JPH04371709A - Combustion device - Google Patents

Abstract

PURPOSE:To provide a combustion device which responds to low NOX combustion and each kind of gas properly, reduce combustion noise and increase the variable range of combustion quantities. CONSTITUTION:A burner main body 2 having a first burner port 1 is provided with a second premixing air chamber 5 having a second burner port 4 and an air intake part 8 communicated with the chamber 5 an one side of a first mixing air chamber 3. There are provided a first passage 12 which supplies mixed air to the first burner port 1 inside the first mixing air chamber 3 and a projection section 13 having an introduction port of mixed air provided on a plane parallel the flow of mixed air in the first mixing air chamber 1. A direction change section 21, which guides the air from the air intake part 8 is provided to a second passage 16 formed on the burner main body so as to communicate the first mixing air chamber 3 with the second mixing air chamber 5. The introduction port 15 is provided on the up stream side of the second passage 16. The direction change section 21 allows the mixed air from the second passage 16 to be mixed with the air from the air intake part 8, thereby discharging a lot of mixed air from the second passage 16. This construction makes it possible to burn a large portion of fuels by weak flames at low flame temperature generated at the second burner port 4 and embody thick and thin fuel combustion of low NOX.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention mainly focuses on low NO in burners.
The present invention relates to a combustion device that is designed to achieve high efficiency and low noise.

0002

2. Description of the Related Art Conventionally, this type of household burner has a structure as shown in FIGS. 3 and 4. That is, a first gas mixture chamber 3 provided in the burner body 2 having a first flame port 1 and a second gas port 4 configured on both sides of the first gas mixture chamber 3.
a second air mixture chamber 5 having A flame stabilizing plate 7 is formed between the second flame opening 4 and stabilizes the flame base, and the burner body 2
An air intake part 8 is provided at the lower part of the space between the two to set the primary air ratio of the second mixture chamber 5, and an air intake part 8 is provided inside the first mixture chamber 3 to equalize the mixture distribution in the longitudinal direction of the burner body 2. A pressure equalizing plate 9 is provided for this purpose. A large number of burner bodies 2 having such a configuration were housed inside the burner case 10.

[0003] In the combustion apparatus having the above structure, a stable rich flame with a low oxygen concentration is formed above the first flame port 1. In addition, a large amount of air from the air intake port 8 and the mixture supplied from the mixture passage 6 become a lean mixture outside the flammable limit inside the second mixture chamber 5, and flow out from the second flame port 4. The flame was combusted under the thermal influence of the rich flame in the first flame opening 1, forming a lean flame with a high oxygen concentration. Then, the lean flame, which has low NOx concentration and unstable characteristics, is stabilized with a rich flame, achieving concentrated combustion as a whole, and N
They were trying to reduce the generation of Ox.

0004

However, in the above-mentioned conventional configuration, the air-fuel mixture from the air-fuel mixture passage 6 does not mix sufficiently with the air from the air intake section 8, and is transferred to the second flame port 4 as a rich air-fuel mixture. In addition to preventing the formation of a lean flame on the second flame port 4, the air-fuel mixture in the first air-fuel mixture chamber 3 is made uniform in the longitudinal direction of the burner body 2 by the pressure-equalizing plate 9. The air-fuel mixture that has passed has a flow vector in the vertical direction, making it difficult for the air-fuel mixture to be released from the air-fuel mixture passage 6 to the second air-fuel mixture chamber 5, and as a result, it burns above the second flame port 4. There has been a problem in that it is difficult to significantly reduce NOx because the ratio of the lean flame to the total combustion amount decreases and the ratio of the rich flame formed above the first flame port 1 increases.

[0005] The present invention solves the above problems, and
The purpose is to increase the oxygen content.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a burner body having a first flame port and a first mixture chamber communicating therewith, and a first mixture chamber of the burner body. A second air mixture chamber provided on the side of the air chamber and having a second flame port, an air intake portion provided in the second air mixture chamber, and a protrusion inside the first air mixture chamber. A first passage for supplying the mixture to the first flame opening, and an air-fuel mixture introduction provided on the plane of the parallel part of the first passage parallel to the flow of the mixture in the first mixture chamber. a second passage provided in the burner body so as to communicate between the mouth, the first mixture chamber, and the second mixture chamber, and a direction change for guiding air from the air intake section to the second passage outlet; The first passage has a configuration in which the inlet is provided upstream of the second passage.

[0007]

[Operation] With the above structure, the present invention guides the air from the air intake part to the second passage outlet by the direction changing part, so that the air-fuel mixture ejected from the second passage is forcibly mixed with the air. The mixture becomes a lean mixture and is ejected from the second flame port. Also, the mixture flowing through the first mixture chamber first passes between the protrusion and the first mixture chamber, flows to the second passage, diffuses with the air from the air intake, and reaches the second flame opening. The remaining mixture is introduced into an inlet that supplies the air-fuel mixture to a first flame port provided parallel to the flow direction and is discharged from the first flame port. Therefore, most of the air-fuel mixture flows into the second passage, and some of the air-fuel mixture flows into the first passage. In other words, a sufficiently mixed lean air-fuel mixture can be supplied, and the combustion amount of the lean flame can be easily set to be larger than the combustion amount of the rich flame.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. Note that the same components as in FIGS. 3 and 4 are given the same reference numerals. In FIGS. 1 and 2, a first flame port 1 having a large number of slits is provided on the upper surface of a burner body 2. As shown in FIGS. A protrusion 11 is formed in the first mixture chamber 3 of the burner body 2 in parallel to the flow direction of the mixture, and the protrusion 1
A first passage 12 is provided within 1 . The protruding part 11 consists of a tip part 13 and a parallel part 14 parallel to the flow direction of the air-fuel mixture.
Inlet ports 15 are provided along the longitudinal direction of the burner body 2 at optimal intervals to regulate the amount of air-fuel mixture to the first flame port 1. Second passages 16 are provided on both sides of the burner body 2 at optimal intervals in the longitudinal direction of the burner body 2. The second passage 16 is provided in a horizontal portion formed by expanding both side surfaces of the burner body 2 from the middle. The end of the injection plate 18 is inserted into the groove formed by the support 17 and the burner body 2, and the adjacent burner bodies 2 are connected and integrated. The injection plate 18 is formed into a mountain shape by bending a flat plate, and the inclined part 19 has a second flame opening part 4 consisting of a large number of small openings.
By forming horizontal parts 20 at both ends, flame stabilizing parts are formed on both sides of the upper part of the burner main body 2. A space between the burner bodies 2 and surrounded by the injection plate 18 and located downstream of the second passage 16 becomes a second air-fuel mixture chamber 5 . Reference numeral 8 denotes an air intake portion of the second air mixture chamber 5, and downstream of the air intake portion 8, a V-shaped direction changing portion 21 is provided between each burner body 2. A throat section 2 is provided on the upstream side of the burner body 2.
A plurality of such burner bodies are arranged side by side to constitute a burner block, which is housed inside the burner case 10. A fuel pipe 24 in which a nozzle 23 for injecting fuel is provided facing each throat portion 22 and a fan 25 are provided in the burner case 10.

In the above structure, part of the combustion air supplied from the fan 25 flows into the burner body 2 from the throat portion 22, and most of the remaining air flows between the burner bodies 2, that is, the air intake. After flowing through the inlet portion 8 and having its direction of inflow changed to above the outlet of the second air-fuel mixture passage 16 by the direction changing portion 21, it is supplied to each of the second air-fuel mixture chambers 5. On the other hand, the fuel supplied from the fuel pipe 24 is ejected from each nozzle 23 toward each throat portion 22, flows into the burner body 2, mixes with air, and is supplied to the first mixture chamber 3. . Here, the air-fuel mixture in the first air-fuel mixture chamber 3 flows upward, and most of it rises through the space between the burner body 2 and the protruding part 11 and flows through the second passage 16 into the second air-fuel mixture. The remaining gas is discharged into the air chamber 5 via the inlet 15 perpendicular to the upward flow, passes through the first passage 12, and is discharged from the first flame port 1. Therefore, the air-fuel mixture ejected from the second air-fuel mixture passage 16 perpendicularly intersects with the air whose incoming direction has been changed above the exit of the second air-fuel mixture passage 16 by the direction changing unit 21, and collides violently with the air. Mixing is promoted and a uniform lean mixture is supplied to the second mixture chamber 5. Furthermore, by providing the inlet 15 parallel to the flow direction and upstream of the second passage 16, and by providing the second passage 16 perpendicular to the flow direction, the directionality of the upward flow of the air-fuel mixture is controlled. This makes it possible to release more air-fuel mixture than the second passage 16.

Next, the original combustion principle of this burner will be explained. The primary air ratio of the air-fuel mixture inside the first air-fuel mixture chamber 3 is set to 30 to 60%. A part of this air-fuel mixture is ejected from the first flame port 1 to form a rich flame, and most of the remaining air-fuel mixture flows through the second passage 16 to the second air-fuel mixture chamber 5.
and mixes with a large amount of air entering from between the burner body 2. At this time, the primary air ratio was changed from 170 to 25.
After the mixture becomes a lean mixture of about 0% and outside the flammable range and is homogenized, it is ejected obliquely from the second flame port 4 provided in the inclined section 19. The lean mixture is ignited by the thermal influence of the rich flame formed above the first flame port 1, resulting in lean combustion. Thermal NOx
The lower the temperature of the combustion reaction zone, the lower the amount of NOx generated. Therefore, the leaner the mixture containing a larger amount of air, the higher the heat capacity, the lower the flame temperature, and the lower the NOx. Therefore, by reducing the amount of combustion of the rich flame and increasing the amount of combustion of the lean flame, the amount of NOx generated by this burner can be reduced. In our settings, the ratio of the uniform lean flame combustion amount to the total combustion amount is 0.8 to 0.7, and the NOx value is 40 ppm.
I can do it to a certain degree. However, with the conventional burner configuration, the ratio could only be increased to about 0.6, and the lean mixture could only be mixed to an incomplete state. With this configuration, the ratio could be increased to about 0.8 and a uniform lean mixture could be supplied. As a result, the amount of NOx generated could be significantly reduced.

[0011] Here, to explain the case where the lean mixture is not sufficiently mixed, the mixture discharged from the second passage 16 does not mix with the air flowing between the burner bodies 2 and forms a laminar flow. A rich flame is formed at the second flame port 4, and a thin mixture or air is discharged from the second flame port 4. A thin flame/air layer with insufficient dilution is formed at the flame port 4 and is used as secondary air for the surrounding rich flame. Therefore,
NOx decreases as the original lean flame decreases and the rich flame increases.
The amount generated cannot be reduced.

Furthermore, simply by changing the passage area of the inlet 15, the ratio between the combustion amount of the rich flame and the combustion amount of the lean flame can be changed. Therefore, it is possible to set the optimum ratio between the combustion amount of rich flame and the combustion amount of lean flame for various gas types.

Furthermore, when the amount of combustion becomes small, the jet flow velocity of the air-fuel mixture from the first flame port 1 and the second flame port 4 decreases, and the flame approaches the respective flame ports. Furthermore, if the supplied air amount fluctuates, the combustion amount will be small, so the air-fuel mixture inside the second air-fuel mixture chamber 5 may fall into the flammable range. At this time, the lean flame tries to advance inside the second mixture chamber 5, but since the second flame port 4 is set to have a hole diameter smaller than the extinguishing diameter, the inside of the second mixture chamber 5 prevent flame from backfiring. Therefore, stable combustion can be obtained even if the amount of combustion is reduced.

Further, the injection plate 18 is a plate material that is integrally molded and bent, and is inserted into the gap formed between the support 17 and the burner body 2, so that the vertical wall of the injection plate 18 and the wall of the burner body 2 are mutually connected. Since they are closely joined, the rigidity of the burner block as a whole increases and no deformation occurs. Therefore, it is possible to reduce variations in the mixture ratio of the second air mixture chamber 5 due to the occurrence of gaps that cannot be managed in terms of design, and to stabilize performance.

[0015]

As explained above, according to the combustion apparatus of the present invention, the following effects can be obtained. 1) Since the mixing of the air-fuel mixture and air can be promoted compared to the conventional method, the lean air-fuel mixture can be made uniform, and a homogenized lean flame can be formed on the second flame port, thereby achieving low NOx. 2) Compared to the conventional method, the combustion amount of a lean flame can be larger than that of a rich flame, so most of the fuel is combusted by the lean flame with a low flame temperature formed on the second flame opening. This makes it possible to achieve low NOx. 3) Since the area of the inlet for supplying the air-fuel mixture to the first flame port can be easily changed, it is possible to set the optimal ratio of the lean flame combustion amount to the rich flame combustion amount for various gas types.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a combustion device in an embodiment of the present invention.

[Figure 2] A perspective view of the main parts of the device

[Figure 3] Partial cross-sectional view of a conventional combustion device

[Figure 4] Side view of the conventional device

[Explanation of symbols]

1 First flame opening part 2　Burner body 3 First mixture chamber 4 Second flame opening part 5 Second air mixture chamber 8 Air intake part 11 Protruding part 12 First passage 15　Introduction port 16 Second passage 21 Direction change part

Claims (1)

[Claims] Claim 1: A burner body having a first flame opening and a first mixture chamber communicating therewith; a second flame opening provided on the side of the first mixture chamber of the burner body; a second air mixture chamber having an air intake portion provided in the second air mixture chamber; and an air intake portion provided in the first air mixture chamber, and an air intake portion provided in the first air mixture chamber; a first passage for supplying air; a mixture inlet provided on a plane of a parallel portion of the first passage parallel to the flow of the mixture in the first mixture chamber; a second passage provided in the burner body so as to communicate the air chamber and the second mixture chamber; and a direction change part that guides air from the air intake part to the second passage outlet. A combustion device in which the introduction port is provided upstream of the second passage.