JPH05997U - Seal gas supply mechanism for centrifugal compressors - Google Patents

Abstract

(57) [Abstract] [Purpose] To simplify the structure of the seal gas supply mechanism of a centrifugal compressor and shorten the length of the rotating shaft. [Structure] A rotary shaft 4 having an impeller 5 externally fitted to a tip portion projecting inward of a casing 1 is axially sealed and rotatably supported, and a seal housing 2 fixed to the casing 1 is provided with an impeller from the outside. By providing the seal gas supply base hole 2a communicating with the back chamber 5a and directly supplying the seal gas to the impeller back chamber 5a without passing through the labyrinth groove 9a of the seal ring 9, the structure of the seal gas supply mechanism is improved. On the other hand, since the thickness of the seal cage 7 can be reduced while simplifying it, the length of the rotary shaft 4 can be shortened by the amount corresponding to the reduction in the thickness of the seal cage 7.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a seal gas supply mechanism of a centrifugal compressor, and more particularly to a seal gas supply mechanism of a centrifugal compressor having a short seal gas supply hole and a simplified structure.

[0002]

[Prior Art]

 As is well known, single-stage centrifugal compressors have been conventionally used in polyethylene and polypropylene manufacturing equipment and other equipment. A seal oil supply mechanism that normally supplies seal oil to such centrifugal compressors. And a seal gas supply mechanism that supplies seal gas.

Hereinafter, a typical conventional example of the seal gas supply mechanism of the centrifugal compressor will be described with reference to FIGS. To explain with reference to FIG. 3 of the enlarged view, reference numeral 1 shown in FIG. 2 is a casing of a centrifugal compressor, and a through hole of the casing 1 is covered with a seal housing 2 and a flange thereof. It is fixed by a bolt B passed through a bolt hole provided in the section.

A shaft sealing mechanism 3 made of oil is internally provided in a through hole provided in the radial center of the seal housing 2, and a plurality of shaft sealing mechanisms 3 are provided at the radial center of the shaft sealing mechanism 3. The rotary shaft 4 is passed through a seal ring 9 around which a labyrinth groove 9a is provided.

[0005] hand which is rotatably supported by the rotary shaft 4 is seal housing 2 of the counter-casing side is provided inside a cylindrical bearing housing 6 which is fixed to the surface of formed of a plurality of bearings B _e, casing An impeller 5 having a well-known configuration is externally fitted to the tip end portion of the rotary shaft 4 which projects inward of the rotary shaft 1. It should be noted that what is externally fitted to the protruding end portion of the rotary shaft 4 from the bearing box 6 is a joint C for rotating the rotary shaft 4.

On the surface of the seal housing 2 facing the impeller 5, there is fixed a substantially disk-shaped seal cage 7 fitted onto the rotary shaft 4 via a seal ring 9. A ring-shaped groove is provided on the mating surface near the outer edge of the seal cage 7 of the seal housing 2, while the gas chamber 8 formed by the seal cage 7 and the ring-shaped groove is located outside the seal housing 2. A seal gas supply base hole 2a, which is opened obliquely from, communicates with the base hole 2a.

Further, the seal cage 7 has a seal ring 9 which is fitted around the outer peripheral surface of the seal ring 9 toward the fitting hole of the seal ring 9, that is, is fitted onto the rotary shaft 4 from the gas chamber 8 and rotates together. A seal gas supply destination hole 7a communicating with the labyrinth groove 9a on the outer periphery is formed.

Therefore, the seal gas supplied from the seal gas supply base hole 2a passes through the gas chamber 8, the seal gas supply destination hole 7a, and the labyrinth groove 9a, and then on the surface facing the seal cage 7 and the seal cage 7 of the impeller 5. Provided in the casing 1 through the labyrinth gap T between the inner peripheral surface of the seal housing 2 and the discharge side front end of the impeller 5 while entering the impeller back chamber 10 formed between the impeller back surface 5a. Since the compressed gas passage 1a is about to enter, the compressed gas is prevented from leaking.

[0009]

[Problems to be solved by the device]

 The shaft sealing means using the seal gas of the centrifugal compressor according to the above conventional example has no particular problem in terms of the sealing function, but it requires two supply holes, a seal gas supply base hole and a seal gas supply destination hole, a gas chamber, etc. Therefore, its structure becomes complicated.

In addition to the problem of the complexity of the structure, as described above, the seal cage needs to be provided with a seal gas supply hole, which increases the thickness, so that the rotating shaft must be lengthened. However, there was a problem to be solved that the rotor had to be designed disadvantageously in terms of rigidity.

Of course, if the rotating shaft has a large diameter, the rigidity problem of the rotor is solved, but as a result, the bearing for supporting the rotating shaft becomes larger and the bearing box becomes larger accordingly. Not only is it disadvantageous in terms of economy because the cost of the compressor increases, but there is also a problem in durability of the shaft sealing means due to an increase in the peripheral speed of the rotating shaft, which is not preferable.

[0012] Accordingly, an object of the present invention is to provide a seal gas supply mechanism for a centrifugal compressor, which has a simple structure of the seal gas supply mechanism and can have a shorter rotation shaft than conventional.

[0013]

[Means for Solving the Problems]

 The present invention solves the above-mentioned problems by focusing on the fact that the structure of the seal gas supply mechanism for supplying the seal gas is simplified if the seal gas supply base hole is directly communicated with the impeller back chamber. The structure of the seal gas supply mechanism of the centrifugal compressor according to the present invention is such that the rotor is fixed to the casing of the centrifugal compressor, and the impeller is externally fitted to the tip of the rotating shaft projecting inside the casing. In a seal gas supply device of a centrifugal compressor having a seal gas supply hole formed in a seal housing rotatably supported by a mechanism, the seal gas supply hole is provided from the outside of the seal housing. It is characterized by communicating with an impeller back chamber between the inner surface and the back surface of the impeller facing the inner surface.

[0014]

[Action]

 According to the seal gas supply mechanism of the centrifugal compressor according to the present invention, the seal housing is provided with the seal gas supply hole that communicates with the impeller rear chamber from the outside thereof. In addition to the simplification, the thickness of the seal cage fixed to the inner surface of the seal housing can be reduced, so that the rotating shaft can be shortened by the thickness of the seal cage.

Then, the seal gas supplied to the impeller rear chamber tries to enter the compressed gas passage provided in the seal housing through the labyrinth gap between the inner peripheral surface of the seal housing and the discharge side tip of the impeller. On the other hand, since the oil flows to the shaft sealing mechanism side, the shaft sealing function is not hindered.

[0016]

【Example】

 An embodiment of a seal gas supply mechanism for a centrifugal compressor according to the present invention will be described below with reference to FIG. Those having a function will be described with the same reference numerals.

Reference numeral 1 shown in FIG. 1 is a centrifugal compressor casing, and a seal housing 2 is fixed to the casing 1 so as to close a through hole provided in the casing 1. A shaft sealing mechanism 3 made of oil is internally provided in a through hole provided in the seal housing 2, and a rotary shaft 4 is passed through the radial center of the shaft sealing mechanism 3.

The rotating shaft 4 is rotatably supported by a cylindrical bearing box 6 fixed to the surface of the seal housing 2 on the side opposite to the casing, while at the tip of the casing 1 protruding inward. The impeller 5 having a well-known configuration is externally fitted.

The seal housing 2 has a surface facing the impeller 5 and a seal fitted on the rotary shaft 4 via a seal ring 9 having a labyrinth groove 9a formed around the rotary shaft 4. The cage 7 is fixed.

Further, from the outside of the seal housing 2, a seal gas is introduced into an impeller rear chamber 10 formed between the impeller rear surface 5 a of the impeller 5 facing the seal cage 7 and the seal cage 7. The supply base hole 2a is configured to communicate with each other.

Therefore, as in the conventional case, the seal gas supplied from the seal gas supply base hole 2a is directly supplied to the impeller rear chamber 10 without passing through the gas chamber, the seal gas supply destination hole and the labyrinth groove 9a, and the seal housing From the labyrinth gap T between the inner circumferential surface of 2 and the tip of the impeller 5 on the discharge side, the compressed gas passage 1a provided in the casing 1 is attempted to enter, so that leakage of the compressed gas is prevented while the labyrinth groove is formed. Since the oil flows into the 9a side, no adverse effect of oil on the shaft sealing mechanism 3 was observed, and the centrifugal compressor could continue its operation normally.

As described above, since only one seal gas supply base hole 2a is required, the structure thereof is extremely simple as compared with the conventional structure, and the seal cage 7 has a seal gas supply destination hole unlike the conventional structure. Since it is not necessary to provide the structure, the thickness thereof can be reduced. As a result, the length of the rotating shaft 4 can be shortened by the amount of the thinner seal cage 7, which is extremely advantageous in the design of the rotor.

Further, it is not necessary to incline the seal gas supply base hole 2a to communicate with a narrow gas chamber as in the conventional case, but it is sufficient that the seal gas supply base hole 2a communicates with the impeller rear chamber 10 only. As a result of being able to reduce the drilling precision of, the effect of reducing the drilling cost has also been derived.

[0024]

[Effect of the device]

 As described above in detail, according to the seal gas supply mechanism of the centrifugal compressor having the above-described structure according to the present invention, the seal gas is provided only with the seal gas supply hole communicating from the outside to the impeller rear chamber. The structure of the feeding mechanism is simplified, which is extremely advantageous for reducing the processing cost, and the rotating shaft can be shortened by the reduction of the thickness of the seal cage fixed to the inner surface of the seal housing. Therefore, it is extremely advantageous in terms of rotor design, and the reliability of the centrifugal compressor is improved due to the simplification of the structure of the seal gas supply mechanism.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural explanatory view of a main part of a centrifugal compressor according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a cross-sectional configuration of main parts of a centrifugal compressor according to a conventional example.

FIG. 3 is an enlarged view of part A of FIG.

[Explanation of symbols]

 1 ... Casing 1a ... Compressed gas passageway 2 ... Seal housing 2a ... Seal gas supply base hole 3 ... Shaft sealing mechanism 4 ... Rotating shaft 5 ... Impeller 5a ... Impeller back face 6 ... Bearing box 7 ... Seal cage 9 ... Seal ring 9a ... Labyrinth Groove 10 ... Impeller back chamber T ... Labyrinth gap

Claims (1)

Claims for utility model registration 1. A rotor, which is fixed to a casing of a centrifugal compressor and has an impeller externally fitted to the tip of a rotary shaft protruding inside the casing, through a shaft sealing mechanism. In a seal gas supply mechanism of a centrifugal compressor having a seal gas supply hole formed in a seal housing rotatably supported, the seal gas supply hole is provided from the outside of the seal housing to the inner surface of the seal housing and A seal gas supply mechanism for a centrifugal compressor, characterized in that the seal gas supply mechanism communicates with an impeller back chamber between the back surface of the impeller facing the inner surface.