JPH04296299A - Monitoring method and device for steam trap as well as diagnostic method and device plus manufacturing line thereof - Google Patents

Abstract

PURPOSE:To judge the on-off state of a valve and the presence of something wrong with it easily and accurately without disassembling a steam trap by detecting an acoustic signal with an acoustic sensor set up in the steam trap, and monitoring the valve on the basis of the frequency characteristics and waveform features. CONSTITUTION:An acoustic emission signal being emitted out of a steam trap 1 is detected by an AE sensor 2 and, after being amplified by an amplifier 3, it is inputted into an AE signal feature parameter extraction part (arithmetic processing part) 11. At this time, the AE signal feature parameter extraction part 11 executes a frequency analysis of the AE signal inputted, and this analyzed result is outputted to a trouble judge processing part 12. In succession, at this trouble judge processing part 12, the analyzed result is compared with the setting reference value, performing this trouble judgment. Sunsequently, this trouble judgment result is outputted to a display part 7 for display. With this constitution, a valve on-off state in the steam trap 1 and the presence of something wrong with it is easily and accurately judged without disassembling the steam trap 1.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method and device for monitoring a steam trap, a method and device for monitoring a steam trap, and a method and device for diagnosing a valve abnormality, using an AE (acoustic emission) measurement method. It also relates to a steam trap production line.

0002

2. Description of the Related Art Many relief valves, safety valves, etc. are installed in conventional steam piping systems. If these valves become jammed with foreign matter, steam will leak from the trapped area, creating a flow of steam, which will cause a reduction in thermal efficiency. Therefore, it is important to monitor the operating status of the valve.

Conventionally, as a method for monitoring the operating state of a valve, a vibration method has been known, which is performed by detecting the waveform of vibration of piping, etc., generated by the flow of steam, as described in Japanese Patent Laid-Open No. 17079/1983. It is being

0004

[Problems to be Solved by the Invention] The above-mentioned prior art focuses on the vibration waveform of piping generated by the steam flow flowing through the valve,
The valve abnormality is determined based on the level of the vibration waveform. However, since the valve provided in the steam trap opens and closes once every second, it is difficult to distinguish and detect whether vibrations generated in the steam trap are caused by leaking steam flow or by opening and closing the valve. Therefore, it is difficult to use this conventional vibration method for monitoring steam traps, and even if it is applied, accuracy problems will occur.

[0005] An object of the present invention is to provide a steam trap monitoring method, a monitoring device, etc., which can accurately detect the open/close status of a valve provided in a steam trap and the presence or absence of an abnormality.

[0006]

[Means for Solving the Problems] The above object is to detect the sonic signal generated due to the steam flow due to the opening and closing of the valve or the leaked steam flow using an AE sensor installed in the body or piping of the steam trap, and to This is accomplished by monitoring the valves through their characteristics and waveform characteristics.

[0007]

[Operation] The frequency characteristics and waveform characteristics of the sound waves generated by the steam flow are different from vibrations, and those based on valve opening/closing can be easily distinguished from those based on the steam flow. Therefore, the state of the valve can be monitored based on the frequency characteristics and waveform characteristics of the sound waves. For example, the sound waves caused by steam flow when a normal valve is open are completely different from the sound waves caused by steam flow interruption when the valve is closed. The waveform of the sound wave caused by the steam flow is a waveform that repeats the strength and weakness several times while the valve is open, and is a substantially constant waveform while the steam flow is shut off. Furthermore, the frequency of the sound waves caused by the leaked steam flow generated when the valve catches foreign matter has a characteristic that it has a peak only in a certain frequency range.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to FIGS. 1 to 7. FIG. 1 is a block diagram of a steam trap monitoring device according to a first embodiment of the present invention. In this monitoring device, an AE signal generated from a steam trap 1 is detected by an AE sensor 2 installed in the steam trap 1. The AE signal detected by the AE sensor 2 is amplified by an amplifier 3, and its output is subjected to detection processing by a detector 4. The output of the wave detector 4 is converted into a digital signal by a signal analysis section 5, analyzed and sent to a signal determination section 6. The signal analysis section 5 executes signal analysis processing on the input output signal of the detector 4, and when the analysis result is sent to the signal judgment section 6, the signal judgment section 6 compares the sent analysis value and the The open/closed state of the valve is determined by comparing it with a prepared reference value, and the determination result is displayed on the display section 7. Note that the signal analysis section 5, signal determination section 6, and display section 7 are configured by a general personal computer equipped with an A/D conversion board.

FIG. 2 shows the opening/closing operation of the valve of the steam trap 1 in FIG. 1 and the AE caused by the steam flow corresponding to this opening/closing operation.
2 is a diagram showing the correspondence between a signal (in FIG. 2, the output waveform of the amplifier 3 is shown) and its detected waveform. FIG. The monitoring processing method carried out by the signal analysis section 5 and the signal determination section 6 in FIG. 1 will be specifically explained using FIG. 2. When the valve of the steam trap 1 opens and closes according to the time chart shown in FIG. 2, a steam flow is generated by the opening operation, and the steam flow is cut off by the closing operation. The detection signal of the AE sensor 2 is used to identify whether the valve is in the open or closed state. For this purpose, the output signal of the AE sensor 2 is first amplified by the amplifier 3. This amplified waveform becomes a pulsating waveform that repeatedly rises and falls suddenly when the valve is open, and becomes a substantially constant continuous waveform when the valve is closed. That is, the AE signal appears as a sudden type signal or a continuous type signal depending on whether the valve is opened or closed. Therefore, if the detected AE signal is a sudden type, it can be determined that the valve is in an open state, and if it is a continuous type, it can be determined that the valve is in a closed state.

Next, a method for identifying whether an AE signal is a sudden type or a continuous type will be explained. Figure 3 shows the AE
This is the waveform of a signal that has been amplified and detected and then digitally converted by the signal analysis section 5. First, the average voltage value Vm of the digitally converted waveform is determined using the following equation 1.

[0011]

[Math 1]

Here, n is the number of samplings set by the A/D converter of the signal analyzer 5, and Vi is the voltage value at each sampling point i. Next, the peak voltage value Vp of the portion exceeding the average voltage value Vm obtained from this formula 1
1, Vp2, . . . , Vpi .

[0013]

[Math 2]

Next, from the waveform analysis results using Equations 1 and 2, the waveform determination constant K required to determine whether the AE signal is sudden or continuous is determined using Equation 3 below. .

[0015]

[Formula 3] K=Vp/Vm
...(Math. 3) The signal determination section 6 compares the waveform determination constant K of the formula 3 output from the signal analysis section 5 with a reference value prepared in advance, and determines whether the value of the waveform determination constant K exceeds the reference value. If this occurs, it is a sudden type (valve open state), and if it does not exceed, it is a continuous type (valve closed state).
It is determined that This determination result is transferred to the display section 7, and the determination result is displayed on this display section 7. According to this embodiment,
To accurately monitor whether a steam trap valve is open or closed from the outside without disassembling the steam trap. Therefore, it is possible to select the most suitable steam trap that matches the steam specifications based on the number of valve opening and closing operations.

FIG. 4 is a block diagram of a steam trap monitoring device according to a second embodiment of the present invention. In this monitoring device, the AE signal generated from the steam trap 1 is
It is detected by the E-sensor 2 and amplified by the amplifier 3. The output of the amplifier 3 enters a filter 8 that extracts a specific frequency component, and the arithmetic unit 9 inputs the direct output from the amplifier 8 and this filter 8.
The output of is processed as described in detail later. The output of the calculator 9 is input to the determiner 10, which diagnoses whether or not there is an abnormality in the valve of the steam trap 1 based on the output signal of the calculator 9, and displays the diagnosis result on the display unit 7.

FIG. 5 shows the AE of the steam trap 1 shown in FIG. 4 when it is a normal product and when it is an abnormal product.
FIG. 3 is a diagram illustrating differences in frequency characteristics of signals. When examining the frequency characteristics of the AE signal generated due to an abnormality in the valve of the steam trap 1, as shown in FIG. 5, no characteristic frequency component appears in a normal product with the valve closed. However, in the case of an abnormal product, it can be seen that a specific frequency component, in this example, a 40 kHz component, appears prominently due to the leaked steam flow. Therefore, by comparing the output signal level of the filter 8 for extracting the specific frequency component with the direct output signal level of the amplifier 3, it is possible to diagnose an abnormality in the valve of the steam trap 1. Next, a specific processing method of the arithmetic unit 9 will be explained. The arithmetic unit 9 digitally converts the output signal of the filter 8 and the output signal of the amplifier 3, respectively, and calculates the average voltage value Vm of the waveform of each converted signal using Equation 4 below.

[0018]

[Math 4]

Here, n is the number of samplings set by the A/D converter of the calculator 9, and Vi is the number of samples set at each sampling point i.
is the voltage value at . Next, from the average voltage value of the filter 8 output (this is referred to as Vmf) obtained using the above formula 4 and the average voltage value of the amplifier 3 output (this is referred to as Vma), the AE signal is calculated. An output waveform level determination constant (frequency feature determination constant) α for performing frequency feature determination is determined using the following equation 5.

[0020]

[Formula 5] α=Vmf/Vma
...(Equation 5) The determination constant α obtained by Equation 5 is output to the determination unit 10. In the determiner 10, the determination constant α output from the arithmetic unit 9
The presence or absence of an abnormality in the valve of the steam trap 1 is diagnosed by comparing the value with a reference value prepared in advance. That is, if the value of the determination constant α exceeds the reference value, it is diagnosed as abnormal, and if it does not exceed the reference value, it is diagnosed as normal. This diagnosis result is transferred to the display unit 7 and displayed.

According to this embodiment, the presence or absence of an abnormality in the steam trap valve can be diagnosed with high accuracy from the outside, so that an abnormality in the steam trap valve can be detected early and a decrease in thermal efficiency can be prevented. It is also possible to monitor the valve opening/closing status.

FIG. 6 is a block diagram of a steam trap monitoring device according to a third embodiment of the present invention. This embodiment diagnoses whether or not there is an abnormality in the valve of the steam trap based on the occurrence of a specific frequency of the AE signal in the second embodiment (FIG. 4) described above. In FIG. 6, an AE signal generated from a steam trap 1 is detected by an AE sensor 2, amplified by an amplifier 3, and then input to an AE signal feature parameter extraction section (arithmetic processing section) 11. The AE signal feature parameter extraction unit 11 performs frequency analysis of the input AE signal. The results of this analysis processing are sent to the abnormality determination processing section 12,
The abnormality determination processing section 12 compares the result of the analysis process with a set reference value to determine an abnormality. The abnormality determination result is
The image is transferred to the display section 7 and displayed.

FIG. 7 is a diagram illustrating temporal changes in the frequency components of the AE signal during valve opening/closing operations when identifying normal and abnormal steam traps 1 in this third embodiment. Using FIG. 7, the feature parameter calculation method of the AE signal feature parameter extraction section 11 and the abnormality determination processing method of the abnormality determination processing section 12 in the third embodiment will be specifically explained. When we examine the temporal changes in the frequency components of the AE signals generated from a normal steam trap and an abnormal steam trap, we find that in the case of a normal product, the AE signal corresponds to the opening/closing operation of the valve, as shown in Figure 7. Change, AE
The frequency components of the signal also change over time. On the other hand, in the case of an abnormal product, an AE signal of a specific frequency (40 kHz in this example) is continuously detected even though the valve repeats opening and closing operations. Utilizing this fact, in this embodiment, it is determined whether or not the product is an abnormal product.

The AE signal feature parameter extraction unit 11 extracts the features of the specific frequency generation situation of this AE signal, and in this example, 4 is used as the AE signal feature parameter.
The duration Fd of the specific frequency component of 0 kHz is calculated and determined. The duration Fd of this specific frequency component is determined by calculating the time during which the first peak frequency extracted by the AE signal feature parameter extraction section 11 continuously reaches 40 kHz. In the next abnormality determination processing section 12, A
The duration Fd of the specific frequency component outputted from the E signal feature parameter extraction unit 11 is compared with a reference value, and if the duration Fd exceeds the reference value, it is determined that the valve is abnormal, and if it does not exceed the reference value. is judged to be normal. This diagnosis result is transferred to the display unit 7 and displayed. According to this embodiment, AE
Based on the occurrence of a specific frequency of the signal, it is possible to diagnose from the outside whether there is an abnormality in the steam trap valve. Further, similarly to the present embodiment described above, it is also possible to monitor the opening and closing states of the valves. Although each of the above-mentioned embodiments has been described as a steam trap monitoring device, it goes without saying that even if these are used as a steam trap diagnostic device, the open/close status of the valve and the presence or absence of an abnormality can be diagnosed using the same operation. Nor.

[0025] In a steam trap manufacturing line having an inspection process, a manufacturing line can be constructed in which the steam trap monitoring device and diagnostic device of each of the above embodiments are provided in the steam trap inspection process. This production line can determine the open/closed status of valves and distinguish between normal and abnormal products without disassembling the steam trap.
Since judgment criteria can be set strictly, it is possible to automate the inspection process and improve inspection efficiency and quality control level.

In each of the above embodiments, only an inverted bucket type steam trap has been described, but it goes without saying that the present invention is not limited to this inverted bucket type steam trap.

[0027]

According to the present invention, it is possible to determine whether the valve of the steam trap is open or closed or whether there is an abnormality without disassembling the steam trap. Also, in this judgment,
Since it is possible to provide objective and strict criteria for judgment,
It becomes possible to make judgments tailored to the application. The inspection process of the steam trap production line can be automated, improving inspection efficiency and quality control level.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a steam trap monitoring device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the opening/closing operation and output waveform of the valve in FIG. 1;

FIG. 3 is an explanatory diagram of a detection processing waveform in FIG. 1;

FIG. 4 is a configuration diagram of a steam trap monitoring device according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of frequency characteristics in FIG. 4;

FIG. 6 is a configuration diagram of a steam trap monitoring device according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of temporal changes in frequency components in FIG. 6;

[Explanation of symbols]

1...Steam trap, 2...AE sensor, 3...amplifier,
4... Detector, 5... Signal analysis section, 6... Signal judgment section, 7... Display section, 8... Filter, 9... Arithmetic unit, 10... Judgment device, 11
...AE signal feature parameter extraction unit (arithmetic processing unit), 12
...Anomaly determination processing unit.

Claims (7)

[Claims] 1. A method for monitoring a steam trap, in which an AE sensor installed in the steam trap detects an AE signal generated from the steam trap, and the valve opening/closing state of the steam trap is monitored from the waveform characteristics of the AE signal. Claim 2: An AE sensor that is installed in a steam trap to detect an AE signal generated from the steam trap, a detector that performs detection processing on the detected AE signal, and a waveform characteristic of the AE signal that changes continuously from the detection output. A steam trap monitoring device comprising a signal analysis/judgment unit that determines whether a steam trap valve is in a closed state based on whether or not the steam trap valve is closed, and a display unit that displays the determination result. 3. An AE sensor installed in the steam trap detects an AE signal generated from the steam trap, and diagnoses the valve opening/closing state of the steam trap and the abnormal state of the valve based on the level of a specific frequency of the AE signal. How to diagnose a steam trap. 4. An AE sensor installed in a steam trap to detect an AE signal generated from the steam trap, a filter means for extracting a specific frequency component from the detected AE signal, an output signal level of the filter means, and the filter. a computing unit that computes the output signal level of the previous stage that does not pass through the means; a determining unit that compares the computed value of the computing unit with a reference value and determines from the comparison value whether or not there is an abnormality in the valve of the steam trap; A steam trap diagnostic device comprising a display that displays the determination results. 5. An AE sensor installed in the steam trap detects the AE signal generated from the steam trap, and diagnoses the valve opening/closing status and valve abnormality of the steam trap based on the temporal occurrence of a specific frequency of the AE signal. How to diagnose a steam trap. 6. An AE sensor installed in a steam trap to detect an AE signal generated from the steam trap, an arithmetic processing unit that calculates the duration of a specific frequency component from the detected AE signal, and a specific frequency calculated by the AE sensor. A diagnostic device for a steam trap comprising an abnormality determination processing section that compares the duration of a component with a reference value and determines that an abnormality has occurred in the valve if the duration of the component exceeds the reference value. 7. In a steam trap production line having an inspection step, the steam trap monitoring device or diagnostic device according to claim 2, claim 4, or claim 6 is provided in the inspection step, and the produced steam trap A steam trap production line characterized by inspecting whether the valves of the steam traps are normal or abnormal.