JP4915074B2 - Apparatus for injecting reducing material into a blast furnace, and blast furnace operating method using the apparatus - Google Patents

Description

  The present invention relates to a reducing material blowing apparatus for blowing at least a gaseous reducing material from a blast furnace tuyere and a blast furnace operating method using the apparatus.

In blast furnace operation, as a substitute for expensive coke, low-cost and combustible fuel (pulverized coal, petroleum, naphtha, etc.) is generally blown from the tuyere, especially fuel gas such as natural gas. The following are known to be blown from the mouth.
(1) Even if pulverized coal is injected at 170 kg / t or more, a blast furnace operating method for the purpose of ensuring the combustibility, keeping the replacement rate with coke high, and maintaining the production amount and the fuel ratio, A blast furnace operating method characterized in that fuel gas is blown in front of a pulverized coal blowing position (see Patent Document 1).
(2) A blast furnace operating method whose main purpose is to realize a large amount of synthetic resin injection, in which auxiliary fuel such as natural gas is injected from an auxiliary fuel injection nozzle installed in a ventilation branch of a tuyere, A blast furnace operating method characterized in that synthetic resin particles are blown from a nozzle installed on the upstream side of blowing air from the auxiliary fuel blowing position (see Patent Document 2).

Also, regarding pulverized coal injection operation, a method for determining the optimum lance position that can prevent the pulverized coal injection lance from being melted without increasing the thermal load at the bottom of the blast furnace even if a large amount of pulverized coal is injected. Has been proposed.
This lance position determination method is a method of allowing the lance for blowing pulverized coal to penetrate the wall of the blow pipe for hot air blowing connected to the blast furnace tuyere and to pierce the tip of the lance into the blow pipe. A lance position determination method for blowing pulverized coal in a method in which pulverized coal blown from a lance is blown from a blast furnace tuyere together with hot air flowing in the blow pipe, the lance from the boundary position between the blast furnace tuyere and the blow pipe. The gist of the present invention is to determine the position of the lance so that the distance (hereinafter sometimes referred to as lance position) L (mm) to the tip of the lance satisfies the following formula (1) (Patent Document) 3).
0.22 × [PCR] + 48.2 ≦ L ≦ 1017.3−1.33 × [PCR] −14.7 × [VM] --------- (1)
However, [PCR]: Amount of pulverized coal injection (kg / pig iron t)
[VM]: Volatile content in pulverized coal (%)
JP-A-4-268003 JP 2000-178614 A JP-A-8-134518

When a gas reducing material such as natural gas is blown from the tuyere, the city gas blown from the lance burns instantly. For this reason, the highest temperature position in the raceway in the blast furnace (hereinafter simply referred to as the “highest temperature position in the furnace”) is shifted to the furnace wall side than when only pulverized coal is injected, and the blast furnace wall There is a problem that the temperature increases and heat loss from the furnace wall increases.
Usually, when the temperature of the furnace wall rises, the cooling of the furnace wall will be strengthened, but if so, the thermal efficiency will decrease. The city gas injection is performed for the purpose of operation with a low reductant ratio, but it is difficult to realize the operation with a low reductant ratio unless the problem of the blast furnace wall temperature rise is solved.

In this regard, in Patent Documents 1 and 2, although the blowing of a gas reducing material such as natural gas is performed, the relative position between the pulverized coal blowing lance or the synthetic resin blowing lance and the gas reducing material blowing lance There is no mention of the maximum temperature position in the furnace.
On the other hand, in Patent Document 3, consideration is given to the maximum temperature position in the furnace, but in Patent Document 3, only consideration is given to pulverized coal injection, and nothing is mentioned about injection of the gas reducing material. Not.

As described above, no conventional solution has been made to the problem of the blast furnace furnace wall temperature rise due to the shift of the furnace maximum temperature position by blowing the gas reducing material from the tuyere.
The present invention has been made to solve such a problem, and when a gas reducing material is blown from a tuyere, a reducing material blowing device and a blast furnace operating method capable of suppressing a temperature rise of a blast furnace furnace wall are obtained. It is aimed.

In order to solve the above-mentioned problems, the inventor has examined how much the maximum temperature position in the furnace moves when city gas is injected, using a coke-filled test combustion furnace simulating a blast furnace. In addition, as the city gas, liquefied natural gas was used, which was added with liquefied propane gas for fuel increase, and the calorific value was controlled to 11000 ± 100 kal / m ³ .
As shown in FIG. 3, the coke-filled test combustion furnace 10 is a rectangular furnace having a furnace height of 1000 mm and a furnace depth of 600 mm, and has one tuyere 11 on the furnace wall 10a. A blow pipe 13 for blowing hot air is connected to the tuyere 11, and the blow pipe 13 is provided with an inlet side pressure gauge 15 for measuring the pressure in the blow pipe.
Further, a coke charging inlet 17 and an exhaust port 19 are provided in the upper part of the furnace, and an outlet pressure gauge 21 for measuring the pressure of the exhaust gas is provided at the exhaust port.
Further, the blow pipe 13 is provided with a lance for blowing a gas reducing material and a lance for blowing pulverized coal. In the coke filled test combustion furnace 10, the installation positions of the gas reducing material blowing lance and the pulverized coal blowing lance, and the tuyere 11 can be changed as appropriate.

  In the coke-filled test combustion furnace 10 configured as described above, hot air is blown from the tuyere 11 as well as the blast furnace, and pulverized coal and city gas as a gas reducing material are blown to burn the coke in the furnace. .

First, only pulverized coal was injected, and the gas temperature in the furnace at that time was measured. The result is shown in FIG. In FIG. 4, the horizontal axis represents the distance from the tuyere tip to the inside of the furnace, and the vertical axis represents the gas composition and gas temperature.
As shown in FIG. 4, it is understood that the maximum temperature position in the furnace is about 500 mm from the tip of the tuyere when the city gas is not injected.

  Next, the same experiment was conducted for the case where city gas was injected. The result is shown in FIG. City gas is highly combustible and burns immediately after being blown. Therefore, if the city gas blowing position is in the blow pipe, pressure loss occurs due to an increase in gas volume due to combustion of city gas. Therefore, the city gas injection position was set near the tip of the tuyere. Here, the pressure loss refers to the difference between the inlet pressure measured by the inlet pressure gauge 15 and the outlet pressure measured by the outlet pressure gauge 21.

As shown in FIG. 5, when city gas is injected, it can be seen that the maximum temperature position in the furnace is at a position of about 400 mm from the tip of the tuyere.
Comparing FIG. 4 and FIG. 5, it can be seen that the maximum temperature position in the furnace is shifted by about 100 mm to the outside of the furnace by blowing city gas. Since the maximum temperature position in the furnace is determined by the city gas injection position, when the city gas injection is performed, the maximum temperature position in the furnace is returned to the same position as in the case where the city gas injection is not performed. The city gas blowing position may be moved to the inside of the 100 mm furnace.
However, if only the city gas blowing lance is extended into the furnace beyond the tip of the tuyere, the lance will melt immediately.
In order to prevent this, the inventor can move the tip of the lance to the inside of the furnace while preventing the lance from being melted by increasing the length of the tuyere protruding into the furnace and installing the lance therein. And gained knowledge.

As described above, when city gas injection is performed, in order to solve the problem of blast furnace furnace wall temperature rise due to the shift of the maximum temperature position in the furnace to the inside of the furnace, the city gas injection position is What is necessary is just to move to the 100 mm furnace inside which is the said shift part by gas blowing.
The inventor further advanced the study and realized that it is desirable to move the maximum temperature position in the furnace further to the inside of the furnace than in the case of blowing only pulverized coal from the viewpoint of preventing the blast furnace furnace wall temperature from rising.
However, in order to move the maximum temperature position in the furnace further to the inside of the furnace, it is necessary to move the city gas blowing position to the inside of the furnace, and in this case, the tuyere further protrudes to the inside of the furnace. If the tuyere is further projected to the inside of the furnace, it is considered that the tuyere is worn due to the influence of the in-furnace material such as coke and slag. Therefore, the tuyere cannot be randomly projected inside the furnace.

Therefore, the inventor conducted the following operation test in order to investigate the effect of protruding the tuyere inside the furnace from the viewpoint of how the tuyere defect situation changes.
1) Test method (1) The number of tuyere shown in Table 1 shown in Table 1 with different projecting lengths in the furnace was prepared and installed in a blast furnace. The in-furnace protrusion length L refers to the distance from the blast furnace inner wall surface 31 to the tuyere inner tip 30a in a state where the tuyere 30 is installed in the blast furnace, as shown in FIG.

(2) Three months after installation, the tuyere was removed, and the upper tuyere defect length La and lower tuyere defect length Lb at the tip of the tuyere were measured as shown in FIG.
2) Test results
FIG. 8 is a graph showing the relationship between the tuyere protrusion length L and the tuyere defect lengths La and Lb. The horizontal axis represents the in-furnace protrusion length L, and the vertical axis represents the tuyere tip defect length. ing.
As shown in FIG. 8, when the in-furnace protrusion length L is increased, the tuyere lower defect length Lb hardly changes, whereas the tuyere upper defect length La is equal to the in-furnace protrusion length L. It has been found that when the thickness exceeds 600 mm, it increases rapidly.

The reason why the upper tuyere defect rapidly increases when the tuyere protrusion length L of the tuyere exceeds 600 mm is considered as follows.
There are two types of defects at the tip of the tuyere, which are caused by wear due to swirling of coke in the raceway portion and due to melting damage caused by dripping hot metal in the furnace. As long as the projecting length L into the furnace is short, wear due to the swirling of the coke occupies most, so the chip length at the top and bottom of the tuyere does not change significantly. However, when the protruding length L exceeds 600 mm, the upper part of the tuyere is affected by the dripping hot metal, and it is considered that the defect length is rapidly increased due to melting damage.

As shown in FIGS. 6 and 7, the tuyere is provided with a cooling pipe 33 therein, and cooling water flows in the pipe. For this reason, when the defect reaches the cooling pipe 33, the cooling pipe 33 is broken and water enters the furnace, so that the tuyere 30 can no longer be used. Therefore, the period until the defect reaches the cooling pipe 33 can be considered as the lifetime of the tuyere.
In view of this, if the tuyere protrusion length L exceeds 600 mm, the life of the tuyere is remarkably shortened, and at the same time, there is a risk that the cooling pipe 33 is damaged during operation and water enters the furnace. It shows that the nature becomes high.
Therefore, it can be said that the tuyere protruding length L is preferably 600 mm or less from the viewpoint of the life of the tuyere and the prevention of trouble in the furnace due to cooling pipe breakage.

The present invention has been made based on the above findings.
(1) A reducing material blowing device according to the present invention is a reducing material blowing device that blows at least a gaseous reducing material from a blast furnace tuyere, and a protrusion length from the inner wall surface of the blast furnace to the inside of the furnace is set to 350 mm to 600 mm. And a gas reducing material blowing port provided in the vicinity of the front end of the tuyere inside the furnace.
Note that the vicinity of the furnace inner tip of the blast furnace tuyere may cause pressure loss due to an increase in gas volume due to combustion of the gas reducing material blown from the gas reducing material blowing port in the tuyere or blow pipe. Says no position.

(2) A reducing material blowing device for blowing at least a gas reducing material from a blast furnace tuyere, wherein the tuyere has a protruding length from a blast furnace inner wall surface to the inside of the furnace of 350 mm to 400 mm, and the tuyere And a gas reducing material blowing port provided in the vicinity of the front end portion of the furnace.
By setting the tuyere protruding length from the inner wall of the blast furnace to the inner side of the furnace to 350 mm to 400 mm, the maximum temperature position in the furnace is on the furnace wall side even when a gas reducing material such as city gas is blown from the tuyere. Shifting can be prevented to suppress the temperature rise of the blast furnace wall, and the tip of the tuyere can be prevented as much as possible.

(3) Further, a reducing material blowing device for blowing at least a gas reducing material from a blast furnace tuyere, a tuyere whose protruding length from the inner wall surface of the blast furnace to the inside of the furnace is set to 350 mm to 600 mm, and a gas reducing material The lance for injecting the gas reducing material is provided, and the inlet of the lance for injecting the gas reducing material is arranged in the vicinity of the furnace inner end of the tuyere.

(4) A reducing material blowing device for blowing at least a gas reducing material from a blast furnace tuyere, a tuyere having a protruding length from the inner wall surface of the blast furnace to the inside of the furnace of 350 mm to 400 mm, and a gas reducing material The lance for injecting the gas reducing material is provided, and the inlet of the lance for injecting the gas reducing material is arranged in the vicinity of the furnace inner end of the tuyere.

(5) Further, in the above (3) or (4), the lance for blowing the gas reducing material is arranged in a range of 0 to 25 mm from the tip of the tuyere to the outside of the furnace. It is.

(6) Moreover, the blast furnace operating method which concerns on this invention blows a gas reducing material from this gas reducing material blowing device using the reducing material blowing device in any one of said (1)-(5). It is characterized by

  In the present invention, a tuyere whose projecting length from the inner wall surface of the blast furnace to the inside of the furnace is set to 350 mm to 600 mm, and a blowing port for the gas reducing material provided in the vicinity of the tip of the inside of the tuyere inside the furnace, As a result, even when a gas reducing material such as city gas is blown from the tuyere, the maximum temperature position in the furnace is prevented from shifting to the furnace wall side, and the maximum temperature position in the furnace is moved further inside the furnace. It is possible to suppress the temperature rise of the blast furnace wall without extremely shortening the life of the tuyere. As a result, operation with a low reducing material ratio by blowing city gas can be realized.

FIG. 1 is an explanatory view of a main part of a reducing material blowing device into a blast furnace according to the present embodiment.
The gas reducing material blowing device according to the present embodiment is a reducing material blowing device for blowing pulverized coal and a gas reducing material from a blast furnace tuyere, and a projection length L from the blast furnace inner wall surface 2 to the inside of the furnace is 400 mm. The gas reducing material blowing lance 5 for blowing city gas as the gas reducing material into the blow pipe 3 connected to the tuyere 1 and the pulverized coal as the solid reducing material The solid reducing material blowing lance 7 for blowing in is installed so that the two intersect.
The reason why the protrusion length L from the blast furnace inner wall surface 2 to the furnace inside at the tuyere is set to 400 mm is that the protrusion length L from the blast furnace inner wall surface 2 to the furnace inside at the normal tuyere is about 300 mm. This is because the protrusion length of the tuyere 1 into the furnace inside is increased by 100 mm, which is the shift amount of the maximum temperature position due to the city gas injection, so that the city gas injection position can be moved to the inside of the furnace 100 mm.

  The lance 5 for blowing the gas reducing material is inserted obliquely from the peripheral wall of the blow pipe 3 toward the center of the blow pipe 3, and is bent near the center of the blow pipe 3 in a direction parallel to the axis of the blow pipe 3. And the front-end | tip part 5a of the lance 5 for gas reducing material blowing is arrange | positioned in the same position as the tuyere inner side front-end | tip part 1a.

  The solid reducing material blowing lance 7 is inserted and installed obliquely from the peripheral wall of the blow pipe toward the center of the blow pipe 3 in the same manner as the gas reducing material blowing lance 5. The solid reducing material blowing port 7a located at the tip of the solid reducing material blowing lance 7 extends slightly inside the furnace from the crossing position with the gas reducing material blowing lance 5, and the gas reducing material The gas reducing material blowing port 5a located at the tip of the blowing lance 5 is disposed outside the furnace.

The rear end side of the gas reducing material blowing lance 5 is connected to a city gas supply pipe that supplies city gas. A city gas supply pipe receives a predetermined pressure and a predetermined amount of city gas from a city gas supply device (not shown). Supplied.
Further, the rear end side of the lance 7 for blowing the solid reducing material is connected to a pulverized coal airflow conveying pipe for airflowly conveying the pulverized coal produced by a pulverized coal producing apparatus (not shown).
The composition of the city gas used in this embodiment is 88.5% by volume of methane gas, 4.6% by volume of ethane gas, 5.4% by volume of propane gas, 1.5% by volume of butane gas, and the calorie is 11800 kcal / kg. Moreover, the brand of pulverized coal was Blackwater coal, and the one having 80% of fine particles that passed through a sieve having a mesh interval of 74 μm was used.

In the reducing material blowing device configured as described above, a predetermined amount of city gas is blown from the gas reducing material blowing lance 5 and a predetermined amount of pulverized coal is blown from the solid reducing material blowing lance 7. . The injected city gas and pulverized coal function as coke substitutes as reducing materials.
And in this Embodiment, the gas reducing material which is equipped with the tuyere 1 which the protrusion length L to the furnace inner side from the blast furnace inner wall surface 2 was set to 400 mm, and is located in the front-end | tip of the gas reducing material blowing lance 5 Since the blowing port 5a is arranged near the tip inside the tuyere furnace, the gas reducing material blowing port 5a located at the tip of the gas reducing material blowing lance 5 is arranged about 100 mm inside the furnace than usual. Therefore, the maximum temperature position in the furnace can be set to the same position as that of the normal pulverized coal injection alone.

As described above, in the present embodiment, the tuyere 1 in which the protruding length L from the blast furnace inner wall surface 2 to the inside of the furnace is set to 400 mm, which is about 100 mm longer than usual, is used, and the lance 5 for blowing the gas reducing material is used. Since the gas reducing material blowing port 5a located at the tip is arranged in the vicinity of the tip inside the tuyere furnace, the gas reducing material blowing port 5a located at the tip of the lance 5 for blowing the gas reducing material is about 100 mm than usual. It can be arranged inside the furnace, and the shift of the maximum temperature position in the furnace due to the city gas injection can be avoided.
Moreover, since the gas reducing material blowing port 5a located at the tip of the gas reducing material blowing lance 5 is arranged in the vicinity of the tip of the inside of the tuyere, the supplied city gas burns in the tuyere or the blow pipe. There is no problem of pressure loss due to an increase in gas volume generated when burning in a tuyere or a blow pipe. In addition, since the city gas is burned in the furnace, an excessive heat load is not applied to the cooling device that cools the surroundings of the tuyere 1 and the blow pipe 3, and heat loss is small.

Further, since the solid reducing material blowing lance 7 is arranged so as to intersect with the gas reducing material blowing lance 5, the pulverized coal ejected from the solid reducing material blowing lance 7 is the gas reducing material blowing lance. 5 is not sprayed directly, and wear of the gas reducing material blowing lance 5 can be prevented.
In addition, since the vicinity of the tip of the gas reducing material blowing lance 5 is bent so that the city gas blowing position becomes the tuyere center position, the city gas can be blown into the furnace evenly and stably. Operation is possible. In order to perform stable operation, it is preferable that the city gas injection position has a radius within one-sixth of the tuyere diameter from the central axis of the tuyere when the tuyere is circular.
If there is a bias in the city gas injection, the reduction reaction in the furnace will be biased, leading to a deterioration in the operating state such as an abnormal charge drop, resulting in a reduction in reduction efficiency.
Since the gas that passes through the lance 5 for blowing the gas reducing material is a gas, there is no fear of the tube being clogged or worn even if the lance for blowing the gas reducing material is bent.

  In the above-described embodiment, an example is shown in which a tuyere having a projection length L from the blast furnace inner wall surface 2 to the inside of the furnace of 400 mm is used. The projecting length L is for arranging the gas reducing material blowing lance 5 inside the furnace and does not necessarily have to be 400 mm, but projects by the shift of the maximum temperature position in the furnace due to the city gas blowing. It is sufficient if the length is increased. According to the inventor's consideration, since the shift amount of the maximum temperature position in the furnace due to the city gas injection is 50 to 100 mm, the protruding length of the tuyere is 50 to 100 mm longer than usual, and 350 to 400 mm. Any range is acceptable.

  However, in order to realize a low reducing agent ratio operation by moving the maximum temperature position in the furnace further to the inside of the furnace and further reducing the heat loss from the furnace wall, compared with the case of injection with pulverized coal alone, The protrusion length L of the tuyere may be further increased in the range of 600 mm or less from the blast furnace inner wall surface 2 to the furnace inner side. If the protrusion length L of the tuyere is in the range of 600 mm or less, as described in the section of [Means for Solving the Problems], the tuyere life can be practically used without being extremely shortened. Because.

In the above embodiment, an example in which the position of the gas reducing material blowing port 5a located at the tip of the gas reducing material blowing lance 5 is arranged at the same position as the tuyere inner tip 1a is shown. Since the position of the gas reducing material blowing port 5a located at the tip of the reducing material blowing lance 5 is essentially extended to the inside of the furnace by the shift of the maximum temperature position in the furnace due to the city gas blowing, When the length of the tuyere inside the furnace is longer than the shift, it is not always necessary to match the tuyere inside tip 1a.
However, the city gas blown from the lance 5 for blowing the gas reducing material needs to be in a position where pressure loss due to an increase in gas volume due to combustion in the blow pipe 3 or tuyere 1 does not occur. In terms of meaning, it is preferably arranged in the range of 0 to 25 mm from the tuyere furnace inner tip 1a to the furnace outer side.

In the above-described embodiment, city gas is taken as an example of the gas reducing material, but in addition, liquefied natural gas (LNG), liquefied petroleum gas (LPG), coke gas (COG), dimethyl ether (DME) ) Etc. may be used. Of course, a mixed gas of these gases can also be used.
In the above embodiment, pulverized coal is used as an example of the solid reducing material. However, in addition to the above, a pulverized synthetic resin, wood chip, or the like may be used.
Furthermore, in the above embodiment, an example in which both the gas reducing material and the solid reducing material are blown has been shown, but the same applies to the case where only the gas reducing material is blown.

In order to confirm the effect of the present invention, the maximum temperature position in the furnace of the embodiment shown in FIG. 1 was measured using a coke-filled test combustion furnace simulating the blast furnace shown in FIG. The result is shown in FIG.
As shown in FIG. 2, the maximum temperature position in the furnace is about 500 mm from the tip of the tuyere, which is the same as in the case where the city gas was not injected as shown in FIG. 4.
From this, the tuyere 1 in which the length L projecting from the blast furnace inner wall surface 2 to the inside of the furnace is set to 400 mm and the gas reducing material blowing port 5a positioned at the tip of the gas reducing material blowing lance 5 is provided. It was proved that a shift in the maximum temperature position in the furnace caused by blowing city gas could be avoided by placing it near the tip of the tuyere inside.

Also, instead of city gas, LNG (methane gas: 88.8% by volume, ethane gas: 5.6% by volume, propane gas: 3.7% by volume, butane gas: 1.8% by volume, calories: 11800kcal / kg), LPG (propane gas: 95.0% by volume, butane: 5.0% by volume, calories: 11100kcal / kg), COG (hydrogen: 58.5 vol%, CO gas: 6.4 vol%, CO ₂ gas: 2.0 vol%, methane: 27.4% by volume, ethylene gas: 2.6 vol%, N ₂ gas: 2.0% by volume, other calories: 4580kcal / Nm ³ ), DME was used to perform a test using the coke-filled test combustion furnace shown in FIG. It was almost the same as the result of city gas shown, and it was about 500mm from the tip of the tuyere. Therefore, even when various gases are used as the gas reducing material, the tuyere 1 with the projection length L set to 400 mm from the inner wall surface 2 of the blast furnace to the inside of the furnace is used and the gas reducing material is injected. It was proved that the shift of the maximum temperature position in the furnace due to the gas blowing can be avoided by arranging the gas reducing material blowing port 5a located at the tip of the lance 5 for use in the vicinity of the tip inside the tuyere furnace.

It is explanatory drawing of the reducing material blowing apparatus which concerns on one Embodiment of this invention. It is a graph which shows the verification result of one Embodiment of this invention. It is explanatory drawing of a test furnace. It is a graph which shows the maximum temperature position in a furnace when not blowing city gas. It is a graph which shows the maximum temperature position in a furnace at the time of performing city gas injection in a prior art example. It is explanatory drawing of the protrusion length L to the furnace of a tuyere. It is explanatory drawing of a tuyere defect | deletion. It is a graph which shows the relationship between tuyere protrusion length L and tuyere defect | deletion length La and Lb.

Explanation of symbols

    1 tuyere, 1a tuyere inner end, 3 blow pipe, 5 lance for blowing gas reducing material, 5a blowing port for gas reducing material, 7 lance for blowing solid reducing material, 7a blowing port for solid reducing material.

Claims (6)

A reducing material blowing device for blowing at least a gaseous reducing material from a blast furnace tuyere, a tuyere having a protruding length from the inner wall surface of the blast furnace to the inside of the furnace set to 350 mm to 600 mm, and a tip inside the furnace of the tuyere An apparatus for injecting a reducing material into a blast furnace, comprising a gas reducing material injection port provided in the vicinity. A reducing material blowing device for blowing at least a gaseous reducing material from a blast furnace tuyere, a tuyere having a protruding length from the inner wall surface of the blast furnace to the inside of the furnace set to 350 mm to 400 mm, and a tip inside the furnace of the tuyere An apparatus for injecting a reducing material into a blast furnace, comprising a gas reducing material injection port provided in the vicinity. A reductant blowing device that blows at least a gas reducing material from a blast furnace tuyere, a tuyere whose projecting length from the blast furnace inner wall surface to the inside of the furnace is set to 350 mm to 600 mm, and gas reduction that blows the gas reducing material An apparatus for injecting a reducing material into a blast furnace, comprising a lance for injecting material, wherein an insufflation port of the lance for injecting the gas reducing material is disposed in the vicinity of the inner end of the tuyere. A reductant blowing device that blows at least a gas reducing material from a blast furnace tuyere, a tuyere whose projecting length from the blast furnace inner wall surface to the inside of the furnace is set to 350 mm to 400 mm, and gas reduction that blows the gas reducing material An apparatus for injecting a reducing material into a blast furnace, comprising a lance for injecting material, wherein an insufflation port of the lance for injecting the gas reducing material is disposed in the vicinity of the inner end of the tuyere. The apparatus for injecting a reducing material into a blast furnace according to claim 3 or 4, wherein the injecting port of the lance for injecting the gas reducing material is arranged within a range of 0 to 25 mm from the tip of the tuyere to the outside of the furnace. A method for operating a blast furnace, characterized in that at least a gaseous reducing material is injected from the reducing material blowing device into the blast furnace using the reducing material blowing device into the blast furnace according to any one of claims 1 to 5. .

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