JP5353118B2 - Blast furnace operation method - Google Patents

Blast furnace operation method Download PDF

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JP5353118B2
JP5353118B2 JP2008215607A JP2008215607A JP5353118B2 JP 5353118 B2 JP5353118 B2 JP 5353118B2 JP 2008215607 A JP2008215607 A JP 2008215607A JP 2008215607 A JP2008215607 A JP 2008215607A JP 5353118 B2 JP5353118 B2 JP 5353118B2
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stave
cooling water
cooling
temperature
blast furnace
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JP2010048528A (en
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康寛 才木
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Nippon Steel Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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  • Blast Furnaces (AREA)
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an operating method of a melting furnace capable of performing an operation of low reduction material ratio without changing a charging method controlled to optimize reaction efficiency and without changing equipment significantly fluctuating costs and production. <P>SOLUTION: A thickness of attachment formed on a furnace wall section in the melting furnace is adjusted by controlling a temperature of cooling water supplied from a cooling water supply system to a stave within a prescribed range by using the stave composed of a shell disposed on a peripheral edge section of the melting furnace and a cooling mechanism disposed inside of the shell, and a stave cooling system having the cooling water supply system for supplying the cooling water to the stave and a cooling water discharging system for discharging the cooling water passing inside of the stave. An upper limit of a water temperature of the cooling water supplied from the cooling water supply system to the stave is preferably determined so that a temperature of the cooling water discharged from the stave to the stave cooling water discharging system reaches a prescribed temperature or lower. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

本発明は、高炉の炉体をステーブによって保護するに際して、ステーブに通水する冷却水温を管理して高炉を制御する方法に関する。 The present invention, when protecting the high furnace furnace body by stave, manages the cooling water temperature of Rohm stave relates to a method for controlling the blast furnace.

高炉などの溶解炉の内部炉壁構造として、鉄皮の内側に内部冷却機構を備えたステーブ（クーリングステーブ、ステーブクーラなどとも称される。）を設け、このステーブの内側（炉内側）に耐火物からなる炉体が保持される構造が採用されている。ステーブの本体（鉄皮）内部には冷却水を通水する管が設けられており、この冷却水によって炉体を冷却して炉内の熱負荷から保護している。また、ステーブは複数の鉄皮と冷却水配管とからなる部分構造体が段をなして連結されて炉体を覆うように構成されている。このため、ステーブの各部に配置される部分構造体を個別に示す場合には「最下部ステーブ」（最下部に配置される部分構造体）のように称する。   As an internal furnace wall structure of a melting furnace such as a blast furnace, a stave (also called a cooling stave or a stave cooler) provided with an internal cooling mechanism is provided inside the iron shell, and a fireproof is provided inside the stave (furnace inside). A structure in which a furnace body made of an object is held is employed. A pipe through which cooling water flows is provided inside the main body (iron skin) of the stave, and the furnace body is cooled by this cooling water to protect it from the heat load in the furnace. In addition, the stave is configured such that partial structures composed of a plurality of iron skins and cooling water pipes are connected in stages to cover the furnace body. For this reason, when the partial structure arrange | positioned at each part of a stave is shown separately, it will be called as "the lowermost stave" (partial structure arrange | positioned at the lowest part).

図７に一般的な高炉ステーブ冷却水配管の概要を示す。ステーブに通水する冷却水はポンプによりまず最下部ステーブの配管に給水され、この最下部ステーブを冷却する。続いて、最下部ステーブに連結される上段のステーブ、その後はさらに連結される上段のステーブを順次冷却した後に、炉上部に配置される最上部ステーブの配管より排水される。排水された水は、最上部ステーブの排水配管に連結される熱交換器によって冷却を施された後、一旦貯水タンクに戻る。そして、貯水タンクよりポンプを介して再び最下部ステーブに導入される。ポンプより最下部ステーブに導入される部位に給水温度計が、最上部ステーブより排水される部位に排水温度計が設置されている。また、図示していないが、各段のステーブにはステーブ温度を測定するために温度計が設置されている。   FIG. 7 shows an outline of general blast furnace stave cooling water piping. The cooling water flowing through the stave is first supplied to the pipe of the lowermost stave by the pump, and the lowermost stave is cooled. Subsequently, the upper stave connected to the lowermost stave, and then the upper stave connected further to the lower stave are sequentially cooled, and then drained from the pipe of the uppermost stave arranged in the upper part of the furnace. The drained water is cooled by a heat exchanger connected to the drain pipe of the uppermost stave and then returns to the water storage tank. Then, the water is again introduced into the lowermost stave through the pump from the water storage tank. A feed water thermometer is installed at a site where the pump is introduced into the lowermost stave, and a drainage thermometer is installed at a site where the water is drained from the uppermost stave. Although not shown, a thermometer is installed on each stage stave to measure the stave temperature.

高炉操業において、ステーブは炉体を熱負荷から保護するという機能において重要である事は言うまでもないが、炉体を冷却することに由来して、炉内の内容物に大きな影響を与えるものである。そのために、ステーブによる冷却に関して適切な操業技術が要請されており、実際に高炉操業に対する影響やステーブに関連した操業方法に関しては多くの知見が開示されている。   In blast furnace operation, the stave is important in the function of protecting the furnace body from heat load, but it has a great influence on the contents in the furnace because it cools the furnace body. . Therefore, an appropriate operation technique is required for cooling by the stave, and a lot of knowledge is disclosed regarding the influence on the blast furnace operation and the operation method related to the stave.

まず、ステーブ冷却により高炉炉内からの抜熱量が多くなると、銑鉄生成に必要なエネルギーが増大して、還元材比（銑鉄生成に必要な還元材の原単位、通常は銑鉄１トンあたり使用する還元材量（ｋｇ）で表される。）が上昇するので、ステーブからの抜熱量は極力抑制することが望ましい事が、例えば特許文献１に述べられている。   First, when the amount of heat removed from the blast furnace increases due to stave cooling, the energy required for producing pig iron increases, and the ratio of reducing material (the basic unit of reducing material necessary for producing pig iron, usually used per ton of pig iron. For example, Patent Document 1 describes that it is desirable to suppress the amount of heat removed from the stave as much as possible.

ところで、高炉炉内からの抜熱量の大小は、ステーブ冷却の強弱とは必ずしも対応しない。ステーブ冷却が過剰だと、炉内炉壁部に付着物（炉内のガス流に含まれる微粉の鉄鉱石やコークスに含まれる金属成分などが炉壁で凝集・付着したものであり、その溶融温度は溶銑やスラグと同様に９００〜１２００℃である。）が生成し、この付着物は熱伝導度が小さいので、却って抜熱量は低減されることになる。しかしながら、このような操業により高炉操業が必ずしも良好となるものではなく、特許文献２には、炉内炉壁部に生成した付着物が大きくなると、装入物の円滑な降下およびガスの通気性を阻害して、高炉操業を不安定にする事が述べられており、その対策として、付着物を機械的に除去するための装置が開示されている。   By the way, the amount of heat extracted from the blast furnace does not necessarily correspond to the strength of stave cooling. If stave cooling is excessive, deposits on the furnace wall in the furnace (fine iron ore contained in the gas flow in the furnace and metal components contained in coke agglomerate and adhere to the furnace wall and melt. The temperature is 900 to 1200 ° C. as in the case of hot metal and slag.) Since this deposit has a low thermal conductivity, the amount of heat removal is reduced. However, the operation of the blast furnace is not necessarily improved by such an operation, and in Patent Document 2, if the deposits generated on the furnace wall in the furnace become large, the material is smoothly lowered and the gas permeability is increased. It is described that the operation of the blast furnace is made unstable, and an apparatus for mechanically removing deposits is disclosed as a countermeasure.

また、特許文献３には、炉壁部を過剰に冷却すると鉄鉱原料の粉化現象が発生し、この現象がガスの通気性阻害要因となって高炉内ガス流れ変動となり炉況悪化に繋がることが述べられている。そこで、炉壁部の過剰冷却を防止する為、居包み煉瓦を用いた緩冷却タイプのステーブが提案されている。   Further, in Patent Document 3, if the furnace wall is excessively cooled, a pulverization phenomenon of the iron ore raw material occurs, and this phenomenon becomes a gas air permeability impeding factor, resulting in fluctuations in gas flow in the blast furnace, leading to deterioration of the furnace condition. Is stated. Therefore, in order to prevent overcooling of the furnace wall, a slow cooling type stave using a living brick has been proposed.

一方、ステーブは炉体を保護するだけでなく、ステーブ本体や冷却水配管に設置された温度計により測定されたステーブ温度や冷却水温度、給排水の冷却水温度から算出される抜熱量などの情報（以下、「温度計情報」と称する。）から高炉内状況を推定することができる。そこで、これらの温度計情報から操業方法の指針を得ることが行われている。   On the other hand, the stave not only protects the furnace body, but also information such as the amount of heat extracted from the stave temperature and cooling water temperature measured by the thermometer installed in the stave body and cooling water piping, and the cooling water temperature of water supply and drainage. (Hereinafter referred to as “thermometer information”), the blast furnace status can be estimated. Therefore, an operation method guideline is obtained from these thermometer information.

例えば、特許文献４には、炉壁部の付着物が厚くなるとステーブ給排水温度差が小さくなるので、ステーブ給排水温度差が管理値以下になった時に、装入方法を調整する高炉操業方法が開示されている。また、特許文献５には、高炉の融着帯形状を把握して管理するために、高炉炉壁の高さ方向のステーブ温度を使用する高炉の操業方法が開示されている。融着帯形状と関係の深い測定値情報として、高炉炉壁部の高さ方向の炉内圧力や半径方向のガス分析ゾンデ情報も併記されているが、高炉炉壁部の高さ方向のステーブ温度は、最も有用な情報として記載されている。   For example, Patent Document 4 discloses a blast furnace operation method that adjusts the charging method when the stave water supply / drainage temperature difference becomes less than the control value because the stave water supply / drainage temperature difference becomes smaller as the deposit on the furnace wall becomes thicker. Has been. Patent Document 5 discloses a method of operating a blast furnace that uses a stave temperature in the height direction of the blast furnace wall in order to grasp and manage the cohesive zone shape of the blast furnace. As measured value information closely related to the shape of the cohesive zone, the furnace pressure in the height direction of the blast furnace wall and gas analysis sonde information in the radial direction are also shown, but the stave in the height direction of the blast furnace wall is also shown. Temperature is listed as the most useful information.

ところで、現在の高炉操業の課題として還元材比の低減が挙げられる。地球温暖化現象の要因となる二酸化炭素の排出量を削減するためには、銑鉄生成必要エネルギーである高炉還元材比を低下させることが有効である。そして、高炉還元材比を低下させるためには、高炉炉内からの抜熱量を低減し、高炉反応効率を高める装入方法調整を実施する必要がある。   By the way, reduction of the reducing material ratio can be cited as a problem of current blast furnace operation. In order to reduce the amount of carbon dioxide emissions that cause global warming, it is effective to reduce the ratio of blast furnace reducing material, which is the energy required for pig iron production. In order to reduce the blast furnace reducing material ratio, it is necessary to adjust the charging method to reduce the amount of heat removed from the blast furnace furnace and increase the blast furnace reaction efficiency.

しかしながら、特許文献４や５に開示されたような、温度計情報に基づいた装入方法の調整においては、装入物の分布制御を介して、炉壁側のガス流れを変更させる必要がある。ところが、そもそも装入方法は、低還元材比で操業すべく、高炉炉内反応効率が最適となるよう調整された装入物分布の制御方法が採用されている。したがって、上記のようなステーブの温度計情報に基づいた装入方法の調整を行うことは、その方法に基づき高炉炉内反応効率が最適となるよう調整された装入物分布を一旦崩す必要がある。また、ステーブの温度計情報では温度測定値により装入方法の調整量が異なるため、操作タイミングが難しい。さらに、装入方法の調整は炉上部からの操作であるので、ステーブ温度が垂直方向で不均一な場合には、不必要な部位に悪影響を及ぼす可能性がある。   However, in the adjustment of the charging method based on thermometer information as disclosed in Patent Documents 4 and 5, it is necessary to change the gas flow on the furnace wall side through the distribution control of the charged material. . However, in the first place, the charge distribution control method adjusted so that the reaction efficiency in the blast furnace is optimized is employed so as to operate at a low reducing material ratio. Therefore, adjustment of the charging method based on the thermometer information of the stave as described above requires that the charge distribution adjusted to optimize the reaction efficiency in the blast furnace based on that method needs to be temporarily broken. is there. Moreover, in the thermometer information of a stave, since the adjustment amount of a charging method changes with temperature measured values, operation timing is difficult. Furthermore, since the adjustment of the charging method is an operation from the top of the furnace, if the stave temperature is not uniform in the vertical direction, it may adversely affect unnecessary parts.

よって、低還元材比操業を安定的に維持する為には、最適な反応効率を生み出す装入物分布をできる限り崩さない、すなわち装入方法調整をあまり必要としない方法が望ましい。   Therefore, in order to stably maintain the operation with a low reducing material ratio, a method that does not disturb the charge distribution that generates the optimum reaction efficiency as much as possible, that is, does not require much adjustment of the charging method is desirable.

しかしながら、特許文献２に開示された方法は、炉壁部付着物が過剰に生成した時に機械的に除去する方法であるので、付着物を除去した際にガス流れが変化し、還元効率の低下、還元材比の上昇を招くおそれがある。   However, since the method disclosed in Patent Document 2 is a method of mechanically removing the deposit on the furnace wall when it is excessively generated, the gas flow changes when the deposit is removed, resulting in a reduction in reduction efficiency. There is a risk that the ratio of the reducing material will increase.

また、特許文献３に記載された緩冷却ステーブ採用は、居包み煉瓦を採用しており、耐火物である煉瓦を使用する以上、その損耗を完全に防止することはできない。近年の高炉寿命は延長する傾向にあるため、この耐火物である煉瓦の寿命が相対的に短くなり、耐火物の損耗影響なしに使用することは困難である。このため、居包み煉瓦を用いたステーブを操業途中で取り替える必要が生じる可能性がある。このような作業がコスト・生産量に大きく悪い方向に変動を与えることはいうまでもなく、このような背景から、居包み煉瓦を採用しないステーブが採用されてきている（例えば特許文献６参照。)。
特開平１１−２２９０１２号公報 特開平５−１１７７２９号公報 特開平８−６０２１３号公報 特開平８−１５７９１２号公報 特開平３−１７０６０７号公報 特開２００２-１２９２１５号公報 Moreover, the slow cooling stave adoption described in patent document 3 employs a wrapping brick, and the wear cannot be completely prevented as long as a brick that is a refractory is used. Since the blast furnace life in recent years tends to be extended, the life of the brick, which is the refractory, becomes relatively short, and it is difficult to use it without the influence of wear of the refractory. For this reason, it may be necessary to replace the stave using the wrapping bricks during operation. Needless to say, such work greatly fluctuates the cost and production amount in a bad direction. From such a background, a stave that does not use the enclosing brick has been adopted (for example, see Patent Document 6). ).
Japanese Patent Application Laid-Open No. 11-229012 Japanese Patent Laid-Open No. 5-117729 JP-A-8-60213 JP-A-8-157912 Japanese Patent Laid-Open No. 3-170607 JP 2002-129215 A

そこで、本発明は、反応効率が最適となるように調整された装入方法を変更することなく、且つ、コスト・生産に大きく変動を与える設備変更なしに、低還元材比操業を達成する高炉の操業方法を提供することを目的とする。 Accordingly, the present invention provides a blast furnace that achieves a low reductant ratio operation without changing the charging method adjusted to optimize the reaction efficiency and without changing the equipment that greatly changes the cost and production. The purpose is to provide a method of operation.

本発明者は、上記問題点を踏まえ、種々の操業実績を解析した結果、炉壁からの抜熱量が変動する場合には、高炉最下部ステーブ部位の温度変動が起因となって起こることを見出した。そしてこの知見に基づいて完成された本発明は、ステーブに供給するステーブ冷却水の温度を上下限管理することにより付着物の厚さを調整することを要旨とする。すなわち、付着物を過剰に生成させないように冷却水温度を下限管理し、還元材比の上昇を招かない程度の適切な厚みの付着物を生成させるための冷却水温度の上限管理をするものである。   As a result of analyzing various operational results based on the above problems, the present inventor has found that when the amount of heat extracted from the furnace wall fluctuates, it is caused by temperature fluctuations in the blast furnace bottom stave part. It was. The gist of the present invention completed based on this finding is to adjust the thickness of the deposit by controlling the upper and lower limits of the temperature of the stave cooling water supplied to the stave. In other words, the lower limit of the cooling water temperature is controlled so as not to generate excessive deposits, and the upper limit of the cooling water temperature is controlled to generate deposits with an appropriate thickness that does not increase the reducing material ratio. is there.

具体的には、本発明は次のとおりである。
（１）高炉の周縁部に配置される鉄皮およびその内側に配置される冷却機構からなるステーブと、当該ステーブに冷却水を供給するための冷却水供給系および当該ステーブの内部を通過した冷却水を排出するための冷却水排出系を有するステーブ冷却系とを用いる高炉の操業方法であって、前記冷却水供給系から前記ステーブに供給される冷却水の温度を所定の範囲に制御することにより前記高炉内の炉壁部に形成される付着物の厚みを調整することを特徴とする高炉の操業方法。 Specifically, the present invention is as follows.
(1) Stave comprising an iron skin arranged at the peripheral edge of the blast furnace and a cooling mechanism arranged inside thereof, a cooling water supply system for supplying cooling water to the stave, and cooling that has passed through the stave A method for operating a blast furnace using a stave cooling system having a cooling water discharge system for discharging water, wherein the temperature of the cooling water supplied from the cooling water supply system to the stave is controlled within a predetermined range. A method of operating a blast furnace , characterized in that the thickness of deposits formed on a furnace wall portion in the blast furnace is adjusted by the above.

（２）前記冷却水供給系から前記ステーブに供給される冷却水が最下部ステーブに供給される上記（１）記載の高炉の操業方法。 (2) the method of operating the cooling water supplied to the staves from the cooling water supply system blast furnace (1) Symbol placement supplied to the bottom staves.

（３）前記ステーブ冷却系は、前記冷却水排出系からの冷却水を熱交換器によって冷却して前記冷却水供給系の冷却水として使用する循環型の冷却系であって、前記冷却供給系から前記ステーブに供給される冷却水の温度の制御は、前記熱交換器の冷却媒体流量を制御する制御弁を用いて当該冷却媒体流量を調整することにより行われる上記（１）または（２）に記載の高炉の操業方法。 ( 3 ) The stave cooling system is a circulation type cooling system that cools the cooling water from the cooling water discharge system with a heat exchanger and uses the cooling water as cooling water for the cooling water supply system. The temperature of the cooling water supplied to the stave is controlled by adjusting the flow rate of the cooling medium using a control valve that controls the flow rate of the cooling medium of the heat exchanger (1) or (2) The operation method of the blast furnace as described in 4.

（４）前記冷却供給系から前記ステーブに供給される冷却水の温度の制御が、２６〜３１℃の範囲で行われる上記（１）から（３）のいずれかに記載の高炉の操業方法。
( 4 ) The method for operating a blast furnace according to any one of (1) to ( 3 ), wherein the temperature of the cooling water supplied from the cooling supply system to the stave is controlled in a range of 26 to 31 ° C.

本発明によれば、最下部ステーブに供給する冷却水温の下限を管理することで付着物を過剰な生成を抑制し、同冷却水温の上限を管理することで還元材の上昇を招かない程度の適切な量の付着物を炉内壁に生成させることを実現している。このため、コスト・生産に大きく変動を与える設備変更なしに炉壁熱負荷を制御することが可能である。したがって、本発明に係る管理方法では、最適反応効率となるよう調整された装入方法を変更することなく、低還元材比操業の達成に大きく寄与することが実現される。   According to the present invention, by controlling the lower limit of the cooling water temperature supplied to the lowermost stave, excessive generation of deposits is suppressed, and by controlling the upper limit of the cooling water temperature, the reducing material is not increased. An appropriate amount of deposits is generated on the inner wall of the furnace. For this reason, it is possible to control the furnace wall heat load without changing the equipment that greatly changes the cost and production. Therefore, in the management method according to the present invention, it is realized to greatly contribute to the achievement of the operation with a low reducing material ratio without changing the charging method adjusted to achieve the optimum reaction efficiency.

本発明において冷却水供給系からステーブに供給される冷却水の温度（以下、「ステーブ給水温度」ともいう。）を所定の範囲に制御する理由について、図面を参照しつつ、以下詳細に説明する。   In the present invention, the reason why the temperature of the cooling water supplied to the stave from the cooling water supply system (hereinafter also referred to as “stave water supply temperature”) is controlled within a predetermined range will be described in detail below with reference to the drawings. .

図１に本発明に係る管理方法を実施する前の高炉ステーブ温度、冷却水の給水温度・炉壁抜熱量状況を示したグラフである。この実施前の状況では、最下部ステーブへの給水温度は管理されていなかったため、抜熱量変動により（ステーブ排出温度が変化したことに基づき）ステーブ給水温度が変化するとともに、冷却媒体である海水の温度変化によってもステーブ給水温度が変動していた。   FIG. 1 is a graph showing the blast furnace stave temperature, cooling water supply temperature, and furnace wall heat removal status before the management method according to the present invention is implemented. In this situation before the implementation, the water supply temperature to the lowermost stave was not controlled, so the change in the amount of heat removal (based on the change in the discharge temperature of the stave) caused the change in the water supply temperature of the stave and the seawater that was the cooling medium. Stave water supply temperature fluctuated due to temperature change.

この条件で行われた種々の操業実績を解析した結果、高炉最下部ステーブの温度が変動を開始すると、その後、その変動が上部側ステーブに伝播し、結果的に高炉ステーブによる炉壁抜熱量（ステーブ給排水温度差）が上昇する現象を見出した。   As a result of analyzing the results of various operations performed under these conditions, when the temperature of the blast furnace bottom stave starts to fluctuate, then the fluctuation propagates to the upper stave, resulting in the amount of heat removed from the furnace wall by the blast furnace stave ( We found a phenomenon in which the temperature difference between the stave and the drainage increased.

この現象に基づき、本発明者は、熱交換器の冷却媒体の流量を変化させて最下部ステーブへの給水温度を制御すれば、適切な厚さの付着物を炉内壁に形成することが可能であるとの着想を得た。そこで、ステーブ給水温度T3とステーブ表面温度T1・ステーブ表面付着物厚みLcの関係を求めるために、図３の概要図と下記（１）〜（３）式に示すような簡便な試算を行った。   Based on this phenomenon, the present inventor can form a deposit having an appropriate thickness on the furnace inner wall by changing the flow rate of the cooling medium of the heat exchanger to control the feed water temperature to the lowermost stave. I got the idea of being. Therefore, in order to obtain the relationship between the stave water supply temperature T3, stave surface temperature T1, and stave surface deposit thickness Lc, a simple trial calculation as shown in the schematic diagram of FIG. 3 and the following equations (1) to (3) was performed. .

Figure 0005353118
Figure 0005353118

ここで、Q：ステーブ抜熱量、λ：ステーブ熱伝導率、L：ステーブ厚み、α：冷却配管熱伝達率、S：冷却配管表面積、Cw：水の比熱、T1：ステーブ表面温度、T2：冷却配管表面温度、T3：ステーブ給水温度、T4：ステーブ排水温度、およびW：ステーブからの排水量である。   Where, Q: Stave heat removal, λ: Stave thermal conductivity, L: Stave thickness, α: Cooling pipe heat transfer coefficient, S: Cooling pipe surface area, Cw: Specific heat of water, T1: Stave surface temperature, T2: Cooling Piping surface temperature, T3: Stave water supply temperature, T4: Stave drain temperature, and W: Waste water volume from the stave.

Figure 0005353118
Figure 0005353118

ここで、Lc：ステーブ表面付着物厚み、kc：付着物熱伝導率、Tg：炉内温度、Q1：単位表面積あたりのステーブ抜熱量、Dp：炉壁近傍粒子径、およびkew：炉壁近傍充填層熱伝導率である。   Where, Lc: Stave surface deposit thickness, kc: Deposit thermal conductivity, Tg: Furnace temperature, Q1: Stave heat removal per unit surface area, Dp: Particle diameter near furnace wall, and kew: Fill near furnace wall Layer thermal conductivity.

式（１）に示されるステーブ抜熱量の関係式を展開することにより、ステーブ給水温度T3とステーブ表面温度T1の関係を表す（２）式を求めることができる。また、炉内付着物厚みLcとステーブ表面温度T1の関係式（３）を用いることにより、（２）式で得られたステーブ表面温度T1から付着物厚みLcを求めることができる。   By developing the relational expression of the amount of heat removed from the stave expressed by the expression (1), the expression (2) representing the relation between the stave water supply temperature T3 and the stave surface temperature T1 can be obtained. Further, by using the relational expression (3) between the in-furnace deposit thickness Lc and the stave surface temperature T1, the deposit thickness Lc can be obtained from the stave surface temperature T1 obtained by the formula (2).

表１にステーブ抜熱の計算前提を示す。   Table 1 shows the calculation assumptions for stave heat removal.

Figure 0005353118
Figure 0005353118

図４に、ステーブ給水温度T3を変化させた場合の、ステーブ表面温度T1とステーブ表面付着物厚みLcの計算結果を示す。また、前述のように、炉内に存在する溶銑・スラグの溶融温度は９００〜１２００℃であるから、この温度域まで加熱されると、付着物も溶融し、炉壁部から脱落してしまう。本計算結果によれば、ステーブ給水温度が４７℃以上の場合には、ステーブ表面温度T1が上昇してこの温度領域となるため、炉内壁における付着物の形成が困難である。したがって、ステーブ給水温度を４７℃以下にすることによりステーブ表面付着物が生成する可能性があることを本計算結果は示唆している。一方、ステーブ給水温度を低下させて２５℃以下にすると、炉壁部の付着物厚みが急上昇する領域になるので、ステーブ給水温度による付着物厚み制御が困難であると推測された。   FIG. 4 shows the calculation results of the stave surface temperature T1 and the stave surface deposit thickness Lc when the stave water supply temperature T3 is changed. Moreover, since the melting temperature of the hot metal / slag existing in the furnace is 900 to 1200 ° C. as described above, when heated to this temperature range, the deposits are also melted and fall off from the furnace wall. . According to this calculation result, when the stave water supply temperature is 47 ° C. or higher, the stave surface temperature T1 rises to be in this temperature range, so that it is difficult to form deposits on the furnace inner wall. Therefore, this calculation result suggests that stave surface deposits may be generated when the stave water supply temperature is set to 47 ° C. or lower. On the other hand, when the stave water supply temperature is lowered to 25 ° C. or lower, the deposit thickness on the furnace wall portion becomes a region where the deposit thickness rapidly rises, so it has been estimated that it is difficult to control the deposit thickness by the stave water supply temperature.

よって、冷却水供給系からステーブに供給される冷却水の温度を所定の範囲に制御して炉内壁の温度を所定の範囲に制御することによって、溶解炉内の炉壁部に形成される付着物の厚みを所定の範囲に調整可能であることが本計算結果に基づき理解される。このように付着物の厚みが所定の範囲に調整されることで炉からステーブへの抜熱量も所定の範囲に制御され、炉内の反応効率の変動を抑制することが実現される。また、付着物の厚みを調整するために炉内装入量を調整したり付着物を機械的に除去したりする必要もないため、生産性が低下しにくい。   Therefore, the temperature of the cooling water supplied to the stave from the cooling water supply system is controlled within a predetermined range, and the temperature of the furnace inner wall is controlled within the predetermined range, thereby forming an attachment formed on the furnace wall portion in the melting furnace. It is understood based on the calculation result that the thickness of the kimono can be adjusted within a predetermined range. In this way, the amount of heat removed from the furnace to the stave is also controlled to a predetermined range by adjusting the thickness of the deposit to a predetermined range, and it is possible to suppress fluctuations in reaction efficiency in the furnace. Further, since it is not necessary to adjust the furnace interior charge or to remove the deposits mechanically in order to adjust the thickness of the deposits, the productivity is not easily lowered.

なお、以上の説明では、冷却されて最下部ステーブに供給される冷却水の水量は一定にされている。また、最上部ステーブから排出された冷却水が熱交換器によって冷却されて最下部ステーブに供給される冷却水となる、循環型の冷却系によってステーブの冷却を行っているが、最下部ステーブに冷却水を供給する冷却水供給系とステーブ内部を通過した冷却水が排水される冷却水排水系とが閉じていない構成であってもよい。ただし、閉じている循環型であるほうが環境保護の観点から好ましい。さらに、冷却水供給系からの冷却水が供給されるステーブは最下部に位置するステーブでなくてもよいが、炉内では羽口に近い下部のほうが温度が高い場合が多いため、最下部から供給することが好ましい。   In the above description, the amount of cooling water that is cooled and supplied to the lowermost stave is constant. In addition, the cooling water discharged from the uppermost stave is cooled by a heat exchanger and becomes cooling water supplied to the lowermost stave, and the stave is cooled by a circulation type cooling system. The cooling water supply system that supplies the cooling water and the cooling water drainage system that drains the cooling water that has passed through the stave may not be closed. However, the closed circulation type is preferable from the viewpoint of environmental protection. Furthermore, the stave to which cooling water from the cooling water supply system is supplied does not have to be the stave located at the bottom, but in the furnace, the temperature near the tuyere is often higher. It is preferable to supply.

以下に、上記の計算結果を検証するために行った実験結果を示す。
図２に示される構成のステーブおよび冷却システムを有する炉容積５３７０m３の高炉に、塊コークスおよび鉱石（塊鉱石および焼結鉱の混合体）が交互に積層されるように装入し、高炉下方の羽口から還元剤としての微粉炭を含有する酸素富化大気の熱風を供給して、上記の装入物を加熱した。ここで、図２に示される冷却システムが図７で示される一般的な冷却システムと異なる点は、ステーブ給水温度の制御が可能なように、冷却媒体制御弁が設けられていることである。この制御弁を制御することにより、冷却媒体流量を調整し、最下部ステーブに供給される給水温度は、冷却媒体温度以上の範囲で任意に制御することが可能とされている。 The following shows the results of experiments conducted to verify the above calculation results.
A blast furnace having a furnace volume of 5370 m 3 having the stave and cooling system shown in FIG. The above charge was heated by supplying hot air of an oxygen-enriched atmosphere containing pulverized coal as a reducing agent from the tuyere of No. 1. Here, the cooling system shown in FIG. 2 is different from the general cooling system shown in FIG. 7 in that a cooling medium control valve is provided so that the stave water supply temperature can be controlled. By controlling this control valve, the coolant flow rate is adjusted, and the feed water temperature supplied to the lowermost stave can be arbitrarily controlled within a range equal to or higher than the coolant temperature.

必要に応じて高炉の炉頂から塊コークスおよび鉱石を追加しつつ、操業開始初期はステーブ給水温度の管理を行わない状態で操業し、本実験期間中は、冷却媒体制御弁を調整して給水温度を管理しながら高炉を操業させた。そして、この操業期間を通じて、最下部ステーブから排出される冷却水の温度変化を測定して、最下部ステーブにおける単位面積当たりの抜熱量について１日の操業における平均値を毎日算出した。また、高炉の炉内壁を流動するガス流れを測定して、１日の操業における炉壁流の変動回数を毎日計測した。   If necessary, add lump coke and ore from the top of the blast furnace and operate without the management of the stave water temperature at the beginning of the operation, and adjust the cooling medium control valve to supply water during the experiment. The blast furnace was operated while controlling the temperature. And the temperature change of the cooling water discharged | emitted from a lowest stave was measured through this operation period, and the average value in the operation of one day was calculated every day about the amount of heat removal per unit area in a lowermost stave. Moreover, the gas flow which flows through the furnace inner wall of a blast furnace was measured, and the fluctuation | variation frequency of the furnace wall flow in one day operation was measured every day.

上記の計測の結果が図５および図６であり、図５上は最下部ステーブ抜熱量のステーブ給水温度依存性を、図５下はガス流れ変動回数のステーブ給水温度依存性を示すグラフである。また、図６上は、追加で装入した塊コークスおよび鉱石のそれぞれの１日あたりの装入量に基づき算出した還元材比の操業期間における推移を示すグラフであり、図６下は、ステーブ給水温度の１日の操業における平均値の操業期間における推移を示すプロットである。   FIG. 5 and FIG. 6 show the results of the above measurement. FIG. 5 is a graph showing the dependency of the heat removal from the bottom stave on the stave water supply temperature, and FIG. . Moreover, the upper part of FIG. 6 is a graph showing the transition of the reductant ratio calculated based on the charged amount per day of the lump coke and ore added additionally in the operation period, and the lower part of FIG. It is a plot which shows transition in the operation period of the average value in the daily operation of feed water temperature.

図５に示されるように、ステーブ給水温度が２６〜３１℃の範囲に管理されている場合には、ステーブ抜熱量は３０ｋｃａｌ／Ｈ以下に抑制されることが確認された。また、この場合には、炉壁流動回数は６回／日以下となり、特に２７〜３０℃の範囲で管理されている場合には炉へ着流動回数をおおむね２回／日以下となった。さらに、ステーブ給水温度が２６〜３１℃の範囲に管理されている場合には、還元材比も、ばらつきはあるもののおおむね４８０ｋｇ／ｐｔ以下に抑制することができた。   As shown in FIG. 5, it was confirmed that the amount of heat removed from the stave was suppressed to 30 kcal / H or less when the stave water supply temperature was controlled in the range of 26 to 31 ° C. In this case, the flow rate of the furnace wall was 6 times / day or less, and particularly when the temperature was controlled in the range of 27 to 30 ° C., the flow rate of the furnace wall was approximately 2 times / day or less. Furthermore, when the stave water supply temperature was controlled in the range of 26 to 31 ° C., the reducing material ratio was also able to be suppressed to approximately 480 kg / pt or less, although there were variations.

これに対し、ステーブ給水温度が３１℃以上の場合には、ステーブ抜熱量が上昇して３０ｋｃａｌ／Ｈを越えるときが多くなり、その結果、還元材比がその平均値として４９０ｋｇ／ｐｔ程度となったり、炉壁流動回数が３回／日以上となる日が多くなったりするなど、高炉操業の効率や安定性が低下することが確認された。   On the other hand, when the temperature of the water supply to the stave is 31 ° C. or higher, the amount of heat removed from the stave increases and often exceeds 30 kcal / H. As a result, the reducing material ratio is about 490 kg / pt as an average value. It has been confirmed that the efficiency and stability of blast furnace operation decline, such as the number of times the furnace wall flows 3 times / day or more.

また、ステーブ給水温度が２６℃以下の場合には、抜熱量が低下する傾向が確認され、このため形成された過剰な付着物に起因すると思われるガス流れ変動が増大し、安定な生産の維持が困難になる結果が得られた。   In addition, when the stave water supply temperature is 26 ° C. or less, a tendency for the amount of heat removal to decrease is confirmed. For this reason, gas flow fluctuations that are thought to be caused by excessive deposits formed increase, and stable production is maintained. The result is difficult.

本発明における炉壁熱負荷（ステーブ給排水温度差）上昇時に最下部ステーブ温度より変動開始する状態を示す図である。It is a figure which shows the state which starts a fluctuation | variation from the lowest stave temperature at the time of the furnace wall thermal load (stave water supply / drainage temperature difference) rise in this invention. 本発明におけるステーブ冷却水配管系統（ステーブ冷却系）の構成を概念的に示すブロック図である。It is a block diagram which shows notionally the structure of the stave cooling water piping system (stave cooling system) in this invention. ステーブ給水温度とステーブ表面温度との関係を求めるためのモデルを示す概要図である。It is a schematic diagram which shows the model for calculating | requiring the relationship between stave water supply temperature and stave surface temperature. ステーブ給水温度とステーブ表面温度・炉内付着物厚みとの関係を表すグラフである。It is a graph showing the relationship between stave water supply temperature, stave surface temperature, and the deposit thickness in a furnace. ステーブ給水温度と下部ステーブ抜熱量（上グラフ）・炉壁ガス流れ変動（下グラフ）との関係を表すグラフである。It is a graph showing the relationship between a stave water supply temperature and the amount of heat removal from a lower stave (upper graph) and furnace wall gas flow fluctuation (lower graph). ステーブ給水温度（上グラフ）および還元材比（下グラフ）の操業期間中の推移を示すグラフである。It is a graph which shows transition during the operation period of stave water supply temperature (upper graph) and reducing material ratio (lower graph). 従来技術に係るステーブ冷却水配管系統（ステーブ冷却系）の構成を概念的に示すブロック図である。It is a block diagram which shows notionally the structure of the stave cooling water piping system (stave cooling system) which concerns on a prior art.

Claims (4)

高炉の周縁部に配置される鉄皮およびその内側に配置される冷却機構からなるステーブと、当該ステーブに冷却水を供給するための冷却水供給系および当該ステーブの内部を通過した冷却水を排出するための冷却水排出系を有するステーブ冷却系とを用いる高炉の操業方法であって、
前記冷却水供給系から前記ステーブに供給される冷却水の温度を所定の範囲に制御することにより前記高炉内の炉壁部に形成される付着物の厚みを調整することを特徴とする高炉の操業方法。 A stave consisting of an iron skin arranged at the peripheral edge of the blast furnace and a cooling mechanism arranged inside thereof, a cooling water supply system for supplying cooling water to the stave, and cooling water passing through the stave are discharged. A blast furnace operating method using a stave cooling system having a cooling water discharge system for
Blast furnace, characterized by adjusting the thickness of the deposits formed furnace wall portion of the blast furnace by controlling the temperature of the cooling water supplied to the staves from the cooling water supply system in a predetermined range Operation method. 前記冷却水供給系から前記ステーブに供給される冷却水が最下部ステーブに供給される請求項１記載の高炉の操業方法。 The method of operation according to claim 1 Symbol placement of blast furnace cooling water supplied to the staves from the cooling water supply system is supplied to the bottom staves. 前記ステーブ冷却系は、前記冷却水排出系からの冷却水を熱交換器によって冷却して前記冷却水供給系の冷却水として使用する循環型の冷却系であって、
前記冷却供給系から前記ステーブに供給される冷却水の温度の制御は、前記熱交換器の冷却媒体流量を制御する制御弁を用いて当該冷却媒体流量を調整することにより行われる請求項１または２に記載の高炉の操業方法。 The stave cooling system is a circulating cooling system that cools cooling water from the cooling water discharge system by a heat exchanger and uses it as cooling water for the cooling water supply system,
The control of the cooling supply system the temperature of the cooling water supplied to the staves, claim 1 is performed by adjusting the cooling medium flow with a control valve for controlling the coolant flow rate of the heat exchanger or The operating method of the blast furnace as described in 2 . 前記冷却供給系から前記ステーブに供給される冷却水の温度の制御が、２６〜３１℃の範囲で行われる請求項１から３のいずれかに記載の高炉の操業方法。 The operation method of the blast furnace in any one of Claim 1 to 3 by which control of the temperature of the cooling water supplied to the said stave from the said cooling supply system is performed in 26-31 degreeC.
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JPH11229012A (en) * 1998-02-13 1999-08-24 Nkk Corp Structure for arranging stave in shaft furnace type metallurgical furnace
JP2001335818A (en) * 2000-05-24 2001-12-04 Nippon Steel Corp Method for cooling furnace bottom in blast furnace
JP3935714B2 (en) * 2001-11-22 2007-06-27 バブコック日立株式会社 Melting furnace cooling system

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