Impeller cover sealing structure and centrifugal compressor

Abstract

The utility model discloses an impeller cover sealing structure and a centrifugal compressor, and belongs to the technical field of centrifugal compressors, the impeller cover sealing structure is characterized in that a seal is formed between an impeller cover of an impeller and the inner wall of an air inlet flow channel; comprising a wheel cover seal; the wheel cover seal is fixed and hermetically connected with the inner wall of the air inlet flow channel; the wheel cover seal is provided with a first sealing face, and the first sealing face, the front end face of the wheel cover and an outer circumference sealing face are sealed through a labyrinth structure. The centrifugal compressor comprises an air inlet cylinder, a volute and an impeller, an air inlet flow channel of the air inlet cylinder and a volute flow channel of the volute jointly form an air flow channel, and the impeller is located in the air flow channel. The air inlet flow channel and the impeller cover of the impeller are sealed through the impeller cover sealing structure. According to the impeller cover sealing structure, gas reverse flow in the gas compression process is reduced through matching of few parts; the airflow loss of the centrifugal compressor is reduced, and high efficiency and energy conservation can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of centrifugal compressors, in particular to an impeller cover sealing structure and a centrifugal compressor. Background Art

[0002] During the gas compression process, centrifugal compressors require multiple components mechanically connected to form an airflow channel. These components are collectively referred to as the flow assembly. The most core component is the impeller, which is divided into semi-open impellers and closed impellers depending on their structure. With a closed impeller structure, the impeller experiences internal leakage during operation, with high-pressure air flowing back from the impeller outlet to the impeller inlet along the outside of the impeller cover. Therefore, a shroud seal structure is designed on the outside of the impeller cover to effectively seal the gas, reduce this loss, and thus improve the centrifuge's compression efficiency.

[0003] The commonly used wheel cover sealing structure has a complex structure, uses many parts, is inconvenient to adjust the gap, and has an unstable sealing effect. Utility Model Content

[0004] In order to solve the problems existing in the prior art, the utility model provides an impeller cover sealing structure and a centrifugal compressor. The impeller cover sealing structure can adjust the impeller cover sealing gap by cooperating with fewer parts. The structure is simple, which is not only convenient for disassembly and assembly, but also reduces the assembly difficulty and processing cost.

[0005] In order to achieve the above purpose, the technical solution adopted by the present utility model is as follows:

[0006] On the one hand, the utility model provides an impeller cover sealing structure, which forms a seal between the impeller cover and the inner wall of the inlet flow channel; including a wheel cover seal;

[0007] The wheel cover seal is fixed and sealed to the inner wall of the intake air duct;

[0008] The wheel cover seal has a first sealing surface, and the first sealing surface forms a seal with the front end surface and the outer circumferential sealing surface of the wheel cover using a comb tooth structure.

[0009] As a preferred technical solution, the wheel cover seal includes a first sealing part and a second sealing part; the first sealing part forms a seal with the inner wall of the intake air duct and the front end face of the wheel cover; the second sealing part forms a seal with the outer circumferential sealing surface of the wheel cover.

[0010] As a preferred technical solution, the side of the second sealing portion facing the outer circumferential sealing surface is a second grate surface, and the second grate grooves on the second grate surface are arranged obliquely, so that in the flow direction of the countercurrent gas between the wheel cover and the inner wall of the intake air duct, the inner end of the second grate groove is located upstream of the outer end;

[0011] And / or, the side surface of the first sealing portion facing the front end surface is a first grate surface, and the first grate groove on the first grate surface is arranged obliquely, and in the flow direction of the countercurrent gas between the wheel cover and the inner wall of the intake air duct, the inner end of the first grate groove is located on the upstream side of the outer end.

[0012] As a preferred technical solution, the first sealing portion and the second sealing portion are sealed to each other, and a positioning structure and / or a sealing element is provided between the first sealing portion and the second sealing portion.

[0013] As a preferred technical solution, the outer circumferential sealing surface is connected to the front end surface;

[0014] And / or, the wheel cover seal is made of aluminum alloy;

[0015] And / or, the outer side surface of the outer circumferential sealing surface protruding from the wheel cover is a conical surface;

[0016] And / or, the outer circumferential sealing surface has a plurality of stepped sealing annular surfaces;

[0017] And / or, a plurality of grate teeth are machined on the first sealing surface, and the thickness of the grate teeth increases with the increase of the distance from the wheel cover;

[0018] And / or, a wheel cover seal adjustment pad is provided between the wheel cover seal and the inner wall of the intake air duct.

[0019] As a preferred technical solution, the rear end of the intake air duct is provided with a second avoidance portion, the second avoidance portion has a first intake cylinder sealing surface, and the first intake cylinder sealing surface is opposite to the front end surface; the wheel cover seal has a second sealing surface, and the second sealing surface forms a seal with the first intake cylinder sealing surface.

[0020] As a preferred technical solution, the first air inlet cylinder sealing surface is flat and parallel to the front end surface;

[0021] And / or, the second avoidance portion is provided with a first guide surface, the wheel cover seal has a second guide surface, and the second guide surface cooperates with the first guide surface to position and guide the wheel cover seal.

[0022] As a preferred technical solution, the first guide surface and the second guide surface are both cylindrical surfaces and are coaxial with the rotation axis of the impeller.

[0023] On the other hand, the utility model provides a centrifugal compressor, including an intake cylinder, a volute and an impeller, wherein the intake flow channel of the intake cylinder and the volute flow channel of the volute together form an air flow channel, and the impeller is located in the air flow channel; the intake flow channel and the impeller cover are sealed by the above-mentioned impeller cover sealing structure.

[0024] As a preferred technical solution, the invention further includes a diffuser, wherein a first avoidance portion is provided on the second guide wall at the air inlet end of the volute flow passage, the first avoidance portion being close to the impeller and recessed toward the interior of the second guide wall; the first avoidance portion is annular and coaxial with the rotation axis of the impeller, and the diffuser is installed in the first avoidance portion;

[0025] And / or, the intake cylinder is made of cast iron or cast steel.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1) The wheel cover seal is not only fixed and sealed to the inner wall of the intake air duct, but also forms a seal with the front end face and outer circumferential sealing surface of the wheel cover. The sealing form is a grate seal. With fewer parts, it can reduce gas backflow during the gas compression process.

[0028] 2) By controlling the thickness of the wheel cover seal adjustment plate, the sealing gap can be effectively adjusted to achieve a better sealing effect; as the thickness of the wheel cover seal adjustment plate increases, the sealing gap decreases and the gas leakage continues to decrease;

[0029] 3) The centrifugal compressor adopting the above structure reduces airflow loss and can achieve high efficiency and energy saving. At the same time, the number of parts is reduced through structural optimization, which not only reduces manufacturing costs but also reduces assembly difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the overall structure of the first embodiment of the centrifugal compressor of the present utility model;

[0031] Figure 2 for Figure 1 Enlarged view of area A in the middle;

[0032] Figure 3 FIG1 is a schematic diagram of the overall structure of a second embodiment of the centrifugal compressor of the present invention;

[0033] Figure 4 for Figure 3 Enlarged view of area B in the middle;

[0034] Figure 5 FIG1 is a schematic diagram of the overall structure of a third embodiment of the centrifugal compressor of the present utility model;

[0035] Figure 6 for Figure 5 Magnified view of area C in the middle.

[0036] In the picture:

[0037] 1-intake cylinder; 11-intake flow passage; 12-second avoidance portion; 13-first intake cylinder sealing surface; 14-first guide surface; 15-threaded hole;

[0038] 2-volute; 21-volute flow passage; 22-first avoidance portion;

[0039] 3-Diffuser;

[0040] 4-Impeller; 41-Impeller disc; 42-Impeller cover; 43-Outer circumferential sealing surface; 44-Front end face

[0041] 5-wheel cover seal adjustment plate;

[0042] 6 - wheel cover seal; 61 - first sealing surface; 62 - through hole; 63 - second guide surface; 64 - second sealing surface; 65 - first sealing portion; 651 - first grate tooth surface; 652 - first grate tooth groove; 66 - second sealing portion; 661 - second grate tooth surface; 662 - second grate tooth groove; 67 - positioning structure; 68 - sealing element;

[0043] 7-Locking piece. DETAILED DESCRIPTION

[0044] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0045] Please refer to Figure 1 , is an embodiment of a centrifugal compressor provided by the present invention, comprising an intake cylinder 1, a volute 2, an impeller 4 and a wheel cover seal 6. The impeller 4 is a closed impeller, and the structure of the impeller 4 can be referred to Figure 2 , including a wheel disc 41 and a wheel cover 42. In the following description, along the direction of airflow in the impeller 4, the part that the airflow passes through first is the front, and the part that the airflow passes through later is the rear; for example, the air inlet end of the impeller 4 is called the front end, and the air outlet end is called the rear end. The air intake cylinder 1 is mounted on the volute 2 by fasteners, and the fasteners can be bolt and nut assemblies. There is an air intake channel 11 in the air intake cylinder 1, and a volute channel 21 in the volute 2. The air intake channel 11 and the volute channel 21 together form an airflow channel for airflow circulation. The impeller 4 is located in the airflow channel to pressurize the airflow. The assembly structure of the impeller 4 and the volute 2 is prior art, so it is not shown in the figure and will not be repeated here. As one of the implementation methods of the air flow channel, the inlet flow channel 11 is connected to the air inlet end of the impeller 4, and the inlet flow channel 11 plays a role in guiding the air flow to evenly enter the impeller 4; the wheel 41 rotates at high speed to do work on the gas to obtain high-speed and high-pressure gas; the high-speed and high-pressure gas discharged from the impeller 4 is collected in the volute flow channel 21 of the volute 2, and finally introduced into the user pipeline or enters the next stage for further compression, thus completing the first-stage gas compression.

[0046] Furthermore, the centrifugal compressor also has a diffuser 3, which is located at the inlet end of the volute flow passage 21. After the gas flowing out of the impeller 4 flows through the diffuser 3, the flow rate of the gas is reduced and further pressurized. The diffuser 3 is installed inside the volute 2 by fasteners.

[0047] The impeller 41 and the wheel cover 42 form an impeller flow channel inside. The airflow entering the impeller flow channel from the inlet flow channel 11 becomes a high-speed and high-pressure airflow and then flows into the volute flow channel 21. Hereinafter, the side of the impeller 41 facing the impeller flow channel is called the impeller guide surface, and the side of the wheel cover 42 facing the impeller flow channel is called the wheel cover guide surface. The air inlet end of the volute flow channel 21 has two side walls, one of which is connected to the wheel cover guide surface, and the other side wall is connected to the impeller guide surface. Hereinafter, the side wall connected to the wheel cover guide surface is called the first guide wall, and the side wall connected to the impeller guide surface is called the second guide wall. Preferably, one way to assemble the diffuser 3 and the volute flow channel 21 is that a first avoidance portion 22 is provided on the second guide wall, the first avoidance portion 22 is close to the impeller 41 and is recessed into the interior of the second guide wall; the first avoidance portion 22 is annular and coaxial with the rotation axis of the impeller 4, and the diffuser 3 is installed in the first avoidance portion 22.

[0048] Inlet cylinder 1 can be made of cast iron or cast steel to meet the requirements of high-speed, high-pressure gas delivery. During compressed air delivery, the gas pressure at the rear end of impeller 4 is greater than that at the front end of impeller 4, causing the gas at the rear end of impeller 4 to flow back along the outside of impeller cover 42. This means that the gas flows back from back to front along the assembly gap between impeller cover 42 and inlet cylinder 1, which is gas leakage. To control gas leakage, a wheel cover seal 6 is installed between wheel cover 42 and inlet cylinder 1.

[0049] The first embodiment of the wheel cover seal 6 can be referred to Figure 1 and Figure 2 The wheel cover seal 6 is fixedly mounted on the intake cylinder 1, forming a fixed seal with the inner wall of the intake air duct 11 to prevent the airflow from flowing back from the assembly gap between the wheel cover seal 6 and the inner wall of the intake air duct 11. Preferably, the wheel cover seal 6 is mounted on the intake cylinder 1 via a locking member 7. Specifically, a threaded hole 15 is machined on the inner wall of the intake air duct 11, and a through hole 62 is machined in the wheel cover seal 6. The locking member 7 is a bolt and is located in the through hole 62. The wheel cover seal 6 is mounted on the intake cylinder 1 through the threaded connection between the bolt and the threaded hole 15. The locking member 7 can also adopt an existing detachable structure such as a clip-on form to achieve a fixed connection between the wheel cover seal 6 and the inner wall of the intake air duct 11.

[0050] Furthermore, in order to adapt to the installation of the wheel cover seal 6, a second avoidance portion 12 is provided on the inner wall of the rear end of the intake air duct 11, and the second avoidance portion 12 is recessed into the intake cylinder 1; the second avoidance portion 12 has a first intake cylinder sealing surface 13, and the first intake cylinder sealing surface 13 is opposite to the front end surface 44 of the wheel cover 42; preferably, the first intake cylinder sealing surface 13 is flat and parallel to the front end surface 44, and the threaded hole 15 required for the installation of the aforementioned wheel cover seal 6 can also be arranged on the first intake cylinder sealing surface 13.

[0051] The wheel cover seal 6 has a first sealing surface 61 and a second sealing surface 64. The first sealing surface 61 forms a seal with both the front end face 44 and the outer circumferential sealing surface 43 of the wheel cover 4 using a grate structure. The reflux gas forms a strong vortex within the cavity formed by the grate structure, thus providing a seal. The second sealing surface 64 forms a seal with the first intake cylinder sealing surface 13. Because the front end face 44 and the outer circumferential sealing surface 43 are not coplanar but nearly perpendicular, the first sealing surface 61 forms a labyrinth seal with both the front end face 44 and the outer circumferential sealing surface 43. This not only provides a throttling effect but, combined with the grate seal, significantly reduces backflow and improves the sealing effect.

[0052] Furthermore, the outer circumferential sealing surface 43 is connected to the front end surface 44; the outer circumferential sealing surface 43 protrudes from the outer side surface of the wheel cover 42 and is a conical surface; the outer circumferential sealing surface 43 has a plurality of stepped sealing annular surfaces. A plurality of comb teeth are processed on the first sealing surface 61, and the comb teeth cooperate with the sealing annular surface to achieve sealing. Preferably, the thickness of the comb teeth increases with the increase of the distance from the wheel cover 42. The wall thickness of the comb teeth near the wheel cover 42 is thinner, and the damage to the wheel cover 42 is small when colliding with the wheel cover 42. It should be noted here that the thickness of the comb teeth refers to the size of the comb teeth in the axial direction of the wheel cover seal 6.

[0053] Within a certain range, the grate seal's sealing gap significantly affects leakage. Even small adjustments to the gap can lead to significant changes in leakage. When the gap reaches a certain size, the change in leakage with the gap is not significant. At this point, it can be assumed that the grate seal has virtually no effect on sealing gas. As the wheel cover 42 and the first sealing surface 61 wear, the gap between them gradually increases, reducing the sealing effect and even rendering it ineffective. To ensure a reliable seal, a wheel cover seal adjustment plate 5 is provided between the wheel cover seal 6 and the intake cylinder 1. By selecting a wheel cover seal adjustment plate 5 of appropriate thickness, the sealing gap between the first sealing surface 61 and the front end face 44 and the outer circumferential sealing surface 43 can be controlled. To adjust the axial gap between the wheel cover seal 6 and the wheel cover 42, the wheel cover seal 6 can be removed and replaced with a thicker wheel cover seal adjustment plate 5 or a thinner one, effectively controlling gas leakage during the compression process.

[0054] Furthermore, the second avoidance portion 12 is provided with a first guide surface 14, which is a cylindrical surface and is coaxial with the rotation axis of the impeller 4; the wheel cover seal 6 has a second guide surface 63, which is in contact with the first guide surface 14, and can position and guide the wheel cover seal 6 during the replacement and installation of the wheel cover seal adjustment pad 5.

[0055] The wheel cover seal 6 can be made of aluminum alloy, and the impeller 4 is generally made of carbon steel, plastic steel, cast iron, stainless steel and other materials with greater hardness; therefore, even if the impeller 4 vibrates too much and collides with the grate teeth of the sealed airflow, the impeller 4 will not be damaged.

[0056] The second embodiment of the wheel cover seal 6 can be referred to Figure 3 and Figure 4 The wheel cover seal 6 includes a first sealing portion 65 and a second sealing portion 66. The first sealing portion 65 forms a seal with the intake cylinder 1 and the front end face 44, while the second sealing portion 66 forms a seal with the outer circumferential sealing surface 43. The first sealing portion 65 and the second sealing portion 66 are connected and sealed to each other. After the first sealing portion 65 and the second sealing portion 66 are stacked, they are installed on the intake cylinder 1 via the locking member 7.

[0057] Specifically, the side of the second sealing portion 66 facing the outer circumferential sealing surface 43 is a second grate surface 661. The second grate groove 662 on the second grate surface 661 is tilted, with the inner end of the second grate groove 662 close to the outer circumferential sealing surface 43 and the outer end extending into the second sealing portion 66. In the flow direction of the countercurrent gas between the wheel cover 42 and the intake cylinder 1, the inner end of the second grate groove 662 is located upstream of the outer end. The side of the first sealing portion 65 facing the front end surface 44 is a first grate surface 651. The first grate groove 652 on the first grate surface 651 is also tilted, with the inner end of the first grate groove 652 close to the front end surface 44 and the outer end extending into the first sealing portion 65. In the flow direction of the countercurrent gas between the wheel cover 42 and the intake cylinder 1, the inner end of the first grate groove 652 is located upstream of the outer end.

[0058] When one of the second grate tooth surface 661 and the first grate tooth surface 651 is severely worn, simply replacing the wheel cover seal adjustment plate 5 cannot take into account both the sealing gap between the second grate tooth surface 661 and the outer circumferential sealing surface 43 and the gap between the first grate tooth surface 651 and the front end face 44, and a conflict may be encountered; for example, when the second grate tooth surface 661 is severely worn and the first grate tooth surface 651 is not worn, the gap between the second grate tooth surface 661 and the outer circumferential sealing surface 43 becomes larger, and the gap between the first grate tooth surface 651 and the front end face 44 does not change, so it is only necessary to adjust the gap between the second grate tooth surface 661 and the outer circumferential sealing surface 43 and increase the thickness of the wheel cover seal adjustment plate 5, but this will also cause the gap between the first grate tooth surface 651 and the front end face 44 to become smaller or even interfere, which is different from the actual adjustment requirements. The first sealing surface 61 is split, and the second grate surface 661 and the first grate surface 651 together constitute the first sealing surface 61 . In this way, the first sealing portion 65 or the second sealing portion 66 can be replaced separately.

[0059] The third embodiment of the wheel cover seal 6 can be referred to Figure 5 and Figure 6 To ensure assembly accuracy, a positioning structure 67 is provided between the first sealing portion 65 and the second sealing portion 66. Hereinafter, the opposing sides of the first sealing portion 65 and the second sealing portion 66 are referred to as the abutment surfaces. As one embodiment of the positioning structure 67, a raised ring is machined on the abutment surface of the first sealing portion 65, and a groove is machined on the abutment surface of the second sealing portion 66. The raised ring engages with the groove to achieve radial positioning of the first and second sealing portions 65, 66. Positioning structure 67 can also employ a pin, pin hole, or other positioning structure.

[0060] To ensure a good seal, a sealing element 68 is provided on the mating surfaces of the first sealing portion 65 and the second sealing portion 66. Accordingly, to facilitate the positioning and installation of the sealing element 68, a sealing groove is provided on the mating surface of the first sealing portion 65 and / or the mating surface of the second sealing portion 66. The sealing element 68 can be a sealing ring, which is located within the sealing groove. The model and specifications of the sealing ring can be selected as needed.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An impeller cover sealing structure, forming a seal between the impeller cover (42) of the impeller (4) and the inner wall of the inlet flow channel (11); characterized in that: including a wheel cover seal (6); The wheel cover seal (6) is fixedly and sealingly connected to the inner wall of the intake air duct (11); The wheel cover seal (6) has a first sealing surface (61), and the first sealing surface (61) forms a seal with the front end surface (44) and the outer circumferential sealing surface (43) of the wheel cover (42) using a comb tooth structure.

2. The impeller cover sealing structure according to claim 1, characterized in that: The wheel cover seal (6) includes a first sealing portion (65) and a second sealing portion (66); the first sealing portion (65) forms a seal with the inner wall of the intake air duct (11) and the front end surface (44) of the wheel cover (42); and the second sealing portion (66) forms a seal with the outer circumferential sealing surface (43) of the wheel cover (42).

3. The impeller cover sealing structure according to claim 2, characterized in that: The side of the second sealing portion (66) facing the outer circumferential sealing surface (43) is a second grate surface (661), and the second grate groove (662) on the second grate surface (661) is arranged obliquely, and in the flow direction of the countercurrent gas between the wheel cover (42) and the inner wall of the intake flow channel (11), the inner end of the second grate groove (662) is located on the upstream side of the outer end; And / or, the side surface of the first sealing portion (65) facing the front end surface (44) is a first grate surface (651), and the first grate groove (652) on the first grate surface (651) is arranged obliquely, and in the flow direction of the countercurrent gas between the wheel cover (42) and the inner wall of the intake air duct (11), the inner end of the first grate groove (652) is located on the upstream side of the outer end.

4. The impeller cover sealing structure according to claim 2, characterized in that: The first sealing portion (65) and the second sealing portion (66) are sealed to each other, and a positioning structure (67) and / or a sealing element (68) is provided between the first sealing portion (65) and the second sealing portion (66).

5. The impeller cover sealing structure according to claim 1, characterized in that: The outer circumferential sealing surface (43) is connected to the front end surface (44); And / or, the wheel cover seal (6) is made of aluminum alloy; And / or, the outer side surface of the outer circumferential sealing surface (43) protruding from the wheel cover (42) is a conical surface; And / or, the outer circumferential sealing surface (43) has a plurality of stepped sealing annular surfaces; And / or, a plurality of grate teeth are machined on the first sealing surface (61), and the thickness of the grate teeth increases as the distance from the wheel cover (42) increases; And / or, a wheel cover seal adjustment pad (5) is provided between the wheel cover seal (6) and the inner wall of the intake air duct (11).

6. The impeller cover sealing structure according to claim 1, characterized in that: The rear end of the intake air passage (11) is provided with a second avoidance portion (12), the second avoidance portion (12) having a first intake cylinder sealing surface (13), the first intake cylinder sealing surface (13) being opposite to the front end surface (44); the wheel cover seal (6) having a second sealing surface (64), the second sealing surface (64) forming a seal with the first intake cylinder sealing surface (13).

7. The impeller cover sealing structure according to claim 6, characterized in that: The first air inlet cylinder sealing surface (13) is a plane and parallel to the front end surface (44); And / or, the second avoidance portion (12) is provided with a first guide surface (14), the wheel cover seal (6) has a second guide surface (63), and the second guide surface (63) cooperates with the first guide surface (14) to position and guide the wheel cover seal (6).

8. The impeller cover sealing structure according to claim 7, characterized in that: The first guide surface (14) and the second guide surface (63) are both cylindrical surfaces and are coaxial with the rotation axis of the impeller (4).

9. A centrifugal compressor comprising an intake cylinder (1), a volute (2) and an impeller (4), wherein the intake flow passage (11) of the intake cylinder (1) and the volute flow passage (21) of the volute (2) together form an air flow passage, and the impeller (4) is located in the air flow passage; characterized in that: The inlet flow channel (11) and the impeller cover (42) of the impeller (4) are sealed by the impeller cover sealing structure according to claim 1.

10. A centrifugal compressor according to claim 9, characterized in that: The invention also includes a diffuser (3), wherein a first avoidance portion (22) is provided on the second guide wall at the air inlet end of the volute flow passage (21), the first avoidance portion (22) being close to the wheel disc (41) and recessed toward the interior of the second guide wall; the first avoidance portion (22) is annular and coaxial with the rotary axis of the impeller (4), and the diffuser (3) is installed in the first avoidance portion (22); And / or, the air intake cylinder (1) is made of cast iron or cast steel.

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