JPH06123409A - Combustion equipment - Google Patents

Abstract

PURPOSE:To attain low NOx combustion, to make combustion equipment small in size, to reduce combustion noise and to enlarge variableness of a combustion amount. CONSTITUTION:This equipment is made to have a construction wherein a horizontal part 13 is provided on the opposite side parts of a burner main body 2 having a first port part 1, a vertical part 14 on the downstream side and an injection plate 12 constructed by bending sequentially a slant part 16 having a second port part 18 comprising a number of small holes, at a rim part, and these parts and plate are made to be in close contact with these parts and side to be integrated. A fuel-air mixture passes through a mixture passage 7 of the burner main body 2 and is supplied from a first mixture chamber 3 to a second mixture chamber 20 to which a large quantity of air is supplied, so that a thick and thin fuel combustion be attained. According to this constitution, a thick flame is formed at the first port part 1, while a thin flame is formed at the second port part 18, and thereby the thick and thin fuel combustion of low NOx is realized. Besides, the thin mixture and the thick flame are separated to be independent of each other by the vertical part 14 and held and stabilized at the rim part and the horizontal part 13 respectively and thereby noise is made low. At the same time, a back fire into the second mixture chamber 20 is prevented by the small holes, thermal deformation is held back by the rim part and thus TDR is enlarged.

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 designed to achieve x and low noise.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, 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 formed by wall plates 4 on both sides of the chamber 3, and a burner connecting 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 for stabilizing the flame base between the first flame mouth portion 1 and the second flame mouth portion 5, and the second air-fuel mixture on the wall plate 4. And an air intake 9 for setting the primary air ratio of the chamber 6. A large number of burner main bodies 2 having such a configuration were housed inside the burner case 10 with the wall plates 4 in contact with each other.

In the combustion apparatus having the above construction, a stable rich flame having 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 the air-fuel mixture supplied from the air-fuel mixture passage 7 become a lean air-fuel mixture outside the flammability limit inside the second air-fuel mixture chamber 6, and flow out from the second flame mouth portion 5. And burned by being affected by the heat of a rich flame,
It formed a lean flame with 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 stabilizing plate 8, and the lean flame having an unstable property with low NOx concentration is stabilized by the rich flame, As a result, dark and light combustion was realized to reduce the generation of NOx.

[0004]

However, although the above-mentioned conventional structure is satisfactory in terms of the effect of reducing NOx, as the combustion amount is reduced, the first flame opening portion 1 and the second flame opening portion are reduced. When the air-fuel mixture jetting speed from the portion 5 decreases and especially when the supplied air amount decreases, the air-fuel mixture inside the second air-fuel mixture chamber 6 diluted to outside the flammable range in order to reduce NOx is generated. There was a problem in that the lean flame entered the combustible range, flashed back to the outlet of the mixture passage 7 via the second flame opening 5, and abnormally heated the burner body 2 and the wall plate 4. . Furthermore, since the upper end surfaces of the wall plates 4 that are in contact with each other are not fixed, they are easily deformed, and a gap is generated between the adjacent wall plates 4 so that the amount of secondary air inside the second air-fuel mixture chamber 6 is small. There was a problem that became. Further, there is a combustion device as shown in Japanese Patent Publication No. 63-8363 which has a similar shape, but this is mainly intended for downsizing as a combustion device and does not reduce NOx.

The present invention solves the above-mentioned problems and provides a low N
Compatibility of Ox and high-load combustion, expansion of TDR by prevention of flashback to the mixture passage outlet of lean flame, prevention of burner deformation,
Furthermore, the purpose is to reduce noise by stabilizing the flame.

[0006]

In order to achieve the above object, the present invention has a burner body having a first flame opening, a first air-fuel mixture chamber provided in the burner body, and a plurality of burner bodies. An injection plate that connects the burner bodies, a second air-fuel mixture chamber surrounded by the burner body and the injection plate, a first air-fuel mixture chamber and a second air-fuel mixture chamber. The burner body is provided with a mixture passage provided in communication with the burner body, and the injection plate has a horizontal portion provided along the lateral side of the upper surface of the first flame opening portion, a vertical portion downstream of the horizontal portion, and a rim portion. The structure is such that the injection plate is bent and integrally formed in the order of the inclined portion, and the inclined portion is provided with the second flame port portion having a large number of small openings.

[0007]

According to the present invention, the lean air-fuel mixture outside the flammable range is obliquely ejected from the small opening provided on the inclined portion of the second flame opening portion by the above-mentioned configuration, and is formed on the first flame opening portion. It is ignited by the thermal influence of the rich flame and has low NOx.
It forms a lean flame with the characteristics of. A lean flame has an inherently unstable characteristic, but due to the thermal effect of a nearby rich flame,
The rim retains the flame base and stabilizes it. The lean flame still contains a large amount of oxygen even after combustion, and when it is forcibly supplied to the rich flame, the flame becomes smaller and burns at high load. Further, when the combustion amount becomes small or the supply air amount decreases, the air-fuel mixture in the low-speed combustible range is jetted from the second flame port. At this time, since the second flame mouth portion is composed of a large number of small mouths, the lean flame does not backfire to the inside of the second air-fuel mixture chamber and a flame is formed on the small mouth. In addition, a small circulation area of the air-fuel mixture is formed in the horizontal portion, and exhibits a flame holding function. The lean flame is retained in the rim portion and the rich flame is retained in the horizontal portion, and the flame retaining positions are separated and independent in the vertical portion, so even if a temporary instability factor due to disturbance etc. occurs, it will be affected by the interaction. There is no amplification of instability, and stable low noise density combustion is always performed. Further, since the injection plate integrally connects the adjacent burner main bodies, no gap is generated, and the rim portion at the boundary of the inclined portion which becomes hot acts as a rim for preventing deformation.

[0008]

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 main body that encloses the first air-fuel mixture chamber 3, and the burner main body 2 has an upper surface on which a first flame opening 1 having a large number of slits is formed. Air-fuel mixture passages 7 are provided on both side surfaces of the burner body 2 at optimum intervals in the longitudinal direction. Supports 1 are provided on both sides of the burner body 2.
1 is attached, and the lower end portion of the injection plate 12 is inserted into a groove formed by the support tool 11 and the burner body 2, and the adjacent burner bodies 2 are joined and integrated. The injection plate 12 is formed by bending a flat plate, and includes a horizontal portion 13 along the side of the first flame nozzle portion 1, and a vertical portion 14, a rim portion 15, and an inclined portion 16 in the downstream direction of the horizontal portion 13. And is sequentially bent. The inclined portion 16 is provided with a second flame mouth portion 18 composed of a large number of small openings 17 having a diameter smaller than the fire extinguishing diameter. An inverted mountain-shaped mixing plate 19 is provided on the downstream side of the air-fuel mixture passage 7 between the burner body 2 and the injection plate 12, and the space on the downstream side serves as a second air-fuel mixture chamber 20. A throat portion 21 is provided on the upstream side of the burner main body 2, and a dividing plate 23 having a dividing port 22 is inserted in the downstream side main body to make the downstream side space the first mixture chamber 3. 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 26 provided with a nozzle 25 for ejecting fuel facing each throat portion 21 and a fan 24.

In the above structure, a part of the combustion air supplied from the fan 24 flows into the inside of the burner main body 2 from the throat portion 21, and most of the remaining air flows between the burner main body 2. On the other hand, the fuel supplied from the fuel pipe 23 is ejected from each nozzle 22 toward each throat portion 21, flows into the burner main body 2 and is uniformly mixed, and the primary air ratio is set to 30 to 60%. The resulting mixture is A part of this air-fuel mixture passes through the division ports 22 of the division plate 23 and is supplied to the first air-fuel mixture chamber 3, where it is ejected from the first flame mouth portion 1 to form a rich flame. Most of the remaining air-fuel mixture is ejected from the air-fuel mixture passage 7, and is evenly mixed with a large amount of air entering between the burner main bodies 2 by the mixing plate 19 to become a lean air-fuel mixture and becomes the second air-fuel mixture chamber. 20. At this time, the primary air ratio is about 170 to 250%, and the mixture becomes a lean mixture outside the flammable range, and is jetted while being inclined from the small port 17 provided in the inclined portion 16 of the second flame port 18.
The lean air-fuel mixture is ignited by being thermally influenced by the rich flame formed on the first flame mouth portion 1, and the rim portion 15 holds the base portion to perform a stable lean combustion. The lean flame still contains a large amount of oxygen even after combustion, and is forcibly injected and supplied to the rich flame to accelerate the combustion reaction and reduce the flame to realize high-load combustion. Here, the amount of thermal NOx generated decreases as the temperature of the combustion reaction zone is lower. Therefore, it is well known that the leaner the air-fuel mixture containing a large amount of air, the more the heat capacity increases, the flame temperature decreases, and the NOx can be reduced. The rich flame formed on the first flame mouth part 1 is stabilized by the flame holding effect of the small vortex formed on the horizontal portion 13, and the vertical portion 14 guarantees the flame holding effect of the lean flame. Since the flame holding positions of the part 15 and each other are separated and independent, amplification of instability due to interaction is eliminated even if a temporary instability factor due to disturbance or the like occurs. Therefore, it is possible to suppress an increase in combustion noise and realize low NOx combustion in the entire burner block.

Further, when the amount of combustion becomes small, the jetting flow velocity of the air-fuel mixture in the first flame opening portion 1 and the second flame opening portion 18 becomes small, and the flame approaches the respective flame opening portions.
Further, when the supply air amount fluctuates, the combustion amount is small, so that the air-fuel mixture inside the second air-fuel mixture chamber 20 may fall into the flammable range. At this time, the lean flame tries to propagate into the second air-fuel mixture chamber 20, but since the small opening 17 has a hole diameter smaller than the extinction diameter, the flame is reversed inside the second air-fuel mixture chamber 20. Prevent fire. Therefore, stable combustion can be obtained even if the combustion amount is reduced, and the TDR can be set large. Further, at this time, the temperature of the inclined portion 16 having the small edge 17 easily rises, but the rim portion 15 continuous to the inclined portion 16 acts as a reinforcing portion for preventing deformation, so that thermal deformation of the injection plate 12 is suppressed.

Further, the injection plate 12 is a plate material which is integrally molded and bent, and is inserted into a gap formed between the support tool 11 and the burner main body 2 so that the vertical wall of the injection plate 12 and the wall portion of the burner main body 2 are mutually connected. Since the burner blocks are joined in close contact with each other, the rigidity of the burner block as a whole is increased and no deformation occurs. Therefore, it is possible to reduce variations in the mixing ratio of the second air-fuel mixture chamber 20 due to the occurrence of gaps that cannot be controlled by design, and it is possible to stabilize the performance.

[0012]

As described above, according to the combustion apparatus of the present invention, the following effects can be obtained. 1) The 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. Also, since the lean air-fuel mixture is inclined and ejected and supplied in the direction of the rich flame, the combustion gas containing a large amount of oxygen is forcibly supplied to the rich flame after combustion, which shortens the flame length and realizes downsizing of the combustion device. it can. 2) The originally unstable lean flame is stabilized by the flame base of the rim and the thermal combustion promotion effect of the rich flame formed on the first flame mouth, which stabilizes the flame. Stable combustion can be performed due to the flame holding effect of the small vortex formed in the. Also, since the rim and horizontal parts are separated by the vertical part and the flame holding positions are independent of each other, even if a temporary instability factor occurs due to disturbance etc., the instability due to the interaction is not amplified and it is always stable. Since dark and light combustion is realized, combustion noise can be reduced. Furthermore, since the second flame port is provided on the inclined surface of the injection plate, it is possible to set a large opening area, the ventilation resistance is reduced accordingly, and the fan rotation speed can be reduced, further reducing the noise of the device. Can be planned. 3) Since the second flame mouth is provided with a small diameter smaller than the extinction diameter, even if the combustion amount becomes small and the flame approaches the second flame mouth, the second mixture chamber will It is possible to prevent the flame from flashing back into the air-fuel mixture passage therethrough, so that the variable range (TDR) of the combustion amount can be expanded. 4) A horizontal portion, a vertical portion, a rim portion, an inclined portion forming the second flame mouth portion, etc. are integrally formed on the injection plate, and a second air-fuel mixture chamber is formed between the burner body and the injection plate. Because you can
The number of parts is reduced and it can be manufactured at low cost. 5) The sloping part with a small edge suppresses thermal deformation of the injection plate by the rim part acting as a reinforcement part for preventing deformation, and since the burner main bodies are joined together by the injection plate to be integrated, the overall burner block is rigid. Since there is no further deformation and there is no gap through which the secondary air leaks, variations in the mixing ratio of the second air-fuel mixture chamber can be reduced, and performance can be stabilized and reliability can be improved.

[Brief description of drawings]

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

FIG. 2 is a partial cross-sectional view of the main part of the device.

FIG. 3 is a partial sectional view of a conventional combustion device.

[Explanation of symbols]

 1 First Flame Mouth 2 Burner Main Body 3 First Mixture Chamber 7 Mixture Passage 12 Injection Plate 13 Horizontal Part 14 Vertical Part 15 Rim Part 16 Inclined Part 17 Small Mouth 18 Second Flame Mouth Part 20 Second Mixing Air chamber

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoichi Kimura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A burner body having a first flame mouth portion in which rich flame is generated, and a first air-fuel mixture chamber provided in the burner body,
A plurality of the burner bodies are arranged side by side, both ends of the respective burner bodies are joined to each other, and an injection plate is provided therebetween, and a second air-fuel mixture chamber formed by being surrounded by the burner body and the injection plate. And a mixture passage provided in the burner body, which communicates the first mixture chamber with the second mixture chamber,
The injection plate has a horizontal portion extending laterally of the first flame mouth portion, and a vertical portion, a rim portion, and an inclined portion that are formed in the downstream direction of the horizontal portion and are integrally formed by sequentially bending the injection plate. Combustion having a second flame mouth portion in which the lean flame is formed in the inclined portion, which is composed of a number of small orifices having a diameter smaller than the extinguishing diameter ejected in an oblique direction with respect to the injection direction of the first flame orifice portion. apparatus.