Mixed gas separation device and mixed gas separation method

Abstract

To separate high-purity gas from a mixed gas with high efficiency and low cost. [Solution] The mixed gas separation device has a compression unit that compresses a mixed gas that is a mixture of multiple types of gases including hydrogen, a hydrogen absorption unit that has a hydrogen storage alloy that absorbs hydrogen and causes the hydrogen contained in the mixed gas compressed by the compression unit to be absorbed into the hydrogen storage alloy, an oxidation treatment unit that performs an oxidation treatment on the gas that has passed through the hydrogen absorption unit, and a gas storage unit that stores the gas after the oxidation treatment by the oxidation treatment unit.

Description

[Technical Field]

[0001] The present invention relates to a mixed gas separation apparatus and a mixed gas separation method. [Background technology]

[0002] In recent years, natural hydrogen, which exists in nature, has been attracting attention as a source of hydrogen, a clean energy resource. Natural hydrogen exists underground, on the seabed, and has been observed in various parts of the world. However, such natural hydrogen often exists in the form of a mixture with other gases, such as helium and methane, making it difficult to utilize.

[0003] For example, a mixture of hydrogen and helium can be used as a fuel without separating the hydrogen and helium if there is sufficient hydrogen, or it can be used as a helium source if there is sufficient helium, with the hydrogen removed by an oxidation reaction.

[0004] Furthermore, it is also possible to separate hydrogen and helium from the mixed gas to obtain high-purity gases of each. Generally, methods for separating various high-purity gases from a mixed gas containing multiple types of gases include cryogenic separation, molecular sieve separation, and membrane separation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. Hei 2-204302 Summary of the Invention [Problem to be solved by the invention]

[0006] However, separating high-purity gases from a mixture of hydrogen and other gases involves problems such as low separation efficiency and increased costs. For example, in the case of a mixture of hydrogen and helium, it is difficult to separate hydrogen and helium using molecular sieves or membrane separation because both hydrogen and helium have very small molecular diameters. Even if hydrogen and helium could be separated using molecular sieves or membrane separation, multiple separation stages would be required, increasing costs. Furthermore, because hydrogen and helium both have very low liquefaction temperatures (helium: -269°C, hydrogen: -253°C) and the freezing point of hydrogen is -259°C, these temperatures are too close for phase separation, making it difficult to separate hydrogen and helium using cryogenic separation involving rectification.

[0007] While separating hydrogen and helium is difficult, hydrogen can be used as an energy carrier, and helium is a rare gas that is used in gaseous form for leak testing, lasers, etc. Therefore, it is desirable to recover both hydrogen and helium from a mixed gas.

[0008] The present disclosure has been made in consideration of the above points, and aims to provide a mixed gas separation device and a mixed gas separation method that can separate high-purity gas from a mixed gas with high efficiency and low cost. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, a mixed gas separation device includes a compression unit that compresses a mixed gas containing multiple types of gases including hydrogen, a hydrogen absorption unit that includes a hydrogen storage alloy that absorbs hydrogen and causes the hydrogen contained in the mixed gas compressed by the compression unit to be absorbed into the hydrogen storage alloy, an oxidation treatment unit that performs an oxidation treatment on the gas that has passed through the hydrogen absorption unit, and a gas storage unit that stores the gas after the oxidation treatment by the oxidation treatment unit. [Effects of the Invention]

[0010] According to the present disclosure, high-purity gas can be separated from a mixed gas with high efficiency and low cost. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing the configuration of a mixed gas separation apparatus according to one embodiment. [Figure 2] FIG. 2 is a diagram illustrating the structure of the hydrogen storage portion. [Figure 3] FIG. 3 is a flow diagram showing a mixed gas separation method according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention will be described below with reference to the accompanying drawings. The embodiment described below is an example and should not be construed as being limited by this description.

[0013] Fig. 1 is a diagram showing the configuration of a mixed gas separation apparatus 100 according to one embodiment. This mixed gas separation apparatus 100 separates hydrogen and helium from a mixed gas of hydrogen and helium, but the mixed gas targeted in this disclosure is not limited to a mixed gas of hydrogen and helium. That is, for example, when separating hydrogen and methane from a mixed gas of hydrogen and methane, a mixed gas separation apparatus having a configuration similar to that of the mixed gas separation apparatus 100 shown in Fig. 1 can be used.

[0014] The mixed gas separation apparatus 100 shown in FIG. 1 includes a compression section 110, hydrogen absorption sections 120-1 to 120-N (N is an integer of 1 or more), heating sections 130-1 to 130-N, a hydrogen storage section 140, an oxidation treatment section 150, a drying treatment section 160, and a helium storage section 170.

[0015] The compression section 110 includes a compressor that compresses the mixed gas taken into the mixed gas separation device 100, and sends the compressed high-pressure mixed gas to the hydrogen absorption section 120-1.

[0016] Each of the hydrogen absorbing units 120-1 to 120-N has a hydrogen storage alloy and absorbs hydrogen contained in the mixed gas. That is, each of the hydrogen absorbing units 120-1 to 120-N passes the mixed gas around the hydrogen storage alloy, causing the hydrogen contained in the mixed gas to be absorbed in the hydrogen storage alloy. The hydrogen absorbing units 120-1 to 120-(N-1) then send the mixed gas that has passed around the hydrogen storage alloy to the next hydrogen absorbing unit 120-2 to 120-N. The hydrogen absorbing unit 120-N also sends the off-gas that has passed around the hydrogen storage alloy to the oxidation treatment unit 150. The number N of stages of the hydrogen absorbing units 120-1 to 120-N is determined appropriately depending on the hydrogen concentration in the mixed gas taken into the mixed gas separation apparatus 100 and the desired purity of hydrogen or helium obtained by separation.

[0017] Furthermore, after hydrogen absorbing units 120-1 to 120-N absorb hydrogen in the hydrogen storage alloy, when they are heated by corresponding heating units 130-1 to 130-N, they send the hydrogen released from the hydrogen storage alloy to hydrogen storage unit 140. That is, when a hydrogen storage alloy is heated, it releases the absorbed hydrogen molecules, so that hydrogen absorbing units 120-1 to 120-N send the hydrogen released from the hydrogen storage alloy to hydrogen storage unit 140.

[0018] Each of the hydrogen absorbing units 120-1 to 120-N includes a hydrogen absorbing alloy 121 configured by arranging metal atoms 122 in a lattice pattern, as shown in Fig. 2(a), for example. When this hydrogen absorbing alloy 121 comes into contact with a high-pressure mixed gas, hydrogen molecules 201 contained in the mixed gas combine with the metal atoms 122 to form a metal hydride, as shown in Fig. 2(b), for example. When the hydrogen absorbing alloy 121 that has become a metal hydride as shown in Fig. 2(b) is heated, it releases the absorbed hydrogen molecules 201.

[0019] The heating units 130-1 to 130-N heat the corresponding hydrogen storage units 120-1 to 120-N, respectively. Specifically, after the mixed gas passes through the hydrogen storage units 120-1 to 120-N and the off-gas is sent to the oxidation treatment unit 150, and the mixed gas and the off-gas are scavenged, the heating units 130-1 to 130-N heat the hydrogen storage units 120-1 to 120-N, respectively, to release hydrogen from the hydrogen storage alloy. The heating temperature at which the hydrogen storage alloy releases the hydrogen it has absorbed varies depending on the type of metal atoms that make up the hydrogen storage alloy, but considering that flammable hydrogen is released, it is preferable to use a hydrogen storage alloy that releases hydrogen at a heating temperature of, for example, less than 100°C. Therefore, the heating units 130-1 to 130-N heat the hydrogen absorbing units 120-1 to 120-N, respectively, to a heating temperature of, for example, 150° C. or less at which the hydrogen absorbing alloy releases hydrogen.

[0020] The hydrogen storage unit 140 stores the hydrogen delivered from the hydrogen absorbing units 120-1 to 120-N. That is, the hydrogen storage unit 140 stores the hydrogen released when the hydrogen absorbing alloy is heated. The hydrogen stored in the hydrogen storage unit 140 is high-purity hydrogen separated from the helium in the mixed gas. The hydrogen stored in the hydrogen storage unit 140 can be used as hydrogen energy as is, or can be further refined to produce even higher-purity hydrogen for use.

[0021] The oxidation treatment unit 150 is equipped with an oxidation catalyst, and when off-gas after hydrogen absorption is discharged from the hydrogen absorption unit 120-N, it takes in oxygen gas and performs oxidation treatment on the off-gas. Specifically, since helium-rich off-gas is discharged from the hydrogen absorption unit 120-N, the oxidation treatment unit 150 oxidizes the hydrogen remaining in the off-gas and converts it into moisture, thereby removing the hydrogen remaining in the off-gas. As a result, the off-gas becomes high-purity helium gas.

[0022] The drying treatment unit 160 is provided with a desiccant and absorbs moisture from the off-gas oxidized by the oxidation treatment unit 150, removing moisture generated by the oxidation of hydrogen. That is, since the off-gas contains moisture due to the oxidation treatment by the oxidation treatment unit 150, the drying treatment unit 160 removes moisture as an impurity from the off-gas that has become helium gas.

[0023] Helium storage unit 170 stores the helium gas that has been dried by drying unit 160. That is, helium storage unit 170 stores high-purity helium gas that has been separated from hydrogen. The helium gas stored in helium storage unit 170 can be used as is in a gaseous state for leak tests or lasers, or it can be cooled to a temperature close to absolute zero and liquefied for use in ultra-low temperature regions.

[0024] Next, a mixed gas separation method using the mixed gas separation apparatus 100 configured as described above will be described with reference to the flow chart shown in FIG.

[0025] When the mixed gas is taken into the mixed gas separation apparatus 100, the mixed gas is compressed by the compression unit 110 (step S101). The mixed gas is, for example, a mixed gas of hydrogen and helium, and may be natural hydrogen, also known as white hydrogen or gold hydrogen, mined from the earth or the seabed. The mixed gas may also be exhaust gas generated from a factory, laboratory, or the like.

[0026] The compressed and high-pressure mixed gas flows sequentially into the hydrogen absorbing units 120-1 to 120-N, and passes around the hydrogen storage alloys of the hydrogen absorbing units 120-1 to 120-N, where the hydrogen in the mixed gas is absorbed by the hydrogen storage alloy (step S102). As a result, the mixed gas that has passed through the hydrogen absorbing units 120-1 to 120-N becomes helium-rich off-gas. When the hydrogen absorbing units 120-1 to 120-N are provided in multiple stages (i.e., when N is 2 or more), the amount of hydrogen remaining in the mixed gas decreases as it progresses toward the later hydrogen absorbing units 120-1 to 120-N, and helium-rich off-gas is obtained.

[0027] Then, when the helium-rich off-gas is sent from the final-stage hydrogen occlusion unit 120-N to the oxidation treatment unit 150, the off-gas is oxidized by the oxidation treatment unit 150 (step S103). That is, the hydrogen remaining in the helium-rich off-gas is oxidized by the oxidation action of the oxidation catalyst, generating moisture, and high-purity helium gas containing moisture is produced.

[0028] The moisture-containing off-gas is sent to the drying treatment unit 160, where it is dried (step S104). That is, the moisture contained in the off-gas is removed by a drying treatment using a desiccant, and high-purity helium gas is generated. The generated high-purity helium gas is stored in the helium storage unit 170 (step S105). This makes it possible to recover high-purity helium from the mixed gas.

[0029] Then, the mixed gas and off-gas remaining inside the mixed gas separation apparatus 100 are scavenged (step S106), and the heating units 130-1 to 130-N heat the hydrogen storage alloys of the corresponding hydrogen storage units 120-1 to 120-N (step S107). As a result, the hydrogen stored in the hydrogen storage alloys is released, and the released hydrogen is stored in the hydrogen storage unit 140 (step S108). The hydrogen released from the hydrogen storage alloy is high-purity hydrogen separated from helium, and therefore high-purity hydrogen can be recovered from the mixed gas.

[0030] Here, after the mixed gas passes through all of the hydrogen absorbing units 120-1 to 120-N, scavenging of the mixed gas and off-gas is performed, and the hydrogen absorbing units 120-1 to 120-N are simultaneously heated by the heating units 130-1 to 130-N, but the timing of scavenging and heating is not limited to this. That is, for example, as the mixed gas passes through each of the hydrogen absorbing units 120-1 to 120-N, the hydrogen absorbing units 120-1 to 120-N through which the mixed gas has passed may be sequentially scavenged, and the hydrogen storage alloy may be sequentially heated in the hydrogen absorbing units 120-1 to 120-N for which scavenging has been completed.

[0031] As described above, according to this embodiment, hydrogen in a mixed gas is absorbed by a hydrogen storage alloy, and the helium-rich off-gas resulting from the hydrogen absorption is subjected to oxidation and drying processes to remove the remaining hydrogen, and the resulting high-purity helium is stored. The hydrogen storage alloy is then heated to release the absorbed hydrogen, and the resulting high-purity hydrogen is stored. Therefore, hydrogen and helium can be separated from a hydrogen and helium mixed gas using simple equipment, and high-purity gas can be separated from the mixed gas with high efficiency and low cost.

[0032] In the above embodiment, the mixed gas taken into the mixed gas separation device 100 is compressed by the compression section 110, but as a pre-processing step before compression, a process may be performed to remove impurities dissolved in the mixed gas, for example, using a filter.

[0033] The hydrogen storage unit 140 and the helium storage unit 170 may store hydrogen and helium in a gaseous state or in a liquid state, respectively. Furthermore, before being stored in the hydrogen storage unit 140 and the helium storage unit 170, the hydrogen and helium may be purified by various methods and then stored.

[0034] The following is further disclosed regarding the above embodiment. [1] A compression unit that compresses a mixed gas containing multiple types of gases including hydrogen; a hydrogen absorbing unit including a hydrogen absorbing alloy for absorbing hydrogen, the hydrogen being contained in the mixed gas compressed by the compression unit being absorbed into the hydrogen absorbing alloy; an oxidation treatment unit that performs oxidation treatment on the gas that has passed through the hydrogen absorbing unit; a gas storage unit that stores the gas after oxidation treatment by the oxidation treatment unit; A mixed gas separation device having:

[0035] [2] a heating unit that heats the hydrogen storage alloy included in the hydrogen storage unit; a hydrogen storage unit that stores hydrogen released from a hydrogen storage alloy heated by the heating unit; The mixed gas separation apparatus according to [1] above, further comprising:

[0036] [3] The heating unit is After the gas is stored in the gas storage unit and the inside of the mixed gas separation device is purged, the hydrogen storage alloy is heated. The mixed gas separation device according to [2] above.

[0037] [4] The heating unit is After the gas passes through the hydrogen absorbing portion and is scavenged, the hydrogen absorbing alloy included in the hydrogen absorbing portion is heated. The mixed gas separation device according to [2] above.

[0038] [5] The hydrogen storage portion is A plurality of hydrogen storage alloys are provided in multiple stages, and the mixed gas is passed around the plurality of hydrogen storage alloys in sequence. The mixed gas separation apparatus according to any one of the above [1] to [3].

[0039] [6] A drying treatment unit that removes moisture generated by the oxidation of hydrogen by the oxidation treatment unit. The mixed gas separation apparatus according to any one of the above [1] to [3], further comprising:

[0040] [7] The compression section Compresses a gas mixture of hydrogen and helium The mixed gas separation apparatus according to any one of the above [1] to [3].

[0041] [8] Compressing a mixed gas containing multiple types of gases including hydrogen; a hydrogen storage alloy that stores hydrogen by passing a compressed mixed gas around the mixed gas; and performing an oxidation treatment on the gas that has passed around the hydrogen storage alloy; storing the gas after the oxidation treatment; A method for separating a mixed gas comprising: [Explanation of symbols]

[0042] 110 Compression section 120-1~120-N Hydrogen storage section 130-1~130-N Heating section 140 Hydrogen storage unit 150 Oxidation treatment section 160 Drying processing section 170 Helium storage

Claims

1. a compression unit that compresses a mixed gas containing a plurality of types of gases including hydrogen; a hydrogen absorbing unit including a hydrogen absorbing alloy for absorbing hydrogen, the hydrogen being contained in the mixed gas compressed by the compression unit being absorbed into the hydrogen absorbing alloy; an oxidation treatment unit that performs oxidation treatment on the gas that has passed through the hydrogen absorbing unit; a gas storage unit that stores the gas after oxidation treatment by the oxidation treatment unit; a drying treatment unit that removes moisture generated by the oxidation of hydrogen by the oxidation treatment unit; A mixed gas separation device having:

2. a heating unit that heats the hydrogen storage alloy included in the hydrogen storage unit; a hydrogen storage unit that stores hydrogen released from a hydrogen storage alloy heated by the heating unit; 10. The mixed gas separation apparatus of claim 1, further comprising:

3. The heating unit is After the gas is stored in the gas storage unit and the inside of the mixed gas separation device is purged, the hydrogen storage alloy is heated. The mixed gas separation apparatus according to claim 2.

4. The heating unit is After the gas passes through the hydrogen absorbing portion and is scavenged, the hydrogen absorbing alloy included in the hydrogen absorbing portion is heated. The mixed gas separation apparatus according to claim 2.

5. The hydrogen absorbing portion is 2. The mixed gas separation device according to claim 1, further comprising a plurality of hydrogen storage alloys arranged in multiple stages, and the mixed gas is passed around the plurality of hydrogen storage alloys in sequence.

6. The compression section Compresses a gas mixture of hydrogen and helium The mixed gas separation apparatus according to claim 1 .

7. Compressing a mixed gas containing a plurality of types of gases including hydrogen; a hydrogen storage alloy that stores hydrogen by passing a compressed mixed gas around the mixed gas; and performing an oxidation treatment on the gas that has passed around the hydrogen storage alloy; storing the gas after the oxidation treatment; performing a drying process to remove moisture generated by the oxidation process from the gas after the oxidation process; A method for separating a mixed gas comprising:

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