JPH0623606B2 - Combustion device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for burning using liquid or gas fuel, and is used as a heating heat source for heating, drying, hot water supply, and the like.

2. Description of the Related Art A conventional catalytic combustion device is shown in FIG. In FIG. 3, reference numeral 1 denotes a catalyst body having a large number of combustion holes 2. The mixture of fuel gas and air enters the premix chamber 4 through the premix pipe 3 and burns in the combustion holes 2. The combustion reaction raises the temperature of the catalyst body 1 and the heat is radiated through the glass 5 provided on the outer periphery. Exhaust gas is discharged downstream of the catalyst body 1. Further, a heater 6 for preheating and ignition is provided upstream of the catalyst body 1.

Problems to be Solved by the Invention However, such a configuration has a drawback in that high load combustion is difficult. The reason will be described below. When a large amount of fuel gas is burned by the catalyst body 1 having a limited area, the temperature of the catalyst body 1 increases according to the combustion amount. Due to this increase in temperature, the life of the catalyst deteriorates. The premixed gas in the premixed air chamber 3 is ignited. Therefore, there is a limit to the amount of combustion per unit area. In order to prevent such a problem, the temperature of the catalyst body 1 is prevented from rising by using a material having a thin glass 5 and good heat permeability, or the catalyst body 1 is loaded with a platinum group-based catalyst to prevent Conventionally, measures such as suppressing ignition of mixed gas have been taken.

The present invention further fundamentally solves such problems, increases the amount of combustion per unit area, and enables high-load combustion with a more compact catalyst body.

Means for Solving the Problems And a technical means of the present invention for solving the above problems is to provide a catalyst body having a large number of combustion holes, which is supplied with a mixture of fuel and air. The cooling path provided via the above is used as a component, and the surface of the cooling path facing the catalyst body is subjected to radiation absorption surface treatment.

Action The action of this technical means is as follows. That is, the catalyst body is cooled from the outer periphery by the fluid that cools the outer periphery of the catalyst body, and the temperature of the catalyst body becomes lower than that of the inside by the fluid that passes through the inside. And because the temperature of the catalyst as a whole is low,
As described above, the deterioration of the catalyst life and the ignition are less likely to occur. Of course, if the temperature becomes too low, the catalyst becomes inactive and incompletely burns, so the amount of the cooling fluid is set to maintain a predetermined temperature.

Embodiment An embodiment of the present invention will be described below with reference to FIG. 6
Is a catalyst, which is made of heat-resistant material such as alumina, silica, and calcia. The catalyst body 1 is provided with a large number of combustion holes 7. An air and fuel gas supply unit (not shown) is provided upstream of the premixing pipe 8.
Then, the mixed gas that has entered the premix gas chamber 9 through the premix pipe 8 is burned by the platinum group-based catalyst carried on the surface of the catalyst body 6. Further, in order to sufficiently carry out such a reaction of the catalyst, the catalyst body 6 is preliminarily heated by the heater 10 to a predetermined temperature. The catalyst body 6 is a heat insulating material 11.
It is kept on the inner wall 12 of glass or the like forming the premixing chamber 9 via.

In such a structure, the blower 1 for cooling is used in the present invention.
3, an inner cooling path 14 which is connected to the discharge port of the blower 13 through an external cooling path to be described below, and has the other end which penetrates the catalyst body 6 and is formed in a tubular shape by iron or stainless steel, and the inner wall 12. An outer cooling path 15 is provided so as to surround the inner wall 12 so as to cool the outer periphery thereof, and a part of which is formed of a wall of glass or the like connected to the discharge port of the blower 13. The operation of these two cooling paths will be described below.

The premixed gas starts burning from the upstream surface of the catalyst body 6 and finishes its reaction in the combustion holes 7 while reaching the downstream surface. A feature of such catalytic combustion is that a large proportion of the combustion heat heats the catalyst body 6, so that the temperature of the catalyst body 6 tends to rise. Therefore, as described above, there is a limit in increasing combustion with the small size medium contact member 6. Although the heat of the catalyst body 6 is diffused by radiation, the heat cannot be sufficiently radiated just by using glass on the inner wall of the premix chamber 9 as in the conventional case. The reason for this is that most of the heat does not pass through the glass, but the glass itself absorbs it and the temperature of the glass rises. Since the glass heated to a high temperature does not sufficiently absorb the heat of the catalyst body, the heat of the catalyst body is not sufficiently dissipated and the temperature tends to rise.

However, in the configuration of the present invention, since the internal cooling path 14 penetrating the inside of the catalyst body 6 receives the heat radiated by the catalyst body 6 in the entire path, the temperature of the catalyst body 6 is unlikely to rise, and the external cooling path The inner wall 12 cooled by 15 also prevents the temperature rise of the catalyst body 6. Of course, in this case, the catalyst 6 is slightly cooled by the heat conduction through the heat insulating material 11 interposed between the catalyst 6 and the inner wall 12 and the internal cooling path 14, but the cooling by the heat conduction is also performed. Is not preferable because only the contact portion has a low temperature and the temperature of the catalyst body 6 becomes non-uniform. Asbestos ceramic fibers and mineral fiber-based materials are selected for this purpose. That is, the present invention aims to uniformly reduce the temperature of the catalyst surface by cooling by radiation, and cooling by heat transfer is localized, so the internal cooling path 1
4 and the catalyst body 6 are insulated. Further, in the above-mentioned embodiment, both the outside and the inside are cooled, but when the size of the catalyst body 6 is narrow, either one may be used. When the size of the catalyst body 6 is wide, temperature unevenness occurs due to the difference in the distance between each part of the catalyst body 6 and the cooling path, and a partial increase in temperature occurs. In this case, an internal cooling path may be provided and the number thereof may be arbitrarily selected.

A heat absorption process is performed on the inner wall 12 that receives the heat of the catalyst body 6 and the heat receiving surface of the internal cooling path 14, that is, the portion that faces the catalyst body 6. Heat absorption treatment is sandblasting for metal,
Oxide film treatment, black coating, thermal spraying, etc. are performed to obtain a surface with better heat absorption rate than metallic materials. If the absorption rate (also called emissivity) is low, the heat is reflected and the temperature of the catalyst body 6 becomes high. Even if the combustion amount per unit area is increased by adding the invention of the second aspect, ignition or high temperature deterioration of the catalyst can be prevented.

Next, a different embodiment will be described with reference to FIG. It should be noted that the same parts as those of the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted. A large number of fins 16 for heat dissipation are provided on the heat dissipation part of the inner wall 12 of the premix air chamber 9 and the heat dissipation part of the internal cooling path 14, that is, on the cooling fluid side of both. As the temperature difference between the catalyst body 6 and the inner wall 12 or the internal cooling passage 14 is larger, the radiation amount of the catalyst body 6 is increased and the temperature is lowered. For this purpose, fins are provided on both heat dissipation portions. The effect of the present invention is further enhanced by adding this invention.

Next, claim 2 will be described.

It is well known that when a platinum group platinum, palladium or the like is supported as a catalyst, the platinum group has an extremely high activity as a combustion catalyst having an effect of suppressing ignition. However, it not only actively activates the oxidation reaction but also has a function of suppressing ignition. That is, a combustible air-fuel mixture is supplied to the premixed air chamber 9, but if the temperature of the catalyst body 6 becomes high, the aforementioned air-fuel mixture will ignite. However, in this case, even if the mediator reaches the ignition temperature of the air-fuel mixture, it does not ignite. This seemingly mysterious phenomenon is because the temperature of the air-fuel mixture itself is not high because the air-fuel mixture flows toward the catalyst body 6. However, also in this case, it is considered that the extremely thin layer of the air-fuel mixture contacting the catalyst body 6 has reached the ignition temperature.
Since this layer is microscopically small and does not grow as a flame, the flame does not spread to the entire premixed gas chamber 9 as ignition. However, if the temperature of the catalyst body 6 becomes extremely high, this microscopic layer becomes thick and the premixed gas chamber 9 is ignited. In order to suppress this phenomenon, it is necessary to devise to lower the temperature of the catalyst body 6, but if a catalyst of the platinum group is used as the catalyst, it has a great function of suppressing ignition even at high temperatures. This phenomenon is extremely strong with platinum group catalysts,
Since a reaction zone is formed very close to platinum, it is said that even if a flame grows, it is difficult to grow by touching platinum. If such a platinum group catalyst is used, the amount of combustion can be increased and the temperature can be raised because the ignition is suppressed.

EFFECTS OF THE INVENTION As described above, according to the present invention, since it is possible to prevent the temperature of the combustion surface of catalytic combustion from being overheated, it is possible to realize a high load of catalytic combustion, which enables a combustion apparatus with a small size and a large calorific value. Become. This combustion device also retains the cleanliness, such as low NO _x, which is an original feature of catalytic combustion. Further, such a combustion device can be used for heating by using air as a fluid in the above-mentioned cooling path or for hot water supply by using water, and also has a function as a heat exchanger. It is also a thing.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of another embodiment of the present invention, and FIG. 3 is a sectional view of a conventional combustion apparatus. 6 ... Catalyst, 11 ... Insulating material, 14 ... Internal cooling path, 15 ... External cooling path, 16 ... Radiating fin.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nora Ono 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masato Hosaka, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) References Actual development Sho 59-175839 (JP, U) Actual development Sho 58-42520 (JP, U)

Claims (2)

[Claims] 1. A catalyst body having a large number of combustion holes, a portion for supplying a mixture of fuel and combustion air to the catalyst body, and a catalyst body and a heat insulating portion, which are provided on the outer circumference or inside of the catalyst body. A combustion apparatus having a cooling path, and performing radiation absorption surface treatment on a surface of the cooling path facing the catalyst body. 2. The combustion apparatus according to claim 1, wherein the catalyst supported on the catalyst body is a platinum group type catalyst.