JP4956391B2 - Fluid leak detection method - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention can be generally used in a field where detection of fluid leakage is required in a fluid transportation application in which various fluids are sent toward a fluid using device in which flow rate control is performed. In particular, it is suitable for leak detection and flow rate measurement when fuel is transported to industrial furnaces, boilers or household gas appliances. Furthermore, the application to the use which further improves the safety function of the gas meter with a leak detection function used for home use (so-called “microcomputer meter”) is optimal.

The inner pipe leak detection in the home microcomputer meter is determined to be a gas leak when a state in which the gas flow rate is detected continues for 30 days even in a time zone in which there is no gas demand at midnight. This leak detection logic is used to detect minute leaks. On the other hand, for an excessive flow rate that greatly exceeds the rated flow rate of the gas meter, a breakage of the gas pipe or the like is assumed. In the normally used flow rate range between the minute flow rate and the excessive flow rate, there is no means to detect leakage directly, so it is assumed that the flow rate detected by the gas meter is due to leakage, and the predetermined space explodes due to the leakage. The logic is to shut off the gas supply when the flow rate integration value that reaches the limit is exceeded. Also, if there is a flow rate change within the time limit, it is assumed that the device has been operated or a control operation has been applied, and the time once measured is reset and time integration is started again. This control logic assumes that the flow rate does not fluctuate in case of leakage.
In the above-described method, if normal use without a change in flow rate continues in the normal use flow rate range of the gas meter, it is determined that it is a leak, and there is an inconvenience that the gas is shut off. A typical example of such use is a gas stove, which causes inconvenience that cannot be used for a long time.

  On the other hand, Patent Document 1 relates to a gas appliance discriminating apparatus. In the technique disclosed in Patent Document 1, as shown in FIGS. 3 and 4, the gas supply pressure is activated by active pressure fluctuation means 45. The pressure detection means 41 and the flow rate detection means 42 detect the gas supply pressure and the gas flow rate before and after the pressure fluctuation. And based on this detected value, the flow rate ratio calculation means 46 calculates | requires the ratio of the flow volume which flows into the gas appliance which has a governor (an example of a control means) among all gas flow rates. Based on this ratio and the total gas flow rate, the non-equipment-specific flow rate calculation means 47 calculates the gas flow rate flowing through the gas appliance having the governor and the gas flow rate flowing through the gas appliance without the governor. By comparing the flow rates of the individual gas appliances obtained by the individual gas appliance flow rate calculation means 44, the discrimination means 28 discriminates the presence or absence of the governor equipment.

  Therefore, by using this apparatus, it is possible to determine whether or not the gas appliances provided with the governor device are provided on the downstream side of the gas appliance discriminating apparatus. Furthermore, as described in [0003], it is possible to determine the gas appliance in use and determine whether there is a gas leak according to the gas appliance.

JP 7-151580 A

In the technique disclosed in Patent Document 1, a constant pressure change in one direction, such as a pressure decrease, is applied to a steady flow flowing in a pipe, and a transient response of a flow rate change generated by the application is examined. The presence or absence of governor equipment for the gas equipment arranged on the downstream side is determined.
As a target of fluid leakage detection according to the present application, there may be a case in which a fluid use device is operated on the downstream side and an uncontrolled state of a flow rate including leakage overlaps. That is, a situation may occur in which a control flow rate that is controlled to reduce the pressure change and a non-control flow rate that does not require such control are mixed. Here, the non-control flow rate includes leakage, and includes a use state of a fluid use device that does not include a control means such as a conventional stove. That is, it is necessary to detect the control flow rate and the non-control flow rate with high accuracy. However, when the result shown in FIG. As a result, the calculated value has an error of + 18%. This result is thought to be because an offset remains and an accurate determination cannot be made in a mechanical control device such as a governor or an automatic control device that has only a P (proportional) operation and no I (integral) operation. The determination method including such an error means that when leakage is superimposed on normal use, it cannot be detected if the leakage flow rate is about 20% or less of normal use. I can't say that.
The object of the present invention is to detect the non-controlled state well and to prevent the possibility of fluid leakage even when the leakage that generates the uncontrolled flow is superimposed on the normal use that generates the controlled flow. The object is to obtain a fluid leakage detection method that can be accurately detected.

By achieving a pressure change in the steady flow of the fluid flowing through the pipeline that achieves the above objective, and examining the transient response of the resulting flow rate change, the pressure change is applied to one or more fluid-using devices installed downstream of the pipeline. The first characteristic configuration of the fluid leakage detection method that determines whether or not the control to reduce is incorporated, and outputs the possibility of fluid leakage when it is determined that there is a part that is not incorporated,
In the application of the first pressure change, when it is not clear whether there is a place where control for reducing the pressure change is not incorporated downstream of the pipeline, the pressure change amount from the steady flow pressure is as follows. Applying a second pressure change with a pressure change amount different from the pressure change amount of the first pressure change;
If the flow after each pressure change increases or decreases in response to the increase or decrease of each pressure change, it is judged that there is a part that does not incorporate the control to reduce the pressure change downstream of the pipeline, and fluid can leak. Sexual output.

In general, a fluid use device arranged on the downstream side of a pipeline is accompanied by a control mechanism (control means) for setting and controlling the flow rate of the fluid. This is an inevitable mechanism for maintaining the flow rate at a predetermined value, and many are automatically controlled.
A typical example of an advanced automatic control mechanism is PID (proportional, integral, differential) control, which functions to maintain the flow rate at a set value regardless of disturbance such as pressure change. In this case, in order to perform PID control easily and reliably, a pressure regulating valve upstream of the PID control valve (a valve for controlling the pressure downstream of the valve to maintain the installation value even if the upstream pressure changes: governor). Is often provided.

On the other hand, the simplest one is manual operation using a valve. In this case as well, a pressure regulating valve (an example of a control means) is often used upstream of the manual valve. This is because it is necessary to maintain the flow rate at the (manual) set value even if the supply pressure of the fluid changes.
Therefore, at the minimum, in equipment where a pressure regulator is used, even if the fluid supply pressure (fluid pressure upstream of the pressure regulator: primary pressure) changes, the pressure downstream of the pressure regulator (secondary pressure) In the control operation range of the pressure regulating valve, control to return to the pressure before the change is applied, and as a result, the flow rate is restored to the original value. Of course, an offset (deviation) may remain due to the mechanical configuration.

  Therefore, in the present invention, when the flow rate is substantially constant, first, a change (first pressure change) is applied to the fluid supply pressure using a fluid pressure change device. The amount of change in the supply pressure is within a range in which the flow rate can be controlled by the control mechanism. In this case, the direction of the pressure change by the application may be either the plus side (pressure increasing side) or the minus side (depressurizing side). Then, whether the flow rate is brought about by the operation of the device or not due to the control whether or not the flow rate is to be restored to the state before the application after the application by the control operation of the device installed downstream. Whether it depends on the condition is determined according to a predetermined standard. In the case of leakage, since the flow rate is uncontrolled, it can be used that it changes at a ratio proportional to the square root of the applied pressure change (the ratio of the pressure after the application of the pressure before the application) and does not show the restoring operation. is there.

  This method applies so-called step response in control engineering as the principle of determining the presence or absence of control, so it is desirable to trace the time change (time change) of the flow rate in anticipation of a delay in the step response. . In addition, when the time required for the restoration operation of the flow rate is known in advance or can be regulated by a representative value, it is possible to judge only by two values that can be regarded as a steady state before and after the applied pressure change. Is possible. As the transient response, not only a step response but also an impulse response or a frequency response may be used, and they can be used together as appropriate.

  The present invention basically determines whether the flow rate is due to the use of a device or due to leakage when the flow rate is stable and maintains a constant value for several seconds to several tens of seconds. Therefore, when the flow rate fluctuates, leakage detection by this method is impossible or uncertain. However, the fact that the flow rate fluctuates means that the device is controlled regardless of whether it is automatic or manual, so there is no need to detect leaks, thereby limiting the scope of use of the present invention. It is not done. The fact that there is no problem in such a judgment is proved by the results of the current microcomputer meter logic.

  Now, it may be difficult to distinguish between the uncontrolled state and the controlled state only by the first pressure change. Such a case is a case where an offset remains in the flow rate from the control structure of the control device provided in the fluid-using device, and it is not possible to clearly distinguish between the offset accompanying the control and the uncontrolled state. Therefore, in the present application, the second pressure change is applied to the first pressure change by changing the pressure change amount. The pressure change amount of the second pressure change is different from the first pressure change amount, and does not include an operation of returning the amount of change of the first pressure change by the original amount. In addition, the change is within a range in which the flow rate control by the control mechanism side described so far is possible.

  When multiple pressure changes are applied with different pressure changes in this way, if there is a part that does not incorporate control to reduce the pressure change downstream of the pipeline, each flow rate after the pressure change is In response to the increase or decrease of the pressure change, each increase or decrease in a certain relationship. That is, in general, the offset amount generated by the control does not change greatly in the first and second pressure change amounts as the object of the present application, and the control flow rate generated by the control-side device is not less than the offset amount. The increase or decrease of the flow after the pressure change caused by applying the first and second pressure changes due to the presence of uncontrolled equipment or leakage is considered to be the increase or decrease of the pressure. This is because they appear correspondingly. Therefore, when such a change in flow rate (such as an increase / decrease correspondence between flow rate change and pressure change) appears when multiple pressure changes are applied, control for reducing the pressure change is not incorporated downstream of the pipeline. Judge that there is a location and output the possibility of fluid leakage.

As described above, when applying the first pressure change and the second pressure change,
When the flow rate after the first pressure change and the flow rate after the second pressure change are equal to the ratio of the square root of each pressure after the pressure change, the pipe line It can be determined that there is a part that does not incorporate control for reducing the pressure change downstream. This method is the second characteristic configuration of the present application.

  In giving the pressure change, when the change is given once (first pressure change), as described above, when the leakage included in the uncontrolled state and the device use in the controlled state are superimposed, It is difficult to determine the uncontrolled state. This is because, depending on the use of the device, the flow rate may be restored, but the difference from the original flow rate is small and may be close to the offset amount. In such a case, if a different pressure change (second pressure change) is further applied, it is possible to easily determine the uncontrolled state as shown by the following equation. Hereinafter, a description will be given with reference to FIG.

In general, if the flow rate is not controlled, the relationship between the flow rate before and after applying the pressure change and the pressure is as follows.
Q1 / Q0 = √ (P1 / P0) Equation 1
Here, Q and P represent the flow rate and pressure, respectively, and subscript 0 and subscript 1 represent the state before and after the first change, respectively. ΔP1 = P1−P0 is the amount of change in pressure. Furthermore, when the second pressure change ΔP2 = P2-P0 is given,
Q2 / Q0 = √ (P2 / P0) Equation 2
That is,
Q2 / Q1 = √ (P2 / P1) Equation 3
It becomes.
On the other hand, when control is applied, the control mechanism of the device absorbs the change corresponding to the pressure change amount (if the pressure increases, the pressure loss corresponding to the increase amount is added, and if it decreases, the pressure loss is reduced to reduce the flow rate. Therefore, the values of the pressures P1 and P2 in the leak detection mechanism remain unchanged, and the flow rate is restored to the original value Q0.

  When the non-control state and the control state overlap, the flow rate recovery is partial. Assuming that the flow rate after the first pressure change is Q1, and the flow rate after the second pressure change is Q2, the relationship between the flow rate and pressure before and after each pressure change is given by the following equations 4 to 7 and 8 to 11. It is represented by

Q1 "/ Q0" = √ (P1 / P0) ......... Formula 4
Q0 = Q0 ′ + Q0 ″ ……… Formula 5
Q1 = Q1 ′ + Q1 ″ ……… Formula 6
Q0 '= Q1' ......... Formula 7

Q2 "/ Q1" = √ (P2 / P1) ......... Formula 8
Q1 = Q1 ′ + Q1 ″ ……… Equation 9
Q2 = Q2 '+ Q2 "......... Formula 10
Q1 '= Q2' ......... Formula 11

  That is, Expressions 4 to 7 show the relationship among all gas flow rates Q0 and Q1, control flow rates Q0 'and Q1', uncontrolled flow rates Q0 "and Q1", and pressures P0 and P1 before and after the first pressure change. Equations 8 to 11 show the relationship between the total gas flow rates Q1 and Q2, the control flow rates Q1 'and Q2', the uncontrolled flow rates Q1 "and Q2", and the pressures P1 and P2 before and after the second pressure change.

  Here, (Equation 3) is an equation equivalent to (Equation 8) under the condition that Q1 = Q1 ″ and Q2 = Q2 ″, and therefore, (Equation 8) is represented by each equation on behalf of both equations. Based on the following modification, the following (Equation 12) is obtained.

(Q2−Q2 ′) / (Q1−Q1 ′) = √ (P2 / P1)
(Q2−Q1 ′) / (Q1−Q1 ′) = √ (P2 / P1)
(Q2-Q0 ') / (Q1-Q0') = √ (P2 / P1)
(Q2−Q0 + Q0 ″) / (Q1−Q0 + Q0 ″) = √ (P2 / P1) (Formula 12)

  If the reference pressure is atmospheric pressure and the pressures P1 and P2 of each stage are differential pressures from the atmospheric pressure, the uncontrolled flow rate Q0 ″ (typically the flow rate due to gas leakage) becomes 0 at atmospheric pressure. Therefore, the above (formula 12) becomes the following formula (formula 12 ′).

(Q2-Q0) / (Q1-Q0) = qn2 / qn1 = √ (P2 / P1)... Formula 12 ′
Therefore, by checking whether the ratio of the amount of change in the flow rate in the two pressure states (qn2 / qn1: see FIG. 9) is the square root of the ratio of the applied pressure, the flow rate in the uncontrolled state is the control state. It can be determined whether or not it is superimposed on the flow rate.
When applying this method without using a pressure sensor, the pressure can only be set in advance. However, if the pressure sensor can be used, the measured values should be used as the values of P2 and P1. Therefore, the uncontrolled state (leakage) can be determined more reliably.

  On the other hand, when the flow rate is constant, the first pressure change is applied, and if the flow rate change amount, which is a deviation, exceeds a previously determined determination value (offset value), the uncontrolled state It can also be determined that is superimposed. The flow rate due to leakage included in the uncontrolled state after the pressure change occurs equal to the square root of the ratio of the pressure after the pressure change to the pressure before the change, and the change amount of the flow rate may be larger than the offset amount remaining by the control. Because there are many.

  Regardless of whether the flow rate is not stable, it is possible to investigate the leak by applying pressure changes. This is because in a state where the change is not large or in the gap between the changes, the reliability is inferior, but the determination can be made in a short time, so that the state where the flow rate is about to be restored can be read from the change over time. It can be applied to applications where the flow rate always varies.

When the present invention is applied to a home city gas meter or LP gas meter as a part of the leak detection means, it becomes a problem whether or not the home has non-control equipment.
In recent water heaters and fan heaters, PID control or control close thereto is performed and there is no problem. Equipment that is likely to be a problem is a small water heater, bath tub, stove, grill or rice cooker. Although these devices seem to be uncontrolled because they are manually operated, in fact, even if they are manually controlled devices, in order to improve controllability or ensure stable combustion, a pressure regulating valve (governor) Is used. Therefore, it is possible to determine the use of the device.

  The most problematic is a gas stove (a bite stove, a table stove, a built-in stove, etc.). This is because the gas stove has been sold at a very low price, and it is normal that a pressure regulating valve is not provided for cost reduction. In order to ensure the stability of the melting fire (so as not to extinguish the flame due to over-squeezing, and not to extinguish when it is squeezed) Relatively new. Therefore, in a conventional gas stove, leakage detection cannot be performed by this method. However, the gas stove is a device that is normally used while finely adjusting the thermal power manually, and the time for use at a constant flow rate is not long. The use time becomes longer in the case of stewed dishes. In this case, the gas flow rate is reduced and used. Even if the gas flow rate corresponding to the stew is due to leakage, if ventilation is taken into consideration, the explosion limit is not reached, or even if it reaches, it usually takes a long time. Therefore, if the concept of “time limit”, which will be described later, is used in combination, it cannot be unsafe from the present time.

  In addition to the first or second feature configuration, the third feature configuration of the fluid leakage detection method according to the present invention is the ratio of the pressure change that gives the pressure change according to the flow rate of the steady flow. The purpose is to set the ratio so that the flow rate after the change caused by the pressure change falls within the measurable flow rate with a predetermined accuracy compared to the pressure before being applied.

In carrying out the fluid leakage detection method according to the present application, it is theoretically possible to give any pressure change, but in practice it is necessary to set an appropriate pressure change rate.
As described above, when the flow rate of the fluid is not controlled, the following relationship holds between the pressure and the pressure.
Q / Q0 = √ (P / P0) ......... Formula 13
Here, Q and P represent the flow rate and pressure, respectively, and subscript 0 and non-subscript represent the state before and after the change, respectively.
Therefore, if the flow rate change rate that can be measured stably and reliably by the flowmeter is 10%, for example, the change rate of the applied pressure must be the square of 121%. Thus, it is necessary to determine the pressure change to be applied based on the accuracy of the flow meter and in consideration of the control characteristics of the pressure control mechanism of the instrument such as the instrument governor and the control characteristics such as the offset. It gives a guideline for the rate of pressure change to be set. This also makes it possible to select and set up a booster device or a step-down device.

  According to a fourth characteristic configuration of the fluid leakage detection method according to the present invention, in addition to any one of the first to third characteristic configurations, the pressure changing device to be applied is selectively used according to the flow rate of the steady flow. is there.

  For example, a control valve can be used as a pressure reducing device, and a pump (including a fan, a blower, and a compressor) can be used as a pressure increasing device as a changing device that gives a pressure change to the fluid. However, for example, when the use of the step-down device is stopped, the pressure returns. That is, since the voltage is boosted when viewed from the step-down state, the distinction between the step-down device and the step-up device is merely as convenient as a change device from the state before the operation.

  As the control valve used in this configuration, any type of valve can be used as long as it is a valve that can obtain a state of an intermediate opening degree that is not a fully closed state in addition to a fully opened state. Ideally, solenoid valves, analog valves, diaphragm valves, pulse motor-driven valves (rotary valves), linear valves, etc. that move in a stepwise manner have different valve seat opening areas. A compound valve in which two or more kinds of solenoid valves are combined in parallel may be used. In the case of a compound valve, the rate of change in pressure can be changed depending on the combination of valves to be opened. A so-called Hi-Lo-Off valve can also be used when the intermediate opening is not used in multiple stages.

  On the other hand, the boosting device is typically a pump, but when the fluid is a gas, it is called a fan, a blower or a compressor depending on the degree of boosting. A pressure increase capability of about the same order of magnitude as the pressure of the transport fluid is appropriate. When the pressure is changed in an analog manner, the number of rotations of the motor that drives these may be changed. Alternatively, it is possible to provide the above-described control valve and adjust the increased pressure in the depressurization direction to the desired pressure.

  Even when the change device as described above is used, for example, when a pressure loss is applied by a control valve, it is difficult to perform a large flow rate to a very small flow rate with a single device. The control range is usually about 1/5 and at most 1/10, and the control range is smaller than 1/100 or less of the meter measurement range. Therefore, according to the flow rate of the steady flow (according to the flow rate range), a plurality of change devices such as a large flow rate, a small flow rate, and a micro flow rate are prepared and used properly according to the flow rate range. The fluid leakage detection method according to the above can be executed. The same applies to a pump that is a pressurizing device.

The fifth feature configuration of the fluid leakage detection method according to the present invention is in addition to the first to fourth feature configurations described above.
According to the flow rate of the steady flow, the pressure value to be applied is selected to be positive or negative.

In the case where the flow rate range of the leakage detection target is a small flow rate or a minute flow rate, a highly accurate valve is required to control the small flow rate to the minute flow rate with the control valve. In addition, it is necessary to consider the inconvenience that would cause the stove to disappear due to excessive squeezing. Therefore, when the flow rate is small, it is safer to use a pressurizing device that makes the pressure change positive, for example, a small air pump, instead of using a pressure reducing device that makes the pressure change negative.
Thus, when the technology according to the present application is applied to a gas meter, it may be safer to make the pressure change positive rather than negative. For example, in the case where the stove is fully used as described above, for example, there is a possibility that the stove will disappear if the pressure is lowered there. Therefore, it is appropriate to add a logic that sets a minimum flow rate in advance when leakage detection is performed by a step-down device and does not perform flow rate detection based on this method in a flow rate range smaller than the flow rate. As a result, a step-down device that is less expensive than the step-up device can normally be used, and a flow meter with a leakage detection mechanism can be provided at a low cost.

  On the other hand, in general, when there is leakage, there is a risk that the amount of leakage increases as the pressure increases. Therefore, in such a case, it is preferable to make the pressure change negative (depressurize). Furthermore, when boosting with respect to leakage, the boost width and detection time should be kept to the minimum necessary.

The sixth characteristic configuration of the fluid leakage detection method according to the present invention is in addition to the first to fifth characteristic configurations described above,
The flow rate measurement of the fluid is performed using a flow meter that measures the instantaneous flow rate, and has a function of adding the instantaneous flow rate and outputting the integrated flow rate as an incidental function.
This is because when the present invention is applied, an instantaneous flow rate type such as an ultrasonic flow meter is more convenient for the flow meter. This is because in the case of an instantaneous flow meter, the determination can be completed in a few seconds, and the possibility of receiving a flow rate fluctuation due to the start of use of a new device during the application of the determination can be kept low.
On the other hand, when an integrating flow meter is used as a transaction meter, it is necessary to perform flow integration, which is an essential requirement for practical use.

Now, the leak detection apparatus that uses the leak detection method of the first feature configuration of the present application described so far can be configured as follows.
That is, a pressure change applying means for applying a pressure change to the steady flow of the fluid flowing through the pipe with a time interval;
A transient response detecting means for detecting a transient response of a flow rate change generated in the steady flow due to the application by the pressure change applying means;
From the detection result of the transient response detection means, equipped with a used equipment discrimination means for judging whether or not a control means for reducing pressure change is incorporated in one or a plurality of fluid usage equipment installed downstream of the pipeline,
A leakage information output means for outputting that there is a possibility of fluid leakage when it is determined by the use device discrimination means that there is a part where the control means for reducing the pressure change is not installed downstream of the pipe; ,
In the case where the use device discriminating means cannot clearly determine whether or not there is a portion where control for reducing the pressure change is not incorporated in the downstream of the pipe in the application of the first pressure change, the pressure change The applying means applies the second pressure change with a pressure change amount different from the pressure change amount of the first pressure change with respect to the pressure change amount from the steady flow pressure,
When the flow rate after the two pressure changes increases or decreases corresponding to the increase or decrease of each pressure change, the use device determination means determines that there is a part that does not incorporate control for reducing the pressure change downstream of the pipe. The apparatus can be configured to output the possibility of fluid leakage.

The pressure change applying means applies a pressure change to the steady flow by applying the pressure change. The transient response detecting means detects the transient response of the flow rate change of the steady flow generated as a result. Then, from this detection result, it is determined whether or not a control means for reducing the pressure change is incorporated in one or a plurality of fluid using devices installed downstream of the pipeline. Based on the determination result, the leakage information output means outputs the possibility of fluid leakage. As a result, the possibility of leakage can be detected according to the presence or absence of the control means incorporated downstream of the pipeline.
At this time, in the application of the first pressure change, when it is not clear whether there is a place where the control for reducing the pressure change is not incorporated in the downstream of the pipe (a place where there is no control), When the second pressure change is applied differently from the pressure change amount of the first pressure change, and each flow rate after both pressure changes increases or decreases corresponding to the increase or decrease of each pressure change, the pressure change downstream of the pipeline It is determined that there is a part that does not incorporate control for reducing the amount of fluid, and the possibility of fluid leakage is output.

  More effective leakage detection can be performed by a combination of the detection result by this device and the time limit for each generated flow rate.

  Hereinafter, regarding the determination in the used device determination means, a determination method when the first pressure change is applied and a determination method when the second pressure change is applied will be described.

Judgment method 1 when the first pressure change is applied Regarding the flow rate change that occurs in the steady flow with the application of the pressure change,
One or more fluid-use devices installed downstream of the pipeline when the ratio of the flow rate after the pressure change to the flow rate before the pressure change is equal to the square root of the ratio after the pressure change and the pressure before the pressure change It is determined that there is a portion that does not incorporate a control means for reducing the pressure change.
This discrimination method is a method for discriminating on the basis of a flow rate change that occurs in a situation where the downstream side is completely uncontrolled (including leakage), and this situation can be accurately discriminated. In this case, since the uncontrolled state can be clearly determined, it is not necessary to further apply the second pressure change.

2 Regarding the flow rate change that occurs in the steady flow with the change of pressure,
The fluid or fluids that are installed downstream of the pipe line when the flow rate change includes a flow rate change that attenuates the applied pressure change and the flow rate change amount is larger than a predetermined range of the preset offset amount. It is judged that there is a part where the control means for reducing the pressure change is not incorporated in the equipment used.
This discriminating method is applicable in a situation where there is a control means on the downstream side, but the offset generated by the control is known in advance. Leakage can be accurately determined. Also in this case, since the uncontrolled state can be clearly determined, it is not necessary to further apply the second pressure change.

3 Regarding the flow rate change that occurs in the steady flow with the pressure change,
A pipe line that includes a flow rate change that attenuates the pressure change to which the flow rate change is applied, and the flow rate change amount is within a predetermined range of an offset amount set in advance with respect to the pressure change amount. It is assumed that it is not possible to clearly determine that there is a place where the control means for reducing the pressure change is not incorporated in one or a plurality of fluid use devices 10 installed downstream.
This discriminating method is a method applicable in a situation where there is a control means on the downstream side but the offset generated by the control is known in advance. In this case, since the uncontrolled state cannot be clearly determined, it is necessary to apply the second pressure change.

Control that reduces pressure change to one or more fluid equipment installed downstream of the pipeline when there is a stable flow rate area where it can be determined that the change in flow rate accompanying pressure change has been reduced after application of pressure change It is determined that the means are incorporated.
This discrimination method is a discrimination method for discriminating on the basis of a flow rate change that occurs in a situation where the downstream side is in a completely controlled state, and this situation can be accurately discriminated. In this case, since the uncontrolled state can be clearly determined, it is not necessary to apply the second pressure change.
In this case, when a stable flow rate region is detected by executing the application of the first pressure change and the removal of the same amount of pressure change as a pair, the flow rate after application of the pressure change (before removal), Based on the flow rate after removal (for example, using the average value of both flow rates), it can be confirmed that the flow rate change has been substantially completely diminished, and the discrimination that accurately represents the situation of the pipeline Yes.
For example, it can be confirmed that the flow rate after application of pressure change (before removal) and the average value of the flow rate before application and after removal are substantially the same.

  If the determination is not clear as shown in 3 above, a second pressure change is applied in addition to the first pressure change described above. That is, the pressure change is executed a plurality of times with different change amounts. In this case, a plurality of pressure changes that can be regarded as the first and second pressure changes may be applied, and the number is not questioned. When the flow rate after the pressure change is executed a plurality of times by the used device discriminating unit, the used device discriminating unit increases or decreases in accordance with the increase or decrease of each pressure change. It is determined that there is a part that does not incorporate control for reducing the pressure change downstream, and the possibility of fluid leakage is output.

  In this case, the used device discriminating means determines whether the change in the amount of change from the flow rate of the steady flow is equal to the ratio of the square root of each pressure after the pressure change. It is determined that there is a place where the control to be performed is not incorporated. This corresponds to the leakage detection method of the second feature configuration of the present application described above.

In the leak detection device described so far,
The pressure change applying means applies a pressure change ratio for applying a pressure change according to the flow rate of the steady flow of the fluid at a constant ratio compared to the pressure before the change is applied, and after the change caused by the pressure change. It is preferable that the flow rate be within a flow rate that can be measured with a predetermined accuracy.
By providing the pressure change applying means having this configuration, it is possible to realize a leak detection apparatus that can use the leak detection method having the third characteristic configuration described above.

Furthermore, in the leak detection device described so far,
It is preferable that a plurality of pressure change devices are provided, and the pressure change devices are selectively used according to the flow rate of the steady flow.
In this manner, a leakage detection device that can use the leakage detection method of the fourth feature configuration described above by including a plurality of pressure change devices and using them properly according to the flow rate of the steady flow is realized. it can.

Furthermore, in the leak detection apparatus described so far, it is preferable that the pressure change applying means selects positive or negative pressure values to be applied and removed according to the flow rate of the steady flow.
By providing such a pressure change applying means, it is possible to realize a leak detection device that can use the leak detection method of the fifth characteristic configuration described above.

Further, in the leak detection device described so far, the flow meter constituting the transient response detecting means is a flow meter that measures the instantaneous flow rate by measuring the flow rate of the fluid, and outputs the integrated flow rate by integrating the instantaneous flow rate. It is preferable to have a means as an incidental function.
By configuring the leak detection device in this way, the leak detection method having the sixth characteristic configuration described above can be used.

With the application to a gas meter in mind, an embodiment of the present invention will be described based on the drawings.
FIG. 1 is a flow diagram of the entire system when the present invention is used for fuel flow measurement of a combustion device that is normally burning.
As shown in FIG. 3, the flow meter 1 with a leak detection mechanism includes a flow meter 2 that can measure an instantaneous flow rate, a control valve 3 that applies pressure fluctuation to the flow of fuel, and a shut-off valve 4 that shuts off the fuel when leaking. , A pressure gauge 5 for measuring pressure, at least a storage / calculation / control unit 1a for integrating the flow rate, a communication unit 1b for outputting the flow rate, and a display unit 1c for displaying the flow rate. Here, the storage / calculation / control unit 1a performs a comparison calculation using the leakage detection method according to the present invention in addition to the integration of the instantaneous flow rate. The result is output via the communication unit 1b and the display unit 1c. The communication unit 1b is also used when receiving a fuel cutoff signal or a leakage detection trigger signal from the outside, or outputting the possibility of leakage to an external device.

  FIG. 2 shows a case where there is a leak in the pipeline in the state shown in FIG. 1 while the combustion equipment is stopped. In this case, the flowmeter 1 with the leakage detection mechanism detects the leakage flow rate.

The problem to be solved in the present invention is to determine whether the flow rate measured by the flow meter 2 is due to normal use of equipment equipped with control means installed downstream or due to leakage included in the uncontrolled state. The determination is made at a total of two positions.
However, since there are a wide variety of fluid-using devices 10, it is not possible to make a determination only by measuring the flow rate.

The main thing of the gas equipment which does not have a flow fluctuation in normal use is a manual control equipment such as a gas stove, a small water heater and a stove. Although these gases are adjusted for gas amount immediately after the start of use, they continue to be used at a constant combustion amount for a relatively long time thereafter.
On the other hand, devices with relatively large flow rate fluctuations are devices with built-in automatic control such as large water heaters and fan heaters. This is because these devices always adjust the gas amount in order to maintain the water temperature and the air temperature at the set temperature.

  Control configurations of various gas devices (an example of the fluid using device 10) are shown in FIGS. FIG. 10 is the simplest configuration and is merely provided with a manual adjustment valve 14. Typical examples of the gas appliance having such a configuration are inexpensive ones such as a conventional stove, grilled meat device, okonomiyaki device, and takoyaki device. This type of gas appliance is not provided with a control means.

The device having the configuration shown in FIG. 11 is an example in which a pressure regulating valve 12 (instrument governor) and an instrument plug 13 are provided in order to increase control accuracy and stability while being manually controlled. The pressure regulating valve 12 has an essential function of maintaining the downstream (secondary side) pressure at a set value even if the upstream (primary side) pressure fluctuates. Therefore, a control means is provided. By providing the gas appliance with a governor, the control accuracy is improved as follows.
1. Even if the gas pressure on the primary side fluctuates, the combustion amount is kept constant.
2. Even if the manual control valve 14 is operated, the pressure on the control valve entry side is kept constant, so that the linearity of the control is maintained and the flow rate is easily reduced. (In the absence of governor, if the flow rate is reduced, the piping pressure loss upstream of the control valve will be reduced and the pressure in the control valve will be increased. Furthermore, the flow rate cannot be reduced unless the opening is reduced.)
3. A small fire or a small seed fire will not disappear even if there is a pressure fluctuation (preventing extinction).
4). Can also serve as a backflow preventer.

Some recent stoves, small water heaters, and stoves have built-in appliance governors.
In the stove, the stability of the minimum throttle flow rate is secured (disappearance prevention), and in the small water heater, the flow rate of the pilot burner is stabilized (part of the configuration of the incomplete combustion prevention function is also used by the pilot burner). In the case of using a burner, the flow rate is maintained in a narrow stable combustion range accompanying premixed combustion to ensure stable combustion and to prevent backflow.

As shown in FIG. 12, a device that performs automatic control (feedback control such as PI control and PID control, or a combination of feedback control and feedforward control) by a proportional valve 15 (becomes a fluid using device having a control means). Then, the instrument governor 12 is used for controllability improvement. Even if the instrument governor 12 is not used, the flow rate of these devices always varies depending on the movement of the proportional valve 15. Incidentally, in the figure, 16 is a shut-off valve. Typical examples of gas equipment that performs such control are a large water heater, a central heating boiler, and a fan heater.
In addition to these, some heaters and hot water storage-type water heaters have ON-OFF control or High-Low-Off control, but they all have an instrument governor and are inevitably necessary. Therefore, it is easy to discriminate use of equipment.

  Hereinafter, the storage / calculation / control unit 1a briefly described above will be described with reference to FIG. The storage / calculation / control unit 1a employs a configuration in which measurement information from the pressure gauge 5 and the flow meter 2 is input, and the storage / calculation / control unit 1a is connected to the shutoff valve 4 and the control valve 3. Are configured so that operation commands are sent from each. Here, when it is determined that there is a possibility that leakage has occurred on the downstream side, a shutoff command for the pipeline is output to the shutoff valve 4. A change command for changing the pressure of the fluid is output to the regulating valve 3 in order to detect leakage on the downstream side, which is the main theme of the present application.

The storage / calculation / control unit 1a includes a storage unit 1aa, a flow rate integration unit 1ab, a time limit monitoring unit 1ac, a leakage monitoring unit 1ad, and an input / output unit 1ae as illustrated.
The storage unit 1aa stores the measurement information described above, and stores each generated flow rate required for the time limit monitoring and the time limit corresponding to the generated flow rate as data as shown in FIG. Yes. This data shows the amount of gas leakage (m ³ / h) on the horizontal axis and the time limit (minutes) on the vertical axis. This corresponds to the maximum allowable time (in other words, the time that must be shut off before this time elapses). This data is based on, for example, when a room with a predetermined volume is ventilated so that the air in the room is replaced once every two hours in a situation where a gas leak occurs at a predetermined speed corresponding to the previous leakage flow rate. (Time of ventilation: 0.5 times / h) It is calculated as the limit time during which the gas concentration in the room can be kept below the lower explosion limit concentration. However, on the assumption that the flow rate related to leakage does not change within a time range of about one day or less, if a change is detected in the leakage flow rate, the flow rate is due to the use of non-control equipment such as a stove. Data used on the premise that the time limit will be reset and the time measurement from that point to the time limit will be started again, considering that the time limit is reset as the operation is performed and the flow rate is leaked. It is. In other words, it is basically judged that the equipment is used if there is a flow fluctuation, and if there is no leakage, but there is equipment with no time fluctuation in the flow, so even if it is judged that there is a leak, it will be shut off. There will be a time limit as a grace period.
Furthermore, in this storage unit 1aa, data necessary for leak detection described in detail below (pressure change to be applied to the flow rate of each steady flow (not only when a single change is applied, but also multiple changes) In addition to the pressure change amount in the case of giving, according to the flow rate, if the flow rate is smaller than the predetermined flow rate, the pressure change is always positive.

  The flow rate accumulation unit 1ab sequentially accumulates instantaneous flow rates that are measurement information of the flow meter 2 to obtain a flow rate that flows over a predetermined period. The integrated flow rate integrated by the flow rate integration unit 1ab is stored in the storage unit 1aa in association with the time of measurement. The accumulated flow accumulated in this way is separately used for charging for fuel gas consumption in each household, and for investigating the fluid consumption trend in each household.

The time limit monitoring unit 1ac changes from each generated flow rate generated downstream (including a state in which a certain amount of fluid is consumed (including a state in which no fluid is consumed) to a certain amount, and so on. If there is an increase in the flow rate, the uncontrolled flow rate included in this increase becomes a single generated flow rate), and the duration of the generated flow rate is monitored and depends on the flow rate of each generated flow rate Thus, it is monitored whether or not the duration of each generated flow rate exceeds the time limit with respect to the time limit determined in advance. Here, when obtaining the uncontrolled flow rate included in the above increase, a constant pressure change is given to the increased steady flow at the stage where the flow rate is increased, and the pressure P0 before and after the pressure change is determined. , P1 and the flow rates Q0 and Q1, the uncontrolled flow rate Q0 ″ is obtained by the following equation (14).
Q0 ″ = (Q1−Q0) / (√ (P1 / P0) −1) Equation 14
Therefore, in the time limit monitoring according to the present application, time limit management is performed only for the true leakage flow rate. And when the time limit is exceeded, the cutoff information with respect to the cutoff valve 4 demonstrated previously is produced | generated. The shut-off information generated in this way is sent to the input / output unit 1ae, and is sent to the shut-off valve 4 as a shut-off command after comprehensive judgment with leak possibility information from the leak monitoring unit 1ad as will be described later.

The leakage monitoring unit 1ad will be described in detail below.
As can be seen from the figure, the leakage monitoring unit 1ad includes a pressure change applying unit m1, a transient response detecting unit m2, a used device determining unit m3, and a leakage possibility information output unit m4.

The pressure change applying means m1 flows through the pipeline according to the pressure change data stored in the storage unit 1aa in accordance with a preset processing timing for executing leakage detection or a trigger signal input from an external device separately. Pressure change application information for applying a pressure change to the steady flow of the fluid at intervals is generated. This pressure change giving information is sent to the regulating valve 3 to give a pressure change to the steady flow flowing in the pipeline in a predetermined pattern to be described later.
The form of the pressure change by the pressure change applying means m1 changes the degree of applying the pressure change according to the flow rate of the steady flow flowing through the pipe, and the ratio of the applied pressure change is compared with the pressure before the change is applied. Thus, it is configured to have a certain ratio. More specifically, the flow rate after the change caused by the pressure change according to each flow rate is within a control range of the control means so as to be within a flow rate that can be measured with a predetermined accuracy.

The form of the pressure change by the pressure change applying means m1 is configured to select the value of the applied pressure as positive or negative according to the flow rate of the steady flow. That is, when the flow rate is smaller than a predetermined flow rate (for example, 0.05 m ³ / h), the pressure change is positive in the direction of increasing the flow rate, and the flow rate is larger than the predetermined flow rate (for example, 0.05 m ³ / h). In this case, the pressure change is negative in the direction in which the flow rate decreases.

  Furthermore, when it is difficult to determine whether there is a part where control for reducing the pressure change is not incorporated in the downstream of the pipeline due to the application of the first pressure change, the application of the pressure change is changed to the amount of change. It is configured to perform multiple times by mistake. That is, as shown in FIG. 9, the pressure after the first pressure change is P1, and the pressure after the second pressure change is P2. Here, as for the relationship between P1 and P2, the latter is preferably about twice (for example, 1.75 to 2.25 times) the former.

  The transient response detecting means m2 detects the transient response of the flow rate change that occurs in the steady flow as the pressure change applying means m1 works to apply and remove the pressure change, and will be described by taking FIG. 4 as an example. The change in the flow rate indicated by the solid line corresponding to the pressure change is detected with respect to the application and removal of the pressure indicated by the alternate long and short dash line. The detection range by the transient response detecting means m2 includes the flow rate Q1 in the transient response region T1 in which the flow rate has changed, and the flow rate reached through the transient response (that is, the stable flow rate region T2 in which the flow rate returns to the flow rate before the pressure change). Flow rate Q2), and includes both changes in application and removal.

  Based on the detection result of the transient response detecting means m2, the used equipment determining means m3 determines whether or not the control means for reducing the pressure change is incorporated in the single or plural fluid using equipment 10 installed downstream of the pipeline. To do. Specifically, the following judgments are made respectively.

First, the used device discrimination relating to the application of the first pressure change is performed by any one of the following 1-4.
When the ratio of the flow rate after the pressure change to the flow rate before the pressure change is equal to the square root of the ratio of the pressure after the pressure change and the pressure before the pressure change with respect to the flow rate change that occurs in the steady flow with the application of the pressure change (See FIG. 7), it is determined that there is a place where the control means for reducing the pressure change is not incorporated in one or a plurality of fluid use devices installed downstream of the pipeline.
In this case, since the uncontrolled state can be clearly determined, it is not necessary to apply the second pressure change.

2 With regard to the flow rate change that occurs in a steady flow with the application of a pressure change, when the flow rate change includes a flow rate change that completely attenuates the applied pressure change, one or more fluid use devices installed downstream of the pipeline 10, it is determined that a control means for reducing the pressure change is incorporated. More simply, after the pressure change was applied, a stable flow rate region appeared where it was possible to determine that the flow rate change before and after the pressure change was almost completely diminished (the flow rate returned to the pre-apply flow rate). In the case (see FIG. 4 and FIG. 6), it is determined that the control means for reducing the pressure change is incorporated in one or a plurality of fluid use devices installed downstream of the pipeline. In this case, it can be determined that there is no part that is not incorporated. Therefore, since the control state can be clearly determined, it is not necessary to apply the second pressure change.

3 With regard to the flow rate change that occurs in the steady flow with the application of the pressure change, the flow rate change includes a flow rate change that attenuates the pressure change to which the flow rate change is applied, and the flow rate change amount is set in advance with respect to the pressure change amount. Control that reduces pressure change to one or a plurality of fluid using devices 10 installed downstream of the pipe line when the offset amount is larger than a predetermined range (for example, 1.3 times) (see FIGS. 5 and 8). It is determined that there is a place where no means are incorporated. Also in this case, since the uncontrolled state can be clearly determined, it is not necessary to apply the second pressure change.

4 With regard to the flow rate change that occurs in the steady flow with the application of the pressure change, the flow rate change includes a flow rate change that attenuates the pressure change to which the flow rate change is applied, and the flow rate change amount is set in advance with respect to the pressure change amount. Control to reduce pressure change to one or a plurality of fluid use devices 10 installed downstream of the pipe line when the offset amount is within a predetermined range (for example, within a range of 0.7 to 1.3 times). It is assumed that it is not possible to determine whether or not there is a part where no means is incorporated. This case corresponds to an example in which it is difficult to make a determination in the present application, and includes cases where the determination cannot be clearly performed in the determination methods 1 to 3 described so far. A second pressure change needs to be applied. Therefore, in the present application, the second pressure change is applied when the case where the determination is difficult as described above basically in relation to the offset occurs.
Then, when a plurality of pressure changes of the first and second pressure changes are executed in this way, each flow rate after the pressure change increases or decreases corresponding to the plurality of pressure changes. It is determined that there is a part that does not incorporate control to reduce the pressure change.
Specifically, the pressure change applying unit m1 applies the pressure change a plurality of times (at least the first time and the second time) with different amounts of change, and the flow after the pressure change is executed a plurality of times. When the ratio of the amount of change from the flow rate of the steady flow is equal to the ratio of the square root of each pressure after the pressure change, it is determined that there is a part that does not incorporate control for reducing the pressure change downstream of the pipe.

  If the leakage possibility information output means m4 determines that there is a part where the control means for reducing the pressure change is not incorporated in the downstream of the pipe line by the use device determination means m3, there is a possibility of fluid leakage. Information on the possibility of leakage is generated. When this leakage possibility information is generated, this information is sent to the input / output unit 1ae.

  The input / output unit 1ae waits for the elapse of the time limit for each generated flow rate from the time limit monitoring unit 1ac in a situation where the leakage possibility information is received from the leak monitoring unit 1ad. Then, on receipt of leakage possibility information, when the above-described cutoff information is sent, a cutoff command is output in a state in which the time limit has been confirmed for at least one generated flow rate.

The above is the description of the configuration of the storage / calculation / control unit 1a.
Hereinafter, a fluid leakage detection method according to the present application will be described with reference to the drawings.
If the flow rate of the fluid passing through the flow meter 2 does not change in a time of several seconds to several minutes, the flow rate can be determined by determining whether the flow is caused by the steady use state of the device or caused by leakage. It is impossible just to have. Therefore, in the fluid leakage detection method according to the present application, the pressure loss (pressure loss) of the fluid is reduced by adjusting the opening degree of the control valve 3 in accordance with the command from the memory / calculation / control unit 1a described above. To increase the downstream pressure and then increase and decrease the pressure. In this way, there will be a difference in transient response and subsequent steady flow between the controlled and non-controlled devices.

  That is, as shown in FIG. 4, when the pressure of the fluid is increased, when a device with a built-in device governor or the like and whose flow rate is controlled is used downstream, this pressure change can be controlled and absorbed by the device governor. If it is set as the range, a transiently increasing change in the flow rate is observed, then the flow rate is decreased and returned to the original flow rate. Then, when the fluid pressure is decreased, the opposite response is observed. That is, between the application and removal of such a pressure change, there is a stable flow rate region where it can be determined that the flow rate change before and after the application of the pressure change has been almost completely diminished (the flow rate has returned to the flow rate before the application). appear. However, in a relatively simple control such as governor, as shown in FIG. 5, the flow rate does not completely return to the original state, and an offset value (denoted as offset in FIG. 5) may remain. When is removed, the offset value starts from a state where the offset remains, and the state where the opposite offset value remains is reached. When the pressure increase / decrease offset values are the same, the flow returns to the original flow rate. In this case, even when the offset values are different, the difference is generally not large.

  In the case where high-precision control such as PID control is performed in a device installed downstream, an offset value does not remain particularly by I (integration) operation, and if it is D (differential), as shown in FIG. Transient characteristics with an overshoot can be obtained.

  On the other hand, when there is no control means in the leakage or downstream equipment, as shown in FIG. 7, after the transient delay, an increase or decrease in the flow rate equal to the square root of the pressure change amount is observed. . The flow rate change when the flow downstream from the flow meter 2 is uncontrolled is shown in FIG. 7 as an uncontrolled flow rate qn (the description format of this uncontrolled flow rate is the same in FIGS. 8 and 9). Accordingly, it is possible to determine whether or not the fluid flow rate is controlled by applying a step-like change to the fluid pressure and measuring the transient response characteristics (including the subsequent steady flow rate).

  If leakage occurs during operation of the fluid using device 10, the flow rate measured upstream is the sum of the flow rates of both. Now, assuming that the device is controlled by a governor, and a leak overlaps with it, a transient response of the flow rate as shown in FIG. 8 is seen when the fluid pressure is increased or decreased. That is, the flow rate of the amount used by the equipment is controlled so as to cancel out the increase / decrease, but the increased amount due to leakage remains, resulting in a difference of “uncontrolled flow rate qn” shown in the figure. When this difference is small, leakage cannot be detected unless it can be distinguished from the offset value shown in FIG. 5, and the value as a leakage detection method is reduced. Therefore, this offset is distinguished by comparison with a general offset amount in a gas device that has been known in advance.

Furthermore, as another countermeasure, as shown in FIG. 9, the pressure is changed a plurality of times including the first pressure change and the second pressure change, and the steady flow rate value at each pressure (the flow is stabilized). The amount of change (qn1, qn2) from the original flow rate (flow rate of the steady flow before the pressure change) of the steady state is equal to the square root of the ratio of the pressures P1, P2 (qn2 / qn1). = √ (P2 / P1)). In a controlled device, even if the pressure changes to multiple values, the flow rate will be restored to the original value in any case, but the leakage will increase in proportion to the square root of the pressure change. It is.
Accordingly, even when leakage or use of uncontrolled equipment is superimposed on normal use of controlled equipment, it is possible to discriminate both.

  Currently, in household gas appliances, uncontrolled appliances remain on the stove, but recently, those with built-in appliance governors are beginning to appear, but on the other hand, they are devices with a short replacement cycle. Therefore, it can be expected that a situation where there is no uncontrolled stove will be realized in a relatively short period of time. Therefore, it is considered that the situation in which these devices are the limitations of this leakage detection method will eventually be solved. Furthermore, for such a stove, it is essential to provide a timer for forgetting to turn off, and when the stove is continuously operated for a predetermined time or more, it is configured to forcibly stop the operation. The worry will disappear in the future.

On the other hand, in the current situation where non-control devices such as a stove are mixed, it is possible to use the logic of a conventional microcomputer meter together.
Therefore, the logic to be used in combination with the leakage detection method of the present invention is as follows.
1. If a large flow rate exceeding the meter's rated flow rate occurs, it may be considered immediately because there is a possibility of a large flow rate leak such as broken pipes or disconnection.
2. When the flow rate fluctuates within the meter rated flow, it is considered that the device is used.
3. If the flow rate without fluctuation continues, there is a possibility of leakage, so it is considered as leakage at the stage where the limit time set in advance in relation to the flow rate has elapsed until reaching the explosion limit concentration.
When a non-control device such as a stove is used at a constant flow rate for a long time in a simmered dish or the like, it is regarded as a leak by using the third logic. As a result, it is not more unsafe than the conventional microcomputer meter.
On the other hand, in a long-time use of a stove or the like which is a controlled device, the conventional microcomputer meter can eliminate a malfunction that is leaked in spite of being used by the third logic. Furthermore, in the microcomputer meter, even if there is a leak, it cannot be determined whether it is used or leaked, and eventually the leak continues until the time is limited by the third logic. In this leak detection method, Since it is possible to determine the control device in a short time (several seconds to several tens of seconds) when there is no installation of uncontrolled devices in newly constructed properties, etc., leakage will not continue. , Improve safety.
In addition, each formula demonstrated so far in this invention is a formula formed about the gas flow rate and gas pressure in the location immediately before the gas equipment in a gas supply path. Therefore, for the gas flow rate and gas pressure at a location where the distance to the gas device is large and the pressure loss in the gas supply path to the gas device is large, an error occurs in the calculation according to the above formulas. In practice, the distance between the gas meter and the gas equipment is practically short, so the error is not particularly problematic, and the methods described so far can be employed.

[Another embodiment]
(1) In the above embodiment, an example in which a single regulating valve 3 is provided as a flow meter with a leakage detection function and a pressure change is applied by adjusting the opening of the regulating valve 3 has been shown. As shown in FIG. 14, a plurality of fluid use devices (a stove, a small water heater, and a water heater) are installed on the downstream side of the flow meter, and the fluid consumption of these fluid use devices is relatively wide. When the range is exceeded, there is a case where the flow rate of the fluid flowing through the pipe line is distributed in a relatively large range during the operation of these fluid using devices.
When there is such a distribution, it is not appropriate to apply a pressure change with a single device to execute the leak detection method of the present application. That is, a single device may not be able to accurately apply a pressure change. Therefore, in such a case, as shown in FIG. 14, a plurality of control valves 3a, 3b, 3c corresponding to different flow ranges are provided, and a plurality of pressures applied and removed according to a steady flow rate. It is preferable to use different change devices. In this figure, 2 indicates an ultrasonic flowmeter.
(2) In the above embodiment, as shown in FIGS. 4 to 9, as the pressure change, the positive pressure change that mainly increases the pressure is applied, and then the pressure decreases. In this example, the pressure change is removed in the direction of the pressure. As the pressure change, first, a negative pressure change that decreases the pressure is applied, and then the pressure change is removed (the pressure increases). It is also possible to do that.
When applying a pressure change to the positive side and then removing it, it can be suitably applied when the flow rate is less than the predetermined flow rate, in order to avoid extinguishing the flame, etc., and applying the pressure change to the negative side and then removing it In this case, it can be suitably applied when the flow rate is higher than a predetermined flow rate in order to avoid excessive leakage.
The city gas and gas meter (microcomputer meter) have been described above as examples, but the present invention can be applied to LPG in the same manner. The present invention can also be applied to fuel gas transport pipes, oil supply pipes connecting oil storage tanks such as heavy oil and kerosene and combustion equipment. Furthermore, it can be applied to piping such as water, and the application range is not limited to city gas.

  In the case where there is a high possibility that leakage has occurred on the downstream side, a fluid leakage detection method capable of accurately detecting the possibility of fluid leakage could be obtained.

Schematic flow diagram when the present invention is applied to a pipe leading to a fluid-using device (when the device is normally burned) Schematic flow diagram when the present invention is applied to a pipeline leading to a fluid-using device (when there is a leak in the pipeline) The conceptual diagram which shows the structure of the flowmeter with a leak detection mechanism of this invention Diagram showing the transient response of the flow rate when the pressure changes in a device that uses a simple control device (governor) (ideal state) A diagram showing the flow rate transient response when pressure changes in a device that uses a simple control device (governor) (with offset) The figure which shows the flow rate transient response at the time of the pressure change of the equipment where PID control is done using the proportional control valve Diagram showing flow rate transient response when pressure changes in case of leakage Diagram showing the transient flow response at pressure change when leakage and use of equipment with simple control equipment (governor) are superimposed The figure which shows the flow rate transient response at the time of the 1st and 2nd pressure change in case the use of the equipment in which the leak and the simple control equipment (governor) are used overlap. Flow diagram inside the instrument representing the configuration of uncontrolled equipment Flow diagram in the machine representing the configuration of manual equipment with built-in pressure regulator Flow diagram inside the instrument showing the configuration of automatic control equipment Explanatory diagram showing the time limit for each gas leak amount Flow diagram with multiple control valves for different flow rates

Explanation of symbols

1 ... Flow meter with leak detection mechanism 2 ... Flow meter 3 ... Control valve (pressure change device)
4 ... Shut-off valve 5 ... Pressure gauge 10 ... Combustion device (fluid equipment)
11 ... Combustor 12 ... Pressure regulator (instrument governor: control means)
13 ... Appliance plug 14 ... Manual adjustment valve 15 ... Control valve (control means)
16 ... Shut-off valve (solenoid valve)

Claims (6)

Control that reduces the pressure change is incorporated into one or more fluid equipment installed downstream of the pipe by applying a pressure change to the steady flow of the fluid flowing through the pipe and examining the transient response of the resulting flow change. Is a fluid leakage detection method that outputs the possibility of fluid leakage when it is determined that there is a part that is not incorporated,
In the application of the first pressure change, when it is not clear whether there is a place where control for reducing the pressure change is not incorporated downstream of the pipeline, the pressure change amount from the steady flow pressure is as follows. Applying a second pressure change with a pressure change amount different from the pressure change amount of the first pressure change;
If the flow after each pressure change increases or decreases in response to the increase or decrease of each pressure change, it is judged that there is a part that does not incorporate the control to reduce the pressure change downstream of the pipeline, and fluid can leak. A fluid leakage detection method that outputs the characteristics. When applying the first pressure change and the second pressure change,
When the flow rate after the first pressure change and the flow rate after the second pressure change are equal to the ratio of the square root of each pressure after the pressure change, the pipe line The fluid leakage detection method according to claim 1, wherein it is determined that there is a part where control for reducing the pressure change is not incorporated downstream.   The ratio for applying a pressure change according to the flow rate of the steady flow is a constant ratio compared to the pressure before the pressure change is applied, and the flow rate after the change caused by the pressure change is within a flow rate that can be measured with a predetermined accuracy. The fluid leakage detection method according to claim 1 or 2, wherein the ratio falls within a range.   The fluid leakage detection method according to any one of claims 1 to 3, wherein a change device that changes pressure is selectively used according to the flow rate of the steady flow.   The fluid leakage detection method according to any one of claims 1 to 4, wherein a value of a pressure change is selected to be positive or negative according to the flow rate of the steady flow. The fluid according to any one of claims 1 to 5, wherein the flow rate measurement of the fluid is performed using a flow meter for measuring an instantaneous flow rate, and has a means for integrating the instantaneous flow rate and outputting the integrated flow rate as an auxiliary function. Leak detection method.

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