JPH08303607A - Mechanical seal - Google Patents

Abstract

PURPOSE: To provide a mechanical seal which can be easily built into a pump, by forming an extinctive fluid injecting chamber to the inside of a mounting flange, and sealing this extinctive fluid injecting chamber by a shaft circumferential seal, in the mechanical seal provided with the extinctive fluid injecting chamber into which extinctive fluid is injected. CONSTITUTION: In a mechanical seal, when sealed fluid is leaked from seal means 1, a pilot nozzle 4 is melted by the heat of the fluid and compressed air is let from a passing hole 42 so that supplying pressure is lowered, thus these states are detected by a pressure switch, and steam is injected from a pipeline 5 into a steam injecting chamber C. Hereby, leaked fluid can be prevented from being ignited. In this case, the steam injecting chamber C is formed to the inside of a mounting flange 2, and sealed by a shaft circumferential seal 3. Hereby, the sealed properties of the steam injecting chamber C can be excellently secured, and the injected steam can be assuredly prevented from being splashed to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical seal. More specifically, the present invention mainly relates to a mechanical seal used for sealing a pump or the like for transporting a high-ignitability and high-temperature fluid.

[0002]

2. Description of the Related Art Conventionally, in a petroleum refining plant, a chemical plant, or the like that handles a fluid having a high ignitability and a high temperature, a mechanical seal having a digesting function has been used for a shaft sealing portion of a pump for transporting a fluid ( For example, Jikho Sho 57
-15440 publication). FIG. 2 is a sectional view showing an example of this type of mechanical seal. This mechanical seal includes a stationary seal ring 91 fixed to the housing H,
A rotary seal ring 92 attached to the rotary shaft S so as to be integrally rotatable.
The sealing means 90 for sealing the fluid by bringing the respective sealed ends into close contact with each other is provided.

The stationary seal ring 91 has a mounting flange 9
A second mounting flange 95 is provided behind the mounting flange 93 with a hollow portion 94 provided on the inner peripheral side thereof. Further, on the inner periphery of the second mounting flange 95, a shaft peripheral seal (segment ring) 99 is integrally rotated with the rotating shaft S as an emergency seal in the event that fluid leaks from the sealing means 90. It is possible. Further, the side surface of the second mounting flange 95 is
It is covered with a split cover 97 in a state where a predetermined gap is provided, and the gap is configured as a steam chamber 96 for injecting steam as a digestive fluid.

A pilot nozzle 98 for detecting the leakage of fluid from the sealing means 90 is introduced into the hollow portion 94 on the inner peripheral side of the mounting flange 93. The pilot nozzle 98 has a cylindrical shape with a closed tip, and a large number of through holes are formed in the body of the pilot nozzle 98. Each through hole is closed with a low melting point metal such as solder. Compressed air (or gas) is constantly supplied to the inside of the pilot nozzle 98, and the sealing means 9 is used.
When the sealing fluid leaks from 0, it is detected that the low melting point metal is melted by the heat and the compressed air flows out from each through hole, and the pressure of the compressed air is reduced. It can be detected. And
The steam chamber 96 is connected to a steam supply means (not shown), and when leak of the sealed fluid is detected, steam is injected into the steam chamber 96 to prevent the leaked fluid from catching fire or to catch fire. The leaked fluid can be digested.

[0005]

In the mechanical seal having the above-described structure, the fire extinguishing function can be easily added to the existing mechanical seal, but a radial gap is formed between the rotary shaft S and the cover 97. Since the cover 97 has a split structure and an axial gap is formed in the joint portion of the cover 97, the steam injected into the steam chamber 96 is scattered to the outside through the radial gap and the axial gap. To do. Therefore, there is a problem that it is not possible to sufficiently secure the extinguishing performance of the ignited leaked fluid.

A bearing for supporting the rotary shaft S is provided behind the cover 97, but high temperature steam scattered from the cover 97 and fluid leaked from the sealing means 90 are The grease that has been filled in the bearing leaks out when it hits the bearing.
There is also a problem that it adversely affects the rotation performance and life. Further, since the mechanical seal has a long total length in the axial direction, the space for assembling is relatively narrow, and there is a problem that it is difficult to assemble it into a pump or the like. This invention has been made in view of the above problems, and is excellent in extinguishing performance of the ignited sealed fluid,
It is an object of the present invention to provide a mechanical seal that has few adverse effects on bearings and is easy to install.

[0007]

SUMMARY OF THE INVENTION To solve the above problems, a mechanical seal of the present invention comprises a stationary seal ring fixed to a housing via a mounting flange, and a rotary seal mounted to a rotary shaft so as to be integrally rotatable. Sealing means for sealing the fluid by closely contacting the respective sealed ends of the ring, an emergency circumferential seal for sealing the fluid leaked from the sealing means, and leakage of the fluid from the sealing means In a mechanical seal provided with a leak detecting means for detecting a leak, and a leak detecting means detecting a leak of fluid from the sealing means, a digestive fluid injection chamber into which a digestive fluid is injected is provided inside the mounting flange. A digestive fluid injection chamber is formed, and the digestive fluid injection chamber is sealed by the axial seal.

[0008]

According to the mechanical seal having the above construction, the digestion fluid injection chamber is formed inside the mounting flange of the stationary seal ring, and the digestion fluid injection chamber is sealed by the axial seal. Therefore, it is possible to prevent the fire extinguishing fluid injected into the fire extinguishing fluid injection chamber from scattering to the outside or the fluid leaking from the sealing means from leaking to the outside of the mechanical seal. Further, since the digestion fluid injection chamber is provided inside the mounting flange,
The overall length of the mechanical seal in the axial direction can be shortened.

[0009]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of the mechanical seal of the present invention. This mechanical seal is used for a shaft seal portion of a pump that transports a fluid having high ignitability and high temperature, and can rotate integrally with a stationary seal ring 1a fixed to a housing H of the pump and a rotary shaft S. A sealing means 1 for bringing the respective sealing ends 1c, 1d of the rotary sealing ring 1b attached to each other into close contact with each other to seal the fluid; and a mounting flange 2 for mounting the stationary sealing ring 1a on the housing H, The emergency shaft seal 3 for sealing the fluid leaking from the sealing means 1 and the pilot nozzle 4 as a leak detecting means for detecting the leakage of the fluid from the sealing means 1 constitute a main part. There is.

A sleeve S1 is integrally rotatably fitted on the rotary shaft S, and a flange portion S2 of the sleeve S1 is fitted.
On the other hand, the rotary seal ring 1b is fixed. The mounting flange 2 includes a flange main body 21 fixed to the housing H, and a baffle 22 extending from the flange main body 21 to the sealing means 1 side. The flange body 21 is a combination of a first flange piece 21a and a second flange piece 21b. Both flange pieces 21a, 21b are fixed to the housing H in a state of being integrated by a bolt B1. ing. The baffle 22 has its base end fixed to the inner peripheral portion of the flange piece 21a by a bolt B2, and its tip end extends to the sealing means 1 side with a gap provided between the baffle 22 and the sleeve S1. The stationary seal ring 1a is fitted to the tip of the stationary seal ring 1a in a state in which the stationary seal ring 1a is allowed to slide in the axial direction. A bellows 1e for pressing the stationary seal ring 1a toward the rotary seal ring 1b is provided on the outer periphery of the baffle 22.

A hollow portion is provided on the inner circumference of the flange body 21, and the hollow portion is configured as a steam injection chamber (digestion fluid injection chamber) C for injecting steam which is a digestion fluid. Has been done. This steam injection chamber C
In the figure, the inner peripheral clearance on the left side is sealed by the shaft peripheral seal 3. In addition, the flange piece 21b of the flange body 21 is provided with an injection port 23 for injecting steam into the steam injection chamber C and a drain port 24 for discharging the steam injected into the steam injection chamber C. The steam supply pipe 5 is connected to the inlet 23, and the steam discharge pipe 6 is connected to the drain port 24.

The shaft seal 3 is integrally rotatably fitted to the outer circumference of the sleeve S1. The shaft peripheral seal 3 is made of carbon, and a garter spring 31 is wound around the outer periphery thereof. This shaft circumference seal 3
In the figure, two are provided, each of which is arranged on the inner circumference of the flange piece 21b. Further, each axial seal 3 is slidably sandwiched between an annular flange portion 21c provided on the inner circumference of the flange piece 21b and a plate 21d attached to the side surface of the flange piece 21b.

The pilot nozzle 4 is introduced into a radial hole 24 formed in the flange piece 21a of the flange body 21. The radial hole 24 communicates with the steam injection chamber C, and the tip of the pilot nozzle 4 is
It faces the steam injection chamber C. This pilot nozzle 4 is a well-known one in which a large number of through holes 42 are formed in the body portion of the tubular body 41 and each through hole 42 is closed by a low melting point metal such as solder. Compressed air is constantly supplied to the pilot nozzle 4 through a pipe 7.

In the mechanical seal, if a sealing fluid leaks from the sealing means 1, the low melting point metal of the pilot nozzle 4 is melted by the heat of the leaking fluid and compressed air flows out from the through hole 42. However, since the supply pressure of the compressed air drops, this is detected by a pressure switch (not shown), and steam is injected into the steam injection chamber C through the pipe 5. Therefore, it is possible to prevent the leakage fluid from igniting, and it is possible to extinguish the leakage fluid if it has already ignited. Further, in the above mechanical seal, the steam injection chamber C is formed inside the mounting flange 2 and the steam injection chamber C is sealed by the axial seal 3, so that the steam injection chamber C is well sealed. can do. Therefore, as a result of effectively preventing the steam injected into the steam injection chamber C from scattering outside, it is possible to exhibit excellent digestion performance, and
It is possible to prevent the conventional inconvenience that the steam scatters on the bearing adjacent to the mechanical seal and adversely affects the rotational performance and life of the bearing.

Moreover, the mechanical seal has a structure in which the steam injection chamber C is provided inside the mounting flange 2, so that the overall length in the axial direction can be shortened. Therefore, it becomes easy to install the mechanical seal in the pump. Furthermore, the fluid leaking from the sealing means 1 can be prevented from leaking to the outside by the shaft seal 3, so that the leaking fluid does not have a bad influence on the rotational performance and the life of the bearing. In addition to steam, various liquids or gases having a digestive function can be used as the digestive fluid.

[0016]

As described above, according to the mechanical seal of the present invention, the digestive fluid injection chamber is formed inside the mounting flange for the stationary seal ring, and the digestive fluid injection chamber is sealed by the axial seal. Since it is stopped, it is possible to effectively prevent the digestive fluid injected into the digestive fluid injection chamber from scattering outside the mechanical seal. Therefore, it is possible to improve the extinguishing performance of the ignited leaked fluid, and it is possible to prevent the fire extinguishing fluid from adversely affecting the rotational performance and the life of the bearing adjacent to the mechanical seal. Further, it is possible to prevent the fluid leaking from the sealing means from scattering to the outside of the mechanical seal by the axial seal, so that the leaking fluid is prevented from adversely affecting the rotation performance and the life of the bearing. be able to. Moreover, since the mechanical seal can shorten the overall length in the axial direction,
It has a unique effect that it can be easily incorporated into a pump or the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a mechanical seal of the present invention.

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 Sealing Means 1a Stationary Sealing Ring 1b Rotating Sealing Ring 1c Sealing End 1d Sealing End 2 Mounting Flange 3 Axial Seal 4 Pilot Nozzle (Leakage Detection Means) C Steam Injection Chamber (Digestion Fluid Injection Chamber) H Housing S Rotation Shaft

Claims (1)

[Claims] 1. A seal for sealing a fluid by closely contacting respective sealed ends of a stationary seal ring fixed to a housing via a mounting flange and a rotary seal ring integrally rotatably mounted on a rotary shaft. Means, an emergency shaft seal for sealing the fluid leaking from the sealing means, a leak detecting means for detecting that the fluid has leaked from the sealing means, and a fluid leaking from the sealing means by the leak detecting means. When it is detected, in the mechanical seal including the digestion fluid injection chamber into which the digestion fluid is injected, the digestion fluid injection chamber is formed inside the mounting flange, and the digestion fluid injection chamber is A mechanical seal that is sealed by a shaft seal.