JPH051804A - Burner of low nox generation - Google Patents

Abstract

PURPOSE:To provide measures to reduce the volume of generated NOx without increasing noises in a small size burner such as used for households, small scale businesses, etc. CONSTITUTION:A flame port plate 3 with a countless number of minute holes 2 is provided on the downstream side of a first mixture gas chamber 1 and at the same time on the upstream side from the flame port plate 3 in the first mixture gas chamber 1 a second mixture gas chamber 4 is provided. It has many projecting blow-out pipes 5 and their top ends are in contact with the above-mentioned flame port plate 3 and, at the same time, on the flue port plate 3 a flame port 6 is formed which corresponds to the blowout pipes 5 respectively. A mixture gas in which the fuel proportion is low is supplied to the first mixture gas chamber 1 and at the same time a mixture gas in which the fuel proportion is high is supplied to the second mixture gas chamber 4 and a combustion is carried out. Then the flame by the low fuel concentration mixture gas is stabilized and it is possible to have combustions of the high fuel concentration and the low fuel concentration, and with these thick and thin combustions noises are not increased and the volume of the generated NOx can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-nitrogen-oxide generating burner used in a small-sized combustion device for household use, small-sized business use, or the like.

[0002]

2. Description of the Related Art Nitrogen oxides (NOx) in the combustion gas of burners in various combustors are considered to be one of the causes of acid rain and photochemical smog, as well as being toxic by themselves. The burner used in the equipment has this NO
Various measures have been developed and taken to reduce the generation amount of x.

[0003]

However, these countermeasures have hitherto been mainly applied to a large-scale combustion apparatus for industrial use, which is legally regulated, and it has a small size for domestic use or small-scale business use. Since the combustion device has problems such as noise, it cannot be said that sufficient measures are taken. That is, in a large-scale combustion device, since the static pressure of the combustion fan can be increased, it is easy to control the flow of combustion gas and air, the degree of freedom in the burner layout is high, and noise countermeasures are also easy. Due to such advantages, the conditions for countermeasures against noise are not strict, and since the combustion chamber can be made large, there is an advantage that it is easy to complete combustion even if measures to reduce NOx by so-called slow combustion are taken, whereas it is small. No such combustion device has these advantages, and therefore, a small combustion device is difficult to take measures for NOx reduction as compared with a large combustion device. An object of the present invention is to solve the above-mentioned conventional problems by rationally applying so-called light and dark combustion to a small-sized combustion device.

[0004]

Means for solving the above-mentioned problems will be described with reference to the drawings corresponding to the embodiments. A low-nitrogen-oxide generating burner according to the present invention comprises a first air-fuel mixture chamber. 1. A flame hole plate 3 provided with innumerable minute flame holes 2 is installed on the downstream side of 1, and the flame hole plate 3 in the first mixture chamber 1 is installed.
A second air-fuel mixture chamber 4 is installed on the upstream side, and a large number of ejection pipes 5 are provided in the second air-fuel mixture chamber 4 so as to abut the tips thereof on the flame hole plate 3. The flame hole plate 3 is formed with flame holes 6 corresponding to the respective ejection pipes 5 to supply a fuel-lean air-fuel mixture to the first air-fuel mixture chamber 1 and to the second air-fuel mixture chamber 4. It is configured to supply a fuel-rich mixture. In the above configuration, the second air-fuel mixture chamber 4 is installed so as to form a air-fuel mixture circulation space between the second air-fuel mixture chamber 1 and the wall of the first air-fuel mixture chamber 1, and the second air-fuel mixture chamber 1 is mixed with the air-fuel mixture. The air is supplied from the upstream side of the installation position of the second air-fuel mixture chamber 4, and the air-fuel mixture is supplied to the first air-fuel mixture chamber 1 by the installation of the second air-fuel mixture chamber 4. The configuration may be performed from the downstream side of the position. Further, the second air-fuel mixture chamber 4 may be divided into a plurality of parts and installed in the first air-fuel mixture chamber 1 to form the air-fuel mixture circulation space 7 between the second air-fuel mixture chambers 4. it can.

[0005]

In the above structure, the fuel-lean air-fuel mixture supplied into the first air-fuel mixture chamber 1 is ejected from the innumerable minute flame holes 2 provided in the flame hole plate 3 on the downstream side thereof. To burn. Since this combustion is subdivided combustion and combustion of excess air, the cooling action of excess air maintains the temperature of the flame at a low temperature and reduces the generation of NOx. On the other hand, the fuel-rich air-fuel mixture supplied into the second air-fuel mixture chamber 4 is discharged from the ejection pipe 5
Is ejected through the flame holes 6 of the flame hole plate 3 and burned. Since this combustion is performed in a state where the oxygen partial pressure is low, NOx
It suppresses the generation of and forms a stable flame.

Combustion of excess air by a fuel-lean mixture has poor flame stability by itself. However, adjacent flames are mixed with stable flames by the above-mentioned rich fuel mixture. As such, these stable flames act as a pilot flame to stabilize the excess air flame.
Therefore, the lift of the flame and the oscillating combustion do not occur, and the generation of noise is suppressed. Further, the fuel-lean air-fuel mixture ejected from the minute flame holes 2 acts to supply secondary air to the flame of the fuel-rich air-fuel mixture, and incomplete combustion of the fuel-rich air-fuel mixture occurs. Occurrence of combustion can be prevented.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.
First, FIGS. 1 to 3 show an embodiment of the present invention, in which reference numeral 1 is a first air-fuel mixture chamber, and a flame hole plate 3 provided with innumerable minute flame holes 2 is provided on the downstream side thereof. ing. A second air-fuel mixture chamber 4 is installed in the first air-fuel mixture chamber 1 on the upstream side of the flame hole plate 3. A large number of ejection pipes 5 are provided in a projecting manner in the second air-fuel mixture chamber 4, and their tips are connected to the flame hole plate 3
And the flame hole plate 3 is formed with flame holes 6 corresponding to the respective ejection pipes 5. This second mixture chamber 4
Is installed so as to form a mixture air circulation space 7 with the wall of the first mixture chamber 1. Further, the air-fuel mixture introducing chamber 8 is formed adjacent to the first air-fuel mixture chamber 1, and the first air-fuel mixture introducing portion 9 corresponding to the first air-fuel mixture chamber 1 and the second air-fuel mixture chamber 4, respectively. , The second air-fuel mixture introducing section 10 is configured. The first air-fuel mixture introducing unit 9 is configured to directly introduce the fuel-lean air-fuel mixture mixed by an appropriate mixing device into the first air-fuel mixture chamber 1, and the second air-fuel mixture introducing unit 10 is A fuel gas jetting portion 13 is provided toward the air-fuel mixture inlet 12 having the mixing throat portion 11. The specific configuration of the air-fuel mixture introducing units 9 and 10 can be appropriately configured in addition to the above-described configuration.

In the above structure, the fuel-lean air-fuel mixture supplied from the first air-fuel mixture introducing portion 9 to the first air-fuel mixture chamber 1 passes through the air-fuel mixture distribution space 7 and a large number of jets. Tube 5
It reaches the flame hole plate 3 through the gap between them, and ejects from the numerous minute flame holes 2 formed in this flame hole plate 3. On the other hand, the rich fuel-air mixture supplied from the second air-fuel mixture introducing section 10 to the second air-fuel mixture chamber 4 reaches the flame plate 3 through the ejection pipe 5, and the flame formed in the flame plate 3 is discharged. Eject from the hole 6. In this way, the fuel-lean air-fuel mixture is ejected from the innumerable minute flame holes 2 of the flame hole plate 3, and the fuel-rich air-fuel mixture is emitted from the flame holes 6 mixedly formed in the minute flame holes 2. It is jetted and burned. Combustion by a fuel-lean air-fuel mixture ejected from the innumerable minute flame holes 2 is not only fragmented combustion but also combustion of excess air, so that the temperature of the flame is kept low by the cooling action of excess air and NOx Is reduced. On the other hand, since the combustion by the rich fuel-air mixture ejected from the flame holes 6 mixed with the minute flame holes 2 is performed in a state where the oxygen partial pressure is low, the generation of NOx is also suppressed and a stable flame is generated. Form.

Combustion of excess air by a fuel-lean mixture has poor flame stability by itself, but stable flames due to the above-mentioned fuel-rich mixture are mixed adjacent to these flames. As such, these stable flames act as a pilot flame to stabilize the excess air flame.
Therefore, the lift of the flame and the oscillating combustion do not occur, and the generation of noise is suppressed. Further, the fuel-lean air-fuel mixture ejected from the minute flame holes 2 acts to supply secondary air to the flame of the fuel-rich air-fuel mixture, and incomplete combustion of the fuel-rich air-fuel mixture occurs. Occurrence of combustion can be prevented.

In the above structure, the first air-fuel mixture chamber 1
The air-fuel mixture is supplied to the upstream side of the installation position of the second air-fuel mixture chamber 4, but as shown in FIG. 5, the air-fuel mixture is supplied from the downstream side of the second air-fuel mixture chamber 4. You can also Further, in the above structure, the second air-fuel mixture chamber 4 is shown in FIG.
As shown in FIG. 2, the air-fuel mixture can be divided into a plurality of parts and installed in the first air-fuel mixture chamber 1, and the air-fuel mixture circulation space 7 can be provided between the second air-fuel mixture chambers 4. Further, if a plurality of second air-fuel mixture chambers 4 are installed in this manner and the air-fuel mixture can be independently supplied, combustion can be switched.

FIG. 6 shows an example of the result of carrying out the present invention. As a result of this implementation, in the burner shown in FIGS. 1 to 3, the air ratio of the fuel-rich mixture is expressed by λ = 0.7 to 0.
75 or λ = 0.65 is set, and the amount of NOx generated when combustion is performed by adjusting the air ratio of the fuel-lean mixture so that the overall air ratio becomes the value shown on the horizontal axis in the figure. It is a representation. In the burner corresponding to the result of this implementation, the individual diameters of the fine flame holes 2 and the flame holes 6 are φ.
1.2 and φ3.0, the ratio of the sum of total flame hole areas to the area of the flame hole plate 3 is approximately 1: 4.7, and the sum of the flame hole area of the minute flame holes 2 and the flame hole 6 is The ratio to the sum of the flame area is approximately 1:
It is set to 1.3. In this structure, the ratio of the combustion amount of the fuel-lean mixture to the combustion amount of the fuel-rich mixture is 7: 3. Of course, it goes without saying that these values can be set appropriately. As shown in FIG. 6, it can be seen that the burner of the present invention having the above-described configuration has a significantly reduced amount of NOx produced as compared with the conventional premixed burner. In addition, the burner of the present invention produced lower noise than the conventional premix burner.

[0012]

As described above, according to the present invention, the fuel-lean air-fuel mixture and the fuel-rich air-fuel mixture are rationally mixed and ejected from the flame plate to perform rich-fuel combustion. By reasonably coexisting the effect of reducing the amount of NOx generated by combustion of a rich air-fuel mixture and the effect of reducing the amount of NOx generation by a fuel-lean air-fuel mixture, the stability of the flame in the latter combustion is improved. In addition to suppressing the generation of noise, it is possible to prevent the generation of incomplete combustion in the former combustion, and generate NOx without increasing noise in a small-sized combustion device that requires severe measures against noise. There is an effect that a measure for reducing the amount can be taken.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view corresponding to a first embodiment of the present invention.

FIG. 2 is an explanatory vertical cross-sectional view taken along line XX of FIG.

FIG. 3 is an explanatory vertical sectional view taken along the line YY of FIG.

FIG. 4 is an explanatory longitudinal sectional view showing another embodiment of the present invention cut at the same position as in FIG.

5 is an explanatory longitudinal sectional view showing a further embodiment of the present invention cut at the same position as in FIG.

FIG. 6 is an explanatory diagram showing the NOx generation amount of the burner of the present invention in comparison with a conventional premix burner.

[Explanation of symbols]

1 First air-fuel mixture chamber 2 Micro flame holes 3 flame plate 4 Second mixture chamber 5 Spout pipe 6 flame holes 7 mixture distribution space 8 Mixture introduction chamber 9 First mixture introduction section 10 Second mixture introduction section 11 Mixing throat 12 Mixture inlet 13 Fuel gas ejection part

Continued front page    (72) Inventor Kimio Mochizuki             No. 201 Nishi-Kashiwabara Shinden, Fuji City, Shizuoka Prefecture Takagi             Business (72) Inventor Shigetoshi Akiyama             No. 201 Nishi-Kashiwabara Shinden, Fuji City, Shizuoka Prefecture Takagi             Business

Claims (4)

[Claims] 1. A flame hole plate having innumerable minute flame holes is installed on the downstream side of the first air-fuel mixture chamber, and a second air hole plate is provided on the upstream side of the flame hole plate in the first air-fuel mixture chamber. An air-fuel mixture chamber is installed, and a large number of ejection pipes are provided in the second air-fuel mixture chamber so that the tips of the ejection pipes are brought into contact with the flame hole plate. And a fuel-lean air-fuel mixture is supplied to the first air-fuel mixture chamber and a fuel-rich air-fuel mixture is supplied to the second air-fuel mixture chamber. Nitrogen oxide low generation burner 2. The second air-fuel mixture chamber according to claim 1 is installed so as to form an air-fuel mixture circulation space between the second air-fuel mixture chamber and the first air-fuel mixture chamber wall, and the air-fuel mixture to the first air-fuel mixture chamber is set. A low-nitrogen-oxide-generating burner characterized by being configured so that the supply of air is performed from the upstream side of the installation position of the second mixture chamber. 3. The second air-fuel mixture chamber according to claim 2, wherein the second air-fuel mixture chamber is divided into a plurality of parts and is installed in the first air-fuel mixture chamber to form a air-fuel mixture circulation space between the second air-fuel mixture chambers. A low-nitrogen oxide generation burner characterized by 4. A low nitrogen oxide content according to claim 1, wherein the supply of the air-fuel mixture to the first air-fuel mixture chamber is performed from the downstream side of the installation position of the second air-fuel mixture chamber. Fire burner