JPS5977206A - Burner device - Google Patents

Abstract

PURPOSE:To suppress production of NOX in combustion gas, by a method wherein a nozzle, through which the direction of fuel injected extends at a given angle with an axis, is employed, and adjoining nozzles are disposed so that their fuel injection nozzles are turned toward the opposite direction at each other. CONSTITUTION:First and second nozzles 12 and 13 are constituted such that the directions, shown by arrow marks 22 and 23, of the fuel injected through injection nozzles 24, extend at an angle 4 with the direction of an axis. The nozzles are disposed so that the injection nozzles 24 of plural adjoining nozzles (12 or 13) are turned toward the opposite direction to each other to form fuel surplus ranges 25 and 26. A first and a second combustion range are separately and independently formed, and this enables suppression of production of NOX.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a combustion device used in boilers and the like, and particularly to a combustion device suitable for reducing nitrogen oxides (hereinafter referred to as NOx) in exhaust gas. It is.

[Prior art]

In recent years, there has been a demand for the development of a combustion method that suppresses the generation of NOx, which is a substance that causes photochemical oxidants. NOx generated in a combustion furnace can be roughly divided into two types: thermal NOx, which is generated at high temperatures and high oxygen concentrations, and two-element NOx, which is generated from nitrogen contained in fuel.

Conventionally known combustion methods for suppressing the generation of NOx mainly include: (1) supplying air with an air ratio (supplied air amount/theoretical air amount) of 1 or less, that is, less than the theoretical air amount; This is the so-called two-stage combustion method, in which a primary combustion zone is formed by the combustion process, and a secondary combustion zone is formed by introducing the insufficient amount of air into its wake. There is a method of recirculating exhaust gas that is supplied to the burner section of the equipment.

In both cases (1) and (2) above, the combustion reaction in the burner section is slowed down and the combustion temperature is lowered, thereby particularly suppressing the generation of thermal NOx.

In addition to the combustion methods mentioned above, a new combustion method has been proposed to further suppress the generation of NOx, which takes advantage of the fact that the flame formed at a low air ratio has the effect of reducing NOx. . That is, a first burner with a certain air ratio;
If the air ratio is lower than 1, the second burner is combined, and the first
The NOx generated in the first burner is reduced to harmless nitrogen (N2) by the low air ratio flame of the second burner. Note that in this case, in order to compensate for the air shortage in the first burner and the second burner, air is introduced around these burners or in their wake.

Below, a conventional combustion device using this combustion method is shown in Figure 1.
This will be explained based on FIG. FIG. 1 is a sectional view of a conventional combustion device, and FIG. 2 is a schematic front view of the combustion device shown in FIG.

In these figures, 11 is an impeller placed in the center of the burner part of the combustion device, 12 is the impeller, and 1 is a first nozzle that injects fuel placed around the impeller. 13 is a first nozzle 120. 14 is a swirl generator for supplying all or part of the combustion air to the vicinity of the first nozzle 12; 15 is a combustion furnace (chamber); 15' is a The wall of the combustion furnace 15, 16 is a port (air injection hole) provided in the combustion furnace 15, and 10.20 is a fuel distribution pipe. The fuel ejected from the first nozzle 13 creates an excess fuel flame, which causes the first nozzle 12 to
NOx produced by the combustion of fuel ejected from
This is to reduce the Furthermore, in order to reduce this NOx, the amount of air passing through the swirl generator 14 is reduced to lower the air ratio, and a portion of the amount of air required for combustion is transferred from the port 16 downstream of the nozzle 12.13. may be supplied. In this manner, the conventional combustion apparatus, whether or not a portion of the combustion air is supplied from the port 16,
Combustion furnace 15 using the NOx reduction effect caused by excess fuel flame
The aim is to reduce NOx emitted from the engine. In such a conventional combustion device, the primary combustion zone 30 is generated by combustion of the fuel injected from the first nozzle 12.
In addition, independently generating the secondary combustion zone 40 generated by combustion of the fuel ejected from the second nozzle 13 has a large effect on the suppression of NOx. That is, the first
The NOx reduction effect can be increased by supplying the fuel ejected from the nozzle 13 to the downstream side of the next combustion zone 30 and mixing it with the exhaust gas on the downstream side. However, in the conventional combustion device for suppressing the generation of NOx shown in FIG.
Ideally, it would not be possible to generate them independently.

[Purpose of the invention]

The present invention has been made in view of the actual state of the prior art as described above, and its purpose is to further suppress the generation of NOx in exhaust gas than before by improving the above-mentioned combustion device. To provide combustion equipment.

[Summary of the invention]

To achieve this objective, the combustion device of the present invention comprises a first
, a second small nozzle (the fuel ejection direction of one of the nozzles has a predetermined angle with respect to the axis of the nozzle, and for at least one of the first and second nozzles, adjacent nozzles The nozzles are arranged so that their fuel injection holes face in alternate directions, and when these nozzles emit fuel in different directions, the pairs of nozzles arranged in different directions form excess fuel regions. It has become.

Furthermore, in the case where the ejection holes of both the first and second nozzles are arranged facing in alternate directions, the excess fuel area formed by the j-th nozzle and the excess fuel area formed by the second nozzle Each pair of these nozzles is staggered so that the fuel-rich areas do not coincide with each other.

[Embodiments of the invention]

Hereinafter, the combustion device of the present invention will be explained in detail based on the drawings. FIG. 3 is a schematic front view showing the configuration of a combustion device according to an embodiment of the present invention, FIG. 4 is a sectional view showing a nozzle of the combustion device of FIG. 3, and FIG. 5 is a fuel injection in the combustion device of the present invention. 3 is a graph showing the relationship between the direction angle θ and the NOx concentration ratio.

The combustion device according to an embodiment of the present invention shown in FIG. 3 has the same basic structure as the device shown in FIGS. 1 and 2 except for the nozzle structure, and is designated by the same reference numerals. Items indicate identical parts. That is, as shown in FIG. 4, the first nozzle 12 and the second nozzle 13 of the combustion apparatus of the present invention are configured such that the fuel jetting direction indicated by arrows 22 and 23 of the fuel jetting from the jetting hole 24 is the first nozzle 12 and the second nozzle 13. 1 nozzle 12, 2nd nozzle]
It has an angle ψ with respect to the axial direction of 3. Also, the jetting pattern of the fuel jetted from the nozzles 12 and 13 is the third
It is made by arranging the nozzles 12, 13 as shown in the figure. That is, in both the first nozzle 12 and the second nozzle 13, the nozzles are arranged so that the ejection holes 24 of the plurality of adjacent nozzles (12 or 13) face in opposite directions, During the fuel eruption of these nozzles, the nozzles whose ejection holes 24 are substantially opposite each other form a fuel excess region 5.26°C. Excess fuel region 5 and second nozzle 13
Each pair of these nozzles 12.13 is arranged staggered so that the fuel excess region 26 formed by each pair of nozzles 12.1; By arranging them in this way, the primary combustion zone (see 30 in FIG. 1) and the secondary combustion zone (also see 40) can be generated separately and independently.

Next, the effects of the present invention will be explained by showing the results of combustion experiments. Using a nozzle as shown in FIGS. 3 and 4, the NOx concentration at the outlet of the combustion furnace was measured while changing the angle θ (shown in FIG. 3) of the fuel injection direction by 22.5°. In addition,
The combustion conditions are as follows.

Fuel: Propane Fuel amount: 1st nozzle 12 is 5 Nm”/h 2nd
2.5 Nm3/h total fuel amount from nozzle 13 of
7.5 Nm3/11 Angle ψ of fuel injection direction (Fig. 4): Nozzle 12 is 30' Nozzle 13 is 50° Air ratio: Combustion furnace outlet is constant at 1.1 Primary combustion zone is 15 and 0.8 (the missing part is port 16
) Under these combustion conditions, the angles θ and N of the fuel injection direction
The relationship with the Ox concentration ratio was measured. The results are shown in the graph of FIG. The horizontal axis of this graph shows the angle θ1 of the fuel injection direction. The vertical axis shows the NO concentration ratio. The NOx concentration ratio is the N at θ-00 in the case of a conventional device.
The NOx value at each angle with respect to the Ox value, ie, the value obtained by dividing the NOx value at each angle by the NOx value when θ=0°. In this graph shown in Figure 5, A is the first
When the air ratio in the next combustion zone is 15, B is 0.8, and both A and E have a minimum value of NOx when θ is around ±4b0, and this value is compared to the conventional device. It can be seen that the NOx value has decreased by about 39%. Note that θ is 180
The reason why the NOx value is higher than that of the conventional device near
2.23) both face the central axis of the burner, so the primary combustion zone and the secondary combustion zone are not formed separately. In addition, the NOx reduction effect is different when the air ratio in the primary combustion zone is 15 and 08. Already 40
% was also low, which is probably because the NOx emission value was close to the limit value.

In the above embodiment, both the first nozzle 12 and the second nozzle 1:3 have angles ψ and θ, but the nozzle 1
2 or by adding angles ψ and υθ to one side of the nozzle 130, the NOx reduction effect can be achieved. In addition, in the above embodiment, as shown in FIG. 3, there are four first nozzles 12 and four second nozzles 13 each, and they are arranged at 90° intervals (angle α in FIG. 3). The number of nozzles and the angle α are not limited to these, and the nozzles may be arranged eccentrically. In either case, the NOx reduction effect of the present invention can be obtained satisfactorily. Furthermore, although gaseous fuel was used as the fuel in the above experimental example, the present invention is not limited thereto, and the effects of the present invention can be obtained satisfactorily even in the case of co-combustion of gaseous fuel and liquid fuel.

〔Effect of the invention〕

As described above, in the combustion device of the present invention, two types of nozzle groups that eject fuel are arranged so that the areas with high fuel concentration and the areas with low fuel concentration do not coincide, so the first combustion area and the second N
This has the effect of satisfactorily suppressing the generation of Ox.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional combustion device, FIG. 2 is a schematic front view of the combustion device shown in FIG. 1, FIG. 3 is a schematic front view of a combustion device according to an embodiment of the present invention, and FIG. 4 is a sectional view of the nozzle of the combustion device of FIG. 3, and FIG. 5 is a graph showing the relationship between the angle θ of the fuel injection direction and the NoXa degree ratio in the combustion device of the present invention. 10.20 Fuel distribution pipe 1 impeller 12...1st
Nozzle 13, second nozzle 14... swirl generator
J5...Combustion furnace 15'/Wall 16/Port (air injection hole) 22.23 Arrow 25 indicating fuel injection direction/Excess fuel area 26 due to first nozzle...Second
Excess fuel area 30 due to the nozzle of 1st combustion area
40・Second Combustion Zone 50...Third Combustion Zone Patent Attorney Junnosuke Nakamura Figure 1 Figure 2 Figure 3 Figure 5 Figure 4 'Funsudo λ ~ Iriri

Claims (4)

[Claims] (1) A plurality of first nozzles are arranged near the center of the burner section to which fuel is ejected, a plurality of first nozzles to which air is supplied are arranged near the center of the burner section, and a second nozzle having an ejection hole which ejects fuel is arranged around the first nozzle.
In the combustion device in which a plurality of nozzles are arranged, the first,
The fuel ejection direction of at least one of the second nozzles has a predetermined angle with respect to the axis of the nozzle, and the fuel ejection direction between adjacent nozzles of at least one of the first and second nozzles A combustion device in which the nozzles are arranged such that the holes face in alternating directions, and when fuel is injected from the nozzles, a fuel-excess region is formed between the pairs of the staggered nozzles. (2) the fuel ejection directions of both the first and second nozzles are at predetermined angles with respect to the axis of the nozzle;
Regarding both the first and second nozzles, the ejection holes of adjacent nozzles are oriented in alternate directions (
The nozzles are arranged such that when the nozzles eject fuel, the pair of nozzles form an excess fuel area, and the excess fuel area formed by the first pair of nozzles and the second excess fuel area are formed by the pair of nozzles. 2. The combustion apparatus of claim 1, wherein each pair of nozzles is staggered so that the fuel excess regions formed by the nozzle pairs do not coincide. (3) The combustion device according to claim 1, wherein air is supplied near the second nozzle. (4) The combustion device according to claim 1, further comprising an air ejection hole through which air is ejected downstream of the first and second nozzles.