JPH07103966B2 - Catalytic combustor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wick vaporization type natural aeration type catalyst combustor for liquid fuel used for heating, heating, drying and the like.

2. Description of the Related Art So-called wick vaporization type combustors have been widely used. There is. In particular, a large number of systems (radiative combustors) in which a heat-transmitting body is provided on the upper side wall of the combustion cylinder and the combustion chamber wall facing the heat-transmitting body is red-heated to radiate heat therefrom are radiated. By the way, a conventional combustor of this type has a red heat section made of an upright metal porous plate and a heat transmissive body which is opposed to the red heat section, and both of them are arranged to face each other at equal intervals in the vertical direction.

Problems to be Solved by the Invention In the above conventional configuration, since the fuel gas and the air are sucked up by the natural ventilation force, the amount of air flowing in through the large opening of the red-heated portion is lower than that of the lower portion where the ventilation force is large. Therefore, the amount of combustion tends to concentrate in the lower part,
Even in the red hot state, the lower part became sufficiently hot, but the upper part was hard to red hot. Especially in the case where the red-heated part is composed of a honeycomb catalyst and a premixed gas of fuel and air is passed through the catalyst and catalytically burned on the surface, the above non-uniformity of the flow directly burns. This resulted in non-uniform density, and thus non-uniform red heat. Moreover, above the lower combustion density, the temperature did not rise sufficiently, so that the reaction activity could not be sufficiently maintained, which sometimes resulted in incomplete combustion.

In view of the above-mentioned conventional drawbacks, the present invention is to make the flow rate of the premixed gas passing through the oxidation catalyst layer uniform in the up-down direction, to make the red heat state uniform, and to enable complete combustion and high radiation efficiency. is there.

Means for Solving the Problems In the present invention, an oxidation having a large number of communication holes through a secondary air port is provided above a vaporization chamber in which a plurality of air holes are formed in a side wall with a tip of a wick facing the bottom. In a combustion cylinder having a catalyst layer and having a heat-transmitting body facing the front surface (upstream side) of the oxidation catalyst layer, the gap between the oxidation-catalyst layer and the heat-transmitting body is made smaller toward the upper part. is there.

Effect The present invention, by means of the above means, changes the gap between the oxidation catalyst layer and the heat transmissive body arranged in front of the oxidation catalyst layer when catalytically burning most of the fuel vaporized from the wick on the surface of the oxidation catalyst layer. The flow path resistance is changed in proportion to the natural ventilation force to make the surface combustion density of the oxidation catalyst layer uniform. By doing so, the surface temperature of the oxidation catalyst layer can be made uniform, incomplete combustion can be prevented, and large radiation heat release from the surface of the oxidation catalyst layer can be effectively utilized to provide a combustor with high radiation efficiency.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, 1 is a liquid fuel tank, 2 is a wick, 3 is a combustion cylinder, and the combustion cylinder 3 has the following configuration. A large number of air holes 4a are formed in the side wall of the vaporization chamber 4 whose lower part faces the tip of the wick 2, and a secondary air port 5 is opened above it. A large number of communication holes are provided above the secondary air port 5.
An oxidation catalyst layer 6 having 6a is provided upright, a glass window 7 is provided so as to face the front surface thereof, and an exhaust port 8 is provided at an upper portion of the rear surface. Here, the oxidation catalyst layer 6 is in the shape of an upright flat plate with the communication hole 6a being horizontal, but the glass window 7 facing it is provided so as to be inclined so that the upper side is closer to the oxidation catalyst layer 6, and the gap between the two is lower. Has a trapezoidal inclined space with a large cross section and a small upper section.

Next, the operation will be described in detail. The fuel vaporized from the wick 2 rises while being mixed with the air supplied from the air holes 4a in the vaporization chamber 4, but a part thereof forms a flame here, and the combustion heat thereof is It is supplied to the wick 2 and serves as heat of vaporization of the fuel.
The air-fuel mixture that has left the vaporization chamber 4 is supplied with a sufficient amount of air through the secondary air port 5 and rises as an air-excess air-fuel mixture, but since the oxidation catalyst layer 6 is provided above it. The catalyst burns mainly on the upstream side (front side), and flows to the downstream side (rear side) through the communication hole 6a. The combustion exhaust gas is discharged from an exhaust port 8 provided on the upper rear surface of the oxidation catalyst layer 6. On the other hand, the radiant heat released from the oxidation catalyst layer 6 heated by the combustion heat is supplied to the front surface through the glass window 7 provided opposite to the radiant heat.

By the way, the fuel gas vaporized from the wick 2, the air holes 4a, and the air supplied from the secondary air port 5 flow by the natural aeration force (draft) generated in the combustion cylinder 3, but when passing through the oxidation catalyst layer 6. In addition, the strength of the natural ventilation force is large in the downward direction and small in the upward direction, so that the amount of the air-fuel mixture passing therethrough is increased. However, here, the oxidation catalyst layer 6 and the glass window 7
The gap between and is large downward and small upward, and by narrowing the space slightly excessively with respect to the residual air-fuel mixture,
By gradually increasing the flow velocity, the dynamic pressure and the static pressure can be increased, and the vertical difference in the natural aeration force can be offset. Therefore, the amount of the air-fuel mixture passing per unit area can be made substantially constant, the combustion density on the surface of the oxidation catalyst layer 6 can be made substantially uniform, and the red heat temperature can be made uniform evenly in the vertical direction. Thus, stable complete combustion can be secured without causing incomplete combustion due to partial temperature shortage on the surface of the oxidation catalyst layer 6. Further, the fuel gas passing therethrough undergoes catalytic combustion on the surface of the oxidation catalyst layer 6, so that the combustion temperature becomes lower (500 to 800 ° C) than that of conventional flame combustion (about 1500 ° C or higher).
C.) and the generation of nitrogen oxides can be almost eliminated.
Further, since the catalytic combustion reaction proceeds on the surface of the oxidation catalyst layer 6 (mainly on the front surface), the combustion heat directly heats the catalyst layer 6, and since the combustion density is uniform, the temperature rises to a uniform temperature and Radiation is evenly distributed over the entire surface. Therefore, the radiation efficiency is significantly higher than conventional flame heating (25-30%),
The results have reached 40-45%. Also, since the red heat state is uniform, the combustion heat can be effectively radiated and radiated,
In addition, visually, it is safe and comfortable to heat and heat.

By the way, when the gap between the oxidation catalyst layer 6 and the glass window 7 is changed, the surface to be tilted may be the glass window 7 tilted as in this embodiment, or vice versa, as shown in FIG.
Even if the glass window 7 is set upright and the oxidation catalyst layer 6 is tilted, or even if both are tilted, the effect of uniform combustion can be exhibited. The communication hole 6a may be horizontal as shown in FIG. 1, but it is preferable that the communication hole 6a be an inclined hole facing upward toward the back surface in order to reduce the resistance in the flow direction, and as shown in FIG. It is effective to make the catalyst layer 6 inclined.

Although the glass window 7 and the oxidation catalyst layer 6 have a flat plate shape in the above-mentioned embodiment, they may be formed into a cylindrical shape together, and by doing so, the air-fuel mixture, the flame, and the exhaust gas in the lateral direction can be formed. Partial bias is eliminated and uniform, complete and stable combustion is maintained over the entire circumference. Further, although the flame and the exhaust gas have the property of being concentrated in the center, when the oxidation catalyst layer 6 is formed into a cylindrical shape, the air-fuel mixture forms a flow path from the outer periphery to the center. It becomes a forward flow, and the flow path resistance is reduced. Therefore, although the resistance of the communication hole 6a of the oxidation catalyst layer 6 is relatively large, a sufficient amount of ventilation force (draft) is generated, and the predetermined air and fuel are supplied without extending the height of the exhaust port 8. It can be carried out. It is most appropriate to form the oxidation catalyst layer 6 into a cylindrical shape together with the glass window 7 in order to obtain the uniformity of the entire circumference, but a horizontal cross section of porous flat plates arranged in a triangle, a quadrangle, a hexagon, or an octagon. A polygonal tubular shape such as a polygonal shape may be used, and it is possible to solve the problems in cylindrical processing and to sufficiently exhibit the above effect in terms of performance. Furthermore, by making the catalyst layer a cylinder or a polygonal cylinder, the uniformity and stability of the combustion state in the lateral direction can be secured, and sufficient ventilation can be obtained without the need for a large combustion cylinder height. It can heat and heat with high radiation.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to eliminate the deviation in the vertical direction of the flow of the premixed gas, and to make the combustion uniform and the red heat temperature uniform, without incomplete combustion and nitrogen oxidation. It is possible to provide a catalytic combustor capable of producing a clean exhaust gas with extremely few substances and capable of highly efficient radiation heat dissipation.

[Brief description of drawings]

FIG. 1 is a sectional view of a catalytic combustor according to one embodiment of the present invention, and FIG. 2 is a sectional view of a catalytic combustor according to another embodiment. 2 ... wick, 3 ... combustion cylinder, 4 ... vaporization chamber, 5 ... secondary air port, 6 ... oxidation catalyst layer, 7 ... glass window, 8 ... exhaust port.

Claims (3)

[Claims] 1. A vaporization chamber having a lower end facing a vertically moving wick and a plurality of air holes formed in a side wall, a secondary air port provided near an upper end of the vaporization chamber, and the secondary air. An oxidation catalyst layer having a large number of communication holes erected above the mouth, and a heat transmission body disposed so as to face the upstream side surface of the oxidation catalyst layer,
An exhaust port provided on the downstream upper side of the catalyst layer,
A catalyst combustor in which the gap between the oxidation catalyst layer and the heat-transmitting body is reduced toward the upper side. 2. The catalytic combustor according to claim 1, wherein the oxidation catalyst layer is upright and the heat transmission body is inclined. 3. The catalytic combustor according to claim 1, wherein the heat transmission body is upright and the oxidation catalyst layer is inclined.