JP3197638B2 - Scale control method in heating furnace - Google Patents
Scale control method in heating furnaceInfo
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- JP3197638B2 JP3197638B2 JP34273592A JP34273592A JP3197638B2 JP 3197638 B2 JP3197638 B2 JP 3197638B2 JP 34273592 A JP34273592 A JP 34273592A JP 34273592 A JP34273592 A JP 34273592A JP 3197638 B2 JP3197638 B2 JP 3197638B2
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- Japan
- Prior art keywords
- heating furnace
- steam
- scale
- fuel
- heating
- Prior art date
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- Furnace Details (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、加熱炉におけるスケー
ル制御方法に関し、さらに詳しくは、連続鋳造機で発生
したスラブ表層の鋳造欠陥を加熱炉でスケールとして除
去し、表面品質が良好な熱延鋼板を得る方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scale control method in a heating furnace, and more particularly, to a hot rolling method which removes casting defects in a slab surface layer generated in a continuous casting machine as a scale in a heating furnace and has a good surface quality. The present invention relates to a method for obtaining a steel sheet.
【０００２】[0002]
【従来の技術】熱間圧延における加熱炉の燃料コストは
大きな割合を占める。このため燃料コストの低減、歩止
向上のために連続鋳造ラインから供給される高温のスラ
ブを短時間の内に加熱炉に装入し、あるいはそのまま圧
延に供するいわゆる直送圧延技術が採用されている。こ
のことは例えば、「日本鉄鋼協会編：第２版わが国にお
ける最近のホットストリップ製造技術（Ｐ．４２〜）Ｓ
６２／８」に詳しく記載されている。この直送圧延を実
施することは、加熱炉へ装入するスラブ温度の高温化に
より燃料原単位の低減となることはもちろんであるが、
加熱炉での加熱時間も大巾に短縮されるので、加熱炉内
で発生するスケールも減小し、製品歩止り向上の面でも
好ましいわけである。2. Description of the Related Art The fuel cost of a heating furnace in hot rolling accounts for a large proportion. Therefore, in order to reduce fuel cost and improve yield, a so-called direct-feed rolling technique is employed in which a high-temperature slab supplied from a continuous casting line is charged into a heating furnace within a short period of time, or is directly subjected to rolling. . This is described in, for example, “Iron and Steel Association, 2nd Edition, Recent Hot Strip Manufacturing Technology in Japan (P.42-) S”
62/8 ". Implementing this direct-feed rolling, of course, reduces the fuel consumption rate by raising the temperature of the slab charged to the heating furnace,
Since the heating time in the heating furnace is greatly reduced, the scale generated in the heating furnace is also reduced, which is preferable in terms of improving product yield.
【０００３】さらに最近の圧延ラインでは生産性向上の
ため圧延速度が速く、その結果加熱炉抽出から圧延完了
までの時間が短くなり、圧延材の圧延中の温度低下量が
小さく、加熱炉の抽出温度も低温となっている。この結
果加熱炉内で発生するスケールは一層減少する。[0003] In recent rolling mills, the rolling speed is high in order to improve the productivity. As a result, the time from the extraction of the heating furnace to the completion of the rolling is shortened. The temperature is also low. As a result, the scale generated in the heating furnace is further reduced.
【０００４】[0004]
【発明が解決しようとする課題】直送圧延化および圧延
速度の高速化に伴う加熱炉抽出温度の低温化により、加
熱炉内で発生するスケールは大巾に減小し、製品歩止り
の向上の面からは好ましい。一方連続鋳造機で鋳造され
たスラブの表層には不可避的に鋳造欠陥が存在する。こ
の鋳造欠陥はスラブ表層への不純物の濃縮、モールドパ
ウダーの巻き込みなどに起因するものである。従来は、
この鋳造欠陥は加熱炉内でスケールとして除去されてい
たが、スケール発生量の低減とともに、加熱炉抽出時に
地鉄側に残ってしまい、圧延後の製品の表面欠陥になる
という問題が発生していた。このため、表面品質要求の
高いものは直送圧延をすることができず、燃料原単位も
悪化していた。With the reduction in the heating furnace extraction temperature accompanying the direct rolling and the higher rolling speed, the scale generated in the heating furnace is greatly reduced, and the product yield is improved. It is preferable from the viewpoint. On the other hand, casting defects are inevitably present in the surface layer of the slab cast by the continuous casting machine. This casting defect is caused by the concentration of impurities in the surface layer of the slab, entrainment of mold powder, and the like. conventionally,
This casting defect was removed as scale in the heating furnace, but with the reduction in the amount of scale generated, it remained on the base iron side when the heating furnace was extracted, causing a problem that it became a surface defect of the product after rolling. Was. For this reason, those requiring high surface quality cannot be directly rolled, and the unit fuel consumption has also deteriorated.
【０００５】加熱雰囲気の制御によりスケールオフ量を
制御することについては、特開昭５３−１４０２１２号
公報に、雰囲気中の酸素濃度を調整する技術が開示され
ているが、加熱バーナの空燃比の調整では、酸素濃度の
調整範囲が狭く十分なスケールオフ量が得られない。For controlling the scale-off amount by controlling the heating atmosphere, Japanese Patent Application Laid-Open No. 53-140212 discloses a technique for adjusting the oxygen concentration in the atmosphere. In the adjustment, the adjustment range of the oxygen concentration is narrow, and a sufficient scale-off amount cannot be obtained.
【０００６】[0006]
【課題を解決するための手段】発明者らは、前記スラブ
の鋳造欠陥の分布を調査した。その結果、鋳造欠陥はス
ラブ表層から０．５ｍｍの位置までに集中していること
を確認した。つまり、加熱炉内で表層０．５ｍｍの部分
をスケールとして除去することができれば、前記問題点
を解決することができるわけである。さらに鉄の酸化
（スケールの発生）は酸素雰囲気よりも、水蒸気雰囲気
の方が促進されるということを実験により確認した。Means for Solving the Problems The present inventors have investigated the distribution of casting defects in the slab. As a result, it was confirmed that the casting defects were concentrated at a position 0.5 mm from the surface of the slab. That is, if the portion of the surface layer of 0.5 mm can be removed as a scale in the heating furnace, the above problem can be solved. Further, it was confirmed by experiments that oxidation of iron (generation of scale) was promoted in a steam atmosphere rather than an oxygen atmosphere.
【０００７】上記２点の結果から短時間の加熱時間であ
っても、加熱炉内の雰囲気を加熱時間と加熱温度に見合
った適切な露点に調整することにより、スラブの鋳造欠
陥をスケールとして除去することができ、良好な製品表
面品質が得られることを見出したわけである。そこで加
熱炉内のスケール生成量を適正に定めるために燃料の組
成、燃料流量及び燃焼用空気流量に基いて必要な水分投
入量を演算し、炉体に設けた投入口からこの水分を投入
し、所定の露点にすることによりスケールオフ量を制御
可能としたものである。すなわち本発明は熱間圧延用ス
ラブを加熱する加熱炉内の必要水蒸気濃度を設定し、こ
れよりも燃焼ガス中の水蒸気濃度が小さい場合に不足す
る水蒸気量を、燃料組成、燃料流量及び燃焼用空気流量
に基いて演算設定し、該演算設定された量の水蒸気を前
記加熱炉に設けた水蒸気投入口から吹き込むことを特徴
とする加熱炉におけるスケール制御方法である。From the results of the above two points, even when the heating time is short, the casting defect of the slab is removed as a scale by adjusting the atmosphere in the heating furnace to an appropriate dew point corresponding to the heating time and the heating temperature. And that good product surface quality can be obtained. Therefore, in order to properly determine the scale generation amount in the heating furnace, the required water input amount is calculated based on the fuel composition, the fuel flow rate, and the combustion air flow rate, and this water is input from the input port provided in the furnace body. The scale-off amount can be controlled by setting a predetermined dew point. That is, the present invention sets the required concentration of water vapor in the heating furnace for heating the slab for hot rolling, this
When the water vapor concentration in the combustion gas is lower than that, the amount of water vapor that is insufficient is calculated and set based on the fuel composition, the fuel flow rate, and the combustion air flow rate, and the calculated amount of water vapor is provided in the heating furnace. A scale control method in a heating furnace, wherein the scale is blown from a steam inlet.
【０００８】[0008]
【作用】図１に加熱時間、加熱温度とスケールオフ量
０．５ｍｍを達成するのに必要な露点Ｗの調査結果を示
す。これを式で現すと Ｗ＝５．８５×１０5 ／（Ｔ＋２７３）−１．５Ｈ＋
６．３×１０-3Ｈ2 −２９４ ただし Ｗ：露点（℃） Ｔ：加熱温度（℃） Ｈ：加熱時間（ｈｒ） となる。つまり、この露点Ｗ以上に加熱炉雰囲気の露点
を調整することにより、鋳造欠陥の集中するスラブ表層
から０．５ｍｍまでの深さの範囲は加熱炉でスケールオ
フされ、良好な表面品質の製品の製造が可能となる。露
点Ｗに相当する水蒸気濃度ＸH2O,1 は ＸH2O,1 ＝｛７．０２×（Ｗ＋２７３．１５）0.105 −１２．０８｝9.52 ［％］ …（１） 一方燃料の燃焼ガス中の水蒸気濃度ＸH2O,2 を燃料の組
成とバーナの空気化で表すとFIG. 1 shows the results of investigation on the heating time, the heating temperature and the dew point W required to achieve the scale-off amount of 0.5 mm. This can be expressed by the following equation: W = 5.85 × 10 5 /(T+273)−1.5H+
6.3 × 10 −3 H 2 -294 where W: dew point (° C.) T: heating temperature (° C.) H: heating time (hr) In other words, by adjusting the dew point of the heating furnace atmosphere above the dew point W, the range of the depth from the slab surface layer where the casting defects are concentrated to 0.5 mm is scaled off by the heating furnace, and a product having good surface quality is obtained. Manufacturing becomes possible. The water vapor concentration X H2O, 1 corresponding to the dew point W is X H2O, 1 = {7.02 × (W + 273.15) 0.105 -12.08} 9.52 [%] (1) On the other hand, the water vapor concentration in the combustion gas of the fuel X H2O, 2 is expressed by fuel composition and burner aeration.
【０００９】[0009]
【数１】 (Equation 1)
【００１０】ただし ｍ：空気比 ＸH2：燃料ガス中のＨ2 濃度 Ｘｃ：燃料ガス中の炭化水素Ｃp Ｈqの濃度 ｐ，ｑ：炭化水素Ｃp Ｈqの添字 ＸN2：：燃料ガス中のＮ2 濃度 従って必要な水蒸気濃度ＸH2O,1よりも燃焼ガス中の水
蒸気濃度ＸH20,2 が小さい場合に不足する水蒸気量Ｑ
H2Oは燃料の量をＱfとすれば ＱH2O ＝ＱfＧo ｍ（ＸH2O,1 −ＸH20,2 ）／１００ ［Ｎｍ 3 ／Ｈ］ …（２） であるからこの水蒸気（水分）量を炉体に設けた投入口
から吹込むように設定することにより必要な露点Ｗ1と
することが可能となり、安定して鋳造欠陥をスケールと
して除去できるようになる。また加熱炉の制御帯毎に上
記制御を行うことにより、加熱時間の変更加熱炉設定炉
温を変更した場合であっても必要なスケールオフ量を達
成することが可能となる。Where m: air ratio X H2 : concentration of H 2 in fuel gas Xc: concentration of hydrocarbon C p H q in fuel gas p, q: suffix of hydrocarbon C p H q X N2 :: fuel gas steam amount Q insufficient when N 2 concentration therefore required steam concentration X H2 O, less water vapor concentration X H20,2 in the combustion gas than 1 in
If H2O is the amount of fuel and Q f Q H2O = Q f G o m (X H2O, 1 -X H20,2) / 100 [Nm 3 / H] ... (2) a is from this water vapor (moisture) the amount it is possible to make the dew point W 1 required by setting the blow useless from inlet provided in the furnace body, comprising a stable casting defects can be removed as a scale. Further, by performing the above-described control for each control zone of the heating furnace, it becomes possible to achieve the necessary scale-off amount even when the heating time is changed and the heating furnace setting furnace temperature is changed.
【００１１】[0011]
【実施例】本発明の効果を確認するために、２６０ｍｍ
厚のスラブを粗圧延機、仕上圧延機で製品厚３．２ｍｍ
まで熱間圧延し、製品の表面状況を確認した。図２に本
発明を実施したスラブ加熱炉１を示した。スラブ３は装
入口５から炉内に装入され、バーナ２によって加熱され
て抽出口７から排出される。バーナ２には燃焼用空気ブ
ロワ１２からの空気及び燃料２１が送られる。燃料２１
は燃料ガス調整バルブ９によって調整され、その流量は
燃料ガス流量計８によって測定される。燃焼用空気は燃
焼用空気流量弁１１で調整され、燃焼用空気流量計１０
で測定される。バーナ２は炉長方向に等ピツチに設けて
いるので、これらのバーナの間に、炉内の露点を均一に
するために、蒸気投入口４を炉の天井と、炉床の双方に
設置した。EXAMPLE In order to confirm the effect of the present invention, a 260 mm
Thick slabs are processed by a rough rolling mill and a finishing rolling mill to a product thickness of 3.2 mm.
Hot-rolled until the surface condition of the product was confirmed. FIG. 2 shows a slab heating furnace 1 according to the present invention. The slab 3 is charged into the furnace through the charging port 5, heated by the burner 2, and discharged from the extraction port 7. Air and fuel 21 from the combustion air blower 12 are sent to the burner 2. Fuel 21
Is regulated by a fuel gas regulating valve 9, and its flow rate is measured by a fuel gas flow meter 8. The combustion air is regulated by a combustion air flow valve 11 and a combustion air flow meter 10 is provided.
Is measured. Since the burners 2 are provided at equal pitches in the furnace length direction, steam inlets 4 are provided between the burners on both the furnace ceiling and the hearth in order to make the dew point in the furnace uniform. .
【００１２】燃料ガス流量計８、燃焼用空気流量計１０
の測定値は演算装置１６に入力される。演算装置１６は
これらのデータ及び燃料ガス組成２３のデータから所要
の露点を求め、必要水蒸気（水分）投入量を演算し、水
蒸気２２吹込用の水蒸気流量調整バルブ１４を調整す
る。水蒸気流量計１３の測定値は演算装置１６にフィー
ドバックされる。Fuel gas flow meter 8, combustion air flow meter 10
Is input to the arithmetic unit 16. The arithmetic unit 16 obtains a required dew point from these data and the data of the fuel gas composition 23, calculates the required steam (moisture) input amount, and adjusts the steam flow rate adjusting valve 14 for blowing the steam 22. The measured value of the steam flow meter 13 is fed back to the arithmetic unit 16.
【００１３】加熱炉の燃料組成（体積比）、燃料流量及
び燃焼用空気流量を表１に示した。この燃料排ガスの露
点は５６℃である。スラブの加熱条件は、加熱温度１２
００℃、加熱時間３０分で操業した。この条件ではスケ
ール除去を行うために必要な露点は６４℃であるので、
蒸気投入口より、水蒸気を投入して露点を６４℃に調整
した。Table 1 shows the fuel composition (volume ratio), fuel flow rate, and combustion air flow rate of the heating furnace. The dew point of this fuel exhaust gas is 56 ° C. The heating conditions for the slab are as follows:
The operation was performed at 00 ° C. for a heating time of 30 minutes. Under these conditions, the dew point required to remove scale is 64 ° C,
The dew point was adjusted to 64 ° C. by introducing steam from the steam inlet.
【００１４】比較例として、露点以外は同一条件で加
熱、圧延したものを掲げた。この場合露点は水蒸気を投
入しない５６℃の条件で実施した。製品表面品質の調査
結果を表２に示した。露点５６℃で加熱したものでは、
鋳造欠陥に起因する表面欠陥が多発したが、実施例の蒸
気投入方法によって露点を６４℃として加熱した場合に
は欠陥のない良好な表面品質の製品を得ることができ
た。[0014] As a comparative example, one heated and rolled under the same conditions except for the dew point is listed. In this case, the dew point was carried out under the condition of 56 ° C. without introducing steam. Table 2 shows the inspection results of the product surface quality. When heated at a dew point of 56 ° C,
Although many surface defects were caused by casting defects, a product with good surface quality without defects could be obtained when heated with a dew point of 64 ° C. by the steam injection method of the example.
【００１５】[0015]
【表１】 ──────────────────────────────────── Ｈ2 ＣＯ ＣＨ4 Ｎ2 ＣＯ2 Ｃ2 Ｈ4 ２７．４％ １３．２％ １２．０％ ３２．０％ １４．２％ １．２％ ──────────────────────────────────── 燃料流量 燃焼用空気流量 １５，０００ｍ3 ／Ｈ ３６，０００ｍ3 ／Ｈ ────────────────────────────────────[Table 1] ──────────────────────────────────── H 2 CO CH 4 N 2 CO 2 C 2 H 4 27.4% 13.2% 12.0 % 32.0% 14.2% 1.2% ───────────────────────燃料 Fuel flow rate Combustion air flow rate 15,000 m 3 / H 36,000 m 3 / H ─────────────────── ─────────────────
【００１６】[0016]
【表２】 加熱炉露点 加熱炉でのスケー 鋳造欠陥起因の欠陥個数 ルオフ厚 （１ｍ2 当り） ６４℃ ０．５ｍｍ ０ コ／ｍ2 ５６℃ ０．３ｍｍ ５０ コ／ｍ2 なお、上記表１のガス組成は一例であり、水素や炭化水
素を含む場合は前記（２）式を用いることで適用可能で
あり、また他のガス組成の場合は本発明の要旨に応じ
て、不足する水分量を演算によって求め、蒸気量に換算
して水蒸気添加してもよく、ほかの手段により水分量を
添加してもよい。[Table 2] Furnace defect number Ruofu thickness (1 m 2 per) of scale casting defects caused at the dew point heating furnace 6 4 ° C. 0.5 mm 0 co / m 2 56 ° C. 0.3 mm 50 co / m 2 Note that the gas compositions in Table 1 above are merely examples. In the case of containing hydrogen or hydrocarbon, the gas composition can be applied by using the above formula (2). Insufficient water content may be obtained by calculation, converted into steam content, and steam may be added, or water content may be added by other means.
【００１７】[0017]
【発明の効果】本発明は、加熱炉炉体に水蒸気投入口を
設け、燃料組成、燃料流量、燃焼用空気流量から必要な
水蒸気投入量を設定することにより適切な炉内雰囲気露
点にすることができるようになったので、連続鋳造機に
起因する鋳造欠陥を加熱炉内でスケールとして確実に除
去でき、良好な表面品質の製品を製造することが可能と
なった。According to the present invention, a steam inlet is provided in a furnace body of a heating furnace, and a necessary steam input amount is set based on a fuel composition, a fuel flow rate, and a combustion air flow rate, thereby obtaining an appropriate furnace dew point. As a result, casting defects caused by the continuous casting machine can be reliably removed as a scale in the heating furnace, and a product with good surface quality can be manufactured.
【図１】本発明を実施した加熱炉の一例の系統図であ
る。FIG. 1 is a system diagram of an example of a heating furnace embodying the present invention.
【図２】加熱時間、加熱温度と最適な露点の関係を示す
グラフである。FIG. 2 is a graph showing a relationship between a heating time, a heating temperature, and an optimum dew point.
１ 加熱炉 ２ バーナ ３ スラブ ４ 蒸気投入口 ５ 装入口 ６ 煙道 ７ 抽出口 ８ 燃料ガス流
量計 ９ 燃料ガス流量調整バルブ １０ 燃焼用空
気流量計 １１ 燃焼用空気流量弁 １２ 燃焼用空
気ブロワ １３ 水蒸気流量計 １４ 水蒸気流
量調整バルブ １６ 演算装置 ２１ 燃料 ２２ 水蒸気 ２３ ガス組成DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Burner 3 Slab 4 Steam inlet 5 Charging inlet 6 Flue 7 Extraction port 8 Fuel gas flow meter 9 Fuel gas flow control valve 10 Combustion air flow meter 11 Combustion air flow valve 12 Combustion air blower 13 Steam Flow meter 14 Steam flow control valve 16 Arithmetic unit 21 Fuel 22 Steam 23 Gas composition
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉田 邦雄 千葉市中央区川崎町１番地 川崎製鉄株 式会社 千葉製鉄所内 (72)発明者 金田 欣亮 千葉市中央区川崎町１番地 川崎製鉄株 式会社 千葉製鉄所内 (56)参考文献 特開 平５−320757（ＪＰ，Ａ) 特公 昭46−23121（ＪＰ，Ｂ１) (58)調査した分野(Int.Cl.7，ＤＢ名) C21D 1/00 - 11/00 F27D 7/02 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kunio Yoshida 1 Kawasaki-cho, Chuo-ku, Chiba-shi Kawasaki Steel Corp. Inside the Chiba Works (72) Inventor Kinsuke Kinda 1-Kawasaki-cho, Chuo-ku, Chiba Kawasaki Steel Co., Ltd. (56) References JP-A-5-320757 (JP, A) JP-B-46-23121 (JP, B1) (58) Fields investigated (Int. Cl. 7 , DB name) C21D 1 / 00-11/00 F27D 7/02
Claims (1)
必要水蒸気濃度を設定し、これよりも燃焼ガス中の水蒸
気濃度が小さい場合に不足する水蒸気量を、燃料組成、
燃料流量及び燃焼用空気流量に基いて演算設定し、該演
算設定された量の水蒸気を前記加熱炉に設けた水蒸気投
入口から吹き込むことを特徴とする加熱炉におけるスケ
ール制御方法。1. A required steam concentration in a heating furnace for heating a slab for hot rolling is set, and a water vapor concentration in a combustion gas is set higher than the required steam concentration.
Insufficient water vapor when the air concentration is low
A scale control method for a heating furnace, wherein the calculation is performed based on a fuel flow rate and a combustion air flow rate, and the calculated and set amount of steam is blown from a steam inlet provided in the heating furnace.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34273592A JP3197638B2 (en) | 1992-12-22 | 1992-12-22 | Scale control method in heating furnace |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34273592A JP3197638B2 (en) | 1992-12-22 | 1992-12-22 | Scale control method in heating furnace |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06184627A JPH06184627A (en) | 1994-07-05 |
| JP3197638B2 true JP3197638B2 (en) | 2001-08-13 |
Family
ID=18356090
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34273592A Expired - Fee Related JP3197638B2 (en) | 1992-12-22 | 1992-12-22 | Scale control method in heating furnace |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3197638B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5839778B2 (en) * | 2010-04-06 | 2016-01-06 | 新日鐵住金株式会社 | Non-oriented electrical steel sheet with excellent high-frequency iron loss and manufacturing method thereof |
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1992
- 1992-12-22 JP JP34273592A patent/JP3197638B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06184627A (en) | 1994-07-05 |
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