JPS60218505A - Burner - Google Patents

Abstract

PURPOSE:To contrive reduction of fuel NOx and thermal NOx and miniaturization of a furnace, by a method wherein injection holes whose injection angles are different from each other are provided on the tip of a burner, a widen out frame holder and a deflected ring are provided on the tips of the inside and outside sleeves and a reducing region and a oxidizing region are formed on the tip of the burner. CONSTITUTION:Fine fuel particles from an outside injection hole 30 is engulfed in a flame holding vortex to be generated in the inside of a flame holder 36 and developed into an external flame brim 41. Combustion is performed through secondary air C to be supplied from a secondary air hole 18 and turned into an oxidizing region 39. On the one hand, as supply air becomes only primary air B, fuel from an intermediate injection hole 31 and an inside injection hole 32 is turned into a fuel surplus region and a reducing region. As NOx based on oxidation of content of N and an intermediate product dissolving the NOx exist within the reducing region and are kept at the high temperature by the oxidizing region 39, reducing reaction is advanced and the NOx is decreased. On the other hand, tertiary air D is made into a locus to be shown by an arrow D through forced turning by a deflected ring 37, a tertiary register 19 and a tertiary vane 20, supplied after disappearance of the NOx and burnt in a complete combustion region 42.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a mixed coal fuel (Co
al Oil Mixttbr - abbreviated as COM)
, coarse powder coal, mixed coal fuel (CoalW
The present invention relates to a combustion device that exclusively burns or co-combusts liquid fuel such as ater pJixturg (abbreviated as CWM), and particularly relates to a combustion device that reduces nitrogen oxides (hereinafter referred to as NOx) in exhaust gas.

[Background of the invention]

NOx generated during the combustion of liquid fuel is thermal ('r
AgrrILaL ) NOx and 7 = L - L (F
tLgZ ) NOx It is roughly divided into
x is generated by the oxidation of nitrogen in the combustion air, and is highly dependent on flame temperature, with the higher the temperature, the more thermal NOx is generated. On the other hand, fuel NOx is generated when the nitrogen content in the fuel is oxidized, and is highly dependent on the oxygen concentration in the flame, and the N content in the seed fuel that contains excess oxygen tends to become fuel NOx.

Combustion methods to suppress the generation of NOx include a multistage combustion method in which combustion air is divided into multiple stages and injected, and an exhaust gas recirculation method in which combustion exhaust gas with a low oxygen concentration is mixed into the combustion area. All of these low NOx combustion methods are aimed at suppressing the generation of thermal NOx by lowering the temperature of the combustion flame through low oxygen combustion.

However, between thermal NOx and fuel NOx,
It is thermal NOx that can suppress the amount of NOx generated by lowering the combustion temperature, and the amount of fuel NOx generated has little dependence on the combustion temperature.

Therefore, although conventional combustion methods aimed at lowering the flame temperature are effective for the combustion of liquid fuels such as heavy oil with a relatively low N content, nearly 80% of the NOx generated is
It has little effect on the combustion of eOM, CWM, etc., which are NOx.

Figures 1 and 2 show conventional combustion equipment that exclusively burns and co-fires liquid fuel. Figure 1 is a vertical cross-sectional view of the conventional combustion equipment, and Figure 2 is an enlarged view of section A in Figure 1. It is a detailed view of a burner nozzle.

In Figures 1 and 2, 1 is the furnace wall, 2 is the furnace, and 3 is the furnace wall.
1 is a burner throat bored in the furnace wall 1, 4 is a burner placed in the burner throat 3, and 5 is a wind box.

And inside this wind box 5 and burnus throat 3
Inside, a primary air passage 8 is formed by a partition plate 6 and an inner sleeve 7.
and a secondary air passage 9, and are divided into a secondary air passage 9 and a tertiary air passage 12 by a partition plate 10 and an outer sleeve 11.

In this structure, the primary air B is supplied to the primary air passage 8 from the primary air intake port 13 provided in the inner sleeve 7, and the amount of primary air is adjusted by the secondary damper 14 to The air is supplied into the furnace 2 through the primary air port 15 .

The secondary air C is supplied from the secondary register 16 to the secondary air passage 9, and after being given a swirling force by the secondary vane 17, is supplied from the secondary air port 18 into the furnace 2.

The tertiary air passage is connected to the tertiary air passage 12 by the tertiary register 19.
It becomes a swirling flow by the tertiary vane 2o, and is supplied into the furnace 2 from the tertiary air port 21.

On the other hand, as shown in FIG. 2, the burner 4 is provided with a fuel passage 22 and a steam passage 23, and a nozzle tip 24 is fixed to the tip thereof by a cap 25. This nozzle tip 24 is connected to a threaded portion 26 provided on the cap 25.
The injection hole 2 is fixed from the fuel groove 27 to the inside thereof.
8 is supplied with fuel from the fuel passage 22.

However, in such conventional combustion devices, a Y-jet type nozzle tip 24 is used for two-fluid spraying in which fuel in the fuel passage 22 is atomized by steam in the steam passage 23. The injection direction 29 of the fuel 24 is uniform in the angle θ direction, and the effect of reducing NOx is about 5 to 10% at most, and it is not possible to significantly reduce NOx.

This is because the injection direction 29 from the fuel injection hole 28 is limited within a certain range, so that an excessive amount of secondary air C1 and tertiary air is supplied to the combustion zone in addition to the primary air amount for combustion.
This is because the oxidation of nitrogen in the fuel (2-L NO) and the oxidation of N2 in the air due to high temperatures (thermal NOX) proceed sufficiently.

Then, for this fuel NOx, a primary combustion zone is formed with combustion air that is less than the theoretical air amount, and a secondary combustion zone is formed by supplying the insufficient combustion air to the wake of this zone. The reduction was attempted using the so-called two-stage combustion method.

On the other hand, thermal NOx has been reduced by a so-called exhaust gas recirculation method in which exhaust gas generated by combustion is circulated and supplied to the burner section again.

Tokoroka, 7Uel If a two-stage combustion method is adopted to prevent NOx, the furnace such as a boiler will become larger, and the structure of the combustion zone will become complicated due to the provision of an after-air port to supply the insufficient combustion air. There are drawbacks.

Furthermore, if an exhaust gas recirculation method is adopted to prevent thermal NOx, the temperature of the combustion gas decreases, which has the drawback of increasing the size of a furnace such as a boiler.

[Purpose of the invention]

The present invention aims to eliminate such conventional drawbacks,
The purpose is to provide a combustion device that can reduce NOx to 7 uel and thermal NOx by self-denitrification combustion, and can downsize the entire furnace.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides injection holes with different injection angles at the tip of the burner, and also provides a flared frame holder and a deflection ring at the tips of the inner sleeve and the outer sleeve. A reduction zone with excess fuel and an oxidation zone with excess air are formed.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

3 to 6 show a combustion device according to an embodiment of the present invention, FIG. 3 is a longitudinal sectional view of the combustion device, and FIG. 4 is a side view of the nozzle, which is an enlarged view of section E in FIG. 3. 5 is a sectional view taken along the line v-v in FIG. 4, and FIG. 6 is an explanatory diagram showing the flow state of combustion air.

In addition, in FIGS. 3 to 6, numerals 1 to 27 are the same as those of the conventional device.

30.31.32 is an outer injection hole, an intermediate injection hole, and an inner injection hole with different injection angles provided in the nozzle chip 24;
3.34.35 outer, middle and inner injection holes 30.3
1. Injection direction from 32, 36 is a flared frame holder provided at the tip of the inner sleeve 7, 37 is a deflection ring provided at the tip of the outer sleeve 11, 38 is a reduction zone, 39 is an oxidation zone, 40 is a A flame-holding vortex, 41 is the flame outer edge, 42 is a complete combustion zone, and 43 is a recirculation flow.

In such a structure, the difference between the conventional combustion apparatus shown in FIGS. 1 and 2 and the combustion apparatus of the present invention shown in FIGS. 3 to 6 is that in the conventional combustion apparatus, the nozzle of the burner 4 is As shown in FIG. 2, the injection hole 28 in the tip 24 is approximately constant at the injection angle θ, and the inner sleeve 7 and the outer sleeve 11 are arranged around the outer periphery of the burner 4.
In the combustion apparatus of the present invention, as shown in FIG. 5, the nozzle tip 24 of the burner 4 has an outer injection hole 30. An intermediate injection hole 31 and an inner injection hole 32 are bored, and an inner sleeve 7 is provided on the outer periphery of the burner 4, as shown in FIGS. 3 and 6.
A frame holder 36 is disposed at the tip of the outer sleeve 11, and a deflection ring 37 is disposed at the tip of the outer sleeve 11.

That is, as shown in FIG. 4, the nozzle chip 24 has four outer injection holes 30, four intermediate injection holes 31, and three inner injection holes.
Although the number of injection holes is one, the number of injection holes does not matter, and as shown in FIG. have different injection angles in the injection direction 35.

These outer, middle, and inner injection holes 30, 31.
32, as shown in FIG.
3 are connected, from the fuel groove 27 to each injection hole 30.31.3
As shown in FIG. 3, fuel and steam are sprayed into the furnace 2 from an outer injection hole 30, an intermediate injection hole 31, and an inner injection hole 32.

On the other hand, on the outer periphery of the burner 4, as shown in FIGS. 3 and 6, a frame holder 36 and a deflection ring 37 are provided at the tips of the inner sleeve 7 and the outer sleeve 11.

Therefore, the fuel sprayed from the burner 4 is transferred to the outer injection hole 3.
0, the injection angles from the intermediate injection hole 31 and the inner injection hole 32 are different as shown in the injection direction 33, 34, and 35, and the fine particles from the outer injection hole 30 are generated inside the flame holding vortex 40 ( 6), a flame is formed on the frame holder 36 and develops as a flame outer edge 41.

In this way, the fuel from the outer injection hole 30 is transferred to the secondary air port 18.
Combustion is carried out by the secondary air C supplied from the oxidation zone 39.

On the other hand, fuel from the intermediate injection hole 31 and the inner injection hole 32 is heated and evaporated in this oxidation region 39, but since only the primary air B is supplied to this region, it becomes a fuel excess region and intermediate products are generated. This becomes a reduction zone 38.

Therefore, in this reduction zone 38, NOx due to oxidation of N,
Since there is an intermediate product that decomposes it and the temperature is maintained at high temperature by the oxidation zone 39, the reduction reaction proceeds rapidly, resulting in a reduction of Now.

On the other hand, the tertiary air has deflection/g 37 and tertiary resistor 1.
9. Due to the strong rotation by the tertiary page 720, the trajectory shown by the arrow is formed, and after the NOx disappears, it is supplied and burned in the complete combustion zone 42.

That is, Figure 6 shows primary, secondary, and tertiary air (B.

As shown in the flow diagrams C and D), the secondary air C1 and the tertiary air are supplied outward by the frame cap 36 and the deflection ring 37. The flame-holding vortex 40 formed inside suppresses diffusion to the outside,
At the same time as the ignition occurs, a high temperature reduction region 38 (FIG. 3) is formed in the vicinity (tip) of the burner 4. This high temperature reduction area 38
NOx is reduced to N2 in the gas phase by radicals such as NH2 and CN and reducing intermediate products such as CO. In other words, by preventing fuel diffusion with the flame cap 36, the high-temperature reduction zone 38 can be brought closer to the tip of the burner 4 than in conventional combustion devices, and secondary air is Even if the C1 tertiary air is injected, the high temperature reduction region 38 is formed closer to the burner 4 than the mixing point of these airs, making it possible to perform good gas phase reduction.

Further, on the downstream side of the high temperature reduction zone 38, the secondary air C is swirled by the secondary register 16 and the secondary vane 17, and the tertiary air is swirled by the tertiary register 19 and the tertiary vane 20, so that the high temperature reduction zone 38 is By supplying the secondary air C and the tertiary air to the high temperature reduction zone 38, it is possible to supply the secondary air C and the tertiary air separately from the high temperature reduction zone 38.

In this case, the pressure of the tertiary air chamber is, for example, tertiary register 1
It is preferable to operate at 120 mAy or more on the upstream side of 9, and the air volume ratio of tertiary air and secondary air C is 4:1.
It is effective to do so.

As mentioned above, the tertiary air is injected into the furnace 2 at a wide injection angle at the burner throat 3 by maintaining a strong swirling force and an appropriate amount of air. A recirculation flow 43 is formed in the reduction zone 38, and this high-temperature reduction zone 38 is formed near the tip of the burner 4. In particular, the high-temperature reduction zone 38 and the secondary air C
Also, the mixing of tertiary air is slight near the tip of the burner 4, and therefore good gas phase reduction can be carried out.

Further, a complete combustion zone 43 on the downstream side of the high temperature reduction zone 38
In this case, the injection energy of the secondary air C1 and the tertiary air also decreases, and unburned matter is combusted.

In this way, in the combustion device according to the embodiment of the present invention,
Since a stable flame can be formed near the flame holder 36 by the flame-holding vortex 40 and a reduction zone 38 can be formed, the NOx decomposition efficiency can be increased and NOx can be reduced.

In addition, since self-denitrification combustion can be performed with a single burner 4, the furnace can be made smaller.In particular, low NOx combustion occurs immediately after ignition of the burner 4, so NOx is generated when the boiler is started or when the load changes. can be significantly reduced.

〔Effect of the invention〕

In the present invention, injection holes with different injection angles are provided at the tip of the burner, and a frame holder that widens toward the end and a deflection angle are provided at the tips of the inner sleeve and the outer sleeve.

By creating a reduction zone with excess fuel and an oxidation zone with excess air at the tip of the burner, it is possible to reduce fuel NOx and thermal NOx through self-denitrification combustion, and it is also possible to downsize the furnace. .

[Brief explanation of drawings]

Figures 1 and 2 show a conventional combustion device, where Figure 1 is a longitudinal sectional view of the combustion device, Figure 2 is an enlarged sectional view of section A in Figure 1, and Figures 3 to 6. 3 shows a combustion device according to an embodiment of the present invention, and FIG. 3 is a longitudinal sectional view of the combustion device;
Figure 4 is an enlarged side view of part 6 in Figure 3, and Figure 5 is the 4th section.
FIG. 6 is an explanatory diagram showing the flow state of combustion air. 3... Burner throat, 4... Burner, 7... Inner sleeve, 8... Secondary air passage, 9... Secondary Air passage, 11...
・Outer sleeve, 12...Tertiary air passage, 30
．． 31.32... Injection hole, 36... Frame holder, 37... Deflection ring 1.38.
...Reduction area, 39...Oxidation area. Figure 1 Figure 2 V Season

Claims (1)

[Claims] A burner is disposed within a burner throat, and an inner sleeve and an outer sleeve are provided between the burner throat and the burner to define a primary air passage, a secondary air passage, and a tertiary air passage, and the fuel from the burner is combusted. The tip of the burner is provided with injection holes with different injection angles, and the tips of the inner sleeve and outer sleeve are provided with an unfinished flame holder and a deflection ring, and the tip of the burner is provided with a reduction zone for excess fuel and an oxidation zone for excess air. A combustion device characterized in that: