JP3726005B2 - Multistage centrifugal compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multistage centrifugal compressor, and more particularly to a multistage centrifugal compressor casing thereof is horizontal split-type welding structure.
[0002]
[Prior art]
As for the fluid compressor in which the casing has a horizontal split type welded structure, for example, each of Japanese Patent Laid-Open Nos. 59-54800, 63-170591, 6-249199, 63-93406, etc. Examples disclosed in the publication are known. An example of a fluid compressor in which the outer casing is not a horizontal division type but the inner casing is a horizontal division type is disclosed in, for example, Japanese Patent Laid-Open No. 9-88864.
[0003]
[Problems to be solved by the invention]
The horizontal split type welded structure casing in a conventional fluid compressor as known in each of the above publications is a structure in which a half-cylindrical half-casing is usually joined horizontally at the top and bottom, that is, the joining surface is joined in a horizontal plane. Have As shown in FIG. 5 with a simplified general structure, the half casing has a semi-cylindrical body plate 1, and a horizontal joining flange 2 welded to each longitudinal side edge of the body plate 1. The side plate 3 is welded so as to close the left and right open portions of the body plate 1. Then, in the case of a horizontal split type welded structure casing obtained by horizontally joining the half-structured casing of the welded structure to which such a flange 2 is welded, for example, a multistage centrifugal compressor for gas compression, FIG. As shown in the example, a fluid flow path 4 is formed, and a rotating shaft 6 having a plurality of impellers 5 for compressing a working gas is incorporated, and a plurality of working gases flowing as indicated by an arrow A shown in the figure. Are sequentially pressurized by the impeller 5 and then discharged through the scroll 7. The flow path 4 is formed of an internal member such as a housing member 8, a housing member 9, and a diaphragm member 10 that are integrated, that is, not horizontally divided. The housing member 8 is assembled to the side plate 3 of the casing, functions to close the side end of the flow path 4, and supports the rotating shaft 6 via bearings 11a, 11b, and 11c assembled there. Is functioning.
[0004]
The inventors of the present application have examined the conventional fluid compressor having the above-described structure from various angles in order to further improve the airtightness and reduce the cost. As a result, it has been found that in the conventional structure, the flange 2 having an L-shape brings a limit to the airtightness and also increases the cost. The reason why the flange 2 is L-shaped in the conventional structure is related to the fact that the side plate 3 is provided in the casing and the housing member 8 for closing the side end portion of the flow path 4 is assembled to the side plate 3. Yes. That is, as the housing member 8 is assembled to the side plate 3, a sealing O-ring 12 is provided on the contact surface between the housing member 8 and the side plate 3. A sufficient tightening force is applied to the O-ring 12. In order to be able to add, the edge part of the flange 2 is extended along the side plate 3, and is made into the L-shape. That is, by making the end of the flange 2 L-shaped, the bolt hole 13 for bolt tightening in the flange 2 can be brought close to the O-ring 12, thereby increasing the tightening force for the O-ring 12. The airtightness is increased as much as possible.
[0005]
However, as shown in FIG. 6, in the conventional structure, even if the flange 2 is L-shaped, the relationship of interference with the housing member 8 or the like is such that the bolt hole 13 can be brought close to the O-ring 12. Naturally there is a limit. For this reason, when the pressure of the working fluid in the fluid compressor is higher than a certain level, it is difficult to obtain a sealing property that can withstand this. That is, even if the bolt hole 13 and the O-ring 12 are somewhat apart, it is not possible in principle to obtain the necessary sealing performance by increasing the bolt tightening force, but it is actually possible for the bolt. There are various strength limits that are difficult to do.
[0006]
In this way, in the conventional structure, although the flange 2 can be made L-shaped, the airtightness can be improved as such, but between the bolt hole 13 and the O-ring 12 in the L-shaped extending portion. This creates an unavoidable distance and this limits the level of sealing that can be achieved. Moreover, when the flange 2 is L-shaped, the yield of the material cut out from the flange 2 is deteriorated, which causes a cost increase. If the flange 2 is L-shaped, the weld line also becomes L-shaped when the flange 2 is welded to the body plate 1. Therefore, if the welding is performed only by the welding robot, the structure of the welding robot becomes very complicated. turn into. For this reason, in actuality, in addition to welding by the welding robot, manual welding is unavoidably performed, and this also increases the cost.
[0007]
The present invention has been made on the basis of the above-described knowledge, and aims to improve the structure that has been a cause of a decrease in airtightness and an increase in cost in a conventional fluid compressor.
[0008]
[Means for Solving the Problems]
A fluid flow path is formed by an internal member inside a cylindrical casing, and the casing includes a semi-cylindrical upper half casing and a lower half casing, respectively, welded with flanges for horizontal joining. In a multistage centrifugal compressor which is a horizontally divided welded structure casing formed by bolting via the flange, an end used for closing the left and right side ends of the flow path in the internal member the inner member for parts closed by contacting through the liquid gasket to the inner peripheral surface of the casing at its side, the seal of the side end portion on the contact surface between the inner peripheral surface side and the casing of the end closure for the inner member with interposing the O- ring use, the flange in close proximity to the installation position of the O- rings, are characterized by the formation of the liquid escaping recess for releasing the liquid gasket .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 partially shows the internal structure of a multistage centrifugal compressor having a horizontally divided type welded casing according to the first embodiment, and FIG. 2 shows the overall appearance of the casing. This embodiment is an example of a multistage centrifugal compressor for gas compression similar to the conventional one described above. Therefore, in the following description, the same reference numerals are given to the structural portions common to the conventional multistage centrifugal compressor described above, and the overlapping description is omitted as appropriate.
[0010]
As shown in FIG. 1, in the present invention, the radius of the housing member 20 corresponding to the housing member 8 in the conventional fluid compressor shown in FIG. 6 is made the same as the inner peripheral radius of the barrel plate 21 of the half casing. The side surface of the member 20 is brought into contact with the inner peripheral surface of the body plate 21. Therefore, the housing member 20 functions to close the side end portion of the flow path 4 while also serving as the side plate 3 in FIGS. 5 and 6 provided in the half casing of the conventional fluid compressor. . Further, as the housing member 20 is provided with such a structure, as shown in FIG. 2, the horizontal joining flange 22 in the half casing is formed linearly. An O-ring 23 is interposed on the contact surface between the side surface of the housing member 20 and the inner peripheral surface of the body plate 21, and the side end portion of the flow path 4 is sealed (air-tightened) by the O-ring 23. .
[0011]
As described above, the side surface of the housing member 20 is brought into direct contact with the inner peripheral surface of the body plate 21 of the half casing, and the O-ring 23 is provided there. The bolt hole 24 provided for fastening can be brought close to the O-ring 23 without restriction. As a result, it is possible to efficiently apply the bolting tightening force in the horizontal joining of the half casings to the O-ring 23 to increase the adhesion force, and to realize a higher sealing performance. Further, along with this, the flange 22 of the half casing can be made linear, and as a result, the yield of the material steel plate from which the flange 22 is cut can be improved, which enables cost reduction. Further, since the flange 22 is linear, the welding to the body plate 21 can be performed only by linear welding, so that the welding can be performed only by the welding robot, which also reduces the cost. Is possible.
[0012]
In the present invention, in addition to the structure as described above, the liquid escape recess 25 is provided in the flange 22 in the vicinity of the installation position of the O-ring 23. The reason why the liquid escape recess 25 is provided is as follows. There is a standard called API standard for the fluid compressor that is the subject of the present invention. This standard stipulates that solid packing (gasket. O-ring) should not be used to seal the flange joint surface in the casing of the horizontal split type welded structure. Therefore, liquid packing is used for the seal when the half casing is horizontally joined by bolting the flange 22. In this case, as described above, the side surface of the housing member 20 is brought into direct contact with the inner peripheral surface of the body plate 21 of the casing, and the O-ring 23 is interposed on the contact surface. There is a possibility that the liquid packing used on the surface is pushed out by the bolting pressure of the flange 22 and covers the periphery of the O-ring 23. If the liquid packing covers the periphery of the O-ring 23, the sealing performance by the O-ring 23 may be impaired. Therefore, a liquid escape recess 25 is provided in the flange 22 in the vicinity of the O-ring 23, and even if the liquid packing oozes from the joint surface of the flange 22 due to the bolting pressure, the O-ring escapes at the liquid escape recess 25. It is intended not to reach 23. In other words, by providing the liquid escape recess 25, the high sealing performance that can be achieved by efficiently transmitting the tightening force of the bolt tightening to the O-ring 23 as described above can be exhibited without damaging the liquid packing. It is what. In the example shown in the figure, the liquid escape recesses 25 are provided on both the left and right sides of the O-ring 23, but either one is sufficient for practical use.
[0013]
FIG. 3 partially shows the internal structure of the multistage centrifugal compressor according to the second embodiment. This embodiment is also an example of a multistage centrifugal compressor for gas compression, and is basically the same as that in the first embodiment. This embodiment is different from the first embodiment in that a holder member 26 that is an integral type and is not horizontally divided is joined along the outer periphery of the housing member 20 by welding or the like. The side surface, that is, the contact surface with the body plate 21 is made wider as a result, and the second O-ring 27 is provided on the widened side surface. By doing so, the sealing performance can be further enhanced.
[0014]
FIG. 4 shows an external structure of a multistage centrifugal compressor according to the third embodiment. This embodiment is also an example of a multistage centrifugal compressor for gas compression. The present embodiment is different from the above-described embodiments in that tightening with a plurality of bolts 28 is performed along the outer periphery of the body plate 21. That is, in the above embodiments, the bolting is performed only through the flange 22 of the half casing, whereas in this embodiment, the bolting is also performed on the outer periphery of the body plate 21. Bolt tightening via the body plate 21 is such that the bolt 28 is screwed into the housing member 20 in FIGS. 1 and 3 and the screwing position is along the O-ring 23. By doing in this way, a more uniform tightening force can be applied over the entire circumference of the O-ring 23, whereby the adhesion force of the O-ring 23 can be further increased, thus further improving the sealing performance. Can do. In FIG. 4, a suction nozzle 30 having a flange 29 at the tip is shown as an element not shown in FIGS. 1 to 3. The suction nozzle 29 is connected to a pipe (not shown) and functions to guide the working gas supplied therethrough into the machine.
[0015]
【The invention's effect】
As described above, in the present invention, the side surface of the housing member that functions to close the end portion on the flow path side is brought into contact with the inner peripheral surface of the casing via the liquid packing, and the side surface of the inner member for closing the end portion The O-ring for sealing the side end portion is interposed in the contact surface with the peripheral surface, and a liquid escape recess for releasing the liquid packing is formed in the flange close to the installation position of the O-ring. Even if the liquid packing oozes out from the joint surface of the flange due to the tightening pressure of the bolt, it can escape to the liquid escape recess, so that it does not reach the O-ring.
As a result, the tightening force of the bolt can be efficiently transmitted to the O-ring, so that the tightening force to the O-ring can be further increased, and hence the sealing performance can be improved. Moreover, the flange of a half casing can be made into a linear form, and this can improve a material yield, and can also simplify a manufacturing process.
[Brief description of the drawings]
FIG. 1 is a partial horizontal sectional view of a multistage centrifugal compressor according to a first embodiment.
FIG. 2 is a simplified external view of an upper half casing forming a casing in the multistage centrifugal compressor of FIG. 1;
FIG. 3 is a partial horizontal sectional view of a multistage centrifugal compressor according to a second embodiment.
FIG. 4 is a side view of a multistage centrifugal compressor according to a third embodiment.
FIG. 5 is a simplified external view of an upper half casing forming a casing in a conventional multistage centrifugal compressor.
FIG. 6 is a partial horizontal sectional view of a conventional multistage centrifugal compressor.
[Explanation of symbols]
4 Channel 20 Housing member (inner member for closing end)
21 Body plate 22 Horizontal joint flange 23 O-ring 24 Bolt hole 25 Liquid escape recess

Claims (1)

A fluid flow path is formed by an internal member inside a cylindrical casing, and the casing includes a semi-cylindrical upper half casing and a lower half casing, respectively, welded with flanges for horizontal joining. In a multistage centrifugal compressor which is a horizontally divided welded structure casing formed by bolting via the flange, an end used for closing the left and right side ends of the flow path in the internal member the inner member for parts closed by contacting through the liquid gasket to the inner peripheral surface of the casing at its side, the seal of the side end portion on the contact surface between the inner peripheral surface side and the casing of the end closure for the inner member with interposing the O- ring use, the flange in close proximity to the installation position of the O- rings, characterized in that the formation of the liquid escaping recess for releasing the liquid gasket multi Centrifugal compressor.

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