A centrifugal compressor seal arrangement

Abstract

The utility model discloses a centrifugal compressor sealing structure, including leakage inlet, first leakage outlet and second leakage outlet, the leakage inlet is located blade edge department of the impeller, the back side of the impeller is equipped with the sealing cavity, both sides of the sealing cavity are equipped with first sealing tooth and second sealing tooth, the first sealing tooth is located the side of sealing cavity close to the leakage inlet, and the back gap cooperation with the impeller forms the first stage leakage path of leakage inlet to sealing cavity, the second sealing tooth is located the side of sealing cavity away from the leakage inlet, and the wheel cover fixed connection is formed to the second stage leakage path of sealing cavity to first, second leakage outlet. The utility model has solved the leakage problem of the assembly gap in the rotating fluid machinery, has reduced the leakage of fluid, and has improved the leakproofness.

Description

Technical Field

[0001] This utility model belongs to the technical field of compressor equipment, and in particular, relates to a sealing structure for a centrifugal compressor. Background Technology

[0002] A centrifugal compressor is a compressor that uses an impeller to do work on gas, causing the gas to flow radially through the impeller under increased pressure and velocity, ultimately completing the gas transport. During operation, gas enters the compressor and is drawn into the compressor impeller inlet. The high-speed rotation of the impeller compresses the gas from its normal pressure state to high pressure and delivers it to the compressor outlet. Because the impeller is a rotating component, a certain gap will be generated during its assembly and mating with other stationary components of the compressor. After being compressed by the impeller, the gas becomes high-pressure gas. Due to the high pressure state of the compressed gas, it will flow into the low-pressure area along the gap between the impeller shaft and the impeller back, causing leakage. This will affect the supply of compressed gas and the outlet pressure, adversely affecting the overall operating efficiency and reliability of the machine. Furthermore, some units use inert gases or other gases as the working medium, allowing only internal gas leakage within the unit; external leakage must be strictly controlled.

[0003] To reduce compressor gas leakage, existing methods involve adding sealing teeth at gap locations, such as on the rotating impeller disc. These teeth are arranged sequentially, creating a series of throttling gaps and expansion cavities within each tooth, forming a labyrinthine sealing structure. High-pressure gas leaking from the impeller outlet flows out through this sealing structure, generating a throttling effect to reduce gas leakage. Generally, a higher number of sealing teeth is considered to result in a better seal. However, manufacturing these teeth is costly and increases structural complexity, affecting the structural strength of the impeller and sealing device. Adding sealing teeth to the impeller back also affects the pressure distribution on that side, thus influencing the axial thrust. Some compressors use carbon seals to prevent external leakage, but carbon seals wear down during use, requiring periodic inspection and maintenance, leading to system complexity and higher costs.

[0004] Existing patent publication number CN110056513A discloses a sealing structure for a steam centrifugal compressor, including a compressor housing, a compressor impeller, a gearbox, a gearbox connecting plate, a connecting flange, an impeller back plate, an impeller tie rod, a lubricating oil vapor sealing plate, a sealing seat, a sealing disc, and a gearbox oil seal. The connecting flange is sealed and fixedly connected to the impeller back plate and the compressor housing. The gearbox connecting plate is sealed and fixedly connected between the housing and the connecting flange. The sealing disc and the sealing seat cooperate to form a radial annular sealing channel one, the sealing disc and the lubricating oil vapor sealing plate cooperate to form an axial annular sealing channel two, the lubricating oil vapor sealing plate and the gearbox shaft cooperate to form a sealing channel three, and the gearbox oil seal and the gearbox main shaft cooperate to form a sealing channel four. However, this patent structure is relatively complex, with too many parts, resulting in high maintenance costs.

[0005] Existing patent publication number CN215486780U discloses a novel compressor sealing structure, including a first air seal channel formed by the radial fit between the impeller back and the partition plate; and a second air seal channel formed by the axial fit between the main shaft and the partition plate. The first air seal channel contains a radial air seal structure, and the second air seal channel contains an axial air seal structure. The purpose of this invention is to solve the problem of large impeller leakage in existing shaft end sealing structures. During compressor operation, the high-pressure airflow at the impeller outlet leaks through the air seal channel between the impeller back and the partition plate. With the sealing structure of this invention, the pressure of the high-pressure airflow at the impeller outlet gradually decreases after passing through the radial and axial air seal structures. While this patent controls gas leakage through different comb teeth and raised cross-sections, the gradual pressure reduction method still results in gas leakage. Utility Model Content

[0006] This invention primarily addresses the issue of existing compressors where gaps occur, such as those on the rotating impeller disc. Sealing teeth are added sequentially, creating a series of throttling gaps and expansion cavities within each tooth, forming a labyrinthine sealing structure. High-pressure gas leaking from the impeller outlet flows out through this sealing structure, generating a throttling effect to reduce gas leakage. However, manufacturing the sealing teeth is costly and increases structural complexity, affecting the structural strength of the impeller and sealing device. Some compressors use carbon seals to prevent external leakage, but carbon seals experience wear during use, requiring periodic inspection and maintenance, resulting in system complexity and higher costs. Therefore, this invention proposes a centrifugal compressor sealing structure.

[0007] A centrifugal compressor sealing structure includes a wheel cover, a volute, an impeller, and a motor. The volute is fitted around the outside of the impeller, and the impeller is driven by the motor. The structure also includes a leakage inlet, a first leakage outlet, and a second leakage outlet. The leakage inlet is located at the edge of the impeller blades. A sealing cavity is provided on the back side of the impeller, and a first sealing tooth and a second sealing tooth are provided on both sides of the sealing cavity. The first sealing tooth is located on the side of the sealing cavity closer to the impeller inlet and is clearance-fitted with the back of the impeller, forming a first-stage leakage path from the leakage inlet to the sealing cavity. The second sealing tooth is located on the side of the sealing cavity away from the impeller inlet and is fixedly connected to the wheel cover, forming a second-stage leakage path from the sealing cavity to the first and second leakage outlets. A regulating valve is provided at the first leakage outlet to regulate the gas flow rate at the first leakage outlet.

[0008] Furthermore, the first sealing tooth and the second sealing tooth are arranged axially along the back side of the impeller, with the first sealing tooth located away from the axis of the impeller and the second sealing tooth located close to the axis of the impeller.

[0009] Furthermore, both the first sealing tooth and the second sealing tooth have a comb-shaped structure, and the first sealing tooth is positioned higher than the second sealing tooth.

[0010] Furthermore, a pressure sensor is installed inside the sealed cavity to detect the pressure inside the sealed cavity.

[0011] Furthermore, the leakage inlet is located near the mating point between the volute and the impeller, and the leakage inlet is connected to the area inside the compressor where a leak occurs via a pipe or channel, for collecting the leaked gas.

[0012] Furthermore, it also includes an air intake channel and an impeller inlet. One end of the air intake channel is connected to the sealing cavity through a second leakage outlet, and the other end passes through the impeller cover and is connected to the impeller inlet.

[0013] Furthermore, the sealing cavity is an annular cavity formed between the impeller back and the stationary part of the compressor, arranged circumferentially around the impeller main shaft, and the annular cavity is the part separated by the first sealing tooth and the second sealing tooth.

[0014] Furthermore, the positions of both the first sealing tooth and the first leakage outlet are adjustable.

[0015] Furthermore, the second leakage outlet is located at the bottom of the side of the second sealing tooth away from the sealing cavity, and the outlet end of the second leakage outlet is lower than the lowest position of the sealing cavity, for discharging leaked gas.

[0016] Furthermore, the impeller has multiple holes on its back for venting leaked gas.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0018] 1. This utility model includes a wheel cover, a volute, an impeller, and a motor. The volute is sleeved on the outside of the impeller, and the impeller is connected to the motor for transmission. It also includes a leakage inlet, a first leakage outlet, and a second leakage outlet. The leakage inlet is located at the edge of the impeller blades. This utility model, through pressure reduction by two sealing teeth and structural optimization, guides the gas leaking from the impeller outlet (the gap between the rotating and stationary parts) to the impeller inlet (internal leakage). By optimizing the sealing teeth and the wheel back structure, the amount of gas leakage is reduced, solving the problem of leakage caused by assembly gaps in rotating fluid machinery, improving the sealing effect, and making the centrifugal compressor almost leak-free during operation.

[0019] 2. This utility model has a simple structure, without the need for complex structures, which improves the stability and operating efficiency of the system, thereby saving power consumption and cost, and improving the overall operating performance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model;

[0021] Figure 2 This is a schematic diagram of the airflow and sealing on the back of the impeller of this utility model.

[0022] Figure 3 This is a schematic diagram of the structure of Embodiment 3 of this utility model;

[0023] Figure 4 This is a schematic diagram of the airflow and sealing on the back of the impeller in Embodiment 3 of this utility model.

[0024] In the above figure, 1. wheel cover; 2. volute; 3. impeller; 4. impeller inlet; 5. motor; 6. first sealing tooth; 7. sealing cavity; 8. second sealing tooth; 9. leakage inlet; 10. first leakage outlet; 11. second leakage outlet; 12. air duct. Detailed Implementation

[0025] To clearly illustrate the technical features of this utility model, the following detailed description is provided through specific embodiments and in conjunction with the accompanying drawings.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0027] Furthermore, in the description of this utility model, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] In this utility model, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0030] Example 1

[0031] like Figure 1 and Figure 2As shown, a centrifugal compressor sealing structure includes a wheel cover 1, a volute 2, an impeller 3, and a motor 5. The volute 2 is sleeved on the outside of the impeller 3, and the impeller 3 is drivenly connected to the motor 5. The structure also includes a leakage inlet 9, a first leakage outlet 10, and a second leakage outlet 11. The leakage inlet 9 is located at the edge of the blades of the impeller 3. A sealing cavity 7 is provided on the back side of the impeller 3, and a first sealing tooth 6 and a second sealing tooth 8 are provided on both sides of the sealing cavity 7. The first sealing tooth 6 is located on the side of the sealing cavity 7 near the leakage inlet 9 and is clearance-fitted with the back side of the impeller 3, forming a first-stage leakage path from the leakage inlet 9 to the sealing cavity 7. The second sealing tooth 8 is located on the side of the sealing cavity 7 away from the leakage inlet 9 and is fixedly connected to the wheel cover 1, forming a second-stage leakage path from the sealing cavity 7 to the first and second leakage outlets.

[0032] In this embodiment, the volute 2 is disposed on the outer side of the impeller 3 blades to collect the compressed high-pressure gas. The leakage inlet 9 is located at the edge of the impeller 3 blades to capture leaked gas in a timely manner. Specifically, the leakage inlet 9 is located near the mating point between the volute 2 and the impeller 3. The leakage inlet 9 is connected to the area inside the compressor where a leak occurs via a pipe or channel to collect the leaked gas. A sealing cavity 7 is provided on the back side of the impeller 3. This sealing cavity 7 is an annular cavity arranged circumferentially around the main shaft of the impeller 3. On the side of the sealing cavity 7 near the impeller inlet 4, a first sealing tooth 6 is installed. The first sealing tooth 6 is in clearance fit with the back of the impeller 3, forming a first-stage leakage path from the leakage inlet 9 to the sealing cavity 7. On the side of the sealing cavity 7 away from the leakage inlet 9, a second sealing tooth 8 is fixedly connected to the impeller cover 1, constructing a second-stage leakage path from the sealing cavity 7 to the first and second leakage outlets. The second leakage outlet 11 is located at the bottom of the side of the second sealing tooth 8 away from the sealing cavity 7. The outlet end is lower than the lowest position of the sealing cavity 7 to ensure that the gas can be discharged smoothly.

[0033] In this embodiment, when the centrifugal compressor is running, the gas entering through the impeller inlet 4 enters the impeller 3 and is compressed into high-pressure gas by the rotation of the impeller 3. Most of the gas enters the volute 2 and is then discharged. Due to the gap between the impeller 3 and the stationary parts, a small portion of the gas flows out along the gap of the impeller 3 and enters the leakage inlet 9. The gas entering from the leakage inlet 9 passes through the first sealing tooth 6. When the gas passes through the first sealing tooth 6, it undergoes multiple throttling and expansion, and its kinetic energy is converted into heat energy, thereby significantly reducing the leakage and playing a role in interception and pressure reduction. After the interception and pressure reduction effect of the first sealing tooth 6, the leakage of the gas flowing into the leakage inlet 9 has been reduced. This part of the gas enters the sealing cavity 7, and most of the gas enters the first leakage outlet 10. If a very small portion of the gas enters the second leakage outlet 11 through the sealing cavity 7, the second sealing tooth 8 located at the second leakage outlet 11 plays a role in interception and pressure reduction, which can further reduce the gas leakage.

[0034] Example 2

[0035] like Figure 1 and Figure 2 As shown, a centrifugal compressor sealing structure includes a wheel cover 1, a volute 2, an impeller 3, and a motor 5. The volute 2 is sleeved on the outside of the impeller 3, and the impeller 3 is drivenly connected to the motor 5. The structure also includes a leakage inlet 9, a first leakage outlet 10, and a second leakage outlet 11. The leakage inlet 9 is located at the edge of the blades of the impeller 3. A sealing cavity 7 is provided on the back side of the impeller 3, and a first sealing tooth 6 and a second sealing tooth 8 are provided on both sides of the sealing cavity 7. The first sealing tooth 6 is located on the side of the sealing cavity 7 near the leakage inlet 9 and is clearance-fitted with the back side of the impeller 3, forming a first-stage leakage path from the leakage inlet 9 to the sealing cavity 7. The second sealing tooth 8 is located on the side of the sealing cavity 7 away from the leakage inlet 9 and is fixedly connected to the wheel cover 1, forming a second-stage leakage path from the sealing cavity 7 to the first and second leakage outlets.

[0036] In this embodiment, the first sealing tooth 6 and the second sealing tooth 8 are arranged axially along the back side of the impeller 3. The first sealing tooth 6 is away from the axis of the impeller 3, and the second sealing tooth 8 is close to the axis of the impeller 3. The first sealing tooth 6 is set higher than the second sealing tooth 8. Both are comb-shaped structures, which effectively enhance the sealing effect. At the same time, several small holes are opened on the back of the impeller 3. These small holes are connected to the motor base, so that the gas leaking from the gap flows back to the impeller inlet 4. When the compressor is running, some gas leaks from the gap at the outlet of the impeller 3. After passing through the first sealing tooth 6, the gas pressure decreases and the gas volume decreases. Then the gas enters the small hole and the sealing cavity 7. Most of the gas enters the small hole and passes through the impeller 3, and then flows back to the impeller inlet 4. A very small amount of gas flows to the axial position through the sealing cavity 7. Through the pressure reduction and leakage prevention effect of the second sealing tooth 8, the effect of almost no gas leakage is achieved. The differential pressure stage leakage control formed by the high and low double comb teeth, combined with the low exhaust port design, effectively blocks the gas leakage to the motor 5 side.

[0037] Example 3

[0038] like Figure 3 and Figure 4 As shown, in this embodiment, an air intake channel 12 is also provided. One end of the air intake channel 12 is connected to the sealing cavity 7 through the first leakage outlet 10, and the other end passes through the impeller cover 1 and is connected to the impeller inlet 4, so that the gas can circulate in the sealing cavity 7, reducing gas accumulation and improving the operating stability of the compressor. The second leakage outlet 11 is connected to the atmosphere, and the pressure at its location is atmospheric pressure. The tip of the first sealing tooth 6 has an asymmetrical inclined structure, with its inclined surface tilted towards the leakage inlet 9, and the side facing away from the sealing cavity 7 is a vertical wall surface. The tip of the second sealing tooth 8 is provided with multi-stage stepped grooves, and the opening direction of the grooves is opposite to the leakage flow direction, which is used to generate turbulence and pressure reduction in the second stage leakage path.

[0039] In this embodiment, the sealing gap and outlet position can be dynamically adjusted by adjusting the position of the first sealing tooth 6 and the first leakage outlet 10, as well as the size of the first leakage outlet 10. Adjusting the position and size of the sealing tooth and leakage outlet adapts to different operating conditions, ensuring optimal sealing performance. As shown in Table 1, taking a certain model of centrifugal compressor as an example, the radial hole position 75 / tooth 80 respectively indicates that the distance from the first leakage outlet 10 to the shaft center is 75mm and the distance from the first sealing tooth 6 to the shaft center is 80mm.

[0040] Table 1

[0041] Radial hole position 75 / tooth 80 0.0883％ No radial hole / tooth 80 1.5368％ Radial hole position 55 / tooth 80 0.0618％ Radial hole position 65 / tooth 80 0.0696％ Radial hole position 75 / tooth 80 0.0883％ Radial hole position 75 / tooth 80 0.0883％ Radial hole position 75 / tooth 90 0.0940％ Radial hole position 75 / tooth 100 0.1149％ Radial hole position 75 / tooth 80 0.0883％ Radial hole position 85 / tooth 90 0.1029％ Radial hole position 95 / tooth 100 0.1208％ Radial hole area 360 / tooth 80 0.1352％ Radial hole area size 452 / tooth 80 0.0883％ Radial hole area size 720 / tooth 80 0

[0042] The radial hole represents the first leakage outlet 10, and the tooth represents the first sealing tooth 6. Without the radial hole, the leakage rate is 1.5368%; while with the radial hole, the leakage rate is only 0.0883%. When adjusting the radial hole position, the closer the radial hole is to the shaft center, the lower the leakage rate; when the radial hole position remains unchanged and the tooth position is adjusted away from the shaft center, the leakage rate increases; when both the radial hole and tooth positions are away from the shaft center, the leakage rate increases. Similarly, increasing the size of the first leakage outlet 10 allows most of the gas to flow out from the first leakage outlet 10, enter the bleed air channel 12, and then enter the impeller inlet 4, completing gas recirculation and thus preventing external leakage. The leakage rate of the hole with the largest area in Table 1 is zero.

[0043] Obviously, the above-described embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A centrifugal compressor sealing structure, comprising a wheel cover, a volute, an impeller, and a motor, wherein the volute is sleeved on the outside of the impeller, and the impeller is drivenly connected to the motor, characterized in that, It also includes a leakage inlet, a first leakage outlet, and a second leakage outlet. The leakage inlet is located at the edge of the impeller blades. A sealing cavity is provided on the back side of the impeller. A first sealing tooth and a second sealing tooth are provided on both sides of the sealing cavity. The first sealing tooth is located on the side of the sealing cavity closer to the leakage inlet and is in clearance fit with the back of the impeller to form a first-stage leakage path from the leakage inlet to the sealing cavity. The second sealing tooth is located on the side of the sealing cavity away from the leakage inlet and is fixedly connected to the impeller cover to form a second-stage leakage path from the sealing cavity to the first and second leakage outlets. A regulating valve is provided at the first leakage outlet to regulate the gas flow rate at the first leakage outlet.

2. The centrifugal compressor sealing structure according to claim 1, characterized in that, The first sealing tooth and the second sealing tooth are arranged axially along the back side of the impeller, with the first sealing tooth located away from the axis of the impeller and the second sealing tooth located close to the axis of the impeller.

3. The centrifugal compressor sealing structure according to claim 2, characterized in that, Both the first sealing tooth and the second sealing tooth have a comb-shaped structure, and the first sealing tooth is positioned higher than the second sealing tooth.

4. The centrifugal compressor sealing structure according to claim 1, characterized in that, A pressure sensor is installed inside the sealed cavity to detect the pressure inside the sealed cavity.

5. A centrifugal compressor sealing structure according to claim 1, characterized in that, The leakage inlet is located near the junction of the volute and the impeller. The leakage inlet is connected to the area inside the compressor where the leakage occurs via a pipe or channel, and is used to collect the leaked gas.

6. A centrifugal compressor sealing structure according to claim 1, characterized in that, It also includes an air intake channel and an impeller inlet. One end of the air intake channel is connected to the sealing cavity through a second leakage outlet, and the other end passes through the impeller cover and is connected to the impeller inlet.

7. A centrifugal compressor sealing structure according to claim 1, characterized in that, The sealing cavity is an annular cavity formed between the impeller back and the stationary part of the compressor, arranged circumferentially around the impeller main shaft, and the annular cavity is the part separated by the first sealing tooth and the second sealing tooth.

8. A centrifugal compressor sealing structure according to claim 1, characterized in that, The positions of the first sealing tooth and the first leakage outlet are both adjustable.

9. A centrifugal compressor sealing structure according to claim 1, characterized in that, The second leakage outlet is located at the bottom of the second sealing tooth on the side away from the sealing cavity, and the outlet end of the second leakage outlet is lower than the lowest position of the sealing cavity, for discharging leaked gas.

10. A centrifugal compressor sealing structure according to claim 1, characterized in that, The impeller has multiple holes on its back for venting leaked gas.

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