Fuel cell system capable of flexibly supplying hydrogen

Abstract

The invention provides a fuel cell system capable of flexibly supplying hydrogen, and the fuel cell system comprises an electric pile which is provided with a first gas cavity opening, a second gas cavity opening, a third gas cavity opening and a fourth gas cavity opening; the gas supply device comprises a hydrogen supply device and an oxygen supply device; the reversing device is connected with the hydrogen supply device, the first gas cavity opening and the second gas cavity opening and comprises a first circulation loop and a second circulation loop. The oxygen supply device is connected with the third air cavity opening; the hydrogen supply device can also be connected with the third gas cavity opening and is discharged through the fourth gas cavity opening, and at the moment, the oxygen supply device is disconnected from the third gas cavity opening. Compared with the prior art, multiple different hydrogen input modes are provided, compared with an existing single hydrogen input mode, the matched hydrogen input modes can be selected according to different working conditions or starting strategies, and then different use requirements are met.

Description

Technical Field

[0001] This invention relates to the field of hydrogen fuel cells, and more specifically, to a fuel cell system with flexible hydrogen supply. Background Technology

[0002] Hydrogen fuel cell systems, such as proton exchange membrane fuel cell systems, anion exchange membrane fuel cell systems, phosphoric acid fuel cell systems, and solid oxide fuel cell systems, are power generation systems that use hydrogen as fuel and directly convert chemical energy into electrical energy. Their basic working principle is that hydrogen and oxygen react electrochemically to produce water, electricity, and heat. A typical fuel cell system usually consists of a fuel cell stack, a hydrogen supply subsystem, an air (oxygen) supply subsystem, a thermal management subsystem, and an electronic control module. During operation, hydrogen enters the stack through a fixed anode inlet, flows through the anode flow field, and undergoes a hydrogen oxidation reaction under the action of the anode catalyst. Simultaneously, air (oxygen) enters the stack through a fixed cathode inlet, undergoes an oxygen reduction reaction under the action of the cathode catalyst, and produces water in gaseous or liquid form.

[0003] In current hydrogen fuel cell systems, the gas supply path typically employs a fixed configuration. Specifically, the anode and cathode sides of the stack are equipped with fixed gas inlets and outlets, respectively. Hydrogen enters the stack through the anode inlet, flows through the anode gas chamber, and exits through the anode outlet; air (oxygen) enters through the cathode inlet, flows through the cathode gas chamber, and exits through the cathode outlet.

[0004] This unidirectional, fixed gas supply layout limits the system's adaptability and control flexibility under different operating conditions. For example, in certain specific operating conditions or startup strategies, the fixed gas supply direction may not meet special operational requirements, thus affecting the fuel cell's startup performance or long-term operational life. Summary of the Invention

[0005] The purpose of this invention is to provide a fuel cell system with flexible hydrogen supply, which can achieve flexible hydrogen supply to meet the needs of different specific operating conditions or start-up strategies.

[0006] The embodiments of the present invention are implemented as follows: This application provides a fuel cell system with flexible hydrogen supply, comprising: The fuel cell stack is provided with a first gas chamber and a second gas chamber corresponding to the anode side, and a third gas chamber and a fourth gas chamber corresponding to the cathode side; The gas supply device includes a hydrogen supply device and an oxygen supply device, which are used to supply hydrogen and oxygen-containing gas, respectively; A reversing device, connected to the hydrogen supply device, the first gas port, and the second gas port, includes a first circulation loop and a second circulation loop that can be selectively opened or closed; wherein, when the first circulation loop is open, the hydrogen enters the anode of the fuel cell stack through the first gas port and exits through the second gas port; when the second circulation loop is open, the hydrogen enters the anode of the fuel cell stack through the second gas port and exits through the first gas port. The oxygen supply device is connected to the third gas chamber, so that the oxygen-containing gas enters the cathode of the fuel cell through the third gas chamber and is discharged through the fourth gas chamber. The hydrogen supply device can also be connected to the third gas chamber, so that the hydrogen enters the cathode of the fuel cell through the third gas chamber and is discharged through the fourth gas chamber, and at this time the oxygen supply device is disconnected from the third gas chamber.

[0007] In a possible implementation, the reversing device includes a first pipe, a first control valve, a second pipe, a third pipe, a second control valve, and a fourth pipe; the two ends of the first pipe are respectively connected to the hydrogen supply device and the first port of the first control valve; the two ends of the second pipe are respectively connected to the second port of the first control valve and the first gas chamber port; the two ends of the third pipe are respectively connected to the second gas chamber port and the fourth port of the second control valve; and the two ends of the fourth pipe are respectively connected to the fifth port of the second control valve and the first pipe.

[0008] In a possible implementation, the reversing device further includes a fifth pipe and a sixth pipe; the two ends of the fifth pipe are respectively connected to the third port of the first control valve and the second air chamber port, and the two ends of the sixth pipe are respectively connected to the first air chamber port and the sixth port of the second control valve. In a possible implementation, a hydrogen preheating device is also included, disposed on the first pipe to heat the hydrogen inside the first pipe. In a possible implementation, a circulation pump is also included, located in the fourth conduit, to circulate unreacted hydrogen along the first or second circulation loop. In a possible implementation, a gas-water separator is also included, which is located in the fourth pipeline and upstream of the circulating pump, for separating liquid water carried by the circulating hydrogen.

[0009] In a possible implementation, an exhaust gas treatment device is also included; the gas-liquid separator is also connected to the exhaust gas treatment device via a seventh pipe, the seventh pipe being provided with a third control valve that is intermittently open; the fourth gas chamber is connected to the exhaust gas treatment device via an eighth pipe, the eighth pipe being provided with a fourth control valve that is in a partially open state to maintain a constant pressure of the gas upstream of the fourth control valve.

[0010] In a possible implementation, the oxygen supply device is connected to the third gas chamber via a ninth pipe, which is equipped with a fifth control valve; the hydrogen supply device is connected to the third gas chamber via a tenth pipe; the tenth pipe is equipped with a sixth, a seventh, and an eighth control valve, which are used to control the flow rate, on / off state, and unidirectional flow of hydrogen, respectively; wherein, during the process of inputting oxygen-containing gas through the oxygen supply device, the fifth control valve is opened and the seventh control valve is closed; during the process of inputting hydrogen, the seventh control valve is opened and the fifth control valve is closed.

[0011] In a possible implementation, a thermal management device is also included, connected to the cooling chamber inlet and cooling chamber outlet of the fuel cell stack; it is also connected to the oxygen supply device to heat or cool the oxygen-containing gas.

[0012] The beneficial effects of this invention are as follows: Different hydrogen input methods are provided through the reversing device. Specifically, hydrogen can be introduced into the anode of the fuel cell stack via the first gas chamber through the first circulation loop and discharged through the second gas chamber; or hydrogen can be introduced into the anode of the fuel cell stack via the second gas chamber through the second circulation loop and discharged through the first gas chamber; or hydrogen can be introduced into the cathode via the third gas chamber and discharged through the fourth gas chamber; or hydrogen can be simultaneously introduced into both the anode and cathode. This provides a variety of hydrogen input methods. Compared to existing single hydrogen input methods, a matching hydrogen input method can be selected according to different operating conditions or startup strategies, thereby meeting different usage requirements. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is an overall schematic diagram of an embodiment of the present invention.

[0015] Icons: 1. Fuel cell stack; 101. First gas chamber inlet; 102. Second gas chamber inlet; 103. Third gas chamber inlet; 104. Fourth gas chamber inlet; 105. Cooling chamber inlet; 106. Cooling chamber outlet; 2. Hydrogen supply device; 3. Oxygen supply device; 4. Reversing device; 501. First pipe; 502. Second pipe; 503. Third pipe; 504. Fourth pipe; 505. Fifth pipe; 506. Sixth pipe; 507. Seventh pipe; 508. Eighth pipe; 509 510. Pipeline 9; 511. Pipeline 10; 512. Pipeline 11; 603. First control valve; 604. Second control valve; 605. Third control valve; 606. Fourth control valve; 607. Fifth control valve; 608. Sixth control valve; 609. Seventh control valve; 600. Eighth control valve; 601. Ninth control valve; 7. Hydrogen preheating device; 8. Circulating pump; 9. Electrical control device; 10. Gas-water separator; 11. Tail gas treatment device; 12. Thermal management device. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0018] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0020] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0021] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] Overall, the flexible hydrogen supply fuel cell system in this application embodiment can provide different forms of hydrogen input through the switching device 4. That is, hydrogen can be introduced into the anode of the fuel cell stack 1 through the first circulation loop via the first gas port 101 and discharged through the second gas port 102. Alternatively, hydrogen can be introduced into the anode of the fuel cell stack 1 through the second circulation loop via the second gas port 102 and discharged through the first gas port 101. Hydrogen can also be introduced into the cathode through the third gas port 103 and discharged through the fourth gas port 104. Hydrogen can also be introduced into both the anode and the cathode simultaneously, thus providing a variety of different forms of hydrogen input. Compared with the existing single hydrogen input method, it can select the matching hydrogen input method according to different operating conditions or start-up strategies, thereby meeting different usage requirements.

[0023] refer to Figure 1As shown, the flexible hydrogen supply fuel cell system of this application embodiment includes a fuel cell stack 1, a gas supply device, and a reversing device 4. The anode side of the fuel cell stack 1 is provided with a first gas port 101 and a second gas port 102, and the cathode side of the fuel cell stack 1 is provided with a third gas port 103 and a fourth gas port 104. The gas supply device includes a hydrogen supply device and an oxygen supply device. The hydrogen supply device supplies hydrogen with a certain purity, and the oxygen supply device supplies oxygen-containing gas, which can be air, pure oxygen, or other oxygen-containing mixtures. The reversing device 4 is connected to the hydrogen supply device 2 on one hand, obtaining the initial hydrogen flow and subsequent hydrogen replenishment through the hydrogen supply device 2; on the other hand, it is also connected to the first gas port 101 and the second gas port 102, forming a first circulation loop or a second circulation loop. The hydrogen input methods corresponding to the first circulation loop and the second circulation loop are different, but both can recycle unreacted hydrogen, thereby improving the utilization rate of hydrogen. When the first circulation loop is open, hydrogen enters the anode of the fuel cell stack 1 through the first gas port 101 and exits through the second gas port 102; when the second circulation loop is open, hydrogen enters the anode of the fuel cell stack 1 through the second gas port 102 and exits through the first gas nozzle, thus providing two different forms of hydrogen input.

[0024] Furthermore, the oxygen supply device 3 is connected to the third gas port 103, enabling oxygen-containing gas to be input into the cathode of the fuel cell stack 1 through the third gas port 103 and discharged through the fourth gas port 104. Additionally, the third gas port 103 can also serve as a hydrogen input port, i.e., the hydrogen supply device 2 is connected to the third gas port 103, thereby inputting hydrogen into the cathode of the fuel cell stack 1 through the third gas port and discharging it through the fourth gas port 104. During this process, the connection between the oxygen supply device 3 and the third gas port 103 needs to be disconnected to ensure that only hydrogen is input into the cathode of the fuel cell stack 1. However, in actual engineering practice, in the cathode hydrogen supply mode, although the fifth control valve 605 is closed, a small amount of hydrogen may leak upstream of 605. To prevent hydrogen from further diffusing into the oxygen supply device 3, in the cathode hydrogen supply mode, the ninth control valve 609 is kept open, allowing hydrogen to diffuse out. Furthermore, when switching to the normal operating mode, i.e., when the cathode supplies oxygen-containing gas, a small amount of hydrogen gas in the ninth pipeline 509 can be quickly discharged through the ninth control valve 609. Through the connection between the reversing device 4 and the hydrogen supply device 2 and the third gas chamber port 103, a variety of different hydrogen input methods are provided, which can select different hydrogen input methods according to different operating conditions or start-up strategies, thereby meeting different usage requirements.

[0025] In some embodiments, the reversing device 4 can form a first circulation loop and a second circulation loop by multiple pipes and valve bodies, such as by a combination of multiple pipes, a straight-through valve, or multiple pipes and a three-way valve. The following description uses a three-way valve as an example.

[0026] The reversing device 4 comprises a first pipe 501, a second pipe 502, a third pipe 503, a fourth pipe 504, a fifth pipe 505, a sixth pipe 506, a first control valve 601, and a second control valve 602. Both the first control valve 601 and the second control valve 602 are three-way valves with three ports: the first port, the second port, and the third port of the first control valve 601; and the fourth port, the fifth port, and the sixth port of the second control valve 602. The first pipe 501 is connected at both ends to the hydrogen supply device 2 and the first port, respectively; that is, its inlet end is connected to the hydrogen supply device 2, and its outlet end is connected to the first port. The second pipe 502 is connected at both ends to the second port and the first gas chamber 101, respectively; that is, its inlet end is connected to the second port, and its outlet end is connected to the first gas chamber 101. The third pipe 503 is connected at both ends to the second gas chamber 102 and the fourth port of the second control valve 602, respectively; that is, its inlet end is connected to the second gas chamber 102, and its outlet end is connected to the fourth port. The two ends of the fourth pipe 504 are connected to the fifth port and the first pipe 501, respectively. That is, its inlet end is connected to the fifth port and its outlet end is connected to the first pipe 501. When the first port, second port, fourth port and fifth port are opened, the first circulation loop is formed. At this time, the hydrogen flow direction is: first pipe 501 → first port → inside the first control valve 601 → second port → second pipe 502 → first gas chamber 101 → anode side of fuel cell stack 1 → second gas chamber 102 → third pipe 503 → fourth port → inside the second control valve 602 → fifth port → fourth pipe 504 → first pipe 501.

[0027] Simultaneously, the two ends of the fifth pipe 505 are connected to the third port of the first control valve 601 and the second gas chamber port 102, respectively; that is, its inlet end is connected to the third port and its outlet end is connected to the second gas chamber port 102. The two ends of the sixth pipe 506 are connected to the first gas chamber port 101 and the sixth port of the second control valve 602, respectively; that is, its inlet end is connected to the first gas chamber port 101 and its outlet end is connected to the sixth port. When the first, third, fifth, and sixth control ports are open, and the second and fourth control ports are closed, a second circulation loop is formed. At this time, the hydrogen flow direction is: first pipe 501 → first port → inside the first control valve 601 → third port → fifth pipe 505 → second gas chamber port 102 → anode side of fuel cell stack 1 → first gas chamber port 101 → sixth pipe 506 → sixth port → inside the second control valve 602 → fifth port → fourth pipe 504 → first pipe 501.

[0028] In an optional embodiment, a hydrogen preheating device 7 is provided on the first pipe 501. This device is used to rapidly and accurately preheat the hydrogen that is about to enter the fuel cell stack 1. Especially during cold starts, it ensures that the temperature of the hydrogen entering the fuel cell stack 1 is sufficient to melt ice crystals inside the electrodes without causing excessive water loss from the membrane electrode assembly (MEA), thus reducing the adverse effects of ice crystals inside the electrodes and excessive dryness of the MEA on the lifespan and performance of the fuel cell stack 1. Optionally, the hydrogen preheating device 7 can be a jacketed heater, which can achieve uniform and stable heating of the hydrogen in the first pipe 501, ensuring a stable input hydrogen temperature.

[0029] In an optional embodiment, the first pipe 501 is equipped with a circulation pump 8, which circulates unreacted hydrogen along the first or second circulation loop to improve hydrogen utilization. Optionally, the connection between the fourth pipe 504 and the first pipe 501 is located upstream of the hydrogen preheating device 7, so that the hydrogen circulating to the first pipe 501 via the circulation pump 8 can be heated by the hydrogen preheating device 7, ensuring the consistency of the hydrogen temperature input to the fuel cell stack 1.

[0030] In an optional embodiment, a gas-water separator 10 may also be provided. The gas-water separator 10 is located in the fourth pipe 504 and upstream of the circulating pump 8. It is used to separate the liquid water carried by the circulating hydrogen. The separated hydrogen is then input into the first pipe 501 to participate in the circulation, while the liquid water can be discharged.

[0031] In an optional embodiment, an exhaust gas treatment device 11 may also be provided; the gas-liquid separator 10 is connected to the exhaust gas treatment device 11 through a seventh pipe 507, and the seventh pipe 507 is provided with a third control valve 603 that opens intermittently. When the third control valve 603 is in the open state, under the push of a small amount of hydrogen, the separated liquid water can be discharged into the exhaust gas treatment device 11 through the seventh pipe 507; the fourth gas port 104 is connected to the exhaust gas treatment device 11 through an eighth pipe 508, and the eighth pipe 508 is provided with a fourth control valve 604. The fourth control valve 604 has a constant back pressure function. When it is in the partially open state, it can control the gas pressure on the cathode side of the fuel cell stack 1 to ensure that the gas pressure on the cathode side of the fuel cell stack 1 is within the target setting range.

[0032] In an optional embodiment, the oxygen supply device 3 is connected to the third gas chamber 103 via a ninth pipe 509, which is equipped with a fifth control valve 605; the fifth control valve 605 is opened when oxygen-containing gas is input, and closed when no oxygen-containing gas is input. The hydrogen supply device 2 is connected to the third gas chamber 103 via a tenth pipe 510. The inlet of the tenth pipe 510 is located on the first pipe 501 and connected to the hydrogen supply device 2, and is located downstream of the hydrogen preheating device 7. The tenth pipe 510 is equipped with a sixth control valve 606, a seventh control valve 607, and an eighth control valve 608. The sixth control valve 606 can be a regulating valve to control the flow rate of hydrogen. The seventh control valve 607 can be a control valve to control the on / off of hydrogen. During the process of inputting oxygen-containing gas through the oxygen supply device, it controls the fifth control valve to open and the seventh control valve to close. During the process of inputting hydrogen, it controls the seventh control valve to open and the fifth control valve to close. The eighth control valve 608 can be a check valve to control the unidirectional flow of hydrogen, ensuring that the gas at the third gas chamber port 103 cannot flow into the first pipe 501 through the tenth pipe 510.

[0033] In an optional embodiment, a thermal management device 12 is also provided. The thermal management device 12 is connected to the cooling chamber inlet 105 and cooling chamber outlet 106 of the fuel cell stack 1, thereby exchanging heat with the fuel cell stack 1 to achieve the purpose of controlling the temperature of the fuel cell stack 1. The thermal management device 12 is also connected to the oxygen supply device 3, and heats or cools the oxygen-containing gas through heat exchange to achieve full utilization of heat.

[0034] In an optional embodiment, an eleventh pipe 511 is also provided. The two ends of the eleventh pipe 511 are connected to the eighth pipe 508 and the ninth pipe 509, respectively, and are located downstream of the fourth control valve 604 and upstream of the fifth control valve 605. A ninth control valve 609 is installed on the eleventh pipe 511. When the gas pressure input through the ninth pipe 509 is too high, part of the gas pressure can be relieved by adjusting the ninth control valve 609 to ensure that the gas pressure at the cathode of the fuel cell stack 1 is within the target set range. The ninth control valve 609 also has a diversion function; when the ninth control valve 609 is open, some oxygen-containing gas can be input into the exhaust gas treatment device 11 through the eighth pipe 508, thereby diluting the hydrogen concentration entering the exhaust gas treatment device 11. In an optional embodiment, an electrical control device 9 is also provided to uniformly control the on / off state of each electrical component in the system and the adjustment of each valve body. Optionally, the electrical control device 9 is a PLC.

[0035] The following examples illustrate the hydrogen input methods matched to different operating conditions: Operating Condition 1: This is a normal operating condition. The input method for hydrogen and oxygen-containing gas is the common method. Hydrogen gas is introduced into the anode of fuel cell stack 1 through the first gas port 101 (which functions the same as the anode inlet of a conventional fuel cell stack) and discharged through the second gas port 102 (which functions the same as the anode outlet of a conventional fuel cell stack). That is, hydrogen gas circulates along the first circulation loop. Oxygen-containing gas is introduced into the cathode of fuel cell stack 1 through the third gas port 103 (which functions the same as the cathode inlet of a conventional fuel cell stack) and discharged through the fourth gas port 104 (which functions the same as the cathode outlet of a conventional fuel cell stack). During this process, the introduced hydrogen gas undergoes a hydrogen oxidation reaction under the action of the anode catalyst, and the oxygen gas undergoes an oxygen reduction reaction under the action of the cathode catalyst, generating gaseous or liquid product water.

[0036] Operating Condition 2: This operating condition is used for cold start energy saving and ice melting. In low temperature environments, if ice crystals appear on the anode side of the membrane electrode of fuel cell stack 1, especially at the second gas chamber 102 (i.e., the anode outlet of fuel cell stack 1 in operating condition 1), it will cause corrosion of the membrane electrode of fuel cell stack 1 during the cold start process, affecting the overall lifespan of fuel cell stack 1. Therefore, fuel cell stack 1 needs to be de-iced before power generation. The general practice is to heat the entire fuel cell stack 1 to raise its temperature above zero degrees Celsius to achieve ice melting. However, the overall heating method consumes a lot of energy. To address the high energy consumption issue, the entire fuel cell stack 1 is first heated to a certain temperature (still below zero). Then, circulating hydrogen is supplied in reverse to the anode side of the fuel cell stack 1 through the second gas port 102. Since the hydrogen can be preheated by the hydrogen preheating device 7, the membrane electrode anode side of the fuel cell stack 1 (especially at the second gas port 102) can be heated to above zero temperature, eliminating ice crystals on the membrane electrode anode side of the fuel cell stack 1 (especially at the second gas port 102). At this time, some areas of the fuel cell stack 1 are still below zero. For example, the entire fuel cell stack 1 is first heated to -10°C, and then hydrogen is introduced into the second gas port 102. The preheated hydrogen acts as a heating medium to heat the fuel cell stack 1. At this time, the anode side of the fuel cell stack 1 mainly reaches the above-zero temperature, thereby shortening the heating time, reducing heating energy consumption, and achieving the goal of energy saving.

[0037] Operating Condition 3: This condition involves removing air from the anode and cathode sides of fuel cell stack 1, as well as oxygen molecules adsorbed on the electrode catalyst surface. When fuel cell stack 1 is not in use for a period of time, air will enter its internal anode and cathode sides, and oxygen molecules will adsorb onto the electrode catalyst surface. To quickly remove the air from the anode and cathode sides of fuel cell stack 1 and rapidly eliminate the oxygen molecules adsorbed on the electrode catalyst surface, hydrogen gas is simultaneously introduced into the first gas port 101 and the third gas port 103. This synchronously removes the air from the anode and cathode sides of fuel cell stack 1, and the hydrogen reacts with oxygen on the electrode catalyst surface, rapidly eliminating the oxygen molecules adsorbed on the electrode catalyst surface.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fuel cell system for flexible supply of hydrogen, characterized by, The application relates to a hydrogen-oxygen fuel cell system, which comprises: a stack provided with a first gas cavity port and a second gas cavity port corresponding to an anode side and a third gas cavity port and a fourth gas cavity port corresponding to a cathode side; a gas supply device comprising a hydrogen supply device and an oxygen supply device for supplying hydrogen and oxygen-containing gas respectively; a switching device connected with the hydrogen supply device, the first gas cavity port and the second gas cavity port, comprising a first circulation loop and a second circulation loop which can be selectively opened or closed; when the first circulation loop is in an open state, the hydrogen enters the anode of the stack through the first gas cavity port and is discharged through the second gas cavity port; when the second circulation loop is in an open state, the hydrogen enters the anode of the stack through the second gas cavity port and is discharged through the first gas cavity port; the oxygen supply device is connected with the third gas cavity port so that the oxygen-containing gas enters the cathode of the stack through the third gas cavity port and is discharged through the fourth gas cavity port.

2. The hydrogen-fueled fuel cell system of claim 1, wherein the hydrogen supply device can also be connected with the third gas cavity port so that the hydrogen enters the cathode of the stack through the third gas cavity port and is discharged through the fourth gas cavity port, and at this time, the oxygen supply device is disconnected with the third gas cavity port.

3. The hydrogen-fueled fuel cell system of claim 1, wherein the switching device comprises a first pipeline, a first control valve, a second pipeline, a third pipeline, a second control valve and a fourth pipeline; the two ends of the first pipeline are connected with the hydrogen supply device and a first port of the first control valve respectively, the two ends of the second pipeline are connected with a second port of the first control valve and the first gas cavity port respectively, the two ends of the third pipeline are connected with the second gas cavity port and a fourth port of the second control valve respectively, and the two ends of the fourth pipeline are connected with a fifth port of the second control valve and the first pipeline respectively.

4. The hydrogen-fueled fuel cell system of claim 3, wherein the switching device further comprises a fifth pipeline and a sixth pipeline; the two ends of the fifth pipeline are connected with a third port of the first control valve and the second gas cavity port respectively, and the two ends of the sixth pipeline are connected with the first gas cavity port and a sixth port of the second control valve respectively.

5. The hydrogen-fueled fuel cell system of claim 3 or 4, wherein a hydrogen preheating device is further arranged on the first pipeline to heat the hydrogen in the first pipeline.

6. The hydrogen-fueled fuel cell system of claim 5, wherein a circulating pump is further arranged on the fourth pipeline to make the unreacted hydrogen flow along the first circulation loop or the second circulation loop.

7. The hydrogen-fueled fuel cell system of claim 6, wherein a gas-water separator is further arranged on the fourth pipeline and located upstream of the circulating pump, which is used for separating liquid water carried by the circulating hydrogen.

8. The hydrogen-fueled fuel cell system of claim 7, wherein, a tail gas treatment device is further arranged; the gas-water separator is further connected with the tail gas treatment device through a seventh pipeline, the seventh pipeline is provided with a third control valve which is intermittently opened; the fourth gas cavity port is connected with the tail gas treatment device through an eighth pipeline, the eighth pipeline is provided with a fourth control valve which is in a partially open state to maintain the pressure of the gas upstream of the fourth control valve constant.

9. The hydrogen-fueled fuel cell system of claim 2, wherein, The oxygen supply device is connected with the third air cavity opening through a ninth pipeline, and the ninth pipeline is provided with a fifth control valve; the hydrogen supply device is connected with the third air cavity opening through a tenth pipeline; the tenth pipeline is provided with a sixth control valve, a seventh control valve and an eighth control valve, which are respectively used for controlling the flow, on-off and one-way flow of hydrogen; wherein during the process of inputting the oxygen-containing gas through the oxygen supply device, the fifth control valve is controlled to be opened and the seventh control valve is controlled to be disconnected; during the process of inputting hydrogen, the seventh control valve is controlled to be opened and the fifth control valve is controlled to be disconnected.

10. The hydrogen-fueled fuel cell system of claim 1, wherein, Further comprising a heat management device connected with the cooling cavity inlet and the cooling cavity outlet of the electric pile; and further connected with the oxygen supply device to heat or cool the oxygen-containing gas.

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