JPH0867502A - Fuel reformer - Google Patents

Abstract

PURPOSE: To provide a fuel reformer having small volume of a catalytic layer and small catalytic amount, capable of attaining cost down and carrying out reforming reaction in high efficiency and miniaturizing. CONSTITUTION: A gas which flows into a reacting tube 1 is discharged from the outlet of the first catalyst part 12 before lowering to a carbon deposition temperature Tc in the first catalyst part 12 and the gas is heated by a heating furnace 2 in a heat transfer promoting part 5 on the downstream side of the first catalyst part to raise the temperature of the gas. Then, the gas is fed into the second catalyst part 13 and reforming reaction of the gas by the second catalyst part 13 is promoted and the gas is discharged before the temperature of the gas is lowered to a temperature lower than a carbon deposition temperature Tc also in the second catalyst part 13. Since the gas alternately flows into catalytic parts 12, 13, 14, 15 and 16 and heat transfer promoting parts 5, 6, 7 and 8, reaction temperature is always retained to a temperature exceeding the carbon deposition temperature Tc. As a result, deposition of carbon is suppressed and operation having low S/C value is made possible and efficiency of a fuel cell system can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel reformer, and more particularly to a structure of a catalyst layer portion provided in a fuel reformer such as a fuel cell system or a hydrogen generator.

[0002]

2. Description of the Related Art In thermal power generation, nuclear power generation, etc., electric energy is obtained after converting chemical energy of fossil fuel into heat energy or nuclear energy, whereas a fuel cell directly obtains electric energy from chemical energy. This fuel cell is a chemical cell in which reactants are continuously supplied from the outside, and a fuel cell main body, a fuel reformer, and a power converter are main constituent elements, and a control device is added to these constituent elements. A fuel cell system is constructed by adding an exhaust heat recovery device.

Of these, the fuel reforming apparatus is an apparatus for reforming a raw material gas containing a fuel gas such as methane and steam as main components into a hydrogen-rich reformed gas. The raw material gas is mixed with hydrogen and carbon dioxide gas. It is composed of a reformer for converting carbon oxides and a CO shifter for converting carbon monoxide in the reformed gas to an allowable concentration or less. Known catalysts for the reformer include pellet catalysts and honeycomb catalysts.

In the reformer, when the raw material gas passes through the catalyst layer filled in the reaction tube, the raw material gas is reformed and CO
Supplied to the transformer. At this time, since it is the steam reforming method, the reforming reaction in the reaction tube is promoted by being heated by the heater, and the raw material gas is converted into the reformed gas containing hydrogen, carbon dioxide gas and carbon monoxide. . (Reforming reaction) CH ₄ + H ₂ O → 3H ₂ + CO − Endothermic reaction (shift reaction) CO + H ₂ O → CO ₂ + H ₂ − Exothermic reaction

[0005]

However, since the above-mentioned reforming reaction is an endothermic reaction, in the conventional fuel reforming apparatus, a large temperature drop occurs in the catalyst during the progress of the reaction, and the reactivity also decreases accordingly. The reforming reaction proceeds at a temperature of 500 ° C. or higher. At this time, in order to prevent the precipitation of carbon C during the reforming reaction, H ₂ O / CH _{4 of the} reaction gas is used.
Value (this ratio is called S / C value) is set to a value of 3 to 4, for example. The theoretical ratio of S / C value of the reforming reaction is 1 (S / C =
1).

However, increasing the S / C value generally lowers the system efficiency of the fuel cell. this is,
This is because the amount of heat required to heat the excess steam increases.
Generally, in the reaction tube, as shown in FIG. 10, a heating furnace 2 is installed on the outer peripheral portion of the reaction tube 1, a catalyst part 3 is provided inside the reaction tube 1, and a fuel gas such as methane is supplied from the upstream side. When steam is caused to flow in the direction of the arrow, at that time, the temperature of the catalyst portion 3 decreases due to the heat absorption of the reforming reaction from the inlet side of the catalyst portion toward the downstream side. When this temperature is lowered, carbon is likely to be deposited. In order to make this carbon precipitation reaction less likely to occur, the amount of water vapor is made relatively large.

Next, a honeycomb support for supporting the catalyst on the catalyst portion
Temperature of the central part of the honeycomb and the outside of the honeycomb when using a holder
The temperature distribution of the peripheral portion is shown in FIG. The experimental conditions here are the reaction
Tube outer wall temperature: 900 ° C., gas flow rate SV = 5000 hr ^-1
And The reaction conversion rate was 90%. From this figure 9
As in the case of honeycomb-shaped catalyst,
The heat transfer effect of the heating furnace to the
Since the heat conductivity of the
It is very large, the heat supply is insufficient in the center,
Temperature required for reaction at the center of the catalyst depending on the amount of gas supplied
There is a problem that can not be reached.

An object of the present invention is to provide a fuel reformer capable of reducing the S / C value in order to improve the system efficiency of the fuel cell. Another object of the present invention is to provide a fuel reformer capable of operating at a low S / C value. Still another object of the present invention is to provide a fuel reformer capable of downsizing, which has a small catalyst layer volume, a small amount of catalyst, can reduce costs, and can efficiently perform a reforming reaction.

[0009]

In the fuel reforming apparatus of the present invention, in claim 1, a reaction tube for flowing a raw material gas, a first catalyst section arranged in the reaction tube, and a first catalyst section are provided. A second catalyst part spaced apart from the catalyst part;
And a heat transfer promoting section for applying heat from the outside between the catalyst section and the second catalyst section, and the temperatures in the first catalyst section and the second catalyst section are maintained at temperatures at which carbon deposition is avoided. The axial length of the catalyst portion is set so that

The catalyst portion may be a catalyst supported on a honeycomb structure or a pellet catalyst. When a honeycomb catalyst is used, the reaction area is improved because the contact area between the gas and the catalyst is relatively large. It is desirable that the catalyst portion is a thin layer within a predetermined length in the flow direction.
The catalyst layer is formed in a donut shape or a ring shape. In this case, heat can be received from both the radially outer side and the radially inner side of the catalyst layer. The doughnut-shaped catalyst layer can be unidirectionally gas-circulated, or the gas can be passed through the donut-shaped catalyst layer portion and then the gas can be passed through the inner hole portion of the donut-shaped catalyst layer.

A plurality of the second catalyst portions can be provided. That is, by alternately providing the catalyst section and the heat transfer promoting section, it is possible to relatively shorten the axial length of the reaction tube and improve the reaction conversion rate. A heat transfer promoting section is provided between adjacent catalyst sections, and a heat transfer promoting body is provided upstream of the heat transfer promoting section. In this case, the temperature of the gas discharged from the catalyst section outlet on the upstream side of the heat transfer promotion section can be quickly raised.

The heater is set so that the outlet side of each catalyst portion receives a relatively larger amount of heat than the inlet side. This is because the gas temperature can be effectively increased because the gas temperature is relatively lower near the outlet than at the catalyst portion inlet. A heat transfer heater, a burner, or the like can be used as the heater.

[0013]

According to the fuel reforming apparatus of the present invention, the gas flowing into the reaction tube is discharged from the outlet of the first catalyst portion before the temperature falls below the carbon deposition temperature Tc in the first catalyst portion, The downstream portion of the first catalyst portion receives heat from the heater to increase the temperature, then enters the second catalyst portion, and the reforming reaction by the second catalyst portion is promoted, and also in the second catalyst portion. The gas is discharged from the outlet of the second catalyst portion before the temperature falls below the carbon deposition temperature Tc, and by alternately flowing through such a catalyst portion and the heat transfer promoting portion,
The reaction temperature is always kept above the carbon deposition temperature. For this reason, carbon deposition is suppressed and operation with a low S / C value becomes possible, so that the efficiency of the fuel cell system can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. The basic principle of the present invention will be described with reference to FIG. The fuel reforming device 10 mainly reforms the fuel gas and steam in the raw material gas. This fuel reformer 10
Inside the reaction tube 1 constituting the
3, 14, 15, 16 are arranged at intervals, and the catalyst parts 12, 13, 1 adjacent to the heat transfer promoting parts 5, 6, 7, 8 are provided.
Heat is transmitted to the heaters 4, 15 and 16 from the surrounding heater 2. The heater 2 is arranged so as to wrap the entire outer wall surface of the reaction tube 1.

The catalyst parts 12, 13, 14, 15, 16 are
For example, a honeycomb catalyst or a pellet catalyst is used. The honeycomb catalyst is obtained by coating the inner wall surface of a cordierite honeycomb catalyst carrier forming honeycomb cells with an alumina layer or the like, and further supporting a nickel layer or the like thereon by an impregnation method. The reaction tube 1 is made of cylindrical stainless steel. The heating furnace 2 is, for example, a combustion burner.

The raw material gases, whose main components are methane and water vapor, are introduced from the inlet of the reaction tube 1. The outer wall temperature of the reaction tube 1 is heated to, for example, 900 ± 100 ° C. by the heating furnace 2.
While the raw material gas first passes through the first catalyst section 12,
The chemical reaction shown in (1) occurs. (Reforming reaction) CH ₄ + H ₂ O → CO + 3H ₂ (Endothermic reaction) (1) Since the reaction represented by the formula (1) is an endothermic reaction, the first catalyst portion 12 that causes the first catalytic reaction is The temperature drops sharply. The raw material gas that has passed through the first catalyst portion 12 is the reaction tube 1
The gas temperature is gradually increased by heat transfer from the outer peripheral portion of the gas, and when the temperature rises, the gas flows into the next second catalyst portion 13. In the second catalyst section, the endothermic reaction represented by the formula (1) proceeds again and the gas temperature drops. Since the reforming reaction accompanied by the rise and fall of this temperature is always performed at a temperature exceeding the carbon deposition temperature Tc, carbon deposition does not occur.

In this way, the raw material gas is converted into the catalyst parts 12, 1
The reforming reaction progresses every time when the gas passes through 3, 14, 15 and 16, and the fuel reforming of the raw material gas is favorably performed after flowing out of the reaction tube 1, and CO, H ₂ , CO ₂ , CH ₄ , H ₂ O etc. are discharged. This exhaust gas is sent to a CO shift converter (not shown). Next, as described above, the carbon deposition temperature Tc
2 to 4 show specific configuration examples of the fuel reforming apparatus suitable for proceeding the reforming reaction at a temperature exceeding the temperature.

(First Embodiment) The first embodiment shown in FIG.
This is an example in which the disk-shaped first catalyst portion 22 is provided inside the straight reaction tube 21, and the second catalyst portion 23 is arranged at a distance from the first catalyst portion 22. The raw material gas flows in the direction of the white arrow and passes through the first catalyst portion 22 and the second catalyst portion 23. At this time, the reforming reaction proceeds.

(Second Embodiment) The second embodiment shown in FIG.
This is an example in which the reaction tube 31 is composed of a double tube of an inner tube 31a and an outer tube 31b. The heating means is provided with a heater on the outer peripheral portion of the outer tube 31b, and transfers heat from the heating source (not shown) arranged on the outer peripheral portion of the outer tube 31b to the inside of the outer tube 31b in the arrow Q direction. In addition, a heat exchange medium that transfers heat to the outer pipe side is circulated in the inner pipe 31a in the direction of the arrow indicated by the dotted line. A raw material gas is caused to flow in a doughnut-shaped flow path formed inside the outer pipe 31a on the outer side of the inner pipe 31a in a direction indicated by a white arrow. Then, the first catalyst portion 32 and the second catalyst portion 33 are arranged at a position spaced from the first catalyst portion 32 in the middle of the doughnut-shaped flow path. The raw material gas promotes the reforming reaction when passing through the first catalyst portion 32, and then the heat from the inner heat exchange medium is generated in the portion between the first catalyst portion 32 and the second catalyst portion 33. As well as receiving heat from the outside,
After being heated, it enters the second catalyst section 33, undergoes a reforming reaction, and is then discharged. In the second embodiment, since the flow path of the source gas is formed in a donut shape, heat is supplied from both sides from the radial inner side and the radial outer side, so that the heat transfer action is large, so that the reaction There is an advantage that it is easy to always keep the gas temperature above the carbon precipitation temperature.

(Third Embodiment) The third embodiment shown in FIG.
This is an example in which the reaction tube 41 is composed of an inner tube 46 and an outer tube 47, and the inner tube 46 is arranged inside an outer tube 47 having a large diameter with a bottom. The raw material gas flows in the direction of the white arrow. That is, the donut-shaped portion on the outer side of the inner pipe 46 flows downward in this figure, and after making a U-turn at the bottom, the inner pipe 46 on the inner side flows upward in the direction of the white arrow. Outside of the inner pipe 46 and the outer pipe 4
On the inner wall side of 7, a first catalyst portion 42, a second catalyst portion 43,
The third catalyst portion 44 and the fourth catalyst portion 45 are arranged at intervals. The raw material gas flows downward from the first catalyst portion 42 side, passes through the fourth catalyst portion 45, and then makes a U-turn at the bottom portion to flow upward through the inner pipe 46. On the other hand, the outer tube 47
The heating by the burner 48 or the like is performed below. Therefore, the heat supplied to the outer pipe 47 is the heat transfer due to the convection phenomenon of the combustion gas from the outside in the direction indicated by the arrow,
When the gas that has passed through the fourth catalyst portion 45 flows upward in the inner pipe 46, the gas flowing in the inner pipe 46 becomes a heat exchange medium and passes through the wall of the inner pipe 46 from the outer diameter. Heat is transferred to the inside of the outer tube 47 on the direction side. In this example, the structure has a very good thermal efficiency.

Also in the third embodiment, since the reaction gas temperature is always maintained at a temperature higher than the carbon precipitation temperature, there is an effect that a good reforming reaction proceeds. Next, experimental data are shown. (1) Catalyst part length test (1) This test is an experiment to investigate the relationship between the catalyst part length and the reaction conversion rate. Experimental data are shown in FIG.

As experimental conditions, it has been found in the experiments so far that most of the catalytic reaction occurs on the inlet side of the catalyst portion and the catalytic reaction does not easily occur on the outlet side of the catalytic portion as the temperature decreases. Therefore, one purpose is to know what range is the most efficient catalyst section length. Here, the relationship between the gas flow rate, the catalyst section length, and the reaction conversion rate was investigated.

The experimental conditions are as follows. Catalyst shape: Honeycomb 20mi160cpi ² , 50mmφ × (10,20,3
0,40,50mmL) Gas flow rate: SV value 2000,5000,8000hr ^-1 (catalyst layer volume 50
φ × 200 conversion) Gas composition: H ₂ O / CH ₄ = 4 Preheating furnace temperature: 500 ° C. Outer wall temperature of reaction tube: 900 ° C. Reaction conversion rate: Calculated from gas chromatography analysis results.

[0024]

[Table 1]

The experimental results are shown in FIG. 5 and Table 1. As can be seen from the results of this experiment, there was almost no change in the reaction conversion rate when the catalyst portion length was 30, 40, or 50 mm. It has been found that when the length of the catalyst portion is relatively short such as 10 and 20 mm, the reaction conversion rate tends to decrease as the length of the catalyst portion decreases. (2) Catalyst Length Test (Part 2) This test investigates the relationship between the diameter of the reaction tube, the gas flow rate, and the length of the catalyst section until the temperature at the center of the reaction tube drops to the carbon deposition temperature Tc. It is an experiment. Figure 1 shows the experimental data
3 shows.

The experimental conditions are as follows. Reaction tube diameter: 20mmφ, 50mmφ Gas flow rate: SV value 5000, 10000hr ^-1 (catalyst layer volume 50φ x
200 conversion) Gas composition: H ₂ O / CH ₄ = 2.5 Preheating furnace temperature: 500 ° C Reaction tube outer wall temperature: 900 ° C

[0027]

[Table 2]

The experimental results are shown in FIG. 13 and Table 2. As can be seen from the results of this experiment, the length of the catalyst portion until the temperature of the central portion of the reaction tube falls to the carbon deposition temperature Tc is such that the smaller the diameter of the reaction tube, the center of the reaction tube relative to the distance from the inlet of the catalyst portion. The lowering of the part temperature is small, and the length of the catalyst part until the temperature of the central part of the reaction tube reaches Tc becomes long. However, when the diameter of the reaction tube is reduced, the number of reaction tubes for treating a certain amount of gas increases, so that the practical reaction tube diameter is 20 mmφ or more. When the SV value is increased, the temperature of the central portion of the reaction tube is prevented from lowering, and the length of the catalyst portion until the temperature of the central portion of the reaction tube falls to the carbon deposition temperature Tc becomes long. However, when the SV value is increased, the reaction conversion rate becomes low. When the ratio of H ₂ O / CH ₄ is increased, the carbon deposition temperature Tc decreases, but the amount of heat required to heat the excess steam increases, so that the operating efficiency decreases.

On the other hand, the reaction tube diameter is 20 mm and the SV value is 100.
Under the condition of 00 hr ^-1 , if the catalyst portion length is 100 mm or less, the reforming reaction can be performed without lowering the temperature of the central portion of the reaction tube to the carbon deposition temperature Tc or less. From the above results, it can be understood that shortening the catalyst layer length is a practical method for preventing carbon ℃ precipitation.

(3) Temperature distribution test of the catalyst part The temperature change of the catalyst part was observed for the catalyst part lengths of 10 mm and 40 mm. The result is shown in FIG. The gas flow rate was SV = 5000 hr ⁻¹ . As can be seen from FIG. 6, whether the catalyst portion length is 10 mm or 40 mm, there is a rapid temperature drop of about 300 ° C. in the central portion temperature within the axial distance of 10 mm from the catalyst portion inlet. . When the catalyst portion length is 10 mm, the temperature rises after the catalyst portion outlet, that is, the catalyst portion length is 10 mm. On the other hand, when the catalyst portion length is 40 mm, the temperature further continues to drop, and the temperature rises from the catalyst outlet surface, that is, the position where the catalyst portion length is 40 mm. Moreover, immediately after the outlet of the catalyst section, the temperature rises rapidly in all cases. Therefore, the distance between the outlet surface of the first catalyst portion and the inlet surface of the second catalyst portion should be long enough to reach a temperature at which the gas temperature is sufficiently high, that is, a temperature at which carbon precipitation is unlikely to occur. it is conceivable that.

(4) Temperature Distribution in Reaction Tube (No. 1) Next, FIG. 7 shows the results of experiments on the temperature distribution in the central portion of the reaction tube. This experimental condition is that the temperature of the outer wall of the reaction tube: 90
It was set to 0 ° C. and SV = 5000 hr ⁻¹ (catalyst layer length 200 mm conversion). The reaction conversion rate was 84%. The experimental results are shown in FIG. 7.

As can be seen from FIG. 7, there is a large temperature difference between the inlet portion and the outlet portion of the first catalyst portion 12. Further, it can be seen that also in the second catalyst portion 13, there is a temperature difference between the inlet portion and the outlet portion. However, it is determined that the temperature drop in the first catalyst section 12 is remarkable. (5) Temperature Distribution of Reaction Tube (Part 2) Next, the result of the experiment conducted on the apparatus used in the experiment shown in FIG. 7 and further provided with the heat transfer promoter 18 downstream of the first catalyst section 12 Is shown in FIG.

The apparatus used as the heat transfer accelerator here is specifically a kind of mixer, that is, a static mixer having a shape for promoting gas mixing by the flow of gas. The temperature distribution in the central portion of the reaction tube in the fuel reformer provided with the heat transfer promoter 18 shown in FIG. 8 is as shown in FIG. Here, the experimental conditions are the outer wall temperature of the reaction tube: 900 ° C., S
V = 5000 hr ⁻¹ (catalyst layer length 200 mm conversion). The reaction conversion rate was 88%.

As can be seen from FIG. 8, by providing the heat transfer promoter 18, the heat from the heating furnace 2 is efficiently transferred to the raw material gas, and the temperature of the raw material gas at the inlet portion of the second catalyst portion 13 is increased. It is about 120 ° C. higher than in FIG. 7.
Therefore, it is considered that the reforming reaction in the second catalyst portion 13 is promoted and the reaction conversion rate is improved. (6) Temperature distribution of reaction tube (No. 3) Next, FIG. 11 shows an example in which the apparatus used in the experiment shown in FIG. 8 is developed. In the device used in the experiment shown in FIG. 11, the first
The first heat transfer promoting body 18 is provided between the catalyst section 12 and the second catalyst section 13, and the second heat transfer promoting section is provided between the second catalyst section 13 and the third catalyst section 14. Body 19 was provided. As the heat transfer accelerator, the same one as in the experiment shown in FIG. 8 was used.

The temperature distribution at the center of the reaction tube in the fuel reformer shown in FIG. 11 is as shown in FIG. Here, the experimental conditions are: outer wall temperature of reaction tube: 900 ° C., SV = 500
It was set to ⁰ hr ⁻¹ (converted to a catalyst layer length of 200 mm). The reaction conversion rate was 89%. As can be seen from FIG. 11, by alternately providing the plurality of catalyst parts and the plurality of heat transfer promoting parts, a good reaction conversion rate was obtained without lowering the temperature of the raw material gas to Tc or lower. Further, from FIG. 11, as compared with the temperature difference between the inlet portion and the outlet portion of the first catalyst portion 12,
It can be seen that the temperature difference between the second catalyst portion 13 and the third catalyst portion 14 is gradually decreasing. It is considered that this is because as the reaction conversion rate increases, the number of reforming reactions that proceed in the catalyst portion decreases and the heat absorption amount decreases.

(7) Temperature distribution in reaction tube (Part 4) From the results of the experiment shown in FIG. 11, it is understood that the temperature decrease of the raw material gas per length of the catalyst portion becomes smaller toward the downstream side of the raw material gas flow. . Therefore, it is expected that the axial length of the catalyst portion can be increased without depositing carbon toward the downstream side of the raw material gas flow.

In the apparatus used in the experiment shown in FIG. 11,
FIG. 12 shows an example in which the axial length of the catalyst portion on the downstream side of the raw material gas flow is made longer than the axial length of the catalyst portion on the upstream side. In the apparatus shown in FIG. 12, the axial length of the catalyst portion is 20 mm in the first catalyst portion 12 and 2 in the second catalyst portion 13.
5 mm, and 30 mm in the third catalyst portion 14. 12
The temperature distribution in the center of the reaction tube in the fuel reformer shown in
This is as shown in FIG.

Here, the experimental conditions are as follows: outer wall temperature of reaction tube: 90
It was set to 0 ° C. and SV = 5000 hr ⁻¹ (catalyst layer length 200 mm conversion). The reaction conversion rate was 93%. From the results of the experiment shown in FIG. 12, even if the lengths of the second catalyst portion 13 and the third catalyst portion 14 are made longer than those of the experiment shown in FIG.
It can be seen that the minimum temperature of the raw material gas in the entire reaction tube is the same as in the experiment shown in FIG. Further, since the length of the catalyst portion was increased, a good reaction conversion rate of 93% was obtained.

As described above, according to the present invention, the temperature drop amount due to the endothermic reaction of the reaction gas can be reduced by providing the first catalyst portion and the second catalyst portion with a space to reduce the length of the catalyst portion. The reaction gas is discharged from the outlet of the catalyst section before it falls to the carbon deposition temperature, and by repeating this operation, reforming of the fuel is promoted, carbon deposition is suppressed, and the efficiency of the fuel cell system is improved. can do.

The present invention can be applied to a device other than the fuel cell system, for example, a hydrogen generator.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating the principle of a fuel reformer of the present invention.

FIG. 2 is a schematic perspective view showing a specific example of the reaction tube structure according to the first embodiment of the present invention.

FIG. 3 is a schematic perspective view showing a specific example of a reaction tube structure according to a second embodiment of the present invention.

FIG. 4 is a schematic perspective view showing a specific example of a reaction tube structure according to a third embodiment of the present invention.

FIG. 5 is a data diagram showing experimental data of the present invention.

FIG. 6 is a data diagram showing experimental data of the present invention.

FIG. 7 is a data diagram showing experimental data of the present invention.

FIG. 8 is a data diagram showing experimental data of the present invention.

FIG. 9 is a data diagram showing experimental data of a conventional example.

FIG. 10 is a diagram showing a temperature distribution in a reaction tube of a conventional example.

FIG. 11 is a data diagram showing experimental data of the present invention.

FIG. 12 is a data diagram showing experimental data of the present invention.

FIG. 13 is a data diagram showing experimental data of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tube 2 Heating furnace (heater) 5, 6, 7, 8 Heat transfer promotion section 12, 13, 14, 15, 16 Catalyst section 18, 19 Heat transfer promotion body 21 Reaction tube 22, 23 Catalyst section 31 Reaction tube 32, 33 catalyst section 41 reaction tube 42, 43, 44, 45 catalyst section 46 inner tube 47 outer tube

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshimi Ezaki, 1 20-20 Kitakanyama, Odaka-cho, Midori-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. Electric Power Research Laboratory (72) Inventor Masatoshi Hattori Midori, Nagoya, Aichi 20, Kitakanyama, Otakacho, Tokyo

Claims (11)

[Claims] 1. A reaction tube through which a raw material gas flows, a first catalyst section arranged in the reaction tube, a second catalyst section spaced apart from the first catalyst section, A heater for heating the reaction tube, and an axial length of the catalyst part so that the temperatures in the first catalyst part and the second catalyst part are maintained at a temperature at which carbon deposition is avoided. A fuel reforming device having a catalyst layer in which is set. 2. The fuel reformer according to claim 1, wherein the catalyst portion is a honeycomb catalyst. 3. The fuel reformer according to claim 1, wherein the catalyst portion is a thin layer within a predetermined length in the flow direction. 4. The fuel reformer according to claim 1, wherein the catalyst portion has a donut shape. 5. The fuel reformer according to claim 4, wherein the donut-shaped catalyst portion is unidirectionally gas-circulated. 6. The fuel reformer according to claim 4, wherein the gas is allowed to flow through the donut-shaped catalyst portion and then the gas is passed through the inner hole portion of the donut-shaped catalyst portion. 7. The fuel reformer according to claim 1, wherein the catalyst layer has a plurality of the catalyst parts and a plurality of heat transfer promoting parts between the catalyst parts adjacent to each other. 8. The fuel reformer according to claim 1, wherein the axial length of the catalyst portion is relatively long in the axial length of the downstream catalyst portion. 9. The fuel reformer according to claim 1, wherein a heat transfer promoting member is provided in a heat transfer promoting unit between adjacent catalyst units. 10. The fuel reformer according to claim 1, wherein the heater is set so that the outlet side of each catalyst portion receives a relatively larger amount of heat than the inlet side. 11. The fuel reformer according to claim 10, wherein the heater is one or more heaters of a heat transfer heater and a burner.