JP4685582B2 - Gas leak detection device - Google Patents

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.

  Conventionally, when detecting a gas leak in a gas piping system branched from a gas supply source to each gas user, the leak judgment value is not updated for 30 days and is operated in a fixed state. Yes.

  On the other hand, in gas piping systems that diverge toward apartment buildings, gas consumption patterns may change significantly, especially during periods of high temperature / temperature changes, such as at the turn of the season. If the judgment value is fixed for a long time, it becomes impossible to respond to the change in the situation. For this reason, it is the present condition that appropriate gas leak detection cannot be performed.

  The present invention has been proposed in view of the above, and an appropriate leak judgment value can be set in accordance with a change in gas consumption pattern depending on the season of an apartment house, etc. An object of the present invention is to provide a gas leakage detection device capable of detecting gas leakage in a gas piping system.

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 Monitors the longest period of time that is the longest continuous detection time in a certain period of continuous detection time when continuously detecting a gas flow rate greater than or equal to a predetermined flow rate, and multiplies the longest period of time in the previous certain period by a safety factor, Furthermore, the leakage judgment level setting means that sets the leakage judgment level by multiplying the ratio of the longest period in the previous fixed period to the longest period in the previous fixed period, and the longest period in this fixed period And leakage If the determination level over a period maximum time has occurred are those comprising a gas leak discriminating means for discriminating a gas leak, a.
The invention according to claim 2 is a gas supply source in a gas pipe branching from a gas supply source to each gas usage destination and a gas leak detection device for detecting gas leakage at each gas usage destination. Are connected in series to the gas pipe before branching, and the ultrasonic gas flow rate detecting means for detecting the gas flow rate in the subsequent gas pipe and each gas usage place, and the gas flow rate detecting means are within a predetermined width. Monitors the longest period of time that is the longest continuous detection time in a certain period of the continuous detection time when the gas flow rate is continuously detected, multiplies the longest period of time in the previous certain period by a safety factor, and then a certain period of time Leakage judgment level setting means to obtain the leak judgment level by multiplying the ratio of the longest period of time in the previous period and the longest period of time in the previous fixed period, and the longest period of time in the fixed period this time, More than If during the longest time has occurred, those comprising a gas leak discriminating means for discriminating a gas leak, a.

  In the gas leak detection device of the present invention, when continuously detecting a gas flow rate of a predetermined flow rate or more during a certain period of time before the previous time, the longest continuous detection time during the previous fixed time period and a gas flow rate of a predetermined flow rate or more during the previous fixed period Since the ratio of the longest continuous detection time in the previous fixed period when continuously detecting is multiplied by the preset leakage determination level, the leakage determination level is updated to be the new leakage determination level. Appropriate leak judgment level (judgment time) can be set according to changes in gas consumption patterns depending on the season, such as in apartment buildings, and accurate gas leak detection according to the situation can be performed based on the leak judgment level it can.

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

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 is configured to include a function that operates around a microcomputer and operates by the CPU according to the software stored in the memory according to the present invention. The gas flow rate detection unit and the leakage determination level update unit according to the present invention. Is running. In this control unit 7, the measurement result from the gas flow rate detection unit 6 is obtained, the above calculation is performed to obtain the current gas flow rate Q in real time, the data is stored and accumulated in the memory in time series, 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 minute reference gas flow rate QLs, here 3 liters / hour, the control unit 7 continues the detection time for a predetermined determination time TLs (for example, 45 hours) or more. Then, 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 continues for a predetermined determination time THs (for example, 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 determines that the state within the predetermined width is a preset time TWs (for example, 2 hours). When it is continuously detected, 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.

  In this way, gas leakage at the downstream gas pipes 11 and 12 and each gas usage is detected using the ultrasonic gas flow rate detection unit 6 connected in series to the gas pipe 11 before branching of the gas supply source. Thus, the gas flow rate from the minute flow rate to the large flow rate can be detected with high accuracy 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. In this learning period, when the gas usage state detected by the gas leak detection device 5 is in a state as shown in FIG. 7, the time that the gas is continuously used (gas usage duration time, continuous detection time) is , TA> TB> TC, and the gas is continuously used in the waveform A for the longest time. The determination time (leakage determination level) TM is set by adopting this 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 the determination time TWs at the time of gas leakage at substantially the same flow rate is obtained, it is as shown in FIG. 10, and the target waveforms A, B, and C are continued by the gas leakage detection device 5 during this learning period. 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, the monitoring upper limit level Tu, and the monitoring lower limit level Td are set using the gas flow rate Q in the learning period. In the control unit 7, the determination time TM, The monitoring upper limit level Tu and the monitoring lower limit level Td are automatically updated. This update method will be described below.

  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. Further, the monitoring upper limit level Tu and the monitoring lower limit level Td are obtained and updated by multiplying the longest time period Tnb by a coefficient. 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 addition, the monitoring upper limit level Tu and the monitoring lower limit level Td are obtained and updated by multiplying the longest period Tnf by a coefficient. 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 and the like are 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.

  In addition, an appropriate determination time TM can be set according to the scale of the housing complex and the gas consumption pattern, and accurate gas leakage detection according to the situation can be performed based on the determination time TM.

  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 accurately and accurately.

  Next, another automatic updating method for the determination time TM will be described. The automatic update of the determination time TM is performed by the leakage determination level update means according to the present invention configured in the control unit 7.

  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.

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, leak determination level update means)
9 Pressure regulator 10 Gas piping system 11 Gas piping 12 Gas piping 61 Ultrasonic sensor 62 Ultrasonic sensor

Claims (2)

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;
The longest period of time that is the longest continuous detection time in a certain period of the continuous detection time when the gas flow rate detecting means continuously detects a gas flow rate of a predetermined flow rate or more is monitored, and the longest period of time in the previous fixed period is A leakage determination level setting means that multiplies a safety factor and further multiplies the ratio of the longest period of time in a certain period of time before the previous period and the longest period of time in the previous certain period to obtain a leakage determination level ,
A gas leak determination means for monitoring the longest time in a certain period this time, and if the longest time period exceeding the leak determination level occurs,
A gas leak detection device comprising: 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;
The longest period of time in the predetermined period is monitored, and the longest period of time in the previous fixed period is monitored among the continuous detection times when the gas flow rate detecting means continuously detects the gas flow rate falling within the predetermined range. A leakage judgment level setting means for multiplying a safety factor and multiplying the ratio of the longest period of time in a certain period before the previous period and the longest period of time in the previous certain period to obtain a leakage judgment level ,
A gas leak determination means for monitoring the longest time in a certain period this time, and if the longest time period exceeding the leak determination level occurs,
A gas leak detection device comprising:

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