JP2012117140A - Hydrogen production cell and apparatus for producing hydrogen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the necessity of differential pressure control when producing high-pressure hydrogen by improving pressure resistance performance of a hydrogen producing cell of solid polymer type.SOLUTION: In a hydrogen producing cell 1 where an oxygen-side current collector 12 and a hydrogen-side current collector 13 are arranged on both surfaces of a solid polymer electrolyte membrane 11, the oxygen-side current collector 12 is larger than the hydrogen-side current collector 13, and an edge part of the oxygen-side current collector 12 is positioned at outer side of the edge part of the hydrogen-side current collector 13 extending over the circumference, while an O-ring 22 is arranged at the outer periphery of the hydrogen-side current collector 13, and a position facing the O-ring 22 via the solid polymer electrolyte membrane 11 is inner than the edge part of the oxygen-side current collector 12. Even when positive pressure is applied to the oxygen-side current collector 12 from the hydrogen-side current collector 13 side, the oxygen-side current collector 12 receives the pressure via the solid polymer electrolyte membrane 11, so that the solid polymer electrolyte membrane 11 does not directly receive the pressure, and pressure resistance performance of the whole cell is improved, and the necessity of differential pressure control of the hydrogen-side current collector 13 side and the oxygen-side current collector 12 side is eliminated. The gas between both poles is not blended, too.

Description

  The present invention uses a reversible cell in which a polymer electrolyte water electrolysis device and a fuel cell are integrated (hereinafter, simply referred to as “reversible cell”) or a high-pressure cell using the same type of water electrolysis dedicated cell. It is related to the structure of the hydrogen production cell and the hydrogen production equipment that can produce high-pressure hydrogen with simple control and can improve the reliability, compactness, and cost reduction of water electrolysis equipment. is there. In the present specification, the hydrogen production cell is used to include a reversible cell and a cell dedicated to water electrolysis, and the reversible cell can be used in both a water electrolysis device and a fuel cell, and is dedicated to water electrolysis. The cell can only be used in a water electrolysis apparatus.

  When producing high-pressure hydrogen by electrolysis of water in a reversible cell or a cell exclusively for water electrolysis of the same shape, by controlling the pressure of the gas generated from the cell, hydrogen gas up to several tens of MPa without using a booster, Oxygen gas can be produced. However, in the structure of a solid polymer type reversible cell or a water electrolysis dedicated cell, as is well known, a hydrogen electrode and an oxygen electrode are partitioned by a thin film made of solid polymer (Patent Document 1). Since the thin film has low mechanical strength, the thin film is damaged when an excessive differential pressure is applied between the electrodes. When the thin film is broken, the gas between the two electrodes is mixed, so that a combustion reaction occurs on the catalyst, and in the worst case, the cell may be burned out or exploded. For this reason, the differential pressure control between the electrodes is a very important control in safely performing high-pressure operation of water electrolysis.

  As a method for solving this problem, in the conventional water electrolysis apparatus, two valves, a pressure regulating valve and a leak valve, are provided in the hydrogen gas system and the oxygen gas system so that the differential pressure between the electrodes hardly arises by devising the operation control. Installed on both sides or one side, set the hydrogen and oxygen pressure with the pressure regulating valve, adjust the hydrogen pressure and oxygen pressure with the leak valve, and automatically control the DC current output to the water electrolysis dedicated cell with the DC power supply, hydrogen system The internal pressure and the oxygen system internal pressure are made uniform (Patent Documents 2 and 3). Also, a method has been proposed in which the liquid layers of the pure water storage / gas / liquid separator of both electrodes are connected by piping, and when differential pressure is generated, the differential pressure is eliminated by moving pure water between the two electrodes ( Patent Document 4). Furthermore, it is also proposed that the gas volume of the oxygen side tank be 4% or less of the hydrogen side gas layer volume to prevent the generation of squealing gas even if the gas between both tanks is mixed. Has been.

JP 2009-231094 Japanese Patent No. 3220607 JP 2007-31739 A JP 2003-342773 A

  However, the methods described in Patent Documents 2 and 3 require expensive control equipment for differential pressure control, and it is necessary to devise the device configuration, resulting in higher cost of the device. Moreover, in the technique of patent document 4, not only the detection mechanism of the pressure difference between electrodes is complicated and it is necessary to strictly control a very small amount of water, but also there is a possibility of gas mixing because both electrodes are connected by a pipe. . Furthermore, in the method of managing the ratio of the air volume, the explosion limit value is not reached when viewed as an overall average, but the gas movement occurs in the event of any problem, so if considered locally, it will be on the catalyst. The possibility of reaching the explosion limit is fully considered, and the robustness of control is low, so it is difficult to say that the system is safe.

After all, the above-described operation control and the method of managing the differential pressure between the electrodes below a predetermined value all bear the safety load on the peripheral device side, so there are the following problems. It was.
・ Special equipment is required and the price of the product rises.
・ The volume of the equipment will be enlarged by measures to improve the differential pressure controllability.
・ Because there are many control items, there is concern about abnormal stop or failure due to poor control or cell damage.
・ There is a risk of abnormal stoppage due to erroneous sensor detection.

  The present invention has been made in view of such points, and enables high-pressure hydrogen production with simple control when producing high-pressure hydrogen using a reversible cell or a cell for exclusive use of water electrolysis of the same shape. The purpose is to improve the reliability, downsizing, and cost reduction of hydrogen production equipment that uses CO2.

  The structure of a conventional cell of this type is, for example, as described in Patent Document 1, an oxygen-side collector disposed on both surfaces of a solid polymer electrolyte membrane (MEA) having electrode catalyst layers formed on both surfaces. Since the electric current collector and the hydrogen side current collector are the same size and cannot withstand a large pressure difference (several hundred kPa or more) between the hydrogen and oxygen electrodes, the pressure difference control as described above is performed. I was doing it.

  More specifically, as shown in FIG. 6, the oxygen-side current collector 202 and the hydrogen-side current collector 203 are disposed on both sides of a solid polymer electrolyte membrane 201 in which electrode catalyst layers are formed on both sides and integrated. Each have a configuration in which the separators 205 and 206 forming the flow path 204 are sandwiched, but in practice, a gap is generated between the separator 205 and the oxygen-side current collector 202 in terms of manufacturing accuracy. In such a state, when a positive pressure is applied from the hydrogen side to the oxygen side, that is, through the hydrogen side current collector 203 during hydrogen production, the oxygen side current collector 202 and the separator 205 are placed on the surface (the lower side in FIG. 5). The pressure applied to the solid polymer electrolyte membrane 201 on the side surface) is received by the oxygen-side current collector 202 and the separator 205. If the gap is generated, the separator 205 and the oxygen-side current collector 202 During this time, the pressure applied to the solid polymer electrolyte membrane 201 at the gap position is received by the solid polymer electrolyte membrane 201 as it is, and the membrane is damaged.

  That is, the solid polymer electrolyte membrane 201 originally has sufficient strength against compression, but other mechanical strength is low, so that when tensile stress due to differential pressure is applied, Repeating this causes a creep phenomenon and causes fatigue breakage. Also, if a sharp rigid body is pierced, it can be easily broken. For this reason, conventionally, pressure control as described above has been performed.

  Therefore, the inventor pays attention to such a conventional cell structure, completely changes the idea, and does not make the oxygen side current collector 202 and the hydrogen side current collector 203 the same size. It has been found that the pressure control as described above is not required by increasing the pressure and improving the pressure resistance of the solid polymer electrolyte membrane 201.

  That is, in the present invention, an oxygen-side current collector and a hydrogen-side current collector are disposed on both sides of a solid polymer electrolyte membrane having electrode catalyst layers formed on both sides, and the oxygen-side current collector and the hydrogen-side current collector are arranged. In the hydrogen production cell for producing hydrogen by water electrolysis, the oxygen side current collector has a configuration in which the oxygen side current collector and the hydrogen side current collector are sandwiched by separators arranged on the outer sides of the oxygen side current collector. Larger than the side current collector, the edge of the oxygen side current collector is located outside the edge of the hydrogen side current collector over the entire circumference, and on the outer periphery of the hydrogen side current collector A sealing member having a convex shape with respect to the solid polymer electrolyte membrane and in contact with the solid polymer electrolyte membrane is disposed, and the opposing position of the seal member through the solid polymer electrolyte membrane is the oxygen It is characterized by being on the inner peripheral side from the edge of the side current collector.

  In the hydrogen production cell having such a configuration, the oxygen-side current collector is larger than the hydrogen-side current collector, and the edge of the oxygen-side current collector extends around the entire circumference of the edge of the hydrogen-side current collector. Even if positive pressure is applied from the hydrogen side current collector side to the oxygen side current collector side, all the pressure is passed through the solid polymer electrolyte membrane. Can be taken in terms of That is, according to the prior art of FIG. 6 described above, even if a gap is formed between the separator 205 and the oxygen-side current collector 202, the solid polymer electrolyte membrane 201 itself directly receives the applied pressure. There is no risk of damage to the solid polymer electrolyte membrane. Therefore, the pressure resistance performance is improved as compared with the prior art. As a result, when applied to a hydrogen production apparatus, the conventional differential pressure control becomes unnecessary.

  A sealing member having a convex shape with respect to the solid polymer electrolyte membrane and in contact with the solid polymer electrolyte membrane is disposed on the outer periphery of the hydrogen-side current collector, and the solid polymer electrolyte membrane of the seal member is disposed Since the opposing position is set to be on the inner peripheral side from the edge of the oxygen side current collector, even if the film breaks at the end of the oxygen side current collector, the gas between both electrodes There is no possibility of mixing.

  As the sealing member, a convex portion formed on a sealing material provided so as to surround the outer periphery of the hydrogen side current collector can be applied, and for example, an O-ring provided in a groove of a separator is used. Can do.

  Furthermore, a seal member having a convex shape with respect to the solid polymer electrolyte membrane and being in contact with the solid polymer electrolyte membrane is disposed on the outer periphery of the oxygen side current collector, and the seal member is a hydrogen side current collector. It is preferable that it does not oppose the seal member arrange | positioned on the outer periphery of.

  The hydrogen production apparatus of the present invention is a hydrogen production apparatus using the above-described hydrogen production cell, which stores a power source for supplying power to the hydrogen production apparatus, water used for water electrolysis, and the hydrogen production Oxygen and non-electrolyzed water from the cell are returned, and a first tank that gas-liquid separates inside, and hydrogen and accompanying water from the hydrogen production cell are sent and gas-liquid separated inside. And a tank.

  According to such a hydrogen production apparatus, as described above, since the pressure resistance performance of the hydrogen production cell is improved, the conventional differential pressure control is unnecessary, and therefore, for example, the oxygen side can be set to atmospheric pressure. Of course, a device for performing the differential pressure control is also unnecessary.

  According to the present invention, the pressure resistance performance of the hydrogen production cell is improved. Therefore, in producing high-pressure hydrogen using this cell, high-pressure hydrogen can be produced without performing differential pressure control.

It is explanatory drawing which showed typically the flow-path cross section of the hydrogen production cell concerning embodiment. It is a front view of the separator used for the hydrogen production cell of FIG. It is explanatory drawing which showed typically the system | strain of the hydrogen production apparatus using the hydrogen production cell of FIG. It is explanatory drawing which showed typically the flow-path cross section of the hydrogen production cell concerning other embodiment. It is explanatory drawing which showed typically the flow-path cross section of the hydrogen production cell concerning other embodiment. It is explanatory drawing which showed typically the flow-path cross section of the hydrogen production cell concerning a prior art.

  Embodiments of the present invention will be described below. FIG. 1 schematically shows the inside (planar cross section) of a hydrogen production cell 1 according to the embodiment, and FIG. 2 shows the front of a separator 15 used in the hydrogen production cell 1 described later. In this hydrogen production cell 1, a rectangular oxygen-side current collector 12 and a hydrogen-side current collector 13 are disposed on both sides of a solid polymer electrolyte membrane 11 having electrode catalyst layers formed on both sides. A separator 15 that forms the flow path 14 is disposed outside the oxygen-side current collector 12, and a separator 17 that forms the flow path 16 is disposed outside the hydrogen-side current collector 13.

  In this embodiment, as shown in FIG. 2, the oxygen-side current collector 12 is larger than the hydrogen-side current collector 13 (the area is wide), and the edge of the oxygen-side current collector 12 is It is located outside the edge of the hydrogen-side current collector 13 over the entire circumference.

  A rectangular recess 15a is formed on the inner surface side (solid polymer electrolyte membrane 11 side) of the separator 15, and the oxygen-side current collector 12 is provided in the recess 15a. A groove 15b is formed on the outer peripheral side of the recess 15a in the separator 15, that is, on the outer side of the oxygen-side current collector 12, so as to surround the oxygen-side current collector 12, and an O-ring is formed in the groove 15b. A sealing member 21 such as is provided.

  On the other hand, a rectangular recess 17a is also formed on the inner surface side (solid polymer electrolyte membrane 11 side) of the separator 17, and the hydrogen-side current collector 13 is provided in the recess 17a. A groove 17b is formed on the outer peripheral side of the recess 17a in the separator 17, that is, on the outer side of the hydrogen-side current collector 13, so as to surround the hydrogen-side current collector 13, and an O-ring is formed in the groove 17b. A sealing member 22 such as is provided.

  The shape of the separators 15 and 17 shown in FIGS. 1 and 2 has a thickness of several millimeters, but the material is formed by forming the flow paths 14 and 16 for allowing the reaction fluid to flow on the separator surface. What can provide the recessed parts 15a and 17a for inserting a member by a mold, cutting, etc. is preferable, for example, a resin separator and a metal plate separator can be used. The shape of the separator is not limited to the example shown in FIGS. 1 and 2, and may be a known shape.

  And the position of the sealing member 22 provided in the separator 17 is set to a position facing the surface of the oxygen-side current collector 12 through the solid polymer electrolyte membrane 11 as shown in FIG. That is, the position of the seal member 22 is set so as to be located on the inner side of the edge portion of the oxygen-side current collector 12 through the solid polymer electrolyte membrane 11.

  In FIG. 2, the cooling water manifolds 24 and 25 are located on the left and right sides of the sealing material 21 in the separator 15, and the reaction fluid manifold is also located above the sealing material 21. , 26, 27, and the manifolds 28, 29 for reaction fluid are also located below the sealing material 21. Sealing members 30 such as O-rings are provided on the outer circumferences of the manifolds 24 to 29 so as to surround the manifolds 24 to 29, respectively.

  As shown in FIG. 2, a part of the flow path 14 of the separator 15 communicates with the manifold 26 through the header portion 14 a and a communication hole 31 formed inside the separator 15. The other part of the flow path 14 of the separator 15 communicates with the manifold 29 through the header portion 14 b and a communication hole 32 formed in the separator 15.

  Similarly, a part of the flow path 16 of the separator 17 communicates with the manifold 27 through a header portion (not shown) and a communication hole (not shown) formed in the separator 17. The other part of the flow path 16 of the separator 17 communicates with the manifold 28 through a header portion (not shown) and a communication hole (not shown) formed inside the separator 17.

  Since the hydrogen production cell 1 has the above-described configuration, even if a positive differential pressure is applied from the hydrogen-side current collector 13 to the oxygen-side current collector 12, a solid high pressure is applied. The entire portion of the molecular electrolyte membrane 11 is completely supported only by the plane portion of the oxygen-side current collector 12. Usually, the oxygen-side current collector 12 is made of, for example, a metal non-woven fabric such as titanium or a metal thin plate provided with a plurality of fine holes by photochemical etching or the like, and platinum plating is used. There is no fear of deforming very high. Therefore, there is no portion where the solid polymer electrolyte membrane 11 is deformed, and the surface pressure of the seal member 22 can be secured. That is, the desired reaction force of the seal member 22 is obtained, and a sealing effect corresponding to the reaction force is obtained.

  Even if there is a gap between the end of the oxygen-side current collector 12 and the recess 15a of the separator 15, the oxygen side is at atmospheric pressure, so the force that deforms the film does not act. Furthermore, even if the film breaks at the end of the oxygen-side current collector 12, as shown in FIG. 1, the oxygen-side seal member 21 and the hydrogen-side seal member 22 do not face each other directly. Since the hydrogen-side seal member 22 is disposed on the inner side of the end of the oxygen-side current collector 12, there is no possibility of gas mixing between the two electrodes, and the hydrogen production cell 1 is exposed to the outside. There is no possibility of leakage. Even if there is a gap between the end of the hydrogen-side current collector 13 and the recess 17a of the separator 17, as described above, the oxygen side is at atmospheric pressure, so the oxygen side is pressurized from the oxygen side to the hydrogen side. There is no problem because it is never done.

  In addition, the water electrolysis apparatus in which the hydrogen production cell 1 is used is generally used for high-pressure hydrogen production, and oxygen generated at the same time is exhausted without using it. Therefore, in practice, it is sufficient to pressurize only the hydrogen side, and there is no problem in operation as long as the cell structure has resistance against a positive pressure difference from the hydrogen side to the oxygen side.

  As described above, according to the hydrogen production cell 1 according to the embodiment, even if a positive differential pressure is applied from the hydrogen-side current collector 13 to the oxygen-side current collector 12, the solid polymer electrolyte membrane 11 is not damaged, and gas does not leak out of the cell. According to the inventors' estimation, it is possible to increase the inter-electrode differential pressure resistance to several tens of MPa without changing the strength of the film at all. Therefore, in the conventional device, the safety load that the peripheral device side has borne can all be handled by the cell body, and it is no longer necessary to perform differential pressure control, which was the most important control in the past, and the peripheral device is extremely It can be simplified.

  In order to show this, an example of a hydrogen production apparatus that uses this hydrogen production cell 1 and that does not require the conventional differential pressure control will be described. FIG. 3 shows a system of the hydrogen production apparatus 41. Pure water for water electrolysis supplied to the hydrogen production cell 1 is stored in the pure water storage and gas-liquid separation by driving a pump 43 through a pipe. Supplied from the tank 44 for use. In actual operation, the hydrogen production cell 1 is used as a cell stack configuration in which a plurality of, for example, several tens of the hydrogen production cells 1 are stacked. For convenience of explanation, the hydrogen production cell 1 is represented as the hydrogen production cell 1 in FIG. . That is, the hydrogen production cell 1 shown in FIG. 1 literally shows a cell structure as a minimum unit, but the hydrogen production cell 1 shown in FIG. 3 represents a hydrogen production cell as a cell stack configuration. Yes.

  A part of the pure water from the tank 44 is supplied to the tank 48 through the pipe 47 in order to maintain the quality (purity) of the pure water by the action of the regulating valve V1 and the electromagnetic valve 46.

  A power source 51 is connected to the hydrogen production cell 1, and electrolyzed pure water supplied from the pipe 42 is electrolyzed into hydrogen ions and oxygen ions according to the output. Among them, oxygen ions become oxygen molecules on the catalyst in the hydrogen production cell 1, are discharged out of the cell together with pure water, and are sent to the tank 44 through the pipe 52.

  Hydrogen ions generated by electrolysis move to the hydrogen side in the hydrogen production cell 1 along with accompanying water, become hydrogen molecules on the hydrogen side catalyst, are discharged out of the cell, and are sent to the tank 54 through the pipe 53. The hydrogen gas and oxygen gas sent to the tanks 54 and 44 together with the accompanying water and the electrolyzed pure water that has not been electrolyzed are separated into gas and liquid in each tank. The gas is sent to 56.

  The pure water extracted by gas-liquid separation in the tank 54 is returned to the tank 48 through the pipe 57 using the high pressure in the tank 54. The piping 57 is provided with an adjustment valve V2 and an electromagnetic valve 59.

  The pure water supplied to the tank 48 through the pipes 47 and 57 is sent from the pipe 62 to the pipes 63 and 64 by driving the pump 61. During the water electrolysis operation, the water in the tank 44 is always returned to the tank 48 through the pipe 47 (quantitative drainage system) and a fixed amount of water (water that is slightly dirty by circulating through the apparatus). Then, since the water level of the tank 44 is lowered, it is necessary to supply water to the tank 44 from the tank 48 through the pipe 62 (supply water system). However, the water will gradually become contaminated as it is. Therefore, a certain level of water quality can be maintained by bypassing part of the water supplied to the tank 44 to the pipe 63 (water treatment system). That is, the pipe 63 is a system for maintaining the purity of pure water in the tank 48, and a heat exchanger 65, an ion exchange resin 66, and a filter 67 are provided on the downstream side of the regulating valve V3. This is because, during operation, ion components are generated from the hydrogen production cell 1 and other devices, and the water quality continues to deteriorate as it is, resulting in a decrease in cell performance. It is provided to remove components and maintain water quality. Since the ion-exchange resin 66 normally has a heat-resistant temperature of about 40 ° C., the water supply temperature to the ion-exchange resin 66 is lowered below the heat-resistant temperature by the heat exchanger 65. The filter 67 is provided to remove dust generated in the apparatus, for example, pipe scraping scraps or pump scraps.

  The flow rate control to the pipes 47, 63, 64 is performed by the adjusting valves V1, V3, V4. However, this is not proportional control, and the opening degree is adjusted in advance during trial operation adjustment, and thereafter the flow rate is maintained as it is. The

  The so-called purified water is replenished to the tank 44 through the pipe 64 provided with the regulating valve V4 as reprocessed pure water. The pure water in the tank 44 is supplied again to the hydrogen production cell 1 through the pipe 42.

  Each tank 44, 54 is provided with a corresponding pressure gauge 71, 72, and the pressure in each tank 44, 54 is measured. Regarding the tank 54, the hydrogen system is at a high pressure (for example, 1 MPa (abs: absolute pressure) or higher) during operation, and it is necessary to lower the pressure of the hydrogen system when the operation is stopped. Therefore, the pressure release solenoid valve 80 is provided in the branch pipe 81 connected to the pipe 55. When the operation is stopped, the solenoid valve 80 is opened, whereby the hydrogen system gas can be exhausted to reduce the hydrogen system pressure. At this time, when the pressure of the hydrogen system is lowered to a predetermined value (for example, 0.12 MPa (abs) close to atmospheric pressure), the electromagnetic valve 80 is closed. The pipe 55 is provided with a safety valve 82 connected to the pipe 55 for releasing the pressure when the system pressure is abnormally increased.

  On the other hand, with respect to the tank 44, the pressure gauge 71 is attached to detect any abnormality in the oxygen system, and is used as a sensor for urgently stopping the apparatus.

  The water levels in the tanks 44 and 54 are monitored by the corresponding float type water level gauges 73 and 74, respectively. The electromagnetic valve 59 is controlled by a signal from the water level meter 74 so that the water level in the tank 54 falls within a certain range. In addition, the electromagnetic valve 75 and the pump 61 are controlled by a signal from the water level gauge 73 so that the water level in the tank 44 falls within a certain range.

  The pipe 55 is provided with a gas filter F that removes dust and the like in the gas. A pressure measuring device 77 is provided after the pressure regulating valve 76 (downstream side), and the pressure is supplied to the control device 78. By constantly supplying power from the power source 51 when the pressure drops below a predetermined value, hydrogen production is performed in accordance with the demand side load. That is, if the system pressure on the hydrogen side (pressure measured by the pressure gauge 72) is equal to or lower than the rated pressure, the hydrogen gas discharged to the pipe 55 stays in the system and increases in pressure. Becomes a predetermined value, hydrogen gas is released from the pressure regulating valve 76 and supplied to the demand side. In addition, about the discharge | release of such hydrogen gas, the opening degree of the pressure regulation valve 76 is adjusted previously according to the said predetermined value. The pressure regulating valve 76 is opened when the pressure reaches a predetermined value. When the primary pressure (in-system pressure) reaches a certain value, whether the gas is allowed to flow to the secondary side (outside of the system: demand side). By adjusting the opening degree in advance, the gas flows to the secondary side when the primary side pressure reaches the set pressure. The cell side from the pressure regulating valve 76 is the system internal pressure, and the side opposite to the cell from the pressure regulating valve 76 is the system external pressure. Further, the power supply to the hydrogen production cell 1 is performed by the power supply 51 after being calculated by the control device 78.

  On the other hand, the pipe 56 is provided with a hydrogen concentration meter 85 for measuring the hydrogen concentration in the exhaust oxygen, and safety is monitored. That is, when the hydrogen concentration in oxygen becomes a certain value (4%) or more, a combustion reaction occurs on the electrode catalyst of the hydrogen production cell 1, but when the combustion reaction occurs, the cell is broken. In order to avoid this, the hydrogen concentration in oxygen must be kept below a certain value. In addition, the hydrogen concentration on the oxygen side may increase due to a cell failure (for example, a hole in the solid polymer electrolyte membrane 11). Therefore, in order to monitor whether there is an abnormality in the operation state of the hydrogen production cell 1 itself or the hydrogen production apparatus 41, the hydrogen concentration meter 85 for measuring the hydrogen concentration in the exhaust oxygen described above is provided. For example, when the concentration of hydrogen in oxygen reaches a certain threshold value, for example, 1 to 2% or more, control for stopping the hydrogen production apparatus 41 is performed immediately.

  The hydrogen production apparatus 41 has the above configuration, and an example of its operation will be described next. When starting the hydrogen production apparatus 41, first, the pump 43 is activated, and when the inside of the hydrogen production cell 1 is sufficiently wet, the power source 51 is activated to supply power to the hydrogen production cell 1. Started production of hydrogen.

  During the water electrolysis operation, pure water from the tank 44 is supplied from the tank 44 to the oxygen-side manifold 29 (see FIG. 2) of the hydrogen production cell 1 through the pipe 42 by the pump 43. The pure water is supplied from the manifold 29 to the header portion 14 b of the flow path 14 (see FIG. 2) on the reaction fluid side through the communication hole 32, and is supplied from there to the flow path 14 and the current collector 12. The supplied pure water is electrolyzed on the electrode catalyst of the solid polymer electrolyte membrane 11 according to the amount of current supplied from the power source 51. Oxygen generated by electrolysis and pure water that has not been electrolyzed pass through the header portion 14 a of the flow path 14 and are sent to the manifold 26 from the communication hole 31. The manifold 26 is connected to a pipe 52, and oxygen generated by electrolysis and pure water that has not been electrolyzed are returned to the tank 44.

  The hydrogen generated by the electrolysis and the pure water accompanying the movement of the protons pass through the header portion (not shown) of the flow channel 16 to connect the header portion of the flow channel 16 and the manifold 27 to the separator. It is sent to the manifold 27 through a communication hole (not shown) provided inside. The manifold 27 is connected to a pipe 53, and hydrogen gas generated by electrolysis and pure water accompanying the movement of protons are sent to a tank 54.

  Then, the hydrogen gas separated in the tank 54 is sent to the pipe 55. On the other hand, the pure water extracted by gas-liquid separation in the tank 54 is returned to the tank 48 through the pipe 57 using the pressure in the tank 54.

  When the apparatus is stopped, the electric power from the power source 51 is cut off and the electromagnetic valve 80 is opened to exhaust the hydrogen gas in the system. Then, after the system reaches normal pressure, the pump 43 is stopped. In addition, from the start to the stop, the water level control of the tanks 44 and 54 on both pole sides and the quality of pure water are maintained as usual.

  As described above, according to the hydrogen production apparatus 41 in which the hydrogen production cell 1 is used, no complicated differential pressure control is required through a series of control from start to stop. Therefore, the generated oxygen gas can be exhausted into the atmosphere as it is without passing through the regulating valve. Even when the apparatus is stopped urgently due to some abnormality, the power from the power source 51 is cut off, the pump 43 is stopped, and the solenoid valve 80 is opened at the same time, and no complicated control is required. is there.

  More specifically, conventionally, the operation pressure in a water electrolysis apparatus is generally provided with a pressure regulating valve that opens when the pressure in the system reaches a set pressure, on the both sides of the generated gas or in the vicinity of the apparatus outlet pipe only on the oxygen side. Thus, a method of keeping the pressure in the system at a predetermined pressure is adopted.

  Since water enters and exits the tanks 44 and 54 for pure water storage and gas-liquid separation at each electrode in accordance with the water electrolysis operation, the water level is constantly changing. As a result, the air volume of the tanks 44 and 54 is changed. Is constantly changing. Because differential pressure is generated between the two electrodes due to this change in the air volume and various other factors, the pressure at the high electrode is usually adjusted when a differential pressure of more than a certain value occurs between the two electrodes. The method of adjusting and canceling the differential pressure between both electrodes by the action of a valve or a solenoid valve is taken.

  Since the pressure change accompanying the water level change of the tanks 44 and 54 becomes larger as the gas layer volume is smaller, if operations such as water supply to the tanks 44 and 54, drainage from the tanks 44 and 54, exhaust for pressure adjustment are overlapped, Pressure turbulence becomes severe, and more accurate and highly accurate followability and controllability are required. In particular, when the apparatus is started and stopped, the pressure range for increasing and decreasing pressure is several times that during steady operation, and it is necessary to perform the increasing and decreasing pressure equally in both poles in a short time, so that the control may not function.

  On the other hand, since the hydrogen production cell 41 uses the hydrogen production cell 1 with improved differential pressure tolerance, there is no need for any differential pressure control on the peripheral device side, and the oxygen system is always at normal pressure. As can be seen from FIG. 3, the oxygen-side filter, safety valve, regulating valve, solenoid valve, and pressure regulating valve, which are necessary for the piping 56 on the oxygen exhaust side of the conventional apparatus, are no longer necessary. In addition, the specifications of the oxygen system electromagnetic valves 46 and 75, the pump 43, and the supplementary water pump 61 for the oxygen system can be changed from the high pressure compatible special specification to the normal pressure compatible normal specification. For the hydrogen system, a regulating valve provided on the upstream side of the electromagnetic valve 80 is not necessary.

  Furthermore, the tanks 54 and 44 for water storage and gas-liquid separation on the hydrogen side and oxygen side do not need to have a buffer function for adjusting the differential pressure in the gas layer part. Therefore, it is only necessary to have a water capacity that can reliably control the water level. Therefore, the water tank can be made much smaller than the conventional tank, and as a result, the entire apparatus can be made compact.

  Moreover, in the conventional apparatus, it was necessary to enlarge the tanks 54 and 44 without increasing the hydrogen generation amount of the hydrogen production cell 1, but the hydrogen production apparatus 41 depends on the hydrogen generation amount of the hydrogen production cell 1. No special enlargement is required just by adjusting the amount of water supply and drainage. The downsizing of the tank leads to a reduction in the amount of hydrogen gas, oxygen gas, and water in the system. Therefore, if the hydrogen production cell 1 is damaged, the damage can be reduced and the safety of the device can be improved. Rise.

  And since differential pressure control with the conventional device was necessary in every situation at the time of start, stop, operation, and occurrence of various abnormalities, there are many control items and the control algorithm becomes complicated, as well as the cause of control failure But it was.

  On the other hand, as described above, the hydrogen production apparatus 41 does not require any differential pressure control, so the main control is only the water level control in the tanks 44 and 54 and the power control to the hydrogen production cell 1. There is a simple mechanism and a simple control using a highly reliable sensor. Since the control algorithm can be simplified, the reliability of the apparatus is improved.

The hydrogen production apparatus 41 having the above effects is extremely useful in the following situations.
(1) Hydrogen production with electric power with large fluctuations in power generation In other words, when water electrolysis is performed using electric power with great fluctuations such as solar power generation using solar cells or wind power generation, the amount of power generation is reduced in conventional devices. When water electrolysis is not performed, some measures are necessary so that the hydrogen concentration in oxygen does not increase. Inside the cell dedicated for water electrolysis, there is gas permeation through the polymer membrane according to the partial pressure difference between the electrodes. Concentration increases.
In this case, if the hydrogen concentration on the oxygen side reaches the lower explosion limit concentration, even if there is no abnormality in the cell itself, a combustion reaction occurs on the catalyst and the cell is damaged. In order to prevent this and protect the cell, it is necessary to continue operation with a generation amount of a certain value or more even if there is no hydrogen demand, or exhaust the gas in the system to lower the system pressure. In this apparatus, it was necessary to control the pressure between the two electrodes in order to reduce the system pressure, and it took several minutes or more to reduce the pressure to normal pressure. In addition, bubbles are mixed into the circulation pump due to rapid pressure reduction, resulting in poor circulation of water, and several minutes or more are necessary for the purpose of eliminating the bubbles. Furthermore, even when the pressure is increased again, it is not possible to increase the pressure rapidly, so it took several minutes to reach the rated pressure.
For this reason, conventional devices are not suitable for hydrogen production using fluctuating electric power that is expected to start and stop frequently, and the internal pressure is used to protect the cell from the large amount of gas held in the system. The amount of exhaust hydrogen in the case of lowering the gas also increased, and there was a lot of energy waste.

  On the other hand, in the hydrogen production apparatus 41, since the hydrogen production cell 1 with improved pressure resistance performance is used, when water electrolysis is not performed, the valve is simply opened without any pressure control of the hydrogen gas in the system. It is possible to evacuate only by this, and it is possible to reduce the pressure in the system to normal pressure in a few seconds. In addition, since the amount of hydrogen gas in the system is small, waste of energy can be reduced as compared with the conventional apparatus. In addition, when the pressure is increased again, the pressure can be rapidly increased. Therefore, even after stopping, the system can be restarted instantly, and since the system volume is small, the pressure can be increased to a predetermined pressure within a few seconds to several tens of seconds after the startup. For this reason, it is suitable for the electrolysis using the electric power with which the fluctuation | variation with which starting / stopping occurs frequently is intense.

(2) Hydrogen production in accordance with hydrogen demand As described above, the hydrogen production apparatus 41 can increase the pressure to a predetermined pressure in a short time and can respond to frequent start and stop, so it is supported by a conventional water electrolysis apparatus. In addition to hydrogen demand, in the future, it will be possible to produce hydrogen instantaneously according to hydrogen demand for equipment that requires hydrogen, such as fuel cell vehicles. In addition, the electric power source at that time can use all electric power, such as system electric power, natural energy, such as sunlight and wind power.

  In the hydrogen production cell 1 of the above embodiment, the flow paths 14 and 16 formed in the separators 15 and 17 include grooves formed in the separators 15 and 17, an oxygen-side current collector 12, and a hydrogen-side current collector 13. The hydrogen production cell 101 having the structure shown in FIG. 4 can also be proposed.

  This hydrogen production cell 101 uses a thin metal plate separator as a separator, and FIG. 4 schematically shows a cross section (planar cross section) of the internal flow path. In this hydrogen production cell 101, a rectangular oxygen-side current collector 12 and a hydrogen-side current collector 13 are disposed on both surfaces of a solid polymer electrolyte membrane 11 having electrode catalyst layers formed on both surfaces. Similar to the hydrogen production cell 1 described above, the oxygen-side current collector 12 is larger than the hydrogen-side current collector 13, and the edge of the oxygen-side current collector 12 extends over the entire circumference. It is located outside the 13 edges.

  A separator 103 for forming the reaction channel 102 is disposed outside the oxygen side current collector 12, and a separator 105 for forming the reaction channel 104 is disposed outside the hydrogen side current collector 13. Has been placed. In this example, each flow path is formed by inserting a porous metal mesh into the space between the oxygen-side current collector 12 and the separator 103 and the space between the hydrogen-side current collector 13 and the separator 105, respectively. 102 and 104 are formed. The formation area of each of the flow paths 102 and 104 is larger in the flow path 102 on the oxygen-side current collector 12 side than the flow path 104 of the hydrogen-side current collector 13, and the outer end of the formation area of the flow path 102. The portion is located on the outer side of the outer end of the formation region of the flow path 104. The size of the flow paths 102 and 104 in the formation region is not limited to this.

  It should be noted that portions such as the cooling water channel provided for removing the heat generated by the reaction on the reaction channel side may also be constituted by a metal mesh. Forming these channels with a porous metal mesh is expensive, but has the advantage of simplifying the separator mechanism and the seal shape.

  In the hydrogen production cell 101, seal materials 111 and 112 corresponding to the outer end portion of the oxygen-side current collector 12 and the outer end portion of the hydrogen-side current collector 13 between the separators 103 and 105, respectively. Arranged and sandwiched between separators 103 and 105. On the outer peripheral side of the end portion of the oxygen-side current collector 12 in the sealing material 111, a lip 111a projecting from the solid polymer electrolyte membrane 11 is formed so as to surround the oxygen-side current collector 12, On the outer peripheral side of the end portion of the hydrogen-side current collector 13 in the sealing material 112, a lip 112 a projecting from the solid polymer electrolyte membrane 11 is formed so as to surround the hydrogen-side current collector 13. The lip 112 a faces the peripheral portion of the oxygen-side current collector 12 through the solid polymer electrolyte membrane 11. The lips 111a and 112a can be easily formed by integrally molding with the sealing materials 111 and 112 using, for example, a mold.

  These sealing materials 111 and 112 are integrated with the separators 103 and 105 by baking, injection molding, or the like, or grooves are formed in the separators 103 and 105 by press work, and the sealing members are embedded in the portions, thereby the internal pressure is applied to the sealing members. It is preferable to have a structure in which the seal member does not move outwards even when applied.

  According to the hydrogen production cell 101 having such a configuration, the end positions of the flow paths 102 and 104 and the end positions of the oxygen-side current collector 12 and the hydrogen-side current collector 13 are determined in accordance with the polymerization direction of each member (FIG. 4). The oxygen-side current collector 12 and the hydrogen-side current collector 13 that are not overlapped with each other and smoother in cross-section than the channels 102 and 104 that are uneven in cross-section are viewed from the upper and lower directions. As a whole, the solid polymer electrolyte membrane 11 is sandwiched between a smooth current collector and a seal member. Therefore, the sealing materials 111 and 112 are not deformed to enter the flow paths 102 and 104 to cause a problem such as an increase in flow path pressure loss, and the sealing surface pressure does not decrease by entering. Therefore, as with the hydrogen production cell 1 described above, it is possible to ensure resistance to a positive pressure difference from the hydrogen side to the oxygen side.

  Further, in the hydrogen production cell 101 having the above-described configuration, the flow paths 102 and 104 are formed by inserting porous metal meshes into the space between the separators 105, so that the thickness is uniform over the entire surface. Can be produced. In addition, since the contact with the current collector becomes uniform, the conductor resistance is lowered, and hydrogen can be produced with high efficiency. In addition, the thickness of the separator constituting the flow path can be made thin and light, and there is also an advantage that the initial cost is not required because a mold is not required.

  Furthermore, the hydrogen production cell 151 shown in FIG. 5 can also be proposed. This hydrogen production cell 151 uses separators 152 and 153 obtained by press-molding a metal thin plate into a corrugated plate shape, and seal materials 111 and 112 are integrated into the separators 152 and 153 by baking or injection molding. is there. The space formed between the oxygen-side current collector 12 and the separator 152 becomes the oxygen-side reaction flow path 14c, and the space formed outside the separator 152 (in fact, another hydrogen production cell having the same shape). Formed by the separator of the other hydrogen production cell 151) becomes the cooling water flow path 14d flowing on the oxygen-side back surface. Similarly, the space formed between the hydrogen-side current collector 13 and the separator 153 becomes the hydrogen-side reaction flow path 16c, and the space formed outside the separator 153 (actually, other hydrogen of the same shape). When the production cells 151 are stacked, the separator of the other hydrogen production cell 151 forms a cooling water flow path 16d that flows on the rear surface on the hydrogen side. Of course, like the hydrogen production cells 1 and 101 described above, the oxygen-side current collector 12 is larger than the hydrogen-side current collector 13, and the edge of the oxygen-side current collector 12 extends to the hydrogen side over the entire circumference. It is located outside the edge of the current collector 13.

  Further, in this hydrogen production cell 151, an identical lip 111b protruding outward is provided at a position corresponding to the lip 111a on the outer side of the sealing material 111. The lip 111b is for ensuring the airtightness of the flow path of the cooling water when the hydrogen production cells 151 are stacked to form a stack structure.

  According to the hydrogen production cell 151 having such a configuration, since the separator that forms the flow path can be easily manufactured by press working, it is suitable for mass production, thereby making it possible to reduce the unit price per sheet. .

  The present invention is also applicable to a reversible cell in which a solid polymer water electrolyzer and a fuel cell are integrated.

  The present invention is useful when producing high-pressure hydrogen using water electrolysis.

DESCRIPTION OF SYMBOLS 1 Hydrogen production cell 11 Solid polymer electrolyte membrane 12 Oxygen side collector 13 Hydrogen side collector 14, 16 Flow path 15, 17 Separator 21, 22 O-ring

Claims (5)

Separator in which an oxygen-side current collector and a hydrogen-side current collector are arranged on both sides of a solid polymer electrolyte having electrode catalyst layers formed on both sides, and are arranged on the outer sides of the oxygen-side current collector and the hydrogen-side current collector. In the hydrogen production cell having a configuration in which the oxygen side current collector and the hydrogen side current collector are sandwiched, and producing hydrogen by water electrolysis,
The oxygen-side current collector is larger than the hydrogen-side current collector, and the edge of the oxygen-side current collector is located outside the edge of the hydrogen-side current collector over the entire circumference.
A seal member that has a convex shape with respect to the solid polymer electrolyte membrane and is in contact with the solid polymer electrolyte membrane is disposed on an outer periphery of the hydrogen-side current collector, and the solid polymer electrolyte of the seal member The hydrogen production cell characterized in that the opposing position through the membrane is on the inner peripheral side from the edge of the oxygen-side current collector. 2. The hydrogen production cell according to claim 1, wherein the sealing member is a convex portion formed on a sealing material provided so as to surround an outer periphery of the hydrogen-side current collector. The hydrogen production cell according to claim 1, wherein the seal member is an O-ring provided in a groove of the separator. A seal member having a convex shape with respect to the solid polymer electrolyte membrane and in contact with the solid polymer electrolyte membrane is disposed on the outer periphery of the oxygen side current collector, and the seal member is disposed on the outer periphery of the hydrogen side current collector. The hydrogen production cell according to any one of claims 1 to 3, wherein the hydrogen production cell is not opposed to the seal member disposed in the area. A hydrogen production apparatus using the hydrogen production cell according to claim 1,
A power supply for supplying power to the hydrogen production device;
A first tank for storing water to be used for water electrolysis and for returning oxygen and non-electrolyzed water from the hydrogen production cell, and for gas-liquid separation inside;
A second tank in which hydrogen and accompanying water from the hydrogen production cell is sent and gas-liquid separated inside;
An apparatus for producing hydrogen, comprising:

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