JP3279693B2 - Catalytic reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic reactor for oxidizing a mixed gas composed of a gas component such as fuel, harmful components and malodorous components and air and discharging the mixture as harmless and odorless gas.

[0002]

2. Description of the Related Art A wide range of catalytic reactors, from large to small, are used to convert unburned gas, harmful component gas, and odorous component gas contained in fuel exhaust gas into harmless and odorless gas by air oxidation. Has been put to practical use. Catalysts used in the catalytic reactor include platinum, heavy metal-based compounds such as palladium-based noble metal-based metal manganese, and perovskite-based composite oxides.The shapes are pellets, mats, nets, and the like.
It is used after being formed into a honeycomb shape or the like. When reacting a gas, it is often used in the form of a honeycomb having a small airflow resistance and a high mechanical strength. Since these oxidation catalysts have low reactivity at room temperature, the reaction gas temperature or the catalyst temperature needs to be about 200 ° C. or higher to increase the reactivity, and about 400 ° C. to sufficiently react. When the gas was not at a sufficient temperature, it was necessary to heat it with a heater such as a heater.

[0003] Conventionally, therefore, a catalytic reactor has generally been configured as shown in FIG. Hereinafter, the configuration will be described with reference to FIG.

As shown in FIG. 1, a catalytic reactor main body 1 comprises a reactant inlet 2, an exhaust gas outlet 3, and gas passages 4 and 5, and a catalyst-carrying catalyst having a catalyst carried in the passage. It has a medium 6 and has a heater 7 outside the catalyst body. Further, the main body 1 is entirely covered with a heat insulating material 8.

In the above configuration, the heater 7 is operated to heat the catalyst 6, and the reaction gas is introduced from the reactant inlet 2.
The reaction gas passes through the gas passage 4 and the catalyst 6. At this time, an oxidation reaction occurs, and the reaction gas is converted into a harmless and odorless gas, and is discharged from the exhaust gas outlet 3 through the gas passage 5.

[0006]

In such a conventional structure, when the temperature of the reaction gas at the time of passing the catalyst is increased to 200 ° C. or higher in order to increase the catalytic reactivity, when the catalyst reactor itself is relatively small, When covered with a heat insulating material to reduce the heat radiation loss during heating, there is a problem that the surface area becomes large and the heat radiation loss increases, and the necessary input for catalyst heating becomes excessive. . In addition, the size of the catalytic reactor itself increases. In order to heat the reaction gas temperature to about 400 ° C. in order to obtain more sufficient reactivity within a limited volume of a relatively small catalytic reactor, the temperature of the heater is set at 60 ° C.
Heating must be performed to about 0 ° C. to 800 ° C., but in this temperature range, heat is mainly transmitted by radiation, and in the above-described conventional configuration, radiant heat is not used and heat radiation loss increases.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a compact catalyst reactor having a minimum heat input for heating the catalyst.

[0008]

In order to solve the above-mentioned problems, the present invention has a structure in which a heat generating surface of a heater is covered with a catalyst and the catalyst is heated from the inside.

[0009]

According to the present invention, the above-mentioned structure, that is, a structure in which the catalyst is placed around the heater, blocks radiation emitted from the surface of the heater to prevent scattering to other parts, The medium itself is heated by absorbing the radiation.
In the catalyst, the reaction gas is heated from its surface by convection.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, a main body 9 is provided with a reaction gas inlet 10 and an exhaust gas outlet 11, and a cross section is shown in FIG. 3, for example, in the middle of a passage in which gas flows from the inlet to the outlet. The surface of the support made of cordierite-based ceramic is washed and coated with γ-alumina to provide a catalyst body 12 carrying a platinum-based noble metal catalyst. As shown in FIG. 4, the catalyst body may be one obtained by bending a sheet-like ceramic or the like as a carrier, and it is desirable that the catalyst body be made of a material such as ceramic or a heat-resistant metal and has air permeability. The catalyst body 12
Heater 1 with a hollow heat-generating part 13a
3 is provided. The main body 9 is entirely covered with a heat insulating portion 14 to prevent heat diffusion. The heat insulating portion 14 may be made of a material such as ceramic fiber or glass fiber, or may be a vacuum heat insulating structure.

After the heater is operated to heat the catalyst body 12 to a predetermined temperature, a reaction gas in which unburned components, odorous gas, harmful gas and air are mixed is introduced into the main body 9 from the reaction gas inlet 10. The reaction gas enters the passage 15, and after the gas itself is preheated by the radiation of the heater 13 or the like, passes through the catalyst body 12 which has been sufficiently heated. At this time, an oxidation reaction occurs on the surface of the catalyst body 12,
The gas is converted into oxides such as carbon dioxide and water, passes through the passage 16 as a harmless and odorless gas, and is discharged from the exhaust gas outlet 11. In the present embodiment, the catalyst temperature was set to 400 ° C., and a gas in which carbon monoxide gas was mixed at a concentration of 0.1% in air was used.
The reaction rate was about 100% when passed through a catalyst having a volume of 50 cc at a flow rate of NL / min. The heater 13 is controlled by detecting the temperature with a temperature detector provided inside or downstream of the catalyst body 12 using an electric heater, and it is more effective to keep the temperature of the reaction part appropriately and proceed the reaction. It is. At this time, it is desirable that the surface of the heater 13 has heat and corrosion resistance and is electrically insulated from the internal heater.

Hereinafter, another embodiment of the present invention will be described with reference to FIG. The same components as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

An outer passage 17 for a reaction gas is further provided outside the main body 9 of the above embodiment. A heat exchange section is provided between the outer passage 17 and the main body 9.

The reaction gas introduced from the reactant inlet 10 is first introduced into the outer passage 17, and passes through the passage 19 to form the catalyst 1.
2 Introduced into the upstream passage 15. After that, it is the same as the above embodiment, but in this embodiment, when the low-temperature reaction gas introduced from the reactant inlet 10 by the heat exchange unit 18 passes through the outer passage 17, Heat exchange with heat. In this configuration, by preheating by effectively using waste heat, the heating load on the heater 13 can be reduced, and the heating efficiency can be further improved as compared with the above embodiment. In this embodiment, the heat exchanging section 18 is made of a metal plate. However, it is also effective to adopt a finned configuration, a shell and tube type configuration, or the like. The catalyst body 12 and the outer passage 1
A heat insulating structure may be provided as needed between 7 and.

[0016]

According to the present invention, by arranging the catalyst body around the heater, radiation generated from the heater surface is cut off by the catalyst body itself to prevent radiation to other parts, and the catalyst body itself The radiation can be effectively absorbed and absorbed. In this way, it is possible to provide a catalytic reactor that has a small heat dissipation loss and can minimize the necessary heat input for heating the catalyst. Furthermore, since a catalyst reactor having a simple configuration and a small size is realized, an inexpensive catalyst reactor can be manufactured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a catalytic reactor showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a catalytic reactor showing another embodiment of the present invention.

FIG. 3 is a sectional view of a catalyst body showing another embodiment of the present invention.

FIG. 4 is a sectional view of a catalyst body showing another embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a main part of a conventional catalytic reactor.

[Explanation of symbols]

REFERENCE SIGNS LIST 12 catalyst body 13 heater 20 catalyst body having honeycomb structure 21 heater 22 catalyst body using sheet-shaped ceramic or the like bent as carrier 23 heater

Continuing from the front page (72) Inventor Kunihiro Ukai 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Jiro Suzuki 1006 Okadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56 References JP-A-49-98763 (JP, A) JP-A-4-43208 (JP, A) JP-A-4-43207 (JP, A) JP-A-56-85514 (JP, A) 48-54312 (JP, A) Fully open 63-107728 (JP, U) Fully open 57-17091 (JP, U) Fully open, 57-87933 (JP, U) Fully open, 49-115449 (JP, U.S.A.) U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23J 15/00 F01N 3/00

Claims (2)

(57) [Claims] 1. A and the passage of the reactants, the through to heat the catalyst body, the catalyst body having air permeability provided in the middle of the passage
Near the center of the plane perpendicular to the flow direction of the reactants in the path
With a rod-shaped heater parallel to the flow direction
A catalyst reactor surrounding the heat-generating surface of the heater with the catalyst body and directly transferring heat from the heater surface to the catalyst body; 2. An outer passage is provided outside the reactant passage through a wall surface, and a reactant is introduced from the outer passage and supplied to the reactant passage. 2. The catalytic reactor according to claim 1, further comprising a heat exchanging section for exchanging heat with the product passage.