JP2014074389A - Centrifugal compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal compressor in which a pressure recovery factor in a diffuser is improved and deterioration of processing accuracy and assembling accuracy of a guide blade is prevented.SOLUTION: A centrifugal compressor includes a radial impeller, and a diffuser 7. The diffuser 7 includes: a first annular flow channel 7a provided so as to surround the radial impeller, and formed between a pair of planar flow channel wall surfaces 7a1 and 7a2 facing in parallel each other; a second annular flow channel 7b disposed in the outside of the first annular flow channel 7a, and formed between a pair of planar flow channel wall surfaces 7b1 and 7b2 facing in parallel each other at an interval wider than that of the flow channel wall surfaces 7a1 and 7a2 forming the first annular flow channel 7a; a first guide blade 7d disposed in the first annular flow channel 7a; and a second guide blade 7e disposed in the second annular flow channel 7b and having a blade height larger than that of the first guide blade 7d.

Description

  The present invention relates to a centrifugal compressor.

  In a centrifugal compressor, velocity energy is imparted to a fluid such as air by a radial impeller, and the fluid to which the velocity energy is imparted is decelerated by a diffuser and pressurized to compress the fluid.

  In such a centrifugal compressor, guide vanes for guiding fluid to the diffuser are installed. This guide vane directs the fluid sent in the radial direction of the radial impeller in the flow direction of the scroll flow path so that the fluid sent from the radial impeller flows smoothly into the scroll flow path provided outside the diffuser. I will guide you.

  By the way, for example, Patent Document 1 discloses that the pressure recovery rate is increased by expanding the height of the flow path of the diffuser as it goes outward in the radial direction of the radial impeller, and even if the flow path length of the diffuser is short, the fluid can reach a desired pressure. A centrifugal compressor capable of compressing is disclosed. According to such a centrifugal compressor, the outer size of the centrifugal compressor can be reduced by reducing the flow path length of the diffuser, and the centrifugal compressor can be reduced in size and weight.

  In such a centrifugal compressor disclosed in Patent Document 1, since the flow passage wall surface of the diffuser becomes a tapered surface, the abutting surface with the flow passage wall surface of the guide blade installed in the diffuser is also a tapered surface. .

JP 58-183899 A

  However, if the abutting surface of the guide blade is a tapered surface, the shape of the guide blade is complicated, so it is difficult to maintain the processing accuracy, the yield of the guide blade is deteriorated, and the manufacturing cost of the centrifugal compressor is increased. . Further, if the abutting surface of the guide vanes is a tapered surface, the assembly accuracy of the guide vanes is also deteriorated, leading to a decrease in the fluid guiding function.

  The present invention has been made in view of the above-described problems, and in a centrifugal compressor, it is possible to increase the pressure recovery rate in the diffuser, and to prevent deterioration in the processing accuracy and assembly accuracy of the guide vanes. For the purpose.

  The present invention adopts the following configuration as means for solving the above-described problems.

  A first aspect of the present invention is a centrifugal compressor comprising a radial impeller that applies velocity energy to a fluid and sends the fluid radially, and a diffuser that decelerates and pressurizes the fluid sent from the radial impeller. Is provided to surround the radial impeller, and is provided between a pair of flat channel wall surfaces facing each other in parallel, provided outside the first annular channel, and A second annular channel formed between a pair of planar channel walls facing each other in parallel with a wider interval than the channel wall surface forming the first annular channel, and the first annular channel installed in the first annular channel A configuration is adopted in which a first guide vane and a second guide vane installed in the second annular flow path and having a blade height larger than that of the first guide vane are employed.

  According to a second invention, in the first invention, the diffuser is provided between the first annular channel and the second annular channel, and a channel wall surface forming the first annular channel; A configuration is adopted in which an intermediate channel having an inclined surface connecting the channel wall surface forming the second annular channel is provided.

  According to a third invention, in the first or second invention, a configuration is adopted in which the second guide vanes are installed on an extension line of the fluid guiding direction by the first guide vanes.

  In the present invention, the diffuser is divided into a first annular flow path on the radial impeller side and a second annular flow path on the outside thereof, and the first annular flow path and the second annular flow path face each other in parallel. Are formed between the flow path wall surfaces. Here, the channel wall surfaces forming the second annular channel are spaced apart by a wider interval than the channel wall surfaces forming the first annular channel. That is, the channel height of the second annular channel is set larger than the channel height of the first annular channel. For this reason, in the diffuser, when moving from the first annular flow path to the second annular flow path, the spatial volume is suddenly expanded in the second annular flow path, and the fluid velocity is rapidly decreased to increase the pressure. Therefore, the pressure recovery rate of the diffuser can be increased.

  Furthermore, in this invention, the 1st guide vane installed in a 1st annular flow path and the 2nd guide vane installed in a 2nd annular flow path are provided. For this reason, the fluid flowing through the diffuser is guided by the first guide blade and the second guide blade. That is, in the present invention, the fluid sent out from the radial impeller is guided in almost the entire region from the inlet to the outlet of the diffuser. Therefore, in the present invention, the fluid can be reliably guided in a desired flow direction (for example, the flow direction in the scroll flow path), and the pressure loss can be reduced.

  Further, in the present invention, the first guide vane as described above is installed in the first annular flow path whose flow path wall faces are parallel to each other. Further, the second guide vane is installed in a second annular flow channel having flow channel wall surfaces facing each other in parallel. For this reason, both the abutting surfaces of the first guide vane and the second guide vane with the flow path wall surface are not tapered surfaces but flat surfaces. Therefore, according to the present invention, it is possible to prevent deterioration of the processing accuracy and assembly accuracy of the guide vanes.

(A) is a longitudinal cross-sectional view which shows schematic structure of the centrifugal compressor which concerns on one Embodiment of this invention, (b) is a principal part expansion containing the diffuser with which the centrifugal compressor which concerns on one Embodiment of this invention is equipped. FIG. It is the figure which showed the 1st guide vane with which the centrifugal compressor which concerns on one Embodiment of this invention is equipped, the 2nd guide vane, and a part of housing, and is the figure seen from the right side of Fig.1 (a).

  Hereinafter, an embodiment of a centrifugal compressor according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size. Moreover, in the following description, the example applied to the centrifugal compressor which produces | generates compressed air as a centrifugal compressor which concerns on this invention is demonstrated.

  Fig.1 (a) is a longitudinal cross-sectional view which shows schematic structure of the centrifugal compressor 1 of this embodiment, FIG.1 (b) is a principal part expansion containing the diffuser 7 with which the centrifugal compressor 1 of this embodiment is provided. FIG. As shown in FIG. 1A, the centrifugal compressor 1 of the present embodiment includes a radial impeller 2, a shaft 3, a seal plate 4, a housing 5, bolts 6, and a diffuser 7.

  The radial impeller 2 includes a plurality of blades 2b that are fixed to the base 2a. The radial impeller 2 is rotationally driven, thereby giving velocity energy to the air X (fluid) sucked from the axial direction and sending it out in the radial direction. The shaft 3 is fixed to the center of the radial impeller 2 when viewed from the air X intake direction of the radial impeller 2, and rotational power generated by a drive source (not shown) (motor, turbine, etc.) is supplied to the radial impeller 2. introduce.

  The seal plate 4 is disposed so as to face the back surface of the radial impeller 2, and a through hole for inserting the shaft 3 is provided at the center. The housing 5 is a casing that covers the radial impeller 2 from the air X suction side by being fastened to the seal plate 4 with bolts 6. As shown in FIG. 1 (a), the housing 5 has a suction port 5a for sucking air X, a discharge port 5b for discharging air X, and a discharge port 5b for discharging air X sent from the radial impeller 2. And a scroll flow path 5c that leads to The scroll channel 5c is formed outside the radial impeller 2 so as to surround the radial impeller 2 when viewed from the air X suction direction, and the radial impeller 2 is centered when viewed from the same direction. Air X is guided in the circumferential direction. That is, the flow direction of the air X in the scroll flow path 5 c is set to the circumferential direction around the rotation axis of the radial impeller 2. The bolts 6 fasten the seal plate 4 and the housing 5, and a plurality of bolts 6 are discretely provided in the circumferential direction around the rotational axis of the radial impeller 2.

  The diffuser 7 is provided between the radial impeller 2 and the scroll channel 5c. As shown in FIG. 1B, the first annular channel 7a, the second annular channel 7b, and the intermediate channel 7c, a first guide vane 7d, and a second guide vane 7e.

  The first annular channel 7 a is an annular channel that is provided closer to the radial impeller 2 than the second annular channel 7 b and surrounds the radial impeller 2. As shown in FIG. 1B, the first annular channel 7a is formed between a pair of channel wall surfaces 7a1 and 7a2 facing each other in parallel. The channel wall surface 7a1 is a flat wall surface formed of a part of the surface of the seal plate 4. Further, the flow path wall surface 7 a 2 is a flat wall surface formed of a part of the surface of the housing 5.

  The second annular channel 7b is an annular channel that is provided outside the first annular channel 7a and surrounds the first annular channel 7a via the intermediate channel 7c. As shown in FIG. 1B, the second annular channel 7b is formed between a pair of channel wall surfaces 7b1 and 7b2 facing each other in parallel. The flow path wall surface 7 b 1 is a flat wall surface formed of a part of the surface of the seal plate 4. Further, the flow path wall surface 7 b 2 is a flat wall surface formed of a part of the surface of the housing 5.

  As shown in FIG. 1B, the channel wall surface 7b1 and the channel wall surface 7b2 forming the second annular channel 7b are formed by the channel wall surface 7a1 and the channel wall surface 7a2 forming the first annular channel 7a. Are confronted in parallel at wide intervals. For this reason, the channel height H2 of the second annular channel 7b (the axial size of the radial impeller 2) is greater than the channel height H1 of the first annular channel 7a.

  The intermediate flow path 7c is a flow path that connects the first annular flow path 7a and the second annular flow path 7b. As shown in FIG. 1B, the intermediate flow path 7 c is composed of a part of the surface of the seal plate 4, and is a taper composed of a flow path wall surface 7 c 1 that is a flat wall surface and a part of the surface of the housing 5. It is formed between the flow path wall surface 7c2 which is a planar wall surface. The tapered channel wall surface 7c2 is an inclined surface with respect to the channel wall surface 7a1 forming the first annular channel 7a and the channel wall surface 7b1 forming the second annular channel 7b. The channel wall surface 7b1 is connected.

  The first guide vane 7d is provided in the first annular flow path 7a. The first guide vane 7d has a vane height H3 having the same size as the channel height H1 of the first annular channel 7a, and both end surfaces of the channel wall surface forming the first annular channel 7a. It is a butt | matching surface with (flow-path wall surface 7a1 and flow-path wall surface 7a2). For example, the first guide vane 7d includes a pin (not shown) protruding from both end faces, and this pin is inserted into a fitting hole formed in the flow path wall (the seal plate 4 and the housing 5 in this embodiment). It is positioned and supported by being inserted.

  FIG. 2 is a diagram showing a part of the first guide vane 7d, the second guide vane 7e, and the housing 5, as viewed from the right side of FIG. 1 (a). As shown in this figure, the first guide vane 7d is arranged so that the leading edge faces the radial impeller 2 and the trailing edge faces the downstream side in the flow direction of the scroll flow path 5c. The sent out air X is guided toward the flow direction of the scroll flow path 5c. As shown in FIG. 2, a plurality of such first guide vanes 7d are installed in the first annular flow path 7a, and are arranged in an annular shape with the radial impeller 2 as the center.

  As shown in FIG. 1B, the second guide vane 7e is provided in the second annular flow path 7b. The second guide vane 7e has a vane height H4 having the same size as the channel height H2 of the second annular channel 7b, and both end surfaces of the channel wall surface forming the second annular channel 7b. It is a butt | matching surface with (flow-path wall surface 7b1 and flow-path wall surface 7b2). The second guide vane 7e has a blade height larger than that of the first guide vane 7d. For example, the second guide vane includes a pin (not shown) protruding from both end faces, and this pin is inserted into a fitting hole formed in the flow path wall (the seal plate 4 and the housing 5 in this embodiment). Is positioned and supported.

  As shown in FIG. 2, the second guide vane 7e is arranged such that the leading edge faces the first guiding vane 7d and the trailing edge faces the downstream side in the flow direction of the scroll flow path 5c. The air X guided by the guide vanes 7d is continuously guided in the flow direction of the scroll flow path 5c. As shown in FIG. 2, a plurality of such second guide vanes 7e are installed in the second annular flow path 7b, and are arranged in an annular shape with the radial impeller 2 as the center. Further, the same number of second guide vanes 7e as the first guide vanes 7d are installed, and are arranged on an extension line in a direction from the front edge side to the rear edge side of the first guide vane 7d. That is, the second guide vane 7e is installed on the extended line of the air guide direction of the first guide vane 7d, and can guide the air X without disturbing the flow arranged by the first guide vane 7d.

  In the centrifugal compressor 1 of the present embodiment configured as described above, the rotational power is transmitted to the radial impeller 2 through the shaft 3, and when the radial impeller 2 is driven to rotate, air is introduced into the housing 5 from the suction port 5a. X flows in. The air X flowing in from the suction port 5a is given velocity energy by the radial impeller 2 and is sent out in the radial direction of the radial impeller 2. The air X sent out from the radial impeller 2 in this way is increased in pressure by being decelerated by the diffuser 7, and is discharged as compressed air from the discharge port 5b through the scroll flow path 5c.

  Here, in the centrifugal compressor 1 of this embodiment, in the diffuser 7, the flow path height H4 of the second annular flow path 7b is larger than the flow path height H3 of the first annular flow path 7a. For this reason, compared with the case where the flow path height of the 2nd annular flow path 7b is the same as the 1st annular flow path 7a, space volume increases rapidly in the 2nd annular flow path 7b, and the air X drastically increases. Boosted. Further, in the diffuser 7, the air X is guided toward the flow direction of the scroll flow path 5c by the first guide vane 7d and the second guide vane 7e.

  The operation and effect of the centrifugal compressor 1 of the present embodiment as described above will be described. In the centrifugal compressor 1 of the present embodiment, the diffuser 7 is divided into a first annular passage 7a on the radial impeller 2 side and a second annular passage 7b on the outer side, and the first annular passage 7a and the second annular passage 7b are divided. The annular channel 7b is formed between a pair of channel walls facing each other in parallel. Here, the channel wall surfaces (the channel wall surface 7b1 and the channel wall surface 7b2) forming the second annular channel 7b are the same as the channel wall surfaces (the channel wall surface 7a1 and the channel wall surface) forming the first annular channel 7a. 7a2) spaced apart by a wider distance than each other. That is, the channel height H4 of the second annular channel 7b is set to be greater than the channel height H3 of the first annular channel 7a. For this reason, in the diffuser 7, when it goes to the 2nd annular flow path 7b from the 1st annular flow path 7a, the space volume expands rapidly in the 2nd annular flow path 7b, and the speed | rate of the air X falls rapidly and pressure | voltage rises Is done. Therefore, the pressure recovery rate of the diffuser 7 can be increased.

  Furthermore, the centrifugal compressor 1 of the present embodiment includes a first guide vane 7d installed in the first annular channel 7a and a second guide vane 7e installed in the second annular channel 7b. For this reason, the air X flowing through the diffuser 7 is guided by the first guide blade 7d and the second guide blade 7e. That is, in the centrifugal compressor 1 of the present embodiment, the air X sent out from the radial impeller 2 is guided in almost the entire region from the inlet to the outlet of the diffuser 7. Therefore, in the centrifugal compressor 1 of this embodiment, the air X can be reliably guided in a desired flow direction (flow direction in the scroll flow path 5c), and pressure loss can be reduced.

  Further, in the centrifugal compressor 1 of the present embodiment, the first guide blade 7d as described above is installed in the first annular flow path 7a in which the planar flow path wall surface 7a1 and the flow path wall surface 7a2 are opposed to each other. . Further, the second guide vane 7e is installed in the second annular channel 7b where the planar channel wall surface 7b1 and the channel wall surface 7b2 face each other. For this reason, both the abutting surfaces of the first guide vane 7d and the second guide vane 7e with the flow passage wall surface are not tapered surfaces but flat surfaces. Therefore, in the centrifugal compressor 1 of the present embodiment, the shape of the abutting surfaces of the first guide blade 7d and the second guide blade 7e is a simple flat surface, which prevents deterioration of the processing accuracy and assembly accuracy of the guide blade. It becomes possible.

  Further, in the centrifugal compressor 1 of the present embodiment, the diffuser 7 is provided between the first annular channel 7a and the second annular channel 7b, and the channel wall surface 7a2 that forms the first annular channel 7a; An intermediate channel 7c having an inclined surface (channel wall surface 7c2) connecting the channel wall surface 7b2 forming the second annular channel 7b is provided. For this reason, it can prevent that a big level | step difference arises in the boundary of the flow-path wall surface 7a2 which forms the 1st annular flow path 7a, and the flow-path wall surface 7b2 which forms the 2nd annular flow path 7b. Therefore, it is possible to prevent the air X from being separated from the wall surface of the flow path and to prevent the pressure loss from increasing.

  Further, in the centrifugal compressor 1 of the present embodiment, the second guide blade 7e is installed on an extension line in the air X guiding direction by the first guide blade 7d. For this reason, in the second guide vane 7e, the air X can be guided in the same direction as the direction guided by the first guide vane 7d, and the flow direction of the air X does not change greatly locally. Therefore, according to the centrifugal compressor 1 of the present embodiment, the air X can be guided without disturbing the flow arranged by the first guide vanes 7d.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention.

  For example, in the above embodiment, a centrifugal compressor that generates compressed air has been described. However, the present invention is not limited to this, and can be applied to a centrifugal compressor that compresses another fluid.

  Moreover, in the said embodiment, the structure which installs the same number of 1st guide vanes 7d and 2nd guide vanes 7e was demonstrated. However, the present invention is not limited to this, and the number of the first guide vanes 7d and the second guide vanes 7e may be set differently. For example, the first guide vane 7d may be smaller than the second guide vane 7e to reduce the pressure loss in the first annular flow path 7a.

  In the above embodiment, the channel wall surface 7a1, the channel wall surface 7b1, and the channel wall surface 7c1 are part of the surface of the seal plate 4, and the channel wall surface 7a2, the channel wall surface 7b2, and the channel wall surface 7c2 are housings. The structure which consists of a part of 5 surface was demonstrated. However, the present invention is not limited to this. For example, when the first guide vane 7d and the second guide vane 7e are fixed to the vane plate, and the vane plate is fixed to the seal plate 4 and the housing 5, the channel wall surface 7a1, the channel wall surface 7b1, the channel wall surface 7c1, the flow path wall surface 7a2, the flow path wall surface 7b2, and the flow path wall surface 7c2 may be formed of a part of the surface of the vane plate. In some cases, a shroud for adjusting a gap with the radial impeller 2 may be provided on the housing 5 side. In such a case, it is also possible to adopt a configuration in which the channel wall surface 7a2, the channel wall surface 7b2, and the channel wall surface 7c2 are part of the surface of the shroud.

  DESCRIPTION OF SYMBOLS 1 ... Centrifugal compressor, 2 ... Radial impeller, 2a ... Base, 2b ... Blade, 3 ... Shaft, 4 ... Seal plate, 5 ... Housing, 5a ... Suction port, 5b ... Discharge port 5c: scroll channel, 6: bolt, 7: diffuser, 7a: first annular channel, 7a1: channel wall surface, 7a2: channel wall surface, 7b: second annular channel, 7b1: Channel wall surface, 7b2: Channel wall surface (inclined surface), 7c: Intermediate channel, 7c1: Channel wall surface, 7c2: Channel wall surface, 7d: First guide vane, 7e ... Second guide vane, X ... Air (fluid)

Claims (3)

A centrifugal compressor comprising a radial impeller that applies velocity energy to a fluid and sends the fluid in a radial direction, and a diffuser that decelerates and pressurizes the fluid sent from the radial impeller,
The diffuser is
A first annular flow path that is provided between the radial impellers and formed between a pair of planar flow path wall surfaces facing each other in parallel;
A second ring formed between a pair of planar channel wall surfaces that are provided outside the first annular channel and face each other in parallel with a wider interval than the channel wall surface forming the first annular channel. A flow path;
A first guide vane installed in the first annular channel;
A centrifugal compressor comprising: a second guide vane installed in the second annular flow path and having a blade height larger than that of the first guide vane.   The diffuser is provided between the first annular channel and the second annular channel, and includes a channel wall surface forming the first annular channel and a channel wall surface forming the second annular channel. The centrifugal compressor according to claim 1, further comprising an intermediate flow path having an inclined surface connecting the two.   3. The centrifugal compressor according to claim 1, wherein the second guide blade is installed on an extension line of the fluid guide direction of the first guide blade. 4.

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