WO2008069142A1

WO2008069142A1 - Centrifugal compressor

Info

Publication number: WO2008069142A1
Application number: PCT/JP2007/073216
Authority: WO
Inventors: Tokiya Wakai; Shinji Iwamoto
Original assignee: Mitsubishi Heavy Industries, Ltd.
Priority date: 2006-12-01
Filing date: 2007-11-30
Publication date: 2008-06-12
Also published as: JP2008138577A; CN101523056B; CN101523056A; JP4980699B2

Abstract

When low-temperature gas (e.g. ethylene gas of up to -60°C) is to be compressed, heat shrinkage of a casing, especially heat shrinkage at one end (end on the side provided with a suction inlet) of the casing is absorbed to be able to prevent a reduction in clearance between a rotating shaft and a bearing (able to keep the clearance at a proper value (a specified value)), and thereby seizure at that portion (location) is prevented. A centrifugal compressor (10) provided with a casing which pivotally supports a rotating shaft (11) having a plurality of stages of impellers (12) via bearings (15, 22) and has a suction inlet for taking in work fluid at one end in the longitudinal direction of the rotating shaft (11), wherein at least one groove (23) extending along the longitudinal direction of the rotating shaft (11) is provided at one end of the casing (14b) and in a region positioned in a radial direction outer side of the bearings (15, 22).

Description

Specification

Centrifugal compressor

Technical field

The present invention relates to a centrifugal compressor, and particularly to a centrifugal compressor that compresses a low-temperature gas (for example, ethylene gas at 60 ° C. or lower).

Background art

[0002] As a centrifugal compressor, for example, the one disclosed in Patent Document 1 is known.

Patent Document 1: Japanese Patent Laid-Open No. 2001-3893

Disclosure of the invention

Problems to be solved by the invention

[0003] Now, when a low-temperature gas (for example, ethylene gas of 60 ° C or lower) is to be compressed using the centrifugal compressor disclosed in Patent Document 1 above, a casing (cabinet) ) In particular, heat shrinkage occurs at one end of the casing (the end with the suction port! /), Which reduces the clearance between the rotating shaft and the radial bearing ( The clearance could not be maintained at an appropriate value (predetermined value)), and there was a risk that seizure would occur at the location (location).

[0004] The present invention has been made in view of the above circumstances. When a low-temperature gas (for example, ethylene gas of 60 ° C or less) is compressed, the heat shrinkage of the passenger compartment, particularly the passenger compartment. The heat shrinkage at one end of the shaft (the end on the side equipped with the inlet) can be absorbed to prevent a decrease in the clearance between the rotating shaft and the bearing (clearance is an appropriate value (predetermined value)) It is a good idea to provide a centrifugal compressor that can prevent seizure at that location.

The present invention employs the following means in order to solve the above problems.

A centrifugal compressor according to the present invention includes a casing having a suction shaft for receiving a working fluid at one end in a longitudinal direction of the rotating shaft while bearing-supporting a rotating shaft having a plurality of impellers via a bearing. A centrifugal compressor having a longitudinal direction of the rotating shaft in a region located at an end of the casing and radially outside the bearing. At least one groove extending along the direction is provided.

[0006] According to such a centrifugal compressor, for example, when a low-temperature working fluid (for example, ethylene gas of 60 ° C or less) is compressed, the heat shrinkage of the casing, in particular, one end of the casing ( The heat shrinkage at the end of the side provided with the suction port is absorbed by the groove. That is, the thermal contraction of the casing due to the suction of the low-temperature working fluid is blocked by the groove.

As a result, it is possible to prevent the clearance between the rotating shaft and the bearing from decreasing (the clearance can be maintained at an appropriate value (predetermined value)), and the force to prevent seizure at the location (location). Monkey.

[0007] In the centrifugal compressor, it is more preferable that the bottom of the groove is formed to have a roundness.

Stress due to thermal contraction of the casing is concentrated on the bottom of the groove. However, since the bottom of the groove is formed to have a round shape (the R part), the stress concentrated on the bottom of the groove can be uniformly distributed in various directions, and cracks can be generated. Use force S to prevent the occurrence.

[0008] According to the present invention, when a low-temperature gas (for example, ethylene gas of 60 ° C or lower) is to be compressed, the thermal contraction of the passenger compartment, in particular, one end of the passenger compartment (including the inlet) The heat shrinkage at the end of the rotating shaft) can be absorbed to prevent the clearance between the rotating shaft and the bearing from decreasing (the clearance can be maintained at an appropriate value (predetermined value)). There is an effect that burn-in at a place can be prevented.

Brief Description of Drawings

FIG. 1 is a diagram showing an embodiment of a centrifugal compressor according to the present invention, and is a cross-sectional view showing an overall configuration of the centrifugal compressor.

FIG. 2 is a cross-sectional view taken along arrow II in FIG.

FIG. 3 is a front view taken along arrow A in FIG.

4 is a cross-sectional view taken along arrows IV-IV in FIG.

5 is an enlarged perspective view of a main part of the centrifugal compressor shown in FIG.

FIG. 6 is a diagram showing an embodiment of a centrifugal compressor according to the present invention, and is an enlarged view of a main part of the centrifugal compressor It is a perspective view.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a centrifugal compressor according to the present invention will be described with reference to FIGS. 1 to 5.

1 is a cross-sectional view showing the overall configuration of the centrifugal compressor according to the present embodiment, FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, and FIG. 3 is a front view taken along arrow A in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 2, and FIG. 5 is an enlarged perspective view of a main part of the centrifugal compressor according to the present embodiment.

As shown in FIG. 1, a centrifugal compressor 10 includes a plurality of stages (three stages in this embodiment) of an impeller 12 fixed to a shaft (rotating shaft) 11 and a diffuser 13 formed on the outer periphery of the impeller 12. A casing (cabinet) 14 and a journal bearing (bearing) 15 that seals between the casing 14 and the shaft 11 are provided.

The centrifugal compressor 10 according to the present embodiment is a horizontal axis type in which the shaft 11 is arranged in the horizontal direction, and is a horizontal division type in which the casing 14 is divided in the horizontal direction.

The centrifugal compressor 10 compresses and discharges gas (working fluid: for example, low temperature (60 ° C. or less) ethylene gas) g sucked from the suction port 16. In other words, the gas g that has also been sucked into the suction port 16 is given a centrifugal force by the rotation of the impeller 12 and is sent to the diffuser 13 at an increased speed and pressure, in response to changes in the flow passage area of the diffuser 13. Compressed. The gas g is further compressed every time it passes through each stage of the impeller 12, and is discharged from the discharge port 17 as a high-pressure gas.

The impeller 12 is a disk with a large number of blades attached thereto, and an impeller flow path 18 is formed between the blades. The gas g entering the impeller channel 18 from the center side is blown off by the rotation of the impeller 12, increases in speed and pressure, exits from the outer peripheral side, and is sent into the diffuser 13.

[0014] The diffuser 13 is a device that decelerates the gas g passing therethrough by changing the cross-sectional area of the flow path, and increases the pressure. The diffuser 13 causes the gas g flowing out of the impeller flow path 18 to flow into the subsequent impeller flow. A flow path that feeds the inlet of the path 18 is formed. Further, as shown in FIGS. 1 and 2, the diffuser 13 is provided with the impeller 12 connected in the axial direction, so that the force is directed radially outward from the outlet 19 of the impeller flow path 18. After bending at the outer periphery, It is formed so as to return inward and communicate with the inlet 20 of the impeller channel 18! /.

The shaft 11 that rotatably supports the impeller 12 is attached to the casing 14 with both ends supported by gas seals 21. One end of the shaft 11 (the left end in FIGS. 1 and 2) is also supported by a thrust bearing 22.

On the other hand, as shown in FIG. 1, the casing 14 includes an upper passenger compartment 14a and a lower passenger compartment 14b.

As shown in FIGS. 2 to 5, a slit (groove) 23 is provided in the lower compartment 14b of the centrifugal compressor 10 according to this embodiment. A total of two slits 23 are provided, one on each of the left and right sides of the lower passenger compartment 14b, on the radially outer side of the journal bearing (bearing) 15 located at one end of the shaft 11.

[0017] The dimension (size) of each slit 23 is, for example, the length (the length along the axial direction of the shaft 11) when the shaft diameter of the shaft 11 is 140 mm and the outer diameter of the housing 26 is 300 mm. ) L1 = 14 Omm, width (horizontal length) L2 = 40 mm, depth (vertical length) L3 = 170 mm.

In FIG. 1, FIG. 2, and FIG. 5, reference numeral 24 is a flow path for discharging lubricating oil, and reference numeral 25 in FIGS. 1 and 2 is a thrust collar. Further, when the depth L3 is set to 170 mm, a straight line connecting the tip (lower end) of the slit 23 in the vertical direction and the center axis (rotation axis) C of the shaft 11 and the upper surface of the lower passenger compartment 14b are formed. The angle is approximately 25 °. Further, the tip (bottom) of the slit 23 in the vertical direction is an R portion.

In the centrifugal compressor 10 according to the present embodiment, for example, when a low temperature gas (for example, ethylene gas of −60 ° C. or less) g is compressed, the thermal contraction of the lower passenger compartment 14b, particularly, The heat contraction force at one end of the chamber 14b (the end on the side provided with the suction port 16) is absorbed by the slit 23. That is, the heat shrinkage 1S slit 23 of the lower passenger compartment 14b by sucking in the low temperature gas is cut off.

As a result, it is possible to prevent the clearance between the shaft 11 and the journal bearing (bearing) 15 from being reduced (the clearance can be maintained at an appropriate value (predetermined value)), and at the place (location). Power S to prevent seizure.

[0020] Further, a stress due to thermal contraction of the lower passenger compartment 14b is applied to the front end of the slit 23 in the vertical direction. I will concentrate my power. However, since the tip end of the slit 23 in the vertical direction is the R portion, the stress concentrated on the tip end of the slit 23 in the vertical direction can be uniformly distributed in various directions, and cracks are generated. Can be prevented. In the unlikely event that a crack occurs at the tip of the slit 23 in the vertical direction, the crack will extend vertically downward. Do not disturb! /, (Do not affect me).

Furthermore, as shown in FIG. 5, the lubricating oil discharge channel 24 is formed so as to communicate only with the upper part of one end of the slit 23. That is, it is formed so as to draw a semicircular shape from one end to the other end of the locus force of the bottom surface of the flow path 24 for lubricating oil discharge.

As a result, it is possible to minimize the shaving of the lower passenger compartment 14b to form the flow path 24 for discharging the lubricating oil, and it is possible to sufficiently ensure the rigidity of the lower passenger compartment 14b.

[0022] Note that the present invention is not limited to the above-described embodiment, and may have a form as shown in FIG. In the present embodiment, the lubricating oil discharge flow path 24 a is formed so as to communicate with the entire one end of the slit 23. That is, the trajectory force on the bottom surface of the flow path 24a for discharging the lubricating oil is formed so as to draw a circular arc downward after traveling a predetermined distance in the direction approaching each other from both ends along the horizontal direction.

Thus, when compressing low-temperature gas (for example, ethylene gas of 60 ° C or lower) g, heat shrinkage of the lower passenger compartment 14b, particularly one end of the lower passenger compartment 14b (the side provided with the inlet 16) The thermal contraction at the end portion of the substrate can be absorbed more than that of the above-described embodiment. That is, the thermal contraction of the lower passenger compartment 14b caused by sucking in the low temperature gas can be blocked more than that in the above-described embodiment.

Accordingly, it is possible to further prevent the clearance between the shaft 11 and the journal bearing (bearing) 15 from being reduced (the clearance can be maintained at an appropriate value (predetermined value)), and seizure at the place (location) can be prevented. It can prevent more reliably.

Needless to say, the configuration shown in FIG. 6 can sufficiently secure the rigidity of the lower passenger compartment 14b.

Claims

The scope of the claims

[1] A centrifugal compressor provided with a casing having a suction port for taking in a working fluid at one end in the longitudinal direction of the rotating shaft while supporting the rotating shaft having a plurality of stages of impellers through a bearing. Because

A centrifugal compressor characterized in that at least one groove extending along a longitudinal direction of the rotating shaft is provided in a region located at one end portion of the casing and radially outside of the bearing.

[2] The centrifugal compressor according to [1], wherein the bottom of the groove is formed to be rounded.