JPH0324967Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a catalytic combustor, and more particularly to a catalytic combustor suitable for preventing deformation and damage of supports for granular combustion catalysts due to heat.

(Prior Art) Taking a fuel cell reformer (hydrogen gas generator) as an example, a conventional catalytic combustor is used to heat the reaction tube 3 of the hydrogen generator, as shown in FIG. , a premixed gas of fuel gas and air is combusted in a combustion catalyst layer 4 filled between reaction tubes 3, and a plate-shaped porous body or honeycomb provided at the bottom of the cylindrical device body 1. A support 5 consisting of a shaped body, a wind box 9 provided at the bottom of the support 5, a combustion catalyst layer 4 filled and supported on the support 5, and a heat transfer promoting particle layer 6 provided above the support 5. , a reaction tube 3 inserted into the combustion catalyst layer 4, a reforming catalyst 2 filled in the reaction tube 3, and a bottom part of the reaction tube inserted into the reforming catalyst 2. A premixed gas nozzle 8 provided in the reformed gas pipe 3 and the wind box 9,
It is composed of a source gas nozzle 11 for supplying gas through the reforming catalyst 2, and a reformed gas discharge nozzle 12 provided in the reformed gas chamber 12A above the reformed gas pipe 3A. In such a device, a premixed gas containing fuel is preheated to approximately 300°C and is supplied from a nozzle 8 into a wind box 9, passes through a honeycomb-shaped or perforated plate-shaped support 5, and enters the combustion catalyst layer 4. After burning at about 1000-1200°C and heating the reaction tube 3, the combustion exhaust gas is discharged from the exhaust gas outlet 10.

(Problems to be solved by the invention) However, such a catalytic combustor has the following drawbacks.

(1) Since the support 5 is in direct contact with the combustion catalyst layer 4, the temperature difference in the thickness direction of the support 5 is large.
Supports become thermally deformed or damaged. Figure 5 shows
FIG. 6, a detailed view of the combustion device near the catalyst layer, shows the temperature distribution from the wind box to the catalyst layer, and it can be seen that there is a large temperature difference in the thickness direction of the support.

(2) Even if mullite, which has excellent heat resistance (maximum operating temperature 1650°C), is used as the material for the support 5, it may be damaged due to its poor thermal shock resistance.

(3) When cordierite or the like, which has relatively excellent thermal shock resistance, is used as the material for the support 5, the operating temperature limit is approximately 1200°C, and the support surface is particularly susceptible to deformation and breakage due to heat.

It is an object of the present invention to provide a catalytic combustor that eliminates the drawbacks of the prior art described above and prevents thermal deformation and damage of the support due to direct contact with the combustion catalyst layer.

(Means for Solving the Problems) In short, the present invention provides a heat-resistant particle layer between the particulate combustion catalyst layer and the support so that the heat of the combustion part is not directly transmitted to the support. That is, the present invention provides a catalytic combustor having a granular combustion catalyst for combusting gas containing fuel and oxygen and a support for supporting the combustion catalyst. A particle layer is arranged to prevent the support from being thermally deformed and damaged due to direct contact with the high-temperature catalytic combustion section.

In this invention, the heat-resistant particle layer is generally made of alumina particle layer, etc., which has a combustion temperature (for example, 1200℃).
A particle layer having the above heat resistance is used.

(Example) FIG. 1 shows an example in which the catalytic combustor of the present invention is applied to a reforming furnace for fuel cells. This reformer has the same configuration as the apparatus shown in FIG. 4 except that a heat-resistant particle layer 7 is provided between the support 5 and the combustion catalyst layer 4. That is, this device includes a reformer main body 1,
A reaction tube 3 filled with a reforming catalyst 2, a granular combustion catalyst layer 4 for burning premixed gas, its support 5, a heat transfer promoting particle layer 6, a heat-resistant particle layer 7 according to the present invention, etc. It consists of

In the apparatus having the above configuration, the premixed gas nozzle 8
The premixed gas of fuel gas and air supplied into the wind box 9 from Burns at ℃. Above the tip of the reaction tube 3 are heat insulation promoting particles 6.
The combustion gas heats the reaction tube 3 while passing through the heat transfer promoting particle layer, and is discharged from the exhaust gas nozzle 10 at about 550°C.

On the other hand, the mixed gas of city gas and steam enters the reaction tube 3 from the raw material gas nozzle 11, and enters the reforming catalyst layer 2.
Inside the tube, it is heated to about 800° C. by heat transfer from outside the tube, becoming hydrogen-rich reformed gas, which is discharged from the reformed gas nozzle 12 and used as fuel for the fuel cell.

As mentioned above, the premixed gas of fuel gas and air is
Combustion occurs at approximately 1200°C within the combustion catalyst layer 4, and between the combustion catalyst layer and the honeycomb-shaped support 5 is a heat-resistant particle layer 7 made of alumina with a heat-resistant temperature of 1500°C according to the present invention, as shown in FIG. , the support 5 does not come into direct contact with the high-temperature combustion catalyst layer 7 and is thermally protected.

Figure 3 shows the temperature distribution in the axial direction near the combustion section of the reformer. The temperature distribution in the thickness direction within the support 5 is made uniform for the following reason. That is, heat radiation from the combustion catalyst layer 4 is prevented by the heat-resistant particle layer 7, the contact area between the heat-resistant particles and the support is small, and there is almost no conductive heat transfer, and the premixed gas from below This is because the support is always cooled. For the reasons stated above, the temperature distribution in the thickness direction of the support 5 is almost non-uniform, and the temperature is constant, for example, about 300°C.

In addition, as shown in FIG. 3, a temperature distribution with a steep gradient occurs within the heat-resistant particle layer 7, but since it is in the form of particles, a temperature distribution occurs; however, since it is in the form of particles,
No deformation or damage occurs due to thermal stress based on temperature distribution. In addition, fuel cell reformers frequently start up and stop at high speeds, so the support must have thermal shock resistance.Since it is used at a low temperature of approximately 300°C, SUS, which has excellent thermal shock resistance, is used. It is also possible to use materials such as wood.

The catalytic combustor of the present invention can be widely applied not only to reforming reactors for fuel cells but also to other combustion devices in which catalyst particle supports are heated to high temperatures.

(Effects of the invention) According to the invention, by providing a heat-resistant particle layer on the top of the support that directs the combustion catalyst layer, it is possible to prevent the support from deformation and damage due to heat, and therefore it can be used as a support material. Materials with low heat resistance can also be used.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the catalytic combustor according to the present invention applied to a reformer, Figure 2 is a detailed view of the combustion catalyst support in Figure 1, and Figure 3 is the part shown in Figure 2. FIG. 4 is a cross-sectional view of a combustion catalyst combustor according to the prior art, and FIG. 5 is a diagram showing the temperature distribution in the axial direction of
FIG. 4 is a detailed view of the combustion catalyst support portion, and FIG. 6 is a diagram showing the temperature distribution in the axial direction of the portion shown in FIG. 5. 1... Catalytic combustor (reformer) main body, 2... Reforming catalyst, 3... Reaction tube, 4... Combustion catalyst layer, 5...
... Support, 6 ... Heat transfer accelerator particles, 8 ... Premixed gas nozzle, 9 ... Wind box, 10 ...
Exhaust gas nozzle, 11... Raw material gas nozzle, 12...
...Reformed gas nozzle.

Claims (1)

[Scope of utility model registration request] In a catalytic combustor having a granular combustion catalyst for burning a gas containing fuel and oxygen and a support for supporting the combustion catalyst, a heat-resistant particle layer is arranged between the combustion catalyst particle layer and the support, A catalytic combustor characterized by preventing thermal deformation and damage of a support due to direct contact with a high-temperature catalytic combustion part.