Fuel cell engine shutdown purge system and control method and fuel cell system

Abstract

The application provides a fuel cell engine shutdown purging system, a control method thereof and a fuel cell system. The purging system comprises a regulating valve, a hydrogen nozzle, a water distribution device, a tail valve, a three-way valve, a hydrogen circulation device, an outlet air throttle and an inlet air throttle, the inlet one of the regulating valve is connected with a hydrogen source, the inlet two is connected with a nitrogen source, the outlet is connected with the inlet one of the hydrogen nozzle, the outlet of the hydrogen nozzle is connected with the anode inlet of an electric pile, the anode outlet of the electric pile is connected with the inlet of the water distribution device, the outlet one of the water distribution device is connected with the inlet of the hydrogen circulation device, the outlet two is connected with the tail valve, the outlet of the hydrogen circulation device is connected with the inlet of the three-way valve, the outlet one of the three-way valve is connected with the inlet two of the hydrogen nozzle, the outlet two is connected with the inlet of the inlet air throttle, the outlet of the inlet air throttle is connected with the cathode inlet of the electric pile, and the inlet of the outlet air throttle is connected with the cathode outlet of the electric pile. The cathode and the anode adopt the same N2 gas source for purging, so that the hydrogen-oxygen interface is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell, in particular to a fuel cell engine shutdown purging system, a control method thereof and a fuel cell system. BACKGROUND

[0002] The proton exchange membrane fuel cell engine system is a power generation device for converting chemical energy of reducing agent H2 into electric energy. Since no combustion is involved, the Carnot cycle limitation is avoided, and the energy utilization rate can reach 40% to 60%. At the same time, carbon and nitrogen compounds generated by combustion are avoided, which is very friendly to the environment. It is an important way to replace fossil energy.

[0003] During the operation of the proton exchange membrane fuel cell engine system in winter (zero below), a large amount of water is generated in the cathode of the engine system. Due to the osmotic effect of water, the water generated in the cathode moves to the anode. The fuel cell engine system will freeze when it operates in winter (zero below). Since the position of the purging system is mostly in the environment, the water in the purging system is in three states: water, a mixture of water and ice, and ice. The existence of the latter two substances may cause blockage in the flow channel, the membrane electrode, and the hydrogen / air pipeline, or in the parts, which hinders the entry of the reaction gas and causes the performance of the fuel cell to decay and the start-up to fail.

[0004] The existing purging strategy is to purify the anode with hydrogen and the cathode with air. This part of hydrogen is wasted, thereby reducing the utilization rate of hydrogen. At the same time, due to the difference in gas partial pressure between the anode and the cathode and the sealing reason, oxygen will appear in the anode. When starting, hydrogen and oxygen will meet in the anode due to the injection of hydrogen into the anode, and a floating hydrogen-oxygen interface is formed at this time. High potential caused by frequent start-stop causes carbon corrosion, and carbon corrosion during shutdown is more serious than that during start-up, which reduces the service life of the fuel cell. As described in Patent No. CN112838249, a purging system for a fuel cell, the air purging path has a branch, which cannot avoid the formation of a hydrogen-oxygen interface in the anode during start-stop, causing irreversible damage to the catalyst layer and the membrane electrode. As described in Patent No. CN109616688A, a low-voltage power supply mode is provided for the engine during shutdown of the fuel cell, which alleviates the problem of poor power supply stability of the purging system.

[0005] The prior art purges the water generated on the cathode air side for many aspects, and how the water on the air side is discharged, thereby ignoring the problem of water permeating from the cathode to the anode. Due to the presence of the water, the anode side flow channel, the membrane electrode, and the hydrogen / air pipeline, or the parts such as the hydrogen injector and the hydrogen circulating pump, can be disabled due to the freezing of the permeated water, which can affect the second start of the engine; if the anode is purged by air, the anode will inevitably form a hydrogen-oxygen interface, at which time the anode potential will be greatly reduced, and the cathode potential will be instantaneously increased, resulting in carbon corrosion and damage to the stack; if the anode is purged by hydrogen, the utilization rate of hydrogen will be reduced, and the formation of the hydrogen-oxygen interface cannot be avoided.

[0006] Therefore, it is urgent to provide a fuel cell engine shutdown purging system, a control method thereof, and a fuel cell system to solve the above technical problems in the prior art. SUMMARY

[0007] The present application aims to provide a fuel cell engine shutdown purging system, a control method thereof, and a fuel cell system, which can avoid the occurrence of hydrogen / air cross leakage caused by excessive pressure on the cathode and anode sides, reduce accidental factors, increase the utilization rate of hydrogen, and reduce costs.

[0008] To achieve the above-mentioned purpose, the following technical solutions are provided:

[0009] The present application provides a fuel cell engine shutdown purging system, which comprises a regulating valve, a hydrogen injector, a water distribution device, a tail discharge valve, a three-way valve, a hydrogen circulating device, an air outlet throttle, and an air inlet throttle, wherein the inlet one of the regulating valve is connected with a hydrogen source, the inlet two is connected with a nitrogen source, the outlet is connected with the inlet one of the hydrogen injector, the outlet of the hydrogen injector is connected with the anode inlet of a stack, the anode outlet of the stack is connected with the inlet of the water distribution device, the outlet one of the water distribution device is connected with the inlet of the hydrogen circulating device, the outlet two is connected with the tail discharge valve, the outlet of the hydrogen circulating device is connected with the inlet of the three-way valve, the outlet one of the three-way valve is connected with the inlet two of the hydrogen injector, the outlet two is connected with the inlet of the air inlet throttle, the outlet of the air inlet throttle is connected with the cathode inlet of the stack, and the inlet of the air outlet throttle is connected with the cathode outlet of the stack.

[0010] Optionally, the discharge outlet of the tail discharge valve is connected with a mixing discharge point, and / or the outlet of the air outlet throttle is connected with a mixing discharge point.

[0011] Optionally, the fuel cell engine shutdown purging system further comprises a controller, which is in communication connection with the regulating valve and the three-way valve, and is used for controlling the opening degrees of the control valve and the three-way valve.

[0012] Optionally, the controller is an upper computer.

[0013] Optionally, the hydrogen injection is provided with a high pressure sensor and a low pressure sensor.

[0014] Optionally, the tail exhaust valve is provided with a heating element.

[0015] The application also provides a control method of the fuel cell engine shutdown purging system according to any one of the above technical solutions, comprising the following steps:

[0016] S100: switching the control valve from hydrogen to nitrogen;

[0017] S200: controlling the inlet pressure to 140kPa-160kPa for anode purging and cathode purging;

[0018] S300: opening the outlet two of the three-way valve.

[0019] Optionally, the anode purging and the cathode purging in S200 are both pulse air purging.

[0020] Optionally, the inlet pressure in S200 is controlled to 150kPa absolute pressure.

[0021] The application also provides a fuel cell system comprising a stack and the fuel cell engine shutdown purging system according to any one of the above technical solutions.

[0022] Compared with the prior art, the fuel cell engine shutdown purging system, the control method thereof and the fuel cell system provided by the application can realize anode and cathode purging by adding a regulating valve and the action of a three-way valve, automatically controlling the switching of gas and the flow direction of gas according to a set program.

[0023] 1. The application can reduce the liquid water in the circulating pump after shutdown, and shorten the cold start time.

[0024] 2. The application forms a separate circulating gas branch, and uses nitrogen for purging without the need of making large changes to the system architecture.

[0025] 3. The application prevents the formation of an anode side hydrogen-oxygen interface, which can cause corrosion of the C carrier and reduce the engine performance.

[0026] 4. The application increases the hydrogen utilization rate and reduces the cost.

[0027] 5. The application uses the same gas source and the same pressure, and eliminates the occurrence of hydrogen-oxygen mutual mixing.

[0028] 6. The application reduces the human error factors caused by manual switching of gas.

[0029] 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 refer to like elements throughout. BRIEF DESCRIPTION OF DRAWINGS

[0030] 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 refer to like elements throughout.

[0031] Figure 1 A structure diagram of a fuel cell engine stop purge system according to an embodiment of the present application is shown.

[0032] Reference Signs:

[0033] 1 - stack; 2 - regulating valve; 3 - hydrogen jet; 4 - water separator; 5 - exhaust valve; 6 - three-way valve; 7 - hydrogen circulation device; 8 - intake air throttle; 9 - exhaust air throttle; 10 - controller. DETAILED DESCRIPTION

[0034] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which like reference characters refer to like elements throughout. The embodiments of the present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0035] As used herein, the term "includes" and its variants are meant to be

[0036] As Figure 1As shown, the fuel cell engine shutdown purging system provided by the embodiment comprises a regulating valve 2, a hydrogen nozzle 3, a water separation device 4, a tail valve 5, a three-way valve 6, a hydrogen circulation device 7, an air outlet throttle 9 and an air inlet throttle 8, the inlet one of the regulating valve 2 is connected with a hydrogen source, the inlet two is connected with a nitrogen source, the outlet is connected with the inlet one of the hydrogen nozzle 3, the outlet of the hydrogen nozzle 3 is connected with the anode inlet of the stack 1, the anode outlet of the stack 1 is connected with the inlet of the water separation device 4, the outlet one of the water separation device 4 is connected with the inlet of the hydrogen circulation device 7, the outlet two is connected with the tail valve 5, the outlet of the hydrogen circulation device 7 is connected with the inlet of the three-way valve 6, the outlet one of the three-way valve 6 is connected with the inlet two of the hydrogen nozzle 3, the outlet two is connected with the inlet of the air inlet throttle 8, the outlet of the air inlet throttle 8 is connected with the cathode inlet of the stack 1, the inlet of the air outlet throttle 9 is connected with the cathode outlet of the stack 1.

[0037] Preferably, the outlet of the tail valve 5 is connected with a mixing point, and the outlet of the air outlet throttle 9 is connected with the mixing point, which avoids environmental pollution and facilitates cleaning and saves manpower.

[0038] Optionally, the fuel cell engine shutdown purging system further comprises a controller 10, which is in communication connection with the regulating valve 2 and the three-way valve 6, and is used for controlling the opening degree of the control valve and the three-way valve 6, and the controller 10 can automatically control the switching of the gas and the flow direction of the gas according to the set program after being programmed, thereby reducing the uncertain factors caused by manual switching.

[0039] Preferably, the controller 10 of the embodiment is an upper computer, which is convenient for users to observe and operate.

[0040] Optionally, high-pressure sensors and low-pressure sensors are arranged in the hydrogen nozzle 3, which are used for detecting the pressure of the gas to control the pressure of the gas entering the stack. Further, a heating device is arranged in the tail valve 5, which can heat the gas to achieve a suitable discharge temperature. Preferably, the hydrogen circulation device 7 of the embodiment is a circulating pump, and an ejector can also be selected in other embodiments.

[0041] The application further provides a control method of the fuel cell engine shutdown purging system according to any one of the above technical solutions, which comprises the following steps:

[0042] S100: setting a control program of the controller 10, and specifically, the program must pass through the process of “standby→self-check→start→run→load reduction” of the engine;

[0043] S200: switching the control valve from hydrogen to nitrogen, and specifically, the regulating valve 2 can be opened by an external VCU controller 10. Since the same gas source is used, the risk of membrane electrode leakage caused by different pressures on the anode side and the cathode side is avoided, and since the inert gas N2 is used, a hydrogen-oxygen interface that can damage the catalyst cannot be formed on the anode side;

[0044] S200: Control the pressure into the stack to be 140kPa-160kPa (absolute pressure) to carry out anode purging and cathode purging,

[0045] S300: Open the outlet two of the three-way valve 6 to improve the utilization rate of the gas source.

[0046] Preferably, the anode purging and cathode purging in S200 are both pulse air purging, which is to blow out the residual moisture through the gas after shutdown to avoid the difficulty of second start-up under zero.

[0047] Further, the pressure into the stack in S200 is controlled to be 150kPa (absolute pressure), and the gas at this pressure can achieve a better purging state. Too large or too small gas cannot achieve ideal purging.

[0048] Specifically, after the experiment is completed, the hydrogen is automatically switched to nitrogen according to the set control program, and the permeated water on the anode side is purged. The water vapor mixture passes through the water separation element 4, the water is discharged to the atmosphere through the tail discharge valve 5, and the gas passes through the circulating pump. After passing through the circulating pump and taking away the water in the circulating pump, the three-way valve 6 can be opened to avoid the water returning to the anode again to form an invalid circulation. The water vapor mixture directly passes to the front end of the inlet throttle valve 8 to the cathode, and after the cathode is purged, it reaches the tail discharge throttle valve and is discharged to the atmosphere, thereby improving the utilization rate of the gas source. The wasted N2 passes through the three-way valve 6 and flows to the cathode to provide cathode purging. The cathode purging and anode purging are not in sequence, and most of the time they are carried out simultaneously. The cathode and the anode are purged by the same N2 gas source, which avoids the formation of a hydrogen-oxygen interface.

[0049] The embodiment also provides a fuel cell system, which comprises the stack 1 and the fuel cell engine shutdown purging system.

[0050] Compared with the prior art, the fuel cell engine shutdown purging system, the control method thereof and the fuel cell system provided by the present application can realize the gas purging of the anode and the cathode by adding the regulating valve 2 and the three-way valve 6, automatically controlling the switching of the gas and the flow direction of the gas according to the set program. Specifically, the present application has the following advantages:

[0051] 1. The liquid water in the circulating pump after shutdown can be reduced, and the cold start time can be shortened.

[0052] 2. A separate circulating gas branch is formed, nitrogen is used for purging, and the system architecture does not need to be greatly changed.

[0053] 3. The formation of a hydrogen-oxygen interface on the anode side is prevented, the corrosion of the C carrier is avoided, and the engine performance is improved.

[0054] 4. The utilization rate of hydrogen is increased, and the cost is reduced.

[0055] 5. Same gas source, same pressure, eliminate the occurrence of hydrogen and oxygen mutual string phenomenon.

[0056] 6. Reduce the artificial switching gas caused by artificial error factors.

[0057] Having described various embodiments of the disclosure above, the descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles, practical applications, or technical improvements of the technology in the market, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell engine shutdown purge system, characterized by, The fuel cell engine shutdown purging system comprises a regulating valve (2), a hydrogen nozzle (3), a water distribution device (4), a tail valve (5), a three-way valve (6), a hydrogen circulation device (7), an outlet air throttle (9) and an inlet air throttle (8), the inlet one of the regulating valve (2) is connected with a hydrogen source, the inlet two is connected with a nitrogen source, the outlet is connected with the inlet one of the hydrogen nozzle (3), the outlet of the hydrogen nozzle (3) is connected with the anode inlet of the electric pile (1), the anode outlet of the electric pile (1) is connected with the inlet of the water distribution device (4), the outlet one of the water distribution device (4) is connected with the inlet of the hydrogen circulation device (7), the outlet two is connected with the tail valve (5), the outlet of the hydrogen circulation device (7) is connected with the inlet of the three-way valve (6), the outlet one of the three-way valve (6) is connected with the inlet two of the hydrogen nozzle (3), the outlet two is connected with the inlet of the inlet air throttle (8), the outlet of the inlet air throttle (8) is connected with the cathode inlet of the electric pile (1), the inlet of the outlet air throttle (9) is connected with the cathode outlet of the electric pile (1); The outlet of the tail valve (5) is connected with a mixing point, and / or the outlet of the outlet air throttle (9) is connected with a mixing point. The fuel cell engine shutdown purging system further comprises a controller (10) which is in communication connection with the regulating valve (2) and the three-way valve (6) and is used for controlling the opening degree of the regulating valve (2) and the three-way valve (6).

2. The fuel cell engine stop purge system according to claim 1, wherein, The controller (10) is an upper computer.

3. The fuel cell engine stop purge system according to claim 1, wherein, The hydrogen nozzle (3) is provided with a high pressure sensor and a low pressure sensor.

4. The fuel cell engine stop purge system according to claim 1, wherein, The tail valve (5) is provided with a heating device.

5. A control method of a fuel cell engine stop purge system according to any one of claims 1 to 4, characterized by, The method comprises the following steps: S100: switching the control valve from hydrogen to nitrogen; S200: controlling the inlet pressure to be 140kPa-160kPa for anode purging and cathode purging; S300: opening the outlet two of the three-way valve (6).

6. The control method according to claim 5, characterized by The anode purging and the cathode purging in S200 are both pulse air purging.

7. The control method according to claim 5, characterized by, The inlet pressure in S200 is controlled to be 150kPa.

8. A fuel cell system characterized by comprising: The fuel cell engine shutdown purging system comprises an electric pile (1) and the fuel cell engine shutdown purging system according to any one of claims 1-4.

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