JPH06229530A - Catalytic reactor - Google Patents

Abstract

PURPOSE:To supply a small-sized and efficient catalytic reactor. CONSTITUTION:A catalytic reactor comprises reaction product passages 15, 16, a reaction product inlet 10, an outlet 11, and a catalyst 12 having a heating part 13 therein and permeability on the way of the passage. With the structure, diffusion of radiation heat from a heater is prevented in a limited volume of the relatively-small-sized reactor to suppress input of catalytic heating to a necessary minimum limit, the heat is absorbed to the catalyst itself to effectively heat it, mixed gas of unburnt gas of fuel, malodorous harmful gas, etc., the air can be smoothly reacted to be discharged as harmless odorless gas.

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 air, gas components such as fuel, harmful components and malodorous components, and air, and discharging it as harmless and odorless gas.

[0002]

2. Description of the Related Art Catalytic reactors, which are large in size and small in size, have a wide range of catalytic reactors from air-oxidizing unburned gas, harmful component gas, and malodorous component gas contained in fuel exhaust gas to produce harmless and odorless gas. It has been put to practical use. The catalyst used in the catalytic reactor includes platinum, heavy metal-based compounds such as palladium-based noble metal-based metal manganese, and perovskite-based composite oxides, which are pellet-shaped, mat-shaped, net-shaped,
It is used after being formed into a honeycomb shape or the like. In the case of reacting a gas, it is often used by forming it into a honeycomb shape having a small ventilation resistance and a large mechanical strength. Since these oxidation catalysts have low room temperature reactivity, it is necessary to set the reaction gas temperature or the catalyst temperature to about 200 ° C. or higher to increase the reactivity, and to set the reaction gas temperature to about 400 ° C. for sufficient reaction. When the gas was not at a sufficient temperature, it was necessary to heat it with a heater such as a heater.

Therefore, conventionally, the catalytic reactor has generally been constructed as shown in FIG. The configuration will be described below with reference to FIG.

As shown in the figure, the main body 1 of the catalytic reactor comprises a reactant inlet 2, an exhaust gas outlet 3 and gas passages 4 and 5, and a catalyst-supported air-permeable catalyst is provided in the middle of the passages. A medium 6 is provided and a heater 7 is provided outside the catalyst body. Further, the main body 1 is entirely covered with a heat insulating material 8.

In the above structure, the heater 7 is operated to heat the catalyst body 6 and the reaction gas is introduced from the reactant inlet 2.
The reaction gas passes through the gas passage 4 and the catalyst body 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 the conventional structure as described above, when the temperature of the reaction gas when passing through the catalyst is increased to 200 ° C. or more in order to enhance the catalytic reactivity, when the catalytic reactor itself is relatively small, Covering with a heat insulating material to reduce the heat dissipation loss at the time of heating causes a problem that the surface area becomes large and conversely the heat dissipation loss increases, and the necessary input for heating the catalyst becomes excessive. . In addition, the catalytic reactor itself becomes large. To heat the reaction gas temperature to about 400 ° C. in order to obtain more sufficient reactivity within the limited volume of a relatively small catalytic reactor, the temperature of the heater is 60
Although it is necessary to heat up to about 0 ° C. to 800 ° C., heat is mainly transferred by radiation in this temperature range, and radiation heat is not used in the above-described conventional configuration, resulting in a large radiation loss.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a catalytic reactor having a compact structure with a minimum heat input for heating the catalyst.

[0008]

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

[0009]

According to the present invention, by adopting the above-mentioned structure, that is, the structure in which the catalyst body is placed around the heater, the radiation rays generated from the surface of the heater are blocked to prevent scattering to other parts, and the touch The medium itself absorbs the radiation and is heated.
Further, the reaction gas is heated from the surface of the catalyst body by convection.

[0010]

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

As shown in the figure, a main body 9 is provided with a reaction gas inlet 10 and an exhaust gas outlet 11, and a honeycomb structure (monolith) is shown in the middle of a passage through which a gas flows from the inlet to the outlet, for example. The surface of the carrier made of cordierite-based ceramics described in (1) above is wash-coated with γ-alumina to provide a catalyst body 12 carrying a platinum-based precious metal catalyst. As shown in FIG. 4, the catalyst body may be formed by bending a sheet-shaped ceramic or the like and used as a carrier, and it is desirable that the catalyst or the heat-resistant metal be freely processed to have air permeability. The catalyst body 12
Heater 1 with hollow heat generating part 13a
Equipped with 3. Further, the main body 9 is entirely covered with a heat insulating portion 14 in order to prevent heat diffusion. The heat insulating portion 14 may have a material structure such as ceramic fiber or glass fiber, or a vacuum heat insulating structure.

After heating the catalyst 12 to a predetermined temperature by operating the heater, a reaction gas in which unburned components, malodor, harmful gas and air are mixed is introduced into the main body 9 through the reaction gas inlet 10. The reaction gas enters the passage 15, and the gas itself is preheated by radiation from the heater 13 and the like, and then passes through the catalyst body 12 having a sufficiently raised temperature. At this time, an oxidation reaction occurs on the surface of the catalyst body 12,
It is converted into oxides such as carbon dioxide and water, passes through the passage 16 and is discharged from the exhaust gas outlet 11 as harmless and odorless gas. In this example, the catalyst temperature was set to 400 ° C., and a gas containing 0.1% concentration of carbon monoxide gas was mixed in the air.
When the catalyst having a volume of 50 cc was passed through at a flow rate of NL / min, the reaction rate was about 100%. It is more effective to control the heater 13 using an electric heater by detecting the temperature with a temperature detector provided inside the catalyst body 12 or on the downstream side thereof so that the temperature of the reaction section is appropriately maintained and the reaction proceeds. 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 heater inside.

Another embodiment of the present invention will be described below with reference to FIG. The same components as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted.

An outer passage 17 for the 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 body 1.
2 is introduced into the upstream passage 15. After that, the procedure is similar to that of the above-described embodiment, but in this embodiment, when the low-temperature reaction gas introduced from the reactant inlet 10 by the heat exchange section 18 passes through the outer passage 17 and before passing through the catalyst body 12, Heat is exchanged with the heat of. With this configuration, by effectively utilizing the waste heat and preheating, the heating load of the heater 13 can be reduced and the heating efficiency can be further improved as compared with the above embodiment. Although the heat exchange section 18 is made of a metal plate in the present embodiment, it is also effective to have a finned configuration, a shell-and-tube type configuration, or the like. Also, the catalyst body 12 and the outer passage 1
A space between 7 and 7 may be adiabatic if necessary.

[0016]

According to the present invention, the catalyst body is arranged around the heater to block radiation emitted from the surface of the heater by the catalyst body itself to prevent radiation to other parts, and at the same time, the catalyst body itself It can absorb the radiation and be effectively heated. In this way, it is possible to provide a catalytic reactor which has a small heat radiation loss and can minimize the heat input for heating the catalyst. Furthermore, since a catalytic reactor having a simple structure and a small size is realized, an inexpensive catalytic reactor can be manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a catalytic reactor showing an 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 vertical cross-sectional view of main parts of a catalytic reactor in a conventional example.

[Explanation of symbols]

12 catalyst body 13 heater 20 honeycomb-shaped catalyst body 21 heater 22 catalyst body using a bent sheet-shaped ceramic or the like as a carrier 23 heater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiro Suzuki, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A catalytic reactor comprising a reactant passage and a breathable catalyst body provided with a heater inside the passage. 2. The catalytic reactor according to claim 1, further comprising a heat exchange section for exchanging heat between the upstream passage and the downstream passage of the reactant passage. 3. The catalytic reactor according to claim 1, wherein the catalytic reactor comprises a catalyst body having a honeycomb structure mainly composed of a ceramic material or a metal material. 4. The catalytic reactor according to claim 1, wherein a catalyst body is used which comprises a carrier having a structure in which a sheet-shaped ceramic material or metal material is bent into a corrugated plate shape.