Balance air pipe connecting structure of centrifugal compressor

Abstract

The utility model provides a centrifugal compressor balance air pipe connecting structure which comprises a machine shell, an end cover and a balance air pipe, one end of the balance air pipe is connected with a first balance air opening flange, a first balance air opening is formed in the machine shell and communicated into a compressor inlet, and the other end of the balance air pipe is connected with a connecting through hole flange. The connecting through hole is radially arranged on the casing, extends into the end cover connected with the casing and is communicated with one end of the second balance gas opening hole in the end cover, and the other end of the second balance gas opening hole is communicated into the casing balance disc rear cavity. According to the balance air pipe connecting structure of the centrifugal compressor, the air leakage risk of the compressor can be reduced, installation is convenient, and meanwhile the problem that in the prior art, the balance air pipe is difficult to arrange can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to technical field, especially relate to a centrifugal compressor balance gas pipe connecting structure. BACKGROUND

[0002] In order to make the rotor axial thrust value of centrifugal compressor be in the thrust bearing carrying range, a balance disc is designed at the high pressure end of compressor rotor, and the balance cavity behind the balance disc is communicated with the compressor inlet through the balance gas pipe. The gas medium leaked into the balance cavity through the sealing of the balance disc is quickly returned to the compressor inlet through the balance gas pipe, so that the pressure in the balance cavity is close to the pressure of the compressor inlet, that is, a low pressure cavity is formed in the balance cavity. The front of the balance disc is the high pressure side, and the pressure value is about the static pressure of the outlet of the last stage impeller. The pressure difference before and after the balance disc provides a force opposite to the total axial thrust of the impeller, thereby offsetting part of the axial force of the rotor, achieving the effect of adjusting the total residual axial force of the rotor.

[0003] If the gas leaked into the balance cavity of the balance disc cannot be returned to the compressor inlet in time, the pressure in the balance cavity will rise, the pressure difference before and after the balance disc will decrease, the effect of the balance disc on offsetting the axial thrust will be weakened, the rotor axial thrust will rise, and problems such as the temperature rise of the thrust bearing tile and the increase of the rotor shaft displacement will be caused, thereby affecting the normal operation of the unit.

[0004] In order to avoid the above problems, the diameter DN and the number of the balance gas pipe are usually increased to reduce the gas flow rate in the balance gas pipe and the pressure rise of the gas in the balance cavity compared with the compressor inlet. Referring to Figure 3 and Figure 4 , they are respectively the sectional view and the left view of the balance gas pipe connecting structure in the prior art, and in the drawings, 1 is a casing, 2 is an end cover, and 3 is a balance gas pipe. The balance gas pipe 3 has two ends of the flange, which is connected with the balance gas flange on the casing 1 and the end cover 2. Among them, the flange nominal diameter DN of the flange A of the balance gas pipe 3 is limited by the sizes D1 and D2 of the components adjacent to the flange A, such as the fixed clasp ring on the outside of the casing 1 and the oil return side cover on the inside of the casing 1, and the number of these components adjacent to the flange A is relatively large, so it is difficult to install the flange A of the balance gas pipe 3 on the annular end surface between these components adjacent to the flange A, thereby limiting the increase of the flange nominal diameter DN of the flange A of the balance gas pipe 3 and the increase of the number of the balance gas pipe 3.

[0005] Therefore, in order to increase the diameter DN and the number of the balance gas pipe 3, the value of the outer diameter D3 of the casing 1 is usually increased in the design to solve the above arrangement problem of the balance gas pipe 3, but this will increase the outer diameter size and the weight of the unit, making the unit become bulky. Not only the machining and manufacturing difficulty is increased, the material and processing cost is wasted, but also the difficulty and cost of transportation, on-site installation and maintenance are increased, and the project construction cost of civil foundation and auxiliary equipment is also increased.

[0006] Therefore, there is an urgent need for a new centrifugal compressor balance pipe connection structure to solve the problem of difficult arrangement of the balance pipe in the prior art. Content of the utility model

[0007] The utility model solves the technical problem of providing a centrifugal compressor balance pipe connection structure which can reduce the risk of gas leakage and is easy to install, and can solve the problem of difficult arrangement of the balance pipe in the prior art.

[0008] To solve the above technical problems, the utility model provides a centrifugal compressor balance pipe connection structure, which comprises a shell, an end cover and a balance pipe, one end of the balance pipe is connected with a first balance gas opening flange, the first balance gas opening is arranged on the shell and is communicated to the compressor inlet, the other end of the balance pipe is connected with a connecting through hole flange, the connecting through hole is radially arranged on the shell and extends into the end cover connected with the shell and is communicated with one end of a second balance gas opening in the end cover, the other end of the second balance gas opening is communicated to the balance cavity behind the balance disc of the shell.

[0009] Further, one section of the connecting through hole in the shell is a through hole with a counterbore, and one section of the connecting through hole in the end cover is a tapered internal thread hole.

[0010] Further, a cap connection joint matched with the connecting through hole is arranged in the connecting through hole, and an external thread is arranged at the end of the connection joint, the connection joint is arranged in the connecting through hole and is screwed with the tapered internal thread hole in the end cover.

[0011] Further, the outside of the cap part of the connection joint and the inside of the counterbore of the connecting through hole are respectively provided with first annular sealing grooves, and O-shaped sealing rings matched with the first annular sealing grooves are arranged in the first annular sealing grooves.

[0012] Further, flanges are arranged at both ends of the balance pipe, threaded blind holes matched with the connecting holes on the flanges at the ends of the balance pipe are arranged on the outer walls of the shell around the first balance gas opening and the connecting through hole, and the balance pipe is fixedly connected with the outer walls of the shell by connecting bolts through the connecting holes on the flanges at the ends of the balance pipe and the threaded blind holes on the outer walls of the shell.

[0013] Further, the inner side surfaces of the flanges at the ends of the balance pipe and the outer walls of the shell are respectively provided with second annular sealing grooves, and metal annular gaskets matched with the second annular sealing grooves are arranged in the second annular sealing grooves.

[0014] Further, the flanges at the ends of the balance pipe are non-standard flanges.

[0015] The utility model provides a centrifugal compressor balance gas pipe connecting structure, both ends of balance gas pipe are connected with the outer wall flange of casing, because the arrangement space of outer wall of casing is less limited, thus avoid the flange nominal diameter DN and the number of balance gas pipe flange to be limited and interfered by the size of fixed snap ring on end cover and oil return side cover on the inner side of casing and other adjacent flange components when one end of balance gas pipe is connected with the end cover of centrifugal compressor, thereby the drift diameter DN of balance gas pipe and the number of balance gas pipe can be designed according to actual needs, and further the problem that the gas leaked from balance disc to balance cavity cannot return to the inlet of compressor in time can be solved effectively.

[0016] And, the utility model provides a centrifugal compressor balance gas pipe connecting structure, both ends of balance gas pipe are connected with the outer wall flange of casing, because the arrangement space of outer wall of casing is less limited, thus avoid the flange nominal diameter DN and the number of balance gas pipe flange to be limited and interfered by the size of fixed snap ring on end cover and oil return side cover on the inner side of casing and other adjacent flange components when one end of balance gas pipe is connected with the end cover of centrifugal compressor, thereby the drift diameter DN of balance gas pipe and the number of balance gas pipe can be designed according to actual needs, and further the problem that the gas leaked from balance disc to balance cavity cannot return to the inlet of compressor in time can be solved effectively. ACCURACY OF DRAWINGS

[0017] Figure 1 It is a centrifugal compressor balance gas pipe connecting structure's schematic diagram provided for the utility model embodiment;

[0018] Figure 2 It is the enlarged view of connecting joint and connecting through hole connection in the centrifugal compressor balance gas pipe connecting structure provided for the utility model embodiment;

[0019] Figure 3 It is the centrifugal compressor balance gas pipe connecting structure sectional view in prior art provided for the utility model;

[0020] Figure 4 It is the centrifugal compressor balance gas pipe connecting structure B side view in prior art provided for the utility model. SPECIFIC EMBODIMENTS

[0021] Reference Figure 1 The utility model embodiment provides a centrifugal compressor balance gas pipe connecting structure, including casing 1, end cover 2 and balance gas pipe 3.

[0022] Among them, balance gas pipe 3 one end is connected with first balance gas opening 7 flange, first balance gas opening 7 is set up on casing 1 and is communicated to compressor inlet inside. The other end of balance gas pipe 3 is connected with the flange of connecting through hole 4, and the connecting through hole 4 is radially arranged on the casing 1 and extends into the end cover 2 connected with the casing 1 and is communicated with one end of the second balance gas opening 8 in the end cover 2, and the other end of the second balance gas opening 8 is communicated into the balance cavity behind the balance disc of the casing 1, so that the balance gas pipe 3 can connect the balance cavity behind the balance disc at the high pressure end of the compressor rotor with the compressor inlet.

[0023] When the gas medium leaks from the sealing position of the balance disc into the balance chamber behind the balance disc, the gas medium will quickly flow back from the second balance gas opening 8 to the connecting through hole 4, then flow to the first balance gas opening 7 through the balance gas pipe 3 via the connecting through hole 4, and then flow into the compressor inlet from the first balance gas opening 7, so that the pressure in the balance chamber can be close to the pressure of the compressor inlet. Since the front of the balance disc is the high-pressure side, the pressure value is about the static pressure at the outlet of the last-stage impeller, so that the pressure difference between the front and back of the balance disc will generate a force opposite to the total axial thrust of the impeller on the rotor, thereby offsetting part of the axial force of the rotor, achieving the effect of adjusting the total residual axial force of the rotor.

[0024] The connecting through hole 4 is a through hole with a counterbore in the casing 1, and the connecting through hole 4 is a tapered internal thread hole in the end cover 2.

[0025] Referring to Figure 2 Since the connecting through hole 4 is radially arranged at the connection between the casing 1 and the end cover 2, in order to ensure the gas tightness of the connection between the connecting through hole 4 and the balance gas pipe 3 and the balance chamber, a cap-equipped connecting joint 5 matched with the connecting through hole 4 is arranged in the connecting through hole 4, so that the gas medium in the balance chamber can directly enter the connecting joint 5 from the second balance gas opening 8, and then enter the compressor inlet from the connecting joint 5 in sequence through the balance gas pipe 3 and the first balance gas opening 7, avoiding the leakage of the gas medium from the gap between the casing 1 and the end cover 2 when the gas medium directly passes through the connecting through hole 4. Not only the gas tightness of the centrifugal compressor is ensured, but also the both ends of the balance gas pipe 3 are connected with the outer wall of the casing, which also solves the problem of difficult arrangement of the balance gas pipe 3 in the prior art.

[0026] In addition, in order to facilitate the connection of the connecting joint 5 and the connecting through hole 4, and also to further ensure the gas tightness of the connection between the connecting joint 5 and the connecting through hole 4, an external thread is arranged at the end of the connecting joint 5, and the connecting joint 5 is arranged in the connecting through hole 4 and is threadedly connected with the tapered internal thread hole in the end cover 2.

[0027] As a specific embodiment of the utility model, in order to further ensure the gas tightness of the connection between the connecting joint 5 and the connecting through hole 4, a first annular sealing groove is arranged on the outside of the cap-equipped part of the connecting joint 5 and the inside of the counterbore of the connecting through hole 4, respectively, and an O-shaped sealing ring 6 matched with the first annular sealing groove is arranged in the first annular sealing groove.

[0028] In order to facilitate the connection of the balance pipe 3 and the shell 1, flanges are arranged at both ends of the balance pipe 3, and threaded blind holes matched with the connecting holes on the end flanges of the balance pipe 3 are arranged on the outer wall of the shell 1 around the first balance gas opening 7 and the connecting through hole 4, and the balance pipe 3 is fixedly connected with the outer wall of the shell 1 by the connecting bolts through the connecting holes on the end flanges and the threaded blind holes on the outer wall of the shell 1.

[0029] As a specific embodiment of the utility model, in order to further ensure the air tightness of the connection between the balance pipe 3 and the outer wall of the shell 1, second annular sealing grooves are arranged on the inner side of the flanges at the ends of the balance pipe 3 and the outer wall of the shell 1, and metal annular gaskets 9 matched with the second annular sealing grooves are arranged in the second annular sealing grooves.

[0030] In addition, the flanges at the ends of the balance pipe 3 are designed as non-standard flanges, which can prevent the connection joint 5 from loosening.

[0031] When the gas medium leaks from the balance disc sealing position of the centrifugal compressor into the balance cavity behind the balance disc, the gas medium in the balance cavity flows into the second balance gas opening 8, and then quickly flows from the second balance gas opening 8 to the connection joint 5 screwed in the connecting through hole 4, and then enters the balance pipe 3 from the connection joint 5, and finally flows back to the compressor inlet through the balance pipe 3 from the first balance gas opening 7, so that the pressure in the balance cavity approaches the pressure at the compressor inlet. Since the front of the balance disc is the high-pressure side, the pressure value is about the static pressure at the outlet of the last-stage impeller, so the pressure difference before and after the balance disc provides a force opposite to the total axial thrust on the impeller, thereby offsetting part of the axial force on the rotor, achieving the effect of adjusting the total residual axial force of the rotor.

[0032] In addition, in the process that the gas medium flows through the second balance gas opening 8, the connection joint 5 screwed in the connecting through hole 4, the balance pipe 3, and finally flows back to the compressor inlet through the first balance gas opening 7, since the connection joint 5 is screwed in the connecting through hole 4, the problem that the gas medium is easy to leak from the gap between the shell 1 and the end cover 2 when the gas medium directly enters the connecting through hole 4 from the second balance gas opening 8 is avoided. Moreover, the O-shaped sealing ring 6 is arranged between the outer side of the capped part of the connection joint 5 and the inner side of the counterbore of the connecting through hole 4, and the metal annular gasket 9 is arranged between the end flange of the balance pipe 3 and the outer wall of the shell 1, which further ensures the air tightness of the connection between the balance pipe 3 and the compressor, effectively avoids the leakage of the gas medium, and makes the centrifugal compressor have better air tightness.

[0033] Meanwhile, the centrifugal compressor balance gas pipe connecting structure provided by the utility model connects both ends of the balance gas pipe with the flange of the outer wall of the casing, and since the arrangement space at the outer wall of the casing is less limited, the flange nominal diameter DN and the number of the balance gas pipe flange are not limited and interfered by the size of the adjacent flange components such as the fixed clasp ring on the end cover and the oil return side cover inside the casing, so that the diameter DN and the number of the balance gas pipe can be designed according to the actual needs, thereby effectively solving the problem that the gas leaked from the balance disc to the balance cavity cannot be returned to the compressor inlet in time.

[0034] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the utility model and are not limited, although the utility model is described in detail with reference to the examples, those skilled in the art should understand that the technical solutions of the utility model can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the utility model, and they should be covered in the scope of the claims of the utility model.

Claims

1. A centrifugal compressor balance pipe connection structure, characterized in that, The compressor comprises a casing (1), an end cover (2) and a balance gas pipe (3), one end of the balance gas pipe (3) is flange connected with a first balance gas opening (7), the first balance gas opening (7) is arranged on the casing (1) and communicates with the compressor inlet, the other end of the balance gas pipe (3) is flange connected with a connecting through hole (4), the connecting through hole (4) is radially arranged on the casing (1) and extends into the end cover (2) connected with the casing (1) and communicates with one end of a second balance gas opening (8) in the end cover (2), the other end of the second balance gas opening (8) communicates with a balance cavity behind a balance disc of the casing (1).

2. The centrifugal compressor balance piston connection structure according to claim 1, characterized by: A section of the connecting through hole (4) in the casing (1) is a through hole with a counterbore, and a section of the connecting through hole (4) in the end cover (2) is a tapered internal thread hole.

3. The centrifugal compressor balance piston connection structure according to claim 2, characterized by: A cap connection joint (5) matched with the connecting through hole (4) is arranged in the connecting through hole (4), and an external thread is arranged at an end of the connection joint (5), the connection joint (5) is arranged in the connecting through hole (4) and is threadedly connected with the tapered internal thread hole in the end cover (2).

4. The centrifugal compressor balance piston connection structure according to claim 2, characterized by: First annular sealing grooves are respectively arranged on the outside of the cap part of the connection joint (5) and the inside of the counterbore of the connecting through hole (4), and O-shaped sealing rings (6) matched with the first annular sealing grooves are arranged in the first annular sealing grooves.

5. The centrifugal compressor balance piston connection structure according to claim 1, characterized by: Flanges are respectively arranged at two ends of the balance gas pipe (3), and threaded blind holes matched with connecting holes on the flanges at the two ends of the balance gas pipe (3) are respectively arranged on the outer wall of the casing (1) around the first balance gas opening (7) and the connecting through hole (4), and the balance gas pipe (3) is fixedly connected with the outer wall of the casing (1) by the connecting holes on the flanges at the two ends of the balance gas pipe (3) and the threaded blind holes on the outer wall of the casing (1) through connecting bolts.

6. The centrifugal compressor balance piston connection structure according to claim 5, characterized by: Second annular sealing grooves are respectively arranged on the inner side surfaces of the flanges at the two ends of the balance gas pipe (3) and the outer wall of the casing (1), and metal annular gaskets (9) matched with the second annular sealing grooves are arranged in the second annular sealing grooves.

7. The centrifugal compressor balance piston connection structure according to claim 2, characterized by: The flanges at the two ends of the balance gas pipe (3) are non-standard flanges.

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