JP2621124B2 - Gas leak detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leak detecting device for detecting a gas leak in a gas supply system in which a gas supply source and a combustor are connected by a gas supply pipe.

[0002]

2. Description of the Related Art Liquefied petroleum gas (hereinafter, referred to as "LP gas") used in general households and the like is provided in an LP gas container (cylinder).
Is reduced to a predetermined pressure by a pressure reducing valve (pressure regulator) and supplied to a combustor such as a gas stove via a gas supply pipe. Regarding gas leakage in a house in such a gas supply system, a gas detector provided in the house issues an alarm when detecting gas leaked from a combustor, rubber pipes, or the like, and the user detects the gas in the house. Measures such as closing the main gas valve are taken.

[0003] In such a gas supply system, particularly when supplying LP gas to an apartment house or the like, it is necessary to provide a passage around the apartment house and to bury the gas supply pipe in the ground. There are many. Such gas supply pipes buried underground are susceptible to cracks due to the load from the ground surface and corrosion, and therefore, not only in the house, but also in the gas supply pipe from the LP gas container to the house. It is necessary to detect gas leaks.

In detecting a gas leak in a gas supply pipe, another pressure regulator is provided in parallel with the pressure regulator, and a parent-child type pressure regulator is constituted by these two pressure regulators. The applicant of the present invention has proposed a device provided with a minute flow rate detector capable of detecting a minute flow rate (for example, 3 liters / hour) in a bypass passage connected to the outlet side of the apparatus. In such a parent-child type pressure regulator, the adjustment pressure of the child side pressure regulator is adjusted with respect to the adjustment pressure of the parent side pressure regulator.
For example, by setting the pressure to 20 mmH ₂ O (underwater pressure) high, when the gas consumption is large, such as during the daytime, the pressure of the gas supply pipe is low. When the amount used decreases, the pressure in the gas supply pipe increases, eventually approaching the pressure of the pressure regulator on the child side, the pressure regulator on the parent side is closed, and all the supplied gas passes through the micro flow rate detector. Become. Then, when the minute flow rate detector continuously detects a flow rate equal to or more than a predetermined amount continuously for, for example, 720 hours (30 days), it is presumed that there is a minute leak of gas, and the gas supplier is notified.

[0005]

However, in such a gas leak detection, when the minute flow rate detector judges that there is no flow rate, the time measurement of 720 hours is cleared halfway,
Due to the logic of starting time measurement when it is determined that there is a flow rate again, if the diameter of the gas supply pipe downstream of the minute flow rate detector is large or the piping distance is long, the LP gas in the gas supply pipe will The pressure may change under the influence of the outside air temperature, and the following erroneous determination may be made.

(1) Although a flow rate is actually generated, the gas pressure rises due to an increase in the outside air temperature, the flow rate does not appear in the micro flow rate detector, and it is erroneously determined that there is no flow rate, and the time is cleared. Would.

(2) Actually, no flow rate is generated, but the gas pressure decreases due to a decrease in the outside air temperature, the flow rate appears in the minute flow rate detector, and it is erroneously determined that there is a flow rate, and the time is not cleared.

Accordingly, an object of the present invention is to accurately detect gas leakage even when the outside air temperature changes.

[0009]

In order to achieve the above object, the present invention, as shown in the basic configuration diagram of FIG. 1, controls the flow rate of gas in a gas supply pipe for transferring gas from a gas supply source to a combustor. The flow rate detecting means 27 for detecting, the pressure change detecting means 29 for detecting a change in pressure on the downstream side of the flow rate detecting means 27, and the time during which the gas flow rate is detected by the flow rate detecting means 27 are continuously measured. A timer 37, and an alarm processing unit 31a that performs processing such as an alarm when the time measured by the timer 37 reaches a predetermined time, and a signal indicating whether or not there is a flow from the flow detecting unit 27; The presence or absence of a flow rate is determined based on a signal indicating the presence or absence of a pressure change from the pressure change detection unit 29, and when it is determined that there is no flow rate, the flow presence / absence determination unit 3 that resets the timing of the timer 37.
1b.

[0010]

According to such a gas leakage detecting device, the flow rate detecting means 27 detects the flow rate of the gas flowing in the gas supply pipe, and detects the pressure change of the gas downstream of the flow rate detecting means 27. 29 detects. The time during which the gas flow rate is detected by the flow rate detecting means 27 is
Are continuously measured, and when the time measured by the time measuring means 37 reaches a predetermined time, the alarm processing means 31a performs processing such as an alarm. The flow rate presence / absence determining means 31b determines the presence / absence of the flow rate based on the signal indicating the presence / absence of the flow rate from the flow rate detecting means 27 and the signal indicating the presence / absence of the pressure change from the pressure change detecting means 29, and determines that there is no flow rate. Then, the timer of the timer 37 is reset.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is an overall configuration diagram of the LP gas supply system. A gas cylinder 1 as a gas supply source and an apartment house (apartment) 3 are connected by a gas supply pipe 5. The gas supply pipe 5 has a buried portion 5a buried underground.
Exists, and the piping route is relatively long. Near the gas cylinder 1 side of the gas supply pipe 5, a first pressure regulator 7 and a second pressure regulator 9 are provided in order from the gas cylinder 1 side. The gas decompressed and adjusted by each of the pressure regulators 7 and 9 is introduced into the apartment house 3 through the valve 11, and the valve 13 and the meter 1 are provided for each household.
The gas is supplied to a combustor 17 such as a gas stove via a gas stove 5.

The second pressure regulator 9 is of a parent-child type similar to that described in the prior art, and includes a parent pressure regulator 9a for a large flow rate and a child pressure regulator 9b for a small flow rate. .
The parent pressure regulator 9a is provided in the middle of the gas supply pipe 5, while the child pressure regulator 9b is provided in the middle of a bypass pipe 19 that bypasses the parent pressure regulator 9a. A minute flow rate detection meter 21 for detecting a minute flow rate of gas (for example, 3 liters / hour) is interposed in the bypass pipe 19 on the downstream side of the child pressure regulator 9b. A valve 23 and a valve 25 are provided on the bypass pipe 19 on the downstream side of the minute flow rate detection meter 21 and on the upstream side of the child pressure regulator 9b, respectively.

The minute flow rate detection meter 21 has a built-in electronic circuit unit 22 and, as shown in the block diagram of FIG. 3, a flow rate sensor 27 as flow rate detection means for detecting rotation of the measuring section. A pressure sensor 29 serving as pressure detecting means for detecting the outlet pressure of the flow rate sensor 27, and a microprocessor C or the like configured to determine gas leakage based on the detection results of the sensors 27 and 29, for example.
PU31 and R for storing programs, fixed data, etc.
OM 33 and RAM 3 for storing flow rate information and pressure information detected by the sensors 27 and 29 and other temporary data.
5, a timer 37 which is built in the RAM 35 and measures, for example, 720 hours as a gas leak check period, and a communication circuit which communicates gas leak information to the management center by a communication line when the CPU 31 determines that there is gas leak. 41.

The CPU 31 has an alarm processing means 31a which outputs a signal to the communication circuit 41 to perform processing such as an alarm when the time counted by the timer 37 reaches a predetermined time (720 hours). A signal indicating the presence or absence of a flow rate (no flow rate below 12 liters / hour) and a signal indicating the presence or absence of a pressure change from the pressure sensor 29 (100 mmH ₂ O)
/ H, a change of less than / h) and the presence or absence of a flow rate is determined.
7 is provided with a flow rate presence / absence determining means 31b for resetting the time measurement.

As shown in the front view of FIG. 4, the minute flow rate detection meter 21 has an integrating display 43 composed of an integrating character wheel for integrating and displaying the gas flow rate, and displays an alarm when the CPU 31 determines that there is a gas leak. An alarm indicator 45 composed of an LED and a communication terminal 46 to which a communication control device 47 is connected.
And Information is transmitted from the communication control device 47 to the host computer 48 on the management center side via a communication line.

As shown in FIG. 5, the flow sensor 27 reciprocates the gas by alternately flowing gas into two spaces defined by a diaphragm (not shown). The disk 53 provided with the magnet 51 rotates, and the reed switch 55 provided facing the disk 53 detects the magnet 51 and emits a pulse signal to measure the gas flow rate.

Next, the control operation of the CPU 31 in the gas leakage determination device configured as described above will be described with reference to the flowchart shown in FIG. First, the flow sensor 27
And the gas pressure in the gas supply pipe 5 by the pressure sensor 29 are read (step S60).
1), the read gas flow rate is 12 l (liter) / h
(Time) or less (1 pulse 0.7 liter, 5 minutes 1
It is determined whether or not a pulse has not been transmitted (step S603). Here, the gas flow rate is 12 l / h
In the following cases, it is determined whether or not the change in the read pressure with respect to the pressure detected last time (about 10 minutes before) is less than 100 mmH ₂ O / h (step S605). If the pressure change is less than 100 mmH ₂ O / h, it is determined that the pressure change does not affect the detected flow rate, it is determined that there is no flow rate (step S607), and the timer 37 is cleared (step S6).
09), when it is 100 mmH ₂ O / h or more, it is determined whether or not the pressure change is in a descending state (step S61).
1). Here, when the pressure is falling, the detected flow rate is 1 despite the fact that the flow rate is larger than it actually appears due to the drop.
Since the flow rate is as small as 2 l / h or less, it is determined that there is no flow rate (step S607). Conversely, if the pressure is rising,
Since the detected flow rate becomes smaller than the actual flow rate due to the rise, the timer 37 is started (step S61).
5) It is determined whether or not the timer 37 has continuously counted time for 720 hours (step S617). If the time has been measured continuously for 720 hours, it is determined that a gas leak has occurred and the gas is abnormal (step S619). At the time of this abnormality, the alarm indicator 45 is turned on, and the control center is notified via the communication circuit 41 (step S620).
Is cleared (step S622).

In step S603, the gas flow rate is 12 l.
/ H, the gas pressure change is 100 m
It is determined whether it is less than mH2 O / h (step S61).
3). Here, when the pressure change is less than 100 mmH ₂ O / h, the processing after step S615 is performed. In step S613, the pressure change is 100 mmH _2.
When the gas flow rate is O / h or more, it is determined whether the gas flow rate is 20 l / h or more (step S621). I do.

In step S621, the gas flow rate is set to 20 l.
If it is less than / h, the process proceeds to step S611, and the same processing is performed thereafter.

FIG. 7 shows the result of the above control operation according to the gas flow rate detected by the flow rate sensor 27 and the gas pressure detected by the pressure sensor 29.

As described above, in the above embodiment, the flow rate detected by the flow rate sensor 27 in the minute flow rate
Even if the gas pressure is as low as 1 / h or less, the gas pressure is 100
When the pressure rises by not less than mmH ₂ O / h, it is determined that there is a flow rate because the increase in the flow rate is offset by the pressure rise, and there is a possibility that the gas actually leaks. Further, even if the flow rate detected by the flow rate sensor 27 is increased to more than 12 l / h and less than 20 l / h, if the gas pressure drops by 100 mmH ₂ O / h or more, the gas flow rate that has been detected largely becomes smaller than the gas pressure. Since it can be determined that the flow is caused by the descent, it is determined that there is no flow rate. As a result, even if the outside air temperature changes and the gas pressure in the gas supply pipe 5 greatly changes, gas leakage is accurately determined, and the reliability is high.

In the above embodiment, the gas supply system in an apartment house or the like has been described. However, the present invention is not limited to this, and each house is connected to each house via a gas supply pipe from an LP gas cylinder provided for each house. The present invention may be applied to a gas supply system,
Although the example of LP gas has been described, the present invention may be applied to city gas.

In the above embodiment, the flow rate is set to 12 l / h or less, but the detection time is extended to, for example, 3 l / h.
h or less may be regarded as no flow rate.

[0025]

As described above, according to the present invention, the determination of the gas leak in the gas supply pipe is performed not only by detecting the abnormal flow rate of the gas flowing through the gas supply pipe, but also by determining the pressure of the gas in the gas supply pipe. Since the change is detected and performed, even if the outside air temperature changes and the gas pressure in the gas supply pipe changes by a predetermined value or more, it is possible to prevent erroneous determination of gas leakage.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a gas leak detecting apparatus according to the present invention.

FIG. 2 is an overall configuration diagram of a gas supply system showing one embodiment of the present invention.

FIG. 3 is a block diagram showing a circuit configuration of a gas leakage detecting device in the gas supply system of FIG. 1;

FIG. 4 is a front view of a minute flow rate detection meter used in the gas supply system of FIG. 1;

FIG. 5 is an explanatory diagram of a flow sensor built in the minute flow detection meter of FIG. 3;

FIG. 6 is a flowchart showing a control operation of a CPU in the gas leakage detecting apparatus according to one embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a determination result based on a gas flow rate and a gas pressure change.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 LP gas cylinder (gas supply source) 9 pressure regulator 9 a parent pressure regulator 9 b child pressure regulator 5 gas supply pipe 17 combustor 27 flow sensor (flow detection means) 29 pressure sensor (pressure change detection means) 31 CPU (alarm) Processing means, flow rate determination means) 31a alarm processing means 31b flow rate determination means 37 timer (time measuring means)

Claims (2)

(57) [Claims] 1. A flow rate detecting means for detecting a flow rate of a gas in a gas supply pipe for transferring a gas from a gas supply source to a combustor, and a pressure change detecting means for detecting a change in pressure downstream of the flow rate detecting means. A time measuring means for continuously measuring the time during which the gas flow rate is detected by the flow rate detecting means; and an alarm processing means for performing an alarm or the like when the time measured by the time measuring means reaches a predetermined time. And, based on the signal of the presence or absence of the flow from the flow detection means, and the signal of the presence or absence of the pressure change from the pressure change detection means, to determine the presence or absence of the flow rate, when it is determined that there is no flow, An apparatus for detecting minute leakage of gas comprising a flow rate presence / absence determining means for resetting the time counting of the time counting means. 2. The flow rate presence / absence determination means determines that there is no flow rate when at least the flow rate detected by the flow rate detection means is equal to or less than a predetermined amount and the pressure change detected by the pressure change detection means is equal to or less than a predetermined amount. 2. The gas leakage detecting device according to claim 1, wherein: