JPH0959704A - How to use carbonaceous material in blast furnace - Google Patents

Abstract

(57) [Abstract] SOLUTION: Powdered carbonaceous material is mixed into high temperature gas 5 generated by combustion of coke by hot air in front of tuyere 2 of the blast furnace, and is conveyed into the blast furnace by high temperature gas flow to obtain ore. Used for the reduction reaction of. For example, a method of mixing the powdery carbonaceous material into the high temperature gas through the powdery carbonaceous material supply nozzle 1 penetrating into the furnace from the outer surface of the furnace wall installed above the tuyere of the blast furnace may be adopted. [Effect] It is possible to reduce coke consumption and use low quality coke and ore.
Its economic value is extremely large compared to the conventional method of blowing carbonaceous material from the tuyere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of using carbonaceous material in a blast furnace, particularly to reduce the consumption of coke in the blast furnace and to expand the use of low quality coke and sinter. Regarding usage of carbonaceous material.

[0002]

2. Description of the Related Art Conventionally, in the operation of a blast furnace, in order to reduce the consumption of coke, injection of heavy oil from the tuyere, injection of tar, injection of natural gas, injection of carbonaceous material (pulverized coal, etc.), etc. Has been implemented. In particular, a blast furnace operation method in which carbonaceous material is blown in place of coke after the oil price rises has been studied and implemented.

For example, in Japanese Examined Patent Publication No. 60-43403, a pulverized coal having a particle size and a volatile content within a predetermined range is blown together with hot air from a tuyere, and the amount of hydrogen fed into the furnace is controlled within a predetermined range. A blast furnace operation method has been proposed which can control internal reaction and reduce fuel cost. In addition, Japanese Patent Publication No. 60-53083 and Japanese Patent Publication No. 60-53
No. 081 each discloses a method for improving the burning rate of powder fuel by inserting a burner for powder fuel injection into a blow pipe for blowing hot air at the tuyere of a blast furnace at a predetermined position, and a method for improving the burning rate of powder fuel. There is disclosed a method of avoiding ash adhesion by increasing the blowing speed to a predetermined speed or higher according to the progress of ash adhesion to the inner wall surface of the blow pipe.

In all of these conventional methods, a powdery carbonaceous material (for example, pulverized coal) is blown from the tuyere and burned with hot air. The carbonaceous material is used as fuel instead of coke. In this case, the amount of coke consumed can be reduced by the amount of powder carbonaceous material substituted. However, since the coke ratio is lowered, it is necessary to improve and improve the quality of coke and sinter. This is because stable operation cannot be achieved without improving the quality of both coke and sinter. However, if the quality is improved, the cost required for it will exceed the price difference between coke and alternative fuel (powdered carbonaceous material), and There were even cases where the economics of blowing tuyere on wood were questioned.

[0005]

DISCLOSURE OF THE INVENTION The present invention avoids the high quality of coke and sinter that is required when the carbonaceous material instead of coke is blown from the tuyere as described above and used.
It is another object of the present invention to provide a method of using carbonaceous material in a blast furnace that enables the use of even lower quality coke and sinter.

[0006]

[Means for Solving the Problems] The coke charged into the blast furnace together with iron ore and the like has a role as a fuel and a role as a reducing agent. Conventional carbon materials have been used as fuel, as is clear from the fact that they are blown from tuyere. However, when using carbonaceous material instead of coke, it is preferable to use it as a reducing agent as described later.

The present invention has been made on the basis of this premise, and the gist thereof lies in the following and the method of using the carbonaceous material.

Powder carbonaceous material is mixed in high temperature gas generated by combustion of coke by hot air in front of tuyere of the blast furnace, conveyed into the blast furnace by high temperature gas stream, and used as a reducing agent in the blast furnace. How to use carbonaceous materials in the characteristic blast furnace.

Charcoal in the blast furnace described above, characterized in that the powdered carbonaceous material is mixed into the high temperature gas through a nozzle penetrating into the furnace from the outer surface of the furnace wall installed above the tuyere of the blast furnace. How to use the material.

The reduction reaction in the blast furnace, in which the powdered carbonaceous material participates as a reducing agent, is a reduction reaction of iron oxide (FeO + C).
(→ Fe + CO), solution loss reaction with CO ₂ gas and H ₂ O gas (CO ₂ + C → 2CO, H ₂ O + C → CO + H ₂ ). CO ₂ gas that causes solution loss reaction, H ₂
Since O 2 gas is generally generated as a result of the gas reduction reaction of iron oxide, the solution loss reaction is also regarded as a reduction reaction. For example, CO ₂ gas is FeO + CO → Fe + CO
_It is produced by the reaction of ₂ , but when combined with the above-mentioned reaction of CO ₂ + C → 2CO, it becomes FeO + C → Fe + CO as a whole, which means that the reduction reaction of iron oxide with C occurs.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION How the above-mentioned problems are solved by the method of the present invention will be described below.

Table 1 shows the coke reaction load when powdered carbonaceous material was used as a fuel and when it was used as a reducing agent [Carburizing (C to pig iron to the total amount of coke used.
And the amount of coke consumed for the reduction]. That is, the total amount of carbonaceous material including coke necessary for producing 1t of pig iron in a blast furnace is approximately 500 kg, of which 350 k is used as fuel.
g, 150 kg of reducing agent and carburizing agent is consumed, and 200 kg of powdered carbonaceous material used is entirely used as fuel. Case 1, 150 kg of reducing agent and carburizing agent and the remaining 50 kg are used as fuel. Case 2 is the case.

As shown in Table 1, the coke reaction load is 50% in the case 1, whereas in the case 2 the coke reaction load is 50%.
At 0%, no coke was consumed in the reduction reaction.

In other words, when carbon dioxide is used to substitute the role of coke as fuel as in case 1, coke plays the role of reducing agent, and as will be described later, coke powder in the furnace Since coagulation is promoted, high quality coke that is not easily pulverized is required. On the contrary,
In case 2, since the carbonaceous material participates in the reduction reaction and the coke is not consumed in the reduction reaction, coke pulverization does not occur. That is, when considering the use of powdered carbonaceous material as a substitute for coke, it can be said that it is preferable to use it as a reducing agent.

As described above, in the conventional pulverized coal injection,
In order to increase the blowing amount, it was necessary to use high-quality coke, but in the method of the present invention, the role of coke as a reducing agent is replaced by carbonaceous material, so coke is consumed in the reduction reaction. No need to improve coke quality. Furthermore, it is possible to utilize low quality coke.

As described above, in order to use the powdery carbonaceous material as the reducing agent, it is necessary to reliably send the powdery carbonaceous material charged into the furnace to the part which can function as the reducing agent instead of the coke.

The part that can function as a reducing agent is the fusion layer of the blast furnace. Therefore, in the method of the present invention, as described above, the powdered carbonaceous material is mixed in the high temperature gas generated by the combustion of the coke by the hot air in front of the tuyere of the blast furnace, and is conveyed into the blast furnace by the high temperature gas stream (the above-mentioned. invention).

As a concrete measure for that, a nozzle (a powdery carbonaceous material supply nozzle) penetrating from the outer surface of the furnace wall into the furnace is installed above the tuyere, and the powdery carbonaceous material is blown into the furnace through the nozzle, The carbonaceous material is mixed with the high temperature gas generated in front of the tuyere and placed on the high temperature gas stream (the above invention).

FIG. 1 is a diagram for explaining the method of the present invention.
It is a schematic diagram of a powder carbonaceous material supply nozzle attachment part vicinity.
In the figure, 2 is a tuyere, and a combustion space called a so-called raceway 8 is formed in front of the tuyere.
Is a high temperature gas that is generated by the combustion of coke by hot air in the raceway 8 and then exits from there. Reference numeral 1 denotes a powdery carbonaceous material supply nozzle that penetrates into the furnace from the outer surface of the furnace wall installed above the tuyere. The powdery carbonaceous material 3 is blown into the furnace through the nozzle 1 and mixed into the high temperature gas 5. The powdery carbonaceous material 3 charged into the furnace is conveyed into the blast furnace together with the high temperature gas 5,
After reaching the fusion layer 6, it participates in the reduction reaction of the iron ore.
The portion (7) shown in the figure represents a coke filling layer.

The powdery carbonaceous material is mixed with the high temperature gas flow generated in front of the tuyere, and the air flow is carried into the blast furnace.
This high-temperature gas is a gas containing CO, H ₂ , and N ₂ as main components, which is generated when coke is burned by hot air, and does not burn carbonaceous material and gasify it, and always forms a fusion layer. Because it will pass. In addition, the powdery carbonaceous material is used as the carbonaceous material because if it is in a powdery state, it easily flows along with the air flow, and almost 100% is trapped in the ore layer in the softened state in the fusion layer (trap).
Because it is done.

Therefore, the portion where the powdery carbonaceous material is mixed in the high temperature gas is an appropriate portion between the tuyere and the fusion layer,
Just above the raceway is preferred. As described above, the powdered carbonaceous material is charged into this portion by installing a nozzle penetrating the inside of the furnace from the outer surface of the furnace wall in the upper part of the tuyere and blowing the powdered carbonaceous material through the nozzle. Can be achieved.

It is desirable that the particle size of the powdery carbonaceous material is sufficiently small so that the powdery carbonaceous material can be conveyed together with the high temperature gas stream and can pass through the gap between the coke packed layers existing between the tuyere and the fusion layer.

In the vicinity of the fusion layer, a so-called direct reduction reaction (hereinafter simply referred to as "reduction reaction") in which ore (sintered ore, pellet, ore ore) is reduced by C occurs, and powdery carbonaceous material is generated. Consumed. Since the powdery carbonaceous material has a small particle size, its reactivity is extremely higher than that of coke, and therefore, if the powdery carbonaceous material is present at this site, it is preferentially consumed in the reduction reaction. If no powdery carbonaceous material is used, or if it is blown from the tuyere even if it is used, the coke is consumed in the reduction reaction, but this reaction markedly reduces the strength of the coke. As described above, the coke pulverization in the furnace is promoted.

As described above, according to the method of the present invention, the consumption of coke due to the reduction reaction is suppressed, so that the strength of the coke does not decrease and it becomes possible to use coke of lower quality than before. Further, as described above, the reactivity of the powdery carbonaceous material is extremely higher than that of the coke, and the reduction of the ore (sintered ore, pellets, agglomerated ores) is promoted, and the ore's reducibility is low. However, the problem of return delay does not occur. That is, according to the method of the present invention, the coke consumption can be reduced by the amount replaced by the powdery carbonaceous material, and the quality constraint of the coke and the ore is greatly relaxed as compared with the case of the conventional pulverized coal injection. can do.

As shown in Table 1, although the amount of the powdery carbonaceous material that can be used in the method of the present invention is limited, if the powdery carbonaceous material is used in an amount more than that required as the reducing agent, The method of the present invention and the conventional method of blowing from the tuyere may be used in combination.
Even in this case, since the powdery carbonaceous material is preferentially consumed in the reduction reaction of the ore, it is clear that the quality constraint of the coke and the ore can be relaxed.

[0026]

EXAMPLE The method of the present invention was carried out using a test blast furnace, and its effectiveness was confirmed.

The test blast furnace has a furnace inner diameter of 800 mm and a height of 5.
It has 5 tulips and 3 tuyeres (120 ° intervals). A nozzle penetrating from the furnace wall to the inside of the furnace is installed at a position 300 mm above each tuyer, and powdered carbonaceous material is produced by N ₂ gas. Blew in.

As the powdery carbonaceous material, coal (C: 75%, H: 4%, O (oxygen): 8% and N: 1.4%) crushed to an average particle size of 0.5 mm or less was used. .

Coke has an average particle size of 20 mm and C: 88.
%, H: 0.5%, and N: 0.5%, and I type drum strengths of 88%, 85%, and 82% were used.

The ore is a sintered ore, having an average particle size of 8 mm, T. F
e: 57%, the reducibility specified by JIS is 70%, 65
% And 60% were used.

In carrying out the method of the present invention, the powdery carbonaceous material ratio was 200 kg / t, 50% of which was blown from the nozzle above the tuyere, and the remaining 50% was blown from the tuyere.
For comparison, a method of blowing all (100%) powdered carbonaceous material (200 kg / t) from the tuyere was carried out. In addition, a test using no carbonaceous material was also performed as a base.

The test results are shown in Table 2. As shown in these results, under the same raw material conditions (that is, the coke strength and the ore reducing property are the same), the inventive example has a smaller coke ratio than the comparative example, and the coke reduction amount is significantly improved. (Comparison of cases 1 and 7, 2 and 8, ..., or 5 and 11). In addition, it is clear from the comparison with the base that the coke consumption can be significantly reduced even in the comparative example.

When the coke reduction amount (that is, the coke ratio) is the same, the quality of coke and ore can be greatly relaxed (comparison between cases 6 and 12).

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

According to the method of the present invention, it is possible to reduce the consumption of coke, and it is also possible to use low-quality coke or ore, and compared with the conventional method of blowing carbonaceous material from the tuyere. Its economic value is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method of the present invention, and is a schematic diagram in the vicinity of a powder carbonaceous material supply nozzle mounting portion.

[Explanation of symbols]

1: Powdery carbonaceous material supply nozzle, 2: Tuyere, 3: Charged powdery carbonaceous material, 4: Powdery carbonaceous material that rises in a high temperature gas stream, 5: High temperature gas emitted from raceway, 6 : Attraction layer,
7: coke packed bed, 8: raceway, 9: furnace body

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Suyama 4-533 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Inventor Yu Ujizawa 4 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture 5-53, Sumitomo Metal Industries, Ltd. (72) Inventor Chika Uejo 4-53-3, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd.

Claims (2)

[Claims] 1. A pulverized carbonaceous material is mixed in a high temperature gas generated by the combustion of coke by hot air in front of the tuyere of a blast furnace, conveyed into the blast furnace by a high temperature gas stream, and used as a reducing agent in the blast furnace. A method of using carbonaceous material in a blast furnace, which is characterized in that 2. The method according to claim 1, wherein the powdered carbonaceous material is mixed into the high temperature gas through a nozzle penetrating into the furnace from the outer surface of the furnace wall installed above the tuyere of the blast furnace. How to use carbonaceous material in blast furnace.