JPH0636368B2 - Fuel cell power generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel cell power generator, and in particular, it operates at high temperature using molten carbonate or the like as an electrolyte and is equipped with an external reformer and an internal reformer. The present invention relates to a fuel cell power generation device in which a hydrogen gas separation device is provided in a pouch.

[Background of the Invention]

Conventional fuel cell power generators have been classified into an external reforming type reformer and an internal reforming type reformer.

The external reforming reformer literally produces hydrogen required in the anode chamber of the fuel cell power generator by a device other than the fuel cell power generator.

On the other hand, the internal reforming type room reformer directly or indirectly produces hydrogen in the anode chamber inside the fuel cell power generator. These two reformers have the following features when used in a fuel cell power generator.

In the external reforming type reformer, a reforming device is separately provided in addition to the cell stack which is the main body of the fuel cell power generation device. This reformer increases the reforming rate of fuel by 80%.
A so-called steam reforming apparatus, which obtains hydrogen by reforming fuel such as hydrocarbon with steam using a catalyst at a high temperature of about 0 ° C., is the mainstream. Since such a steam reformer has been used in the chemical industry for a long time, it has more achievements compared to the aged battery power generator, and it is technically and practically used to some extent in terms of reliability. Has reached a standard.

However, in the case of this external reforming type reformer, in addition to the problem of improving the life of the reforming catalyst, the reforming section and the power generation section have different configurations. Has a problem that the plant area becomes large and the apparatus configuration becomes complicated. In particular, since the reforming reaction is carried out under high temperature, the life of the catalyst is inevitably short, and therefore the catalyst must be replaced at regular intervals. Therefore, the operation of the fuel cell power generator may be stopped during the catalyst replacement period.

On the other hand, the internal reforming type reformer has a reforming section inside the anode chamber in the fuel cell power generator, so that it is possible to reduce the number of components compared to the external reforming type, and in terms of the configuration of the device. It has advantages such as simplification and compactness, and use of heat generated by a cell reaction at the time of reforming a fuel accompanied by an endothermic reaction so that the cell can be cooled at the same time. However, if the reforming reaction is to be performed only by the internal reformer, a battery reaction and a room reforming reaction have to be performed in the anode chamber, so that the anode chamber may become large and the battery main body may eventually become large. There is also a problem that the strength of the anode chamber must be increased in order to increase the size of the anode chamber. Furthermore, since it is difficult to regenerate and replace the reforming catalyst in the anode chamber, there is a problem in terms of improving the reliability and life of the fuel cell power generator in the entire apparatus.

The structure of the external reforming type process and the internal reforming type process described above is described in the document “Internal Reforming for Natural Gas”.
Fueled Carbonate Fuel Cells GRI-
80/0126, 1981, 12, Energy Research
"Corp, p, 2 to p, 8", the external reforming type reformer and the internal reforming type reformer have different positions and ideas from each other. The idea that the reformer reformer and the internal reformer reformer are combined is not shown at all. This fact indicates that the development of the external reforming type reformer follows the idea that the external reforming type reformer is positioned closer to practical use, and that the internal reforming type reformer has the simplest process. It is based on a different process in which its development is followed based on the idea that it can be realized by configuration.

As described above, the internal reforming type reformer and the external reforming type reformer have different advantages and disadvantages, and the catalyst must be exchanged when each is used alone. Due to such problems as cell shutdown and complication of the cell structure in an internal reforming type reformer, there is a problem that the fuel cell power generator as a whole is not sufficiently reliable in terms of operation efficiency and the like. there were.

[Object of the Invention]

It is an object of the present invention to improve the reforming performance of a fuel cell power generator equipped with a reformer and increase the flexibility of operation.

[Outline of Invention]

The present invention relates to a fuel cell power generator including an external reformer and an internal reformer, draws out gas flowing through the external reformer, separates hydrogen gas in the drawn-out gas, and separates the separated hydrogen gas. It is characterized in that a hydrogen gas separation device for supplying the generated hydrogen gas to the internal reforming device and for returning the gas after separating the hydrogen gas to the external reforming device is provided.

Example of Invention

An embodiment of a fuel cell power generator according to the present invention will be described in detail with reference to the accompanying drawings.

In the following examples, a molten carbonate fuel cell power generator having a molten carbonate as an electrolyte and a cell operating temperature of about 650 ° C. will be described. Also, a case will be described in which methane is used as fuel, steam is used as the reforming device, and a steam reforming device that reforms this methane into hydrogen gas is used. The present invention can be carried out in the same manner as in the following examples even in the case of a raw material other than methane or a reforming method.

First, the configuration of this embodiment will be described.

FIG. 1 is a system diagram showing a configuration of an embodiment of the present invention.

In FIG. 1, a fuel cell power generator 1 comprises an anode 3 and a cathode 4 that sandwich an electrolyte plate 2, an anode chamber 5 that surrounds the anode 3, and a cathode chamber 6 that surrounds the cathode 4. It Inside the anode chamber 5, an internal reforming device 7 is provided, which holds a reforming catalyst for promoting a reforming reaction from methane and steam to a gas rich in hydrogen. For example, Ni can be used as the reforming catalyst.

On the other hand, the external reformer 8 has a reaction tube 9 inside and is provided with pipes 11 and 12 for circulating a catalyst body that heats the reaction tube 9. Anode chamber 5 in reaction tube 9
Similar to the above case, the reforming catalyst 10 for promoting the reforming reaction from methane and steam to a gas rich in hydrogen is held. A pipe 14 for fluidly connecting one end of the reaction tube 9 of the external reformer 8 and one end of the internal reformer 7
Is provided. At the other end of the reaction tube 9 of the external reforming device 8, a pipe 13 for introducing a raw material gas in which methane and steam are mixed is provided. On the other hand, a pipe 15 for flowing out the exhaust gas of the anode 3 is provided at the other end side of the external reforming device 8 in the anode chamber 5 of the fuel cell power generator 1.

The present invention is characterized in that a hydrogen gas separation device 22 which is fluidly connected to the external reforming device 8 is provided. Pipes 23 and 25 for extracting the reaction gas in the reaction tube 9 are provided at an intermediate point in the tube axis direction of the reaction tube 9 of the external reformer 8.
Further, pipes 24 and 26 for returning a part of the extracted gas into the reaction tube are provided. The other ends of the reformers of these pipes 23, 24, 25 and 26 are connected to the hydrogen gas separator 22. The hydrogen gas separation device 22 is provided with a pipe 27 for guiding the hydrogen gas obtained by further separation, and the other end of the pipe 27 has the reaction pipe 9 of the reformer 8 and the fuel cell power generator 1 14 connecting the internal reformer 7 in the anode material 5 of
It is provided so that it will join.

Next, the operation of this embodiment will be described.

The mixed reaction gas of methane and steam that has flowed into the reaction tube 9 of the reformer 8 through the pipe 13 flows through the pipe 11 and is supplied with heat from the heat medium that flows into the reformer 8 while the reaction tube A reforming reaction is caused under the reforming catalyst 10 held in 9 to become a hydrogen-rich gas. A part of the gas containing hydrogen is introduced into the hydrogen gas separation device 22 through a pipe 23 provided at an intermediate point in the axial direction of the reaction tube 9, and separated into hydrogen gas and a gas other than hydrogen gas. It The separated hydrogen gas is sent to the pipe 14 through the pipe 27, and the gas other than the hydrogen gas is returned to the reaction pipe 9 through the pipe 24. Here, the gas composition in the reaction tube 9 shifts the equilibrium of the steam reforming reaction by the amount of the separated and removed hydrogen gas, and the reaction in the direction of further producing hydrogen is promoted. Similarly, a part of the gas in the reaction tube 9 is guided to the hydrogen gas separation device 22 through a pipe 25 provided at another middle point in the tube axis direction of the reaction tube 9 and separated into hydrogen gas and a gas other than hydrogen gas. The separated and separated hydrogen gas is fed into the pipe 14 through the pipe 27, and the gas other than the hydrogen gas is returned into the reaction pipe 9 through the pipe 26. As a result, the steam reforming reaction further progresses, and the production of hydrogen gas is promoted. Thus, the hydrogen-enriched gas obtained as a result of the reforming rate exceeding the equilibrium reaction rate at the operating temperature of the external reformer 8 and separated from unreacted methane flows through the pipe 27, and the reaction tube 9 It is merged with the reformed gas obtained inside and passing through the pipe 14, and is supplied to the internal reformer 7 in the anode chamber. As a result, the reforming reaction proceeds further, and the hydrogenated enriched gas is almost 100% reformed, and this hydrogen enriched gas is used as the anode gas.

The better the separation performance of the hydrogen gas separation device 22, the higher the reforming rate. Further, the external reforming device 8 and the hydrogen gas separation device 22 may be integrally configured, and the number of pipes for extracting the reaction gas is not limited to the number in this embodiment.

According to the present embodiment, since the hydrogen gas separation device connected to the reformer is provided, the reforming rate of the reformer is improved, so that more hydrogen gas can be produced than at the reaction equilibrium. By operating the hydrogen gas separation device, the reforming rate of the reaction and the sharing rate of the reforming reaction between the reforming device and the fuel cell device can be controlled, and the operating range of the fuel cell power generation device can be increased. That is, a flexible fuel cell power generator can be provided. Also, the separated hydrogen can be used for other purposes.

〔The invention's effect〕

As described above, according to the fuel cell power generator of the present invention, by separating the hydrogen from the gas in the external reformer by combining the external reformer and the hydrogen gas separator,
Since the partial pressure of hydrogen decreases, the reforming reaction for producing hydrogen is promoted, and the effect of improving the reforming performance can be obtained.

Further, by operating the hydrogen gas separation device to control the share of each reforming device, the effect of increasing the flexibility of operation can be obtained.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of a fuel cell power generator according to the present invention. 1 ... Fuel cell power generator, 5 ... Anode chamber, 6 ... Cathode chamber, 7,10 ... Reforming catalyst, 8 ... Reforming device, 9 ... Reaction tube, 11, 12, 13, 14, 15, 23, 24, 25, 26, 27 ... Piping, 16 ... Combustor, 22 ... Hydrogen gas separation device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Shiina 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Institute of Mechanical Research, Hiritsu Manufacturing Co., Ltd. (72) Yoshiki Noguchi 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Hitachi, Ltd. In-house (56) Reference JP-A-61-193371 (JP, A)

Claims (2)

[Claims] 1. A battery stack is constructed by stacking a plurality of unit cells each comprising an anode and a cathode, which are arranged opposite to each other with an electrolyte plate sandwiched therebetween, with a separator interposed therebetween, and a gas flow path for the anode and the separator. A fuel cell for supplying hydrogen gas, which is a fuel, to an anode chamber formed by the groove, and supplying an oxidant gas, which is a fuel, to the cathode chamber, which is formed by the gas passage groove of the cathode and the separator, to generate electricity. An external reforming device that holds a reforming catalyst and circulates a fuel containing a hydrocarbon through the reforming catalyst to reform the fuel into a hydrogen-rich gas by a reforming reaction; An internal reformer that is provided and holds a reforming catalyst, circulates the hydrogen-enriched gas through the reforming catalyst, and reforms unreformed fuel contained in the hydrogen-enriched gas into hydrogen gas by a reforming reaction. With quality device In the fuel cell power generation device according to, a gas flowing in the external reforming device is drawn, hydrogen gas in the drawn gas is separated, and the separated hydrogen gas is supplied to the internal reforming device, A fuel cell power generator comprising a hydrogen gas separation device for returning the gas after separation of the hydrogen gas to the external reforming device. 2. A gas flowing in the external reforming apparatus is supplied to the hydrogen gas separating apparatus from a position downstream from a position where the gas after separating the hydrogen gas from the hydrogen gas separating apparatus to the external reforming apparatus is returned. A means for returning the gas after the hydrogen gas is separated from the gas supplied by the gas supply means by the hydrogen gas separation device to the external reforming device. A fuel cell power generator according to item.