Axial force adjusting structure of closed impeller centrifugal compressor and centrifugal compressor

Abstract

The invention provides an axial force adjusting structure of a closed impeller centrifugal compressor and the centrifugal compressor. The axial force adjusting structure of the closed impeller centrifugal compressor comprises an impeller back, an adjusting structure stator part and an adjusting structure rotor part. A leakage flow pressure-bearing surface is formed between the adjusting structure stator piece and the impeller back; the adjusting structure rotor part comprises the maximum outer circle radius in the radial direction, and the area of the leakage flow pressure-bearing face is adjusted by adjusting the maximum outer circle radius. Compared with a conventional closed impeller centrifugal compressor, the closed impeller centrifugal compressor has the advantages that the pressure bearing area of high-pressure leakage flow borne by the wheel back of the closed impeller is adjusted by adjusting the size of the maximum outer circle radius of the rotor part of the adjusting structure, so that the axial force borne by the rotor of the compressor is effectively adjusted, and the service life of the compressor is prolonged. And the technical effect that the working stability and reliability of the bearing of the closed impeller centrifugal compressor under all working conditions are ensured is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal compressors, and in particular to an axial force regulating structure of a closed impeller centrifugal compressor and a centrifugal compressor. Background Art

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

[0003] The impellers of centrifugal compressors can be divided into open impellers, semi-open impellers and closed impellers. For compressors with high pressure and high density working fluids such as supercritical carbon dioxide power cycle compressors, closed impellers are generally used to reduce flow losses caused by tip clearance leakage, improve the efficiency of centrifugal compressors, and expand the stable working range of centrifugal compressors.

[0004] During the operation of the centrifugal compressor, the impeller back pressure is greater than the wheel cover pressure, which generates an axial force. Under different operating conditions, the axial force generated by the impeller is of different magnitudes. When the axial force is too large and exceeds the bearing capacity, it will lead to a decrease in the bearing life. At present, the axial force is generally estimated through simulation during the design process, and the axial force is balanced as much as possible through structural design to keep it within the allowable range of the bearing. However, during the actual operation of the compressor, the axial force may deviate from the design value due to various factors, especially when applied to supercritical carbon dioxide closed compressors with higher working pressures. Small changes in operating conditions and structural dimensions will lead to large changes in axial force, which is difficult to accurately estimate during the design process, and it is easy to cause the axial force to exceed the limit and cause bearing failure.

[0005] In order to ensure the reliable operation of the centrifugal compressor bearings, it is necessary to set an axial force adjustment structure when designing the compressor structure, and adjust the axial force according to the actual operation test results of the compressor to ensure that the axial force of the compressor is within the allowable range of the bearing under all operating conditions of the compressor.

[0006] Therefore, it is urgent for researchers in this field to develop a rationally structured axial force regulating structure for a closed impeller centrifugal compressor. 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, an embodiment of the present invention provides an axial force adjustment structure for a closed impeller centrifugal compressor.

[0008] To achieve the above-mentioned purpose, an embodiment of the present invention provides an axial force adjustment structure of a closed impeller centrifugal compressor, the axial force adjustment structure comprising an impeller wheel back, an adjustment structure stator component fixedly connected to a compressor housing, and an adjustment structure rotor component fixedly connected to a compressor main shaft and arranged between the adjustment structure stator component and the compressor main shaft;

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

[0010] The regulating structure rotor member comprises a maximum outer circle radius along the radial direction, and the area of ​​the leakage flow pressure bearing surface is regulated by adjusting the size of the maximum outer circle radius.

[0011] According to the axial force adjustment structure of a closed impeller centrifugal compressor in some embodiments of the present application, sealing comb teeth are provided between the rotor component of the adjustment structure and the stator component of the adjustment structure.

[0012] According to the axial force adjustment structure of a closed impeller centrifugal compressor in some embodiments of the present application, the sealing comb teeth are arranged on the stator component of the adjustment structure.

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

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

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

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

[0017] According to the axial force adjustment structure of the closed impeller centrifugal compressor in some embodiments of the present application, the sealing grate teeth include first sealing grate teeth and second sealing grate teeth, the first sealing grate teeth are arranged on the left stator part, and the second sealing grate teeth are arranged on the right stator part.

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

[0019]

[0020] Wherein, S is the area of ​​the leakage flow pressure surface formed between the stator of the regulating structure and the impeller back; r2 is the maximum outer radius of the rotor 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 in the compressor housing, a hub fixedly connected to one end of the compressor main shaft, a wheel cover coaxially arranged with the hub and sleeved on the outside of the hub, a plurality of impeller blades distributed at intervals along the circumference of the hub and connected between the hub and the wheel cover, and also includes the axial force adjustment structure of the closed impeller centrifugal compressor described in any of the above embodiments.

[0022] Beneficial effects of the present invention:

[0023] The present invention adjusts the maximum outer radius of the regulating structure rotor component to adjust the pressure bearing area of ​​the high-pressure leakage flow borne by the closed impeller wheel back, thereby adjusting the axial force borne by the compressor rotor.

[0024] Specifically, the axial force adjustment structure of the closed impeller centrifugal compressor of the present invention includes an impeller wheel back, an adjustment structure stator fixedly connected to the compressor housing, and an adjustment structure rotor fixedly connected to the compressor main shaft and arranged between the adjustment structure stator and the compressor main shaft; a leakage flow pressure surface is formed between the adjustment structure stator and the impeller wheel back; the adjustment structure rotor includes a maximum outer circle radius along the radial direction, and the area of ​​the leakage flow pressure surface can be adjusted by adjusting the size of the maximum outer circle radius. Compared with the conventional closed impeller centrifugal compressor, the pressure area of ​​the high-pressure leakage flow borne by the closed impeller wheel back can be adjusted by adjusting the size of the maximum outer circle radius of the adjustment structure rotor according to the actual operation test results of the compressor, thereby effectively adjusting the axial force borne by the compressor rotor, and ensuring the technical effect of the stability and reliability of the bearing operation of the closed impeller centrifugal compressor under all working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following drawings are used to provide a further understanding of the present application, constitute a part of the present application, and are only intended to provide an illustrative explanation and description of the present invention, and are not intended to limit the scope of the present invention. In the drawings:

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

[0027] Figure 2A schematic diagram of the flow directions of the main flow and the leakage flow in the closed impeller centrifugal compressor according to an embodiment of the present application;

[0028] Figure 3 It is a right view structural schematic diagram of the impeller wheel back and the regulating structure rotor component and the compressor main shaft in some embodiments of the present application;

[0029] Figure 4 This is a schematic diagram of a three-dimensional cross-sectional structure of an adjustment structure rotor component according to some embodiments of the present application.

[0030] Reference numerals:

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

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

[0033] 30. Sealing comb teeth on the impeller wheel cover side; 31. First annular cavity; 32. Second annular cavity. DETAILED DESCRIPTION

[0034] Several embodiments of the present application will be disclosed below with diagrams to clearly and completely describe the technical solution of the present application, which constitute a part of the specification of the present application and are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0035] In this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or apparatus.

[0036] The technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] The following contents are all examples of specific implementation processes provided for describing in detail the technical solutions to be protected by this application. However, this application may also be implemented in other ways different from the descriptions herein. Persons skilled in the art may, under the guidance of the concepts of this application, adopt different technical means to implement this application. Therefore, this application is not limited to the specific embodiments below.

[0038] Figure 1 The schematic diagram of the structure of the axial force regulating structure of a closed impeller centrifugal compressor installed on a closed impeller centrifugal compressor according to an embodiment of the present invention is shown. The closed impeller centrifugal compressor of this embodiment comprises a compressor housing 3, a compressor main shaft 100 located in 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 and an axial force regulating structure distributed along the circumference of the hub 101 and connected between the hub 101 and the wheel cover 12; wherein the impeller 1, the hub 101 and the wheel cover 12 together constitute a closed impeller of the centrifugal compressor, the axial force regulating structure is arranged on the right side of the closed impeller, that is, arranged away from the inlet direction of the centrifugal compressor, and its regulating structure rotor member 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 in the figure, the fluid enters the closed impeller flow channel axially through the centrifugal compressor inlet, and the high-speed rotating closed impeller does work on the fluid, and becomes a high-pressure fluid when it reaches the impeller outlet. The high-pressure fluid at the impeller outlet is divided into a mainstream part and a leakage flow part. The high-pressure airflow of the mainstream part enters the subsequent components such as the diffuser, volute, and return flow device, and part of the leakage flow enters the leakage channel on the impeller wheel cover side, and the other part enters the leakage channel on the back side of the impeller wheel.

[0040] The technical solution of the embodiment of the present application is mainly to control 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, and to design an axial force adjustment structure of the closed impeller centrifugal compressor with a specific structure and function, so as 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 combined with Figure 1-4The axial force adjustment structure of the closed impeller centrifugal compressor according to the embodiment of the present application is described.

[0042] See also Figure 1 In an embodiment of the present application, an axial force adjustment structure of a closed impeller centrifugal compressor is provided, wherein the axial force adjustment structure comprises an impeller back 10, an adjustment structure stator component 21 fixedly connected to the compressor housing, and an adjustment structure rotor component 22 fixedly connected to the compressor main shaft 100 and arranged between the adjustment structure stator component 21 and the compressor main shaft 100; a leakage flow pressure surface 11 is formed between the adjustment structure stator component 21 and the impeller back 10.

[0043] It can be understood that an impeller back leakage channel is formed between the regulating structure stator 21 and the impeller back 10, and the leakage flow pressure surface 11 is a projection of the impeller back leakage channel onto the impeller back surface.

[0044] Combination Figure 2 , Figure 3 As shown, the regulating structure rotor component 22 includes a maximum outer circle radius r2 along the radial direction, and the area of ​​the leakage flow pressure bearing surface is adjusted by adjusting the size of the maximum outer circle radius r2.

[0045] Specifically, the important parameters related to the axial force adjustment structure and the flow path of the high-pressure working fluid gas flow are as follows: Figure 2 As shown, the right view of the closed impeller wheel back and the axial force adjustment structure rotor is as follows Figure 3 As shown in Figure 1, r1 is the radius of the compressor rotor main shaft where the axial force adjustment structure is installed, r2 is the maximum outer radius of the adjustment structure rotor, and r3 is the maximum radius of the impeller wheel back. Since the three key structural parameters satisfy r1<r2<r3, according to Figure 3 The geometric relationship of the closed impeller back is used to calculate the area of ​​the closed impeller back that is subjected to high pressure, that is, the area S1 of the leakage flow pressure surface:

[0046]

[0047] It can be understood that, according to the different axial forces generated by the closed impeller centrifugal compressor under different operating conditions, the above-mentioned key parameter r2 is adjusted to adjust the area of ​​the high-pressure pressure-bearing surface, that is, the area S1 of the leakage flow pressure-bearing surface, thereby adjusting the axial force on the compressor rotor. When the axial force to the left is large, r2 is increased to reduce S1 and reduce the axial force to the left; when the axial force to the right is large, r2 is reduced to increase S1 and increase the axial force to the left. By adjusting r2 to control the maximum axial force of the compressor under different operating conditions to not exceed the allowable range of the bearing, the stability and reliability of the bearing operation of the closed impeller centrifugal compressor under all operating conditions is effectively guaranteed.

[0048] It should be noted that the specific means for adjusting the maximum outer radius r2 of the adjusting structure rotor component 22 in the embodiment of the present application can be achieved by replacing the adjusting structure rotor component with a suitable maximum outer radius according to the actual operation test results of the compressor; or, according to the actual operation test results of the compressor, the maximum outer radius of the adjusting structure rotor component 22 is automatically adjusted in real time; specifically, the axial force adjustment structure of the closed impeller centrifugal compressor also includes: a pressure sensor and a controller are set at the back of the impeller, and a retractable outer surface structure is set for the maximum outer surface structure 221 of the adjusting structure rotor component 22, and the axial pressure data of the leakage flow pressure surface is collected and monitored in real time by the pressure sensor, and based on the real-time monitored axial pressure data, the extension and retraction of the maximum outer surface structure is achieved through the control of the controller, thereby achieving real-time adjustment of the maximum outer radius to adjust the area of ​​the high-pressure pressure surface, and thus being able to adjust the size of the axial force in real time.

[0049] As a preferred embodiment of the axial force adjustment structure of a closed impeller centrifugal compressor, Figure 1 , Figure 2 As shown, the radial cross-section of the regulating structure rotor component 22 is a “Z”-shaped structure, and the “Z”-shaped structure includes a maximum outer circular surface structure 221 and a minimum outer circular surface structure 222 , and 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 at one end thereof, and the vertical table of the Z-shaped structure enclose a first annular cavity 31. The regulating structure stator component 21 includes a left stator portion 211 and a right stator portion 212, and a second annular cavity 32 is formed between the left stator portion 211, the right stator portion 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 of this embodiment are provided to provide a buffer space chamber for the leakage flow and facilitate the realization of lightweight compressor. The right stator part 212 is fixedly connected to the shell of the compressor and can also serve as a supporting structure inside the compressor, and at the same time provides necessary conditions for forming the second annular cavity 32 and assembling the second sealing comb teeth 214.

[0052] Furthermore, sealing grate teeth are provided between the regulating structure rotor component 22 and the regulating structure stator component 21 , and the sealing grate teeth are provided on the arc surface of the regulating structure stator component on one side close to the regulating structure rotor component 22 .

[0053] Furthermore, the sealing grate teeth include first sealing grate teeth 213 and second sealing grate teeth 214 , the first sealing grate teeth 213 are arranged on the left stator portion 211 , and the second sealing grate teeth 214 are arranged on the right stator portion 212 .

[0054] Specifically, the leakage flow entering the leakage channel on the back side of the impeller is first reduced in pressure through the first sealing grate teeth 213, so that the pressure acting on the vertical table 223 of the Z-shaped adjustment structure rotor component is smaller, thereby reducing the axial force acting there, and then the second pressure is reduced through the second sealing grate teeth 214, further reducing the overall leakage flow.

[0055] like Figure 4 The three-dimensional sectional structural diagram of the regulating structure rotor component shown in the figure has a cross-sectional shape similar to a Z-shape, forming two outer cylindrical surfaces with different radii, namely a maximum outer cylindrical surface structure 221 and a minimum outer cylindrical surface structure 222, wherein the position of the minimum outer cylindrical surface structure 222 is basically fixed, and the position of the maximum outer cylindrical surface structure 221 varies with the adjustment of the above-mentioned key parameter r2. While adjusting the maximum outer cylindrical surface structure 221, the radius of the regulating structure stator component 21 and the sealing comb teeth thereof of the axial force regulating structure are correspondingly adjusted to ensure that the sealing gap here remains unchanged, thereby maintaining the pressure drop of the leakage flow here.

[0056] In summary, the axial force adjustment structure of the closed impeller centrifugal compressor of the present invention includes an impeller wheel 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 arranged between the adjustment structure stator 21 and the compressor main shaft 100; a leakage flow pressure surface 11 is formed between the adjustment structure stator 21 and the impeller wheel back 10; the adjustment structure rotor 22 includes a maximum outer circle radius r1 in the radial direction, and the area of ​​the leakage flow pressure surface is adjusted by adjusting the size of the maximum outer circle radius. Compared with the conventional closed impeller centrifugal compressor, the pressure area of ​​the high-pressure leakage flow borne by the closed impeller wheel back can be adjusted by adjusting the size of the maximum outer circle radius of the adjustment structure rotor according to the actual operation test results of the compressor, thereby effectively adjusting the axial force borne by the compressor rotor, and ensuring the technical effect of the stability and reliability of the bearing operation of the closed impeller centrifugal compressor under all working conditions.

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

[0058] The above embodiments 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, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these 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.

[0059] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0060] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A closed impeller centrifugal compressor axial force adjustment structure, characterized in that: include: Impeller back; An adjusting structure stator component, wherein a leakage flow pressure bearing surface is formed between the adjusting structure stator component and the impeller back; The regulating structure rotor component is fixedly connected to the compressor main shaft and is arranged between the regulating structure stator component and the compressor main shaft; the regulating structure rotor component includes a maximum outer circle radius along the radial direction, and the area of ​​the leakage flow pressure bearing surface is adjusted by adjusting the size of the maximum outer circle radius.

2. The axial force adjustment structure of a closed impeller centrifugal compressor according to claim 1, characterized in that: Sealing grate teeth are arranged between the regulating structure rotor component and the regulating structure stator component.

3. The axial force adjustment structure of a closed impeller centrifugal compressor according to claim 2, characterized in that: The sealing comb teeth are arranged on the stator component of the regulating structure.

4. The axial force adjustment structure of a closed impeller centrifugal compressor according to claim 2, characterized in that: The radial cross section of the regulating structure rotor member is a "Z"-shaped structure.

5. The axial force adjustment structure of a closed impeller centrifugal compressor according to claim 4, characterized in that: The "Z"-shaped structure includes a maximum outer cylindrical surface structure and a minimum outer cylindrical surface structure, and the minimum outer cylindrical surface structure is fixedly connected to the compressor main shaft.

6. The axial force adjustment structure of a closed impeller centrifugal compressor according to claim 5, characterized in that: A first annular cavity is formed between the largest outer cylindrical surface structure and the compressor main shaft.

7. The axial force adjustment structure of a closed impeller centrifugal compressor according to claim 5, characterized in that: The stator component of the regulating structure comprises 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 of a closed impeller centrifugal compressor according to claim 7, characterized in that: The sealing grate teeth include first sealing grate teeth and second sealing grate teeth, wherein the first sealing grate teeth are arranged on the left stator portion, and the second sealing grate teeth are arranged on the right stator portion.

9. The axial force adjustment structure of a closed impeller centrifugal compressor according to 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 circle radius is: Wherein, S is the area of ​​the leakage flow pressure surface formed between the stator of the regulating structure and the impeller back; r2 is the maximum outer radius of the rotor 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 in the compressor housing, a hub fixedly connected to one end of the compressor main shaft, a wheel cover coaxially arranged with the wheel hub and sleeved on the outer side of the wheel hub, and a plurality of impeller blades spaced apart along the circumference of the wheel hub and connected between the wheel hub and the wheel cover, characterized in that: It also includes an axial force adjustment structure for a closed impeller centrifugal compressor as described in any one of claims 1-9.

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