JPH04151417A - Low nox burner - Google Patents

Abstract

PURPOSE:To prevent ignition and reduce NOX by forming a second mixing gas chamber communicating with a mixing gas chamber of a main body with a side board which comprises a slanting section having an air intake port and connecting its lower end with the main body and a parallel section in parallel to the main body outside the burner main body in a captioned Bunsen burner. CONSTITUTION:A side board is mounted to a burner main body 11 on both sides, thereby forming a second mixing gas chamber 14 where the side board comprises a slanting section which forms an air intake port 2 and a parallel section placed in parallel to the main body 11. The side board is communicated with a mixing gas chamber of the main body 11 by way of a mixed gas passage 13. In this construction, a part of the mixed gas in the burner main body 11 is ejected from a flame port 12 while the rest is introduced into a second mixing chamber from the mixed gas passage 13. Air is introduced from an air intake port 22 so as to produce a mixed gas which fails to exceed a flammable limit and the mixed gas is ejected from a flame port 18. Since the intake port 22 is designed to form a slanting section for the ejection, an intake area is increased, which makes it possible to dilute the mixed gas to a satisfactory content and hence reduce the generation of NOX.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a Bunsen type low NOx burner.

2. Description of the Related Art A conventional Bunsen type low NOx burner for household use, for example, as shown in FIG. A second mixture chamber 5 having a second flame port 4 provided on both sides of the first mixture chamber 3 is connected to the first mixture chamber 3 and the second mixture chamber 5. A mixture passage 6 provided in the burner body 2 to pass through the burner, and an air intake lower formed at the horizontal bottom of the second mixture chamber 5 to set the primary air ratio of the second mixture chamber 5. things are known. In such a configuration, combustion is slowed down by supplying the unburned air-fuel mixture with a low oxygen concentration ejected from the second flame port 4 to the flame formed on the first flame port 1. , attempts were made to lower the flame temperature and reduce the generation of thermal NOx.

Problems to be Solved by the Invention However, in the above configuration, since the air intake lower is formed at the horizontal bottom of the second air-fuel mixture chamber 5, the area of the air intake lower cannot be increased. ,
There was a problem in that the mixture in the second mixture chamber 5 could not be sufficiently diluted to below the flammability limit, causing flame to move to the mixture passage 6.

The present invention is intended to solve these problems, and aims to prevent unnecessary fire transfer and reduce the generation of NOx.

Means for Solving the Problems In order to solve the above problems, the low NOx burner of the present invention has the following features:
A first mixture chamber provided in the burner body having a first flame port, and a second flame port formed at the upper end between a side plate attached to the outer surface of the burner body and the outer surface of the burner body. a second air-fuel mixture chamber having an air-fuel mixture; a air-air mixture passage provided in the burner body to communicate the first air-fuel mixture chamber and the second air-fuel mixture chamber; and an air intake for setting the primary air ratio of the second air mixture chamber,
The lower end and both horizontal ends of the side plate forming the second air-fuel mixture chamber are connected to the burner body, and the side plate has an inclined portion upward from the lower end and a top end of the inclined portion that connects to the upper end of the burner main body. The air intake port is provided with a parallel portion parallel to the outer surface, and the air intake port is formed in the inclined portion.

According to the present invention, the area of the air intake port can be made larger than that of the conventional one, and the secondary air flowing between the burners can be sufficiently supplied from the air intake port to the second air mixture chamber. Therefore, the mixture in the second mixture chamber is sufficiently diluted to below the flammability limit and is supplied from the second flame opening to the flame formed above the first flame nozzle as a mixture with a lower oxygen concentration than the atmospheric oxygen concentration. This slows combustion and lowers the flame temperature.

Further, by sufficiently diluting the air-fuel mixture in the second air-fuel mixture chamber compared to the prior art, it is possible to prevent fire from transferring to the air-fuel mixture passage.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings.

In FIG. 1 and FIG. 2, 11 is a burner main body, which is provided with a first air-fuel mixture chamber 23 inside, and this burner main body 1
A first flame opening portion 12 having a plurality of slit-like openings is formed on the upper surface of the burner 1 . Further, mixture passages 13 are provided on both sides of the burner body 11 at appropriate intervals in the longitudinal direction.
Furthermore, the burner body 11 is provided on the outer surface of both sides of the burner body 11.
A side plate 15 is attached that forms a second air-fuel mixture chamber 14 between the side plate 15 and the outer surface of the first air-fuel mixture chamber 14 . Upper end 16 of the side plate 15
A second flame port 18 is formed between the upper end portion 17 of the burner body 11 and the upper end portion 17 of the burner body 11 . The lower end 19 and both horizontal ends of the side plate 15 are fixed to the burner body 11, and the side plate 15
has an inclined part 20 upward from the lower end, and this inclined part 20.
A parallel part 21 connected to the upper end and parallel to the outer surface of the burner body 11 is provided, and the inclined part 20 has an air intake port 22.
are provided at appropriate intervals in the longitudinal direction of the burner body 11.

Note that in an actual combustion apparatus, a plurality of burners having the above configuration are provided, and the secondary air ports 24 are formed at appropriate intervals between the upper ends of adjacent burners.

Here, the principle of generation of NOx generated from flame will be explained. NOx generated from flame is generally fuel NO
There are x and thermal NOx, and the amount of fuel NOx generated depends on the type of fuel. Thermal NOx is NOx produced by reaction of N2 in the air when passing through a flame reaction zone, and the amount of thermal NOx generated is determined by the temperature of the flame reaction zone. Note that the amount of thermal NOx generated decreases as the temperature of the flame reaction zone decreases. Therefore, when a flame is burned in an atmosphere with a low oxygen concentration, the reaction becomes slow and the flame reaction zone becomes large, so that the amount of heat generated per unit flame reaction zone decreases. For these reasons, the temperature of the flame reaction zone is lowered, and NOx can be reduced.

In the combustion method of the burner of this embodiment, an unburned air-fuel mixture ejected from the second flame port 18 and having a lower oxygen concentration than the atmosphere is supplied to the flame formed on the first flame port 12. This slows down the combustion reaction of the flame formed in the burner body 11, lowers the flame temperature, and reduces the generation of thermal NOx.

In the above configuration, the primary air ratio of the mixture inside the first mixture chamber 23 is set to 30 to 60%.

A part of this air-fuel mixture is ejected from the first flame port 12, and the remaining air-fuel mixture passes through the air-fuel mixture passage 13 and enters the second air-fuel mixture chamber 14.
After that, the mixture is mixed with the air entering from the air intake port 22, and the mixture becomes a mixture with a primary air ratio of about 170 to 250% and below the combustible limit, and is ejected from the second flame port 18. . The secondary air flows between adjacent burners from the bottom to the top, a part of which flows into the second air mixture chamber 14 through the air intake port 22, and the rest flows along the outer periphery of the side plate 15 into the secondary air port 24. Therefore, the amount of air flowing into the second mixture chamber 14 is determined by the ratio of the areas of the air intake port 22 and the secondary air port 24. Since a large amount of air is required to bring the mixture in the second mixture chamber 14 below the flammable limit,
The area of the air intake 22 must be significantly larger than the area of the secondary air opening 24. Therefore, air intake 2
2 is provided on the inclined part 20 instead of on the horizontal bottom part as in the conventional burner, and the area of the air intake port 22 can be made larger than that in the conventional burner. This allows the fuel to be sufficiently diluted to below the combustible limit, prevents unnecessary transfer of fire to the second air-fuel mixture chamber 14, and reduces the generation of NOx using the above-mentioned original combustion method.

Further, the air flowing through the secondary air port 24 is transferred to the second flame port 18.
After being supplied as the secondary air of Complete combustion and prevent generation of unburned gas.

Effects of the Invention As described above, the low NOx burner of the present invention provides the following effects.

(1) By expanding the area of the air intake that sets the primary air ratio of the second mixture chamber, the mixture in the second mixture chamber can be sufficiently diluted to below the flammable limit, and the second mixture This prevents unnecessary flame transfer into the air chamber, and supplies the unburned mixture with low oxygen concentration ejected from the second flame port to the flame formed above the first flame port to lower the flame temperature. By decreasing, N
The original combustion method that reduces the generation of Ox can be realized.

(2) Further, since the secondary air flowing around the burner surrounds the air-fuel mixture ejected from the second flame port and completely burns it, no unburned gas is generated.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional perspective view of a low NOx burner according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the same burner, and FIG. 3 is a cross-sectional perspective view of a conventional low NOx burner. DESCRIPTION OF SYMBOLS 11... Burner main body, 12... First flame opening part, 13
...Mixture passage, 14...Second mixture chamber, 15.
...Side plate, 16.17...Top end, 18...Second flame port, 19...Lower end, 20...Slanted part, 21.
...Parallel portion, 22...Air intake port, 23...First air mixture chamber, 24...Secondary air port. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. A first air-fuel mixture chamber provided in the burner body having a first flame port, and a second flame formed at the upper end between a side plate attached to the outer surface of the burner body and the outer surface of the burner body. a second mixture chamber having a mouth; a mixture passage provided in the burner body to communicate the first mixture chamber and the second mixture chamber; and the second mixture chamber. and an air intake for setting the primary air ratio of the second air mixture chamber, and connects the lower end and both horizontal ends of the side plate forming the second air mixture chamber to the burner main body. and the side plate is provided with an inclined part upward from the lower end and a parallel part connected to the upper end of the inclined part and parallel to the outer surface of the burner main body,
A low NO_x burner, wherein the air intake port is formed in the inclined portion.