A fuel cell system suitable for operation in a low oxygen environment

Abstract

The application provides a fuel cell system suitable for low-oxygen environment operation, and belongs to the technical field of fuel cells, and solves the problem of low energy conversion efficiency when the existing system is applied to low-oxygen environment operation. The system comprises a stack, a hydrogen tank, a hydrogen spraying device, an ejector, an oxygen separator, an air compressor, a distribution valve and a controller. The hydrogen gas inlet of the stack is connected to the gas outlet of the hydrogen tank in sequence through the ejector and the hydrogen spraying device, the hydrogen tail gas outlet of the stack is connected to the flow guide inlet of the ejector, and the air inlet of the stack is connected to the output end of the distribution valve. The oxygen outlet of the oxygen separator is connected to the input end one of the distribution valve through the air compressor, and the nitrogen outlet of the oxygen separator is connected to the input end two of the distribution valve. The controller is used for collecting the pressure difference of the oxygen outlet of the oxygen separator at regular time intervals to identify whether the high-temperature oxygen permeable membrane in the oxygen separator needs to be activated, if yes, after the fuel cell is shut down, the oxygen separator is executed for activation heating until it is identified that the active substance in the high-temperature oxygen permeable membrane is reduced, and then the fuel cell is started.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cell technology, and particularly relates to a fuel cell system suitable for low-oxygen environment operation. BACKGROUND

[0002] A fuel cell system is a device that continuously converts chemical energy in continuously supplied fuel and oxidant into electrical energy. It usually includes an electric pile and peripheral hydrogen, air, cooling equipment and other components. The electric pile further includes a proton exchange membrane, a catalyst layer, a gas diffusion layer, a bipolar plate, etc. Since the theoretical voltage of a single cell is 1.23 V, it usually achieves high-power output by connecting several hundred single cells in parallel.

[0003] At present, fuel cell systems are mainly used in hydrogen fuel cell vehicles. Hydrogen fuel cell vehicles are a new energy vehicle with broad development and application prospects, and have many advantages such as short hydrogen refueling time and long driving range.

[0004] However, when the fuel cell system is applied to some low-oxygen environment scenarios, such as high altitude or airtight environment, since the oxygen partial pressure is a key parameter for the internal reaction of the fuel cell, and the nitrogen gas in the air does not participate in the reaction, which will result in very low energy conversion efficiency of the fuel cell. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a fuel cell system suitable for low-oxygen environment operation, to solve the problem of low energy conversion efficiency when the existing system is applied to low-oxygen environment operation.

[0006] In one aspect, the embodiments of the present application provide a fuel cell system suitable for low-oxygen environment operation, comprising an electric pile, a hydrogen tank, a hydrogen spraying device, an ejector, an oxygen separator, an air compressor, a distribution valve and a controller.

[0007] The hydrogen gas inlet of the electric pile is connected to the gas outlet of the hydrogen tank through the ejector and the hydrogen spraying device in sequence, the hydrogen tail gas outlet of the electric pile is connected to the flow inlet of the ejector, and the air inlet of the electric pile is connected to the output end of the distribution valve; the oxygen outlet of the oxygen separation device is connected to the input end one of the distribution valve through the air compressor, and the nitrogen outlet is connected to the input end two of the distribution valve.

[0008] The controller is used to collect the pressure difference of the oxygen outlet of the oxygen separator at regular intervals when the fuel cell system is in normal operation state, to identify whether the high-temperature oxygen-permeable membrane in the oxygen separator needs to be activated, if so, to control the fuel cell system to shut down, and then to perform activation heating on the oxygen separator until it is identified that the active substance in the high-temperature oxygen-permeable membrane is reduced, and then to perform start-up of the fuel cell system.

[0009] The beneficial effects of the above technical solutions are as follows: a durable fuel cell system suitable for working in a low-oxygen environment is proposed. By arranging the oxygen separator, the oxygen content of the air end of the stack can be effectively improved, thereby improving the energy conversion efficiency of the fuel cell. After the high-temperature oxygen permeable membrane is used for a period of time, the chemical active substances in the membrane will slowly react with carbon dioxide in the air, resulting in a decrease in oxygen permeation rate and an increase in pressure difference. A large number of tests have shown that the oxygen permeation rate is positively correlated with the gas pressure difference between the input end and the oxygen outlet of the oxygen separator. Therefore, in the above scheme, the controller identifies whether the oxygen permeation rate is reduced to the lower limit (i.e., whether the high-temperature oxygen permeable membrane needs to be activated) according to the gas pressure difference between the input end and the oxygen outlet of the oxygen separator at regular intervals. Once activation is needed, the entire fuel cell system is shut down, and the on-board battery or other battery is used for power supply, and the oxygen separator is controlled separately to perform activation heating. After the active substances are reduced, the fuel cell system is started again to supply power, thereby effectively improving the durability of the fuel cell system.

[0010] Based on the further improvement of the above system, the fuel cell system further comprises a hydrogen side pressure regulating valve and an air side pressure regulating valve; wherein,

[0011] The input end of the hydrogen side pressure regulating valve is connected to the hydrogen tail gas outlet of the stack, and the control end is connected to the output end of the controller;

[0012] The input end of the air side pressure regulating valve is connected to the air tail gas outlet of the stack, and the control end is connected to the output end of the controller.

[0013] Further, the controller further comprises:

[0014] The data acquisition unit is used to acquire the gas pressures at the input end and the oxygen outlet of the oxygen separator in real time, respectively, and send them to the data processing and control unit;

[0015] The data processing and control unit is used to identify whether the high-temperature oxygen permeable membrane in the oxygen separator needs to be activated when the fuel cell system is in a normal running state, to obtain the gas pressure difference between the input end and the oxygen outlet of the oxygen separator at regular intervals according to the gas pressures at the input end and the oxygen outlet of the oxygen separator, and to control the fuel cell system to shut down if the high-temperature oxygen permeable membrane needs to be activated. After that, the oxygen separator is activated and heated to a set temperature until it is identified that the active substances in the high-temperature oxygen permeable membrane are reduced, and then the fuel cell system is started, otherwise, the running state of the fuel cell system at the current time is maintained unchanged. T

[0016] Further, the data acquisition unit further comprises:

[0017] ​Gas pressure sensors are respectively arranged on the inner wall of the pipeline at the input end of the oxygen separator, the pipeline at the oxygen outlet, the input pipeline of the hydrogen side pressure regulating valve and the air side pressure regulating valve, and the pipeline at the hydrogen inlet and air inlet of the electric pile, for obtaining the gas pressure at the arranged position;

[0018] A temperature sensor is arranged in the oxygen separator, for obtaining the environment temperature in the oxygen separator;

[0019] A current sensor is arranged at the power supply end of the electric pile, for obtaining the real-time output current of the electric pile.

[0020] Further, the data processing and control unit executes the following procedures:

[0021] The real-time output current of the electric pile is obtained at a fixed time, to identify whether the fuel cell system is in a normal running state; if it is in the normal running state, the next step is executed, otherwise, the running state of the fuel cell system at the current time is continued;

[0022] The gas pressure at the input end of the oxygen separator is obtained P 1, the gas pressure at the oxygen outlet is obtained P 2, the gas pressure difference between the input end and the oxygen outlet of the oxygen separator is obtained P 2- P 1;

[0023] According to the absolute value of the pressure difference P 2- P 1 and the threshold value P 0, it is identified whether the high-temperature oxygen-permeable membrane in the oxygen separator needs to be activated; if the absolute value of the pressure difference P 2- P 1 exceeds the threshold value P 0, it is determined that activation is needed, the activation flag bit is set to 1, and the next step is executed; otherwise, it is determined that activation is not needed, the activation flag bit is set to 0, and the shutdown of the fuel cell system is executed;

[0024] After the fuel cell system is shut down, the oxygen separator is activated and heated to a set temperature T , until the heating time reaches a set value t , it is determined that the active substance in the high-temperature oxygen-permeable membrane has been reduced, the oxygen separator is closed, and then the startup of the fuel cell system is executed according to the user's startup instruction.

[0025] Further, the data acquisition unit further comprises:

[0026] An air flow meter is arranged at the inlet of the oxygen separator, for obtaining the instantaneous flow of air at the current time.

[0027] Further, the controller further executes the following procedures to realize the startup function of the fuel cell system:

[0028] After receiving the starting instruction of the user, the power required by the stack is obtained, and the target hydrogen flow rate into the stack and the target air flow rate into the stack matched with the power required by the stack are determined;

[0029] The opening degree of the distribution valve is adjusted to a set opening degree matched with the atmospheric pressure;

[0030] The air compressor is controlled to start and work at a set rotating speed, and the pressure difference of the oxygen separator at the input end-oxygen outlet gas is obtained;

[0031] According to the pressure difference, the rotating speed of the air compressor is adjusted, so that the air flow rate at the air inlet of the stack reaches the target air flow rate into the stack;

[0032] The gas outlet of the hydrogen tank is controlled to be opened, and the hydrogen injection device is started, so that the hydrogen flow rate at the hydrogen inlet of the stack reaches the target hydrogen flow rate into the stack, and the starting of the fuel cell system is completed.

[0033] Further, the fuel cell system further comprises a sealing valve and an air circulating device; wherein,

[0034] One end of the sealing valve is suspended, and the other end is connected with the nitrogen outlet of the oxygen separator, and the control end is connected with the output end of the controller;

[0035] The input end of the air circulating device is connected with the air tail gas outlet of the stack, the output end is connected with the air inlet of the stack, and the control end is connected with the output end of the controller.

[0036] Further, the controller further executes the following program:

[0037] The air circulating device is started;

[0038] The gas pressure at the input end of the air circulating device is monitored, and after the pressure reaches a set value, the input end two of the distribution valve is closed, and the sealing valve is opened, so that the nitrogen is continuously and continuously sent out, and the pure oxygen is supplemented to the stack, so that the oxygen partial pressure of the gas into the stack always exceeds a set value.

[0039] Further, the fuel cell system further comprises a gas-water separator, a pressure pump and a recovery switch valve; wherein,

[0040] The hydrogen tail gas outlet of the stack is further connected with the gas inlet of the hydrogen tank in sequence through the above-mentioned gas-water separator, pressure pump and recovery switch valve;

[0041] The control ends of the pressure pump and the recovery switch valve are respectively connected with the output end of the controller.

[0042] Compared with the prior art, the present application can at least realize one of the following beneficial effects:

[0043] 1. The gas-water separator, pressure pump and recovery switch valve are added in the tail exhaust, which can recycle the unused hydrogen in time and prevent the waste of fuel gas.

[0044] 2. The utilization rate of the input gas of the electric pile is effectively improved by setting the ejector and air circulation device.

[0045] 3. In the pure oxygen environment, the oxidation is too strong, in order to improve the service life of the parts, therefore a certain component of nitrogen gas is doped, but the nitrogen gas obtained from the oxygen separator is discharged after the air tail gas at the inlet of the air circulation device reaches the set pressure, so as to ensure the volume ratio of oxygen in the air entering the pile and improve the energy conversion efficiency of the fuel cell.

[0046] The summary section is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary section is not intended to identify key or essential features of the disclosure, and is not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0047] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference characters designate like elements in the various figures.

[0048] Figure 1 A schematic diagram of a fuel cell system suitable for low-oxygen environment operation is shown in Figure 1.

[0049] Figure 2 A schematic diagram of a fuel cell system suitable for low-oxygen environment operation is shown in Figure 1.

[0050] Figure 3 A schematic diagram of the air system of the fuel cell system of Example 2 is shown in Figure 2.

[0051] Figure 4 A schematic diagram of the activation control principle of the fuel cell system of Example 2 is shown in Figure 3.

[0052] LIST OF REFERENCE NUMERALS

[0053] 1 - air flow meter; 2 - air compressor; 3 - oxygen separator; 4 - sealing valve; 5 - electric pile; 6 - air side pressure regulating valve; 7 - distribution valve; P1 - gas pressure sensor (provided on the inner wall of the pipeline at the input end of the oxygen separator); P2 - gas pressure sensor (provided on the inner wall of the pipeline at the oxygen outlet of the oxygen separator). DETAILED DESCRIPTION

[0054] Embodiments of the present disclosure will be described below in greater detail with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0055] The term "comprising" and variations thereof as used herein are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0056] Embodiment 1

[0057] One embodiment of the present disclosure discloses a fuel cell system suitable for low-oxygen environment operation, such as Figure 1 As shown, it comprises a stack, a hydrogen tank, a hydrogen injection device, an ejector, an oxygen separator, an air compressor, a distribution valve and a controller.

[0058] The hydrogen inlet of the stack is connected to the gas outlet of the hydrogen tank through the ejector and the hydrogen injection device in sequence, the hydrogen tail gas outlet of the stack is connected to the flow guide inlet of the ejector, and the air inlet of the stack is connected to the output end of the distribution valve; the oxygen outlet of the oxygen separation device is connected to the input end one of the distribution valve through the air compressor, and the nitrogen outlet is connected to the input end two of the distribution valve.

[0059] The controller is configured to, when the fuel cell system is in normal operation, periodically collect the input-end-oxygen-outlet gas pressure difference of the oxygen separator to identify whether the high-temperature oxygen-permeable membrane in the oxygen separator needs to be activated, and if so, to control the fuel cell system to shut down, then perform activation heating on the oxygen separator until it is identified that the active substance in the high-temperature oxygen-permeable membrane is reduced, and then perform start-up of the fuel cell system.

[0060] Specifically, the input-end-oxygen-outlet gas pressure difference of the oxygen separator is P 2- P 1, wherein P 1 is the gas pressure at the input end of the oxygen separator, P 2 is the gas pressure at the oxygen outlet of the oxygen separator.

[0061] When the input-oxygen outlet gas pressure difference of the oxygen separator is greater than a set threshold value (which can be calibrated by the laboratory), it is determined that the high-temperature oxygen-permeable membrane in the oxygen separator needs to be activated, otherwise, it is determined that it does not need to be activated. Alternatively, the input-oxygen outlet gas pressure difference of the oxygen separator in a set period of time is input into a trained deep neural network or other learning network, and the recognition result of whether the high-temperature oxygen-permeable membrane in the oxygen separator needs to be activated can also be obtained.

[0062] The recognition result of the active substance being reduced can be achieved by heating for a set value (which can be calibrated by the laboratory), or by referring to the method described in CN201780019523.2 and other existing recognition methods.

[0063] The specific temperature for performing activation heating on the oxygen separator depends on the reduction temperature of the active substance in the high-temperature oxygen-permeable membrane. Different active substances of different materials have different reduction temperatures.

[0064] It should be noted that the structure of the oxygen separator can be referred to in patents CN201380039222.8, CN201920525750.9, CN202120461920.9, etc.

[0065] The engine also includes a coolant control branch, which can be referred to in patent CN202011171825.1, etc. All use existing equipment and do not need to be described in detail. This part is omitted here and can be understood by those skilled in the art.

[0066] Compared with the prior art, the embodiment proposes a durable fuel cell system suitable for working in a low-oxygen environment. By setting an oxygen separator, the oxygen content at the air end of the stack can be effectively improved, thereby improving the energy conversion efficiency of the fuel cell. Since the chemical active substance in the membrane of the high-temperature oxygen-permeable membrane in the oxygen separator will slowly react with carbon dioxide in the air after being used for a period of time, the oxygen permeation rate will decrease and the pressure difference will increase. A large number of tests have shown that the oxygen permeation rate is positively correlated with the input-oxygen outlet gas pressure difference of the oxygen separator. Therefore, in the above scheme, the controller identifies whether the oxygen permeation rate has decreased to the lower limit (i.e., whether the high-temperature oxygen-permeable membrane needs to be activated) according to the input-oxygen outlet gas pressure difference of the oxygen separator in a timely manner. Once it needs to be activated, the entire fuel cell system is shut down, and the vehicle-mounted battery or other battery is used for power supply, and the oxygen separator is controlled to perform activation heating, and after the active substance is reduced, the fuel cell system is started again for power supply, thereby effectively improving the durability of the fuel cell system.

[0067] Embodiment 2

[0068] On the basis of the improvement of embodiment 1, the high permeable membrane in the oxygen separation device uses barium-containing perovskite oxide material. The barium oxide nanoparticles precipitated on the surface of the barium-containing perovskite oxide have super-high activity for oxygen activation, and the nanoparticles are also active sites for oxygen exchange reaction, so they can be used to prepare high-temperature oxygen permeable membrane to realize efficient separation of oxygen in air, suitable for fuel cell system application in various scenes. After the high-temperature oxygen permeable membrane of the oxygen separator is used for a period of time, the chemical active substances in the membrane will slowly react with carbon dioxide in the air, resulting in a decrease in oxygen permeation rate and an increase in pressure difference. Raising the temperature to above 800℃ can effectively reduce the activity of the active substances.

[0069] Preferably, the fuel cell system further comprises a hydrogen side pressure regulating valve and an air side pressure regulating valve, as Figures 2-3 described. The input end of the hydrogen side pressure regulating valve is connected to the hydrogen tail gas outlet of the stack, and the control end is connected to the output end of the controller. The input end of the air side pressure regulating valve is connected to the air tail gas outlet of the stack, and the control end is connected to the output end of the controller.

[0070] Preferably, the controller further comprises a data acquisition unit and a data processing and control unit.

[0071] The data acquisition unit is used to acquire the gas pressures at the input end and the oxygen outlet of the oxygen separator in real time, respectively, and send them to the data processing and control unit.

[0072] The data processing and control unit is used to identify when the fuel cell system is in normal operation, and to obtain the input end-oxygen outlet gas pressure difference of the oxygen separator according to the gas pressures at the input end and the oxygen outlet of the oxygen separator at regular intervals, to identify whether the high-temperature oxygen permeable membrane in the oxygen separator needs to be activated, and if so, to control the fuel cell system to shut down, and then to perform activation heating on the oxygen separator at a set temperature T (exemplarily, set to 800℃) until it is identified that the active substances in the high-temperature oxygen permeable membrane are reduced, and then to perform start-up of the fuel cell system, otherwise, to maintain the current operating state of the fuel cell system unchanged.

[0073] Preferably, the data acquisition unit further comprises a gas pressure sensor, a temperature sensor, a current sensor, an air flow meter, and an atmospheric pressure sensor.

[0074] The gas pressure sensor is arranged on the inner wall of the pipeline at the input end and the oxygen outlet of the oxygen separator, the input end of the hydrogen side pressure regulating valve and the air side pressure regulating valve, and the hydrogen inlet and air inlet of the stack, respectively, to acquire the gas pressure at the arranged position.

[0075] The temperature sensor is arranged in the interior of the oxygen separator to acquire the ambient temperature in the oxygen separator.

[0076] A current sensor, located at the power supply end of the fuel cell stack, is used to acquire the real-time output current of the fuel cell stack.

[0077] An air flow meter, located at the inlet of the oxygen separator, is used to obtain the instantaneous air flow rate at the current moment.

[0078] An atmospheric pressure sensor, located outside the fuel cell stack, is used to obtain the atmospheric pressure at the current moment.

[0079] Preferably, the data processing and control unit executes the following program:

[0080] S1. Periodically acquire the real-time output current of the fuel cell stack to identify whether the fuel cell system is in normal operating condition; if it is in normal operating condition, proceed to the next step; otherwise, continue with the current operating status of the fuel cell system.

[0081] S2. Obtain the gas pressure at the input end of the oxygen separator. P 1. Gas pressure at the oxygen outlet P 2. Obtain the pressure difference between the input end and the oxygen outlet of the oxygen separator. P 2- P 1;

[0082] S3. Based on this pressure difference P 2- P The absolute value of 1 and the threshold P 0. Compare and identify whether the high-temperature oxygen-permeable membrane inside the oxygen separator needs activation. If the pressure difference... P 2- P The absolute value of 1 exceeds the threshold. P If the value is 0, activation is required; set the activation flag to 1 and proceed to the next step. Otherwise, activation is not required; set the activation flag to 0 and shut down the fuel cell system.

[0083] S4. After the fuel cell system is shut down, set the oxygen separator to the set temperature. T Activation heating continues until the heating time reaches the set value. t Once it is determined that the active material in the high-temperature oxygen-permeable membrane has been reduced, the oxygen separator is shut down, and then the fuel cell system is started up according to the user's start-up command.

[0084] Control principle such as Figure 4 As shown.

[0085] Preferably, the controller further executes the following program to realize the start-up function of the fuel cell system:

[0086] S5. After receiving the user's start command, obtain the stack power requirement and determine the target flow rates of hydrogen and air entering the stack that match the stack power requirement.

[0087] S6. Adjust the opening of the distribution valve to a set opening matching the atmospheric pressure (which can be calibrated according to the atmospheric pressure);

[0088] S7. Control the air compressor to start and work at a set rotating speed, and obtain the pressure difference between the input end of the oxygen separator and the oxygen outlet gas;

[0089] S8. Adjust the rotating speed of the air compressor according to the pressure difference, so that the air flow at the air inlet of the stack reaches the target air flow into the stack;

[0090] S9. Control the gas outlet of the hydrogen tank to open, start the hydrogen injection device, so that the hydrogen flow at the hydrogen inlet of the stack reaches the target hydrogen flow into the stack, and complete the start of the fuel cell system.

[0091] Preferably, the data processing and control unit has a display module. The display screen of the display module displays the instantaneous flow of air at the current time, the real-time output current of the stack, and the hydrogen inlet pressure and the air inlet pressure.

[0092] Preferably, the fuel cell system further comprises a sealing valve, an air circulating device, as shown in Figures 2-3

[0093] One end of the sealing valve is suspended, and the other end is connected to the nitrogen outlet of the oxygen separator, and the control end is connected to the output end of the controller.

[0094] The input end of the air circulating device is connected to the air tail gas outlet of the stack, the output end is connected to the air inlet of the stack, and the control end is connected to the output end of the controller.

[0095] Preferably, the controller further executes the following program:

[0096] S10. Start the air circulating device;

[0097] S11. Monitor the gas pressure at the input end of the air circulating device, and after the pressure reaches a set value, close the input end of the distribution valve, and open the sealing valve to continuously send out nitrogen and supplement pure oxygen to the stack to ensure that the oxygen partial pressure of the gas into the stack always exceeds a set value.

[0098] Preferably, the fuel cell system further comprises a gas-water separator, a pressure pump, and a recovery switch valve, wherein the hydrogen tail gas outlet of the stack is further connected to the gas inlet of the hydrogen tank in sequence through the above-mentioned gas-water separator, pressure pump, and recovery switch valve; the control ends of the pressure pump and the recovery switch valve are respectively connected to the output end of the controller.

[0099] ​Preferably, the hydrogen tail gas outlet of the stack is further connected with the gas inlet of the hydrogen tank in sequence through a hydrogen side pressure regulating valve, a gas-water separator, a pressure pump and a recovery switch valve; and the control ends of the pressure pump and the recovery switch valve are connected with the output ends of the controller respectively.

[0100] Compared with the prior art, the fuel cell system provided by the embodiment has the following beneficial effects:

[0101] 1. The gas-water separator, the pressure pump and the recovery switch valve are added in the tail gas, so that the unused hydrogen can be recovered in time to prevent fuel gas waste.

[0102] 2. The utilization rate of the input gas of the stack is effectively improved by setting the ejector and the air circulation device.

[0103] 3. In the pure oxygen environment, the oxidation is too strong, so a certain amount of nitrogen is doped to improve the service life of the parts. However, when the air tail gas reaches the set pressure at the inlet of the air circulation device, the nitrogen obtained by the oxygen separator will be discharged, so as to ensure the volume ratio of oxygen in the stack and improve the energy conversion efficiency of the fuel cell.

[0104] The above has described the embodiments of the present disclosure, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application or improvement of the prior art of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell system suitable for operation in a low oxygen environment, characterized by, This includes fuel cell stacks, hydrogen tanks, hydrogen injection equipment, ejectors, oxygen separators, air compressors, distribution valves, and controllers; The hydrogen inlet of the fuel cell stack is connected to the gas outlet of the hydrogen tank via an ejector and a hydrogen injection device. The hydrogen tail gas outlet of the fuel cell stack is connected to the inlet of the ejector. The air inlet of the fuel cell stack is connected to the output end of the distribution valve. The oxygen outlet of the oxygen separation unit is connected to the input end one of the distribution valve via an air compressor. The nitrogen outlet of the oxygen separation unit is connected to the input end two of the distribution valve. The controller is used to periodically collect the gas pressure difference between the input end and the oxygen outlet of the oxygen separator when the fuel cell system is in normal operation to identify whether the high-temperature oxygen permeable membrane in the oxygen separator needs to be activated. If so, after the fuel cell system is shut down, the controller performs activation heating on the oxygen separator until the active material in the high-temperature oxygen permeable membrane is reduced, and then starts the fuel cell system. It also includes hydrogen-side pressure regulating valves and air-side pressure regulating valves; among which, The input end of the hydrogen-side pressure regulating valve is connected to the hydrogen tail gas outlet of the fuel cell stack, and the control end is connected to the output end of the controller. The input end of the air-side pressure regulating valve is connected to the air exhaust outlet of the fuel cell stack, and the control end is connected to the output end of the controller. The controller further includes: The data acquisition unit is used to acquire the gas pressure at the input end and the oxygen outlet of the oxygen separator in real time and send it to the data processing and control unit. The data processing and control unit is used to identify when the fuel cell system is in normal operation. It periodically calculates the gas pressure difference between the input and outlet of the oxygen separator based on the gas pressure at the input and outlet of the oxygen separator. It then identifies whether the high-temperature oxygen permeable membrane in the oxygen separator needs to be activated. If so, it controls the fuel cell system to shut down and performs activation heating on the oxygen separator at a set temperature T until the active material in the high-temperature oxygen permeable membrane is reduced. Then, it starts the fuel cell system. Otherwise, it maintains the current operating state of the fuel cell system. The data acquisition unit further includes: Gas pressure sensors are installed on the inner walls of the pipes at the input end of the oxygen separator, the oxygen outlet, the input end pipes of the hydrogen-side pressure regulating valve and the air-side pressure regulating valve, and the inner walls of the hydrogen inlet and air inlet pipes of the fuel cell stack, respectively, to obtain the gas pressure at the installation location. A temperature sensor, located inside the oxygen separator, is used to obtain the ambient temperature inside the oxygen separator; A current sensor is located at the power supply end of the fuel cell stack to obtain the real-time output current of the fuel cell stack. The data processing and control unit executes the following program: The system periodically acquires the real-time output current of the fuel cell stack to identify whether the fuel cell system is in normal operating condition. If it is in normal operating condition, proceed to the next step; otherwise, continue with the current operating status of the fuel cell system. The gas pressure P1 at the input end of the oxygen separator and the gas pressure P2 at the oxygen outlet are obtained respectively, and the gas pressure difference P2-P1 between the input end and the oxygen outlet of the oxygen separator is obtained. The absolute value of the pressure difference P2-P1 is compared with the threshold P0 to identify whether the high-temperature oxygen permeable membrane in the oxygen separator needs to be activated. If the absolute value of the pressure difference P2-P1 exceeds the threshold P0, it is determined that activation is required, the activation flag is set to 1, and the next step is executed; otherwise, it is determined that activation is not required, the activation flag is set to 0, and the fuel cell system is shut down. After the fuel cell system is shut down, the oxygen separator is activated and heated to a set temperature T until the heating time reaches the set value t, indicating that the active material in the high-temperature oxygen permeable membrane has been reduced. After the oxygen separator is shut down, the fuel cell system is started up according to the user's start-up command.

2. The fuel cell system suitable for operation in low-oxygen environments according to claim 1, characterized in that, The data acquisition unit also includes: An air flow meter is installed at the inlet of the oxygen separator to obtain the instantaneous air flow rate at the current moment.

3. The fuel cell system suitable for operation in low-oxygen environments according to claim 2, characterized in that, The controller also executes the following program to enable the fuel cell system to start up: After receiving the user's start command, the stack power requirement is obtained, and the target flow rates of hydrogen and air entering the stack that match the stack power requirement are determined. Adjust the opening of the distribution valve to the set opening that matches the atmospheric pressure; Control the air compressor to start and operate at the set speed, and obtain the gas pressure difference between the input end and the oxygen outlet of the oxygen separator; Adjust the speed of the air compressor according to the pressure difference so that the air flow at the air inlet of the fuel cell stack reaches the target air flow rate into the stack. Open the gas outlet of the hydrogen tank and start the hydrogen injection equipment to ensure that the hydrogen flow rate at the hydrogen inlet of the fuel cell stack reaches the target flow rate of hydrogen entering the stack, thus completing the startup of the fuel cell system.

4. The fuel cell system suitable for operation in low-oxygen environments according to any one of claims 1-3, characterized in that, It also includes sealing valves and air circulation devices; among which, One end of the sealing valve is suspended, and the other end is connected to the nitrogen outlet of the oxygen separator. The control end of the sealing valve is connected to the output end of the controller. The input end of the air circulation device is connected to the air exhaust outlet of the fuel cell stack, the output end of the air circulation device is connected to the air inlet of the fuel cell stack, and the control end of the air circulation device is connected to the output end of the controller.

5. The fuel cell system suitable for operation in low-oxygen environments according to claim 4, characterized in that, The controller also executes the following program: Start the air circulation system; Monitor the gas pressure at the input end of the air circulation device. Once the pressure reaches the set value, close the second input end of the distribution valve and open the sealing valve to continuously deliver nitrogen and replenish pure oxygen to the fuel cell stack, ensuring that the oxygen partial pressure of the gas entering the stack always exceeds the set value.

6. The fuel cell system suitable for operation in low-oxygen environments according to any one of claims 1, 2, 3, and 5, characterized in that, It also includes a gas-liquid separator, a pressure pump, and a recovery switch valve; among which, The hydrogen tail gas outlet of the fuel cell stack is also connected to the gas inlet of the hydrogen tank via the aforementioned gas-liquid separator, pressure pump, and recovery switch valve in sequence. The control terminals of the pressure pump and the recovery switch valve are respectively connected to the output terminal of the controller.

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