JP2002213714A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform reliable ignition while realizing very low NOx and to suppress discharge of an unburnt material, such as HC during ignition. SOLUTION: A combustion device comprises a lean burner port 51 through which lean mixture flows out; an excess dense burner port 53a formed in vicinity of the lean burner port 51 and through which fuel or excess dense mixture flows out; a dense burner port 53a situated in the vicinity of the excess dense burner port 52a and through which dense admixture flows out; and a first electrode 54 and a second electrode 55 forming high pressure discharge α crossing the downstream parts of the excess dense burner port 52a and the dense burner port 53a. This constitution generates mixture concentration, most apt to ignite, in some position of a generation part of high voltage discharge α regardless of a fluctuation of an excess air factor due to a fluctuation in a fuel feed amount or the number of revolutions of a fan even when a ratio of a fuel feed amount to the lean burner port 51 to reduce NOx to a very low value is increased, and performs reliable ignition.

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 No. 2839.
No. 049 was generally used. This combustion device is shown in FIG.

[0004] The lean burner unit 1a and the rich burner unit 1b have a lean flame port 2a and a rich flame port 2b at the upper part, respectively, and a lean inlet 3a and a rich inlet port 3b at the lower side. The lean burner units 1a and the dense burner units 1b are arranged alternately. An electrode 4 to which a high voltage is applied is disposed downstream of the dense flame outlet 2b. 5a is a lean flame formed on the lean flame port 2a, 5b is a rich flame port 2b
It is a deep flame formed above.

In the above configuration, fuel and air flow from the lean inlet 3a, are mixed in the lean burner unit 1a, and a lean air-fuel mixture is generated.
A lean mixture flows out from a. On the other hand, fuel and air flow in from the rich inlet 3b, are mixed in the rich burner unit 1b, and a rich air-fuel mixture is generated, and the rich air-fuel mixture flows out from the rich flame port 2b. At the time of ignition, a high voltage is applied to the electrode 4, a high-pressure discharge is formed between the electrode 4 and the rich flame port 2b, and the rich mixture is ignited to form a lean flame 5a and a rich flame 5b. The lean flame 5a having a low flame temperature and a low NOx generation amount and having poor combustibility is stabilized by the stable rich flame 5b having a high flame temperature and a large NOx generation amount, so that the NOx generation amount can be suppressed as a whole.

[0006]

In order to further reduce NOx, it is necessary to further increase the ratio of the fuel supply amount to the lean burner unit 1a. However, if the ratio of the amount of fuel supplied to the lean burner unit 1a is further increased in the conventional combustion apparatus, the amount of supply to the rich burner is reduced. However, the problem is that the rich air-fuel mixture becomes lean and difficult to ignite under the influence of a lean air-fuel mixture with poor flammability, and a large amount of unburned substances such as HC are discharged at the time of ignition. was there.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a rich flame port and an electrode for forming a high-pressure discharge across the downstream portion of the rich flame port.

Accordingly, the rich mixture and the rich mixture flow through the portion where the high-pressure discharge is formed, and diffuse each other. Then, regardless of the magnitude of the excess air ratio, the concentration of the air-fuel mixture that is most likely to ignite is formed, and ignition can be reliably performed even if the supply amount ratio to the lean flame is increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is characterized in that a lean flame outlet from which a lean air-fuel mixture flows out, and a rich flame outlet provided in close proximity to the lean air-hole and from which fuel or a rich air-fuel mixture flows out. When,
A rich flame outlet is provided in proximity to the rich flame outlet, through which the rich mixture flows out, and an electrode for forming a high-pressure discharge across the rich flame port and a downstream portion of the rich flame port. .

[0010] Irrespective of fluctuations in the excess air ratio due to fluctuations in the amount of fuel supplied or the number of revolutions of the fan, the most ignitable mixture concentration occurs at any position in the high-pressure discharge formation section. Therefore, ignition can be reliably performed, and emission of unburned substances such as HC at the time of ignition can be suppressed.

According to a second aspect of the present invention, in particular, in the first aspect, the tips of the electrodes are disposed at the downstream of the rich flame port and the downstream of the rich flame port, respectively.

Further, a high-pressure discharge that crosses the rich flame port and the downstream portion of the rich flame port can be reliably formed, and the ignition can be more reliably performed.

According to a third aspect of the present invention, in particular, in the first aspect, the tip of the electrode is provided at a downstream portion of the rich flame port, and a protruding portion is provided near a tip of the electrode at a boundary between the rich flame port and the lean flame port. And a high voltage is applied to the electrode and the protrusion to form a high-voltage discharge.

[0014] Even with a single electrode, a high-pressure discharge that crosses the rich flame port and the downstream portion of the rich flame port can be reliably formed, and the ignition can be reliably performed.

According to a fourth aspect of the present invention, in particular, in the first aspect, the tip of the electrode is provided downstream of the rich flame port, and the tip of the electrode at the boundary of the rich flame port far from the rich flame port. A protruding portion is provided in the vicinity, and a high voltage is applied to the electrode and the protruding portion to form a high-voltage discharge.

[0016] Even with a single electrode, a high-pressure discharge that crosses the rich flame port and the downstream portion of the rich flame port can be reliably formed, and ignition can be reliably performed.

The invention according to claim 5 is one in which the tip of the electrode is particularly sharpened.

Then, the electric field intensity near the tip of the electrode is increased, and a high-pressure discharge crossing the rich flame port and the downstream portion of the rich flame port can be formed more reliably.

According to a sixth aspect of the present invention, there is provided a lean burn port through which the lean mixture flows out, a rich burn port provided near the lean burn port, through which fuel or rich mixture flows, and A rich flame outlet that is provided in close proximity to the rich flame outlet and from which a rich mixture flows out,
It is provided with the rich flame port and a high-temperature heating element positioned so as to cross the downstream portion of the rich flame port.

The high-temperature heating element can be arranged closer to the rich flame port and the rich flame port, and ignition can be performed more reliably.

According to a seventh aspect of the present invention, in particular, the fuel supply amount to the lean burn port is made larger than the sum of the fuel supply amounts to the rich burn port and the rich burn port.

Then, the combustion ratio of a lean flame with a small amount of NOx generated increases, and the combustion ratio of a rich flame and a rich flame with a large amount of NOx generated decreases.
x can be realized.

[0023]

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

(Embodiment 1) FIG. 1 is an enlarged sectional view showing a main part of a combustion apparatus according to Embodiment 1 of the present invention, FIG. 2 is a perspective view showing a burner module of Embodiment 1, and FIG. FGH
It is sectional drawing in a plane.

In FIGS. 1 to 3, reference numeral 50 denotes a thin flame port 51,
This is a burner module having rich flame ports 52a and 52b and rich flame ports 53a and 53b. The rich flame ports 52a, 52b are provided close to each other with the lean flame port 51 therebetween, and the rich flame ports 53a, 53b are respectively provided with the rich flame ports 52a, 52b.
Are provided adjacent to each other. Reference numeral 54 denotes a first electrode whose tip is disposed downstream of the rich flame port 52a, and reference numeral 55 denotes a second electrode whose tip is disposed downstream of the rich flame port 53a.

A plurality of burner modules 50 are arranged in parallel. The burner module 50 is a burner in which a mixture of three different concentrations is burned, that is, a lean burner 56,
Overburners 57a, 57b and overburners 58a, 58
b. A pair of dilute burner forming bodies 59a, 59a, 5b,
9b are overlapped to form a lean burner 56 including a lean flame port 51 and a lean fuel / air inlet 60 into which fuel and air flow into a side portion. The lean flame port 51 divided by the slit 61 is formed. Lean burner forming body 59
Reference numerals a and 59b have steps 62a and 62b, and the width of the lean burner 56 is reduced downstream of the steps.

Next, a pair of dense burner forming bodies 63a and 63b mirror-symmetrical to each other formed by pressing a sheet metal.
Over the outside of the dilute burner forming bodies 59a and 59b, respectively. Rich burner forming body 63a and lean burner forming body 59
a forms a rich burner 57a including a rich flame port 52a and a rich fuel / air inlet 64a into which fuel and air flow. Similarly, the rich burner forming body 63b and the lean burner forming body 59b form a rich burner 57b including a rich flame port 52b and a rich fuel / air inlet 64b.

Next, a pair of dense burner forming bodies 65a, 65 which are formed by pressing a sheet metal and are mirror-symmetrical to each other.
b is put on the outside of the dense burner forming bodies 63a and 63b, respectively. High burner forming body 65a and overburning burner forming body 63
a is a rich burner 58a including a rich flame port 53a and a rich air inlet 66a into which a part of secondary air flows as rich air.
To form Similarly, the rich burner forming body 65b and the overburning burner forming body 63b are formed by the thick flame outlet 53b and the thick air inlet 66.
The burner 58b containing b is formed. The rich burner forming body 63a is provided with a rich mixture dispersion port 67a for communicating the rich burner 57a and the rich burner 58a. Similarly, the rich burner forming body 63b is provided with a rich mixture dispersion port 67b for communicating the rich burner 57b and the rich burner 58b.

A lean fuel outlet 69 provided in the lean nozzle 68 faces the lean fuel / air inlet 60. The rich nozzle 70 is a so-called multi-neck nozzle, and the rich fuel outlet 71 provided in the rich nozzle 70 is provided.
a, 71b are the fuel / air inlets 64a for rich
64b. The gap and the outside of the plurality of burner modules 50 are used as secondary air passages 72.

Next, the operation and operation will be described. First,
At the time of ignition, a fan (not shown) operates, and the lean fuel / air inlet 60, the rich fuel / air inlet 64a, 64
b, air flows in from the thickening air inlets 66a, 66b,
Prepurge of the lean burner 56, the overburn burners 57a and 57b, and the overburn burners 58a and 58b is performed. Next, the first electrode 54
A high voltage is applied between the second electrode 55 and the
a and a high-pressure discharge α crossing the downstream side of the rich flame outlet 53a. Next, fuel is supplied and the lean fuel outlet 6
9. Fuel flows out of the rich fuel outlets 71a and 71b.

The fuel flowing out of the lean fuel outlet 69 and the air supplied by the fan flow into the lean fuel / air inlet 60. The fuel supply amount flowing out from the lean fuel outlet 69 is larger than the sum of the fuel supply amounts flowing out from the rich fuel outlets 71a and 71b. The fuel and air mix in the lean burner 56 to form a lean mixture with a primary excess air ratio greater than 1 (eg, 1.5).

The fuel flowing out of the rich fuel outlets 71a and 71b and the air supplied by the fan flow into the rich fuel / air inlets 64a and 64b, respectively. Fuel and air are mixed in the rich burners 57a and 57b, and a rich mixture is generated in which the primary air excess ratio is smaller than 1 (for example, 0.3).

A part of the rich mixture flowing through the rich burners 57a and 57b is supplied to the rich mixture dispersion ports 67a and 67b, respectively.
b and flows into the dense burners 58a and 58b. Of the air supplied by the fan, air that does not flow into the burner module 50 from the dilution fuel / air inlet 60 and the rich fuel / air inlets 64a and 64b becomes secondary air and flows through the secondary air passage 72. I do. Part of the secondary air flows through the rich air inlets 66a and 66b and flows into the rich burners 58a and 58b, respectively. Then, the rich mixture is diluted with the secondary air, and a rich mixture (primary air excess ratio is, for example, 0.9) is generated.

The lean air-fuel mixture is supplied from the rich flame port 51, the rich air-fuel mixture is supplied from the rich flame ports 52a and 52b, and the rich air-fuel mixture is supplied from the rich flame port 5
It flows out from 3a and 53b, respectively. The high-pressure discharge α ignites the downstream of the rich flame port 52a and the rich flame port 53a, and transfers to all the burner modules 50. After the fire, the application of the high voltage between the first electrode 54 and the second electrode is stopped,
Shift to steady combustion.

The lean mixture flows out of the lean flame port 51 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 outlets 52a and 52b, 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 53a and 53 to form a stable rich flame D, and ignites the rich mixture to generate a rich flame C. Of the secondary air, the secondary air that does not flow into the rich burners 58a, 58b from the rich air inlets 66a, 66b flows out into the combustion space downstream of the burner module 50, and the rich flame D is completely burned by the secondary air. I do.

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 fuel supply ratio of the lean flame A is increased (for example, 90% of the total supply amount), that is, lean, as compared to the conventional so-called lean-burn combustion in which a mixture having two concentrations of a rich mixture and a lean mixture is burned. The amount of fuel supplied to the flame 51 is increased by the rich flames 52a and 52b.
And the fuel supply amount to the rich flame outlets 53a and 53b, and the mixture concentration can be made leaner, and the HC generated from the lean flame A is suppressed while the flame temperature is suppressed. NOx can be realized.

Here, at the time of ignition, a high voltage is applied between the first electrode 54 and the second electrode 55, and between the first electrode 54 and the second electrode 55, the rich flame port 52a and the rich flame port 53a are formed. A high-pressure discharge α is formed across the downstream portion. High pressure discharge α
The rich mixture and the rich mixture flow and diffuse each other.
Regardless of the fluctuation of the excess air ratio due to the fluctuation of the fuel supply amount or the fan rotation speed, the concentration of the air-fuel mixture most likely to ignite (primary excess air ratio is about 0.6 to 0.8) is high in the formation part of the high pressure discharge α. Occurs at any position. For this reason, even if the ratio of the fuel supply amount to the lean flame A is increased, ignition can be reliably performed, and emission of unburned substances such as HC at the time of ignition can be suppressed.

Since two electrodes are arranged, a high-pressure discharge α crossing the downstream of the rich flame port 52a and the rich flame port 53a can be surely formed.

Further, since the tips of the first electrode 54 and the second electrode 55 are sharp, the electric field intensity near the tips of the electrodes increases, and the high-pressure discharge α crossing the rich flame port 52a and the downstream part of the rich flame port 53a. Can be formed more reliably.

The tip of the first electrode 54 is connected to the rich flame port 52b.
The same effect can be obtained by disposing the tip of the second electrode 55 downstream of the rich flame outlet 53b.

(Embodiment 2) FIG. 4 is an enlarged sectional view showing a main part of a combustion apparatus according to Embodiment 1 of the present invention. 4 differs from the configuration of the first embodiment in that the tip of the single electrode 54 is provided downstream of the rich flame port 53a, and the rich flame port 52a and the lean flame port 5 are provided.
This is the point where the protrusion 73 is provided near the boundary of No. 1, that is, near the tip of the electrode 54 in the diluted burner forming body 59a.

Next, the operation and operation will be described. A high voltage is applied between the electrode 54 and the burner module 50. By providing the protruding portion 73, even if it is a single electrode, the high-pressure discharge α that crosses the rich flame port 52a and the downstream portion of the rich flame port 53a.
Can be reliably formed and ignition can be reliably performed.

The tip of the electrode 54 is provided downstream of the rich flame port 53b, and a projection 73 is provided at the boundary between the rich flame port 52b and the lean flame port 51, that is, near the tip of the electrode 54 in the lean burner forming body 59b. The same effect can be obtained.

(Embodiment 3) FIG. 5 is an enlarged sectional view showing a main part of a combustion apparatus according to Embodiment 3 of the present invention. 5 is different from the configuration of the first embodiment in that the tip of the single electrode 54 is provided downstream of the rich flame port 52a, and the boundary of the rich flame port 53a far from the rich flame port 52a, that is, the dense burner. The point is that a protruding portion 73 is provided near the tip of the electrode 54 in the formed body 65a.

Next, the operation and operation will be described. A high voltage is applied between the electrode 54 and the burner module 50. By providing the protruding portion 73, even if it is a single electrode, the high-pressure discharge α that crosses the rich flame port 52a and the downstream portion of the rich flame port 53a.
Can be reliably formed and ignition can be reliably performed.

The tip of the electrode 54 is provided downstream of the rich flame port 52b, and the rich flame port 53 far from the rich flame port 52b is provided.
b, ie, the electrode 5 in the dense burner forming body 65b
The same effect can be obtained even if the protrusion 73 is provided in the vicinity of the tip of the fourth member 4.

(Embodiment 4) FIG. 6 is an enlarged sectional view showing a main part of a combustion apparatus according to Embodiment 4 of the present invention. 6 is different from the configuration of the first embodiment in that the rich flame port 52a and the rich flame port 53 are different.
This is the point that a high-temperature heating element 74 is provided so as to cross the downstream portion of the area a. As an example of the high-temperature heating element 74, there is a ceramic heater that generates heat at a high temperature when energized.

Next, the operation and operation will be described. The first electrode 54 and the second electrode 55 in the first embodiment are
2a, when disposed close to the rich flame outlet 53a, the high-pressure discharge α is not formed between the first electrode 54 and the second electrode 55, and the rich flame from the first electrode 54 (when the second electrode is grounded). Mouth 5
2a, a high-pressure discharge may be formed in the vicinity of the dense flame outlet 53a.

Since the high-temperature heating element 74 is provided so as to cross the rich flame port 52a and the downstream of the rich flame port 53a, the high-temperature heating element 74 is provided at the rich flame port 52a and the rich flame port 53a. It can be arranged closer, and ignition can be performed more reliably.

The same effect can be obtained by providing a high-temperature heating element 74 located across the downstream of the rich flame port 52b and the rich flame port 53b.

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

The configuration of the burner module 50 having a lean flame outlet, a rich flame mouth, and a rich flame mouth is not limited to the structure described in each embodiment. For example, it is also possible to provide a burner module in which a rich flame port is provided adjacent to only one side of the lean flame port and a rich flame port is provided adjacent to the rich flame port, and a plurality of the burner modules may be arranged and used. .

The fuel / air inlets 64a, 6
It is also possible to allow only fuel to flow in from 4b and to allow only fuel to flow out from the rich flame outlet.

[0054]

As described above, according to the first to sixth aspects of the present invention, even if the ratio of the amount of fuel supplied to the lean burn port is increased, the amount of fuel supplied can be reduced to realize ultra-low NOx. Alternatively, ignition can be reliably performed irrespective of fluctuations in the excess air ratio due to fluctuations in the fan speed, and emission of unburned substances such as HC during ignition can be suppressed.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a combustion apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a burner module of the apparatus.

FIG. 3 is a sectional view of a main part of a burner module of the apparatus.

FIG. 4 is an enlarged sectional view of a main part of a combustion apparatus according to a second embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a main part of the apparatus.

FIG. 6 is an enlarged sectional view of a main part of the apparatus.

FIG. 7 is an overall sectional view of a conventional combustion device.

[Explanation of symbols]

 51 Lean Flame Port 52a, 52b Rich Flame Port 53a, 53b Rich Flame Port 54 First Electrode 55 Second Electrode 73 Projection 74 High Temperature Heating Element

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ma Tatemori 1006 Kazuma Kadoma, Kazuma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 3K017 AA01 AA06 AB02 AB07 AB08 AC01 AG02 3K065 TA01 TA04 TA13 TD05 TH04 TP04

Claims (7)

[Claims] 1. A lean burn port through which a lean mixture flows out, a rich burn port provided near the lean burn port, and through which fuel or rich mixture flows out, and a close flame close to the rich burn port. A combustion device comprising: a rich flame port provided with a rich mixture to flow out; and an electrode for forming a high-pressure discharge across the rich flame port and a downstream portion of the rich flame port. 2. The combustion apparatus according to claim 1, wherein the tips of the electrodes are disposed downstream of the rich flame port and the downstream of the rich flame port, respectively. 3. An electrode tip is provided downstream of the rich flame outlet, and a protruding portion is provided near the tip of the electrode at a boundary between the rich flame port and the lean flame port, and a high voltage is applied to the electrode and the protruding portion. The combustion apparatus according to claim 1, wherein the high pressure discharge is formed by applying the high pressure discharge. 4. A tip of an electrode is provided downstream of a rich flame outlet,
The combustion device according to claim 1, wherein a protruding portion is provided near a tip of the electrode at a boundary of the rich flame port far from the rich flame port, and a high voltage is applied to the electrode and the protruding portion to form a high-pressure discharge. . 5. The combustion device according to claim 1, wherein a tip of the electrode is sharpened. 6. A lean flame port through which a lean mixture flows out, a rich flame port provided near the lean flame port, and through which fuel or rich mixture flows out, and a lean flame port near the rich flame port. A combustion apparatus, comprising: a rich flame port provided with a rich mixture to flow out; and a high-temperature heating element positioned to cross the rich flame port and a downstream portion of the rich flame port. 7. The fuel supply amount to the lean burn port is larger than the sum of the fuel supply amounts to the rich burn port and the rich burn port.
The combustion device according to any one of claims 1 to 4.