JP2015184029A - Diagnostic method for swing check valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diagnostic method for a swing check valve which can accurately predict the occurrence of deterioration by diagnosing the detailed operation state of the swing check valve, and diagnoses the degree of deterioration of the swing check valve.SOLUTION: A diagnostic method for a swing check valve for diagnosing the operation state of the swing check valve storing a check valve unit performing arcuate motion with a valve rod as a support shaft in a valve box comprises: a position determination process which makes an ultrasonic wave incident into the valve box from an ultrasonic sensor installed in the valve box and determines the position of the check valve unit on the basis of the ultrasonic wave reflected by the check valve unit; a behavior determination process which determines the state of the behavior of the check valve unit on the basis of the change of the peak position of the ultrasonic wave measured by the ultrasonic sensor for each measurement time; and a collision determination process which detects the collision noise generated in the valve box by using an AE sensor installed in the valve box and determines the presence/absence of collision between the check valve unit and the valve box on the basis of the detected collision noise.

Description

  The present invention relates to a swing check valve diagnosis method for diagnosing the detailed operation state and deterioration state of a swing check valve.

  Conventionally, in a power plant or the like, a swing type check valve (swing check valve) is used in order to prevent an internal fluid such as gas or liquid from flowing backward in the pipe.

  FIG. 13 is a diagram schematically showing a cross-sectional structure of a general swing check valve, in which (A) is a fully open state and (B) is a fully closed state.

  As shown in FIG. 13, the swing check valve 1 includes a valve box 2, a valve rod 4 accommodated in the valve box 2, a check valve unit 3 that moves arcuately using the valve rod 4 as a support shaft, And a valve lid 10 attached to the upper opening surface of the box 2. The check valve unit 3 includes an arm 6 having a through hole 7 through which the valve rod 4 is inserted, and a valve body 8 attached to the arm 6 by a valve body bolt 9 and a valve body nut 20.

  In the check valve unit 3, when the internal fluid flows forward in the pipe, the valve body 8 is opened by the arc motion with the valve rod 4 as a support shaft until the arm 6 contacts the backstop 14, At the time of reverse flow, the valve body 8 is configured to close by performing an arcuate motion until the valve body 8 contacts the valve seat 12.

  However, in the actual swing check valve 1, the check valve unit 3 vibrates or collides with the valve box 2 such as the backstop 14 or the valve seat 12 due to a subtle difference in the flow rate of the internal fluid. If the valve rod 4 and the arm 6 continue to be used as they are, the rotating portion where the valve stem 4 and the arm 6 are in contact, the threaded portion of the valve body bolt 9 and the valve body nut 20, the check valve unit 3 and the valve Both contact portions of the box 2 may be worn and the swing check valve may be deteriorated.

  When the deterioration due to wear of the rotating part and the screwing part progresses, the check valve unit 3 may drop out and the swing check valve 1 may not function. Further, when the deterioration due to wear of the contact portion progresses, the sealing property between the valve seat 12 and the valve body 8 is impaired, and there is a possibility that internal fluid leaks. For this reason, diagnosing the operating state of the swing check valve 1 is an effective means for predicting the occurrence of deterioration.

  Conventionally, as a method of diagnosing the operating state of the swing check valve 1, a method of simply diagnosing the open state and the fully closed state by measuring the flow rate of the internal fluid has been used. It has been difficult to accurately diagnose the detailed position of the stop valve unit 3, a state where it is stably stopped, or a state where it is vibrating.

  Further, as in Patent Document 1, a method of detecting an abnormal event in which the check valve unit is not normally operated due to sticking or the like by detecting a collision sound at the time of valve opening or valve closing using an AE sensor. Has been developed. However, this method is also intended to easily determine the fully open state and the fully closed state, and is not sufficient for diagnosing the detailed position and behavior of the check valve unit.

  Further, as in Patent Document 2, a diagnostic device for diagnosing an abnormal event has been developed by observing a sudden acoustic peak in a valve that does not generate sound in normal times. In addition, it is difficult to apply this diagnostic device to a check valve in which a collision between the check valve unit and the valve box is repeated in normal operation.

JP 2010-117330 A JP-A-5-172696

  Therefore, an object of the present invention is to provide a diagnosis method for a swing check valve that can diagnose the detailed operating state of the swing check valve and accurately predict the occurrence of deterioration. Furthermore, this invention makes it a subject to provide the diagnostic method which diagnoses the grade of deterioration of a swing check valve.

The invention described in claim 1
A check method for a swing check valve for diagnosing the operating state of a swing check valve in which a check valve unit that moves arcuately with a valve stem as a support shaft is housed in a valve box,
A position determination step for determining the position of the check valve unit based on ultrasonic waves that are incident on the valve box and reflected by the check valve unit from an ultrasonic sensor installed in the valve box;
A behavior determination step for determining a state of behavior of the check valve unit based on a change in measurement time of the peak position of the ultrasonic wave measured by the ultrasonic sensor;
A collision that detects an impact sound generated in the valve box using an AE sensor installed in the valve box, and determines whether or not the check valve unit and the valve box collide based on the detected collision sound. A swing check valve diagnostic method comprising: a determination step.

The invention described in claim 2
The position determination step is based on ultrasonic waves that are incident on the valve box from an ultrasonic sensor installed above or below the check valve unit in the valve box and reflected by the check valve unit. 2. The swing check valve diagnosis according to claim 1, wherein a distance between the ultrasonic sensor and the check valve unit is measured, and a position of the check valve unit is determined based on the measured distance. Is the method.

The invention according to claim 3
In the position determination step, ultrasonic waves are incident on the valve box from an ultrasonic sensor installed on a side surface of the valve box, and based on the presence or absence of ultrasonic waves reflected by the check valve unit, the check valve unit 2. The swing check valve diagnosis method according to claim 1, wherein the position is determined.

The invention according to claim 4
The collision sound is detected using the AE sensor, and the frequency distribution of the collision sound is obtained by frequency analysis of the acoustic peak of the detected collision sound,
Deterioration for diagnosing the degree of deterioration of the check valve unit by comparing the obtained frequency distribution of the collision sound with the preset frequency distribution of the collision sound when the check valve unit is not deteriorated The swing check valve diagnosis method according to any one of claims 1 to 3, further comprising a diagnosis step.

The invention described in claim 5
A check method for a swing check valve for diagnosing a deterioration state of a swing check valve in which a check valve unit that moves arcuately using a valve stem as a support shaft is housed in a valve box,
The collision sound generated in the valve box is detected using an AE sensor installed in the valve box, and the frequency distribution of the collision sound is obtained by frequency analysis of the acoustic peak of the detected collision sound.
Deterioration for diagnosing the degree of deterioration of the check valve unit by comparing the obtained frequency distribution of the collision sound with the preset frequency distribution of the collision sound when the check valve unit is not deteriorated A diagnostic method for a swing check valve characterized by comprising a diagnostic step.

  ADVANTAGE OF THE INVENTION According to this invention, the detailed operating state of a swing check valve can be diagnosed, and the diagnostic method of the swing check valve which can predict generation | occurrence | production of deterioration correctly can be provided. Furthermore, a diagnostic method for diagnosing the degree of deterioration of the swing check valve can be provided.

It is a flowchart which shows the outline | summary of the diagnostic method of the swing check valve which concerns on this invention. It is explanatory drawing which shows the installation position of the ultrasonic sensor in 1st Embodiment. It is a graph which shows the reflective echo measured by the ultrasonic sensor. It is a graph which shows an example of the change for every measurement time of the peak position of a reflective echo. It is a graph which shows an example of transition of time until the peak position of a reflective echo is measured from incidence of an ultrasonic wave. It is a graph which shows an example of the collision sound detected by the AE sensor. It is explanatory drawing which shows the other installation position of the ultrasonic sensor in 1st Embodiment. It is explanatory drawing which shows the installation position of the ultrasonic sensor in 2nd Embodiment. It is a graph which shows an example of the acoustic peak of the collision sound measured by the AE sensor. It is a graph which shows an example of the frequency distribution of a collision sound. It is a figure which shows the result in each of the position determination process, behavior determination process, and collision determination process in an Example. It is a graph which shows the analysis result of the frequency distribution of the collision sound in an Example. It is a figure which shows typically the cross-section of a general swing check valve.

1. Outline of the Invention As described above, the swing check valve vibrates the check valve unit or collides with a valve box such as the backstop 14 or the valve seat 12 due to a subtle difference in the flow rate of the internal fluid. It may be used in a state where Therefore, the present inventor first decided to classify and diagnose the operation state of such a swing check valve into the five states shown in Table 1 below.

  Then, according to the flowchart showing the outline of the diagnosis method of the swing check valve according to the present invention shown in FIG. 1 (hereinafter also simply referred to as “diagnosis method”), the position determination process, behavior determination process, and collision determination process are performed. It is determined to which of the classifications in Table 1 the operating state of the check valve belongs.

  First, in the position determination step, an ultrasonic wave is incident on the valve box from the ultrasonic sensor, and the check valve unit is positioned close to either the backstop or the valve seat based on the ultrasonic wave reflected by the check valve unit. Determine if there is.

  As a result, the check valve unit is in a fully open state, backstop collision, or vibration state on the backstop side (S1), or is in a vibration, valve seat collision, or fully closed state on the valve seat side. It is possible to determine which is in (S2).

  Next, in the behavior determination step, it is determined whether or not the check valve unit is moving for each of S1 and S2 based on the change of the measured ultrasonic peak position for each measurement time.

  If the check valve unit is not moving, it is determined that the valve is in the fully open state (S3) in S1, and the fully closed state (S5) in S2, while if the check valve unit is moving, In S1, it is determined that there is a backstop collision or vibration state (S4), and in S2 that there is any vibration or valve seat collision state (S6).

  Next, in the collision determination step, by detecting a collision sound using an AE (Acoustic Emission) sensor, the moving check valve unit does not collide with the backstop or the valve seat for each of S4 and S6. Determine whether.

  If a collision sound is confirmed, it is determined in S4 that the vehicle is in a backstop collision state (S7), and in S6, a valve seat collision state (S9). On the other hand, if no collision sound is confirmed, S4 and S6 In any case, it is determined that the vibration state is present (S8, S10).

  As described above, the swing check valve diagnosis method according to the present invention determines the operation state of the swing check valve stepwise by combining the ultrasonic sensor and the AE sensor. The state can be diagnosed in more detail than before, and the occurrence of deterioration can be accurately predicted.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

2. First Embodiment FIG. 2 is an explanatory diagram showing an installation position of an ultrasonic sensor according to the present embodiment.

(1) Position determination process In this Embodiment, as shown in FIG. 2, the ultrasonic sensor 30a is installed in the upper surface 11 of the valve lid 10 above the non-return valve unit 3. And based on the measurement result of the reflected wave (reflection echo) of the ultrasonic wave which entered into the valve case 2 from the ultrasonic sensor 30a, the distance between the ultrasonic sensor 30a and the check valve unit 3 was measured and measured. Based on the distance, it is determined whether the check valve unit 3 is located closer to the backstop 14 or the valve seat 12. An example of the reflected echo measured at this time is shown in FIG.

  As shown in FIG. 3, the ultrasonic sensor 30 a measures the reflected echo from the valve box 2 or the valve lid 10 immediately after the ultrasonic wave is incident, and the reflected echo from the check valve unit 3 after a certain time has elapsed. Measure. At this time, the difference between the measurement time of the reflected echo from the valve box 2 or the valve lid 10 and the measurement time of the reflected echo from the check valve unit 3 is the time when the ultrasonic wave propagates inside the swing check valve 1. Yes, the distance between the ultrasonic sensor 30a and the check valve unit 3 is obtained by calculating the distance between the valve case 2 or the valve lid 10 and the check valve unit 3 based on the propagation time of this ultrasonic wave. Can do.

  Based on the distance between the ultrasonic sensor 30a and the check valve unit 3, the backstop 14 side is in a fully open state, a backstop collision, or a vibration state (S1), or the valve seat 12 side. It is determined whether it is in a state of vibration, valve seat collision, or fully closed (S2) (see FIG. 1).

(2) Behavior determination step Next, the state of the behavior of the check valve unit, that is, whether or not the check valve unit 3 is moving is determined based on the change of the peak position of the reflected echo for each measurement time. FIG. 4 is a graph illustrating an example of a change in the peak position of the reflected echo for each measurement time.

  As shown in FIG. 4A, when the check valve unit 3 is not moving, the peak position measurement time (peak measurement time) becomes substantially constant even when the reflected echo is measured repeatedly for a long time. In contrast, as shown in FIG. 4B, when the check valve unit 3 is moving, the peak measurement time changes.

  In this step, based on such a change in peak measurement time, it is determined whether the check valve unit 3 is moving, and the operating state of the swing check valve 1 is further divided. Specifically, when the check valve unit 3 is not moving, it is determined that the valve is in the fully open state (S3) in S1 and the fully closed state (S5) in S2, while the check valve unit 3 is in the fully closed state (S5). If it is moving, it is determined in S1 that it is in a backstop collision or vibration state (S4), and in S2 it is in a vibration or valve seat collision state (S6) (see FIG. 1).

  Furthermore, in the present embodiment, as shown in FIG. 5, the vibration width and period of the check valve unit 3 can be measured based on the change in the peak measurement time of the reflected echo. In other words, if the vibration width is large or the period is fast, it will be understood that the amount of wear will increase in the future, so the occurrence of deterioration can be predicted more accurately based on the measurement results of the vibration width and period. it can.

(3) Collision determination step Next, an AE sensor is installed outside the valve box 2 where a collision sound can be easily detected, the collision sound generated in the valve box 2 is detected, and the movement is performed based on the detected collision sound. It is determined whether the swing check valve is colliding with the backstop or the valve seat. An example of the collision sound detection result by the AE sensor is shown in FIG.

  Specifically, when an acoustic peak of a collision sound as shown in FIG. 6 is detected, it is determined in S4 that the vehicle is in the backstop collision state (S7), and in S6, the valve seat collision state (S9). On the other hand, when the acoustic peak of the collision sound is not detected, it is determined that the vibration state (S8, S10) is in both S4 and S6 (see FIG. 1).

(4) Effects of the present embodiment According to the present embodiment, as described above, the position and behavior of the check valve unit 3 are captured through the position determination process, the behavior determination process, and the collision determination process. The detailed operation state of the check valve 1 can be diagnosed, and the occurrence of deterioration of the swing check valve 1 can be accurately predicted based on the diagnosis result of the detailed operation state.

  In addition, since the position and behavior of the check valve unit 3 can be accurately monitored, it is possible to grasp the progress of the deterioration that has occurred and by comparing it with the operating state of the healthy swing check valve, It is also possible to diagnose an abnormal state such as the check valve unit 3 being dropped or stuck.

In addition, as shown in FIG. 7, even when the ultrasonic sensor 30b is installed below the check valve unit 3 (the bottom surface 21 of the valve box 2), the detailed operating state of the swing check valve 1 is diagnosed. Can do.

  In this case, in the position determination step, when the distance between the ultrasonic sensor 30b and the check valve unit 3 is long, it is determined that the check valve unit 3 is located on the backstop 14 side, and when the distance is short, the position is on the valve seat 12 side. Except for the determination, the operating condition of the swing check valve can be diagnosed in the same procedure as when the ultrasonic sensor is disposed above.

3. Second Embodiment FIG. 8 is a diagram showing an arrangement position of an ultrasonic sensor according to this embodiment. FIG. 8A is a front view of a part of the check valve unit and the valve case of the swing check valve in the fully opened state, and FIG. 8B is a side view of the check valve unit. As shown in FIG. 8, in this embodiment, the ultrasonic sensor 30c is installed on the side surface 22 of the valve box 2, and the specific determination method of the position determination step is different from that of the first embodiment described above. .

  As shown in FIG. 8, when the ultrasonic sensor 30 c is installed on the side surface 22 of the valve box 2, for example, the ultrasonic sensor 30 c is disposed on the upper side (backstop side) of the side surface 22 of the valve box 2. If the reflected echo is measured, it is determined that the check valve unit 3 is located on the backstop side. If it is not measured, the check valve unit 3 is located on the valve seat side or between the backstop and the valve seat. judge.

  In addition, when the ultrasonic sensor 30c is installed on the side surface 22 of the valve box 2, the area where the ultrasonic wave is reflected changes in accordance with the movement of the check valve unit 3, so that the peak height of the reflected echo is measured. Changes with time. Whether or not the check valve unit 3 is moving can be determined based on the change in the peak height for each measurement time.

Even when the ultrasonic sensor 30 c is installed on the side surface 22 of the valve box 2, the period of vibration of the check valve unit 3 can be measured based on the change in the peak measurement time of the reflected echo.
When the period is early, it can be seen that the amount of wear increases in the future, and therefore, the occurrence of deterioration can be predicted more accurately based on the measurement result of the period of vibration.

4). Third Embodiment The diagnosis method according to the present embodiment relates to each of the above-described embodiments in that it includes a deterioration diagnosis step of diagnosing the degree of the deterioration state in addition to the above-described operation state. Different from the diagnostic method.

  Conventionally, in order to diagnose deterioration due to wear of rotating parts or contact parts and corrosion inside the valve, it is necessary to stop the operation of the plant and disassemble the swing check valve. Although it was difficult to diagnose, according to the present embodiment, based on the frequency distribution of the acoustic peak of the collision sound (sudden sound), the deterioration state diagnosis can be performed without disassembling the swing check valve. It can be carried out.

  Specifically, the frequency distribution of the acoustic peak is obtained by performing frequency analysis, for example, Fast Fourier Transform (FFT) analysis on the acoustic peak (see FIG. 9) of the collision sound detected by the AE sensor. An example of the frequency distribution of acoustic peaks obtained by FFT analysis is shown in FIG.

  And the frequency distribution calculated | required like FIG. 10 and the frequency distribution of the collision sound in the healthy state in which the non-return valve unit set beforehand does not deteriorate are compared. At this time, when the diagnosis target is in a healthy state, the angle and speed at which the check valve unit collides with the backstop and the valve seat are substantially constant, so the obtained frequency distribution is substantially the same as the healthy frequency distribution. become.

  On the other hand, when a gap is generated in the rotating part due to deterioration such as wear or corrosion, a large shift occurs in the support shaft or the collision position of the arcuate motion, so that the collision sound changes. In this process, the state of wear deterioration or corrosion deterioration is diagnosed based on the change in the frequency distribution of the acoustic peak accompanying the change in the impact sound.

  Thus, according to the present embodiment, it is possible to appropriately diagnose the deterioration state of the swing check valve without disassembling the swing check valve. For this reason, it is not necessary to stop the operation of the plant for diagnosing the deterioration state and disassemble the swing check valve, which can contribute to the improvement of the operation efficiency of the plant.

1. Diagnosis of operating state (1) Diagnosis method The flow rate of the internal fluid supplied into the valve box is changed to simulate a fully open state, a backstop collision state, a vibration state, and a fully closed state, and the second embodiment described above. The operating state of the swing check valve was diagnosed using the diagnostic method according to the embodiment.

  Specifically, as shown in FIG. 8, the ultrasonic sensor 30 c is arranged on the side of the backstop 14 on the side surface 22 of the valve box 2, and the presence / absence of reflected echo is measured to perform the determination by the position determination process. .

  Next, by fixing the ultrasonic sensor 30c at the same position as in the position determination step, measuring the reflected echo 10 times at intervals of 1 second, and measuring the change in the peak position of the reflected echo every measurement time Judgment by the behavior judgment process was performed.

  And the AE sensor was installed in the bottom part of the valve box 2, and the determination by a collision determination process was performed by detecting the collision sound which arose in the valve box 2. FIG. The above results are shown in FIG.

(2) Diagnosis result Based on the result of the position determination shown in FIG. 11, the reflected echo from the check valve unit can be confirmed in the fully open state, the backstop collision, and the vibration state, and the reflected echo cannot be confirmed in the fully closed state. It was. Thereby, it was confirmed that the rough position of the check valve unit can be diagnosed by the presence or absence of the reflected echo.

  Next, from the results of behavior determination, there is almost no change in the peak position of the reflected echo from the check valve unit in the fully open state and the fully closed state, and the peak position of the reflected echo in the backstop collision state and the vibration state. The intensity and measurement time of each changed with each measurement. Thereby, it was confirmed that the behavior of the check valve unit can be diagnosed based on the change of the peak position of the reflected echo for each measurement time.

  Further, from the result of the collision determination, the acoustic peak of the collision sound was not confirmed in any of the fully open state, the vibration, and the fully closed state, and many acoustic peaks were confirmed in the backstop collision state. Thereby, it was confirmed that the presence or absence of the collision of the check valve unit can be diagnosed using the AE sensor.

2. Diagnosis of deteriorated state (1) Diagnosis method Frequency distribution of collision sound in backstop collision state using a swing check valve in a healthy state and a swing check valve in which the sliding part around the nut is worn. Asked. FIG. 11 (A) shows the frequency distribution of the collision sound of the swing check valve in a healthy state, and FIG. 11 (B) shows the frequency distribution of the collision sound of the swing check valve in which wear occurs on the sliding portion around the nut. Show.

(2) Diagnosis results When comparing FIGS. 11 (A) and 11 (B), a swing check valve in which wear has occurred in the sliding portion is shifted in frequency distribution with respect to a swing check valve in a healthy state. It was confirmed that deterioration due to wear was progressing. Thus, it was confirmed that the degree of deterioration of the swing check valve could be diagnosed by comparing the frequency distribution of the collision sound with the frequency distribution of the collision sound of the healthy swing check valve.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Swing check valve 2 Valve box 3 Check valve unit 4 Valve stick 6 Arm 7 Arm through-hole 8 Valve body 9 Valve body bolt 10 Valve lid 11 Upper surface of the lid 12 Valve seat 14 Back stop 20 Nut 21 Bottom surface of the valve box 22 Side of valve box 30a-30c Ultrasonic sensor

Claims (5)

A check method for a swing check valve for diagnosing the operating state of a swing check valve in which a check valve unit that moves arcuately with a valve stem as a support shaft is housed in a valve box,
A position determination step for determining the position of the check valve unit based on ultrasonic waves that are incident on the valve box and reflected by the check valve unit from an ultrasonic sensor installed in the valve box;
A behavior determination step for determining a state of behavior of the check valve unit based on a change in measurement time of the peak position of the ultrasonic wave measured by the ultrasonic sensor;
A collision that detects an impact sound generated in the valve box using an AE sensor installed in the valve box, and determines whether or not the check valve unit and the valve box collide based on the detected collision sound. A swing check valve diagnostic method comprising: a determination step.   The position determination step is based on ultrasonic waves that are incident on the valve box from an ultrasonic sensor installed above or below the check valve unit in the valve box and reflected by the check valve unit. 2. The swing check valve diagnosis according to claim 1, wherein a distance between the ultrasonic sensor and the check valve unit is measured, and a position of the check valve unit is determined based on the measured distance. Method.   In the position determination step, ultrasonic waves are incident on the valve box from an ultrasonic sensor installed on a side surface of the valve box, and based on the presence or absence of ultrasonic waves reflected by the check valve unit, the check valve unit 2. The swing check valve diagnosis method according to claim 1, wherein the position is determined. The collision sound is detected using the AE sensor, and the frequency distribution of the collision sound is obtained by frequency analysis of the acoustic peak of the detected collision sound,
Deterioration for diagnosing the degree of deterioration of the check valve unit by comparing the obtained frequency distribution of the collision sound with the preset frequency distribution of the collision sound when the check valve unit is not deteriorated The diagnosis method for a swing check valve according to any one of claims 1 to 3, further comprising a diagnosis step. A check method for a swing check valve for diagnosing a deterioration state of a swing check valve in which a check valve unit that moves arcuately using a valve stem as a support shaft is housed in a valve box,
The collision sound generated in the valve box is detected using an AE sensor installed in the valve box, and the frequency distribution of the collision sound is obtained by frequency analysis of the acoustic peak of the detected collision sound.
Deterioration for diagnosing the degree of deterioration of the check valve unit by comparing the obtained frequency distribution of the collision sound with the preset frequency distribution of the collision sound when the check valve unit is not deteriorated A diagnostic method for a swing check valve, comprising a diagnostic step.

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