JP7315600B2 - Water electrolysis device, water electrolysis method, water electrolysis system, water electrolysis/fuel cell device, water electrolysis/fuel cell operating method, and water electrolysis/fuel cell system - Google Patents

Description

The present invention relates to a water electrolysis apparatus , a water electrolysis method , and a water electrolysis system using solid polymer water electrolysis cells, and a water electrolysis/fuel cell apparatus , water electrolysis/fuel cell operating method , and water electrolysis/fuel cell system using solid polymer water electrolysis fuel cell integrated cells.

Conventionally, a plurality of solid polymer type water electrolysis cells, in which power feeders are arranged on both sides of an electrolyte membrane and separators are arranged on the outside of each cell, are stacked and used as a water electrolysis device (Patent Document 1).

More specifically, the technique of Patent Document 1 aims to distribute the raw water for water electrolysis evenly to the water flow passages to uniformly and reliably supply the raw water to the entire water flow passages to perform water electrolysis treatment. Specifically, a plurality of inlet connecting channels are provided for communicating the water supply communicating holes and the water channels, and the water supply communicating hole is configured so that the inner wall surface of the communicating hole where the plurality of inlet connecting channels open and the outer wall surface of the communicating hole facing the inner wall surface of the communicating hole have an elongated oval opening cross section.

As a result, the raw water is evenly branched from the oval water supply passage to a plurality of inlet connecting passages, and then supplied to the water passage. In the water passage, the water is prevented from preferentially flowing particularly to the central side close to the water supply passage. As a result, the occurrence of variations in pressure loss within the water flow path is suppressed, and water is evenly distributed over the entire water flow path.

JP 2011-127209 A

However, the above-described prior art aims to perform water electrolysis by evenly distributing the raw water for water electrolysis to the water flow passages and supplying the raw water uniformly and reliably to the entire water flow passage, but does not particularly suggest the pressure loss based on the length of each flow passage.

The present invention has been made in view of such a point, and an object of the present invention is to perform a suitable water electrolysis treatment by flowing a large amount of raw water for water electrolysis into the reaction area of the cell while suppressing the power of the pump.

前記目的を達成するため、本発明は、電解質膜の両側に給電体を配置してさらにセパレータを各給電体の外側に配置した固体高分子形の水電解セルを、複数積層した水電解装置であって、前記固体高分子形の水電解セルは長方形であって、かつ当該水電解セルは横長かつ鉛直方向に配置され、かつ水平方向に積層されており、前記長方形の各水電解セルの１の短辺側の端部において、前記水電解セルの長手方向における当該水電解セルの電極部分よりも外側に、水素ガス排出用の連通口が配置され、前記水素ガス排出用の連通口は、前記電極部分の下端よりも低い位置に形成され、前記電極部分の形状は、前記水電解セルの長手方向に流体を流すときの流路圧損に対して前記水電解セルの短手方向に流体を流したときの流路圧損が１／１６以下となるような横長であることを特徴としている。
Furthermore, the communication port for discharging hydrogen gas may be arranged at a corner of the water electrolysis cell.
In the water electrolysis device described above, a communication port for discharging hydrogen gas may be arranged on the short side of each of the rectangular water electrolysis cells.
Furthermore, it is preferable to use a separator in which a flow path through which a fluid can flow is formed both in the vertical direction and in the horizontal direction. As such a separator, known materials such as an embossed plate, mesh, punching metal, etc. can be used as its constituent material.

According to the present invention, the solid polymer type water electrolysis cell is rectangular, and the water electrolysis cells are arranged horizontally and vertically, and these cells are stacked horizontally. For example, when raw water is supplied into the water electrolysis cell from the lower long side to the upper long side of the water electrolysis cell, the flow path length is in the short side direction, for example, considering the same reaction area. I can. Since the length of the flow path is in the short side direction, the reaction flow path is shortened, and the pressure loss can be kept low. Therefore, it is possible to supply a large amount of raw water to the reaction area of the cell while suppressing the power of the pump that supplies the raw water.

According to another aspect of the present invention, there is provided a method for electrolyzing water using the above-described water electrolysis apparatus, wherein raw water is supplied into the water electrolysis cell from the lower long side of the rectangular water electrolysis cell toward the upper long side .

According to still another aspect, the present invention is a water electrolysis system using the water electrolysis device described above , characterized by comprising: a power supply device for supplying DC power to the water electrolysis device (directly, to power feeders on both sides of the electrolyte membrane); a raw water supply channel for supplying raw material water to the water electrolysis device; a hydrogen gas release channel for releasing hydrogen gas generated in the water electrolysis device to the outside of the system;

Furthermore, in view of the characteristics of the water electrolysis cell employed in the water electrolysis method, the water electrolysis device, and the water electrolysis system, the following invention can be proposed.

まず、電解質膜の両側に給・集電体を配置してさらにセパレータを各給・集電体の外側に配置した、固体高分子形の水電解燃料電池一体型セルを、複数積層した水電解・燃料電池装置であって、前記固体高分子形の水電解燃料電池一体型セルは長方形であって、かつ当該水電解燃料電池一体型セルは横長かつ鉛直方向に配置され、かつ水平方向に積層されており、前記長方形の各水電解燃料電池一体型セルの下側の長辺側に、水電解運転の際の原料水供給のための連通口、及び冷却水供給のための連通口が配置され、各水電解燃料電池一体型セルの上側の長辺側に、水電解運転の際の電解水と酸素ガスの排出用の連通口が配置され、各水電解燃料電池一体型セルの短辺側に、水電解運転の際の水素ガス排出用の連通口、及び燃料電池運転の際の水素ガス供給用の連通口、及び空気または酸素ガス供給用の連通口が形成され、前記水電解燃料電池一体型セルの電極部分の形状は、縦横比が１：２以上の横長または前記水電解燃料電池一体型セルの長手方向に流体を流すときの流路圧損に対して前記水電解燃料電池一体型セルの短手方向に流体を流したときの流路圧損が１／１６以下となるような横長であることを特徴とする、水電解・燃料電池装置。
Further , the communication port for discharging hydrogen gas may be arranged at a corner portion of the water electrolysis fuel cell integrated cell.
Further, it is preferable to use a separator having a flow path through which a fluid can flow both in the vertical direction and in the horizontal direction. For this separator, a known separator such as an embossed plate, mesh, punching metal, etc., as described above, can be used.
Furthermore, in such a water electrolysis/fuel cell device, a communication port for discharging air or oxygen gas and reaction product water may be formed on the short side of the water electrolysis fuel cell integrated cell, and the lowermost portion of the communication port for discharging air or oxygen gas and reaction product water may be positioned lower than the lowest portion of the electrode surface of the water electrolysis fuel cell integrated cell.

According to another aspect, a method of switching between water electrolysis operation and fuel cell operation using the water electrolysis/fuel cell device described above, wherein during water electrolysis operation, raw water is supplied into the water electrolysis fuel cell integrated cell from the lower long side of the rectangular water electrolysis fuel cell integrated cell toward the upper long side, and during fuel cell operation, the raw material gas is supplied into the water electrolysis fuel cell integrated cell from the short side toward the opposite short side of the rectangular water electrolysis fuel cell integrated cell. A water electrolysis/fuel cell operation method characterized by the following can be proposed.

As a water electrolysis/fuel cell system using the above water electrolysis/fuel cell device, for example, the following can be proposed. a source water supply path for supplying raw material water to the water electrolysis/fuel cell apparatus; a hydrogen gas release path for releasing hydrogen gas generated in the water electrolysis/fuel cell apparatus to the outside of the system; an oxygen gas release path for releasing oxygen gas generated in the water electrolysis/fuel cell apparatus to the outside of the system; a hydrogen gas supply path for supplying hydrogen gas to the water electrolysis/fuel cell apparatus; and an oxygen gas discharge path for discharging water generated in the water electrolysis/fuel cell device to the outside of the system.

According to the present invention, it is possible to supply a large amount of raw material water to the reaction area of the cell while suppressing the power of the pump that supplies the raw material water, and it is possible to perform suitable water electrolysis treatment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing an outline of a system of a water electrolysis system incorporating a water electrolysis cell stack according to an embodiment; 1 is an exploded perspective view of a water electrolysis cell used in a water electrolysis cell stack according to an embodiment; FIG. FIG. 4 is a front view of the oxygen electrode side separator showing how fluid flows on the oxygen electrode side separator in the water electrolysis cell stack according to the embodiment. FIG. 4 is a front view of the hydrogen electrode side separator showing how fluid flows on the hydrogen electrode side separator in the water electrolysis cell stack according to the embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing an outline of a system of a water electrolysis/fuel cell system incorporating a stack of water electrolysis/fuel cell cells according to an embodiment; FIG. 4 is an exploded perspective view showing how fluid flows during water electrolysis operation in the solid polymer integrated cell used in the water electrolysis/fuel cell stack according to the embodiment. FIG. 2 is an exploded perspective view showing how fluid flows during operation of the fuel cell in the solid polymer integrated cell used in the water electrolysis/fuel cell stack according to the embodiment. 4 is a graph showing the ratio of channel pressure loss to the aspect ratio of electrodes. FIG. 10 is an explanatory view from the front side showing a state in which a communication port for discharging air and reaction-generated water is positioned below the lowermost portion of the electrode surface and the lowermost portion of the sealing material in the separator of the solid polymer integrated cell.

FIG. 1 shows an outline of the configuration of a water electrolysis system 1 according to an embodiment of the present invention. This water electrolysis system 1 has a water electrolysis cell stack 13 as a water electrolysis device, which is constructed by connecting and stacking a plurality of solid polymer water electrolysis cells (unit cells) 10 shown in FIG.

As shown in FIG. 2, the water electrolysis cell 10 has an electrode body 21 having a structure in which an electrolyte membrane is sandwiched between current collectors from both sides, and a hydrogen electrode side separator 31 and an oxygen electrode side separator 41 that sandwich the electrode body 21 from both sides.

The electrode body 21, the separator 31 on the hydrogen electrode side, and the separator 41 on the oxygen electrode side have an electrode portion 22 and regions 32 and 42 corresponding to the electrode portion 22 in the center, respectively. Communicating holes 23 , 24 , 33 , 34 , 43 , 44 are formed above and below the electrode portion 22 and regions 32 , 42 . These communication ports 23, 24, 33, 34, 43, 44 function as manifolds for electrolyzed water and oxygen gas generated by water electrolysis. The horizontal lengths of the communication ports 23 , 24 , 33 , 34 , 43 , 44 are set to the same lengths as the electrode portion 22 and the regions 32 , 42 .

In the electrode body 21, the hydrogen electrode side separator 31, and the oxygen electrode side separator 41, respectively, vertically long communication ports 25, 35, and 45 functioning as manifolds for hydrogen gas generated during water electrolysis are formed in one side lower side (lower right side in FIG. 2 in this embodiment) of the central electrode portion 22 and regions 32 and 42 corresponding to the electrode portion 22, respectively.

As for the separator 31 on the hydrogen electrode side, sealing materials 36 and 37 (indicated by dashed lines) are arranged around the back surface of the communication ports 33 and 34 so as to independently surround the communication ports 33 and 34, respectively. A sealing material 38 (indicated by broken lines) is arranged so as to surround the rear surface of the central region 32 and the rear surface of the communication port 35 together. Regarding the separator 41 on the oxygen electrode side, a sealing material 46 is arranged so as to surround the central region 42 and the communication ports 43 and 44 together, and a sealing material 47 is provided around the communication port 45 so as to independently surround only the communication port 45. These sealing materials 36 to 38, 46, and 47 prevent each fluid from flowing out of paths other than predetermined paths.

In this embodiment, at least the central regions 32 and 42 of the separator 31 on the side of the hydrogen electrode and the separator 41 on the side of the oxygen electrode are made of a material such as an embossed plate, mesh, or punching metal, which forms a large number of irregularities on the surface, unlike the material that constitutes a general straight channel or serpentine channel. As a result, the separator 31 on the hydrogen electrode side and the separator 41 on the oxygen electrode side are provided with channels through which fluid can flow both in the vertical direction and the horizontal direction.

As described above, a plurality of water electrolysis cells (unit cells) 10 having the above configuration are vertically erected, and as shown in FIG.

Next, returning to FIG. 1, the water electrolysis system 1 employing this water electrolysis cell stack 13 will be described. A pure water inlet port P<b>1 of the water electrolysis cell stack 13 is supplied with, for example, pure water as raw material water. Specifically, raw water (pure water) is supplied from a tank 51 having a gas-liquid separation function on the oxygen side to the pure water inlet port P1 serving as the raw water inlet of the water electrolysis cell stack 13, and water electrolysis is performed.

More specifically, a pipe 52 is connected between the bottom of the tank 51 and the pure water inlet port P1 of the water electrolysis cell stack 13 . Pure water as raw water is supplied from the tank 51 to the pure water inlet port P1 of the water electrolysis cell stack 13 by a pump 53 provided in the pipe 52 . The pipe 52 is provided with a check valve 54 downstream of the pump 53 , and further downstream with a pressure gauge 55 for measuring the pressure inside the pipe 52 . The pure water inlet port P1 communicates with the communication ports 24, 34, 44 shown in FIG.

A return pipe 56 for returning part of the water flowing in the pipe 52 to the tank 51 is connected to the pipe 52 on the downstream side of the pump 53. The return pipe 56 is provided with a flow control valve V1, a heat exchanger 57, an ion exchange resin tower 58, and a filter 59. By treating the return water through these devices, the quality of the water in the tank 51 is maintained. The tank 51 is provided with a liquid level sensor 51a for detecting the water level in the tank. The tank 51 is replenished with pure water as raw material water through a pipe 60 from an external pure water supply source (not shown) based on a signal from the liquid level sensor 51a. Oxygen gas remaining in the air layer inside the tank 51 is discharged to the outside or to an external demand destination through the pipe 63 .

The raw water supplied from the pure water inlet port P1 to the water electrolysis cell stack 13 through the pipe 52 is electrolyzed in the water electrolysis cell stack 13, and oxygen and the water accompanying the oxygen are returned to the tank 51 from the pure water outlet port P2, which is the outlet on the oxygen side, through the pipe 61 and gas-liquid separated in the tank 51. The pipe 61 is provided with a pressure gauge 62 for measuring the pressure inside the pipe 61 and an electromagnetic valve V2. The pure water outlet port P2 communicates with the communication ports 23, 33, 43 shown in FIG.

A hydrogen outlet port P3 serving as a hydrogen side outlet of the water electrolysis cell stack 13 is connected to a pipe 71, and this pipe 71 communicates with a tank 72 having a gas-liquid separation function on the hydrogen side. The hydrogen outlet port P3 communicates with the communication ports 25, 35 and 45 shown in FIG.

A pipe 73 is connected between the tank 72 and the air layer portion of the tank 51 (the portion above the liquid level of the water stored in the tank, and the portion where the liquid level does not reach even if the stored liquid level rises). The pipe 73 is provided with an electromagnetic valve V3 and a valve V4. A liquid level sensor 72a is provided in the tank 72 to detect the water level in the tank.

As described above, the hydrogen generated by water electrolysis is sent to the tank 72 through the pipe 71 together with the accompanying water, and gas-liquid separation is performed in the tank 72 . The hydrogen gas after gas-liquid separation in the tank 72 is sent through a pipe 74 to, for example, a demand side or a hydrogen storage tank (high-pressure container, not shown). A back pressure valve V5 is provided in the pipe 74, and a discharge pipe 75 is connected to the upstream side of the back pressure valve V5 in the pipe 74. The discharge pipe 75 is provided with an electromagnetic valve V6.

A DC power supply 2 is connected to the water electrolysis cell stack 13, and the pure water for electrolysis supplied from the pure water inlet port P1 is electrolyzed into hydrogen ions and oxygen ions in accordance with the output thereof. Among them, oxygen ions become oxygen molecules on the catalyst in the water electrolysis cell 10 and are discharged out of the cell together with the pure water through the pure water outlet port P2 as described above.

According to the water electrolysis system 1 having the above configuration, the pure water supplied from the pure water inlet port P1 to each water electrolysis cell 10 of the water electrolysis cell stack 13 is electrolyzed in each water electrolysis cell 10 by the electric power from the DC power supply 2, and the oxygen molecules are discharged from the pure water outlet port P2 together with the pure water. At this time, as shown in FIG. Pure water, which is raw material water, flows from there to the upper communication port 43 communicating with the pure water outlet port P2. On the other hand, in the separator 31 on the hydrogen electrode side, as shown in FIG. 4, the generated hydrogen gas flows diagonally through the central region 32 toward the communication port 35 (arrows in the figure).

Here, the main requirements for the reaction channel of the water electrolysis cell 10 are that the reaction channel pressure loss of the oxygen electrode is low from the viewpoint of reducing the power of the pump 53 and the pressure difference between upstream and downstream of the channel, that pure water is sufficiently supplied to the electrode surface, that the cooling function of the cell is ensured, and that the supplied pure water flow rate is sufficiently secured from the viewpoint of preventing water drying up downstream of the channel due to an increase in the void ratio (ratio of air bubbles in the pure water).

Looking at the flow of reaction fluid in the separator 41 on the oxygen electrode side shown in FIG. 3 in light of this point, pure water, which is raw water, flows from the lower communication port 44 to the upper communication port 43 (arrows in the figure), and the oxygen molecules generated in the central region 42 corresponding to the electrode portion 22 flow from the upper communication port 43 to the pure water outlet port P2 together with the electrolyzed water (pure water subjected to water electrolysis) that has not undergone water electrolysis. Therefore, when considering the same reaction area, as shown in the embodiment, the region 42 and the separator 41 are oblong rectangles, and the communication port 44 serving as the pure water supply port is arranged along the long side so that the supply port extends in the longitudinal direction. Moreover, since the channel length is in the direction of the short side, the pressure loss in the reaction channel when flowing through the regions 32 and 42 corresponding to the electrode portion 22 is kept low.

On the other hand, in the water electrolysis cell 10, since the supplied electrolyzed water also plays a role of cooling the cell, increasing the flow rate of supplied pure water is also advantageous for cooling the cell. If the flow rate of the electrolyzed water is too low, the heat generated during the reaction cannot be sufficiently removed, and there is a risk of abnormal overheating and damage to the cell. In addition, when cooling is insufficient, a large temperature change may occur upstream and downstream of the water electrolysis cell 10, but according to the water electrolysis cell 10 of the embodiment, the pure water supply flow rate can be increased and the flow path length is short, so such a situation can be suppressed.

In the water electrolysis cell 10 of the embodiment, only one communication port 25, 35, 45 is provided for discharging hydrogen gas for simplification of the system.

In addition, the vertical position of the communication port for discharging hydrogen gas may be set vertically over the entire surface so as to completely cover from the bottom to the top of the electrode surface (that is, the length may be set so as to substantially correspond to the short sides of the separators 31 and 41). However, in that case, a large amount of hydrogen will remain in the communication port portion during operation, and the amount of hydrogen gas in the water electrolysis cell stack 13 will increase. Therefore, from the viewpoint of safety, it is better to reduce the size of the communication port 35 for discharging hydrogen gas and reduce the amount of hydrogen remaining in the water electrolysis cell stack 13 .

As a method of arrangement, for example, the communication port 35 may be provided only in the lower part of the electrode surface, and the external pipe 71 communicating with the communication port 35 may be provided at a position lower than the lower end of the electrode surface 22 so that coordination water from the oxygen electrode side can be discharged smoothly. Further, in order to ensure the moist state of the electrolyte membrane as much as possible, the communication port 35 may be provided in the upper portion of the electrode surface 22, and the external pipe 71 may be provided at a position higher than the upper end of the electrode surface 22 so that the electrode surface 22 is submerged.

The above is an example of the water electrolysis system 1 using the polymer electrolyte water electrolysis cell 10. However, the polymer electrolyte integrated cell (also referred to as an integrated cell, integrated cell, or reversible cell) in which a polymer electrolyte water electrolysis cell and a fuel cell are integrated has the following problems.

That is, the solid polymer type integrated cell is an energy converter that integrates a solid polymer type water electrolysis cell and a fuel cell and selectively exhibits both functions in one cell. Oxygen is generated at the oxygen generating electrode and hydrogen is generated at the hydrogen generating electrode, which are separated by a solid polymer diaphragm. The generated hydrogen is discharged out of the cell through the reaction channel of the hydrogen generating electrode and, if necessary, is stored in a storage container or supplied directly to hydrogen demand. At this time, not all of the pure water supplied to the reaction channel of the oxygen generating electrode is decomposed into hydrogen and oxygen, and the pure water that is not decomposed is discharged out of the cell through the reaction channel together with the generated oxygen.

On the other hand, in the fuel cell, hydrogen is supplied to the reaction channel of the hydrogen electrode (hydrogen generating electrode of the water electrolysis cell; hereinafter sometimes referred to as "hydrogen electrode"), and gas containing oxygen such as air or oxygen is supplied to the reaction channel of the oxygen electrode (oxygen generating electrode of the water electrolysis cell; hereinafter sometimes referred to as "oxygen electrode") in a humidified state as necessary, and power is generated by connecting a load to the outside.

Along with such power generation, water is produced at the oxygen electrode, and is discharged out of the cell through the reaction channel together with air and oxygen that have not been used in the reaction. Also on the hydrogen electrode side, water generated in the cell is discharged out of the cell through the reaction channel together with hydrogen not used in the reaction.

A normal water electrolysis cell or a fuel cell, like the water electrolysis cell described above, has a stack shape in which a plurality of unit cells are stacked. Therefore, when supplying the reaction fluid from the outside of the cell to each electrode or discharging the reaction fluid from each electrode to the outside of the cell, it is done through a communication port that functions as a manifold that connects the outside of the cell and the reaction flow path. Conventionally, this communication port is common to each electrode of the water electrolysis cell and the fuel cell (for example, Japanese Unexamined Patent Application Publication No. 2006-127807).

Here, the main requirements for the reaction flow path of the water electrolysis cell are, as described above, a low pressure loss in the reaction flow path of the oxygen electrode from the viewpoint of reducing the pump power and the pressure difference between the upstream and downstream sides of the flow path, and a high flow rate of pure water supplied from the viewpoint of supplying sufficient pure water to the electrode surface, ensuring the cooling function of the cell, and preventing depletion of water downstream of the flow path due to an increase in void fraction. On the other hand, the main requirements for the reaction channel of the fuel cell are to increase the flow velocity in the reaction channel of the oxygen electrode from the viewpoint of improving the diffusibility of oxygen to the electrode surface and preventing the reaction channel from being clogged by generated water.

In this case, in order to meet the requirements for the oxygen electrode reaction channel of the water electrolysis cell, it is necessary to increase the channel cross-sectional area. Further, the pure water supplied to the oxygen electrode of the water electrolysis cell and the humidified air (oxygen) supplied to the oxygen electrode of the fuel cell differ in density by about 1,000 times. Therefore, if pure water and humidified air are flowed at the same flow rate, the pressure loss when water is flowed will be overwhelmingly larger. In other words, there are conflicting requirements for both reaction channels, particularly for the oxygen electrode reaction channel, and it is important how to satisfy them.

In this respect, conventionally, the reaction channel was designed according to the more important function of water electrolysis and the fuel cell, or the reaction channel was designed around the midpoint between the needs of both. Therefore, the optimum reaction channel design for both has not been made.

In view of this point, the following describes an embodiment in which the communication port (functioning as a manifold) for the oxygen electrode, which has been used in common by the water electrolysis cell and the fuel cell, is provided exclusively for the communication port (functioning as a manifold) for the oxygen electrode of the water electrolysis cell and the communication port (functioning as a manifold) for the oxygen electrode of the fuel cell, respectively, to solve such problems.

FIG. 5 shows a schematic configuration of a water electrolysis/fuel cell system 101 according to an embodiment. This water electrolysis/fuel cell system 101 has a water electrolysis/fuel cell stack 113 formed by connecting and stacking a plurality of solid polymer integrated cells (unit cells) 110 shown in FIG.

FIG. 6 shows an integrated cell 110 in which a water electrolysis cell and a fuel cell are integrated according to the embodiment. Note that FIG. 6 also shows the flow of the fluid when explaining the flow of the fluid during the water electrolysis operation later.

The integrated cell 110 has an electrode body 121 having a structure in which an electrolyte membrane is sandwiched between current feeders and current collectors from both sides, and a hydrogen electrode side separator 131 and an oxygen electrode side separator 141 which sandwich the electrode body 121 from both sides.

The electrode body 121, the separator 131 on the hydrogen electrode side, and the separator 141 on the oxygen electrode side are provided with a central electrode portion 122, a rear surface of a region 132 corresponding to the electrode portion 122, and various communication ports described below on the outside of the region 142, respectively.

First, hydrogen electrode communication ports 123a, 123b, 133a, 133b, 143a, and 143b are provided on both outer sides of regions 132 and 142 corresponding to the electrode portion 122 and the electrode portion 122 of the rectangular electrode body 121, the hydrogen electrode side separator 131, and the oxygen electrode side separator 141. Similarly, oxygen electrode communication ports 124a, 124b, 134a, 134b, 144a, and 144b for the fuel cell are provided on both outer sides of the electrode portion 122 of the rectangular electrode body 121, the hydrogen electrode-side separator 131, and the oxygen electrode-side separator 141, and regions 132 and 142 corresponding to the electrode portions.

On the other hand, cooling water communication openings 125a, oxygen electrode communication openings 126a, cooling water communication openings 135a, oxygen electrode communication openings 136a, cooling water communication openings 145a, and oxygen electrode communication openings 146a are alternately provided below the outer and lower regions 132 and 142 corresponding to the electrode portions 122 and the electrode portions 122 of the rectangular electrode body 121, the hydrogen electrode side separator 131, and the oxygen electrode side separator 141, respectively. is provided. In the electrode assembly 121, the hydrogen electrode side separator 131, and the oxygen electrode side separator 141, oxygen electrode communication openings 126b, cooling water communication openings 125b, oxygen electrode communication openings 136b, cooling water communication openings 135b, oxygen electrode communication openings 146b, and cooling water communication openings 145b are provided alternately above the outer regions 132 and 142 corresponding to the electrode portions 122 and the electrode portions 122, respectively. are

Sealing materials are arranged around the communication openings of the separator 131 on the hydrogen electrode side and the separator 141 on the oxygen electrode side, as described below. First, as for the separator 131 on the hydrogen electrode side, a sealing material 137 (indicated by a dashed line) surrounding each of the oxygen electrode communication ports 134a and 134b is arranged independently on the outer periphery of the oxygen electrode communication ports 134a and 134b. A sealing material 138 (indicated by broken lines) is arranged around the hydrogen electrode communication ports 133a and 133b and the central region 132 to integrally surround them. Sealing materials 139 (indicated by dashed lines) are arranged around the cooling water communication ports 135a and 135b and the oxygen electrode communication ports 136a and 136b, respectively, to independently surround them.

On the other hand, regarding the separator 141 on the oxygen electrode side, sealing materials 147 are arranged independently around the oxygen electrode communication ports 143a and 143b for the fuel cell. Sealing materials 148 are arranged around the cooling water communication ports 145a and 145b so as to surround the respective communication ports independently. A sealing material 149 is arranged to integrally surround the remaining oxygen electrode communication ports 146a and 146b and the central region 142. As shown in FIG.

These sealing materials 137 to 139 and 147 to 149 prevent each fluid from flowing outside of a predetermined path. Further, in the present embodiment, at least the central regions 132 and 142, which serve as reaction channels, of the separator 131 on the hydrogen electrode side and the separator 141 on the oxygen electrode side are made of materials such as embossing, mesh, punching metal, etc., unlike the materials that constitute general straight channels and serpentine channels. As a result, flow paths are formed in the separator 131 on the hydrogen electrode side and the separator 141 on the oxygen electrode side so that the fluid can flow in both the vertical direction and the horizontal direction.

Next, referring back to FIG. 5, the water electrolysis/fuel cell system 101 employing the water electrolysis/fuel cell stack 113 in which the integrated cells 110 are stacked will be described. In FIG. 5, the configuration of the members, devices, etc. specified by the same reference numerals as those used in the explanation of FIG. 1 indicates the configuration of the same members, devices, etc. as the water electrolysis system 1 of FIG.

As described above, the integrated cell 110 employed in this water electrolysis/fuel cell system 101 has many types of communication ports that function as manifolds, so the number of ports provided in the water electrolysis/fuel cell stack 113 communicating with each communication port is also large. Specifically, the pure water inlet port P1 communicates with the oxygen electrode communication ports 126a, 136a and 146a, the pure water outlet port P2 communicates with the oxygen electrode communication ports 126b, 136b and 146b, and the hydrogen outlet port P3 communicates with the hydrogen electrode communication ports 123b, 133b and 143b. Since the water electrolysis/fuel cell system 101 is capable of fuel cell operation, a hydrogen inlet port P4 is newly provided as an introduction port for hydrogen gas, which is a raw material gas.

The hydrogen inlet port P4 communicates with the hydrogen electrode communication ports 123a, 133a and 143a. Further, an air inlet port P5 communicating with oxygen electrode communication ports 124a, 134a, 144a for fuel cells is provided, and an air outlet port P6 communicating with oxygen electrode communication ports 124b, 134b, 144b for fuel cells is provided. Furthermore, a cooling water outlet port P7 communicating with the cooling water communication ports 125a, 135a and 145a and a cooling water inlet port P8 communicating with the cooling water communication ports 125b, 135b and 145b are newly provided.

A flow path 151 is connected to the hydrogen inlet port P4, and hydrogen gas from a hydrogen gas supply source (not shown) can be introduced into the hydrogen inlet port P4. The flow path 151 is provided with a regulating valve V7, an electromagnetic valve V8, and a pressure gauge 152. As shown in FIG. A flow path 153 communicating with the gas layer of the tank 72 is connected to the downstream side of the solenoid valve V8 in the flow path 151 . A hydrogen pump 154 is provided in the flow path 153 .

A flow path 163 through which air supplied by a blower 161 is introduced via a humidity exchanger 162 is connected to the air inlet port P5. A check valve 164 is provided in the flow path 163 . A flow path 165 is connected to the air outlet port P6 so that air coming out of the water electrolysis/fuel cell stack 113 is discharged to the outside through the humidity exchanger 162 . The flow path 165 is provided with an electromagnetic valve V9.

A pipe 181 is connected to the cooling water outlet port P7, and the cooling water whose temperature has been raised is sent by a hydrogen pump 182 to a heat exchanger 183, where it is heat-exchanged with cooling water from the outside to lower its temperature. As for the water source of the cooling water, for example, city water such as tap water, ground water, or the like can be used. Also, the cooling water whose temperature has been raised after heat exchange may be appropriately supplied to a heat demand destination.

In addition to the direct-current power supply 2 , a power load 3 is connected to the water electrolysis/fuel cell stack 113 .

The water electrolysis/fuel cell system 101 is configured as described above, and the operation method thereof will now be described.

[Water electrolysis operation]
First, the solenoid valve V2 is opened, and the other solenoid valves V3, V6, V8 and V9 are closed. The pure water stored in the tank 51 is supplied to the pure water inlet port P1 of the water electrolysis/fuel cell stack 113 through the pipe 52 by activating the pump 53 . The pure water inlet port P1 communicates with the oxygen electrode communication ports 126a, 136a and 146a, and as shown in FIG. The water is discharged outside and returned to the tank 51 through the pipe 61 .

When DC power is supplied from the DC power source 2 to the water electrolysis/fuel cell stack 113 in this state, protons (H ⁺ ) and oxygen are generated on the oxygen electrode. The generated protons (H ⁺ ) move through the electrode assembly 121 from the oxygen electrode to the hydrogen electrode accompanied by coordinated water, and as shown in FIG. In the tank 72, the hydrogen gas separated into gas and liquid is sent through the pipe 71 to the back pressure valve V5, where the pressure is adjusted and then sent to a hydrogen demand destination or a hydrogen storage tank (not shown) outside the system.

The pure water separated in the tank 72 is sent to the tank 51 through the pipe 73 using the pressure difference between the hydrogen side and the oxygen side. An existing known technique may be used to feed the pure water in the tank 72 to the tank 51 .

On the other hand, the oxygen generated in the water electrolysis/fuel cell stack 113 is returned to the tank 51 together with the pure water that has not been decomposed through the communication ports 126b, 136b, and 146b through the pure water outlet port P2 and the piping 61. The oxygen gas separated into gas and liquid in the tank 51 is discharged outside the system through the pipe 63 . If oxygen gas is required, an oxygen storage tank (not shown) may be provided separately and sent to the oxygen storage tank. The pure water separated in the tank 51 is again supplied to the water electrolysis/fuel cell stack 113 as pure water for electrolysis.

As described above, the pipes 181 and 184 are cooling water systems and serve to remove heat generated by electrolysis. The removed heat may be supplied to the thermal demand via heat exchanger 183, as previously described. However, in the case of water electrolysis operation, cooling is possible with electrolyzed water (pure water) for electrolysis, so cooling water does not need to be circulated.

[Fuel cell operation]
Next, the case of fuel cell operation will be described. During fuel cell operation, the solenoid valves V8 and V9 are opened and the other solenoid valves V2, V3 and V6 are closed. On the hydrogen side, hydrogen pressure-regulated by the regulating valve V7 is supplied through the flow path 151 to the hydrogen inlet port P4. As shown in FIG. 7, the hydrogen supplied to the hydrogen inlet port P4 passes through the communication port 123a, the central electrode portion 122, and the hydrogen electrode communication port 123b and is discharged out of the cell from the hydrogen outlet port P3. By activating the hydrogen pump 154 here, the discharged hydrogen gas is sucked into the hydrogen pump 154 and supplied again to the water electrolysis/fuel cell stack 113 .

On the other hand, on the oxygen side, air is sucked from the atmosphere by activating the blower 161, and after being appropriately humidified by the humidity exchanger 162, the air passes through the pipe 163 and is supplied from the air inlet port P5 into the water electrolysis/fuel cell stack 113. Since the air inlet port P5 communicates with the oxygen electrode communication port 144a, the air is discharged from the oxygen electrode communication port 144a, through the central region 142, from the communication port 144b, and from the water electrolysis/fuel cell stack 113 from the air outlet port P6. Then, it is exhausted to the atmosphere through the pipe 165 and the humidity exchanger 162 . When the connection with the external power load 3 is turned on in this state, hydrogen is decomposed into protons on the hydrogen electrode, and protons and oxygen combine on the oxygen electrode to generate water and electricity. The generated electricity will be supplied to the power load 3 .

The hydrogen gas not used in the fuel cell operation reaction is discharged from the hydrogen outlet port P3 to the outside of the water electrolysis/fuel cell stack 113 through the hydrogen electrode communication port 123b, and supplied to the tank 72 through the pipe 71. The hydrogen gas separated into gas and liquid in the tank 72 is supplied again to the water electrolysis/fuel cell stack 113 by the hydrogen pump 154 . The amount of hydrogen consumed in the reaction is appropriately supplied from the outside at a constant pressure by the function of the regulating valve V7.

On the other hand, the air not used in the reaction and the water produced by the reaction pass through the communication port 144b and are discharged outside the water electrolysis/fuel cell stack 113 from the air outlet port P6. Then, it is sent to the humidity exchanger 162 via the pipe 165 . In the humidity exchanger 162, after humidifying the air sent from the blower 161, the humidified air is exhausted from the system through the pipe 165. Therefore, even if the air sent from the blower 161 is of low humidity, it is sufficiently humidified by the humidity exchanger 162 before being supplied to the water electrolysis/fuel cell stack 113 . It should be noted that circulation of cooling water in a cooling water system constituted by pipes 181 and 184 is essential for fuel cell operation.

When switching from the water electrolysis operation to the fuel cell operation, the power supply from the DC power supply 2 is first stopped. Next, on the hydrogen side, the solenoid valve V6 is opened to release the pressure of the entire hydrogen system to the outside and reduce the pressure in the system to near normal pressure. On the oxygen side, the pump 53 is stopped, the solenoid valve V2 is closed, the solenoid valve V9 is opened, and then the blower 161 is started, and the pure water remaining in the electrode portion 122 of the electrode body 121 and its surroundings is discharged from the communication port 144b to the outside of the water electrolysis/fuel cell stack 113 via the air outlet port P6. As for the subsequent method for drying the stack 113 of the water electrolysis/fuel cell stack 113, a conventional technique may be appropriately applied.

Also, when switching the operation from the fuel cell operation to the water electrolysis operation, the connection with the power load 3 is first cut off. Next, for the hydrogen side, after stopping the hydrogen pump 154, the electromagnetic valve V8 is closed. As for the oxygen side, after the blower 161 is stopped, the electromagnetic valve V9 is closed. After that, the water electrolysis operation should be started as usual.

Regarding the water electrolysis operation and the fuel cell operation as described above, in the case of the conventional integrated cell, as described above, the communication port of the oxygen electrode was used in common during the water electrolysis operation and the fuel cell operation. Therefore, as described above, it was impossible to satisfy the requirements for both reaction channels.

On the other hand, in the example using the integrated cell 110 according to the embodiment, it is possible to largely change the channel cross-sectional area and the channel length between the water electrolysis operation and the fuel cell operation.

That is, during the water electrolysis operation, as shown in FIG. 6, when looking at the flow of the reactant fluid in the separator 141 on the oxygen electrode side, pure water, which is raw material water, flows from the lower oxygen electrode communication port 146a to the upper oxygen electrode communication port 146b (arrow in the figure), and the oxygen molecules generated in the central region 142 corresponding to the electrode portion 122 are connected to the upper oxygen electrode together with the electrolyzed water that has not undergone water electrolysis (the pure water subjected to water electrolysis). It flows from the port 146b to the pure water outlet port P2. Therefore, when considering the same reaction area, as shown in the embodiment, the region 142 and the separator 141 are oblong rectangles, and the oxygen electrode communication port 146a serving as the pure water supply port is arranged along the long side and extends in the longitudinal direction. Moreover, since the channel length is in the lateral direction, the pressure loss in the reaction channel is kept low.

On the other hand, when the fuel cell is operated, the flow channel cross-sectional area needs to be small in order to ensure the requirements for the oxygen electrode reaction flow channel. However, as shown in FIG. 7, the air flows from the oxygen electrode communication port 144a located on the short side of the rectangle to the oxygen electrode communication port 144b located on the opposite short side through the region 142. Therefore, the flow channel cross-sectional area is smaller than when flowing from the long side to the long side during the water electrolysis operation. Similarly, the hydrogen gas also flows from the communication port 123a located on the short side toward the hydrogen electrode communication port 123b located on the opposite short side, so that the cross-sectional area of the flow path at that time is smaller than that during the water electrolysis operation.

As described above, in the integrated cell 110 according to the embodiment of the present invention, the communication port of the oxygen electrode, which was conventionally used in common for the water electrolysis cell and the fuel cell, is divided into the communication port for the oxygen electrode of the water electrolysis cell and the communication port for the oxygen electrode of the fuel cell, and is provided exclusively for each. Furthermore, since the electrode body 121 and the separators 131 and 141 are rectangular and horizontally long and arranged vertically, pure water, which is raw material water, can flow in the lateral direction in water electrolysis operation, while humidified air can flow in the longitudinal direction in fuel cell operation.

As a result, even though the same cell is used, the cross-sectional area of the reaction channel can be significantly changed between water electrolysis operation and fuel cell operation, and the channel length, which has a large impact on pressure loss, can also be changed significantly. As a result, the requirements required for the reaction flow path of the water electrolysis cell and the requirements required for the fuel cell can be satisfied under more ideal conditions even with the same cell.

In order to quantitatively demonstrate this, the extent to which pressure loss and flow velocity in the flow path can be changed between the conventional separator and the separator according to the embodiment with the same electrode shape will be shown below.

First, flow path pressure loss: ΔP is expressed by the following formula.
ΔP=λ・(L/D)・(ρ・v2/2) Equation (1)
In equation (1), λ is the pipe friction coefficient, L is the channel length, D is the channel cross-sectional area, ρ is the fluid density, and v is the flow velocity.

FIG. 8 shows an outline of how the flow path pressure loss changes when the aspect ratio of the electrodes is changed under the condition that the electrode area is fixed. The graph of FIG. 8 is the result of evaluation assuming that the value of the pipe friction coefficient is constant. When the aspect ratio (transverse direction X: longitudinal direction Y) of the electrodes is 1:2, the flow path pressure loss can be reduced to 1/16 times when the fluid is passed in the lateral direction as compared to when the fluid is passed in the longitudinal direction. Furthermore, when the aspect ratio of the electrodes is 1:4, it can be reduced to 1/256 times. The pipe frictional resistance varies depending on the Reynolds number and whether the flow is laminar or turbulent, but the maximum difference is estimated to be about 5 times when the aspect ratio is about 1:4. By simple calculation, when the aspect ratio is 1:2, it can be reduced to 1/3 or less, and when it is 1:4, it can be reduced to 1/51 or less. Here, the density of gas and water differ by about 1000 times, but the flow rate of humidified air when actually operating a fuel cell with a conventional integrated cell is about 10 times the flow rate of pure water when water electrolysis is performed.

Considering these points, the difference in flow path pressure loss when humidified air is actually passed through the integrated cell and when pure water is passed is 3.3 times or less when the aspect ratio is 1:2, and 1/5 times or less when the aspect ratio is 1:4, when pure water is passed in the lateral direction with respect to the case where humidified air is passed in the longitudinal direction.

When a common communication port is used as in the conventional case, the difference in flow path pressure loss when pure water is flowed is 10 times that when humidified air is flowed regardless of the aspect ratio of the flow path (water density: 1,000 times vs. humidified air density, water flow rate: 1/10 times vs. humidified air flow rate). From this, it can be seen that the embodiment of the present invention can dramatically reduce the flow path pressure loss during water electrolysis. However, during water electrolysis operation, oxygen is generated at the oxygen electrode due to electrolysis, so the flow form of the oxygen electrode reaction flow path changes from a single-phase flow of pure water to a gas-liquid two-phase flow in which oxygen gas increases toward the cell outlet. Since the channel pressure loss of gas-liquid two-phase flow is higher than that of single-phase flow, it is necessary to determine the aspect ratio of the channel in consideration of this point.

Next, how the flow velocity v in the flow channel changes when the aspect ratio of the electrodes is changed. If the flow rate is fixed at Q, the only difference is due to the difference in the cross-sectional area A, so it can be obtained by a simple calculation of v = Q / A. The difference between flowing the flow rate Q in the lateral direction and the longitudinal direction is two times when the aspect ratio is 1:2, and four times when the aspect ratio is 1:4. From the analogy of mass transfer and heat transfer, the mass transfer coefficient increases in proportion to the 0.5th power of the flow velocity if the flow is laminar and to the 0.8th power of the flow velocity if the flow is turbulent. Therefore, if the flow velocity is four times higher, the material transfer rate is doubled when the flow is laminar, and tripled when turbulent, so that not only can diffusion of oxygen from the reaction channel to the electrode surface be promoted, but also the effect of discharging water produced by the reaction is increased.

If the diffusion of oxygen to the electrode surface is promoted, it becomes possible to operate the fuel cell at a higher current density (=current value/electrode area) than before, and the power density per unit cell can be improved. Regarding this point as well, when the communication port is shared as in the conventional case and the cell is designed so as to reduce the flow path pressure loss during water electrolysis, when the aspect ratio is 1:4, the flow velocity is 1/4 times. As a result, it can only be operated at lower current densities.

From the above, it can be seen that the channel pressure loss during water electrolysis and the flow velocity during fuel cell can be both reduced by the shape of the channel and the separator adopted in the integrated cell 110 of the embodiment of the present invention.

6 and 7, the pure water communication ports 126a, 126b, 136a, 136b, 146a, 146b and the cooling water communication ports 125a, 125b, 135a, 135b, 145a, 145b are divided into a plurality. This allows the fluid to be evenly distributed in the reaction channels. In addition to simply dividing the fluid into a plurality of parts, the vertically opposed communication ports are provided so that their uses are alternated, so that the fluid can be uniformly distributed in this respect as well.

By the way, in the above embodiment, the water electrolysis cell 10 and the integrated cell 110 are both arranged horizontally and vertically, and are stacked horizontally to form the water electrolysis cell stack 13 and the water electrolysis/fuel cell stack 113, respectively. That is, when rectangular cells are arranged vertically so that raw material water or the like is allowed to flow from the side, the pressure difference due to the head pressure between the upper and lower parts of the cells increases during water electrolysis operation (the lower part of the cells receives a strong pressure). Therefore, it is necessary to design the entire cell so that it can withstand the strong pressure applied to the lower portion of the cell. Therefore, it is preferable to install the cell horizontally so that the pressure difference received within the cell can be reduced.

In addition, when the fuel cell is operated, water generated on both the oxygen side and the hydrogen side is drained from the electrode surface through the manifold (by free fall due to gravity) to the outside of the cell. From this point of view as well, it is preferable that each of the above-described rectangular cells is horizontally long.

By the way, since the integrated cell 110 described above is used in an upright state (a state in which it is arranged horizontally and stands vertically), there is a possibility that reaction-generated water will accumulate in the lower edge portion of the sealing member 149 shown in FIG. If the reaction product water accumulates in this manner and the electrode surface (the portion corresponding to the central region 142) is submerged, the electrode area that can contribute to the reaction is reduced, resulting in a drop in power generation efficiency.

In order to deal with such a situation, the oxygen electrode communication port 144b through which air and water produced by the reaction are discharged is positioned below the bottom of the electrode surface (indicated by the broken line b in the figure) and the uppermost portion of the lower side of the sealing material 149 (indicated by the broken line c in the figure). It can be proposed to set the arrangement so that it is located below the uppermost portion of the sealing material 149 on the lower side.

As a result, the reaction product water does not reach the electrode surface and is discharged from the oxygen electrode communication port 144b without submerging the electrode surface. Therefore, it is possible to prevent the electrode from being submerged due to the accumulation of reaction product water, and prevent the electrode area from being reduced and the power generation efficiency from being lowered.

INDUSTRIAL APPLICABILITY The present invention is useful for water electrolysis using a solid polymer water electrolysis cell in which power feeders are arranged on both sides of an electrolyte membrane and separators are arranged on the outside of each, and water electrolysis and fuel cells using a solid polymer type water electrolysis fuel cell integrated cell in which feeders and current collectors are arranged on both sides of the electrolyte membrane and separators are arranged on the outside of each.

1 Water Electrolysis System 2 DC Power Supply 3 External Load 10 Water Electrolysis Cell 11, 12 End Plate 13 Water Electrolysis Cell Stack 21 Electrode Body 22 Electrode Part 23, 24, 25, 33, 34, 35, 43, 44, 45 Communication Port 31 Hydrogen Electrode Side Separator 32, 42 Area 36, 37, 38, 46, 47 Seal Material 41 Oxygen Electrode Side Separator 51, 72 Tank 52, 59, 74 Piping 53 Pump P1 Pure water inlet port P2 Pure water outlet port P3 Hydrogen outlet port P4 Hydrogen inlet port P5 Air inlet port P6 Air outlet port P7 Cooling water outlet port P8 Cooling water inlet port 101 Water electrolysis/fuel cell system 101
110 integrated cell 111, 112 end plate 113 water electrolysis/fuel cell stack 121 electrode body 122 electrode part 123a, 123b, 133a, 133b, 143a, 143b hydrogen electrode communication port 124a, 124b, 134a, 134b, 144a, 144b oxygen electrode communication port 131 Hydrogen electrode side separators 132, 142 Regions 137, 138, 139, 147, 148, 149 Sealing material 141 Oxygen electrode side separators 151, 153, 163, 165 Flow path 154 Hydrogen pump

Claims (8)

A water electrolysis device in which a plurality of solid polymer water electrolysis cells are stacked, wherein power feeders are arranged on both sides of an electrolyte membrane, and separators are placed outside each power feeder.
The solid polymer type water electrolysis cells are rectangular, and the water electrolysis cells are horizontally long and vertically arranged and horizontally stacked,
At the end of one short side of each rectangular water electrolysis cell, a communication port for discharging hydrogen gas is arranged outside the electrode portion of the water electrolysis cell in the longitudinal direction of the water electrolysis cell ,
The communication port for discharging hydrogen gas is formed at a position lower than the lower end of the electrode portion,
The water electrolysis device, wherein the shape of the electrode portion is oblong such that the flow path pressure loss when the fluid is passed in the lateral direction of the water electrolysis cell is 1/16 or less of the flow path pressure loss when the fluid is passed in the longitudinal direction of the water electrolysis cell. 2. The water electrolysis device according to claim 1, wherein the electrolyzed water flows in the lateral direction of the water electrolysis cell. 2. The water electrolysis apparatus according to claim 1, wherein a communication port for supplying water is arranged on the lower long side of each rectangular water electrolysis cell, and a communication port for discharging electrolyzed water and oxygen gas is arranged on the upper long side of each water electrolysis cell. A method for electrolyzing water using the water electrolysis device according to any one of claims 1 to 3,
A water electrolysis method, characterized in that raw material water is supplied into the water electrolysis cell from the lower long side of the rectangular water electrolysis cell toward the upper long side of the water electrolysis cell. A water electrolysis system using the water electrolysis device according to any one of claims 1 to 3,
a power supply device that supplies DC power to the water electrolysis device;
a raw water supply channel for supplying raw water to the water electrolysis device;
a hydrogen gas release path for releasing hydrogen gas generated in the water electrolysis device to the outside of the system;
an oxygen gas release path for releasing oxygen gas generated in the water electrolysis device to the outside of the system;
A water electrolysis system, comprising: A water electrolysis/fuel cell device in which a plurality of solid polymer type water electrolysis fuel cell integrated cells are stacked, wherein feed/collectors are arranged on both sides of an electrolyte membrane, and separators are further arranged outside each feed/collector,
The solid polymer type water electrolysis fuel cell integrated cell is rectangular, and the water electrolysis fuel cell integrated cell is horizontally long and vertically arranged and stacked horizontally,
A communication port for supplying raw material water during water electrolysis operation and a communication port for supplying cooling water are arranged on the lower long side of each rectangular water electrolysis fuel cell integrated cell,
A communication port for discharging electrolyzed water and oxygen gas during water electrolysis operation is arranged on the upper long side of each water electrolysis fuel cell integrated cell,
A communication port for discharging hydrogen gas during water electrolysis operation, a communication port for hydrogen gas supply during fuel cell operation, and a communication port for supplying air or oxygen gas are formed on the short side of each water electrolysis fuel cell integrated cell,
The water electrolysis/fuel cell device is characterized in that the shape of the electrode portion of the water electrolysis fuel cell integrated cell is oblong with an aspect ratio of 1:2 or more, or is oblong such that the pressure loss of the flow path when the fluid is flowed in the longitudinal direction of the water electrolysis fuel cell integrated cell is 1/16 or less of the flow path pressure loss when the fluid is flowed in the longitudinal direction of the water electrolysis fuel cell integrated cell. A method for switching between water electrolysis operation and fuel cell operation using the water electrolysis/fuel cell device according to claim 6,
During the water electrolysis operation, raw water is supplied into the water electrolysis fuel cell integrated cell from the lower long side of the rectangular water electrolysis fuel cell integrated cell toward the upper long side of the water electrolysis fuel cell integrated cell,
A water electrolysis/fuel cell operation method, characterized in that, when the fuel cell is operated, a raw material gas is supplied into the water electrolysis fuel cell integrated cell from the short side of the rectangular water electrolysis fuel cell integrated cell toward the opposite short side. A water electrolysis/fuel cell system using the water electrolysis/fuel cell device according to claim 6,
a power supply device that supplies DC power to the water electrolysis/fuel cell device;
a raw water supply path for supplying raw water to the water electrolysis/fuel cell device;
a hydrogen gas release path for releasing hydrogen gas generated in the water electrolysis/fuel cell device to the outside of the system;
an oxygen gas release path for releasing oxygen gas generated in the water electrolysis/fuel cell device to the outside of the system;
a hydrogen gas supply path for supplying hydrogen gas to the water electrolysis/fuel cell device;
a gas supply path for supplying oxygen gas or air to the water electrolysis/fuel cell device;
and an oxygen gas discharge path for discharging water generated in the water electrolysis/fuel cell device to the outside of the system.

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