JP5772481B2 - Fuel cell output voltage recovery apparatus and method - Google Patents

Description

  The present invention relates to an apparatus and method for recovering an output voltage of a fuel cell, and more particularly to an apparatus and method for recovering an output voltage of a fuel cell having means and process for recovering an output voltage lowered by an odorant.

  In a fuel cell system in which gas leakage is detected by adding an odorant to the fuel gas supplied to the fuel cell, if the operation is continued, there is a voltage drop even when no odorant is added. In addition, the fuel cell output characteristics may gradually deteriorate due to the odorant. Patent Documents 1 and 2 describe that an odorant is removed from a fuel gas and supplied to a fuel cell. Specifically, Patent Document 1 describes that the odorant is adsorbed and removed with activated carbon or zeolite, and Patent Document 2 condenses or sublimates the odorant by cooling the fuel gas. It is described that it is separated and removed.

  In Patent Document 3, an odorant-containing gas is supplied to a fuel cell to generate power, and when the odorant has accumulated in the fuel cell, the temperature of the fuel cell is raised to remove the odorant from the fuel cell. It is described to do.

JP 2005-327650 A JP2008-257933 JP2008-41554

  In Patent Documents 1 and 2, it is necessary to remove the odorant from the entire amount of the fuel gas supplied to the fuel cell, the odorant removal device such as the adsorption device is enlarged, the fuel cell power generation system is enlarged, and the equipment The cost will be high. Furthermore, the running cost of power generation increases. In Patent Document 3, a temperature raising means for raising the temperature of the fuel cell when the odorant has accumulated in the fuel cell is required, and a safety device for raising the temperature of the fuel cell is required. Thus, the fuel cell power generation system becomes larger and the cost becomes higher. Furthermore, since the temperature of the fuel cell is raised to a high temperature, a steady power generation operation cannot be performed during this time, and the power generation efficiency decreases.

  The present invention solves the above-mentioned various problems, removes the influence of odorants on the fuel cell by simple means, and can stably operate the fuel cell at low cost and continuously. An object of the present invention is to provide an output voltage recovery apparatus and method for a fuel cell.

An output voltage recovery device for a fuel cell according to the present invention is an output voltage recovery device for a fuel cell that generates power by supplying an odorant-containing fuel gas to the fuel cell, and intermittently supplies the odorant to the fuel cell. The odorant-free fuel gas is supplied instead of the odorant-containing fuel gas to remove the odorant adhering to the fuel cell, and the output voltage of the fuel cell is reduced by the supply of the odorant-containing fuel gas. The odorant-free fuel gas supply means recovers the odorant-free fuel gas supply means, the odorant-free fuel gas supply means removes the odorant-containing fuel gas and removes the odorant-containing fuel gas. It has a means for producing gas.

The fuel cell output voltage recovery method of the present invention is a fuel cell output voltage recovery method comprising a step of supplying a fuel cell with an odorant-containing fuel gas to generate power, and the fuel cell is intermittently attached to the fuel cell. By supplying the odorant-free fuel gas instead of the odorant-containing fuel gas , the odorant adhering to the fuel cell is removed, and the fuel cell is reduced by the supply of the odorant-containing fuel gas. An output voltage recovery method for a fuel cell that executes a step of recovering an output voltage, characterized in that the odorant-free fuel gas is a gas obtained by removing an odorant-containing fuel gas from an odorant. To do.

  In the present invention, it is preferable to supply the odorant-free fuel gas when the output voltage of the fuel cell becomes a predetermined value or less.

  In the present invention, the fuel gas is preferably hydrogen gas, and the odorant is preferably cyclohexene.

  In the present invention, the supply time of the odorant-free fuel gas is preferably 1 second or longer, particularly 10 seconds or longer.

  In the present invention, the fuel cell is preferably a polymer electrolyte fuel cell or an alkaline electrolyte fuel cell.

  In the fuel cell output voltage recovery apparatus and method of the present invention, the fuel cell is supplied with the odorant-containing fuel gas to generate power, and the power generation output of the fuel cell decreases intermittently, for example, due to the influence of the odorant. In this case, a fuel gas containing no odorant is supplied to the fuel cell. By supplying the odorant-free fuel gas to the fuel cell in this way, the odorant adhering to the fuel cell is removed, and the power generation output of the fuel cell is recovered. In the present invention, the fuel cell continues to generate power while supplying the fuel cell with the odorant-free fuel gas. In the present invention, a configuration for removing the odorant by raising the temperature of the fuel cell is unnecessary, and the configuration of the fuel cell system is simple. In addition, since the temperature of the fuel cell is not increased unnecessarily, a simple safety measure system is sufficient.

  In the present invention, when the output voltage of the fuel cell becomes equal to or lower than a predetermined value, the odorant-free fuel gas is supplied to the fuel cell instead of the odorant-containing fuel gas. It can be kept above a predetermined value.

  By using a gas obtained by removing the odorant-containing fuel gas from the odorant-containing fuel gas as the odorant-free fuel gas, the odorant-free fuel gas can be easily produced.

  The present invention is suitable for application when the fuel gas is hydrogen gas and the odorant is cyclohexene. In the present invention, the fuel cell output can be recovered by supplying the odorant-free fuel gas for a short time, for example, 1 second or longer. The present invention is suitable for application when the fuel cell is a polymer electrolyte fuel cell.

It is a block diagram of a fuel cell power generation system. It is a block diagram of another fuel cell power generation system. It is a schematic diagram of the test apparatus of an Example. It is a graph which shows an experimental result.

  Hereinafter, the present invention will be described in detail.

  As the fuel cell used in the apparatus and method of the present invention, various fuel cells such as a polymer electrolyte fuel cell, a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, and an alkaline electrolyte fuel cell are used. Of these, polymer electrolyte fuel cells or alkaline electrolyte fuel cells are preferred. This polymer electrolyte fuel cell usually has a cell stack in which a plurality of cells are stacked. Each cell includes a solid polymer electrolyte membrane, a fuel electrode (anode) and an air electrode (oxidizer electrode: cathode) that sandwich the solid polymer electrolyte membrane from both sides, and a fuel electrode side separator and air that sandwich the fuel electrode and air electrode. It consists of a pole-side separator.

  The fuel electrode has a diffusion layer and a catalyst layer. A fuel gas containing hydrogen such as hydrogen gas or hydrogen rich gas is supplied to the fuel electrode by the fuel supply system. The fuel gas supplied to the fuel electrode is diffused in the diffusion layer and reaches the catalyst layer. In the catalyst layer, hydrogen is separated into protons (hydrogen ions) and electrons. Hydrogen ions move to the air electrode through the solid polymer electrolyte membrane, and electrons move to the air electrode through an external circuit. As the catalyst, platinum is usually used, but is not limited thereto, and may be a platinum alloy or a non-platinum catalyst.

  The air electrode has a diffusion layer and a catalyst layer, and an oxidant gas such as air is supplied to the air electrode by an oxidant supply system. The oxidant gas supplied to the air electrode is diffused in the diffusion layer and reaches the catalyst layer. In the catalyst layer, water is generated by a reaction between the oxidant gas, hydrogen ions that have reached the air electrode through the solid polymer electrolyte membrane, and electrons that have reached the air electrode through the external circuit. The electrons passing through the external circuit during the reaction at the fuel electrode and the air electrode are used as electric power for a load connected between both terminals of the fuel cell stack.

  Hydrogen gas is preferred as the fuel gas. In general, cyclohexene, mercaptans, sulfides, thiophenes and the like are used as odorants for fuel gas. When the fuel gas is hydrogen gas, the following compounds are preferred, and cyclohexene is particularly preferred. . 1-pentene, cis-2-pentene, trans-2-pentene, 2-methyl 1-butene, 3-methyl 1-butene, 2-methyl 2-butene, allene, methyl allene, ethyl allene, 1,3-pentadiene 2-methyl 1,3-butadiene, 2,3-dimethyl 1,3-butadiene, 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,3,5-hexatriene, 1- Butyne, 2-butyne, styrene, vinylacetylene, heptene, octene, nonene, decene, propylene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1,5-hexadiene-3-in, diisobutylene 1-hexene, isoprene, 1,3-butadiene, 1,2-butadiene, cyclopentene, cyclopentadiene (disi Lopentanediene), 1,3-cyclohexadiene, 1,3-cycloheptadiene, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, 4-vinylcyclohexene-1, 1-vinylcyclohexene- 1,5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, bicyclopentadiene, cyclohexene, 1-methylpyrrole, pyrazine, 2-methylpyrazine, 2-methyl-3-isobutylpyrazine, 2,3-dimethylpyrazine 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2,3,5-trimethylpyrazine, 2-ethylpyrazine, 2-propylpyrazine, 2-vinylpyrazine, 2-allylpyrazine, 2-picoline, α. p-dimethyl-styrene, cumene, 2,5-diethylpyrazine, limonene, mesitylene, 2-methylnaphthalene, 3-methylindole (skatole), myrcene, α-pinene, 1-octen-3-one, 2,3- Butanedione, pentane-2,3-dione, hexane-2,5-dione, heptane-2,5-dione, ethylidene diethyl ether, isopropanol, n-butanol, isobutanol, amyl alcohol, propargyl alcohol, β, γ- Hexenol (cis-hexen-1-ol), formaldehyde, acetaldehyde, propionaldehyde, hexanal (caproaldehyde), cuminaldehyde, acetone, 2-octanone, 3-octanone, diacetyl (2,3-butanedione), acetophenone, methylphospho Mate, methyl acetate, methyl propionate, methyl phenyl acetate, ethyl formate, ethyl acetate, isopropyl formate, isoamyl acetate, n-amyl acetate, phenyl ethyl formate, 2-isopentenyl acetate, ethyl propionate, butyl Acetate, isobutyl acetate, amyl propionate, ethyl caproate, amyl butyrate, ethyl caprylate, ethyl caprate, hexyl butyrate, ethyl cinnamate, benzyl acetate, ethyl crotonate, ethyl 3,3-dimethyl acrylate, Ethyl-4-methyl-4-pentenoate, ethyl-4-methyl-3-pentenoate, ethyl hept-3-enoate, ethyl pyruvate, propyl crotonate, methyl Acrylate, butyl acrylate, allyl acrylate, methyl methacrylate, menthyl acetate, bornyl acetate, β-phenyl ethyl acetate, allyl caproate, ethyl methyl phenyl glycidate, p-cresyl acetate, acetol acetate, ethyl 9-decenoate 2,3-octanedione, methyl-3-acetoxy-butanoate, propionoin, 2-methyl-2-pentenal, acetoin acetate, methyl 3-hydroxy-butyrate, 2-methyl-1-hepten-3-ol, 8-nonene 2-one, acetoin, 3-methyl-3-butenyl acetate, tetrahydrocitral, allyl alcohol, butanal (butyraldehyde), 2,3-butanedione (diacetyl), isobutyl cello Rub, isobutyraldehyde, carbitol acetate, 2-decenal, decanal, diisobutyl carbinol, dodecanal (lauryl aldehyde), ethyl acrylate, ethyl butyrate, ethyl valerate, ethyl vinyl ketone, ethyl 2-methylbutyrate, heptanal, 1 -Heptanol, 2-heptanone, 2-heptenal, 2-hexenol, mesityl oxide, 2-methylbutanal-1, 3-methylbutanal-1, 2-methylbutanol, methyl isoamyl ketone (5-methyl-2- Hexanone), 2-methyl-1-pentanol, 2-methylbutyl acetate, 2-methylpropanal (isobutyraldehyde), 2-nonanal, n-nonanal (pelargonaldehyde), 2-octenal, octa (N-caprylaldehyde), octyl acetate, 1-penten-3-one (ethyl vinyl ketone), isopentanal, pentanal (valeraldehyde), 2,4-pentanedione (acetylacetone), isopentyl acetate (isoamyl) Acetate), pentyl acetate (n-amyl acetate), propanal (propionaldehyde), propanoic acid, propylbutyrate, undecanal, butyroin, tetrahydrofuran, 2-methyltetrahydrofuran, cyclohexene oxide, m-cresol, N- (2 ' -Furfuryl) pyrrole, 2-pyrrolealdehyde, 5-methyl-2-pyrrolealdehyde, N-ethylpyrrolealdehyde, 2-acetyl-N-methylpyrrole, diketene, 5-acetyl-2-methyl Tyloxazole, 2-acetylfuran, 2-methylfuran, furfural, furfuryl acetone, 5-methyl-2-furfural, dihydrofuranone, cyclopentanone, phenyl n-butyrate, 2-phenyl-2-butenal, difurfuryl ether Chrysanthenone, 2-butene-4-olide, 2-methoxyphenol (Gaiacol), 2-methoxy-3-ethylpyrazine, 2-methoxy-3-isobutylpyrazine, 2-methoxy-3-isobutylpyridine, 2-methoxy -3-isopropylpyrazine, 2-methoxy-3-propylpyrazine, anisole, benzaldehyde, 1,8-cineol, cyclopentyl acetate, 2-ethoxy-3-ethylpyrazine, 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) , Phenyl ether.

  When the odorant-containing fuel gas is a cyclohexene-containing hydrogen gas, it is preferable that cyclohexene is added in an amount of about 0.1 to 5000 ppm, particularly about 1 to 300 ppm relative to the hydrogen gas. In addition, a nitrogen compound, hydrocarbons, etc. may be added with cyclohexene. Depending on the mode of the odorant-containing fuel gas, the odorant-containing fuel gas may be supplied after removing the odorant as a pretreatment up to this level of concentration.

  The odorant-free fuel gas may be a fuel gas with no odorant added, but is preferably a odorant-removed treatment of the odorant-containing fuel gas. As this odorant removal treatment means, an adsorption device using an adsorbent such as activated carbon or zeolite is suitable. This adsorbing device is not always operated, but is operated only when the fuel gas containing no odorant is supplied to the fuel cell, so that a small capacity is sufficient. In addition, you may introduce | transduce odorant-free fuel gas directly from the outside as needed, without using an adsorbent.

  FIG. 1 is a configuration diagram of a fuel cell power generation system using an odorant remover and a fuel cell. The odorant-containing fuel gas is supplied to the fuel cell 3 through the gas supply line 1 and the valve 2. A valve 5 and an odorant remover 6 are provided in a bypass line 4 that bypasses the valve 2. The output voltage of the fuel cell 3 is detected by the voltmeter 10, and this detected voltage is input to the controller 11. The controller 11 compares the predetermined voltage set in advance with the detected voltage, and controls the valves 2 and 5 to control the odorant in the fuel cell 3 when the detected voltage falls below the predetermined value. A valve drive control circuit for supplying non-containing fuel gas.

  During normal operation, the valve 2 is opened and the valve 5 is closed, and the entire amount of fuel gas is supplied to the fuel cell 3 as it is to generate power.

  When the output voltage of the fuel cell 3 becomes a predetermined value or less, the valve 2 is closed, the valve 5 is opened, the fuel gas is completely passed through the odorant remover 6 to remove the odorant, Supply to battery 3. In this embodiment, an adsorption device filled with an adsorbent such as activated carbon or zeolite is used as the odorant remover 6. When the odorant is cyclohexene, the cyclohexene concentration in the fuel gas that has passed through the odorant remover 6 is preferably 10 ppm or less, particularly preferably 1 ppm or less.

  Thus, when the odorant-free fuel gas substantially containing no odorant is supplied to the fuel cell, the odorant or its decomposition product adhering to the catalyst of the fuel cell, in particular, in the fuel cell. It is removed by a physical removal action such as desorption or a chemical removal action, and the power generation voltage (output voltage) of the fuel cell is restored.

  When the fuel gas is hydrogen gas containing about 0.1 to 5000 ppm of cyclohexene and the fuel cell is a polymer electrolyte fuel cell, the odorant-containing fuel gas is supplied to the fuel cell for 1 second to 1000 hours, particularly 10 After feeding for seconds to 1000 hours, especially 1 hour to 1000 hours, cyclohexene-free hydrogen such as cyclohexene-removed hydrogen gas is added for 1 second to 100 hours, especially 10 seconds to 100 hours, especially 1 hour to 100 hours, and even 10 hours. The fuel cell output voltage can be sufficiently recovered by supplying about 100 hours.

  In the system of FIG. 1, while supplying the odorant-containing fuel gas to the fuel cell 3, the adsorbent of the odorant remover 6 can be regenerated or replaced as necessary.

  In the above description, the odorant-free fuel gas is supplied to the fuel cell 3 when the output voltage of the fuel cell 3 falls below a predetermined value, but even when the output voltage of the fuel cell 3 does not drop that much. An odorant-free fuel gas may be supplied to the fuel cell 3 intermittently (for example, periodically) to suppress a decrease in the output voltage of the fuel cell 3.

  In the present invention, the supply speed when supplying the odorant-free gas to the fuel cell 3 is made higher than when supplying the odorant-containing gas, and the output voltage of the fuel cell 3 is recovered in a short time. Good. The fuel cell may be held in an open circuit while supplying the odorant-free fuel gas to the fuel cell 3. Further, the supply amount of the odorant-free fuel gas may be increased while temporarily maintaining the generated voltage.

  In the present invention, a tank for temporarily storing the fuel gas subjected to the odorant removal treatment may be provided. The tank may be filled with a hydrogen storage alloy. The fuel gas in the tank may be supplied to the fuel cell at a higher supply rate than the supply rate during steady operation.

  The system shown in FIG. 1 is an example of the present invention, and the present invention may take other forms. The system of FIG. 2 is configured such that when a plurality of fuel cells 3 are provided, the fuel gas from which the odorant has been removed by one odorant remover 5 can be supplied to each fuel cell 3. is there. In FIG. 2, the detection voltage of the voltmeter 10 of each fuel cell is input to one controller 12, and the supply control of the odorant-free fuel gas to each fuel cell 3 is performed by the controller 12. . Although not shown, when a plurality of odorant removers 5 are installed in parallel and the odorant is supplied by some odorant removers, it is adsorbed by some other odorant removers. The material may be removed or replaced.

[Example 1]
The fuel cell was operated by supplying cyclohexene-added hydrogen gas as the odorant-containing fuel gas to the fuel cell and intermittently supplying cyclohexene-free hydrogen gas as the odorant-free fuel. Specifically, a JARI (Japan Automobile Research Institute) standard cell having a membrane / electrode assembly (MEA) with an electrode area of 25 cm ² (5 cm square) was operated as a single cell. The catalyst of MEA is TEC10E50E, and the amount of catalyst is 0.2 mg Pt / cm ² for both electrodes. The electrolyte membrane is Nafion (registered trademark) NRE211.

The current density was kept constant at 0.25 A / cm ² and was controlled so as to always have the same current density during the addition of cyclohexene. The fuel utilization rate (Uf) was 90%, and the air utilization rate (Uo) was 55%. The cell temperature was 65 ° C., and the humidification dew point of the gas flowing through the anode and cathode was both 65 ° C.

  A standard gas having a cyclohexene of 5000 ppm was prepared and added to hydrogen or air after humidification so as to have a cyclohexene concentration of 100 ppm. FIG. 3 shows an outline of the test apparatus.

  For the power generation characteristic evaluation of the fuel cell, AUTOPEM manufactured by Toyo Corporation was used.

  Until 535 hours passed from the start of operation of the fuel cell, hydrogen gas without addition of cyclohexene was supplied to the fuel cell. Thereafter, hydrogen gas containing 100 ppm of cyclohexene was supplied for 406 hours. Subsequently, after adding cyclohexene-free hydrogen gas for 2 hours, 100 ppm of cyclohexene-added hydrogen gas was supplied for 837 hours. Further, after that, cyclohexene-free hydrogen gas was supplied for 600 hours.

  The change with time of the output voltage of the fuel cell is shown in FIG. As shown in FIG. 4, when the addition of cyclohexene was started after 535 hours, the cell voltage gradually decreased. After adding 406 hours of cyclohexene, the cell voltage was recovered by supplying hydrogen gas without cyclohexene added for 2 hours. Thereafter, after the cyclohexene addition operation for 837 hours, when the addition of cyclohexene was stopped, the cell voltage was recovered again. In addition, when cyclohexene addition is restarted and then the supply of hydrogen gas without addition of cyclohexene is continued, the cell voltage becomes an extrapolated line (dotted line) level of the cell voltage transition at the initial stage when cyclohexene is not mixed. It was.

  From the above, it was confirmed that when cyclohexene was mixed from the anode side, the cell voltage decreased, but it was reversibly recovered by stopping the addition of cyclohexene.

3 Fuel Cell 6 Odorant Remover 10 Voltmeter 11, 12 Controller

Claims (11)

A fuel cell output voltage recovery device for generating power by supplying an odorant-containing fuel gas to a fuel cell,
An odorant-free fuel gas is intermittently supplied to the fuel cell instead of the odorant-containing fuel gas to remove the odorant adhering to the fuel cell, and the odorant-containing fuel gas An odorant-free fuel gas supply means for recovering the output voltage of the fuel cell that has been reduced by the supply of
The odorant-free fuel gas supply means is a fuel cell output voltage recovery device having means for producing an odorant-free fuel gas by removing the odorant-containing fuel gas from the odorant. 2. The fuel cell output voltage detection means according to claim 1, further comprising a control means for operating the odorant-free fuel gas supply means when the detection voltage of the detection means falls below a predetermined value. An output voltage recovery device for a fuel cell.   3. The output voltage recovery device for a fuel cell according to claim 1, wherein the fuel gas is hydrogen gas and the odorant is cyclohexene.   4. The output voltage recovery device for a fuel cell according to claim 1, wherein the supply time of the odorant-free fuel gas is 1 second or longer.   5. The output voltage recovery device for a fuel cell according to claim 1, wherein the fuel cell is a polymer electrolyte fuel cell or an alkaline electrolyte fuel cell. In the method of recovering the output voltage of the fuel cell, the method includes the step of supplying the odorant-containing fuel gas to the fuel cell to generate power,
By intermittently supplying the fuel cell with an odorant-free fuel gas instead of the odorant-containing fuel gas , the odorant adhering to the fuel cell is removed, and the odorant-containing fuel is removed. A method for recovering the output voltage of a fuel cell, comprising performing a step of recovering the output voltage of the fuel cell that has been lowered by the supply of gas ,
The fuel cell output voltage recovery method, wherein the odorant-free fuel gas is a gas obtained by removing the odorant-containing fuel gas from the odorant.   7. The fuel cell output voltage recovery method according to claim 6, wherein the odorant-free fuel gas is supplied when the output voltage of the fuel cell becomes a predetermined value or less.   8. The output voltage recovery method for a fuel cell according to claim 6, wherein the fuel gas is hydrogen gas.   8. The method of recovering an output voltage of a fuel cell according to claim 6, wherein the fuel gas is hydrogen gas and the odorant is cyclohexene.   10. The fuel cell output voltage recovery method according to claim 6, wherein the supply time of the odorant-free fuel gas is 1 second or longer.   11. The output voltage recovery method for a fuel cell according to any one of claims 6 to 10, wherein the fuel cell is a polymer electrolyte fuel cell or an alkaline electrolyte fuel cell.

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