JP2008108446A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system effective to suppress equipment from becoming complex and large by reducing or abolishing any other supply sources than the raw fuel supply source. <P>SOLUTION: The fuel cell system comprises a reformer 2 for reforming raw fuel and generating a reformed fluid containing an active substance, a fuel cell 1 for performing power generating reaction using a fluid reformed by the reformer 2 and an oxidizer fluid, a fluid channel for communicating the reformer 2 with the fuel cell 1, and a diagnostic means for checking for leakage of the raw fuel. The diagnostic means supplies the raw fuel to the reformer 2 or fluid channel without reforming the raw fuel and checks for leakage in the downstream region of at least a reforming section 34 among the reformer 2 and fluid channel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system equipped with a reformer for reforming raw fuel.

In order to operate the fuel cell system satisfactorily, it is preferable to detect a gas leak in the piping passage. Therefore, a method of detecting gas leakage by using helium gas as a detection gas and supplying the helium gas to a fuel gas passage or an oxidizer passage and sealing the gas is disclosed (Patent Document 1). Furthermore, a fuel cell evaluation apparatus that performs leak diagnosis using inexpensive nitrogen gas as a detection gas is known (Patent Document 2).
JP 2002-334713 A Japanese Patent Laid-Open No. 5-205762

  According to the above-described technology, in addition to the fuel supply source of raw fuel used in the power generation operation, a supply source such as a tank for storing helium and a tank for storing nitrogen gas is required in the fuel cell system. In this case, the facility becomes complicated and large.

  The present invention has been made in view of the above-described circumstances, and provides a fuel cell system that is advantageous for reducing or eliminating the supply sources other than the fuel supply source of raw fuel, thereby suppressing the complexity and size of facilities. The issue is to provide.

  (1) A fuel cell system according to aspect 1 includes a reformer that generates a reformed fluid containing an active material by reforming raw fuel, and a reformer that is reformed by a reforming unit of the reformer A fuel cell that performs a power generation reaction based on a fluid and an oxidant fluid, a fluid passage that communicates the reforming unit of the reformer with the fuel cell and supplies the reformed fluid to the fuel cell, and diagnoses leakage of raw fuel The diagnostic means supplies the reformed fuel and / or the fluid passage without reforming the raw fuel, and at least downstream of the reformer and the fluid passage. It is characterized by diagnosing raw fuel leakage in the region.

  The diagnostic means diagnoses leakage of raw fuel (raw fuel before reforming) that is a fluid. In this case, the diagnostic means detects the leakage of the raw fuel that is a fluid by supplying the raw fuel to the reformer and / or the fluid passage without reforming the raw fuel. As a result, the diagnostic means diagnoses the leakage of raw fuel in at least the region downstream of the reforming unit in the reformer and the fluid passage. A region downstream of the reforming unit includes a fuel cell.

  (2) A fuel cell system according to aspect 2 includes a reformer that generates a reformed fluid containing an active material by reforming raw fuel, and a reformed fluid and an oxidant that are reformed by the reformer A fuel cell that performs a power generation reaction based on the fluid, a fluid passage that communicates the reforming unit of the reformer with the fuel cell and supplies the reformed fluid to the fuel cell, and diagnostic means for diagnosing leakage of raw fuel The diagnostic means supplies the raw fuel to the fuel cell without reforming the raw fuel, and diagnoses the leakage of the raw fuel in the fuel cell.

  The diagnostic means diagnoses leakage of raw fuel (raw fuel before reforming) that is a fluid. In this case, the diagnosis unit detects whether or not the raw fuel leaks in the fuel cell by supplying the raw fuel to the fuel cell without reforming the raw fuel.

  According to the fuel cell system according to aspect 1, the diagnostic means supplies the raw fuel, which is a fluid, to the reforming device or the fluid passage without reforming, and at least the reforming unit of the reforming device and the fluid passage. Diagnose leaks in the downstream area. According to the aspect 1, since the diagnosis is performed without reforming the raw fuel that is a fluid, it is not necessary to install a tank dedicated to leak diagnosis that encloses an inert gas such as nitrogen gas or helium gas for leak diagnosis. For this reason, the complexity and enlargement of the structure of the fuel cell system are suppressed.

  According to the fuel cell system according to aspect 2, the diagnostic means supplies the raw fuel, which is a fluid, to the fuel cell without reforming. The diagnosis means diagnoses leakage of raw fuel in the fuel cell. According to the aspect 2, since the diagnosis is performed without reforming the raw fuel, it is not necessary to mount a tank dedicated for leak diagnosis in which an inert gas such as nitrogen gas or helium gas for leak diagnosis is enclosed. For this reason, the complexity and enlargement of the structure in the fuel cell system are suppressed.

  The fuel cell system according to the present invention includes a reformer, a fuel cell, a fluid passage, and diagnostic means. The reformer generates a reformed fluid containing an active material (a substance that contributes to a power generation reaction) by reforming the raw fuel in a normal power generation operation. The raw fuel means a raw material that becomes a reforming fluid (generally a reformed gas). Examples of the raw fuel described above include hydrocarbon fuels (methane, propane, butane, etc.) and alcohol fuels (ethanol, methanol, etc.), which may be gaseous or liquid.

  The fuel cell performs a power generation reaction based on the reformed fluid and the oxidant fluid reformed by the reformer. Examples of the reforming fluid include hydrogen-containing gas and hydrogen gas. The oxidant fluid is exemplified by oxygen gas, oxygen-containing gas, and air. The fuel cell may be a type in which sheet-type cells are stacked in the thickness direction or a type in which a plurality of tube-type cells are mounted. The fluid passage allows the reformer and the anode electrode of the fuel cell to communicate with each other.

  The diagnostic means according to aspect 1 supplies the raw fuel to the reformer and / or the fluid passage without reforming the raw fuel, and leakage of the raw fuel at least in the region downstream of the reforming unit of the reformer and the fluid passage. Diagnose. In this case, the raw fuel is preferably supplied to the reformer and / or the fluid passage in a pressurized state of atmospheric pressure or higher.

  A pressure detection unit is provided in a region downstream or upstream of the reformer, and the diagnosis unit is configured to diagnose raw fuel leakage based on the pressure detection unit detecting a pressure drop. . In this case, diagnosis of leakage of raw fuel is performed based on detection of a pressure drop by the pressure detection means. Moreover, the form in which the raw fuel detection means is provided outside the reformer and the fluid passage is exemplified. The raw fuel detection means detects substances contained in the raw fuel. In this case, based on the fact that the raw fuel detection means detects a substance contained in the raw fuel, a form in which the diagnosis means diagnoses leakage of the raw fuel is exemplified. In this case, diagnosis of leakage of the raw fuel is performed based on detection of a substance contained in the raw fuel.

  The diagnostic means according to aspect 2 supplies the raw fuel to the anode electrode of the fuel cell without reforming, and diagnoses leakage at the anode electrode of the fuel cell. The diagnostic means according to aspect 2 supplies the raw fuel to the anode electrode of the fuel cell without reforming, and diagnoses the leakage of the raw fuel at the anode electrode of the fuel cell. In this case, the raw fuel is preferably supplied to the anode electrode of the fuel cell in a pressurized state at atmospheric pressure or higher. Pressure detecting means is provided in a region communicating with the anode electrode of the fuel cell, and based on the pressure detecting means detecting the pressure drop of the raw fuel, the diagnostic means diagnoses the leakage of the raw fuel in the fuel cell. The form to perform is illustrated. A raw fuel detection means is provided outside the fuel cell, and based on the raw fuel detection means detecting a substance contained in the raw fuel, the diagnosis means diagnoses the leakage of the raw fuel in the fuel cell. The form to perform is illustrated.

  The raw fuel containing sulfur components may become a poisonous substance in the reformer or the fuel cell. Therefore, a desulfurizer for desulfurizing the raw fuel is provided in the fuel cell system, and a mode in which the raw fuel that has passed through the desulfurizer is used for leakage diagnosis is exemplified. Therefore, a pretreatment purification unit for purifying harmful components contained in the raw fuel in advance is provided in the fuel cell system, and a mode in which the raw fuel purified by passing through the pretreatment purification unit is used for leakage diagnosis is exemplified.

  An example of the fluid passage is provided with a CO reduction unit that reduces carbon monoxide contained in the reforming fluid. Examples of the CO reduction unit include one or both of a CO shift unit that reduces carbon monoxide by a shift reaction and a CO selective oxidation unit that oxidizes and reduces carbon monoxide.

  Examples of the diagnostic means include supplying the fuel cell to the fuel cell without reforming the raw fuel, and diagnosing leakage of the raw fuel in the fuel cell. In this case, when the supply pressure of the raw fuel supplied in the diagnosis of leakage in the fuel cell is Pc and the supply pressure of the raw fuel supplied in the diagnosis of leakage in the reformer is Pr, If necessary, Pc = Pr and Pc≈Pr may be set, or Pc> Pr and Pc <Pr may be set.

  According to the present invention, the fluid passage is provided between the reformer and the fuel cell and extends from the anode gas passage for supplying raw fuel to the inlet of the anode of the fuel cell and the outlet of the anode of the fuel cell. A first cutoff valve capable of shutting off the raw fuel from the anode gas passage toward the inlet of the anode of the fuel cell, and a first shutoff valve capable of shutting off the raw fuel from the outlet of the anode of the fuel cell toward the offgas passage. The form provided with 2 shut-off valves is illustrated. In this case, the diagnosis means performs (i) a first diagnosis of leakage in a region downstream of the reformer with the first shut-off valve closed so that raw fuel is not supplied to the fuel cell, and (ii) ) A mode is illustrated in which the raw fuel is supplied to the anode electrode of the fuel cell and the leakage of the anode electrode of the fuel cell is diagnosed by closing the second cutoff valve and opening the first cutoff valve.

  According to the present invention, the fluid passage is provided between the reformer and the fuel cell, the anode gas passage supplying the reformed fluid to the inlet of the anode of the fuel cell, and the outlet of the anode of the fuel cell. An extended off-gas passage, a bypass passage connecting the anode gas passage and the off-gas passage, a first shut-off valve capable of shutting off raw fuel from the anode gas passage toward the anode electrode of the fuel cell, and an anode of the fuel cell Examples include a second shut-off valve capable of shutting off the raw fuel from the pole outlet toward the off-gas passage and a third shut-off valve capable of shutting off the raw fuel from the anode gas passage toward the off-gas passage. In this case, the diagnostic means (i) closes at least downstream of the reforming unit of the reformer and the fluid passage with the first shut-off valve and the third shut-off valve closed so that the raw fuel is not supplied to the fuel cell. Supplying a raw fuel to the anode electrode of the fuel cell by performing a first diagnosis of leakage in the region and (ii) closing the second and third shut-off valves and opening the first shut-off valve; The form which diagnoses the leak of a fuel cell is illustrated.

  Further, according to the present invention, the combustion unit that heats the reforming unit by combustion is provided, and the combustion unit is provided in the region downstream of the reforming unit of the reforming device and the outlet of the anode electrode of the fuel cell. The form which is communicating is illustrated. In this case, at the time of diagnosis, the diagnostic means burns in the combustion section by supplying raw fuel discharged from the region downstream of the reforming section of the reformer or the anode electrode outlet of the fuel cell to the combustion section. The form to make is illustrated. When the combustion part is ignited, the raw fuel used for the leakage diagnosis can be burned in the combustion part. In this case, unlike the inert gas such as nitrogen gas, the raw fuel has a combustion component. Therefore, even if the raw fuel is supplied to the combustion portion, blow-off (extinguishing) of the combustion portion is suppressed. In addition, when the combustion part is not ignited, the diagnosis means supplies the air to the combustion part so that the raw fuel is diluted with air without being burned and discharged outward from the combustion part. .

  The leak diagnosis is performed before the fuel cell system is shipped, immediately before the start of the fuel cell system, when pipes and parts are replaced after shipment, when pipes and parts are replaced after shipment, and when the fuel cell system is replaced. The maintenance time is illustrated. The time when the leakage diagnosis is executed is preferably when the power generation operation is not performed.

By the way, when the time has not passed so much since the end of the previous reformer operation, there is a possibility that the reforming section is still at a high temperature. When raw fuel is supplied to a high temperature reforming section for leak diagnosis, coking may occur in the catalyst of the reforming section. In this case, catalyst pulverization and an increase in pressure loss may be induced. In this regard, according to the present invention, when the reforming device of the fuel cell system is started for the first time after the leakage diagnosis, the diagnosis means has a value of S / C related to the reforming device rather than at the time of normal starting of the reforming device. The form which sets high is illustrated. In this case, H ₂ O becomes rich, which is advantageous for reducing coking. Here, the value of S / C is (number of moles of H ₂ O contained in reformed water supplied to reformer) / (number of moles of carbon component contained in raw fuel supplied to reformer) ).

  Further, when a predetermined time has not elapsed since the end of the previous operation of the reformer, or when the temperature of the reforming unit is a high temperature exceeding a predetermined temperature (for example, 400 ° C.), the raw fuel is used for leak diagnosis. If is supplied to the reforming section, coking may occur in the reforming section. In this regard, according to the present invention, when a predetermined time has elapsed since the end of the previous operation of the reformer, or when the temperature of the reforming unit is lower than the predetermined temperature, the diagnosis means performs a raw fuel leak diagnosis. When the predetermined time (for example, 4 hours) has not elapsed since the last operation of the reformer is performed, or when the temperature of the reforming unit is equal to or higher than the predetermined temperature, the diagnosis unit performs raw fuel leakage diagnosis. The form which does not perform is illustrated. In this case, coking in the reforming unit is suppressed.

  The diagnostic means serves as a purging fluid (filling fluid) in the reforming device and / or the fluid passage without reforming the raw fuel so that the reforming device and the fluid passage purge processing (sealing processing) are combined. Supplying and diagnosing leakage of raw fuel in at least the region downstream of the reforming unit of the reformer and the fluid passage may be performed. If there is no fluid leakage, the raw fuel is directly enclosed in the reformer and the fluid passage as a purge fluid (filling fluid). Alternatively, the first shut-off valve is opened to leave the raw fuel corresponding to about atmospheric pressure in the reformer and the fluid passage, and then the first shut-off valve is closed to feed the raw fuel fluid to the reformer and the fluid passage. It may be enclosed in.

  Further, the diagnostic means supplies the purge fluid (encapsulating fluid) to the anode and / or cathode of the fuel cell without reforming the raw fuel so as to also perform the purge processing (encapsulation) of the fuel cell. In addition, the leakage of raw fuel at the anode and / or cathode of the fuel cell may be diagnosed. If there is no leakage, the raw fuel is directly sealed in the anode electrode and the fluid passage of the fuel cell as a purge fluid (filling fluid). The purge process of the fuel cell is a process in which raw fuel is supplied into the fuel cell and the gas remaining in the fuel cell is completely or almost completely expelled. The fuel cell sealing process is a process of sealing in a state where raw fuel is supplied into the fuel cell.

  Or you may open a 3rd cutoff valve for predetermined time (for example, about 1-2 second). In this case, the raw fuel gas of the atmospheric pressure or more escapes, and the raw fuel fluid at atmospheric pressure remains in the anode electrode and the fluid passage of the fuel cell, and the third shut-off valve is closed, and the raw fuel fluid is removed from the anode electrode and the fluid. It may be enclosed in a passage. That is, the diagnostic means exemplifies a form of performing a sealing operation in which the raw fuel is sealed in the reformer and / or the fuel cell as a purge fluid (filling fluid) if no leakage is detected.

(Overall description of examples)
Embodiment 1 of the present invention will be specifically described below with reference to FIGS. The reformer according to the present embodiment is applied to a fuel cell system. As shown in FIG. 1, the fuel cell 1 has a proton conductive solid polymer membrane 10 (ion conducting membrane) sandwiched between an anode 11 (fuel electrode) and a cathode 12 (oxidant electrode) in the thickness direction. A plurality of membrane electrode assemblies 13 to be assembled are assembled. Examples of the material of the solid polymer film 10 include a fluorocarbon resin (for example, perfluorosulfonic acid resin) or a hydrocarbon resin. The fuel cell 1 may be a system in which a plurality of sheet-like membrane electrode assemblies 13 are stacked in the thickness direction, or a system in which a plurality of tube-shaped membrane electrode assemblies 13 are arranged.

  As shown in FIG. 1, the reformer 2 includes a combustion section 30 formed of a combustion burner, a reforming section 34 heated by the combustion section 30, and a cylindrical combustion passage 32 facing the combustion section 30. The combustion passage 33 communicating with the combustion passage 32, the cylindrical combustion passage 35 communicating with the combustion passage 33, the cylindrical evaporation portion 36 for evaporating the raw water, and the cylindrical CO oxidation removal portion 37 (CO reduction) Part).

  As shown in FIGS. 1 and 2, the reforming section 34 is disposed between the combustion passage 32 and the combustion passage 33, and has an inner passage 34i, an outer passage 34p, and a turn-up portion 34m. A cylindrical combustion passage 33 is arranged so as to surround the reforming section 34. The combustion passage 35 is a cylindrical passage that is folded back from the combustion passage 33. A cylindrical heat insulating portion 31 is disposed between the cylindrical combustion passages 33 and 35. Further, a cylindrical evaporator 36 is arranged so as to surround the combustion passage 35. The combustion passage 35 is disposed on the inner peripheral side of the evaporator 36. The evaporator 36 is heated by the combustion gas that passes through the combustion passage 35. A CO oxidation removal unit 37 (CO reduction unit) is arranged so as to surround the evaporation unit 36. Therefore, the evaporation unit 36 and the CO oxidation removal unit 37 are mutually heat-exchanged.

  During the steady operation of the reformer 2, the CO oxidation removing unit 37 is higher in temperature than the evaporation unit 36, so the CO oxidation removing unit 37 applies heat to the evaporation unit 36. Note that until the temperature of the CO oxidation removal unit 37 reaches about 100 ° C. during the start-up operation and after all the water in the evaporation unit 36 of the evaporation unit 36 is vaporized during the stop operation, the CO oxidation removal unit is removed from the evaporation unit 36. 37 is heated. On the outer periphery of the CO oxidation removing portion 37, a heat insulating cylindrical heat insulating layer 39 is disposed.

  The reforming unit 34 includes a ceramic carrier that supports a reforming catalyst 34e that promotes a reforming reaction. The active temperature range of the reforming catalyst 34e is generally 500 to 800 ° C., but is not limited thereto. If the temperature of the reforming unit 34 deviates greatly from the activation temperature range, the reforming reaction of the reforming unit 34 may be impaired. The reforming unit 34 performs steam reforming based on the reforming fuel and steam based on the following formula (1) to generate reformed gas containing hydrogen as a main component. The reformed gas contains carbon monoxide.

  In the reforming section 34, the following formula (2) is also generated, and carbon monoxide is reduced. Further, as shown in FIG. 1, the reformer 2 includes a heat exchange unit 4 disposed below the reforming unit 34, a CO shift unit 5 disposed below the heat exchange unit 4, and a CO shift unit. 5 and a warm-up unit 47 disposed between the heat exchange unit 4. Here, the heat exchange unit 4 is provided downstream of the evaporation unit 36, and the CO shift unit 5 is provided downstream of the heat exchange unit 4.

  The CO shift unit 5 promotes a shift reaction using water vapor based on the following formula (2), and reduces CO contained in the reformed gas. The CO shift unit 5 includes a ceramic carrier that supports a shift catalyst 5e (for example, a copper-zinc catalyst). The active temperature range of the shift catalyst 5e is generally 200 to 300 ° C., but is not limited thereto. If the temperature of the CO shift unit 5 greatly deviates from the activation temperature range, the shift reaction of the CO shift unit 5 may be impaired, and carbon monoxide may not be sufficiently purified. The concentration of CO contained in the reformed gas purified by the CO shift unit 5 is generally 0.2 to 1% in terms of molar ratio, although it depends on the reforming fuel. It is not something that can be done. The CO shift unit 5 has a passage 5i, a passage 5v, and a turning portion 5m. The outlet 5p of the CO shift unit 5 and the oxidation air passage 75 are connected by a purification passage 400 via the second merge region M2.

As shown in FIG. 1, the CO oxidation removal unit 37 is disposed downstream of the CO shift unit 5, and CO contained in the reformed gas that has passed through the CO shift unit 5 is converted into carbon dioxide as the following formula ( Based on 3), the oxidation reaction to be reduced by oxidation is promoted. The CO oxidation removing unit 37 includes a ceramic carrier that supports a selective oxidation catalyst 37e (for example, ruthenium-based). The active temperature range of the selective oxidation catalyst 37e is generally 100 to 200 ° C. However, it is not limited to this. If the temperature of the CO oxidation removing unit 37 is greatly deviated from the activation temperature range, the oxidation reaction in the CO oxidation removing unit 37 may be impaired. The concentration of CO contained in the reformed gas purified by the CO oxidation removing unit 37 is generally 10 ppm or less in terms of molar ratio. However, it is not limited to this.
Formula (1) ... CH ₄ + H ₂ O → 3H ₂ + CO
Formula (2) ... CO + H ₂ O → H ₂ + CO ₂
Formula (3) ... CO + 1 / 2O ₂ → CO ₂

  According to the present embodiment, since the CO shift unit 5 is arranged upstream of the CO oxidation removal unit 37, it is executed in the order of Expression (2) → Expression (3).

  Next, the passage system will be described. As shown in FIG. 1, a fuel passage 62 connected to the fuel supply source 61 through a valve 25a is provided. The raw fuel of the fuel supply source 61 may be gaseous fuel, liquid fuel, or pulverized fuel. Specifically, hydrocarbon fuel and alcohol fuel are exemplified. Examples include city gas, LPG, kerosene, methanol, ethanol, dimethyl ether, and biogas. The fuel passage 62 is connected to the combustion fuel passage 62 connected to the combustion section 30 of the reforming section 34 via the valve 25a and the pump 27a, and to the inlet 4i of the heat exchange section 4 via the pump 27b, the desulfurizer 62x and the valve 25b. It has a reforming fuel passage 62 (reforming fuel supply section) that is connected. The desulfurizer 62x functions as a pretreatment purification unit that reduces and purifies sulfur components that are harmful components contained in the raw fuel. An air passage 72 (oxygen supply unit) connected to the air supply source 71 is provided. The air passage 72 is connected to the combustion air passage 73 connected to the combustion portion 30 of the reforming portion 34 via the pump 27c, and the oxidation air passage 75 connected to the inlet 37i of the CO oxidation removal portion 37 via the pump 27d and the valve 25d. And have.

  As shown in FIG. 1, a reforming water passage 82 (reforming water supply unit) that connects the water tank 81 and the inlet 36i of the evaporation unit 36 via a pump 27m and a valve 25m is provided. An anode gas passage 100 that connects the outlet 37p of the CO oxidation removing unit 37 and the inlet 11i of the anode 11 of the fuel cell 1 via a valve 25e is provided. The outlet 37p of the CO oxidation removing unit 37 is formed on the upper side of the CO oxidation removing unit 37 in the height direction. An off-gas passage 110 that connects the outlet 11p of the anode 11 of the fuel cell 1 and the combustion unit 30 via a valve 25f is provided. The off gas passage 110 discharges the anode off gas after the power generation reaction to the combustion unit 30. A bypass passage 150 that connects the off gas passage 110 and the anode gas passage 100 via the valve 25h is provided. As shown in FIG. 1, a pressure sensor 100 x is provided as pressure detection means for detecting the pressure of the reformer 2. The pressure sensor 100x is disposed in a branch region between the bypass passage 150 and the anode gas passage 100, but is not limited thereto.

  As shown in FIG. 1, a cathode gas passage 200 communicating with the air supply source 71 and the inlet 12i of the cathode electrode 12 of the fuel cell 1 via a pump 27k and a valve 25k is provided. A combustion exhaust gas passage 250 for releasing the combustion exhaust gas combusted in the combustion unit 30 to the outside is provided. A water vapor passage 300 is provided that connects the outlet 36p of the evaporation section 36 and the reforming fuel passage 62 via the first merge region M1. The upper end portion 300e of the water vapor passage 300 is connected to the outlet 36p. The lower end portion 300f of the water vapor passage 300 is connected to the merge area M1.

  As shown in FIG. 1, the outlet 5 p of the CO shift unit 5 and the inlet 37 i of the CO oxidation removing unit 37 are connected by a purification passage 400. The reformed gas (containing hydrogen and carbon monoxide) discharged from the outlet 5p of the CO shift unit 5 flows upward in the direction of the arrow W2 through the purification passage 400, passes through the second merging zone M2, and flows through the CO oxidation removal unit 37. It is supplied to the inlet 37i. The inlet 37 i is formed on the lower side in the height direction of the CO oxidation removing unit 37.

  FIG. 4 is a block diagram showing the concept of the fuel cell system. As shown in FIG. 4, basically, the first passage 4a of the heat exchange section 4, the reforming section 34, the second passage 4c of the heat exchange section 4, the CO shift section 5, the CO oxidation removal section 37, the anode gas The passage 100, the pressure sensor 100x, the valve 25e, the anode 11 of the fuel cell 1, the valve 25f, the off-gas passage 110, and the combustion unit 30 are arranged in series. Therefore, the fluid passage connecting the reforming unit 34 and the fuel cell 1 corresponds to the second passage 4 c of the heat exchange unit 4, the CO shift unit 5, the CO oxidation removal unit 37, and the anode gas passage 100.

  Next, a case where the fuel cell system is started will be described. In this case, combustion air is supplied to the combustion unit 30 via the combustion air passage 73 by the pump 27c. Further, the combustion fuel (raw fuel) is supplied to the combustion unit 30 through the combustion fuel passage 62 by the valve 25a and the pump 27a. As a result, the combustion section 30 is ignited and heated by the igniter, and as a result, the reforming section 34 is heated so as to be suitable for the reforming reaction. The reformer 34 and the evaporator 36 are also heated to a high temperature.

  Thereafter, the reformed water is supplied from the water tank 81 and the reformed water passage 82 to the inlet 36i of the high-temperature evaporator 36 through the pump 27m and the valve 25m. The reformed water is steamed in the high temperature evaporation section 36. The generated water vapor reaches the first merge region M1 through the water vapor passage 300 from the outlet 36p of the evaporation section 36. The first merge region M1 is a region where the steam or condensed water flowing through the steam passage 300 and the reforming fuel flowing through the reforming fuel passage 62 merge. The reforming fuel is supplied to the inlet 4i of the heat exchanging section 4 through the reforming fuel passage 62 and the first junction region M1 by the valve 25a, the pump 27b, and the valve 25b. Therefore, in the first merge region M1, the raw fuel that is the reforming fuel in the reforming fuel passage 62 and the steam in the steam passage 300 are merged and mixed. The merged mixed fluid is supplied to the inlet 4 i of the heat exchange unit 4. The mixed fluid passes through the first passage 4 a on the low temperature side of the heat exchange unit 4. At this time, heat exchange is performed with the high-temperature reformed gas flowing through the second passage 4c on the high temperature side of the heat exchange unit 4. For this reason, the mixed fluid before the reforming reaction is heated. The mixed fluid flows into the outer passage 34p of the reforming portion 34, flows in the direction of arrow A1, flows into the inner passage 34i through the turn-up portion 34m, and flows in the direction of arrow A2. At this time, the mixed fluid in which the steam (or condensed water) and the reforming fuel are mixed becomes a hydrogen-rich reformed gas by the reforming reaction shown in (1). This reformed gas contains carbon monoxide.

  Further, the high-temperature reformed gas that has undergone the reforming reaction flows from the reforming section 34 into the heat exchanging section 4. That is, the high-temperature reformed gas passes through the second passage 4c on the high temperature side of the heat exchange unit 4 from the reforming unit 34, thereby heating the mixed fluid in the first passage 4a on the low temperature side. Further, the reformed gas flows into the CO shift unit 5 from the inlet 5 i of the CO shift unit 5 through the warm-up unit 47. In the CO shift unit 5, a shift reaction using water vapor is performed as shown in the above formula (2). As a result, the carbon monoxide contained in the reformed gas is reduced and the reformed gas is purified.

Further, the reformed gas in which carbon monoxide has been reduced in the CO shift unit 5 flows from the outlet 5p of the CO shift unit 5 through the purification passage 400 in the direction of the arrow W2 and reaches the second merge region M2. Further, the reformed gas joins the oxidizing air (oxygen component, selective oxidizing air used for the selective reaction in the CO oxidation removing unit 37) in the oxidizing air passage 75 (oxygen supply unit) in the second merge region M2. To do. The second merge region M2 is a region where the reformed gas flowing through the purification passage 400 and the oxidation air flowing through the oxidation air passage 75 merge. The merged reformed gas flows into the CO oxidation removing unit 37 from the inlet 37i. In the CO oxidation removing unit 37, an oxidation reaction (CO + 1 / 2O ₂ → CO ₂ ) using oxygen is performed as shown in the above formula (3). As a result, carbon monoxide contained in the reformed gas is further reduced. The oxidation reaction is exothermic.

  The reformed gas thus purified is supplied as an anode gas from the outlet 37p of the CO oxidation removing section 37 to the inlet 11i of the anode 11 of the fuel cell 1 through the anode gas passage 100 and the valve 25e. The air functioning as the cathode gas is supplied to the inlet 12i of the cathode electrode 12 of the fuel cell 1 through the cathode gas passage 200 by the pump 27k (air carrier source) and the valve 25k. As a result, a power generation reaction occurs in the fuel cell 1 and electric energy is generated. The off-gas after the power generation reaction of the anode gas may include hydrogen that has not undergone the power generation reaction. For this reason, the off gas is supplied to the combustion unit 30 of the reforming unit 34 through the off gas passage 110 and burned, and becomes a heat source of the combustion unit 30.

  In addition, at the time of starting the reforming apparatus 2, the stability of the reformed gas composition may not always be sufficient. For this reason, at the time of starting the reforming apparatus 2, the valve 25e (first shutoff valve) and the valve 25f (second shutoff valve) are closed. In this state, the reformed gas discharged from the outlet 37p of the CO oxidation removing unit 37 passes through the opened valve 25h (third shutoff valve), and passes through the bypass passage 150 and the off-gas passage 110 to the combustion unit 30. To be combusted and become a heat source of the combustion section 30. As time elapses from the start of the reforming device 2, the composition of the reformed gas becomes stable. In this case, the valve 25e and the valve 25f are opened, and the valve 25h is closed. For this reason, the reformed gas discharged from the outlet 37p of the CO oxidation removing unit 37 is supplied as an anode gas to the inlet 11i of the anode electrode 11 of the fuel cell 1 through the anode gas passage 100 and the valve 25e to generate a power generation reaction. used.

  As shown in FIG. 1, a CO shift unit temperature detector 55 that detects a temperature T11 on the upstream side (inlet side of the passage 5i) of the CO shift unit 5 is provided. A temperature detector 39 for detecting the temperature T31 of the CO shift unit 5 is provided. A CO oxidation removal unit temperature detector 38 for detecting the upstream temperature T12 of the CO oxidation removal unit 37 is provided. Further, a reforming unit temperature detector 31t for detecting the temperature T1 on the outlet side of the reforming unit 34 is provided. A temperature detector 65 that detects the temperature T2 of the first merge region M1 where the steam and the reforming fuel merge is provided.

  According to the present embodiment, as shown in FIG. 3, the control unit 500 includes an input processing circuit 500a, a CPU 500b, a memory 500c formed of a writable / readable non-volatile memory, a readable memory 500d, And an output processing circuit 500e. An activation switch 504 that activates the fuel cell system is provided. A stop switch 505 for stopping the power generation operation of the fuel cell system is provided. A regeneration switch 506 for starting the regeneration process of the catalyst 37e of the CO oxidation removing unit 377 is provided. A diagnosis switch 507 for starting a gas leak diagnosis using raw fuel is provided.

  A start switch 504, a stop switch 505, a regeneration switch 506, a diagnostic switch 507, a pressure sensor 100x, a reforming unit temperature detector 31t, a CO oxidation removing unit temperature detector 38, a CO shift unit temperature detector 55, and a temperature detector 65. The signal is input to the control unit 500. Further, the control unit 500 controls the valves 25a, 25b, 25d, 25e, 25f, 25h, 25k, 25m and the pumps 27a, 27b, 27c, 27d, 27m, 27k. The pumps 27a, 27b, 27c, 27d, 27m, and 27k function as a conveyance source.

  According to the present embodiment, when the temperature T11 of the CO shift unit 5 is low and lower than the activation temperature range thereof, the CO shift unit 5 is heated to maintain the CO shift unit 5 in the activation temperature range. Therefore, the control unit 500 works. The control unit 500 functions as a temperature adjusting unit that adjusts the temperature of the CO shift unit 5 and maintains the temperature of the CO shift unit 5 in the activation temperature range.

  The controller 500 controls the flow rate of air (oxygen-containing gas, oxygen component) supplied from the oxidation air passage 75 (oxygen supply unit) to the CO oxidation removal unit 37. Thereby, the temperature of the CO shift part 5 arrange | positioned upstream of the CO oxidation removal part 37 is controlled.

  Specifically, when the temperature T11 of the CO shift unit 5 is low and lower than the activation temperature range, the control unit 500 supplies the air (oxygen) supplied from the oxidation air passage 75 to the CO oxidation removal unit 37. The flow rate of the component, oxygen-containing gas) is controlled to increase. Thereby, the reaction in the CO oxidation removing unit 37 is promoted. Since this reaction is an oxidation reaction and is a reaction accompanied by heat generation, the amount of heat generated in the CO oxidation removal unit 37 increases. Accordingly, the amount of heat transferred from the relatively high temperature CO oxidation removal unit 37 to the relatively low temperature evaporation unit 36 is controlled. This is because, as shown in FIG. 1, the CO oxidation removal unit 37 and the evaporation unit 36 are adjacent to each other so as to exchange heat so that the CO oxidation removal unit 37 is located outside the evaporation unit 36.

  During normal operation of the reformer 2, the evaporation unit 36 evaporates the reformed water. Therefore, the evaporator 36 is generally maintained in a temperature range of about 100 ° C. due to the latent heat of evaporation of the reformed water. . And since the high temperature reformed gas which passed through the CO shift part 5 is supplied to the CO oxidation removal part 37 from the inlet 37i, the temperature of the CO oxidation removal part 37 becomes high. For this reason, the CO oxidation removal unit 37 is on the relatively high temperature side, and the evaporation unit 36 is on the relatively low temperature side. Therefore, the amount of heat that the CO oxidation removing unit 37 gives to the evaporation unit 36 increases. As a result, the amount of heat given to the reforming water in the evaporation section 36 increases. Therefore, vaporization is promoted in the evaporation section 36, the liquid phase moisture ratio is relatively decreased, and the gas phase moisture ratio is relatively increased.

  Here, in the heat exchanging section 4, the high-temperature reformed gas flowing through the second passage 4c and the mixed fluid flowing through the first passage 4a exchange heat with each other as described above. When the ratio of gas-phase moisture contained in the mixed fluid is relatively increased, the amount of latent heat of vaporization for vaporizing liquid-phase moisture is reduced, and the low-temperature gas is reduced from the reformed gas on the high temperature side. The amount of heat transferred to the mixed fluid on the side is reduced, and as a result, the temperature of the heat exchange unit 4 is relatively increased. Therefore, the temperature of the reformed gas heading toward the CO shift unit 5 through the second passage 4c of the heat exchange unit 4 relatively increases. Accordingly, the temperature T11 of the CO shift unit 5 is relatively increased.

  On the other hand, when the ratio of the liquid phase moisture contained in the mixed fluid flowing through the first passage 4a is relatively increased, the amount of latent heat of vaporization for vaporizing the liquid phase moisture is large. Thus, in the heat exchange unit 4, the amount of heat transferred from the reformed gas in the second passage 4c on the high temperature side to the mixed fluid in the first passage 4a on the low temperature side increases, and as a result, the temperature of the heat exchange unit 4 increases. Relatively decreases. Therefore, the temperature of the reformed gas toward the CO shift unit 5 through the second passage 4c of the heat exchange unit 4 relatively decreases. Accordingly, the temperature T11 of the CO shift unit 5 relatively decreases.

  Conversely, when the temperature T11 of the CO shift unit 5 is excessively high and exceeds the active temperature range, or even when the temperature is close to the upper limit of the active temperature range, the temperature T11 is controlled to be relatively lowered. Part 500 works. That is, when the temperature T11 of the CO shift unit 5 is excessively high, the control unit 500 controls the pump 27d to reduce the flow rate of the air supplied from the oxidation air passage 75 to the inlet 37i of the CO oxidation removal unit 37. . For this reason, the oxidation reaction in the CO oxidation removing unit 37 is suppressed, and the heat generation amount is suppressed. Accordingly, the amount of heat given to the evaporation unit 36 by the CO oxidation removing unit 37 is reduced. As a result, the amount of heat given to the reforming water in the evaporation section 36 is reduced. Therefore, in the evaporation part 36, the liquid-phase water ratio increases relatively, and the vapor-phase water ratio decreases relatively. In this case, in the heat exchanging unit 4, the amount of heat transferred from the high temperature side reformed gas flowing through the second passage 4c to the low temperature side mixed fluid flowing through the first passage 4a increases. As a result, the temperature of the heat exchange unit 4 is relatively lowered. Therefore, the temperature of the reformed gas that goes to the CO shift unit 5 via the heat exchange unit 4 is relatively lowered, and the temperature T11 of the CO shift unit 5 is relatively lowered.

  According to the above-described embodiment, when the temperature T11 of the CO shift unit 5 is low, the flow rate of the air (oxygen-containing gas) supplied from the oxidation air passage 75 to the CO oxidation removal unit 37 is increased, so that the CO The temperature T11 of the shift unit 5 rises, and the CO shift unit 5 is well maintained at a temperature suitable for the activation temperature range. When the temperature T11 of the CO shift unit 5 is high, the temperature T11 of the CO shift unit 5 is decreased by decreasing the flow rate of the air (oxygen-containing gas) supplied from the oxidation air passage 75 to the CO oxidation removal unit 37. In addition, the CO shift unit 5 is well maintained at a temperature suitable for the activation temperature range. In controlling the air flow rate, the conveying capacity of the pump 27d and / or the opening of the valve 25d in the oxidizing air passage 75 are controlled.

(The main part of an Example)
Now, according to the present embodiment, first, the control unit 500 constituting the diagnosis means first performs a gas leak diagnosis of the reformer 2, and then performs a gas leak diagnosis of the fuel cell. Leakage diagnosis is performed before the fuel cell system is shipped, immediately before the start of the fuel cell system, when pipes and parts are replaced after shipment, when pipes and parts are replaced after shipment, and when the fuel cell system is maintained. Is exemplified.

  At the time of gas leak diagnosis, the combustion unit 30 is not ignited and is maintained in a normal temperature region or less than 400 ° C. (a temperature region in which coking does not occur in the reforming unit).

  In the gas leak diagnosis, the control unit 500 supplies the raw fuel to a region upstream from the reforming unit 34 without reforming the gaseous raw fuel (city gas mainly composed of methane), and Is supplied to the reforming unit 34 and, in turn, is supplied to the passage downstream of the reforming unit 34, and the gas leakage of the reforming apparatus 2 is diagnosed. That is, the control unit 500 opens the valves 25a and 25b and closes the valve 25e (first cutoff valve) and the valve 25f. By closing the valves 25e and 25f, the communication between the reformer 2 and the anode 11 of the fuel cell 1 is blocked. In this state, the controller 500 drives the pump 27b (raw fuel conveyance source). Thus, the gaseous raw fuel is supplied to the inlet 4i of the heat exchange unit 4 (upstream of the reforming unit 4) via the desulfurizer 62x and the fuel passage 62. In this case, other valves such as the valves 25k, 25d, 25f, 25m, and 25h are closed.

  As described above, by driving the pump 27b, the gaseous raw fuel flows into the first passage 4a of the heat exchange section 4 and the outer passage 34p of the reforming section 34, flows in the direction of the arrow A1, and passes through the turn-up section 34m. It flows into the passage 34i, flows in the direction of the arrow A2, further flows into the second passage 4c of the heat exchanging section 4, and flows into the CO shift section 5 from the inlet 5i of the CO shift section 5 through the warm-up section 47. . Further, the gaseous raw fuel passes through the inside of the CO shift unit 5, flows from the outlet 5p of the CO shift unit 5 through the purification passage 400 in the direction of the arrow W2, and reaches the second merge region M2. In this case, the pump 27d as an air conveyance source is stopped and the air supply valve 25d is closed, so that the gaseous raw fuel is not mixed with air.

  Further, the gaseous raw fuel flows into the CO oxidation removal unit 37 from the inlet 37i, and flows into the anode gas passage 100 side from the outlet 37p of the CO oxidation removal unit 37. In this case, the valve 25e (first cutoff valve) is closed, and the valve 25f (second cutoff valve) and the valve 25h (third cutoff valve) are closed. When the pressure of the pressure sensor 100x provided in the anode gas passage 100 becomes higher than a predetermined value Pr (for example, gauge pressure: 5 to 40 kPa, 20 kPa), the pump 27b is stopped, and the valves 25a and 25b (reforming unit) are stopped. The valve upstream of 34) is closed. At this time, the valve 25e (the valve downstream of the reforming unit 34) is closed. As a result, the space from the valve 25b to the valve 25e in the passage through which the gaseous raw fuel flows from the fuel supply source 61 as described above is essentially a sealed space. The pressure sensor 100x does not detect a decrease in gas pressure unless a gas leak occurs in this sealed space for a predetermined time (for example, 1 minute to 10 minutes, 5 minutes).

  According to such a present Example, the gas leak in the reforming part 34 of the reformer 2 is diagnosed. Further, at the time of diagnosis, gas leakage is diagnosed in a region upstream of the reforming unit 34 in the passage through which the raw fuel flows, that is, the fuel passage 62 and the first passage 4a of the heat exchange unit 4. Further, at the time of diagnosis, in the passage through which the raw fuel flows, the gas in the region downstream of the reforming unit 34, that is, the second passage 4c, the CO shift unit 5, the purification passage 400, and the CO oxidation removal unit 37 of the heat exchange unit 4. A leak is diagnosed. Furthermore, gas leakage in the anode gas passage 100 in the upstream passage portion 100u from the valve 25e (first shutoff valve) and in the bypass passage 150 in the upstream passage portion 150u from the valve 25h (third shutoff valve) is diagnosed. The

  As long as no pressure drop occurs in a predetermined time (for example, 1 to 10 minutes, 5 minutes) in the above-described sealed space, no gas leakage occurs in the reformer 2, and the reformer 2 is normal. .

  On the other hand, when the pressure sensor 100x detects a decrease in gas pressure, the control unit 500 determines that a gas leak has occurred in the reformer 2. The controller 500 repeats the above-described leak diagnosis a plurality of times, and outputs a gas leak determination signal to the fuel cell system when a gas leak is detected a predetermined number of times or more. In this way, according to the present embodiment, in the reformer 2, there is a high risk of gas leakage in any of the region upstream of the reforming unit 34, the reforming unit 34, and the region downstream of the reforming unit 34. Is determined.

  As described above, the gas leakage diagnosis of the reformer 2 is performed, and if there is no gas leakage and is normal, the control unit 500 subsequently performs the gas leakage diagnosis of the fuel cell 1. In this case, the controller 500 opens the valve 25e (first cutoff valve) while the valve 25f (second cutoff valve) and the valve 25h (third cutoff valve) are closed. Thereby, the reformer 2 and the anode 11 of the fuel cell 1 communicate with each other. In this state, the controller 500 drives the pump 27b as necessary. Then, the raw fuel is supplied to the anode 11 from the inlet 11i of the fuel cell 1 through the anode gas passage 100 and the valve 25e. When the pressure P1 of the pressure sensor provided in the anode gas passage 100 becomes higher than a predetermined value Pc (for example, 10 kPa, Pc≈Pr or Pc = Pr), the pump 27b is stopped.

  In this case, as long as there is no gas leakage, the entire anode gas passage 100, the space of the anode electrode 11 of the fuel cell 1, and the passage portion 100u between the fuel cell 1 and the valve 25f in the off-gas passage 110 are sealed spaces. ing. That is, in this sealed space, the pressure sensor 100x does not detect a decrease in the gas pressure of the fuel cell 1 unless a gas leak occurs in a predetermined time (for example, 1 minute to 10 minutes, 5 minutes). It is determined that there is no leak.

  If a gas leak occurs in a predetermined time (for example, 1 minute to 10 minutes, 5 minutes), the pressure sensor 100x detects a decrease in the gas pressure of the fuel cell 1, so that the gas leak of the anode 11 of the fuel cell 1 occurs. It is determined that there is a high risk.

  As described above, the gas leak of the fuel cell 1 is diagnosed following the diagnosis of the gas leak in the reformer 2. If there is no gas leakage from the fuel cell 1, the valve 25 h and the valve 25 f are opened, so that the raw fuel is supplied to the combustion unit 30 of the reformer 2 via the off-gas passage 110 and the bypass passage 150 and is released to the outside air.

  When the raw fuel is supplied to the combustion unit 30 through the off-gas passage 110 and the bypass passage 150 along with the end of the gas leak diagnosis described above, the control unit 500 drives the pump 27c as an air carrier source for dilution. Is supplied to the combustion unit 30 and the raw fuel is diluted with air. Therefore, the raw fuel is discharged from the combustion unit 30 and the combustion exhaust gas passage 250 to the outside air in a state diluted with air. With the completion of the above-described gas leak diagnosis, most of the raw fuel is discharged to the combustion unit 30 side. As a result, the space of the reformer 2 and the space of the anode electrode 11 of the fuel cell 1 are not pressurized and become 0 at the gauge pressure. Therefore, a certain amount of gaseous raw fuel (approximately equivalent to atmospheric pressure) remains in the space of the reformer 2.

  As described above, according to this embodiment, a gas leakage diagnosis in the reformer 2 can be performed. In particular, in the reformer 2, gas leakage in a region upstream of the reforming unit 34, that is, the fuel channel 62 and the first passage 4 a of the heat exchange unit 4 in the path through which the raw fuel flows is diagnosed. Furthermore, as shown in FIG. 4, in the passage through which the raw fuel flows, the region downstream of the reforming unit 34, that is, the second passage 4 c of the heat exchange unit 4, the CO shift unit 5, the purification passage 400, and CO oxidation removal Gas leakage in the part 37 is diagnosed. Furthermore, according to the present embodiment, it is possible to perform gas leakage diagnosis in the anode gas passage 100 and the anode electrode 11 of the fuel cell 1.

  Incidentally, in the power generation operation of the fuel cell 1, the region downstream of the reforming unit 34, that is, the second passage 4 c, the CO shift unit 5, the purification passage 400, and the CO oxidation removal unit 37 of the heat exchange unit 4 are modified. Although the reformed gas mainly containing hydrogen generated in the mass part 34 flows, hydrocarbon-based or alcohol-based raw fuel does not flow.

  In this regard, according to the present embodiment, a system for diagnosing gas leakage of the reformer 2 and the fuel cell 1 by using the gaseous raw fuel before generating the hydrogen-rich reformed gas is adopted. . In this embodiment, unlike a method for diagnosing gas leakage with an inert gas such as nitrogen gas, a tank dedicated to gas leakage diagnosis for storing inert gas such as nitrogen gas and helium gas is not required. This is advantageous in suppressing the complexity and size of equipment. For this reason, it is suppressed that inert gas, such as nitrogen gas used for the gas leak diagnosis, remains in the reformer 2.

  If an inert gas such as nitrogen gas used for the gas leak diagnosis remains in the reformer 2, the nitrogen remaining in the reformer 2 when the reformer 2 is started next time. An inert gas such as a gas is supplied to the combustion unit 30, and there is a fear that the burning combustion unit 30 is blown off (fire extinguishing). In this regard, according to the present embodiment, it is possible to prevent an inert gas such as nitrogen gas from remaining in the reformer 2. For this reason, when the reformer 2 is started up next time, it is possible to suppress the inactive gas such as nitrogen gas remaining in the reformer 2 from extinguishing the combustion unit 30.

Further, when the reformer 2 is started after the gas leak diagnosis, the blow-off of combustion in the combustion unit 30 is suppressed as in the following (i) and (ii). Therefore, the system stop caused by blow-off is prevented.
(I) When the first shut-off valve (valve 25e) is opened when the reforming raw material is charged after steam generation in the reformer 2, the fluid filled in the reformer 2 and the fuel cell 1 is raw fuel. is there. Raw fuel is flammable. Accordingly, when the reformer 2 is started up next time, even if the raw fuel remaining in the reformer 2 is supplied to the combustion unit 30 of the reformer 2, the raw fuel is inflammable and thus inactive. Unlike gas, the blow-off of combustion in the combustion part 30 is suppressed.
(Ii) When the second shut-off valve (valve 25f) and the third shut-off valve (valve 25h) are opened and the first shut-off valve (valve 25e) is closed immediately before the start of power generation in the fuel cell, the reformer 2 and the fuel cell Since the fuel filled in 1 is a combustible raw fuel, when it is supplied from the combustor 30, it becomes the fuel in the combustor 30. Therefore, unlike the inert gas, the blow-off of combustion in the combustion unit 30 is suppressed.

  In addition, according to the present embodiment, at the time of diagnosis, since the diagnosis is performed without reforming the raw fuel, the combustion unit 30 may not be burned. As described above, since the reforming unit 34 is performed in a room temperature state where the reforming unit 34 is not heated, coking in the reforming unit 34 is also suppressed. Note that when raw fuel is supplied to the high-temperature reforming section 34, coking (carbon generation) may occur in the catalyst 34e of the reforming section 34.

  Further, the raw fuel containing the sulfur component may be a poisoning substance for the reforming unit 34 and the fuel cell 1. In this regard, according to this embodiment, the gaseous raw fuel that has been desulfurized and purified by the desulfurizer 62x is used, so the catalyst and fuel of the reforming section 34 and the fuel cell 1, in particular the reformer 2, are used. Influencing the catalyst of the battery 1 is suppressed.

  Further, when the time has not passed since the previous power generation operation of the fuel cell system, the reforming unit 34 may still be at a high temperature. As described above, coking (carbon generation) may occur in the catalyst 34e of the reforming unit 34 when the raw fuel is supplied to the reforming unit 34 having a high temperature (for example, 400 ° C. or higher) without supplying moisture. . Therefore, according to this embodiment, when a predetermined time (for example, 1 hour) has not elapsed since the end of the power generation operation of the previous fuel cell system, or the temperature T1 of the reforming unit 34 is equal to or higher than the predetermined temperature (for example, 400 ° C.). If so, the control unit 500 is set not to execute the gas leakage diagnosis described above. This suppresses coking.

  According to the present embodiment, when a gas leak is not detected in the leak diagnosis, it can be performed as follows. That is, when the reforming operation of the reforming device 2 and the power generation operation of the fuel cell 1 are not performed after the gas leak diagnosis, the reforming device 2 and the gaseous raw fuel for gas leak diagnosis are not released to the outside air. The fuel cell 1 may be sealed as it is. In addition, after the residual gas remaining in the reformer 2 and the fuel cell 1 is purged with the purge gas, a purge process is performed in which the purge gas is sealed in the reformer 2 and the fuel cell 1. As described above, the control unit 500 can also execute the gas leakage diagnosis in the purge process.

  FIG. 5 shows a second embodiment. Since the present embodiment basically has the same configuration and effects as the first embodiment, FIGS. 1 to 4 are applied mutatis mutandis. Hereinafter, a description will be given focusing on portions different from the first embodiment. Also in the present embodiment, the combustion section 30 is not ignited at the time of gas leak diagnosis, and is maintained in the normal temperature range or 400 ° C. or lower (the temperature range where coking does not occur in the reforming section). In this embodiment, every time the reformer 2 of the fuel cell system is started and before the start, the gas leak diagnosis of the reformer 2 and the gas leak diagnosis of the fuel cell 1 are performed simultaneously. In this case, the control unit 500 supplies the raw fuel to a region upstream of the reforming unit 34 without reforming the gaseous raw fuel, and further supplies the raw fuel to the reforming unit 34. As a result, it supplies to the channel | path downstream of the reforming part 34, and also supplies it to the anode electrode 11 of the fuel cell 1, and diagnoses the gas leak of the reformer 2 and the fuel cell 1. FIG.

  FIG. 5 shows a flowchart executed by the control unit 500 in the gas leak diagnosis executed before starting the fuel cell system. When the diagnostic switch 507 is operated by the operator, the control of this flowchart is started. As shown in FIG. 5, the valves 25a, 25b, and 25e are opened, and the valves 25h and 25f are closed (step S2). The reformer 2 and the anode 11 of the fuel cell 1 communicate with each other by opening the valve 25e.

  After driving the pump 27b (step S4), the controller 500 determines whether or not the pressure P1 of the pressure sensor 100x is greater than a first threshold pressure Pr (for example, 20 kPa as a gauge pressure) (step S6). When the pressure P1 is smaller than the first threshold pressure Pr (NO in step S6), the pump 27b is continuously driven. If the pressure P1 does not become higher than the first threshold pressure Pr within a predetermined time (for example, a value of 20 seconds) (YES in Step S8), the control unit 500 outputs an abnormal stop command (Step S10).

  When the pressure P1 is higher than the first threshold pressure Pr (YES in step S6), the control unit 500 stops the pump 27b and closes the valves 25a and 25b on the inlet side of the reformer 2 to provide a sealed space. Is formed (step S12). In the closed state, the controller 500 waits for a predetermined time (for example, 5 minutes) (step S14). Thereafter, the controller 500 determines whether or not the pressure P1 of the pressure sensor 100x is higher than a second threshold pressure Pe (for example, 19 kPa as a gauge pressure) (step S16). If the pressure P1 is lower than the second threshold pressure Pe (for example, 19 kPa as a gauge pressure) (NO in step S16), the risk of gas leakage is high, so the counter is incremented by 1 (step S36). If the number of counters exceeds n (for example, 3 times) (YES in step S38), the fuel cell system is abnormally stopped (step S40). If the number of counters does not exceed n times (for example, 3 times) (NO in step S38), the process returns to step S2 to perform the leakage diagnosis again.

  As a result of the determination in step S16, if the pressure P1 of the pressure sensor 100x is higher than the second threshold pressure Pe (eg, 19 kPa in gauge pressure) (YES in step S16), it is determined that there is no pressure leak and is normal, and normal A signal is output (step S18). Next, the controller 500 opens the valve 25f and the valve 25h (step S20). As a result, the raw fuel supplied to the inside of the fuel cell 1 and the reformer 2 is discharged from the combustion unit 30 to the outside air via the offgas passage 100 and the bypass passage 150. In this case, the controller 500 can dilute the raw fuel with air by driving the pump 27c and supplying air to the combustor 30 as necessary. In this case, the influence on the outside air is reduced.

  Next, it is determined whether or not the pressure P1 of the pressure sensor 100x has decreased to near atmospheric pressure. That is, it is determined whether or not the pressure P1 is lower than a third threshold pressure Pd (for example, 2 kPa in gauge pressure) (step S22). If the pressure P1 is lower than a third threshold pressure Pd (for example, 2 kPa as a gauge pressure) (YES in step S22), since most of the raw fuel is released to the outside air, the valve 25f and the valve 25h are closed. (Step S30), the process proceeds to the activation sequence of the fuel cell 1 (Step S26). As a result of the determination in step S22, if the pressure P1 of the pressure sensor 100x is higher than the third threshold pressure Pd (for example, 2 kPa in gauge pressure) (NO in step S22), the raw fuel is still sufficiently discharged to the outside air. is not. Therefore, even if a predetermined time (for example, 10 seconds) has elapsed (YES in step S28), if the pressure P1 of the pressure sensor 100x is higher than the third threshold pressure Pd (for example, 2 kPa in gauge pressure) (YES in step S28). The control unit 500 estimates that at least one of the discharge valve 25f and the valve 25h, or both the valves 25a and 25b are broken, and closes the valve 25f and the valve 25h. A command to close 25b is output (step S30), and a signal for abnormally stopping the fuel cell system is output (step S32). Steps S22 and S28 function as failure determination means for determining failure of the valves 25f and 25h.

  When the above-described flowchart shown in FIG. 5 is executed, the gas leak diagnosis is simultaneously performed on both the reformer 2 and the anode 11 of the fuel cell 1. If a gas leak diagnosis is performed on both the reformer 2 and the anode 11 of the fuel cell 1, when a gas leak is detected, the valve 25e and the valve 25h are closed to close the reformer 2 and In a state where communication with the fuel cell 1 is cut off, the raw fuel is supplied again to the reformer 2 by the pump 27b and rediagnosed. If no gas leak is diagnosed in the rediagnosis, no gas leak has occurred in the reformer 2, and there is a high possibility that a gas leak has occurred in the region downstream of the valve 25e (the fuel cell 1 side). Determined. When a gas leak is diagnosed in the rediagnosis, it is determined that at least the gas leak has occurred in the reformer 2. The gas leak diagnosis according to the flowchart shown in FIG. 5 is executed every time the start switch 504 is operated and the reformer 2 is started.

  FIG. 6 shows a flowchart executed by the control unit 500 in the gas leak diagnosis executed after the shipment of the fuel cell system (when the passage is changed or when the parts are changed). When the diagnosis switch 507 is operated, the control of this flowchart is started. As shown in FIG. 6, the valves 25a, 25b, and 25e are opened, and the valves 25h and 25f are closed (step SB2). Next, the controller 500 drives the pump 27b (step SB4). Thereafter, the controller 500 determines whether or not the pressure P1 of the pressure sensor 100x is greater than a first threshold pressure Pr (for example, 20 kPa as a gauge pressure) (step SB6). As a result of the determination in step SB6, even if a predetermined time (for example, 20 seconds) elapses, the pressure P1 of the pressure sensor 100x does not become higher than the first threshold pressure Pr (for example, 20 kPa in gauge pressure) (step SB8). YES), an abnormal signal is output (step SB10). When the pressure P1 is greater than the first threshold pressure Pr (YES in step SB6), the control unit 500 stops the pump 27b and closes the valves 25a and 25b on the inlet side of the reformer 2 to provide a sealed space. Is formed (step SB12).

  In a state where the sealed space is formed, the control unit 500 waits for a predetermined time (for example, 10 minutes) (step SB14). Thereafter, the controller 500 determines whether or not the pressure drop of the pressure P1 of the pressure sensor 100x is smaller than a threshold value (for example, 0.2 kPa in gauge pressure) (step SB16). If the pressure drop of the pressure P1 is larger than a threshold value (for example, 0.2 kPa in gauge pressure) (NO in step SB16), the control unit 500 has a pressure leak in the reformer 2 or the fuel cell 1, It is determined that there is an abnormality, and an abnormality signal is output (step SB10).

  If the result of determination in step SB16 is that the pressure drop in pressure P1 is smaller than a threshold value (for example, 0.2 kPa in gauge pressure) (YES in step SB16), control unit 500 causes reformer 2 and fuel cell 1 to It is determined that there is no pressure leak and is normal, and a normal signal is output (step SB18).

  Next, the control unit 500 opens the valves 25f and 25h (step SB20), and supplies the gaseous raw fuel in the sealed space to the combustion unit 30 of the reformer 2 via the off-gas passage 110 and the bypass passage 150. Since the combustion unit 30 communicates with the outside air through the combustion exhaust gas passage 250, the raw fuel is released to the outside air. In this case, as necessary, the controller 500 may drive the pump 27c, which is an air conveyance source, to supply air to the combustor 30 and dilute the raw fuel with air. Next, it is determined whether or not the detected pressure of the pressure P1 of the pressure sensor 100x is within a threshold value (for example, 0 to 1 kPa as a gauge pressure) (step SB22). If the detected pressure of the pressure P1 is within a threshold value (for example, 0 to 1 kPa as a gauge pressure), most of the raw fuel is released to the outside air, so the control unit 500 closes the valves 25f and 25h ( Step SB24), the process proceeds to the activation sequence (step SB26).

  If the result of determination in step SB22 is that the detected pressure of the pressure P1 of the pressure sensor 100x does not fall within a threshold value (for example, 0 to 1 kPa in gauge pressure) even after a predetermined time has elapsed (YES in step SB28), the valve It is determined that the decrease in gas pressure is small despite the 25f and 25h opening commands being output (YES in step SB28). Therefore, even if a predetermined time (for example, 10 seconds) elapses, the pressure P1 of the pressure sensor 100x does not fall within a threshold value (for example, 0 to 1 kPa in gauge pressure) (YES in Step SB30), that is, the pressure sensor 100x. If the detected pressure of the pressure P1 is not close to the atmospheric pressure, it is estimated that at least one of the valve 25f and the valve 25h or both the valves 25a and 25b are broken. Therefore, the controller 500 outputs a command to close the valves 25f and 25h, a command to close the valves 25a and 25b (step SB30), and outputs a defective valve replacement command (step SB32). Steps SB28 and SB30 function as a failure determination unit that determines a failure of the valves 25f and 25h or a failure of the valves 25a and 25b.

  When the above-described flowchart shown in FIG. 6 is executed, gas leakage diagnosis is performed simultaneously on both the reformer 2 and the anode 11 of the fuel cell 1. If a gas leak diagnosis is performed on both the reformer 2 and the anode 11 of the fuel cell 1, when a gas leak is detected, the valve 25e and the valve 25h are closed to close the reformer 2 and In a state where communication with the fuel cell 1 is cut off, the raw fuel is supplied again to the reformer 2 by the pump 27b, and re-diagnosis is executed. If no gas leak is diagnosed in the rediagnosis, no gas leak has occurred in the reformer 2, and there is a high possibility that a gas leak has occurred in the region downstream of the valve 25e (the fuel cell 1 side). Determined. In the re-diagnosis described above, if a gas leak is diagnosed, it is determined that at least the gas leakage has occurred in the reformer 2.

  Since the third embodiment basically has the same configuration and operation effect as the first embodiment, FIGS. 1 to 4 are applied mutatis mutandis. Hereinafter, a description will be given centering on differences from the first embodiment. According to the present embodiment, as described above, when the time has not passed since the end of the power generation operation of the previous fuel cell system, the reforming unit 34 may still be at a high temperature. If the raw fuel is supplied to the reforming section 34 at a high temperature (for example, 450 ° C. or higher) without supplying moisture, coking (carbon generation) may occur in the catalyst 34e of the reforming section 34.

  Therefore, according to the present embodiment, the control unit 500 having a timer function determines whether or not a predetermined time (for example, 1 hour) has elapsed since the end of the power generation operation of the previous fuel cell system, or the temperature of the reforming unit 34. It is determined whether or not T1 is still high and is equal to or higher than a predetermined temperature (for example, 400 ° C.). Then, when the predetermined time (for example, 1 hour) has not elapsed since the end of the power generation operation of the previous fuel cell system, or the temperature T1 of the reforming unit 34 is still high and is above the predetermined temperature (for example, 400 ° C.). In some cases, the control unit 500 does not perform the gas leakage diagnosis for supplying the raw fuel described above to the reformer 2. This suppresses coking.

  On the other hand, when a predetermined time (for example, 4 hours) has elapsed since the end of the power generation operation of the previous fuel cell system, or the temperature T1 of the reforming unit 34 becomes low and is less than the predetermined temperature (for example, 400 ° C.). When this is, since the occurrence of coking is suppressed, the control unit 500 performs a gas leak diagnosis for supplying the raw fuel described above to the reformer 2. At the time of gas leak diagnosis, water is not supplied from the evaporation unit 36 to the reforming unit 34.

  Since the fourth embodiment has basically the same configuration and operational effects as the first embodiment, FIGS. 1 to 4 are applied mutatis mutandis. Hereinafter, a description will be given centering on differences from the first embodiment. As described above, when the time has not passed since the end of the power generation operation of the previous fuel cell system, the reforming unit 34 may still be at a high temperature. As described above, when raw fuel is supplied to the high-temperature reforming section 34 at the time of gas leak diagnosis, coking (carbon generation) may occur in the catalyst 34e of the reforming section 34.

  Therefore, according to the present embodiment, when the reformer 2 of the fuel cell system is started for the first time after diagnosis, the S / C value is set higher than during normal startup or during power generation operation. For example, the value of S / C is about 3.0 to 3.3 at the time of normal startup of the reformer 2 or during normal power generation operation.

  However, according to the present embodiment, when the reformer 2 of the fuel cell system is started for the first time after diagnosis, the controller 500 sets the S / C value to 5 or more, 7 or more, or 9 or more (the upper limit is 14). To the extent possible). Specifically, the value of S / C is set to about 5 to 13, for example, about 6 to 10. As a result, when the reformer 2 of the fuel cell system is started for the first time after diagnosis, it becomes rich in water and coking (carbon) in the catalyst 34e of the reforming section 34 is suppressed.

Here, the value of S / C relates to the ratio of reformed water and raw fuel. The value of S / C is (number of moles of H ₂ O contained in reforming water supplied to reformer ₂ ) / (carbon component contained in raw fuel for reforming supplied to reformer 2) Number of moles). The value of S / C corresponds to the amount of H ₂ O supplied to the reforming unit 34 via the evaporation unit 36. Here, when the flow rate of the reforming water supplied to the evaporation unit 36 is insufficient and the value of S / C is not appropriate, there is a possibility that coking in which carbon precipitates may occur in the reforming unit 34 or the like. Absent.

  Since the fifth embodiment basically has the same configuration and operational effects as the first embodiment, FIGS. 1 to 4 are applied mutatis mutandis. Also in the present embodiment, the combustion section 30 is not ignited at the time of gas leak diagnosis, and is maintained in a normal temperature range or less than 400 ° C. (a temperature range in which coking does not occur in the reforming section). The control unit 500 that constitutes the diagnostic means, at the end of the gas leakage diagnosis, combusts after the diagnosis of the gas discharged from the region downstream of the reformer 2 or the outlet 11p of the anode 11 of the fuel cell 1. The raw fuel is supplied to the combustion unit 30. At this time, the control unit 500 ignites the igniter of the combustion unit 30. The raw fuel thereby is burned in the combustion unit 30. Combustion air can be supplied to the combustion unit 30 by driving the pump 27c as necessary.

  FIG. 7 shows a sixth embodiment. Since this embodiment has basically the same configuration and effects as the first embodiment, FIGS. 3 and 4 are applied mutatis mutandis. Hereinafter, a description will be given centering on differences from the first embodiment. As shown in FIG. 7, a communication path 460 is provided to connect the fuel supply source 61 and the inlet 11 i of the anode electrode 11 of the fuel cell 1 so as to bypass the reforming unit 34, that is, without passing through the reforming unit 34. ing. One end 460a of the communication path 460 is connected to the fuel supply source 61 side, that is, upstream of the valve 25b. The other end 460 c of the communication path 460 is connected to the anode electrode 11 of the fuel cell 1 through the valve 403. The communication path 460 is connected to the valve 403 and the pressure sensor 100y (pressure detection means). At the time of leak diagnosis, the control unit 500 drives the pump 27b with the valve 403 opened. As a result, the gaseous raw fuel bypasses the reforming section 34 of the reforming apparatus 2, that is, does not pass through the reforming section 34 of the reforming apparatus 2, and passes through the communication path 460 and the valve 403 to the fuel cell 1. To the anode electrode 11. In this case, since the valve 25 e and the valve 25 f are closed, the raw fuel is sealed in the anode electrode 11 of the fuel cell 1.

  When the detected pressure of the pressure sensor 100y reaches the threshold pressure, the valve 403 is closed while the valves 25f and 25e are closed, and the pump 27b is stopped. Wait for a predetermined time in this state. When the decrease in the detection pressure of the pressure sensor 100y exceeds the threshold pressure, it is determined that there is a high possibility that gas leakage has occurred in the anode electrode 11 of the fuel cell 1. If the decrease in the detection pressure of the pressure sensor 100y is smaller than the threshold pressure, it is determined that no gas leakage has occurred in the anode 11 of the fuel cell 1.

  At the time of such diagnosis, since the control unit 500 closes the valve 25b, even if the pump 27b is driven, the raw fuel bypasses the reformer 2, and the raw fuel is supplied to the reformer 2. Therefore, the leakage diagnosis of the reformer 2 is not performed.

  By the way, when hydrogen gas remains in the reforming section 34, a gas leak diagnosis is performed, and when the raw fuel is supplied to the reforming device 2, the remaining hydrogen gas is pushed out to the raw fuel and is not in a power generation operation. Nevertheless, the fuel cell 1 may be supplied to the anode electrode 11 and stay there. In this regard, according to this embodiment, when the gas leak diagnosis of the fuel cell 1 is performed, the raw fuel is supplied to the anode 11 of the fuel cell 1 without passing through the reforming unit 34. For this reason, even when hydrogen gas remains in the reforming unit 34, the hydrogen gas is not supplied to the anode electrode 11 of the fuel cell 1 and is prevented from staying in the anode electrode 11.

  FIG. 8 shows a seventh embodiment. Since the present embodiment basically has the same configuration and effect as the first embodiment, FIGS. 3 and 4 are applied mutatis mutandis. Also in the present embodiment, the combustion section 30 is not ignited at the time of gas leak diagnosis, and is maintained in a normal temperature range or less than 400 ° C. (a temperature range in which coking does not occur in the reforming section). Hereinafter, a description will be given centering on differences from the first embodiment. A gas sensor 100w (raw fuel detection means) is provided outside the reformer 2, the fuel cell 1, the anode gas passage 100, and the bypass passage 150. The gas sensor 100w is a sensor that detects a substance (component) contained in the raw fuel, and can be detected by a change in electrical resistance, a change in physical quantity of capacitance, or the like caused by the adhesion of the substance. A signal from the gas sensor 100 w is input to the control unit 500. The control unit 500 diagnoses a gas leak by detecting a substance contained in the raw fuel by the gas sensor 100w. The pressure sensor 100x may be mounted or abolished.

(Other)
The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist. In the above-described embodiment, as shown in FIG. 1, the pressure sensor 100 x is disposed in the branch region between the bypass passage 150 and the anode gas passage 100, but the present invention is not limited to this, and the anode gas passage other than the branch region. 100 may be provided. Furthermore, the pressure sensor 100x may be provided on the outlet 37p side of the CO oxidation removing unit 37. The evaporation unit 36 and the CO oxidation removal unit 37 are integrated with the reforming unit 34, but may be separated from the reforming unit 34 in terms of distance. The CO shift unit 5 may be separated from the reforming unit 34 in terms of distance. The following technical idea can also be grasped from the above description.
[Additional Item 1] A reformer having a reformer that generates a reformed fluid containing an active material by reforming raw fuel, and the reformer reformed by the reformer of the reformer. A fuel cell that performs a power generation reaction based on a solid fluid and an oxidant fluid, a fluid passage that communicates the reforming unit of the reformer and the fuel cell, and supplies the reformed fluid to the fuel cell; Diagnostic means for diagnosing leakage of raw fuel, and the diagnostic means serves as both a leakage diagnostic fluid and an enclosing fluid without reforming the raw fuel, and the reformer and / or the Supplying to a fluid passage, and diagnosing leakage of the raw fuel in at least a region downstream of the reforming portion of the reformer and the fluid passage, and if there is no leakage, feed raw fuel to at least the reformer. Fuel characterized by being sealed Pond system.
[Additional Item 2] A reformer having a reforming unit that generates a reformed fluid containing an active material by reforming raw fuel, and a reformed fluid and an oxidant fluid reformed by the reformer A fuel cell that performs a power generation reaction based on the above, a fluid passage that communicates the reforming unit of the reformer with the fuel cell, and supplies the reformed fluid to the fuel cell, and diagnoses leakage of raw fuel The diagnostic means supplies the fuel cell to the fuel cell as a leakage diagnosis fluid and an enclosure fluid without reforming the raw fuel, and the raw fuel in the fuel cell is not modified. A fuel cell system characterized by diagnosing a fuel leak and enclosing the raw fuel in the fuel cell if there is no leak.

  The present invention can be used in, for example, fuel cell systems for vehicles, stationary devices, electronic devices, electric devices, and portable devices.

1 is a system diagram of a fuel cell system according to Embodiment 1 having a reformer and a fuel cell. FIG. FIG. 4 is an enlarged view of the vicinity of the reformer according to the first embodiment. It is a block diagram which shows typically the relationship of a control part. FIG. 3 is a diagram schematically illustrating a passage relationship of the fuel cell system according to the first embodiment. 10 is a flowchart executed by a control unit according to the second embodiment. 10 is another flowchart according to the second embodiment and executed by the control unit. FIG. 10 is a system diagram of a fuel cell system according to Embodiment 6 and including a reformer and a fuel cell. FIG. 10 is a system diagram of a fuel cell system according to Embodiment 7 and including a reformer and a fuel cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 is a fuel cell, 2 is a reformer, 30 is a combustion part, 31 is a heat insulation part, 34 is a reforming part, 36 is an evaporation part, 37 is a CO oxidation removal part (CO reduction part), 4 is a heat exchange part, 5 is a CO shift section, 62 is a fuel path, 72 is an air path (oxygen supply section), 81 is a water tank, 82 is a reforming water path (reforming water supply section), 100 is an anode gas path, and 200 is a cathode gas. Passage, 300 is a water vapor passage, 400 is a purification passage, 500 is a control section (diagnostic means), 31t is a reforming section temperature detector, 38 is a CO oxidation removal section temperature detector, 55 is a CO shift section temperature detector, 65 Indicates a temperature detector, and 100x indicates a pressure sensor (pressure detection means).

Claims (12)

A reformer having a reforming unit that generates a reformed fluid containing an active material by reforming raw fuel; and
A fuel cell that performs a power generation reaction based on the reformed fluid and the oxidant fluid reformed in the reforming unit of the reformer;
A fluid passage for communicating the reforming unit of the reformer and the fuel cell and supplying the reformed fluid to the fuel cell;
Diagnostic means for diagnosing leakage of the raw fuel,
The diagnostic means supplies the raw fuel to the reforming device and / or the fluid passage without reforming the raw fuel, and at least the region in the downstream of the reforming portion of the reforming device and the fluid passage. A fuel cell system for diagnosing leakage of raw fuel.   The pressure detection means is provided in a region downstream or upstream of the reforming unit according to claim 1, and the diagnosis means diagnoses the leakage of the raw fuel based on a pressure drop by the pressure detection means. A fuel cell system.   3. The raw fuel detection means is provided outside the reformer and the fluid passage according to claim 1, wherein the diagnosis means is based on detection of a substance contained in the raw fuel by the raw fuel detection means. A fuel cell system for diagnosing leakage of the raw fuel. A reformer having a reforming unit that generates a reformed fluid containing an active material by reforming raw fuel; and
A fuel cell that performs a power generation reaction based on the reformed fluid and the oxidant fluid reformed by the reformer;
A fluid passage for communicating the reforming unit of the reformer and the fuel cell and supplying the reformed fluid to the fuel cell;
Diagnostic means for diagnosing raw fuel leaks,
The diagnostic means supplies the raw fuel to the fuel cell without reforming the raw fuel, and diagnoses the leakage of the raw fuel in the fuel cell.   5. The desulfurizer for desulfurizing the raw fuel is provided in the fuel cell system according to claim 1, and the raw fuel that has passed through the desulfurizer is used for leak diagnosis. Fuel cell system.   The fuel cell system according to claim 1, wherein the fluid passage includes a CO reduction unit that reduces carbon monoxide contained in the reformed fluid. 7. The anode gas passage according to claim 1, wherein the fluid passage is provided between the reformer and the fuel cell, and supplies the raw fuel to an inlet of an anode electrode of the fuel cell. An off-gas passage extending from an outlet of the anode electrode of the fuel cell, a first shut-off valve capable of shutting off the raw fuel from the anode gas passage toward the inlet of the anode electrode of the fuel cell, and the fuel A second shut-off valve capable of shutting off the raw fuel from the outlet of the anode electrode of the battery toward the off-gas passage,
The diagnostic means (i) performs a first diagnosis of leakage in a region downstream of the reforming unit of the reformer in a state where the first shut-off valve is closed so that the raw fuel is not supplied to the fuel cell. And (ii) closing the second shut-off valve and opening the first shut-off valve to supply the raw fuel to the anode electrode of the fuel cell, A fuel cell system for diagnosing leakage. 7. The anode gas passage according to claim 1, wherein the fluid passage is provided between the reformer and the fuel cell and supplies the raw fuel to an inlet of the anode electrode of the fuel cell. An off-gas passage extending from an outlet of the anode electrode of the fuel cell, a bypass passage that bypasses the fuel cell and connects the anode gas passage and the off-gas passage, and from the anode gas passage to the fuel cell A first shut-off valve capable of shutting off the raw fuel toward the anode electrode inlet, a second shut-off valve capable of shutting off the raw fuel from the anode electrode outlet toward the off-gas passage of the fuel cell, A third shutoff valve capable of shutting off the raw fuel from the anode gas passage to the offgas passage, bypassing the fuel cell,
The diagnostic means includes (i) at least a modification of the reformer and the fluid passage in a state in which the first cutoff valve and the third cutoff valve are closed so that the raw fuel is not supplied to the fuel cell. Performing a first diagnosis of leakage in a region downstream of the mass part, and (ii) closing the second shut-off valve and the third shut-off valve and opening the first shut-off valve, A fuel cell system which supplies the anode electrode of the fuel cell and diagnoses leakage of the fuel cell. 9. The combustion part according to claim 1, wherein a combustion part that heats the reforming part by combustion is provided, and the combustion part includes a region downstream of the reforming part of the reformer and the fuel. It is possible to communicate with the outlet of the anode of the battery,
The diagnostic means burns in the combustion section by supplying the raw fuel discharged from a region downstream of the reformer or an outlet of the anode of the fuel cell to the combustion section at the time of diagnosis. A fuel cell system. 10. When the reforming device of the fuel cell system is started for the first time after the leakage diagnosis, the diagnosis means is configured to change the reforming device more than when the reforming device is normally started. A fuel cell system characterized by setting a high S / C value for the quality device.
Here, the value of S / C is (number of moles of H ₂ O contained in the reforming water supplied to the reformer) / (carbon component contained in the raw fuel supplied to the reformer) Number of moles). In one of Claims 1-10, when the predetermined time has passed since the end of the previous operation of the reformer, or when the temperature of the reforming unit is lower than a predetermined temperature, the diagnostic means includes: Performing the leak diagnosis; and
When the predetermined time has not elapsed since the end of the previous operation of the reformer, or when the temperature of the reforming unit is equal to or higher than a predetermined temperature, the diagnosis unit does not execute the leakage diagnosis. Battery system.   12. The diagnostic device according to claim 1, wherein if the leakage is not detected, the diagnostic unit seals the raw fuel as a purge fluid or a sealing fluid in the reformer and / or the fuel cell. A fuel cell system characterized by performing an enclosing operation.

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