JPS63172807A - Method for combustion by pulverized coal burner - Google Patents

Abstract

PURPOSE:To improve the combustion efficiency of a pulverized coal burner, by decreasing the air/pulverized coal ratio on the burner by separating a pri mary air from a pulverized coal in the neighborhood of the inlet of a burner before they are supplied to the pulverized coal burner and by extracting the primary air only which is separated when the air/pulverized coal ratio is high. CONSTITUTION:The pulverized coal prepared by a coal pulverizer is conveyed by a primary air, passing through a pulverized coal pipe 3, and is fed into the outer pipe 1' of a burner 1 after it is swirled in a vent part 6. When a load is applied and the amount of pulverized coal is decreased, the ratio of pulverized coal to a primary air, that is, the air/pulverized coal ratio is in creased. The pulverized coal is swirled and is separated from the primary air by centrifugal force in the bent part 6 of a pulverized coal pipe 3. Accordingly the air/pulverized coal ratio to be supplied to the burner 1 is changed to be decreased by extracting the primary air only from the pulverized coal pipe 3 through the extracting pipe 7 provided in the vent part 6 when the air/ pulverized coal ratio is getting high. With such an arrangement the combustion efficiency of a burner can be improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention reduces the air/pulverized coal ratio in a pulverized coal burner when the ratio of air supplied to the pulverized coal burner and pulverized coal becomes large. The present invention relates to a combustion method for a pulverized coal burner in which combustion is performed to improve combustibility.

[Prior Art] Conventionally, as a pulverized coal burner, as shown in FIG. The pulverized coal pipe 3 is connected tangentially to the other end of the pulverized coal pipe 3 connected to the pulverized coal machine (not shown), and the pulverized coal inside the pulverized coal machine is
Next, the pulverized coal is conveyed through the inside of the pulverized coal pipe 3 by air and enters the above-mentioned outer cylinder 1, where the pulverized coal becomes a swirling flow and is ejected from the tip of the burner. There is a secondary air introduction part 4, and the primary air pulverized coal A is combusted by the secondary air 8 introduced from the secondary air introduction part 4. 5 is a heavy oil burner.

During combustion in the pulverized coal burner with the above configuration, the pulverized coal sent by primary air from the pulverizer is tangentially fed into the outer cylinder 1 of the burner, so the primary air and pulverized coal swirl. while being combusted by secondary air ejected from the tip of the burner and ejected from the secondary air introduction pipe 4,
Good combustion will occur if the ratio of primary air to pulverized coal, ie, the air/pulverized coal ratio, does not change.

[Problems to be Solved by the Invention] However, in a direct combustion system in which pulverized coal is pulverized by a pulverizer and immediately sent to a burner for combustion, the amount of primary air does not change much under partial load. Since the amount of pulverized coal decreases, the air/pulverized coal ratio in the burner section increases, causing a problem in that the concentration of pulverized coal changes and combustibility deteriorates.

Even if an attempt is made to reduce the air/pulverized coal ratio by reducing the primary air amount during partial load in order to improve the above-mentioned combustibility, due to the characteristics of the pulverizer and the prevention of fine powder accumulation in the pulverized coal pipe, Since it is not preferable to reduce the amount of primary air inside the pulverized coal machine or the pulverized coal pipe 3, it is difficult to lower the air/pulverized coal ratio under partial load.

Therefore, the present invention makes it possible to extract a part of the primary air supplied to the burner by the pulverized coal pipe at the burner inlet or by the burner, so that even if the air/pulverized coal ratio becomes large when a load occurs, the air/pulverized coal ratio at the burner can be extracted. The aim is to reduce the pulverized coal ratio and improve combustibility.

[Means for Solving the Problems] In order to achieve the above object, the present invention separates the primary air and the pulverized coal supplied to the pulverized coal burner at a position near the entrance to the burner, and separates the air/pulverized coal. When the coal ratio is high, only the separated primary air is extracted to reduce the air/pulverized coal ratio in the burner.

[Function] When the primary air and pulverized coal supplied to the pulverized coal burner are swirled near the inlet of the burner, the pulverized coal is blown around and separated from the primary air.

If the primary air separated from the pulverized coal can be taken out to the outside, when the air/pulverized coal ratio in the pulverized coal burner increases, if only the primary air is extracted, the pulverized coal can be removed. The air/pulverized coal ratio in the burner can be reduced,
Flammability can be improved.

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

FIG. 1 shows an embodiment of the present invention, in which an outer cylinder 1 and an inner cylinder 2 are arranged in a double layer, and a secondary air introduction part 4 is provided on the outside of the tip side of the outer cylinder 1. Primary air is fed tangentially into the coal burner (1) from a pulverizer (not shown) through the pulverized coal pipe 3, and the coal is rotated between the outer cylinder 1 and the inner cylinder 2 from the tip. In a configuration in which primary air + pulverized coal is blown out, a bend part 6 is provided at a position near the pulverized coal burner inlet of the pulverized coal pipe 3, and an air bleed pipe 7 is connected to the inside of the vent part 6. The primary air and pulverized coal flowing through the pulverized coal pipe 3 are separated by centrifugal force at the bend 6, and
Next, i part of the air is bleeded by the bleed pipe 7.

The air bleed pipe 7 can be connected to the secondary air introduction part 4 of the pulverized coal burner so that the extracted primary air is returned to the burner as secondary air, or it can be connected to a two-stage combustion air port at the top of the burner. so that it is fed into the furnace from

Note that a damper 8 may be provided in the middle of the air bleed pipe 7 in order to adjust the amount of air bleed as necessary.

The pulverized coal produced by the pulverized coal machine is conveyed by primary air, passes through the pulverized coal pipe 3, is rotated at the bend portion 6, and then supplied into the outer cylinder 1 of the burner (2). When a load is generated and the amount of pulverized coal decreases, the ratio of the primary air to pulverized coal, that is, the air/pulverized coal ratio increases. At the bend 6 of the pulverized coal pipe 3, the pulverized coal is blown away by centrifugal force.
When the air/pulverized coal ratio becomes high, only the primary air inside the pulverized coal pipe 3 is extracted from the air bleed pipe 7 of the bend part 6, and the air is supplied to the burner /
Change to reduce pulverized carbonization. This improves combustibility in the burner.

In the present invention, the primary air is extracted near the end of the pulverized coal pipe 3, that is, near the inlet of the pulverized coal burner (2) to reduce the air/pulverized coal ratio. is constant up to the vent part 6, and the air/pulverized coal ratio can be reduced without reducing the transport efficiency of pulverized coal in the pulverized coal machine and the effect of preventing the accumulation of fine powder in the pulverized coal pipe.

In the above embodiment, the primary air is extracted from the air extraction pipe 7 not only when the air/pulverized coal ratio becomes large, but may be extracted all the time. This is because in a pulverized coal burner, there is no problem even if the amount of pulverized coal becomes larger than the amount of primary air. Furthermore, if a deflector 9 is attached to the bend portion 6 of the pulverized coal pipe 3 as shown in FIG. 1 in order to enhance the effect of separating primary air and pulverized coal, the primary air and pulverized coal will be separated by centrifugal force and deflector 9. Deflector 9
By arranging the air bleed pipe 7 on the downstream side of the air bleed pipe 7, only the primary air can be reliably bled.

Next, FIG. 2 shows another embodiment of the present invention, in which a bleed pipe 10 is attached to the pulverized coal inlet of the pulverized coal burner (1). That is, the outer cylinder 1 and the inner cylinder 2 of the pulverized coal burner
The primary air pulverized coal supplied from the pulverized coal pipe 3 between the outer cylinder 1 and the inner cylinder 2 is supplied from the tangential direction so as to form a swirling flow. The pulverized coal is separated by the centrifugal force caused by swirling, with the pulverized coal gathering on the outside and the primary air gathering on the inside. In order to bleed the primary air after separation, an air bleed port 11 is provided on the outside of the inner cylinder 2, and an air bleed pipe 10 is connected to the air bleed port 11.

In the embodiment shown in FIG. 2, the primary air that has entered the burner (2) is extracted, so it is possible to quickly respond to fluctuations in the air/pulverized coal ratio in the pulverized coal burner, and the burner (1)
Air with a high air/pulverized coal ratio can be easily extracted by utilizing the swirling at the pulverized coal, and the bend portion 6 may be omitted. Also, air bleed port 11
If a deflector 12 is attached as shown in the figure, the effect of separating primary air and pulverized coal can be enhanced.

It should be noted that the present invention is not limited only to the above-mentioned embodiments, but has a configuration that uses both the air bleed method shown in FIG. 1 and the air bleed method shown in FIG. The air/pulverized coal ratio may be reduced.

[Effects of the Invention] As described above, according to the pulverized coal burner combustion method of the present invention, pulverized coal is blown to a position near the inlet of the primary air and pulverized coal into the pulverized coal burner by centrifugal force caused by swirling. The device is equipped with a device to bleed only the primary air separated by the pulverized coal burner, and bleeds only the primary air supplied to the pulverized coal burner at a position near the pulverized coal inlet to reduce the air/pulverized coal ratio at the pulverized coal burner. Even if the air/pulverized coal ratio increases due to partial load, the pulverized coal conveyance capacity is not reduced and the amount of pulverized coal is prevented from accumulating in the pulverized coal pipe, while only the primary air amount is maintained. The above air/pulverized coal ratio can be made smaller by reducing
Combustibility in pulverized coal burners can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a pulverized coal burner showing one embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of a pulverized coal burner showing another embodiment of the present invention, and FIG. 3 is a schematic cross-sectional view of a pulverized coal burner showing another embodiment of the present invention. FIG. ■...Pulverized coal burner, 1...Outer cylinder, 2...Inner cylinder,
3...Pulverized coal pipe, 7,10...Air bleed pipe.

Claims (1)

[Claims] 1) A portion is provided near the inlet of the pulverized coal, which is conveyed and supplied to the pulverized coal burner by the primary air, to separate the primary air and the pulverized coal by centrifugal force caused by swirling. At the same time, a device is installed to bleed only the primary air after separation, and when the air/pulverized coal ratio in the pulverized coal burner becomes large, the primary air is extracted with the bleed device to reduce the air/pulverized coal ratio in the burner section. A combustion method using a pulverized coal burner, which is characterized by combustion in a small size.