JPH0233506A - Nox and dust reducing burner - Google Patents

Abstract

PURPOSE:To reduce the concentration of soot without increasing the density of NOx contained in the exhaust gas by installing a fuel spray atomizer where a plurality of ejection holes are divided into two groups or more, and the adjoining ejection holes are laid out in positions having different distances from the axial center of said atomizer. CONSTITUTION:An atomizer comprises a chip main body 1, a back plate 4, and a cap nut 11 of said atomizer. Fuel 2 is distributed mixing ejection holes 10alpha, 10beta and 10gamma respectively virtually on an equal basis via a fuel supply hole 9alpha through a fuel communication pipe 5 where a plurality of opening are board on the back plate 4 of the atomizer. The fuel 4 and an enhanced fine particle medium 3 are collided and mixed with each other in the respective ejection holes 10alpha, 10beta and 10gamma, turned into more enhanced fine particles, atomized, and ejected from the atomizer. The flow of fuel thus atomized is mixed with the combustion air, thereby forming flames. Six ejection holes 10alpha, 10beta and 10gamma are distributed on a circumference whose radial diameters are different from each other, centering on the axial center of the atomizer. The fuel density in the atomized fuel flow can be shaded while the exhausted NOx density can be reduced by dividing burner flames into two sections.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a combustion device, and in particular has a fuel spray atomizer suitable for reducing soot and nitrogen oxides (NOx) in combustion exhaust gas. The present invention relates to a burner for burning fluid fuel.

[Conventional technology]

In recent years, reflecting the diversification of imported crude oil, the crude oil used in industrial boilers, which represent a large energy consumption sector, has become heavier. As a result, there has been a demand for more sophisticated heavy oil combustion technology. This is not unrelated to the suppression of energy-related capital investment due to changes in economic trends and the stagnation of the momentum to switch to coal-fired boilers, and the trend toward cheaper heavy oil is predicted to continue for a long time. . On the other hand, the use of inexpensive heavy oil, which is said to be less flammable, is being planned and put into practical use in large-scale oil-fired couplants for industrial use. However, in the combustion of heavy oil, because the fuel contains a large amount of residual carbon and nitrogen, soot and dust (cenospheres) are produced in the combustion exhaust gas.
The generation of large amounts of nitrogen oxides (NOx) and the increase in the concentration of nitrogen oxides (NOx) have become major problems. In particular, when the crystal structure of the residual carbon is in a highly flame-retardant form, a so-called flow structure, the problem of soot and dust generation becomes even more serious. Furthermore, in industrial boilers with a small number of burners, a problem arises in that soot is generated significantly.

In order to solve these problems, (1) an atomizer with excellent atomization properties is used in the burner to burn the heavy oil with the average spray droplet diameter as small as possible; (2) Improve the mixing of the sprayed fuel and combustion air. Countermeasures have been considered. For example, as shown in FIGS. 9 and 10, the 10 groups of mixing injection holes for the fuel atomization medium 3 and the fuel 2 are divided into two or more groups, and the groups are arranged in the same circle with respect to the axis of the tip body 1 of the atomizer. N having an atomizer in which mixing jet holes 10 are arranged partially off-centered on the periphery.
An Ox reduction burner has been proposed (Japanese Patent Laid-Open No. 50-566
Publication No. 35).

[Problem to be solved by the invention]

As mentioned above, in the conventional heavy oil burner atomizer, there are two orifices for mixing a plurality of atomization media and fuel.
Divide into three or more groups, add density to the fuel spray flow,
NO in the flue gas is reduced by distributed delayed mixing of combustion air.
x has been reduced, but no consideration has been given to the generation of soot and dust. In other words, since the mixing nozzles within a group are adjacent to each other, combustion air cannot enter and diffuse between each fuel spray stream, resulting in delayed combustion and failure to achieve rapid ignition of the fuel. For.

This was a factor in increasing the soot and dust concentration in exhaust gas. In particular, in the case of inferior flame-retardant fuel oil, there is a problem in that the soot and dust concentration tends to increase even more markedly.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide liquid fuel such as heavy oil or 00M or An object of the present invention is to provide a combustion burner for fluidized fuel such as CWM.

[Means to solve the problem]

An object of the present invention is to have a fluid fuel supply channel that supplies liquid fuel or a fluidized fuel that is a mixture of solid and liquid, and an atomization medium supply channel that atomizes the fuel, the fluid fuel supply channel The atomizer and the atomizing medium supply flow path intersect with each other, and the fuel atomizer is equipped with a plurality of nozzles that mix the fuel and the atomizing medium to form a spray stream of ejected fuel, or a fuel atomizer that only processes the above fuel. In a fluid fuel combustion burner having a fuel injection atomizer provided with a plurality of nozzle holes for pressurized jetting to form a spray stream of fuel, the plurality of nozzle holes are divided into at least two or more groups and arranged. ,
This is achieved by configuring fuel spray atomizers in which the positions of the nozzle holes arranged adjacent to each other in each group are arranged at different radial distances from the axial center or the vicinity of the axial center of the atomizer. be done.

In the fuel spray atomizer of the present invention, the positions of the nozzle holes in each group divided into at least two or more groups are arranged on concentric circles having different radii around the axis of the atomizer, or It is preferable that the positions of the ejection holes in each group are arranged in fuel spray atomizers on concentric circles having different centers for each group.

In the fuel injection atomizer of the present invention, the nozzle holes are arranged in at least two or more groups, and the nozzle holes arranged adjacent to each other in each group are arranged near the axis of the atomizer. It is more preferable to have a fuel spray atomizer in which the fuel spray atomizer has an ejection hole formed at the center by sequentially opening in the same direction as the swirling direction of the combustion air from the circumference with a large radius to the circumference with a small radius.

[For production]

According to the opening arrangement of the mixing nozzle provided in the atomizer of the NOx and soot and dust reduction burner according to the present invention, the fuel becomes concentrated in the burner flame, and due to low NOx combustion, N
Without losing the characteristics of a burner equipped with a conventional low NOx atomizer that can reduce Ox In addition, since the combustion air enters and is mixed and diffused in a very short period of time, rapid ignition of the fuel is possible in the vicinity of the atomizer of the burner. When rapidly heated by such rapid ignition, most of the carbon content in the ejected droplets of the fuel spray is instantly thermally decomposed.
The combustion reaction is greatly accelerated. As a result, the combustion is essentially equivalent to the combustion of fuel oil with a low residual carbon content (the heating rate is an order of magnitude different from the normal heating rate), and the flame-retardant heavy The flammability of the oil will be further improved.

〔Example〕

An embodiment of the present invention will be described below in more detail based on the drawings.

(Example 1) FIG. 1 and FIG. 2 (a), (b), and (c) show an example of the structure of the atomizer of the NOx and soot/dust reduction burner of the present invention. Figure 1 is a plan view of the atomizer viewed from the furnace side, showing the arrangement of the mixing jet holes for atomizing medium and fuel;
Figures (a), (b), and (c) show mixing nozzle holes 10α, 10
It is a cross-sectional view of the β and 10γ parts viewed from a plane passing through the axis of the atomizer.

As shown in FIGS. 2(a), 2(b), and 2(c), the atomizer according to the present invention is comprised of an atomizer chip body 1, an atomizer back plate 4, and a cap nut 11. The fuel 2 passes through a plurality of fuel communication pipes 5 that are opened in the back plate 4 of the atomizer.
It enters the fuel distribution channel 7 of the chip body 1 and enters the fuel supply hole 9α.
, 9β, 9γ to each mixing nozzle 10α, 10β, 10
γ, and is supplied to mixing orifices 10α, 10β, 10γ that atomize the fuel and inject it into the furnace.

The fuel atomization medium 3 is fed to the atomization medium distribution channel 8 located at the center of the upstream side of the chip body 1 through an atomization medium communication pipe 6 that opens on a plane passing through the central axis of the back plate 4. , are supplied to each of the mixing nozzles 10α, 10β, and 10γ. The fuel 2 and the atomization medium 3 are supplied to each mixing nozzle 10α.
, 10β, and 10γ, the particles are atomized into atomized particles and ejected from the atomizer. The fuel spray stream mixes with combustion air and burns, forming a flame.

In the atomizer of the present invention, for example, as shown in FIG. 1, a total of six mixing ejection holes 10α, 10β, and 10γ are distributed on a circumference with different radii centered on the axis of the atomizer. In other words, it is divided into two groups of three, and the three mixed nozzles 10α in the same group
, 10β, and 10γ are adjacent to each other and open facing the furnace side. This is an attempt to reduce the NOx emission concentration by dividing the burner flame into two parts to vary the fuel concentration in the fuel jet flow. Three mixing orifices 10α, 10β, 10 for each group of fuel orifices
As shown in Fig. 1, γ is not on the same circumference, but on a circumference with different diameters for φD1, φD2, and φD, and the mixing jet holes 10γ are arranged in order of increasing circumferential diameter.
, 10β, and lOα. Note that the opening positions of the mixing jet holes 10α, 10β, and 10γ in the circumferential direction are the same in each group.

The spreading angles θs1, θ3 .
and θs3 are different as shown in FIG. 2, and the spreading angle of the mixing nozzle has a relationship of θS□, θ8□, and θ3°. In addition, the merging angle of the fuel supply holes 9α, 9β, 9γ and the mixing nozzle holes 10α, 10β, 10γ is
θ, 1, θyo2 for 0α, lOβ, 10γ. θ1.
The relationship is θ, 1 x θ, 2 x θ, and so on.

(Example 2) As shown in Fig. 3, in this example, the above-mentioned Fig. 1,
As in Example 1 shown in FIG. 2, six mixing nozzles 1
0γ10γ2.10γ1.10γ10β2,10β
2, three mixing nozzle holes IOγ2 shown on the right side,
A group of lOβ, and three mixing vents 1 shown on the left.
It is divided into two groups: 0γ3.
10γ is arranged on the circumference φD□ with a small diameter, that is, on the inside when viewed from the central axis of the chip body 1, and the mixing nozzle lOβ and 10β are located in the middle of each of the two groups.
2 is arranged so as to open above the large diameter circumference φD, that is, to the outside when viewed from the central axis of the chip body 1.

(Example 3) As shown in FIG.
The mixing jet holes 10β□, 10β2 and 10β1°10β4 located on the -right outer side are opened on the outer circumference when viewed from the central axis of the chip body 1. It was placed in

FIG. 5 shows the flow state of the fuel spray from each mixing nozzle in the atomizer having the structure shown in FIGS. 1 and 2 illustrated in Example 1 of the present invention. In the atomizer of the present invention, each of the mixing nozzles 10α, 1 in the same group
Since 0β and 10γ are opened on non-concentric circles, the swirling combustion air A flows into the fuel spray flow 12 as shown by the arrow.
It flows into the spray streams of α and 12β, 12β and 12γ, and further between 12γ and 12α and is mixed well. However, in conventional atomizers as shown in FIG. 9 and FIG. , the mixing of the combustion air with the fuel droplets forming the spray stream is delayed, resulting in incomplete combustion and the generation of soot and dust.

FIG. 6 schematically shows the distribution of the dispersed flow rate (droplet flux per unit time/unit area) of fuel spray droplets with respect to the distance in the circumferential direction of the atomizer chip. As shown in Figure (a), the spray flow 12α of each fuel
, 12β, and 12γ, three peaks can be seen in the dispersed flow rate of fuel jet droplets corresponding to each of the mixing nozzles 10α, 10β, and 10γ. on the other hand,
In the conventional atomizer shown in FIG. 6(b), the spray streams 12 of each fuel come close to each other until they interfere with each other, so the dispersed flow rate of the fuel spray droplets tends to gather at the intermediate mixing nozzle 10. Mixing and diffusion of the combustion air becomes insufficient, resulting in the generation of soot and dust.

FIG. 7 shows the flue oxygen concentration (%) during heavy oil combustion using the atomizer of the present invention shown in FIGS. 1 and 2 and the conventional atomizer shown in FIGS. ) and the soot and dust concentration (■/Nrn'). As shown in the figure, when the atomizer of the present invention is used, the soot and dust concentration in the exhaust gas is extremely low over the entire range of flue oxygen concentration, indicating that there is an excellent soot and dust reduction effect. This is because combustion air is sufficiently supplied between the fuel spray flows 12α, 12β, and 12γ from each of the mixing nozzles 10α, 10β, and 10γ, so that the flame is ignited very close to the tip body 1 of the atomizer. This is thought to have accelerated the rapid thermal decomposition of the fuel. The burner using the atomizer of the present invention exhibits an excellent effect on improving burnout in a boiler furnace, and promotion of combustion in the very early stage of combustion is an extremely important factor.

FIG. 8 shows the flue oxygen concentration (%) during heavy oil combustion using the atomizer of the present invention shown in FIGS. 1 and 2 and the conventional atomizer shown in FIGS. ) and the NOx concentration in exhaust gas (084% conversion, ppH). As is clear from the figure.

The atomizer of the present invention has each mixing ejection hole 10α, 10β,
It can be seen that although the combustion air is allowed to flow between the fuel spray flows 12α, 12β, and 12γ from lOγ, the NOx concentration in the exhaust gas can be reduced almost to the same extent as in the conventional atomizer. In other words, the burner using the atomizer of the present invention has an excellent property of reducing the concentration of NOx in the exhaust gas through concentrated combustion through flame division, and at the same time can significantly reduce the amount of soot and dust generated. I understand that.

In the above examples, only the combustion of heavy oil fuel was explained, but it is also effective for high efficiency combustion of other liquid fuels (such as light oil) or slurry fuels with low NOx and low soot. be. Slurry fuel is a fluidized fuel made by adding pulverized solid fuel and liquid, and there are the types shown below.

CWM (coal, water mixed fuel) COM (coal, heavy oil mixed fuel) CMM (coal, methanol mixed fuel) PWM (petroleum coke or pitch and water mixed fuel) CTM (coal, tar mixed fuel) SOM (solvent refined coal and mixed fuel of heavy oil), etc.

However, when such a slurry fuel is used, the fuel and atomization medium mixing injection hole of the atomizer needs to be made of a wear-resistant material.

〔Effect of the invention〕

As described above in detail, the fluid fuel combustion burner having the atomizer of the present invention can significantly reduce the soot and dust concentration and improve combustion efficiency without increasing the NOx concentration in the exhaust gas.

This burner characteristic means that the types of fluid fuels that can be used can be expanded in the same boiler furnace, and the economic effect is extremely large. For example, even if it is an inexpensive fuel with a high residual carbon or nitrogen content, or whose carbon crystal structure is extremely flame-retardant, it will still produce as low NO as conventional fuel.
Since combustion can be carried out at x level and the generation of soot and dust can be significantly reduced, it is possible to further reduce operating costs in the boiler furnace.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the atomizer exemplified in Example 1 of the present invention as seen from the inside of the furnace, and Fig. 2 (,), (b), (
c) is a sectional view of the atomizer shown in FIG. 1 at α, β, and γ positions; FIGS. 3 and 4 are plan views of the atomizers illustrated in Examples 2 and 3 of the present invention as seen from inside the furnace; 5 is a schematic diagram showing the state of the fuel spray flow by the atomizer shown in FIG. 1, FIG. 6(a) is a diagram showing the dispersed flow rate of fuel spray droplets when the atomizer shown in FIG. Figure 6 (b
) is a diagram showing the dispersion flow rate of fuel spray droplets by a conventional atomizer, and Figure 7 is a diagram showing the soot and dust concentration in exhaust gas and flue oxygen concentration when using the atomizer of the present invention shown in Figure 1 and the conventional atomizer. Figure 8 is a graph showing a comparison of the NOx concentration in the exhaust gas when the atomizer of the present invention shown in Figure 1 and the conventional atomizer are used. Figure 9 is the inside of the furnace of the conventional atomizer. FIG. 10 is a sectional view taken along line II in FIG. 9. 1... Chip body 2... Fuel 3... Atomization medium 4... Back plate 5... Fuel communication pipe 6... Atomization medium communication pipe 7... Fuel distribution channel 8. ...Atomization medium distribution channel 9.9α, 9
β, 9γ...Fuel supply hole 10.10α, 10β, 10
γ, 10β□ to 10β10γ, to 10γ4...Mixing jet hole 11...Cap nut 12.12α, 12β, 12γ...Spray flow θs1, θ
s2, θS,... Spreading angle θ of the mixing nozzle, θ
1□, θ1. ... Merging angle A ... Combustion air swirling direction

Claims (1)

[Scope of Claims] 1. A fluid fuel supply channel that supplies a liquid fuel or a fluidized fuel that is a mixture of solid and liquid, and an atomization medium supply channel that atomizes the fuel; The flow path and the atomization medium supply flow path intersect, and the fuel spray atomizer is provided with a plurality of ejection holes that merge and mix the fuel and the atomization medium to form a spray stream of ejected fuel, or only the above fuel. In a fluid fuel combustion burner having a fuel spray atomizer provided with a plurality of nozzle holes for pressurized jetting of fuel to form a spray stream of fuel, the plurality of nozzle holes are divided into at least two or more groups and arranged. and the positions of the nozzles arranged adjacent to each other in each group,
A NOx and soot and dust reduction burner comprising fuel spray atomizers arranged at different radial distances from the axis of the atomizer or the vicinity of the axis. 2. In the fuel spray atomizer as set forth in claim 1, the positions of the nozzle holes in each group, which are divided and arranged into at least two or more groups, are arranged in concentric circles with different radii centered approximately on the axis of the atomizer. Arrange the vents on the circumference or position the vents in each group.
A NOx and soot reduction burner characterized by having fuel spray atomizers arranged on concentric circles with different centers for each group. 3. In the fuel spray atomizer according to claim 1 or 2, the positions of the nozzle holes arranged in at least two or more groups and arranged adjacent to each other within each group. The fuel spray is formed by sequentially opening in the same direction as the swirling direction of the combustion air from the circumference of a circle with a large radius to the circumference of a circle with a small radius, centering on the vicinity of the axis of the atomizer, to form nozzle holes. A NOx and soot and dust reduction burner, characterized in that it has an atomizer.