TWI772076B - High-efficiency industrial waste hydrogen power generation system and control method thereof - Google Patents

Abstract

The present invention is an high-efficiency fuel cell system using industrial waste hydrogen and its control method. The system determines the operating voltage of the stack module by measuring the hydrogen concentration fed into the stack module. Therefore, the stack module does not need to undergo an electrochemical reaction in the case of hydrogen deficiency, so as to avoid damage to the stack module, and the stack module allows to generate the maximum electric energy under the maximum reaction efficiency. At the same time, by judging the hydrogen concentration of the remaining fuel gas to determine the timing of discharging the remaining fuel gas, the effect of maintaining the safety of the surrounding environment and protecting the environment can also be achieved.

Description

High-efficiency industrial waste hydrogen power generation system and control method thereof

The present invention relates to a fuel cell system, especially a fuel cell system using industrial waste hydrogen as fuel gas.

In a fuel cell system, hydrogen and air are injected into the stack, and the stack undergoes electrochemical reactions to generate electricity. When the fuel cell system is used in conjunction with other industrial systems, the industrial waste hydrogen generated during the operation of other industrial systems is often used as the fuel for the fuel cell system of the prior art.

In the design of the fuel cell system, the generation of electric current means that the electrochemical reaction continues, and hydrogen will be consumed to carry out the oxidation reaction with oxygen. The bulk catalyst produces an oxidative reverse reaction, which causes damage to the battery stack, so excess hydrogen must be given to avoid the battery stack being damaged due to lack of hydrogen during the electrochemical reaction process, and giving excess air and hydrogen can also ensure sufficient power generation capacity. . However, the characteristics of industrial waste hydrogen are low purity and unstable supply flow, so it is easy to cause hydrogen deficiency due to unstable hydrogen supply, and then damage the battery stack. Moreover, it is also easy to cause unstable output voltage due to unstable hydrogen supply.

In view of this, the present invention solves the system problems caused by the instability of the purity and flow of industrial waste hydrogen.

In order to achieve the above-mentioned purpose of the invention, the technical means adopted in the present invention is to provide a fuel cell system, which includes: a stack module, which has an anode intake end, an anode exhaust end, a cathode intake end, and a cathode exhaust end; a fuel intake assembly, which is connected with the anode intake end of the stack module, for providing fuel gas into the stack module, and has a fuel inlet sensor; a an air component, which is connected with the cathode air intake end and the cathode exhaust end of the stack module, and is used to provide air to enter the stack module; a fuel exhaust component, which is connected to the anode of the stack module The exhaust end is connected to receive the residual fuel gas after the reaction of the stack module. The fuel exhaust component includes a return valve, and the return valve is connected to the anode exhaust end of the stack module; a control unit , which forms an electrical connection with the stack module, the fuel intake assembly, and the fuel exhaust assembly, wherein the control unit performs the following steps: a. By the amount of the fuel intake sensor of the fuel intake assembly Measured data to obtain the hydrogen concentration of the fuel gas supplied by the fuel intake assembly; b. According to the measured hydrogen concentration, determine the operating voltage of the stack module, so that the stack module operates at the determined operating voltage Start operation; c. Determine the hydrogen concentration of the remaining fuel gas to be discharged; d. According to the hydrogen concentration determined in step c, determine whether the remaining fuel gas has reached a dischargeable level; e1. If the determination in step d is no, then the remaining fuel gas is retained in the stack module or open the return valve to direct the residual fuel gas into the cathode inlet, or direct the residual fuel gas into a catalytic converter, or direct the residual fuel gas back to the cathode In the anode inlet end of the stack module.

The advantage of the present invention is that, by sensing the hydrogen concentration of the intake air, the operating voltage suitable for the stack module is calculated, and the stack module is operated by fixing the operating voltage of the stack module. In the case of a sudden drop in hydrogen concentration, only the output current is reduced, which also means that the electrochemical reaction of the stack module is reduced, avoiding the consumption of the structure of the stack module for electrochemical reaction, and achieving the effect of protecting the stack module. It also allows the stack module to generate the maximum electrical energy at the maximum reaction efficiency.

10: stack module

11: Anode intake end

12: Anode exhaust end

13: Cathode intake end

14: Cathode exhaust end

15: Water inlet

16: Drain end

101: Converter

20: Fuel intake assembly

21: Flowmeter

22: Storage tank

23: Fuel inlet sensor

24: Intake valve group

241: Feed solenoid valve

30: Air components

31: Humidifier

32: Air compressor

33: Air flow meter

40: Water circulation components

41: water pump

42: Thermostat

43: Radiator

50, 50A, 50B, 50C: Fuel Exhaust Assembly

51, 51A, 51B, 51C: Fuel outlet sensor

52, 52A, 52C: Drain valve

52B, 53, 53A, 53C: return valve

54A, 54C: catalytic converter

55B, 55C: return pump

60: Control unit

1 is a system architecture diagram of a first embodiment of the fuel cell system of the present invention; FIG. 2 is a block diagram of some components of the fuel cell system of the present invention; FIG. 3 is a flowchart of a control method of the fuel cell system of the present invention 4 is a comparison diagram of the voltage and current of the fuel cell system of the present invention under different hydrogen concentrations; FIG. 5 is a system architecture diagram of the second embodiment of the fuel cell system of the present invention; FIG. 6 is the fuel cell system of the present invention. The system architecture diagram of the third embodiment of FIG. 7 is the system architecture diagram of the fourth embodiment of the fuel cell system of the present invention.

The technical means adopted by the present invention to achieve the predetermined purpose of the present invention are further described below in conjunction with the drawings and the embodiments of the present invention, wherein the drawings are simplified for the purpose of illustration only, and describe the relationship between the elements and components of the present invention. to illustrate the structure or method invention of the present invention, therefore, the elements shown in the figures are not presented in the actual number, actual shape, actual size and actual scale, and the size or size ratio has been exaggerated or simplified to provide a better description. , has been selectively designed and configured actual quantity, actual shape or actual size ratio, while the detailed component layout may be more complex.

Please refer to FIG. 1 and FIG. 2 , the fuel cell system of the present invention includes a stack module 10 , a fuel intake assembly 20 , an air assembly 30 , a water circulation assembly 40 , a fuel exhaust assembly 50 , and a control unit 60.

The aforementioned stack module 10 has an anode intake end 11 , an anode exhaust end 12 , a cathode intake end 13 , a cathode exhaust end 14 , a water intake end 15 , and a drain end 16 . The gas enters the stack module 10 from the anode intake end 11 , the air enters the stack module 10 from the cathode intake end 13 , generates electrochemical reaction in the stack module 10 to generate electricity, and the water enters the electricity through the water intake end 15 . The stack module 10 is used to cool the system, then the anode exhaust gas is discharged from the anode exhaust end 12, and the cathode exhaust gas is exhausted from the cathode exhaust end 14. The stack module 10 is connected to an external device to provide the generated power to the outside The power output from the stack module 10 can be converted into AC power through an inverter 101 and then provided to external devices.

The aforementioned fuel intake assembly 20 is connected to the anode intake end 11 of the stack module 10 , and is used to supply industrial waste hydrogen used as fuel into the stack module 10 . The fuel intake assembly 20 includes a flow meter 21, a storage tank 22, and a fuel inlet sensor 23. Industrial waste hydrogen is fed into the storage tank 22 of the fuel intake assembly, and the flow meter 21 and the fuel Sensing number of entrance sensor 23 According to the data, the flow rate and hydrogen concentration of industrial waste hydrogen sent into the storage tank 22 are obtained. In one embodiment, the fuel inlet sensor 23 directly detects the hydrogen concentration of the fed gas; in another embodiment, the fuel inlet sensor 23 is a pressure sensor that detects the The amount of pressure change of the fed gas is used to estimate the hydrogen concentration in the fed gas. In one embodiment, the fuel intake assembly 20 is connected to the anode intake end 11 through an intake valve group 24 .

The aforementioned air component 30 is connected to the cathode inlet end 13 and the cathode exhaust end 14 of the stack module 10 , and the air component 30 sends air from the cathode inlet end 13 to the stack module 10 . The excess air after the reaction of the module 10 is discharged from the cathode exhaust end 14 . In one embodiment, the air component 30 is connected to the cathode inlet end 13 and the cathode exhaust end 14 through a humidifier 31, thereby adjusting the humidity of the intake air, so that the incoming air can provide the electricity. The stack module 10 has an appropriate operating humidity, and thereby adjusts the humidity of the exhaust gas, so as to increase its relative humidity to further reduce its risk. In one embodiment, the air assembly 30 includes an air compressor 32 and an air flow meter 33 . The air compressor 32 is used for driving air into the stack module 10 , and the air flow meter 33 is used for driving air into the stack module 10 . to sense instant air flow.

The aforementioned water circulation assembly 40 is connected to the water inlet end 15 and the drain end 16 of the stack module 10 , and the water circulation assembly 40 is used to provide appropriate water to the stack module 10 for cooling the stack module 10 . . In one embodiment, the water circulation assembly 40 includes a water pump 41, a thermostat 42 and a radiator 43. The water pump 41 sends water into the water inlet 15 of the stack module 10. The thermostat 42 and The radiator 43 receives the water discharged from the drain end 16 , adjusts the temperature, and then recirculates it back to the water pump 41 .

The aforementioned fuel exhaust assembly 50 is connected to the anode exhaust end 12 of the stack module 10 for receiving the remaining fuel gas after the reaction. In one embodiment, the fuel exhaust assembly 50 includes an exhaust valve 52 for controlling whether to exhaust the remaining fuel gas from the anode exhaust end 12 or not.

The aforementioned control unit 60 is electrically connected to the stack module 10 , the fuel intake assembly 20 , and the fuel exhaust assembly 50 . In one embodiment, the control unit 60 is electrically connected to the fuel inlet sensor 23 and the flow meter 21 .

Please refer to FIG. 3 in conjunction with FIGS. 1 and 2 , the control method of the fuel cell system of the present invention during operation includes the following steps:

Measure the hydrogen concentration (S10): when the industrial waste hydrogen enters the fuel intake assembly 20, the hydrogen concentration in the storage tank 22 is obtained by the sensing data of the flow meter 21 and the fuel inlet sensor 23 .

Determining the operating voltage of the stack module 10 according to the hydrogen concentration ( S20 ): the control unit 60 determines the operating voltage of the stack module 10 according to the obtained hydrogen concentration entering the fuel intake assembly 20 , so that the stack The module 10 starts to operate at the determined operating voltage.

Determining the hydrogen concentration of the exhaust gas (S30): After the stack module 10 is reacted, the remaining fuel gas is to be discharged through the anode exhaust end 12, according to the fuel exhaust component 50 received from the anode exhaust end 12 of the remaining fuel gas to determine the hydrogen concentration in the remaining fuel gas to be discharged. In one embodiment, the fuel exhaust assembly 50 may include a fuel outlet sensor 51 , and the remaining fuel to be discharged from the stack module 10 can be obtained by sensing data of the fuel outlet sensor 51 . The hydrogen concentration in the gas is reported and notified to the control unit 60. The fuel outlet sensor 51 can directly detect the hydrogen concentration in the gas, or it can be used as a pressure sensor to estimate the hydrogen concentration through changes in air pressure; in another embodiment , the control unit 60 calculates the amount of hydrogen consumed by the stack module 10 during operation by using the current produced by the stack module 10 during operation, and then matches the amount of the fuel intake assembly 20 The measured flow rate and hydrogen concentration further estimate the hydrogen concentration in the remaining fuel gas to be discharged; in another embodiment, the fuel exhaust assembly 50 includes the fuel outlet sensor 51, the control unit 60 Except for receiving In addition to receiving the hydrogen concentration in the remaining fuel gas obtained from the fuel outlet sensor, the aforementioned method of measuring current is also used to estimate the hydrogen concentration in the remaining fuel gas. The control unit 60 compares the sensed value with the estimated value. After the value is determined, the hydrogen concentration in the remaining fuel gas to be discharged can be judged.

Determining whether the discharged exhaust gas has reached the dischargeable level (S40): If the hydrogen concentration in the remaining fuel gas is greater than the standard value, the hydrogen concentration around the system may be too high to cause explosion danger, or cause environmental pollution and other problems after discharge. , therefore, the control unit 60 needs to determine whether the residual fuel gas has reached a dischargeable level according to the hydrogen concentration in the residual fuel gas determined in the step S30, if so, go to the step S50, if not, go to the step S50 S60.

Exhaust gas discharge (S50): If the control unit 60 determines that the hydrogen concentration in the remaining fuel gas has reached the standard value, the discharge valve 52 can be opened to discharge the remaining fuel gas to the outside, and the stack module 10 can be pushed together during discharge. In order to facilitate the water after the reaction is discharged from the drainage end 16. In one embodiment, the discharge valve 52 can be controlled to open intermittently at a certain frequency to discharge the remaining fuel gas. In one embodiment, the outlet end of the discharge valve 52 is connected to the humidifier 31 , and the residual fuel gas system passes through the humidifier 31 and then is discharged to the outside.

Perform exhaust gas post-treatment (S60): If the control unit 60 determines that the hydrogen concentration in the remaining fuel gas is greater than the standard value, it can perform exhaust gas after-treatment to prevent the remaining fuel gas that does not meet the standard from being discharged into the atmosphere. In one embodiment, the discharge valve 52 is closed, so that the remaining fuel gas remains in the stack module 10 for reaction, so as to consume the hydrogen therein, thereby effectively reducing the hydrogen concentration of the remaining fuel gas.

Please refer to FIG. 4 , under the premise of maintaining a fixed operating voltage in the present invention, it can be seen from the graph in FIG. 4 that even if the hydrogen concentration changes (that is, when the hydrogen concentration in the supplied industrial waste hydrogen suddenly changes) sag or swell), only the output current changes, even if the output current drops The lowest value means that the electrochemical reaction in the stack module 10 will no longer be carried out, and there will be no problem of consuming the structure of the stack module 10 , which can ensure that the stack module 10 will not be caused by the change of the hydrogen concentration. The damage of the stack module can also make the stack module generate the maximum electric energy under the maximum reaction efficiency. Therefore, the system and the control method of the present invention can effectively protect the fuel cell system.

The following uses different embodiments to describe the variation of the system structure and the variation of the steps of the cooperative control method of the present invention, but the present invention is not limited thereto.

Referring to FIG. 1 , in one embodiment, the fuel exhaust assembly 50 includes a return valve 53 , and the return valve 53 is connected to the anode exhaust end 12 of the stack module 10 and the cathode intake end 13, when it is determined in step S50 that the hydrogen concentration in the remaining fuel gas is greater than the standard value, then in step S60, the recirculation valve 53 is opened, and the remaining fuel gas is introduced into the cathode inlet end 13, by means of which the recirculation valve 53 is opened. The residual hydrogen in the stack module 10 is burnt out by the cathode catalyst, and the hydrogen is mixed into the air and enters the cathode inlet 13, which can also contribute to the reduction of the cathode catalyst, maintain the performance of the fuel cell, and improve the performance of the fuel cell. Extend fuel cell life. In one embodiment, a first standard value and a second standard value can be set, the first standard value is smaller than the second standard value, and when the hydrogen concentration in the remaining fuel gas is greater than the second standard value, the In step S60, both the discharge valve 52 and the return valve 53 are closed, so that the remaining fuel gas remains in the stack module 10 for reaction, so as to consume the hydrogen therein; when the hydrogen concentration in the remaining fuel gas is between the When the first standard value is between the second standard value, the process proceeds to step S60, and the return valve 53 is opened to introduce the remaining fuel gas into the cathode inlet end 13; when the hydrogen concentration in the remaining fuel gas is less than the first standard If the value is equal, then go to step S50, and open the discharge valve 52 to discharge the remaining fuel gas.

Referring to FIG. 5, in one embodiment, the fuel exhaust assembly 50A includes the fuel outlet sensor 51A, a discharge valve 52A, a return valve 53A, and a catalytic converter 54A. The return valve 53A is connected between the anode exhaust end 12 of the stack module 10 and the catalytic converter 54A. When it is determined in step S50 that the hydrogen concentration in the remaining fuel gas is greater than the standard value, then in step S60, the return valve 53A is opened, and the remaining fuel gas is introduced into the catalytic converter 54A for combustion to convert the hydrogen After it is exhausted as much as possible, it is further discharged into the atmosphere. The return valve 53 can be controlled to open intermittently at a certain frequency to introduce the remaining fuel gas into the catalytic converter 54A. In one embodiment, a first standard value and a second standard value can be set, the first standard value is smaller than the second standard value, and when the hydrogen concentration in the remaining fuel gas is greater than the second standard value, the In step S60, both the discharge valve 52A and the return valve 53A are closed, so that the remaining fuel gas remains in the stack module 10 for reaction to consume the hydrogen therein; when the hydrogen concentration in the remaining fuel gas is between the When the first standard value is between the second standard value, the process proceeds to step S60, and the return valve 53A is opened to introduce the remaining fuel gas into the catalytic converter 54A for combustion; when the hydrogen concentration in the remaining fuel gas is less than the first When the value is a standard value, the process goes to step S50, and the discharge valve 52A is opened to discharge the remaining fuel gas.

Please refer to FIG. 6 , the fuel exhaust assembly 50B includes the fuel outlet sensor 51B, the return valve 52B and a return pump 55B. The return valve 52B can be connected to the outside, connected to the humidifier 31, Or connected to the cathode inlet end 13 of the stack module 10, and the return pump 55B is connected between the anode exhaust end 12 and the anode inlet end 11 of the stack module 10, in step S50 In step S60, it is judged that the hydrogen concentration in the remaining fuel gas is greater than the standard value, then in step S60, the return pump 55B is turned on, and the remaining fuel gas is led back to the anode inlet 11 again, so as to return to the stack module 10 reaction in. In one embodiment, a first standard value and a second standard value can be set, the first standard value is smaller than the second standard value, and when the hydrogen concentration in the remaining fuel gas is greater than the second standard value, the In step S60, the recirculation valve 52B and the recirculation pump 55B are both closed, so that the remaining fuel gas remains in the stack module 10 for reaction to consume the hydrogen therein; when the hydrogen concentration in the remaining fuel gas is between the When the value is between the first standard value and the second standard value, step S60 is entered, and the return pump 55B is turned on to guide the remaining fuel gas back into the anode inlet 11; when the hydrogen concentration in the remaining fuel gas When the value is less than the first standard value, the process proceeds to step S50, and the return valve 52B is opened to discharge the remaining fuel gas.

Referring to FIG. 7 , the fuel exhaust assembly 50C includes the fuel outlet sensor 51C, the discharge valve 52C, the return valve 53C, the catalytic converter 54C, and the return pump 55C. The return valve 53C is connected between the anode exhaust end 12 and the catalytic converter 54C, the catalytic converter 54C is connected between the return valve 53C and the cathode intake end 13, and the return pump 55C is connected to the anode between the exhaust end 12 and the anode intake end 11 . In one embodiment, a first standard value, a second standard value and a third standard value can be set, the second standard value is between the first standard value and the third standard value, the third standard value The standard value is greater than the second standard value and the first standard value, and when the hydrogen concentration in the remaining fuel gas is greater than the third standard value, then enter step S60, the discharge valve 52C and the return pump 55C are both closed, The remaining fuel gas is left in the stack module 10 for reaction to consume the hydrogen therein; when the hydrogen concentration in the remaining fuel gas is between the second standard value and the third standard value, enter the step S60, turn on the return pump 55C to guide the remaining fuel gas back into the anode inlet 11; when the hydrogen concentration in the remaining fuel gas is between the first standard value and the second standard value, enter the Step S60, open the return valve 53C to introduce the remaining fuel gas into the catalytic converter 54C for combustion; when the hydrogen concentration in the remaining fuel gas is less than the first standard value, then go to step S50, and open the discharge valve 52C to discharge the remaining fuel gas.

Further, please refer to FIG. 5 , the intake valve group 24 of the fuel intake assembly 20 includes a feed solenoid valve 241 , and the feed solenoid valve 241 is connected to the storage tank 22 and the anode intake end 11 Meanwhile, the control unit 60 further decides to open or close the feed solenoid valve 241 according to the hydrogen concentration in the stack module 10 .

The above descriptions are only the embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed as above by the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field, Within the scope of not departing from the technical solution of the present invention, when the technical content disclosed above can be used to make some changes or modifications to equivalent embodiments with equivalent changes, but any content that does not depart from the technical solution of the present invention, according to the technical essence of the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

Claims (17)

A fuel cell system includes: a stack module, which has an anode intake end, an anode exhaust end, a cathode intake end, and a cathode exhaust end; a fuel intake assembly, which is connected with the The anode inlet end of the stack module is connected to provide fuel gas into the stack module, and has a fuel inlet sensor; an air component, which is connected to the cathode inlet end of the stack module and the The cathode exhaust end is connected to provide air to enter the stack module; a fuel exhaust component is connected to the anode exhaust end of the stack module for receiving the reaction of the stack module. the remaining fuel gas, the fuel exhaust assembly includes a return valve, the return valve is connected to the anode exhaust end of the stack module; a control unit, which is connected with the stack module, the fuel intake assembly, and the The fuel exhaust assembly forms an electrical connection, wherein the control unit performs the following steps: a. Obtaining the hydrogen gas of the fuel gas supplied by the fuel intake assembly according to the sensing data of the fuel inlet sensor of the fuel intake assembly concentration; b. According to the obtained hydrogen concentration, determine the operating voltage of the stack module, so that the stack module starts to operate at the determined operating voltage; c. Determine the hydrogen concentration of the remaining fuel gas to be discharged; d. According to the hydrogen concentration determined in step c, determine whether the remaining fuel gas has reached a dischargeable level; e1. If the determination in step d is no, then close the return valve to retain the remaining fuel gas in the stack module; or open the return valve to introduce the remaining fuel gas into the cathode inlet end In the process, either the residual fuel gas is introduced into a catalytic converter, or the residual fuel gas is led back to the anode inlet end of the stack module. The fuel cell system according to claim 1, wherein the control unit executes the following steps after step d: e2. If the determination in step d is yes, discharge the remaining fuel gas through the fuel exhaust assembly. The fuel cell system according to claim 1, wherein the fuel exhaust assembly includes a discharge valve, and the discharge valve is connected to the anode exhaust end of the stack module; when the control unit executes the step d, it is determined that the If yes, open the vent valve to vent the remaining fuel gas. The fuel cell system of claim 3, wherein the return valve is connected between the anode exhaust end and the cathode intake end, and when the return valve is opened, the residual fuel gas is introduced into the return valve through the return valve in the cathode inlet. The fuel cell system according to claim 1, wherein the fuel exhaust assembly includes a discharge valve, and the discharge valve is connected to the anode exhaust end of the stack module; when the control unit executes the step d, it is determined that the If yes, open the discharge valve and close the return valve to discharge the remaining fuel gas; when the control unit executes the step d and judges it to be no, execute the step e1, close the discharge valve and open the return valve, to The remaining fuel gas is directed into the cathode inlet. The fuel cell system as claimed in claim 1, wherein the fuel exhaust assembly comprises an exhaust valve and a catalytic converter, the exhaust valve is connected to the anode exhaust end of the stack module, and the return valve is connected to between the anode exhaust end and the catalytic converter; when the control unit executes step d and determines that it is yes, opens the discharge valve and closes the return valve to discharge the remaining fuel gas; when the control unit executes When it is judged as negative in step d, step e1 is performed, the discharge valve is closed and the return valve is opened, so as to introduce the remaining fuel gas into the catalytic converter. The fuel cell system as claimed in claim 2, wherein the fuel exhaust assembly comprises a discharge valve and a return pump, the discharge valve is connected to the anode exhaust end of the stack module, and the return pump is connected to between the anode exhaust end and the anode intake end; when the control unit executes the step d, the hydrogen concentration of the remaining fuel gas is compared with a first standard value, a second standard value and a third standard value standard value, wherein the second standard value is between the first standard value and the third standard value, the third standard value is greater than the second standard value and the first standard value, if the residual fuel gas If the hydrogen concentration is less than the first standard value, it is determined as yes; if the hydrogen concentration of the remaining fuel gas is greater than the first standard value, it is determined as no: when the control unit executes the step d and determines as yes, turn on the discharge valve and close the return pump and the return valve to discharge the remaining fuel gas; when the control unit executes the step d and judges it to be no, execute the step e1; if the hydrogen concentration of the remaining fuel gas is between the When between the second standard value and the third standard value, close the discharge valve and turn on the return pump to guide the residual fuel gas back into the anode inlet; if the residual fuel gas is When the hydrogen concentration is between the first standard value and the second standard value, the discharge valve is closed and the return valve is opened to introduce the remaining fuel gas into the cathode inlet end. The fuel cell system according to claim 2, wherein the fuel exhaust assembly comprises a discharge valve, a catalytic converter and a return pump, the discharge valve is connected to the anode exhaust end of the stack module, The return valve is connected between the anode exhaust end and the catalytic converter, and the return pump is connected between the anode exhaust end and the anode intake end; when the control unit executes the step d, it is compared The hydrogen concentration of the remaining fuel gas and a first standard value, a second standard value and a third standard value, wherein the second standard value is between the first standard value and the third standard value, the The third standard value is greater than the second standard value and the first standard value, if If the hydrogen concentration of the remaining fuel gas is less than the first standard value, it is determined as yes; if the hydrogen concentration of the remaining fuel gas is greater than the first standard value, it is determined as no when the control unit executes the step d to determine If yes, open the discharge valve, close the return valve and the return pump to discharge the remaining fuel gas; when the control unit executes the step d and judges it to be no, execute the step e1; if the remaining fuel gas is When the hydrogen concentration of the fuel gas is between the second standard value and the third standard value, close the discharge valve and turn on the return pump to lead the remaining fuel gas back into the anode inlet; if all When the hydrogen concentration of the residual fuel gas is between the first standard value and the second standard value, close the discharge valve, open the return valve to introduce the residual fuel gas into the catalytic converter, or open the The return is pumped to direct the remaining fuel gas back into the anode intake. The fuel cell system according to any one of claims 1 to 8, wherein the fuel exhaust assembly includes a fuel outlet sensor connected to the anode exhaust end of the stack module, and the control unit executes the Step c is based on the sensing result of the fuel outlet sensor of the fuel exhaust assembly. The fuel cell system according to any one of claims 1 to 8, wherein the fuel intake assembly includes a feed solenoid valve, the feed solenoid valve is connected to the anode intake end, and the control unit is further based on the electrical The hydrogen concentration in the stack module is used to decide to open or close the feed solenoid valve. A control method for a fuel cell system, comprising the following steps: a. Sensing the hydrogen concentration of a supplied fuel gas; b. determining an operating voltage of a stack module of the fuel cell system according to the measured hydrogen concentration, Make the stack module operate at the determined operating voltage; c. Determine the hydrogen concentration of the remaining fuel gas to be discharged; d. According to the hydrogen concentration determined in step c, determine whether the remaining fuel gas has reached a dischargeable level; e1. If the determination in step d is no, then the remaining fuel gas is retained in the stack module or introducing the remaining fuel gas into the cathode inlet end of the stack module, or introducing the remaining fuel gas into a catalytic converter, or introducing the remaining fuel gas back to the In the anode inlet end of the stack module. The control method for a fuel cell system according to claim 11, further comprising the following steps: e2. If the determination in step d is yes, discharge the remaining fuel gas. The control method of the fuel cell system according to claim 12, wherein: in the step d, the hydrogen concentration of the remaining fuel gas is compared with a first standard value and a second standard value, wherein the first standard value is less than the second standard value, if the hydrogen concentration of the remaining fuel gas is less than the first standard value, it is determined as yes, if the hydrogen concentration of the remaining fuel gas is greater than the first standard value, it is determined as no; In this step e1, if the hydrogen concentration of the remaining fuel gas is greater than the second standard value, the remaining fuel gas is retained in the stack module; if the hydrogen concentration of the remaining fuel gas is between Between the first standard value and the second standard value, the residual fuel gas is introduced into the cathode inlet end of the stack module, or the residual fuel gas is introduced into a catalytic converter , or lead the remaining fuel gas back into the anode inlet end of the stack module. The control method of a fuel cell system according to claim 12, wherein: in the step d, the hydrogen concentration of the remaining fuel gas is compared with a first standard value, a second standard value and a third standard value , wherein the second standard value is between the first standard value and the third standard value between the standard values, the third standard value is greater than the second standard value and the first standard value, if the hydrogen concentration of the remaining fuel gas is less than the first standard value, it is determined as yes, if the remaining fuel gas If the hydrogen concentration of the remaining fuel gas is greater than the first standard value, it is determined as NO; in this step e1, if the hydrogen concentration of the remaining fuel gas is greater than the third standard value, the remaining fuel gas is retained in the stack In the module; if the hydrogen concentration of the remaining fuel gas is between the second standard value and the third standard value, the remaining fuel gas is led back to the anode intake end of the stack module ; If the hydrogen concentration of the remaining fuel gas is between the first standard value and the second standard value, the remaining fuel gas is introduced into the cathode inlet end of the stack module, or the The residual fuel gas is directed to a catalytic converter. The control method for a fuel cell system according to any one of claims 12 to 14, wherein in the step e2, the remaining fuel gas is intermittently discharged at a specific frequency. The control method for a fuel cell system according to any one of claims 12 to 14, wherein the determination of the hydrogen concentration of the remaining fuel gas in step c is selected from any one of the following methods: c1. The hydrogen concentration of the remaining fuel gas; or c2. Estimating the amount of hydrogen consumed according to the output current of the stack module, and estimating the hydrogen concentration of the remaining fuel gas. The control method for a fuel cell system according to any one of claims 12 to 14, wherein the determination of the hydrogen concentration of the remaining fuel gas in the step c is based on the results generated by combining the following two methods: c1. Measuring The hydrogen concentration of the remaining fuel gas; and c2. Estimating the amount of hydrogen consumed according to the output current of the stack module, and estimating the hydrogen concentration of the remaining fuel gas.

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