Detection device and detection method

Abstract

To provide a detection device and a detection method which can detect which of inner and outer pipes comprising a double-structure pipe is damaged more easily than before.SOLUTION: A detection device 1 detects damage of a pipe 20 having: an inner pipe 21 through which a reducing substance passes; and an outer pipe 22 having a substantially vacuum-state region 32 between the inner pipe 21 and itself. The detection device 1 includes: a gas sensor 2 provided between the inner pipe 21 and the outer pipe 22; and a determination part 11 for determining which of the inner pipe 21 and the outer pipe 22 is damaged on the basis of output of the gas sensor 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a detection device and a detection method for detecting breakage in a double-structure pipe. [Background technology]

[0002] The use of a double-wall vacuum insulated pipe has been proposed as a piping system for transporting and supplying liquefied gases such as liquid nitrogen, liquid helium, liquid hydrogen, and liquefied natural gas. This insulated pipe has a structure in which an inner pipe through which the liquefied gas passes is covered by an outer pipe via a vacuum layer. This provides high thermal insulation and effectively suppresses the temperature rise of the low-temperature liquefied gas flowing inside the inner pipe.

[0003] If such a double-walled vacuum insulated pipe is damaged, it is necessary to confirm whether the inner pipe or the outer pipe has been damaged. For example, Patent Document 1 describes a method for detecting damage to a vacuum insulated pipe for liquefied gas, which includes "monitoring the pressure inside the inner pipe with an inner pipe pressure measuring device that measures the pressure inside the inner pipe, monitoring whether an outer pipe pressure relief device provided on the outer pipe has been activated within a predetermined time range when an unusual change in the value measured by the inner pipe pressure measuring device is detected, detecting the release of a detection target gas with a gas detection device when the outer pipe pressure relief device has been activated, and determining whether the inner pipe or the outer pipe has been damaged based on the measurement value of the inner pipe pressure measuring device and the presence or absence of the release of the detection target gas detected by the gas detection device." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-101284 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a pressure sensor is placed inside the inner pipe as in the method described in Patent Document 1, an outer pipe pressure relief device must also be provided in order to detect whether the inner pipe or the outer pipe has been damaged.

[0006] An object of the present invention is to provide a detection device and a detection method that can more easily detect whether an inner pipe or an outer pipe constituting a double-structure piping has been damaged. [Means for solving the problem]

[0007] [1] A detection device according to one aspect of the present invention is a detection device for detecting damage to a pipe having an inner pipe through which a reducing substance passes and an outer pipe having an area in a substantially vacuum state between the inner pipe and the outer pipe, and is equipped with a gas sensor arranged between the inner pipe and the outer pipe, and a determination unit that determines whether the inner pipe or the outer pipe has been damaged based on the output of the gas sensor.

[0008] [2] In the detection device of the above [1], the gas sensor may be any one of a solid electrolyte sensor, a constant potential electric field sensor, and a non-dispersive infrared sensor.

[0009] [3] The detection device of the above [1] or [2] may further include a pressure sensor disposed between the inner pipe and the outer pipe.

[0010] [4] In any of the detection devices [1] to [3] above, the gas sensor may be a concentration cell type oxygen sensor, and the determination unit may distinguish and determine whether the outer tube or the inner tube is damaged when the output of the oxygen sensor fluctuates compared to the output in the approximately vacuum state.

[0011] [5] In any one of the detection devices [1] to [3] above, the gas sensor may be a limiting current type oxygen sensor, and the determination unit may distinguish and determine whether the outer tube or the inner tube has been damaged when the output of the oxygen sensor fluctuates compared to the output in the nearly vacuum state.

[0012] [6] In any one of the detection devices [1] to [5] above, the reducing substance passing through the inside of the inner tube may be at least one selected from hydrogen, ammonia, methane, carbon monoxide, ethane, butane, propane, isobutane, methanol, and ethanol.

[0013] [7] Another aspect of the present invention is a detection method for detecting breakage in a pipe having an inner pipe through which a reducing substance passes and an outer pipe having a region in a substantially vacuum state between the inner pipe and the outer pipe, and the detection method determines whether the inner pipe or the outer pipe has broken based on the output of a gas sensor disposed between the inner pipe and the outer pipe. [Effects of the Invention]

[0014] According to one aspect of the present invention, a detection device can more easily detect whether an inner pipe or an outer pipe constituting a double-structure piping has been damaged. Also, according to another aspect of the present invention, a detection method can more easily detect whether an inner pipe or an outer pipe constituting a double-structure piping has been damaged. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a schematic diagram illustrating a general configuration of a detection device attached to a vacuum insulated pipe in one embodiment. [Figure 2] 1 is a cross-sectional view showing an example of an internal configuration of an oxygen sensor provided in a detection device according to a first embodiment. [Figure 3] 3 is a graph showing an example of a sensor output of the oxygen sensor shown in FIG. 2. [Figure 4] 6 is a graph showing the change in output of the oxygen sensor and the change in pressure in the vacuum region when the inner pipe is broken in one embodiment. [Figure 5] 6 is a graph showing the change in output of the oxygen sensor and the change in pressure in the vacuum region when the outer tube is broken in one embodiment. [Figure 6] 5 is a schematic view showing a case where an outer tube is broken in the first embodiment. FIG. [Figure 7] 5 is a schematic view showing a case where an inner tube is broken in the first embodiment. FIG. [Figure 8] 6 is a graph showing an example of a sensor output of an oxygen sensor provided in the detection device according to the second embodiment. [Figure 9] 10 is a graph showing the change in output of the oxygen sensor and the change in pressure in the vacuum region when the inner pipe is broken in the second embodiment. [Figure 10] 10 is a graph showing the change in output of the oxygen sensor and the change in pressure in the vacuum region when the outer tube is broken in the second embodiment. [Figure 11] FIG. 10 is a schematic view showing a case where the outer tube is broken in the second embodiment. [Figure 12] FIG. 10 is a schematic view showing a case where the inner tube is broken in the second embodiment. [Figure 13] FIG. 1 is a schematic diagram showing the configuration of a test device used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed description thereof will not be repeated.

[0017] In this embodiment, a detection device 1 for detecting breakage in a double-walled pipe for transporting or supplying a reducing substance will be described as an example. Here, a reducing substance refers to a substance that has reducing properties or a substance that is easily oxidized. In this specification, the category of reducing substances includes hydrogen, ammonia, methane, carbon monoxide, ethane, butane, propane, isobutane, methanol, and ethanol. The reducing substance may be in either a liquid or gaseous state, or may be in both a liquid and a gaseous state.

[0018] (Schematic configuration of the detection device) The detection device 1 is used to detect damage to a vacuum insulated pipe used in, for example, a transfer facility for liquid hydrogen, liquid ammonia, etc. Fig. 1 shows a schematic configuration of the detection device 1 attached to a vacuum insulated pipe 20.

[0019] The vacuum insulated piping 20 is a double-structure piping having an inner pipe 21 and an outer pipe 22. A reducing substance to be transferred (e.g., hydrogen, ammonia, etc.) passes through a space 31 inside the inner pipe 21. The outer pipe 22 is provided so as to cover the inner pipe 21. The space between the inner pipe 21 and the outer pipe 22 is in a vacuum state (i.e., a vacuum region 32). The configuration of the vacuum insulated piping 20 can be, for example, the configuration of a conventionally known double-structure piping for transferring liquefied gas.

[0020] The detection device 1 includes a gas sensor 2, a pressure sensor 3, and a control unit 10. The gas sensor 2 is disposed between an inner tube 21 and an outer tube 22. More specifically, a sensing unit of the gas sensor 2 is disposed in a vacuum region 32 between the inner tube 21 and the outer tube 22. This enables the gas sensor 2 to detect the concentration of a specific gas (e.g., oxygen gas) in the vacuum region 32.

[0021] The pressure sensor 3 is disposed between the inner tube 21 and the outer tube 22. More specifically, a sensing portion of the pressure sensor 3 is disposed in the vacuum region 32 between the inner tube 21 and the outer tube 22. This allows the pressure sensor 3 to detect the pressure of the gas in the vacuum region 32. In one example, the pressure sensor 3 is disposed near the gas sensor 2.

[0022] For example, a conventionally known air pressure sensor can be used as the pressure sensor 3. In another embodiment, the detection device 1 may not have a pressure sensor.

[0023] The control unit 10 is connected to and controls each unit (e.g., gas sensor 2, pressure sensor 3, etc.) in the detection device 1. The control unit 10 includes a determination unit 11 that determines whether the inner pipe 21 or the outer pipe 22 is damaged based on the outputs of the gas sensor 2 and the pressure sensor 3. The control unit 10 also includes a memory (not shown), a timer (not shown), etc.

[0024] For example, a solid electrolyte sensor, a constant potential electric field sensor, or a non-dispersive infrared sensor can be used as the gas sensor 2. More specifically, the zirconia solid electrolyte sensor (see page 13 of the reference), constant potential electric field sensor (see page 10 of the reference), or non-dispersive infrared sensor (see page 14 of the reference) described in the following references can be used. Reference: "RIKEN Sensor Technology Introduction" (RIKEN Keiki Co., Ltd. PC9-0315-200110)

[0025] This gas sensor 2 is placed in the vacuum region 32 of the vacuum insulated piping 20, and by observing the change in the output of the gas sensor 2, it is possible to determine whether the inner pipe 21 or the outer pipe 22 has been damaged. That is, the detection method according to one embodiment determines whether the inner pipe 21 or the outer pipe 22 has been damaged based on the output of the gas sensor 2 placed between the inner pipe 21 and the outer pipe 22.

[0026] The following describes the configuration of the detection device when the detection device 1 is equipped with different types of gas sensors 2 (specifically, oxygen sensors 2A and 2B), and a method for detecting breakage in a pipe.

[0027] (First embodiment) In the first embodiment, the gas sensor 2 is described as a concentration cell type oxygen sensor. A concentration cell type oxygen sensor is a sensor classified as a zirconia solid electrolyte type sensor. Since the gas sensor 2 of the detection device 1 is a concentration cell type oxygen sensor, it is possible to measure the oxygen concentration in the vacuum region 32.

[0028] 2 shows the internal configuration of a concentration cell-type oxygen sensor 2A (hereinafter simply referred to as oxygen sensor 2A). The oxygen sensor 2A mainly comprises a sensor element 101, a heater 102, a sensor cover 103, a ventilation cover 104, wiring 105, and a sensor control unit 112.

[0029] The sensor element 101 outputs an electromotive force (0 ←→ 1 V) corresponding to the oxygen concentration in the space to be detected (in this embodiment, the vacuum region 32). The sensor element 101 has, for example, a solid electrolyte body containing zirconia and a pair of electrodes arranged with the solid electrolyte body sandwiched therebetween. FIG. 2 shows an example of a configuration in which the oxygen sensor 2A has a cylindrical sensor element 101 with a bottom, but in other embodiments, the sensor element may be plate-shaped.

[0030] The heater 102 heats the sensor element 101. The sensor cover 103 is provided to cover the sensor element 101 and protects the sensor element 101 from floating particles in the space to be detected.

[0031] The ventilation cover 104 supplies the reference atmosphere to the inside of the sensor element 101. The wiring 105 connects the electrodes in the sensor element 101 to the sensor control unit 112.

[0032] The sensor control unit 112 is disposed, for example, in the control unit 10. The sensor control unit 112 detects the oxygen concentration in the detection target space (i.e., the vacuum region 32) based on the voltage (electromotive force) generated between the electrodes included in the sensor element 101.

[0033] An example of the sensor output of the oxygen sensor 2A is shown in Figure 3. As shown in Figure 3, when the oxygen concentration in the detection space is low (left side in Figure 3), the oxygen sensor 2A produces a high output (high voltage), and when the oxygen concentration in the detection space is high (right side in Figure 3), the oxygen sensor 2A produces a low output (low voltage).

[0034] By disposing the sensing portion of the oxygen sensor 2A within the vacuum region 32, it is possible to detect the oxygen concentration within the vacuum region 32. When the inner tube 21 and the outer tube 22 are not damaged (i.e., when they are normal), the oxygen partial pressure in the vacuum region 32 is low, and the output of the oxygen sensor 2A is also low. Specifically, for example, at the degree of vacuum in the test conducted in this embodiment, the output was approximately 0.2 V (200 mV) (see Figures 4 and 5, etc.).

[0035] In this state, if the sensing portion of the oxygen sensor 2A is exposed to a reducing gas (e.g., hydrogen gas, ammonia gas, etc.), the remaining oxygen in the sensing portion of the oxygen sensor 2A will burn, causing the oxygen partial pressure to drop sharply, and the output of the oxygen sensor 2A to rise sharply. That is, if the inner tube 21 breaks (without breaking the outer tube 22) and reducing substances flow into the vacuum region 32, which is in a substantially vacuum state, the reducing substances will vaporize, exposing the sensing portion of the oxygen sensor 2A to the reducing gas, and the output of the oxygen sensor 2A will rise sharply. FIG. 4 shows an example of the change in output of the oxygen sensor 2A in this case. In FIG. 4, the pressure change in the vacuum region 32 is also indicated by a dashed line.

[0036] 4 is a graph showing the results of a test conducted using the test device 200 to confirm the behavior of the oxygen sensor 2A in an example described later. Fig. 4 shows the change in output of the oxygen sensor 2A when hydrogen gas is injected. In Fig. 4, A indicates the timing when evacuation began, B indicates the timing when evacuation ended, and C indicates the timing when hydrogen gas was injected.

[0037] On the other hand, if the outer tube 22 is damaged (without damaging the inner tube 21), atmospheric air will flow into the vacuum region 32, which is in a substantially vacuum state. In this case, the output of the oxygen sensor 2A will decrease due to the influence of oxygen contained in the atmospheric air. Figure 5 shows an example of the change in output of the oxygen sensor 2A in this case. In Figure 5, the change in pressure within the vacuum region 32 is also shown by a dashed line.

[0038] Fig. 5 is a graph showing the results of a test conducted using test device 200 to confirm the behavior of oxygen sensor 2A in an example described later. Fig. 5 shows the change in output of oxygen sensor 2A when it is opened to the atmosphere. In Fig. 5, A indicates the timing when evacuation begins, B indicates the timing when evacuation ends, and C indicates the timing when it is opened to the atmosphere.

[0039] From the above, when the gas sensor 2 is the oxygen sensor 2A, the determination unit 11 determines that the outer pipe 22 is damaged when the output of the oxygen sensor 2A drops compared to the normal output (i.e., the output when the vacuum region 32 is in a substantially vacuum state) (see FIG. 5). Also, the determination unit 11 determines that the inner pipe 21 is damaged when the output of the oxygen sensor 2A rises compared to the normal output (i.e., the output when the vacuum region 32 is in a substantially vacuum state) (see FIG. 4).

[0040] Note that the opposite determination result to the above may be obtained by changing the sensor output setting in the control unit 10. That is, when the output of the gas sensor 2 drops compared to the normal output, it may be determined that the inner pipe 21 has been damaged, and when the output increases compared to the normal output, it may be determined that the outer pipe 22 has been damaged.

[0041] As described above, when the output of the oxygen sensor 2A fluctuates compared to the output in a substantially vacuum state, the judgment unit 11 can distinguish and judge whether the outer tube 22 or the inner tube 21 has been damaged.

[0042] The detection device 1 may determine that damage has occurred in either the inner pipe 21 or the outer pipe 22 using only the oxygen sensor 2A, but may also make a similar determination using the detection results of the pressure sensor 3 in addition to the oxygen sensor 2A.

[0043] When making a judgment using the oxygen sensor 2A and the pressure sensor 3, the judgment unit 11 judges that the outer tube 22 is damaged when the output of the oxygen sensor 2A decreases compared to the output under normal conditions (i.e., when the vehicle is in a substantially vacuum state) and the output of the pressure sensor 3 increases compared to the output under normal conditions (i.e., when the vehicle is in a substantially vacuum state) (see Figure 6).

[0044] Furthermore, the judgment unit 11 judges that the inner pipe 21 is damaged when the output of the oxygen sensor 2A increases compared to the output in the normal state (i.e., in an approximately vacuum state) and the output of the pressure sensor 3 increases compared to the output in the normal state (i.e., in an approximately vacuum state) (see Figure 7).

[0045] Furthermore, if the output of the pressure sensor 3 is the same as the output during normal operation (i.e., when the pressure sensor 3 is in a substantially vacuum state) or is lower than the output during normal operation, it is predicted that the degree of vacuum within the vacuum region 32 is high. Therefore, in this case, it is highly likely that neither the inner pipe 21 nor the outer pipe 22 is damaged. Therefore, in this case, the determination unit 11 determines that no damage has occurred in the piping, regardless of any change in the output of the oxygen sensor 2A.

[0046] The output of oxygen sensor 2A can also change due to fluctuations in the degree of vacuum within vacuum region 32. Therefore, by having determination unit 11 also take into account the detection result of pressure sensor 3, it can more reliably determine that damage has occurred in either inner pipe 21 or outer pipe 22. This reduces the possibility that determination unit 11 will erroneously detect a pipe breakage due to a change in the output of oxygen sensor 2A caused by fluctuations in the degree of vacuum within vacuum region 32.

[0047] As described above, the detection device 1 according to this embodiment detects breakage in a vacuum insulated pipe 20 that includes an inner pipe 21 through which a reducing substance passes and an outer pipe 22 that has a region 32 in a substantially vacuum state between the inner pipe 21 and the outer pipe 22. The detection device 1 includes a gas sensor (specifically, an oxygen sensor 2A) that is arranged between the inner pipe 21 and the outer pipe 22, and a determination unit 11 that determines whether the inner pipe 21 or the outer pipe 22 has broken based on the output of the gas sensor.

[0048] The detection method according to this embodiment determines whether the inner pipe 21 or the outer pipe 22 is damaged based on the output of a gas sensor (specifically, the oxygen sensor 2A) disposed between the inner pipe 21 and the outer pipe 22. This detection method can be performed using, for example, the detection device 1.

[0049] As described above, the oxygen sensor 2A disposed between the inner pipe 21 and the outer pipe 22 exhibits different output changes when the inner pipe 21 is damaged and when the outer pipe 22 is damaged. Therefore, by disposing the oxygen sensor 2A in the vacuum region 32 between the inner pipe 21 and the outer pipe 22 and having the determination unit 11 determine whether the inner pipe 21 or the outer pipe 22 is damaged based on the change in the output of the oxygen sensor 2A, it is possible to distinguish between damage to the inner pipe and damage to the outer pipe using the oxygen sensor alone. Therefore, the detection device and detection method according to this embodiment make it easier to detect whether the inner pipe or the outer pipe constituting the double-structure piping has been damaged.

[0050] Furthermore, the detection device 1 may further include a pressure sensor 3 in addition to the oxygen sensor 2A. This makes it possible to more reliably determine whether damage has occurred in either the inner pipe 21 or the outer pipe 22.

[0051] (Second embodiment) In the second embodiment, an example will be described in which the gas sensor 2 is a limiting current type oxygen sensor. A limiting current type oxygen sensor is a sensor classified as a zirconia solid electrolyte type sensor. Since the gas sensor 2 of the detection device 1 is a limiting current type oxygen sensor, it is possible to measure the oxygen concentration in the vacuum region 32.

[0052] An example of the sensor output of a limiting current type oxygen sensor 2B (hereinafter simply referred to as oxygen sensor 2B) is shown in Fig. 8. As shown in Fig. 8, when the oxygen concentration in the detection space is low (left side in Fig. 8), the oxygen sensor 2B produces a low output (low current), and when the oxygen concentration in the detection space is high (right side in Fig. 8), the oxygen sensor 2B produces a high output (high current).

[0053] By disposing the sensing portion of oxygen sensor 2B within vacuum region 32, it is possible to detect the oxygen concentration within vacuum region 32. When inner pipe 21 and outer pipe 22 are not damaged (i.e., when they are operating normally), the oxygen partial pressure in vacuum region 32 is low, and the output of oxygen sensor 2B is zero (0 mA) or a value nearly equal to zero (see Figures 9 and 10, etc.).

[0054] In this state, if the sensing portion of oxygen sensor 2B is exposed to a reducing gas (e.g., hydrogen gas, ammonia gas, etc.), the remaining oxygen in the sensing portion of oxygen sensor 2B will burn, causing a sudden drop in the oxygen partial pressure and a sudden drop in the output of oxygen sensor 2B. That is, if inner tube 21 is damaged (without damaging outer tube 22) and reducing substances flow into vacuum region 32, which is in a substantially vacuum state, the reducing substances will vaporize, exposing the sensing portion of oxygen sensor 2B to reducing gas, and the output of oxygen sensor 2B will suddenly drop. FIG. 9 shows an example of the change in output of oxygen sensor 2B in this case. In FIG. 9, the pressure change in vacuum region 32 is also indicated by a dashed line.

[0055] Fig. 9 is a graph showing the results of calculations of the behavior of oxygen sensor 2B when a test similar to that in the examples described below is performed using oxygen sensor 2B. Fig. 9 shows the change in output of oxygen sensor 2B when hydrogen gas is injected. In Fig. 9, A indicates the timing when evacuation begins, B indicates the timing when evacuation ends, and C indicates the timing when hydrogen gas is injected.

[0056] On the other hand, if the outer tube 22 is damaged (without damaging the inner tube 21), atmospheric air will flow into the vacuum region 32, which is in a substantially vacuum state. In this case, the output of the oxygen sensor 2B will decrease due to the influence of oxygen contained in the atmospheric air. Figure 10 shows an example of the change in output of the oxygen sensor 2B in this case. In Figure 10, the pressure change in the vacuum region 32 is also shown by a dashed line.

[0057] Fig. 10 is a graph showing the results of calculations of the behavior of oxygen sensor 2B when a test similar to that of the example described below is performed using oxygen sensor 2B. Fig. 10 shows the change in output of oxygen sensor 2B when it is opened to the atmosphere. In Fig. 10, A indicates the timing when evacuation begins, B indicates the timing when evacuation ends, and C indicates the timing when it is opened to the atmosphere.

[0058] From the above, when the gas sensor 2 is the oxygen sensor 2B, the determination unit 11 determines that the outer pipe 22 is damaged when the output of the oxygen sensor 2B increases compared to the normal output (i.e., the output when the vacuum region 32 is in a substantially vacuum state) (see FIG. 10). Also, the determination unit 11 determines that the inner pipe 21 is damaged when the output of the oxygen sensor 2B decreases compared to the normal output (i.e., the output when the vacuum region 32 is in a substantially vacuum state) (see FIG. 9).

[0059] Note that the opposite determination result to the above may be obtained by changing the sensor output setting in the control unit 10. That is, when the output of the gas sensor 2 increases compared to the normal output, it may be determined that the inner pipe 21 has been damaged, and when the output decreases compared to the normal output, it may be determined that the outer pipe 22 has been damaged.

[0060] As described above, when the output of the oxygen sensor 2B fluctuates compared to the output in a substantially vacuum state, the judgment unit 11 can distinguish and judge whether the outer pipe 22 or the inner pipe 21 has been damaged.

[0061] The detection device 1 may determine that damage has occurred in either the inner pipe 21 or the outer pipe 22 using only the oxygen sensor 2B, but may also make a similar determination using the detection results of the pressure sensor 3 in addition to the oxygen sensor 2B.

[0062] When making a judgment using the oxygen sensor 2B and the pressure sensor 3, the judgment unit 11 judges that the outer tube 22 is damaged when the output of the oxygen sensor 2B increases compared to the output under normal conditions (i.e., when the vehicle is in a substantially vacuum state) and when the output of the pressure sensor 3 increases compared to the output under normal conditions (i.e., when the vehicle is in a substantially vacuum state) (see Figures 10 and 11).

[0063] Furthermore, the judgment unit 11 judges that the inner pipe 21 is damaged when the output of the oxygen sensor 2B decreases compared to the output in the normal state (i.e., in an approximately vacuum state) and the output of the pressure sensor 3 increases compared to the output in the normal state (i.e., in an approximately vacuum state) (see Figures 9 and 12).

[0064] Furthermore, if the output of pressure sensor 3 is the same as the output during normal operation (i.e., when there is a substantial vacuum), or is lower than the output during normal operation, it is predicted that the degree of vacuum within vacuum region 32 is high. Therefore, in this case, it is highly likely that neither inner pipe 21 nor outer pipe 22 is damaged. Therefore, in this case, determination unit 11 determines that there is no damage to the piping, regardless of any change in the output of oxygen sensor 2B.

[0065] The output of oxygen sensor 2B can also change due to fluctuations in the degree of vacuum within vacuum region 32. Therefore, by having determination unit 11 also take into account the detection result of pressure sensor 3, it is possible to more reliably determine that damage has occurred in either inner pipe 21 or outer pipe 22. This reduces the possibility that determination unit 11 will erroneously detect a pipe breakage due to a change in the output of oxygen sensor 2B caused by fluctuations in the degree of vacuum within vacuum region 32.

[0066] (Example) In this example, the change in output of the oxygen sensor 2A was measured using a test device 200. Fig. 13 shows a schematic configuration of the test device 200 used in this test.

[0067] The test apparatus 200 includes a hydrogen gas supply unit 201, a mass flow controller (MFC) 202, a vacuum pump 203, a vacuum gauge 204, a measurement chamber 205, a connection unit 206, and three valves V1, V2, and V3. These components are arranged on multiple pipes (e.g., P1, P2, P3, etc.). The pipes P1, P2, and P3 are connected to each other via a single connection unit 206.

[0068] Within the path of pipe P1, a hydrogen gas supply unit 201, a flow rate control device (MFC) 202, and a valve V1 are arranged in this order from the end farthest from the connecting unit 206. Within the path of pipe P2, a vacuum pump 203 and a valve V1 are arranged in this order from the end farthest from the connecting unit 206. Within the path of pipe P3, a valve V3, a measurement chamber 205, and a vacuum gauge 204 are arranged in this order from the end farthest from the connecting unit 206. The end of pipe P3 is an exhaust port E.

[0069] The sensing portion of the oxygen sensor 2A is disposed inside the measurement chamber 205. This allows the oxygen sensor 2A to measure the oxygen concentration inside the measurement chamber 205.

[0070] In the test device 200 having the above-described configuration, it is possible to create a state similar to that which occurs when both the inner pipe and the outer pipe of a heat-insulating double-structured pipe are broken.

[0071] Specifically, with valves V1 and V3 closed, the vacuum pump 203 is operated to create a substantial vacuum inside the system of the testing device 200, and then when valve V1 is opened, hydrogen gas, which is a type of reducing gas, flows into the measurement chamber 205. This state is similar to the state in which the inner pipe 21 of the vacuum insulated piping 20 is damaged. Therefore, this case is called an assumed inner pipe leak case.

[0072] Furthermore, when the vacuum pump 203 is operated with the valves V1 and V3 closed to create a substantial vacuum inside the system of the testing device 200, and then the valve V3 is opened, air flows into the measurement chamber 205 from the exhaust port E. This state is the same as when the outer pipe 22 of the vacuum insulated piping 20 is damaged. Therefore, this case is called the assumed outer pipe leak case.

[0073] In this example, an inner pipe leak case and an outer pipe leak case were created in the testing device 200, and the change in output of the oxygen sensor 2A was measured. The results are shown in Figures 4 and 5. Figure 4 shows the change in output of the oxygen sensor 2A in the inner pipe leak case, and Figure 5 shows the change in output of the oxygen sensor 2A in the outer pipe leak case.

[0074] As shown in Figure 4, in the case of an assumed inner pipe leak, the output of oxygen sensor 2A rose sharply at timing C when hydrogen gas was injected. On the other hand, as shown in Figure 5, in the case of an assumed outer pipe leak, the output of oxygen sensor 2A fell to almost zero (0 mV) at timing C when the sensor was opened to the atmosphere. In this way, it was confirmed that the output of oxygen sensor 2A showed different changes in the cases of an assumed inner pipe leak and an assumed outer pipe leak.

[0075] 4 and 5, the pressure change within the system of the test device 200 during each test is shown by a dashed line. Comparing Figures 4 and 5, it can be seen that the pressure change within the test device 200 is roughly the same in both the case of the inner pipe leak assumption and the case of the outer pipe leak assumption.

[0076] From this, it can be seen that in a configuration in which a reducing substance such as hydrogen gas passes through the inner tube, if only a pressure sensor is placed in the vacuum region between the inner tube and the outer tube, the behavior of the sensor will be almost the same in either the leakage of a reducing substance from the inner tube or the leakage of air from the outer tube, making it impossible to distinguish between damage to the inner tube and damage to the outer tube.

[0077] In contrast, in a configuration in which a reducing substance such as hydrogen gas passes through the inner tube, when the oxygen sensor 2A is placed in the vacuum region between the inner tube and the outer tube, it has been confirmed that the oxygen sensor alone can distinguish between damage to the inner tube and damage to the outer tube.

[0078] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. Furthermore, configurations obtained by combining the configurations of the various embodiments described in this specification are also included in the scope of the present invention. [Explanation of symbols]

[0079] 1:Detection device 2: Gas sensor 2A: Concentration cell type oxygen sensor (gas sensor) 2B: Limiting current type oxygen sensor (gas sensor) 3: Pressure sensor 10: Control unit 11: Judgment section 20: Vacuum insulated piping (piping) 21: Inner tube 22:Outer tube 32: Vacuum area

Claims

1. A detection device for detecting breakage in a pipe having an inner pipe through which a reducing substance passes and an outer pipe having a region in a substantially vacuum state between the inner pipe and an outer pipe, a gas sensor disposed between the inner tube and the outer tube; a determination unit that determines whether the inner pipe or the outer pipe is damaged based on an output of the gas sensor; A detection device comprising:

2. The gas sensor is any one of a solid electrolyte sensor, a constant potential field sensor, and a non-dispersive infrared sensor. The detection device of claim 1 .

3. Further comprising a pressure sensor disposed between the inner tube and the outer tube. The detection device of claim 1 .

4. the gas sensor is a concentration cell type oxygen sensor, The determination unit When the output of the oxygen sensor fluctuates compared with the output in the substantially vacuum state, it is determined whether the outer tube or the inner tube is damaged. The detection device according to any one of claims 1 to 3.

5. the gas sensor is a limiting current type oxygen sensor, The determination unit When the output of the oxygen sensor fluctuates compared with the output in the substantially vacuum state, it is determined whether the outer tube or the inner tube is damaged. The detection device according to any one of claims 1 to 3.

6. the reducing substance passing through the inside of the inner tube is at least one selected from hydrogen, ammonia, methane, carbon monoxide, ethane, butane, propane, isobutane, methanol, and ethanol; The detection device according to any one of claims 1 to 3.

7. A detection method for detecting a break in a pipe having an inner pipe through which a reducing substance passes and an outer pipe having a region in a substantially vacuum state between the inner pipe and an outer pipe, the method comprising: A detection method for determining whether the inner pipe or the outer pipe is damaged based on an output of a gas sensor disposed between the inner pipe and the outer pipe.

Images