JP3021082B2 - Fuel cell system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fuel cell system using a hydrogen separation type reformer and a solid polymer electrolyte type fuel cell.

[0002]

2. Description of the Related Art Conventionally, practical use of a fuel cell system using a hydrogen separation type reformer and a solid polymer electrolyte type fuel cell has been studied. Here, the hydrogen separation type reformer mainly decomposes a raw material gas composed of a hydrocarbon such as methane or methanol or an oxygen-containing hydrocarbon into hydrogen and carbon dioxide by a steam reforming reaction and a CO shift reaction, and is generated thereby. It has an action of selectively separating hydrogen through a hydrogen separation membrane built in the reformer. The hydrogen separation in the reformer is generally performed by flowing an inert gas to the permeation side of the hydrogen separation membrane or reducing the pressure on the permeation side. A solid polymer electrolyte fuel cell generates power by supplying hydrogen gas generated by a hydrogen separation type reformer to a hydrogen electrode and supplying air or oxygen to an air electrode. Since the performance becomes very poor when the gas becomes dry, it is necessary to humidify the hydrogen gas supplied to the hydrogen electrode.

[0003] Such a fuel cell system will be described in more detail with reference to FIG.

In FIG. 5, reference numeral 1 denotes a hydrogen separation type reformer (hereinafter, referred to as a reformer) having a combustion section 2 and a reforming catalyst layer 3 surrounded by the combustion section 2. Further, inside the reforming catalyst layer 3, there is formed a permeation portion 5 which comes into contact with the reforming catalyst layer 3 via a hydrogen separation membrane 4 made of a palladium alloy or the like.

[0005] In the figure, reference numeral 6 denotes a solid polymer electrolyte fuel cell (hereinafter, referred to as a fuel cell), which has a hydrogen electrode 7 and an air electrode 8, and further includes a fuel cell cooling system 9.

[0006] Into the improved catalyst layer 3 of the reformer 1, a mixed gas 12 in which a raw material gas 10 made of a hydrocarbon such as methane and steam 11 are mixed, is introduced.
This mixed gas 12 is decomposed into hydrogen, carbon monoxide and carbon dioxide by respective reactions shown in the following “Chemical formula 1”.

[0007]

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[0008] Of the decomposition gas obtained by the reaction in the reforming catalyst layer 3, only hydrogen is separated into the permeation section 5 through the hydrogen separation membrane 4.

An inert gas 13 is introduced from one of a pair of entrances and exits of the transmission section 5 of the reformer 1, and the transmission section 5
The separated hydrogen gas is discharged from the other of the entrance and exit of the permeation section 5 by an inert gas, and is sent as hydrogen gas 14 to the hydrogen electrode 7 of the fuel cell 6.

On the other hand, a part of the raw material gas 15 and the air 16 are introduced into the combustion part 2 of the reformer 1, and the reforming catalyst layer 3 is heated to an appropriate temperature by the combustion of the raw material gas 15. . The residual gas 17 discharged from the reforming catalyst layer 3 is introduced into the combustion section 2 together with the raw material gas 15 and the like.
8 is discharged.

A heat exchanger 19 and a humidifier 20 are sequentially provided in a system for introducing the hydrogen gas 14 discharged from the reforming catalyst section 3 of the reformer 1 to the hydrogen electrode 7 of the fuel cell 6. After being cooled by the heat exchanger 19, the hydrogen gas 14 is introduced into the humidifier 20. Here, the humidifier 20 includes a humidifier heating system 21, and has an operation of evaporating water 22 separately introduced and humidifying the hydrogen gas 14. That is, the hydrogen gas 14 is humidified by the humidifier 20 and introduced into the hydrogen electrode 7 as the humidified hydrogen gas 23.

On the other hand, the air 24 is supplied to the air electrode 8 of the fuel cell 6.
Has been introduced. Then, in the fuel cell 6, electricity is generated by the reaction between the humidified hydrogen gas 23 and the air 24. The unreacted hydrogen gas 25 discharged from the hydrogen electrode 6
Is the transmission part 15 of the reformer 1 through the circulation blower 26.
Mixed with the inert gas 13 sent to the
Is discharged as air electrode exhaust gas 27.

[0013]

In the above-described fuel cell system, when the solid electrolyte of the solid polymer electrolyte fuel cell 6 is in a dry state, the performance generally deteriorates greatly. Humidifier 20
Is always required. In the hydrogen separation type reformer 1, a decompression pump or an inert gas 13 is used for hydrogen separation.
It is necessary to provide a circulation pump for circulating water. In addition, these pumps need to be high in safety and reliability in order to handle hydrogen, which causes high equipment costs.

The present invention has been made in view of such circumstances, and has as its object to provide a fuel cell system that improves humidification and hydrogen separation of hydrogen gas.

[0015]

A fuel cell system according to the present invention, which achieves the above object, uses a hydrocarbon as a raw material,
Separation reformer for selective separation of hydrogen and solid fractionation
Fuel cell system having a solid oxide fuel cell
Supply water or steam to the ejector
Water separated by the reformer due to the suction force generated
Hydrogen and remove the absorbed hydrogen from the water or steam.
It is supplied to the hydrogen electrode of the fuel cell together with the system
And In the above invention, the fuel cell has not
Reacting hydrogen gas is circulated to hydrogen separation type reformer
It may be. In the above invention, the hydrogen electrode of the fuel cell
Circulate the unreacted hydrogen gas to the ejector
You may. In the above invention, an ejector action is caused.
The rubbing drive fluid may be steam. In the above invention
And the driving fluid that causes the ejector action is water.
You may.

[0016]

In the fuel cell system having the above structure, in the hydrogen separation type reformer, the suction force generated by the ejector action is used to separate the hydrogen, so that a pressure reducing pump or a circulation pump for circulating the inert gas is used. It eliminates the need for this and increases safety when handling hydrogen gas. Further, when steam or water is used as the driving fluid that causes the ejector action, the action of humidifying the hydrogen separated from the hydrogen separation type reformer can be obtained at the same time, so that it is not necessary to use a humidifier.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
In the drawings showing the respective embodiments, members having the same functions as those in FIG. 5 are denoted by the same reference numerals, and overlapping description will be omitted.

FIG. 1 conceptually shows a fuel cell system according to a first embodiment. As shown in the figure, in the present embodiment, an ejector 31 is used for separating hydrogen in the reformer 1 and for humidifying the separated hydrogen.

Steam 32 is introduced into the ejector 31 as a driving fluid, and the suction side of the ejector 31 is connected to one of a pair of entrances and exits of the transmission section 5 of the reformer 1. The other of the entrance and exit of the transmission section 5 has a fuel cell 6
The unreacted hydrogen gas 25 from the hydrogen electrode 7 is introduced, but a blower for sending the unreacted hydrogen gas 25 is not particularly provided.

The suction action (pump action) of the ejector 31
The hydrogen gas 14 discharged from the permeation section 5 is humidified by the steam 32 in the ejector 31 and introduced into the heat exchanger 19, and is set to almost the operating temperature of the fuel cell 6.
The water is sent to the water separator 33. In the water separator 33, the condensed water 34
Is separated, and the humidified hydrogen gas 23 is introduced into the hydrogen electrode 7.

In the fuel cell system of the present embodiment, the separated hydrogen is discharged from the hydrogen separation type reformer 1 by the suction action (pump action) of the ejector 31 using the steam 32 as a driving fluid, and the hydrogen can be humidified. Is not required, and a pump or the like for circulating an inert gas for discharging hydrogen gas is not required. Therefore, the cost of the apparatus can be reduced, and a mechanism that cannot be electrically driven can be employed in a portion that is in direct contact with hydrogen, thereby improving safety.

FIG. 2 conceptually shows a fuel cell system according to a second embodiment. As shown in the drawing, this embodiment uses an ejector 31 using steam 32 as a driving fluid, as in the first embodiment, but transmits unreacted hydrogen gas 25 from the hydrogen electrode 7 through the reformer 1. Instead of being sent to the section 5, it is introduced to the suction side of the ejector 31. That is, the entrance of the transmission part 5 of the reformer 1 is made into one place,
The suction side of the ejector 31 is connected to this entrance.

In this embodiment, the inside of the permeation section 5 is depressurized by the suction action of the ejector 31, whereby hydrogen is separated. The other operation and effects are the same as those of the first embodiment in FIG. is there.

FIG. 3 conceptually shows a fuel cell system according to a third embodiment. As shown in the figure, in this embodiment, an ejector (jet pump) 41 using water as a driving fluid is used, and water 42 is sent to the ejector 41 as a driving fluid by a water pump 43. Here, unreacted hydrogen gas from the hydrogen electrode 7 of the fuel cell 6 is sent to one of a pair of ports of the permeation section 5 of the reformer 1, and the suction side of the ejector 41 is connected to the other of the ports of the permeation section 5. I have. The heat exchanger 19 is interposed between the permeation section 5 and the ejector 41, and a water separator 33 is provided downstream of the ejector 41.

Therefore, in this embodiment, the ejector 4
The hydrogen gas 14 discharged from the permeation part 5 by the suction action (pump action) of 1 is cooled by the heat exchanger 19,
The water is mixed with the water in the form of spray by the ejector 41, humidified and sent to the water separator 33. Then, excess water is removed in the water separator 33, and the humidified hydrogen gas 23 is sent to the hydrogen electrode. The condensed water 34 removed by the water separator 33 is sent to the upstream side of the water pump 43.

The fuel cell system according to the present embodiment includes an ejector 41 using water 42 sent from a water pump 43 as a driving fluid.
Of the hydrogen separation type reformer 1 can be discharged and the hydrogen can be humidified by the suction action (pump action) of the present invention, and the same operation and effect as those of the above-described embodiment can be obtained.

FIG. 4 conceptually shows a fuel cell system according to a fourth embodiment. As shown in the drawing, this embodiment uses an ejector 41 using water 42 as a driving fluid, as in the third embodiment shown in FIG. 3, but removes unreacted hydrogen gas 25 from the hydrogen electrode 7. Instead of being sent to the transmission section 5 of the reformer 1, it is introduced to the suction side of the ejector 41.
That is, the entrance of the transmission part 5 of the reformer 1 is made into one place, and the suction side of the ejector 41 is connected to this entrance.

In this embodiment, the inside of the permeation section 5 is decompressed by the suction action (pump action) of the ejector 41, whereby hydrogen is separated. The other action and effect are shown in FIG. This is the same as the embodiment.

Here, in each embodiment, the reformer 1
Tables 1 to 4 show an example of conditions of the hydrogen gas 14 separated in the above and the humidified hydrogen gas 23 sent to the hydrogen electrode 7 of the fuel cell 1.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

As described above, since the fuel cell system of the present invention uses the suction force generated by the ejector action, an expensive motor-driven pressure reducing pump or circulation pump is unnecessary, and the hydrogen gas Safety when handling is increased. In addition, by using steam or water as the driving fluid for obtaining the ejector action, the hydrogen gas can also be humidified, so that there is no need to provide a humidifier.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a fuel cell system according to a first embodiment.

FIG. 2 is a conceptual diagram of a fuel cell system according to a second embodiment.

FIG. 3 is a conceptual diagram of a fuel cell system according to a third embodiment.

FIG. 4 is a conceptual diagram of a fuel cell system according to a fourth embodiment.

FIG. 5 is a conceptual diagram of a fuel cell system according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydrogen separation type reformer 2 Burning part 3 Reforming catalyst layer 4 Hydrogen separation membrane 5 Permeation part 6 Solid polymer electrolyte fuel cell 7 Hydrogen electrode 8 Air electrode 14 Hydrogen gas 19 Heat exchanger 23 Humidified hydrogen gas 31, 41 Ejector 32 Steam 33 water separator 42 water

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takafumi Shimada 4-6-22 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute (56) References JP-A-2-311301 (JP, A) JP-A-6-168733 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 8/00-8/24 C01B 3/32

Claims (5)

(57) [Claims] 1. A method for selectively separating hydrogen from a hydrocarbon as a raw material.
Separating hydrogen reformer and solid polymer electrolyte fuel
In a fuel cell system with a battery, the fuel is supplied by supplying water or steam to the ejector.
Hydrogen separated by the above reformer due to the generated suction force
Withdrawing the absorbed hydrogen with the water or steam.
A fuel cell system , wherein both are supplied to a hydrogen electrode of the fuel cell. 2. The hydrogen separation type fuel cell according to claim 1, wherein unreacted hydrogen gas from the hydrogen electrode of the fuel cell is removed.
Fuel cell system characterized by being circulated to the former
M 3. An ejector according to claim 1, wherein unreacted hydrogen gas from a hydrogen electrode of the fuel cell is supplied to an ejector.
A fuel cell system characterized by being circulated. 4. The fuel cell system according to claim 1, wherein the driving fluid causing the ejector action is steam. 5. The fuel cell system according to claim 1, wherein the driving fluid causing the ejector action is water.