Fuel jetting nozzle assembly for use in gas turbine combustor

Abstract: A fuel jetting nozzle assembly for use in a gas turbine combustor comprises a nozzle head secured to a head plate, a fuel jetting nozzle (10) secured to the nozzle head and having fuel jetting holes (17) opened to an inside of a combustion chamber, swirling vanes (16) disposed on an outer peripheral portion of the fuel jetting nozzle for supplying air (27) as an annular swirling flow in the combustion chamber of the combustor liner, the fuel jetting holes being formed at base portions of the swirling vanes, and a cooling member composed of a plurality of cooling holes (30) formed to a front end portion of the fuel jetting nozzle so as to introducing a portion of the air (31) into a forward portion of a central portion (18) of the front end portion of the nozzle jetting from an upstream side of the swirling vanes. The cooling member further comprises an air introducing pipe (32) disposed to the front end portion of the fuel jetting nozzle means and an air header (33) attached to an inner surface of the front end portion of the fuel jetting nozzle. The cooling member is substituted by a pipe member formed to the nozzle head for jetting a fuel (20) inside the fuel jetting nozzle and colliding the jetted fuel against an inner surface of the central portion of the front end portion of the fuel jetting nozzle so as to cool the central portion thereof.

Description: BACKGROUND OF THE INVENTION The present invention relates to a fuel jetting nozzle assembly for use in a gas turbine combustor, particularly, in which a burn damage to the central portion of the extreme end portion of the fuel jetting nozzle is prevented as much as possible. Figs. 6 to 8 explained hereinafter, represents an example of a typical well-known gas turbine combustor of a conventional structure. Referring to Figs. 6 to 8, a plurality of gas turbine combustors are arranged on the outer peripheral portion of a discharge casing 2 of an air conditioner 1. A combustor liner 5 by which an internal combustion chamber 4 is enclosed is housed within the combustor casing 3, and a nozzle head 6, an igniter 7 and a flame detector, not shown, are provided in the internal combustion chamber 4. The nozzle head 6 is mounted on a head plate 8, and this head plate 8 and a flow sleeve 9 are mounted on the combustor casing 3. The head plate 8 is disposed so as to close one end of the casing 3. A fuel jetting nozzle 10 is mounted on the nozzle head 6 and prevented from rotating by a locking plate 11. The combustor liner 5 is mounted on the extreme, i.e. front, end portion of the fuel jetting nozzle 10, and a liner supporter 12 provided on the flow sleeve 9 supports the combustor liner 5. A transition piece 13 is connected to the extreme end portion (the downstream area) of the combustor liner 5. The combustor liner 5 is connected to a first-stage turbine stationary blade 14a of a gas turbine 14 by way of the transition piece 13. An air intake passage 15 is formed in the outer peripheral portion of the fuel jetting nozzle 10. A swirl vane 16 is disposed between the air intake passage 15 and the internal combustion chamber 4. Fuel jetting holes 17, through which the inside of the fuel jetting nozzle 10 is communicated with the swirl vane 16, are provided on the peripheral wall portion of the fuel jetting nozzle 10. The front side of a central end portion 18 of the fuel jetting nozzle 10 faces the inside of the internal combustion chamber 4 and forms a portion thereof. A fuel intake 19 is formed in the nozzle head 6, from which a gaseous fuel 20 is introduced into the fuel jetting nozzle 10. An air flow around the gas turbine combustor will be explained hereunder. An air 21 discharged from the air conditioner 1 flows around the transition piece 13 and is guided in a direction opposite to the flow of combustion gas 22 between the combustor liner 5 and the flow sleeve 9. The discharged air 21 is introduced into the internal combustion chamber 4 through air passages which are broadly divided into three portions. That is, the discharged air 21 is divided into primary air 23 introduced from the swirl vane 16 around the fuel jetting nozzle 10, secondary air 25 introduced from an air guide 24 provided on the trunk portion of the combustor liner 5, and tertiary air 26 for dilution purposes introduced from the holes provided downstream of the air guide 24 used for the secondary air. A stable annular vortex area, i.e. flame area, of the primary air 23 and the gaseous fuel 20 is formed in the inside of the annular swirl flow caused by the primary air 23. The stable annular vortex area stabilizes and maintains the combustion flame, and the combustion gas 22 flows to the exit area of the combustor liner 5. The primary air 23 is mixed with the tertiary air 26, and cools the combustor liner 5 and decreases the gas temperature so that the liner exit temperature becomes a temperature required for the turbine. In this viewpoint, the primary air 23, the secondary air 25 and the tertiary air 26 are allocated in various ways so as to control combustion performance. In some instances, the secondary air 25 and tertiary air 26 may not be provided. Furthermore, the primary air 23 and the secondary air 25 may be mixed with the gaseous fuel 20 beforehand and introduced into the internal combustion chamber 4. The discharged air 21 passes through a slot, not shown, used to cool the combustor liner 5 and is supplied to the internal combustion chamber 4. The details of the fuel jetting nozzle 10 are shown in Fig. 7. Some of the primary air 23 of the discharged air 21 discharged from the air compressor 1 enters from the air intake passage 15 into the internal combustion chamber 4. At this time, the air is mixed with the gaseous fuel 20 jetted from the fuel jetting holes 17, passes the swirl vane 16 disposed around the fuel jetting nozzle 10, is jetted into the internal combustion chamber 4 while it is being swirled and is then ignited. Ignition is performed by the igniter 7 shown in Fig. 9. The combustion gas 22 passes the transition piece 13 and is introduced to the first-stage turbine stationary blade 14a of the gas turbine 14, causing a turbine rotor, not shown, to rotate by using the energy thereof. The flow of gas near the outlet of the fuel jetting nozzle 10 inside the internal combustion chamber 4 is shown in Fig. 8. The primary air 23 passes the swirl vanes 16 of the fuel jetting nozzle 10 and flows into the internal combustion chamber 4 while it is being swirled. The secondary air 25 which flows into the internal combustion chamber 4 through the air guide 24 provided in the trunk portion of the combustor liner 5 flows into a swirling flow 27 formed by air passing through the fuel jetting nozzle 10, forming a reverse flow, i.e. vortex flow, flame area 28 in the central portion and a reverse flow, i.e. vortex flow, flame area 29 in the outer periphery. The local temperature of the combustion gas inside the reverse flow flame area 28 in the central portion becomes a high temperature above approximately 2,000°C and a stable flame can thus be maintained. However, in the above-described conventional fuel jetting nozzle for use in a gas turbine combustor, problems arise. For example, the central end portion 18 of the fuel jetting nozzle 10 is burned by radiation and forced convection by high-temperature gas of the reverse flow flame area 28 in the central portion, and the service life of the fuel jetting nozzle 10 becomes short. GB-A 2 101 732 discloses a fuel jetting nozzle assembly with the fuel ducts, which leads into a cylindrical housing, which is closed to the combustion chamber and provided with the an end cap. The end of the fuel duct is formed with radial fuel outlets, which are coaxial with radial ducts formed in the housing and ending downstream of the swirl vanes circumferring said housing. The space between the end cap and the housing is supplied with air through axial ducts formed in said housing. The air flows out into combustion chamber through openings or holes, which are inclined. The mouth of the radial ducts into the combustion chamber being downstream of the swirl vanes means that the velocity of air flowing through swirl vanes is reduced at the mouth of the radial ducts, which means that the efficiency of the air stream to form fuel droplets or vaporize the fuel is reduced. Furthermore, the path of the fuel delivered from the fuel outlets leads through the interior of the housing, which is also open to air, to the radial ducts formed in the circumferring wall of the housing. This means that the fuel may not et all help to cool the end wall of the housing. From WO-A 82/02244 there is known an injector for combustible fuels, which includes a fuel pipe, which leads to the interior of a distribution chamber contained in a body, which is provided with radial ports. The fuel is expelled from the distribution chamber through the ports and drawn by pulverization air flowing through channels defined by the outer surface of the body, swirl vanes and an internal surface of a further body surrounding said body. The mouth of the ports into the channels is within the channels on their upstream side. The end wall of the body is cooled only by the fuel flowing through the distribution chamber. SUMMARY OF THE INVENTION It is an object of the present invention to substantially eliminate defect or drawbacks encountered int he prior art described above and to provide an efficient fuel jetting nozzle assembly for use in a gas turbine combustor and in which service life of the fuel jetting nozzle is lengthened by preventing a burn damage to the central end portion of the jetting nozzle by a location of a cooling means. A first solution of this object is achieved by a fuel jetting nozzle assembly according to appended claim 1. Appended subclaims 2 to 4 are directed towards advantageous embodiment of the fuel jetting nozzle assembly according to claim 1. A further solution on the object of the invention is achieved by a fuel jetting nozzle assembly according to appended claim 5. Subclaims 6 to 8 are directed towards advantageous embodiments of the fuel jetting nozzle assembly according to claim 5. According to the present invention the central end portion of the fuel jetting nozzle is cooled by the first convection of air with passes through cooling holes and the air is introduced to the front side thereof. The central end portion of the fuel jetting nozzle can be cooled by an air layer formed by that air in the central end portion of the fuel jetting nozzle. As a result, a burn damage to the fuel jetting nozzle can be prevented. Furthermore according to the present invention, the high-temperature portion of the central end portion of the fuel jetting nozzle can be cooled by the forced convection using colliding jets caused by a gaseous fuel which is introduced by the cooling means. As a result, the burn damage to the fuel jetting nozzle can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention and to show how the same is carried out, reference will be made, by way of preferred embodiments, to the accompanying drawings, in which: Fig. 1 is a sectional view illustrating a fuel jetting nozzle assembly for use in a gas turbine combustor similar to the inventive assembly in some details; Fig. 2 is a sectional view illustrating a first embodiment of the present invention; Fig. 3 is a sectional view illustrating a second embodiment of the present invention; Fig. 4 is a sectional view illustrating a modification of Fig. 3, Fig. 5 is a sectional view illustrating another modification of Fig. 3, Fig. 6 is a sectional view illustrating a conventional gas turbine combustor; Fig. 7 is an expanded view of the essential portion of the fuel jetting nozzle provided in the gas turbine combustor shown in Fig. 6 and Fig. 8 is a view illustrating the relationship between the swirl flow inside the combustion chamber of the conventional fuel jetting nozzle and the flow of the secondary air. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be explained hereunder with reference to Figs. 1 to 5. Figs. 1 illustrates an embodiment of a fuel jetting nozzle assembly for use in a gas turbine combustor, which assembly includes some parts which are very similar to or identical with the corresponding ones of the inventive assembly corresponding to Fig. 2 to 5. Components which are the same as those in a conventional fuel jetting nozzle assembly shown in Figs. 6 to 8 are given the same reference numerals, and thus an explanation thereof is omitted herein. A basic difference of the fuel jetting nozzle of the present invention from the conventional one is that a plurality of swirl vanes 16 by which fuel air is made to flow into the internal combustion chamber 4 are evenly arranged circumferentially on the outer peripheral portion of the fuel jetting nozzle 10, and that fuel jetting holes 17 are provided on the base portions of the swirl vanes 16. The fuel jetting nozzle 10 is fastened to the nozzle head 6 having the fuel intake 19. Each of cooling holes 30, formed at the base portions of the respective swirl vanes 16 and positioned between the adjacnet two fuel jetting holes 17, which reaches the front of the central portion 18 of the front end portion of the fuel jetting nozzle 10 from an area upstream of the swirl vanes 16, is provided on the peripheral wall of the fuel jetting nozzle 10. Each of the cooling holes 30 is provided with an inward angle γ with respect to the front side of the central end portion 18 of the fuel jetting nozzle 10. Furthermore, it has a swirl angle component in the same direction as that of the swirl angle of the swirl vanes 16. The operation of this embodiment will be explained hereunder Some of the air 21, discharged from the air compressor 1, passes the swirl vanes 16 as the primary air 23, becomes an annular swirl flow and flows into the internal combustion chamber 4. As a result, a reverse flow, i.e vortex flow, flame area is formed in the central portion. At the same time, some of the discharged air 21 flows into the cooling holes 30 as cooling air 31. This cooling air 31 flows out to the front side of the central flame area while it takes away heat by forced convection cooling, which heat flows in from the front side of the fuel jetting nozzle 10. The air flown out to the front side of the central flame area forms an air layer in front of the central end portion 18 of the fuel jetting nozzle 10. Thus, the front side is protected from fuel gas by film-cooling effect. Fig. 2 illustrates a first embodiment of a fuel jetting nozzle for use in a gas turbine combustor according to the present invention. A point of difference of this embodiment from the fuel jetting nozzle according to Fig. 1 is that a pipe 32 and an air header 33 are provided, and that when once some of the discharged air 21 is introduced by the pipe 32 as the cooling air 31 into the air header 33, the air is made to flow out from the inside of the header to the front side of the central end portion 18 of the fuel jetting nozzle 10 through a plurality of cooling holes 30. The air introducing pipe 32 is mounted to the front end portion of the fuel jetting nozzle and the air header 33 is attached to an inner surface of the front end portion of the fuel jetting nozzle, the air introducing pipe 32 having one end communicated with the air header 33 and another end opened to a discharge air side. According to this embodiment, since the cooling holes 30 can be compactly arranged as desired, a minimum amount of cooling air required can be allocated on the basis of the distribution of the amount of heat which enters from the gaseous fuel 20 into the fuel jetting nozzle 10. Thus, the front side of the central end portion 18 of the fuel jetting nozzle 10 can be cooled more uniformly. Fig. 3 illustrates a second embodiment of a fuel jetting nozzle for use in a gas turbine combustor according to the present invention. A plurality of swirl vanes 16 by which fuel air is made to flow in are evenly arranged circumferentially on the outer peripheral portion of the fuel jetting nozzle 10, and fuel jetting holes 17 are provided on the base portions of the swirl vanes 16. This is fastened to the nozzle head 6 having the fuel intake 19. A pipe 34, serving as cooling means, for introducing the gaseous fuel 20 to the inner side of the central end portion 18 of the fuel jetting nozzle 10 is disposed in the central portion. The pipe 34 has one end communicated with the nozzle head and another end opened in the fuel jetting nozzle 10. In this embodiment, some of the discharged air 21 discharged from the air compressor 1, as shown in Fig. 6, flows into the internal combustion chamber 4 from the air intake passage 15 as the primary air 23. The gaseous fuel 20 flows in from the fuel intake 19, passes through the pipe 34, flows out into the fuel jetting nozzle 10 in the form of jets, and collides with the inner side of the central end portion 18, thereby cooling this portion by the forced convection. Thereafter, the gaseous fuel 20 is jetted from the fuel jetting holes 17, mixed with the primary air 23, passes the swirl vanes 16 provided in the periphery of the fuel jetting nozzle 10, and flows out as an annular swirl flow into the internal combustion chamber 4, forming the central reverse flow flame area 28. As shown in Fig.4 when the forced convection cooling is performed by making the gaseous fuel 20 collide with the inner side of the central end portion 18 of the fuel jetting nozzle 10, the front side of the central end portion 18 of the fuel jetting nozzle 10 may be coated (thermal barrier coating) with a material 35, such as zirconium oxide, having thermal conductivity lower than that of component metals of the fuel jetting nozzle 10 in order to reduce thermal stress caused by a temperature difference with the inside of the combustion chamber 4. According to this embodiment, as described above, since the inner side of the central end portion 18 of the fuel jetting nozzle 10 can be cooled by the forced convection using the gaseous fuel 20, a burn damage to the fuel jetting nozzle 10 can be prevented. In addition, as shown in Fig. 5 a porous plate 36 may be provided in the extreme end portion of the pipe 34 serving as cooling means to make it possible to cool the inner side of the central end portion 18 of the fuel jetting nozzle 10 by a plurality of colliding jets.

Claims: A fuel jetting nozzle assembly for use in a gas turbine combustor comprising an outer casing, a combustor liner disposed inside the outer casing and having a combustion chamber, a head plate closing one end of the outer casing and a fuel jetting nozzle assembly, said fuel jetting nozzle assembly comprising: a nozzle head (6) securable to the head plate and having a fuel intake (19); a fuel jetting nozzle means (10) secured to the nozzle head (6) said fuel jetting nozzle means (10) and said nozzle head (6) defining a fuel chamber therebetween, said fuel intake (19) supplying fuel to said fuel chamber; a swirling means (16) disposed on an outer peripheral portion of the fuel jetting nozzle means (10) for supplying air as an annular swirling flow in the combustion chamber of the combustor liner, said fuel jetting nozzle means (10) comprising fuel jetting holes (20) formed at a base portion of the swirling means (16) for introducing fuel from the fuel chamber into the swirling air flow; a cooling means (32, 33, 30) formed at a front end portion of the fuel jetting nozzle means (10) so as to introduce a portion of the air into a forward portion of a central portion of the front end portion of the fuel jetting nozzle means (10) from an upstream side of the swirling means (16) so as to flow the air into the combustion chamber. A fuel jetting nozzle assembly according to claim 1, wherein said cooling means (32, 33, 30) is composed of a plurality of cooling holes (30). A fuel jetting nozzle assembly according to claim 2, wherein said swirling means comprises a plurality of swirling vanes (16) disposed on the outer peripheral portion of the fuel jetting nozzle means (10) and separated equally. A fuel jetting nozzle assembly according to claim 1 or 2, wherein said cooling means (32, 33, 30) comprises an air introducing pipe (32) disposed at the front end portion of the fuel jetting nozzle means (10) and an air header (33) attached to an inner surface of the front end portion of the fuel jetting nozzle means (10), said air introducing pipe having one end communicated with the air header and another end opened to an upstream side of the swirling means (16), said front end portion of the fuel jetting nozzle means (10) having a plurality of cooling holes from the air header (33) to the front side of the central end portion (18) of the fuel jetting nozzle means (10). A fuel jetting nozzle assembly for use in a gas turbine combustor comprising an outer casing, a combustor liner disposed inside the outer casing and having a combustion chamber, a head plate closing one end of the outer casing and a fuel jetting nozzle assembly, said fuel jetting nozzle assembly comprising: a nozzle head (6) securable to the head plate and having a fuel intake (19); a fuel jetting nozzle means (10) secured to the nozzle head (6) said fuel jetting nozzle means (10) and said nozzle head (6) defining a fuel chamber therebetween, said fuel intake (19) supplying fuel to said fuel chamber; a swirling means (16) disposed on an outer peripheral portion of the fuel jetting nozzle means (10) for supplying air as an annular swirling flow in the combustion chamber of the combustor liner, said fuel jetting nozzle means (10) comprising fuel jetting holes (20) formed at a base portion of the swirling means (16) for introducing fuel from the fuel chamber into the swirling air flow; a cooling means (34; 35) formed at the nozzle head (6) for jetting a fuel inside the fuel jetting nozzle means and colliding the jetted fuel against an inner surface of the central portion (18) of the front end portion of the fuel jetting nozzle means (10) so as to cool the central portion thereof, wherein said cooling means comprises a pipe (34) having one end communicated with the fuel intake (19) and another end opened in said fuel chamber, said another end of the pipe (34) having a plurality of fuel jetting holes. A fuel jetting nozzle assembly according to claim 5, wherein a coating (35) is applied to the front surface of the central portion (18) of the front end portion of the fuel jetting nozzle means (10) with a substance having a thermal conductivity lower than that of a substance constituting the fuel jetting nozzle means. A fuel jetting nozzle assembly according to claim 6, wherein said coating material is a zirconium oxide. A fuel jetting nozzle assembly according to claim 5, wherein said swirling means comprises a plurality of swirling vanes (16) disposed on the outer peripheral portion of the fuel jetting nozzle means (10) and separated equally.

Inventors: KOBAYASHI TAKAHIRO, OKAMOTO HIROAKI, KOBAYASHI, TAKAHIRO, OKAMOTO, HIROAKI
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1992
Main classification: F23D14
IPC codes: F23D14