space-forming member  32 A at a position farthest from the first A opening  31 Ao in the circumferential direction Dc. In addition, a second B opening  32 Bo (see  FIG. 3 ) passing from the inner peripheral side to the outer peripheral side is formed in the cylinder-opposing plate  32   c  of the second B space-forming member  32 B at a position farthest from the first B opening  31 Bo in the circumferential direction Dc. 
     The third space S 3  is constituted by a third A space S 3   a  in communication with the second A space S 2   a  via the second A opening  32 Ao, and a third B space Sib in communication with the second B space S 2   b  via the second B opening  32 Bo. The third B space S 3   b  expands from the second B opening  32 Bo toward one side in the circumferential direction Dc and the third A space S 3   a  expands from the second A opening  32 Ao toward the other side in the circumferential direction Dc. The third A space S 3   a  is formed by a third A space-forming member  33 A and the cylinder-opposing plate  32   c  of the second A space-forming member  32 A. The third B space S 3   b  is formed by a third B space-forming member  33 B and the cylinder-opposing plate  32   c  of the second B space-forming member  32 B. 
     The above-mentioned third space-forming member  33  has the third A space-forming member  33 A and the third B space-forming member  33 B. Each of the third A space-forming member  33 A and the third B space-forming member  33 B has an upstream side plate  33   a  and a downstream side plate  33   b  that are opposite to each other in the axial direction Da, and a cylinder-opposing plate  33   c  opposite to the combustion liner  12  and configured to connect an outside end in the radial direction of the upstream side plate  33   a  and an outside end in the radial direction of the downstream side plate  33   b . Further, each of the third A space-forming member  33 A and the third B space-forming member  33 B has peripheral end plates  33   d  (see  FIG. 3 ) disposed at both ends in the circumferential direction Dc of the upstream side plate  33   a  and the downstream side plate  33   b  and configured to connect ends in the circumferential direction Dc of the upstream side plate  33   a  and the downstream side plate  33   b  to each other. A third A opening  33 Ao (see  FIG. 3 ) passing from the inner peripheral side to the outer peripheral side is formed in the cylinder-opposing plate  33   c  of the third A space-forming member  33 A at a position farthest from the second A opening  32 Ao in the circumferential direction Dc. In addition, a third B opening  33 Bo (see  FIG. 3 ) passing from the inner peripheral side to the outer peripheral side is formed in the cylinder-opposing plate  33   c  of the third B space-forming member  33 B at a position farthest from the second B opening  32 Bo in the circumferential direction Dc. 
     The fourth space S 4  is constituted by a fourth A space S 4   a  in communication with the third A space S 3   a  via the third A opening  33 Ao, and a fourth B space S 4   b  in communication with the third B space S 3   b  via the third B opening  33 Bo. The fourth A space S 4   a  expands from the third A opening  33 Ao toward one side in the circumferential direction Dc and the fourth B space S 4   b  expands from the third B opening  33 Bo toward the other side in the circumferential direction Dc. The fourth A space S 4   a  is formed by a fourth A space-forming member  34 A and the cylinder-opposing plate  33   c  of the third A space-forming member  33 A. The fourth B space S 4   b  is formed by a fourth B space-forming member  34 B and the cylinder-opposing plate  33   c  of the third B space-forming member  33 B. 
     The above-mentioned fourth space-forming member  34  has the fourth A space-forming member  34 A and the fourth B space-forming member  34 B. Each of the fourth A space-forming member  34 A and the fourth B space-forming member  34 B has an upstream side plate  34   a  and a downstream side plate  34   b  that are opposite to each other in the axial direction Da, and a cylinder-opposing plate  34   c  opposite to the combustion liner  12  and configured to connect an outside end in the radial direction of the upstream side plate  34   a  and an outside end in the radial direction of the downstream side plate  34   b . Further, each of the fourth A space-forming member  34 A and the fourth B space-forming member  34 B has peripheral end plates  34   d  disposed at both ends in the circumferential direction Dc of the upstream side plate  34   a , the downstream side plate  34   b  and the cylinder-opposing plate  34   c  and configured to connect ends in the circumferential direction Dc of the upstream side plate  34   a , the downstream side plate  34   b  and the cylinder-opposing plate  34   c  to each other. 
     As shown in  FIG. 3 , the porous body  25  is constituted by an A porous body  25   a  disposed in the third A space S 3   a  and a B porous body  25   b  disposed in the fourth B space S 4   b . The A porous body  25   a  is disposed in the third A space S 3   a  such that the third A space S 3   a  is partitioned in the circumferential direction Dc. In addition, the B porous body  25   b  is disposed in the fourth B space S 4   b  such that the fourth B space S 4   b  is partitioned in the circumferential direction Dc. 
     As shown in  FIGS. 4 to 6 , an A discharge opening  23   a  configured to bring the outside in communication with the third A space S 3   a  is formed in the upstream side plate  33   a  of the third A space-forming member  33 A. The A discharge opening  23   a  has an opening area formed in a rectangular shape and having a larger size than an opening area of the drain hole (not shown) or the through-hole  14  of the combustion liner  12 . A pair of sides that are opposite to each other in the A discharge opening  23   a  having a rectangular shape are opposite to each other in the radial direction Dr, and the other pair of sides that are opposite to each other are opposite to each other in the circumferential direction Dc. An interval of the pair of sides that are opposite to each other in the radial direction Dr is substantially equal to an interval between the cylinder-opposing plate  32   c  of the second A space-forming member  32 A and the cylinder-opposing plate  33   c  of the third A space-forming member  33 A. That is, the A discharge opening  23   a  formed in the upstream side plate  33   a  is substantially opened from the one cylinder-opposing plate  32   c  to the other cylinder-opposing plate  33   c  of the cylinder-opposing plate  32   c  of the second A space-forming member  32 A and the cylinder-opposing plate  33   c  of the third A space-forming member  33 A that are opposite to each other. The A discharge opening  23   a  is closed by an A lid  24   a  corresponding to a shape and a size of the A discharge opening  23   a . The A lid  24   a  is joined to a portion of the space-forming member  21  around the A discharge opening  23   a  by welding. 
     The A porous body  25   a  is joined to the A lid  24   a  by brazing or the like. As shown in  FIG. 6 , the A porous body  25   a  is formed in a rectangular parallelepiped shape. The A lid  24   a  is joined to one surface  26   a  of a pair of surfaces  26   a  and  26   b  of the A porous body  25   a  having the rectangular parallelepiped shape by brazing or the like. A shape and a size of the one surface  26   a  correspond to a shape and a size of a surface of the A lid  24   a  to which the A porous body  25   a  is joined. The other surface  26   b  of the pair of surfaces  26   a  and  26   b  of the A porous body  25   a  comes in contact with the downstream side plate  33   b  of the third A space-forming member  33 A or is adjacent to the downstream side plate  33   b . One surface  26   c  of another pair of surfaces  26   c  and  26   d  of the A porous body  25   a  having the rectangular parallelepiped shape comes in contact with the cylinder-opposing plate  32   c  of the second A space-forming member  32 A or is adjacent to the cylinder-opposing plate  32   c . In addition, of the other pair of surfaces  26   c  and  26   d , the other surface  26   d  comes in contact with the cylinder-opposing plate  33   c  of the third A space-forming member  33 A or is adjacent to the cylinder-opposing plate  33   c.    
     As shown in  FIGS. 7 and 8 , a B discharge opening  23   b  configured to bring the outside in communication with the fourth B space S 4   b  is formed in the cylinder-opposing plate  34   c  of the fourth B space-forming member  34 B. The B discharge opening  23   b  is also an opening area formed in a rectangular shape and having a larger size than the opening area of the drain hole (not shown) or the through-hole  14  of the combustion liner  12 . A pair of sides that are opposite to each other in the B discharge opening  23   b  having the rectangular shape are opposite to each other in the axial direction Da, and the other pair of sides that are opposite to each other are opposite to each other in the circumferential direction Dc. An interval of the pair of sides that are opposite to each other in the axial direction Da is substantially equal to an interval between the upstream side plate  34   a  and the downstream side plate  34   b  of the fourth B space-forming member  34 B. That is, the B discharge opening  23   b  formed in the cylinder-opposing plate  34   c  is substantially opened from the upstream side plate  34   a  to the downstream side plate  34   b  of the upstream side plate  34   a  and the downstream side plate  34   b  that are opposite to each other. The B discharge opening  23   b  is closed by a B lid  24   b  corresponding to a shape and a size of the B discharge opening  23   b . The B lid  24   b  is joined to a portion of the fourth B space-forming member  34 B around the B discharge opening  23   b  by welding. 
     The B porous body  25   b  is joined to the B lid  24   b  by brazing or the like. As shown in  FIG. 8 , the B porous body  25   h  is formed in a rectangular parallelepiped shape. The B lid  24   b  is joined to one surface  27   a  of a pair of surfaces  27   a  and  27   b  of the B porous body  25   b  having the rectangular parallelepiped shape by brazing or the like. A shape and a size of the one surface  27   a  correspond to a shape and a size of a surface of the B lid  24   b  to which the B porous body  25   b  is joined. The other surface  27   b  of the pair of surfaces  27   a  and  27   b  of the B porous body  25   b  comes in contact with the cylinder-opposing plate  33   c  of the third B space-forming member  33 B or is adjacent to the cylinder-opposing plate  33   c . Of another pair of surfaces  27   c  and  27   d  of the B porous body  25   b  having the rectangular parallelepiped shape, the one surface  27   c  comes in contact with the upstream side plate  34   a  of the fourth B space-forming member  34 B or is adjacent to the upstream side plate  34   a . In addition, of the other pair of surfaces  27   c  and  27   d , the other surface  27   d  comes in contact with the downstream side plate  34   b  of the fourth B space-forming member  34 B or is adjacent to the downstream side plate  34   b.    
     Next, an operation and an action of the gas turbine of the embodiment will be described. 
     The compressor  1  suctions and compresses external air. The air compressed by the compressor  1  is guided to the fuel supply device  15  of the combustor  10 . Fuel from a fuel supply source is supplied into the fuel supply device  15 . The fuel from the fuel supply device  15  is sprayed into the combustion liner  12  together with the compressed air and combusted in the combustion liner  12 . A combustion gas generated by combustion and having a high temperature and a high pressure is guided into the gas flow path of the turbine  5  from the combustion liner  12  to rotate the turbine rotor  6 . 
     When the fuel is combusted in the combustion liner  12 , combustion oscillations may be generated by the combustion. In particular, when the fuel is lean-combusted in order to decrease NOx contained in the exhaust gas from the gas turbine, the combustion becomes unstable, and the combustion oscillations can easily occur. 
     In the embodiment, oscillations of the air generated by combustion of the fuel in the combustion liner  12 , such as combustion oscillation, i.e., sound, is suppressed by the sound attenuator  20  installed at the outer peripheral side of the combustion liner  12 . At least a portion of the space-forming member  21  of the sound attenuator  20  constitutes a Helmholtz resonance box, and at least a portion of the space S formed by the space-forming member  21  forms a resonance space. Accordingly, in the combustor  10  of the embodiment, as described above, the sound generated in the combustion liner  12  can be suppressed. Moreover, in the embodiment, since the porous body  25  is disposed in the space S formed by the space-forming member  21 , in a process in which the sound generated in the combustion liner  12  passes through the porous body  25  in the space S, oscillation energy thereof is absorbed, i.e., the sound is reduced. 
     Next, a method of repairing the combustor  10  will be described with reference to a flowchart shown in  FIG. 9 . 
     The gas turbine includes a member exposed to the high temperature combustion gas, a rotating member, and so on. For this reason, the gas turbine is periodically inspected. In the inspection process, when a member that is damaged or deteriorated is found, the member is exchanged or repaired. Since the combustor  10  of the gas turbine includes a member exposed to the high temperature combustion gas, the combustor  10  is repaired according to necessity. 
     Since the thermal barrier coating applied on the inner peripheral side of the combustion liner  12  is exposed to the high temperature combustion gas, the thermal barrier coating deteriorates or is damaged. For this reason, in repair of the combustor  10  according to the embodiment, after the thermal barrier coating that has deteriorated or been damaged is delaminated, the thermal barrier coating is applied to the inner peripheral side of the combustion liner  12  again (S 3 : cylinder repair step). 
     In the embodiment, after the combustion liner  12  is removed from the fuel supply device  15  before the cylinder repair step S 3 , the discharge opening  23  is formed at a portion in contact with the outside in the space-forming member  21  installed at the outer peripheral side of the combustion liner  12  (S 1 : opening step). In the opening step S 1 , as shown in  FIG. 10 , a welded portion  29  that joins the main body  22  and the lid  24  of the space-forming member  21  is removed by a grinder or the like, and the main body  22  and the lid  24  are separated from each other. As a result, the discharge opening  23  formed in the main body  22  is opened. In the process of separating the lid  24  from the main body  22 , the porous body  25  joined to the lid  24  is extracted to the outside from inside the space-forming member  21  via the discharge opening  23  (S 2 : porous body extraction step). Specifically, as shown in  FIG. 6 , as the A lid  24   a  that closes the A discharge opening  23   a  formed in the upstream side plate  33   a  of the third A space-forming member  33 A is moved upstream in the axial direction Da, the A porous body  25   a  joined to the A lid  24   a  is extracted to the outside from the third A space S 3   a  via the A discharge opening  23   a . In addition, as shown in  FIG. 8 , as the B lid  24   b  that closes the B discharge opening  23   b  formed in the cylinder-opposing plate  34   c  of the fourth B space-forming member  34 B is moved to the outside in the radial direction Dr, the B porous body  25   b  joined to the B lid  24   b  is extracted to the outside from the fourth B space S 4   b  via the B discharge opening  23   b.    
     Next, the above-mentioned cylinder repair step S 3  is performed. In the cylinder repair step S 3 , first, blast treatment is performed on the inner peripheral surface of the combustion liner  12  to which the thermal barrier coating is applied. In the blast treatment, ceramic or metal particles such as alumina particles collide with the inner peripheral surface of the combustion liner  12  and delaminate the thermal barrier coating. Next, as the metal powder or the ceramic powder having high thermal resistance is sprayed on the inner peripheral surface of the combustion liner  12  from which the thermal barrier coating is removed, the thermal barrier coating is formed on the inner peripheral surface again. 
     In the process of delaminating the thermal barrier coating, particles of a metal, ceramic, or the like, that form the thermal barrier coating, and particles of blasting metal or the like enter the space S formed by the space-forming member  21  via the large number of through-holes  14  of the combustion liner  12 . In addition, even in the process of applying the thermal barrier coating, particles of the metal, ceramic, or the like, that form the thermal barrier coating enter the space S formed in the space-forming member  21  via the large number of through-holes  14  of the combustion liner  12 . Further, even in an operation of the combustor  10 , various kinds of foreign substances enter the space S formed in the space-forming member  21  via the large number of through-holes  14  of the combustion liner  12 . 
     Next, the various kinds of foreign substances that have entered the space S are removed from the space S formed in the space-forming member  21  (S 4 : foreign substance removal step). In the foreign substance removal step S 4 , as shown in  FIG. 11 , various kinds of foreign substances  53  in the space S are discharged to the outside from the discharge opening  23  formed in the space-forming member  21  of the sound attenuator  20  by integrally shaking the combustion liner  12  and the sound attenuator  20  installed at the combustion liner  12  or by blowing off with air. 
     Next, the porous body  25  to which the lid  24  is joined is inserted into the space S from the discharge opening  23  formed in the space-forming member  21  (S 5 : porous body disposition step), simultaneously, the discharge opening  23  is closed by the lid  24 , and the lid  24  is joined to the main body  22  of the space-forming member  21  by welding or the like (S 6 : closing step). Further, the porous body  25  to which the lid  24  is joined may be that obtained in the above-described porous body extraction step S 2  or may be a new one. 
     Next, the combustor  10  is completed by assembling parts that constitute the combustor  10 , for example, attaching the combustion liner  12  to the fuel supply device  15 , or the like. Thus ends repair of the combustor  10 . 
     As described above, in the embodiment, the foreign substances can be easily removed from the inside of the space-forming member  21  of the sound attenuator  20 , and a time consumed for repairing the combustor  10  can be reduced. 
     In addition, in the embodiment, before the cylinder repair step S 3 , since the porous body  25  in the space S is extracted from the discharge opening  23  to the outside, the foreign substances such as a metal powder generated due to execution of the cylinder repair step S 3  can be prevented from being attached to the porous body  25 . In addition, as the porous body  25  is extracted from the space S, movement of the foreign substances in the space S becomes easy, and the foreign substances in the space S can be more easily removed to the outside. Moreover, in the embodiment, since the porous body  25  is joined to the lid  24 , in the opening step S 1 , when the main body  22  and the lid  24  are separated, the porous body  25  in the space S can be easily extracted from the discharge opening  23  to the outside. In addition, in the embodiment, since the porous body  25  joined to the lid  24  is disposed in the space S as the discharge opening  23  is closed by the lid  24 , the porous body  25  can be easily disposed in the space S. 
     Further, the space-forming member  21  of the above-described embodiment has the plurality of spaces formed at the outer peripheral side of the combustion liner  12  toward the outside in the radial direction Dr. However, the space-forming member  21  may form the plurality of spaces at the outer peripheral side of the combustor  10  in the axial direction Da, or the space-forming member  21  may form the plurality of spaces at the outer peripheral side of the combustion liner  12  toward the outside in the radial direction Dr, and further divide some or each of the plurality of spaces in the axial direction Da. 
     In addition, while the sound attenuator  20  of the above-described embodiment has the space-forming member  21  and the porous body  25 , the porous body  25  may be omitted. 
     INDUSTRIAL APPLICABILITY 
     According to an aspect of the present invention, the foreign substances can be easily removed from the inside of the sound attenuator of the combustor. 
     REFERENCE SIGNS LIST 
     
         
           1  compressor 
           5  turbine 
           10  combustor 
           12  combustion liner 
           14  through-hole 
           20  sound attenuator 
           21  space-forming member 
           22  main body 
           23  discharge opening 
           23   a  A discharge opening 
           23   b  B discharge opening 
           24  lid 
           24   a  A lid 
           24   b  B lid 
           25  porous body 
           25   a  A porous body 
           25   b  B porous body 
           31  first space-forming member 
           32  second space-forming member 
           32 A second A space-forming member 
           32 B second B space-forming member 
           33  third space-forming member 
           33 A third A space-forming member 
           33 B third B space-forming member 
           34  fourth space-forming member 
           34 A fourth A space-forming member 
           34 B fourth B space-forming member 
           53  foreign substance