JPH09280517A - Catalytic combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the recondensation of liquid fuel and the generation of tar and constantly ensure a combustion stability by providing a heat ray transmitting member for transmitting heat ray spaced by a prescribed distance from a heat receiving surface in the catalyst member side of a radiation heat receiving member. SOLUTION: A catalyst member 1 and an auxiliary catalyst member 6 employ a cordierite honeycomb having a permeability as a carrier and carry a noble metal catalyst such as palladium, platinum or the like. The auxiliary catalyst member 6 is provided in the downstream side of the catalyst member 1. An electric heater 4 is provided between the catalyst member 1 and the auxiliary catalyst member 6. A radiation heat receiving member 9 is provided in the upstream side of and opposed to the catalyst member 1 so as to easily receive radiation. The radiation heat receiving member 9 is provided with a heat exchanging part 10. A heat ray transmitting member 11 is formed with glass and formed in the catalyst member 1 side of the radiation heat receiving member 9 through a space 11a. A mixed gas supply passage 13, an air supply passage 14, a fuel supply passage 15 and a vaporizing part 16 for liquid fuel are provided in the upstream side of the radiation heat receiving member 9. An exhaust gas heat exchanging part 17 and an exhaust passage 18 are provided in the downstream side of the auxiliary catalyst member 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to home use,
Alternatively, the present invention relates to a catalytic combustion device applied to hot water supply and heating for business use.

[0002]

2. Description of the Related Art A catalytic body in which a noble metal catalyst such as platinum or palladium is carried on a carrier such as cordierite is catalytically burned, and a heat exchanger is provided to transfer the combustion heat to a fluid to be heated such as water to supply hot water. A catalytic combustion device applied to heating has been proposed. Nitrogen oxides (hereinafter referred to as NO
(x) is hardly generated, and lean combustion is possible and combustion stability is excellent. At the start of catalytic combustion, the preheating burner burns the mixed gas of fuel gas and air in a flame to heat the catalyst to the activation temperature or higher, and then the supply of the mixture is stopped to extinguish the flame of the preheating burner. , Again, supplying the air-fuel mixture for catalytic combustion, or, as another method, without heating the flame, raise the temperature of the catalyst body with an electric heater or the like, and then pass the air-fuel mixture through the catalyst body to carry out the catalytic combustion. Was there. Further, in order to enhance hot water supply and heating ability, a method of increasing the temperature of the catalyst body or increasing the red heat area of the catalyst body within a range where deterioration of the catalyst can be suppressed has been applied.

[0003]

However, the conventional catalytic combustion apparatus has the following problems. First, catalytic combustion has a great advantage of not generating NOx, but since the combustion temperature is low, if the amount of heat exchange with the fluid to be heated is increased, the catalyst body becomes large and it is difficult to downsize the entire device. And after vaporization in the case of liquid fuel,
It was easy for fuel to re-condense and generate tar. Also, after burning the flame with a preheating burner at the start of catalytic combustion,
Stop the supply of air-fuel mixture to extinguish the flame of the preheating burner,
Again, the method of supplying the air-fuel mixture to carry out catalytic combustion tends to be complicated in control, and if the temperature of the catalytic body is raised by an electric heater or the like without flame combustion, there is a problem that the startup time becomes long. It was Also, when trying to increase the size of the catalyst body or increase the amount of heat exchange with the fluid to be heated,
In particular, combustion stability became insufficient in the low combustion amount region, and it was difficult to expand the combustion amount variable range (hereinafter, referred to as TDR).

In consideration of such problems of the conventional catalytic combustion apparatus, the present invention can suppress recondensation of liquid fuel and tar generation while maintaining the radiative heat transfer characteristic to the radiant heat receiver. Another object of the present invention is to provide a catalytic combustion apparatus that can ensure combustion stability even if the amount of heat exchanged with the fluid to be heated is increased without inhibiting the combustion reaction on the upstream surface of the catalyst body. To do.

[0005]

In order to solve the above problems, the present invention provides, as a first means, a gas permeable catalyst body, and a radiant heat receiver having a heat receiving surface facing the upstream surface of the catalyst body. A catalytic combustion apparatus having a heat exchange section provided on a radiant heat receiving body, a vaporization section for liquid fuel to be sent to a catalyst body, and a heat ray transmitting body located on the catalyst body side of the radiant heat receiving body via a heat receiving surface and a space. .

As a second means, a gas permeable catalyst body, a radiation heat receiving body having a heat receiving surface facing the upstream surface of the catalyst body, a vaporization part of liquid fuel to be sent to the catalyst body, and heat receiving of the radiation heat receiving body The catalytic combustion device is provided with a heat exchange section located on the back side of the surface through a thermal resistor.

As a third means, a gas permeable catalyst body, a radiation heat receiving body having a heat receiving surface facing the upstream surface of the catalyst body, a heat exchange section provided in the radiation heat receiving body, and a downstream side of the catalyst body. The auxiliary catalyst body located in, and an electric heater located between the catalyst body and the auxiliary catalyst body, the electric heater is energized at the start of combustion, after heating the catalyst body and the auxiliary catalyst body,
The catalyst heater is a catalyst combustion device that stops the energization of the electric heater and, after a predetermined time, supplies an air-fuel mixture to burn the catalyst.

As a fourth means, a gas permeable catalyst body, a radiation heat receiving body having a heat receiving surface facing the upstream surface of the catalyst body, a heat exchange section provided in the radiation heat receiving body, and a downstream side of the catalyst body. The auxiliary catalyst body located at and the ignition means located between the catalyst body and the auxiliary catalyst body are provided.At the start of combustion, the air-fuel mixture is supplied almost at the same time as the operation of the ignition means, and a flame is generated on the downstream surface of the catalyst body. It is a catalytic combustion device that adheres and shifts from flame combustion to catalytic combustion.

As a fifth means, the heat exchange section near the radiation heat receiving body and the exhaust gas heat exchange section on the downstream side of the catalyst body are independent of each other,
A catalyst combustion apparatus is provided in which the fluid to be heated in the heat exchange section and the fluid to be heated in the exhaust gas heat exchange section are different fluids.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of the first embodiment. The main parts of the catalytic combustion apparatus of Embodiment 1 are the catalyst body 1, the catalyst body support 2, the combustion chamber wall 3, the electric heater 4, the electric heater support 5, the auxiliary catalyst body 6, the auxiliary catalyst body support 7, the auxiliary combustion chamber wall. 8, a radiation heat receiving body 9, a heat exchange unit 10, a heat ray transmitting body 11, and a heat ray transmitting body support 12. The catalyst body 1 and the auxiliary catalyst body 6 use a cordierite honeycomb having air permeability as a carrier and carry a noble metal catalyst such as palladium or platinum. The auxiliary catalyst body 6 is provided on the downstream side of the catalyst body 1, and the electric heater 4 is located between the catalyst body 1 and the auxiliary catalyst body 6. The radiation heat receiving body 9 is provided on the upstream side of the catalyst body 1 so as to face the catalyst body 1 so as to easily receive radiation.
A heat exchange section 10 is installed on the radiant heat receiver 9. The heat ray transmissive body 11 is made of glass, and is provided on the catalytic body side of the radiation heat receiving body 9 via the space 11a. An air-fuel mixture supply path 13, an air supply path 14, a fuel supply path 15, and a liquid fuel vaporization section 16 are provided on the upstream side of the radiant heat receiver 9. On the other hand, on the downstream side of the auxiliary catalyst body 6, the exhaust gas heat exchange section 17,
An exhaust passage 18 is provided.

Next, the operation of this embodiment will be described. First, at the start of combustion, the electric heater 4 is energized to heat the catalyst body 1 or the auxiliary catalyst body 6 to an activation temperature or higher, and then the energization to the electric heater 4 is stopped, and the surface temperature of the electric heater 4 is set to the ignition temperature. Then, the air-fuel mixture is supplied to the catalytic body 1 and catalytically burned. The air-fuel mixture is a mixture of the fuel vaporized through the fuel supply passage 15 and the liquid fuel vaporization portion 16 and the air from the air supply passage 14,
Mixing is promoted in the mixture supply path 13. During catalyst combustion, the upstream surface of the catalyst body 1 is red-heated and radiant energy is emitted to the upstream side. This radiant energy is absorbed by the radiant heat receiving body 9 and converted into heat energy again, so that it is radiatively transferred from the catalyst body 1 to the radiant heat receiving body 9, and thereafter, by heat conduction, to the radiant heat receiving body 9. The heat exchange section 10 provided
The heat is transferred to the fluid to be heated. Unlike convective heat transfer, radiative heat transfer is performed without disturbing the flow of the air-fuel mixture, so that the combustion reaction on the upstream surface of the catalyst body 1 is not hindered,
Combustion stability can be ensured even if the amount of heat exchange with the heated fluid is increased.

When the heat transfer performance is enhanced, the radiation heat receiving body 9
However, it is considered that the liquid fuel such as kerosene is made to flow in in a vaporized state. At that time, in order to prevent the liquid fuel from re-condensing on the catalyst side wall surface (heat receiving surface) of the radiant heat receiver 9 and tar from being easily generated, the heat ray transmitting body 11 is provided on the catalyst side of the radiant heat receiver 9 in the space 11a It is provided through. As a result, the heat ray transmitting member 11 is maintained in a state where the radiation heat transfer characteristic to the radiation heat receiving member 9 is maintained.
The temperature of the side wall surface of the catalyst is increased to suppress recondensation of liquid fuel and tar generation. The space 11a acts as an air insulation layer. The combustion gas that has passed through the catalyst body 1 is purified by the auxiliary catalyst body 6, the exhaust heat is recovered by the exhaust gas heat exchange section 17, and then the exhaust gas is discharged through the exhaust passage 18.

Further, the space 11a between the heat receiving surface of the radiation heat receiving body 9 and the heat ray transmitting body 11 is pressurized by a fan or the like for blowing combustion air to prevent the mixture from flowing into the space 11a. However, recondensation of liquid fuel and tar generation in the space 11a can be suppressed.

As described above, the electric heater 4 is provided between the catalyst body 1 and the auxiliary catalyst body 6, and the electric heater 4 is provided at the start of combustion.
To heat the catalyst body 1 or the auxiliary catalyst body 6 and then stop the power supply to the electric heater 4, and after a predetermined time, supply an air-fuel mixture to burn the catalyst so that the electric heater 4 near the electric heater 4 is heated. Catalytic body 1 without abnormal ignition or generation of NOx
A zone between and and the auxiliary catalyst body 6 is kept warm to shorten the start-up time. Further, since the upstream temperature of the catalyst body 1 does not rise during startup, heat does not move to the radiation heat receiving body 9 and the heat of the electric heater 4 can be efficiently used for startup. In particular, by stopping the flow of the fluid to be heated in the heat exchange section 10 at the time of startup, heat transfer to the radiant heat receiver 9 can be suppressed, so that the startup time can be further shortened. During catalyst combustion, the auxiliary catalyst body 6 improves exhaust gas purification performance, raises the temperature of the catalyst body 1, and enhances radiant heat transfer performance to the radiant heat receiver 9.

On the other hand, at the start of combustion, it is also possible to supply the air-fuel mixture almost at the same time as energizing the electric heater 4 to cause a flame to adhere to the downstream surface of the catalyst body 1 and to shift from flame combustion to catalyst combustion. In this case, the catalyst body 1 by the electric heater 4
Since no preheating is required, the rise time to catalytic combustion can be remarkably shortened, and since it is not necessary to add a preheating burner, the structure and control can be simplified. At this time, the electric heater 4 is merely used as one of the ignition means, and other ignition means such as piezoelectric ignition may be used.

By providing the exhaust gas heat exchange section 17 on the downstream side of the catalyst body 1, the heat efficiency can be improved. In particular, the heat exchange section 10 near the radiation heat receiving body 9 and the catalyst body 1 are provided.
The exhaust gas heat exchange section 17 on the downstream side of the
The fluid to be heated in 0 and the fluid to be heated in the exhaust gas heat exchange section 17 are different fluids (for example, the fluid to be heated in the heat exchange section 10 is a refrigerant, and the fluid to be heated in the exhaust gas heat exchange section 17 is By using water as the water), the adaptability as a heat exchanger can be expanded, heat transfer performance and combustion stability can be easily achieved at the same time, and high TDR can be achieved.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 2 is a sectional view of the second embodiment. The catalytic combustion device according to the second embodiment does not have the heat ray transmitting body 11 according to the first embodiment, and the radiation heat receiving body 9 and the heat exchanging unit 1 are not provided.
The thermal resistor 19 is provided between 0. The thermal resistor 19 suppresses heat conduction and does not need to be limited in shape.

In the second embodiment, the temperature of the side wall surface of the catalyst body of the radiant heat receiver 9 is set to a temperature (about 240 ° C. or higher) at which liquid fuel does not recondense or tar, and to maintain the heat exchange amount,
The heat transfer area of the heat exchange section 10 is increased so as not to increase the size of the entire device. Compared to the first embodiment, the radiant heat transfer performance from the catalytic body 1 to the radiant heat receiving body 9 is reduced, but it is not necessary to install the heat ray transmissive body 11 (glass), and the cost can be easily reduced.

[0019]

As described above, according to the catalytic combustion device of the present invention, the following effects can be obtained.

By providing a heat ray transmitting body on the catalyst side of the radiant heat receiver via the heat receiving surface and a space, recondensation of liquid fuel and tar generation are suppressed while maintaining radiative heat transfer characteristics to the radiant heat receiver. be able to. Unlike convection heat transfer,
Radiant heat transfer without disturbing the flow of the air-fuel mixture does not hinder the combustion reaction on the upstream surface of the catalyst body,
Combustion stability can be ensured even if the amount of heat exchange with the fluid to be heated is increased.

Further, an electric heater is provided between the catalyst body and the auxiliary catalyst body, and the electric heater is energized at the start of combustion to heat the catalyst body or the auxiliary catalyst body. After a lapse of time, by supplying the air-fuel mixture to carry out catalytic combustion, abnormal ignition or N
There is no generation of Ox, and the space between the catalyst body and the auxiliary catalyst body is set as a heat retaining region, and the startup time can be shortened.

Further, a flame is attached to the downstream surface of the catalyst body,
By switching from flame combustion to catalytic combustion, preheating of the catalyst body is not required, the rise time to catalytic combustion can be significantly shortened, and there is no need to add a preheating burner. It can be simplified.

Further, the heat exchange section in the vicinity of the radiation heat receiving body and the exhaust gas heat exchange section on the downstream side of the catalyst body are made independent, and the fluid to be heated in the heat exchange section and the fluid to be heated in the exhaust gas heat exchange section are different fluids. By doing so, the adaptability as a heat exchanger can be expanded, heat transfer performance and combustion stability can be easily made compatible, and high TDR can also be achieved.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a catalytic combustion device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 catalyst body 4 electric heater 6 auxiliary catalyst body 9 radiant heat receiver 10 heat exchange part 11 heat ray transmissive body 16 liquid fuel vaporization part 17 exhaust gas heat exchange part 19 thermal resistor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Maenishi 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A permeable catalyst body, a radiation heat receiving body located upstream of the catalyst body and having a heat receiving surface facing the catalyst body, and a heat exchange section provided in the radiation heat receiving body. A vaporizing section for liquid fuel to be sent to the catalyst body, and a heat ray transmitting body disposed on the catalyst side of the radiation heat receiving body at a predetermined distance from the heat receiving surface and transmitting heat rays. Catalytic combustion device. 2. The catalytic combustion device according to claim 1, wherein the space between the heat receiving surface of the radiation heat receiving body and the heat ray transmitting body is pressurized. 3. A gas-permeable catalyst body, a radiation heat-receiving body located upstream of the catalyst body and having a heat-receiving surface facing the catalyst body, and a vaporization section for liquid fuel sent to the catalyst body,
A catalytic combustion device, comprising: a heat exchange section provided on the back surface of the heat receiving surface of the radiation heat receiving body via a heat resistor. 4. A catalyst body having gas permeability, a radiation heat receiving body located upstream of the catalyst body and having a heat receiving surface facing the catalyst body, and a heat exchange section provided in the radiation heat receiving body. , An auxiliary catalyst body arranged on the downstream side of the catalyst body, and an electric heater arranged between the catalyst body and the auxiliary catalyst body, and energizing the electric heater at the start of combustion,
After heating the catalyst body and the auxiliary catalyst body, stopping the energization of the electric heater, and after a predetermined period of time, supplying a mixture gas for catalytic combustion. 5. A catalyst body having air permeability, a radiation heat receiving body located on the upstream side of the catalyst body and having a heat receiving surface facing the catalyst body, and a heat exchange section provided in the radiation heat receiving body. , An auxiliary catalyst body arranged on the downstream side of the catalyst body, and an ignition means arranged between the catalyst body and the auxiliary catalyst body. A catalyst combustion apparatus, characterized in that the catalyst is supplied and a flame is attached to the downstream surface of the catalyst body to shift from flame combustion to catalyst combustion. 6. The catalytic combustion apparatus according to claim 1, 3, 4 or 5, wherein an exhaust gas heat exchange section is provided on the downstream side of the catalyst body. 7. A heat exchange section in the vicinity of the radiant heat receiving body and an exhaust gas heat exchange section on the downstream side of the catalyst body are independent systems, and a fluid to be heated in the heat exchange section and a heated body in the exhaust gas heat exchange section are heated. The catalytic combustion device according to claim 6, wherein the fluids are different fluids.