JPH0420104B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting wear over time or abnormal wear of each component of a mechanical seal.

[Conventional technology]

A mechanical seal performs a shaft sealing function by axially opposing a rotating sliding ring that is airtightly supported by the shaft and a stationary sliding ring that is airtightly supported by a housing. If the sealing sliding surfaces of both sliding rings are abnormally worn due to operation under high load conditions, insufficient lubrication, or surface roughness due to the intrusion of foreign matter, a large amount of leakage may occur. Furthermore, wear of the gasket, etc. that maintains airtightness between the rotating sliding ring and the shaft or between the stationary sliding ring and the housing also has a significant effect on sealing performance.

However, in the past, there was no way to predict leakage accidents due to the progress of wear as described above, and therefore, in order to prevent leakage accidents from occurring, it was necessary to periodically disassemble the equipment and inspect the mechanical seals. .

[Problem to be solved by the invention]

However, despite the above-mentioned maintenance and inspection, there are many cases in which it is not known that the mechanical seal is abnormal until a large amount of leakage has actually occurred.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to predict abnormalities in mechanical seals before a large amount of leakage occurs, and to enable appropriate measures to be taken.

[Means to solve the problem]

The method for detecting the wear state of a mechanical seal according to the present invention involves sampling a certain amount of circulating fluid discharged through a stuffing box equipped with a mechanical seal at a predetermined time, and then adding It is characterized by selecting and capturing the contained particles and analyzing the size, amount, form, etc. of the selected and captured particles.

[Effect]

The circulating fluid that lubricates and cools the sliding surfaces of the mechanical seal and is discharged from the stuffing box contains a small amount of fine particles, and these fine particles include abrasion powder generated from the mechanical seal. The present invention attempts to detect whether or not an abnormality has occurred in a mechanical seal by analyzing particulates in this circulating fluid.

The fine particles contained in the circulating fluid are abrasion particles generated from mechanical seals, such as sliding rings made of metal, carbon, ceramic, PTFE, etc., and polymer materials (rubber, etc.) that are in pressure contact with the sliding rings.
This can be broadly classified into three types: abrasion powder from gaskets, abrasion powder and rust from pipelines and equipment that form the circulation path for circulating fluid, and foreign matter that has entered from outside. In addition, the particle size of the wear particles generated from mechanical seals is larger when the wear is caused by cutting due to the intrusion of foreign objects, lack of lubrication, high load, etc. than when the wear occurs during normal operation. The shape differs depending on the type of wear.

Therefore, by sampling the circulating fluid discharged from the stuffing box and analyzing the size, amount, form, etc. of the particles contained in the sampled fluid, it is possible to determine the wear location and type of wear in the mechanical seal. It is possible to estimate the degree of wear, progress, and factors causing wear.

〔Example〕

Below, we will analyze particulates in the circulating fluid from a stuffing box equipped with a mechanical seal.
An embodiment of the present invention using a ferrograph will be described based on the drawings.

In Fig. 1, reference numeral 1 indicates the entire seal unit of the stirrer, and the lower end 3a is connected to the stirring blade in the reaction vessel (not shown) on the inner periphery of the housing 2, and the upper end 3b is connected to the gear on the motor side (not shown). The shaft 3 is inserted through the shaft 3. In a stuffing box 4 formed between the inner peripheral surface of the housing 2 and the outer peripheral surface of the shaft 3, two mechanical seals 5a and 5b are provided vertically side by side. The mechanical seals 5a and 5b are connected to a fixed side sliding ring 6 fixed to the housing 2 and a shaft 3, respectively.
The rotating sliding ring 7 rotates with the fixed sliding ring 6 and is brought into close contact with the fixed sliding ring 6 by the spring 8, and the rotating sliding ring 7 is interposed between the fixed sliding ring 6 and the housing 2 and between the rotating sliding ring 7 and the shaft 3. It is equipped with a sealed packing,
Both sliding rings 6 and 7 slide closely against each other to perform a shaft sealing function.

The housing 2 has a circulating fluid inlet 10 whose inner end opens near the sliding part 9a of the lower mechanical seal 5a in the stuffing box 4, and an inner end which opens near the sliding part 9a of the upper mechanical seal 5b in the stuffing box 4. A circulating fluid discharge port 11 is provided near the moving part 9b.

On the other hand, 12 is installed outside the stirrer, and the discharge port 1
7 is connected to the circulating fluid inlet 10 via piping 20, and a return port 18 is connected to the circulating fluid outlet 11 via piping 21. The stored circulating fluid is
A pump 16 driven by a motor 15 supplies the stuffing box 4 from the filter 14 through the discharge port 17, piping 20, circulating fluid inlet 10, etc., and from the stuffing box 4 to the circulating fluid outlet 1.
1. The circulating fluid discharged through the pipe 21 is recovered into the tank 13 from the return port 18 through the cooling device 19 and the like.

Reference numeral 22 denotes a circulating fluid collection pipe 23 that branches off from the middle of the pipe 21 and extends from the pipe 21, and this circulating fluid collection pipe 2.
This sampling device consists of an electromagnetic valve 24 which is installed in the middle of the pipe 3 and whose opening/closing operation is controlled by a timer 25, and a sampling cup 26 which is installed at the liquid outlet of the circulating fluid sampling pipe 23.

As already mentioned, the circulating fluid that passes through the stuffing box 4, lubricates and cools the mechanical seals 5a and 5b, and is discharged from the circulating fluid discharge port 11 includes various parts that make up the mechanical seals 5a and 5b. In addition to wear particles generated from piping 20,
Rust and wear particles generated from the 21 and various valves installed in the middle, as well as foreign matter that has entered from the outside, etc.
Contains various fine particles. A part of the circulating fluid containing the particles, which is recycled from the sampling device 22 and the circulating fluid outlet 11 to the circulating fluid pressurized supply device 12 through the piping 21, is controlled to open and close a solenoid valve 24 driven by a timer 25. Therefore, a certain amount of sampling is performed periodically.

The particles in the sample liquid (circulating liquid) collected in the sampling cup 26 are analyzed using a particle separator 27 schematically shown in FIG. That is, this separation device 27 has a thin glass plate 28 that is slightly inclined, and magnets 30, 30 that generate a magnetic flux A that crosses this glass plate 28 in a direction perpendicular to the direction of inclination. Weir 2 formed on the upper surface of glass plate 28 by flowing out from thin pipe 31
9 from the high side 28a to the bottom side 28b, and the fine particles B contained in the sample liquid are selected and captured by a magnetic field.

To explain this in more detail, among the fine particles B in the sampling liquid, particles made of magnetic material such as iron are caught by the magnetic field between the magnets 30 and oriented on the glass plate 28 in the direction of the magnetic flux A. The particles remain in a striped pattern and are fixed in descending order of the size of the particles that are most easily captured by the magnetic field (this is called a ferrograph). In addition, non-magnetic particles are captured by being caught by magnetic particles, but if ions are fixed on the surface of non-magnetic particles using an ion fixing solution, they can be captured by the magnetic field. It is possible. Next, the glass plate 28 on which the fine particles B are fixed is irradiated with light of different colors from both the upper and lower sides at the same time.
Observe the size, amount, shape, color, surface condition, etc. of fine particles B using a microscope.

As a result of the above observation, for example, when the fixed side sliding ring 6 of the mechanical seal 5a is made of carbon, a large number of carbon particles are included in the particles B captured on the glass plate 28 by the particle separator 27. If it is included, it can be determined that the fixed side sliding ring 6 of the mechanical seal 5a is severely worn. Similarly, if the fine particles B contain particles of rubber or the like, it can be said that the packing has worn out. For example, if a large number of sand grains or glassy foreign objects that seem to have entered from the outside are found in particulate B, even if the current amount of wear is small, the cutting wear caused by these foreign objects (the surface of the sliding surface It is estimated that roughness) will progress quickly. Further, as a result of experiments, it has been found that there is a close relationship between the form of fine particles (wear debris) and the factors that cause wear debris to occur, and some examples thereof are as follows.

(a) Very small round particles with a smooth surface → Wear particles generated during normal operation (b) Small particles with a round shape and smooth surface → Wear particles generated during initial run-in operation ( c) Large adhered particles with irregular shapes and scratches on the surface → wear particles generated under high load, high speed, and high temperature conditions (d) Large chip-like particles → irregularities on the surface of the mating material,
Cutting wear particles generated due to foreign matter entering from outside (e) Round particles that are oxidized black → Wear particles generated due to high temperature or lack of lubrication (f) Round particles that are oxidized red → Combination with water or air Red rust formed on powder made of iron-based materials due to contact.As mentioned above, the size, amount, and form of fine particles B contained in the circulating fluid discharged through stuffing box 4 will be analyzed. Therefore, it is possible to grasp the location where wear occurs in the mechanical seals 5a, 5b, the cause of the wear, the progress state, etc., and it is possible to take appropriate measures such as replacing parts and circulating fluid.

〔Effect of the invention〕

As is clear from the above explanation, the present invention focuses on the fact that the circulating fluid passing through the stuffing box contains wear powder generated from mechanical seals, and analyzes this wear powder quantitatively and qualitatively. By doing so, it is possible to accurately detect the wear condition of mechanical seals, eliminating the need for disassembling equipment and inspecting mechanical seals, and preventing leakage accidents from occurring. be able to take appropriate measures to achieve this goal.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG.
The figure is a schematic perspective view showing a particle analyzer. 4...stuffing box, 5a, 5b...
Mechanical seal, 6... Fixed side sliding ring, 7...
Rotating side sliding ring, 11...Circulating fluid outlet, 12...
Circulating fluid pressurization supply device, 22... Sampling device, 23... Circulating fluid collection piping, 24... Solenoid valve, 25... Timer, 26... Sampling cup, 2
7... Particulate separation device, B... Particulates.

Claims (1)

[Claims] 1. Sampling a certain amount of circulating fluid discharged through a stuffing box equipped with a mechanical seal at a predetermined time, then sorting and capturing fine particles contained in the sampled fluid,
A method for detecting the wear state of a mechanical seal, which is characterized by analyzing the size, amount, form, etc. of the selected and captured particulates.