JP2002106811A - Pulverized coal burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulverized coat burner, in which the grain size and concentration of pulverized coal can be uniformed, the efficiency of mixing the pulverized coal and combustion air can be improved, and NOx can be reduced. SOLUTION: A hollow disc-type distributor 23, in the center of which partition plates 22 are placed extending radially, is provided with the axial line nearly horizontally extended. A pipe 7 for feeding pulverized coal is connected at the center on the base-end face of the distributor 23. The pulverized coal 21 is distributed in each space 24 partitioned with plates 22 of the distributor 23. A plurality of pulverized coal tubes 25 are provided at the tip-end surface of the distributor 23, nearly horizontally extending peripherally around the axial line at necessary intervals, to be connected to respective spaces 24. A nozzle 26 is bend-formed at the tip end of the tubes 25, to inject the pulverized coal 21 with the axial line of the distributor 23 as its center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a pulverized coal burner.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a mill and a pulverized coal burner in a general coal-fired boiler.
Among them, 1 is a coal-fired boiler main body, 2 is a furnace of the boiler main body 1, 3 is a pulverized coal burner for injecting and burning pulverized coal into the boiler main body 1, and 4 is pulverized coal to pulverized coal. , A primary air supply pipe for supplying primary air 9 to the mill 4, a primary air shut damper 6 provided in the primary air supply pipe 5, and a pulverized coal pulverized by the mill 4. A pulverized coal supply pipe 8 for leading to the pulverized coal burner 3 is a cut damper provided in the pulverized coal supply pipe 7.

A plurality of pulverized coal supply pipes 7 (six, A, B, C, D, E, F in the example of FIG. 4) are provided in one mill 4, and each pulverized coal burner 3 When the mill 4 is operated, the primary air shut damper 6 is opened, the primary air 9 is introduced into the mill 4 from the primary air supply pipe 5, and the desired cut damper 8 is opened. Into a mill 4 by a coal feeder (not shown).
And pulverized pulverized coal into primary air 9
As a result, air is conveyed to the pulverized coal burner 3 via the pulverized coal supply pipe 7 and burned in the furnace 2 of the boiler main body 1.

As shown in FIG. 5, the pulverized coal burner 3 has a burner outer cylinder 10 and a burner inner cylinder 11 arranged concentrically. The pulverized coal introduction port 12 is protruded so as to extend in the tangential direction, and the pulverized coal introduction port 12 is connected to the pulverized coal supply pipe 7 extending from the mill 4 (see FIG. 4). The tip of the burner outer cylinder 10 is opened to the throat portion 13 through a wind box 14 provided so as to cover the throat portion 13 formed on the side wall of the furnace 2.

[0005] The throat section 13 and the wind box 1
In the space formed between the wind box 14 and the
The air register 16 for adjusting the swirling force of the secondary air 15 for combustion supplied to the furnace 2 from the throat 13
, A plurality of inner vanes 17 for separating the secondary air 15 into the inside and the outside are arranged inside the air register 16 in the circumferential direction. And the base end of the burner inner cylinder 11 are communicated by a tertiary air pipe 18 so that tertiary air 19
To the burner inner cylinder 11.

An oil burner 20 is removably inserted into the shaft center of the burner inner cylinder 11.

In the pulverized coal burner 3 shown in FIG. 5, pulverized coal 21 pulverized by the mill 4 (see FIG. 4) is supplied to the burner outer cylinder 10 through the pulverized coal supply pipe 7 and the pulverized coal inlet 12.
Is supplied together with the primary air 9 to the inside of the burner outer cylinder 10.
At the base end of the burner outer cylinder 10
While flowing in the circumferential direction in the space between the inner cylinder 11 and the burner, it flows toward the distal end side, squirts from the opening of the distal end of the burner outer cylinder 10 to the throat portion 13, and the air register 16 and the inner vane 17 from the wind box 14. And the tertiary air 19 supplied from the tip of the burner inner cylinder 11 to be burned in the furnace 2.

[0008]

However, in the conventional pulverized coal burner 3 as described above, the coarse and fine particles are separated by the centrifugal force of the pulverized coal 21 at the base end entrance of the outer cylinder 10 of the burner. Coarse grains increase on the outer peripheral side of the distal end of the outer cylinder 10 and finer particles increase on the inner peripheral side, causing unevenness in the particle size of the pulverized coal 21 at the distal end of the burner outer cylinder 10. When the pulverized coal 21 is conveyed by the primary air 9 from the base end inlet portion of the cylinder 10 to the tip ejection portion, due to the effect of gravity, the upper portion of the tip ejection portion of the burner outer cylinder 10 becomes closer to the top portion of the pulverized coal 21.
The concentration of pulverized coal 21 is lower at the lower part,
Non-uniformity of the concentration of the pulverized coal 21 occurs at the tip ejection portion of the burner outer cylinder 10. The mixing efficiency has decreased, the unburned content has increased, and this has been a barrier to NOx reduction.

In view of such circumstances, the present invention can make the particle size and concentration of pulverized coal at the tip ejection section uniform, improve the mixing efficiency between pulverized coal and combustion air, and reduce unburned fuel. An object of the present invention is to provide a pulverized coal burner that can be reduced and leads to a reduction in NOx.

[0010]

According to the present invention, a pulverized coal supply pipe is connected to a central portion on the base end surface side of a hollow disk and extends in a substantially horizontal direction, and is internally radiated from the central portion. A plurality of extending partition plates are provided, and a pulverized coal is distributed and supplied to each space partitioned by the partition plates, and a required interval in the circumferential direction around an axis of the distributor at a tip end surface side of the distributor. A plurality of pulverized coal pipes which are arranged side by side so as to extend in a substantially horizontal direction and are connected to the respective spaces; and a pulverized coal formed at the tip of each of the pulverized coal pipes, and the pulverized coal is formed around the axis of the distributor. A pulverized coal burner, comprising: a nozzle section that jets out a swirling flow.

According to the above means, the following effects can be obtained.

In the pulverized coal burner of the present invention, the pulverized coal pulverized by the mill is supplied together with the primary air to the inside of the distributor through the pulverized coal supply pipe, and collides with the opposing wall in the distributor. Pulverized coal dispersed radially along a plurality of partition plates, distributed and supplied to each space, and the pulverized coal distributed and supplied to each space respectively flows inside the pulverized coal pipe, from a nozzle formed at the tip end thereof. The fuel is ejected as a swirling flow about the axis of the distributor and mixed with combustion air to perform combustion.

Here, in the case of the pulverized coal burner of the present invention, when the pulverized coal is radially dispersed along a plurality of partition plates, coarse particles and fine particles are not separated by centrifugal force of the pulverized coal, and Non-uniformity in the particle size of the pulverized coal is less likely to occur at the tip of the burner.

On the other hand, when the pulverized coal is radially dispersed along the plurality of partition plates, the concentration of the pulverized coal in the space located at the lower part of the distributor becomes slightly higher due to the influence of gravity, and accordingly, Although the concentration of pulverized coal in the pulverized coal pipe located at the location slightly increases, the pulverized coal ejected from each pulverized coal pipe is given a strong swirl by the curved nozzle part,
In the pulverized coal burner, the non-uniformity of the concentration is less likely to occur at the tip ejection portion.

As a result, as compared with the conventional pulverized coal burner, the non-uniformity of the particle size and concentration of the pulverized coal is improved, the mixing efficiency with the combustion air is improved, the unburned content is not increased, and the low NOx is reduced. Can be realized.

[0016]

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

FIGS. 1 to 3 show an embodiment of the present invention. In the figures, the parts denoted by the same reference numerals as those in FIGS. A distributor 23 in which a plurality of partition plates 22 extending radially from a central portion are disposed is disposed such that the axis thereof extends in a substantially horizontal direction, and a pulverized coal supply pipe is provided at a central portion on the base end surface side of the distributor 23. 7
So that the pulverized coal 21 is distributed and supplied to each space 24 partitioned by the partition plate 22 of the distributor 23, and is required on the distal end surface side of the distributor 23 in the circumferential direction around its axis. Each of the spaces 2 extends in a substantially horizontal direction at an interval.
A plurality of pulverized coal pipes 25 are arranged side by side so as to be connected to the pulverized coal pipe 4, and a nozzle section 26 for ejecting pulverized coal 21 as a swirling flow around the axis of the distributor 23 at the tip of each of the pulverized coal pipes 25. To form a pulverized coal burner 3.

Next, the operation of the illustrated example will be described.

In the pulverized coal burner 3 shown in FIGS. 1 to 3, the pulverized coal 21 pulverized by the mill 4 (see FIG. 4) is supplied to the inside of the distributor 23 through the pulverized coal supply pipe 7 with the primary air 9. The pulverized coal 21 which is supplied together, collides with the opposing wall inside the distributor 23, is radially dispersed along the plurality of partition plates 22, is distributed and supplied to each space 24, and is distributed and supplied to each space 24 is Each flows through the inside of the pulverized coal pipe 25, and is ejected from the nozzle portion 26 formed at the tip portion thereof to the throat portion 13 as a swirling flow about the axis of the distributor 23,
The air is mixed with the secondary air 15 supplied from the wind box 14 through the air register 16 and the inner vane 17 and the tertiary air 19 supplied from the tip of the burner inner cylinder 11, and is burned in the furnace 2.

Here, the pulverized coal burner 3 shown in FIGS.
In the case of pulverized coal, when the pulverized coal 21 is dispersed radially along the plurality of partition plates 22, the separation of the coarse particles and the fine particles due to the centrifugal force of the pulverized coal 21 does not occur, and the pulverized coal is Non-uniformity of the particle size of 21 is less likely to occur.

On the other hand, when the pulverized coal 21 is radially dispersed along the plurality of partition plates 22, the distribution
The concentration of the pulverized coal 21 in the space 24 located at the lower part of the pulverized coal is slightly increased.
Although the concentration of pulverized coal 21 in the inside slightly increases, each pulverized coal pipe 2
Since the pulverized coal 21 ejected from the pulverized coal 5 to the throat portion 13 is strongly swirled by the curved nozzle portion 26, non-uniform density is hardly generated at the tip ejection portion of the pulverized coal burner 3.

As a result, as compared with the conventional pulverized coal burner 3 as shown in FIG. 5, the particle size and concentration of the pulverized coal 21 are improved, and the secondary air 15 and the tertiary air 19 are improved.
As a result, the mixing efficiency with the combustion air is improved, the unburned portion does not increase, and the NOx can be reduced.

In this manner, the pulverized coal 21
Particle size and concentration of pulverized coal 21
The efficiency of mixing the fuel with the combustion air can be improved, the unburned content can be reduced, and the NOx can be reduced.

It should be noted that the pulverized coal burner of the present invention is not limited to the illustrated example described above, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

[0025]

As described above, according to the pulverized coal burner of the present invention, the particle size and concentration of the pulverized coal at the tip ejection section can be made uniform, and the mixing efficiency between the pulverized coal and the combustion air can be improved. It is possible to improve the effect, reduce the unburned matter, and achieve an excellent effect of reducing NOx.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an example of an embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrows II-II in FIG.

FIG. 3 is a view taken in the direction of arrows III-III in FIG. 1;

FIG. 4 is a schematic configuration diagram illustrating an example of a mill and a pulverized coal burner in a coal-fired boiler.

FIG. 5 is a side sectional view showing an example of a conventional pulverized coal burner.

[Explanation of symbols]

 3 Pulverized coal burner 7 Pulverized coal supply pipe 21 Pulverized coal 22 Partition plate 23 Distributor 24 Space 25 Pulverized coal pipe 26 Nozzle part

Claims (1)

[Claims] 1. A hollow disk-shaped arrangement in which an axis extends in a substantially horizontal direction, a pulverized coal supply pipe is connected to a central portion on a base end surface side, and a plurality of partition plates extending radially from the central portion are disposed inside. And a distributor in which pulverized coal is distributed and supplied to each of the spaces partitioned by the partition plate, and extends in a substantially horizontal direction on a distal end surface side of the distributor with a required interval in a circumferential direction around an axis thereof. A plurality of pulverized coal pipes which are juxtaposed and connected to each of the spaces; and a nozzle section which is formed at the tip of each of the pulverized coal pipes and which ejects the pulverized coal as a swirling flow about the axis of the distributor. And a pulverized coal burner.