Hydrogen supply system

Abstract

To provide a hydrogen supply system with improved hydrogen production efficiency.SOLUTION: A hydrogen supply system 10 comprises: a water electrolysis system 11 having a water electrolysis device 18 and for generating hydrogen 41 by electrolytically decomposing water 40 and supplying the hydrogen 41 to a hydrogen utilization device 19; a hydrogen recovery system 12 having a hydrogen separation membrane 20 for recovering the hydrogen 41 contained in an exhaust gas 42 discharged from the hydrogen utilization device 19 from the exhaust gas 42 and supplying a recovery hydrogen gas 43 recovered by the hydrogen separation membrane 20 to the hydrogen utilization device 19; and heaters 13, 14 and 36 provided in at least one of the water electrolysis system 11 and the hydrogen supply system 12. A breed gas 44 remaining after the recovery hydrogen gas 43 is recovered by the hydrogen separation membrane 20 contains the hydrogen 41. The breed gas 44 is a heat energy source of the heaters 13, 14, and 36.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hydrogen supply system.

Background Art

[0002] Conventionally, a hydrogen supply system for producing hydrogen described in Patent Document 1 is known. This hydrogen supply system has a cell including an anode, a cathode, and an electrolyte between the anode and the cathode. Water as a supply raw material is pumped as a liquid to a steam generator. The water vapor is preheated by a preheater before being supplied to the cell. Further, the cell described in Patent Document 1 is adapted to operate at a high temperature of 500°C to 1000°C, and in some cases, exceeding 1000°C.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to evaporate water as a supply raw material, if continuously heating liquid water, a large amount of energy is used. Also, a large amount of energy is used to maintain the cell at a high temperature. Therefore, in the above technology, considering the energy supplied to the hydrogen supply system, there is a problem that the production efficiency of hydrogen is low.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a hydrogen supply system with improved hydrogen production efficiency.

Means for Solving the Problems

[0006] One aspect of the present invention is A water electrolysis system (11) has a water electrolysis device (18) including an anode (15), a cathode (16), and an electrolyte (17) disposed between the anode and the cathode, which generates hydrogen (41) by electrolyzing water (40) and supplies the hydrogen to a hydrogen utilization device (19), A hydrogen recovery system (12) includes a hydrogen separation membrane (20) for recovering the hydrogen contained in the exhaust gas (42) discharged from the hydrogen utilization device, and for supplying the recovered hydrogen gas (43) recovered by the hydrogen separation membrane to the hydrogen utilization device. The above water electrolysis system to established 1 Heater ( 13 ) and, The bleed gas (44) remaining after the recovered hydrogen gas is recovered by the hydrogen separation membrane contains the hydrogen, and the bleed gas is the 1 It is considered to be the heat energy source for the heater. 、 The first heater described above heats the water electrolysis device of the water electrolysis system described above. It is located in the hydrogen supply system (10). [Effects of the Invention]

[0007] Since bleed gas contains hydrogen, it can be used as a thermal energy source in a heater installed in at least one of the water electrolysis system and the hydrogen recovery system. Because the hydrogen contained in the bleed gas is produced by the water electrolysis system, when bleed gas is used as the thermal energy source for the heater, as in the hydrogen supply system described above, the amount of energy supplied to the entire hydrogen supply system can be reduced compared to when the thermal energy source for the heater is supplied from an external source. This makes it possible to improve the hydrogen production efficiency relative to the energy supplied to the hydrogen supply system.

[0008] As described above, according to the above embodiment, it is possible to provide a hydrogen supply system with improved hydrogen production efficiency.

[0009] The symbols in parentheses in the claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments later, and do not limit the technical scope of the present invention. [Brief explanation of the drawing]

[0010] [Figure 1] This is a configuration diagram showing the hydrogen supply system of Embodiment 1. [Figure 2] This is a diagram showing the hydrogen supply system of Embodiment 2. [Modes for carrying out the invention]

[0011] (Embodiment 1) 1. Configuration of the hydrogen supply system 10 An embodiment of the hydrogen supply system 10 will be described with reference to Figure 1. In this embodiment, the hydrogen supply system 10 comprises a water electrolysis system 11, a hydrogen recovery system 12, and a first burner 13, a second burner 14, and a heat exchanger 36 as heaters. The water electrolysis system 11 has a water electrolysis device 18 that includes an anode 15, a cathode 16, and an electrolyte 17 disposed between the anode 15 and the cathode 16. The water electrolysis system 11 generates hydrogen 41 by electrolyzing water 40 and supplies the hydrogen 41 to the hydrogen utilization device 19. The hydrogen recovery system 12 has a hydrogen separation membrane 20 that recovers hydrogen 41 contained in exhaust gas 42 discharged from the hydrogen utilization device 19. The hydrogen recovery system 12 supplies the recovered hydrogen gas 43 recovered by the hydrogen separation membrane 20 to the hydrogen utilization device 19. The first burner 13, the second burner 14, and the heat exchanger 36 are provided in the water electrolysis system 11. The remaining bleed gas 44 after the recovered hydrogen gas 43 is recovered by the hydrogen separation membrane 20 contains hydrogen 41. The bleed gas 44 is used as a thermal energy source for the first burner 13, the second burner 14, and the heat exchanger 36.

[0012] The water electrolysis system 11 comprises a water electrolyzer 18, a first burner 13, a power supply 21, air pumps 22, 23, a filter 24, a water pump 25, a heat exchanger 36, a water evaporator 26, a second burner 14, a post-treatment device 27, a compressor 28, and a tank 31. The first burner 13 corresponds to a first heater for heating the water electrolyzer 18 of the water electrolysis system 11. The second burner 14 corresponds to a second heater for heating the water evaporator 26. The heat exchanger 36 corresponds to a heater for heating the water 40.

[0013] The water electrolysis apparatus 18 has an electrolytic cell 32. Figure 1 shows an example of one electrolytic cell 32. The water electrolysis apparatus 18 may be configured to have two or any number of electrolytic cells 32. Each electrolytic cell 32 has an anode 15, a cathode 16, and an electrolyte 17. Air 48, from which impurities have been removed by a filter 24, is supplied to the cathode 16 of the electrolytic cell 32 under pressurization by an air pump 23. Water vapor 45 is supplied to the anode 15 of the electrolytic cell 32. This water vapor 45 is obtained when water 40 supplied to the water evaporator 26 by a water pump 25 is heated by a second burner 14 in the water evaporator 26. The fuel for this second burner 14 is hydrogen 41. The second burner 14 is supplied with bleed gas 44, which will be described later, as fuel. The above fuel corresponds to the heat energy source supplied to the second burner 14. A predetermined voltage is applied to the electrolytic cell 32 from a power supply 21.

[0014] Before being supplied to the water evaporator 26, the water 40 is preheated by the heat exchanger 36. The heat exchanger 36 is supplied with bleed gas 44 as a heat source. The bleed gas 44 is at a relatively high temperature, and the thermal energy it holds corresponds to the thermal energy source for the heat exchanger 36. After the bleed gas 44 supplied to the heat exchanger 36 has transferred its thermal energy to the heat exchanger 36, it is supplied as fuel to the second burner 14. The hydrogen 41 contained in the bleed gas 44 is used as fuel for the second burner 14.

[0015] In this embodiment, the water electrolysis device 18 is composed of a solid oxide electrolysis cell (i.e., SOEC). The water electrolysis device 18 includes a first burner 13. The water electrolysis device 18 is heated to a predetermined temperature by the first burner 13. The temperature of the water electrolysis device 18 is not particularly limited and can be set to any temperature as required. In the case of this embodiment where the water electrolysis device 18 is a solid oxide electrolysis cell, for example, it is set to 500°C to 1000°C. Note that when the water electrolysis device 18 is a proton-conducting ceramic electrolysis cell (i.e., PCEC), it is set to, for example, 500°C to 600°C. When the water electrolysis device 18 is a proton exchange membrane electrolysis cell (i.e., PEM), it is set to, for example, room temperature to 100°C. When the water electrolysis device 18 includes an alkaline electrolyte, it is set to, for example, about 100°C.

[0016] Air 48 pressurized by an air pump 22 is supplied to the first burner 13. Also, hydrogen 41 is supplied to the first burner 13 as fuel. The above fuel corresponds to the heat energy source supplied to the first burner 13. In this embodiment, hydrogen 41 stored in a tank 31 described later or bleed gas 44 described later is supplied to the first burner 13 as fuel. The exhaust gas 46 of the first burner 13 is supplied to a heat exchanger 33 described later and then discharged to the outside.

[0017] Oxygen 49 generated at the cathode 16 of the electrolysis cell 32 is discharged to the outside together with the air 48 supplied to the cathode 16.

[0018] Hydrogen 41 generated at the anode 15 of the electrolysis cell 32 is post-treated in a post-treatment device 27. The post-treatment can adopt any treatment as required. For example, high-purity purification of hydrogen 41, removal of unreacted water 40, removal of impurities, removal of unreacted water vapor 45 by cooling, etc. are performed.

[0019] The hydrogen 41 after the post-treatment is pressurized to a predetermined pressure by the compressor 28 and then stored in the tank 31. A part of the hydrogen 41 stored in the tank 31 is used as fuel for the first burner 13 described above. Also, a part of the hydrogen 41 stored in the tank 31 is supplied to the electrolytic cell 32 together with the water vapor 45 in order to protect the electrolytic cell 32 by making the electrolytic cell 32 in a reducing atmosphere.

[0020] The hydrogen 41 stored in the tank 31 is supplied to the hydrogen utilization device 19 that uses the hydrogen 41. The hydrogen utilization device 19 is not particularly limited. As the hydrogen utilization device 19, for example, any device such as a device for manufacturing a chemical substance using hydrogen 41 as a raw material, a device for performing a reduction process in a reducing atmosphere formed by hydrogen 41, a device for manufacturing and processing a product in a reducing atmosphere formed by hydrogen 41, etc. can be selected. After using the hydrogen 41, the hydrogen utilization device 19 discharges the exhaust gas 42. The exhaust gas 42 contains the hydrogen 41 remaining from the supply from the tank 31. The amount of hydrogen 41 contained in the exhaust gas 42 can vary depending on the type of the hydrogen utilization device 19.

[0021] The exhaust gas 42 discharged from the hydrogen utilization device 19 is supplied to the hydrogen recovery system 12. The hydrogen recovery system 12 includes compressors 29 and 30, a heat exchanger 33, and a hydrogen separation device 34.

[0022] The exhaust gas 42 discharged from the hydrogen utilization device 19 is supplied to the compressor 29 and pressurized to a predetermined pressure by the compressor 29. The exhaust gas 42 pressurized by the compressor 29 is heated by the heat exchanger 33. The heat exchanger 33 is configured to heat the exhaust gas 42 discharged from the hydrogen utilization device 19 by the heat of the exhaust gas 46 from the first burner 13. Thereby, the thermal efficiency of the hydrogen supply system 10 is improved.

[0023] The exhaust gas 42 heated by the heat exchanger 33 is supplied to the hydrogen separation device 34. The hydrogen separation device 34 includes a housing 35 and a hydrogen separation membrane 20 disposed in the housing 35. The shape of the hydrogen separation membrane 20 is not particularly limited, and any shape such as a membrane shape, a cylindrical shape, a hollow fiber shape, etc. can be appropriately selected.

[0024] The material of the hydrogen separation membrane 20 is not particularly limited, and any material can be used as appropriate, such as known palladium, palladium alloy membranes, nickel-niobium-zirconium alloys, amorphous silica, SiC-based membranes, polymer membranes, etc.

[0025] Exhaust gas 42, which has been increased to a predetermined pressure by a compressor 29 and raised to a predetermined temperature by a heat exchanger 33, is injected into the housing 35 of the hydrogen separation device 34. The hydrogen 41 contained in the exhaust gas 42 passes through the hydrogen separation membrane 20 located inside the housing 35. As a result, recovered hydrogen gas 43 is recovered from the exhaust gas 42. The recovered hydrogen gas 43 contains hydrogen 41 at a higher concentration than the exhaust gas 42. The recovered hydrogen gas 43 is pressurized by a compressor 30 and then supplied to a tank 31. The recovered hydrogen gas 43 supplied to the tank 31 is then supplied again to the hydrogen utilization device 19. In this way, hydrogen 41 can be reused according to this embodiment.

[0026] On the other hand, of the exhaust gas 42 injected into the enclosure 35, the gas that did not pass through the hydrogen separation membrane 20 is discharged from the hydrogen separation device 34 as bleed gas 44. The bleed gas 44 contains gases other than hydrogen 41, as well as hydrogen 41 that could not pass through the hydrogen separation membrane 20. The proportion of hydrogen 41 in the bleed gas 44 is not particularly limited, and it is designed to contain hydrogen 41 in any proportion.

[0027] The bleed gas 44 is supplied to the first burner 13 and the second burner 14. The hydrogen 41 contained in the bleed gas 44 is used as fuel for the first burner 13 and the second burner 14.

[0028] The arrows connecting the various components shown in Figure 1 indicate the flow paths of liquids or gases, and these paths are constructed using piping, etc. The same applies to Figure 2, which will be discussed later.

[0029] 2. Effects Next, the effects of this embodiment will be explained. In this embodiment, the bleed gas 44 remaining after the recovered hydrogen gas 43 is recovered by the hydrogen separation membrane 20 contains hydrogen 41. Therefore, the bleed gas 44 can be used as a thermal energy source for the first burner 13 and the second burner 14 provided in the water electrolysis system 11. Since the hydrogen 41 contained in the bleed gas 44 is produced by the water electrolysis system 11, the amount of energy supplied to the entire hydrogen supply system 10 can be reduced compared to when the thermal energy sources for the first burner 13, the second burner 14 and the heat exchanger 36 are supplied from an external source. In addition, since the bleed gas 44 is relatively hot, it can be used as a thermal energy source for the heat exchanger 36. This reduces the amount of energy supplied to the entire hydrogen supply system 10 compared to when the thermal energy source for the heat exchanger 36 is supplied from an external source. As a result, the production efficiency of hydrogen 41 relative to the energy supplied to the hydrogen supply system 10 can be improved.

[0030] Furthermore, since the recovered hydrogen gas 43 can be supplied to the hydrogen utilization device 19, the amount of hydrogen 41 produced for supply to the hydrogen utilization device 19 can be reduced. This reduces the system size and running costs of the hydrogen supply system 10, and thus reduces the production cost of hydrogen 41.

[0031] Since the bleed gas 44 is used as fuel for the first burner 13 and the second burner 14, the amount of hydrogen 41 that is discarded can be reduced. As a result, the equipment required to discard the hydrogen 41 contained in the bleed gas 44 becomes unnecessary, and the overall exhaust treatment can be simplified.

[0032] Since the bleed gas 44 is supplied to the heat exchanger 36 to heat the water 40, the thermal energy held by the bleed gas 44 itself can be used as a heat source. This improves the production efficiency of hydrogen 41. Furthermore, even after the thermal energy has been transferred to the heat exchanger 36, the bleed gas 44 still contains hydrogen 41 and is therefore supplied to the second burner 14 as fuel. This further improves the production efficiency of hydrogen 41. However, the bleed gas 44 may also be supplied to a heat exchanger for heating any object, such as a device or gas that needs to be heated, and used as a thermal energy source for heating the object.

[0033] In this embodiment, the first burner 13 is provided in the water electrolysis system 11. This improves the hydrogen production efficiency of the water electrolysis system 11, and therefore improves the hydrogen production efficiency of the hydrogen supply system 10.

[0034] In this embodiment, the first burner 13 is configured to heat the water electrolysis device 18 of the water electrolysis system 11. From the viewpoint of hydrogen 41 production efficiency, it is preferable that the water electrolysis device 18 be maintained at a relatively high temperature. By using bleed gas 44 as a thermal energy source for the first burner 13 to heat the water electrolysis device 18, the hydrogen 41 production efficiency in the water electrolysis system 11 can be improved compared to when the thermal energy source for the first burner 13 is supplied from an external source. This improves the hydrogen 41 production efficiency in the hydrogen supply system 10.

[0035] The water electrolysis system 11 has a water evaporator 26 for evaporating water 40, and the second burner 14 is configured to heat the water evaporator 26. When evaporating water 40, it is necessary to supply thermal energy to the water 40 that corresponds to the latent heat of vaporization. In order to continuously evaporate water 40 in the water evaporator 26, thermal energy must be continuously supplied to the water 40, so the thermal energy supplied to the water evaporator 26 is relatively large. By using bleed gas 44 as a thermal energy source for the second burner 14 that heats the water evaporator 26, the production efficiency of hydrogen 41 in the water electrolysis system 11 can be improved compared to when the thermal energy source for the second burner 14 is supplied from an external source. As a result, the production efficiency of hydrogen 41 in the hydrogen supply system 10 can be improved.

[0036] In this embodiment, a solid oxide electrolytic cell is used in the water electrolysis device 18. Since solid oxide electrolytic cells are used at relatively high temperatures, such as 700°C or higher, a relatively large amount of thermal energy is required when heating them. In a hydrogen supply system 10 using such a solid oxide electrolytic cell, using bleed gas 44 as a thermal energy source is particularly effective.

[0037] (Embodiment 2) Next, the hydrogen supply system 50 of Embodiment 2 will be described with reference to Figure 2. In this embodiment, a third burner 51 is located in the heat exchanger 33 of the hydrogen recovery system 12. The heat exchanger 33 is heated to a predetermined temperature by the third burner 51. As a result, the exhaust gas 42 passing through the heat exchanger 33 is heated to a predetermined temperature before it flows to the hydrogen separation membrane 20. The third burner 51 corresponds to a third heater that heats the exhaust gas 42 before it flows to the hydrogen separation membrane 20. Bleed gas 44 is supplied to the third burner 51 as fuel. The above fuel corresponds to a thermal energy source supplied to the third burner 51.

[0038] Furthermore, in this embodiment, a fourth burner 52 is provided in the hydrogen separation unit 34. The fourth burner 52 heats the hydrogen separation membrane 20 provided in the hydrogen separation unit 34. The fourth burner 52 corresponds to a heater provided in the hydrogen recovery system. Bleed gas 44 is supplied to the fourth burner 52 as fuel. The above fuel corresponds to a thermal energy source supplied to the fourth burner 52.

[0039] However, although this embodiment includes a configuration with a third burner 51 and a fourth burner 52, a configuration with only one of the third burner or the fourth burner may also be used.

[0040] In this configuration, the recovered hydrogen gas 43 separated by the hydrogen separation device 34 is combined with hydrogen 41 after post-treatment is performed in the post-treatment device 27 and before being supplied to the compressor 28. As a result, the compressor 28 can be used for both the hydrogen 41 produced by the water electrolysis device 18 and the recovered hydrogen gas 43 recovered by the hydrogen separation device 34, thereby reducing the production cost of hydrogen 41.

[0041] Furthermore, in this embodiment, the exhaust gas 47 from the first burner 13 is not supplied to the heat exchanger 33 but is discharged to the outside. However, the exhaust gas 47 may be supplied to a heat exchanger other than the heat exchanger 33 to heat other equipment not shown.

[0042] Furthermore, in this embodiment, the heat exchanger 36 for heating the water 40 is omitted.

[0043] The configuration other than that described above is substantially the same as in Embodiment 1, so the same reference numerals are used for the same components, and redundant explanations are omitted.

[0044] In order to recover hydrogen 41 from exhaust gas 42 using the hydrogen separation membrane 20, it is preferable to heat the exhaust gas 42 to a predetermined temperature. The temperature of the exhaust gas 42 is set to, for example, 300 to 400°C. By using bleed gas 44 as a thermal energy source for the third burner 51 used to heat the exhaust gas 42, the production efficiency of hydrogen 41 in the hydrogen supply system 10 can be improved compared to when the thermal energy source for the third burner 51 is supplied from an external source.

[0045] Furthermore, heating the hydrogen separation membrane 20 can improve the separation efficiency of the recovered hydrogen gas 43. By using bleed gas 44 as a thermal energy source for the fourth burner 52 used to heat the hydrogen separation membrane 20, the production efficiency of hydrogen 41 in the hydrogen supply system 10 can be improved compared to when the thermal energy source for the fourth burner 52 is supplied from an external source.

[0046] The present invention is not limited to the embodiments described above, and can be applied to various embodiments without departing from its spirit.

[0047] In this embodiment, the water electrolysis device 18 is configured to include a solid oxide type electrolytic cell, but it is not limited to this configuration. For example, it may also be configured to include a proton-conducting type ceramic electrolytic cell. Since proton-conducting type ceramic electrolytic cells are used at relatively high temperatures, such as 500°C to 600°C, a relatively large amount of thermal energy is required when heating them. In a hydrogen supply system 10 using such a proton-conducting type ceramic electrolytic cell, using bleed gas 44 as a thermal energy source is particularly effective. Furthermore, the water electrolysis device 18 may also be equipped with a proton exchange membrane (i.e., PEM), or it may be configured to use an alkaline water electrolyte.

[0048] In Embodiment 2, the bleed gas 44 is supplied to the first to fourth burners 13, 14, 51, and 52 as a thermal energy source. However, the bleed gas 44 may also be supplied as fuel to the igniter, or as fuel to other combustion devices. [Explanation of symbols]

[0049] 10, 50…Hydrogen supply system, 11…Water electrolysis system, 12…Hydrogen recovery system, 13…First burner, 14…Second burner, 15…Anode, 16…Cathode, 17…Electrolyte, 18…Water electrolysis device, 19…Hydrogen utilization device, 20…Hydrogen separation membrane, 36…Heat exchanger, 40…Water, 41…Hydrogen, 42…Exhaust gas, 43…Recovered hydrogen gas, 44…Bleed gas, 51…Third burner, 52…Fourth burner

Claims

1. A water electrolysis system (11) comprises a water electrolysis apparatus (18) including an anode (15), a cathode (16), and an electrolyte (17) disposed between the anode and the cathode, which generates hydrogen (41) by electrolyzing water (40) and supplies the hydrogen to a hydrogen utilization apparatus (19), A hydrogen recovery system (12) has a hydrogen separation membrane (20) that recovers the hydrogen contained in the exhaust gas (42) discharged from the hydrogen utilization device, and supplies the recovered hydrogen gas (43) recovered by the hydrogen separation membrane to the hydrogen utilization device. The water electrolysis system described above includes a first heater (13), The bleed gas (44) remaining after the recovered hydrogen gas is recovered by the hydrogen separation membrane contains the hydrogen, and this bleed gas is used as the thermal energy source for the first heater. The first heater described above is a hydrogen supply system (10) that heats the water electrolysis apparatus of the water electrolysis system.

2. The above water electrolysis system has a water evaporator (26) for evaporating the water, The hydrogen supply system further includes a second heater (14) for heating the water evaporator. The hydrogen supply system according to claim 1, wherein the bleed gas is used as a thermal energy source for the second heater.

3. The hydrogen supply system further comprises a third heater (51) provided in the hydrogen recovery system, The above-mentioned bleed gas is used as the thermal energy source for the third heater. The hydrogen supply system according to claim 2, wherein the third heater heats the exhaust gas before it is passed through the hydrogen separation membrane.

4. The hydrogen supply system further comprises a third heater (51) provided in the hydrogen recovery system, The above-mentioned bleed gas is used as the thermal energy source for the third heater. The hydrogen supply system according to claim 1, wherein the third heater heats the exhaust gas before it is passed through the hydrogen separation membrane.

5. The hydrogen supply system according to any one of claims 1 to 4, wherein the water electrolysis apparatus is a solid oxide type electrolytic cell.

6. The above-mentioned water electrolysis apparatus is a proton-conducting ceramic electrolytic cell, and the hydrogen supply system is according to any one of claims 1 to 4.

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