JP2000146298A - Catalyst combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quicken rising of combustion while preventing discharge of CO or HC by preheating a catalyst efficiently. SOLUTION: Fins 3 bonded with a channel 4 for passing a fluid to be heated, i.e., water, are disposed in a combustion chamber 2 being supplied with a mixture gas of fuel gas and air along with a first planar catalyst 5 disposed in the vicinity of the fins 3 substantially in parallel therewith while spaced apart therefrom. The first catalyst 5 has a highly heat resistant thin metal plate as a basic material and jointed by brazing to a heater 6 at a part projecting to the downstream side of flow direction through the fins 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion apparatus for catalytically combusting an air-fuel mixture of fuel and air and utilizing the combustion heat for heating, heating, hot water supply, drying and the like.

[0002]

2. Description of the Related Art A conventional catalytic combustor is disclosed in Japanese Patent Application No. 08-23 / 1990.
As disclosed in Japanese Patent Application Laid-Open No. 5552 (JP-A-10-08506), the second catalyst body is preheated by a heater to cause catalytic combustion, and the temperature of the first catalyst body is raised by utilizing radiant heat from the second catalyst body. 2. Description of the Related Art A catalytic combustion apparatus of a type in which combustion is started by burning and heat generated is exchanged with a fluid to be heated is known.

[0003]

When the catalyst is preheated by using a heater as in the prior art, a heater is installed in a place close to the catalyst to raise the temperature of the catalyst. . In this case, a large amount of radiation from the surface of the red-heated heater and convective heat transfer by the high-temperature ambient air heat the catalyst indirectly and raise the temperature, but part of the radiation and high-temperature air is used to heat the catalyst. The heat was radiated outside the combustor without being used. Therefore, there has been a problem that it takes time to preheat the catalyst body, and that the rise of the combustor is slow.

Further, in preheating using a heater, a heater having a large calorific value cannot be used due to a limit of a watt density on a heater surface, a limit of a supply voltage and a current value, and the like. Therefore, there is a problem that it takes time to preheat the catalyst body.

Further, when starting combustion or changing the supply amount of fuel, a large amount of fuel may be supplied or a small amount of air may be supplied due to a variation in the supply amount of the fuel or air supply device. . In such a case, the air ratio of the air-fuel mixture (the ratio of the supplied air amount to the air amount required to completely burn the supplied fuel) instantaneously becomes 1.
There is a problem that the air may be in a state of shortage of air below 0, CO and HC may be discharged, and a clean combustion state may not be secured.

The present invention, in consideration of these problems of the conventional catalytic combustion apparatus, can efficiently preheat the catalyst body, speed up the start of combustion, and prevent the emission of CO and HC. It is an object of the present invention to provide a catalytic combustion device capable of performing the above.

[0007]

According to the present invention, there is provided a catalyst body using a metal substrate in a combustion chamber into which a mixture of fuel and air flows, and a heat source adjacent to the catalyst body. A solution is provided by providing an exchange unit and joining a heater to the catalyst body.

In order to solve the above-mentioned second problem, the present invention provides a catalyst in a combustion chamber into which a mixture of fuel and air flows, and a high-temperature heat-resistant metal thin wire upstream of the catalyst in the mixture flow direction. The solution is to provide a mat made of and an ignition device between the mat and the catalyst.

In order to solve the third problem, the present invention comprises a combustion chamber into which an air-fuel mixture of fuel and air flows, and a catalyst placed in the combustion chamber. When starting catalytic combustion, increase the supply of fuel and air while maintaining the air ratio of the air-fuel mixture higher than the air ratio during steady-state combustion, and set the fuel supply to the target value during steady-state combustion. After that, setting the air supply amount to a target value is a means for solving the problem.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration sectional view of a catalytic combustion device according to a first embodiment. In FIG.
A combustion chamber 2 is provided downstream of an air-fuel mixture supply unit 1 that supplies an air-fuel mixture of fuel and air. A flat stainless steel fin 3 is provided substantially in parallel in the combustion chamber 2, and a heated fluid flow path 4, which penetrates the fin 3 and flows water as a heated fluid, is joined to the fin 3 by brazing. Is installed. In the vicinity of the fin 3, the first catalyst body 5 is provided substantially in parallel with the fin 3 with a gap. The first catalyst body 5 has a structure in which an alumina layer is formed on the surface of a high-temperature heat-resistant stainless steel sheet and carries a metal mainly composed of a platinum group metal. Further, the downstream portion of the first catalyst body 5 in the air-fuel mixture flow direction protrudes downstream from the location where the fins 3 are present, and is joined to the heater 6 by brazing at the protruding portion. The heater 6 penetrates the first catalyst 5. On the downstream side of the first catalyst 5, an alumina layer is formed on the surface of a cordierite honeycomb having a larger geometric surface area, which is the apparent surface area of the substrate supporting the catalyst, than the first catalyst 5, and platinum is formed. A second catalyst body 7 supporting a metal mainly composed of a group-based metal is provided. An exhaust port 8 is provided downstream of the second catalyst body 7.

The operation of the above configuration will be described.

First, at the time of startup, the heater 6 is energized to generate heat, and the temperature of the first catalyst body 5 is raised. When the temperature of the first catalyst body 5 becomes 600 to 700 ° C., which shows sufficient activity for the city gas as the fuel gas, catalytic combustion is performed by supplying a mixture of city gas and air from the air-fuel mixture supply unit 1. Let it.

The heat generated by the catalytic combustion is transferred to the first catalyst 5
The heat is transferred to the fins 3 provided near the first catalyst body 5 by the radiation from the surface and the convective heat transfer via the combustion gas heated by the first catalyst body 5 having a high temperature. Since the fins 3 are joined to the fluid passage 4 to be heated, the combustion heat generated by the catalytic combustion heats the water flowing in the fluid passage 4 to be heated.
Hot water supply, heating, and the like can be performed by using the heated water. The unburned components that have not been completely reacted by the first catalyst body 5 react on the second catalyst body 7 having a larger geometric surface area than the first catalyst body 5 and are discharged from the exhaust port 8 as clean exhaust gas. Is done.

Here, the heater 6 is joined to the first catalyst body 5 by brazing. Therefore, the thermal conductivity is very good, and the heat generated by the heater is quickly transmitted to the first catalyst 5 and heats the entire first catalyst 5. Therefore, when the air-fuel mixture is supplied, the entire first catalyst body 5 starts catalytic combustion.

In the prior art, the second catalyst body is heated using radiation from a heater to cause catalytic combustion of the second catalyst body, and the first catalyst body is heated by radiation from the second catalyst body to perform catalytic combustion. Therefore, radiant heat transfer was used in two stages before the first catalyst body catalytically burned. In radiant heat transfer, radiation is present in all directions from the high-temperature surface on the heat transfer side, so there is heat radiation to parts other than the heated part, and because the high-temperature surface also raises the temperature of the surrounding air, There is also heat radiation by this heated air. When the heater is joined to the catalyst body, the heat generated by the heater is transmitted to the entire catalyst body by heat conduction, so that the surface of the heater does not become so high in temperature and there is not much heat radiation through the surrounding air. In addition, there is no need to raise the temperature of the second catalyst body 7, and the temperature of the first catalyst body 5 can be directly raised to shift to catalytic combustion. Therefore, the rise time can be considerably reduced by using this configuration.

In this embodiment, the heater 6 is joined to all the catalysts of the first catalyst 5 composed of a plurality of catalysts, but the heater 6 is joined to only a part of the catalysts. It may be. That is, it is also possible to first burn the catalyst joined to the heater, and to heat the other catalyst by the radiant heat transfer from the catalyst to perform the catalyst combustion, thereby starting the combustion of the entire first catalyst. .

FIG. 2 is a sectional view showing the configuration of a catalytic combustion apparatus according to a second embodiment. In FIG. 2, a flat stainless steel fin 3 is provided substantially in parallel in a combustion chamber 2, and a heated fluid channel 4 through which the fin 3 flows and in which water flows is joined to the fin 3 by brazing. Has been installed. In the vicinity of the fin 3, the first catalyst 9 is provided substantially in parallel with the fin 3 with a space provided therebetween. A second catalyst body 10 pierced by a heater 11 is provided downstream of the first catalyst body 9 in the combustion chamber 2, and has an exhaust port 8 downstream of the second catalyst body 10. A plurality of second catalyst bodies 10 are provided substantially in parallel with the flow direction, and are joined to the heater 11 by brazing.

The first catalyst body 9 and the second catalyst body 10 both use an alumina layer formed on the surface of a high-temperature heat-resistant stainless steel plate and carry a metal mainly composed of a platinum group metal. .

The operation of the above configuration will be described.

First, at the time of startup, the heater 11 is energized to generate heat, and the temperature of the second catalyst body 10 is raised. The temperature of the second catalyst body 10 is sufficient to show sufficient activity for city gas 600
When the temperature becomes about 700 ° C., the second catalyst body 10 performs catalytic combustion by supplying a mixture of city gas and air from the mixture supply unit 1. Due to the radiation from the upstream portion of the second catalyst body 10 that has been heated to a high temperature by the catalytic combustion, the downstream portion of the first catalytic body 9 is heated to start catalytic combustion, and eventually the entire first catalytic body 9 performs catalytic combustion. The heat generated by the catalytic combustion on the first catalytic body 9 is radiated from the surface of the first catalytic body 9 and the fins are conveyed by the convective heat transfer through the combustion gas heated by the first catalytic body 9 at a high temperature. It is conveyed to 3. Since the fins 3 are joined to the heated fluid flow path 4, the water flowing in the heated fluid flow path 4 is heated and can be used for hot water supply, heating, and the like. The unburned components from the first catalyst body 9 react in the second catalyst body 7,
The exhaust gas is exhausted from the exhaust port 8 as clean exhaust gas.

Here, in this configuration, after the catalytic combustion is performed by the second catalytic body 10 joined to the heater 11, the first catalytic body 9
However, unlike the first embodiment, the catalyst body joined to the heater is installed as the second catalyst body, so that the heat exchange fins are close to each other as in the configuration of the first catalyst body. There is no need to provide the catalyst body with a certain size so that it can be installed and exchange heat, and the catalyst body can be made considerably smaller. Therefore, the heat capacity of the second catalyst body is reduced, and the temperature of the second catalyst body can be quickly raised by heating the heater. Therefore, even if the first catalytic body 9 is catalytically burned after the second catalytic body 10 is catalytically burned, it can be started up in a short time.

As shown in FIG. 3, if at least a part of the upstream portion or the downstream portion of the second catalyst body 10 is bent so as to block the flow direction of the air-fuel mixture, the second catalyst 10 can be brought into contact with the first catalyst body. The projection area of the medium 10 becomes large (the view factor becomes large), and the radiation from the second catalyst body 10 can be efficiently transmitted to the first catalyst body 9. The transfer characteristics are improved, and the reactivity of the second catalyst body 10 can be improved.

FIG. 4 is a sectional view showing the configuration of a catalytic combustion device according to a third embodiment.

In FIG. 4, flat stainless steel fins 3 are provided substantially in parallel in the combustion chamber 2, and a heated fluid flow path 4 through which the fins 3 flow and water is brazed to the fins 3. It is installed by joining. In the vicinity of the fin 3, the first catalyst body 9 is disposed substantially parallel to the fin 3 with a gap provided therebetween. The first catalyst body 9 has a structure in which an alumina layer is formed on the surface of a high-temperature heat-resistant stainless steel plate and carries a metal mainly composed of a platinum group metal. On the downstream side of the first catalyst body 9, an alumina layer is formed on the surface of the cordierite honeycomb, and a second catalyst body 7 carrying a metal mainly composed of a platinum group metal is installed. It has an exhaust port 8.

On the upstream side of the first catalyst body 9 in the combustion chamber 2,
A high-temperature heat-resistant metal thin wire with a wire diameter of 20 to 100 μm has a porosity of 70 to 80.
And a mat 12 having a thickness of 5 mm and a mat 12
An ignition device 13 that can fly a spark is installed in the vicinity of the downstream side.

The operation of the above configuration will be described.

At the time of startup, the mixture is supplied from the mixture supply unit 1 while the spark is being emitted by the ignition device 13, and a flame is formed on the mat 12. The first catalyst body 9 and the second catalyst body 7 are heated by the flame. The temperature of the first catalyst body 9 is 600 to 600 which shows sufficient activity for city gas.
When the temperature reaches 700 ° C., the supply of the city gas is temporarily stopped to extinguish the flame, and the city gas is supplied again to cause the first catalyst body 9 and the second catalyst body 7 to perform catalytic combustion. The heat generated by the catalytic combustion on the first catalyst body 9 is transferred to the fins 3 to heat the water in the fluid passage 4 to be heated and used for hot water supply and heating. Further, since the second catalyst 7 is provided, the exhaust gas is discharged from the exhaust port 8 in a clean state.

Here, if a mat of a high-temperature and heat-resistant thin metal wire is used as a flame holding portion at the time of preheating, uniform surface combustion on the surface of the mat 12 can be realized with a high load. Therefore, the catalyst body flows with a very large amount of heat and can be uniformly heated in the vertical direction, so that the first catalyst body can be heated to a temperature having sufficient activity in a short time, and the start-up time is greatly reduced. it can. In addition, there is almost no flame length due to surface burning, and the thickness of the mat is 5 m.
m without the need to increase the size of the combustor.
It can be configured by merely providing some space upstream of the catalyst body 9.

The mat 12 may be of any type as long as it can hold a flame such as a ceramic porous body and can realize a high-load surface burning state.

The ignition device may be one that ignites by a spark or one that locally forms a high-temperature portion such as a heater and ignites.

FIG. 5 is a sectional view showing the configuration of a catalytic combustion apparatus according to a fourth embodiment. In FIG. 5, a fin 3 which is a heat exchange part, a fluid passage 4 to be heated, and a first catalyst body 5 joined to a heater 6 are provided in the vicinity of the fin 3 and the heated fluid flow path 4. Further, a second catalyst body 7 is provided downstream of the first catalyst body 9 in the combustion chamber 2, and an exhaust port 8 is provided further downstream. An air supply device 1 that supplies air while controlling the flow rate of air is provided upstream of the air-fuel mixture supply unit 1 at the most upstream part of the combustion chamber 2.
4 and a fuel supply device 15 for supplying the city gas while controlling the flow rate thereof. The fuel supply device 15 is connected to the mixture supply unit 1 via the mixture unit 16.

The operation of the above configuration will be described.

First, at the time of start-up, as in the first embodiment, the heater 6 is energized to raise the temperature of the first catalyst 5 to a temperature at which the catalyst has sufficient activity, and the mixture is allowed to flow to cause the catalyst to flow. At this time, the combustion is started. At this time, the supply amounts of the city gas and the air are increased by the air supply device 14 and the fuel supply device 15 while maintaining the air ratio larger than the air ratio at the time of the steady combustion. Then, after the supply amount of the city gas is set to a target value, excessively supplied air is reduced and the target supply amount is set. That is, in normal catalytic combustion, the air ratio is set at about 1.2 to 1.4, but at startup, 1.4 to 1.6.
And increase the supply of the air-fuel mixture, and after the supply of city gas is set to the desired value, increase the air ratio to 1.2 to 1.4.
Set to. Unlike flame combustion, catalytic combustion can stably burn even under high air ratio conditions where the flame becomes unstable or blows out, so the supply of air changes in an excessive state as described above. It is possible to do. Therefore, even if the supply ratio of the city gas or air supply device is deviated and the air ratio fluctuates, the possibility that the air ratio falls below 1.0 becomes extremely low, and CO and HC
Discharge can be prevented.

Next, when the combustion conditions are changed during the catalytic combustion to increase the supply amount of the city gas, the air supply device 14 and the fuel supply device 15 use the gas ratio of the city gas and the air in a state larger than the air ratio at the time of the steady combustion. After the supply amount is increased and the supply amount of the city gas reaches a target value, the amount of air supplied excessively is reduced to set the target air amount.

Also, when the combustion conditions are changed during the catalytic combustion to reduce the supply amount of the city gas, the air supply device 14 and the fuel supply device 15 allow the city gas and the air to have a larger air ratio than the steady combustion. After the supply amount of city gas reaches a target value, the amount of air supplied excessively is reduced to set the target air amount.

By performing such an operation, even when the supply amount of fuel is changed at the time of catalytic combustion, the amount of C
A clean exhaust gas state can be maintained without discharging O and unburned components.

In the first to fifth embodiments, city gas is used as the fuel. However, gas fuel such as methane, propane, butane or hydrogen may be used, or liquid fuel such as kerosene or gasoline may be used. It may be used after being vaporized.

Although the heat exchange of the high-temperature combustion gas discharged from the second catalyst body is not performed, a heat exchanger such as a fin tube is installed downstream of the exhaust port, or the entire combustor is used. If the exhaust gas is circulated in the water jacket by covering with the water jacket, the heat of combustion can be efficiently exchanged.

Furthermore, if the fin surface, which is the heat receiving portion, is made of a black paint having high heat resistance and the fin surface is made to have a high radiation coefficient by sandblasting or surface treatment, the heat exchange efficiency of combustion heat can be further improved. Can be.

Although water is used as the fluid to be heated, oil, refrigerant, air, etc. may be used depending on the application.

[0041]

As is apparent from the above description, according to the present invention, the heat exchange portion is joined to the catalyst body of the adjacent metal substrate by the preheating heater, so that the heat generated by the heater is transferred to the catalyst body by heat conduction. By transmitting the heat, the catalyst body can be efficiently preheated, and the rise of combustion can be accelerated.

If a high-temperature heat-resistant mat is installed upstream of the catalyst body and a flame is formed on the mat during preheating, the entire catalyst body can be heated with a large amount of heat. Can be even faster.

Further, when starting combustion or changing the supply amount of fuel, if the supply amount of fuel and air is changed in a state larger than the air ratio at the time of steady combustion, the supply amount of fuel or air will vary. Does not occur, the air ratio does not fall below 1.0, and the emission of CO and HC can be prevented.

[Brief description of the drawings]

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

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

FIG. 3 is a configuration diagram of another shape of a second catalyst body in a catalytic combustion device according to a second embodiment of the present invention.

FIG. 4 is a configuration sectional view of a catalytic combustion device according to a third embodiment of the present invention.

FIG. 5 is a configuration sectional view of a catalytic combustion device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air-fuel mixture supply part 2 Combustion chamber 3 Fin 4 Heated fluid flow path 5 First catalyst body 6 Heater 7 Second catalyst body 8 Exhaust port 9 First catalyst body 10 Second catalyst body 11 Heater 12 Mat 13 Ignition device 14 Air Supply device 15 Fuel supply device 16 Mixing section

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tatsuo Fujita 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 3L034 BA23 BA29 BB02

Claims (14)

[Claims] A combustion chamber into which a mixture of fuel and air flows;
A catalyst body using a metal substrate, provided in the combustion chamber, and a heat exchange unit disposed adjacent to the catalyst body, wherein a heater is joined to the catalyst body. Catalytic combustion device. 2. The heat exchange section has a plurality of fins provided substantially parallel to each other, and a fluid passage to be heated joined to the fins, wherein the catalyst body is provided substantially parallel between the fins. The catalytic combustion device according to claim 1, wherein the catalytic combustion device has a shape of a catalyst. 3. The catalytic combustion device according to claim 2, wherein said heater penetrates through said catalyst body. 4. The catalyst body has a portion protruding from a downstream end of the heat exchange unit with respect to a flow direction of the air-fuel mixture.
4. The catalytic combustion device according to claim 3, wherein the protruding portion of the catalyst body is joined to the heater. 5. The catalyst according to claim 1, wherein a second catalytic body having a larger geometric surface area than the catalytic body is provided downstream of the catalytic body. Combustion equipment. 6. A combustion chamber into which a mixture of fuel and air flows,
A first catalyst body using a metal substrate, provided in the combustion chamber, and a heat exchange unit disposed adjacent to the first catalyst body, wherein the first catalyst body in the combustion chamber, A catalytic combustion device, wherein a second catalytic body made of a metal substrate is provided on a downstream side with respect to a flow direction of the air-fuel mixture, and the second catalytic body is joined to a heater. 7. The catalytic combustion apparatus according to claim 6, wherein a plurality of the second catalytic bodies are provided in parallel with a flow direction of the air-fuel mixture. 8. The catalytic combustion apparatus according to claim 7, wherein at least a part of an upstream portion or a downstream portion of the second catalyst body has a shape bent so as to block a flow of an air-fuel mixture. 9. A combustion chamber into which a mixture of fuel and air flows,
A catalyst body provided in the combustion chamber; a high-temperature heat-resistant mat disposed in the combustion chamber and upstream of the catalyst body with respect to a flow direction of the air-fuel mixture; A catalytic combustion device comprising: an ignition device provided between the catalytic combustion device and a medium. 10. The catalytic combustion apparatus according to claim 9, wherein said mat is made of a thin metal wire. 11. A heat exchange section is provided in the combustion chamber at a position adjacent to the catalyst body, wherein the heat exchange section includes a plurality of fins substantially parallel to each other and a fluid passage to be heated joined to the fins. The catalytic combustion device according to claim 9, wherein the catalytic body is a plate-like catalytic body disposed substantially in parallel between the fins. 12. A combustion chamber into which a mixture of fuel and air flows, and a catalyst body provided in the combustion chamber, wherein after preheating, the mixture is supplied to start catalytic combustion.
The air ratio of the air-fuel mixture, increasing the supply amount of the fuel and the air in a state larger than the air ratio at the time of steady combustion,
A catalytic combustion apparatus, wherein the supply amount of air is set to a target value after the supply amount of fuel is set to a target value in steady combustion. 13. A combustion chamber into which a mixture of fuel and air flows, and a catalyst disposed in the combustion chamber, wherein when the supply amount of the fuel is increased during steady combustion, the air ratio during steady combustion is increased. And increasing the supply amounts of the fuel and the air in a larger state, setting the supply amount of the fuel to a target value, and then setting the supply amount of the air to a target value. apparatus. 14. A combustion chamber into which a mixture of fuel and air flows, and a catalyst provided in the combustion chamber, wherein when the supply amount of the fuel is reduced during steady combustion, the air ratio during steady combustion is reduced. And reducing the supply amounts of the fuel and the air in a larger state, setting the supply amount of the fuel to a target value, and then setting the supply amount of the air to a target value. apparatus.