Electrolysis apparatus and electrolysis method

Abstract

To provide a technique by which a device can achieve its miniaturization.SOLUTION: A water electrolysis apparatus 1A which generates a gas by electrolyzing a liquid supplied to an electrolyte membrane arranged between an anode side electrode part and a cathode side electrode part, comprises: a liquid supply chamber in which the cathode side electrode part is arranged, and to which the liquid is supplied; a hydrophobic membrane which forms a diaphragm of a part of the liquid supply chamber, and transmits only a gas generated on the cathode side of the electrolyte membrane by electrolysis; and a discharge passage which discharges the gas transmitted through the hydrophobic membrane to the outside.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present invention relate to techniques for separating liquid and gas from a multiphase fluid. [Background technology]

[0002] Conventionally, a gas-liquid separator for separating gas and liquid from a multiphase fluid of gas and liquid is disclosed in the following Patent Document 1. In the gas-liquid separator disclosed in the above, a swirling vane is disposed in an annular space formed by a main body and an exhaust pipe, and the upper part of the annular space is connected to an inlet, and the upper part is connected to an outlet through a hole inside the exhaust pipe. In addition, a swirling chamber is formed below the annular space, and a liquid reservoir chamber is formed below the swirling chamber, and a gap for liquid passage is formed between the outer periphery of the partition member and the inner periphery wall of the casing. According to such a gas-liquid separator, the multiphase fluid entering from the inlet is swirled by the swirling vane, and the liquid is swung outward by the action of centrifugal force and separated, and flows down along the inner periphery wall of the main body and flows into the liquid reservoir chamber through the gap. Meanwhile, the gas that has passed through the lower end of the exhaust pipe flows out from the outlet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-028422 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned gas-liquid separation device requires an annular space in which the swirl vanes are provided, a swirl chamber, a liquid reservoir chamber, etc., and therefore has a problem in that the device is large in scale.

[0005] The problem to be solved by the present invention is to provide a technique that can realize miniaturization of an apparatus. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one aspect of the present invention is an electrolysis device that generates gas by electrolyzing a liquid supplied to an electrolyte membrane between an anode side electrode part and a cathode side electrode part, and is characterized in comprising: a liquid supply chamber in which the cathode side electrode part is arranged and to which the liquid is supplied; a hydrophobic membrane that forms a partition wall of a part of the liquid supply chamber and allows permeation of only gas generated on the cathode side of the electrolyte membrane by the electrolysis; and a discharge path that discharges the gas that has permeated the hydrophobic membrane to the outside. [Brief description of the drawings]

[0007] [Figure 1] 1 is a perspective view showing a gas-liquid separation device according to a first embodiment. [Diagram 2] 1 is a front view showing a gas-liquid separation device according to a first embodiment. [Diagram 3] 3 is a cross-sectional view taken along line AA shown in FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along line BB shown in FIG. [Diagram 5] 1 is a schematic diagram for explaining an internal configuration and a fluid flow of a gas-liquid separation device according to a first embodiment. FIG. [Figure 6] FIG. 4 is a perspective view showing a water electrolysis apparatus according to a second embodiment. [Figure 7] FIG. 1 is a perspective view showing a unit electrolytic cell according to a second embodiment. [Figure 8] FIG. 1 is a front view showing a unit electrolytic cell according to a second embodiment. [Figure 9] FIG. 11 is a right side view showing a unit electrolytic cell according to a second embodiment. [Figure 10] FIG. 1 is a left side view showing a unit electrolytic cell according to a second embodiment. [Figure 11] FIG. 11 is an exploded side view illustrating the configuration of a unit electrolytic cell according to a second embodiment. [Figure 12] FIG. 11 is a schematic diagram for explaining the internal configuration and fluid flow of an electrolysis cell according to a second embodiment. [Figure 13] FIG. 4 is a schematic diagram illustrating the internal configuration and fluid flows of a water electrolysis cell according to a first modified example. [Figure 14] FIG. 11 is a schematic diagram illustrating the internal configuration and fluid flows of a water electrolysis cell according to a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification and the drawings, components having substantially the same functions are denoted by the same reference numerals, and redundant description will be omitted.

[0009] (First embodiment) The configuration of the gas-liquid separation device according to this embodiment will be described. The gas-liquid separator according to this embodiment will be described below assuming that the multiphase fluid to be separated is a two-phase gas-liquid fluid in which liquid such as water and gas (bubbles) such as air or water vapor are mixed. Figures 1 and 2 are a perspective view and a front view showing the gas-liquid separation device according to this embodiment. Figures 3 and 4 are cross-sectional views taken along lines AA and BB in Figure 2.

[0010] As shown in Fig. 1, the gas-liquid separation device 1 according to this embodiment includes a liquid side plate 20 located on the front side of the device, a gas side plate 30 located on the rear side, and a gas-liquid mixing plate 40 located between these plates and connected to each plate, each of which is formed in a substantially disk shape. The plates are stacked on top of each other and fastened together with fasteners such as bolts and nuts, thereby being connected together. By connecting these plates together, flow paths are formed between the plates through which the multiphase fluid, the liquid separated from the multiphase fluid, and the gas separated from the multiphase fluid each flow separately. The flow paths will be described in detail later.

[0011] 1 and 2, the liquid side plate 20 is provided with two supply and exhaust pipes 41a, 41b, one liquid exhaust pipe 21, and one gas exhaust pipe 31 on its flat surface edge. Hereinafter, when there is no need to distinguish between them, they will be referred to as pipe sections. Each pipe section is formed in a substantially cylindrical shape protruding outward from the surface of the liquid side plate 20, and in this embodiment, they are arranged in the following order clockwise when viewed from the front, the supply and exhaust pipe 41a, the gas exhaust pipe 31, the supply and exhaust pipe 41b, and the liquid exhaust pipe 21, at equal intervals in the circumferential direction.

[0012] 3 and 4, the gas side plate 30 is provided with two supply and exhaust pipes 41a, 41b, one liquid exhaust pipe 21, and one gas exhaust pipe 31 on its flat rear edge. These pipe sections are of the same type as the pipe sections in the liquid side plate 20, and are provided on the rear side of the pipe sections in the liquid side plate 20. The same type of pipe sections located at corresponding positions on the front side and rear side of the gas-liquid separation device 1, i.e., on the liquid side plate 20 and the gas side plate 30, may be used in pairs, or only one of them may be used.

[0013] The pair of supply and discharge pipes 41a and the pair of supply and discharge pipes 41b are each connected to a fluid flow path 400 (see FIG. 5) described later, and supply and discharge the multiphase fluid into and from the inside of the device. These are used, for example, by being connected to a pump (not shown) that supplies the multiphase fluid. In this embodiment, the multiphase fluid is supplied from both the supply and discharge pipes 41a and 41b, and gas-liquid separation is performed inside the device. When the multiphase fluid is supplied into the device only from the supply and discharge pipe 41a, the multiphase fluid may be discharged from the supply and discharge pipe 41b and circulated, or vice versa. The multiphase fluid may be supplied from one of the supply and discharge pipes 41a and 41b, and the other may be blocked.

[0014] The pair of liquid discharge pipes 21 each communicate with a liquid flow path 200 (see FIG. 5) in the gas-liquid separation device 1, which will be described later, and discharge the liquid separated from the multiphase fluid to the outside of the device. The pair of gas discharge pipes 31 each communicate with a gas flow path 300 (see FIG. 5) in the gas-liquid separation device 1, which will be described later, and discharge the gas separated from the multiphase fluid to the outside of the device. The discharged liquid and gas are each collected in a container or the like provided outside the gas-liquid separation device 1.

[0015] (Internal configuration of gas-liquid separation device 1) The internal configuration of the flow paths and the like formed in the gas-liquid separation device 1 will be described in detail below with reference to Fig. 5. Fig. 5 is a schematic diagram for explaining the internal configuration and fluid flow of the gas-liquid separation device according to this embodiment. In the following description, the direction on the front side of the gas-liquid separation device 1 will be referred to as the front, and the direction on the back side will be referred to as the rear.

[0016] 5, a pair of partition walls 401a, 401b formed in a disk shape and parallel to each other and spaced apart from each other are provided in the gas-liquid mixing plate 40. A fluid flow path 400 is defined between the pair of partition walls 401a, 401b. The pair of partition walls 401a, 401b are provided with a plurality of through holes (not shown) through which the multiphase fluid passes. Between the partition wall 401a and the liquid side plate 20, and between the partition wall 401b and the gas side plate 30, inflow chambers 402, 403 into which the multiphase fluid can flow from the through holes are defined, respectively.

[0017] The inflow chamber 402, at its front side, contacts one surface of a disk-shaped hydrophilic membrane 52 fixed by a separator or the like (not shown) provided between the liquid side plate 20 and the gas-liquid mixing plate 40. Therefore, the inflow chamber 402 functions as a supply path for supplying the multiphase fluid to the hydrophilic membrane 52 together with the fluid flow path 400.

[0018] The hydrophilic membrane 52 is a porous thin film made of a highly hydrophilic material, which forms one wall surface of the inflow chamber 402, thereby forming a hydrophilic partition wall for the multiphase fluid. For this reason, in this embodiment, the hydrophilic membrane 52 is permeable (permeates) only the liquid in the multiphase fluid in a wet state. As the hydrophilic membrane 52 that allows only the liquid to permeate, a known material can be used.

[0019] A liquid flow path 200 is formed in the liquid side plate 20 on the front side of the hydrophilic membrane 52, through which the liquid that has permeated the hydrophilic membrane 52, i.e., the liquid in which gas has been separated from the multiphase fluid, flows and through which the liquid is discharged to the outside. In other words, the hydrophilic membrane 52 forms one wall surface of the liquid flow path 200.

[0020] The inflow chamber 403, at its rear side, contacts one surface of a disk-sheet-shaped hydrophobic membrane 53 fixed by a separator (not shown) or the like provided between the gas side plate 30 and the gas-liquid mixing plate 40. Therefore, the inflow chamber 403 functions as a supply path for supplying the multiphase fluid to the hydrophobic membrane 53 together with the fluid flow path 400.

[0021] The hydrophobic membrane 53 is a porous thin film having gas permeability, which forms one wall surface of the inflow chamber 403 and thereby forms a hydrophobic partition wall portion for the multiphase fluid. For this reason, in this embodiment, the hydrophobic membrane 53 does not permeate the liquid in the multiphase fluid, but only the gas permeates. As such a hydrophobic membrane 53, a known membrane can be used. For example, Gore-Tex (registered trademark) made by WL Gore & Associates, Inc., which is made of ePTFE (expanded polytetrafluoroethylene), can be used. The hydrophobic membrane 53 can be used by appropriately selecting the type according to the usage environment, and may be either an organic membrane or an inorganic membrane. Examples of inorganic membranes include ceramic membranes such as zeolite membranes, silica membranes, alumina membranes, zirconia membranes, and titania membranes, and carbon membranes. Examples of organic membranes include fluororesin membranes such as PTFE (polytetrafluoroethylene) membranes and PVDF (polyvinylidene fluoride) membranes, polymer membranes such as polyamide membranes, cellulose acetate membranes, polyimide membranes, and polyethylene membranes. The porous material may be made water repellent and used as a hydrophobic membrane.

[0022] A gas flow path 300 is formed within the gas side plate 30 on the rear side of the hydrophobic membrane 53, through which gas that has permeated the hydrophobic membrane 53, i.e., gas in which liquid has been separated from the multiphase fluid, flows and through which the gas is discharged to the outside.

[0023] The hydrophilic film 52 and the hydrophobic film 53 are formed in a sheet shape and are provided so as to face each other and be spaced apart. It is preferable that the distance between them is equal to or less than a predetermined distance. The distance is based on the size of bubbles contained in the multiphase fluid. By setting the distance to be equal to or less than the size of the bubbles, the gas bubbles contained in the multiphase fluid can contact both the hydrophilic film 52 and the hydrophobic film 53, and the gas can be quickly transmitted to the gas flow path 300. It is preferable that such a distance is about 1 mm, which allows the multiphase fluid and the bubbles to contact the hydrophobic film 53, respectively. Therefore, the fluid flow path 400 may be formed by the hydrophilic film 52 and the hydrophobic film 53, excluding the above-mentioned partition walls 401a and 401b. That is, the front side wall surface forming the fluid flow path 400 is the hydrophilic film 52, and the rear side wall surface is the hydrophobic film 53. In addition, when the multiphase fluid is mainly composed of gas and droplets such as water droplets are mixed, it is preferable that the distance is based on the size of the droplets contained in the multiphase fluid. By setting the separation distance to be equal to or less than the droplet size, the droplets contained in the multiphase fluid can come into contact with both the hydrophilic membrane 52 and the hydrophobic membrane 53, allowing the liquid to quickly permeate into the liquid flow path 200.

[0024] Moreover, it is preferable that the pore size and the number of pores per unit area of ​​the hydrophilic membrane 52 and the hydrophobic membrane 53 are appropriately set depending on the types of gas and liquid to be separated and the supply pressure of the multiphase fluid.

[0025] (device operation) The operation of the gas-liquid separation device 1 according to this embodiment will be described below. Here, a case where a multiphase fluid is supplied to each of the pair of supply and discharge pipes 41a and 41b will be illustrated. First, when the multiphase fluid is supplied to the pair of supply and discharge pipes 41a and 41b, the multiphase fluid flows into the fluid flow path 400 communicating with the supply and discharge pipe 41a. The hatched arrows indicated by the symbol F1 in FIG. 5 indicate the flow direction of the multiphase fluid. The multiphase fluid that flows into the fluid flow path 400 flows into the inflow chambers 402 and 403 through the through holes of the partition walls 401a and 401b. The multiphase fluid that flows into the inflow chambers 402 and 403 comes into contact with the hydrophilic membrane 52 and also comes into contact with the hydrophobic membrane 53. At this time, the multiphase fluid flows into each membrane surface from the fluid flow path 400 approximately perpendicular to the surface, and the multiphase fluid comes into contact with each membrane surface uniformly. In particular, when the hydrophilic film 52 has dry areas and wet areas, there is a possibility that gas may escape from the dry areas, so it is preferable that the multiphase fluid contacts the surface uniformly.

[0026] When the multiphase fluid comes into contact with the hydrophilic membrane 52, the liquid in the multiphase fluid permeates the hydrophilic membrane 52 and flows into the liquid flow path 200. The hatched arrows indicated by the symbol L in Fig. 5 indicate the flow direction of the liquid permeating the hydrophilic membrane 52. The liquid that has flowed into the liquid flow path 200 is discharged to the outside of the device through a pair of liquid discharge pipes 21 that communicate with the liquid flow path 200.

[0027] Furthermore, when the multiphase fluid comes into contact with the hydrophobic membrane 53, the gas in the multiphase fluid permeates the hydrophobic membrane 53 and flows into the gas flow path 300. The hatched arrows indicated by the symbol G in Fig. 5 indicate the flow direction of the gas permeating the hydrophobic membrane 53. The gas that has flowed into the gas flow path 300 is discharged to the outside of the device through a pair of gas exhaust pipes 31 that communicate with the gas flow path 300.

[0028] According to the embodiment described above, the gas-liquid separation function can be achieved by using only the hydrophilic membrane 52 and the hydrophobic membrane 53 for gas-liquid separation, which satisfactorily separates the liquid and the gas in the multiphase fluid. Therefore, the device configuration is extremely simple, and the device size can be reduced compared to the conventional device. In particular, the sheet-like hydrophilic membrane 52 and the hydrophobic membrane 53 are arranged so as to sandwich the fluid flow path 400, the liquid flow path 200 is formed adjacent to the hydrophilic membrane 52, and the gas flow path 300 is formed adjacent to the hydrophobic membrane 53. Therefore, the gas-liquid separation device 1 can be formed in a flat plate shape as shown in FIG. 1, and can be installed in a small space such as a gap between an apparatus or a structure, and is easy to transport. Since such a small gas-liquid separation device 1 also functions in a microgravity field, it is extremely useful in an environment such as a space station where a gas-liquid separation device is essential but the installation space is limited. In addition, since the configuration is simple, it is easy to maintain and can achieve low costs. Furthermore, since it is only necessary to connect a pump or the like to each tube when using it, it is easy to work with.

[0029] In the present embodiment, the multiphase fluid to be subjected to gas-liquid separation has been described as a gas-liquid two-phase fluid, but this is not limited thereto. Gas-liquid separation can be performed on multiphase fluids with more phases as long as the fluid contains gas.

[0030] Second embodiment The gas-liquid separator according to the first embodiment may be incorporated into a water electrolysis apparatus that generates hydrogen gas and oxygen gas by electrolyzing water. In this embodiment, a water electrolysis apparatus integrated with a gas-liquid separator will be described.

[0031] The configuration of the water electrolysis device according to the present embodiment will be described. FIG. 6 is a perspective view of the water electrolysis device according to the present embodiment. As shown in FIG. 6, the water electrolysis device 1A according to the present embodiment is a cell-stack type device including a plurality of electrolysis cells 10A fastened to each other by bolts and nuts, and a plurality of heat radiation pipes (heat radiation parts) 12A inserted between the electrolysis cells 10A. The heat radiation pipes 12A are so-called heat pipes in which a heat exchange medium flows and exchanges heat with the outside, and by being inserted between the electrolysis cells 10A, the heat radiation of the electrolysis cells in contact therewith can be promoted. The number of inserted heat radiation pipes 12A may be appropriately set depending on the scale of the device. In the present embodiment, three electrolysis cells 10A are connected, but the present invention is not limited thereto, and two or four or more may be connected.

[0032] The water electrolysis apparatus 1A according to this embodiment electrolyzes water into oxygen gas and hydrogen gas using multiple electrolysis cells 10A, and the electrolysis cells 10A have the same device configuration and operation. Therefore, hereinafter, the device configuration and operation of one electrolysis cell 10A will be described.

[0033] First, the configuration of the electrolysis cell 10A will be described in detail below. For the sake of explanation, a unit electrolysis cell having end plates 60, 70 provided on the front and back sides will be described as an example. Figs. 7 to 10 are a perspective view, a front view, a right side view, and a left side view, respectively, showing an electrolysis cell according to this embodiment. As shown in Fig. 7, the electrolysis cell 10A includes an end plate 60, an intermediate plate 61, an end plate 70, an intermediate plate 71, and current collector plates 81a, 81b.

[0034] The end plates 60, 70 are formed in a square flat plate shape and constitute the front wall and rear wall of the electrolytic cell 10A. The intermediate plate 61, current collector plates 81a, 81b, and intermediate plate 71 are disposed between the end plates 60, 70, and the end plates 60, 70 are fastened with bolts and nuts to integrally form the electrolytic cell 10A in a substantially rectangular parallelepiped shape. When stacking multiple electrolytic cells 10A as shown in FIG. 7, multiple electrolytic cells each consisting of intermediate plates 61, 71 may be interposed between a pair of end plates 60, 70.

[0035] The intermediate plates 61, 71 are formed to have the same shape and thickness as the end plates 60, 70. A water supply pipe 611, a drain pipe 612, and two hydrogen discharge pipes 613 are provided on the side of the intermediate plate 61. A water supply channel 614, a drain channel 615, and a hydrogen discharge channel 616 (see FIG. 12) are provided inside the intermediate plate 61, which will be described in detail later. The water supply pipe 611 is located on the lower left side in FIG. 8 and communicates with the water supply channel 614, and supplies water to the electrolysis cell 10A. The drain pipe 612 is located on the upper right side in FIG. 8 and communicates with the drain channel 615, and discharges water from the electrolysis cell 10A for circulating and supplying it. The two hydrogen discharge pipes 613 are located on the lower right side and upper left side in FIG. 8, respectively, and communicate with the hydrogen discharge channel 616. The two hydrogen exhaust pipes 613 exhaust the hydrogen gas generated by electrolysis in the electrolysis cell 10A to the outside of the electrolysis cell 10A.

[0036] 9 and 10, oxygen exhaust pipes 711 are provided on the lower right side and the upper left side of the intermediate plate 71. The oxygen exhaust pipes 711 communicate with an oxygen exhaust passage 712 (see FIG. 12), which will be described in detail later, and exhaust oxygen gas generated by electrolysis in the electrolysis cell 10A to the outside of the electrolysis cell 10A.

[0037] The internal configuration of the electrolysis cell 10A will be described in detail below with reference to Fig. 11. Fig. 11 is an exploded side view showing the configuration of an electrolysis cell according to this embodiment. In Fig. 11, the electrolysis cell 10A is shown exploded in the front-rear direction, and for the sake of explanation, the O-rings 62, 72 and the gaskets 65, 82 are shown partially in cross section.

[0038] 11, the electrolysis cell 10A includes, in order from the left side in Fig. 11, i.e., the front side of the cell, an end plate 60, an intermediate plate 61, an O-ring 62, a separation separator 63, carbon paper 64, a gasket 65, a hydrophobic membrane 53, a gasket 65, carbon paper 64, a current collector 81a, a gasket 82, an MEA (Membrane and Electrode Assembly) 80, a current collector 81b, an O-ring 72, an intermediate plate 71, and an end plate 70. The left side of the MEA 80 in Fig. 11 is the hydrogen side where water is supplied and hydrogen gas is produced, and the right side of the MEA 80 in Fig. 11 is the oxygen side where oxygen gas is produced.

[0039] The MEA 80 is a roughly rectangular plate-shaped member formed by sandwiching a solid polymer electrolyte membrane (hereinafter referred to as the electrolyte membrane) between gas diffusion electrode layers from the front and rear, with one side on the hydrogen side and the other on the oxygen side, and then bonding these together. + It is preferable to use a porous electrolyte membrane having a proton conductivity, such as inorganic ceramics containing titanium hydroxide nanoparticles or proton-conducting Nafion (registered trademark).

[0040] The gas diffusion electrode layer is porous, and hydrogen gas and oxygen gas can pass through it. For example, Teflon (registered trademark) modified porous carbon can be used as the material of such a diffusion layer. A catalyst layer of platinum, gold, or the like is provided between the gas diffusion electrode layer and the electrolyte membrane. In this embodiment, the catalyst layer is formed on the electrolyte membrane. The electrolysis cell 10A according to this embodiment is a cathode feed type in which water is supplied only to the cathode side to perform electrolysis, and the water supplied to the cathode side permeates the electrolyte membrane and also permeates the anode side. The gas diffusion electrode layer on the cathode side and the current collector plate 81a constitute the cathode side electrode part, and the gas diffusion electrode layer on the anode side and the current collector plate 81b constitute the anode side electrode part.

[0041] The MEA 80 is sandwiched or fixed between the current collector plates 81a and 81b via frame-shaped gaskets 82 located on both sides of the MEA 80 and connected to its edges. The current collector plates 81a and 81b are plate-shaped members that are electrically connected to an external power source to apply a voltage to the MEA 80, and in FIG. 8, a connection piece for connecting to the external power source protrudes upward. In this embodiment, the current collector plates 81a and 81b are configured integrally with the separator. A plurality of grooves are formed in the separator of the current collector plate 81a so as to penetrate therethrough, and in a state in which the electrolysis cell 10A is assembled, a water flow path 811 (see FIG. 12) into which water flows is formed by these plurality of grooves. The water flow path 811 functions as a liquid supply chamber in which the cathode side electrode part is located and into which liquid is supplied, and the water is supplied to the MEA 80. It is preferable that the water flow path 811 is formed so that the water supplied to the MEA 80 is supplied to the entire membrane surface of the electrolyte membrane. The water flow path 811 communicates with the water supply pipe 611 via a water supply passage 614 formed in the intermediate plate 61 , and communicates with the drain pipe 612 via a drain passage 615 .

[0042] Meanwhile, a plurality of grooves are also formed in the separator of the current collector plate 81b, and these grooves form oxygen flow paths 713 (see FIG. 12) into which oxygen gas generated by electrolysis flows when the electrolysis cell 10A is assembled. The oxygen flow paths 713 are connected to oxygen exhaust paths 712 formed in the adjacent intermediate plate 71, and communicate with the oxygen exhaust pipe 711 via the oxygen exhaust paths 712. The O-ring 72 is an elastic member, and the separator of the current collector plate 81b and the intermediate plate 71 are connected airtightly via the O-ring 72.

[0043] A rectangular hydrophobic membrane 53 is disposed on the front side of the current collector plate 81a. The hydrophobic membrane 53 is disposed so as to face and be spaced apart from the MEA 80, and forms a partition wall of a part of the liquid supply chamber formed by the water flow path 811. This hydrophobic membrane 53 is the same as that described in the first embodiment, so the description of its function will be omitted here. The hydrophobic membrane 53 is fixed to the current collector plate 81a and the separator via a frame-shaped gasket 65 located on both sides and connecting with the edges. Carbon paper 64 having gas permeability for the diffusion of gas and water is disposed between the hydrophobic membrane 53 and the current collector plate 81a, and the hydrophobic membrane 53 can come into contact with water and hydrogen gas that becomes a bubble state in the water through the carbon paper 64.

[0044] It is preferable that the distance between the hydrophobic membrane 53 and the electrolyte membrane of the MEA 80, more specifically, the distance from the cathode side catalyst layer, is the distance described in the first embodiment. This allows the hydrogen gas bubbles generated and attached to the catalyst layer surface to come into contact with the hydrophobic membrane 53, allowing them to immediately permeate the hydrophobic membrane 53. As in the first embodiment, this distance is based on the size of the generated gas bubbles, and it is preferable that the bubbles come into contact with the hydrophobic membrane 53 before leaving the catalyst layer. This distance is preferably about 1 mm, for example, which allows water and bubbles to come into contact with the hydrophobic membrane 53.

[0045] The separation separator 63 located in front of the hydrophobic membrane 53 is provided with a plurality of grooves forming a hydrogen flow path 631 (see FIG. 12) into which hydrogen gas that has permeated the hydrophobic membrane 53 flows. The hydrogen flow path 631 of the separation separator 63 is connected to a hydrogen discharge path 616 formed in the adjacent intermediate plate 61 via an O-ring 62, and communicates with a hydrogen discharge pipe 613 via the O-ring 62. The separation separator 63 is also formed with a groove separate from the groove forming the hydrogen flow path 631, and the groove serves as a water flow path connecting a water flow path 811 in the separator of the current collector plate 81a to a water supply path 614 formed in the intermediate plate 61. The O-ring 62 is an elastic member, and the separation separator 63 and the intermediate plate 61 are connected airtightly via the O-ring 62.

[0046] (device operation) The operation of the electrolysis cell 10A according to this embodiment will be described below. FIG. 12 is a schematic diagram for explaining the internal configuration and fluid flow of the electrolysis cell according to this embodiment. The two-dot chain lines in the figure illustrate the joints of each flow path. Symbol P1 indicates a pump, symbol H1 indicates the flow direction of hydrogen gas, symbol H2 indicates hydrogen gas bubbles, and symbol O1 indicates the flow direction of oxygen gas, respectively. The pump P1 is connected to a water supply pipe 611 and a drain pipe 612, and supplies water to the water supply pipe 611 and obtains water from the drain pipe 612, and circulates the water to the electrolysis cell 10A. Note that the electrolysis cell 10A is constantly supplied with water used for electrolysis from an external water supply device.

[0047] As shown in Fig. 12, water supplied through a water supply pipe 611 flows into a water flow path 811 through a water supply channel 614, and the water that has flowed into the water flow path 811 is supplied to the entire membrane surface of the electrolyte membrane 800 in the MEA 80. Here, water is electrolyzed by applying a voltage to current collectors 81a and 81b connected to an external power source. Hydrogen gas generated by the electrolysis at the interface between the cathode-side gas diffusion electrode layer 801 and the electrolyte membrane 800 of the MEA 80, i.e., the catalyst layer, contacts and permeates the hydrophobic membrane 53 in the water flow path 811, and flows into the hydrogen flow path 631. Specifically, the generated hydrogen gas permeates while being diffused inside the gas diffusion electrode layer, passes through the separator and carbon paper 64 of the current collector 81a, and contacts the hydrophobic membrane 53. The hydrogen gas in the hydrogen flow channel 631 that has permeated the hydrophobic membrane 53 is discharged from the hydrogen discharge pipe 613 via the hydrogen discharge channel 616 to the outside of the electrolysis cell 10A and collected in a collection container or the like.

[0048] Meanwhile, water in the water flow path 811 that has not been used for electrolysis is discharged from the drain pipe 612 via the drain channel 615 to the pump P1 and is then supplied again into the electrolysis cell 10A. Hydrogen gas produced by electrolysis at the interface between the anode side gas diffusion electrode layer 802 of the MEA 80 and the electrolyte membrane 800 flows into the oxygen flow path 713 and is discharged from the oxygen discharge pipe 711 via the oxygen discharge channel 712 to the outside of the electrolysis cell 10A and is collected in a collection container or the like.

[0049] According to the water electrolysis device 1A of the present embodiment described above, since the hydrophobic membrane 53 is disposed in the water flow path 811 which is the cathode chamber on the cathode side, water circulates through the water flow path 811 between the hydrophobic membrane 53 and the MEA 80, and reliable gas-liquid separation can be performed simultaneously with electrolysis. In particular, hydrogen gas can be recovered in a good dry state. Therefore, the electrolysis cell can have the function of a gas-liquid separator, and there is no need to prepare a separate gas-liquid separator, so the device can be significantly smaller than a water electrolysis device connected to a gas-liquid separator separately. In addition, it can be installed in a small space such as a gap between an apparatus or a structure, and is easy to transport. Such a small water electrolysis device 1A functions even in a microgravity field, and is therefore extremely useful in an environment such as a space station where a water electrolysis device is essential but the installation space is limited.

[0050] In addition, when water is supplied to the cathode side, a gas phase exists in the water tank on the ground and absorbs the pressure, but when water electrolysis is performed in a microgravity environment, it is necessary to circulate a non-compressible fluid such as water in a sealed container without a gas phase. When water electrolysis is performed in a sealed space, the gas generated in the electrolysis cell increases the pressure inside the electrolysis cell, causing the balance of pressure between the oxygen side and the hydrogen side to be lost. If this is left unattended, one-sided pressure will be applied to the electrolyte membrane, which may damage the membrane. Therefore, in the past, a volume buffer device such as an accumulator was required. However, according to this embodiment, the hydrogen gas generated in the MEA 80 is immediately discharged through the hydrophobic membrane 53, so volume buffering is performed, and it is impossible for only one side to be pressurized in response to the generation of gas. Therefore, there is no need to use a volume buffer device, which allows for low cost and miniaturization. In addition, since water is supplied only to the cathode side, the pump P1 is reduced to one unit, which also allows for low cost and miniaturization.

[0051] In addition, in the past, there was a method of permeating water from the periphery to the center of the electrolyte membrane of the MEA, but in this method, the water path and the reaction path are independent, so the effective membrane area of ​​the electrode becomes smaller. Furthermore, since the interface is maintained by surface tension, if the balance between the pressure on the liquid side and the pressure on the gas side is lost, there is a possibility that the liquid will leak to the gas side or the gas will invade the liquid. However, in this embodiment, the water supplied to the MEA 80 is supplied to the entire membrane surface of the electrolyte membrane 800, so the distance that the water permeates can be limited to the membrane thickness only. As a result, a water supply path that is smooth and has a high degree of freedom can be secured, so that the water can be easily circulated.

[0052] The electrolysis cell 10A can have an air regeneration function by connecting it to a Sabatier reactor, which produces methane (CH4) and water (H2O) from carbon dioxide (CO2) and oxygen (O2). Air regeneration is a process in which O2 is extracted again from the CO2 emitted by astronauts. Specifically, CO2 emitted into an enclosed space by living organisms is separated and concentrated, and then led to the Sabatier reactor. In the Sabatier reactor, the Sabatier reaction (CO2 + 4H2 → CH4 + 2H2O) takes place, producing CH4 and H2O.

[0053] The electrolysis cell 10A generates hydrogen gas and oxygen gas by receiving water generated by the Sabatier reaction from the Sabatier reactor. Organisms breathe oxygen gas, and the hydrogen gas is sent back to the Sabatier reactor. By repeating this cycle, oxygen can be consumed and oxygen can be generated again from carbon dioxide emitted by organisms through breathing, thereby realizing air regeneration.

[0054] Furthermore, in the water electrolysis apparatus 1A, by stacking multiple electrolysis cells 10A, it is possible to increase the amounts of hydrogen gas and oxygen gas produced compared to a single electrolysis cell 10A. In this case, for example, it is preferable to connect the water circulation supply path (the water supply pipe 611 and the drain pipe 612) to the pump P1 to a manifold so that the water circulation supply path is shared by the multiple electrolysis cells 10A, and the same applies to the discharge paths for hydrogen gas and oxygen gas (the hydrogen discharge pipe 613 and the oxygen discharge pipe 711).

[0055] (First Modification) Fig. 13 is a schematic diagram for explaining the internal configuration and fluid flow of the electrolysis cell according to the first modification. In Fig. 13, reference symbol P2 denotes a pump, which is similar to pump P1. Reference symbol O2 denotes oxygen gas bubbles.

[0056] 13 differs from the electrolysis cell 10A according to the second embodiment in that a hydrophobic membrane 53' is also arranged on the anode side, a water flow path 812 is formed between the hydrophobic membrane 53' and the MEA 80 as a second liquid supply chamber to which an anode-side electrode part is arranged and to which water is supplied, and water is circulated and supplied to the water flow path 812 by a pump P2. The hydrophobic membrane 53' is the same as the hydrophobic membrane 53, but differs in that it forms a partition wall of part of the water flow path 812 and allows only oxygen gas generated on the anode side of the electrolyte membrane 800 by electrolysis to pass therethrough.

[0057] Specifically, the electrolysis cell 10B can be constructed by arranging an intermediate plate 61, an O-ring 62, a separator 63, a carbon paper 64, a gasket 65, a hydrophobic membrane 53, a gasket 65, a carbon paper 64, and a current collector 81a in a mirror image arrangement with respect to the MEA 80, instead of the current collector 81b, the O-ring 72, and the intermediate plate 71 shown in Fig. 11. As a result, oxygen gas, rather than hydrogen gas, flows into the flow path for hydrogen gas in each of the components arranged in a mirror image arrangement. That is, in each of the components arranged in a mirror image arrangement, water is circulated and supplied to the anode side, and oxygen gas that has permeated the hydrophobic membrane 53 is discharged.

[0058] By providing the hydrophobic membrane 53' on the anode side in this way, the same effect as on the cathode side can be achieved on the anode side as well, and dried, high-quality oxygen gas can be collected. In addition, water can be supplied from both sides of the MEA 80, which further improves the heat dissipation function of the heat generated inside the cell by electrolysis.

[0059] (Second Modification) Fig. 14 is a schematic diagram illustrating the internal configuration and fluid flow of the electrolysis cell according to the second modification. The electrolysis cell 10C shown in Fig. 14 differs from the electrolysis cell 1A according to the second embodiment in that it does not include a drainage channel 615. Therefore, the electrolysis cell 10C does not have a water circulation function, and is a dead-end type in which all water flowing into the water flow channel 811 is used for water electrolysis.

[0060] The amount of water required to generate oxygen for one person by water electrolysis is small, about 0.5 g per minute. Meanwhile, in conventional water electrolysis, several liters of water are circulated to remove bubbles on the electrodes and to remove heat generation, and a pump for circulating and supplying water, a gas-liquid separator, and power for the above are required. However, with the electrolysis cell 10C according to this modification, by supplying only a small amount of water (e.g., 0.5 g per minute) required for water electrolysis, all of the supplied water can be electrolyzed. Therefore, it is possible to reduce the pump P1 for circulating and supplying water as well as the gas-liquid separator compared to conventional systems, and the system for producing oxygen gas can be significantly simplified, which in turn allows the system to be made smaller, lighter, and more energy-efficient, and further improves the reliability of the system.

[0061] The electrolysis cell 10C can be integrated with the Sabatier reactor described in the first embodiment. Conventional electrolysis cells lower the cell temperature by circulating water, which also lowers the temperature of the Sabatier reactor. On the other hand, the electrolysis cell 10C does not require water circulation, so the reaction can be continued without lowering the temperature of the integrated Sabatier reactor. In addition, a very compact device can be made by stacking the electrolysis cell 10C and the Sabatier reactor. In addition, the heat generated in the Sabatier reactor can also be used to heat the water electrolysis cell, making it possible to lower the electrolysis voltage.

[0062] Furthermore, when water circulation is not performed as in this modified example, heat may accumulate inside the cell. In this case, a heat sink pipe 12A as shown in Fig. 7 may be provided on one of the intermediate plates 61, 71 of the electrolysis cell 10C, or between the electrolysis cells 10C when they are stacked.

[0063] Although an embodiment of the invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and spirit of the invention, and are included in the invention and its equivalents described in the claims. [Explanation of symbols]

[0064] 1 Gas-liquid separator 1A water electrolysis device 10A, 10B, 10C Electrolytic cells 12A heat radiation tube (heat radiation part) 400 Fluid flow path (supply path) 52 Hydrophilic membrane (hydrophilic partition) 53,53' Hydrophobic membrane (hydrophobic partition) 616 Hydrogen exhaust (exhaust) 712 Oxygen exhaust passage (second exhaust passage) 81a, 81b Current collector (cathode electrode part, anode electrode part) 800 Solid polymer electrolyte membrane 801 Cathode side gas diffusion electrode layer (cathode side electrode part) 802 Anode side gas diffusion electrode layer (anode side electrode part) 811,812 Water flow path (liquid supply chamber, 2nd liquid supply chamber)

Claims

1. An electrolysis device that generates gas by electrolyzing a liquid supplied to an electrolyte membrane between an anode electrode section and a cathode electrode section, a liquid supply chamber in which the cathode electrode portion is disposed and to which the liquid is supplied; a hydrophobic membrane which forms a partition wall of a part of the liquid supply chamber and allows only a gas generated on the cathode side of the electrolyte membrane by the electrolysis to pass therethrough; an exhaust path for exhausting the gas that has permeated the hydrophobic membrane to the outside; An electrolysis apparatus comprising:

2. The hydrophobic membrane and the electrolyte membrane are disposed so as to face each other and be spaced apart from each other, and the distance between them is determined based on the size of the gas bubbles.

2. The electrolysis apparatus according to claim 1.

3. By providing the above-mentioned separation distance between the hydrophobic membrane and the electrolyte membrane and bringing them close to each other, the gas bubbles come into contact with the hydrophobic membrane before they leave the cathode electrode portion, and immediately permeate the hydrophobic membrane and are discharged to the outside through the discharge path.

3. The electrolysis apparatus according to claim 2.

4. a second liquid supply chamber in which the anode side electrode unit is disposed and to which the liquid is supplied; a hydrophobic membrane which forms a partition wall of a portion of the second liquid supply chamber and allows only a gas generated on the anode side of the electrolyte membrane by the electrolysis to pass therethrough; a second exhaust path for exhausting the gas that has permeated the hydrophobic membrane to the outside; The electrolysis device according to any one of claims 1 to 3, further comprising:

5. The liquid supplied to the liquid supply chamber is all turned into gas by the electrolysis. The electrolysis device according to any one of claims 1 to 4.

6. A heat dissipation section that dissipates heat generated by the electrolysis to the outside. The electrolysis device according to any one of claims 1 to 5, further comprising:

7. 1. An electrolysis method for generating gas by electrolyzing a liquid supplied to an electrolyte membrane between an anode electrode section and a cathode electrode section, comprising: A liquid is supplied from the cathode electrode portion to the electrolyte membrane, and a gas is generated on the cathode side of the electrolyte membrane by the electrolysis and mixed with the liquid; The gas mixed in the liquid is separated from the liquid by passing it through a hydrophobic membrane through which only gas can pass. Electrolysis method comprising:

Images