JPH09105505A - Combustion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of nitrogen oxide by supplying mixed gas having high ratio of fuel amount to an air amount to a first burner, and supplying mixed gas having low ratio of fuel amount to the air amount with much air amount and fuel amount to a second burner. SOLUTION: The combustion apparatus uses as a first burner (or second burner) a flame retention type premixing burner 1, which has a main flame port 2 and a flame retention burner port 3. Burner ports 4 are linearly arranged, the port 2 is formed in a circular hole at the top of a burner body, and the ports 3 are arranged and formed in smaller circular hole than the port 2 at the oblique part formed from the top to the side face side. Fuel concentrated mixed gas having higher ratio of fuel amount to the air amount is supplied to the first burner. Lean fuel mixed gas having low ratio of fuel amount to the air with more air amount and fuel amount is supplied to the second burner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device used for a small-sized combustion device for home use or business use, and relates to a burner which suppresses generation of nitrogen oxides and the like.

[0002]

2. Description of the Related Art Combustion gas generated by combustion of burners used in various combustion apparatuses includes nitrogen oxides (N
O _X ). The NO _X is itself toxic to the human body, when released to the outside air is expected to be one of the causes generating the acid rain and photochemical smog. Therefore,
To reduce the generation amount of the NO _X, various countermeasures have been taken in the burner.

[0003]

The conventional countermeasure is for a large combustion device for industrial use or the like, which is legally regulated, and the burner for a combustion device for home use or small business use is a countermeasure. However, due to problems such as noise generation, it cannot be said that sufficient measures have been taken. In a large combustion device, the static pressure of the combustion fan can be increased, so that the flow of mixed gas or air as fuel can be easily controlled, the layout for the burner is high, and noise measures are easy. Moreover, no strict controlling condition against noise, etc., the combustion chamber can be made large, there is an advantage that it is easy to complete combustion be subjected to reduction measures of the NO _X by the so-called slow combustion. On the other hand, in a small-sized combustion device, the static pressure of the combustion fan is smaller than in a large-sized combustion device, it is difficult to control the flow of mixed gas and air, the layout is less flexible with respect to the burner, and noise countermeasures are difficult. , and the strict controlling condition against noise, etc., the combustion chamber low, NO _X reduction measures are difficult.

Accordingly, an object of the present invention is to provide a combustion apparatus in which the generation of nitrogen oxides is suppressed by the combined combustion of a fuel-rich mixed gas and a fuel-lean mixed gas.

[0005]

As shown in FIGS. 1 to 3, a combustion apparatus according to the present invention is a combustion apparatus using a flame retention type premix burner, and includes first and second burner bodies. (Flame plate 7 or premix burner 1)
To the second burner body is supplied with a fuel rich mixture gas having a high ratio of fuel amount to air amount, and the second burner body is provided with an air amount larger than the air amount and a fuel amount larger than the fuel amount. By supplying a fuel-lean mixed gas having a low ratio of fuel amount to air amount, combustion of the mixed gas by the first burner body and combustion of the mixed gas by the second burner body are performed. It is characterized by being generated independently.

In the combustion apparatus of the present invention, the first burner body (the premixing burner 1 or the flame hole plate 7) is supplied with a fuel-rich mixture, that is, a mixed gas, and the second burner body (flame) is used. The perforated plate 7 or the premix burner 1) has a fuel lean ratio in which the ratio of the fuel amount to the air amount is low, with an air amount greater than the air amount on the first burner body side and a fuel amount greater than the fuel amount. Combustion is performed by supplying a mixed gas. Since the fuel rich mixture gas is burned by the first burner body (premix burner 1) in the combustion region with a low oxygen partial pressure, N
Generation of O _X is suppressed.

Further, the fuel-lean mixed gas is jetted out and combusted above the second burner body (flame plate 7). Since this combustion is combustion of excess air, the cooling action of this excess air is performed. Keeps the temperature of the flame (8) low and NO _x
Is suppressed. Although the combustion of the excess air alone has poor flame stability, the flame (4) of the first burner body (premix burner 1) acts as a pilot flame, and even if the combustion of the excess air occurs, the flame of the flame is not affected. Stability, that is, combustion stability is improved. Therefore, the lift of the flame (8) and the oscillating combustion do not occur, and the generation of noise is suppressed. Further, since the excess air acts to supply secondary air to the combustion of the first burner body, incomplete combustion in the combustion of the fuel-rich mixed gas can be prevented.

Further, the combustion apparatus of the present invention is characterized in that the first burner body is installed within the space between the pair of second burner bodies as illustrated in FIGS. . This is because the fuel rich mixture gas having a high fuel amount ratio to the air amount is supplied between the second burner bodies to which the fuel lean gas mixture having a low fuel amount ratio to the air amount is supplied. This is the case where the first burner body is installed. Such an arrangement, the combustion of the first and second burner body results in complement each other, the generation of the NO _X is suppressed, without causing the lift and oscillating combustion of the flame (8), Generation of noise can be suppressed, and incomplete combustion in the combustion of the fuel-rich mixed gas can be prevented.

The first burner body (premix burner 1)
In the operation of supplying the fuel-lean mixed gas to the combustion and burning it, the temperature of the flame corresponding to both ends of the combustion device as a whole is low, so the combustion chamber is designed to be narrow and the water cooling wall of the heat exchanger burns. When it is close to both ends of the device, it is possible to prevent overheating.

Further, the combustion apparatus of the present invention is characterized in that the second burner body is installed within the interval between the pair of the first burner bodies as illustrated in FIGS. 1 to 3. . That is, between the first burner body (the premix burner 1 or the burner plate 7) to which the fuel-rich mixed gas having a high fuel ratio with respect to the air amount is supplied, the fuel having a low fuel ratio with respect to the air amount A second burner body (flame plate 7 or premix burner 1) to which a dilute mixed gas is supplied is provided. In this case, the fuel rich mixture gas has a low oxygen partial pressure in the combustion region due to the first burner bodies (premix burner 1) located on both sides of the second burner body (flame plate 7). Because it burns at
The generation of NO _X will be suppressed. Then, the fuel-lean mixed gas burns with the second burner body, and since this combustion is combustion of excess air, the temperature of the flame (8) is kept low by the cooling action of the excess air, and NO _X
Is suppressed. In the combustion of the excess air, since the combustion of the first burner body (premix burner 1) acts as a pilot flame, the flame stability is improved. It is as described above that the flame (8) is not lifted or vibrated, thereby suppressing the generation of noise. Then, the excess air supplies the secondary air to the flame (4) of the first burner body, so that the incomplete combustion in the combustion of the fuel-rich mixed gas can be prevented.

Further, as shown in FIGS. 1 to 3, the combustion apparatus of the present invention is characterized in that the first and second burners independently form a flame above them. If the flames are independently formed above, it is possible to prevent generation of a local high-temperature portion in a portion where the flames overlap and unstable combustion due to formation of a turbulent flow region.

Further, the combustion apparatus of the present invention is characterized in that, as exemplified in FIGS. 1 to 3, the second burner body has a flame hole plate in which a number of slits are formed as flame holes. I do. This makes it possible to inject a fuel-rich gas mixture efficiently.

Further, the combustion apparatus of the present invention is characterized in that, as exemplified in FIGS. 1 to 3, the first or second burner body is constituted by a metal porous plate or a ceramic porous plate. The first or second burner body may be made of a metal plate having a large number of slits formed as flame holes, or may be made of a ceramic porous plate having a large number of appropriately shaped flame holes formed therein.

[0014]

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

FIG. 1 shows a first embodiment of the combustion apparatus of the present invention. For example, a flame retention type premixing burner 1 is used as a first burner body (or a second burner body) in the combustion apparatus. The premixing burner 1 includes a main flame hole 2 and a sleeve flame hole 3. And Flame 4
Are arranged on a straight line, the main flame hole 2 is a circular hole and is formed at the top of the burner main body, and the sleeve flame hole 3 is a circular hole smaller than the main flame hole 2 and extends from the top to the side surface side. It is arranged and formed on the formed inclined portion. Such an arrangement form,
By way of example, the premix burner 1 can have an appropriate configuration as long as it is a frame retention type.

In this combustion apparatus, a pair of premixing burners 1 are arranged at a fixed interval, and an interval section 5 is provided as means for maintaining the interval. Between the premix burners 1, for example, a burner plate 7 is provided as a second burner body (or a first burner body). , Protruding from the top of the premix burner 1. Therefore, the configuration is such that the mixed gas of the fuel gas and the air is supplied through the flame hole plate 7 and the interval portion 5. In this embodiment, the flame hole plate 7 is formed of a metal plate in which a number of long hole slits are formed as the flame holes 6, but the shapes of the flame hole plate 7 and the flame holes 6 are arbitrary, and the material is metal. Alternatively, ceramics or the like may be used. Flame hole 6
If it is configured to be separated from the premixing burner 1, the flames 4 and 8 are independently formed above the premixing burner 1 and the flame hole plate 7, so that it is possible to prevent the occurrence of overlapping portions of each flame. .

The method for supplying the mixed gas to the flame plate 7 and the method for mixing the fuel and air are the same as the methods for supplying and mixing the mixed gas to the premix burner 1. Can be. An air flow passage 10 is provided between the partition plate 9 and the premix burner 1.

The configuration of the combustion device shown in FIG. 1 can be configured as a single unit, or by arranging a plurality of units as a unit to form a combustion device having a desired combustion amount. be able to.

Next, FIG. 2 shows a second embodiment of the combustion apparatus of the present invention. In this combustion device, three premix burners 1 are arranged at intervals, and a flame hole plate 7 is provided at the interval 5 to supply a mixed gas of fuel gas and air. . According to such a configuration, the number of the perforated plates 7 formed by the premix burner 1 and each interval portion 5 is changed, so that a burner having a desired combustion amount proportional to the fuel amount of the premix burner 1 can be obtained. it can. Also in this configuration, a partition plate 9 is provided at an interval outside the premix burner 1, and an air flow passage 10 is formed between the partition plate 9 and the premix burner 1. However, the air flow passage 10 may be provided as needed.

In the above configuration, as described above, the fuel-rich mixed gas is supplied to the premix burner 1 and
The fuel-lean mixed gas is supplied to the burner plate 7 to perform combustion, and the fuel-rich mixed gas above the premix burner 1 is mixed with the excess air of the flame 8 above the burner plate 7 together with the air flow passage 10.
Since the air supplied from the fuel is burned as secondary air, it is possible to prevent the occurrence of incomplete combustion in the combustion of the fuel-rich mixed gas. In addition, when the fuel-lean mixture gas is supplied to the premix burner 1 and the fuel-rich mixture gas is supplied to the flame hole plate 7 to perform combustion, supply of secondary air from the air flow passage 10 is performed. There is no need for Therefore, in the case of configuring a combustion device that performs combustion by supplying such a mixed gas, the air flow passage 10 does not need to be provided.

Further, a fuel-rich mixed gas is supplied to either one of the premix burner 1 and the flame hole plate 7, and
When the fuel-lean mixed gas is supplied to the other side to perform the lean combustion, the air ratio of the mixed gas supplied to each of them is, assuming that the theoretical air amount is λ = 1, for example, in the case of the fuel-rich mixed gas, λ is about 0.4, λ is about 1.2 ~
A mixed gas mixed to be 1.5 is supplied.

Therefore, the fuel-rich mixed gas is supplied to one of the premixed burner 1 and the burner plate 7 to perform combustion, and the fuel-lean mixed gas is supplied to the other side to perform the lean-burn combustion. the by causing, it is possible to realize a combustion of the low NO _X with low noise, it is possible to compensate for the reduction in efficiency due to the combustion of the excess air.

Next, FIG. 3 shows an example of an implementation result of the combustion apparatus of the present invention. This experimental result shows that the fuel-rich mixed gas, premixed burner 1 was burned using the burner shown in FIG.
The graph shows a change in the NO _X emission amount with respect to the excess air ratio of the supplied mixed gas as a whole when the fuel-lean mixed gas is supplied to the burner plate 7 and burned. In this case, the supply amount of fuel in the mixed gas to the premix burner 1 and
The ratio of the supply amount of the fuel gas in the mixed gas to the flame plate 7 is
It is about 1: 2.

In the experimental results shown in FIG. 3, A represents the characteristics of the burner in the combustion apparatus shown in FIG. 1, and B represents the conventional burner. Compared with the conventional burner, such as Bunsen burner which is often used at a small combustion device, the combustion device of the present invention, it can be seen the generation amount of the NO _X is very small.

[0025]

As described above, according to the present invention,
Since the combustion of the fuel-rich mixed gas and the combustion of the fuel-lean mixed gas having a large amount of fuel and air and a high air-to-fuel ratio are caused, the fuel-rich combustion is it is possible to supply the excess air due to lean combustion, the fuel rich combustion can act as a priming fuel lean combustion, the reduction of the generation amount of the NO _X by the combustion of the fuel rich mixture gas, It can coexist and reduction of the generation amount of the NO _X from the combustion of lean fuel gas mixture, to improve the flame stability of combustion of the fuel lean gas mixture can suppress noise, incomplete fuel rich mixture gas prevents combustion, without an increase in noise can be prevented even if the reduction in efficiency with reduced NO _X.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a first embodiment of a combustion device of the present invention.

FIG. 2 is a partial perspective view illustrating a second embodiment of the combustion apparatus of the present invention.

FIG. 3 is a graph showing NO _X emission characteristics as an experimental result of the combustion device shown in FIG. 1;

[Explanation of symbols]

1 Premixed burner (first burner body or second burner body) 4 Flame 6 Flame hole 7 Flame hole plate (second burner body or first burner body) 8 Flame

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuya Sugawara 2-11-2 Kajigaya, Takatsu-ku, Kawasaki City, Kanagawa Prefecture (72) Takao Takagi 201 Nishi-Kashiwara Nitta, Fuji City, Shizuoka Prefecture Inside Takagi Industry Co., Ltd. (72) Inventor Kimio Mochizuki 201 Nishi-Kashiwara Nitta, Fuji City, Shizuoka Prefecture Inside Takagi Industries Co., Ltd. (72) Inventor Shigetoshi Akiyama 201 Nishi-Kashiwara Nitta, Fuji City, Shizuoka Prefecture Inside Takagi Industries Co., Ltd.

Claims (7)

[Claims] 1. A combustion device using a flame retention type premix burner, comprising first and second burner bodies, wherein the first burner body has a high ratio of fuel amount to air amount. A rich mixture gas is supplied, in which a rich mixture gas is supplied, and the second burner body has an air amount larger than the air amount and a fuel amount larger than the fuel amount, and the ratio of the fuel amount to the air amount is low. Is supplied to cause the combustion of the mixed gas by the first burner body and the combustion of the mixed gas by the second burner body to occur independently. 2. The combustion apparatus according to claim 1, wherein the first burner body is installed within an interval between the pair of second burner bodies. 3. The combustion device according to claim 1, wherein the second burner body is installed within a space between the pair of first burner bodies. 4. The combustion apparatus according to claim 1, wherein the first and second burners independently form a flame above the first and second burners. 5. The combustion apparatus according to claim 1, wherein the second burner body includes a flame hole plate in which a number of slits are formed as flame holes. 6. The combustion apparatus according to claim 1, wherein the first or second burner body is formed of a metal perforated plate. 7. The method according to claim 1, wherein the first or second burner body is formed of a porous ceramic plate.
Or the combustion device according to 3.