JPH11271167A - Method and apparatus for diagnosis of abnormality in leak limitation-type seal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus, for the diagnosis of an abnormality in a leak limitation-type seal device, in which the abnormality in the seal device can be detected at an early stage so as to be capable of being diagnosed with good accuracy. SOLUTION: The signal of the pressure of seal water, that of the temperature of the seal water and that of the shaft displacement of a main shaft 15 are fetched from pressure gages 20, 22, thermometers 21, 23 and a displacement meter 26. A change in a seal flow rate is analyzed by an analyzer 31 by using the signals. The deviation between an analyzed flow rate obtained by this analysis and a measured seal flow rate is found. By using the obtained deviation, the correlation between itself and an abnormality operating parameter is analyzed. An analyzed result is displayed on a display screen 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for diagnosing abnormalities in a seal device of a leakage-restriction type applied to seal apparatuses for various pumps. The present invention relates to a method and apparatus for detecting and diagnosing an abnormality of a sealing device in a pump, a cooling water pump, a recirculation pump, and the like.

[0002]

2. Description of the Related Art In general, an abnormality prediction system and an abnormality diagnosis system for sealing devices of various pumps are performed by the following method. (A) Using a statistical method to analyze past failure cases,
The correlation between the change in the flow rate and the failure of the seal is examined based on the operating conditions, time, and the like, and the cause is estimated by temporally predicting the failure and probabilistic analysis of the cause of the abnormality. (B) Attach a sensor to the seal ring, measure stress and temperature, and grasp the progress of seal failure or deterioration.

[0003]

The method of the above (a) is as follows.
In fact, in the case of a pump device, which is an important device in a power plant, there are few failure cases and statistical processing cannot be performed. In the above method (b), since the seal is an important element and is at a pressure boundary, the mounting of the sensor may cause a new failure, and is not an optimal means. That is the fact.

On the other hand, a leak limiting type seal called a static pressure seal is used for a pump having a high differential pressure and a high speed rotation, and the flow rate of the seal varies depending on the seal differential pressure, the seal fluid temperature, or the rotation speed. Since it changes in a complicated manner in relation to the axial displacement amount due to, for example, it is difficult to find a sign of abnormality or the like at an early stage only by monitoring the seal flow rate. Generally, an upper limit or a lower limit of the seal flow rate is set, and it is a general monitoring method to determine that the seal is abnormal when the seal flow rate exceeds the upper limit or the lower limit.

In a simple seal, as described above,
In addition to the seal flow rate, there are cases where special sensors such as thermometers and vibrometers are attached and these signals are used for abnormality diagnosis.However, special sensors are installed for pumps and other important equipment such as power plants. However, the reliability of the sensor itself becomes a problem, and the reliability of the sensor itself becomes a problem.

[0006] In operation, the pressure is applied to the sealing device by utilizing the pressure of the fluid to be sealed, which floats to form a film, or the relative sliding speed of the sealing ring and the mating mating ring due to the rotation of the shaft with the rotation of the shaft. In a leak limiting type seal, such as a dynamic seal that dynamically forms a film, due to the seal differential pressure, fluid temperature, or these changes, due to the elastic deformation or thermal deformation of the shaft or casing, It is known that the seal flow rate changes due to the small relative change that occurs. At first glance, the seemingly complicated change in the seal flow rate has a deep relationship with the elastic deformation of the seal ring or the friction of the seal components due to the axial movement.

For example, when the seal differential pressure is increased, the flow rate increases in proportion to the seal differential pressure. However, the seal ring and the mating ring undergo elastic deformation, and the characteristic diagram of the seal differential pressure and the flow rate shown in FIG. As shown, the seal flow rate is not proportional to the seal differential pressure and may have an arcuate characteristic. Also,
When the seal differential pressure is reduced, the seal flow rate becomes hysteretic. This is considered to be due to the fact that the shaft slightly moved due to the seal differential pressure and friction between members constituting the secondary seal and the seal device. Because the amount of thermal deformation of the shaft and casing is slightly different for both the seal fluid temperature and the shaft and seal fluid temperature,
Generally, the seal flow rate has hysteresis.

[0008] As described above, the seal flow rate changes depending on the seal differential pressure, the seal fluid temperature, the axial displacement, and the like. As described above, it was found that the seal abnormality can be grasped at an early stage by separating the change as the seal characteristic and the change as the seal abnormality sign from the seal flow that changes at first glance. Accordingly, it is an object of the present invention to provide an abnormality diagnosis method and an abnormality diagnosis device for a leakage-limiting type seal device that enable early detection of an abnormality in the seal device and accurate diagnosis.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a hydrostatic seal or a sealing ring and a mating ring for forming a film by using, for example, a fluid pressure. It is applied to an abnormality diagnosis method of a leakage limiting type sealing device having a dynamic pressure seal that dynamically forms a film using relative slip,
The feature is that a relational expression between the deterioration factor and the seal flow rate is obtained based on the deterioration data obtained by the test or the actual operation of the seal device, and the closest factor is determined by comparison with the measured seal flow rate. Is identified as the cause.

Further, the invention according to claim 2 is applied to an abnormality diagnosis device for a leak-restriction type sealing device similar to that described above, and seals using a signal of pressure, temperature or shaft displacement of a main shaft. Means for analyzing a change in the flow rate, deviation deriving means for obtaining a deviation between the analysis flow rate obtained by the analysis means and the actual measured seal flow rate, and a correlation between any operating parameter using the deviation obtained here. It is characterized by having correlation analysis means for analyzing and display means for displaying the analysis result.

The present invention will be specifically described. In the aforementioned static pressure seal or dynamic pressure seal, the seal differential pressure, the seal water temperature, the shaft change, etc. are related to each other depending on the viscosity of the fluid, the friction between the seal components, or the elastic deformation, the seal shape due to thermal deformation. The film thickness is determined and the seal flow rate is determined.

Although the seal flow rate appears to vary intricately due to a plurality of factors due to hysteresis and the like, reproducible results can be obtained by determining the test conditions and testing. From this, the relationship between the factors and the results was analyzed, tests were performed as necessary, and the phenomena were analyzed. As a result, it was found that the flow rate of the seal changed according to one rule.

By clarifying such a change in the seal flow rate and its factors and formulating a quantitative relationship, a so-called computer simulation program for analyzing the seal flow rate could be created. Regarding the relationship between the friction coefficient and the surface roughness of the friction sliding surface, the accuracy of the simulation is ensured by using a method such as obtaining data experimentally and obtaining an empirical formula representing the characteristics from the data. Each factor is taken up one by one, and the relationship with the failure is clarified by accelerated tests etc. under strict experimental conditions, and this is incorporated into a computer simulation program.
Some factors are simple, or two or more overlap, resulting in a change in seal flow rate.

In making the abnormality diagnosis device, the most severe deterioration / failure is set to the maximum value based on the seals without deterioration / failure and the results of the tests so far for each factor.
In the meantime, input can be made in several stages. Then, the seal water temperature and the seal flow rate (hereinafter referred to as Tq characteristics) or the seal water pressure and the seal water flow rate (hereinafter referred to as pq characteristics) are obtained by using a simulation technique. It is assumed that the actual operation data is input for changes in the seal water temperature and the seal differential pressure.

Now, for example, as an example, when a sign of an increase in the measured seal flow rate is observed, the relationship with the seal water temperature or the seal water pressure is examined retrospectively. Then, the seal water temperature or the seal water pressure is input to a program for simulating the above-described deterioration / failure of this pattern, and the seal differential pressure is examined. At this time, the degree of deterioration is simply changed for each factor, and Tq
By selecting the characteristic and the pq characteristic that are closest to the actual measurement, the factor and the degree of deterioration can be estimated.

In an actual important device, failure or deterioration of two or more factors occurs at the same time and rarely becomes obvious, and it is usually important to identify a single cause. Therefore, in the present invention, the signal of the seal differential pressure, the seal water temperature, or the relative movement amount of the shaft is taken into the computer from the actually operating pump, and the seal is not abnormal by the computer simulation program pre-installed. The analytical value of the seal flow rate at that time is obtained.

The deviation between this value and the seal flow rate during operation,
That is, assuming that the analysis value is q ₀ and the measured seal flow rate is q, the deviation Δq = q−q ₀ can be expressed. When this deviation is large, it is determined that the seal is abnormal or has signs thereof. q ₀ is the corrected flow rate, such as seal-specific characteristics and temperature, it is possible to detect signs of accurate abnormality.

After it is determined that the deviation Δq is large, the relationship between the measured seal flow rate and the seal temperature or the seal differential pressure is examined. When the data is small, the seal water temperature or the seal differential pressure is intentionally changed and data is obtained.

The same seal water temperature or seal differential pressure as in the operation is input to a computer simulation program and compared with the pq characteristic or the Tq characteristic. At this time, the degree of deterioration for each factor is input, and the one closest to the pattern is selected. A plurality of factors may be selected, but these are factors that may be the cause, and the operating conditions and the like can be changed, and the cause can be identified by a similar trial.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative positions, and the like of the structural components described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified. It is only an example.

FIG. 1 shows a pump device provided with an abnormality diagnosis device for a leakage-limiting type seal device in a pump device according to an embodiment of the present invention. Reference numeral 10 denotes a pump main body, and a suction pipe 12 is provided at a lower portion of a casing thereof, and a discharge pipe 13 is provided at a side portion thereof. An upper part of the pump body 10 is a seal casing 14, and a seal device described later is provided in the seal casing 14. The main shaft 15 rotating in the seal casing 14 is connected to an electric motor 17 via a coupling 16.
The coupling 16 is provided with a displacement gauge 26, where the axial displacement K is measured.

The seal casing 14 is provided with a seal water supply pipe 18 at a lower part and a seal water return pipe 19 at an upper part. The seal water supplied from the seal water supply pipe 18 passes through the seal casing 14, and seal water (cooling water) from a secondary seal (No. 2 seal) described later flows. Seal water supply pipe 18
Is provided with a pressure gauge 20 and a seal water thermometer 21, where a seal water pressure P ₁ and a seal water temperature T ₁ are measured. The seal water return pipe 19 is provided with a pressure gauge 22, a seal water return thermometer 23, and a return flow meter 24, where the pressure P ₂ , the seal water return temperature T ₂ , and the return flow rate Q are respectively set. It is being measured.

These measurement signals are taken into the computer 30 via the signal processing device 27. The computer 30 incorporates a seal flow rate simulation program for analyzing the flow rate of the seal using the signals of the axial displacement K, the temperatures T ₁ , T ₂ , and the pressures P ₁ , P _2. 31. And this analysis device 3
A display unit 32a for obtaining a deviation ΔQ (= Q−Q ₀ ) between the value Q ₀ of the result of the simulation according to 1 and the actual seal flow rate Q, and analyzing and displaying a correlation with an arbitrary operation parameter.
Is provided.

FIG. 2 is a detailed view of a part of the analyzer 31 of FIG. 1 and shows a process of calculating the simulation value Q ₀ . Based sealing pressure P ₁ was incorporated into the computer 30, the seal water temperature T _1, the cooling water temperature T _2, the temperature T _3, and the shaft displacement data K ₁₁ the relative displacement ΔX of the secondary seal (to be described later) to a predetermined program The analysis is performed by the arithmetic unit 31a. Next, a has been ΔX analyzed by the computing unit 31a, the frictional force data K _21, it analyzes the arithmetic unit 31b based on the frictional force F of Sekanrishiru a predetermined program.

Furthermore, the frictional force of the secondary seal is analyzed by the arithmetic unit 31b F, the seal water temperature T _1, deformation ΔS of the cooling water temperature T _2, the sealing member from the temperature T ₃ and the seal ring deformation data K _31, Is analyzed by the calculation unit 31c based on a predetermined program. Further, the operation unit 3
1b and 31c, the frictional force F, the deformation ΔS of the seal member, the seal water temperature T ₁ , the cooling water temperature T ₂ , and the air temperature T
_3, the value Q ₀ of the simulation from the seal characteristics K ₄₁
Is analyzed by the calculation unit 31d based on a predetermined program.

FIG. 3 shows an example of the configuration of the shaft seal portion of the coolant pump. Seal casing 1 to which the seal water supply pipe 18 and the seal water return pipe 19 are attached.
4 has a support 36 to which an insert 35 is fastened.
Is fitted. A seal ring 37 is slidably fitted in the insert 35 in the axial direction. On the other hand, an adapter 38 is attached to the main shaft 15, and a runner ring 40 and a shaft sleeve 41 are attached to the adapter 38. A shaft sleeve 44 is attached to the upper portion of the shaft sleeve 41 via a mating ring 43, and a secondary seal (NO.2 seal) 42 is attached to the mating ring 43.

The runner ring 40 rotates together with the main shaft 15 via the adapter 38. This seal is tapered so that the film h on the outer peripheral side of the seal ring 37 becomes thicker.
a has been processed so that a stable film h
Is a static pressure seal that holds the pressure.

Reference numeral 45 denotes a flange attached to the upper portion of the seal casing 14 via screws 46, and reference numeral 48 denotes a flange attached to the lower portion of the support 36 via screws 49. The fluid to be sealed is supplied from the seal water supply pipe 18 to the space 52 on the outer periphery of the main shaft 15 and flows through the film h to the downstream side 53. The fluid on the downstream side 53 cools the secondary seal 42 and returns to the seal water return pipe 19.
And collected in a drain tank (not shown).

A pump impeller (not shown) is provided below the main shaft 15 so as to rotate in a high-pressure fluid. The upper part of the main shaft 15 is connected to the electric motor 17.

FIG. 4 shows the results of simulation of a normal seal (solid line) and an abnormal seal (chain line) in which the friction of the secondary seal 42 has increased. That is, although the operation (seal water temperature) is within the upper and lower limits, the state where the insert 35 (see FIG. 3) is roughened and the friction of the secondary seal 42 is increased. The figure is a graph of a flow rate characteristic in which the X axis is the seal water temperature and the Y axis is the seal flow rate (the same applies hereinafter). From this result, it can be seen that in the case of an abnormal seal, the width of the hysteresis increases.

FIG. 5 shows the results of a simulation of a normal seal and an abnormal seal in which the taper amount of the seal is increased. From this result, in the case of an abnormal seal,
It can be seen that the width of the hysteresis is not so large, but the flow rate is large.

FIG. 6 is a graph showing simulation results of a normal seal and an abnormal seal in which the taper amount of the seal is reduced. From this result, it can be seen that in the case of an abnormal seal, the hysteresis width is not so large, but the flow rate is small.

FIG. 7 is a graph showing simulation results of a normal seal and an abnormal seal in which friction on the back surface of the face plate is increased. From this result, it can be seen that in the case of an abnormal seal, the hysteresis increases.

FIG. 8 is a graph showing simulation results of a normal seal and an abnormal seal in which the O-ring on the back surface of the face plate has changed. From this result, it can be seen that when the seal water differential pressure is small (lower line), it is not different from the normal seal, but when the seal water differential pressure (upper line) increases, the flow rate increases.

As described above, by confirming the characteristics of the seal components by experiments and formulating them into a seal flow simulation program, it is clear that characteristic flow characteristics are exhibited depending on the cause of the seal failure. Was.

FIG. 9 shows an example of actual measured flow rate characteristics with the seal water pressure on the X axis and the seal flow rate on the Y axis. FIG.
Is an example of a diagnosis screen (deterioration data editing screen) of the abnormality diagnosis device, in which the vertical indicates the cause of the abnormality and the horizontal indicates the degree of deterioration indicating the degree of the abnormality. Then, the maximum possible degree of deterioration is expressed as 5.0, and the normal seal is expressed as 0. In principle, the cause can be identified by sequentially simulating the selected points in this figure and selecting the one closest to the pattern in FIG. Depending on the factors,
Although two or more causes may remain, it is possible to follow the flow rate by changing the history of the operation and the flow rate up to now or the operation parameters, and to clarify the cause.

In order to identify the cause, on the diagnostic screen shown in FIG.
Assuming that the degree of deterioration is the maximum of 5.0, a plurality of n as shown in FIG.
Simulate the flow rate for the sample data of
Find the average of the analysis. Then, using the Newton-Raphson method or the like, the degree of deterioration X _i equal to the flow rate of the actually measured value is calculated. This is represented by the following “Equation 1”.

[0038]

(Equation 1)

The degree of deterioration X _i is obtained from the above “Equation 1”. At this time, the sum of squared deviations SS _i and standard dispersion μ measured values and analysis values obtained from the following formula "number 2" and "number 3".

[0040]

(Equation 2)

[0041]

(Equation 3)

From these results, X _i <0, X _i > 5.
When it is 0, the tendency is different, but since it exceeds the conceivable degree of deterioration, it is canceled. The evaluation is "x". When μ is small, for example, 0.15 or less, the possibility of the cause is large, and the evaluation is “評 価”. Also, 0.15 <μ <
The evaluation at 0.4 is “O”.

FIG. 11 shows the result of abnormal diagnosis of the data shown in FIG.
In this figure, Χ ₁ , SS, μ, and evaluation for each factor are displayed at the top. The measured value is indicated by a solid line, and the dotted line indicates an analysis value obtained by inputting the cause of the abnormality. As is clear from this figure, the measured values and the analysis values are almost the same. In the above embodiment, when the standard variance μ does not decrease, the factor of the smallest standard variance is determined by inputting the value of X _i when obtaining the reference value q ₀ and performing the same abnormality diagnosis as described above. By finding the second cause, the standard variance can be reduced.

[0044]

As described above in detail, according to the present invention, in a leak limiting type seal device provided with a static pressure seal or a dynamic pressure seal, etc., the influence of the deterioration factor on the seal flow rate is confirmed by a test. However, it is possible to automatically identify the cause of deterioration from simulations by formulating these as mathematical formulas, and it is difficult to discover abnormalities only by monitoring the seal flow rate. This makes it possible to diagnose the abnormality of the device with high accuracy, and is particularly effective for the abnormality diagnosis of the seal device of the pump device of the power plant where the number of failure cases is small and statistical processing is difficult.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an abnormality diagnosis device for a leakage-restriction-type sealing device according to the present invention.

FIG. 2 is a block diagram illustrating details of an arithmetic processing portion according to the embodiment;

FIG. 3 is a sectional view of a shaft seal portion of a coolant pump to which the present invention is applied.

FIG. 4 is a graph showing characteristics of a seal water temperature and a seal flow rate when the friction of the secondary seal is large.

FIG. 5 is a graph showing characteristics of seal water temperature and seal flow rate when the seal taper is large.

FIG. 6 is a graph showing the characteristics of seal water temperature and seal flow rate when the taper of the seal is small.

FIG. 7 is a graph showing the characteristics of the seal water temperature and the seal flow rate when the back friction of the face plate is large.

FIG. 8 is a graph showing characteristics of a seal water temperature and a seal flow rate when the O-ring is deteriorated.

FIG. 9 is a graph showing an example of a measured flow rate characteristic of an abnormal seal flow rate.

FIG. 10 is an example of a display screen diagram of the abnormality diagnosis device.

FIG. 11 is a graph showing an abnormality diagnosis result.

FIG. 12 is a graph showing a relationship between a seal differential pressure and a seal flow rate.

[Explanation of symbols]

 12 Main shaft 18 Seal water supply pipe 19 Seal water return pipe 20, 22 Pressure gauge 21, 23 Thermometer 26 Displacement gauge 30 Computer 31 Computing device 31a, 31b, 31c, 31d Computing unit 32 Display unit 37 Seal ring 42 Secondary seal 43 Tingling

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[Procedure amendment]

[Submission date] May 26, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

The seal casing 14 is provided with a seal water supply pipe 18 at a lower part and a seal water return pipe 19 at an upper part. The seal water supplied from the seal water supply pipe 18 passes through the inside of the seal casing 14 so that the seal water (cooling water) flows. The seal water supply pipe 18 is provided with a pressure gauge 20 and a seal water thermometer 21, where the seal water pressure P ₁ and the seal water temperature T ₁ are measured. A pressure gauge 2 is provided on the seal water return pipe 19.
2, a seal water return thermometer 23 and a return flow meter 24 are provided, where a pressure P ₂ , a seal water return temperature T
₂ and the return flow rate Q are respectively measured.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0023

[Correction method] Change

[Correction contents]

These measurement signals are taken into the computer 30 via the signal processing device 27. The computer 30 incorporates a seal flow rate simulation program for analyzing the flow rate of the seal using the signals of the axial displacement K, the temperature T ₁ T ₂ , and the pressures P ₁ and P _2. have. And this analysis device 3
A device 32 is provided for obtaining a deviation ΔQ (= Q−Q ₀ ) between a value Q _{0 obtained as} a result of the simulation by No. 1 and the actual seal flow rate Q, and analyzing and displaying a correlation with an arbitrary operation parameter.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

FIG. 3 shows an example of the configuration of the shaft seal portion of the coolant pump. Seal casing 1 to which the seal water supply pipe 18 and the seal water return pipe 19 are attached.
4 has a support 36 to which an insert 35 is fastened.
Is fitted. A seal ring 37 is slidably fitted in the insert 35 in the axial direction. On the other hand, an adapter 38 is attached to the main shaft 15, and a runner ring 40 and a shaft sleeve 41 are attached to the adapter 38. A shaft sleeve 44 is attached to the upper portion of the shaft sleeve 41 via a mating ring 43, and a NO. Two seals are installed.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

[0038]

(Equation 1)

[Procedure amendment 5]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

Claims (2)

[Claims] 1. A method for diagnosing an abnormality of a leakage limiting type seal device, comprising: obtaining a relational expression between a deterioration factor and a seal flow rate based on deterioration data obtained by a test or an actual operation of the seal device; A method of diagnosing an abnormality in a leakage limiting type sealing device, wherein a factor closest to the comparison is determined and the cause is identified. 2. An abnormality diagnosis device for a leak limiting type seal device, comprising: means for analyzing a change in seal flow rate using a signal of pressure, temperature or shaft displacement of a main shaft of a seal water, and an analysis obtained by the analysis means. There are deviation deriving means for calculating a deviation between the flow rate and the measured seal flow rate, correlation analyzing means for analyzing a correlation with an arbitrary operation parameter using the obtained deviation, and display means for displaying the analysis result. An abnormality diagnosis device for a leakage-restriction-type sealing device, characterized in that: