JPH03109202A - Fuel reformer for fuel cell system - Google Patents

Abstract

PURPOSE:To miniaturize the reformer by effectively combining catalytic reforming and a heated reaction utilizing a honeycomb porous body. CONSTITUTION:The fuel reformer 76 is provided with a honeycomb porous body. The porous body consists of the first passage 10 consisting of many independent through holes enclosed by a partition wall 15, the second passage 17 divided and formed by a connecting wall 16 for connecting the adjacent partition walls and isolated from the first passage 10, a reforming catalyst deposited on the inner wall of the first passage 10 or the second passage 17 and used for reforming a gaseous fuel into a reformed gas and a catalytic combustion catalyst deposited on the inner wall of the first passage 10 or the second passage 17 and used for burning a catalytic combustion gas.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel reformer for a fuel cell system, and particularly to a heater for a fuel reformer.

(Conventional technology) While thermal power generation, nuclear power generation, etc. obtain electrical energy by converting the chemical energy of fossil fuels into thermal energy or nuclear energy, fuel cells obtain electrical energy directly from chemical energy. This fuel cell is a chemical cell in which reactants are continuously supplied from the outside, and the main components are a fuel cell main body, a fuel reformer, and a power converter, and these components include a control device, A fuel cell system is configured with the addition of an exhaust heat recovery device, etc.

Among these, the fuel reformer is a device that reforms fossil fuel gas as a raw material gas into hydrogen-rich reformed gas. It consists of a CO transformer that reduces carbon monoxide in quality gas to below the permissible concentration.

For example, as shown in FIG. 8, the fuel gas flowing into the fuel gas chamber 41 from the fuel gas population 50 enters the reaction tube 42 from the direction of the arrow, and is reformed by the pellet catalyst 43 filled in the reaction tube 42. After the reaction occurs, the reacted reformed gas enters the flow pipe 44, flows in the direction of arrow B in the figure, and is supplied from the fuel gas outlet 46 to the CO shift converter. At this time, the heating chamber 53 is heated by the flame generated by the burner 52, the reforming reaction within the reaction tube 42 is promoted, and the fuel gas is converted into a reformed gas containing hydrogen, carbon dioxide, and carbon monoxide. Ru.

(Problems to be Solved by the Invention) However, in the conventional fuel reformer of the fuel cell system, the catalyst used for the reforming reaction is a pellet catalyst, so the contact area with the fuel gas is small and uniform heating is not possible. This method is difficult, has a large pressure loss, and has problems in that the reaction tube is likely to become clogged due to the generation of soot caused by the reduction reaction.

The present invention was made to solve these problems, and uses a honeycomb-like block (porous body) having a specific structure and a first passage and a second passage having a large contact area. By supporting a catalyst for catalytic combustion in one of the first passage or the second passage and supporting a reforming catalyst in the other passage, the reforming catalyst can be heated using catalytic combustion. An object of the present invention is to provide a reformer for a fuel cell system that can be downsized and promotes the reforming reaction of fuel gas into reformed gas.

(Means for Solving the Problems) A fuel reformer for a fuel cell system according to a first aspect of the present invention includes a first passageway consisting of a large number of independent through holes surrounded by a partition wall, a second passage separated from the passage via a partition wall and defined by a connecting wall that connects adjacent partition walls; , a reforming catalyst that converts fuel gas into reformed gas; and a catalytic combustion catalyst that is supported on the inner wall of the other of the first passage or the second passage and catalytically burns the catalytic combustion gas. It is characterized by having a honeycomb-like porous body consisting of.

A fuel reformer for a fuel cell system according to a second aspect of the present invention, in addition to the fuel reformer according to the first aspect, generates heat from the reformed gas flowing out from the passage in which the reforming catalyst is supported. a first heat exchanger that provides heat to the fuel gas flowing into the passage; a catalytic combustion gas supply source that supplies gas for catalytic combustion to catalytically combust the fuel gas with the catalytic combustion catalyst; A second heat exchanger that removes heat from the catalytic combustion exhaust gas discharged from the passageway in which the catalyst is supported and gives heat to the fuel gas flowing into the passageway in which the reforming catalyst is supported. Features.

(Function) According to the fuel reformer of the present invention, since the honeycomb-like porous body having the above-described specific structure is used, all of the partition walls surrounding the through holes of this porous body are used for contact such as heat transfer and mass transfer. The area of contact between the first passage and the second passage through which different fluids, catalytic combustion gas and fuel gas, flow independently is increased by using the catalytic combustion catalyst for heating and reforming. The reforming reaction by the catalyst is simultaneously promoted in the honeycomb structure with low pressure loss, and the efficiency of the reforming reaction can be dramatically improved even with a small reformer.

(Example) Embodiments of the present invention will be described below based on the drawings.

First, a phosphoric acid fuel cell system using the fuel reformer of the present invention will be explained.

As shown in FIG. 9, the phosphoric acid fuel cell system includes a fuel cell main body 61, a fuel reformer 62, and a current converter 63.
, an exhaust heat recovery device 64 is the main component.

In the fuel cell main body 61, an anode 65 and a cathode 66 are brought into contact with an electrolyte solution consisting of an aqueous phosphoric acid solution.
Hydrogen in the hydrogen-rich gas led to the 5 side and the cathode 66
Electricity is generated by electrochemically reacting oxygen in the air introduced to the side using, for example, platinum as a catalyst.

The fuel reformer 62 is a device for reforming fossil fuel gas into hydrogen-rich gas, and includes a desulfurizer 75 that removes sulfur compounds from the fossil fuel gas, and converts the desulfurization raw material gas into hydrogen, carbon dioxide, and carbon monoxide. and a CO converter 77 that reduces carbon oxide to a permissible concentration or less. C.O.
The reformed gas reformed by the converter 77 is sent to the anode 65 of the fuel cell main body 61 as hydrogen-rich gas. In addition,
The current converter 63 converts the direct current generated by the fuel cell main body 61 into a practical alternating current.

The fuel reformer 76 of the phosphoric acid fuel cell system configured as described above has a reformer body (porous body) 30 as shown in FIGS. 1, 2, and 3. The fuel reformer 76 is formed into a rectangular parallelepiped shape by stacking a large number of reformer bodies 3o as shown in FIG. The second passage is separated from the first passage and communicates from the direction of arrows C and E in the direction of arrows C and F in the illustration. In this case, the catalytic combustion gas (mixture) enters the first passage from the direction of the six arrows shown, the combustion exhaust gas is discharged to the outside from the direction of the arrow B, and the fuel gas enters from the direction of the arrow C or E. The reformed gas after the reforming reaction is discharged through the second passage in the direction of the arrow or F in the figure.

The mixture used for catalytic combustion gas is LNG, LPG
A flow rate control device 33.3 controls hydrocarbon fuel such as
The mixture is used after being mixed to a predetermined air-fuel ratio using the mixer 35 whose flow rate is adjusted by 4. A catalyst for catalytic combustion is supported on the inner wall surface of the first passage of the reformer main body 30 into which such an air-fuel mixture is introduced. As a catalyst for catalytic combustion, platinum,
Using at least one of palladium, rhodium, cobalt, etc., γ-
It is preferable to support A2□Q3, Zr0i, etc. and then attach these catalysts for catalytic combustion.

The specific structure of this reformer main body 30 is, for example, a honeycomb-shaped porous body shown in FIGS. 4 and 5. Figure 4,
As shown in FIG. 5, a first passage consisting of a large number of independent through holes 10 penetrates from the end surface X to the end surface X° of the porous body, and the through holes 10 (first The portion 11 is integrally and airtightly connected and sealed with the outer wall 12.There is an opening 13 that opens to the outside of the outer wall 12 in the Y plane, which is different from the end faces x and x'. another opening 13' on the Y'' plane, opening 1<' on the Z' plane.
4 are provided respectively.

Then, the catalytic combustion gas is caused to flow into the openings of the many through holes 10 in the end surface X in the direction of arrow A, catalytic combustion is performed, and the combustion exhaust gas is caused to flow out in the direction of arrow B. On the other hand, the fuel gas (low-temperature heat exchange A target fluid) is flowed to exchange heat with the catalytic combustion gas (high temperature heat transfer medium). Next, FIG. 6 shows a cross section taken along line MM' of the porous body shown in FIG. 4.

That is, as shown in FIG. 6, a large number of independent through holes 10 opening in the end surface X in FIG. 4 are each an independent through hole surrounded by a partition wall 15. The partition wall 15 that divides the independent through hole 10 is connected to the partition wall 15 of the adjacent independent through hole 10, and similarly, the partition wall 15 is connected to the outer wall 12 by a connecting wall 16. As a result, a partition wall 15 and an outer wall 1 are formed around each through hole IO.
2 and the connecting wall 16 form a continuous second passage 17, and the second passage 17 communicates with the opening 13.13° and the opening 14.14° and opens to the outside of the outer wall 12. It has become.

Therefore, as shown in FIG.
The honeycomb structure is in contact with the second passage 17, which is different from the through hole IO, on all sides in the direction of side a%b%C%d, and has a normal heat transfer area and contact area when used as a heat exchanger. It is a porous body that is considerably larger than that of the porous body, which greatly improves heat exchange efficiency, catalytic reaction efficiency, etc.

In addition, in this porous body, each through hole 10 exists independently, and the partition wall 15 that divides each through hole 10 is also independent, and does not share a partition wall with the partition wall 15 of an adjacent through hole 10. Since the independent partition walls 15 are connected by the connecting wall 16, deformation due to thermal stress can be adjusted.
It has a thermally flexible structure.

Note that in the porous body shown in FIG. 4, the connecting walls 16 connecting the partition walls 15 are connected at symmetrical positions with respect to the through holes 10 as shown in FIGS. 6 to 7, but they are not necessarily symmetrical. There is no need to be. In addition, in FIGS. 4 and 5, the continuous second passage 17 surrounding the first passage consisting of each through hole 10 is provided at four locations with an angle of 13.13° and 14.14°. Of course, the passage 17 may have only the openings 13 and 14.

As the material for forming this porous body, any dense material can be selected, and specifically, materials such as metal, ceramic, glass, etc., or composite materials thereof are preferable.

Among them, inorganic materials or metal materials such as refractories, ceramics, glass, carbon materials, etc. are preferable, and these inorganic materials include, for example, carbon, mullite, cordierite, silica, zircon, silica-alumina, sillimanite, zirconia, zircon mullite, and spinel. , zirconia-spinel, titania, alumina, clay, beryllia, alumina-titanate, mullite-alumina titanate, magnesia-alumina titanate, zeolite, Vycor glass, silicon carbide, silicon nitride, LaCo0, La-5r-C
oos, 5r-Ce-Y-0,5r-Ce-Zn-
0, BaTi0z, GaAs% Zr0-Ca0%
ZnO5S n Oi , Fe * Os
s5rTioz, PbO-Zr0i-Ti
Oa, LiTags, LaCr0z, Ga
P% CBN% Zr0% ZrO* -Y* O
3. TaC, GaAsP.

Materials such as L a B a and combinations thereof, and metal materials such as aluminum, copper, and iron are preferable materials because the porous body can be manufactured integrally by extrusion molding relatively easily.

Further, the cross-sectional shape of the through-holes of this porous body may be any shape, but circles, ellipses, triangles, quadrangles, pentagons, hexagons, etc. are particularly preferred.

A surface layer of a reforming catalyst containing nickel as a main component is formed on the inner wall of the second passage mentioned above. The components of the reforming catalyst are not limited to nickel.

Such a fuel reformer 76 discharges reformed gas from the passage 21 as shown in FIG. The reformed gas from which heat has been removed is sent to the CO shift converter 77. On the other hand, the fuel gas that has taken the heat of the reformed gas in the first heat exchanger 22 is
It flows into the second heat exchanger 23 via the passage 20. Then, the fuel gas absorbs heat from the fuel exhaust gas discharged from the first passage of the reformer body 30, and is sent to the reformer body 30 through the passage 24 in a heated state. On the other hand, the second heat exchanger 23
The fuel exhaust gas from which heat has been removed is discharged to the outside from the passage 25.

When the heated fuel gas flows from the passage 24 into the reformer main body 30 in the directions of arrows C and E shown in FIG. 2 or 3, a reforming reaction by the reforming catalyst occurs in the second passage. The reformed gas is converted into reformed gas, flows out from the direction of the arrow and F, and is sent from the passage 21 to the next CO shift converter 77 via the first heat exchanger 22.

On the other hand, the catalytic combustion gas flowing in the direction from arrow A to arrow B through the first passage formed by the through hole 10 of the reformer main body 30 is supplied from the air-fuel mixture 35 as a fuel supply source. This catalytic combustion gas is supplied because the reforming reaction occurring in the reformer main body 30 is an endothermic reaction and requires a large amount of heat.

In this example, the heat transfer rate is higher than that of a normal honeycomb structure.
Since a porous body having the above-mentioned special structure with a wide contact area for mass transfer is used, heat exchange efficiency, reaction efficiency, etc. are dramatically increased, and the reforming reaction is promoted. Thereby, it is possible to downsize the fuel reformer 76 while maintaining the same thermal efficiency and reaction efficiency. Therefore, even in a small fuel reformer, the reforming ability of the reforming catalyst is extremely high due to the heating effect of the catalytic combustion catalyst. In this embodiment, the fuel gas is heated in advance using the first heat exchanger 22 and the second heat exchanger 23 and then flows into the reformer 3o, and the heat of the exothermic reaction is efficiently transferred. Used to raise the temperature of fuel gas,
This has the effect of promoting the reforming reaction.

(Effects of the Invention) As explained above, according to the fuel reformer of the fuel cell system of the present invention, the heat of the reformed gas generated by the reforming reaction can be efficiently used to raise the temperature of the fuel gas, and The fuel gas, which has been heated by the heat of the combustion gas from catalytic combustion in the reformer made of a honeycomb structure porous body, is efficiently subjected to a reforming catalytic reaction in the porous body with a large contact area. can be efficiently converted into reformed gas (
This has the effect that the capacity of the reformer can be made smaller. Moreover, compared to burner heating, the reforming catalyst is heated to the same temperature and quickly. Moreover, since the pressure loss is low, there is an effect that the blower can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the stacked state of the reformers of a fuel reformer according to a first embodiment of the present invention, FIG. 2 is a schematic perspective view showing the fuel reformer, and FIG. 3 is a schematic perspective view of the fuel reformer. System diagrams showing the fuel gas flow path of the fuel reformer, Figures 4 and 5
The figure is an explanatory diagram showing the external appearance of a specific example of a porous body in an embodiment of the present invention, FIG. 6 is an explanatory diagram showing a cross section taken along line M-M' in FIG. 4, and FIG. 7 is a partially enlarged cross section of FIG. 6. 8 is a schematic configuration diagram showing a conventional fuel reformer, and FIG. 9 is a circuit diagram showing a circuit configuration of a phosphoric acid fuel cell system to which the present invention is applied. a! , insertion fork 0 2 13, 5 6 7 2 3 0 6 ... through hole (first passage), ... outer wall, 14 ... opening, ... partition wall, ... connecting wall, ...second passage, ...first heat exchanger, ...second heat exchanger, ...reformer main body, ...fuel reformer.

Claims (1)

[Claims] (1) A first passage consisting of a large number of independent through holes surrounded by a partition wall, and a first passage separated from the first passage via a partition wall and divided by a connecting wall connecting adjacent partition walls. a reforming catalyst that is supported on the inner wall of one of the first passage or the second passage and converts the fuel gas into reformed gas; A fuel reforming device for a fuel cell system, comprising: a catalytic combustion catalyst supported on the inner wall of the other of the passages to catalytically combust catalytic combustion gas; and a honeycomb-shaped porous body. (2) a first heat exchanger that removes heat from the reformed gas flowing out from the passage in which the reforming catalyst is supported and gives heat to the fuel gas flowing into the passage; and the catalytic combustion catalyst. A catalytic combustion gas supply source that supplies catalytic combustion gas to be catalytically combusted; and a catalytic combustion gas supply source that supplies heat from the catalytic combustion exhaust gas discharged from the passage in which the catalyst for catalytic combustion is carried, and the passage in which the catalyst for reforming is carried. The fuel reformer for a fuel cell system according to claim 1, further comprising: a second heat exchanger that provides heat to the inflowing fuel gas.