JP2551013B2 - AOD furnace - Google Patents
AOD furnaceInfo
- Publication number
- JP2551013B2 JP2551013B2 JP62181232A JP18123287A JP2551013B2 JP 2551013 B2 JP2551013 B2 JP 2551013B2 JP 62181232 A JP62181232 A JP 62181232A JP 18123287 A JP18123287 A JP 18123287A JP 2551013 B2 JP2551013 B2 JP 2551013B2
- Authority
- JP
- Japan
- Prior art keywords
- furnace
- refining
- tuyere
- brick
- molten steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Description
(産業上の利用分野) 本発明は、合金鋼とくにステンレス鋼に適用されるAO
D精錬法(アルゴン−酸素脱炭法)に用いるAOD炉の改良
に係わり、さらに詳しくは精錬時における溶鋼の対流の
デッドゾーンをなくし、スプラッシュの飛散を減少し、
精錬時間の短縮を可能とするAOD炉に関するものであ
る。 (従来の技術) AOD精錬法は、酸素ガスと共にAr,N2などの不活性ガス
を大気圧下で溶鋼中に吹込むことにより、CO分圧を低下
させCrの酸化損失を抑えながら脱炭を行う方法で、酸素
と不活性ガスの混合ガスは、炉底近くの側壁に設置され
た数本の羽口から吹込まれる。 AOD炉壁耐火物は、初期の段階では粘性が低く浸透が
激しい酸性スラグの浸食を受け、さらに側壁下部の羽口
より炉内溶鋼中に噴射される混合ガスによってスラグと
溶鋼は激しく攪拌され炉壁耐火物表面に激しい摩耗現象
を惹き起す。 加えて大量に吹込まれる混合ガスと溶鋼成分との反応
熱により溶鋼温度は1750℃以上にもなるため、特に羽口
および羽口周辺の耐火れんがの溶損が著しい。 そのため、羽口側炉壁には反対側の出鋼側炉壁にくら
べ、耐火れんがをあらかじめ100〜250mm程度厚く内張す
ることによって対処していた。 (発明が解決しようとする問題点) そもそもAOD精錬法は、O2と不活性ガスの混合比率を
容易に変えることができ、溶鋼中の炭素濃度が高炭素領
域から低炭素領域へと脱炭が進むにしたがってO2比を低
くすることにより脱炭効率を向上させると共に、炉側壁
下部の羽口からのガス吹込みによる強裂な浴攪拌によっ
て迅速かつ効果的な精錬を可能としたことにその特徴が
ある。 しかし、一般的にはこのような優れた特性があるとさ
れているにもかかわらず、AOD精錬の実操業において
は、湯の回りの悪い部分、いわゆるデッドゾーンが発生
するとか、スプラッシュ発生量が多いといった問題点も
指摘されている。 溶鋼対流のデッドゾーン防止は、溶鋼中に吹込む混合
ガス量やO2量を増すことによってもある程度可能ではあ
るが、これらはスプラッシュ量の増加を招くばかりか、
混合ガスのガス量やO2比は前述のように脱炭効率と密接
に関連があるので、単純に増加させることはできない。 そこで本発明者は、AOD炉の形状や耐火れんがの内張
方法等について綿密に調査、検討した結果、AOD炉では
羽口側炉壁と出鋼側炉壁には耐火れんがの内張厚さに前
に述べたような差があるため、炉体の中心と、れんがを
内張した実質的な炉内部の中心すなわち溶鋼の中心とが
ずれていることに着目した。 すなわち、第2図は従来のAOD炉の羽口高さでの横断
面における耐火れんがのライニング状況を示すものであ
り、鉄皮3の内側には焼成マグネシアれんがによる永久
張れんが4が張られ、さらにその内側にマグクロ質ダイ
レクトボンドれんがからなる扇形の内張れんが5が張ら
れている。内張れんが5のうち羽口側炉壁の内張れんが
5(5a)は、前述のような激しい摩耗や高温に備えるた
め、出鋼側内張れんが5(5b)にくらべ、1.5倍程度厚
く内張されている。 また、精錬ガスは羽口れんが2の位置からトイヤによ
り溶鋼中に吹込まれるが、その方向は炉体の中心Cの方
向に向くよう設定されている。 このように従来のAOD炉では、羽口側と出鋼側のライ
ニング厚さが異なり、炉の内側形状が非対称となってい
るにもかからわず、羽口方向が炉体の中心Cを向いてい
るという問題点が明らかとなった。 したがって、精錬ガスは炉内部の溶鋼の中心部よりか
なり手前側に吹込まれることになり、そこを起点に溶鋼
の対流や精錬反応が起るため、出鋼側炉底近傍に反応に
関与しない溶鋼のデッドゾーンができてしまうものと考
えられる。 また、このようなデッドゾーンの発生により、溶鋼の
対流や精錬反応が局部的に起り、吹込まれたガス量に対
して精錬に関与する溶鋼量が少なくなるため、ガス気泡
が粗大化し、脱炭効率が低下すると共にスプラッシュの
発生量も多くなるものと思われる。 (発明の目的) 本発明は上記のような問題点を解決すべくなされたも
のであって、その目的とするところは、溶鋼対流のデッ
ドゾーン発生の防止およびスプラッシュ量の低減、さら
にはこれに基づく製鋼歩留および能率の向上にある。(Industrial field of application) The present invention is applied to alloy steel, especially stainless steel.
D related to improvement of AOD furnace used for refining method (argon-oxygen decarburization method), more specifically, eliminating convection dead zone of molten steel during refining, reducing splash of splash,
The present invention relates to an AOD furnace capable of shortening refining time. (Prior art) The AOD refining method is a method of decarburizing by blowing an inert gas such as Ar and N 2 together with oxygen gas into molten steel at atmospheric pressure to reduce the CO partial pressure and suppress the oxidation loss of Cr. In this method, the mixed gas of oxygen and the inert gas is blown from several tuyere installed on the side wall near the furnace bottom. AOD furnace wall refractory is eroded by acid slag with low viscosity and violent infiltration in the initial stage, and further the slag and molten steel are vigorously stirred by the mixed gas injected into the molten steel in the furnace from the tuyere at the bottom of the side wall. Causes severe wear phenomena on the wall refractory surface. In addition, the molten steel temperature rises to over 1750 ° C due to the heat of reaction between the mixed gas blown in a large amount and the molten steel components, so that the melting loss of the refractory bricks especially at the tuyere and around the tuyere is remarkable. Therefore, in comparison with the tapped side furnace wall on the opposite side, the refractory brick was lined in advance with a thickness of 100 to 250 mm for the tuyere side furnace wall. (Problems to be solved by the invention) In the first place, the AOD refining method can easily change the mixing ratio of O 2 and the inert gas, and the carbon concentration in the molten steel is decarburized from the high carbon region to the low carbon region. The decarburization efficiency was improved by lowering the O 2 ratio as the temperature increased, and rapid and effective refining was enabled by vigorous bath agitation by blowing gas from the tuyere at the bottom of the furnace side wall. It has its characteristics. However, even though it is generally said that such excellent characteristics are present, in the actual operation of AOD refining, a part where the hot water does not go well, that is, a so-called dead zone occurs, or the amount of splash generation is large. Many problems have been pointed out. It is possible to prevent the dead zone of molten steel convection by increasing the amount of mixed gas and the amount of O 2 blown into the molten steel to some extent, but these not only increase the splash amount,
Since the gas amount and O 2 ratio of the mixed gas are closely related to the decarburization efficiency as described above, they cannot be simply increased. Therefore, the present inventor has scrutinized and examined the shape of the AOD furnace and the lining method of the refractory bricks, and as a result, in the AOD furnace, the tuyere side furnace wall and the tapped side furnace wall have a refractory brick lining thickness. Because of the difference as described above, we focused on the fact that the center of the furnace body and the center of the substantial inside of the furnace lined with bricks, that is, the center of the molten steel are deviated. That is, FIG. 2 shows the lining condition of the refractory brick in the cross section at the tuyere height of the conventional AOD furnace, in which the permanent tension brick 4 made of the fired magnesia brick is placed inside the iron shell 3. Further, a fan-shaped lining brick 5 made of magrophilic direct bond brick is laid on the inside thereof. Of the liner bricks 5, the liner bricks 5 (5a) on the tuyere side furnace wall are about 1.5 times thicker than the liner bricks 5 (5b) on the tapped side in order to prepare for the severe wear and high temperatures mentioned above. It is lined. Further, the refining gas is blown into the molten steel from the position of the tuyere brick 2 into the molten steel by the toyers, and the direction thereof is set to face the center C of the furnace body. As described above, in the conventional AOD furnace, the tuyere direction differs from the center C of the furnace body in spite of the fact that the lining thicknesses on the tuyere side and the tapped side are different and the inner shape of the furnace is asymmetrical. The problem of being suitable became clear. Therefore, the refining gas is blown to the front side of the center of the molten steel inside the furnace, and convection of the molten steel and refining reaction occur from that point and do not participate in the reaction near the tapped side furnace bottom. It is considered that a dead zone of molten steel is created. In addition, due to the occurrence of such a dead zone, convection of molten steel and refining reaction locally occur, and the amount of molten steel involved in refining with respect to the amount of gas blown is reduced, resulting in coarse gas bubbles and decarburization. It is expected that the efficiency will decrease and the amount of splash will increase. (Object of the Invention) The present invention has been made to solve the above problems, and an object of the present invention is to prevent the occurrence of a dead zone of molten steel convection and reduce the amount of splash, and further to this. Based on the improvement of steelmaking yield and efficiency.
(問題点を解決するための手段) 本発明は、耐火レンガの内張が非対称となるAOD炉形
状を考慮してなされたもので、AOD炉の精錬ガス吹込み
方向を炉体中心より奥側の溶鋼中心部に向けることによ
って、精錬反応のデッドゾーンをなくし、炉内全体にわ
たる効率的な精錬が円滑に進むようにし、もってガス気
泡が細粒化しスプラッシュ発生量の減少と精錬時間の短
縮を可能としたもので、本発明AOD炉は、炉側壁に設け
た複数の羽口から炉内に吹込まれる精錬用ガスの吹出し
線の交点が、炉体の中心から遠方側にずらした位置にあ
ることを特徴としている。 本発明において、精錬ガスの吹込み方向は必ずしも溶
鋼の中心と完全に一致している必要はなく、炉体形状,
容量,操業条件等を勘案して,炉体中心との距離を設定
すればよいが、ずらす距離が小さければデッドゾーン解
消の効果が少なく逆に大き過ぎれば出鋼側耐火れんがの
損傷が激しくなる傾向が認められ、50〜250mmが望まし
い範囲と言える。 (実施例) 第1図は、本発明実施例の20tonAOD炉を示し、縦断面
図(a)においてAOD炉1は炉体外径D=2900mmの鉄皮
3の内側に、第2図の場合と同様焼成マグネシアれんが
から成る永久張れんが4、さらにその内側にマグクロ質
ダイレクトボンドれんがから成る内張れんが5を張った
構造をなし、炉上部の内張れんが5の厚さt3,t4はいず
れも280mmである。 第1図(b)はAOD炉1の羽口高さA−Aにおける横
断面を示すもので、羽口側内張れんが5(5a)の内張厚
さt1および出鋼側内張れんが5(5b)の内張厚さt2はそ
れぞれ550mmおよび330mmであり、羽口れんが2は精錬ガ
スが炉体中心Cから距離d=150mmだけ出鋼側炉壁に寄
った位置Pを向く様な構造をなす。 このような形状,構造のAOD炉1を低Cオーステナイ
トステンレス鋼SUS 304Lの精錬に適用した結果、C量
を0.015%まで脱炭するのに約60分を要した従来の同容
量AOD炉での精錬時間を、操業条件を変えることなく約5
0分に短縮できることが確認された。 また、スプラッシュ発生量についても従来1チャージ
あたり約800Kgもあったものが約400Kgまで低減できるこ
とが明らかになった。(Means for Solving Problems) The present invention has been made in consideration of the AOD furnace shape in which the refractory brick lining is asymmetrical, and the refining gas blowing direction of the AOD furnace is deeper than the furnace center. By directing it toward the molten steel central part, the dead zone of the refining reaction is eliminated and the efficient refining throughout the furnace proceeds smoothly, and the gas bubbles become finer, reducing the amount of splash generation and shortening the refining time. In the AOD furnace of the present invention, the intersection of the blowing lines of the refining gas blown into the furnace from the plurality of tuyere provided on the furnace side wall is located at a position displaced from the center of the furnace to the far side. It is characterized by being. In the present invention, the blowing direction of the refining gas does not necessarily have to be completely coincident with the center of the molten steel.
The distance from the center of the furnace body may be set in consideration of capacity, operating conditions, etc. However, if the displacement is small, the effect of eliminating the dead zone is small and conversely if it is too large, damage to the refractory brick on the tapped side becomes severe. A tendency is recognized, and it can be said that the preferable range is 50 to 250 mm. (Example) FIG. 1 shows a 20 ton AOD furnace according to an embodiment of the present invention. In the longitudinal sectional view (a), the AOD furnace 1 is inside the iron shell 3 having a furnace outer diameter D = 2900 mm, as compared with the case of FIG. Similarly, a permanent brick 4 made of fired magnesia brick and a lining brick 5 made of magrophilic direct bond brick are placed inside the brick, and the thickness t 3 and t 4 of the lining brick 5 at the upper part of the furnace are Is also 280 mm. FIG. 1 (b) shows a cross section of the AOD furnace 1 at the tuyere height AA, showing the lining thickness t 1 of the tuyere side lining brick 5 (5a) and the tapping side lining brick. The lining thickness t 2 of 5 (5b) is 550 mm and 330 mm, respectively, and the tuyere brick 2 faces the position P where the refining gas is closer to the tapped side furnace wall by the distance d = 150 mm from the furnace center C. Has a simple structure. As a result of applying the AOD furnace 1 having such a shape and structure to the refining of the low C austenitic stainless steel SUS 304L, it was found that it took about 60 minutes to decarburize the C content to 0.015% in the conventional AOD furnace of the same capacity. About 5 refining times without changing operating conditions
It was confirmed that it could be reduced to 0 minutes. In addition, it was revealed that the amount of splash generated could be reduced to about 400 kg from the conventional amount of about 800 kg per charge.
【発明の効果】 以上詳述したように、本発明はAOD炉の精錬ガス吹込
み方向を溶鋼中心部に向けることによって、精錬時のデ
ッドゾーン発生の防止とスプラッシュ発生量の低減を可
能としたもので、特に低Cステンレス鋼等の精錬におけ
る製鋼歩留および効率の向上に大きく貢献するものであ
る。As described above in detail, the present invention makes it possible to prevent the generation of dead zones and reduce the amount of splash generation during refining by directing the refining gas blowing direction of the AOD furnace toward the molten steel center. In particular, it greatly contributes to the improvement of steelmaking yield and efficiency in refining low C stainless steel and the like.
第1図(a)(b)は本発明実施例におけるAOD炉の構
造を示す各々縦断面図および羽口高さにおける横断面
図、第2図は従来のAOD炉の構造を示す羽口高さにおけ
る横断面図である。 1……AOD炉、 2……羽口れんが、 5……内張れんが、 5a……羽口側内張れんが、 5b……出鋼側内張れんが、 C……炉体中心。1 (a) and 1 (b) are longitudinal sectional views and transverse sectional views at the tuyere height, respectively, showing the structure of the AOD furnace in the embodiment of the present invention, and FIG. 2 is the tuyere height showing the structure of the conventional AOD furnace. FIG. 1 …… AOD furnace, 2 …… tuyere brick, 5 …… lining brick, 5a …… tuyere side lining brick, 5b …… steel side lining brick, C …… hearth center.
Claims (2)
まれる精錬用ガスの吹出し方向線の交点が、炉体の中心
から遠方側にずらした位置にあることを特徴とするAOD
炉。1. An intersection of blow-out direction lines of the refining gas blown into the furnace from a plurality of tuyere provided on a side wall of the furnace is located at a position displaced from a center of the furnace body to a far side. AOD
Furnace.
mのところにあることを特徴とする特許請求の範囲第
(1)項に記載のAOD炉。2. The shifted position is 50 to 250 m from the center of the furnace.
The AOD furnace according to claim (1), which is located at m.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62181232A JP2551013B2 (en) | 1987-07-22 | 1987-07-22 | AOD furnace |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62181232A JP2551013B2 (en) | 1987-07-22 | 1987-07-22 | AOD furnace |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6428318A JPS6428318A (en) | 1989-01-30 |
JP2551013B2 true JP2551013B2 (en) | 1996-11-06 |
Family
ID=16097112
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP62181232A Expired - Lifetime JP2551013B2 (en) | 1987-07-22 | 1987-07-22 | AOD furnace |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2551013B2 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH03103245U (en) * | 1990-02-05 | 1991-10-28 |
-
1987
- 1987-07-22 JP JP62181232A patent/JP2551013B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JPS6428318A (en) | 1989-01-30 |
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