JP3702008B2

JP3702008B2 - Blast furnace operation method

Info

Publication number: JP3702008B2
Application number: JP18666495A
Authority: JP
Inventors: 正義高尾; 哲也塩田; 基樹本田
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1995-06-30
Filing date: 1995-06-30
Publication date: 2005-10-05
Anticipated expiration: 2020-10-05
Also published as: JPH0920904A

Description

【０００１】
【産業上の利用分野】
この発明は高炉炉内の装入物分布を制御することで常に安定したガス流を確保して炉況の安定維持を図るための操業方法に関するものである。
【０００２】
【従来の技術】
現在、高炉においては、炉頂より粒径５０ｍｍ以下の焼結鉱、鉄鉱石、ペレット等の鉄原料および燃料としてコ−クスが装入され、それら鉄原料および燃料は炉下部から上昇する高温のガスとの接触により複雑な化学変化を起こし、溶銑の生成へと至っている。しかし、前記鉄原料の粒度、装入分布状態などは常に一定ではなく、この変動に伴って炉内のガス流分布は大きく変わり、そしてこのガス流分布の変動は炉況の安定に大きく影響している。
【０００３】
このため、例えば特開昭５５−６２１０６号公報に提案のように炉壁側に細粒、中心部には粗粒の鉄原料およびコ−クスを装入してガス流分布を調整し、これによりガス利用効率を向上して燃料比の低減を図る方法がある。
【０００４】
【発明が解決しようとする課題】
しかし、近年は５０００ｍ³ 級の超大型高炉が主流となり、その炉口径は１０ｍ程度と非常に大きい。この炉口径が大きいということは、中心部と炉壁部の距離が遠くなる。こうなれば中心部から炉壁部となる全域においての装入物の分布調整は不十分であり、特に、通常の鉄原料粒度（５０ｍｍ〜２５ｍｍ：２０％、２５ｍｍ未満〜１５ｍｍ：４０％、１５ｍｍ未満〜５ｍｍ：３６％、５ｍｍ以下：４％）では、鉄原料の各鉱石の形状（表面の凹凸）が一定でないため炉壁から中心部に流れ込む状態、つまり装入物分布が大きく変動し、装入物分布の再現性が殆ど無いことよりガス流分布の制御性は低いものである。
【０００５】
このため、適切なガス流分布の確立は困難となり、高炉炉内反応効率の低下を惹起する等の問題を有し、高炉炉況に悪影響を与える原因になる。
本発明は、前記問題を有することなく超大型高炉においても炉壁から中心まで確実に装入物分布を調整でき、安定したガス流分布を確保することを課題とするものである。
【０００６】
【課題を解決しようとする手段】
本発明は上記課題を解決するためになされたものでありその手段１は、高炉炉内にコ−クスと粒径５０ｍｍ以下の鉄原料を交互に装入して高炉を操業する方法において、前記鉄原料を複数バッチに分割し、その複数バッチを順次装入するに際し、高炉炉頂部の炉径方向における複数位置のガス流量比を求め、炉中心部のガス流量比が該位置の基準ガス流量比より高く側壁部または中間部のガス流量比が該位置の基準ガス流量比より低いときには、前記複数バッチのうちの最初に装入するバッチ以外のいずれか１つのバッチの鉄原料細粒部分の配合割合を増調整し、炉中心部のガス流量比が該位置の基準ガス流量比より低く側壁部または中間部のガス流量比が該位置の基準ガス流量比より高いときには、前記複数バッチのうちの最初に装入するバッチ以外のいずれか１つのバッチの鉄原料細粒部分の配合割合を減調整する方法である。
【０００７】
さらに、手段２は、前記手段１の配合割合を調整する鉄原料中の細粒部分の粒径を７ｍｍ以下としたものである。
また、前記炉径方向複数位置のガス流量を測定する方法としては、ゾンデに流量計を設けて直接測定しても良く、また、ゾンデに流速計を設けて炉内ガス流速を求め、これから流量を算定しても良い。さらにその他の方法で求めてもよい。
【０００８】
【作用】
図１に実炉を１／３のサイズにしたモデル高炉で、鉄原料装入バッチの一つに７ｍｍ以下の細粒分の配合割合を調整した際のガス流分布の影響を試験した結果を示す。この際の鉄原料の装入モ−ドは鉄原料Ａを装入した後、鉄原料Ｂを装入したものである。
【０００９】
ここでは、表１に示すように、鉄原料Ｂには７ｍｍ未満の細粒鉄原料を鉄原料Ａより多量に配合し、その配合割合は１バッチに於ける鉄原料量に対して鉄原料Ａは３．９％、鉄原料Ｂは１２．９％である。
【００１０】
【表１】

【００１１】
図１より細粒鉄原料を３．９％配合した鉄原料Ａは１２．９％配合した鉄原料Ｂに比べ、非常に中心部分の層厚が厚いことが確認される。しかし、中心部分の層厚の差が大きいのにも係わらず、壁際の層厚の差は中心部の差程大きくないことが判明した。
これは、今度装入した鉄原料が前に装入された鉄原料上を転がって炉中心方向に流れ込む際に、この装入した鉄原料が堆積する過程で主に粗粒鉄原料によって凹凸を有する状態になる。そして、この凹凸内に細粒鉄原料が流入して平面が平滑状態となって滑り易くなることから、前記鉄原料Ａに比して鉄原料Ｂの方が中心部分へ流れ込む割合が高くなるものと推定できる。
【００１２】
また、鉄原料の１チャ−ジは複数バッチに分割して装入されており、最初に装入するバッチは比較的柔らかいコ−クス層上に落下して、その上を炉中心方向に流れ込むことから装入した鉄原料の流れ込み状態が悪く、しかも、その調整が難しい。反面、前記最初のバッチ以外のバッチは固い鉄原料上に落下して、その上を炉中心方向に流れ込むことから装入した鉄原料の流れ込み状態が良く、さらに、その調整が容易になる。
そして、この鉄原料の層厚が厚ければ炉内を上昇するガス流は抑えられる方向であり、試験では細粒鉄原料の配合割合を調整することにより上記ガス流分布の制御が可能となることがわかる。
【００１３】
さらに、配合割合を調整する鉄原料中の細粒部分の粒径を７ｍｍ以下とするのは、これ以上の粒径であると前記流れ込み状態の大幅な向上がなく、しかも、その変化量が小さくなる。これは、粒径が７ｍｍ以下になると安息角が急激に小さくなり、細粒の流れ込み状態が悪化する結果、炉中心側になるに従って、粗粒鉄原料で形成された凹凸部を埋める細粒が少なくなることに起因するものと推測される。
【００１４】
【実施例】
以下、本発明の１実施例を内容積が５０００ｍ³ の鉄原料とコ−クスの装入チャ−ジが各々２バッチ（Ｃ１↓、Ｃ２↓、Ｏ１↓、Ｏ２）であるベル式超大型高炉を用いて説明する。
表２の装入物は焼結鉱８０％、鉄鉱石２０％の割合の鉄原料であり、７ｍｍ以下の細粒鉄原料は全量焼結鉱とした。
また、細粒焼結鉱を増配合したバッチのみ炉内に設けたア−マ−プレイト（ＭＡ）のノッチは０（壁際装入）とした。これは、壁際のガス流制御と炉中心部へ鉄原料が過度に流れ込むことによる中心ガス流の減少を防ぐためである。
また、炉径方向における複数位置のガス流量の測定はシャフト、上部に設けた流量計を有するゾンデを用いて、炉壁際部、炉中心部、中間部のガス量を測定した。
【００１５】
【表２】

【００１６】
【表３】

【００１７】
表２に示すように、比較例１においてＯ２として表３の鉄原料Ｂを使用しているため、その細粒部が８％で、炉中心部のガス流量比が基準ガス流量比（４２％）より高く、さらに、壁側部のガス量比が基準ガス流量比（２８％）より低く、ガス利用率が低いので、実施例１のようにＯ２に鉄原料Ａを使用して細粒部の配合割合を１１％（３％増加）にして操業した結果、炉径方向の各位置のガス流量比が各基準ガス流量比に近づき、ガス利用率の向上を図れた。
【００１８】
比較例２において装入鉄原のＯ２として鉄原料Ｂを使用しているため、その細粒部が８％で、炉中心部のガス流量比が基準ガス流量比より低く、中間部は基準ガス流量比（３０％）より高く、ガス利用率が低いので、実施例２のようにＯ２に鉄原料Ｃを使用して細粒部を５％（３％減）にして操業した結果、炉径方向の各位置のガス流量比が基準ガス流量比に近づき、ガス利用率の向上を図れた。
【００１９】
比較例３はＯ１、Ｏ２として表３の鉄原料Ｃを使用しているため、炉中心部のガス流量比が基準ガス流量比より高く、壁側部のガス量比が基準ガス流量比より低く、ガス利用率が低いので、比較例４のようにＯ１、Ｏ２の両方に鉄原料Ｂを使用して細粒部の配合割合を３％増加（５％→８％）して操業した結果、炉径方向の各位置のガス流量比には殆ど変化がなく、ガス利用率の向上は殆どなかった。
【００２０】
このように、実施例１、２は比較例１、２に対し、炉内ガス流分布が適正になり、これにより、ガス利用率も上昇し、燃料比の低減を図ることができた。
【００２１】
さらに、比較例３、４よりＯ１、Ｏ２の両バッチにおける鉄原料中の細粒部の配合割合を同時に調整してもガス流量比の調整量は極めて小さいことが分かる。このため、Ｏ１、Ｏ２のいずれか片方バッチの細粒部の調整をしないとその効果を十分に享受できないことが分かる。
【００２２】
【発明の効果】
以上説明したように、本発明は鉄原料装入チャ−ジの一つのバッチの鉄原料中における細粒部の配合割合を調整することにより、所望の炉内ガス流分布を得ることが可能となり、燃料比の低減が図れると共に安定した高炉操業を継続維持できる等の多大な効果を奏するものである。
【図面の簡単な説明】
【図１】細粒鉄原料の配合割合と炉径方向の層厚分布の関係を示した図[0001]
[Industrial application fields]
The present invention relates to an operation method for always maintaining a stable gas flow by controlling the distribution of charges in a blast furnace furnace so as to maintain stable furnace conditions.
[0002]
[Prior art]
Currently, in blast furnaces, coke is charged as an iron raw material and fuel such as sintered ore, iron ore, pellets and the like having a particle size of 50 mm or less from the top of the furnace, and the iron raw material and fuel are heated at a high temperature rising from the lower part of the furnace. Contact with gas causes complex chemical changes that lead to the production of hot metal. However, the particle size and charging distribution of the iron raw material are not always constant, and the gas flow distribution in the furnace changes greatly with this fluctuation, and the fluctuation of the gas flow distribution greatly affects the stability of the furnace condition. ing.
[0003]
For this reason, for example, as proposed in Japanese Patent Laid-Open No. 55-62106, a fine-grained iron raw material and coke are introduced into the furnace wall side to adjust the gas flow distribution. Therefore, there is a method for improving the gas utilization efficiency and reducing the fuel ratio.
[0004]
[Problems to be solved by the invention]
However, in recent years, ultra-large blast furnaces of 5000 m ³ class have become mainstream, and the diameter of the furnace is as large as about 10 m. This large furnace diameter means that the distance between the center and the furnace wall is increased. In this case, the distribution of the charge in the entire region from the central part to the furnace wall part is insufficient, and in particular, the normal iron raw material particle size (50 mm to 25 mm: 20%, less than 25 mm to 15 mm: 40%, 15 mm Less than 5 mm: 36%, 5 mm or less: 4%), the shape (surface irregularities) of each ore of the iron raw material is not constant, so that the state of flowing from the furnace wall to the center, that is, the distribution of the charge greatly fluctuates. Since there is almost no reproducibility of the charge distribution, the controllability of the gas flow distribution is low.
[0005]
For this reason, it is difficult to establish an appropriate gas flow distribution, which causes problems such as a decrease in reaction efficiency in the blast furnace, and causes a bad influence on the blast furnace condition.
It is an object of the present invention to ensure stable gas flow distribution by adjusting the charge distribution from the furnace wall to the center even in a very large blast furnace without having the above problems.
[0006]
[Means to solve the problem]
The present invention has been made to solve the above-mentioned problems, and means 1 is a method for operating a blast furnace by alternately charging coke and an iron raw material having a particle size of 50 mm or less into a blast furnace. When dividing the iron raw material into multiple batches and sequentially charging the multiple batches, obtain the gas flow ratio at multiple positions in the furnace radial direction at the top of the blast furnace furnace, and the gas flow ratio at the furnace center is the reference gas flow rate at that position When the gas flow rate ratio of the side wall portion or the intermediate portion is higher than the ratio and lower than the reference gas flow rate ratio of the position, the iron raw material fine particle portion of any one batch other than the first batch charged among the plurality of batches When the mixing ratio is increased and the gas flow ratio at the furnace center is lower than the reference gas flow ratio at the position and the gas flow ratio at the side wall or the middle is higher than the reference gas flow ratio at the position, First charge Tsu is a method of adjusting reducing the blending ratio of the iron raw material granules portions of any one batch of non-switch.
[0007]
Furthermore, the means 2 makes the particle size of the fine grain part in the iron raw material which adjusts the mixture ratio of the means 1 be 7 mm or less.
In addition, as a method of measuring the gas flow rate at a plurality of positions in the furnace radial direction, a flowmeter may be provided directly on the sonde, or a flowmeter may be provided on the sonde to obtain the gas flow velocity in the furnace, and the flow rate from this May be calculated. Further, it may be obtained by other methods.
[0008]
[Action]
Figure 1 shows the results of testing the effect of gas flow distribution when adjusting the blending ratio of fine particles of 7 mm or less in one of the iron raw material charging batches in a model blast furnace with an actual furnace of 1/3 size. Show. The charging mode of the iron raw material at this time is the one in which the iron raw material B is charged after the iron raw material A is charged.
[0009]
Here, as shown in Table 1, iron raw material B is blended with iron raw material B in a larger amount than iron raw material A, and the blending ratio is iron raw material A with respect to the amount of iron raw material in one batch. Is 3.9% and iron raw material B is 12.9%.
[0010]
[Table 1]

[0011]
From FIG. 1, it is confirmed that the iron raw material A containing 3.9% of the fine-grained iron raw material has a much thicker central portion than the iron raw material B containing 12.9%. However, it was found that the difference in the layer thickness near the wall was not as great as the difference in the central portion, despite the large difference in the layer thickness at the central portion.
This is because when the charged iron raw material is rolled on the previously charged iron raw material and flows toward the furnace center, the roughened iron raw material mainly causes unevenness in the process of depositing the charged iron raw material. It will have a state. And since the fine-grained iron raw material flows into the irregularities and the flat surface becomes smooth and becomes slippery, the proportion of the iron raw material B flowing into the central portion is higher than that of the iron raw material A. Can be estimated.
[0012]
In addition, one charge of the iron raw material is divided and charged into a plurality of batches, and the first charged batch falls on a relatively soft coke layer and flows into the center of the furnace. For this reason, the state of the charged iron raw material is poor and its adjustment is difficult. On the other hand, batches other than the first batch fall on the hard iron raw material, and flow onto it in the direction of the center of the furnace, so that the charged state of the iron raw material is good and the adjustment becomes easy.
And if the layer thickness of this iron raw material is thick, the gas flow rising in the furnace is in a direction to be suppressed. In the test, the gas flow distribution can be controlled by adjusting the mixing ratio of the fine-grained iron raw material. I understand that.
[0013]
Furthermore, the particle size of the fine-grained portion in the iron raw material for adjusting the blending ratio is set to 7 mm or less. When the particle size is larger than this, there is no significant improvement in the flowing state, and the change amount is small. Become. This is because when the particle size is 7 mm or less, the angle of repose sharply decreases and the flow of fine particles deteriorates. As a result, the fine particles filling the uneven portions formed of the coarse iron raw material become closer to the furnace center side. This is presumed to be due to the decrease.
[0014]
【Example】
In the following, one embodiment of the present invention is a bell-type super-large blast furnace with an internal volume of 5000 m ³ of iron raw material and coke charging charge in two batches (C1 ↓, C2 ↓, O1 ↓, O2). Will be described.
The charge in Table 2 was an iron raw material with a ratio of 80% sintered ore and 20% iron ore, and the fine iron raw material of 7 mm or less was all sintered ore.
Moreover, the notch of the armor plate (MA) provided in the furnace only for the batch in which the fine-grained sintered ore was added was set to 0 (charging by the wall). This is to prevent a decrease in the central gas flow due to excessive control of the gas flow at the wall and excessive iron flow into the furnace center.
Further, the gas flow rate at a plurality of positions in the furnace radial direction was measured by using a sonde having a shaft and a flow meter provided at the upper part, and measuring the gas amounts at the furnace wall edge, the furnace center, and the middle part.
[0015]
[Table 2]

[0016]
[Table 3]

[0017]
As shown in Table 2, since the iron raw material B of Table 3 is used as O2 in Comparative Example 1, the fine-grained portion is 8%, and the gas flow ratio in the furnace center is the reference gas flow ratio (42% ), And the wall side portion gas volume ratio is lower than the reference gas flow rate ratio (28%), and the gas utilization rate is low. As a result, the gas flow ratio at each position in the furnace radial direction approached each reference gas flow ratio, and the gas utilization rate was improved.
[0018]
In Comparative Example 2, since the iron raw material B is used as O2 of the charged iron raw material, the fine-grained portion is 8%, the gas flow ratio in the furnace center is lower than the reference gas flow ratio, and the intermediate portion is the reference gas. As the gas flow rate is higher than the flow rate ratio (30%) and the gas utilization rate is low. The gas flow ratio at each position in the direction approached the reference gas flow ratio, and the gas utilization rate was improved.
[0019]
Since the comparative example 3 uses the iron raw material C of Table 3 as O1 and O2, the gas flow rate ratio of a furnace center part is higher than a reference gas flow rate ratio, and the gas amount ratio of a wall side part is lower than a reference gas flow rate ratio. Since the gas utilization rate is low, as a result of operation using the iron raw material B for both O1 and O2 as in Comparative Example 4 and increasing the blending ratio of the fine-grained portion by 3% (5% → 8%), There was almost no change in the gas flow ratio at each position in the furnace radial direction, and the gas utilization rate was hardly improved.
[0020]
As described above, the gas flow distribution in the furnace in Examples 1 and 2 was more appropriate than those in Comparative Examples 1 and 2 , thereby increasing the gas utilization rate and reducing the fuel ratio.
[0021]
Furthermore, it can be seen from Comparative Examples 3 and 4 that the adjustment amount of the gas flow rate ratio is extremely small even if the blending ratio of the fine-grained portion in the iron raw material in both batches O1 and O2 is adjusted simultaneously. For this reason, it turns out that the effect cannot fully be enjoyed unless the fine grain part of either one batch of O1 and O2 is adjusted.
[0022]
【The invention's effect】
As described above, the present invention makes it possible to obtain a desired in-furnace gas flow distribution by adjusting the mixing ratio of the fine-grained portion in the iron raw material of one batch of the iron raw material charging charge. As a result, the fuel ratio can be reduced and a great effect can be achieved, such as the continuous maintenance of stable blast furnace operation.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the mixing ratio of fine iron raw material and the layer thickness distribution in the furnace radial direction.

Claims

In the method of operating a blast furnace by alternately charging coke and iron raw material having a particle size of 50 mm or less into a blast furnace furnace, the iron raw material is divided into a plurality of batches, and when the plurality of batches are sequentially charged, Obtain the gas flow ratio at multiple positions in the furnace radial direction at the top of the furnace, the gas flow ratio at the furnace center is higher than the reference gas flow ratio at the position, and the gas flow ratio at the side wall or in the middle is the reference gas flow ratio at the position When it is lower, the blending ratio of the iron raw material fine grain portion of any one batch other than the batch charged first among the plurality of batches is increased and the gas flow ratio in the furnace center is the reference gas at the position. When the gas flow ratio of the side wall or the intermediate portion is lower than the flow rate ratio and higher than the reference gas flow rate ratio at the position, the iron raw material fine particle portion of any one batch other than the batch charged first among the plurality of batches Decrease blending ratio of Blast furnace method operation, characterized by.

A method for operating a blast furnace according to claim 1, wherein the particle size of the fine-grained portion in the iron raw material for adjusting the blending ratio is 7 mm or less.