JPH09178116A - Fine powder coal burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a finely powdered coal deposition layer from being formed on a concentration adjusting ring and on an internal cylinder outer peripheral surface. SOLUTION: This finely powdered coal burner is equipped with a burner inner cylinder 1, a burner outer cylinder 3 disposed coaxially with respect to the burner inner cylinder 1, a burner nozzle 4 having a base end mounted on a tip end of the burner outer cylinder 3, a separation cylinder 5 mounted internally coaxially at a predetermined interval with respect to an inner peripheral surface of the burner nozzle 4 and arranged to freely fit to the tip end of the burner inner cylinder 1, and a concentration adjusting ring 24 internally mounted on the burner outer cylinder 3 and externally fitted to a portion located on the side of the base end from the separation cylinder 5 of the burner inner cylinder 1. A cavity 25 extending peripherally of the burner inner cylinder 1 is formed in the concentration adjusting ring 24, and a radial direction deposition preventing air hole 26 is drilled which penetrates from the cavity 25 to the outside of the concentration adjusting ring 24 radially of the burner inner cylinder 1, and further an air supply passage 28 is connected to the cavity 25 from the outside of the burner inner cylinder 1.

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 Conventionally, as one means for burning coal, pulverized coal obtained by pulverizing coal with a mill is mixed with primary air and supplied to a pulverized coal burner, and pulverized coal and primary air ejected from the pulverized coal burner are mixed. Pulverized coal combustion in which a mixed flow is subjected to floating combustion is carried out.

FIG. 4 is a vertical sectional side view showing an example of a pulverized coal burner conventionally used for pulverized coal combustion. This pulverized coal burner comprises a burner inner cylinder 1, an oil burner 2 and a burner outer cylinder 3. , A burner nozzle 4, a separation cylinder 5, and a concentration adjusting ring 6.

The burner inner cylinder 1 is formed in a substantially right-cylindrical shape from the base end portion to the tip end portion, and the inner and outer diameters decrease from the tip end portion to the tip end as the tip end is approached. It is formed in a tapered cylindrical shape.

The oil burner 2 is inserted into the burner inner cylinder 1 so as to be coaxial with the burner inner cylinder 1.

The burner outer cylinder 3 is formed in a straight cylindrical shape from the base end portion to the middle portion, and the inner and outer diameters of the burner outer cylinder 3 decrease from the middle portion to the tip portion as the tip portion approaches. It is formed into a shape.

In the burner outer cylinder 3, the base end portion of the burner outer cylinder 3 is fitted in the burner so that the burner outer cylinder 3 is loosely fitted coaxially with the portion between the base end portion and the vicinity of the tip of the burner inner cylinder 1. It is closely attached to the outer peripheral surface of the base end portion of the cylinder 1.

Further, a pulverized coal inlet 7 is provided at the base end portion of the burner outer cylinder 3, and the pulverized coal inlet 7 is connected to a mill (not shown) to mix the pulverized coal 8 and the primary air 9. A pulverized coal supply pipe 10 for supplying a flow is connected.

The burner nozzle 4 has a burner outer cylinder 3 at the base end.
Is formed to have an inner diameter and an outer diameter that are substantially the same as those of the tip end portion, and is formed in a tapered cylindrical shape in which the inner and outer diameters are reduced as the tip end portion is approached.

The burner nozzle 4 has a base end portion at the tip end portion of the burner outer cylinder 3 which is not shown so that the burner nozzle 4 is coaxially loosely fitted in a portion between the tip end portion of the burner inner cylinder 1 and the tip end. It is attached via fastening means such as bolts.

The separation cylinder 5 has inner and outer diameters decreasing from the base end toward the tip in accordance with the shapes of the vicinity of the tip and the tip of the burner inner cylinder 1, the tip of the burner outer cylinder 3 and the burner nozzle 4. It is formed in a tapered cylindrical shape.

The separating cylinder 5 is loosely fitted coaxially to the burner inner cylinder 1 and is coaxially mounted inside the burner outer cylinder 3 and the burner nozzle 4 at a predetermined distance. The portion is attached to the vicinity of the tip of the inner burner cylinder 1 via a support member such as a bracket (not shown).

The concentration adjusting ring 6 is internally fitted to the burner outer cylinder 3 by being externally fitted to an intermediate portion of the burner inner cylinder 1 closer to the base end than the separating cylinder 5.

The concentration adjusting ring 6 is an annular member, and as shown in FIG. 5, the base end side is formed as a raked rake face 11 whose outer diameter increases toward the middle part, and the middle part is constant. It is formed on a flat rectifying surface 12 having a cylindrical shape with a diameter, and is formed on a diffusing surface 13 whose outer diameter decreases from the intermediate portion toward the tip portion.

The pulverized coal burner shown in FIG.
Of the burner inner cylinder 1, the burner nozzle 4, the separation cylinder 5 and the like, which are arranged so as to penetrate through a wind box 15 provided on the outer side wall of the throat, are opened to the side wall of the furnace 14. It faces the furnace 14 via 16.

From the wind box 15 to the furnace 14
The secondary air 17 for combustion is supplied to the through the throat 16.

In a space formed between the wind box 15 and the throat 16, an air resist 18 for adjusting the swirling force of the secondary air 17 is arranged so as to surround the edge of the throat 16 in the circumferential direction. It is set up.

Also, the wind box 15 and the throat 1
A plurality of inner vanes 19 for separating the secondary air 17 into an inner side and an outer side are arranged in a space formed between the inner resister 6 and the inner side of the air resist 18.

Further, the wind box 15 is connected with a tertiary air pipe 20 which communicates the inside of the wind box 15 with a portion of the internal space of the burner inner cylinder 1 located near the base end. By the tertiary air pipe 20,
The tertiary air 21 is supplied to the inside of the burner inner cylinder 1.

In the pulverized coal burner of FIG. 4 described above, the burner outer cylinder 3 is supplied from the mill (not shown) through the pulverized coal supply pipe 10.
When a mixed flow of pulverized coal 8 and primary air 9 is fed to the flow path between the inner peripheral surface of the burner inner cylinder 1 and the outer peripheral surface of the burner inner cylinder 1, the mixed flow is transferred to the outer peripheral surface of the concentration adjusting ring 6 as shown in FIG. The pulverized coal 8 contained in the mixed flow flowing along the outer peripheral surface of the burner inner cylinder 1 when colliding with the rake face 11 inclined on the base end side of the pulverized coal burner of the concentration adjusting ring 6 shown in FIG. Of the pulverized coal 8 which is guided toward the inner peripheral surface of the burner outer cylinder 3 by the rake face 11, and the pulverized coal 8 which has flowed along the rake face 11 is at the intermediate portion of the outer peripheral surface of the concentration adjusting ring 6. After the flow is adjusted by the flat rectifying surface 12, the flow is diffused by the diffusing surface 13, and the concentration of the mixed flow of the pulverized coal 8 and the primary air 9 is adjusted.

Therefore, the burner outer cylinder 3 and the burner nozzle 4
Through a flow path between the inner peripheral surface of the pulverized coal and the outer peripheral surface of the separation cylinder 5, a mixed flow having a high pulverized coal 8 concentration with respect to the primary air 9 is jetted from the tip of the pulverized coal burner into the interior of the furnace 14. A mixed flow having a low concentration of pulverized coal 8 with respect to the primary air 9 flows from the tip of the pulverized coal burner to the inside of the furnace 14 through the flow path between the inner peripheral surface of the separation cylinder 5 and the outer peripheral surface of the burner inner cylinder 1. Erupted.

The mixed flow of the pulverized coal 8 and the primary air 9 ejected from the tip of the pulverized coal burner into the furnace 14 is
From the wind box 15 through the throat 16 to the furnace 14
A swirling force is applied by the secondary air 17 supplied to the inside of the.

On the other hand, when the oil burner 2 is ignited, a flame is directed from the tip of the pulverized coal burner toward the furnace 14 by the tertiary air 21 supplied from the wind box 15 to the inside of the burner inner cylinder 1 through the tertiary air pipe 20. And the mixed flow of the pulverized coal 8 and the primary air 9 ejected from the tip of the pulverized coal burner into the furnace 14 is ignited, and the pulverized coal 8 flows from the tip of the pulverized coal burner into the furnace 14. A flame is emitted by the combustion of.

[0024]

In the conventional pulverized coal burner described above, due to the particle size of the pulverized coal 8 and the flow velocity of the primary air 9, the flow regulating surface 12 of the concentration adjusting ring 6 shown in FIG.
The pulverized coal 8 is deposited on the surface of the diffusing surface 13 to form a pulverized coal deposit layer 22.
The pulverized coal deposition layer 23 may be formed by depositing the pulverized coal 8 on the portion of the outer peripheral surface located closer to the tip side of the pulverized coal burner than the concentration adjustment ring 6.

When the pulverized coal deposit layers 22 and 23 are formed, the pulverized coal 8 ejected from the tip of the pulverized coal burner.
As a result, it becomes impossible to properly maintain the concentration distribution of the mixed flow of the pulverized coal 8 and the primary air 9, and the pulverized coal deposition layers 22 and 23 are rapidly separated, so that the combustion state of the pulverized coal 8 becomes unstable,
Nitrogen oxide in combustion gas tends to increase.

Further, as the pulverized coal deposition layers 22 and 23 are further grown, the flow passage between the outer peripheral surface of the burner inner cylinder 1 and the inner peripheral surface of the burner outer cylinder 3 of the pulverized coal burner is blocked. Or it may ignite inside the pulverized coal burner.

It is an object of the present invention to provide a pulverized coal burner capable of eliminating such conventional defects and preventing the formation of a pulverized coal deposit layer on the concentration adjusting ring and the outer peripheral surface of the inner cylinder. To do.

[0028]

In order to achieve the above object, in the pulverized coal burner according to claim 1 of the present invention, the burner inner cylinder and the burner inner cylinder are arranged so as to be coaxially fitted therein. A burner outer cylinder, a burner nozzle which is arranged so as to be coaxially loosely fitted to the front end of the burner inner cylinder, and whose base end is attached to the front end of the burner outer cylinder, and an inner circumference of the burner nozzle. A separation cylinder that is coaxially mounted at a predetermined distance from the surface and that is arranged so as to be loosely fitted to the tip of the burner inner cylinder, and a separation of the burner inner cylinder that is mounted in the burner outer cylinder. In a pulverized coal burner equipped with a concentration adjusting ring externally fitted to a portion located closer to the base end than the cylinder, a cavity extending in the circumferential direction of the burner inner cylinder is formed inside the concentration adjusting ring, and To the outside of the concentration adjustment ring Connecting the air supply passage to said cavity radial deposition preventing air holes penetrating bored in the concentration adjusting ring, from the outside of the burner inner cylinder to.

Further, in the pulverized coal burner according to claim 2 of the present invention, in addition to the configuration of the pulverized coal burner according to claim 1 of the present invention described above, the concentration adjustment is performed from a cavity formed inside the concentration adjustment ring. A tip side accumulation preventing air hole penetrating the outside of the ring in the tip direction of the burner inner cylinder is formed in the concentration adjusting ring.

In any of the pulverized coal burners according to claim 1 and claim 2 of the present invention, the air jetted from the radial accumulation preventing air holes of the concentration adjusting ring should be deposited on the flow regulating surface of the concentration adjusting ring. Blow away the pulverized coal.

Further, in the pulverized coal burner according to claim 2 of the present invention, the tip of the pulverized coal burner is blown by the air jetted from the tip side accumulation preventing air holes rather than the concentration adjusting ring on the outer peripheral surface of the burner inner cylinder. Also blow away the pulverized coal that is trying to accumulate in the part located on the side.

[0032]

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

FIGS. 1 to 3 show an example of a mode for carrying out the present invention. The same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

The concentration adjusting ring 24 fitted inside the burner outer cylinder 3 so as to be fitted on the intermediate portion of the burner inner cylinder 1 closer to the base end than the separation cylinder 5 is provided inside the burner inner cylinder 1 in the circumferential direction. An extending cavity 25 is formed, and the outer surface of the concentration adjusting ring 24 is formed on the rake face 11 having a slope whose outer diameter increases toward the middle portion as in the conventional case, and the middle portion is formed. It is formed on a cylindrical flat rectifying surface 12 of a constant diameter,
Diffusion surface 13 whose outer diameter decreases from the middle part to the tip part
Is formed.

The straightening surface 12 in the middle of the density adjusting ring 24
2, a large number of radial accumulation preventing air holes 26 are formed in the burner inner cylinder 1 in the radial direction from the cavity 25 to the outside of the concentration adjusting ring 24, as shown in FIG. .

In addition, on the diffusion surface 13 on the tip end side of the concentration adjusting ring 24, the tip end side deposition prevention that obliquely penetrates in the tip direction of the burner inner cylinder 1 from the cavity 25 to the outside of the concentration adjusting ring 24 is performed. A large number of air holes 27 are provided as shown in FIGS. 1 to 3.

As shown in FIGS. 1 and 3, an air supply passage 28 is provided along the inner surface of the burner inner cylinder 1, and the tip of this air supply passage 28 is a cavity of the concentration adjusting ring 24 described above. 25 is connected.

The base end side (not shown) of the air supply passage 28 is
It is connected to a compressed air source outside the burner inner cylinder 1 so that compressed air is supplied.

The air supply passage 28 is formed by the burner inner cylinder 1
If a plurality of the inner surfaces of the burner inner cylinder 1 are provided at intervals in the circumferential direction, compressed air can be supplied from a plurality of locations to the cavity 25 extending in the circumferential direction of the burner inner cylinder 1.

Next, the operation of the pulverized coal burner shown in FIGS. 1 to 3 will be described.

When a mixed flow of pulverized coal and primary air is fed to the flow path between the inner peripheral surface of the burner outer cylinder 3 and the outer peripheral surface of the burner inner cylinder 1 in the same manner as in the conventional case, air supply is performed. Compressed air is supplied from the base end side of the passage 28.

The compressed air supplied to the air supply passage 28 enters into the cavity 25 of the concentration adjusting ring 24, and then, the radial accumulation preventing air hole 26 and the tip side accumulation preventing air hole 2 are formed.
7 and flows into the interior of the furnace 14 from the tip of the pulverized coal burner together with the mixed flow of the pulverized coal 8 and the primary air 9 (see FIG. 4).

The pulverized coal 8 which is about to be deposited on the surface of the flow regulating surface 12 of the concentration adjusting ring 24 is blown off by the compressed air ejected from the radial accumulation preventing air hole 26, and is ejected from the tip side accumulation preventing air hole 27. Pulverized coal 8 to be deposited on the surface of the diffusion surface 13 of the concentration adjusting ring 24 and on the outer peripheral surface of the burner inner cylinder 1 on the tip side of the pulverized coal burner by the compressed air.
Is blown away, the pulverized coal deposit layer 2
2, 23 (see FIG. 5) are not formed.

The concentration adjusting ring 24 is also cooled by the compressed air ejected from the radial accumulation preventing air holes 26 and the tip side accumulation preventing air holes 27.

The pulverized coal burner of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0046]

INDUSTRIAL APPLICABILITY As described above, the pulverized coal burner of the present invention can exhibit various excellent effects as described below.

(1) In both the pulverized coal burner according to claim 1 and claim 2 of the present invention, the compressed air ejected from the radial accumulation preventing air holes causes the rectifying surface of the concentration adjusting ring to come to the surface. Since the pulverized coal that is about to be deposited is blown away, the pulverized coal deposition layer is not formed, and the combustion state becomes unstable, the pulverized coal burner is clogged, and ignition occurs inside the pulverized coal burner. Can be prevented.

(2) In any of the pulverized coal burners according to the first and second aspects of the present invention, since the concentration adjusting ring is cooled by the compressed air ejected from the radial accumulation preventing air holes, the fine powder is pulverized. The charcoal burner is no longer annealed.

(3) In the pulverized coal burner according to the second aspect of the present invention, compressed air is jetted from the tip side accumulation preventing air holes as well as the radial accumulation preventing air holes.
The pulverized coal that is about to be deposited on the portion located closer to the tip side of the pulverized coal burner than the concentration adjusting ring on the outer peripheral surface of the burner inner cylinder is also blown off, and the pulverized coal deposition prevention effect and the pulverized coal burner cooling effect are further improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an example of an embodiment of a pulverized coal burner of the present invention.

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

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a vertical sectional side view showing an example of a pulverized coal burner which has been conventionally used.

5 is a partially enlarged view of FIG.

[Explanation of symbols]

 1 Burner Inner Cylinder 3 Burner Outer Cylinder 4 Burner Nozzle 5 Separation Cylinder 24 Concentration Adjusting Ring 25 Cavity 26 Radial Deposition Prevention Air Hole 27 Tip Side Deposition Prevention Air Hole 28 Air Supply Passage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirofumi Tsuji 2-6-1 Nagasaka, Yokosuka City, Kanagawa Pref. Central Research Institute of Electric Power Industry Yokosuka Research Center (72) Inventor Yoshihiko Endo 3-2, Toyosu, Koto-ku, Tokyo No. 16 Ishikawajima Harima Heavy Industries Co., Ltd.Toyosu General Office

Claims (2)

[Claims] 1. A burner inner cylinder, a burner outer cylinder arranged to be coaxially fitted to the burner inner cylinder, and a burner inner cylinder to be coaxially fitted to a tip portion of the burner inner cylinder. A burner nozzle whose base end is attached to the tip of the burner outer cylinder, and is coaxially mounted at a predetermined interval with respect to the inner peripheral surface of the burner nozzle, and with respect to the tip of the burner inner cylinder. Pulverized coal provided with a separation cylinder arranged so as to be loosely fitted, and a concentration adjustment ring which is internally fitted to the burner outer cylinder and is externally fitted to a portion of the burner inner cylinder located closer to the base end than the separation cylinder. In the burner, a cavity extending in the circumferential direction of the burner inner cylinder is formed inside the concentration adjusting ring, and a radial accumulation preventing air hole penetrating in the radial direction of the burner inner cylinder from the cavity to the outside of the concentration adjusting ring is formed into the concentration. Drill into the adjustment ring,
A pulverized coal burner characterized in that an air supply passage is connected to the cavity from outside the burner inner cylinder. 2. The concentration adjusting ring is provided with a tip side accumulation preventing air hole penetrating from the cavity formed inside the concentration adjusting ring to the outside of the concentration adjusting ring in the tip direction of the burner inner cylinder. Pulverized coal burner.