CN117432637A

CN117432637A - Centrifugal compressor

Info

Publication number: CN117432637A
Application number: CN202210974794.6A
Authority: CN
Inventors: 林文凯; 李训安
Original assignee: Fusheng Co Ltd
Current assignee: Fusheng Co Ltd
Priority date: 2022-07-15
Filing date: 2022-08-15
Publication date: 2024-01-23
Also published as: TW202405312A; TWI827145B; CN218266395U

Abstract

The invention provides a centrifugal compressor which comprises an air inlet, a runner, a first-stage impeller, a second-stage impeller, a backflow guide vane base and an economizer injection channel. The runner is provided with a first diffusion section, a first turning section, a backflow section, a second turning section, a second diffusion section and a volute runner. The volute runner is connected with the second diffusion section. The first stage impeller is arranged between the air inlet and the first diffusion section. The second-stage impeller is arranged between the second turning section and the second diffusion section. The backflow guide vane base is provided with a plurality of backflow wings positioned in the backflow section and a plurality of injection holes communicated with the backflow section. Each reflow wing has a first wing portion, a second wing portion, and a slit between the first wing portion and the second wing portion. The plurality of injection holes respectively fall into the plurality of slits. The economizer injection passage communicates with the plurality of injection holes.

Description

Centrifugal compressor

Technical Field

The present invention relates to a centrifugal compressor, and more particularly, to a two-stage centrifugal compressor.

Background

A typical two-stage centrifugal compressor includes a first stage impeller located upstream of a flow passage and a second stage impeller located downstream of the flow passage. First, a first fluid (e.g., gaseous refrigerant, air, carbon dioxide, etc.) flows from the inlet guide vanes to the first stage impeller along the long axis of the drive shaft, and then the first stage impeller pressurizes the first fluid and forces the first fluid into the flow channel along the centrifugal direction. The first fluid then turns at the first turn section of the flow path and flows in a centripetal direction toward the second stage impeller. In detail, the second stage impeller is disposed corresponding to the second turning section of the flow channel, and the economizer injection channel is communicated with the second turning section of the flow channel, so as to inject the second fluid (such as gaseous refrigerant, air or carbon dioxide) into the second turning section of the flow channel, so that the first fluid and the second fluid form a third fluid in the second turning section of the flow channel. The third fluid then flows to the second stage impeller and is pressurized by the second stage impeller to flow in the centrifugal direction to the volute flow path

In general, a backflow vane mount may be disposed between the first stage impeller and the second stage impeller, and the second fluid from the economizer is directed through a plurality of backflow wings on the backflow vane mount to be injected into the second turning section of the flow channel. Furthermore, a backflow channel is formed between any two adjacent backflow wings, turbulence is easily generated in the backflow channel by the second fluid, the first fluid and the second fluid cannot be uniformly mixed, and problems of increased pressure loss, lower aerodynamic efficiency and the like of the fluid are derived, so that performance of the centrifugal compressor is affected.

Disclosure of Invention

The invention aims at a centrifugal compressor, which is beneficial to reducing turbulent flow generation between bases of backflow guide vanes and improving compression efficiency.

According to an embodiment of the invention, a centrifugal compressor includes an air intake, a flow passage, a first stage impeller, a second stage impeller, a backflow vane mount, and an economizer injection passage. The runner is communicated with the air inlet and is provided with a first diffusion section, a first turning section connected with the first diffusion section, a backflow section connected with the first turning section, a second turning section connected with the backflow section, a second diffusion section connected with the second turning section and a volute runner connected with the second diffusion section. The first stage impeller is arranged between the air inlet and the first diffusion section. The second-stage impeller is arranged between the second turning section and the second diffusion section. The backflow guide vane base is arranged between the first-stage impeller and the second-stage impeller and is provided with a plurality of backflow wings positioned in the backflow section and a plurality of injection holes communicated with the backflow section. Each of the return wings has a first wing portion, a second wing portion, and a slit separating the first wing portion from the second wing portion. The plurality of injection holes respectively fall into the plurality of slits. The economizer injection passage communicates with the plurality of injection holes.

In an embodiment of the present invention, the slit of the backflow wing has two opposite outlets, and a distance between the two outlets is D. The distance between the injection hole and one of the outlets is between 1/4D and D.

In an embodiment of the present invention, the first wing portion of the above-mentioned reflow wing has an outer end portion with respect to the slit, and the second wing portion of each reflow wing has an inner end portion with respect to the slit. The distance between the outer end of the first wing part and the inner end of the second wing part is S, and the distance between the slit and the inner end of the second wing part is between 3/4S and 1/2S.

In an embodiment of the present invention, the airfoil of the above-mentioned reflow wing includes a concave-convex airfoil, a plano-convex airfoil, a symmetrical airfoil, an S-shaped airfoil, and a flat airfoil.

In an embodiment of the invention, the centrifugal compressor further includes a driving shaft, and the first-stage impeller and the second-stage impeller are sleeved on the driving shaft.

In an embodiment of the present invention, the center axis of the injection hole is parallel to the driving shaft.

In an embodiment of the present invention, the central axis of the injection hole is perpendicular to the backflow section.

In an embodiment of the present invention, the injection hole includes a taper hole, a straight hole, or a combination of a taper hole and a straight hole.

In an embodiment of the present invention, the slit of the reflow wing includes an arc slit or a linear slit.

In an embodiment of the invention, the backflow guide vane base has a first surface located in the backflow section and a second surface opposite to the first surface, and the plurality of injection holes penetrate through the first surface and the second surface.

In an embodiment of the invention, the first wing portion and the second wing portion of the reflow wing protrude from the first surface.

In an embodiment of the invention, the injection hole has a first opening communicating with the slit and a second opening opposite to the first opening, and an aperture of the first opening is smaller than an aperture of the second opening.

In an embodiment of the present invention, the injection hole is located at a position adjacent to the first turning section of the backflow section.

In an embodiment of the present invention, the injection hole is located at a position of the return section away from the second turning section.

In an embodiment of the invention, the centrifugal compressor further comprises an economizer, which is communicated with the economizer injection passage and is arranged outside the centrifugal compressor.

In an embodiment of the invention, the centrifugal compressor further comprises an air inlet guide vane arranged at the air inlet.

In an embodiment of the invention, the backflow guide vane base has a third surface located in the first diffuser and a fourth surface opposite to the third surface, and the plurality of injection holes penetrate through the third surface and the fourth surface.

In an embodiment of the present invention, the first wing portion and the second wing portion of each of the above-mentioned reflow wings protrude from the third surface.

Based on the above, in the centrifugal compressor of the present invention, the injection position of the second fluid falls within the backflow section of the flow passage, so that the first fluid and the second fluid have a longer flow path to be uniformly mixed before flowing to the second-stage impeller. On the other hand, the second fluid injected into the backflow section of the runner generates diversion and carries out first rectification in the slit, and then the second fluid flows from the backflow section to the second turning section along the outer periphery of the second wing part of the backflow wing, and carries out second rectification, so that the flow direction of the second fluid in the backflow section is consistent with that of the first fluid, the generation of turbulent flow is reduced, the first fluid and the second fluid can be uniformly mixed in the runner, the pressure loss of the fluid is reduced, the aerodynamic efficiency is improved, and the compression efficiency of the centrifugal compressor is improved.

Drawings

FIG. 1A is a schematic cross-sectional view of a centrifugal compressor according to an embodiment of the present invention;

FIG. 1B is an enlarged schematic view of region R of FIG. 1A;

FIGS. 2A-2C are schematic views of a backflow vane mount of an embodiment of the present disclosure at different viewing angles;

FIGS. 3-7 are schematic top views of backflow vane mounts of other embodiments of the present disclosure;

FIG. 8 is an enlarged partial schematic view of a centrifugal compressor according to another embodiment of the invention;

fig. 9 is an enlarged partial schematic view of a centrifugal compressor according to still another embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the description to refer to the same or like parts.

Fig. 1A is a schematic cross-sectional view of a centrifugal compressor according to an embodiment of the present invention. Fig. 1B is an enlarged schematic view of region R of fig. 1A. Referring to fig. 1A and 1B, in the present embodiment, the centrifugal compressor 100 may be a two-stage centrifugal compressor, and includes an air inlet 110, a flow passage 120, an air inlet guide vane 140, a driving shaft 150, a first stage impeller 160, a second stage impeller 170, a return guide vane base 180, and an economizer injection passage 190. The air intake 110 is in communication with the flow passage 120, wherein the air intake guide vanes 140 are disposed at the air intake 110, and the first stage impeller 160, the second stage impeller 170, the return guide vane mount 180, and the economizer injection passage 190 are disposed along the flow passage 120. In addition, the first stage impeller 160 and the second stage impeller 170 are sleeved on the driving shaft 150 to synchronously and co-rotate with the driving shaft 150.

In detail, the flow passage 120 has a first diffuser 121, a first turning section 122, a return section 123, a second turning section 124, a second diffuser 125 and a volute flow passage 130, and the first diffuser 121, the first turning section 122, the return section 123, the second turning section 124 and the second diffuser 125 are sequentially arranged between the air inlet 110 and the volute flow passage 130.

The air inlet 110 is connected to the first diffuser 121, and the first stage impeller 160 is disposed between the air inlet 110 and the first diffuser 121. The first turn section 122 is connected to the first diffuser section 121, and the return section 123 is connected to the first turn section 122. The second turning section 124 is connected to the return section 123, and the second diffuser section 125 is connected to the second turning section 124. The second-stage impeller 170 is disposed between the second turning section 124 and the second diffuser 125, and the volute runner 130 is connected to the second diffuser 125.

During operation of the centrifugal compressor 100, a first fluid F1 (e.g., gaseous refrigerant) is channeled by the inlet guide vanes 140 to the inlet 110 and flows axially (e.g., parallel to the long axis of the drive shaft 150) toward the first stage impeller 160. Next, the first stage impeller 160 pressurizes the first fluid F1 and forces the first fluid F1 into the first diffuser section 121 in a centrifugal direction (e.g., away from the long axis of the drive shaft 150). Next, the first fluid F1 flows from the first diffuser section 121 into the first turn section 122 and turns to flow into the return section 123 in a centripetal direction (e.g., a direction near the long axis of the drive shaft 150). On the other hand, the centrifugal compressor 100 further includes an economizer (not shown) that communicates with the economizer injection passage 190 and is disposed outside the centrifugal compressor 100. Wherein the economizer injection passage 190 is in communication with the return section 123 to inject a second fluid F2 (e.g., a gaseous refrigerant) into the return section 123 such that the first fluid F1 and the second fluid F2 form a third fluid F3 within the return section 123. Then, the third fluid F3 flows from the return section 123 into the second turning section 124. Thereafter, the second stage impeller 170 pressurizes the third fluid F3 and drives the third fluid F3 to flow into the second diffuser section 125 in a centrifugal direction and from the second diffuser section 125 into the volute flow path 130.

Continuing to the above, the injection position of the second fluid F2 falls within the backflow section 123 of the flow passage 120, so that the first fluid F1 and the second fluid F2 have a longer flow path to be uniformly mixed before flowing to the second stage impeller 170, thereby improving the compression efficiency of the centrifugal compressor 100. The first fluid F1 and the second fluid F2 may be a gaseous refrigerant, air, carbon monoxide, carbon dioxide, oxygen, hydrogen, or a mixture thereof.

Fig. 2A-2C are schematic views of a backflow vane mount according to an embodiment of the present disclosure at different viewing angles. Referring to fig. 1B, 2A and 2B, in the present embodiment, a backflow vane mount 180 is disposed between the first stage impeller 160 and the second stage impeller 170, and has a plurality of backflow wings 181 located in the backflow section 123 and a plurality of injection holes 182 communicating with the backflow section 123. The plurality of backflow wings 181 are arranged radially, and each backflow wing 181 is provided with an injection hole 182. In detail, each of the return wings 181 has a first wing 183, a second wing 184, and a slit 185 between the first wing 183 and the second wing 184, and the first wing 183 and the second wing 184 are separated by the slit 185. In addition, the injection hole 182 falls within the slit 185, wherein the economizer injection passage 190 communicates with the injection hole 182, and the injection hole 182 communicates with the return section 123 through the slit 185, so that the second fluid F2 can be injected into the return section 123 through the injection hole 182 and the slit 185.

As shown in fig. 1A and 1B, the central axis of the injection hole 182 is parallel to the driving shaft 150 and substantially perpendicular to the return section 123, so that the second fluid F2 can be directly injected into the return section 123 in the axial direction. In other embodiments, the central axis of the injection hole 182 is inclined to the return section 123, so that the second fluid F2 may be sprayed obliquely into the return section 123.

Referring to fig. 1B, 2A, 2B and 2C, in the present embodiment, the wing profile of each of the reflow wings 181 is a concave-convex wing profile, and the slit 185 of each of the reflow wings 181 is an arc-shaped slit. On the other hand, the backflow vane mount 180 has a first surface 186 located within the backflow section 123 and a second surface 187 opposite the first surface 186, and the plurality of injection holes 182 penetrate through the first surface 186 and the second surface 187. Specifically, the first wing 183 and the second wing 184 of each of the backflow wings 181 protrude from the first surface 186, when the second fluid F2 flows into the slit 185 from the injection hole 182, the second fluid F2 can be split and first rectified in the slit 185 to flow along two opposite wings of the second wing 184, so as to achieve the second rectification effect through near-wall effect (near-wall effect), and flow from the backflow section 123 to the second turning section 124.

As shown in fig. 1B, 2B, and 2C, each injection hole 182 has a first opening 188 communicating with the slit 185 and a second opening 189 opposite the first opening 188, wherein the first opening 188 connects the first surface 186 and the second opening 189 connects the second surface 187. In detail, the second fluid F2 from the economizer injection passage 190 flows from the second opening 189 to the first opening 188, and then flows from the first opening 188 into the slit 185. Since the aperture A1 of the first opening 188 is smaller than the aperture A2 of the second opening 189, it helps to increase the pressure loss of the second fluid F2 as the second fluid F2 is injected into the slit 185 or the return segment 123.

As shown in FIG. 1B, in the present embodiment, the injection hole 182 may be a tapered hole, and the aperture decreases from the second surface 187 to the first surface 186. In another embodiment, the injection holes 182 may be straight holes with a uniform aperture from the second surface 187 to the first surface 186. In yet another embodiment, the injection hole 182 may be a combination of a tapered hole and a straight hole, wherein the tapered hole connects the second surface 187 and the straight hole connects the first surface 186.

As shown in fig. 2C, in the present embodiment, the slit 185 of each of the return wings 181 has two opposite outlets 185a, wherein a distance between the two outlets 185a is D (i.e., a length of the slit 185), and a distance D1 between the injection hole 182 (e.g., the first opening 188 of the injection hole 182) and one of the outlets 185a is between 1/4D and D. For example, the position of the injection hole 182 may be at the center of gravity of the return wing 181.

As shown in fig. 1B and 2C, the first wing 183 of each return wing 181 is farther from the second turning section 124 than the second wing 184, wherein the first wing 183 has an outer end 183a opposite the slit 185 and the second wing 184 has an inner end 184a opposite the slit 185. The slit 185 of each return wing 181 is located between the outer end 183a of the first wing 183 and the inner end 184a of the second wing 184, with the inner end 184a being closer to the second turning section 124 than the slit 185. The distance between the outer end portion 183a of the first wing portion 183 and the inner end portion 184a of the second wing portion 184 of each of the return wings 181 is S (i.e., the length of the return wing 181), and the distance S1 between the slit 185 and the inner end portion 184a of the second wing portion 184 is between 3/4S and 1/2S, i.e., the slit 185 is disposed at the center of gravity of the return wing 181. In addition, the first fluid F1 rectifies between the two adjacent reflow wings 181 along the reflow section 123, and the second fluid F2 injected into the reflow section 123 is split and rectified for the first time in the slit 185, and then the second fluid F2 rectifies for the second time along the outer periphery of the second wing 184 of the reflow wing 181 and merges with the first fluid F1. Wherein the injection holes 182 falling into the return wings 181 are located at the position of the return section 123 adjacent to the first turning section 122 and away from (or far from) the second turning section 124, so that the first fluid F1 and the second fluid F2 have a longer flow path to be uniformly mixed before flowing to the second-stage impeller 170, thereby improving the compression efficiency of the centrifugal compressor 100.

As shown in fig. 1B and 2A, the second fluid F2 is injected into the flow channel 120 along the axial direction (e.g., parallel to the long axis direction of the driving shaft 150), and the injection position of the second fluid F2 falls within the backflow section 123 of the flow channel 120. After the second fluid F2 is injected into the backflow section 123, the second fluid F2 is split and subjected to the first rectification in the slit 185, and then the second fluid F2 flows from the backflow section 123 to the second turning section 124 along the outer periphery of the second wing 184 of the backflow wing 181, so as to perform the second rectification and merge with the first fluid F1, so that the second fluid F2 in the backflow section 123 is consistent with the flow direction of the first fluid F1, and the turbulence is reduced, so that the first fluid F1 and the second fluid F2 can be uniformly mixed in the flow channel 120 to form the third fluid F3, thereby reducing the fluid pressure loss and improving the aerodynamic efficiency, and further improving the compression efficiency of the centrifugal compressor 100.

Referring to fig. 1B, the second surface 187 of the return vane mount 180 abuts the sealed space 101, wherein the economizer injection passage 190 communicates with the injection hole 182 through the sealed space 101, and a seal 102 is provided between the return vane mount 180, the second stage impeller 170 and the casing to prevent the second fluid F2 from escaping.

Fig. 3-7 are schematic top views of backflow vane mounts of other embodiments of the present disclosure. As shown in fig. 3, the slit 185 of the return wing 181 shown in fig. 2C is an arc-shaped slit, except that the slit 1851 of the return wing 181a of the present embodiment is a linear slit, and the linear slit extends in a tangential direction of the center circle. As shown in fig. 4, the airfoil of the return wing 181 shown in fig. 2C is a concave-convex airfoil, except that the airfoil of the return wing 181b of the present embodiment is a plano-convex airfoil. As shown in fig. 5, the airfoil of the return wing 181 shown in fig. 2C is a concave-convex airfoil, except that the airfoil of the return wing 181C of the present embodiment is an S-shaped airfoil. As shown in fig. 6, the airfoil of the return wing 181 shown in fig. 2C is a concave-convex airfoil, except that the airfoil of the return wing 181d of the present embodiment is a symmetrical airfoil. As shown in fig. 7, the airfoil of the return airfoil 181 shown in fig. 2C is a concave-convex airfoil, except that the airfoil of the return airfoil 181e of the present embodiment is a flat-plate airfoil.

For example, the slots of the return vane shown in fig. 2C-7 may be arc-shaped slots, linear slots, or a combination of arc-shaped slots and linear slots, and the airfoil profile of the return vane on the return vane base may be one or a combination of at least two of the various airfoil profiles shown in fig. 2C-7, depending on different design requirements. In addition, the injection hole can be designed into a straight hole, a taper hole or a combination of the straight hole and the taper hole according to the actual working condition requirement.

Fig. 8 is an enlarged partial schematic view of a centrifugal compressor according to another embodiment of the present invention. Referring to fig. 1B, the backflow guide vane mount 180 of the present embodiment includes a first backflow guide vane mount 180a and a second backflow guide vane mount 180B, wherein the first backflow guide vane mount 180a is located between the second stage impeller 170 and the second backflow guide vane mount 180B, and the second backflow guide vane mount 180B is located between the first backflow guide vane mount 180a and the first stage impeller 160. The first surface 186 of the first backflow vane mount 180a faces the first surface 1861 of the second backflow vane mount 180b, and the first surface 186 of the first backflow vane mount 180a and the first surface 1861 of the second backflow vane mount 180b are both located within the backflow section 123. The return wings 181 protrude from the first surface 186 of the first return vane mount 180a and contact the first surface 1861 of the second return vane mount 180 b.

Next, referring to fig. 8, unlike the above embodiment, the backflow wing 181 of the present embodiment protrudes from the first surface 1861 of the second backflow vane mount 180b and contacts the first surface 186 of the first backflow vane mount 180 a. On the other hand, the injection holes 182 are located at the first return vane mount 180a and aligned with the slits 185 of the return wings 181 located at the second return vane mount 180 b.

Fig. 9 is an enlarged partial schematic view of a centrifugal compressor according to still another embodiment of the present invention. Referring to fig. 9, similarly, the backflow wing 181 'and the injection hole 182' may be disposed in the first diffuser 121 according to different requirements, such that the backflow wing 181 'protrudes from the third surface 186' of the second backflow guide vane base 180b away from the first surface 1861 and is disposed corresponding to the first diffuser 121 and the first stage impeller 160. Specifically, the second backflow vane mount 180b has a third surface 186 'located within the first diffuser section 121 and a fourth surface 187' opposite the third surface 186', and the plurality of injection holes 182' extend through both the third surface 186 'and the fourth surface 187'. In addition, the first wing 183 'and the second wing 184' of each return wing 181 'protrude from the third surface 186'.

The injection position of the second fluid F2 falls in the first diffuser section 121 of the flow channel 120, after the second fluid F2 is injected into the first diffuser section 121, the second fluid F2 is split and subjected to the first rectification in the slit 185', and then the second fluid F2 flows from the first diffuser section 121 to the first diffuser section 122 along the outer periphery of the second wing 184' of the return wing 181', so as to perform the second rectification and merge with the first fluid F1, so that the flow direction of the second fluid F2 in the first diffuser section 121 is consistent with the flow direction of the first fluid F1, and the turbulence is reduced, so that the first fluid F1 and the second fluid F2 can be uniformly mixed in the flow channel 120 to form the third fluid F3, thereby reducing the fluid pressure loss and improving the aerodynamic efficiency, and improving the compression efficiency of the centrifugal compressor 100.

In summary, in the centrifugal compressor of the present invention, the injection position of the second fluid falls within the front end of the backflow section (or the first diffuser section) of the flow passage, so that the first fluid and the second fluid have a longer flow path to be uniformly mixed before flowing to the second-stage impeller. On the other hand, the second fluid injected into the backflow section (or the first diffusion section) of the runner generates diversion and carries out first rectification in the slit, and then the second fluid flows from the backflow section to the second turning section along the outer periphery of the second wing part of the backflow wing, and carries out second rectification, so that the second fluid in the backflow section (or the first diffusion section) is consistent with the flow direction of the first fluid, the generation of turbulent flow is reduced, the first fluid and the second fluid can be uniformly mixed in the runner, the pressure loss of the fluid is reduced, and the aerodynamic efficiency is improved, thereby improving the compression efficiency of the centrifugal compressor.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A centrifugal compressor, comprising:

an air inlet;

the flow passage is communicated with the air inlet and is provided with a first diffusion section, a first turning section connected with the first diffusion section, a backflow section connected with the first turning section, a second turning section connected with the backflow section, a second diffusion section connected with the second turning section and a volute flow passage connected with the second diffusion section;

a first stage impeller disposed between the air inlet and the first diffuser;

the second-stage impeller is arranged between the second turning section and the second diffusion section;

a backflow vane mount disposed between the first stage impeller and the second stage impeller, wherein the backflow vane mount has a plurality of backflow wings located in the backflow section and a plurality of injection holes communicated with the backflow section, each backflow wing has a first wing portion, a second wing portion, and a slit separating the first wing portion from the second wing portion, and the plurality of injection holes respectively fall into the plurality of slits; and

and the economizer injection channel is communicated with the injection holes.

2. The centrifugal compressor according to claim 1, wherein said slit of each of said return wings has two opposite outlets, and a distance between said two outlets is D, and a distance between said injection hole and one of said outlets is between 1/4D and D.

3. The centrifugal compressor of claim 1, wherein the first wing portion of each of the return wings has an outer end portion with respect to the slit, and the second wing portion of each of the return wings has an inner end portion with respect to the slit, a distance between the outer end portion of the first wing portion and the inner end portion of the second wing portion is S, and a distance between the slit and the inner end portion of the second wing portion is between 3/4S and 1/2S.

4. The centrifugal compressor according to claim 1, wherein the airfoil of each of the return airfoils comprises a concave-convex airfoil, a plano-convex airfoil, a symmetrical airfoil, an S-shaped airfoil, and a flat plate airfoil.

5. The centrifugal compressor according to claim 1, further comprising:

the first-stage impeller and the second-stage impeller are sleeved on the driving shaft.

6. The centrifugal compressor according to claim 5, wherein a central axis of the plurality of injection holes is parallel to the drive shaft.

7. The centrifugal compressor of claim 1, wherein a central axis of the plurality of injection holes is perpendicular to the return section.

8. The centrifugal compressor of claim 1, wherein the plurality of injection holes comprise conical holes, straight holes, or a combination of conical and straight holes.

9. The centrifugal compressor of claim 1, wherein the slit of each of the return wings comprises an arc-shaped slit or a linear slit.

10. The centrifugal compressor of claim 1, wherein the backflow vane mount has a first surface within the backflow section and a second surface opposite the first surface, and the plurality of injection holes pass through the first surface and the second surface.

11. The centrifugal compressor of claim 10, wherein the first and second wing portions of each of the return wings protrude from the first surface.

12. The centrifugal compressor according to claim 1, wherein each of the injection holes has a first opening communicating with the corresponding slit and a second opening opposite to the first opening, and a pore diameter of the first opening is smaller than a pore diameter of the second opening.

13. The centrifugal compressor of claim 1, wherein the injection hole is located adjacent the return section to the first turn section.

14. The centrifugal compressor of claim 13, wherein the injection hole is located at the return section away from the second turn section.

15. The centrifugal compressor according to claim 1, further comprising:

and the energy saver is communicated with the energy saver spraying channel and is arranged outside the centrifugal compressor.

16. The centrifugal compressor according to claim 1, further comprising:

and the air inlet guide vane is arranged at the air inlet.

17. The centrifugal compressor of claim 1, wherein the backflow vane mount has a third surface within the first diffuser section and a fourth surface opposite the third surface, and the plurality of injection holes pass through the third and fourth surfaces.

18. The centrifugal compressor of claim 17, wherein the first and second wing portions of each of the return wings protrude from the third surface.