CN112160916A

CN112160916A - Centrifugal compressor with balancing function

Info

Publication number: CN112160916A
Application number: CN202011097379.4A
Authority: CN
Inventors: 王鹏亮; 金鼎铭
Original assignee: Suzhou Eulerturbo Machinery Co ltd
Current assignee: Suzhou Eulerturbo Machinery Co ltd
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2021-01-01

Abstract

The invention relates to a centrifugal compressor with a balance function, which comprises a connecting part and a shell fixed on the connecting part, wherein a compressor rotor coaxially arranged with the shell is arranged in the shell, a plurality of key groups are arranged between the connecting part and the shell along the circumferential direction of the shell, each key group at least comprises one key, and the keys in the key groups can limit the expansion or contraction direction of the shell in the radial direction of the shell and keep the central axis of the shell unchanged during the expansion or contraction process. The central axis of the shell is basically kept unchanged, so that the concentricity of the compressor rotor and the shell is always in a good state under the operating condition, the operating safety of the unit is improved, the uniformity of the gap of the sealing part in the compressor is controlled, and the operating efficiency of the unit is improved.

Description

Centrifugal compressor with balancing function

Technical Field

The invention relates to a centrifugal compressor, in particular to a centrifugal compressor with a balancing function.

Background

The housing (sometimes also called volute) is an essential critical component of a centrifugal compressor, and is mainly used for containing a working medium (gas) of the compressor and sending the working medium out of the compressor according to a certain direction. Compared with rotating parts such as an impeller and a main shaft, the shell is always in a static state in the operation process and belongs to one of stator parts of the compressor. The compressor housing is typically bolted to a compressor base or support bracket, and in some types of compressors, the housing is bolted to a bearing block or gearbox.

Since the centrifugal compressor is generally assembled for the first time in a manufacturing plant, it is generally assembled on site by a user after completing daily maintenance, and the installation temperature thereof is generally ambient temperature, i.e., within the range of-40 ℃ to +40 ℃. However, the operating conditions of the compressor are very different due to different unit parameters, and the temperature of some medium gases is near to hundred degrees centigrade and above hundred degrees centigrade (or low temperature to minus or above hundred degrees centigrade), so that a certain temperature difference inevitably exists between the installation state and the use state. The compressor housing is in direct contact with the gaseous medium, the temperature field of which is directly influenced by the temperature of the working medium. If the expansion direction of the compressor shell is not limited, when the shell is expanded (or contracted) in a thermal state (particularly in some high-temperature and low-temperature units), the expansion of the shell has arbitrariness, so that the center of the shell can be deviated, the concentricity of the rotor component and the shell and the mounting component on the shell can be uncontrollably changed, the sealing component can be eccentric or failed by a light person, and the dynamic and static components can be rubbed by a severe person to cause safety accidents.

It is common practice to design a locating pin or circumferential seam allowance between the housing and the connecting member, but both methods have drawbacks. The initial design of the locating pin is to define the center of the housing by a close fit of the pin with the pin hole. However, for some high-temperature or low-temperature units, the expansion of the shell is inevitable and cannot be completely limited, so that the accident that the positioning pin is cut off after the expansion of the high-temperature unit occurs on site occurs. The seam allowance is arranged in the circumferential direction, contradiction exists between design and practice, and for a high-temperature/low-temperature unit, the expansion difference is large, so that the gap of the seam allowance needs to be large, and the control of the center of the shell is lost. Therefore, the phenomenon that the compressor runs well for the first time, once the compressor is stopped, the center cannot be reset, and the concentricity has large deviation can occur.

Disclosure of Invention

In order to overcome the defects, the invention provides a centrifugal compressor with a balance function, which can limit the expansion direction of a shell, keep the center of the shell basically unchanged, further keep the concentricity of the shell and a compressor rotor in a good state all the time and improve the operation safety of a unit.

The technical scheme adopted by the invention for solving the technical problem is as follows:

a centrifugal compressor with balance function is composed of a connecting part and a casing fixed to said connecting part, a rotor of compressor coaxially arranged with said casing in said casing, several key groups arranged between said connecting part and casing along the circumference of casing, and at least one key in each key group for limiting the expansion or contraction direction of casing in the radial direction of casing and keeping the central axis of casing unchanged.

Preferably, a part of the key is fixed to the housing, the connecting member is provided with a key slot matched with the key, and the other part of the key is inserted into the key slot; or one part of the key is fixed on the connecting part, the shell is provided with a key groove matched with the key, the other part of the key is inserted in the key groove, and the key is fixedly connected on the shell or the connecting part through at least two positioning pins or a screw.

Preferably, the housing is provided with at least three key groups, and the keys in the same key group are in the same circumferential direction of the housing, and each key group is in a different circumferential direction of the housing.

Preferably, the key is a common flat key, the flat key is vertically installed in the housing and the connecting part, the horizontal cross section of the flat key is an oblong structure, the flat key has a first upper surface and a first lower surface which are parallel to each other, and a first front surface and a first rear surface which are parallel to each other, the first upper surface and the first front surface are vertically arranged, when the key is installed, the first upper surface is attached in the housing, the first lower surface is attached in the connecting part, and the first front surface and the first rear surface are both attached in the housing and the connecting part, wherein the first front surface and the first rear surface are two corresponding working surfaces.

Preferably, the key is a special-shaped key, the special-shaped key comprises an upper combining part and a lower combining part which are connected with each other and staggered, a horizontal plane between the upper combining part and the lower combining part is called a combining plane, the horizontal cross sections of the upper combining part and the lower combining part are both in an oval structure, the upper combining part comprises a second upper surface and a combining plane which are parallel to each other, a second front surface and a second rear surface which are parallel to each other, the combining plane is vertically arranged with the second front surface, the lower combining part comprises a combining plane and a second lower surface which are parallel to each other, a third front surface and a third rear surface which are parallel to each other, the combining plane is vertically arranged with the third front surface, when the key is installed, the upper combining part is vertically installed in the shell, the lower combining part is vertically installed in the connecting part, wherein the second front surface and the second rear surface are two opposite working surfaces, the third front surface and the fourth front surface are two opposite working surfaces.

Preferably, a central line parallel to the working face and between two opposite working faces of each key in the same key group is on the same straight line, and an extension line of the straight line intersects with the central axis of the housing and is perpendicular to the central axis, the straight line is called a concentric line, wherein an included angle between the concentric line in any key group and the concentric line in another key group is 90 ° or 180 °, and the included angle of 90 ° and the included angle of 180 ° exist between the concentric lines at the same time.

Preferably, the shell is fixedly connected with the connecting part through a plurality of fasteners, the fasteners are uniformly arranged along the circumferential direction of the shell, and the connecting part is a compressor base, a compressor support frame, a bearing seat or a gear box.

Preferably, the connecting part is a gear box, the gear box comprises a lower box body and an upper box body, the upper box body is fixed above the lower box body through a fastening bolt, and the shell is fixed on one side of the lower box body through a fastening bolt.

Preferably, three key groups including a first key group, a second key group and a third key group are arranged between the housing and the lower case, and the keys in the same key group are in the same circumferential direction of the housing, while the first key group, the second key group and the third key group are in different circumferential directions of the housing.

Preferably, the first key set, the second key set and the third key set are all provided with one key, the keys in the first key set and the second key set are respectively located on a horizontal plane on two sides of the central axis of the housing, the central axis of the housing and the center lines of the keys in the first key set and the second key set in the housing are both located on the horizontal plane, the keys in the third key set are located on a vertical plane perpendicular to the horizontal plane and below the central axis of the housing, and the central axis of the housing and the center lines of the keys in the third key set in the housing are both located on the vertical plane.

The invention has the beneficial effects that: the invention comprises a connecting part and a shell fixed on the connecting part, wherein a plurality of key groups are designed at the connecting part of the shell and the connecting part, keys in each key group are designed side by side, and the extension line of the central point connecting line of each group of keys in the shell is intersected with the central axis of the shell and is mutually vertical, so that when the compressor installed in a normal temperature state runs in a high temperature or low temperature state, the housing can only expand or contract along the radial direction of the housing, so that the central axis of the housing is basically kept unchanged, thereby ensuring that the concentricity of the compressor rotor and the shell is always in a good state under the operating condition, improving the safety of the unit operation, simultaneously, the method is beneficial to controlling the uniformity of the gap of the sealing part in the compressor, improving the operation efficiency of the unit, and the deformation has reversibility, which has very important significance for the safe and efficient operation of the unit.

Drawings

FIG. 1 is a simplified diagram of the present invention;

FIG. 2 is a schematic view of a connecting member in the present invention;

FIG. 3 is a front view of the flat key of the present invention;

FIG. 4 is a left side view of the flat key of the present invention;

FIG. 5 is a top view of a flat key of the present invention;

FIG. 6 is a front view of the key of the present invention;

FIG. 7 is a left side view of the heteromorphic key of the present invention;

FIG. 8 is a top view of the key of the present invention;

in the figure: 10-shell, 11-center axis, 20-connecting part, 21-fastener, 22-keyway, 30-flat key, 31-first upper surface, 32-first lower surface, 33-first front surface, 34-first rear surface, 40-shaped key, 41-upper junction, 42-second upper surface, 43-junction, 44-second front surface, 45-second rear surface, 46-lower junction, 47-third lower surface, 48-third front surface, 49-third rear surface.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Example (b): as shown in fig. 1-2, a centrifugal compressor with a balance function comprises a connecting part 20 and a housing 10 fixed to the connecting part, a compressor rotor is arranged in the housing 10 and is coaxial with the housing, a plurality of key sets are arranged between the connecting part 20 and the housing 10 along the circumferential direction of the housing, each key set comprises at least one key, and the keys in the key sets can limit the expansion or contraction direction of the housing 10 to the radial direction of the housing and keep the central axis 11 of the housing unchanged during the expansion or contraction. The invention improves the traditional centrifugal compressor, and particularly designs a plurality of key groups at the connecting part of a shell 10 and a connecting part 20, the keys in each key group are designed side by side, and the extension lines of the central point connecting lines of each group of keys are intersected with and mutually perpendicular to the central axis of the shell, so that the shell 10 of the compressor installed in a normal temperature state can only expand or contract and displace along the radial direction of the shell when the compressor runs in a high temperature or low temperature state, the central axis 11 of the shell basically keeps unchanged, the concentricity of a rotor and the shell of the compressor is always in a good state under the working condition of running, the running safety of a unit is improved, the control of the uniformity of gaps of sealing parts in the compressor is facilitated, and the running efficiency of the unit is improved.

One part of the key is fixed on the shell 10, the connecting part 20 is provided with a key slot 22 matched with the key, and the other part of the key is inserted and tightly inserted in the key slot; or a part of the key is fixed on the connecting part 20, the housing 10 is provided with a key slot 22 matched with the key, the other part of the key is inserted into the key slot, and the key is fixedly connected on the housing 10 or the connecting part 20 through at least two positioning pins or a screw. In which the key is made of metal material, one part of the key is fixed to the housing 10 or the connection part 20, and the other part is inserted into the key slot 22 of the connection part 20 or the housing 10, so that the key only defines the expansion direction of the housing 10, unlike the positioning pin installed in the conventional art, which is expected to completely limit the expansion of the housing and further define the center of the housing through the close fit of the pin and the pin hole, but for some high-temperature or low-temperature units, the expansion of the housing is inevitable and cannot be completely limited, so that the accident of cutting off the positioning pin occurs. The invention leads the unordered expansion of the shell to be ordered expansion through the arranged keys, namely the shell is expanded only along the radial direction of the shell, but the expansion amount of the shell is not limited, so the invention skillfully ensures that the position of the central axis of the shell is not changed on the basis of releasing the expansion energy of the shell.

At least three key groups are arranged on the shell 10, and the keys in the same key group are in the same circumferential direction of the shell, and each key group is in different circumferential directions of the shell. Further, the keys in the same key set are on the same radius of the housing, and the radius is perpendicular to the central axis of the housing.

As shown in fig. 3 to 5, the key is a general flat key 30, the flat key 30 is vertically installed in the housing 10 and the connecting part 20, a horizontal cross section of the flat key 30 is an oval structure, the flat key 30 has a first upper surface 31 and a first lower surface 32 which are parallel to each other, a first front surface 33 and a first rear surface 34 which are parallel to each other, the first upper surface 31 is vertically arranged with the first front surface 33, when the key is installed, the first upper surface 31 is attached in the housing 10, the first lower surface 32 is attached in the connecting part 20, and the first front surface 33 and the first rear surface 34 are both attached in the housing and the connecting part, wherein the first front surface 33 and the first rear surface 34 are two corresponding working surfaces. Before installation, an operator can preset the key grooves 22 on the shell and the connecting part, and during installation, if the two key grooves 22 are aligned, a common flat key can be selected; as shown in fig. 5, if the distance between the first front surface 33 and the first rear surface 34 is defined as the key width B, the width of the key groove 22 is slightly larger than the key width B, so as to ensure that the key is tightly inserted into the key groove in the width direction, and the width of the key groove 22 is generally 20-50 μm larger than the key width.

As shown in fig. 6-8, the key is a special-shaped key 40, the special-shaped key 40 includes an upper combining portion 41 and a lower combining portion 46 which are connected with each other and are staggered, and a horizontal plane of the mutual combination between the upper combining portion 41 and the lower combining portion 46 is called a combining plane 43, the horizontal cross sections of the upper combining portion 41 and the lower combining portion 46 are both oblong structures, the upper combining portion 41 includes a second upper surface 42 and a combining plane 43 which are parallel to each other, a second front surface 44 and a second rear surface 45 which are parallel to each other, the combining plane 43 is arranged perpendicular to the second front surface 44, the lower combining portion 46 includes a combining plane 43 and a second lower surface 47 which are parallel to each other, a third front surface 48 and a third rear surface 49 which are parallel to each other, the combining plane 43 is arranged perpendicular to the third front surface 48, when being installed, the upper combining portion 41 is vertically installed in the housing 10, the lower combining portion 46 is vertically installed in the connecting member 20, wherein the second front surface 44 and the second rear surface 45 are two opposing working surfaces and the third front surface 48 and the fourth front surface 49 are two opposing working surfaces. If the two key slots 22 are staggered during installation, the special-shaped key 40 is selected, as shown in fig. 7, the distance between the second front surface 44 and the second rear surface 45 is defined as a key width B1, the distance between the third front surface 48 and the third rear surface 49 is defined as a key width B2, B1 and B2 may be the same or different, wherein the distance between the second front surface 44 and the third front surface 48 depends on the staggered distance of the two key slots; the upper combining part 41 and the lower combining part 46 in the special-shaped key are partially overlapped, the structures of the upper combining part 41 and the lower combining part 46 are the same, the central axes are parallel to each other, and the four working surfaces are also parallel to each other, so that the shell is ensured to deform only along the radial direction, the problem of the installation of the compressor is solved skillfully by the arrangement of the special-shaped key 40, and the special-shaped key has practicability.

The central line parallel to the working face and between the two opposite working faces of each key in the same key group is on the same straight line, the extension line of the straight line is intersected with the central axis 11 of the shell and is mutually perpendicular, the straight line is called a concentric line, the included angle between the concentric line in any key group and the concentric line in the other key group is 90 degrees or 180 degrees, and the included angle of 90 degrees and the included angle of 180 degrees exist between the concentric lines at the same time. The plurality of key groups are arranged according to the above mode, so that the shell is further ensured to deform only along the radial direction, and the deformed central axis is kept unchanged, preferably, four key groups are arranged on the shell, two of the key groups are respectively arranged on horizontal planes at the left side and the right side of the central axis of the shell 10, the other two key groups are respectively arranged on vertical planes at the upper side and the lower side of the central axis of the shell 10, two key groups can be designed in the horizontal direction, and one key group is designed in the vertical direction; or one key group is designed in the horizontal direction, and two key groups are designed in the vertical direction, so that the key groups can be conveniently and accurately positioned and installed in actual operation; of course, other angles between the key sets may be used.

The shell 10 and the connecting part 20 are fixedly connected through a plurality of fasteners 21, the plurality of fasteners 21 are uniformly arranged along the circumferential direction of the shell 10, the connecting part 20 is a compressor base, a compressor support frame, a bearing seat or a gear box, and the fasteners 21 are fastening bolts or clamping plates.

In this embodiment, the connection member 20 is a gear box including a lower case and an upper case fixed above the lower case by fastening bolts, and the housing 10 is fixed to one side of the lower case by fastening bolts. Three key groups are arranged between the shell 10 and the lower box body, and comprise a first key group, a second key group and a third key group, keys in the same key group are located in the same circumferential direction of the shell, and the first key group, the second key group and the third key group are located in different circumferential directions of the shell.

The first key group, the second key group and the third key group are all provided with one key, the keys in the first key group and the second key group are respectively positioned on the horizontal planes at two sides of the central axis of the shell, the central axis of the shell and the central lines of the keys in the first key group and the second key group in the shell are positioned in the horizontal plane, the keys in the third key group are arranged on the vertical plane which is mutually perpendicular to the horizontal plane and is positioned below the central axis of the shell, and the central axis of the shell 10 and the central line of the keys in the third key group in the shell are both positioned on the vertical plane. The lower box body of the gear box is provided with three key groups, the first key group and the second key group are arranged on a horizontal plane at the center of the gear box, the third key group is arranged on a vertical plane at the center of the gear box, and the central axis of the gear box is positioned at the intersection of the horizontal plane and the vertical plane.

The practical application of the invention is as follows:

case 1: the centrifugal compressor designed and manufactured by the inventor for certain domestic coal chemical industry enterprises has the working temperature of a medium of about 210 ℃ and the working pressure of about 4.0MP (G), the medium mainly comprises dangerous media such as carbon monoxide, hydrogen and the like, the shell of the compressor is arranged on a gear box, special-shaped keys are arranged between the gear box and the shell, two of the special-shaped keys are arranged in the horizontal direction, one special-shaped key is arranged in the vertical direction, all the special-shaped keys are arranged on the shell, and key grooves are formed in the corresponding parts of the gear box. The unit is assembled in a cold state in an inventor factory, the unit is sent to the site after test run, and in the process of running of the site high-temperature process gas, all parts run well and run stably until now. Due to the lack of the key limited by the expansion direction, the conditions of shell offset and seal eccentric wear after the thermal state operation is stopped often occur to other manufacturers of equipment with the same system, so that great psychological pressure is brought to operators, and the overhaul workload is increased;

case 2: the steam compressor designed and manufactured by the inventor for certain domestic chemical enterprises has the medium working temperature as high as 530 ℃. The unit shell is arranged on a base support plate, and a special-shaped key is arranged between the shell and the support plate. In the starting process of the unit, the worker clearly observes that the shell expands by about 2mm towards the periphery along the key width direction of the special-shaped key in the temperature rising process, and the design of the invention is originally realized.

It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A centrifugal compressor having a balancing function, characterized in that: the compressor rotor comprises a connecting part (20) and a shell (10) fixed on the connecting part, a compressor rotor which is coaxially arranged with the shell is arranged in the shell (10), a plurality of key groups are arranged between the connecting part (20) and the shell (10) along the circumferential direction of the shell, each key group at least comprises one key, the keys in the key groups can limit the expansion or contraction direction of the shell (10) in the radial direction of the shell, and the central axis (11) of the shell is kept unchanged in the expansion or contraction process.

2. The centrifugal compressor with balancing function according to claim 1, characterized in that: one part of the key is fixed on the shell (10), a key groove (22) matched with the key is arranged on the connecting part (20), and the other part of the key is inserted and tightly fixed in the key groove; or one part of the key is fixed on the connecting part (20), a key groove (22) matched with the key is arranged on the shell (10), the other part of the key is inserted and tightly fixed in the key groove, and the key is tightly connected on the shell (10) or the connecting part (20) through at least two positioning pins or a screw.

3. The centrifugal compressor with balancing function according to claim 1, characterized in that: the shell (10) is provided with at least three key groups, keys in the same key group are positioned in the same circumferential direction of the shell, and each key group is positioned in different circumferential directions of the shell.

4. The centrifugal compressor having a balancing function according to claim 3, characterized in that: the key is a common flat key (30), the flat key (30) is vertically installed in a shell (10) and a connecting part (20), the horizontal section of the flat key (30) is of an oval structure, the flat key (30) is provided with a first upper surface (31) and a first lower surface (32) which are parallel to each other, a first front surface (33) and a first rear surface (34) which are parallel to each other, the first upper surface (31) and the first front surface (33) are vertically arranged, when the key is installed, the first upper surface (31) is attached to the inside of the shell (10), the first lower surface (32) is attached to the inside of the connecting part (20), and the first front surface (33) and the first rear surface (34) are both attached to the shell and the connecting part, wherein the first front surface (33) and the first rear surface (34) are two corresponding working surfaces.

5. The centrifugal compressor having a balancing function according to claim 3, characterized in that: the key is a special-shaped key (40), the special-shaped key (40) comprises an upper combining part (41) and a lower combining part (46) which are connected with each other and staggered, the horizontal plane of the mutual combination between the upper combining part (41) and the lower combining part (46) is called a combining plane (43), the horizontal cross sections of the upper combining part (41) and the lower combining part (46) are both in an oval structure, the upper combining part (41) comprises a second upper surface (42) and a combining plane (43) which are parallel to each other, a second front surface (44) and a second rear surface (45) which are parallel to each other, the combining plane (43) and the second front surface (44) are vertically arranged, the lower combining part (46) comprises a combining plane (43) and a second lower surface (47) which are parallel to each other, a third front surface (48) and a third rear surface (49) which are parallel to each other, and the combining plane (43) and the third front surface (48) are vertically arranged, when the connecting component is installed, the upper combining part (41) is vertically installed in the shell (10), the lower combining part (46) is vertically installed in the connecting component (20), the second front surface (44) and the second rear surface (45) are two opposite working surfaces, and the third front surface (48) and the fourth front surface (49) are two opposite working surfaces.

6. The centrifugal compressor with a balancing function according to claim 4 or 5, characterized in that: the central line parallel to the working face and between the two opposite working faces of each key in the same key group is on the same straight line, the extension line of the straight line is intersected with the central axis (11) of the shell and is mutually perpendicular, the straight line is called a concentric line, the included angle between the concentric line in any key group and the concentric line in the other key group is 90 degrees or 180 degrees, and the included angle of 90 degrees and the included angle of 180 degrees exist between the concentric lines at the same time.

7. The centrifugal compressor having a balancing function according to claim 3, characterized in that: the shell (10) is fixedly connected with the connecting part (20) through a plurality of fasteners (21), the fasteners (21) are uniformly arranged along the circumferential direction of the shell (10), and the connecting part (20) is a compressor base, a compressor support frame, a bearing seat or a gear box.

8. The centrifugal compressor with a balancing function according to claim 7, characterized in that: the connecting component (20) is a gear box, the gear box comprises a lower box body and an upper box body, the upper box body is fixed above the lower box body through fastening bolts, and the shell (10) is fixed on one side of the lower box body through the fastening bolts.

9. The centrifugal compressor with a balancing function according to claim 8, characterized in that: three key groups are arranged between the shell (10) and the lower box body, and comprise a first key group, a second key group and a third key group, keys in the same key group are located in the same circumferential direction of the shell, and the first key group, the second key group and the third key group are located in different circumferential directions of the shell.

10. The centrifugal compressor with balancing function according to claim 9, characterized in that: the first key group, the second key group and the third key group are provided with one key, the keys in the first key group and the second key group are respectively positioned on the horizontal planes at two sides of the central axis of the shell, the central axis of the shell and the central lines of the keys in the first key group and the second key group in the shell are positioned in the horizontal plane, the keys in the third key group are arranged on the vertical plane which is mutually perpendicular to the horizontal plane and is positioned below the central axis of the shell, and the central axis of the shell (10) and the central line of the keys in the third key group in the shell are both positioned on the vertical plane.