Hydrogen production equipment and operation method for hydrogen production equipment

Abstract

According to the present invention, hydrogen production equipment comprises: a first electrolysis device that includes a first electrolysis tank for electrolyzing water, a first gas / liquid separator to which gas that has been generated at the first electrolysis tank is led, a first circulation line for circulating an electrolyte solution between the first electrolysis tank and the first gas / liquid separator, and a first circulation pump that is provided on the first circulation line; and a second electrolysis device that similarly includes a second electrolysis tank, a second gas / liquid separator, a second circulation line, and a second circulation pump. The hydrogen production equipment also comprises: a branch line that connects a portion of the first circulation line that is downstream of an outlet of the first electrolysis tank and upstream of the first circulation pump and a portion of the second circulation line that is downstream of an outlet of the second electrolysis tank and upstream of the second circulation pump; and a return line that connects a portion of the second circulation line that is downstream of the second circulation pump and upstream of an inlet of the second electrolysis tank and a portion of the first circulation line that is downstream of the first circulation pump and upstream of an inlet of the first electrolysis tank.

Description

Hydrogen production equipment and operation method of hydrogen production equipment

[0001] This disclosure relates to hydrogen production equipment and an operation method of hydrogen production equipment. This application claims priority based on Japanese Patent Application No. 2024-221664 filed with the Japan Patent Office on December 18, 2024, and the content thereof is incorporated herein by reference.

[0002] A water electrolysis device is used to produce hydrogen. Generally, a water electrolysis device includes an electrolytic cell (cell stack) and auxiliary equipment such as an electrolytic solution circulation system and a gas-liquid separator. For the purpose of supplying a sufficient amount of hydrogen to equipment (such as a gas turbine) that consumes a large amount of hydrogen, multiple water electrolysis devices may be operated simultaneously in a hydrogen production facility (plant).

[0003] Patent Document 1 describes an alkaline water electrolysis system including a plurality of electrolytic cells. This alkaline water electrolysis system is configured to determine the number of electrolytic cells to be operated among the plurality of electrolytic cells according to the power supplied to the alkaline water electrolysis system.

[0004] Japanese Patent No. 7441332

[0005] In a hydrogen production facility including a plurality of water electrolysis devices, when the available power supply is low, it is necessary to stop some of the plurality of water electrolysis devices. In such a case, there is a tendency for the operation to be uneconomical with respect to the capital investment.

[0006] In view of the above circumstances, at least one embodiment of the present invention aims to provide a hydrogen production facility and an operation method of a hydrogen production facility that can efficiently produce hydrogen when the power supply to the hydrogen production facility is low in a hydrogen production facility including a plurality of water electrolysis devices.

[0007] A hydrogen production apparatus according to at least one embodiment of the present invention comprises a first electrolytic device and a second electrolytic device, the first electrolytic device includes a first electrolytic cell for electrolyzing water, a first gas-liquid separator through which the gas produced in the first electrolytic cell is introduced, a first circulation line for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump provided in the first circulation line, the second electrolytic device includes a second electrolytic cell for electrolyzing water, a second gas-liquid separator through which the gas produced in the second electrolytic cell is introduced, a second circulation line for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump provided in the second circulation line, and a diversion line for merging at least a portion of the electrolyte flowing in the portion of the first circulation line downstream of the outlet of the first electrolytic cell and upstream of the first circulation pump into the portion of the second circulation line downstream of the outlet of the second electrolytic cell and upstream of the second circulation pump, The system includes a return line for merging at least a portion of the electrolyte flowing in the portion of the second circulation line downstream of the second circulation pump and upstream of the inlet of the second electrolytic cell with the portion of the first circulation line downstream of the first circulation pump and upstream of the inlet of the first electrolytic cell.

[0008] Furthermore, an operating method for a hydrogen production facility according to at least one embodiment of the present invention is the operating method for a hydrogen production facility described above, comprising the step of operating the second circulation pump while hydrogen is being produced by the first electrolytic device with the second electrolytic cell stopped, thereby circulating a portion of the electrolyte flowing through the first circulation line through the diversion line and the return line.

[0009] Furthermore, a hydrogen production apparatus according to at least one embodiment of the present invention comprises at least a first electrolytic device and a second electrolytic device, the first electrolytic device includes a first electrolytic cell for electrolyzing water, a first gas-liquid separator through which the gas produced in the first electrolytic cell is introduced, a first circulation line for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump provided in the first circulation line, the second electrolytic device includes a second electrolytic cell for electrolyzing water, a second gas-liquid separator through which the gas produced in the second electrolytic cell is introduced, a second circulation line for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump provided in the second circulation line, the first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator, the first circulation pump and the second circulation pump include a common single circulation pump, and the first circulation line is The second circulation line includes a first outlet line for guiding the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator, and a first inlet line for returning the electrolyte from the single gas-liquid separator to the first electrolytic cell, the second circulation line includes a second outlet line for guiding the gas and electrolyte from the second electrolytic cell to the single gas-liquid separator, and a second inlet line for returning the electrolyte from the single gas-liquid separator to the second electrolytic cell, the first outlet line and the second outlet line have a common confluence point and include a common outlet line downstream of the confluence point, the first inlet line and the second inlet line have a common branching point and include a common inlet line upstream of the branching point, and the inlet valve of the second electrolytic cell is configured to be closed when hydrogen is being produced by the first electrolytic device while the second electrolytic cell is stopped.

[0010] Furthermore, an operating method for a hydrogen production facility according to at least one embodiment of the present invention is an operating method for a hydrogen production facility comprising at least a first electrolytic device and a second electrolytic device, wherein the first electrolytic device includes a first electrolytic cell for electrolyzing water, a first gas-liquid separator through which the gas produced in the first electrolytic cell is introduced, a first circulation line for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump provided in the first circulation line, wherein the second electrolytic device includes a second electrolytic cell for electrolyzing water, a second gas-liquid separator through which the gas produced in the second electrolytic cell is introduced, a second circulation line for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump provided in the second circulation line, wherein the first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator, the first circulation pump and the second circulation pump include a common single circulation pump, and the first circulation line is The second circulation line includes a first outlet line for leading the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator, and a first inlet line for returning the electrolyte from the single gas-liquid separator to the first electrolytic cell, the second circulation line includes a second outlet line for leading the gas and electrolyte from the second electrolytic cell to the single gas-liquid separator, and a second inlet line for returning the electrolyte from the single gas-liquid separator to the second electrolytic cell, the first outlet line and the second outlet line have a common confluence point and include a common outlet line downstream of the confluence point, the first inlet line and the second inlet line have a common branching point and include a common inlet line upstream of the branching point, and the procedure includes the steps of closing the inlet valve of the second electrolytic cell and operating the common single circulation pump while hydrogen is being produced by the first electrolytic device with the second electrolytic cell stopped.

[0011] According to at least one embodiment of the present invention, a hydrogen production facility including a plurality of water electrolyzers is provided that can efficiently produce hydrogen when the power supplied to the hydrogen production facility is low, and a method for operating the hydrogen production facility is provided.

[0012] This is a schematic diagram of a hydrogen production facility according to one embodiment. This is a schematic diagram of a hydrogen production facility according to one embodiment. This is a schematic diagram of a hydrogen production facility according to one embodiment. This is a schematic diagram of a hydrogen production facility according to one embodiment. This is a schematic diagram of a hydrogen production facility according to one embodiment. This is a schematic diagram of a hydrogen production facility according to one embodiment.

[0013] Hereinafter, several embodiments of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0014] (Configuration of Hydrogen Production Equipment) Figures 1 to 5 are schematic diagrams of a hydrogen production equipment according to one embodiment. As shown in Figures 1 to 5, the hydrogen production equipment 1 according to several embodiments comprises a first electrolytic device 2A including a first electrolytic cell (cell stack) 4A for electrolyzing water, and a second electrolytic device 2B including a second electrolytic cell (cell stack) 4B for electrolyzing water.

[0015] The first electrolytic apparatus 2A includes, in addition to the first electrolytic cell 4A, first gas-liquid separators 16A and 36A on the cathode and anode sides to which hydrogen gas and oxygen gas generated in the first electrolytic cell 4A are respectively introduced, first circulation lines 10A and 30A for circulating the electrolyte between the first electrolytic cell 4A and the first gas-liquid separators 16A and 36A, respectively, and first circulation pumps 22A and 42A provided on the first circulation lines 10A and 30A, respectively.

[0016] The first electrolytic apparatus 2A, which includes the first electrolytic cell 4A, is supplied with water for electrolysis (makeup water; pure water, etc.) via a makeup water line 6A. The makeup water line 6A may be connected to either the first gas-liquid separator 16A or 36A. In the illustrated embodiment, the makeup water line 6A is connected to the cathode-side first gas-liquid separator 16A.

[0017] In the first electrolytic device 2A, a voltage is applied between the electrodes provided in the first electrolytic cell 4A, causing electrolysis of the water in the first electrolytic cell 4A. Hydrogen gas is generated at the cathode and oxygen gas is generated at the anode. The water in the first electrolytic cell 4A is typically water in which an electrolyte is dissolved (electrolyte solution or electrolyte liquid). The electrolyte may be an alkaline substance such as potassium hydroxide (KOH).

[0018] Hydrogen gas and oxygen gas discharged from the first electrolytic cell 4A along with the electrolyte are introduced to the first gas-liquid separators 16A and 36A via the first circulation lines 10A and 30A in the form of a gas-liquid two-phase flow. In the first gas-liquid separators 16A and 36A, this two-phase flow is separated into gas (hydrogen gas or oxygen gas) and liquid (electrolyte).

[0019] The gas (hydrogen gas or oxygen gas) separated from the two-phase flow in the first gas-liquid separators 16A and 36A is discharged from the first gas-liquid separators 16A and 36A via the first discharge lines 18A and 38A. The hydrogen gas or oxygen gas discharged from the first discharge lines 18A and 38A may be supplied to a hydrogen consumption facility (e.g., a gas turbine) or an oxygen consumption facility.

[0020] The first circulation lines 10A and 30A include outlet lines 12A and 32A for guiding hydrogen gas and oxygen gas discharged together with the electrolyte from the outlet of the first electrolytic cell 4A to the first gas-liquid separators 16A and 36A, respectively, and inlet lines 14A and 34A for guiding the electrolyte separated from the two-phase flow of electrolyte and gas in the first gas-liquid separators 16A and 36A to the inlet of the first electrolytic cell 4A.

[0021] The outlet lines 12A and 32A may be provided with outlet valves 13A and 33A for adjusting the flow rate of the electrolyte in the outlet lines 12A and 32A. The inlet lines 14A and 34A may be provided with inlet valves 15A and 35A for adjusting the flow rate of the electrolyte in the inlet lines 14A and 34A.

[0022] The first circulation lines 10A and 30A are each provided with first circulation pumps 22A and 42A, respectively, for circulating the electrolyte through the first circulation lines 10A and 30A. The first circulation pumps 22A and 42A may be configured to be driven by motors (not shown). In some embodiments, as shown in Figures 1 to 5, the first circulation pumps 22A and 42A are provided in the inlet lines 14A and 34A of the first circulation lines 10A and 30A, respectively.

[0023] The first circulation lines 10A and 30A are each provided with first coolers 20A and 40A, respectively, to cool the electrolyte flowing through the first circulation lines 10A and 30A by heat exchange with the cooling medium. In some embodiments, as shown in Figures 1 to 5, the first coolers 20A and 40A are located in the inlet lines 14A and 34A of the first circulation lines 10A and 30A, downstream of the first gas-liquid separators 16A and 36A and upstream of the first circulation pumps 22A and 42A.

[0024] As shown in Figure 1, the first coolers 20A and 40A may be supplied with a cooling medium via cooling medium lines 92A and 94A. Cooling medium lines 92A and 94A may be provided with cooling medium valves 93A and 95A for adjusting the flow rate of the cooling medium in the cooling medium lines 92A and 94A.

[0025] As shown in Figure 1, the first electrolytic device 2A may include a temperature control unit 90A for controlling the temperature of the electrolyte at the outlet of the first electrolytic cell 4A. The temperature control unit 90A may be configured to adjust the amount of cooling medium supplied to the first coolers 20A and 40A so that the temperature of the electrolyte at the outlet of the first electrolytic cell 4A is within a predetermined range. The temperature control unit 90A may include temperature sensors 96A and 97A provided in the first circulation lines 10A and 30A for measuring the temperature of the electrolyte at the outlet of the first electrolytic cell 4A, and the aforementioned cooling medium valves 93A and 95A configured to adjust the flow rate of the cooling medium based on the detection results of the temperature sensors 96A and 97A.

[0026] Although only Figure 1 shows the cooling medium lines 92A, 94A and the temperature control unit 90A, the exemplary embodiments shown in Figures 2 to 5 may also similarly include the cooling medium lines 92A, 94A and the temperature control unit 90A.

[0027] The second electrolytic apparatus 2B includes, in addition to the second electrolytic cell 4B, second gas-liquid separators 16B and 36B on the cathode and anode sides to which hydrogen gas and oxygen gas generated in the second electrolytic cell 4B are introduced, respectively; second circulation lines 10B and 30B for circulating the electrolyte between the second electrolytic cell 4B and the second gas-liquid separators 16B and 36B, respectively; and second circulation pumps 22B and 42B provided on the second circulation lines 10B and 30B, respectively.

[0028] The second electrolytic device 2B may have the same configuration as the first electrolytic device 2A described above. That is, the second electrolytic device 2B may include a makeup water line 6B for supplying water to the second circulation lines 10B and 30B, second discharge lines 18B and 38B for discharging gas from the second gas-liquid separators 16B and 36B, outlet lines 12B and 32B and inlet lines 14B and 34B of the second circulation lines 10B and 30B, outlet valves 13B and 33B provided on the outlet lines 12B and 32B, inlet valves 15B and 35B provided on the inlet lines 14B and 34B, and / or second coolers 20B and 40B provided on the second circulation lines 10B and 30B.

[0029] Furthermore, the second electrolytic apparatus 2B may include a cooling medium line (not shown) for supplying a cooling medium to the second coolers 20B and 40B, and may also include a temperature control unit (not shown) for controlling the temperature of the electrolyte at the outlet of the second electrolytic cell 4B.

[0030] Furthermore, each component of the second electrolytic apparatus 2B (second electrolytic cell 4B, second gas-liquid separators 16B, 36B, second circulation lines 10B, 30B, second circulation pumps 22B, 42B, etc.) may have the same configuration as the corresponding components of the first electrolytic apparatus 2A.

[0031] In the exemplary embodiment shown in Figure 5, the cathode-side first gas-liquid separator 16A and the cathode-side second gas-liquid separator 16B include a common single cathode-side gas-liquid separator 16. The anode-side first gas-liquid separator 36A and the anode-side second gas-liquid separator 36B also include a common single anode-side gas-liquid separator 36. Discharge lines 18 (first discharge line 18A and second discharge line 18B) are connected to the gas-liquid separator 16. Discharge lines 38 (first discharge line 38A and second discharge line 38B) are connected to the gas-liquid separator 36.

[0032] Furthermore, in the exemplary embodiment shown in Figure 5, the first circulation lines 10A, 30A include first outlet lines 12A, 32A for leading the gas and electrolyte from the first electrolytic cell 4A to the aforementioned single gas-liquid separators 16, 36, and first inlet lines 14A, 34A for returning the electrolyte from the single gas-liquid separators 16, 36 back to the first electrolytic cell 4A. The second circulation lines 10B, 30B include second outlet lines 12B, 32B for leading the gas and electrolyte from the second electrolytic cell 4B to the aforementioned single gas-liquid separators 16, 36, and second inlet lines 14B, 34B for returning the electrolyte from the single gas-liquid separators 16, 36 back to the second electrolytic cell 4B.

[0033] The first exit line 12A and the second exit line 12B have a common confluence point P1 and include a common exit line 12 downstream of the confluence point P1. The first exit line 32A and the second exit line 32B have a common confluence point P3 and include a common exit line 32 downstream of the confluence point P3. The first inlet line 14A and the second inlet line 14B have a common branching point P2 and include a common inlet line 14 upstream of the branching point P2. The first inlet line 34A and the second inlet line 34B have a common branching point P4 and include a common inlet line 34 upstream of the branching point P4.

[0034] A cooler 20 (first cooler 20A and second cooler 20B) is provided on the common inlet line 14. A cooler 40 (first cooler 40A and second cooler 40B) is provided on the common inlet line 34.

[0035] As shown in Figures 1 to 5, several embodiments of the hydrogen production equipment 1 include diversion lines 50, 60 and return lines 54, 64.

[0036] The diversion lines 50 and 60 are configured to divert at least a portion of the electrolyte flowing in the first circulation lines 10A and 30A downstream of the outlet of the first electrolytic cell 4A and upstream of the first circulation pumps 22A and 42A to the second circulation lines 10B and 30B downstream of the outlet of the second electrolytic cell 4B and upstream of the second circulation pumps 22B and 42B.

[0037] The return lines 54 and 64 are configured to merge at least a portion of the electrolyte flowing in the second circulation lines 10B and 30B downstream of the second circulation pumps 22B and 42B and upstream of the inlet of the second electrolytic cell 4B with the first circulation lines 10A and 30A downstream of the first circulation pumps 22A and 42A and upstream of the inlet of the first electrolytic cell 4A.

[0038] Furthermore, the diversion lines 50, 60 and / or the return lines 54, 64 may each be provided with valves 52, 62, 56, and 66 for adjusting the flow rate of the electrolyte in each line.

[0039] In the exemplary embodiments shown in Figures 1 to 4, the diversion lines 50 and 60 have first ends 50a and 60a connected to the first circulation lines 10A and 30A downstream of the outlet of the first electrolytic cell 4A and upstream of the first circulation pumps 22A and 42A, and second ends 50b and 60b connected to the second circulation lines 10B and 30B downstream of the outlet of the second electrolytic cell 4B and upstream of the second circulation pumps 22B and 42B. The return lines 54 and 64 have first ends 54a and 64a connected to the second circulation lines 10B and 30B downstream of the second circulation pumps 22B and 42B and upstream of the inlet of the second electrolytic cell 4B, and second ends 54b and 64b connected to the first circulation lines 10A and 30A downstream of the first circulation pumps 22A and 42A and upstream of the inlet of the first electrolytic cell 4A.

[0040] In the exemplary embodiments shown in Figures 1 to 3, the first ends 50a, 60a of the diversion lines 50, 60 are connected to the first circulation lines 10A, 30A downstream of the first gas-liquid separators 16A, 36A and upstream of the first circulation pumps 22A, 42A, while the second ends 50b, 60b of the diversion lines 50, 60 are connected to the second circulation lines 10B, 30B downstream of the second gas-liquid separators 16B, 36B and upstream of the second circulation pumps 22B, 42B.

[0041] In the exemplary embodiment shown in Figure 4, the first ends 50a, 60a of the diversion lines 50, 60 are connected to a portion of the first circulation lines 10A, 30A downstream of the outlet of the first electrolytic cell 4A and upstream of the first gas-liquid separators 16A, 36A, while the second ends 50b, 60b of the diversion lines 50, 60 are connected to the second gas-liquid separators 16B, 36B. In some embodiments, the second ends 50b, 60b of the diversion lines 50, 60 may be connected to a portion of the second circulation lines 10B, 30B downstream of the outlet of the second electrolytic cell 4B and upstream of the second gas-liquid separators 16B, 36B.

[0042] In the exemplary embodiment shown in Figure 5, the diversion lines 50 and 60 include portions of the second inlet lines 14B and 34B that are downstream of the branching points P2 and P4 and upstream of the second circulation pumps 22B and 42B, while the return lines 54 and 64 have first ends 54a and 64a connected to portions of the second inlet lines 14B and 34B that are downstream of the second circulation pumps 22B and 42B and upstream of the inlet of the second electrolytic cell 4B, and second ends 54b and 64b connected to portions of the first inlet lines 14A and 34A that are downstream of the first circulation pumps 22A and 42A and upstream of the inlet of the first electrolytic cell 4A.

[0043] In the above-described embodiment, in the hydrogen production facility 1 including a plurality of water electrolysis devices (the first electrolysis device 2A and the second electrolysis device 2B), the above-described diversion lines 50, 60 and return lines 54, 64 are provided. Therefore, a part of the electrolytic solution flowing through the upstream portions of the first circulation pumps 22A, 42A in the first circulation lines 10A, 30A can be guided to the second circulation pumps 22B, 42B via the diversion lines 50, 60 and returned to the downstream portions of the first circulation pumps 22A, 42A in the first circulation lines 10A, 30A via the return lines 54, 64.

[0044] Therefore, in a state where the second electrolytic cell 4B is stopped (that is, a state where hydrogen production in the second electrolysis device 2B is stopped), by operating the second circulation pumps 22B, 42B of the second electrolysis device 2B, as described above, a part of the electrolytic solution flowing through the upstream portions of the first circulation pumps 22A, 42A in the first circulation lines 10A, 30A is guided to the second circulation pumps 22B, 42B via the diversion lines 50, 60 and returned to the downstream portions of the first circulation pumps 22A, 42A in the first circulation lines 10A, 30A via the return lines 54, 64. As a result, the flow rate of the electrolytic solution in the first electrolytic cell 4A increases. At this time, for example, if the temperature of the electrolytic solution is controlled by the temperature adjustment unit 90A so that the temperature of the electrolytic solution at the inlet of the first electrolytic cell 4A is within a predetermined range (or becomes a predetermined value), the average temperature of the electrolytic solution in the first electrolytic cell 4A increases, and thereby, the electrolysis efficiency (that is, the hydrogen production efficiency) in the first electrolytic cell 4A can be increased. Therefore, according to the above-described embodiment, when the power supplied to the hydrogen production facility 1 is small, the auxiliary machines (the second circulation pumps 22B, 42B, etc.) of the stopped second electrolytic cell 4B can be effectively utilized to efficiently produce hydrogen.

[0045] When the second electrolytic cell 4B is stopped, the valves 13B, 15B, 33B, and 35B provided in the second circulation lines 10B and 30B are closed, and the circulation of electrolyte in the second circulation lines 10B and 30B is stopped. On the other hand, when the second electrolytic cell 4B is in operation (when hydrogen is produced in the second electrolytic device 2B), the valves 13B, 15B, 33B, and 35B provided in the second circulation lines 10B and 30B are open, and the electrolyte circulates through the second circulation lines 10B and 30B. Also, when the first electrolytic cell 4A is in operation (when hydrogen is produced in the first electrolytic device 2A), the valves 13A, 15A, 33A, and 35A provided in the first circulation lines 10A and 30A are open, and the electrolyte circulates through the first circulation lines 10A and 30A.

[0046] Furthermore, as described above, when the electrolyte is circulated through the diversion lines 50, 60 and the return lines 54, 64, the valves 52, 56, 62, 66 provided in the diversion lines 50, 60 and the return lines 54, 64 are set to the open state.

[0047] In the exemplary embodiments shown in Figures 1 and 3, the first ends 50a, 60a of the diversion lines 50, 60 are connected to the portion of the first circulation lines 10A, 30A downstream of the first coolers 20A, 40A and upstream of the first circulation pumps 22A, 42A, while the second ends 50b, 60b of the diversion lines 50, 60 are connected to the portion of the second circulation lines 10B, 30B downstream of the second coolers 20B, 40B and upstream of the second circulation pumps 22B, 42B.

[0048] According to the above-described embodiment, in a state where the second electrolytic cell 4B is stopped (i.e., a state where hydrogen production in the second electrolytic device 2B is stopped), by operating the second circulation pumps 22B and 42B of the second electrolytic device 2B, a part of the electrolytic solution flowing through a part on the downstream side of the first coolers 20A and 40A and on the upstream side of the first circulation pumps 22A and 42A in the first circulation lines 10A and 30A is guided through the shunt lines 50 and 60 to the second circulation pumps 22B and 42B through a part on the downstream side of the second coolers 20B and 40B in the second circulation lines 10B and 30B (i.e., without passing through the second coolers 20B and 40B), and is returned to a part on the downstream side of the first circulation pumps 22A and 42A in the first circulation lines 10A and 30A through the return lines 54 and 64. Therefore, without using the second coolers 20B and 40B in the second electrolytic device 2B, the flow rate of the electrolytic solution in the first electrolytic cell 4A can be increased, and the average temperature of the electrolytic solution in the first electrolytic cell 4A can be increased. Thereby, the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell 4A can be enhanced.

[0049] In some embodiments, for example, as shown in FIG. 3, the hydrogen production facility 1 includes gas-liquid separation drums 72 and 82 provided in the first discharge lines 18A and 28A for discharging gas from the first gas-liquid separators 16A and 36A, and a flow rate adjustment unit for adjusting the flow rate of the electrolytic solution in the shunt lines 50 and 60 or the return lines 54 and 64 according to the liquid level in the gas-liquid separation drums 72 and 82. The flow rate adjustment unit may be configured to decrease the flow rate of the electrolytic solution in the shunt lines 50 and 60 or the return lines 54 and 64 when the liquid level in the gas-liquid separation drums 72 and 82 exceeds a predetermined value.

[0050] In the exemplary embodiment shown in FIG. 3, the flow rate adjustment unit is configured to adjust the flow rate of the electrolytic solution in the shunt lines 50 and 60 according to the liquid level in the gas-liquid separation drums 72 and 82. The flow rate adjustment unit includes liquid level gauges 74 and 84, and valves 52 and 62 provided in the shunt lines 50 and 60 configured to adjust the opening degree according to the detection results of the liquid level gauges 74 and 84.

[0051] As shown in Figure 3, demisters 70 and 80 may be provided upstream of the gas-liquid separation drums 72 and 82 in the discharge lines 18A and 38A to remove droplets contained in the gas discharged from the discharge lines 18A and 38A. Also, as shown in Figure 3, the gas-liquid separation drums 72 and 82 may be provided with discharge sections 76 and 86 for discharging the liquid stored in the gas-liquid separation drums 72 and 82.

[0052] According to the above-described embodiment, gas-liquid separation drums 72 and 82 are provided in the first discharge lines 18A and 38A for discharging gas from the first gas-liquid separators 16A and 36A, and the flow rate of the electrolyte in the diversion lines 50 and 60 or the return lines 54 and 64 is adjusted according to the liquid level in the gas-liquid separation drums 72 and 82. That is, if the liquid level in the gas-liquid separation drums 72 and 82 rises and the risk of drain carryover to the downstream side of the first gas-liquid separators 16A and 36A increases, the flow rate of the electrolyte in the diversion lines 50 and 60 or the return lines 54 and 64 can be reduced. As a result, the flow rate of the electrolyte in the first electrolytic cell 4A decreases, and therefore the amount of electrolyte supplied from the first electrolytic cell 4A to the first gas-liquid separators 16A and 36A also decreases. Therefore, it is possible to suppress the carryover of drain to the downstream side of the first gas-liquid separators 16A and 36A, which may occur due to an increase in the flow rate of electrolyte in the first electrolytic cell 4A.

[0053] Furthermore, in the exemplary embodiment shown in Figure 4, the second ends 50b and 60b of the diversion lines 50 and 60 are connected to the second gas-liquid separators 16B and 36B. Therefore, when the second electrolytic cell 4B is stopped (i.e., hydrogen production in the second electrolytic device 2B is stopped), by operating the second circulation pumps 22B and 42B of the second electrolytic device 2B, a portion of the electrolyte flowing in the upstream portion of the first circulation line from the first circulation pump can be guided to the second circulation pumps 22B and 42B via the diversion lines 50 and 60, and then through the second gas-liquid separators 16B and 36B. In other words, a portion of the gas and electrolyte discharged from the outlet of the first electrolytic cell 4A to the first circulation lines 10A and 30A is guided to the first gas-liquid separators 16A and 36A, and the remaining portion is guided to the second gas-liquid separators 16B and 36B via the diversion lines 50 and 60. In other words, the total capacity of the gas-liquid separators is increased. Therefore, it is possible to suppress the carryover of drain to the downstream side of the first gas-liquid separators 16A and 36A, which may occur due to an increase in the flow rate of electrolyte in the first electrolytic cell 4A.

[0054] Furthermore, in the exemplary embodiments shown in Figures 1 to 5, the hydrogen production equipment 1 includes diversion lines 50, 60 and return lines 54, 64, but the amount of electrolyte flow can also be increased in a hydrogen production equipment that does not include these. In such a hydrogen production equipment, as shown in Figure 6, the cathode-side first gas-liquid separator 16A and the cathode-side second gas-liquid separator 16B include a common single cathode-side gas-liquid separator 16. Also, the anode-side first gas-liquid separator 36A and the anode-side second gas-liquid separator 36B include a common single anode-side gas-liquid separator 36. Discharge lines 18 (first discharge line 18A and second discharge line 18B) are connected to the gas-liquid separator 16. Discharge lines 38 (first discharge line 38A and second discharge line 38B) are connected to the gas-liquid separator 36. Furthermore, in the exemplary embodiment shown in Figure 6, the first circulation lines 10A, 30A include first outlet lines 12A, 32A for leading the gas and electrolyte from the first electrolytic cell 4A to the single gas-liquid separators 16, 36 described above, and first inlet lines 14A, 34A for returning the electrolyte from the single gas-liquid separators 16, 36 back to the first electrolytic cell 4A. The second circulation lines 10B, 30B include second outlet lines 12B, 32B for leading the gas and electrolyte from the second electrolytic cell 4B to the single gas-liquid separators 16, 36 described above, and second inlet lines 14B, 34B for returning the electrolyte from the single gas-liquid separators 16, 36 back to the second electrolytic cell 4B.

[0055] The first exit line 12A and the second exit line 12B have a common confluence point P1 and include a common exit line 12 downstream of the confluence point P1. The first exit line 32A and the second exit line 32B have a common confluence point P3 and include a common exit line 32 downstream of the confluence point P3. The first inlet line 14A and the second inlet line 14B have a common branching point P2 and include a common inlet line 14 upstream of the branching point P2. The first inlet line 34A and the second inlet line 34B have a common branching point P4 and include a common inlet line 34 upstream of the branching point P4.

[0056] The first circulation pump 42A and the second circulation pump 42B on the anode side may include a common single anode-side circulation pump 42. The anode-side circulation pump 42 is provided in the common inlet line 34. The first circulation pump 22A and the second circulation pump 22B on the cathode side may also include a common single cathode-side circulation pump 22. The cathode-side circulation pump 22 is provided in the common inlet line 14.

[0057] In the above-described embodiment, in a hydrogen production facility 1 including a plurality of water electrolyzers (first electrolyzer 2A and second electrolyzer 2B), a portion of the electrolyte flowing through the anode-side circulation pump 42 and the cathode-side circulation pump 22 in the common inlet lines 14 and 34 can be guided to the first electrolyzer via the first inlet lines 14A and 34A, and returned to the common outlet lines 12 and 32 via the first outlet lines 12A and 32A.

[0058] Therefore, when the second electrolytic cell 4B is stopped (i.e., hydrogen production in the second electrolytic device 2B is stopped), by operating the anode-side circulation pump 42 and the cathode-side circulation pump 22, as described above, a portion of the electrolyte flowing through the anode-side circulation pump 42 and the cathode-side circulation pump 22 in the common inlet lines 14 and 34 is guided to the first electrolytic cell via the first inlet lines 14A and 34A, and returned to the common outlet lines 12 and 32 via the first outlet lines 12A and 32A, thereby increasing the amount of electrolyte flowing in the first electrolytic cell 4A. At this time, for example, if the temperature control unit 90A controls the temperature of the electrolyte at the inlet of the first electrolytic cell 4A so that it is within a predetermined range (or a predetermined value), the average temperature of the electrolyte in the first electrolytic cell 4A will increase, thereby increasing the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell 4A. Therefore, according to the above embodiment, when the power supplied to the hydrogen production equipment 1 is low, hydrogen can be efficiently produced by effectively utilizing the electrolyte of the stopped second electrolytic cell 4B.

[0059] When the second electrolytic cell 4B is stopped, the valves 13B, 15B, 33B, and 35B provided in the second circulation lines 10B and 30B are closed, and the circulation of electrolyte in the second circulation lines 10B and 30B is stopped. On the other hand, when the second electrolytic cell 4B is in operation (when hydrogen is produced in the second electrolytic device 2B), the valves 13B, 15B, 33B, and 35B provided in the second circulation lines 10B and 30B are open, and the electrolyte circulates through the second circulation lines 10B and 30B. Also, when the first electrolytic cell 4A is in operation (when hydrogen is produced in the first electrolytic device 2A), the valves 13A, 15A, 33A, and 35A provided in the first circulation lines 10A and 30A are open, and the electrolyte circulates through the first circulation lines 10A and 30A.

[0060] The contents described in each of the above embodiments can be understood, for example, as follows:

[0061] [1] A hydrogen production apparatus (1) according to at least one embodiment of the present invention comprises a first electrolytic device (2A) and a second electrolytic device (2B), the first electrolytic device includes a first electrolytic cell (4A) for electrolyzing water, a first gas-liquid separator (16A or 36A) through which the gas produced in the first electrolytic cell is introduced, a first circulation line (10A or 30A) for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump (22A or 42A) provided in the first circulation line, the second electrolytic device includes a second electrolytic cell (4B) for electrolyzing water, a second gas-liquid separator (16B or 36B) through which the gas produced in the second electrolytic cell is introduced, a second circulation line (10B or 30B) for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump (22B or 42B) provided in the second circulation line, The system includes: a diversion line (50 or 60) for diverting at least a portion of the electrolyte flowing in the portion of the first circulation line downstream of the outlet of the first electrolytic cell and upstream of the first circulation pump to the portion of the second circulation line downstream of the outlet of the second electrolytic cell and upstream of the second circulation pump; and a return line (54 or 64) for diverting at least a portion of the electrolyte flowing in the portion of the second circulation line downstream of the second circulation pump and upstream of the inlet of the second electrolytic cell to the portion of the first circulation line downstream of the first circulation pump and upstream of the inlet of the first electrolytic cell.

[0062] In the configuration described in [1] above, since the hydrogen production facility, which includes multiple water electrolyzers (first electrolyzer and second electrolyzer), is provided with the aforementioned diversion line and return line, a portion of the electrolyte flowing upstream of the first circulation pump in the first circulation line can be guided to the second circulation pump via the diversion line and returned to the downstream portion of the first circulation pump in the first circulation line via the return line. Therefore, when the second electrolyzer is stopped (i.e., hydrogen production in the second electrolyzer is stopped), by operating the second circulation pump of the second electrolyzer, as described above, a portion of the electrolyte flowing upstream of the first circulation pump in the first circulation line is guided to the second circulation pump via the diversion line and returned to the downstream portion of the first circulation pump in the first circulation line via the return line, thus increasing the amount of electrolyte flowing in the first electrolyzer. As a result, the average temperature of the electrolyte in the first electrolyzer increases, thereby increasing the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolyzer. Therefore, according to the configuration described in [1] above, when the power supply to the hydrogen production equipment is low, hydrogen can be efficiently produced by making effective use of the auxiliary equipment (second circulation pump, etc.) of the second electrolytic cell that is stopped.

[0063] [2] In some embodiments, the configuration of [1] above, the first electrolytic device includes: a first cooler (20A or 40A) provided in the first circulation line for cooling the electrolyte flowing through the first circulation line by heat exchange with a cooling medium; and a temperature control unit (90A) configured to adjust the amount of the cooling medium supplied to the first cooler so that the temperature of the electrolyte at the outlet of the first electrolytic cell is within a predetermined range.

[0064] According to the configuration of [2] above, in the first electrolytic device, the temperature of the electrolyte at the outlet of the first electrolytic cell is maintained within a predetermined range by adjusting the amount of cooling medium supplied to the first cooler. Therefore, when the second electrolytic cell is stopped, operating the second circulation pump increases the flow rate of the electrolyte in the first electrolytic cell as described above, which raises the average temperature of the electrolyte in the first electrolytic cell. This increases the electrolysis efficiency in the first electrolytic cell. Thus, according to the configuration of [2] above, when the power supplied to the hydrogen production equipment is low, hydrogen can be efficiently produced by effectively utilizing the auxiliary equipment (second circulation pump, etc.) of the stopped second electrolytic cell.

[0065] [3] In some embodiments, in the configuration of [1] or [2] above, the diversion line has a first end (50a or 60a) connected to a portion of the first circulation line downstream of the outlet of the first electrolytic cell and upstream of the first circulation pump, and a second end (50b or 60b) connected to a portion of the second circulation line downstream of the outlet of the second electrolytic cell and upstream of the second circulation pump, and the return line has a first end (54a or 64a) connected to a portion of the second circulation line downstream of the second circulation pump and upstream of the inlet of the second electrolytic cell, and a second end (54b or 64b) connected to a portion of the first circulation line downstream of the first circulation pump and upstream of the inlet of the first electrolytic cell.

[0066] According to the configuration described in [3] above, when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), operating the second circulation pump of the second electrolytic device allows a portion of the electrolyte flowing in the upstream part of the first circulation line to be directed to the second circulation pump via a diversion line and returned to the downstream part of the first circulation line via a return line, thereby increasing the amount of electrolyte flowing in the first electrolytic cell. As a result, the average temperature of the electrolyte in the first electrolytic cell increases, thereby improving the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell. Therefore, according to the configuration described in [3] above, when the power supply to the hydrogen production equipment is low, the auxiliary equipment of the stopped second electrolytic cell (such as the second circulation pump) can be effectively utilized to efficiently produce hydrogen.

[0067] [4] In some embodiments, in the configuration of [3] above, the first end of the diversion line is connected to a portion of the first circulation line downstream of the first gas-liquid separator and upstream of the first circulation pump, and the second end of the diversion line is connected to a portion of the second circulation line downstream of the second gas-liquid separator and upstream of the second circulation pump.

[0068] According to the configuration described in [4] above, when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), operating the second circulation pump of the second electrolytic device allows a portion of the electrolyte flowing in the upstream part of the first circulation line to be directed to the second circulation pump via a diversion line and returned to the downstream part of the first circulation line via a return line, thereby increasing the amount of electrolyte flowing in the first electrolytic cell. As a result, the average temperature of the electrolyte in the first electrolytic cell increases, thereby improving the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell. Therefore, according to the configuration described in [4] above, when the power supply to the hydrogen production equipment is low, the auxiliary equipment of the stopped second electrolytic cell (such as the second circulation pump) can be effectively utilized to efficiently produce hydrogen.

[0069] [5] In some embodiments, in the configuration of [4] above, the first electrolytic device includes a first cooler (20A or 40A) provided in the first circulation line downstream of the first gas-liquid separator and upstream of the first circulation pump for cooling the electrolyte flowing through the first circulation line by heat exchange with a cooling medium; the second electrolytic device includes a second cooler (20B or 40B) provided in the second circulation line downstream of the second gas-liquid separator and upstream of the second circulation pump for cooling the electrolyte flowing through the second circulation line by heat exchange with a cooling medium; the first end of the diversion line is connected to a portion of the first circulation line downstream of the first cooler and upstream of the first circulation pump; and the second end of the diversion line is connected to a portion of the second circulation line downstream of the second cooler and upstream of the second circulation pump.

[0070] According to the configuration of [5] above, when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), by operating the second circulation pump of the second electrolytic device, a portion of the electrolyte flowing in the part of the first circulation line downstream of the first cooler and upstream of the first circulation pump is guided to the second circulation pump via a diversion line through the part of the second circulation line downstream of the second cooler (i.e., without going through the second cooler), and is returned to the part of the first circulation line downstream of the first circulation pump via a return line. As a result, the amount of electrolyte flowing in the first electrolytic cell can be increased and the average temperature of the electrolyte in the first electrolytic cell can be raised without using the second cooler in the second electrolytic device. This makes it possible to increase the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell. Therefore, according to the configuration of [5] above, when the power supply to the hydrogen production equipment is low, hydrogen can be efficiently produced by effectively utilizing the auxiliary equipment (second circulation pump, etc.) of the stopped second electrolytic cell.

[0071] [6] In some embodiments, in the configuration of [3] above, the first end of the diversion line is connected to a portion of the first circulation line downstream of the outlet of the first electrolytic cell and upstream of the first gas-liquid separator, and the second end of the diversion line is connected to a portion of the second circulation line downstream of the outlet of the second electrolytic cell and upstream of the second gas-liquid separator, or to the second gas-liquid separator.

[0072] According to the configuration described in [6] above, when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), by operating the second circulation pump of the second electrolytic device, a portion of the electrolyte flowing in the upstream portion of the first circulation line to the first circulation pump can be guided to the second circulation pump via a diversion line and through the second gas-liquid separator. In other words, a portion of the gas and electrolyte discharged from the outlet of the first electrolytic cell to the first circulation line is guided to the first gas-liquid separator, and the remaining portion is guided to the second gas-liquid separator via a diversion line. Therefore, it is possible to suppress the carryover of drain to the downstream side of the first gas-liquid separator that may occur due to an increase in the amount of electrolyte flowing in the first electrolytic cell.

[0073] [7] In some embodiments, in any of the configurations of [1] to [6] above, the hydrogen production equipment includes: a first discharge line (18A or 38A) for discharging the gas from the first gas-liquid separator; a gas-liquid separation drum (72 or 82) provided in the first discharge line; and a flow rate adjustment unit (e.g., valve 52 or 62) for adjusting the flow rate of the electrolyte in the diversion line or the return line according to the liquid level in the gas-liquid separation drum.

[0074] According to the configuration described in [7] above, a gas-liquid separation drum is provided in the first discharge line for discharging gas from the first gas-liquid separator, and the flow rate of the electrolyte in the diversion line or return line is adjusted according to the liquid level in the gas-liquid separation drum. That is, if the liquid level in the gas-liquid separation drum rises and the risk of drain carryover to the downstream side of the first gas-liquid separator increases, the flow rate of the electrolyte in the diversion line or return line can be reduced. As a result, the flow rate of the electrolyte in the first electrolytic cell decreases, and therefore the amount of electrolyte supplied from the first electrolytic cell to the first gas-liquid separator also decreases. Consequently, drain carryover to the downstream side of the first gas-liquid separator, which may occur due to an increase in the amount of electrolyte flowing in the first electrolytic cell, can be suppressed.

[0075] [8] In some embodiments, in the configuration of [1] or [2] above, the first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator (16 or 36), the first circulation line (10A, 30A) includes a first outlet line (12A, 32A) for leading the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator, and a first inlet line (14A, 34A) for returning the electrolyte from the single gas-liquid separator to the first electrolytic cell, the second circulation line (10B, 30B) includes a second outlet line (12B, 32B) for leading the gas and electrolyte from the second electrolytic cell to the single gas-liquid separator, and a second inlet line (14B, 34B) for returning the electrolyte from the single gas-liquid separator to the second electrolytic cell, The first outlet line and the second outlet line have a common confluence point (P1, P3) and include a common outlet line (12, 32) downstream of the confluence point; the first inlet line and the second inlet line have a common branching point (P2, P4) and include a common inlet line (14, 34) upstream of the branching point; the diversion line includes a portion of the second inlet line downstream of the branching point and upstream of the second circulation pump; the return line has a first end (54a, 64a) connected to a portion of the second inlet line downstream of the second circulation pump and upstream of the inlet of the second electrolytic cell, and a second end (54b, 64b) connected to a portion of the first inlet line downstream of the first circulation pump and upstream of the inlet of the first electrolytic cell.

[0076] According to the configuration described in [8] above, in a hydrogen production facility where a common gas-liquid separator is provided for multiple electrolytic cells (including at least the first and second electrolytic cells), when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), operating the second circulation pump of the second electrolytic device allows, as described above, a portion of the electrolyte flowing in the upstream part of the first circulation line to the second circulation pump via a diversion line and returned to the downstream part of the first circulation line to the first circulation pump via a return line, thereby increasing the amount of electrolyte flowing in the first electrolytic cell. As a result, the average temperature of the electrolyte in the first electrolytic cell increases, thereby improving the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell. Therefore, according to the configuration described in [8] above, when the power supply to the hydrogen production facility is low, the auxiliary equipment of the stopped second electrolytic cell (such as the second circulation pump) can be effectively utilized to efficiently produce hydrogen.

[0077] [9] A hydrogen production apparatus (1) according to at least one embodiment of the present invention comprises at least a first electrolytic device (2A) and a second electrolytic device, the first electrolytic device includes a first electrolytic cell (4A) for electrolyzing water, a first gas-liquid separator (16A or 36A) through which the gas produced in the first electrolytic cell is introduced, a first circulation line (10A or 30A) for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump (22A or 42A) provided in the first circulation line, the second electrolytic device includes a second electrolytic cell (4B) for electrolyzing water, a second gas-liquid separator (16B or 36B) through which the gas produced in the second electrolytic cell is introduced, a second circulation line (10B or 30B) for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump (22B or 42B) provided in the second circulation line, The first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator (16 or 36), the first circulation pump and the second circulation pump include a common single circulation pump (22 or 42), the first circulation line includes a first outlet line (12A, 32A) for leading the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator, and a first inlet line (14A, 34A) for returning the electrolyte from the single gas-liquid separator to the first electrolytic cell, the second circulation line includes a second outlet line (12B, 32B) for leading the gas and electrolyte from the second electrolytic cell to the single gas-liquid separator, and a second inlet line (14B, 34B) for returning the electrolyte from the single gas-liquid separator to the second electrolytic cell, The first outlet line and the second outlet line have a common confluence point (P1, P3) and include a common outlet line (12, 32) downstream of the confluence point, and the first inlet line and the second inlet line have a common branching point (P2, P4) and include a common inlet line (14, 34) upstream of the branching point, and the inlet valves (15B, 35B) of the second electrolytic cell are configured to be closed when hydrogen is being produced by the first electrolytic device while the second electrolytic cell is stopped.

[0078] In the configuration described in [9] above, when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), operating the anode-side circulation pump and the cathode-side circulation pump allows a portion of the electrolyte flowing through the anode-side and cathode-side circulation pumps in the common inlet line to be guided to the first electrolytic cell via the first inlet line and returned to the common outlet line via the first outlet line, thereby increasing the amount of electrolyte flowing through the first electrolytic cell. As a result, the average temperature of the electrolyte in the first electrolytic cell increases, thereby improving the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell. Therefore, according to the configuration described in [9] above, when the power supply to the hydrogen production equipment is low, hydrogen can be efficiently produced by effectively utilizing the electrolyte in the stopped second electrolytic cell.

[0079]

[10] A method for operating a hydrogen production facility (1) according to at least one embodiment of the present invention is a method for operating a hydrogen production facility according to any one of the above items [1] to [8], comprising the step of operating the second circulation pump (22B or 42B) while hydrogen is being produced by the first electrolytic device (2A) with the second electrolytic cell (4B) stopped, thereby circulating a portion of the electrolyte flowing through the first circulation line (10A or 30A) through the diversion line (50 or 60) and the return line (54 or 64).

[0080] In the method described in

[10] above, when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), the second circulation pump of the second electrolytic device is operated while hydrogen is being produced by the first electrolytic device. As a result, a portion of the electrolyte flowing in the upstream part of the first circulation line to the first circulation pump is guided to the second circulation pump via a diversion line and returned to the downstream part of the first circulation line to the first circulation pump via a return line, thereby increasing the amount of electrolyte flowing in the first electrolytic cell. Consequently, the average temperature of the electrolyte in the first electrolytic cell increases, thereby improving the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell. Therefore, according to the method described in [9] above, when the power supply to the hydrogen production equipment is low, hydrogen can be efficiently produced by effectively utilizing the auxiliary equipment (second circulation pump, etc.) of the stopped second electrolytic cell.

[0081]

[11] A method for operating a hydrogen production facility (1) according to at least one embodiment of the present invention, wherein the hydrogen production facility comprises at least a first electrolytic device (2A) and a second electrolytic device (2B), the first electrolytic device includes a first electrolytic cell (4A) for electrolyzing water, a first gas-liquid separator (16A or 36A) through which the gas produced in the first electrolytic cell is introduced, a first circulation line (10A or 30A) for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump (22A or 42A) provided in the first circulation line, the second electrolytic device includes a second electrolytic cell (4B) for electrolyzing water, a second gas-liquid separator (16B or 36B) through which the gas produced in the second electrolytic cell is introduced, and a second circulation line (10B or 30B) for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, The first circulation line includes a second circulation pump (22B or 42B) provided in the second circulation line, the first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator (16 or 36), the first circulation pump and the second circulation pump include a common single circulation pump (22 or 42), the first circulation line includes a first outlet line (12A, 32A) for leading the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator, and a first inlet line (14A, 34A) for returning the electrolyte from the single gas-liquid separator to the first electrolytic cell, the second circulation line includes a second outlet line (12B, 32B) for leading the gas and electrolyte from the second electrolytic cell to the single gas-liquid separator, and a second inlet line (14B, 34B) for returning the electrolyte from the single gas-liquid separator to the second electrolytic cell, The first outlet line and the second outlet line have a common confluence point (P1, P3) and include a common outlet line (12, 32) downstream of the confluence point, the first inlet line and the second inlet line have a common branching point (P2, P4) and include a common inlet line (14, 34) upstream of the branching point, and the inlet valve (15B,The procedure includes the steps of closing 35B) and operating the common single circulation pump while hydrogen is being produced by the first electrolytic device with the second electrolytic cell stopped.

[0082] In the method described in

[11] above, when the second electrolytic cell is stopped (i.e., hydrogen production in the second electrolytic device is stopped), the circulation pumps on the anode and cathode sides are activated. This allows a portion of the electrolyte flowing through the circulation pumps on the anode and cathode sides in the common inlet line to be guided to the first electrolytic cell via the first inlet line and returned to the common outlet line via the first outlet line, thereby increasing the amount of electrolyte flowing through the first electrolytic cell. As a result, the average temperature of the electrolyte in the first electrolytic cell increases, thereby improving the electrolysis efficiency (i.e., hydrogen production efficiency) in the first electrolytic cell. Therefore, according to the method described in

[11] above, when the power supply to the hydrogen production equipment is low, hydrogen can be efficiently produced by effectively utilizing the electrolyte in the stopped second electrolytic cell.

[0083] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0084] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances sufficient to achieve the same function. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" shall not only describe states of being strictly equal, but also describe states where tolerances or differences exist to the extent that the same function is achieved. Furthermore, in this specification, expressions describing shapes such as quadrilaterals or cylindrical shapes shall not only describe geometrically precise quadrilaterals or cylindrical shapes, but also describe shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect is achieved. In addition, in this specification, expressions such as "equipment," "includes," or "possesses" a component are not exclusive expressions that exclude the existence of other components.

[0085] 1 Hydrogen Production Equipment 2A First Electrolyzer 2B Second Electrolyzer 4A First Electrolyzer Cell 4B Second Electrolyzer Cell 6A, 6B Makeup Water Line 10A, 30A First Circulation Line 10B, 30B Second Circulation Line 12, 32 Common Outlet Line 12A, 32A First Outlet Line 12B, 32B Second Outlet Line 13A Outlet Valve 13B Outlet Valve 14, 34 Common Inlet Line 14A, 34A First Inlet Line 14B, 34B Second Inlet Line 15A Inlet Valve 15B Inlet Valve 16, 36 Gas-Liquid Separator 16A, 36A First Gas-Liquid Separator 16B, 36B Second Gas-Liquid Separator 33A Outlet Valve 33B Outlet Valve 35A Inlet Valve 35B Inlet Valve 52, 56, 62, 66 Valves 18, 38 Discharge lines 18A, 38A First discharge line 18B, 38B Second discharge line 20, 40 Coolers 20A, 40A First cooler 20B, 40B Second cooler 22A, 42A First circulation pump 22B, 42B Second circulation pump 50, 60 Diversion lines 50a, 60a First end 50b, 60b Second end 54, 64 Return lines 54a, 54b First end 64a, 64b Second end 70, 80 Demisters 72, 82 Gas-liquid separation drums 74, 84 Liquid level gauges 76, 86 Discharge section 90A Temperature control section 92A, 94A Cooling medium lines 93A, 95A Cooling medium valves 96A, 97A Temperature sensors P1, P3 Confluence point P2, P4 junction

Claims

1. The electrolytic apparatus comprises at least a first electrolytic apparatus and a second electrolytic apparatus, the first electrolytic apparatus includes a first electrolytic cell for electrolyzing water, a first gas-liquid separator through which the gas produced in the first electrolytic cell is introduced, a first circulation line for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump provided in the first circulation line, the second electrolytic apparatus includes a second electrolytic cell for electrolyzing water, a second gas-liquid separator through which the gas produced in the second electrolytic cell is introduced, a second circulation line for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump provided in the second circulation line, and a diversion line for diverting at least a portion of the electrolyte flowing in the portion of the first circulation line downstream of the outlet of the first electrolytic cell and upstream of the first circulation pump to the portion of the second circulation line downstream of the outlet of the second electrolytic cell and upstream of the second circulation pump, A hydrogen production facility comprising: a return line for merging at least a portion of the electrolyte flowing in the portion of the second circulation line downstream of the second circulation pump and upstream of the inlet of the second electrolytic cell with the portion of the first circulation line downstream of the first circulation pump and upstream of the inlet of the first electrolytic cell.

2. The hydrogen production apparatus according to claim 1, comprising: a first cooler provided in the first circulation line for cooling the electrolyte flowing through the first circulation line by heat exchange with a cooling medium; and a temperature control unit configured to adjust the amount of the cooling medium supplied to the first cooler so that the temperature of the electrolyte at the outlet of the first electrolytic cell is within a predetermined range.

3. The hydrogen production apparatus according to claim 1 or 2, wherein the diversion line has a first end connected to a portion of the first circulation line downstream of the outlet of the first electrolytic cell and upstream of the first circulation pump, and a second end connected to a portion of the second circulation line downstream of the outlet of the second electrolytic cell and upstream of the second circulation pump, and the return line has a first end connected to a portion of the second circulation line downstream of the second circulation pump and upstream of the inlet of the second electrolytic cell, and a second end connected to a portion of the first circulation line downstream of the first circulation pump and upstream of the inlet of the first electrolytic cell.

4. The hydrogen production apparatus according to claim 3, wherein the first end of the diversion line is connected to a portion of the first circulation line downstream of the first gas-liquid separator and upstream of the first circulation pump, and the second end of the diversion line is connected to a portion of the second circulation line downstream of the second gas-liquid separator and upstream of the second circulation pump.

5. The hydrogen production apparatus according to claim 4, wherein the first electrolytic apparatus is provided in the first circulation line downstream of the first gas-liquid separator and upstream of the first circulation pump, and includes a first cooler for cooling the electrolyte flowing through the first circulation line by heat exchange with a cooling medium; the second electrolytic apparatus is provided in the second circulation line downstream of the second gas-liquid separator and upstream of the second circulation pump, and includes a second cooler for cooling the electrolyte flowing through the second circulation line by heat exchange with a cooling medium; the first end of the diversion line is connected to a portion of the first circulation line downstream of the first cooler and upstream of the first circulation pump; and the second end of the diversion line is connected to a portion of the second circulation line downstream of the second cooler and upstream of the second circulation pump.

6. The hydrogen production apparatus according to claim 3, wherein the first end of the diversion line is connected to a portion of the first circulation line downstream of the outlet of the first electrolytic cell and upstream of the first gas-liquid separator, and the second end of the diversion line is connected to a portion of the second circulation line downstream of the outlet of the second electrolytic cell and upstream of the second gas-liquid separator, or to the second gas-liquid separator.

7. A hydrogen production apparatus according to claim 1 or 2, comprising: a first discharge line for discharging the gas from the first gas-liquid separator; a gas-liquid separation drum provided in the first discharge line; and a flow rate adjustment unit for adjusting the flow rate of the electrolyte in the diversion line or the return line according to the liquid level in the gas-liquid separation drum.

8. The first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator; the first circulation line includes a first outlet line for leading the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator; and a first inlet line for returning the electrolyte from the single gas-liquid separator to the first electrolytic cell; the second circulation line includes a second outlet line for leading the gas and electrolyte from the second electrolytic cell to the single gas-liquid separator; and a second inlet line for returning the electrolyte from the single gas-liquid separator to the second electrolytic cell; the first outlet line and the second outlet line have a common confluence point and include a common outlet line downstream of the confluence point; the first inlet line and the second inlet line have a common branching point and include a common inlet line upstream of the branching point; and the diversion line includes the portion of the second inlet line downstream of the branching point and upstream of the second circulation pump. The hydrogen production apparatus according to claim 1 or 2, wherein the return line has a first end connected to a portion of the second inlet line downstream of the second circulation pump and upstream of the inlet of the second electrolytic cell, and a second end connected to a portion of the first inlet line downstream of the first circulation pump and upstream of the inlet of the first electrolytic cell.

9. The electrolytic apparatus comprises at least a first electrolytic apparatus and a second electrolytic apparatus, the first electrolytic apparatus includes a first electrolytic cell for electrolyzing water, a first gas-liquid separator through which the gas produced in the first electrolytic cell is introduced, a first circulation line for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump provided on the first circulation line, the second electrolytic apparatus includes a second electrolytic cell for electrolyzing water, a second gas-liquid separator through which the gas produced in the second electrolytic cell is introduced, a second circulation line for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump provided on the second circulation line, the first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator, the first circulation pump and the second circulation pump include a common single circulation pump, the first circulation line includes a first outlet line for introducing the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator, A hydrogen production facility comprising: a first inlet line for returning the electrolyte from the single gas-liquid separator back to the first electrolytic cell; a second circulation line comprising: a second outlet line for guiding the gas and electrolyte from the second electrolytic cell back to the single gas-liquid separator; and a second inlet line for returning the electrolyte from the single gas-liquid separator back to the second electrolytic cell; the first outlet line and the second outlet line having a common confluence point and including a common outlet line downstream of the confluence point; and the first inlet line and the second inlet line having a common branching point and including a common inlet line upstream of the branching point; wherein the inlet valve of the second electrolytic cell is closed when hydrogen is being produced by the first electrolytic device while the second electrolytic cell is stopped.

10. A method for operating a hydrogen production facility according to claim 1 or 2, comprising the step of operating the second circulation pump while hydrogen is being produced by the first electrolytic device with the second electrolytic cell stopped, thereby circulating a portion of the electrolyte flowing through the first circulation line through the diversion line and the return line.

11. A method for operating a hydrogen production facility, wherein the hydrogen production facility comprises at least a first electrolytic device and a second electrolytic device, the first electrolytic device includes a first electrolytic cell for electrolyzing water, a first gas-liquid separator through which the gas produced in the first electrolytic cell is introduced, a first circulation line for circulating the electrolyte between the first electrolytic cell and the first gas-liquid separator, and a first circulation pump provided in the first circulation line, the second electrolytic device includes a second electrolytic cell for electrolyzing water, a second gas-liquid separator through which the gas produced in the second electrolytic cell is introduced, a second circulation line for circulating the electrolyte between the second electrolytic cell and the second gas-liquid separator, and a second circulation pump provided in the second circulation line, the first gas-liquid separator and the second gas-liquid separator include a common single gas-liquid separator, the first circulation pump and the second circulation pump include a common single circulation pump, and the first circulation line is A method for operating a hydrogen production facility, comprising: a first outlet line for leading the gas and electrolyte from the first electrolytic cell to the single gas-liquid separator; a first inlet line for returning the electrolyte from the single gas-liquid separator to the first electrolytic cell; a second circulation line for leading the gas and electrolyte from the second electrolytic cell to the single gas-liquid separator; a second inlet line for returning the electrolyte from the single gas-liquid separator to the second electrolytic cell; the first outlet line and the second outlet line having a common confluence point and including a common outlet line downstream of the confluence point; the first inlet line and the second inlet line having a common branching point and including a common inlet line upstream of the branching point; and the steps of closing the inlet valve of the second electrolytic cell; and operating the common single circulation pump while hydrogen is being produced by the first electrolytic device with the second electrolytic cell stopped.

Images