JPH0953593A - Shaft sealing device for rotary fluid machinery - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a shaft seal device for a rotating fluid machine, which can easily secure high reliability without separately providing an external device. [Structure] When the shaft 1 of a centrifugal compressor 50 rotates, the gas inside the seal impeller 3 is compressed radially outward by a centrifugal force. At this time, the suction portion 3A of the seal impeller 3 and the radial center portion of the shaft end surface 1A communicate with each other through the communication hole 2
The air 7 at the atmospheric pressure P _o , which is in the vicinity of the shaft end surface 1A, communicates with each other through the communication hole 2 and the seal impeller 3
After being pressurized to P _o + α which is higher than the atmospheric pressure, it is discharged from the seal 3 impeller outlet in the outer diameter direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal device provided in a rotary fluid machine such as a compressor or a blower,
In particular, to prevent leakage of internally handled gas to the outside, or
The present invention relates to a shaft seal device for a rotary fluid machine that prevents oil from entering from the bearing portion into the machine.

[0002]

2. Description of the Related Art Conventionally, there are the following two types of shaft seal devices for sealing the shafts of generally used compressors, blowers and the like.

(1) Oil film seal For example, API STANDARD 617 5th Ed
edition (1988) FIG. As disclosed in 5, by constantly supplying a seal oil having a pressure slightly higher than the pressure of gas to the float ring to form an oil film in a small gap between the shaft and the floating ring,
For example, the gas inside the aircraft is prevented from leaking to the outside. At this time, the seal oil is supplied by the seal oil head tank and the seal oil supply device. The seal oil head tank is located several meters higher than the installation location of the compressor, and the gas side is connected to the internal gas of the compressor. Hold it constant and seal the shaft. In addition, the seal oil refueling device is a reservoir pump
It consists of a cooler, filter, etc., and is installed separately from the compressor. Similarly, oil is discharged by a drainer unit provided separately from the compressor.

(2) Dry gas seal For example, API STANDARD 617 5th Ed
edition (1988) FIG. As disclosed in No. 7, buffer gas is constantly supplied to the seal portion to block, for example, in-machine gas from leaking to the outside. At this time, since the sealing surface has the property of not accepting even fine foreign matter, clean buffer gas that has passed through a special filter is used as the buffer gas, which is supplied from the utility including the control valve that controls the buffer gas pressure to the air It is supplied by a buffer gas supply unit having a function of supplying nitrogen and the like.

[0005]

However, the above prior art has the following problems. In the oil seal of (1), as described above, the seal oil refueling device, the seal oil head tank, the drainer unit, etc. must be separately installed as external devices. In order to ensure the reliability of the components of these units, regular maintenance is extremely important. Above all, the seal ring, which is the shaft seal part, requires extremely advanced technology to form an oil film in the gap with the shaft that rotates at high speed. There is a problem that it is not easy to secure the high reliability required. In addition, the provision of such units as described above causes an increase in cost, and there is a problem in securing an installation place for installing these units. further,
Since it is necessary to supply power to the constituent devices (motor, turbine, etc.) of these units, the operating cost is correspondingly increased.

In the dry gas seal (2), it is necessary to provide the buffer gas supply unit and the special filter as an external device in addition to the compressor. Also, in order not to damage the sealing surface of the dry gas seal, the filtration accuracy of the special filter must be made extremely fine, and careful attention must be paid when selecting the filter. Further, after the operation, it is necessary to constantly manage the differential pressure of the filter and replace the element when the differential pressure becomes large. Therefore, there is a problem that maintenance is very troublesome and the operating cost is high.

As described above, in any of the above cases (1) and (2), an external device unit for shaft sealing is required separately from the compressor.

An object of the present invention is to provide a shaft seal device for a rotary fluid machine which can easily ensure high reliability without separately providing an external device.

[0009]

In order to achieve the above object, according to the present invention, a rotary shaft, a blower / compression impeller fixed to the rotary shaft, and a bearing mechanism for supporting the rotary shaft. And a housing surrounding the periphery of the rotary fluid machine, which is provided in a rotary fluid machine, and seals the air blower / compression impeller side space and the bearing mechanism side space inside the housing. In the centrifugal shaft, a centrifugal sealing impeller fixed to a position of the rotating shaft on the side of the fan / compression impeller from the bearing mechanism, and a rotary shaft provided on the rotary shaft, one end of which has a diameter of an end surface of the rotary shaft. Provided is a shaft seal device for a rotary fluid machine, which has a communication hole which is opened at a substantially central portion in the direction and has the other end opened at the suction side of the sealing impeller. That.

Preferably, in the shaft sealing device of the rotary fluid machine, the pressure of air discharged from the outlet of the sealing impeller is, when the rotating shaft is rotated at a predetermined rotation speed, There is provided a shaft sealing device for a rotary fluid machine, wherein the shaft sealing device is configured so as to have a pressure higher than an internal gas pressure in the air blower / compression impeller side space inside the housing.

Preferably, in the shaft seal device of the rotary fluid machine, the shaft seal device is provided on the side of the fan / compression impeller of the housing, and guides at least a part of air discharged from the outlet of the seal impeller. A shaft seal device for a rotary fluid machine is provided, which is provided with a passage open to the atmosphere.

Further, preferably, in the shaft seal device of the rotary fluid machine, a labyrinth seal is provided in a portion of the housing facing the outlet of the sealing impeller, the shaft seal device of the rotary fluid machine. Will be provided.

[0013]

In the present invention configured as described above, when the rotary shaft of the rotary fluid machine rotates, the gas inside the sealing impeller is compressed radially outward by the centrifugal force. At this time, since the suction side of the sealing impeller and the substantially central portion in the radial direction of the end surface of the rotary shaft communicate with each other through the communication hole, the air at the atmospheric pressure P _{o in} the vicinity of the shaft end position inside the housing is After being pressurized to P _o + α higher than the atmospheric pressure in the sealing impeller through the communication holes, it is discharged from the sealing impeller outlet in the outer diameter direction. Here, since the inside of the space on the opposite side of the bearing mechanism (that is, the outside of the machine) of the inside of the housing is substantially equal to the atmospheric pressure P _o , at least a part of the air discharged from the sealing impeller outlet in the outer radial direction is , Will flow toward the bearing mechanism side space. Therefore, it is possible to block the minute oil mist / oil droplets generated in the bearing mechanism from flying into the space on the side of the impeller for blowing / compressing. Further, in advance, the impeller outlet pressure P _o + α at a predetermined rotation speed is set to be higher than the internal gas pressure P in the blower / compression impeller side (that is, inside the machine) space inside the housing. For example, outer diameter and outlet angle
If the outlet width and the number of stages are adjusted, the rest of the air discharged from the sealing impeller outlet in the outer diameter direction can flow toward the air blower / compression impeller side space. it can. With this configuration, the air discharged from the seal impeller outlet in the outer diameter direction flows separately into the air blow / compression impeller side space and the bearing mechanism side space, and the air blow / compression impeller side space and the bearing As a result of shutting off the space on the mechanism side, it is possible to prevent the internal handling gas of the rotary fluid machine such as the compressor or blower from leaking to the bearing mechanism side.
This is particularly effective when the gas handled internally has flammability and toxicity and cannot be leaked to the outside of the housing. On the other hand, when the handled gas is a harmless gas that can be released to the atmosphere, instead of the above structure, the passage that releases the air discharged from the seal impeller outlet to the atmosphere is provided with a blower / compressor for the housing. It may be provided on the side of the impeller, and the handling gas may be released to the atmosphere together with the air discharged in the outer diameter direction from the outlet of the sealing impeller. In this case, the atmospheric pressure P _o is interposed between the blower / compressor side space and the seal impeller outlet, so that the seal impeller outlet pressure P _o + α is set in the blower / compressor side space. Even if the pressure is not higher than P, it is possible to prevent backflow from the air blower / compressor side space to the sealing impeller. Therefore, there is an effect that the discharge pressure of the sealing impeller can be suppressed to the minimum necessary for sealing.

Further, a labyrinth seal is provided in a portion of the housing facing the outlet of the sealing impeller so that the air discharged from the outlet of the sealing impeller is blown.
It is possible to surely divide the flow into the compression impeller side space and the bearing mechanism side space, and it is possible to more effectively obtain the sealing action between the blower / compression impeller side space and the bearing mechanism side space.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. Each is an example of a shaft seal device for a single-shaft multi-stage centrifugal compressor when applied to a single-shaft multi-stage centrifugal compressor as an example of a rotary fluid machine. A first embodiment of the present invention will be described with reference to FIGS. This embodiment is an embodiment of a shaft seal device for a single-shaft multi-stage centrifugal compressor that uses a gas having flammability and toxicity as an internally handled gas.

FIG. 2 is a vertical sectional view of a single-shaft multi-stage centrifugal compressor 50 to which the shaft seal device 100 of this embodiment is applied. In FIG. 2, the centrifugal compressor 50 has a rotating shaft 1.
And a plurality of stages of impellers 10 fixed to the shaft 1.
And a bearing mechanism 11 that supports the rotary shaft 1 near both ends.
R and 11L, and a housing 12 surrounding them
And the shaft seal devices 100L and 100R according to the present embodiment provided near the bearing mechanisms 11R and 11L.

FIG. 1 shows an enlarged view of the portion A in FIG. 2 including the detailed structure of the shaft seal device 100R.

In FIG. 1, the shaft seal device 100R is
A seal impeller 3 fixed integrally with the shaft 1 between the inner space 6 inside the housing 12 of the compressor 50 and the bearing-side space 5, and one end provided in the shaft 1 whose center is the end surface 1A of the shaft 1. Is provided in the inside of the housing 12 (side plates on both sides of the seal impeller 3) at a portion facing the outlet of the seal impeller 3 and the communication hole 2 having the other end open to the suction portion 3A of the seal impeller 3. And a seal labyrinth 4. In the above configuration, when the shaft 1 of the centrifugal compressor 50 rotates, the gas inside the seal impeller 3 is compressed radially outward by the centrifugal force. At this time, since the suction portion 3A of the seal impeller 3 and the radial center portion of the shaft end surface 1A communicate with each other through the communication hole 2, the shaft end surface 1A is indicated by an arrow in FIG.
The air 7 having the atmospheric pressure P _o that was present in the vicinity is pressurized to P _o + α larger than the atmospheric pressure in the seal impeller 3 through the communication hole 2 and then discharged from the seal 3 impeller outlet in the outer diameter direction. To be done. Here, of the inside of the housing 12, the bearing mechanism 11R
Since the outer space 5 on the side is approximately equal to the atmospheric pressure P _o , a part of the air discharged from the outlet of the seal impeller 3 in the outer radial direction flows toward the outer space 5. Further, at this time, the seal impeller 3 has an outer diameter, an outlet angle, and an outlet in advance so that the seal impeller 3 outlet pressure P _o + α at a predetermined number of revolutions becomes higher than the internal gas pressure P in the machine interior space 6. The width has been adjusted. As a result, the remaining part of the air discharged in the outer diameter direction from the outlet of the seal impeller 3 flows toward the space 6 inside the machine. As described above, the air discharged from the outlet of the seal impeller 3 in the outer radial direction flows separately in the outer space 5 and the inner space 6, and at this position, the outer space 5 and the inner space 6 are separated. Since the gas is shut off, it is possible to prevent the flammable and toxic internal handling gas existing in the space 6 inside the machine from leaking to the bearing mechanism 11R side. Further, it is possible to block minute oil mist and oil droplets generated in the bearing mechanism 11R from flying into the space 6 inside the machine. Therefore, a high shaft seal can be achieved without separately providing conventional external equipment, that is, a seal oil supply device, a seal oil head tank, a drainer unit, etc. for an oil film seal, a special filter, a buffer gas supply unit, etc. for a dry gas seal. Reliability can be easily ensured. Therefore, the maintenance can be simplified and the installation area can be reduced, and the cost can be reduced.

The shaft seal device 100L provided on the opposite side has the same structure as the shaft seal device 100R.
It goes without saying that the same operational effect is achieved. Also,
In the above embodiment, the seal impeller 3 at a predetermined rotation speed is used.
The outlet pressure P _o + α depends on the impeller 10 inside the housing 12.
Although the outer diameter, the outlet angle, the outlet width, and the like are adjusted so as to be higher than the internal gas pressure P of the inner space 6 on the side, the number of stages may be further adjusted. That is, instead of the one-stage seal impeller 3 as shown in FIGS. 1 and 3, a plurality of stages of seal impeller may be provided. In this case, a similar effect is obtained.

A second embodiment of the present invention will be described with reference to FIGS. This embodiment is an embodiment of a shaft seal device for a single-shaft multi-stage centrifugal compressor that uses a non-toxic gas that can be released into the atmosphere as an internally handled gas. The same parts as those in the first embodiment are designated by the same reference numerals. The shaft seal device 200 of this embodiment
The configuration of the single-shaft multi-stage centrifugal compressor to which is applied is represented in FIG. 2 almost the same as that of the first embodiment except the shaft seal device portion, and therefore the description thereof is omitted.

The shaft seal device 20 of this embodiment provided near one bearing mechanism 11R of the single-shaft multi-stage centrifugal compressor.
FIG. 4 is a vertical sectional view showing the detailed structure of the 0R. FIG.
It is a figure corresponding to FIG. 1 of a 1st Example. In FIG. 4, the shaft seal device 200R of this embodiment is different from that of the first embodiment in that the seal impeller 3 is immediately inside the machine (on the left side in the drawing).
In addition, an atmospheric vent chamber 9 communicating with the atmospheric vent is provided across the labyrinth 8, and the outlet pressure P as described in the first embodiment in the configuration of the seal impeller 3 is provided.
_o + α is not particularly considered.
The other points are almost the same as the shaft seal device 100R of the first embodiment.

In the above structure, when the shaft 1 of the centrifugal compressor rotates, the gas inside the seal impeller 3 is compressed radially outward by the centrifugal force. At this time, since the suction portion 3A of the seal impeller 3 and the radial center portion of the shaft end surface 1A communicate with each other through the communication hole 2, FIG.
As indicated by an arrow, the air 7 at the atmospheric pressure P _{o in} the vicinity of the shaft end position inside the housing 12 passes through the communication hole 2 and is pressurized in the seal impeller 3 to P _o + α higher than the atmospheric pressure. Then, the seal 3 is discharged from the impeller outlet in the outer diameter direction.
Here, since the outboard space 5 on the bearing mechanism 11R side inside the housing 12 is substantially equal to the atmospheric pressure P _o , part of the air discharged from the outlet of the seal impeller 3 in the outer radial direction is part of the outboard space 5 It will flow toward. The remaining portion of the air discharged from the outlet of the seal impeller 3 in the outer diameter direction is guided to the atmosphere vent chamber 9 by the labyrinth 8.
Eventually, the atmosphere is released by an air vent (not shown). At this time, at the same time, the handling gas inside the compressor existing in the space 6 inside the machine merges with this flow and is released to the atmosphere (see the broken line arrow in the figure). As a result, the portion of the atmospheric pressure P _o is always present between the machine interior space 6 and the outlet of the seal impeller 3, so that the seal impeller 3 outlet pressure P _o + α is equal to the pressure P in the machine interior space 6. Even if it is not made higher, the handling gas is always released to the atmosphere from the atmosphere vent chamber 9, and the seal impeller 3
There is no backflow to. Therefore, there is an effect that the discharge pressure of the seal impeller 3 can be suppressed to the minimum necessary only for sealing.

Also according to this embodiment, the effect of preventing oil mist / oil droplets from the bearing mechanism 11R mechanism can be obtained as in the first embodiment. At this time, high shaft sealing reliability can be easily ensured without separately providing an external device as in the past, so that maintenance can be simplified and the installation area can be reduced, and the cost can be reduced. can do.

The shaft seal device 200L provided on the opposite side has the same structure as the shaft seal device 200R.
It goes without saying that the same operational effect is achieved. Also,
In FIG. 4, the seal impeller 3 is provided at substantially the same axial position as in FIG. 1 of the first embodiment. However, particularly in this embodiment, from the viewpoint of the oil mist block, the seal impeller 3 is provided immediately adjacent to the bearing mechanism 11. It is preferable to install them as close as possible.

[0025]

According to the present invention, the air discharged from the sealing impeller outlet in the outer radial direction flows separately in the blower / compression impeller side space and the bearing mechanism side space. It can block the generated minute oil mist and oil droplets from flying into the space on the side of the impeller for blowing and compression, and can prevent the internal handling gas of the compressor, blower, etc. from leaking to the bearing mechanism side. . Therefore, a high shaft seal can be achieved without separately providing conventional external equipment, that is, a seal oil supply device, a seal oil head tank, a drainer unit, etc. for an oil film seal, a special filter, a buffer gas supply unit, etc. for a dry gas seal. Reliability can be easily ensured. Therefore, the maintenance can be simplified and the installation area can be reduced, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a single-shaft multi-stage centrifugal compressor including a detailed structure of a shaft seal device according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the entire single-shaft multi-stage centrifugal compressor shown in FIG.

FIG. 3 is a diagram showing a behavior of a gas flow by the shaft sealing device shown in FIG.

FIG. 4 is a partial vertical cross-sectional view of a single-shaft multi-stage centrifugal compressor including a detailed structure of a shaft seal device according to a second embodiment of the present invention.

5 is a diagram showing a behavior of a gas flow by the shaft sealing device shown in FIG.

[Explanation of symbols]

 1 Shaft (Rotating Shaft) 1A End Surface 2 Communication Hole 3 Seal Impeller 3A Suction Part 4 Seal Labyrinth 5 Machine Outer Space 6 Machine Inner Space 7 Air 8 Labyrinth 9 Atmosphere Vent Chamber 10 Impeller (Blower / Compressor Impeller) 11L, R bearing mechanism 12 housing 50 single-axis multi-stage centrifugal compressor 100L, R-axis sealing device 200L, R-axis sealing device

Claims (4)

[Claims] 1. A rotary fluid machine provided with a rotary shaft, a blower / compression impeller fixed to the rotary shaft, a bearing mechanism for supporting the rotary shaft, and a housing surrounding these components. A shaft sealing device of a rotary fluid machine that seals the space between the blower / compression impeller inside the housing and the bearing mechanism side space, wherein the rotary shaft has a blower / compression impeller side from the bearing mechanism. A centrifugal sealing impeller fixed at the position of, and provided inside the rotary shaft, one end of which opens to a substantially central portion in the radial direction of the end surface of the rotary shaft, and the other end thereof,
A communication hole opened on the suction side of the sealing impeller,
A shaft seal device for a rotary fluid machine, comprising: 2. The shaft sealing device for a rotary fluid machine according to claim 1, wherein the sealing impeller is provided with air for discharging from the sealing impeller outlet when the rotating shaft is rotated at a predetermined rotation speed. A shaft seal device for a rotary fluid machine, wherein a pressure is configured to be higher than an internal gas pressure in the air blower / compression impeller side space inside the housing. 3. The shaft sealing device for a rotary fluid machine according to claim 1, wherein at least a part of air discharged from the outlet of the sealing impeller is provided on the side of the fan for compression / compression of the housing. A shaft seal device for a rotary fluid machine, comprising: a passage for guiding and opening to the atmosphere. 4. The shaft sealing device for a rotary fluid machine according to claim 1, wherein a labyrinth seal is provided at a portion of the housing facing the outlet of the sealing impeller. Sealing device.