JP2807733B2 - Fuel cell generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel cell power generator, and more particularly, to a fuel cell power generator which is small in size and provides stable power for a long period of time.

(Prior Art) As a fuel for a fuel cell, a gaseous fossil fuel containing methane as a main component, such as methanol fuel or city gas or natural gas, is widely used. Methanol has the advantage of being easy to store and handle because it is a liquid, and has the advantage that the reformer has a simple structure.On the other hand, it has disadvantages such as the need to periodically refuel during continuous operation. Therefore, it is mainly used for remote islands where supply of city gas is difficult, or for small fuel cell power generators.

The operation of the fuel supply system will be described with reference to the configuration diagram of the fuel cell power generator in the case where methanol is used as the fuel shown in FIG.

Methanol M mixed at a predetermined ratio with water required for the reforming reaction is sent to the vaporizer 2 by the pump 1 and vaporized, and then enters the reformer 3. The reforming device 3 is filled with a reforming catalyst, and reforms methanol into a gas R rich in hydrogen. Since the reforming reaction is an endothermic reaction, the temperature of the catalyst is maintained at 200 to 300 ° C. by burning the exhaust gas S from the fuel electrode 5 of the fuel cell 4. By appropriately selecting the mixing ratio of methanol and water, the concentration of oxygen monoxide in the reformed gas R can be reduced to 1% or less. It is not necessary and can be led directly to the fuel electrode 5.

On the other hand, in the case of natural gas and city gas, fuel can be easily supplied only by gas piping and there is no need to store a large amount of fuel. I have.

The operation of the fuel supply system will be described with reference to the configuration diagram of the fuel cell power generation device using city gas as fuel shown in FIG.

The city gas A, which is the fuel, is mixed with the hydrogen-rich reformed gas R and enters the desulfurizer 6. Here, after removing sulfur in the form of hydrogen sulfide, it is mixed with steam H and enters the reformer 7. The fuel A is reformed into a gas Q rich in hydrogen by the reforming catalyst filled in the reformer 7. The amount of heat required for the reforming reaction is supplied by burning the exhaust gas S from the fuel electrode 5 of the fuel cell 4 together with the air O in a burner in the reforming apparatus, and the temperature of about 800 ° C. suitable for the reforming reaction is supplied. Have maintained. The gas Q leaving the reformer 7 contains about 15% of carbon monoxide, and if it is led to the fuel cell as it is, it will poison the platinum catalyst of the fuel electrode. For this reason, the carbon monoxide is passed through two stages of high and low temperature carbon monoxide converters 8 and 9 to reduce the carbon monoxide concentration to 1
% Or less. For the carbon monoxide converters 8 and 9, for example, an iron-chromium-based catalyst is used for high temperature, and a copper-zinc-based catalyst is used for low temperature. In some cases, only the low-temperature carbon monoxide converter 9 is installed. Although not shown in the figure, since the conversion reaction of carbon monoxide to carbon dioxide is an exothermic reaction, a heat exchanger is often provided before and after the converter.

(Problems to be Solved by the Invention) In the case of a fuel cell power generator using city gas as fuel, fuel can be easily supplied only by gas piping as described above, but on the other hand, in the case of a major earthquake, gas Distribution may be stopped, which is a serious problem when used in a power generation device that needs to supply power without interruption for a long time, for example, a power supply for communication. To solve this,
Although it is conceivable that methanol is used as a reserve fuel, the city gas and the methanol are greatly different in the reforming device including the reforming catalyst and the reforming temperature, so that two types of reforming devices must be provided. However, simply adding a fuel supply system for methanol that is not normally used in parallel as in the example shown in FIG. 5 not only hinders downsizing of the fuel cell power generator, but also increases the price of the apparatus. It is a big problem.

The present invention has been made in view of the above-described problems, and provides a fuel cell power generation device that is small in size, has a long service life and is inexpensive, and that switches fuel from city gas to methanol as a spare fuel without instantaneous interruption. With the goal.

(Means for Solving the Problems) In order to solve the above problems, the fuel cell power generator according to the present invention uses a reforming catalyst for city gas or natural gas provided downstream of a city gas or natural gas supply source. A reformer having a built-in reforming catalyst for methanol is arranged in series after the built-in reformer, and a fuel supply system in which a methanol supply source is connected to the methanol reformer is provided. When the gas supply is stopped,
The apparatus is characterized in that it comprises means for supplying methanol from the methanol supply source to the methanol reformer and means for heating the methanol reformer.

A second fuel cell power generator according to the present invention includes a reformer provided with a city gas or natural gas reforming catalyst provided downstream of a city gas or natural gas supply source, and a reformer downstream of the reformer. A fuel supply system in which a high-temperature carbon monoxide converter is arranged in series between a reformer that is connected in series and has a built-in methanol reforming catalyst to which a methanol supply source is connected; Alternatively, when the supply of the natural gas is stopped, a means for supplying methanol to the methanol reformer from the methanol supply source and a means for heating the methanol reformer are provided.

The present invention relates to a method in which a reformer incorporating a reforming catalyst for methanol is disposed in series with a reformer incorporating a reforming catalyst for city gas or natural gas, or a reformer incorporating a reforming catalyst for methanol is provided between these two reformers. And a fuel supply system in which a high-temperature carbon monoxide converter is arranged in series. As described above, in order to realize a fuel cell power generation device that can continue generating electricity even when the supply of city gas used as fuel during normal times is stopped due to a large earthquake, the conventional technology requires It was necessary to provide two fuel supply systems for gas or natural gas and for methanol. For this reason, the size of the fuel cell becomes larger, and it also increases the cost of the device. The present invention focuses on the fact that a catalyst similar to that of a low-temperature carbon monoxide converter in a city gas fuel supply system can be used as a methanol reforming catalyst, and a methanol reformer is used instead of the carbon monoxide converter. It is configured to be installed.

(Example) The present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a first embodiment of the present invention. In normal times, the city gas, which is the fuel, passes through the desulfurization device 6 in the same manner as described with reference to FIG. 4, and is reformed by the city gas reforming device 7 filled with the reforming catalyst C1 to be converted into hydrogen gas. It becomes rich reformed gas Q. The valves 23 and 24 are valves for adjusting the temperature of the reformer 7. The reformed gas Q enters the methanol reformer 3 filled with the reforming catalyst C2 through the valve 29.
Here, as the reforming catalyst C1, for example, Ni on an alumina support
O supported (e.g., 10 to 25 NiO on alumina support)
% Supported catalyst), or a catalyst obtained by adding one or more of an oxide of an alkali metal, an oxide of an alkaline earth metal, and an oxide of a rare earth element to a catalyst in which NiO is supported on an alumina carrier. In addition, as the reforming catalyst C2, for example, one or more of copper-zinc-based (for example, copper oxide containing 25 to 30% of copper) or copper-chromium-based, exhibits excellent effects. . Of course, the catalyst is not limited to these.

In the methanol reformer 3, carbon monoxide in the reformed gas Q is converted to carbon dioxide. Since the shift reaction is exothermic, the valves 25 and 26 are closed when city gas is used, and the burner of the methanol reformer 3 is not used.
If the temperature of the gas Q is too high, although not shown in the figure, by connecting a heat exchanger before the methanol reformer 3, the temperature of the reforming catalyst C2 can be adjusted to an appropriate temperature range of 150 to 300 ° C.
Can be In addition, by opening the valve 26 and allowing air to flow from the burner of the reformer, it is possible to easily maintain the catalyst temperature at an appropriate value without a heat exchanger, and to use it as an air preheater. it can.

When the supply of city gas, which is fuel in normal times, is stopped, the methanol fuel delivery pump 1 is started immediately, and methanol is supplied into the reformer via the valve 30 (the methanol fuel delivery pump 1 and the valve 30 constitutes means for supplying methanol). Methanol is instantaneously vaporized in the reformer 3 already heated by the heat of the shift reaction, passes through the reforming catalyst C2, is reformed, and becomes a hydrogen-rich gas R containing 1% or less of carbon monoxide, Fuel cell 4
To the fuel electrode 5. At the same time as switching to the methanol fuel, the valves 25 and 26 are opened to ignite the heating burner of the reformer 3 and supply the heat required for the vaporization and the reforming reaction (with the valves 25 and 26 and the heating burner). Means for heating the methanol reformer is configured). Since the temperature of the reformer 3 is in the operating temperature range in advance, no time is required for establishing the temperature, and the fuel can be switched without any instantaneous interruption.

FIG. 2 shows another embodiment of the present invention. In FIG. 1, a high-temperature carbon monoxide converter 8 filled with, for example, an iron-chromium catalyst is additionally provided between a city gas reformer 7 and a methanol reformer 3. The operation is the same as that of FIG. 1, but the thermal gradient between the operating temperature of the reformer for city gas 800 ° C. and the operating temperature of the fuel cell is approximately 200 ° C., and the conversion reaction of carbon monoxide is performed at a high temperature and It is implemented efficiently in two stages of low temperature. With such a configuration,
The concentration of carbon monoxide is much lower than in the first embodiment, and the life of the fuel electrode 5 and the reforming catalyst C2 of the fuel cell 4 can be made longer.

(Effects of the Invention) As is apparent from the above description, the present invention replaces a carbon monoxide converter, which is a component of a fuel supply system of a fuel cell using city gas as a normal fuel, with a methanol reformer. By adopting the configuration, it is possible to realize a small-sized and long-life fuel cell power generation device that can switch fuel from city gas to methanol, which is a spare fuel, without interruption and continue power generation. Further, at the time of a sudden increase in the load, the response delay of the city gas reforming system can be compensated by temporarily injecting the methanol fuel.

In the above embodiment, the case where city gas is used has been described, but it is clear that the case where natural gas is used is the same.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a block diagram of another embodiment of the present invention, FIG. 3 is a block diagram of a conventional fuel cell power generator using methanol as fuel, FIG. 4 is a configuration diagram of a conventional fuel cell power generator using city gas as fuel, and FIG.
The figure shows that city gas is used as normal fuel using conventional technology.
FIG. 2 is a configuration diagram of a fuel cell power generator using methanol as a reserve fuel. 3 ... methanol reformer, 4 ... fuel cell, 7 ... city gas reformer, A ... city gas source, M ... methanol source, V ... valve.

Claims (2)

(57) [Claims] 1. A reformer having a built-in reforming catalyst for city gas or natural gas, which is provided downstream of a supply source for city gas or natural gas, followed by a reformer having a built-in reforming catalyst for methanol in series. And a fuel supply system in which a methanol supply source is connected to the methanol reformer, and when supply of the city gas or natural gas is stopped, methanol is supplied from the methanol supply source to the methanol reformer. A fuel cell power generator comprising: means for supplying; and means for heating the methanol reformer. 2. A reformer provided with a city gas or natural gas reforming catalyst provided downstream of a city gas or natural gas supply source, and a reformer connected in series downstream of the reformer and methanol There is a fuel supply system in which a high-temperature carbon monoxide converter is arranged in series between a supply device and a reformer incorporating a methanol reforming catalyst, and the supply of the city gas or natural gas is stopped. A fuel cell power generator, comprising: means for supplying methanol from the methanol supply source to the methanol reformer when heated, and means for heating the methanol reformer.