Hydrogen separation apparatus

Abstract

To inhibit leakage of a mixed gas or hydrogen from an end of a hydrogen permeation membrane in a hydrogen separation apparatus while downsizing the apparatus.SOLUTION: A hydrogen separation apparatus for separating and extracting hydrogen from a mixed gas containing hydrogen includes a hydrogen separation unit 100 having a housing chamber 110 to which the mixed gas is supplied, a collection chamber 120 for separating and extracting hydrogen, and a boundary portion separating the housing chamber 110 and the collection chamber 120, wherein a plurality of hydrogen permeation portions 130 capable of extracting hydrogen from the mixed gas are joined by welding to the boundary portion of the hydrogen separation unit 100.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for separating and extracting hydrogen from a mixed gas containing hydrogen. [Background technology]

[0002] 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 in order to increase the yield of hydrogen separated per unit time from a hydrogen-containing mixed gas. 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 (Patent Document 1). Another hydrogen separation device uses a hydrogen separation metal membrane 2 divided into four sections in order to reduce its size (Patent Document 2).

[0003] 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 addition, in Patent Document 2, each hydrogen separation metal membrane is sandwiched between a frame member and a support plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-13901 A (Claim 1, paragraph 0038, Figure 4) [Patent Document 2] JP 2008-253984 A (paragraphs 0072 to 0074, Figure 11) Summary of the Invention [Problem to be solved by the invention]

[0005] 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 from a mechanical design perspective. 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.

[0006] 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. [Means for solving the problem]

[0007] 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.

[0008] 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 is preferable.

[0009] In the present invention, it is preferable that the hydrogen separation unit is replaceable.

[0010] In the present invention, the pressure applied to the hydrogen permeable portion is preferably an absolute pressure of 200 kPa or less.

[0011] In the present invention, it is preferable that the plurality of hydrogen permeable portions are provided at two or more locations in the boundary portion.

[0012] 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.

[0013] In the present invention, the thickness of the thin film is preferably 0.05 mm or more and 5 mm or less.

[0014] 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.

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

[0016] In the present invention, the hydrogen permeable portion is preferably formed of a metal film containing a Group 5 element.

[0017] 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. [Effects of the Invention]

[0018] 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. [Brief explanation of the drawings]

[0019] [Figure 1]FIG. 1 is a perspective view showing an example of a hydrogen separation unit 100 according to a first embodiment. [Figure 2] 2 is a cross-sectional view (vertical cross-section) taken along line AA of the hydrogen separation unit 100 shown in FIG. 1, as viewed from the direction of the arrow indicated by A in FIG. [Figure 3] 2 is a cross-sectional view (vertical cross-section) taken along the line A1-A1 of the hydrogen separation unit 100 shown in FIG. 1, as viewed from the direction of the arrow indicated by A1 in FIG. [Figure 4] FIG. 3 is an enlarged view of the area enclosed by the dotted square line in FIG. 2. [Figure 5] FIG. 2 is a perspective view showing a state in which the top cover of the accommodation chamber of the hydrogen separation unit 100 shown in FIG. 1 has been removed. [Figure 6] FIG. 1 is a diagram illustrating an example of a method for extracting hydrogen from a mixed gas. [Figure 7] FIG. 10 is a perspective view showing an example of a hydrogen separation unit 200 according to a second embodiment. [Figure 8] 8 is a cross-sectional view (vertical cross section) of the hydrogen separation unit 200 shown in FIG. 7 taken along the line B--B as viewed from the direction of the arrow indicated by B in FIG. [Figure 9] 8 is a B1-B1 cross-sectional view (vertical cross-section) of the hydrogen separation unit 200 shown in FIG. 7, seen from the direction of the arrow indicated by B1 in FIG. 6. [Figure 10] FIG. 8 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. [Figure 11] FIG. 10 is a perspective view showing an example of a hydrogen separation unit 300 according to a third embodiment. [Figure 12] 11 is a CC cross-sectional view (vertical cross-section) of the hydrogen separation unit 300 shown in FIG. 11, seen from the direction of the arrow indicated by C in FIG. [Figure 13] 12 is a perspective view showing a boundary wall 340 to which a plurality of cylindrically formed hydrogen permeation sections 330 are welded, taken out from the hydrogen separation unit 300 shown in FIG. [Figure 14] 13 is an enlarged cross-sectional view of the portion surrounded by the dotted line in FIG. 12. FIG. [Figure 15]10 shows an example of a manufacturing process for the hydrogen permeable portion 330 used in the third embodiment. [Figure 16] 10 is an example of a manufacturing process for welding the hydrogen permeation portion 330 to the boundary wall 340 in the third embodiment. [Figure 17] FIG. 10 is a schematic diagram showing a state in which a catalyst 390 is applied to the surface of a hydrogen permeation portion 330 in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] The hydrogen separation device of the present invention is a device 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 joined to the boundary of the hydrogen separation unit by welding. 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 joining the hydrogen permeable section to the boundary by welding, leakage of the mixed gas or hydrogen gas is easily suppressed. Furthermore, by providing a plurality of hydrogen permeable sections at the boundary capable of extracting hydrogen from the mixed gas, the yield of hydrogen that can be separated or extracted per unit time can be increased.

[0022] From the viewpoint of miniaturization, the hydrogen permeation rate per unit volume of 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 (1 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 3×10 -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 ) or more. However, 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.

[0023] 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 have multiple membrane modules (multiple collection chambers, so to speak) inside 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.

[0024] 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.

[0025] In the present invention, multiple hydrogen permeation sections are welded to the boundaries of the hydrogen separation unit, making it 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 is 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).

[0026] 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.

[0027] 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.

[0028] 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.

[0029] [First embodiment] (Hydrogen separation unit) FIG. 1 is a perspective view showing an example of a hydrogen separation unit 100 according to the first embodiment. FIG. 2 is an AA cross-sectional view (vertical cross-section) of the hydrogen separation unit 100 shown in FIG. 1, seen 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, seen from the direction of the arrow indicated by A1 in FIG. 1. FIG. 4 is an enlarged view of the part 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.

[0030] 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 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 welded to the boundary wall 140, covering the holes. 2 and 3, for the sake of convenience, the hydrogen permeable sections 130a-130g and the boundary wall 140 are depicted as having the same thickness. However, in reality, the hydrogen permeable sections 130a-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-130g.

[0031] 2, 3, and 4, the ends of the hydrogen permeable portions 130a-130g are welded to the boundary wall 140 via rings 170a-170g. The rings 170a-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-130g are placed on the inner peripheral portions of the rings 170a-170g that are not welded to the boundary wall 140. The rings 170a-170g are then welded to the hydrogen permeable portions 130a-130g. By welding the hydrogen permeable portions 130a-130g to the rings 170a-170g, each hole in the boundary portion is sealed.

[0032] 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.

[0033] 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 that is sufficient to prevent gas leakage and ensure mechanical strength. The rings 170a to 170g are also made of stainless steel. The supply pipe 150, the discharge pipe 151, and the collection pipe 160 are also made of stainless steel.

[0034] 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 a metal film containing a Group 5 element has the excellent property of selectively separating and allowing hydrogen to permeate from a mixed gas. The Group 5 element is preferably at least one selected from the group consisting of vanadium, niobium, and tantalum, and vanadium (pure vanadium) is more preferably used. Group 5 elements typified by vanadium, particularly 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. In the present invention, a Group 5 element is used for the metal film. However, because Group 5 elements have similar chemical properties as described above, they may be used in combination. For example, vanadium may coexist with niobium or tantalum, or an alloy thereof may be formed.

[0035] Furthermore, the metal membrane 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). This suppresses the hydrogen solid solubility (also known as hydrogen solubility) in the alloy even under increased hydrogen pressure, 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. 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 benefits of using a Group 5 element are not diminished and the required properties can be easily imparted.

[0036] 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 equipped with EDS or WDS (SEM / EDS / WDS) or a field emission scanning electron microscope (FE-SEM / EDS / WDS), the types and compositions of contained elements can be analyzed by setting appropriate analytical conditions.

[0037] 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, the thicker the hydrogen permeable sections 130a-130g (hydrogen separation membranes), the smaller 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. It is generally set to 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.

[0038] In the present invention, the Vickers hardness of the hydrogen permeable sections 130a-130g (hydrogen separation membranes) is preferably 80 HV or higher. This range makes it easier to soften the hydrogen permeable sections 130a-130g (hydrogen separation membranes) and ensure toughness. On the other hand, from the perspective of hardening the hydrogen permeable sections 130a-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, Group 5 elements, particularly vanadium group elements, have similar chemical properties) is used for the hydrogen permeable sections 130a-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)).

[0039] The ends of the hydrogen permeable sections 130a-130g are joined by welding to rings 170a-170g that are 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 disc-shaped hydrogen permeable portions 130a-130g and the rings 170a-170g near the outer periphery of the disc-shaped hydrogen permeable portions 130a-130g is preferably 2% or more, more preferably 5% or more, of the diameter of the disc-shaped hydrogen permeable portions 130a-130g, while it is preferably 15% or less, more preferably 10% or less, of the diameter of the disc-shaped hydrogen permeable portions 130a-130g.

[0040] 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 this 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, and fiber welding using a fiber laser is preferable, from the perspective of achieving high-precision, high-density welding. Furthermore, TIG welding has the advantage of being easy to weld, requiring little labor, and low cost on an industrial scale.

[0041] (Hydrogen separation device) Next, a hydrogen separation device equipped with a hydrogen separation unit 100 will be described. Since the hydrogen separation unit 100 is preferably heated during use 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 device. The operation of this hydrogen separation device will be described below, 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.

[0042] First, in the initial stage, the heater is operated to heat the hydrogen separation unit 100 and raise the temperature of the hydrogen separation unit 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 allow it to exhibit its hydrogen separation function. Next, a mixed gas sent from an external mixed gas supply device (not shown) is flowed into the storage chamber 110 through the supply pipe 150 (step S1).

[0043] 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 part of the hydrogen contained in the mixed gas that flows 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 discharge 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 while controlling the pressure on the hydrogen permeation sections 130a-130g to an absolute pressure of 200 kPa or less. This control ensures a sufficient hydrogen permeation rate per unit volume (the yield of hydrogen that can be separated or extracted per unit time) while extending the replacement life of the hydrogen separation unit 100.

[0044] Meanwhile, the hydrogen extracted into the collection chamber 120 is sent to the outside through the collection pipe 160 (step S4). Then, the separated hydrogen is collected in an external storage tank (not shown).

[0045] According to the first embodiment, the hydrogen permeable sections 130a-130g are provided in seven locations, and these sections 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. This facilitates downsizing of the hydrogen separation unit 100. Based on the above, the hydrogen permeable sections 130a-130g are provided in seven locations, which increases the amount of hydrogen 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 as 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, allowing the hydrogen separation unit 100 to be operated stably for a long period of time. The absolute pressure is measured using a pressure sensor (not shown) installed in the piping (supply pipe 150).

[0046] 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.

[0047] [Second embodiment] (Hydrogen separation unit) Fig. 7 is a perspective view showing an example of a hydrogen separation unit 200 according to the second embodiment. Fig. 8 is a BB cross-sectional view (vertical cross-section) of the hydrogen separation unit 200 shown in Fig. 7, seen from the direction of the arrow indicated by B in Fig. 7. Fig. 9 is a B1-B1 cross-sectional view (vertical cross-section) of the hydrogen separation unit 200 shown in Fig. 7, seen from the direction of the arrow indicated by B1 in Fig. 7. Fig. 10 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.

[0048] 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 (some not shown, same below) and 232a-232g and the boundary walls 241, 242 are drawn to have the same thickness, but as in the first embodiment, the hydrogen permeable portions 231a-231g and 232a-232g are actually thin films, and therefore the boundary walls 241, 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 (some not shown, same below) form a first boundary portion (upper boundary portion), and the boundary wall 242 and the rings 272a-272g form a second boundary portion (lower boundary portion).

[0049] The hydrogen separation unit 200 has a generally disk-shaped appearance. The hydrogen separation unit 200 has collection chambers 221 and 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 to 231g are provided as thin films via rings 271a to 271g to cover the holes. Furthermore, the ends of the hydrogen permeation sections 231a to 231g are joined by welding to the rings 271a to 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-232g are provided as thin films via rings 272a-272g to cover the holes. Furthermore, the ends of the hydrogen permeable portions 232a-232g are joined by welding to the rings 272a-272g that form the boundary portion (second boundary portion).

[0050] 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.

[0051] 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-231g and 232a-232g may be the same as those of the first embodiment. The positional relationship between the rings 271a-271g and 272a-272g and the boundary walls 241 and 242, and the positional relationship between the rings 271a-271g and 272a-272g and the hydrogen permeable portions 231a-231g and 232a-232g may also be the same as those of the first embodiment. Similarly, the welding of the ends of the hydrogen permeable portions 231a-231g and 232a-232g may also be the same as those of the first embodiment.

[0052] (Hydrogen separation device) Next, a hydrogen separation device 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 device functions as a hydrogen separation device. Below, the operation of this hydrogen separation device, 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 sections 231a-231g and 232a-232g use metal membranes containing a Group 5 element, as in the first embodiment.

[0053] First, in the initial 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).

[0054] When the mixed gas flows into the storage chamber 210 and the pressure in the storage chamber 210 reaches a predetermined level, hydrogen contained in the mixed gas permeates through the hydrogen permeation sections 231a-231g provided in the boundary wall 241 and moves to the collection chamber 221, and also permeates through the hydrogen permeation sections 232a-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 has flowed into the storage chamber 210 permeates through the metal membranes containing a Group 5 element, which are the hydrogen permeation sections 231a-231g, and moves to the collection chamber 221. In addition, all or a portion of the hydrogen contained in the mixed gas that has flowed into the storage chamber 210 permeates through the metal membranes containing a Group 5 element, which are the hydrogen permeation sections 232a-232g, and moves to the collection chamber 222. The remaining mixed gas from which hydrogen has been separated is 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 permeation sections 231a-231g, 232a-232g 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 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).

[0055] 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).

[0056] 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 to the collection chambers 221, 222 from both the top and bottom of the storage chamber 210. This allows a greater amount of hydrogen to be extracted.

[0057] [Third embodiment] (Hydrogen separation unit) In the present invention, it is also preferable that a plurality of holes be provided at the boundary of the hydrogen separation unit, and that a plurality of hydrogen permeation sections formed on the cylinder be inserted into the boundary 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 while also making it easy to miniaturize the hydrogen separation unit and, in turn, the hydrogen separation device. An example of an embodiment utilizing this design is described below.

[0058] 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 in FIG. 11. FIG. 13 is a perspective view showing a boundary wall 340, to which multiple cylindrical 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.

[0059] 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 a mixed gas is supplied, and a collection chamber 320 are separated by a boundary wall 340. One end (bottom) of the cylindrical hydrogen permeation section 330a is closed, and the other end (top) of the cylindrical hydrogen permeation section 330a is inserted into a hole provided in the boundary wall 340, and the side surface of the top end of the cylinder is welded and joined to the boundary wall 340 via a joint 370a. Similarly, one end (bottom) of the cylindrical hydrogen permeation section 330b is closed, and the other end (top) of the cylindrical hydrogen permeation section 330b is inserted into a hole provided in the boundary wall 340, and the side surface of the top end of the cylinder is welded and joined to the boundary wall 340 via a joint 370b. The hydrogen permeation sections 330c to 330g have the same structure. 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 circumferential surface of the other end contacts the inner periphery of a plurality of holes formed in boundary wall 340.

[0060] The storage chamber 310 of the hydrogen separation unit 300 is equipped 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 equipped with a collection pipe 360 ​​for extracting hydrogen gas.

[0061] The material and thickness of the housings 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-330g may be the same as those in the first embodiment. Similarly, the method of welding the hydrogen permeation sections 330a-330g to the boundary wall 340 may be the same as or follow that of the first embodiment.

[0062] 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., which will be described later, 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.

[0063] The manufacturing method of the hydrogen permeation section 330 of the third embodiment is not particularly limited. Fig. 15 shows an example of a manufacturing process for the hydrogen permeation section 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)) to complete the product (step (g)).

[0064] 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)).

[0065] In the third embodiment, a catalyst capable of dissociating hydrogen may be present on the surface of the hydrogen permeable section 330. The presence of such a catalyst facilitates dissociation of hydrogen molecules into hydrogen atoms when they come into contact with the surface of the hydrogen permeable section 330, thereby increasing hydrogen permeability. There are no particular limitations on such a catalyst as long as it exhibits the above-described effect, and an example of such a catalyst is palladium silver (Pd-25% Ag). Methods for providing a catalyst on the surface of the hydrogen permeable section 330 include sputtering, evaporation, and CVD (chemical vapor deposition), but from an industrial perspective, sputtering is preferred. The catalyst is preferably present on the surface of the hydrogen permeable section 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.

[0066] 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 defects 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.

[0067] FIG. 17 is a schematic diagram showing a state in which a catalyst is applied to the surface of a 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 cylindrical 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 a sufficient amount of 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 preferably present (applied) on the surface of the hydrogen permeation portion is also applicable to 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, the disk may be made of iron (Fe), stainless steel, or other materials. 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.

[0068] (Hydrogen separation device) Next, a hydrogen separation device 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 device functions. Below, the operation of this hydrogen separation device, 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).

[0069] First, in the initial 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).

[0070] 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 hydrogen permeation sections 330a-330g (and three other hydrogen permeation sections 330, not shown) that are cylindrical and have one closed end and the other open end, and are provided in the boundary wall 340, 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 other hydrogen permeation sections 330, not shown), which are metal membranes containing a Group 5 element, and moves to the collection chamber 320. The remaining mixed gas after hydrogen separation is then sent to the outside through the discharge pipe 351 (step S3). As described above, in the present invention, it is preferable to operate the hydrogen permeation sections 330a-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).

[0071] Meanwhile, the hydrogen extracted into the collection chamber 320 is sent to the outside through the collection pipe 360 ​​(step S4). Then, the separated hydrogen is collected in an external storage tank or the like (not shown).

[0072] 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.

[0073] [Variations] 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.

[0074] One such example is a modified hydrogen permeation section. In the above embodiments, an example was described in which the hydrogen permeable material was formed of a metal membrane, but the hydrogen permeation section 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 permeation section having such a form. For example, a dense, crystalline Pd / V layer with a total thickness of less than 7 mm formed on porous alumina is 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 An example is a porous membrane formed by depositing a Pd7 / Pd multilayer film. [Industrial Applicability]

[0075] 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 also be made smaller in size. [Explanation of symbols]

[0076] 100, 200, 300: Hydrogen separation unit 110, 210, 310: Containment rooms 120, 221, 222, 320: Collection Room 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 tubes 170, 271, 272: Rings 370: Joint 380: Welded parts 390: Catalyst

Claims

1. A hydrogen separation apparatus that separates and extracts hydrogen from a hydrogen-containing gas mixture, The hydrogen separation unit has a containment chamber to which the mixed gas is supplied, a collection chamber, a boundary section, and a plurality of hydrogen permeable sections. Multiple holes are provided in the aforementioned boundary portion. The plurality of hydrogen permeable sections can extract the hydrogen from the mixed gas, Each of the hydrogen permeable portions is formed in a cylindrical shape with one end closed and the other end open, and is joined to the boundary portion such that the outer surface of the other end is in contact with the inner circumference of the hole. The boundary portion and the plurality of hydrogen permeable portions separate the containment chamber and the collection chamber. A hydrogen separation apparatus in which the hydrogen contained in the mixed gas moves through the hydrogen permeator to the collection chamber.

2. The hydrogen separation apparatus according to claim 1, wherein the hydrogen permeate portion contains a group 5 element.

3. The hydrogen separation apparatus according to claim 1, wherein the hydrogen permeable portion has a form in which a metal containing a group 5 element is attached to a porous substrate.

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