Hydrogen concentration measuring element and hydrogen concentration measuring device

Abstract

The present invention relates, in one embodiment, to a hydrogen concentration measuring element (100, 100a) comprising: a sensing portion (110) including a metal wire (111) whose electrical resistance varies according to hydrogen absorption and a protective coating layer (112) having hydrogen permeability and covering the metal wire (111); and a longitudinally extending pillar-shaped mounting portion (120). The sensing portion (110) is wound around the mounting portion (120) between the two end portions (131, 132). The mounting portion (120) has lateral faces (120a, 120b) having a groove portion (121) in which the sensing portion (110) is housed.In the groove portion (121), a plurality of supports (121b) projecting into the groove portion (121) to support the sensing portion (110) are formed; and between the plurality of supports (121b), the sensing portion (110) is arranged linearly without being in contact with any surface of the groove portion (121). Figure for the abbreviation: Fig. 1.

Description

Title of the invention: Hydrogen concentration measuring element and Hydrogen concentration measuring device FIELD OF THE INVENTION

[0001] Embodiments of the present invention relate to a hydrogen concentration measuring element and a hydrogen concentration measuring device.

[0002] CONTEXT OF THE INVENTION

[0003] Conventional hydrogen concentration measuring devices include devices using measuring methods such as a catalytic combustion method and a semiconductor method.

[0004] Technologies for the catalytic combustion type include that which uses combustion heat on a catalyst that promotes the combustion of hydrogen and oxygen, and detects the hydrogen concentration on the basis of a change in resistance value appearing in a resistance measuring device (thermistor) when the temperature is changed by the combustion heat. Technologies for the semiconductor type include that which uses a change in electrical resistance value by using a change in carrier density appearing on the surface of a semiconductor, such as tin oxide, due to the adsorption of a reducing gas.

[0005] Furthermore, hydrogen concentration measurement technologies for nuclear power plants include a technology utilizing the volume expansion of palladium due to its absorption of hydrogen, a technology utilizing a change in scattered light when light at a specific wavelength penetrates through an optical fiber, and a technology utilizing an electrical resistance value of a hydrogen-absorbing material.

[0006] A hydrogen concentration measuring device based on the electrical resistance value of the hydrogen absorbing material comprises: a hydrogen concentration measuring element including a sensing part in which a metal wire acting as the hydrogen absorbing material is covered with a protective coating layer having hydrogen permeability and a fixing part around which the sensing part is wound; and a calculator which calculates a hydrogen concentration from the electrical resistance value in the hydrogen concentration measuring element.

[0007] PRIOR ART DOCUMENT

[0008] PATENT DOCUMENT

[0009] Patent Document 1: Japanese Patent No. 6,585,463. Summary of the invention

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] In the above-described hydrogen concentration measuring device, the metal wire expands and contracts by thermal expansion. Therefore, when the temperature rises and falls during transport tests of the hydrogen concentration measuring element or during use thereof, friction occurs at contact portions between the protective coating layer covering the metal wire and peripheral members, resulting in the peeling off of the protective coating layer. In particular, in the case where the detection portion is wound around the fixing portion, a portion in the detection portion that contacts and rubs against the fixing portion changes randomly. Therefore, a peeled-off area of ​​the film becomes larger when the temperature rises and falls repeatedly, resulting in the deterioration of hydrogen detection performance.Another problem is that quality variation between products is increasing.

[0012] An object of the present invention is to provide a hydrogen concentration measuring element and a hydrogen concentration measuring device with which deterioration of hydrogen detection performance can be prevented.

[0013] MEANS TO SOLVE THE PROBLEM

[0014] According to one aspect of the present invention, there is provided a hydrogen concentration measuring element comprising: a detection part comprising a metal wire whose electrical resistance value varies depending on the absorption of hydrogen and a protective coating layer having hydrogen permeability and covering the metal wire; and a pillar-shaped fixing part which extends in a longitudinal direction, at two locations of which in the longitudinal direction terminal parts for connecting to an external part are attached, and around which the detection part is wound between the two terminal parts, characterized in that: the fixing part has a side face having a groove part where the detection part is accommodated; in the groove part, a plurality of supports projecting into the groove part for supporting the detection part are formed;and between the plurality of supports, the detection portion is linearly arranged without being in contact with a surface of the groove portion. Brief description of the drawings;

[0015] [Fig. 1] is a block diagram illustrating the configuration of a hydrogen concentration measuring device according to one embodiment.

[0016] [Fig.2] is a perspective view illustrating the configuration of a hydrogen concentration measuring element of the hydrogen concentration measuring device according to the embodiment.

[0017] [Fig. 3] is a sectional view illustrating the configuration of the hydrogen concentration measuring element of the hydrogen concentration measuring device according to the embodiment, viewed in the direction of arrow AA in [Fig. 2].

[0018] [Fig.4] is a sectional view illustrating the configuration of the hydrogen concentration measuring element of the hydrogen concentration measuring device according to the embodiment, viewed in the direction of arrow BB in [Fig.2].

[0019] [Fig.5] is a longitudinal sectional view illustrating the configuration of a detection portion in the hydrogen concentration measuring element of the hydrogen concentration measuring device according to the embodiment.

[0020] [Fig.6] is a sectional view illustrating the configuration of the detection portion in the hydrogen concentration measuring element of the hydrogen concentration measuring device according to the embodiment.

[0021] [Fig.7] is a conceptual perspective view for explaining a relationship between a groove portion and the detection portion in the hydrogen concentration measuring element of the hydrogen concentration measuring device according to the embodiment.

[0022] [Fig.8] is a conceptual perspective view for explaining a relationship between a groove portion and a detection portion in an example of modification of the hydrogen concentration measuring element of the hydrogen concentration measuring device according to the embodiment. DETAILED DESCRIPTION

[0023] A hydrogen concentration measuring device according to one embodiment of the present invention is described below with reference to the drawings. Herein, identical or similar parts are designated by common reference signs and redundant description thereof is omitted.

[0024] [Fig. 1] is a block diagram illustrating the configuration of the hydrogen concentration measuring device 10 according to the embodiment. [Fig.l] illustrates an example in which a measurement target of the hydrogen concentration measuring device 10 is an atmosphere in a nuclear reactor containment vessel 1 of nuclear reactor facilities (not shown). The nuclear reactor containment vessel 1 is a vessel for housing a nuclear reactor vessel (not shown). It should be noted that the measurement target of the hydrogen concentration measuring device 10 is not limited to the atmosphere in the nuclear reactor containment vessel 1 and may be other targets such as an atmosphere. mosphere whose hydrogen concentration is to be measured in, for example, hydrogen production plants or hydrogen supply plants.

[0025] The hydrogen concentration measuring device 10 comprises a hydrogen concentration measuring element 100, a resistor 31, connection lines 32 and an information processing unit 33.

[0026] The hydrogen concentration measuring element 100 comprises a metal wire 111 (see [Fig. 5]) having a hydrogen absorption capacity, its electrical resistance value varying according to the hydrogen absorption, and is a part for detecting hydrogen. The details of the hydrogen concentration measuring element 100 will be described later with reference to FIGS. 2 to 6.

[0027] The resistor 31 is connected to the wire 111 of the hydrogen concentration measuring element 100 by the connecting lines 32. The resistor 31 measures the electrical resistance value of the wire 111 when current is supplied to it. As the resistor 31, a known resistor is used, but in the case where the resistor 31 uses a measuring method other than a four-terminal method, such as, for example, a two-terminal method and a Wheatstone bridge, those suitable for the respective measuring methods are used.

[0028] The information processing unit 33 comprises a CPU (Central Processing Unit) and memories. The information processing unit 33 calculates the hydrogen concentration based on the electrical resistance value of the metal wire 111 measured by the resistor 31. That is, it utilizes a phenomenon that the electrical resistance value of the metal wire 111 increases when the metal wire 111 absorbs hydrogen. Based on a previously obtained hydrogen concentration-electrical resistance value correlation formula and the electrical resistance value of the metal wire 111 (see [Fig.5]) measured by the resistor 31, the information processing unit 33 sequentially calculates a hydrogen concentration.

[0029] [Fig. 2] is a perspective view illustrating the configuration of the hydrogen concentration measuring element 100 of the hydrogen concentration measuring device 10 according to the embodiment. [Fig. 3] is a sectional view illustrating the configuration of the hydrogen concentration measuring element 100 of the hydrogen concentration measuring device 10 according to the embodiment, viewed in the direction of arrow AA in [Fig. 2]. [Fig. 4] is a sectional view illustrating the configuration of the hydrogen concentration measuring element 100 of the hydrogen concentration measuring device 10 according to the embodiment, viewed in the direction of arrow BB in [Fig. 2].

[0030] The hydrogen concentration measuring element 100 comprises a portion of detection portion 110, a fixing portion 120 and end portions 131, 132. It should be noted that the detection portion 110 is indicated by the broken lines in [Fig. 2] for the convenience of illustration. Furthermore, in [Fig. 4], the illustration of the detection portion 110 is omitted for the convenience of illustration.

[0031] The sensing portion 110 is wire-shaped and wound around the fixing portion 120. The sensing portion 110 will be described in detail later with reference to FIGS. 5 and 6. The end portions 131, 132 serve to fix the sensing portion 110 to the fixing portion 120. The end portions 131, 132 are connected to the resistor 31 via the connecting lines 32 to also act as terminals used for measuring the electrical resistance value of the metal wire 111 (see [Fig. 5]) of the sensing portion 110. Although [Fig. 2] illustrates an example in which the end portions 131, 132 are placed on an outer surface of a side face of the fixing portion 120, the end portions 131, 132 may be placed on an inner surface of the side face of the fixing part 120.

[0032] The fixing portion 120 is made of an insulating material, such as a ceramic or a glass, and is used to fix (support) and insulate the detection portion 110. Although [Fig. 2] illustrates a case in which the fixing portion 120 is a prism with a square or oblong-rectangular cross-section, the fixing portion 120 may be plate-shaped as illustrated in a modification example described later or may have a cylindrical shape or a polygonal prismatic shape other than a quadrangular prismatic shape.

[0033] In the four side faces of the fixing part 120, a groove part 121 for winding the detection part 110 is spirally formed. The groove part 121 accommodates the detection part 110. In detail, in each of the four side faces of the fixing part 120, a plurality of unit grooves 122 are formed. The unit grooves 122 are each linearly formed. Furthermore, the unit grooves 122 each slope from a plane (xy plane) perpendicular to the longitudinal direction (z direction). The ends of the unit grooves 122 are each connected to one end of the unit groove formed on an adjacent side face. Accordingly, all of the unit grooves 122 are connected to form the single continuous groove portion 121 extending from the end portion 131 to the end portion 132.

[0034] As described above, the unit grooves 122 formed on each of the side faces slope from a direction of a line C of intersection between the side face where they are formed and a plane (plane parallel to the xy plane) perpendicular to the longitudinal direction (z direction) of the prismatic fixing part 120 by a predetermined angle in that side face. Therefore, the unit grooves 122 formed in the same lateral face are parallel to each other.

[0035] More specifically, when viewed from a side facing the end portion 131 and the end portion 132, the unit grooves 122a formed in a first side face 120a slope from a direction of an intersection line C1 in the first side face 120a in the z direction by an angle θ1. Furthermore, the unit grooves 122b formed in a second side face 120b slope from a direction of an intersection line C2 in the second side face 120b in the z direction by an angle θ2. The unit grooves 122 formed on the side faces facing the first side face 120a and the second side face 120b are also formed similarly to the unit grooves 122 formed on their facing surfaces. As a result, the groove portion 121 extending from the end portion 131 to the end portion 132 is formed.It should be noted that 01 and 02 do not need to be equal.

[0036] [Fig.3] is a sectional view of the groove portion 121 taken along a plane including the unit groove 122a formed in the first side face 120a and the unit groove 122b formed in the second side face 120b for connecting to the unit groove 122a. The hatched portion is a cross-section of the fixing portion 120. In the hatched portion, portions of the first side face side 120a and a portion of the second side face side 120b are a cross-section of the groove portion 121, i.e., the shape in the longitudinal direction of the bottom of the groove portion 121 is illustrated. As illustrated in [Fig. 3] and [Fig. 4], at the boundary portions between the unit grooves 122a and the unit grooves 122b, brackets 121b are formed, and between the adjacent brackets 121b, a cutout 121a is formed.In other words, in the groove portion 121, the cutouts 121a are formed such that the supports 121b protrude at connecting portions between the unit grooves 122, i.e., at the end positions of the unit grooves 122.

[0037] More specifically, the detection portion 110 has supported portions 110p in contact with the groove portion 121 at the supports 121b and non-contact portions 110q which are not in contact with the surfaces of the cutouts 121a of the groove portion 121.

[0038] Accordingly, the detection portion 110 is accommodated in the unit grooves 122 in the state illustrated in [Fig. 3] and [Fig. 4]. The plurality of supports 121b are provided in the groove portion 121, and the detection portion 110 is supported by the supports 121b at the locations where its direction changes. In addition, between the two adjacent supports 121b, the detection portion 110 is linearly disposed in the unit groove 122 such that it stretches without being in contact with the surface of the groove portion 121. That is, in each of the unit grooves 122, the detection portion 110 is arranged in the groove portion 121. detection 110 is supported only by the supports 121b located at both ends of the unit groove 122. The detection portion 110 is structured such that the major part thereof is thus not in contact with other parts including the groove portion 121.

[0039] Next, the detection portion 110 will be described in detail. [Fig. 5] is a longitudinal sectional view illustrating the configuration of the detection portion 110 in the hydrogen concentration measuring element 100 of the hydrogen concentration measuring device 10 according to the embodiment. [Fig. 6] is a sectional view illustrating the configuration of the detection portion 110 in the hydrogen concentration measuring element 100 of the hydrogen concentration measuring device 10 according to the embodiment.

[0040] The sensing portion 110 comprises the metal wire 111 and a protective coating layer 112 provided on the outer surface of the metal wire 111.

[0041] The metal wire 111 contains at least one of palladium and niobium and is capable of absorbing hydrogen. The diameter of the metal wire 111 capable of absorbing hydrogen is not limited and is preferably neither less than about 1 μm nor more than about 1000 μm. This is because the metal wire 111, if it has a diameter less than 1 μm, has a high risk of breaking due to its tensile force, and the metal wire 111, if it has a diameter greater than 1000 μm, has a low resistance value per unit length, leading to poorer hydrogen detection capability.

[0042] The protective coating layer 112 contains at least one of an oxide, a nitride, and a carbide of silicon or aluminum and is formed from an inorganic substance allowing hydrogen to selectively pass therethrough. The thickness of the protective coating layer 112 is preferably not less than 5 nm nor more than 200 nm. A protective coating layer 112 having a thickness of 5 nm or more has the remarkable effect of preventing the progress of a side reaction attributable to chemical species from an external gas layer, such as oxygen and iodine. A protective coating layer 112 having a thickness of 200 nm or less has excellent hydrogen permeability.

[0043] The detection portion 110 is herein formed by applying or vapor deposition of the protective coating layer 112 onto the metal wire 111 having hydrogen absorption capability. As the application or vapor deposition method, a conventional method is used, such as CVD (chemical vapor deposition), PVD (physical vapor deposition), a sol-gel method, or an impregnation method. Furthermore, it is generally known that the detection portion 110 formed by any of these methods is used after heat treatment at not less than 350°C and not more than 500°C.

[0044] [Fig. 7] is a conceptual perspective view for explaining a relationship between the groove portion 121 and the detection portion 110 in the hydrogen concentration measuring element 100 of the hydrogen concentration measuring device 10 according to the embodiment. [Fig. 7] conceptually illustrates states of the bottom of the groove portion 121 formed in the fixing portion 120 shown in [Fig. 2] and the detection portion 110 placed in the groove portion 121. As shown in [Fig. 7], the detection portion 110 extends from the end portion 131 to the end portion 132 while being linearly arranged between the adjacent supports 121b and changing direction at the supports 121b. Such a wiring state is expressed herein as a spiral.

[0045] As described above, the detection part 110 is supported by the fixing part 120 and is in contact with the fixing part 120 only at the supports 121b without being in contact with the fixing part 120 at other locations. This limits a range of an area where friction of the protective coating layer 112 occurs. Accordingly, it is possible to reduce deterioration of detection performance in the detection part 110 which is a hydrogen sensor element.

[0046] [Fig.8] is a conceptual perspective view for explaining a relationship between a groove portion 121 and a detection portion 110 in a hydrogen concentration measuring element 100a which is an example of modification of the hydrogen concentration measuring element 100 of the hydrogen concentration measuring device 10 according to the embodiment.

[0047] This modification example has supports 121b on both sides in the Y-axis direction, but has only one array of supports 121b in the x-axis direction. A possible structure of a fixing portion of the hydrogen concentration measuring element having such a groove portion 121 includes, for example, one whose vertical cross-section with respect to the longitudinal direction (z-axis direction) has an oblong rectangular shape that is long in the y-axis direction and short in the x-axis direction, as in the fixing portion 120 shown in [Fig. 8], or one, not shown, whose vertical cross-section with respect to the longitudinal direction has an elliptical shape having a major axis in the y-axis direction. That is, a hydrogen concentration measuring element 100a whose entire shape is substantially a plate shape can also be implemented.With the shape of a plate, this modification example can be placed even in a place where it is difficult to remember the thickness-direction dimension.

[0048] As described above, the path of the groove portion of the hydrogen concentration measuring element can be drawn in various forms.

[0049] According to the embodiment described above, due to the configuration in which the detection part 110 is in contact with the fixing part 120 only at the supports 121b without being in contact with the fixing part 120 at other positions, an area where the protective coating layer 112 rubs against the fixing part 120 is limited, thereby providing hydrogen concentration measuring elements 100, 100a and a hydrogen concentration measuring device 10 with which deterioration of hydrogen detection performance can be prevented.

[0050] OTHER EMBODIMENTS

[0051] Although certain embodiments have been described, these embodiments have been presented solely by way of example, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in various other forms; further, various omissions, substitutions, and modifications of the form of the embodiments described herein may be made without departing from the spirit of the inventions. The appended claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. List of reference signs

[0052] l...nuclear reactor containment vessel, 10...hydrogen concentration measuring device, 31...resistor, 32...connecting line, 33...information processing unit, 100, 100a...hydrogen concentration measuring element, 110...detection part, 110p...supported part, IlOq...non-contact part, 11 l...metal wire, 112...protective coating layer, 120...fixing part, 120a...first side face, 120b...second side face, 121...groove part, 121a...cutout, 121b...support, 122...unit groove, 131, 132...end part

Claims

Claims

1. A hydrogen concentration measuring element (100, 100a) comprising: a detection part (110) comprising a metal wire (111) whose electrical resistance value varies depending on hydrogen absorption and a protective coating layer (112) having hydrogen permeability and covering the metal wire (111); and a pillar-shaped fixing part (120) extending in a longitudinal direction, at two locations of which in the longitudinal direction end parts (131, 132) for connection to an external part are attached, and around which the detection part (110) is wound between the two end parts (131, 132), characterized in that: the fixing part (120) has side faces (120a, 120b) having a groove part (121) where the detection part (110) is accommodated;in the groove portion (121), a plurality of supports (121b) protruding into the groove portion (121) for supporting the detection portion (110) are formed; and between the plurality of supports (121b), the detection portion (110) is linearly arranged without being in contact with a surface of the groove portion (121).;

2. The hydrogen concentration measuring element (100, 100a) according to claim 1, wherein the fixing portion (120) has a polygonal prismatic shape having side faces (120a, 120b) having a plurality of unit grooves (122) connected together to form the groove portion (121).

3. The hydrogen concentration measuring element (100, 100a) according to claim 1 or claim 2, wherein: the groove portion (121) has a plurality of unit grooves (122) whose ends connect to each other; the plurality of unit grooves (122) are each formed linearly; and the supports (121b) are formed at locations where the ends of the unit grooves (122) connect to each other.

4. A hydrogen concentration measuring element (100, 100a) according to any one of claims 1 to 3, wherein the protective coating layer (112) is made of an inorganic substance.

5. A hydrogen concentration measuring element (100, 100a) according to any one of claims 1 to 4, wherein the protective coating layer (112) is deposited on the metal wire (111) by chemical vapor deposition.

6. A hydrogen concentration measuring device comprising: the hydrogen concentration measuring element (100, 100a) according to any one of claims 1 to 5; and an information processing unit (33) which calculates a hydrogen concentration from an electrical resistance value of the metal wire (111) of the hydrogen concentration measuring element (100, 100a).

7. A hydrogen concentration measuring device (10) according to claim 6, wherein a measurement target is an atmosphere in a nuclear reactor containment vessel (1).

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