JPS6126956B2 - - Google Patents

Description

Detailed Description of the Invention The present invention involves reforming hydrocarbon gas such as natural gas, propane gas, or hydrocarbon gas obtained by heating liquid hydrocarbons to mainly contain hydrogen and carbon dioxide gas. The present invention relates to a relatively small and simple reformer that converts inorganic gas into inorganic gas.

Conventionally, this type of reaction has been mainly carried out industrially, with a reformer installed as part of a large-scale plant. Therefore, when heating the catalyst layer, it is not often the case that the catalyst layer is directly heated with a heater or the like, but the raw material water (steam) or hydrocarbon gas is usually heated and guided to the catalyst layer. In addition, there is an example of a somewhat small-sized device that uses a heater directly, as shown in FIG. In this conventional structure, a heater 2 is placed on the inner surface of a reaction tube 1, a steam reforming catalyst body 3 is installed in such a way that the outer periphery is in contact with this heater 2, and heat is applied from the outside surface of this reforming catalyst body 3. I have been made to do so. Therefore, while the heat from the heater 2 is transmitted to the steam reforming catalyst body 3, most of the heat is transmitted through the reaction tube 1 and escapes to the outside. Although the heat escaping to the outside can be recovered by preheating the raw material gas to some extent, the recovery rate is low and the structure is quite wasteful.

The present invention aims to eliminate these conventional drawbacks, and its purpose is to make the reforming reactor a relatively small and simple reformer, and to minimize the energy required to heat the reforming catalyst.

In order to achieve this objective, the present invention incorporates a heater section in the center of the reaction tube, places a completely sealed ceramic heater rod, and places a catalyst body around it, so that heating starts from the center of the catalyst body. Furthermore, the structure is such that the heat escaping to the outside of the reaction tube is used to heat the hydrocarbon gas or steam before entering the reforming catalyst.

With this configuration, the energy consumption is approximately 2/3 compared to the conventional method of heating from the outer periphery of the catalyst body, and the device itself can be made more compact.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, a reaction tube 1 has a cylindrical shape and is made of alumina or mullite. A heater 2 is embedded in the center of the reaction tube 1, and a ceramic rod 4 made of alumina or mullite is provided. Inside of reaction tube 1 and ceramic rod 4
In between, a steam reforming catalyst body 3 made of an inorganic heat-resistant material with a plurality of pores 5 is built in, using a catalyst-supported material such as alumina, silica, titania, chromia, and dolomite. Furthermore, a reaction gas take-off pipe 6 is connected to the reaction tube 1 for taking out the generated reformed gas to the outside. An outer circumferential tube 7 covers the outer periphery of the reaction tube 1 so as to wrap around the entire reaction tube 1, and a part of the outer circumferential tube 7 wraps around the outside of the reaction gas extraction tube 6 to form a double outer tube 8. It branches off from a reaction gas take-off pipe 6 and is connected to an introduction pipe 9 that connects a hydrocarbon and steam supply source (not shown) to the reformer. A heat insulating material 10 is wrapped around the outside of these outer circumferential tubes 7 in order to effectively utilize heat. The heater 2 built into the wall of the ceramic rod 4 is connected to the lead wire 1.
1 and pass through the wall of the ceramic rod 4,
Its end is taken out to the outside and connected to a power source 12.

In FIG. 3, the heater 2 is printed in the form of a rectangle on the surface of a cylindrical ceramic rod, and is covered with a thin ceramic plate of the same quality. The end of the heater 2 is directly connected to the lead wire 11, which is made of the same material as the heater 2, but has a larger current cross-sectional area, so the electrical resistance is small and there is almost no heat generation in this part.

Next, the operation of the gas reformer having the above configuration will be described.

To operate this gas reforming device, first, the heater 2 in the ceramic rod 4 is energized to heat the steam reforming catalyst body 3 to a predetermined temperature. After the steam reforming catalyst body 3 reaches the set temperature, hydrocarbon gas and steam flow out through the introduction pipe 9. These raw material gases enter the double-walled outer tube 8 and enter the outer periphery of the reaction tube 1 while absorbing the heat received from the reaction gas take-off tube 6. In this case as well, the raw material gas is generated from the heat of the generated gas in the reaction tube 1 and the heater 2,
The reaction tube 1 is sufficiently preheated by the heat transferred to the outer periphery of the wall. The preheated raw material gas is transferred to reaction tube 1.
The generated gas enters the inside, passes through the steam reforming catalyst body 3, and is taken out to the outside through a reaction gas take-off pipe 6 connected to the end of the gasification reaction tube 1. The reaction gas take-off pipe 6 is a double pipe halfway, and heat exchanges there, heating the raw material gas supplied from the outside, and cooling itself.

Furthermore, since the heater 2 of the gas reformer according to the invention is housed inside a cylindrical ceramic and is made of ceramic such as alumina, the degree to which hydrocarbons are thermally decomposed and carbon is precipitated is higher than that of iron, copper, or nickel. It is considerably less than when a normal metal surface touches. Furthermore, since the heater 2 is completely buried inside the ceramic, it does not come into contact with the harsh atmosphere during hydrocarbon reforming, so that the heater life can be maintained for a long time.

The effects of the gas reformer according to the present invention are as follows.

(1) Since the heater is located in the center of the catalyst layer, most of the energy can be used for steam re-forming of hydrocarbons, which is the original purpose, and the heat escaping to the outside is used to preheat the raw material gas. This reduces heat loss.

(2) Since the heater is buried inside the ceramic, the amount of tar and carbon deposited in the heater part is small, making maintenance of the device easy. Furthermore, there is no need to worry about carburization due to carbon or hydrogen embrittlement due to generated hydrogen.

(3) The reaction tube can be made considerably smaller, allowing a compact reforming reaction device.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a conventional hydrocarbon reformer, Fig. 2 is a side sectional view of a hydrocarbon reformer which is an embodiment of the present invention, and Fig. 3 is a sectional view of the main part of the reaction tube of the same equipment. It is a diagram. 1... Reaction tube, 2... Heater, 3... Steam reforming catalyst body, 4... Ceramic rod, 7
...Peripheral tube.

Claims (1)

[Scope of Claims] 1. A reaction tube for reforming hydrocarbon gas and water vapor on a reforming catalyst and converting it into hydrogen or a lower molecular weight hydrocarbon, and a heater for heating the reforming catalyst, and the An inorganic heat-resistant ceramic rod located approximately in the center of the reaction tube, and an outer peripheral tube made of a heat-resistant metal or inorganic heat-resistant ceramic located at the outer periphery of the reaction tube and having a gap with the outer surface of the reaction tube. Hydrocarbon reformer. 2. The hydrocarbon reforming method according to claim 1, wherein hydrocarbon gas and steam are preheated between the outer periphery of the reaction tube and the outer circumferential tube, and then passed into the reaction tube and subjected to steam reforming on a reforming catalyst body. quality equipment.