JPH076781A - Phosphoric acid fuel cell power generating device - Google Patents

Abstract

PURPOSE:To obtain a fuel cell power generating device, which can reduce the lowering of the voltage due to ammonia included in the fuel gas and which can reduce shortening of the lifetime. CONSTITUTION:A phosphoric acid fuel cell generating device 1 is provided with an ammonia eliminating device 2, and also provided with a supply passage 91a for supplying the fuel gas from a fuel reforming unit 6 to the ammonia eliminating device 2 and a supply passage 91b for supplying the fuel gas from the ammonia eliminating device 2 to a fuel cell main body 5. The ammonia eliminating device 2 houses acid group such as phosphoric acid, sulfuric acid, and hydrochloric acid as the ammonia eliminating agent, and the fuel gas is passed through this ammonia eliminating agent, and the ammonia included in the fuel gas is neutralized by the acid as the ammonia eliminating agent, and eliminated selectively. The fuel gas, which is passed through the ammonia eliminating device 2 to reduce the ammonia density thereof, is supplied to a fuel electrode of the fuel electrode main body 5 through the supplying passage 91b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphoric acid fuel cell power generator, and to an improved structure for reducing the content of ammonia present in fuel gas.

[0002]

2. Description of the Related Art A phosphoric acid fuel cell power generator comprises a matrix supporting phosphoric acid, and a fuel electrode and an oxidant electrode sandwiching this matrix to generate direct current electricity by receiving supply of fuel gas and oxidant gas. Unit cell
It is a power generation device including a fuel cell main body including a laminate of a plurality of laminated unit cells, and a device that supplies fuel gas and oxidant gas to the fuel cell main body. In a phosphoric acid fuel cell power generator, a gas containing a high concentration of hydrogen obtained by steam reforming a hydrocarbon-based fuel such as natural gas or naphtha is used as the fuel gas, and the oxidant gas is used as the oxidant gas. An apparatus using reaction air supplied by an air supply means is widely known.

FIG. 4 is a system configuration diagram showing a system configuration of a main part of a conventional example of such a phosphoric acid fuel cell power generator. In FIG. 4, 9 is a phosphoric acid fuel cell power generator including a fuel cell main body 5, a fuel reformer 6, and an air supply means 8. The fuel cell main body 5 has a pair of porous matrixes having a matrix supporting phosphoric acid as an electrolyte, and a fuel gas flow passage and an oxidant gas flow passage that sandwich the matrix and through which the fuel gas and the oxidant gas flow, respectively. It is provided with a unit cell stack in which a plurality of unit cells including a fuel electrode and an oxidizer electrode, which are gas diffusion electrodes, are stacked. The unit cell of the fuel cell main body 5 is generally operated while maintaining its temperature at about 200 ° C. in order to operate the device with high efficiency.

The fuel reformer 6 is a device that is supplied with a hydrocarbon-based raw material fuel such as natural gas or naphtha from the fuel supply means 7 and reforms hydrogen into a fuel gas containing a high concentration of hydrogen. The fuel gas obtained in the fuel reformer 6 is supplied to the fuel electrode of the fuel cell body 5 via the fuel gas supply passage 91. On the other hand, the reaction air, which is an oxidant gas, is supplied to the oxidant electrode of the fuel cell main body 5 from the air supply means 8 which is an air compressor, for example, through the reaction air supply passage 92. The fuel gas and the reaction air contribute to the generation of direct current electricity by performing the already known chemical reactions in the fuel cell main body 5, and become the so-called off-gas in which hydrogen or oxygen is consumed and are discharged from the fuel cell main body 5. To be done.

When starting the operation of the phosphoric acid fuel cell power generator 9, the temperature of the fuel reformer 6 is raised to its reaction temperature while purging the fuel reformer 6 with inert nitrogen. When the temperature is raised to a predetermined reaction temperature, the nitrogen purge is stopped, the supply of steam to the fuel reformer 6 is started, and the supply of the raw material fuel is started after a lapse of a certain time. The raw material fuel mixed with water vapor (hereinafter sometimes abbreviated as reforming raw material) is
Due to the function of the fuel reforming catalyst housed in the fuel reformer 6, hydrogen is reformed into a fuel gas containing a high concentration. The fuel cell main body 5 generates direct current power in response to the supply of the fuel gas and the reaction air.

The DC power generated by the fuel cell body 5 is supplied to an electric load device (not shown) as it is or after being converted into AC power by a DC / AC converter (not shown) as necessary. .

[0007]

In the phosphoric acid fuel cell power generator according to the above-mentioned conventional technique, it is possible to generate DC power from the hydrocarbon-based raw material fuel and air, but the following problems occur. Existing. That is, the catalyst for fuel reforming contained in the fuel reformer 6 may contain a small amount of ammonia in the manufacturing process. Ammonia contained in this catalyst is removed by applying heat treatment or the like to the reformer catalyst, but it is not always possible to completely remove this ammonia. The ammonia contained in this catalyst is
It will be mixed in the fuel gas supplied from the fuel reformer 6. Immediately after starting the supply of the raw material fuel to the fuel reformer 6, the nitrogen used for purging still remains, reacting with the hydrogen generated by reforming the reforming raw material, and Ammonia having a concentration of about [ppm] to several tens [ppm] may be generated and contained in the fuel gas. Further, when nitrogen is contained as an impurity in the reforming raw material, the fuel gas contains ammonia having a concentration according to the content of the nitrogen.

Ammonia contained in the fuel gas in this manner is temporarily or continuously supplied to the fuel cell main body 5 during operation of the phosphoric acid fuel cell power generator 9. This ammonia reacts with the phosphoric acid, which is the electrolyte present in the fuel electrode, the oxidizer electrode, and the matrix, to form ammonium phosphate. Since phosphoric acid, which is an electrolyte, is consumed in the production of ammonium phosphate, the amount of phosphoric acid in the fuel cell main body 5 becomes insufficient, which lowers the generated voltage of the fuel cell main body 5 or shortens its life. May be shortened.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is a degree of poisoning such as reduction of generated voltage and shortening of life due to ammonia contained in fuel gas. It is to provide a fuel cell power generation device capable of reducing

[0010]

SUMMARY OF THE INVENTION In the present invention, the above-mentioned objects are: 1) a fuel cell main body for generating direct-current power by supplying fuel gas and oxidant gas to a fuel electrode and an oxidant electrode, respectively; In a phosphoric acid fuel cell power generator including a fuel reformer for supplying a fuel gas containing hydrogen at a high concentration to a fuel electrode provided in the main body, the fuel gas between the fuel reformer and the fuel cell main body 2) The ammonia removal device is provided in the supply path, and 2) in the means described in 1 above, the ammonia removal device is configured to use an acid as a remover for removing ammonia, and 3) the 1) above. In the means described in the paragraph 1, the ammonia removing device is configured to use water as a remover for removing ammonia, and 4) in the means described in any one of 1 to 3 above. And a heating device is provided in the fuel gas supply path between the ammonia removing device and the fuel cell body, and 5) in the means described in any one of 1 to 2 above, The removal device is
This is achieved by a configuration in which a heating means for heating a removing agent for removing ammonia is installed integrally.

[0011]

In the present invention, the fuel gas supply passage between the fuel reformer and the fuel cell main body is provided with an ammonia removing device using an acid as a removing agent for removing ammonia. The ammonia contained in the fuel gas is selectively removed from the fuel gas by performing a neutralization reaction with the acid as the absorbent. As a result, the concentration of ammonia contained in the fuel gas supplied to the fuel cell body is reduced.

Further, the ammonia removing device using water as the removing agent is provided so that the ammonia contained in the fuel gas causes a dissociation reaction with water as the removing agent to dissolve in the water. To be done. However, hydrogen is
Since it hardly causes dissociation reaction with water, it is hardly dissolved in water. Therefore, the ammonia contained in the fuel gas is selectively removed by the water that is the remover. As a result, the concentration of ammonia contained in the fuel gas supplied to the fuel cell body is reduced.

By providing the heating device in the fuel gas supply path between the ammonia removing device and the fuel cell main body, heat is removed by the removing agent when flowing through the ammonia removing device. The cooled fuel gas is heated to the desired temperature. The ammonia removing device has a structure in which a heating means for heating a removing agent for removing ammonia is integrally provided, so that the removing agent is heated to a desired temperature by the heating means, and the fuel gas is removed by this heated removal. Flowing through the agent at least prevents it from suffering a drop in temperature.

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings. Embodiment 1; FIG. 1 is a system configuration diagram showing a system configuration of a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claims 1 to 3. In FIG. 1, the same parts as those in the phosphoric acid fuel cell power generator of the conventional example shown in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, reference numeral 1 is provided with an ammonia removing device 2 in addition to the phosphoric acid fuel cell power generator 9 of the conventional example shown in FIG. Phosphoric acid fuel cell power generation in which a supply passage 91a for supplying fuel gas from the reactor 6 to the ammonia removing device 2 and a supply passage 91b for supplying fuel gas from the ammonia removing device 2 to the fuel cell main body 5 are used. It is a device.

The ammonia removing device 2 uses acids such as phosphoric acid, sulfuric acid and hydrochloric acid as a removing agent for removing ammonia, and the removing agent is housed in a container having an acid resistant structure. This container is provided with an acid resistant pipe for introducing fuel gas and an acid resistant pipe for discharging fuel gas. The fuel gas is introduced into the container through this introducing pipe, and is supplied to the outside of the ammonia removing device 2 through the discharging pipe. The fuel gas introduced into the container flows through the removing agent. At that time, the ammonia contained in the fuel gas undergoes a neutralization reaction with the acid that is the removing agent, and the fuel gas is removed. It is selectively removed from the inside. The fuel gas whose ammonia concentration has been reduced by flowing through the ammonia removing device 2 in this way is supplied to the fuel electrode of the fuel cell body 5 via the supply passage 91b. This makes it possible to greatly reduce the degree to which the fuel cell main body 5 is poisoned by the ammonia present in the fuel gas.

In the above description of the first embodiment, the removing agent of the ammonia removing device 2 is assumed to be an acid, but the removing agent is not limited to this and may be water, for example. When acids such as phosphoric acid, sulfuric acid and hydrochloric acid are used as the above-mentioned removing agent, the ability to selectively remove ammonia from the fuel gas is excellent, but the acids are highly corrosive substances. Therefore, the devices used after the ammonia removing device 2 must be provided with a material / structure that can withstand the corrosiveness of the acids. That is, when phosphoric acid is used as the removing agent, phosphoric acid is used as the electrolyte in the fuel cell body 5, and the fuel cell body 5 and the devices following it are already made of materials and structures that can withstand the corrosiveness of phosphoric acid. Therefore, it is necessary to provide the ammonia removing device 2 and the supply passage 91b with a material / structure that withstands the corrosiveness of phosphoric acid. However, when using sulfuric acid, hydrochloric acid, or the like, which has a better ability to remove ammonia than phosphoric acid, as a removing agent, all of the various devices after the ammonia removing device 2 should be made of materials and structures that withstand these corrosive properties. It is necessary to prepare for it.

However, when water is used as the removing agent, by passing the fuel gas through the water, the ammonia contained in the fuel gas dissociates with the water and is dissolved in the water. It However, hydrogen hardly dissolves in water because it hardly causes a dissociation reaction with water. Therefore, the ammonia contained in the fuel gas is selectively removed by the water that is the remover. As a result, the concentration of ammonia contained in the fuel gas supplied to the fuel cell body can be reduced. Further, when water is used as the removing agent, it is not necessary to make the devices used after the ammonia removing device 2 an acid resistant structure because the water is a substance that is extremely corrosive.

Embodiment 2; FIG. 2 is a system configuration diagram showing a system configuration of a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claim 4. In FIG. 2, the same parts as those in the phosphoric acid fuel cell power generator according to the embodiment of the present invention corresponding to claims 1 to 3 shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 2, reference numeral 1A denotes a phosphoric acid fuel cell power generator 1 according to the present invention shown in FIG. 1, which additionally includes a heating device 3 between an ammonia removing device 2 and a fuel cell body 5. In place of the gas supply passage 91b, a supply passage 91c for flowing the fuel gas from the ammonia removing device 2 to the heating device 3,
This is a phosphoric acid fuel cell power generator in which a supply passage 91d for supplying a fuel gas from the heating device 3 to the fuel cell main body 5 is used.

Although the ammonia concentration of the fuel gas flowing through the ammonia removing device 2 is reduced, the temperature of the fuel gas becomes low because the heat is removed by the removing agent. However, as described above, the unit cell included in the fuel cell main body 5 needs to be operated while maintaining the temperature at about 200 [° C.] in order to operate the device with high efficiency, so that the fuel gas that has become low temperature When supplied to the unit cell as it is, it becomes difficult to maintain the temperature of the unit cell at the required temperature, which may cause a decrease in power generation efficiency. The heating device 3 is installed to cope with this. That is, the concentration of ammonia supplied from the ammonia removing device 2 is reduced, but the fuel gas having a low temperature is allowed to flow through the heating device 3 to, for example, the operating temperature of the unit cell included in the fuel cell main body 5. Is heated to about the same temperature as
It is supplied to the fuel cell main body 5 via d. As a result, as in the case of the first embodiment, the degree of poisoning of the fuel cell main body 5 due to the ammonia contained in the fuel gas is reduced, and the temperature of the unit cell is adjusted to a temperature suitable for highly efficient operation of the device. It is easy to maintain.

Embodiment 3; FIG. 3 is a system configuration diagram showing a system configuration of a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claim 5. In FIG. 3, a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claims 1 to 3 shown in FIG. 1, and an embodiment of the present invention corresponding to claim 4 shown in FIG. The same parts as those in the phosphoric acid fuel cell power generator according to the example are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 3, 1B is a heating type ammonia removing device 4 in place of the ammonia removing device 2 in the phosphoric acid fuel cell power generator 1 according to the present invention shown in FIG.
Is a phosphoric acid fuel cell power generator.
The heating-type ammonia removing device 4 is provided with a heating device as a heating means in a container that contains the removing agent, and holds the removing agent in the containing container at, for example, the operating temperature of the unit cell. Thereby, the heating type ammonia removing device 4
The fuel gas flowing therethrough is not heat-removed by the scavenger and does not reach a low temperature. Rather, the fuel gas is supplied to the fuel cell main body 5 via the supply passage 91b at a temperature desirable for highly efficient operation of the unit cell. To be done. Therefore, as in the case of the first embodiment, the problem that the fuel cell body 5 is poisoned by the ammonia contained in the fuel gas is solved, and the fuel gas is heated to a temperature suitable for highly efficient operation of the unit cell. Since it is no longer necessary to separately install the heating device, the configuration of the phosphoric acid fuel cell power generator 1B can be simplified.

[0023]

As described above, the present invention has the following effects due to the above-mentioned configuration. The degree of reduction in the voltage generated and the shortening of the life of the phosphoric acid fuel cell power generator due to poisoning from ammonia due to the reduction of the concentration of ammonia contained in the fuel gas supplied to the fuel cell body Can be reduced. In addition, the ammonia concentration of the fuel gas is reduced, and the temperature of the fuel gas is heated to about the same as the operating temperature of the unit cell provided in the fuel cell main body and supplied to the fuel cell main body, so that the degree of poisoning by ammonia is increased. It is possible to reduce the degree of decrease in the generated voltage of the phosphoric acid fuel cell power generator due to the decrease in the operating temperature of the unit cell. Furthermore, by using the ammonia removing device that integrally houses the heating device, it is possible to simplify the structure of the phosphoric acid fuel cell power generation device when obtaining the effect according to the above item.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a system configuration of a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claims 1 to 3.

FIG. 2 is a system configuration diagram showing a system configuration of a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claim 4;

FIG. 3 is a system configuration diagram showing a system configuration of a main part of a phosphoric acid fuel cell power generator according to an embodiment of the present invention corresponding to claim 5;

FIG. 4 is a system configuration diagram showing a system configuration of a main part of a conventional phosphoric acid fuel cell power generator.

[Explanation of symbols]

 1 Phosphoric Acid Fuel Cell Power Generator 1A Phosphoric Acid Fuel Cell Power Generator 1B Phosphoric Acid Fuel Cell Power Generator 2 Ammonia Removal Device 3 Heating Device 4 Heating Ammonia Removal Device 5 Fuel Cell Main Body 6 Fuel Reformer 91a Supply Channel 91b Supply route

Claims (5)

[Claims] 1. A fuel cell main body for generating direct-current power by supplying a fuel gas and an oxidant gas to a fuel electrode and an oxidant electrode, respectively, and a fuel containing a high concentration of hydrogen in a fuel electrode included in the fuel cell main body A phosphoric acid fuel cell power generator having a fuel reformer for supplying gas, characterized in that an ammonia removing device is provided in a fuel gas supply path between the fuel reformer and the fuel cell body. Phosphoric acid fuel cell power generator. 2. The phosphoric acid fuel cell power generator according to claim 1, wherein the ammonia removing device uses an acid as a remover for removing ammonia. 3. The phosphoric acid fuel cell power generator according to claim 1, wherein the ammonia removing device uses water as a remover for removing ammonia. 4. The phosphoric acid fuel cell power generator according to claim 1, wherein a heating device is provided in a fuel gas supply path between the ammonia removing device and the fuel cell body. And a phosphoric acid fuel cell power generator. 5. The phosphoric acid fuel cell power generator according to any one of claims 1 and 2, wherein the ammonia removing device is integrally provided with a heating means for heating an absorbent for removing ammonia. A phosphoric acid fuel cell power generator.