JP2000329097A - Shaft seal device for turbo type compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent process gas from leaking to the atmosphere by arranging a blow-by preventing fin which is projected outward of a radial direction from a sleeve disposed on a shaft side and for stopping flow of process gas between a process side labyrinth and an intermediate labyrinth, on an exhaust port for returning purge gas to a process side. SOLUTION: Since air supply pressure of a purge gas supplied from an air supply port 4 through an air supply port 12 is controlled so as to set slightly higher than an exhaust port 5, process gas is prevented from leaking to the atmosphere. When an abnormal situation is generated in this condition and process gas becomes high pressure, a blow-by phenomenon of process gas is generated, and areas of a process side labyrinth 7 and an intermediate labyrinth 8 are cut off by a blow-by preventing fin 10 arranged on a position of an exhaust port 5 and formed on a sleeve 2 attached to a rotary shaft 1, and the process side labyrinth 7 formed on a seal housing 6 side, and thereby, blow-by of process gas toward the atmosphere is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft sealing device for a turbo type compressor which handles highly toxic special gas such as chlorine gas.

[0002]

2. Description of the Related Art An outline of a conventional shaft sealing device for a turbo type compressor will be described with reference to FIG.

A rotary shaft 1 has a sleeve 2 fitted on the rotary shaft 1 and a Teflon ring 3 disposed on the outer periphery of the sleeve 2. The Teflon ring 3 has an exhaust port 5 connected to an exhaust port 11 and a supply port. An air supply port 4 connected to the air port 12 is provided on the process side and the atmosphere side separately from each other.

The Teflon ring 3 has a process side labyrinth 7 on the process side from the exhaust port 5, and a supply port 4.
An intermediate labyrinth 8 is arranged between the air lane 9 and the exhaust port 5, and an atmosphere labyrinth 9 is arranged on the atmosphere side from the air supply port 4. The three labyrinths and the sleeve 2 constitute a shaft sealing portion.

[0005] Reference numeral 6 denotes a seal housing which is arranged on the outer periphery of the Teflon ring 3 and holds the Teflon ring 3 at a predetermined position. Each of the process-side labyrinth 7, the intermediate labyrinth 8 and the atmosphere-side labyrinth 9 is made of a Teflon material integrally with the Teflon ring 3, and faces each of these labyrinths and cooperates with each other. The sleeve 2 forming the sealing portion is made of stainless steel.

In the conventional apparatus configured as described above, in a steady state, dry nitrogen is supplied as a purge gas from the air supply port 12 and its pressure is controlled to be slightly higher than the pressure of the exhaust port 11 communicating with the process side. Have been.

Therefore, when viewed from the shaft seal formed by the intermediate labyrinth 8 between the supply port 4 and the exhaust port 5, the process gas flowing into the exhaust port 5 is suppressed by the purge gas supplied to the supply port 4. The exhaust port 11 does not enter the shaft sealing portion formed by the intermediate labyrinth 8.
Through the process.

However, when the pressure on the process side becomes high due to the occurrence of an abnormal situation, the differential pressure between the exhaust port and the process side becomes large, so that the flow of the process gas leaked from the labyrinth provided therebetween becomes large. Since the pressure does not decrease and the process gas leaked from the labyrinth passes through the intermediate labyrinth 8 and reaches the air supply port 4 as shown by the solid arrow a in the figure, it further passes through the atmosphere-side labyrinth 9 and is broken This causes a so-called blow-by phenomenon in which the gas leaks into the atmosphere with the purge gas indicated by the arrow b.

In order to cope with this blow-by phenomenon, it is conceivable to increase the number of stages of the labyrinth on the process side or to increase the pressure of the purge gas from the gas supply port 12 to prevent blow-through. In the former measure, the number of stages of the labyrinth increases, so the length of the overhang portion of the rotating shaft 1 becomes longer, causing a problem in the stability of the rotating shaft 1. In the latter measure, the pressure of the air supply port 12 is increased. In this case, an excessive amount of purge gas is required to perform the process, and none of the solutions has been a drastic solution.

[0010] Further, since the seal casing defining the entire shaft sealing device is an integral cylinder, it is necessary to assemble the labyrinth unit while passing the rotary shaft 1 through the cylinder when attaching the seal casing. So
At this time, since the labyrinths 7, 8, and 9 are made of Teflon, there is also a problem that if the tip of the labyrinth hits the shaft side during assembly, the tip of the labyrinth is bent and the performance of the labyrinth is deteriorated. Was.

Furthermore, since the Teflon material is soft, processing specifications such as temperature conditions are strictly controlled when processing labyrinth fins, but as a result, there is a problem that processing accuracy is poor.

[0012]

A conventional apparatus of this kind is:
As described above, the occurrence of a blow-by phenomenon in which the process gas leaks to the atmosphere beyond the intermediate labyrinth during operation,
Various problems such as a problem that the point of the labyrinth bends during assembly and a problem that the processing accuracy deteriorates due to the material of the labyrinth fin during processing.

The present invention eliminates the disadvantages of the conventional shaft sealing device, prevents the process gas from bleeding into the atmosphere, and furthermore does not damage the point of the labyrinth. Another object of the present invention is to provide a turbo-sealed compressor shaft sealing device that improves the processing accuracy of labyrinth fins.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an air supply port and a process for supplying a purge gas to a Teflon ring disposed on the outer periphery of a sleeve fitted on a rotating shaft. An exhaust port to return to the air side is provided in the axial direction between the atmosphere side and the process side in the axial direction, the atmosphere side labyrinth is provided in the shaft seal part on the atmosphere side from the air supply port, and the intermediate labyrinth is provided in the shaft seal part between the air supply port and the exhaust port. In a shaft sealing device in which a process side labyrinth is disposed in a shaft sealing portion on a process side from an exhaust port, the exhaust port has a process side labyrinth that projects radially outward from a sleeve disposed on the shaft side. An object of the present invention is to provide a shaft sealing device of a turbo type compressor provided with blow-through prevention fins that block a flow of a process gas between intermediate labyrinths.

That is, according to the present invention, of the exhaust port and the supply port which are provided in the axial direction on the process side and the atmospheric side, the exhaust port is provided radially outward from the sleeve disposed on the axial side. The blow-through prevention fins are provided so as to protrude in the direction of the arrow. This is to prevent the phenomenon from occurring.

Further, according to the present invention, an atmosphere-side labyrinth provided in a shaft sealing portion on the atmosphere side from the air supply port, and an intermediate labyrinth provided in a shaft sealing portion between the air supply port and the exhaust port,
An object of the present invention is to provide a shaft sealing device of a turbo type compressor constituted by a metal labyrinth provided on an outer surface of the sleeve.

That is, according to the present invention, the atmosphere labyrinth provided on the atmosphere side from the air supply port, the intermediate labyrinth provided between the air supply port and the exhaust port, and the process side labyrinth provided on the process side from the exhaust port. Of these, the labyrinth on the atmosphere side and the intermediate labyrinth are composed of metal labyrinths, so the strength of these metal labyrinths is high, and the tip of the labyrinth is not damaged even if it comes into contact with other parts during assembly In addition, the processing accuracy of the labyrinth fin is improved due to the strength of the metal, and a more preferable shaft sealing device of a turbo type compressor is obtained in combination with prevention of occurrence of the blow-by phenomenon. is there.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. In order to avoid redundant description, the same parts as those of the above-described conventional apparatus are denoted by the same reference numerals in the drawings, and redundant description will be omitted. Let's focus on it.

That is, in the present embodiment, the process port blows through the exhaust port 5 between the process-side labyrinth 7 and the intermediate labyrinth 8 from the sleeve 2 disposed on the rotary shaft 1 outward in the radial direction. The prevention fin 10 is attached.

An atmosphere-side labyrinth 9 forming a shaft sealing portion on the atmosphere side from the air supply port 4 and an intermediate labyrinth 8 forming a shaft sealing portion between the air supply port 4 and the exhaust port 5 are formed of the sleeve 2. It is composed of a metal labyrinth provided on the outer surface.

The atmosphere-side labyrinth 9 and the intermediate labyrinth 8 may be formed integrally with the sleeve 2.
For this reason, the sleeve 2 is made of the same material as that of the sleeve 2. Usually, a stainless steel material is used. Alternatively, a metal material such as an inconel material or a chromium-molybdenum material may be used.

On the other hand, a process-side labyrinth 7 which forms a shaft sealing portion on the process side from the exhaust port 5 surrounds the atmosphere-side labyrinth 9 and the intermediate labyrinth 8 and surrounds the air-supply port 4 with a gap therebetween. Since it is formed integrally with the Teflon ring 3 forming the exhaust port 5,
It is made of Teflon of the same material as the Teflon ring 3.

That is, the shaft sealing device of the present embodiment is intended for a shaft sealing device of a turbo-type compressor that handles highly toxic special gas such as chlorine gas, and thus is disposed on the process side and is used as a process gas. The exposed process-side labyrinth 7 is preferably made of a Teflon material having a property strong against chlorine contained in the process gas. However, the material is not limited to the Teflon material, and any material having high durability against chlorine can be used. For example, it is a matter of course that it can be used instead of the Teflon material.

In this embodiment configured as described above, during normal operation, the supply pressure of the purge gas supplied from the supply port 4 through the supply port 12 is slightly higher than that of the exhaust port 5. This is a system that completely blocks the process gas from leaking to the atmosphere.

If an abnormal situation occurs at this stage and the pressure of the process gas becomes high, the dynamic pressure of the process gas at the exhaust port 5 is not reduced. At a position 5, the blow-through prevention fin 10 provided on the sleeve 2 attached to the rotating shaft 1 and the process-side labyrinth 7 attached to the seal housing 6 block the area of the process-side labyrinth 7 and the intermediate labyrinth 8, The phenomenon that the process gas leaked from the process side labyrinth 7 blows into the atmosphere is prevented from occurring.

That is, in the present embodiment, the structure in which the blow-through prevention fins 10 are arranged at the position of the exhaust port 5 eliminates the need to increase the number of stages of the process-side labyrinth 7, and therefore, the length of the overhang of the rotary shaft 1 is reduced. It is not necessary to lengthen the length, and it is possible to prevent the process gas from flowing into the atmosphere while maintaining the stability of the conventional shaft.

In this structure, the purge gas supplied from the air supply port 4 does not need to be particularly increased, and the purge gas can be purged at the same pressure as the conventional supply pressure. Can also be avoided.

Further, according to the present embodiment, the intermediate labyrinth 8 and the atmosphere-side labyrinth 9 are formed of a metal labyrinth such as stainless steel provided on the outer surface of the sleeve 2 integrally therewith. There is little possibility of damaging the labyrinth fin tip when assembling into the shaft sealing device, and a more reliable assembling operation can be performed.

Further, since the intermediate labyrinth 8 and the atmosphere-side labyrinth 9 are made of metal such as stainless steel, it is possible to overcome the difficulties in processing accuracy that would be difficult with Teflon materials, and to achieve more reliable processing. Accuracy can be realized.

Although the present invention has been described with reference to the illustrated embodiments, the present invention is not limited to such embodiments.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0031]

As described above, according to the first aspect of the present invention, the air supply port for supplying the purge gas and the exhaust port for returning to the process side are provided to the Teflon ring disposed on the outer periphery of the sleeve fitted on the rotating shaft. Side and the process side are separated in the axial direction, the atmosphere side labyrinth in the shaft seal part on the atmosphere side from the supply port, the intermediate labyrinth in the shaft seal part between the supply port and the exhaust port, and the process side from the exhaust port. In the shaft sealing device in which the process-side labyrinth is disposed in the shaft-sealing portion, the exhaust port protrudes radially outward from the sleeve disposed on the shaft side, and the process gas flows between the process-side labyrinth and the intermediate labyrinth. Since a blow-through prevention fin that blocks the flow of air is provided to constitute a shaft sealing device of a turbo-type compressor, an exhaust port and an air supply provided in the process side and the atmosphere side are axially separated from each other. In the exhaust port, at the exhaust port, the blow-through preventing fins protruding outward in the radial direction from the sleeve disposed on the shaft side allow the process side labyrinth even if the pressure on the process side becomes higher than the pressure of the purge gas. Between the intermediate labyrinth and the intermediate labyrinth to prevent the occurrence of blow-through, without enlarging the shaft seal, and without the need for excessive supply of seal gas. It is possible to obtain a shaft sealing device for a turbo type compressor.

According to a second aspect of the present invention, in addition to the first aspect, an atmosphere-side labyrinth provided in a shaft seal portion on the atmosphere side with respect to the air supply port, and between the air supply port and the exhaust port. The intermediate labyrinth provided in the shaft sealing portion is a metal labyrinth provided on the outer surface of the sleeve, and constitutes the shaft sealing device of the turbo type compressor. And an intermediate labyrinth provided between the supply port and the exhaust port, and a process side labyrinth provided on the process side from the exhaust port.
The atmosphere-side labyrinth and the intermediate labyrinth made of a metal labyrinth prevent the tip of the labyrinth from being damaged at the time of assembling, improve the processing accuracy of the labyrinth fin, and prevent the occurrence of the blow-through phenomenon. Thus, a more preferable shaft sealing device for a turbo compressor can be obtained.

[Brief description of the drawings]

FIG. 1 is a structural view showing a shaft sealing device of a turbo type compressor according to an embodiment of the present invention.

FIG. 2 is a structural view showing a shaft sealing device of a conventional turbo type compressor.

[Explanation of symbols]

 Reference Signs List 1 rotating shaft 2 sleeve 3 Teflon ring 4 air supply port 5 exhaust port 6 seal housing 7 process side labyrinth 8 intermediate labyrinth 9 atmosphere side labyrinth 10 blow-through prevention fin 11 exhaust port 12 air supply port

Claims (2)

[Claims] 1. A Teflon ring disposed on the outer periphery of a sleeve fitted on a rotating shaft is provided with an air supply port for supplying a purge gas and an exhaust port for returning to a process side, separated from each other in an axial direction to an atmosphere side and a process side. The atmosphere-side labyrinth is arranged in the shaft-sealed part on the atmosphere side from the air supply port, the intermediate labyrinth is arranged in the shaft-sealed part between the air supply port and the exhaust port, and the process-side labyrinth is arranged in the shaft-sealed part on the process side from the exhaust port. In the shaft sealing device, the exhaust port is provided with blow-through prevention fins that protrude radially outward from a sleeve disposed on the shaft side and block a flow of process gas between a process-side labyrinth and an intermediate labyrinth. Features a turbo-sealed compressor shaft seal device. 2. An atmosphere-side labyrinth provided in a shaft sealing portion on the atmosphere side from the air supply port, and an intermediate labyrinth provided in a shaft sealing portion between the air supply port and the exhaust port are provided on an outer surface of the sleeve. The shaft sealing device for a turbo type compressor according to claim 1, wherein the shaft sealing device is constituted by a metal labyrinth provided.