JPH1151310A - Catalytic combustion device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] During catalytic combustion of a fuel containing methane as a main component that is difficult to react, the temperature of a region where the activity of the catalyst body is low decreases, causing a decrease in the temperature around the region. An object of the present invention is to provide a catalytic combustion device in which the reactivity of the entire medium is deteriorated, and in which a stable combustion state and excellent exhaust gas characteristics are obtained even when a fuel gas containing methane as a main component is used. SOLUTION: A fuel supply valve 1 for supplying fuel, an air supply valve 2 for supplying air for combustion, a premixing chamber 3 for mixing fuel and air to produce a mixed gas, and catalytically burning the mixed gas. A catalyst body 10 composed of a porous body, a first combustion chamber 11 containing the catalyst body 10, a mixing chamber 13, a second air supply valve 12 for supplying another air for combustion to the mixing chamber 13, A catalytic combustion device comprising a second combustion chamber 15 for accommodating a second catalytic body 14 made of a porous body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for gaseous or liquid fuel, and uses the generated heat and exhaust gas to perform heating, heating, drying, etc., with good exhaust gas characteristics. The present invention relates to a catalytic combustion device.

[0002]

2. Description of the Related Art Conventionally, a catalytic combustion apparatus for performing heating, heating, drying, etc. by catalytically burning gaseous fuel or liquid fuel is shown in FIG.
The configuration shown in FIG.

The configuration will be described with reference to FIG.
In FIG. 7, the fuel gas supplied from the first fuel supply valve is mixed with the air supplied from the second air supply valve in the premixing chamber 3 and sent to the preheating burner 4 as a premixed gas. The premixed gas is ignited by the ignition device 5 and forms a flame in the preheating burner 4. The high-temperature exhaust gas generated by the flame passes through the catalyst 7 provided in the combustion chamber 6 while heating, and is discharged from the exhaust port 8. Once the temperature of the catalyst body 7 rises to a level having activity, once the fuel supply valve 1
To stop the fuel supply and extinguish the flame. Immediately thereafter, refueling starts the catalytic combustion. The catalyst body was in a high temperature state, and radiated and radiated through the glass 9 provided at a position facing the upstream side of the catalyst body, and radiated heat as high-temperature exhaust gas from the exhaust port 8 to perform heating and heating.

[0004]

In such a conventional catalytic combustion device, Pt or Pd is generally used as a combustion catalyst.
It is known that Pt is excellent in heat resistance and Pd is excellent in low-temperature reactivity. When performing catalytic combustion using a fuel containing methane as a main component, which has a stable molecular structure and is hardly oxidized, a catalyst containing Pd as the main component, which has excellent reactivity at low temperatures, should be used. Many.

However, Pd is easily oxidized and reduced depending on the temperature and the state of the surrounding oxygen, and dissociates with PdO. Generally, this dissociation temperature is about 800 ° C.

However, in order to use the combustion heat generated by catalytic combustion as radiant heat as effectively as possible, it is necessary that the temperature of the catalyst body be as high as possible below the heat resistance limit of the catalyst. The maximum heat-resistant temperature of the catalyst body is about 850 ℃
Therefore, the operating temperature range of the catalyst body is around 800 ° C.

Therefore, when the catalyst is used in this temperature range, since the catalyst has a region higher and lower than the dissociation temperature, the catalyst becomes a catalyst in which Pd and PdO are mixed, and the difference between the activities of Pd and PdO is different. Thus, an unstable catalyst body is obtained in which a region having good catalytic activity and a region having poor catalytic activity coexist.

For this reason, if a methane-based fuel which is difficult to react is used, the temperature of the catalyst body is reduced in a region on the catalyst body where the catalytic activity is poor, and the temperature around the catalyst body is also reduced. By repeating this phenomenon, there is a problem in that the reactivity of the entire catalyst body eventually deteriorates and combustion stops.

Further, in the conventional catalytic combustion apparatus, heating, heating, drying, etc. are performed by utilizing the direct radiation from the surface of the catalyst body, the high-temperature exhaust gas, and the heat radiation from the surface of the catalytic combustion apparatus by performing catalytic combustion. Had gone. However, this method has a problem in that when a specific place or object is locally heated or heated, the heat radiation to a portion other than the object to be heated increases, resulting in a catalytic combustion device having a low heat exchange efficiency. there were.

Further, when the sensible heat of the combustion gas is exchanged with a heat exchanger such as a fin tube, if the heat exchanger is installed above the catalyst, the combustion heat rises when the combustion device is started. Since the exhaust gas temperature is not so high because it is deprived of the temperature, there is a possibility that dew water is generated on the heat exchanger and the catalyst body is wetted. When the catalyst is wetted with dew condensation water, the temperature is lowered, the catalytic reaction is reduced, and the reaction characteristics may be locally reduced. In addition, since dew condensation cannot be performed on the heat exchanger, aggressive heat exchange cannot be performed, and the latent heat in the combustion gas must be discharged as exhaust loss without being recovered.

In view of the above, the present invention provides a catalytic combustion apparatus using a catalyst body mainly composed of a Pd catalyst even when a fuel gas mainly composed of methane is used. An object of the present invention is to obtain a catalytic combustion device having good exhaust gas characteristics in a state.

Further, the present invention exchanges heat of combustion by using a heat medium, thereby minimizing heat loss to other than the object to be heated, realizing a compact catalytic combustion device having high heat exchange efficiency and high efficiency. The purpose is to:

Further, according to the present invention, a combustion chamber is provided above a heat exchanger, and the condensed water generated on the heat exchanger is discharged to the outside of the catalytic combustion device. The purpose of the present invention is to prevent combustion and maintain a stable combustion state. At the same time, another object of the present invention is to realize a catalytic combustion device having extremely high heat exchange efficiency by recovering latent heat in combustion gas.

[0014]

According to a first aspect of the present invention, there is provided a fuel supply unit for supplying fuel, a first air supply unit for supplying air for combustion, A premixing chamber that mixes fuel supplied from the fuel supply unit and air supplied from the first air supply unit to form a mixed gas, and burns the mixed gas generated in the premixing chamber;
A first combustion chamber containing a first catalyst body made of a porous body, an ignition section for igniting the first catalyst body and the mixed gas, and a first combustion chamber downstream of the first combustion chamber. A mixing chamber provided, a second air supply unit for supplying another air for combustion to the mixing chamber, and a second catalyst body provided downstream of the mixing chamber and formed of a porous body And a second combustion chamber for accommodating the fuel, wherein the fuel has methane as a main component, the first catalyst body has a Pd catalyst as a main component, and the fuel supply unit and the first
The air supply unit supplies the fuel and the air such that the air ratio in the premixing chamber is less than 1, and the second air supply unit makes the air ratio in the mixing chamber become 1 or more. Thus, the catalytic combustion device is characterized by supplying air.

According to a second aspect of the present invention, there is provided a fuel supply unit for supplying fuel, an air supply unit for supplying air for combustion, fuel supplied from the fuel supply unit, and supplied from the air supply unit. A premixing chamber for mixing air to produce a mixed gas;
The mixed gas is catalytically burned, and a plate-shaped catalyst body made of a porous body is provided on the downstream side of the premixing chamber, and the plate-shaped catalyst body is housed therein. And a combustion chamber in which the first radiant heat receiving portion is disposed opposite to one of the surfaces and has a part of the side wall.

[0016] The first radiation heat receiving portion may have a heat medium flow path in close contact or with a built-in heat medium flow path.

[0017] The combustion chamber may include a second radiant heat receiving portion disposed opposite to another one of both surfaces of the catalyst body as a part of a side wall.

Further, the second radiant heat receiving section may have a heat medium flow path in close contact or with a built-in heat medium flow path.

Further, a plate-like second catalyst body made of a porous body may be provided at the outlet of the combustion chamber.

Further, a radiation absorption layer may be provided on a surface of the first radiation heat receiving portion inside the combustion chamber.

Further, a radiation absorption layer may be provided on a surface of the second radiation heat receiving portion inside the combustion chamber.

Further, the catalytic combustion device may further include a heat exchange unit provided downstream of the combustion chamber, and the combustion chamber may be located above the heat exchange unit.

According to a tenth aspect of the present invention, there is provided a fuel supply unit for supplying fuel, an air supply unit for supplying air for combustion, fuel supplied from the fuel supply unit, and supplied from the air supply unit. A premixing chamber that mixes air to form a mixed gas, a catalytic body that catalytically burns the mixed gas, a combustion chamber that houses the catalytic body, and a heat exchange unit that is arranged downstream of the combustion chamber. Wherein the temperature of the exhaust gas discharged from the heat exchanger is equal to or lower than the dew point temperature of the heat exchanger.

Next, examples of the operation of the present invention will be described as follows.

In a catalytic combustion apparatus provided with a two-stage catalytic body, the mixing ratio of fuel and air is reduced to less than 1 in a first combustion chamber having a first catalytic body mainly composed of a Pd catalyst. Let it. When the air ratio is less than 1, there is not enough air to completely burn the supplied fuel, and all the oxygen in the supplied air is used for burning the fuel. Therefore, there is no oxygen available for the oxidation of Pd to PdO,
The catalyst does not change to PdO, and can maintain a stable catalyst state and continue a stable combustion state.

However, if catalytic combustion is performed at an air ratio of less than 1, the air supply amount (oxygen amount) is insufficient with respect to the fuel supply amount, so that the unburned components in the fuel gas are less than the first catalyst body. Is discharged.

Therefore, a mixing chamber is provided downstream of the first combustion chamber, and fresh air is supplied and mixed with unburned fuel gas to make the air ratio 1 or more. Then, if catalytic combustion is performed by the second catalytic body in the second combustion chamber provided downstream of the mixing chamber,
An unburned component can be burned, and a catalytic combustion device having excellent exhaust gas characteristics can be obtained.

In general, the catalytic combustion device burns under the condition that the upstream portion of the catalyst body has the highest temperature, and utilizes a large amount of radiation and radiation from the high temperature upstream surface of the catalyst body.

Therefore, if a plate-shaped catalyst having a large apparent catalyst body surface area is used and a radiation heat receiving portion is provided at a position facing the catalyst, a large amount of radiant heat transfer from the surface of the catalyst is transferred to the radiation heat receiving portion. Can receive heat. Since the flow path of the heat medium is closely attached to or contained in the received radiation heat receiving portion, heat is transferred to the heat medium flow path, and heat exchange is performed with the heat medium in the flow path.

Here, since the heat transfer to the radiation heat receiving portion is radiation heat transfer, heat can be uniformly removed from the entire catalyst body. For this reason, since the temperature unevenness that occurs when the combustion heat is deprived from a part of the catalyst body by direct heat conduction cannot be generated, a large amount of combustion heat on the catalyst body can be transmitted to the heat medium while maintaining a stable combustion state. In addition, since the temperature of the upstream surface, which is the highest temperature portion of the catalyst body, can be lowered by active heat exchange by the radiation heat receiving unit, it is possible to increase the amount of combustion without raising the temperature of the catalyst body to the heat-resistant limit temperature. it can. Therefore, it is possible to realize a compact catalytic combustion apparatus that performs heat exchange using a heat medium.

Further, if the first and second radiant heat receiving portions are provided opposite to both surfaces of the plate-like catalyst body, radiation from both surfaces of the catalyst body is captured by the first and second radiant heat receiving portions. At the same time as the heat exchange, the outer wall of the catalytic combustion device is constituted by the first and second radiant heat receiving portions, so that the temperature of the outer wall of the catalytic combustion device can be kept low. Therefore, heat radiation loss due to natural convection heat radiation and radiation heat radiation from the outer wall of the catalytic combustion device can be reduced, and the heat exchange efficiency can be increased.

Further, the heat radiation of the catalyst body to the second radiation heat receiving portion lowers the temperature of the catalyst body facing the first radiation heat receiving portion, and the catalyst body on the side facing the first radiation heat receiving portion due to heat conduction in the catalyst body. , The combustion amount can be further increased. Therefore, a catalytic combustion device with high heat exchange efficiency can be realized more compactly.

Further, if the second catalyst is provided downstream of the combustion chamber, the radiant heat from the second catalyst can be received by the radiant heat receiving portion. Can be enhanced. At the same time, unburned components slightly discharged from the first catalyst body are burned, so that a catalytic combustion device having good exhaust gas characteristics can be realized.

Further, if a radiation absorption layer is provided on the surface of the radiation heat receiving portion, radiation from the surface of the catalyst can be received by the radiation heat receiving portion very efficiently, so that the heat exchange efficiency can be further improved. .

If the catalyst is disposed on the heat exchange part for recovering the sensible heat in the combustion gas generated by the catalyst, even if dew condensation occurs on the heat exchange part under some conditions, the dew condensation water Is dropped from the heat exchange part in the exhaust direction and discharged to the outside of the catalytic combustion device.

Therefore, a stable combustion state can be maintained without disturbing the combustion state by wetting the catalyst body. Here, in the case of flame combustion, since the combustion gas contains NOX, the pH value of the condensed water is 3 or less.In the case of catalytic combustion, however, almost no NOX is contained. Almost no components other than the dissolved components of CO ₂ and H ₂ O are contained. Therefore, the pH is 6, and the heat exchanger is not corroded by dew condensation water.

As a result, since the latent heat in the combustion gas can be recovered by performing the active heat exchange, it is possible to realize a catalytic combustion device having extremely high heat exchange efficiency.

[0038]

Embodiments of the present invention will be described below with reference to the drawings.

A catalytic combustion device according to a first embodiment of the present invention will be described with reference to FIG. Fuel supply valve 1 for controlling fuel gas supply
And an air supply valve 2 for controlling the air supply amount, and is connected to the premixing chamber 3. Downstream of the premixing chamber 3 is a preheating burner 4, which is a first catalyst body 1 that supports a catalyst composed mainly of Pd based on a ceramic honeycomb that is a porous body.
It continues to zero. Downstream of the first catalyst body 10, the second
A mixing chamber 13 having an air supply valve 12 of
It is connected to the second combustion chamber 15 and further to the exhaust port 8. The second combustion chamber 15 has a second catalyst 14
Is provided, and a glass 9 is provided at a position facing the upstream surface of the first catalyst body 10.

In the above configuration, the fuel gas and air supplied from the fuel supply valve 1 and the air supply valve 2 are mixed in the premixing chamber 3 and supplied to the preheating burner 4. A flame is formed in the preheating burner 4 by the ignition device 5 in the vicinity of the preheating burner 4, and the temperature of the first catalyst body 10 is increased by high-temperature exhaust gas generated from the flame. When the temperature of the first catalyst body 10 becomes active, the supply of fuel gas is once stopped by the fuel supply valve 1 to extinguish the flame. Immediately thereafter, the first catalyst 10 starts catalytic combustion by supplying fuel gas through the fuel supply valve 1.

At this time, the fuel gas amount and the air amount are adjusted by the fuel supply valve 1 and the air supply valve 2 so that the air ratio becomes less than 1.0. Further, air is supplied by the second air supply valve so that the air ratio becomes 1.0 or more in the second combustion chamber.

In the first catalyst 10, since the premixed gas has an air ratio of less than 1.0, all of the oxygen in the premixed gas is used for the oxidation reaction of the fuel gas.
There is no oxygen for the Pd catalyst to dissociate into PdO, and the first catalyst body 10 has only the Pd catalyst.
Stable catalytic combustion can be performed even at around 800 ° C, the Pd dissociation temperature.

The high temperature combustion gas discharged from the first catalyst body 10 raises the temperature of the second catalyst body 14 to a temperature having catalytic activity. Here, the mixing chamber 13
Then, air is supplied to the combustion gas containing unburned components from the first catalyst body 10 by the second air supply valve 12 so as to have an air ratio of 1.0 or more, mixed and supplied to the second combustion chamber 15. Then, the unburned components burn in the second catalyst body 14, and
The exhaust gas is discharged from the exhaust port 8 as an exhaust gas containing no unburned components.

As described above, even when a fuel containing methane as a main component is used, stable catalytic combustion can be performed, and a catalytic combustion device having good exhaust gas characteristics can be realized.

A catalytic combustion device according to a second embodiment of the present invention will be described with reference to FIG. Fuel supply valve 1 for controlling fuel gas supply
And an air supply valve 2 for controlling the air supply amount, and is connected to the premixing chamber 3. A preheating burner 4 is provided downstream of the premixing chamber 3, and a catalyst body 7 based on a plate-shaped ceramic honeycomb having a large apparent surface area is provided downstream of the premixing chamber 3, and continues to an exhaust port 8. At a position facing the upstream surface of the catalyst body 7, a radiant heat receiving plate 17 in which the heat medium flow path 16 is in close contact is provided.

In the above configuration, the fuel gas supplied from the fuel supply valve 1 and the air supplied from the air supply valve 2 are mixed in the premixing chamber 3 and supplied to the preheating burner 4. A flame is formed in the preheating burner 4 by the ignition device 5 in the vicinity of the preheating burner 4, and the temperature of the catalyst body 7 is increased by high-temperature exhaust gas generated from the flame. At this time, the heat medium flows through the heat medium flow path 16. When the temperature of the catalyst 7 becomes active, the supply of the fuel gas is temporarily stopped by the fuel supply valve 1 to extinguish the flame. Immediately thereafter, the fuel gas is supplied from the fuel supply valve 1 to start catalytic combustion in the catalyst body 7.

The heat medium receives a large amount of heat while passing through the heat medium flow path 16 and is heated to become a high-temperature heat medium. By using this heat medium, it is possible to heat or heat only a specific object or place. For example, a water heater can be realized by directly using a heat medium as water, and it can be used as floor heating by flowing a heat medium through a pipe routed under the floor.

At the time of catalytic combustion, the upstream surface of the plate-shaped catalyst 7 is at a high temperature of 800 ° C. to 850 ° C. due to combustion heat, and a large amount of radiation is radiated from the upstream surface of the catalyst 7.
Since the radiation heat receiving plate 17 is provided at a position facing the upstream side of the catalyst body 7, the radiation heat receiving plate 17 receives a large amount of radiation from the catalyst body 7. Since the heat medium flow path 16 is in close contact with the radiation heat receiving plate 17 and the heat medium is flowing, the amount of heat received by the radiation heat receiving plate 17 is transferred to the heat medium by heat conduction, and the temperature of the heat medium rises.

Here, in this configuration, since the heat transfer from the catalyst 7 to the radiation heat receiving plate 17 is performed by radiation, the heat can be uniformly removed from the entire surface of the catalyst body 7. , The surface of the catalyst body 7 is at a uniform temperature. If the heat of the catalyst 7 is directly transferred by heat conduction, the temperature of the catalyst in the vicinity of the portion from which the heat is taken decreases, and the temperature becomes uneven on the catalyst 7 and the combustion state becomes unstable. Possibilities arise.

Therefore, by using the radiation heat receiving plate 17, it is possible to transfer the combustion heat to the heat medium without disturbing the combustion state of the catalyst.

As described above, since the radiant heat from the upstream surface of the catalyst body 7 is substantially transferred to the heat medium, the radiant heat receiving plate 17 in the heat receiving portion has a low temperature. Therefore,
The catalyst body 7 radiates and radiates a large amount of combustion heat from the upstream surface, and the temperature of the catalyst body 7 upstream surface decreases. At the time of catalytic combustion, the temperature of the upstream portion of the catalyst body 7 is the highest, so that the maximum temperature of the catalyst body 7 decreases due to a large amount of radiation and radiation.

For this reason, even if the amount of combustion is increased, the temperature of the catalyst body 7 hardly rises to the heat-resistant limit temperature, so that the amount of combustion can be increased, and a compact catalytic combustion device with respect to the amount of combustion is realized. be able to.

A catalytic combustion device according to a third embodiment of the present invention will be described with reference to FIG. The catalytic combustion device according to the present embodiment also includes a radiation heat receiving plate 19 in which a heat medium flow path 18 is closely attached to a position facing the downstream surface of the catalyst body 7.

At the time of catalytic combustion, the downstream surface of the catalyst body 7 is also in a high temperature state. Therefore, by providing a radiation heat receiving plate 19 at a position to receive the radiation from the downstream surface of the catalyst body 7, Radiated heat can be exchanged with the heat medium, and the heat exchange efficiency of the catalytic combustion device can be increased. In addition, since the temperature of the downstream surface of the catalyst body 7 decreases due to this heat exchange, the temperature of the upstream surface of the catalyst body 7 also decreases. Therefore, since the amount of combustion can be further increased, a more compact catalytic combustion device can be realized.

Further, the radiation heat receiving plates 17 and 19 constitute the wall of the combustion chamber 6, and since the heat of combustion in the catalyst 7 is almost exchanged with the heat medium, the wall temperature of the combustion chamber 6 is not so high. Does not go up. Therefore, there is almost no heat dissipation loss due to natural convection heat transfer or radiation from the walls of the catalytic combustion device, so that the heat exchange efficiency can be increased.

A catalytic combustion device according to a fourth embodiment of the present invention will be described with reference to FIG. The catalytic combustion device in the present embodiment includes a first catalyst body 20 having a plate-shaped ceramic honeycomb as a base and a second catalyst body 14 having a plate-shaped ceramic honeycomb as a base downstream of the radiation heat receiving plate 19. ing.

At the time of catalytic combustion, the temperature of the second catalytic body 14 is raised to a temperature having catalytic activity by the high temperature exhaust gas from the first catalytic body 20. Therefore, some unburned components contained in the combustion gas from the first catalyst body 20 are completely burned by the second catalyst body 14, and are discharged from the exhaust port 8 as exhaust gas containing no unburned components.

At this time, the upstream surface of the second catalyst body 14
The temperature is high due to the combustion gas from the catalyst body 20 and the combustion heat from the second catalyst body 14, and heat is radiated from the upstream surface of the second catalyst body 14 by radiation.

Since the radiation heat receiving plate 19 is provided on the upstream side of the second catalyst body 14, the second catalyst body 1
Radiation from the upstream surface of 4 is received by the radiation heat receiving plate 19 and is exchanged with the heat medium.

As a result, radiated heat from the upstream surface and the downstream surface of the first catalyst body 20 and the upstream surface of the second catalyst body 14 can be exchanged with the heat medium. , A catalytic combustion device with a high temperature can be realized.

A catalytic combustion apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. The catalytic combustion device according to the present embodiment includes a high radiation absorption layer 21 in which a black paint is applied on the inner surface of the radiation heat receiving plate 17.

Since the radiation coefficient of the black paint is 0.9 to 1.0, radiation from the upstream surface of the catalyst body 7 is received by the high radiation absorbing layer 21 very efficiently, and is transferred to the radiation heat receiving plate 17 to be transferred to the heat medium and heat medium. Be exchanged. Therefore, the heat exchange efficiency can be improved. The improvement in heat exchange efficiency increases the amount of heat transferred from the upstream surface of the catalyst body 7 to the radiation heat receiving plate 17, that is, the amount of heat radiation from the upstream surface of the catalyst body 7, so that the temperature of the upstream surface of the catalyst body 7 decreases.

As a result, the amount of combustion can be increased below the heat-resistant limit temperature, so that the catalytic combustion device can be made compact.

In addition, not only the radiation heat receiving plate 17 but also the combustion chamber 6
If a high radiation absorption layer is also provided on the inner surface of the catalyst body 7 and the thermal conductivity with the radiation heat receiving plate 17 is increased, the radiation radiation from the upstream surface of the catalyst body 7 can be reduced by the high radiation absorption layer formed on the entire upstream surface of the catalyst body 7. Heat can be reliably received and heat can be exchanged with the heat medium.

As the high radiation absorbing layer 21, a new layer having a large radiation coefficient may be formed on the surface of the radiation heat receiving plate 17 as in the above-described painting or plating of a black paint, Thus, a fine uneven shape may be formed on the surface of the radiation heat receiving plate to increase the radiation coefficient.

In the first to fifth embodiments, an ignition device may be provided downstream of the catalyst (first catalyst) as the ignition means. In this case, a flame is formed on the downstream side of the catalyst body at the time of ignition, and the temperature of the catalyst body is increased by the flame. When the temperature of the catalytic body becomes active, catalytic combustion starts spontaneously, but at the same time, the flame on the downstream side of the catalytic body is supplied with exhaust gas generated by catalytic combustion, so that the flame is extinguished.
Therefore, if the ignition device is installed downstream of the catalyst body,
It is possible to shift from flame combustion during natural and preheating to catalytic combustion without control of fuel supply. Further, as the ignition device, a preheated gas may be locally raised to the ignition temperature or higher by using a ceramic heater, or a method may be used in which an igniter is used to spark a catalyst frame or a catalytic combustion device wall. .

In the first to fifth embodiments, a heat exchanger such as a fin tube type for recovering sensible heat in exhaust gas is installed downstream of the catalyst 7 or the second catalyst 14. If the heat medium is flown to recover the exhaust heat, the heat exchange efficiency can be further increased.

A catalytic combustion apparatus according to a sixth embodiment of the present invention will be described with reference to FIG. A radiant heat receiving plate 17 having a heat medium flow path 16 is provided at a position facing the upstream surface of the catalyst body 7, and a fin tube type heat exchanger through which a heat medium can flow downward of the catalyst body 7. 22 are installed.

Here, it is known that NOx is hardly contained in exhaust gas in catalytic combustion. For this,
When exhaust gas is condensed, in the case of flame combustion, p
Where H is less than 3, in the case of catalytic combustion,
Since the condensed water contains almost no nitric acid, the pH is 6
The values before and after are shown. Therefore, even if the moisture contained in the combustion gas condenses on the surface of the heat exchanger 22, in the case of catalytic combustion, the surface of the heat exchanger 22 does not corrode due to the condensed water.

The catalytic combustion apparatus according to the present embodiment utilizes this fact positively, so that the temperature of the exhaust gas discharged from the heat exchanger 22 becomes lower than the dew point temperature in the heat exchanger 22. I have. With such a configuration, the combustion gas flowing into the heat exchanger 22 is
When heat is exchanged on the surface of the surface, dew forms on the heat exchange surface. As described above, since the pH of the condensed water of the combustion gas due to catalytic combustion is about 6, there is no problem even if the condensed water adheres to the surface of the heat exchanger 22. Therefore, when heat exchange of the combustion gas discharged by the catalytic combustion is performed in the heat exchanger 22, latent heat exchange can be performed in addition to the conventional sensible heat exchange. Can be improved as compared with the flame combustion method.

The operation of the catalytic combustion apparatus having the above effects will be described with reference to FIG.

The combustion gas generated by the catalyst 7 is supplied to the heat exchanger 22
And heat is exchanged and discharged downward. Heat exchanger 22
Even if the condensed water is generated, the condensed water falls downward in the discharge direction of the combustion gas according to gravity, so that the combustion state of the catalyst body 7 above the heat exchanger 22 is not affected. Therefore, heat exchange is actively performed in the heat exchanger 22, and the latent heat of H ₂ O in the combustion gas can also be exchanged. Further, since the radiant heat from the upstream surface of the catalyst body is exchanged by the radiant heat receiving plate 17 on the upstream side of the catalyst body 7, a catalyst combustion apparatus having extremely high heat exchange efficiency can be realized as a whole of the catalyst combustion apparatus.

Note that a drain passage for collecting and discharging dew water may be provided below the heat exchanger 22.

[0074]

As is evident from the above, in the catalytic combustion apparatus of the present invention using a fuel gas containing methane as a main component, the catalytic body has a two-stage structure, and the upstream catalytic body mainly comprises Pd. As a component, stable combustion is achieved by supplying fuel and air with an air ratio smaller than 1.0 and catalyzing combustion, and supplying new air to the downstream catalytic body so that the air ratio becomes 1.0 or more and catalyzing combustion. It is possible to realize a catalytic combustion device having good exhaust gas characteristics that maintain the combustion state.

Further, a large amount of radiant heat from the surface of the catalyst body is received by a radiant heat receiving plate provided with a heat medium flow path using a plate-shaped catalyst body, and heat exchange is performed with the heat medium. A compact combustion device can be realized. Further, by using the heat medium, it is possible to realize a catalytic combustion device that efficiently heats or heats only a specific place or object.

Further, if the catalyst is arranged on the heat exchanger, a stable combustion state can be maintained even if dew condensation water is generated. also recovered latent heat of H ₂ O, heat exchange efficiency can be achieved very high catalytic combustion apparatus.

[Brief description of the drawings]

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

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

FIG. 3 is a configuration diagram of a catalytic combustion device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a catalytic combustion device according to a fourth embodiment of the present invention.

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

FIG. 6 is a configuration diagram of a catalytic combustion device according to a fifth embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional catalytic combustion device.

[Explanation of symbols]

 Reference Signs List 7 catalyst body 10 first catalyst body 11 first combustion chamber 12 second air supply valve 13 mixing chamber 14 second catalyst body 15 second combustion chamber 16 heat medium flow path 17 radiation heat receiving plate 18 heat medium flow Path 19 Radiation heat receiving plate 20 First catalyst body 21 High radiation absorption layer 22 Heat exchanger

Continued on the front page (72) Inventor Yoshitaka Kawasaki 1006 Kadoma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Jiro Suzuki 1006 Odaka Kadoma Kadoma, Osaka Pref.

Claims (10)

[Claims] 1. A fuel supply unit for supplying fuel, a first air supply unit for supplying air for combustion, a fuel supplied from the fuel supply unit, and a fuel supplied from the first air supply unit A premixing chamber that mixes air to form a mixed gas, a first catalyst body made of a porous body that burns the mixed gas created in the premixing chamber, and the first catalyst body. A first combustion chamber containing an ignition section for igniting the mixed gas, a mixing chamber provided downstream of the first combustion chamber, and a second combustion chamber for supplying another combustion air to the mixing chamber. 2, an air supply unit, and a second combustion chamber provided downstream of the mixing chamber and accommodating a second catalyst body formed of a porous body, wherein the fuel is mainly composed of methane, The first catalyst body is mainly composed of a Pd catalyst, and the fuel supply unit and the first air supply unit Supplying the fuel and the air so that the air ratio in the chamber is less than 1, and supplying the air such that the air ratio in the mixing chamber is 1 or more. Characteristic catalytic combustion device. 2. A fuel supply unit for supplying fuel, an air supply unit for supplying air for combustion, and a mixture of fuel supplied from the fuel supply unit and air supplied from the air supply unit. A premixing chamber for producing a mixed gas, a plate-like catalyst body made of a porous body that catalytically burns the mixed gas, and a plate-like catalyst body provided downstream of the premixing chamber and containing the plate-like catalyst body And a combustion chamber having a first radiant heat-receiving portion disposed as a part of the side wall, the combustion chamber being disposed so as to face one of the two surfaces of the catalyst body. 3. The catalytic combustion device according to claim 2, wherein the first radiant heat receiving section has a heat medium flow path in close contact with or inside the heat medium flow path. 4. A side wall of the combustion chamber, wherein a second radiant heat receiving portion disposed opposite to another of the two surfaces of the catalyst body is a part of a side wall. A catalytic combustion device as described in the above. 5. The catalytic combustion device according to claim 4, wherein the second radiation heat receiving portion has a heat medium flow passage in close contact with or inside the heat medium flow passage. 6. The catalytic combustion apparatus according to claim 4, wherein a plate-shaped second catalyst body made of a porous body is provided at an outlet of the combustion chamber. 7. The catalytic combustion device according to claim 2, wherein a radiation absorption layer is provided on a surface of the first radiation heat receiving portion inside the combustion chamber. 8. The catalytic combustion device according to claim 4, wherein a radiation absorption layer is provided on a surface of the second radiation heat receiving portion inside the combustion chamber. 9. The catalytic combustion device further includes a heat exchange unit provided downstream of the combustion chamber, wherein the combustion chamber is located above the heat exchange unit. 4. The catalytic combustion device according to 2 or 3. 10. A fuel supply unit for supplying fuel, an air supply unit for supplying air for combustion, and a mixture of fuel supplied from the fuel supply unit and air supplied from the air supply unit. A premixing chamber for producing a mixed gas, a catalytic body for catalytically burning the mixed gas, a combustion chamber for accommodating the catalytic body, and a heat exchange unit disposed downstream of the combustion chamber. The temperature of exhaust gas discharged from the section is lower than the dew point temperature of the heat exchanger.