JP2007107897A - Gas leakage detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect gas leakage not only for a micro flow rate but also a large flow rate or a constant flow rate even in the case, the subject is limited to gas piping for supplying gas to collective housing. <P>SOLUTION: The gas leakage detector 5 of this invention is for detecting gas leakage of the piping branched from gas supply source to gas consumer and the gas leakage at each gas consumer composed of an ultrasonic gas flow rate detection means 6 and the gas leakage determination means 7 for determining whether the gas leakage is existing or not based on the gas flow rate detected by the gas flow rate detection means 6. The gas leakage detection means 6 determines micro flow rate leakage if more than the predetermined detection is continued longer than the first determination time, determines same flow leakage if same flow rate detection within predetermined width continued longer than the second determination time, and determines large flow rate leakage if more than the prescribed large flow rate continued longer than the third determination time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas pipe branching from a gas supply source to each gas use destination and a gas leak detection device that detects a gas leak at each gas use destination.

  FIG. 15 is an explanatory diagram of conventional gas leak detection. Conventionally, a gas pipe branched from a gas supply source to each gas use destination, for example, a gas pipe branched from an LP gas cylinder 1, 1,... Alternatively, when detecting a gas leak at each gas usage destination, the membrane gas flow meter 501 is disposed by bypassing from the gas pipe 101 connected to the pressure regulator 91 of the gas supply source, and the membrane gas flow meter In 501, a normal gas flow rate is measured, and a gas leak is detected using the measurement result. In this case, since the gas flow rate is measured using a measuring chamber, it cannot be measured in real time, the gas flow rate measurement itself takes about 1 hour, the measurement takes time, and the accuracy of the measurement data For example, it took about 30 days to detect a gas leak at a minute flow rate. Further, when the gas leak is a large flow rate or the same flow rate, it is difficult to distinguish between the case of the gas leak and the case of using the gas equipment, so that the gas leak cannot be detected. In particular, gas leak detection in gas piping systems that supply gas to apartment buildings was possible with very small flow rates, but it was difficult to detect gas leaks with large flow rates or the same flow rate, and no measures were taken. It was.

  The present invention has been proposed in view of the above, and can detect a gas leak in a short time, and even when targeting a gas piping system that supplies gas to a housing complex, not only a minute flow rate but also a large flow rate is provided. Another object of the present invention is to provide a gas leakage detection device that can accurately detect gas leakage at the same flow rate.

  In order to achieve the above object, the invention according to claim 1 is directed to a gas pipe branching from a gas supply source to each gas use destination and a gas leak detection for detecting a gas leak at each gas use destination. In the apparatus, an ultrasonic gas flow rate detecting means connected in series to a gas pipe before branching of a gas supply source and detecting a gas flow rate at a downstream gas pipe and each gas use destination, and the gas flow rate detecting means Gas leakage determination means for determining whether or not there is a gas leakage based on the gas flow rate detected by the gas leakage detection means, wherein the gas leakage determination means detects a predetermined minute flow rate or more for a first determination time or more. When it is continuous, it is determined that the flow rate is very small, and when the same flow rate within the predetermined width is detected for the second determination time or more, it is determined that the flow rate is the same. When a large flow rate leaks Is shall.

  In the gas leak detection device according to the present invention, since the gas leak of the gas piping system for supplying gas to the housing complex is detected and detected using the ultrasonic gas leak discriminating means, the gas flow from the minute flow rate to the large flow rate is detected. The gas flow rate can be detected accurately in real time, and the gas leakage can be detected in a short time based on the detected gas flow rate. In addition, the real-time data is accumulated, and based on the accumulated data, when the detection of a predetermined minute flow rate or more continues for the first determination time or more, it is determined as a minute flow rate leak, and the same flow rate within a predetermined width is detected. Is determined to be the same flow rate leakage when it continues for more than the second determination time, and it is determined to be a large flow leakage when detection over a predetermined large flow rate continues for more than the third determination time. Large leaks and gas leaks at the same flow rate can be accurately detected.

  Therefore, it is possible to accurately detect gas leaks of various gas consumption patterns that occur in the entire gas piping system including gas equipment used in apartment houses, houses, offices, etc. that supply gas. .

  And even if the number of houses covered by the gas piping system is increased or decreased, for example, in the case of 2 houses or 500 houses, the judgment value can be made variable according to the increased or decreased number of houses or the gas usage situation, Gas leakage can be appropriately determined for each situation.

  FIG. 1 is a view showing a gas piping system to which a gas leakage detection device of the present invention is applied. In the figure, the gas piping system 10 supplies the LP gas from the LP gas cylinders 1, 1,... To the households 3a, 3a,. The gas pipe 11 before branching of the gas supply source, the gas pipe 12 branched from the gas pipe 11, and each gas device of the gas supply destination.

  In the gas pipe 11 before branching, a pressure regulator 9 provided in common on the outlet side of the LP gas cylinders 1, 1,... And a gas leak detection device 5 on the rear stage side of the pressure regulator 9 are provided. Are provided in series.

  2A and 2B are diagrams showing a first configuration example of the gas leakage detection device, where FIG. 2A shows the entire device, and FIG. 2B shows a gas flow rate detection unit. The gas leak detection device 5 is constructed in an electronic gas meter arranged in the gas pipe 11, and an ultrasonic gas flow rate detection unit (gas flow rate detection means) 6 and measurement data of the gas flow rate detection unit 6 are stored in the gas leak detection device 5. And a control unit 7 for processing.

  Inside the gas leak detection device 5, as shown in FIG. 2 (a), a gas pipe 11 is provided transversely so that the gas flows straight. As shown in FIG. 2B, a gas flow rate detection unit 6 is configured by two ultrasonic sensors 61 and 62 provided so as to face the gas pipe 11 diagonally. Measures the flow rate of the gas flowing in the gas pipe 11 according to the measurement principle described later. The ultrasonic sensors 61 and 62 are used as means for transmitting and receiving ultrasonic waves.

  FIGS. 3A and 3B are diagrams showing a second configuration example of the gas leakage detection device, where FIG. 3A shows the entire device, and FIG. 3B shows a gas flow rate detection unit. In the second configuration example, components that are substantially the same as those in the first configuration example are given the same reference numerals, and descriptions thereof are omitted.

  The gas leak detection device 5 of the second configuration example is different from the first configuration example described above in that the gas pipe 11 is provided in a U-shape, and the two ultrasonic sensors 61 and 62 are the gas pipes. It is the point provided so that it may diagonally oppose the 11 U-shaped bottom part.

  In the gas leak detection device 5 of the first and second configuration examples described above, the control unit 7 obtains the gas flow rate based on the measurement result from the gas flow rate detection unit 6, and the measurement principle is roughly as follows. It is a thing.

  First, the ultrasonic arrival time T1 from the upstream to the downstream of the gas flow and the arrival time T2 from the downstream to the upstream are measured using the ultrasonic sensors 61 and 62 arranged in the gas pipe 11.

On the other hand, the arrival times T1 and T2 include the sound velocity C, the gas flow rate U, the distance (propagation distance) L between the ultrasonic sensors 61 and 62, the straight line connecting the ultrasonic sensors 61 and 62, and the direction in which the gas flows. The angle θ formed is expressed by the following formulas (1) and (2).

From the above equations (1) and (2), the gas flow velocity U can be obtained by the following equation (3).

  As can be seen from the above equation (3), the gas flow velocity U is not affected by the sound speed or temperature, and the measured arrival times T1 and T2 and the installation conditions of the ultrasonic sensors 61 and 62, L and θ, are determined. It can be obtained using.

The gas flow rate Q can be obtained by the following equation (4) using the gas flow velocity U and the cross-sectional area S of the gas pipe (gas flow path) 11. This gas flow rate Q is not an integrated value but an instantaneous flow rate at the time of measurement.

  The control unit 7 operates centering on the microcomputer, is configured to include a function of operating the CPU according to the software according to the present invention stored in the memory, and executes the gas leakage determination unit according to the present invention. That is, the control unit 7 obtains the measurement result from the gas flow rate detection unit 6, performs the above calculation, obtains the current gas flow rate Q in real time, and stores and accumulates the data in the memory in time series. Then, gas leak detection is performed based on the data.

  Hereinafter, the gas leakage detection will be described.

  When the gas flow rate Q exceeds a preset reference gas flow rate and is continuously detected for a preset time or longer, the control unit 7 detects the gas pipe system 10 (the gas pipes 11 and 12 and the gas supply destination). It is determined that there is a gas leak in each gas appliance. Further, when the gas flow rate Q falls within a preset predetermined width, the gas piping system 10 (gas pipes 11, 12,...) Is detected when a state within the predetermined width is continuously detected for a preset time or longer. It is determined that a gas leak has occurred in each gas appliance at the gas supply destination.

  FIG. 4 is an explanatory view of the minute leak detection. When the gas flow rate Q is detected exceeding a very small reference gas flow rate QLs, here 3 liters / hour, the control unit 7 determines that the detection time is a predetermined determination time (first determination time) TLs. If it continues for more than (for example, 45 hours), it is determined that there is a slight leak in the gas piping system 10.

  According to this gas leak determination method, even when gas is used in, for example, 2 to 500 houses, such as an apartment house, it is possible to accurately detect minute gas leaks that occur in the entire gas piping system 10.

  FIG. 5 is an explanatory diagram of detection of large flow rate leakage. When the gas flow rate Q is detected exceeding a large reference gas flow rate QHs, here, 500 liters / hour, the control unit 7 determines that the detection time is a predetermined determination time (third determination time) THs ( For example, when it continues for 7 hours or more, it is determined that there is a large flow rate leak in the gas piping system 10.

  According to this gas leakage determination method, even when gas is used in, for example, 2 to 500 houses such as in an apartment house, it is possible to accurately detect a large flow of gas leakage generated in the entire gas piping system 10. .

  FIG. 6 is an explanatory diagram of the same flow rate leak detection. When the gas flow rate Q falls within a preset predetermined width Ws, here 10% (± 5%), the control unit 7 sets the state within the predetermined width to a preset time (second determination). Time) When it is detected continuously for TWs (for example, 2 hours) or more, it is determined that a gas leak has occurred in the gas piping system 10 (gas piping 11, 12). In FIG. 6, pattern A corresponds to a large flow rate gas leak detected when the gas pipe is completely cut, for example, and pattern B is used when the gas is almost not used or the gas equipment is turned off. Corresponds to gas leakage at the same flow rate that is detected when forgotten.

  According to this gas leak determination method, if a gas flow rate of a predetermined width continues, for example, in a late-night time period when the gas is not used in 2 to 500 houses, such as an apartment house, the gas leaks into the gas piping system 10 Therefore, it is possible to accurately detect gas leakage from a small amount to a large amount by using a time period in which almost no gas is used.

  In the control unit 7, reference gas flow rates QLs, QHs and corresponding determination times TLs, THs are set in advance, and the actual gas flow rate Q is compared with them to determine whether there is a slight gas leak in the gas piping system 10. It is determined whether or not there is a gas leak at the flow rate. Further, a predetermined width Ws and a determination time TWs corresponding to the predetermined width Ws are set in advance, and the actual gas flow rate Q is compared with them to determine whether or not there is a gas leakage of substantially the same flow rate in the gas piping system 10.

  As described above, in the present invention, the ultrasonic gas flow rate detection unit 6 connected in series to the gas pipe 11 before branching of the gas supply source is used, and the gas pipes 11 and 12 in the subsequent stages and the respective gas usage destinations. Since gas leakage is detected, the gas flow rate from minute flow rate to large flow rate can be detected accurately in real time, and the gas leakage can be detected in a short time based on the detected gas flow rate. . Further, not only a minute flow rate but also a large flow rate and a gas leak at the same flow rate can be accurately detected.

  Therefore, it is possible to accurately detect various patterns of gas leakage that occur in the entire gas piping system 10 including gas equipment used in apartment houses, houses, offices, and the like that supply gas.

  When the number of houses covered by the gas piping system 10 is, for example, 2 or 500, the reference gas flow rates QLs and QHs, the predetermined width ΔW, The determination times TLs, THs, and TWs (hereinafter collectively referred to as “determination time TM”) can be reviewed and set to an optimal value as appropriate, and gas leakage to the gas piping system 10 is appropriately determined for each situation. Can do.

  Next, a method for setting the determination time TM (TLs, THs, TWs) will be described.

  FIG. 7 is a diagram showing a gas usage state detected by the gas leakage detection device. The vertical axis in FIG. 7 indicates the gas flow rate Q, and the horizontal axis indicates the elapsed time T in the learning period prepared for setting the determination time. When the gas use state detected by the gas leak detection device 5 in the learning period is as shown in FIG. 7, the time that the gas is continuously used (gas use duration) is TA> TB. > TC, and gas is continuously used for the longest time in waveform A. The determination time TM is set by adopting the longest gas use duration TA. That is, the determination time TM is obtained by multiplying the longest gas use duration TA by a predetermined safety factor (for example, 2 to 10). Further, the monitoring upper limit level Tu is obtained by multiplying the longest gas use duration TA by a coefficient (for example, 1.2) smaller than the safety coefficient used when the determination time is set. Further, the monitoring lower limit level Td is obtained by multiplying the longest gas use duration TA by a coefficient (for example, 0.8) smaller than the coefficient used at the time of setting the monitoring upper limit level. Details of the monitoring upper limit level Tu and the monitoring lower limit level Td will be described later.

  There are three types of the determination time TM, the determination time TLs at the time of a slight gas leak, the determination time THs at the time of gas leakage at a large flow rate, and the determination time TWs at the time of gas leakage at substantially the same flow rate. 7 also changes as follows according to the determination time. That is, when the determination time TLs at the time of a minute gas leak is obtained, it is as shown in FIG. 8, and the target waveforms A, B, and C are continuously detected by the gas leak detector 5 during this learning period. Of the waveforms of the gas flow rate Q, the waveform when the reference gas flow rate QLs is exceeded is obtained.

  Further, when the determination time THs at the time of gas leakage at a large flow rate is obtained, it is as shown in FIG. 9, and the target waveforms A, B, and C are continued by the gas leakage detection device 5 during this learning period. Of the detected gas flow rate Q waveforms, the waveform is when the reference gas flow rate QHs is exceeded.

  Further, when obtaining the determination time TWs at the time of gas leakage at substantially the same flow rate, it is as shown in FIG. Among the waveforms of the gas flow rate Q detected in this way, the waveform of the gas flow rate is continuously contained within the predetermined width ΔW. In FIG. 10, QW1 is a lower limit value of the gas flow rate that falls within the predetermined width ΔW, and QW2 is an upper limit value thereof.

  As described above, the determination time TM is set using the gas flow rate Q in the learning period, but the control unit 7 automatically updates the determination time TM in the subsequent normal use period. This update method will be described.

  FIG. 11 is an explanatory diagram of a determination time update method. The vertical axis in FIG. 11 represents the longest gas use duration Tk (hereinafter referred to as “longest period Tk”) in a certain period (for example, 24 hours per day), and the horizontal axis represents the elapsed time (for example, days) T. This period maximum time Tk corresponds to the longest gas use duration TA in FIG.

  The control unit 7 compares the maximum time period Tk obtained this time with the above-described determination time TM, the monitoring upper limit level Tu, and the monitoring lower limit level Td, and as shown in the position (a) of FIG. When the time Tk is a value between the monitoring lower limit level Td and the monitoring upper limit level Tu, the determination time TM is not updated.

  Next, as shown in FIG. 11B, when the longest time period Tk that is smaller than the determination time TM but larger than the monitoring upper limit level Tu has occurred, the incremental re-learning mode is entered as shown in FIG. The elapsed time from the time point A is counted, and when the longest time period Tkb that is smaller than the determination time TM but larger than the monitoring upper limit level Tu occurs again within a predetermined period (here 7 days), at that time point B, The longer period maximum time Tkb is adopted as the longest gas use continuation time between the period maximum time Tka and the period B maximum period Tkb, and the determination time TM is multiplied by a predetermined safety factor (for example, 2 to 10). Update asking. In the incremental relearning mode, when the longest time period Tkb that is smaller than the determination time TM but larger than the monitoring upper limit level Tu does not occur, the incremental relearning mode is terminated and the determination time TM is not updated.

  Next, when the longest time period Tk that is smaller than the monitoring lower limit level Tu occurs as shown in the position (c) of FIG. 11, the re-learning mode is entered as shown in FIG. When the state where the maximum period time Tk is smaller than the monitoring lower limit level Td continues for a predetermined period (here, 28 days), the maximum period maximum time Tkf from the point E to the predetermined period is set to the longest gas. Adopted as the duration of use, the determination time TM is obtained and updated by multiplying by a predetermined safety factor (for example, 2 to 10). In the decrease relearning mode, when the longest period Tkb longer than the monitoring lower limit level Td occurs, the decrease relearning mode is terminated and the determination time TM is not updated.

  Further, when the maximum period time Tk exceeds the determination time TM as in the position (d) of FIG. 11, it is determined that gas leakage has occurred at that time.

  Thus, since the determination time TM can be automatically updated and optimized according to the increase / decrease in the number of houses and the gas consumption pattern, early gas leakage detection can be performed.

  Further, by automatically updating the determination time TM, the determination time TM can be set to an optimum value with respect to the current state, and gas leak detection can be performed with high accuracy.

  Next, another automatic updating method for the determination time TM will be described.

  FIG. 14 is an explanatory diagram of another automatic update method of the determination time TM. The vertical axis in FIG. 14 indicates time, and the horizontal axis indicates elapsed time (in this case, days). In FIG. 14, the staircase-shaped thick solid line represents the determination time TM, and the staircase-shaped broken line represents the longest gas use duration Tn (hereinafter referred to as “longest period time Tn”) in a certain period (for example, 7 days). Yes. Here, the elapsed time changes as L1 (for example, 7 days) → L2 (for example, 7 days) → L3 (for example, 7 days) → L4 (for example, 7 days), and the determination time TM is accordingly TM1 → TM2 → TM3 → TM4 changes, and the longest period Tn changes from Tn1 → Tn2 → Tn3 → Tn4.

Here, the determination time TM3 is obtained and automatically updated according to the following equation (5).

  That is, the longest time Tn2 in the previous predetermined period L2 obtained by measurement is multiplied by the safety factor, and the longest period Tn2 in the previous predetermined period L2 with respect to the longest period Tn1 in the previous predetermined period L1. By multiplying the ratio (adjacent ratio), the determination time TM3 is obtained and automatic updating is performed.

The determination time TM4 is obtained and automatically updated according to the following formula (6).

  That is, the longest time period Tn3 in the previous fixed period L3 obtained by measurement is multiplied by the safety factor, and the longest period time Tn3 in the previous fixed period L3 with respect to the longest period time Tn2 in the previous fixed period L2. By multiplying the ratio (adjacent ratio), the determination time TM4 is obtained and the automatic update is performed.

  As described above, in this automatic update method, the new determination time TM is obtained by multiplying the longest time in the previous period by the safety factor and the adjacent ratio. Therefore, the determination time TM can be changed in accordance with the change of the usage time throughout the year, and the gas leakage can be detected accurately corresponding to the change of the gas usage time in spring, summer, autumn and winter. In addition, the determination time TM can be determined without being affected by a unique value.

  In the above description, the adjacency ratio is obtained by using the longest period time Tn. However, the adjacent ratio may be obtained by using the average value of each gas use duration in a certain period instead of the longest period time Tn. Good.

  In the above description, the adjacency ratio is obtained based on the latest data (previous and previous data). However, since the gas consumption pattern is similar in the same period, for example, one year ago, It is good also as a structure which calculates | requires adjacent ratio based on the data of one year ago, and updates determination time TM using the adjacent ratio.

It is a figure which shows the gas piping system with which the gas leak detection apparatus of this invention is applied. It is a figure which shows the 1st structural example of a gas leak detection apparatus, (a) has shown the whole apparatus, (b) has shown the gas flow volume detection part. It is a figure which shows the 2nd structural example of a gas leak detection apparatus, (a) has shown the whole apparatus, (b) has shown the gas flow volume detection part. It is explanatory drawing of a minute leak detection. It is explanatory drawing of a large flow rate leak detection. It is explanatory drawing of the same flow rate leak detection. It is a figure which shows the gas use condition which the gas leak detection apparatus detected. It is a figure which shows the waveform in the case of calculating | requiring determination time TLs at the time of slight gas leakage. It is a figure which shows the waveform in the case of calculating | requiring the determination time THs at the time of the large-flow gas leak. It is a figure which shows the waveform in the case of calculating | requiring the determination time TWs at the time of the gas leak of substantially the same flow rate. It is explanatory drawing of the update method of determination time. It is explanatory drawing of the determination time automatic update by the increase relearning mode. It is explanatory drawing of the determination time automatic update by the decrease relearning mode. It is explanatory drawing of the other automatic update method of determination time. It is explanatory drawing of the conventional gas leak detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas cylinder 3 Apartment house 3a Each household of an apartment house 4 House 5 Gas leak detector 6 Gas flow detection part (gas flow detection means)
7 Control unit (gas flow rate detection means, gas leak detection means)
9 Pressure regulator 10 Gas piping system 11 Gas piping 12 Gas piping 61 Ultrasonic sensor 62 Ultrasonic sensor

Claims (1)

In a gas pipe that branches from the gas supply source to each gas user and a gas leak detection device that detects gas leaks at each gas user,
An ultrasonic gas flow rate detecting means connected in series to the gas pipe before branching of the gas supply source, and detecting the gas flow rate at the latter gas pipe and each gas usage destination;
Gas leakage determination means for determining whether or not there is a gas leakage based on the gas flow rate detected by the gas flow detection means,
The gas leakage determining means determines that the flow rate is a small flow rate when the detection of a predetermined minute flow rate or more continues for the first determination time or longer, and is the same when the detection of the same flow rate within the predetermined width continues for the second determination time or longer. It is determined that the flow rate is leaking, and it is determined that the flow rate is leaking when detection of a predetermined large flow rate or more continues for a third determination time or more.
A gas leak detection device characterized by that.

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