JPH0626614A - Pulverized coal burner - Google Patents

Abstract

PURPOSE:To provide a pulverized coal burner capable of accommodating a low load operation of a coal fired boiler, showing a small size and having a simple structure. CONSTITUTION:A pulverized coal burner has a substantial cylindrical inner cylinder 12 having its base end closed and its extremity end released and further has a plurality of injection holes 15 coaxially enclosing the outer circumference of a base end of the inner cylinder, its base end and its extremity end closed and directed in a tangential direction around the inner cylinder. It is comprised of a base end intermediate cylinder 14 having a substantial cylindrical shape so as to cause air to be supplied into it, a substantial cylindrical extremity end intermediate cylinder 16 having its base end and extremity end released, and an outer cylinder 18 coaxially enclosing coaxially the base end intermediate cylinder and the extremity end intermediate cylinder, having its extremity end released and having air containing pulverized coal supplied to the base end portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized coal burner,
More specifically, it relates to a pulverized coal burner for a coal-fired boiler.

[0002]

2. Description of the Related Art A conventional pulverized coal burner for a coal-fired boiler is
As shown in FIG. 2, a fixed inner cylinder 1 and an outer cylinder 2 and an axially movable movable inner cylinder 3 provided at the tip of the inner cylinder are provided, and supply is provided between the inner cylinder and the outer cylinder. The air containing the pulverized coal (pulverized coal flow) flows axially between the inner cylinder and the outer cylinder, is injected from the tip of the burner, and the inner pulverized coal is ignited by the ignition burner 4 provided inside the inner cylinder. However, the combustion flame was injected into the combustion chamber 6 of the boiler through the boiler throat 5.

[0003]

In recent years, even pulverized coal burning boilers are required to have load characteristics equivalent to those of heavy oil combustion boilers. Therefore, in pulverized coal burners especially during low load operation of boilers. It is required to minimize the amount of combustion. In order to reduce the amount of combustion in the above-described conventional pulverized coal burner, a means has been taken to reduce the amount of pulverized coal flow by moving the movable inner cylinder in the axial direction to narrow the area of the jet outlet at the tip of the burner. . However, by such means,
If the area of the ejection port at the tip of the boiler is too narrow, the amount of the pulverized coal flow in the supply line to the burner becomes small, and there is a problem that the pulverized coal cannot be pneumatically transported. In order to avoid this problem, a means for reducing the amount of pulverized coal contained in the pulverized coal flow by making the amount of pulverized coal flow sufficient for pneumatic transportation has been proposed and partially implemented. However, when the amount of combustion is reduced by such means, there is a problem that the pulverized coal becomes thin and stable combustion cannot be performed.

Further, in order to solve these problems, a pulverized coal burner in which a cyclone separator is provided in addition to the burner body and a pulverized coal pipe is provided with a switching damper has been proposed. In many cases, the installation of the burner becomes difficult due to the large size, the number of parts is large, the structure is complicated, and wear and blockage easily occur during operation.

The present invention was created to solve the above problems. That is, an object of the present invention is to provide a pulverized coal burner that can cope with low-load operation of a coal-fired boiler and that is small in size and has a simple structure.

[0006]

According to the present invention, a substantially cylindrical inner cylinder having a closed base end and an open front end and a base end outer periphery of the inner cylinder are coaxially surrounded so that the base end and the distal end are Closed,
In addition, a base end intermediate cylinder having a plurality of tangential ejection holes in the periphery thereof and having an air supply inside, and a distal end outer circumference of the inner cylinder are coaxially surrounded, and a base end is formed. And a substantially cylindrical tip intermediate cylinder having an open tip, and the base intermediate cylinder and the tip intermediate cylinder are coaxially surrounded, and the tip is opened so that air containing pulverized coal is supplied to the base portion. A pulverized coal burner is provided which comprises an outer cylinder.

According to a preferred embodiment of the present invention, the outer cylinder has an air supply port containing pulverized coal provided in the same tangential direction as the ejection hole. Further, it is preferable to provide an elongated ignition burner extending in the axial direction inside the inner cylinder.

[0008]

According to the above-described structure of the present invention, air is tangentially ejected between the outer cylinder and the base intermediate cylinder through the plurality of ejection holes provided in the base intermediate cylinder. The jetted air merges with the pulverized coal flow supplied to the base end portion of the outer cylinder, and swirls the pulverized coal flow violently. Due to this swirling, the pulverized coal contained in the pulverized coal flow moves outward in the radial direction due to centrifugal force, and at the same time, moves axially along the inner surface of the outer cylinder, and between the intermediate tip cylinder and the outer cylinder. It jets while turning from the tip of the burner. On the other hand, the air inside, in which the pulverized coal is thinned by the centrifugal force, is ejected from the tip of the burner through the space between the inner cylinder and the tip intermediate cylinder.

Due to such an action, even if the concentration of pulverized coal in the pulverized coal flow supplied to the base end portion of the outer cylinder is low, the pulverized coal flow ejected from the tip of the burner has a cylindrical or conical shape. A pulverized coal-rich portion is formed. Therefore,
Stable combustion of pulverized coal can be performed in such a portion. Furthermore, if the outer cylinder has a supply port in the same tangential direction as the ejection hole of the base end intermediate cylinder, the pulverized coal flow flows into the base end portion of the outer cylinder while swirling in the same direction. The swirling of the coal flow becomes more vigorous, and the burner tip can form a portion having a high pulverized coal concentration.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall sectional view of a pulverized coal burner according to the present invention. In this figure, a pulverized coal burner 10 according to the present invention coaxially surrounds a substantially cylindrical inner cylinder 12 having a closed base end and an open front end, and an outer circumference of a base end portion of the inner cylinder 12, and the base end and the front end are closed. Substantially cylindrical proximal end intermediate cylinder 14
And a substantially cylindrical distal end intermediate cylinder 16 having a proximal end and a distal end open, and a proximal end intermediate cylinder 14 and a distal intermediate cylinder 16 coaxially surrounding the distal end outer circumference of the inner cylinder 12, and the distal end is open. The outer cylinder 18 is provided. Inner cylinder 12, tip intermediate cylinder 16,
The tip portion of the outer cylinder 18 is preferably bent into a frustoconical shape as shown in the figure. As a result, the flow of the fine powder flow from the tip of the burner can be made substantially conical. The tip intermediate cylinder 16 is preferably located substantially in the middle of the inner cylinder 12 and the outer cylinder 18, but the invention is not limited to this, and the distance between the outer cylinder 18 and the outer cylinder 18 may be widened, for example.

The base intermediate cylinder 14 has a plurality of tangential ejection holes 15 around its circumference. Further, an air supply line 22 connecting the wind box 20 and the base end intermediate cylinder 14 is provided so as to supply air into the base end intermediate cylinder 14, and a damper 23 for adjusting the amount of air is provided in the middle of this line.
Is provided. With this configuration, air can be ejected tangentially between the outer cylinder 18 and the base intermediate cylinder 14 through the ejection holes 15.

The outer cylinder 18 has a pulverized coal flow supply port 18a which is provided in the same tangential direction as the ejection hole 15. Thereby, the fine powder flow can be swirled and supplied. Furthermore,
An elongated ignition burner 19 extending axially inside the inner cylinder 12.
Equipped with. Further, an air supply line 2 connecting the wind box 20 and the inner cylinder 12 so as to supply air to the inner cylinder 12.
4 is provided, and a damper 25 for adjusting the amount of air is provided in the middle of this line.

According to the above configuration of the present invention, air is tangentially ejected between the outer cylinder and the base intermediate cylinder through the plurality of ejection holes provided in the base intermediate cylinder. The jetted air merges with the pulverized coal flow supplied to the base end portion of the outer cylinder, and swirls the pulverized coal flow violently. Due to this swirling, the pulverized coal contained in the pulverized coal flow moves outward in the radial direction due to centrifugal force, and at the same time, moves axially along the inner surface of the outer cylinder, and between the intermediate tip cylinder and the outer cylinder. It jets while turning from the tip of the burner. On the other hand, the air inside, in which the pulverized coal is thinned by the centrifugal force, is ejected from the tip of the burner through the space between the inner cylinder and the tip intermediate cylinder.

Due to this action, even if the concentration of pulverized coal in the pulverized coal flow supplied to the base end portion of the outer cylinder is low, the pulverized coal flow ejected from the tip of the burner has a cylindrical or conical shape. A pulverized coal-rich portion is formed. Therefore,
Stable combustion of pulverized coal can be performed in such a portion. Furthermore, if the outer cylinder has a supply port in the same tangential direction as the ejection hole of the base end intermediate cylinder, the pulverized coal flow flows into the base end portion of the outer cylinder while swirling in the same direction. The swirling of the coal flow becomes more vigorous, and the burner tip can form a portion having a high pulverized coal concentration.

[0015]

As described above, according to the present invention, it is possible to provide a pulverized coal burner which can cope with a low load operation of a coal-fired boiler and which is small in size and simple in structure.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a pulverized coal burner according to the present invention.

FIG. 2 is an overall sectional view of a conventional pulverized coal burner.

[Explanation of symbols]

 1 Inner Cylinder 2 Outer Cylinder 3 Movable Inner Cylinder 4 Ignition Burner 5 Boiler Throat 6 Boiler Combustion Chamber 10 Pulverized Coal Burner 12 Inner Cylinder 14 Base End Intermediate Cylinder 16 Tip Middle Cylinder 18 Outer Cylinder 20 Wind Box 22, 24 Air Supply Line 23 , 25 damper

Claims (3)

[Claims] 1. A substantially cylindrical inner cylinder having a closed base end and an open front end, and a base end outer periphery of the inner cylinder coaxially surrounding the base end and the front end are closed, and a tangential direction is provided around the circumference. A substantially cylindrical base end intermediate cylinder having a plurality of ejection holes and being supplied with air inside, and an outer circumference of a tip end portion of the inner cylinder being coaxially surrounded, and a base end and a tip end being substantially open. A cylindrical tip intermediate tube, and an outer tube that coaxially surrounds the base intermediate tube and the tip intermediate tube, is open at the tip, and is supplied with air containing pulverized coal at the base end. Pulverized coal burner characterized by that. 2. The pulverized coal burner according to claim 1, wherein the outer cylinder has a supply port for air containing pulverized coal which is provided in the same tangential direction as the ejection hole. 3. The pulverized coal burner according to claim 1, further comprising an elongated ignition burner extending in the axial direction inside the inner cylinder.