JP5463623B2 - Brick structure of converter bottom blowing tuyere - Google Patents

Brick structure of converter bottom blowing tuyere Download PDF

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JP5463623B2
JP5463623B2 JP2008080815A JP2008080815A JP5463623B2 JP 5463623 B2 JP5463623 B2 JP 5463623B2 JP 2008080815 A JP2008080815 A JP 2008080815A JP 2008080815 A JP2008080815 A JP 2008080815A JP 5463623 B2 JP5463623 B2 JP 5463623B2
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JP2009235457A (en
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誠 加藤
久樹 加藤
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JFE Steel Corp
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Description

本発明は、精錬用ガスのガス吹込管を有し、マグネシア・カーボン煉瓦からなる羽口煉瓦と、該羽口煉瓦を囲む、マグネシア・カーボン煉瓦からなる羽口周囲煉瓦とから構成され、転炉の底部に設置される底吹き羽口の煉瓦構造に関するものである。   The present invention has a gas injection pipe for refining gas, and is composed of a tuyere brick made of magnesia carbon brick and a tuyere surrounding brick made of magnesia carbon brick surrounding the tuyere brick, It is related with the brick structure of the bottom blowing tuyere installed in the bottom part.

溶銑の脱炭精錬や脱燐精錬、更には鉄の溶融還元製錬を実施する転炉には、その底部に、精錬用のガスを吹き込むための底吹き羽口が設置されている。この羽口は、通常、その内部に金属製のガス吹込管を有する羽口煉瓦と、この羽口煉瓦の周囲を囲む羽口周囲煉瓦とで構成されている。ガス吹込管からは、Ａｒガスや窒素ガスなどが攪拌用ガスとして吹き込まれたり、酸素ガスが脱炭反応用ガスとして吹き込まれたりしている。羽口煉瓦及び羽口周囲煉瓦は、耐侵食性や耐摩耗性に優れることから、マグネシア・カーボン煉瓦で構成されることが一般的に行われている。尚、本発明においては、攪拌用ガス及び脱炭反応用ガスなど、精錬或いは製錬で使用するガスを全て精錬用ガスと定義する。   In a converter that performs hot metal decarburization and dephosphorization, and further iron smelting reduction refining, a bottom blowing tuyere for blowing a gas for refining is installed at the bottom. The tuyere is usually composed of tuyere bricks having a metal gas blowing pipe inside and tuyere surrounding bricks surrounding the tuyere bricks. From the gas blowing tube, Ar gas, nitrogen gas or the like is blown as a stirring gas, or oxygen gas is blown as a decarburization reaction gas. The tuyere brick and the tuyere surrounding brick are generally made of magnesia carbon brick because they are excellent in erosion resistance and wear resistance. In the present invention, all gases used in refining or refining, such as stirring gas and decarburization reaction gas, are defined as refining gas.

この構造の底吹き羽口においては、ガス吹込管から、室温つまり低温のガスが吹き込まれるために、羽口煉瓦及び羽口周囲煉瓦はガス吹込管を通過するガスによって冷却される。特に、羽口煉瓦の冷却は著しく、羽口煉瓦自体に温度差が生ずるとともに、羽口周囲煉瓦との間に大きな温度差が生じやすい。この温度差による熱応力に起因して羽口煉瓦に亀裂などが発生し、羽口煉瓦の損傷が進行する。また、ガスのバックアタックも生じるために羽口煉瓦の損傷は助長され、底吹き羽口の耐用性低下をもたらしている。この問題を解決するべく、多数の提案がなされている。   In the bottom blowing tuyere of this structure, room temperature, that is, low-temperature gas is blown from the gas blowing pipe, so that the tuyere brick and the tuyere surrounding brick are cooled by the gas passing through the gas blowing pipe. In particular, the cooling of the tuyere bricks is remarkable, and a temperature difference occurs in the tuyere bricks themselves, and a large temperature difference tends to occur between the tuyere bricks. Due to the thermal stress due to this temperature difference, cracks and the like occur in the tuyere brick, and damage to the tuyere brick proceeds. In addition, gas back-attack is also generated, so that damage to the tuyere bricks is promoted, resulting in reduced durability of the bottom-blown tuyere. Many proposals have been made to solve this problem.

例えば、特許文献１には、「ガス吹込管と該ガス吹込管を囲む羽口煉瓦とからなる底吹き羽口において、前記ガス吹込管が、黒鉛パイプと、それに内挿された金属パイプと、前記黒鉛パイプの外面側に設けられた長繊維強化断熱層体からなる３層構造である底吹き羽口」が開示されている。特許文献１によれば、ガス吹込管の異常溶損がなくなり、羽口煉瓦の冷却も抑制され、羽口の損耗速度を低減でき、精錬炉の炉体寿命の延長に寄与できる旨が記載されている。   For example, in Patent Document 1, “in a bottom blowing tuyere composed of a gas blowing pipe and a tuyere brick surrounding the gas blowing pipe, the gas blowing pipe includes a graphite pipe and a metal pipe inserted therein. A bottom blow tuyere having a three-layer structure composed of a long fiber reinforced heat insulating layer provided on the outer surface side of the graphite pipe is disclosed. According to Patent Document 1, it is described that abnormal melting loss of the gas blowing pipe is eliminated, cooling of the tuyere bricks is suppressed, the wear rate of the tuyere can be reduced, and the lifetime of the refining furnace can be extended. ing.

また、特許文献２には、「カーボン含有の羽口煉瓦とカーボン含有の羽口周囲煉瓦とからなる底吹き羽口において、前記羽口煉瓦及び羽口周囲煉瓦のカーボン含有量を、それぞれＣｔ及びＣｂと表したとき、１００質量％＞Ｃｔ＞０質量％及び１００質量％＞Ｃｂ＞０質量％であり、且つ、［ΔＬ＝−225.921＋15.951Ｃｔ＋0.905Ｃｂ−0.304Ｃｔ2＋0.189Ｃｂ2］の式で求められるΔＬが６０以下になるＣｔ及びＣｂの組み合わせとする煉瓦構造」が開示されている。具体的には、例えば、羽口周囲煉瓦のカーボン量（Ｃｂ）を２０質量％に設定した場合、羽口煉瓦のカーボン量（Ｃｔ）は、約１８．７質量％以下または約３４質量％以上が妥当であるとしている。特許文献２によれば、上記のカーボン含有量とすることで、羽口煉瓦と羽口周囲煉瓦との間の隙間を小さく設定することができ、その結果、前記隙間への地金差しによるスポーリング損傷が生じなくなり、羽口煉瓦の耐用を大幅に向上できる旨が記載されている。
特開平１０−２８００２７号公報 特開２００３−２６１３７４号公報 Patent Document 2 states that, in a bottom-blown tuyere composed of a carbon-containing tuyere brick and a carbon-containing tuyere surrounding brick, the carbon content of the tuyere brick and the tuyere surrounding brick is set to Ct and When expressed as Cb, 100 mass%>Ct> 0 mass% and 100 mass%>Cb> 0 mass%, and [ΔL = −225.921 + 15.951 Ct + 0.905 Cb−0.304 Ct 2 +0.189 Cb 2 ] A “brick structure that is a combination of Ct and Cb with which ΔL determined by the equation is 60 or less” is disclosed. Specifically, for example, when the carbon amount (Cb) of the tuyere surrounding brick is set to 20% by mass, the carbon amount (Ct) of the tuyere brick is about 18.7% by mass or less or about 34% by mass or more. Is reasonable. According to Patent Document 2, by setting the above-described carbon content, the gap between the tuyere brick and the tuyere surrounding brick can be set small. It is described that the polling damage does not occur and the durability of the tuyere brick can be greatly improved.
JP-A-10-280027 JP 2003-261374 A

上記のような提案がなされているにも拘わらず、依然として羽口煉瓦の損傷は収まらず、底吹き羽口の耐用性は向上していないのが実情である。   Despite the above proposals, the actual situation is that the tuyere bricks are still not damaged and the durability of the bottom-blown tuyere is not improved.

本発明は上記事情に鑑みてなされたもので、その目的とするところは、精錬用ガスのガス吹込管を有し、マグネシア・カーボン煉瓦からなる羽口煉瓦と、該羽口煉瓦を囲む、マグネシア・カーボン煉瓦からなる羽口周囲煉瓦とから構成される底吹き羽口において、羽口煉瓦の損傷を抑制し、長期間の使用に耐えることのできる、転炉底吹き羽口の煉瓦構造を提供することである。   The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tuyere brick made of magnesia-carbon brick having a gas blowing pipe for refining gas, and surrounding the tuyere brick, magnesia・ Provides a brick structure for converter bottom-blown tuyere that suppresses damage to tuyere bricks and can withstand long-term use in bottom-blown tuyers composed of carbon bricks. It is to be.

上記課題を解決するための第１の発明に係る転炉底吹き羽口の煉瓦構造は、精錬用ガスを吹き込むためのガス吹込管を有し、マグネシア・カーボン煉瓦からなる羽口煉瓦と、該羽口煉瓦を囲む、マグネシア・カーボン煉瓦からなる羽口周囲煉瓦と、から構成され、転炉の底部に設置される底吹き羽口の煉瓦構造において、前記羽口煉瓦のカーボン含有量が前記羽口周囲煉瓦のカーボン含有量よりも低く、これにより、羽口煉瓦の熱膨張率が羽口周囲煉瓦の熱膨張率に比較して相対的に大きく、且つ、羽口煉瓦の熱伝導率が羽口周囲煉瓦の熱伝導率に比較して相対的に小さいことを特徴とするものである。   A brick structure of a converter bottom blowing tuyere according to the first invention for solving the above-mentioned problem has a gas blowing pipe for blowing a refining gas, and a tuyere brick made of magnesia carbon brick, A bottom-blown tuyere brick structure that is installed at the bottom of a converter and surrounds the tuyere brick, and has a carbon content of the tuyere brick. Lower than the carbon content of the perimeter of the brick, so that the thermal expansion coefficient of the tuyere brick is relatively large compared to the thermal expansion coefficient of the perimeter of the tuyere and the thermal conductivity of the tuyere brick is lower. It is characterized by being relatively small compared to the thermal conductivity of the brick around the mouth.

第２の発明に係る転炉底吹き羽口の煉瓦構造は、第１の発明において、前記羽口煉瓦のカーボン含有量と前記羽口周囲煉瓦のカーボン含有量との差が５質量％以上であることを特徴とするものである。   In the brick structure of a converter bottom blow tuyere according to the second invention, the difference between the carbon content of the tuyere brick and the carbon content of the bricks around the tuyere is 5% by mass or more. It is characterized by being.

本発明によれば、マグネシア・カーボン煉瓦からなる羽口煉瓦と、該羽口煉瓦を囲む、マグネシア・カーボン煉瓦からなる羽口周囲煉瓦と、から構成される底吹き羽口において、羽口煉瓦の熱膨張率を羽口周囲煉瓦の熱膨張率よりも大きく、且つ、羽口煉瓦の熱伝導率を羽口周囲煉瓦の熱伝導率よりも小さくするので、羽口煉瓦は羽口周囲煉瓦に比較して温度が低いにも拘わらず、羽口煉瓦の熱膨張量は羽口周囲煉瓦の熱膨張量よりも大きくなり、羽口煉瓦と羽口周囲煉瓦との境界で、羽口煉瓦は羽口周囲煉瓦によって拘束され、これにより、羽口煉瓦には圧縮力が働き、羽口煉瓦の温度差によって発生する熱応力が前記圧縮力によって打ち消され、羽口煉瓦における亀裂の発生が抑制されて、底吹き羽口の耐用性が向上する。   According to the present invention, in a bottom-blown tuyere composed of a tuyere brick made of magnesia carbon brick and a tuyere surrounding brick made of magnesia carbon brick surrounding the tuyere brick, The thermal expansion coefficient is larger than the thermal expansion coefficient of the bricks around the tuyere and the thermal conductivity of the tuyere bricks is smaller than the thermal conductivity of the bricks around the tuyere, so the tuyere bricks are compared with the bricks around the tuyere Even though the temperature is low, the thermal expansion of the tuyere bricks is larger than that of the bricks around the tuyere, and the tuyere bricks are located at the boundary between the tuyere bricks and the bricks around the tuyere. Constrained by the surrounding bricks, thereby a compressive force acts on the tuyere bricks, the thermal stress generated by the temperature difference of the tuyere bricks is canceled by the compressive force, and the occurrence of cracks in the tuyere bricks is suppressed, The durability of the bottom blowing tuyere is improved.

以下、本発明を具体的に説明する。   Hereinafter, the present invention will be specifically described.

本発明者等は、ガス吹込管を有し、マグネシア・カーボン煉瓦からなる羽口煉瓦と、該羽口煉瓦を囲む、マグネシア・カーボン煉瓦からなる羽口周囲煉瓦と、から構成される底吹き羽口の耐用性を向上させるべく、実炉における羽口煉瓦の損傷状況を詳細に検討し解析した。その結果、羽口煉瓦の主たる損傷原因は、羽口煉瓦での熱応力などに起因する亀裂の発生であり、この亀裂の発生によって稼働面側から一気に数１０ｍｍを超える範囲で損傷が生じていることが分かった。   The inventors of the present invention have a bottom blowing feather having a gas blowing pipe, and a tuyere brick made of magnesia / carbon brick and a tuyere surrounding brick made of magnesia / carbon brick surrounding the tuyere brick In order to improve the endurance of the mouth, the damage situation of tuyere bricks in an actual furnace was examined and analyzed in detail. As a result, the main cause of damage of tuyere bricks is the occurrence of cracks due to thermal stress in tuyere bricks, and the occurrence of cracks causes damage within a range exceeding several tens of millimeters from the operating surface side at once. I understood that.

そこで、この亀裂の発生原因を調査した。図１に、その底部に底吹き羽口が配置された転炉の一部分の概略図を示し、図２に、図１のＸ−Ｘ’矢視による概略図を示す。尚、図２では、底吹き羽口の周囲のワーク煉瓦は図示せずに省略している。   Therefore, the cause of this crack was investigated. FIG. 1 shows a schematic view of a part of a converter in which a bottom blowing tuyere is arranged at the bottom, and FIG. 2 shows a schematic view taken along line X-X ′ of FIG. 1. In FIG. 2, the work bricks around the bottom blowing tuyere are not shown and are omitted.

図１及び図２に示すように、転炉は、外殻をなす鉄皮６と、鉄皮６の内側の鉄皮６に接触する部分に内張りされた永久煉瓦１０と、永久煉瓦１０の内側に内張りされた、消耗部材としてのワーク煉瓦９とを有している。図ではワーク煉瓦９及び永久煉瓦１０が一層張りであるが、二層張り以上としてもよい。転炉底部には、ワーク煉瓦９及び永久煉瓦１０を貫通し、且つワーク煉瓦９及び永久煉瓦１０に嵌合して、底吹き羽口１が設けられ、この底吹き羽口１を介して転炉内の鉄浴に、Ａｒガス、窒素ガス、炭酸ガスなどの攪拌用ガス、更には、脱炭反応用の酸素ガスが精錬用ガスとして吹き込まれ、鉄浴を撹拌或いは精錬するようになっている。図１では、底吹き羽口１が１基のみ示されているが、転炉の底部には複数の底吹き羽口１が設けられている。   As shown in FIGS. 1 and 2, the converter includes an iron shell 6 that forms an outer shell, a permanent brick 10 that is lined on a portion that contacts the iron shell 6 inside the iron shell 6, and an inner side of the permanent brick 10. And a work brick 9 as a consumable member that is lined inside. In the figure, the work brick 9 and the permanent brick 10 are one-layered, but may be two-layered or more. A bottom blowing tuyere 1 is provided at the bottom of the converter through the work brick 9 and the permanent brick 10 and fitted to the work brick 9 and the permanent brick 10. Stirring gas such as Ar gas, nitrogen gas, carbon dioxide gas, and oxygen gas for decarburization reaction is blown into the iron bath in the furnace as a refining gas, and the iron bath is stirred or refined. Yes. In FIG. 1, only one bottom blowing tuyere 1 is shown, but a plurality of bottom blowing tuyere 1 is provided at the bottom of the converter.

底吹き羽口１は、ガス吹込管２と、ガス吹込管２を囲むように設けられた羽口煉瓦３と、この羽口煉瓦３を囲む羽口周囲煉瓦４と、上述した攪拌用ガスまたは精錬用ガスを供給するためのガス導入管５とを備えている。ガス導入管５を介して導入された攪拌用ガスまたは精錬用ガスは、ガス吹込管２から鉄浴中に吹き込まれる。   The bottom blowing tuyere 1 includes a gas blowing pipe 2, a tuyere brick 3 provided so as to surround the gas blowing pipe 2, a tuyere surrounding brick 4 surrounding the tuyere brick 3, and the above-described stirring gas or And a gas introduction pipe 5 for supplying a gas for refining. The stirring gas or the refining gas introduced through the gas introduction pipe 5 is blown into the iron bath from the gas blowing pipe 2.

鉄皮６にはフランジ７が設けられており、底吹き羽口１はフランジ７の開口部を介して転炉内に挿入され、羽口押え蓋８によって保持されている。羽口煉瓦３及び羽口周囲煉瓦４は、マグネシア・カーボン煉瓦で構成されている。この底吹き羽口１を成型する際には、先ず、ガス吹込管２と羽口煉瓦３とが圧縮成形され、その後、成型された羽口煉瓦３の周囲に羽口周囲煉瓦４が圧縮成型されて、全体が一体的に構成されている。   The iron skin 6 is provided with a flange 7, and the bottom blowing tuyere 1 is inserted into the converter through the opening of the flange 7 and held by the tuyere presser cover 8. The tuyere brick 3 and the tuyere surrounding brick 4 are made of magnesia carbon brick. When the bottom blow tuyere 1 is molded, first, the gas blowing pipe 2 and the tuyere brick 3 are compression molded, and then the tuyere surrounding brick 4 is compression molded around the molded tuyere brick 3. Thus, the whole is integrally formed.

尚、図に示す底吹き羽口１は、１本のガス吹込管２を有しているが、底吹き羽口１はこのような構造のもの（「単管型羽口」という）に限るものではなく、目的に応じて適宜選択すればよい。例えば、ガス吹込管２を多重管の１本のみ（「多重管型羽口」という）としても、また、複数のガス吹込管２を有する構造（「多孔型羽口」という）としても構わない。   The bottom blowing tuyere 1 shown in the figure has one gas blowing pipe 2, but the bottom blowing tuyere 1 is limited to such a structure (referred to as “single tube tuyere”). What is necessary is just to select suitably according to the objective. For example, the gas blowing tube 2 may be a single multiple tube (referred to as “multiple tube tuyere”) or a structure having a plurality of gas blowing tubes 2 (referred to as “porous tuyere”). .

このような構成の底吹き羽口１において、転炉に溶銑や溶鋼が収容された状態でガス吹込管２から常温の精錬用ガスを吹き込むと、ガス吹込管２は精錬用ガスによって冷却され、それに応じてガス吹込管２の周囲の羽口煉瓦３も冷却され、羽口煉瓦３は羽口周囲煉瓦４に比較して低温になる。   In the bottom blowing tuyere 1 having such a configuration, when normal temperature refining gas is blown from the gas blowing pipe 2 in a state where the molten iron or molten steel is accommodated in the converter, the gas blowing pipe 2 is cooled by the refining gas, Accordingly, the tuyere brick 3 around the gas blowing tube 2 is also cooled, and the tuyere brick 3 becomes cooler than the tuyere brick 4.

また、使用中の羽口煉瓦３に対する、煉瓦の長さ（内張りの深さ）方向の熱の授受を考えると、炉内の鉄浴の熱は、稼動面（炉内側の露出面）から供給されるが、精錬処理時間内には熱の授受が定常状態には至らないため、羽口煉瓦３の深さ方向に温度差が発生する。その結果、温度の高い稼動面側での煉瓦の熱膨張量に対して、温度の低い内部では相対的に熱膨張量が小さくなるため、境界部分では大きな熱応力が発生し割れが発生すると考えられる。   Considering the transfer of heat in the length of the brick (lining depth) to the tuyere brick 3 in use, the heat of the iron bath in the furnace is supplied from the working surface (exposed surface inside the furnace). However, since heat transfer does not reach a steady state within the refining treatment time, a temperature difference occurs in the depth direction of the tuyere brick 3. As a result, the amount of thermal expansion is relatively small in the low temperature interior compared to the amount of thermal expansion of the brick on the working surface side where the temperature is high. It is done.

また、マグネシア・カーボン煉瓦における温度と熱膨張率との関係を図３に示す。図３に示すように、温度の上昇に比例して熱膨張率が高くなり、また、カーボン含有量が低くなるほど熱膨張率は高くなる。図３には、マグネシア煉瓦の熱膨張率も併せて示す。   FIG. 3 shows the relationship between the temperature and the coefficient of thermal expansion in magnesia / carbon brick. As shown in FIG. 3, the coefficient of thermal expansion increases in proportion to the increase in temperature, and the coefficient of thermal expansion increases as the carbon content decreases. FIG. 3 also shows the thermal expansion coefficient of magnesia brick.

底吹き羽口１における熱膨張の方向は、底吹き羽口１の長手方向中心位置から外側に向かう方向であり、つまり、底吹き羽口１の周囲のワーク煉瓦９や永久煉瓦１０に向かう方向である。従って、羽口煉瓦３と羽口周囲煉瓦４とが同一の材質である場合や、羽口煉瓦３のカーボン含有量が羽口周囲煉瓦４のカーボン含有量よりも高い場合には、羽口煉瓦３の方が低温であることから、羽口煉瓦３の熱膨張量の方が羽口周囲煉瓦４よりも少なく、羽口周囲煉瓦４による羽口煉瓦３の拘束力が低下する。   The direction of thermal expansion in the bottom blowing tuyere 1 is the direction from the center position in the longitudinal direction of the bottom blowing tuyere 1 toward the outside, that is, the direction toward the work brick 9 and the permanent brick 10 around the bottom blowing tuyere 1. It is. Therefore, when the tuyere brick 3 and the tuyere brick 4 are made of the same material, or when the carbon content of the tuyere brick 3 is higher than the carbon content of the tuyere brick 4, the tuyere brick 3 has a lower temperature, the amount of thermal expansion of the tuyere brick 3 is less than that of the tuyere brick 4, and the binding force of the tuyere brick 3 by the tuyere brick 4 is reduced.

この拘束力が弱くなることにより、羽口煉瓦３の内部の温度が１０００℃以下となる部分で熱応力などに起因して割れが発生し、羽口煉瓦３の損傷が進行するとの結論に至った。つまり、羽口煉瓦３の亀裂の主たる発生原因は、熱膨張量の差に由来する羽口周囲煉瓦４による羽口煉瓦３の拘束力の低下であることが分かった。   As the binding force becomes weaker, it is concluded that cracks occur due to thermal stress or the like in the portion where the temperature inside the tuyere brick 3 is 1000 ° C. or less, and damage to the tuyere brick 3 progresses. It was. That is, it has been found that the main cause of the crack in the tuyere brick 3 is a decrease in the binding force of the tuyere brick 3 due to the tuyere surrounding brick 4 resulting from the difference in thermal expansion.

これらの検討結果から、羽口煉瓦３における亀裂発生を抑制するためには、羽口煉瓦３の熱膨張量を羽口周囲煉瓦４の熱膨張量よりも大きくすることであり、そのためには、少なくとも羽口煉瓦３の熱膨張率を羽口周囲煉瓦４の熱膨張率よりも高くすることが必要であり、また、羽口煉瓦３の温度降下を抑制するために羽口煉瓦３の熱伝導率を低くすることも効果があるとの知見を得た。これらによって、羽口煉瓦３には、羽口周囲煉瓦４よりも大きな熱膨張が発生することになる。   From these examination results, in order to suppress the occurrence of cracks in the tuyere brick 3, it is to make the thermal expansion amount of the tuyere brick 3 larger than the thermal expansion amount of the tuyere surrounding brick 4, and for that purpose, At least the thermal expansion coefficient of the tuyere brick 3 needs to be higher than the thermal expansion coefficient of the tuyere brick 4, and in order to suppress the temperature drop of the tuyere brick 3, the heat conduction of the tuyere brick 3 It was found that lowering the rate is also effective. As a result, the thermal expansion of the tuyere brick 3 is larger than that of the tuyere surrounding brick 4.

羽口煉瓦３の熱膨張率を高くし且つ熱伝導率を低くすることは、羽口煉瓦３を構成するマグネシア・カーボン煉瓦のカーボン含有量を、羽口周囲煉瓦４を構成するマグネシア・カーボン煉瓦のカーボン含有量よりも低くすれば達成される。そこで、羽口煉瓦３をカーボン含有量が１５質量％のマグネシア・カーボン煉瓦、羽口周囲煉瓦４をカーボン含有量が２０質量％のマグネシア・カーボン煉瓦で構成し、実機での試験を実施した。   Increasing the thermal expansion coefficient and lowering the thermal conductivity of the tuyere brick 3 means that the carbon content of the magnesia carbon brick constituting the tuyere brick 3 is the same as the magnesia carbon brick constituting the tuyere brick 4. This is achieved by lowering the carbon content. Therefore, the tuyere brick 3 was composed of magnesia / carbon brick having a carbon content of 15% by mass, and the tuyere surrounding brick 4 was composed of magnesia / carbon brick having a carbon content of 20% by mass, and an actual test was performed.

その結果、羽口煉瓦３をカーボン含有量が１５質量％のマグネシア・カーボン煉瓦とし、羽口周囲煉瓦４をカーボン含有量が２０質量％のマグネシア・カーボン煉瓦とすることで、羽口煉瓦３の損耗速度は、羽口煉瓦３及び羽口周囲煉瓦４をともにカーボン含有量が２０質量％のマグネシア・カーボン煉瓦とした場合に比較して、低減することが確認された。   As a result, the tuyere brick 3 is a magnesia carbon brick having a carbon content of 15% by mass, and the perimeter of the tuyere 4 is a magnesia carbon brick having a carbon content of 20% by mass. It was confirmed that the wear rate was reduced as compared with the case where the tuyere brick 3 and the tuyere surrounding brick 4 were both magnesia carbon bricks having a carbon content of 20% by mass.

本発明は、上記試験結果に基づきなされたもので、精錬用ガスを吹き込むためのガス吹込管２を有し、マグネシア・カーボン煉瓦からなる羽口煉瓦３と、羽口煉瓦３を囲む、マグネシア・カーボン煉瓦からなる羽口周囲煉瓦４と、から構成され、転炉の底部に設置される底吹き羽口１の煉瓦構造において、羽口煉瓦３のカーボン含有量が羽口周囲煉瓦４のカーボン含有量よりも低く、これにより、羽口煉瓦３の熱膨張率が羽口周囲煉瓦４の熱膨張率に比較して相対的に大きく、且つ、羽口煉瓦３の熱伝導率が羽口周囲煉瓦４の熱伝導率に比較して相対的に小さいことを特徴とする。   The present invention was made on the basis of the above test results, and has a gas blowing pipe 2 for blowing a refining gas, a tuyere brick 3 made of magnesia carbon brick, and surrounding the tuyere brick 3, In the brick structure of the bottom-blown tuyere 1 composed of carbon bricks and around the tuyere 4 and installed at the bottom of the converter, the carbon content of the tuyere brick 3 is the carbon content of the bricks around the tuyere 4 The thermal expansion coefficient of the tuyere brick 3 is relatively larger than the thermal expansion coefficient of the tuyere surrounding brick 4, and the thermal conductivity of the tuyere brick 3 is lower than the quantity. 4 is relatively small compared to the thermal conductivity of 4.

本発明を適用する場合に、羽口煉瓦３と羽口周囲煉瓦４とのカーボン含有量の差は５質量％以上あれば十分である。但し、本発明においては、羽口煉瓦３の熱膨張量を羽口周囲煉瓦４の熱膨張量よりも大きくすることが必要であり、羽口煉瓦３と羽口周囲煉瓦４との温度差が小さい場合には、カーボン含有量の差を５質量％よりも小さくしても、羽口煉瓦３の熱膨張量を羽口周囲煉瓦４の熱膨張量よりも大きくすることができるので、温度条件などを鑑みて、カーボン含有量に差を付ければよい。また、逆に羽口煉瓦３と羽口周囲煉瓦４との温度差が大きい場合には、カーボン含有量の差を大きくしなければならないが、カーボン含有量の差は２５質量％あれば十分である。   When the present invention is applied, it is sufficient that the difference in carbon content between the tuyere brick 3 and the tuyere surrounding brick 4 is 5% by mass or more. However, in the present invention, the thermal expansion amount of the tuyere brick 3 needs to be larger than the thermal expansion amount of the tuyere surrounding brick 4, and the temperature difference between the tuyere brick 3 and the tuyere surrounding brick 4 is large. If it is small, the thermal expansion amount of the tuyere brick 3 can be made larger than the thermal expansion amount of the tuyere surrounding brick 4 even if the difference in carbon content is less than 5% by mass. In view of the above, the carbon content may be made different. Conversely, when the temperature difference between the tuyere brick 3 and the tuyere surrounding brick 4 is large, the difference in carbon content must be increased, but a difference in carbon content of 25% by mass is sufficient. is there.

本発明によれば、羽口煉瓦３は羽口周囲煉瓦４に比較して温度が低いにも拘わらず、羽口煉瓦３の熱膨張量は羽口周囲煉瓦４の熱膨張量よりも大きくなり、羽口煉瓦３は羽口周囲煉瓦４によって拘束され、これにより、羽口煉瓦３には圧縮力が働き、羽口煉瓦３の温度差などによって発生する熱応力が前記圧縮力によって打ち消され、羽口煉瓦３における亀裂の発生が抑制されて、底吹き羽口１の耐用性が向上する。   According to the present invention, the thermal expansion amount of the tuyere brick 3 is larger than the thermal expansion amount of the tuyere brick 4 although the temperature of the tuyere brick 3 is lower than that of the tuyere brick 4. The tuyere brick 3 is constrained by the tuyere surrounding brick 4, whereby a compressive force acts on the tuyere brick 3, and the thermal stress generated by the temperature difference of the tuyere brick 3 is canceled by the compressive force, The occurrence of cracks in tuyere brick 3 is suppressed, and the durability of bottom-blown tuyere 1 is improved.

前述した図１に示す底吹き羽口において、羽口煉瓦をカーボン含有量が１５質量％のマグネシア・カーボン煉瓦、羽口周囲煉瓦をカーボン含有量が２０質量％のマグネシア・カーボン煉瓦で構成し、実機試験（試験水準１）を行った。また、比較のために、羽口煉瓦及び羽口周囲煉瓦ともに、カーボン含有量が２０質量％のマグネシア・カーボン煉瓦で構成した実機試験（試験水準２）も行った。表１に、使用したマグネシア・カーボン煉瓦の品質特性を示す。   In the bottom-blown tuyere shown in FIG. 1, the tuyere brick is composed of magnesia carbon brick with a carbon content of 15% by mass, and the brick around the tuyere is composed of magnesia carbon brick with a carbon content of 20% by mass, An actual machine test (test level 1) was conducted. For comparison, an actual machine test (test level 2) in which both the tuyere brick and the tuyere brick were made of magnesia carbon brick having a carbon content of 20% by mass was also conducted. Table 1 shows the quality characteristics of the magnesia carbon bricks used.

Figure 0005463623
Figure 0005463623

羽口煉瓦の損耗抑制の評価は、定期的にレーザプロファイル計で測定を行い、測定間の数値変化から求めた損耗速度によって行った。試験水準１及び試験水準２における損耗速度を比較すると、図４に示すように、試験水準１では試験水準２に比較して約８％の損耗速度の改善が得られた。   Evaluation of wear suppression of tuyere bricks was carried out by periodically measuring with a laser profile meter and using the wear rate determined from the numerical change between measurements. Comparing the wear rate at the test level 1 and the test level 2, as shown in FIG. 4, the test level 1 improved the wear rate by about 8% compared to the test level 2.

このように、本発明を適用することにより、底吹き羽口の耐用性が向上することが確認できた。   Thus, it was confirmed that the durability of the bottom blowing tuyere was improved by applying the present invention.

底部に底吹き羽口が配置された転炉の一部分を示す概略図である。It is the schematic which shows a part of converter with the bottom blowing tuyere arrange | positioned at the bottom part. 図１のＸ−Ｘ’矢視による概略図である。It is the schematic by the X-X 'arrow of FIG. マグネシア・カーボン煉瓦での温度と熱膨張率との関係を示す図である。It is a figure which shows the relationship between the temperature in a magnesia carbon brick, and a thermal expansion coefficient. 試験水準１及び試験水準２における損耗速度を比較して示す図である。It is a figure which compares and shows the wear rate in the test level 1 and the test level 2. FIG.

符号の説明Explanation of symbols

１ 底吹き羽口
２ ガス吹込管
３ 羽口煉瓦
４ 羽口周囲煉瓦
５ ガス導入管
６ 鉄皮
７ フランジ
８ 羽口押え蓋
９ ワーク煉瓦
１０ 永久煉瓦 DESCRIPTION OF SYMBOLS 1 Bottom blowing tuyere 2 Gas blowing pipe 3 Tubular brick 4 Brick around bricks 5 Gas introduction pipe 6 Iron skin 7 Flange 8 Tuyere presser cover 9 Work brick 10 Permanent brick

Claims (1)

精錬用ガスを吹き込むためのガス吹込管を内部に有する、マグネシア・カーボン煉瓦からなる羽口煉瓦と、該羽口煉瓦を直接囲む部材である、マグネシア・カーボン煉瓦からなる羽口周囲煉瓦と、から構成される底吹き羽口であって、前記ガス吹込管と前記羽口煉瓦とが圧縮成形され、その後、成形された前記羽口煉瓦の周囲に前記羽口周囲煉瓦が圧縮成形されて、前記羽口煉瓦と前記羽口周囲煉瓦とが一体的に構成された、転炉の底部に設置される底吹き羽口の煉瓦構造において、前記羽口煉瓦のカーボン含有量が前記羽口周囲煉瓦のカーボン含有量よりも５質量％以上低く、これにより、羽口煉瓦の熱膨張率が羽口周囲煉瓦の熱膨張率に比較して相対的に大きく、且つ、羽口煉瓦の熱伝導率が羽口周囲煉瓦の熱伝導率に比較して相対的に小さいことを特徴とする、転炉底吹き羽口の煉瓦構造。 To have the gas blowing tube for blowing the refining gas into the tuyere bricks made of magnesia-carbon bricks, a member surrounding the該羽port bricks directly, and tuyere surrounding bricks made of magnesia-carbon bricks, a bottom-blown tuyeres that consists from the can and the tuyere brick and the gas blowing tube compression molded, then the tuyere surrounding bricks is compression molded around the tuyere bricks molded, In the brick structure of a bottom blow tuyere installed at the bottom of a converter in which the tuyere brick and the brick around the tuyere are integrally formed, the carbon content of the tuyere brick is the brick around the tuyere 5 wt% or more lower than the carbon content, by this, relatively large compared coefficient of thermal expansion of the tuyere bricks to the coefficient of thermal expansion of the tuyere surrounding bricks and, thermal conductivity of the tuyere brick Relative to the thermal conductivity of bricks around tuyere Characterized in that again, brick structure of the converter bottom tuyeres.
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