JPH03113202A - Low nox bunsen burner - Google Patents

Abstract

PURPOSE:To reduce the generation of NOx and stabilize a flame by projecting a burner port member constituting the burner port part of a burner and made of wire-netting and the like so as to be formed into a substantially angular shape, covering the burner port member with a stable-flame holding plate having alternately stable-flame holding parts and cutting parts, along the longitudinal direction of the burner, forming main burner ports divided respectively at the cutting parts, and forming auxiliary burner ports at the stable-flame holding parts. CONSTITUTION:Primary air is induced into a Venturi tube 4 by the jet of gas supplied from a nozzle 2 to be converted into a mixed gas which is supplied to a burner port part 6 after being evenly distributed by a strainer 5. A primary flame 14 is formed above the burner port part 6 by combustion, and a secondary flame 15 is formed above the primary flame 14. A high-temperature zone is usually formed in the secondary flame 15 as is well-known; however, since secondary air 16 is supplied deep into the central part of the secondary flame 15, as shown by the arrow, along the inclination of a burner port member 7 by projecting the burner port member 7 so as to be formed into a substantially angular shape and by partitioning a main burner port 11 with stable-flame holding parts 8, the formation of the high-temperature zone can be prevented. In addition, since a small amount of the mixed gas is supplied to auxiliary burner ports 12 provided on the stable-flame holding parts 8, the fuel is burnt at an early stage in a small flame, and since the combustion gas generated thereby is supplied to the flame formed on the main burner ports, a temperature in the high- temperature zone is further lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a Bunsen burner used in household heaters, water heaters, and the like.

2. Description of the Related Art A Bunsen burner according to the prior art ejects gaseous fuel or gasified fuel from a nozzle, uses the ejection energy to suck in primary air, and supplies it as a so-called premixed combustible gas to a flame opening for combustion. This product has high combustion efficiency, so the flame reaches a high temperature, and nitrogen oxides (hereinafter referred to as N) in the air are
The disadvantage is that the concentration of OX (referred to as OX) is high.

For example, if natural gas (CH4) is diluted with -2 air, 8.7
FIG. 6 shows an example of the flame temperature distribution when a combustible mixture with a concentration of % natural gas is combusted.

As shown in the figure, the temperature at the center 15 of the secondary flame is much higher than that at the center 14 of the primary flame, and the high temperature region exceeding 1800° C. is extremely wide. The reason for this is that because of the premixed gas, the mixture ratio is close to the stoichiometric mixture at the center of the flame, indicating that sufficient combustion is possible even without the supply of secondary air from outside the flame.

Therefore, in order to reduce NOx, a) excessive secondary air is supplied to the high temperature region to lower the flame temperature.

b. Shorten the nitrogen oxidation reaction time by narrowing the high temperature region.

These two points are the technical points for reducing NOx.

Below, we will specifically extract problems with typical conventional techniques.

(1) Japanese Utility Model Application Publication No. 54-165335 discloses a burner in which the flame opening portion of the burner is divided into four parts in the column direction and four parts in the longitudinal direction.

Considering this as a single burner port, the length of the burner port is extremely large compared to the length of the non-flame port in the longitudinal direction of the burner.

Due to this flameless port length, some secondary air is supplied between adjacent flame ports, but because the flame port length is large, the flame temperature distribution at the center of the flame port becomes close to the distribution shown in Figure 6. There is.

Further, since the wire gauze mouth is flat, the flow rate of secondary air supplied from the non-flame mouth part is small.

Furthermore, since there is no flame holding plate, the flame tends to become unstable when combustion is low.

(2) Japanese Utility Model Application No. 55-153427 discloses a burner in which the flame opening portion of the burner is divided into four parts in the longitudinal direction and four parts in the row direction.

This specific example also has the same structure as the above-mentioned Japanese Utility Model Publication No. 54-165335, and has exactly the same drawbacks.

(3) Japanese Utility Model Application Publication No. 57-30535 discloses a burner which is divided into a large number of burners in the longitudinal direction and into two in the column direction.

The first drawback of this method is that, like the above-mentioned one, since the flame opening surface is flat, the supply of secondary air is insufficient, the flame temperature becomes high, and NOx is generated in large quantities.

The second drawback is that the flame tends to become unstable during low combustion because there is no flame holding plate.

The third drawback is that the distance between the flame ports in the row direction is long, so the flame transfer in the row direction is poor. Therefore, it is necessary to provide a fire transfer structure using other members.

(4) Japanese Utility Model Application Publication No. 59-18124 discloses a burner in which the burner port is divided into two in the row direction and into five in the longitudinal direction, and auxiliary burner ports are provided at both ends.

The first drawback of this is the above-mentioned Utility Model Application No. 54-165335
Similar to the publication, the length of the flame opening is long and the length of the flameless opening is short. This increases the flame temperature and increases the amount of NOx produced.

The second drawback is that the secondary air is supplied from the outside of each flame port when viewed in the row direction, and the supply from the inside is almost nil. In other words, as a result of expanding the high temperature region shown in FIG. 10, the amount of NOx generated increases.

Problems to be Solved by the Invention As mentioned above, the conventional technology generates a lot of NOx.

Therefore, the object of the present invention is to obtain a Bunsen burner that reduces the generation of NOX and improves flame stability at the same time.

Means for Solving the Problems In order to solve the above problems, in the present invention, a burner mouth body such as a wire mesh constituting the burner mouth part is protruded in a substantially mountain shape, and a burner is attached to the protruding burner mouth body along the longitudinal direction of the burner. A flame stabilizing plate having alternating flame stabilizing parts and notches is placed over the flame stabilizing plate, and divided main flame ports are formed in each of the notches, and auxiliary flame ports are formed in the flame stabilizing parts.

Further, this auxiliary flame port is formed by a plurality of circular holes or slits.

The fuel used in the Bunsen burner is of extremely high quality because the fuel itself does not contain nitrogen.

Therefore, all NOx produced by combustion is produced by the oxidation of nitrogen in the air. So-called thermal NOX
It is.

In the present invention, the flame port protrudes in a substantially mountain shape and is divided along the longitudinal direction to improve the supply of secondary air into the flame, and by having an auxiliary flame port in the main flame part. The temperature in the high humidity part of the flame is lowered, the flame stabilizer plate is used to stabilize the flame in the low combustion range, and the time for oxidation of nitrogen is shortened to reduce NOx.

In addition, a small flame is formed at the auxiliary flame port, and combustion is completed early, and the combustion gas is supplied to the flame formed above the main flame port, further lowering the temperature in the high temperature area and reducing NOx. It can be measured.

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

In the figure, 1 is a fuel pipe, 2 is a nozzle, and 3 is a burner body. The burner body 3 includes a venturi 4 whose base end opening faces the tip of the nozzle 2, a strainer 5 provided at the outlet of the venturi 4 for evenly distributing the mixed gas, and a strainer 5 formed on the upper surface of the burner body 3. It is formed by a burner port 6 that is The flame mouth part 6 is made of wire mesh or perforated steel plate, etc., and includes a flame mouth body 7 whose center part protrudes in an almost chevron shape, flame holding parts 8 and notches 9 arranged alternately along the longitudinal direction like a ladder. The flame plate 10 and this flame holding plate l
By tightly covering the upper surface of the burner port body 7 with O, a main burner port 11 divided into each notch portion 9 is formed.

The flame holding portion 8 is also provided with a plurality of (four in the figure) auxiliary flame ports 12 made of circular holes or slits, in which small flames are formed.

Furthermore, the width of the main flame opening and the width E of the flame holding part 8 are E/D=0.
．． 2 or more, and when the radiation E of the flame holding part 8 is increased, the center of the flame holding part 8 is cut out to provide a flame port 13 for flame transfer, as shown in FIGS. 2 and 5.

Next, its operation will be explained.

The fuel supplied from the fuel pipe 1 becomes a jet from the nozzle 2 and is supplied to the venturi 4. The primary air is sucked into the venturi 4 by the gas jet and becomes a mixed gas, which is evenly distributed by the strainer 5. Tanochi flame mouth part 6
is supplied to A primary flame 14 is generated on the flame bottom part 6 due to combustion.
is generated, and a secondary flame 15 is formed above it.

As is well known, a high temperature region is formed within the secondary flame 15, so it is necessary to quickly supply secondary air 16 into this region to prevent the temperature from rising.

In the present invention, the burner port body 7 protrudes in a substantially mountain shape, and the main burner port 1
1 is partitioned by the flame holding part 8, the secondary air 16 is supplied deep into the center of the flame along the slope of the flame port body 7 as shown by the arrow, thereby preventing the formation of the above-mentioned high temperature region. can.

In addition, since a small amount of mixed gas is supplied to the auxiliary flame port 12 on the flame holding part 8, combustion of the fuel is completed early with a small flame, and CO
3. Gases such as H and O having relatively large specific heats are mixed with the generated flame at the afterburner port 11, resulting in a so-called self-exhaust gas recirculation effect, which promotes lowering the temperature of the secondary flame.

Furthermore, since the flame port 13 for flame transfer is provided at the top of the flame holding part 8, the flame transfer is facilitated.

Effects of the Invention The first effect of the present invention is that the generation of a high temperature region within the secondary flame can be prevented, thereby significantly reducing the amount of thermal NOX generated.

The second effect of the present invention is that a stable flame can be formed by the flame stabilizing part and the auxiliary flame port, so that the good combustion range can be further expanded.

The third effect of the present invention is that secondary air is supplied from above the flame holding part, which improves the diffusion of secondary air within the flame, reduces the limit of red flame (luminous flame) generation, and creates a good combustion zone. Can be expanded.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a Bunsen burner according to the present invention, Fig. 2 is a parent view of A in Fig. 1, Fig. 3 is a sectional view taken along line B-B in Fig. 2, and Fig. 4 is a cross-sectional view taken along line C-C in Fig. 2. 5 is a perspective view of the flame nozzle according to the present invention, and FIG. 6 is a typical temperature distribution diagram of a Bunsen burner flame. In the figure, 3 is the burner main body, 6 is the burner port, 7 is the burner port, 8 is the flame holding part, 9 is the notch, 10 is the flame holding plate, 11 is the main burner port, and 12 is the auxiliary burner port. .

Claims (2)

[Claims] (1) A Bunsen burner in which gaseous fuel or gasified fuel is ejected from a nozzle (2), primary air is sucked in by the ejection energy, and is burned as a premixed combustible gas at a flame port (6). The burner has a flame mouth body (7) such as a wire mesh projecting from the flame mouth part (6) in a substantially chevron shape, and has flame holding parts (8) and cutout parts (9) alternately along the longitudinal direction of the burner, It consists of a flame holding plate (10) placed over the flame mouth body (7), a main flame mouth (11) is formed in the notch (9), and an auxiliary flame mouth (12) is formed in the flame holding part (8). Low NOX formed by
Bunsen burner. (2) The low NOx Bunsen burner according to claim 1, wherein the auxiliary flame port (12) of the flame holding part (8) is formed by a plurality of circular holes or slits.