JP2012144994A - Centrifugal compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal compressor having a non-contact seal capable of effectively preventing refrigerant from flowing into a housing when the centrifugal compressor is stopped.SOLUTION: The centrifugal compressor 1 having a non-contact type seal 30 sealing a rotary shaft 21 in a housing 20 housing the gear 26 attaching side of rotating shaft 21 in which an impeller 11 is attached to one end and the gear 26 is attached to the other end, has an operating condition detecting means 50 detecting the operation condition of the centrifugal compressor 1 and a stopping time seal mechanism 40 arranged in the housing 20 in the gear 26 side more than the non-contact type seal 30, being separated from the rotating shaft 21 when the centrifugal compressor 1 is operated, contacting the rotating shaft 21 to seal the shaft when the centrifugal compressor 1 is stopped according to the detection of the operating condition detecting means 50.

Description

  The present invention relates to a centrifugal compressor, and more particularly to a centrifugal compressor having a non-contact seal.

  2. Description of the Related Art Conventionally, as a shaft seal structure of a centrifugal compressor that rotates at high speed, a non-contact seal having a rotary ring provided on an impeller rotary shaft side and a fixed ring provided on a housing side is known.

  For example, in Patent Document 1, as a centrifugal compressor having such a non-contact type seal, a non-contact type seal having a rotating ring and a fixed ring is provided between the rotor chamber and the bearing portion. A shaft seal device of a centrifugal compressor that supplies a seal gas to a seal is disclosed.

Japanese Patent Publication No. 7-69022

  By the way, in the non-contact type seal as described above, when the centrifugal compressor is operated, the rotating ring having the spiral groove on the surface rotates integrally with the impeller rotating shaft, so that a constant amount is provided between the rotating ring and the fixed ring. Dynamic pressure acts. Therefore, a desired sealing effect can be exhibited during operation of the centrifugal compressor. However, when the centrifugal compressor is stopped, a slight gap is generated between the rotating ring and the stationary ring due to the spiral groove on the surface of the rotating ring, so that the sealing effect may not be sufficiently exhibited.

  Therefore, when a centrifugal compressor having a non-contact type seal is used as a compressor of a heat pump, for example, the refrigerant in the loop of the heat pump is rotated from the gap between the rotating ring and the stationary ring when the centrifugal compressor is operated. It may flow into the housing that houses the gear mounting side of the shaft.

  More specifically, immediately after the heat pump stops, that is, immediately after the centrifugal compressor stops, the heat pump loop is at a higher temperature and pressure than the gear-side housing, so there is a pressure difference between both ends of the non-contact seal. Arise. If a pressure difference occurs, the refrigerant in the loop of the heat pump may flow from the back surface of the impeller through the gap between the rotating ring and the stationary ring into the gear-side housing.

  The present invention has been made in view of such a point, and the object thereof is a centrifugal compressor having a non-contact seal that seals the impeller rotary shaft in a housing that houses the gear mounting side of the impeller rotary shaft. This is to effectively prevent the refrigerant from flowing into the gear-side housing from the non-contact seal when the centrifugal compressor is stopped.

  In order to achieve the above object, a centrifugal compressor according to the present invention has a non-seal that seals the rotary shaft in a housing that houses a gear mounting side of the rotary shaft that has an impeller attached to one end and a gear attached to the other end. A centrifugal compressor having a contact-type seal, wherein the operation state detection means detects an operation state of the centrifugal compressor, and the operation state detection means is provided in the housing on the gear side of the non-contact type seal. In response to the detection, a stop seal mechanism is provided that is separated from the rotary shaft during operation of the centrifugal compressor and that contacts the rotary shaft and seals the shaft when the centrifugal compressor is stopped.

  The stop-time seal mechanism includes an annular flange provided on the peripheral surface of the rotating shaft located on the gear mounting side with respect to the non-contact type seal, and an inner surface of the housing on the gear side with respect to the non-contact type seal. An annular protrusion that protrudes toward the annular flange and forms an annular space with the annular flange; a valve element that contacts the annular flange and the annular protrusion to close the annular space; and the valve Urging means for urging and contacting the body toward the annular flange and the annular protrusion, and the urging force of the urging means during operation of the centrifugal compressor in response to detection by the operating state detecting means. The valve body may be provided with valve opening means that separates the valve body from the annular flange and the annular protrusion.

  The stop-time sealing mechanism includes a first seal member that seals a contact surface between the valve body and the annular flange, and a second seal member that seals a contact surface between the valve body and the annular protrusion. May be further provided.

  According to the centrifugal compressor of the present invention, in the centrifugal compressor having the non-contact type seal that seals the impeller rotary shaft in the housing that houses the gear mounting side of the impeller rotary shaft, the refrigerant is not in the non-contact state when the centrifugal compressor is stopped. It is possible to effectively suppress the flow into the gear side housing relative to the contact seal.

It is a typical fragmentary sectional view showing the centrifugal compressor concerning one embodiment of the present invention. It is typical sectional drawing which shows the principal part of the centrifugal compressor which concerns on one Embodiment of this invention. It is a flow which shows the control content of the centrifugal compressor which concerns on one Embodiment of this invention.

  Hereinafter, based on FIGS. 1-3, the centrifugal compressor which concerns on one Embodiment of this invention is demonstrated. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A centrifugal compressor 1 according to an embodiment of the present invention is used as a centrifugal compressor of a high-temperature heat pump that raises a heat source of, for example, 100 ° C. to 150 ° C. to 150 ° C. to 180 ° C., as shown in FIG. , Impeller housing part 10, gear box part (housing) 20, non-contact seal 30, stop contact seal mechanism (stop seal mechanism) 40, rotation speed detection sensor (operating state detection means) 50, And a control unit 60.

  In the present embodiment, the centrifugal compressor 1 is described as being applied to a high-temperature heat pump, but can be widely applied to any type of heat pump that compresses refrigerant with a centrifugal compressor such as a refrigerator.

  As shown in FIG. 1, the impeller housing portion 10 houses an impeller 11 provided with a plurality of blades (not shown), a suction port portion 12 for taking in a refrigerant from an evaporator of a high-temperature heat pump (not shown), and the impeller 11. It has an impeller accommodating portion 13, an annular diffuser flow path 14 connected to the impeller accommodating portion 13, and a scroll flow path 15 connected to the outer peripheral edge of the diffuser flow path 14.

  As shown in FIG. 1, the impeller 11 is attached to an end portion of the impeller rotating shaft 21. And the impeller 11 discharges a refrigerant | coolant to radial outward by rotating integrally with the impeller rotating shaft 21 with the drive force of the motor 24 mentioned later.

  As shown in FIG. 1, the suction port portion 12 is provided on the upstream side of the impeller housing portion 10 so as to be coaxial with the impeller 11. Further, the suction port 12 is formed so that the opening area gradually decreases from the upstream side toward the downstream side.

  The impeller accommodating portion 13 is formed so that the opening area gradually increases from the upstream side toward the downstream side so as to accommodate the impeller 11. Further, the upstream side of the impeller accommodating portion 13 communicates with the suction port portion 12.

  The annular diffuser channel 14 is formed on the downstream side portion of the impeller housing portion 10 so as to surround the impeller housing portion 13. Further, a scroll passage 15 for discharging the refrigerant to a condenser (not shown) of a high-temperature heat pump is connected to the outer peripheral edge of the diffuser passage 14.

  That is, the impeller housing unit 10 compresses (increases) by discharging the refrigerant taken from the evaporator of the high-temperature heat pump through the suction port 12 to the scroll channel 15 by the rotation of the impeller 11. Temperature and pressure increase).

  As shown in FIG. 1, the gear box portion (housing) 20 accommodates the gear mounting side of the impeller rotary shaft 21, and includes a pair of bearings 22 and 23 provided inside the gear box portion 20, and a gear box. Motor 24 attached to the side of portion 20, driven gear 26 fitted to impeller rotary shaft 21, drive gear 27 fitted to motor drive shaft 25, and elastomer that seals motor drive shaft 25. And a motor shaft seal 28 made of a material.

  As shown in FIG. 1, the impeller rotating shaft 21 is rotatably supported in the gear box portion 20 by a pair of bearings 22 and 23. A driven gear 26 that meshes with the drive gear 27 is fitted to the impeller rotary shaft 21 located between the pair of bearings 22 and 23. Further, on the peripheral surface of the impeller rotating shaft 21 positioned between the bearing 22 and the impeller 11, a protruding portion 21 b is formed to which a rotating ring 31 constituting a part of a non-contact type seal 30 described later is attached. . Further, an annular flange 21a that constitutes a part of a stop-time contact seal mechanism 40, which will be described later, is formed on the peripheral surface of the impeller rotary shaft 21 located between the protrusion 21b and the bearing 22.

  As shown in FIG. 1, the motor drive shaft 25 of the motor 24 is inserted from the side of the gear box portion 20 and is rotatably supported by a bearing (not shown). The motor drive shaft 25 is fitted with a drive gear 27 having a larger diameter than the driven gear 26. A motor shaft seal 28 that seals the motor drive shaft 25 is provided on the side of the gear box portion 20 through which the motor drive shaft 25 is inserted. In addition, in the gear box part 20, lubricating oil is injected in order to suppress wear of the driven gear 26 and the driving gear 27 that mesh with each other.

  As shown in FIG. 1, the non-contact type seal 30 is provided in the gear box portion 20 adjacent to the back surface of the impeller 11. Further, the non-contact seal 30 includes a rotary ring 31 provided on the impeller rotary shaft 21 side and a fixed ring 32 provided on the gear box portion 20 side.

  The rotary ring 31 is fixed to the impeller rotary shaft 21 via the protrusion 21b. On the other hand, the stationary ring 32 is attached to an attachment portion 20b formed inside the gear box portion 20 so as to be movable in the axial direction via a coil spring (not shown). A plurality of spiral grooves (not shown) are provided on the side surface of the rotating ring 31 that faces the fixed ring 32.

  That is, when the rotating ring 31 rotates integrally with the impeller rotating shaft 21, the non-contact type seal 30 causes dynamic pressure to act between the rotating ring 31 and the fixed ring 32 by the plurality of spiral grooves, thereby preventing the impeller rotating shaft 21 from moving. It is configured to seal the shaft. This dynamic pressure separates the stationary ring 32 from the rotating ring 31 against the biasing force of the coil spring. On the other hand, when the impeller rotating shaft 21 is stopped, the rotating ring 31 and the stationary ring 32 come into contact with each other by the biasing force of the coil spring. In this contacted state, a slight gap due to the spiral groove exists between the rotating ring 31 and the fixed ring 32.

  As shown in FIGS. 2A and 2B, the stop-time contact seal mechanism 40 includes a seal body 41 having a cylindrical hollow portion, an annular valve body 42, a spring (biasing means) 43, and a presser. And a plate (valve opening means) 44.

  As shown in FIGS. 2A and 2B, the seal body 41 is placed in the gear box portion 20 between the non-contact seal 30 and the bearing 22 with the impeller rotary shaft 21 inserted through the hollow portion. It is fitted. An annular protrusion 41a projecting radially inward toward the top of the annular flange 21a is formed at one end of the inner peripheral surface of the seal body 41 located on the non-contact seal 30 side (X direction side in the drawing). Is provided. An annular space 45 is formed between the top of the annular protrusion 41a and the top of the annular flange 21a.

  On the other hand, a support protrusion 41 b that protrudes inward in the radial direction toward the impeller rotary shaft 21 is provided at the other end portion of the inner peripheral surface of the seal body 41 located on the bearing 22 side (Y direction side in the drawing). ing. One end of the spring 43 is locked to the side portion of the support protrusion 41b.

  Further, as shown in FIGS. 2A and 2B, an annular slot 41 c extending in the axial direction of the impeller rotating shaft 21 (XY direction in the drawing) is formed inside the seal body 41. An outer peripheral side portion 44b of a pressing plate 44 described later is slidably inserted into the annular slot 41c. Further, an electromagnet 46 whose excitation / demagnetization is controlled by a control unit 60 described later is provided inside the seal body 41 adjacent to the annular slot 41c.

  As shown in FIGS. 2A and 2B, the annular valve body 42 is slidably accommodated in the hollow portion of the seal body 41 with the impeller rotary shaft 21 loosely inserted. Further, the other end of the spring 43 is engaged with the annular side portion of the valve body 42 facing the side portion of the support protrusion 41b. That is, the valve body 42 is urged toward the annular flange 21a and the annular protrusion 41a by the spring 43 provided between the valve body 42 and the support protrusion 41b.

  Further, as shown in FIGS. 2A and 2B, the contact surface between the valve body 42 and the annular flange 21a is sealed on the annular side part of the valve body 42 facing the side part of the annular flange 21a. A ring-shaped inner seal member (first seal member) 48 is provided. Further, a ring-shaped outer seal member (second seal member) 47 that seals the contact surface between the valve body 42 and the annular protrusion 41a is provided on the annular side part of the valve body 42 that faces the side part of the annular protrusion 41a. Is provided. That is, the annular space 45 is closed when the valve body 42 contacts the annular flange 21a and the annular protrusion 41a by the biasing force of the spring 43, and the outer seal member 47 and the inner seal member 48 seal the contact surfaces. (See FIG. 2B).

  As shown in FIGS. 2A and 2B, the holding plate 44 includes an annular side portion 44a, an outer peripheral side portion 44b extending in the axial direction from the outer peripheral edge of the annular side portion 44a, and an annular side portion 44a. And an inner peripheral side portion 44c extending in the axial direction from the inner peripheral edge. The outer peripheral side portion 44 b is slidably inserted into the annular slot 41 c, and the inner peripheral side portion 44 c is inserted into the annular space 45. Then, when the electromagnet 46 is excited, the pressing plate 44 moves to the support protrusion 41b side (Y direction in the figure).

  That is, when the electromagnet 46 is excited, the stop-time contact seal mechanism 40 pushes the valve body 42 toward the support protrusion 41b (Y direction in the figure) against the urging force of the spring 43. Thus, the annular space 45 is configured to be opened (see FIG. 2A). At this time, since the valve body 42 and the inner seal member 48 are separated from the annular flange 21a, the contact seal mechanism 40 at the time of stop and the impeller rotary shaft 21 are in a non-contact state.

  On the other hand, when the electromagnet 46 is demagnetized, the contact seal mechanism 40 at the time of stop releases the pushing of the valve body 42 by the pressing plate 44, and the valve body 42 is moved to the annular protrusion 41a side by the urging force of the spring 43 (in the drawing). X direction side). And the valve body 42 contacts the annular flange 21a and the annular projection 41a, and the outer seal member 47 and the inner seal member 48 seal the contact surface to close the annular space 45, so that the impeller rotary shaft 21 is closed. It is comprised so that a shaft may be sealed (refer FIG.2 (b)).

  As shown in FIG. 1, the rotation speed detection sensor 50 is provided in the gear box portion 20 between the non-contact type seal 30 and the contact seal mechanism 40 when stopped. The rotational speed detection sensor 50 detects the rotational speed of the impeller rotary shaft 21 and outputs the rotational speed to the control unit 60 described later, and is connected to the control unit 60 via electrical wiring. In addition, as a driving | running state detection means, it replaces with the rotation speed detection sensor 50, and you may apply the stationary ring position detection sensor (not shown) which detects the position with respect to the rotation ring 31 of the stationary ring 32. FIG.

  The control unit 60 includes a known CPU, ROM, RAM, input port, output port, and the like. Further, the output signal of the rotation speed detection sensor 50 and the start signal from the compressor start panel are input to the control unit 60 after A / D conversion. Moreover, the control part 60 has the driving | running state determination part 61 and the electromagnet control part 62 as a one part function element, as shown in FIG.

  The operation state determination unit 61 determines the operation state of the centrifugal compressor 1 based on the output value of the rotation speed detection sensor 50 and the output value of the start signal. Specifically, when the output value of the rotation speed detection sensor 50 (hereinafter also referred to as the rotation speed N) is greater than 0 (zero), the operation state of the centrifugal compressor 1 is determined as being in operation. On the other hand, when the output value (rotational speed N) of the rotational speed detection sensor 50 is 0 (zero), it is determined that the operation state of the centrifugal compressor 1 is stopped.

  When a stationary ring position detection sensor is used instead of the rotational speed detection sensor 50, it is determined that the operation state of the centrifugal compressor 1 is stopped when the rotating ring 31 and the stationary ring 32 are in contact with each other, and the rotating ring 31 is used. What is necessary is just to determine that the driving | running state of the centrifugal compressor 1 is driving | operating at the time of the non-contact state to which 1 and the stationary ring 32 separate.

  The electromagnet controller 62 controls the excitation / demagnetization of the electromagnet 46 according to the determination result of the operation state determination unit 61. Specifically, when it is determined that the operation state of the centrifugal compressor 1 is in operation, the electromagnet controller 62 outputs a control signal for exciting the electromagnet 46. That is, when the electromagnet 46 is energized, the valve element 42 is pushed toward the support protrusion 41b by the pressing plate 44. And the shaft seal of the impeller rotating shaft 21 is open | released because the valve body 42 spaces apart from the annular flange 21a and the annular protrusion 41a (refer Fig.2 (a)).

  On the other hand, when it is determined that the operating state of the centrifugal compressor 1 is stopped, the electromagnet controller 62 outputs a control signal for demagnetizing the electromagnet 46. That is, when the electromagnet 46 is demagnetized, the pushing of the valve body 42 by the pressing plate 44 is released. Then, the valve body 42 comes into contact with the annular flange 21a and the annular protrusion 41a, and the outer seal member 47 and the inner seal member 48 seal the contact surfaces to close the annular space 45, whereby the impeller rotary shaft 21 is The shaft is sealed (see FIG. 2B).

  Since the centrifugal compressor 1 according to an embodiment of the present invention is configured as described above, for example, the following control is performed according to the flow shown in FIG.

In step (hereinafter, the step is simply referred to as S) 90, the start determination of the centrifugal compressor 1 is performed based on the start signal from the compressor start panel. When it is determined that the centrifugal compressor 1 is not activated, the rotational speed N of the impeller rotary shaft 21 detected by the rotational speed detection sensor 50 is read into the operating state determination unit 61 in S100. When the stationary ring position detection sensor is used, the position L ₁ of the stationary ring 32 with respect to the rotating ring 31 is detected and read. On the other hand, when it is determined that the centrifugal compressor 1 is activated, the process proceeds to S120.

  In S <b> 110, the operation state of the centrifugal compressor 1 is confirmed by the operation state determination unit 61. When the rotation speed N read in S100 is larger than 0 (N> 0) (N> 0), the operation state of the centrifugal compressor 1 is determined to be in operation, and the process proceeds to S120. On the other hand, when the rotation speed N read in S100 is 0 (N = 0), it is determined that the operation state of the centrifugal compressor 1 is stopped, and the process proceeds to S130.

When the stationary ring position detection sensor is used, in order to calculate the displacement L ₂ of the stationary ring 32 with respect to the rotating ring 31, the initial distance L ₀ between the rotating ring 31 and the stationary ring 32 is read at S 100. The position L ₁ of the stationary ring 32 is subtracted (L ₂ = L ₀ −L ₁ ). When the displacement L ₂ is larger than 0 (zero), it is determined that the operation state of the centrifugal compressor 1 is in operation. On the other hand, when the displacement L ₂ is 0 (zero), it is determined that the operation state of the centrifugal compressor 1 is stopped.

  In S <b> 120, the electromagnet 46 is excited by the electromagnet controller 62. That is, the holding plate 44 pushes the valve body 42, the valve body 42 is separated from the annular flange 21a and the annular protrusion 41a, and this control is returned.

  On the other hand, in S130, the electromagnet 46 is demagnetized by the electromagnet controller 62 in response to the determination that the operation state of the centrifugal compressor 1 is stopped in S110. In other words, the pushing of the valve body 42 by the holding plate 44 is released, the valve body 42 contacts the annular flange 21a and the annular protrusion 41a, and the outer seal member 47 and the inner seal member 48 seal the contact surface. This control is returned.

  With the configuration as described above, the centrifugal compressor 1 according to one embodiment of the present invention has the following operations and effects.

  Immediately after the centrifugal compressor 1 is stopped, the inside of the loop of the high-temperature heat pump becomes higher in temperature and pressure than in the gear box portion 20, and the refrigerant in the loop is between the rotating ring 31 and the stationary ring 32 of the non-contact type seal 30. Through the slight gap, the air tends to flow into the gear box portion 20 on the gear 26 side of the non-contact type seal 30.

  Here, in the centrifugal compressor 1 according to the present embodiment, when the centrifugal compressor 1 is stopped, the electromagnet 46 is demagnetized and the pushing of the valve body 42 by the pressing plate 44 is released. Then, the valve body 42 comes into contact with the annular flange 21a and the annular projection 41a by the biasing force of the spring 43, and the outer seal member 47 and the inner seal member 48 seal the contact surface to close the annular space 45. The impeller rotary shaft 21 is sealed.

  Therefore, since the impeller rotary shaft 21 is reliably sealed simultaneously with the stop of the centrifugal compressor 1 by the stop contact seal mechanism 40, the gear box on the gear 26 side than the non-contact seal 30 on which the refrigerant is on the low pressure side. The flow into the portion 20 can be effectively suppressed.

  Further, since the refrigerant is prevented from flowing into the gear box portion 20 on the gear 26 side relative to the non-contact type seal 30, for example, a refrigerant that is highly meltable in lubricating oil in a heat pump or an elastomer material used as a seal Even when a highly erodible refrigerant is used, it is possible to effectively prevent the deterioration of the lubricating oil due to the melting of the refrigerant and the deterioration of the motor shaft seal 28 due to the erosion of the refrigerant.

  The impeller rotary shaft 21 is sealed with a non-contact seal 30 when the centrifugal compressor 1 is in operation, and is reliably sealed with a stop-time contact seal mechanism 40 when the centrifugal compressor 1 is stopped.

  Therefore, even when a malfunction occurs in the gear box portion 20 or the motor shaft seal 28, air or lubricating oil leaks from the gear box portion 20 closer to the gear 26 than the non-contact seal 30 into the loop of the high-temperature heat pump. This can be effectively prevented.

  Further, the contact seal mechanism 40 at the time of stopping does not supply the seal gas or the like to the non-contact type seal 30, and the impeller rotary shaft 21 is configured with a simple configuration such as the seal body 41, the valve body 42, the spring 43, and the pressing plate 44. Since the shaft can be reliably sealed, maintenance and management of the centrifugal compressor 1 can be facilitated.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  In the above-described embodiment, the outer seal member 47 and the inner seal member 48 have been described as being provided on the annular side portion of the valve body 42. However, the inner seal member 48 is provided on the side portion of the annular flange 21a, and the outer seal member is provided. 47 may be provided on the side of the annular protrusion 41a.

  Further, the biasing means is not necessarily the spring 43, and a leaf spring, a hydraulic cylinder, or the like may be applied as long as it biases the valve body 42. When a hydraulic cylinder is used as the biasing means, it can also be used as the valve opening means.

1 Centrifugal Compressor 11 Impeller 20 Gearbox (Housing)
21 Impeller rotating shaft (Rotating shaft)
21a Annular flange 30 Non-contact seal 40 Stop contact seal mechanism (stop seal mechanism)
41a annular projection 42 valve element 43 spring (biasing means)
44 Holding plate (Valve opening means)
50 Rotational speed detection sensor (operating state detection means)

Claims (3)

A centrifugal compressor having a non-contact seal that seals the rotating shaft in a housing that houses a gear mounting side of the rotating shaft that has an impeller attached to one end and a gear attached to the other end,
An operation state detecting means for detecting an operation state of the centrifugal compressor;
Provided in the housing on the gear side with respect to the non-contact type seal, separated from the rotating shaft during operation of the centrifugal compressor according to detection of the operation state detection means, and when the centrifugal compressor is stopped A centrifugal compressor characterized by comprising: a sealing mechanism for stopping when the shaft is sealed in contact with the rotating shaft. The stopping seal mechanism is
An annular flange provided on the peripheral surface of the rotating shaft located on the gear mounting side with respect to the non-contact type seal;
An annular protrusion that protrudes from the inner surface of the housing closer to the gear than the non-contact seal toward the annular flange, and forms an annular space between the annular flange;
A valve body that contacts the annular flange and the annular protrusion to close the annular space;
Biasing means for biasing and contacting the valve body toward the annular flange and the annular projection;
A valve opening means for separating the valve body from the annular flange and the annular protrusion against the urging force of the urging means during operation of the centrifugal compressor in response to detection of the operating state detecting means; The centrifugal compressor according to claim 1, comprising: The stopping seal mechanism is
A first seal member for sealing a contact surface between the valve body and the annular flange;
The centrifugal compressor according to claim 2, further comprising: a second seal member that seals a contact surface between the valve body and the annular protrusion.

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