JPS6134865A - Fuel cell power generating system - Google Patents

Abstract

PURPOSE:To reform a plurality of fuels without replacing catalysts by placing a plurality of catalysts having different catalytic actions in a reformer which reforms fuel to a gas suitable for cell reaction. CONSTITUTION:Catalysts 32 placed in a cooling passage 34 inside a cell stack 10 consists of the mixture of two or more different catalysts. The mixed fuel 46 is vaporized and heated with a heat exchanger 48, and fed to the passage 34, and reformed by catalysts 32 to form reformed gas 44 which contains a large amount of hydrogen and carbon monoxide. The gas 44 is supplied to fuel chambers 28 and 30 to perform cell reaction in the fuel electrodes 24 and 26, then exhaust gas 52 is exhausted to the outside. By this process, partial oxidation and/or steam reforming are conducted as a fuel reforming means. Therefore, a plurality of fuels are reformed without replacing catalysts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel cell power generation device, and particularly relates to an internal reforming fuel cell in which fuel is reformed in a cooling passage having a catalyst provided within the cell body. Regarding the power generation device used.

[Background of the invention]

The fuel used in fuel cells needs to be reformed into a gas suitable for cell reactions. Generally, reforming of this gas is performed through a catalyst, and the catalyst varies depending on the type of fuel.

By the way, conventionally, internal reforming fuel cells and power generation equipment are ENERGY RESEARCHHC0RPOR.
ATION+7JP, S, FAT11! Technical document “INTERNAL REFORMING FORN” by L et al.
ATURAL GAS FUHLED 0LTEN c
AuBosAra F (IELCELLS" (Document No. GRI-8010126, 1981). The fuel cell system in this document does not consider any internal reforming for fuel diversification in the fuel cell system. No. For this reason.

If multiple different fuels are used, should the battery stack, which is the battery main body, be disassembled and the catalyst replaced, or should a new passage be created to hold the catalyst?

Another problem was that the fuel cell had to be replaced.

[Purpose of the invention]

An object of the present invention is to provide a fuel cell power generation device that can reform a plurality of fuels without replacing catalysts.

[Summary of the invention]

In the present invention, a plurality of catalysts having different catalytic actions are mixed in a reforming section that reformes fuel into a gas suitable for cell reactions, and two
The structure is such that each of more than one type of fuel can be reformed.

[Embodiments of the invention]

Preferred embodiments of the fuel cell power generation device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 schematically shows an embodiment of a fuel cell power generation device according to the present invention, and shows an outline of a molten carbonate type fuel cell power generation device using molten carbonate as an electrolyte. . In FIG. 2, a battery stack 10 which is a battery main body
is an oxidizing chamber 20.22 in which an oxidizing agent such as air or oxygen is supplied to one side of the electrolyte 12 through oxidizing electrodes 16 and 18.
A fuel chamber 28,30 is formed on the other side of the electrolytes 12, 14 via the fuel electrodes 24, 26, and a cooling passage 34 holding a catalyst 32 is provided between the oxidizer chamber 22 and the fuel chamber 28. It has a similar structure, and is made up of layers of layers. At one end of the oxidizing agent chamber 20.22, an oxidizing agent such as air or oxygen exchanges heat! At #38, it is supplied after being warmed by the heat medium 40, and the exhaust gas 42 is discharged from the other end. The reformed gas 44 supplied to one end side of the fuel chamber 2, 8, 30 is heated by a heat medium 50 in a heat exchange process [48].

It is supplied to the cooling passage 34 and reformed, and exits as exhaust gas 52 from the other side of the fuel chamber 28,30.

The mixed fuel 46 includes a hydrocarbon fuel 56 such as methane or propane, or a fuel 58 such as methanol, supplied via a fuel switching device 54, and an oxidizing agent 36 supplied via a stop valve 60 and a switching device W62. Or a mixture with pure water 64.

The catalyst 32 held in the cooling passage 34 includes two or more types of catalysts 32a having different catalytic actions, as shown in FIG.
It consists of a mixture of g 32 b y 32 c. These catalysts include, for example, Ni-based catalysts and Cu-8t
It consists of a Zn-Fe, O, system catalyst, and in addition Cu-Nt, CuO-Zn0-An, 0
．． , Cu-Zn and pt-based catalysts can be used.

The operation of the embodiment configured as described above is as follows. The fuel 56 is a hydrocarbon fuel such as methane or propane, and the other fuel 58 is methanol. On the other hand, the oxidizing agent 36 such as air or oxygen or the pure water 64 is switched and supplied by the switching device 62 as necessary, and is combined with the fuel 56 or the fuel 58 via the stop valve 60.
A mixed fuel 46 is obtained. The mixed fuel 46 is vaporized in a heat exchanger 48 using a heat medium 50 as a heat source, and is heated to a temperature of 6.
After being heated to about 50 to 700°C, the battery stack 10
The gas is sent to the cooling passage 34 in the interior and reformed by the catalyst 32 to become a reformed gas 44 containing a large amount of hydrogen and carbon oxide. The reformed gas 44 is sent to the fuel chambers 28 and 30, undergoes an electrode reaction at the fuel electrodes 24 and 26, and is discharged to the outside as exhaust gas 52. The oxidizing agent 36 is applied to a heat exchanger 38 using a heat medium 40 as a heat source at a temperature of 65% below the battery temperature.
The temperature is raised to about 0 to 700° C., and the gas is sent to the oxidizer chamber 20° 22, where an electrode reaction occurs at the oxidizing electrodes 16 and 18, and the gas is discharged to the outside as exhaust gas 42.

According to this embodiment, since a plurality of catalysts 32a, 32b, and 32c having different catalytic actions are held in the cooling passage 34, partial oxidation, steam reforming, or both can be used as means for reforming the fuel. I can do it. Therefore,
This has the effect that the energy of the power generation device can be flexibly controlled as needed. Furthermore, since the reforming of the mixed fuel 46 in the cooling passage 34 is an endothermic reaction,
The temperature rise of the battery stack 10 is suppressed due to the endothermic effect of the internal reforming reaction, and the residual heat of the battery is used for the reforming reaction, which improves the thermal efficiency of the system, and eliminates the need for a reformer, which improves equipment efficiency. This has the effect of reducing costs.

In the embodiment, a plurality of catalysts 32 in the cooling passage 34
a, 32b, and 32c are shown in the form of particles and filled in the cooling passage 34 in a dispersed state.
It may be configured as shown in the figure.

That is, the plurality of catalysts 32a, 32b shown in FIG.

Reference numeral 32c shows the case where the particles are sprayed and adhered to the inner wall of the cooling passage 34 by a method such as thermal spraying. By attaching the catalysts 32 a, 32 b, and 32 c to the wall surface of the cooling passage 34 in this manner, the efficiency of the endothermic reaction can be further increased.

FIG. 4 shows another embodiment of the present invention, in which parts that are the same as those in FIG. 2 are given the same reference numerals, and parts that are different from those in FIG. do. In this embodiment, a heat exchanger 66 is installed to preheat the mixed fuel 46 in order to use the amount of heat contained in the exhaust gas 42 discharged from the oxidizer chamber 20.degree. 22. The mixed fuel 46 is transferred to the heat exchanger 6
6, it is preheated by exhaust gas 42 and then introduced into a heat exchanger 48. As a result, in addition to the effect of the embodiment shown in FIG. 1, the amount of heat that must be held by the heat medium 50 is reduced by the amount of heat transferred from the exhaust gas 42 to the mixed fuel 46, which further improves the thermal efficiency of the entire power generation device. This has the effect of improving.

FIG. 5 shows that instead of performing heat recovery using the exhaust gas 42 exiting from the oxidation chamber 20, 22 shown in the embodiment of FIG. 4, exhaust gas 52 exiting from the fuel chamber 28. An example of performing collection is shown. By guiding the exhaust gas 52 exiting the fuel chamber 28, 30 to the heat exchanger 66 and exchanging heat with the mixed fuel 46, the thermal efficiency of the entire power generator is improved compared to the embodiment shown in FIG.

FIG. 6 is an improved version of the embodiment shown in FIG. A description will be given of the parts including the parts that are different from FIG. 4. In this embodiment, the exhaust gas 52 coming out of the fuel chamber 28° 30 is transferred to the burner section 68 newly attached to the heat exchanger 48.
The oxidizing agent 70 is used as a fuel and the oxidizing agent 70 is a branched oxidizing agent 36 such as air or oxygen, which is introduced into the burner section 68 via a flow rate regulating valve 72 and released to the outside as exhaust gas 74. let That is, the mixed fuel 46 is heated to a temperature of approximately 6i0 to 700° C., which is the operating temperature of the battery stack 10, by the combustion heat of the exhaust gas 52.

As a result, the heat medium 50 shown in FIG. 4 is not required, and the exhaust gas 52 from the fuel cell in the burner section 68 is used, so that the thermal efficiency of the entire power generation device can be improved more than the embodiment shown in FIG. It has the effect of being able to

FIG. 7 shows a further improvement of the embodiment shown in FIG. In this embodiment, the heat of the exhaust gas 74 released from the burner section 68 is to be used effectively, and a heat exchanger 76 is installed before the oxidizing agent 36 passes through the heat exchanger 38 whose heat source is the heat medium 40. The heat of the exhaust gas 74 is transferred to the oxidizer 3.
6 is supplied. This has the added effect of further improving the overall thermal efficiency.

FIG. 8 shows an improvement of the embodiment shown in FIG. 7, with emphasis placed on keeping the reformed gas 44 supplied to the battery stack 10 warm. In this embodiment, the exhaust gas 74 discharged from the burner section 68 is
However, a heat exchanger 78 is installed to be used as a heat source for keeping the reformed gas 44 warm, and heat is exchanged with the reformed gas 44 in a heat exchanger 87B. As a result, the temperature of the reformed gas, which has been reformed and whose temperature has been lowered, can be maintained at about the battery operating temperature, thereby stabilizing the battery performance and reducing temperature changes, which is thought to extend the battery life.

FIG. 9 shows the embodiment of FIG. 8 with an external reformer added. In this embodiment, when the reformed gas reformed in the cooling passage 34 of the battery stack 10 is not completely reformed, an external reformer 8 newly installed next to the heat exchanger 78
0 increases the reforming rate and supplies the reformed gas containing more hydrogen and carbon oxide to the fuel chamber 28.30. Note that a burner section 84 is provided in the external reformer 84 in order to heat the external reformer 80. Burner part 8
The oxidizing agent 86 of No. 4 is obtained by branching from the oxidizing agent 36, and is introduced into the burner section 84 through a flow rate regulating valve 88. on the other hand,
The fuel 90 in the burner section 84 is obtained by branching off the exhaust gas 52 from the fuel chamber 28.30.
It is supplied by passing the . The fuel 90 in the burner section 84 is auxiliary fuel 1 obtained by passing auxiliary fuel 96 and 98 through flow rate regulating valves 100 and 102, respectively.
04 and fuel 92 may be combined.

This ensures that the reformed gas 82 sent into the fuel chamber 28.30 becomes a fuel with a high reforming rate, that is, a high concentration of hydrogen and carbon oxide, which has the effect of improving the power generation performance of the cell stack 10. .

The above discussion has been limited to molten carbonate fuel cell systems, but even in solid oxide fuel cell systems where the cell operating temperature is high, hydrocarbon gases or liquid fuels such as naphtha can be used as fuel, and each can be effectively used. However, it is possible to carry out internal reforming in the presence of a reforming catalyst, and the present invention is not limited to a molten carbonate fuel cell system. It can also be applied to an external reforming type fuel cell power generation device.

〔Effect of the invention〕

As described above, according to the present invention, each of a plurality of fuels can be reformed without replacing the catalyst in the fuel reforming section.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the state of the catalyst filled in the cooling passage of an internal reforming fuel cell according to an embodiment of the present invention, and FIG. FIG. 3 is an explanatory diagram of another embodiment of a method for holding a plurality of catalysts in a cooling passage, and FIG. 4 is another embodiment of the fuel cell power generation device according to the present invention. Fig. 5 is a schematic block diagram showing an example of preheating the mixed fuel using exhaust gas from the oxidation chamber; Fig. 5 is a schematic block diagram showing an example of preheating the mixed fuel using exhaust gas from the fuel chamber; 7 is a schematic diagram of an embodiment in which exhaust gas from the fuel chamber of the fuel cell power generation device according to the invention is used as fuel for a heat exchanger that heats a mixed fuel. FIG. 10...Battery stack, 12.14 ...electrolyte, 1
6゜18...Oxidizing electrode, 20,22...Oxidizer chamber, 2
4゜26... Fuel electrode, 28, 30... Fuel chamber, 32
, 32a. 32b, 32cm catalyst, 34-...cooling passage, 44°8
2...Reformed gas, 46...Mixed fuel, 56.58.
...Fuel, 74...Pure water.

Claims (1)

[Scope of Claims] 1. A battery in which a plurality of cell units are stacked, each consisting of a fuel chamber provided on one side of the electrolyte via a fuel electrode, and an oxidizer chamber provided on the other side of the electrolyte via an oxidizing electrode. A fuel cell power generation device comprising: a main body; a reforming section that uses a catalyst to reform fuel into a reformed gas that is supplied to the fuel chamber; and an oxidizer supply device that supplies an oxidizer to the oxidizer chamber. . A fuel cell power generation device, wherein the catalyst in the reforming section includes a plurality of catalysts having different catalytic actions. 2. The fuel cell power generation device according to claim 1, wherein the reforming section is a cooling passage having the catalyst provided in the cell main body.