JP7010708B2 - Gas meter - Google Patents

Description

The present invention relates to a gas meter through which flammable gas flows.

The gas supplier sends flammable gas to the consumer facility (customer facility) through piping. Then, at the consumer facility, the flow rate of the used combustible gas is detected through a gas meter. When the gas meter is installed or replaced, the gas flow path and piping in the gas meter are not filled with flammable gas, and air remains. If the predetermined conditions are met with the air remaining in this way, there is a risk of explosion or the like. Therefore, so-called air purging is performed to remove residual air other than combustible gas in the gas meter.

Further, there is known a technique of providing an opening / closing means for switching between a communication state and a cutoff state between a pipe and a gas meter, and exchanging the gas meter without performing an air purge (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-053071

As described above, air purge is performed when installing or replacing the gas meter. The gas discharged by the air purge is released to the atmosphere. If it is difficult to dissipate flammable gas to the atmosphere, a hose is connected to the inspection port and air purging is performed using a dedicated gas adsorbent. However, the capacity of the pipe to be air purged differs depending on the installation mode of the gas meter, and the capacity of the pipe also affects the execution time of the air purge. Therefore, in order to reliably complete the air purge regardless of the capacity of the pipe, it is necessary to set the execution time of the air purge sufficiently long.

In addition, even if the air purge is performed after spending a sufficiently long time, there is no way to directly judge whether or not the air is sufficiently discharged from the gas flow path and the pipe of the gas meter, and the operator has no way to directly judge whether or not the air is sufficiently discharged from the gas flow path and the pipe. I had to collect the gas and check the oxygen concentration. The work of confirming the oxygen concentration is highly dangerous and requires skill, which imposes a burden on the operator.

In addition, even if air is mixed in during normal gas supply for some reason, the membrane gas meter cannot detect it, while the ultrasonic gas meter can detect it, but the oxygen concentration is specified for detection. There was a problem that it required.

In view of such problems, it is an object of the present invention to provide a gas meter capable of easily and accurately detecting air contamination.

In order to solve the above problems, the gas meter of the present invention includes a gas flow path, a flow rate sensor that detects the flow rate of combustible gas flowing through the gas flow path, and an oxygen sensor that detects the oxygen concentration in the gas flow path. An inspection port mechanism that can close the inspection port that communicates between the gas flow path and the outside, and an inspection port control that causes the inspection port mechanism to close the inspection port when the oxygen concentration detected by the oxygen sensor falls below a predetermined first threshold value. It is equipped with a department .

When the oxygen concentration detected by the oxygen sensor becomes less than a predetermined first threshold value, a completion notification unit may be provided to notify the outside to that effect.

A shut-off valve that shuts off the supply of flammable gas, and a shut-off valve that shuts off the supply of flammable gas when the oxygen concentration detected by the oxygen sensor reaches a predetermined second threshold value or higher after the start of distribution of the flammable gas. A cutoff control unit may be provided.

The shutoff valve may be provided with a shutoff notification unit for notifying the outside that the supply of flammable gas has been shut off.

In order to solve the above problems, other gas meters of the present invention include a gas flow path, a flow rate sensor that detects the flow rate of combustible gas flowing through the gas flow path, and a nitrogen sensor that detects the nitrogen concentration in the gas flow path. An inspection port mechanism that can close the inspection port that connects the gas flow path and the outside, and an inspection that causes the inspection port mechanism to close the inspection port when the nitrogen concentration detected by the nitrogen sensor falls below a predetermined first threshold value. It is equipped with a mouth control unit .

According to the present invention, it is possible to detect air contamination easily and with high accuracy.

It is a figure which showed the schematic structure of the gas supply system. It is a functional block diagram which showed the schematic structure of a gas meter. It is a flowchart which showed the processing flow of the completion notification part. It is a flowchart which showed the processing flow of the inspection port control part. It is a flowchart which showed the processing flow of the cutoff control unit and the cutoff notification unit.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and the drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate explanations, and elements not directly related to the present invention are not shown. do.

(Gas supply system 100)
FIG. 1 is a diagram showing a schematic configuration of a gas supply system 100. In the gas supply system 100, as shown by the arrow in FIG. 1, the combustible gas is supplied from the combustible gas supply company (gas supply company) through the upstream pipe 110, and the flow rate of the combustible gas is measured by the gas meter 120. The combustible gas is delivered to the gas appliance 140 in the consumer facility 10 through the downstream pipe 130 connected to the downstream side of the gas meter 120 after detection. The downstream pipe 130 is provided with an inspection port (pressure sensing port) 130a that communicates with the outside atmosphere.

(Gas meter 120)
FIG. 2 is a functional block diagram showing a schematic configuration of the gas meter 120. The gas meter 120 includes a pressure sensor 150, a flow rate sensor 152, a shutoff valve 154, a display unit 156, an oxygen sensor 158, an inspection port mechanism 160, and a control unit 162. In FIG. 2, the broken line arrow and the white arrow indicate the flow of combustible gas, and the solid line arrow indicates the signal flow.

The pressure sensor 150 is provided on the downstream side of the shutoff valve 154 in the gas flow path 164 and detects the pressure of the flammable gas.

The flow sensor 152 is, for example, an ultrasonic flow sensor, and is composed of an ultrasonic vibrator 152a, an ultrasonic vibrator 152b, and a propagation velocity derivation unit 152c. The ultrasonic transducers 152a and 152b are arranged at predetermined positions on the upstream side surface and the downstream side surface of the gas flow path 164 on the downstream side of the shutoff valve 154 and the upstream side of the pressure sensor 150, for example, 20 kHz or more. It functions as a transmitter and receiver of ultrasonic waves, which are sound waves. The propagation velocity derivation unit 152c detects the propagation time of the ultrasonic wave propagating between the ultrasonic vibrators 152a and 152b via the combustible gas, and derives (detects) the flow rate of the combustible gas based on the propagation time. The flow rate sensor 152 is not limited to the ultrasonic type, but has various measurement principles such as, for example, a membrane type flow rate sensor that alternately fills and discharges flammable gas into a plurality of measuring chambers partitioned by a movable membrane. Sensors can be used.

The shutoff valve 154 is composed of a solenoid valve or an electromagnetic valve using a stepping motor, and controls the supply of flammable gas by switching the gas flow path 164 to a valve open state or a valve closed state. For example, when the pressure sensor 150 detects an abnormal value of the pressure of the flammable gas, or the flow rate sensor 152 detects that the flammable gas is continuously flowing at a predetermined flow rate or more for a predetermined period, the flow sensor 152 thereof is detected. Based on the detection signal, the shutoff valve 154 is switched from the valve open state to the valve closed state, and the flammable gas is shut off.

The display unit 156 is composed of a liquid crystal display, an organic EL (Electro Luminescence) display, etc., and is used to notify an integrated value of the supply amount (usage amount) of the combustible gas and an abnormality such as leakage of the combustible gas. ..

The oxygen sensor 158 is provided in the gas flow path 164 and detects the concentration of oxygen in the gas atmosphere existing in the gas flow path 164. With the oxygen sensor 158, it is easy and highly accurate whether or not air containing oxygen is mixed in the gas (flammable gas) in the gas flow path 164 and how much air is mixed. Can be detected. As the oxygen sensor 158, an inexpensive and compact galvanic cell type is adopted. However, as the oxygen sensor 158, not only a galvanic cell type but also a zirconia type, a limit current type, a magnetic type, and various other measurement principles can be adopted.

Here, the galvanic cell-type oxygen sensor uses two types of metals (noble metal and base metal) with different ionization tendencies, and consists of a pair of electrodes consisting of a cathode of the noble metal (gold, etc.) and an anode of the base metal (lead). , The oxygen concentration is obtained based on the current proportional to the amount of oxygen flowing by connecting the anode and cathode electrodes. In addition, the zirconia type oxygen sensor is provided with porous electrodes on both sides of the zirconia ceramics, and keeps the zirconia at a high temperature to have ionic conductivity, and oxygen ions from the side with high oxygen concentration to the side with low oxygen concentration. Measure the electromotive force based on the movement of. In the limit current type oxygen sensor, when the sensor element of the zirconia solid electrolyte is charged, an ion current with oxygen ions as a carrier flows, and when the amount of oxygen diffusion on the inflow side of the sensor is limited by the porosity, the oxygen diffusion in the porosity Using the principle of being limited by a current value proportional to the amount, the oxygen concentration is obtained based on this current value. The magnetic oxygen sensor utilizes the property that oxygen is a paramagnetic substance having a large magnetic susceptibility unlike other molecules, and measures the attractive force generated when magnetized in a magnetic field to obtain the oxygen concentration.

The inspection port mechanism 160 is composed of a solenoid valve or a solenoid valve using a stepping motor, and can switch the inspection port 130a provided in the downstream pipe 130 from the open state to the closed state.

The control unit 162 manages and controls the entire gas meter 120 by a semiconductor integrated circuit including a central processing unit (CPU), a PROM in which a program or the like is stored, a RAM as a work area, and the like. Further, the control unit 162 functions as a completion notification unit 170, an inspection port control unit 172, a cutoff control unit 174, and a cutoff notification unit 176 in cooperation with the program. The operation of such a functional unit (completion notification unit 170, inspection port control unit 172, cutoff control unit 174, cutoff notification unit 176) will be described in detail later.

(Air purge)
When the gas meter 120 is installed or replaced, the gas flow path 164 in the gas meter 120 and the downstream pipe 130 are not filled with flammable gas, and air remains. If the predetermined conditions are met with the air remaining in this way, there is a risk of explosion or the like. Therefore, an air purge is performed to remove residual air other than the combustible gas in the gas meter 120.

As the air purge, for example, it is conceivable that the gas appliance 140 of the consumer facility 10 is used and the operator removes the residual air through the gas appliance 140. It is also conceivable to dissipate residual air and flammable gas to the atmosphere through the inspection port 130a. When it is difficult to use the gas appliance 140 or to dissipate flammable gas to the atmosphere, a hose is connected to the inspection port 130a and air purging is performed using a dedicated gas adsorbent. However, the capacity of the downstream pipe 130 to be air purged differs depending on the installation mode of the gas meter 120, and the capacity of the downstream pipe 130 also affects the execution time of the air purge. Therefore, in order to reliably complete the air purge regardless of the capacity of the downstream pipe 130, it is necessary to set the execution time of the air purge sufficiently long.

Further, even if the air purge is performed after spending a sufficiently long time, there is no way for the operator to directly determine whether or not the air is sufficiently discharged from the gas flow path 164 of the gas meter 120 and the downstream pipe 130, and the operator performs the air purge. It was necessary to collect the gas in the later downstream pipe 130 and confirm that the oxygen concentration was below a predetermined value. The work of confirming the oxygen concentration is highly dangerous and requires skill, which imposes a burden on the operator. Therefore, in the present embodiment, air contamination is detected easily and with high accuracy, and various processes are safely and efficiently performed based on the detection results.

(Completion notification unit 170)
FIG. 3 is a flowchart showing the processing flow of the completion notification unit 170. First, the completion notification unit 170 determines whether or not the air purge start work has been performed after the installation or replacement of the gas meter 120 (S1), and the determination process until the air purge start work is performed (NO in S1). repeat. For example, the completion notification unit 170 has detected an air purge start operation by an operator, the pressure sensor 150 has detected a value of a predetermined pressure or more by the air purge start operation, the flow rate sensor 152 has detected a flow rate of a predetermined flow rate or more, or It is determined that the air purge start work has been performed based on the air purge start command or the like transmitted from the outside through communication.

Then, when it is determined that the start operation of the air purge has been performed (YES in S1), the completion notification unit 170 causes the oxygen sensor 158 to detect the oxygen concentration (S2).

Next, the completion notification unit 170 compares the oxygen concentration detected by the oxygen sensor 158 with a predetermined first threshold value that can be regarded as the completion of the air purge, and the oxygen concentration is less than the first threshold value. Whether or not it is determined (S3), and the comparison process is repeated until the value becomes less than the first threshold value (NO in S3).

Then, when the oxygen concentration becomes less than the first threshold value (YES in S3), the completion notification unit 170 notifies the outside through, for example, the display unit 156 that the air purge has been completed (S4). The notification is not limited to the display unit 156, and includes, for example, transmitting to the center device through communication and notifying the consumer of the content thereof. Further, such a notification may be deleted at a predetermined timing such as the passage of a certain amount of time or a day span.

The operator grasps that the air purge has been completed through the display unit 156, and closes the inspection port 130a. Here, since the oxygen concentration of the downstream pipe 130 is directly detected, it is possible to grasp the mixing of air with high accuracy. In this way, regardless of the capacity of the downstream pipe 130, it is possible to efficiently complete the air purge at an appropriate timing when the air is removed. Therefore, the working time of air purging can be shortened.

In addition, the fact that the completion notification of the air purge has been given indicates that air has not already been mixed in the downstream side pipe 130, so that it is not necessary to measure the oxygen concentration in the downstream side pipe 130 after the fact, and the work is performed. It is possible to reduce the burden on the person and ensure safety with simple work.

(Inspection port control unit 172)
However, if the display unit 156 is notified that the air purge is completed and the operator grasps it and closes the inspection port 130a, a delay of the working time may occur. Therefore, the inspection port mechanism 160 is provided in the inspection port 130a, and the inspection port 130a is automatically closed through the inspection port control unit 172.

FIG. 4 is a flowchart showing the processing flow of the inspection port control unit 172. First, the inspection port control unit 172 determines whether or not the air purge start work has been performed after the gas meter 120 has been installed or replaced (S11), and the determination is made until the air purge start work is performed (NO in S11). Repeat the process.

Then, when it is determined that the air purge start operation has been performed (YES in S11), the inspection port control unit 172 causes the oxygen sensor 158 to detect the oxygen concentration (S12).

Next, the inspection port control unit 172 compares the oxygen concentration detected by the oxygen sensor 158 with a predetermined first threshold value that can be regarded as the completion of the air purge, and the oxygen concentration is less than the first threshold value. It is determined whether or not there is (S13), and the comparison process is repeated until the value becomes less than the first threshold value (NO in S13).

Then, when the oxygen concentration becomes less than the first threshold value (YES in S13), the inspection port control unit 172 closes the inspection port 130a through the inspection port mechanism 160 (S14). The inspection port mechanism 160 may be configured to be openable and closable according to a control signal, but it is sufficient if the opening can be closed, the opening may be manually performed, and only the closing may be automatically performed according to the control signal.

Here, since the oxygen concentration of the downstream pipe 130 is directly detected, it is possible to grasp the mixing of air with high accuracy. In this way, regardless of the capacity of the downstream pipe 130, it is possible to reliably complete the air purge at an appropriate timing when the air is removed. Further, since the inspection port 130a is automatically closed when the oxygen concentration becomes less than the first threshold value, the working time of air purging can be further shortened.

Further, closing the inspection port 130a indicates that air has not already been mixed in the downstream side pipe 130, so that it is not necessary to measure the oxygen concentration in the downstream side pipe 130 after the fact, and the operator It is possible to reduce the burden on the air and ensure safety with simple work.

In the process of closing the inspection port 130a (S14), the completion notification unit 170 notifies the outside that the air purge has been completed, for example, through the display unit 156, in order to make the operator know that the air purge has been completed. May be.

Further, here, an example in which the inspection port mechanism 160 is provided in advance in the inspection port 130a is given, but only when the gas meter 120 is installed or replaced, that is, when the air purge is executed, the inspection port 130a is provided with the inspection port 130a. The mechanism 160 may be installed.

(Cut off control unit 174, cutoff notification unit 176)
As described above, when the air purge is completed after the gas meter 120 is installed or replaced, the combustible gas is started (resumed) to be distributed, and the consumer can use the gas appliance 140. However, in the normal supply of flammable gas, air may be mixed in for some reason. In this case, the membrane gas meter cannot detect it. Further, although the ultrasonic gas meter can detect itself, it requires a predetermined oxygen concentration for detection. Therefore, in the present embodiment, the oxygen concentration detected by the oxygen sensor 158 is used to detect air contamination even in a normal state.

FIG. 5 is a flowchart showing the processing flow of the cutoff control unit 174 and the cutoff notification unit 176. First, the cutoff control unit 174 determines whether or not the work of starting (resuming) the distribution of the flammable gas has been performed after the completion of the air purge (S21), and until the work of starting the distribution is performed (NO in S21). The determination process is repeated. For example, the cutoff control unit 174 has detected a distribution start operation by an operator, the pressure sensor 150 has detected a value of a predetermined pressure or more by the distribution start operation, the flow sensor 152 has detected a flow rate of a predetermined flow rate or more, or It is determined that the work to start the distribution of combustible gas has been performed based on the distribution start command etc. transmitted from the outside through communication.

Then, when it is determined that the work of starting distribution has been performed (YES in S21), the cutoff control unit 174 causes the oxygen sensor 158 to detect the oxygen concentration (S22).

Next, the cutoff control unit 174 compares the oxygen concentration detected by the oxygen sensor 158 with a predetermined second threshold value that can be regarded as a dangerous state due to air contamination, and the oxygen concentration is determined. It is determined whether or not it is equal to or higher than the second threshold value (S23), and the comparison process is repeated until it becomes equal to or higher than the second threshold value (NO in S23).

Then, when the oxygen concentration becomes equal to or higher than the second threshold value (YES in S23), the shutoff control unit 174 shuts off the supply of the flammable gas through the shutoff valve 154 (S24).

Further, the shutoff notification unit 176 notifies the outside that the shutoff valve 154 has shut off the supply of the flammable gas (S25).

In this way, even after the distribution of combustible gas is started, it is possible to easily and accurately detect the inclusion of air and shut off the supply of flammable gas through the existing shutoff valve 154, so that safety is possible. Can be secured.

Further, since air is often mixed in due to a disaster such as an earthquake, the function of the cutoff control unit 174 can be substituted for a seismic sensor that detects an earthquake. Therefore, it is possible to ensure safety without installing a new seismograph. By providing both the function of the cutoff control unit 174 and the seismic sensor, it is possible to detect a dangerous state even if one of them fails, and it is possible to improve safety.

Further, since the shutoff notification unit 176 notifies to that effect, the operator can quickly grasp the reason why the shutoff valve 154 is closed.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood.

For example, in the above-described embodiment, in order to confirm the oxygen concentration of the gas in the pipe after air purging, the oxygen concentration is detected by the oxygen sensor 158, and it is determined whether or not the oxygen concentration is less than the first threshold value. It was explained with an example. However, not limited to this case, instead of or in addition to the oxygen concentration, the nitrogen concentration is detected by a nitrogen sensor, it is determined whether or not the nitrogen concentration is less than a predetermined threshold value, and the nitrogen concentration is a predetermined threshold value. If it is less than, it may be considered that the air purge is completed. As the nitrogen sensor, existing techniques such as a sensor that derives the nitrogen concentration according to the heat conduction of the target gas and the temperature can be applied.

Further, in the above-described embodiment, the control unit 162 cooperates with the program to function as a completion notification unit 170, an inspection port control unit 172, a cutoff control unit 174, and a cutoff notification unit 176. However, these functional units are not always provided in the gas meter 120, but may be provided in an external device and may realize the operation of the present embodiment by communicating with the gas meter 120.

Further, in the above-described embodiment, the first threshold value and the second threshold value are expressed as different values, but the same value may be used.

It should be noted that each process executed by the completion notification unit 170, the inspection port control unit 172, the cutoff control unit 174, and the cutoff notification unit 176 of the present specification does not necessarily have to be processed in chronological order in the order described in the flowchart. Instead, it may include processing in parallel or by a subroutine.

The present invention can be used for a gas meter through which flammable gas flows.

130a Inspection port 152 Flow sensor 154 Shutoff valve 156 Display unit 158 Oxygen sensor 160 Inspection port mechanism 164 Gas flow path 170 Completion notification unit 172 Inspection port control unit 174 Shutdown control unit 176 Shutdown notification unit

Claims (5)

Gas flow path and
A flow rate sensor that detects the flow rate of combustible gas flowing through the gas flow path, and
An oxygen sensor that detects the oxygen concentration in the gas flow path and
An inspection port mechanism that can close the inspection port that communicates the gas flow path with the outside,
When the oxygen concentration detected by the oxygen sensor becomes less than a predetermined first threshold value, the inspection port control unit that causes the inspection port mechanism to close the inspection port,
A gas meter equipped with. The gas meter according to claim 1, further comprising a completion notification unit for notifying the outside when the oxygen concentration detected by the oxygen sensor is less than a predetermined first threshold value. A shutoff valve that shuts off the supply of the flammable gas,
After the work of starting the distribution of the combustible gas, when the oxygen concentration detected by the oxygen sensor becomes equal to or higher than a predetermined second threshold value, the shutoff control unit for causing the shutoff valve to shut off the supply of the flammable gas.
The gas meter according to claim 1 or 2 . The gas meter according to claim 3 , further comprising a shutoff notification unit for notifying the outside that the shutoff valve has shut off the supply of the flammable gas. Gas flow path and
A flow rate sensor that detects the flow rate of combustible gas flowing through the gas flow path, and
A nitrogen sensor that detects the nitrogen concentration in the gas flow path and
An inspection port mechanism that can close the inspection port that communicates the gas flow path with the outside,
When the nitrogen concentration detected by the nitrogen sensor becomes less than a predetermined first threshold value, the inspection port control unit that causes the inspection port mechanism to close the inspection port, and the inspection port control unit.
A gas meter equipped with.

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