JPH05346214A - Combustion device - Google Patents

Abstract

PURPOSE:To reduce incomplete combustion in low-NOx combustion and expand the variable width of combustion rate. CONSTITUTION:There are provided a burner body 2 including a first burner port 1 and a first fuel-air mixture chamber 3 in communication therewith, a blowoff plate 13 wherein a plurality of the bodies 2 are parallelly disposed and second burner ports 15 are provided between each of the bodies 2 and between the bodies 2 and combustion chamber walls at either ends of a combustion chamber, a second fuel-air mixture chamber 16 defined by the bodies 2 and the plate 13, an air intake part 21 provided in the chamber 16, and fuel-air mixture passages 7 provided for the burner bodies 2 so as to connect the chambers 3 with the chambers 16, wherein a thin flame (A), a discontinuous face of a flame, is surrounded by a thick flame (B). As a result, low-NOx combustion can be provided and further the discontinuous face of a thin flame which tends to generate incomplete combustion is stabilized by a thick flame, preventing thereby incomplete combustion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly applied to a burner with low NO.
The present invention relates to a combustion device that prevents x and incomplete combustion.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a household burner of this type has a first air-fuel mixture chamber 3 provided in a burner body 2 having a first flame mouth portion 1 and a first air-fuel mixture. A second air-fuel mixture chamber 6 having a second flame port portion 5 constituted by wall plates 4 on both sides of the chamber 3, and a burner for communicating the first air-fuel mixture chamber 3 and the second air-fuel mixture chamber 6 with each other. The air-fuel mixture passage 7 provided in the main body 2, the flame holding plate 8 that is provided between the first flame opening portion 1 and the second flame opening portion 5 to stabilize the flame base portion, and the An air intake 9 for setting the primary air ratio of the air-fuel mixture chamber 6 is provided. A large number of burner main bodies 2 having such a structure were housed inside the burner case 10 with the wall plates 4 in contact with each other. Reference numeral 11 is a fuel switching valve.

In the combustion apparatus having the above structure, the nozzle 1
2 discharges gas into the first air-fuel mixture chamber 3, while the fan 2
Combustion air sent from No. 0 mixes with the above-mentioned gas and is jetted from the first flame nozzle portion 1 and burned. Further, a part of the mixed gas enters the second mixed gas chamber 6 through the mixed gas passage 7, is further mixed with the combustion air introduced through the air intake port 9 and is ejected from the second flame mouth portion 5, It is ignited by the flame of the first flame mouth 7.
As a result, a stable rich flame with a low oxygen concentration is formed on the first flame port 1. Further, a large amount of air from the air intake port 9 and a mixture of gas and combustion air supplied from the mixture passage 7 become a lean mixture inside the second mixture chamber 6, and the mixture is discharged from the second flame mouth portion 5. It spilled out and burned due to the thermal influence of the rich flame, forming a lean flame with a high oxygen concentration. The rich flame and the lean flame have their flame bases stabilized by the effect of a small vortex formed on the flame holding plate 8.
A lean flame having a low NOx concentration and an unstable characteristic is stabilized by a rich flame to realize rich flame combustion as a whole to reduce the generation of NOx.

[0004]

However, the above-mentioned conventional structure is satisfactory in the effect of preventing incomplete combustion and reducing NOx when all the burners are burning, but To expand the variable range,
When the number of burning burners is switched by the fuel switching valve 11, the lean flame between the burning burners and the unburned burners is easily blown off by the air ejected from the unburned burners. There was a problem of generating complete combustion.

The present invention is intended to solve the above problems, and aims to reduce incomplete combustion, achieve both low NOx and almost complete combustion, and increase TDR.

[0006]

In order to achieve the above object, the present invention provides a burner body having a first flame opening portion and a first air-fuel mixture chamber communicating with the first flame opening portion, and a plurality of burner bodies arranged in parallel. ,
An injection plate having a second flame opening provided between the burner bodies and between the burner body and the combustion chamber walls at both ends of the combustion chamber; A second air-fuel mixture chamber, an air intake portion provided in the second air-fuel mixture chamber, a first air-fuel mixture chamber and a second air-fuel mixture chamber and a mixture passage provided in the burner body, The mixture passage is provided only on one side surface on the same side of each burner body.

[0007]

According to the present invention, according to the above structure, a part of the rich air-fuel mixture in the first air-fuel mixture chamber flows into the second air-fuel mixture chamber through the air-fuel mixture passage on only one side surface of the burner body in the same direction. The air-fuel mixture is mixed with the air from the inlet, and the lean air-fuel mixture is ejected as the lean air-fuel mixture from the second flame mouth portion. The fuel from the adjacent burner body is similarly supplied to the other second air-fuel mixture chamber on both sides of the burner body. Therefore, the state of the flame formed in the combustion chamber is a lean flame, a rich flame, and a lean flame repeated from the combustion chamber wall as viewed from above the combustion chamber, and finally a lean flame, a rich flame, an air layer, and a combustion chamber wall. The lean air-fuel mixture is ignited by being thermally influenced by the rich flame formed on the first flame mouth portion, and performs lean combustion having a characteristic of low NOx. The lean flame still contains a large amount of oxygen even after combustion, and the rich flame becomes smaller by being supplied to the adjacent rich flame, so that the heavy flame is burned under high load. One end of the combustion part, which is a discontinuity of the flame, ends with a lean flame and the combustion is likely to be incomplete, but the lean flame is surrounded by the combustion chamber wall and cut off from the air layer to improve the combustibility. The other discontinuous surface ends with a rich flame and air is supplied to improve the combustibility.

Further, when switching the number of burners that are burning in order to widen the variable range of combustion amount, air is drawn from the second flame port between the burners that are burning and the burners that are not burning. The state of the flame seen from the upper part of the combustion chamber becomes a rich flame, a rich flame, and a lean flame from the combustion chamber wall in the order of the rich flame and the air layer. Therefore, similar to the above case where the entire burner is in the burning state, incomplete combustion does not occur from the discontinuous surface of the flame.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. The same components as those in FIG. 3 are designated by the same reference numerals. 1 and 2, reference numeral 2 denotes a burner body that encloses the first air-fuel mixture chamber 3, and the burner body 2 has an upper surface provided with a first flame opening 1 having a large number of slits.
On one side surface of each burner body 2 in the same direction, that is, on the right side surface in this embodiment, a plurality of air-fuel mixture passages 7 are provided at optimum intervals in the longitudinal direction. In addition, a support tool 12 is provided on each side of the burner body 2.
Is attached, and the end portion of the injection plate 13 is inserted into a groove formed by the support tool 12 and the burner body 2, and the adjacent burner bodies 2 are joined and integrated. The injection plate 13 is formed by bending a flat plate into a mountain shape, and has a second flame port portion 15 including a large number of ejection ports 14 in the inclined portion. Surrounded by the injection plate 13 between adjacent burner main bodies 2,
The space on the downstream side of the air-fuel mixture passage 7 serves as a second air-fuel mixture chamber 16. A throat portion 17 is formed on the upstream side of the burner main body 2, and a plurality of such burner main bodies 2 are arranged side by side to form a burner block and are housed inside the burner case 10. The burner case 10 is provided with a fuel pipe 19 provided with a nozzle 18 that ejects fuel facing each throat portion 17, and a fan 20. Reference numeral 21 is an air intake portion formed between the burner main bodies. Reference numeral 11 is a fuel switching valve.

In the above structure, a part of the combustion air supplied from the fan 20 flows into the burner main body 2 from the throat portion 17, and most of the remaining air flows between the burner main body 2 and the burner case. 10 and the burner body 2, and is supplied to the respective second air-fuel mixture chambers 16. On the other hand, the fuel supplied from the fuel pipe 19 is ejected from each nozzle 18 toward each throat portion 17, and the burner body 2
And is mixed with the combustion air, and is supplied to the first air-fuel mixture chamber 3. The air-fuel mixture in the first air-fuel mixture chamber 3 has a primary air ratio of 30 to 60%. A part of this air-fuel mixture blows out from the first flame mouth portion 1 to form a rich flame, and most of the remaining air-fuel mixture is on the right side of each burner body 2 from the air-fuel mixture passage 7 on the right side of each burner body 2. Is introduced into the second air-fuel mixture chamber 16 and is mixed with a large amount of air coming from the air intake portion 21. At this time, set the primary air ratio to 1
After becoming a lean air-fuel mixture of about 70 to 250% and homogenized, it is directed from the jet port 14 provided in the inclined portion of the second flame port 15 toward the left and right first flame ports 1. Is inclined and ejected. Therefore, the state of the flame formed in the combustion chamber is that the lean flame (A), the rich flame (B), and the lean flame (A) are repeated from the combustion chamber wall on the right side of the combustion chamber, and finally the lean flame (A) and the rich flame. (B), air layer (C), combustion chamber wall. Here, the characteristics of the lean flame and NOx will be described.
The generation amount of thermal NOx decreases as the temperature of the combustion reaction zone decreases. Therefore, it is well known that the leaner the air-fuel mixture containing a large amount of air, the higher the heat capacity, the lower the flame temperature, and the lower the NOx.

On the other hand, the leaner the air-fuel mixture becomes, the more unstable the flame becomes, and finally the flame blows off and incomplete combustion occurs.

Therefore, in the above structure, in the continuous surface of the flame which occupies most of the flame, the ambient temperature of the lean air-fuel mixture is raised by the thermal action of the rich flame formed on the first flame mouth portion 1, and By providing the two flame openings 15 on the inclined portion to increase the flame opening area and reduce the flow velocity of the lean air-fuel mixture, the lean air-fuel mixture can be completely burned. In addition, incomplete combustion is prevented by the following mechanism at both ends of the combustion part, which is the discontinuity surface of the flame. The right side of the combustion chamber ends with a lean flame (A) and the combustion is likely to be incomplete, but the lean flame is surrounded by the burner case 10 and cut off from the air layer to improve the combustibility. The discontinuous surface on the left side of the combustion chamber ends with rich flame (B), and air is supplied to improve the combustibility.

Further, when the number of burning burners is switched in order to widen the variable range of the combustion amount, the fuel switching valve 11 is shut off and the fuel is supplied only to the right burner. Therefore, since the air-fuel mixture passage 7 is provided on the right side surface of each burner body 2, the lean air-fuel mixture is provided inside the right-hand side secondary air-fuel mixture chamber 16 among the secondary air-fuel mixture chambers 16 on both sides of the burner body 2. Air is supplied to the inside of the left side secondary air-fuel mixture chamber 16, and the state of the flame formed in the combustion chamber is as shown in FIG. 3 from the lean combustion flame (A) from the combustion chamber wall on the right side of the combustion chamber. , Rich flame (B), air layer (C), and combustion chamber wall. In other words, the switching part between the burner that burns and the burner that does not burn becomes a rich flame, an air layer and the entire burner is in the same burning state. Incomplete combustion occurs from the discontinuous surface of the flame as above. There is no such thing.

[0014]

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

1) In all burners, the state of the flame formed in the combustion chamber by providing the air-fuel mixture passage on only one side surface on the same side of the burner body is such that lean flame, rich flame and lean flame are repeated from the combustion chamber wall. At the end, it becomes a lean flame, rich flame, air layer, and combustion chamber wall. The discontinuous surface of the lean flame, which is prone to incomplete combustion, is surrounded by the wall of the combustion chamber on one side to shut off the air and eliminate the blow-off of the lean flame to achieve complete combustion. The complete combustion is promoted by the effective combustion promoting effect, and the incomplete combustion of the combustion device can be prevented.

2) When the number of burning burners is changed in order to widen the variable range of the burning amount, air is blown between the burning burners and the unburned burners from the second flame port. The state of the flame formed in the combustion chamber by being jetted is a lean flame, a rich flame, and a lean flame from the wall of the combustion chamber in the order of the rich flame and an air layer. Therefore, in the same manner as above where the entire burner is burning, incomplete combustion does not occur from the discontinuous surface of the flame, the incomplete combustion of the combustion device can be prevented, and the variable range of the combustion amount (TD
R) can be expanded.

3) NOx reduction can be realized by burning most of the fuel with a lean flame having a low flame temperature formed on the second flame port. Further, since the lean air-fuel mixture is inclined and jetted and supplied to the rich flame, the combustion gas containing a large amount of oxygen is compulsorily supplied to the rich flame after combustion, so that the flame length is shortened and the combustion apparatus can be downsized.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a combustion device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the main part of the device.

FIG. 3 is a partial cross-sectional view of the device when the fuel switching valve is operating.

FIG. 4 is a partial sectional view of a conventional combustion device.

[Explanation of symbols]

 1 First Flame Port 2 Burner Body 3 First Mixture Chamber 7 Mixture Passage 13 Injection Plate 15 Second Flame Mouth 16 Second Mixture Chamber 21 Air Intake

Claims (1)

[Claims] 1. A burner body having a first flame opening portion and a first air-fuel mixture chamber communicating with the first flame opening portion, a plurality of the burner bodies are arranged in parallel, and between the respective burner bodies and between the burner bodies. An injection plate having a second flame opening provided between the combustion chamber walls at both ends of the combustion chamber, a second mixture chamber formed by being surrounded by the burner body and the injection plate, and An air intake portion provided in the second mixture chamber, and a mixture passage provided in the burner body for communicating the first mixture chamber and the second mixture chamber with each other, the mixture passage A combustion device provided only on one side surface on the same side of each burner body.