Fuel cell unit

Abstract

To provide a fuel cell unit capable of reducing power generation cost.SOLUTION: In power generation, a control unit 9 controls an on-off valve 8, and a switching valve 7 in either a first control mode where the control unit activates a pump 2 while controlling the on-off valve to transit into a closed state to close a pipe 5w, and controlling the switching valve to connect a suction port 2i of the pump 2 to a gas-liquid separation tank 3, thereby flowing new first gas into a separator 11 by allowing the pump 2 to suck first gas from the separator 11 via the gas-liquid separation tank 3 or a second control mode where the control unit activates the pump 2 while controlling the on-off valve 8 to transit into an open state to open the pipe 5w, and controlling the switching valve 7 to connect an exhaust port 2o of the pump 2 to the gas-liquid separation tank 3, thereby pumping the first gas from the pump 2 to the separator 11 via the gas-liquid separation tank 3 and pumping water separated in the gas-liquid separation tank 3 from the gas-liquid separation tank 3 to a fuel supply device through the pipe 5w.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fuel cell unit configured to generate electricity by reacting a first gas containing an oxidant with a second gas containing hydrogen.

Background Art

[0002] For example, the following patent document discloses an energy supply system (hereinafter, also simply referred to as a "system") configured to utilize hydrogen and oxygen generated in a hospital at a hospital, a hydrogen station, a house, and the like. Specifically, this system includes a power generation unit that generates power (performs solar power generation), a pure water storage unit that stores water (pure water) generated by an electrically regenerative pure water generator, an electrolysis device that electrolyzes water using the power generated in the power generation unit, a hydrogen tank that stores hydrogen obtained in the electrolysis device, an oxygen tank that stores oxygen obtained in the electrolysis device, a fuel cell that generates power using hydrogen, and an oxygen supply device that provides oxygen for oxygen inhalation.

[0003] In this case, the hydrogen generated in the electrolysis device is supplied to a hydrogen station, which is a hydrogen supply facility, and stored in a hydrogen tank, and then supplied from the hydrogen station to the fuel cell and used for power generation. Further, the oxygen generated in the electrolysis device is stored in the oxygen tank of the oxygen supply device and used for medical purposes in the hospital. Thus, in this system, it is possible to effectively utilize oxygen obtained by electrolysis of water by the electrolysis device together with hydrogen.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the system disclosed in the above-mentioned patent document has the following problems that need to be solved.

[0006] Specifically, the system described above employs a configuration in which water (pure water) produced by an electrolytic pure water generator is stored in a pure water storage unit, and the stored water is supplied to an electrolysis unit for electrolysis to obtain hydrogen used for power generation in fuel cells. In this case, the system employs a configuration in which the water (pure water) used as raw material in the electrolysis unit that generates hydrogen for use in fuel cells for power generation is produced by an electrolytic pure water generator. In other words, this system consumes electricity when producing the water needed to obtain the hydrogen required for power generation, which leads to a problem in that the cost of hydrogen production is soaring, making it difficult to reduce power generation costs.

[0007] On the other hand, in the fuel cell system described above, a large amount of water is generated on the cathode electrode side of the membrane electrode assembly when oxygen and hydrogen react during power generation, and this water is discharged from the fuel cell along with the exhaust. Therefore, the applicant attempted a power generation method in which this water discharged along with the exhaust is recovered and used as a raw material for hydrogen production. As a result, compared to the above system configuration in which hydrogen is produced using water produced by an electrically regenerative pure water generator as a raw material, it is possible to reduce the power generation cost (hydrogen production cost) by eliminating the need for electricity to produce the water as a raw material.

[0008] However, in the power generation method attempted by the applicant, the process of transporting the recovered water in a transport container and pouring it into the hydrogen generator is cumbersome. If a liquid transfer pump or similar device is installed to automate this process, electricity will be used to supply water to the hydrogen generator. Therefore, this point needs to be improved in order to use wastewater from the power generation cell as a raw material for hydrogen production.

[0009] This invention has been made in view of the above-mentioned problems, and its main objective is to provide a fuel cell unit that can significantly reduce power generation costs without requiring complicated procedures. [Means for solving the problem]

[0010] To achieve the above objective, the fuel cell unit according to claim 1 comprises a fuel cell body configured to generate electricity by reacting the first gas and the second gas via the membrane electrode assembly, wherein a plurality of flat plate-shaped laminates are stacked and integrated, each including at least a first separator through which a first gas containing an oxidant passes, a second separator through which a second gas containing hydrogen passes, and a membrane electrode assembly disposed between the first separator and the second separator, and the fuel cell body is configured to generate electricity by reacting the first gas and the second gas via the membrane electrode assembly, a pump that supplies the first gas to the first separator, and a pump that electrolyzes the raw material water to produce A fuel cell unit comprising a fuel supply device that generates hydrogen to produce the second gas and supplies the produced second gas to the second separator, the unit comprising a gas-liquid separation tank disposed between the first separator and the pump for separating and recovering water contained in the exhaust gas discharged from the first separator, a connection switching device for selectively connecting either the intake port or exhaust port of the pump to the gas-liquid separation tank, and a first piping for supplying the water separated in the gas-liquid separation tank as the raw material to the fuel supply device, The fuel cell body comprises a first valve mechanism disposed in the first piping, the pump, the connection switching device, and a control unit that controls the first valve mechanism, and when generating power in the fuel cell body, the control unit controls the first valve mechanism to close the first piping, and controls the connection switching device to connect the intake port of the pump to the gas-liquid separation tank, thereby operating the pump and drawing the first gas from the first separator to the pump via the gas-liquid separation tank, thereby generating new first gas The pump operates in either of the following two modes: a first control mode that causes the gas to flow into the first separator, or a second control mode that controls the first valve mechanism to open the first piping and controls the connection switching device to connect the exhaust port of the pump to the gas-liquid separation tank, thereby pressurizing the pump to send the first gas from the pump to the first separator via the gas-liquid separation tank, and pressurizing the water separated in the gas-liquid separation tank to send from the gas-liquid separation tank to the fuel supply device via the first piping.The connection switching device and the first valve mechanism are configured to be controllable.

[0011] Furthermore, the fuel cell unit according to claim 2 is the fuel cell unit according to claim 1, further comprising: a second pipe for supplying the second gas from the fuel supply device to the second separator; a third pipe connecting the exhaust port of the second separator to the gas-liquid separation tank; a second valve mechanism for restricting / allowing the inflow of the first gas into the second pipe; and a third valve mechanism disposed in the third pipe, wherein when the control unit performs control in the first control mode and the second control mode, it controls the second valve mechanism to restrict the inflow of the first gas into the second pipe and controls the third valve mechanism to transition to a closed state that closes the third pipe, and when the fuel cell body is not generating electricity and predetermined conditions are met, the first The pump, the connection switching device, the first valve mechanism, the second valve mechanism, and the third valve mechanism are configured to be controllable in a third control mode in which the first valve mechanism is controlled to transition to the closed state, the second valve mechanism is controlled to allow the inflow of the first gas into the second piping, the third valve mechanism is controlled to transition to the open state in which the third piping is opened, and the connection switching device is controlled to connect the intake port of the pump to the gas-liquid separation tank, and the pump is operated in such a state that the first gas is drawn into the pump from the second separator via the gas-liquid separation tank and the third piping, thereby separating and recovering the water contained in the first gas exhausted from the second separator in the gas-liquid separation tank. [Effects of the Invention]

[0012] In the fuel cell unit according to claim 1, the control unit is configured to control the pump, the connection switching device, and the first valve mechanism in either a first control mode in which, when generating power in the fuel cell body, the control unit controls the first valve mechanism to transition to a closed state in which the first piping is closed, and controls the connection switching device to operate the pump with the intake port of the pump connected to the gas-liquid separation tank, thereby drawing the first gas from the first separator to the pump via the gas-liquid separation tank and allowing new first gas to flow into the first separator; or a second control mode in which the control unit controls the first valve mechanism to transition to an open state in which the first piping is opened, and controls the connection switching device to operate the pump with the exhaust port of the pump connected to the gas-liquid separation tank, thereby pressurizing the first gas from the pump to the first separator via the gas-liquid separation tank and pressurizing the water separated in the gas-liquid separation tank from the gas-liquid separation tank to the fuel supply device via the first piping.

[0013] Therefore, according to the fuel cell unit described in claim 1, unlike a configuration in which water (pure water) used as raw material in an electrolysis device for hydrogen generation is produced by an electrically regenerative pure water generator, by controlling each part in the first control mode, water discharged from the fuel cell body (first separator) during power generation is separated and recovered in a gas-liquid separation tank, and this water can be used as raw material for hydrogen generation in the fuel supply device. Since electricity is not required to generate the raw material water, the cost of hydrogen generation can be sufficiently reduced. Furthermore, by controlling each part in the second control mode, without transporting the recovered water in the gas-liquid separation tank in a transport container or the like and pouring it into the fuel supply device, or by installing a liquid transfer pump to pressurize water from the gas-liquid separation tank to the fuel supply device, the water in the gas-liquid separation tank can be pressurized and sent from the gas-liquid separation tank to the fuel supply device while continuing power generation, thus further reducing the cost of hydrogen generation. As a result, the cost of power generation using the hydrogen produced in the fuel supply device can be sufficiently reduced.

[0014] Furthermore, in the fuel cell unit according to claim 2, when the control unit performs control in the first control mode and the second control mode, it controls the second valve mechanism to restrict the inflow of the first gas into the second piping, and controls the third valve mechanism to transition to a closed state that closes the third piping, and when predetermined conditions are met when the fuel cell body is not generating power, it controls the first valve mechanism to transition to a closed state, controls the second valve mechanism to allow the inflow of the first gas into the second piping, and controls the third valve mechanism The pump, connection switching device, first valve mechanism, second valve mechanism, and third valve mechanism are controlled in a third control mode in which the pump, connection switching device is opened, and the connection switching device is controlled to connect the intake port of the pump to the gas-liquid separation tank, and the pump is operated in this state, thereby drawing the first gas from the second separator to the pump via the gas-liquid separation tank and the third pipe, and separating and recovering the water contained in the first gas exhausted from the second separator in the gas-liquid separation tank.

[0015] Therefore, according to the fuel cell unit described in claim 2, not only can a sufficient amount of water be secured as a raw material in the fuel supply device, but it is also possible to suitably avoid a situation where a large amount of water droplets (liquid phase water) discharged from the fuel supply device along with the second gas generated in the fuel supply device, or water droplets (liquid phase water) generated by condensation, are present in the second separator, thereby preventing the passage resistance of the second gas supplied during power generation from becoming excessively large, and thus enabling suitable power generation in the fuel cell body. [Brief explanation of the drawing]

[0016] [Figure 1] This is a diagram illustrating the configuration of the fuel cell unit 1, and is an explanatory diagram describing an operating mode in which wastewater from the separator 11 is recovered in parallel with power generation in the fuel cell cell 10. [Figure 2] This is an explanatory diagram illustrating an operating mode in which water recovered from the fuel cell cell 10 is supplied to the hydrogen generator 20 in parallel with power generation. [Figure 3]This is an explanatory diagram illustrating an operating mode in which water is recovered from the separator 12 of the fuel cell cell 10 when power generation is not being performed. [Modes for carrying out the invention]

[0017] The following describes embodiments of the fuel supply device and fuel cell unit with reference to the attached drawings.

[0018] The fuel cell unit 1 shown in Figure 1 is an example of a "fuel cell unit" and is configured to generate electricity by reacting gases for power generation (air (atmosphere: oxygen), which is an example of a "first gas containing an oxidizer," and hydrogen gas, which is an example of a "second gas containing hydrogen"). Specifically, the fuel cell unit 1 includes a pump 2, a gas-liquid separation tank 3, a post-treatment device 4, piping 5a-5j, 5w, switching valves 6a-6d, 7, on-off valve 8, a control unit 9, a fuel cell cell 10, and a hydrogen generator 20.

[0019] In this case, the fuel cell cell 10 is an example of a "fuel cell body configured to generate electricity by reacting a first gas and a second gas," and includes a power generation stack consisting of a separator 11, which is an example of a "first separator," a separator 12, which is an example of a "second separator," and an MEA 13, which is an example of a "membrane electrode assembly (fuel cell membrane electrode assembly)," as well as a separator (not shown) for passing a cooling fluid (air or coolant), and end plates (not shown) disposed at both ends in the stacking direction of each stack. In this example, each plate, such as the separators 11, 12, MEA 13, the cooling separator, and the end plates, corresponds to "multiple flat plate-shaped stacked objects," and the fuel cell cell 10 is constructed by stacking and integrating these.

[0020] In addition, the separator 11 is formed with a groove portion (not shown) for allowing air (atmosphere) to pass through, and the separator 12 is formed with a groove portion (not shown) for allowing hydrogen gas to pass through. They are laminated such that the MEA 13 is sandwiched between the two separators 11 and 12. As a result, an air flow path 11c is formed by the groove portion of the separator 11 and one surface of the MEA 13, and the separator 11 functions as an anode (air electrode: oxygen electrode). At the same time, a hydrogen flow path 12c is formed by the groove portion of the separator 12 and the other surface of the MEA 13, and the separator 12 functions as a cathode (hydrogen electrode). The MEA 13 is configured to include an electrolyte membrane, a catalyst layer, a gas diffusion layer, and the like.

[0021] In addition, the actual fuel cell 10 is configured to include a plurality of the above-described power generation stacks and cooling separators according to the power generation capacity required for the fuel cell unit 1. However, only one power generation stack is shown to facilitate the understanding of the configuration and operation of the fuel cell unit 1, and the illustration and description of the cooling separator and end plate are omitted.

[0022] The hydrogen generator 20 is an example of a "fuel supply device" and is configured to generate hydrogen by electrolyzing water as a "raw material" and supply the generated hydrogen (hydrogen gas) as a "second gas: fuel" to the separator 12 of the fuel cell 10. In this case, during power generation in the fuel cell 10, the air (oxygen) passing through the air flow path 11c reacts with the hydrogen gas (hydrogen) passing through the hydrogen flow path 12c to generate water in the air flow path 11c, and this water is discharged from the separator 11 together with the exhaust gas. In addition, due to the fact that the fuel cell 10 (separator 12) is at a low temperature (room temperature) immediately after the start of operation, moisture in the hydrogen gas may condense in the hydrogen flow path 12c by heat exchange with the fuel cell 10 (separator 12), and this water may also be discharged from the separator 12 together with the exhaust gas by heat exchange with the air passing through the air flow path 11c and the refrigerant passing through the cooling separator.

[0023] Furthermore, in the fuel cell unit 1 of this example, which generates electricity in the fuel cell cell 10 using hydrogen (hydrogen gas) produced by electrolysis in the hydrogen generator 20 as fuel, a small amount of water (water that was not electrolyzed) is discharged from the hydrogen generator 20 along with the hydrogen gas. This water may flow into the separator 12 along with the hydrogen gas and be discharged from the separator 12 along with the exhaust. Therefore, in the fuel cell unit 1 of this example, as will be described later, this water is recovered in the gas-liquid separation tank 3, and the recovered water is supplied to the hydrogen generator 20 as "raw material" to generate hydrogen.

[0024] On the other hand, pump 2 is an example of a "pump that supplies the first gas to the first separator," and, in accordance with the control of the control unit 9, it sucks air from the air passage 11c of the separator 11 or pumps air into the air passage 11c (supplies air to the separator 11). As will be described later, in this example, the fuel cell unit 1 employs a configuration in which water recovered from the separator 11 (air passage 11c) by pumping air with this pump 2 is pumped (supplied) to the hydrogen generator 20.

[0025] The gas-liquid separation tank 3 is an example of a "gas-liquid separation tank that separates and recovers water contained in the exhaust gas discharged from the first separator," and as will be described later, it is installed between the separator 11 and the pump 2 so that air flowing from the separator 11 to the pump 2 and air flowing from the pump 2 to the separator 11 in the fuel cell cell 10 can pass through.

[0026] The aftertreatment device 4 consists of a recovery device that removes (recovers) hydrogen contained in the gas exhausted from the separator 12 (exhaust gas containing unreacted hydrogen in the fuel cell cell 10) after it reacts with the air (oxygen) in the air channel 11c in the hydrogen channel 12c of the separator 12, and a mixing device that mixes air (atmosphere) so that the hydrogen concentration of the gas exhausted from the separator 12 falls below a predetermined value (diluting the exhaust gas from the separator 12). Note that this aftertreatment device 4 may be unnecessary when the hydrogen concentration of the exhausted gas is sufficiently low.

[0027] Pipe 5a is connected to the pipe connection 11a of the separator 11, and one end of it is in communication with the atmosphere. Pipe 5b is an example of a "second pipe that supplies a second gas from the fuel supply device to the second separator," and one end is connected to the hydrogen gas outlet of the hydrogen generator 20, and the other end is connected to the pipe connection 12a of the separator 12. Pipe 5c is connected to the pipe connection 11b of the separator 11, and the other end is connected to the gas-liquid separation tank 3. Pipe 5d is connected to the pipe connection 12b of the separator 12, and the other end is connected to the aftertreatment device 4. Pipe 5e is connected to the gas-liquid separation tank 3, and the other end is connected to the switching valve 7. Pipe 5f is connected to the intake port 2i of the pump 2, and the other end is connected to the switching valve 7. One end of pipe 5g is connected to the exhaust port 2o of pump 2, and the other end is connected to the switching valve 7. Pipe 5h is connected to the switching valve 7, and one end of it is in communication with the atmosphere.

[0028] Piping 5i is a pipe that connects pipes 5a and 5b, with one end connected to a switching valve 6a installed in pipe 5a and the other end connected to a switching valve 6c installed in pipe 5b. Piping 5j is a pipe that connects pipes 5c and 5d, with one end connected to a switching valve 6b installed in pipe 5c and the other end connected to a switching valve 6d installed in pipe 5d. In this case, in the fuel cell unit 1 of this example, a "third pipe connecting the exhaust port of the second separator to the gas-liquid separation tank" is formed between the pipe connection part 12b in pipe 5d and the switching valve 6d, the switching valve 6d, pipe 5j, the switching valve 6b, and the switching valve 6b in pipe 5c and the gas-liquid separation tank 3.

[0029] The piping 5w is an example of a "first piping that supplies water separated in the gas-liquid separation tank to the fuel supply device as a raw material," with one end connected to the bottom of the gas-liquid separation tank 3 and the other end connected to the hydrogen generator 20. In this case, the water discharged from the separator 11 along with air and recovered in the gas-liquid separation tank 3 is acidic with a pH of about 2. Also, the water discharged from the hydrogen generator 20 along with hydrogen and recovered in the gas-liquid separation tank, as well as the water generated by condensation in the hydrogen flow path 12c, is acidic with a pH of about 4. Therefore, in the fuel cell unit 1 of this example, an ion exchange treatment device (for example, SO4) is connected to the piping 5w. 2- An anion exchange resin filter (not shown) capable of removing sulfate ions is provided, and prior to supplying this water to the hydrogen generator 20, an ion exchange treatment is performed in an ion exchange treatment device. This configuration prevents deterioration of metal parts and piping within the device and improves the treatment efficiency of the electrolysis treatment in the hydrogen generator 20.

[0030] The switching valve 6a is installed in piping 5a and, as described later, according to the control of the control unit 9, allows / restricts the inflow of air from piping 5a to separator 11 and from separator 11 to piping 5a (passage of air between the installation site of the switching valve 6a in piping 5a and the connection end to the pipe connection 11a), and the inflow of air from the installation site of the switching valve 6a in piping 5a to piping 5i. The switching valve 6b is installed in piping 5c ​​and, as described later, according to the control of the control unit 9, allows / restricts the inflow of air from separator 11 to piping 5c ​​and from piping 5c ​​to separator 11 (passage of air between the connection end to the pipe connection 11b in piping 5c ​​and the installation site of the switching valve 6b), and the inflow of air from piping 5j to the installation site of the switching valve 6b in piping 5c ​​(passage of air between the installation site of the switching valve 6b in piping 5c ​​and the connection end to the gas-liquid separation tank 3).

[0031] The switching valve 6c is installed in the piping 5b and, as described later, according to the control of the control unit 9, allows / restricts the inflow of hydrogen gas into the separator 12 via piping 5b, the inflow of hydrogen gas from the location of the switching valve 6c in piping 5b to piping 5i, and the inflow of air from piping 5i to the location of the switching valve 6c in piping 5b (passage of air between the location of the switching valve 6c in piping 5b and the connection end to the piping connection 12a). The switching valve 6d is installed in piping 5d and, as described later, according to the control of the control unit 9, allows / restricts the inflow of hydrogen gas into the aftertreatment device 4 via piping 5d (passage of hydrogen gas between the location of the switching valve 6d in piping 5d and the connection end to the aftertreatment device 4), the inflow of hydrogen gas from the location of the switching valve 6d in piping 5d to piping 5j, and the inflow of air from the location of the switching valve 6d in piping 5d to piping 5j.

[0032] In this case, in the fuel cell unit 1 of this example, the switching valves 6a and 6c work together to form a "second valve mechanism". Furthermore, in the fuel cell unit 1 of this example, the switching valves 6b and 6d work together to form a "third valve mechanism".

[0033] The switching valve 7 is an example of a "connection switching device that selectively connects either the intake port or exhaust port of the pump to the gas-liquid separation tank," and is configured to switch between a connection configuration in which pipes 5e and 5f are connected and pipes 5g and 5h are connected, as shown in Figures 1 and 3, and a connection configuration in which pipes 5e and 5g are connected and pipes 5f and 5h are connected, as shown in Figure 2. The on-off valve 8 is an example of a "first valve mechanism," and is installed in pipe 5w, and in accordance with the control of the control unit 9, allows / regulates the supply of water from the gas-liquid separation tank 3 to the hydrogen generator 20.

[0034] The control unit 9 provides overall control of the fuel cell unit 1. Specifically, the control unit 9 is an example of a "control unit" and controls the switching valve 7 to selectively connect either the intake port 2i or exhaust port 2o of the pump 2 to the gas-liquid separation tank 3, and also controls the pump 2 to supply air to the fuel cell cell 10. The control unit 9 also controls the hydrogen generator 20 to generate hydrogen gas and supply it to the fuel cell cell 10 (separator 12). Furthermore, the control unit 9 switches the switching valves 6a to 6d and the on / off valve 8 to the open / closed state. The operation control of each part by the control unit 9 will be explained in detail later.

[0035] As described above, this fuel cell unit 1 generates electricity by reacting air (atmosphere: oxygen) and hydrogen produced in the hydrogen generator 20 in the fuel cell cell 10. The hydrogen generator 20 also generates hydrogen by electrolysis using water generated in the fuel cell cell 10 (separator 11) during power generation, water generated during hydrogen production in the hydrogen generator 20 (water discharged along with hydrogen), and water produced in the hydrogen channel 12c due to condensation as "raw materials". Therefore, during initial operation immediately after installation of the fuel cell unit 1, or when starting operation after a long period of inactivity (when there is not a sufficient amount of water in the gas-liquid separation tank 3), water (raw material) necessary to generate the hydrogen required to start power generation is injected into the hydrogen generator 20.

[0036] In this state, when power generation is instructed to start by operating an operation unit (not shown) (an example of "when power generation is performed in the fuel cell body"), the control unit 9 moves the on-off valve 8 to the closed state, as shown in Figure 1 (an example of control that "controls the first valve mechanism to move to a closed state that blocks the first piping"). Furthermore, the control unit 9 controls the switching valve 6a to restrict the inflow of air from the location of the switching valve 6a in piping 5a to piping 5i, and controls the switching valve 6b to restrict the inflow of air from the location of the switching valve 6b in piping 5c ​​to piping 5j, and controls the switching valve 6c to restrict the inflow of hydrogen gas from the location of the switching valve 6c in piping 5b to piping 5i, and controls the switching valve 6d to restrict the inflow of hydrogen gas from the location of the switching valve 6d in piping 5d to piping 5j (an example of control that "controls the second valve mechanism to restrict the inflow of the first gas into the second piping, and controls the third valve mechanism to switch the third piping to a closed state"). In this figure and in Figures 2 and 3 which will be referenced later, ports that have been switched to a closed state in the switching valves 6a, 6d and the on-off valve 8 are shown in black, and ports that have been switched to an open state are shown in white.

[0037] Furthermore, the control unit 9 controls the switching valve 7 to connect the intake port 2i (pipe 5f) of the pump 2 to the gas-liquid separation tank 3 (pipe 5e), and to connect the exhaust port 2o (pipe 5g) to pipe 5h (an example of control that "controls the connection switching device to connect the intake port of the pump to the gas-liquid separation tank"). Next, the control unit 9 controls the pump 2 to start pumping air. At this time, air in the air passage 11c of the fuel cell cell 10 (separator 11) is drawn in from the intake port 2i of the pump 2 via pipe 5f, switching valve 7, pipe 5e, gas-liquid separation tank 3, and pipe 5c, and new air is drawn in (supplied) into the air passage 11c from the pipe connection part 11a via pipe 5a (an example of a "first control mode that causes new first gas to flow into the first separator by drawing the first gas from the first separator to the pump via the gas-liquid separation tank").

[0038] Next, the control unit 9 controls the hydrogen generator 20 to start hydrogen production. In response, the hydrogen generator 20 electrolyzes water as a raw material to produce hydrogen, and the produced hydrogen (hydrogen gas) flows from the pipe connection 12a to the separator 12 via the pipe 5b. As a result, in the fuel cell cell 10, the air (oxygen) passing through the air channel 11c of the separator 11 and the hydrogen gas (hydrogen) passing through the hydrogen channel 12c of the separator 12 react via the MEA 13, generating electricity.

[0039] In this case, as mentioned above, when power is being generated in the fuel cell cell 10, water is generated in the air passage 11c of the separator 11 (on the cathode electrode side of the MEA 13) due to the reaction of oxygen and hydrogen. At this time, the water generated in the air passage 11c is discharged into the pipe 5c from the pipe connection 11b along with the air that has passed through the air passage 11c, and is guided to the gas-liquid separation tank 3. As a result, the air from which water droplets (moisture in the liquid phase) have been separated (water droplets have been removed) is drawn into the pump 2 from the intake port 2i via the pipe 5e, the switching valve 7, and the pipe 5f, exhausted from the exhaust port 2o, and released into the atmosphere via the pipe 5g, the switching valve 7, and the pipe 5h. The water separated from the air is stored in the gas-liquid separation tank 3.

[0040] On the other hand, by continuing power generation in the above state, when a specified amount of water is stored in the gas-liquid separation tank 3, or when the amount of water available as raw material for the hydrogen generator 20 falls below a specified amount, the control unit 9 continues power generation in the fuel cell cell 10 while supplying the water in the gas-liquid separation tank 3 to the hydrogen generator 20 as raw material for hydrogen production. The above condition "when a specified amount of water is stored in the gas-liquid separation tank 3" can be defined as either "when a sufficient amount of water is stored to supply to the hydrogen generator 20 (not so small that it would be necessary to immediately stop the supply after starting)" or "when there is a risk of exceeding the amount that can be stored (there is a risk that the water in the gas-liquid separation tank 3 will be sucked into the pump 2)."

[0041] Here, when any of the above conditions are met, the control unit 9 controls the switching valve 6a to restrict the inflow of air from the location of the switching valve 6a in piping 5a to piping 5i, controls the switching valve 6b to restrict the inflow of air from the location of the switching valve 6b in piping 5c ​​to piping 5j, controls the switching valve 6c to restrict the inflow of hydrogen gas from the location of the switching valve 6c in piping 5b to piping 5i, and controls the switching valve 6d to restrict the inflow of hydrogen gas from the location of the switching valve 6d in piping 5d to piping 5j, as shown in Figure 2, while maintaining this state (another example of the control described as "controlling the second valve mechanism to restrict the inflow of the first gas into the second piping and controlling the third valve mechanism to transition to a closed state that closes the third piping"), and while the pump 2 and hydrogen generator 20 continue to operate, it transitions the on-off valve 8 to an open state (an example of the control described as "controlling the first valve mechanism to transition to an open state that opens the first piping").

[0042] Furthermore, as shown in the figure, the control unit 9 controls the switching valve 7 to connect the exhaust port 2o (pipe 5g) of the pump 2 to the gas-liquid separation tank 3 (pipe 5e), and to connect the intake port 2i (pipe 5f) to pipe 5h (an example of control that "controls the connection switching device to connect the exhaust port of the pump to the gas-liquid separation tank"). In this case, the air drawn into the pump 2 from the intake port 2i via pipe 5h, the switching valve 7, and pipe 5f flows into the fuel cell cell 10 (separator 11) from the pipe connection part 11b via pipe 5g, the switching valve 7, pipe 5e, the gas-liquid separation tank 3, and pipe 5c, passes through the air passage 11c, and is then exhausted from the pipe connection part 11a and released into the atmosphere via pipe 5a. As a result, power generation continues through the reaction between the hydrogen gas (hydrogen) supplied from the hydrogen generator 20 and passing through the hydrogen passage 12c and the air (oxygen) passing through the air passage 11c in the opposite direction to that in the "first control mode" described above.

[0043] Furthermore, as described above, when air pressurized by pump 2 is supplied to the fuel cell cell 10 (separator 11) via the gas-liquid separation tank 3, the inside of the gas-liquid separation tank 3 is pressurized. In this case, the fuel cell unit 1 of this example has a hydrogen generator 20 connected to the vicinity of the bottom of the gas-liquid separation tank 3 (the part where the separated water is collected) via piping 5w. Therefore, the water separated from the air and stored in the gas-liquid separation tank 3 is discharged from the gas-liquid separation tank 3 into piping 5w by the force of the air pressurized into the gas-liquid separation tank 3, and is pressurized and sent to the hydrogen generator 20 without the use of a power source such as a liquid transfer pump (an example of a "second control mode for pressurizing the water separated in the gas-liquid separation tank from the gas-liquid separation tank to the fuel supply device via the first piping").

[0044] As a result, the water discharged from the separator 11 along with the air and stored in the gas-liquid separation tank 3 is supplied to the hydrogen generator 20 as a raw material for generating hydrogen. Furthermore, by continuing to supply water to the hydrogen generator 20, when the amount of water stored in the gas-liquid separation tank 3 falls below a specified amount, the control unit 9 controls each component in the "first control mode" described above. This results in a state where the water generated in the separator 11 is separated and stored in the gas-liquid separation tank 3.

[0045] On the other hand, when hydrogen gas is supplied from the hydrogen generator 20 to the fuel cell cell 10 (separator 12) for power generation, as mentioned above, heat exchange with the fuel cell cell 10 (separator 12), heat exchange with the air passing through the air passage 11c, and heat exchange with the refrigerant passing through the cooling separator can cause moisture in the hydrogen gas to condense in the hydrogen passage 12c, resulting in the formation of water droplets in the hydrogen passage 12c. In addition, a small amount of water (water that has not been electrolyzed) is discharged from the hydrogen generator 20 along with the hydrogen gas, and this water may flow into the separator 12 along with the hydrogen gas. In this case, although the amount of water generated in the hydrogen passage 12c and the amount of water flowing into the hydrogen passage 12c via the piping 5b is less than the amount of water generated in the air passage 11c during power generation, the water droplets (liquid phase moisture) present in the hydrogen passage 12c may create resistance to the passage of hydrogen gas, making it difficult to pass a sufficient amount of hydrogen that should react with air (oxygen).

[0046] Therefore, in the fuel cell unit 1 of this example, as an example, when the termination of power generation is instructed (an example of "when predetermined conditions are met in a state in which the fuel cell body is not generating power"), a configuration is adopted in which the water in the hydrogen channel 12c is discharged from the separator 12 and recovered in the gas-liquid separation tank 3. Specifically, the control unit 9 stops the hydrogen generator 20 while keeping the pump 2 running.

[0047] Next, the control unit 9 moves the on-off valve 8 to the closed state, as shown in Figure 3 (an example of control as "controlling the first valve mechanism to move to the closed state"). The control unit 9 also controls the switching valve 6a to restrict the inflow of air from the piping 5a to the separator 11 (the passage of air between the location of the switching valve 6a in the piping 5a and the end connected to the piping connection 11a), while allowing the inflow of air from the location of the switching valve 6a in the piping 5a to the piping 5i, and controls the switching valve 6c to allow the inflow of air from the piping 5i to the location of the switching valve 6c in the piping 5b (the passage of air between the location of the switching valve 6c in the piping 5b and the end connected to the piping connection 12a).

[0048] Furthermore, as shown in the figure, the control unit 9 controls the switching valve 6d to restrict the inflow of air from the piping 5d to the post-treatment device 4 (the passage of air between the location of the switching valve 6d in the piping 5d and the end connected to the post-treatment device 4), while allowing the inflow of air from the location of the switching valve 6d in the piping 5d to the piping 5j, and controls the switching valve 6b to allow the inflow of air from the piping 5j to the location of the switching valve 6b in the piping 5c ​​(the passage of air between the location of the switching valve 6b in the piping 5c ​​and the end connected to the gas-liquid separation tank 3) (an example of control that "controls the second valve mechanism to allow the inflow of the first gas into the second piping, and controls the third valve mechanism to transition the third piping to an open state").

[0049] Furthermore, the control unit 9 controls the switching valve 7 to connect the intake port 2i (pipe 5f) of the pump 2 to the gas-liquid separation tank 3 (pipe 5e), and to connect the exhaust port 2o (pipe 5g) to pipe 5h (an example of control that "controls the connection switching device to connect the intake port of the pump to the gas-liquid separation tank").

[0050] In this case, gas and water droplets (immediately after switching to operation in this control mode, gas containing a small amount of unreacted hydrogen) in the hydrogen flow path 12c are drawn in via piping 5f, switching valve 7, piping 5e, gas-liquid separation tank 3, and piping 5c, 5j, and 5d. As this gas passes through the gas-liquid separation tank 3, water droplets (moisture in the liquid phase) are separated (water droplets are removed). Subsequently, the gas is drawn into the pump 2 from the intake port 2i via piping 5e, switching valve 7, and piping 5f, and released into the atmosphere via piping 5g, switching valve 7, and piping 5h (an example of a "third control mode in which the first gas is drawn into the pump from the second separator via the gas-liquid separation tank and third piping, thereby separating and recovering the water contained in the first gas exhausted from the second separator in the gas-liquid separation tank").

[0051] Furthermore, when the air in the hydrogen channel 12c is drawn in by the pump 2, air is drawn into the hydrogen channel 12c from the pipe connection 12a via the pipes 5b, 5i, and 5a. Along with this air, the water (liquid phase moisture) in the hydrogen channel 12c is discharged from the separator 12 (pipe connection 12b) and separated from the air in the gas-liquid separation tank 3. Therefore, when each part is operated in the state controlled by this "third control mode," there are no water droplets in the hydrogen channel 12c, and water that can be used as raw material for generating hydrogen in the hydrogen generator 20 is stored in the gas-liquid separation tank 3. As a result, when power generation is performed next (when hydrogen is generated in the hydrogen generator 20), water can be supplied from the gas-liquid separation tank 3 to the hydrogen generator 20 as raw material by controlling each part in the "second control mode" described above.

[0052] Thus, in this fuel cell unit 1, the control unit 9 is configured to control the pump 2, the switching valve 7, and the switching valve 8 in either of the following ways when generating power in the fuel cell cell 10: a "first control mode" in which, when generating power in the fuel cell cell 10, the control unit 9 controls the on-off valve 8 to close the piping 5w and controls the switching valve 7 to connect the intake port 2i of the pump 2 to the gas-liquid separation tank 3, thereby operating the pump 2 and drawing a first gas (air in this example) from the separator 11 to the separator 11 via the gas-liquid separation tank 3, thereby introducing a new first gas into the separator 11; or a "second control mode" in which, when generating power in the fuel cell cell 10, the control unit 9 controls the on-off valve 8 to open the piping 5w and controls the switching valve 7 to connect the exhaust port 2o of the pump 2 to the gas-liquid separation tank 3, thereby pressurizing the pump 2 to send the first gas from the pump 2 to the separator 11 via the gas-liquid separation tank 3, and pressurizing the water separated in the gas-liquid separation tank 3 to the hydrogen generator 20 via the piping 5w.

[0053] Therefore, with this fuel cell unit 1, unlike a configuration in which the water (pure water) used as raw material in the electrolysis device for hydrogen generation is produced by an electrically regenerated pure water generator, by controlling each part in the "first control mode", the water discharged from the fuel cell cell 10 (separator 11) during power generation is separated and recovered in the gas-liquid separation tank 3, and this water can be used as raw material for hydrogen generation in the hydrogen generator 20. Since electricity is not required to generate the raw material water, the cost of hydrogen generation can be significantly reduced. Furthermore, by controlling each part in the "second control mode", the water in the gas-liquid separation tank 3 can be pumped from the gas-liquid separation tank 3 to the hydrogen generator 20 while continuing power generation, without transporting the recovered water in the gas-liquid separation tank 3 in a transport container or the like and pouring it into the hydrogen generator 20, or installing a liquid transfer pump to pressurize the water from the gas-liquid separation tank 3 to the hydrogen generator 20. This further reduces the cost of hydrogen generation. As a result, the cost of power generation using the hydrogen produced in the hydrogen generator 20 can be significantly reduced.

[0054] Furthermore, in this fuel cell unit 1, when the control unit 9 performs control in the "first control mode" and the "second control mode," it controls the switching valves 6a and 6c to restrict the inflow of the first gas into the piping 5b, and controls the switching valves 6b and 6d to transition to a closed state that blocks the piping 5d, 5j, and 5c. When the fuel cell cell 10 is not generating power and a predetermined condition is met (for example, when power generation is instructed to end), it controls the on-off valve 8 to transition to a closed state, and controls the switching valves 6a and 6c to allow the inflow of the first gas into the piping 5b, and In a "third control mode," the pump 2, switching valve 7, on-off valve 8, and switching valves 6a to 6d are controlled so that the switching valves 6b and 6d are moved to an open state, and the switching valve 7 is moved to a state where the intake port 2i of the pump 2 is connected to the gas-liquid separation tank 3, and the pump 2 is operated in this state, thereby drawing the first gas from the separator 12 to the pump 2 via the gas-liquid separation tank 3 and the pipes 5d, 5j, 5c, and separating and recovering the water contained in the first gas exhausted from the separator 12 in the gas-liquid separation tank 3.

[0055] Therefore, with this fuel cell unit 1, not only can a sufficient amount of water be secured for use as raw material in the hydrogen generator 20, but a large amount of water droplets (liquid phase water) discharged from the hydrogen generator 20 along with the hydrogen gas generated in the hydrogen generator 20, as well as water droplets (liquid phase water) generated by condensation, are present in the separator 12 (hydrogen flow path 12c), which can effectively avoid an excessively large resistance to the passage of hydrogen gas supplied during power generation. As a result, power generation can be effectively performed in the fuel cell cell 10.

[0056] The configuration of the "fuel cell unit" is not limited to the example of the configuration of fuel cell unit 1 described above.

[0057] For example, the explanation described a configuration in which water discharged from the hydrogen generator 20 along with hydrogen gas (water separated from hydrogen gas in the gas-liquid separation tank) and water condensed in the hydrogen channel 12c can be used as "raw materials." However, when the amount of water discharged from the hydrogen generator 20 and the amount of water condensed in the hydrogen channel 12c are very small, a configuration can be adopted in which this water is not used as a "raw material." [Explanation of Symbols]

[0058] 1 Fuel cell unit 2 pumps 2i air intake 20 Exhaust port 3 Gas-liquid separation tank 4. Post-processing device 5a~5j,5w Piping 6a~6d Switching valve 7. Switching valve 8. Shut-off valves 9. Control Unit 10 fuel cell cells 11,12 Separator 11a, 11b, 12a, 12b Pipe connection section 11c air passage 12c Hydrogen channel 13 MEA 20 Hydrogen generator

Claims

1. A fuel cell body is configured to generate electricity by reacting the first gas and the second gas via the membrane electrode assembly, comprising a first separator through which a first gas containing an oxidizing agent passes, a second separator through which a second gas containing hydrogen passes, and a plurality of flat plate-shaped laminates, each including at least one of these laminates, stacked and integrated, and the first gas and the second gas being reacted via the membrane electrode assembly. A pump that supplies the first gas to the first separator, A fuel cell unit comprising a fuel supply device that generates hydrogen by electrolyzing raw water to produce the second gas, and supplies the generated second gas to the second separator, A gas-liquid separation tank is disposed between the first separator and the pump to separate and recover water contained in the exhaust gas discharged from the first separator. A connection switching device that selectively connects either the intake port or exhaust port of the pump to the gas-liquid separation tank, A first pipe that supplies the water separated in the gas-liquid separation tank to the fuel supply device as the raw material, A first valve mechanism is provided in the first piping, The system comprises the pump, the connection switching device, and the control unit for controlling the first valve mechanism, The control unit, when generating power in the fuel cell body, A first control mode is to control the first valve mechanism to transition to a closed state that closes the first piping, and to control the connection switching device to connect the intake port of the pump to the gas-liquid separation tank, thereby operating the pump and drawing the first gas from the first separator to the first separator through the gas-liquid separation tank, thereby causing new gas to flow into the first separator. A fuel cell unit configured to control the pump, the connection switching device, and the first valve mechanism in either of the following control modes: a first valve mechanism is controlled to open the first piping, and the connection switching device is controlled to connect the exhaust port of the pump to the gas-liquid separation tank, thereby operating the pump to pump the first gas from the pump to the first separator via the gas-liquid separation tank, and pumping the water separated in the gas-liquid separation tank from the gas-liquid separation tank to the fuel supply device via the first piping.

2. A second pipe for supplying the second gas from the fuel supply device to the second separator, A third pipe connects the exhaust port of the second separator to the gas-liquid separation tank, A second valve mechanism for restricting / allowing the inflow of the first gas into the second piping, The system comprises a third valve mechanism disposed in the third piping, When the control unit performs control in the first control mode and the second control mode, it controls the second valve mechanism to restrict the inflow of the first gas into the second piping, and controls the third valve mechanism to transition to a closed state that blocks the third piping. The fuel cell unit according to claim 1, wherein the pump, the connection switching device, the first valve mechanism, the second valve mechanism, and the third valve mechanism are configured to be controllable in a third control mode, wherein when predetermined conditions are met while the fuel cell body is not generating electricity, the first valve mechanism is controlled to transition to the closed state, the second valve mechanism is controlled to allow the inflow of the first gas into the second piping, and the third valve mechanism is controlled to transition to the open state in which the third piping is opened, and the connection switching device is controlled to connect the intake port of the pump to the gas-liquid separation tank, and the pump is operated in such a state that the first gas is drawn into the pump from the second separator via the gas-liquid separation tank and the third piping, thereby separating and recovering the water contained in the first gas exhausted from the second separator in the gas-liquid separation tank.

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