JPH11172319A - Method for blowing gaseous hydrocarbon into molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain same degree of effect as by a triple tube tuyere by using a double tube tuyere, with which a large quantity of gaseous hydrocarbon is blown and the stirring of molten metal is executed, by specifying range of the ratio of the gaseous hydrocarbon flow rate in an inner tube and heat insulating gas flow rate in an outer tube of the double tube tuyere. SOLUTION: As one sample of the double tube tuyere for bottom blowing in a converter, the double tube tuyere is constituted of two tubes (stainless steel-made) of the inner tube 1 and the outer tube 2 set to the furnace bottom part of the converter. The gaseous hydrocarbon 3 in this inner tube 1 and the heat insulating gas 2 or the mixed gas of the heat insulating gas and the gaseous hydrocarbon in the outer tube 2, are introduced. It is desirable to independently control the flow rate of each gas for each flowing passage and each kind of the gas. Here, when Q0 represents flow rate (Nm<3> /min) of the gaseous hydrocarbon 3 in the inner tube 1 and Q represents flow rate (Nm<3> /min) of the heat insulating gas 4 in the outer tube 2, the flow rate ratio Q/Q0 is controlled to in the range of 0.05-1.0. In this way, the wearing speed of the tuyere is restrained to low level and the stable operation can be executed.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、溶融金属中への二
重管を使用した炭化水素ガスの吹き込み方法に関する。The present invention relates to a method for blowing hydrocarbon gas into molten metal using a double pipe.

【０００２】[0002]

【従来の技術】転炉で脱炭精錬を効率よく進行させるた
めに、溶鋼の攪拌を強化するのが有効であることは広く
知られている。そのため、現在の転炉は主な酸素供給源
である上吹きランスに加えて、溶鋼の攪拌を目的として
底吹き羽口を設置し、酸素、炭化水素ガス、不活性ガス
を底吹き羽口を通して溶鋼に吹き込んでいる。2. Description of the Related Art It is widely known that it is effective to enhance the stirring of molten steel in order to efficiently advance decarburization refining in a converter. For this reason, current converters are equipped with a bottom blowing tuyere for the purpose of stirring molten steel in addition to the top blowing lance, which is the main oxygen supply source, and pass oxygen, hydrocarbon gas and inert gas through the bottom blowing tuyere. Injecting into molten steel.

【０００３】発明者らは先に３重管構造の羽口を特開平
５−２１４４２０号公報にて提案し、内管と外管に炭化
水素ガスを、中管に酸素を吹き込むことにより、脱炭時
の溶鋼攪拌を増加する手段として高価な不活性ガスに代
えて安価な炭化水素ガスを大量に吹き込むことが可能と
なることを示したが、下記の問題点がある。The inventors have previously proposed a tuyere having a triple pipe structure in Japanese Patent Application Laid-Open No. Hei 5-214420, and degassed by blowing hydrocarbon gas into the inner pipe and the outer pipe and oxygen into the middle pipe. Although it has been shown that a large amount of inexpensive hydrocarbon gas can be blown in place of expensive inert gas as a means of increasing the stirring of molten steel during coal, there are the following problems.

【０００４】（１）１羽口当たり、ガス流量制御系が３
系統必要であり設備費が高くなる。 （２）ガス通過面積が大きく、ガス量をあまり必要とし
ない吹錬の初期および中期でも、羽口地金湯差し防止用
（地金入り込み防止用にガス圧をかける）の必要ガス量
が単管、二重管羽口の場合よりも多く、ガスコストの上
昇を招く。(1) There are three gas flow control systems per tuyere
The system is required and the equipment cost increases. (2) Even in the initial and middle stages of blowing, which have a large gas passage area and do not require a large amount of gas, the amount of gas required for preventing tuyere smelting (applying gas pressure to prevent metal from entering) is simple. This is more than in the case of tube and double tube tuyere, resulting in an increase in gas cost.

【０００５】[0005]

【発明が解決しようとする課題】本発明の目的は、二重
管羽口を用いて炭化水素ガスを大量に吹き込み、溶融金
属の攪拌を行い、三重管羽口と同等以上の効果を得る方
法を提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to provide a method in which a large amount of hydrocarbon gas is blown in using a double tube tuyere to stir molten metal to obtain an effect equal to or higher than that of a triple tube tuyere. Is to provide.

【０００６】[0006]

【課題を解決するための手段】吹錬前期に、三重管の全
管Ar吹きを行い、吹錬後期に炭化水素ガスとしてLPGを
使用し、内管LPG-中管O₂- 外管LPG に切り替えた後の温
度推移を調査した。The blowing year SUMMARY OF THE INVENTION performs blowing all tubes Ar triple tube, using LPG as the hydrocarbon gas blowing late, the inner tube LPG- middle tube O ₂ - the outer tube LPG The temperature transition after switching was investigated.

【０００７】温度推移は、三重管の溶銑と接する面から
手前50mmの内管内側部に熱電対を埋め込み、温度測定を
行う方法で求めた。[0007] The temperature transition was determined by a method in which a thermocouple was embedded in the inner portion of the inner tube 50 mm in front of the surface in contact with the hot metal of the triple tube, and the temperature was measured.

【０００８】温度推移の調査結果から下記（Ａ）の知
見、（Ｂ）の着想を得た。（Ａ）内管のLPG は、中管の
O₂および外管のLPG によって二重に断熱されており、内
管のLPG が分解温度までに至っていない。The following findings (A) and ideas (B) were obtained from the results of the investigation of temperature changes. (A) The LPG of the inner tube is
Double insulation by O ₂ and LPG in outer tube, LPG in inner tube has not reached decomposition temperature.

【０００９】（Ｂ）三重管のように二重の断熱作用がな
くても、一重（単層）の断熱で内管の炭化水素ガスが分
解温度以下に保持できれば、二重管を使用しても、同様
な炭化水素ガス吹きが可能である。(B) Even if there is no double heat-insulating action as in a triple pipe, if the hydrocarbon gas in the inner pipe can be kept below the decomposition temperature by single (single-layer) heat insulation, a double pipe is used. Also, similar hydrocarbon gas blowing is possible.

【００１０】（Ｂ）の着想を実現する手段として、内管
の炭化水素ガスが羽口内で分解しない臨界的な条件を下
記のように見出し、本発明が完成した。As means for realizing the idea of (B), a critical condition under which the hydrocarbon gas in the inner tube is not decomposed in the tuyere was found as follows, and the present invention was completed.

【００１１】すなわち、本発明は、溶融金属中へ炭化水
素ガスを内管、外管からなる２重管羽口を用いて吹き込
む方法において、内管の炭化水素ガス流量Qoと外管の断
熱性ガス流量Q の比Q/Qoが0.05〜1.0 の範囲であること
を特徴とする炭化水素ガスの吹き込み方法である。That is, the present invention relates to a method of blowing a hydrocarbon gas into a molten metal using a double tube tuyere comprising an inner tube and an outer tube. A hydrocarbon gas blowing method characterized in that the ratio Q / Qo of the gas flow rate Q is in the range of 0.05 to 1.0.

【００１２】[0012]

【発明の実施の形態】本発明の好適態様としては、上・
底吹き精錬に際しての炉底羽口からの炭化水素ガスの吹
き込みが例示される。BEST MODE FOR CARRYING OUT THE INVENTION
Injection of hydrocarbon gas from a furnace bottom tuyere at the time of bottom blowing refining is exemplified.

【００１３】図１は、転炉底吹き用の二重管羽口の一例
であって、転炉の炉底部に設置した内管１、外管２の２
つのパイプ（ステンレス製）から構成されている。FIG. 1 shows an example of a double-tube tuyere for blowing the bottom of a converter. The inner tube 1 and the outer tube 2 are installed at the bottom of the converter.
It consists of two pipes (made of stainless steel).

【００１４】本発明では、この内管に炭化水素ガス３、
外管に断熱性ガス４あるいは断熱性ガスと炭化水素ガス
の混合ガスを導入する。各ガスは流路別、ガス種別に独
立に流量コントロールすることが望ましい。According to the present invention, hydrocarbon gas 3
An insulating gas 4 or a mixed gas of an insulating gas and a hydrocarbon gas is introduced into the outer tube. It is desirable to control the flow rate of each gas independently for each channel and gas type.

【００１５】炭化水素ガスは、CH₄ 、C₂H₆、C₃H₈、C₄H
₁₀ などを単独あるいは混合ガスとして用いる。断熱性
ガスは、Ar、N₂などの不活性ガスが含まれるが、本発明
の狙いとする断熱効果が期待できるCO、CO₂ なども単独
あるいは混合ガスとしてそれぞれ用いることができる。The hydrocarbon gas is CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H
₁₀ or the like is used alone or as a mixed gas. The heat insulating gas includes an inert gas such as Ar or N ₂ , but CO, CO _2, etc., which are expected to achieve the heat insulating effect targeted by the present invention, can be used alone or as a mixed gas.

【００１６】内管（LPG=3 〜12Nm³/min ）外管（Ar=0.1
〜15Nm³/min)の流量（以下、流量は全て羽口１本当たり
の流量を示す）をそれぞれ変えた試験結果を図２に示
す。Inner tube (LPG = 3 to 12 Nm ³ / min) Outer tube (Ar = 0.1
FIG. 2 shows test results obtained by changing the flow rate (to 15 Nm ³ / min) (hereinafter, all flow rates indicate the flow rate per tuyere).

【００１７】図２に示すように、内管の炭化水素ガス
（LPG ）流量をQo(Nm³/min) 、外管の断熱性ガス（Ar）
流量をQ(Nm³/min)とし、流量比Q/Qoで整理するとQ/Qoを
0.05〜1.0 に制御することにより、羽口損耗速度を低く
抑え、安定操業が可能となる。As shown in FIG. 2, the flow rate of hydrocarbon gas (LPG) in the inner pipe is Qo (Nm ³ / min), and the heat insulating gas (Ar) in the outer pipe is
When the flow rate is Q (Nm ³ / min) and the flow rate ratio is Q / Qo, Q / Qo
By controlling to 0.05 to 1.0, the tuyere wear rate can be kept low and stable operation is possible.

【００１８】なお、図２に示す「羽口前圧」は、羽口手
前のガス圧力の値を示し、羽口の閉塞状況を示す指標で
あり、値が低いほど圧損が小さく、ガスの元圧１０kg/c
m²に近づくほど閉塞状況が悪化していることを示す。閉
塞のない通常の「羽口前圧」は、約６kg/cm²である。The "pre-tuyere pressure" shown in FIG. 2 indicates the value of the gas pressure just before the tuyere and is an index indicating the tuyere blockage. The lower the value, the smaller the pressure loss and the lower the gas source. Pressure 10kg / c
closer to m ² indicate that a blockage situation has deteriorated. Usually of "feather preoral pressure" no blockage is about 6kg / cm ^2.

【００１９】流量比Q/Qoが0.05未満になると、外管ガス
による断熱効果が著しく低下し、内管の炭化水素ガス
（LPG ）温度が分解温度以上に上昇し、内管の炭化水素
ガス（LPG ）が分解反応を起こし、この吸熱反応と外管
ガス断熱効果が小さいことが重なり、外管金物温度が低
下し外管金物に接する耐火物温度も低下し、熱スポール
に起因する耐火物剥離が生じて、羽口寿命が著しく悪化
する。When the flow ratio Q / Qo is less than 0.05, the heat insulation effect of the outer pipe gas is significantly reduced, the temperature of the hydrocarbon gas (LPG) in the inner pipe rises above the decomposition temperature, and the hydrocarbon gas ( LPG) causes a decomposition reaction, and this endothermic reaction overlaps with the small outer tube gas insulation effect. Occurs, and the tuyere life is remarkably deteriorated.

【００２０】また、過冷のため溶鉄が凝固して生成する
マッシュルームが過大に成長し、羽口前圧力が増大し安
定操業が不可能となる。Further, mushrooms formed by solidification of molten iron due to undercooling grow excessively, and the pressure in front of the tuyere increases, so that stable operation becomes impossible.

【００２１】流量比Q/Qoが1.0 を超えると、溶銑の飛散
粒子の転炉炉口への付着量が増大し、また飛散粒子が排
気系にまで到達し集塵水中のFe濃度が急激に増大する。
転炉の炉口への地金付着量が増大すると、溶銑の転炉へ
の注銑が困難となり、炉口地金を専用ランスにより溶解
したり、スクレイパーにより地金をはぎ取るといった操
作が頻繁に必要となり、転炉の生産性が低下する問題を
生じる。また、飛散粒子が排気系に到達する量が増大す
ると溶銑歩留まりが低下し生産コストが増大する問題も
生じる。When the flow ratio Q / Qo exceeds 1.0, the amount of the scattered particles of the hot metal adhering to the converter furnace increases, and the scattered particles reach the exhaust system, and the Fe concentration in the dust collection water rapidly increases. Increase.
When the amount of metal ingot on the furnace mouth of the converter increases, it becomes difficult to pour hot metal into the converter, and operations such as melting the furnace mouth metal with a special lance and stripping the metal with a scraper are frequently performed. This necessitates a problem that the productivity of the converter is reduced. Further, when the amount of the scattered particles reaching the exhaust system increases, there arises a problem that the yield of hot metal decreases and the production cost increases.

【００２２】流量比Q/Qoは、好ましくは０．１〜０．５
である。また、この間は、効果の差がほとんど無いた
め、断熱ガスの吹き込み量を減らしても特に支障が無
い。従って、ガスコスト低減の観点からは、流量比がQ/
Qo０．１に近い所が経済的である。The flow ratio Q / Qo is preferably 0.1 to 0.5
It is. Also, during this time, there is almost no difference in effect, so that there is no particular problem even if the blowing amount of the insulating gas is reduced. Therefore, from the viewpoint of gas cost reduction, the flow ratio is Q /
A place near Qo0.1 is economical.

【００２３】なお、図２に示す「鉄歩留まり」は平均的
な三重管での出鋼歩留まりを基準として、増減％を比較
した。The "iron yield" shown in FIG. 2 was compared with the increase / decrease% based on the average tapping yield in a triple pipe.

【００２４】炭化水素ガスのガス種としてCH₄ 、C₂H₆、
C₃H₈、C₄H₁₀ の単体あるいは混合ガスを用い、断熱性ガ
ス種としてAr、N₂、CO、CO₂ の単体あるいは混合ガスを
用いるが上記のQ/Qoの上限値・下限値に影響はない。CH ₄ , C ₂ H ₆ ,
A single or mixed gas of C ₃ H ₈ and C ₄ H ₁₀ is used, and a single or mixed gas of Ar, N ₂ , CO, and CO ₂ is used as the adiabatic gas type, but the upper and lower limits of the above Q / Qo are used. Has no effect.

【００２５】[0025]

【実施例】（実施例１）溶銑250トン(温度1200〜1300℃、
成分は表１に示す）を転炉に装入し、酸素ガスを850Nm³
/minで上吹きランス（6 孔、傾斜角15度、スロート径48
mm、ランス高さ2.5m）から溶鉄に上吹き吹錬した。[Example 1] (Example 1) 250 tons of hot metal (temperature 1200-1300 ° C,
Components charged are shown in Table 1) to the converter, 850 nm ³ oxygen gas
/ min top blow lance (6 holes, inclination angle 15 degrees, throat diameter 48
mm, lance height 2.5m).

【００２６】[0026]

【表１】 [Table 1]

【００２７】転炉の炉底に設けた４本の二重管羽口から
吹錬前期および中期には、内管と外管にCO₂ を流し、吹
錬後期([C]=0.5% 以下) には、内管にLPG を外管にCO₂
を流して、[C]=0.05% になるまで吹錬した。その結果を
表２にまとめて示す。In the first and middle stages of blowing, CO ₂ is passed through the inner tube and the outer tube from four double tube tuyeres provided at the bottom of the converter, and the latter stage of blowing ([C] = 0.5% or less) ), LPG in the inner tube and CO _{2 in the} outer tube
And blown until [C] = 0.05%. Table 2 summarizes the results.

【００２８】比較例１に示す三重管を組み込んだ試験を
行い本発明と比較し、同じく表２に示す。A test incorporating the triple tube shown in Comparative Example 1 was conducted and compared with the present invention.

【００２９】また、三重管羽口とのランニングコスト、
設備費の比較を実施したが、単管での値を基準（１．
０）にした指数で表示した。Also, the running cost with a triple tube tuyere,
A comparison of equipment costs was made, but the value for a single pipe was used as a reference (1.
0).

【００３０】[0030]

【表２】 [Table 2]

【００３１】本発明例１（Q/Qo=0.06 ）〜本発明例４
（Q/Qo=0.9）では、羽口損耗速度が三重管（比較例１の
羽口損耗速度は、0.3mm/ch）並みの0.17〜0.20mm/ch が
得られた。Invention Example 1 (Q / Qo = 0.06) to Invention Example 4
(Q / Qo = 0.9), the tuyere wear rate was 0.17 to 0.20 mm / ch, which was comparable to that of a triple pipe (the tuyere wear rate of Comparative Example 1 was 0.3 mm / ch).

【００３２】また、本発明例５〜本発明例７に示すよう
に、Q/Qo=0.2が一定の条件下、断熱性ガスの種類を変え
ても羽口損耗速度は、0.17mm/ch と一定であった。Further, as shown in Inventive Examples 5 to 7, under the condition that Q / Qo = 0.2 is constant, the tuyere wear rate is 0.17 mm / ch even when the type of the insulating gas is changed. It was constant.

【００３３】比較例２（Q/Qo=0.04 ）、比較例３（Q/Qo
=1.2）では、羽口損耗速度はそれぞれ1.0 、1.1 mm/ch
と早くなった。 二重管羽口のガスコストは、三重管の
約半分、設備費は約１／３と小さかった。Comparative Example 2 (Q / Qo = 0.04) and Comparative Example 3 (Q / Qo
= 1.2), the tuyere wear rates are 1.0 and 1.1 mm / ch, respectively.
And sooner. The gas cost of the double tube tuyere was about half that of the triple tube, and the equipment cost was as small as about 1/3.

【００３４】[0034]

【発明の効果】本発明により、従来の三重管に比べてラ
ンニングコスト、設備費用を低下でき、しかも三重管並
に炭化水素ガスを吹き込むことができる。According to the present invention, running cost and equipment cost can be reduced as compared with the conventional triple pipe, and hydrocarbon gas can be blown in at the same level as the triple pipe.

【図面の簡単な説明】[Brief description of the drawings]

【図１】二重管の羽口の構造と使用方法を示す概念図で
ある。FIG. 1 is a conceptual diagram showing the structure of a tuyere of a double pipe and a method of using the tuyere.

【図２】Q/Q₀と鉄歩留まり指数、羽口前圧力との関係を
示すグラフである。FIG. 2 is a graph showing a relationship between Q / Q ₀ , an iron yield index, and a tuyere pre-pressure.

【符号の説明】[Explanation of symbols]

１：内管、 ２：外管、 ３：炭化水素ガス、 ４：断熱性ガス 1: inner pipe, 2: outer pipe, 3: hydrocarbon gas, 4: heat insulating gas

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 溶融金属中へ炭化水素ガスを内管、外管
からなる２重管羽口を用いて吹き込む方法において、内
管の炭化水素ガス流量Qoと外管の断熱性ガス流量Q の比
Q/Qoが0.05〜1.0 の範囲であることを特徴とする炭化水
素ガスの吹き込み方法。1. A method of blowing a hydrocarbon gas into a molten metal by using a double-tube tuyere comprising an inner tube and an outer tube, wherein a hydrocarbon gas flow rate Qo of the inner pipe and a heat-insulating gas flow rate Q 2 of the outer pipe are determined. ratio
A method for blowing hydrocarbon gas, wherein Q / Qo is in the range of 0.05 to 1.0.