JP2002267113A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a lean flame by burning air-fuel mixture in three kinds of concentrations through simple constitution and to realize very low NOx through the increase of an excess air factor of a lean flame and the increase of a combustion ratio. SOLUTION: A combustion device comprises a common fuel and air inflow port 53 to produce highly thick air-fuel mixture common to highly thick fuel mixing chambers 62a and 62b and thick fuel mixing chambers 65a and 65b; and communication ports 69 (a communication part) to intercommunicate a thin fuel mixing chamber 57 and the thick fuel mixing chambers 65a and 65b. Thus, in the thick fuel mixing chambers 65a and 65b, the highly thick fuel air-fuel mixture is diluted by thin air-fuel mixture flowing in the thick mixing chambers 65a and 65b through communicating openings 69a and 69b to produce thick air-fuel mixture. Thus, though it is simple in constitution, air-fuel mixture having three kinds of fuel concentrations can be burnt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for home use or business use, and particularly to a combustion apparatus for achieving extremely low NOx.

[0002]

2. Description of the Related Art As global environmental conservation is called for, there is a demand for further reduction of environmentally harmful substances such as NOx (nitrogen oxide) and HC (hydrocarbon) contained in exhaust gas from combustion equipment.

A conventional combustion apparatus of this type is disclosed in Japanese Patent Application Laid-Open No. 2000-2000.
The one described in JP-A-234709 was common. This combustion device is shown in FIG. Thin burner 1
A lean air-fuel mixture chamber 2 containing a lean air-fuel mixture is
On both sides of the lean burner 1, a rich burner 6 containing a rich mixture chamber 4 and connected to a rich flame port 5 is provided in close contact therewith. On the outside of the rich burner 6, a rich burner 9 containing a rich mixture chamber 7 and connected to a rich flame opening 8 is similarly provided in close contact with the lean burner 1 and the rich burners 6 on both sides thereof, and furthermore, The burner module 10 is constituted by integrating the dark burners 9 provided on both sides. A plurality of the burner modules 10 are housed in the burner case 11 and are connected to the combustion chamber 12.

A fuel pipe 13 for supplying fuel and a fan 14 for supplying combustion air are provided upstream of the burner case 11.
Is provided. Here, the fuel pipe 13 and the fan 14
Downstream of the fuel supply system, a lean mixer 15, a rich mixer 16, and a rich mixer 17 are provided in a branched supply system, respectively. The fuel adjusting means 19, the rich fuel adjusting means 20, and the lean air adjusting means 21, the rich air adjusting means 22, and the rich air adjusting means 23 in the air system are connected to the respective mixers. Then, the lean mixer 15 and the lean mixture chamber 2 are in a lean passage 24,
The rich mixer 16 and the rich mixture chamber 4 are connected by a rich passage 25, and the rich mixer 17 and the rich mixture chamber 7 are connected by a rich passage 26. Each passage is provided with branch passages 27a, 27b, 27c for supplying each air-fuel mixture to another burner module 10. The air supply system is provided with an air passage 29 connected to the burner case 11 via an air adjusting means 28 in addition to being connected to each mixer.

In the above configuration, the fuel supplied from the fuel pipe 13 is branched into three, and after being adjusted to a predetermined distribution ratio by the lean fuel adjusting means 18, the rich fuel adjusting means 19 and the rich fuel adjusting means 20, the lean fuel is adjusted. The mixture is supplied to the mixer 15, the rich mixer 16, and the rich mixer 17, respectively. A part of the combustion air supplied from the fan 14 is adjusted to a predetermined flow rate by the air adjusting means 28, and then passes through the air passage 29 to burner case 1
1 and flows out of the combustion chamber 12 through gaps between the burner modules 10. Most of the combustion air is branched into three, and the lean air adjusting means 21 and the rich air adjusting means 2
2. After being adjusted to a predetermined distribution ratio by the rich air adjusting means 23, it is supplied to the lean mixer 15, the rich mixer 16 and the rich mixer 17, respectively. Most of the fuel is supplied to the lean mixer 15 by the lean fuel adjusting means 18, and a large amount of combustion air is supplied to the lean mixer 15 by the lean air adjusting means 21, and becomes a uniform lean mixture through the lean passage 24 and the branch passage 27 a. The mixture is supplied to the lean mixture chamber 2 of the lean burner 1 provided in each burner module 10. The lean air-fuel mixture supplied to the lean air-fuel mixture chamber 2 is ejected from the lean flame port 3 into the combustion chamber 12 to form a lean flame A having a low flame temperature and an extremely low NOx concentration.

Next, a small amount of fuel is supplied to the rich fuel adjusting means 19.
Then, a very small amount of combustion air is flow-regulated by the rich air adjusting means 22 and supplied to the rich mixer 16 to form a uniform rich mixture, which passes through the rich passage 25 and the branch passage 27b to each burner module. The mixture is supplied to the rich mixture chamber 4 provided at 10. The rich mixture supplied to the rich mixture chamber 4 flows out of the rich flame port 5 into the combustion chamber 12 at a low speed and undergoes thermal decomposition to generate a large amount of active chemical species. A "high-temperature / high-reaction zone" B in which the combustion reaction is extremely active is formed at the base of the flame A, and a rich flame C that stabilizes a large amount of the lean flame A at both bases is formed.

Next, a very small amount of fuel is adjusted by the rich fuel adjusting means 20 and a small amount of combustion air is adjusted by the rich air adjusting means 23 and supplied to the rich mixer 17 to form a uniform rich mixture to form a rich rich mixture. The mixture is supplied to the rich mixture chamber 7 provided in each burner module 10 through the branch 26 and the branch passage 27c.
The rich mixture supplied to the rich mixture chamber 7 flows out of the rich flame port 8 into the combustion chamber 12 at a low speed, forms a stable rich flame D, and ignites the rich mixture of the lean burner 6. The rich flame C is generated, and at the same time, the secondary air supplied from between the burner modules 10 completely burns.

As described above, the combustion having these three types of mixture concentrations ignites the rich flame C with the stable rich flame D, and diffuses a large amount of active reactive species, so-called radicals, into the base of the lean flame A. The "high-temperature / high-reaction zone" B is supplied to stabilize the lean flame A firmly. As a result, the combustion ratio of the lean flame A can be increased, and the mixture can be made leaner, as compared with the conventional so-called lean-burn combustion in which a mixture having two concentrations of a rich mixture and a lean mixture is burned. Ultra-low NOx can be realized by suppressing the flame temperature while suppressing HC generated from the flame.

[0009]

However, the above-mentioned conventional combustion apparatus requires three systems of fuel control means, air control means and a mixer in order to form a mixture having three concentrations, and the burner module 10 has Three independent burners are arranged closely. This complicates the configuration,
There was a problem of heavy weight and high cost.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a rich fuel mixing chamber and a common fuel / air inlet common to the rich fuel mixing chamber and for generating a rich fuel mixture. And a communication section for communicating the chamber and the rich mixing chamber.

Therefore, the rich mixture is diluted by the lean mixture that flows through the communicating portion in the rich mixing chamber and flows into the rich mixing chamber, thereby generating a rich mixture. Therefore, it is possible to combust a mixture of three different concentrations while having a simple configuration.

[0012]

The invention according to claim 1 is characterized in that a lean mixing chamber having a lean flame port downstream, a rich mixing chamber adjacent to the lean mixing chamber and having a rich flame port downstream, A rich mixing chamber adjacent to the rich mixing chamber and having a rich flame port downstream, a common fuel / air inlet common to the rich mixing chamber and the rich mixing chamber and for generating a rich mixture, A communication section is provided for communicating the lean mixing chamber with the rich mixing chamber.

Then, the rich mixture is diluted by the lean mixture which flows through the communicating portion in the rich mixing chamber and flows into the rich mixing chamber to generate a rich mixture. Therefore, while having a simple configuration, a mixture of three concentrations is burned to stabilize the lean flame, and an extremely low NOx can be realized by increasing the excess air ratio and the combustion ratio of the lean flame.

According to a second aspect of the present invention, there is provided a lean burner forming body which forms a lean flame port, a lean mixing chamber, and a fuel / air inlet for leaning, and a rich mixing chamber provided outside the lean burner forming body. It comprises a rich burner forming body forming a rich flame port, and a rich mixing chamber and a rich burner forming body forming a rich flame port provided outside the rich burner forming body.

Since the rich mixing chamber and the rich mixing chamber can be formed using the rich burner forming body as a common boundary, the weight can be reduced and the cost can be reduced.

According to a third aspect of the present invention, the lean burner forming body and the rich burner are formed by a convex portion formed by stepping at least one of the lean burner forming body and the rich burner forming body toward the rich mixing chamber. The formed body is brought into close contact with the thin burner-formed body and the densely-burned burner formed body, and a communication port is provided at a close contact portion to form a communication portion.

Further, the lean mixing chamber and the rich mixing chamber can be communicated without providing a separate member, and the configuration can be simplified.

According to a fourth aspect of the present invention, a common mixing chamber independent of the lean mixing chamber, a rich communication port for communicating the common mixing chamber with the rich mixing chamber, and the common mixing chamber and the rich mixing chamber are provided. It is provided with a dense communication port for communication.

The distribution amount to the rich mixture can be easily adjusted by the number and area of the rich communication port and the dense communication port,
It can easily handle various gases.

According to a fifth aspect of the present invention, the lean burner forming body forms a common mixing chamber and a common fuel / air inlet.

Further, a common mixing chamber can be formed without providing a separate member, and the configuration can be simplified.

According to a sixth aspect of the present invention, a secondary air flow is provided outside the rich flame outlet.

The rich flame can be completely burned by the secondary air, and the lean flame is stabilized by the "high temperature and high reaction zone" formed by the rich mixture supplied from the rich flame port. I have. Therefore, even when the amount of air increases due to a strong wind or the like and the lean mixture becomes thin, instability of the lean flame is suppressed beforehand, and as a result, generation of a large amount of unburned products such as HC can be suppressed beforehand. In addition, it is cooled by the secondary air, so that overheating of the flame outlet at the time of small input can be suppressed.

According to a seventh aspect of the present invention, the amount of fuel supplied to the lean mixing chamber is made larger than the sum of the amounts of fuel supplied to the rich mixing chamber and the rich mixture chamber.

Further, the combustion ratio of a lean flame having a low NOx concentration can be increased to realize ultra-low NOx.

[0026]

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

(Embodiment 1) FIG. 1 is a side view showing a combustion apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

1 and 2, reference numeral 50 denotes a burner module. A plurality of burner modules 50 are arranged in parallel. Reference numeral 51 denotes a lean fuel / air flow inlet, and a lean fuel nozzle 52 faces the lean fuel nozzle 52. Reference numeral 53 denotes a common fuel / air inlet, and a common fuel nozzle 54 is opposed to the common fuel / air inlet 53.

Reference numerals 55a and 55b denote lean burner forming bodies, which form a lean mixing chamber 57 having a lean flame port 56 downstream. Further, a common mixing chamber 58 independent of the lean mixing chamber 57 is formed. Lean flame outlet 5 subdivided by slit 59
6 are formed. The upstream end opening of the lean mixing chamber 57 becomes the fuel / air inlet 51 for leaning, and the upstream end opening of the common mixing chamber 58 becomes the common fuel / air inlet 53.

Numerals 60a and 60b denote rich burner forming bodies, and the lean burner forming body 55a and the rich burner forming body 6
0a is a rich mixing chamber 62a having a rich flame port 61a downstream
Similarly, the lean burner forming body 55b and the rich burner forming body 60b form a rich mixing chamber 62b having a rich flame port 61b downstream. 63a and 63b are rich burner forming bodies, and the rich burner forming body 60a and the rich burner forming body 63a form a rich mixing chamber 65a having a deep flame port 64a downstream. The rich burner forming body 63b forms a deep mixing chamber 65b having a deep flame port 64b downstream.

Reference numerals 66a and 66b denote rich mixing chambers 62, respectively.
a and the common mixing chamber 58, and the rich mixing chamber 62b and the common mixing chamber 5
This is an over-concentration communication port for communicating 8. 67a, 67b
Are thick communication ports for communicating the rich mixing chamber 65a with the common mixing chamber 58 and the rich mixing chamber 65b with the common mixing chamber 58, respectively.

Reference numerals 68a and 68b denote convex portions (communication portions) which step up a part of the rich burner forming bodies 60a and 60b toward the rich mixing chambers 62a and 62b, respectively.
Are in close contact with the thin burner forming bodies 55a and 55b, respectively. 69a and 69b are the lean mixing chambers 5 respectively.
7, rich mixing chamber 65a, lean mixing chamber 57 and rich mixing chamber 65b
Is a communication port (communication part) for communicating with. A plurality of burner modules 50 are arranged at predetermined intervals, and a secondary air flow 70 is formed between the burner modules 50.

Next, the operation and the operation will be described. The fuel gas injected from the lean fuel gas outlet 52 and the air supplied by the fan (not shown) flow from the lean fuel / air inlet 51. The fuel and air are mixed in the lean mixing chamber 57 to become a lean mixture having an excess air ratio of more than one.

The fuel gas ejected from the common fuel nozzle 54 and the air supplied by the fan (not shown) flow through the common fuel / air inlet 53, respectively. In the common mixing chamber 58, an enriched mixture having an excess air ratio of less than 1 is formed. A part of the rich mixture is supplied to the rich communication port 66, respectively.
a, 66b and flows into the rich mixing chambers 62a, 62b. The remaining rich mixture is supplied to the rich communication ports 67a and 67, respectively.
7b flows into the rich mixing chambers 65a and 65b. On the other hand, a part of the lean mixture is connected to the communication ports 69a and 69b, respectively.
And flows into the rich mixing chambers 65a and 65b. The rich mixture in the rich mixing chambers 65a and 65b is diluted with the lean mixture to form a rich mixture having an air excess ratio slightly smaller than 1. Of the air supplied by the fan, air that does not flow into the burner module 50 from the dilution fuel / air inlet 51 and the common fuel / air inlet 53 becomes the secondary air flow 70.

The lean air-fuel mixture flows out of the lean flame port 56 to form a lean flame A having a low flame temperature and an extremely low NOx concentration. The rich mixture flows out of the rich flame ports 61a and 61b, undergoes thermal decomposition to generate a large amount of active chemical species, and the diffusion supply causes a very active combustion reaction at the base of the lean flame A. A high reaction zone "B" is formed and a large amount of lean flame A
Is formed at the bases on both sides. Further, the rich mixture flows out of the rich flame ports 64a and 64b to form a stable rich flame D, and ignites the rich mixture to generate a rich flame C. The rich flame D is completely burned by the secondary air flow 70.

As described above, the "multi-concentration combustion" having these three types of mixture concentration ignites the rich flame C with the stable rich flame D, which is provided even in the conventional rich-and-dark combustion, and provides a large amount of activity. By diffusing and supplying the reactive chemical species, so-called radicals, to the base of the lean flame A, a “high temperature / high reaction zone” B is formed, and the stabilization of the lean flame A is greatly promoted. As a result, the combustion ratio of the lean flame A can be increased, and the mixture can be made leaner, as compared with the conventional so-called lean-burn combustion in which a mixture having two concentrations of a rich mixture and a lean mixture is burned. Ultra-low NOx can be realized by suppressing the flame temperature while suppressing HC generated from the flame A.

As described above, the rich mixing chambers 62a and 62b
And a common fuel / air inlet 53 common to the rich mixing chambers 65a and 65b and for generating a rich mixture;
Communication portions (projections 68a, 68b and communication ports 69a, 69) for communicating the lean mixing chamber with the rich mixing chambers 65a, 65b.
b). And the rich mixing chamber 65a, 65b
The rich mixture is diluted by the lean mixture flowing into the rich mixing chambers 65a and 65b through the communicating portion in the above to generate a rich mixture. Therefore, it is possible to combust a mixture of three different concentrations while having a simple configuration.

Further, the combustion device is constituted by the rich burner forming bodies 60a, 60b provided outside the lean burner forming bodies 55a, 55b and the rich burner forming bodies 63a, 63b provided outside the rich burner forming bodies 60a, 60b. Is composed. Then, the rich mixing chambers 62a and 62b and the rich mixing chambers 65a and 65b are set with the rich burner forming bodies 60a and 60b as a common boundary.
Since b can be formed, weight reduction and low cost can be realized.

Further, the thin burner forming bodies 55a, 55b
And at least one of the rich burner forming bodies 60a, 60b is stepped toward the rich mixing chambers 62a, 62b to form the lean burner forming bodies 55a, 55 by convex portions 68a, 68b formed.
b and the dense burner forming bodies 60a and 60b are brought into close contact with each other, and communication ports 69a and 69b are provided in the contact portions to form a communication section. Then, the lean mixing chamber 57 and the rich mixing chambers 65a and 65b can be communicated without providing a separate member, and the configuration can be simplified.

Further, a common mixing chamber 58 independent of the lean mixing chamber 57, a common mixing chamber 58 and a rich mixing chamber 62a,
There are provided rich communication ports 66a and 66b for communicating the 62b and dense communication ports 67a and 67b for communicating the common mixing chamber 58 and the rich mixing chambers 65a and 65b. Then, the distribution amount of the rich mixture can be easily adjusted by the number and area of the rich communication ports 66a, 66b and the rich communication ports 67a, 67b, so that various gases can be easily handled.

The lean burner forming bodies 55a and 55b form a common mixing chamber 58 and a common fuel / air inlet 53. Then, the common mixing chamber 58 is provided without providing a separate member.
Can be formed, and the configuration can be simplified.

Further, a secondary air flow 70 is provided outside the rich flame ports 64a and 64b. The rich flame D can be completely burned by the secondary air, and the rich flame ports 61a and 61a
The lean flame A is stabilized by the "high temperature / high reaction zone" B formed by the rich mixture supplied from 1b. Therefore, even when the amount of air increases due to a strong wind or the like and the lean mixture becomes thin, the instability of the lean flame A is suppressed beforehand, and as a result, the generation of a large amount of unburned products such as HC can be suppressed beforehand. . In addition, it is cooled by the secondary air, so that overheating of the flame outlet at the time of small input can be suppressed.

Further, the amount of fuel supplied to the lean mixing chamber 57 is increased by the rich mixing chambers 62a and 62b and the rich mixing chambers 65a and 65b.
5b is larger than the sum of the fuel supply amounts to 5b.
Then, the combustion ratio of the lean flame A having a low NOx concentration is increased, and the ultra-low NOx can be realized.

In each embodiment, the fuel has been described as a gaseous fuel such as city gas. However, a liquid fuel such as kerosene may be vaporized and used.

[0045]

As described above, according to the first to seventh aspects of the present invention, a mixture having three concentrations is burned to achieve a lean structure while realizing a simple structure, a reduction in weight and a low cost. The flame is stabilized, and an extremely low NOx can be realized by increasing the excess air ratio and the combustion ratio of the lean flame.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a main part of the embodiment.

FIG. 3 is a front view of a conventional combustion device.

[Explanation of symbols]

 51 Lean fuel / air inlet 53 Common fuel / air inlet 55a, 55b Lean burner forming body 56 Lean flame 57 Lean mixing chamber 58 Common mixing chamber 60a, 60b Rich burner forming 61a, 61b Rich flame 62a , 62b Rich mixing chamber 63a, 63b Rich burner forming body 64a, 64b Rich flame port 65a, 65b Rich mixing chamber 66a, 66b Rich communication port 67a, 67b Rich communication port 68a, 68b Convex part (communication part) 69a, 69b Communication port (communication part) 70 Secondary air flow

Continued on the front page (72) Inventor Ma Tate group 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 3K017 AA06 AB02 AB07 AB08 AC02 AD01 AD04 AD11 3K065 TA01 TA15 TD05 TH01 TH04

Claims (7)

[Claims] A lean mixing chamber having a lean flame port downstream;
A rich mixing chamber adjacent to the lean mixing chamber and having a rich flame port downstream; a rich mixing chamber adjacent to the rich mixing chamber and having a rich flame port downstream; the rich mixing chamber and the rich mixing chamber; A combustion device, comprising: a common fuel / air inlet that is common to the chambers and generates an rich mixture; and a communication unit that communicates the lean mixing chamber and the rich mixing chamber. 2. A lean burner forming body for forming a lean burn port, a lean mixing chamber, and a fuel / air inlet for leaning, and a rich mixing chamber and a rich burn port provided outside the lean burner forming body. 2. The combustion apparatus according to claim 1, further comprising a rich burner forming body, and a rich burner forming body provided outside the rich burner forming body and forming a rich mixing chamber and a rich flame outlet. 3. The lean burner forming body and the rich burner forming body are brought into close contact with each other by a convex portion formed by stepping at least one of the lean burner forming body and the rich burner forming body toward the rich mixing chamber. The combustion device according to claim 2, wherein a communication port is provided by providing a communication port at a contact portion between the lean burner forming body and the over-rich burner forming body. 4. A common mixing chamber independent of the lean mixing chamber, a rich communication port for communicating the common mixing chamber with the rich mixing chamber,
The combustion device according to any one of claims 1 to 3, further comprising a dense communication port for communicating the common mixing chamber and the rich mixing chamber. 5. The combustion device according to claim 4, wherein the lean burner forming body forms a common mixing chamber and a common fuel / air inlet. 6. The combustion apparatus according to claim 1, wherein a secondary air flow is provided outside the rich flame outlet. 7. The combustion apparatus according to claim 1, wherein the amount of fuel supplied to the lean mixing chamber is larger than the sum of the amount of fuel supplied to the rich mixing chamber and the rich mixture chamber.