WO2005080935A1 - Leakage checking method and device - Google Patents

Abstract

A leakage checking method and device for checking leakage of a container such as a pipe efficiently while removing the influence of the temperature variation in the container effectively. The leakage checking device comprises a means (15) for increasing/decreasing the pressure in a container the leakage of which is being checked, a means (14) for measuring the pressure variation in the container, a means for increasing/decreasing the pressure in the container in a specified time series, and an operating means for calculating correlation between a signal obtained by the pressure measuring means and a reference signal corresponding to the time series. The device is characterized in that leakage of the container is detected based on the correlation calculated by the operating means. Preferably, the device is characterized in that the reference signal is so composed that the signal during pressure increasing/decreasing step and the signal during the transient response period immediately after the pressure increasing/decreasing step are excluded from the calculation of the correlation.

Description

 Specification

 Leak inspection method and device

 Technical field

 The present invention relates to a leak inspection method and device used for diagnosing a state of a container including a pipe for supplying a gas or a liquid, and particularly to detecting a leak of a gas or a liquid from inside the container. The present invention relates to a leakage inspection method and apparatus.

 Background art

 [0002] Containers including a large number of pipes are installed in buildings such as homes and factories. These containers include gas, liquid liquefied petroleum gas, drinking water, refrigerants for air conditioning, gas and solutions for plants, and the like. It is used to supply or store various gases or liquids throughout the building. However, the container containing these pipes gradually deteriorates due to mechanical or chemical action over a long period of use, and in some cases, an opening occurs in the container wall, and the container is introduced into the container. There is a possibility that the problem of leakage of gas or liquid may occur.

 [0003] Conventionally, a leak test for a container such as a pipe is performed by closing the container and injecting a gas or a liquid from an inlet provided in a part of the container such as a supply port or an outlet and communicating with the container. It is performed by measuring the pressure change in the container for more than a predetermined time after the inside of the container is set to a pressure higher than the outside of the tube.

 If, for example, the pressure shows a decreasing trend in the measurement results, it is assumed that gas or liquid is flowing out of the container, and it is determined that there is an opening such as a crack in a part of the wall surface of the container. Was.

 [0004] However, the change in the pressure in the closed vessel changes depending not only on the leak but also on the influence of the temperature change in the vessel.

 For this reason, accurate inspection requires a measurement that takes into account the effects of temperature fluctuations. Conventionally, when measuring the pressure change in a container, a simple measuring device that simultaneously measures the temperature change in the container Because there is no measurement, the time when the temperature change is small is selected and measured, which causes the efficiency of the inspection work to be significantly reduced.

[0005] The present applicant has disclosed in Patent Document 1 below a pressure capable of compensating for a temperature change. A measurement method and device were proposed.

 In the invention according to Patent Document 1, in a pressure measurement method for measuring the internal pressure of a pipe for supplying a gas or a liquid, the pressure in the pipe is adjusted to be equal to the pressure outside the pipe, and the pipe is closed. By measuring the pressure change inside the pipe due to the temperature change, or correcting the pressure measurement value inside the pipe based on the measured temperature of the gas or liquid in the pipe or the measured temperature of the pipe, It removes the effects of change.

 Patent Document 1: Japanese Patent Application Laid-Open No. 2003-227773

[0006] In small-volume gas pipes such as those for general households, since leak inspection can be performed in a relatively short time, it is assumed that the temperature change has a substantially constant slope throughout the inspection time. It is possible. Therefore, the pressure inside the pipe is adjusted to be the same as the pressure outside the pipe, the pipe is closed, the amount of pressure change inside the pipe due to temperature change is measured, and a leak test is performed based on this measurement result. It is possible to eliminate the effects of temperature changes over time.

 However, in large-capacity piping facilities such as apartment houses, hospitals, and schools, a long time is required for leakage inspection, and the slope of the temperature change may fluctuate within the inspection time. For this reason, if the result of adjusting the inside and outside pressures of the pipes so as to be equal to each other is used, the influence of the temperature change may not be removed in some cases. Furthermore, when the temperature of the pipe itself is detected, there is a problem that, as the capacity of the pipe increases, the temperature change tends to vary depending on the location of the pipe, and it is difficult to achieve sufficient temperature compensation. Have.

[0007] Further, in the invention related to Patent Document 1, the operation of adjusting the pressure in the pipe to be equal to the pressure outside the pipe is usually realized by opening the pipe to the outside air. If the pressure inside and outside the pipe is to be balanced without using this means of opening, large-scale equipment and precise measuring equipment will be required. However, in large-scale facility gas pipes, a large amount of flammable gas is released into the atmosphere, so opening pipes to the atmosphere and making the pressure in the pipe equal to the atmospheric pressure is dangerous. In addition, since air is introduced into the pipe by opening the pipe to the atmosphere, it is necessary to perform an air purge before resuming use after inspection. With large-capacity piping, the air purging operation is very large and difficult. For the same reason, leak inspection of containers storing toxic gas, corrosive gas, etc. In this case, the container cannot be opened to the outside air in order to return the pressure to the atmospheric pressure. Disclosure of the invention

 Problems to be solved by the invention

 [0008] The problem to be solved by the present invention is to solve the above-mentioned problems, and to effectively remove the influence of a temperature change in a container, which can be achieved only by efficiently performing a leak inspection of a container such as a pipe. It is an object of the present invention to provide a leakage inspection method and apparatus.

 Means for solving the problem

[0009] In order to solve the above-described problem, in the invention according to claim 1, a pressure increasing / decreasing step of increasing or decreasing the pressure of a container to be inspected for leakage in accordance with a predetermined time sequence and measuring a pressure change in the container are measured. Calculating a correlation between a signal measured in the pressure measuring step and a reference signal corresponding to the time series, and detecting leakage of the container based on the correlation.

[0010] The invention according to claim 2 is characterized in that, in the leakage inspection method according to claim 1, the signal measured in the pressure measuring step is a time-varying signal of pressure. I do.

 [0011] Further, in the invention according to claim 3, in the leakage inspection method according to claim 1 or 2, the reference signal is a signal in a transient response period at the time of the pressurization / decompression step and immediately after the step, except for the correlation calculation power. It is characterized by being constituted as follows.

 [0012] In the invention according to claim 4, in the leak inspection method according to any one of claims 1 to 3, the pressurizing and depressurizing step includes a substance having the same component as a substance contained in a container to be inspected for leakage, or It is characterized in that a part of substances contained in the component is supplied or sucked.

 [0013] Further, in the invention according to claim 5, according to the leak inspection method according to claim 4, the suction is performed by removing the recovered material or the partial material from a container to be tested for leakage. The adsorbed material is adsorbed, and the supply is performed by releasing the adsorbed material to the adsorbed material or releasing the adsorbed material to the same component or the same component as the substance component contained in the container to be inspected for leakage from another container. It is characterized in that a part of the contained substances is supplied.

[0014] Further, the invention according to claim 6 includes a pressure increasing / decreasing means for increasing or decreasing the pressure of a container to be inspected for leakage, a pressure measuring means for measuring a pressure change in the container, and a pressure increasing / decreasing means for the container. Pressurizing / depressurizing control means for controlling the pressurizing / depressurizing means for performing according to a predetermined time sequence; Calculating means for calculating a correlation between the signal obtained by the pressure measuring means and a reference signal corresponding to the time series; detecting leakage of the container based on the correlation calculated by the calculating means; A leakage inspection apparatus characterized in that:

 [0015] In the invention according to claim 7, in the leak inspection apparatus according to claim 6, the leakage of the container is determined based on the volume of the container to be inspected and the correlation calculated by the arithmetic means. Characterized in that it has means for calculating the size of.

 [0016] In the invention according to claim 8, in the leak inspection apparatus according to claim 7, the volume of the container is such that when the container is pressurized or depressurized, it flows into or out of the container. It is calculated based on the value measured by the means for measuring the flow rate of the fluid to be measured and the pressure measuring means for measuring the pressure change in the container.

 [0017] In the invention according to claim 9, in the leak inspection apparatus according to claim 6, the caro pressure reducing means includes a substance or a substance having the same component as a substance contained in a container to be inspected for leakage. A supply means for supplying a part of substances contained in the component or a suction means for suctioning is connected.

 [0018] In the invention according to claim 10, in the leak inspection apparatus according to claim 9, the suction means adsorbs the substance or a part of the substance collected from a container to be inspected for leakage. The supply means releases the substance adsorbed on the adsorbent material, or contains the same component as or contained in the component contained in the container to be inspected for leakage. It is characterized in that it supplies other containers that contain some substances to be supplied.

 The invention's effect

 [0019] According to the invention of claim 1, the pressure measured using the reference signal corresponding to the time series of pressurization or depressurization in the pressurization or depressurization step of pressurizing or depressurizing the container to be inspected for leakage. From the change signal, it is possible to identify the correlation component related to the leak and detect the leak without being affected by the temperature change. According to the present invention, since the temperature compensation is performed in parallel during the leak inspection, the leak inspection of a large-capacity container requiring a long time for the inspection can be accurately performed.

[0020] Further, according to the invention of claim 2, it is possible to correlate the time change signal of the pressure with the reference signal. Thus, the pressurizing / depressurizing step and the pressure measuring step can be simplified.

 [0021] Further, according to the invention of claim 3, the reference signal is configured so as to exclude the signal in the transient response period immediately after the compression / decompression step from the correlation calculation from the correlation calculation. Even if the pressure inside the container changes suddenly during the transient response period immediately after, the pressure change which is a noise at the time of leakage inspection is removed, and only the pressure state necessary for leakage inspection can be effectively detected, and accuracy is improved. It is possible to realize high leakage inspection.

 [0022] Further, according to the invention according to claim 4, in the pressurizing and depressurizing step, a substance having the same component as the substance component contained in the container to be inspected for leakage or a part of the substance contained in the component is supplied or sucked. As a result, it is possible to prevent a substance different from the substance contained in the container from being taken into the container, and it is possible to omit operations such as replacing the substance contained in the container after the inspection, and to reduce the flammability. Leak inspection can be performed without releasing gas or toxic gas into the atmosphere.

 [0023] Further, according to the invention according to claim 5, the suction operation can be performed efficiently by causing the substance collected from the container to be inspected for leakage or a part of the substance to be adsorbed to the adsorbent material by the suction. This makes it possible to stably hold the adsorbed substance. In addition, in the supply, the above-mentioned adsorbed material is released by the adsorbing material to supply a substance having the same component as the substance contained in the container to be inspected for leakage or a part of the substance contained in the component. There is no need to arrange another container such as a gas cylinder. Alternatively, in the above-mentioned supply, when a substance having the same component as the substance contained in the container to be inspected for leakage from another container or a part of the substance contained in the component is supplied, the adsorbed substance is released. It is possible to omit special measures for this.

 [0024] Further, according to the invention of claim 6, similarly to the invention of claim 1, from the measured pressure change signal using the reference signal corresponding to the time series of the pressurization or decompression, It is possible to provide a leakage inspection device capable of identifying a correlation component relating to leakage and detecting the leakage without being affected by a temperature change. According to the present invention, it is possible to provide a leakage inspection apparatus capable of accurately inspecting a large-capacity container requiring a long time for inspection by performing temperature compensation in parallel during leakage inspection.

[0025] Further, according to the invention of claim 7, the volume of the container and the correlation calculated by the calculation means are calculated. By using the values of the components, it is possible to calculate the magnitude of the leakage of the container force, and particularly to the container when the container is pressurized or depressurized as in the invention according to claim 8. By measuring the flow rate of the fluid flowing into or out of the vessel and calculating the volume of the vessel, it is possible to automatically calculate the amount of leakage.

 [0026] According to the ninth aspect of the present invention, similarly to the fourth aspect of the invention, at the time of pressurization or depressurization, a substance having the same composition as the substance contained in the container whose leakage is to be inspected or the same substance Supply or absorption of some substances contained in the container, it is possible to prevent a substance different from the substance contained in the container from being taken into the container, and to replace the substance contained in the container after the inspection. The work can be omitted, and a leak inspection can be performed without releasing flammable gas or toxic gas into the atmosphere.

 [0027] Further, according to the invention of claim 10, as in the invention of claim 5, the substance collected from the container whose leakage is to be inspected or a part of the substance is adsorbed to the adsorbent material at the time of suction. Thereby, the suction operation can be performed efficiently, and the adsorbed substance can be stably held. Further, at the time of supply, the above-mentioned adsorbed substance is released from the adsorbed material to thereby release a substance having the same component as the substance contained in the container to be inspected for leakage or a partial substance contained in the component. There is no need to arrange other containers such as gas cylinders to supply. Alternatively, at the time of the supply, if a substance of the same component as the substance contained in the container to be inspected for leakage from another container or a part of the substance contained in the component is supplied, the adsorbed substance is used. Special means for release can be omitted.

 Brief Description of Drawings

FIG. 1 is a view showing a model of a leak state in a container.

 FIG. 2 is a diagram expressing, in a block diagram, a relational expression relating to a state of leakage in a container.

 FIG. 3 is a schematic view of a leakage inspection device according to the present invention.

 FIG. 4 is a schematic diagram of a leakage inspection device using a time change in pressure.

 FIG. 5 is a block diagram of a control circuit of the leakage inspection device using a time change in pressure.

 FIG. 6 is a diagram showing a leakage inspection situation in the case where there is no temperature fluctuation and no leakage.

 FIG. 7 is a diagram showing a leak inspection situation when there is no temperature fluctuation and there is a leak.

FIG. 8 is a diagram showing a leak inspection situation in a case where there is a temperature fluctuation and no leakage. FIG. 9 is a diagram showing a leak inspection situation when there is a temperature fluctuation and a leak.

 FIG. 10 is a diagram showing a leak inspection situation using a one-way pump when there is no temperature fluctuation and there is a leak.

 FIG. 11 is a diagram showing a leak inspection situation using irregular pressurization and depressurization when there is no temperature fluctuation and there is a leak.

FIG. 12 is a schematic diagram of a leak inspection device using an adsorbent material.

 FIG. 13 is a schematic diagram of a leak inspection device using an adsorbent material and a gas cylinder.

Explanation of symbols

1 container

 2 Pressure sensor

 3 piston

 4 cylinder

 5 Linear Actuator

 6 oscillator

 7 90 ° phase shifter

 8 Correlator

 11 Connection

 12 Detection hose

 13, 17 Norbu

 14 Pressure sensor

 15, 34, 38 Electric pump

 16 Controller

 20 AZD converter

 21 dPZdt calculator

 22 Synchronous detection circuit

 23 Smoothing circuit

 24 Pressurization control section

25 Reference signal generator 26 Leak judgment unit

 27 Leakage amount calculation unit

 31, 36 adsorption vessel

 32 Adsorption material

 43 Supply container

 BEST MODE FOR CARRYING OUT THE INVENTION

[0030] The basic concept of the present invention will be described below.

 FIG. 1 is a model of a leak state of a container such as a pipe, which is a target of the leak inspection method according to the present invention.

 The presence of gas in the container, and the state of the gas, indicate the gas pressure P, the gas temperature T, the mass of the gas in the container Μ, the average molecular weight m of the gas, the average density p of the gas, Suppose that the volume V of

 0

 When the container is in a leak state, let Q be the volume flow rate of gas leaking from the container. Also, assume that the mass flow rate of gas flowing into the container when the gas in the container is pressurized and depressurized by a pump or the like to the container to be inspected is G.

[0031] The state equation relating to the gas in the container is given by the following equation (1).

 PV = MRT / m (1)

 0

 Considering the time change of the state quantity of the gas in the container, the following equation (2) is obtained by time-differentiating both sides of the equation (1).

 V -dP / dt = RT / m -dM / dt + MR / mdT / dt

 o

 [0032] The initial state in the container is as follows when the initial pressure P, the initial mass M, and the initial temperature T are:

 0 0 0

 It is expressed by the state equation (3).

 P V = M RT / (3)

 0 0 0 0

 Assuming that the changes in the mass M of the gas in the container and the temperature T of the gas in the vessel due to leakage are both small, and neglecting the second-order minute term, Equation (2) can be calculated using Equation (3) above. The following equation is obtained.

 V -dP / dt = P V / M -dM / dt + P V / T -dT / dt

 0 0 0 0 0 0 0

By dividing both sides of the above equation by PV, the following equation (4) is obtained. 1 / P -dP / dt = l / M -dM / dt + l / T -dT / dt (4)

 0 0 0

 Now, assuming that gas is leaking from a part of the container (volume flow rate Q) together with gas flowing into the container (inflow mass flow rate G) by the pressurizing step to the container, Is represented by the following equation (5). Where p is the average density of the gas.

 dM / dt =-Q + G (5)

 On the other hand, the volume flow rate Q of the container force is proportional to the pressure difference between the inside and outside when the gas density and pressure change in the container where leakage is small is small, so it is expressed as the following equation (6). Is done.

 Q = (P-P) -k = p (t) -k (6)

 A 1 1

 Where P is the atmospheric pressure, p (t) = P—P is the pressure difference between the inside and outside of the vessel, and k is the magnitude of the leak

 A A 1

 It is a coefficient.

 [0034] The above equations (5) and (6) are substituted into the above equation (4), and P is multiplied on both sides to further increase the energy.

 0

Using the fact that the average density of the body is _p = M / V, the following equation (7) is obtained.

 0 0

 dp (t) / dt = -k-p (t) + P / M -G + P / T -dT / dt

 0 0 0 0

 … · · (7)

 Where k = P / V-k, and the time change of the pressure P is the pressure difference p (t) between the inside and outside of the container.

 0 0 1

 Is used.

 From the above equation (7), the time variation of the pressure in the container depends on the term (1 k′p (t)) related to leakage from the container and the mass flow rate G of the gas flowing into the container. Item P / M and in container

 0 0

 It is understood that it consists of the term P / Ύ'dTZdt that depends on the temperature change of the gas

 0 0 And the leak inspection of the container can be said to be the operation of specifying the size of the term relating to the leak, that is, the coefficient k (or k), in the equation (7) describing the container model.

 FIG. 2 is a block diagram of the above equation (7).

 As is clear from the block diagram, a leaking vessel inputs P / M'G, which is proportional to the inflow mass flow rate of the gas added to the vessel, and outputs the pressure difference p (t) between the inside and outside of the vessel.

 0 0

 It is described as a first-order lag system with a feedback loop proportional to the magnitude of the leak. Then, the component P / T'dTZdt related to the temperature change of the gas is added to the input of this system.

 0 0

The noise is superimposed on the noise. Therefore, the problem of leak detection is formulated as a system identification problem in which the coefficient k of the system in FIG. 2 into which the unknown disturbance P 0 / T 0 'dTZdt is mixed is estimated from the input and the output. However, the nature of the temperature disturbance dTZdt, which is an unknown disturbance, can be estimated to some extent from the experimental data and the thermal dynamics of the container.

 [0037] Since P / M · G, which is an input to the system, can be set freely,

 0 0

 If G is set so as to be uncorrelated with the temperature fluctuation dTZdt, and the pressure difference p (t) is observed and the correlation method is used, the coefficient k that is not affected by the temperature fluctuation, that is, the magnitude of the leakage Can be identified.

 Input signal P / M when using the correlation method

 The condition of 0 0 'G is as follows.

 (a) The signal must be uncorrelated with the temperature fluctuation dTZdt.

 (b) The inside of the container can be regarded as an isothermal change. Specifically, the dominant frequency of the input signal is sufficiently low compared to the reciprocal of the thermal time constant of the container!

 (c) The dominant frequency of the input signal is sufficiently higher than the reciprocal of the leak time constant (lZk) of the container.

 By using the following equation (1), which is an equation derived from the correlation function, it is also possible to use the correlation between the time integral P / M · Gdt of the input and the time derivative dp (t) Zdt of the output. it can

0 0

 . P ZM · ί Gdt is the amount of pressurization or decompression when gas flows into or out of the container.

0 0

 While dp (t) Zdt is the time variation of the pressure in the vessel.

[0038] [number 1]

)--0 (τ)

FIG. 3 shows an example of the leak inspection method according to the present invention.

A vessel 1 such as a pipe is connected to a pressurizing or depressurizing means comprising a cylinder 4 and a piston 3 for increasing or decreasing pressure. The pressurizing / depressurizing means is not limited to the shape as shown in FIG. 3, and an electric pump as described later can be used. Further, the pressurizing means and the depressurizing means can be constituted by separate members. In order to measure the internal pressure of container 1, The pressure sensor 2 is connected in the middle of the pipe connecting the means.

[0040] A linear actuator 5 for reciprocating the piston is connected to the piston 3 of the caro pressure reducing means. The actuator is configured such that the movable portion moves up and down by a moving distance corresponding to the input signal from the oscillator 6, and as a result, the piston 3 connected to the movable portion performs reciprocating motion.

 Now, when an input signal of sin cot is applied to the actuator 5 from the oscillator, the piston 3 reciprocates at X sin cot. Where X is the vibration related to the reciprocation of the piston.

 0 0

 Indicates the width value. Here, the angular frequency ω of the reciprocating motion is selected so as to satisfy the following condition.

 • Temperature component dTZdt does not include the frequency component of angular frequency ω.

 • The angular frequency is low enough that the temperature change in the container can be regarded as an isothermal change. • ω is a sufficiently high angular frequency compared to the cutoff frequency (k) of the container due to leakage.

By setting the initial pressure 大 to the atmospheric pressure Ρ and reciprocating the piston, the inside of the container 1 becomes sin

 0 A

 The pressure is increased or decreased in a predetermined time sequence defined by cot. The mass flow rate G corresponding to the equation (7) is expressed as (0 ω χ Scos co t = M / V · ω χ Scos co

 0 0 0 0 t. The pressure in the container 1 is detected by the pressure sensor 2. The detected pressure detection signal

P (t), and the pressure detection signal is input to the correlator 8.

 On the other hand, the input signal of the oscillator power is output by the 90 ° phase shifter 7 as a reference signal cos cot whose phase is shifted by 90 ° from the input signal, and is input to the correlator 8.

[0042] The pressure P (t) in the container is equal to the starting force of the piston in a steady state after a sufficient time has passed.

And the following equation (2).

[0043] [Equation 2]

P _Q +

When the correlation between the pressure detection signal P (t) and the reference signal cos cot is calculated in the correlator 8, the constant pressure P

The correlation with 0 is zero, and the temperature fluctuation dTZdt does not include the component of the angular frequency ω, so the correlation with the third term is also zero. After all, the output of correlator 8 is Correlation with the second term P / V · ω χ S 'k / (k ² + ω ² ). Here, 0)

 0 0 0

 Considering that it is large, the output of the correlator is approximated as Ρ / V · χS'kZo. This out

 0 0 0

 From the force, the coefficient k representing the magnitude of the leak can be determined.

 In the embodiment of FIG. 3, a sine wave signal is used as the inflow mass flow rate G of the gas that determines the input signal, and its angular frequency is selected to a value that the temperature fluctuation dTZdt does not include as a frequency component. In. As the inflow mass flow rate G, any analog signal can be used as long as there is no correlation with temperature fluctuation, and an irregular signal such as white noise is used.

 In addition, there is a method of repeating a regular pressurizing and depressurizing step as illustrated in FIGS. 6-9 to simplify the apparatus. Furthermore, there is a method of correlating the reference signal in phase with the time integration of the inflow mass flow rate G and the time change of the pressure in the container in consideration of ease of calculation. When the regular pressurization and depressurization steps are repeated, a synchronous detection circuit can be used as a specific arithmetic device for calculating the correlation. Further, as illustrated in FIG. 10, there are a method of repeating pressurizing or depressurizing the container and opening to the atmospheric pressure, and a method of using an irregular pressurizing / depressurizing step illustrated in FIG.

 Next, as a preferred embodiment of the present invention, a method of calculating the correlation with the time change of the pressure in the container will be described, taking a leak inspection device of a gas pipe as an example.

 FIG. 4 is a schematic diagram showing the concept of the mechanical configuration of the leakage inspection device of the present invention. Inside the leak inspection device, an electric pump 15 for supplying gas such as air to the container to be inspected or discharging gas from the container, a pressure sensor 14 for inspecting the pressure inside the container, As shown in Fig. 4, a knob or check valve 13 for controlling the amount of gas supplied to the container or the amount of gas discharged from the container 13 and a valve 17 for equalizing the pressure in the container to the atmospheric pressure are provided as shown in Fig. 4. Are connected to each other with a simple connection structure.

 A detection hose 12 extends from the pressure measuring device, and as shown in a connection section 11, at the time of inspection, the detection hose 12 is connected to a discharge port such as a gas tap provided in a container such as a gas pipe to be inspected. Connect the tip.

In addition, when conducting a pipe inspection on the capacity of a gas pipe of a general household, it is more convenient to carry and handle by incorporating the electric pump 15 into a leak inspection device. Shi However, when inspecting a container with a large capacity, such as a pipe in a factory plant, the supply amount of air and the like into the container increases. Are desirably connectable to each other.

 [0047] Not limited to the configuration of FIG. 4 described above, for example, a substance contained in a container, which is an object to be inspected, may be released into the atmosphere, or a substance different from the substance contained in the container may be contained in the container. It is also possible to adopt a configuration as shown in FIG. 12 or FIG. 13 in order to prevent being taken in.

 In FIG. 12, an adsorbent material 32 stored in an adsorption container 31 is used, and is constituted by a flow path of a pressurized system via a pump 15 and a valve B, and a flow path of a depressurized system via a valve A. During depressurization, the pump 15 is stopped, the valve B is closed, and the knob A is opened, so that the gas in the test object is adsorbed by the adsorbent material 31 and the pressure in the test object can be reduced. It becomes. In particular, in order to assist the action of the adsorbent material 32, it is preferable that the inside of the adsorption container 31 be held in advance in a reduced pressure state in comparison with the test object. If necessary, a pump (not shown) can be installed on the detection target side of Knob A to collect gas to be adsorbed on the adsorption material side. Known materials such as activated carbon can be used as such an adsorption material.

When pressurizing, by closing valve A and opening valve B, the pump 15 allows the gas adsorbed by the adsorbent material 32 to be sent out to the test object by the operation of the pump 15. You. If necessary, the adsorbent can be heated to release the adsorbed gas and the conditions can be set to increase the gas delivery efficiency.

 Next, in FIG. 13, when depressurizing the inside of the inspection object, an adsorbing material that adsorbs the gas in the inspection object is used as in FIG. During depressurization, the valve C is opened, and the valve D is closed to perform the depressurizing operation. During pressurization, the knurl C is closed and the knurl D is opened, so that the supply container (gas cylinder) is a gas supply means. From 43, supply gas into the inspection target. The pressure in the supply container 43 is set in advance to be higher than the pressure in the inspection target.

In FIG. 12 and FIG. 13, since it is necessary to appropriately control the pressurized and depressurized states, it is particularly necessary to appropriately control the opening and closing of the valves A to D. The inspection target and In order to adjust the flow rate between the related equipment such as the gas and the adsorption container and the gas cylinder, it is also possible to provide a flow rate adjusting means such as an orifice in a pipe connecting the respective equipments. Further, in FIG. 13, the gas adsorbed by the adsorbent material 32 can be returned to the gas cylinder 43 by adjusting the connection portion 11 and the valves C and D. If necessary, a pressurizing device such as a pump can be installed in front of the valves C and D.

The controller 16 performs drive control of the electric pump 15, opening and closing control of the valves 13 and 17, detection of a pressure signal of the pressure sensor 14, and the like. Then, under the control of the controller 16, various inspections such as a leakage inspection of the container, a measurement of the capacity in the container, and a measurement of a leakage amount in the container, which will be described below, are performed.

Next, a main leak inspection circuit incorporated in the controller 16 will be described.

 As shown in FIG. 5, the leakage inspection circuit includes an AZD conversion unit 20, a dPZdt calculation unit 21, a synchronous detection circuit unit 22, a smoothing circuit unit 23, a compression / decompression control unit 24 serving as a compression / decompression control unit, and a reference signal generation unit. 25, a leakage determination unit 26, and a leakage amount calculation unit 27.

 The pressurizing / depressurizing control unit 24 instructs the drive control of the electric pump 15 and the opening / closing control of the valves 13 and 17 in a predetermined time sequence according to a control program in which various leak inspection modes are stored and shown.

[0053] The detection signal from the pressure sensor 14 is input to the AZD conversion unit 20, and converts an analog signal, which is a detection signal, into a digital signal. Then, based on the digital signal, dPZdt, which is the time variation of the pressure P, is calculated by the dPZdt calculation unit 21.

 If it can be assumed that the time constant related to the leakage of the container force is sufficiently large compared to the pressure measurement time, the pressure measurement at multiple points {t, P (t)} (i = 0, 1, N), and dPZdt can be obtained by linear approximation using the least squares method or the like.

 In addition, in order to compensate for the variation in the amount of pressurization or depressurization at the end of the pressurization / depressurization process, the value of dPZdt calculated using the signal of the pressure sensor force is specified by the initial value of the pressurization or depressurization. In some cases, it is used to calculate later.

Next, the reference signal generation section 25 generates a reference signal based on a signal generated in connection with the compression / decompression control procedure of the compression / decompression control section 24.

The reference signal can correspond to various kinds of signals. Imming is a time excluding the transient response time during the pressurization / decompression step and immediately after the step, such as adiabatic compression or adiabatic expansion. In general, during the pressurization / decompression process and during the transient response time immediately after the process, the pressure changes greatly regardless of the leakage, which causes noise in the leakage inspection.

This period is set so that the reference signal indicates a value of 0. If the amplitude of the pressure increase / decrease amount is too small compared to the initial pressure P, which is large, the pressure change during pressurization and the decrease

 0

 There is a difference in pressure change during pressure. In this case, for example, a signal of α and 1 may be used as a reference signal by using a coefficient α for compensating for the above difference between 1 and 1 signals.

Next, a component of the measured pressure change signal that has a correlation with the reference signal synchronized with the time series of the pressurization and decompression process is calculated. Specifically, the synchronous detection circuit unit 22 extracts the calculated value of dPZdt at a time when the reference signal has a value other than 0 based on the reference signal, and adds the calculated value of the reference signal to the extracted dPZdt value. The value is multiplied.

 Next, the signal extracted and calculated by the synchronous detection circuit section is smoothed by the smoothing circuit section 23 so as to calculate a time average value which is the magnitude of the above-described component. Perform processing.

 The synchronous detection circuit unit 22 and the smoothing circuit unit 23 are integrated, and the dPZ dt value (for example, the average value obtained by linear approximation) of the section indicated by the reference signal is weighted by ± 1 of the reference signal and averaged. , Can also be calculated digitally.

 In addition, when calculating dPZdt, synchronous detection, and smoothing, a circuit that converts an analog signal of 14 pressure sensors into an analog signal state by an analog arithmetic circuit is not limited to the calculation using the digital signal described above. It may be.

[0056] The leak determination unit 26 determines that there is no leakage when the signal power from the smoothing circuit unit 23 is 0 (or within a predetermined error range from 0), and otherwise determines that there is leakage. In addition, in the leak amount calculation unit, since the signal value from the smoothing circuit unit 23 and the pressure change amount per unit time are in a proportional relationship, the leak amount is calculated for each leak inspection device or each leak inspection mode. The amount of leakage from the container is calculated by multiplying the set proportional constant by the signal value from the smoothing circuit unit 23 and integrating the calculated and input container capacity of the test object separately. I do. As a method for automatically measuring the capacity of a container, as described in the previous patent application (Japanese Patent Application Laid-Open No. 2003-227773), when a container is pressurized or depressurized, it flows into or out of the container. It is also possible to calculate from the equation of state of the gas based on the flow rate of the fluid and the amount of pressure change in the vessel at that time.

 Next, the leak inspection method of the present invention will be specifically described with reference to each measurement example of the leak inspection device shown in FIGS. 6 to 9.

 FIG. 6 shows an embodiment in which a forward / reverse rotation pump is used as the electric pump 15 to increase / decrease the pressure in the container of the test object.

 In particular, Fig. 6 shows the temperature fluctuation in the container and the situation without leakage.

 FIG. 6 (a) shows the timing at which the inside of the container is pressurized, depressurized, pressurized and decompressed, and closed by the drive control of the electric pump and the opening and closing control of the valves 13 and 17.

 FIG. 6 (b) is a graph showing the output of the detection signal of the pressure sensor 14 as a change in the pressure P in the container by the pressurization / decompression control shown in FIG. 6 (a). In the pressurizing step, the pressure P increases, and in the depressurizing step, the pressure P decreases. In addition, a transient response due to adiabatic compression immediately after the end of the pressurizing step and a transient response due to adiabatic expansion immediately after the depressurizing step occur.When the temperature of the gas in the container reaches an equilibrium state, the pressure P shows a constant state. .

 FIG. 6 (c) is a graph obtained by time-differentiating a graph of the pressure P, which is a detection signal of the pressure sensor 14, in the dPZdt calculation unit. During the pressurizing step, the depressurizing step, and the transient response period, a value other than 0 is shown. However, if there is no temperature change and no leakage, dPZdt = 0 in the equilibrium state.

 FIG. 6D is a graph showing the state of the reference signal from the reference signal generation unit 25. The reference signal corresponds to the pressurization step, At the timing excluding the depressurization process and the transient response period, 1 is generated to indicate the equilibrium state after the depressurization process, and 1 is generated to indicate the equilibrium state after the depressurization process, so that they have the same pulse width. Let me.

FIG. 6E is a graph showing an output signal from the synchronous detection circuit unit 22. The value of dPZdt when the reference signal indicates a value other than 0 is extracted, and the value of the extracted dPZdt is extracted. Is calculated by multiplying by the reference signal value and output. In the case of FIG. 6, when the reference signal (d) has a value other than 0, the time-varying value (c) of the pressure P is 0. Value.

FIG. 6 (f) is a graph showing an output signal in the smoothing circuit unit 23. In the smoothing circuit section 23, the value is 0 in order to time-average the output signal (f) of the synchronous detection circuit section 22.

 Since it is the output value power ^ from the smoothing circuit unit 23, the leakage determination unit 26 determines that "no leakage". Also, the leak amount calculation unit 27 uses a value obtained by multiplying the output value of the smoothing circuit unit 23 by a constant as the pressure change amount (time change of the pressure). As a result, the pressure change amount becomes 0, and the pressure change amount becomes zero. Multiplied by the volume of the container is also calculated as zero.

[0063] Fig. 7 shows a measurement situation in the case where only a leak whose temperature changes in the container is generated.

 FIG. 7 (a) shows the timing when the inside of the container is pressurized, depressurized, pressurized and depressurized, and closed as in FIG. 6 (a).

 Fig. 7 (b) shows the change in the pressure P in the container, as in Fig. 6 (b). Shows a gradual increase after the process

FIG. 7 (c) shows the output of the dPZdt calculation unit 21 similarly to FIG. 6 (c), and the pressure drop due to the leakage after the pressurization step becomes a negative value, The pressure rise due to the leakage of is calculated and output as a positive value.

 FIG. 7D is a graph showing the state of the reference signal from the reference signal generator 25, which is generated similarly to FIG. 6D.

 FIG. 7 (e) shows a signal obtained by extracting the output signal (c) of the dPZdt calculating unit 21 based on the reference signal (d) and multiplying the extracted value by the reference signal, similarly to FIG. 6 (e). It is.

 As shown in the graph of Fig. 7 (e), the pressure drop due to leakage after the pressurization step is displayed as a positive constant value as a result of multiplying the negative dPZdt value by 1 of the reference signal, and The rise in pressure due to leakage of the pressure is displayed as a positive constant value as a result of multiplying the positive dPZdt value by 1 of the reference signal.

FIG. 7 (f) is a graph showing the output signal of the smoothing circuit unit 23, similarly to FIG. 6 (f). In order to average the graph of FIG. 7 (e) over time, a positive constant value is shown.

 Since the output value from the smoothing circuit unit 23 is a positive constant value, the leakage determination unit 26 determines that “leakage is present”. The leak amount calculation unit 27 uses a value obtained by multiplying the output value of the smoothing circuit unit 23 by a predetermined constant as the pressure change amount (time change of pressure), and separately inputs the calculated pressure change amount. Alternatively, the amount of leakage is calculated and output by multiplying the calculated capacity of the container.

FIG. 8 shows a measurement situation when there is a temperature change (temperature rise) in the container and no leakage.

 FIG. 8 (a) shows the timing when the inside of the container is pressurized, depressurized, pressurized and depressurized, and closed as in FIG. 6 (a).

 Fig. 8 (b) shows the change in the pressure P in the container, as in Fig. 6 (b). It gradually increases after the process.

 FIG. 8 (c) shows the output of the dPZdt calculation unit 21 as in FIG. 6 (c). The pressure rise due to the subsequent temperature rise is calculated and output as a positive value.

 FIG. 8D is a graph showing the state of the reference signal from the reference signal generator 25, which is generated similarly to FIG. 6D.

 FIG. 8 (e) is a diagram obtained by extracting the output signal (c) of the dPZdt calculating unit 11 based on the reference signal (d) and multiplying the extracted value by the reference signal, similarly to FIG. 6 (e). It is.

 As shown in the graph of Fig. 8 (e), the pressure rise due to the temperature rise after the pressurization step is displayed as a negative constant value as a result of multiplying the positive dPZdt value by 1 of the reference signal, Subsequent pressure rise due to temperature rise is displayed as a positive constant value as a result of multiplying the positive dPZdt value by a reference signal of 1.

FIG. 8 (f) is a graph showing the output signal of the smoothing circuit unit 23 as in FIG. 6 (f). In order to average the time of the graph of FIG. Show.

Since it is the output value power ^ from the smoothing circuit unit 23, the leakage determination unit 26 determines that "no leakage". The leak amount calculation unit 27 calculates the pressure change (pressure change over time) as Since a value obtained by multiplying the output value of the smoothing circuit unit 23 by a constant is used, the pressure change amount becomes 0 as a result, and the leakage amount obtained by multiplying the pressure change amount by the capacity of the container is also calculated as 0.

FIG. 9 shows a measurement state in a case where there is a temperature change (temperature rise) in the container and there is a leak.

 FIG. 9 (a) shows the timing when the inside of the container is pressurized, decompressed, pressurized and depressurized, and closed as in FIG. 6 (a).

 Fig. 9 (b) shows the change in the pressure P in the container, as in Fig. 6 (b) .After the pressurization step, the pressure rise due to temperature rise and the pressure drop due to leakage overlap. Here, a constant level (no pressure change) is shown here. After the depressurization step, both the pressure rise due to the temperature rise and the pressure rise due to the leakage occur, so the pressure rise due to only the leakage in Fig. 7 (b) and the temperature rise only in Fig. 8 (b) Shows a steep pressure rise than the pressure rise caused by the influence of.

FIG. 9 (c) shows the output of the dPZdt calculation unit 21 as in FIG. 6 (c), where the level of the pressure after the pressurizing step is 0, and The steep pressure rise is calculated and output as a positive value larger than the values in Fig. 7 (c) and Fig. 8 (c)! RU

 FIG. 9D is a graph showing the state of the reference signal from the reference signal generator 25, which is generated similarly to FIG. 6D.

 FIG. 9 (e) shows a signal obtained by extracting the output signal (c) of the dPZdt calculating unit 21 based on the reference signal (d) and multiplying the extracted value by the reference signal, similarly to FIG. 6 (e). It is.

 As shown by the graph in Fig. 9 (e), the leveling-off state of the pressure change after the pressurizing step is displayed as a value 0 as a result of multiplying the dPZ dt value of 0 by 1 of the reference signal, The pressure rise is displayed as a positive constant value as a result of multiplying the positive dPZdt value by 1 of the reference signal.

 FIG. 9 (f) is a graph showing the output signal of the smoothing circuit unit 23 as in FIG. 6 (f). The time constant of the graph of FIG. Is shown.

Since the output value from the smoothing circuit unit 23 is a positive constant value, the leakage determination unit 26 determines that “leakage is present”. Further, the leak amount calculation unit 27 calculates the pressure change amount (time change of the pressure) using a value obtained by multiplying the output value of the smoothing circuit unit 23 by a predetermined constant. The leak amount is calculated and output by multiplying the pressure change amount thus obtained by a separately input or calculated capacity of the container.

 The method of repeating the regular pressurizing and depressurizing steps to correlate the time change of the pressure in the container with the reference signal has been described in detail. For simplicity, the explanation assumes that temperature fluctuations increase linearly, but this assumption is not necessary in theory. What is necessary for the leak test of the present invention is that the temperature fluctuation is uncorrelated with the reference signal, that is, it becomes 0 when the pressure change caused by the temperature fluctuation is multiplied by the reference signal and averaged.

 As a modification of the configuration in FIG. 4, there is a method in which the electric pump 15 uses a one-way pump that can only pressurize or depressurize, and the configuration of the device is simplified. In this method, as shown in Fig. 10, the container is repeatedly pressurized or depressurized and opened to the atmospheric pressure alternately and regularly, and the leak is inspected by correlating the time change of the container pressure with the reference signal. I do.

 As is evident from this configuration example, it is not necessary for the amount of pressure applied to the container to fluctuate by the same pressure above and below the atmospheric pressure.It is not necessary to switch between any two pressures. It is possible to separate the pressure change caused by the temperature change from the pressure change caused by the temperature change.

 FIG. 10 shows a measurement situation in the case where there is only a leak in which the temperature inside the container changes.

 FIG. 10 shows an example in which the pressurizing step and the valve opening step are alternately repeated. As shown in the change of the pressure P in the container in FIG. When a transient response occurs due to a transfer response or adiabatic expansion immediately after the valve opening process, and the gas temperature in the container reaches an equilibrium state, the pressure P gradually decreases due to leakage. In general, the pressure drop due to the leakage after the pressurizing step and the pressure drop after the valve opening step have a larger slope in the pressure drop after the pressurizing step.

Further, as shown in FIG. 10 (d), the reference signal corresponds to the pressurization and depressurization control by the pressurization and depressurization control unit 24 at the timing excluding the pressurization step, the valve opening step and the transient response period. 1 is generated to indicate the equilibrium state after the process, and 1 is generated to indicate the equilibrium state after the pressure is reduced by the valve opening process so that they have the same pulse width. Except for the above, how to read the graphs in Fig. 10 is the same as in Fig. 6-9, so the description is omitted.

[0074] In the case of performing regular pressurization and decompression, the fact that the temperature fluctuation does not have the same frequency component as the reference signal! This is a condition for separating leaks and detecting leaks. In general, it can be expected that this condition will be satisfied if the period of regular pressurization is appropriately selected. However, there may be a special case in which the reference signal and the temperature fluctuation cannot be made uncorrelated if regular pressurization is performed.

 In such a case, a binary irregular signal may be used as the time series of the pressure increase / decrease. FIG. 11 illustrates a case where the compression / decompression pattern is modulated by an M-sequence signal that is a binary pseudo-random signal. As the reference signal, a signal obtained by removing the period of the transient response based on the M-sequence signal used for modulation is used. If a sufficiently high-order M-sequence signal is used, there is no correlation with temperature fluctuations existing in the natural world. It becomes possible.

 FIG. 11 shows a measurement state in a case where there is only a leak that changes in temperature inside the container.

 In FIG. 11, as shown in FIG. 11 (b), the pressurizing step and the depressurizing step are executed in an irregular time sequence.

 Further, as shown in FIG. 11 (d), the reference signal includes the calorie at the timing excluding the pressurizing step, the depressurizing step, and the transient response period in accordance with the pressurizing and depressurizing control by the pressurizing and depressurizing control unit 24. Generate 1 to indicate the equilibrium state after the pressure reduction step, and 1 to indicate the equilibrium state after the pressure reduction step so that they have the same pulse width! /

 Except for the above, how to read each graph in FIG. 11 is the same as in FIG. 6-10, and therefore, the description is omitted.

[0076] The present invention is not limited to the above description. As described in Patent Document 1, storage means for storing various measurement mode programs related to leak inspection and storage means for storing measurement data It goes without saying that a known technique in the relevant field can be added, such as a technique for providing a display, a display means such as a liquid crystal, and a technique relating to an input means such as a KEY board. Industrial applicability

 According to the present invention, the leak of a container such as a pipe can be efficiently inspected, and the effect of the temperature change in the container can be removed simultaneously with the leak detection, thereby accurately detecting the leak even in a large-capacity container. It is possible to provide a leak inspection method and device capable of performing the above. Further, according to the present invention, it is possible to incorporate the pressurizing and depressurizing steps in an arbitrary time series, and the step of returning the pressure in the container to the atmospheric pressure as in the earlier application is not required, so that a large-capacity flammable Effective leak inspection can also be performed on toxic gas piping and toxic gas containers.

Claims

The scope of the claims

 [1] A pressurizing and depressurizing step of pressurizing or depressurizing a container to be inspected for leakage in accordance with a predetermined time sequence, and a pressure measuring step of measuring a pressure change in the container,

 Calculating a correlation between the signal measured in the pressure measurement step and a reference signal corresponding to the time sequence,

 A leakage inspection method comprising detecting leakage of the container based on the correlation.

 [2] The leak inspection method according to claim 1, wherein the signal measured in the pressure measurement step is a time change signal of pressure.

[3] In the leakage inspection method according to claim 1 or 2, the reference signal is configured to exclude a signal in a transient response period during a pressurizing / depressurizing step and immediately after the step from the correlation calculation. A leak inspection method characterized by the following.

[4] In the leak inspection method according to any one of claims 1 to 3, the pressurizing / depressurizing step includes a substance having the same component as a substance contained in a container to be inspected for leakage, or a partial substance contained in the component. A leakage inspection method characterized by supplying or sucking air.

[5] According to the leak inspection method according to claim 4, the suction causes the substance or a part of the substance collected from the container to be inspected for leakage to be adsorbed on an adsorbent material, and the supply includes: The adsorbed substance is released from the adsorbent material, or a substance of the same component as the substance contained in the container to be inspected for leakage from another container or a part of the substance contained in the component is supplied. A leak inspection method characterized by the following.

[6] pressurizing or depressurizing means for pressurizing or depressurizing a container to be inspected for leakage,

 Pressure measuring means for measuring a pressure change in the container,

 Pressurization control means for controlling the pressurization and decompression means for performing the pressurization and decompression of the container in accordance with a predetermined time sequence;

 Calculating means for calculating a correlation between the signal obtained by the pressure measuring means and a reference signal corresponding to the time sequence,

 A leak inspection device characterized by detecting a leak in the container based on the correlation calculated by the calculating means.

[7] The leak inspection apparatus according to claim 6, wherein the volume of the container to be inspected and the arithmetic means A means for calculating the magnitude of leakage of the container based on the correlation calculated by the method.

 [8] The leak inspection apparatus according to claim 7, wherein the volume of the container measures a flow rate of a fluid flowing into or out of the container when the container is pressurized or depressurized, and the inside of the container. A leak inspection device characterized by being calculated based on a value measured by a pressure measuring means for measuring a pressure change.

 [9] In the leak inspection apparatus according to claim 6, the pressurizing / depressurizing means is supplied with a substance of the same component as the substance component contained in the container to be inspected for leakage or a part of substances contained in the component. A leak inspection device, characterized in that it is connected to a supply means for performing suction or a suction means for performing suction.

 [10] In the leak inspection apparatus according to claim 9, the suction means has a container to be inspected for leaks, and has an adsorbent material for adsorbing the recovered substance or a part of the substance, and the supply means includes: The substance adsorbed by the adsorbent material is released or supplied from another container that contains a substance of the same component as the substance component contained in the container whose leakage is to be inspected or a part of the substance contained in the component. A leak inspection device, characterized in that: