JP3196398B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low NOx combustion apparatus used for a water heater or a heater for burning a gas obtained by evaporating gas and oil.

[0002]

2. Description of the Related Art Conventionally, this kind of low NOx combustion apparatus is shown in FIG.
As shown in FIG. 2, a plurality of burner main bodies 3 including a first air-fuel mixture chamber 2 communicating with a flame outlet 1 are provided in parallel in a combustion chamber 4, and between adjacent burner main bodies 3, and between burner main bodies 3. 3
An injection plate 5 is provided between the fuel cell and the combustion chamber 4. Reference numeral 6 denotes a second air-fuel mixture chamber formed by being surrounded by the burner main body 3 and the ejection plate 5, 7 denotes an air intake port communicating with the second air-fuel mixture chamber 6, 8
Is a flame holding plate for stabilizing the flame base. Reference numeral 9 denotes a mixture passage which connects the first mixture chamber 2 and the second mixture chamber 6. Reference numeral 10 denotes a fan for supplying combustion air, and reference numeral 11 denotes a fuel passage provided with a nozzle 12 corresponding to the burner main body 3, and a part of the fuel passage 11 can be shut off by a fuel switching valve 13.

In the combustion apparatus having the above-described structure, after the fuel discharged from the nozzle 12 to the first air-fuel mixture chamber 2 mixes with the combustion air sent from the fan 10 in the first air-fuel mixture chamber 2,
The fuel is ejected from the flame opening 1 and burns to form a stable rich flame having a low oxygen concentration. A part of the fuel enters the second mixture chamber 6 from the mixture passage 9 and is further mixed with a large amount of combustion air sent from the air intake 7 to become a lean mixture, which is ejected from the ejection plate 5. It burns under the thermal influence of the rich flame formed on the flame opening 1 to form a lean flame having a low NOx concentration.

[0004] The rich flame and the lean flame have their flame base stabilized by the effect of a small vortex formed on the flame holding plate 8.
A specific lean flame having a low NOx concentration is stabilized by a rich flame, and a lean burn is realized as a whole to reduce the generation of NOx.

[0005]

However, in the above-mentioned conventional structure, incomplete combustion is prevented when all the burners are burning, and the effect of reducing NOx is satisfactory. When the number of burning burners is switched by the fuel switching valve 13 in order to widen the variable range of the combustion amount, the lean flame which is the boundary between the burning burner and the non-burning burner has half the fuel supply. In addition, there is a problem that the air becomes excessive and the air blown out from the burner portion 1 of the burner that is not burning easily blows off, causing incomplete combustion and further increasing noise.

The present invention has been made to solve the above-mentioned problem, and enhances the stability of a flame when the number of burners is switched, thereby achieving a low N.
The purpose is to realize Ox, complete combustion and low noise, and to expand TDR.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a flame outlet for discharging a fuel-rich rich mixture of fuel and combustion air, and a communication with the flame outlet. And a burner body including the first air-fuel mixture chamber, and a plurality of the burner bodies provided side by side, between the adjacent burner bodies, and at an upper portion provided between the burner body and the combustion chamber walls at both ends of the combustion chamber. An injection plate having a large number of injection ports having a steep mountain shape, a second air-fuel mixture chamber formed by being surrounded by the burner body and the injection plate, and provided in the second air-fuel mixture chamber An air intake unit, a fuel passage for supplying fuel to the burner main body, and a fuel switching valve for shutting off a part of the fuel passage are provided, and the first mixture chamber and the second mixture chamber communicate with each other. The mixture passage is defined as a boundary of a combustion region when a part of the fuel passage is shut off. Not provided in the burner main body facing said second air-fuel mixture chamber against, the said burner body facing the other second mixture chamber is obtained with the mixture channel.

According to a second aspect of the present invention, in addition to the first aspect, when a part of the fuel passage is shut off, an injection for forming a second mixture chamber facing a boundary of a combustion region is provided. The plate has a planar shape and is provided with a spout in the vertical direction.

[0009]

According to the present invention, by means of the above means, a fuel-rich rich mixture of fuel and primary air for combustion is ejected from the flame opening, and the first mixture is ejected from the ejection port of the injection plate. Part of the rich air-fuel mixture in the air chamber passes through the air-fuel mixture passage provided in the burner main body, flows into the second air-fuel mixture chamber, and the lean air-fuel mixture mixed with the air flowing in from the air intake is ejected. Further, when a part of the fuel passage is shut off, only the air that has flowed in from the air intake portion is jetted from the jet port of the jet plate facing the second mixture chamber facing the boundary of the combustion region. Therefore, the state of the flame formed in the combustion chamber is such that an air layer is formed after a repetition of a lean flame, a rich flame, a lean flame, and a rich flame when viewed from the upper part of the combustion chamber, and further a repetition of a rich flame and a lean flame. The lean mixture is ignited by being thermally affected by the rich flame formed on the flame opening, and performs lean combustion having low NOx characteristics. The lean flame still contains a large amount of oxygen even after combustion, and the rich flame burns at a high load when mixed with the adjacent rich flame. Further, the rich flame adjacent to the air layer is partially supplied with oxygen from the air layer, and performs high-load combustion to realize low NOx and complete combustion as the entire flame.

In order to switch the number of burning burners in order to widen the variable range of the combustion amount, when a part of the fuel passage is shut off by a fuel switching valve, the burning burners and the non-burning burners are switched. Air will be ejected from the injection plate at the boundary of the flame, and the state of the flame formed in the combustion chamber will be switched after the repetition of lean flame, rich flame, lean flame, rich flame when viewed from the top of the combustion chamber, A rich flame, an air layer, and a flame at the boundary surface become a stable rich flame to prevent incomplete combustion and realize low NOx and complete combustion in the same manner as described above, in which all burners are burning. .

The function of the second means for solving the problem is that when a part of the fuel passage is shut off, the injection plate forming the second air-fuel mixture chamber facing the boundary of the combustion region has a planar shape and has a vertical direction. By providing a spout, air can be supplied in parallel to the left and right rich flames. Therefore, the flame base of the rich flame is stabilized by the effect of the small vortex formed on the injection plate, and interference between the rich flame and the lean flame can be prevented, and the combustion noise is suppressed.

[0012]

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

FIG. 1 is a partial sectional view of a combustion apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 14 denotes a burner main body including a first air-fuel mixture chamber 15, and a burner main body 1.
A flame outlet 16 having a large number of slits opened on the upper surface of the 4,
A throat portion 17 is formed on the upstream side of the burner main body 14, and a plurality of such burner main bodies 15 are provided together and housed inside a combustion chamber 18 to form a burner block. Also, as shown in FIG. 2, support fittings 19 are attached to both side surfaces of the burner main body 14, and an end portion of the spray plate 20 is inserted into a groove formed by the support fitting 19 and the burner main body 14 so as to be adjacent to each other. The burner main bodies 14 are connected and integrated. The ejection plate 20 is formed by bending a flat plate into a mountain shape, and has a large number of ejection ports 21 in the inclined portion. The space between the adjacent burner bodies 14 and the space surrounded by the injection plate 20 is a second air-fuel mixture chamber 22. A fuel passage 25 having a nozzle 23 for ejecting fuel and a fuel switching valve 24 is provided facing the throat portion 17 of each burner main body 14. A fan 26 is provided in the combustion chamber 18 and supplies air to an air intake 27 formed between the throat 17 and each burner body. When switching the number of burning burners to widen the variable range of the combustion amount, the fuel switching valve 24 is shut off and the fuel is supplied only to the left burner. On both side surfaces of each burner main body 14, a mixture passage 28 communicating the first mixture chamber 15 and the second mixture chamber 22 is provided, but a second boundary which becomes a boundary when the number of burners is switched. The mixture path 28 is not provided on the burner surface facing the mixture chamber 22-a.

In the above configuration, a part of the combustion air supplied from the fan 26 flows into the burner main body 14 from the throat portion 17, and most of the remaining air flows between the burner main body 14 and the burner case 18. And between the burner main body 14 and the respective second mixture chambers 22.
On the other hand, the fuel supplied from the fuel passage 25
3, the fuel is ejected toward each throat portion 17, flows into the burner body 14, and is mixed with the combustion air in the first air-fuel mixture chamber 15. The mixture in the first mixture chamber 15 has a primary air ratio of 20 to 40%. A part of this air-fuel mixture blows out from the flame opening 16 to form a rich flame,
Most of the remaining air-fuel mixture is introduced into the second air-fuel mixture chamber 22 through the air-fuel mixture passage 28 on the side surface of each burner body 14 and mixed with a large amount of air entering from the air intake 27. At this time, after the primary air ratio becomes a lean mixture of about 170 to 250% and is made uniform, the left and right flame outlets 1 are provided from a number of outlets 21 provided on the inclined portion of the outlet plate 20.
It is ejected at an angle in the direction of 6. However, only air is similarly blown out from the mixture chamber 22-a because the mixture path 28 is not provided in the burner body 14 facing the mixture chamber 22-a. Accordingly, the state of the flame formed in the combustion chamber 18 is such that the lean flame (A), the rich flame (B), and the lean flame (A) are repeated from the combustion chamber wall on the left side of the combustion chamber 18, and the mixture chamber 2
At 2-a, a rich flame (B), an air layer (C), and a rich flame (B) are formed, and thereafter, a right flame is repeated by repeating a lean flame (A), a rich flame (B), and a lean flame (A). It becomes a room wall.

Here, the characteristics of lean flame and NOx will be described. The amount of thermal NOx generated decreases as the temperature of the combustion reaction zone decreases. Therefore, it is well known that a lean air-fuel mixture containing a larger amount of air has a higher heat capacity, lowers the flame temperature, and can reduce NOx. However, the flame becomes more unstable as the air-fuel mixture becomes leaner, and the flame base blows off from the flame outlet, causing incomplete combustion.

Therefore, in the above configuration, when all of the burners are burning, a lean mixture is generated by the thermal action of the rich flame formed on the flame opening 16 on the continuous surface of the flame occupying most of the flame. The ambient temperature of the
The lean mixture is completely burned by increasing the flame area and decreasing the flow rate of the lean mixture without increasing the distance between the rich flame and the lean flame by providing a large number of injection ports 21 with inclined portions provided in the At both wall portions of the combustion chamber 18, the lean flame is cut off from the air layer to improve the flammability. Further, in the air-fuel mixture chamber 22-a serving as a boundary, only air is supplied to the rich flame, and the amount of generated NOx is large, but the combustibility is good. Thus, as a whole burner, low N
Ox and complete combustion are realized.

When switching the number of burning burners to widen the variable range of the combustion amount, the fuel switching valve 2
4 is shut off, and fuel is supplied only to the left burner with the second mixture chamber 22-a as a boundary. Since the mixture path is not provided in the burner body 14 facing the second mixture chamber 22-a, air is similarly blown out. Accordingly, the state of the flame formed in the combustion chamber 18 is shown in FIG.
As shown in the figure, the flame becomes a lean flame (A), a rich flame (B), a lean flame (A), a rich flame (B), and an air layer (C) from the combustion chamber wall on the left side of the combustion chamber 18. In other words, the boundary between the burning burner and the non-burning burner is in a state where only air is supplied to the rich flame and the entire burner is burning. Does not burn.

FIGS. 4 and 5 show a second embodiment of the present invention. In each of the drawings, the same components as those in FIGS. 1 and 2 are the same as those in the first embodiment. The difference from the first embodiment is that only the injection plate 20-a forming the second mixture chamber 22-a has a planar shape, and the injection plate 20
The jet port 21-a provided in -a is provided to be open in the vertical direction, and supplies air in parallel to the left and right rich flames. Therefore, the flame base of the rich flame is stabilized by the effect of the small vortex formed on the injection plate 20-a, the interference between the rich flame and the lean flame can be prevented, and the combustion noise can be suppressed.

[0019]

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

According to the first aspect of the present invention, 1) When the number of burning burners is switched to widen the variable range of the combustion amount, the boundary between the burning burners and the non-burning burners is dense. Since only air is supplied to the flame, incomplete combustion does not occur from the discontinuous surface of the flame, low NOx and complete combustion can be realized as in the state where the entire burner is burning, and the combustion amount can be varied. The width (TDR) can be increased.

2) Supplying an excess air-lean mixture from the injection plate depending on the presence or absence of a mixture passage communicating the first mixture chamber and the second mixture chamber contained in the burner body, or The supply of the secondary air can be easily switched, and the overall configuration of the burner is simple and inexpensive.

3) The base of the rich flame which becomes the boundary when switching the number of burning burners to widen the variable range of the combustion amount is stabilized by the effect of the small vortex formed on the injection plate, The combustion noise can be suppressed by preventing interference between the flame and the lean flame, and the operating noise of the combustion device can be reduced.

According to the second aspect, more stable combustion can be expected when the number of burners is switched.

[Brief description of the drawings]

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

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

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

FIG. 4 is a partial sectional view of a combustion apparatus according to a second embodiment of the present invention.

FIG. 5 is a partial cross-sectional view of the same device when a fuel switching valve is operated.

FIG. 6 is a partial sectional view of a conventional combustion device.

[Explanation of symbols]

 Reference Signs List 14 burner main body 15 first air-fuel mixture chamber 16 flame opening 17 air intake part 18 combustion chamber 20 injection plate 21 injection port 22 second air-fuel mixture chamber 24 fuel switching valve 25 fuel passage 28 air-fuel mixture passage

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Ueda 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-6-94219 (JP, A) JP-A-6-94 123409 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 14/02 F23D 14/08 F23C 11/00 329

Claims (2)

(57) [Claims] A burner body containing a fuel-air rich mixture obtained by mixing fuel and combustion air, a burner body including a first air-fuel mixture chamber communicating with the burner port, A plurality of burner bodies are juxtaposed, and a large number of spray ports are provided between the adjacent burner bodies and between the burner body and the combustion chamber walls at both ends of the combustion chamber. A plate, a second mixture chamber formed by being surrounded by the burner body and the injection plate, an air intake provided in the second mixture chamber, and a fuel for supplying fuel to the burner body. A passage, a fuel switching valve that shuts off a part of the fuel passage, and a part of the fuel passage that shuts off an air-fuel mixture passage that communicates the first air-fuel mixture chamber and the second air-fuel mixture chamber. The burner body facing the second mixture chamber facing the boundary of the combustion zone when Pictorial, combustion apparatus provided with the mixture passage in the burner body facing the other second mixture chamber. 2. An injection plate forming a second air-fuel mixture chamber facing a boundary of a combustion region when a part of the fuel passage is shut off, the injection plate having a planar shape and having an injection port in a vertical direction. Combustion equipment.