Hydrogen separation device

Abstract

[Problem] To suppress leakage of a mixed gas and / or hydrogen from an end part of a hydrogen permeable membrane in a hydrogen separation device, and to achieve a more compact device. [Solution] A hydrogen separation device for separating and taking out hydrogen from a mixed gas containing hydrogen, the device having a hydrogen separation unit 100 having a storage chamber 110 to which a mixed gas is supplied, a collection chamber 120 for separating and taking out hydrogen, and a boundary part for separating the storage chamber 110 from the collection chamber 120, wherein a plurality of hydrogen permeation parts 130 for taking out hydrogen from the mixed gas are joined to the boundary part of the hydrogen separation unit 100 by welding.

Description

Hydrogen Separator

[0001] The present invention relates to a technology (hydrogen separation device) for separating and extracting hydrogen from a hydrogen-containing mixed gas. The present invention also relates to a hydrogen separation device having a hydrogen permeation section with a joint formed by joining a metal material containing a Group 5 element with a different metal material. The present invention also relates to a metal material containing a Group 5 element that is used to separate hydrogen from a hydrogen-containing mixed gas.

[0002] This application includes, in the following specification, "1. Invention relating to a hydrogen separation device" based on Japanese Patent Application No. 2024-082063, "2. Invention relating to joining of a metal material containing a Group 5 element with a dissimilar metal material different from this metal material" based on Japanese Patent Application No. 2024-082064, and "3. Invention relating to a metal material containing a Group 5 element" based on Japanese Patent Application No. 2024-082065. Below, prior art documents for each invention are listed together in the "Prior Art Documents" section at the beginning. Meanwhile, the background art, problems, means, effects, and embodiments (including examples) of each invention are described in order.

[0003] Techniques for separating hydrogen from a hydrogen-containing mixed gas using a hydrogen-permeable membrane are known. Furthermore, techniques for providing multiple hydrogen-permeable membranes are known to increase the yield of hydrogen separated from a hydrogen-containing mixed gas per unit time. One such technique is a hydrogen separation device that uses a housing having a storage chamber and a collection chamber separated from each other, an inlet formed in the housing for allowing a hydrogen-containing mixed gas to flow in from outside the housing, and multiple membrane modules housed in the storage chambers, each having a hydrogen-permeable membrane, and separating hydrogen from the mixed gas (see Patent Document 1). Another hydrogen separation device uses a hydrogen separation metal membrane 2 divided into four sections to reduce its size (see Patent Document 2).

[0004] In the membrane module for separating hydrogen used in the technology described in Patent Document 1, a punching plate, a metal gasket, a stainless steel fiber body, a hydrogen-permeable membrane, and a metal gasket are sequentially placed in a recess of a support, and then a frame is press-fitted into the recess to fix the hydrogen-permeable membrane.In Patent Document 2, each hydrogen separation metal membrane is sandwiched between a frame member and a support plate.

[0005] JP 2021-13901 A (Claim 1, paragraph 0038, Figure 4) JP 2008-253984 A (paragraphs 0072 to 0074, Figure 11) JP 2020-525270 A (paragraphs

[0005] ,

[0007] ,

[0013] ,

[0021] ,

[0087] to

[0090] , Figure 5 (b)) JP 2019-5684 A (paragraph 0012)

[0006] Yoshinaga et al., "Development of a large-capacity ultra-high-purity hydrogen separation device using vanadium alloy membranes," Materia, Vol. 57, No. 1 (2018), pp. 23-25.

[0007] However, when a hydrogen-permeable membrane having hydrogen permeability is fixed by press-fitting as in Patent Document 1 or clamping as in Patent Document 2, the press-fitting or clamping force must be uniform throughout the entire area where the hydrogen-permeable membrane is fixed. However, achieving uniform press-fitting or clamping force is not easy in terms of mechanical design. If the pressure or clamping force is not uniform, there is a problem that the mixed gas or hydrogen leaks from the edge of the hydrogen-permeable membrane. Similarly, if the pressure or clamping force is not uniform, the stress on the hydrogen-permeable membrane is not uniform, which makes the hydrogen-permeable membrane prone to damage. In addition, the multiple membrane modules described in Patent Document 1 each have a flow path for separating and extracting hydrogen, which makes it difficult to miniaturize the device.

[0008] The present invention was created in consideration of the above problems, and its object is to suppress leakage of mixed gas and hydrogen from the edge of the hydrogen-permeable membrane and to reduce the size of the device.

[0009] The present invention relates to a hydrogen separation device that separates and extracts hydrogen from a mixed gas containing hydrogen, characterized in that it has a hydrogen separation unit having a storage chamber to which the mixed gas is supplied, a collection chamber from which hydrogen is separated and extracted, and a boundary portion separating the storage chamber and the collection chamber, and a plurality of hydrogen permeation portions that can extract the hydrogen from the mixed gas are joined to the boundary portion of the hydrogen separation unit by welding.

[0010] In the present invention, the hydrogen permeation amount per unit volume of the hydrogen separation unit is 2.5×10 －６ (L / min.mm ３ ) or more.

[0011] In the present invention, it is preferable that the hydrogen separation unit is replaceable.

[0012] In the present invention, the pressure applied to the hydrogen permeable portion is preferably an absolute pressure of 200 kPa or less.

[0013] In the present invention, it is preferable that the plurality of hydrogen permeable portions be two or more hydrogen permeable portions provided at the boundary portion.

[0014] In the present invention, it is also preferable that a plurality of holes are provided in the boundary portion, the hydrogen permeable portion is provided as a thin film so as to close the plurality of holes, and an end of the thin film is welded to the boundary portion.

[0015] In the present invention, the thickness of the thin film is preferably 0.05 mm or more and 5 mm or less.

[0016] In addition, in the present invention, it is preferable that a plurality of holes are provided in the boundary portion, and that a plurality of the hydrogen permeation portions formed on the cylinder are inserted into the boundary portion and welded so that the side surface of the cylinder contacts the inner circumference of each of the plurality of holes.

[0017] In the present invention, the cylindrical wall thickness is preferably 0.05 mm or more and 5 mm or less.

[0018] In the present invention, the hydrogen permeable portion is preferably formed of a metal film containing a Group 5 element.

[0019] In the present invention, the hydrogen permeable portion preferably has a configuration in which a metal containing a Group 5 element is adhered to a porous substrate.

[0020] This makes it easier to prevent the mixed gas or hydrogen gas from leaking from the end of the hydrogen permeable portion, and also makes it possible to reduce the size of the device.

[0021] 1 is a perspective view showing an example of a hydrogen separation unit 100 according to the first embodiment. FIG. 1 is an A-A cross-sectional view (vertical cross-section) of the hydrogen separation unit 100 shown in FIG. 1, as viewed from the direction of the arrow indicated by A in FIG. 1. FIG. 2 is an A1-A1 cross-sectional view (vertical cross-section) of the hydrogen separation unit 100 shown in FIG. 1, as viewed from the direction of the arrow indicated by A1 in FIG. 1. FIG. 3 is an enlarged view of the portion enclosed by the rectangular dotted line in FIG. 2. FIG. 4 is a perspective view showing the hydrogen separation unit 100 shown in FIG. 1 with the top cover of the storage chamber removed. FIG. 5 is a diagram illustrating an example of a method for extracting hydrogen from a mixed gas. FIG. 6 is a perspective view showing an example of a hydrogen separation unit 200 according to the second embodiment. FIG. 7 is a B-B cross-sectional view (vertical cross-section) of the hydrogen separation unit 200 shown in FIG. 7, as viewed from the direction of the arrow indicated by B in FIG. 6. FIG. 8 is a B1-B1 cross-sectional view (vertical cross-section) of the hydrogen separation unit 200 shown in FIG. 7, as viewed from the direction of the arrow indicated by B1 in FIG. 6. FIG. 9 is a perspective view showing the hydrogen separation unit 200 shown in FIG. 7 with the upper part (upper 1 / 3) including the top cover of the upper collection chamber removed. 12 is a perspective view showing an example of a hydrogen separation unit 300 according to the third embodiment. It is a CC cross-sectional view (vertical cross-section) of the hydrogen separation unit 300 shown in FIG. 11 , viewed from the direction of the arrow indicated by C in FIG. 10 . It is a perspective view showing a boundary wall 340 to which a plurality of cylindrically formed hydrogen permeation sections 330 are welded, removed from the hydrogen separation unit 300 shown in FIG. 11 . It is a cross-sectional view showing an enlarged view of the portion surrounded by the dotted line in FIG. 12 . It is an example of a manufacturing process for the hydrogen permeation section 330 used in the third embodiment. It is an example of a manufacturing process for welding the hydrogen permeation section 330 to the boundary wall 340 in the third embodiment. It is a schematic diagram showing a state in which a catalyst 390 is applied to the surface of the hydrogen permeation section 330 in the third embodiment. FIG. 18 is a schematic diagram (left) of an electron beam welding apparatus in Example 1, and a schematic diagram (right) showing the state of a metal material (a vanadium membrane with a diameter of 40 mm) and a dissimilar metal material (a ring-shaped stainless steel plate with a diameter of 52 mm and an inner diameter of 30 mm) placed on the workpiece during electron beam welding. FIG. 19 shows SEM observation images of the cross section of the joint in the three samples prepared in Example 1.Figure 20 shows the results of measurements of the hydrogen permeation performance of a sample (effective diameter of the membrane: 30 mm) in which a vanadium membrane was electron-beam welded to the center of the donut-shaped stainless steel ring (diameter: 52 mm) shown in Figure 18 in Example 1, and a normal vanadium membrane (the diameter of the vanadium membrane was 52 mm, but the experimental data was converted to an effective membrane diameter of 30 mm for comparison with the electron-beam welded sample). Figure 21 is a conceptual diagram of the experimental apparatus used in the hydrogen permeation test. Figure 22 is a schematic diagram (left) of the fiber welding apparatus in Example 2, and a schematic diagram (right) showing the state of a metal material (vanadium membrane with a diameter of 40 mm) and a dissimilar metal material (ring-shaped stainless steel plate with a diameter of 52 mm and an inner diameter of 30 mm) placed on the workpiece during fiber welding. Figure 23 shows the results of measuring the hydrogen permeability of a sample (effective diameter of the membrane: 40 mm) in which a vanadium membrane was fiber-welded to the center of a donut-shaped stainless steel ring (diameter: 52 mm) shown in Figure 22 in Example 2, and a normal vanadium membrane (the diameter of the vanadium membrane was 52 mm, but the data obtained in the experiment was converted so that the effective diameter of the membrane was 40 mm for comparison with the electron-beam welded sample). Figure 24 is a schematic diagram of the electron-beam welding equipment in Example 3 and a schematic diagram showing the appearance of two vanadium membranes (plates) placed on the workpiece during electron-beam welding. Figure 25 shows SEM images of the non-bonded and bonded portions in Example 3. Fig. 26 shows the results of measuring the hydrogen permeability of a vanadium membrane (disk-shaped membrane with a diameter of 52 mm) whose center was electron-beam welded in Example 3 and a normal vanadium membrane (disk-shaped membrane with a diameter of 52 mm) without such welding, and a schematic diagram of the measurement sample (vanadium membrane whose center was electron-beam welded) used in the measurement. Fig. 27 shows a schematic diagram of the fiber welding device and the state of two vanadium membranes (plates) placed on the workpiece during fiber welding in Example 4. Fig. 28 shows the results of measuring the hydrogen permeability of a vanadium membrane (disk-shaped membrane with a diameter of 52 mm) whose center was fiber-welded in Example 4 and a normal vanadium membrane (disk-shaped membrane with a diameter of 52 mm) without such welding.

[0022] Preferred embodiments for carrying out the present invention will be described below. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. Furthermore, it goes without saying that the following embodiments may be modified as appropriate within the scope of the gist of the present invention.

[0023] As described at the beginning, the following embodiments sequentially describe "1. Invention relating to a hydrogen separation device" based on Japanese Patent Application No. 2024-082063, "2. Invention relating to joining of a metal material containing a Group 5 element with a dissimilar metal material different from this metal material" based on Japanese Patent Application No. 2024-082064, and "3. Invention relating to a metal material containing a Group 5 element" based on Japanese Patent Application No. 2024-082065. Prior art documents for each invention are listed together in the "Prior Art Documents" section at the beginning.

[0024] 1. Invention Related to Hydrogen Separation Apparatus The hydrogen separation apparatus of the present invention is used to separate and extract hydrogen from a hydrogen-containing mixed gas. It includes a hydrogen separation unit having a storage chamber to which the mixed gas is supplied, a collection chamber from which hydrogen is separated and extracted, and a boundary separating the storage chamber and the collection chamber. A plurality of hydrogen permeable sections capable of extracting hydrogen from the mixed gas are welded to the boundary of the hydrogen separation unit. In other words, by providing a hydrogen permeable section at the boundary separating the storage chamber and the collection chamber, the hydrogen separation unit of the present invention facilitates miniaturization of the device, and by welding the hydrogen permeable section to the boundary, it is easier to suppress leakage of the mixed gas or hydrogen gas. Furthermore, by providing a plurality of hydrogen permeable sections at the boundary, which can extract hydrogen from the mixed gas, the yield of hydrogen that can be separated or extracted per unit time can be increased. This invention is based on Japanese Patent Application No. 2024-082063.

[0025] From the viewpoint of miniaturization, the hydrogen permeation amount per unit volume in the hydrogen separation unit is set to 2.5 × 10 －６ (L / min.mm ３) or more. Here, the hydrogen permeation rate per unit volume in a hydrogen separation unit refers to the value obtained by dividing the amount of hydrogen that can be extracted from one hydrogen separation unit per unit time (one minute) by the volume of this hydrogen separation unit (more specifically, the total volume of the storage chamber to which the mixed gas is supplied and the volume of the collection chamber from which hydrogen is separated and extracted). From the viewpoint of extracting hydrogen more efficiently, the hydrogen permeation rate per unit volume in a hydrogen separation unit is better. The hydrogen permeation rate per unit volume in a hydrogen separation unit is preferably 3 x 10 －６ (L / min.mm ３ ) or more, more preferably 4 × 10 －６ (L / min.mm ３ ) or more, more preferably 5 × 10 －６ (L / min.mm ３ On the other hand, due to the shape of the hydrogen separation unit and its restrictions, the hydrogen permeation amount per unit volume in the hydrogen separation unit is generally 5 × 10 －４ (L / min.mm ３ ) as follows.

[0026] The hydrogen separation device described in Patent Document 1 does not have a hydrogen permeation section at the boundary separating the storage chamber and the collection chamber, and is designed to include multiple membrane modules (multiple collection chambers, so to speak) within the storage chamber, making it difficult to reduce the size of the device. For this reason, the upper limit of the hydrogen permeation amount per unit volume of the storage chamber including multiple membrane modules (multiple collection chambers) is 2.2 × 10 －６ (L / min.mm ３ In contrast, the present invention has made it possible to realize a compact design, which allows for a larger hydrogen permeation amount per unit volume in the hydrogen separation unit, and therefore an improved hydrogen permeation efficiency.

[0027] The hydrogen permeation section of the hydrogen separation device of the present invention has the role of absorbing hydrogen from the mixed gas in the storage chamber and permeating it into the collection chamber. Therefore, as the hydrogen extraction time increases and the extraction process is repeated, the hydrogen permeation section gradually deteriorates and eventually becomes unable to perform its hydrogen extraction function. Specifically, the hydrogen permeation section preferably uses a thin film made of vanadium or a vanadium alloy. However, such a thin film will eventually break or lose its hydrogen permeation function if hydrogen is extracted continuously or intermittently. Therefore, in the hydrogen separation device of the present invention, it is preferable that the hydrogen separation unit is replaceable.

[0028] In the present invention, since multiple hydrogen permeation sections are welded to the boundaries of the hydrogen separation unit, it is more efficient to replace the hydrogen separation unit itself rather than replacing each hydrogen permeation section individually. Furthermore, from the viewpoint that, when the hydrogen permeation function of a hydrogen permeation section is lost, the hydrogen separation unit itself is replaced rather than replacing each hydrogen permeation section individually, the hydrogen separation device of the present invention has preferred operating conditions when separating hydrogen from a hydrogen-containing mixed gas. Specifically, in the present invention, it is preferable that the pressure applied to the hydrogen permeation section be 200 kPa absolute or less. That is, it is preferable to operate the hydrogen separation device so that the pressure of the mixed gas applied to the hydrogen permeation section is controlled to 200 kPa absolute or less. The absolute pressure can be measured by installing a conventionally known pressure sensor at an appropriate location in the device (e.g., in the piping).

[0029] Generally, for a given hydrogen concentration in a mixed gas, increasing the mixed gas pressure applied to the hydrogen permeation section increases the amount of hydrogen that can be extracted. However, increasing the mixed gas pressure increases the burden on the hydrogen permeation section, increasing the probability that the hydrogen permeation function of the hydrogen permeation section will be lost. For example, if a thin film made of vanadium or a vanadium alloy is used as the hydrogen permeation section, increasing the mixed gas pressure makes the thin film more susceptible to damage or tearing, resulting in an earlier loss of hydrogen permeation function. Therefore, in the hydrogen separation device of the present invention, it is preferable to relatively lower the mixed gas pressure applied to the hydrogen permeation section, thereby reducing the burden on the hydrogen permeation section and thereby reducing the frequency of replacement of the hydrogen permeation section and, ultimately, the hydrogen separation unit.

[0030] As described above, in the present invention, the stable operation of the hydrogen separation device can be ensured by relatively reducing the pressure of the mixed gas applied to the hydrogen permeation section and reducing the frequency of replacement of the hydrogen separation unit. However, relatively reducing the pressure of the mixed gas applied to the hydrogen permeation section means that the amount of hydrogen that can be extracted from the hydrogen permeation section is relatively small. Therefore, in the present invention, the hydrogen separation device is designed so that multiple hydrogen permeation sections are installed at the boundary section and the total hydrogen permeation amount is sufficient. Specifically, it is preferable to provide two or more hydrogen permeation sections at the boundary section as the multiple hydrogen permeation sections. Since the amount of hydrogen extracted can be increased by increasing the number of hydrogen permeation sections, the number of hydrogen permeation sections is more preferably three or more, even more preferably five or more, particularly preferably seven or more, and most preferably ten or more. Meanwhile, due to the size relationship between the storage chamber, the collection chamber, and the boundary section, the number of hydrogen permeation sections is generally set to 300 or less.

[0031] The hydrogen separation unit used in the hydrogen separation device of the present invention preferably has a plurality of holes formed in the boundary portion, the hydrogen permeation portion being formed as a thin film so as to cover the plurality of holes, and the edge of the thin film being welded to the boundary portion. Specific examples of such a hydrogen separation unit are described below.

[0032] [First embodiment] (Hydrogen separation unit) Fig. 1 is a perspective view showing an example of a hydrogen separation unit 100 according to a first embodiment. Fig. 2 is an A-A cross-sectional view (vertical cross-section) of the hydrogen separation unit 100 shown in Fig. 1, as viewed from the direction of the arrow indicated by A in Fig. 1. Fig. 3 is an A1-A1 cross-sectional view (vertical cross-section) of the hydrogen separation unit 100 shown in Fig. 1, as viewed from the direction of the arrow indicated by A1 in Fig. 1. Fig. 4 is an enlarged view of the portion enclosed by the dotted square line in Fig. 2. Fig. 5 is a perspective view showing the hydrogen separation unit 100 shown in Fig. 1 with the top cover of the storage chamber removed.

[0033] The hydrogen separation unit 100 has a generally disk-shaped exterior. The internal structure of the hydrogen separation unit 100 includes a storage chamber 110, to which a mixed gas is supplied, and a collection chamber 120, from which hydrogen is separated and extracted, separated by a boundary formed by a boundary wall 140 and rings 170a-170g. More specifically, the boundary is formed by a plurality of (seven) holes in the boundary wall 140, and rings 170a-170g are welded to one surface (the upper surface in FIGS. 2-4 ) of the boundary wall 140 and to the outer periphery of each hole. The boundary is formed by the boundary wall 140 and the rings 170a-170g. Furthermore, a plurality of hydrogen permeation sections 130a-130g (thin films) are welded to the inner peripheral regions of the rings 170a-170g that are not joined to the boundary wall 140, so as to cover each hole. 2 and 3, for convenience of drawing, the hydrogen permeable sections 130a to 130g and the boundary wall 140 are drawn to have the same thickness. However, in reality, the hydrogen permeable sections 130a to 130g are thin films, as will be described later, and therefore, as shown in FIG. 4, the thickness of the boundary wall 140 is greater than the thickness of the hydrogen permeable sections 130a to 130g.

[0034] 2, 3, and 4, the ends of the hydrogen permeable portions 130a to 130g are welded to the boundary wall 140 via rings 170a to 170g. The rings 170a to 170g are made of the same material as the boundary wall 140 and are joined to the boundary wall 140 by welding, and the hydrogen permeable portions 130a to 130g are placed on the inner peripheral portions of the rings 170a to 170g that are not welded to the boundary wall 140. The rings 170a to 170g are then welded to the hydrogen permeable portions 130a to 130g. By welding the hydrogen permeable portions 130a to 130g to the rings 170a to 170g, each hole in the boundary portion is sealed.

[0035] The storage chamber 110 is provided with a supply pipe 150 for introducing the mixed gas and an exhaust pipe 151 for discharging the gas discharged after hydrogen is extracted from the mixed gas, and the collection chamber 120 is provided with a collection pipe 160 for extracting hydrogen gas.

[0036] The housings of the storage chamber 110 and the collection chamber 120 are made of stainless steel. When the storage chamber 110 is filled with the mixed gas and the collection chamber 120 is filled with hydrogen, the housings of the storage chamber 110 and the collection chamber 120 have sufficient thickness to prevent gas leakage and ensure mechanical strength. The boundary wall 140 is also made of stainless steel, and for the same reasons as above, has a thickness sufficient to prevent gas leakage and ensure mechanical strength. The rings 170a to 170g are also made of stainless steel. The supply pipe 150, discharge pipe 151, and collection pipe 160 are also made of stainless steel.

[0037] The hydrogen permeation sections 130a-130g are formed as disc-shaped thin films. This disc-shaped thin film is preferably a metal film containing a Group 5 element. This is because metal films containing a Group 5 element have the excellent property of selectively separating and allowing hydrogen to permeate from mixed gases. The Group 5 element is preferably at least one selected from the group consisting of vanadium, niobium, and tantalum, and vanadium (pure vanadium) is even more preferable. Group 5 elements such as vanadium, particularly so-called vanadium group elements, have similar chemical properties. Since vanadium has the property of permeating hydrogen, other Group 5 elements, particularly vanadium group elements, also have similar properties. In the present invention, a Group 5 element is used for the metal film, but as described above, Group 5 elements have similar chemical properties, so they may be used in combination. For example, vanadium may coexist with niobium or tantalum, or an alloy thereof may be formed.

[0038] Furthermore, the metal membranes used as the hydrogen permeation sections 130a-130g may contain elements other than Group 5 elements. The inclusion of such elements facilitates imparting various properties to the metal membrane. Examples of such elements include iron (Fe), ruthenium (Ru), aluminum (Al), tungsten (W), molybdenum (Mo), chromium (Cr), and cobalt (Co). The use of these alloying elements facilitates imparting rigidity to the hydrogen permeation sections 130a-130g (hydrogen separation membranes), suppressing the hydrogen solid solubility (also known as hydrogen solubility) in the alloy even when the applied hydrogen pressure is increased, and contributing to improved hydrogen embrittlement resistance. The content of elements other than Group 5 elements is typically 0.1 atomic % or more, preferably 1 atomic % or more, for each element. This range facilitates imparting the properties described above to the metal membrane. Meanwhile, the content of elements other than Group 5 elements is typically 50 atomic % or less, preferably 40 atomic % or less, and more preferably 11 atomic % or less, for each element. Within this range, the advantages of using a Group 5 element are not diminished and the required properties can be easily imparted.

[0039] The content of Group 5 elements and other elements in the hydrogen permeable portions 130a to 130g (hydrogen separation membranes) can be analyzed by the following method: Using a scanning electron microscope (SEM / EDS / WDS) equipped with an EDS or WDS or a field emission scanning electron microscope (FE-SEM / EDS / WDS), the types and compositions of the contained elements can be analyzed by setting appropriate analytical conditions.

[0040] The thickness of the hydrogen permeable sections 130a-130g (hydrogen separation membranes) is set to 0.05 mm or more here. Generally, the thicker the hydrogen permeable sections 130a-130g (hydrogen separation membranes), the greater the mechanical strength. This makes the membrane less susceptible to breakage and allows hydrogen to permeate well over a long period of time. On the other hand, increasing the thickness of the hydrogen permeable sections 130a-130g (hydrogen separation membranes) tends to reduce the amount of hydrogen that can permeate per unit time. For this reason, the thickness of the hydrogen permeable sections 130a-130g (hydrogen separation membranes) must be appropriately controlled. From these perspectives, the thickness of the hydrogen permeable sections 130a-130g (hydrogen separation membranes) is preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more. However, it is typically 5 mm or less, preferably 1 mm or less. The thickness of the hydrogen permeable portions 130a to 130g (hydrogen separation membranes) may be measured using a known measuring device such as a finger, a vernier caliper, a micrometer, or a 3D shape measuring device, depending on the thickness.

[0041] In the present invention, the Vickers hardness of the hydrogen permeable portions 130a to 130g (hydrogen separation membranes) is preferably 80 HV or higher. This range makes it easier to soften the hydrogen permeable portions 130a to 130g (hydrogen separation membranes) and ensure toughness. On the other hand, from the perspective of hardening the hydrogen permeable portions 130a to 130g (hydrogen separation membranes) and ensuring mechanical strength, the Vickers hardness is preferably 100 HV or higher, more preferably 120 HV or higher, particularly preferably 130 HV or higher, and most preferably 150 HV or higher. When a metal containing a Group 5 element (as mentioned above, the chemical properties of Group 5 elements, particularly vanadium group elements, are very similar) is used for the hydrogen permeable portions 130a to 130g (hydrogen separation membranes), the Vickers hardness is generally 500 HV or lower, and typically 300 HV or lower. The Vickers hardness may be measured using a commercially available Vickers hardness tester (for example, a micro Vickers hardness tester (for example, the HM-100 series manufactured by Mitutoyo Corporation)).

[0042] The ends of the hydrogen permeable sections 130a-130g are joined by welding to rings 170a-170g joined to the boundary wall 140. There are no particular limitations on the welding method, and when hydrogen separation membranes containing Group 5 elements are used as the hydrogen permeable sections 130a-130g, any welding method can be selected that ensures a good connection between the hydrogen separation membrane and the material of the rings 170a-170g. The width of the rings 170a-170g can be selected appropriately to ensure a good connection between the boundary wall 140 and the hydrogen permeable sections 130a-130g. However, because the rings 170a-170g do not contribute to the extraction of hydrogen, it is preferable not to make the size (area) of the hydrogen permeable sections 130a-130g unnecessarily small. From this viewpoint, the contact area between the disk-shaped hydrogen permeable portions 130a to 130g and the rings 170a to 170g, near the outer periphery of the disk-shaped hydrogen permeable portions 130a to 130g, is preferably 2% or more of the diameter of the disk-shaped hydrogen permeable portions 130a to 130g, and more preferably 5% or more, while it is preferably 15% or less of the diameter of the disk-shaped hydrogen permeable portions 130a to 130g, and more preferably 10% or less.

[0043] There are no particular limitations on the welding method. When a hydrogen separation membrane containing a Group 5 element is used as the hydrogen permeation portion 130a-130g, the joint between the hydrogen separation membrane and the material of the rings 170a-170g is heated to a temperature above the melting point to complete the welding. Although there are no limitations on the welding method, from an industrial perspective, it is preferable to use electron beam welding, laser welding, or TIG welding. Of these, when using electron beam welding, it is preferable to perform the welding in a vacuum. Welding in a vacuum makes it easier to prevent impurities from being mixed into the weld. When using laser welding, it is more preferable to use a solid-state laser from the perspective of achieving high-precision, high-density welding, and fiber welding using a fiber laser is preferable. Furthermore, TIG welding has the advantage of being easy to weld, requiring little labor, and low cost from an industrial perspective.

[0044] (Hydrogen Separation Apparatus) Next, a hydrogen separation apparatus including a hydrogen separation unit 100 will be described. Since the hydrogen separation unit 100 is preferably used while heated as described below, it is installed in a heater, with the supply pipe 150 connected to an external mixed gas supply device (not shown), the discharge pipe 151 connected to an external exhaust gas collection tank (not shown), and the collection pipe 160 connected to an external storage tank (not shown). In this state, it functions as a hydrogen separation apparatus. Below, the operation of this hydrogen separation apparatus will be described, specifically, an example of a method for extracting hydrogen from a mixed gas. FIG. 6 is a diagram illustrating an example of a method for extracting hydrogen from a mixed gas. Here, it is assumed that a metal membrane containing a Group 5 element is used for the hydrogen permeation sections 130a to 130g.

[0045] First, in the initial stage, the heater is operated to heat the hydrogen separation unit 100 to a predetermined temperature (step S0). This is because it is preferable to heat the metal membrane containing a Group 5 element (e.g., to 300 to 400°C) in order to enable the metal membrane to exhibit its hydrogen separation function. Next, a mixed gas sent from an external mixed gas supply device (not shown) is introduced into the accommodation chamber 110 through the supply pipe 150 (step S1).

[0046] When the mixed gas flows into the storage chamber 110 and reaches a predetermined pressure, hydrogen contained in the mixed gas permeates through the hydrogen permeation sections 130a-130g and moves to the collection chamber 120. This separates hydrogen from the mixed gas (step S2). More specifically, all or a portion of the hydrogen contained in the mixed gas flowing into the storage chamber 110 permeates through the metal membranes containing Group 5 elements, which are the hydrogen permeation sections 130a-130g, and moves to the collection chamber 120. The remaining mixed gas after hydrogen separation is then sent through the exhaust pipe 151 to an external exhaust gas collection tank (not shown) (step S3). As described above, in the present invention, it is preferable to operate the hydrogen separation unit 100 by controlling the pressure applied to the hydrogen permeation sections 130a-130g to an absolute pressure of 200 kPa or less. This control allows the hydrogen permeation rate per unit volume (the yield of hydrogen that can be separated or extracted per unit time) to be maintained while extending the replacement life of the hydrogen separation unit 100.

[0047] Meanwhile, the hydrogen extracted into the collection chamber 120 is sent to the outside through the collection pipe 160 (step S4). The separated hydrogen is then collected in an external storage tank (not shown).

[0048] According to the first embodiment, there are seven hydrogen permeable sections 130a-130g, which are welded to the rings 170a-170g and joined to the boundary sections (the boundary sections formed by the boundary wall 140 and the rings 170a-170g). This reduces gas leakage at the joined sections, making it easier to prevent the mixed gas from leaking into the collection chamber 120 from the ends of the hydrogen permeable sections 130a-130g and the hydrogen gas from leaking (backflowing) into the storage chamber 110. Furthermore, multiple (seven) holes are formed in the boundary wall 140, and the hydrogen permeable sections 130a-130g are installed so as to block each hole, making it easier to miniaturize the hydrogen separation unit 100. Based on the above, the seven hydrogen permeable sections 130a-130g allow for a greater amount of hydrogen to be extracted from the entire hydrogen separation unit 100. Furthermore, as a secondary effect, the hydrogen separation unit 100 can be operated stably for a long period of time. In other words, since the amount of hydrogen extracted from the entire hydrogen separation unit 100 can be increased, there is no need to increase the pressure inside the storage chamber 110, which is required to separate hydrogen from the mixed gas. More specifically, the pressure applied to the hydrogen permeation sections 130a-130g can be set to an absolute pressure of 200 kPa or less. As a result, the load (pressure) applied to the metal membranes containing Group 5 elements used in the hydrogen permeation sections 130a-130g can be reduced, making each metal membrane less likely to be damaged. This means that the replacement frequency of the hydrogen separation unit 100 can be reduced, enabling the hydrogen separation unit 100 to be operated stably for a long period of time. Here, the absolute pressure is measured using a pressure sensor (not shown) installed in the piping (supply pipe 150).

[0049] In particular, in the first embodiment, because the hydrogen permeable sections 130a-130g are joined to the boundaries (more specifically, the rings 170a-170g that make up the boundaries) by welding, it is not primarily intended that the hydrogen permeable sections 130a-130g will be replaced one by one. In other words, if a hydrogen permeable section is damaged or loses its hydrogen permeability, it is primarily intended that the hydrogen separation unit 100 will be replaced. Therefore, it is preferable to reduce the replacement frequency of the hydrogen separation unit 100, in other words, to operate the hydrogen separation unit 100 stably for a long period of time. For this reason, it is preferable to control the operating conditions of the hydrogen separation device (conditions under which the hydrogen permeable sections are operated without any load being applied) as described above.

[0050] [Second embodiment] (Hydrogen separation unit) Figure 7 is a perspective view showing an example of a hydrogen separation unit 200 according to a second embodiment. Figure 8 is a B-B cross-sectional view (vertical cross-section) of the hydrogen separation unit 200 shown in Figure 7, viewed from the direction of the arrow indicated by B in Figure 7. Figure 9 is a B1-B1 cross-sectional view (vertical cross-section) of the hydrogen separation unit 200 shown in Figure 7, viewed from the direction of the arrow indicated by B1 in Figure 7. Figure 10 is a perspective view showing the hydrogen separation unit 200 shown in Figure 7 with the upper part (upper 1 / 3) including the top cover of the upper collection chamber removed.

[0051] The hydrogen separation unit used in the present invention only needs to have a storage chamber to which a mixed gas is supplied, a collection chamber from which hydrogen is separated and extracted, and a boundary portion separating the storage chamber and the collection chamber, and additional elements may be added. The second embodiment is an example in which a collection chamber is further added to the hydrogen separation unit of the first embodiment. Specifically, the hydrogen separation unit has collection chambers installed above and below the storage chamber, and the storage chamber is sandwiched between the two collection chambers from above and below. 8 and 9, for convenience of drawing, the hydrogen permeable portions 231a-231g (partially not shown; the same applies below) and 232a-232g are depicted as having the same thickness as the boundary walls 241 and 242. However, as in the first embodiment, the hydrogen permeable portions 231a-231g and 232a-232g are actually thin films, and therefore the boundary walls 241 and 242 are thicker than the hydrogen permeable portions 231a-231g and 232a-232g (see FIG. 4). In this embodiment, the boundary wall 241 and the rings 271a-271g (partially not shown; the same applies below) form a first boundary (upper boundary), and the boundary wall 242 and the rings 272a-272g form a second boundary (lower boundary).

[0052] The hydrogen separation unit 200 has a generally disk-shaped appearance. The hydrogen separation unit 200 has collection chambers 221, 222 above and below a storage chamber 210 to which a mixed gas is supplied, for separating and extracting hydrogen. The storage chamber 210 and the collection chamber 221 are separated by a boundary wall 241, and the storage chamber 210 and the collection chamber 222 are separated by a boundary wall 242. A plurality of (seven) holes are formed in the boundary wall 241, and a plurality of hydrogen permeation sections 231a-231g are provided as thin films via rings 271a-271g to cover the holes. Furthermore, the ends of the hydrogen permeation sections 231a-231g are joined by welding to the rings 271a-271g that form the boundary section (first boundary section). Similarly, a plurality of (seven) holes are provided in the boundary wall 242, and a plurality of hydrogen permeable portions 232a to 232g are provided as thin films via rings 272a to 272g to cover the holes. Furthermore, the ends of the hydrogen permeable portions 232a to 232g are joined by welding to the rings 272a to 272g that form the boundary (second boundary).

[0053] The accommodation chamber 210 of the hydrogen separation unit 200 is provided with a supply pipe 250 for introducing the mixed gas and a discharge pipe 251 for discharging the gas discharged after hydrogen is extracted from the mixed gas, and the collection chamber 221 is provided with a collection pipe 261 for extracting hydrogen gas. Similarly, the collection chamber 222 is provided with a collection pipe 262 for extracting hydrogen gas.

[0054] The materials and thicknesses of the housings of the storage chamber 210 and the collection chambers 221 and 222, the materials of the supply pipe 250 and the collection pipes 261 and 262, and the shapes and materials of the hydrogen permeable portions 231a to 231g and 232a to 232g may be the same as those of the first embodiment. The positional relationship between the rings 271a to 271g and 272a to 272g and the boundary walls 241 and 242, and the positional relationship between the rings 271a to 271g and 272a to 272g and the hydrogen permeable portions 231a to 231g and 232a to 232g may also be the same as those of the first embodiment. Similarly, the welding of the ends of the hydrogen permeable portions 231a to 231g and 232a to 232g may also be the same as those of the first embodiment.

[0055] (Hydrogen Separation Apparatus) Next, a hydrogen separation apparatus including a hydrogen separation unit 200 will be described. As in the first embodiment, the hydrogen separation unit 200 is installed in a heater. Then, the supply pipe 250 is connected to an external mixed gas supply device (not shown), the discharge pipe 251 is connected to an external exhaust gas collection tank (not shown), and the collection pipes 261 and 262 are each connected to an external storage tank (not shown). In this state, the hydrogen separation apparatus functions as a hydrogen separation apparatus. Below, the operation of this hydrogen separation apparatus, specifically, an example of a method for extracting hydrogen from a mixed gas, will be described with reference to FIG. 6. Here, it is assumed that the hydrogen permeation portions 231a to 231g and 232a to 232g use metal membranes containing a Group 5 element, as in the first embodiment.

[0056] First, in the start stage, the hydrogen separation unit 200 is heated to a predetermined temperature (step S0), as in the first embodiment. Next, a mixed gas sent from an external device (not shown) is introduced into the accommodation chamber 210 through the supply pipe 250 (step S1).

[0057] When the mixed gas flows into the storage chamber 210 and reaches a predetermined pressure, hydrogen contained in the mixed gas permeates through the hydrogen permeation sections 231a to 231g provided in the boundary wall 241 and moves to the collection chamber 221, and also permeates through the hydrogen permeation sections 232a to 232g provided in the boundary wall 242 and moves to the collection chamber 222. This separates the hydrogen from the mixed gas (step S2). More specifically, all or a portion of the hydrogen contained in the mixed gas that flows into the storage chamber 210 permeates through the metal membranes containing a Group 5 element, which are the hydrogen permeation sections 231a to 231g, and moves to the collection chamber 221. In addition, all or a portion of the hydrogen contained in the mixed gas that flows into the storage chamber 210 permeates through the metal membranes containing a Group 5 element, which are the hydrogen permeation sections 232a to 232g, and moves to the collection chamber 222. The remaining mixed gas after hydrogen separation is then sent to the outside through the exhaust pipe 251 (step S3). As described above, in the present invention, it is preferable to operate the hydrogen separation unit 200 while controlling the pressure applied to the hydrogen permeation sections 231a to 231g and 232a to 232g to an absolute pressure of 200 kPa or less. By performing such control, it is possible to extend the replacement life of the hydrogen separation unit 200 while ensuring the hydrogen permeation amount per unit volume (the yield of hydrogen that can be separated or extracted per unit time). Here, the absolute pressure is measured using a pressure sensor (not shown) installed in the piping (supply pipe 250).

[0058] Meanwhile, the hydrogen extracted into the collection chamber 221 is sent to the outside through the collection pipe 261 (step S4). The separated hydrogen is then collected in an external storage tank or the like (not shown). Similarly, the hydrogen extracted into the collection chamber 222 is sent to the outside through the collection pipe 262 (step S4). The separated hydrogen is then collected in an external storage tank or the like (not shown).

[0059] The second embodiment has the same basic configuration as the first embodiment, and therefore has the same functions as the first embodiment. In addition, the second embodiment employs a configuration in which boundary walls 241, 242 are provided above and below the storage chamber 210, so that hydrogen can be extracted from both the upper and lower sides of the storage chamber 210 into the collection chambers 221, 222. This allows a greater amount of hydrogen to be extracted.

[0060] [Third embodiment] (Hydrogen separation unit) In the present invention, it is also preferable that a plurality of holes are provided at the boundary portion of the hydrogen separation unit, and a plurality of hydrogen permeation portions formed on a cylinder are inserted into the boundary portion and welded so that the side surface of the cylinder contacts the inner periphery of each of the plurality of holes. By adopting such a structure, it is easy to increase the amount of hydrogen permeation and also to make the hydrogen separation unit and, in turn, the hydrogen separation device more compact. An example of an embodiment utilizing this design is described below.

[0061] FIG. 11 is a perspective view showing an example of a hydrogen separation unit 300 according to a third embodiment. FIG. 12 is a cross-sectional view (vertical cross section) of the hydrogen separation unit 300 shown in FIG. 11 taken along the line C-C, as viewed from the direction of the arrow C in FIG. 11. FIG. 13 is a perspective view showing a boundary wall 340, to which multiple cylindrically formed hydrogen permeation sections 330 are welded, removed from the hydrogen separation unit 300 shown in FIG. 11. Note that although only seven hydrogen permeation sections 330 are shown in FIG. 13, in reality, three are located on the far side of the page, for a total of ten hydrogen permeation sections 330 (this also applies to FIG. 16, which will be described later). FIG. 14 is an enlarged cross-sectional view of the area surrounded by the dotted line in FIG. 12. In this embodiment, the boundary wall 340 serves as the boundary section.

[0062] The hydrogen separation unit 300 has a generally cylindrical appearance. The interior of the hydrogen separation unit 300 is structured such that a storage chamber 310, to which the mixed gas is supplied, and a collection chamber 320 are separated by a boundary wall 340. A cylindrical hydrogen permeation section 330a has one end (bottom) closed, and the other end (top) is inserted into a hole provided in the boundary wall 340, and the side of the upper end of the cylinder is welded and joined to the boundary wall 340 via a joint 370a. Similarly, a cylindrical hydrogen permeation section 330b has one end (bottom) closed, and the other end (top) is inserted into a hole provided in the boundary wall 340, and the side of the upper end of the cylinder is welded and joined to the boundary wall 340 via a joint 370b. This structure is similar to that of the hydrogen permeation sections 330c to 330g. That is, cylindrical hydrogen permeation sections 330a to 330g, each having one closed end and the other open end, are inserted into boundary wall 340 and joined by welding so that the outer surface of the other end contacts the inner periphery of a plurality of holes formed in boundary wall 340.

[0063] The storage chamber 310 of the hydrogen separation unit 300 is provided with a supply pipe 350 for introducing the mixed gas and an exhaust pipe 351 for discharging the gas discharged after hydrogen is extracted from the mixed gas, and the collection chamber 320 is provided with a collection pipe 360 ​​for extracting hydrogen gas.

[0064] The material and thickness of the housing of the storage chamber 310 and the collection chamber 320, i.e., the housing of the hydrogen separation unit 300, the material and thickness of the boundary wall 340, the materials of the supply pipe 350, the discharge pipe 351, and the collection pipe 360, and the material of the hydrogen permeation sections 330a to 330g may be the same as those in the first embodiment. Similarly, the method of welding the hydrogen permeation sections 330a to 330g to the boundary wall 340 may also be the same as or follow that of the first embodiment.

[0065] However, the major difference between the third embodiment and the first and second embodiments is the shape of the hydrogen permeation portion 330. While the first and second embodiments used a disk-shaped thin film, the third embodiment uses a cylindrical (tubular) hydrogen permeation portion 330 with one end closed and the other open. Here, the thickness of the tubular portion is determined taking into consideration the ease of forming the tubular shape, hydrogen permeation performance, etc., as described below, and is typically 0.05 mm, preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more, while typically 5 mm or less, preferably 1 mm or less.

[0066] The method for manufacturing the hydrogen permeation portion 330 of the third embodiment is not particularly limited. Fig. 15 shows an example of a manufacturing process for the hydrogen permeation portion 330 used in the third embodiment. First, a flat thin film (preferably a metal film containing a Group 5 element) is prepared (step (a)), which is then rolled into a cylindrical shape (step (b)). The ends of the side surfaces of the cylinder are welded (step (c)), and the cylindrical shape is completed (step (d)). Next, the bottom surface is sealed (step (e)), and the bottom surface and the side surface are welded (step (f)), completing the product (step (g)).

[0067] In the third embodiment, the manufacturing method for welding the hydrogen permeable portion 330 to the boundary wall 340 is not particularly limited, and may be the same as or follow that of the first embodiment. Figure 16 shows an example of a manufacturing process for welding the hydrogen permeable portion 330 to the boundary wall 340 in the third embodiment. Ten hydrogen permeable portions 330, each having a cylindrical shape with one end closed and the other end open, manufactured by the manufacturing process described above are prepared (only seven of the ten are shown in Figure 16), and the other end of each hydrogen permeable portion 330 is inserted into the boundary wall 340 (step (a)). The inserted portion is then welded (step (b)).

[0068] In the third embodiment, a catalyst that dissociates hydrogen may be present on the surface of the hydrogen permeable portion 330. The presence of such a catalyst facilitates dissociation of hydrogen molecules into hydrogen atoms when in contact with the surface of the hydrogen permeable portion 330, thereby increasing hydrogen permeability. There are no particular limitations on such catalysts as long as they exhibit the above-described effects, but examples include palladium silver (Pd-25% Ag). Methods for providing a catalyst on the surface of the hydrogen permeable portion 330 include sputtering, vapor deposition, and CVD (chemical vapor deposition). From an industrial perspective, sputtering is preferred. The catalyst is preferably present on the surface of the hydrogen permeable portion 330 in the form of a thin film. While palladium silver (Pd-25% Ag) was used as the catalyst in the above example, other catalysts such as palladium copper (Pd—Cu), palladium gold (Pd—Au), and palladium (Pd) can also be used.

[0069] When the catalyst is present in the form of a thin film on the surface of the hydrogen permeable portion 330, the catalyst may be present on the entire surface. However, the welded portion may be weak in terms of strength against hydrogen permeation. Furthermore, if the welded portion has a complex composition of the elements of the catalyst and the hydrogen permeable portion, unexpected problems may occur. From these perspectives, it is possible to avoid the presence of the catalyst in the welded portion. Because catalysts have the effect of dissociating hydrogen, the presence of a catalyst in the welded portion may promote hydrogen dissociation at the welded portion, which may result in the welded portion becoming more susceptible to hydrogen embrittlement. In such cases, the catalyst may be present on the surface of the hydrogen permeable portion 330, avoiding the welded portion.

[0070] FIG. 17 is a schematic diagram showing a state in which a catalyst is applied to the surface of the hydrogen permeation portion 330 in the third embodiment. A thin, plate-like hydrogen permeation portion 330 is formed into a cylindrical shape and joined with a weld 380 to form a cylindrical hydrogen permeation portion 330. One end (bottom) of the hydrogen permeation portion 330 is sealed and welded with a disk made of the same material as the hydrogen permeation portion 330, making it easier to ensure sufficient hydrogen permeation. In this case, providing a thin film of catalyst 390 avoiding the weld 380 makes it easier to prevent damage to the hydrogen permeation portion 330 as described above. While the catalyst has been described above using the third embodiment, the fact that a catalyst that dissociates hydrogen is present (applied) on the surface of the hydrogen permeation portion is also desirable in the first and second embodiments. Here, one end of the cylindrical hydrogen permeation portion 330 is sealed and welded with a disk made of the same material as the hydrogen permeation portion 330, but the material of this disk is not limited. For example, iron (Fe), stainless steel, or other materials may be used as the disk material. When the disk is made of a material that does not have hydrogen permeability, such as iron (Fe) or SUS, there is no need to provide the catalyst 390 on its surface.

[0071] (Hydrogen Separation Apparatus) Next, a hydrogen separation apparatus including a hydrogen separation unit 300 will be described. As in the first and second embodiments, the hydrogen separation unit 300 is installed in a heater. Then, the supply pipe 350 is connected to an external mixed gas supply device (not shown), the discharge pipe 351 is connected to an external exhaust gas collection tank (not shown), and the collection pipe 360 ​​is connected to an external storage tank (not shown). In this state, the hydrogen separation apparatus functions as a hydrogen separation apparatus. Below, the operation of this hydrogen separation apparatus, specifically, an example of a method for extracting hydrogen from a mixed gas, will be described with reference to FIG. 6. Here, as in the first and second embodiments, it is assumed that a metal membrane containing a Group 5 element is used as the material for the hydrogen permeation sections 330a to 330g (and the three hydrogen permeation sections 330 not shown).

[0072] First, in the start stage, the hydrogen separation unit 300 is heated to a predetermined temperature (step S0), as in the first and second embodiments. Next, a mixed gas sent from an external device (not shown) is introduced into the accommodation chamber 310 through the supply pipe 350 (step S1).

[0073] When the mixed gas flows into the storage chamber 310 and the pressure in the storage chamber 310 reaches a predetermined level, hydrogen contained in the mixed gas permeates through the cylindrical hydrogen permeation sections 330a-330g (and three hydrogen permeation sections 330 not shown) provided in the boundary wall 340, each having one closed end and the other open end, and moves to the collection chamber 320. This separates the hydrogen from the mixed gas (step S2). More specifically, all or part of the hydrogen contained in the mixed gas that has flowed into the storage chamber 310 permeates through the hydrogen permeation sections 330a-330g (and three hydrogen permeation sections 330 not shown), which are metal membranes containing Group 5 elements, and moves to the collection chamber 320. The remaining mixed gas after hydrogen separation is then sent to the outside through the exhaust pipe 351 (step S3). As described above, in the present invention, it is preferable to operate the hydrogen permeation sections 330a to 330g (and the three hydrogen permeation sections 330 not shown) by controlling the pressure thereon to an absolute pressure of 200 kPa or less. By performing such control, it is possible to extend the replacement life of the hydrogen separation unit 300 while ensuring the hydrogen permeation amount per unit volume (the yield of hydrogen that can be separated or extracted per unit time). Here, the absolute pressure is measured using a pressure sensor (not shown) installed in the piping (supply pipe 350).

[0074] Meanwhile, the hydrogen extracted into the collection chamber 320 is sent to the outside through the collection pipe 360 ​​(step S4). The separated hydrogen is then collected in an external storage tank or the like (not shown).

[0075] In the third embodiment, the hydrogen permeable section 330 has a cylindrical shape with a closed bottom (one end) and an open top (the other end). As a result, the surface area of ​​the hydrogen permeable section 330 can be relatively increased, further increasing the amount of hydrogen extracted. In the third embodiment, ten hydrogen permeable sections are used (seven are shown in the figure), but increasing the number of sections further increases the amount of hydrogen extracted.

[0076] [Modifications] While the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope of the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments.

[0077] One such example is a modified hydrogen permeable portion. In the above embodiments, an example was described in which the hydrogen permeable material was formed of a metal membrane, but the hydrogen permeable portion may have a form in which a metal containing a Group 5 element is attached to a porous substrate. There are no particular limitations on the hydrogen permeable portion having such a form. For example, a dense, crystalline Pd / V layer having a total thickness of less than 7 mm is formed on porous alumina, as described in a paper (Stefano Fasolin et al., "Hydrogen separation by thin vanadium-based multi-layered membranes," INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 43 (2018) 3235-3243). ９３ Pd ７ Examples of such a porous film include a porous film formed by depositing a Pd / Pd multilayer film.

[0078] 2. Invention relating to joining of a metal material containing a Group 5 element with a dissimilar metal material different from this metal material Hereinafter, as an invention according to one aspect of the present invention, a structure having a joint in which a metal material containing a Group 5 element and a dissimilar metal material different from this metal material are explained (hereinafter in this section, the invention according to the above structure will be referred to as "the present invention"). This invention is based on Japanese Patent Application No. 2024-082064.

[0079] BACKGROUND ART Hydrogen (H ２There is a separation technology for separating hydrogen from hydrogen. This separation technology uses a membrane-based separation technology, and a vanadium-based membrane (i.e., a vanadium or vanadium alloy-based membrane) is used as the membrane (hydrogen-selective membrane). A brazing technology is known in which the vanadium-based membrane is laser-welded to a different metal, preferably stainless steel (Patent Document 3).

[0080] (Problem to be solved) To extract hydrogen (H ２ When a hydrogen-permeable membrane made of a metal belonging to Group 5, such as vanadium (V), niobium (Nb), or tantalum (Ta), or an alloy of these metals, is used to separate hydrogen (H), it is necessary to attach this hydrogen-permeable membrane to the housing of the hydrogen separation device. The inventors have investigated this point and found that when the brazing technique using laser welding of Patent Document 3 is used, impurities such as brazing material dissolve into the hydrogen-permeable membrane made of vanadium or the like at the welded joint. As a result, it has become possible to separate hydrogen (H) from a mixed gas flow using a hydrogen-permeable membrane. ２ It was found that when separating the two, hydrogen embrittlement occurs at the joint where these impurities have dissolved, and the joint breaks down if the separation time is long.

[0081] The present invention was created in consideration of the above problems, and aims to provide a structure having a joint where a metal material containing a Group 5 element and a dissimilar metal material different from the metal material are joined, which can provide good hydrogen separation function.

[0082] (Means for Solving the Problem) In Comparative Experimental Example 1 of Patent Document 3, direct laser welding (welding without using brazing filler metal) is performed, but large crystal grains present at the joint are said to be the cause of cracking and fracture, and direct laser welding technology is said to be unsuitable for joining and sealing vanadium-based films to stainless steel or other metal joints.

[0083] However, according to the inventors' investigations, the reason why Patent Document 3 states that direct laser welding is not suitable is because the bonding area of ​​the bonding portion is insufficient (taking into consideration that Patent Document 3 states that a vanadium-based film thickness of 0.2 to 0.5 mm is more preferable, and looking at the cross-sectional photograph of Comparative Experimental Example 1 (FIG. 5(b)), the width of the bonding portion is considered to be 200 μm or less), and it has been found that the size of the crystal grains is not the cause. Rather, the inventors' investigations have found that by ensuring a sufficient bonding area, the problem of hydrogen embrittlement due to the dissolution of impurities can be solved, while also solving the problems of cracking and shattering of the hydrogen-permeable film.

[0084] The present invention provides a structure having a joint where a metal material containing a Group 5 element is joined to a dissimilar metal material different from the metal material, wherein the metal material is used to separate hydrogen from a hydrogen-containing mixed gas, the joint is formed by directly contacting the metal material with the dissimilar metal material, and the width of the contact between the metal material and the dissimilar metal material at the joint is 0.5 mm or more and 3 mm or less.

[0085] In the present invention, the metal material preferably has the form of a metal film.

[0086] In the present invention, the thickness of the metal film is preferably 0.05 mm or more and 5 mm or less.

[0087] In the present invention, the Group 5 metal is preferably at least one selected from the group consisting of vanadium, niobium, and tantalum.

[0088] In the present invention, the metal material containing the Group 5 element is preferably pure vanadium or a vanadium alloy.

[0089] In the present invention, the dissimilar metal material is preferably at least one selected from the group consisting of steel, stainless steel, and nickel-chromium-iron alloy.

[0090] (Effect) It is possible to provide a structure having a joint where a metal material containing a Group 5 element and a different metal material different from the metal material are joined, which can provide a good hydrogen separation function.

[0091] (Modes for Carrying Out the Invention) Preferred embodiments for carrying out the present invention will be described below. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. Furthermore, it goes without saying that the following embodiments may be modified as appropriate within the scope of the gist of the present invention.

[0092] The present invention provides a structure having a joint formed by joining a metallic material containing a Group 5 element to a dissimilar metallic material different from the metallic material. The metallic material is used to separate hydrogen from a hydrogen-containing mixed gas. The joint is formed by direct contact between the metallic material and the dissimilar metallic material, and the contact width between the metallic material and the dissimilar metallic material at the joint is 0.5 mm or more and 3 mm or less.

[0093] In the present invention, the joint is formed by directly contacting the metal material and the dissimilar metal material without using a third material (e.g., brazing filler metal) for joining the two materials. This makes it easier to prevent contamination of the joint surface by the third material and the third material from dissolving into the metal material, and also makes it less likely that hydrogen embrittlement will occur when hydrogen is extracted from a mixed gas or the like (when hydrogen diffuses through the metal material).

[0094] Furthermore, in the present invention, by ensuring the contact area (contact width between the metal material and the dissimilar metal material), the sealing performance between the metal material used to separate hydrogen from a hydrogen-containing mixed gas and the dissimilar metal material is ensured, making it easier to prevent leakage of hydrogen or the mixed gas from the joint. Furthermore, since the joint between the metal material and the dissimilar metal material is strong, the metal material is less likely to peel off from the dissimilar metal material that serves as the base material. As a result, when the dissimilar metal material is part of the housing of a hydrogen separation device, stable hydrogen separation is possible, making it easier to operate the hydrogen separation device for long periods of time.

[0095] The metal material of the present invention contains a Group 5 element. The metal material is used to separate hydrogen from a hydrogen-containing mixed gas. This is because metal materials containing a Group 5 element have excellent properties, such as the ability to selectively separate and transmit hydrogen from a mixed gas. The Group 5 element is preferably at least one selected from the group consisting of vanadium, niobium, and tantalum, with vanadium being more preferred. Group 5 elements, such as vanadium, particularly the so-called vanadium group elements, have similar chemical properties. Vanadium has the property of permeating hydrogen, so Group 5 elements other than vanadium, particularly vanadium group elements, also have similar properties. Although the present invention uses a Group 5 element for the metal membrane, as described above, Group 5 elements may be used in combination because their chemical properties are similar. For example, vanadium may coexist with niobium or tantalum, or an alloy thereof may be formed.

[0096] Furthermore, the metallic material of the present invention may contain elements other than Group 5 elements. The inclusion of such elements facilitates the imparting of various properties to the metallic material. Examples of such elements include iron (Fe), ruthenium (Ru), aluminum (Al), tungsten (W), molybdenum (Mo), chromium (Cr), and cobalt (Co). The use of these alloying elements facilitates the imparting of rigidity to metallic materials (e.g., hydrogen separation membranes) and suppresses the hydrogen solid solubility (also known as hydrogen solubility) in the alloy even when the applied hydrogen pressure is increased, thereby contributing to improved hydrogen embrittlement resistance. The content of elements other than Group 5 elements is typically 0.1 atomic % or more, preferably 1 atomic % or more, for each element. Within this range, the above-described properties are easily imparted to the metallic film. Meanwhile, the content of elements other than Group 5 elements is typically 50 atomic % or less, preferably 40 atomic % or less, and more preferably 11 atomic % or less, for each element. Within this range, the desired properties are easily imparted without diminishing the benefits of using Group 5 elements.

[0097] In the metal material of the present invention, in consideration of hydrogen permeability, it is preferable that the metal material containing a Group 5 element is pure vanadium or a vanadium alloy. In principle, pure vanadium refers to a metal material containing 100 atomic % vanadium. However, metal materials containing unavoidable impurities in vanadium are also included in the concept of "pure vanadium."

[0098] The content of Group 5 elements and other elements in metallic materials can be analyzed by the following method: using a scanning electron microscope equipped with an EDS or WDS (SEM / EDS / WDS) or a field emission scanning electron microscope (FE-SEM / EDS / WDS), the types and compositions of the contained elements can be analyzed by setting appropriate analytical conditions.

[0099] The metal material of the present invention preferably has the form of a metal film. In this case, the thickness of the metal film is preferably 0.05 mm or more. Generally, the thicker the metal film, the greater the mechanical strength, making it less susceptible to fracture and allowing hydrogen to permeate over a long period of time. On the other hand, increasing the thickness of the metal film tends to decrease the amount of hydrogen that can permeate per unit time. For this reason, the thickness of the metal film must be appropriately controlled. From the above perspectives, the thickness of the metal film is preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more, while typically 5 mm or less, preferably 1 mm or less. The thickness of the metal film may be measured using a known measuring device such as a finger, vernier caliper, micrometer, or 3D shape measuring device, depending on the thickness.

[0100] In the present invention, the metal material and dissimilar metal material have a joint. The "joint" refers to the interface between the metal material and dissimilar metal material, that is, the portion where the metal material and dissimilar metal material are joined. There are no particular limitations on the joining method, but in the present invention, welding is preferably used. This makes it easier to form a strong joint, ensuring mechanical strength, ensuring sealing properties, and suppressing hydrogen embrittlement. In the present invention, the joint is formed by direct contact between the metal material and dissimilar metal material. For this reason, welding is performed without using solder or brazing filler.

[0101] There are no particular limitations on the welding method. For example, there is pressure welding, which applies mechanical pressure to the joint between a metal material and a dissimilar metal material, and fusion welding, which heats the joint between a metal material and a dissimilar metal material to a temperature above the melting point to join them. Of these, fusion welding is preferred from an industrial perspective. Furthermore, among fusion welding methods, electron beam welding, laser welding, and TIG welding are preferred from the viewpoints of ensuring the mechanical strength of the joint, ensuring sealing properties, and suppressing hydrogen embrittlement. Furthermore, considering that thin plates such as hydrogen-permeable membranes are being welded, electron beam welding or laser welding is more preferred as the welding method. Furthermore, when using electron beam welding, it is preferable to perform welding in a vacuum. Welding in a vacuum makes it easier to suppress oxidation of the metal material or dissimilar metal material, thereby making it easier to suppress hydrogen embrittlement at the joint. Furthermore, when using laser welding, it is more preferable to use a solid-state laser from the viewpoint of achieving high-precision, high-density welding, and fiber welding using a fiber laser is preferred.

[0102] The detailed conditions for welding may be appropriately controlled from the viewpoints of ensuring the mechanical strength of the joint, ensuring sealing properties, and suppressing hydrogen embrittlement, with the aim of suppressing the generation of impurities or the incorporation of modified substances into the joint during welding.

[0103] In the present invention, the contact width between the metal material and the dissimilar metal material at the joint is set to 0.5 mm or more and 3 mm or less. Here, the "contact width between the metal material and the dissimilar metal material" is synonymous with the width of the joint between the metal material and the dissimilar metal material, and both terms are treated as synonymous in this specification. In addition, the contact width between the metal material and the dissimilar metal material at the joint is preferably determined by observing a cross section of the joint with a scanning electron microscope (SEM).

[0104] As described above, the term "joint" refers to the interface between a metal material and a dissimilar metal material, i.e., the portion where the metal material and the dissimilar metal material are joined. In practice, the metal material and the dissimilar metal material are brought into contact with each other, and then the contact portion is joined using the above-mentioned welding or the like to form the joint. The cross section of the joint is then observed, and the width of the joint between the two is set to the above-mentioned numerical range. Here, to observe the cross section of the joint, the structure of the present invention is cut to expose the cross section. Examples of cutting methods include mechanical machining, ion beam machining, etc. More specifically, mechanical polishing, microtome, FIB (Focused Ion Beam), ion polisher (CP), and liquid nitrogen cooling fracture can be mentioned. Among these, mechanical polishing after mechanical machining (wire electric discharge machining) is preferred from the viewpoint of enabling good observation of the cross section and the state of the joint.

[0105] When using a scanning electron microscope (SEM), observation with the SEM should be performed at a magnification that allows the joint to fit within the observation field and the width of the joint to be observed. The width of the joint observed within this observation field (the portion where the boundary between the metal material and the dissimilar metal material cannot be visually confirmed) should be measured appropriately. Scanning electron microscopes (SEMs) sold by analytical instrument manufacturers can be used appropriately. For example, the JSM-7100F manufactured by JEOL Ltd. can be used. When using this device, secondary electron images can be obtained at an accelerating voltage of 15 kV during SEM observation.

[0106] In the present invention, the contact width between the metal material and the dissimilar metal material at the joint is set to 0.5 mm or more and 3 mm or less. The reason for setting the width to 0.5 mm or more is to prevent defects such as peeling or tearing of the metal material containing a Group 5 element from the dissimilar metal material, taking into account the decrease in strength of the metal material containing a Group 5 element when separating hydrogen from a hydrogen-containing mixed gas. This will be explained using vanadium as the Group 5 element as an example. Hereinafter, in the explanation of the lower limit of the contact width between the metal material and the dissimilar metal material, significant figures may be used up to three digits.

[0107] Using a pure vanadium film as the metal material containing a Group 5 element, we assume that this film will be destroyed by shear deformation. First, we calculate the yield stress of the pure vanadium film from its Vickers hardness. It is generally known that there is a 1 / 3 relationship between Vickers hardness and yield stress. Since the Vickers hardness of pure vanadium is 120 HV (1180 MPa in MPa), the yield stress of the pure vanadium film is estimated to be approximately 400 MPa.

[0108] When a pure vanadium membrane with a diameter of 43 mm and a thickness of 0.3 mm is used, the area subjected to the shear stress acting on this membrane is 40.5 mm, which is the product of the circumference length of 135 mm (= 43 mm × π) and the membrane thickness of 0.3 mm. ２ If we consider shear stress to be the yield stress, the maximum load Patom that this membrane can withstand can be calculated from the yield stress and the area calculated above. Patom is then calculated as 1650 kgf (= 400 (MPa) x 40.5 (mm ２ ) / 9.8 (gravitational acceleration, unit: m / s ２ This value is the maximum load that the membrane can withstand under atmospheric pressure.

[0109] On the other hand, experiments have shown that when a pure vanadium membrane of the above shape is pressurized in a hydrogen atmosphere, it will break at a pressure difference of approximately 10 atmospheres. The load applied to the pure vanadium membrane at this time is PH = 148.0 kgf (= 1450 (membrane area, unit: mm ２ ) x 1 (pressure, unit: MPa) / 9.8 (gravitational acceleration, unit: m / s２ )). It can be seen that PH is a much lower value compared to Patom. This difference can be considered to be the effect of hydrogen embrittlement. Therefore, PH / Patom = 0.09 is defined as the coefficient RH that takes into account the effect of hydrogen embrittlement. Based on the above assumptions, the minimum weld width required between a pure vanadium film and a dissimilar metal material in a hydrogen atmosphere is calculated.

[0110] When operating a hydrogen permeation device using the above-mentioned pure vanadium membrane, the pressure difference between the primary side (input side, in other words, the side where a mixed gas containing hydrogen comes into contact with the pure vanadium membrane) and the secondary side (output side, in other words, the side where hydrogen is separated and permeates) is set to 0.3 MPa, in order to ensure stable operation without cracking the pure vanadium membrane. If a pure vanadium membrane with a diameter of 30 mm (when a stainless steel ring with an outer diameter of 52 mm and an inner diameter of 30 mm is welded concentrically to a pure vanadium membrane with an outer diameter of 43 mm, the diameter of the vanadium membrane subjected to pressure will be 30 mm) is used as the hydrogen separation membrane, its area will be 707 mm. ２ As mentioned above, the pressure difference between the primary side and the secondary side is set to 0.3 MPa, so the pressure difference for the pure vanadium membrane is 21.6 kgf (= 0.3 (pressure difference, unit: MPa) × 707 (membrane area, unit: mm ２ ) / 9.8 (gravitational acceleration, unit: m / s ２ )) load is applied.

[0111] Then, when welding a certain width of the pure vanadium film from a diameter of 30 mm inside, the minimum welding area required under atmospheric pressure is calculated. The minimum welding area in this case is calculated as follows: 21.6 (load, unit: kgf) x 9.8 (gravitational acceleration, unit: m / s ２ ) / minimum welding area = 400 (yield stress = shear strength, unit: MPa) is established. Therefore, the minimum welding area is 0.53 mm ２ (= 21.6 (load, unit: kgf) x 9.8 (gravitational acceleration, unit: m / s ２) / 400 (yield stress = shear strength, unit: MPa)). Calculating the minimum weld width from this minimum weld area, the circumference of a 30 mm diameter is 94.2 mm, so the required weld width in air is Latom = 0.0056 mm (= 0.53 (required cross-sectional area, unit: mm ２ ) / 94.2 (circumferential length, unit: mm)). By correcting this Latom with the correction factor mentioned above, the required weld width in a hydrogen atmosphere is obtained as LH = 0.06 mm (= 0.0056 (Latom, unit: mm) / 0.09 (RH, correction factor)).

[0112] As described above, when calculations are performed under certain assumptions, a weld width (bead width) of 0.06 mm is sufficient. If this is converted into the weld width of an actual welding device, the lower limit of the bead width (the width where the metal material and the dissimilar metal material are in contact) is 0.5 mm.

[0113] The width of the contact between the metallic material and the dissimilar metallic material is preferably 0.6 mm or more from the viewpoint of improving the mechanical strength of the joint. On the other hand, the wider the width of the contact between the metallic material and the dissimilar metallic material, the more preferable it is from the viewpoint of ensuring mechanical strength, but from the viewpoint of shortening the joining operation time and improving production efficiency, the width is preferably 2.5 mm or less, more preferably 2 mm or less.

[0114] In the present invention, the hardness of the joint generally tends to be softer than that of the non-jointed portion of the metal material (the portion of the base metal material). This is because the joint melts during welding, resulting in an effect similar to annealing. However, from the viewpoint of the strength of the film itself, the Vickers hardness of the joint is preferably 30 HV or more, more preferably 50 HV or more, and particularly preferably 60 HV or more.

[0115] On the other hand, the Vickers hardness of the non-joint portion (the portion of the base metal material) is preferably 80 HV or more. This range makes it easier to soften the metal material and ensure toughness. On the other hand, from the viewpoint of hardening the metal material and ensuring mechanical strength, the Vickers hardness is preferably 100 HV or more, more preferably 120 HV or more, particularly preferably 130 HV or more, and most preferably 150 HV or more. The Vickers hardness of metal materials is generally 500 HV or less, usually 300 HV or less. The Vickers hardness may be measured using a commercially available Vickers hardness tester (for example, a micro Vickers hardness tester (for example, the HM-100 series from Mitutoyo Corporation)).

[0116] The dissimilar metal material used in the present invention refers to a metal material containing a major element different from the major element constituting the metal material. There are no particular restrictions on this dissimilar metal material, but the dissimilar metal material often serves as a base material or substrate to support the metal material and also constitutes part of the housing of the hydrogen separation device. From this perspective, the dissimilar metal material is preferably at least one selected from the group consisting of steel, stainless steel, and a nickel-chromium-iron alloy. Furthermore, from the perspective of the housing of the hydrogen separation device, it is more industrially preferable that the dissimilar metal material be stainless steel.

[0117] [Modifications] While the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope of the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments.

[0118] (Examples) [Example 1] (Electron Beam Welding) A disk-shaped pure vanadium film with a diameter of 40 mm and a thickness of 0.3 mm was prepared as a metal material containing a Group 5 element. Meanwhile, a ring-shaped stainless steel plate with an outer diameter of 52 mm, an inner diameter of 30 mm, and a thickness of 0.5 mm was prepared as a dissimilar metal material. The two were then welded in a vacuum using an electron beam. Figure 18 shows a schematic diagram of an electron beam welding apparatus (left side) and a schematic diagram (right side) showing the metal material (vanadium film with a diameter of 40 mm) and the dissimilar metal material (ring-shaped stainless steel plate with a diameter of 52 mm and an inner diameter of 30 mm) placed on the workpiece during electron beam welding. Electron beam welding was performed under reduced pressure in the vacuum chamber of the electron beam welding apparatus shown in the left diagram of Figure 18. The conditions were as follows: Electron beam processing machine: EBM-6LB-1VR (manufactured by Mitsubishi Electric Corporation) Processing conditions: Cathode diameter φ2 mm, acceleration voltage 60 kV, W.D. 300 mm, beam current 15.5 mA

[0119] (SEM Observation of the Cross Section of the Joint) Three welded samples (n = 3) of the disk-shaped pure vanadium film and the ring-shaped stainless steel plate welded as described above were prepared, and the cross section of each weld (a test piece (cross section) was prepared by mechanically polishing after machining (wire electric discharge machine)) was observed with a scanning electron microscope (SEM). For SEM observation, a JSM-7100F manufactured by JEOL Ltd. was used to obtain a secondary electron image at an accelerating voltage of 15 kV.

[0120] The observation results are shown in Figure 19. Figure 19 shows SEM observation images of the cross sections of the joints in the three prepared samples. In the first sample (Figure 19(a)), the contact width between the metal material and the dissimilar metal material was 0.8 mm. In the second sample (Figure 19(b)), the contact width between the metal material and the dissimilar metal material was 1.1 mm. In the third sample (Figure 19(c)), the contact width between the metal material and the dissimilar metal material was 1.65 mm.

[0121] (Hydrogen permeation test) Figure 20 shows the measurement results of the hydrogen permeation performance of a sample (effective diameter of the membrane: 30 mm) in which a vanadium membrane was electron-beam welded to the center of the doughnut-shaped stainless steel ring (diameter: 52 mm) shown in Figure 18, and a normal vanadium membrane without this welding (the diameter of the vanadium membrane was 52 mm, but in order to compare with the electron-beam welded sample, the data obtained in the experiment was converted so that the effective diameter of the membrane was 30 mm). The hydrogen permeation test was carried out according to the following procedure.

[0122] A conventional vanadium film was subjected to RF sputtering treatment for 6 minutes at a substrate temperature of 300°C using an RF sputtering device, and both sides of the film were coated with Pd-25 mol% Ag to impart hydrogen dissociation catalytic properties.For the sample in which the vanadium film was electron beam welded to the center of the doughnut-shaped stainless steel ring shown in Figure 18, the vanadium film before welding was subjected to RF sputtering treatment for 6 minutes at a substrate temperature of 300°C using an RF sputtering device, and both sides of the film were coated with Pd-25 mol% Ag to impart hydrogen dissociation catalytic properties.

[0123] Fig. 21 is a schematic diagram of the experimental apparatus used in the hydrogen permeation test. In the area labeled "hydrogen-permeable membrane" in this schematic diagram, either (1) a sample (membrane effective diameter 30 mm) in which a vanadium membrane was electron-beam welded to the center of a doughnut-shaped stainless steel ring (diameter 52 mm) as shown in Fig. 18, or (2) a sample with a normal vanadium membrane, which had been RF sputtered, was placed. The entire apparatus was evacuated, and the amount of hydrogen permeated was measured with a flow meter while the mixed gas pressure on the primary side was appropriately adjusted.

[0124] When the samples (1) and (2) above were placed in the location marked "hydrogen-permeable membrane" in Figure 21, the vanadium membrane was exposed to the primary mixed gas from left to right. The hydrogen permeation test was conducted at a test temperature of 350°C, and the hydrogen gas supply pressure was in the range of 0.1 to 0.5 MPa abs. The hydrogen gas outlet pressure was controlled by vacuuming with a pump. In Figure 20, the vertical axis represents the hydrogen permeation rate per minute L (SLM), and the horizontal axis represents the hydrogen gas supply pressure on the input (primary) side.

[0125] The hydrogen permeation test for the above sample (1) was carried out using a sample welded under the same conditions as the above three prepared welded samples.

[0126] As can be seen from the graph in Figure 20, no cracks in the membrane or destruction or fracture of the welded joints occurred up to an absolute pressure of 0.5 MPa on the primary side. Regarding the amount of hydrogen permeation, it was possible to achieve good hydrogen permeation, similar to that of a normal vanadium membrane that is not welded.

[0127] [Example 2] (Fiber Welding) A disk-shaped pure vanadium film and a ring-shaped stainless steel plate, each of the same size as in Example 1, were prepared. Then, the two were joined by fiber welding. Figure 22 shows a schematic diagram of the fiber welding apparatus (left side) and a schematic diagram (right side) showing the metallic material (vanadium film, diameter 40 mm) and dissimilar metallic material (ring-shaped stainless steel plate, diameter 52 mm, inner diameter 30 mm) placed on the workpiece during fiber welding. Fiber welding was performed in the atmosphere under appropriately set welding conditions. Visual inspection and measurement of the cross section revealed that the contact width between the metallic material and the dissimilar metallic material was 1 to 2 mm.

[0128] (Hydrogen permeation test) A hydrogen permeation test was carried out in the same manner as in Example 1. Fig. 23 shows the measurement results of the hydrogen permeation performance of a sample (effective diameter of the membrane: 40 mm) in which a vanadium membrane was fiber-welded to the center of the doughnut-shaped stainless steel ring (diameter: 52 mm) shown in Fig. 22, and a normal vanadium membrane without this welding (the diameter of the vanadium membrane was 52 mm, but the data obtained in the experiment was converted so that the effective diameter of the membrane was 40 mm in order to compare with the electron-beam welded sample).

[0129] As can be seen from the graph in Figure 23, no cracks in the membrane or destruction or fracture of the welded joints occurred up to an absolute pressure of 0.5 MPa on the primary side of the input gas. Regarding the amount of hydrogen permeation, it was possible to achieve good hydrogen permeation, similar to that of a normal vanadium membrane that is not welded.

[0130] 3. Invention Related to Metallic Material Containing a Group 5 Element Hereinafter, as an invention according to one aspect of the present invention, a metallic material containing a Group 5 element and used to separate hydrogen from a hydrogen-containing mixed gas will be described (hereinafter in this section, the invention according to the above structure will be referred to as "the present invention"). This invention is based on Japanese Patent Application No. 2024-082065.

[0131] (Background Art) There is known technology relating to a hydrogen separation device that uses a hydrogen permeable membrane formed from an alloy primarily composed of a non-palladium (Pd)-based metal, such as a metal belonging to Group 5 of the elements, such as vanadium (V), niobium (Nb), or tantalum (Ta) (Patent Document 4).

[0132] (Problem to be solved)

[0133] In a hydrogen separation device that uses a hydrogen-permeable membrane (hereinafter sometimes referred to as a "metal membrane containing a Group 5 element") formed from a non-palladium (Pd)-based metal, for example, a metal belonging to Group 5 such as vanadium (V), niobium (Nb), or tantalum (Ta), or an alloy containing a non-palladium (Pd)-based metal as the main metal (hereinafter sometimes referred to as a "metal material containing a Group 5 element"), an issue to be addressed is how to increase the yield per unit time of hydrogen separated from a hydrogen-containing mixed gas.

[0134] The present invention was created in consideration of the above problems, and aims to provide a technology that makes it possible to increase the yield per unit time of hydrogen separated from a hydrogen-containing mixed gas.

[0135] (Means for Solving the Problem) One method for increasing the yield per unit time of hydrogen separated from a hydrogen-containing mixed gas is to increase the area of ​​the hydrogen-permeable membrane that comes into contact with the mixed gas. One possible method for increasing the area of ​​the hydrogen-permeable membrane is to increase the area by joining a metal membrane containing a Group 5 element by a method such as welding.

[0136] In this regard, in a report on welding vanadium membranes, a pipe-shaped alloy membrane with a diameter of 6 mm and a length of 80 mm was fabricated by rolling a 100 mm thick V-10%Fe alloy membrane into a cylindrical shape and welding it, and both ends of this pipe-shaped alloy membrane were joined with Swagelok joints to fabricate a pipe-shaped V alloy membrane cell. Using this cell, a hydrogen permeation test was conducted by introducing 0.4 MPa pure hydrogen gas into the primary side as the feed gas, and it was reported that 30 L / h of pure hydrogen was obtained by permeation (Non-Patent Document 1).

[0137] However, in Non-Patent Document 1, the primary pressure can only be increased to 0.4 MPa. Furthermore, the hydrogen permeation rate in Non-Patent Document 1 only reaches 30 L / h. Therefore, aiming to separate hydrogen at higher pressures, the inventors further investigated the applicability of welding to metal membranes containing Group 5 elements. They found that in order to improve the durability of a metal membrane containing Group 5 elements with welded joints, including the joints, it is important to ensure that the Group 5 element content ratios at the joints and other locations (hereinafter sometimes referred to as "non-jointed areas") are approximately the same. This is presumably because the incorporation of impurities or element segregation (i.e., uneven chemical composition at different locations) at the joints makes hydrogen embrittlement more likely to occur during hydrogen permeation.

[0138] The present invention has been made in view of the above.

[0139] The present invention relates to a metallic material containing a Group 5 element, which is used for separating hydrogen from a hydrogen-containing mixed gas, the metallic material having a bonded portion, and characterized in that when a bonded portion content, which is the content of the Group 5 element at the bonded portion, and a non-bonded portion content, which is the content of the Group 5 element in a portion of the metallic material other than the bonded portion, are each measured by SEM-EDX (energy dispersive X-ray spectroscopy), the bonded portion content / non-bonded portion content is in the range of 0.9 to 1.1.

[0140] In the present invention, the metal material preferably has the form of a metal film or a metal tube.

[0141] In the present invention, it is preferable that the thickness of the metal film or the wall thickness of the metal pipe is 0.05 mm or more and 5 mm or less.

[0142] In the present invention, the Group 5 metal is preferably at least one selected from the group consisting of vanadium, niobium, and tantalum.

[0143] In the present invention, the metal material containing the Group 5 element is preferably pure vanadium or a vanadium alloy.

[0144] (Effects of the Invention) A metal material containing a Group 5 element and having a joint, which can provide a good hydrogen separation function, can be provided.

[0145] (Modes for Carrying Out the Invention) Preferred embodiments for carrying out the present invention will be described below. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. Furthermore, it goes without saying that the following embodiments may be modified as appropriate within the scope of the gist of the present invention.

[0146] The metallic material of the present invention is used to separate hydrogen from a hydrogen-containing mixed gas, and contains a Group 5 element. The metallic material has a bonded portion. When the bonded portion content, which is the content of the Group 5 element in the bonded portion, and the non-bonded portion content, which is the content of the Group 5 element in the portion of the metallic material other than the bonded portion, are measured by SEM-EDX (energy dispersive X-ray spectroscopy), the bonded portion content / non-bonded portion content ratio is in the range of 0.9 to 1.1. That is, the present invention has found that it is preferable to control the content of the Group 5 element in the bonded portion (bonded portion content) and the content of the Group 5 element in the portion of the metallic material (base metallic material) other than the bonded portion (non-bonded portion content) so that they are substantially identical. By performing such control, the bonded portion and the non-bonded portion can be considered to be in almost the same state from the perspective of hydrogen permeation, minimizing the difference in hydrogen permeability and minimizing hydrogen embrittlement.

[0147] The metallic material of the present invention is used to separate hydrogen from a hydrogen-containing mixed gas. Specifically, the mixed gas contacts one surface of the metallic material, hydrogen diffuses from the mixed gas into the metallic material, and is released from the other surface, thereby allowing hydrogen to permeate the metallic material. Generally, hydrogen atoms diffuse faster in metals than other atoms, allowing hydrogen to be extracted by permeating the metallic material. The form of such a metallic material is not particularly limited, but it is preferably in the form of a metallic membrane or metallic tube. In the case of a metallic membrane, hydrogen can be separated from a mixed gas by permeating hydrogen from the front surface to the back surface of the membrane. In the case of a metallic tube, hydrogen can be separated from a mixed gas by permeating hydrogen from the outer surface of the cylindrical metallic tube to the inner surface of the cylindrical cylindrical tube, or from the inner surface of the cylindrical metallic tube to the outer surface of the cylindrical cylindrical tube. Furthermore, in the case of a metallic tube, either the top or bottom surface of the cylinder may be sealed with a metallic membrane containing the same Group 5 element. This means that either the top or bottom surface of the cylinder is covered with a metallic membrane containing the same Group 5 element (hereinafter referred to as a "metal membrane cap"). This allows hydrogen to permeate from the inner surface of the metal tube cylinder and the inner surface of the metal film lid to the outer surface of the cylinder and the outer surface of the metal film lid, or from the outer surface of the cylinder and the outer surface of the metal film lid to the inner surface of the metal tube cylinder and the inner surface of the metal film lid.

[0148] The metal material of the present invention contains a Group 5 element. This is because metal materials containing a Group 5 element have the excellent property of selectively separating and allowing hydrogen to permeate from mixed gases. Examples of metal materials containing a Group 5 element include non-palladium (Pd)-based metals, more specifically, Group 5 metals such as vanadium (V), niobium (Nb), and tantalum (Ta), or alloys primarily composed of non-palladium (Pd)-based metals. More specifically, at least one selected from the group consisting of vanadium, niobium, and tantalum is preferably used as the Group 5 element, with vanadium being even more preferred. Group 5 elements typified by vanadium, particularly so-called vanadium group elements, have similar chemical properties. Since vanadium has the property of permeating hydrogen, other Group 5 elements, particularly vanadium group elements, also have similar properties. Furthermore, although a Group 5 element is used in the metal membrane in the present invention, Group 5 elements may be used in combination because, as described above, their chemical properties are similar. For example, vanadium may be coexisted with niobium or tantalum, or an alloy thereof may be used.

[0149] Furthermore, the metallic material of the present invention may contain elements other than Group 5 elements. The inclusion of such elements facilitates the imparting of various properties to the metallic material. Examples of such elements include iron (Fe), ruthenium (Ru), aluminum (Al), tungsten (W), molybdenum (Mo), chromium (Cr), and cobalt (Co). The use of these alloying elements facilitates the imparting of rigidity to metallic materials (e.g., hydrogen separation membranes) and suppresses the hydrogen solid solubility (also known as hydrogen solubility) in the alloy even when the applied hydrogen pressure is increased, thereby contributing to improved hydrogen embrittlement resistance. The content of elements other than Group 5 elements is typically 0.1 atomic % or more, preferably 1 atomic % or more, for each element. Within this range, the above-described properties are easily imparted to the metallic film. Meanwhile, the content of elements other than Group 5 elements is typically 50 atomic % or less, preferably 40 atomic % or less, and more preferably 11 atomic % or less, for each element. Within this range, the desired properties are easily imparted without diminishing the benefits of using Group 5 elements.

[0150] In the metal material of the present invention, the metal material containing a Group 5 element is preferably pure vanadium or a vanadium alloy, taking into consideration the balance between hydrogen permeability and hydrogen embrittlement resistance. In principle, pure vanadium refers to a metal material containing 100 atomic % vanadium. However, metal materials containing unavoidable impurities in vanadium are also included in the concept of "pure vanadium."

[0151] The content of Group 5 elements and other elements in metallic materials can be analyzed by the following method: using a scanning electron microscope equipped with an EDS or WDS (SEM / EDS / WDS) or a field emission scanning electron microscope (FE-SEM / EDS / WDS), the types and compositions of the contained elements can be analyzed by setting appropriate analytical conditions.

[0152] When a metal film or metal tube is used as the metal material of the present invention, the thickness of the metal film or the wall thickness of the metal tube is preferably 0.05 mm or more. Generally, the thicker the metal film or the wall thickness of the metal tube, the greater the mechanical strength, making it less susceptible to fracture and allowing hydrogen to permeate over a long period of time. On the other hand, increasing the thickness of the metal film or the wall thickness of the metal tube tends to decrease the amount of hydrogen that can permeate per unit time. Therefore, the thickness of the metal film or the wall thickness of the metal tube must be appropriately controlled. From the above perspectives, the thickness of the metal film or the wall thickness of the metal tube is preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more, while typically 5 mm or less, preferably 1 mm or less. The thickness of the metal film or the wall thickness of the metal tube may be measured using a known measuring device, such as a finger, vernier caliper, micrometer, or 3D shape measuring device, depending on the thickness.

[0153] The metallic material of the present invention has a joint. The term "joint" refers to the interface between metallic materials, i.e., the portion where the metallic materials are joined together. The joining method is not particularly limited, but welding is preferably used in the present invention. From the viewpoint of making the content ratio of Group 5 elements in the joint and the non-joined portion approximately the same, that is, from the viewpoint of controlling the composition difference between the joint and the non-joined portion within a certain range, it is preferable to directly join the metallic materials together without using solder or brazing filler during welding.

[0154] There are no particular limitations on the welding method. Examples include pressure welding, which applies mechanical pressure to the joint between metal materials; fusion welding, which heats the joint between metal materials to a temperature above their melting points; and brazing, which melts a filler metal (solder or brazing filler) with a lower melting point than the metal materials to join them without melting them. Among these, pressure welding or fusion welding is preferred from the viewpoint of controlling the composition difference between the joint and non-joined portions within a certain range, and industrially, fusion welding is preferred. Furthermore, among fusion welding methods, electron beam welding, laser welding, and TIG welding are preferred from the viewpoint of controlling the composition difference between the joint and non-joined portions within a certain range. Furthermore, considering that thin plates such as hydrogen-permeable membranes are being welded, electron beam welding or laser welding is more preferred as the welding method. Furthermore, when using electron beam welding, it is preferable to perform welding in a vacuum. Welding in a vacuum makes it easier to control the composition difference between the joint and non-joined portions within a certain range. Furthermore, when laser welding is used, it is more preferable to use a solid-state laser, and it is preferable to use fiber welding using a fiber laser, from the viewpoint of realizing high-precision, high-density welding.

[0155] The detailed conditions for welding are appropriately controlled so that impurities do not produce modified products during welding, from the viewpoint of making the content ratio of Group 5 elements in the joint and non-joint parts approximately the same, in other words, from the viewpoint of controlling the composition difference between the joint and non-joint parts within a certain range.

[0156] In the present invention, when the bonded portion content, which is the content of the Group 5 element in the bonded portion, and the non-bonded portion content, which is the content of the Group 5 element in the portion of the metallic material other than the bonded portion, are measured by SEM-EDX (energy dispersive X-ray spectroscopy), the bonded portion content / non-bonded portion content is set to be in the range of 0.9 to 1.1.

[0157] Here, as described above, the term "joint" refers to the joint between metal materials, that is, the portion where the metal materials are joined together. Therefore, when elemental analysis is performed in the observation field using EDX (energy dispersive X-ray spectroscopy) while observing with an SEM (scanning electron microscope) to perform element mapping using SEM-EDX, the joint content can be measured by setting this observation field to the joint (the welded portion in the case of welding). On the other hand, "portions of the metal material other than the joint" literally refers to the portion of the metal material other than the joint, that is, the raw portion of the metal material that is not affected by welding or the like. Therefore, when measuring the non-joint content, the observation field using SEM-EDX (energy dispersive X-ray spectroscopy) can be set to a portion of the raw metal material that is far from the joint and is determined to be not affected by welding or the like.

[0158] The SEM-EDX (energy dispersive X-ray spectroscopy) analytical device may be one sold by an analytical instrument manufacturer. For example, analysis can be performed by using a JSM-7100F manufactured by JEOL Ltd. in combination with an x-act series manufactured by Oxford Instruments Ltd. The analytical conditions for SEM-EDX (energy dispersive X-ray spectroscopy) may be, for example, an acceleration voltage of 15 kV, an irradiation current of 13 nA, a working distance of 10 mm, and an accumulated number of frames of 100.

[0159] In the present invention, the bonded portion content / non-bonded portion content ratio is set to a range of 0.9 to 1.1. By controlling the bonded portion content relative to the non-bonded portion content (the content in the metal material in its elemental state) within this deviation range, the Group 5 element content ratio in the bonded portion and the non-bonded portion can be made approximately the same. Ideally, the Group 5 element content ratio in the bonded portion and the non-bonded portion is set to 1.0, i.e., the Group 5 elements in the bonded portion and the non-bonded portion are the same. However, Group 5 elements are easily oxidized, making it difficult to completely eliminate the inclusion of other elements, including oxygen, during welding. In consideration of the above, the lower limit of the bonded portion content / non-bonded portion content is set to 0.9 because, while the lower limit is 0.85 even when using a welding technique that introduces the most impurities during welding, a stricter standard is required to consider hydrogen embrittlement of the joined material. From the perspective of approximating the compositions of the bonded portion and the non-bonded portion, the bonded portion content / non-bonded portion content ratio is more preferably 0.93 or more, and even more preferably 0.95 or more. Furthermore, when an alloy of a Group 5 element and other elements is used as a metallic material, various variations in the alloy composition are possible. Taking such variations into consideration, the upper limit of the bonded portion content / non-bonded portion content ratio is set to 1.1. On the other hand, the bonded portion content / non-bonded portion content ratio is more preferably set to 1.07 or less, and even more preferably set to 1.05 or less.

[0160] EDX analysis varies from measurement to measurement, with a reported standard deviation (σ) of 2.53%. Therefore, assuming a Gaussian distribution of measurement variability, the ±3σ range, which includes 99.7% of the measurement data, is ±2.53 x 3 = ±7.59%. Therefore, even if the Group 5 element content ratio between the bonded and non-bonded portions is an ideal value of 1.0, the possibility of EDX analysis results varying between 0.9241 and 1.0759 cannot be denied. Therefore, from the perspective of this data measurement variability, it is preferable to control the SEM-EDX (energy dispersive X-ray spectroscopy) analysis value within a ±10% range. A preferred range is ±8%. This indicates that if the analysis value is within the range of 0.9241 to 1.0759, it can be considered that the bonded portion is virtually free of impurities.

[0161] In the present invention, the hardness of the bonded portion generally tends to be softer than that of the non-bonded portion (the portion of the base metal material). This is thought to be because the bonded portion melts during welding, resulting in an effect similar to annealing. However, from the viewpoint of the strength of the film itself, the Vickers hardness of the bonded portion is preferably 30 HV or higher, more preferably 50 HV or higher, even more preferably 60 HV or higher, and particularly preferably 70 HV or higher.

[0162] On the other hand, the Vickers hardness of the non-joint portion (the portion of the base metal material) is preferably 80 HV or more. This range makes it easier to soften the metal material and ensure toughness. On the other hand, from the viewpoint of hardening the metal material and ensuring mechanical strength, the Vickers hardness is preferably 100 HV or more, more preferably 120 HV or more, particularly preferably 130 HV or more, and most preferably 150 HV or more. The Vickers hardness of metal materials is generally 500 HV or less, usually 300 HV or less. The Vickers hardness may be measured using a commercially available Vickers hardness tester (for example, a micro Vickers hardness tester (for example, the HM-100 series from Mitutoyo Corporation)).

[0163] [Modifications] While the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope of the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments.

[0164] (Examples) [Example 3] (Electron beam welding) Two 0.3 mm thick pure vanadium films (plates) were prepared as metal materials containing a Group 5 element, and these were welded with an electron beam. Figure 24 is a schematic diagram of an electron beam welding apparatus and a schematic diagram showing the state of two vanadium films (plates) placed on the workpiece during electron beam welding. Electron beam welding was carried out with the vacuum chamber of the electron beam welding apparatus shown in the left diagram of Figure 24 reduced in pressure. The conditions were as follows: Electron beam processing machine: EBM-6LB-1VR (manufactured by Mitsubishi Electric Corporation) Processing conditions: cathode diameter φ2 mm, acceleration voltage 60 kV, W.D. 300 mm, beam current 35.0 mA

[0165] (Vickers hardness) The Vickers hardness of the welded joint and non-jointed joint (the raw part of the metal material not affected by welding) was measured. As a result, the Vickers hardness of the welded joint was 90 HV, and the Vickers hardness of the non-jointed joint was 120 HV. The Vickers hardness was measured as follows.

[0166] A micro Vickers hardness tester (model number: HM-102) manufactured by Mitutoyo Corporation was used. The Vickers hardness test involves pressing a pyramidal diamond indenter against the sample, observing the resulting indentation under a microscope, and measuring the length of the diagonal to determine the hardness. The Vickers hardness test is excellent for measuring the hardness of thin samples, as the indentation is small, at a maximum of 1 mm or less. The measurement was also carried out by polishing the measurement surface of the sample.

[0167] (SEM Observation of Bonded and Non-Bonded Portions) The bonded and non-bonded portions were observed with an SEM. For the SEM observation, a JSM-7100F manufactured by JEOL Ltd. was used to acquire secondary electron images at an acceleration voltage of 15 kV. The observation results are shown in FIG. 25. FIG. 25 shows photographs of the SEM observation fields of the non-bonded portion (secondary electron image labeled "inside non-bonded portion" in FIG. 25) and the bonded portion (secondary electron image labeled "inside bonded portion" in FIG. 25). As can be seen from the figure, there is no difference between the bonded and non-bonded portions when observed visually.

[0168] (SEM-EDX (energy dispersive X-ray spectroscopy) measurement of bonded and non-bonded portions) SEM-EDX measurement of bonded and non-bonded portions was carried out. For the measurement, a JSM-7100F manufactured by JEOL Ltd. and an x-act series manufactured by Oxford Instruments Ltd. were used. The analysis conditions for SEM-EDX (energy dispersive X-ray spectroscopy) were an acceleration voltage of 15 kV, an irradiation current of 13 nA, a working distance of 10 mm, and an accumulated number of frames of 100.

[0169] The elemental mapping results of the joint (welded portion) were as follows: V: 98.2 mass %, O: 0.8 mass %, C: 0.9 mass %, Si: 0.1 mass %, and N and Al were not detected.

[0170] The elemental mapping results for the non-bonded portion were as follows: V: 97.6 mass %, O: 1.3 mass %, C: 1.0 mass %, Si: 0.1 mass %, and N and Al were not detected.

[0171] From the above, the ratio of the content of vanadium (V), which is a Group 5 element, that is, the content in the bonded portion / the content in the non-bonded portion, was 1.01 (a deviation of 1%).

[0172] 26 shows the results of measuring the hydrogen permeability of the vanadium membrane (cut into a disk-shaped membrane with a diameter of 52 mm) whose center was electron beam welded in Example 3 and a normal vanadium membrane (a disk-shaped membrane with a diameter of 52 mm) that was not welded, as well as a schematic diagram of the measurement sample (vanadium membrane whose center was electron beam welded) used in the measurement. The hydrogen permeation test was performed according to the following procedure.

[0173] The vanadium film with the center electron beam welded and the normal vanadium film were subjected to RF sputtering treatment at a substrate temperature of 300°C for 6 minutes using an RF sputtering device, and both sides of the film were coated with Pd-25 mol% Ag to impart hydrogen dissociation catalytic properties.

[0174] A schematic diagram of the experimental apparatus used in the hydrogen permeation test is shown in Figure 21. In the location labeled "hydrogen permeable membrane" in this schematic diagram, either (1) a vanadium membrane with an electron beam welded center that had been RF sputtered or (2) a standard vanadium membrane was placed. The entire apparatus was evacuated, and the amount of hydrogen permeated was measured with a flow meter while the pressure of the mixed gas on the primary side was appropriately adjusted.

[0175] When the vanadium membrane with its center electron-beam welded was placed in the location marked "hydrogen-permeable membrane" in Figure 21, the electron-beam weld shown on the right side of Figure 26 was set so that it was perpendicular to the flow of the primary mixed gas (in other words, the primary mixed gas was exposed from left to right to the vanadium membrane with its center electron-beam welded). The hydrogen permeation test was conducted at a test temperature of 350°C, and the hydrogen gas supply pressure was in the range of 0.1 to 0.7 MPa abs. The hydrogen gas outlet pressure was controlled by vacuuming with a pump. In Figure 26, the vertical axis represents the hydrogen permeation rate per minute L (SLM), and the horizontal axis represents the hydrogen gas supply pressure on the input (primary) side.

[0176] As can be seen from the graph in Figure 26, there is no difference in hydrogen permeability between electron-beam welded vanadium membranes and non-electron-beam welded (normal vanadium membranes with no joints) up to an absolute pressure of 0.5 MPa on the primary side. However, in the non-electron-beam welded (normal vanadium membranes with no joints) membrane, cracks occurred when the absolute pressure of the primary side gas reached around 0.55 MPa. On the other hand, the electron-beam welded vanadium membrane was able to achieve good hydrogen permeation without any cracks up to an absolute pressure of 0.7 MPa on the primary side.

[0177] Furthermore, the electron beam welded vanadium membrane has a primary gas absolute pressure of 0.7 MPa and a secondary gas flow rate (Outlet gas flow rate, Q) of 1.65 SLM. 1.65 SLM means 1.65 L / min, which means that a hydrogen permeation rate of 99 L / h was achieved. Considering that the hydrogen permeation rate in Non-Patent Document 1 was only about 30 L / h, this means that the present invention has achieved a hydrogen permeation rate more than three times that of the prior art.

[0178] Using the apparatus shown in Figure 21, the durability of the electron beam welded vanadium film was confirmed under conditions of a primary gas absolute pressure of 0.2 MPa and a test temperature of 350°C. As a result, even after operating the apparatus continuously for 60 hours, no cracking of the electron beam welded vanadium film was observed.

[0179] [Example 4] (Fiber welding) Two 0.3 mm thick pure vanadium films (plates) were prepared as metal materials containing a Group 5 element and were welded with an electron beam. Figure 27 is a schematic diagram of the fiber welding device and a schematic diagram showing the appearance of two vanadium films (plates) placed on the workpiece during fiber welding. Fiber welding was performed in the atmosphere under appropriately set welding conditions.

[0180] (Vickers Hardness) The Vickers hardness of the welded joint and the non-jointed joint (the bare part of the metal material not affected by welding) was measured in the same manner as in Example 3. As a result, the Vickers hardness of the welded joint was 90 HV, and the Vickers hardness of the non-jointed joint was 140 HV.

[0181] (SEM-EDX (energy dispersive X-ray spectroscopy) measurement of bonded and non-bonded portions) SEM-EDX measurement of bonded and non-bonded portions was carried out in the same manner as in Example 3. As a result, the element mapping results of the bonded (welded) portions were as follows: V: 93.8 mass % O: 4.2 mass % C: 1.3 mass % Al: 0.7 mass % (presumably derived from the vanadium raw material) Si: 0.1 mass % No N was detected.

[0182] The elemental mapping results for the non-bonded portion were as follows: V: 92.4 mass %, O: 5.6 mass %, C: 1.3 mass %, Al: 0.7 mass % (presumably derived from the vanadium raw material), Si: 0.1 mass %, and no N was detected.

[0183] From the above, the ratio of the content of vanadium (V), which is a Group 5 element, that is, the content in the bonded portion / the content in the non-bonded portion, was 1.02 (a deviation of 2%).

[0184] (Hydrogen Permeation Test) A hydrogen permeation test was conducted in the same manner as in Example 3. FIG. 28 shows the results of measuring the hydrogen permeation performance of the vanadium membrane (disk-shaped membrane with a diameter of 52 mm) fiber-welded at the center in Example 4 and a regular vanadium membrane (disk-shaped membrane with a diameter of 52 mm) without this welding. For the vanadium membrane fiber-welded at the center, a sample with the same shape as in Example 3 was used for the measurement. As can be seen from the graph in FIG. 28, the hydrogen permeation test was successfully conducted on the vanadium membrane fiber-welded up to an absolute gas pressure of more than 0.4 MPa and 0.5 MPa on the primary side. In Example 4, even the vanadium membrane without fiber welding (regular membrane with no joints) did not experience the phenomenon of membrane cracking up to an absolute gas pressure of 0.5 MPa on the primary side. However, the results showed that the vanadium membrane with fiber welding generally had better hydrogen permeation performance than the vanadium membrane without fiber welding (regular membrane with no joints).

[0185] Furthermore, the fiber-welded vanadium membrane has a primary gas absolute pressure of 0.5 MPa and a secondary gas flow rate (Outlet gas flow rate, Q) of 1.6 SLM. 1.6 SLM means 1.6 L / min, which means that a hydrogen permeation rate of 96 L / h was achieved. Considering that the hydrogen permeation rate in Non-Patent Document 1 was only about 30 L / h, this means that the present invention has achieved a hydrogen permeation rate more than three times that of conventional technology.

[0186] Using the apparatus shown in Figure 21, the durability of the fiber-welded vanadium membrane was confirmed under conditions of a primary gas absolute pressure of 0.2 MPa and a test temperature of 350°C. As a result, even after operating the apparatus continuously for 60 hours, no cracking of the fiber-welded vanadium membrane was observed.

[0187] [Example 5] (TIG welding) Two 0.2 mm thick pure vanadium films (plates) were prepared as metal materials containing Group 5 elements and were TIG-welded (arc welding using a tungsten electrode and inert gas). The placement on the workpiece and the welding locations during welding were the same as in Examples 3 and 4.

[0188] (SEM-EDX (energy dispersive X-ray spectroscopy) measurement of bonded and non-bonded portions) As in Example 3, SEM-EDX measurement of bonded and non-bonded portions was carried out. As a result, the elemental mapping results of the bonded (welded) portions were as follows: V: 96.62 mass % C: 3.38 mass %

[0189] The elemental mapping results for the non-bonded portion were as follows: V: 89.04 mass %, C: 10.79 mass %, Si: 0.17 mass %

[0190] From the above, the ratio of the content of vanadium (V), which is a Group 5 element, that is, the content in the bonded portion / the content in the non-bonded portion, was 1.085 (8.5% deviation).

[0191] The present invention provides a hydrogen separation device that can easily suppress leakage of mixed gas or hydrogen gas from the end of a hydrogen permeation section and can achieve miniaturization of the device. One aspect of the present invention provides a structure having a joint where a metal material containing a Group 5 element and a dissimilar metal material different from the metal material are joined, and the metal material can provide good hydrogen separation function. Another aspect of the present invention provides a metal material containing a Group 5 element and having a joint, which can provide good hydrogen separation function.

[0192] 100, 200, 300: Hydrogen separation unit 110, 210, 310: Storage chamber 120, 221, 222, 320: Collection chamber 130, 231, 232, 330: Hydrogen permeation section 140, 241, 242, 340: Boundary wall 150, 250, 350: Supply pipe 151, 251, 351: Discharge pipe 160, 261, 262, 360: Collection pipe 170, 271, 272: Ring 370: Joint 380: Welded part 390: Catalyst

Claims

1. A hydrogen separation device that separates and extracts hydrogen from a mixed gas containing hydrogen, comprising a hydrogen separation unit having a storage chamber to which the mixed gas is supplied, a collection chamber from which hydrogen is separated and extracted, and a boundary section separating the storage chamber and the collection chamber, and wherein a plurality of hydrogen permeation sections that can extract the hydrogen from the mixed gas are joined to the boundary section of the hydrogen separation unit by welding.

2. The hydrogen permeation rate per unit volume in the hydrogen separation unit is 2.5 x 10 －６ (L / min.mm ３ 2. The hydrogen separation device according to claim 1, wherein the hydrogen separation temperature is 1000° C. or more.

3. The hydrogen separation device according to claim 1, wherein the hydrogen separation unit is replaceable.

4. The hydrogen separation device according to claim 1, wherein the pressure applied to the hydrogen permeation section is 200 kPa or less absolute.

5. The hydrogen separation device according to claim 1, wherein two or more hydrogen permeation sections are provided at the boundary section as the plurality of hydrogen permeation sections.

6. A hydrogen separation device according to claim 1, wherein a plurality of holes are provided in the boundary portion, the hydrogen permeable portion is provided as a thin film so as to cover the plurality of holes, and the edge of the thin film is welded to the boundary portion.

7. The hydrogen separation device according to claim 6, wherein the thickness of the thin film is 0.05 mm or more and 5 mm or less.

8. A hydrogen separation device as described in claim 1, wherein a plurality of holes are provided in the boundary portion, and a plurality of the hydrogen permeation portions formed on the cylinder are inserted into the boundary portion and welded so that the side of the cylinder contacts the inner circumference of each of the plurality of holes.

9. The hydrogen separation device according to claim 8, wherein the cylindrical wall thickness is 0.05 mm or more and 5 mm or less.

10. The hydrogen separation device according to claim 1, wherein the hydrogen permeable portion contains a Group 5 element.

11. The hydrogen separation device according to claim 1, wherein the hydrogen permeation portion has a configuration in which a metal containing a Group 5 element is adhered to a porous substrate.

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