JP4506337B2 - Pulverized coal blowing burner for metallurgical furnace and method for blowing pulverized coal into metallurgical furnace - Google Patents

Description

  The present invention relates to a pulverized coal injecting burner for injecting pulverized coal into a furnace through a tuyere in a metallurgical furnace such as a blast furnace and a method for injecting pulverized coal into a metallurgical furnace using the same.

In blast furnace operation, it is common to inject pulverized coal as an alternative fuel for coke, and recently there is an example in which an operation exceeding a pulverized coal ratio of 260 kg per ton of pig iron is performed (for example, see Non-Patent Document 1). .
However, there is a possibility that further reduction of coke usage will be required in the future due to circumstances such as the future supply and demand of coke, aging of coke ovens, and suppression of carbon dioxide generation, It is considered necessary to perform pulverized coal injection.
“Materials and Processes Vol.11 (1998)” p834

In general, pulverized coal is blown into the blast furnace along with hot air through a pulverized coal blowing burner inserted through a blow pipe attached to the tuyere, but various problems occur as the amount of pulverized coal increases. To do.
One of these concerns unburned char generation. That is, as the amount of pulverized coal injected increases, the excess oxygen ratio at the tuyere decreases, so the combustion rate of pulverized coal decreases and the amount of unburned char that cannot be burned in the raceway increases.

  The generated unburned char may be preferentially consumed by the solution loss reaction at the bottom of the furnace, but its consumption is limited. Therefore, when the amount of unburned char generated exceeds the in-furnace limit consumption, unburned char is discharged as dust from the top of the furnace, leading to a reduction in coke replacement rate and an increase in fuel ratio. In addition, if the generated unburned char accumulates in the core or the cohesive zone root, the furnace condition becomes unstable and the productivity decreases due to deterioration of air permeability and liquid permeability.

Therefore, in order to realize a stable operation of a large quantity of pulverized coal, it is essential to keep the amount of unburned char generated below the consumption limit in the furnace. To that end, the combustion rate of pulverized coal in the raceway is essential. Improvement is needed.
Conventionally, in order to improve the combustion rate of pulverized coal, it is considered effective to increase the mixing efficiency of the injected pulverized coal particles and hot air, or to increase the contact efficiency between the pulverized coal particles and oxygen. From this viewpoint, various techniques have been proposed.

For example, in Patent Documents 1 and 2, the pulverized coal blowing lance (burner) has a concentric double pipe structure, pulverized coal is supplied from the inner pipe, and oxygen or oxygen-enriched air is supplied from the outer pipe, respectively. A technique has been shown in which the combustion rate of pulverized coal is improved by increasing the oxygen concentration. In Patent Document 3, the pulverized coal blowing lance has a concentric triple pipe structure, and pulverized coal and oxygen or oxygen-enriched air are supplied from the inner tube and the outer tube, respectively, and air is supplied from the outermost tube. The technique which aimed at the further improvement of the pulverized coal combustion rate by doing is shown.
Japanese Patent Laid-Open No. 02-213406 Japanese Patent Application Laid-Open No. 06-10092 Japanese Patent Application Laid-Open No. 11-343511

  However, just using a lance having a concentric double pipe structure as in the technology of Patent Document 1, pulverized coal fed from the lance is oxygen gas (oxygen or oxygen-enriched air) fed from the outer pipe. Since it mixes rapidly with the surrounding hot air before mixing with the pulverized coal, the effect of increasing the oxygen concentration around the pulverized coal is greatly diminished, and an effective improvement in the pulverized coal combustion rate cannot be expected.

  On the other hand, in the technique of Patent Document 2, by positioning the tip of the inner tube of the lance 15 to 105 mm inward from the tip of the outer tube, before the pulverized coal is mixed with the oxygen gas fed from the outer tube, The problem of rapid mixing is improved to some extent, so that the initial flammability until the oxygen delivered from the outer tube is consumed is improved. However, with regard to the combustibility of pulverized coal after that, since the dispersibility of the pulverized coal blown out from the lance is low, oxygen in the hot air cannot be used effectively, and sufficient combustibility cannot be obtained. .

  In addition, the technology of Patent Document 3 is that the pulverized coal and oxygen gas fed from the inner pipe and the outer pipe are mixed and burned while diffusing as a jet, and the air is fed from the outer pipe to the jet region. Intrusion of hot air having a low oxygen concentration is prevented, and as a result, combustibility of pulverized coal is improved. However, this technique also improves the initial combustibility until the oxygen supplied from the outer pipe is consumed, as in Patent Document 2, but the dispersibility of the pulverized coal is low, so the oxygen in the hot air is effective. There is a problem that it cannot be used.

Therefore, the object of the present invention is to improve the contact efficiency between pulverized coal and hot air or oxygen gas, and can effectively increase the combustion rate of pulverized coal, thereby enabling the injection of a large amount of pulverized coal. It is to provide a pulverized coal blowing burner.
Another object of the present invention is to provide a method for blowing pulverized coal into a metallurgical furnace using such a pulverized coal blowing burner.

The features of the present invention for solving such problems are as follows.
[1] In a pulverized coal blowing burner for blowing pulverized coal through a tuyere into a metallurgical furnace,
The tip side portion of the pulverized coal blowing pipe constituting the burner main body is a reduced diameter pipe portion whose inner diameter is gradually reduced toward the pipe end side, and a pipe end portion connected to the reduced diameter pipe portion, the inner diameter of the pipe A pulverized coal-injection burner for a metallurgical furnace, comprising a diameter-expanded pipe portion that gradually increases in diameter toward the end, and having a spread angle θ with respect to the pipe axis of the inner diameter of the diameter-expanded pipe portion being less than 10 °.

[2] A pulverized coal-injection burner for metallurgical furnaces characterized in that, in the burner of [1], the spread angle θ of the inner surface of the expanded pipe portion with respect to the tube axis is 5 ° or more and less than 10 °.
[3] In the burner according to [1] or [2], pulverized coal blowing for a metallurgical furnace having an equal-diameter pipe portion having a constant inner diameter between the reduced-diameter pipe portion and the enlarged-tube portion. burner.
[4] In any of the burners of the above [1] to [3], the inner diameter D ₂ of the burner tip inboard end of the inner diameter D ₁ and the reduced tube of the burner near the rear end edge portion of the reduced tube portion below A pulverized coal-injection burner for metallurgical furnaces characterized by satisfying the formula (1).
0.6 ≦ D ₂ / D ₁ ≦ 0.8 (1)

[5] In any one of the burners of the above [1] to [4], the inner diameter D ₁ and the radially enlarged tube inner diameter D ₃ of the tip of the burner near the rear end edge portion of the radially reduced tube section the following formula (2) Satisfactory pulverized coal-injection burner for metallurgical furnaces.
_{D 1 / D 3 ≦ 1.0 ...} (2)
[6] In the burner according to any one of [1] to [5], the burner main body has a double pipe structure including an inner pipe and an outer pipe, and the inner pipe constitutes a pulverized coal blowing pipe, A pulverized coal blowing burner for a metallurgical furnace, wherein the outer tube constitutes a combustion supporting gas blowing tube.
[7] In the burner according to any one of [1] to [5], the burner main body has a double pipe structure including an inner pipe and an outer pipe, and the inner pipe constitutes a pulverized coal blowing pipe, A pulverized coal blowing burner for metallurgical furnace, wherein the outer pipe constitutes a flow path for cooling fluid.

[8] In the burner according to any one of [1] to [6], the pulverized coal blowing tube has a structure having a flow path for cooling fluid inside the tube wall. Blow burner.
[9] In the burner according to any one of [1] to [5], the burner body has a triple tube structure including an inner tube, an outer tube, and an outermost tube, and the inner tube is a pulverized coal blowing tube. A pulverized coal blowing burner for a metallurgical furnace, wherein the outer tube forms a combustion-supporting gas blowing tube, and the outermost tube forms a cooling fluid flow path.

[10] A method for injecting pulverized coal into a metallurgical furnace using the pulverized coal injecting burner according to any one of [1] to [9],
Inserting the tip side of the burner body of the pulverized coal blowing burner into the tuyere of the metallurgical furnace or a blow pipe connected thereto, and blowing the pulverized coal into the metallurgical furnace through the tuyere A pulverized coal injection method into a metallurgical furnace .

According to the pulverized coal blowing burner of the present invention, the pulverized coal flow (pulverized coal + carrier gas) conveyed in the pulverized coal blowing tube is compressed in the burner axial direction in the reduced diameter pipe portion, and then in the expanded diameter pipe portion. By being suddenly released from the compressed state, a pulverized coal flow having a dispersed flux cross section along the inner surface of the expanded pipe portion is formed. The dispersed pulverized coal flow is blown out from the tip of the pulverized coal blowing pipe, so that the contact efficiency between the pulverized coal and the oxygen in the hot air is effectively increased, and the combustibility of the pulverized coal is improved.
In addition, when oxygen gas is fed from the outer pipe outside the pulverized coal blowing pipe to the burner tip, the oxygen gas reliably collides with the pulverized coal flow blown in a dispersed state from the burner tip and Mixing (contacting) with oxygen is efficiently performed, so that oxygen is effectively used for combustion of pulverized coal, and the combustion rate of pulverized coal is effectively improved. Moreover, even after the oxygen is consumed, the contact efficiency between the pulverized coal flow and the oxygen in the hot air is improved, and the combustibility of the pulverized coal is also improved.
As a result of the above, by using the pulverized coal injection burner of the present invention, the combustion rate of pulverized coal can be greatly improved compared to conventional burners, and the amount of pulverized coal injection into the blast furnace is greatly increased compared to the conventional one. It becomes possible to do.

1 and 2 show an embodiment of the pulverized coal blowing burner of the present invention. FIG. 1 is a longitudinal sectional view of the pulverized coal blowing burner. FIG. 2 is a blast furnace to which the pulverized coal blowing burner A of the present invention is attached. It is a longitudinal cross-sectional view of a tuyere part.
In FIG. 1, reference numeral 1 denotes a burner body having a concentric double pipe structure. The burner body 1 is composed of an pulverized coal blowing tube 2 and an outer tube 3 which are inner tubes, and this outer tube 3 (pulverized coal blowing tube 2 and The flow path 4) between the outer tubes 3 constitutes a combustion-supporting gas blowing tube. The combustion-supporting gas means oxygen or an oxygen-containing gas, and usually oxygen or oxygen-enriched air is used (hereinafter, the combustion-supporting gas is referred to as “oxygen” for convenience). The tips of the pulverized coal blowing pipe 2 and the outer pipe 3 are open, and both pipe ends are at substantially the same position in the longitudinal direction of the burner body. An oxygen inlet 30 is provided at the rear end of the outer tube 3.

The tip portion of the pulverized coal blowing tube 2 is a reduced diameter pipe portion 20 whose inner diameter is gradually reduced toward the pipe end side, and a pipe end portion connected to the reduced diameter pipe portion 20, and the inner diameter is the pipe end. It is comprised from the enlarged diameter pipe part 21 gradually expanded toward the side. Therefore, the inner diameter D ₁ of the end portion near the burner rear end of the reduced diameter tube portion 20 (= the end portion of the equal diameter tube portion 22 closer to the burner rear end side than the reduced diameter tube portion 20), and the reduced diameter tube portion 20 end of the burner tip closer to the inner diameter D ₂ of the (= burners near the rear end of the end portion of the radially enlarged tube part 21), the inner diameter D ₃ of the tip portion of the radially enlarged tube portion 21 (= the tube end), D _1> The relationship of D ₂ , D ₃ > D ₂ is satisfied.

The spread angle θ of the inner surface of the expanded diameter pipe portion 21 with respect to the tube axis (the angle formed by the extended surface of the inner surface of the expanded diameter tube portion 21 and the tube axis) is less than 10 °. In the pulverized coal blowing burner of the present invention, after the pulverized coal flow (pulverized coal + carrier gas) conveyed in the pulverized coal blowing tube 2 is compressed in the burner axial direction in the reduced diameter pipe portion 20, the expanded diameter pipe portion. 21. A pulverized coal flow having a dispersed flux cross-section along the inner surface of the expanded diameter pipe portion 21 is formed by being suddenly released from the compressed state in 21, and this dispersed pulverized coal flow blows out from the burner tip. As a result, the contact efficiency between the pulverized coal and oxygen fed from the outer pipe 3 and further oxygen in the hot air is increased. However, when the spread angle θ of the inner surface of the expanded diameter pipe portion is 10 ° or more, the dispersibility of the pulverized coal flow from the tip of the burner is deteriorated.
In addition, the lower limit of the spread angle θ of the inner surface of the expanded diameter pipe portion 21 is not particularly limited, but in order to obtain a desired effect by abruptly opening the pulverized coal flow in the expanded diameter pipe portion 21, it is set to 5 ° or more. It is preferable to do. Moreover, the particularly preferable range of the spread angle θ is 6 ° to 9 ° in terms of dispersibility of the pulverized coal flow.

The inner diameter D ₂ of the same burner tip inboard end to the inner diameter D ₁ of the burner near the rear end edge portion of the reduced tube portion 20 preferably satisfies the following formula (1).
0.6 ≦ D ₂ / D ₁ ≦ 0.8 (1)
Here, if D ₂ / D ₁ exceeds 0.8, the tendency of the dispersibility of the pulverized coal flow to decrease increases, whereas if D ₂ / D ₁ is less than 0.6, the diameter of the reduced diameter pipe portion 20 is reduced. Since the degree of is too large, problems such as an increase in pressure loss in the burner and clogging of pulverized coal at the position of the reduced diameter pipe portion may become apparent.

The inside diameter D ₁ and the inner diameter D ₃ of the radially enlarged tube tip of the burner near the rear end edge portion of the reduced tube portion 20, it is preferable to satisfy the following expression (2).
_{D 1 / D 3 ≦ 1.0 ...} (2)
Here, if D ₁ / D ₃ exceeds 1.0, the flow rate of the pulverized coal flow at the tip of the burner increases, so the residence time of the pulverized coal at the burner tip is shortened, and the combustibility of the pulverized coal tends to decrease. is there. In the case of the pulverized coal blowing pipe 2 having a constant outer diameter (equal diameter) through the equal diameter pipe section 22 to the larger diameter pipe section 21, the pipe wall thickness at the tip of the larger diameter pipe section 21 is minimized, and D _A state where ₃ is substantially equal to the outer diameter of the pulverized coal blowing pipe 2 is a substantial lower limit of D ₁ / D ₃ .

There is no particular restriction length L ₂ is a length L ₁ and reduced tube portion 20 of the enlarged diameter pipe portion 21, the length L ₁ of the radially enlarged tube portion 21 with respect to the diameter of the pulverized coal injection pipe 2 If the length is too short, the effect of the present invention due to the provision of the diameter-expanded tube portion 21 cannot be sufficiently obtained. On the other hand, if the length is too long, the structural connection with the outer tube 3 becomes a problem. in relation to the inner diameter D ₁ of the burner rear end edge portion, it is preferable that the length that satisfies _{0.1D 1 ≦ L 1 ≦ D 1} . Also, easily disturbed in the pulverized coal flow since the too short length L ₂ of the reduced tube portion 20 is squeezed angle of the reduced-diameter pipe portion becomes steep, which may adversely affect the dispersibility of the pulverized coal flow is there. In addition, wear of the reduced diameter pipe portion is also accelerated. Therefore, the length L ₂ of the reduced diameter pipe portion 20 is set to a length that satisfies 0.1D ₁ ≦ L ₂ in relation to the inner diameter D _{1 of the} end portion near the burner rear end of the reduced diameter pipe portion 20. It is preferable.

2, 5 is a tuyere, 6 is a blow pipe for blowing hot air connected to the tuyere 5, and the pulverized coal blowing burner A shown in FIG. However, the tip side portion is disposed so as to be located in the tip side portion or tuyere 5 of the blow pipe 6.
In addition, although the inner diameter of the diameter-reduced tube portion 20 and the diameter-expanded tube portion 21 of the present embodiment is both tapered, these inner surfaces are not necessarily tapered, for example, in the tube axis direction. It may be configured in an arc shape or include an arc-shaped portion, or may be a combination of a plurality of tapered surfaces having different taper angles in the tube axis direction.

  In the pulverized coal blowing burner A of the present embodiment, pulverized coal accompanying the carrier gas is introduced into the pulverized coal blowing tube 2, and this pulverized coal enters the tuyere 5 or the blow pipe 6 from the tip of the pulverized coal blowing tube 2. It is blown and introduced into the furnace while burning. Further, oxygen (pure oxygen is preferable to oxygen-enriched air from the viewpoint of combustion rate) is supplied to the outer pipe 3 (flow path 4), and the pulverized coal blown out from the tip of the pulverized coal blowing pipe 2 is supplied. Oxygen is supplied to the surroundings. Here, the pulverized coal flow (pulverized coal + carrier gas) transported in the pulverized coal blowing pipe 2 is compressed in the burner axial direction in the diameter-reduced pipe portion 20, and then rapidly increases from the compressed state in the diameter-expanded pipe portion 21. Released. As a result, a pulverized coal flow having a dispersed flux cross section along the inner surface of the enlarged diameter pipe portion 21 is formed, and the dispersed pulverized coal flow is blown out from the tip of the pulverized coal blowing pipe 2. Therefore, oxygen blown out from the tip of the outer tube 3 (flow path 4) reliably collides with the dispersion-strengthened pulverized coal flow, and mixing (contact) of the pulverized coal and oxygen is efficiently performed. . For this reason, oxygen is effectively utilized for combustion of pulverized coal, and the combustion rate of pulverized coal is effectively improved. Further, even after the oxygen is consumed, the contact efficiency between the pulverized coal flow and the oxygen in the hot air is improved, and the combustibility of the pulverized coal is also improved.

  The results of experiments conducted to identify the structure of the pulverized coal blowing pipe 2 are shown in FIGS. An outline of the apparatus used in the experiment is shown in FIG. In this experimental apparatus, the pulverized coal cut out together with the carrier gas from the pulverized coal hopper was supplied to the burner, the pulverized coal flow blown from the tip of the burner was photographed with a video camera, and the spread angle was measured. In this experiment, the pulverized coal supply amount was set to be equivalent to 200 kg / t.

FIG. 4 shows the influence of the spread angle θ of the inner surface of the enlarged diameter pipe portion 21 on the spread angle of the pulverized coal flow at the burner tip (spread angle with respect to the burner tube axis of the pulverized coal flow blown from the burner tip). . This test was performed under the following conditions. The burner tip speed is the speed of the pulverized coal flow at the tip of the burner (hereinafter the same).
Burner tip speed: 16.5m / s
D ₂ / D ₁ : 0.7
_{D 1} / D 3: 1.0
According to FIG. 4, until the spread angle θ of the inner surface of the expanded pipe portion 21 is about 7 °, the spread angle of the pulverized coal flow increases as the spread angle θ increases, but when the spread angle θ exceeds 7 °, Conversely, the spread angle of the pulverized coal flow becomes smaller. This is considered to be because when the spread angle θ increases to some extent, the pulverized coal flow cannot follow the spread of the inner surface of the enlarged diameter pipe portion and peels from the inner surface of the enlarged diameter pipe portion.

FIG. 5 shows the effect of the burner tip speed of the pulverized coal flow on the spread angle of the pulverized coal flow. This test was performed under the following conditions.
Burner tip speed: 3 levels of 8.2 m / s, 16.5 m / s, 24.7 m / s Spreading angle θ of the inner surface of the expanded diameter pipe portion: 7 ° to 10 °
D ₂ / D ₁ : 0.7
_{D 1} / D 3: 1.0

According to FIG. 5, the smaller the burner tip speed of the pulverized coal flow, the larger the spread angle of the pulverized coal flow tends to be increased. However, when the spread angle θ of the inner surface of the expanded pipe portion is increased to 10 °, There is a tendency for the spread angle of the coal flow to decrease.
From the results of FIG. 4 and FIG. 5 described above, it has been found that the spread angle θ of the inner surface of the diameter-expanded tube portion 21 is less than 10 °, preferably 5 ° to less than 10 °, and particularly preferably 6 ° to 9 °. .

FIG. 6 shows the effect of the narrowing angle α of the inner surface of the reduced diameter pipe portion 20 (the narrowing angle α of the inner surface of the reduced diameter pipe portion with respect to the burner tube axis) on the spread angle of the pulverized coal flow. This test was performed under the following conditions.
Burner tip speed: 2 levels of 8.2 m / s and 16.5 m / s Spreading angle θ of the inner surface of the expanded pipe portion: 7 °
D ₂ / D ₁ : 0.7
_{D 1} / D 3: 1.0
According to FIG. 6, when the narrowing angle α of the inner surface of the reduced diameter pipe portion 20 increases, the spread angle of the pulverized coal flow tends to decrease. Therefore, if D ₂ / D ₁ is the same, the narrowing angle α of the inner surface of the reduced diameter pipe portion is preferably as small as possible, and is also preferable from the viewpoint of suppressing wear of the reduced diameter pipe portion 20 due to the pulverized coal flow.

FIG. 7 shows the influence of the ratio D ₂ / D ₁ between the inner diameter D ₂ near the burner front end and the inner diameter D ₁ near the burner rear end of the reduced diameter pipe portion 20 on the spread angle of the pulverized coal flow. Yes. This test was performed under the following conditions.
Burner tip speed: 2 levels of 8.2 m / s and 16.5 m / s Spreading angle θ of the inner surface of the expanded pipe portion: 7 °
_{D 1} / D 3: 1.0
According to FIG. 7, the spread angle of the pulverized coal flow tends to decrease as D ₂ / D ₁ increases. From the viewpoint of ensuring the spread angle of the pulverized coal flow, D ₂ / D ₁ ≦ 0. It can be seen that about 8 is preferable.

Next, other embodiments of the pulverized coal blowing burner of the present invention will be described.
FIGS. 8 to 13 show other embodiments of the pulverized coal blowing burner of the present invention, and show a longitudinal section of the burner body.
The pulverized coal blowing burner of the present invention may have a structure having an equal-diameter pipe portion 23 having a constant inner diameter between the reduced diameter pipe portion 20 and the enlarged diameter pipe portion 21 of the pulverized coal injection pipe 2 as shown in FIG. Good.
Further, the pulverized coal blowing burner of the present invention only needs to satisfy the above-mentioned conditions for the inner surface of the pulverized coal blowing tube 2, and therefore the pulverized coal blowing tube 2 does not have a straight outer surface as shown in FIG. May be. That is, in this embodiment, the tube wall of the tip side portion of the pulverized coal blowing tube 2 is configured to have an equal thickness, and therefore the outer diameters of the reduced diameter pipe portion 20 and the enlarged diameter pipe portion 21 change according to the respective inner diameters. is doing.

In the embodiment of FIG. 10, the structure of the burner body is a concentric double tube structure similar to that of FIG. 1, but the cooling fluid is supplied to the outer tube 3a (the flow path 4a between the outer tube 3a and the inner tube 2). A cooling fluid inlet 30a is provided at the rear end of the outer tube 3a. The tip of the burner is easily melted by heat generated by the combustion of pulverized coal or radiant heat from red coke in the raceway. By adopting a structure (cooling structure) provided with the cooling fluid channel 4a as described above, In addition, it is possible to effectively suppress melting of the burner tip.
In the pulverized coal blowing burner of such an embodiment, the contact efficiency between the pulverized coal flow and the oxygen in the hot air is effectively increased by blowing the pulverized coal flow from the burner tip in a dispersed state. A cooling fluid such as air is supplied to the flow path 4a between the pulverized coal blowing pipe 2 and the outer pipe 3a, and the tip of the pulverized coal blowing burner (particularly, the tip of the pulverized coal blowing pipe 2) is cooled. Is done.

In the embodiment of FIG. 11, the burner body has a concentric triple tube structure. An outermost tube 7 is further provided outside the outer tube 3 in the embodiment of FIG. 1, and this outermost tube 7 (outermost tube 7 8 is a cooling fluid supply pipe, and a cooling fluid inlet 70 is provided at the rear end of the outermost pipe 7. The configuration of the pulverized coal blowing pipe 2 (inner pipe) and the outer pipe 3 which is an oxygen blowing pipe is the same as that of the embodiment of FIG.
In the pulverized coal blowing burner of such an embodiment, since the pulverized coal flow is blown out in a dispersed state from the tip of the pulverized coal blowing tube 2, the oxygen blown from the tip of the outer tube 3 reliably collides with the pulverized coal flow. Thus, mixing (contact) of pulverized coal and oxygen is efficiently performed. For this reason, oxygen is effectively utilized for combustion of pulverized coal, and the combustion rate of pulverized coal is effectively improved. Moreover, even after the oxygen is consumed, the contact efficiency between the pulverized coal flow and the oxygen in the hot air is improved, and the combustibility of the pulverized coal is also improved. Further, a cooling fluid such as air is supplied to the flow path 8 between the outer tube 3 and the outermost tube 7, and the tip of the pulverized coal blowing burner is cooled.

In the pulverized coal blowing burner according to the present invention, the pulverized coal blowing tube 2 can also have a single tube structure provided with a flow path for cooling fluid inside the tube wall. FIG. 12 shows one embodiment, and a cooling fluid channel 9 is provided inside the tube wall of the pulverized coal blowing tube 2, and a cooling fluid such as cooling water supplied into the channel 9. As a result, the pulverized coal blowing pipe 2 is cooled. The flow path 9 is provided with a supply part (not shown) for supplying a cooling fluid from outside the pipe and a discharge part (not shown) for discharging the cooling fluid flowing through the flow path 9 to the outside of the pipe. It is done.
Further, when the burner body has a double-pipe structure composed of the inner pipe 2 and the outer pipe 3, or a triple-pipe structure having an outermost pipe 7 on the outer side, the limit for obtaining the effect of the present invention. The difference between the lengths of the outer tube 3 and the inner tube 2 (in the case of a double tube structure) or the lengths of the outermost tube 7, the outer tube 3 and the inner tube 2 (in the case of a triple tube structure), respectively. May be attached.

Further, when the pulverized coal blowing pipe 2 has a single pipe structure provided with the flow path 9 for the cooling fluid, only the tip portion thereof can be formed as a single pipe structure without the flow path for the cooling fluid. FIG. 13 shows an embodiment thereof, and the pulverized coal blowing pipe 2 does not include a tubular body portion 2a having a flow path 9 for cooling fluid and a flow path for cooling fluid connected to the end thereof. The tubular body portion 2b and a tubular body portion 2c which is not provided with a cooling fluid flow path connected as the most advanced portion ahead of the tubular body portion 2b. The tubular body portion 2c is connected to the reduced diameter tubular portion 20 and the expanded diameter tube. Part 21. Note that this preferred configuration of the radially reduced tube 20 and the radially enlarged tube portion 21 of the tube part _{2c (D 1 ~D 3, L} 1, L 2 of the relationship, etc.) are as previously described, also, the tube The body part 2c can also have a structure as shown in the embodiment of FIGS.
In this way, the tip of the pulverized coal blowing pipe 2 has a single pipe structure that does not include a flow path for the cooling fluid. By reducing the blowing pipe tip width (diameter), the downstream side (the flow direction of hot air) This is because the strong turbulent flow region generated on the downstream side of the substrate is reduced, and adhesion / growth of foreign matter can be suppressed.
The tip of the pulverized coal blowing pipe not provided with the cooling fluid flow path is composed of the pipe part 2b and the pipe part 2c because the tip part (pipe part 2c) is melted or foreign matter is This is for facilitating replacement of the tip when it adheres.

  The tip of the pulverized coal blowing pipe (tube portion 2b, tube portion 2c) that does not have a cooling fluid flow path may be straight, but the pulverized coal is placed in the axial direction of the blow pipe or in a direction close thereto. In order to make it eject, you may make it curve with a suitable curvature in a longitudinal direction like this embodiment. In this case, either one of the tube part 2b or the tube part 2c may be curved, or both may be curved. In the present embodiment, the tube portion 2b is curved with an appropriate curvature in the longitudinal direction. In general, the pulverized coal blowing burner A provided with the pulverized coal blowing tube 2 is disposed obliquely through the blow pipe as shown in FIG. There is a possibility that the pulverized coal collides with the inner surface of the blow pipe or tuyere and wears them. On the other hand, by curving the tip portion of the pulverized coal blowing pipe (tube portion 2b in this embodiment) with an appropriate curvature, the pulverized coal can be ejected in the axial direction of the blow pipe or in a direction close thereto, Wear on the inner surface of the blow pipe and tuyere can be suppressed.

  The embodiment of FIG. 14 relates to a pulverized coal blowing pipe having a single-pipe structure that does not have a reduced diameter pipe section and an expanded diameter pipe section. The pulverized coal blowing pipe 2 'is a pipe provided with a flow path 9' for cooling fluid. It is composed of a body part 2x and a tube part 2y not provided with a cooling fluid channel connected to the end of the body part 2x, and the tube part 2y is curved with an appropriate curvature in the longitudinal direction. The reason for bending the tubular portion 2y in this way is as described above.

Next, a method for blowing pulverized coal into the metallurgical furnace using the pulverized coal blowing burner of the present invention as described above will be described.
As shown in FIG. 2, the basic form of the pulverized coal blowing method according to the present invention is such that the tip side portion of the burner body of the pulverized coal blowing burner A is connected to the tuyere 5 of the metallurgical furnace or to this. The pulverized coal is inserted into the metallurgical furnace through the tuyere 5 from the burner A.
On the other hand, as a method for further improving the dispersibility of the pulverized coal, as shown in FIG. 15, the tip side portions of the burner bodies of the _two pulverized coal blowing burners A ₁ and A ₂ are placed on the tuyere of the metallurgical furnace or on this. The extension lines of the burner central axes x ₁ and x ₂ do not intersect each other in the continuous blow pipe (in this embodiment, the blow pipe), and both the burner central axes x ₁ and x ₂ are blow pipes. There is a method of inserting the pulverized coal into the metallurgical furnace through the tuyere from both the pulverized coal blowing burners A ₁ and A ₂ so as not to intersect the central axis.

According to this method, not only the dispersibility of pulverized coal is increased by using _two pulverized coal blowing burners A ₁ and A ₂ , but also both pulverized coal blowing burners A arranged asymmetrically as described above. _Since the pulverized coal flows from ₁ and A ₂ interfere with each other, the dispersibility of the pulverized coal flow is further enhanced, and the contact efficiency between the pulverized coal and the introduced oxygen, and further the oxygen in the hot air Can be further enhanced.
The pulverized coal blowing burner of the present invention and the pulverized coal blowing method using the same can be applied not only to a blast furnace but also to various metallurgical furnaces including a scrap melting furnace.

[Example 1]
In order to confirm the effect of the present invention, the following pulverized coal combustion test was conducted.
Using a small combustion test furnace of coke packed bed type, the combustion test of pulverized coal is performed in the test form shown in FIG. 16, the combustion rate η calculated from the carbon balance shown in the following equation (3) is obtained, and the combustion of pulverized coal Rate was evaluated.
η = {(Rac · Ccoke−Rpc · Ccoke) / (Rpc _inj · _Cpc )} × 100 (3)
Where Rac: Theoretical coke consumption determined from combustion gas conditions (kg / h)
Rpc: Coke input during pulverized coal injection (kg / h)
Rpc _inj : Amount of pulverized coal injection (kg / h)
Ccoke: Carbon content in coke (mass%)
Cpc: Carbon content in pulverized coal (mass%)

  In order to simulate the lower part of an actual blast furnace, the combustion test furnace has one tuyere and one blow pipe, and a pulverized coal blowing burner is inserted into the blow pipe through the tube wall. The blowing burner was installed so as to be inclined with respect to the blow pipe tube axis. The inner pipe of the pulverized coal blowing burner (pulverized coal blowing pipe) is connected to the pulverized coal hopper via the pulverized coal feed pipe, and the pulverized coal in the pulverized coal hopper is blown through the burner inner pipe together with the carrier gas. It is designed to be supplied inside. Further, the outer tube of the burner is connected to an air line so that a predetermined amount of oxygen or oxygen-enriched air is supplied.

  While blowing hot air at 1200 ° C through the blow pipe into the combustion test furnace, the pulverized coal is blown into the blow pipe from the burner, and the pulverized coal is burned in the combustion space in the blow pipe and the coke packed bed. It was. During the test, coke was appropriately charged in the combustion test furnace, and the coke packed bed level was kept constant.

The test results are shown in Table 1 and Table 2 together with each test condition.
In Table 1, Invention Examples 1 and 2 are examples using the pulverized coal blowing burner of the present invention having the double pipe structure shown in FIG. 1, and Invention Example 3 is a triple pipe structure shown in FIG. It is an example using the pulverized coal blowing burner of the present invention having the following.
On the other hand, Comparative Example 1 was an example using an ordinary single tube structure burner, and Comparative Example 2 was a conventional burner having a double tube structure in which the pulverized coal blowing tube did not have a reduced diameter tube portion and an expanded diameter tube portion. In Example and Comparative Example 3, the pulverized coal blowing pipe has a double pipe structure having a reduced diameter pipe part and an enlarged diameter pipe part, but a burner having a spread angle θ on the inner surface of the enlarged diameter pipe part exceeding the range of the present invention was used. It is an example.

According to Table 1, Examples 1 to 3 of the present invention have a combustion rate of pulverized coal of 7 to 8% compared to Comparative Example 1, 4 to 5% compared to Comparative Example 2, and compared to Comparative Example 3. 3-4%. In addition, the invention example 3 used a burner having a triple pipe structure, and the cooling air was supplied from the outermost pipe. Therefore, the melt resistance of the burner was further improved as compared with the example 1 of the invention.
The examples in Table 2 are for examining the influence of D ₁ / D ₃ , and all use the pulverized coal blowing burner of the present invention having the double pipe structure shown in FIG. In all of Examples 4 to 6 of the present invention, a high pulverized coal combustion rate is obtained.

[Example 2]
Internal volume 2828M ^3, in blast furnace wings talkative 32, Dezukuhi 2.2t ^/ m 3 ^/ day, in terms of the pulverized coal ratio 180 kg / t, was a series of operations as follows.
In operation using a conventional burner, two conventional pulverized coal blowing burners were inserted into each tuyere in the form shown in FIG. 15, and pulverized coal was blown using these pulverized coal blowing burners. Next, at a certain time, the pulverized coal-injection burner at each tuyere was replaced with that of the example of the present invention, and the operation was continued. The pulverized coal blowing burner of the example of the present invention has a form as shown in FIG. 13, and the spread angle θ of the expanded pipe portion of the tube portion 2 c is 7 °, D ₂ / D ₁ : 0. 7, D ₁ / D ₃ : 1.0 was used. Two of these pulverized coal blowing burners were inserted into each tuyere in the form shown in FIG. 15, and pulverized coal was blown using these pulverized coal blowing burners.

  In FIG. 17, the transition of the ventilation pressure in the said blast furnace operation is shown. As shown in the figure, during operation using the conventional burner before switching to the pulverized coal blowing burner of the example of the present invention, the blowing pressure is about 333 kPa, but to the pulverized coal blowing burner of the example of the present invention. After switching, the blast pressure gradually decreased and finally changed to about 323 kPa. This is because the amount of unburned char accumulated in the furnace core is reduced by switching to the pulverized coal injection burner of the present invention, and the pressure loss in the furnace is about 133 kPa under the top pressure of about 200 kPa. This is considered to be because the air permeability in the furnace was improved. Moreover, when the discharge amount of unburned char was measured by microscopic observation of the furnace top dust, the discharge amount of unburned char was reduced after switching to the pulverized coal blowing burner of the example of the present invention. This is considered to be because the combustion rate of pulverized coal was improved by switching to the pulverized coal blowing burner of the present invention example, and the amount of unburned char was reduced.

  The pulverized coal blowing burner of the present invention and the pulverized coal blowing method using the same can be used when a large amount of pulverized coal is blown into the furnace from the tuyere in various metallurgical furnaces including a blast furnace and a scrap melting furnace. it can.

The longitudinal cross-sectional view which shows one Embodiment of the pulverized coal blowing burner of this invention Longitudinal section of the blast furnace tuyere with the pulverized coal blowing burner of FIG. Explanatory drawing which shows typically the test equipment used in the test of Drawing 4-Drawing 7 A graph showing the effect of the spread angle θ of the inner surface of the expanded pipe portion of the pulverized coal blowing pipe on the spread angle of the pulverized coal flow at the tip of the burner Graph showing the effect of the pulverized coal flow velocity at the burner tip on the spread angle of the pulverized coal flow at the burner tip A graph showing the effect of the narrowing angle α of the inner surface of the reduced diameter pipe portion of the pulverized coal blowing pipe on the spread angle of the pulverized coal flow at the tip of the burner A graph showing the influence of the ratio D ₂ / D ₁ between the inner diameter D _{2 of the} end near the burner tip of the reduced diameter pipe portion and the inner diameter D ₁ of the end near the burner rear end on the spread angle of the pulverized coal flow at the tip of the burner The longitudinal cross-sectional view which shows the pulverized coal blowing pipe | tube tip part in other embodiment of the pulverized coal blowing burner of this invention The longitudinal cross-sectional view which shows the pulverized coal blowing pipe | tube tip part in other embodiment of the pulverized coal blowing burner of this invention The longitudinal cross-sectional view which shows other embodiment of the pulverized-coal blowing burner of this invention The longitudinal cross-sectional view which shows other embodiment of the pulverized-coal blowing burner of this invention The longitudinal cross-sectional view which shows the pulverized coal blowing pipe | tube tip part in other embodiment of the pulverized coal blowing burner of this invention The longitudinal cross-sectional view which shows the pulverized coal blowing pipe | tube tip part in other embodiment of the pulverized coal blowing burner of this invention The longitudinal cross-sectional view which shows the pulverized-coal-injection pipe front-end | tip part in one Embodiment of the pulverized-coal-injection burner provided with the pulverized-coal-injection pipe of the single pipe | tube structure which does not have a reduced diameter pipe part and an enlarged diameter pipe part FIG. 1 shows an embodiment of a pulverized coal blowing method using the pulverized coal blowing burner of the present invention, (a) is a plan view showing the arrangement of the pulverized coal blowing burner in the blow pipe, and (b) is also a front view. Figure Explanatory drawing which shows the test equipment used in the Example of this invention The graph which shows the transition of ventilation pressure about Example 2 which performed operation using the conventional type pulverized coal injection burner, and then switched to the pulverized coal injection burner of the example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Burner main body 2 Pulverized coal blow-in pipe 2a, 2b, 2c Tube part 3, 3a Outer pipe 4, 4a Flow path 5 Tuyere 6 Blow pipe 7 Outermost pipe 8 Flow path 9 Flow path 20 Reduced diameter pipe part 21 Diameter expansion Pipe part 22 Equal-diameter pipe part 23 Equi-diameter pipe part A, A ₁ , A ₂ Pulverized coal blowing burner x ₁ , x ₂ Burner central axis

Claims (10)

In the pulverized coal blowing burner for blowing pulverized coal into the metallurgical furnace through the tuyere,
The tip side portion of the pulverized coal blowing pipe constituting the burner main body is a reduced diameter pipe portion whose inner diameter is gradually reduced toward the pipe end side, and a pipe end portion connected to the reduced diameter pipe portion, the inner diameter of the pipe A pulverized coal-injection burner for a metallurgical furnace, comprising a diameter-expanded pipe portion that gradually increases in diameter toward the end, and having a spread angle θ with respect to the pipe axis of the inner diameter of the diameter-expanded pipe portion being less than 10 °.   2. The pulverized coal blowing burner for metallurgical furnace according to claim 1, wherein a divergence angle θ of the inner surface of the expanded diameter pipe portion with respect to the tube axis is 5 ° or more and less than 10 °.   The pulverized coal blowing burner for a metallurgical furnace according to claim 1 or 2, wherein an equal-diameter tube portion having a constant inner diameter is provided between the reduced-diameter tube portion and the expanded-diameter tube portion. Of claims 1 to 3, the inner diameter D ₂ of the burner tip inboard end of the inner diameter D ₁ and the reduced tube of the burner near the rear end edge portion of the reduced tube portion and satisfies the following formula (1) The pulverized coal blowing burner for a metallurgical furnace according to any one of the above.
0.6 ≦ D ₂ / D ₁ ≦ 0.8 (1) The inner diameter D ₁ and the radially enlarged tube inner diameter D ₃ of the tip of the burner near the rear end edge portion of the reduced tube portion according to claim 1, characterized by satisfying the following formula (2) Pulverized coal blowing burner for metallurgical furnaces.
D ₁ / D ₃ ≦ 1.0 (2)   The burner body has a double pipe structure composed of an inner pipe and an outer pipe, the inner pipe constitutes a pulverized coal blowing pipe, and the outer pipe constitutes a combustion-supporting gas blowing pipe. The pulverized coal blowing burner for metallurgical furnaces according to any one of claims 1 to 5.   The burner main body has a double pipe structure composed of an inner pipe and an outer pipe, the inner pipe constitutes a pulverized coal blowing pipe, and the outer pipe constitutes a flow path for cooling fluid. The pulverized coal blowing burner for metallurgical furnaces according to any one of claims 1 to 5.   The pulverized coal blowing burner for a metallurgical furnace according to any one of claims 1 to 6, wherein the pulverized coal blowing tube has a structure including a flow path for cooling fluid inside the tube wall.   The burner body has a triple pipe structure consisting of an inner pipe, an outer pipe, and an outermost pipe, the inner pipe constitutes a pulverized coal blowing pipe, and the outer pipe constitutes a combustion supporting gas blowing pipe, The pulverized coal blowing burner for a metallurgical furnace according to any one of claims 1 to 5, wherein the outermost pipe constitutes a flow path for a cooling fluid. A method for blowing pulverized coal into a metallurgical furnace using the pulverized coal blowing burner according to any one of claims 1 to 9,
Inserting the tip side of the burner body of the pulverized coal blowing burner into the tuyere of the metallurgical furnace or a blow pipe connected thereto, and blowing the pulverized coal into the metallurgical furnace through the tuyere A pulverized coal injection method into a metallurgical furnace.

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