Fuel cell system

Abstract

The present invention provides a fuel cell system that can prevent the fuel cell system from being started while condensation is present, and can also prevent condensation from occurring during startup. [Solution] The fuel cell system includes an anode exhaust gas temperature sensor 32 for measuring the temperature of the anode exhaust gas and a cathode exhaust gas temperature sensor 33 for measuring the temperature of the cathode exhaust gas. The operation control unit 13 performs a pretreatment in which the water supply unit 27 does not supply water to the reforming unit 9, supplies the raw fuel gas to the reforming unit 9 while heating the raw fuel gas using the raw fuel gas heating unit 28, and supplies the oxidizer gas to the cathode 6 while heating the oxidizer gas using the oxidizer gas heating unit 30. When the necessary temperature conditions are met, including at least the temperature of the anode exhaust gas being at or above a first set temperature and the temperature of the cathode exhaust gas being at or above a second set temperature, the pretreatment is terminated and the water supply unit 27 starts a startup process in which it supplies water to the reforming unit 9.

Description

Technical Field

[0001] The present invention relates to a fuel cell system.

Background Art

[0002] In Patent Document 1 (Japanese Patent Application Laid-Open No. 2023-166294), it is an object to suppress the occurrence of condensation during the startup of a fuel cell. For example, by raising the temperature of the oxidant gas supplied to the air electrode side of the fuel cell with a heat exchanger (air preheater 30), it is attempted to prevent the occurrence of condensation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a fuel cell, a raw fuel gas containing hydrocarbons is steam reformed, and a fuel gas containing hydrogen generated by the steam reforming is supplied to the anode. Also, at the cathode, hydrogen ions and oxygen ions react to generate water. Thus, during the power generation of the fuel cell, water or water vapor exists in the anode and the cathode. And when the power generation operation of the fuel cell is stopped and its temperature decreases, the moisture remaining inside the fuel cell including the anode and the cathode will condense.

[0005] If the operation of the fuel cell is restarted and its temperature begins to rise while water is condensed inside the fuel cell, it is difficult for the temperature to rise due to the latent heat of water in the condensed part, and the temperature rise progresses in the non-condensed part. Therefore, there is a risk that the temperature difference inside the fuel cell will widen. And there is a possibility that it will lead to a failure of the fuel cell due to thermal stress.

[0006] The present invention has been made in view of the above problems, and its objective is to provide a fuel cell system that can prevent the fuel cell system from being started while condensation is present, and can also prevent condensation from occurring during startup. [Means for solving the problem]

[0007] A characteristic configuration of the fuel cell system according to the present invention for achieving the above objective is a fuel cell system comprising: a raw fuel gas supply unit that supplies raw fuel gas containing hydrocarbons; a reforming unit that steam reforms the raw fuel gas to produce fuel gas containing hydrogen; a water supply unit that supplies water used for the steam reforming; a fuel cell unit comprising a fuel cell cell having an anode to which the fuel gas produced in the reforming unit is supplied, a cathode to which an oxidant gas is supplied, and an electrolyte provided between the anode and the cathode; an oxidant gas supply unit that supplies the oxidant gas to the cathode; a combustion unit to which anode exhaust gas discharged from the anode and cathode exhaust gas discharged from the cathode are supplied, enabling combustion of combustible components contained in the anode exhaust gas; and an operation control unit, wherein the combustion heat generated in the combustion unit is transmitted to the reformer. A raw fuel gas heating unit capable of heating the raw fuel gas supplied to the reforming unit, An oxidizing agent gas heating unit capable of heating the oxidizing agent gas supplied to the cathode, An anode exhaust gas temperature sensor that measures the temperature of the anode exhaust gas, The system includes a cathode exhaust gas temperature sensor for measuring the temperature of the cathode exhaust gas, The aforementioned operation control unit, The key point is that, while the water supply unit does not supply water to the reforming unit, and the raw fuel gas supplied by the raw fuel gas supply unit is supplied to the reforming unit while being heated using the raw fuel gas heating unit, and the oxidizer gas supplied by the oxidizer gas supply unit is supplied to the cathode while being heated using the oxidizer gas heating unit, the pretreatment is terminated and the start-up process in which the water supply unit supplies water to the reforming unit is initiated when the necessary temperature conditions are met, including at least the temperature of the anode exhaust gas being at or above a first set temperature and the temperature of the cathode exhaust gas being at or above a second set temperature.

[0008] According to the above characteristic configuration, before the start-up process in which the water supply unit supplies water to the reforming unit, a pre-treatment is performed in which the water supply unit does not supply water to the reforming unit, and the raw fuel gas supplied by the raw fuel gas supply unit is heated using the raw fuel gas heating unit while the raw fuel gas is supplied to the reforming unit, and the oxidizer gas supplied by the oxidizer gas supply unit is heated using the oxidizer gas heating unit while the oxidizer gas is supplied to the cathode. This pre-treatment is performed until the necessary temperature conditions are met, including at least the temperature of the anode exhaust gas being at or above the first set temperature and the temperature of the cathode exhaust gas being at or above the second set temperature. In other words, since heated raw fuel gas that does not contain moisture flows through the gas flow paths on the anode and its upstream and downstream sides, any moisture remaining there will be removed by the flow of raw fuel gas at or above the first set temperature (i.e., high temperature). Also, since oxidizer gas that does not contain moisture flows through the gas flow paths on the cathode and its upstream and downstream sides, any moisture remaining there will be removed by the flow of oxidizer gas at or above the second set temperature (i.e., high temperature). Then, after the gas flow paths of the anode and its upstream and downstream sides, as well as the gas flow paths of the cathode and its upstream and downstream sides, have reached a high temperature (i.e., a state where water condensation does not occur), the start-up process begins in which the water supply unit supplies water to the reforming unit. Therefore, it is possible to provide a fuel cell system that can prevent the fuel cell system from being started while condensation is present, and that can prevent condensation from occurring during startup.

[0009] Another characteristic configuration of the fuel cell system according to the present invention is a fuel gas temperature sensor capable of measuring the temperature of the fuel gas after it has been heated in the fuel gas heating section, The system includes an oxidant gas temperature sensor capable of measuring the temperature of the oxidant gas after it has been heated in the oxidant gas heating section, The aforementioned operation control unit, The key point is that the required temperature conditions are determined to be met when the temperature of the anode exhaust gas is equal to or above a first set temperature, the temperature of the cathode exhaust gas is equal to or above a second set temperature, the temperature difference between the temperature of the raw fuel gas measured by the raw fuel gas temperature sensor and the temperature of the anode exhaust gas measured by the anode exhaust gas temperature sensor is within a predetermined first temperature difference, and the temperature difference between the temperature of the oxidizer gas measured by the oxidizer gas temperature sensor and the temperature of the cathode exhaust gas measured by the cathode exhaust gas temperature sensor is within a predetermined second temperature difference.

[0010] If there is no moisture in the gas flow path of the anode and its upstream and downstream sides, and the area becomes hot, the temperature difference between the temperature of the raw fuel gas measured by the raw fuel gas temperature sensor and the temperature of the anode exhaust gas measured by the anode exhaust gas temperature sensor will decrease. Similarly, if there is no water in the gas flow path of the cathode and its upstream and downstream sides, and the area becomes hot, the temperature difference between the temperature of the oxidizer gas measured by the oxidizer gas temperature sensor and the temperature of the cathode exhaust gas measured by the cathode exhaust gas temperature sensor will decrease. Therefore, in this feature configuration, the operation control unit can determine that the necessary temperature conditions are met when the temperature of the anode exhaust gas is above the first set temperature, the temperature of the cathode exhaust gas is above the second set temperature, the temperature difference between the temperature of the raw fuel gas measured by the raw fuel gas temperature sensor and the temperature of the anode exhaust gas measured by the anode exhaust gas temperature sensor is within a predetermined first temperature difference, and the temperature difference between the temperature of the oxidizer gas measured by the oxidizer gas temperature sensor and the temperature of the cathode exhaust gas measured by the cathode exhaust gas temperature sensor is within a predetermined second temperature difference.

[0011] Another characteristic feature of the fuel cell system according to the present invention is that the raw fuel gas heating section and the oxidizer gas heating section are configured using electric heaters.

[0012] According to the above-described configuration, the raw fuel gas and oxidizer gas can be heated using an electric heater.

[0013] Another characteristic feature of the fuel cell system according to the present invention is that the first set temperature and the second set temperature are temperatures of 100°C or higher.

[0014] According to the above-described configuration, the pretreatment is performed such that the temperature of the anode exhaust gas reaches at least 100°C and the temperature of the cathode exhaust gas reaches at least 100°C, thereby ensuring the removal of moisture from the anode and the gas flow paths upstream and downstream of it, as well as from the cathode and the gas flow paths upstream and downstream of it. [Brief explanation of the drawing]

[0015] [Figure 1] This is a diagram showing the configuration of a fuel cell system. [Figure 2] This is a flowchart explaining the startup process. [Modes for carrying out the invention]

[0016] A fuel cell system according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a diagram illustrating the configuration of the fuel cell system.

[0017] The fuel cell system has a container 1, and inside the container 1, there are provided a plurality of fuel cell units 3 having an anode 4 and a cathode 6, a vaporization unit 8 that generates water vapor, a reforming unit 9 that steam-reforms a raw fuel gas containing hydrocarbons such as city gas to produce a fuel gas containing hydrogen, a fuel gas supply passage 16 that supplies the fuel gas from the reforming unit 9 to the anode 4, a combustion unit 10 that burns the exhaust gas discharged from the fuel cell unit 7, and a combustion exhaust gas passage 22 that guides the combustion exhaust gas generated in the combustion unit 10 to the outside of the container 1. This container 1 and each device housed in the container 1 may also be referred to as a hot module 2.

[0018] In the middle of the combustion exhaust gas passage 22, there is provided a heat exchange unit 11 to which the combustion exhaust gas discharged from the combustion unit 10 is supplied. And in the heat exchange unit 11, the heat of the combustion exhaust gas is transferred to the vaporization unit 8 and the reforming unit 9.

[0019] Also, the fuel cell system includes a raw fuel gas supply unit 23 that supplies a raw fuel gas containing hydrocarbons from the outside of the container 1 to the reforming unit 9, an oxidant gas supply unit 24 that supplies air from the outside of the container 1 to the fuel cell unit 7, a water supply unit 27 that supplies water (hereinafter sometimes referred to as reforming water) used for steam reforming from the outside of the container 1, and an operation control unit 13. The fuel cell system also includes a storage unit 14 that stores information.

[0020] The reforming water is supplied to the reforming unit 9 via a water supply passage 20. In the present embodiment, since the vaporization unit 8 is provided upstream of the reforming unit 9, the reforming water is first supplied to the vaporization unit 8 and then supplied to the reforming unit 9. The water supply passage 20 is provided with a water supply unit 27 that supplies the reforming water, which is realized by using a pump, a flow meter, etc. The water supply unit 27 can adjust the flow rate of the reforming water supplied to the vaporization unit 8 and the reforming unit 9 per unit time. And in the vaporization unit 8, the combustion heat generated in the combustion unit 10 described later is transferred to vaporize the reforming water supplied from the water supply unit 27. The operation of the water supply unit 27 is controlled by the operation control unit 13.

[0021] Furthermore, the vaporization section 8 is supplied with raw fuel gas containing hydrocarbons via the raw fuel gas supply passage 15. In other words, the reforming section 9, located downstream of the vaporization section 8, is supplied with raw fuel gas containing hydrocarbons via the raw fuel gas supply passage 15. The raw fuel gas supply passage 15 is provided with a raw fuel gas supply section 23, which supplies the raw fuel gas using a blower, flow meter, etc. The raw fuel gas supply section 23 can adjust the flow rate of raw fuel gas per unit time supplied to the reforming section 9. In this embodiment, since the vaporization section 8 is located upstream of the reforming section 9, the water vapor generated in the vaporization section 8 and the supplied raw fuel gas are mixed in the vaporization section 8. The operation of the raw fuel gas supply unit 23 is controlled by the operation control unit 13.

[0022] In the reforming unit 9, heat from the combustion exhaust gas is transferred by the heat exchange unit 11. Then, in the reforming unit 9, the raw fuel gas supplied from the raw fuel gas supply unit 23 is steam reformed to produce a fuel gas containing hydrogen. The fuel gas produced in the reforming unit 9 flows to the fuel cell unit 7 via the fuel gas supply passage 16. In addition, if the reforming process of the raw fuel gas is not sufficiently performed in the reforming unit 9, such as during startup, the raw fuel gas is also supplied from the reforming unit 9 to the fuel cell unit 7 via the fuel gas supply passage 16.

[0023] The fuel cell unit 7 comprises a fuel cell cell 3 having an anode 4 to which the fuel gas produced in the reforming unit 9 is supplied, a cathode 6 to which an oxidizing gas is supplied, and an electrolyte 5 provided between the anode 4 and the cathode 6. For example, the fuel cell cell 3 is a solid oxide type fuel cell cell using a solid electrolyte.

[0024] The fuel cell system includes a fuel gas supply passage 16 through which the fuel gas generated in the reforming unit 9 flows toward the anode 4 of the fuel cell unit 7, and an oxidizer gas supply passage 17 through which air supplied to the fuel cell unit 7 flows. If fuel gas is not generated in the reforming unit 9, raw fuel gas flows through the fuel gas supply passage 16, and as a result, raw fuel gas is supplied to the anode 4.

[0025] Each fuel cell cell 3 generates electricity using the fuel gas produced in the reforming unit 9 and air (oxygen) supplied as an oxidizer gas from the oxidizer gas supply unit 24. Specifically, the anode 4 is supplied with fuel gas via the fuel gas supply passage 16, and the cathode 6 is supplied with air (oxygen) via the oxidizer gas supply passage 17. In addition, if the raw fuel gas is not sufficiently reformed in the reforming unit 9, such as during startup, the raw fuel gas is also supplied from the reforming unit 9 to the anode 4. The oxidizer gas supply passage 17 is equipped with an oxidizer gas supply unit 24, which supplies air as an oxidizer gas, and is implemented using a pump, flow meter, etc. The oxidizer gas supply unit 24 can adjust the flow rate of air per unit time supplied to the fuel cell unit 7. The operation of the oxidizer gas supply unit 24 is controlled by the operation control unit 13.

[0026] Furthermore, not all of the fuel gas supplied to the anode 4, such as hydrogen, is used for power generation; the anode exhaust gas discharged from the anode 4 also contains flammable components such as hydrogen. If fuel gas is not generated in the reforming unit 9, the raw fuel gas flows through the fuel gas supply passage 16, in which case the anode exhaust gas discharged from the anode 4 contains the raw fuel gas. Oxygen is also contained in the cathode exhaust gas discharged from the cathode 6. The combustion unit 10 receives the anode exhaust gas from the fuel cell unit 7 via the anode exhaust gas passage 18, and the cathode exhaust gas from the fuel cell unit 7 via the cathode exhaust gas passage 19. In the combustion unit 10, the anode exhaust gas discharged from the anode 4 and the cathode exhaust gas discharged from the cathode 6 are supplied to burn the flammable components contained in the anode exhaust gas. Ignition of the flammable components is performed by the igniter 12. The heat of combustion generated in the combustion unit 10 raises the temperature of the internal space of the container 1. In addition, the combustion exhaust gas is supplied to the heat exchange section 11, where heat is transferred to the vaporization section 8 and the reforming section 9. The combustion exhaust gas discharged from the heat exchange section 11 is discharged to the outside of the container 1 via a combustion catalyst section 34 located in the combustion exhaust gas passage 22 downstream of the heat exchange section 11. In the combustion catalyst section 34, hydrogen, hydrocarbons, carbon monoxide, etc., contained in the gas flowing through the combustion exhaust gas passage 22 are catalytically combusted using oxygen. The operation of the igniter 12 is controlled by the operation control unit 13.

[0027] The fuel cell system of this embodiment includes a raw fuel gas heating unit 28 that can heat the raw fuel gas supplied to the reforming unit 9, an oxidant gas heating unit 30 that can heat the oxidant gas supplied to the cathode 6, an anode exhaust gas temperature sensor 32 that measures the temperature of the anode exhaust gas, and a cathode exhaust gas temperature sensor 33 that measures the temperature of the cathode exhaust gas. For example, the raw fuel gas heating unit 28 and the oxidant gas heating unit 30 are configured using electric heaters. Alternatively, the raw fuel gas heating unit 28 and the oxidant gas heating unit 30 may use combustion-type equipment that generates heat by burning combustion. The operation of the raw fuel gas heating unit 28 and the oxidizer gas heating unit 30 is controlled by the operation control unit 13. For example, the operation control unit 13 controls the operation of the raw fuel gas heating unit 28 and the oxidizer gas heating unit 30 so that the necessary temperature conditions, which will be described later, are met.

[0028] Then, the operation control unit 13 terminates the pretreatment when, while the water supply unit 27 is not supplying water to the reforming unit 9, and the raw fuel gas supplied by the raw fuel gas supply unit 23 is being heated using the raw fuel gas heating unit 28 while the raw fuel gas is being supplied to the reforming unit 9, and the oxidizer gas supplied by the oxidizer gas supply unit 24 is being heated using the oxidizer gas heating unit 30 while the oxidizer gas is being supplied to the cathode 6, the necessary temperature conditions are met, including at least the temperature of the anode exhaust gas being at or above the first set temperature and the temperature of the cathode exhaust gas being at or above the second set temperature. The operation control unit 13 then starts the startup process in which the water supply unit 27 supplies water to the reforming unit 9. For example, the contents of the necessary temperature conditions are stored in the storage unit 14, and the operation control unit 13 controls the operation of each unit by referring to the contents of the necessary temperature conditions stored in the storage unit 14.

[0029] Figure 2 is a flowchart illustrating the startup process. In process #10, the operation control unit 13 operates the raw fuel gas heating unit 28 and the oxidizer gas heating unit 30, while simultaneously operating the raw fuel gas supply unit 23 and the oxidizer gas supply unit 24, thereby supplying the heated raw fuel gas and air to the vaporization unit 8 and the reforming unit 9. Since the operation control unit 13 does not operate the water supply unit 27, no water is supplied to the reforming unit 9. As a result, even if moisture is present in the raw fuel gas and air flow paths, it is expected that this moisture will be removed.

[0030] Then, in step #11, the operation control unit 13 determines whether the required temperature conditions are met. Specifically, the operation control unit 13 refers to the measurement results of the anode exhaust gas temperature sensor 32 and the measurement results of the cathode exhaust gas temperature sensor 33 to determine whether the required temperature conditions are met, including that the temperature of the anode exhaust gas is at or above the first set temperature and the temperature of the cathode exhaust gas is at or above the second set temperature. For example, the first set temperature and the second set temperature are temperatures of 100°C or higher. In other words, the operation control unit 13 determines that the above required temperature conditions are met when the anode 4 and cathode 6 of the fuel cell unit 7 are exposed to a gas of at least 100°C or higher.

[0031] The above required temperature conditions can be set as appropriate. For example, the fuel cell system of this embodiment includes a raw fuel gas temperature sensor 29 that can measure the temperature of the raw fuel gas after it has been heated in the raw fuel gas heating unit 28 and before it is supplied to the reforming unit 9, and an oxidant gas temperature sensor 31 that can measure the temperature of the oxidant gas after it has been heated in the oxidant gas heating unit 30 and before it is supplied to the cathode 6. Therefore, the operation control unit 13 can know the temperature difference of the raw fuel gas before and after it passes through the vaporization unit 8, the reforming unit 9 and the fuel cell unit 7, and the temperature difference of the oxidant gas before and after it passes through the fuel cell unit 7. The operation control unit 13 can determine that the necessary temperature conditions are met when the temperature of the anode exhaust gas is above the first set temperature, the temperature of the cathode exhaust gas is above the second set temperature, the temperature difference between the temperature of the raw fuel gas measured by the raw fuel gas temperature sensor 29 and the temperature of the anode exhaust gas measured by the anode exhaust gas temperature sensor 32 is within a predetermined first temperature difference, and the temperature difference between the temperature of the oxidizer gas measured by the oxidizer gas temperature sensor 31 and the temperature of the cathode exhaust gas measured by the cathode exhaust gas temperature sensor 33 is within a predetermined second temperature difference.

[0032] Then, if the operation control unit 13 determines that the above required temperature conditions are met (if the answer is "Yes" in step #11), it proceeds to step #12, where it activates the water supply unit 27 to supply water to the vaporization unit 8 and activates the igniter 12 to initiate combustion in the combustion unit 10. As a result, the startup process is initiated and steam reforming in the reforming unit 9 begins.

[0033] As described above, before the water supply unit 27 starts the startup process of supplying water to the reforming unit 9, a pre-treatment is performed in which the water supply unit 27 does not supply water to the reforming unit 9, and the raw fuel gas supplied by the raw fuel gas supply unit 23 is heated using the raw fuel gas heating unit 28 while the raw fuel gas is supplied to the reforming unit 9, and the oxidizer gas supplied by the oxidizer gas supply unit 24 is heated using the oxidizer gas heating unit 30 while the oxidizer gas is supplied to the cathode 6. This pre-treatment is performed until the necessary temperature conditions are met, including at least the temperature of the anode exhaust gas being at or above the first set temperature and the temperature of the cathode exhaust gas being at or above the second set temperature. In other words, heated raw fuel gas that does not contain moisture flows through the anode 4 and the gas flow paths upstream and downstream of it, so even if moisture remains there, that moisture is removed by the flow of raw fuel gas at or above the first set temperature (i.e., high temperature). Furthermore, since moisture-free oxidizing gas flows through the cathode 6 and the gas channels upstream and downstream of it, any moisture that remains there will be removed by the flow of oxidizing gas at or above the second set temperature (i.e., high temperature). After the gas channels upstream and downstream of the anode 4, and the gas channels upstream and downstream of the cathode 6, have reached a high temperature (i.e., a state where water condensation does not occur), the startup process in which the water supply unit 27 supplies water to the reforming unit 9 is initiated.

[0034] <Another Embodiment> In the above embodiment, specific examples of the fuel cell system configuration have been given, but the configuration can be modified as appropriate.

[0035] In the above embodiment, the content of the required temperature conditions can be changed as appropriate. For example, the operation control unit 13 may control the operation of the raw fuel gas heating unit 28 and the oxidizer gas heating unit 30 so as to satisfy the required temperature conditions, which include the anode exhaust gas temperature being above a first set temperature and below a third set temperature (e.g., 100°C or higher and 200°C or lower), and the cathode exhaust gas temperature being above a second set temperature and below a fourth set temperature (e.g., 100°C or higher and 200°C or lower). Alternatively, the required temperature condition may be that the temperature of the anode exhaust gas is above the first set temperature, and the temperature of the cathode exhaust gas is above the second set temperature, and this condition continues for a set period of time or longer.

[0036] The configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Furthermore, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto and can be modified as appropriate without departing from the purpose of the present invention. [Industrial applicability]

[0037] This invention can be used in fuel cell systems that can prevent the fuel cell system from being started while condensation is present, and can also prevent condensation from occurring during startup. [Explanation of symbols]

[0038] 3: Fuel cell 4: Anode 5: Electrolyte 6: Cathode 7:Fuel cell section 9: Modification section 10: Combustion section 13: Operation Control Unit 23: Raw Material and Fuel Gas Supply Department 24: Oxidizer gas supply unit 27:Water supply section 28: Raw fuel gas heating section 29: Raw fuel gas temperature sensor 30: Oxidizing agent gas heating section 31: Oxidizing gas temperature sensor 32: Anode exhaust gas temperature sensor 33: Cathode exhaust gas temperature sensor

Claims

1. A raw fuel gas supply unit that supplies raw fuel gases containing hydrocarbons, A reforming unit that steam reforms the aforementioned raw fuel gas to produce a fuel gas containing hydrogen, A water supply unit that supplies water used in the steam reforming process, A fuel cell unit comprising a fuel cell cell having an anode to which the fuel gas generated in the reforming unit is supplied, a cathode to which an oxidizing gas is supplied, and an electrolyte provided between the anode and the cathode, An oxidizing gas supply unit that supplies the oxidizing gas to the cathode, A combustion section is supplied with anode exhaust gas discharged from the anode and cathode exhaust gas discharged from the cathode, which can burn the combustible components contained in the anode exhaust gas. It includes an operation control unit, A fuel cell system configured such that the heat of combustion generated in the combustion section is transferred to the reforming section, A raw fuel gas heating unit capable of heating the raw fuel gas supplied to the reforming unit, An oxidizing agent gas heating unit capable of heating the oxidizing agent gas supplied to the cathode, An anode exhaust gas temperature sensor that measures the temperature of the anode exhaust gas, The system includes a cathode exhaust gas temperature sensor for measuring the temperature of the cathode exhaust gas, The aforementioned operation control unit, A fuel cell system in which, while the water supply unit does not supply water to the reforming unit, and the raw fuel gas supplied by the raw fuel gas supply unit is supplied to the reforming unit while the raw fuel gas is heated using the raw fuel gas heating unit, and the oxidizer gas supplied by the oxidizer gas supply unit is supplied to the cathode while the oxidizer gas is heated using the oxidizer gas heating unit, a pretreatment is performed, and when the necessary temperature conditions are met, including at least the temperature of the anode exhaust gas being at or above a first set temperature and the temperature of the cathode exhaust gas being at or above a second set temperature, the pretreatment is terminated and the water supply unit starts a start-up process in which it supplies water to the reforming unit.

2. A raw fuel gas temperature sensor capable of measuring the temperature of the raw fuel gas after it has been heated in the raw fuel gas heating section and before it is supplied to the reforming section, The system includes an oxidant gas temperature sensor capable of measuring the temperature of the oxidant gas after it has been heated in the oxidant gas heating section and before it is supplied to the cathode. The aforementioned operation control unit, The fuel cell system according to claim 1, wherein the required temperature conditions are determined to be met when the temperature of the anode exhaust gas is equal to or greater than the first set temperature, the temperature of the cathode exhaust gas is equal to or greater than the second set temperature, the temperature difference between the temperature of the raw fuel gas measured by the raw fuel gas temperature sensor and the temperature of the anode exhaust gas measured by the anode exhaust gas temperature sensor is within a predetermined first temperature difference, and the temperature difference between the temperature of the oxidizer gas measured by the oxidizer gas temperature sensor and the temperature of the cathode exhaust gas measured by the cathode exhaust gas temperature sensor is within a predetermined second temperature difference.

3. The fuel cell system according to claim 1 or 2, wherein the raw fuel gas heating section and the oxidizer gas heating section are configured using electric heaters.

4. The fuel cell system according to claim 1 or 2, wherein the first set temperature and the second set temperature are temperatures of 100°C or higher.

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