A self-circulating fuel cell system

Abstract

The present invention provides a self-circulating fuel cell system, which belongs to the field of fuel cell technology and solves the problem that existing fuel cells are not suitable for use in closed environments. The system includes a fuel cell stack, a hydrogen tank, a control valve, a hydrogen circulation device, a hydrogen-side drain and exhaust valve, an air circulation device, an air-side drain and exhaust valve, an oxygen separation device, and a low-temperature catalytic combustion device. The hydrogen inlet of the fuel cell stack is connected to the gas outlet of the hydrogen tank via the control valve, and is connected to its hydrogen tail gas outlet via the hydrogen circulation device. Its hydrogen tail gas outlet is also connected to the input terminal 1 of the low-temperature catalytic combustion device via the hydrogen-side drain and exhaust valve. The air inlet of the fuel cell stack is introduced into the oxygen-containing mixed gas and is connected to its air tail gas outlet via the air circulation device. Its air tail gas outlet is also connected to the input terminal 2 of the low-temperature catalytic combustion device via the air-side drain and exhaust valve and the oxygen outlet of the oxygen separation device in sequence. By fully treating the hydrogen and oxygen in the tail gas, the safety of the fuel cell in a closed environment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a self-circulating fuel cell system. Background Art

[0002] A fuel cell system is a device that continuously converts the chemical energy of a continuously supplied fuel and oxidant into electrical energy. It typically consists of a fuel cell stack and peripheral components such as hydrogen, air, and cooling equipment. The stack further includes a proton exchange membrane, catalyst layer, gas diffusion layer, and bipolar plates. Because the theoretical voltage of a single cell is 1.23 V, high power output is typically achieved by connecting hundreds of cells in parallel.

[0003] Currently, existing fuel cell systems are primarily used in hydrogen fuel cell vehicles (FCVs), a new energy vehicle with broad development and application prospects, offering numerous advantages such as short refueling times and long driving range.

[0004] However, existing fuel cell systems are not suitable for use in closed environments because they directly discharge hydrogen, oxygen, and nitrogen from the exhaust into the atmosphere. Direct hydrogen discharge poses a safety hazard. Furthermore, in some special environments, direct nitrogen discharge is not possible, requiring further treatment of the nitrogen, hydrogen, and oxygen in the exhaust. Summary of the Invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a self-circulating fuel cell system to solve the problem that existing fuel cells are not suitable for use in closed environments.

[0006] On the one hand, an embodiment of the present invention provides a self-circulating fuel cell system, comprising a fuel cell stack (4), a hydrogen tank (5), a control valve (1), a hydrogen circulation device (2), a hydrogen-side drain and exhaust valve (3), an air circulation device (11), an air-side drain and exhaust valve (6), an oxygen separation device (7), and a low-temperature catalytic combustion device (8); wherein,

[0007] The hydrogen inlet of the fuel cell stack (4) is connected to the gas outlet of the hydrogen tank (5) through the control valve (1), and is connected to its hydrogen tail gas outlet through the hydrogen circulation device (2). The hydrogen tail gas outlet is also connected to the input terminal 1 of the low-temperature catalytic combustion device (8) through the hydrogen side drainage and exhaust valve (3);

[0008] The air inlet of the fuel cell stack (4) is fed with an oxygen-containing mixed gas (i.e., a mixed gas containing oxygen, such as a nitrogen-oxygen mixture), and is connected to its air exhaust outlet via the air circulation device (11). The air exhaust outlet is further connected to the second input terminal of the low-temperature catalytic combustion device (8) via the air-side drain and exhaust valve (6) and the oxygen outlet of the oxygen separation device (7).

[0009] The low-temperature catalytic combustion device (8) is used for fully burning the hydrogen introduced into the first input terminal and the oxygen introduced into the second input terminal (i.e., no residual gas).

[0010] The beneficial effects of the above technical solution are as follows: By adding an oxygen separation device to the tail exhaust device, the oxygen-containing mixed gas discharged from the air side of the fuel cell stack is separated. The separated oxygen and hydrogen discharged from the hydrogen side of the fuel cell stack are fully burned through a low-temperature catalytic combustion device, consuming all the fuel. Nitrogen or other inert gases can be directly discharged into the environment or recovered into a designated gas storage tank. This achieves sufficient treatment of hydrogen and oxygen in the tail gas, improving the safety of the fuel cell system in a closed environment.

[0011] Based on the further improvement of the above system, the oxygen-containing mixed gas is a nitrogen-oxygen mixed gas; the system also includes a pressure pump (14) and a nitrogen tank (9); wherein,

[0012] The nitrogen outlet of the oxygen separation device (7) is connected to the gas inlet of the nitrogen tank (9) after passing through a pressure pump (14);

[0013] The nitrogen tank (9) is used to store nitrogen introduced through the pressure pump (14).

[0014] Furthermore, the self-circulating fuel cell system also includes a controller; wherein,

[0015] The controller is used to open the hydrogen side water discharge and exhaust valve (3) after recognizing that the self-circulating fuel cell system is in a normal operating state, and set the opening duty ratio of the hydrogen side water discharge and exhaust valve (3) to m , and control the hydrogen in the hydrogen tail gas of the fuel cell stack to flow into the low-temperature catalytic combustion device (8); and open the air-side drainage and exhaust valve (6) to separate the nitrogen-oxygen mixed gas on the air side of the fuel cell stack (4) through the oxygen separation device (7), and set the opening duty ratio of the air-side drainage and exhaust valve (6) to k , and controlling the separated oxygen to flow into the low-temperature catalytic combustion device (8), so that the hydrogen and the separated oxygen are fully burned in the low-temperature catalytic combustion device.

[0016] Furthermore, the self-circulating fuel cell system further includes an oxygen tank (10) and a diverter valve (12); wherein,

[0017] The first input end of the diverter valve (12) is connected to the gas outlet of the nitrogen tank (9), the second input end is connected to the gas outlet of the oxygen tank (10), and the output end is connected to the air inlet of the fuel cell stack (4);

[0018] The control ends of the nitrogen tank (9), oxygen tank (10), and diverter valve (12) are all connected to the output end of the controller.

[0019] Furthermore, the self-circulating fuel cell system further includes a first pressure regulating valve (15) and a second pressure regulating valve (16); wherein,

[0020] The control ends of the first pressure regulating valve (15) and the second pressure regulating valve (16) are both connected to the output end of the controller;

[0021] The first input end of the diverter valve (12) is connected to the gas outlet of the nitrogen tank (9) via the first pressure regulating valve (15), and the second input end is connected to the gas outlet of the oxygen tank (10) via the second pressure regulating valve (16).

[0022] Furthermore, the self-circulating fuel cell system further includes a switch valve (13); wherein,

[0023] One end of the switch valve (13) is connected to the gas inlet of the nitrogen tank (9), the other end is connected to the gas outlet of the pressure pump (14), and the control end is connected to the output end of the controller.

[0024] Furthermore, the self-circulating fuel cell system also includes an air compressor; wherein,

[0025] The input end of the air compressor is connected to the output end of the diverter valve (12), the output end is connected to the air inlet of the fuel cell stack (4), and the control end is connected to the output end of the controller;

[0026] The controller is further configured to obtain the gas pressure at the input end of the air compressor; and to adjust the speed of the air compressor according to the gas pressure.

[0027] Furthermore, the controller further comprises:

[0028] A data acquisition unit is used to respectively acquire the gas pressure at the input end of the air compressor, the gas pressure at the inlet of the air circulation device (11), and the output current of the fuel cell (4) in real time, and send them to the data processing and control unit;

[0029] The data processing and control unit is used to start and control the ventilation opening of the hydrogen tank (5), the oxygen tank (10) and the nitrogen tank (9), and adjust the control valve (1) and the diverter valve (12) to reach the set opening according to the required power of the fuel cell system; and start the hydrogen circulation device (2) and the air circulation device (11). After the gas pressure at the inlet of the air circulation device (11) reaches the set pressure, close the input end of the diverter valve (12) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set value; and after identifying that the self-circulating fuel cell system is in a normal operating state according to the output current of the fuel cell stack (4), first open the hydrogen side drainage and exhaust valve (3) to allow the hydrogen in the fuel cell stack hydrogen tail gas to pass into the low-temperature catalytic combustion device (8), and then open the air side drainage and exhaust valve (6) to allow the air side drainage and exhaust valve (6) to separate the nitrogen-oxygen mixed gas on the air side of the fuel cell stack (4), and control the separated oxygen to pass into the low-temperature catalytic combustion device (8), and control the hydrogen and the separated oxygen to be fully burned in the low-temperature catalytic combustion device.

[0030] Furthermore, the data acquisition unit further comprises:

[0031] A current sensor is provided at a power supply end of the battery stack (4) and is used to obtain an output current of the battery stack (4);

[0032] Gas pressure sensors are respectively arranged on the inner wall of the pipe at the input end of the air compressor and on the inner wall of the pipe at the inlet of the air circulation device (11), and are used to obtain the gas pressure at the input end of the air compressor and the gas pressure at the inlet of the air circulation device (11);

[0033] The temperature sensor is arranged inside the oxygen separation device (7) and is used to obtain the ambient temperature inside the oxygen separation device (7).

[0034] Furthermore, the data processing and control unit executes the following program:

[0035] After receiving the user's start-up instruction, the ventilation of the hydrogen tank (5), the oxygen tank (10) and the nitrogen tank (9) are controlled to start respectively;

[0036] Obtaining the required power of the fuel cell system, and adjusting the control valve (1) and the diverter valve (12) according to the required power to achieve a set opening that matches the required power;

[0037] Close the hydrogen side drain and exhaust valve (3) and the air side drain and exhaust valve (6), start the hydrogen circulation device (2) and the air circulation device (11), and after the gas pressure at the inlet of the air circulation device (11) reaches the set pressure, close the input end 1 of the diverter valve (12) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set value;

[0038] Monitor the output current of the fuel cell stack (4) and identify whether the current reaches the rated current matching the required power. If so, determine that the self-circulating fuel cell system is in a normal operating state and execute the next step. Otherwise, continue monitoring.

[0039] Controlling the oxygen separation device (7) to start, and opening the hydrogen side drain and exhaust valve (3), so that the hydrogen in the fuel cell hydrogen tail gas is passed into the low-temperature catalytic combustion device (8);

[0040] The air-side drain and exhaust valve (6) is opened to separate the nitrogen-oxygen mixed gas on the air side of the fuel cell stack (4) through the air-side drain and exhaust valve (6), and the separated oxygen is controlled to flow into the low-temperature catalytic combustion device (8), so that the hydrogen in the fuel cell stack hydrogen tail gas and the separated oxygen are fully burned in the low-temperature catalytic fuel device.

[0041] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0042] 1. For confined space environments where nitrogen and hydrogen cannot be discharged, an oxygen separation device is added to the tail exhaust to separate the nitrogen and oxygen mixture on the air side, and the oxygen and hydrogen are fully consumed by the low-temperature catalytic fuel device. The nitrogen is recovered to the nitrogen tank through a pressure pump, thus fully treating the nitrogen, hydrogen and oxygen in the tail gas.

[0043] 2. By setting up hydrogen circulation devices and air circulation devices, the utilization rate of the fuel cell stack input gas is effectively improved.

[0044] 3. The self-circulating fuel cell system does not require air during use and no gas is discharged, making it very suitable for high-altitude oxygen-deficient environments.

[0045] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0047] Figure 1 A schematic diagram of the composition of the self-circulating fuel cell system of Example 1 is shown;

[0048] Figure 2 A schematic diagram of the composition of the self-circulating fuel cell system of Example 2 is shown;

[0049] Figure 3A schematic diagram of the control principle of the self-circulating fuel cell system of Example 2 is shown.

[0050] Reference numerals:

[0051] 1- Control valve; 2- Hydrogen circulation device; 3- Hydrogen side drain and exhaust valve; 4- Fuel cell stack; 5- Hydrogen tank; 6- Air side drain and exhaust valve; 7- Oxygen separation device; 8- Low-temperature catalytic combustion device; 9- Nitrogen tank; 10- Oxygen tank; 11- Air circulation device; 12- Diverter valve; 13- Switch valve; 14- Pressure pump; 15- First pressure regulating valve; 16- Second pressure regulating valve. DETAILED DESCRIPTION

[0052] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0053] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0054] Example 1

[0055] One embodiment of the present invention discloses a self-circulating fuel cell system, such as Figure 1 As shown, it includes a fuel cell stack 4, a hydrogen tank 5, a control valve 1, a hydrogen circulation device 2, a hydrogen side water and exhaust valve 3, an air circulation device 11, an air side water and exhaust valve 6, an oxygen separation device 7 and a low-temperature catalytic combustion device 8.

[0056] The hydrogen inlet of the fuel cell stack 4 is connected to the outlet of the hydrogen tank 5 through a control valve 1, and to its hydrogen tail gas outlet through a hydrogen circulation device 2. The hydrogen tail gas outlet is also connected to the first input terminal of the low-temperature catalytic combustion device 8 through a hydrogen-side water and exhaust valve 3. The air inlet of the fuel cell stack 4 is connected to the oxygen-containing mixed gas through one route, and to its air tail gas outlet through an air circulation device 11. The air tail gas outlet is also connected to the second input terminal of the low-temperature catalytic combustion device 8 through an air-side water and exhaust valve 6 and the oxygen outlet of the oxygen separation device 7.

[0057] The low-temperature catalytic combustion device 8 is used to fully combust hydrogen introduced at its first input and oxygen introduced at its second input. The detailed structure of this device can be found in patents CN202023172370.3, CN201822151599.5, and CN201820745135.4. Simply replace the catalyst with a hydrogen-oxygen reaction catalyst (for example, see the East China University of Science and Technology master's thesis, "Preparation of a Low-Temperature Hydrogen Combustion Catalyst and Its Application in Purifying Hydrogen-Containing Exhaust Gas from Combustion Cells").

[0058] The structure of the oxygen separation device 7 can be found in patents CN201380039222.8, CN201920525750.9, CN202120461920.9, etc.

[0059] It should be noted that the self-circulating fuel cell system also includes a coolant control branch, which can be found in patent CN202011171825.1, etc., all of which use existing equipment.

[0060] The oxygen-containing mixed gas is a mixed gas containing oxygen, such as a mixed gas containing nitrogen and oxygen (a nitrogen-oxygen mixture), commonly air, or a mixed gas of oxygen and other inert gases (not participating in the reaction), which will be understood by those skilled in the art.

[0061] Compared with existing technologies, the fuel cell system provided in this embodiment separates the oxygen-containing mixed gas discharged from the air side of the stack by adding an oxygen separation device to the tail exhaust device. The separated oxygen and hydrogen discharged from the hydrogen side of the stack are fully burned through a low-temperature catalytic combustion device, consuming all the fuel. Nitrogen or other inert gases can be directly discharged into the environment or recovered into a designated gas storage tank. This achieves sufficient treatment of hydrogen and oxygen in the tail gas, improving the safety of the fuel cell system in a closed environment.

[0062] Example 2

[0063] Based on Example 1, an improvement has been made in which the high-permeability membrane in the oxygen separation device 7 is made of a barium-containing perovskite oxide. The barium oxide nanoparticles precipitated on the surface of the barium-containing perovskite oxide are highly active for oxygen activation and serve as active sites for oxygen exchange reactions. Therefore, they can be used to prepare high-temperature oxygen-permeable membranes, achieving efficient separation of oxygen from the air and suitable for fuel cell system applications in various scenarios.

[0064] The oxygen separation device 7 is usually a gas device with a high-temperature oxygen permeable membrane. The high-temperature oxygen permeable membrane is a membrane made of a new material, which can separate air into oxygen and nitrogen in a high-temperature environment, such as a high-permeability membrane containing barium perovskite oxide at 700°C.

[0065] The oxygen-containing mixed gas may be a nitrogen-oxygen mixed gas, including air.

[0066] Preferably, the self-circulating fuel cell system further includes a pressure pump 14 and a nitrogen tank 9. Figure 2 As shown. Moreover, the oxygen-containing mixed gas is a nitrogen-oxygen mixed gas. The nitrogen outlet of the oxygen separation device 7 is connected to the gas inlet of the nitrogen tank 9 after passing through the pressure pump 14. The nitrogen tank 9 is used to store the nitrogen introduced by the pressure pump 14.

[0067] Preferably, the self-circulating fuel cell system further includes a controller.

[0068] The controller is used to open the hydrogen side drain and exhaust valve 3 after recognizing that the self-circulating fuel cell system is in normal operation, and set the opening duty cycle of the hydrogen side drain and exhaust valve 3 to m , and control the hydrogen in the hydrogen tail gas of the fuel cell 4 to pass into the low-temperature catalytic combustion device 8; and open the air-side drainage and exhaust valve 6 to separate the nitrogen-oxygen mixed gas on the air side of the fuel cell 4 through the oxygen separation device 7, and set the opening duty ratio of the air-side drainage and exhaust valve 6 to k , and control the separated oxygen to enter the low-temperature catalytic combustion device 8, so that the hydrogen and the separated oxygen are fully burned in the low-temperature catalytic combustion device. The control principle is as follows Figure 3 shown. m, k The setting should make the flow ratio of hydrogen to oxygen less than or equal to 2:1, so as to completely consume the hydrogen in the low-temperature catalytic combustion device 8. Preferably it is 2:1, and the hydrogen and oxygen in the low-temperature catalytic combustion device 8 react completely.

[0069] The output end of the controller is connected to the control end of the control valve 1, the hydrogen circulation device 2, the hydrogen side drain and exhaust valve 3, the air circulation device 11, the air side drain and exhaust valve 6, the oxygen separation device 7, and the pressure pump 14.

[0070] Preferably, the self-circulating fuel cell system further includes an oxygen tank fuel cell system 10 and a diverter valve 12. The diverter valve 12 has an input end connected to the gas outlet of the nitrogen tank 9, an input end connected to the gas outlet of the oxygen tank fuel cell system 10, and an output end connected to the air inlet of the fuel cell stack 4. The control ends of the nitrogen tank 9, the oxygen tank fuel cell system 10, and the diverter valve 12 are all connected to the output end of the controller.

[0071] Preferably, the self-circulating fuel cell system further includes a first pressure regulating valve 15 and a second pressure regulating valve 16. The control ends of the first and second pressure regulating valves 15, 16 are both connected to the output end of the controller. The first input end of the diverter valve 12 is connected to the gas outlet of the nitrogen tank 9 via the first pressure regulating valve 15, while the second input end is connected to the gas outlet of the oxygen tank fuel cell system 10 via the second pressure regulating valve 16.

[0072] Preferably, the self-circulating fuel cell system further comprises a switch valve 13. One end of the switch valve 13 is connected to the gas inlet of the nitrogen tank 9, the other end is connected to the gas outlet of the pressure pump 14, and the control end is connected to the output end of the controller.

[0073] Preferably, the self-circulating fuel cell system further comprises an air compressor, wherein the input end of the air compressor is connected to the output end of the diverter valve 12 , the output end thereof is connected to the air inlet of the fuel cell stack 4 , and the control end thereof is connected to the output end of the controller.

[0074] The controller is further configured to obtain the gas pressure at the input end of the air compressor; and to adjust the speed of the air compressor according to the gas pressure.

[0075] Preferably, the controller further comprises a data acquisition unit and a data processing and control unit which are connected in sequence.

[0076] The data acquisition unit is used to obtain the gas pressure at the input end of the air compressor, the gas pressure at the inlet of the air circulation device 11, and the output current of the fuel cell stack 4 in real time, and send them to the data processing and control unit.

[0077] The data processing and control unit is used to start and control the ventilation of the hydrogen tank 5, the oxygen tank fuel cell system 10 and the nitrogen tank 9 respectively, and adjust the control valve 1 and the diverter valve 12 to the set opening according to the required power of the fuel cell system; and start the hydrogen circulation device 2 and the air circulation device 11. After the gas pressure at the inlet of the air circulation device 11 reaches the set pressure, the input end 1 of the diverter valve 12 is closed to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set value; and after identifying that the self-circulating fuel cell system is in normal operation according to the output current of the stack 4, first open the hydrogen side drain and exhaust valve 3 to allow the hydrogen in the hydrogen tail gas of the stack 4 to pass into the low-temperature catalytic combustion device 8, and then open the air side drain and exhaust valve 6 to allow the air side drain and exhaust valve 6 to separate the nitrogen-oxygen mixed gas on the air side of the stack 4, and control the separated oxygen to pass into the low-temperature catalytic combustion device 8, and control the hydrogen and the separated oxygen to be fully burned in the low-temperature catalytic fuel device.

[0078] Preferably, the data acquisition unit further includes a current sensor, a gas pressure sensor, and a temperature sensor.

[0079] The current sensor is provided at the power supply end of the fuel cell stack 4 and is used to obtain the output current of the fuel cell stack 4 .

[0080] The gas pressure sensors are respectively arranged on the inner wall of the pipe at the input end of the air compressor and the inner wall of the pipe at the inlet of the air circulation device 11, and are used to obtain the gas pressure at the input end of the air compressor and the gas pressure at the inlet of the air circulation device 11.

[0081] The temperature sensor is provided inside the oxygen separation device 7 and is used to obtain the ambient temperature inside the oxygen separation device 7 .

[0082] Preferably, the data processing and control unit has a display module, wherein the display screen of the display module displays the real-time output current of the battery stack 4.

[0083] Preferably, the data processing and control unit executes the following program:

[0084] S1. After receiving the user's start command, the ventilation of the hydrogen tank 5, the oxygen tank fuel cell system 10 and the nitrogen tank 9 are controlled to open;

[0085] S2 obtains the required power of the fuel cell system, and adjusts the control valve 1 and the diverter valve 12 to a set opening according to the required power;

[0086] S3. Close the hydrogen-side drain and exhaust valve 3 and the air-side drain and exhaust valve 6, start the hydrogen circulation device 2 and the air circulation device 11, and after the gas pressure at the inlet of the air circulation device 11 reaches the set pressure, close the input end 1 of the diverter valve 12 to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set value;

[0087] S4 monitors the output current of the stack 4 and identifies whether the current reaches the rated current that matches the power demand. If so, it is determined that the self-circulating fuel cell system is in normal operation and the next step is executed. Otherwise, continue monitoring.

[0088] S5. Start the oxygen separation device 7 and open the hydrogen side drain valve 3 so that the hydrogen in the hydrogen tail gas of the fuel cell 4 is passed into the low-temperature catalytic combustion device 8;

[0089] S6. Open the air-side drain and exhaust valve 6 so that the air-side drain and exhaust valve 6 separates the nitrogen-oxygen mixed gas on the air side of the fuel cell stack 4, and controls the separated oxygen to pass into the low-temperature catalytic combustion device 8, so that the hydrogen in the fuel cell stack hydrogen exhaust gas and the separated oxygen are fully burned in the low-temperature catalytic fuel device.

[0090] Preferably, the data processing and control unit further executes the following program:

[0091] S7. Identify whether the air-side drain exhaust valve 6 is open. If so, proceed to the next step. Otherwise, close the input terminal 1 of the diverter valve 12 to supplement pure oxygen to the stack 4.

[0092] S8. Control the diverter valve 12 to reach a set opening to replenish the nitrogen and oxygen mixture to the fuel cell stack 4.

[0093] Compared with Example 1, the self-circulating fuel cell system provided in this embodiment has the following beneficial effects:

[0094] 1. For confined space environments where nitrogen and hydrogen cannot be discharged, an oxygen separation device is added to the tail exhaust to separate the nitrogen and oxygen mixture on the air side, and the oxygen and hydrogen are fully consumed by the low-temperature catalytic fuel device. The nitrogen is recovered to the nitrogen tank through a pressure pump, thus fully treating the nitrogen, hydrogen and oxygen in the tail gas.

[0095] 2. By setting up hydrogen circulation devices and air circulation devices, the utilization rate of the fuel cell stack input gas is effectively improved.

[0096] 3. The self-circulating fuel cell system does not require air during use and no gas is discharged, making it very suitable for high-altitude oxygen-deficient environments.

[0097] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements over the prior art, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A self-circulating fuel cell system, characterized in that: It comprises a fuel cell stack (4), a hydrogen tank (5), a control valve (1), a hydrogen circulation device (2), a hydrogen-side water and exhaust valve (3), an air circulation device (11), an air-side water and exhaust valve (6), an oxygen separation device (7) and a low-temperature catalytic combustion device (8); wherein, The hydrogen inlet of the fuel cell stack (4) is connected to the gas outlet of the hydrogen tank (5) through the control valve (1), and is connected to its hydrogen tail gas outlet through the hydrogen circulation device (2). The hydrogen tail gas outlet is also connected to the input terminal 1 of the low-temperature catalytic combustion device (8) through the hydrogen side drainage and exhaust valve (3); The air inlet of the fuel cell stack (4) is fed with an oxygen-containing mixed gas, and is connected to its air exhaust outlet via the air circulation device (11). The air exhaust outlet is further connected to the second input terminal of the low-temperature catalytic combustion device (8) via the air-side drain and exhaust valve (6) and the oxygen outlet of the oxygen separation device (7). The low-temperature catalytic combustion device (8) is used for fully burning hydrogen introduced into the first input end thereof and oxygen introduced into the second input end thereof.

2. The self-circulating fuel cell system according to claim 1, characterized in that: The oxygen-containing mixed gas is a nitrogen-oxygen mixed gas; the system also includes a pressure pump (14) and a nitrogen tank (9); wherein, The nitrogen outlet of the oxygen separation device (7) is connected to the gas inlet of the nitrogen tank (9) after passing through a pressure pump (14); The nitrogen tank (9) is used to store nitrogen introduced through the pressure pump (14).

3. The self-circulating fuel cell system according to claim 2, characterized in that: Also includes a controller; wherein, The controller is used to open the hydrogen side water discharge and exhaust valve (3) after recognizing that the self-circulating fuel cell system is in a normal operating state, and set the opening duty ratio of the hydrogen side water discharge and exhaust valve (3) to m , and control the hydrogen in the hydrogen tail gas of the fuel cell stack to flow into the low-temperature catalytic combustion device (8); and open the air-side drainage and exhaust valve (6) to separate the nitrogen-oxygen mixed gas on the air side of the fuel cell stack (4) through the oxygen separation device (7), and set the opening duty ratio of the air-side drainage and exhaust valve (6) to k , and controlling the separated oxygen to flow into the low-temperature catalytic combustion device (8), so that the hydrogen and the separated oxygen are fully burned in the low-temperature catalytic combustion device.

4. The self-circulating fuel cell system according to claim 3, characterized in that: It also includes an oxygen tank (10) and a diverter valve (12); wherein, The first input end of the diverter valve (12) is connected to the gas outlet of the nitrogen tank (9), the second input end is connected to the gas outlet of the oxygen tank (10), and the output end is connected to the air inlet of the fuel cell stack (4); The control ends of the nitrogen tank (9), oxygen tank (10), and diverter valve (12) are all connected to the output end of the controller.

5. The self-circulating fuel cell system according to claim 4, characterized in that: It also includes a first pressure regulating valve (15) and a second pressure regulating valve (16); wherein, The first input end of the diverter valve (12) is connected to the gas outlet of the nitrogen tank (9) via the first pressure regulating valve (15), and the second input end is connected to the gas outlet of the oxygen tank (10) via the second pressure regulating valve (16); The control ends of the first pressure regulating valve (15) and the second pressure regulating valve (16) are both connected to the output end of the controller.

6. The self-circulating fuel cell system according to any one of claims 3 to 5, characterized in that: Also includes a switch valve (13); wherein, One end of the switch valve (13) is connected to the gas inlet of the nitrogen tank (9), the other end is connected to the gas outlet of the pressure pump (14), and the control end is connected to the output end of the controller.

7. The self-circulating fuel cell system according to claim 4 or 5, characterized in that: Also includes an air compressor; wherein, The input end of the air compressor is connected to the output end of the diverter valve (12), the output end is connected to the air inlet of the fuel cell stack (4), and the control end is connected to the output end of the controller; The controller is further configured to obtain the gas pressure at the input end of the air compressor; and to adjust the speed of the air compressor according to the gas pressure.

8. The self-circulating fuel cell system according to claim 7, characterized in that: The controller further comprises: A data acquisition unit is used to respectively acquire the gas pressure at the input end of the air compressor, the gas pressure at the inlet of the air circulation device (11), and the output current of the fuel cell (4) in real time, and send them to the data processing and control unit; The data processing and control unit is used to start and control the ventilation opening of the hydrogen tank (5), the oxygen tank (10) and the nitrogen tank (9), and adjust the control valve (1) and the diverter valve (12) to reach the set opening according to the required power of the fuel cell system; and start the hydrogen circulation device (2) and the air circulation device (11). After the gas pressure at the inlet of the air circulation device (11) reaches the set pressure, close the input end of the diverter valve (12) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set value; and after identifying that the self-circulating fuel cell system is in a normal operating state according to the output current of the fuel cell stack (4), first open the hydrogen side drainage and exhaust valve (3) to allow the hydrogen in the fuel cell stack hydrogen tail gas to pass into the low-temperature catalytic combustion device (8), and then open the air side drainage and exhaust valve (6) to allow the air side drainage and exhaust valve (6) to separate the nitrogen-oxygen mixed gas on the air side of the fuel cell stack (4), and control the separated oxygen to pass into the low-temperature catalytic combustion device (8), and control the hydrogen and the separated oxygen to be fully burned in the low-temperature catalytic combustion device.

9. The self-circulating fuel cell system according to claim 8, characterized in that: The data acquisition unit further comprises: A current sensor is provided at a power supply end of the battery stack (4) and is used to obtain an output current of the battery stack (4); Gas pressure sensors are respectively arranged on the inner wall of the pipe at the input end of the air compressor and on the inner wall of the pipe at the inlet of the air circulation device (11), and are used to obtain the gas pressure at the input end of the air compressor and the gas pressure at the inlet of the air circulation device (11); The temperature sensor is arranged inside the oxygen separation device (7) and is used to obtain the ambient temperature inside the oxygen separation device (7).

10. The self-circulating fuel cell system according to claim 8 or 9, characterized in that: The data processing and control unit executes the following procedures: After receiving the user's start-up instruction, the ventilation of the hydrogen tank (5), the oxygen tank (10) and the nitrogen tank (9) are controlled to start respectively; Obtaining the required power of the fuel cell system, and adjusting the control valve (1) and the diverter valve (12) according to the required power to achieve a set opening that matches the required power; Close the hydrogen side drain and exhaust valve (3) and the air side drain and exhaust valve (6), start the hydrogen circulation device (2) and the air circulation device (11), and after the gas pressure at the inlet of the air circulation device (11) reaches the set pressure, close the input end 1 of the diverter valve (12) to ensure that the oxygen partial pressure of the gas entering the stack always exceeds the set value; Monitor the output current of the fuel cell stack (4) and identify whether the current reaches the rated current matching the required power. If so, determine that the self-circulating fuel cell system is in a normal operating state and execute the next step. Otherwise, continue monitoring. Controlling the oxygen separation device (7) to start, and opening the hydrogen side drain and exhaust valve (3), so that the hydrogen in the fuel cell hydrogen tail gas is passed into the low-temperature catalytic combustion device (8); The air-side drain and exhaust valve (6) is opened to separate the nitrogen-oxygen mixed gas on the air side of the fuel cell stack (4) through the air-side drain and exhaust valve (6), and the separated oxygen is controlled to flow into the low-temperature catalytic combustion device (8), so that the hydrogen in the fuel cell stack hydrogen tail gas and the separated oxygen are fully burned in the low-temperature catalytic fuel device.

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