JP2006132425A - Scroll with heat transfer facilitating rib of gas turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scroll with heat transfer facilitating ribs of a gas turbine reducing a cost by a simple construction and obtaining high cooling efficiency for the scroll. <P>SOLUTION: The scroll 4 whirls combustion gas G from a combustor 2 in the gas turbine about a rotation axis C and introduces it to the turbine 3. The scroll is formed on an outer peripheral surface with the heat transfer facilitating ribs 6A, 6B, 6C for facilitating cooling through heat transfer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a scroll of a gas turbine, and more particularly to a scroll with a heat transfer promoting rib excellent in scroll cooling efficiency.

  Conventionally, a so-called single can combustor type gas turbine among gas turbines is advantageous in terms of cost as compared with a multi-can combustor type gas turbine, and is therefore widely used in medium and small gas turbines. However, the combustion gas emitted from one combustor must be circulated by a scroll so as to flow uniformly with respect to the first stage turbine nozzle. Therefore, the scroll is exposed to the hottest combustion gas as the part downstream from the combustor, and is the part having the largest area exposed to the combustion gas. Therefore, a sufficient cooling structure is required for scrolling.

As an example of the convection cooling for the scroll, there is a gas turbine scroll having an improved air flow structure for scroll cooling (see, for example, Patent Document 1). That is, the scroll of the gas turbine includes a scroll body that forms a space in which high-temperature combustion gas supplied from a combustor flows, and a scroll that is provided so as to surround the scroll body at a predetermined distance from the scroll body. A flow path through which compressed air from the compressor flows is formed between the housing and the housing in a state suitable for convection cooling.
JP-A-11-303648

  However, sufficient cooling of the scroll body cannot be expected even with this convection cooling type scroll.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a scroll with a rib for heat transfer enhancement of a gas turbine that can provide a high cooling efficiency for the scroll by reducing the manufacturing cost only by adding a simple structure to the scroll of the gas turbine. It is in.

  In order to achieve the above object, a scroll with a heat transfer enhancement rib of a gas turbine according to the present invention is a scroll that guides combustion gas from a combustor in the gas turbine to the turbine while turning around the rotation axis. And the heat transfer promotion rib which accelerates | stimulates the cooling by heat transfer is provided in the outer surface.

  According to this configuration, when compressed air from the compressor flows on the outer surface of the scroll, the turbulence of the compressed air is strongly disturbed by the heat transfer promotion rib provided on the outer surface of the scroll. As a result, heat transfer on the outer surface of the scroll increases, so that heat is effectively removed from the outer surface of the scroll and the scroll is cooled. Thereby, the temperature rise of a scroll can be suppressed and the durability of a scroll improves. Moreover, since the cooling effect with respect to a scroll is acquired with the very simple structure of attaching a heat-transfer acceleration | stimulation rib to a scroll, it can apply easily and cheaply also to the existing gas turbine.

  In a preferred embodiment of the present invention, the heat transfer promoting ribs are provided on the inner peripheral surface and the rear surface of the scroll in the vicinity of the connecting portion with the combustor along the radiation surface including the rotation axis.

  According to this configuration, the heat is transmitted to the inner peripheral surface of the scroll that becomes the highest temperature due to the introduction of the combustion gas from the combustor, and to the rear surface that also becomes high temperature because the combustion gas hitting the inner peripheral surface changes its direction. Since the heat promotion rib is provided, the inner peripheral surface and the rear surface are efficiently cooled. In addition, while the inner peripheral surface and the rear surface are in contact with compressed air flowing around the rotation axis of the gas turbine, the heat transfer promoting ribs are provided along the radiation surface including the rotation axis. The compressed air collides with the heat transfer promoting ribs at a right angle or a right angle. Thereby, the cooling efficiency of the inner peripheral surface and the rear surface is improved.

  In a preferred embodiment of the present invention, the heat transfer promoting rib is provided in a circular arc shape concentric with the rotation axis in the vicinity of the connecting portion with the combustor on the front surface of the scroll.

  In the vicinity of the connecting portion with the combustor on the front surface of the scroll, the compressed air flows in a substantially radial direction toward the combustor. According to this configuration, the heat transfer promoting rib is the same as the rotation axis. Since it is provided in a circular arc shape of the core, the compressed air collides with the heat transfer promoting rib at a right angle or an angle close to a right angle. Thereby, the cooling efficiency of a scroll improves.

  In a preferred embodiment of the present invention, the heat transfer promoting rib is further pressed against the outer surface of the scroll by a pressing piece having one end joined to the scroll and the other part fixed to the scroll.

  According to this configuration, one end of the heat transfer promoting rib is joined, and the other part including the other end is in a free state and is only pressed against the outer surface of the scroll by the pressing piece. The heat transfer promotion ribs are formed of different materials, and even if there is a difference in thermal expansion between the scroll and the heat transfer promotion ribs, the heat transfer promotion ribs receiving the heat from the scroll are relatively Since there is relief when the heat is extended, an excessive stress is not generated at the joined one end portion, and the heat transfer promoting rib is not dropped from the scroll.

  According to the scroll with heat transfer enhancement ribs of the gas turbine of the present invention, the cooling effect for the scroll can be obtained with a simple structure in which the heat transfer enhancement ribs are attached to the scroll. Applicable to.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a main part of a gas turbine provided with a scroll with a heat transfer promoting rib of the gas turbine of the present invention. The gas turbine shown in the figure is provided with a centrifugal compressor 1 that generates compressed air A and behind it (on the right side in FIG. 1). A combustor 2 that generates combustion gas G, a turbine 3 driven by the combustion gas G, and a scroll 4 that guides the combustion gas G from the combustor 2 to the turbine 3 while swirling around a rotation axis C. have. The scroll 4 is manufactured by bending a plate material, and the compressed air A from the compressor 1 is introduced into a passage between the scroll 4 and the scroll housing 15. The combustor 2 is disposed in the upper part of the gas turbine, and an inner cylinder 20 forming a combustion chamber is covered with a combustor housing 22, and the compressed air A is interposed between the inner cylinder 20 and the combustor housing 22. Is formed in the inner cylinder 20. The turbine 3 is a three-stage type. A diffuser 12 is disposed downstream of the compressor 1 (outward in the radial direction).

  As shown in the front view of FIG. 2, the combustor 2 is of a single can type, is disposed on the upper part of the gas turbine at a position eccentric from the rotation axis C of the gas turbine, and extends in a substantially vertical direction. The inner cylinder 20 forming the chamber is covered by the combustor housing 22, and an air passage 24 for introducing the compressed air A into the inner cylinder 20 is formed between the inner cylinder 20 and the combustor housing 22. . On the outer surface of the scroll 4, a heat transfer promoting rib 6 </ b> A is provided on the front surface 4 a in the vicinity of the connecting portion 40 with the combustor 2, that is, on the outer surface of the front wall 41 near the compressor 1 (FIG. 1). It has been. The heat transfer promotion ribs 6A are formed in an arc shape concentric with the rotation axis C, and in this example, 10 are provided. As will be described later, one end 60 of the heat transfer promoting rib 6A is joined to the scroll 4, and the other part is pressed against the front surface 4a by a plurality of pressing pieces 8 extending in the radial direction. Further, a flange 7 for supporting the scroll 4 on the diffuser base 12a of FIG. 1 is attached to the outer peripheral portion of the front surface 4a of the scroll 4. A radially outer side and a rear side of the scroll 4 are covered with a scroll housing 15 that forms a part of the housing of the entire gas turbine.

  As shown in FIG. 3, the outer surface of the scroll 4 is transmitted to the rear surface 4b and the inner peripheral surface 4c in the vicinity of the connecting portion 40 with the combustor 2, that is, to the outer surfaces of the rear wall 42 and the inner peripheral wall 43, respectively. Heat promotion ribs 6B and 6C are provided. These heat transfer promotion ribs 6B and 6C are provided along the radiation surface S (see FIG. 2) including the rotation axis C. A plurality of heat transfer promotion ribs 6B on the rear surface 4b extend in the radial direction along the curved surface of the rear surface 4b, and the heat transfer promotion ribs 6C on the inner peripheral surface 4c extend in the axial direction parallel to the rotation axis C. A plurality are provided. One end portion 60 of the heat transfer promoting rib 6C is joined to the scroll 4, and the other portion is pressed against the inner peripheral surface 4c by a plurality of pressing pieces 8 extending in the circumferential direction. As shown in FIG. 4, the heat transfer promoting rib 6B on the rear surface 4b is joined to the scroll 4 at one end 60 which is the outermost end in the radial direction at a position close to the connecting portion 40 with the combustor 2. This portion is pressed against the rear surface 4b by a plurality of presser pieces 8 extending in the circumferential direction shown in FIG.

  2 are provided in the axial center C1 of the combustor 2, that is, the center of the flow path of the combustion gas G from the combustor 2 to the scroll 4, and the inner peripheral wall 43 of the scroll 4. It includes a position Q where the inner surface intersects, and extends in the circumferential direction on the left and right sides of the scroll 4 over almost ¼ circumference. The region where the heat transfer promoting rib 6C is provided on the inner peripheral surface 4c of FIG. 3 is also at the same circumferential position as the heat transfer promoting rib 6A. The region of the rear surface 4b where the heat transfer promoting rib 6B is provided includes the intersection position Q (FIG. 2), and extends substantially 左右 circumference in the left and right circumferential directions.

  The heat transfer promotion ribs 6A, 6B, and 6C shown in FIGS. 2 and 3 are all portions that become high temperature in the scroll 4, but other portions that are not shown are also portions that become high in the scroll 4. If present, these heat transfer promoting ribs 6A, 6B, and 6C may be provided similarly.

  A method for attaching the heat transfer promoting ribs 6A, 6B, 6C to the outer surface of the scroll 4 will be described with reference to FIG. The other heat transfer promotion ribs 6B and 6C are attached in the same manner. As shown in the figure, the heat transfer promoting rib 6A having a substantially quadrangular (square or rectangular) cross-sectional shape is disposed at a predetermined position on the outer surface of the scroll 4, and only one end 60 is attached to the outer surface of the scroll 4 by welding W1. Join. The other part of the heat transfer promoting rib 6A is kept in a free state where it is not joined to the scroll 4, and this free part is pressed against the outer surface of the scroll 4 by a plurality of presser pieces 8. The presser piece 8 has an elongated plate shape, and a central portion in the longitudinal direction serves as a presser portion 10 for the heat transfer promoting rib 6A. The cross-sectional shape of the pressing portion 10 is U-shaped, and is substantially the same as the cross-sectional shape and dimensions of the heat transfer promoting rib 6A. Both sides of the pressing piece 8 across the pressing portion 10 are joined to the outer surface of the scroll 4 by welding W2. The material of each member is, for example, a cobalt alloy in which the scroll 4 is excellent in high-temperature creep strength, and the heat transfer promotion rib 6A and the presser piece 8 are a nickel alloy that is less expensive than the cobalt alloy.

  In this way, the heat transfer promoting rib 6A is joined to the scroll 4 because the one end 60 is joined and the other part is free and is only pressed against the outer surface of the scroll 4 by the presser piece 8. Even if the heat promotion rib 6A is formed of a different material as described above and there is a difference in thermal expansion between the scroll 4 and the heat transfer promotion rib 6A, the heat transfer promotion rib 6A that receives the heat from the scroll 4 is the scroll 4. When the heat is extended relatively in the direction of the arrow B, it is not restrained. Therefore, an excessive stress is not generated in the joined one end portion 60, thereby preventing the heat transfer promoting rib 6A from falling off the scroll 4. Moreover, since the heat | fever extension with respect to the scroll 4 of the pressing piece 8 can be absorbed by the deformation | transformation of the U-shaped pressing part 10, the excessive stress by thermal expansion does not generate | occur | produce in the welding part W2.

  Next, the best mounting conditions for mounting the heat transfer promoting rib 6A to the outer surface of the scroll 4 will be described with reference to FIG. As shown in the figure, when two heat transfer promoting ribs 6A, 6A are attached to the outer surface of the scroll 4 by the mounting means, the height of the heat transfer promoting rib is e, and between the heat transfer promoting ribs 6A, 6A. Is P, and the height of the flow path corresponding to the gap between the scroll 4 and the scroll housing 15 is H. According to heat transfer theory, a good range of heat transfer efficiency, that is, a good range of cooling effect and flow path resistance is P / e = 7.5 to 10, e / H = 0.08 to 0.1. Therefore, when the heat transfer promoting rib 6A is attached to the outer surface of the scroll 4, a large cooling effect of the scroll 4 by the heat transfer promoting rib 6A can be obtained while suppressing the flow path resistance by matching the above conditions. . In the embodiment shown in FIGS. 1 to 4, the heat transfer promotion ribs 6 </ b> A, 6 </ b> B, and 6 </ b> C are provided so as to satisfy the above conditions. In addition, you may use the wire etc. of the circular cross section which can be obtained easily as a heat-transfer promotion rib. Moreover, when the heat transfer promotion rib becomes long and attachment becomes difficult, it may be divided into a plurality along the length direction.

  Next, the operation of the above configuration will be described. As shown in FIG. 1, the compressed air A generated by the compressor 1 flows into the scroll housing 15 through the diffuser 12 and is guided to the outer peripheral surface 4 d of the outer peripheral wall 44 of the scroll 4. Into the second air passage 24. On the other hand, in the combustor 2, the fuel and the compressed air A are mixed and burned, and the high-temperature combustion gas G is guided into the scroll 4. At this time, in the scroll 4, the combustion gas G goes to the front wall 41 after going to the inner peripheral wall 43 and the rear wall 42 of the scroll 4, and therefore, among the outer surfaces of the scroll 4, the inner peripheral surface 4 c, the rear surface 4 b, and the front surface 4 a. And become hot.

  Since the heat transfer promoting ribs 6A, 6B, 6C are provided on the front surface 4a, the rear surface 4b, and the inner peripheral surface 4c, the disturbance of the compressed air A flowing along the outer surface of the scroll 4 is promoted. As a result, heat transfer between the outer surface of the scroll 4 and the compressed air A increases, and as a result, heat is effectively removed from the outer surface of the scroll 4 by the compressed air A, and the scroll 4 is cooled.

  Here, the compressed air A flowing into the scroll housing 15 from the compressor 1 through the diffuser 12 flows around the rotation axis C as shown by an arrow A1 in FIG. The compressed air A1 comes into contact with the rear surface 4b and the inner peripheral surface 4c. On the other hand, since the heat transfer promotion ribs 6B and 6C are provided on the rear surface 4b and the inner peripheral surface 4c along the radiation surface S (FIG. 2) including the rotation axis C, the compressed air A1 is transferred to the heat. It collides with the promotion ribs 6B and 6C at a right angle or an appropriate angle θ close to a right angle. Thereby, the cooling efficiency of a scroll improves.

  On the other hand, on the front surface 4a of the scroll 4, since the compressed air A1 wraps around toward the combustor 2, the compressed air is almost radially emitted in the vicinity of the connecting portion 40 with the combustor 2 as shown by an arrow A2 in FIG. Flowing into. On the other hand, since the heat transfer promoting rib 6A is provided on the front surface 4a in an arc shape concentric with the rotation axis C, the compressed air A2 is perpendicular to the heat transfer promoting rib 6A or has a large collision angle θ. Collide with. Thereby, the cooling efficiency of a scroll improves.

  As a result, the scroll 4 is effectively cooled by the heat transfer promotion ribs 6A, 6B, 6C provided in the high temperature portion of the scroll 4, so that the temperature rise of the scroll 4 can be suppressed and the durability of the scroll 4 is improved. Moreover, since the cooling effect with respect to the scroll 4 can be obtained with a very simple structure in which the heat transfer promoting ribs 6A, 6B, and 6C are attached to the scroll 4, it can be easily and inexpensively applied to an existing gas turbine.

It is a longitudinal cross-sectional view of the gas turbine which attached the scroll with a heat-transfer acceleration | stimulation rib which concerns on this invention. It is a front view of a scroll. It is the perspective view which looked at the rear surface of the scroll from diagonally downward. It is the perspective view which looked at the rear surface of the scroll from diagonally upward. . It is a schematic diagram explaining attachment of the heat-transfer promotion rib to a scroll. It is a schematic diagram for demonstrating the optimal attachment conditions of the heat-transfer acceleration | stimulation rib with respect to a scroll.

Explanation of symbols

2 Combustor 3 Turbine 4 Scroll 5 Connection 6A, 6B, 6C Heat transfer promotion rib 8 Presser piece 9 Welded part

Claims (4)

A scroll that guides combustion gas from a combustor in a gas turbine to the turbine while swirling around the rotation axis;
A scroll with a heat transfer enhancement rib of a gas turbine, wherein a heat transfer enhancement rib for promoting cooling by heat transfer is provided on an outer surface.   2. The gas turbine according to claim 1, wherein the heat transfer promotion rib is provided on the inner peripheral surface and the rear surface of the scroll in the vicinity of the connection portion with the combustor along the radiation surface including the rotation axis. Scroll with heat transfer promoting ribs.   3. The heat transfer enhancement of the gas turbine according to claim 1 or 2, wherein the heat transfer promotion rib is provided in an arc shape concentric with the rotation axis at a portion in the vicinity of the connecting portion with the combustor on the front surface of the scroll. Ribbed scroll. 4. The gas turbine according to claim 1, wherein one end of the heat transfer promoting rib is joined to the scroll and the other part is pressed against an outer surface of the scroll by a pressing piece fixed to the scroll. Scroll with heat transfer promoting ribs.

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