Combustion section with outer shell shield

Abstract

The invention relates to a combustion section (01) of a gas turbine (02), comprising an annular combustion chamber (07), a combustor arrangement (08) upstream of the combustion chamber (07), an annular compressor diffuser (15) and an annular combustion casing (11). The combustion casing (11) has an outer section wall (12) and an upstream section wall (13) as well as an inner section wall (14). The inner section wall (14) extends along the rotor axis and is arranged between the combustor arrangement (08) and the compressor diffuser (15). In order to improve the thermal protection of the combustion casing (11), the inner section wall (14) is attached on the side facing the rotor axis with a shield (21) with at least a free space between the shield and the inner section wall. Thus, the outer diffuser wall of the compressor diffuser extends in axial direction up to the upstream half of the shield (21).

Description

[0001] The present invention relates to a combustion section of a gas turbine, the combustion section comprising an annular combustion chamber and an annular combustion shell, wherein the combustion shell comprises different sections having means for preventing rapid temperature changes.

[0002] Gas turbines with annular combustion chambers are known in the prior art. In a typical arrangement, the combustion casing is located outside the combustion chamber. Furthermore, depending on the arrangement of the combustion chamber relative to the flow passages, compressor, and expander turbine, the combustion casing also includes an upstream section located upstream of the combustion chamber and extending radially. To obtain sufficient rigidity and to secure the combustion chamber, another inner section of the combustion casing is arranged closer to the rotor axis, which extends axially from the radially inner end of the upstream section. Due to its location, the inner section is traversed by compressed air and is further heated due to its proximity to the combustion chamber. This results in thermal expansion of the inner section, particularly leading to thermal stress during gas turbine startup.

[0003] To avoid critical stresses at various components of the gas turbine, the startup process is slowed down or additional cooling features are applied.

[0004] The objective of this invention is to simplify the cooling features and thereby enable the gas turbine to start up quickly.

[0005] This task is accomplished by the combustion section described in the main aspects of the invention. Advantageous solutions are the subject of other aspects of the invention.

[0006] The general-purpose combustion section is intentionally part of the gas turbine. Therefore, the gas turbine defines a rotor shaft and has an upstream side and a downstream side. The gas turbine also includes a compressor section arranged upstream of the combustion section and an expansion turbine section arranged downstream of the combustion section.

[0007] Each combustion section includes a combustion chamber. Here, the combustion chamber is an annular combustion chamber surrounding the rotor axis. In addition, the combustion section includes a burner assembly with several burners distributed circumferentially upstream of the combustion chamber.

[0008] Downstream of the compressor section of the gas turbine, an annular compressor diffuser is arranged at least partially within the combustion section. The compressor diffuser includes an annular inner diffuser wall and an annular outer diffuser wall defining a flow passage through the compressor diffuser. Here, the end portion of the outer diffuser wall located downstream of the outer diffuser wall is further relevant to the present invention.

[0009] The combustion section also includes an annular combustion shell that at least partially surrounds the annular combustion chamber. Here, the combustion shell has an outer section wall, an upstream section wall, and an inner section wall. The outer section wall extends along the rotor axis and is arranged radially outward relative to the combustion chamber. The upstream section wall extends radially inward from the upstream end of the outer section wall and is therefore arranged upstream relative to the combustion chamber. In a typical solution, the burner assembly penetrates the upstream section wall; however, it is also possible that the burner assembly is covered by the combustion shell and is therefore located downstream of the upstream section wall. The inner section wall extends along the rotor axis from the radially inner end of the upstream section wall. Here, the inner section wall is located between the radially outer burner assembly and the radially inner compressor diffuser.

[0010] Therefore, the outer diffuser wall at least partially overlaps the inner section wall in the axial direction. Thus, the wall end is located in the axial direction between the downstream end of the upstream section wall and the downstream end of the inner section wall.

[0011] To protect the combustion chamber from thermal stress, a shield is installed within it. Although the combustion chamber imposes a high thermal load on the components of the combustion chamber, the shield is positioned on the inner section wall facing the rotor axis. It is necessary to maintain the free space between the shield and the inner section wall at least half the length of the inner section wall. Therefore, the end of the outer diffuser wall needs to be axially positioned between the upstream end and the middle of the shield. Thus, the compressed air flow first passes through the outer diffuser wall and then further through the shield.

[0012] It is important to note that it is unnecessary for the shielding to have no contact with the internal segment wall or for the free space to be continuous along the entire length of the shielding. Firstly, attachment devices can be used to attach the shielding to the internal segment wall. Secondly, at the beginning and / or end of the shielding, the free distance between the internal segment wall and the shielding can be reduced to zero.

[0013] By arranging shielding elements on the inner side of the internal section wall, the displacement of compressor section components can be modified, especially during gas turbine startup. In this way, thermal stress is significantly reduced compared to the general solution without shielding elements on the inner side of the internal section wall.

[0014] To achieve the improvements caused by the shielding, it is unnecessary to also place a shielding at the upstream section wall. Instead, it is advantageous that there is an axial distance between the upstream end of the shielding and the radially inner end of the upstream section wall.

[0015] In principle, there are two possibilities for achieving free space (or a combination thereof) between the shield and the inner segment wall. First, spaced-apart shields can be attached to the inner segment wall, which has a continuous inner surface, such as a cylindrical radially inner surface, on its inner side facing the rotor axis. However, it is advantageous to arrange recesses on the radially inner side of the inner segment wall. Therefore, the shield is specifically arranged within the recesses such that the radially inner sides of the inner segment wall upstream and downstream of the shield, and further, the radially inner side of the shield, form a continuous, smooth inner surface.

[0016] If a recess is given, the bottom surface of the recess is the radially inner side of the inner segment wall within the shielding area. If the radially inner side is mentioned together with the shielding, the inner segment wall located in the same axial position as the shielding relative to the inner side of the inner segment wall refers to the conventional inner segment wall.

[0017] The radial free space between the shield and the inner section wall should be sufficiently large to achieve the thermal protection feature. Therefore, it is advantageous that the free space (free distance) between the shield and the radially inner side of the inner section wall is at least 0.1 times the thickness of the arrangement structure from the radially outer side of the inner section wall to the radially inner side of the shield. Particularly advantageous here is that the free distance is at least 0.15 times the thickness of the arrangement structure. (Where the free distance and thickness are determined at the same axial location.)

[0018] To keep the dimensions of this arrangement within a useful range, a small free space should be maintained. Therefore, it is advantageous that the free distance between the radially outer side of the shield and the radially inner side of the inner section wall is at most 0.3 times the thickness of the arrangement from the radially outer side of the inner section wall to the radially inner side of the shield. Particularly advantageous here is that the free space is at most 0.2 times the thickness of the arrangement.

[0019] Optimizing the free space based on the relative position of the outer diffuser wall is more advantageous. Here, it is advantageous that the free distance between the radially outer side of the shield and the radially inner side of the inner section wall is at least 0.5 times the distance from the shield to the outer diffuser wall. It is also particularly advantageous that the free distance is at least 0.7 times the distance between the shield and the outer diffuser wall.

[0020] On the other hand, it is advantageous that the free distance between the radially outer side of the shield and the radially inner side of the inner section wall is at most 1.5 times the distance from the shield to the outer diffuser wall. It is also particularly advantageous that the free distance is at most 0.9 times the distance between the shield and the outer diffuser wall.

[0021] If an inner cover is attached to the outside of the inner section wall, it is advantageous to further prevent rapid heat transfer to the combustion chamber, especially to the inner section wall. Therefore, the inner cover is arranged opposite to the shield at the inner section wall. Here, it is necessary to have an inner gap between the inner cover and the inner section wall.

[0022] Since there are fewer space issues on the outer side of the inner segment wall, the inner cover can be attached to the inner segment wall. More advantageously, to seal the inner gap on the downstream side, the inner cover includes a bend facing the inner segment wall. Here, it is particularly advantageous that the bend contacts the inner segment wall.

[0023] Regarding the shielding element and the free space, preferably, the inner gap has a width between the inner section wall and the inner cover (without bends) that is approximately the size of the free space between the radially outer side of the shielding element and the radially inner side of the inner section wall. Advantageously, the width is at least 0.6 times and at most 1.5 times the free distance. Particularly advantageously, the width is at least 0.8 times and at most 1.2 times the free distance.

[0024] Similarly, if an upstream cover is attached to the downstream side of the upstream section wall, it is advantageous to prevent rapid heat transfer to the combustion shell, especially to the upstream section wall. Here, an upstream gap is necessary between the upstream cover and the upstream section wall.

[0025] Since there are fewer space issues on the downstream side of the downstream section wall, the upstream cover can be attached to the upstream section wall. More advantageously, to close the upstream gap radially outward, the upstream cover includes a bend facing the upstream section wall. Here, it is particularly advantageous that the bend contacts the upstream section wall.

[0026] Regarding the shielding element and the free space, it is preferable that the upstream gap has a width approximately equal to the dimension of the free space between the radially outer side of the shielding element and the radially inner side of the inner section wall between the upstream section wall and the upstream cover (without bends). Advantageously, the width is at least 0.6 times and at most 1.5 times the free distance. Particularly advantageously, the width is at least 0.8 times and at most 1.2 times the free distance.

[0027] To optimize thermal protection of the combustion shell at the edge between the upstream section wall and the inner section wall, it is more advantageous to connect the upstream cover to the inner cover. With this solution, a continuous gap from the inner gap to the upstream gap can be achieved through the protective distance between the inner and upstream covers and the inner and upstream section walls.

[0028] The following figures illustrate an exemplary solution for using a shield at the combustion casing.

[0029] Figure 1 A schematic sketch of a gas turbine is shown;

[0030] Figure 2 An example of a creatively designed combustion section is shown;

[0031] Figure 3 It shows according to Figure 2 The arrangement structure of the shielding and covering parts at the combustion shell.

[0032] exist Figure 1 The diagram shows a schematic sketch of a gas turbine 02, which has a compressor section 06 on its upstream side 03 and an expansion turbine section 09 on its downstream side 04. A combustion section 01 is positioned between the compressor section and the expansion turbine section. Here, the combustion section 01 includes an annular combustion chamber 07. A burner assembly 08 is attached to the upstream side 03 of the combustion section 07, which includes a plurality of burners distributed in a circumferential direction. The combustion chamber 07 is covered by a combustion shell 11, which is penetrated by the burners of the burner assembly 08.

[0033] exist Figure 2 An exemplary design for a creative combustion section 01 is shown. A combustion chamber 07 extends about a rotor axis. The burner of a burner assembly 08 is located upstream of the combustion chamber 07. In this exemplary solution, the combustion shell 11 is constructed of an outer section wall 12, an upstream section wall 13, and an inner section wall 14. The outer section wall 12 is arranged radially outward of the combustion chamber 07, the upstream section wall 13 is arranged upstream of the combustion chamber 07 and penetrated by the burner of the burner assembly 08, and the inner section wall 14 is arranged radially inward relative to the burner assembly 08.

[0034] The combustion section also includes a compressor diffuser 15, which is attached to the downstream side of the compressor section 06 and is located on the side facing the rotor axis relative to the inner section wall 14. In this arrangement, the diffuser is constructed of an outer diffuser wall 16 on the radially outer side of the compressor diffuser 15 and an inner diffuser wall 19 on the radially inner side of the compressor diffuser 15.

[0035] This invention can be achieved through Figure 3The detailed view further explains this. As shown, a shield 21 is attached to the inner segment wall 14, with free space between the inner segment wall 14 and the shield 21. In this exemplary solution, the free space 22 is achieved by a recess 22. To achieve a smooth inner surface between the shield 21 upstream and downstream of the inner segment wall 14, as shown in the figure, the shield 21 is arranged within the recess 22. This recess creates a free distance 24 between the radially inner side of the inner segment wall 14 and the radially outer side of the shield 21—relative to the same axial position.

[0036] The arrangement having an inner segment wall 14 and a shield 21 defines a thickness 23 of the arrangement from the radially inner side of the shield 21 to the radially outer side of the inner segment wall 14 at the location of the shield 21. In this exemplary solution, approximately one-quarter of the free distance 24 of the thickness 23 of the arrangement is used.

[0037] Next, we can see the wall end 18 of the outer diffuser wall 16, which is positioned in the axial direction between the upstream end of the shield 21 and the middle of the shield 21. As shown in the figure, the distance from the wall end 18 to the shield 21 is approximately the same as the free distance 24.

[0038] As a further improvement, an inner cover 25 is arranged radially outward on the inner section wall 14, and an upstream cover 28 is arranged downstream on the upstream section wall 13. An inner gap 26 is applied to the inner cover 25, and an upstream gap 29 is applied to the upstream cover 28 to protect the combustion shell 11, particularly at the corner between the upstream section wall 13 and the inner section wall 14, to prevent rapid thermal expansion caused by the start-up of the gas turbine 02. As a further option, bends 27 and 30 are arranged at both covers 25 and 28, each contacting the corresponding section wall 13 or 14.

Claims

1. A combustion section (01) of a gas turbine (02), the gas turbine (02) having a rotor shaft and an upstream side (03) and a downstream side (04) and including a compressor section (06), the combustion section (01), and an expansion turbine section (09), the combustion section (01) comprising: - Annular combustion chamber (07), and - A burner assembly (08), said burner assembly (08) being located upstream of the combustion chamber (07), and - An annular compressor diffuser (15), the annular compressor diffuser (15) being located downstream of the compressor section (06), the annular compressor diffuser (15) having an inner annular diffuser wall (19) and an outer annular diffuser wall (16), the outer annular diffuser wall (16) having a wall end located on the downstream side, and - An annular combustion shell (11) having an outer section wall (12), an upstream section wall (13), and an inner section wall (14), the outer section wall (12) extending along the rotor axis and arranged radially outward relative to the combustion chamber (07), the upstream section wall (13) extending radially and arranged on the upstream side relative to the combustion chamber (07), and the inner section wall (14) extending along the rotor axis and arranged between the burner assembly (08) and the compressor diffuser (15). The outer diffuser wall (16) and the inner segment wall (14) partially overlap in the axial direction. Its features are, The inner section wall (14) has a shield (21) attached to the side facing the rotor axis, and there is a free space between the shield (21) and the inner section wall (14) that is at least half the length of the inner section wall (14), wherein the end of the wall is arranged in the axial direction between the upstream end and the middle of the shield (21).

2. The combustion section (01) according to claim 1. in, The upstream end of the shield (21) is spaced apart from the upstream section wall (13) in the axial direction.

3. The combustion section (01) according to claim 1 or 2. in, The inner segment wall (14) includes a recess (22) that is spaced apart from the upstream segment wall (13) and from the downstream end of the inner segment wall (14) and is covered by the shield (21).

4. The combustion section (01) according to claim 1 or 2. in, The free distance (24) from the shield (21) to the radially inner side of the inner segment wall (14) is at least 0.1 times and at most 0.3 times the thickness (23) from the radially outer side of the inner segment wall (14) to the radially inner side of the shield (21).

5. The combustion section (01) according to claim 1 or 2. in, The free distance (24) from the shield (21) to the radially inner side of the inner section wall (14) is at least 0.5 times and at most 1.5 times the distance from the shield (21) to the outer diffuser wall (16).

6. The combustion section (01) according to claim 1 or 2. in, An inner cover (25) is attached to the outside of the inner segment wall (14), and there is an inner gap (26) between the outside of the inner segment wall (14) and the inner cover (25).

7. The combustion section (01) according to claim 6. in, The inner cover (25) includes a bend (27) at its downstream end.

8. The combustion section (01) according to claim 6. in, The width of the inner gap (26) is at least 0.6 times and at most 1.5 times the free distance (24) from the shield (21) to the radially inner side of the inner section wall (14).

9. The combustion section (01) according to claim 6. in, An upstream cover (28) is attached to the downstream side of the upstream section wall (13), and an upstream gap (29) is formed between the downstream side of the upstream section wall (13) and the upstream cover (28).

10. The combustion section (01) according to claim 9. in, The upstream cover (28) includes a bend (30) at its radially outer end.

11. The combustion section (01) according to claim 9. in, The width of the upstream gap (29) is at least 0.6 times and at most 1.5 times the free distance (24) from the shield (21) to the radially inner side of the inner section wall (14).

12. The combustion section (01) according to claim 9. in, The inner cover (25) is connected to the upstream cover (28) such that there is a continuous gap from the inner cover (25) and the upstream cover (28) to the inner section wall (14) and the upstream section wall (13).

13. The combustion section (01) according to claim 3. in, The inner section wall (14) forms a continuous surface on the radially inner side of the shield (21) located upstream and downstream of the shield (21).

14. The combustion section (01) according to claim 1 or 2. in, The free distance (24) from the shield (21) to the radially inner side of the inner segment wall (14) is at least 0.15 times and / or at most 0.2 times the thickness (23) from the radially outer side of the inner segment wall (14) to the radially inner side of the shield (21).

15. The combustion section (01) according to claim 1 or 2. in, The free distance (24) from the shield (21) to the radially inner side of the inner section wall (14) is at least 0.7 times and / or at most 0.9 times the distance from the shield (21) to the outer diffuser wall (16).

16. The combustion section (01) according to claim 7. in, The bent portion (27) is in contact with the inner section wall (14).

17. The combustion section (01) according to claim 6. in, The width of the inner gap (26) is at least 0.8 times and / or at most 1.2 times the free distance (24) from the shield (21) to the radially inner side of the inner section wall (14).

18. The combustion section (01) according to claim 10. in, The bent portion (30) is in contact with the upstream section wall (13).

19. The combustion section (01) according to claim 9. in, The width of the upstream gap (29) is at least 0.8 times and / or at most 1.2 times the free distance (24) from the shield (21) to the radially inner side of the inner section wall (14).

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