JP2914885B2 - Concentration combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an enrichment burner for burning a rich air-fuel mixture formed at one end thereof. And a plurality of flat rich combustion sections formed with a rich introduction port for introducing combustion air, and a plurality of flat rich combustion sections are arranged side by side with an interval therebetween, and the lean flame port for burning a light mixture is the rich flame port. End face on the same side as
A flat mixing chamber formed between adjacent thickening flame ports and formed with a light mixing chamber communicating with the light mixing port and a light introduction port for introducing a fuel gas or an air-fuel mixture into the light mixing chamber. The present invention relates to a rich-burning apparatus in which a light-burning section is formed between adjacent rich-burning sections with the above-described rich-burning section as a constituent member, and a straightening plate along a flow direction of a light-air mixture is provided at each of the light-flame ports.

[0002]

2. Description of the Related Art A rich / lean combustion apparatus having such a structure burns a rich air / fuel mixture capable of performing stable combustion with a small air mixing ratio at a rich flame, and a flame holding action by the combustion flame of the rich air / fuel mixture. Thus, the lean air-fuel mixture having a large air mixing ratio in the lean flame is stably and continuously burned, and the combustion device as a whole is stably burned while minimizing the generation of NOx. In such a lean-burn apparatus, NO
In order to minimize the generation of x, it is necessary to mix the fuel gas and the combustion air well, especially in a lean mixture.

For this reason, in the prior art, a part of a flow straightening plate provided in a light flame outlet is swollen to generate a turbulent flow in a light air-fuel mixture to promote mixing. 6
As disclosed in Japanese Patent Publication No. 193832, a plurality of straightening plates are provided in the light flame outlet, and a communication hole is formed in each straightening plate, and a part of the lean gas mixture is passed through the communication hole. Some have been configured to be fed into an adjacent lean mixture stream, thereby promoting the mixing of the fuel gas with the combustion air.

[0004]

However, in a configuration in which a part of the current plate is swelled, it is possible to agitate the fuel gas and the combustion air by the turbulent flow. However, since the mixture is only stirred with a lump having a certain size, the mixing of the two is not sufficient, and there is room for improvement in this respect. That is, since the fuel gas and the combustion air flow as a certain amount of lump each, simply stirring by turbulence causes the mixture to remain almost as a lump, and the concentration of the fuel gas locally increases. There are high-concentration and high-air-concentration parts, and high-concentration fuel-gas-concentration parts generate a large amount of NOx. Was.

[0005] Further, in the structure disclosed in the above publication, when the fuel gas or the combustion air passes through the communication hole, it is fragmented at the end of the communication hole. More thorough mixing can be expected as compared to those. However, only a part of the fuel gas or the combustion air passes through the communication hole, and in this sense, the segmentation is insufficient, and further, the flow resistance of the lean mixture is reduced by the communication hole. Because of a considerable increase, it is necessary to increase the capacity of the fan by increasing the number of revolutions of the fan for supplying the combustion air, and there is a problem that the noise increases accordingly.

The present invention focuses on such various problems of the prior art, and an object of the present invention is to mix a fuel gas and combustion air in a lean mixture without significantly increasing flow resistance. It is an object of the present invention to provide a concentration combustion apparatus which can achieve good mixing to achieve low NOx and low CO, and which is structurally simple and can be implemented at low cost.

[0007]

In order to achieve this object, a first characteristic configuration of the concentration combustion apparatus according to the present invention is that an enrichment flame for burning a rich mixture is formed on one end face, A plurality of flat rich combustion sections formed with a rich mixing chamber communicating with the flame port and a rich inlet port for introducing fuel gas and combustion air into the rich mixing chamber are arranged in parallel at intervals. A light mixing port for burning the light mixture is formed on the same end face as the above-described rich mixing port and between adjacent thick mixing ports, and the light mixing port communicating with the light mixing port is provided. A flat lean combustion section in which a chamber and a lean inlet for introducing a fuel gas or an air-fuel mixture into the lean mixing chamber are formed between adjacent rich combustion sections using the rich combustion section as a constituent member. A boiler / burner in which a baffle plate is provided in each of the flare ports along a flow direction of a lean mixture, wherein the baffle plate is provided. Lies in providing a plurality of cutout portions over substantially the entire length of the upstream side end portion of the light gas mixture flow direction.

[0008] A second characteristic structure is that a notch is provided at the upper end of the flow straightening plate in the flow direction of the lean mixture.
Further, the present invention is characterized in that a plurality of notches are provided over substantially the entire length of the lower end in the flow direction of the lean mixture.

A third characteristic configuration is that a plurality of rectifying plates are provided in each of the lightening flame openings, and the cutout portions are provided at ends of the rectifying plates.

A fourth characteristic configuration is that the notch is a rectangular notch.

A fifth characteristic configuration is that a notch provided at an upper end or a lower end of the current plate in the flow direction of the lean mixture, or a cutout provided at both ends of the upper and lower sides is adjacent to each other. The point is that the positions are different between the current plate in the direction along the end.

[0012]

According to a first characteristic configuration of the present invention, there is provided a concentration combustion apparatus having the above-mentioned configuration, wherein a plurality of flow straightening plates provided at each of the leaning ports have a plurality of air flow ends on the upstream side in the light mixture flow direction. Since the notches are provided, the fuel gas and the combustion air, which are formed into a certain amount of lump, are subdivided by the ends of the notches, and the notches are formed of the current plate. Since it is provided over almost the entire length of the superior side end, it is finely divided and mixed over almost the entire length of the lightening flame in the longitudinal direction, and a portion having a locally high fuel gas concentration is generated. An increase in the generation of NOx and an increase in the generation of CO due to a portion having a high air concentration are suppressed as much as possible. Moreover, since the notch is only provided at the upper end of the flow straightening plate in the flow direction of the lean air-fuel mixture, the flow resistance of the lean air-fuel mixture does not extremely increase, and the structure is extremely simple and low. It can be implemented at cost.

According to the second characteristic configuration, the notch is provided at the upper end of the straightening vane in the flow direction of the lean air-fuel mixture. Since a plurality of cutouts are provided, the opportunities for subdivision of the fuel gas and combustion air increase, and the subdivision is further promoted by that amount, and the fuel gas and combustion air are more effectively mixed. As a result, generation of NOx and CO is suppressed.

According to the third characteristic configuration, a plurality of rectifying plates are provided in each of the lightening flame openings, and the cutout portions are provided at ends of the rectifying plates. The fuel gas and the combustion air are equally and finely divided and mixed not only in the length direction of the fuel port but also in the lateral direction of each light port, further suppressing the generation of NOx and CO. Is done.

According to the fourth characteristic configuration, since the notch is a rectangular notch, turbulent flow due to the notch is more remarkable than, for example, a notch having a smooth curve. Accordingly, the opportunity for subdivision of the fuel gas and the combustion air is increased and the subdivision is promoted, and the NOx and CO
Is suppressed.

According to the fifth characteristic configuration, the notch provided at the upper end or the lower end of the straightening vane in the flow direction of the lean mixture, or at the both ends of the upper side and the lower side,
Because the position is different in the direction along the end between adjacent straightening plates, the fuel gas and the combustion air are equally and finely divided uniformly over the length direction and the width direction of each light flame port. The mixture can be mixed, and the lean mixture can be satisfactorily burned at each of the lean flame outlets while suppressing the generation of NOx and CO.

[0017]

As described above, according to the first characteristic configuration, the fuel gas and the combustion air are subdivided by the plurality of cutouts provided at the upper end of the current plate in the flow direction of the lean mixture. It is possible to suppress as much as possible that a portion with a high fuel gas concentration is locally generated and NOx is generated, and a portion with a high air concentration is generated and CO is increased as much as possible. In addition, the flow resistance of the lean air-fuel mixture does not extremely increase, the structure is extremely simple, and it can be implemented at low cost.

According to the second characteristic configuration, the notches are provided at the upper end and the lower end of the straightening vane in the flow direction of the lean mixture, so that the fuel gas and the combustion air can be subdivided. Thus, generation of NOx and CO can be further suppressed.

According to the third characteristic configuration, a plurality of straightening plates are arranged at each light emitting port and a cutout portion is provided at an end of each straightening plate, so that the length of each light emitting port is reduced. Not only in the direction but also in the lateral width direction of each lightening flame port, the fuel gas and the combustion air can be equally finely divided and mixed, and the generation of NOx and CO can be suppressed.

According to the fourth characteristic configuration, by making the notch rectangular, the generation of turbulence due to this notch is increased, thereby promoting the fragmentation of the fuel gas and the combustion air. The generation of NOx and CO can be suppressed.

According to the fifth characteristic configuration, the cutout portion is located at different positions in the direction along the end portion of the current plate between adjacent current plates, so that the length direction and the lateral width of each light flame outlet are changed. The fuel gas and the combustion air can be uniformly subdivided and uniformly mixed in the direction, and the lean mixture can be favorably burned while suppressing the generation of NOx and CO in each lean flame. Can be.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concentration combustion apparatus according to the present invention is used for, for example, a burner unit of a hot water supply apparatus. As shown in FIGS. 1 to 3, a burner case 1 has a box-shaped frame 2 inside. A large number of burners 3 for rich combustion as flat rich burners are housed side by side at predetermined intervals. A fan 4 for supplying combustion air is located below the burner case 1, and a discharge port 4 a of the fan 4 is opened at the bottom of the burner case 1.
An air chamber 5 is formed between the bottom of the box-shaped frame 2 and the bottom of the box-shaped frame 2.

The rich combustion burner 3 has a flat rich flame opening 6 for discharging a rich air-fuel mixture having a low primary air mixing ratio upward.
An enrichment mixing chamber 7 communicating with the enrichment flame 6, an enrichment inlet 8 for introducing a fuel gas for generating an enriched mixture and combustion air into the enrichment mixing chamber 7, and the like. ing. The rich combustion burner 3 is formed from a single metal plate, and the plate is bent at the portion of the rich flame 6 and stuck together. The gas inlet 8 is formed, and a gas passage 10 for light combustion of a burner 9 for light combustion, which will be described later, is provided below the mixing chamber 7 for rich combustion. Is formed integrally with the same plate-shaped body, the periphery thereof is joined by spot welding, and a plurality of concentrated flames having three slit holes in the bent portion. A mouth 6 is formed.

The flat rich burners 3 formed in this manner are arranged side by side in the box-shaped frame 2 at a predetermined interval, so that the flat rich burners 3 are flat between adjacent burners. An interval space is created, and this interval space is used for forming the burner 9 for light combustion as a light combustion portion. Specifically, between the rich flame ports 6 of the burner 3 for rich combustion, a lean flame port 12 for discharging a light air-fuel mixture having a high primary air mixing ratio upward is formed. Is formed as a light mixing chamber 13, and the air-fuel mixture is blown into the light mixing chamber 13 from a plurality of outlets 14 formed in the light gas passage 10. Is configured.

As is apparent from FIG. 3, a metal flame for rectifying and discharging the lean air-fuel mixture is provided in each lean flame port 12 of the light-burning burner 9 along the flow direction of the lean air-fuel mixture. Rectifying plates 15 are provided four by four. These four rectifying plates 15 are grouped in pairs, and the two rectifying plates 15 provided on the left side are connected to the burner 3 for rich combustion on the left side, and the two rectifying plates 15 provided on the right side. Is the burner 3 for rich combustion on the right side, and FIG.
As shown in FIG. End portions 15 of these straightening plates 15 on the upstream side in the flow direction of the lean mixture.
a, a plurality of notches 16 are provided at the end portions 15 of the current plate 15.
It is formed continuously over almost the entire length of a. FIG.
Is a rectangular notch 16a, and between the adjacent straightening plates 15, these rectangular notches 16a
They are arranged at different positions in the direction along the end 15a of the current plate 15.

The rich inlet 8 of the rich burner 3 and the light inlet 11 of the light burner 9 are open in the same direction and are close to each other. A concentrated gas header 17 for distributing and supplying the fuel gas and a lean gas header 18 for distributing and supplying the lean fuel gas are located.
These two headers 17 and 18 are arranged vertically with the rich gas header 17 facing upward, and the rich gas header 1 above the rich gas header 1.
A number of rich gas nozzles 19 are attached to 7, and a light gas nozzle 20 is attached to the lower gas header 18 below. The rich gas header 17 has a rich gas supply passage 21, and the lean gas header 18 has a lean gas supply passage 22.
Are connected to each other, and these two supply paths 2
Main gas supply path 23 upstream from the branch point of 1, 22
Is provided with a main gas amount adjusting valve V for adjusting the total amount of fuel gas to be supplied.

Each of the enrichment gas nozzles 19 faces each of the enrichment inlets 8 and blows fuel gas from the enrichment gas nozzles 19 so that combustion air in the air chamber 5 is discharged at a predetermined rate by an ejector action. Suction into the concentration inlet 8,
The mixture is mixed in the passage of the mixture chamber 7 to form a rich mixture,
This rich mixture is discharged from the thick flame 6. Similarly, each light gas nozzle 20 faces each light inlet 11,
By blowing the fuel gas from the lean gas nozzle 20,
The combustion air in the air chamber 5 is sucked into the lean gas inlet 11 at a predetermined ratio by an ejector action, and is mixed in advance in the passage of the lean gas conduit 10, and the mixture is injected into the lean gas conduit 10. It is jetted from the outlet 14 into the mixing chamber 13 for light. And
In the light mixing chamber 13, the air-fuel mixture from the jet port 14 and the combustion air from the air chamber 5 are mixed to generate a light air-fuel mixture, and the light air-fuel mixture is discharged from the light-flame port 12.

The light mixture thus generated is discharged from the light flame port 12 and burned. At the same time, the rich air port 6 adjacent to the light flame port 12 has a small primary air mixing ratio and has By discharging and burning a rich air-fuel mixture capable of stable combustion, the lean air-fuel mixture can be stably and continuously burned by the flame holding action of the combustion flame of the rich air-fuel mixture. Stable combustion is possible while minimizing the generation of NOx. In addition, a rectangular notch 16a is formed continuously on the upper end 15a of each straightening plate 15 in the direction of the flow of the lean mixture over substantially the entire length thereof. Generation can also be suppressed.

That is, since the rectangular notch 16a is formed at the upper end 15a of each straightening plate 15 in the direction of the flow of the lean mixture, the fuel gas and the combustion air, which are formed into a certain mass, The end of the notch 16a is subdivided, and a portion having a high fuel gas concentration is locally generated to increase the generation of NOx, or a portion having a high air concentration is generated to increase the generation of CO. Is suppressed.
FIG. 5 is a graph that facilitates understanding of this. For example, assuming that the set air-fuel ratio of the lean air-fuel mixture is φ, the conventional air-flow end of the straightening air-flow direction of each straightening plate 15 is flat. , The air-fuel ratio distribution as shown by the broken line, and in the case of the structure of this embodiment, the air-fuel ratio distribution as shown by the solid line.

Various experiments were conducted on the present invention prior to implementation, and FIG. 6 shows a part of the experimental results. In the graph of FIG. 6, the vertical axis represents the values of NOx and CO, and the horizontal axis represents the excess air ratio.
The conventional one having no notch in both the 5a and the lower end 15b is indicated by a broken line, and the rectangular notch 16a formed in the upper end 15a and the lower end 15b is indicated by a solid line. A portion formed with a rectangular notch 16a only in the portion 15a is indicated by a dashed line. As is clear from the results of this experiment,
By providing the rectangular notch 16a and appropriately setting the excess air ratio, it can be confirmed that the generation of NOx and CO can be suppressed at once. To disclose an example of the specific numerical value, when Ip is 30,000 Kcal / h and the excess air ratio is set to 1.6, the conventional one shown by the broken line is set to 100%, and the upper end 15a is Lower end 15
b, a rectangular notch 16a is formed in the
To about 96.8% and CO to about 66.7%,
In the case where the rectangular notch 16a is formed only in the upper end 15a, NOx is about 91.4% and CO is about 83.3%.
%.

[Other Embodiments] In the above embodiment, the rectangular cutouts 16a are formed only at the upper end 15a of each straightening plate 15 in the light mixture flow direction. As shown by the solid line in the experimental results, a rectangular cutout 16a can be formed at both the upper end 15a and the lower end 15b in the light mixture flow direction. Further, the notch 16 does not necessarily have to be a rectangular notch 16a, and can be variously changed, and FIG. 7 shows an example.

That is, as shown in (a), a semicircular notch 16c is formed at both ends 15a and 15b, and
It is possible to dispose them at different positions in the direction along the current plate 15, and in this case, it is also possible to arrange them at the same position in the direction along the current plate 15, or
c may be formed only on the upper end 15a.

(B) As shown in FIG.
d are formed at both ends 15a and 15b, and the upper end 15a has the same position in the direction along the rectifying plate 15, and the lower end 15b has a position in the direction along the rectifier plate 15. Can be arranged differently, and in this case, it can be formed only on the upper end 15a.

Further, a rectangular notch 16a or a saw-like notch is formed in the lower end 1a.
The semicircular notch 16c or the triangular notch 16d may be formed in 5b, or vice versa. In short, various conditions are set for the shape and arrangement of the notch 16. It can be changed freely under consideration.

Incidentally, reference numerals are written in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is a right side sectional view of a combustion device.

FIG. 2 is a partially cutaway perspective view of a combustion device.

FIG. 3 is an enlarged cross-sectional front view of the combustion device.

FIG. 4 is a perspective view of a rich combustion portion and a flow straightening plate.

FIG. 5 is a graph showing a relationship between an air-fuel ratio and a frequency distribution.

FIG. 6 is a graph showing the relationship between excess air ratio and NOx and CO concentrations.

FIG. 7 is a perspective view of a flow straightening plate and a rich combustion section showing another embodiment.

[Explanation of symbols]

 3 Rich Burning Section 6 Rich Flame Port 7 Rich Mixing Room 8 Rich Burning Port 9 Light Burning Section 11 Light Burning Port 12 Light Flame Port 13 Light Mixing Room 15 Rectifier Plate 15a Upper End of Rectifier Plate 15b Lower end of current plate 16 Notch 16a Rectangular notch

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23D 14/08 F23C 11/00 329

Claims (5)

(57) [Claims] 1. An enrichment opening (6) for burning a rich mixture is formed at one end surface, and an enrichment mixing chamber (7) communicating with the enrichment opening (6); A plurality of flat rich combustion sections (3) formed with (7) an enrichment inlet (8) for introducing fuel gas and combustion air are arranged side by side with an interval therebetween, and a lean air-fuel mixture is formed. A burning light port (12) that burns is formed on the same end surface as the thick burning port (6) and between adjacent thick burning ports (6). A flat lean combustion section (9) having a light mixing chamber (13) communicating therewith and a light inlet (11) for introducing a fuel gas or an air-fuel mixture into the light mixing chamber (13), The rich combustion section (3)
Is formed between adjacent rich combustion sections (3) as a constituent member, and a straightening plate (15) is disposed in each of the lean burn ports (12) along the flow direction of the lean air-fuel mixture. The notch (1) extends over substantially the entire length of the upstream end (15a) of the straightening plate (15) in the flow direction of the lean mixture.
6) A concentration combustion device provided with 6). 2. The lean-burn combustion apparatus according to claim 1, wherein a plurality of cutouts (16) are provided over substantially the entire length of the lower end (15b) of the straightening vane (15) in the flow direction of the lean mixture. 3. A plurality of rectifying plates (15) are provided in each of the lightening flame openings (12), and the cutout portions (16) are provided at ends of the rectifying plates (15). The lean-burn combustion apparatus according to claim 1 or 2 . 4. A cut-out portion of the notch (16) is rectangular (1
The lean burn device according to claim 3, which is 6a). Pale mixture ends of the upstream side or downstream side of the flow direction of wherein said current plate (15), or notch provided on the end portions on both sides of the upstream side and the downstream side (16), adjacent 5. The light-to-dark combustion apparatus according to claim 3 , wherein positions of the flow straightening plates (15) are different from each other in a direction along an end.