JP3735184B2

JP3735184B2 - Blast furnace operation method

Info

Publication number: JP3735184B2
Application number: JP18462897A
Authority: JP
Inventors: 尚熊岡; 守政一田
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1997-06-26
Filing date: 1997-06-26
Publication date: 2006-01-18
Anticipated expiration: 2017-06-26
Also published as: JPH1112617A

Description

【０００１】
【発明の属する技術分野】
本発明は、休風時に発破という手段を用いて高炉炉芯部の通気性および通液性を維持もしくは改善する、高炉の操業方法に関するものである。
【０００２】
【従来の技術】
製銑用高炉は大量の銑鉄を生産できしかも熱効率が約９０％と極めて高い。このため現在でも銑鉄製造の主流を維持している。しかし、高炉は巨大な対向流移動層であるため、生産性、生産弾力性等に問題があり、安定した生産量と溶銑品質の確保のためにはより一層の制御性の向上が望まれている。
【０００３】
一方、高炉では製造コスト低減の観点から、安価原燃料使用操業や多量微粉炭吹き込み操業が実施されつつある。このような操業下では、鉱石・コ−クスの粉化が増加し、羽口から吹き込まれた微粉炭の未燃チャ−も合わせ、炉下部での粉率が上昇し、高炉内中心下部に形成され大部分がコ−クスから成る層である炉芯部の通気性・通液性の確保が困難となり炉芯不活性化を招き易い。炉芯不活性が進むと、送風圧力の変動・出銑滓排出困難などのいわゆる炉況悪化状態となり減風や大幅なる燃料原単位の上昇（クリ−ニング）をある期間余儀なくされ、計画生産量を維持できなくなる。
【０００４】
このようなことから、有効な炉芯の活性化技術の確立が望まれてきた。
炉芯不活性の改善手段としては、燃料比上昇や水蒸気添加など操業中操作の他に休風時に実施するいくつかの手段が開示されている。
特開平０６−９３３１９号公報、特開平０６−９３３２０号公報では、休風毎に複数の羽口を介して炉芯部の特性を測定して炉芯部の状態を判定し、要加熱部位の近傍の羽口から中空パイプを挿入して炉芯内コ−クスをサンプリングすることにより炉芯内に通気孔を設ける方法が開示されている。一方、特願平０７−２０９３０６号公報には、休風時に羽口より中空パイプを打ち込み、このパイプより休風立ち上げ時に炉芯内に送風することで炉芯の活性化をはかる方法が開示されている。
【０００５】
【発明が解決しようとする課題】
上記特開平０６−９３３１９号公報、特開平０６−９３３２０号公報、で開示されている方法、すなわち羽口コ−クスサンプリングにより炉芯内コ−クスを取り出して炉芯内に空洞の通気孔を設ける方法では、羽口コ−クスサンプリングにより形成された炉芯内への空洞の通気孔が送風立ち上げ時に確実に維持されている保証はなく、また特願平０７−２０９３０６号公報で開示されている方法、すなわち打ち込みパイプにより確実に炉内に送風する方法でも、送風後のパイプ溶融・消滅に従い、空洞が消滅するので、パイプ溶融までの炉芯内部への送風効果のみを期待していると言わざるを得ない。
【０００６】
従って、上記の各方法では、炉芯内へ高温ガスの一部を吹き込むことによる炉芯内コ−クス・メタル・スラグの加熱効果や粉除去効果に不十分な場合があり、これらの方法を実施しても操業改善に至らないことも生じ得るという問題を有している。
【０００７】
【課題を解決するための手段】
本発明はこのような従来の問題点に鑑み、炉芯内部への送風を阻害している羽口奥１〜３ｍの部位に存在する粉とコ−クス中あるいは微粉炭中のアッシュをバインダ−としたコ−クスのシェルである鳥の巣、および炉芯表層部の粉やスラグ・メタルの蓄積から生じる通気・通液阻害層を発破により根本的に破壊し、炉芯内部に高温の熱風を吹き込むことの障害を取り除くことにより、炉芯の通気・通液性（活性状態）を維持し、長期的に大幅なる生産量の低下を招くことなく高炉操業を継続する方法を提示するものである。
【０００８】
即ち、本発明は高炉休風時に１カ所以上の羽口を通して炉内に装入された先端部の閉じたパイプ先端内部に爆薬を装着、爆発させることにより高炉羽口奥部の炉内内容物の充填密度の高い部位を破壊し、高炉炉芯部の通気性および通液性の維持または改善をはかることを特徴とする高炉操業法である。
【０００９】
【発明の実施の形態】
本発明では、高炉休風時に、羽口から炉芯内に先端の閉じた中空パイプを、例えば、特願平０７−１２００２１号公報に開示されているような可搬型の打ち込み装置により打ち込む。さらに打ち込んだパイプをガイドとして羽口先端より炉芯内部に爆薬を挿入、炉外にまで引かれた導爆線を通じて爆発させる。炉芯発破作業により、高炉レ−スウェイ奥に粉とアッシュをバインダ−としたコ−クスのシェルである鳥の巣と、炉芯表層部の通気・通液性の悪い部位が破壊される。
【００１０】
そのため休風以前においてガス流通量が少ない状態であった炉芯内部に、羽口から吹き込まれる８００〜１３００℃の熱風が十分に供給されることとなる。炉芯内に吹き込まれた熱風は炉芯内コ−クスと反応して２０００℃近傍のＣＯリッチな還元ガスになり、炉芯内コ−クスを加熱すると同時に炉芯内にホ−ルドアップしているスラグ・メタルを溶解する。炉芯内コ−クスの加熱により炉芯内での粉コ−クスのソリュ−ションロス反応も進行するため、炉芯内の加熱・粉除去を確実に進めることができる。以上より炉芯部の通気・通液性が改善される。
【００１１】
積極的な炉芯活性度改善のためには一度の休風において４カ所以上の発破を実施する方法をとるべきである。一方、高微粉炭比操業（高Ｏ／Ｃ操業）のように炉下部への鉱石の負荷が高い操業の場合、定期的に１〜２カ所の発破を実施し、炉芯の活性度を常にある一定のレベルに維持しておくという方法もある。
【００１２】
適切なるパイプ打ち込み深度すなわち発破を実施する深度は高炉のサイズ・炉芯の充填状態により異なる。ただし、炉芯部の通気・通液性を阻害しているのは多くの場合上述したレ−スウェイ奥の鳥の巣から炉芯表層部、つまり羽口先端より炉内側に１〜３ｍ入った部位であり、この部位を破壊することがもっとも効果的である。
【００１３】
炉内高温部での変形防止のためパイプは打ち込み開始より爆薬装着終了まで水冷しておくことが好ましい。しかしながら、パイプ先端は水冷を実施しても、炉内の１５００℃以上赤熱コ−クスに加熱され高温になる可能性がある。従って爆薬の種類としては熱に対する感度の低いものが好ましい。尚、前記パイプには爆発力を炉内に確実に伝えるため、パイプ先端よりパイプの側面に適当な長さ・適当な数のスリットを設けることが望ましい。
【００１４】
【実施例】
以下、図面に示す実施例に基づいて具体的に説明する。
（実施例１）
内容積が４０００ｍ³ 以上で羽口数が３８本の大型高炉の休風時において、円周方向に約９０°間隔に４カ所の羽口を通して炉芯発破作業を行った。図１に示すように発破を行う前段階の作業として、先端キャップ１付きで側面にスリット１３を設けた中空パイプ２を打ち込む（図２（ａ）にその外部を示す）。この時パイプ先端部は炉芯コ−クス９内の鳥の巣１０の奥、羽口８先端より炉内側に２ｍ入った位置とした。このパイプをガイドとして爆薬３を先端部に装着し、引き続き、炉外側への爆風を防止する目的で砂袋１２を装着する（図２（ｂ）にその外部を示す）。その直後に爆薬に接続された導爆線４・電気雷管５・導線６を通じて高炉操業床１１に設置した電源スイッチ７を入れ爆発させた。
【００１５】
この結果、図３に示すように休風以前に低下していた炉芯の活性度を示す、炉底中心温度が上昇。さらにこれに伴い、送風圧の変動（σＰv ）・スリップの回数が激減し、炉芯発破実施以降、操業の安定度が高まった。
【００１６】
（実施例２）
内容積が４０００ｍ³ 以上で羽口数が３８本の大型高炉において毎月一度の休風時に２カ所の羽口からの炉芯発破を実施した。この高炉では図４の期間Ａにおいて炉芯不活性に起因すると思われる操業不安定状態となったため、期間Ｂにおいて大幅な燃料比の上昇（クリ−ニング操業）を実施し炉芯の活性状態および操業の安定度を回復させた。この後、期間Ｃにおいて実施例１と同様の作業にて、毎月の休風毎２カ所の羽口にて炉芯発破を実施したところ、炉芯の活性状態が長期的に維持され、風圧変動が小さく、スリップが少ないことに代表されるような安定操業が長期的に達成された。
【００１７】
【発明の効果】
以上示したように、本発明は高炉休風時に１カ所以上の羽口を通して炉内に装入された先端部の閉じたパイプ先端内部に爆薬を装着、爆発させることにより高炉羽口奥部の炉内内容物の充填密度の高い部位を破壊し、高炉炉芯部の通気性および通液性の維持または改善をはかる手段を提供するものである。これにより大幅なる燃料原単位の増加を伴なわずに炉芯の活性化を得ることが可能となった。また定期的な実施により活性状態を維持できたことより、長期安定操業達成への効果が確認できた。
【図面の簡単な説明】
【図１】炉芯発破法概要説明図
【図２】中空パイプ２の詳細を示した図
【図３】本発明実施前後の操業指標の推移図（１）
【図４】本発明実施前後の操業指標の推移図（２）
【符号の説明】
１先端キャップ
２中空パイプ
３爆薬
４導爆線
５電気雷管
６導線
７電源スイッチ
８羽口
９炉芯コ−クス
１０鳥の巣
１１操業床
１２砂袋
１３スリット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of operating a blast furnace that maintains or improves the air permeability and liquid permeability of a blast furnace core using a means of blasting when the wind is off.
[0002]
[Prior art]
The ironmaking blast furnace can produce a large amount of pig iron and has an extremely high thermal efficiency of about 90%. For this reason, the mainstream of pig iron production is still maintained. However, since the blast furnace is a huge counter-flow moving bed, there are problems in productivity, production elasticity, etc., and further improvement in controllability is desired in order to ensure stable production volume and hot metal quality. Yes.
[0003]
On the other hand, in the blast furnace, operations using low-cost raw fuel and large-scale pulverized coal injection operations are being implemented from the viewpoint of reducing manufacturing costs. Under such operations, ore and coke pulverization increased, and unburned char of pulverized coal blown from the tuyere increased. It is difficult to ensure the air permeability and liquid permeability of the furnace core portion, which is a layer formed mostly of coke, and tends to inactivate the furnace core. As the core deactivation progresses, so-called furnace conditions become worse, such as fluctuations in the blowing pressure and difficulty in discharging discharge, and wind reduction and a significant increase in fuel consumption (cleaning) are forced for a certain period of time. Cannot be maintained.
[0004]
Therefore, establishment of an effective core activation technology has been desired.
As means for improving the inactivity of the core, several means are disclosed that are implemented during off-air in addition to operations during operation such as increase in fuel ratio and addition of steam.
In Japanese Patent Application Laid-Open Nos. 06-93319 and 06-93320, the characteristics of the furnace core part are measured through a plurality of tuyere for each pause, and the state of the furnace core part is determined. A method is disclosed in which a hollow pipe is inserted from a nearby tuyere and a coke inside the furnace core is sampled to provide a vent hole in the furnace core. On the other hand, Japanese Patent Application No. 07-209306 discloses a method of activating a furnace core by driving a hollow pipe from a tuyere when the wind is off, and blowing air from the pipe into the furnace core when the wind is off. Has been.
[0005]
[Problems to be solved by the invention]
The method disclosed in Japanese Patent Laid-Open No. 06-93319 and Japanese Patent Laid-Open No. 06-93320, that is, the coke in the furnace core is taken out by tuyere coke sampling and a hollow vent hole is formed in the furnace core. In the method of providing, there is no guarantee that the hollow vent hole in the furnace core formed by tuyere coke sampling is reliably maintained at the time of air blow-up, and is disclosed in Japanese Patent Application No. 07-209306. Even if it is a method that is surely blown into the furnace with the driven pipe, the cavity disappears as the pipe melts and disappears after blowing, so only the blowing effect inside the furnace core until the pipe melts is expected I must say.
[0006]
Therefore, in each of the above methods, there are cases where the heating effect and powder removal effect of coke, metal, and slag in the core by blowing a part of the high temperature gas into the core are insufficient. There is a problem that even if implemented, it may not lead to operational improvements.
[0007]
[Means for Solving the Problems]
In view of the above-described conventional problems, the present invention binds powder and ash in coke or pulverized coal existing in a portion 1 to 3 m deep behind the tuyere that impedes ventilation into the core. The blast of the bird's nest, which is the shell of the coke, and the aeration / flow-inhibition layer resulting from the accumulation of powder and slag / metal on the surface of the core of the core, is blasted, and hot air This is a method to maintain the ventilation and liquid permeability (active state) of the furnace core by removing the obstacles to blowing the blast furnace, and to continue the blast furnace operation without causing a significant decrease in production over the long term. is there.
[0008]
That is, in the present invention, when the blast furnace is shut down, the explosive is placed inside the closed pipe tip inserted into the furnace through one or more tuyere, and the contents inside the furnace at the back of the blast furnace tuyere are exploded. This is a blast furnace operating method characterized by destroying a portion having a high packing density and maintaining or improving the air permeability and liquid permeability of the blast furnace core.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, when the blast furnace is shut down, a hollow pipe having a closed tip from the tuyere into the furnace core is driven by, for example, a portable driving device as disclosed in Japanese Patent Application No. 07-120021. Furthermore, explosives are inserted into the core of the furnace core from the tip of the tuyere using the driven pipe as a guide, and explode through an explosive wire drawn to the outside of the furnace. The core blasting operation destroys the bird's nest, which is a coke shell with powder and ash as a binder, at the back of the blast furnace raceway and the poorly ventilated and liquid-permeable portion of the core surface layer.
[0010]
Therefore, the hot air of 800 to 1300 ° C. blown from the tuyere is sufficiently supplied into the furnace core where the gas flow rate was small before the resting wind. The hot air blown into the furnace core reacts with the coke inside the furnace core to become a CO-rich reducing gas near 2000 ° C., and the coke inside the furnace core is heated and held up at the same time. Melt the slag metal. The solution loss reaction of the powder coke in the furnace core also proceeds due to the heating of the furnace core coke, so that the heating and powder removal in the furnace core can be surely advanced. From the above, the ventilation and liquid permeability of the furnace core is improved.
[0011]
In order to positively improve the core activity, a method of blasting 4 or more locations in a single wind break should be used. On the other hand, in the case of operations where the load of ore on the lower part of the furnace is high, such as high pulverized coal ratio operation (high O / C operation), the blasting of 1 to 2 places is carried out regularly, and the activity of the core is always kept There is also a way to keep it at a certain level.
[0012]
The appropriate pipe driving depth, that is, the depth at which blasting is carried out, depends on the size of the blast furnace and the filling state of the core. However, in most cases, the core / air permeability of the furnace core is blocked from the bird's nest at the back of the raceway to the furnace core surface, that is, 1 to 3 m inside the furnace from the tuyere tip. It is a site, and it is most effective to destroy this site.
[0013]
In order to prevent deformation in the high temperature part in the furnace, the pipe is preferably water cooled from the start of driving until the end of explosive mounting. However, even if the pipe tip is water-cooled, it may be heated to red hot coke at 1500 ° C. or higher in the furnace and become high temperature. Therefore, the kind of explosive is preferably one having low sensitivity to heat. In order to reliably transmit the explosive force into the furnace, it is desirable to provide an appropriate length and an appropriate number of slits on the side of the pipe from the end of the pipe.
[0014]
【Example】
Hereinafter, a specific description will be given based on an embodiment shown in the drawings.
Example 1
When a large blast furnace with an internal volume of 4000 m ³ or more and 38 tuyere was closed, the core was blasted through four tuyere at intervals of about 90 ° in the circumferential direction. As shown in FIG. 1, as a pre-stage operation for blasting, a hollow pipe 2 with a tip cap 1 and provided with a slit 13 on the side surface is driven (FIG. 2 (a) shows the outside). At this time, the tip of the pipe was set at a depth of 2 m inside the furnace from the back of the bird's nest 10 in the furnace core coke 9 and the tip of the tuyere 8. Using this pipe as a guide, the explosive 3 is attached to the tip, and then a sand bag 12 is attached for the purpose of preventing a blast to the outside of the furnace (the outside is shown in FIG. 2 (b)). Immediately after that, the power switch 7 installed on the blast furnace operating floor 11 was put through the detonation wire 4, the electric detonator 5, and the lead wire 6 connected to the explosive to explode.
[0015]
As a result, as shown in FIG. 3, the core temperature at the bottom of the furnace, which indicates the activity of the core that had been reduced before the break, increased. Along with this, the fluctuation of the blast pressure (σPv) and the number of slips decreased drastically, and the stability of the operation increased after the blasting of the core.
[0016]
(Example 2)
In a large blast furnace with an internal volume of 4000 m ³ or more and 38 tuyere, blasting of the core from two tuyere was carried out at the time of a monthly break. In this blast furnace, the operation unstable state that seems to be caused by the core deactivation in the period A of FIG. 4 was brought about. Therefore, in the period B, the fuel ratio was significantly increased (cleaning operation), and the core active state and Restored operational stability. After this, during the period C, the core blasting was carried out at the tuyere at two locations every month, with the same operation as in Example 1; Stable operation as represented by small and low slip was achieved in the long term.
[0017]
【The invention's effect】
As described above, the present invention can be applied to the inner part of the blast furnace tuyere at the back of the blast furnace tuyeres by attaching and exploding explosives inside the closed pipe tip at the tip inserted into the furnace through one or more tuyere during blast furnace quiescence The present invention provides a means for destroying a portion having a high packing density in the furnace contents and maintaining or improving the air permeability and liquid permeability of the blast furnace core. As a result, it has become possible to activate the core without greatly increasing the fuel consumption rate. Moreover, since the active state could be maintained by regular implementation, the effect of achieving long-term stable operation could be confirmed.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of the outline of the core blasting method. FIG. 2 is a diagram showing details of the hollow pipe 2. FIG. 3 is a transition diagram of operation indexes before and after the present invention is implemented (1).
[Fig. 4] Transition diagram of operation index before and after the implementation of the present invention (2)
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tip cap 2 Hollow pipe 3 Explosive 4 Explosive line 5 Electric detonator 6 Conductor 7 Power switch 8 Tail 9 Core core 10 Bird's nest 11 Operation floor 12 Sand bag 13 Slit

Claims

A high packing density of the contents inside the blast furnace tuyere at the back of the blast furnace tuyere by installing and exploding explosives inside the closed pipe tip of the pipe inserted into the furnace through one or more tuyere during blast furnace quiescence A method for operating a blast furnace, characterized by destroying the site and maintaining or improving the air permeability and liquid permeability of the core of the blast furnace.