A fuel cell system and anode control method

Abstract

The present invention proposes a fuel cell system and an anode control method, wherein the anode flow channel of the fuel cell stack comprises a hydrogen gas circuit for supplying gas to the fuel cell stack, and the hydrogen gas circuit comprises a first gas circuit end and a second gas circuit end; the pipelines at the first gas circuit end and the second gas circuit end are simultaneously connected to a first three-way valve and a second three-way valve; the first three-way valve is connected to a hydrogen gas source used by the fuel cell stack; when the anode fuel cell stack is working, the first three-way valve and the second three-way valve switch the opening and closing states of their respective valve ports so that the hydrogen input end of the hydrogen gas circuit switches between the first gas circuit end and the second gas circuit end; in the blind-end mode, the present invention periodically changes the flow direction of the anode hydrogen to improve the accumulation of impurities downstream of the anode, reduce the local hydrogen supply shortage of the fuel cell, and reduce the number of emissions due to removal of impurities, thereby effectively reducing the frequency of hydrogen emissions in the "blind-end" mode and improving the utilization rate of hydrogen.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system and an anode control method. Background Art

[0002] A fuel cell is a device that converts chemical energy stored in fuel and oxidant into electrical energy. A fuel cell consists of a bipolar plate and a membrane electrode. Multiple fuel cell monomers are connected in series to form a fuel cell stack. The specific reaction process of a fuel cell is to inject hydrogen into the anode, where the hydrogen undergoes an oxidation reaction: H2-2e - =2H + ; Inject air into the cathode, and the oxygen in the air undergoes a reduction reaction at the cathode: O2+4H + +4e - =2H2O; To ensure the stable output of the fuel cell, the fuel cell system needs to include an air supply system and a hydrogen supply system. During operation, air is injected from the atmosphere to the cathode through a blower or air compressor, and the hydrogen supply system provides hydrogen to the anode. The general cathode adopts a direct discharge mode to discharge the unreacted exhaust gas and water directly from the stack, while the anode end has a hydrogen circulation mode and an anode "blind end" mode to ensure the utilization rate of hydrogen. The circulation mode requires a circulation pump, which increases the complexity of the system and the power consumption of the system. The anode "blind end" mode system simplifies and reduces the power consumption of the system. In the "blind end" mode, as the reaction of hydrogen proceeds, impurities such as nitrogen and water that penetrate from the cathode to the anode continue to accumulate at the anode. Since the fuel gas supplied to the anode is almost completely consumed, the concentration of impurities accumulated downstream of the anode closer to the blind end is higher, resulting in insufficient local fuel supply and a drop in the voltage of the fuel cell. Therefore, it is necessary to periodically open the anode gas outlet solenoid valve of the "blind end" to remove the impurities accumulated at the anode and restore the voltage of the fuel cell.

[0003] Removing impurities from the anode requires frequent opening of the anode exhaust valve to discharge the impurity gas. This operation will also cause some hydrogen to be discharged, resulting in a decrease in utilization. Summary of the invention

[0004] The present invention proposes a fuel cell system and an anode control method, which periodically changes the flow direction of anode hydrogen in a blind-end mode to improve the accumulation of impurities downstream of the anode, reduce the phenomenon of insufficient local hydrogen supply in the fuel cell, and reduce the number of emissions for removing impurities, thereby effectively reducing the frequency of hydrogen emissions in the "blind-end" mode and improving the utilization rate of hydrogen.

[0005] The present invention adopts the following technical solutions.

[0006] A fuel cell system, wherein the anode of the fuel cell stack (10) uses hydrogen as a fuel cell reaction medium; the anode flow channel of the stack comprises a hydrogen gas path for supplying gas to the stack, the hydrogen gas path comprises a first gas path end (51) and a second gas path end (52); the pipelines at the first gas path end and the second gas path end are simultaneously connected to a first three-way valve (22) and a second three-way valve (23); the first three-way valve is connected to a hydrogen gas source (20) used by the stack; when the anode of the stack is working, the first three-way valve and the second three-way valve switch the opening and closing states of their respective valve ports, so that the hydrogen input end of the hydrogen gas path switches between the first gas path end and the second gas path end.

[0007] The second three-way valve is connected to the tail gas discharge end of the fuel cell stack;

[0008] When the hydrogen input end of the anode of the stack is switched to the first end of the gas circuit, the anode flow channel of the stack is in a forward gas supply state, and the second end of the gas circuit is switched to the exhaust gas discharge end of the hydrogen gas circuit and communicates with the exhaust gas discharge end through the second three-way valve;

[0009] When the hydrogen input end of the anode of the fuel cell stack is switched to the second end of the gas circuit, the anode flow channel of the fuel cell stack is in a reverse gas supply state, and the first end of the gas circuit is switched to the exhaust gas discharge end of the hydrogen gas circuit and communicated with the tail gas discharge end through the second three-way valve.

[0010] The hydrogen gas source is a hydrogen storage device or a hydrogen production device; the valve ports of the first three-way valve and the second three-way valve both include a main valve port, a normally open valve port, and a normally closed valve port; the hydrogen output end of the hydrogen gas source is communicated with the main valve port of the first three-way valve via a pressure reducing and stabilizing valve (21); the tail gas discharge end of the fuel cell stack is communicated with the main valve port of the second three-way valve via a tail exhaust valve (25) and a gas-water separator (24).

[0011] The normally open valve port (26) of the first three-way valve and the normally closed valve port (28) of the second three-way valve are in communication with the first end of the gas circuit; the normally open valve port (29) of the second three-way valve and the normally closed valve port (27) of the first three-way valve are in communication with the first end of the gas circuit.

[0012] When the anode flow channel of the fuel cell stack is in a forward gas supply state, the normally open valve port (26) of the first three-way valve and the normally open valve port (29) of the second three-way valve are opened, and the normally closed valve port (27) of the first three-way valve and the normally closed valve port (28) of the second three-way valve are closed, and the anode of the fuel cell stack receives hydrogen from the normally open valve port (26) of the first three-way valve, and discharges exhaust gas from the normally open valve port (29) of the second three-way valve to the gas-water separator (24);

[0013] When the anode flow channel of the fuel cell stack is in a reverse gas supply state, the normally open valve port (26) of the first three-way valve and the normally open valve port (29) of the second three-way valve are closed, and the normally closed valve port (27) of the first three-way valve and the normally closed valve port (28) of the second three-way valve are opened, and the anode of the fuel cell stack receives hydrogen from the normally closed valve port (27) of the first three-way valve and discharges exhaust gas from the normally closed valve port (28) of the second three-way valve to the gas-water separator (24).

[0014] When the hydrogen from the hydrogen source is input into the anode of the fuel cell stack, the impurities at the hydrogen input end of the hydrogen gas path are cleared by the flowing gas pressure of the hydrogen.

[0015] The tail exhaust valve (25), the first three-way valve, and the second three-way valve are all solenoid valves.

[0016] A method for controlling an anode of a fuel cell system. The fuel cell system described above periodically switches the opening and closing states of the valve ports of the first three-way valve and the second three-way valve during operation of the anode, so that the gas supply state of the fuel cell stack is periodically switched between a forward gas supply state and a reverse gas supply state, so that when the hydrogen gas source supplies gas to the anode of the fuel cell stack, the impurities at the anode of the fuel cell stack are periodically purged with hydrogen after the pressure is regulated by a pressure reducing and stabilizing valve, thereby reducing the accumulation of impurities in the anode hydrogen gas path.

[0017] The tail exhaust valve is in a normally closed state to enable the anode flow channel to operate in a blind end mode, and the gas-water separator is used to separate water from the exhaust gas; when the amount of impurities accumulated in the anode hydrogen gas path is too much and causes the fuel cell voltage to drop, the tail exhaust valve opens to allow the anode of the stack to discharge the exhaust gas through the tail exhaust valve at the blind end, while increasing the air flow rate of the anode hydrogen gas path to discharge impurities.

[0018] The advantage of the present invention is that it provides an anode control method, which can realize forward and reverse gas supply to the fuel cell stack and periodic purging in the anode direction of the fuel cell stack, thereby preventing the phenomenon that impurities accumulate downstream of the anode gas supply when the fuel cell stack is supplied with gas in a single direction in the traditional blind-end operation mode, and can reduce the number of anode emissions and improve the utilization rate of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0020] Attached Figure 1 It is a schematic diagram of the structural principle of a single fuel cell;

[0021] Attached Figure 2 It is a schematic diagram of the change of the impurity accumulation amount from the anode flow channel inlet to the downstream when the fuel cell is running;

[0022] Attached Figure 3It is a working schematic diagram when the anode flow channel of the battery stack is in a forward gas supply state;

[0023] Attached Figure 4 It is a working schematic diagram when the anode flow channel of the battery stack is in a reverse gas supply state;

[0024] Attached Figure 5 It is a schematic diagram of the change of anode impurity concentration over time in the scheme of the present invention and the traditional scheme;

[0025] In the figure: 1-proton exchange membrane; 2-cathode catalyst layer; 3-anode catalyst layer; 4-cathode diffusion layer; 5-anode diffusion layer; 6-cathode flow channel; 7-anode flow channel;

[0026] 10-cell stack; 11-air filter; 12-air compressor / blower; 13-humidifier; 20-hydrogen gas source; 21-pressure reducing and stabilizing valve; 22-first three-way valve; 23-second three-way valve; 24-gas-water separator; 25-tail exhaust valve; 26-normally open valve port of the first three-way valve; 27-normally closed valve port of the first three-way valve; 28-normally closed valve port of the second three-way valve; 29-normally open valve port of the second three-way valve;

[0027] 51-the first end of the gas circuit; 52-the second end of the gas circuit. DETAILED DESCRIPTION

[0028] As shown in the figure, a fuel cell system is provided, wherein the anode of the fuel cell stack 10 uses hydrogen as the fuel cell reactant; the anode flow channel 7 of the stack includes a hydrogen gas circuit for supplying gas to the stack, and the hydrogen gas circuit includes a first gas circuit end 51 and a second gas circuit end 52; the pipelines at the first gas circuit end and the second gas circuit end are simultaneously connected to a first three-way valve 22 and a second three-way valve 23; the first three-way valve is connected to a hydrogen gas source 20 used by the stack; when the anode of the stack is working, the first three-way valve and the second three-way valve switch the opening and closing states of their respective valve ports to switch the hydrogen input end of the hydrogen gas circuit between the first gas circuit end and the second gas circuit end.

[0029] The second three-way valve is connected to the tail gas discharge end of the fuel cell stack;

[0030] When the hydrogen input end of the anode of the stack is switched to the first end of the gas circuit, the anode flow channel of the stack is in a forward gas supply state, and the second end of the gas circuit is switched to the exhaust gas discharge end of the hydrogen gas circuit and communicates with the exhaust gas discharge end through the second three-way valve;

[0031] When the hydrogen input end of the anode of the fuel cell stack is switched to the second end of the gas circuit, the anode flow channel of the fuel cell stack is in a reverse gas supply state, and the first end of the gas circuit is switched to the exhaust gas discharge end of the hydrogen gas circuit and communicated with the tail gas discharge end through the second three-way valve.

[0032] The hydrogen gas source is a hydrogen storage device or a hydrogen preparation device; the valve ports of the first three-way valve and the second three-way valve include a main valve port, a normally open valve port, and a normally closed valve port; the hydrogen output end of the hydrogen gas source is connected to the main valve port of the first three-way valve via a pressure reducing and stabilizing valve 21; the tail gas discharge end of the fuel cell stack is connected to the main valve port of the second three-way valve via a tail exhaust valve 25 and a gas-water separator 24.

[0033] The normally open valve port 26 of the first three-way valve and the normally closed valve port 28 of the second three-way valve are communicated with the first end of the gas circuit; the normally open valve port 29 of the second three-way valve and the normally closed valve port 27 of the first three-way valve are communicated with the first end of the gas circuit.

[0034] When the anode flow channel of the stack is in a forward gas supply state, the normally open valve port 26 of the first three-way valve and the normally open valve port 29 of the second three-way valve are opened, and the normally closed valve port 27 of the first three-way valve and the normally closed valve port 28 of the second three-way valve are closed, and the anode of the stack of the fuel cell receives hydrogen from the normally open valve port 26 of the first three-way valve, and discharges the exhaust gas from the normally open valve port 29 of the second three-way valve to the gas-water separator 24;

[0035] When the anode flow channel of the fuel cell stack is in a reverse gas supply state, the normally open valve port 26 of the first three-way valve and the normally open valve port 29 of the second three-way valve are closed, and the normally closed valve port 27 of the first three-way valve and the normally closed valve port 28 of the second three-way valve are opened, and the anode of the fuel cell stack receives hydrogen from the normally closed valve port 27 of the first three-way valve, and discharges the exhaust gas from the normally closed valve port 28 of the second three-way valve to the gas-water separator 24.

[0036] When the hydrogen from the hydrogen source is input into the anode of the fuel cell stack, the impurities at the hydrogen input end of the hydrogen gas path are cleared by the flowing gas pressure of the hydrogen.

[0037] The tail exhaust valve 25, the first three-way valve and the second three-way valve are all solenoid valves.

[0038] A method for controlling an anode of a fuel cell system. The fuel cell system described above periodically switches the opening and closing states of the valve ports of the first three-way valve and the second three-way valve during operation of the anode, so that the gas supply state of the fuel cell stack is periodically switched between a forward gas supply state and a reverse gas supply state, so that when the hydrogen gas source supplies gas to the anode of the fuel cell stack, the impurities at the anode of the fuel cell stack are periodically purged with hydrogen after the pressure is regulated by a pressure reducing and stabilizing valve, thereby reducing the accumulation of impurities in the anode hydrogen gas path.

[0039] The tail exhaust valve is in a normally closed state to enable the anode flow channel to operate in a blind end mode, and the gas-water separator is used to separate water from the exhaust gas; when the amount of impurities accumulated in the anode hydrogen gas path is too much and causes the fuel cell voltage to drop, the tail exhaust valve opens to allow the anode of the stack to discharge the exhaust gas through the tail exhaust valve at the blind end, while increasing the air flow rate of the anode hydrogen gas path to discharge impurities.

[0040] from Figure 5 It can be seen that after adopting the solution of the present invention (dashed line in the figure), the exhaust frequency is significantly reduced and the impurity concentration is also significantly reduced.

Claims

1. A fuel cell system, characterized in that: The anode of the fuel cell stack (10) uses hydrogen as a fuel cell reaction medium; the anode flow channel of the stack includes a hydrogen gas path for supplying gas to the stack, and the hydrogen gas path includes a first gas path end and a second gas path end; the pipelines at the first gas path end and the second gas path end are simultaneously connected to a first three-way valve (22) and a second three-way valve (23); the first three-way valve is in communication with a hydrogen gas source (20) used by the stack; when the anode of the stack is working, the first three-way valve and the second three-way valve switch the opening and closing states of their respective valve ports, so that the hydrogen input end of the hydrogen gas path switches between the first gas path end and the second gas path end; The second three-way valve is connected to the tail gas discharge end of the fuel cell stack; When the hydrogen input end of the anode of the stack is switched to the first end of the gas circuit, the anode flow channel of the stack is in a forward gas supply state, and the second end of the gas circuit is switched to the exhaust gas discharge end of the hydrogen gas circuit and communicates with the exhaust gas discharge end through the second three-way valve; When the hydrogen input end of the anode of the stack is switched to the second end of the gas circuit, the anode flow channel of the stack is in a reverse gas supply state, and the first end of the gas circuit is switched to the exhaust gas discharge end of the hydrogen gas circuit and communicates with the exhaust gas discharge end through the second three-way valve; The hydrogen gas source is a hydrogen storage device or a hydrogen production device; the valve ports of the first three-way valve and the second three-way valve both include a main valve port, a normally open valve port, and a normally closed valve port; the hydrogen output end of the hydrogen gas source is communicated with the main valve port of the first three-way valve via a pressure reducing and stabilizing valve (21); the tail gas discharge end of the fuel cell stack is communicated with the main valve port of the second three-way valve via a tail discharge valve (25) and a gas-water separator (24); The normally open valve port (26) of the first three-way valve and the normally closed valve port (28) of the second three-way valve are in communication with the first end of the gas circuit; the normally open valve port (29) of the second three-way valve and the normally closed valve port (27) of the first three-way valve are in communication with the first end of the gas circuit; An anode control method for a fuel cell system, wherein the anode of the fuel cell system periodically switches the opening and closing states of the valve ports of the first three-way valve and the second three-way valve when the anode is in operation, so that the gas supply state of the fuel cell stack is periodically switched between the forward gas supply state and the reverse gas supply state, so that when the hydrogen gas source supplies gas to the anode of the fuel cell stack, the impurities at the anode of the fuel cell stack are periodically purged with the hydrogen after the pressure is regulated by the pressure reducing and stabilizing valve, thereby reducing the accumulation of impurities in the anode hydrogen gas path.

2. A fuel cell system according to claim 1, characterized in that: When the anode flow channel of the fuel cell stack is in a forward gas supply state, the normally open valve port (26) of the first three-way valve and the normally open valve port (29) of the second three-way valve are opened, and the normally closed valve port (27) of the first three-way valve and the normally closed valve port (28) of the second three-way valve are closed, and the anode of the fuel cell stack receives hydrogen from the normally open valve port (26) of the first three-way valve, and discharges exhaust gas from the normally open valve port (29) of the second three-way valve to the gas-water separator (24); When the anode flow channel of the fuel cell stack is in a reverse gas supply state, the normally open valve port (26) of the first three-way valve and the normally open valve port (29) of the second three-way valve are closed, and the normally closed valve port (27) of the first three-way valve and the normally closed valve port (28) of the second three-way valve are opened, and the anode of the fuel cell stack receives hydrogen from the normally closed valve port (27) of the first three-way valve and discharges exhaust gas from the normally closed valve port (28) of the second three-way valve to the gas-water separator (24).

3. A fuel cell system according to claim 1, characterized in that: When the hydrogen from the hydrogen source is input into the anode of the fuel cell stack, the impurities at the hydrogen input end of the hydrogen gas path are cleared by the flowing gas pressure of the hydrogen.

4. A fuel cell system according to claim 1, characterized in that: The tail exhaust valve (25), the first three-way valve, and the second three-way valve are all solenoid valves.

5. A fuel cell system according to claim 1, characterized in that: The tail exhaust valve is in a normally closed state to enable the anode flow channel to operate in a blind end mode, and the gas-water separator is used to separate water from the exhaust gas; when the amount of impurities accumulated in the anode hydrogen gas path is too much and causes the fuel cell voltage to drop, the tail exhaust valve opens to allow the anode of the stack to discharge the exhaust gas through the tail exhaust valve at the blind end, while increasing the air flow rate of the anode hydrogen gas path to discharge impurities.

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