JP3072867B2 - Multistage centrifugal compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multistage centrifugal compressor,
More particularly, the present invention relates to a multistage centrifugal compressor provided with a diffuser suitable for handling high-speed fluid.

[0002]

2. Description of the Related Art In a conventional multi-stage centrifugal compressor in which a plurality of centrifugal compressor stages are arranged on one rotating shaft, a vaneless diffuser has been used.
As described in Japanese Patent Publication No. 411, there has been proposed a general vane diffuser using a vane diffuser having a wide operating range. The feature of the compressor is that the operating range is almost equal to that of the conventional vaneless compressor, and the efficiency can be increased. In a multi-stage compressor having a diffuser with vanes in all stages, for example, as shown in FIG. 3, one rotating shaft 3 has a plurality of impellers 4 attached thereto.
It rotates while being supported by the bearing 2. Handling gas is suction nozzle 5
The pressure is increased by the impeller 4 and discharged from the discharge nozzle 5. A diffuser 9 composed of two opposing walls is provided outward of the impellers 4 of the respective stages, and a vane 7 is provided on the diffuser 9. As the diffuser vanes 7, those having the optimum specifications for improving the performance for each stage are selected. For example, in a compressor, the volumetric flow rate of each stage changes as the gas is compressed,
Since the specific speed represented by the following equation (1) generally decreases as going to the subsequent stage, the specific speed Ms is

[0003]

(Equation 1)

[0004] Here, N is the number of rotations, Q is the volume flow rate, and H is the head.

[0005] Selection is made based on parameters. For example, Hitachi Review published in 1982
w Vol 31. NO. As shown in FIG. 6, the type of the vane may be different between a stage having a large specific speed and a stage having a small specific speed.

In general, the specific velocity becomes low in the stage near the discharge nozzle, and therefore, a small string ratio vane is used. Small string vanes as described in JP-A-53-119411 may be used. An example is shown in FIG. The number of vanes is usually about 10 to 20.

[0007]

The above prior art is effective in increasing the efficiency of the multistage centrifugal compressor. However, no consideration was given to compressor noise.
That is, due to recent urbanization, there are many cases where a general house is formed near a place where a compressor facility is installed, or a new compressor facility must be constructed near a residential area.
For this reason, conventionally, noise generated by the above-described conventional technology has been allowed. However, in recent years, it has actually been no longer allowed or a measure to reduce the noise value has been required.

An object of the present invention is to provide a multi-stage centrifugal compressor capable of reducing compressor noise without lowering efficiency as much as possible.

[0009]

To achieve the above object, a first aspect of the present invention is to provide a casing having at least one suction nozzle and one discharge nozzle, a rotating shaft rotatably supported by the casing. A plurality of impellers supported by the rotating shaft, a plurality of diffusers installed on an outer periphery of each impeller, and formed by two wall surfaces facing each other at an interval in the axial direction; in the installed in at least two diffuser of diffuser, multistage centrifugal compressor in which at least one is provided with a day fuser vane leading to the discharge nozzle of which, the
Change the number of diffuser vanes closest to the discharge nozzle to another.
This is less than the number of diffuser vanes .

In order to achieve the above object, a second aspect of the present invention provides a casing having at least one suction nozzle and a discharge nozzle, a rotating shaft rotatably supported by the casing, and a rotating shaft supported by the rotating shaft. A plurality of diffusers are provided on the outer periphery of each of the impellers, and are formed by two wall surfaces facing each other at an interval in the axial direction, and at least two diffusers of the plurality of diffusers are provided. In a multi-stage centrifugal compressor equipped with a diffuser vane at least one of which is installed in at least one diffuser, at least one of which is connected to the discharge nozzle,
Adjust the inlet diameter of the closest diffuser vane to the other
Install outside of the fuser vane diameter
To, Ru der that the number of the day fuser vane less than the number of the other day fuser vane.

[0013] To achieve the above object, a third invention provides a multistage centrifugal compressor according to the first or second invention.
And the diffuser base closest to the discharge nozzle
Outlet diameter relative to other diffuser vane outlet diameters.
It was made larger .

[0012]

[0013]

It is conventionally known that noise is increased by providing a diffuser vane in a centrifugal compressor, and there is also a technology that considers the relationship between the number of blades of an impeller and the number of diffuser vanes. .

However, when considering a compressor noise propagation path, the thickness of the wall is smaller than that of the casing and the noise from the easily vibrating pipe is large, and the main component of the noise is the number of blades from the impeller. And the frequency component multiplied by the rotation speed is dominant. Therefore, for this purpose, it is necessary to reduce the sound generated from the impeller outlet closest to the discharge nozzle. On the other hand, removing the diffuser vane and replacing it with a conventional vaneless diffuser reduces efficiency.

[0015] Therefore, when installing the inlet diameter of the closest Day fuser vanes ejection exit nozzle outward from inlet diameter other day fuser vane, a force is unsteady flow impeller outlet impinges on Day fuser vane Hatsugi It is represented as f = αmc ² where f is the force that one vane receives due to the wake flow of the impeller outlet, m is the mass of the flow, c is the collision velocity, and α is the coefficient.

[0016]

Therefore , according to the first aspect , the number of vanes of the diffuser vane closest to the discharge nozzle is made smaller than the number of vanes of the other diffuser vanes, so that the number of sound sources is reduced and the size of the sound source is reduced. can do.

[0018] According to the second invention, the discharge nozzle
Adjust the inlet diameter of the closest diffuser vane to the other
Install outside of the fuser vane diameter
In addition, the number of the diffuser vanes is
Since the number of sound sources is smaller than the number of sound sources, the size of the sound source can be further reduced.

When the number of diffuser vanes closest to the discharge nozzle is reduced as in the first or second aspect of the present invention, the number of diffuser vanes is about 1/4 to 3 / It is preferable that the fluid flow angle of the diffuser vane be greatly reduced to the fourth position. In order to prevent this, according to the third aspect , the outlet diameter of the diffuser vane closest to the discharge nozzle is made relatively larger than the outlet diameter of the other diffuser vanes. Therefore, even if the number of diffuser vanes is greatly reduced. Even if reduced, diffuser efficiency can be minimized.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, in this embodiment,
A plurality of impellers 4A, 4B, and 4C are attached to one rotating shaft 3, and the fluid compressed by the leftmost impeller 4A in the drawing is further compressed by the right impeller 4B, and then the rightmost one. Are further compressed by the impeller 4C and discharged from the discharge nozzle 6. In addition, diffusers vanes 7A, 7B, 8 are installed outside the respective impellers 4A, 4B, 4C.
The diffuser vane 8 closest to the discharge nozzle 6 provided outside the rightmost impeller 4C is in the mounting position as shown in the following Expression 2.

[0022]

(Equation 2)

That is, the inlet diameter of the diffuser vane 8 at the impeller stage communicating with the discharge nozzle 6 is relatively larger than at the other stages.

With the above configuration, the flow velocity and noise of the fluid according to the present embodiment will be described below.

Since the inlet diameter of the diffuser vane 8 closest to the rightmost discharge nozzle 6 is formed larger than the inlet diameters of the other diffuser vanes, the fluid discharged from the impeller 4C collides with the diffuser vane 8. The flow velocity during the run is reduced. Therefore, when the fluid collides with the inlet diameter of the diffuser vane, the sound source becomes small.

On the other hand, the impellers 4A and 4B of the other stages are positioned at the optimum positions with priority given to efficiency improvement.
Since B is installed, the power of sound increases. However, the casing 1 is sufficiently thicker than the pipe, and the impeller 4C is provided between the casing 1 and a discharge pipe (not shown) connected to the discharge nozzle 6, so that the impeller 4A is provided. , The sound due to 4B, ie the pressure fluctuation from upstream,
It is mixed by the impeller 4C and the diffuser vane 8 and hardly propagates to the discharge pipe. Therefore, compressor noise can be reduced without lowering the efficiency of the multi-stage centrifugal compressor.

FIG. 2 shows a second embodiment of the present invention.
Will be described.

As shown in FIG. 2, this embodiment is a case where the number of diffuser vanes 8 closest to the discharge nozzle 6 is reduced to one half as compared with FIG.

As described above, by greatly reducing the number of vanes in the diffuser vane 8, the flow angle of the fluid in the diffuser vane 8 is inclined in the circumferential direction. However, this can be prevented by making the exit diameter of the vanes relatively larger than the other stages as represented by the following equation (3).

[0030]

(Equation 3)

Therefore, a decrease in diffuser efficiency can be minimized.

In the above embodiment, the case where one discharge nozzle is provided in one casing has been described. However, the present invention is not limited to this, and the case where two discharge nozzles are provided in one casing is described. Is also applicable. For example, when two suction ports are provided on both sides of one casing and two discharge nozzles are provided at the center, the inlet diameters of the two diffuser vanes closest to the two discharge nozzles are adjusted. The same effect as in the previous embodiment can be obtained by installing one or both of the two diffuser vanes outside the other diffuser vanes or greatly reducing the number of vanes of the two diffuser vanes. Having.

[0033]

According to the present invention, the power of the sound propagating to the discharge pipe of the multi-stage compressor can be reduced, so that the noise of the compressor can be reduced and the efficiency of the compressor can be substantially reduced. There is an effect that can be achieved without any reduction.

[Brief description of the drawings]

FIG. 1 is a model diagram showing a multi-stage centrifugal compressor according to a first embodiment of the present invention.

FIG. 2 is a view showing a diffuser vane according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a conventional multistage centrifugal compressor.

FIG. 4 is a view showing a conventional diffuser vane.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Casing, 2 ... Bearing, 3 ... Rotary shaft, 4 ... Impeller,
5 suction nozzle, 6 discharge nozzle, 7, 8 diffuser vane, 9 diffuser.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiromi Kobayashi 502, Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (56) References JP-B-38-14780 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04D 29/40-29/56 F04D 17/12

Claims (3)

(57) [Claims] 1. A casing having at least one suction nozzle and at least one discharge nozzle, a rotating shaft rotatably supported by the casing, and a plurality of impellers supported by the rotating shaft. Installed around the car,
A plurality of diffusers formed by two wall surfaces facing each other at an interval in the axial direction; and a diffuser installed on at least two or more of the plurality of diffusers, at least one of which is connected to the discharge nozzle. in multi-stage centrifugal compressor provided with vanes, closest to the discharge nozzle
The number of diffuser vanes to other diffuser vanes
Multi-stage centrifugal compressor characterized by having less than the number of sheets . A casing having at least one suction nozzle and at least one discharge nozzle, a rotating shaft rotatably supported by the casing, and a plurality of impellers supported by the rotating shaft. Installed around the car,
A plurality of diffusers formed by two wall surfaces facing each other at an interval in the axial direction; and a diffuser installed on at least two or more of the plurality of diffusers, at least one of which is connected to the discharge nozzle. in multi-stage centrifugal compressor provided with vanes, closest to the discharge nozzle
The inlet diameter of the diffuser vane to the other diffuser
We established outward from inlet diameter of Zaben, multistage centrifugal compressor, characterized in that the number of the de <br/> Ifuyuzaben less than the number of the other day fuser vane. 3. The multistage centrifugal pressure according to claim 1 or 2.
In the compressor, the diffuser closest to the discharge nozzle
-The exit diameter of the vanes is adjusted to the exit diameter of the other diffuser vanes.
Multistage centrifugation characterized by being relatively larger than the caliber
Compressor.