Multistage centrifugal compressor

Abstract

This application relates to a multistage centrifugal compressor having a shaft (2) with multiple blades (3) mounted in a housing (4) by bearings (7), characterized in that at least one bearing is provided with a bearing damping element (10) consisting of a ring (11) arranged between the shaft or housing and the bearing, the ring including multiple slits (12) passing through the thickness of the ring in the axial direction (X-X') and at a distance from the radial inner surface (13a) and radial outer surface (13b) of the ring, wherein, option A: the slits are filled with liquid and the axial annular surface (16) of the ring is closed by a protective cover (17); or option B: at least one of the two axial annular surfaces of the ring is provided with a viscoelastic material or hysteresis damping material sandwiched between two concentric disks (21) or the like, the disks being attached to the ring; or option C: the slits are filled with a viscoelastic material.

Description

Technical Field

[0001] This invention relates to a multistage centrifugal compressor. Background Technology

[0002] It is known that in this type of compressor, multiple blades constituting different stages of the compressor are mounted on a shaft, which is supported in the housing by journals.

[0003] Typically, compressors use roller bearings because a typical speed of 50Hz or 60Hz is not too high.

[0004] The maximum number of blades on the shaft (i.e., the maximum number of stages) and the maximum speed at which the blades can rotate are determined by rotor dynamics. More specifically, the first critical lateral velocity constitutes the absolute upper limit of the rotational speed.

[0005] If the mass is too large or the shaft is too long, resonance may occur, producing vibrations close to the natural frequency, but which cannot be exceeded. This problem primarily occurs in rolling bearings, and to a lesser extent in sliding or fluid bearings. The lack of sufficient damping to exceed the critical speed is the main cause of this limitation.

[0006] Therefore, the speed and the number of blades (i.e., stages) are limited by dynamics and the resulting resonance problems.

[0007] It is known that the maximum number of stages in a multistage centrifugal compressor is limited to a number that varies depending on the power variant.

[0008] To address the resonance problem, thin-film dampers, or so-called "extruded membrane dampers," are known.

[0009] These are based on the damping effect of liquids (usually oil) in thin gaps.

[0010] Such thin-film dampers are known, for example, from WO 2019 / 002959.

[0011] The drawback of this known damper is that an oil supply to the thin-film damper is required.

[0012] This means that to achieve this oil supply, there must be oil lines, oil reservoirs, and oil pumps.

[0013] Since multistage centrifugal compressors that use roller bearings do not have oil pumps in most cases, but since bearings are usually grease-lubricated or lubricated by the principle of "splash lubrication", using such a damper means additional costs and larger and more complex machines.

[0014] Therefore, this type of damper is not used in known multistage centrifugal compressors, thus limiting the compressor's speed and number of stages. Summary of the Invention

[0015] The object of this invention is to provide a solution for overcoming at least one of the above-mentioned disadvantages and other disadvantages.

[0016] Therefore, the present invention relates to a multi-stage centrifugal compressor having a shaft with multiple blades, wherein the shaft is mounted in a housing by bearings, characterized in that at least one bearing has a bearing damping element, the bearing damping element being composed of a ring arranged between the shaft or housing and the bearing, wherein the ring includes a plurality of slits extending axially through the thickness of the ring and at a certain distance from the radially inner and radially outer surfaces of the ring, wherein the slits at least partially overlap, wherein:

[0017] Option A: The slit is filled with liquid, which passes through the axial annular surface of the protective cap closure ring;

[0018] or:

[0019] Option B: At least one of the two axial annular surfaces of the ring is provided with a viscoelastic or hysteresis-damping material sandwiched between two concentric disks or similar objects attached to the ring;

[0020] or:

[0021] Option C: The slit is filled with a viscoelastic material.

[0022] The slit's construction forms a radial spring mechanism. The spring constant of this mechanism determines the location of the critical speed. This is chosen somewhere within the machine's speed range. To amplify speeds exceeding the critical speed (i.e., vibrations) with limited dynamic range, damping is added to the elastic element via one of options A, B, or C.

[0023] Here, "overlap" means that a line starting from the midpoint or center of the ring and intersecting the ring will intersect the corresponding slit.

[0024] The term "slit" here refers to a narrow opening, crack, cut, or similar feature, where it is important that these slits extend axially through the entire thickness of the ring.

[0025] The advantage is that a bearing damping element is created, eliminating the need to inject liquid into the slit, thus eliminating the need for associated liquid circuits, liquid pumps, or reservoirs.

[0026] Therefore, bearing damping elements can be easily applied to multi-stage centrifugal compressors.

[0027] By applying bearing damping elements, resonance problems can be avoided, allowing the machine to rotate faster and / or by providing additional stages by setting extra blades on the shaft.

[0028] Although there is liquid in the slit for option A, it is not necessary to continuously replenish the liquid, as the protective cap will keep the liquid in the slit.

[0029] In this paper, it is not excluded that there may be a space filled with liquid between the axial annular surfaces of the protective cap and the ring.

[0030] The protective cover can be designed in different ways and is preferably made of an elastomer (such as rubber).

[0031] For example, the protective cover can be a 3D printed structure with a certain degree of flexibility, or it can be a thin-walled protective cover with a harmonica-like structure.

[0032] However, it should be clear that many different variations are possible.

[0033] For option B, viscoelastic materials (such as rubber) or hysteresis damping materials (such as metal mesh) are arranged parallel to the ring by means of two concentric disks or the like.

[0034] In addition, the concentric disks can be implemented in different ways, but in the simplest embodiment they are two flat disks that can be fixed to the ring, for example, by means of screws or bolts.

[0035] Therefore, such concentric disks can be provided on the axial annular surface on one side or both sides of the ring, with viscoelastic or hysteresis damping material disposed between the concentric disks.

[0036] The viscoelastic material can be, for example, an O-ring, and the hysteresis damping material can be, for example, a metal mesh (“wire mesh”).

[0037] It is important to note that in this case, fluid is usually not needed if the damping is sufficient, but this can still be combined with the presence of fluid in the small gap to increase damping. In this way, oil damping is combined with rubber seals.

[0038] Additionally, for option C, no liquid is present. The viscoelastic material disposed in the slit is preferably rubber attached to the slit through vulcanization.

[0039] The slit is preferably completely filled with a viscoelastic material.

[0040] According to one embodiment, in option A, the protective cover is made of an elastomer.

[0041] According to one embodiment, in option A, the protective cover is a flexible 3D-printed structure.

[0042] According to one embodiment, in option A, the protective cover is a thin-walled protective cover having a harmonica-like structure.

[0043] According to one embodiment, in option B, there is no liquid in the slit.

[0044] According to one embodiment, in option B, the viscoelastic material includes an O-ring, or the hysteresis damping material includes a metal mesh.

[0045] According to one embodiment, both axial annular surfaces of the ring are provided with viscoelastic material or hysteresis damping material.

[0046] According to one embodiment, in option C, the viscoelastic material is rubber attached to the slit by vulcanization.

[0047] According to one embodiment, the bearing is a rolling bearing.

[0048] According to one embodiment, the bearing at only one end of the shaft has a bearing damping element.

[0049] According to one embodiment, the bearing damping element is located on the non-driven end of the shaft.

[0050] According to one embodiment, the liquid is oil.

[0051] According to one embodiment, the ring includes at least three slits.

[0052] According to one embodiment, the slit has a damping portion, the maximum width of which is 0.5 mm, or 0.2 mm, or 1.15 mm.

[0053] According to one embodiment, the slit has a spring portion, the minimum width of which is 0.5 mm.

[0054] According to one embodiment, the shaft has more than ten blades. Attached Figure Description

[0055] To better illustrate the features of the present invention, several preferred embodiments of the multi-stage centrifugal compressor of the present invention are described below as non-limiting examples with reference to the accompanying drawings, wherein:

[0056] Figure 1 A multi-stage centrifugal compressor according to the present invention is schematically illustrated;

[0057] Figure 2 yes Figure 1 The actual embodiment shown in section F2;

[0058] Figure 3 Showing from Figure 2 A practical embodiment of the ring of the bearing damping element;

[0059] Figure 4 Showing more details Figure 2 Bearing damping elements;

[0060] Figure 5 and Figure 6 It shows Figure 4Two variations. Detailed Implementation

[0061] exist Figure 1 The multi-stage centrifugal compressor 1 according to the present invention is schematically shown in the figure.

[0062] A multistage centrifugal compressor basically includes a shaft 2 with multiple blades 3, wherein the shaft 2 is rotatably mounted in a housing 4.

[0063] In this example, there are eight blades 3, but it is possible that there are more than eight or even more than ten blades 3.

[0064] As is known, the outer casing 2 has an inlet 5 and an outlet 6.

[0065] The journals of shaft 2 are supported on both sides by bearings 7.

[0066] In this example, bearing 7 is a rolling bearing, specifically a double-row deep groove ball bearing.

[0067] One end 8 of shaft 2 is the driven end 8, that is, a driver (e.g., a driver in the form of a motor) is connected to this end to enable shaft 2 to rotate. The driver is not shown in the figure.

[0068] The other end 9 of shaft 2 is the non-driven end.

[0069] According to the present invention, at least one bearing 7 is provided with a bearing damping element 10.

[0070] In this example, but not necessarily for the present invention, the bearing damping element 10 is provided only at one end 9 of the shaft 2.

[0071] In this example, this involves the non-driven end 9 of shaft 2.

[0072] The advantage of doing this is that it simplifies the maintenance of the bearing damping element 10.

[0073] Of course, it is possible that bearing damping elements 10 are provided at both ends 8 and 9 of the shaft 2.

[0074] exist Figure 2 The diagram shows a bearing 7 on the non-driven end 9 of the shaft with a bearing damping element 10.

[0075] According to the present invention, the bearing damping element 10 is composed of a ring 11, which is arranged between the housing 4 and the corresponding bearing 7. Of course, it is not excluded that the bearing damping element 10 is arranged between the shaft 2 and the bearing 7.

[0076] Figure 3 Ring 11 is shown in detail.

[0077] The ring 11 includes a plurality of slits 12 that pass through the thickness of the ring 11 along the axial direction X-X' and are spaced apart from the radial inner surface 13a and the radial outer surface 13b of the ring 11.

[0078] Preferably, there are at least three slits 12, wherein at least half of the slits 12 have one or more damping portions 14a, the maximum width of the damping portions 14a being 0.5 mm, preferably 0.2 mm, and more preferably 1.15 mm.

[0079] The damping portions 14a are preferably concentric and do not overlap each other.

[0080] These damping portions 14a preferably surround more than 80% and more preferably more than 90% of the center or midpoint 15 of the ring.

[0081] In addition to the damping portion 14a, preferably at least one slit 12 also has one or more spring portions 14b, the minimum width of which is greater than preferably at least 0.5 mm.

[0082] The width of the spring portion 14b is preferably at least twice, more preferably at least three times, the width of the damping portion 14a.

[0083] According to the invention, the slits 12 at least partially overlap each other.

[0084] As already mentioned, “overlapping slits” here refers to lines that start from the midpoint or center of ring 11 and intersect ring 11, which will intersect the corresponding slit 12.

[0085] "At least partially" means that the slits 12 overlap each other at least a portion of their length, but not necessarily over their entire length.

[0086] Preferably, the spring portion 14b of the slit 12 at least partially overlaps with the damping portion 14a.

[0087] In addition, the damping part 14a is preferably further away from the center or midpoint 15 of the ring 11 than the spring part 14b.

[0088] Another embodiment of ring 11 may include a slit 12 having only a damping portion 14a or only a spring portion 14b. As will be explained below, the embodiment having only a damping portion 14a will preferably be used with option A to produce a "squeezed film" effect. In the cases of options B and C, this thin damping portion 14a is almost useless because the damping is achieved parallel to the slit 12. In this example, the embodiment where the slit 12 has only a spring portion 14b will be preferred, and the spring portion will primarily have an elastic effect.

[0089] The narrower or thinner damping section 14a is preferably manufactured by a wire spark process such as 'EDM' or 'electrical discharge machining'.

[0090] The wider spring portion 14b can be manufactured using water jetting or milling processes.

[0091] For other embodiments of the bearing damping element 10, several options exist according to the present invention, which are... Figures 4 to 6 As shown in the image.

[0092] like Figure 4 As shown, according to the first option A of the invention, there is an embodiment in which the slit 12 is filled with a liquid. This liquid has viscous properties, for example (but not necessarily) oil.

[0093] The axial annular surface 16 of the ring 11 is closed by the protective cover 17.

[0094] In the example shown, the protective cover 17 is made of an elastomer, such as rubber.

[0095] The protective cover 17 is fastened to the axial annular surface 16 of the ring 11 by bolts or screws 18.

[0096] Of course, other fastening methods are also acceptable, as long as they do not impede the elastic effect and therefore do not impede the damping.

[0097] There is a liquid-filled space 19 between the protective cover 17 and the axial annular surface 16 of the ring.

[0098] Alternatively, the protective cover 17 can be a 3D printed structure with a certain degree of flexibility.

[0099] This means that the protective cover 17 is flexible or deformable due to its structure.

[0100] As is well known, 3D printing can achieve complex structures and shapes, thus creating structures with the necessary flexibility.

[0101] For example, the protective cover 17 can be a thin-walled protective cover with a harmonica-like structure. It is well known that such a harmonica-like structure is flexible and deformable.

[0102] like Figure 5 and Figure 6 As shown, according to the second option B of the invention, at least one of the two axial annular surfaces 16 of the ring 11 is provided with a viscoelastic or hysteretic damping material 20 sandwiched between two concentric disks 21 or the like, the disks 21 being attached to the ring 11.

[0103] Like the protective cover 17, the disc 21 can be secured with bolts or screws 18 or in some other way.

[0104] The disk 21 can be implemented in a variety of different forms.

[0105] exist Figure 5 and Figure 6 In the disc 21, there is a slightly irregular radial inner surface or radial outer surface 22 to accommodate a viscoelastic material or a hysteresis damping material 20.

[0106] For option B, the liquid does not need to be present in slit 12.

[0107] The viscoelastic material can be an O-ring 23, such as Figure 5 As shown; and the hysteresis damping material can be metal mesh 24 (or "wire mesh"), such as Figure 6 As shown.

[0108] Despite Figure 5 and Figure 6 In the ring 11, the concentric disk 21 with viscoelastic material or hysteresis damping material 20 is only attached to one side of the ring 11, but it is not excluded that both axial annular surfaces 16 of the ring 11 are provided with viscoelastic material or hysteresis damping material 20.

[0109] Option C, not shown in the figure, relates to an embodiment in which slit 12 is filled with a viscoelastic material.

[0110] The viscoelastic material is, for example, rubber, which is attached to the slit 12 by vulcanization.

[0111] The slit 12 has only the spring part 14b.

[0112] The advantage of this embodiment is that it eliminates the need to attach the protective cover 17 or the concentric disc 21 to the ring 11.

[0113] The operation of the multistage centrifugal compressor 1 is very simple and is described below.

[0114] During the operation of centrifugal compressor 1, the drive will rotate shaft 2, so that blades 3 will draw in air through inlet 5, the air is gradually compressed, and then leaves centrifugal compressor 1 through outlet 6.

[0115] Vibrations will occur during operation, and these vibrations should be damped to ensure that resonance problems do not occur.

[0116] The bearing damping element 10 will dampen these vibrations.

[0117] exist Figure 4 In this case, the liquid in slit 12 will create a thin film damping, which will provide damping.

[0118] The protective cap 17 keeps the liquid in the slit 12 so that the liquid does not leak out; since the protective cap is made of an elastomer, it will move along with the ring 11 when it deforms under vibration.

[0119] For option B, such as Figure 5 and Figure 6 As shown, the viscoelastic or hysteresis-damping material 20 will deform to dampen vibrations, while the ring 11 provides a certain degree of flexibility as previously described.

[0120] In option C, the thicker spring portion 14b will be vulcanized, wherein the viscoelastic material in the slit 12 will have a similar properties to... Figure 4 The liquid in the slit 12 of the embodiment has the same function.

[0121] Because of the damping effect of the bearing damping element 10 on vibration, resonance problems will be avoided. This will allow the centrifugal compressor 1 to rotate faster and / or have more stages.

[0122] The present invention is not limited to the embodiments described by way of example and shown in the figures, but the multistage centrifugal compressor according to the invention can be implemented in various forms and sizes without departing from the scope of the invention.

Claims

1. A multi-stage centrifugal compressor, comprising a shaft (2) with multiple blades (3) on the shaft, wherein, The shaft (2) is mounted in the housing (4) by means of a bearing (7), characterized in that at least one bearing (7) is provided with a bearing damping element (10), the bearing damping element being composed of a ring (11) arranged between the shaft (2) or the housing (4) and the bearing (7), wherein the ring (11) includes a plurality of slits (12) that pass through the thickness of the ring (11) in the axial direction (X-X') and at a certain distance from the radial inner surface (13a) and the radial outer surface (13b) of the ring (11), wherein the slits (12) at least partially overlap; Among them, at least one of the two axial annular surfaces (16) of the ring (11) is provided with two concentric disks (21), each disk having an axial surface in contact with the axial annular surface of the ring, and the radial inner circumferential surface of the outer disk of the two concentric disks faces the radial outer circumferential surface of the inner disk of the two concentric disks. Among them, the viscoelastic material or hysteresis damping material (20) is sandwiched between the radial inner circumferential surface of the outer disk of the two concentric disks and the radial outer circumferential surface of the inner disk of the two concentric disks and is in contact with both. Among them, the viscoelastic material includes O-rings (23), and the hysteresis damping material includes metal mesh (24).

2. The multi-stage centrifugal compressor according to claim 1, characterized in that, There is no liquid in the slit (12).

3. The multi-stage centrifugal compressor according to claim 2, characterized in that, Both axial annular surfaces (16) of the ring (11) are provided with viscoelastic material or hysteresis damping material.

4. The multi-stage centrifugal compressor according to claim 1, characterized in that, The bearing (7) is a rolling bearing.

5. The multi-stage centrifugal compressor according to claim 1, characterized in that, The bearing (7) at one end of the shaft (2) has a bearing damping element (10).

6. The multi-stage centrifugal compressor according to claim 5, characterized in that, The bearing damping element (10) is located on the non-driven end (9) of the shaft (2).

7. The multi-stage centrifugal compressor according to claim 1, characterized in that, The ring (11) includes at least three slits (12).

8. The multi-stage centrifugal compressor according to claim 1, characterized in that, The slit (12) has a damping part (14a) with a maximum width of 0.5 mm, or a maximum width of 0.2 mm, or a maximum width of 1.15 mm.

9. The multi-stage centrifugal compressor according to claim 1, characterized in that, The slit (12) has a spring portion (14b) with a minimum width of 0.5 mm.

10. The multi-stage centrifugal compressor according to claim 1, characterized in that, There are more than ten blades (3) on the shaft (2).

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