JPH0798104A - Boiler furnace - Google Patents

Abstract

PURPOSE:To greatly reduce unburned combustibles in ash without increasing the production quantity of NOx for a dust coal burning boiler furnace for a power generating project, etc. CONSTITUTION:AA(Additional air) is used by dividing into 3 stages depending on the purposes. That is, a lower stage AA (7) port is provided at a location which is higher than an uppermost burner by a distance of one stage of the burner, for the purpose of reducing unburned combustibles. An intermediate stage AA (8) is input on the top of the uppermost burner being away from the uppermost burner, in the same manner as a conventional AA input method, for the purpose of reducing NOx, and an NOx reduction area of a sufficient size is formed on the top of a burner part (3). An upper stage AA (9) is input at several locations in the furnace width direction of a de-arch part (2), for the purpose of reducing unburned combustibles (combustion conclusion), and promotes a mixing/diffusion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low NO _x combustion technology in a boiler furnace for power generation business and the like.

[0002]

2. Description of the Related Art FIG. 2 is a schematic view showing an example of a conventional boiler furnace. In the figure, (1) is a boiler furnace body, (2) is a de-arch section, (3) is a burner section, (4) is overfiring air (hereinafter referred to as OFA), and (5) is additional air (hereinafter referred to as AA). And (6) show the gas flow, respectively.

In this boiler furnace, some of the air required to complete the combustion of fuel is OFA (4) and AA (5).
So as to put on the downstream of the burner unit (3) as by reducing the air volume of the burner unit (3) to form _the NO _x reduction zone, it is intended to reduce the NO _x reduction. Although low NO _x reduction is achieved since the burner unit (3) before the AA (5) are squeezed air, air injection of OFA (4) using the burner unit (3) and its integral wind box Speed is 20-3
Since it is as slow as 0 m / s, air diffusion is poor and unburned content increases rapidly. Further, even in the combustion region after AA (5), the AA flow rate is about 60 m / s, but it is still insufficient, and it is difficult to uniformly diffuse air in the cross section of the furnace.

[0004]

In the conventional low NO _x combustion method by introducing AA, there are the following problems to be solved. 1) If the AA input amount is increased at the time of adjustment, the secondary air flow rate of the main burner portion, and consequently the flow velocity, will decrease, so that the diffusion temperature will reach the low temperature AA jetting area without diffusion. Then, the unburned amount increases rapidly.

2) AA to form the NO _x reduction zone
Since the port is installed in the upper part of the furnace, which is slightly away from the burner part, it is necessary to use the AA
The air is difficult to diffuse and the combustion condition after AA is not good.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention is directed to a power generation device having a vertical rectangular tubular shape, a de-arch portion in the upper portion, and a plurality of burners in the lower portion. In the boiler furnace, a lower stage AA charging nozzle disposed in proximity to the uppermost burner among the plurality of stages of burners, and a plurality of upper stage AA charging nozzles disposed in the de-arch portion along the furnace width direction. And the middle AA arranged at a height approximately midway between the upper AA charging nozzle and the lower AA charging nozzle.
The present invention proposes a boiler furnace characterized by having a charging nozzle.

[0007]

In the present invention, by injecting air at a high speed from the lower AA charging nozzle that is disposed close to and above the uppermost burner, the air passes through the NO _x reduction region of the burner section and becomes unburned fuel. Improves mixing and diffusion with air. In the burner section, the amount of air is further reduced and stronger N than before.
_Ox reduction zones can be formed.

Next, since the middle AA charging nozzle is installed at a relatively distant position from the burner as in the case of the conventional AA charging nozzle, a sufficiently large NO _x reduction zone is formed from the burner to the upper side. , NO _x is reduced.

Further, since the upper AA charging nozzle is installed in the de-arch portion of the furnace where the cross-sectional area is small, it is possible to perform better mixing / diffusion by blowing out the air from here at a high speed. By arranging a plurality of these nozzles along the furnace width direction, the drift of the combustion gas from the de-arch portion can be further increased, and the furnace space at the top of the furnace can be effectively utilized.

[0010]

1 is a schematic view showing an embodiment of the present invention. FIG. 1 (a) is a vertical side view and FIG. 1 (b) is FIG. 1 (a).
It is a BB horizontal sectional view. In the figure, (1) is a vertical rectangular tube-shaped boiler furnace body having a de-arch section (2) at the top,
(3) is a burner portion which is provided in the lower part of the boiler furnace body (1) and is composed of a plurality of stages of burners. (7) is a lower stage AA, which is introduced from a nozzle arranged close to (above about one stage of the burner) above the uppermost burner of the plurality of stages of burners, and (9) is the de-arch section. Upper stage A that is charged from a plurality of nozzles arranged in (2) along the furnace width direction
A and (8) are middle stages AA which are thrown from nozzles arranged at a height approximately midway between the throwing nozzles of the upper stage AA (9) and the lower stage AA (7). Moreover, (6) shows a gas flow.

The lower stage AA (7) maintains the jet flow velocity at 60 m / s or more, and the AA amount is about 0.3 in terms of air ratio.
As a result, mixing and diffusion of unburned fuel, such as unburned pulverized coal particles (char), and air that have passed through the NO _x reduction region of the burner section (3) is improved, and these unburned components are burned. . Further, in the burner section (3), the amount of air can be further reduced to form a strong NO _x reduction region as compared with the conventional case. The lower AA (7) charging position is almost the same as that of the conventional OFA (reference numeral (4) in FIG. 2) charging device. However, since the conventional OFA (4) used the same wind box as the burner,
While it was not possible to increase the jet flow velocity, in this embodiment, the flow velocity can be freely selected because it is input as AA (7) independent of the burner wind box,
It is maintained at 0 m / s or more.

Next, the middle AA (8) plays the same role as the conventional AA (reference numeral (5) in FIG. 2). That is, since it is introduced at a position slightly away from the burner section (3), a sufficient amount of NO is provided from the burner section (3) to above it.
_{An x} reduction zone is formed and NO _x is reduced. This middle stage A
The jet flow velocity of A (8) is also maintained at 60 m / s or more, and the AA amount is about 0.3 in terms of air ratio. In addition, in FIG.
Although only one stage of A (8) is shown, the number of stages may be two or more.

Finally, the upper stage AA (9) is installed in the de-arch section (2) of the furnace where the cross-sectional area is small.
At a flow velocity of 0 m / s, the mixing and diffusion of air becomes even better.
As a result, the unburned content is further reduced. The AA amount may be about 0.1 in terms of air ratio. Further, by blowing out from several places along the furnace width direction, the drift of the combustion gas from the de-arch part (2) is further increased, and the furnace space at the top of the furnace body (1) is effectively utilized.

In summary, in the conventional AA charging system, the air in the burner section is squeezed to make the burner section air-deficient and the generated NO _x is reduced to N ₂ . However, this method causes an increase in unburned components. Also in the present invention, the middle stage AA (8) is intended to reduce NO _x , while the upper stage AA (9) and the lower stage AA (7) are mainly intended to reduce unburned components. That is, since the air diffusion is basically good in the burner section (3), the air is sufficiently squeezed to NO _x.
To reduce. Next, the unburned part of the burner part (3) is rapidly burned by the high speed jet of 60 m / s in the lower stage AA (7) immediately above. At this time, NO _x increases, but this is
Reduce by (8). After that, the unburned component is further reduced by charging the upper stage AA (9) from the de-arch portion (2). In this case, the gas temperature is sufficiently low that N
It has been confirmed by the results of simulation analysis that the amount of unburned oxygen is reduced although the amount of O _x is not generated so much.

[0015] Figure 3 is illustrative of the large combustion test furnace results of tests carried out using in order to confirm the effects of the present invention, the amount of NO _x and ash unburned to the total AA content, conventional It is shown in comparison with the case of a boiler furnace. It can be seen from this figure that the unburned content in the ash is significantly reduced in the present invention as compared with the prior art.

[0016]

According to the present invention, in the boiler furnace for power generation, the unburned content in the ash can be significantly reduced as compared with the conventional one, without increasing the NO _x generation amount.

[Brief description of drawings]

1 is a schematic view showing an embodiment of the present invention, FIG. 1 (a) is a vertical side view, and FIG. 1 (b) is FIG. 1 (a).
It is a BB horizontal sectional view.

FIG. 2 is a schematic diagram showing an example of a conventional boiler furnace.

FIG. 3 is a diagram illustrating the result of a test for confirming the effect of the present invention.

[Explanation of symbols]

 (1) Boiler furnace body (2) De-arch section (3) Burner section (4) Over-firing air (OFA) (5) Additional air (AA) (6) Gas flow (7) Lower stage AA (8) Middle stage AA (9) Upper AA

Claims (1)

[Claims] 1. A boiler furnace for power generation, which has a vertical rectangular tube shape, has a de-arch section in an upper portion, and has a plurality of burners in a lower portion, and has a plurality of burners above the uppermost burner. The lower additional air charging nozzles arranged in close proximity, the upper additional air charging nozzles arranged in the de-arch section along the furnace width direction, the upper additional air charging nozzle and the lower additional air charging nozzle A boiler furnace equipped with a middle-stage additional air injection nozzle arranged at approximately the middle height.