JP2002267109A - Method for feeding air-fuel mixture in pulverized coal burner and square nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulverized coal burner 3 capable of feeding air-fuel mixture of pulverized coal fuel having different fuel-air ratios, capable of suppressing an NOx generating amount, and air through one square nozzle 6. SOLUTION: A density separator 8 is provided in the square nozzle 6. A relation between height H1 of the density separator 8 and height H of the square nozzle 6 is set to H1=0.5×H, and a relation between width W1 of the density separator 8 at an end face 13 and width W of the square nozzle 6 is set to W1=0.7×W. The pulverized coal burner 3 is capable of feeding fuel-air mixture of pulverized coal fuel and air, having different fuel-air ratio, capable of suppressing an NOx generating amount by one square nozzle 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized coal burner for use in, for example, a power boiler or a chemical industrial furnace.
In addition, the present invention relates to a method for supplying a gas mixture in a square nozzle provided in a pulverized coal burner in a power boiler, a chemical industrial furnace, or the like.

[0002]

2. Description of the Related Art For example, a furnace of a power generation boiler is provided with a pulverized coal burner for feeding a mixture of pulverized coal fuel and air to a furnace through a square nozzle. In pulverized coal combustion, it is known that there is a predetermined relationship between the air-fuel ratio, which is the ratio of the amount of fuel to the amount of air in the air-fuel mixture, and the amount of nitrogen oxide (NO _x ) generated and combustion performance. That is, pulverized coal concentration is uniform ignition in an air-fuel ratio of the high richer obtained, the air-fuel ratio of the pulverized coal concentration is less lean side can be suppressed NO _x emissions. For this reason, a distributor is provided in the fuel supply passage, air-fuel ratios different in air-fuel ratio are individually supplied to the square nozzles, and air-fuel mixtures having different shadings are individually supplied to the furnace from a plurality of square nozzles. I have.

[0003]

In [0005] the prior art described above, it is pulverized coal burner having a plurality of rectangular nozzles in order to suppress the NO _x generation amount, undeniable size of the furnace, including the support structure There was nothing. By arranging a device that separates shading in the nozzle, a mixture of air-fuel ratios with different air-fuel ratios can be delivered by one nozzle, and the existing pulverized coal burner is modified to reduce the size of supporting structures, etc. Can be achieved. Therefore, at present, the appearance of the equipment can be set the contrast of the fuel is desired to suppress the NO _x generation amount with respect to one rectangular nozzle.

[0004] The present invention has been made in view of the above circumstances, it is possible to deliver a mixture of air-fuel ratio of the pulverized coal fuel and air different can suppress the NO _x generation amount in one of the rectangular nozzle It is intended to provide a pulverized coal burner. The present invention has been made in view of the above circumstances,
And to provide a mixture delivery method in a rectangular nozzle which can suppress the NO _x generation amount in one of the rectangular nozzle.

[0005]

To achieve the above object, a pulverized coal burner according to the present invention comprises a pulverized coal burner for feeding a mixture of pulverized coal fuel and air to a furnace through a square nozzle. A square density separator is provided inside the square nozzle, and the density separator has a square shape disposed at the center of the square nozzle, and the downstream end in the flow direction with the upstream end face in the flow direction of the mixture as the apex. And a rectangular fluid inlet portion is formed at the downstream end face of the mixture in the flow direction, and a rectangular fluid outlet is formed at the downstream end face of the mixture in the flow direction. The fluid inlet and the fluid outlet are communicated by a flow path, and the relationship between the height H1 of the density separator and the height H of the square nozzle is H1 = 0.5 × H, and the downstream end face in the flow direction of the air-fuel mixture. The relationship between the width W1 of the density separator and the width W of the square nozzle at W1 is W1 = 0.7 × And said that the content was.

The relationship between the height H1 of the density separator and the height H of the square nozzle is set within a range of ± 15%,
The relationship between the width W1 of the density separator and the width W of the square nozzle is set within a range of ± 15%. Also,
The relationship between the distance 1 from the downstream end face of the air-fuel mixture in the flow direction of the air-fuel mixture to the tip of the square nozzle and the height H of the square nozzle is 1 / H = 1.0 to 2.5. Also, 1 / H = 1.5.

[0007] To achieve the above object, a method for feeding a mixture of air in a square nozzle according to the present invention is a method for feeding a mixture of pulverized coal fuel and air to a furnace through a square nozzle. Using the density separator having the above separation efficiency η, the air-fuel mixture is supplied with the air-fuel ratio (A / C), which is the ratio of the fuel amount to the air amount of the mixture supplied to the square nozzle, being 2.0 to 3.0. It is characterized by.

[0008]

1 is a sectional view of a pulverized coal burner according to an embodiment of the present invention, FIG. 2 is a sectional view of a square nozzle, and FIG. 3 is a line III-III in FIG. View, FIG. 4 shows FIG.
FIG. 5 is a graph showing the relationship between the width of the density separator, the separation efficiency, and the pressure loss.

As shown in FIG. 1, a boiler main body 1 is provided with a burner-like box 2, and the burner-like box 2 is provided with a pulverized coal burner 3. An air-fuel mixture of pulverized coal fuel and primary air is sent to the pulverized coal burner 3 through a pulverized coal pipe 4, and a kicker block 5 is provided above a bend portion outlet of the pulverized coal pipe 4. The air-fuel mixture from the pulverized coal pipe 4 is supplied to a furnace 7 through a square nozzle 6. The part of the square nozzle 6 facing the furnace 7 (tip part)
Is provided with a square density separator 8.
Are fixed in the square nozzle 6 by fixing brackets 9.

An air-fuel mixture is sent from the pulverized coal pipe 4, and the pulverized coal is densely concentrated at the bend portion due to centrifugal force, but is dispersed by the kicker block 5 and guided to the density separator 8. In the density separator 8, the air-fuel ratio (A / C), which is the ratio of the amount of fuel (kg coal) to the amount of air (kg air) inside the square nozzle 6, is made different between the central portion and the peripheral portion. That is, as shown in FIG. 2, the air-fuel mixture feeding method of the square nozzle according to the present embodiment is configured to supply the air-fuel mixture having an air-fuel ratio of, for example, 2.0 to 3.0 from the pulverized coal pipe 4, and to perform density separation. The air-fuel mixture having a lean air-fuel ratio (for example, A / C is about 3.0 to 5.0) is formed at the center of the square nozzle 6 by using the heater 8, and the rich air-fuel ratio (for example, A / C is 1.4 to 4.0) is formed around the center. The mixture of 2.1) is formed.

As a result, a rich air-fuel mixture is ignited uniformly around the square nozzle 6 and a good flame is obtained.
Mixture of lean air-fuel ratio is flame obtained by igniting and burning in transfer fire surrounding the flame, it is possible to obtain a combustion state which suppresses NO _x emissions. Therefore, it is possible to pulverized coal burner 3 for supplying air-fuel mixture can be suppressed NO _x generation amount in one of the square nozzle 6, to the existing rectangular nozzle for supplying separately a mixture of different air-fuel ratio With easy modification, it is possible to provide a square nozzle capable of supplying an air-fuel mixture whose periphery is dark and whose center is thin.

The shape of the density separator 8 will be described in detail with reference to FIGS.

As shown in the figure, the density separator 8 has a square shape disposed at the center of the square nozzle 6, and has an end face 10 on the upstream side (right side in FIG. 2) in the flow direction of the air-fuel mixture as a vertex. Inclined section 1 whose cross-sectional shape gradually increases toward the downstream side in the flow direction
1 is provided. The end face 10 has a square fluid inlet 1
2 is formed, and the downstream side in the flow direction of the mixture (left side in FIG. 2)
A rectangular fluid outlet 14 is formed on the end face 13.
The fluid inlet 12 and the fluid outlet 14 are connected by a channel 15 having a square cross section. The end of the sectional shape gradually enlarged by the inclined portion 11 has the same shape as the shape of the end face 13, and the height of the density separator 8 is the height at the end face 13.
H1.

With the provision of the density separator 8, both the pulverized coal and the air are biased toward the outer periphery of the square nozzle 6 by the wedge effect of the inclined portion 11, and a part of the mixture is supplied to the fluid inlet 1.
2 to the fluid outlet 14 through the flow path 15. The air biased toward the outer peripheral portion gradually returns to the central portion, but the pulverized coal is difficult to return. Therefore, on the downstream side of the density separator 8, a peripheral portion is rich (rich) and a central portion is thin (lean). .

The relationship between the shapes and dimensions of each member will be described with reference to FIGS.

As shown in FIG. 2, the relationship between the height H1 of the density separator 8 and the height H of the square nozzle 6 is set to H1 = 0.5 × H. As shown in FIG. 3, the relationship between the width W1 of the density separator 8 on the end face 13 and the width W of the square nozzle 6 is W1 = 0.7.
× W.

The relationship between the height H1 of the density separator 8 and the height H of the square nozzle 6 is ± 15% of the relationship described above.
The relationship between the width W1 of the density separator 8 and the width W of the square nozzle 6 is set within a range of ± 15% with respect to the above-described relationship.

By setting as described above, the pressure loss can be suppressed, the vortex does not occur on the upper and lower surfaces and the side surfaces on the downstream side of the concentration separator 8, and the pulverized coal is not entrained. Can be satisfactorily secured.

As shown in FIG. 2, the relationship between the distance l from the end face 13 of the density separator 8 to the tip 6a of the square nozzle 6 and the height H of the square nozzle 6 is 1 / H = 1.0. To 2.5. At this time, it is preferable that 1 / H = 1.5. At this time, if the distance 1 from the end face 13 to the tip 6a of the square nozzle 6 is short, the concentration distribution of the pulverized coal occurs, but the flow rate of the air-fuel mixture becomes uneven, and the tip end of the square nozzle 6 from the end face 13 If the distance 1 to 6a is long, the flow rate of the air-fuel mixture becomes uniform, but no concentration distribution of pulverized coal occurs. Therefore, 1 / H = 1.
By setting 5, it is possible to obtain a state in which the flow rate of the air-fuel mixture is uniform and only the concentration distribution of pulverized coal occurs.

The relationship between the width W1 of the density separator 8 and the separation efficiency η and the pressure loss will be described with reference to FIG. Here, the separation efficiency η is the ratio of the air-fuel mixture in the surrounding area on the downstream side of the density separator 8 to the weight flow rate (kg coal / h) of the total pulverized coal per unit time of the air-fuel mixture on the upstream side of the density separator 8. It is the ratio of the weight flow rate of pulverized coal (kg coal / h) per unit time. That is, η = the weight flow rate of the mixture in the surrounding area (kg coal /
h) / Weight flow rate of total pulverized coal (kg coal / h) x 100 (%). The larger the separation efficiency η, the denser the air-fuel mixture in the surrounding area, and the target optimum separation efficiency η is, for example, 70%.

When setting the width W1 of the density separator 8, the width W of the square nozzle 6 is set to about 420 mm and the height H is set to about 490 mm.
The height H1 of the density separator 8 is set to 0.5 × H.
FIG. 5 is a graph showing the results obtained by measuring the separation efficiency η and the pressure loss using a density separator having a width W1 of various types.

As can be seen from the figure, the separation efficiency η increases as the width W1 of the density separator increases, and is about 70% at about 300 mm.
Becomes almost constant. Further, the pressure loss increases as the width W1 of the concentration separator increases, and rapidly increases when the width exceeds about 300 mm. As a result, when the width W1 of the concentration separator is about 300 mm, the separation efficiency η reaches the target of 70%, and this is a stage before the pressure loss sharply increases. When the width W1 of the density separator is about 300 mm, W1 / W is 300/420 ≒ 0.7.
The density separator 8 set to 0.7 × W has the optimum separation efficiency η, and can suppress the pressure loss to a good value.

As shown in FIG. 2, using the density separator 8
When the separation efficiency η is 70%, the A / C of the air-fuel mixture before separation
Is 2.5 (A = 2.5, C = 1.0), mixing of surrounding parts after separation
A / C of Aiki becomes 4.2 (A = 1.25, C = 0.3) and after separation
A / C of the air-fuel mixture at the center of 1.8 is 1.8 (A = 1.25, C = 0.7)
Becomes Therefore, as described above, good ignition and NO _x
Combustion with a reduced amount of generation is possible.

[0024] By using the shading separator 8 described above, fines can be fed a mixture of air-fuel ratio of the pulverized coal fuel and air different can suppress the NO _x generation amount in one of the rectangular nozzle 6 Can be used as a charcoal burner,
With an easy modification to the existing square nozzles that individually supply air-fuel mixtures having different air-fuel ratios, it is possible to provide a square nozzle 8 that can supply an air-fuel mixture with a dense surrounding area and a thin central area.

[0025]

According to the pulverized coal burner of the present invention, in a pulverized coal burner for feeding an air-fuel mixture of pulverized coal fuel and air to a furnace through a square nozzle, a square concentration separator is provided inside the square nozzle. The concentration separator has a rectangular shape disposed at the center of the square nozzle, and has an inclined portion that gradually expands a cross-sectional shape toward the downstream in the flow direction with the upstream end face in the flow direction of the air-fuel mixture as an apex, A rectangular fluid inlet is formed on the upstream end face in the flow direction of the air-fuel mixture, and a square fluid outlet is formed on the downstream end face in the air-flow direction of the air-fuel mixture. The relationship between the height H1 of the density separator and the height H of the square nozzle is H1 = 0.5 × H, and the width W1 of the density separator and the width of the square nozzle at the downstream end face in the air-fuel mixture flow direction since the relationship between the W and the W1 = 0.7 × W, the NO _x generation amount in one of the rectangular nozzle The pulverized coal burner can supply a mixture of pulverized coal fuel and air having different air-fuel ratios that can be suppressed. As a result, the square nozzle capable of supplying an air-fuel mixture having a dense surrounding area and a thin central area can be easily modified by modifying the existing square nozzle which individually supplies an air-fuel mixture having a different air-fuel ratio. It becomes possible.

According to the method for feeding a gas-fuel mixture in a square nozzle of the present invention, a pulverized coal burner for feeding a mixture of pulverized coal fuel and air to a furnace through a square nozzle has a separation efficiency η of 70% or more. Using a separator, the air-fuel ratio (A / A / F), which is the ratio of the amount of fuel to the amount of air in the mixture supplied to the square nozzle,
Since so as to deliver the mixture to C) as 2.0 to 3.0, it is possible to deliver a mixture so it is possible to suppress the NO _x generation amount in one of the rectangular nozzle. As a result, it is possible to provide a square nozzle capable of easily supplying an air-fuel mixture having a thicker peripheral portion and a thinner central portion to an existing square nozzle which individually supplies air-fuel mixtures having different air-fuel ratios. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a pulverized coal burner according to an embodiment of the present invention.

FIG. 2 is a sectional view of a square nozzle.

FIG. 3 is a view taken along the line III-III in FIG. 2;

FIG. 4 is a view taken along the line IV-IV in FIG. 2;

FIG. 5 is a graph showing the relationship between the width of a density separator, separation efficiency, and pressure loss.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler main body 2 Burner wind box 3 Pulverized coal burner 4 Pulverized coal pipe 5 Kicker block 6 Square nozzle 7 Furnace 8 Gray separator 9 Fixture 10 End face (upstream side) 11 Slope section 12 Fluid inlet section 13 End face (Downstream side) 14 Fluid outlet 15 Flow path

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kotaro Fujimura 5-717-1 Fukahori-cho, Nagasaki-shi, Nagasaki Sanritsu Heavy Industries, Ltd. Nagasaki Research Institute (72) Inventor Kazuhiro Takeuchi No. 1, Akunoura-cho, Nagasaki-shi, Nagasaki No. 1 Inside Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Inventor Hachiro Kawashima 5-717, Fukahori-cho, Nagasaki-shi, Nagasaki F-term in Nagaishi Engineering Co., Ltd.

Claims (5)

[Claims] 1. A pulverized coal burner for feeding an air-fuel mixture of pulverized coal fuel and air to a furnace through a square nozzle, comprising: a square density separator inside the square nozzle; A rectangular shape disposed at the center of the mold nozzle, having an inclined portion that gradually increases in cross-sectional shape toward the downstream in the flow direction with the upstream end surface in the flow direction of the air-fuel mixture as the apex, and an upstream end surface in the flow direction of the air-fuel mixture And a rectangular fluid outlet at the downstream end face in the flow direction of the air-fuel mixture. The fluid inlet and the fluid outlet communicate with each other through a flow path. The relationship between the height H1 and the height H of the square nozzle is H1 =
0.5 × H, and the relationship between the width W1 of the density separator and the width W of the square nozzle at the downstream end face in the flow direction of the mixture is W1 = 0.7.
A pulverized coal burner characterized by XW. 2. The method according to claim 1, wherein the relationship between the height H1 of the gray-scale separator and the height H of the square nozzle is set within a range of ± 15%, and the width W1 of the gray-scale separator and the square nozzle are different. The pulverized coal burner characterized in that the relationship with the width W is set within a range of ± 15%. 3. The relationship between the distance l from the downstream end face of the air-fuel mixture in the flow direction of the air-fuel mixture of the concentration separator to the tip of the square nozzle and the height H of the square nozzle according to claim 1 or 2. /H=1.0 to 2.5. 4. The pulverized coal burner according to claim 3, wherein 1 / H = 1.5. 5. A pulverized coal burner for feeding a mixture of pulverized coal fuel and air to a furnace through a square nozzle.
The air-fuel ratio (A / C), which is the ratio of the fuel amount to the air amount of the air-fuel mixture fed to the square nozzle, is set to 2.0 to 3.0 using a concentration separator η having a separation efficiency η of 2.0% or more. A method for feeding an air-fuel mixture in a square nozzle.