JP3274424B2 - Catalytic combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus using a catalytic combustion reaction.

[0002]

2. Description of the Related Art A large number of catalytic combustion apparatuses using a catalyst having an oxidizing activity with respect to a fuel mainly composed of hydrocarbons have been proposed in the past. In particular, a large amount of radiant heat generated from the main reaction surface is used. As things to use for heating and heating,
It is roughly divided into two types. One is to supply only the fuel to the catalyst body, and to diffuse and supply the oxygen in the atmosphere on the downstream surface, where the combustion reaction is carried out and the radiant heat is directly supplied from here, and the other is to supply the fuel with the fuel. A mixture of air is supplied to cause a combustion reaction near the upstream surface of the catalyst body, and a window made of glass or the like that transmits heat rays is provided on a combustion chamber wall covering the upstream side of the catalyst body, and radiant heat is supplied therefrom. Things.

[0003]

In the above-mentioned conventional apparatus,
Although it depends on the type of fuel and the activation temperature of the catalyst, it is necessary to obtain a large amount of heat radiation with a small catalyst area and to visually check the combustion state. It is common. Therefore, although the radiation efficiency (the ratio of the amount of heat supplied and radiated to the amount of heat generated by the reaction) is high, the wavelength distribution of the radiated heat is 2
It has a peak in the near-infrared region of ３3 μm.
The wavelength component of m or more is absorbed by the glass, and although it is supplied to some extent by the secondary radiation from the glass, it becomes radiant heat mainly composed of the short wavelength component.

[0004] However, there is a problem that radiant heat having many short-wavelength components that penetrates and stimulates a pain point inside the skin to be used as a human body heating is not always comfortable.

On the other hand, it is possible to carry out a combustion reaction at a low temperature within the range of the activation temperature of the catalyst. In this case, it is possible to supply radiant heat having a long wavelength component. Continuation and stop cannot be visually confirmed, and a large-area catalyst body is required to obtain a predetermined amount of radiant heat. In particular, when a noble metal is used as an active component of the catalyst, the catalyst body becomes expensive. There was a disadvantage.

An object of the present invention is to provide a catalytic combustion device that is comfortable and allows the continuation or stop of the combustion reaction to be visually confirmed in consideration of the problems of the conventional catalytic combustion device.

[0007]

In order to solve the above-mentioned problems, in the catalytic combustion device of the present invention, a catalyst body having a large number of communicating holes is opposed to a front surface (upstream surface) of a catalyst body by using a heat-impermeable material. The heat radiating plate is provided so that the exposed area of the heat radiating plate is twice or more the surface area on the upstream side of the catalyst body.

[0008] Further, a heat exchange chamber having a radiator plate as a part of the component is provided in communication with the downstream of the combustion chamber.

Further, a discontinuous uneven structure is formed on the outer surface of the heat sink in a vertical direction.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In the practice of the present invention, in addition to a catalyst body having a large number of communication holes and having an oxidizing activity to various hydrocarbon fuels, a heat-resistant non-radiating heat ray radiating plate, an ignition device and a flow rate control device, fuel and air Or a vaporizer for liquid fuel if necessary. The catalyst body is arbitrarily selected from a honeycomb formed body of metal or ceramic, a braided body of metal or ceramic fiber, a porous sintered body, etc., on which an active component mainly containing a noble metal such as platinum or palladium is supported. Can be used. As the heat-resistant heat ray opaque material, a metal material having good heat conductivity, such as aluminum or copper, or a metal oxide sintered body such as silicon carbide or silicon nitride can be used. In general, a metal oxide thin film of iron, manganese, titanium or the like is applied on the surface to improve the emissivity. Further, as a means for controlling air or fuel, a manual valve or an electric valve, or an electromagnetic pump or the like can be used for controlling the flow rate of liquid fuel. In addition, an electric heater, a discharge igniter, or the like can be used as the ignition device. These are all means conventionally used, and other known means are also possible, and do not impair the effects of the present invention.

(Embodiment 1) FIG. 1 is a sectional perspective view of a first embodiment of a catalytic combustion apparatus according to the present invention, and FIG.
Is a radiation wavelength characteristic diagram. In FIG. 1, reference numeral 1 denotes an air-fuel mixture supply pipe for supplying an air-fuel mixture of fuel and air, reference numeral 2 denotes a combustion chamber, and reference numeral 3 denotes a catalyst body in which a white metal precious metal is supported on a ceramic honeycomb provided in the combustion chamber 2. It is. Reference numeral 4 denotes an exhaust pipe arranged on the downstream side of the catalyst body 3 of the combustion chamber 2, and 5 denotes an exhaust pipe 4
, And has a number of heat exchange fins 6 therein. Reference numeral 7 denotes an exhaust port opened on the downstream side of the heat exchange chamber 5.

A radiator plate 8 made of an aluminum plate coated with a titanium-manganese paint is provided on the surface of the catalyzer 3 so as to face the upstream surface of the catalyzer 3. It is configured to form a part of the wall surface of the chamber 5.

Next, the operation and operation of the embodiment will be described. A mixture of fuel (here, natural gas is used) and air supplied from the mixture supply pipe 1 is supplied from a lower portion of the combustion chamber 2 to an upstream surface of the catalyst body 3. The mixture is the catalyst 3
Oxidation reaction occurs near the upstream surface of the exhaust gas, and the combustion exhaust gas is discharged from the exhaust stack 4 through the communication hole of the catalyst body 3. A large amount of heat rays are radiated from the upstream surface of the catalyst body 3 which is heated and glowed by the heat of combustion, but a heat radiating plate 8 having a surface coating having a high emissivity is provided on the opposed front surface, where heat is absorbed. Then, the heat radiating plate 8 is heated and heated to radiate heat forward as secondary radiation.

Here, the heat radiation amount E (kca) from the heating surface
1 / h), the temperature of the radiation surface is T1 (K),
Is the temperature of space, T2, the emissivity of the radiation surface is e, and the area is A
(M ^Two), E = 4.88 eA [(T1 / 100)^Four
-(T2 / 100)^Four]. Upstream side of catalyst body 3
0.1m surface area (outer area)^TwoAnd emissivity 0.9
When the glow temperature is set to 850 ° C., the temperature of the heat sink 8 is set to 4
Assuming 00 ° C., radiant heat transfer from the catalyst body 3 to the heat sink 8
The calorific value is calculated as 1247 kcal / h (heat loss
Loss is ignored). On the other hand, from heat sink 8 with emissivity of 0.9
If the same amount of heat is to be radiated, the heat receiving side is set to room temperature (25
℃), the required area is about 0.7m^TwoAnd the catalyst body
This would require seven times the area of 3. Similarly, the catalyst
Assuming that the temperature of body 3 is 650 ° C., which is the limit at which red heat can be seen,
Assuming that the temperature of the heat sink 8 is 400 ° C.,
The required area is about 0.26m^TwoAnd more than twice the surface of catalyst body 3
It turns out that the product is required.

When the wavelength characteristic of the heat ray actually radiated from the apparatus was measured, the result as shown in FIG. 2 was obtained. Catalyst 3
When the temperature is about 850 ° C., the solid line A indicates the case where the conventional glass window is provided, and the one-dot chain line B indicates the case where the surface temperature of the radiation plate 8 in this embodiment is 400 ° C. Although the total amount of radiant heat represented by the integrated value over the entire wavelength range is substantially the same, the wavelength distribution is significantly different. That is, in the case of the solid line A, the wavelength of 5 μm or less is mostly used, and the ratio of far infrared rays having a wavelength of 3 μm or more remains at about 50%. On the other hand, in the alternate long and short dash line B, the wavelength peak is shifted to about 5 μm, and the ratio of far infrared rays is 9%.
It has reached nearly 0%. For this reason, the amount of radiant heat is equal,
It is possible to remarkably increase the amount of far-infrared rays that do not penetrate and stimulate the pain points on the skin while maintaining a sufficient emissivity similar to the conventional configuration. If the ratio of the far infrared rays is to be maintained at least 80% or more, the upper limit of the temperature of the heat sink 8 is about 500 ° C., while the red heat combustion of the catalyst body 3 (not shown here, 650 if you try to check it visually
Considering that the lower limit is about ° C, as is clear from the above equation, it is effective that the heat radiation area of the heat radiating plate 8 facing the upstream surface area of the catalyst body 3 is at least twice or more, Radiation efficiency is maintained while maintaining a high level of mild and comfortable heating.

Further, depending on the type of fuel, a sufficient catalytic reaction may not be obtained at a temperature of 600 ° C. or lower, as in natural gas.
The temperature of the catalyst body 3 must necessarily be used at a higher temperature, and in such a case, it can be converted to low-temperature radiation. In order to level the temperature when the area of the heat radiating plate 8 is increased, it is preferable to use a material of the heat radiating plate 8 made of aluminum or copper having good thermal conductivity or a sintered plate such as silicon carbide. Preferably, uniform heat radiation from a large area can be achieved while preventing thermal deterioration of the heat sink 8.

Further, the heat exchange chamber 5 is disposed downstream of the combustion chamber 2 by using the heat radiation plate 8 which is sufficiently larger than the shape of the combustion chamber 2, and a part of the side wall is constituted by the heat radiation plate 8. By doing so, the heat of the high-temperature exhaust gas can be further recovered here and converted into radiant heat, and the radiation efficiency can be further improved. It is also effective to arrange the heat exchange fins 6 in the heat exchange chamber 5 to form a dense channel in order to enhance the effect of the heat exchange between the exhaust gas and the radiator plate in the heat exchange chamber 5.
Also effective is a method in which the heat exchange fins 6 are made of an aluminum plate or the like having good heat conductivity, and are brought into contact with the heat radiating plate 8 to promote heat conduction.

(Embodiment 2) A second embodiment of the present invention will be described. In the present embodiment, an uneven structure is formed on the outer surface of the heat radiating plate 8 so as not to communicate in the vertical direction (vertical direction).
Is similar to the above, but uses radiation heat rays differently. Therefore, the present embodiment will be described focusing on the different points.

FIG. 3 is a cross-sectional perspective configuration diagram of the present embodiment. In FIG. 3, a multi-stage projection 18 that is continuous in the horizontal (horizontal) direction is formed on the outer surface of the heat radiating plate 8 that is installed facing the upstream surface of the catalyst body 3 in the combustion chamber 2.

In general, heat radiation from an upright high-temperature wall surface, together with radiation heat radiation to a space in front or an opposing object,
Convection heat transfer is also performed by the upward airflow flowing near the wall surface. Also on the outer surface of the radiation plate 8 heated by the heat supplied from the catalyst body 3, the heat is dissipated by the rising airflow,
This shows a tendency to increase as the area of the heat radiating plate 8 increases, and may reach 20 to 30% of the total heat radiation amount. The heat transferred to the updraft acts as heating and heating of the space, but impairs the effect of radiant heating of the front object to be heated, which is the original purpose. Here, by providing the projections 18 so as not to communicate with the surface of the heat receiving plate 8 vertically, an air layer stagnating between the projections 18 is formed to serve as an adiabatic zone, which acts to prevent convective heat transfer. It is effective that the height of the projection 18 is about 3 to 5 mm, and it is more effective that the tip area in contact with the ascending airflow is smaller. For example, a trapezoidal cross section is preferable. By doing so, heat dissipation due to convective heat transfer is reduced, and radiant heat can be supplied more effectively.

In the case of the embodiment shown in FIG.
Is omitted from the drawing. In the above, the present invention has been described with an example in which the present invention is applied to a combustion apparatus using gas fuel. However, it goes without saying that the present invention is not limited to this. That is, the present invention is also effective in the following cases.

As the fuel type, gas fuel supplied to a container such as butane gas or liquid fuel such as kerosene can be used. When a liquid fuel is used, a means for vaporizing the liquid fuel upstream of the mixture supply pipe 1 is added. The air may be supplied by a self-suction type utilizing the supply pressure of the fuel, or may be supplied by a forced supply using a fan or the like.

Although the ceramic honeycomb is used as the carrier of the catalyst body 3, the material and the shape are not limited as long as it has a large number of communication holes through which the premixed gas can flow. A sintered body, a metal honeycomb, a metal nonwoven fabric, a braided body of ceramic fibers, and the like can be used, and the shape is not limited to a flat plate, but a curved shape, a tubular shape, a corrugated shape, and the like.
Although it can be set arbitrarily according to the workability of the material and the application, it is preferable to use a ceramic material having low thermal conductivity in order to radiate most of the reaction heat to the upstream side. The active component is generally a noble metal such as platinum, palladium, or rhodium, but may be a mixture of these or other metals or oxides thereof, or a mixed composition thereof, It is possible to select an active ingredient according to species and use conditions.

Although the ignition means is not described in detail, the catalyst body 3 is directly preheated by an electric heater which has been generally used in the related art, or a flame port and an igniter are provided upstream of the catalyst body 3 so as to be initially used. At this point, when the catalyst body reaches a predetermined activation temperature by heating with the high-temperature exhaust gas, the fuel supply is temporarily stopped to extinguish the flame, and immediately thereafter, the fuel supply is restarted again to start the catalytic combustion reaction. Or a flame is formed downstream of the catalyst body 3, and the heat of combustion causes the formation of the catalyst body 3.
May be used to automatically shift to catalytic combustion, and none of these methods impair the effects of the present invention. As an igniter for starting flame combustion, it is also effective to use a battery type or a piezoelectric igniter.

[0025]

As described above, in the catalytic combustion apparatus according to the present invention, the radiation efficiency is maintained at a sufficiently high level, the minimum reaction temperature of the catalyst is secured, and it is possible to visually confirm the continuation of combustion. The radiation wavelength distribution can be converted into a state having a high ratio of far-infrared rays, and an economical and comfortable combustion device can be provided.

Further, by providing a heat exchange chamber which communicates with the downstream side of the combustion chamber and includes a radiator plate as a part of the component, the heat of the exhaust gas can be effectively converted to radiant heat.

Further, by forming a discontinuous uneven structure in the vertical direction on the outer surface of the heat radiating plate, heat dissipation due to convective heat transfer can be prevented, and the combustion device can convert the combustion heat more effectively into radiant heat. Can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional perspective view of a combustion device according to a first embodiment of the present invention.

FIG. 2 is a radiation characteristic diagram for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a sectional perspective view of a combustion device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air-fuel mixture supply pipe 2 Combustion chamber 3 Catalyst body 4 Exhaust tube 5 Heat exchange chamber 6 Heat exchange fin 7 Exhaust port 8 Heat sink 18 Projection

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Akira Maenishi 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-10-86934 (JP, A) JP-A-5-187618 (JP, A) JP-A-62-299610 (JP, A) JP-A-63-113802 (JP, A) U) WO 97/21957 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 14/18 F23C 11/00 306

Claims (3)

(57) [Claims] 1. A combustion chamber for supplying a mixture of fuel and air, a catalyst body having a plurality of communication holes installed in the combustion chamber, and a wall of the combustion chamber facing an upstream surface of the catalyst body. A radiator plate formed of a non-transmissive material of a heat ray, and an exhaust flow path opened on the downstream side of the catalyst body in the combustion chamber, and a radiator surface exposed to the outside of the radiator plate Is at least twice as large as the area of the upstream surface of the catalyst body facing the heat radiating plate. 2. The catalytic combustion device according to claim 1, further comprising a heat exchange chamber which communicates with an exhaust flow path opened to the combustion chamber and has the radiator plate as a component. . 3. The catalytic combustion device according to claim 1, wherein a discontinuous uneven structure is formed on an outer surface of the heat radiating plate in a vertical direction.