System and method for purifying condensate water and hydrogen gas for a fuel cell stack

Abstract

The present disclosure provides a system and method for purifying condensate water and hydrogen gas of a fuel cell stack, which can allow the condensate water and hydrogen gas discharged from the fuel cell stack to be directly bypassed to the drain line of the humidifier instead of the shell side of the humidifier for purification into the atmosphere according to the operating state and operating conditions of the fuel cell stack, thereby solving the problems of reverse voltage generation when the fuel cell system is cold, overflow phenomenon in the fuel cell stack, etc., to improve the operating stability of the fuel cell stack and the operating efficiency of the fuel cell system.

Description

Technical Field

[0001] This disclosure relates to a system and method for purifying condensate and hydrogen from a fuel cell stack, and more specifically, to a system and method for purifying condensate and hydrogen from a fuel cell stack, which can directly discharge a portion of the condensate and hydrogen emitted from the fuel cell stack into the atmosphere, depending on the state and operating conditions of the fuel cell stack, thereby improving the operational stability and efficiency of the fuel cell stack. Background Technology

[0002] The fuel cell system is configured to include a fuel cell stack configured to generate electrical energy, a hydrogen supply system configured to supply fuel (hydrogen) to the fuel cell stack, an air supply system configured to supply oxygen from the air, which is necessary as an oxidant for the electrochemical reaction, to the fuel cell stack, and a heat and water management system configured to control the operating temperature of the fuel cell stack.

[0003] Typically, a fuel cell stack (hereinafter referred to as a "stack") is provided as a structure in which multiple cell units are laminated and assembled. Each cell unit includes an electrolyte membrane, an anode, a cathode, a gas diffusion layer, etc., to allow hydrogen (H2) and oxygen (O2) to react and generate electrical energy. The anode is a catalyst electrode layer located on one side of the electrolyte membrane, to which hydrogen (H2) is supplied, and the cathode is a catalyst electrode layer located on the other side of the electrolyte membrane, to which air is supplied. The gas diffusion layer is disposed outside the anode and cathode.

[0004] Therefore, when the fuel cell system is running, the hydrogen supplied to the anode of the fuel cell stack is separated into protons and electrons. The protons then move toward the cathode through the electrolyte membrane, and the electrons move toward the cathode through the external circuit. This causes oxygen molecules, hydrogen ions, and electrons to react together at the cathode to generate electricity and heat, and to produce condensate (H2O) as a reaction byproduct.

[0005] refer to Figure 1 The condensate generated by the battery stack 10 is discharged through the cathode outlet of the battery stack 10 to be collected in the dehydrator 20, and when the amount of condensate collected in the dehydrator 20 is sensed by a level sensor (not shown) to be at or above a predetermined level, the drain valve 22 installed on the outlet of the dehydrator 20 is opened for a predetermined time, so that a portion of the condensate collected in the dehydrator 20 is discharged to the shell side of the humidifier 30.

[0006] For reference, the humidifier converts dry air supplied from the air supply system into humidified air to supply the humidified air to the cathode of the battery stack, and a bundled hollow fiber membrane is disposed therein through which the dry air passes.

[0007] Therefore, the condensate discharged from the dehydrator 20 to the shell side of the humidifier 30 is used to permeate into the hollow fiber membrane arranged on the central part of the shell of the humidifier 30 to convert dry air into humidified air.

[0008] Meanwhile, the hydrogen supplied to the battery stack from the hydrogen supply system reacts with air to generate nitrogen. As nitrogen gradually accumulates in the battery stack, the hydrogen concentration in the battery stack decreases. Furthermore, when the hydrogen concentration decreases to a predetermined level or lower, the amount of reactive hydrogen used to generate electricity may decrease, resulting in a reduction in the performance of the battery stack and a decrease in the voltage of the cell.

[0009] Therefore, in order to reduce the nitrogen concentration accumulating inside the battery stack, such as Figure 1 As shown, the hydrogen purification valve 12 installed on the hydrogen purification line of the battery stack 10 opens during a predetermined period of time, allowing nitrogen and non-reactive hydrogen to be purified to the shell side of the humidifier 30, thereby maintaining the hydrogen concentration in the battery stack at a predetermined level or higher to prevent a decrease in battery stack performance.

[0010] At this time, the nitrogen and oxygen purified to the shell side of the humidifier 30 are discharged into the atmosphere through the discharge line 32 connected to the humidifier 30.

[0011] However, during cold operation of the fuel cell system, the pressure on the cathode side increases due to the freezing of condensate at the cathode outlet. This can lead to a reverse voltage problem as air supplied to the cathode flows back towards the anode.

[0012] Furthermore, if air is supplied excessively to the humidifier from the air supply system while the condensate generated by the battery stack is collected in the dehydrator and then discharged to the shell side of the humidifier, there is a problem that the condensate discharged to the shell side of the humidifier is drawn into the inlet of the battery stack cathode along with the air, resulting in an overflow phenomenon in the battery stack.

[0013] The information disclosed in this background section is intended only to enhance the understanding of the background of this disclosure and may therefore contain information that does not constitute prior art known to a person skilled in the art in this country. Summary of the Invention

[0014] This disclosure aims to solve the above-mentioned problems, and its purpose is to provide a system and method for purifying condensate and hydrogen in a fuel cell stack. Depending on the operating state and conditions of the fuel cell stack, the system and method can directly bypass the condensate and hydrogen discharged from the fuel cell stack to the discharge line of the humidifier instead of the shell side of the humidifier, so as to purify them into the atmosphere. This eliminates problems such as the generation of reverse voltage and overflow in the fuel cell stack during cold operation of the fuel cell system, thereby improving the operating stability of the fuel cell stack and the operating efficiency of the fuel cell system.

[0015] An exemplary embodiment of this disclosure for achieving this purpose provides a system for purifying condensate and hydrogen from a fuel cell stack, comprising: an integrated purge valve, wherein a hydrogen purge line for the fuel cell stack and an outlet line for a dehydrator that collects condensate generated by the fuel cell stack are commonly connected to the integrated purge valve; a three-way purge bypass valve mounted at the outlet of the integrated purge valve; a discharge line connected between a first outlet of the three-way purge bypass valve and the shell side of a humidifier; and a bypass line connected between a second outlet of the three-way purge bypass valve and the discharge line of the humidifier.

[0016] According to an exemplary embodiment of this disclosure, when the pressure at the cathode of the fuel cell stack increases to or above a predetermined level during cold start and cold operation of the fuel cell system, the integrated purge valve opens, and simultaneously, the three-way purge bypass valve opens toward the bypass line connected to the discharge line of the humidifier.

[0017] On the other hand, when the pressure at the cathode of the battery stack is at a normal level below the predetermined level, the integrated purge valve opens, and at the same time, the three-way purge bypass valve opens toward the discharge line connected to the shell side of the humidifier.

[0018] According to an exemplary embodiment of this disclosure, when it is determined that the relative humidity inside the battery stack exceeds a reference value, the hydrogen concentration on the anode side inside the battery stack is equal to or lower than a reference value, or a battery overflow occurs, the integrated purification valve is opened, and at the same time, the three-way purification bypass valve opens toward the bypass line connected to the discharge line of the humidifier.

[0019] On the other hand, when it is determined that the relative humidity inside the battery stack meets the reference value, the hydrogen concentration on the anode side of the battery stack meets the reference value, and no battery overflow occurs inside the battery stack, the integrated purification valve is opened, and at the same time, the three-way purification bypass valve is opened toward the discharge line connected to the shell side of the humidifier.

[0020] Another exemplary embodiment of this disclosure for achieving this purpose provides a method for purifying condensate and hydrogen in a fuel cell stack, comprising: determining whether to perform a cold start and cold run of the fuel cell system; when the fuel cell system is in a cold start and cold run state, determining whether the pressure at the cathode of the stack increases; when it is determined that the pressure at the cathode of the stack increases to or above a predetermined level, discharging condensate and non-reactive residual hydrogen discharged from the cathode of the stack into the atmosphere through the discharge line of a humidifier; and when the pressure at the cathode of the stack is at a normal level below the predetermined level, discharging condensate and non-reactive residual hydrogen discharged from the cathode of the stack to the shell side of the humidifier.

[0021] When condensate and non-reactive residual hydrogen are discharged into the atmosphere through the humidifier's discharge line, the integrated purification valve, which is connected to both the hydrogen purification line of the battery stack and the outlet line of the dehydrator, is opened. At the same time, the three-way purification bypass valve installed at the outlet of the integrated purification valve opens toward the humidifier's discharge line.

[0022] When condensate and non-reactive residual hydrogen are discharged to the shell side of the humidifier, the integrated purification valve, which is connected to both the hydrogen purification line of the battery stack and the outlet line of the dehydrator, is opened. At the same time, the three-way purification bypass valve installed on the outlet of the integrated purification valve is opened toward the shell side of the humidifier.

[0023] Another exemplary embodiment of this disclosure further includes determining whether the relative humidity in the fuel cell stack meets a reference value, whether the hydrogen concentration in the fuel cell stack meets a reference value, or whether battery overflow occurs in the multiple cells of the fuel cell stack due to condensation when it is determined that the fuel cell system is in a normal start-up and normal operation state rather than a cold start-up and cold operation state.

[0024] Therefore, when it is determined that the relative humidity inside the battery stack exceeds the reference value, the hydrogen concentration on the anode side of the battery stack is at or below the reference value, or a battery overflow occurs inside the battery stack, the integrated purification valve is opened, and at the same time, the three-way purification bypass valve opens toward the humidifier's discharge line.

[0025] On the other hand, when it is determined that the relative humidity inside the battery stack meets the reference value, the hydrogen concentration on the anode side of the battery stack meets the reference value, and no battery overflow occurs inside the battery stack, the integrated purification valve is opened, and at the same time, the three-way purification bypass valve is opened toward the discharge line connected to the shell side of the humidifier.

[0026] This disclosure provides the following effects through the above configuration.

[0027] First, during cold start and cold operation of the fuel cell system, the reverse voltage phenomenon caused by air flowing back from the cathode side to the anode when hydrogen is purified can be prevented by increasing the cathode pressure as the condensate at the cathode outlet of the fuel cell stack freezes.

[0028] Secondly, by allowing nitrogen and residual hydrogen accumulated in the battery stack to be directly purified into the atmosphere without passing through the humidifier, large amounts of nitrogen and residual hydrogen can be purified immediately, thereby preventing the reduction in the durability and lifespan of related valve series, etc., due to the traditional frequent hydrogen purification.

[0029] Third, it allows the condensate from the battery stack to be directly purified into the atmosphere using the pressure difference with the atmosphere, instead of being discharged to the shell side of the humidifier. This prevents the conventional overflow phenomenon caused by the condensate discharged to the shell side of the humidifier being drawn into the cathode inlet of the battery stack along with the air, thus preventing shell overflow.

[0030] Fourth, when the relative humidity (RH) inside the battery stack exceeds the reference value, or when the hydrogen concentration on the anode side of the battery stack is at or below the reference value, the residual hydrogen, including condensate and nitrogen, is purified into the atmosphere through a three-way purification bypass valve and bypass pipeline. This allows the relative humidity and hydrogen concentration of the battery stack to be adjusted to appropriate levels according to the operating conditions and status of the battery stack, thereby improving the durability of the battery stack.

[0031] It should be understood that the terms "automotive" or "vehicular" or other similar terms used herein include motor vehicles in general, such as passenger cars including SUVs, buses, trucks, various commercial vehicles, water vehicles including various boats and vessels, aircraft, etc., and include hybrid electric vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other vehicles powered by alternative fuels (e.g., fuels derived from resources other than petroleum). As described herein, a hybrid electric vehicle is a vehicle with two or more power sources, such as a gasoline-powered and an electric vehicle. Attached Figure Description

[0032] The above and other features of this disclosure will now be described in detail with reference to certain exemplary examples shown in the accompanying drawings, which are given hereinafter by way of illustration only and are not intended to limit the disclosure, and wherein:

[0033] Figure 1 This is a schematic diagram illustrating a conventional system for purifying condensate and hydrogen in a fuel cell stack.

[0034] Figure 2This is a schematic diagram illustrating a system for purifying condensate and hydrogen in a fuel cell stack according to the present disclosure;

[0035] Figure 3 This is a flowchart illustrating the operation of a system for purifying condensate and hydrogen in a fuel cell stack according to the present disclosure.

[0036] It should be understood that the accompanying drawings are not necessarily to scale and present slightly simplified representations of various preferred features illustrating the basic principles of this disclosure. Specific design features of this disclosure will be partially determined by the particular intended application and usage environment, including, for example, specific dimensions, orientations, positions, and shapes.

[0037] In the accompanying drawings, reference numerals throughout the drawings refer to the same or equivalent parts of this disclosure. Detailed Implementation

[0038] Preferred exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0039] Figure 2 This is a diagram showing the configuration of a system for purifying condensate and hydrogen in a fuel cell stack according to the present disclosure, and reference numeral 10 denotes the fuel cell stack.

[0040] The hydrogen purification line 11, which is connected to the outlet of the anode of the battery stack 10, is equipped with an integrated purification valve 40.

[0041] In addition, the outlet line of the dehydrator 20, which collects the condensate generated by the battery stack 10, is connected to the inlet of the integrated purge valve 40.

[0042] The integrated purification valve 40 is a valve in which a hydrogen purification valve installed on a conventional hydrogen purification line and a drain valve installed at the outlet of the dehydrator are integrated into one unit, and is used to discharge condensate collected in the dehydrator 20, as well as nitrogen and non-reactive residual hydrogen discharged through the outlet of the anode of the battery stack 10, toward the three-way purification bypass valve 50 by opening and closing operations.

[0043] Therefore, the condensate generated by the battery stack 10 is discharged through the outlet of the cathode of the battery stack 10 and collected in the dehydrator 20. Then, when the amount of condensate collected in the dehydrator 20 is sensed by a level sensor (not shown) to be at or above a predetermined level, the integrated purifying valve 40 opens for a predetermined time period, so that the condensate can be discharged to the shell side of the humidifier 30.

[0044] In addition, in order to reduce the nitrogen concentration accumulated in the battery stack 10, nitrogen and non-reactive hydrogen can be purified from the battery stack 10 to the shell side of the humidifier 30 when the integrated purification valve 40 is opened for a predetermined period of time.

[0045] According to this disclosure, a three-way purification bypass valve 50 is installed at the outlet of the integrated purification valve 40.

[0046] Specifically, the discharge line 53 is connected between the first outlet 51 of the three-way purification bypass valve 50 and the shell side of the humidifier 30, and the bypass line 54 is connected between the second outlet 52 of the three-way purification bypass valve 50 and the discharge line 32 of the humidifier 30.

[0047] Therefore, depending on the operating status and conditions of the battery stack 10, the condensate and hydrogen discharged from the battery stack 10 can be directly bypassed to the discharge line 32 of the humidifier 30 through the bypass line 54 connected to the second outlet 52 of the three-way purification bypass valve 50, so as to be purified into the atmosphere and not discharged to the shell side of the humidifier 30.

[0048] Meanwhile, a pressure regulating valve 31 is installed on the inlet side of the discharge pipe 32 of the humidifier 30. This pressure regulating valve regulates the air pressure inside the humidifier and prevents the infiltration of external air.

[0049] The following will be used as a reference here. Figure 2 and Figure 3 Describe the process of purifying condensate and hydrogen from a fuel cell stack based on the above configuration.

[0050] First, determine at S101 whether to perform cold start and cold run of the fuel cell system, including the battery stack.

[0051] For example, when the outside air temperature is 2°C or lower, it can be determined that the fuel cell system is in a cold start and cold operation state.

[0052] When the fuel cell system is in a cold start and cold operation state, determine at S102 whether the pressure of the cathode of the fuel cell stack increases.

[0053] For example, when the cathode and anode pressures of the battery stack remain at the same level for a predetermined time or longer (e.g., 5 seconds), the pressure difference between the cathode and anode increases to a reference value or greater, making it possible to determine that the cathode pressure has increased to a predetermined level or greater.

[0054] At this point, the reason for the increase in pressure at the cathode of the fuel cell stack is that, during cold operation of the fuel cell system, some of the condensate freezes at the outlet of the cathode of the fuel cell stack, and when the pressure at the cathode of the fuel cell stack increases as described above, a problem arises in which reverse voltage is generated by the air supplied to the cathode flowing back towards the anode.

[0055] To address this issue, at S103, when it is determined that the pressure at the cathode of the battery stack 10 has increased to a predetermined level or higher, the integrated purge valve 40 opens via a control signal from the controller. Simultaneously, the three-way purge bypass valve 50 opens toward the second outlet 52, and the bypass line 54 is connected to the second outlet 52.

[0056] Therefore, the outlet of the cathode of the battery stack 10 is connected to the discharge line 32 of the humidifier 30, which is connected to the atmosphere via the bypass line 54.

[0057] At this time, the first outlet 51 of the three-way purification bypass valve 50 remains closed.

[0058] Therefore, atmospheric purification is performed at S104, in which condensate from the cathode of the battery stack, non-reactive residual hydrogen, etc. are directly discharged into the atmosphere through the discharge line 32 of the humidifier 30, the three-way purification bypass valve 50, and the bypass line 54.

[0059] As described above, under cold start and cold operation conditions of a fuel cell system including a battery stack, by allowing the condensate and hydrogen discharged from the battery stack 10 to be directly bypassed through the bypass line 54 connected to the second outlet 52 of the three-way purge bypass valve 50 to the discharge line 32 of the humidifier 30 without discharging the condensate and hydrogen to the shell side of the humidifier, thereby purifying them into the atmosphere, the pressure at the cathode of the battery stack can be reduced, and the phenomenon of reverse voltage being generated by the air supplied to the cathode of the battery stack flowing back towards the anode can be prevented.

[0060] On the other hand, as a result of step S102, when it is determined that the pressure of the cathode of the battery stack has not increased to a predetermined level or higher, that is, when the pressure of the cathode of the battery stack is at a normal level lower than the predetermined level, if drainage and hydrogen purification are required, the integrated purification valve 40 is opened by the control signal of the controller, and at the same time, the three-way purification bypass valve 50 is opened toward the first outlet 51.

[0061] At this time, the three-way purification bypass valve 50 remains closed on the second outlet 52 side.

[0062] Therefore, at S105, the condensate and residual hydrogen discharged from the battery stack 10 are purified along the first outlet 51 of the three-way purification bypass valve 50 and the discharge line 53 toward the shell side of the humidifier 30, and the discharged condensate is used to convert dry air into humidified air in the humidifier, and the discharged residual hydrogen is discharged into the atmosphere through the discharge line 32 of the humidifier 30.

[0063] Meanwhile, as a result of step S101, when the fuel cell system including the battery stack is not in a cold start or cold operation state, that is, when it is determined that the fuel cell system is in a normal start and normal operation state, at step S106, it is determined whether the relative humidity (RH) in the battery stack meets the reference value, whether the hydrogen concentration in the battery stack meets the reference value, and whether the condensate in the multiple cells of the battery stack causes battery overflow, etc.

[0064] In other words, it determines whether the relative humidity (RH) inside the battery stack exceeds the reference value, whether the hydrogen concentration on the anode side of the battery stack is at or below the reference value, and whether battery overflow has occurred.

[0065] For battery overflow, a battery overflow is determined to occur when the differential voltage (DV) between multiple batteries is 40mV or higher.

[0066] Therefore, at S107, when it is determined that the relative humidity (RH) inside the battery stack exceeds the reference value (based on the target RH diagram), the hydrogen concentration on the anode side inside the battery stack is determined to be at or below the reference value, or a battery overflow is determined to occur, the integrated purge valve 40 is opened by the control signal of the controller, and at the same time, the three-way purge bypass valve 50 is opened toward the second outlet 52 connected to the bypass line 54.

[0067] Subsequently, atmospheric purification is performed at S108, in which condensate from the battery stack and residual hydrogen including nitrogen are discharged directly into the atmosphere through the discharge line 32 of the humidifier 30, the three-way purification bypass valve 50, and the bypass line 54.

[0068] Therefore, when the relative humidity (RH) inside the battery stack is determined to exceed the reference value (based on the target RH map), condensate from the battery stack can be allowed to be directly purified into the atmosphere through the humidifier's discharge line without discharging the condensate to the humidifier's shell side, thereby adjusting the relative humidity (RH) inside the battery stack to a level that meets the reference value.

[0069] In addition, when a battery overflow is detected, condensate from the battery stack can be allowed to be directly purified into the atmosphere through the humidifier's discharge line instead of being discharged to the humidifier's shell side. This prevents the conventional overflow phenomenon caused by condensate discharged to the humidifier's shell side being drawn into the battery stack cathode inlet along with the air.

[0070] Meanwhile, the hydrogen supplied to the battery stack reacts with air to generate nitrogen. As nitrogen gradually accumulates in the battery stack, the hydrogen concentration in the battery stack decreases. When the hydrogen concentration decreases to a predetermined level or lower, the amount of hydrogen used for generating electricity may decrease, resulting in a reduction in the performance of the battery stack and a decrease in the voltage of the cell.

[0071] Therefore, when the hydrogen concentration on the anode side of the battery stack is determined to be at or below a reference value, allowing the non-reactive residual hydrogen, including nitrogen as described above, to be directly purified into the atmosphere through the humidifier's exhaust line, instead of being discharged from the battery stack to the humidifier's shell side, avoids purification pressure resistance compared to venting the non-reactive residual hydrogen into the atmosphere through the humidifier's shell side. Thus, the non-reactive residual hydrogen, including nitrogen, can be purified into the atmosphere more quickly, thereby reducing the nitrogen concentration within the battery stack to adjust the hydrogen concentration supplied to the battery stack to the reference value or higher, and preventing a degradation in battery stack performance.

[0072] On the other hand, as a result of step S106, when it is determined that the relative humidity (RH) inside the battery stack does not exceed the reference value (based on the target RH diagram), it is uncertain whether the hydrogen concentration on the anode side inside the battery stack is the reference value or lower, and it is determined that no battery overflow has occurred, if drainage and hydrogen purification are required, the integrated purification valve 40 is opened by the control signal of the controller, and at the same time, the three-way purification bypass valve 50 is opened toward the first outlet 51.

[0073] That is, when it is determined that the relative humidity inside the battery stack meets the reference value, the hydrogen concentration on the anode side of the battery stack meets the reference value, and no battery overflow occurs inside the battery stack, the integrated purification valve 40 is opened, and at the same time, the three-way purification bypass valve 50 is opened toward the discharge line 53 connected to the shell side of the humidifier 30.

[0074] Therefore, at S109, the condensate and residual hydrogen discharged from the battery stack 10 are purified along the first outlet 51 of the three-way purification bypass valve 50 and the discharge line 53 toward the shell side of the humidifier 30, and the discharged condensate is used to convert dry air into humidified air in the humidifier, and the discharged residual hydrogen is discharged into the atmosphere through the discharge line 32 of the humidifier 30.

[0075] While several exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize that further modifications, substitutions, additions, and sub-combinations of the features of the disclosed embodiments are still possible.

Claims

1. A system for purifying condensate and hydrogen in a fuel cell stack, comprising: An integrated purge valve with an outlet is connected to the hydrogen purification line of the fuel cell stack and the outlet line of a dehydrator that collects condensate generated by the fuel cell stack. A three-way purification bypass valve is installed at the outlet of the integrated purification valve; The discharge pipeline is connected between the first outlet of the three-way purification bypass valve and the shell side of the humidifier; as well as A bypass line is provided, which connects the second outlet of the three-way purification bypass valve to the discharge line of the humidifier.

2. The system for purifying condensate and hydrogen in a fuel cell stack according to claim 1. in, When the pressure at the cathode of the fuel cell stack increases to or exceeds a predetermined level during cold start and cold operation of the fuel cell system, the integrated purge valve opens, and simultaneously, the three-way purge bypass valve opens toward the bypass line connected to the discharge line of the humidifier.

3. The system for purifying condensate and hydrogen in a fuel cell stack according to claim 2. in, When the pressure at the cathode of the fuel cell stack is at a normal level below the predetermined level, the integrated purge valve opens, and simultaneously, the three-way purge bypass valve opens toward the discharge line connected to the shell side of the humidifier.

4. The system for purifying condensate and hydrogen in a fuel cell stack according to claim 1, in, When it is determined that the relative humidity inside the fuel cell stack exceeds the reference value, or when it is determined that the hydrogen concentration on the anode side of the fuel cell stack is equal to or lower than the reference value, or when it is determined that a battery overflow has occurred, the integrated purification valve opens, and at the same time, the three-way purification bypass valve opens toward the bypass line connected to the discharge line of the humidifier.

5. The system for purifying condensate and hydrogen in a fuel cell stack according to claim 1, in, When it is determined that the relative humidity in the fuel cell stack meets the reference value, the hydrogen concentration on the anode side of the fuel cell stack meets the reference value, and no battery overflow occurs in the fuel cell stack, the integrated purification valve opens, and at the same time, the three-way purification bypass valve opens toward the discharge line connected to the shell side of the humidifier.

6. A method for purifying condensate and hydrogen in a fuel cell stack, the method comprising: Determine whether to perform a cold start and cold run of the fuel cell system; When the fuel cell system is in the cold start and cold operation state, determine whether the pressure at the cathode of the fuel cell stack increases; When it is determined that the pressure at the cathode of the fuel cell stack increases to or above a predetermined level, the condensate and non-reactive residual hydrogen emitted from the cathode of the fuel cell stack will be discharged into the atmosphere through the humidifier's discharge line. as well as When it is determined that the pressure at the cathode of the fuel cell stack is at a normal level below the predetermined level, the integrated purge valve of the hydrogen purification line and the outlet line of the dehydrator connected to the fuel cell stack is opened, and the condensate and non-reactive residual hydrogen discharged from the cathode of the fuel cell stack are discharged into the atmosphere through the bypass line connected to the discharge line of the humidifier.

7. The method according to claim 6, in, When condensate and non-reactive residual hydrogen are discharged into the atmosphere through the humidifier's discharge line... Open the integrated purification valve that connects the hydrogen purification pipeline of the battery stack and the outlet pipeline of the dehydrator. At the same time, open the three-way purification bypass valve installed on the outlet of the integrated purification valve toward the discharge pipeline of the humidifier.

8. The method according to claim 6, in, When condensate and non-reactive residual hydrogen are discharged to the shell side of the humidifier Open the integrated purification valve that connects the hydrogen purification pipeline of the battery stack and the outlet pipeline of the dehydrator. At the same time, open the three-way purification bypass valve installed on the outlet of the integrated purification valve toward the shell side of the humidifier.

9. The method according to claim 6, in, When it is determined that the fuel cell system is in a normal start-up and normal operation state rather than a cold start-up and cold operation state, the determination is performed on whether the relative humidity in the fuel cell stack meets the reference value, whether the hydrogen concentration in the fuel cell stack meets the reference value, or whether battery overflow occurs in the multiple cells configured with the fuel cell stack due to the condensate.

10. The method according to claim 7, in, When it is determined that the relative humidity inside the fuel cell stack exceeds the reference value, the hydrogen concentration on the anode side of the fuel cell stack is determined to be at or below the reference value, or a battery overflow occurs inside the fuel cell stack, the integrated purification valve is opened, and at the same time, the three-way purification bypass valve is opened towards the discharge line of the humidifier.

11. The method according to claim 10, in, When the relative humidity inside the fuel cell stack is determined to exceed the reference value, the condensate from the fuel cell stack is purified into the atmosphere through the humidifier's discharge line.

12. The method according to claim 10, in, When the battery overflow is detected, the condensate is purified from the fuel cell stack into the atmosphere through the humidifier's discharge line.

13. The method according to claim 10, in, When the hydrogen concentration on the anode side of the fuel cell stack is determined to be at or below the reference value, the non-reactive residual hydrogen containing nitrogen is purified from the fuel cell stack into the atmosphere through the humidifier's discharge line.

14. The method according to claim 7, in, When it is determined that the relative humidity in the fuel cell stack meets the reference value, the hydrogen concentration on the anode side of the fuel cell stack meets the reference value, and no battery overflow occurs in the fuel cell stack, the integrated purification valve is opened, and at the same time, the three-way purification bypass valve is opened toward the discharge line connected to the shell side of the humidifier.

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