An axial force adjustment structure for a closed-loop impeller centrifugal compressor and a centrifugal compressor

Abstract

This application provides an axial force adjustment structure for a closed-loop impeller centrifugal compressor and the compressor itself. The axial force adjustment structure includes an impeller back, an adjustment structure stator, and an adjustment structure rotor. A leakage flow pressure-bearing surface is formed between the adjustment structure stator and the impeller back. The adjustment structure rotor includes a maximum outer radius in the radial direction. By adjusting the size of the maximum outer radius, the area of ​​the leakage flow pressure-bearing surface is adjusted. Compared to conventional closed-loop impeller centrifugal compressors, adjusting the maximum outer radius of the adjustment structure rotor adjusts the pressure-bearing area of ​​the high-pressure leakage flow borne by the closed impeller back, thereby effectively adjusting the axial force borne by the compressor rotor and ensuring the stability and reliability of the bearings under all operating conditions.

Description

Technical Field

[0001] This invention relates to the field of centrifugal compressor technology, specifically to an axial force adjustment structure for a closed impeller centrifugal compressor and a centrifugal compressor. Background Technology

[0002] Centrifugal compressors have advantages such as high compression efficiency, small size, and light weight, and are widely used in energy and fluid transportation devices, such as engine turbochargers, micro gas turbines, closed-cycle turbine power, and compressed air energy storage.

[0003] Centrifugal compressor impellers can be classified into open impellers, semi-open impellers, and closed impellers. For compressors using high-pressure, high-density working fluids, such as supercritical carbon dioxide power cycle compressors, closed impellers are generally used. This reduces flow losses caused by leakage at the blade tip clearance, improves the efficiency of the centrifugal compressor, and expands the stable operating range of the centrifugal compressor.

[0004] During the operation of a centrifugal compressor, the impeller back pressure is greater than the impeller cover pressure, thus generating axial force. The magnitude of this axial force varies under different operating conditions. When the axial force exceeds the bearing's load-bearing capacity, it leads to a decrease in bearing life. Currently, axial force is generally estimated through simulation during the design process, and the structural design is used to balance the axial force as much as possible, keeping it within the bearing's allowable range. However, during actual compressor operation, the axial force may deviate from the design value due to various factors, especially in high-pressure supercritical carbon dioxide closed-circuit compressors. Small changes in operating conditions and structural dimensions can lead to significant variations in axial force, making accurate estimation during the design phase difficult and easily resulting in bearing failure due to excessive axial force.

[0005] To ensure the reliable operation of the centrifugal compressor bearings, an axial force adjustment structure needs to be incorporated into the compressor's structural design. The axial force is adjusted based on the actual operating test results of the compressor to ensure that the compressor's axial force remains within the allowable range of the bearings under all operating conditions.

[0006] Therefore, researchers in this field urgently need to develop a structurally sound axial force adjustment structure for closed-loop impeller centrifugal compressors. Summary of the Invention

[0007] In view of this, in order to balance the axial force of the closed impeller centrifugal compressor and more effectively ensure the stability and reliability of the bearing operation of the closed impeller centrifugal compressor under all operating conditions, this embodiment of the invention provides an axial force adjustment structure for a closed impeller centrifugal compressor.

[0008] To achieve the above objectives, one embodiment of the present invention provides an axial force adjustment structure for a closed impeller centrifugal compressor. The axial force adjustment structure includes an impeller back, an adjustment structure stator fixedly connected to the compressor housing, and an adjustment structure rotor fixedly connected to the compressor main shaft and disposed between the adjustment structure stator and the compressor main shaft.

[0009] A leakage flow pressure bearing surface is formed between the adjusting structure stator and the impeller back;

[0010] The adjusting structure rotor includes a maximum outer radius in the radial direction. By adjusting the size of the maximum outer radius, the area of ​​the leakage flow pressure bearing surface can be adjusted.

[0011] According to some embodiments of the closed impeller centrifugal compressor axial force adjustment structure of this application, a sealing grate is provided between the rotor component and the stator component of the adjustment structure.

[0012] According to some embodiments of the closed impeller centrifugal compressor axial force adjustment structure of this application, the sealing grates are disposed on the stator of the adjustment structure.

[0013] According to some embodiments of the closed impeller centrifugal compressor axial force adjustment structure of this application, the radial cross section of the rotor component of the adjustment structure is a "Z" shaped structure.

[0014] According to some embodiments of the closed impeller centrifugal compressor axial force adjustment structure of this application, the "Z"-shaped structure includes a maximum outer circular surface structure and a minimum outer circular surface structure, wherein the minimum outer circular surface structure is fixedly connected to the compressor main shaft.

[0015] According to some embodiments of the closed impeller centrifugal compressor axial force adjustment structure of this application, the maximum outer circular surface structure forms a first annular cavity between the compressor main shaft and the structure.

[0016] According to some embodiments of the closed impeller centrifugal compressor axial force adjustment structure of this application, the stator component of the adjustment structure includes a left stator part and a right stator part, and a second annular cavity is formed between the left stator part, the right stator part and the maximum outer circular surface structure.

[0017] According to some embodiments of the closed impeller centrifugal compressor axial force adjustment structure of this application, the sealing grate includes a first sealing grate and a second sealing grate, the first sealing grate is disposed on the left stator portion, and the second sealing grate is disposed on the right stator portion.

[0018] According to some embodiments of the axial force adjustment structure of the closed impeller centrifugal compressor of this application, the algorithm formula for adjusting the area of ​​the leakage flow pressure bearing surface by adjusting the size of the maximum outer radius is as follows:

[0019]

[0020] Where S is the area of ​​the leakage flow bearing surface formed between the stator component of the regulating structure and the impeller back; r2 is the maximum outer radius of the rotor component of the regulating structure; and r3 is the maximum radius of the impeller back.

[0021] Another embodiment of the present invention provides a centrifugal compressor, including a compressor housing, a compressor main shaft located within the compressor housing, a hub fixedly connected to one end of the compressor main shaft, a wheel cover coaxially disposed with the wheel hub and sleeved on the outside of the wheel hub, a plurality of impeller blades distributed circumferentially along the wheel hub and connected between the wheel hub and the wheel cover, and further including the axial force adjustment structure of the closed impeller centrifugal compressor described in any of the above embodiments.

[0022] The beneficial effects of this invention are:

[0023] This invention adjusts the pressure-bearing area of ​​the high-pressure leakage flow on the back of the closed impeller by adjusting the maximum outer radius of the rotor component of the adjustment structure, thereby adjusting the axial force borne by the compressor rotor.

[0024] Specifically, the axial force adjustment structure of the closed-loop impeller centrifugal compressor of the present invention includes an impeller back, an adjustment structure stator fixedly connected to the compressor housing, and an adjustment structure rotor fixedly connected to the compressor main shaft and disposed between the adjustment structure stator and the compressor main shaft; a leakage flow pressure-bearing surface is formed between the adjustment structure stator and the impeller back; the adjustment structure rotor includes a maximum outer radius in the radial direction, and the area of ​​the leakage flow pressure-bearing surface is adjusted by adjusting the size of the maximum outer radius. Compared with conventional closed-loop impeller centrifugal compressors, the pressure-bearing area of ​​the high-pressure leakage flow borne by the closed impeller back can be adjusted by adjusting the size of the maximum outer radius of the adjustment structure rotor based on the actual operation test results of the compressor, thereby effectively adjusting the axial force borne by the compressor rotor and ensuring the stability and reliability of the bearing operation of the closed-loop impeller centrifugal compressor under all operating conditions. Attached Figure Description

[0025] The following figures are provided to further illustrate this application and form part of this application. They are intended to be illustrative and explanatory only, and are not intended to limit the scope of the invention. In the figures:

[0026] Figure 1 This is a schematic diagram of the installation method of the axial force adjustment structure of the closed impeller centrifugal compressor according to an embodiment of this application;

[0027] Figure 2This is a schematic diagram of the main flow and leakage flow directions in a closed-loop impeller centrifugal compressor according to an embodiment of this application;

[0028] Figure 3 This is a right-side structural schematic diagram of the impeller back and adjusting structure rotor component, and the compressor main shaft of some embodiments of this application;

[0029] Figure 4 This is a three-dimensional cross-sectional view of the adjustment structure rotor component of some embodiments of this application.

[0030] Figure label:

[0031] 1. Impeller blade; 10. Impeller back; 11. Leakage flow pressure bearing surface; 100. Compressor main shaft; 101. Hub; 102. Bearing;

[0032] 21. Adjustment structure stator component; 22. Adjustment structure rotor component; 211. Left stator section; 212. Right stator section; 213. First sealing grate; 214. Second sealing grate; 221. Maximum outer circular surface structure; 222. Minimum outer circular surface structure;

[0033] 30. Sealing grates on the impeller shroud side; 31. First annular cavity; 32. Second annular cavity. Detailed Implementation

[0034] The following illustrations will disclose several embodiments of this application, providing a clear and complete description of the technical solution of the present invention. The accompanying drawings, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0036] The technical solutions of the various embodiments of this application can be combined with each other, but only if they are based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0037] The following are examples of specific implementation processes provided to illustrate the technical solutions to be protected in this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can implement this application by different technical means under the guidance of the concept of this application. Therefore, this application is not limited to the specific embodiments below.

[0038] Figure 1 A schematic diagram of an axial force adjustment structure for a closed-loop centrifugal compressor according to an embodiment of the present invention is shown. The closed-loop centrifugal compressor of this embodiment includes a compressor housing 3, a compressor main shaft 100 located within the compressor housing 3, a hub 101 fixedly connected to one end of the compressor main shaft 100, a wheel cover 12 coaxially arranged with the hub 101 and sleeved on the outside of the hub 101, a plurality of impeller blades 1 spaced circumferentially along the hub 101 and connected between the hub 101 and the wheel cover 12, and an axial force adjustment structure. The impeller blades 1, hub 101, and wheel cover 12 together constitute the closed impeller of the centrifugal compressor. The axial force adjustment structure is located on the right side of the closed impeller, i.e., away from the inlet direction of the centrifugal compressor. Its adjustment structure rotor 22 is coaxially arranged with the hub and fixedly sleeved on the compressor main shaft 100.

[0039] In this embodiment, the flow of the working fluid in the centrifugal compressor is as follows: Figure 2 As shown, the working fluid enters the closed impeller flow channel axially through the centrifugal compressor inlet. The high-speed rotating closed impeller performs work on the working fluid, which becomes a high-pressure working fluid at the impeller outlet. The high-pressure working fluid at the impeller outlet is divided into a mainstream section and a leakage flow section. The high-pressure airflow of the mainstream section enters subsequent components such as the diffuser, volute, and return flow device. Part of the leakage flow enters the leakage channel on the impeller shroud side, and the other part enters the leakage channel on the impeller back side.

[0040] The technical solution of this application mainly controls the influence of the high-pressure working fluid airflow entering the leakage channel on the back side of the impeller on the axial force of the closed impeller centrifugal compressor. The axial force adjustment structure of the closed impeller centrifugal compressor with specific structure and function is designed to effectively adjust the axial force borne by the compressor rotor and ensure the stability and reliability of the bearing operation of the closed impeller centrifugal compressor under all operating conditions.

[0041] The following is in conjunction with the appendix Figure 1-4This application describes an embodiment of an axial force adjustment structure for a closed-loop impeller centrifugal compressor.

[0042] Please see Figure 1 An axial force adjustment structure for a closed impeller centrifugal compressor is disclosed in this application embodiment. The axial force adjustment structure includes an impeller back 10, an adjustment structure stator 21 fixedly connected to the compressor housing, and an adjustment structure rotor 22 fixedly connected to the compressor main shaft 100 and disposed between the adjustment structure stator 21 and the compressor main shaft 100. A leakage flow pressure bearing surface 11 is formed between the adjustment structure stator 21 and the impeller back 10.

[0043] It is understood that the impeller back side leakage channel is formed between the adjusting structure stator 21 and the impeller back 10, and the leakage flow pressure bearing surface 11 is the projection of the impeller back side leakage channel onto the impeller back surface.

[0044] Combination Figure 2 , Figure 3 As shown, the adjusting structure rotor 22 includes a maximum outer radius r2 in the radial direction. By adjusting the size of the maximum outer radius r2, the area of ​​the leakage flow pressure bearing surface can be adjusted.

[0045] Specifically, the important parameters related to the axial force adjustment structure and the flow path of the high-pressure working fluid are as follows: Figure 2 As shown, the right view of the closed impeller back and axial force adjustment structure rotor component is as follows. Figure 3 As shown. r1 is the radius of the compressor rotor shaft at the mounting location of the axial force adjustment structure, r2 is the maximum outer radius of the rotor component of the adjustment structure, and r3 is the maximum radius of the impeller back. Since the three key structural parameters satisfy r1 < r2 < r3, therefore according to Figure 3 Based on the geometric relationship, the algorithm formula for calculating the area S1 of the pressure-bearing surface on the back of the closed impeller, i.e., the area of ​​the leakage flow pressure-bearing surface, is as follows:

[0046]

[0047] Understandably, based on the varying axial forces generated by the closed-circuit centrifugal compressor under different operating conditions, the key parameter r2 is adjusted to regulate the area of ​​the high-pressure bearing surface, i.e., the area S1 of the leakage flow bearing surface, thereby regulating the axial force on the compressor rotor. When the leftward axial force is larger, r2 is increased to decrease S1, thus reducing the leftward axial force; conversely, when the rightward axial force is larger, r2 is decreased to increase S1, thus increasing the leftward axial force. By adjusting r2, the maximum axial force of the compressor under different operating conditions is controlled to not exceed the allowable range of the bearing, effectively ensuring the stability and reliability of the bearing operation of the closed-circuit centrifugal compressor under all operating conditions.

[0048] It should be noted that the specific means of adjusting the maximum outer radius r2 of the adjusting structure rotor 22 in this embodiment of the application can be based on the actual operation test results of the compressor, by replacing the adjusting structure rotor with a suitable maximum outer radius; or, based on the actual operation test results of the compressor, the maximum outer radius of the adjusting structure rotor 22 can be automatically adjusted in real time. Specifically, the axial force adjustment structure of the closed impeller centrifugal compressor further includes: setting a pressure sensor and a controller at the impeller back, and setting a retractable outer surface structure 221 of the maximum outer surface of the adjusting structure rotor 22. The pressure sensor collects and monitors the axial pressure data of the leakage flow pressure-bearing surface in real time. Based on the real-time monitored axial pressure data, the controller controls the retraction and expansion of the maximum outer surface structure, thereby achieving real-time adjustment of the maximum outer radius to adjust the area of ​​the high-pressure pressure-bearing surface, and thus enabling real-time adjustment and control of the magnitude of the axial force.

[0049] As a preferred embodiment of the axial force adjustment structure for a closed-loop impeller centrifugal compressor, such as Figure 1 , Figure 2 As shown, the radial cross-section of the adjusting structure rotor 22 is a "Z" shaped structure. The "Z" shaped structure includes a maximum outer circular surface structure 221 and a minimum outer circular surface structure 222. The minimum outer circular surface structure 222 is fixedly connected to the compressor main shaft 100.

[0050] Furthermore, the maximum outer circular surface structure 221, the compressor main shaft and the hub 101 fixedly connected to one end, and the vertical platform of the Z-shaped structure enclose and form a first annular cavity 31. The adjusting structure stator 21 includes a left stator part 211 and a right stator part 212, and a second annular cavity 32 is formed between the left stator part 211, the right stator part 212 and the maximum outer circular surface structure 221.

[0051] It should be noted that the first annular cavity 31 and the second annular cavity 32 in this embodiment are designed to provide a buffer space for the leakage flow, while also facilitating the lightweighting of the compressor. The right stator 212 is fixedly connected to the compressor housing and also serves as an internal support structure for the compressor, while providing the necessary conditions for forming the second annular cavity 32 and assembling the second sealing grate 214.

[0052] Furthermore, a sealing grate is provided between the adjusting structure rotor 22 and the adjusting structure stator 21, and the sealing grate is provided on the arc surface of the adjusting structure stator near the adjusting structure rotor 22.

[0053] Furthermore, the sealing teeth include a first sealing tooth 213 and a second sealing tooth 214, with the first sealing tooth 213 disposed on the left stator portion 211 and the second sealing tooth 214 disposed on the right stator portion 212.

[0054] Specifically, the leakage flow entering the leakage channel on the back side of the impeller first undergoes a first pressure reduction through the first sealing grate 213, making the pressure acting on the vertical platform 223 of the Z-shaped adjustment structure rotor component smaller, thereby reducing the axial force acting here. Then, it undergoes a second pressure reduction through the second sealing grate 214, further reducing the overall leakage flow.

[0055] like Figure 4 The schematic diagram of the three-dimensional cross-sectional structure of the rotor component of the adjustment structure shown has a cross-sectional shape similar to a Z-shape, forming two outer circular surfaces with different radii, namely the maximum outer circular surface structure 221 and the minimum outer circular surface structure 222. The position of the minimum outer circular surface structure 222 is basically fixed, while the position of the maximum outer circular surface structure 221 changes with the adjustment of the aforementioned key parameter r2. While adjusting the maximum outer circular surface structure 221, the radius of the adjusting structure stator 21 of the axial force adjustment structure and its sealing teeth at this location are adjusted accordingly to ensure that the sealing gap at this location remains unchanged, thereby maintaining the pressure drop of the leakage flow at this location.

[0056] In summary, the axial force adjustment structure of the closed-loop impeller centrifugal compressor of the present invention includes an impeller back 10, an adjustment structure stator 21 fixedly connected to the compressor housing, and an adjustment structure rotor 22 fixedly connected to the compressor main shaft 100 and disposed between the adjustment structure stator 21 and the compressor main shaft 100. A leakage flow pressure-bearing surface 11 is formed between the adjustment structure stator 21 and the impeller back 10. The adjustment structure rotor 22 includes a maximum outer radius r1 in the radial direction. By adjusting the size of the maximum outer radius, the area of ​​the leakage flow pressure-bearing surface can be adjusted. Compared with conventional closed-loop impeller centrifugal compressors, the pressure-bearing area of ​​the high-pressure leakage flow borne by the closed impeller back can be adjusted by adjusting the size of the maximum outer radius of the adjustment structure rotor based on the actual operating test results of the compressor. This effectively adjusts the axial force borne by the compressor rotor, ensuring the stability and reliability of the bearing operation of the closed-loop impeller centrifugal compressor under all operating conditions.

[0057] It should be noted that, in the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0058] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

[0059] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0060] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. An axial force adjustment structure for a closed-loop impeller centrifugal compressor, characterized in that, include: Impeller back; An adjusting structure stator is provided, which forms a leakage flow pressure bearing surface with respect to the impeller back; An adjusting structure rotor is fixedly connected to the compressor main shaft and disposed between the adjusting structure stator and the compressor main shaft; the adjusting structure rotor includes a maximum outer radius in the radial direction, and the area of ​​the leakage flow pressure bearing surface is adjusted by adjusting the size of the maximum outer radius.

2. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 1, characterized in that, A sealing grate is provided between the rotor component of the adjustment structure and the stator component of the adjustment structure.

3. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 2, characterized in that, The sealing grates are mounted on the stationary component of the adjustment structure.

4. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 2, characterized in that, The radial cross-section of the rotor component of the adjustment structure is a "Z" shaped structure.

5. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 4, characterized in that, The "Z"-shaped structure includes a maximum outer circular surface structure and a minimum outer circular surface structure, with the minimum outer circular surface structure fixedly connected to the compressor main shaft.

6. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 5, characterized in that, The largest outer circular surface structure forms a first annular cavity with the compressor main shaft.

7. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 5, characterized in that, The adjusting structure stator includes a left stator part and a right stator part, and a second annular cavity is formed between the left stator part, the right stator part and the maximum outer circular surface structure.

8. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 7, characterized in that, The sealing grate includes a first sealing grate and a second sealing grate. The first sealing grate is disposed on the left stator portion, and the second sealing grate is disposed on the right stator portion.

9. The axial force adjustment structure for a closed-loop impeller centrifugal compressor as described in claim 1, characterized in that, The algorithm formula for adjusting the area of ​​the leakage flow pressure-bearing surface by adjusting the size of the maximum outer radius is as follows: Where S is the area of ​​the leakage flow bearing surface formed between the stator component of the regulating structure and the impeller back; r2 is the maximum outer radius of the rotor component of the regulating structure; and r3 is the maximum radius of the impeller back.

10. A centrifugal compressor, comprising a compressor housing, a compressor main shaft located within the compressor housing, a hub fixedly connected to one end of the compressor main shaft, a wheel cover coaxially disposed with the wheel hub and sleeved on the outside of the wheel hub, and a plurality of impeller blades spaced circumferentially along the wheel hub and connected between the wheel hub and the wheel cover, characterized in that, It also includes the axial force adjustment structure for the closed impeller centrifugal compressor as described in any one of claims 1-9.

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