JPH0788936B2 - Burner nozzle for pulverized coal combustion - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pulverized coal burning burner nozzle used for efficiently burning pulverized coal or other pulverized fuel having a slow burning rate.

[Prior art and its problems] Pulverized coal used as a heating fuel has an advantage that energy cost is lower than liquid fuel such as heavy oil, but since the burning speed is very slow, pulverized coal is used as fuel. The burner nozzle for burning pulverized coal up to now is usually used as a low-temperature (1500 ° C or lower) heat source such as a steam generation boiler.
In a metal melting furnace that requires high heat transfer characteristics at a temperature higher than this (2000 ° C. or higher), a burner nozzle using a liquid fuel such as heavy oil is mostly used.

Further, in the coal gasification process, etc., these are blown into the reaction furnace using pulverized coal-oxygen as a heat source, but this can be used only when the reaction furnace has a high temperature atmosphere, There was no burner nozzle for pulverized coal combustion that maintained a flame even in a low temperature atmosphere.

Therefore, using only pulverized coal as fuel, the flame temperature is high (2000
It is required to develop a burner nozzle for pulverized coal combustion that can provide a heat source.

[Means for Solving Problems] In order to solve the above problems, the present invention has a flame characteristic equivalent to that of a liquid fuel-oxygen burner, a flame temperature of 2000 ° C. or higher,
The purpose is to provide a pulverized coal combustion burner nozzle that can dissolve metal by pulverized coal combustion.The burner nozzle is provided with a powder fuel supply pipe inside the rear end side of the cylindrical burner nozzle body whose tip opens as a flame jet. The powder fuel supply pipe is provided with a mixed flow jet port extending from the tip opening to the flame jet port, and a conical combustion chamber expanding toward the flame jet port. A primary combustion-supporting gas supply path communicating with the mixed flow jet and a secondary combustion-supporting gas supply path communicating with the combustion chamber are formed around the periphery.
Further, the inlet to the mixed flow jet of the primary combustion-supporting gas supply passage is formed into a conical slit having a gradually smaller diameter toward the mixed flow jet, and the secondary combustion-supporting property is increased. The inlet of the gas supply passage to the combustion chamber is a perforation or a conical slit extending in the flame jet direction and converging on the axis of the burner nozzle body, and the inlet has at least one step in the front-back direction of the combustion chamber. It is characterized by being formed.

In addition to the above, the first of the conical slits
The inlet to the mixed flow jet of the next combustion-supporting gas supply passage is formed at an angle of 15 ° to 45 ° with respect to the axis of the burner nozzle body, and the first hole is formed by the perforation or conical slit. The inlet of the secondary combustion-supporting gas supply passage to the combustion chamber is formed at an angle of 10 ° to 45 ° with respect to the axis of the burner nozzle body, and the conical combustion chamber has a divergence angle. It is characterized by being formed at 20 ° to 90 °.

[Operation] Powder fuel such as pulverized coal is supplied from the powder fuel supply pipe to the first
The secondary combustion-supporting gas is supplied from the primary combustion-supporting gas supply passage to each of the mixed flow jet ports. Here, since the inlet to the mixed flow jet of the primary combustion-supporting gas supply path is a conical slit, the primary combustion-supporting gas is smoothly directed toward the center of the mixed-flow jet. And is thoroughly mixed with the powder. Then, a mixed flow of the powder fuel and the primary combustion-supporting gas is ejected toward the combustion chamber from the mixed flow ejection port.

On the other hand, the secondary combustion-supporting gas is supplied to the combustion chamber from the secondary combustion-supporting gas supply passage, but the inlet of the secondary combustion-supporting gas supply passage to the combustion chamber is Since it extends in the same direction and is converged on the axis of the burner nozzle body, it is supplied toward the central axis of the combustion chamber so as to be smoothly mixed with the flow of the mixed flow.

As a result, it is possible to obtain a high flame temperature and thus to dissolve the metal.

Further, since the inlet to the mixed flow jet of the primary combustion-supporting gas supply passage formed of the conical slit is formed at an angle of 15 ° to 45 ° with respect to the axis of the burner nozzle body, The mixed flow is sufficiently mixed and the generation of incombustibles is eliminated. Further, the inlet to the combustion chamber of the secondary combustion-supporting gas supply path consisting of the perforations or conical slits is formed at an angle of 10 ° to 45 ° with respect to the axis of the burner nozzle body. The secondary combustion-supporting gas is supplied more smoothly to the mixed flow. Further, since the divergence angle of the conical combustion chamber is formed in the range of 20 ° to 90 °, it is possible to prevent the ash content from adhering to the inner surface of the combustion chamber and blocking the flame outlet.

Therefore, by providing at least three of the above conditions, it is possible to significantly improve the combustion efficiency and obtain a higher flame temperature.

[Examples] Hereinafter, first to third examples in which the present invention is applied to a burner nozzle for burning pulverized coal will be described with reference to the drawings. In each of these drawings, the same reference numerals are given to common constituent elements.

(1) First, the first embodiment will be described with reference to FIG.

In the figure, reference numeral 1 shows a main body of a cylindrical burner nozzle according to the present invention. The burner nozzle body 1 is formed by coaxially fitting an inner cylinder 3 shorter than the outer cylinder 2 with the tip (left end in the figure) aligned with the inside of the outer cylinder 2.
A pulverized coal supply pipe (powder supply pipe) 4 is fitted at the rear end (right end in the figure) of the inner cylinder 3, and the pulverized coal supply pipe 4 to the inner cylinder 3 are inserted into the inner cylinder 3. A mixed flow jet port 5 communicating with the pulverized coal supply pipe 4 and a combustion chamber 6 are continuously provided over the tip portion. These mixed flow jets 5 and combustion chambers 6
Are formed coaxially with the burner nozzle body 1.

The mixed flow ejection port 5 is formed of a cylindrical cavity, and the combustion chamber 6 is formed of a conical cavity whose cross section gradually expands from the tip of the mixed flow ejection port 5 toward the tip of the inner cylinder 3. Has become. The spread angle B of the combustion chamber 6 is preferably set in the range of 20 ° to 90 °. Further, the tip of the combustion chamber 6 opens as a flame jet 7.

A space provided between the pulverized coal supply pipe 4 at the rear end of the burner nozzle body 1 and the inner surface of the outer cylinder 2 serves as a combustion-supporting gas (oxygen or oxygen-containing gas) supply port 8. Then, inside the inner cylinder 3, a primary combustion-supporting gas supply passage 9 and a secondary combustion-supporting gas supply which communicate the combustion-supporting gas supply port 8 with the mixed flow jet 5 and the combustion chamber 6 are supplied. A path 10 is formed.

The primary gas supply passage 9 is composed of a cylindrical slit or a plurality of holes formed around the pulverized coal supply pipe 4, and the inlet 9a to the mixed flow jet port 5 at the tip thereof is It is formed in a conical shape having a smaller diameter toward the flow outlet 5. The inlet 9a is formed coaxially with the burner nozzle main body 1, and the angle A of the burner nozzle main body 1 with respect to the axis l is appropriately in the range of 15 ° to 45 °.

Thereby, the pulverized coal supplied from the pulverized coal supply pipe 4,
The primary combustion-supporting gas supplied from the primary combustion-supporting gas supply passage 9 is mixed in the mixed flow jet port 5, and this mixed flow is introduced into the combustion chamber 6 and jetted from the flame jet port 7. . Here, the diameter of the mixed flow ejection port 5 is set to an appropriate size so that the ejection speed of the pulverized coal thus ejected is in the range of 70 to 210 m / sec.

On the other hand, the secondary gas supply passage 10 has a cylindrical slit 11 or a plurality of holes 11 ′ formed along the outer peripheral surface of the inner cylinder 3.
And a plurality of holes (inlets) 12a, 12b, 12c which communicate with the combustion chamber 6 through the slits 11 or the holes 11 '. On the flame ejection port 7 side of the slit 11 or the hole 11 ', a chamber 11a wider than the combustion-supporting gas supply port 10 side is formed. The holes 12a, 12b, 12c are formed in parallel with each other in three stages in the front-rear direction so as to extend toward the flame jet port 7 and converge toward the axis l of the burner nozzle body 1.
The angle C of each of the holes 12a, 12b, 12c with respect to the axis l of the burner nozzle body 1 is preferably in the range of 10 ° to 45 °.

According to the burner nozzle for pulverized coal spraying configured as described above, pulverized coal is sprayed from the pulverized coal supply pipe 4 and primary combustion-supporting gas is injected from the primary combustion-supporting gas supply passage 9 in a mixed flow manner. The mixed flow is supplied to the outlet 5 and is jetted into the combustion chamber 6 at a flow rate of 70 to 210 m / sec. In addition, the secondary combustion-supporting gas is
Slit 11 or hole 1 in the secondary combustion supporting gas supply passage 10
1 ', after passing through the chamber 11a, the combustion chamber 6 from the holes 12a, 12b, 12c.
Erupted into. As a result, the mixed flow of pulverized coal and the primary combustion-supporting gas and the secondary combustion-supporting gas are completely mixed in the combustion chamber 6, and ignition and combustion are possible.

At the conical inlet 9a of the primary combustion-supporting gas supply passage 9, if the angle A is smaller than 15 °, the mixed flow jet port 5
In the combustion chamber 6, the ash, which is an incombustible component of the pulverized coal, becomes larger than 45 ° because the ignition of the combustion chamber 6 becomes difficult due to insufficient mixing of the pulverized coal and the primary combustion-supporting gas. Adheres to and deteriorates combustion. Further, if the flow velocity of the mixed flow of pulverized coal and the primary combustion-supporting gas is outside the range of 70 to 210 m / sec as described above, it becomes difficult to ignite in the combustion chamber 6,
It may also cause blockage. Further, if the spread angle C of the combustion chamber 6 is smaller than 20 °, ash which is an incombustible component of pulverized coal may adhere to the inner surface of the combustion chamber 6 and the flame jet port 7 may be blocked. If it is large, flame does not ignite in the combustion chamber 6 and flame blows off.

Therefore, the angle A of the inlet 9a of the primary combustion-supporting gas supply passage 9 is set to 15 ° to 45 °, and the jet speed of the mixed flow is 70 to 21.
The diameter of the mixed flow jet port 5 is set to 0 m / sec, and the spread angle C of the combustion chamber 6 is set to 20 ° to 90 °, so that the ignition of the pulverized coal in the combustion chamber 6 is performed. This is easily possible and a stable combustion state is maintained.

Further, the mixing of the secondary combustion-supporting gas to the mixed flow is sequentially performed from the holes 12a, 12b, 12c of the secondary combustion-supporting gas supply passage 10, and at this time, the holes 12a, 12b, 12c are Flame spout 7
The secondary combustion-supporting gas smoothly mixes with the mixed flow without hindering the flow of the mixed flow because it is formed so as to extend in the direction and converge toward the axis l of the burner nozzle body 1.

Therefore, according to the burner nozzle for burning pulverized coal of the present embodiment, the primary and secondary combustion-supporting gases are completely mixed with the pulverized coal, and the mixed flow is formed so as to be concentrated on the central axis. Since it is burned by being burned, the flame density is high, and a high flame temperature can be obtained, so that the metal can be melted.

(2) Next, a second embodiment of the present invention will be described with reference to FIGS. 2 and 3.

In the second embodiment, a primary combustion-supporting gas supply passage 20 is provided around the pulverized coal supply pipe 4 from the combustion-supporting gas (oxygen or oxygen-containing gas) supply port 8 to the mixed flow jet port 5.
However, it is different from the first embodiment.

That is, the primary combustion-supporting gas supply passage 20 has a slit 20a or a plurality of holes 20a 'formed coaxially with the burner nozzle body 1 around the pulverized coal supply pipe 4, and the slit 20a or a plurality of the slits 20a. Chamber connected to the tip of each hole 20a '
20b, an inlet 20c to the mixed flow jet port 5 which is formed in a conical shape as in the first embodiment, and a hole 20d which communicates the rear end of the inlet 20c with the chamber 20b. . Then, as shown in FIG. 3, the holes 20d are opened at a plurality of portions equally divided by the circumference with respect to the inner peripheral surface of the rear end of the inlet 20c, and moreover, along the tangential direction of the inner peripheral surface. Has been drilled.

According to the burner nozzle of the second embodiment, the primary combustion-supporting gas passing through each hole 20d of the primary combustion-supporting gas supply passage 20 becomes a swirl flow and enters the mixed flow jet port 5 from the inlet 20c. Continue
As a result, the pulverized coal supplied from the pulverized coal supply pipe 4 at the mixed flow jet port 5 is sufficiently mixed with the primary combustion-supporting gas, and the combustion efficiency is further improved.

In the following, a concrete example 3 is carried out based on the second embodiment.
Here are two examples.

Entrance to the mixed flow jet 5 of the primary combustion-supporting gas supply passage 20
The angle A of 20a is 30 °, the spread angle B of the combustion chamber 6 is 30 °,
The holes 12a, 12b, 12c, which are the inlets from the chamber 11a of the secondary combustion-supporting gas supply passage 10 to the combustion chamber 6, are formed in three stages as in FIG.
The angle C was set to 30 °.

Then, pulverized coal is supplied at a rate of 20 kg / hr from the pulverized coal supply pipe 4, and room temperature oxygen is supplied from the primary combustion-supporting gas supply passage 20.
These mixed flows were jetted into the combustion chamber 6 from the mixed flow jet port 5 at 110 m / sec, and oxygen was supplied to the combustion chamber 6 from the secondary combustion supporting gas supply passage 10. Hold this state 900
When burned in a furnace at ℃, ignition occurred in the combustion chamber 6, and a flame of 2000 ℃ or more was stably obtained.

Entrance to the mixed flow jet 5 of the primary combustion-supporting gas supply passage 20
The angle A of 20a is 15 °, the spread angle B of the combustion chamber 6 is 60 °,
The conditions of each hole 12a, 12b, 12c were the same as above.

Then, pulverized coal is supplied at a rate of 30 kg / hr from the pulverized coal supply pipe 4 and oxygen at room temperature is supplied from the primary combustion-supporting gas supply passage 20, and the mixed flow of these is supplied at a mixed flow jet port 5 at 147 m / sec. And was supplied with oxygen from the secondary combustion-supporting gas supply passage 10 to the combustion chamber 6. When this state was maintained and combustion was carried out in a furnace at 900 ° C., ignition occurred in the combustion chamber 6 and a flame of 2000 ° C. or higher was stably obtained.

Entrance to the mixed flow jet 5 of the primary combustion-supporting gas supply passage 20
The angle A of 20a is 30 °, the spread angle B of the combustion chamber 6 is 45 °,
The holes serving as the inlets of the secondary combustion-supporting gas supply passage 11 to the combustion chamber 6 were formed in four stages, and the angle C between them was set to 30 °.

And pulverized coal at 150 kg / hr from the pulverized coal supply pipe 4,
Oxygen preheated to 300 ° C. is supplied from the primary combustion-supporting gas supply passage 20, and a mixed flow of these is ejected from the mixed-flow jet outlet 5 at 163 m / sec, and the secondary combustion-supporting gas supply passage 10 From above, oxygen was supplied to the combustion chamber 6. When this state was maintained and combustion was carried out in the furnace, ignition occurred in the combustion chamber 6 and a flame of 2200 ° C. or higher was stably obtained.

(3) Next, a third embodiment of the present invention will be described with reference to FIG.

In the third embodiment, the secondary combustion-supporting gas supply passage 30 provided from the combustion-supporting gas supply port 8 to the combustion chamber 6 is provided.
However, it is different from the second embodiment.

That is, the secondary combustion-supporting gas supply passage 30 is connected to the cylindrical slit 30a or hole 30a 'formed along the outer peripheral surface of the inner cylinder 3 and the tip of the slit 30a or hole 30a'. Chamber 30b, an inlet 30c to the combustion chamber 6 formed of a conical slit, and a hole 3 for communicating the inlet 30c with the chamber 30b.
It consists of 0d.

The inlet 30c has a conical shape that extends in the direction of the flame outlet 7 and converges toward the axis l of the burner nozzle body 1, and the angle D with respect to the axis l depends on the holes 12 of the first embodiment.
As with a, 12b, and 12c, it is appropriate to set at 10 ° to 45 °. Further, the holes 30d are opened at a plurality of positions equally circumferentially with respect to the inner peripheral surface of the rear end portion of the inlet 30c, and are directed in the tangential direction of the inner peripheral surface. by this,
When passing through the hole 30d and entering the inlet 30c, the secondary combustion-supporting gas becomes a swirl flow and is further supplied to the combustion chamber 6 as a swirl flow. In addition, the entrance 30 consisting of a conical slit
A plurality of c may be formed in the front-rear direction of the combustion chamber 6 from the chamber 30b.

According to the burner nozzle of the third embodiment, the secondary combustion-supporting gas supplied to the combustion chamber 6 from the inlet 30c of the secondary combustion-supporting gas supply passage 30 to the combustion chamber 6 is pulverized coal and pulverized coal. By providing a swirling flow without disturbing the flow of the mixed flow of the primary combustion-supporting gases, the mixed flow is smoothly mixed in the center of the combustion chamber 6 without deviation in the radial direction, and ,
The mixed flow concentrates in the center of the flame.

Hereinafter, an example specifically implemented based on the second embodiment will be described.

Inlet 20a of mixed flow ejection port 5 of primary combustion-supporting gas supply passage 20
Angle A of 30 °, spread angle B of combustion chamber 6 30 °, second
The angle D of the inlet 30c formed by the slit of the next combustion-supporting gas supply passage 30 was set to 15 °.

Then, the pulverized coal is supplied at a rate of 30 kg / hr from the pulverized coal supply pipe 4 and 8
Oxygen preheated to 00 ° C. is supplied from the primary combustion-supporting gas supply passage 20 to eject the mixed flow of these at a flow rate of 185 m / sec from the mixed-flow jet port 5 and the secondary combustion-supporting gas supply passage 30. From
Oxygen was supplied to the combustion chamber 6. When this state was maintained and an ignition source was applied in the atmosphere, the combustion occurred, and thereafter, the ignition source or the combustion chamber 6 continuously burned. This flame was able to melt the stainless steel.

[Effects of the Invention] As described above, according to the pulverized coal combustion burner nozzle of the present invention, the powdered fuel is supplied from the powdered fuel supply path to the first
The secondary combustion-supporting gas is supplied from the primary combustion-supporting gas supply passage to each of the mixed flow jet ports. Here, since the inlet to the mixed flow jet of the primary combustion-supporting gas supply path is a conical slit, the primary combustion-supporting gas is smoothly directed toward the center of the mixed-flow jet. Supplied. Then, the mixed flow of the powdered fuel and the primary combustion-supporting gas is ejected from the mixed flow ejection port toward the combustion chamber.

On the other hand, the secondary combustion-supporting gas is supplied to the combustion chamber from the secondary combustion-supporting gas supply passage, but the inlet of the secondary combustion-supporting gas supply passage to the combustion chamber is Since it extends in the direction and is converged on the axis of the burner nozzle body, it is smoothly supplied toward the center of the combustion chamber without disturbing the flow of the mixed flow.

As a result, it is possible to obtain a high flame temperature and thus to dissolve the metal.

Further, since the inlet to the mixed flow jet of the primary combustion-supporting gas supply passage formed of the conical slit is formed at an angle of 15 ° to 45 ° with respect to the axis of the burner nozzle body, The mixed streams are mixed more thoroughly and the generation of incombustibles is eliminated. Further, the inlet of the secondary combustion-supporting gas supply passage formed of the perforations or conical slits to the combustion chamber is 10 ° to the axis of the burner nozzle body.
The secondary combustion-supporting gas is smoothly supplied by the mixed flow because it is formed at an angle of 45 °. Further, since the divergence angle of the conical combustion chamber is formed in the range of 20 ° to 90 °, it is possible to prevent the ash content from adhering to the inner surface of the combustion chamber and blocking the flame ejection port.

Therefore, by providing at least three of the above conditions, combustion efficiency is significantly improved and a higher flame temperature can be obtained.

[Brief description of drawings]

1 is a side sectional view showing a first embodiment of the present invention, FIG. 2 is a side sectional view showing a second embodiment of the present invention, and FIG.
A sectional view taken along the line III-III and FIG. 4 are side sectional views showing a third embodiment of the present invention. 1 ... Burner nozzle body, 4 ... Pulverized coal supply pipe (powder fuel supply pipe), 5 ... Mixed flow jet port, 6 ... Combustion chamber, 7 ...
… Flame outlet, 9, 20 …… Primary combustion-supporting gas supply path, 9
a, 20c ... inlet to the mixed flow jet of the primary combustion-supporting gas supply passage, 10, 30 ... secondary combustion-supporting gas supply passage, 12a, 12b,
12c, 30c ... Inlet to the combustion chamber of the secondary combustion supporting gas supply passage.

Claims (4)

[Claims] 1. A powder fuel supply pipe is provided inside a rear end side of a cylindrical burner nozzle main body whose tip opens as a flame jet, and a mixed flow extends from the tip opening of the powder fuel feed pipe to the flame jet. A primary combustion-supporting gas supply passage, in which a combustion chamber having a conical shape that expands toward the flame ejection port is continuously provided, and which communicates with the mixed flow ejection port around the powder fuel supply pipe. And a secondary combustion-supporting gas supply path communicating with the combustion chamber is formed. Further, the inlet of the primary combustion-supporting gas supply path to the mixed flow jet is directed toward the mixed flow jet. Therefore, the inlet of the secondary combustion-supporting gas supply passage to the combustion chamber is formed in a conical slit having a gradually smaller diameter, and extends toward the flame outlet, and is a hole or a cone that converges on the axis of the burner nozzle body. Shaped slit, and this entrance Burner nozzles for pulverized coal combustion, characterized in that it is formed at least one step in the longitudinal direction of the combustion chamber. 2. An inlet of the primary combustion-supporting gas supply passage formed of the conical slit to the mixed-flow jet outlet is formed at an angle of 15 ° to 45 ° with respect to the axis of the burner nozzle body. The burner nozzle for pulverized coal combustion according to claim 1, characterized in that 3. The inlet to the combustion chamber of the secondary combustion-supporting gas supply passage formed of the perforated or conical slit is formed at an angle of 10 ° to 45 ° with respect to the axis of the burner nozzle body. The burner nozzle for pulverized coal combustion according to claim 1, characterized in that 4. The burner nozzle for pulverized coal combustion according to claim 1, wherein the conical combustion chamber is formed with a spread angle of 20 ° to 90 °.