JP2018003063A - Operation method of electric furnace - Google Patents

Operation method of electric furnace Download PDF

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JP2018003063A
JP2018003063A JP2016128302A JP2016128302A JP2018003063A JP 2018003063 A JP2018003063 A JP 2018003063A JP 2016128302 A JP2016128302 A JP 2016128302A JP 2016128302 A JP2016128302 A JP 2016128302A JP 2018003063 A JP2018003063 A JP 2018003063A
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refractory
furnace
furnace wall
temperature
electric furnace
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JP6673055B2 (en
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尚樹 金子
Naoki Kaneko
尚樹 金子
中川　淳一
Junichi Nakagawa
淳一 中川
勝彦 加藤
Katsuhiko Kato
勝彦 加藤
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Nippon Steel Corp
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Nippon Steel and Sumitomo Metal 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Abstract

PROBLEM TO BE SOLVED: To provide an operation method of an electric furnace capable of achieving both of wear suppression of a refractory and productivity enhancement.SOLUTION: There is provided an operation method of an electric furnace having a refractory furnace wall formed by constructing a refractory on an inner surface of a furnace body, a metal charged into the electrical furnace is dissolved with setting maximum arrival temperature of a surface temperature of the refractory furnace wall on 1 charge at 1000°C to 1800°C, and thermal flux from a surface of the refractory furnace wall to inside of the furnace body at 150 Mcal/m/hour or less in a range of 1000°C to 1800°C of a surface temperature of the refractory furnace wall.SELECTED DRAWING: Figure 1

Description

本発明は、金属原料を溶解する電気炉の操業方法に関する。   The present invention relates to a method for operating an electric furnace for melting a metal raw material.

スクラップあるいは合金等の金属原料の溶解には、例えば、金属原料と電極との間で生じるアークを利用して金属原料を溶解するアーク式電気炉が用いられる。アークは数千℃の高温である。このため、電極近傍の耐火物はアークの輻射熱により損耗する可能性が高い。具体的には、初期の金属原料の溶解では、金属原料によって炉内壁面が被覆されていることから、電力が高位となっても耐火物は損傷しない。しかし、金属原料が溶解した後は、耐火物炉壁はアークに曝されてしまい、直接熱の影響を受けてしまう。このため、電力を高位にすると炉壁の損傷が発生する。一方、耐火物の損耗を抑制しようと電力を過度に低減すると、生産性が落ちる。   For melting a metal raw material such as scrap or alloy, for example, an arc electric furnace that melts a metal raw material using an arc generated between the metal raw material and an electrode is used. The arc is a high temperature of several thousand degrees Celsius. For this reason, the refractory in the vicinity of the electrode is highly likely to be worn out by the radiant heat of the arc. Specifically, in the initial melting of the metal raw material, the inner wall surface of the furnace is covered with the metal raw material, so that the refractory is not damaged even if the power becomes high. However, after the metal raw material is melted, the refractory furnace wall is exposed to the arc and directly affected by heat. For this reason, damage to the furnace wall occurs when the power is increased. On the other hand, if the power is excessively reduced in order to suppress the wear of the refractory, the productivity is lowered.

例えば、耐火物炉壁の表面温度を測定し、耐火物炉壁がアークから受ける輻射熱による損耗の程度を把握することも考えられるが、耐火物炉壁の表面は高温のため、直接測定することが難しい。このため、耐火物炉壁の損耗抑制と生産性とが両立するように電気炉を操業できることが望まれている。   For example, it is conceivable to measure the surface temperature of the refractory furnace wall and grasp the degree of wear due to the radiant heat that the refractory furnace wall receives from the arc, but the surface of the refractory furnace wall should be measured directly because of its high temperature. Is difficult. For this reason, it is desired that the electric furnace can be operated so that the wear suppression of the refractory furnace wall and the productivity are compatible.

例えば、特許文献１には、電気炉の操業において、炉内耐火物の温度を熱伝対で測定し管理する技術が開示されている。特許文献１では、製造品種により溶解時に到達する最高温度が異なることを利用し、例えば到達温度の高い品種の後に到達温度が低い品種を製造するというように製造品種を切り替えることで、耐火物への熱負荷を下げて耐火物溶損を抑制している。また、特許文献２には、電力及び電極と炉壁との距離から導出される耐火物損耗係数に基づいて、生産性の向上と耐火物損耗防止とを考慮した溶融金属の製造方法が開示されている。   For example, Patent Document 1 discloses a technique for measuring and managing the temperature of a refractory in a furnace using a thermocouple in the operation of an electric furnace. In Patent Document 1, by utilizing the fact that the maximum temperature reached at the time of dissolution differs depending on the product type, for example, by switching the product type such that a product type having a low ultimate temperature is manufactured after a product type having a high ultimate temperature, the refractory can be changed. The heat load of the refractory is reduced by reducing the heat load. Patent Document 2 discloses a method for producing a molten metal in consideration of improvement in productivity and prevention of refractory wear based on the refractory wear coefficient derived from electric power and the distance between the electrode and the furnace wall. ing.

特開平５−１０６９６８号公報JP-A-5-106968 特開２００３−１０５４１５号公報JP 2003-105415 A

しかし、上記特許文献１に記載の技術では、製造品種が１種である場合に適用できない。また、炉壁耐火物の温度を測定するときの耐火物の残存厚さは異なり、また、昇熱速度で炉壁表面の状態も異なるため、壁耐火物の温度を測定するのみでは炉壁表面の損耗状態を感知するのは困難である。したがって、耐火物の損耗状態を正確に把握することができず、耐火物の損耗抑制と生産性向上とを両立させるように電気炉を操業することは困難である。   However, the technique described in Patent Document 1 cannot be applied when the number of manufactured varieties is one. Also, the residual thickness of the refractory when measuring the temperature of the furnace wall refractory is different, and the state of the furnace wall surface is also different at the rate of heating, so just measuring the temperature of the wall refractory only It is difficult to detect the state of wear. Therefore, it is difficult to accurately grasp the wear state of the refractory, and it is difficult to operate the electric furnace so as to achieve both the suppression of the wear of the refractory and the improvement in productivity.

また、上記特許文献２に記載の技術では、耐火物損耗係数は電気炉への投入電気に関する関数より導出される。このため、金属溶解前の炉内部保護の有無、水冷パネルによる影響といった炉内部の状況は考慮しておらず、過度に電力を抑制する可能性がある。したがって、耐火物の損耗抑制と生産性向上とを両立させるように電気炉を操業することは困難である。   Further, in the technique described in Patent Document 2, the refractory wear coefficient is derived from a function relating to electricity supplied to the electric furnace. For this reason, the situation inside the furnace such as the presence / absence of protection inside the furnace before melting of the metal and the influence of the water-cooled panel is not taken into consideration, and there is a possibility that the power is excessively suppressed. Therefore, it is difficult to operate the electric furnace so as to achieve both refractory wear suppression and productivity improvement.

そこで、本発明は、上記問題に鑑みてなされたものであり、本発明の目的とするところは、耐火物の損耗抑制と生産性向上とを両立させることが可能な、新規かつ改良された電気炉の操業方法を提供することにある。   Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved electric power capable of achieving both suppression of wear of refractory and improvement of productivity. It is to provide a method of operating the furnace.

上記課題を解決するために、本発明のある観点によれば、炉本体の内面に耐火物を施工して形成された耐火物炉壁を有する電気炉の操業方法であって、１チャージにおける耐火物炉壁の表面温度の最高到達温度を１０００℃以上１８００℃以下とし、かつ、耐火物炉壁の表面温度が１０００℃以上１８００℃以下の範囲では、耐火物炉壁表面から炉本体内部への熱流束が１５０Ｍｃａｌ／ｍ２／ｈｏｕｒ以下となるようにして、電気炉に装入された金属を溶解する、電気炉の操業方法が提供される。 In order to solve the above problems, according to one aspect of the present invention, there is provided a method for operating an electric furnace having a refractory furnace wall formed by constructing a refractory on the inner surface of a furnace body, wherein the refractory in one charge is provided. When the maximum temperature of the surface temperature of the furnace wall is 1000 ° C. or higher and 1800 ° C. or lower and the surface temperature of the refractory furnace wall is 1000 ° C. or higher and 1800 ° C. or lower, the surface from the refractory furnace wall surface to the inside of the furnace body Provided is an electric furnace operating method for melting a metal charged in an electric furnace so that a heat flux is 150 Mcal / m 2 / hour or less.

以上説明したように本発明によれば、耐火物の損耗抑制と生産性向上とを両立させることができる。   As described above, according to the present invention, it is possible to achieve both suppression of refractory wear and improvement in productivity.

本発明の一実施形態に係る電気炉の構成を示す概略平面図である。It is a schematic plan view which shows the structure of the electric furnace which concerns on one Embodiment of this invention. 同実施形態に係る電気炉の炉内温度を測定する熱電対の設置状態を示す部分概略斜視図である。It is a partial schematic perspective view which shows the installation state of the thermocouple which measures the furnace temperature of the electric furnace which concerns on the same embodiment.

以下に添付図面を参照しながら、本発明の好適な実施の形態について詳細に説明する。なお、本明細書及び図面において、実質的に同一の機能構成を有する構成要素については、同一の符号を付することにより重複説明を省略する。   Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol.

＜１．電気炉の構成＞
まず、図１及び図２を参照して、本発明の一実施形態に係る電気炉の概略構成について説明する。図１は、本実施形態に係る電気炉の構成を示す概略平面図である。図２は、本実施形態に係る電気炉の炉内温度を測定する熱電対の設置状態を示す部分概略斜視図である。 <1. Structure of electric furnace>
First, with reference to FIG.1 and FIG.2, schematic structure of the electric furnace which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a schematic plan view showing the configuration of the electric furnace according to the present embodiment. FIG. 2 is a partial schematic perspective view showing an installation state of a thermocouple for measuring the in-furnace temperature of the electric furnace according to the present embodiment.

本実施形態に係る電気炉はアーク式電気炉であって、金属原料と電極との間で生じるアークを利用して金属原料を溶解する。電気炉の炉体は、一般に、溶融金属原料を保持する炉底及び側壁部からなる浴部と、装入原料を保持する上部水冷側壁部と、炉蓋とからなる。なお、以下において、浴部と上部水冷側壁部とを合せて炉本体と表記する場合もある。浴部の内面には耐火物が施工されており、耐火物炉壁を形成している。また、炉本体の開口部を覆う炉蓋には、炉本体内に挿入される電極が設けられている。   The electric furnace according to the present embodiment is an arc electric furnace, and melts a metal raw material using an arc generated between the metal raw material and an electrode. The furnace body of an electric furnace generally includes a bath part including a furnace bottom and a side wall part for holding a molten metal raw material, an upper water-cooled side wall part for holding a charged raw material, and a furnace lid. In the following description, the bath part and the upper water-cooled side wall part may be collectively referred to as a furnace body. A refractory material is applied to the inner surface of the bath portion to form a refractory furnace wall. Moreover, the electrode inserted in a furnace main body is provided in the furnace cover which covers the opening part of a furnace main body.

電気炉を平面視すると、図１に示すように、金属原料５を収容し、溶解した金属原料５が排出される出湯口１２を有する炉本体１０の中央部に、例えば３本の電極２１、２３、２５が配置される。炉本体１０の内面には、耐火物炉壁１４が設けられている。また、本実施形態に係る電気炉は、金属原料と電極との間で生じるアークの輻射熱を大きく受ける、炉本体１０と径方向に電極２１、２３、２５と対向する位置に、耐火物炉壁１４の表面の温度を測定する温度測定部３０Ａ、３０Ｂ、３０Ｃ（まとめて「温度測定部３０」とも称する。）が設けられている。   When the electric furnace is viewed in plan, as shown in FIG. 1, for example, three electrodes 21, in the central portion of the furnace main body 10 that contains the metal raw material 5 and has the outlet 12 from which the molten metal raw material 5 is discharged, 23 and 25 are arranged. A refractory furnace wall 14 is provided on the inner surface of the furnace body 10. In addition, the electric furnace according to the present embodiment receives a large amount of arc radiant heat generated between the metal raw material and the electrode, and the refractory furnace wall at a position facing the furnace body 10 and the electrodes 21, 23, 25 in the radial direction. 14 are provided with temperature measuring units 30A, 30B, and 30C (collectively referred to as “temperature measuring unit 30”).

温度測定部３０（３０Ａ、３０Ｂ、３０Ｃ）は、図２に示すように、それぞれ３つの熱電対３１、３３、３５により構成されている。熱電対３１、３３、３５は、炉本体１０と、炉本体１０の内面に施工されたパーマ耐火物１４ａ及びウェア耐火物１４ｂとを貫通して、先端部がウェア耐火物１４ｂ内に位置するように設けられる。各熱電対３１、３３、３５の先端部は、炉本体１０の径方向におけるパーマ耐火物１４ａの表面からの距離Ｌ１、Ｌ２、Ｌ３が異なるように配置されている。これにより、温度測定部３０により測定する位置における炉内壁面の温度分布を推定することができる。温度測定部３０により測定された温度測定値は、電気炉の操業を制御する制御装置４０へ出力される。なお、本実施形態の温度測定部３０は、３つの熱電対３１、３３、３５により構成したが、本発明はかかる例に限定されず、複数の熱電対により構成されていればよい。 The temperature measuring unit 30 (30A, 30B, 30C) includes three thermocouples 31, 33, 35, respectively, as shown in FIG. The thermocouples 31, 33, and 35 pass through the furnace body 10 and the permanent refractory 14a and the wear refractory 14b installed on the inner surface of the furnace body 10, so that the tip portion is located in the wear refractory 14b. Is provided. The tips of the thermocouples 31, 33, and 35 are arranged such that the distances L 1 , L 2 , and L 3 from the surface of the permanent refractory 14 a in the radial direction of the furnace body 10 are different. Thereby, the temperature distribution of the furnace inner wall surface at the position measured by the temperature measuring unit 30 can be estimated. The temperature measurement value measured by the temperature measurement unit 30 is output to the control device 40 that controls the operation of the electric furnace. In addition, although the temperature measurement part 30 of this embodiment was comprised by the three thermocouples 31, 33, and 35, this invention is not limited to this example, What is necessary is just to be comprised by the some thermocouple.

このような電気炉による金属原料の溶解は、まず、炉本体に、スクラップ、合金鉄、鋳銑、粒鉄等の金属原料と、使石灰、石灰石、アルミナ、硅石等の副原料とを装入した後、炉蓋をかぶせ、電極を金属原料に向け近接させる。そして、電極に電圧を印加すると、炉本体内で金属原料と電極との間にアークが発生し、この際に生じるアーク熱によって金属原料が溶解される。さらに、ノズルを介して酸素を吹き込み、リン、珪素等の不純物の除去や炭素濃度の調整を行うとともに、溶融金属の温度を上昇させて金属原料の溶解を促進させる。   In the melting of metal raw materials using such an electric furnace, first, the raw metal materials such as scrap, alloy iron, cast iron, and granular iron and auxiliary raw materials such as lime, limestone, alumina, and meteorite are charged into the furnace body. After that, the furnace lid is put on and the electrode is brought close to the metal raw material. When a voltage is applied to the electrode, an arc is generated between the metal material and the electrode in the furnace body, and the metal material is melted by the arc heat generated at this time. Further, oxygen is blown through a nozzle to remove impurities such as phosphorus and silicon and to adjust the carbon concentration, and to increase the temperature of the molten metal to promote the dissolution of the metal raw material.

なお、電気炉の操業では、１回の金属原料装入から溶解までの処理を１チャージとして、金属原料装入から溶解までの処理が繰り返し行われる。   In the operation of the electric furnace, the process from the charging of the metal raw material to the melting is performed as one charge, and the processing from the charging of the metal raw material to the melting is repeatedly performed.

＜２．電気炉の操業方法＞
電気炉による金属原料の溶解において、金属原料がすべて溶解するまでは耐火物炉壁は金属原料に覆われているので、高電力で操業しても熱流束が小さいため、電気炉を高電力で操業可能である。しかし、金属原料がすべて溶解すると、耐火物炉壁はアークに曝され、電気炉を高電力で操業すると、耐火物炉壁が損耗してしまう。そこで、本実施形態では、以下の条件で電気炉の操業方法を行う。これにより、炉内影響に応じて耐火物が損耗しない範囲内で最大電力を投入して金属原料を溶解することができる。 <2. Electric furnace operation method>
In the melting of the metal raw material using an electric furnace, the refractory furnace wall is covered with the metal raw material until all the metal raw material is melted, so the heat flux is small even when operated at high power. It is possible to operate. However, when all the metal raw materials are melted, the refractory furnace wall is exposed to an arc, and when the electric furnace is operated at high power, the refractory furnace wall is worn out. Therefore, in this embodiment, the electric furnace operating method is performed under the following conditions. Accordingly, the metal raw material can be melted by applying maximum power within a range in which the refractory is not worn according to the influence in the furnace.

（Ａ）１チャージにおける耐火物炉壁の表面温度の最高到達温度
まず、１チャージにおける耐火物炉壁の表面温度の最高到達温度を１０００℃以上１８００℃以下とする。最高到達温度が１８００℃を超えると耐火物炉壁の表面温度が耐火物の融点に近くなり、強度が顕著に下がる。耐火物炉壁の強度が低下すると、溶湯あるいはスラグの飛散により、耐火物炉壁の溶損が顕著となる。したがって、耐火物炉壁の表面温度は１８００℃以下にすることが望ましい。一方、最高到達温度を１０００℃未満とすると高い生産性を得られない。これより、最高到達温度は１０００℃以上とすることが望ましい。 (A) Maximum reached temperature of the surface temperature of the refractory furnace wall in one charge First, the highest reached temperature of the surface temperature of the refractory furnace wall in one charge is set to 1000 ° C. or higher and 1800 ° C. or lower. When the maximum temperature reaches 1800 ° C., the surface temperature of the refractory furnace wall becomes close to the melting point of the refractory, and the strength is significantly reduced. When the strength of the refractory furnace wall is reduced, the refractory furnace wall is significantly melted due to scattering of molten metal or slag. Therefore, the surface temperature of the refractory furnace wall is desirably 1800 ° C. or lower. On the other hand, if the maximum temperature is less than 1000 ° C., high productivity cannot be obtained. Therefore, it is desirable that the maximum temperature is 1000 ° C. or higher.

耐火物炉壁の表面温度は、例えば図２に示した温度測定部３０により取得可能である。温度測定部３０は、先端部が耐火物炉壁１４の耐火物厚さ方向（すなわち、炉本体１０の径方向）の異なる位置となるように設置された複数の熱電対３１、３３、３５からなる。熱電対３１、３３、３５により測定された温度測定値は、制御装置４０へ出力される。制御装置４０は、これらの温度測定値に基づいて耐火物厚さ方向の温度勾配を演算し、耐火物炉壁１４の表面温度を推定する。このように耐火物厚さ方向の温度勾配を得ることで、当該温度勾配に基づき耐火物炉壁の表面温度をより正確に推定できる。なお、耐火物炉壁の表面温度の取得は、かかる方法に限定されず、例えば、表面温度を直接測定する方法、その他の適切な表面温度推定方法を用いてもよい。   The surface temperature of the refractory furnace wall can be acquired by, for example, the temperature measuring unit 30 shown in FIG. The temperature measurement unit 30 includes a plurality of thermocouples 31, 33, and 35 that are disposed so that the tip portion is located at a different position in the refractory thickness direction of the refractory furnace wall 14 (that is, the radial direction of the furnace body 10). Become. The temperature measurement values measured by the thermocouples 31, 33, and 35 are output to the control device 40. The control device 40 calculates a temperature gradient in the refractory thickness direction based on these temperature measurement values, and estimates the surface temperature of the refractory furnace wall 14. Thus, by obtaining the temperature gradient in the refractory thickness direction, the surface temperature of the refractory furnace wall can be estimated more accurately based on the temperature gradient. In addition, acquisition of the surface temperature of a refractory furnace wall is not limited to this method, For example, you may use the method of measuring a surface temperature directly, and another suitable surface temperature estimation method.

（Ｂ）耐火物炉壁表面から内部への熱流束
また、耐火物炉壁の表面温度が１０００℃以上１８００℃以下の範囲では、耐火物炉壁表面から炉本体内部への熱流束を１５０Ｍｃａｌ／ｍ２／ｈｏｕｒ以下とする。 (B) Heat flux from the surface of the refractory furnace wall to the inside In the range where the surface temperature of the refractory furnace wall is 1000 ° C. or higher and 1800 ° C. or lower, the heat flux from the surface of the refractory furnace wall to the inside of the furnace main body is 150 Mcal / m 2 / hour or less.

耐火物炉壁の表面温度が１０００℃以上１８００℃以下の範囲は、耐火物は、溶湯あるいはスラグの接触による溶損は顕著に発生しない範囲ではあるものの、耐火物炉壁自体の強度は低下する。このため、耐火物炉壁の表面温度が１０００℃以上１８００℃以下の範囲にあるときに、溶湯あるいはスラグの接触により急激に高温になると、局所的に熱膨張差が発生し、スポーリングと同様な熱応力が発生する。したがって、耐火物炉壁の表面温度が１０００℃以上１８００℃以下の範囲にあるときに耐火物炉壁の表面温度の急激な上昇が発生すると、耐火物炉壁の割れを誘発し、損耗が顕著となる。   In the range where the surface temperature of the refractory furnace wall is 1000 ° C. or higher and 1800 ° C. or lower, the refractory is in a range where the melt damage due to the contact with the molten metal or slag does not occur remarkably, but the strength of the refractory furnace wall itself decreases. . For this reason, when the surface temperature of the refractory furnace wall is in the range of 1000 ° C. or more and 1800 ° C. or less, if the temperature rapidly rises due to contact with the molten metal or slag, a difference in thermal expansion occurs locally, which is similar to that of spalling. Thermal stress is generated. Therefore, if the surface temperature of the refractory furnace wall suddenly rises when the surface temperature of the refractory furnace wall is in a range of 1000 ° C. or higher and 1800 ° C. or lower, cracking of the refractory furnace wall is induced and wear is remarkable. It becomes.

本願発明者らは、鋭意検討の結果、耐火物炉壁の表面温度が１０００℃以上１８００℃以下の範囲において、熱流束が１５０Ｍｃａｌ／ｍ２／ｈｒ以下では、上述した熱膨張差による耐火物炉壁の損耗を抑制できることを知見した。熱流束が１５０Ｍｃａｌ／ｍ２／ｈｒ以下の低位域では、温度勾配が緩やかであるため、局所的な熱膨張差が小さく、熱応力の発生も小さくなる。したがって、耐火物炉壁に割れが発生しにくくなる。一方、熱流束が１５０Ｍｃａｌ／ｍ２／ｈｒ超となると、耐火物炉壁の割れの発生が顕著となる傾向があり、耐火物炉壁の補修が頻繁に必要となる耐火物損耗速度となる。したがって、耐火物炉壁の表面温度が１０００℃以上１８００℃以下の範囲において、熱流束が１５０Ｍｃａｌ／ｍ２／ｈｒ以下となるように電気炉を操業することで、耐火物炉壁の寿命を向上することができる。 As a result of intensive studies, the inventors of the present invention have found that the refractory furnace due to the above-described difference in thermal expansion when the surface temperature of the refractory furnace wall is in the range of 1000 ° C. to 1800 ° C. and the heat flux is 150 Mcal / m 2 / hr or less. It was found that wall wear can be suppressed. In a low region where the heat flux is 150 Mcal / m 2 / hr or less, since the temperature gradient is gentle, the local difference in thermal expansion is small and the generation of thermal stress is also small. Therefore, cracks are less likely to occur in the refractory furnace wall. On the other hand, when the heat flux exceeds 150 Mcal / m 2 / hr, cracking of the refractory furnace wall tends to become prominent, resulting in a refractory wear rate that requires frequent repair of the refractory furnace wall. Therefore, by operating the electric furnace so that the heat flux is 150 Mcal / m 2 / hr or less when the surface temperature of the refractory furnace wall is 1000 ° C. or higher and 1800 ° C. or lower, the life of the refractory furnace wall is improved. can do.

耐火物炉壁表面から炉本体内部への熱流束は、上記耐火物炉壁の表面温度の測定と同様、例えば図２に示した温度測定部３０により取得可能である。先端部が耐火物炉壁１４の耐火物厚さ方向の異なる位置となるように設置された複数の熱電対３１、３３、３５により測定された温度測定値は、制御装置４０へ出力される。制御装置４０は、これらの温度測定値に基づいて耐火物厚さ方向の温度勾配を演算し、耐火物炉壁１４表面から炉本体１０内部への熱流束を推定する。例えば、所定のサンプリング時間（例えば、３００秒以下の任意の時間）で温度勾配を演算し、熱流束を推定する。あるいは、熱電対３１、３３、３５のうちいずれか２つの温度測定値を用いて、２点の温度測定値の経時変化から伝熱における逆問題解析を行い、熱流束を算出してもよい。なお、当該熱流束は、かかる方法に限定されず、その他の適切な表面温度推定方法及び熱流束推定方法を用いてもよい。   The heat flux from the surface of the refractory furnace wall to the inside of the furnace body can be acquired by, for example, the temperature measuring unit 30 shown in FIG. 2, similarly to the measurement of the surface temperature of the refractory furnace wall. The temperature measurement values measured by the plurality of thermocouples 31, 33, and 35 installed so that the tip portion is located at a different position in the refractory thickness direction of the refractory furnace wall 14 are output to the control device 40. The control device 40 calculates a temperature gradient in the refractory thickness direction based on these temperature measurement values, and estimates a heat flux from the surface of the refractory furnace wall 14 to the inside of the furnace body 10. For example, the temperature gradient is calculated at a predetermined sampling time (for example, an arbitrary time of 300 seconds or less), and the heat flux is estimated. Alternatively, by using any two temperature measurement values of the thermocouples 31, 33, and 35, an inverse problem analysis in heat transfer may be performed from a change with time of two temperature measurement values to calculate the heat flux. In addition, the said heat flux is not limited to this method, You may use the other suitable surface temperature estimation method and heat flux estimation method.

熱流束は、各温度測定部３０Ａ、３０Ｂ、３０Ｃそれぞれの温度測定値に基づいて取得される。そして、得られた熱流束から、各チャージにおける最大熱流束が決定される。   A heat flux is acquired based on each temperature measurement value of each temperature measurement part 30A, 30B, 30C. And the maximum heat flux in each charge is determined from the obtained heat flux.

＜３．まとめ＞
以上、本実施形態によれば、このように、耐火物炉壁の表面温度及び熱流束について上記の操業条件を満たすように電気炉を操業することで、耐火物炉壁の損耗を抑制しながら、可能な範囲で高電力で電気炉を操業することができる。また、可能な範囲内で高電力で電気炉を操業できるため、操業時間を短縮することができる。その結果、耐火物炉壁の損耗をより抑制でき、炉壁等からの放熱ロスの低減等の改善による製造コスト削減が可能となる。 <3. Summary>
As described above, according to the present embodiment, while operating the electric furnace so as to satisfy the above-described operational conditions for the surface temperature and heat flux of the refractory furnace wall, the wear of the refractory furnace wall is suppressed. The electric furnace can be operated with high power as much as possible. Moreover, since the electric furnace can be operated with high power within a possible range, the operation time can be shortened. As a result, the wear of the refractory furnace wall can be further suppressed, and the manufacturing cost can be reduced by improving the heat dissipation loss from the furnace wall and the like.

以下、本発明の電気炉の操業方法の有効性について検証した結果を示す。本検証では、１チャージの操業により、図１及び図２に示した電気炉を用いてスクラップとＣｒ含有合金とからなる金属原料を溶解し、９０ｔの溶湯を得た。このとき、電気炉に投入したトランス容量は９０ＭＶＡとした。そして、当該チャージと同様のチャージを繰り返し行い、１か月間、電気炉を操業させた。   Hereafter, the result verified about the effectiveness of the operating method of the electric furnace of this invention is shown. In this verification, a metal raw material composed of scrap and a Cr-containing alloy was melted using an electric furnace shown in FIG. 1 and FIG. At this time, the transformer capacity charged into the electric furnace was 90 MVA. And the charge similar to the said charge was repeated, and the electric furnace was operated for one month.

下記表１に示す実施例及び比較例について、上記の操業条件に電気炉を操業し、耐火物炉壁の損耗状態及び生産性を評価した。耐火物炉壁の損耗、１チャージの生産性、及び１か月の生産性に対する評価基準は以下のとおりである。   About the Example and comparative example which are shown in following Table 1, the electric furnace was operated on said operating conditions, and the wear state and productivity of the refractory furnace wall were evaluated. Evaluation criteria for refractory furnace wall wear, 1 charge productivity, and 1 month productivity are as follows.

［耐火物炉壁損耗の評価基準］
１００〜２００ｃｈ操業後の最大損耗量から算出した１チャージあたりの損耗量から算出される損耗速度により評価
○：損耗速度１．５ｍｍ／ｃｈ未満
×：損耗速度１．５ｍｍ／ｃｈ以上
［１チャージの生産性に対する評価基準］
１チャージあたりの金属原料の溶解時間により評価
◎：通電開始から通電終わりまでの時間が７５分未満
○：通電開始から通電終わりまでの時間が７５分以上９０分未満
×：通電開始から通電終わりまでの時間が９０分以上
［１か月の生産性に対する評価基準］
○：比較例１を基準とし、増産代が５％以上改善
×：比較例１を基準とし、増産代が５％未満 [Evaluation criteria for refractory furnace wall wear]
Evaluated by the wear rate calculated from the wear amount per charge calculated from the maximum wear amount after 100 to 200 ch operation ○: Wear rate less than 1.5 mm / ch ×: Wear rate of 1.5 mm / ch or more [1 charge Evaluation criteria for productivity]
Evaluation based on melting time of metal raw material per charge ◎: Time from the start of energization to the end of energization is less than 75 minutes ○: Time from the start of energization to the end of energization is 75 minutes or more and less than 90 minutes ×: From the start of energization to the end of energization 90 minutes or more [Evaluation criteria for monthly productivity]
○: Increase in production increase by 5% or more based on Comparative Example 1 ×: Increase in production increase by less than 5% based on Comparative Example 1

Figure 2018003063
Figure 2018003063

実施例１は、上述の実施形態に係る電子炉の操業方法を適用して１か月間操業した場合であり、各チャージの耐火物炉壁表面の最大到達温度は１０００℃以上１８００℃以下に収まっており、耐火物炉壁表面の最大熱流束は１５０Ｍｃａｌ／ｍ２／ｈｏｕｒ以下に収まっている。このように電気炉を操業した結果、耐火物炉壁の損耗、１チャージの生産性、及び１か月の生産性はいずれも良好な結果となった。 Example 1 is a case where the operation method of the electron furnace according to the above-described embodiment is applied for one month, and the maximum temperature reached on the surface of the refractory furnace wall of each charge is 1000 ° C. or more and 1800 ° C. or less. The maximum heat flux on the surface of the refractory furnace wall is within 150 Mcal / m 2 / hour or less. As a result of operating the electric furnace as described above, the refractory furnace wall was worn, the charge productivity, and the monthly productivity were all good.

一方、比較例１では、１か月の操業において耐火物炉壁表面の最大熱流束が１５０Ｍｃａｌ／ｍ２／ｈｏｕｒを超えたチャージがあり、比較例２では、１か月の操業において耐火物炉壁表面の最大到達温度が１８００℃を超えたチャージがあった。このため、比較例１、２は、１チャージ毎の生産性は実施例１よりも良好であったが、耐火物炉壁の損耗速度が速く、１ケ月あたりの補修時間が増大した。その結果、１か月の生産性としては実施例１よりも増産代は改善されなかった。 On the other hand, in Comparative Example 1, there was a charge in which the maximum heat flux on the surface of the refractory furnace wall exceeded 150 Mcal / m 2 / hour in one month of operation, and in Comparative Example 2, the refractory furnace in one month of operation. There was a charge in which the maximum temperature reached on the wall surface exceeded 1800 ° C. For this reason, in Comparative Examples 1 and 2, the productivity per charge was better than that in Example 1, but the wear rate of the refractory furnace wall was fast and the repair time per month was increased. As a result, the increase in production was not improved as compared with Example 1 as the productivity for one month.

また、比較例３では、１か月の操業において耐火物炉壁表面の最大到達温度が１０００℃以上となったチャージはなかった。したがって、耐火物炉壁の損耗は少ないものの、１チャージの生産性も低くなり、結果として１か月の生産性が実施例１よりも増産代は改善されなかった。   In Comparative Example 3, there was no charge in which the maximum temperature reached on the surface of the refractory furnace wall was 1000 ° C. or higher in one month of operation. Accordingly, although the wear of the refractory furnace wall is small, the productivity of one charge is also low, and as a result, the productivity for one month is not improved compared to the first embodiment.

以上より、上記の実施形態に係る電気炉の操業方法を適用することで、耐火物の損耗抑制と生産性向上とを両立できることが示された。   From the above, it has been shown that by applying the method for operating an electric furnace according to the above-described embodiment, it is possible to achieve both suppression of wear of refractory and improvement of productivity.

以上、添付図面を参照しながら本発明の好適な実施形態について詳細に説明したが、本発明はかかる例に限定されない。本発明の属する技術の分野における通常の知識を有する者であれば、特許請求の範囲に記載された技術的思想の範疇内において、各種の変更例または修正例に想到し得ることは明らかであり、これらについても、当然に本発明の技術的範囲に属するものと了解される。   The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

５ 金属原料
１０ 炉本体
１２ 出湯口
１４ 耐火物炉壁
２１、２３、２５ 電極
３０Ａ、３０Ｂ、３０Ｃ 温度測定部
３１、３３、３５ 熱電対
DESCRIPTION OF SYMBOLS 5 Metal raw material 10 Furnace main body 12 Outlet 14 Refractory furnace wall 21, 23, 25 Electrode 30A, 30B, 30C Temperature measurement part 31, 33, 35 Thermocouple

Claims (1)

炉本体の内面に耐火物を施工して形成された耐火物炉壁を有する電気炉の操業方法であって、
１チャージにおける前記耐火物炉壁の表面温度の最高到達温度を１０００℃以上１８００℃以下とし、
かつ、前記耐火物炉壁の前記表面温度が１０００℃以上１８００℃以下の範囲では、前記耐火物炉壁表面から前記炉本体内部への熱流束が１５０Ｍｃａｌ／ｍ２／ｈｏｕｒ以下となるようにして、
前記電気炉に装入された金属を溶解する、電気炉の操業方法。
A method of operating an electric furnace having a refractory furnace wall formed by constructing a refractory on the inner surface of the furnace body,
The maximum temperature of the surface temperature of the refractory furnace wall in one charge is 1000 ° C. or higher and 1800 ° C. or lower,
And, in the range where the surface temperature of the refractory furnace wall is 1000 ° C. or more and 1800 ° C. or less, the heat flux from the refractory furnace wall surface to the inside of the furnace body is 150 Mcal / m 2 / hour or less. ,
An electric furnace operating method for melting a metal charged in the electric furnace.
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Publication number Priority date Publication date Assignee Title
JP2020076121A (en) * 2018-11-07 2020-05-21 Ｄｏｗａメタルマイン株式会社 Pgm recovery metho
KR20210142168A (en) * 2019-04-19 2021-11-24 닛폰세이테츠 가부시키가이샤 Method for producing molten iron containing chromium

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020076121A (en) * 2018-11-07 2020-05-21 Ｄｏｗａメタルマイン株式会社 Pgm recovery metho
JP7213659B2 (en) 2018-11-07 2023-01-27 Ｄｏｗａメタルマイン株式会社 Recovery method of PGM
KR20210142168A (en) * 2019-04-19 2021-11-24 닛폰세이테츠 가부시키가이샤 Method for producing molten iron containing chromium
KR102556231B1 (en) * 2019-04-19 2023-07-18 닛폰세이테츠 가부시키가이샤 Method for producing chromium-containing molten iron

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