JP3226181B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized combustion device for household use or small business use, which uses a low-concentration burner with low nitrogen oxide generation.

[0002]

2. Description of the Related Art Nitrogen oxides (NOx) in the combustion gas of a burner in various types of combustion equipment cause environmental destruction. Therefore, a burner used in a combustion apparatus reduces the amount of NOx generated. Various measures have been developed and implemented for this purpose. Examples of the countermeasures include application of a lean burn method or a lean burn method that suppresses thermal NOx by lowering the flame temperature by burning excess air.

However, these countermeasures have been taken for large-scale combustion equipment for industrial use and commercial boilers for which there are legal restrictions, and for small-sized combustion equipment for home use and small commercial use. Therefore, it cannot be said that sufficient measures have been taken due to problems such as noise cost.

[0004] In the case of large-sized combustion equipment, the conditions for countermeasures against noise are not severe, and the combustion chamber can be large.
Since the capacity of the combustion fan can be increased, NOx reduction measures can be taken effectively by forming a lean flame or split flame, or applying various combustion methods such as turbulent combustion or slow combustion. It could be burned.

[0005] For example, when the concentration combustion method is applied, as the air-fuel mixture becomes leaner, the combustion speed decreases due to excessive air combustion and the ejection speed increases, so that the flame length tends to increase. However, since the above-described turbulent combustion can be applied to large-sized combustion equipment, the length of the flame can be shortened by the vortex generated in the turbulent flame, and the flame can be increased because the combustion chamber can be large. Could prevent incomplete combustion due to reaching the heat exchanger and generation of CO.

[0006]

However, it is more difficult to reduce NOx in small-sized combustion equipment, especially small-sized high-load combustion equipment than in large-sized combustion equipment. When applied to small-sized combustion equipment, the combustion noise must be minimized in small-sized combustion equipment, so the turbulent combustion cannot be applied, and laminar flame combustion must be realized as much as possible. In the combustion of, the combustion speed is reduced due to excessive air combustion, and the injection speed of the air-fuel mixture is increased, so that the flame length is increased. FIG. 10 shows the combustion rate of natural gas (1 atm, room temperature) with respect to the air ratio, and it can be seen that the combustion rate decreases as excess air is used.

[0007] As the mixture becomes leaner,
In addition to the combustion speed being reduced due to excessive air combustion, the injection speed of the air-fuel mixture is increased, so the flame length becomes longer. And the inconvenience of incomplete combustion and generation of CO occurs. As a method of shortening the flame length, there is a method of decreasing the ejection speed by increasing the area of the flame port. In this method, when the input is reduced, the back is caused to cause a turn-down ratio (TD).
R) becomes small, and high load combustion cannot be obtained due to a decrease in area heat load.

[0008] Therefore, the present invention provides a method for controlling NOx
It is an object of the present invention to provide a combustion apparatus that achieves reduction of the load, high load combustion, and CO suppression.

[0009]

The combustion apparatus according to the present invention comprises a rich burner for supplying a fuel-rich mixture and a lean burner for supplying a fuel-lean mixture, which are alternately arranged side by side, In the light and heavy burners in which the amount of gas supplied to the light burner is larger than the amount of gas supplied to the rich burner, the total sum of the lengths of the adjacent lines of the light burner and the dense burner is set under a constant area heat load. Thus, the generation of CO is reduced.

That is, the combustion apparatus according to the first aspect of the present invention is provided with a heat exchanger above the burner, and uses a rich burner (rich burner unit 1a) for burning a fuel-rich mixture and a fuel-lean mixture. a hotel combustion device pale burner for burning (pale burner units 1b), arranged alternately with said light burner and the dark burner are adjacent to each other, the dark burner and the pale burner was reduced in capacity To reduce the area of each burner hole , and the surface of the dense burner and the light burner .
High heat load of 1,000,000 kcal / m ² h or more
Sum of lengths of adjacent lines between the dense burner and the light burner
Is set to 50 mm or more per 1000 kcal / h of combustion heat
It is characterized by becoming.

[0011] Combustion of excess air by a lean fuel mixture in a lean burner alone has poor flame stability, but is stabilized by a rich fuel mixture in a rich burner adjacent to these flames. Because of the presence of the flame, these stable flames act as pilot flames, stabilizing the flame of the excess air, and transferring excess heat from the flame of the rich fuel gas mixture to the flame of the excess air. The flame temperature of air rises to increase the combustion speed, which contributes to shortening of the flame. When the flame is shortened, it becomes difficult for the tip of the flame to reach the heat exchanger even in a small combustion chamber, and therefore, the generation of CO due to the cooling of the flame is reduced.

If the sum of the lengths of the adjacent lines of the rich burner and the light burner is increased under the condition that the outer shape of the flame outlet is the same and the area heat load is constant, the flames of the rich burner and the light burner are subdivided. Since each flame is brought into contact, the flame can be shortened sufficiently, and a sufficient CO reduction effect can be obtained.

In such flame shortening, since the injection speed of the fuel-lean mixture is not reduced and the load on the flame outlet is not reduced, when the input is reduced, the back occurs and the turndown ratio decreases. There is no.

The area heat load of the rich burner and the light burner is set to high load combustion of 1,000,000 kcal / m ² h or more.
, The kite to set the sum of the lengths of the dark burner and light burner adjacent lines or units combustion <br/> sintered heat 1000 kcal / h per 50mm
With this, it is possible to realize high-load combustion as well as lean combustion.
Ox and CO can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings.

FIG. 1 and FIG. 2 show an embodiment of the combustion apparatus of the present invention. The dark burner unit 1a as a dark burner and the light burner unit 1b as a light burner constitute a burner by alternately arranging slit-shaped flame ports a and b adjacent to each other. In this embodiment, dark burner units 1a are arranged at both ends, and four dark burner units 1a and 3
Two light burner units 1b are arranged in a row to constitute a burner. The outer shape of the burner unit surface 2 as a whole of this burner is rectangular as shown in FIG. 1, and the area heat load of the burner unit surface 2 is 1,000,000 kcal / m ² h.
It is set to the above high value.

The burner units 1a and 1b are configured to supply and burn a fuel-rich mixture or a fuel-lean mixture through appropriate fuel mixing means (not shown). Appropriate configurations used for burners and other premix burners can be applied.

Assuming that the air ratio of the air-fuel mixture supplied to each of the rich burner unit 1a and the light burner unit 1b is the theoretical air amount λ = 1, for example, λ ≒ 1.6 to 2.2,
It is set so that λ ≒ 0.5 to 0.8. Further, the total amount ratio of the fuel gas amount supplied to each burner unit 1a, 1b is, for example, light burner unit 1b: rich burner unit 1a = about 8: 2 to 6: 4, and the gas amount supplied to light burner unit 1b. Is set to be larger than the total amount of gas supplied to the rich burner unit 1a. The air ratio and the fuel gas amount ratio can be arbitrarily determined beyond the above ranges.

By the supply of the air-fuel mixture as described above, a flame 3a due to the combustion of the fuel-rich air-fuel mixture is formed on the flame port a of the rich burner unit 1a, and the flame 3a is formed on the flame port b of the light burner unit 1b. A flame 3b is formed by the combustion of the fuel-lean mixture, and these flames come into contact with each other and burn. At this time, since the rich burner unit 1a is set at both ends of the burner, the flame 3b is sandwiched between the flames 3a.

The flame 3b, which is a combustion of a fuel-lean mixture, has poor stability alone, but the flame 3a, which is a combustion of a fuel-rich mixture on both sides thereof, is stable. For this reason,
The flame 3a acts as a pilot flame on the flame 3b and stabilizes the flame 3b. Therefore, lift and vibration combustion are unlikely to occur in the flame 3b, which is a combustion of a fuel-lean mixture, and generation of noise is suppressed.

As described above, since the combustion of the stabilized fuel-lean mixture is the combustion of excess air, the temperature of the flame 3a 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 combustion as a fuel-lean mixture is larger than the amount of fuel gas supplied to the fuel-rich mixture, NOx relative to the combustion amount of the entire burner is increased. The amount of generation is also small.

FIG. 7 shows an example of NOx emission characteristics in the combustion apparatus of the present invention. This example
Burners as shown in the figure (note that each burner unit 1a,
Various configurations such as the shapes of the flame ports a and b in 1b are appropriately selected. )), The air ratio of the fuel-rich mixture in the rich burner unit 1a is set to λ = 0.4 to 0.7, and the air ratio of the burner as a whole is set to the value shown on the horizontal axis in FIG. NOx when combustion is performed by adjusting the air ratio of the fuel-lean mixture in the lean burner unit 1b
It is the amount of generation. The displayed air ratio is
When the cooling air flows around the burner units 1a and 1b, the value includes the cooling air, and the air ratio in parentheses is a value that does not include the cooling air. The ratio between the amount of fuel gas burned in the light burner unit 1b and the amount of fuel gas burned in the rich burner unit 1a is 7.5: 2.5. As shown in the figure, it can be seen that the combustion apparatus according to the present invention, that is, the burner has a significantly reduced NOx generation amount as compared with a conventional general Bunsen burner.

FIG. 8 shows a comparative example of the lift limit of the flame 3b of the light burner unit 1b in the combustion apparatus of the present invention. A, in the burner according to the present invention, supplies a fuel-lean mixture only to the lean burner unit 1b,
This shows the lift limit of the flame 3b of the light burner unit 1b when the flame holding by the flame 3a of the rich burner unit 1a is not performed, 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.
It is about 1.3. C is a light burner unit 1b in the case where the burners 1a and 1b are simultaneously burned in the burner according to the present invention.
, And λ = approximately 3.0.

As described above, in the combustion apparatus according to the present invention, compared with the conventional general Bunsen burner, the combustion of high excess air can be performed more stably, and the reduction of NOx by the combustion of high excess air can be achieved. it can.

Next, the flame 3a of the rich burner unit 1a has a combustion stabilizing effect on the flame 3b of the light burner unit 1b, and heat is transferred from the flame 3a of the fuel-rich mixed gas to the flame 3b of excess air. Causes the temperature of the flame 3b to rise. The increase in the temperature of the flame 3b increases the burning speed of the fuel-lean mixture, and shortens the flame 3b.
When the flame 3b is shortened, it becomes difficult for its tip to reach the heat exchanger or the like. As a result, the distance between the flame 3b and the heat exchanger or the like can be shortened by that much, and the combustion chamber is reduced in size and the flame cooling is caused. CO generation will also be reduced.

Such an operation is achieved by the light burner unit 1b.
3b and the flame 3 of the dense burner unit 1a on both sides
Due to the interaction of a, under the condition that the area heat load is constant,
It is correlated with the sum A of the lengths of the adjacent lines per unit heat of combustion of the light burner unit 1b and the dense burner unit 1a. Here, taking the case of the burner shown in FIG.
Set of burner units 1a and 3 sets of burner units 1b
Are arranged alternately, so that each burner unit 1
a, 1b length of each length L and to lever, such as the length of the sum 6L adjacent lines Runode, per unit amount of combustion heat adjacent line
Sum A is 6L × C of. Where C is the unit heat of combustion
/ The total amount of heat of combustion. Therefore, when the sum of the lengths A of the adjacent lines is increased under the condition that the outer shape of the burner unit surface 2 is the same and the area heat load is constant, the light burner unit 1
b and the flames 3b, 3a of the rich burner unit 1a are subdivided, and the flames 3b, 3a are brought into contact with each other.
Along with shortening of the flame 3b, a sufficient CO reduction effect can be obtained.

FIG. 9 shows an example of CO emission characteristics in the embodiment of the combustion apparatus of the present invention. That is, this is a burner (note that each burner unit 1a, 1
The configuration such as the shape of the flame outlets a and b in b is appropriately selected. ), The area heat load on the burner unit surface 2 is reduced to 1
100,000 kcal / m ² h, heat of combustion is 1000 kcal / h,
The relationship between the total sum A of the lengths of the adjacent lines per 1000 kcal / h of unit combustion heat and the emitted CO is determined by an experiment. As can be seen from the figure, the amount of CO emission is A
Falls within the range of 30 to 50 mm, rapidly decreases as A increases, and saturates to a low value above 50 mm. Therefore, under such burner conditions, A can be set to an appropriate value of 50 mm or more per unit of 1000 kcal / h of combustion heat to suppress the generation of CO.

By the way, if the value of A is set to A> 50 mm or more, the light burner unit 1b and the dark burner unit 1a
However, the number of components can be increased to achieve high-density mounting, but the cost may increase due to material costs and assembly. Also,
Even if A> 50 mm or more, a significant reduction in CO emission cannot be expected. Therefore, the total length A may be set to an appropriate value in consideration of reduction of CO and cost.

Next, another embodiment of the combustion apparatus according to the present invention will be described. In FIGS. 3 and 4, the dense burner unit 1a has a front-end ejection section 4 provided with a slit-shaped flame port a on the upper side. It is formed thinly to form a space between the side wall 5 and the front-end ejection portion 4 to form a sleeve flame port 6. On the other hand, the light burner unit 1b has a ribbon 7 provided at the tip to form a large number of flame openings.

FIG. 5 shows another embodiment of the combustion apparatus according to the present invention. In this embodiment, instead of the slit-shaped flame port a of the dense burner unit 1a in the configuration of FIGS. The ribbon 8 is provided at the tip end similarly to the flame port b of the light burner unit 1b to form a large number of flame ports a, the sleeve flame port 6, and the sleeve flame forming side wall 5 spaced apart outside. Is formed.

FIG. 6 shows another embodiment of the combustion apparatus according to the present invention. In this embodiment, the rich burner unit 1a,
A large number of flame ports a and b constituting the light burner unit 1b are formed by the ceramic plate 9,
a, the light burner unit 1b, and the burner as a whole are integrally formed. That is, a large number of flame ports a and b are linearly arranged on the ceramic plate 9 to form a flame port group, and the flame port groups are alternately arranged to form a dense burner unit 1a. And the light burner units 1b are alternately arranged in rows. Although the diameter of the burner port b constituting the light burner unit 1b is smaller than the diameter of the burner port a constituting the dense burner unit 1a, the number thereof is large, and the burner ports b are arranged in two rows in the figure. Thus, a large amount of fuel-lean mixture can be supplied to the flame outlet b.

In addition to the above-described embodiments, the present invention is configured such that a rich burner unit for supplying a fuel-rich mixture and a light burner unit for supplying a fuel-lean mixture are arranged adjacently and alternately. Any type of light and light burner may be used as long as the gas amount supplied to the light burner unit is larger than the gas amount supplied to the light burner unit.

[0033]

As described above, according to the present invention,
Equipped with a heat exchanger above the burner to burn a rich mixture
A burner that burns a rich burner and a fuel-lean mixture
The height of the combustion chamber of the combustion device with a burner can be reduced,
The back can be prevented even if the input is reduced,
A large noise reduction ratio reduces NOx, high load combustion and
A combustion device that achieves CO suppression can be provided.

[Brief description of the drawings]

FIG. 1 is a partial sectional perspective view showing one embodiment of a combustion apparatus of the present invention.

FIG. 2 is a front view of the combustion device of FIG. 1;

FIG. 3 is a partial sectional perspective view showing another embodiment of the combustion apparatus of the present invention.

FIG. 4 is a sectional view showing another embodiment of the combustion apparatus of the present invention.

FIG. 5 is a sectional view showing another embodiment of the combustion apparatus of the present invention.

FIG. 6 is a partially cutaway perspective view showing another embodiment of the combustion apparatus of the present invention.

FIG. 7 is a diagram showing a comparison of NOx generation amounts between the combustion device of the present invention and a conventional Bunsen burner.

FIG. 8 is a view showing a comparative example of a flame lift limit of a light burner unit in the combustion apparatus of the present invention.

FIG. 9 is a diagram showing CO emission characteristics in the combustion device of the present invention.

FIG. 10 is a diagram showing a correlation between an air ratio and a combustion speed.

[Explanation of symbols]

 1a Dark burner unit (dark burner) 1b Light burner unit (light burner) 3a, 3b Flame

──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Takao Takagi 201 Nishi-Kashiwara Nitta, Fuji City, Shizuoka Prefecture Inside Takagi Sangyo Co., Ltd. (72) Inventor Kimio Mochizuki 201 Nishi-Kashiwara Nitta, Fuji City, Shizuoka Prefecture Takagi Sangyo Stock In-company (72) Inventor Shigetoshi Akiyama 201 Nishi-Kashiwara Nitta, Fuji City, Shizuoka Prefecture Inside Takagi Sangyo Co., Ltd. (56) References JP-A-4-151408 (JP, A) JP-A-1-219406 (JP, A ) JP-A 4-73713 (JP, U) JP-A 4-63914 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 14/02 F23D 14/08 F23D 14 / 14 F23C 11/00 330

Claims (1)

(57) [Claims] 1. A combustion device comprising a heat exchanger above a burner and comprising a rich burner for burning a fuel-rich mixture and a light burner for burning a fuel-lean mixture, wherein the rich burner and the burner pale and burner arranged alternately to be adjacent to each other, the addition to reduce the respective burner port area by concentrated burner and the small capacity of the pale burner, the dark burner and the pale burner area thermal load 1 million over kcal / m ² h
With high load combustion, the sum of the lengths of adjacent lines between the rich burner and the light burner is calculated as 5 per 1000 kcal / h of combustion heat.
A combustion device characterized by being set to 0 mm or more .