JP3783831B2 - Flow rate measuring method, flow rate measuring apparatus, and gas meter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flow rate measuring method, a flow rate measuring device, and a gas meter.
[0002]
[Prior art]
In a conventional flow rate measurement method or flow rate measurement device in which ultrasonic waves are propagated in a fluid such as flammable gas and the flow velocity or flow rate of the fluid is measured, a distance is separated in the direction of flow in a conducting tube through which the fluid is conducted. Then, an ultrasonic generator / receiver is installed before and after the ultrasonic wave is propagated from the upstream side to the downstream side in the same direction (forward direction) as the fluid flow, and the propagation time is measured. When the propagation of sound waves is detected on the downstream side, the operation of propagating the ultrasonic waves from the downstream side to the upstream side in the opposite direction to the fluid flow and measuring the propagation time is repeated in both directions. The flow rate or flow rate of the fluid was measured based on the difference in the propagation time of the fluid.
[0003]
More specifically, in a flow rate measuring device such as a so-called ultrasonic propagation type gas meter, first, the propagation time of ultrasonic waves from the upstream side to the downstream side (referred to as T1) and the ultrasonic waves from the downstream side to the upstream side. , And the propagation time of this (referred to as T2) is measured. Here, since the propagation path of ultrasonic waves is generally provided so as to be oblique to the center line of the conducting tube, the oblique angle is θ, the distance that the ultrasonic wave propagates in the tube is L, If the sound speed of C is C, then T1 = L / (C + vcos θ) and T2 = L / (C−vcos θ). From these T1 and T2, the flow velocity value v can be obtained by the following equation: v = (L / 2 cos θ) · (1 / T1-1 / T2). The flow rate value Q is obtained by multiplying the flow velocity value v by the area S of the conducting tube.
[0004]
[Problems to be solved by the invention]
By the way, when air is mixed into the gas due to the construction of the conduit on the upstream side, the conventional gas meter cannot detect the flow of such different gases. For this reason, in an ultrasonic wave propagation type gas meter or the like, when a gas containing a large amount of air passes through the gas meter, there is a problem that a large error may occur in the flow rate measurement value. Further, in the gas combustion device on the downstream side, there is a problem that combustion disappears or incomplete combustion occurs.
[0005]
In addition, for example, in a flow measurement device for a chemical plant that handles a plurality of types of gases and liquids, when a fluid of a type different from a preset type of fluid flows due to some factor, It cannot be detected. In addition, when a fluid of a type different from the predetermined setting is flowing, even if an abnormal situation requiring some interruption or alarm occurs, the detection condition is different, so the detection device built in the flow measurement device There is a problem that it cannot be detected by a safety device or the like. In addition, if a fluid of a type different from the setting is supplied further downstream through the flow rate measuring device, the combustion process or chemical reaction process on the downstream side may cause incomplete combustion, overcombustion, or error. There is a problem that various inconveniences such as chemical reactions occur.
[0006]
Moreover, in order to solve the various problems as described above, it is conceivable to attach a sensor for discriminating the type or composition of the fluid, a type discriminating device for discriminating the type of fluid detected by the sensor, or the like. However, attaching them to the flow rate measuring device causes a complication of the entire device, and there is a problem that the cost for that is expensive.
[0007]
In particular, in recent gas meters, in order to continue accurate measurement with a built-in battery for many years, it is required to reduce the power consumption in the gas meter as much as possible. However, in order to solve the various problems as described above, in addition to the existing measuring device, if a sensor for discriminating the type and composition of the gas is further provided, it is continuously driven for many years. Therefore, there is a problem in that the amount of power consumption for increasing the power consumption further increases, preventing the reduction in power consumption, or going against it.
[0008]
The present invention has been made in view of such problems, and its purpose is that a fluid different from a predetermined fluid type and composition has flowed without causing the device to become complicated and increase the power consumption. It is an object of the present invention to provide a flow rate measuring method, a flow rate measuring device, and a gas meter that can detect the situation in case.
[0009]
[Means for Solving the Problems]
The flow rate measuring method according to the present invention includes a forward propagation time when a sound wave is propagated from the upstream side to the downstream side with respect to a fluid to be measured and a reverse direction when the sound wave is propagated from the downstream side to the upstream side. In the flow measurement method for measuring the propagation time and obtaining the flow value of the fluid based on the propagation time, Obtained by storing and measuring the distribution of a combination of a forward propagation time and a backward propagation time measured over a predetermined learning period in correspondence with a predetermined fluid type. A combination of a forward propagation time and a backward propagation time as a set, Memorized distribution of combinations Compared to Distribution of combinations A determination process for determining whether or not the vehicle deviates from the above is provided.
[0010]
In addition, the flow rate measuring method according to the present invention is such that when it is determined that the combination of the forward propagation time and the backward propagation time deviates from the predetermined combination, the fluid to be measured is a predetermined fluid. An alarm process may be further provided that generates an alarm indicating that the fluid is of a different type from at least one of audio information and visual information.
[0011]
In addition, the flow rate measuring method according to the present invention, when it is determined that the combination of the forward propagation time and the backward propagation time as one set deviates from the predetermined combination, the flow of the fluid to be measured is determined. You may make it further provide the interruption | blocking process to interrupt | block.
[0013]
Further, the flow rate measurement method according to the present invention sets an initial value of the distribution of the combination of the forward propagation time and the backward propagation time in advance, and the combination of the propagation times measured during the learning period starts from the initial value. In the case of deviation, the storage of the distribution may be reset and the storage of the combination distribution may be restarted.
[0014]
In addition, the flow rate measuring method according to the present invention provides a forward propagation time and a backward propagation time until a predetermined time elapses after the flow resumes after the fluid flow is stopped. Even if it is determined that the combination of the two sets deviates from the predetermined combination, the flow of the fluid to be measured may not be blocked.
[0015]
The flow rate measuring device according to the present invention has a forward propagation time when a sound wave is propagated from the upstream side to the downstream side with respect to the fluid to be measured, and a reverse direction when the sound wave is propagated from the downstream side to the upstream side. In a flow rate measuring device having an ultrasonic propagation time measuring means for measuring a propagation time and a flow rate value calculating means obtained by calculating a fluid flow value based on the propagation time, Obtained by storing and measuring the distribution of a combination of a forward propagation time and a backward propagation time measured over a predetermined learning period in correspondence with a predetermined fluid type. A combination of a forward propagation time and a backward propagation time as a set, Memorized distribution of combinations Compared to Distribution of combinations The determination means which determines whether it deviates from is provided.
[0016]
In addition, the flow rate measuring device according to the present invention enables the fluid to be measured to be a predetermined fluid when it is determined that the combination of the forward propagation time and the backward propagation time as a set deviates from the predetermined combination. You may make it further provide the alarm means which issues the alarm to the effect that it is a thing different from a fluid by at least any one of auditory information and visual information.
[0017]
The flow rate measuring device according to the present invention further includes a shut-off valve that shuts off a fluid flow, and a shut-off valve control unit that controls opening and closing operations of the shut-off valve, and sets a forward propagation time and a reverse propagation time as a set. When the determination means determines that the combination to be deviated from the predetermined combination, based on the determination, the shutoff valve control means controls the operation of the shutoff valve so as to shut off the flow of the fluid to be measured. It may be.
[0019]
Further, in the flow rate measuring device according to the present invention, the learning control means is preset with an initial value of the distribution of combinations, and when the combination of propagation times measured during the learning period deviates from the initial value, The storage of the distribution stored so far may be reset and the storage of the distribution of the combination may be restarted.
[0020]
In addition, the flow rate measuring device according to the present invention is configured so that the forward valve propagation means and the backward propagation time are not increased until a predetermined time elapses after the flow resumes after the fluid flow is stopped. Even if it is determined by the determination means that the combination of time and the set deviates from the predetermined combination, the flow of the fluid to be measured may not be blocked.
[0021]
A gas meter according to the present invention uses a flow rate measuring device in which the fluid is a gas.
[0022]
In the flow measurement method, the flow measurement device, and the gas meter according to the present invention, Obtained by storing and measuring the distribution of a combination of a forward propagation time and a backward propagation time measured over a predetermined learning period in correspondence with a predetermined fluid type. A combination of a forward propagation time and a backward propagation time as a set, Memorized distribution of combinations Compared to Distribution of combinations It is determined whether or not it deviates from the above. If it deviates, it is determined that the type or composition of the fluid flowing at that time is different from the predetermined fluid type.
[0023]
That is, based on the propagation time data measured by an existing general device for obtaining a flow rate measurement value, it is determined whether or not the fluid type or composition deviates from a predetermined value.
[0024]
When it is detected that fluids of different types or compositions have flowed, an alarm to that effect is generated or the supply of fluid is shut off (stopped) by a shut-off valve.
[0025]
In addition, by storing a distribution of combinations of a forward propagation time and a reverse propagation time that are actually measured over a predetermined learning period, the flow measurement device can be used in actual use. The learning value is automatically learned in a learning control manner with a normal value of the propagation time of a predetermined combination. Then, by comparing a predetermined combination obtained by the learning with a combination of propagation times measured thereafter, it is determined whether or not the type or composition of the flowing fluid deviates from the predetermined one. . As a result, the predetermined combination, which is a reference value for determining the type of fluid, can be made more finely and actually compliant than the case of presetting based on the theoretical value or the like. In addition, it is possible to make a more accurate determination based on the actual situation.
[0026]
However, here, when a situation occurs in which the type or composition of the fluid flowing during the learning period deviates from a predetermined value, the combination of propagation times at that time is learned (stored). In some cases, the accuracy of the predetermined combination as a normal value serving as a determination criterion may be impaired. Therefore, in such a case, the distribution data of the propagation time combinations stored so far is reset, and then the distribution of the propagation time combinations measured over the predetermined learning period is stored again. You can do that.
[0027]
Also, in the gas meter, for example, when the pipe work is performed on the upstream side, it is notified to the downstream consumers in advance, the use of the gas is temporarily stopped, and the use of the gas is resumed after the pipe work is completed. In such a case, as a so-called air vent, a gas mixed with a large amount of air downstream from the gas meter is discharged for a while. However, in such a case, if the gas meter detects the flow of gas containing a large amount of air and shuts off the valve, it may not be possible to vent the air. Therefore, in order to avoid such inconvenience, even if it is determined that the combination of the measured propagation times deviates from the predetermined combination from the gas stop state until the air venting is sufficiently completed, the measurement target It is sufficient not to block the flow of fluid.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0029]
FIG. 1 is a block diagram schematically showing a schematic configuration of a gas meter according to an embodiment of the present invention. In addition, since the flow measuring method in the gas meter which concerns on one embodiment of this invention is embodied by the gas meter which concerns on this Embodiment, it shall also be demonstrated collectively below.
[0030]
This gas meter includes an ultrasonic propagation time measuring unit (ultrasonic propagation time measuring unit) 100, a flow rate value calculating unit (flow rate value calculating unit) 200, a flow rate value integrating unit 300, a determining unit (determining unit) 400, An alarm unit (alarm unit) 500, a shut-off valve 600, and a shut-off valve control unit (shut-off valve control unit) 700 constitute the main part. In addition to this, it goes without saying that various devices that are generally used as a gas meter, such as a return switch for performing shut-off return and a micro-leakage detection device (all not shown), are included. These various devices and the like are not directly related to the main configuration of the present invention, and thus the description thereof is omitted.
[0031]
More specifically, the ultrasonic propagation time measurement unit 100 includes ultrasonic transmission / reception devices 101a and 101b, a propagation time measurement unit 102, and a conduction path 103. The ultrasonic transmission / reception devices 101a and 101b propagate the ultrasonic wave from the upstream side to the downstream side at a predetermined frequency per measurement duty for the gas to be measured flowing through the conduction path 103, and downstream. Propagating from the side to the upstream side is repeated alternately at a predetermined timing. The propagation time measuring unit 102 is based on the electrical signals output from the ultrasonic transmission / reception devices 101a and 101b, and the forward propagation time T1 when the sound wave is propagated from the upstream side to the downstream side and the upstream side from the downstream side. The backward propagation time T2 when the sound wave is propagated to the side is measured. It should be noted that the conductive path 103, the ultrasonic transmission / reception devices 101a and 101b, the hardware of the propagation time measurement unit 102, the control logic thereof, and the like may be the same as those of a conventional general one.
[0032]
Each time the ultrasonic propagation time measuring unit 100 measures the propagation times T1 and T2, the flow rate value calculating unit 200 obtains the flow velocity value v at that time based on the propagation times T1 and T2, and further determines the flow velocity value v. The flow rate coefficient k corresponding to the value v is obtained and an operation of multiplying them is performed to obtain the instantaneous gas flow rate value Q at the measurement duty at that time. As for the flow rate value calculation unit 200, conventional hardware may be used as its hardware and its control logic.
[0033]
The flow value integration unit 300 integrates the flow rate measurement value Q obtained by the flow value calculation unit 200. That is, when the flow rate value calculation unit 200 newly calculates the flow rate measurement value Q and the data is transmitted, the flow rate value integration unit 300 stores the data of the new flow rate measurement value Q until then. Is added to the integrated flow rate value ΣQ. In this way, when a new flow rate measurement value Q is transmitted, the flow rate integration unit 300 sequentially increments the flow rate integration value ΣQ.
[0034]
The determination unit 400 includes a comparison unit 410, a learning control unit 420, and a storage unit 430. In this determination unit 400, a set of propagation times T1 and T2 measured by the ultrasonic propagation time measuring unit 100 is used as a set of propagation times T1 set in advance corresponding to the type of gas or its composition component. , T2 to determine whether or not air is mixed in the flowing gas.
[0035]
The comparison unit 410 compares the measured combination of propagation times T1 and T2 with a predetermined combination, and if it deviates from that, it determines that the gas at that time is mixed with air. is there.
[0036]
For example, as shown in FIG. 2, the measured values of the propagation times T1 and T2 are expressed as (T1, T2) in coordinates with the forward propagation time T1 on the vertical axis and the reverse propagation time T2 on the horizontal axis. Assuming that one point of the combination is shown, the determination unit 400, when the one-point plot of the measurement result (T1, T2) is included in the predetermined region Gn indicated by hatching, At this time, it is determined that the gas to be measured is a genuine 13A gas having such a high purity that the mixed amount of air can be substantially ignored. Alternatively, when the measurement result is included in the region A deviating from the predetermined region Gn, the gas to be measured at this time is substantially incompletely burned in the gas as pure fuel. It is determined that a large amount of air that may cause inconveniences is mixed.
[0037]
The predetermined region Gn may be set in advance from the design point of the gas meter as a distribution region of a combination of (T1, T2) as shown in FIG. 2 as an example. Then, as will be described later, the learning control unit 420 learns the propagation time (T1, T2) measured under the condition where the normal gas is actually flowing over a predetermined learning period. As a result, the constant region Gn, which is a predetermined combination of (T1, T2) serving as a determination criterion, can be set more finely as being in accordance with actual use conditions for each individual gas meter.
[0038]
The learning control unit 420 stores, in the storage unit 430, a distribution of combinations in which the forward propagation time T1 and the backward propagation time T2 that are measured over a predetermined learning period such as a half year or one year are set. By doing (storing), the distribution of the predetermined combination, that is, the data of the predetermined region Gn is learned according to the actual use condition of the gas meter. Further, the learning control unit 420 has an initial value of the distribution of the predetermined combination set in advance from the time of shipment of the gas meter, and the combination of propagation times measured during the predetermined learning period deviates from the initial value. If this happens, the data learned so far and stored in the storage unit 430 is reset, and the distribution of the combination is learned again over a predetermined period, and the new learning is performed. The obtained data is stored in the storage unit 430.
[0039]
The storage unit 430 stores data of initial values of a predetermined combination distribution and data of a predetermined combination distribution obtained by learning by the learning control unit 420. As the storage unit 430, for example, a storage element capable of writing / reading data such as a RAM or an EEPROM can be preferably used.
[0040]
If the determination unit 400 determines that the combination of the forward propagation time T1 and the reverse propagation time T2 as a set deviates from the predetermined combination, the alarm unit 500 may cause some cracks in the gas piping path or the like. Therefore, a warning that air is mixed in the measurement target gas is generated by the sound of the electronic alarm 510 and the light emission of the LED 520 based on the determination.
[0041]
The shut-off valve 600 includes a valve mechanism such as an electromagnetic valve, and shuts off / opens the gas flow by opening and closing the valve.
[0042]
The shut-off valve control unit 700 controls the opening / closing operation of the shut-off valve 600. More specifically, the shutoff valve 600 is controlled so as to perform the valve closing operation when a seismic sensor (not shown) detects that a so-called shutoff event such as inner pipe leakage or earthquake detection has occurred. Needless to say, in addition to this, when the determination unit 400 determines that a large amount of air is mixed in the gas, there is a possibility that some cracks or leaks have occurred in the gas piping path or the like. Therefore, the shutoff valve 600 is controlled so as to perform the valve closing operation based on the determination. However, when the flow is resumed after the gas is stopped, a large amount of air is taken in the meantime in order to allow so-called air venting for a predetermined time from the resumption point. Even if the determination unit 400 determines that air is mixed, the shutoff valve 600 does not execute shutoff. As such a predetermined time, it is preferable to set the time so that the air can be removed sufficiently and sufficiently.
[0043]
Needless to say, the return operation of the shut-off valve 600 is not only electrically executed by the shut-off valve control unit 700 but also executed by operating a general return switch (not shown). Yes.
[0044]
Next, an experimental result confirming that it is possible to determine whether or not a large amount of air is mixed in the gas at that time based on the combination of the measured propagation times T1 and T2 as one set. And the theoretical analysis is described.
[0045]
FIG. 3 is a diagram showing an experimental result obtained by examining what distribution a combination of T1 and T2 of the measurement result shows in the case of 13A gas and air. In FIG. 3, the vertical axis represents the forward propagation time T1 and the horizontal axis represents the backward propagation time T2 in units of [μs]. In addition, the number of times of measurement in one flow rate state is 100 to 500 times, and these are all plotted in FIG. The specifications of such a graph are the same as in FIGS.
[0046]
From the experimental results shown in FIG. 3, the distribution of the plots of the propagation times for the high-purity 13A gas and the air is divided into two regions that are clearly separated from each other. Was confirmed. In addition, it was confirmed that the region G and the region A remained clearly separated even when the flow rates of gas and air were variously changed or when pulsation occurred in the gas flow.
[0047]
Furthermore, the distribution region of the plot of the propagation time (T1, T2) measured when air is mixed in the 13A gas (this is called G / A. The same applies hereinafter) is as shown in FIG. It was found that it was distributed in any band between the distribution region G in the case of high purity 13A gas and the distribution region A in the case of air.
[0048]
More specifically, the flow rate is 25 [L / h (liters / hour; the same applies hereinafter)], 40 [L / h], 200 [L / h], 400 [L / h] with 13A gas as a measurement target. , 600 [L / h], 1900 [L / h], 3800 [L / h], and 6000 [L / h], what distribution pattern shows the measured values of the propagation times T1 and T2? The experiment was conducted. As a result, as shown in FIG. 4, the overall distribution of the propagation times T1 and T2 in the entire flow rate region when 13A gas is the measurement target is approximately distributed on one straight line. confirmed. More precisely, the plot of the measurement result is distributed on the curve, but since the range shown in FIG. 4 is local, it is approximately distributed on a straight line in FIG. It is thought that it is in a state.
[0049]
Furthermore, among the plots of such measurement results, the plot of 25 [L / h] was measured under conditions where slight pulsation occurred, and the distribution pattern of this plot is The distribution pattern is shaken (distributed) in a substantially orthogonal direction with respect to the straight line of the overall distribution. On the other hand, plots of measurement results at flow rates of 1900 [L / h], 3800 [L / h], and 6000 [L / h] are distributed along the straight line of the overall plot for 13A. However, such a distribution pattern is shown when there is no pulsation in the measurement target gas or when low-frequency undulation occurs.
[0050]
In this way, the distribution pattern of the measurement result measured when pulsation occurs is in a direction substantially perpendicular to or intersecting with the linear distribution pattern when pulsation does not occur or when undulation occurs. It will swing in the direction to do.
[0051]
Further, when a change occurs in the temperature of a fluid such as a gas to be measured due to a temperature change in the surrounding environment of the flow rate measuring device, the speed of sound propagating through the fluid also changes. For this reason, even if the flow rate of the fluid is actually constant, the flow velocity value measured at that time may be a value significantly different from the true value due to the temperature change. The phenomenon that the measured values of T1 and T2 change due to such a temperature change was confirmed by experiments. The result is shown in FIG. The distribution of T1 and T2 measured when 13A gas is flowed at each flow rate of 25 to 6000 [L / h] is clearly different in each case where the fluid temperature is -10 ° C, 23 ° C, and 40 ° C. Are distributed in different areas. The distribution fluctuates in a direction substantially perpendicular to or intersecting with the linear distribution pattern corresponding to the temperature change.
[0052]
As described above, the distribution region G is shaken due to pulsation or temperature change, so that it becomes a reference for determining whether or not air is mixed in the gas after taking the shake into consideration. It is desirable to set the predetermined area Gn. Therefore, in order to set the predetermined region Gn including the fluctuation of the distribution region G caused by such pulsation and temperature change, the gas meter according to the present embodiment uses a combination of propagation times under actual gas use conditions. Is learned over a predetermined learning period, and the predetermined region Gn is set to a more realistic setting.
[0053]
Here, it is theoretically analyzed that it is possible to determine whether or not air is mixed in the gas based on the distribution of the propagation times T1 and T2. As described in the section of the prior art, the propagation times T1 and T2 can be generally written as T1 = L / (C + v cos θ) and T2 = L / (C−v cos θ). The relational expression 1 / T1 + 1 / T2 = 2C / L can be obtained. From this relational expression, it is understood that the distribution of the combination of T1 and T2 changes only with the sound velocity C in the fluid under measurement under conditions where the pressure, temperature, etc. of L and the fluid under measurement are constant. The speed of sound C in the fluid generally varies depending on the density ρ of the fluid. Further, since the density ρ varies depending on the component composition of the fluid, in short, the measured propagation time T1 corresponding to the type of fluid such as gas. , T2 distribution changes. Thus, it can be analyzed that the composition of the fluid and the mixing of air can be determined based on the distribution of the propagation times T1 and T2.
[0054]
In addition, since the pulsation generated in the fluid is generally a dense wave, the fluid in a state where the pulsation having a period sufficiently shorter than the time interval in which the propagation times T1 and T2 are measured is locally and instantaneously inherent. Therefore, the distribution of the measured values of the propagation times T1 and T2 deviates from the straight line of the overall measured value distribution when no pulsation occurs, that is, the straight line. It can be analyzed that the distribution fluctuates in the direction intersecting with (in the experimental result shown in FIG. 4, substantially orthogonal). On the other hand, when a pulsation with a period sufficiently longer than the time interval at which the propagation times T1 and T2 are measured, that is, when a so-called undulation occurs, the flow rate is merely slightly increased or decreased at each measurement timing. It can be analyzed that the distribution of the propagation times T1 and T2 measured at that time simply goes up and down along the straight line of the overall distribution of measured values.
[0055]
Further, when air is mixed in a genuine gas such as 13A, the density of the mixed gas is different from the density of the genuine gas. That is, the density ρ of the mixed gas changes in accordance with the amount of air mixed. Therefore, it can be analyzed that the distribution of the measured values of the propagation times T1 and T2 swings in a direction crossing the straight line of the entire measured value distribution corresponding to the amount of air mixed.
[0056]
Note that the predetermined area Gn as an initial value is set by setting one boundary line as shown in FIG. 2 and setting it as one side thereof, as shown in FIG. You may make it set as one band which has. That is, when T1 and T2 included in the upper region Gh and the lower region Gl of the predetermined region Gn are measured, a gas having a composition different from that of a genuine gas or a gas having a different concentration or density is used. Can be determined to be flowing. In addition to the gas meter according to the present embodiment, the technology for detecting such different types of gases and fluids to issue an alarm or shut off the raw material flow rate measuring device used in a chemical plant, for example, The present invention can also be applied to a flow rate measuring device that can handle a plurality of types of fluids, such as a fuel flow rate measuring device for a vehicle engine that uses liquid fuel.
[0057]
Alternatively, the measured propagation times T1 and T2 may be set as one set, and each set may be compared with a predetermined combination, or a plurality of combinations of measured propagation times may be collected and an average value thereof may be taken. The average value may be compared with a predetermined combination.
[0058]
In addition, when it is determined that the combination of the measured propagation times T1 and T2 has deviated from the predetermined combination, in addition to the alarm and the interruption as described above, information carrying the deviation is stored in the management center. You may make it transmit to.
[0059]
As described above, in the gas meter and the flow rate measurement method according to the present embodiment, the comparison unit 410 corresponds to the combination of the forward propagation time and the backward propagation time as a set for a predetermined gas type. Then, it is compared with a predetermined combination area (predetermined area Gn) to determine whether or not the predetermined combination is deviated. If it deviates, it is determined that the gas flowing at that time is different from the predetermined composition or type.
[0060]
That is, the type or composition of the gas deviates from a predetermined one based on the data of the propagation times T1 and T2 measured by the ultrasonic propagation time measuring unit 100 which is an existing general device for obtaining the flow rate measurement value. It is possible to determine whether or not Therefore, it is possible to determine whether or not the composition of the gas to be measured (mixing of air, etc.) is within an allowable range without adding a complicated composition sensor or composition analyzer. When it is determined that the gas to be measured has a composition deviating from a predetermined allowable range, the alarm unit 500 issues an alarm to that effect, and the supply of fluid can be shut off (stopped) by the shutoff valve 600.
[0061]
Further, the learning control unit 420 learns the distribution of the combination of the actually measured forward propagation time T1 and reverse propagation time T2 as a set over a predetermined learning period, and stores the data in the storage unit 430. By storing the values, the normal values of the propagation times T1 and T2 in a state where the gas meter is actually used are automatically learned in a learning control as a predetermined combination. The comparison unit 410 compares the predetermined combination obtained by the learning with the combination of the propagation times measured thereafter, so that the type or composition of the flowing gas deviates from the predetermined one. It is determined whether or not. By such learning control technique, it is possible to make the predetermined combination of the propagation times, which are the reference values for determining the composition of the gas, more precisely in accordance with the actual situation than when setting in advance based on theoretical values and the like. Become.
[0062]
In addition, when a situation occurs in which the type or composition of the gas flowing during the learning period deviates from a predetermined combination that is set as an initial value, the learning control unit 420 stores it in the storage unit 420 until then. The data of the combination of propagation times that have been reset is reset, and then the distribution of the combination of propagation times measured over a predetermined learning period is stored again. Thereby, it is possible to avoid learning data deviating from the type or composition of the gas.
[0063]
Further, during a predetermined time from the gas stop state, even if it is determined that the combination of the measured propagation times deviates from the predetermined combination, the cutoff valve control unit 700 performs the valve cutoff by the cutoff valve 60. Do not execute. Thereby, for example, when pipe construction is performed on the upstream side of the gas meter and the use of the gas is resumed after the completion, so-called air venting can be performed without disturbing the gas containing a large amount of air. .
[0064]
【The invention's effect】
As explained above, claims 1 to 5 The flow measurement method according to any one of claims 1 to 3, 6 Or 10 The flow measurement device according to any one of claims 1 to 3, 11 According to the described gas meter, a combination of a forward propagation time and a backward propagation time measured by an existing general apparatus for obtaining a flow rate measurement value as a set, Distribution of combinations in which the distribution of combinations in which the forward propagation time and the backward propagation time measured over a predetermined learning period are set in correspondence with a predetermined fluid type is stored. Compared to the predetermined fluid, it is determined whether or not it deviates from the predetermined combination. Therefore, a sensor other than the existing ultrasonic generator / vibrator is not attached, and it is different from the predetermined fluid. When a fluid of a different type or composition flows, it can be detected (determined).
[0065]
Further, the flow rate measuring method according to claim 2 or claim 7 The flow rate measuring device or claim 11 According to the described gas meter, when it is determined that the combination of the propagation times deviates from the predetermined combination, the kind or composition of the fluid flowing through the flow rate measuring device at that time is different from the predetermined one. As a result, it is possible to issue an alarm to that effect. In the same case, the flow rate measuring method according to claim 3 or the claim 8 The flow rate measuring device or claim 11 According to the described gas meter, there is an effect that the flow of the fluid to be measured can be blocked.
[0066]
As a result, it is possible to prevent the occurrence of combustion extinction, incomplete combustion, or the occurrence of an erroneous chemical reaction on the downstream side of the gas meter or the flow rate measuring device.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a schematic configuration of a gas meter according to an embodiment of the present invention.
FIG. 2 is a diagram showing a predetermined region Gn corresponding to 13A gas and a propagation time distribution region A corresponding to gas mixed with air.
FIG. 3 is a diagram showing experimental results obtained by examining distributions of combinations in which T1 and T2 of measurement results are one set in the case of 13A gas and air.
FIG. 4 is a diagram showing an overall distribution of propagation times T1 and T2 in the entire flow rate region when 13A gas is a measurement target.
FIG. 5 is a diagram showing an example when a predetermined region Gn is set as one band having an upper limit and a lower limit.
FIG. 6 is a diagram showing experimental results of a phenomenon in which measured values of T1 and T2 change due to a temperature change.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Ultrasonic propagation time measurement part, 200 ... Flow rate value calculation part, 300 ... Flow rate value integration part, 400 ... Determination part, 500 ... Alarm part, 600 ... Shut-off valve, 700 ... Shut-off valve control part

Claims (11)

Measure the forward propagation time when the sound wave is propagated from the upstream side to the downstream side to the fluid to be measured and the reverse propagation time when the sound wave is propagated from the downstream side to the upstream side. In the flow rate measurement method for obtaining the flow rate value of the fluid based on the propagation time of
Storing a distribution of a combination of the forward propagation time and the backward propagation time measured over a predetermined learning period in association with a predetermined fluid type;
Whether or not the combination of the forward propagation time and the backward propagation time obtained by the measurement deviates from the distribution of the combination in comparison with the stored distribution of the combination A flow measurement method comprising a determination process for determining the flow rate. When it is determined that a combination of the forward propagation time and the backward propagation time as a set deviates from the predetermined combination, the measurement target fluid is different from the predetermined fluid. The flow rate measuring method according to claim 1, further comprising an alarm process for issuing an alarm to the effect of at least one of audio information and visual information. When it is determined that the combination of the forward propagation time and the backward propagation time as a set deviates from the predetermined combination, the method further includes a shutoff process for shutting off the flow of the fluid to be measured. The flow rate measuring method according to claim 1 or 2, wherein An initial value of the distribution of the combination is set in advance, and when the combination of the propagation times measured during the learning period deviates from the initial value, the storage of the distribution is reset and the distribution of the combination is newly performed. The flow rate measuring method according to any one of claims 1 to 3, wherein the storage of the data is resumed. When the flow resumes after the fluid flow is stopped, the forward propagation time and the backward propagation time are a set until the predetermined time elapses after the restart. The flow rate measurement method according to claim 3, wherein the flow of the fluid to be measured is not interrupted even if it is determined that the combination deviates from the predetermined combination. Ultrasonic waves that measure the forward propagation time when a sound wave is propagated from the upstream side to the downstream side with respect to the fluid to be measured and the reverse propagation time when the sound wave is propagated from the downstream side to the upstream side In a flow rate measuring device having a propagation time measuring means and a flow rate value calculating means obtained by calculating the flow rate value of the fluid based on the propagation time,
A distribution of a combination of the forward propagation time and the backward propagation time measured over a predetermined learning period as a set is stored in correspondence with a predetermined fluid type and obtained by measurement. A determination means for comparing a combination of the forward propagation time and the backward propagation time with a stored distribution of the combination and determining whether or not the distribution of the combination deviates. A flow rate measuring device comprising: When the determination means determines that the combination of the forward propagation time and the reverse propagation time as a set deviates from the predetermined combination, the fluid to be measured is based on the determination. 7. The flow rate measuring apparatus according to claim 6 , further comprising alarm means for issuing an alarm indicating that the fluid is of a type different from the predetermined fluid based on at least one of audio information and visual information. . A shutoff valve for shutting off the flow of the fluid;
And a shutoff valve control means for controlling the opening and closing operation of the shutoff valve,
When the determination means determines that the combination of the forward propagation time and the reverse propagation time as one set deviates from the predetermined combination, the shut-off valve control means based on the determination The flow rate measuring device according to claim 6 or 7, wherein an operation of a shutoff valve is controlled to shut off a flow of the fluid to be measured. The learning control means is preset with an initial value of the distribution of the combination, and when the combination of propagation times measured during the learning period deviates from the initial value, the learning control means stores the initial value. The flow rate measuring device according to any one of claims 7 to 9, wherein the memory of the distribution is reset and the memory of the distribution of the combination is restarted. After the fluid flow is in a stopped state, the shutoff valve control means sets the forward propagation time and the backward propagation time as a set until a predetermined time elapses after the flow resumes. The flow rate measuring device according to claim 8 , wherein even if the combination is determined to deviate from the predetermined combination by the determination unit, the flow of the fluid to be measured is not interrupted. 11. A gas meter using the flow rate measuring device according to claim 6 , wherein the fluid is a gas.

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