JP2008303854A - Centrifugal compressor and method of operating centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal compressor increased in mechanical strength by suppressing the temperature rise of the impeller and having high reliability and a method of operating the centrifugal compressor. <P>SOLUTION: This centrifugal compressor S comprises: the impeller 1 formed by attaching a plurality of blades 3 to a rotating shaft 2 and guiding a gas by rotating the rotating shaft 2; and a housing 10 so installed as to surround the impeller 1 and having a shroud wall 12 extending in the upstream direction of the rotating shaft 2 and forming a gas suction port 14. An opening 20 is formed in the shroud wall 12 at the position corresponding to the middle part of the impeller 1, and liquid droplets are sprayed through the opening 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a centrifugal compressor and a method for operating the centrifugal compressor.

The centrifugal compressor is a compressor of a type in which the gas that has flowed in is deflected by 90 ° in the centrifugal direction of the rotation shaft of the impeller and the pressure is increased by a diffuser provided in the downstream portion of the impeller. Further, when a high pressure is required for the centrifugal compressor, a multistage type in which a large number of impellers are attached to one shaft is used.
In general, the centrifugal compressor is subjected to intermediate cooling for the purpose of improving efficiency and improving output regardless of the number of impellers. The following Patent Document 1 discloses a configuration in the case of performing intermediate cooling with a multistage centrifugal compressor. In this configuration, a cooling water injection nozzle is provided in the diffuser downstream of the impeller, and intermediate cooling is performed by injecting cooling water from this nozzle.
JP 2000-120595 A

  By the way, in the centrifugal compressor having the above-described configuration, the gas compressed by the diffuser becomes a high temperature, and the downstream side of the impeller is exposed to a high temperature, which causes the impeller to rise in temperature. However, in the configuration disclosed in the above document, since cooling water is injected into the diffuser downstream of the impeller, this cooling water does not contribute to lowering the temperature of the impeller described above. That is, in the above-described prior art, there is a possibility that the mechanical strength of the impeller is lowered due to the high temperature of the impeller, and the reliability is lowered.

  The present invention has been made in view of such circumstances, and improves the mechanical strength by suppressing the temperature rise of the impeller, and has a high reliability, and a method of operating the centrifugal compressor The purpose is to provide.

The present invention employs the following configuration in order to solve the above problems.
The centrifugal compressor of the present invention is provided with a plurality of blades on a rotating shaft, an impeller that guides gas when the rotating shaft rotates, and is provided so as to surround the impeller, and extends in the upstream direction of the rotating shaft, and And a housing including a shroud wall that forms a gas suction port, and an opening is formed at a position corresponding to a middle part of the impeller in the shroud wall, and droplets are generated from the opening. It is sprayed.

  In the centrifugal compressor, it is desirable that the opening is formed from the upstream side through which the gas flows toward the downstream side.

  In the centrifugal compressor, the shroud wall is formed in a substantially circular shape in a sectional view from the direction of the rotation axis, and the plurality of openings are evenly arranged along the circumferential direction of the shroud wall. It is desirable to be done.

  In the centrifugal compressor, it is desirable that the opening is formed in the shroud wall so as to follow the gas flow generated by the rotation of the blades.

  In the operation method of the centrifugal compressor of the present invention, the rotating shaft is provided with a plurality of blades, the impeller that guides the gas by rotating the rotating shaft, the surrounding impeller, and the upstream direction of the rotating shaft. A housing including a shroud wall extending to form the gas suction port, and a method of operating the centrifugal compressor, wherein the shroud wall is formed at a position facing a middle part of the blade during rotation of the impeller. The liquid droplets are sprayed from the formed opening.

According to the present invention, the following effects can be obtained.
During the gas flow process by the impeller, when the temperature of the gas rises, heat is taken away from the gas going downstream by the latent heat of vaporization when the spray droplets mixed in the gas evaporate. Temperature rise can be suppressed. Moreover, the droplet sprayed on the middle part of the impeller has a reduced speed with respect to the impeller blades. Further, since the droplets are refined by spraying, the blades are not damaged when the droplets are mixed in the gas, and so-called drain erosion is prevented. Therefore, the temperature rise of the impeller resulting from the compression process accompanying the gas flow process can be satisfactorily prevented, and the mechanical strength of the impeller is improved and high reliability is achieved.

  Hereinafter, the position embodiment of the centrifugal compressor of this invention and the operating method of a centrifugal compressor is demonstrated with reference to drawings. FIG. 1 is a cross-sectional view of a main part showing an embodiment of a centrifugal compressor of the present invention, FIG. 2 is a schematic perspective view of an impeller (impeller), and FIG. 3 shows an impeller and a shroud wall that accommodates the impeller It is the general | schematic cross-section block diagram seen from the rotating shaft direction.

  As shown in FIG. 1, the centrifugal compressor S includes an impeller (impeller) 1 and a housing 10 including a shroud wall 12 provided so as to surround the impeller 1.

  As shown in FIGS. 1 and 2, the impeller 1 includes a rotating shaft 2 provided to be rotatable around a predetermined axis O, and a plurality of radial arrangements based on the rotating shaft 2 (axis O). It has a blade 3. The impeller 1 provided with the blades 3 rotates around the axis O. A plurality of blades 3 are provided at equal intervals around the axis O (rotating shaft 2).

  As shown in FIG. 1, the shroud wall 12 is provided on the outer side with respect to the blade 3 of the impeller 1, and is formed so as to extend toward the upstream side in the axis O direction. The shroud wall 12 extends to the upstream side in the axis O direction to form a suction port 14. Further, on the downstream side of the housing 10, a diffuser portion 16 and a scroll-like compression flow path 17 connected to the diffuser portion 16 are formed.

  The impeller 1 is connected to a turbine impeller (not shown) via a shaft, and rotates via the shaft when the turbine impeller rotates due to exhaust of the engine. When the impeller 1 rotates, the intake air from the suction port 14 is compressed and drawn into the engine.

  A spray port (opening) 20 for spraying droplets toward the impeller 1 is formed at a position corresponding to the middle part of the blade 3 of the impeller 1 in the shroud wall 12. As shown in FIG. 3, the shroud wall 12 has a substantially circular shape when viewed in cross section, and is formed with a suction port for outside air (air) on the upstream side. As shown in FIG. 3, a plurality of the spray ports 20 are formed in the shroud wall 12, specifically, uniformly formed along the circumferential direction of the shroud wall 12. These spray ports 20 are formed from the upstream side through which the air flows toward the downstream side (see FIG. 1). The spray port 20 is formed so as to penetrate between the outer peripheral surface and the inner peripheral surface of the shroud wall 12, and the opening on the inner surface (impeller) side of the shroud wall 12 is in relation to the opening on the outer surface side. The rotational axis 2 is shifted in the rotational direction. Specifically, the spray port 20 is formed in the shroud wall 12 so as to follow the air flow generated by the rotation of the blade 3 in the impeller 1.

  In addition, it is desirable to use water as a droplet sprayed from the spraying port 20. The water sprayed from the spray port 20 is supplied from the outside of the centrifugal compressor S through a predetermined flow path. The water sprayed from the spray port 20 is configured to be supplied into the middle part of the blade 3, that is, the space 21 generated between the outer peripheral portion of the blade 3 and the shroud wall 12.

Next, an operation method of the centrifugal compressor S having the above-described configuration will be described.
The impeller 1 rotates around the axis O while air is sent from the suction port 14 toward the impeller 1. Here, with the rotation of the impeller, water is sprayed from the spray port 20 to a position corresponding to the middle part of the blade 3 of the impeller 1.

  That is, the sprayed moisture is contained in the outside air flowing in the space 21 generated between the outer peripheral portion of the blade 3 and the shroud wall 12. The outside air containing moisture is compressed by being sent to the diffuser portion 16 provided on the downstream side of the impeller 1 and the scroll-like compression flow path 17 connected to the diffuser portion 16 by the rotation of the impeller 1. In general, in a centrifugal compressor, outside air introduced from the outside rises from room temperature (about 20 ° C.) to 200 ° C. by a compression process.

  Here, when the impeller 1 formed by cutting an aluminum alloy is exposed to a high temperature such as the above-mentioned 200 ° C., there is a problem that the mechanical strength is lowered and the reliability is lowered.

  Therefore, in the centrifugal compressor S according to the present embodiment, the sprayed water droplets contained in the outside air evaporate along with the compression step. Then, it can suppress that the temperature in the downstream of the impeller 1 rises because heat is taken from external air by the evaporation latent heat of a droplet.

By the way, if the position where the droplets are sprayed is too upstream with respect to the impeller 1, there is a possibility that drain erosion will occur due to the droplets that have not been refined by spraying. Further, if the position where the droplets are sprayed is too downstream of the impeller 1, the temperature rise of the impeller 1 cannot be sufficiently suppressed.
Therefore, the position where the droplets are sprayed on the impeller 1 is important.

  The centrifugal compressor S according to the present embodiment employs a configuration in which droplets are sprayed on the middle part of the impeller 1. As a result, the droplet sprayed on the middle part of the blade 3 is suppressed in relative speed with respect to the blade 3, and the droplet formed in a spray form is very fine. Therefore, the vane 3 is not damaged by water drops during spraying, and so-called drain erosion can be prevented.

  Moreover, since the opening which comprises the said spraying port 20 is formed toward the downstream from the upstream, the centrifugal compressor S which concerns on this embodiment introduces the sprayed droplet smoothly to the flow in external air. And the above-described drain erosion can be better prevented.

  Further, the centrifugal compressor S according to the present embodiment is generated by the blades 3 of the impeller 1 by forming the spray ports 20 uniformly along the circumferential direction of the shroud wall 12 as shown in FIG. The droplets are sprayed substantially uniformly in the outside air flow path, and the cooling efficiency of the impeller 1 can be improved.

  Further, in the centrifugal compressor S according to the present embodiment, the spray port 20 is formed in the shroud wall 12 so as to follow the air flow generated by the rotation of the blades 3 in the impeller 1. The droplets sprayed on can be well combined with the flow of the outside air.

As described above, according to the centrifugal compressor S and the operation method thereof according to the present embodiment, the temperature of the sprayed water mixed in the outside air rises in the flow process of the outside air caused by the rotation of the impeller 1. As a result, the heat in the gas that is evaporated and is introduced downstream by this latent heat of vaporization can be taken away, whereby the temperature rise of the impeller 1 made of a material that is sensitive to high heat such as an aluminum alloy can be suppressed.
Further, the droplet sprayed on the middle part of the blade 3 has a relatively low speed with respect to the blade 3, and the sprayed droplet is very fine. Therefore, even when outside air mixed with droplets contacts the blade 3, the blade 3 is not damaged, and so-called drain erosion can be prevented. Therefore, it is possible to satisfactorily prevent an increase in the temperature of the impeller 1 due to the compression process associated with the flow process of the outside air, and to provide a highly reliable centrifugal compressor S by improving the mechanical strength of the impeller 1 as a result. Can do. In addition, since there is no restriction due to mechanical strength, the selection range of drive conditions is expanded.

  In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the meaning of this invention, it can change suitably. For example, in the above embodiment, a single-stage centrifugal compressor has been described. However, the present invention is also applicable to a multistage centrifugal compressor such as a two-stage centrifugal compressor.

It is principal part sectional drawing which shows schematic structure which concerns on one Embodiment of the centrifugal compressor of this invention. It is a schematic perspective view of an impeller. It is a schematic sectional drawing of the shroud wall which accommodates an impeller and an impeller.

Explanation of symbols

S ... centrifugal compressor, 1 ... impeller, 2 ... rotating shaft, 3 ... blade, 10 ... housing, 12 ... shroud wall, 20 ... spray port (opening)

Claims (5)

A plurality of blades are provided on the rotating shaft, an impeller that guides gas by rotating the rotating shaft, and a shroud that is provided so as to surround the impeller and extends in the upstream direction of the rotating shaft to form the gas suction port A centrifugal compressor comprising a housing including a wall;
A centrifugal compressor characterized in that an opening is formed at a position corresponding to the middle part of the impeller in the shroud wall, and droplets are sprayed from the opening.   The centrifugal compressor according to claim 1, wherein the opening is formed from an upstream side through which the gas flows toward a downstream side. The shroud wall is formed in a substantially circular shape in sectional view from the direction of the rotation axis,
The centrifugal compressor according to claim 1 or 2, wherein the plurality of openings are evenly arranged along a circumferential direction of the shroud wall.   The centrifugal compressor according to any one of claims 1 to 3, wherein the opening is formed in the shroud wall so as to follow the gas flow generated by the rotation of the blade. A plurality of blades are provided on the rotating shaft, an impeller that guides gas by rotating the rotating shaft, and a shroud that is provided so as to surround the impeller and extends in the upstream direction of the rotating shaft to form the gas suction port A housing including a wall, and a method of operating a centrifugal compressor comprising:
A method of operating a centrifugal compressor, wherein droplets are sprayed from an opening formed at a position of the shroud wall facing a middle part of the blade during rotation of the impeller.

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