JPH01124739A - Valve leak detector - Google Patents

Abstract

PURPOSE:To correct variation in frequency characteristics of a sensor with time, and to correctly evaluate whether or not a valve leak is caused and also calculates an accurate leak quantity by providing an oscillation body which is characteristically stable nearby an AE (acoustic emission) sensor. CONSTITUTION:The oscillation body 10 provided nearby the AE sensor 2 installed on a valve 1 is supplied with a white noise signal S from an oscillator 11. Then the output of the AE sensor 2 is amplified and filtered by an AE measuring instrument 3 and a frequency spectrum found by a signal analyzing device 4 is stored in a characteristic adjusting device 12 as an analytic result in an initial state. Then when a certain time is elapsed, the frequency characteristics of the AE sensor 2 is measured and the adjustment gain of the characteristic adjuster 12 is found from the difference from the initial state so that the frequency characteristics are similar to those in the initial state, thereby correcting the characteristic variation of the AE sensor. Then when a leak signal is detected, the analyzed frequency spectrum signal is sent to a processor 5 through the characteristic adjuster 12 to decide whether or not the value 1 has a leak.

Description

[Detailed Description of the Invention] [Object of the Invention] <Industrial Applications>
This invention relates to a valve leakage detection device for detecting the presence or absence of leakage and the amount of leakage by using a sensor (referred to as E) to measure ultrasonic waves generated when fluid leaks from a valve seat.

(Prior Art) A large number of valves are arranged in a power generation plant or a chemical process plant for plant control, and these valves are used for flow rate control, pressure control, temperature side W, or system separation.

Among these valves, those that require relatively high pressure fluid shutoff during normal operation of the plant generally require complete shutoff. If there is a leak in the valve, not only will there be a loss of fluid, but high-pressure fluid will remain open for a long time due to foreign objects getting stuck or a slight defect.If detected early, the foreign object can be removed or a simple repair can be performed Things that can be used again may become unusable due to
Repairs etc. will be extremely difficult. Further, there is a problem in that fluid leakage reduces the operating efficiency of the plant, resulting in an increase in plant operating costs. Therefore, in order to detect fluid leakage from a valve at an early stage, a valve leakage detection device as shown in FIG. 3 has conventionally been used.

That is, the leakage signal detected by the AE sensor 2 installed in the valve 1 is amplified by the AE measurement device 3, filtered, and the effective value and frequency spectrum are determined by the signal analysis device 4. The configuration is configured to compare pre-stored frequency spectrum data with frequency spectrum data obtained by analyzing the leakage signal, detect whether or not fluid leakage occurs in the valve 1, and display the result on the output device 6. It has become.

Let the frequency spectrum analyzed by the signal analyzer 24 be a, and the reference frequency spectrum stored in advance in the processing device 5 be b. Then, as shown in the flow diagram of FIG. 4, the processing device 5 compares spectra a and b to obtain the difference C between the spectra, and this difference C is calculated from the reference value α stored in the processing device 5. If it is large, it is determined to be a leakage amount.

By analyzing the leakage signal into its frequency spectrum, detailed signal comparisons can be made.

Further, there is a correspondence relationship between the effective value of the leakage signal obtained by the signal analysis device 4 and the amount of leakage in the valve as shown in FIG. Therefore, by using a configuration such as 0 or more in which the processing device 5 calculates the leakage amount based on this relationship and displays the result on the output device 6, leakage at the valve can be detected early. It can prevent a drop in plant efficiency and reduce damage to the valve body.

(Problem to be solved by the invention) Since the frequency of the amount of leakage in the valve is high and wide, at several tens of KHz or more, an AE (acoustic emission) sensor with high detection efficiency in a high frequency band is used as a sensor. There is. The AE sensor has a structure in which a piezoelectric element is mounted inside to detect ultrasonic waves generated on the mounting surface, and FIG. 6 shows an example of its frequency characteristic a.

However, this frequency characteristic a changes over time, so as time passes, the frequency characteristic changes as shown by the dotted line in Figure 6. When characteristic change 2 occurs, even though leakage occurs in the valve 1, the sensor 2 does not measure it correctly and the signal is processed in the processing device 5. Therefore, the more valve leakage, the more Since it will not be detected unless the leakage becomes large enough, the discovery of the leakage will be delayed.

Furthermore, when calculating the amount of leakage in the valve, there is a problem in that the leakage signal is detected to be low due to changes in the characteristics of the AE sensor, resulting in a decrease in the effective value, making it impossible to determine the correct amount of leakage.

The present invention has been made to solve the above problems,
An object of the present invention is to provide a valve leakage detection device that corrects the change in frequency characteristics of the sensor over time, which is a problem in the valve leakage detection device described above, and can correctly evaluate the presence or absence of valve leakage and accurately calculate the leakage I. be.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a valve leakage detection device for estimating the presence or absence of fluid leakage from a seat portion of a valve and the amount of leakage. an AE sensor, an AE measurement device that measures the output from this AE sensor, a signal analysis device that observes and records the AE waveform and AE spectrum pattern from this AE measurement device, and a signal analysis device that is connected to the output side of this signal analysis device. a processing device for data storage and leakage detection connected to the output side of the characteristic regulator; an output device connected to the output side of the processing device; and an oscillator provided on the seat portion of the oscillator.

(Function) In order to detect changes in the frequency characteristics of the AE sensor over time, a characteristically stable oscillator is provided near the AE sensor, and the oscillator that detects the signal to this oscillator is activated by the signal from the processing device. The oscillator that receives the signal from the 0 oscillator generates vibrations. This vibration is detected by the AE sensor, analyzed by the signal analyzer, and the result is stored in the characteristic adjuster.The signal of the 0 oscillator and the vibration of the oscillator do not change over time, so
If the analysis result of the signal detected by the AE sensor has changed compared to the previous analysis result, the characteristic adjuster adjusts it to match the previous analysis result. Next, when a certain period of time has elapsed, signal analysis is performed using the same means as above. This result is compared with the analysis result stored in the characteristic adjuster, and the tA set value in the characteristic adjuster is determined.
It is possible to provide a valve leakage detection device that is not affected by changes in the characteristics of the E-sensor.

(Embodiment) An embodiment of the valve leakage detection device according to the present invention will be described with reference to FIGS. 1 and 2. Note that the same parts in the figure as in FIG. 3 are indicated by the same reference numerals.

The present invention differs from the conventional example in that an oscillator 1o is provided near the seat portion of the valve 1, and an oscillator 10 that supplies a signal to this oscillator
1 and signal analysis bag fi! The characteristic adjuster 12 is provided between the processing device 4 and the processing device 5.

That is, in this embodiment, as shown in FIG. 1, an oscillator 1O is provided near the AE sensor 2 installed in the valve 1, and an oscillator 10 is connected to the oscillator 10 so that a signal can be supplied from the oscillator 11. The oscillator 10 needs to be placed as close as possible to the AE sensor 2 in order to minimize the influence of the vibrating medium between the oscillator 10 and the 0 oscillator 11. The signal generation from the oscillator 11 is performed by a command signal from the processing device 5. The signal detected by the AE sensor 2 is amplified and filtered by the AE measurement device 3, and the effective value and frequency spectrum are determined by the signal analysis device 4. The analyzed frequency spectrum signal is sent to characteristic adjuster 1.
2, the characteristics are adjusted, and the valve 1 is sent to the processing device.
The presence or absence of leakage is determined. Initial membrane now! In order to obtain the frequency characteristics of the AE sensor in the state, the processing device 5
When an oscillation request signal is supplied to the oscillator 11 from
1 supplies a white noise signal S to an oscillator 10, and the oscillator 10 receives the signal S and oscillates. The reason why white noise is used as a signal is because the leakage signal from the valve occurs in a fairly wide frequency range, so correction of only a specific frequency band is insufficient and correction of a wide frequency band is required. (See FIG. 2) Vibration from the oscillator 10 is converted into an electrical signal by the AE sensor 2, then amplified and filtered by the AE measurement device 3, and the effective value and frequency spectrum are determined by the signal analysis device 4. This frequency spectrum is stored in the characteristic adjuster 12 as an analysis result in the initial state.

Next, when a certain period of time has elapsed, the frequency characteristics of the AE sensor 2 are measured using the same procedure as above.

When the frequency characteristics of the AE sensor 2 change, a difference occurs between the frequency characteristics measured at this time and those measured in the initial state. From this difference, the adjustment gain of the characteristic adjuster 12 is determined so that the frequency characteristic becomes similar to the initial state, and the change in the characteristic of the AE sensor is corrected. This allows A
It becomes possible to detect a leakage signal that is not affected by changes in the characteristics of the E-sensor, and it is possible to correctly determine whether or not leakage has occurred by comparing it with the reference value α. It also becomes possible to estimate the amount of leakage accurately.

Next, the operation of the above embodiment will be described with reference to FIG. Oscillator 11 supplies signal S to oscillator 10 .

The signal S is a calibration signal.The four oscillator 10 receives the signal S from the oscillator 11 and oscillates.

This calibration signal is detected by an AE sensor 2, amplified and filtered by an AE measurement device 3, and an effective value and a frequency spectrum are determined by a signal analysis device 4. The characteristic adjuster 12 compares the frequency spectrum after this time has elapsed with the frequency spectrum in the initial state, calculates an adjustment gain, and corrects the deterioration of the gain of the AE sensor 2. This makes it possible to more accurately detect leakage and estimate the amount of leakage.

This makes it possible to accurately detect leakage and estimate the amount of leakage.

Note that instead of using white noise as the oscillator signal in the above embodiment, the frequency of the signal may be swept from DC to a frequency that requires correction. The configuration of the apparatus in this case is basically the same as that shown in FIG.

After installing the device, in order to obtain the frequency characteristics of the AE sensor in its initial state, when an oscillation request signal is supplied from the processing device 5 to the oscillator 11, the oscillator 11 changes the frequency from DC to the frequency that requires correction as the device. 11 supplies the oscillator 10 with a signal whose frequency sweeps from DC to a frequency that requires correction as a device (hereinafter referred to as a sweep signal).

The oscillator 10 oscillates in response to the sweep signal, and the oscillator 10
The vibrations from are converted into electrical signals by the AE sensor 2, then amplified and filtered by the AE measurement device 3, and the effective value and frequency spectrum are determined by the signal analysis device 4. This frequency spectrum is stored in the characteristic adjuster 12 as an analysis result in the initial state.

Next, when a certain period of time has elapsed, the frequency characteristics of the AE sensor are measured using the same procedure as above. If the characteristics change, this is corrected using the characteristics adjuster. This allows A
It becomes possible to measure leakage signals that are not affected by changes in the characteristics of the E-sensor, and it becomes possible to accurately detect the occurrence of leakage and estimate the amount of leakage.

[Effects of the Invention] According to the present invention, by correcting the deterioration of the AE sensor with the characteristic adjuster, it is possible to prevent the performance deterioration of the valve leakage detection device and to always obtain the correct amount of leakage from the valve. be.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the valve leakage detection device according to the present invention, Fig. 2 is a flow diagram for explaining the operation in Fig. 1, and Fig. 3 is a block diagram showing an embodiment of the valve leakage detection device according to the present invention. 4 is a flow diagram for explaining the action in FIG. 3, and FIG. 5 is a characteristic diagram showing the relationship between the leakage amount and effective value determined by the signal analysis device in FIG. FIG. 6 is a characteristic diagram showing the relationship between the gain and frequency of the AE sensor in FIG. 3. 1... Valve 2... AE sensor 3... AE measuring device 4... Signal analysis device 5... Processing device 6... ... Output device 10 ... Oscillator 11 ... Oscillator 12 ... Characteristic adjuster agent Patent attorney Nori Chika Ken Yudo Daishimaru Kenkan 1: 2nd = Fig. 4 Fig. 5 Circle 5 anti-N f Fig. 6

Claims (1)

[Claims] In a valve leakage detection device that estimates the presence or absence of fluid leakage from a valve seat and the amount of leakage, an AE (acoustic emission,
(hereinafter referred to as AE) sensor, an AE measuring device that measures the output from this AE sensor, and an A sensor that measures the output from this AE sensor;
A signal analysis device for observing and recording E waveforms and AE spectrum patterns, a processing device for storing output data and detecting leakage connected to the output side of this signal analysis device, and an output device connected to the output side of this processing device. A valve leakage detection device comprising: an oscillator provided on the seat portion of the valve via an oscillator from the processing device.