JPH09210316A - Catalytic combustion heater - Google Patents

Abstract

(57) [Abstract] [Problem] To supply sufficient heat to air to be heated,
Providing a catalytic combustion heater that prevents an increase in HC emissions and improves exhaust emissions. SOLUTION During steady combustion, air supplied to an intake pipe 18 is guided by an air flow guide 21 from an air flow passage 16 and moves upward along the outer periphery of half of a combustion cylinder 12. Then, the air in the air flow passage 16 is heated by the heat of the combustion cylinder 12 receiving the radiant heat from the catalyst layer 13, passes over the air flow guide 21 and moves downward in the air flow passage 16 on the opposite side. It is supplied from the port 20 into the fuel vaporizer 6. In the fuel vaporizer 6, the vaporized fuel and heated air are mixed, and the air-fuel mixture passes through the combustion cylinder 12 and is burned in the catalyst layer 13 to become combustion gas, which is heat-exchanged with the water in the circulating water passage 8. The air in the air flow passage 16 comes into contact with the entire outer circumference of the combustion cylinder 12, so that sufficient heat is supplied and clean combustion is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion type heater, and more particularly to a catalytic combustion type heater which prevents exhaust gas combustion and improves exhaust emission.

[0002]

2. Description of the Related Art Generally, a catalytic combustion type heater is a type that heats water supplied to a radiator inside a vehicle interior directly or by burning a portion of engine fuel catalytically with a burner. It is used as an auxiliary heater until the water temperature rises sufficiently. In such a burner of a catalytic combustion type heater, the supplied fuel is vaporized and mixed with combustion air, and this mixture is supplied to a catalyst-carrying combustor for reaction and catalytic combustion.

As shown in FIG. 6, in the conventional catalytic combustion type heater, the burner is mainly composed of a fuel vaporizer 50 which mixes fuel and combustion air to vaporize the fuel, and constituent members of the fuel vaporizer 50. Combustion cylinder 51 and the combustion cylinder 5
1 and the catalyst layer 52 held inside. The fuel vaporizer 50 is covered by a housing 53,
An electric heater 55 is provided in the wall of the fuel vaporizer 50, and an end of a fuel introduction pipe 56 is opened in the space of the fuel vaporizer 50. The electric heater 55 and the fuel introduction pipe 56 are fixed to the housing 53. Further, inside the housing 53, a combustion gas passage 57 through which a part of the combustion gas passes is formed on the outer peripheral portion of the combustion cylinder 51, and communicates with an exhaust pipe 72 fixed inside the wall of the housing 53. Further, the housing 53 is provided with a first air introduction port 60 and an air flow passage 61, and the first air introduction port 60 and the air flow passage 61 are provided in the fuel carburetor 50. Of the air inlet 62. Also,
The air flow passage 61 is provided on the outer peripheral portion of the combustion gas flow passage 57, and heat is exchanged at this portion to preheat the combustion air. Further, the combustion cylinder 51 is a housing 6 of a half container.
3, and a combustion gas outlet 65 is provided in the upper portion of the housing 63.

The fuel passes through a fuel introducing pipe 56 by a fuel pump 67 connected to a fuel tank 66, and a fuel vaporizer 5
It is supplied in the space of 0. On the other hand, the combustion air is supplied from the air pump 68 through the first air introduction port 60 and the air flow path 61 to the second air introduction port 62 into the space of the fuel vaporizer 50. Then, in the fuel vaporizer 50, the fuel and the combustion air are mixed and the fuel is vaporized, and the mixture is supplied to the catalyst layer 52 in the combustion cylinder 51 to start catalytic combustion. A part of the combustion gas heated by the catalytic combustion is discharged from the combustion gas outlet port 65, and the rest passes through the space of the housing 63 and passes through the exhaust port 71 provided in the partition plate 70 to the inside of the housing 53. The exhaust gas passes through the combustion gas passage 57 and is exhausted from the exhaust pipe 72 fixed to the housing 53. Then, when the combustion gas passes through the combustion gas passage 57, heat is exchanged between the combustion gas and the combustion air in the air passage 61 at the outer peripheral portion of the combustion gas to preheat the combustion air. By preheating the combustion air in the air flow path 61 with the combustion gas in this manner, it is possible to prevent the temperature of the catalyst layer 53 from becoming lower than its activation temperature, so that clean combustion is continued.

Such a catalytic combustion type heater is also described in, for example, Japanese Patent Laid-Open No. 1-306709. The technique described in this publication effectively heats the combustion gas in the exhaust passage to heat the premixing chamber to promote vaporization of the fuel and to exchange heat between the combustion air and the combustion gas. By preheating the combustion air, the oxidation ability on the catalyst body is increased to improve the combustion performance.

[0006]

In each of the above-mentioned prior arts, the aim is to preheat the combustion air by exchanging heat between the combustion gas and the combustion air. However, since the heat exchange between the gases is inefficient, the combustion air In order to supply a sufficient amount of heat to the heater, a large heat transfer surface is required, which inevitably increases the size of the heater itself. Further, if the heat transfer area is small, sufficient heat cannot be supplied to the combustion air, which makes clean combustion impossible.

The present invention was created in view of the above problems, and an object thereof is to supply sufficient heat to the air to be heated to prevent an increase in the amount of HC discharged. It is an object of the present invention to provide a catalytic combustion heater with improved exhaust emission.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the means described in claim 1 can be adopted. According to this means, during the steady combustion of the catalytic combustion type heater, the air to be heated is supplied to the entire outer peripheral portion of the combustion cylinder in the air flow passage. Then, the air is heated in the air flow passage by exchanging heat with the heat of the combustion cylinder that is directly receiving radiant heat from the catalyst layer, and is supplied into the fuel vaporizer. On the other hand, the fuel supplied to the fuel vaporizer is vaporized and mixed with the above-mentioned heated air, and the mixture reaches the catalyst layer fixedly installed in the combustion cylinder and undergoes catalytic combustion to become combustion gas, which causes heat exchange in the housing. The medium air is directly heated. As described above, according to the present invention, the heat is exchanged between the radiant heat of the solid combustion cylinder and the air, which is the gas in the air passage, so that the heat exchange efficiency is good. Moreover, since the air in the air flow path can contact the entire outer peripheral portion of the combustion cylinder, heat exchange efficiency can be increased, and therefore sufficient heat can be supplied to the air to be heated. As a result, clean combustion is possible and exhaust emission can be improved. By adopting the means of claim 2, the air in the air flow passage can surely come into contact with the entire outer peripheral surface of the combustion cylinder.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION First of the catalytic combustion type heater of the present invention
An embodiment will be described based on FIGS. 1 to 3. The upper housing 1 and the lower housing 2 are a pair of upper and lower half-container bodies, and are abutted and fixed to each other with an annular partition plate 3 sandwiched between their opening edges. An exhaust port 4 is formed in the lower housing 2, and a heater, for example, an electric heater 5 is provided in the wall of the housing 2, and a fuel vaporization of a semi-container which is held inside the lower housing 2 and is slightly small. A fuel introduction pipe 7 that communicates with the space of the container 6 is provided. The electric heater 5 is embedded under the fuel vaporizer 6. A circulating water passage 8 is formed in the wall of the upper housing 1, and a water inlet 10 and a water outlet 11 are provided on the wall surface as heat transfer media.
Is provided.

Inside the upper and lower housings 1 and 2, a cylindrical combustion cylinder 12 is embedded so that one end thereof surrounds the fuel vaporizer 7. The catalyst layer 13 in which the catalyst is supported on the honeycomb ceramic is fixed inside the combustion tube 12. A cylinder 15 is arranged on the entire outer circumference of the fuel vaporizer 6 and the combustion cylinder 12, and the fuel vaporizer 6 or the combustion cylinder 12 is disposed.
A long annular airflow passage 16 is formed between the entire outer circumference and the cylinder 15 surrounding the entire circumference, and the upper end of the airflow passage 16 is closed by a donut-shaped plate 17. Further, an intake pipe 18 communicating with the air flow passage 16 and supplied with air from a pump 22 is fixed to the lower housing 2, while the fuel vaporizer 6 is supplied with preheated air from the air flow passage 16 as fuel. An intake port 20 is provided for feeding the inside of the carburetor 6.

In the present invention, during steady combustion, heat is exchanged between the heat of the combustion cylinder 12 receiving the radiant heat from the catalyst layer 13 and the air in the air flow passage 16 to efficiently preheat the air. In order to obtain heated air, the air flow passage 16 is formed so as to surround the entire outer circumference of the combustion cylinder 12.
This is a combustion cylinder 1 that is a solid rather than heat exchange between gases.
This is because the heat exchange between 2 and air, which is the gas in the air flow passage 16, is more efficient.

The burner used in the present invention is a fuel vaporizer 6 which mixes fuel and heated air to vaporize the fuel.
A heater embedded in the bottom of the fuel vaporizer 6, for example, an electric heater 5, a combustion tube 12 extending from the fuel vaporizer 6, and a catalyst layer 13 fixed inside the combustion tube 12. Consists of.

Further, according to the present invention, as shown in FIG. 2, a pair of plate-shaped air flow guides 2 are provided in the air flow passage 16 so that the air to be preheated passes through the entire outer peripheral portion of the combustion cylinder 12.
1 is installed in the axial direction. Therefore, as shown in FIG. 3, the air to be preheated is supplied from the intake pipe 18, first rises in the air flow passage 16 by the air flow guide 21 as indicated by the arrow, and the radiant heat is emitted from the combustion cylinder 12. While moving over the upper end of the air flow guide 21, it moves to the air flow passage 16 on the opposite side, and this time it moves along the combustion cylinder 12 while changing its direction downward, and from the intake port 20 to the fuel carburetor. We will move into 6.

On the other hand, fuel is supplied from the fuel tank 23 to the fuel introduction pipe 7 by the fuel pump 25, and the electric heater 5
Is vaporized by the fuel vaporizer 6 heated by. And
The heated air supplied into the fuel vaporizer 6 from the air flow passage 6 through the intake port 20 is mixed with the vaporized fuel in the space of the fuel vaporizer 16. This mixed air-fuel mixture is the combustion cylinder 1
It reaches the catalyst layer 13 through the inside of 2, and undergoes catalytic combustion to become combustion gas. At this time, the radiant heat of the combustion cylinder 12 that is heated causes the air in the air flow passage 16 to become heated air.
The combustion gas exchanges heat with water, which is a heat exchange medium in the circulating water passage 8 in the space in the upper housing 1, and is exhausted from the exhaust port 4 through the passage 26 formed in the partition plate 3. It has become so.

Next, the operation of the first embodiment of the present invention will be described. During steady combustion of the catalytic combustion type heater, the air supplied to the intake pipe 18 by the air pump 22 flows from below the air flow passage 16 formed of a long annular cylinder to the air flow guide 21.
And is moved upward along the outer periphery of approximately half of the combustion cylinder 12. Then, the air flows in the air flow passage 16,
The airflow guide 21 exchanges heat with the heat of the combustion cylinder 12 which receives radiant heat directly from the catalyst layer 13 and becomes heated air.
Over the upper end of the and moves to the air flow passage 16 on the opposite side. The heated air is guided by the air flow guide 21 from above the air flow passage 16 on the opposite side, and moves downward along the outer circumference of the remaining approximately half of the combustion cylinder 12. Then, the heated air receives the heat of the combustion cylinder 12 that is directly receiving the radiant heat from the catalyst layer 13 in the air flow passage 16 and maintains the heating temperature, and from the intake port 20 into the space of the fuel carburetor 6. Supplied.

On the other hand, fuel is supplied from the fuel tank 23 to the fuel introduction pipe 7 by the fuel pump 25, and the electric heater 5
Is vaporized by the fuel vaporizer 6 heated by. And
The heated air and the vaporized fuel are mixed in the space of the fuel vaporizer 6, and the mixture passes through the inside of the combustion cylinder 12 to reach the catalyst layer 13 and is catalytically combusted to become combustion gas. At this time, as described above, the radiant heat of the combustion cylinder 12 which is heated causes the air in the air flow passage 16 to become heated air. The combustion gas exchanges heat with water, which is a heat exchange medium in the circulating water passage 8 in the space in the upper housing 1, and then passes through the passage 26 formed in the partition plate 3 to reach from the exhaust port 4. Exhausted.

As described above, the present invention does not perform heat exchange between gases, but rather between the radiant heat of the combustion cylinder 12 which is a solid and the air which is a gas in the air flow passage 16, that is, between the solid and the gas. Since the heat exchange is performed in, the heat exchange efficiency is good. Therefore, a complicated structure such as a heat exchange fin is not necessary. Further, since the air flow passage 16 is formed over the entire outer circumference of the combustion cylinder 12, the air to be heated in the air flow passage 16 can come into contact with the entire outer circumference of the combustion cylinder 12, so that the efficiency is improved. Can perform good heat exchange. Furthermore, since the plate-shaped airflow guide 21 is installed in the airflow passage 16,
The air to be heated can be supplied to the entire outer peripheral surface of the combustion cylinder 12. In this way, sufficient heat can be supplied to the air to be heated, and clean combustion becomes possible.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, water is used as the heat exchange medium, but in the present embodiment, air is directly heated. Therefore, the present embodiment has a configuration in which the circulating water passage 8 of the upper housing 1 in the first embodiment is deleted, and instead, the upper housing 1
An outlet 27 for the combustion gas heated by catalytic combustion is formed on the upper end surface of the. Then, the same reference numerals are given to the structural parts common to the above-described first embodiment, and the duplicated description will be omitted.

Since the present embodiment is configured as described above, between the combustion cylinder 12 that receives direct radiant heat from the ceramic supporting the catalyst during steady combustion and the air in the air flow passage 16 to be heated, Since efficient heat exchange is performed and sufficient heat is supplied to the air to be heated, clean combustion with less hydrocarbon generation is possible.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a catalytic combustion heater according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory diagram of an air flow in the first embodiment of the present invention.

FIG. 4 is an overall sectional view of a catalytic combustion heater according to a second embodiment of the present invention.

5 is a cross-sectional view taken along the line BB of FIG.

FIG. 6 is an overall sectional view of a conventional catalytic combustion heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Upper housing 2 ... Lower housing 5 ... (Electrical) heater 6 ... Fuel vaporizer 8 ... Circulating water passage 12 ... Combustion cylinder 13 ... Catalyst layer 15 ... Cylinder 16 ... Air flow passage 21 ... Air flow guide

Claims (3)

[Claims] 1. A burner for burning a supplied fluid is provided in a housing for heating air as a heat exchange medium,
The burner is a fuel vaporizer that mixes fuel and heated air to vaporize the fuel, a heater embedded in the bottom of the fuel vaporizer, and a combustion tube extending from the fuel vaporizer. A catalytic combustion type heater comprising a catalyst layer fixedly provided inside the combustion cylinder, characterized in that an air flow passage through which air to be heated circulates is arranged over the entire outer peripheral portion of the combustion cylinder. Catalytic combustion type heater. 2. A pair of airflow guides are axially provided in the airflow passage so that the air to be heated is supplied to the entire outer peripheral portion of the combustion cylinder. The described catalytic combustion heater. 3. The heat exchange medium is water, and a circulating water passage for circulating water, which is a heat exchange medium, is formed in the housing.
The described catalytic combustion heater.