JP2010151032A - Centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To give a velocity component in a circumferential direction to a fluid flow from the circulation flow passage to a diffuser flow passage without providing complicatedly shaped guide vanes, form a low-cost and high-performance circulation flow passage, and expand an operation range. <P>SOLUTION: A centrifugal compressor 10 includes a rotation shaft 3 for being rotatably driven, an impeller 5 fixed to the rotation shaft 3 and for compressing sucked fluid, a diffuser flow passage 7 for guiding the fluid from the impeller 5 to a radial direction of the rotation shaft 3, and a circulation flow passage 9 for returning a part of the fluid flowing into the diffuser flow passage 7 from a downstream position of the diffuser flow passage 7 to an upstream position thereof, as circulation fluid. The circulation flow passage 9 includes a downstream opening 9a that opens to the diffuser flow passage 7, and an upstream opening 9b that opens to the diffuser flow passage 7. The circulation flow passage 9 extends toward the upstream opening 9b from an intermediate part thereof, and in a direction inclined toward, with respect to an axial direction of the rotation shaft 3, the circumferential direction of the rotation shaft 3. Therefore, a velocity of the circulating fluid flowing out from the upstream opening 9b to the diffuser flow passage 7 has the velocity component in the circumferential direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a centrifugal compressor.

  The centrifugal compressor includes a rotary shaft that is rotationally driven, an impeller that is fixed to the rotary shaft and compresses suction fluid, and a diffuser flow path that guides the fluid from the impeller in the radial direction of the rotary shaft.

  The fluid flow rate delivered from the impeller to the diffuser flow path needs to be within a predetermined stable flow rate range. When the fluid flow rate is lower than the stable flow rate range, a surge phenomenon or a back flow of the fluid occurs. The surge phenomenon is a phenomenon in which a large vibration is generated due to unstable fluid pressure and flow.

  A technique for expanding the stable flow rate range to the low flow rate side while suppressing the surge phenomenon and the reverse flow is disclosed in Patent Document 1 below.

In Patent Document 1, a circulation channel 23 is provided as shown in FIG. As a result, the fluid flowing through the diffuser flow path 25 enters the circulation flow path 23 from the downstream opening 23 a and is returned to the diffuser flow path 25 from the upstream opening 23 b. Therefore, the apparent fluid flow rate in the diffuser flow path 25 increases. As a result, surge phenomenon and backflow are suppressed. In FIG. 6, the circulation flow path 23 is formed by a lid member 29 supported by the casing 21 via a support member 27 and the casing 21. Reference numeral 31 denotes an impeller, reference numeral 31a denotes a blade of the impeller 31, reference numeral 33 denotes a rotating shaft, and reference numeral 35 denotes a suction passage.
Moreover, in another structure of patent document 1, the above-mentioned support member 27 is made into the guide blade. Thereby, the fluid returning from the circulation flow path 23 to the diffuser flow path 25 has a velocity component in the circumferential direction of the rotating shaft 33 and becomes a swirl flow. As a result, the swirl angle of the fluid from the circulation channel 23 and the fluid in the diffuser channel 25 are substantially the same, preventing the occurrence of turbulent flow and enabling smooth pressure increase.

Japanese Patent Laid-Open No. 2005-240680

  As described above, when the guide vanes are provided in the circulation flow path and the fluid returning from the circulation flow path to the diffuser flow path is a swirling flow, it is necessary to design and manufacture a guide blade having a complicated shape. . Therefore, the cost increases accordingly.

  Accordingly, an object of the present invention is to provide a circumferential velocity component to the fluid flow from the circulation flow path to the diffuser flow path without providing complicated-shaped guide vanes, and to achieve a low-cost and high-performance circulation flow. It is to form a path and expand the operating range.

In order to achieve the above object, according to the present invention, a rotary shaft that is rotationally driven, an impeller that is fixed to the rotary shaft and compresses suction fluid, and a diffuser that guides fluid from the impeller in the radial direction of the rotary shaft A centrifugal compressor having a flow path and a circulation flow path for returning a part of the fluid flowing through the diffuser flow path as a circulating fluid from a downstream position to an upstream position in the diffuser flow path,
The circulation flow path has a downstream opening that opens to the diffuser flow path at the downstream position, and an upstream opening that opens to the diffuser flow path at the upstream position,
The circulation channel extends from the intermediate portion toward the upstream opening in a direction inclined in the circumferential direction of the rotation shaft with respect to the axial direction of the rotation shaft. A centrifugal compressor is provided in which the circulating fluid velocity flowing into the diffuser flow path has the circumferential velocity component.

In the present invention described above, the circulation flow path extends from the intermediate portion toward the upstream opening in a direction inclined in the circumferential direction of the rotation shaft with respect to the axial direction of the rotation shaft. Since the circulating fluid velocity flowing out from the upstream opening into the diffuser flow path has the circumferential velocity component, it is apparent due to the fluid from the impeller having the circumferential velocity component and the circulating fluid from the downstream opening. The upper flow rate can be increased, and the stable flow rate range of the centrifugal compressor can be further expanded to the low flow rate side. Further, in the present invention, the circulation flow path is directed from the intermediate part toward the upstream opening. Since it extends in the direction inclined in the circumferential direction of the rotating shaft with respect to the axial direction of the rotating shaft, a guide vane having a plurality of shapes for giving a speed component in the circumferential direction can be reduced without providing the circulation flow path. High in cost A high-performance circulation channel can be realized.

According to a preferred embodiment of the present invention, there is provided a diffuser flow path partition member that partitions at least a part of the diffuser flow path, and the diffuser flow path partition member has an upstream through hole and a downstream through hole. And
The circulation channel includes the upstream through-hole having the upstream opening, the downstream through-hole having the downstream opening, and a fluid pipe connected to the upstream through-hole and the downstream through-hole, Consisting of
The fluid pipe extends from the intermediate portion toward the upstream opening in a direction inclined in the circumferential direction of the rotary shaft with respect to the axial direction of the rotary shaft.

  Thus, the circulation channel is connected to the upstream through hole having the upstream opening, the downstream through hole having the downstream opening, and the upstream through hole and the downstream through hole. A fluid pipe, and the fluid pipe extends from the intermediate portion toward the upstream opening in a direction inclined in the circumferential direction of the rotary shaft with respect to the axial direction of the rotary shaft. Without designing the guide vanes, the circumferential velocity component can be given to the circulating fluid only by adjusting the direction in which the fluid pipe extends.

  Preferably, the upstream side through-hole to which one end of the fluid pipe is connected is shifted from the downstream through-hole to which the other end of the fluid pipe is connected in the circumferential direction.

  Thus, the upstream through hole to which the fluid pipe is connected is located in the circumferential direction so as to be circulated from the downstream through hole to which the fluid pipe is connected. It can be efficiently applied to the fluid.

  According to a preferred embodiment of the present invention, a plurality of the upstream through holes and the downstream through holes are provided at intervals in the circumferential direction, and one end of the fluid pipe has a plurality of the upstream through holes. The hole can be attached to and detached from any one of the holes, and the other end can be attached to and detached from any of the plurality of downstream through holes.

  Thus, since the fluid pipe is detachable from the upstream through hole and the downstream through hole, the fluid pipe can be rearranged by selecting the upstream through hole and the downstream through hole to be attached. . Therefore, the circulation channel can be adjusted.

  According to a preferred embodiment of the present invention, a plurality of circulation channels are provided in the circumferential direction.

  As described above, a plurality of the circulation channels described above can be provided in the circumferential direction. These circulation flow paths may be independent from each other, or may be in communication with each other at an intermediate portion.

  According to the present invention described above, a low-cost and high-performance circulation flow path can be provided to the fluid flow from the circulation flow path to the diffuser flow path without providing a complicated-shaped guide vane. Can be formed.

  The best mode for carrying out the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a cross-sectional view showing a centrifugal compressor 10 according to an embodiment of the present invention. As shown in FIG. 1, the centrifugal compressor 10 according to the present embodiment includes a rotating shaft 3, an impeller 5, a diffuser flow path 7, a circulation flow path 9, and the like.

  For example, the rotary shaft 3 is coupled to a turbine impeller (not shown) and may be rotationally driven by the rotation of the turbine impeller, may be rotationally driven by an electric motor (not shown), or may be rotationally driven by other means. Good.

  The impeller 5 is fixed to the rotating shaft 3 and compresses the fluid from the fluid suction passage 11 and discharges it in the radial direction (hereinafter simply referred to as the radial direction). In this example, the fluid is a gas, but may be a liquid. Reference numeral 5 a denotes a blade of the impeller 5. A plurality of blades 5a are provided in the circumferential direction of the rotating shaft 3 (hereinafter simply referred to as the circumferential direction).

  The diffuser flow path 7 guides the fluid from the impeller 5 in the radial direction of the rotary shaft 3. The diffuser flow path 7 has a donut shape in which the impeller 5 is located at the center when viewed from the axial direction of the rotating shaft 3 (hereinafter simply referred to as the axial direction).

  The circulation channel 9 is a channel that returns a part of the fluid flowing through the diffuser channel 7 as a circulating fluid from the downstream position to the upstream position in the diffuser channel 7.

  The circulation channel 9 according to the present embodiment will be described in detail.

  2 is a view taken along the line II-II in FIG. FIG. 3 shows one fluid pipe 15 (described later) and its periphery as seen from the radial direction in FIG. 3 is a view taken along the line III-III in FIG. 2 and shows only one of the plurality of fluid pipes 15 in FIG.

  The circulation flow path 9 has a downstream opening 9 a that opens to the diffuser flow path 7 at the downstream position, and an upstream opening 9 b that opens to the diffuser flow path 7 at the upstream position. The circulation flow path 9 extends from the intermediate portion toward the upstream opening 9b in a direction inclined in the circumferential direction of the rotation shaft 3 with respect to the axial direction of the rotation shaft 3, and thereby the diffuser from the upstream opening 9b. The circulating fluid velocity that flows out into the flow path 7 has a velocity component in the circumferential direction. The circumferential direction is a swirl direction of fluid discharged from the impeller 5 to the diffuser flow path 7.

A diffuser flow path partition member 13 that partitions at least a part of the diffuser flow path 7 is provided. In the example of FIG. 1, the diffuser flow path partition member 13 is a casing 13. The diffuser flow path partition member 13 has an upstream through hole 13b and a downstream through hole 13a. The upstream side through hole 13b and the downstream side through hole 13a penetrate the diffuser flow path partition member 13 in the axial direction or in the direction having the axial component. In the example of FIG. 1, the diffuser flow path 7 is defined by a casing 13 and a seal plate member 14 that is coupled to the casing 13 and has an annular shape when viewed from the axial direction.
The circulation channel 9 includes an upstream through hole 13b having an upstream opening 9b, a downstream through hole 13a having a downstream opening 9a, and a fluid pipe connected to the upstream through hole 13b and the downstream through hole 13a. 15. The fluid pipe 15 extends from the intermediate portion toward the upstream opening 9b in a direction inclined in the circumferential direction of the rotary shaft 3 with respect to the axial direction of the rotary shaft 3, and thereby the diffuser flow from the upstream opening 9b. The speed of the circulating fluid flowing out into the path 7 has a circumferential speed component. The fluid pipe 15 may be made of metal or other material such as resin.

Preferably, the upstream side through-hole 13b to which the fluid pipe 15 is connected is shifted from the downstream side through-hole 13a to which the fluid pipe 15 is connected in the circumferential direction. That is, one end of the fluid pipe 15 is connected to the downstream side through-hole 13a from the side opposite to the downstream side opening 9a, and the other end is connected to the upstream side through-hole 13b shifted in the circumferential direction from the downstream side through-hole 13a. , And connected from the opposite side to the upstream opening 9b.
The connection between the fluid pipe 15 and the upstream side through hole 13b and the downstream side through hole 13a may be made with an adhesive, or flange portions are provided at the one end and the other end of the fluid pipe 15, and these flange portions are provided. May be fixed to the diffuser flow path partition member 13 with a screw or the like, or may be made by other appropriate means.

  In FIG. 3, the upstream side through-hole 13 b is formed such that a space is provided on the straight virtual extension (shown by a broken line) of the circulation channel 9. With this configuration, the fluid flowing into the upstream through-hole 13b from the circulation flow path 9 has a circumferential speed component, and the upstream through-hole 13b enters the diffuser flow path 7 while maintaining this speed component. Fluid flows out. However, the shape of the upstream through-hole 13b is not limited to the shape shown in FIG. 3 as long as the virtual extension portion of the circulation flow path 9 is a space, and the shape shown in FIG. The shape shown in FIG. 4 or the shape shown in FIG. FIG. 4 corresponds to FIG. 3 and 4, the upstream side through-hole 13b and the downstream side through-hole 13a are seen through and shown by solid lines.

Preferably, a plurality of the upstream through holes 13b and the downstream through holes 13a are provided at intervals in the circumferential direction, and one end of the fluid pipe 15 is formed at any one of the plurality of upstream through holes 13b. The other end can be attached to and detached from any of the plurality of downstream through holes 13a.
In this case, the connection between the fluid pipe 15 and the upstream side through hole 13b and the downstream side through hole 13a may be made by detachably fixing the flange portion to the diffuser flow path partition member 13 with a screw or the like. It may be made detachable using a fitting, or may be made by other appropriate means.
Note that only some of the plurality of upstream through holes 13b and the plurality of downstream through holes 13a may be used. In this case, the upstream side through-hole 13b and the downstream side through-hole 13a that are not used (that is, the fluid pipe 15 is not connected) may be filled with clay, silicon, or the like, or fitting may be used. When fitting is used, the fitting mechanism on the side to be attached to the upstream side through hole 13b and the downstream side through hole 13a is made solid so that there is no hollow portion. It may be closed.

  According to the centrifugal compressor 10 according to the embodiment of the present invention described above, the following effects can be obtained.

(1) The circulation flow path 9 extends from the intermediate portion toward the upstream opening 9b in a direction inclined in the circumferential direction of the rotation shaft 3 with respect to the axial direction of the rotation shaft 3, and thereby the upstream opening. Since the circulating fluid velocity that flows out from 9b into the diffuser flow path 7 has a circumferential velocity component, the apparent flow rate depends on the fluid from the impeller 5 having the circumferential velocity component and the circulating fluid from the downstream opening 9a. As a result, the stable flow rate range of the centrifugal compressor 10 can be further expanded to the low flow rate side.

(2) Since the circulation channel 9 extends from the intermediate portion toward the upstream opening 9b in a direction inclined in the circumferential direction of the rotary shaft 3 with respect to the axial direction of the rotary shaft 3, the circumferential speed is increased. The high-performance circulation flow path 9 can be realized at low cost without providing the circulation flow path 9 with guide vanes having a plurality of shapes for providing components.

(3) The circulation channel 9 is connected to the upstream through hole 13b having the upstream opening 9b, the downstream through hole 13a having the downstream opening 9a, and the upstream through hole 13b and the downstream through hole 13a. The fluid pipe 15 extends from the intermediate portion toward the upstream opening 9b in a direction inclined in the circumferential direction of the rotary shaft 3 with respect to the axial direction of the rotary shaft 3. Therefore, the circumferential velocity component can be given to the circulating fluid only by adjusting the direction in which the fluid pipe 15 extends without designing the guide vanes.

(4) Since the upstream opening 9b to which the fluid pipe 15 is connected is located in the circumferential direction so as to be shifted from the downstream opening 9a to which the same fluid pipe 15 is connected, the circumferential velocity component is efficiently used as the circulating fluid. Can be given well. That is, the circumferential direction from the downstream opening 9a toward the upstream opening 9b is the direction of the fluid turning from the impeller 5 (the direction of rotation of the rotating shaft 3), and thus the velocity component in this direction of rotation is efficiently imparted to the circulating fluid. can do.

(5) Since the fluid pipe 15 can be attached to and detached from the upstream side through hole 13b and the downstream side through hole 13a, the fluid pipe 15 can be rearranged by selecting the upstream side through hole 13b and the downstream side through hole 13a to be attached. it can. Therefore, the circulation channel 9 can be adjusted.

  The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

  In the above-described embodiment, as shown in FIG. 2, the downstream through hole 13a and the upstream through hole 13b are formed at two locations in the radial direction (that is, the downstream position and the upstream position). According to the invention, through-holes are formed at three or more locations in the radial direction, and among these through-holes, a through-hole located between the through-hole 13a located at the most downstream side and the through-hole 13b located at the most upstream side. Can be used as the downstream through hole 13a or the upstream through hole 13b. For example, as shown in FIG. 5 corresponding to FIG. 2, through holes 13a, 13b, and 13c are formed at three locations in the radial direction, and the intermediate through hole 13c can be used as the downstream through hole 13a or the upstream through hole 13b. . In this case, the through holes 13a, 13b, and 13c to be used are arbitrarily selected, and both ends of the fluid pipe 15 are connected to the selected downstream through hole 13a or 13c and the upstream through hole 13b or 13c, respectively. Also in this case, it is preferable to provide a plurality of fluid pipes 15 in the circumferential direction. Further, the through holes 13a, 13b, and 13c that are not used are filled with clay, silicon, or the like as described above to close the through holes 13a and 13b. Other configurations may be the same as those in the above-described embodiment.

  Instead of providing the fluid pipe 15, the circulation flow path 9 of the present invention may be formed inside a member that defines the diffuser flow path 7 such as the casing 13. In this case, other configurations may be the same as those in the above-described embodiment.

It is sectional drawing which shows the principal part of the centrifugal compressor by embodiment of this invention. It is the II-II arrow directional view of FIG. It is the III-III arrow directional view of FIG. It is a figure which shows the other shape of an upstream through-hole. 3 shows another embodiment of the present invention. 1 is a cross-sectional view showing a centrifugal compressor described in Patent Document 1. FIG.

Explanation of symbols

3 Rotating shaft, 5 impeller, 5a impeller blades, 7 diffuser flow path, 9 circulation flow path, 9a downstream opening, 9b upstream opening, 10 centrifugal compressor, 11 fluid suction flow path, 13 casing (diffuser flow path section) Member), 13a downstream through hole, 13b upstream through hole, 13c intermediate through hole, 14 seal plate member, 15 fluid pipe,

Claims (5)

A rotary shaft that is driven to rotate, an impeller that is fixed to the rotary shaft and compresses suction fluid, a diffuser flow path that guides the fluid from the impeller in the radial direction of the rotary shaft, and a fluid that flows through the diffuser flow path A circulation flow path that returns a part of the diffuser flow path as a circulating fluid from a downstream position to an upstream position in the diffuser flow path,
The circulation flow path has a downstream opening that opens to the diffuser flow path at the downstream position, and an upstream opening that opens to the diffuser flow path at the upstream position,
The circulation channel extends from the intermediate portion toward the upstream opening in a direction inclined in the circumferential direction of the rotation shaft with respect to the axial direction of the rotation shaft. A centrifugal compressor characterized in that a circulating fluid velocity flowing into the diffuser flow path has the circumferential velocity component. A diffuser flow path partition member that partitions at least a part of the diffuser flow path is provided, and the diffuser flow path partition member has an upstream through hole and a downstream through hole,
The circulation channel includes the upstream through-hole having the upstream opening, the downstream through-hole having the downstream opening, and a fluid pipe connected to the upstream through-hole and the downstream through-hole, Consisting of
2. The fluid pipe according to claim 1, wherein the fluid pipe extends in a direction inclined in a circumferential direction of the rotation shaft with respect to an axial direction of the rotation shaft from an intermediate portion thereof toward the upstream side opening. Centrifugal compressor.   The upstream through-hole to which one end of the fluid pipe is connected is shifted from the downstream through-hole to which the other end of the fluid pipe is connected in the circumferential direction. The centrifugal compressor according to 1 or 2.   A plurality of the upstream through holes and the downstream through holes are provided at intervals in the circumferential direction, and one end of the fluid pipe can be attached to or detached from any of the plurality of upstream through holes. The other end of the centrifugal compressor according to any one of claims 1 to 3, wherein the other end can be attached to and detached from any of the plurality of downstream through holes.   The centrifugal compressor according to any one of claims 1 to 4, wherein a plurality of the circulation channels are provided in the circumferential direction.

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