Fuel cell system shutdown and startup protection device and method

Abstract

The invention relates to the technical field of fuel cells, in particular to a fuel cell system shutdown and startup protection device and method.The fuel cell system shutdown and startup protection device comprises a tail exhaust pipeline and a purging pipeline, the tail exhaust pipeline is connected to a tail exhaust pipe of a fuel cell stack, and a back pressure valve is arranged on the tail exhaust pipeline; external air is prevented from entering a tail discharge pipe of the fuel cell stack, and a hydrogen-air interface is prevented from being formed when the fuel cell system is started again; the purging pipeline is connected to an anode runner of the fuel cell stack, a gas storage tank is connected to the purging pipeline, and the purging pipeline is used for performing nitrogen purging and filling on the anode runner of the fuel cell stack when the fuel cell system is shut down, so that the pressure of the anode runner is higher than that of a cathode runner, and oxygen of a cathode is prevented from diffusing to the anode to form a hydrogen-air interface. Through the tail exhaust pipeline and the purging pipeline, a hydrogen-air interface is prevented from being generated when the fuel cell system is stopped and started, carbon corrosion generated by the hydrogen-air interface is reduced, and the performance of the hydrogen fuel cell is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system shutdown and startup protection device and method. Background Art

[0002] A hydrogen fuel cell is a power generation device that directly converts the chemical energy of hydrogen and oxygen into electrical energy. Its basic principle is the reverse reaction of water electrolysis. Hydrogen and oxygen are supplied to the anode and cathode through the hydrogen path and air path respectively. After hydrogen diffuses outward through the anode and reacts with the electrolyte, it releases electrons and reaches the cathode through an external load.

[0003] When the hydrogen fuel cell system is shut down, hydrogen and oxygen will remain in the anode and cathode of the hydrogen fuel cell. Due to the concentration gradient between the anode and cathode, the oxygen in the cathode will slowly diffuse to the anode, forming a hydrogen-air interface. Moreover, after the hydrogen fuel cell system is shut down, the outside air will diffuse into the anode flow channel of the stack through the tail pipe and membrane electrode of the stack. When the hydrogen fuel cell system is started again, at the moment when hydrogen enters the anode, a hydrogen-air interface will also be formed in the anode flow field. The existence of the hydrogen-air interface will cause a high potential to form at the cathode, resulting in oxidation of the catalyst carbon carrier material and carbon corrosion, which will lead to the attenuation of the performance of the hydrogen fuel cell. Summary of the invention

[0004] The present invention provides a fuel cell system shutdown protection device and method, which are used to solve the defect in the prior art that when a hydrogen fuel cell system is shut down, a hydrogen-air interface is generated, which leads to the degradation of hydrogen fuel cell performance. The device and method can avoid the generation of a hydrogen-air interface when the fuel cell system is shut down, thereby protecting the fuel cell stack and extending the system life.

[0005] The present invention provides a fuel cell system shutdown and startup protection device, comprising a tail exhaust pipeline and a purge pipeline, wherein the tail exhaust pipeline is connected to the tail exhaust pipe of a fuel cell stack and is used to discharge the tail gas generated by the fuel cell, and a back pressure valve is arranged on the tail exhaust pipeline to isolate external air from entering the tail exhaust pipe of the fuel cell stack; the purge pipeline is connected to the anode flow channel of the fuel cell stack, and a gas storage tank is connected to the purge pipeline, and is used to purge and fill the anode flow channel of the fuel cell stack with gas when the fuel cell system is shut down.

[0006] According to a fuel cell system shutdown and startup protection device provided by the present invention, the tail exhaust pipeline is also connected in parallel with a recovery pipeline, a nitrogen separator is provided on the recovery pipeline, the nitrogen outlet of the nitrogen separator is connected to the gas storage tank, and the gas storage tank is a nitrogen storage tank.

[0007] According to a fuel cell system shutdown and startup protection device provided by the present invention, the tail exhaust pipeline includes a front section pipeline, a middle section pipeline and a rear section pipeline, the back pressure valve is arranged on the front section pipeline, one end of the front section pipeline is connected to the tail exhaust pipe of the fuel cell stack, and the other end is connected to the middle section pipeline through a first three-way valve, the middle section pipeline is connected to the rear section pipeline through a second three-way valve, and a muffler is arranged on the rear section pipeline.

[0008] The two ends of the recovery pipeline are respectively connected to the first three-way valve and the second three-way valve, so that the recovery pipeline and the middle pipeline form a parallel circuit.

[0009] According to a fuel cell system shutdown and startup protection device provided by the present invention, a gas-water separator is also provided on the recovery pipeline, the liquid outlet of the gas-water separator is used to discharge water, the gas outlet of the gas-water separator is connected to the nitrogen separator through a pipeline; the nitrogen outlet of the nitrogen separator is connected to the gas storage tank through a one-way valve.

[0010] According to a fuel cell system shutdown protection device provided by the present invention, the gas storage tank is provided with a pressure sensor and a pressure relief valve, the pressure sensor is used to monitor the pressure in the gas storage tank, and the pressure relief valve is used to relieve the pressure of the gas storage tank.

[0011] According to a fuel cell system shutdown and startup protection device provided by the present invention, a blower and an overflow valve are arranged on the purge pipeline, the purge pipeline is connected to a third three-way valve, a first port of the third three-way valve is connected to a hydrogen path, a second port of the third three-way valve is connected to the purge pipeline, and a third port of the third three-way valve is connected to an anode flow channel of a fuel cell stack.

[0012] The present invention also provides a fuel cell system shutdown and startup protection method, which is applicable to any one of the fuel cell system shutdown and startup protection devices described above, and the fuel cell system shutdown and startup protection method comprises: when the fuel cell system is operating normally, the exhaust gas generated by the fuel cell stack is controlled to be discharged from the tail exhaust pipe through the tail exhaust pipeline; when the fuel cell system is shut down, the exhaust gas generated by the fuel cell stack is controlled to separate nitrogen from the recovery pipeline and store it in a gas storage tank, and the fuel cell system is discharged, hydrogen consumes oxygen, and nitrogen fills the anode flow channel in sequence, so that the anode flow channel pressure of the fuel cell stack is greater than the cathode flow channel pressure, and then shuts down.

[0013] According to a fuel cell system shutdown and startup protection method provided by the present invention, the process of discharging the fuel cell system includes: discharging the fuel cell system based on an external circuit, and keeping the anode flow channel pressure of the fuel cell stack always higher than the cathode flow channel pressure, controlling the exhaust gas generated by the fuel cell stack to separate nitrogen from the recovery pipeline and store it in a gas storage tank, and completing the discharge process when the fuel cell system current is less than the set current value.

[0014] According to a fuel cell system shutdown and startup protection method provided by the present invention, the process of hydrogen and oxygen consumption of the fuel cell system includes: controlling the air path to stop gas supply, maintaining gas supply in the hydrogen path, using the hydrogen in the anode flow channel of the fuel cell stack to consume the oxygen in the cathode flow channel of the fuel cell stack, and maintaining the anode flow channel pressure of the fuel cell stack not lower than a first set value a.

[0015] The average voltage of a single cell of the fuel cell stack and the pressure of the cathode flow channel of the fuel cell stack are monitored. When the average voltage of a single cell of the fuel cell stack is lower than a set threshold or the pressure of the cathode flow channel of the fuel cell stack is lower than a second set value b, the hydrogen circuit stops supplying gas to complete the hydrogen oxygen consumption process; the first set value a and the second set value b satisfy b<a-20.

[0016] According to a fuel cell system shutdown and startup protection method provided by the present invention, the process of filling the anode flow channel of the fuel cell system with nitrogen includes: filling the anode flow channel of the fuel cell stack with nitrogen through a gas storage tank, monitoring the anode flow channel pressure of the fuel cell stack, and when the anode flow channel pressure of the fuel cell stack is greater than the set pressure value, stopping the nitrogen filling, completing the nitrogen filling process of the anode flow channel, and controlling the fuel cell system to shut down.

[0017] The fuel cell system shutdown protection device and method provided by the present invention can prevent external air from entering the anode flow channel of the fuel cell stack through the tail exhaust pipe after the fuel cell system is shut down, and cause the fuel cell system to form a hydrogen-air interface when it is restarted by connecting the tail exhaust pipe of the fuel cell stack to the tail exhaust pipe, and setting a back pressure valve on the tail exhaust pipe; the anode flow channel of the fuel cell stack is connected to the purge pipeline, and nitrogen can be output through the gas storage tank on the purge pipeline, and the anode flow channel is purged with nitrogen when the fuel cell system is shut down, and the anode flow channel can be filled with nitrogen to ensure that the pressure of the anode flow channel is greater than the pressure of the cathode flow channel, and prevent the oxygen of the cathode from diffusing to the anode to form a hydrogen-air interface. The present invention avoids the generation of a hydrogen-air interface when the fuel cell system is shut down and starts by using the tail exhaust pipeline and the purge pipeline, reduces carbon corrosion caused by the hydrogen-air interface, and ensures the performance of the hydrogen fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the working principle of the fuel cell system shutdown and startup protection device provided by the present invention.

[0020] Figure numerals: 1, tail exhaust pipeline; 101, front section pipeline; 102, middle section pipeline; 103, rear section pipeline; 2, back pressure valve; 3, purge pipeline; 4, gas storage tank; 5, recovery pipeline; 6, nitrogen separator; 7, first three-way valve; 8, second three-way valve; 9, muffler; 10, gas-water separator; 11, one-way valve; 12, pressure sensor; 13, pressure relief valve; 14, blower; 15, overflow valve; 16, third three-way valve. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0024] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0026] Combine the following Figure 1 The specific embodiments describe the fuel cell system shutdown protection device and method of the present invention.

[0027] One embodiment of the present invention provides a fuel cell system shutdown protection device, see Figure 1 As shown, the fuel cell system shutdown and startup protection device includes a tail exhaust pipeline 1 and a purge pipeline 3. The tail exhaust pipeline 1 is connected to the tail exhaust pipe of the fuel cell stack and is used to discharge the exhaust gas generated by the fuel cell. A back pressure valve 2 is provided on the tail exhaust pipeline 1 to isolate external air from entering the tail exhaust pipe of the fuel cell stack; the purge pipeline 3 is connected to the anode flow channel of the fuel cell stack, and a gas storage tank 4 is connected to the purge pipeline 3 for purging and filling the anode flow channel of the fuel cell stack with gas when the fuel cell system is shut down.

[0028] It can be understood that the fuel cell system shutdown protection device of this embodiment is connected to the stack of the fuel cell system, and the tail exhaust pipe of the fuel cell stack is connected to the tail exhaust pipeline 1. Through the back pressure valve 2 set on the tail exhaust pipeline 1, it can prevent external air from entering the anode flow channel of the stack through the tail exhaust pipe after the fuel cell system is shut down, causing the fuel cell system to start up again to form a hydrogen-air interface; the anode flow channel of the fuel cell stack is connected to the purge pipeline 3, and the gas storage tank 4 on the purge pipeline 3 can output a stable and inert gas, such as nitrogen. When the fuel cell system is shut down, the anode flow channel is purged with nitrogen, and the anode flow channel can be filled with nitrogen to ensure that the pressure of the anode flow channel is greater than the pressure of the cathode flow channel, and prevent the oxygen in the cathode from diffusing to the anode to form a hydrogen-air interface. The fuel cell system shutdown protection device of this embodiment avoids the generation of a hydrogen-air interface when the fuel cell system is shut down through the tail exhaust pipeline 1 and the purge pipeline 3, reduces the carbon corrosion caused by the hydrogen-air interface, and ensures the performance of the hydrogen fuel cell.

[0029] In some embodiments of the fuel cell system shutdown and startup protection device of the present invention, the tail exhaust pipeline 1 is also connected in parallel with a recovery pipeline 5, and a nitrogen separator 6 is provided on the recovery pipeline 5. The nitrogen outlet of the nitrogen separator 6 is connected to the gas storage tank 4, and the gas storage tank 4 is a nitrogen storage tank.

[0030] It can be understood that in this embodiment, the flow direction of the tail gas can be realized by setting a controller to control the opening and closing of the pipeline valve. When the fuel cell operates normally (with DCDC input current), the tail gas of the air path is controlled to enter the tail exhaust pipeline 1 from the tail exhaust pipe and be discharged into the atmosphere. At this time, the system is still operating normally; when the fuel cell enters the normal shutdown instruction, the tail gas of the air path is controlled to enter the recovery pipeline 5. The tail gas can be separated into nitrogen through the nitrogen separator 6 and stored in the gas storage tank 4, so as to prepare for the subsequent filling of nitrogen into the anode flow channel through the purge pipeline 3 to realize the recovery and utilization of the tail gas.

[0031] Specifically, in some examples, the tail pipe 1 includes a front pipe 101, a middle pipe 102 and a rear pipe 103, the back pressure valve 2 is arranged on the front pipe 101, one end of the front pipe 101 is connected to the tail pipe of the fuel cell stack, and the other end is connected to the middle pipe 102 through the first three-way valve 7, the middle pipe 102 is connected to the rear pipe 103 through the second three-way valve 8, and the rear pipe 103 is provided with a muffler 9. The two ends of the recovery pipe 5 are respectively connected to the first three-way valve 7 and the second three-way valve 8, so that the recovery pipe 5 and the middle pipe 102 form a parallel circuit.

[0032] See also Figure 1As shown, when the fuel cell is operating normally (with DCDC input current), the tail exhaust gas of the air path passes through the front section pipeline 101, the first three-way valve 7, the middle section pipeline 102, and the second three-way valve 8 in sequence, reaches the rear section pipeline 103, and is then processed by the muffler 9 and discharged into the atmosphere. At this time, the system is still operating normally. When the fuel cell enters the normal shutdown instruction, the tail exhaust gas of the air path passes through the front section pipeline 101 and the first three-way valve 7, and enters the recovery pipeline 5. In the recovery pipeline 5, the tail exhaust gas is separated from nitrogen in the nitrogen separator 6, and the separated nitrogen enters the gas storage tank 4 for storage. The other separated gases pass through the second three-way valve 8 to reach the rear section pipeline 103, and are then processed by the muffler 9 and discharged into the atmosphere.

[0033] Furthermore, a gas-water separator 10 is provided on the recovery pipeline 5, and the liquid outlet of the gas-water separator 10 is used to discharge water, and the gas outlet of the gas-water separator 10 is connected to the nitrogen separator 6 through a pipeline; the nitrogen outlet of the nitrogen separator 6 is connected to the gas storage tank 4 through a one-way valve 11.

[0034] The tail gas entering the recovery pipeline 5 must first pass through the gas-water separator 10, and the gas-water separator 10 performs gas-water separation. The separated water is discharged from the liquid outlet of the gas-water separator 10, and the separated dry gas enters the nitrogen separator 6 through the gas outlet and pipeline of the gas-water separator 10 for nitrogen separation. The nitrogen separated by the nitrogen separator 6 enters the gas storage tank 4 through the one-way valve 11. Because the pressure in the gas storage tank 4 is relatively high, the one-way valve 11 can prevent nitrogen from flowing back.

[0035] In some embodiments of the fuel cell system shutdown protection device of the present invention, the gas storage tank 4 is provided with a pressure sensor 12 and a pressure relief valve 13, the pressure sensor 12 is used to monitor the pressure in the gas storage tank 4, and the pressure relief valve 13 is used to relieve the pressure of the gas storage tank 4.

[0036] The nitrogen separated from the gas storage tank 4 passes through the one-way valve 11 and enters the gas storage tank 4 for storage. When the pressure sensor 12 of the gas storage tank 4 detects that the pressure in the tank is higher than the safety set pressure (assuming 150 kPa, absolute pressure), the pressure relief valve 13 is triggered to open, and part of the nitrogen is discharged to reduce the pressure of the gas storage tank 4. When the pressure sensor 12 detects that the pressure in the tank is lower than the safety set pressure, the pressure relief valve 13 is closed. In this embodiment, the pressure of the gas storage tank 4 is always within the safety pressure range through the cooperation of the pressure sensor 12 and the pressure relief valve 13.

[0037] In some embodiments of the fuel cell system shutdown and startup protection device of the present invention, a blower 14 and an overflow valve 15 are provided on the purge line 3, the purge line 3 is connected to the third three-way valve 16, the first port of the third three-way valve 16 is connected to the hydrogen path, the second port of the third three-way valve 16 is connected to the purge line 3, and the third port of the third three-way valve 16 is connected to the anode flow channel of the fuel cell stack.

[0038] When the fuel cell operates normally, hydrogen is provided to the anode flow channel of the fuel cell stack through the hydrogen path to participate in the chemical reaction of the fuel cell stack. At this time, the purge line 3 is disconnected from the anode flow channel of the fuel cell stack by the selective opening of the port of the third three-way valve 16, and the fuel cell operates normally. When the fuel cell receives a normal shutdown command and shuts down, if the anode flow channel needs nitrogen, the port of the third three-way valve 16 connected to the hydrogen path is closed to stop the hydrogen supply, and the port of the third three-way valve 16 connected to the purge line 3 is opened to connect the purge line 3 to the anode flow channel of the fuel cell stack. The controller controls the blower 14 to start working, and the nitrogen in the gas storage tank 4 is delivered to the anode flow channel of the fuel cell stack. At the same time, the nitrogen supply flow rate can be controlled by the overflow valve 15. Nitrogen enters the anode flow channel of the fuel cell stack, so that the anode flow channel of the fuel cell stack is filled with nitrogen. The pressure in the anode flow channel is higher than the pressure in the cathode flow channel. At this time, no matter whether the fuel cell system is shut down for a short time or a long time, the pressure in the anode flow channel is always higher than the pressure in the cathode flow channel, and the residual oxygen in the cathode will not diffuse to the anode. When the system is started again, the formation of hydrogen-air interface is avoided, thereby protecting the stack and extending the system life.

[0039] On the other hand, the present invention also provides a fuel cell system shutdown and startup protection method, which is applicable to the fuel cell system shutdown and startup protection device in any one of the above-mentioned embodiments. The fuel cell system shutdown and startup protection method includes: when the fuel cell system is operating normally, the exhaust gas generated by the fuel cell stack is controlled to be discharged from the tail exhaust pipe through the tail exhaust pipeline 1; when the fuel cell system is shut down, the exhaust gas generated by the fuel cell stack is controlled to separate nitrogen from the recovery pipeline 5 and store it in the gas storage tank 4, and the fuel cell system is discharged, hydrogen consumes oxygen, and nitrogen fills the anode flow channel in sequence, so that the anode flow channel pressure of the fuel cell stack is greater than the cathode flow channel pressure, and then shuts down.

[0040] Specifically, see Figure 1 As shown, when the fuel cell is operating normally (with DCDC input current), the tail exhaust gas of the air path passes through the front section pipeline 101, the first three-way valve 7, the middle section pipeline 102, the second three-way valve 8 in sequence, reaches the rear section pipeline 103, and then is processed by the muffler 9 and discharged into the atmosphere. At this time, the system is still operating normally. When the fuel cell enters the normal shutdown instruction, the system will go through the steps of discharge, hydrogen oxygen consumption and nitrogen filling the anode flow channel.

[0041] When the fuel cell system is performing the discharge step, the fuel cell system is discharged based on the external circuit. At this time, the system current is small, and the system anode flow channel pressure is always higher than the cathode flow channel pressure. The exhaust gas (N2, O2 and other impurity gases) discharged from the air path passes through the front pipeline 101 and the first three-way valve 7 and enters the recovery pipeline 5. In the recovery pipeline 5, the exhaust gas must first pass through the gas-water separator 10, and the gas-water separator 10 performs gas-water separation. The separated water is discharged from the liquid outlet of the gas-water separator 10. The separated dry gas enters the nitrogen separator 6 through the gas outlet and pipeline of the gas-water separator 10 for nitrogen separation. The nitrogen separated by the nitrogen separator 6 enters the gas storage tank 4 through the one-way valve 11 for storage. The other gases separated by the nitrogen separator 6 reach the rear pipeline 103 through the second three-way valve 8, and are then discharged into the atmosphere after being processed by the muffler 9. The gas storage tank 4 has a built-in pressure sensor 12 and a pressure relief valve 13. When the pressure sensor 12 monitors the pressure in the storage tank > 150 kPa, the pressure relief valve 13 opens. When the pressure sensor 12 monitors the pressure ≤ 150 kPa, the pressure relief valve 13 stops. In this process, when the current of the fuel cell system is less than the set current value, the discharge process is completed and the next hydrogen oxygen consumption step is performed.

[0042] When the fuel cell system performs the hydrogen and oxygen consumption step, first, the air circuit is controlled to stop supplying gas and the hydrogen circuit is maintained to supply gas. When the air compressor of the air circuit stops rotating, the system voltage drops rapidly and the hydrogen and oxygen consumption step is officially entered. The hydrogen in the anode flow channel of the fuel cell stack consumes the oxygen in the cathode flow channel of the fuel cell stack and the anode flow channel pressure of the fuel cell stack is maintained not lower than the first set value a. The stack voltage and the air side pressure (cathode flow channel pressure) drop rapidly. At this time, the average voltage of the fuel cell stack cell and the pressure of the cathode flow channel of the fuel cell stack are monitored. When the average voltage of the fuel cell stack cell is lower than the set threshold or the pressure of the cathode flow channel of the fuel cell stack is lower than the second set value b (b<a-20), the hydrogen circuit stops supplying gas and the hydrogen and oxygen consumption process is completed. At this time, the hydrogen and air side pressure and the average voltage of the stack cell continue to decrease, and the next step of nitrogen filling the anode flow channel is started.

[0043] When the fuel cell system is performing the step of filling the anode flow channel with nitrogen, the blower 14 is turned on to allow the nitrogen stored in the gas tank 4 to re-enter the hydrogen flow channel through the blower 14 via the overflow valve 15 and the third three-way valve 16, monitor the anode flow channel pressure of the fuel cell stack, and monitor the pressure in the gas tank 4 monitored by the pressure sensor 12. When the pressure in the gas tank 4 is less than 105 kPa, the nitrogen in the gas tank 4 basically all enters the anode flow channel, and the anode flow channel pressure of the fuel cell stack is greater than the set pressure value (the set pressure value can be set according to the specifications of the actual fuel cell, and the set pressure value satisfies that the anode flow channel pressure can always be greater than the cathode flow channel pressure after shutdown). At this time, the nitrogen filling can be stopped to complete the step of filling the anode flow channel with nitrogen. Since the anode flow channel pressure can always be greater than the cathode flow channel pressure, the residual air in the cathode flow channel cannot penetrate into the anode flow channel. When the system is started again, the formation of the hydrogen-air interface in the anode flow channel can be avoided, which is beneficial to improving the life of the stack.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell system shutdown protection device, characterized in that: include: A tail exhaust pipeline (1), the tail exhaust pipeline (1) being connected to the tail exhaust pipe of the fuel cell stack and used for exhausting the tail gas generated by the fuel cell, and the tail exhaust pipeline (1) being provided with a back pressure valve (2) to prevent external air from entering the tail exhaust pipe of the fuel cell stack; A purge pipeline (3), the purge pipeline (3) being connected to an anode flow channel of a fuel cell stack, the purge pipeline (3) being connected to a gas storage tank (4) for purging and filling the anode flow channel of the fuel cell stack with gas when the fuel cell system is shut down.

2. The fuel cell system shutdown protection device according to claim 1, characterized in that: The tail exhaust pipeline (1) is also connected in parallel to a recovery pipeline (5), and a nitrogen separator (6) is provided on the recovery pipeline (5). The nitrogen outlet of the nitrogen separator (6) is connected to the gas storage tank (4), and the gas storage tank (4) is a nitrogen storage tank.

3. The fuel cell system shutdown protection device according to claim 2, characterized in that: The tail exhaust pipeline (1) comprises a front section pipeline (101), a middle section pipeline (102) and a rear section pipeline (103); the back pressure valve (2) is arranged on the front section pipeline (101); one end of the front section pipeline (101) is connected to the tail exhaust pipe of the fuel cell stack, and the other end is connected to the middle section pipeline (102) via a first three-way valve (7); the middle section pipeline (102) is connected to the rear section pipeline (103) via a second three-way valve (8); and a muffler (9) is arranged on the rear section pipeline (103); The two ends of the recovery pipeline (5) are respectively connected to the first three-way valve (7) and the second three-way valve (8), so that the recovery pipeline (5) and the middle pipeline (102) form a parallel circuit.

4. The fuel cell system shutdown protection device according to claim 3, characterized in that: The recovery pipeline (5) is also provided with a gas-water separator (10); the liquid outlet of the gas-water separator (10) is used to discharge water; the gas outlet of the gas-water separator (10) is connected to the nitrogen separator (6) via a pipeline; and the nitrogen outlet of the nitrogen separator (6) is connected to the gas storage tank (4) via a one-way valve (11).

5. The fuel cell system shutdown protection device according to claim 4, characterized in that: The gas storage tank (4) is provided with a pressure sensor (12) and a pressure relief valve (13); the pressure sensor (12) is used to monitor the pressure in the gas storage tank (4); and the pressure relief valve (13) is used to relieve the pressure in the gas storage tank (4).

6. The fuel cell system shutdown protection device according to any one of claims 1 to 5, characterized in that: The purge pipeline (3) is provided with a blower (14) and a relief valve (15); the purge pipeline (3) is connected to a third three-way valve (16); a first port of the third three-way valve (16) is connected to a hydrogen path; a second port of the third three-way valve (16) is connected to the purge pipeline (3); and a third port of the third three-way valve (16) is connected to an anode flow channel of a fuel cell stack.

7. A fuel cell system shutdown protection method, characterized in that: The fuel cell system shutdown and startup protection device is applicable to any one of claims 2 to 6, and the fuel cell system shutdown and startup protection method comprises: When the fuel cell system operates normally, the exhaust gas generated by the fuel cell stack is controlled to be discharged from the tail exhaust pipe through the tail exhaust pipeline (1); When the fuel cell system is shut down, the tail gas generated by the fuel cell stack is controlled to separate nitrogen from the recovery pipeline (5) and store it in the gas storage tank (4), and the fuel cell system is discharged, hydrogen consumes oxygen, and nitrogen fills the anode flow channel in sequence, so that the anode flow channel pressure of the fuel cell stack is greater than the cathode flow channel pressure, and then shuts down.

8. The fuel cell system shutdown protection method according to claim 7, characterized in that: The process of discharging the fuel cell system includes: discharging the fuel cell system based on an external circuit, and maintaining the anode flow channel pressure of the fuel cell stack always higher than the cathode flow channel pressure, controlling the exhaust gas generated by the fuel cell stack to separate nitrogen from the recovery pipeline (5) and store it in the gas storage tank (4), and completing the discharge process when the fuel cell system current is less than the set current value.

9. The fuel cell system shutdown protection method according to claim 7, characterized in that: The process of performing hydrogen and oxygen consumption on the fuel cell system includes: controlling the air path to stop gas supply, maintaining gas supply in the hydrogen path, using the hydrogen in the anode flow channel of the fuel cell stack to consume the oxygen in the cathode flow channel of the fuel cell stack, and maintaining the anode flow channel pressure of the fuel cell stack not lower than a first set value a; The average voltage of a single cell of the fuel cell stack and the pressure of the cathode flow channel of the fuel cell stack are monitored. When the average voltage of a single cell of the fuel cell stack is lower than a set threshold or the pressure of the cathode flow channel of the fuel cell stack is lower than a second set value b, the hydrogen circuit stops supplying gas to complete the hydrogen oxygen consumption process; the first set value a and the second set value b satisfy b<a-20.

10. The fuel cell system shutdown protection method according to claim 7, characterized in that: The process of filling the anode flow channel of the fuel cell system with nitrogen comprises: filling the anode flow channel of the fuel cell stack with nitrogen through a gas storage tank (4), monitoring the anode flow channel pressure of the fuel cell stack, and stopping the nitrogen filling when the anode flow channel pressure of the fuel cell stack is greater than a set pressure value, completing the nitrogen filling process of the anode flow channel, and controlling the fuel cell system to shut down.

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