Centrifugal compressor

Abstract

To suppress impact on the assemblability of a centrifugal compressor having a bundle in whatever way the size of a discharge scroll is changed.SOLUTION: A centrifugal compressor includes: a rotational shaft having an impeller; and a casing having an inlet and an outlet. The casing includes: a diaphragm covering the rotational shaft; an external casing covering the diaphragm; a discharge scroll for guiding work fluid discharged from the impeller to the outlet; and a flow path forming member having a scroll external peripheral surface positioned on a radially outer side and facing a radially inner side in the discharge scroll. The rotational shaft and the diaphragm form a bundle housed in a state such that it can be inserted and extracted to / from the external casing. The flow path forming member has an outer diameter smaller than an outer diameter of the bundle in the radial direction, extends in a circumferential direction, and is fixed to the diaphragm from an axial direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to centrifugal compressors. [Background technology]

[0002] A multi-stage centrifugal compressor, which has multiple stages of impellers that compress gas, is known as a type of centrifugal rotating machine. In a multi-stage centrifugal compressor, gas is drawn into a casing through a suction port, compressed sequentially by multiple stages of impellers, and discharged from the casing through a discharge port. A discharge scroll is connected to the discharge port, which maintains a constant flow rate of the gas discharged from the impeller through a diffuser passage and reduces its pressure.

[0003] For example, Patent Document 1 describes a discharge volute (discharge scroll) that is formed so that the radial spacing gradually increases toward the downstream side in the circumferential direction of gas flow. This discharge volute is formed by fixing volute pieces to a casing, the radial thickness of which gradually decreases toward the downstream side in the circumferential direction of gas flow. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 3239534 Summary of the Invention [Problem to be solved by the invention]

[0005] In the structure of Patent Document 1, the volute piece is fixed radially to the casing body that covers the bundle. Reducing the size of the discharge scroll results in a larger volute piece. As a result, the amount of protrusion of the volute piece from the inner circumferential surface of the casing body increases. A bundle having a diaphragm is inserted inside the casing body, and an increase in the size of the volute piece could cause interference with the bundle. This could affect the assembly of the centrifugal compressor. Therefore, it is desirable to ensure that the assembly of a centrifugal compressor having a bundle is not affected, regardless of how the size of the discharge scroll is changed.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a centrifugal compressor that can suppress the effect on the assembly of a centrifugal compressor having a bundle, regardless of how the size of the discharge scroll is changed. [Means for solving the problem]

[0007] In order to solve the above problems, a centrifugal compressor according to the present disclosure includes a rotating shaft extending in an axial direction in which a central axis extends, and a casing having an inlet port formed on a first side in the axial direction and a discharge port formed on a second side in the axial direction, the rotating shaft having an impeller disposed within the casing and compressing and discharging a working fluid supplied from the first side in the axial direction outward in a radial direction based on the central axis, the casing including a diaphragm formed in a cylindrical shape extending in the axial direction so as to cover the rotating shaft, an outer casing formed in a cylindrical shape extending in the axial direction so as to cover the diaphragm, a diffuser flow path that guides the working fluid discharged from the impeller outward in the radial direction, and a compressor for the impeller. the discharge scroll is connected to the diffuser flow path on the outside in the radial direction and extends in a circumferential direction around the central axis, the rotating shaft and the diaphragm are formed in a cylindrical shape extending in the axial direction and form a bundle housed in the outer casing in a state where they can be inserted and removed in the axial direction, and the flow path forming member is formed with an outer diameter smaller than the outer diameter of the bundle in the radial direction, extends in the circumferential direction, and is fixed to the diaphragm in the axial direction. [Effects of the Invention]

[0008] According to the centrifugal compressor of the present disclosure, no matter how the size of the discharge scroll is changed, the effect on the assembly of the centrifugal compressor having the bundle can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a centrifugal compressor according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the configuration of the discharge scroll and its surroundings of the centrifugal compressor. [Figure 3] FIG. 2 is a cross-sectional view showing a discharge scroll of the centrifugal compressor as viewed from the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a centrifugal compressor 1 according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to this embodiment.

[0011] (Configuration of centrifugal compressor) 1, the centrifugal compressor 1 in this embodiment is a single-shaft multi-stage centrifugal compressor. The centrifugal compressor 1 mainly includes a rotating shaft 2 that rotates around a central axis O, and a casing 10 formed to surround the rotating shaft 2.

[0012] (Configuration of the rotating shaft) The rotating shaft 2 extends in the axial direction Da. The rotating shaft 2 extends so as to penetrate the inside of the casing 10 along the central axis O. The rotating shaft 2 has a rotating shaft main body 21 and an impeller 22.

[0013] In this embodiment, the direction in which the central axis O extends is referred to as the axial direction Da. The axial direction Da of the rotating shaft 2 is along a horizontal plane. In other words, the central axis O extends horizontally. The radial direction based on the central axis O is simply referred to as the radial direction Dr. Furthermore, the direction around the rotating shaft 2 centered on the central axis O is referred to as the circumferential direction Dc.

[0014] The rotating shaft body 21 is formed in a cylindrical shape extending in the axial direction Da. An end portion of the rotating shaft body 21 on a first side Da1 in the axial direction Da is supported by the casing 10 by a journal bearing 32A and a thrust bearing 31 so as to be rotatable about the central axis O. An end portion of the rotating shaft body 21 on a second side Da2 in the axial direction Da is supported by the casing 10 by a journal bearing 32B so as to be rotatable about the central axis O.

[0015] The impeller 22 is disposed on the outer side Dro of the rotating shaft main body 21 in the radial direction Dr based on the central axis O. A plurality of impellers 22 are disposed in the casing 10, spaced apart in the axial direction Da. In the present embodiment, for example, six impellers 22 are disposed at intervals in the axial direction Da. These impellers 22 constitute two sets of three-stage impeller groups 22A and 22B facing opposite each other in the axial direction Da. This makes the centrifugal compressor 1 of the present embodiment a so-called back-to-back single-shaft multi-stage centrifugal compressor. The centrifugal compressor 1 has a first compression section 20A having an impeller group 22A and a second compression section 20B having an impeller group 22B. In the centrifugal compressor 1, the working fluid compressed in the first compression section 20A is further compressed in the second compression section 20B.

[0016] Each impeller 22 compresses and discharges a working fluid (e.g., gas) supplied from a first side Da1 in the axial direction Da to an outer side Dro in the radial direction Dr. An impeller flow path 23 is formed inside each impeller 22. The cross-sectional area of the impeller flow path 23 gradually decreases from the inner side Dri in the radial direction Dr to the outer side Dro in the radial direction Dr. As a result, while the impeller 22 is rotating, the working fluid flowing through the impeller flow path 23 is gradually compressed and becomes highly pressurized. Note that each impeller 22 may be a closed impeller having a cover or an open impeller without a cover.

[0017] (Casing configuration) The casing 10 is formed to surround the rotary shaft main body 21 and the plurality of impellers 22 from the outer side Dro in the radial direction Dr. The casing 10 includes an outer casing 11, a suction port 111, a discharge port 112, an intermediate suction port 113, an intermediate discharge port 114, a plurality of diaphragms 15, a head 17, and rollers 18.

[0018] The outer casing 11 is formed in a cylindrical shape extending in the axial direction Da. The outer casing 11 is formed to cover the rotating shaft 2, the multiple diaphragms 15, the head 17, and the rollers 18 from the outer side Dro in the radial direction Dr. The outer casing 11 forms an inlet 111, an outlet 112, an intermediate inlet 113, and an intermediate outlet 114.

[0019] The suction port 111 is formed on a first side Da1 in the axial direction Da of the outer casing 11. The suction port 111 allows the working fluid to flow into the outer casing 11 from the outside.

[0020] The intermediate discharge port 114 is formed near the center of the external casing 11 in the axial direction Da. The intermediate discharge port 114 is formed away from the suction port 111 on the second side Da2 in the axial direction Da. The intermediate discharge port 114 is a discharge port in the first compression section 20A. The intermediate discharge port 114 is connected to the impeller 22 in the first compression section 20A that is located furthest to the second side Da2 in the axial direction Da. The intermediate discharge port 114 discharges the working fluid compressed inside the external casing 11 through the three impellers 22 of the first compression section 20A to the outside of the external casing 11.

[0021] The intermediate suction port 113 is formed on the second side Da2 in the axial direction Da of the external casing 11. The intermediate suction port 113 is formed away from the intermediate discharge port 114 on the second side Da2 in the axial direction Da. The intermediate suction port 113 is an suction port in the second compression section 20B. The intermediate suction port 113 is connected to the impeller 22 in the second compression section 20B that is located furthest to the second side Da2 in the axial direction Da. The intermediate suction port 113 allows the working fluid that has passed through the three impellers 22 of the first compression section 20A in the external casing 11 and is discharged from the intermediate discharge port 114 to flow into the impeller 22 of the second compression section 20B.

[0022] The discharge port 112 is formed near the center of the outer casing 11 in the axial direction Da. The discharge port 112 is formed away from the suction port 111 on the second side Da2 in the axial direction Da. The discharge port 112 is also formed away from the intermediate suction port 113 on the first side Da1 in the axial direction Da. The discharge port 112 is connected to the impeller 22 in the second compression section 20B that is located closest to the first side Da1 in the axial direction Da. Therefore, the discharge port 112 discharges the working fluid compressed through all the impellers 22 in the outer casing 11 to the outside of the outer casing 11.

[0023] The multiple diaphragms 15 are arranged on the inner side Dri in the radial direction Dr of the outer casing 11. The multiple diaphragms 15 are formed as a whole in a cylindrical shape extending in the axial direction Da so as to cover the rotating shaft 2 from the outer side Dro in the radial direction Dr. The multiple diaphragms 15 are fixed to each other to cover the periphery of the rotating shaft 2 and form a casing flow path 40 therein that connects the multiple impellers 22. The multiple diaphragms 15 each have a multiple diaphragm main body 151 and an intermediate wall 152.

[0024] The diaphragm bodies 151 cover the impellers 22 at each stage. Each diaphragm body 151 is formed in a disk shape centered on the central axis O. The multiple diaphragm bodies 151 are stacked in the axial direction Da. Adjacent diaphragm bodies 151 are fixed to each other by welding or detachable fastening members.

[0025] These diaphragm bodies 151 constitute two sets of three-stage diaphragm body groups 151A and 151B spaced apart in the axial direction Da. As a result, in this embodiment, the diaphragm body group 151A covers the impeller group 22A in the first compression section 20A, and the diaphragm body group 151B covers the impeller group 22B in the second compression section 20B.

[0026] Intermediate wall 152 is disposed between two diaphragm body groups 151A and 151B. Intermediate wall 152 covers rotating shaft body 21. Intermediate wall 152 forms a seal with the outer circumferential surface of rotating shaft body 21. Intermediate wall 152 is fixed to diaphragm body 151 by welding or by a detachable fastening member.

[0027] The multiple diaphragms 15, together with the rotating shaft 2, head 17, journal bearings 32A and 32B, thrust bearing 31, and rollers 18, form a bundle 30. The bundle 30 is housed in the outer casing 11 on the inner side Dri of the radial direction Dr, in a state where it can be inserted and removed in the axial direction Da. The bundle 30 is formed in a cylindrical shape extending in the axial direction Da. In the bundle 30, the multiple diaphragms 15, the rotating shaft 2, head 17, journal bearings 32A and 32B, thrust bearing 31, and rollers 18 are movable together to form a single unit.

[0028] The diaphragms 15 also have, as the casing flow passage 40, an inlet flow passage 41, a diffuser flow passage 42, and a return flow passage 43. The inlet flow passage 41, the diffuser flow passage 42, and the return flow passage 43 are formed in the first compression section 20A and the second compression section 20B, respectively.

[0029] The introduction flow path 41 guides the working fluid from the outer side Dro in the radial direction Dr toward the inner side Dri in the radial direction Dr. The introduction flow path 41 changes the working fluid heading toward the inner side Dri in the radial direction Dr into a flow toward the second side Da2 in the axial direction Da, and guides it to the impeller 22. In this way, the introduction flow path 41 changes the flow direction of the working fluid to the second side Da2 in the axial direction Da, and guides it to the impeller flow path 23 of the impeller 22.

[0030] The diffuser passage 42 extends from the inner side Dri to the outer side Dro in the radial direction Dr. An end of the diffuser passage 42 on the inner side Dri in the radial direction Dr is connected to an end of the impeller passage 23 on the outer side Dro in the radial direction Dr. The diffuser passage 42 guides the working fluid compressed by the impeller 22 from the inner side Dri in the radial direction Dr to the outer side Dro in the radial direction Dr.

[0031] The return flow passage 43 reverses the flow direction of the working fluid that has passed through the diffuser flow passage 42 and flowed from the inner side Dri in the radial direction Dr to the outer side Dro in the radial direction Dr. The return flow passage 43 guides the working fluid flowing toward the outer side Dro in the radial direction Dr to the inner side Dri in the radial direction Dr. One end of the return flow passage 43 (one side in the axial direction Da), which is upstream in the flow direction of the working fluid, is connected to the diffuser flow passage 42. The other end of the return flow passage 43 (the opposite side in the axial direction Da), which is downstream in the flow direction of the working fluid, is connected to the subsequent introduction flow passage 41.

[0032] A pair of heads 17 are arranged to close openings at both ends in the axial direction Da of the cylindrical outer casing 11. They are annular members centered on the central axis O. The pair of heads 17 are arranged inside the outer casing 11. The heads 17 of this embodiment have a first casing head 171 and a second casing head 172.

[0033] The first casing head 171 is disposed so as to close an opening on a first side Da1 in the axial direction Da of the outer casing 11. In other words, the first casing head 171 is disposed adjacent to the first side Da1 in the axial direction Da of the multiple diaphragms 15. A suction scroll that takes in external working fluid into the casing flow path 40 through the suction port 111 is formed between the first casing head 171 and the first-stage diaphragm body 151, which is disposed on the furthest first side Da1 in the axial direction Da among the multiple diaphragms 15. The first casing head 171 is fixed to the integrated multiple diaphragms 15 by detachable fastening members. In this way, the first casing head 171 is integrated with the multiple diaphragms 15.

[0034] The second casing head 172 is disposed so as to close an opening on the second side Da2 in the axial direction Da of the outer casing 11. In other words, the second casing head 172 is disposed adjacent to the second side Da2 in the axial direction Da with respect to the multiple diaphragms 15. Therefore, the second casing head 172 is adjacent to the final-stage diaphragm body 151 of the multiple diaphragms 15, which is disposed furthest to the second side Da2 in the axial direction Da. The second casing head 172 is fixed to the integrated multiple diaphragms 15 by detachable fastening members. In this way, the second casing head 172 is integrated with the multiple diaphragms 15.

[0035] The rollers 18 are disposed below the bundle 30 in the vertical direction. The rollers 18 come into contact with the inner circumferential surface of the lower part of the outer casing 11 when the bundle 30 is inserted into the outer casing 11. The casing 10 of this embodiment has a first roller 181 and a second roller 182 as the rollers 18.

[0036] The first roller 181 is disposed at an end of the first side Da1 of the bundle 30 in the axial direction Da. The first roller 181 is disposed at the leading end of the bundle 30 when it is inserted into the external casing 11. In other words, the first roller 181 is disposed at the bottom of the first casing head 171. A plurality of first rollers 181 are disposed at intervals in the circumferential direction Dc around the central axis O with respect to the bundle 30 (see FIG. 3). The first rollers 181 are disposed so as to come into contact with the inner circumferential surface of the lower part of the external casing 11 when the bundle 30 is inserted into the external casing 11.

[0037] The second roller 182 is arranged at an interval on the first side Da1 in the axial direction Da with respect to the first roller 181. A plurality of second rollers 182 are arranged at intervals in the circumferential direction Dc with respect to the bundle 30 (see FIG. 3). The second roller 182 is arranged near the middle of the bundle 30 in the axial direction Da. The first roller 181 is arranged in a lower part of the diaphragm body 151 adjacent to the second side Da2 in the axial direction Da with respect to the intermediate wall 152. The second roller 182 is arranged so as to come into contact with the inner circumferential surface of the lower part of the external casing 11 with the bundle 30 inserted into the external casing 11. The second roller 182 is arranged at a position where the position of the second roller 182 in the circumferential direction Dc with respect to the bundle 30 coincides with that of the first roller 181.

[0038] (Configuration of discharge scroll) Furthermore, the casing 10 of the centrifugal compressor 1 includes a discharge scroll 50, a flow path forming member 60, and an outer forming member 70. The discharge scroll 50 guides the working fluid discharged from the impeller 22 to the discharge port 112. The discharge scroll 50 guides the working fluid compressed in each of the first compression section 20A and the second compression section 20B and discharged from the final-stage impeller 22 to the discharge port 112. As shown in FIG. 2, the discharge scroll 50 is connected to the diffuser flow path 42 at an outer side Dro in the radial direction Dr. As shown in FIG. 3, the discharge scroll 50 extends in a circumferential direction Dc about the central axis O. The discharge scroll 50 is a flow path formed in a spiral shape around one circumference in the circumferential direction Dc around the central axis O. The discharge scroll 50 is connected to the diffuser flow path 42 at an inner side Dri in the radial direction Dr around the entire circumference. The discharge scroll 50 is connected to the discharge port 112 at an outer side Dro in the radial direction Dr in a part of the circumferential direction Dc. The discharge scroll 50 is formed so that the spacing in the radial direction Dr changes when viewed from the axial direction Da. The discharge scroll 50 is formed so that the spacing in the axial direction Da remains constant while only the spacing in the radial direction Dr decreases as the discharge scroll 50 moves away from the discharge port 112 in the circumferential direction Dc. In other words, the discharge scroll 50 is formed so that the spacing in the radial direction Dr is widest at the position closest to the discharge port 112 in the circumferential direction Dc. The spacing in the radial direction Dr of the discharge scroll 50 gradually narrows so that the flow velocity of the working fluid flowing inside the discharge scroll 50 remains constant in the circumferential direction Dc.

[0039] 2, the discharge scroll 50 is defined by a space formed in the multiple diaphragms 15, the outer casing 11, and the flow path forming member 60. The discharge scroll 50 of this embodiment is formed in a space surrounded by the diaphragm main body 151, the intermediate wall 152, the outer casing 11, and the flow path forming member 60. The discharge scroll 50 is surrounded by a scroll inner circumferential surface 51 on the inside Dri in the radial direction Dr, a scroll outer circumferential surface 52 on the outside Dro in the radial direction Dr, a first flow path forming surface 53 disposed on the second side Da2 in the axial direction Da, and a second flow path forming surface 54 disposed on the second side Da2 in the axial direction Da.

[0040] The scroll inner circumferential surface 51 is located at the innermost position Dri in the radial direction Dr of the discharge scroll 50. The scroll inner circumferential surface 51 is a surface that faces the outer side Dro in the radial direction Dr. The scroll inner circumferential surface 51 is formed by the diaphragm main body 151. When viewed from the circumferential direction Dc, the scroll inner circumferential surface 51 is disposed on the outer side Dro in the radial direction Dr with respect to the diffuser flow path 42. When viewed from the circumferential direction Dc, the scroll inner circumferential surface 51 is disposed on the inner side Dri in the radial direction Dr with respect to the boundary between the second casing head 172 and the diaphragm 15 and the outer casing 11.

[0041] The scroll outer peripheral surface 52 is located at the outermost position Dro in the radial direction Dr of the discharge scroll 50. The scroll outer peripheral surface 52 faces the inner side Dri in the radial direction Dr. The scroll outer peripheral surface 52 faces the scroll inner peripheral surface 51 in the radial direction Dr. The scroll outer peripheral surface 52 is formed by a flow path forming member 60. The scroll outer peripheral surface 52 is disposed on the inner side Dri in the radial direction Dr with respect to the outer casing 11. When viewed from the circumferential direction Dc, the scroll outer peripheral surface 52 is disposed on the inner side Dri in the radial direction Dr with respect to the inner circumferential surface of the outer casing 11. The scroll outer peripheral surface 52 is formed so that the distance between the scroll outer peripheral surface 52 and the scroll inner circumferential surface 51 in the radial direction Dr decreases as the scroll outer peripheral surface 52 moves away from the discharge port 112 in the circumferential direction Dc.

[0042] The first flow passage forming surface 53 is located closest to the first side Da1 in the axial direction Da of the discharge scroll 50. The first flow passage forming surface 53 is a surface facing the second side Da2 in the axial direction Da. The first flow passage forming surface 53 is formed by the intermediate wall 152. The first flow passage forming surface 53 is formed in a flat shape so as to be integrally connected to the surface that forms the diffuser flow passage 42 at the same position in the axial direction Da.

[0043] The second flow passage forming surface 54 is located closest to the second side Da2 in the axial direction Da in the discharge scroll 50. The second flow passage forming surface 54 faces the first flow passage forming surface 53 in the axial direction Da. The second flow passage forming surface 54 is a surface facing the first side Da1 in the axial direction Da. The distance between the first flow passage forming surface 53 and the second flow passage forming surface 54 in the axial direction Da is constant at any position in the circumferential direction Dc. The second flow passage forming surface 54 is formed by the diaphragm main body 151. The second flow passage forming surface 54 extends from the scroll inner circumferential surface 51 to the outer side Dro in the radial direction Dr.

[0044] The flow path forming member 60 has a scroll outer peripheral surface 52. The flow path forming member 60 has an inner peripheral surface facing the inner side Dri in the radial direction Dr as the scroll outer peripheral surface 52, and forms a part of the discharge scroll 50. Therefore, the flow path forming member 60 is disposed on the outer side Dro in the radial direction Dr relative to the discharge scroll 50. The flow path forming member 60 is formed with an outer diameter smaller than the outer diameter of the bundle 30 in the radial direction Dr. When viewed from the circumferential direction Dc, the flow path forming member 60 of this embodiment is disposed such that its outer peripheral surface is aligned with the outer peripheral surfaces of the multiple diaphragms 15 and with the inner peripheral surface of the outer casing 11. The flow path forming member 60 extends in the circumferential direction Dc. The flow path forming member 60 is formed in a solid shape. As shown in FIG. 3, the flow path forming member 60 is formed in a plate shape that gradually becomes thinner in the circumferential direction Dc. When viewed from the axial direction Da, the flow path forming member 60 is not formed in an annular shape that covers the entire circumference of the rotating shaft 2, but forms an arc that covers more than half of the rotating shaft 2. The flow path forming member 60 is fixed to the diaphragm 15 in the axial direction Da. As shown in FIGS. 2 and 3 , the flow path forming member 60 of this embodiment is detachably fixed to the intermediate wall 152 by bolts 65 at multiple locations spaced apart in the circumferential direction Dc. As shown in FIG. 3 , the flow path forming member 60 is composed of multiple (two in this embodiment) small flow path forming pieces 69 divided in the circumferential direction Dc. In this embodiment, when viewed from the axial direction Da, the flow path forming member 60 is composed of an upper small flow path forming piece 69 vertical to the central axis O and a lower small flow path forming piece 69 vertical to the central axis O. Each small flow path forming piece 69 is fixed at multiple locations by bolts 65.

[0045] As shown in FIG. 2, the outer forming member 70 is disposed between the outer casing 11 and the flow path forming member 60 in contact with the flow path forming member 60 at the outer side Dro in the radial direction Dr. The outer forming member 70 is fixed to the outer casing 11. The outer forming member 70 is welded to the outer casing 11 in the radial direction Dr and is fixed in an undetachable manner. The outer forming member 70 supports the flow path forming member 60 relative to the outer casing 11 in a state where the flow path forming member 60 cannot move to the outer side Dro in the radial direction Dr. The outer forming member 70 is formed to cover the flow path forming member 60 from the outer side Dro in the radial direction Dr. A space is formed between the outer forming member 70 and the outer casing 11. As shown in FIG. 3, when viewed from the axial direction Da, the outer forming member 70 is not formed in an annular shape that covers the entire circumference of the rotating shaft 2, but forms a longer arc in the circumferential direction Dc than the flow path forming member 60.

[0046] As shown in FIG. 2 , the outer forming member 70 of this embodiment includes a support member 71 and a fixing member 72. The support member 71 faces the flow path forming member 60. The inner circumferential surface of the support member 71, which faces the inner side Dri in the radial direction Dr, is in contact with the outer circumferential surface of the flow path forming member 60. In other words, when viewed from the circumferential direction Dc, the inner circumferential surface of the support member 71 is disposed at the same position as the inner circumferential surface of the outer casing 11. The support member 71, which is in contact with the outer circumferential surface of the flow path forming member 60, is formed in a thin plate shape and extends in the circumferential direction Dc. The fixing member 72 fixes the support member 71 to the outer casing 11. The fixing member 72 extends in the radial direction Dr from the surface of the support member 71 facing the outer side Dro in the radial direction Dr. Two fixing members 72 are disposed spaced apart in the axial direction Da. The fixing members 72 are formed integrally with the support member 71. The fixing member 72 is fixed to the inner peripheral surface of the outer casing 11 by welding.

[0047] The outer forming member 70 also has through holes 73. The through holes 73 penetrate the support member 71 in the radial direction Dr. By penetrating the support member 71, the through holes 73 communicate the space in which the flow path forming member 60 is disposed with the space between the support member 71 and the outer casing 11. A plurality of through holes 73 are formed at intervals in the circumferential direction Dc and the axial direction Da.

[0048] 3, the outer forming member 70 is divided into a plurality of (five in this embodiment) small outer forming pieces 79 in the circumferential direction Dc. The small outer forming pieces 79 are fixed to the outer casing 11 by welding.

[0049] Furthermore, the outer forming member 70 has a recess 74. When viewed from the axial direction Da, the recess 74 is recessed in the radial direction Dr at the same position as the roller 18 in the circumferential direction Dc. The recess 74 is recessed from the surface of the support member 71 facing the inner side Dri in the radial direction Dr. When viewed from the axial direction Da, the recess 74 is formed with a certain length in the circumferential direction Dc so as to overlap with the area where the multiple first rollers 181 and the multiple second rollers 182 are arranged. The recess 74 in this embodiment is formed in the support member 71 of the small outer forming piece 79 that is located vertically lowest among the multiple small outer forming pieces 79.

[0050] (Action and effect) In the centrifugal compressor 1 having the above configuration, the working fluid discharged from the final-stage impeller 22 passes through the final-stage diffuser passage 42 and flows into the discharge scroll 50. The discharge scroll 50 has a scroll outer peripheral surface 52 located on the outer side Dro in the radial direction Dr, which is formed by a flow passage forming member 60. This flow passage forming member 60 is formed as a separate member from the outer casing 11 and the multiple diaphragms 15. Therefore, by changing the size of the flow passage forming member 60, the size of the discharge scroll 50 can be changed without changing the shapes of the outer casing 11 and the multiple diaphragms 15.

[0051] Furthermore, because the flow path forming member 60 is a plate-like member extending in the circumferential direction Dc, the scroll outer peripheral surface 52 also has a shape that extends smoothly in the circumferential direction Dc. Therefore, the scroll outer peripheral surface 52 of the flow path forming member 60 allows the working fluid that has flowed in from the diffuser flow path 42 to flow smoothly to the discharge port 112. This ensures the performance of the scroll flow path.

[0052] In addition, the flow path forming member 60 is formed with an outer diameter smaller than the outer diameter of the bundle 30 in the radial direction Dr, and is fixed to the intermediate wall 152 in the axial direction Da. Therefore, no matter how the size of the discharge scroll 50 is changed, the flow path forming member 60 does not protrude outside Dro from the multiple diaphragms 15 in the radial direction Dr. In other words, no matter how the size of the discharge scroll 50 is changed, the flow path forming member 60 does not interfere with the outer casing 11. Therefore, assembly is not hindered when inserting or removing the external casing 11 and the bundle 30. As a result, no matter how the size of the discharge scroll 50 is changed, the impact on assembly of the centrifugal compressor 1 having the bundle 30 can be suppressed.

[0053] Furthermore, the flow path forming member 60 is formed in a solid shape. Therefore, even if the high-pressure working fluid discharged from the final-stage impeller 22 flows into the discharge scroll 50, deformation of the flow path forming member 60 can be suppressed. Therefore, deformation of the scroll outer peripheral surface 52 formed by the flow path forming member 60 can be suppressed. Furthermore, the flow path forming member 60 is composed of a plurality of small flow path forming pieces 69. Therefore, even if the flow path forming member 60 has an increased weight due to being solid, assembly and disassembly to and from the intermediate wall 152 can be facilitated.

[0054] Furthermore, an outer forming member 70 fixed to the outer casing 11 is disposed between the outer casing 11 and the flow path forming member 60. Therefore, even if the flow path forming member 60 is formed with a minimum thickness required to form the scroll outer peripheral surface 52, the flow path forming member 60 can be supported by the outer casing 11 via the outer forming member 70. Therefore, no matter how the size of the discharge scroll 50 is changed, deformation of the flow path forming member 60 due to the high-pressure fluid flowing into the discharge scroll 50 can be suppressed. As a result, for an existing centrifugal compressor 1, the size of the discharge scroll 50 can be changed while maintaining stable performance by changing the shape of the flow path forming member 60 without remaking the outer casing 11 or the multiple diaphragms 15.

[0055] Furthermore, the outer forming member 70, which has support members 71 facing the flow path forming member 60, is disposed on the outer side Dro in the radial direction Dr relative to the flow path forming member 60, and is formed long in the circumferential direction Dc so as to cover the flow path forming member 60. Therefore, it tends to be larger and heavier than the flow path forming member 60. In contrast, in this embodiment, a space is formed between the outer forming member 70 and the outer casing 11. That is, the outer forming member 70 can be formed to have a hollow shape while supporting the flow path forming member 60 with the support members 71. Therefore, the weight of the outer forming member 70 can be reduced.

[0056] In particular, in this embodiment, the outer forming member 70 is made up of a plurality of small outer forming pieces 79. Therefore, even if the outer forming member 70 is large and heavy, assembly and disassembly work becomes easier.

[0057] Furthermore, a plurality of through holes 73 are formed in the outer forming member 70. Therefore, the through holes 73 connect the space formed between the outer casing 11 and the space in which the flow path forming member 60 is disposed. This makes it possible to suppress the occurrence of a pressure difference between the space formed between the outer casing 11 and the space in which the flow path forming member 60 is disposed. Therefore, deformation of the support member 71 due to the pressure difference can be suppressed. As a result, even if the outer casing 11 is hollow, the flow path forming member 60 can be stably supported.

[0058] Furthermore, when the bundle 30 is inserted into the outer casing 11, the first roller 181 and the second roller 182 continue to contact the inner circumferential surface of the lower part of the outer casing 11. In contrast, the outer forming member 70 has a recess 74 in a region overlapping with the first roller 181 and the second roller 182 in the circumferential direction Dc when viewed from the axial direction Da. The recess 74 is recessed in the radial direction Dr at the same position as the first roller 181 and the second roller 182. Therefore, when the first roller 181 and the second roller 182 move on the outer forming member 70 in the axial direction Da, the recess 74 allows the first roller 181 and the second roller 182 to pass through without contacting the outer forming member 70. Therefore, it is possible to prevent the weight of the bundle 30 from being applied to the outer forming member 70 via the first roller 181 and the second roller 182. This prevents the support member 71 from being deformed.

[0059] (Other embodiments) The above describes in detail the embodiments of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure.

[0060] The centrifugal compressor 1 is not limited to a structure having the outer forming member 70. In other words, the centrifugal compressor 1 may have only the flow path forming member 60 without having the outer forming member 70.

[0061] Furthermore, the flow path forming member 60 and the outer forming member 70 are not limited to a structure in which they are disposed only at the discharge port 112. For example, in the case of the centrifugal compressor 1 of the present embodiment having an intermediate discharge port 114, the flow path forming member 60 and the outer forming member 70 may be disposed at the intermediate discharge port 114 in addition to the discharge port 112.

[0062] Furthermore, the centrifugal compressor 1 is not limited to being a back-to-back type single-shaft multi-stage centrifugal compressor as in this embodiment. The centrifugal compressor 1 may be a straight type single-shaft multi-stage centrifugal compressor in which all of the impellers 22 face in the same direction.

[0063] Furthermore, the flow path forming member 60 and the outer forming member 70 are not limited to having a divided structure made up of a plurality of members, and may be formed from a single member.

[0064] <Additional Notes> The centrifugal compressor 1 according to the embodiment can be understood, for example, as follows.

[0065] (1) A centrifugal compressor 1 according to a first aspect includes a rotating shaft 2 extending in an axial direction Da along which a central axis O extends, and a casing 10 having an inlet 111 formed on a first side Da1 in the axial direction Da and a discharge port 112 formed on a second side Da2 in the axial direction Da, the rotating shaft 2 being disposed within the casing 10 and including an impeller 22 that compresses and discharges a working fluid supplied from the first side Da1 in the axial direction Da to an outer side Dro in a radial direction Dr based on the central axis O, the casing 10 including a diaphragm 15 formed in a cylindrical shape and extending in the axial direction Da so as to cover the rotating shaft 2, an outer casing 11 that extends in the axial direction Da so as to cover the diaphragm 15, a diffuser passage 42 that guides the working fluid discharged from the impeller 22 toward the outer side Dro in the radial direction Dr, and a diffuser passage 43 that guides the working fluid discharged from the impeller 22 toward the outer side Dro in the radial direction Dr. the discharge scroll (50) is connected to the diffuser flow path (42) at the outer side (Dro) in the radial direction (Dr) and extends in a circumferential direction (Dc) around the central axis (O); the rotating shaft (2) and the diaphragm (15) are formed in a cylindrical shape extending in the axial direction (Da), and form a bundle (30) housed in the outer casing (11) at the inner side (Dri) in the radial direction (Dr) in a state where they can be inserted into and removed from the outer casing (11) in the axial direction (Da); and the flow path forming member (60) is formed with an outer diameter smaller than the outer diameter of the diaphragm (15) in the radial direction (Dr), extends in the circumferential direction (Dc), and is fixed to the diaphragm (15) from the axial direction (Da).

[0066] According to this configuration, the flow path forming member 60 is formed as a separate member from the outer casing 11 and the plurality of diaphragms 15. Therefore, by changing the size of the flow path forming member 60, the size of the discharge scroll 50 can be changed without changing the shapes of the outer casing 11 and the plurality of diaphragms 15.

[0067] Furthermore, because the flow path forming member 60 is a member extending in the circumferential direction Dc, the scroll outer peripheral surface 52 also has a shape that extends smoothly in the circumferential direction Dc. Therefore, the scroll outer peripheral surface 52 of the flow path forming member 60 allows the working fluid that has flowed in from the diffuser flow path 42 to flow smoothly to the discharge port 112. This ensures the performance of the scroll flow path.

[0068] In addition, the flow path forming member 60 is formed with an outer diameter smaller than the outer diameter of the bundle 30 in the radial direction Dr, and is fixed to the diaphragm 15 in the axial direction Da. Therefore, no matter how the size of the discharge scroll 50 is changed, the flow path forming member 60 does not protrude outside Dro from the multiple diaphragms 15 in the radial direction Dr. In other words, no matter how the size of the discharge scroll 50 is changed, the flow path forming member 60 does not interfere with the outer casing 11. Therefore, assembly is not hindered when inserting or removing the external casing 11 and the bundle 30. As a result, no matter how the size of the discharge scroll 50 is changed, the impact on assembly of the centrifugal compressor 1 having the bundle 30 can be suppressed.

[0069] (2) The centrifugal compressor 1 according to the second aspect is the centrifugal compressor 1 of (1), wherein the flow path forming member 60 is formed in a solid shape and is composed of a plurality of small flow path forming pieces 69 divided in the circumferential direction Dc.

[0070] According to this configuration, the flow path forming member 60 is formed in a solid shape. Therefore, even if the high-pressure working fluid discharged from the impeller 22 flows into the discharge scroll 50, deformation of the flow path forming member 60 can be suppressed. Therefore, deformation of the scroll outer peripheral surface 52 formed by the flow path forming member 60 can be suppressed. Furthermore, the flow path forming member 60 is composed of a plurality of small flow path forming pieces 69. Therefore, even if the flow path forming member 60 has an increased weight due to being solid, assembly and disassembly of the plurality of diaphragms 15 can be facilitated.

[0071] (3) A centrifugal compressor 1 according to a third aspect is the centrifugal compressor 1 of (1) or (2), wherein the casing 10 further has an outer forming member 70 that is arranged between the outer casing 11 and the flow path forming member 60 and is fixed to the outer casing 11, in a state where the casing 10 is in contact with the flow path forming member 60 on the outer side Dro of the radial direction Dr.

[0072] According to this configuration, even if the flow path forming member 60 is formed with the minimum thickness required to form the scroll outer peripheral surface 52, the flow path forming member 60 can be supported by the outer casing 11 via the outer forming member 70. Therefore, no matter how the size of the discharge scroll 50 is changed, deformation of the flow path forming member 60 due to the high-pressure fluid flowing into the discharge scroll 50 can be suppressed. As a result, for an existing centrifugal compressor 1, the size of the discharge scroll 50 can be changed while maintaining stable performance by changing the shape of the flow path forming member 60 without recreating the outer casing 11 or the multiple diaphragms 15.

[0073] (4) The centrifugal compressor 1 according to the fourth aspect is the centrifugal compressor 1 of (3), wherein the outer forming member 70 has a support member 71 facing the flow path forming member 60, and forms a space between the outer casing 11.

[0074] According to this configuration, the outer forming member 70 can be formed in a hollow shape while supporting the flow path forming member 60 with the support member 71. Therefore, the weight of the outer forming member 70 can be reduced.

[0075] (5) A centrifugal compressor 1 according to a fifth aspect is the centrifugal compressor 1 of (4), wherein the outer forming member 70 has a through-hole 73 that penetrates the support member 71 in the radial direction Dr.

[0076] With this configuration, the through-holes 73 can prevent a pressure difference from occurring between the space formed between the outer casing 11 and the space in which the flow path forming member 60 is disposed. This can prevent the support member 71 from being deformed by the pressure difference. As a result, even if the outer casing 11 is hollow, the flow path forming member 60 can be stably supported.

[0077] (6) A centrifugal compressor 1 according to a sixth aspect is a centrifugal compressor 1 according to any one of (2) to (5), wherein the casing 10 is arranged below the bundle 30 in the vertical direction and further has a roller 18 that contacts the inner circumferential surface of the lower part of the outer casing 11 when the bundle 30 is inserted into the outer casing 11, and the outer forming member 70 has a recess 74 that is recessed in the radial direction Dr at the same position as the roller 18 in the circumferential direction Dc when viewed from the axial direction Da.

[0078] With this configuration, when the rollers 18 move on the outer forming member 70 in the axial direction Da, the recesses 74 allow the rollers 18 to pass through without coming into contact with the outer forming member 70. This prevents the weight of the bundle 30 from being applied to the outer forming member 70 via the rollers 18. This prevents the support member 71 from being deformed. [Explanation of symbols]

[0079] 1...Centrifugal compressor 20A...First compression section 20B...Second compression section O…Central axis 2...Rotation axis 21...Rotating shaft body 22...Impeller 22A, 22B...Impeller group 23...Impeller passage 10...Casing 11...Outer casing 111...Intake port 112…Discharge port 113...Intermediate suction port 114…Intermediate discharge port 15...Diaphragm 151...Diaphragm body 152...Intermediate wall 151A, 151B...Diaphragm body group 40...Casing flow path 41...Inlet channel 42...Diffuser flow path 43...Return flow path 17...Head 171...First casing head 172...Second casing head 30…Bundle 18...Laura 181...First Roller 182...Second roller 50...Discharge scroll 51...Scroll inner surface 52...Scroll outer surface 53...First flow path forming surface 54…Second flow path forming surface 60...flow path forming member 65...volts 69…Small channel forming piece 70...Outer forming member 71...Support member 72...Fixing member 73...Through hole 74...recess 79…Small outer forming piece 31...Thrust bearing 32A, 32B...Journal bearings Da...Axial direction Da1…first side Da2…Second side Dr… radial direction Dro…outside Dri…Inside Dc…circumferential direction

Claims

1. a rotation axis extending in the axial direction of the central axis; a casing having an intake port formed on a first side in the axial direction and an exhaust port formed on a second side in the axial direction, the rotating shaft has an impeller disposed in the casing, which compresses and discharges the working fluid supplied from a first side in the axial direction outward in a radial direction relative to the central axis, The casing comprises: a diaphragm formed in a cylindrical shape extending in the axial direction so as to cover the rotary shaft; an outer casing formed in a cylindrical shape extending in the axial direction so as to cover the diaphragm; a diffuser flow path that guides the working fluid discharged from the impeller toward an outer side in the radial direction; a discharge scroll that guides the working fluid discharged from the impeller to the discharge port; a flow path forming member in the discharge scroll, the flow path forming member being located on the outer side in the radial direction and having a scroll outer peripheral surface facing inward in the radial direction, The discharge scroll is connected to the diffuser passage on the outer side in the radial direction, extending in a circumferential direction around the central axis, the rotating shaft and the diaphragm are formed in a cylindrical shape extending in the axial direction, and form a bundle housed inside the outer casing in the radial direction in a state where they can be inserted and removed in the axial direction; the flow path forming member is formed with an outer diameter smaller than an outer diameter of the bundle in the radial direction, extends in the circumferential direction, and is fixed to the diaphragm in the axial direction.

2. 2. The centrifugal compressor according to claim 1, wherein the flow passage forming member is formed in a solid shape and is configured by a plurality of small flow passage forming pieces divided in the circumferential direction.

3. 3. The centrifugal compressor according to claim 1, wherein the casing further includes an outer forming member that is disposed between the outer casing and the flow path forming member and is fixed to the outer casing in a state of contact with the flow path forming member on the outer side in the radial direction.

4. 4. The centrifugal compressor according to claim 3, wherein the outer forming member has a support member facing the flow path forming member, and forms a space between the outer casing and the support member.

5. The centrifugal compressor according to claim 4 , wherein the outer forming member has a through-hole that passes through the support member in the radial direction.

6. the casing further includes a roller that is disposed below the bundle in the vertical direction and that contacts an inner circumferential surface of the lower part of the outer casing when the bundle is inserted into the outer casing; The centrifugal compressor according to claim 3 , wherein the outer forming member has a recess that is recessed in the radial direction and is located at the same position as the roller in the circumferential direction when viewed from the axial direction.

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