JP2005351185A - Fluid compressor casing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the airtightness of a casing in a horizontally divided welded structure casing. In the conventional structure, the O-ring collapse allowance cannot be ensured uniformly over the entire circumference, and there is a fear that the airtightness of the casing cannot be maintained.
According to the present invention, by providing an O-ring at an outer peripheral corner portion on the casing side of an integrated holder, the crushing allowance of the O-ring can be made uniform and large in the radial direction. Therefore, it is possible to avoid the deterioration of workability due to an increase in the thickness of the casing body plate and an increase in the O-ring crushing amount, and to improve the airtightness of the casing.
[Selection] Figure 1

Description

  The present invention relates to an improvement in axial airtightness in a welded structure casing of a rotary machine such as a centrifugal compressor.

  In order to improve the airtightness of the horizontally divided welded structure casing of the conventional centrifugal compressor, it is necessary to apply a tightening force near the integrated side plate. For this reason, the upper and lower fastening flanges are also installed on the end face side of the integrated side plate in the axial direction, and the tightening force is directly applied by bolts, so that the O-rings on the outer periphery of the integrated side plate are in close contact with the casing to improve airtightness. It was. As a publicly known example of this, there is JP-B-1-33678.

  Also, in Japanese Patent Laid-Open No. 2001-254697, as a simplification of the horizontal split type welding structure casing structure, the half flange is straightened and the O-ring position is changed to the inner peripheral surface of the upper and lower fastening flanges. , To keep it airtight. Further, the airtightness is further increased by adding an integral holder.

JP-B-1-33678 JP 2001-254697 A

  In a conventional horizontal compressor type welding structure casing in a conventional fluid compressor as disclosed in Japanese Patent Application Laid-Open No. 2001-254697, a semi-cylindrical casing is horizontally joined vertically, that is, the joining surface is horizontal. It has a joined structure. As shown in FIG. 1, the half case is simplified by showing a general structure of the semi-cylindrical body plate 1 and a flange for upper and lower fastening welded in the longitudinal direction of the outer diameter portion of the body plate 1. 2, a body plate 1, and a side plate 3 fastened so as to close the left and right open portions of the body plate 1. Then, the half split casing of the welded structure in which such a flange 2 is welded is placed in the horizontally split welded structure casing, which is horizontally fastened by bolts at the top and bottom, for example, multistage centrifugal compression for a gas compressor. If it is a machine, a fluid passage 4 is formed by a compressor member, and a rotating shaft 6 having a plurality of impellers 5 for compressing a working gas is incorporated, and the working gas flows as shown by an arrow A in the figure. Are sequentially pressurized by a plurality of impellers 5 and then discharged through a scroll 7. The flow path 4 is an integral type, that is, formed by internal members such as the integral side plate member 3, the housing member 9, and the diaphragm member 10 that are not horizontally divided. The integrated side plate member 3 is assembled to the casing body plate 1 and functions to close the side end portion of the flow path 4 and is rotated via bearings 11a and 11b assembled there. It functions to support the shaft 6. The rotary shaft 6 is driven by a motor, a transmission, a steam turbine, a gas turbine, and the like via a shaft coupling 12.

  In the horizontally divided casing disclosed in Japanese Patent Laid-Open No. 2001-254697, an O-ring 21a is installed on the outer peripheral surface of the integrated side plate member 3 and the inner peripheral surface of the body plate 1 as shown in FIG. This is because the welding structure of the horizontal split type welding structure casing has been simplified and the material and processing costs have been reduced. At the same time, the position of the O-ring 21a is brought as close as possible to the bolt tightening position 24 to The tightening force is directly applied to the O-ring 21a to improve the airtightness. This attempted to prevent fluid leakage from the axial direction. However, in this structure, the O-ring 21a receives the weight of the integrated housing, and the O-ring 21a is pulled in the vertical direction to extend locally. There will be a difference. At the same time, there arises a problem that the O-ring 21a itself is damaged at the inner peripheral corner portion of the upper and lower fastening flange 2. Further, since the body plate 1 is not a structure that is restrained in the radial direction, there is a problem that the radial direction rigidity of the body plate 1 is low. There is also a problem that the residual stress during welding and the residual stress during machining are slightly changed. Due to these problems, the crushing allowance of the O-ring 21a cannot be ensured uniformly over the entire circumference, and the hermeticity of the casing may be lowered.

  Therefore, an integrated holder-14 that is not horizontally divided is installed on the outer peripheral end surface of the integrated side plate member 3, and the contact surface between the end surface of the integrated side plate member 3 and the inner peripheral surface of the body plate is widened by this integrated holder-14. In addition, there is a method of improving the airtightness by providing the O-ring 21b on the outer peripheral end face of the integrated side plate member 3, but this method contributes to the improvement of the airtightness on the inner diameter side of the outer peripheral end face of the integrated side plate member 3. However, it does not contribute to airtightness in the longitudinal direction of the outer diameter. This is because the O-ring 21b does not receive the weight of the integrated side plate member 3, and the deformation of the O-ring 21b is uniform, but the deformation of the body plate 1 is not considered. Because.

  In general, a centrifugal compressor for a process uses a toxic or flammable working fluid as a working fluid. Therefore, maintaining airtightness is an absolute requirement for the casing.

  The present invention has been made to solve the above-described problems, and is intended to improve airtightness in a conventional fluid compressor.

  In the present invention, the fluid flow path is formed by an internal member inside the cylindrical casing, and the upper and lower fastening flanges are welded to the semi-cylindrical body plate, and the semi-cylindrical upper divided casing is formed. -In a horizontally divided welded structure casing in which a single and a lower divided casing are bolted at the flange portion for upper and lower fastening, and fitted to the inner surface of the inner surface of the body plate and fixed to the end surface of the body plate An integrated holder that is in contact with the outer end face side of the end closing member used for closing the right and left end parts fixed in the axial direction with the bolt and bolt, the inner periphery of the shell plate, and the end face of the shell plate through the O-ring. It is characterized in that an O-ring is provided at the outer peripheral corner of the casing of the integrated holder.

  According to the present invention, an O-ring is provided at the corner on the casing side of the integral holder, and a contact surface is provided at the same time in the radial direction and the end face direction of the body plate. It is possible to improve the performance. As a result, it is possible to avoid deterioration of workability due to an increase in the thickness of the casing body plate and an increase in the O-ring collapse allowance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 partially shows the internal structure of a fluid compressor having a horizontally divided welding structure casing according to the first embodiment, and FIG. 2 shows the overall appearance of the casing. FIG. 3 shows an embodiment of the present invention, a partially enlarged view of FIG. 1, and FIG. 4 shows a conventional structure with respect to FIG. These figures are examples of a multistage centrifugal compressor of a process gas compressor. Therefore, in the following description, the overlapping description of the structural parts common to the multistage centrifugal compressor described above is omitted as appropriate.

  A representative embodiment is shown in FIG. FIG. 1 is a partial schematic cross-sectional view of a horizontally divided welded structure casing of a multistage centrifugal compressor. The integral side plate member 3 for closing the end portion is fitted to the inner peripheral portion of the body plate 1 and fixed in the radial direction, and the end surface of the inner peripheral portion of the body plate 1 is connected to the body plate via a plate 13 and a bolt. Fixed to the torso. In the initial state where no gas pressure acts on the inner side of the horizontally divided welded structure casing, the bearing 11a fixed to this member is secured by ensuring the perpendicularity of the end closing integral side plate member with respect to the shaft core, 11b, the shaft seal 8 and the like can be incorporated with high precision, and at the same time, when the gas pressure is applied to the inside, the end closing integrated side plate member 3 comes into abrupt contact with the inner peripheral end surface of the body plate. There is an effect to avoid that. The axial contact surface with the end closing integral side plate member 3 and the thickness thereof must be strong enough to withstand the total gas pressure acting on the end closing integral side plate member. An integrated holder-14 that contacts the outer end surface of the integrated side plate member 3 for closing the end portion, the inner peripheral surface of the body plate 1, and the end surface of the body plate 1 through O-rings 21 c and 21 d is provided. A contact surface is provided at the same time in the radial direction and the end face direction of the body plate 1 by an O-ring 21d at an outer peripheral corner portion of the 14 casing side, thereby providing end airtightness of the horizontally divided welded structure casing. Although it is difficult to bring the integrated holder 14 into contact with the two end surfaces at the same time, the dimensional tolerance can be allowed by the collapse amount of the O-ring through the O-rings 21c and 21d.

  In order to cope with the deformation of the inner peripheral portion of the body plate of the horizontally divided welded structure casing, there is a method of increasing the radial rigidity of the body plate 1 to minimize the deformation amount or reducing the stress during processing. However, increasing the radial rigidity of the trunk plate 1 leads to an increase in material thickness due to an increase in the thickness of the trunk plate 1 and welding with the integrated side plate member 3 for closing the end portion. It is not preferable to reduce the length because light cutting is performed and the processing time is increased.

  On the other hand, there is a method of positively increasing the crushing allowance of the O-ring 21e on the outer periphery of the integrated holder-14. At the same time, the airtightness is deteriorated due to the damage caused by the biting of the O-ring 21e. On the other hand, providing the O-ring 21d at the corner portion results in that the O-ring 21d is in contact with the end face of the body plate and the O-ring 21d is crushed in the axial direction without taking a large crushing margin in the radial direction. The deformation leads to an increase in the radial crushing margin, resulting in an improvement in airtightness.

  In FIG. 3, the O-ring 21e is also used in the outer periphery of the integrated holder, but basically the O-ring 21e is not required in the outer periphery.

  As a result of the above, it is possible to eliminate the conventionally used end-closing side plate member outer periphery O-ring 21a, and the liquid used for the horizontal dividing surface processed to maintain the airtightness of the O-ring. There is no need for incidental processing such as the recess 22 for storing the packing liquid. This liquid packing recess 22 is defined by the API standard for the fluid compressor that is the subject of the present invention that solid packing should not be used for the horizontal dividing surface. The end closing housing member outer periphery O-ring 21a is provided in order to avoid a decrease in airtightness due to covering.

  The horizontal split type welded structure casing has been described so far, but the present invention has the same effect on the airtightness of the left and right end portions of the integral cylindrical trunk type welded structure casing without horizontal split.

The partial horizontal sectional view of the multi stage centrifugal compressor by a 1st embodiment. The simplified external view of the casing in the multistage centrifugal compressor of FIG. The elements on larger scale of FIG. The elements on larger scale corresponding to FIG. 3 in the conventional structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Body plate, 2 ... Half flange, 3 ... Integrated side plate member, 4 ... Gas flow path, 5 ... Impeller, 6 ... Shaft, 7 ... Scroll, 8 ... Shaft seal, 9 ... Housing member, DESCRIPTION OF SYMBOLS 10 ... Diaphragm member, 11a ... Journal bearing, 11b ... Thrust bearing, 12 ... Joint, 13 ... Plate, 14 ... Integrated holder, 21a, bcde ... O-ring, 22 ... Recessed part for liquid reservoir, A ... direction of gas flow.

Claims (2)

  In a horizontally divided welded structure casing having a split surface on a horizontal plane, the welded structure casing has an integrated side plate that is separated from the casing main body, and has no upper and lower clamping portions on its end surface. The welded structure casing is characterized in that airtightness is enhanced by providing an O-ring at the corner of the casing side end face of the integrated holder. Welding characterized in that it is a cylindrical welded structure casing that does not have a split surface on a horizontal plane, and has improved airtightness by providing an O-ring at the corner of the casing-side end surface of the integrated holder portion that is separately mounted. Structural casing.

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