JP2006029675A - Gas turbine combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine combustor capable of suppressing generation of slip stream related to the existence of swirler ring. <P>SOLUTION: This combustor 3 is provided with a main fuel nozzle 10, a main nozzle 21 storing a tip part 10a of the fuel nozzle 10 along a central axis from opening of a rear end and releasing compressed air taken in through the opening of the rear end from opening of a front end, the swirler ring 25 provided annularly by letting the main fuel nozzle 10 pass through coaxially, and a swirler 26 provided in a section from an outer peripheral face 25a of the swirler ring 25 to an inner peripheral face of the main nozzle 21 while supporting the swirler ring 25 to swivel compressed air around a central axis of the main nozzle 21. The swirler ring 25 satisfies the expression of 0.007≤t1/D<0.02 in a vertical cross sectional shape along a central axis of the main nozzle 21 (wherein, t1:wall thickness of a rear end 25c of the swirler ring 25 and D:inside diameter of the main nozzle 21). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas turbine combustor on which a gas turbine is mounted.

  In general, a gas turbine includes an air compressor (hereinafter simply referred to as “compressor”), a gas turbine combustor (hereinafter also simply referred to as “combustor”), and a turbine as a main component. A combustor is disposed between a compressor and a turbine directly connected to each other by a main shaft, and air serving as a working fluid is sucked into the compressor by the rotation of the main shaft and compressed, and the compressed air is transferred to the combustor. It is introduced and combusted with the fuel, and the high-temperature and high-pressure combustion gas is discharged to the turbine to rotate the main shaft together with the turbine. Such a gas turbine is used as a drive source for power generation equipment by connecting a generator or the like to the front end of the main shaft, and as a jet engine by disposing an exhaust port for combustion gas injection in front of the turbine. Be utilized.

  Here, a gas turbine that is more general than the conventional one using a premixed combustion type combustor, which has become the mainstream in recent years, will be described (for example, see Patent Document 1). As shown in FIG. 8, the gas turbine 1 mainly includes a compressor 2, a gas turbine combustor 3, and a turbine 4. The combustor 3 is attached to a casing 5 having a cavity formed between the compressor 2 and the turbine 4, and an inner cylinder 6 having a combustion region, and a tail cylinder 7 connected to the front end of the inner cylinder 6. The outer cylinder 8 concentrically with the inner cylinder 6, the pilot fuel nozzle 9 disposed from the rear end on the central axis of the inner cylinder 6, and circumferentially spaced around the pilot fuel nozzle 9 A plurality of main fuel nozzles 10, a bypass duct 11 connected to the side wall of the transition piece 7 and opening to the passenger compartment 5, a bypass valve 12 provided in the bypass duct 11, and the degree of opening and closing of the bypass valve 12 A variable bypass valve mechanism 13 is provided.

  However, as shown in FIG. 9, a cylindrical pilot nozzle 20 that accommodates the tip portion of the pilot fuel nozzle 9 along the central axis is disposed inside the inner cylinder 6. In addition, a cylindrical main nozzle 21 that houses the tip portion 10a of each main fuel nozzle 10 along the central axis is disposed. Here, the tip of the tip portion 10a of each main fuel nozzle 10 is tapered. Each main nozzle 21 is fixed to the inner cylinder 6 by a holder 22 and a holder 23 attached to the front ends thereof, and the pilot nozzle 20 is fixed to the inner cylinder 6 by the holder 22 and the holder 24.

  Further, a swirler ring 25 is provided in the main nozzle 21 so as to pass through the tip portion 10a of the main fuel nozzle 10 coaxially and be mounted around the parallel portion, and the main nozzle 21 extends from the outer peripheral surface 25a of the swirler ring 25. A swirler-like swirler 26 is disposed between the inner peripheral surface 21 and the inner peripheral surface 21. The swirler 26 has an outer peripheral end fixed to the inner peripheral surface of the main nozzle 21, and an inner peripheral end fixed to the outer peripheral surface 25 a of the swirler ring 25. As a result, the swirler ring 25 is swirled with respect to the main nozzle 21. It becomes the appearance supported through. Incidentally, similar swirler rings and swirlers are also provided for the pilot fuel nozzle 9 and the pilot nozzle 20.

  Further, a plurality of first fuel injection holes 27 are formed in the tip portion 10 a of the main fuel nozzle 10 at a position slightly ahead of the swirler ring 25 in a circumferential direction. Further, a plurality of hollow pillars 28 project radially and integrally at a position behind the swirler ring 25, and a plurality of second fuel ejection holes 29 are directed toward the swirler 26 in each of the hollow pillars 28. A plurality are formed. Incidentally, a fuel injection hole is formed at the tip of the pilot fuel nozzle 9.

  Under such a configuration, the compressed air compressed by the compressor 2 flows into the passenger compartment 5 (see the white arrow in FIG. 8), and the outer peripheral surface of the inner cylinder 6 and the inner periphery of the outer cylinder 8. After passing through the tubular space formed by the surface, it is reversed by approximately 180 degrees (see the solid arrow in FIG. 8) and introduced into the inner cylinder 6 from the rear end side. The compressed air is taken into the pilot nozzle 20 and the main nozzle 21 through the openings at the rear ends thereof. The compressed air taken into the main nozzle 21 becomes a spiral swirl around the central axis through the swirler 26 and is discharged from the opening at the front end. At that time, fuel is supplied from the first fuel injection hole 27 and the second fuel injection hole 29 in the main fuel nozzle 10, and the fuel is mixed with the compressed air flowing in the main nozzle 21. Similarly, the compressed air taken into the pilot nozzle 20 and swirled by the swirler is supplied with fuel from the fuel injection hole of the pilot fuel nozzle 9 and discharged from the opening at the front end.

  Next, the fuel mixture released from the pilot nozzle 20 burns to become a diffusion flame, and the fuel mixture from the main nozzle 21 is released into the diffusion flame to burn as a main flame, which is a high-temperature and high-pressure combustion. Gas is generated. Such a method of burning compressed air mixed with fuel in advance is called a premixed combustion method. The combustion gas is discharged from its front end via the tail cylinder 7 and drives the turbine 4. A part of the compressed air in the passenger compartment 5 is supplied from the bypass duct 11 into the tail cylinder 7, and thereby the combustion gas concentration in the inner cylinder 6 is adjusted.

  In such a premixed combustion type combustor 3, since fuel is uniformly dispersed in compressed air during combustion, a local increase in the temperature of the combustion flame can be suppressed. It is possible to reduce the amount of NOx generated that increases as the temperature rises. Therefore, the premixed combustion type combustor 3 is extremely useful for reducing NOx, which is a requirement for environmental conservation in recent years.

The first fuel injection hole 27 and the second fuel injection hole 29 in the main fuel nozzle 10 may be either one as long as the fuel can be uniformly supplied to the compressed air flowing in the main nozzle 21. The installation location is appropriately set according to the specifications of the combustor 3.
JP-A-9-119639

  By the way, the conventional swirler ring 25 in the main nozzle 21 is made of metal produced by precision casting or machining, and the inner and outer diameters thereof are from the front end mainly considering the ease of manufacture and ensuring the strength. Both were constant over the rear end and had a very simple shape with a certain thickness. That is, in the longitudinal section along the central axis of the main nozzle 21, the swirler ring 25 has a rectangular section. Therefore, the problem shown below has arisen.

  As shown in FIG. 10, most of the compressed air that circulates in the main nozzle 21 circulates through the swirler 26. At this time, the rear end 25c of the swirler ring 25 becomes a barrier, that is, a resistance. In the vicinity, stagnation occurs in the streamline of compressed air, and the streamline is bent sharply and then along the outer peripheral surface 25a of the swirler ring 25. That is, if it sees as the whole compressed air which distribute | circulates the swirler 26, local pressure loss will arise in the compressed air which distribute | circulates the swirler ring 25 vicinity.

  Therefore, the compressed air discharged from the main nozzle 21 does not have a uniform flow rate as a whole as shown by the dotted arrows in FIG. A region where the flow velocity is reduced in this phenomenon is generally called a wake. When the wake is excessively generated, that is, when the flow rate of the compressed air is greatly reduced, a so-called flashback in which the main flame flows backward is induced. The flashback burns the main nozzle 21 and thus the main fuel nozzle 10 and causes damage to them.

  Further, as shown in FIG. 11, when the swirler ring 25 is mounted around the tapered portion at the tip of the tip portion 10 a of the main fuel nozzle 10, the inner periphery of the swirler ring 25 at the rear end 25 c and the main fuel nozzle 10. The donut-shaped cross-sectional area formed by the gap with the outer periphery of the tip portion 10a is the donut-shaped cross-sectional area formed by the gap between the inner periphery at the front end 25d of the swirler ring 25 and the outer periphery of the tip portion 10a of the main fuel nozzle 10. A kind of diffuser is formed here. If it does so, about the compressed air which distribute | circulates there, the flow velocity of the front end side used as an exit will fall with respect to the flow velocity of the rear end side used as the inlet_port | entrance. For this reason, in addition to the wake according to the shape of the swirler ring 25 itself shown in FIG.

  Note that the same wake problem may occur for the compressed air flowing through the pilot nozzle 20.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a gas turbine combustor that can suppress the generation of a wake related to the presence of swirling.

  In order to achieve the above object, a gas turbine combustor according to the present invention accommodates a fuel nozzle for ejecting fuel and at least a front end portion of the fuel nozzle along a central axis from an opening at the rear end. A cylinder that discharges the compressed air that has been taken in from the opening at the front end, a swirler ring that is mounted by coaxially passing through the fuel nozzle, and an inner circumference of the cylinder from the outer circumferential surface of the swirler ring while supporting the swirler ring A gas turbine combustor provided with a swirler that swirls the compressed air that circulates around a central axis of the cylindrical body, the vertical section along the central axis of the cylindrical body of the swirler ring In the surface shape, the relational expression of 0.007 ≦ t1 / D <0.02 is satisfied. Where t1 is the thickness of the rear end of the swirler ring, and D is the inner diameter of the cylinder. In addition, a main nozzle and a pilot nozzle correspond as a cylinder here, and a main fuel nozzle and a pilot fuel nozzle correspond as a fuel nozzle.

  Thus, the compressed air flowing in the vicinity of the swirler ring receives almost no resistance at the rear end of the swirler ring, and its streamline smoothly follows the outer peripheral surface of the swirler ring. Therefore, among the compressed air released from the cylinder, the flow velocity of the compressed air near the center in the radial direction originating from the compressed air that has circulated in the vicinity of the swirler ring is maintained with almost no decrease.

  Here, from the viewpoint of maintaining the flow velocity of the compressed air in the vicinity of the radial center discharged from the cylinder without further lowering, the streamline of the compressed air along the outer peripheral surface of the swirler ring is finally on the radial center side. It is preferable that the vertical cross-sectional shape of the swirler ring is a streamline shape so as to be inclined. Alternatively, in the vertical cross-sectional shape of the swirler ring, the outer peripheral side of the front end may be chamfered.

  Similarly, from the viewpoint of maintaining the flow velocity of the compressed air near the radial center discharged from the cylindrical body without lowering the compressed air, the compressed air is also introduced into the gap between the inner peripheral surface of the swirler and the outer peripheral surface of the fuel nozzle. The cross-sectional area formed by the gap between the inner circumference at the rear end of the swirler ring and the outer circumference of the fuel nozzle is such that the gap between the inner circumference at the front end of the swirler ring and the outer circumference of the fuel nozzle is It is preferable that the cross-sectional area formed by

  Here, for example, the swirler ring is mounted at the tapered tip of the fuel nozzle, and the inner peripheral surface of the swirler ring and the outer peripheral surface of the fuel nozzle that face each other in a longitudinal section along the central axis of the cylindrical body Are preferably parallel to each other.

  Practically, the gap between the inner peripheral surface of the swirler ring and the outer peripheral surface of the fuel nozzle is preferably at least twice the thickness of the rear end of the swirler ring.

  According to the gas turbine combustor of the present invention, among the compressed air discharged from the cylinder, the flow velocity of the compressed air near the center in the radial direction originating from the compressed air that has circulated in the vicinity of the swirler ring is hardly reduced. Therefore, the occurrence of wake is suppressed. As a result, the occurrence of flashback can be remarkably prevented.

  Hereinafter, an embodiment of a combustor of the present invention will be described in detail with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 is an enlarged longitudinal sectional view showing a main part of the combustor according to the first embodiment. In addition, in the figure, the same code | symbol is attached | subjected to the part which performs the same function by the same name as FIGS. The same applies to the second to sixth embodiments described later.

In the first embodiment, as shown in FIG. 1, the swirler ring 25 in the main nozzle 21 is mounted around the parallel portion of the tip portion 10a of the main fuel nozzle 10, and the outer peripheral surface 25a in the portion of the rear end 25c. The diameter is gradually reduced toward the rear. And in the longitudinal cross-sectional shape along the central axis of the main nozzle 21, the thickness of the rear end 25c of the swirler ring 25 is t1, and the inner diameter of the main nozzle 21 is D, so that the following relational expression (1) is satisfied. .
0.007 ≦ t1 / D <0.02 (1)

  Specifically, for the combustor 3 applied to a large gas turbine (the inner diameter D ≧ 50 mm of the main nozzle 21), for example, when D = 75 mm, 0.5 mm based on the relational expression (1) above. ≦ t1 <1.5 mm is derived. If the wall thickness t1 of the rear end 25c of the swirler ring 25 is within this range, the swirler ring 25 can be secured with sufficient dimensional accuracy especially when easily manufactured using precision casting, and there is no problem in strength. Incidentally, in this case, the maximum thickness tmax of the swirler ring 25 is about 1.5 mm in consideration of securing the yield.

  When such a swirler ring 25 is applied, the compressed air flowing in the vicinity of the swirler ring 25 receives almost no resistance of the rear end 25c of the swirler ring 25, and its streamline smoothly follows the outer peripheral surface 25a of the swirler ring 25. Become. Therefore, among the compressed air discharged from the main nozzle 21, the flow velocity of the compressed air near the center in the radial direction originating from the compressed air that has circulated in the vicinity of the swirler ring 25 is maintained with almost no decrease. That is, the occurrence of the wake is suppressed, and as a result, the occurrence of backfire can be remarkably prevented.

  Next, a second embodiment of the present invention will be described with reference to FIG. The feature of the second embodiment is that the first embodiment is modified to reduce the wake. In addition, the description which overlaps with 1st Embodiment is abbreviate | omitted suitably. The same applies to third to sixth embodiments to be described later.

  In the second embodiment, as shown in FIG. 2, the swirler ring 25 has a streamline shape in the longitudinal sectional shape along the central axis of the main nozzle 21. Of course, the wall thickness t1 of the rear end 25c of the swirler ring 25 satisfies the relational expression (1).

  If it does in this way, the streamline of the compressed air along the outer peripheral surface 25a of the swirler ring 25 will finally incline to the radial direction center side. Therefore, it becomes possible to maintain the flow velocity of the compressed air near the radial center discharged from the main nozzle 21 without further decreasing, and as a result, the wake is reduced.

  Next, a third embodiment of the present invention will be described with reference to FIGS. The feature of the third embodiment is that, from the same viewpoint as the second embodiment described above, the first embodiment is modified to reduce the wake.

  In the third embodiment, as shown in FIGS. 3 and 4, the swirler ring 25 is chamfered on the outer peripheral surface 25 a side of the front end 25 d in the longitudinal sectional shape along the central axis of the main nozzle 21. FIG. 3 shows an R-chamfered mode, and FIG. 4 shows a C-chamfered mode. Of course, the thickness t1 of the rear end 25c of the swirler ring 25 also satisfies the relational expression (1).

  Even in this case, as in the second embodiment, the streamline of the compressed air along the outer peripheral surface 25a of the swirler ring 25 finally tilts toward the center in the radial direction. It becomes possible to maintain the flow velocity of the compressed air near the center of the direction without further lowering, and as a result, the wake is reduced. The swirler ring 25 in the present embodiment is advantageous in terms of ease of manufacture because of its simple shape as compared with the second embodiment.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. The feature of the fourth embodiment is that the downstream flow is further reduced while utilizing the feature points of the first embodiment.

  In the fourth embodiment, as shown in FIG. 5, the swirler ring 25 is gradually enlarged in diameter as the inner peripheral surface 25 b goes rearward. Of course, the wall thickness t1 of the rear end 25c of the swirler ring 25 satisfies the relational expression (1).

  In this way, the donut-shaped cross-sectional area formed by the gap between the inner periphery at the rear end 25c of the swirler ring 25 and the outer periphery of the tip portion 10a of the main fuel nozzle 10 is the same as the inner periphery and the main at the front end 25d of the swirler ring 25. It becomes larger than the cross-sectional area of the donut shape formed by the gap with the outer periphery of the tip portion 10a of the fuel nozzle 10. Then, with respect to the compressed air flowing in the gap between the inner peripheral surface 25b of the swirler ring 25 and the outer peripheral surface of the front end portion 10a of the main fuel nozzle 10, the front end side serving as the outlet with respect to the flow velocity on the rear end side serving as the inlet. Increases the flow rate. Therefore, it becomes possible to maintain the flow velocity of the compressed air near the radial center discharged from the main nozzle 21 without further decreasing, and as a result, the wake is reduced.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. A feature of the fifth embodiment is that the fourth embodiment is modified.

  In the fifth embodiment, as shown in FIG. 6, the swirler ring 25 is attached to the tapered portion at the tip of the tip portion 10 a of the main fuel nozzle 10, and gradually increases as the inner peripheral surface 25 b goes rearward. The diameter has been expanded. That is, in the longitudinal section along the central axis of the main nozzle 21, the inner peripheral surface 25b of the swirler ring 25 and the outer peripheral surface of the tip portion 10a of the main fuel nozzle 10 are opposed to each other and are parallel to each other. Of course, the wall thickness t1 of the rear end 25c of the swirler ring 25 satisfies the relational expression (1).

  In this way, inevitably, the donut-shaped cross-sectional area formed by the gap between the inner periphery at the rear end 25c of the swirler ring 25 and the outer periphery of the front end portion 10a of the main fuel nozzle 10 is the inner portion at the front end 25d of the swirler ring 25. Since it becomes larger than the donut-shaped cross-sectional area formed by the gap between the circumference and the outer circumference of the tip portion 10a of the main fuel nozzle 10, the same effect as in the fourth embodiment described above can be obtained.

  Next, a sixth embodiment of the present invention will be described with reference to FIG. The feature of the sixth embodiment is that the downstream flow is further reduced from the same viewpoint as that of the above-described fourth embodiment while utilizing the feature points of the first embodiment.

  In the sixth embodiment, as shown in FIG. 7, the gap C between the inner peripheral surface 25b of the swirler ring 25 and the outer peripheral surface of the tip portion 10a of the main fuel nozzle 10 is the thickness t1 of the rear end 25c of the swirler ring 25. It has become more than twice. That is, the relationship of C / t1 ≧ 2 is satisfied. Of course, the wall thickness t1 of the rear end 25c of the swirler ring 25 satisfies the relational expression (1).

  If it does in this way, compressed air will be able to distribute | circulate also in the clearance gap between the inner peripheral surface 25b of the swirler ring 25, and the outer peripheral surface of the front-end | tip part 10a of the main fuel nozzle 10 without the flow velocity fall. Therefore, as in the fourth embodiment, the flow rate of the compressed air discharged from the main nozzle 21 in the vicinity of the center in the radial direction can be maintained without lowering, and as a result, the downstream flow is reduced. However, if C / t1 is set too large, the function of the swirler 26 (applying a swirling flow to the compressed air) is lowered, so care must be taken.

  In the present embodiment, “2” is adopted as the lower limit value of C / t1, but this is based on the results of experiments and analyses. This is because, while the flow velocity is almost constant, the flow velocity rapidly decreases as “2” becomes a boundary.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the swirler ring 25 having a shape that satisfies the above-described relational expression (1) can be applied to a small and medium-sized gas turbine (the inner diameter D <50 mm of the main nozzle 21). However, in this case, the wall thickness t1 of the rear end 25c of the swirler ring 25 is reduced, but its manufacture can be realized by using machining such as electric discharge machining. In each of the above embodiments, the swirler ring 25 in the main nozzle 21 has been described. However, the present invention can be similarly applied to the swirler ring in the pilot nozzle 20.

  The present invention is useful for gas turbine combustors.

It is a longitudinal cross-sectional view which expands and shows the principal part of the combustor of 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the combustor of 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the combustor of 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the other combustor of 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the combustor of 4th Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the combustor of 5th Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the combustor of 6th Embodiment of this invention. It is a longitudinal cross-sectional view near the combustor of a general gas turbine. It is a longitudinal cross-sectional view which shows the principal part of the conventional combustor. It is a longitudinal cross-sectional view which expands and shows the principal part of the conventional combustor. It is a longitudinal cross-sectional view which expands and shows the principal part of the other conventional combustor.

Explanation of symbols

3 Gas Turbine Combustor 6 Inner Tube 9 Pilot Fuel Nozzle 10 Main Fuel Nozzle 10a Main Fuel Nozzle Tip 20 Pilot Nozzle 21 Main Nozzle 25 Swirler Ring 25a Swirler Ring Outer Face 25b Swirler Ring Inner Face 25d Swirler Front End 25c After Swirling End 26 Swirler t1 Thickness of rear end of swirler ring D Inner diameter of main nozzle

Claims (6)

A fuel nozzle that ejects fuel, a cylindrical body that accommodates at least the front end portion of the fuel nozzle along the central axis from the opening at the rear end, and discharges compressed air taken from the opening at the rear end from the opening at the front end; A swirler ring that is installed by coaxially penetrating a fuel nozzle, and the compressed air that is circulated from the outer peripheral surface of the swirler ring to the inner peripheral surface of the cylindrical body while supporting the swirler ring. A gas turbine combustor comprising a swirler that swirls about a central axis of the body,
A gas turbine combustor that satisfies the following relational expression in a vertical cross-sectional shape along a central axis of the cylindrical body of the swirler ring.
0.007 ≦ t1 / D <0.02
Where t1 is the thickness of the rear end of the swirler ring, and D is the inner diameter of the cylinder.   The gas turbine combustor according to claim 1, wherein the vertical cross-sectional shape of the swirler ring is a streamline shape.   2. The gas turbine combustor according to claim 1, wherein an outer peripheral side of a front end is chamfered in the vertical cross-sectional shape of the swirler ring.   The cross-sectional area formed by the gap between the inner periphery at the rear end of the swirler ring and the outer periphery of the fuel nozzle is larger than the cross-sectional area formed by the gap between the inner periphery at the front end of the swirler ring and the outer periphery of the fuel nozzle. The gas turbine combustor according to any one of claims 1 to 3, wherein the gas turbine combustor is configured.   The swirler ring is attached to the tapered tip of the fuel nozzle, and the inner peripheral surface of the swirler ring and the outer peripheral surface of the fuel nozzle facing each other are parallel to each other in a longitudinal section along the central axis of the cylindrical body. The gas turbine combustor according to claim 4, wherein the gas turbine combustor is provided.   The clearance gap between the inner peripheral surface of the said swirler ring and the outer peripheral surface of the said fuel nozzle is 2 times or more of the thickness of the rear end of the said swirler ring, The Claim 1 characterized by the above-mentioned. Gas turbine combustor.

Images