JP2004197696A - Gas turbine equipped with whirling nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine with a rotor 41 having an elongated life by reducing the relative speed of cooling compressed air A and the rotor 41 without requiring a large-sized installation space to effectively lower the temperature of cooling compressed air to thereby improve the cooling efficiency of the rotor 41. <P>SOLUTION: The gas turbine is equipped with a compressor 2; a combustor 3, designed to burn compressed air A from the compressor 2; a turbine 4, designed to extract power out of combustion gas G from the combustor 3; an inner casing 20 covering the outer circumference of the rotor 41 to form an inner circumference wall for a channel 21 for the compressed air A at the downstream side of the compressor 2; and a whirling nozzle 5 for whirling the air A in the rotational direction of the rotor 41 to introduce it to the external circumference of the rotor 41 through the outer circumference of the rotor 41. The rotor 41 has a flow-out hole 55, which is designed to flow the compressed air A introduced to the outer circumference of the rotor 41, to the turbine rotor 41r, fitted with a turbine moving blade 44, via the hollow potion 60 of the rotor 41. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas turbine configured to perform efficient cooling of a rotor by swirling cooling air.
[0002]
[Prior art]
A turbine that extracts power from combustion gas in a gas turbine has a particularly high temperature, so cooling is an issue. Therefore, a part of the compressed air flowing from the compressor to the combustor is jetted radially inward toward the outer peripheral surface of the rotor for cooling, and then is taken into the rotor (hollow portion) to form a turbine at the rear. A cooling structure for introducing a turbine rotor having a moving blade is known. However, since the cooling structure ejects the compressed air in the radial direction, the relative speed between the ejected compressed air and the rotor increases, resulting in a large power loss. In addition, the increase in the power loss causes a rise in the temperature around the rotor and a rise in the temperature of the compressed air for cooling.
[0003]
[Problems to be solved by the invention]
On the other hand, there is an axial flow type pre-swirl nozzle that jets compressed air for cooling in an oblique axial direction toward a turbine rotor that forms a rear portion of the rotor, and cools the turbine rotor by air from the nozzle ( See, for example, Patent Document 1.
[0004]
[Patent Document 1]
Patent No. 3034519 (paragraphs 0023 and 0024, FIGS. 2 and 4)
[0005]
According to this cooling structure, since the compressed air for cooling impinges on the outer surface of the turbine rotor from an oblique direction, the pressure loss at the nozzle hole is slightly reduced, but the speed of the compressed air ejected from the pre-rotation nozzle is reduced. Of these, the axial component collides with the turbine rotor and causes a pressure loss, so that the pressure loss is still considerably large. In addition, a power loss occurs upstream of the pre-rotation nozzle due to a high relative speed with respect to the turbine rotor, which causes a temperature rise around the turbine rotor and a temperature rise of the cooling compressed air. Moreover, in order to provide the pre-swirl nozzle, a large radial space is required.
[0006]
Therefore, an object of the present invention is to reduce the power loss and the pressure loss by reducing the relative speed between the cooling compressed air and the rotor without requiring a large arrangement space, and to effectively reduce the cooling compressed air temperature. Another object of the present invention is to provide a gas turbine that can extend the life of the rotor by increasing the cooling efficiency of the rotor.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a gas turbine according to the present invention includes a compressor, a combustor that burns compressed air from the compressor, and a turbine that extracts power from combustion gas from the combustor. Wherein, between the compressor and the turbine, an inner casing that covers an outer periphery of a rotor and forms an inner peripheral wall of a passage of the compressed air, and while rotating the compressed air in a rotation direction of the rotor, A swirl nozzle that penetrates an inner casing and is introduced to the outer periphery of the rotor, and the rotor has compressed air introduced to the outer periphery of the rotor, and has the turbine rotor blade through a hollow portion of the rotor. An outflow hole for flowing out toward the turbine rotor is formed.
[0008]
According to this gas turbine, the compressed air from the compressor is radially introduced from the swirl nozzle to the outer periphery of the rotor, and the introduced air cools the rotor. At this time, the compressed air introduced into the rotor from the swirling nozzle rotates in the rotating direction of the rotor as a swirling flow, so that the relative speed between the compressed air and the rotor is reduced, and power loss and pressure loss are reduced. At the same time, a rise in the temperature around the rotor and a rise in the temperature of the compressed air for cooling are suppressed, and the cooling effect of the rotor is improved. Further, since the compressed air in which the temperature rise is suppressed is sent to the turbine rotor via the hollow portion of the rotor, the cooling effect of the turbine rotor having the turbine blade is improved. This makes it possible to extend the life of the entire rotor including the turbine rotor. Furthermore, since the swirl nozzle can be formed by a radial hole provided in the inner casing, the swirl nozzle can be arranged using a limited space without requiring a large arrangement space.
[0009]
In an embodiment of the present invention, a ring member is provided inside the inner casing, and the swirl nozzle is formed in the first introduction hole formed in the inner casing in a radial direction, and formed in the ring member. A second introduction hole which is inclined with respect to the radial direction and communicates with the first introduction hole. According to this configuration, the swirl nozzle can be easily formed. That is, in the case where the introduction hole for forming the swirling flow is provided directly in the direction inclined with respect to the radial direction in the large inner casing without using the ring member, it is difficult to perform the drilling operation. On the other hand, a first introduction hole in the radial direction is formed in the inner casing, and a second introduction hole extending in a direction inclined with respect to the radial direction is formed in a small ring member formed separately from the inner casing. By assembling this ring member to the inner casing, the swirl nozzle can be easily formed.
[0010]
In the embodiment of the present invention, the second introduction hole forms a speed increasing passage having a passage area on the downstream side smaller than that on the upstream side. As a result, the speed of the compressed air can be increased to near the peripheral speed of the rotor, and the static temperature of the compressed air can be reduced.
[0011]
Further, in the embodiment of the present invention, the passage of the compressed air forms a diffuser, and is located radially inward of the diffuser and closer to the upstream side of the diffuser, and a seal is provided between the inner casing and the rotor. A member is provided, and the swirl nozzle is arranged at a position corresponding to a position closer to the downstream side of the diffuser than the seal member. According to this configuration, the temperature rise of the compressed air in the space between the inner casing and the rotor is suppressed, and the rotor can be more effectively cooled. In other words, since the pressure downstream of the diffuser is higher than the pressure upstream of the diffuser, the compressed air that has exited the swirl nozzle located closer to the downstream flows back through the space and passes through the gap between the upstream end of the diffuser and the rotor. Leakage into the diffuser passage is prevented by the seal member. Here, since the seal member is located closer to the upstream side of the diffuser, the surface area of the portion of the rotor that faces the inside of the diffuser upstream of the seal member is reduced. Therefore, the friction loss with the compressed air in this portion is reduced. On the other hand, the surface area of the rotor downstream of the seal member becomes larger, but in this portion, the compressed air forms a swirling flow and the relative speed with respect to the rotor is reduced. Power loss is suppressed.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partially cutaway side view of a gas turbine according to a first embodiment of the present invention. In the figure, a gas turbine 1 compresses an introduced air IA with a compressor 2 and guides it to a combustor 3, injects gas or liquid fuel F into the combustor 3 to burn it, and obtains a high-temperature and high-pressure combustion obtained. The gas drives the turbine 4.
[0013]
In the embodiment shown in the figure, an axial flow type compressor is used as the compressor 2, and the axial flow type compressor 2 is a compressor rotor 41 a forming a front portion of a rotor 41 of a single-shaft gas turbine 1. A large number of moving blades 23 are arranged on the outer peripheral surface of the housing 24. Combination of these moving blades 23 and a plurality of stationary blades 27 arranged on the inner peripheral surface of the housing 24 compresses the air sucked from the intake cylinder 28. Then, the compressed air A is supplied to the vehicle room 29 formed in an annular shape. The rotor 41 constitutes a rotating part of the gas turbine 1, and includes, in addition to the compressor rotor 41a, a coupling rotor 41b, a turbine rotor 41r, and a rear end shaft portion 41e (FIG. 2). ing.
[0014]
A plurality of the combustors 3 are arranged at equal intervals in an annular casing 29 along the circumferential direction thereof, and the compressed air A sent to the casing 29 burns as shown by arrows a and b. While being guided into the combustion chamber 32 in the cylinder 31, the fuel F is injected into the combustor 3 from the fuel nozzle 34 into the combustion chamber 32, and the fuel F is mixed with the compressed air A and burned. The high-pressure combustion gas G is sent to the turbine 4.
[0015]
The turbine 4 includes a plurality (four in this example) of turbine rotors 41r and a turbine casing 42 that covers the outer periphery of the turbine rotor 41r. On the other hand, a plurality of stages of turbine blades 44 are provided on the turbine rotor 41r so as to be located between the turbine vanes 43 of each stage. The turbine rotor 41r and the compressor rotor 41a are connected by the coupling rotor 41b.
[0016]
As shown in FIG. 2, each turbine rotor 41r is configured by attaching a turbine rotor blade 44 to an outer periphery of a disk 45. The turbine rotor 41r of each stage has its disk 45 connected to each other by a turbine mounting bolt 46, and the disk 45 of the first stage turbine rotor 41r is connected to the rear of the coupling rotor 41b by the bolt 46. Further, the rear end shaft portion 41e is connected to the disk 45 of the last stage turbine rotor 41r by the bolt 46. The entire rotor 41 is rotatably supported by the housing 24 of FIG. 1 via front and rear bearings 61 and 62. The front bearing 61 supports a front portion of the compressor rotor 41a, and the rear bearing 62 supports a rear end shaft portion 41e in FIG.
[0017]
An inner casing 20 is provided between the compressor 2 and the turbine 4 to cover the outer periphery of the rear part of the compressor rotor 41a and the entire outer periphery of the coupling rotor 41b. A passage 21 for compressed air A is formed between the compressor 2 and the cabin 29 of the combustor 3 shown in FIG. Further, a swirling nozzle 5 is provided on the peripheral wall of the inner casing 20, and the swirling nozzle 4 causes the compressed air A to swirl in the same direction as the rotation direction of the rotor 41 as described later. 20 penetrates in the radial direction and is introduced into the outer periphery of the coupling rotor 41b.
[0018]
In this embodiment, as the swirling nozzle 5, a plurality of introduction holes 51 having a circular cross section are formed in the peripheral wall of the inner casing 20 at equal intervals in the circumferential direction. As shown in FIG. 3, each introduction hole 51 has a predetermined angle θ with respect to a radiation line C extending in the radial direction through the axis O of the rotor 41 so that the tip on the inner diameter side is directed in the rotation direction R of the rotor 41. Only inclined. A part of the compressed air A in the passage 21 is introduced as cooling air into the introduction holes 51, and a cooling space formed between the inner casing 20 and the rotor 41 through the introduction holes 51. The swirling flow D swirling in the rotation direction of the rotor 41 is ejected into the inside 40.
[0019]
The passage 21 of the compressed air A shown in FIG. 2 forms a diffuser, and the inner casing 20 and the inner casing 20 are located at upstream and downstream positions inside a cooling space 40 formed radially inward of the diffuser 21. Seal members 6 and 7 such as a labyrinth seal for sealing between the rotor 41 and the like are provided. Further, inside the cooling space 40, flanges 41af, 41bf projecting outward in the radial direction for connecting the compressor rotor 41a and the coupling 41b are provided, and bolts are provided between the flanges 41af, 41bf. B and nut N. The position between the inner casing 20 and the compressor rotor 41a is located upstream of the mounting portion of the flanges 41af, 41bf and the bolt B / nut N, that is, located radially inward of the diffuser 21 and closer to the upstream of the diffuser 21. , The seal member 6 is disposed. The downstream seal member 7 is disposed downstream of the swirl nozzle 5.
[0020]
The coupling rotor 41b of the rotor 41 has an outlet hole 55 for allowing the compressed air A introduced into the cooling space 40 from the swirl nozzle 5 to flow into the hollow portion 60 inside the rotor 41. Further, in the disk 45 of the turbine rotor 41r, an air intake hole 48 located radially inside the turbine mounting bolt 46 is provided so as to penetrate in the axial direction, and the air intake hole 48 is provided between the disks 45. A radial communication hole 47 is provided in the outer periphery of the disk 45, and a cooling air hole 49 for supplying the compressed air A from the communication hole 47 to the root portion 44a of the turbine blade 44 is formed in the outer periphery of the disk 45. ing.
[0021]
Next, the operation of the above configuration will be described. A part of the compressed air A flowing from the compressor 2 in FIG. 1 to the combustor 3 is introduced into the cooling space 40 from the swirl nozzle 5 in FIG. At this time, the compressed air A introduced from the swirl nozzle 5 to the rotor 41 is accelerated by being introduced from the large space 40 to the swirl nozzle 5 in a narrow passage as shown in FIG. The swirling flow D turns as shown in FIG. As a result, the relative speed between the compressed air A and the rotor 41 is reduced and the power loss is reduced, so that the temperature rise around the rotor is suppressed. Further, the temperature rise of the compressed air A introduced into the space 40 is also suppressed. Thereby, the cooling efficiency of the coupling rotor 41b is improved. Further, since the compressed air A becomes the swirling flow D and strikes the outer peripheral surface of the rotor 41 obliquely, the pressure loss is also reduced. Further, since the swirl nozzle 5 is provided in the inner casing 20, the swirl nozzle 5 can be arranged by effectively using a limited space without requiring a large arrangement space.
[0022]
The passage 21 for the compressed air A is a diffuser, and a space between the inner casing 20 and the rotor 41 is sealed at an upstream position inside a cooling space 40 formed radially inward of the diffuser 21. Since the seal member 6 is provided, the rotor 41 can be effectively cooled for the following reasons. That is, first, since the pressure downstream of the diffuser 21 is higher than the pressure upstream of the diffuser 21, the air that has exited the swirling nozzle 5 located closer to the downstream flows back through the cooling space 40 in the direction of arrow P. Thus, leakage from the gap 65 between the upstream end of the diffuser 21 and the rotor 41 to the diffuser 21 is prevented by the seal member 6. Here, since the seal member 6 is located on the upstream side of the diffuser 21, that is, on the front side of the front and rear central portion, the surface area of the portion of the rotor 41 that faces the inside of the diffuser 21 on the upstream side of the seal member 6 is reduced. Become smaller. Therefore, in this portion, the friction loss with the compressed air A that has entered through the gap 65 is reduced. On the other hand, the surface area of the rotor 41 on the downstream side of the seal member 6 becomes larger, but in this portion, the compressed air A becomes the swirling flow D and the relative speed with respect to the rotor 41 decreases, so that the power of the rotor 41 Loss is suppressed. Thus, in the space 40 between the front and rear seal members 6 and 7, the outer peripheral walls of the compressor rotor 41a and the coupling rotor 41b and the flanges 41af and 41bf are effectively cooled by the compressed air A for cooling.
[0023]
The compressed air A for cooling, in which the rise in temperature is suppressed and introduced into the cooling space 40, is supplied from the outflow hole 55 to the hollow portion 60 inside the rotor 41, and then the air is taken into the rear turbine rotor 41r. The air is supplied from the cooling air hole 49 to the root portion 44a of the turbine blade 44 via the hole 48 and the communication hole 47, and the turbine blade 44 is cooled effectively. At this time, since the sealing members 6 and 7 for sealing between the inner casing 20 and the rotor 41 are arranged at the upstream and downstream positions inside the cooling space 40, the compressed air in the cooling space 40 is compressed. A smoothly flows out of the outflow hole 55 and is used for cooling the turbine blade 44. As described above, the compressor rotor 41a, the coupling rotor 41b, and the turbine rotor 41r are effectively cooled, so that the life of the rotor 41 as a whole is extended.
[0024]
FIG. 4 is a longitudinal sectional view showing the swirling nozzle 5 according to the second embodiment, and FIG. 5 is a transverse sectional view of a main part thereof. In this embodiment, as the swirling nozzle 5, a first introduction hole 52 formed of a circular hole extending in the radial direction is formed in the inner casing 20, and a ring member 53, which is a separate member, is formed inside the inner casing 20. Is mounted in an embedded manner, and the ring member 53 communicates with the first introduction hole 52, and the tip is inclined toward the rotation direction R of the rotor 41, as in the case of the first embodiment. In addition, a second introduction hole 54 that jets out as a swirling flow D around the rotor 41 is formed. The second introduction hole 54 is formed such that the passage area on the downstream side (inner diameter side) is smaller than the passage area on the downstream side (inner diameter side) with respect to the upstream side (outer diameter side), and serves as a speed increasing passage. The ring member 53 is, for example, divided into two parts in the circumferential direction to facilitate the fitting into the inner peripheral surface of the rotor 41.
[0025]
According to the second embodiment, the swirl nozzle 5 can be easily formed. That is, as shown in FIGS. 2 and 3, when the introduction hole 52 whose tip is inclined in the rotation direction R of the rotor 41 is provided directly in the inner casing 20 without using the ring member 53, Since 20 is large, drilling work is troublesome. On the other hand, a first introduction hole 52 in the radial direction is formed in the inner casing 20 shown in FIG. 5, and the second introduction hole 54 is formed in a small ring member 53 separate from the inner casing 20. By attaching the ring member 53 to the inner casing 20, the swirl nozzle 5 can be easily formed.
[0026]
In addition, by using the ring member 53, the inclination angle θ of the second introduction hole 54 can be freely set to adjust the swirling speed of the swirling flow D, the temperature of the cooling air, and the like. Effective cooling can be performed. That is, since the inclination angle θ can be made large, the loss due to friction with the surface of the rotor 41 after the ejection of the compressed air A is reduced, and the swirling speed (circumferential speed component) of the swirling flow D is kept high. The static temperature of the compressed air A can be effectively reduced with a small pressure loss. In addition, since the second introduction hole 54 that forms the main part of the nozzle flow path is provided in the small ring member 53, the processing is easy. Therefore, the processing error can be reduced and the quality can be improved. Further, as shown in FIG. 5, if the second introduction hole 54 is formed in a tapered shape in which the downstream side is narrowed, the ejection speed of the compressed air A from the swirl nozzle 5 increases, and a higher-speed swirl flow D is generated. Since the static temperature of the compressed air A is reduced, the cooling effect of the compressor rotor 41a, the coupling rotor 41b, and the turbine rotor 41r shown in FIG. 2 is further enhanced.
[0027]
In the first embodiment as well, by forming the introduction hole 51 of FIG. 3 in a tapered shape, the temperature of the cooling compressed air A in the space 40 can be reduced, and the cooling effect of the rotor 41 can be enhanced.
[0028]
【The invention's effect】
As described above, according to the gas turbine of the present invention, the power loss is reduced by reducing the relative speed between the compressed air for cooling and the rotor without requiring a large arrangement space, and the compressed air for cooling is reduced. The temperature can be effectively reduced, thereby increasing the cooling efficiency of the rotor and extending the life of the rotor.
[Brief description of the drawings]
FIG. 1 is a partially cutaway side view of a gas turbine according to an embodiment of the present invention.
FIG. 2 is an enlarged longitudinal sectional view showing a main part of the gas turbine.
FIG. 3 is a cross-sectional view of the main part.
FIG. 4 is a longitudinal sectional view showing a second embodiment of the present invention.
FIG. 5 is a transverse sectional view of a main part of FIG.
[Explanation of symbols]
2 Compressor 3 Combustor 4 Turbine 5 Swirling nozzle 20 Inner casing 21 Compressed air passage (diffuser)
41 ... rotor 41r ... turbine rotor 44 ... turbine blade 60 ... hollow part 51 ... introduction hole 52 ... first introduction hole 53 ... ring member 54 ... second introduction hole 55 ... outflow hole A ... compressed air D ... swirl flow G ... Combustion gas

Claims (4)

A gas turbine including a compressor, a combustor that burns compressed air from the compressor, and a turbine that extracts power from combustion gas from the combustor,
Between the compressor and the turbine, an inner casing that covers an outer periphery of a rotor and forms an inner peripheral wall of the passage of the compressed air,
A swirling nozzle that penetrates an inner casing and is introduced into the outer periphery of the rotor while rotating the compressed air in a rotation direction of the rotor,
A gas turbine, wherein an outlet hole is formed in the rotor to allow compressed air introduced to the outer periphery of the rotor to flow through a hollow portion of the rotor toward a turbine rotor having the turbine blade. 2. The device according to claim 1, further comprising a ring member mounted inside the inner casing, wherein the swirling nozzle is provided with a first introduction hole formed in the inner casing and extending in a radial direction, and a first introduction hole formed in the ring member. A gas turbine having a second inlet hole inclined with respect to a radial direction communicating with the inlet hole. 3. The gas turbine according to claim 2, wherein the second introduction hole forms a speed increasing passage having a passage area on the downstream side smaller than that on the upstream side. 4. The compressed air passage according to claim 1, wherein the compressed air passage forms a diffuser, and is located radially inward of the diffuser and closer to the upstream side of the diffuser, between the inner casing and the rotor. 5. A gas turbine, wherein the swirl nozzle is disposed at a position corresponding to a position closer to the downstream side of the diffuser than the seal member.

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