JPS6146288Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a load adjustment device for a mechanical seal.

As is well known, for conventional mechanical seals, the sealing load is fixedly determined by the design specifications of the mechanical seal and the conditions of the rotating equipment such as the pump to which it is attached. It is virtually impossible to predict this and adjust the load force acting on the sealed end face from the outside.

By the way, for example, due to design errors during the initial design or changes in the operating conditions of rotating equipment, there is a risk that an excessive load force, that is, an overload, will be applied to the sealed end face. In this case, the lubrication effect on the sealed end face is not performed properly, and as a result, the amount of wear on the sealed end face increases dramatically, significantly shortening the life of the mechanical seal, and in extreme cases, the sealed end face seizes and becomes damaged. This results in various abnormal situations such as the amount of leakage from the sealed end face exceeding the allowable range and the sealing function being unable to be achieved.

However, with conventional mechanical seals, it is extremely difficult to detect the occurrence of an overload before an abnormal situation such as the one described above occurs, and therefore it is impossible to prevent such an abnormal situation from occurring. Even if it is possible, and even if the occurrence of an overload can be detected in advance, the only way to prevent the occurrence of the abnormal situation is to stop the operation of the rotating equipment itself. Stopping the operation of rotating equipment often leads to the stoppage of the entire plant, which is extremely inconvenient.

This invention was made in view of the above points,
Provides a new mechanical seal load adjustment device that can predict changes in the sealing state by detecting temperature changes on the sealed end face, and adjust the load force acting on the sealed end face from the outside based on this prediction, thereby preventing seizure. The purpose is to prevent the occurrence of abnormal situations such as this, and maintain a good sealing function over a long period of time.

Next, an example thereof will be explained with reference to the drawings. This embodiment relates to an example in which the present invention is applied to a mechanical seal attached to a pump.

In the figure, 1 is a seal housing, 2 is a rotary shaft extending from the pump chamber and penetrating through the seal housing 1, and 3 and 4 are rotating seal rings and stationary seals disposed in the seal housing 1, respectively. It is a ring. The rotating sealing ring 3 is fitted and fixed to the rotating shaft 2, and the stationary sealing ring 4 is supported by a sleeve 5 that is fitted onto the rotating shaft 2 so as to be movable in the axial direction. The rotary ring 3 is also biased by a compression coil spring 7 interposed between the rotary ring 3 and a seal flange 6 attached to the rotary ring 3. Note that 8 is a nut screwed onto the rotating shaft 2.

A main sealed chamber 10 is formed in the seal housing 1 so as to face the sealed end surfaces 9 of the rotating sealing ring 3 and the stationary sealing ring 4. This main sealed chamber 10 is communicated with a sealed fluid side 12, which is the suction side of the pump chamber, via a communication passage 11 formed between the seal housing 1 and the rotating shaft 2. Further, in a portion of the seal housing 1 that substantially opposes the sealed end surface 9, a high pressure source of the pump, such as a discharge port 14, is provided.
An inflow hole 13 is formed which is connected to the main chamber 10 through a communication pipe 15 and opens into the main sealed chamber 10.
The fluid supplied into the main sealed chamber 10 from the discharge port 14 through the communication pipe 15 and the inflow hole 13 is configured to flow out to the sealed fluid side 12, which is the low pressure side.
During this time, the sealed end surface 9 is designed to be cooled.

Also, a sub-sealed chamber 16, which is independent of the main sealed chamber 10, is provided facing the back side of the sealing ring on the side that applies a load force to the sealing end face 9 of the two sealing rings 3, 4, that is, the stationary sealing ring 4. is formed. That is, by sealing between the stationary seal ring 4, the seal housing 1, and the seal flange 6 using the O-ring packings 17 and 18, the sub-seal chamber 16 is constructed so that the seal housing 1, the stationary seal ring 4, and the seal are sealed. It is formed as a sealed space surrounded by a flange 6, and is connected to a fluid supply mechanism 20, which will be described later.
Fluid at a predetermined pressure is supplied by the pump.

Therefore, the fluid pressure acting in both sealed chambers 10 and 16 causes a predetermined load force to be applied to the sealed end face 9, thereby sealing the sealed fluid side 12 from the atmospheric side 19. being done. In this sealed state, the fluid in the main sealed chamber 10 lubricates the sealed end surface 9.

Furthermore, a fluid supply mechanism 20 that supplies fluid into the sub-sealed chamber 16 and is capable of increasing or decreasing the fluid pressure; a temperature detector 21 that detects the temperature of the sealed end surface 9; Since a control mechanism 22 is provided to control the fluid supply mechanism 20 in order to adjust the difference between the fluid pressures in the sealed chambers 10 and 16 to a set differential pressure in accordance with the detected temperature value, first the fluid is The supply mechanism 20 will be explained.

That is, a supply pump 23 separate from the pump equipped with the mechanical seal, which is operated to keep the discharge pressure constant at all times, is provided, and this supply pump 2
The suction pipe 24 of No. 3 is led to a suitable water source 25, and its discharge pipe 26 is branched, and one branch pipe, a supply pipe 26a, is formed in the seal housing 1 and opens into the sub-sealed chamber 16. Inflow hole 27
The reflux pipe 26b, which is the other branch pipe, is connected to the water source 25 and is connected to the reflux pipe 26b.
A pressure regulating valve 28 is provided at b.

Therefore, according to this fluid supply mechanism 20,
Fluid is supplied from the discharge pipe 26 to the sub-sealed chamber 16 via the supply pipe 26a and the inflow hole 27, and excess fluid is returned to the water source 25 from the reflux pipe 26b, so the supply pump 23 is operated at a constant discharge pressure. In conjunction with this, the fluid pressure within the sub-sealed chamber 16 is maintained at a constant pressure. By operating the pressure regulating valve 28 to adjust the pressure of the fluid flowing into the reflux pipe 26b, the fluid pressure within the sub-sealed chamber 16 can be increased or decreased.

The temperature detector 21 also includes a thermocouple 29 mounted on a portion of the stationary sealing ring 4 located very close to the sealing end face 9.
The thermocouple 29 is connected to a temperature indicator 30 so that the temperature of the sealed end surface 9 can be detected.

Further, the control mechanism 22 includes a converter 31, a differential pressure transmitter 32, and a controller 33.

The converter 31 turns on the controller 33 when the temperature of the sealed end face 9, that is, the temperature value indicated by the temperature indicator 30, is above a set value, and turns off the controller 33 when it is below the set value. Thus, the controller 33 is controlled to be turned on and off according to the temperature value detected by the temperature detector 21. In addition,
The set value is determined in consideration of various conditions such as the load condition of the mechanical seal, and is set to the maximum temperature before an abnormal situation occurs such as the sealing end face 9 seizing, for example. You can leave it there.

Further, the differential pressure transmitter 32 is interposed in a connecting pipe 34 that connects the communication hole 15 and the supply pipe 26a, and is connected to a connecting pipe 34 that connects the communication hole 15 and the supply pipe 26a. Detects the difference in fluid pressure between
The set value data is input to the controller 33.

Then, when the converter 31 turns ON, the controller 33 controls the differential pressure value successively detected by the differential pressure transmitter 32 to approach the set value, that is, the difference between the two sealed chambers 10 and 16. The fluid pressure in the sub-sealed chamber 16 is automatically adjusted by adjusting and controlling the pressure regulating valve 28 so that the pressure becomes a set differential pressure. Note that this set differential pressure is calculated from the total axial pressure that the stationary seal ring 4 receives from the fluid in the sub-sealed chamber 16 to the total axial pressure that the stationary seal ring 4 receives from the fluid in the main sealed chamber 10 (that the seal end surface 9 receives). The total pressure (including the total pressure) is subtracted, that is, the differential pressure is set at which the load force acting on the sealing end face 9 exhibits the best sealing function.

Next, the operation of the load adjustment device according to the present invention will be explained with reference to the above embodiment.

When the load force acting on the sealed end face 9 is within an allowable range and the lubrication state of the sealed end face 9 is stable, the temperature of the sealed end face 9 is stable even if there is some fluctuation.

Therefore, in such a state, the temperature value detected by the temperature detector 21 becomes lower than the set value, and
The control mechanism 22, that is, the controller 33 is not turned on, and the fluid pressure in the sub-sealed chamber 16 is maintained constant.

However, for example, due to a change in the operating conditions of the pump, the fluid pressure in the main sealed chamber 10 decreases significantly, causing overload to act on the sealed end surface 9, or the cooling conditions of the sealed end surface 9 worsening. For example, if the supply of fluid from the inflow hole 13 to the main sealed chamber 10 is drastically reduced or stopped, the temperature of the sealed end surface 9 will rise abnormally, and the temperature detector The temperature value detected in step 21 becomes equal to or higher than the set value.

In this way, when the temperature of the sealed end surface 9 becomes equal to or higher than the set temperature, the controller 33 is turned on by the converter 31, and the pressure regulating valve 2 is turned on by the controller 33.
8 adjustment control is started.

This adjustment control is performed until the differential pressure value input by the differential pressure transmitter 32 reaches the set value, that is, until the differential pressure between the sealed chambers 10 and 16 is adjusted to the set differential pressure.

In this way, when the fluid pressure in the sub-sealed chamber 16 is adjusted so that the differential pressure between the two sealed chambers 10 and 16 becomes the set differential pressure, an appropriate load force will be applied to the sealed end surface 9. The sealed end face 9 is well lubricated, and abnormal situations such as seizure are prevented from occurring.
Good sealing function is maintained.

When such a good sealing state is restored, the temperature of the sealed end face 9 begins to drop, and when it falls below the set temperature, the converter 31 turns off the controller 33.
Once activated, the adjustment control of the pressure regulating valve 28 is stopped, and the pressure within the sub-sealed chamber 16 is kept constant.

It should be noted that the load adjustment device according to the present invention is of course not limited to the above embodiment. For example, in the above embodiment, when the load force acting on the sealing end face 9 becomes excessive, the sealing Focusing on the point where the temperature of the end face 9 rises, this temperature rise is detected and the load force is reduced and adjusted, but on the other hand, the load force becomes too small and the amount of leakage from the sealed end face 9 becomes insufficient for lubrication. It is also possible to increase the load force even if the load force exceeds the limit.

In other words, when a leak occurs as described above,
Since the temperature of the sealed end face 9 is significantly lower than that under proper lubrication, the temperature value detected by the temperature sensor 21 is within the set range, that is, the load force and lubrication state of the sealed end face 9 are appropriate. When the temperature of the sealed end face 9 is within the temperature range at a certain time, the controller 33 is not turned on, but when the temperature value is above or below the set range, the converter 31 turns on the controller 33. All you have to do is set it to ON.

By doing this, even if the load force on the sealed end face 9 becomes either too high or too low, the temperature of the sealed end face 9 can be detected to increase or decrease the load force to the appropriate load force. Thus, the sealing function can be maintained well.

Further, in the fluid supply mechanism 20, the discharge pressure is adjusted by increasing or decreasing the rotation speed of the supply pump 23 without providing the pressure regulating valve 28,
The fluid pressure within the sub-sealed chamber 16 may be increased or decreased by this. In this case, the control mechanism 22 controls the rotation speed of the supply pump 32.

Further, the control mechanism 22 may not be fully automatic as in the embodiment described above, but may be partially or entirely manual. For example, temperature sensor 21
In addition to replacing the temperature indicator 30 with a simple thermometer and eliminating the converter 31, the temperature of the sealed end face 9 is visually detected by the thermometer, and the controller 33 is artificially turned on and off. You may also do so. Furthermore, the controller 33 is also eliminated, and a differential pressure detector is installed in the connecting pipe 34 instead of the differential pressure transmitter 32, and the pressure is adjusted while visually detecting the differential pressure detector and the thermometer. The valve 28 may also be manually operated.

The components of the fluid supply mechanism 20, temperature detector 21, and control mechanism 22 described above are all conventionally known.

Furthermore, the load adjustment device according to the present invention can be applied not only to mechanical seals attached to pumps as in the above embodiments, but also to mechanical seals attached to all kinds of rotating equipment. The present invention can also be applied to the mechanical seal of the type in which one sealing ring 3 is rotated and the other sealing ring 4 is stationary in the above embodiment. Further, the sub-sealed chamber 16 has an O
Instead of sealing with the ring packings 17 and 18, it is also possible to use a metal bellows or the like.

In any case, as is clear from the above explanation, according to the mechanical seal load adjustment device of the present invention, abnormalities in the sealing state can be predicted by detecting the temperature of the sealing end face, and the fluid inside the sub-sealing chamber Since the pressure can be adjusted and the load force acting on the sealed end face can be adjusted from the outside, it is possible to prevent the occurrence of the abnormal situation mentioned at the beginning, greatly extending the life of the mechanical seal and ensuring long-term use. A good sealing function can be maintained throughout.

Moreover, pressure fluctuations in the main sealed chamber, that is, on the sealed fluid side, can be tolerated over a wide range, making it possible to greatly extend the usage limits of the mechanical seal.

[Brief explanation of the drawing]

The figure is a schematic vertical sectional view showing an embodiment of a mechanical seal load adjustment device according to the present invention. 3... Rotating sealed ring, 4... Stationary sealed tube, 9... Sealed end face, 10... Main sealed chamber, 16... Sub-sealed chamber, 20... Fluid supply mechanism, 21... Temperature detector, 22... Control mechanism.

Claims (1)

[Scope of utility model registration request] A main sealed chamber facing the sealed end faces of the stationary sealing ring and the rotating sealing ring and connected to the sealed fluid side, and facing the back side of one of the sealing rings that applies a load force to the sealed end face. A sub-sealed chamber is formed independent of the main sealed chamber, and a fluid supply mechanism is provided for supplying fluid into the sub-sealed chamber and changing the fluid pressure, thereby controlling the temperature of the sealed end surface. A control mechanism is provided that includes a temperature detector for detecting the temperature, and controls the fluid supply mechanism in accordance with the temperature value detected by the temperature detector to adjust the difference between the fluid pressures in the two sealed chambers to a set differential pressure. A mechanical seal load adjustment device characterized by the following: