Hydrogen Production System

Abstract

To provide a hydrogen production system capable of using up hydrogen stored in a hydrogen storage part.SOLUTION: A hydrogen production system 10 includes: a hydrogen generating apparatus 11 for generating hydrogen; a compressor 12 for compressing the generated hydrogen; a first line 13 for connecting the hydrogen generating apparatus 11 and the compressor 12; a second line 14 for connecting the compressor 12 and a hydrogen utilization facility 18 using the hydrogen pressurized by the compressor 12; a hydrogen storage part 15 for storing the hydrogen pressurized by the compressor 12; a first bypass line 16 for connecting the hydrogen storage part 15 and the first line 13; and a first control valve 17 provided on the first bypass line 16 and controlling a flow of the hydrogen in the first bypass line 16.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hydrogen production system. [Background technology]

[0002] A known hydrogen production device for producing hydrogen is described in Patent Document 1. This hydrogen production device includes a steam generator that heats supplied raw water to generate steam, an electrolysis cell that receives the steam and generates hydrogen and oxygen through high-temperature steam electrolysis, a cooling unit that cools the steam that did not react in the high-temperature steam electrolysis and condenses it into water, a gas-liquid separator that separates the generated hydrogen and the condensate into gas and liquid, a hydrogen compression unit that compresses the separated hydrogen and transfers the thermal energy generated when compressing the hydrogen to the raw water, and a hydrogen storage unit that stores the compressed hydrogen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-89205 Summary of the Invention [Problem to be solved by the invention]

[0004] The hydrogen stored in the hydrogen storage unit is supplied to a hydrogen utilization facility that utilizes the hydrogen. However, if the pressure of the hydrogen stored in the hydrogen storage unit falls below the hydrogen pressure required by the hydrogen utilization facility, there is a concern that the hydrogen storage unit will no longer be able to supply hydrogen to the hydrogen utilization facility. This poses a problem that the hydrogen remaining in the hydrogen storage unit may not be used up.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a hydrogen production system that can use up all the hydrogen stored in a hydrogen storage unit. [Means for solving the problem]

[0006] One aspect of the present invention is a hydrogen generator (11) for generating hydrogen; a compressor (12) for compressing the produced hydrogen; a first line (13) connecting the hydrogen generator and the compressor; a second line (14) connecting the compressor with a hydrogen utilization facility (18) that utilizes the hydrogen pressurized by the compressor; a hydrogen storage unit (15) that stores the hydrogen pressurized by the compressor; a first bypass line (16) connecting the hydrogen storage section and the first line; a first control valve (17) provided in the first bypass line to control the flow of the hydrogen through the first bypass line; a storage pressure sensor (25) that detects the pressure of the hydrogen stored in the hydrogen storage section; a control unit (20) that controls the first control valve, The control unit receiving a signal of the stored hydrogen pressure from the storage pressure sensor, receiving a signal of the flow rate of hydrogen generated by the hydrogen generation device, and receiving signals of the required hydrogen pressure and required hydrogen flow rate required by the hydrogen utilization facility; When the produced hydrogen flow rate is smaller than the required hydrogen flow rate, the control unit opens the first control valve on condition that the stored hydrogen pressure is smaller than a threshold value based on the required hydrogen pressure, thereby allowing the hydrogen stored in the hydrogen storage unit whose stored hydrogen pressure is determined to be smaller than the threshold value to flow through the first line. In a hydrogen production system (10). [Effects of the Invention]

[0007] By opening the first control valve, hydrogen stored in the hydrogen storage unit can be circulated to the first line via the first bypass line. The hydrogen circulated to the first line is pressurized by a compressor and then circulated to the second line and supplied to the hydrogen utilization facility. This makes it possible to use up the hydrogen stored in the hydrogen storage unit even when it is difficult to supply hydrogen from the hydrogen storage unit to the second line, for example, when the pressure of the hydrogen stored in the hydrogen storage unit falls below the pressure of the hydrogen circulating through the second line.

[0008] As described above, according to the above aspect, it is possible to provide a hydrogen production device that can use up all the hydrogen stored in the hydrogen storage unit.

[0009] In addition, the symbols in parentheses in the claims and the means for solving the problems indicate the correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a block diagram showing a state in which all valves are closed in the hydrogen production system of the first embodiment. [Figure 2] 1 is a block diagram showing a state in which the hydrogen generation device is started up and the first control valve and the main control valve are opened in the hydrogen production system of the first embodiment. FIG. [Figure 3] 1 is a block diagram showing a state in which the hydrogen generation device is started up and the supply valve and the main control valve are opened in the hydrogen production system of the first embodiment. FIG. [Figure 4] 1 is a block diagram showing a state in which the hydrogen generation device is started up and the main control valve is opened in the hydrogen production system of the first embodiment. FIG. [Figure 5] 1 is a block diagram showing a state in which the hydrogen generation device is started up and the main control valve and the relief valve are opened in the hydrogen production system of the first embodiment. FIG. [Figure 6] FIG. 2 is a block diagram showing a state in which the hydrogen generation device is stopped and the first control valve and the main control valve are open in the hydrogen production system of the first embodiment. [Figure 7] FIG. 2 is a block diagram showing a state in which the hydrogen generation device is stopped and the supply valve and the main control valve are open in the hydrogen production system of the first embodiment. [Figure 8] 3 is a flowchart showing a main routine related to the overall operation of the hydrogen production system of the first embodiment. [Figure 9] 1 is a flowchart showing an ON process of the hydrogen production system of the first embodiment. [Figure 10] 1 is a flowchart showing an OFF process of the hydrogen production system of the first embodiment. [Figure 11] FIG. 10 is a block diagram showing a hydrogen production system according to a second embodiment. [Figure 12] FIG. 10 is a block diagram showing a hydrogen production system according to a third embodiment. [Figure 13] FIG. 10 is a block diagram showing a hydrogen production system according to a fourth embodiment. [Figure 14] FIG. 10 is a block diagram showing a hydrogen production system according to a fifth embodiment. [Figure 15] FIG. 13 is a block diagram showing a state in which all valves are closed in the hydrogen production system of the sixth embodiment. [Figure 16] FIG. 13 is a block diagram showing a state in which the hydrogen generation device is started up and the first control valve and the main control valve are opened in the hydrogen production system of the sixth embodiment. [Figure 17] FIG. 13 is a block diagram showing a state in which the hydrogen generation device is started up and the second control valve and the main control valve are opened in the hydrogen production system of the sixth embodiment. [Figure 18] FIG. 13 is a block diagram showing a state in which the hydrogen generation device is stopped and the first control valve and the main control valve are opened in the hydrogen production system of the sixth embodiment. [Figure 19] 13 is a flowchart showing the ON process of the hydrogen production system of the sixth embodiment. [Figure 20] 13 is a flowchart showing the OFF process of the hydrogen production system of the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment 1) A hydrogen production system 10 of a first embodiment will be described with reference to FIGS. 1 to 10. As shown in FIG. 1, the hydrogen production system 10 of this embodiment includes a hydrogen generator 11, a compressor 12, a first line 13, a second line 14, a hydrogen storage unit 15, a first bypass line 16, and a first control valve 17. The hydrogen generator 11 generates hydrogen. The compressor 12 compresses the hydrogen generated by the hydrogen generator 11. The hydrogen generator 11 and the compressor 12 are connected by the first line 13. The compressor 12 is connected by a second line 14 to a hydrogen utilization facility 18 that utilizes the hydrogen pressurized by the compressor 12. The hydrogen pressurized by the compressor 12 is stored in the hydrogen storage unit 15. The hydrogen storage unit 15 and the first line 13 are connected by the first bypass line 16. A first control valve 17 is provided in the first bypass line 16. The first control valve 17 controls the flow of hydrogen through the first bypass line 16.

[0012] 1-1. Overview of Hydrogen Production System 10 Next, an overview of the hydrogen production system 10 will be described with reference to FIG. 1. The hydrogen generator 11 of this embodiment is not particularly limited as long as it is a device that generates hydrogen. Although not shown in detail, the hydrogen generator 11 of this embodiment is an electrolysis cell that generates hydrogen and oxygen by electrolyzing water. The hydrogen generator 11 includes a cathode (not shown), an anode (not shown), and an electrolyte (not shown) disposed between the cathode and the anode. The electrolyte is not particularly limited, and any electrolyte can be appropriately selected, for example, a solid oxide electrolyte, a proton-conducting ceramic electrolysis cell, a proton exchange membrane, an alkaline water electrolyte, or the like. In this embodiment, a solid oxide electrolyte is used.

[0013] A first line 13 is connected to the hydrogen generator 11. This allows hydrogen generated by the hydrogen generator 11 to flow through the first line 13. The first line 13 is made up of a known pipe.

[0014] A cooler 19 is disposed in the first line 13. The hydrogen flowing through the first line 13 is supplied to the cooler 19 and cooled. This causes unreacted water contained in the hydrogen generated by the hydrogen generator 11 to condense. As a result, the hydrogen is dehumidified.

[0015] The hydrogen dehumidified by the cooler 19 is supplied to the compressor 12 via a first line 13. The compressor 12 pressurizes the hydrogen to a predetermined pressure. The output of the compressor 12 may be constant, or may be configured to be changed by a control unit 20, which will be described later.

[0016] A second line 14 is connected to the compressor 12. The second line 14 is configured so that hydrogen pressurized by the compressor 12 flows through the second line 14. The second line 14 is configured using a known pipe.

[0017] A purifier 21 is disposed in the second line 14. The hydrogen flowing through the second line 14 is supplied to the purifier 21. In the purifier 21, for example, unreacted water and impurity gases other than hydrogen are removed from the hydrogen by a known method such as adsorption. This increases the purity of the hydrogen.

[0018] The hydrogen whose purity has been increased by the purifier 21 is supplied to the hydrogen utilization facility 18 via the second line 14. There are no particular limitations on the hydrogen utilization facility 18. Any facility can be selected as the hydrogen utilization facility 18, such as a facility for producing chemical substances using hydrogen as a raw material, a facility for performing reduction treatment in a reducing atmosphere formed by hydrogen, or a facility for manufacturing and processing products in a reducing atmosphere formed by hydrogen.

[0019] A supply control valve 22 is disposed in the second line 14 to control the amount of hydrogen supplied to the hydrogen utilization facility 18. The amount of hydrogen supplied to the hydrogen utilization facility 18 is adjusted by adjusting the opening degree of the supply control valve 22.

[0020] A supply line 23 is arranged in the second line 14 in a region between the purifier 21 and the supply control valve 22. The supply line 23 connects the second line 14 to a hydrogen storage unit 15 in which hydrogen is stored. This allows hydrogen to flow between the second line 14 and the hydrogen storage unit 15 via the supply line 23 branching off from the second line 14. The hydrogen stored in the hydrogen storage unit 15 is supplied to the hydrogen utilization facility 18 via the second line 14. A supply valve 24 is arranged in the supply line 23 to control the amount of hydrogen flowing through the supply line 23.

[0021] The hydrogen storage unit 15 has a configuration capable of storing hydrogen. The configuration of the hydrogen storage unit 15 is not particularly limited, and any configuration can be used, such as a tank having a storage space, a container containing a hydrogen storage alloy, or a container containing a compound capable of absorbing hydrogen. The hydrogen storage unit 15 in this embodiment is a tank. The hydrogen storage unit 15 is equipped with a storage pressure sensor 25 that detects the stored hydrogen pressure, which is the pressure of hydrogen stored in the hydrogen storage unit 15.

[0022] Furthermore, a relief line 27 equipped with a relief valve 26 is provided between the second line 14 and the hydrogen storage unit 15, closer to the hydrogen utilization equipment 18 than the supply line 23, and parallel to the supply line 23. The relief valve 26 opens when a pressure greater than a predetermined operating pressure is applied, allowing hydrogen to flow from the second line 14 to the hydrogen storage unit 15. When the pressure applied to the relief valve 26 is less than the predetermined operating pressure, the relief valve 26 closes, stopping the flow of hydrogen between the second line 14 and the hydrogen storage unit 15. The value of the operating pressure is not particularly limited, and any value can be used. The operating pressure in this embodiment is 0.95 MPa.G. Even when the relief valve 26 is open, hydrogen is prevented from flowing from the hydrogen storage unit 15 to the second line 14.

[0023] A region of the first line 13 between the cooler 19 and the compressor 12 and the hydrogen storage unit 15 are connected by a first bypass line 16. Hydrogen can flow between the region of the first line 13 between the cooler 19 and the compressor 12 and the hydrogen storage unit 15 via the first bypass line 16.

[0024] A first control valve 17 is provided in the first bypass line 16. By adjusting the opening degree of this first control valve 17, the amount of hydrogen circulating between the region of the first line 13 between the cooler 19 and the compressor 12 and the hydrogen storage section 15 can be adjusted.

[0025] The first control valve 17, the supply control valve 22, the supply valve 24, and the relief valve 26 may be configured, for example, by solenoid valves.

[0026] The hydrogen production system 10 of this embodiment includes a control unit 20. The control unit 20 is composed of a known microcomputer having a processor, memory, etc., and its peripheral circuits. The control unit 20 receives a signal of the generated hydrogen flow rate, which is the flow rate of hydrogen generated by the hydrogen generation device 11, from the hydrogen generation device 11. The control unit 20 also receives a signal of the requested hydrogen flow rate, which is the flow rate of hydrogen that the hydrogen utilization device 18 requests of the hydrogen generation device 11, and a signal of the requested hydrogen pressure, which is the pressure of hydrogen that the hydrogen utilization device 18 requests of the hydrogen generation device 11. The control unit 20 also receives a signal of the stored hydrogen pressure from the storage pressure sensor 25 of the hydrogen storage unit 15.

[0027] The control unit 20 opens or closes the first control valve 17 and the supply valve 24 based on the values ​​of the produced hydrogen flow rate, the required hydrogen flow rate, the required hydrogen pressure, and the stored hydrogen pressure.

[0028] In addition, the control unit 20 is configured to open the first control valve 17, at least when the produced hydrogen flow rate is smaller than the required hydrogen flow rate, provided that the stored hydrogen pressure is smaller than a threshold value based on the required hydrogen pressure.

[0029] The threshold value is set arbitrarily based on the required hydrogen pressure. For example, if the production conditions of the hydrogen generator 11 are changed or the aperture of the first control valve 17 is changed, the flow rate and hydrogen pressure of hydrogen circulating within the hydrogen production system 10 will change. In this case, it is conceivable that a response delay will occur between the time when the production conditions of the hydrogen generator 11 are changed or the aperture of the first control valve 17 is changed and the time when hydrogen produced under the changed conditions is supplied to the hydrogen utilization equipment 18. For this reason, a threshold value that takes the above-mentioned response delay into account is set for the required hydrogen pressure. This threshold value varies depending on the response delay of the hydrogen production system 10 and the required hydrogen pressure of the hydrogen utilization equipment 18, and is therefore set individually for each hydrogen production system 10. In this embodiment, the threshold value is set to the required hydrogen pressure + 0.05 MPa.G. The required hydrogen pressure is also set to 0.55 MPa.G. Therefore, the threshold value is set to 0.6 MPa.G. However, the required hydrogen pressure is not limited to 0.55 MPa.G. Furthermore, the threshold value is not limited to the required hydrogen pressure + 0.05 MPa.G.

[0030] In addition, the first control valve 17, the supply valve 24, the relief valve 26, and the supply control valve 22 shown in black in Figure 1 are in a closed state. In the figure, when a valve is shown in white, it means that the valve is in an open state. The same applies hereinafter.

[0031] 1-2. Hydrogen production process Next, a description will be given below of an example of the hydrogen production process of the hydrogen production system 10. However, the hydrogen production process is not limited to the following description.

[0032] 1-2-1. Start-up of hydrogen production system 10 When the hydrogen production system 10 is stopped, the first control valve 17, the supply valve 24, and the supply control valve 22 provided in the hydrogen production system 10 are closed as shown in Figure 1. When the hydrogen production system 10 is stopped, no pressure is applied to the relief valve 26, so the relief valve 26 is closed.

[0033] 8 shows a flowchart of the main routine of the hydrogen production process according to this embodiment. When the control unit 20 receives a command to start operation while the hydrogen production system 10 is stopped, it starts up the hydrogen production system 10. The control unit 20 executes an initial process (S1). That is, the control unit 20 starts up the cooler 19, the compressor 12, and the purifier 21, and then opens the supply control valve 22.

[0034] Next, the control unit 20 receives signals of various hydrogen pressures and hydrogen flow rates (S2). That is, the control unit 20 receives a signal of the generated hydrogen flow rate from the hydrogen generation device 11, receives signals of the required hydrogen pressure and required hydrogen flow rate from the hydrogen utilization equipment 18, and receives a signal of the stored hydrogen pressure from the hydrogen storage unit 15.

[0035] 1-2-2. ON processing The control unit 20 determines whether the stored hydrogen pressure is lower than a predetermined pressure (S3). In this embodiment, the predetermined pressure is set to 0.3 MPa.G. However, the predetermined pressure is not limited to 0.3 MPa.G. When the control unit 20 determines that the stored hydrogen pressure is lower than 0.3 MPa.G (S3: Y), it starts up the hydrogen generator 11 (S5). This causes hydrogen to be generated by the hydrogen generator 11. Next, the control unit 20 causes the hydrogen production system 10 to execute ON processing (S5). The ON processing is a processing that is executed when the hydrogen generator 11 is activated.

[0036] 9 shows a flowchart of the ON process. The control unit 20 determines whether the produced hydrogen flow rate is smaller than the required hydrogen flow rate (S21). When the control unit 20 determines that the produced hydrogen flow rate is smaller than the required hydrogen flow rate (S21: Y), it determines whether the stored hydrogen pressure is smaller than 0.6 MPa.G (S22). When the control unit 20 determines that the stored hydrogen pressure is smaller than 0.6 MPa.G (S22: Y), it opens the first control valve 17 (S23). Furthermore, the control unit 20 closes the supply valve 24 (S24).

[0037] In FIG. 2 , the first control valve 17 and the supply control valve 22 are shown in white. That is, the first control valve 17 and the supply control valve 22 are in an open state. On the other hand, the supply valve 24 and the relief valve 26 are shown in black, meaning that the supply valve 24 and the relief valve 26 are in a closed state. In this state, hydrogen generated in the hydrogen generator 11 flows through the hydrogen generator 11, the cooler 19, the compressor 12, the purifier 21, the supply control valve 22, and the hydrogen utilization equipment 18, as indicated by arrow A. Furthermore, hydrogen stored in the hydrogen storage unit 15 passes through the hydrogen storage unit 15, the first bypass line 16, and the first control valve 17, as indicated by arrow B, before joining the first line 13 and flowing to the compressor 12, the purifier 21, the supply control valve 22, and the hydrogen utilization equipment 18. The hydrogen supplied to the hydrogen utilization equipment 18 is indicated by arrow E. The hydrogen utilization facility 18 is supplied with hydrogen from the hydrogen generator 11 indicated by arrow A and hydrogen from the hydrogen storage unit 15 indicated by arrow B in a combined state.

[0038] 9, when the control unit 20 determines in S22 that the stored hydrogen pressure is not lower than 0.6 MPa.G (S22: N), the control unit 20 closes the first control valve 17 (S26). Furthermore, the control unit 20 opens the supply valve 24 (S27).

[0039] In FIG. 3 , the supply valve 24 and the supply control valve 22 are shown in white. That is, the supply valve 24 and the supply control valve 22 are in an open state. On the other hand, the first control valve 17 and the relief valve 26 are shown in black, meaning that the first control valve 17 and the relief valve 26 are in a closed state. In this state, hydrogen generated in the hydrogen generator 11 flows to the hydrogen generator 11, the cooler 19, the compressor 12, the purifier 21, the supply control valve 22, and the hydrogen utilization equipment 18, as indicated by arrow A. Furthermore, hydrogen stored in the hydrogen storage unit 15 passes through the supply valve 24, merges with the second line 14, and flows to the supply control valve 22 and the hydrogen utilization equipment 18, as indicated by arrow C. The hydrogen from the hydrogen generator 11, as indicated by arrow A, and the hydrogen from the hydrogen storage unit 15, as indicated by arrow C, are supplied to the hydrogen utilization equipment 18 in a merged state.

[0040] 9, when the control unit 20 determines in S21 that the produced hydrogen pressure is not lower than the required hydrogen pressure (S21: N), it closes the first control valve 17 (S28). The control valve also closes the supply valve 24 (S29). Note that when the control unit 20 executes S28, it does not determine whether the stored hydrogen pressure is lower than 0.6 MPa. Therefore, even when the stored hydrogen pressure is lower than 0.6 MPa.G, the first control valve 17 may be closed.

[0041] When S28 and S29 are executed by the control unit 20, the flow rate of the produced hydrogen is not smaller than the required hydrogen flow rate (S21:N). In other words, the flow rate of the produced hydrogen is equal to or greater than the required hydrogen flow rate. In this state, the hydrogen generator 11 is generating a larger amount of hydrogen than the hydrogen utilization facility 18 requires. Therefore, the pressure of the hydrogen circulating in the second line 14 may become 0.95 MPa.G or higher. When the pressure applied to the relief valve 26 is lower than 0.95 MPa.G, the relief valve 26 is closed. On the other hand, when the pressure applied to the relief valve 26 is equal to or greater than 0.95 MPa.G, the relief valve 26 is open.

[0042] When S28 and S29 are executed for the first time after the hydrogen production system 10 is started, it is determined in S3 that the stored hydrogen pressure is less than 0.3 MPa.G (S3: Y). Therefore, when S28 and S29 are executed for the first time after the hydrogen production system 10 is started and the relief valve 26 is opened, hydrogen flows from the second line 14 into the hydrogen storage unit 15 and is stored in the hydrogen storage unit 15.

[0043] When S28 and S29 are executed for the second or subsequent time after the hydrogen production system 10 is started, it is determined in S6, which will be described later, that the stored hydrogen pressure is not 0.98 MPa.G or higher (S6: N). Therefore, even if S28 and S29 are executed for the second or subsequent time after the hydrogen production system 10 is started and the relief valve 26 is opened, hydrogen will flow from the second line 14 into the hydrogen storage unit 15 and be stored in the hydrogen storage unit 15.

[0044] Fig. 4 shows the case where the relief valve 26 is in a closed state. In Fig. 4, the supply control valve 22 is shown in white. That is, the supply control valve 22 is in an open state. On the other hand, the first control valve 17, the supply valve 24, and the relief valve 26 are shown in black, and the first control valve 17, the supply valve 24, and the relief valve 26 are in a closed state. In this state, hydrogen generated in the hydrogen generator 11 flows through the hydrogen generator 11, the cooler 19, the compressor 12, the purifier 21, the supply control valve 22, and the hydrogen utilization equipment 18, as indicated by arrow A. Hydrogen is supplied to the hydrogen utilization equipment 18 from the hydrogen generator 11, as indicated by arrow A.

[0045] FIG. 5 shows the case where the relief valve 26 is in an open state. In FIG. 5, the relief valve 26 and the supply control valve 22 are shown in white. That is, the relief valve 26 and the supply control valve 22 are in an open state. On the other hand, the first control valve 17 and the supply valve 24 are shown in black, and the first control valve 17 and the supply valve 24 are in a closed state. In this state, hydrogen generated in the hydrogen generator 11 flows through the hydrogen generator 11, the cooler 19, the compressor 12, the purifier 21, the supply control valve 22, and the hydrogen utilization equipment 18, as indicated by arrow A, and also passes through the relief valve 26 and is stored in the hydrogen storage unit 15, as indicated by arrow D. The hydrogen utilization equipment 18 is supplied with hydrogen obtained by subtracting the amount of hydrogen stored in the hydrogen storage unit 15, as indicated by arrow D, from the hydrogen from the hydrogen generator 11, as indicated by arrow A.

[0046] 9, when S24, S27, or S29 is completed, the control unit 20 acquires various hydrogen pressure and hydrogen flow rate signals (S25). That is, the control unit 20 receives a signal of the generated hydrogen flow rate from the hydrogen generation device 11, receives signals of the required hydrogen pressure and required hydrogen flow rate from the hydrogen utilization equipment 18, and receives a signal of the stored hydrogen pressure from the hydrogen storage unit 15. The ON process ends in S25, and the process proceeds to the next step.

[0047] Returning to FIG. 8, the control unit 20 determines whether the stored hydrogen pressure is 0.98 MPa.G or higher (S6).

[0048] When the control unit 20 determines that the stored hydrogen pressure is 0.98 MPa.G or higher (S6: Y), it stops the hydrogen generator 11 (S11). Subsequently, the control unit 20 executes an OFF process (S9) described later.

[0049] On the other hand, if the produced hydrogen flow rate is not greater than the required hydrogen flow rate or the stored hydrogen pressure is less than 0.95 MPa.G (S6: N), the control unit 20 repeats the processes of S5 to S7 until it receives a termination command to stop the hydrogen production system 10 (S7). When the termination command is received (S7: Y), the control unit 20 executes a finalization process (S8). That is, the control unit 20 stops the hydrogen generator 11, the cooler 19, the compressor 12, and the purifier 21. The control unit 20 also closes the first control valve 17, the supply valve 24, and the supply control valve 22. As a result, the hydrogen production system 10 ends operation.

[0050] 1-2-3.OFF processing 8, when the control unit 20 determines that the stored hydrogen pressure is not lower than 0.3 MPa.G (S3: N), it causes the hydrogen production system 10 to execute OFF processing. The OFF processing is a processing that is executed when the hydrogen generation device 11 is stopped.

[0051] 10 shows a flowchart of the OFF process. The control unit 20 determines whether the stored hydrogen pressure is less than 0.6 MPa.G (S31). When the control unit 20 determines that the stored hydrogen pressure is less than 0.6 MPa.G (S31: Y), it opens the first control valve 17 (S32). Furthermore, the control unit 20 closes the supply valve 24 (S33).

[0052] In Figure 6, the first control valve 17 and the supply control valve 22 are shown in white. That is, the first control valve 17 and the supply control valve 22 are in an open state. On the other hand, the supply valve 24 and the relief valve 26 are shown in black, meaning that the supply valve 24 and the relief valve 26 are in a closed state. In this state, hydrogen stored in the hydrogen storage unit 15 passes through the hydrogen storage unit 15, the first bypass line 16, and the first control valve 17, as indicated by arrow B, to merge with the first line 13, and then flows to the compressor 12, the purifier 21, the supply control valve 22, and the hydrogen utilization equipment 18. The hydrogen supplied to the hydrogen utilization equipment 18 is indicated by arrow E. Hydrogen is supplied to the hydrogen utilization equipment 18 from the hydrogen storage unit 15, as indicated by arrow B.

[0053] 10, when the control unit 20 determines that the stored hydrogen pressure is not lower than 0.6 MPa.G (S31: N), the control unit 20 closes the first control valve 17 (S34). Furthermore, the control unit 20 opens the supply valve 24 (S35).

[0054] 7, the supply valve 24 and the supply control valve 22 are shown in white. That is, the supply valve 24 and the supply control valve 22 are in an open state. On the other hand, the first control valve 17 and the relief valve 26 are shown in black, and the first control valve 17 and the relief valve 26 are in a closed state. In this state, hydrogen stored in the hydrogen storage unit 15 passes through the supply valve 24, merges with the second line 14, and flows to the supply control valve 22 and the hydrogen utilization equipment 18, as indicated by arrow C. Hydrogen is supplied to the hydrogen utilization equipment 18 from the hydrogen storage unit 15, as indicated by arrow C.

[0055] Returning to FIG. 10, when S33 or S35 is completed, the OFF process is completed and the process moves to the next step.

[0056] 8, when the OFF process is completed (S9), the control unit 20 repeats the process from S2 onwards (S10: N) until it receives a termination command to stop the hydrogen production system 10. When the control unit 20 receives the termination command (S10: Y), it executes the finalization process (S8). This causes the hydrogen production system 10 to end operation.

[0057] 2-4. Operation of the hydrogen generator 11 and valves Table 1 summarizes the conditions under which the control unit 20 determines whether to start the hydrogen generator 11 in a stopped state and the conditions under which the control unit 20 determines whether to stop the hydrogen generator 11 in an operating state.

[0058] [Table 1]

[0059] As shown in Table 1, when the hydrogen generator 11 is in a stopped state, if the stored hydrogen pressure is lower than 0.3 MPa.G (S3:Y), the hydrogen generator 11 is started (S4). The value of 0.3 MPa.G takes into consideration the response delay from when the hydrogen generator 11 is started until the stored hydrogen pressure in the hydrogen storage unit 15 reaches 0 MPa.G before hydrogen is supplied to the hydrogen utilization equipment 18. The value of the stored hydrogen pressure determined in S3 is not particularly limited, and any value can be adopted depending on the hydrogen production system 10.

[0060] When the hydrogen generator 11 is in an operating state and the stored hydrogen pressure is 0.98 MPa.G or higher, the hydrogen generator 11 is stopped (S6). The value of 0.98 MPa.G is a value based on the upper limit pressure set in the hydrogen storage unit 15 of this embodiment. The upper limit pressure of the hydrogen storage unit 15 and the value based on this upper limit pressure are not particularly limited and are set individually according to the hydrogen production system 10.

[0061] Next, Table 2 summarizes the conditions under which the control unit 20 opens or closes the first control valve 17 and the supply valve 24.

[0062] [Table 2]

[0063] As shown in Table 2, when the ON process is being executed, the control unit 20 closes the first control valve 17 (S26) and opens the supply valve 24 (S27) when the produced hydrogen flow rate is smaller than the required hydrogen flow rate (S21: Y) and when the stored hydrogen pressure is not smaller than 0.6 MPa.G (S22: N).

[0064] Also, when the ON processing is being executed, if the produced hydrogen flow rate is smaller than the required hydrogen flow rate (S21: Y) and the stored hydrogen pressure is smaller than 0.6 MPa.G (S22: Y), the control unit 20 opens the first control valve 17 (S23) and closes the supply valve 24 (S24).

[0065] Furthermore, when the ON process is being executed, if the produced hydrogen flow rate is not smaller than the required hydrogen flow rate (S21: N), the control unit 20 closes the first control valve 17 (S28) and closes the supply valve 24 (S29). When a pressure of 0.95 MPa.G or more is not applied to the relief valve 26, the relief valve 26 is in a closed state, and when a pressure of 0.95 MPa.G or more is applied to the relief valve 26, the relief valve 26 is in an open state.

[0066] Also, as shown in Table 2, when the OFF processing is being executed, the control unit 20 closes the first control valve 17 (S34) and opens the supply valve 24 (S35) when the stored hydrogen pressure is not less than 0.6 MPa.G (S31:N).

[0067] Furthermore, when the OFF process is being executed, if the stored hydrogen pressure is lower than 0.6 MPa.G (S31: Y), the control unit 20 opens the first control valve 17 (S32) and closes the supply valve 24 (S33). Since the predetermined pressure is not being applied to the relief valve 26, it is in the closed state.

[0068] 1-3.Effects Next, the effects of this embodiment will be described below. According to this embodiment, by opening first control valve 17, hydrogen stored in hydrogen storage unit 15 can be circulated to first line 13 via first bypass line 16. The hydrogen circulated to first line 13 is pressurized by compressor 12 and then circulated to second line 14 and supplied to hydrogen utilization equipment 18. As a result, even if it is difficult to supply hydrogen from hydrogen storage unit 15 to second line 14, such as when the pressure of hydrogen stored in hydrogen storage unit 15 falls below the pressure of hydrogen circulating through second line 14, the hydrogen stored in hydrogen storage unit 15 can be used up.

[0069] The hydrogen production system 10 according to this embodiment further includes a storage pressure sensor 25 that detects the stored hydrogen pressure of hydrogen stored in the hydrogen storage unit 15, and a control unit 20 that controls the first control valve 17. The control unit 20 receives a signal of the stored hydrogen pressure from the storage pressure sensor 25, a signal of the flow rate of hydrogen produced by the hydrogen generation device 11, and a signal of the requested hydrogen flow rate requested by the hydrogen utilization equipment 18. The control unit 20 opens the first control valve 17 at least when the flow rate of produced hydrogen is smaller than the requested hydrogen flow rate, provided that the stored hydrogen pressure is smaller than a threshold value based on the requested hydrogen pressure.

[0070] For example, if the production conditions of the hydrogen generator 11 are changed or the aperture of the first control valve 17 is changed, the flow rate of hydrogen circulating within the hydrogen production system 10, the hydrogen pressure, etc. will change. In this case, it is conceivable that a response delay will occur between the time when the production conditions of the hydrogen generator 11 are changed or the aperture of the first control valve 17 is changed and the time when hydrogen produced under the changed conditions is supplied to the hydrogen utilization facility 18. For this reason, a threshold value that takes the above-mentioned response delay into account is set for the required hydrogen pressure, and the production conditions, etc. of the hydrogen production system 10 are changed based on this threshold value. This threshold value varies depending on the response delay of the hydrogen production system 10 and the required hydrogen pressure of the hydrogen utilization facility 18, and is therefore set individually for each hydrogen production system 10.

[0071] According to this embodiment, even if the stored hydrogen pressure is lower than the threshold value based on the required hydrogen pressure, the hydrogen stored in the hydrogen storage unit 15 can be supplied to the hydrogen utilization facility 18 by circulating it in the order of the first bypass line 16, the first control valve 17, the first line 13, the compressor 12, and the second line 14. This makes it possible to easily use up the hydrogen stored in the hydrogen storage unit 15. The threshold value is set arbitrarily based on the required hydrogen pressure required by the hydrogen utilization facility 18.

[0072] In this embodiment, the hydrogen storage unit 15 and the second line 14 are connected by a supply line 23. The supply line 23 is provided with at least one valve that controls the flow of hydrogen between the hydrogen storage unit 15 and the second line 14. In this embodiment, a supply valve 24 and a relief valve 26 are provided between the hydrogen storage unit 15 and the second line 14. These valves make it possible to control the flow of hydrogen between the second line 14 and the hydrogen storage unit 15.

[0073] The relief valve 26 is configured to allow hydrogen to flow from the second line 14 to the hydrogen storage section 15 when the pressure in the second line 14 exceeds a predetermined pressure, and to prohibit hydrogen from flowing from the hydrogen storage section 15 to the second line 14.

[0074] When the amount of hydrogen generated by the hydrogen generation device 11 is greater than the amount of hydrogen required by the hydrogen utilization equipment 18, hydrogen can be supplied to the hydrogen utilization equipment 18 while the excess hydrogen for the hydrogen utilization equipment 18 can be stored in the hydrogen storage section 15.

[0075] As described above, according to the hydrogen production system 10 of this embodiment, the hydrogen stored in the hydrogen storage unit 15 can be used up.

[0076] (Embodiment 2) Next, a hydrogen production system 30 according to a second embodiment will be described with reference to Fig. 11. In this embodiment, a buffer 31 having an inner diameter larger than that of the other portions of the second line 14 is provided in a portion of the second line 14 where the supply valve 24 and the relief valve 26 are provided. The buffer 31 may be a tank having a smaller capacity than the hydrogen storage unit 15, or may be a pipe having an inner diameter larger than that of the pipes constituting the second line 14, and can be selected appropriately as needed.

[0077] Note that, among the symbols used in the second and subsequent embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as those in the previous embodiments, unless otherwise specified.

[0078] In the hydrogen production system 30, when a process is performed on a specific device that constitutes the hydrogen production system 30, there is a time delay before the effect of this process reaches other devices. For example, when the hydrogen generator 11 is stopped after producing excessive hydrogen, it takes time for the pressure of the hydrogen circulating in the first line 13 and the second line 14 to decrease, and further for the pressure of the hydrogen supplied to the hydrogen utilization facility 18 to decrease. Similarly, when various valves provided in the hydrogen production system 30 are opened or closed, there is a time delay before the pressure in the first line 13 or the second line 14 in which the valve is provided changes to the desired pressure.

[0079] In this embodiment, a buffer 31 is provided in the second line 14. As a result, when processing is performed in the hydrogen production system 30, the buffer 31 can alleviate the response delay of pressure fluctuations in the hydrogen circulating in the second line 14. In particular, the supply valve 24 and the relief valve 26 are provided between the second line 14 and the hydrogen storage unit 15, and the response delay of pressure fluctuations when these valves are opened and closed can be effectively alleviated. Furthermore, when the first control valve 17 connecting the hydrogen storage unit 15 and the first line 13 is opened or closed, the stored hydrogen pressure of the hydrogen stored in the hydrogen storage unit 15 also fluctuates greatly. The buffer 31 can also alleviate this response delay of the stored hydrogen pressure, which is particularly effective.

[0080] The buffer 31 can be configured by a tank capable of storing hydrogen or a pipe having an inner diameter larger than that of the second line 14. The buffer 31 can be formed with such a simple configuration.

[0081] (Embodiment 3) Next, a hydrogen production system 40 according to a third embodiment will be described with reference to FIG. 12 . This embodiment is a modified example of the second embodiment. In this embodiment, the supply line 23 is connected between the buffer 41 and the supply control valve 22. As a result, in this embodiment, the buffer 41 is not interposed between the supply valve 24 and the hydrogen utilization equipment 18. As a result, it is possible to reduce the response delay in the hydrogen utilization equipment 18 when the supply valve 24 is opened or closed. In addition, a check valve 42 is disposed between the buffer 41 and the connection portion between the supply line 23 and the second line 14. This allows hydrogen to flow from the buffer 41 to the hydrogen utilization equipment 18, while preventing hydrogen from flowing back from the hydrogen storage unit 15 to the buffer 41.

[0082] (Embodiment 4) Next, a hydrogen production system 50 according to a fourth embodiment will be described with reference to Fig. 13. In this embodiment, the first bypass line 16 is connected to a first hydrogen storage unit 51 capable of storing hydrogen therein. The first hydrogen storage unit 51 is connected to a second hydrogen storage unit 52 capable of storing hydrogen therein via a connecting line 53. The hydrogen stored in the first hydrogen storage unit 51 and the hydrogen stored in the second hydrogen storage unit 52 can flow between them via the connecting line 53. The connecting line 53 is formed of a known pipe. A valve may be provided in the connecting line 53.

[0083] The second hydrogen storage section 52 is connected to the second line 14 by a supply line 23 and a relief line 27 .

[0084] The volume of first hydrogen storage section 51 and the volume of second hydrogen storage section 52 may be the same or different. In this embodiment, an example is shown in which the volume of first hydrogen storage section 51 is larger than the volume of second hydrogen storage section 52. Note that the volume of first hydrogen storage section 51 may be smaller than the volume of second hydrogen storage section 52.

[0085] A storage pressure sensor 25 is disposed in first hydrogen storage section 51. However, storage pressure sensor 25 may be disposed in both first hydrogen storage section 51 and second hydrogen storage section 62, or may be disposed in second hydrogen storage section 52.

[0086] Although the hydrogen production system 50 according to this embodiment is configured to include the first hydrogen storage unit 51 and the second hydrogen storage unit 52, the present invention is not limited to this and may be configured to include three or more hydrogen storage units.

[0087] According to this embodiment, hydrogen can be divided and stored in the first hydrogen storage unit 51 and the second hydrogen storage unit 52. This reduces the manufacturing cost of the hydrogen production system 50 compared to when hydrogen is stored in one large hydrogen storage unit.

[0088] (Embodiment 5) Next, a hydrogen production system 60 according to a fifth embodiment will be described with reference to Fig. 14. This embodiment differs from the fourth embodiment in that a buffer 61 having an inner diameter larger than that of the other portions of the second line 14 is provided in a portion of the second line 14 where the supply valve 24 and the relief valve 26 are provided.

[0089] According to this embodiment, when the first control valve 17 or the supply valve 24 is opened or closed, the response delay caused by the provision of the first hydrogen storage section 51 and the second hydrogen storage section 52 can be effectively alleviated by the buffer 61.

[0090] (Embodiment 6) 6-1. Overview of Hydrogen Production System 70 Next, a hydrogen production system 70 of a sixth embodiment will be described with reference to Fig. 15 to Fig. 20. As shown in Fig. 15, in this embodiment, a second bypass line 71 is provided that connects a portion of the second line 14 between the compressor 12 and the purifier 21 with the hydrogen storage unit 15. The second bypass line 71 allows hydrogen circulating through the second line 14 to be supplied to the hydrogen storage unit 15 from the region between the compressor 12 and the purifier 21.

[0091] The second bypass line 71 is provided with a second control valve 72. The amount of hydrogen flowing through the second bypass line 71 can be controlled by adjusting the aperture of the second control valve 72. The control unit 20 is configured to adjust the aperture of the second control valve 72 based on the produced hydrogen flow rate, the required hydrogen pressure, the required hydrogen flow rate, and the stored hydrogen pressure. The second control valve 72 can be configured with, for example, a solenoid valve.

[0092] A buffer 73 is provided in the second line 14. The inner diameter of the buffer 73 is set to be larger than the inner diameter of the portion of the second line 14 that is different from the buffer 73. The buffer 73 and the hydrogen storage unit 15 are connected by a relief line 27. A relief valve 26 is provided in the relief line 27.

[0093] In the hydrogen production system 70 according to this embodiment, the supply line 23 and the supply valve 24 are not provided between the hydrogen storage unit 15 and the buffer 73 .

[0094] In FIG. 15, the first control valve 17, the second control valve 72, the relief valve 26 and the supply control valve 22 are painted black and are in a closed state.

[0095] The configuration other than the above is substantially the same as that of the first embodiment, so the same members are given the same reference numerals and redundant explanations will be omitted.

[0096] 6-2. Hydrogen production process Next, a description will be given below of an example of the hydrogen production process of the hydrogen production system 70. However, the hydrogen production process is not limited to the following description.

[0097] When the hydrogen production system 70 is stopped, the first control valve 17, the supply valve 24, and the supply control valve 22 provided in the hydrogen production system 70 are closed, as shown in Figure 15. When the hydrogen production system 70 is stopped, no pressure is applied to the relief valve 26, so the relief valve 26 is closed.

[0098] In the hydrogen production process of the hydrogen production system 70 of this embodiment, the details of the ON process and the OFF process are different from those of embodiment 1. The main routine of the hydrogen production process is the same as in embodiment 1, so a duplicated explanation will be omitted.

[0099] 6-2-1. ON processing 19 shows a flowchart of the ON process. The control unit 20 determines whether the produced hydrogen flow rate is smaller than the required hydrogen flow rate (S41). When the control unit 20 determines that the produced hydrogen flow rate is smaller than the required hydrogen flow rate (S41: Y), it opens the first control valve 17 (S42). Furthermore, the control unit 20 closes the second control valve 72 (S43).

[0100] In FIG. 16 , the first control valve 17 and the supply control valve 22 are shown in white. That is, the first control valve 17 and the supply control valve 22 are in an open state. On the other hand, the second control valve 72 and the relief valve 26 are shown in black, meaning that the second control valve 72 and the relief valve 26 are in a closed state. In this state, hydrogen generated in the hydrogen generator 11 flows through the hydrogen generator 11, the cooler 19, the compressor 12, the purifier 21, the buffer 73, the supply control valve 22, and the hydrogen utilization equipment 18, as indicated by arrow A. Furthermore, hydrogen stored in the hydrogen storage unit 15 passes through the hydrogen storage unit 15, the first bypass line 16, and the first control valve 17, as indicated by arrow B, before joining the first line 13 and flowing to the compressor 12, the purifier 21, the buffer 73, the supply control valve 22, and the hydrogen utilization equipment 18. The hydrogen supplied to the hydrogen utilization equipment 18 is indicated by arrow E. The hydrogen utilization facility 18 is supplied with hydrogen from the hydrogen generator 11 indicated by arrow A and hydrogen from the hydrogen storage unit 15 indicated by arrow B in a combined state.

[0101] 19, when the control unit 20 determines in S41 that the produced hydrogen pressure is not lower than the required hydrogen pressure (S41: N), the control unit 20 closes the first control valve 17 (S45). Furthermore, the control unit 20 opens the second control valve 72 (S46).

[0102] When S45 and S46 are executed by the control unit 20, the flow rate of the produced hydrogen is not smaller than the required hydrogen flow rate (S41:N). In other words, the flow rate of the produced hydrogen is equal to or greater than the required hydrogen flow rate. In this state, the hydrogen generator 11 is producing a larger amount of hydrogen than the hydrogen utilization facility 18 requires. Therefore, the pressure of the hydrogen circulating in the second line 14 may become 0.95 MPa.G or higher. When the pressure applied to the relief valve 26 is lower than 0.95 MPa.G, the relief valve 26 is closed. On the other hand, when the pressure applied to the relief valve 26 is equal to or greater than 0.95 MPa.G, the relief valve 26 is open.

[0103] When S45 and S46 are executed for the first time after the hydrogen production system 70 is started, it is determined in S3 that the stored hydrogen pressure is less than 0.3 MPa.G (FIG. 8, S3: Y). Therefore, when S45 and S46 are executed for the first time after the hydrogen production system 70 is started and the relief valve 26 is opened, hydrogen flows from the buffer 73 into the hydrogen storage unit 15 and is stored in the hydrogen storage unit 15.

[0104] In Figure 17, the second control valve 72 and the supply control valve 22 are shown in white. That is, the second control valve 72 and the supply control valve 22 are in an open state. On the other hand, the first control valve 17 and the relief valve 26 are shown in black, and the first control valve 17 and the relief valve 26 are in a closed state. In this state, hydrogen generated in the hydrogen generator 11 flows through the hydrogen generator 11, the cooler 19, the compressor 12, the purifier 21, the buffer 83, the supply control valve 22, and the hydrogen utilization equipment 18, as indicated by arrow A. The hydrogen also flows from the second line 14 through the second control valve 72 and is stored in the hydrogen storage unit 15. The hydrogen utilization equipment 18 is supplied with hydrogen obtained by subtracting the hydrogen stored in the hydrogen storage unit 15, as indicated by arrow F, from the hydrogen generated by the hydrogen generator 11, as indicated by arrow A.

[0105] 19, when S43 or S46 is completed, the control unit 20 acquires various hydrogen pressure and hydrogen flow rate signals (S44). That is, the control unit 20 receives a signal of the generated hydrogen flow rate from the hydrogen generation device 11, receives signals of the required hydrogen pressure and required hydrogen flow rate from the hydrogen utilization equipment 18, and receives a signal of the stored hydrogen pressure from the hydrogen storage unit 15. The ON process ends in S44, and the process moves to the next step. The control unit 20 executes the process from S6 onwards in FIG. 8.

[0106] 6-2-2.OFF processing A flowchart of the OFF process is shown in Figure 20. The control unit 20 opens the first control valve 17 (S47). Furthermore, the control unit 20 closes the second control valve 72 (S48).

[0107] In Figure 18, the first control valve 17 and the supply control valve 22 are shown in white. That is, the first control valve 17 and the supply control valve 22 are in the open state. On the other hand, the second control valve 82 and the relief valve 26 are shown in black, meaning that the second control valve 72 and the relief valve 26 are in the closed state. In this state, hydrogen stored in the hydrogen storage unit 15 passes through the hydrogen storage unit 15, the first bypass line 16, and the first control valve 17, as indicated by arrow B, to merge with the first line 13, and then flows to the compressor 12, the purifier 21, the buffer 83, the supply control valve 22, and the hydrogen utilization equipment 18. The hydrogen supplied to the hydrogen utilization equipment 18 is indicated by arrow E. Hydrogen is supplied to the hydrogen utilization equipment 18 from the hydrogen storage unit 15, as indicated by arrow B.

[0108] 20, when S48 is completed, the OFF process is completed and the process moves to the next step. The control unit 20 executes the process from S10 onward in FIG.

[0109] 6-3. Operation of the hydrogen generator 11 and valves Table 3 shows the conditions under which the control unit 20 determines whether the first control valve 17 and the supply valve 24 are opened or closed.

[0110] [Table 3]

[0111] As shown in Table 3, when the ON process is being executed, if the produced hydrogen flow rate is smaller than the required hydrogen flow rate (S41: Y), the control unit 20 closes the first control valve 17 (S42) and opens the supply valve 24 (S43).

[0112] Furthermore, when the ON process is being executed, if the produced hydrogen flow rate is not smaller than the required hydrogen flow rate (S41: N), the control unit 20 closes the first control valve 17 (S45) and closes the supply valve 24 (S46).

[0113] Furthermore, as shown in Table 3, when the OFF process is being executed, the first control valve 17 is closed (S47) and the supply valve 24 is opened (S48).

[0114] The conditions for determining whether the control unit 20 should start the hydrogen generator 11 in a stopped state and the conditions for determining whether the control unit 20 should stop the hydrogen generator 11 in an operating state are the same as those in embodiment 1, so redundant explanations will be omitted.

[0115] Effects Next, the effects of this embodiment will be described. According to this embodiment, a purifier 21 that removes impurities from hydrogen is disposed in the second line 14 between the compressor 12 and the hydrogen storage unit 15. A second bypass line 71 connects the portion of the second line 14 between the compressor 12 and the purifier 21 to the hydrogen storage unit 15. The second bypass line 71 is disposed so as to bypass the purifier 21. The second bypass line 71 is provided with a second control valve 72 that controls the flow of hydrogen that flows through the second bypass line 71.

[0116] By opening the second control valve 72, hydrogen to be stored in the hydrogen storage unit 15 is circulated to the hydrogen storage unit 15 via the second bypass line 71, and the hydrogen can be stored in the hydrogen storage unit 15 without passing through the purifier 21. This reduces the pressure loss in the purifier 21.

[0117] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments within the scope of the present invention.

[0118] The hydrogen pressure required by the hydrogen utilization facility 18 is not particularly limited and may be greater than 1 MPa.G, for example, 10 MPa.G. The upper limit pressure of the hydrogen storage unit 15 is also not particularly limited and may be, for example, 20 MPa.G. The hydrogen pressure at which the relief valve 26 opens may be, for example, 1.0 MPa.G.

[0119] The flow rate of the produced hydrogen may be detected directly by a flow meter, or may be calculated from another physical quantity such as the current value of the production device.

[0120] The required hydrogen flow rate may be received as a signal directly from the hydrogen utilization facility as a required value, or may be detected as the required amount of hydrogen = the hydrogen flow rate used by the facility. The method for detecting the hydrogen flow rate used by the facility may be to directly detect the flow rate using a flow meter, or to estimate it from pressure changes in the second supply line or buffer.

[0121] The magnitude relationship between the amount of produced hydrogen and the amount of required hydrogen may be compared by directly detecting the flow rate, or may be estimated from pressure changes in the second supply line or buffer. Alternatively, the magnitude relationship between the amount of produced hydrogen and the amount of required hydrogen may be compared based on the hydrogen flow rate calculated from another physical quantity such as the current value as described above, or the hydrogen flow rate estimated from the pressure changes described above, and any method can be selected.

[0122] <Other> One aspect of the technology disclosed in this specification is described below. [Section 1] a hydrogen generator (11) for generating hydrogen; a compressor (12) for compressing the produced hydrogen; a first line (13) connecting the hydrogen generator and the compressor; a second line (14) connecting the compressor with a hydrogen utilization facility (18) that utilizes the hydrogen pressurized by the compressor; a hydrogen storage unit (15) that stores the hydrogen pressurized by the compressor; a first bypass line (16) connecting the hydrogen storage section and the first line; a first control valve (17) provided in the first bypass line to control the flow of the hydrogen through the first bypass line; A hydrogen production system (10) equipped with [Item 2] a storage pressure sensor (25) that detects the pressure of the hydrogen stored in the hydrogen storage section; a control unit (20) that controls the first control valve; and The control unit receiving a signal of the stored hydrogen pressure from the storage pressure sensor, receiving a signal of the flow rate of hydrogen generated by the hydrogen generation device, and receiving signals of the required hydrogen pressure and required hydrogen flow rate required by the hydrogen utilization facility; Item 1. The hydrogen production system described in item 1, wherein the control unit opens the first control valve at least when the generated hydrogen flow rate is smaller than the required hydrogen flow rate, provided that the stored hydrogen pressure is smaller than a threshold value based on the required hydrogen pressure. [Section 3] a purifier (21) for removing impurities from the hydrogen is disposed in the second line between the compressor and the hydrogen storage section, a second bypass line (71) is provided to connect a portion of the second line between the compressor and the purifier and the hydrogen storage unit so as to bypass the purifier; Item 3. The hydrogen production system according to item 1 or 2, wherein the second bypass line is provided with a second control valve (72) that controls the flow of the hydrogen flowing through the second bypass line. [Section 4] 4. The hydrogen production system according to any one of items 1 to 3, wherein the second line is provided with a buffer (31, 41, 61, 73) that reduces pressure fluctuations of the hydrogen flowing through the second line. [Section 5] Item 5. The hydrogen production system according to item 4, wherein the buffer is a tank capable of storing the hydrogen or a pipe having an inner diameter larger than that of the second line. [Section 6] The hydrogen storage section and the second line are connected by a supply line (23), 6. The hydrogen production system according to any one of items 1 to 5, wherein the supply line is provided with at least one valve (24, 26) for controlling the flow of hydrogen between the hydrogen storage unit and the second line. [Section 6] Item 7. The hydrogen production system according to item 6, wherein at least one of the valves connected to the supply line is a relief valve (26) that allows the hydrogen to flow from the second line to the hydrogen storage unit and prohibits the flow of the hydrogen from the hydrogen storage unit to the second line when the pressure in the second line exceeds a predetermined pressure. [Explanation of symbols]

[0123] 10, 30, 40, 50, 60, Hydrogen production system, 11 Hydrogen generator, 12 Compressor, 13 First line, 14 Second line, 15 Hydrogen storage section, 16 First bypass line, 17 First control valve

Claims

1. A hydrogen generator (11) for generating hydrogen; a compressor (12) for compressing the hydrogen produced; a first line (13) connecting the hydrogen generator and the compressor; a second line (14) connecting the compressor with a hydrogen utilization facility (18) that utilizes the hydrogen pressurized by the compressor; a hydrogen storage unit (15) for storing the hydrogen pressurized by the compressor; a first bypass line (16) connecting the hydrogen storage unit and the first line; a first control valve (17) provided in the first bypass line to control the flow of the hydrogen in the first bypass line; a storage pressure sensor (25) for detecting the pressure of the hydrogen stored in the hydrogen storage section; a control unit (20) that controls the first control valve, The control unit receiving a signal of the stored hydrogen pressure from the storage pressure sensor, receiving a signal of the flow rate of hydrogen generated by the hydrogen generation device, and receiving signals of the required hydrogen pressure and required hydrogen flow rate required by the hydrogen utilization facility; The control unit, at least when the produced hydrogen flow rate is smaller than the required hydrogen flow rate, opens the first control valve, provided that the stored hydrogen pressure is smaller than a threshold value based on the required hydrogen pressure, thereby circulating the hydrogen stored in the hydrogen storage unit, whose stored hydrogen pressure is determined to be smaller than the threshold value, through the first line. This hydrogen production system (10).

2. a purifier (21) for removing impurities from the hydrogen is disposed in the second line between the compressor and the hydrogen storage section, a second bypass line (71) is provided to connect a portion of the second line between the compressor and the purifier and the hydrogen storage unit so as to bypass the purifier; The hydrogen production system according to claim 1, wherein the second bypass line is provided with a second control valve (72) that controls the flow of the hydrogen through the second bypass line.

3. 2. The hydrogen production system according to claim 1, wherein the second line is provided with a buffer (31, 41, 61, 73) that reduces pressure fluctuations of the hydrogen flowing through the second line.

4. The hydrogen production system according to claim 3 , wherein the buffer is a tank capable of storing the hydrogen or a pipe having an inner diameter larger than that of the second line.

5. The hydrogen storage section and the second line are connected by a supply line (23), 2. The hydrogen production system according to claim 1, wherein the supply line is provided with at least one valve (24, 26) for controlling the flow of hydrogen between the hydrogen storage portion and the second line.

6. 6. The hydrogen production system according to claim 5, wherein at least one of the valves connected to the supply line is a relief valve (26) that, when the pressure in the second line exceeds a predetermined pressure, allows the hydrogen to flow from the second line to the hydrogen storage unit and prohibits the hydrogen from flowing from the hydrogen storage unit to the second line.

Images