JPH09329304A - Pulverized coal burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit sure ignition and the maintaining of excellent burning condition even when coal, low in volatile constituent and inferior in the property of ignition, is used by a method wherein a nozzle unit, capable of injecting tertiary air directly against the condensed stream of pulverized coal, is formed on required circumferential places of the tip end of a burner inner tube. SOLUTION: The condensed stream of pulverized coal, which is injected from the outside of an intermediate tube 12, is mixed with high-temperature secondary air 4, supplied to the outside of a burner nozzle 9 from a wind box 3 in an area near a nozzle unit 21 so as to be pinched between the secondary air and tertiary air 17, injected from the nozzle unit 21, formed at peripheral required places of the tip end unit of the burner inner tube 6, and, therefore, the condensed stream of pulverized coal is mixed again in an early period with the diluted stream of the pulverized coal, which is injected out of the inner peripheral side of an intermediate tube 12 before being mixed with the high-temperature tertiary air 17 injected out of the central part of tip end of the burner inner tube 6 whereby the condensed stream of the pulverized coal is not cooled by the dilute stream of the pulverized coal. Accordingly, ignition is effected surely and the burner can be applied on the kind of coal of wide range.

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 Pulverized coal combustion, in which pulverized coal pulverized by a mill is mixed with primary air to be supplied to a pulverized coal burner and jetted from the pulverized coal burner to perform floating combustion, is a coal which has been widely and commonly used. Is the combustion method.

An example of the pulverized coal burner device used in the furnace of a pulverized coal combustion type boiler will be described with reference to FIGS. 4 to 6. A throat 2 is formed at a predetermined position on the side wall of the furnace 1, and the throat is formed. A wind box 3 is arranged outside the furnace 1 near the wind box 3 and
To supply the secondary air 4 for combustion to the furnace 1.

At the center of the throat 2 is a wind box 3
A pulverized coal burner 5 penetrating through is provided, and in the center of the pulverized coal burner 5, a burner inner cylinder 6 having a substantially cylindrical shape and a narrowed portion whose diameter sharply decreases toward the distal end at the distal end opening is disposed. An oil burner 7 is inserted at the axial position of the burner inner cylinder 6.

[0005] Outside the burner inner cylinder 6, a burner outer cylinder 8 is disposed concentrically with the burner inner cylinder 6. The burner outer cylinder 8 has a substantially cylindrical base end portion, and extends from an intermediate portion to a distal end. It has a hollow cylindrical shape whose diameter gradually decreases.

A burner nozzle 9 whose diameter decreases sharply toward the tip is attached to the tip opening of the burner outer cylinder 8, and inside the burner nozzle 9, the concentrations of pulverized coal 10 and primary air 11 are changed. An intermediate cylinder 12 is provided for the purpose.

An inlet 19 for the pulverized coal flow extending in the tangential direction is provided at the base end of the burner outer cylinder 8 so as to project therefrom.
A pulverized coal pipe 13 is connected to 9 so as to guide the pulverized coal 10 supplied together with the primary air 11 from a mill (not shown) into the burner outer cylinder 8, and from the intermediate cylinder 12 A concentration adjusting ring 14 is externally fitted at a required position in the longitudinal direction of the burner inner cylinder 6 on the base end side, and the pulverized coal 1 is conveyed to the primary air 11 inside the burner outer cylinder 8.
0 flows over the density adjusting ring 14 and flows.

The outer periphery of the base end portion of the burner inner cylinder 6 and the burner outer cylinder 8
The inner periphery of the base end of the burner inner cylinder 6 made of pulverized coal 10 supplied from the pulverized coal pipe 13 through the pulverized coal flow inlet 19.
A liner 20 made of a wear-resistant material for preventing abrasion of the outer periphery of the base end portion and the inner periphery of the base end portion of the burner outer cylinder 8 is attached.

In the space formed between the throat 2 and the wind box 3, an air register 15 for adjusting the turning force of the secondary air 4 is arranged so as to surround the throat 2 in a circular shape. In addition, a plurality of inner vanes 16 for separating the secondary air 4 into the inner side and the outer side are arranged in the circumferential direction inside the air register 15, and further, the wind box 3 and the base end of the burner inner cylinder 6 are arranged. And the tertiary air tube 1
The tertiary air 17 is guided to the burner inner cylinder 6 by the communication 8.

Pulverized coal burner 5 as shown in FIGS.
In the above, the pulverized coal 10 supplied together with the primary air 11 into the burner outer cylinder 8 from the mill (not shown) through the pulverized coal pipe 13 and the pulverized coal flow inlet 19 to the burner is the burner outer cylinder 8 A swirling force is applied at the rear end portion of the burner, flows in the space between the burner inner cylinder 6 and the burner outer cylinder 8 in the circumferential direction, flows toward the front end, and gets over the concentration adjusting ring 14.

At this time, the pulverized coal 10 is guided to the outer peripheral side inside the burner outer cylinder 8 along the outer peripheral surface of the concentration adjusting ring 14 and the flow passage cross-sectional area is narrowed so that the flow velocity is increased to increase the concentration adjusting ring. Pass through the part where 14 is located.

Immediately after passing through the portion where the concentration adjusting ring 14 is located, the primary air 11 diffuses again into the entire inside of the burner outer cylinder 8. However, the particles of the pulverized coal 10 having a larger specific gravity than that of air have an inertial force. Flow through the outside of the burner outer cylinder 8 as it is, and most of the pulverized coal 10 passes through the outside of the intermediate cylinder 12 in a concentrated state, is jetted from the tip of the burner nozzle 9 to the throat 2, and is mainly supplied from the wind box 3. It is mixed with the secondary air 4 and burned.

As a result, the A / C outside the intermediate cylinder 12 provided at the tip of the burner nozzle 9 (the ratio of combustion air and coal, the lower the value, the higher the coal concentration. ) Can be maintained as low as about 0.5 or less, the ignitability of the pulverized coal 10 can be secured, and stable combustion can be secured even when the mill (not shown) has a low load.

[0014]

In the pulverized coal burner 5 as described above, the high temperature tertiary air 17 is ejected from the center of the tip of the burner inner cylinder 6, and the A / C is ejected from the outside of the intermediate cylinder 12. The pulverized coal concentrated stream having a low temperature is sandwiched between the high temperature secondary air 4 and the high temperature tertiary air 17 to be mixed to stabilize combustion, but as shown in FIGS. 4 to 6, as shown in FIGS. The intermediate cylinder 12 and the burner nozzle 9 are simply arranged concentrically. In fact, as shown in FIG. 6, the pulverized coal concentrated flow ejected from the outside of the intermediate cylinder 12 is in the burner. Before being mixed with the high-temperature tertiary air 17 ejected from the center of the tip of the cylinder 6, the primary air 11 ejected from the inner peripheral side of the intermediate cylinder 12, that is, the A / C is 2-3.
It is remixed at an early stage with a pulverized coal dilute flow having a low coal concentration and a temperature not too high, and is cooled by the pulverized coal dilute flow.

For this reason, there is a drawback that ignition is difficult and coal that can be used is limited, especially when trying to use coal having a low volatile content and poor ignitability.

In view of the above situation, the present invention is capable of reliably igniting and maintaining a good combustion state even when using coal having a low volatile content and poor ignitability, and is suitable for a wide range of coal types. The present invention aims to provide a pulverized coal burner that can be used.

[0017]

SUMMARY OF THE INVENTION According to the present invention, a burner outer cylinder having a burner nozzle integrally attached to the tip end is concentrically arranged outside the burner inner cylinder, and the tip end of the burner inner cylinder and the burner nozzle are arranged. An intermediate cylinder is disposed between the burner inner cylinder and the inner cylinder of the burner, and a concentration adjusting ring is externally fitted to a required position on the base end side of the intermediate cylinder so that the pulverized coal conveyed by the primary air is removed from the burner by the concentration adjusting ring. The pulverized coal concentrated flow is ejected from the outside of the intermediate cylinder by guiding it to the outer peripheral side inside the cylinder, and the pulverized coal dilute flow is ejected from the inside of the intermediate cylinder, and further,
A pulverized coal burner for supplying secondary air from a wind box to the outside of the burner nozzle and ejecting the secondary air from the wind box as tertiary air from the tip of the burner inner cylinder, the tip of the burner inner cylinder The pulverized coal burner is characterized in that a nozzle portion capable of directly injecting tertiary air toward the pulverized coal concentrated flow is formed at a required position in the circumferential direction in.

Further, in the pulverized coal burner, an inner burner cylinder having an outer diameter slightly smaller than the inner diameter of the tip opening of the intermediate cylinder is formed, and a required portion in the circumferential direction at the tip end portion of the inner burner cylinder is located at the tip end side. The nozzle portion can be formed at a position other than the conical portion by forming the conical portion by narrowing the diameter so as to reduce the diameter.

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

By overcoming the density adjusting ring,
The pulverized coal concentrated flow having a low A / C ejected from the outside of the intermediate cylinder is supplied from the wind box to the outside of the burner nozzle in a region near the nozzle portion formed at a required position in the circumferential direction at the tip of the inner burner cylinder. The high temperature secondary air to be mixed is mixed so as to be sandwiched by the tertiary air ejected from the nozzle portion formed at the circumferentially required portion of the tip portion of the burner inner cylinder, so that the conventional intermediate Before the concentrated pulverized coal flow ejected from the outside of the cylinder is mixed with the high-temperature tertiary air ejected from the center of the tip of the inner cylinder of the burner, the pulverized coal dilute flow ejected from the inner peripheral side of the intermediate cylinder. As a result, the pulverized coal is remixed at an early stage and is not cooled by the pulverized coal dilute flow, and ignition is reliably performed.

In the area other than the nozzle portion, as in the conventional case, the pulverized coal concentrated flow ejected from the outside of the intermediate cylinder is heated by the high temperature tertiary air ejected from the center of the tip of the inner cylinder of the burner. Before being mixed with the pulverized coal diluted flow ejected from the inner peripheral side of the intermediate cylinder, it will be remixed in an early stage, but since ignition is reliably performed in the region near the nozzle portion, It becomes a pilot fire and the pulverized coal is surely ignited in a region other than the vicinity of the nozzle portion, and a stable combustion state is obtained as a whole.

As a result, even if coal having a low volatile content and poor ignitability is used, the ignition is surely performed, the usable coal is not limited, and the combustion condition of excessive fuel is locally promoted, resulting in low combustion. NOx is achieved, and moreover, stable combustion is possible when the mill has a lower load than the conventional pulverized coal burner.

Further, an inner cylinder of the burner whose outer diameter is slightly smaller than the inner diameter of the tip opening of the intermediate cylinder is formed, and the required circumferential portion at the tip of the inner cylinder of the burner is reduced in diameter toward the tip side. If the nozzle portion is narrowed to form the conical portion and the nozzle portion is formed at a portion other than the conical portion, the nozzle portion can be formed relatively easily.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an example of an embodiment for carrying out the present invention. In the drawings, the parts denoted by the same reference numerals as those in FIGS. 4 to 6 represent the same things, and the basic structure is Although it is the same as the conventional one shown in FIGS. 4 to 6, the feature of this illustrated example is that, as shown in FIGS. In four points in the example), there is formed a nozzle portion 21 capable of directly ejecting the tertiary air 17 toward the pulverized coal concentrated flow.

In forming the nozzle portion 21, in the illustrated example, a burner inner cylinder 6 having an outer diameter slightly smaller than the inner diameter of the tip opening of the intermediate cylinder 12 is formed, and the tip portion of the burner inner cylinder 6 is formed. The required portion in the circumferential direction is narrowed down so that the diameter is reduced toward the tip side to form the conical portion 22, so that the nozzle portion 21 is formed at a portion other than the conical portion 22.

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

By passing over the concentration adjusting ring 14, the pulverized coal concentrated flow having a low A / C ejected from the outside of the intermediate cylinder 12 is a nozzle formed at a required position in the circumferential direction at the tip of the burner inner cylinder 6. In a region near the portion 21, the high-temperature secondary air 4 supplied from the wind box 3 to the outside of the burner nozzle 9 and the nozzle portion 21 formed at a required position in the circumferential direction at the tip of the burner inner cylinder 6 are ejected. Since it is mixed so as to be sandwiched by the tertiary air 17 that is contained in the burner, the pulverized coal concentrated flow ejected from the outside of the intermediate cylinder 12 is heated to a high temperature, which is ejected from the center of the tip of the burner inner cylinder 6 as in the conventional case. Before being mixed with the tertiary air 17, it is remixed with the lean flow of pulverized coal ejected from the inner peripheral side of the intermediate cylinder 12 at an early stage and cooled by the lean flow of pulverized coal. It is eliminated, so that reliable ignition is performed.

In the area other than the nozzle portion 21, that is, in the region near the conical portion 22, the pulverized coal concentrated flow ejected from the outside of the intermediate cylinder 12 is the center of the tip of the burner inner cylinder 6 as in the conventional case. Before being mixed with the high-temperature tertiary air 17 ejected from the portion, the pulverized coal diluted flow ejected from the inner peripheral side of the intermediate cylinder 12 is remixed in an early stage. Since the ignition is surely performed in the area of (2), it becomes a seed fire and the ignition of the pulverized coal 10 in the area in the vicinity of the conical portion 22 is surely performed, and a stable combustion state is obtained as a whole.

As a result, even if coal having a low volatile content and poor ignitability is used, the ignition is surely performed, the usable coal is not limited, and the combustion condition with excessive fuel is locally promoted, which results in low combustion. NOx can be achieved, and moreover, stable combustion can be achieved when the load of the mill is lower than that of the conventional pulverized coal burner 5.

Further, in the case of the illustrated example, an inner burner cylinder 6 having an outer diameter slightly smaller than the inner diameter of the tip opening of the intermediate cylinder 12 is formed, and a required portion in the circumferential direction at the tip end portion of the inner burner cylinder 6 is formed. The conical portion 22 is narrowed down so that the diameter is reduced toward the tip side.
Since the nozzle portion 21 is formed at a position other than the conical portion 22 by forming the
Can be formed relatively easily.

In this way, even if coal having a low volatile content and poor ignitability is used, it is possible to reliably ignite and maintain a good combustion state, and it is possible to adapt to a wide range of coal types and further NOx.
The reduction and the stabilization of combustion at low load can be further promoted.

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

[0034]

As described above, according to the pulverized coal burner of the present invention, even if coal having a low volatile content and poor ignitability is used, it is possible to reliably ignite and maintain a good combustion state. Therefore, it is possible to obtain an excellent effect that it can be applied to a wide variety of coal types, and that NOx reduction and combustion stabilization under low load can be further promoted.

[Brief description of drawings]

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

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

FIG. 3 is a perspective view showing a tip portion of a burner inner cylinder according to an example of an embodiment of the present invention.

FIG. 4 is a side sectional view of a conventional example.

5 is a view taken along the line VV of FIG.

FIG. 6 is a perspective view showing a tip portion of a burner inner cylinder in a conventional example.

[Explanation of symbols]

 3 Wind Box 4 Secondary Air 5 Pulverized Coal Burner 6 Burner Inner Cylinder 8 Burner Outer Cylinder 9 Burner Nozzle 10 Pulverized Coal 11 Primary Air 12 Intermediate Cylinder 14 Concentration Adjustment Ring 17 Tertiary Air 21 Nozzle Part 22 Cone Part

Claims (2)

[Claims] 1. A burner outer cylinder having a burner nozzle integrally attached to a tip end thereof is concentrically arranged outside the burner inner cylinder, and an intermediate cylinder is arranged between the tip end of the burner inner cylinder and the burner nozzle. A concentration adjusting ring is fitted on a required position on the base end side of the intermediate cylinder of the burner inner cylinder, and the pulverized coal conveyed by the primary air is guided to the outer peripheral side inside the burner outer cylinder by the concentration adjusting ring. A pulverized coal concentrated flow is ejected from the outside of the intermediate cylinder, and a pulverized coal diluted flow is ejected from the inside of the intermediate cylinder, and further, secondary air of the wind box is supplied to the outside of the burner nozzle, and A pulverized coal burner in which secondary air is ejected as tertiary air from the tip of the burner inner cylinder, and the tertiary air is directed to the concentrated pulverized coal flow at the circumferentially required location at the tip of the burner inner cylinder. Pulverized coal burner, characterized in that formed directly jettable nozzle portion Te. 2. A burner inner cylinder having an outer diameter slightly smaller than the inner diameter of the tip opening of the intermediate cylinder is formed, and the circumferentially required portion of the tip end portion of the burner inner cylinder is reduced in diameter toward the tip side. The pulverized coal burner according to claim 1, wherein the nozzle portion is formed at a portion other than the conical portion by forming the conical portion by narrowing down.