JP2918773B2 - 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 centrifugal compressor,
The present invention relates to a centrifugal compressor having a liquid injection nozzle suitable for enhancing the function of a compressor by directly injecting an evaporable liquid such as water into a gas stream, and relates to a cracked gas compressor for an ethylene plant, butadiene. It is used for process gas compressors for plants, compressors for various refrigeration cycles, air compressors, and the like.

[0002]

2. Description of the Related Art In a centrifugal gas compressor, it is known that wet compression in which an evaporable liquid is injected into a gas flow of the compressor to compress the liquid while evaporating the liquid is advantageous. For example, U.S. Pat.
Japanese Patent No. 34000 discloses a device provided with a liquid injection nozzle for the following purpose. Liquid is injected for the purpose of cleaning in order to prevent contamination such as mist and dust contained in the handling gas from adhering or accumulating in the gas flow path. The cleaning liquid is injected to prevent a part of the composition in the handling gas from forming sludge and adhering or depositing on the rotating or stationary body.

When sludge is likely to be formed as a part of the composition of the handled gas increases in temperature, liquid injection is performed so as to suppress the temperature increase of the gas by utilizing the vaporization of the liquid by injection of the liquid. The liquid is injected so as to reduce the power required for compression by lowering the temperature of the gas. During the refrigeration cycle, when the refrigerant is returned to the compression line in a liquid state and pressurized again, the liquid is injected so as to vaporize the liquid into gas in the compression system.

An example of a liquid injection nozzle will be described with reference to FIGS. FIG. 2 is a cross-sectional view of a main part of a conventional centrifugal compressor disclosed in U.S. Pat. No. 2,786,626, and FIG. 3 is a cross-sectional view of a main part of a conventional centrifugal compressor disclosed in Japanese Patent Publication No. 4-34000. It is. 2, reference numeral 1 denotes a first-stage impeller, 4 denotes a next-stage impeller, 6 denotes a diffuser which is a downstream portion of the impeller 1, and 7 denotes a gas flow from the diffuser 6 to the next-stage impeller 4. The return vane of the return flow path to be flowed into the diffuser vane, 8 is a diffuser vane, 10 is a rotating shaft, and C is the axis of the rotating shaft 1.

[0005] In the centrifugal compressor shown in FIG. 2, only one liquid injection nozzle 2 A is provided at a portion where the liquid is transferred from the diffuser 6 to the return vane 7. In this apparatus, it is difficult for the liquid injected from the liquid injection nozzle 2A to sufficiently create uniformity around the entire circumference.
There is a problem that the liquid cannot be sufficiently vaporized because the liquid flows immediately, and therefore the gas flow cannot be sufficiently cooled. In short, the path from the injection from the liquid injection nozzle 2A to the next stage impeller 4 is short, and it is not easy to raise the temperature, evaporate or mist, and the injection purpose cannot be sufficiently exhibited. Was.

As a technique for compensating for the above-mentioned drawbacks, a centrifugal compressor shown in FIG. 3 is known. 3, components having the same reference numerals as those in FIG. 2 indicate the same parts as those in the example of FIG. In the centrifugal compressor shown in FIG. 3, the liquid injection nozzle 2B is provided in the diffuser section 6, which is the outlet of the impeller 1, and is distributed over the entire circumference. To make up for the disadvantages. However, the invention shown in FIG. 3 is based on the premise that there is no diffuser vane, and is not preferable when there is a diffuser vane.

[0007]

It is well known that a diffuser vane is effective in improving fluid efficiency. Therefore, it is an object of the present invention to effectively perform liquid injection with a diffuser vane provided. The problems to be solved by the present invention will be specifically listed. (1) In order to make the injected liquid uniform over the entire circumference, it is effective to inject the liquid before the gas discharged from the impeller enters the diffuser vane. (2) The temperature of the next stage impeller is increased by compression, and the liquid injected from the liquid injection port passes through the liquid injected near the high temperature portion, which is the hottest portion near the impeller. It is heated while reaching the liquid injection nozzle, and the temperature rises.
Due to the temperature rise during this time, the injected liquid is easily vaporized in the gas passage.

(3) In order to achieve uniform liquid injection over the entire circumference, it is desirable that a plurality of liquid injection nozzles be arranged in a uniform distribution in the circumferential direction. (4) It is necessary to prevent the drain attack, erosion, and corrosion caused by the uniform distribution of the injection liquid in multiple directions, early vaporization, and collision with the liquid. (5) It is necessary to prevent vibration, erosion, and corrosion so that the liquid does not directly collide with the impeller, which is a rotating body, and comes into contact with the impeller.

In view of the above technical problems, an object of the present invention is to solve the problems of the prior art, to clean the inside, to reduce the temperature,
Injecting liquid into the compressor system to perform gas replenishment by filling in, etc., while ensuring uniformity of liquid injection throughout the circumference, and realizing a structure in which the liquid is easily vaporized quickly and easily. It is to provide a centrifugal compressor.

[0010]

Means for Solving the Problems In order to achieve the above object, and in particular, to uniformly supply the infusate over the entire circumference, the first invention according to the centrifugal compressor of the present invention comprises an inner casing. A rotating shaft supported by the rotating shaft, an impeller rotating with the rotating shaft constituting a plurality of compression stages disposed in the axial direction of the rotating shaft, and a diffuser vane serving as a downstream part of the impeller.
A centrifugal compressor having a diffuser having a flow path and a return flow path through which a gas flow from the diffuser flows into a next-stage impeller, and in which a vaporizable liquid is jetted into the gas flow path. A liquid injection nozzle for ejecting a possible liquid into a gas flow path is provided on a casing wall surface on a core plate side of at least one stage of an impeller.

Further, in order to achieve the above object, and particularly to make it easier for the injected liquid to be vaporized in the gas passage portion, the structure of the centrifugal compressor according to the second invention of the present invention is as follows. In addition to the configuration of the present invention, a liquid injection path for guiding the liquid to the liquid injection nozzle is arranged so as to pass near the outlet of the next stage impeller.

Further, in order to achieve the above object, and in particular, to uniformly supply the injection liquid to the entire circumference, the third invention according to the centrifugal compressor of the present invention comprises a liquid injection nozzle comprising: A plurality of these are arranged in the circumferential direction on the casing wall on the core plate side of the car .

[0013]

The operation of the above technical means will be described with reference to FIG. FIG. 4 is a sectional view of a main part showing a gas flow in a general multistage centrifugal compressor. The same reference numerals as in FIG. 2 and FIG. 1 described later denote the same parts in FIG. When the gas exits the impeller 1 and reaches the next-stage impeller 4, when the vaporizable liquid is to flow into the system, the liquid has uniformity over the entire circumference as much as possible and passes through a path as long as possible. In order to mix with the gas flowing in the main stream for a long period of time and to make contact with many passage surfaces, the position of the liquid injection nozzle is optimally the casing wall surface on the core plate side of the impeller.

As shown in FIG. 4, the main flow of the gas is (a)-(b)-(c)-(d) as indicated by white arrows, but the flow between the stage labyrinth 9 and the rotating body 10 is (E)-(f)-(g) shown by solid arrows as internal recycle flows flowing through the gaps. This (e)-(f)
In the present invention, the liquid injection nozzle 2 shown in FIG. 1 is provided on the wall surface of the casing on the core plate side of the impeller so as to perform the liquid injection along the flow of-(g). Before the liquid flows into the diffuser vanes 8, the main flow flowing out of the impeller 1 (b)
Will be mixed.

The purpose of injecting the liquid into the system was previously described in the section of the prior art as "-". In each case, after the liquid was injected, the liquid was in the form of a mist or a liquid. It is more effective to achieve the purpose of liquid injection if it is vaporized and gaseous at an early stage. During the liquid injection, it is natural that the pressure is increased on the liquid supply side so that the pressure becomes higher than the pressure at the part to be blown out. Heating and preheating are often not performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a main part of a multistage centrifugal compressor according to one embodiment of the present invention. Although FIG. 1 shows a single-stage impeller and a next-stage impeller, the number of stages is not limited in the present invention. In FIG. 1, reference numeral 1 denotes a first stage impeller, 1a denotes an impeller 1
And 1b are side plates of the impeller 1.

Reference numeral 2 denotes a liquid injection nozzle provided on the casing wall 13a on the core plate 1a side of the impeller, 3 denotes a liquid injection port, 4 denotes a next-stage impeller, 5 denotes a next-stage impeller diffuser wall, and 6 denotes a blade. A diffuser which is a downstream portion of the car 1 is a return vane of a return flow passage for allowing a gas flow from the diffuser 6 to flow into the next stage impeller 4, 8 is a diffuser vane, 9 is a stage labyrinth, 10 is a rotating shaft, C is the axis of the rotating shaft 10, 11 is a return corner of a return flow path for allowing the gas flow from the diffuser 6 to flow into the next stage impeller 4, 12
Is an impeller eye labyrinth.

The single-shaft multi-stage centrifugal compressor according to the present embodiment comprises a plurality of compression stages in the direction of the axis C of a rotating shaft 10 supported in a casing 13, and an impeller rotating with the rotating shaft 10. 1, a diffuser 6 that is a downstream part of the impeller 1, a return corner 11 for returning a gas flow from the diffuser 6 to the next-stage impeller 4, and a return vane 7, which can evaporate water or the like. A liquid injection nozzle 2 for ejecting a liquid into a gas flow path is provided on a casing wall 13a on the core plate 1a side of the impeller 1, and a liquid injection path for guiding the liquid to the liquid injection nozzle 2 is provided from the liquid injection port 3 to the next stage. It is provided so as to pass near the next stage impeller diffuser wall 5, which is near the exit of the impeller 4.

The liquid injection nozzle 2 is provided on the casing wall 1.
3a, a plurality are arranged in the circumferential direction. In FIG. 1, the liquid injection nozzles 2 and the liquid injection ports 3 have a single path, but the number of the liquid injection ports 3 may be the same for a plurality of liquid injection nozzles 2. Alternatively, the number of the liquid injection ports 3 may be set to be smaller than the number of the liquid injection nozzles 2.

The flow of the gas pressurized and discharged by the impeller 1 flows into the diffuser section 6, and the diffuser section 6 is provided with a diffuser vane 8. Next, the flow passes through the return corner 11 and flows into the return vane 7. The flow is rectified by the return vane 7 into an optimal flow for flowing into the next stage impeller 4. Further, the flow change at the stationary portion changes velocity energy into pressure energy.

FIG. 4 shows the flow of the gas by arrows. The main flow of gas flow is as shown by the white arrow (a)
-(B)-(c)-(d). When the pressure rises in the diffuser section 6 and the return vane 7, the internal flow passing through the stage labyrinth 9 is (E)-(F)-(G) as shown by the solid arrows. On the other hand, an internal flow (H)-(I) through the impeller eye labyrinth 12 occurs.

In this centrifugal compressor, liquid injection for the following purpose is performed. Liquid is injected for the purpose of cleaning in order to prevent mist, dust, and other stains contained in the handling gas from adhering or accumulating. The cleaning liquid is injected to prevent a part of the composition in the handling gas from forming sludge and adhering or depositing on the rotating or stationary body. When a part of the composition in the handled gas easily forms sludge as the temperature rises, the liquid is injected for the purpose of suppressing the temperature rise of the gas by utilizing the vaporization of the liquid.

Liquid is injected to reduce the power required for compression by lowering the temperature of the gas. During the refrigeration cycle, when the refrigerant is returned to the compression line in a liquid state and pressurized again, the liquid is injected so as to efficiently vaporize the liquid into gas in the compressor system. In any case, it is better that the liquid to be injected into the system is dispersed and injected throughout the flow, and is preheated to be as fine as possible a so-called mist, and to be easily vaporized. It is effective to achieve the purpose.

Since the flow of the gas flowing out of the impeller 1 is regulated by the dispenser vane 8 and the return vane 7, if the liquid is to be injected with uniformity all around,
If it is performed in this vane part, it is necessary to provide a liquid injection nozzle for each section regulated by the vane, and to perform injection of the same amount for each nozzle, including control to realize this,
A large amount of equipment is required.

The conventional examples are shown in FIGS. 2 and 3. However, since they are all injected into a section without vanes, no special control injection equipment is required. However, as described above as the prior art, in the case of FIG. 2, the passage route from the injection to the next stage impeller 4 is short, and it is not easy to raise the temperature, evaporate or fog, The purpose of liquid injection cannot be fully demonstrated. FIG. 3 improves this, but the idea is based on the assumption that there is no diffuser vane, and is not preferable when there is a diffuser vane.

In the present embodiment, the core plate 1a of the impeller 1
By injecting the liquid from the side wall casing wall 13a on the side, the injected liquid is scattered all around the side surface of the impeller 1 and becomes a mist, and flows to the diffuser section 6 and the return section with uniform uniformity around the entire circumference. This is effective because there is a flow riding on the internal flow (e)-(f)-(g) as shown in FIG.

The casing wall surface on the side plate 1b side is also located at the same position with respect to the impeller, but the flow on the side wall surface of the side plate 1b flows (h)-(i), and liquid is injected into this flow. Then, the liquid is injected into the impeller eye labyrinth 12, and the flow including the liquid in the narrow gap may cause not only erosion and corrosion but also vibration. Therefore, the side plate 1b side is not appropriate as a liquid injection place.

In the interior of the compressor, the outlet of the next stage impeller is always higher than the outlet temperature of the front stage impeller because it is compressed. Therefore, the liquid injected through the path passing close to the next-stage impeller diffuser wall surface 5 is preheated during this time, and the energy required for vaporization is given. Give me

Particularly, in this embodiment, the liquid injection nozzle 2
Since the plurality of impellers 1 are arranged in the circumferential direction on the casing wall surface 13a on the side of the core plate 1a, the uniformity of the liquid injection over the entire circumference is more effective. In addition, the tip of the injection section of the liquid injection nozzle 2 is set to have a nozzle shape such that the liquid to be sprayed is in a spray state, so that the liquid collides with the impeller 1 in a liquid state, so that drain attack, erosion, and corrosion are caused. Can be prevented.

Further, the exit direction of the liquid injection nozzle 2 is set so that the ejected droplet does not directly collide with the core plate 1a of the impeller 1, so that the liquid does not directly collide with the impeller, but forms a mist. Vibration, erosion, and corrosion can be more effectively prevented.

In the above embodiment, the liquid injection nozzle is
Although an example in which a plurality of impellers are provided in the circumferential direction on the casing wall surface on the core plate side of the one-stage impeller has been described, the present invention is not limited to this. For example, even if one is provided on the casing wall surface on the core plate side of the one-stage impeller, a corresponding effect can be obtained. Further, the liquid injection nozzle may be provided on the casing wall surface on the core plate side of the multi-stage impeller.

[0032]

As described above in detail, according to the present invention, when the liquid is injected into the compressor system in order to perform internal cleaning, temperature reduction, gas replenishment by filling, etc. A centrifugal compressor can be provided that realizes a structure in which the liquid is easily and easily vaporized early while ensuring the uniformity of the entire circumference. By making the injection site in the form of claims 1 to 3, the suction and injection device has uniformity over the entire circumference, is easy to vaporize, is simple, and is inexpensive.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a multistage centrifugal compressor according to one embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a conventional centrifugal compressor.

FIG. 3 is a sectional view of a main part of another conventional centrifugal compressor.

FIG. 4 is a sectional view of a main part showing a gas flow in a general multi-stage centrifugal compressor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Impeller, 1a ... Core plate, 2 ... Liquid injection nozzle, 3 ... Liquid injection port, 4 ... Next stage impeller, 5 ... Next stage impeller diffuser wall, 6 ... Diffuser part, 7 ... Return vane, 8 diffuser Vane, 10 ... shaft, 13 ... casing, 13a
... the casing wall.

Claims (3)

(57) [Claims] 1. A rotating shaft supported in a casing, an impeller rotating together with the rotating shaft, the impeller constituting a plurality of compression stages disposed in the axial direction of the rotating shaft, and a wake of the impeller. Centrifugal compression having a diffuser having a diffuser vane serving as a part and a return flow path for flowing a gas flow from the diffuser into a next stage impeller, and ejecting an evaporable liquid to the gas flow path. A centrifugal compressor, wherein a liquid injection nozzle for ejecting the evaporable liquid into a gas flow path is provided on a casing wall surface on a core plate side of at least one stage impeller. 2. The centrifugal compressor according to claim 1, wherein the liquid injection path for guiding the liquid to the liquid injection nozzle is arranged so as to pass near the outlet of the next stage impeller. 3. The centrifugal compressor according to claim 1, wherein a plurality of liquid injection nozzles are arranged in a circumferential direction on a casing wall surface on a core plate side of the impeller.