JPH0772591B2 - Leak alarm of mechanical seal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for detecting gas leaking from a mechanical seal.

[0002]

2. Description of the Related Art Conventionally, mechanical seals are used to seal fluid shafts. The mechanical seal is designed to be sealed by the presence of the working fluid that is to be sealed on the sliding surfaces of the rotary ring and the fixed ring, so the working fluid should not leak from between the rotary ring and the fixed ring to the outside. Is inevitable. Since the amount of leakage of the fluid is small, it is difficult to detect even if the leakage fluid is a liquid, and if it is a gas, it is diffused and cannot be detected. Therefore, a leak gas vent hole is provided on the outside of the fixed ring of the mechanical seal, and a pipe is led from this hole to the leak gas detector.

FIG. 4 shows a conventional example. Leakage gas discharge hole 2 from mechanical seal 10 provided in pump 1 to pipe 3
Therefore, it is guided to the leak gas detector 4. The leak gas detector 4 is connected to the pipe 3 with a detection pipe 6 whose lower end is submerged from the liquid open surface LO in the detection liquid L stored in a transparent container-shaped tank 5. The tank 5 is a closed tank and has a leaked gas discharge pipe 7 for communicating the atmosphere or a recovery tank with the upper space of the tank 5 to discharge the leaked gas to the upper part. In order to adjust the liquid level of the liquid L, a discharge valve 8 is provided at the bottom of the tank 5 and a supply valve 9 is provided at the top. As the liquid L, a type of liquid that does not explode by chemically reacting with the leaked gas is used.

In the above description, when the fluid handled by the pump 1 is a liquid whose high pressure is maintained in the pump chamber and which is a gas at room temperature and near atmospheric pressure, the stationary ring and the rotary ring for sealing the mechanical seal 10 are used. It is gas that leaks out of the sliding surface of. The liquid to be handled is accelerated and increased in pressure by the pump 1, but the pressure at that temperature is above the critical pressure. Although there is a shaft sealing device (not shown) before and after the mechanical seal 10, when the mechanical seal 10 leaks, it is a gas due to decompression and temperature rise. The substance handled by such a pump 1 is ethylene (boiling point BP-1
03 ° C, melting point M. P. Propane (BP-42.07 ° C, MP-187.69), which is a saturated hydrocarbon contained in petroleum and natural gas and is the main component of LPG.
C.), ammonia (BP-33.4.degree. C., MP-)
77.7 ° C), Freon 22 (BP-40.8 ° C,
M. P. -160 ° C) and the like.

The gas leaked from the mechanical seal 10 advances through the pipe 3 and the detection pipe 6. The pressure of this gas is the detection tube 6
When the submerged liquid length of the liquid L, that is, the pressure corresponding to the head H of the liquid L or more, the gas is discharged into the liquid L to form bubbles 20 and rise in the liquid L to rise from the liquid-open surface LO of the liquid L to the upper part of the tank 5. The gas leaks into the space and is discharged from the leak gas discharge pipe 7.

According to the leak gas detector 4 of the mechanical seal 10 as described above, the leak gas from the mechanical seal 10 can be detected by visually observing the bubbles 20.

[0007]

The mechanical seal starts to leak due to damage and wear of the sliding surface due to long-term use. Then, when the pressure of the leaked gas exceeds the pressure corresponding to the liquid column of the height of the submerged liquid in the detection tube described above, it can be detected by generation of bubbles only. Since this is a visual check, in order for this leak detector to be effective, it is necessary to check it periodically, for example, once a day or once a week. However, in this case, the leaked gas is continuously discharged from the occurrence of the gas leakage until the next time the inside of the tank 5 is observed. If the leaked gas is explosive, no oversight is allowed.

An object of the present invention is to solve the above-mentioned drawbacks of the conventional example and to provide an alarm device of a mechanical seal capable of issuing an alarm at the same time when gas leakage from the mechanical seal starts and the pressure exceeds a certain pressure.

[0009]

According to a first aspect of the present invention, a communication passage for guiding a leak gas from a mechanical seal to a diaphragm chamber and a communication passage communicating with the diaphragm chamber, a lower end of which is submerged in a liquid from an opening surface. A leak alarm for a mechanical seal, comprising a pressurizing tube, a diaphragm, a switch that operates by deformation of the diaphragm, and an alarm means that operates by the switch.

A second invention of the present invention is the leak alarm device according to the first invention, characterized in that the pressurizing pipe has a tank for storing the liquid to be immersed therein, and the tank is transparent.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a vertical sectional view of an embodiment of the present invention. The leak alarm, which is generally designated by reference numeral 11, includes an alarm 12 and a back pressure generator 13. Since the alarm 12 is provided on the upper end of the vertically long case 14 having a cylindrical shape, the screw 14a is screwed into the male screw 16a of the lower mounting portion of the chamber member 16 of the detection head 15 to form the chamber member 16 and the case
The packing 17 between them is pressed to make the case 14 airtight. Cover 18 of detection head 15 and chamber member 1
A diaphragm 19 having its periphery sandwiched and fixed by these members is stretched between 6 and a diaphragm chamber 21 is provided between the diaphragm 19 and the chamber member 16.
A communication pipe 22 is fixed to the chamber member 16,
The lower end of the communication pipe 22 exists near the bottom of the case 14. A micro switch 23 is housed and fixed in the cover 18 of the detection head 15. The actuator of the micro switch 23 faces the dog 24 fixed to the diaphragm 19, and when the dog 24 moves up, the micro switch 2
3 is adapted to be operated by pushing an actuator. The microswitch 23 is provided with a normally-open contact 23NO, a normally-closed contact 23NC and a neutral terminal 23C, each of which is led out as a lead wire to become an A, B, C terminal. A buzzer 25 is interposed between the normally open contact 23NO and the terminal A, and a pilot lamp 26 is interposed between the normally closed contact 23NC and the terminal B. An exhaust port 14b is provided at the bottom of the case 14, and an exhaust valve 28 is attached to an exhaust pipe 27 fixed to the exhaust port 14b.
Is fixed and the leaked gas in the case 14 is discharged.

A leak gas inlet 14c is provided in the case 14, and the inlet 14c and the mechanical seal 1 of the pump 1 are provided.
The leakage gas discharge hole 2 of the cover casing 1C of the pump 1 is connected by the pipe 3 so as to communicate with the space 29 on the outlet side of 0. Further, the case 14 is provided with a leak gas discharge hole 14d.

The structure of the back pressure generator 13 is the same as that of the conventional leak gas detector 4. That is, the sealed tank 5 stores a liquid L, such as water, which does not explode due to a chemical reaction with leak gas. The detection tube 6 whose lower end is submerged from the liquid open surface LO of the liquid L has its upper end fixed to the lid 5a of the tank 5,
The leak gas outlet 14d of the case 14 of the leak alarm 11 and the upper end of the detection pipe 6 are connected by a pipe 31. On the lid 5a of the tank 5, a leaked gas discharge pipe 7 that connects the atmosphere and the upper space of the tank 5 is attached. A discharge valve 8 for adjusting the liquid level of the liquid L is attached to the bottom of the tank 5, and the liquid L is provided above the tank 5.
A supply valve 9 for raising the liquid level of is attached.

The pump 1 has a suction port 1A-1 and a discharge port 1A-.
An impeller 32 is housed in a casing body 1A provided with 2. The pump casing is integrally fixed by connecting the casing body 1A, the shaft sealing casing 1B, the cover casing 1C, and the bearing casing 1D in this order. Bearing 3 that also functions as a liner ring and is fitted in the shaft-sealed casing 1B
The pump shaft 35 is rotatably supported by 3 and the bearing 34 fitted in the bearing casing 1D. Pump shaft 35
The impeller 32 is fixed to one end of the motor, and the motor shaft 37a of the motor 37 is connected to the other end via a shaft coupling 36. The electric motor 37 is fixed to the bearing casing 1D. In order to prevent the pressurized liquid in the casing body 1A from flowing into the mechanical seal chamber 38, or to reduce the pressure applied to the mechanical seal chamber 38, before or after the bearing 33 also serving as the liner ring. A shaft sealing means (not shown) is provided. The mechanical seal 10 is fitted into the cover casing 1C via an O-ring 39, and is fixed to the shaft sealing casing 1B and the cover casing 1C. The fixed ring 41 is fixed to the sliding face 41a of the fixed ring 41. And the pump shaft 3 via the O-ring 42
5, a rotary ring 43 fitted axially movably, and a compression coil spring 45 compressed between the rotary ring 43 and a spring seat 44 fitted to the pump shaft 35. The spring seat 44 is provided with a cylindrical annular portion 44a, and a halved stop ring 46 is fitted into the annular portion 44a. The stop ring 46 is fitted in the circumferential groove 35 a of the pump shaft 35. A gland packing 47 is provided in the bearing casing 1D between the back space 29 of the mechanical seal and the bearing 34.

Since the diaphragm chamber 21 communicates with the case 14 through the communication pipe 22, if the pressure of the leaking gas in the case 14 is P, the diaphragm 19 is pushed up by this pressure P, and the dog 24 operates the microswitch 23. It is like this. Further, the detection tube 6 for the liquid L in the tank 5
The pressure corresponding to the water head h from the lower end to the open liquid level LO is P1
Then, P1> P.

The operation of the above configuration will be described. When the electric motor 37 is rotated, the electric motor shaft 37a is rotated and the shaft coupling 36
The pump shaft 35 is rotated via. As a result, the impeller 32 rotates, sucks the working fluid from the suction port 1A-1, accelerates and pressurizes it, and discharges it from the discharge port 1A-2. The working fluid having a pressure applied to the back portion of the impeller 32 is prevented from flowing into the mechanical seal chamber 38 by a shaft sealing means (not shown).
When the working fluid is a liquid having a high permeability and a high pressure, the mechanical seal chamber 38 is filled with the same liquid as the working fluid, and is generally filled with oil. The shaft sealing device measures the pressure reduction in the mechanical seal chamber 38. A small amount of the liquid is vaporized and leaks into the back space 29 of the mechanical seal 10 from between the sliding surfaces 41a and 43a of the mechanical seal.

Since the temperature of the space 29 is higher than that of the working fluid and the pressure thereof is also low, the slightly leaking working fluid in the liquid phase is vaporized to increase its volume, and the leaked gas discharge hole 2 and the pipe 3 are connected to each other. As described above, the gas is sent into the case 14 from the leak gas inlet 14 c of the case 14. The leaked gas that has entered the case 14 transmits the pressure to the diaphragm chamber 21 through the communication pipe 22. Then, the diaphragm 19 is pushed up. Further, the liquid in the detection pipe 6 is pressurized through the detection pipe 6 through the leakage gas discharge hole 14d of the case 14 through the pipe 31, and the liquid surface is pushed down. Here, h is a water head applied to the open surface LO of the liquid L and the lower end of the detection pipe 6, and this pressure P1 is set to be higher than the pressure P of the leaked gas to be detected.
For example, when h = 80 mm, the pressure P1 is 0.00077k.
It becomes g / cm ² .

When the gas pressure leaking from the mechanical seal 10 reaches the upper limit pressure, the diaphragm 19 moves to the upper limit position and pushes up the dog 24 to push up the actuator of the micro switch 23. Normally open contact 23N when the actuator of micro switch 23 is not pressed
O is open, and the normally closed contact 23NC is closed. When the actuator is pushed up, the normally closed contact 2 is opened as shown in the figure.
The 3NC is opened, the pilot lamp 26 is turned off, the normally open contact 23NO is closed, and the alarm buzzer 25 sounds.

As a result, it is possible to detect the occurrence of gas leakage in the mechanical seal 10. With this leak gas alarm, there is no need to monitor daily gas leaks,
If the leak can be detected reliably and the cause of the leak from the mechanical seal is due to the reduction of the oil filled in the mechanical seal, refill the oil filled with the oil, or if the sliding surface of the mechanical seal is damaged, Either wrapping the sliding surface or replacing either the fixed ring or the rotating ring, or both.

In the present invention, since the back pressure generator 13 is provided,
When the pressure of the leaked gas exceeds P1, the leaked gas is detected by the detection tube 6
Through the liquid L to rise into bubbles 20 and rise to the tank 5
Since the gas leaks out into the upper space and leaks from the leaked gas discharge pipe 7 to the atmosphere, no abnormal increase in pressure of the leaked gas occurs, the diaphragm is not damaged, and no abnormal pressure is applied to the gland packing of the pump.

Further, in the present embodiment, the working fluid handled by the pump is a gas or a liquid, and normally comes out as a gas into the back space 29 of the mechanical seal, but in the seaside area, a liquid or a gas-liquid mixture flows into the back space 29. You can also detect cases such as those that appear in. That is, in that case, when it leaks to the space 29 as a liquid or as a gas-liquid mixture, the leaking liquid therein enters the case 14 through the leak gas discharge port 2 and the pipe 3 by gravity and collects at the bottom of the case 14. . When the leaked liquid L rises over the lower end of the communication pipe 22 as shown in FIG. 2, even if the leaked gas pressure is low, the head H of the liquid in the communication pipe 22 generated by the leaked liquid LL causes the microswitch 23 to move. The buzzer 25 sounds when the head of water corresponding to the pressure P to be operated is reached. Since the leakage of the mechanical seal can be known also by this, in the present embodiment, the leakage fluid can be applied regardless of gas or liquid.

[Embodiment 2] In the leak alarm of Embodiment 1, since the back pressure generator is separate from the alarm, extra piping is required. In the second embodiment, the leak alarm is integrated with the alarm and the back pressure generator. The same parts as those in the previous embodiment are designated by the same reference numerals, and different parts will be described. The leak gas inlet is not provided in the case 14, and the back space 29 of the mechanical seal and the diaphragm chamber 21 are connected by the pipe 3. There is.

The leak gas discharge hole 14d of the case 14 is open to the atmosphere or leads to a recovery tank. A discharge valve 8 for reducing the liquid L in the case 14 from the bottom of the case 14 is provided, and a supply valve 9 for supplying the liquid L into the case 14 is provided at the top of the case 14. As the liquid L, a liquid that does not explode by chemically reacting with the leaked gas, such as water, is selected as in the previous embodiment. The vertical size between the liquid open surface LO of the liquid L stored in the case 14 and the lower end of the communication pipe 22 is h as in the previous embodiment. In this case, it is appropriate to make the case 14 transparent so that the height of the open liquid level LO can be visually observed, or to provide a liquid level detector.

When there is leaked gas from the mechanical seal 10, the gas leaked to the back space 29 of the mechanical seal transmits pressure to the leaked gas discharge hole 2, the pipe 3 and the diaphragm chamber 21, and goes upward from the diaphragm chamber 21. Then, the diaphragm 19 is pushed up and the liquid L in the communication pipe 22 is pushed downward. As a result, the buzzer 25 sounds and it is possible to know the leakage of the mechanical seal. When the pressure of this leaking gas is higher than the water head h, the liquid level of the liquid L in the communication pipe 22 is pushed down, and the leaking gas goes out into the liquid L in the case 14 and rises as bubbles to open the liquid. Since it leaks from the surface LO to the upper space of the case 14 and is discharged into the atmosphere through the leak gas discharge port 7, it is possible to prevent the pressure of the leak gas from rising abnormally as in the previous embodiment.

[0026]

According to the present invention, the gas leaked from the mechanical seal is introduced into the diaphragm chamber, the switch is operated by the displacement of the diaphragm to obtain a signal, and the liquid in the tank is placed between the diaphragm chamber and a constant atmospheric pressure part such as the atmosphere. A back pressure generating means is provided so that the gas pressure of the diaphragm chamber is applied to one of the liquid-opening surfaces and the space on the other liquid-opening surface is kept at a constant pressure such as atmospheric pressure. It was possible to provide a leak gas alarm with a mechanical seal that operates depending on the pressure of leak gas.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment of the present invention.

FIG. 2 is a vertical sectional view for explaining an additional action of the first embodiment.

FIG. 3 is a vertical sectional view of a second embodiment.

FIG. 4 is a vertical sectional view of a conventional example.

[Explanation of symbols]

 1 Pump 3 Piping 12 Alarm 13 Back Pressure Generator 15 Detection Head 19 Diaphragm 23 Micro Switch 25 Buzzer

Claims (2)

[Claims] 1. A communication passage for guiding a leaked gas from a mechanical seal to a diaphragm chamber, a pressurizing pipe communicating with the diaphragm chamber and having a lower end submerged in a liquid from a liquid-opening surface, the diaphragm and actuated by deformation of the diaphragm. A leak alarm for a mechanical seal, comprising a switch for operating and a warning means actuated by the switch. 2. The leak alarm device according to claim 1, wherein the pressurizing pipe has a tank for storing the liquid to be submerged, and the tank is transparent.