Tuyere of blast furnace and blast furnace operation method

Abstract

To provide a tuyere of a blast furnace and a blast furnace operation method using the tuyere, the tuyere being equipped with a pulverized coal blowing lance and a hydrogen-based reducing gas blowing lance, in which adhesion of pulverized coal to the inner surface of the tuyere is further suppressed and blockage can be prevented.SOLUTION: A tuyere of the blast furnace comprises a pulverized coal blowing lance for blowing pulverized coal into the tuyere and a hydrogen-based reducing gas blowing lance for blowing a hydrogen-based reducing gas into the tuyere. The tip of the pulverized coal blowing lance is located at a position 50 mm-100 mm from the tip of the tuyere, the tip of the hydrogen-based reducing gas blowing lance is located at a position 60 mm-120 mm from the tip of the tuyere, and the tip of the pulverized coal blowing lance is located further inside the furnace of the blast furnace than the tip of the hydrogen-based reducing gas blowing lance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a blast furnace tuyere and a method for operating a blast furnace. [Background technology]

[0002] Conventionally, in blast furnace operation, pulverized coal, which is cheaper than lump coke, is injected through a copper tuyeres to reduce the amount of lump coke used. Furthermore, in order to reduce the reducing agent rate of the blast furnace and reduce the amount of CO2 emissions, operations in which a gaseous reducing agent containing hydrogen is injected through the tuyeres are being considered.

[0003] As an operating method for injecting pulverized coal and a gaseous reducing agent from a tuyere, for example, the method of Patent Document 1 has been proposed. Patent Document 1 describes that the inlet of the lance for injecting the gaseous reducing agent is located 0 to 50 mm from the tip of the tuyere. It also discloses that the inlet of the lance for injecting the solid reducing agent for injecting the pulverized coal is located upstream of the inlet of the lance for injecting the gaseous reducing agent in the air blowing direction, and that the inlet of the lance for injecting the solid reducing agent is located within a range of 200 mm from the tip of the tuyere. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4997734 Summary of the Invention [Problem to be solved by the invention]

[0005] The method of Patent Document 1 claims that by setting the position for injecting the gaseous reducing agent or solid reducing agent at an appropriate position, it is possible to suppress pressure loss in the tuyere or blowpipe, thereby enabling the gaseous reducing agent or solid reducing agent to be effectively used without reducing the reduction efficiency.

[0006] However, in the method of Patent Document 1, pulverized coal, which is a solid reducing agent, may adhere and accumulate on the inner surface of the tuyere.

[0007] Therefore, the present invention aims to provide a blast furnace tuyere and a blast furnace operation method using the tuyere, which are equipped with a pulverized coal injection lance and a hydrogen-based reducing gas injection lance, and which can further suppress adhesion of pulverized coal to the inner surface of the tuyere and prevent blockage. [Means for solving the problem]

[0008] The present invention has been made to solve the above problems, and the gist of the invention is as follows.

[0009] (1) A tuyere of a blast furnace comprising a pulverized coal injection lance for injecting pulverized coal into the tuyere, and a hydrogen-based reducing gas injection lance for injecting a hydrogen-based reducing gas into the tuyere, The tip of the pulverized coal injection lance is located 50 mm to 100 mm from the tip of the tuyere, The tip of the hydrogen-based reducing gas injection lance is located 60 mm to 120 mm from the tip of the tuyere, A tuyere of a blast furnace, characterized in that a tip of the pulverized coal injection lance is located on the inner side of the blast furnace than a tip of the hydrogen-based reducing gas injection lance.

[0010] (2) The tuyere of a blast furnace according to (1) above, characterized in that the hydrogen-based reducing gas injection lance is incorporated in the tuyere.

[0011] (3) The tuyere of a blast furnace according to (2) above, characterized in that a tip of the hydrogen-based reducing gas injection lance is disposed at a position on the inner surface of the tuyere.

[0012] (4) The tuyere of a blast furnace according to (1) above, characterized in that a tip of the pulverized coal injection lance is located at a position of 50 mm to 80 mm from a tip of the tuyere.

[0013] (5) Injecting pulverized coal into the tuyere from a position 50 mm to 100 mm from the tip of the tuyere using a pulverized coal injection lance; A hydrogen-based reducing gas is injected into the tuyere from a position of 60 mm to 120 mm from the tip of the tuyere using a hydrogen-based reducing gas injection lance; A method for operating a blast furnace, characterized in that the position into which pulverized coal is injected is on the inner side of the blast furnace relative to the position into which a hydrogen-based reducing gas is injected.

[0014] (6) The method for operating a blast furnace according to (5) above, characterized in that the hydrogen-based reducing gas injection lance is incorporated in the tuyere.

[0015] (7) The method for operating a blast furnace according to (6) above, characterized in that a tip of the hydrogen-based reducing gas injection lance is disposed at a position on the inner surface of the tuyere.

[0016] (8) A method for operating a blast furnace according to (6) or (7) above, characterized in that a hydrogen-based reducing gas heated to a temperature above room temperature is injected from the hydrogen-based reducing gas injection lance incorporated in the tuyere.

[0017] (9) The method for operating a blast furnace according to (5) above, characterized in that pulverized coal is injected from the pulverized coal injection lance at a position 50 mm to 80 mm from the tip of the tuyere.

[0018] (10) A method for operating a blast furnace according to the above (5), characterized in that pulverized coal is injected at a rate of 70 kg / t-pig or more. Effect of the Invention

[0019] According to the present invention, in a tuyere equipped with a pulverized coal injection lance and a hydrogen-based reducing gas injection lance, and a method for operating a blast furnace using the tuyere, it is possible to provide a blast furnace tuyere and a method for operating a blast furnace that can further suppress adhesion of pulverized coal to the inner surface of the tuyere and prevent blockage. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a diagram showing the configuration of a tuyere of a blast furnace according to an embodiment. [Diagram 2]FIG. 2 is a diagram showing an example of the positional relationship between a pulverized coal injection lance and a hydrogen-based reducing gas injection lance. [Diagram 3] FIG. 2 is a diagram showing an outline of an experimental furnace according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The tuyere and operation method of the blast furnace of this embodiment will be described. This embodiment relates to a tuyere of a blast furnace in which a hydrogen-based reducing gas and pulverized coal are blown into the tuyere and then blown into the blast furnace together with hot air, and a method of operating the blast furnace using the tuyere.

[0022] In this embodiment, a numerical range expressed using "to" means a numerical range that includes the numerical values ​​before and after "to" as the lower limit and upper limit.

[0023] Fig. 1 is a configuration diagram showing the configuration of a blast furnace tuyere 1 of this embodiment. Fig. 1 shows a vertical cross-sectional structure along the blowing direction of the tuyere 1. The tuyere 1 is equipped with a pulverized coal injection lance 2 and a hydrogen-based reducing gas injection lance 4.

[0024] The tuyere 1 is installed penetrating the side wall of the blast furnace to blow hot air into the blast furnace, and is connected to a blowpipe 6. The blowpipe 6 supplies hot air generated in the hot stove to the tuyere 1, and the hot air is blown from the tuyere 1 into the blast furnace.

[0025] The pulverized coal injection lance 2 is a lance that injects pulverized coal into the tuyere 1. The pulverized coal injection lance 2 has a tip 2a, which is an injection port, disposed in the tuyere 1. The pulverized coal injection lance 2 is inserted through the blowpipe 6 and disposed in the tuyere 1. The material of the pulverized coal injection lance 2 is not particularly limited, but may be appropriately selected from known heat-resistant materials used for lances in blast furnaces, such as SUS310.

[0026] The hydrogen-based reducing gas injection lance 4 is a lance that injects a hydrogen-based reducing gas into the tuyere 1. The hydrogen-based reducing gas injection lance 4 has a tip 4a, which is an injection port, disposed in the tuyere 1. The hydrogen-based reducing gas injection lance 4 can be inserted through the blowpipe 6 and disposed in the tuyere 1. It is also preferable that the hydrogen-based reducing gas injection lance 4 is inserted through the tuyere 1 and incorporated in the tuyere 1. The material of the hydrogen-based reducing gas injection lance 4 is not particularly limited, and may be appropriately selected from known heat-resistant materials used for lances in blast furnaces, such as SUS310.

[0027] The hydrogen-based reducing gas injected from the hydrogen-based reducing gas injection lance 4 is not limited to pure hydrogen gas composed of hydrogen alone, but also includes hydrogen-based gas containing hydrogen as a main component. For example, the hydrogen-based reducing gas may be a mixed gas containing 70 mol % or more of hydrogen gas and carbon monoxide, etc., produced by reforming natural gas.

[0028] The arrangement of the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 will be further explained. When pulverized coal and hydrogen-based reducing gas are injected simultaneously, the hydrogen-based reducing gas starts to burn first. As a result, the ambient temperature rises, accelerating the thermal decomposition of the pulverized coal. The ash that remains undecomposed travels into the furnace on the carrier gas, but the ambient temperature may exceed the melting point of the ash. In that case, the ash travels to the furnace in a semi-molten state. When the ash collides with the water-cooled inner surface of the tuyere, it is cooled and accumulates in the tuyere. If this phenomenon continues, the ash will pile up on the inner surface of the tuyere, causing the blast pressure to rise and making the operation unstable. There is also concern that increased accumulation may lead to clogging of the tuyere.

[0029] In contrast, it has been found that by arranging the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 as described below, adhesion of pulverized coal to the tuyere 1 can be effectively suppressed when operating in which pulverized coal and hydrogen-based reducing gas are injected into the tuyere 1.

[0030] First, in this embodiment, the tip 2a (pulverized coal injection position) which is the injection port of the pulverized coal injection lance 2 is located inside the blast furnace, relative to the tip 4a (hydrogen-based reducing gas injection position) which is the injection port of the hydrogen-based reducing gas injection lance 4. In other words, the tip 4a of the hydrogen-based reducing gas injection lance 4 is located outside the blast furnace, relative to the tip 2a of the pulverized coal injection lance 2. As shown in FIG. 1, the inside of the furnace is the side closer to the inside of the blast furnace, and is the downstream side in the blowing direction by the tuyere 1. The outside of the furnace is the side farther from the blast furnace, and is the upstream side in the blowing direction.

[0031] Since the tip 2a is located inside the furnace more than the tip 4a, the hydrogen-based reducing gas burns upstream of the pulverized coal injection position, and the pulverized coal is appropriately heated by the combustion. This allows the tip 2a of the pulverized coal injection lance 2 to be positioned inside the tuyere furnace more than in the conventional case. This makes it possible to avoid the collision of the pulverized coal with the tuyere 1 and suppress adhesion, so that clogging of the tuyere 1 can be more effectively prevented.

[0032] Next, the position of the tip of each lance in this embodiment is shown by the distance from the tuyere tip 1a to the tip of each lance. The distance is the distance from the intersection (position of the tuyere tip) of a straight line 1L passing through the tuyere tip 1a and the tuyere central axis L to the intersection (tip of the lance) of a straight line 2L or a straight line 4L passing through each lance tip and the tuyere central axis L. The straight line 1L is a straight line passing through the point located on the innermost side of the tuyere 1 and perpendicular to the tuyere central axis L. The straight line 2L is a straight line passing through the tip 2a of the pulverized coal injection lance 2 and perpendicular to the tuyere central axis L. The straight line 4L is a straight line passing through the tip 4a of the hydrogen-based reducing gas injection lance 4 and perpendicular to the tuyere central axis L.

[0033] The tip 2a of the pulverized coal injection lance 2 is located at a distance A of 50 mm to 100 mm from the tuyere tip 1a to the tip 2a. If the distance A is within this range, clogging of the inside of the tuyere 1 due to adhesion of pulverized coal can be effectively suppressed, and the generation of dust discharged from the blast furnace can be suppressed.

[0034] If the distance A is less than 50 mm, the pulverized coal will fly out of the raceway in front of the tuyere before it leaves the pulverized coal injection lance 2 and completes combustion, which is undesirable because it increases the amount of dust. Therefore, the distance A is set to 50 mm or more.

[0035] If the distance A exceeds 100 mm, the injected pulverized coal is likely to collide with the inner wall surface of the tuyere, promoting adhesion and making the tuyere 1 more susceptible to clogging. Therefore, the distance A is set to 100 mm or less.

[0036] Moreover, it is preferable that the tip 2a of the pulverized coal injection lance 2 is located at a position where the distance A is 50 mm to 80 mm. When the distance A is within this range, accumulation of pulverized coal in the tuyere 1 can be further reliably suppressed, and generation of dust can also be suppressed.

[0037] Next, the tip 4a of the hydrogen-based reducing gas injection lance 4 is located at a position where the distance B from the tuyere tip 1a to the tip 4a is 60 mm to 120 mm.

[0038] If the distance B is less than 60 mm, the pulverized coal injected from a position closer to the furnace interior may not be sufficiently heated. If the distance B is 60 mm or more, the pulverized coal can be sufficiently heated.

[0039] If the distance B exceeds 120 mm, the tip 4a of the hydrogen-based reducing gas injection lance 4 becomes far from the tip 1a of the tuyere, and the combustion field of the hydrogen-based reducing gas in the tuyere 1 becomes wide. Then, the atmospheric temperature due to the combustion of the hydrogen-based reducing gas increases, and there is a possibility that the tuyere 1 and the blowpipe 6 may be melted. Therefore, the distance B is set to 120 mm or less.

[0040] Other positional relationships between the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 will be described. First, when the tuyere 1 is viewed from the direction of the tuyere central axis L, that is, in a cross section perpendicular to the tuyere central axis L, the positional relationship between the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 is not particularly limited, and they may be disposed in any position. The positional relationship between the lances indicates the direction in which the pulverized coal or hydrogen-based reducing gas is injected from each lance within the tuyere 1.

[0041] 2(a) to (c) show examples of the positional relationship between the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 other than that shown in FIG. 1. In FIG. 2(a), the positional relationship between the lances when viewed from the direction of the central axis L of the tuyere is also shown.

[0042] As shown in FIG. 1, they may be arranged in a positional relationship in which they face each other at the top and bottom positions in the tuyere 1, or they may be arranged in a positional relationship in which they face each other at the left and right positions. They do not have to be arranged in a positional relationship in which they face each other. For example, as shown in FIG. 2(a), the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 may be arranged in a positional relationship of 90° when viewed from the direction of the tuyere central axis L. They can be in any position between an opposing positional relationship (the angle between the lances is 180°) and a positional relationship on the same side (the angle between the lances is 0°). In addition, the injection direction of both or one of the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 may be directed in a direction parallel to the tuyere central axis L.

[0043] Moreover, the hydrogen-based reducing gas injection lance 4 is preferably disposed in a state of being incorporated into the tuyere 1 as shown in Fig. 2(b) or (c). "Incorporated into the tuyere 1" means that the hydrogen-based reducing gas injection lance 4 is disposed in a state of being inserted into the wall of the tuyere 1.

[0044] When the hydrogen-based reducing gas injection lance 4 is to be incorporated into the tuyere 1, for example, a hole through which the lance passes is formed in advance when the tuyere 1 is cast. The lance can then be inserted into the hole of the cast tuyere 1 to incorporate it into the tuyere 1. The tip 4a of the hydrogen-based reducing gas injection lance 4, which is the injection position, may be located near the inner surface of the tuyere, or may protrude into the tuyere beyond the position of the inner surface.

[0045] When the hydrogen-based reducing gas injection lance 4 is incorporated into the tuyere 1, the lance can also be cooled by the cooling water in the tuyere 1. Normally, the tuyere 1 is cooled by the cooling water flowing inside. When the hydrogen-based reducing gas injection lance 4 is incorporated into the tuyere 1, the lance is disposed near the flow path. Therefore, by incorporating the lance into the tuyere 1, the hydrogen-based reducing gas injection lance 4 can also be cooled.

[0046] This makes it possible to protect the hydrogen-based reducing gas injection lance 4 from heat, for example, even when the temperature of the hydrogen-based reducing gas is high. Therefore, if the hydrogen-based reducing gas injection lance 4 is made of a material having an appropriate heat resistance, the lance will not deform due to heat, and heated hydrogen-based reducing gas can be continuously supplied to the blast furnace.

[0047] Furthermore, when the hydrogen-based reducing gas injection lance 4 is incorporated into the tuyere 1, the tip 4a is positioned on the inner surface of the tuyere 1, thereby making it possible to make the distance between the tip 2a of the pulverized coal injection lance 2 and the tip 4a of the hydrogen-based reducing gas injection lance 4 as large as possible within the tuyere 1. Furthermore, in this case, it is preferable to position the tip 2a of the pulverized coal injection lance 2 opposite the tip 4a as shown in Fig. 2(b), since this makes it possible to make the distance between the lance tips even larger.

[0048] If the tip 4a of the hydrogen-based reducing gas injection lance 4 is located outside the furnace relative to the tip 2a of the pulverized coal injection lance 2, the pulverized coal is heated by the combustion of the hydrogen-based reducing gas. On the other hand, if the tips of the lances are close to each other, the pulverized coal is not only heated by the combustion of hydrogen but also its combustion is promoted. If the combustion of the pulverized coal becomes excessive, it is likely to melt and adhere to the tuyere. Therefore, by positioning the tip 4a on the inner surface of the tuyere and by appropriately separating the tips of the lances, the combustion and melting of the pulverized coal can be suppressed, while the pulverized coal can be heated to an appropriate temperature range by the combustion of the hydrogen-based reducing gas.

[0049] It should be noted that the pulverized coal injection lance 2 does not need to be incorporated into the tuyere 1. The pulverized coal injection lance 2 is subject to wear due to friction with solid pulverized coal, and therefore requires more frequent replacement. Therefore, it needs to be easily replaceable, but if it is incorporated into the tuyere 1, replacement of the lance becomes difficult. Therefore, the pulverized coal injection lance 2 does not need to be incorporated into the tuyere 1, but may be disposed in the tuyere via an appropriate position of the blowpipe 6.

[0050] Next, a method of operating a blast furnace using the tuyere 1 of the present embodiment will be described. In the method of operating a blast furnace, pulverized coal is injected into the tuyere 1 with the pulverized coal injection lance 2 from a position 50 mm to 100 mm from the tip of the tuyere 1, and a hydrogen-based reducing gas is injected into the tuyere 1 with the hydrogen-based reducing gas injection lance 4 from a position 60 mm to 120 mm from the tip of the tuyere 1. The position where the pulverized coal is injected is closer to the inside of the blast furnace than the position where the hydrogen-based reducing gas is injected.

[0051] In the blast furnace operation method of this embodiment, the amount of pulverized coal injected from the pulverized coal injection lance 2 can be 70 kg / t-pig or more. In an operation of injecting pulverized coal, when 70 kg / t-pig or more is injected, the pulverized coal is likely to accumulate significantly. However, if pulverized coal and hydrogen-based reducing gas are injected at the above-mentioned injection position, the accumulation of pulverized coal can be more reliably suppressed even when 70 kg / t-pig or more of pulverized coal is injected. The upper limit is not particularly limited, but in consideration of an operation in which both pulverized coal and hydrogen-based reducing gas are simultaneously injected into a blast furnace, it may be, for example, 200 kg / t-pig or less.

[0052] The temperature of the hydrogen-based reducing gas is not particularly limited, and may be about room temperature or may be a heated temperature. When injecting hydrogen-based reducing gas heated to a temperature exceeding room temperature, it is preferable to inject it from the hydrogen-based reducing gas injection lance 4 incorporated in the tuyere 1. Even if the hydrogen-based reducing gas is heated, the hydrogen-based reducing gas injection lance 4 incorporated in the tuyere 1 is cooled by the cooling water of the tuyere 1, and is therefore protected from the heat of the gas. This prevents the lance from being damaged by heat, and allows the injection of the heated hydrogen-based reducing gas to continue. The upper limit of the temperature of the hydrogen-based reducing gas is not particularly limited, but may be less than 1200°C in consideration of the heat resistance temperature of the steel pipe that can be used as the lance. The injection amount of the hydrogen-based reducing gas may be set as appropriate, but may be set to, for example, 50 to 1000 Nm 3 It can be / t-pig.

[0053] According to the blast furnace tuyere 1 and blast furnace operation method of the above embodiment, in an operation in which pulverized coal and hydrogen-based reducing gas are injected into the tuyere 1 from their respective lances, adhesion of pulverized coal to the inner surface of the tuyere can be more effectively suppressed, and tuyere blockage can be more reliably prevented. EXAMPLES

[0054] A more detailed description will be given with reference to an example. An operational test was carried out with the pulverized coal injection lance 2 and the hydrogen-based reducing gas injection lance 4 arranged in the specified manner shown in the embodiment, and the accumulation of pulverized coal was confirmed.

[0055] (Experimental Method) Using an experimental furnace 20 (test equipment) simulating the lower part of a blast furnace shown in FIG. 3, a combustion test was carried out under the test conditions shown in Table 1 below while changing the positions at which hydrogen-based reducing gas and pulverized coal were injected. Here, experiments were also carried out under pulverized coal injection conditions of more than 70 kg / t-pig (100, 150, 200 kg / t-pig). However, since it is obvious that the frequency of adhesion increases and tuyere blockage becomes more likely as the injection amount increases, the condition with the smallest injection amount was shown. As the hydrogen-based reducing gas, hydrogen gas was injected at room temperature. Combustion was continued for 6 hours for one test condition (lance arrangement). The experimental furnace 20 is filled with coke. The experimental furnace 20 is a vertical rectangular furnace with a length of 1.2 m, a width of 1.2 m, and a height of 2.4 m, and has a fireproof brick lining on the inner surface of the steel shell. In the experimental furnace 20 of FIG. 3, the tuyere, each lance, etc. are also indicated with the same reference numerals as in the embodiment.

[0056] [Table 1]

[0057] (Method of evaluating adhesion status) After combustion under each test condition, the adhesion (accumulation) state of pulverized coal on the tuyere 1 was evaluated by the following method. The adhesion was confirmed through a sight window 10 arranged at the rear of the blowpipe 6. The extent of the area of ​​the adhesion occupying the circular opening of the tuyere 1 as viewed through the sight window 10 was then observed and compared with conditions simulating the prior art (prior example in Table 2 below) as a standard. Specifically, in the prior example, the area of ​​the adhesion occupying the opening area of ​​the tuyere 1 was 50%, which was used as the standard. Cases where 50% or more was clogged were evaluated as "x", cases where less than 50% but 20% or more was clogged were evaluated as "○", and cases where less than 20% was clogged were evaluated as "◎".

[0058] (Dust generation) Regarding dust generation, after the combustion test of each test example, the presence or absence of dust collected from the exhaust gas was confirmed and evaluated. If dust was confirmed, it was rated as "present", and if no dust was present, it was rated as "absent".

[0059] The injection positions of each lance (distances A and B from the tip of the tuyere to the tip of each lance) and the above evaluation results for the Prior Art, Working Example, and Comparative Example are shown in Table 2. As described above, the results in Table 2 are for a pulverized coal injection rate of 70 kg / t-pig, which is the rate at which adhesion to the tuyere is least likely to occur, but the results of the tuyere clogging and dust generation were similar even under injection conditions where the amount of pulverized coal was increased to 200 kg / t-pig.

[0060] [Table 2]

[0061] In the prior example, the tip of the hydrogen-based reducing gas injection lance is located inside the furnace relative to the tip of the pulverized coal injection lance, which is the opposite arrangement to that in the embodiment. In the prior example, clogging occurred significantly.

[0062] When the pulverized coal injection position was located on the inside of the furnace from the hydrogen-based reducing gas injection position, almost no clogging of the tuyere was observed in Example 1 where the pulverized coal injection position was 50 mm and in Example 2 where it was 80 mm. In Example 3 where the pulverized coal injection position was 100 mm, adhesion of pulverized coal was confirmed, but it was confirmed that the adhesion was less than in the preceding example.

[0063] In Comparative Example 3, in which the pulverized coal injection position was 110 mm, the injection position of the hydrogen-based reducing gas was within the range shown in the embodiment, but the pulverized coal injection position was over 100 mm, resulting in 50% or more blockage. In Comparative Example 4, in which the pulverized coal injection position was 150 mm, blockage occurred to the same extent as in the preceding example. In Comparative Example 5, in which each injection position was within the range shown in the embodiment, but the hydrogen-based reducing gas injection position was on the furnace side (opposite to the examples), blockage of 50% or more also occurred.

[0064] In Comparative Example 1, where the pulverized coal injection position was 40 mm, no tuyere clogging occurred, but dust generation increased significantly. In Comparative Example 2, where the pulverized coal injection position was the same as in Comparative Example 1, the injection position of the hydrogen-based reducing gas was within the range shown in the embodiment, but dust generation was also confirmed.

[0065] In addition, in Comparative Example 4, where the hydrogen-based reducing gas injection position exceeded 120 mm, the temperatures of the tuyere and blowpipe rose. This is thought to be because the distance from the tuyere tip to the lance tip became longer, widening the hydrogen combustion field, resulting in a significant increase in the atmospheric temperature.

[0066] From the above, by setting the distance from the tuyere tip to the tip of the pulverized coal injection lance at 50mm to 100mm, the distance from the tuyere tip to the tip of the hydrogen-based reducing gas injection lance at 60mm to 120mm, and setting the pulverized coal injection position on the inside of the furnace relative to the hydrogen-based reducing gas injection position, good results were obtained in which tuyere blockage was effectively suppressed and dust generation was also prevented. [Explanation of symbols]

[0067] 1 Tuyere 2. Pulverized coal injection lance 4 Hydrogen-based reducing gas injection lance 6 Blowpipe

Claims

1. A tuyere of a blast furnace comprising a pulverized coal injection lance for injecting pulverized coal into the tuyere and a hydrogen-based reducing gas injection lance for injecting a hydrogen-based reducing gas into the tuyere, The tip of the pulverized coal injection lance is located 50 mm to 100 mm from the tip of the tuyere, The tip of the hydrogen-based reducing gas injection lance is located at a position of 60 mm to 120 mm from the tip of the tuyere, A tuyere of a blast furnace, characterized in that a tip of the pulverized coal injection lance is located on the inner side of the blast furnace than a tip of the hydrogen-based reducing gas injection lance.

2. The tuyere of a blast furnace according to claim 1, characterized in that the hydrogen-based reducing gas injection lance is incorporated in the tuyere.

3. 3. The tuyere of a blast furnace according to claim 2, wherein a tip of the hydrogen-based reducing gas injection lance is disposed at a position on an inner surface of the tuyere.

4. 2. The tuyere of a blast furnace according to claim 1, wherein the tip of the pulverized coal injection lance is located at a position of 50 mm to 80 mm from the tip of the tuyere.

5. Inject pulverized coal into the tuyere from a position 50 mm to 100 mm from the tip of the tuyere using a pulverized coal injection lance; A hydrogen-based reducing gas is injected into the tuyere from a position 60 mm to 120 mm from the tip of the tuyere using a hydrogen-based reducing gas injection lance; A method for operating a blast furnace, characterized in that the position into which pulverized coal is injected is on the inner side of the blast furnace relative to the position into which a hydrogen-based reducing gas is injected.

6. The method for operating a blast furnace according to claim 5, characterized in that the hydrogen-based reducing gas injection lance is incorporated in the tuyere.

7. 7. The method for operating a blast furnace according to claim 6, wherein a tip of the hydrogen-based reducing gas injection lance is disposed at a position on the inner surface of the tuyere.

8. 8. The method for operating a blast furnace according to claim 6 or 7, characterized in that a hydrogen-based reducing gas heated to a temperature higher than room temperature is injected from the hydrogen-based reducing gas injection lance incorporated in the tuyere.

9. The method for operating a blast furnace according to claim 5, characterized in that the pulverized coal is injected from a position 50 mm to 80 mm from the tip of the tuyere by the pulverized coal injection lance.

10. The method for operating a blast furnace according to claim 5, characterized in that pulverized coal is injected at 70 kg / t-pig or more.

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