Separation system and separation method

Abstract

To raise a separation factor α and improve hydrogen isotope separation performance.SOLUTION: A separation system includes: a fuel battery cell having an anode passage and a cathode passage including a polymer electrolyte and a catalyst, and sandwiching a polymer electrolyte; raw material fluid supply means connected to an anode supply passage and supplying a raw material fluid containing a hydrogen isotope; cathode gas supply means connected to a cathode supply passage and supplying a fluid containing inactive gas; hydrogen concentration acquisition means for acquiring a hydrogen concentration of a fluid flowing in the anode supply passage and an anode discharge passage; a control unit for calculating as α=Tb Ha / Ta Hb, a separation factor α from a concentration ratio of a hydrogen isotope Tb to light hydrogen Hb of the anode supply passage, and a concentration ratio of a hydrogen isotope Ta to light hydrogen Ha of the anode discharge passage; and adjustment means for adjusting the separation factor α by being controlled by the control unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a separation system and a separation method. [Background technology]

[0002] A known technique for separating hydrogen isotopes is to separate water containing large amounts of deuterium and tritium (tritium) using an electrolysis cell having an ion exchange membrane and a catalyst (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-011903 Summary of the Invention [Problem to be solved by the invention]

[0004] In systems that separate hydrogen isotopes, the separation factor α of the electrolytic cell indicates the degree of separation of hydrogen isotopes. The separation factor α is calculated by dividing the ratio of the hydrogen isotope concentration to the proton concentration at the anode inlet of the electrolytic cell by the ratio of the hydrogen isotope concentration anode to the proton concentration at the anode outlet of the electrolytic cell. The separation factor α decreases due to deterioration of the decomposition performance of the electrolytic cell over time. There is a need to improve this decreased separation factor α. However, the above-mentioned prior art does not describe any such efforts, and there is room for improvement in the prior art.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a separation system and a separation method that can increase the separation factor α and improve hydrogen isotope separation performance even when the separation factor α decreases due to performance degradation or the like. [Means for solving the problem]

[0006] [1] A separation system (1) according to one aspect of the present invention comprises: a fuel cell (11) comprising an electrolyte membrane and a catalyst, and having an anode flow path (11A) on the anode side sandwiching the electrolyte membrane and a cathode flow path (11C) on the cathode side sandwiching the electrolyte membrane; an anode discharge flow path (123) and an anode supply flow path (122) communicating with the anode flow path (11A); a cathode discharge flow path (223) and a cathode supply flow path (222) communicating with the cathode flow path (11C); a raw material fluid supply means (60) connected to the anode supply flow path (122) for supplying a raw material fluid containing hydrogen isotopes; a cathode gas supply means (260) connected to the cathode supply flow path (222) for supplying a fluid containing an inert gas; hydrogen concentration acquisition means (321, 322) for acquiring hydrogen concentrations of fluids flowing through the anode supply flow path (122) and the anode discharge flow path (123); A separation factor α is calculated from the concentration ratio of hydrogen isotope Tb to hydrogen Hb in the anode supply flow path (122) and the concentration ratio of hydrogen isotope Ta to hydrogen Ha in the anode discharge flow path (123), which are output from the hydrogen concentration acquisition means (321, 322). α=Tb·Ha / Ta·Hb a control unit (140) that calculates the an adjusting means (300) that adjusts the separation factor α under the control of the control unit (140); having This solved the above problem.

[0007] According to the above configuration, a raw material fluid containing hydrogen isotopes is supplied from the raw material fluid supply means to the anode flow channel, and a fluid containing an inert gas is supplied from the cathode gas supply means to the cathode flow channel to separate hydrogen isotopes. When the hydrogen isotope separation performance is reduced due to factors such as an extended operating time of the fuel cell, the adjustment means can adjust the separation factor α to improve it. In other words, even if the separation factor α is reduced due to performance degradation or the like, the adjustment means can increase the separation factor, thereby improving the separation factor. This allows the hydrogen isotope separation performance to be restored. Here, Ta / Ha is the concentration ratio of the hydrogen isotope Ta to the proton Ha in the anode discharge flow path, and Tb / Hb is the concentration ratio of the hydrogen isotope Tb to the proton Hb in the anode supply flow path.

[0008] [2] The separation system (1) of the present invention is the above-mentioned [1], The adjusting means (300) includes an adjusting valve (333) provided in the anode discharge flow path (123), the control unit (140) reduces the flow rate of the fluid flowing through the anode discharge channel (123) by the adjustment valve (333) when the separation coefficient α is smaller than a predetermined value; It is possible.

[0009] According to the above configuration, when the hydrogen isotope separation performance decreases due to factors such as catalyst degradation as the fuel cell operates for a long time, the control unit controls the adjustment valve to reduce the flow rate of the fluid flowing through the anode discharge flow path. As a result, even if the separation factor α decreases due to factors such as the fuel cell operating for a long time, the adjustment unit can increase the separation factor, thereby improving the separation factor. This makes it possible to restore the hydrogen isotope separation performance.

[0010] [3] The separation system (1) of the present invention is the above-mentioned [1], The adjusting means (300) includes a temperature control device (301) that controls the temperature (heat medium temperature) of the fuel cell (11), the control unit (140) increases the temperature of the fuel cell (11) by the temperature control device (301) when the separation coefficient α is smaller than a predetermined value; It is possible.

[0011] According to the above configuration, the fuel cell is provided with a heat exchanger or the like as a temperature control device that adjusts the temperature of the fuel cell. When the hydrogen isotope separation performance decreases due to factors such as an increase in the operating time of the fuel cell, the control unit controls the temperature control device to increase the heat medium temperature of the heat exchanger in the temperature control device, thereby increasing the temperature in the fuel cell. As a result, even if the separation factor α decreases due to factors such as an increase in the operating time of the fuel cell, the temperature control device can increase the amount of water vapor in the fuel cell, thereby increasing the separation factor and improving the separation factor. This makes it possible to restore the hydrogen isotope separation performance. In this case, when increasing the amount of water vapor in the fuel cell, it is necessary to increase the stack temperature and, at the same time, to increase the dew point of the gas supplied to the fuel cell.

[0012] [4] The separation system (1) of the present invention is the above-mentioned [3], the temperature control device (301) is capable of controlling the relative humidity of the fluid flowing through the anode supply channel (122); the control unit (140) controls the temperature control device (301) to increase the relative humidity of the fluid flowing through the anode supply channel (122) when the separation coefficient α is smaller than a predetermined value; It is possible.

[0013] According to the above configuration, when the hydrogen isotope separation performance deteriorates due to factors such as an increase in the operating time of the fuel cell, the control unit controls the temperature control device to increase the relative humidity of the fluid flowing through the anode supply flow path. As a result, even if the separation factor α decreases due to factors such as an increase in the operating time of the fuel cell, the temperature control device can increase the amount of water vapor in the fuel cell, thereby increasing the separation factor and improving the separation factor. This allows the hydrogen isotope separation performance to be restored. In this case, when increasing the amount of water vapor in the fuel cell, it is necessary to increase the stack temperature and, at the same time, to increase the dew point of the gas supplied to the fuel cell.

[0014] [5] The separation system (1) of the present invention is the above-mentioned [3], the temperature control device (301) is capable of controlling the relative humidity of the fluid flowing through the cathode supply flow path (222); the control unit (140) controls the temperature control device (301) to increase the relative humidity of the fluid flowing through the cathode supply flow path (222) when the separation coefficient α is smaller than a predetermined value; It is possible.

[0015] According to the above configuration, when the hydrogen isotope separation performance deteriorates due to factors such as an increase in the operating time of the fuel cell, the control unit controls the temperature control device to increase the relative humidity of the fluid flowing through the cathode supply flow path. As a result, even if the separation factor α decreases due to factors such as an increase in the operating time of the fuel cell, the temperature control device can increase the amount of water vapor in the fuel cell, thereby increasing the separation factor and improving the separation factor. This allows the hydrogen isotope separation performance to be restored. In this case, when increasing the amount of water vapor in the fuel cell, it is necessary to increase the stack temperature and, at the same time, to increase the dew point of the gas supplied to the fuel cell.

[0016] [6] The separation system (1) of the present invention is the above-mentioned [1], The adjusting means (300) includes a cathode supply flow rate control means (262) for adjusting the flow rate of the fluid [inert gas] flowing through the cathode supply flow path (222), When the separation coefficient α is smaller than a predetermined value, the control unit (140) increases the flow rate of the fluid flowing through the cathode supply flow path (222) by the cathode supply flow rate control means (262). It is possible.

[0017] According to the above configuration, when the hydrogen isotope separation performance is reduced due to factors such as an increase in the operating time of the fuel cell, the control unit controls the cathode supply flow rate control means to increase the flow rate of the fluid flowing through the cathode supply flow path. This makes it possible to increase the separation factor α and improve the separation factor, even if the separation factor α has decreased due to factors such as an increase in the operating time of the fuel cell. This makes it possible to restore the hydrogen isotope separation performance.

[0018] [7] Another aspect of the present invention provides a separation method in the separation system (1) according to any one of [1] to [6] above, When the separation factor α is smaller than a predetermined value, the separation factor α is increased by controlling one or more selected from the flow rate of the fluid flowing through the anode discharge flow path (123), the temperature of the fuel cell (11), the relative humidity of the fluid flowing through the anode supply flow path (122), the flow rate of the fluid flowing through the cathode supply flow path (222), and the relative humidity of the fluid flowing through the cathode supply flow path (222). It is possible.

[0019] According to the above configuration, when the hydrogen isotope separation performance is reduced due to factors such as an increase in the operating time of the fuel cell, by adopting one or more methods selected from the group consisting of reducing the flow rate in the anode flow channel, increasing the amount of water vapor in the fuel cell, and increasing the flow rate in the cathode supply flow channel, the separation factor α can be increased and improved even if it has decreased, thereby recovering the hydrogen isotope separation performance. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a separation system and a separation method that can increase the separation factor α even when the separation factor α decreases due to performance degradation or the like, thereby improving hydrogen isotope separation performance. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram illustrating an embodiment of a separation system according to the present invention. [Figure 2] 1 is a graph showing an embodiment of a separation method according to the present invention. [Figure 3] 1 is a graph showing an embodiment of a separation method according to the present invention. [Figure 4] 1 is a graph showing an embodiment of a separation method according to the present invention. [Figure 5] 1 is a graph showing an embodiment of a separation method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a separation system according to the present invention will be described with reference to the drawings. In the present invention, among the three isotopes of hydrogen, deuterium ( 2 H or D) and tritium with mass number 3 ( 3 H or T) are collectively called "hydrogen isotopes," and hydrogen with mass number 1 ( 1 H or H) is called "light hydrogen". Furthermore, gases and liquids are collectively referred to as "fluids." In the present invention, fluids also include those containing liquid in gases and those containing gas in liquids. Fluids are preferably gases or those containing liquid in gases. Furthermore, gases may also be referred to as gases. In addition, in each drawing used in the following description, characteristic portions may be enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may differ from the actual ones. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited to them and can be implemented with appropriate changes within the scope of the present invention.

[0023] "Separation System" 1 is a schematic diagram showing a separation system according to this embodiment, in which reference numeral 1 denotes the separation system. 1, a separation system 1 according to this embodiment includes a first separation device (fuel cell) 10, an anode-side flow path 200A that communicates with an anode flow path 11A, and a cathode-side flow path 200C that communicates with a cathode flow path 11C. The fuel cell 10 has the anode flow path 11A and the cathode flow path 11C. The anode-side flow path 200A communicates with the anode flow path 11A. The cathode-side flow path 200C communicates with the cathode flow path 11C.

[0024] Furthermore, the separation system 1 includes a first separation device 10, a gas-liquid separator 20, a second separation device 30, a water electrolysis device 40, a humidifier 50, a first storage container (raw material fluid supply means, tank) 60, a second storage container 70, a third storage container 80, two supply paths 90A and 90B, two return paths 100A and 100B, a control unit 140, a cathode-side condensation separator (condensation separator) 220, and a first The nitrogen supply flow path (cathode supply flow path) 221, a second nitrogen supply flow path (cathode supply flow path) 222, a cathode off-gas circulation flow path 224, a first pressure detection means 231, a second pressure detection means 232, a compressor 240, a humidifier 250, a cathode gas supply means 260, a nitrogen gas supply flow path 261, a third storage container 270, a concentration power generation means 290, and an adjustment means 300.

[0025] In the anode-side flow path 200A, the water electrolyzer 40, the humidifier 50, the first separator 10, the gas-liquid separator 20, and the second separator 30 are connected in this order from the upstream side by a hydrogen supply flow path 120. In addition, the water electrolyzer 40, the humidifier 50, and the first separator 10 or the second separator 30 are connected in this order from the upstream side by an oxygen supply flow path 130.

[0026] In the cathode side flow path 200C, the cathode gas supply means 260, the humidifier 250, the first pressure detection means 231, the first separation device 10, the cathode side condensation separator (condensation separator) 220, the second pressure detection means 232, and the compressor 240 are connected, in this order from the upstream side, by the nitrogen gas supply flow path 261, the first nitrogen supply flow path 221, the second nitrogen supply flow path 222, the first outflow flow path 223, and the sawed-off gas circulation flow path 224.

[0027] <First Separation Device> The first separation device 10 is a device into which a fluid containing hydrogen isotopes (hereinafter also referred to as the "first fluid") from the anode side flow path 200A and a sixtieth fluid (carrier gas) from the cathode side flow path 200C flow in, and from which a fluid having a lower hydrogen isotope content than the first fluid (hereinafter also referred to as the "second fluid") and a fluid having a higher hydrogen isotope content than the first fluid (hereinafter also referred to as the "sixth fluid") flow out. The first separation device 10 includes a first fuel cell 11. The first separation device 10 includes a temperature control device 301.

[0028] The first fuel cell 11 is for separating hydrogen isotopes from the first fluid in the anode side flow path 200A. A known fuel cell can be used as the first fuel cell 11. As a specific example, the first fuel cell 11 includes an electrolyte membrane (ion exchange membrane), and an anode catalyst layer and an anode flow channel 11A are provided in this order on a first surface of the electrolyte membrane, and a cathode catalyst layer and a cathode flow channel 11C are provided in this order on a second surface. The first fuel cell 11 also includes a pair of separators that sandwich the electrolyte membrane, the anode catalyst layer and the anode flow channel 11A, and the cathode catalyst layer and the cathode flow channel 11C.

[0029] The electrolyte membrane contains an electrolyte, and when the first separation device 10 is operated, hydrogen and hydrogen isotopes contained in the first fluid diffuse from the anode catalyst layer to the cathode catalyst layer through the electrolyte membrane. The electrolyte membrane is not particularly limited as long as it has an electrolyte, but a solid polymer membrane is preferred because it allows hydrogen and hydrogen isotopes to diffuse easily, making it easier for isotope exchange reactions (HD+HO⇔H+HDO, HT+HO⇔H+HTO) to occur at the interface between the electrolyte membrane and the cathode catalyst layer, and improving reaction efficiency. Examples of the solid polymer membrane include a proton-conductive solid polymer membrane and an anion-conductive solid polymer membrane.

[0030] The anode catalyst layer is provided on the first surface of the electrolyte membrane. Examples of catalysts contained in the anode catalyst layer include precious metals such as platinum and ruthenium, transition metals such as nickel and cobalt, and alloys and oxides thereof. Among these, platinum is preferred because it facilitates isotope substitution reactions (H2 + T2 ⇔ 2HT, HT + HO(g) ⇔ HTO(g) + H2) and increases reaction efficiency. The anode flow channel 11A is provided on the surface of the anode catalyst layer opposite the electrolyte membrane, and is a region between the anode catalyst layer and the separator.

[0031] The cathode catalyst layer is provided on the second surface of the electrolyte membrane. Examples of catalysts contained in the cathode catalyst layer include precious metals such as platinum and ruthenium, transition metals such as nickel and cobalt, and alloys and oxides thereof. Among these, platinum is preferred because it facilitates isotope exchange reactions in the cathode catalyst layer and at the interface between the electrolyte membrane and the cathode catalyst layer, thereby increasing the reaction efficiency. In particular, it is preferable that the electrolyte membrane is a solid polymer membrane and that the anode catalyst layer and the cathode catalyst layer contain platinum, since this makes the isotope exchange reaction (N2 + H2O ⇒ HTO + N2 + H2O) more likely to occur and improves the reaction efficiency.

[0032] The cathode flow channel 11C is provided on the surface of the cathode catalyst layer opposite the electrolyte membrane, and is a region between the cathode catalyst layer and the separator. A first outlet flow path 223 is connected to the outlet of the cathode flow path 11C, and allows a sixth fluid (described later) to flow out of the cathode flow path 11C. The first outlet flow path 223 is a third nitrogen supply flow path (cathode discharge flow path) 223. The first outlet flow path (cathode discharge flow path) 223 is connected to a cathode-side condensation separator (condensation separator) 220.

[0033] The separators are provided on the outside of the anode flow channel 11A and the cathode flow channel 11C, respectively. The separator may be made of, for example, styrene, titanium, or carbon.

[0034] The first fuel cell 11 is called a fuel cell, but when the electrolyte membrane, anode catalyst layer, anode flow path, cathode catalyst layer, cathode flow path and separator are considered as one cell (fuel cell), the first fuel cell 11 may be composed of one fuel cell, or may be an assembly of multiple fuel cell cells (fuel cell stack).

[0035] The temperature control device 301 is capable of adjusting the temperature of the first fuel cell 11. Specifically, the temperature control device 301 is, for example, a heat exchanger. The temperature control device 301 can be configured to adjust the temperature of the first fuel cell 11 by flowing a heat medium through a heat pipe arranged inside or outside the first fuel cell 11. The temperature control device 301 can adjust the temperature of the first fuel cell 11 by adjusting the temperature of the heat medium. Alternatively, the temperature control device 301 may be configured to adjust the temperature of the first fuel cell 11 by current control of a Peltier element or the like. The configuration of the temperature control device 301 is not particularly limited. The temperature control device 301 constitutes the adjustment means 300.

[0036] The temperature control device 301 can control the relative humidity of the first fluid flowing through the anode supply flow path 122. In this case, the temperature control device 301 adjusts the dew point of the first fluid. The temperature control device 301 constitutes the adjusting means 300. Furthermore, the temperature control device 301 may be configured to adjust the relative humidity in cooperation with the humidifier 50. The temperature control device 301 constitutes the adjusting means 300. In this case, the temperature control device 301 and the humidifier 50 constitute the adjusting means 300.

[0037] The anode side flow path 200A will be described below.

[0038] <Gas-liquid separator> The gas-liquid separator 20 is provided downstream of the first separation device in the anode-side flow path 200A, and separates the second fluid flowing out from the first separation device into gas and liquid. The gas-liquid separator 20 preferably includes a cooling unit (not shown) that cools the second fluid supplied to the gas-liquid separator 20. A gas-liquid separator that includes a cooling unit is also particularly referred to as a "cooled gas-liquid separator." The second fluid is separated in the gas-liquid separator 20 into a gas (hereinafter also referred to as a "third fluid") and a liquid (hereinafter also referred to as a "fourth fluid").

[0039] <Second Separation Device> The second separation device 30 is provided downstream of the gas-liquid separator 20, and generates power using the gas (third fluid) discharged from the gas-liquid separator 20. In other words, the separation system 1 shown in Fig. 1 also functions as a separation and power generation system. The second separation device 30 includes a second fuel cell 31 and a second outlet flow path 32 .

[0040] The second fuel cell 31 generates electricity and water using the third fluid and oxygen. During the power generation, hydrogen isotopes are separated from the third fluid (HT+1 / 2O2 → HTO). A known fuel cell can be used as the second fuel cell 31. As a specific example, the second fuel cell 31 includes an electrolyte membrane, and an anode catalyst layer and an anode flow path are provided in this order on a first surface of the electrolyte membrane, and a cathode catalyst layer and a cathode flow path are provided in this order on a second surface. The second fuel cell 31 also includes a pair of separators that sandwich the electrolyte membrane, the anode catalyst layer, the anode flow path, and the cathode catalyst layer and the cathode flow path. A second outlet flow path 32 is connected to the outlet of the anode flow path, and allows a seventh fluid (described later) to flow out of the anode flow path.

[0041] The electrolyte membrane, anode catalyst layer, anode flow path, cathode catalyst layer, cathode flow path, and separator constituting the second fuel cell 31 may be similar to the electrolyte membrane, anode catalyst layer, anode flow path, cathode catalyst layer, cathode flow path, and separator constituting the first fuel cell 11 provided in the first separation device 10, respectively. The second fuel cell 31 may be configured as a single fuel cell unit, or may be an assembly of a plurality of fuel cells (fuel cell stack).

[0042] A sealing means may be provided in the second outflow channel 32. The sealing means blocks the outflow of a fluid (a seventh fluid described below) from the anode channel of the second fuel cell 31. Examples of the sealing means include valves such as electromagnetic valves and motor-operated valves.

[0043] The second separation device 30 may further include one or more of a second sealing means (not shown) that seals off the inflow of a fluid (third fluid) into the anode flow path of the second fuel cell 31, a third sealing means (not shown) that seals off the inflow of a fluid (fifth fluid described below) into the cathode flow path of the second fuel cell 31, and a fourth sealing means (not shown) that seals off the outflow of a fluid (eighth fluid described below) from the cathode flow path of the second fuel cell 31. The second sealing means is provided in a fourth hydrogen supply channel 124 (to be described later). The third sealing means is provided in a third oxygen supply channel 133 (to be described later). The fourth sealing means is provided in a second supply channel 90B (to be described later).

[0044] <Water electrolysis device> The water electrolyzer 40 is provided upstream of the first separator 10 in the anode-side flow path 200A, and is a device that electrolyzes water. As the water electrolyzer 40, a known water electrolyzer can be used, such as a solid polymer water electrolyzer or an alkaline water electrolyzer. Among these, an alkaline water electrolyzer is preferred because it can generate a large amount of hydrogen gas. The water electrolyzer 40 can also constitute the adjusting means 300.

[0045] <humidifier> The humidifier 50 is provided between the water electrolyzer 40 and the first separation device 10 in the anode-side flow path 200A, and humidifies the fluids supplied to the first separation device 10 and the second separation device 30. Specifically, the humidifier 50 humidifies a fluid containing hydrogen (hereinafter also referred to as a "first fluid") and a fluid containing oxygen (hereinafter also referred to as a "fifth fluid") out of the hydrogen and oxygen generated by electrolysis of water in the water electrolyzer 40. The fifth fluid humidified by the humidifier 50 is supplied to the cathode flow path 11C of the first fuel cell 11 and the cathode flow path of the second fuel cell 31. The humidifier 50 can also constitute the adjusting means 300. The humidifier 50 is not particularly limited as long as it can generate water vapor. It is preferable that hydrogen and oxygen are not mixed in the humidifier 50 .

[0046] <First Storage Container> The first storage container 60 is connected to the water electrolyzer 40 and is a tank for storing the raw material to be electrolyzed in the water electrolyzer 40 . The first storage container 60 has a raw material supply flow path 61. The raw material supply flow path 61 is a pipe for supplying raw materials to be electrolyzed from the first storage container 60 to the water electrolyzer 40. In other words, the first storage container 60 and the water electrolyzer 40 are connected by the raw material supply flow path 61. One end of the raw material supply flow path 61 is connected to the first storage container 60, and the other end is connected to the water electrolyzer 40. There are no particular limitations on the first storage container 60 as long as it can store the raw material. The raw material stored in the first storage container 60 may be water containing hydrogen isotopes.

[0047] <Second storage container> The second storage container 70 is a tank that stores the liquid (fourth fluid) discharged from the gas-liquid separator 20. There are no particular limitations on the second storage container 70 as long as it can store the fourth fluid.

[0048] <Third Storage Container> The third storage container 80 is a tank that stores the fluid (an eighth fluid, which will be described later) that flows out from the cathode flow channel of the second fuel cell 31. The third storage container 80 is not particularly limited as long as it can store the eighth fluid.

[0049] <Supply route> The supply path 90A is a pipe that supplies the liquid (fourth fluid) discharged from the gas-liquid separator 20 to the second storage container 70. That is, the gas-liquid separator 20 and the second storage container 70 are connected by the supply path 90A. One end of the supply path 90A is connected to the gas-liquid separator 20, and the other end is connected to the second storage container 70. A switching means may be provided midway along the supply path 90A.

[0050] The supply path 90B is a pipe that supplies the fluid (eighth fluid) flowing out from the cathode flow path of the second fuel cell 31 to the third storage container 80. In other words, the second separation device 30 and the third storage container 80 are connected by the supply path 90B. One end of the supply path 90B is connected to the second fuel cell 31, and the other end is connected to the third storage container 80. A switching means may be provided midway along the supply path 90B.

[0051] In the present invention, the supply path 90A that supplies the fourth fluid discharged from the gas-liquid separator 20 to the second storage container 70 is also particularly referred to as the "first supply path 90A." Also, the supply path 90B that supplies the eighth fluid flowing out from the cathode flow path of the second fuel cell 31 to the third storage container 80 is also particularly referred to as the "second supply path 90B."

[0052] <Return path> The return path 100A is a pipe that returns the liquid (fourth fluid) discharged from the gas-liquid separator 20 to the first storage container 60. One end of the return path 100A is connected to the middle of the supply path 90A via the switching means, and the other end is connected to the first storage container 60. When the gas-liquid separator 20 and the return path 100A are connected by the switching means, the gas-liquid separator 20 and the first storage container 60 are connected by the supply path 90A and the return path 100A.

[0053] The return flow path 100B is a pipe that returns the fluid (eighth fluid) flowing out from the cathode flow path of the second fuel cell 31 to the first storage container 60. One end of the return path 100B is connected to a switching means provided midway along the supply path 90B, and the other end joins the return path 100A midway along the return path 100A. When the switching means establishes a connected state between the second separation device 30 and the return path 100B, the second separation device 30 and the first storage container 60 are connected by the supply path 90B, the return path 100B, and the return path 100A.

[0054] In the present invention, the return path 100A, which returns the fourth fluid discharged from the gas-liquid separator 20 to the first storage container 60, is also particularly referred to as the "first return path 100A." Also, the return path 100B, which returns the eighth fluid flowing out from the cathode path of the second fuel cell 31 to the first storage container 60, is also particularly referred to as the "second return path 100B."

[0055] <Hydrogen supply channel> The hydrogen supply flow path 120 is a pipe that connects the water electrolyzer 40, the humidifier 50, the first separator 10, the gas-liquid separator 20, and the second separator 30 in this order from the upstream side of the anode side flow path 200A, and supplies a fluid containing hydrogen isotopes in this order. The hydrogen supply flow path 120 has a first hydrogen supply flow path 121, a second hydrogen supply flow path (anode supply flow path) 122, a third hydrogen supply flow path (anode discharge flow path) 123, a fourth hydrogen supply flow path 124, and a first pump 125.

[0056] The first hydrogen supply flow path 121 is a pipe for supplying a fluid (first fluid) containing hydrogen isotopes generated by electrolysis of water containing hydrogen isotopes in the water electrolyzer 40 from the water electrolyzer 40 to the humidifier 50. That is, the water electrolyzer 40 and the humidifier 50 are connected by the first hydrogen supply flow path 121. The first hydrogen supply flow path 121 constitutes the anode-side flow path 200A.

[0057] The second hydrogen supply flow path 122 is a pipe for supplying the first fluid from the humidifier 50 to the first separation device 10. In other words, the humidifier 50 and the first separation device 10 are connected by the second hydrogen supply flow path 122. One end of the second hydrogen supply flow path 122 is connected to the humidifier 50, and the other end is connected to the inlet of the anode flow path of the first fuel cell 11. The second hydrogen supply flow path 122 constitutes the anode-side flow path 200A.

[0058] The second hydrogen supply channel 122 is provided with a hydrogen concentration measuring means 321 as a hydrogen concentration obtaining means. The hydrogen concentration measuring means 321 measures the hydrogen concentration, described below, in the first fluid flowing through the second hydrogen supply flow path (anode supply flow path) 122. The hydrogen concentration measuring means 321 is connected to the control unit 140. The hydrogen concentration measuring means 321 outputs the hydrogen concentration in the first fluid to the control unit 140. The hydrogen concentration measuring means 321 measures the pressure of the first fluid. The hydrogen concentration measuring means 321 outputs the pressure in the first fluid to the control unit 140.

[0059] The third hydrogen supply flow path 123 is a pipe for supplying a fluid (second fluid) having a lower hydrogen isotope content than the first fluid from the first separation device 10 to the gas-liquid separator 20. In other words, the first separation device 10 and the gas-liquid separator 20 are connected by the third hydrogen supply flow path 123. One end of the third hydrogen supply flow path 123 is connected to the outlet of the anode flow path of the first fuel cell 11, and the other end is connected to the gas-liquid separator 20. The third hydrogen supply flow path 123 constitutes the anode-side flow path 200A.

[0060] The third hydrogen supply flow path 123 is provided with a hydrogen concentration measuring means 322 as a hydrogen concentration obtaining means. The hydrogen concentration measuring means 322 measures the hydrogen concentration, which will be described later, in the second fluid flowing through the third hydrogen supply flow path (anode discharge flow path) 123. The hydrogen concentration measuring means 322 is connected to the control unit 140. The hydrogen concentration measuring means 322 outputs the hydrogen concentration in the second fluid to the control unit 140.

[0061] The third hydrogen supply flow path 123 is provided with an adjustment valve 333 as a hydrogen concentration acquisition means. The adjustment valve 333 is capable of adjusting the flow rate of the second fluid flowing through the third hydrogen supply flow path 123. The adjustment valve 333 is connected to the control unit 140. The opening degree of the adjustment valve 333 can be controlled by the control unit 140. The adjustment valve 333 constitutes the adjustment means 300.

[0062] The fourth hydrogen supply flow path 124 is a pipe for supplying the gas (third fluid) obtained by gas-liquid separation in the gas-liquid separator 20 from the gas-liquid separator 20 to the second separation device 30. In other words, the gas-liquid separator 20 and the second separation device 30 are connected by the fourth hydrogen supply flow path 124. One end of the fourth hydrogen supply flow path 124 is connected to the gas-liquid separator 20, and the other end is connected to the inlet of the anode flow path of the second fuel cell 31. The fourth hydrogen supply flow path 124 constitutes the anode-side flow path 200A.

[0063] The first pump 125 is provided in the first hydrogen supply passage 121 . In addition, since hydrogen is produced in the water electrolysis device 40, the pressure difference at that time causes the fluid to flow downstream. Therefore, it is not always necessary to provide the first pump 125, and the hydrogen supply flow path 120 does not necessarily have to have the first pump 125. The first pump 125 can also constitute the adjustment means 300. The first pump 125, together with the regulating valve 333, is capable of regulating the flow rate of the second fluid flowing through the third hydrogen supply channel 123. In this case, the first pump 125 and the regulating valve 333 constitute the regulating means 300.

[0064] <Oxygen supply channel> The oxygen supply flow path 130 is a pipe that connects the water electrolyzer 40, the humidifier 50, and the first separation device 10 or the second separation device 30 in this order from the upstream side of the anode side flow path 200A, and supplies an oxygen-containing fluid in this order. The oxygen supply channel 130 includes a first oxygen supply channel 131, a second oxygen supply channel 132, a third oxygen supply channel 133, and a second pump 134.

[0065] The first oxygen supply flow path 131 is a pipe for supplying a fluid (fifth fluid) containing oxygen generated by electrolysis of water containing hydrogen isotopes in the water electrolyzer 40 from the water electrolyzer 40 to the humidifier 50. That is, the water electrolyzer 40 and the humidifier 50 are connected by the first oxygen supply flow path 131. The first oxygen supply flow path 131 constitutes the anode-side flow path 200A.

[0066] The second oxygen supply flow path 132 is a pipe for supplying the fifth fluid from the humidifier 50 to the first separation device 10. That is, the humidifier 50 and the first separation device 10 are connected by the second oxygen supply flow path 132. One end of the second oxygen supply flow path 132 is connected to the humidifier 50, and the other end is connected to the inlet of the cathode flow path of the first fuel cell 11. The second oxygen supply flow path 132 constitutes the cathode-side flow path 200C.

[0067] The third oxygen supply flow path 133 is a pipe for supplying the fifth fluid from the humidifier 50 to the second separation device 30. That is, the humidifier 50 and the second separation device 30 are connected by the third oxygen supply flow path 133. One end of the third oxygen supply flow path 133 is connected to the humidifier 50, and the other end is connected to the inlet of the cathode flow path of the second fuel cell 31. The third oxygen supply flow path 133 constitutes the anode side flow path 200A.

[0068] The second pump 134 is provided in the first oxygen supply flow path 131. The second pump 134 can also constitute the adjusting means 300. In addition, oxygen is generated in the water electrolysis device 40, and the resulting pressure difference causes the fluid to flow downstream. Therefore, it is not always necessary to provide the second pump 134, and the oxygen supply flow path 130 does not necessarily have to have the second pump 134.

[0069] <Control unit> The control unit 140 is connected to the first separation device 10, the gas-liquid separator 20, the second separation device 30, the sealing means 33, the water electrolysis device 40, the switching means for the supply channels 90A and 90B, the first pump 125, the second pump 134, the adjustment valve 333, and the temperature control device 301 in the anode side flow path 200A, and controls the operation of these devices. The control unit 140 is connected to the hydrogen concentration measuring means 321 and the hydrogen concentration measuring means 322 in the anode side flow path 200A, and receives the measurement results thereof.

[0070] When stopping the operation of the separation system 1, the control unit 140 causes the switching means of the supply path 90A to establish a connection state in which the gas-liquid separator 20 and the return path 100A are connected. In this connection state, it is preferable to further cause the switching means of the supply path 90B to establish a connection state in which the second separation device 30 and the return path 100B are connected. In addition, when stopping the operation of the separation system 1, the control unit 140 uses the switching means of the supply path 90A to connect the gas-liquid separator 20 and the return path 100A, then stops the first separation device 10 and operates the second separation device 30 so that the amount of power generated by the second separation device 30 is reduced.

[0071] In addition, when the control unit 140 stops the operation of the separation system 1, it closes the sealing means of the second outflow flow path 32 and operates the second separation device 30 so that the anode side across the electrolyte membrane of the second separation device 30 is at a lower pressure than the cathode side. Furthermore, when stopping the operation of the separation system 1, the control unit 140 operates the second separation device 30 so that the amount of current during power generation is lower than the power generation state before the second separation device 30 was stopped. Furthermore, when stopping the operation of the separation system 1, the control unit 140 stops the second separation device 30 after the anode side of the second separation device 30 becomes lower in pressure than the cathode side.

[0072] In addition, when the separation system 1 is operating, the control unit 140 cools the second fluid supplied to the gas-liquid separator 20 using a cooling unit (not shown), and when the operation of the separation system 1 is stopped, the control unit 140 stops cooling the second fluid using the cooling unit after the first separation device 10 and the second separation device 30 have stopped.

[0073] Next, the cathode flow path 200C will be described.

[0074] <Condenser separator> The cathode-side condensation separator (condensation separator) 220 is provided downstream of the first separator 10 in the cathode-side flow path 200C, and separates the sixth fluid flowing out from the first separator 10 into gas and liquid. The cathode-side condensation separator 220 is connected to the first separator 10 via a first outlet flow path (cathode discharge flow path) 223. The cathode-side condensation separator 220 can have a configuration equivalent to that of the gas-liquid separator 20. The cathode-side condensation separator 220 preferably includes a cooling unit (not shown) that cools the sixth fluid supplied to the cathode-side condensation separator 220. A gas-liquid separator including a cooling unit is also particularly referred to as a "cooling gas-liquid separator." The sixth fluid is separated in the cathode-side condensation separator 220 into a gas (hereinafter also referred to as a "sixth first fluid") and a liquid (hereinafter also referred to as a "sixth second fluid").

[0075] The concentration power generation means 290, like the second separation device 30, is provided downstream of the cathode-side condensation separator 220 and is a device that concentrates and separates the liquid (sixth second fluid) discharged from the cathode-side condensation separator 220. Like the second separation device 30, the concentration power generation means 290 may generate power in addition to concentrating and separating the liquid (sixth second fluid) discharged from the cathode-side condensation separator 220. Furthermore, the concentration power generation means 290 may be provided with a device corresponding to the second separation device 30, as well as multiple stages of components corresponding to the gas-liquid separator 20 and the second separation device 30. The concentration power generation means 290 is connected to the cathode-side condensation separator 220 via a third supply path 90C. The third supply path 90C sends the sixth second fluid to the concentration power generation means 290.

[0076] The concentration power generation means 290 may be connected to the third storage container 270 via the third outlet passage 233. The third storage container 270 has functions corresponding to the second storage container 70 and the third storage container 80. The concentration power generation means 290 may be connected to the first storage container 60 via a third return path 100C. The third return path 100C has a function corresponding to the return paths 100A and 100B. The third outlet path 233, the third supply path 90C, and the third return path 100C may be provided with sealing means.

[0077] A cathode off-gas circulation passage 224 is connected to the cathode-side condensation separator 220. To the cathode off-gas circulation passage 224, gas (the sixth fluid) is sent from the cathode-side condensation separator 220.

[0078] <Cathode gas supply means> The cathode gas supply means 260 is provided upstream of the first separation device 10 in the cathode-side flow path 200C, and is a device for storing a carrier gas to be supplied to the first separation device 10. The carrier gas is, for example, an inert gas such as nitrogen gas. Other inert gases may also be air or oxygen. The cathode gas supply means 260 has a nitrogen gas supply passage 261. 261 is a pipe for supplying a carrier gas to the first separation device 10 via an MFC (mass flow controller) 262. One end of the nitrogen gas supply passage 261 is connected to the cathode gas supply means 260, and the other end of the nitrogen gas supply passage 261 is connected to a first nitrogen supply passage 221 via the MFC (mass flow controller) 262. The first nitrogen supply passage 221 is connected to a second nitrogen supply passage (cathode supply passage) 222 via a humidifier 250. The cathode gas supply means 260 and the MFC 262 constitute an adjustment means 300.

[0079] The humidifier 250 has a function corresponding to that of the humidifier 50. The humidifier 250 is provided between the cathode gas supply means 260 and the first separation device 10. The humidifier 250 humidifies a fluid (carrier gas) supplied to the first separation device 10. Specifically, the humidifier 250 humidifies a fluid (60th fluid) containing nitrogen supplied from the cathode gas supply means 260. The 60th fluid humidified by the humidifier 250 is supplied to the cathode flow path 11C of the first fuel cell 11.

[0080] A cathode off-gas circulation flow path 224 is connected to the first nitrogen supply flow path 221 at a connection point 225 located upstream of the humidifier 250. The second nitrogen supply flow path (cathode supply flow path) 222 is connected to the first separation device 10 via a first pressure detection means 231. A second pressure detection means 232 is connected to the cathode offgas circulation flow path 224 downstream of the cathode-side condensation separator 220. A compressor 240 is connected to the cathode offgas circulation flow path 224 downstream of the second pressure detection means 232. The cathode offgas circulation flow path 224 is connected to a connection part 225 on the downstream side of the compressor 240.

[0081] The first pressure detection means 231 detects the pressure of the fluid (60th fluid) supplied to the first separation device 10. The second pressure detection means 232 detects the pressure of the fluid (sixth fluid) discharged from the first separation device 10. The first pressure detection means 231 , the second pressure detection means 232 , and the compressor 240 may constitute the adjustment means 300 .

[0082] <Nitrogen supply and circulation flow path> The cathode-side flow path 200C is a nitrogen supply / circulation flow path. The nitrogen supply / circulation flow path is a pipe that connects the cathode gas supply means 260, the MFC 262, the humidifier 250, the first pressure detection means 231, the first separator 10, the cathode-side condensation separator 220, the second pressure detection means 232, and the compressor 240 in this order from the upstream side of the cathode-side flow path 200C, and supplies and circulates a fluid containing nitrogen gas as a carrier gas in this order. The nitrogen supply / circulation channel has a nitrogen gas supply channel 261 , a first nitrogen supply channel 221 , a second nitrogen supply channel (cathode supply channel) 222 , a third outlet channel 233 , and a cathode off-gas circulation channel 224 .

[0083] The nitrogen gas supply passage 261 is a pipe for supplying nitrogen gas, which is a carrier gas, from the cathode gas supply means 260 to the MFC 262. That is, the cathode gas supply means 260 and the MFC 262 are connected by the nitrogen gas supply passage 261. The first nitrogen supply flow path 221 is a pipe for supplying nitrogen gas, which is a carrier gas, from the MFC 262 to the humidifier 250. The MFC 262 and the humidifier 250 are connected by the first nitrogen supply flow path 221. At the same time, the first nitrogen supply passage 221 is a pipe for supplying the carrier gas returned by the cathode off-gas circulation passage 224 to a connection portion 225 between the MFC 262 and the humidifier 250 for reuse. The cathode off-gas circulation passage 224 is connected to the first nitrogen supply passage 221 at the connection portion 225.

[0084] The second nitrogen supply flow path (cathode supply flow path) 222 is a pipe for supplying the sixtieth fluid from the humidifier 250 to the first separation device 10. That is, the humidifier 250 and the first separation device 10 are connected by the second nitrogen supply flow path (cathode supply flow path) 222. One end of the second nitrogen supply flow path (cathode supply flow path) 222 is connected to the humidifier 250, and the other end is connected to the inlet of the cathode flow path 11C of the first fuel cell 11. At the same time, the second nitrogen supply flow path (cathode supply flow path) 222 has a first pressure detection means 231 between the humidifier 250 and the first separation device 10. The first pressure detection means 231 detects the pressure of the fluid (60th fluid) supplied from the humidifier 250 to the first separation device 10.

[0085] The third outlet flow path 233 is a pipe for supplying a fluid (sixth fluid) having a higher hydrogen isotope content than the first fluid from the first separation device 10 to the cathode condensation separator 220. That is, the first separation device 10 and the cathode condensation separator 220 are connected by the third outlet flow path 233. One end of the third outlet flow path 233 is connected to the outlet of the cathode flow path 11C of the first fuel cell 11, and the other end is connected to the cathode condensation separator 220.

[0086] The cathode off-gas circulation flow path 224 is a pipe for returning and reusing the cathode-side exhaust gas containing a carrier gas from the cathode-side condensation separator 220 to the connection part 225. One end of the cathode off-gas circulation flow path 224 is connected to the cathode-side condensation separator 220, and the other end is connected to the connection part 225 of the first nitrogen supply flow path 221. A compressor 240 is connected to the cathode off-gas circulation passage 224 near the connection part 225. The cathode off-gas circulation passage 224 has a second pressure detection means 232 located closer to the cathode-side condensation separator 220 than the compressor 240. The second pressure detection means 232 detects the pressure of the fluid (first fluid) discharged from the cathode-side condensation separator 220. It is possible not to provide the nitrogen circulation configuration for the cathode off-gas circulation flow path 224.

[0087] <Control unit> The control unit 140 is connected to the cathode gas supply means 260, the first separation device 10, the cathode side condensation separator 220, the compressor 240, the MFC 262, the first pressure detection means 231, the second pressure detection means 232, and the concentration power generation means 290 in the cathode side flow path 200C, and controls the operation of these elements. The control unit 140 receives a first detection value, which is a pressure value detected in the second nitrogen supply channel (cathode supply channel) 222, from the first pressure detection means 231. The control unit 140 receives a second detection value, which is a pressure value detected in the cathode off-gas circulation channel 224, from the second pressure detection means 232.

[0088] The control unit 140 operates the compressor 240 when the detection value of the first pressure detection means 231 is higher than a first predetermined value during the separation operation in the separation system 1. The control unit 140 stops the supply of carrier gas from the cathode gas supply means 260 when the detection value of the first pressure detection means 231 is higher than a predetermined value during the separation operation in the separation system 1. When the supply of carrier gas from the cathode gas supply means 260 is stopped and the detection value of the first pressure detection means 231 is lower than a predetermined value set in advance, the control unit 140 starts the supply of carrier gas from the cathode gas supply means 260.

[0089] The control unit 140 receives the flow rate of the second nitrogen supply channel (cathode supply channel) 222 from the detection value of the first pressure detection means 231 and the detection value of the second pressure detection means 232 during the separation operation in the separation system 1. For detecting the flow rate of the second nitrogen supply channel (cathode supply channel) 222, only one of the first pressure detection means 231 and the second pressure detection means 232 may be provided.

[0090] <Separation system operation> An example of a separation method using the separation system 1 will be described below. First, water containing, for example, hydrogen isotopes is electrolyzed in the water electrolyzer 40. The fluid (first fluid) containing hydrogen isotopes obtained by this electrolysis is introduced into the inlet of the anode flow path 11A of the first fuel cell 11 in the first separation device 10. At this time, the hydrogen concentration in the first fluid is measured by the hydrogen concentration measurement means 321. That is, the hydrogen concentration measurement means 321 measures the concentration ratio of the hydrogen isotope Tb to the proton Hb in the anode supply flow path 122 as the hydrogen concentration in the first fluid. The first fluid may be passed through a humidifier 50 before being introduced into the anode flow path of the first fuel cell 11, or may be introduced directly from the water electrolyzer 40 into the anode flow path of the first fuel cell 11.

[0091] Separately, a fluid (fifth fluid) containing oxygen obtained by electrolysis is introduced into the cathode flow path 11C of the first fuel cell 11 in the first separation device 10 from the inlet. At this time, it is preferable to humidify the fifth fluid in a humidifier 50 before introducing it into the cathode flow path 11C of the first fuel cell 11. In this case, the fifth fluid contains oxygen and water vapor. At the same time, nitrogen gas, which is a carrier gas from the cathode gas supply means 260, flows as the 60th fluid from the inlet of the cathode flow path 11C of the first fuel cell 11 in the first separation device 10. At this time, it is preferable to humidify the 60th fluid in the humidifier 250 before allowing it to flow into the cathode flow path 11C of the first fuel cell 11. The flow rate of N2 (nitrogen gas) is controlled by the MFC 262. At the same time, the first pressure detection means 231 detects the pressure value in the second nitrogen supply flow path (cathode supply flow path) 222 and sends the detected value to the control unit 140.

[0092] In the first separation device 10, some of the hydrogen and hydrogen isotopes contained in the first fluid that has flowed into the anode flow path 11A migrate from the anode flow path 11A to the anode catalyst layer, and then from the anode catalyst layer, pass through the electrolyte membrane, and migrate to the cathode catalyst layer. The protons and hydrogen isotopes that have migrated to the cathode catalyst layer undergo an isotope exchange reaction with water vapor (HO) contained in the fifth fluid that has migrated from the cathode flow channel 11C to the cathode catalyst layer, in the cathode catalyst layer and at the interface between the electrolyte membrane and the cathode catalyst layer, to produce HT and HTO. The protons and hydrogen isotopes contained in the first fluid that do not migrate to the cathode catalyst layer are discharged from the outlet of the anode flow channel 11A as a second fluid, which is a fluid having a lower hydrogen isotope content than the first fluid. The isotope exchange reaction also occurs on the surface of the anode catalyst layer. At this time, the hydrogen concentration in the second fluid is measured by the hydrogen concentration measuring means 322. That is, the hydrogen concentration measuring means 322 measures the concentration ratio of the hydrogen isotope Ta to the proton Ha in the anode discharge flow path 123 as the hydrogen concentration in the second fluid.

[0093] The fifth fluid, which includes the carrier gas that passes through the cathode flow path of the first fuel cell 11 without being used in the above-mentioned isotope exchange reaction, and the TO, HTO, H, and N that are produced by the isotope exchange reaction (HT+HO⇒HTO+H) and move to the cathode flow path, are discharged as a fluid (hereinafter also referred to as the "sixth fluid") from the outlet of the cathode flow path of the first fuel cell 11. The sixth fluid flowing out from the cathode flow path 11C of the first fuel cell 11 is separated into gas and liquid by the cathode side condensation separator 220, and the gas flows out to the cathode off-gas circulation flow path 224 as a sixth first fluid, and the liquid flows out to the third supply path 90C as a sixth second fluid.

[0094] The sixth-first fluid flowing out from the cathode-side condensation separator 220 is returned to the first nitrogen supply channel 221 from the connection part 225 through the cathode offgas circulation channel 224 and reused. At this time, the compressor 240 can be operated to actively return the sixth-first fluid. The sixth-first fluid returned through the cathode offgas circulation channel 224 is mixed with the carrier gas supplied from the cathode gas supply means 260 to become the sixth fluid, which is then supplied again to the first separation device 10. In the cathode offgas circulation channel 224, the pressure is detected by the second pressure detection means 232, and the detected value is sent to the control unit 140. A portion of the sixth second fluid flowing out of the cathode-side condensation separator 220 may be returned to the anode flow path of the first fuel cell 11, or all of it may be supplied to the concentration power generation means 290 and used for power generation in the concentration power generation means 290. If the sixth second fluid is used for power generation, the protons and hydrogen isotopes contained in the sixth second fluid can be consumed. The sixth second fluid may be stored in the third storage container 270.

[0095] A part of the second fluid that flows out from the anode flow path of the first fuel cell 11 may be returned to the anode flow path of the first fuel cell 11, or the whole may be supplied to the gas-liquid separator 20 and used for power generation after being separated into gas and liquid in the gas-liquid separator 20. If the second fluid is used for power generation after being separated into gas and liquid, the protons and hydrogen isotopes contained in the second fluid can be consumed.

[0096] In the gas-liquid separator 20, the second fluid is separated into a gas (third fluid) and a liquid (fourth fluid). At this time, it is preferable that the control unit 140 operates a cooling unit (not shown) provided in the gas-liquid separator 20 to cool the second fluid supplied to the gas-liquid separator 20 by the cooling unit. Cooling the second fluid promotes gas-liquid separation of the second fluid. Furthermore, the control unit 140 causes the switching means to disconnect the gas-liquid separator 20 from the return path 100A to a disconnected state, and connects the gas-liquid separator 20 to the second storage container 70. The third fluid is supplied to the second separation device 30. Meanwhile, the fourth fluid is stored in the second storage vessel 70 as water containing TO.

[0097] In the second separation device 30 , first, the third fluid supplied from the gas-liquid separator 20 flows into the inlet of the anode flow path of the second fuel cell 31 . Separately, a fifth fluid is introduced into the cathode flow passage of the second fuel cell 31 from the inlet. At this time, it is preferable to humidify the fifth fluid using a humidifier 50 before introducing the fifth fluid into the cathode flow passage of the second fuel cell 31. In this case, the fifth fluid contains oxygen and water vapor. The fifth fluid may also contain nitrogen.

[0098] A portion of the hydrogen and hydrogen isotopes contained in the third fluid that has flowed into the anode flow path of the second fuel cell 31 migrate in the form of ions from the anode flow path to the anode catalyst layer, and then from the anode catalyst layer through the electrolyte membrane to the cathode catalyst layer. The hydrogen ions and hydrogen isotope ions that have migrated to the cathode catalyst layer of the second fuel cell 31 react with oxygen that has migrated from the cathode flow path to the cathode catalyst layer in the cathode catalyst layer and at the interface between the electrolyte membrane and the cathode catalyst layer to produce water (HO and TO). This reaction generates electricity in the second separator 30. In this way, the second fluid flowing out from the anode flow channel of the first fuel cell 11 is used for power generation after gas-liquid separation and is consumed.

[0099] The fluid (hereinafter also referred to as the "seventh fluid") that is not used for power generation and has a lower hydrogen isotope content than the third fluid is discharged from the outlet of the anode flow path of the second fuel cell 31. At this time, the control unit 140 leaves the sealing means in the second outlet flow path 32 open. The discharged seventh fluid may be discharged, or at least a portion of the seventh fluid may be returned to the anode flow path of the second fuel cell 31. Furthermore, the liquid generated on the anode side may be returned to the return flow path 100B.

[0100] Meanwhile, water (HO and TO) produced in the cathode catalyst layer of the second fuel cell 31 or the like and transferred to the cathode flow path flows out as a fluid (hereinafter also referred to as an "eighth fluid") from the outlet of the cathode flow path of the second fuel cell 31. At this time, it is preferable that the control unit 140 use the switching means to disconnect the second separation device 30 from the return flow path 100B and connect the second separation device 30 to the third storage container 80. By keeping the second separation device 30 connected to the third storage container 80, the water (HO and TO) as the eighth fluid flowing out from the cathode flow path of the second fuel cell 31 can be stored in the third storage container 80 as water containing TO. In the present invention, the fluid discharged is appropriately treated after being discharged.

[0101] <Separation method of the separation system> An example of the separation method of the above-described separation system 1 will be described below.

[0102] In the separation method of this embodiment, first, when the separation system 1 is operating, the control unit 140 receives the hydrogen concentration ratio in the anode supply flow path 122 and the concentration ratio in the anode discharge flow path 123 output from the hydrogen concentration acquisition means 321 and the hydrogen concentration acquisition means 322. The control unit 140 calculates the separation coefficient α from these values. α=Tb·Ha / Ta·Hb It is calculated as follows. When the separation system 1 continues to operate for a long time, the separation performance deteriorates due to catalyst deterioration and the like in the first fuel cell 11, and the separation coefficient α decreases. At this time, the control unit 140 controls the adjustment means 300 to adjust the separation coefficient α of the first fuel cell 11 and improve the separation coefficient α of the first fuel cell 11.

[0103] Fig. 2 is a graph showing an example of the separation method of the separation system 1. In Fig. 2, the vertical axis represents the separation factor, and the horizontal axis represents the anode channel flow rate (An flow rate). In Fig. 2, the solid line represents the separation factor corresponding to the flow rate of the fluid flowing through the anode channel 11A in a state where the separation performance has not deteriorated (initial state), and the dashed line represents the separation factor corresponding to the flow rate of the fluid flowing through the anode channel 11A in a state where the separation performance has deteriorated (after operation for a predetermined long period of time).

[0104] <First Method> In this method, as shown in FIG. 2, when the separation coefficient decreases from the initial value α1 to a lower value α2, the separation system 1 adjusts the separation coefficient α of the first fuel cell 11 by using the adjustment valve 333 provided in the anode discharge flow path 123 of the adjustment means 300. Specifically, when the separation coefficient α of the first fuel cell 11 is smaller than a predetermined value, the control unit 140 controls the adjustment valve 333 to reduce the flow rate of the second fluid flowing through the anode discharge flow path 123, thereby reducing the flow rate of the fluid flowing through the anode flow path 11A and improving the separation coefficient α of the first fuel cell 11.

[0105] As a result, when the separation factor of the first fuel cell 11 decreases from the initial value α1 to α2, the flow rate of the fluid flowing through the anode flow path 11A is reduced, increasing the fluid residence time on the anode catalyst and the reaction time, making it easier for isotope substitution reactions (H2 + T2 ⇔ 2HT, HT + HO(g) ⇔ HT0(g) + H2) to occur, thereby increasing reaction efficiency. This changes the separation factor from the initial value α1 to α3 on the left, preventing a decrease in the separation factor and maintaining the same separation factor.

[0106] At this time, in addition to controlling the regulating valve 333, the control unit 140 can also control either or both of the water electrolyzer 40 and the first pump 125 to reduce the flow rate of the fluid flowing through the anode flow path 11A. In this case, either or both of the water electrolyzer 40 and the first pump 125 can constitute the regulating means 300.

[0107] Fig. 3 is a graph showing an example of the separation method of the separation system 1. In Fig. 3, the vertical axis represents the separation factor, and the horizontal axis represents the amount of water vapor in the anode flow channel 11A. In Fig. 3, the solid line represents the separation factor corresponding to the amount of water vapor in the anode flow channel 11A when the separation performance is not deteriorated (initial state), and the dashed line represents the separation factor corresponding to the amount of water vapor in the anode flow channel 11A when the separation performance is deteriorated (after operation for a predetermined long period of time).

[0108] <Second Method> In this method, as shown in FIG. 3, when the separation coefficient of the first fuel cell 11 drops below the initial value α1, the separation system 1 adjusts the separation coefficient α of the first fuel cell 11 using the temperature control device 301 of the adjustment means 300. Specifically, when the separation factor α of the first fuel cell 11 is smaller than a predetermined value, the control unit 140 controls the temperature control device 301 to adjust the temperature of the heat medium, thereby raising the temperature of the first fuel cell 11. By raising the temperature of the first fuel cell 11 with the temperature control device 301, the amount of water vapor in the first fluid increases, thereby increasing the amount of water vapor in the fluid flowing through the anode flow path 11A. This improves the separation factor α. At this time, it is important to simultaneously increase the stack temperature Ts of the first fuel cell 11 and the dew point Td of the first fluid, which is the input gas. Here, the stack temperature Ts means simultaneously increasing the temperature of all the cells, not just a single cell. Also, the dew point Td means the amount of water vapor in the input gas.

[0109] As a result, if the separation factor decreases from its initial value α1, increasing the amount of water vapor in the anode flow path 11A increases the amount of H2O(g) in the isotope substitution reaction (H2 + T2 ⇔ 2HT, HT + H2O(g) ⇔ HT0(g) + H2), making it easier for the isotope substitution reaction to occur and improving the reaction efficiency. This changes the separation factor from the initial value α1 to α4 on the right, preventing a decrease in the separation factor and allowing the same separation factor to be maintained.

[0110] At this time, the control unit 140 can increase the amount of water vapor in the first fluid by controlling not only the temperature control device 301 but also either or both of the water electrolyzer 40 and the first pump 125. In this case, either or both of the water electrolyzer 40 and the first pump 125 can constitute the adjustment means 300.

[0111] Fig. 4 is a graph showing an example of a separation method of the separation system 1. In Fig. 4, the vertical axis represents the separation coefficient, and the horizontal axis represents the amount of water vapor in the cathode flow channel 11C. In Fig. 4, the solid line represents the separation coefficient corresponding to the amount of water vapor in the cathode flow channel 11C in a state where the separation performance has not deteriorated (initial state), and the dashed line represents the separation coefficient corresponding to the amount of water vapor in the cathode flow channel 11C in a state where the separation performance has deteriorated (after operating for a predetermined long period of time).

[0112] 4, when the separation factor of the first fuel cell 11 drops below the initial value α1, the separation system 1 adjusts the temperature of the heat medium using the temperature control device 301 of the adjustment means 300 to raise the temperature of the first fuel cell 11. By raising the temperature of the first fuel cell 11 using the temperature control device 301, the amount of water vapor in the first fluid increases, thereby increasing the amount of water vapor in the fluid flowing through the cathode flow path 11C. This improves the separation factor α. At this time, it is important to simultaneously increase the stack temperature Ts of the first fuel cell 11 and the dew point Td of the first fluid, which is the input gas.

[0113] <Third Method> In this method, similar to the second method, when the separation factor falls below the initial value α1, as shown in FIG. 3, the separation system 1 adjusts the separation factor α using the temperature control device 301 of the adjustment means 300. Specifically, when the separation factor α of the first fuel cell 11 is smaller than a predetermined value, the control unit 140 controls the temperature control device 301 to increase the relative humidity of the fluid flowing through the anode flow path 11A, thereby improving the separation factor α of the first fuel cell 11. At this time, as in the second method, it is important to simultaneously increase the stack temperature Ts of the first fuel cell 11 and the dew point Td of the fluid flowing through the anode flow channel 11A, which is the input gas.

[0114] As a result, if the separation factor decreases from its initial value α1, increasing the relative humidity of the fluid flowing through the anode flow path 11A increases the amount of HO(g) in the isotope substitution reaction (H2 + T2 ⇔ 2HT, HT + HO(g) ⇔ HT0(g) + H2), making it easier for the isotope substitution reaction to occur and improving the reaction efficiency. This changes the separation factor from the initial value α1 to α4 on the right, preventing a decrease in the separation factor and allowing the same separation factor to be maintained.

[0115] At this time, the control unit 140 can increase the amount of water vapor in the first fluid by controlling not only the temperature control device 301 but also either or both of the water electrolyzer 40 and the first pump 125. In this case, either or both of the water electrolyzer 40 and the first pump 125 can constitute the adjustment means 300.

[0116] Fig. 4 is a graph showing an example of a separation method of the separation system 1. In Fig. 4, the vertical axis represents the separation coefficient, and the horizontal axis represents the amount of water vapor in the cathode flow channel 11C. In Fig. 4, the solid line represents the separation coefficient corresponding to the amount of water vapor in the cathode flow channel 11C in a state where the separation performance has not deteriorated (initial state), and the dashed line represents the separation coefficient corresponding to the amount of water vapor in the cathode flow channel 11C in a state where the separation performance has deteriorated (after operating for a predetermined long period of time).

[0117] Furthermore, as a third method, as shown in Figure 4, when the separation coefficient of the first fuel cell 11 drops below the initial value α1, the separation system 1 improves the separation coefficient α by increasing the relative humidity of the fluid flowing through the cathode flow path 11C using the temperature control device 301 of the adjustment means 300. At this time, it is important to simultaneously increase the stack temperature Ts of the first fuel cell 11 and the dew point Td of the first fluid, which is the input gas.

[0118] Fig. 5 is a graph showing an example of a separation method of the separation system 1. In Fig. 5, the vertical axis represents the separation coefficient, and the horizontal axis represents the flow rate (Ca flow rate) in the cathode flow channel 11C. In Fig. 5, the solid line represents the separation coefficient corresponding to the flow rate in the cathode flow channel 11C in a state where the separation performance has not deteriorated (initial state), and the dashed line represents the separation coefficient corresponding to the flow rate in the cathode flow channel 11C in a state where the separation performance has deteriorated (after operating for a predetermined long period of time).

[0119] <Fourth Method> In this method, as shown in FIG. 5, when the separation coefficient of the first fuel cell 11 drops below the initial value α1, the separation system 1 adjusts the separation coefficient α of the first fuel cell 11 by the MFC 262 and / or the compressor 240 of the adjustment means 300. Specifically, when the separation factor α of the first fuel cell 11 is smaller than a predetermined value, the control unit 140 controls the MFC 262 and / or the compressor 240 to increase the flow rate in the cathode flow channel 11C, thereby improving the separation factor α.

[0120] As a result, if the separation factor decreases from the initial value α1, increasing the flow rate of the cathode flow path 11C increases the amount of HO(g) in the isotope substitution reaction (H2 + T2 ⇔ 2HT, HT + HO(g) ⇔ HT0(g) + H2), making it easier for the isotope substitution reaction to occur and improving the reaction efficiency. This changes the separation factor from the initial value α1 to α5 on the right, preventing a decrease in the separation factor and allowing the same separation factor to be maintained.

[0121] At this time, the control unit 140 can increase the flow rate of the cathode flow path 11C by controlling not only the MFC 262 and / or the compressor 240, but also any or all of the water electrolyzer 40, the humidifier 50, and the second pump 134. In this case, any or all of the water electrolyzer 40, the humidifier 50, and the second pump 134 can constitute the adjustment means 300.

[0122] In the separation system and separation method of the present embodiment described above, when the separation factor of the first fuel cell 11 decreases from the initial value α1, the adjustment means 300 employs one or more methods selected from reducing the flow rate in the anode flow channel 11A, increasing the amount of water vapor in the first fuel cell 11, and increasing the flow rate in the cathode flow channel 11C, thereby making it possible to increase the separation factor α of the first fuel cell 11 even when the separation factor α has decreased. This makes it possible to improve the separation factor α of the first fuel cell 11, and to restore the separation performance of hydrogen isotopes in the separation system 1. Therefore, the hydrogen isotopes can be enriched by increasing the content of the hydrogen isotopes in the raw fluid, without reducing the separation efficiency.

[0123] Furthermore, in the present invention, it is also possible to individually select and combine the individual configurations in the above-described embodiments.

[0124] For example, the separation constant α of the first separator 10 can be improved by appropriately selecting and combining the first to fourth methods described above.

[0125] Furthermore, in the separation system 1, the other end of the return channel 100B joins the return channel 100A midway along the return channel 100A, but the return channel 100B may be directly connected to the first storage container 60. Furthermore, the other end of the return channel 100C joins the return channel 100B midway along the return channel 100B, but the return channel 100C may be directly connected to the first storage container 60.

[0126] Furthermore, during operation of the separation system 1, the oxygen-containing fluid (fifth fluid) obtained in the water electrolyzer 40 may be supplied directly from the water electrolyzer 40 to the second separation device 30. Furthermore, although the separation system 1 includes two separation devices in the anode-side flow path 200A, the separation system 1 may include more separation devices. In this case, as long as at least the most upstream separation device of the two or more separation devices in the anode-side flow path 200A is the first separation device 10 and the most downstream separation device is the second separation device 30, the remaining separation devices may be the first separation device 10 or the second separation device 30. In particular, it is more preferable that the second separation device 30 is provided only in the most downstream position in the anode-side flow path 200A. Furthermore, when two or more first separation devices 10 are provided in the anode-side flow path 200A, a gas-liquid separator 20 may be provided between each of the first separation devices 10, or the first separation devices 10 may be connected to each other and a gas-liquid separator 20 may be provided between the rearmost first separation device 10 and the second separation device 30. Furthermore, two or more separation devices may be provided in the cathode-side flow path 200C. [Explanation of symbols]

[0127] 1. Separation system 10...First separation device 11...First fuel cell (fuel cell) 11A...Anode flow path 11C...Cathode flow path 20…Gas-liquid separator 30...Second separation device 40...Water electrolyzer (adjustment means) 50...Humidifier (adjustment means) 60...First storage container (raw material fluid supply means, tank) 70...Second storage container 90C...Supply channel (third supply channel) 100C...Reflux channel (third reflux channel) 122...Second hydrogen supply channel (anode supply channel) 123...Third hydrogen supply channel (anode discharge channel) 125...First pump 132...Second oxygen supply channel (cathode supply channel) 140...Control unit 200A...Anode side flow path 200C: Cathode side flow path 220... Cathode side condensation separator (condensation separator) 222...Second nitrogen supply channel (cathode supply channel) 223...Third nitrogen supply channel (first outlet channel, cathode exhaust channel) 224...Cathode off-gas circulation passage 231...first pressure detection means 232...Second pressure detection means 240...Compressor 250…humidifier 260...Cathode gas supply means (nitrogen gas tank) 261...Nitrogen gas supply channel 262...MFC (cathode supply flow rate control means, adjustment means) 270...Third storage container 290...Concentrated power generation means 300…Adjustment means 301...Temperature control device (adjustment means) 321, 322...Hydrogen concentration measurement means (hydrogen concentration acquisition means) 333...Adjusting valve (adjusting means)

Claims

1. a fuel cell comprising an electrolyte membrane and a catalyst, an anode flow path on the anode side sandwiching the electrolyte membrane, and a cathode flow path on the cathode side sandwiching the electrolyte membrane; an anode discharge flow path and an anode supply flow path communicating with the anode flow path; a cathode discharge flow path and a cathode supply flow path communicating with the cathode flow path; a raw material fluid supply means connected to the anode supply flow path for supplying a raw material fluid containing hydrogen isotopes; a cathode gas supply means connected to the cathode supply flow path for supplying a fluid containing an inert gas; a hydrogen concentration acquisition means for acquiring the hydrogen concentration of a fluid flowing through the anode supply flow channel and the anode discharge flow channel; a separation coefficient α is calculated from the concentration ratio of hydrogen isotope Tb to hydrogen Hb in the anode supply flow path and the concentration ratio of hydrogen isotope Ta to hydrogen Ha in the anode discharge flow path, both of which are output from the hydrogen concentration acquisition means; α=Tb・Ha / Ta・Hb a control unit that calculates the an adjusting means for adjusting the separation factor α under the control of the control unit; having Separation system.

2. the adjusting means includes an adjusting valve provided in the anode exhaust flow path, the control unit reduces the flow rate of the fluid flowing through the anode discharge flow path by the adjustment valve when the separation coefficient α is smaller than a predetermined value. The separation system of claim 1 .

3. the adjusting means includes a temperature control device that controls the temperature of the fuel cell; the control unit increases the temperature of the fuel cell unit using the temperature control device when the separation coefficient α is smaller than a predetermined value; The separation system of claim 1 .

4. the temperature control device is capable of controlling the relative humidity of the fluid flowing through the anode supply flow path; the control unit increases the relative humidity of the fluid flowing through the anode supply flow path by using the temperature control device when the separation coefficient α is smaller than a predetermined value. The separation system of claim 3 .

5. the temperature control device is capable of controlling the relative humidity of the fluid flowing through the cathode supply flow path; the control unit increases the relative humidity of the fluid flowing through the cathode supply flow path by using the temperature control device when the separation coefficient α is smaller than a predetermined value. The separation system of claim 3 .

6. the adjusting means includes a cathode supply flow rate control means that adjusts the flow rate of the fluid flowing through the cathode supply flow path, the control unit increases the flow rate of the fluid flowing through the cathode supply flow path by the cathode supply flow rate control means when the separation coefficient α is smaller than a predetermined value. The separation system of claim 1 .

7. 7. The separation system according to claim 1, wherein when the separation factor α is smaller than a predetermined value, the separation factor α is increased by controlling one or more selected from the flow rate of the fluid flowing through the anode discharge flow path, the temperature of the fuel cell, the relative humidity of the fluid flowing through the anode supply flow path, the flow rate of the fluid flowing through the cathode supply flow path, and the relative humidity of the fluid flowing through the cathode supply flow path. A method for separating hydrogen isotopes.

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