JP2768391B2 - Low NOx burner - Google Patents

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 burner used in a small-sized combustion device for home use, small business use, and the like.

[0002]

2. Description of the Related Art Nitrogen oxides (NOx) in the combustion gas of a burner in various combustion apparatuses are considered to be not only toxic to themselves but also one of the causes of acid rain and photochemical smog. The burner used for the device has this NO
Various measures have been developed and taken to reduce the amount of x generation.

[0003]

However, in the past, these measures have been mainly applied to large-scale combustion devices for industrial use and the like, which are legally regulated, and have been adopted for small-sized combustion devices for home use and small business use. Combustion devices do not always take sufficient measures due to problems such as noise.

That is, in a large-sized combustion device, the static pressure of the combustion fan can be increased, so that the flow of combustion gas and air can be easily controlled, the layout of the burner has a high degree of freedom, and noise control is also taken. With advantages such as simplicity,
Since the conditions for measures against noise are not severe and the combustion chamber can be made large, there is an advantage that complete combustion is easy even if so-called slow NOx reduction measures are taken. A combustion apparatus configured to obtain a large amount of combustion does not have these advantages, and it is difficult to reduce NOx as compared with a large combustion apparatus. An object of the present invention is to increase the mounting density of a burner so that a large amount of combustion can be obtained, and to stably perform combustion with a fuel-lean mixture to reduce nitrogen oxides and noise. The purpose is to achieve it.

[0005]

Means for solving the above-mentioned problems will be described with reference to the drawings corresponding to the embodiments. The present invention provides a low-nitrogen oxide generating burner according to the present invention. A plurality of first and second burner units, which constitute a flame hole at the upper part of the body and a fuel gas and air introduction part at the side of the lower part and constitute a mixing pipe part from the introduction part to the flame hole, The first burner unit is arranged alternately in a row, and the first burner unit is configured such that the introduction portion is located below the introduction portion of the second burner unit and has a large diameter so that a larger amount of fuel gas and air can be supplied. The first and second burner units are provided with fuel gas ejection portions corresponding to the respective introduction portions, and the first burner unit is provided with a fuel-lean,
In addition, an air-fuel mixture in which the amount of fuel gas is larger than the amount supplied to the second burner unit is supplied, and a fuel-rich air-fuel mixture is supplied to the second burner unit.

In the above configuration, the burner body has an upper portion having a small thickness and a lower portion having a large thickness, a flame hole portion is formed at an upper end of the upper portion, and an introduction portion is formed at a lower portion. The mixing tube section may be configured so that the lower part of the second burner unit corresponds to the upper part of the first burner unit.

[0007]

In the first burner unit, the fuel gas and air introduction sections are located below the introduction section of the second burner unit, and these introduction sections are configured in two levels. These first and second burner units can be arranged at high density by alternately arranging them. At this time, the upper part constituting the flame hole of the first burner unit is formed thinner than the lower part constituting the introduction part and the mixing pipe part, and the second burner is disposed adjacent to these upper parts. If the lower portion of the unit is configured to correspond, a higher-density row can be provided.

[0008] Further, with the above configuration, the distance from the introduction portion of the first burner unit to the flame hole is longer than that of the second burner unit, so that the fuel gas and the air can be mixed well. . Therefore, in the first burner unit, a large amount of air-fuel mixture in which fuel is lean and uniform can be supplied to the flame hole.

In the above construction, a fuel-lean mixture is ejected from the flame hole of the first burner unit and burns, and a fuel-rich mixture is ejected from the flame hole of the second burner unit. And burn.

Combustion of excess air by a fuel-lean mixture alone has poor flame stability. However, a stable flame of the above-described fuel-rich mixture exists adjacent to these flames. These stable flames act as pilot flames to stabilize the excess air flame. Therefore, no flame lift or oscillating combustion occurs, and the generation of noise is suppressed.

Since the combustion of the fuel-lean mixture stabilized by the flame of the fuel-rich mixture is combustion of excess air, the temperature of the flame is kept low by the cooling action of the excess air. NOx generation is reduced. Also, the amount of fuel gas provided for combustion as a fuel-lean mixture is
Since it is larger than the amount of fuel gas provided as a fuel-rich mixture, the amount of NOx generated relative to the combustion amount of the entire burner is also small.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings.
1 and 4 are perspective views showing one example of the first and second burner units 1a and 1b, respectively, in the present invention. Each of the first and second burner units 1a and 1b is provided on the upper part of a vertical flat burner body 2a and 2b, respectively.
3b, fuel gas and air inlets 4a, 4b on the lower side
And mixing pipe portions 5a and 5b extending from the introduction portions 4a and 4b to the flame holes 3a and 3b. The first burner unit 1a has a configuration in which the vertical width of the burner body 2a is wider than the vertical width of the burner body 2b of the second burner unit 1b, and the distance from the introduction part 4a to the flame hole part 3a. Is longer than that of the second burner unit 1b.

The first and second burner units 1a, 1
b of the burner body 2a, 2b is a thin upper portion u
And a thick lower portion d, the upper portions u have flame holes 3a and 3b at the upper end, and the lower portion d has an introduction portion 4
a, 4b and the mixing pipe sections 5a, 5b. The flame holes 3a and 3b are formed by narrowing the long slit-like openings 6a and 6b at the upper end of the upper portion u at predetermined intervals to form a plurality of short slit-like openings arranged in a line. In addition, the flame hole portions 3a and 3b can employ an appropriate configuration such as a configuration in which a number of transverse slits are arranged.

The introduction portions 4a and 4b are formed as openings which are open at one end of the lower portion d, and throat portions 7a and 7b are formed inside the openings. Then, from the throat portions 7a, 7b, facing the other end of the lower portion d,
Mixing pipe parts 5a, 5b that are turned back to the lower end of upper part u
Is composed. The introduction section 4a and the mixing pipe section 5b of the first burner unit 1a have a larger diameter than those of the second burner 1b, so that a larger amount of fuel gas and air can be introduced.

On the other hand, the first and second burner units 1a, 1a,
1b, both of the upper portion u, the narrowed portion 8
a, 8b, and the first burner unit 1
A narrowing portion 9 is formed at a predetermined interval at a predetermined interval on the upstream side of the throttle portion 8a to form a rectifying portion. Although not shown in FIG. 4, a sleeve fire forming plate 10 is provided outside the upper part u of the second burner unit 1b as shown in FIG. Correspondingly upper part d
Is provided with a mixed air outlet (not shown) for forming a sleeve flame.
Note that these components can be appropriately configured.

FIGS. 5 to 8 show the structure of a burner constituted by the above-described first and second burner units 1a and 1b. FIG. 5 shows the whole structure in which a part of the same structure is omitted. FIG. 6 is a plan view, FIG. 6 is an overall front view showing the air chamber 11 and a part of the first and second nozzle holders 12a and 12b, and FIG. 7 is an enlarged view of a main part of FIG. FIG. 8 is an enlarged front view of a main part showing a state, and FIG. 8 is a side view.

As shown in these figures, in the burner of the present invention, a large number of the first and second burner units 1a and 1b are connected to the flame holes 3a and 3b at the same height or a slight height difference. The support boxes 13 are arranged alternately with
It is supported and configured. In the embodiment, as shown in FIGS. 6 and 7, the height of the flame hole 3a of the first burner unit 1a is slightly lower than the height of the flame hole 3b of the second burner unit 1b. It is installed at a height substantially equal to the upper end of the fire forming plate 10. As is clear from FIGS. 5 and 6, the second burner units 1b are located at both ends of the burner.

As described above, the first burner unit 1a
Is constructed so that the vertical width of the burner body 2a is wider than the vertical width of the burner body 2b of the second burner unit 1b, so that the first burner as shown in FIG. 6, FIG. 7 and FIG. The introduction part 4a of the unit 1a is connected to the second burner unit 1b.
Are arranged in a horizontal line at a position lower than the introduction portion 4b. Since the introduction portions 4b of the second burner unit 1b are arranged in a horizontal line between the upper portions u of the burner bodies 2a of the first burner unit 1a, the first burner unit 1a is provided.
Despite having a large-diameter introduction section 4a and a mixing pipe section 5a, the distance between the adjacent upper members u of the first and second burner units 1a and 1b can be reduced and installed. Therefore, these first and second burner units 1
a and 1b can be mounted in a row with high density.

The support box 13 has two upper and lower nozzle holders 12a, 1b corresponding to the upper and lower rows of the introduction portions 4a, 4b of the first and second burner units 1a, 1b.
2b, ie, the lower first nozzle holder 12a corresponding to the first burner unit 1a and the second burner unit 1
The configuration is such that the upper second nozzle holder 12b corresponding to b is installed. These nozzle holders 12a,
Reference numeral 12b is installed in an air chamber 11 having an open front side, and air is supplied from a fan 14 into the air chamber 11.

The first and second nozzle holders 12a and 12b are provided with fuel gas jetting nozzles 15a and 15b corresponding to the respective inlets 4a and 4b. The diameters and positions of these nozzles 15a and 15b and the opening diameters of the introduction portions 4a and 4b are set so as to satisfy the following conditions. That is, these components corresponding to the first burner unit 1a supply a fuel-lean mixture to the flame hole portion 3a in which the amount of fuel gas is greater than that supplied to the second burner unit 1b. The above-mentioned components corresponding to the second burner unit 1b are set so as to satisfy the condition for supplying a fuel-rich mixture to the flame hole 3b. For example, the flame hole 3 of the first and second burner units 1a and 1b
The air ratio of the air-fuel mixture supplied to a and 3b is the theoretical air amount λ = 1.
Then, it can be set so that λ ≒ 1.2 to 1.5 and λ ≒ 0.4, respectively. Also, each of the flame holes 3a,
The ratio of the amount of fuel gas supplied to 3b is, for example, first burner unit 1a: second burner unit 1b = 8: 2
It can be set to be about 6: 4. However, these air ratios and fuel gas amount ratios can be appropriately determined beyond these ranges.

Next, FIG. 9 shows a state relating to the nozzle holder as viewed from the back side with respect to the nozzle.
FIG. 10 shows a state viewed from the side, in which the first and second nozzle holders 12a and 12b are
a, 16b are divided into three parts l, r, m at the left, right, and middle.
r, 17 m, and a fuel gas supply pipe 1
8l, 18r, 18m are provided. As can be seen from the arrangement of the nozzles 15a and 15b in these figures, the second burner unit 1b is provided at both ends of the burner of the present invention having a large number of burner units 1a and 1b arranged in a row as described above. Is located. And the second nozzle holder 1
The second burner unit 1b corresponding to the nozzles 15b at both ends of the intermediate portion m of the second nozzle 2b is provided with the first nozzle holder 12
a corresponding to the nozzles 15a at both ends of the intermediate portion m of
Of the burner unit 1a.

In the burner of the present invention having the above-described structure, first, fuel gas is supplied to all the fuel gas supply pipes 18l, 18r, 18m, and the first and second fuel gas supply pipes 18l, 17r, 17m are connected to each other. Fuel gas is supplied to the nozzle holders 12a and 12b, and air is supplied from the fan 14 into the air chamber 11 to perform combustion.

First and second nozzle holders 12a, 12
b is supplied to the respective nozzles 15a, 15a
b corresponding to the introduction part 4 of the burner units 1a, 1b
The gas is ejected in the directions a and 4b, and is introduced into the burner bodies 2a and 2b while sucking ambient air by the energy of the ejected energy. In this way, the burner body 2a,
The fuel gas and air introduced into 2b move through mixing pipe sections 5a and 5b while mixing, and reach respective flame holes 3a and 3b, from which they are ejected as an air-fuel mixture for combustion. At this time, as described above, the fuel-lean mixture is ejected from the flame hole 3a of the first burner unit 1a,
The fuel-rich mixture is ejected from the flame hole 3b of the burner unit 1b, and the amount of fuel gas in the mixture which is ejected from the flame hole 3a of the first burner unit 1a is reduced by the second burner unit 1b. Is larger than the amount of fuel gas in the air-fuel mixture ejected from the flame hole 3b.

By the supply of the air-fuel mixture as described above, a flame (first flame 19a) formed by burning the fuel-lean air-fuel mixture is formed above the flame hole 3a of the first burner unit 1a. Above the flame hole 3b of the second burner unit 1b, there is a flame (second flame 1) due to the combustion of the fuel-rich mixture.
9b) is formed. At this time, the second burner unit 1
b is located at both ends of the burner, so that the first flame 1
The second flame 19b always exists on both sides of 9a.

Since the first flame 19a is due to combustion of a fuel-lean mixture, the stability is poor alone, but the second flames 19b located on both sides of the first flame 19a are due to combustion of a fuel-rich mixture. Therefore, the second flame 19b, which is stable, acts as a pilot flame to stabilize the first flame 19a. Therefore, the first flame 19a
Lift and vibration combustion hardly occur, and the generation of noise is suppressed.

The stability of the first flame 19a due to fuel-lean combustion also depends on the mixing state of the air-fuel mixture, and if the mixing is not sufficiently uniform, the stability is poor. In this regard, in the burner according to the present invention, as described above, the flame hole 3 is formed from the introduction portion 4a of the first burner unit 1a.
The distance to a is longer than that of the second burner unit 1b. Therefore, the mixing distance is long, so that the fuel gas and the air are well mixed, and even if the fuel is lean, a large amount of the air-fuel mixture uniformly mixed can be supplied to the flame hole 3a. Therefore, in the burner of the present invention, the stability of the first flame 19a is also good in this respect.

Since the combustion of the fuel-lean mixture stabilized as described above is the combustion of excess air, the temperature of the flame 19a is maintained at a low temperature by the cooling action, and the generation of NOx is reduced. . Further, since the amount of fuel gas supplied to the fuel as a fuel-lean mixture is larger than the amount of fuel gas supplied to the fuel-rich mixture as described above, the amount of NOx relative to the combustion amount of the entire burner is increased. The amount generated is also small.

Next, in the above combustion state, the supply of fuel gas from the fuel gas supply pipe 18r on the right side in the drawing is stopped, and the right and left portions r of the first and second nozzle holders 12a and 12b are stopped. When the supply of all the fuel gas is stopped, the first and second burner units 1a and 1b corresponding to the nozzles 15a and 15b in this portion are extinguished, and the nozzle holder 1 is turned off.
Nozzle 15 in middle part m and left part l of 2a, 12b
First and second burner units 1 corresponding to a and 15b
Combustion of only the groups a and 1b continues.

The burning burner units 1a, 1
Since the second burner unit 1b is located on both ends of the group b, the second flame 19b always exists on both sides of the first flame 19a as in the above-described combustion state. The stabilizing action of the first flame 19a by the second flame 19b is not hindered.

Next, in the above combustion state, when the supply of the fuel gas from the intermediate fuel gas supply pipe 18m is further stopped, the first and second nozzle holders 12a and 12b corresponding to the intermediate portion m of the nozzle holder 12b are stopped. 1, second burner unit 1a, 1
Only group b continues burning. In this combustion state,
Since the second flame 19b always exists on both sides of the first flame 19a, the stabilizing action of the first flame 19a by the above-described second flame 19b is not hindered.

As described above, in the above embodiment, the area of the burned hole to be burned can be changed stepwise without impeding the stabilization of the first flame 19a by the second flame 19b. By using a well-known control method of the combustion amount such as proportional control, it is possible to appropriately adjust the combustion amount over a wide range.

FIG. 11 shows NOx in the burner of the present invention.
It shows an example of emission characteristics. In this example, in the burner shown in the figure, the air ratio of the fuel-rich mixture in the second burner unit 1b is set to λ = 0.4 to 0.7 and the air ratio of the entire burner is set. Represents the generation amount of NOx when the air ratio of the fuel-lean mixture in the first burner unit 1a is adjusted to the value shown on the horizontal axis in the figure and burned. The indicated air ratio is a value including the cooling air when the cooling air flows around the burner units 1a and 1b.
The air ratio in parentheses is a value not including the cooling air. The ratio between the amount of fuel gas burned in the first burner unit 1a and the amount of fuel gas burned in the first burner unit 1b is 7.5: 2.5.
As shown in the figure, in the burner of the present invention, it can be seen that the amount of generated NOx is significantly reduced as compared with the conventional general Bunsen burner.

FIG. 12 shows an example of the limit of the lift of the first flame 19a by the first burner unit 1a in the burner according to the present invention, in comparison with the others. First, A is a burner according to the present invention, in which the fuel-lean mixture is supplied only to the first burner unit 1a and the second burner unit 1b does not perform flame holding by the second flame. The lift limit of the first burner unit 1a is shown, and this limit is about λ = 0.7. On the other hand, B
Indicates a lift limit in a conventional general Bunsen burner having a flame holding mechanism, and this limit is about λ = 1.3. C indicates the lift limit of the first burner unit 1a when the first and second burner units 1a and 1b are burned in the burner of the present invention, and λ = 3.0. It is about. Thus, it can be seen that the burner of the present invention can stably burn the excess excess air and can reduce NOx by the combustion of the excess excess air as compared with the conventional general Bunsen burner. .

[0034]

As described above, the present invention has the following effects. The first burner unit for burning a fuel-lean mixture and the second burner unit for burning a fuel-rich mixture can be densely mounted alternately, and a small-sized burner with a large combustion amount can be obtained. . Since the ratio of the amount of fuel gas used for combustion of excess air is large, the amount of NOx generated is small relative to the combustion amount of the entire burner. The combustion of the excess air can be performed stably without causing the lift of the flame or the oscillating combustion, so that the generation of noise is suppressed. Since the fuel-lean mixture is obtained by mixing fuel gas and air for each burner unit, even if flashback occurs due to clogging or the like and mixing is not performed smoothly, it is limited to a local area and generates loud noise. And damage is prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a first burner unit constituting a burner of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view taken along line YY of FIG. 1;

FIG. 4 is a perspective view showing one embodiment of a second burner unit constituting the burner of the present invention.

FIG. 5 is a plan view in which a configuration of a burner of the present invention is partially omitted.

FIG. 6 is a front view showing a burner according to the present invention with a part cut away.

FIG. 7 is an enlarged front view of a main part of FIG.

FIG. 8 is a side view showing the configuration of the burner of the present invention.

FIG. 9 is a front view of the nozzle holder constituting the burner of the present invention as viewed from the back side of the nozzle.

FIG. 10 is a side view of the nozzle holder shown in FIG.

FIG. 11 is an explanatory diagram showing the amount of NOx generated by the burner of the present invention in comparison with a conventional Bunsen burner.

FIG. 12 is an explanatory view showing an example of a flame lift limit of the first burner unit in the burner according to the present invention, in comparison with the others.

[Explanation of symbols]

 1a 1st burner unit 1b 2nd burner unit 2a, 2b Burner body 3a, 3b Flame hole 4a, 4b Introducing portion 5a, 5b Mixing tube portion 6a, 6b Long slit opening 7a, 7b Throat portion 8a, 8b Restricted portion 9 Narrowed portion 10 Sleeve fire forming plate 11 Air chamber 12a, 12b Nozzle holder 13 Support box 14 Fan 15a, 15b Nozzle 16a, 16b Partition plate 17l, 17r, 17m Communication pipe 18l, 18r, 18m Fuel gas supply pipe 19a first flame 19b second flame l left part r right part m middle part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigetoshi Akiyama 201 Nishi-Kashiwara Nitta, Fuji City, Shizuoka Prefecture Takagi Sangyo Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) F23D 14/08 ZAB F23C 11/00 329 F23C 11/00 ZAB

Claims (2)

(57) [Claims] 1. A flame hole portion on an upper part of a vertical flat burner body,
A plurality of first and second burner units, which constitute a fuel gas and air introduction section on the lower side and constitute a mixing pipe section extending from the introduction section to the flame hole section, are arranged alternately in a row. The first burner unit positions the introduction portion below the introduction portion of the second burner unit and has a large diameter so that a larger amount of fuel gas and air can be introduced. A fuel gas ejection portion is arranged corresponding to each of the introduction portions of the first and second burner units, and the first burner unit is provided with a fuel-lean and an amount of fuel gas to the second burner unit. A low-nitrogen oxide generating burner, wherein a mixture richer than the supply amount is supplied and a fuel-rich mixture is supplied to the second burner unit. 2. The burner according to claim 1, wherein the burner body comprises an upper portion having a small thickness and a lower portion having a large thickness. A low-nitrogen oxide burner comprising an inlet portion and a mixing pipe portion, wherein a lower portion of the second burner unit is arranged between an upper portion of the first burner unit.