JP5613084B2 - Water electrolysis system - Google Patents

Description

  The present invention is provided in a water electrolysis apparatus that electrolyzes water to generate oxygen and high-pressure hydrogen having a pressure higher than that of oxygen, and a hydrogen pipe that discharges the high-pressure hydrogen from the water electrolysis apparatus, A gas-liquid separator that separates the water contained in the gas, a high-pressure hydrogen lead-out line that leads out the high-pressure hydrogen from which water has been separated from the gas-liquid separator, and high-pressure water that discharges high-pressure water from the gas-liquid separator The present invention relates to a water electrolysis system including a discharge line and a control device.

  Generally, hydrogen is used as a fuel gas used for a power generation reaction of a fuel cell. This hydrogen is produced by, for example, a water electrolysis device. The water electrolysis apparatus uses a solid polymer electrolyte membrane (ion exchange membrane) in order to decompose water and generate hydrogen (and oxygen). Electrode catalyst layers are provided on both sides of the solid polymer electrolyte membrane to form an electrolyte membrane / electrode structure, and power supply bodies are disposed on both sides of the electrolyte membrane / electrode structure to provide unit cells. Is configured.

  Therefore, a cell unit in which a plurality of unit cells are stacked is supplied with voltage at both ends in the stacking direction, and water is supplied to the anode-side power feeding body. For this reason, water is decomposed and hydrogen ions (protons) are generated on the anode side of the electrolyte membrane / electrode structure, and the hydrogen ions permeate the solid polymer electrolyte membrane and move to the cathode side to bond with electrons. Thus, hydrogen is produced. On the other hand, on the anode side, oxygen generated together with hydrogen is discharged from the cell unit together with excess water.

  In the water electrolysis apparatus described above, hydrogen containing moisture is produced, and in order to obtain a dry state, for example, 5 ppm or less of hydrogen (hereinafter also referred to as dry hydrogen), it is necessary to remove moisture from the hydrogen. .

  At that time, in a high-pressure hydrogen production apparatus in which hydrogen at a pressure higher than oxygen (for example, 1 MPa or more) is obtained on the cathode side, there is a problem that a gas-liquid separation apparatus for removing moisture from the high-pressure hydrogen becomes large.

  Therefore, for example, a gas-liquid separator disclosed in Patent Document 1 is known. As shown in FIG. 5, the gas-liquid separation device includes a pressure vessel 2 to which a hydrogen conduit 1 is connected, a water level sensor 3 that detects a water level in the pressure vessel 2, and a ceiling portion of the pressure vessel 2. A hydrogen extraction conduit 4a serving as the connected hydrogen extraction means 4 and a drainage conduit 5a serving as the drainage means 5 connected to the bottom of the pressure vessel 2 are provided.

  The hydrogen extraction conduit 4 a is provided with a first back pressure valve 6 and an electromagnetic valve 7 on the downstream side of the first back pressure valve 6. The drainage conduit 5a is provided with a second back pressure valve 8.

  The first back pressure valve 6 is set to open at, for example, 35 MPa, and the second back pressure valve 8 is set to open at a higher pressure than the first back pressure valve 6, for example, at 36 MPa. ing. The electromagnetic valve 7 operates upon receiving a detection signal from the water level sensor 3, and opens when the water level detected by the water level sensor 3 reaches a predetermined low water level, and closes when the water level reaches a predetermined high water level. doing.

  When the solenoid valve 7 is closed, the extraction of the high-pressure hydrogen gas from the hydrogen extraction conduit 4a is forcibly stopped, so that the pressure in the pressure-resistant vessel 2 is 35 MPa, which is the set pressure of the first back pressure valve 6. It becomes higher than As a result, the second back pressure valve 8 is opened each time the pressure in the pressure vessel 2 reaches its set pressure of 36 MPa, and liquid water is intermittently discharged from the drainage conduit 5a via the second back pressure valve 8. Have been discharged.

JP 2006-347779 A

  In the above water electrolysis system, when the second back pressure valve 8 is opened and liquid water passes through the second back pressure valve 8 and is discharged from the drainage conduit 5a, the pressure of the water is reduced at once. ing. For this reason, the load applied to the second back pressure valve 8 tends to increase, and the durability of the second back pressure valve 8 may be reduced.

  The present invention solves this type of problem, suppresses the rapid discharge of high-pressure water from the gas-liquid separator, and improves the durability of the solenoid valve with a simple and economical configuration. It is an object of the present invention to provide a water electrolysis system that can be used.

  The present invention is provided in a water electrolysis apparatus that electrolyzes water to generate oxygen and high-pressure hydrogen having a pressure higher than that of oxygen, and a hydrogen pipe that discharges the high-pressure hydrogen from the water electrolysis apparatus, A gas-liquid separator that separates the water contained in the gas, a high-pressure hydrogen lead-out line that leads out the high-pressure hydrogen from which water has been separated from the gas-liquid separator, and high-pressure water that discharges high-pressure water from the gas-liquid separator The present invention relates to a water electrolysis system including a discharge line and a control device.

This water electrolysis system, the high-pressure hydrogen outlet line, a first back-pressure valve set to the first pressure is provided to the high-pressure water discharge line, a solenoid valve for opening and closing operation by the opening and closing signals from the control device, wherein Positioned downstream of the solenoid valve, between the solenoid valve and the pressure loss generator, a pressure loss generator that applies pressure loss to the water flowing through the high-pressure water discharge line, and lower than the first pressure A second back pressure valve set to a second pressure, and the control device closes the solenoid valve by a close signal when determining that the water level of the gas-liquid separation device has dropped to a set lower position, When it is determined that the water level has risen to the set upper position, the solenoid valve is opened by an open signal.

  According to the present invention, when the electromagnetic valve provided in the high-pressure water discharge line is opened, the gas-liquid separation device communicates with the pressure loss generating unit. For this reason, a large pressure difference is not caused before and after opening and closing of the electromagnetic valve, and it is possible to reliably prevent high-pressure water from flowing rapidly along the high-pressure water discharge line. Accordingly, the durability of the solenoid valve can be improved satisfactorily with a simple and economical configuration.

It is a schematic structure explanatory view of a water electrolysis system concerning a 1st embodiment of the present invention. It is a relation explanatory view of the position and pressure of the high-pressure water discharge line which constitutes the water electrolysis system. It is a schematic structure explanatory drawing of the water electrolysis system concerning a 2nd embodiment of the present invention. It is a relation explanatory view of the position and pressure of the high-pressure water discharge line which constitutes the water electrolysis system. It is explanatory drawing of the gas-liquid separation apparatus currently disclosed by patent document 1. FIG.

  As shown in FIG. 1, the water electrolysis system 10 according to the first embodiment of the present invention electrolyzes water (pure water) to generate oxygen and high-pressure hydrogen (higher than normal-pressure oxygen pressure, 1 to 70 MPa hydrogen) and a water reservoir for separating the oxygen and excess water discharged from the water electrolyzer 12 and storing the water An apparatus 14, a water circulation apparatus 16 for circulating the water stored in the water storage apparatus 14 to the water electrolysis apparatus 12, and a water supply apparatus for supplying pure water generated from city water to the water storage apparatus 14 18, a gas-liquid separator 22 that removes moisture contained in the high-pressure hydrogen led out from the water electrolyzer 12 to the high-pressure hydrogen pipe 20, and the high-pressure hydrogen from which water has been separated from the gas-liquid separator 22 High pressure to derive It comprises a hydrogen outlet line 24, a high-pressure water discharge line 26 for discharging the high-pressure water from the gas-liquid separator 22, a controller (control unit) 28.

  The water electrolysis apparatus 12 includes a cell unit in which a plurality of unit cells 30 are stacked. At one end in the stacking direction of the unit cells 30, a terminal plate 32a, an insulating plate 34a, and an end plate 36a are sequentially arranged outward. Similarly, a terminal plate 32b, an insulating plate 34b, and an end plate 36b are sequentially disposed on the other end in the stacking direction of the unit cells 30 toward the outside. The end plates 36a and 36b are integrally clamped and held.

  Terminal portions 38a and 38b are provided on the side portions of the terminal plates 32a and 32b so as to protrude outward. The terminal portions 38a and 38b are electrically connected to the electrolytic power source 40 via the wirings 39a and 39b.

  The unit cell 30 includes a disk-shaped electrolyte membrane / electrode structure 42, and an anode-side separator 44 and a cathode-side separator 46 that sandwich the electrolyte membrane / electrode structure 42. The anode-side separator 44 and the cathode-side separator 46 have a disk shape and are made of, for example, a carbon member or the like, or are used for corrosion protection on a steel plate, a stainless steel plate, a titanium plate, an aluminum plate, a plated steel plate, or a metal surface thereof. The metal plate that has been subjected to the above surface treatment is press-molded or cut and subjected to a corrosion-resistant surface treatment.

  The electrolyte membrane / electrode structure 42 includes, for example, a solid polymer electrolyte membrane 48 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode-side power feeder 50 and a cathode provided on both surfaces of the solid polymer electrolyte membrane 48. Side power supply body 52.

  An anode electrode catalyst layer 50 a and a cathode electrode catalyst layer 52 a are formed on both surfaces of the solid polymer electrolyte membrane 48. The anode electrode catalyst layer 50a uses, for example, a Ru (ruthenium) -based catalyst, while the cathode electrode catalyst layer 52a uses, for example, a platinum catalyst.

  The outer peripheral edge of the unit cell 30 communicates with each other in the stacking direction to supply water (pure water), water supply communication holes 56, oxygen generated by the reaction, and unreacted water (mixed fluid). A discharge communication hole 58 for discharging hydrogen and a hydrogen communication hole 60 for flowing hydrogen produced by the reaction are provided.

  A surface of the anode separator 44 facing the electrolyte membrane / electrode structure 42 is provided with a first flow path 64 communicating with the water supply communication hole 56 and the discharge communication hole 58. The first flow path 64 is provided within a range corresponding to the surface area of the anode-side power supply body 50 and is configured by a plurality of flow path grooves, a plurality of embosses, and the like. In the first flow path 64, oxygen generated by the reaction and used water flow.

  A second flow path 68 communicating with the hydrogen communication hole 60 is formed on the surface of the cathode separator 46 facing the electrolyte membrane / electrode structure 42. The second flow path 68 is provided in a range corresponding to the surface area of the cathode-side power feeder 52, and includes a plurality of flow path grooves, a plurality of embosses, and the like. High-pressure hydrogen generated by the reaction flows through the second flow path 68.

  The water circulation device 16 includes a circulation pipe 72 that communicates with the water supply communication hole 56 of the water electrolysis device 12, and the circulation pipe 72 includes a circulation pump 74 and an ion exchanger 76 that constitute a water storage device 14. Connected to the bottom of section 78.

  One end portion of the return pipe 80 communicates with the upper portion of the tank portion 78, and the other end of the return pipe 80 communicates with the discharge communication hole 58 of the water electrolysis apparatus 12. One end of the return pipe 80 is set to a position that always opens in the water stored in the tank portion 78.

  A pure water supply pipe 84 connected to the water supply device 18 and an oxygen exhaust pipe 86 for discharging oxygen separated from the pure water in the tank section 78 are connected to the tank section 78.

  One end of the high-pressure hydrogen pipe 20 is connected to the hydrogen communication hole 60 of the water electrolysis apparatus 12, and the other end of the high-pressure hydrogen pipe 20 is connected to the gas-liquid separator 22. The high-pressure hydrogen from which moisture has been removed by the gas-liquid separator 22 is led out to the high-pressure hydrogen lead-out line 24 as dry hydrogen. The high pressure hydrogen lead-out line 24 is provided with a first back pressure valve 88 set to a first pressure value (for example, 35 MPa).

  The gas-liquid separator 22 includes a tank unit 90 for storing water. The tank unit 90 is provided with a water level detection unit, for example, a water level detection sensor 92 that detects whether or not the water level WS in the tank unit 90 is a set height. A detection signal from the water level detection sensor 92 is input to the controller 28.

  A high-pressure water discharge line 26 is connected to the lower part of the gas-liquid separator 22. The high-pressure water discharge line 26 is provided on the downstream side of the electromagnetic valve 94 and an electromagnetic valve 94 that opens and closes in response to an open / close signal from a controller 28. And a pressure loss generating unit, for example, a flow rate adjusting valve 98, which is provided downstream of the second back pressure valve 96 and applies pressure loss to the water flowing through the high pressure water discharge line 26.

  The second back pressure valve 96 is set to a second pressure (for example, 34 MPa) lower than the first pressure (for example, 35 MPa) of the first back pressure valve 88. Note that the second back pressure valve 96 can be omitted.

  The operation of the water electrolysis system 10 configured as described above will be described below.

  First, when the water electrolysis system 10 is started, pure water generated from city water is supplied to the tank unit 78 constituting the water storage device 14 via the water supply device 18.

  In the water circulation device 16, the water in the tank unit 78 is supplied to the water supply communication hole 56 of the water electrolysis device 12 through the circulation pipe 72 under the action of the circulation pump 74. On the other hand, a voltage is applied to the terminal portions 38a and 38b of the terminal plates 32a and 32b via the electrolytic power supply 40 that is electrically connected.

  Therefore, in each unit cell 30, water is supplied from the water supply communication hole 56 to the first flow path 64 of the anode side separator 44, and this water moves along the anode side power supply body 50.

  Therefore, water is decomposed by electricity in the anode electrode catalyst layer 50a, and hydrogen ions, electrons, and oxygen are generated. Hydrogen ions generated by this anodic reaction permeate the solid polymer electrolyte membrane 48 and move to the cathode electrode catalyst layer 52a side, and combine with electrons to obtain hydrogen.

  Thereby, hydrogen flows along the second flow path 68 formed between the cathode-side separator 46 and the cathode-side power feeder 52. This hydrogen is maintained at a higher pressure than the water supply communication hole 56 and can flow out of the water electrolysis apparatus 12 through the hydrogen communication hole 60.

  On the other hand, oxygen generated by the reaction and unreacted water flow through the first flow path 64, and these mixed fluids are discharged to the return pipe 80 of the water circulation device 16 along the discharge communication hole 58. The After the unreacted gas water and oxygen are introduced into the tank unit 78 and separated, the water is introduced from the circulation pipe 72 through the ion exchanger 76 to the water supply communication hole 56 via the circulation pump 74. The Oxygen separated from the water is discharged to the outside from the oxygen exhaust pipe 86.

  The hydrogen generated in the water electrolysis device 12 is sent to the gas-liquid separation device 22 via the high-pressure hydrogen pipe 20. In the gas-liquid separator 22, water vapor (water) contained in hydrogen is separated from the hydrogen and stored in the tank unit 90, while the hydrogen is led out to the high-pressure hydrogen lead-out line 24.

  The tank unit 90 includes a water level detection sensor 92 for detecting whether or not the water level WS in the tank unit 90 is a set height. When the controller 28 determines that the water level WS has dropped to the set lower position via the water level detection sensor 92, the controller 28 instructs the stop of drainage from the tank unit 90 to the high-pressure water discharge line 26. That is, the electromagnetic valve 94 is closed. On the other hand, when the controller 28 determines that the water level WS has risen to the set upper position, the controller 28 opens the electromagnetic valve 94 and instructs the high pressure water discharge line 26 to drain.

  In this case, in the first embodiment, a second back pressure valve 96 is disposed downstream of the electromagnetic valve 94, and a flow rate adjusting valve 98 is disposed downstream of the second back pressure valve 96. Accordingly, when the electromagnetic valve 94 is opened, a pressure drop is caused in the electromagnetic valve 94 up to a second pressure (for example, 34 MPa) which is a set pressure of the second back pressure valve 96 (see FIG. 2). Furthermore, a rapid pressure drop in the high-pressure water discharge line 26 does not occur under the throttle (opening adjustment) action of the flow control valve 98.

  As described above, when the electromagnetic valve 94 provided in the high-pressure water discharge line 26 is opened, the inside of the tank portion 90 of the gas-liquid separation device 22 communicates with the flow rate adjusting valve (pressure loss generating portion) 98. For this reason, a large pressure difference does not occur before and after the electromagnetic valve 94 is opened and closed, and high-pressure water can be reliably prevented from flowing along the high-pressure water discharge line 26. Therefore, it is possible to obtain an effect that the durability of the electromagnetic valve 94 can be improved satisfactorily with a simple and economical configuration.

  In addition, a second back pressure valve 96 is disposed in the high pressure water discharge line 26 between the electromagnetic valve 94 and the flow rate adjustment valve 98. The second pressure that is the set pressure of the second back pressure valve 96 is set to a value that is slightly smaller than the first pressure that is the set pressure of the first back pressure valve 88. Specifically, the first pressure is 35 MPa, while the second pressure is 34 MPa.

  Thereby, when draining in the high-pressure water discharge line 26, that is, when the electromagnetic valve 94 is opened, the pressure difference applied to the electromagnetic valve 94 can be reduced, and the influence on the electromagnetic valve 94 can be eliminated well. It becomes possible.

  FIG. 3 is a schematic configuration explanatory view of a water electrolysis system 110 according to the second embodiment of the present invention. In addition, the same reference number is attached | subjected to the component same as the water electrolysis system 10 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted.

  The water electrolysis system 110 is provided with a solenoid valve 94, a second back pressure valve 96, and a pressure loss generator, for example, a fine tube 112, along the flow direction of the high-pressure water discharge line 26. Note that a column (not shown) may be used in place of the fine tube 112 as the pressure loss generating portion.

  In the second embodiment configured as described above, the second back pressure valve 96 is disposed downstream of the electromagnetic valve 94, and the fine tube 112 is disposed downstream of the second back pressure valve 96. ing.

  Therefore, when the solenoid valve 94 is opened, as shown in FIG. 4, a large pressure difference does not occur before and after the solenoid valve 94 is opened and closed, and high-pressure water rapidly flows along the high-pressure water discharge line 26. It can be surely prevented from flowing. As a result, the same effects as those of the first embodiment can be obtained, such as the durability of the electromagnetic valve 94 can be improved satisfactorily with a simple and economical configuration.

  Furthermore, in the second embodiment, since the fine tube 112 (or column) is used as the pressure loss generating portion, there is an advantage that the cost is further reduced. In the second embodiment, the second back pressure valve 96 can be deleted.

DESCRIPTION OF SYMBOLS 10, 110 ... Water electrolysis system 12 ... Water electrolysis apparatus 14 ... Water storage apparatus 16 ... Water circulation apparatus 18 ... Water supply apparatus 20 ... High-pressure hydrogen piping 22 ... Gas-liquid separation apparatus 24 ... High-pressure hydrogen derivation line 26 ... High-pressure water discharge line 28 ... Controller 30 ... Unit cell 42 ... Electrolyte membrane / electrode structure 44 ... Anode side separator 46 ... Cathode side separator 48 ... Solid polymer electrolyte membrane 50 ... Anode side power supply body 52 ... Cathode side power supply element 56 ... Water supply communication hole 58 ... discharge communication hole 60 ... hydrogen communication holes 88 and 96 ... back pressure valves 78 and 90 ... tank section 92 ... water level detection sensor 94 ... solenoid valve 98 ... flow control valve 112 ... fine tube

Claims (1)

A water electrolysis device that electrolyzes water to generate oxygen and high-pressure hydrogen that is higher in pressure than the oxygen;
A gas-liquid separator that is disposed in a hydrogen pipe that discharges the high-pressure hydrogen from the water electrolyzer and separates water contained in the high-pressure hydrogen;
A high-pressure hydrogen outlet line for extracting the high-pressure hydrogen from which water has been separated from the gas-liquid separator;
A high-pressure water discharge line for discharging high-pressure water from the gas-liquid separator;
A control device;
A water electrolysis system comprising:
The high-pressure hydrogen lead-out line is provided with a first back pressure valve set at a first pressure,
In the high-pressure water discharge line , an electromagnetic valve that opens and closes by an open / close signal from the control device;
A pressure loss generating unit that is located downstream of the solenoid valve and applies pressure loss to water flowing through the high pressure water discharge line;
A second back pressure valve located between the electromagnetic valve and the pressure loss generating unit and set to a second pressure lower than the first pressure;
The control device closes the solenoid valve by a close signal when it is determined that the water level of the gas-liquid separator is lowered to a set lower position, and an open signal when it is determined that the water level is raised to a set upper position. Opening the solenoid valve;
A water electrolysis system characterized by that.

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