JP4168511B2 - Apparatus for reducing carbon monoxide concentration in hydrogen gas containing carbon monoxide and fuel cell power generation system using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell or an electrochemical hydrogen purification apparatus used in, for example, an electric vehicle or the like that performs an electric power generation or a purification of hydrogen gas using an electrochemical reaction. More specifically, for example, in a fuel cell, the present invention relates to an apparatus for reducing the concentration of carbon monoxide contained when methanol or natural gas is converted into reformed fuel gas containing hydrogen as a main component by steam reforming or partial oxidation reforming. .
[0002]
[Prior art]
As is well known, a fuel cell is a typical example of an electrochemical device. A pair of electrodes are brought into contact with each other through an electrolyte, fuel is supplied to one electrode, and an oxidant is supplied to the other electrode. It is a device that converts chemical energy directly into electrical energy through electrochemical reaction. There are several types of fuel cells depending on the electrolyte. Recently, a solid polymer fuel cell using a solid polymer electrolyte membrane as an electrolyte has attracted attention as a fuel cell capable of obtaining high output. When hydrogen gas is supplied to the fuel electrode, oxygen gas is supplied to the oxidant electrode, and current is taken out from the external circuit, the following reaction occurs.
Fuel electrode reaction: H ₂ → 2H ⁺ + 2e ^- (1)
Oxidant electrode reaction: 2H ⁺ + 2e ^- + 1 / 2O ₂ → H ₂ O (2)
[0003]
At this time, if a catalyst such as platinum on the electrode acts effectively, the reaction of Formula 1 hardly causes an overvoltage and proceeds smoothly.
On the other hand, when a hydrocarbon such as methanol that is easy to handle is used as the fuel, it is supplied after being reformed into hydrogen by a reaction as shown in Formula 3 by a reformer.
Reforming reaction: CH _Three OH + H ₂ O → 3H ₂ + CO ₂ (3)
However, a trace amount of carbon monoxide (CO) is mixed in the fuel by the next shift reaction.
Shift reaction: CO ₂ + H ₂ → CO + H ₂ O (4)
Especially in electrochemical devices such as polymer electrolyte fuel cells with low operating temperatures, the problem is that the catalyst is poisoned by the incorporation of tens of ppm of CO, resulting in an increase in overvoltage of the anode reaction and a decrease in characteristics. It has become.
[0004]
Therefore, many attempts have been made in the past to reduce the CO concentration in the reformed fuel gas.
FIG. 5 is a diagram schematically showing a configuration of a general CO concentration reduction device (CO selective oxidizer) in the fuel cell according to Conventional Example 1. In the figure, 29 is a first CO selective oxidizer, 30 is a second CO selective oxidizer, 31 is a reformed fuel gas inlet, 32 is a connecting pipe, 33 is a CO-treated reformed fuel gas outlet, and 34 is a first. One CO selective oxidizer air inlet 35 is a first CO selective oxidizer air inlet 35.
[0005]
Each of the CO selective oxidizers 29 and 30 is filled with a platinum fine particle catalyst. Since CO is strongly adsorbed on the surface of the platinum fine particle catalyst, it is oxidized in preference to hydrogen by the added air, and carbon dioxide (CO ₂ ). However, excess air oxidizes hydrogen and converts it to water. Therefore, a method of dividing the first CO selective oxidizer 29 and the second CO selective oxidizer 30 and adding a small amount of air in two portions is used. However, when the CO concentration changes, there is a problem that it is difficult to control the amount of air added and the amount of hydrogen consumed is large. This means that the reformed fuel gas is consumed unnecessarily, and the efficiency of the polymer electrolyte fuel cell power generation system is reduced. In addition, the air contains nitrogen four times as much as oxygen and remains in the reformed fuel gas after the CO concentration is reduced, so that the hydrogen concentration is diluted and the performance of the polymer electrolyte fuel cell is reduced. There was a problem.
[0006]
As a revolutionary method for improving the negative effects of adding air to the gas to be treated and consuming hydrogen or diluting hydrogen with nitrogen, a method of applying a pulsed voltage was invented. It was. Japanese Patent Application Laid-Open No. 10-216461 by the same applicant as the present invention states that “a method of removing carbon monoxide from hydrogen gas containing carbon monoxide, an electrochemical device thereof, an operation method thereof, a fuel cell operation method, and a fuel A method of generating hydrogen at a counter electrode by reacting carbon monoxide and water in an electrochemical cell is disclosed under the title of “battery power generation system”. FIG. 6 is a diagram schematically showing a configuration of a CO concentration reducing apparatus according to Conventional Example 2 described in the above publication. In the figure, 41 is a CO reduction cell, 44 is a pulse voltage application power source, 7 is a gas inlet to be processed, 10 is a connecting portion, 11 is a CO-treated gas outlet, and 12 is a solid polymer electrolyte membrane. The CO reduction cell 41 includes a pair of gas diffusion electrodes disposed on both surfaces of an ion conductive electrolyte membrane via a catalyst layer such as platinum, and gas flow paths are formed on both sides thereof.
[0007]
In such a configuration, the reformed fuel gas is supplied as hydrogen gas containing CO from the gas inlet 7 to be processed, and the gas inlet 7 side between the two electrodes of the CO reduction cell 41 is supplied by the pulse voltage application power source 44. When a pulsed voltage is continuously applied so that the electrode of the anode becomes positive, CO reacts with moisture at the anode, and CO ₂ Are converted into protons and electrons, and hydrogen is generated from the protons and electrons at the cathode. In this way, CO in the gas to be treated is oxidized and removed and the CO concentration is reduced.
[0008]
Although this method consumes electric energy for electrolysis, since it is not necessary to add air, the gas to be treated is not diluted with nitrogen. Further, hydrogen is not wasted and converted to water. However, if a pulse voltage is applied in a state where CO is not sufficiently adsorbed on the platinum catalyst, hydrogen is oxidized to become protons and electrons, and becomes hydrogen at the counter electrode. In this phenomenon, since one hydrogen is consumed and one hydrogen is generated, there is no fear of consuming hydrogen unnecessarily. However, it is necessary to pass an extra current, so that power consumption increases. There was a problem.
[0009]
In order to prevent excessive power consumption, Japanese Patent Laid-Open No. 10-216461 discloses that a plurality of CO reduction cells are connected in series, and the pulse width of the downstream CO reduction cell is set to the upstream side. A method of making it smaller than that of the CO reduction cell is also described. However, for example, when the reforming amount changes in a fuel cell power generation system, the CO concentration contained in the reformed fuel gas changes greatly depending on the temperature of the reformer, etc., so this method cannot be used. There is a problem that CO cannot be sufficiently reduced or excessive power is consumed.
[0010]
[Problems to be solved by the invention]
The conventional CO concentration reducing apparatus is configured as described above. In the conventional example 1, when the CO concentration changes, there is a problem that it is difficult to control the amount of air added and the amount of hydrogen consumed is large. . Further, the conventional example 2 also has a problem in that when the CO concentration greatly changes, the CO cannot be sufficiently reduced or excessive power may be consumed.
[0011]
The present invention has been made to solve the above-described problems of the prior art, and even when CO is selectively oxidized by electrolysis and the CO concentration changes greatly, hydrogen and power are wasted. To provide a device for reducing the carbon monoxide concentration in hydrogen gas containing carbon monoxide that can efficiently and reliably reduce the CO concentration without consuming excessively, and a fuel cell power generation system using the device It is aimed.
[0012]
[Means for Solving the Problems]
The apparatus for reducing the concentration of carbon monoxide in hydrogen gas containing carbon monoxide according to the first invention is such that a pair of gas diffusion electrodes are disposed on both surfaces of an ion conductive electrolyte membrane via catalyst layers, respectively. The first and second CO-reduced power cells, the first and second CO-reduced cells, respectively, and a voltage-applied first power source and a voltage-applied second power source, each of which includes carbon monoxide. After supplying hydrogen gas to the anode of the CO-reduced first cell, means for flowing the anode of the CO-reduced second cell, the cathode of the CO-reduced second cell, the cathode of the CO-reduced first cell, and the CO-reducing second cell CO concentration monitoring means for monitoring the CO concentration at the anode outlet is provided, and a pulsed voltage is continuously applied to the CO-reduced first cell using the voltage application first power source. A pulsed voltage is intermittently applied using a voltage application second power source based on the signal of the O concentration monitoring means, and carbon monoxide is reacted with moisture at the anodes of the CO reduced first cell and the CO reduced second cell. The carbon is converted into carbon dioxide, protons and electrons, and hydrogen is generated from the protons and electrons at the cathodes of the CO-reducing first cell and the CO-reducing second cell.
[0013]
The apparatus for reducing the carbon monoxide concentration in the hydrogen gas containing carbon monoxide according to the second invention is the apparatus according to the first invention, wherein the interval at which the pulse voltage is applied to the CO-reduced second cell is within a predetermined range. The period of the pulsed voltage of the CO-reduced first cell is controlled so as to be settled.
[0014]
A fuel cell power generation system according to a third aspect of the present invention supplies a reformed fuel gas reformed by a reformer to a fuel electrode of a fuel cell, and supplies an oxidant gas to an oxidant electrode of the fuel cell to generate power. In the fuel cell power generation system to be performed, the concentration of carbon monoxide in the hydrogen gas containing carbon monoxide according to the first or second invention is reduced in the reformed fuel gas path between the reformer and the fuel electrode. An apparatus is arranged so that the concentration of carbon monoxide contained in the reformed fuel gas is reduced and supplied to the fuel electrode.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on the drawings with the same reference numerals assigned to the same or corresponding parts as in the prior art.
Embodiment 1 FIG.
FIG. 1 is a diagram schematically showing a configuration of an apparatus for reducing the carbon monoxide concentration in hydrogen gas containing carbon monoxide, that is, a CO concentration reducing apparatus, according to Embodiment 1 of the present invention. In the figure, reference numeral 1 is a CO-reduced first cell, 2 is a CO-reduced second cell, and 3 is a CO monitor cell. These cells all have a pair of gas diffusion electrodes as an ion-conductive electrolyte membrane, that is, a solid polymer electrolyte membrane. 12 are arranged on both sides via a catalyst layer. 4 is a first power source for applying pulse voltage, 5 is a second power source for applying pulse voltage, 6 is an ammeter, 7 is a gas inlet, 8 is a gas pipe, 9 is a DC power source, 10 is a CO-treated gas pipe, 11 is A CO-treated gas outlet 12 is a solid polymer electrolyte membrane. As an example, the electrode effective area of the CO reduced first cell 1 and the CO reduced second cell 2 is 225 cm. ² The effective area of the CO monitor cell 3 is 1 cm ² It is. Note that the CO monitor cell 3 is heated to 80 ° C. in order to know the absolute value of the CO concentration while keeping the temperature constant.
Note that a sampling port may be provided in the CO-treated gas pipe 10 instead of the CO monitor cell 3 so that the CO concentration can be monitored with an infrared CO gas sensor.
[0016]
The CO-reduced first cell 1 is applied with a pulsed voltage by the pulse voltage application first power source 4 and is contained in the gas to be processed, and the carbon monoxide adsorbed on the anode (anode) catalyst is Oxidized to carbon dioxide. That is, the reaction of Formula 5 generates carbon dioxide, protons, and electrons from carbon monoxide and water. On the other hand, hydrogen is generated from protons and electrons at the cathode (cathode).
CO + H ₂ O → CO ₂ + 2H ⁺ + 2e ^- (5)
2H ⁺ + 2e ^- → H ₂ (6)
[0017]
By these reactions, most of the carbon monoxide contained in the gas to be treated in the first CO-reducing cell 1 is converted to carbon dioxide. The untreated carbon monoxide gradually adsorbs and accumulates on the catalyst of the anode of the second CO-reduced second cell 2. On the other hand, in the CO monitor cell 3, an applied voltage of 0.5 V is always applied by the DC power supply 9. Since the effective area is small, a slight current of 0.5 amperes flows, and if it is subjected to CO poisoning, the flowing current decreases, so that it can be easily detected by the ammeter 6. When carbon monoxide cannot be completely adsorbed by the catalyst of the anode of the second CO 2 reduction cell 2 and slips toward the CO monitor cell 3, it is detected by the ammeter 6 and the pulse voltage application second power source 5 is activated. Thus, a pulse voltage is applied to the CO-reduced second cell 2, and carbon monoxide that could not be removed in the CO-reduced second cell 2 by the CO-reduced first cell 1 is converted into carbon dioxide by the reaction of the above-described equations 5 and 6. Converted.
[0018]
The CO concentration at the CO-treated gas outlet 11 is effectively reduced by the continuous CO oxidation treatment of the CO reduced first cell 1 and the intermittent CO oxidation treatment of the CO reduced second cell 2. If a voltage is applied when carbon monoxide is not sufficiently adsorbed on the catalyst, the reactions of equations 7 and 8 occur at the anode and the cathode, respectively, and power is wasted. In the embodiment, since the voltage is applied after confirming the adsorption of carbon monoxide in the CO-reducing second cell 2 in the CO monitor cell 3, the ratio of hydrogen that is wasted is reduced.
H ₂ → 2H ⁺ + 2e ^- (7)
2H ⁺ + 2e ^- → H ₂ (8)
[0019]
FIG. 2 is a cross-sectional view showing the configuration of the first cell with reduced CO concentration according to the present embodiment. In the figure, 13 is an anode channel plate, 14 is a cathode channel plate, 15 is an anode, 16 is a cathode, 17 is an anode gas channel, and 18 is a cathode gas channel. The anode 15 and the cathode 16 are obtained by mixing carbon carrying platinum fine particles as a catalyst layer with a solvent and a liquefied solid polymer electrolyte, followed by pasting on one side of carbon paper having an outer shape of 15 cm × 15 cm and a thickness of 0.2 mm. Each was produced by applying to a thickness of 20 μm and drying. Next, the anode 15 and the cathode 16 were superposed on both surfaces of the solid polymer electrolyte membrane 12 via catalyst layers, respectively, and hot pressed to produce an electrode / membrane assembly. The anode channel plate 13 with the anode gas channel 17 formed on the both sides of the electrode / membrane assembly thus prepared and the cathode gas channel plate 14 with the cathode gas channel 18 formed thereon are disposed in the CO. A concentration-reduced first cell 1 is formed. A Nafion solution manufactured by Aldrich was used as the liquefied solid polymer electrolyte, and Nafion 112 manufactured by DuPont was used as the solid polymer electrolyte membrane 12.
[0020]
The anode channel plate 13 and the cathode channel plate 14 are carbon plates, and serpentine type channels are used as the anode gas channel 17 and the cathode gas channel 18. These are PEFC (solid polymer fuel cell) 225cm ² Although the structure is similar to that of a class single cell housing, the depth of the flow path is set to three times the normal (1.5 mm) in order to allow a large flow rate to flow. The CO concentration-reduced first cell 1 was sandwiched between two gold-plated copper plates, and a lead wire to the pulse voltage application first power source 4 was attached to the copper plate. The second cell 2 with reduced CO concentration has the same structure, and the potentiostat (manufactured by Hokuto Denko) and the function generator (manufactured by Hokuto Denko) are used for the pulse voltage application first power supply 4 and the pulse voltage application second power supply 5, respectively. A combination of these was used.
[0021]
For CO monitor cell 3, PEFC with a rod-shaped electric heater 25cm ² However, in order to allow a large flow rate to flow, the depth of the flow path was set to 5 times the normal (1.5 mm). An anode using a catalyst in which a platinum-ruthenium alloy is supported on carbon is 5 cm × 5 cm (25 cm). ² ) With a 1 cm × 1 cm (1 cm) cathode made of carbon carrying platinum. ² ), With Nafion 112 (manufactured by DuPont) sandwiched between both electrodes, overlaid with a catalyst layer, and hot-pressed for an effective area of 1 cm ² Class electrode / membrane assembly was prepared. The CO monitor cell 3 was connected to a DC power supply 9 and an ammeter 6, and the signal (voltage output) of the ammeter 6 was used as a trigger for starting the function generator of the pulse voltage application second power supply 5.
[0022]
FIG. 3 is a graph for explaining the operation of the CO concentration reducing apparatus according to this embodiment. In the figure, 23 is a broken line indicating the CO concentration at the gas inlet, and 24 is a solid line indicating the CO concentration at the outlet of the CO-reduced second cell anode. As a gas simulating the reformed fuel gas, a mixed gas of carbon monoxide 400 ppm, carbon dioxide 25% and hydrogen 75% is used and humidified with an external humidifier kept at 80 ° C. and shown in FIG. Was supplied to a CO concentration reduction apparatus. The amount of gas passed is 500 mA / cm ² 225cm in terms of 70% hydrogen utilization ² X 40 cells.
[0023]
As shown in FIG. 3, in the CO-reduced first cell 1, the CO concentration is drastically reduced by continuous pulse potential application, but untreated carbon monoxide gradually accumulates in the CO-reduced second cell 2, Furthermore, the amount of carbon monoxide that could not be adsorbed in the second CO-reduced cell 2 gradually increased, and when one minute passed, the concentration of carbon monoxide at the outlet of the second CO-reduced cell 2 increased to a level exceeding 100 ppm. is doing. Correspondingly, the current value of the CO monitor cell 3 increases, the activation trigger 2 is applied to the function generator of the pulse voltage application second power source 5, and the pulse voltage is applied to the CO reduction second cell and is adsorbed. Carbon monoxide is wiped out. This repetition continues stably at an interval of about 1 minute. During this time, the CO concentration at the second cell anode outlet temporarily exceeds 100 ppm, but on average it is about 40 ppm, compared with 400 ppm at the treated gas inlet. It was reduced to 1/10.
[0024]
When this apparatus was used to process a reformed fuel gas containing 1% carbon monoxide, the CO concentration could be reduced to 400 ppm. Therefore, when another cell was added between the CO-reduced first cell 1 and the CO-reduced second cell 2, and the pulse voltage was continuously applied to the added CO-reduced cell, the CO concentration of 1% was obtained. The average CO concentration was 40 ppm, and the maximum CO concentration was 100 ppm.
[0025]
Thus, at least one of the CO-reduced first cell 1 and the CO-reduced second cell 2 may be composed of a plurality of cells, and the same effect can be obtained even in a stack in which several cells are stacked. Furthermore, at least one of the CO-reduced first cell 1 and the CO-reduced second cell 2 may be composed of a series connection body of a plurality of cells.
In short, it is intended to reduce the amount of wasted power by dividing the CO reduction cell into a cell that applies a pulse voltage steadily and a cell that applies a pulse voltage non-steadily. Various applications can be considered within the scope of the present invention.
[0026]
Note that FIG. 3 illustrates the case where the CO concentration in the supplied gas to be treated is constant. However, even when the CO concentration varies greatly, the voltage applied to the CO-reduced second cell 2 in accordance with the signal of the monitor cell 3 Therefore, the amount of electrolysis can always be kept to the minimum necessary, and the CO concentration can be reliably reduced without wasting power.
[0027]
Here, this CO concentration is reduced in a fuel cell power generation system that generates power by supplying the reformed gas reformed by the reformer to the fuel electrode of the fuel cell and supplying the oxidant gas to the oxidant electrode of the fuel cell. A case where the apparatus is applied will be described.
FIG. 4 is a configuration diagram of a polymer electrolyte fuel cell power generation system including a CO concentration reducing device according to the present embodiment. In the figure, 19 is a fuel reformer, 20 is a CO concentration reducing device according to this embodiment, 21 is a polymer electrolyte fuel cell, and 22 is a fuel inlet. The CO concentration reducing device 20 is connected to the fuel cell power generation system so that the gas inlet 7 to be processed is connected to the reformer 19 and the outlet 11 is connected to the gas supply port of the fuel electrode. Then, the reformed gas reformed by the reformer 19 is supplied to the CO concentration reducing device 20, and the CO contained in the reformed fuel gas when passing through the CO concentration reducing device 20 is as described above. It is removed and introduced into the fuel electrode. The CO concentration of 1% is the carbon monoxide concentration immediately after the reformer 19, and the average CO concentration of 40 ppm and the maximum of 100 ppm is the CO concentration allowed by the PEFC 21.
[0028]
As described above, if the CO concentration reduction device 20 according to the present embodiment is arranged between the reformer 19 and the PEFC 21, the poisoning of the catalyst in the fuel cell can be achieved without using the conventional CO selective oxidation device. Suppressed and stable power generation. Further, since air is not added to the reformed fuel gas, hydrogen is not wasted due to oxygen in the air, and the hydrogen concentration is not diluted with nitrogen in the added air. Thereby, the big effect that total power generation efficiency raises about 2% is acquired. Furthermore, since a voltage is applied to the CO-reduced second cell 2 in accordance with the signal from the monitor cell 3, the amount of electrolysis can always be kept to the minimum necessary even when the CO concentration fluctuates greatly, and power is wasted. In addition, the CO concentration can be reliably reduced. Therefore, a fuel cell power generation system with high characteristics and high output can be obtained.
[0029]
Embodiment 2. FIG.
Next, a CO concentration reduction apparatus according to Embodiment 2 of the present invention will be described. The basic configuration of the CO concentration reducing apparatus according to the present embodiment is the same as that shown in FIG. 1, but the interval at which the pulse voltage is applied to the CO reducing second cell 2 is within a predetermined range, for example, 10 seconds to 60 seconds. A circuit for controlling the period of the pulsed voltage of the CO-reducing first cell 1 was incorporated so as to be within the range. As this circuit, a combination of a potentio galvanostat and a function generator is used, but a DC pulse voltage generator may be used.
That is, when the interval of applying the pulsed voltage to the CO-reduced second cell 2 becomes smaller than, for example, 10 seconds, the pulse-like voltage application cycle of the CO-reducing first cell 1 is doubled, for example. Increases the time required for the CO-reduced first cell 1 twice, and when the interval of applying the pulsed voltage to the CO-reduced second cell 2 exceeds 60 seconds, for example, the pulse-like form of the CO-reduced first cell 1 For example, the voltage application period is halved, and the time required for the pulsed voltage to be applied to the CO-reducing first cell 1 is halved.
[0030]
In such a configuration, the amount of gas to be treated having a CO concentration of 1% to be supplied is set to 500 mA / cm. ² 225cm in terms of 70% hydrogen utilization ² × 225cm from 10 cells ² When the change was repeated for × 40 cells, when the cell voltage was reduced to 10 cells, the period of the pulsed voltage of the CO-reduced first cell 1 was halved and increased to 40 cells. The period of the pulse voltage of the first CO reduction cell doubled, but the average CO concentration of 40 ppm was maintained. On the other hand, when the same test is performed with the first embodiment maintained, when the number of cells is increased to 40 cells, the electrolysis of the CO-reduced second cell 2 becomes frequent, and the carbon monoxide concentration is increased. A situation exceeding 200 ppm appeared.
[0031]
【The invention's effect】
As described above, according to the first invention, the CO-reduced first cell and the CO-reduced second cell in which the pair of gas diffusion electrodes are disposed on both surfaces of the ion-conductive electrolyte membrane via the catalyst layers, respectively. , A voltage-applied first power source and a voltage-applied second power source for independently applying a pulsed voltage to the CO-reducing first cell and the CO-reducing second cell, and supplying hydrogen gas containing carbon monoxide to the anode of the CO-reducing first cell After that, the means for flowing the anode of the CO-reduced second cell, the cathode of the CO-reduced second cell, the cathode of the CO-reduced first cell, and the CO concentration monitoring means for monitoring the CO concentration at the anode outlet of the CO-reduced second cell The pulsed voltage is continuously applied to the first CO-reduced cell using the voltage application first power source, and the second CO-reduced cell is subjected to voltage application based on the signal from the CO concentration monitoring means. A pulsed voltage is intermittently applied using a power source, and carbon monoxide is reacted with moisture at the anodes of the first CO reduction cell and the second CO reduction cell to convert it into carbon dioxide, protons, and electrons. Since hydrogen is generated from protons and electrons at the cathode of one cell and the second CO-reduced cell, even when CO is selectively oxidized by electrolysis and the CO concentration changes greatly, hydrogen and power are consumed wastefully. Therefore, the CO concentration can be reduced efficiently and reliably.
[0032]
According to the second invention, in the first invention, the period of the pulsed voltage of the CO-reduced first cell is controlled so that the interval of applying the pulsed voltage to the CO-reduced second cell is within a predetermined range. Therefore, the CO concentration can be reduced more stably.
[0033]
According to the third aspect of the invention, fuel cell power generation is performed in which the reformed fuel gas reformed by the reformer is supplied to the fuel electrode of the fuel cell and the oxidant gas is supplied to the oxidant electrode of the fuel cell to generate power. In the system, an apparatus for reducing the carbon monoxide concentration in the hydrogen gas containing carbon monoxide according to the first or second invention is disposed in the reformed fuel gas path between the reformer and the fuel electrode. Since the carbon monoxide concentration contained in the reformed fuel gas is reduced and supplied to the fuel electrode, the CO concentration in the reformed fuel gas is reduced, and the CO poisoning of the catalyst on the fuel electrode side is reduced. And can generate power with high characteristics.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a configuration of a CO concentration reducing apparatus according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration of a first CO concentration reduction cell according to the first embodiment.
FIG. 3 is a graph for explaining the operation of the CO concentration reducing apparatus according to the first embodiment.
4 is a diagram showing a configuration of a fuel cell power generation system including a CO concentration reducing apparatus according to Embodiment 1. FIG.
FIG. 5 is a diagram schematically showing a configuration of a CO concentration reducing device according to Conventional Example 1.
6 is a diagram schematically showing a configuration of a CO concentration reducing apparatus according to Conventional Example 2. FIG.
[Explanation of symbols]
1 CO reduction 1st cell, 2 CO reduction 2nd cell, 3 CO monitor cell, 4 pulse voltage application 1st power supply, 5 pulse voltage application 2nd power supply, 6 ammeter, 7 gas inlet, 8 gas piping, 9 DC Power supply, 10 CO-treated gas connection, 11 CO-treated gas outlet, 12 solid polymer electrolyte membrane, 13 anode channel plate, 14 cathode channel plate, 15 anode, 16 cathode, 17 anode gas channel, 18 cathode gas Channel, 19 Fuel reformer, 20 CO concentration reducing device according to Embodiment 1, 21 Polymer electrolyte fuel cell, 22 Fuel inlet, 29 First CO selective oxidizer, 30 Second CO selective oxidizer, 31 Gas to be treated inlet, 32 connecting pipe, 33 CO treated gas outlet, 34 first CO selective oxidizer air inlet, 35 second CO selective oxidizer air inlet, 41 CO reduction cell 44 Power supply for applying pulse voltage.

Claims (3)

A CO reduced first cell, a CO reduced second cell, a CO reduced first cell, and a CO reduced second cell in which a pair of gas diffusion electrodes are respectively disposed on both surfaces of an ion conductive electrolyte membrane via a catalyst layer. A voltage-applied first power source and a voltage-applied second power source for independently applying a pulsed voltage, and supplying hydrogen gas containing carbon monoxide to the anode of the CO-reducing first cell, then the anode of the CO-reducing second cell, CO reducing A means for flowing the cathode of the second cell, the cathode of the CO-reduced first cell in that order, and a CO concentration monitoring means for monitoring the CO concentration at the anode outlet of the CO-reduced second cell, and applying a voltage to the CO-reduced first cell A pulsed voltage is continuously applied using the first power source, and the pulsed voltage is intermittently applied to the CO-reduced second cell using the voltage applied second power source based on the signal from the CO concentration monitoring means. And carbon monoxide reacts with moisture at the anodes of the CO-reduced first cell and the CO-reduced second cell to convert them into carbon dioxide, protons and electrons, and at the cathodes of the CO-reduced first cell and the CO-reduced second cell. An apparatus for reducing the concentration of carbon monoxide in hydrogen gas containing carbon monoxide, wherein hydrogen is generated from protons and electrons. 2. The carbon monoxide according to claim 1, wherein the period of the pulsed voltage of the CO-reduced first cell is controlled so that the interval at which the pulsed voltage is applied to the second CO-reduced cell falls within a predetermined range. For reducing the carbon monoxide concentration in hydrogen gas containing hydrogen. In a fuel cell power generation system for generating power by supplying the reformed fuel gas reformed by the reformer to the fuel electrode of the fuel cell and supplying the oxidant gas to the oxidant electrode of the fuel cell, the reformer and An apparatus for reducing the concentration of carbon monoxide in the hydrogen gas containing carbon monoxide according to claim 1 or 2 is disposed in the path of the reformed fuel gas with the fuel electrode, and the reformed fuel gas A fuel cell power generation system characterized in that the concentration of carbon monoxide contained therein is reduced and supplied to the fuel electrode.

Images