JP2004138317A

JP2004138317A - Refractory thickness measuring method, and abnormality detecting method and device

Info

Publication number: JP2004138317A
Application number: JP2002303309A
Authority: JP
Inventors: Akira Noma; 野間　彰; Tomohiro Harada; 原田　朋弘; Keita Inoue; 井上　敬太
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2002-10-17
Filing date: 2002-10-17
Publication date: 2004-05-13

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for measuring a thickness of a refractory with high accuracy with simple equipment without forming a large hole in a furnace, and detecting the abnormality caused by the decreased thickness of the refractory. <P>SOLUTION: Two or more electrodes composed of conductors are buried between the refractory pieces 24, in a state of being opposite to each other at a specific interval, the capacitance between the electrodes 12 is measured, an area of the electrode is calculated from the capacitance measured on the basis of relationship of the capacitance corresponding to a dielectric constant of the refractory and the area of the electrode, and the thickness of the refractory is derived from the area of the electrode. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、炉内の高温雰囲気により侵食される炉壁若しくは炉底耐火物の厚さを測定し、また耐火物の厚さの減少による異常を検知する方法及び装置に関する。
【０００２】
【従来の技術】
高炉の炉壁若しくは炉底は、鉄皮に囲繞された炉内壁をアルミナ酸化物系セラミックやカーボン等で形成された耐火レンガ、耐火キャスタブル等の耐火物により形成されている。かかる耐火物は高温雰囲気に晒されて侵食し、高炉の操業に伴い徐々に肉厚が減少する。耐火物厚さを測定することは、炉の寿命、補修時期を適切に把握する上で非常に重要であり、炉を円滑に稼動するためには耐火物厚さを精度良く測定することが要求される。
そのため、耐火物厚さを測定する技術が数多く提案されている。
【０００３】
例えば、特開平９−６１１４４号公報（特許文献１）に示される厚さ測定装置は、図８のように、電圧発生器により発生させた弾性波を弾性波送信子１０１により耐火物１００の表面に送信し、該弾性波によって生じた反射波を弾性波受信子１０２により受信するように構成され、弾性波を送信してから反射波を受信するまでの時間に基づき耐火物１００の厚さを算出することにより、耐火物厚みを簡便かつ正確に計測することができる。
【０００４】
また、超音波等の波を利用したシステムとして特開２０００−１０５１１６公報（特許文献２）は、炉壁に差込んだセラミック等の導波体に音波を若しくは電磁波等の波を発振し、前記導波体の炉内側端面で反射して受信した波の信号に基づき該導波体の長さを計算する構成となっている。
このように、耐火物を伝播する波を利用した技術は、例えば耐火物に挿入したプローブに高周波信号を入力し、入力端に戻ってきた反射信号を検出しその伝播速度から耐火物厚さを測定する方法（特許文献３：特開平１１−２６４７０６号公報）等にも用いられている。
【０００５】
一方、特開平８−２６１７４１号公報（特許文献４）には、前記技術のように同軸ケーブル、プローブ等を埋め込む必要のない耐火物厚さ測定方法が提案されている。かかる方法は、耐火物が侵食するとミューオン透過強度が増加する特性を利用し、ミューオン強度を検出することにより耐火物厚さを計測するもので、これによれば機器が経年変化する惧れがなく、何時でも高炉耐火物厚さを測定することが可能となる。
【０００６】
【特許文献１】
特開平９−６１１４４号公報
【特許文献２】
特開２０００−１０５１１６公報
【特許文献３】
特開平１１−２６４７０６号公報
【特許文献４】
特開平８−２６１７４１号公報
【０００７】
【発明が解決しようとする課題】
しかしながら、前記ミューオンの検出による厚さ測定方法は一般的でなく実現性に乏しく、また設備が大掛かりとなり設置コストが嵩む。
また、前記特開平９−６１１４４号公報のように高炉の炉壁外面から超音波を送受信する技術では、炉壁外面が高温になり超音波振動子の機能が低下し、正確な耐火物厚さを測定することは困難である。
さらに、前記特開２０００−１０５１１６公報及び特開平１１−２６４７０６号のように炉壁にプローブや導波体を挿入すると炉内耐火物に大きな貫通穴が必要となる。
従って本発明はかかる従来技術の問題に鑑み、炉内に大きな穴を開ける必要がなく、簡易な設備でかつ精度良く耐火物厚さを計測し、また耐火物の厚さの減少による異常を検知する方法及び装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明はかかる課題を解決するために、耐火物間に所定間隔を隔てて対向して２以上の導電体からなる電極を埋設し、該電極間の静電容量を計測した後、耐火物誘電率に応じた静電容量と電極面積との関係に基づき前記計測した静電容量から前記電極面積を算出し、該電極面積より耐火物厚さを導き出すことを特徴とする。
また、前記静電容量は、前記電極間に交番電圧（交流、高周波を含む）を印加することにより計測することが好適である。
【０００９】
かかる発明は、耐火物の厚み方向に挿入した２以上の電極間に交番電圧をかけ、例えばＬＣＲ計、ミリオーム計等で静電容量を測定することにより電極面積を求める。前記電極は、耐火物の侵食にともない損耗して面積が小さくなる。そこで、電極面積を求めることで耐火物厚さを測定でき、耐火物の侵食度合が把握できる。
一般に、静電容量は電極面積及び電極間距離との間に次式の関係が成り立つ。
Ｃ　＝　ε・Ｓ／ｄ　　　　　　　　　　　　　　　…（１）
ここで、Ｃは静電容量（ｐＦ）、εは誘電率、Ｓは電極面積（ｃｍ^２）、ｄは電極間距離（ｃｍ）である。
【００１０】
この式より、εは耐火物に固有の値で、かつ電極間距離ｄは固定値であるため、電極間の静電容量Ｃを計測することで電極面積Ｓを算出することができ、容易に電極長さ、即ち耐火物厚さを導き出すことができる。
また、前記式（１）より、電極面積Ｓは静電容量Ｃと比例関係にあるため、静電容量の減少比率から電極面積の減少比率を容易に推測することも可能である。このように、耐火物間に薄肉の電極を挿入するのみで容易にかつ精度良く耐火物厚さを測定することができ、耐火物に大きな穴を開ける必要もない。
【００１１】
また、耐火物間に所定間隔を隔てて対向して２以上の導電体からなる電極を埋設し、該電極間の静電容量を計測した後、該計測した静電容量と前記耐火物の許容限界厚みに対応する静電容量の閾値とを比較して、前記静電容量が前記閾値より小さい場合には前記耐火物が許容限界厚みに満たないことを通知しても良い。このように、許容限界厚みに対応する静電容量の閾値を予め設定し、該閾値と計測した静電容量とを比較して耐火物が許容限界厚みに満たないことを通知することで、炉の寿命、補修時期を的確に把握することができる。
【００１２】
さらに、耐火物厚さの測定装置として、耐火物間に所定間隔を隔てて対向して埋設した２以上の導電体からなる電極と、炉外に設置され前記電極と接続されて該電極間の静電容量を計測する静電容量計測器と、該静電容量計測器に接続した耐火物厚さ算出機と、を具備し、
前記耐火物厚さ算出機が、前記耐火物の誘電率に基づく静電容量と電極面積との関係が蓄積されている記憶部と、前記記憶部に蓄積された静電容量と電極面積との関係に基づき前記静電容量計測器で計測された静電容量から電極面積を算出し、該算出された電極面積から耐火物厚さを導き出す演算部と、を備え、
前記電極間の静電容量から耐火物厚さを導き出す構成としたことを特徴とする。
【００１３】
かかる発明は、耐火物厚み方向に挿入した２以上の電極間の静電容量を計測し、予め蓄積しておいた耐火物の誘電率に基づく静電容量と電極面積との関係、即ち前記式（１）の関係より電極面積を算出して耐火物厚さを導きだす構成となっており、これにより、容易にかつ精度良く耐火物厚さを測定することが可能となる。また、前記静電容量計測器は、交番電圧（交流、高周波を含む）を印加することにより電極間の静電容量を計測する構成とすることが好適である。
【００１４】
さらに、前記電極を炉壁垂直方向に各電極が対向するごとく複数配設し、各電極間の静電容量を計測して耐火物の垂直方向の厚さ分布を測定することにより、例えば炉内の溶融物の状態など、炉内状況を的確に把握することができる。
また、前記耐火物が炉壁に設けられた耐火レンガであって、前記電極を該耐火レンガの目地部に埋設することを特徴とする。このように、耐火レンガの目地部に電極を埋設することにより、電極の挿入孔を別に設ける必要がなく簡単にかかる装置を設置することができる。
【００１５】
また、耐火物間に所定間隔を隔てて対向して埋設した２以上の導電体からなる電極と、炉外に設置され前記電極に接続され該電極間の静電容量を計測する静電容量計測器と、該静電容量計測器に接続した耐火物厚さ算出機と、を具備し、
前記耐火物厚さ算出機が、前記耐火物の許容限界厚みに対応する静電容量の閾値を記憶する記憶部と、前記静電容量計測器で検出された静電容量を前記閾値と比較する判定部と、を備え、
前記電極間の静電容量が前記閾値より小さい場合には前記判定部にて耐火物が許容限界厚みに満たないことを通知することを特徴とする。
【００１６】
このように、予め前記耐火物の許容限界厚みに対応する静電容量の閾値を設定し、前記計測した静電容量と前記閾値を比較することにより炉の寿命、補修時期を簡単に把握することができる。
尚、計測した静電容量が前記閾値より小である場合には炉の運転を停止、若しくは炉への供給電力を低下させ、大である場合には定常運転を続行することが好ましい。
【００１７】
また、炉外から炉内へ向けて耐火物間に挿入した光ファイバーと、炉外に設置し該光ファイバーにパルス状のレーザー光を発振するレーザー発振器と、該レーザー光により発生した散乱光を前記光ファイバーを介して受光する光検出器と、該検出された散乱光を受光する時間間隔を計測し、該計測された時間間隔に基づき光ファイバー長を算出する算出部と、を備え、
前記耐火物の侵食に伴い変化した光ファイバー長さを算出して、前記耐火物厚さを導き出すことを特徴とする。
【００１８】
かかる発明は、例えば炉外から炉内へ向けて耐火レンガの目地部に埋設した光ファイバーにパルス状のレーザー光を発振した後、該光ファイバーの先端部で反射した散乱光を受光し、前記発振から受光までの時間間隔から光ファイバー長を算出することにより耐火物厚さを測定する。このように、耐火物の侵食とともに損耗した光ファイバー長を測定することで簡単に耐火物厚さを導き出すことができる。また、前記光ファイバーは小径であるため、耐火物に大きな穴を開ける必要がなく目地部に埋設することもできる。このとき、前記光ファイバーを炉壁に複数設けても良く、耐火物厚さ分布を把握することも可能である。
【００１９】
さらにまた、前記光検出器で検出された散乱光に基づき、光ファイバー内各部の温度を算出する温度計測手段を備え、前記耐火物厚さとともに耐火物内の温度分布を計測することが好適である。これは、耐火物はある一定温度以上になると侵食が急激に進行するため、耐火物厚さとともに耐火物内の温度分布を計測することにより、耐火物の侵食を事前に予測することができる。
【００２０】
【発明の実施の形態】
以下、図面を参照して本発明の好適な実施例を例示的に詳しく説明する。但しこの実施例に記載されている構成部品の寸法、材質、形状、その相対的配置等は特に特定的な記載がない限りは、この発明の範囲をそれに限定する趣旨ではなく、単なる説明例に過ぎない。
図１及び図２は本発明の第１及び第２実施形態に係る耐火物厚さ測定装置の断面図（ａ）、及びＡ−Ａ、Ｂ−Ｂ線断面図（ｂ）、図４は本実施形態に係る耐火物厚さ測定装置を配設した溶融炉の全体概略図である。
【００２１】
図４において、２０は耐火物厚さ測定装置を配設したプラズマアーク式溶融炉で、溶融炉内側は絶縁性を有する耐火材２４及び炉底２５で形成され、炉外側は鉄皮２３で形成されている。そして、炉蓋に嵌挿された主電極２１と、炉底２５から挿入された炉底電極２２とを有し、これらに接続された直流電源２９により該電極間に電圧を印加してプラズマを生成し被溶融物を溶融処理する。炉内温度は１０００℃以上に維持され、炉底部には被溶融物が溶融したスラグ層２７と、その下部にメタル層２８とが層状に形成される。
【００２２】
前記耐火物２４は、一般にＳｉＣ等の材料を利用した耐火レンガを積層して目地で固定した構造を採っているが、前記スラグ層２７及びメタル層２８からなる高温流体の周囲に位置する耐火物２４は常時高温雰囲気に晒されるため侵食が著しい。
かかる実施形態における耐火物厚さ計測装置の電極１２は、特に侵食が著しい溶融スラグ層２７の周囲の耐火物２４に配設されることが好ましく、さらに目地２６に埋設することが好適である。これにより、耐火物に大きな穴を開ける必要がなく、また炉内に簡単に配設することができる。
【００２３】
本実施形態の耐火物厚さ計測装置は、炉内へ向けて耐火物厚さ方向に挿入した２以上の導電体からなる電極１２と、該電極１２に接続した同軸ケーブル１１と、該同軸ケーブル１１を介して電極１２に接続されたＬＣＲ計１０と、該ＬＣＲ計からの信号に基づき耐火物厚さを算出する耐火物厚さ算出機１３と、これに接続されて前記直流電源２９を制御する制御装置１４と、から構成されている。
図１（ａ）は図４の断面を示す拡大図で、耐火物２４の厚さ方向に前記スラグ層２７に接触する耐火物の侵食部３０に向けて挿入した少なくとも２枚の電極１２と、炉外部に設置されたＬＣＲ計１０とを同軸ケーブル１１で接続している。
【００２４】
本第１実施形態では図１（ｂ）に示されるように、前記電極１２をレンガ積み上げ方向の目地２６に垂直方向に対向して埋設している。該電極１２は、最も侵食が著しい溶融スラグ層２７に接触する耐火物に位置させることが好ましいが、特に限定されない。
前記ＬＣＲ計１０は、Ｌ（リアクタンス）、Ｃ（キャパシタンス）、Ｒ（レジスタンス）を測定可能で、前記電極１２に高周波若しくは交流等の電圧を印加することにより静電容量を計測する汎用装置である。かかる装置では、前記電極１２がコンデンサとして機能し、従来のコンデンサの静電容量測定と同様の手法で静電容量を計測できる。このとき、静電容量計測装置１０は前記ＬＣＲ計１０に限らず、例えばミリオーム計のように前記電極間の抵抗を計測し、該抵抗から静電容量を算出する装置でも良い。
【００２５】
また、かかる実施形態では、前記電極１２を垂直方向に複数設置して多層構造とし、夫々の静電容量を測定して炉壁耐火物の厚さ分布を測定することも可能である。
そして、前記計測された静電容量に基づき前記電極１２の面積を算出し、耐火物厚さを導き出す。前記電極１２は、高温流体との接触による耐火物２４の侵食に伴い損耗して面積が小さくなる。そこで本実施形態のごとく、電極１２の面積を求めることで耐火物２４の厚さを測定でき、耐火物の侵食度合を簡単に把握することができる。
【００２６】
図２は本発明の第２実施形態であって、炉内へ向けて挿入した導電体からなる電極１２を、炉の円周方向に対向させて２以上配設した構成としている。さらにかかる耐火物厚さ測定装置は、該電極１２に接続した同軸ケーブル１１と、該同軸ケーブル１１を介して電極１２に接続されたＬＣＲ計１０とを有している。
そして、前記第１実施形態と同様に、前記電極１２に交番電圧を印加して前記ＬＣＲ計１０にて静電容量を計測し、該静電容量から電極１２の面積を算出し、耐火物厚さを導きだす。
これにより、耐火物厚さを簡単に把握できるとともに、炉の円周方向に電極１２を配設しているため、対向した電極１２の損耗度合いが略同一で、より精度良く静電容量即ち耐火物厚さを測定することができる。
【００２７】
ここで、図５乃至図７に示される前記耐火物厚さ測定装置の詳細な構成及び処理動作を説明する。
図５に示されるように耐火物厚さ測定装置は、耐火物２４に配設された電極１２と、該電極１２に印加した交番電圧から静電容量を計測する静電容量計測装置１０と、該静電容量計測装置１０にて計測された静電容量と、予め記憶された耐火物の誘電率に応じた静電容量と電極面積との関係に基づき前記静電容量から耐火物厚さを算出する耐火物厚さ算出機１３と、から構成されている。
【００２８】
前記耐火物厚さ算出機１３は、次式（１）より関係付けられた静電容量と電極面積のデータが蓄積された記憶部１３ａと、前記計測された静電容量から記憶部１３ａに蓄積されたデータを基に電極面積を算出し、耐火物厚さを導き出す演算部１３ｂとを有している。
Ｃ　＝　ε・Ｓ／ｄ　　　　　　　　　　　　　　　…（１）
ここで、Ｃは静電容量（ｐＦ）、εは誘電率、Ｓは電極面積（ｃｍ^２）、ｄは電極間距離（ｃｍ）である。
【００２９】
この式より、εは耐火物に固有の値で、かつ電極間距離ｄは固定値であるため、電極間の静電容量Ｃを計測することで電極面積Ｓを算出することができ、容易に電極長さ、即ち耐火物厚さを導き出すことができる。
また、前記式（１）より、電極面積Ｓは静電容量Ｃと比例関係にあるため、静電容量の減少比率から電極面積の減少比率を容易に算出することも可能である。
このようにして出力された耐火物厚さにより、炉壁耐火物状態を的確に把握することができる。
【００３０】
図６は図５の別の実施形態を示し、図７はそのフローを示している。かかる実施形態によれば、炉の運転を開始し主電極及び炉底電極に一定電力を供給して定常運転を行い（Ｓ１）、所定時間間隔毎に前記電極１２に交番電圧を印加して静電容量計測装置１０にて電極間の静電容量を計測する（Ｓ２）。そして、予め記憶部１３ａ’に蓄積された耐火物の許容限界厚みに対応する静電容量の閾値と、前記計測された静電容量とを判定部１３ｂ’にて比較、判定する（Ｓ３）。尚、本実施形態では、耐火物厚さ算出機１３’は前記記憶部１３ａ’及び判定部１３ｂ’とで構成されている。
【００３１】
そして、前記静電容量が閾値以上である場合には定常運転（Ｓ１）を続行し、一方前記静電容量が閾値以下である場合には制御装置１４により直流電源への電力供給を停止若しくは低下させ、炉の運転を停止（Ｓ４）若しくは炉内温度を低下させる。
このように、予め前記耐火物の許容限界厚みに対応する静電容量の閾値を設定し、前記計測した静電容量と前記閾値を比較することにより炉の寿命、補修時期を簡単に把握することができる。
【００３２】
図３は本発明の第３実施形態に係る耐火物厚さ測定装置を示す。本第３実施形態に係る耐火物厚さ測定装置は、耐火物２４の目地部２６に埋設した光ファイバー１１’と、該光ファイバー１１’に接続され炉外に設置されたレーザー発振／受信器１０’と、から構成される。前記光ファイバー１１’は炉内へ向けて挿入され、侵食部３０で耐火物とともに侵食されて損耗する。
かかる実施形態では、前記レーザー発振／受信器１０’から光ファイバー１１’に導入したパルス状レーザ光の発振信号と、溶融スラグ２７面、即ち光ファイバー先端で反射した散乱光の受信信号から散乱光発生までの距離及び光ファイバー内部の温度分布を計測する。
前記光ファイバー１１’の材質は石英であるため腐食の惧れがなく、またスラグ２７に溶融しやすいため耐火物と共に侵食し、光ファイバー１１’を測定することで耐火物厚さを正確に測定することができる。
【００３３】
【発明の効果】
かかる発明によれば、耐火物間に薄肉の電極を挿入するのみで該電極間の静電容量から容易にかつ精度良く耐火物厚さを測定することができ、耐火物に大きな穴をあける必要もない。
また、電極を垂直方向若しくは炉壁円周方向に複数設置することで、耐火物の厚さ分布を簡単に把握することができる。
また、耐火物に挿入した光ファイバーにレーザー光を導入することで、その発振信号及び受信信号から光ファイバー長、即ち耐火物厚さを正確に測定することができるとともに、炉内耐火物の温度分布も同時に測定できる。
さらに、前記電極若しくは光ファイバーを耐火物の目地部に埋設することで、炉壁に穴を開ける必要がなく装置を炉内に簡単に設置することができる。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係る耐火物厚さ測定装置の断面図（ａ）、及びＡ−Ａ線断面図（ｂ）である。
【図２】本発明の第２実施形態に係る耐火物厚さ測定装置の断面図（ａ）、及びＢ−Ｂ線断面図（ｂ）である。
【図３】本発明の第３実施形態に係る耐火物厚さ測定装置の断面図（ａ）、及びＣ−Ｃ線断面図（ｂ）である。
【図４】本実施形態に係る耐火物厚さ測定装置を配設した溶融炉の全体概略図である。
【図５】本実施形態に係る耐火物厚さ測定装置の構成を示すブロック図である。
【図６】図５の別の実施形態に係る耐火物厚さ測定装置の構成を示すブロック図である。
【図７】図６の耐火物厚さ測定装置の処理動作を示すフローチャートである。
【図８】従来の耐火物厚さ測定装置を示す概要図である。
【符号の説明】
１０　　静電容量計測装置（ＬＣＲ計）
１０’　レーザー発振／受信機
１１　　同軸ケーブル
１１’　光ファイバー
１２　　電極
１３　　厚さ算出機
１４　　制御装置
２０　　プラズマアーク式溶融炉
２１　　主電極
２４　　耐火物
２６　　目地
２７　　溶融スラグ層
２８　　溶融メタル層
２９　　直流電源
３０　　侵食部[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method and an apparatus for measuring the thickness of a furnace wall or a bottom refractory eroded by a high-temperature atmosphere in a furnace and detecting an abnormality caused by a decrease in the thickness of the refractory.
[0002]
[Prior art]
The furnace wall or the bottom of the blast furnace is made of a refractory material such as a refractory brick, a refractory castable, or the like, in which a furnace inner wall surrounded by an iron shell is formed of alumina oxide ceramic, carbon, or the like. The refractory is exposed to a high-temperature atmosphere and erodes, and its thickness gradually decreases with the operation of the blast furnace. Measuring the thickness of refractory is very important in properly grasping the life and repair time of the furnace, and accurate measurement of the thickness of refractory is required for smooth operation of the furnace. Is done.
Therefore, many techniques for measuring the thickness of the refractory have been proposed.
[0003]
For example, a thickness measuring device disclosed in Japanese Patent Application Laid-Open No. 9-61144 (Patent Document 1) uses an elastic wave transmitter 101 to generate an elastic wave generated by a voltage generator, as shown in FIG. And the reflected wave generated by the elastic wave is received by the elastic wave receiver 102, and the thickness of the refractory 100 is determined based on the time from transmitting the elastic wave to receiving the reflected wave. By calculating, the thickness of the refractory can be measured simply and accurately.
[0004]
Japanese Patent Application Laid-Open No. 2000-105116 (Patent Document 2) discloses a system using a wave such as an ultrasonic wave that oscillates a sound wave or a wave such as an electromagnetic wave to a waveguide body such as a ceramic inserted into a furnace wall. The length of the waveguide is calculated based on the signal of the wave received and reflected at the furnace inner end face of the waveguide.
As described above, the technique using the wave propagating in the refractory is, for example, to input a high-frequency signal to a probe inserted in the refractory, detect a reflected signal returned to the input end, and determine the thickness of the refractory from the propagation speed. It is also used in a method for measuring (Patent Document 3: JP-A-11-264706).
[0005]
On the other hand, Japanese Unexamined Patent Application Publication No. 8-261174 (Patent Document 4) proposes a refractory thickness measuring method that does not require embedding a coaxial cable, a probe, or the like as in the above-described technique. Such a method utilizes the characteristic that the muon transmission intensity increases when the refractory erodes, and measures the thickness of the refractory by detecting the muon intensity, which eliminates the risk of equipment aging. In any case, the thickness of the blast furnace refractory can be measured.
[0006]
[Patent Document 1]
JP-A-9-61144 [Patent Document 2]
JP 2000-105116 A [Patent Document 3]
JP-A-11-264706 [Patent Document 4]
Japanese Patent Application Laid-Open No. 8-261174
[Problems to be solved by the invention]
However, the thickness measurement method based on the detection of muons is not general and is not feasible, and the equipment is large and the installation cost is high.
In the technology of transmitting and receiving ultrasonic waves from the outer wall of the furnace wall of the blast furnace as disclosed in Japanese Patent Application Laid-Open No. 9-61144, the outer wall surface of the furnace becomes high temperature, the function of the ultrasonic vibrator is reduced, and the accurate refractory thickness is reduced. Is difficult to measure.
Furthermore, when a probe or a waveguide is inserted into the furnace wall as in JP-A-2000-105116 and JP-A-11-264706, a large through hole is required in the refractory in the furnace.
Therefore, in view of the problems of the prior art, the present invention eliminates the need to make a large hole in the furnace, measures the thickness of the refractory accurately with simple equipment, and detects an abnormality caused by a decrease in the thickness of the refractory. It is an object of the present invention to provide a method and an apparatus for performing the above.
[0008]
[Means for Solving the Problems]
In order to solve this problem, the present invention embeds electrodes made of two or more conductors facing each other at a predetermined interval between refractories, measures the capacitance between the electrodes, and then sets the refractory dielectric. The electrode area is calculated from the measured capacitance based on the relationship between the capacitance and the electrode area according to the ratio, and the refractory thickness is derived from the electrode area.
Preferably, the capacitance is measured by applying an alternating voltage (including alternating current and high frequency) between the electrodes.
[0009]
In this invention, an alternating voltage is applied between two or more electrodes inserted in the thickness direction of the refractory, and the electrode area is determined by measuring the capacitance using, for example, an LCR meter, a milliohm meter, or the like. The area of the electrode is reduced due to wear due to the erosion of the refractory. Therefore, by determining the electrode area, the thickness of the refractory can be measured, and the degree of erosion of the refractory can be grasped.
In general, the following relationship holds between the capacitance and the electrode area and the distance between the electrodes.
C = ε · S / d (1)
Here, C is the capacitance (pF), ε is the dielectric constant, S is the electrode area (cm ² ), and d is the distance between the electrodes (cm).
[0010]
From this equation, ε is a value specific to the refractory, and the distance d between the electrodes is a fixed value. Therefore, by measuring the capacitance C between the electrodes, the electrode area S can be calculated, so that The electrode length, ie the refractory thickness, can be derived.
Also, from the above equation (1), since the electrode area S is proportional to the capacitance C, the reduction rate of the electrode area can be easily estimated from the reduction rate of the capacitance. As described above, the thickness of the refractory can be measured easily and accurately only by inserting the thin electrode between the refractories, and there is no need to make a large hole in the refractory.
[0011]
In addition, electrodes made of two or more conductors are buried facing each other at a predetermined interval between the refractories, and the capacitance between the electrodes is measured. A comparison may be made with a threshold value of the capacitance corresponding to the limit thickness, and when the capacitance is smaller than the threshold value, it may be notified that the refractory does not reach the allowable limit thickness. In this manner, the threshold of the capacitance corresponding to the allowable limit thickness is set in advance, and the threshold is compared with the measured capacitance to notify that the refractory is less than the allowable limit thickness. It is possible to accurately grasp the service life and repair time.
[0012]
Further, as a refractory thickness measuring device, an electrode made of two or more conductors buried facing each other at a predetermined interval between the refractory, and installed outside the furnace and connected to the electrode, between the electrodes A capacitance measuring device for measuring the capacitance, and a refractory thickness calculator connected to the capacitance measuring device,
The refractory thickness calculator, a storage unit in which the relationship between the capacitance and the electrode area based on the dielectric constant of the refractory is stored, and the capacitance and the electrode area stored in the storage unit Calculating an electrode area from the capacitance measured by the capacitance measuring device based on the relationship, and a calculation unit for deriving a refractory thickness from the calculated electrode area,
The thickness of the refractory is derived from the capacitance between the electrodes.
[0013]
This invention measures the capacitance between two or more electrodes inserted in the thickness direction of the refractory, and determines the relationship between the capacitance based on the dielectric constant of the refractory stored in advance and the electrode area, that is, the above equation. The structure is such that the electrode area is calculated from the relationship (1) to derive the thickness of the refractory, and thereby the thickness of the refractory can be measured easily and accurately. Further, it is preferable that the capacitance measuring device measures the capacitance between the electrodes by applying an alternating voltage (including alternating current and high frequency).
[0014]
Further, by arranging a plurality of the electrodes such that the electrodes face each other in the furnace wall vertical direction, measuring the capacitance between the electrodes and measuring the vertical thickness distribution of the refractory, for example, in the furnace The state of the furnace, such as the state of the melt, can be accurately grasped.
Further, the refractory is a refractory brick provided on a furnace wall, and the electrodes are embedded in joints of the refractory brick. By embedding the electrodes in the joints of the refractory bricks in this way, it is not necessary to separately provide an electrode insertion hole, and such an apparatus can be easily installed.
[0015]
An electrode made of two or more conductors buried facing each other at a predetermined interval between the refractories, and a capacitance measurement installed outside the furnace and connected to the electrodes and measuring the capacitance between the electrodes. Device, and a refractory thickness calculator connected to the capacitance measuring device,
The refractory thickness calculator, a storage unit that stores a capacitance threshold corresponding to the allowable limit thickness of the refractory, and compares the capacitance detected by the capacitance measuring device with the threshold. A determination unit;
When the capacitance between the electrodes is smaller than the threshold value, the determination unit notifies that the refractory is less than the allowable limit thickness.
[0016]
As described above, the threshold of the capacitance corresponding to the allowable limit thickness of the refractory is set in advance, and the life of the furnace and the repair time can be easily grasped by comparing the measured capacitance with the threshold. Can be.
When the measured capacitance is smaller than the threshold value, it is preferable to stop the operation of the furnace, or to reduce the power supplied to the furnace, and to continue the steady operation when the measured capacitance is large.
[0017]
Further, an optical fiber inserted between the refractory from outside the furnace to the inside of the furnace, a laser oscillator installed outside the furnace and oscillating a pulsed laser light on the optical fiber, and scattered light generated by the laser light is transmitted to the optical fiber. A photodetector that receives light through the, and measures a time interval for receiving the detected scattered light, and a calculating unit that calculates an optical fiber length based on the measured time interval,
The thickness of the refractory is calculated by calculating the length of the optical fiber that changes with the erosion of the refractory.
[0018]
This invention, for example, after oscillating pulsed laser light on the optical fiber buried in the joint of the refractory brick from the outside of the furnace toward the inside of the furnace, receives the scattered light reflected at the tip of the optical fiber, from the oscillation The thickness of the refractory is measured by calculating the optical fiber length from the time interval until light reception. As described above, the thickness of the refractory can be easily derived by measuring the length of the optical fiber that has been worn away with the erosion of the refractory. Further, since the optical fiber has a small diameter, it is not necessary to make a large hole in the refractory, and the optical fiber can be embedded in the joint. At this time, a plurality of the optical fibers may be provided on the furnace wall, and the refractory thickness distribution can be grasped.
[0019]
Furthermore, it is preferable that the apparatus further includes a temperature measurement unit that calculates the temperature of each part in the optical fiber based on the scattered light detected by the photodetector, and measures the temperature distribution in the refractory along with the thickness of the refractory. . This is because the erosion of the refractory rapidly proceeds when the temperature reaches a certain temperature or higher. Therefore, the erosion of the refractory can be predicted in advance by measuring the temperature distribution in the refractory together with the thickness of the refractory.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Not just.
FIGS. 1 and 2 are cross-sectional views (a) of the refractory thickness measuring apparatus according to the first and second embodiments of the present invention, and cross-sectional views (b) along lines AA and BB, and FIG. 1 is an overall schematic view of a melting furnace provided with a refractory thickness measuring device according to an embodiment.
[0021]
In FIG. 4, reference numeral 20 denotes a plasma arc type melting furnace provided with a refractory thickness measuring device, wherein the inside of the melting furnace is formed of a refractory material 24 and a furnace bottom 25 having insulating properties, and the outside of the furnace is formed of an iron shell 23. Have been. It has a main electrode 21 inserted into the furnace lid and a furnace bottom electrode 22 inserted from the furnace bottom 25, and applies a voltage between the electrodes by a DC power supply 29 connected thereto to generate plasma. The generated material is melted. The temperature in the furnace is maintained at 1000 ° C. or higher, and a slag layer 27 in which the material to be melted is formed at the bottom of the furnace, and a metal layer 28 is formed below the slag layer 27.
[0022]
The refractory 24 generally has a structure in which refractory bricks made of a material such as SiC are laminated and fixed at joints, but the refractory located around a high-temperature fluid composed of the slag layer 27 and the metal layer 28 is used. Since 24 is constantly exposed to a high-temperature atmosphere, erosion is remarkable.
The electrode 12 of the refractory thickness measuring device in such an embodiment is preferably disposed on the refractory 24 around the molten slag layer 27 where erosion is particularly remarkable, and more preferably embedded in the joint 26. Thus, it is not necessary to make a large hole in the refractory, and the refractory can be easily disposed in the furnace.
[0023]
The refractory thickness measuring apparatus according to the present embodiment includes an electrode 12 made of two or more conductors inserted into a furnace in a refractory thickness direction, a coaxial cable 11 connected to the electrode 12, and a coaxial cable. An LCR meter 10 connected to the electrode 12 via the reference numeral 11; a refractory thickness calculator 13 for calculating a refractory thickness based on a signal from the LCR meter; And a control device 14 that performs the control.
FIG. 1A is an enlarged view showing a cross section of FIG. 4, wherein at least two electrodes 12 inserted toward the erosion portion 30 of the refractory in contact with the slag layer 27 in the thickness direction of the refractory 24, An LCR meter 10 installed outside the furnace is connected with a coaxial cable 11.
[0024]
In the first embodiment, as shown in FIG. 1B, the electrode 12 is buried vertically facing a joint 26 in the brick stacking direction. The electrode 12 is preferably located on a refractory which comes into contact with the molten slag layer 27 which is most eroded, but is not particularly limited.
The LCR meter 10 is a general-purpose device that can measure L (reactance), C (capacitance), and R (resistance), and measures capacitance by applying a high frequency or alternating voltage to the electrode 12. . In such an apparatus, the electrode 12 functions as a capacitor, and the capacitance can be measured by a method similar to the conventional method of measuring the capacitance of a capacitor. At this time, the capacitance measuring device 10 is not limited to the LCR meter 10, and may be a device that measures the resistance between the electrodes and calculates the capacitance from the resistance, such as a milliohm meter.
[0025]
In this embodiment, it is also possible to arrange a plurality of the electrodes 12 in the vertical direction to form a multilayer structure, and measure the respective capacitances to measure the thickness distribution of the furnace wall refractory.
Then, the area of the electrode 12 is calculated based on the measured capacitance, and the refractory thickness is derived. The electrode 12 is worn down due to the erosion of the refractory 24 due to the contact with the high-temperature fluid, and its area is reduced. Therefore, as in the present embodiment, the thickness of the refractory 24 can be measured by determining the area of the electrode 12, and the degree of erosion of the refractory can be easily grasped.
[0026]
FIG. 2 shows a second embodiment of the present invention, in which two or more electrodes 12 made of a conductor inserted into the furnace are arranged so as to face each other in the circumferential direction of the furnace. Further, the refractory thickness measuring device has a coaxial cable 11 connected to the electrode 12 and an LCR meter 10 connected to the electrode 12 via the coaxial cable 11.
Then, similarly to the first embodiment, an alternating voltage is applied to the electrode 12, the capacitance is measured by the LCR meter 10, the area of the electrode 12 is calculated from the capacitance, and the refractory thickness is calculated. I will guide you.
Thus, the thickness of the refractory can be easily grasped, and the electrodes 12 are arranged in the circumferential direction of the furnace. Object thickness can be measured.
[0027]
Here, the detailed configuration and processing operation of the refractory thickness measuring device shown in FIGS. 5 to 7 will be described.
As shown in FIG. 5, the refractory thickness measuring device includes an electrode 12 provided on the refractory 24, a capacitance measuring device 10 for measuring a capacitance from an alternating voltage applied to the electrode 12, The capacitance measured by the capacitance measuring device 10 and the refractory thickness from the capacitance based on the relationship between the capacitance and the electrode area according to the dielectric constant of the refractory stored in advance. And a refractory thickness calculator 13 to be calculated.
[0028]
The refractory thickness calculator 13 stores the capacitance and the electrode area data related by the following equation (1), and stores the data in the storage unit 13a from the measured capacitance. And an operation unit 13b for calculating an electrode area based on the obtained data and deriving a refractory thickness.
C = ε · S / d (1)
Here, C is the capacitance (pF), ε is the dielectric constant, S is the electrode area (cm ² ), and d is the distance between the electrodes (cm).
[0029]
From this equation, ε is a value specific to the refractory, and the distance d between the electrodes is a fixed value. Therefore, by measuring the capacitance C between the electrodes, the electrode area S can be calculated, so that The electrode length, ie the refractory thickness, can be derived.
Further, since the electrode area S is proportional to the capacitance C from the equation (1), the reduction rate of the electrode area can be easily calculated from the reduction rate of the capacitance.
From the refractory thickness output in this manner, the state of the furnace wall refractory can be accurately grasped.
[0030]
FIG. 6 shows another embodiment of FIG. 5, and FIG. 7 shows the flow thereof. According to this embodiment, furnace operation is started, constant power is supplied to the main electrode and the furnace bottom electrode to perform steady operation (S1), and an alternating voltage is applied to the electrode 12 at predetermined time intervals to statically operate. The capacitance between the electrodes is measured by the capacitance measuring device 10 (S2). Then, the determination unit 13b 'compares and determines the threshold value of the capacitance corresponding to the allowable limit thickness of the refractory previously stored in the storage unit 13a' and the measured capacitance (S3). In the present embodiment, the refractory thickness calculator 13 'includes the storage unit 13a' and the determination unit 13b '.
[0031]
When the capacitance is equal to or larger than the threshold, the steady operation (S1) is continued. On the other hand, when the capacitance is equal to or smaller than the threshold, the power supply to the DC power supply is stopped or reduced by the controller 14. Then, the operation of the furnace is stopped (S4) or the temperature in the furnace is decreased.
As described above, the threshold of the capacitance corresponding to the allowable limit thickness of the refractory is set in advance, and the life of the furnace and the repair time can be easily grasped by comparing the measured capacitance with the threshold. Can be.
[0032]
FIG. 3 shows a refractory thickness measuring apparatus according to a third embodiment of the present invention. The refractory thickness measuring apparatus according to the third embodiment includes an optical fiber 11 'embedded in a joint 26 of a refractory 24, and a laser oscillation / receiver 10' connected to the optical fiber 11 'and installed outside the furnace. And The optical fiber 11 ′ is inserted into the furnace, and is eroded with the refractory at the erosion portion 30 and is worn.
In this embodiment, the oscillation signal of the pulsed laser light introduced from the laser oscillation / receiver 10 'into the optical fiber 11' and the reception signal of the scattered light reflected from the surface of the molten slag 27, that is, the tip of the optical fiber, to the generation of scattered light. And the temperature distribution inside the optical fiber are measured.
Since the material of the optical fiber 11 'is quartz, there is no fear of corrosion, and since the material is easily melted in the slag 27, it erodes together with the refractory, and the thickness of the refractory is accurately measured by measuring the optical fiber 11'. Can be.
[0033]
【The invention's effect】
According to the invention, it is possible to easily and accurately measure the thickness of the refractory from the capacitance between the electrodes simply by inserting a thin electrode between the refractories, and it is necessary to make a large hole in the refractory. Nor.
In addition, by disposing a plurality of electrodes in the vertical direction or the circumferential direction of the furnace wall, the thickness distribution of the refractory can be easily grasped.
In addition, by introducing a laser beam into the optical fiber inserted into the refractory, the length of the optical fiber, that is, the thickness of the refractory can be accurately measured from the oscillation signal and the received signal, and the temperature distribution of the refractory in the furnace can also be measured. Can be measured at the same time.
Further, by embedding the electrode or the optical fiber in the joint of the refractory, it is not necessary to make a hole in the furnace wall, and the apparatus can be easily installed in the furnace.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view of a refractory thickness measuring apparatus according to a first embodiment of the present invention, and FIG.
FIG. 2 is a sectional view (a) of a refractory thickness measuring apparatus according to a second embodiment of the present invention, and a sectional view taken along the line BB (b).
3A is a cross-sectional view of a refractory thickness measuring apparatus according to a third embodiment of the present invention, and FIG. 3B is a cross-sectional view taken along line CC.
FIG. 4 is an overall schematic diagram of a melting furnace provided with the refractory thickness measuring device according to the present embodiment.
FIG. 5 is a block diagram illustrating a configuration of a refractory thickness measuring device according to the present embodiment.
FIG. 6 is a block diagram showing a configuration of a refractory thickness measuring apparatus according to another embodiment of FIG. 5;
FIG. 7 is a flowchart showing a processing operation of the refractory thickness measuring device of FIG. 6;
FIG. 8 is a schematic diagram showing a conventional refractory thickness measuring device.
[Explanation of symbols]
10 Capacitance measuring device (LCR meter)
Reference Signs List 10 'laser oscillation / receiver 11 coaxial cable 11' optical fiber 12 electrode 13 thickness calculator 14 controller 20 plasma arc type melting furnace 21 main electrode 24 refractory 26 joint 27 molten slag layer 28 molten metal layer 29 DC power supply 30 erosion Department

Claims

An electrode made of two or more conductors is buried facing each other at a predetermined interval between the refractories, and after measuring the capacitance between the electrodes, the capacitance and the electrode area according to the dielectric constant of the refractory are measured. A refractory thickness measuring method, wherein the electrode area is calculated from the measured capacitance based on the relationship, and the refractory thickness is derived from the electrode area.

The refractory thickness measuring method according to claim 1, wherein the capacitance is measured by applying an alternating voltage (including alternating current and high frequency) between the electrodes.

After embedding electrodes made of two or more conductors facing each other at a predetermined interval between the refractories, measuring the capacitance between the electrodes, the measured capacitance and the allowable limit thickness of the refractory are measured. Comparing with a threshold value of the capacitance corresponding to the above, if the capacitance is smaller than the threshold value, it is notified that the refractory is less than the allowable limit thickness. Detection method.

An electrode made of two or more conductors buried facing each other at a predetermined interval between refractories, and a capacitance measuring instrument installed outside the furnace and connected to the electrode to measure a capacitance between the electrodes And a refractory thickness calculator connected to the capacitance measuring device,
The refractory thickness calculator, a storage unit in which the relationship between the capacitance and the electrode area according to the dielectric constant of the refractory is stored, the capacitance and the electrode area stored in the storage unit Calculating an electrode area from the capacitance measured by the capacitance measuring device based on the relationship of, and deriving a refractory thickness from the calculated electrode area,
A refractory thickness measuring apparatus, wherein the refractory thickness is derived from the capacitance between the electrodes.

The refractory thickness measuring apparatus according to claim 4, wherein the capacitance measuring device is configured to measure an electrostatic capacitance between the electrodes by applying an alternating voltage (including alternating current and high frequency). .

5. The method according to claim 4, wherein a plurality of the electrodes are arranged in such a manner that the electrodes face each other in a vertical direction of the furnace wall, and a capacitance distribution between the electrodes is measured to measure a vertical thickness distribution of the refractory. Or the refractory thickness measuring device according to 5.

The refractory thickness measurement according to any one of claims 4 to 6, wherein the refractory is a refractory brick provided on a furnace wall, and the electrode is embedded in a joint of the refractory brick. apparatus.

An electrode made of two or more conductors buried facing each other at a predetermined interval between the refractories, and a capacitance measuring instrument installed outside the furnace and connected to the electrode and measuring the capacitance between the electrodes; A refractory thickness calculator connected to the capacitance measuring device,
The refractory thickness calculator, a storage unit that stores a capacitance threshold corresponding to the allowable limit thickness of the refractory, and compares the capacitance detected by the capacitance measuring device with the threshold. A determination unit;
If the capacitance between the electrodes is smaller than the threshold, the determination unit notifies the refractory that the thickness is less than an allowable limit thickness, and the refractory thickness abnormality detection device is characterized by the above-mentioned.

An optical fiber inserted between the refractories from outside the furnace to the inside of the furnace, a laser oscillator installed outside the furnace and oscillating pulsed laser light on the optical fiber, and scattered light generated by the laser light is transmitted through the optical fiber. And a photodetector that receives and detects the time interval for receiving the detected scattered light, and a calculating unit that calculates an optical fiber length based on the measured time interval,
An apparatus for measuring a thickness of a refractory, wherein a length of an optical fiber changed according to erosion of the refractory is calculated to derive the thickness of the refractory.

10. A temperature measuring means for calculating a temperature of each part in the optical fiber based on the scattered light detected by the photodetector, wherein the temperature distribution in the refractory is measured together with the thickness of the refractory. The refractory thickness measuring device according to the description.