KR101429516B1

KR101429516B1 - Centrifugal Compressor

Info

Publication number: KR101429516B1
Application number: KR1020100028604A
Authority: KR
Inventors: 김승민
Original assignee: 삼성테크윈 주식회사
Priority date: 2010-03-30
Filing date: 2010-03-30
Publication date: 2014-08-14
Also published as: KR20110109056A

Abstract

A centrifugal compressor according to the present invention includes a casing, an impeller rotatably disposed in the casing, and a rotor disposed around the periphery of the impeller and rotatably disposed And a plurality of second diffuser vanes disposed along the circumference of the impeller between the impeller and the first diffuser vane and fixedly disposed inside the casing.

Description

[0001] Centrifugal Compressor [0002]

The present invention relates to a centrifugal compressor, and more particularly to a centrifugal compressor having a variable diffuser vane.

The centrifugal compressor is a device that allows a fluid to pass through a rotating impeller at high speed, thereby compressing the fluid by centrifugal force.

Such centrifugal compressors typically have a plurality of diffuser vanes on a circumference about an impeller. The fluid radially moved by the impeller is decelerated by the diffuser vane and is compressed as the pressure increases.

On the other hand, the performance characteristics of the centrifugal compressor, that is, compression ratio and efficiency, are changed depending on the shape and arrangement of the diffuser vanes. Therefore, there is known a centrifugal compressor having a variable diffuser vane so that a centrifugal compressor can be used in accordance with various use conditions.

Since the variable diffuser vane is rotatably disposed inside the casing of the centrifugal compressor, by properly rotating the variable diffuser vane as the temperature of the inflow fluid changes, the compression characteristics of the centrifugal compressor can be effectively changed according to the situation. That is, the centrifugal compressor equipped with the variable diffuser vane has an advantage that the operating range is wide.

However, since the variable diffuser vane is rotatably disposed inside the casing, it is inevitably spaced apart from the casing at a predetermined interval. The clearance between the variable diffuser vane and the casing is generated by errors in fabrication and assembly, so that it is practically impossible to completely eliminate the gap. In this case, there is a problem that the compression characteristics of the centrifugal compressor are changed or the performance of the centrifugal compressor is deteriorated.

Particularly, when the gap between the variable diffuser vane and the inner surface of the casing is large or the velocity of the fluid passing between the variable diffuser vanes is high, more fluid escapes through the gap, The deterioration of the performance becomes more significant.

In order to solve the above problems, the present invention provides a centrifugal compressor having a variable diffuser vane and capable of effectively suppressing a reduction in compression ratio and efficiency due to a gap between the variable diffuser vane and the casing, .

In order to achieve the above object, a centrifugal compressor according to the present invention includes a casing, an impeller rotatably disposed in the casing, and a rotor disposed in the casing along the circumference of the impeller, A plurality of first diffuser vanes and a plurality of second diffuser vanes disposed along the circumference of the impeller between the impeller and the first diffuser vane and fixedly disposed inside the casing.

According to the centrifugal compressor according to the present invention, since the variable diffuser vane is provided, the compression ratio and efficiency are effectively prevented from being reduced due to the gap between the variable diffuser vane and the casing while the operation range is wide.

1 is a schematic cross-sectional view of a centrifugal compressor according to an embodiment of the present invention.
Fig. 2 is a schematic enlarged view of part II of Fig.
3 is a schematic enlarged view of part III of Fig.
4 is a schematic plan view of a part of a conventional centrifugal compressor.
5 is a schematic plan view of a part of the configuration of the centrifugal compressor shown in Fig.
FIG. 6 is a graph schematically showing a relationship between a flow rate and a compression ratio according to a change in the clearance between the variable diffuser vane and the casing in a conventional centrifugal compressor.
7 is a graph schematically showing a relationship between a flow rate and efficiency according to a change in the clearance between the variable diffuser vane and the casing in the conventional centrifugal compressor.
FIG. 8 is a graph schematically illustrating a relationship between a flow rate and a compression ratio of a centrifugal compressor according to an exemplary embodiment of the present invention, wherein a relationship between a variable diffuser vane and a casing varies according to a change in a gap.
FIG. 9 is a graph schematically illustrating a relationship between flow rate and efficiency according to a change in gap between a variable diffuser vane and a casing in a centrifugal compressor according to an embodiment of the present invention.
10 is a schematic cross-sectional view of a centrifugal compressor according to another embodiment of the present invention.

Hereinafter, a centrifugal compressor according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a centrifugal compressor according to an embodiment of the present invention, FIG. 2 is a schematic enlarged view of a portion II of FIG. 1, and FIG. 3 is a schematic enlarged view of a portion III of FIG. FIG. 4 is a schematic plan view of a part of a conventional centrifugal compressor, and FIG. 5 is a schematic plan view of a part of the configuration of the centrifugal compressor shown in FIG. FIG. 6 is a graph schematically showing a relationship between a flow rate and a compression ratio according to a change in the clearance between the variable diffuser vane and the casing in a conventional centrifugal compressor. 7 is a graph schematically showing a relationship between a flow rate and efficiency according to a change in the clearance between the variable diffuser vane and the casing in the conventional centrifugal compressor. FIG. 8 is a graph schematically illustrating a relationship between a flow rate and a compression ratio of a centrifugal compressor according to an exemplary embodiment of the present invention, wherein a relationship between a variable diffuser vane and a casing varies according to a change in a gap. FIG. 9 is a graph schematically illustrating a relationship between flow rate and efficiency according to a change in gap between a variable diffuser vane and a casing in a centrifugal compressor according to an embodiment of the present invention.

1 to 3 and 5, the centrifugal compressor 1 according to the present embodiment includes a casing 100, an impeller 200, a first diffuser vane 300, and a second diffuser vane 400 do.

The casing 100 has an internal space 150 therein and includes an inlet 112 through which the fluid flows and an outlet through which the introduced fluid flows (not shown). In this embodiment, the casing 100 includes a shroud 110 and a volute 120. The inlet 112 is provided in the shroud 110 and the bolt 120 is disposed around the shroud 110. The fluid introduced into the inlet 112 passes through the interior of the shroud 110 to the volute 120 and exits the centrifugal compressor 1 through an outlet (not shown) formed in the bolt 120.

The impeller 200 is rotatably disposed in the inner space 150 of the casing, that is, the inner space of the shroud 110. The rotating shaft 220 of the impeller 200 is coupled to the casing 100 by a mechanical seal (not shown) or the like so as to be rotatable with respect to the casing 100 so as to prevent the fluid from leaking to the coupling portion. The impeller 200 has an impeller vane 210 disposed radially about its rotation center axis C1. Accordingly, when the impeller 200 rotates, the inflow fluid is forced to move radially by the impeller vane 210.

A plurality of first diffuser vanes 300 are disposed in the inner space 150 of the casing 100, that is, inside the shroud 110. Referring to FIG. 4, the first diffuser vane 300 is arranged around the impeller 200 so as to extend in a circumferential direction, and extends in a direction away from the impeller 200. The first diffuser vane 300 is a variable diffuser vane and rotatably disposed at a predetermined angle with respect to the casing 100 about the rotation axis 310 thereof.

2, the rotation axis 310 of the first diffuser vane 300 is rotatably coupled to the casing 100 and the rotation center axis C2 of the first diffuser vane 300 is connected to the rotation center axis C1 of the impeller 200 Are arranged in parallel. One side of the rotating shaft 310 of the first diffuser vane 300 is connected to driving means (not shown) disposed outside the casing 100 so that the first diffuser vane 300 is rotated. Meanwhile, a clearance may be formed between the first diffuser vane 300 and the inner circumferential surface 102 of the casing 100 due to manufacturing or assembly errors. That is, the first diffuser vane 300 and the casing 100 may be spaced apart by a predetermined spacing d.

Meanwhile, the rotation angle of the first diffuser vane 300 is appropriately adjusted in consideration of the temperature, compression ratio, and efficiency of the fluid flowing into the centrifugal compressor.

The second diffuser vane 400 is disposed in the interior space 150 of the casing 100 between the impeller 200 and the first diffuser vane 300, that is, inside the shroud 110. The second diffuser vane 400 is disposed to draw a circumference along the inner circumference of the first diffuser vane 100 and the outer circumference of the impeller 200. That is, the first diffuser vane 300 and the second diffuser vane 400 are disposed concentrically around the impeller 200.

Each second diffuser vane 400 is disposed so as to extend in a direction away from the impeller 200 and is fixedly attached to the inner surface of the housing 100. The second diffuser vane 400 may be integrally formed with the casing 100 or the shroud 110 and may be tightly fixed to the casing 100 or welded to the inner surface 102 of the casing 100, And may be tightly fixed to the side surface. Since the second diffuser vane 400 is in close contact with the inner side surface 102 of the casing 100, no gap is formed between the second diffuser vane 400 and the inner side surface 102 of the casing 100. Therefore, the fluid can not escape between the second diffuser vane 400 and the inner surface 102 of the casing 100.

Generally, the higher the solididy of the diffuser vane in the centrifugal compressor, the higher the efficiency. The higher the solubility of the diffuser vanes disposed outside, the higher the efficiency. Therefore, in the centrifugal compressor 1 according to the present embodiment, the efficiency of the first diffuser vane 300 can be effectively increased by making the extension length of the first diffuser vane 300 longer than the extension length of the second diffuser vane 400.

Next, operation modes and effects of the centrifugal compressor 1 according to the present embodiment will be described.

Referring to FIG. 5, when the impeller 200 rotates, the fluid that has flowed into the inlet 112 is forced to move radially as indicated by a solid arrow. The fluid pressurized radially from the impeller 200 passes through the second diffuser vane 400 and the first diffuser vane 100 in turn and flows into the volute 120. In this process, fluid is passed between the second diffuser vanes 400 and between the first diffuser vanes 300 to decrease the velocity and increase the pressure.

4, the conventional centrifugal compressor includes a first diffuser vane 300, which is a variable vane, but does not include a second diffuser vane that is fixedly disposed inside the first diffuser vane 300. As shown in FIG. As the fluid passes between the first diffuser vanes 300, some fluid escapes into the gap between the first diffuser vane 300 and the casing 100. Since the conventional centrifugal compressor has no second diffuser vane, the velocity of the fluid passing between the first diffuser vanes 300 is fast. Therefore, even if the gap between the first diffuser vane 300 and the casing 100 is small, a large amount of fluid escapes into the gap. That is, a large amount of fluid is moved from the high pressure side to the low pressure side of the first diffuser vane 300 through the gap, as indicated by the dotted arrow in Fig.

Since the conventional centrifugal compressor has a large amount of fluid passing through the gap between the first diffuser vane 300 and the inner surface 112 of the casing 100, the compression characteristics and efficiency of the centrifugal compressor 1 are affected. As the distance between the first diffuser vane 300 and the casing 100 increases, the greater the speed of the fluid passing through the first diffuser vane 300, the greater the amount of fluid moving to the gap. 1 < / RTI >

However, since the centrifugal compressor 1 according to the present embodiment includes the second diffuser vane 400 between the first diffuser vane 300 and the impeller 200, unlike the conventional centrifugal compressor, the fluid flows from the first diffuser vane 300 The speed is first reduced prior to entering the space between the first and second plates 300 and 300. Thus effectively reducing the amount of fluid moving into the gap between the first diffuser vane 300 and the inner side 102 of the casing 100. As a result, the centrifugal compressor 1 according to the present embodiment is advantageous in that the compression characteristics and efficiency are not significantly changed even if a slight gap is formed between the first diffuser vane 300 and the housing 100.

The results of the numerical analysis for supporting this are shown in Figs. 6 to 9.

The graphs shown in FIGS. 6 and 7 are the results of the numerical analysis of the conventional centrifugal compressor lacking the second diffuser vane 400 in the centrifugal compressor 1 according to the present embodiment, and the second diffuser vane 300 Flow rate and isentropic efficiency with different spacing d between the inner circumferential surface 102 of the casing 100 and the inner circumferential surface 102 of the casing 100. [ Referring to FIGS. 6 and 7, it can be seen that as the separation distance d changes, the compression ratio and the isentropic efficiency vary with the same flow rate. The performance characteristics of the centrifugal compressor are not significantly different from those in the case where the spacing distance d between the first diffuser vane 300 and the casing 100 is 0.05 mm or less. However, when the spacing distance d is 0.05 mm, the performance characteristics of the centrifugal compressor are remarkably changed. Therefore, in order to maintain the performance characteristics of the centrifugal compressor 1, the spacing d between the first diffuser vane 300 and the casing 100 should be maintained within 0.05 mm. However, it is very difficult to fabricate the centrifugal compressor so that the spacing d between the first diffuser vane 300 and the casing 100 is within 0.05 mm.

8 and 9 are a result of a numerical analysis of the centrifugal compressor 1 according to the present embodiment having the second diffuser vane 400 together with the first diffuser vane 300, 300 and the spacing distance d between the inner circumferential surface 102 of the casing 100 and the flow rate, compression ratio, flow rate, and isentropic efficiency. 8 and 9, in the centrifugal compressor 1 according to the present embodiment, even when the spacing d between the first diffuser vane 300 and the casing 100 is 0.05 mm to 0.4 mm, It can be seen that the compression ratio and isentropic efficiency are not significantly different from those in the case where the separation distance d does not exist.

That is, the performance characteristics of the centrifugal compressor 1 according to the present embodiment are maintained substantially constant within the gap distance d between the first diffuser vane 300 and the casing 100 within 0.4 mm. Therefore, even if a gap is slightly generated between the first diffuser vane 300 and the housing 100 due to manufacturing errors or the like, the centrifugal compressor 1 according to the present embodiment can effectively suppress the change in the performance characteristics thereof.

Next, a centrifugal compressor according to another embodiment of the present invention will be described with reference to the drawings.

10 is a schematic view of a centrifugal compressor 2 according to another embodiment of the present invention in the same manner as the centrifugal compressor 1 according to the embodiment described above except that the casing 100, the impeller 200, the first diffuser vane 300, A diffuser vane 400, and a third diffuser vane 800 are additionally provided. In this embodiment, the components having the same member numbers as those of the centrifugal compressor 2 according to the above-described embodiment are substantially the same in construction, and a detailed description thereof will be omitted.

10, the third diffuser vane 800 is disposed along the outer circumference of the first diffuser vane 300 and is rotatable in the inner space 150 of the casing 100, like the first diffuser vane 300 Which is a variable diffuser vane. The third diffuser vane 800 is disposed between the first diffuser vane 300 and the bolt 120 and may have the same configuration as the first diffuser vane 300. Accordingly, in the centrifugal compressor 2 according to the present embodiment, the first diffuser vane 300 and the second diffuser vane 800 operate together, and the variation of the performance characteristics of the first diffuser vane 300 and the second diffuser vane 800 can be further increased.

The first diffuser vane 300 and the third diffuser vane 800 are disposed on the inner circumference of the first diffuser vane 300 in the centrifugal compressor 1 according to the present embodiment, Reduces the speed of fluid passing through. Thus effectively reducing the amount of fluid escaping into the gap between the first diffuser vane 300 and the third diffuser vane 800 and the inner side 102 of the casing 100. Therefore, the centrifugal compressor 2 according to the present embodiment is not significantly affected by the performance characteristics even if a slight gap is generated due to errors in assembly or fabrication.

Although the first diffuser vane 300 is formed to be longer than the second diffuser vane 400 in the centrifugal compressors 1 and 2 according to the above embodiments, May be the same or smaller than the second diffuser vane 400.

Although the centrifugal compressor according to some embodiments of the present invention has been described above, the present invention is not limited thereto, and may be embodied in various forms within the technical scope of the present invention.

1,2 ... Centrifugal compressor 100 ... casing
110 ... Shroud 112 ... Inlet
120 ... Volute 200 ... Impeller
210 ... impeller vane 220 ... rotating shaft
300 ... first diffuser vane 400 ... second diffuser vane
800 ... 3rd diffuser vane C1 ... impeller rotation center axis
C2 ... First diffuser vane rotation center axis
C3 ... third diffuser vane rotation center axis

Claims

A casing,
An impeller rotatably disposed in the casing,
A plurality of first diffuser vanes rotatably disposed in the casing, the plurality of first diffuser vanes passing through the impeller,
And a plurality of second diffuser vanes disposed between the impeller and the first diffuser vane and fixedly disposed within the casing.

delete

Claim 3 has been abandoned due to the setting registration fee.

The method according to claim 1,
The first diffuser vane,
And spaced apart from the inner surface of the casing by an interval of 0.05 mm to 4 mm.

Claim 4 has been abandoned due to the setting registration fee.

The method according to claim 1,
Wherein the second diffuser vane comprises:
Wherein the extension length is longer than the extension length of the first diffuser vane.

The method according to claim 1,
And a plurality of third diffuser vanes disposed further away from the first diffuser vane in a radial direction with respect to a rotation center axis of the impeller and rotatably disposed in the casing.