Supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance

Abstract

The supercritical carbon dioxide turbine structure capable of adjusting the blade top clearance comprises a main shaft, the main shaft is sleeved with a turbine impeller, a nozzle seat and a casing, the casing is arranged on the blade side of the turbine impeller, and the nozzle seat is arranged on the blade back side of the turbine impeller; dynamic and static gaps are formed between the blade side of the turbine impeller and the casing as well as between the turbine impeller and the nozzle seat; the nozzle holder and the cartridge receiver are connected in a clinging manner; a gasket groove used for installing a gasket is formed in the end face of the side, away from the turbine impeller, of the case and faces the end face of the end of the nozzle seat, and the gasket groove is arranged in the circumferential direction. The blade height at the rim of the turbine impeller is greater than the original design value; the problem that the blade top end of the turbine impeller and the casing are prone to collision and abrasion in the actual operation process is solved, and meanwhile the problem that the blade top clearance loss is too large is solved.

Description

Technical Field

[0001] The invention belongs to the field of turbine machinery, and in particular relates to a supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance. Background Art

[0002] The supercritical carbon dioxide Brayton cycle is currently the most popular new power cycle. It has the characteristics of strong compactness, high cycle efficiency, and the ability to match a variety of heat sources. Supercritical carbon dioxide has a high centripetal turbine expansion ratio and excellent aerodynamic performance, and is often used as a heat-to-work conversion component in hundreds of kW cycles.

[0003] In the actual mechanical structure, there is a dynamic and static gap between the turbine blades and the casing. Too large a gap will cause serious tip leakage loss, affecting the aerodynamic performance of the turbine, and further leading to a reduction in cycle efficiency and output power. However, too small a gap will cause the impeller and the casing to have the risk of rubbing during operation. Therefore, it is very important to adjust the tip clearance and ensure performance during turbine operation. Tip residual height is currently an effective means to reduce tip leakage loss. By increasing the impeller blade inlet height, the working fluid flowing out of the nozzle is prevented from directly flowing into the impeller tip clearance, reducing the tip clearance flow, and thus reducing losses. In addition, by adding or removing gaskets to adjust the tip clearance size, the risk of dynamic and static clearance rubbing can be avoided. However, adding gaskets will inevitably lead to a gap that does not exist at the top of the nozzle blade, causing additional leakage loss. Therefore, by reserving the nozzle blade height margin, the flow channel can be guaranteed to be continuous. While adjusting the tip clearance, the turbine can also maintain relatively good aerodynamic performance. Summary of the invention

[0004] The object of the present invention is to provide a supercritical carbon dioxide turbine structure capable of adjusting the blade tip clearance, thereby solving the above-mentioned shortcomings of the dynamic and static clearance between the existing turbine impeller and the casing.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance, comprising a main shaft, on which a turbine impeller, a nozzle seat and a casing are mounted, wherein the casing is arranged on the blade side of the turbine impeller, and the nozzle seat is arranged on the back side of the blade of the turbine impeller; dynamic and static clearances are arranged between the blade side of the turbine impeller and the casing, and between the turbine impeller and the nozzle seat; the nozzle seat and the casing are tightly connected; The casing is provided with a gasket groove for installing a gasket on an end surface of the casing which is away from the turbine impeller and faces one end of the nozzle seat, and the gasket groove is arranged in a circumferential direction; The blade height at the wheel rim of the turbine impeller is greater than its original design value.

[0006] Preferably, a plurality of nozzle blades are arranged on the nozzle seat, and the height of each nozzle blade is greater than its original design value; a plurality of nozzle grooves are opened on the casing, and the nozzle grooves are matched with the nozzle blades.

[0007] Preferably, the difference between the height of the nozzle blade and the original design value is the maximum adjustable height of the spacer.

[0008] Preferably, the difference between the blade height at the wheel rim of the turbine impeller and the original design value is the maximum adjustable height of the gasket.

[0009] Preferably, the gasket is a group of multiple gaskets with different thicknesses.

[0010] Preferably, a first volute sub-flow channel is provided on the casing, a second volute sub-flow channel is provided on the nozzle seat, the first volute sub-flow channel and the second volute sub-flow channel are butt-connected to form a volute flow channel, and the volute flow channel is arranged close to one side of the turbine impeller.

[0011] Preferably, a sealing groove is provided on the end surface of the casing facing the nozzle seat, and the sealing grooves are arranged circumferentially; an O-ring is installed in the sealing groove.

[0012] Preferably, the sealing groove is disposed between the gasket groove and the volute flow passage.

[0013] Preferably, the nozzle seat is connected to the main shaft via a bearing.

[0014] Preferably, the maximum adjustable height of the spacer is 10 times the blade tip clearance value. Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a supercritical carbon dioxide turbine structure capable of adjusting the blade tip clearance, which increases the blade tip clearance of the turbine impeller by arranging a gasket between the casing and the nozzle seat, thereby solving the problem of easy friction between the blade tip of the turbine impeller and the casing during actual operation; at the same time, there is also the problem of blade tip clearance loss in the supercritical carbon dioxide centrifugal turbine, so the present invention solves the problem of excessive blade tip clearance loss by increasing the impeller inlet blade height to avoid the working fluid from directly flowing into the clearance.

[0015] Furthermore, in the process of adding gaskets, the distance between the casing and the nozzle seat will increase. By increasing the height margin of the nozzle blades, it is ensured that no additional gap will appear at the top of the nozzle blades during the adjustment process, thereby preventing additional losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention; Among them: 1-turbine impeller, 2-main shaft, 3-nozzle seat, 4-casing, 5-O-ring seal, 6-gasket set, 7-bearing, 8-locking nut. DETAILED DESCRIPTION

[0017] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0018] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0019] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0020] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0021] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0022] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0023] Example 1 The present embodiment provides a supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance, comprising a main shaft 2, wherein the main shaft 2 is provided with a turbine impeller 1, a nozzle seat 3 and a casing 4, wherein: The casing 4 is disposed on the blade side of the turbine impeller, and the nozzle seat 3 is disposed on the blade back side of the turbine impeller 1 .

[0024] Dynamic and static gaps are provided between the blade side of the turbine impeller 1 and the casing 4, and between the turbine impeller 1 and the nozzle seat 3; the nozzle seat 3 and the casing 4 are tightly connected.

[0025] The casing 4 is provided with a gasket groove 6 for installing a gasket on an end surface thereof which is away from the turbine impeller 1 and faces the nozzle seat 3. The gasket groove 6 is arranged in a circumferential direction.

[0026] The blade height at the wheel rim of the turbine impeller 1 is greater than its original design value, so that the top of the blade is higher than the end surface of the casing facing the nozzle seat 3.

[0027] In this embodiment, the blade tip clearance between the turbine impeller 1 and the casing 4 is constant in the normal direction in the initial installation state. In the actual operation process, the thickness of the gasket is adjusted according to the thermal expansion deformation and dynamic and static friction of the rotor, and the maximum adjustable height of the gasket is 10 times the blade tip clearance value; the blade tip clearance between the flat impeller and the casing is adjusted by adding or removing gaskets, and the minimum blade tip clearance is obtained when there is no gasket, and its size is the initial design value.

[0028] By arranging a gasket between the casing and the nozzle seat to increase the blade tip clearance of the turbine impeller, the problem of easy friction between the blade tip of the turbine impeller 1 and the casing 4 during actual operation is solved; at the same time, there is also the problem of blade tip clearance loss in the supercritical carbon dioxide centrifugal turbine, so this embodiment solves the problem of excessive blade tip clearance loss by increasing the impeller inlet blade height to avoid the working fluid from directly flowing into the gap.

[0029] Example 2 Based on Example 1, this example provides a supercritical carbon dioxide turbine structure capable of adjusting the blade tip clearance, characterized in that the difference between the blade height at the rim of the turbine impeller and the original design value is the maximum adjustable height of the gasket.

[0030] Example 3 Based on Example 1, this embodiment provides a supercritical carbon dioxide turbine structure capable of adjusting the blade tip clearance, characterized in that a plurality of nozzle blades are arranged on the nozzle seat 3, and the height of each nozzle blade is greater than its original design value; a plurality of nozzle grooves 9 are opened on the casing 4, and the shape of the nozzle grooves 9 matches the nozzle blades.

[0031] The depth of the nozzle groove 9 is consistent with the difference between the height of the nozzle blade and the original design value.

[0032] In this embodiment, in the process of adding gaskets, the distance between the casing 4 and the nozzle seat 3 will increase. By increasing the nozzle blade height margin, it is ensured that no additional gap will appear at the top of the nozzle blade during the adjustment process, thereby preventing additional losses.

[0033] Example 4 On the basis of Example 1, this example provides a supercritical carbon dioxide turbine structure capable of adjusting the tip clearance, wherein the difference between the height of the nozzle blade and the original design value is the maximum adjustable height of the gasket.

[0034] Example 5 On the basis of Example 1, this example provides a supercritical carbon dioxide turbine structure capable of adjusting the blade tip clearance, wherein the gasket is a group of multiple gaskets of different thicknesses, which are used to adjust the size of the blade tip clearance according to actual operating conditions.

[0035] Example 6 On the basis of Example 1, this embodiment provides a supercritical carbon dioxide turbine structure capable of adjusting the blade tip clearance, wherein a first volute sub-flow channel is provided on the casing 4, and a second volute sub-flow channel is provided on the nozzle seat 3, the first volute sub-flow channel and the second volute sub-flow channel are butt-connected to form a volute flow channel, and the volute flow channel is arranged close to one side of the turbine impeller.

[0036] The dividing plane between the first and second volute sub-flow passages is based on the blade tip plane of the nozzle blade basic design height.

[0037] A sealing groove 5 is provided on the end surface of the casing 4 facing the nozzle seat, and the sealing groove is arranged circumferentially; an O-ring is installed in the sealing groove to prevent the supercritical carbon dioxide working medium in the main channel from leaking outward.

[0038] Example 7 On the basis of Example 1, this example provides a supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance, wherein a bearing 7 is provided between the nozzle seat 3 and the main shaft 2.

[0039] Example 8 On the basis of Example 1, this example provides a supercritical carbon dioxide turbine structure capable of adjusting the blade tip clearance, wherein a locking nut 8 is further provided on the main shaft, and the locking nut is located in front of the turbine impeller for axial positioning of the turbine impeller.

[0040] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance, characterized in that: The invention comprises a main shaft, on which a turbine impeller, a nozzle seat and a casing are mounted, wherein the casing is arranged on the blade side of the turbine impeller, and the nozzle seat is arranged on the back side of the blade of the turbine impeller; a dynamic and static gap is arranged between the blade side of the turbine impeller and the casing, and between the turbine impeller and the nozzle seat; and the nozzle seat and the casing are closely connected; The casing is provided with a gasket groove for installing a gasket on an end surface of the casing which is away from the turbine impeller and faces one end of the nozzle seat, and the gasket groove is arranged in a circumferential direction; The blade height at the wheel rim of the turbine impeller is greater than its original design value.

2. A supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 1, characterized in that: The nozzle seat is provided with a plurality of nozzle blades, and the height of each nozzle blade is greater than its original design value; the casing is provided with a plurality of nozzle grooves, and the nozzle grooves are matched with the nozzle blades.

3. The supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 2, characterized in that: The difference between the height of the nozzle blade and the original design value is the maximum adjustable height of the gasket.

4. The supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 1, characterized in that: The difference between the blade height at the wheel rim of the turbine impeller and the original design value is the maximum adjustable height of the gasket.

5. The supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 1, characterized in that: The gasket is a group of multiple gaskets with different thicknesses.

6. The supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 1, characterized in that: The casing is provided with a first volute sub-flow channel, the nozzle seat is provided with a second volute sub-flow channel, the first volute sub-flow channel and the second volute sub-flow channel are butt-connected to form a volute flow channel, and the volute flow channel is arranged close to one side of the turbine impeller.

7. A supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 6, characterized in that: A sealing groove is provided on the end surface of the casing facing the nozzle seat, and the sealing groove is arranged circumferentially; an O-type sealing ring is installed in the sealing groove.

8. The supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 7, characterized in that: The sealing groove is disposed between the gasket groove and the volute flow passage.

9. The supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 1, characterized in that: The nozzle seat is connected to the main shaft through a bearing.

10. The supercritical carbon dioxide turbine structure capable of adjusting blade tip clearance according to claim 1, characterized in that: The maximum adjustable height of the spacer is 10 times the blade tip clearance value.

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