Hydrogen supply system

Abstract

To provide a hydrogen supply system in which the purification load for the hydrogen purification unit can be reduced.SOLUTION: A hydrogen supply system 100 includes, in the flow of a raw material, a deaeration unit 20 for removing the inorganic gas contained in the raw material on the upstream side of a dehydrogenation reaction unit 3. In this case, the dehydrogenation reaction unit 3 can dehydrogenate the raw material in a state where the inorganic gas is removed by the deaeration unit 20. Thereby, the purification load of a hydrogen purification unit 8 due to the inclusion of the inorganic gas component in the hydrogen-containing gas can be reduced.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hydrogen supply system that supplies hydrogen. [Background technology]

[0002] Known conventional hydrogen supply systems include, for example, the one disclosed in Patent Document 1. The hydrogen supply system of Patent Document 1 includes a tank for storing a hydride of an aromatic hydrocarbon as a raw material, a dehydrogenation reaction section for obtaining hydrogen by dehydrogenating the raw material supplied from the tank, a gas-liquid separation section for separating the hydrogen obtained in the dehydrogenation reaction section into gas and liquid, and a hydrogen purification section for purifying the hydrogen obtained by gas-liquid separation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-232607 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the hydrogen supply system as described above, the raw material may contain inorganic gases such as oxygen and nitrogen. Such inorganic gas components are also contained in the hydrogen-containing gas after dehydrogenation. Therefore, the hydrogen purification unit needs to remove the inorganic gases from the hydrogen-containing gas. Furthermore, among the inorganic gases, oxygen generates water during the dehydrogenation reaction, thereby increasing the dew point of the hydrogen-containing gas. In this case, the purification load on the hydrogen purification unit becomes high. As a result, there is a problem that the purification load on the hydrogen purification unit becomes high.

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a hydrogen supply system that can reduce the purification load on the hydrogen purification section. [Means for solving the problem]

[0006] In order to solve the above problems, the hydrogen supply system of the present invention is a hydrogen supply system that supplies hydrogen, and includes a dehydrogenation reaction section that obtains a hydrogen-containing gas by dehydrogenating a raw material containing a hydride, a hydrogen purification section that removes dehydrogenation products from the hydrogen-containing gas obtained in the dehydrogenation reaction section to obtain a purified gas containing high-purity hydrogen, and a degassing section that removes inorganic gases contained in the raw material upstream of the dehydrogenation reaction section in the flow of the raw material.

[0007] In the hydrogen supply system, the dehydrogenation reaction section obtains a hydrogen-containing gas by dehydrogenating the raw material. The hydrogen purification section removes dehydrogenation products from the hydrogen-containing gas obtained in the dehydrogenation reaction section to obtain a purified gas containing high-purity hydrogen. Therefore, the purification load of the hydrogen purification section may be affected by components contained in the hydrogen-containing gas from the dehydrogenation reaction section. In response to this, the hydrogen supply system includes a degassing section that removes inorganic gas contained in the raw material upstream of the dehydrogenation reaction section in the flow of the raw material. In this case, the dehydrogenation reaction section can dehydrogenate the raw material from which the inorganic gas has been removed by the degassing section. This can reduce the purification load of the hydrogen purification section due to the presence of inorganic gas components in the hydrogen-containing gas. As a result, the purification load of the hydrogen purification section can be reduced.

[0008] In this hydrogen supply system, the degassing section may be constituted by a degassing membrane separator, which allows the degassing section to efficiently remove inorganic gases from the raw material. Effect of the Invention

[0009] According to the present invention, it is possible to provide a hydrogen supply system capable of reducing the purification load on the hydrogen purification section. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration of a hydrogen supply system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the hydrogen supply system according to the present invention will now be described in detail with reference to the drawings. In the following description, the same or corresponding parts are designated by the same reference numerals, and duplicated description will be omitted.

[0012] FIG. 1 is a block diagram showing the configuration of a hydrogen supply system according to an embodiment of the present invention. The hydrogen supply system 100 uses an organic compound (liquid at room temperature) as a raw material. In the process of hydrogen purification, the raw organic compound (liquid at room temperature) is dehydrogenated and a dehydrogenation product (organic compound (liquid at room temperature)) is removed. An example of the organic compound as the raw material is organic hydride. A suitable example of the organic hydride is a hydride obtained by reacting hydrogen, which is produced in large quantities in oil refineries, with aromatic hydrocarbons. In addition, the organic hydride is not limited to aromatic hydrogenated compounds, and there is also a system of 2-propanol (which produces hydrogen and acetone). The organic hydride can be transported to the hydrogen supply system 100 as a liquid fuel by a tanker truck or the like, similar to gasoline. In this embodiment, methylcyclohexane (hereinafter referred to as MCH) is used as the organic hydride. In addition, aromatic hydrocarbon hydrides such as cyclohexane, dimethylcyclohexane, ethylcyclohexane, decalin, methyldecalin, dimethyldecalin, and ethyldecalin can be used as organic hydrides (aromatic compounds are particularly suitable examples with high hydrogen content). The hydrogen supply system 100 can supply hydrogen to fuel cell vehicles (FCVs) and hydrogen engine vehicles. It is also applicable to the production of hydrogen from liquid hydrocarbon raw materials such as natural gas containing methane as the main component, LPG containing propane as the main component, or gasoline, naphtha, kerosene, and diesel.

[0013] As shown in FIG. 1, the hydrogen supply system 100 according to the present embodiment includes a liquid transfer pump 1, a heat exchanger 2, a dehydrogenation reaction unit 3, a heater 4, a gas-liquid separator 6, a compressor 7, and a hydrogen purifier 8. Among these, the liquid transfer pump 1, the heat exchanger 2, and the dehydrogenation reaction unit 3 belong to a hydrogen production unit 10 that produces a hydrogen-containing gas. The gas-liquid separator 6, the compressor 7, and the hydrogen purifier 8 belong to a hydrogen purity adjuster 11 that increases the purity of hydrogen. The hydrogen supply system 100 also includes lines L1 to L12. In this embodiment, MCH is used as a raw material, and the dehydrogenation product removed in the hydrogen purification process is toluene. In reality, not only toluene but also unreacted MCH and small amounts of by-products and impurities are present, but in this embodiment, they are mixed with toluene and behave the same as toluene. Therefore, in the following description, what is referred to as "toluene" includes unreacted MCH and by-products.

[0014] Lines L1 to L12 are flow paths through which MCH, toluene, hydrogen-containing gas, off-gas, high-purity hydrogen, or a heating medium passes. Line L1 is a line for liquid transfer pump 1 to pump MCH from an MCH tank (not shown), and connects liquid transfer pump 1 to the MCH tank. Line L2 connects liquid transfer pump 1 to dehydrogenation reaction section 3. Line L3 connects dehydrogenation reaction section 3 to gas-liquid separation section 6. Line L4 connects gas-liquid separation section 6 to a toluene tank (not shown). Line L5 connects gas-liquid separation section 6 to compression section 7. Line L6 connects compression section 7 to hydrogen purification section 8. Line L7 connects hydrogen purification section 8 to a supply destination of off-gas. Line L8 connects hydrogen purification section 8 to a supply device for purified gas (not shown). Lines L11 and L12 connect heating section 4 to dehydrogenation reaction section 3. The lines L11 and L12 allow the heat transfer medium to flow.

[0015] The liquid transfer pump 1 supplies the raw material MCH to the dehydrogenation reaction section 3. The MCH transported from outside by a tank truck or the like is stored in an MCH tank. The MCH stored in the MCH tank is supplied to the dehydrogenation reaction section 3 by the liquid transfer pump 1 via lines L1 and L2.

[0016] The heat exchanger 2 exchanges heat between the MCH flowing through the line L2 and the hydrogen-containing gas flowing through the line L3. The hydrogen-containing gas coming out of the dehydrogenation reaction section 3 has a higher temperature than the MCH. Therefore, in the heat exchanger 2, the MCH is heated by the heat of the hydrogen-containing gas. As a result, the MCH is supplied to the dehydrogenation reaction section 3 in a state where its temperature has increased. The MCH is supplied to the dehydrogenation reaction section 3 together with the off-gas supplied from the hydrogen purification section 8 via the line L7.

[0017] The dehydrogenation reaction section 3 is a device that obtains hydrogen by dehydrogenating MCH. That is, the dehydrogenation reaction section 3 is a device that extracts hydrogen from MCH by a dehydrogenation reaction using a dehydrogenation catalyst. The dehydrogenation catalyst is not particularly limited, but is selected from, for example, a platinum catalyst, a palladium catalyst, and a nickel catalyst. These catalysts may be supported on a carrier such as alumina, silica, and titania. The reaction of organic hydrides is a reversible reaction, and the direction of the reaction changes depending on the reaction conditions (temperature, pressure) (subject to the constraints of chemical equilibrium). On the other hand, the dehydrogenation reaction is an endothermic reaction that always increases the number of molecules. Therefore, high temperature and low pressure conditions are advantageous. Since the dehydrogenation reaction is an endothermic reaction, heat is supplied to the dehydrogenation reaction section 3 from the heating section 4 via a heat medium circulating through lines L11 and L12. The dehydrogenation reaction section 3 has a mechanism that allows heat exchange between the MCH flowing through the dehydrogenation catalyst and the heat medium from the heating section 4. The hydrogen-containing gas extracted in the dehydrogenation reaction section 3 is supplied to the gas-liquid separation section 6 via a line L3. The hydrogen-containing gas in the line L3 is supplied to the gas-liquid separation section 6 in a state where it contains toluene, which is a liquid, as a mixture.

[0018] The heating section 4 heats the heat medium and supplies the heat medium to the dehydrogenation reaction section 3 via a line L11. The heated heat medium is returned to the heating section 4 via a line L12. The heat medium is not particularly limited, and oil or the like may be used. The heating section 4 may be any type that can heat the dehydrogenation reaction section 3. For example, the heating section 4 may directly heat the dehydrogenation reaction section 3, or may heat the MCH supplied to the dehydrogenation reaction section 3 by heating the line L2. The heating section 4 may heat both the dehydrogenation reaction section 3 and the MCH supplied to the dehydrogenation reaction section 3. For example, a burner or an engine may be used as the heating section 4.

[0019] The gas-liquid separation unit 6 is a tank that separates toluene from the hydrogen-containing gas. The gas-liquid separation unit 6 separates hydrogen, which is a gas, from toluene, which is a liquid, by storing the hydrogen-containing gas containing toluene as a mixture. The hydrogen-containing gas supplied to the gas-liquid separation unit 6 is cooled by the heat exchange unit 2. The gas-liquid separation unit 6 may be cooled by a cooling medium from a cold heat source. In this case, the gas-liquid separation unit 6 has a mechanism capable of exchanging heat between the hydrogen-containing gas in the gas-liquid separation unit 6 and the cooling medium from the cold heat source. The toluene separated by the gas-liquid separation unit 6 is supplied to a toluene tank (not shown) via a line L4. The hydrogen-containing gas separated by the gas-liquid separation unit 6 is supplied to the hydrogen purification unit 8 via lines L5 and L6 by the pressure of the compression unit 7. When the hydrogen-containing gas is cooled, a part of the gas (toluene) is liquefied, and the gas-liquid separation unit 6 can separate the toluene from the non-liquefied gas (hydrogen). The lower the gas temperature, the more efficient the separation becomes, and increasing the pressure further promotes the liquefaction of toluene.

[0020] The hydrogen purification unit 8 removes the dehydrogenation product (toluene in this embodiment) from the hydrogen-containing gas obtained in the dehydrogenation reaction unit 3 and separated into gas and liquid in the gas-liquid separation unit 6. In this way, the hydrogen purification unit 8 purifies the hydrogen-containing gas to obtain high-purity hydrogen (purified gas). The obtained purified gas is supplied to line L8. The off-gas generated in the hydrogen purification unit 8 is supplied to the dehydrogenation reaction unit 3 via line L7.

[0021] The hydrogen purification unit 8 varies depending on the hydrogen purification method employed, but specifically, when membrane separation is used as the hydrogen purification method, it is a hydrogen separation device equipped with a hydrogen separation membrane, and when the PSA (pressure swing adsorption) method or the TSA (temperature swing adsorption) method is used, it is an adsorption removal device equipped with multiple adsorption towers that store adsorbents that adsorb impurities.

[0022] A case where the hydrogen purification unit 8 uses membrane separation will be described. In this method, a hydrogen-containing gas pressurized to a predetermined pressure by a compression unit (not shown) is made to pass through a membrane heated to a predetermined temperature, thereby removing dehydrogenation products and obtaining high-purity hydrogen gas (purified gas). The pressure of the permeated gas that has permeated the membrane is reduced compared to the pressure before permeating the membrane. On the other hand, the pressure of the non-permeated gas that has not permeated the membrane is approximately the same as the predetermined pressure before permeating the membrane. At this time, the non-permeated gas that has not permeated the membrane corresponds to the off-gas of the hydrogen purification unit 8.

[0023] There are no particular limitations on the type of membrane used in hydrogen purification unit 8, and it is possible to use porous membranes (those that separate by molecular flow, those that separate by surface diffusion flow, those that separate by capillary condensation, those that separate by molecular sieving, etc.) or non-porous membranes. As the membrane used in hydrogen purification unit 8, for example, metal membranes (PbAg-based, PdCu-based, Nb-based, etc.), zeolite membranes, inorganic membranes (silica membranes, carbon membranes, etc.), and polymer membranes (polyimide membranes, etc.) can be used.

[0024] A case where the PSA method is adopted as a removal method of the hydrogen purification unit 8 will be described. The adsorbent used in the PSA method has the property of adsorbing toluene contained in the hydrogen-containing gas under high pressure and desorbing the adsorbed toluene under low pressure. The PSA method utilizes such a property of the adsorbent. That is, by increasing the pressure inside the adsorption tower, the toluene contained in the hydrogen-containing gas is adsorbed by the adsorbent and removed, thereby obtaining high-purity hydrogen gas (purified gas). When the adsorption function of the adsorbent in the adsorption tower is reduced by adsorption, the pressure inside the adsorption tower is reduced to desorb the toluene adsorbed on the adsorbent, and at the same time, a part of the removed purified gas is reversed to remove the desorbed toluene from the adsorption tower, thereby regenerating the adsorption function of the adsorbent (at this time, the hydrogen-containing gas containing at least hydrogen and toluene discharged by removing toluene from the adsorption tower corresponds to the off-gas from the hydrogen purification unit 8).

[0025] A case where the TSA method is adopted as the removal method of the hydrogen purification unit 8 will be described. The adsorbent used in the TSA method has the property of adsorbing toluene contained in the hydrogen-containing gas at room temperature and desorbing the adsorbed toluene at high temperature. The TSA method utilizes such a property of the adsorbent. That is, by bringing the temperature inside the adsorption tower to room temperature, the toluene contained in the hydrogen-containing gas is adsorbed by the adsorbent and removed, thereby obtaining high-purity hydrogen gas (high-purity hydrogen). When the adsorption function of the adsorbent in the adsorption tower is reduced by adsorption, the toluene adsorbed by the adsorbent is desorbed by raising the temperature inside the adsorption tower, and the desorbed toluene is removed from the adsorption tower by backflowing a part of the removed high-purity hydrogen, thereby regenerating the adsorption function of the adsorbent (at this time, the hydrogen-containing gas containing at least hydrogen and toluene discharged by removing toluene from the adsorption tower corresponds to the off-gas from the hydrogen purification unit 8).

[0026] Next, characteristic features of the above-mentioned hydrogen supply system 100 will be described.

[0027] The raw material used in the hydrogen supply system 100 may contain inorganic gases dissolved therein. The inorganic gases are gases such as oxygen and nitrogen. In response to this, the hydrogen supply system 100 is equipped with a degassing section 20. The degassing section 20 removes inorganic gases contained in the raw material upstream of the dehydrogenation reaction section 3 in the flow of the raw material.

[0028] Specifically, the degassing section 20 is provided on the line L2 that connects the liquid transfer pump 1 and the dehydrogenation reaction section 3. As a result, the raw material from the liquid transfer pump 1 is supplied to the degassing section 20 via the line L2a. Inorganic gas components dissolved in the raw material are removed in the degassing section 20. Then, the raw material from which the inorganic gas components have been removed is supplied to the dehydrogenation reaction section 3 via the line L2b. The degassing section 20 is provided downstream of the heat exchange section 2. Therefore, the heat exchange section 2 is provided in the line L2b.

[0029] The degassing section 20 is composed of a device capable of removing inorganic gas from the raw material. Specifically, the degassing section 20 may be composed of a degassing membrane separator. The degassing membrane separator is a device that degasses the raw material by using a degassing membrane. The degassing membrane separator separates the raw material from the inorganic gas by passing the raw material through a degassing membrane. The degassing section 20 discharges the removed inorganic gas from the degassing section 20 to the outside. Then, the degassing section 20 supplies the raw material from which the inorganic gas has been removed to the dehydrogenation reaction section 3.

[0030] The device constituting the degassing section 20 is not limited to a degassing membrane separator. For example, the degassing section 20 may be a device using dissolved gas separation by a liquid cyclone method, ultrasonic gas separation, or the like.

[0031] Next, the operation and effect of the hydrogen supply system 100 according to this embodiment will be described.

[0032] First, as a comparative example, a hydrogen supply system not having the above-mentioned degassing unit 20 will be described. In such a hydrogen supply system, the raw material may contain inorganic gases such as oxygen and nitrogen. Such inorganic gas components are also contained in the hydrogen-containing gas after dehydrogenation. Therefore, the hydrogen purification unit 8 needs to remove the inorganic gases from the hydrogen-containing gas. In addition, oxygen among the inorganic gases generates water during the dehydrogenation reaction, and therefore increases the dew point of the hydrogen-containing gas. In this case, the purification load on the hydrogen purification unit 8 becomes high. As a result of the above, there is a problem that the purification load on the hydrogen purification unit 8 becomes high.

[0033] In contrast, the hydrogen supply system 100 of this embodiment is a hydrogen supply system 100 that supplies hydrogen, and includes a dehydrogenation reaction section 3 that obtains a hydrogen-containing gas by dehydrogenating a raw material containing a hydride, a hydrogen purification section 8 that removes dehydrogenation products from the hydrogen-containing gas obtained in the dehydrogenation reaction section 3 to obtain a purified gas containing high-purity hydrogen, and a degassing section 20 that removes inorganic gases contained in the raw material upstream of the dehydrogenation reaction section 3 in the flow of the raw material.

[0034] In the hydrogen supply system 100, the dehydrogenation reaction section 3 obtains a hydrogen-containing gas by dehydrogenating the raw material. The hydrogen purification section 8 removes the dehydrogenation product from the hydrogen-containing gas obtained in the dehydrogenation reaction section 3 to obtain a purified gas containing high-purity hydrogen. Therefore, the purification load of the hydrogen purification section 8 may be affected by the components contained in the hydrogen-containing gas from the dehydrogenation reaction section 3. In response to this, the hydrogen supply system 100 includes a degassing section 20 that removes inorganic gas contained in the raw material upstream of the dehydrogenation reaction section 3 in the flow of the raw material. In this case, the dehydrogenation reaction section 3 can dehydrogenate the raw material from which the inorganic gas has been removed by the degassing section 20. This can reduce the purification load of the hydrogen purification section 8 due to the presence of inorganic gas components in the hydrogen-containing gas. As a result, the purification load of the hydrogen purification section 8 can be reduced.

[0035] In this hydrogen supply system 100, the degassing section 20 may be configured by a degassing membrane separator. This allows the degassing section 20 to efficiently remove inorganic gases from the raw material.

[0036] The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, a hydrogen station for an FVC is exemplified as a hydrogen supply system, but the hydrogen supply system may be a hydrogen supply system for a distributed power source such as a household power source or an emergency power source. [Explanation of symbols]

[0037] 3...dehydrogenation reaction section, 8...hydrogen purification section, 20...degassing section, 100...hydrogen supply system.

Claims

1. A hydrogen supply system for a distributed power source, comprising: a dehydrogenation reaction section that generates a hydrogen-containing gas by dehydrogenating a raw material containing a hydride; a gas-liquid separation section for removing a dehydrogenation product from the hydrogen-containing gas produced in the dehydrogenation reaction section; a degassing section that removes inorganic gases contained in the raw material, the degassing section being located upstream of the dehydrogenation section in the flow of the raw material; a hydrogen purification unit that produces a purified gas containing high-purity hydrogen from the hydrogen-containing gas from which the dehydrogenation product has been removed in the gas-liquid separation unit.

2. 2. The hydrogen supply system according to claim 1, wherein the degassing unit is configured by at least one of a degassing membrane separator, a liquid cyclone type dissolved gas separator, and an ultrasonic gas separator.

3. A hydrogen supply system as described in claim 1 or 2, wherein the hydrogen purification section is at least one of PSA and TSA.

4. A hydrogen supply system described in any one of claims 1 to 3, wherein the inorganic gas contained in the raw material includes oxygen and nitrogen.

5. A hydrogen supply system as described in any one of claims 1 to 4, comprising a pump that supplies the raw material to the dehydrogenation reaction section, and the degassing section is provided between the pump and the dehydrogenation reaction section.

6. A hydrogen supply system as described in any one of claims 1 to 5, comprising a heat exchange section that performs heat exchange between the hydrogen-containing gas produced in the dehydrogenation reaction section and the raw material, the heat exchange section being provided between the degassing section and the dehydrogenation reaction section.

7. A hydrogen supply system as described in any one of claims 1 to 6, comprising a compression section that compresses the hydrogen-containing gas from which dehydrogenation products have been removed in the gas-liquid separation section, the compression section being provided between the gas-liquid separation section and the hydrogen purification section.

8. A hydrogen production method for producing hydrogen for distributed power sources, comprising: a dehydrogenation reaction step of generating a hydrogen-containing gas by dehydrogenating a raw material containing a hydride; a gas-liquid separation step of removing a dehydrogenation product from the hydrogen-containing gas produced in the dehydrogenation reaction step; a hydrogen purification step of producing a purified gas containing high-purity hydrogen from the hydrogen-containing gas from which the dehydrogenation product has been removed in the gas-liquid separation step; a degassing step for removing inorganic gases contained in the raw material upstream of the dehydrogenation step from the flow of the raw material, The method for producing hydrogen, wherein the degassing step removes the inorganic gas using a degassing membrane separator.

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