Wireless valve opening degree meter

Abstract

To measure data at the start of valve movement.SOLUTION: A wireless valve opening degree meter 1 comprises: an opening degree measurement unit 11 that measures an opening degree of a valve 2; a wireless communication unit 16 that wirelessly transmits to the outside measurement values obtained by the measurement unit 11; and a sampling control unit 18 that, upon detecting that an electric signal has been output to a solenoid valve 3, which supplies operating air to the valve 2, to set the solenoid valve 3 in an open state or a closed state, determines that the valve 2 starts to move, and switches a sampling period of the measurement values by the measurement unit 11 from an initial value to a faster sampling period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for supporting maintenance work, and more particularly to a wireless valve position meter that realizes support for efficient valve maintenance work. [Background technology]

[0002] Valves are one of the most important pieces of equipment in plants, and are closely related to the safety and efficiency of processes. If a valve suddenly fails, there is a risk of accidents such as explosions and fires, or a decrease in production efficiency due to process shutdowns, so regular maintenance is essential. To improve the efficiency of maintenance, there is a method for attaching valve position meters to valves to acquire data and then analyzing the data to diagnose the valve's condition (Patent Document 1).

[0003] By diagnosing the condition of the valve, it is possible to detect any abnormalities in the valve early and prevent breakdowns before they occur.It is desirable to install a valve position meter to acquire diagnostic data on an existing valve without requiring new wiring work, and a method of retrofitting a battery-powered wireless valve position meter has been proposed.

[0004] Low power consumption is required for battery-powered valve position gauges to be used over long periods of time. To reduce power consumption due to data sampling processing, it is desirable to perform sampling at a low speed when the valve is not operating, and switch to high-speed sampling only while the valve is operating. One possible method for switching the sampling period is to monitor the valve position data and switch to high-speed sampling when the change in position Δ becomes greater than a threshold, as shown in Figure 8. However, this method has the problem of missing data at the start of the valve movement, as the sampling period is switched after the valve has started to move. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7417376 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a wireless valve position meter that can measure data on the start of valve movement. [Means for solving the problem]

[0007] The present invention is characterized in that a battery-powered wireless valve position indicator attached to a valve comprises a measuring unit configured to measure the valve position, a wireless communication unit configured to wirelessly transmit the measurement value obtained by the measuring unit to the outside, and a sampling control unit configured to determine that movement of the valve has begun when it detects that an electrical signal has been output to a solenoid valve that supplies operating air to the valve to switch the solenoid valve to an open or closed state, and to switch the sampling period of the measurement value measured by the measuring unit to a sampling period faster than an initial value.

[0008] The present invention is also characterized in that a battery-powered wireless valve position indicator attached to a valve comprises a measurement unit configured to measure the valve position, a wireless communication unit configured to wirelessly transmit the measurement value obtained by the measurement unit to the outside, a coil installed near a solenoid valve that supplies operating air to the valve, and a sampling control unit configured to determine that movement of the valve will begin when a change in the magnetic field generated by the solenoid valve is detected by the current flowing through the coil, and to switch the sampling period of the measurement value obtained by the measurement unit to a sampling period faster than an initial value.

[0009] In addition, in the wireless valve position meter of the present invention, the sampling control unit is characterized in that, when it determines that the valve has stopped after determining that the valve has started to move, it returns the sampling period to the initial value. In the wireless valve position meter of the present invention, the sampling control unit determines whether the valve has stopped based on the measurement value obtained by the measurement unit. Furthermore, in the wireless valve position meter of the present invention, the measurement unit is characterized in that it measures at least one of the air pressure supplied to the valve's operating device and the temperature on the outlet side of the valve, in addition to the valve position. [Effects of the Invention]

[0010] According to the present invention, when it is detected that an electrical signal that sets the solenoid valve to an open or closed state has been output, it is determined that the valve is about to start moving, and by switching the sampling period, it is possible to measure data on the start of the valve movement.

[0011] Furthermore, in the present invention, when a change in the magnetic field generated by the solenoid valve is detected by the current flowing through the coil, it is determined that the valve is about to start moving, and by switching the sampling period, it becomes possible to measure data on the start of valve movement. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing the configuration of a wireless opening meter according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart illustrating the operation of the wireless opening meter according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart illustrating the operation of the wireless opening meter according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the timing of the electric signal to the solenoid valve, the air pressure of the actuator, and the valve opening. [Figure 5]FIG. 5 is a block diagram showing the configuration of a wireless opening meter according to a second embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart illustrating the operation of the wireless opening meter according to the second embodiment of the present invention. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of a computer that realizes the wireless opening meters according to the first and second embodiments of the present invention. [Figure 8] FIG. 8 is a diagram illustrating a method for switching the sampling period according to a change in the valve opening. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Principle of the Invention] The inventors came up with the idea of ​​obtaining an external trigger to switch the sampling period, rather than switching the data sampling period based solely on information obtained from the valve opening, and came to the conclusion that it would be effective to obtain the trigger from the solenoid valve used to control the air supply to the valve.

[0014] [First Example] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Fig. 1 is a block diagram showing the configuration of a wireless opening meter according to a first embodiment of the present invention. The battery-powered wireless opening meter 1 attached to the valve 2 includes a valve ID memory unit 10 that stores an ID (identification information) unique to the valve 2 to which the wireless opening meter 1 is attached, an opening measurement unit 11 that measures the opening of the valve 2, a pressure measurement unit 12 that measures the air pressure supplied to the actuator of the valve 2, a temperature measurement unit 13 that measures the temperature on the outlet side of the valve 2, a memory unit 14 that stores the opening measurement value, the pressure measurement value, and the temperature measurement value, a fault diagnosis unit 15 that calculates an index of changes that will lead to a fault in the valve 2 based on the measurement value and performs a fault diagnosis of the valve 2 based on the index, a wireless communication unit 16 that wirelessly transmits the index, the results of the fault diagnosis, and the measurement value to an external valve maintenance support device, a signal receiving unit 17 that receives an electrical signal output to the solenoid valve 3, a sampling control unit 18 that sets the sampling period for the measurement values ​​by the measurement units 11 to 13, and a battery 19 that supplies power to each unit of the wireless opening meter 1.

[0015] 2 and 3 are flow charts explaining the operation of the wireless position indicator 1 of this embodiment. Valve 2 is instrumented as shown in Fig. 1, and an electrical signal is sent from control unit 4 to solenoid valve 3 to open it, and when solenoid valve 3 opens, operating air is supplied to an operating device (not shown) of valve 2 via solenoid valve 3, causing valve 2 to move in the direction of increasing or decreasing the opening. The following explanation of the present invention also applies to the operation when solenoid valve 3 is closed.

[0016] In the initial state, the sampling period of the data from the wireless position meter 1 is set to a slow sampling period that corresponds to the case where the valve 2 is not operating. The signal receiving unit 17 of the wireless position meter 1 receives the electrical signal output from the control unit 4 to the solenoid valve 3.

[0017] When the control unit 4 does not output an electrical signal to open the solenoid valve 3 (NO in step S100 in Figure 2), the sampling control unit 18 of the wireless opening meter 1 determines that the valve 2 is not operating and leaves the sampling period at the initial value (slow sampling period).

[0018] Furthermore, when the sampling control unit 18 detects through the signal receiving unit 17 that an electrical signal has been output from the control unit 4 to open the solenoid valve 3 (YES in step S100), it determines that the movement of the valve 2 has started, and switches the sampling period from the initial value to a high-speed sampling period (step S101 in FIG. 2). The switching of the sampling period can be realized, for example, by changing the clock of an AD converter that converts the analog measurement values ​​by the measurement units 11 to 13 into digital signals.

[0019] The opening measurement unit 11 of the wireless valve position meter 1 measures the valve opening, for example, by detecting the rotation angle of the stem (valve rod) of the valve 2 (FIG. 2, step S102). The configuration of such an opening measurement unit 11 (opening sensor) is disclosed in, for example, JP 2021-026268 A, and therefore detailed description thereof will be omitted. The sampling control unit 18 receives the opening measurement value from the opening measurement unit 11, and stores the received opening measurement value and the time of reception of the opening measurement value in the storage unit 14 (Step S103 in FIG. 2).

[0020] The pressure measuring unit 12 of the wireless valve position indicator 1 measures the air pressure supplied to the operating device of the valve 2 (Step S104 in FIG. 2). The sampling control unit 18 receives the pressure measurement value from the pressure measurement unit 12, and stores the received pressure measurement value and the time of reception of the pressure measurement value in the storage unit 14 (Step S105 in FIG. 2).

[0021] The temperature measurement unit 13 of the wireless valve position indicator 1 measures the temperature on the outlet side of the valve 2 (Step S106 in FIG. 2). The sampling control unit 18 receives the temperature measurement value from the temperature measurement unit 13, and stores the received temperature measurement value and the time when the temperature measurement value was received in the storage unit 14 (step S107 in FIG. 2).

[0022] Next, after determining in step S100 that the valve 2 has started to move, the sampling control unit 18 determines whether the valve 2 has stopped (step S108 in FIG. 2). After determining that the valve 2 has started to move, the sampling control unit 18 determines that the valve 2 has stopped, for example, when the opening measurement value received from the opening measurement unit 11 has settled. The settling determination may be made by determining that the valve 2 has stopped when, for example, the change in the opening measurement value per sampling period is equal to or less than a predetermined stop determination threshold.

[0023] When the valve 2 stops, the sampling control unit 18 returns the sampling period to the initial value (low-speed sampling period) (step S109 in FIG. 2). In this way, the opening measurement unit 11, the pressure measurement unit 12, the temperature measurement unit 13, and the sampling control unit 18 perform the processes of steps S102 to S107 at each sampling period set by the sampling control unit 18. By repeating the processes of steps S102 to S107, time series data of the opening measurement values, time series data of the pressure measurement values, and time series data of the temperature measurement values ​​are accumulated in the memory unit 14.

[0024] Next, at a predetermined timing, the failure diagnosis unit 15 of the wireless position indicator 1 calculates an index of changes that will lead to a failure of the valve 2 based on at least one of the time series data of the position measurement values, the time series data of the pressure measurement values, and the time series data of the temperature measurement values ​​stored in the memory unit 14 (step S200 in FIG. 3), and performs a failure diagnosis of the valve 2 based on the index (step S201 in FIG. 3). The failure diagnosis unit 15 may perform the process, for example, when the valve 2 stops, but the process may also be performed at another timing.

[0025] When the technology for detecting scale buildup on the sliding parts of a valve (Patent Document 1) is applied to this embodiment, the fault diagnosis unit 15 uses the dead band time, calculated from the time series data of the pressure measurement value and the time series data of the valve opening degree measurement value, from the time when the actuator air pressure changes until the valve opening degree changes, as an index of changes that may lead to a fault (Step S200). When the dead band time is equal to or greater than a predetermined diagnostic threshold, the fault diagnosis unit 15 determines that there is a possibility that scale buildup has occurred (fault detection), and when the dead band time is less than the diagnostic threshold, it determines that the valve is normal (Step S201).

[0026] When a technology for detecting stick-slip in a valve's sliding portion (Patent Publication No. 3254624) is applied to this embodiment, the fault diagnosis unit 15 calculates the root mean square value and the average value of the valve opening movement amount (information equivalent to speed) during a diagnostic period calculated from time-series data of the valve opening measurement value, and further calculates the ratio Aτ of the average value and the root mean square value (=root mean square value / average value).The fault diagnosis unit 15 uses the difference Aτ-A between this ratio Aτ and a ratio A for a normal state stored in advance as an index of a change leading to a fault (step S200).When the difference Aτ-A is equal to or greater than a predetermined diagnostic threshold, the fault diagnosis unit 15 determines that stick-slip may be occurring (fault detection), and when the difference Aτ-A is less than the diagnostic threshold, the fault diagnosis unit 15 determines that the valve is normal (step S201).

[0027] When a technology for detecting deterioration of a valve's V-packing (Japanese Patent No. 6851938) is applied to this embodiment, the malfunction diagnosis unit 15 uses a valve speed index (maximum operating speed) for the period under diagnosis calculated from time-series data of the valve position measurement values ​​and a valve friction index (pressure difference depending on the valve position direction) for the period under diagnosis calculated from time-series data of the valve position measurement values ​​and time-series data of the pressure measurement values ​​as indicators of changes leading to a malfunction (step S200). When the speed index is equal to or greater than a predetermined speed threshold (diagnosis threshold) and the friction index is equal to or less than a predetermined friction threshold (diagnosis threshold), the malfunction diagnosis unit 15 determines that deterioration of the V-packing may have occurred (step S201).

[0028] When a technology for detecting deterioration of a diaphragm of a valve actuator (Japanese Patent No. 6978252) is applied to this embodiment, the malfunction diagnosis unit 15 uses the product of the valve operation amount (e.g., number of operations or sliding distance) during a period to be diagnosed, calculated from time-series data of the valve opening measurement values, and the average pressure during the period to be diagnosed, calculated from time-series data of the pressure measurement values, as an index of changes leading to a malfunction (step S200).When the calculated product is equal to or greater than a predetermined diagnostic threshold, the malfunction diagnosis unit 15 determines that there is a possibility that deterioration of the diaphragm of the actuator has occurred (step S201).

[0029] When a technology for detecting deterioration (hardening) of the diaphragm of a valve disc (Japanese Patent No. 6981815) is applied to this embodiment, the malfunction diagnosis unit 15 uses the amount of penetration of the valve disc in the closing direction after recognizing that the valve is fully closed, calculated from time-series data of the opening measurement value, as an index of changes that may lead to a malfunction (step S200).When the calculated amount of penetration is equal to or less than a predetermined diagnosis threshold, the malfunction diagnosis unit 15 determines that deterioration of the diaphragm of the valve disc may have occurred (step S201).

[0030] When a technology for detecting deterioration of a part (e.g., looseness of a seat ring) due to a valve's heat cycle (Patent Publication No. 6981816) is applied to this embodiment, the malfunction diagnosis unit 15 calculates the product of the valve temperature difference and the number of cycles over a diagnostic period from time-series data of temperature measurements, and uses this product as an index of changes leading to a malfunction (step S200). When the calculated product is equal to or greater than a predetermined diagnostic threshold, the malfunction diagnosis unit 15 determines that there is a possibility that the part has deteriorated (step S201).

[0031] When a technology for detecting damage to a valve bellows seal (see Japanese Patent No. 7000123) is applied to this embodiment, the fault diagnosis unit 15 determines the relationship between the air pressure required to increase the valve opening and the valve opening (characteristic I) and the relationship between the air pressure required to decrease the valve opening and the valve opening (characteristic II) based on time-series data of the valve opening measurement and time-series data of the pressure measurement. Then, the fault diagnosis unit 15 calculates the absolute value of the difference between characteristic I and a predetermined reference (e.g., characteristic I in a normal state) as the difference on the characteristic I side, and the absolute value of the difference between characteristic II and the reference (e.g., characteristic II in a normal state) as the difference on the characteristic II side. The fault diagnosis unit 15 calculates the difference (absolute value) between the difference on the characteristic I side and the difference on the characteristic II side as an index of a change leading to a fault (step S200). When the calculated index is equal to or exceeds a predetermined diagnostic threshold only in the tension region (low opening region), the fault diagnosis unit 15 determines that the bellows seal may be damaged (step S201).

[0032] When the technology for detecting rupture of a valve bellows seal (Patent No. 7000125) is applied to this embodiment, the malfunction diagnosis unit 15 uses the pressure difference (maximum frictional force) between the air pressure required to increase the valve opening and the air pressure required to decrease the valve opening, calculated from the time series data of the opening measurement value and the time series data of the pressure measurement value, as an index of changes leading to a malfunction (step S200).When the calculated pressure difference becomes equal to or less than a predetermined diagnostic threshold, the malfunction diagnosis unit 15 determines that there is a possibility that the bellows seal has ruptured (step S201).

[0033] The wireless communication unit 16 of the wireless opening meter 1 wirelessly transmits data including the valve ID, opening measurement value, pressure measurement value, temperature measurement value, an indicator of a change leading to a malfunction, and the result of the malfunction diagnosis by the malfunction diagnosis unit 15, which are stored in the valve ID storage unit 10, to a valve maintenance support device (not shown) (step S202 in Figure 3). The valve maintenance support device receives the data transmitted from the wireless valve position meter 1, and presents to the operator an index of the change that led to the malfunction and the result of the malfunction diagnosis.

[0034] As described above, in this embodiment, the electrical signal to the solenoid valve 3 is used as a trigger signal to switch the sampling period. Figure 4 is a diagram showing the timing of the electrical signal to the solenoid valve 3, the actuator air pressure, and the valve opening. t1 indicates the timing at which the sampling period is switched in this embodiment, and t2 indicates the timing in the prior art at which the sampling period is switched when the change in the valve opening becomes greater than a threshold value. In this way, in the prior art, the sampling period is switched after the valve starts to move, whereas in this embodiment, the sampling period can be switched before the valve starts to move, making it possible to measure data at the start of the valve movement.

[0035] [Second Example] In the first embodiment, the wireless position meter 1 and the solenoid valve 3 must be connected by electrical wiring. Therefore, when the wireless position meter 1 is retrofitted, operation of the plant in which the valve 2 is installed may have to be stopped in order to install the wiring between the wireless position meter 1 and the solenoid valve 3. Furthermore, if the plant is in an explosive atmosphere, normalization or other measures will be required. This increases the effort and cost of installation. Therefore, in the second embodiment of the present invention, the change in the magnetic field generated by the solenoid valve is used as a trigger signal.

[0036] 5 is a block diagram showing the configuration of a wireless position meter according to this embodiment. The wireless position meter 1a of this embodiment includes a valve ID storage unit 10, an opening measurement unit 11, a pressure measurement unit 12, a temperature measurement unit 13, a storage unit 14, a malfunction diagnosis unit 15, a wireless communication unit 16, a sampling control unit 18a, a battery 19, a coil 20 installed near the solenoid valve 3, and a current detection unit 21 that detects the current flowing through the coil 20.

[0037] FIG. 6 is a flowchart explaining the operation of the wireless position indicator 1a of this embodiment. The solenoid valve 3 has a mechanism for opening and closing the valve by passing an electric current through a solenoid. Therefore, when an electric signal for opening the solenoid valve 3 is sent from the control unit 4 to the solenoid valve 3, the magnetic field generated by the solenoid valve 3 changes. When the magnetic field generated by the solenoid valve 3 changes, an electric current flows through the coil 20 installed near the solenoid valve 3. The current detection unit 21 of the wireless position indicator 1a detects the current flowing through this coil 20.

[0038] When the sampling control unit 18a of the wireless opening meter 1a cannot detect that current has flowed through the coil 20 (NO in step S100a in FIG. 6), it determines that the magnetic field generated by the solenoid valve 3 has not changed and that the valve 2 is not operating, and leaves the sampling period at the initial value (slow sampling period).

[0039] Furthermore, when the sampling control unit 18a detects through the current detection unit 21 that a current has flowed through the coil 20 (YES in step S100a), it determines that the magnetic field generated by the solenoid valve 3 has changed, determines that the movement of the valve 2 has begun, and switches the sampling period from the initial value to a high-speed sampling period (step S101 in FIG. 6).

[0040] The processing of steps S102 to S109 in Fig. 6 is the same as that described in Example 1. The operations of the failure diagnosis unit 15 and the wireless communication unit 16 are the same as those in Example 1.

[0041] Thus, in this embodiment, the change in the magnetic field generated by the solenoid valve 3 is used as a trigger signal to switch the sampling period. Although electrical wiring is still required between the coil 20 and the wireless position sensor 1a in this embodiment, there is no need for wiring work to extract electrical signals from existing equipment. This embodiment is also superior to the first embodiment in terms of explosion protection. While the response is expected to be slower than when receiving an electrical signal output from the control unit 4 to the solenoid valve 3, this embodiment is expected to be able to detect the start of valve 2 movement more quickly and acquire more data than the prior art, which switches the sampling period when the change in valve position exceeds a threshold value.

[0042] Note that providing a malfunction diagnosis unit in the wireless position gauge 1, 1a is not an essential component of the present invention, and a malfunction diagnosis unit may be provided on the valve maintenance support device side that receives the data. In this case, the wireless communication unit 16 of the wireless position gauge 1, 1a simply wirelessly transmits data including the position measurement value, pressure measurement value, and temperature measurement value to the valve maintenance support device. The measurement value data may be transmitted at each sampling period, or at a period longer than the sampling period.

[0043] Furthermore, in the first and second embodiments, the valve opening, the actuator air pressure, and the temperature on the outlet side of the valve are measured, but it is not necessary to measure all of these, and the present invention can be applied to a battery-powered device that measures at least one of these.

[0044] The valve ID storage unit 10, storage unit 14, fault diagnosis unit 15, wireless communication unit 16, and sampling control unit 18, 18a of the wireless position indicator 1, 1a described in the first and second embodiments can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example configuration of this computer is shown in Figure 7.

[0045] The computer includes a CPU 300, a storage device 301, and an interface device (abbreviated as I / F) 302. The I / F 302 is connected to hardware such as the opening measurement unit 11, the pressure measurement unit 12, the temperature measurement unit 13, the wireless communication unit 16, the signal receiving unit 17, and the current detection unit 21. In such a computer, a program for realizing the present invention is stored in the storage device 301. The CPU 300 executes the processes described in the first and second embodiments in accordance with the program stored in the storage device 301. [Industrial Applicability]

[0046] The present invention can be applied to a technique for assisting valve maintenance work. [Explanation of symbols]

[0047] 1, 1a...wireless opening meter, 2...valve, 3...solenoid valve, 4...control unit, 10...valve ID memory unit, 11...opening measurement unit, 12...pressure measurement unit, 13...temperature measurement unit, 14...memory unit, 15...fault diagnosis unit, 16...wireless communication unit, 17...signal receiving unit, 18, 18a...sampling control unit, 19...battery, 20...coil, 21...current detection unit.

Claims

1. In a battery-powered wireless valve position meter attached to a valve, a measuring unit configured to measure the opening degree of the valve; a wireless communication unit configured to wirelessly transmit the measurement value obtained by the measurement unit to an external device; a sampling control unit configured to determine that movement of the valve will begin when it is detected that an electrical signal has been output to a solenoid valve that supplies operating air to the valve, to switch the solenoid valve to an open or closed state, and to switch the sampling period of the measurement value by the measurement unit to a sampling period faster than an initial value.

2. In a battery-powered wireless valve position meter attached to a valve, a measuring unit configured to measure the opening degree of the valve; a wireless communication unit configured to wirelessly transmit the measurement value obtained by the measurement unit to an external device; a coil disposed near a solenoid valve that supplies actuator air to the valve; a sampling control unit configured to determine that movement of the valve will begin when a change in the magnetic field generated by the solenoid valve is detected by the current flowing through the coil, and to switch the sampling period of the measurement value by the measurement unit to a sampling period faster than the initial value.

3. The wireless opening meter according to claim 1 or 2, The wireless valve position meter is characterized in that the sampling control unit returns the sampling period to the initial value when it determines that the valve has stopped after determining that the valve has started to move.

4. The wireless valve position indicator according to claim 3, The wireless valve position meter is characterized in that the sampling control unit determines whether the valve has stopped based on the measurement value obtained by the measurement unit.

5. The wireless opening meter according to claim 1 or 2, The wireless valve position meter is characterized in that the measurement unit measures at least one of the air pressure supplied to an actuator of the valve and the temperature on the outlet side of the valve, in addition to the opening of the valve.

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