JP2698464B2 - Pulverized coal burner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pulverized coal burner used in a furnace of a pulverized coal-fired boiler, and more particularly to a stable pulverized coal burner capable of performing stable combustion when the load of a mill is reduced. It relates to burned pulverized coal burners.

[Prior art] Pulverized coal pulverized by a mill is conveyed by primary air and burned by a pulverized coal burner. However, when the load of the mill decreases and the amount of pulverized coal conveyed from the mill decreases, the primary air becomes Since the flow rate cannot be reduced below a certain value to secure the pulverized coal transfer power, the concentration of pulverized coal supplied to the pulverized coal burner in the primary air decreases, and the pulverized coal burner is stable. Combustion cannot be obtained.

For this reason, conventionally, when the load of the mill is low, the low-concentration pulverized coal conveyed by the primary air from the mill is guided to an external cyclone, and the pulverized coal is highly concentrated by centrifugal force in the cyclone before being supplied to the pulverized coal burner. Thus, stable combustion of the pulverized coal burner was obtained.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional pulverized coal burner, a cyclone is used to increase the concentration of pulverized coal when the load of the mill is low, so that the configuration of the apparatus becomes complicated,
There was a problem that maintenance became difficult.

The present invention has been made in view of the above circumstances, and has as its object to provide a pulverized coal burner capable of increasing the concentration of pulverized coal without using a cyclone and obtaining stable combustion even when the load of the mill is low.

Means for Solving the Problems The present invention provides a substantially cylindrical tertiary air nozzle, a pulverized coal nozzle concentrically disposed on the outer periphery of the tertiary air nozzle, and a tangential direction at a rear end of the pulverized coal nozzle. A pulverized coal supply port formed toward the pulverized coal nozzle, a rectilinear guide extending in the front-rear direction attached to the inner surface of the pulverized coal nozzle, and slidably provided in the pulverized coal nozzle in the front-rear direction along the outer periphery of the tertiary air nozzle. A pulverized coal burner and a substantially cylindrical tertiary air nozzle; a pulverized coal nozzle disposed concentrically around the outer periphery of the tertiary air nozzle; A pulverized coal supply port formed in the rear end of the nozzle in a tangential direction, a rectilinear guide extending in the front-rear direction attached to the inner surface of the pulverized coal nozzle tip, and a pulverized coal nozzle disposed at the pulverized coal nozzle tip The inside of the tip is an inner passage A separation cylinder that separates into an outer passage, and a concentration adjusting ring that is provided at the rear end side of the pulverized coal nozzle at a rear end side of the separation cylinder along the outer periphery of the tertiary air nozzle so as to be slidable in the front-rear direction within the pulverized coal nozzle. A pulverized coal burner characterized by comprising:

[Operation] In the first invention, when the load of the mill is high, the concentration adjusting ring is moved to the rear end side of the pulverized coal nozzle.

Then, the distance between the tip of the pulverized coal nozzle and the concentration adjusting ring increases, so that the pulverized coal and the primary air supplied to the pulverized coal nozzle are squeezed through the portion of the concentration adjusting ring and then spread again. The pulverized coal is uniformly dispersed in the primary air and is ejected from the tip of the pulverized coal nozzle.

When the load of the mill is low, the concentration adjusting ring is moved toward the tip of the pulverized coal nozzle.

Then, the distance between the tip of the pulverized coal nozzle and the concentration adjusting ring becomes smaller, so that the pulverized coal and the primary air are drawn toward the outer periphery of the pulverized coal nozzle at the portion of the concentration adjusting ring, and then the primary air that has passed through the concentration adjusting ring. The air spreads again throughout the pulverized coal nozzle, and the pulverized coal having a specific gravity sufficiently higher than that of the primary air is separated from the airflow by inertia, flows as it is on the outer periphery of the pulverized coal nozzle, and is ejected from the tip of the pulverized coal nozzle.

Therefore, the pulverized coal is partially concentrated in the primary air and is ejected from the pulverized coal nozzle tip, so that the combustion of the pulverized coal burner is stabilized when the load of the mill is low.

In the second invention, since the straight guide is provided only at the tip of the pulverized coal nozzle, the pulverized coal and the primary air supplied from the pulverized coal nozzle rear end are directed toward the tip while turning the pulverized coal nozzle rear end. Due to the centrifugal force generated by the flow swirl, pulverized coal whose specific gravity is sufficiently higher than that of the primary air is collected on the outer peripheral side of the pulverized coal nozzle, so that the pulverized coal is partially concentrated in the primary air for transportation. Become.

Therefore, when the mill is under a high load, if the concentration adjusting ring is moved to a predetermined position on the rear end side, the separation of the pulverized coal due to the swirling of the primary air at the concentration adjusting ring portion is hindered at an early stage, so that pulverized coal is sufficient. And the pulverized coal is again dispersed in the primary air downstream of the concentration adjusting ring, so that the primary air and the pulverized coal are ejected together from both the outer passage and the inner passage.

When the mill is under a low load, moving the ring for concentration adjustment to the tip side increases the distance between the pulverized coal supply port and the ring for concentration adjustment, so the pulverized coal is sufficiently brought to the outer periphery of the pulverized coal nozzle by centrifugal force. The collected pulverized coal and the primary air are partially concentrated in the primary air, and the pulverized coal and the primary air are separately ejected from the pulverized coal nozzle through the outer passage and the inner passage, respectively.

Therefore, the combustion of the pulverized coal burner is stabilized when the load of the mill is low.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

 1 to 5 show an embodiment of the present invention.

In the drawing, 1 is a pulverized coal burner, 2 is a substantially cylindrical tertiary air nozzle disposed at the center of the pulverized coal burner 1, 3 is disposed concentrically on the outer periphery of the tertiary air nozzle 2 and goes to the tip Pulverized coal nozzle having a substantially hollow cone shape whose diameter decreases according to
Reference numeral denotes an oil burner disposed at the axial center of the tertiary air nozzle 2, and reference numerals 2 'and 3' denote throttle portions formed at the tip openings of the tertiary air nozzle 2 and the pulverized coal nozzle 3, respectively.

Reference numeral 6 denotes a pulverized coal supply port formed at the rear end of the pulverized coal nozzle 3 in a tangential direction and supplies pulverized coal 7 from a mill (not shown) to the pulverized coal nozzle 3 together with primary air. A rectilinear guide extending in the front-rear direction attached to a plurality of locations in the circumferential direction with respect to a portion ahead of the pulverized coal supply port 6 forming portion, and 9 is slidable in the front-rear direction inside the pulverized coal nozzle 3 along the outer periphery of the tertiary air nozzle 2. A density adjusting ring having a tapered surface 9 'having a tapered surface 9' whose diameter increases toward the front end at the rear end surface, and a tapered surface 9 "having a slope substantially equal to that of the throttle portion 2 'at the front end surface. Is a rod extending in the front-rear direction, which is connected to a concentration adjusting ring 9, passes through the pulverized coal nozzle 3 via a seal 11, is drawn out to the outside, and has a cylinder 12 connected to the other end.

Reference numeral 13 denotes a throat formed in the furnace 14 of the boiler, 15 denotes a wind box for supplying secondary air 16 for combustion to the furnace 14 via the throat 13, and 17 denotes a wind box formed between the throat 13 and the wind box 15. An air register for adjusting the air amount of the secondary air 16 disposed so as to surround the throat 13 in a circle in the space provided, and 18 is a secondary air disposed circularly inside the air register 17. A plurality of inner vanes for giving a turning force to 16, 19 is a flow path connecting the wind box 15 and the rear end of the tertiary air nozzle 2 via a damper 20, and the pulverized coal burner 1 penetrates the wind box 15. It is arranged at the center of the throat 13.

 Next, the operation will be described.

At the time of high load of a mill (not shown), the density adjusting ring 9 is moved to the rear end side through the rod 10 using the cylinder 12 as shown in FIG.

In this state, the pulverized coal 7 pulverized by a mill (not shown) is conveyed by primary air and supplied to the pulverized coal supply port 6 of the pulverized coal nozzle 3.

Then, first, the pulverized coal supply port 6 is formed in the tangential direction of the pulverized coal nozzle 3, so that the pulverized coal 7 and the primary air supplied from the pulverized coal nozzle 3 orbit around the rear end of the pulverized coal nozzle 3. After being equalized in the direction, it flows toward the tip of the pulverized coal nozzle 3, and is moved in the radial direction while being prevented from moving in the circumferential direction by the rectilinear guide 8 extending in the front-rear direction provided on the inner peripheral surface of the pulverized coal nozzle 3. It is equalized and goes straight ahead.

On the way, the pulverized coal 7 and the primary air pass through the portion of the concentration adjusting ring 9 inside the pulverized coal nozzle 3 and are brought to the outer peripheral side of the pulverized coal nozzle 3. , The distance a between the inner surface of the conical pulverized coal nozzle 3 and the concentration adjusting ring 9 is kept relatively wide, and the distance l between the tip of the pulverized coal nozzle 3 and the concentration adjusting ring 9 is l. Is kept large, so that the pulverized coal 7 and the primary air pass through the concentration adjusting ring and then spread again over the entire pulverized coal nozzle 3 so that the pulverized coal 7 and the primary air are contained in the primary air.
Are spouted from the tip of the pulverized coal nozzle 3 in a state of being uniformly dispersed.

The pulverized coal 7 ejected from the pulverized coal nozzle 3 is mainly mixed with the secondary air 16 from the wind box 15 and burned.

When the load of the mill (not shown) is low, the density adjusting ring 9 is moved to the distal end side through the rod 10 using the cylinder 12 as shown in FIG.

In this state, the pulverized coal 7 pulverized by a mill (not shown) is conveyed by primary air and supplied to the pulverized coal supply port 6 of the pulverized coal nozzle 3.

Then, since the pulverized coal supply port 6 is formed in the tangential direction of the pulverized coal nozzle 3, the pulverized coal 7 and the primary air supplied from the pulverized coal nozzle 3 orbit around the rear end of the pulverized coal nozzle 3 and extend in the circumferential direction. After being equalized, it flows toward the tip of the pulverized coal nozzle 3 and is equalized in the radial direction while being prevented from moving in the circumferential direction by the rectilinear guide 8 extending in the front-rear direction provided on the inner peripheral surface of the pulverized coal nozzle 3. Go straight ahead.

On the way, it passes through the part of the concentration adjusting ring 9 inside the pulverized coal nozzle 3.

Then, the pulverized coal 7 and the primary air are guided by the tapered surface 9 ′, whose diameter increases toward the tip formed on the rear end face of the concentration adjusting ring 9, at the concentration adjusting ring 9, The nozzle 3 is offset toward the outer peripheral side.

At this time, since the concentration adjusting ring 9 is located at the tip end side of the pulverized coal nozzle 3, the conical pulverized coal nozzle 3
Since the distance a between the inner surface and the concentration adjusting ring 9 is reduced and the distance l between the tip of the pulverized coal nozzle 3 and the concentration adjusting ring 9 is reduced, the flow velocity of the pulverized coal 7 and the primary air is increased, Immediately after passing through the concentration adjusting ring 9, the primary air spreads again to the entire pulverized coal nozzle, and the pulverized coal 7 having a specific gravity sufficiently larger than the primary air is applied to the outer peripheral side of the pulverized coal nozzle 3 by inertia as it is. Before flowing and spreading, it is ejected from the tip of the pulverized coal nozzle 3.

Therefore, the pulverized coal 7 ejected from the pulverized coal nozzle 3 is ejected in a partially concentrated state in the primary air, and the combustion of the pulverized coal burner 1 is stabilized.

The highly concentrated pulverized coal 7 ejected from the pulverized coal nozzle 3 is mainly mixed with the secondary air 16 from the wind box 15 and burned.

6 and 7 show another embodiment of the present invention, in which a movable vane 5 for adjusting the opening degree is attached to the pulverized coal supply port 6 and a straight guide 21 is attached only to the tip side of the pulverized coal nozzle 3. The rear end side of the pulverized coal nozzle 3 is defined as a revolving separation area 22 without the rectilinear guide 21, and the rectilinear guide at the tip of the pulverized coal nozzle 3.
A configuration substantially the same as that of the above-described embodiment except that a separation cylinder 25 having a straight guide 26 is disposed inside a portion provided with 21 and separates the inside of the tip of the pulverized coal nozzle 3 into an inner passage 23 and an outer passage 24. It has.

In this embodiment, the pulverized coal 7 supplied to the pulverized coal supply port 6
And the primary air swirls inside the swirl separation zone 22 formed at the rear end of the pulverized coal nozzle 3, and the pulverized coal 7 having a higher specific gravity than the primary air due to the centrifugal force generated by the swirl moves to the outer peripheral side of the pulverized coal nozzle 3. , Light primary air is separated to the inner peripheral side of the pulverized coal nozzle 3 and the pulverized coal 7 on the outer peripheral side at the tip of the pulverized coal nozzle 3.
Pass through the outer passage 24 formed on the outer periphery, and the primary air on the inner periphery tries to pass through the inner passage 23 formed on the inner periphery.

Therefore, when the mill is under a high load, the density adjusting ring 9 is moved to a predetermined position on the rear end side using the cylinder 12.

Then, in the portion of the concentration adjusting ring 9, the separation of the pulverized coal 7 due to the swirling of the primary air is hindered at an early stage, so that the pulverized coal 7 is not sufficiently separated. The pulverized coal 7 is dispersed in the air, and the pulverized coal 7 and the primary air come together to form the inner passage 23.
The pulverized coal nozzle 3 is ejected from both ends of the pulverized coal nozzle 3 through the outer passage 24 and the outer passage 24.

When the load of the mill is low, the density adjusting ring 9 is moved to the tip side using the cylinder 12.

Then, the distance between the pulverized coal supply port 6 and the concentration adjusting ring 9 increases, so that the pulverized coal 7 is sufficiently gathered to the outer peripheral side of the pulverized coal nozzle 3 by centrifugal force and partially separated from the primary air. Since the pulverized coal 7 is in a highly concentrated state, the pulverized coal 7 passes through the outer passage 24 and the primary air passes through the inner passage 23 and is ejected from the tip of the pulverized coal nozzle 3.

Therefore, the combustion of the pulverized coal burner 1 is stabilized when the load of the mill is low.

In the above embodiment, the concentration of the pulverized coal is adjusted using the ring 9 for concentration adjustment, but the adjustment is performed by the movable vane 5 disposed in the pulverized coal supply port 6 as shown in FIG. Is also possible.

As described above, the pulverized coal burner of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, according to the pulverized coal burner of the present invention, the following various excellent effects can be obtained.

The secondary air nozzle is slidably provided with the concentration adjusting ring, so that the pulverized coal can be biased in the primary air for conveyance inside the pulverized coal nozzle to partially increase the concentration. As a result, the combustion of the pulverized coal burner can be stabilized when the load of the mill is low, and the need for providing an external cyclone can be eliminated.

Since there is no need to provide an external cyclone, the configuration can be simplified, the cost can be reduced, and maintenance can be facilitated.

[Brief description of the drawings]

FIG. 1 is a side sectional view of one embodiment of the present invention, and FIG.
FIG. 3 is a view taken along the line II-II, FIG. 3 is a view taken along the line III-III of FIG.
4 is a partially enlarged view showing an operation state of FIG. 1, FIG. 5 is a partially enlarged view showing another operation state of FIG. 1, and FIG. 6 is a side sectional view of another embodiment of the present invention. , FIG. 7 is VII-V of FIG.
FIG. In the figure, 1 is a pulverized coal burner, 2 is a tertiary air nozzle, 3 is a pulverized coal nozzle, 6 is a pulverized coal supply port, 8 is a straight running guide, 9 is a concentration adjusting ring, 21 is a straight running guide, 23 is an inner passage, 24 Indicates an outer passage, and 25 indicates a separation cylinder.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Tanaka 2-29-8 Naruse, Machida-shi, Tokyo (72) Inventor Shoshi 3-2-1-16 Toyosu, Koto-ku, Tokyo Ishikawa Shimaharima Heavy Industries, Ltd. Inside the general office (72) Inventor Keiji Makino 3-2-1-16 Toyosu, Koto-ku, Tokyo Ishikawa Shima-Harima Heavy Industries, Ltd.Toyosu general office (72) Inventor Minoru Kirisawa 3-2-1, Toyosu, Koto-ku, Tokyo Ishikawa Shimaharima Heavy Industries, Ltd., Toyosu General Office (56)

Claims (2)

(57) [Claims] 1. A substantially cylindrical tertiary air nozzle, a pulverized coal nozzle concentrically disposed on the outer periphery of the tertiary air nozzle, and a fine powder formed tangentially at a rear end of the pulverized coal nozzle. A charcoal supply port, a rectilinear guide extending in the front-rear direction attached to the inner surface of the pulverized coal nozzle, and a concentration adjusting ring provided slidably in the front-rear direction in the pulverized coal nozzle along the outer periphery of the tertiary air nozzle. A pulverized coal burner characterized by comprising: 2. A substantially cylindrical tertiary air nozzle, a pulverized coal nozzle concentrically arranged on the outer periphery of the tertiary air nozzle, and a fine powder formed tangentially at a rear end of the pulverized coal nozzle. A coal supply port, a rectilinear guide extending in the front-rear direction attached to the inner surface of the pulverized coal nozzle tip, and a separation tube separating the inside of the pulverized coal nozzle tip provided at the pulverized coal nozzle tip into an inner passage and an outer passage. And a concentration adjusting ring provided on the rear end side of the separation cylinder of the pulverized coal nozzle along the outer periphery of the tertiary air nozzle so as to be slidable in the front-rear direction inside the pulverized coal nozzle. Charcoal burner.