JP3728050B2

JP3728050B2 - Blast furnace bottom condition estimation method

Info

Publication number: JP3728050B2
Application number: JP07711097A
Authority: JP
Inventors: 地厖菊; 村和人山
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1997-03-28
Filing date: 1997-03-28
Publication date: 2005-12-21
Anticipated expiration: 2017-03-28
Also published as: JPH10273708A

Description

【０００１】
【発明の属する技術分野】
本発明は、溶鉱炉（以下、高炉という）の炉底内部の状況推定方法に関し、特に、高炉の操業管理ならびに炉底耐火物寿命診断のため、炉底耐火物の浸食状況，及び炉底耐火物内面に付着している内容物の形成の状況を把握する方法に関するものである。
【０００２】
【従来の技術】
一般的な高炉の炉底の状況を、図１に模式的に示す。高炉における耐火物の浸食後（浸食部分４）の健全部２の残存厚さならびに耐火物内面に付着する内容物の凝固層３の厚さを、図１に示すように炉底耐火物内に設置された温度センサー９、９ａ、９ｂ、９ｃなどにより測定された実測値を用いた伝熱計算によって推定する従来方法は、具体的には次のようなものである。すなわち、耐火物内に設置された温度センサーによる実測値のうち最高温度への到達値と鉄皮１の表面５の温度あるいは鉄皮表面における伝熱条件から、炉底耐火物の浸食形状６（通常はこの部分の温度は溶銑の凝固点温度である１１５０°Ｃである）を一次元的に決定し、残存厚さを求めるものである。
【０００３】
しかし、このような従来の推定方法は、一次元的であるため、実際の炉底の解体調査時に見られる炉底耐火物の浸食形状が曲線状の複雑な形状である事実と推定形状が合わないことが多く、炉底耐火物の健全部２の残存厚さの推定精度に問題があった。
【０００４】
これを解決する方法として、炉底耐火物浸食形状を連続ラインと仮定し、二次元的に差分法や有限要素法を用いて逐次的に求め、実測温度を再現する浸食形状を決定し、炉底耐火物の残存厚さを推定することが行われている。例えば、特公昭５７−５１４４５号公報に開示された発明では、実測値の温度と計算値である推定基準温度の差を用いて、先に仮定した耐火物の浸食形状を補正することにより、実際の浸食形状を求めている。
【０００５】
また、特公昭６１−３７３２８号公報に開示された発明では、境界要素法と数理計画法を組み合わせて、炉底耐火物の浸食形状や炉内内容物の凝固形状を推定している。また、特開平７−２７８６３２号公報に開示された発明では、有限要素法と最適化手法の一つである遺伝的アルゴリズムを用いて、炉底耐火物と内容物の分布状態を最適化することによって、炉底耐火物の浸食形状や炉内内容物の凝固形状を推定している。
【０００６】
【発明が解決しようとする課題】
しかしながら、先に述べたように、炉底耐火物の浸食形状や炉底耐火物表面に付着した炉内内容物の凝固層の形状の、従来技術による推定方法には、以下のような問題がある。
【０００７】
（ａ）まず、従来技術による推定方法では、実測値の炉底温度の値は最高温度に達した値だけを採用し、また伝熱計算においては、時間に依存しない定数の状態としての計算であることが問題である。実際は図２に示すように、炉底（図１の９ａ部）の実測温度は時間に依存して変化しており、最も耐火物の残存厚を管理したい時期である浸食が進んで耐火物の残存厚が薄くなってきた場合には、実測値の温度の時間に依存する変化がさらに大きくなり、しかも、図１に示す高炉の円筒状の側面には熱伝導率の高い材質の耐火物を用いることが多いことも影響して、従来技術による推定方法のように定常の状態として計算した場合には、炉底耐火物の残存厚さや耐火物表面に付着した炉内内容物の凝固層の厚さの推定を誤ることになる。つまり、ある時刻での実際の高炉半径方向の温度分布，耐火物の実際の厚さ，耐火物の実際の内表面位置１１が図３に示すような場合でも、耐火物の外表面である０点、耐火物の内部のａ点、耐火物の内表面であるｓ’点の実際と同じ温度を用いて定常計算で推定した場合は、その推定温度分布は図３の破線のようになり、Ｓ’と同じ温度Ｓ”でありながらその厚さの内表面位置は１２のように実際の位置１１と異なる結果になる。
【０００８】
（ｂ）また、従来技術による推定方法では、伝熱計算において、図１に示すように、炉底耐火物の健全部分２の他には炉底耐火物表面に付着した炉内内容物３が一種類存在するとして物性値を決め、その生成と消滅は温度の大きさに応じて炉内内容物の表面７のラインを連続的に移動させる方法を採用しいてるが、これも問題である。図４に示すように、実際の高炉炉底の解体調査から、前記炉内内容物３は２種類（３ａ，３ｂ）以上の材質のものから構成されていること、また実測値の炉底温度は、図２に示すように、長時間に渡って安定した状態から急激に上昇する場合があり、伝熱計算結果と一致せず、結果として炉底耐火物の浸食形状６や炉底耐火物表面に付着した炉内内容物３の凝固層の厚さの推定を誤ることになる。
【０００９】
そこで、本発明は、炉底温度の実測値が時間に依存して大きく変化する場合や炉内の内容物が生成と消滅を起こす場合でも、耐火物の残存厚さと内容物の層の厚さを推定することができる高炉炉底状況の推定方法を提供することを目的とするものである。
【００１０】
【課題を解決するための手段】
本発明の要旨は、高炉炉底の耐火物の損耗時期と残存厚さならびに耐火物内面に付着する内容物凝固層の生成・消滅時期と残存厚さを、高炉炉底に設置された温度センサーの実測値を用いて伝熱計算によって推定する方法において、以下の手順を特徴とする高炉炉底状況の推定方法である。
【００１１】
（Ａ）：高炉炉底構造の伝熱解析を行うため、炉底構造を以下のような５層、すなわち、
（ａ）健全な耐火物の層、
（ｂ）健全な耐火物以外の耐火物の層、
（ｃ）凝固した銑鉄の層、
（ｄ）固体と液体の共存している銑鉄の層、
（ｅ）流れの速度がゼロの溶融銑鉄の層
から構成されるモデルを作り、各々の層に厚さと物性値を付与する；
（Ｂ）：炉底耐火物内に設置された複数の温度センサーにより測定された炉底耐火物の温度の時系列データを実測値の炉底温度とする；
（Ｃ）：該モデルに、経過時間に依存する非定常の伝熱解析を実施する；
（Ｄ）：解析結果の温度の大きさによって、（Ａ）の各層を、生成あるいは消滅させるが、その時、生成させる限界温度と消滅させる限界温度は同一値または異なる値とする；
（Ｅ）：（Ｃ）へ戻り、計算する所定の経過時間に達するまで（Ｃ）、（Ｄ）を繰り返して、計算値として得られた温度分布のうち、（Ｂ）の実測値の炉底温度と同位置でかつ所定の経過時間までの計算結果の時系列の温度値を、計算値の炉底温度とする；
（Ｆ）：（Ｂ）による実測値の炉底温度と（Ｅ）による計算値の炉底温度の極小値及び極大値、並びに温度上昇率及び温度下降率、並びに温度上昇加速度及び温度下降加速度を所定の期間内で比較する；
（Ｇ）：（Ａ）へ戻り、（Ｆ）での実測値の炉底温度と計算値の炉底温度との比較の差に従って、５種類の材質の層の厚さを変えて再び（Ｃ）以下の手順を、（Ｆ）による実測値の炉底温度と計算値の炉底温度の差が所定の値以下になるまで繰り返す；
（Ｈ）：（Ｇ）においての繰り返し計算が終了した時の（Ａ）における５種類の（厚さゼロも含む）各層の厚さが求める炉底状況の最終状態とする。
【００１２】
【発明の実施の形態】
以下、本発明の実施の形態を詳細に説明する。本発明による高炉炉底状況の推定方法では、まず始めに、炉温度の実測データのうち、６時間以上に渡り安定した温度データ、すなわち図２の時刻０から時刻ｔ₀までのような温度データを用いて、図５に示した炉底構造のモデルの炉底耐火物の健全部分１７とその炉内側表面に付着した内容物の各層１３，１４，１５，１６の厚さを定常計算によって求め、その結果を以後の非定常計算の初期状態とする。
【００１３】
すなわち、図５のＴａの位置の温度センサー９で測定された図２の実測データと、予め容易に測ることができる図５の鉄皮の外面の温度Ｔ１を用いて、定常状態として熱貫流量を求めて、図５に示した炉底構造の伝熱計算のための多層のモデルの各物性値を与え、定常の伝熱計算を行い、各層の厚さを決める。
【００１４】
次に、図２に示した炉底温度の実測データの時刻ｔ₀からｔ₂までの例で示すような温度が上昇する過程、すなわち、耐火物の炉内側表面に付着した内容物あるいは健全な耐火物も含み消滅していく過程の温度データを用い、炉内側最内の内容物の層であるところの、流れの速度がゼロの溶融銑鉄の層１３の、炉内表面７の熱伝達率あるいは炉内熱源の温度の上昇開始を初期条件にし、前に求められている定常状態を初期状態にして、時間に関しての逐次計算、すなわち時刻歴過渡応答非定常伝熱解析を開始する。
【００１５】
引き続いて、計算する時刻に沿って逐一、健全耐火物と付着した内容物の各層の表面の温度、すなわち図５におけるＴｘ３，Ｔｘ２，Ｔｘ１，Ｔｍ，Ｔｃの位置の温度、および各層の物性値として予め定めた存在限界温度に当たる位置を探知し、各層の表面温度が該層の存在限界温度より高い値の場合は、図６に示すように、内容物の炉内側最内表面の最初の位置２１から該層の存在温度の深さ２２までの厚さ相当の層２０を削除または減少させたうえで、次の時刻に計算を進める。
【００１６】
以下、同様に繰り返して、どの層の表面も該層の存在限界温度と同等となるかあるいは、図２に示した実測データと同位置での計算結果を比較しながら実測データの極大値と同等になるまで計算を繰り返す。その結果が該時刻での炉底耐火物の健全部分の残存厚さ、あるいは耐火物健全部分の炉内側表面に付着した内容物が存在している場合はその残存厚さ、を示すことができる。
【００１７】
引き続いて、図２に示した炉底温度の実測データの時刻ｔ₂からｔ₃の例で示すような、温度が下降する過程、すなわち、耐火物の炉内側表面に内容物が生成していく過程の温度データを用い、炉内側最内の内容物の層であるところの、流れの速度がゼロの溶融銑鉄の層の炉内表面側の熱伝達率あるいは炉内熱源の温度の下降開始を初期条件にして、時間に関しての逐次計算、すなわち時刻歴過渡応答非定常伝熱解析を開始する。
【００１８】
引き続いて、計算する時刻に沿って逐一、炉内側最内表面の温度を参照し、物性値として予め定めた付着すべき内容物の各層の存在限界温度と比較し、健全な耐火物の表面も含み、内容物の炉内側最内表面の温度が付着すべき内容物の各層の存在限界温度より低い値の場合は、図７に示すように、計算値に最も近い値の存在限界温度を有する内容物の層２３を、健全な耐火物の表面あるいは内容物の炉内側最内表面２５に微小な厚さを生成させ、同時に、物性値として予め定めた各層の存在限界温度の位置を参照し、その位置から低温側の次の層の存在限界温度の位置２４までの厚さを該層の物性値に置き換えたうえで次の時刻に計算を進める。
【００１９】
以下、同様に繰り返して、どの層の表面も該層の存在限界温度と同等となるかあるいは、図２に示した実測データと同位置での計算結果を比較しながら実測データの極大値ｔ₂と同等になるまで計算を繰り返す。その結果が、該時刻での炉底耐火物の健全部分の残存厚さ、あるいは耐火物健全部分の炉内側表面に付着した内容物が存在している場合はその残存厚さ、を示すことになる。
【００２０】
【実施例】
内容積５０００ｍ³級の大型高炉で、図１の高炉炉底の温度計９ａの存在する部位すなわち側壁と呼ぶ部分について、本発明の高炉炉底状況の推定方法を適用した。解析に用いた実測データは、図１の９ａに相当する位置でのある期間の測定結果であり、図２に実線で示す。図５に相当する伝熱解析の多層モデルは、図８および表１に示すように各層に物性値を与え、最外壁の鉄皮１９（図８）の表面温度は実測値３０°Ｃを用いた。図８の中で図２の実測データの測定位置に対応する位置は、図８の計算モデルでの位置９ａであり、温度は計算結果としてのＴａである。計算手法は有限要素法を用いた。
【００２１】
【表１】

【００２２】
始めに、図２の実測データの初期の安定期間である時刻０からｔ₀におけるＴａの値および図８および表１に示した各層の物性値を用いて定常温度解析を行い、図８の各層の未知の厚さを決定する。すなわち、熱源と炉内側最内内容物の表面の間の熱伝達率α＝３８ｋｃａｌ／ｍ²／ｈｒ／°Ｃ、炉底耐火物の健全部分の厚さＬｃ＝７５０ｍｍ、健全な耐火物以外の耐火物の厚さＬｍ＝８４０ｍｍ、凝固した銑鉄の層の厚さＬｘ１＝１００ｍｍ、固体と液体の共存している銑鉄の層の厚さＬｘ２＝９８ｍｍ、流れの速度がゼロの溶融銑鉄の層の厚さＬｘ３＝６０２ｍｍが決まる。
【００２３】
引き続き、図２の実測データの温度上昇過程すなわち時刻ｔ₀からｔ₂について解析する。時刻ｔ₀からｔ₂の初期条件としては、熱源と炉内側最内内容物の表面の間の熱伝達率をα＝３８ｋｃａｌ／ｍ²／ｈｒ／°Ｃから１１５ｋｃａｌ／ｍ²／ｈｒ／°Ｃに上昇させ、時刻歴過渡応答非定常伝熱解析を開始する。時刻歴過渡応答計算での時刻刻みは１０分とした。
【００２４】
引き続いて、計算の時刻刻みの１０分毎に逐一、図８に示した各層の炉内側表面の温度、すなわち、炉内側最内表面の位置７すなわち流れの速度がゼロの溶融銑鉄の層１３の表面での温度Ｔｘ３，固体と液体の共存している銑鉄の層１４の表面温度Ｔｘ２，凝固した銑鉄の層１５の表面温度Ｔｘ１，健全な耐火物以外の耐火物の層１６の表面温度Ｔｍ、および、耐火物の健全部分の表面６の位置の温度Ｔｃを、各々の存在限界温度、すなわち、Ｔｘ３＝１３００°Ｃ，Ｔｘ２＝１１８０°Ｃ，Ｔｘ１＝１１５０°Ｃ，Ｔｍ＝１３００°Ｃ、および、Ｔｃ＝１１８０°Ｃと比較し、計算値が高い場合、内容物の層の炉内側最内表面の位置７から炉外側に向かって微小量厚さ（１０ｍｍ）を削除したうえで１０分間の非定常伝熱解析を行い、各層の炉内側表面の温度の計算値が各々の存在限界温度に等しいかそれ以下になる時刻まで、１０分当たり１０ｍｍづつの削除を繰り返し、計算を進める。
【００２５】
このようにして得られた図８の９ａにおける温度Ｔａの計算結果は、図２の本発明による計算結果を示す破線の時刻ｔ₀からｔ₂までで示す。また、各層の状態の計算結果、すなわち、図２の時刻ｔ₁における各層の残存状態は図９に、図２の時刻ｔ₂における各層の残存状態は図１０に、それぞれ示す。
【００２６】
引き続いて、図２の実測データの温度下降過程すなわち時刻ｔ₂からｔ₃について解析する。時刻ｔ₂からｔ₃の初期条件、すなわち図２の時刻ｔ₂は実際の操業において休風開始であったため、図８の熱源の温度Ｔｈを１５００°Ｃから１４７０°Ｃに下降させて、時刻歴過渡応答非定常伝熱解析を開始する。時刻歴過渡応答計算での時刻刻みは１０分とした。
【００２７】
引き続いて、計算の時間刻みの１０分毎に逐一、図１０に示した残存層すなわち残存した耐火物健全部分の炉内側最内表面位置７に、初期条件として微小量（１０ｍｍ）を付着させた、流れの速度がゼロの溶融銑鉄の層１３の表面温度Ｔｘ３の計算結果を探索して参照し、その存在限界温度１３００°Ｃと比較して計算値が低い場合には炉内側に向かって微小量厚さ（１０ｍｍ）を更に生成させ、更に各層の存在限界温度と同等の温度の位置を探索し該当する温度がある場合、該位置から低温側を該層の物性に置換した後、１０分間の非定常伝熱解析を行い、炉内側最内表面の位置７（流れの速度がゼロの溶融銑鉄の層の炉内側表面）の温度の計算値が、存在限界温度１３００°Ｃに等しいかそれ以下になる時刻まで１０分当たり１０ｍｍづつの生成を繰り返し、計算を進める。
【００２８】
このようにして得られた図８の９ａにおける温度Ｔａの計算結果は、図２の本発明による計算結果を示す破線の時刻ｔ₂からｔ₃までで示す。また、各層の状態の計算結果、すなわち図２の時刻ｔ₃における各層の残存状態は図１１に示す。
【００２９】
【発明の効果】
本発明により、炉底温度が過去の履歴の中で最高温度に達しない場合、および実測値が時間に依存して変化する場合にも、炉底耐火物の浸食状況、及び炉底耐火物内面に付着している内容物の形成の状況を把握することができるため、本発明は、高炉の操業管理ならびに炉底耐火物寿命診断に有効である。
【図面の簡単な説明】
【図１】高炉炉底の縦断面を模式的に示す断面図である。
【図２】図１に示す高炉健全耐火物２の、温度センサ−９ａの位置での温度実測データの時間変化とそれに対応する本発明の計算結果を示すタイムチャ−トである。
【図３】定常計算による厚さ推測領域と計算温度との関係を示すグラフであり、横方向は高炉の半径方向位置、縦方向は温度レベルである。
【図４】実在の高炉の長期使用後の炉底解体調査観察結果を模式的に示す、縦断面図である。
【図５】本発明で用いる伝熱計算用一次元多層モデルでの高炉の半径方向の層分割を示す模式的な断面図であり、横方向が半径方向である。
【図６】図５と同様な模式的な断面図であるが、温度が上昇する過程における炉内側表面内容物の消滅を概念的に示す。
【図７】図５と同様な模式的な断面図であるが、温度が下降する過程における炉内側表面内容物の生成を概念的に示す。
【図８】図５と同様な模式的な断面図であるが、本発明の実施例における伝熱計算用一次元多層モデルでの層分割を示す。
【図９】図８と同様な模式的な断面図であるが、図２の時刻ｔ₁における各層の残存状態を示す。
【図１０】図８と同様な模式的な断面図であるが、図２の時刻ｔ₂における各層の残存状態を示す。
【図１１】図８と同様な模式的な断面図であるが、図２の時刻ｔ₃における各層の残存状態を示す。
【符号の説明】
１：鉄皮２：炉底耐火物の健全部分
３：炉底耐火物内面に付着する内容物４：耐火物の浸食部分
５：鉄皮表面
６：炉底耐火物の浸食後の健全部表面ライン
７：炉底耐火物内面に付着する内容物の炉内側最内表面ライン
８：高炉稼働開始初期の耐火物炉内側表面ライン
９：炉底に設置された温度センサー
１１：実際の炉内側最内表面の位置
１２：定常計算から求められる炉内側最内表面の位置
１３：流れの速度がゼロの溶融銑鉄の層
１４：固体と液体の共存している銑鉄の層
１５：凝固した銑鉄の層１６：健全な耐火物以外の耐火物
１７：炉底耐火物の健全部分１８：充填材
１９：鉄皮２０：消滅させる層
２１：消滅前の炉内側最内表面の位置
２２：消滅後の炉内側最内表面の位置
２３：生成させる層
２４：生成後の炉内側最内表面の位置
２５：生成前の炉内側最内表面の位置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of estimating the inside of a bottom of a blast furnace (hereinafter referred to as a blast furnace), and in particular, for blast furnace operation management and bottom refractory life diagnosis, erosion state of bottom refractory, and bottom refractory. The present invention relates to a method for grasping the state of formation of contents attached to the inner surface.
[0002]
[Prior art]
The state of the bottom of a general blast furnace is schematically shown in FIG. The remaining thickness of the healthy part 2 after erosion of the refractory in the blast furnace (erosion part 4) and the thickness of the solidified layer 3 of the contents adhering to the inner surface of the refractory are shown in FIG. The conventional method of estimating by heat transfer calculation using the actual measurement values measured by the installed temperature sensors 9, 9a, 9b, 9c and the like is specifically as follows. That is, the erosion shape 6 of the furnace bottom refractory is obtained from the value reached to the maximum temperature among the actual values measured by the temperature sensor installed in the refractory and the temperature of the surface 5 of the iron skin 1 or the heat transfer conditions on the iron skin surface. Usually, the temperature of this portion is 1150 ° C., which is the freezing point temperature of the molten iron), and the remaining thickness is obtained.
[0003]
However, since such a conventional estimation method is one-dimensional, the estimated shape matches the fact that the erosion shape of the bottom refractory seen during the actual demolition investigation of the bottom is a curved complex shape. In many cases, there was a problem in the estimation accuracy of the remaining thickness of the healthy part 2 of the furnace bottom refractory.
[0004]
As a method to solve this, assuming that the bottom refractory erosion shape is a continuous line, two-dimensionally using the difference method or the finite element method to obtain sequentially, determine the erosion shape to reproduce the measured temperature, Estimating the remaining thickness of the bottom refractory is performed. For example, in the invention disclosed in Japanese Patent Publication No. 57-51445, the difference between the actually measured temperature and the estimated reference temperature that is the calculated value is used to correct the previously assumed erosion shape of the refractory, thereby Seeking erosion shape.
[0005]
In the invention disclosed in Japanese Examined Patent Publication No. 61-37328, the boundary element method and the mathematical programming method are combined to estimate the erosion shape of the furnace bottom refractory and the solidification shape of the contents in the furnace. In the invention disclosed in Japanese Patent Laid-Open No. 7-278632, the distribution state of the bottom refractory and the contents is optimized using a finite element method and a genetic algorithm which is one of optimization methods. Thus, the erosion shape of the furnace bottom refractory and the solidification shape of the contents in the furnace are estimated.
[0006]
[Problems to be solved by the invention]
However, as described above, the conventional methods for estimating the erosion shape of the furnace bottom refractory and the shape of the solidified layer of the contents in the furnace attached to the surface of the furnace bottom refractory have the following problems. is there.
[0007]
(A) First, in the estimation method according to the prior art, only the value at which the measured furnace bottom temperature reaches the maximum temperature is adopted, and in heat transfer calculation, the calculation is performed as a constant state independent of time. There is a problem. Actually, as shown in FIG. 2, the measured temperature of the furnace bottom (9a portion in FIG. 1) changes depending on the time, and erosion, which is the time when the remaining thickness of the refractory is most desired to be managed, progresses. When the remaining thickness becomes thinner, the temperature-dependent change of the measured value is further increased, and a refractory material having a high thermal conductivity is placed on the cylindrical side surface of the blast furnace shown in FIG. Due to the fact that it is often used, when it is calculated as a steady state as in the estimation method according to the prior art, the residual thickness of the bottom refractory and the solidified layer of the contents in the furnace attached to the refractory surface The thickness will be estimated incorrectly. That is, even when the actual temperature distribution in the blast furnace radial direction at a certain time, the actual thickness of the refractory, and the actual inner surface position 11 of the refractory are as shown in FIG. When the point, point a inside the refractory, and the same temperature as the point s' which is the inner surface of the refractory are estimated by steady calculation, the estimated temperature distribution is as shown by the broken line in FIG. Although the temperature S ″ is the same as S ′, the inner surface position of the thickness is different from the actual position 11 as 12.
[0008]
(B) Further, in the estimation method according to the prior art, in the heat transfer calculation, as shown in FIG. 1, in addition to the healthy portion 2 of the bottom refractory, the contents 3 in the furnace attached to the surface of the bottom refractory A physical property value is determined on the assumption that there is one kind of material, and generation and extinction thereof employs a method of continuously moving the line of the surface 7 of the contents in the furnace according to the temperature, which is also a problem. As shown in FIG. 4, based on the actual dismantling investigation of the blast furnace bottom, the furnace contents 3 are composed of two or more kinds of materials (3a, 3b), and the actually measured bottom temperature. 2 may rise rapidly from a stable state over a long period of time as shown in FIG. 2 and does not coincide with the heat transfer calculation result, resulting in the erosion shape 6 of the bottom refractory and the bottom refractory. The estimation of the thickness of the solidified layer of the in-furnace contents 3 attached to the surface is erroneous.
[0009]
Therefore, the present invention provides the remaining thickness of the refractory and the thickness of the contents layer even when the measured value of the furnace bottom temperature changes greatly depending on time or when the contents in the furnace are generated and disappeared. It is an object of the present invention to provide a method for estimating the blast furnace bottom state that can estimate the blast furnace.
[0010]
[Means for Solving the Problems]
The gist of the present invention is that a temperature sensor installed at the bottom of the blast furnace furnace is used to determine the wear time and remaining thickness of the refractory at the bottom of the blast furnace furnace and the generation / extinction time and residual thickness of the solidified layer of the content adhering to the inner surface of the refractory. Is a method for estimating the blast furnace bottom condition characterized by the following procedure.
[0011]
(A): In order to conduct heat transfer analysis of the blast furnace bottom structure, the bottom structure has the following five layers:
(A) a layer of sound refractory,
(B) a layer of refractory other than a healthy refractory,
(C) a solidified pig iron layer;
(D) a pig iron layer in which a solid and a liquid coexist;
(E) creating a model composed of layers of molten pig iron with zero flow velocity and assigning thickness and physical property values to each layer;
(B): The time-series data of the temperature of the bottom refractory measured by a plurality of temperature sensors installed in the bottom refractory is used as the actually measured bottom temperature.
(C): Unsteady heat transfer analysis depending on the elapsed time is performed on the model;
(D): Depending on the temperature of the analysis result, each layer of (A) is generated or extinguished. At that time, the limit temperature to be generated and the limit temperature to be extinguished are the same value or different values;
(E): Return to (C) and repeat (C) and (D) until the predetermined elapsed time to be calculated is reached, out of the temperature distribution obtained as the calculated value, the furnace bottom of the actually measured value of (B) The temperature value of the time series of the calculation result up to the predetermined elapsed time at the same position as the temperature is set as the calculated furnace bottom temperature;
(F): The furnace bottom temperature actually measured by (B), the minimum and maximum values of the furnace bottom temperature calculated by (E), the temperature rise rate and the temperature fall rate, and the temperature rise acceleration and temperature fall acceleration. Compare within a given time period;
(G): Return to (A), and change the thickness of the five types of layers again according to the difference in comparison between the actually measured furnace bottom temperature and the calculated furnace bottom temperature in (F) (C) ) Repeat the following procedure until the difference between the actually measured bottom temperature and the calculated bottom temperature in (F) is less than or equal to a predetermined value;
(H): The final state of the furnace bottom condition obtained by the thickness of each of the five types of layers (including zero thickness) in (A) when the repeated calculation in (G) is completed.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail. In the method for estimating the blast furnace bottom state according to the present invention, first, among the measured data of the furnace temperature, stable temperature data for 6 hours or more, that is, temperature data from time 0 to time t _{0 in} FIG. 5 is used to obtain the thickness of each

layer

13, 14, 15, and 16 of the contents attached to the inner surface of the furnace refractory and the inner surface of the furnace refractory in the model of the furnace bottom structure shown in FIG. The result is set as the initial state of the subsequent unsteady calculation.
[0013]
That is, using the actual measurement data of FIG. 2 measured by the temperature sensor 9 at the position of Ta in FIG. 5 and the temperature T1 of the outer surface of the iron shell in FIG. Is obtained, and physical property values of a multilayer model for heat transfer calculation of the furnace bottom structure shown in FIG. 5 are given, steady heat transfer calculation is performed, and the thickness of each layer is determined.
[0014]
Next, in the process of increasing the temperature as shown in the example from the time t ₀ to t ₂ of the measured data of the furnace bottom temperature shown in FIG. 2, that is, the contents attached to the furnace inner surface of the refractory or the sound Using the temperature data of the process including the refractory and disappearing, the heat transfer coefficient of the inner surface 7 of the molten pig iron layer 13, which is the innermost content layer inside the furnace, and whose flow velocity is zero Alternatively, the start of temperature rise of the heat source in the furnace is set as an initial condition, the previously obtained steady state is set as the initial state, and sequential calculation with respect to time, that is, time history transient response unsteady heat transfer analysis is started.
[0015]
Subsequently, the temperature of the surface of each layer of the sound refractory and attached contents, that is, the temperature at the position of Tx3, Tx2, Tx1, Tm, and Tc in FIG. If a position corresponding to a predetermined existence limit temperature is detected and the surface temperature of each layer is higher than the existence limit temperature of the layer, as shown in FIG. And the layer 20 corresponding to the thickness up to the depth 22 of the existence temperature of the layer is deleted or reduced, and the calculation proceeds at the next time.
[0016]
Thereafter, the same is repeated, and the surface of any layer is equivalent to the existence limit temperature of the layer, or the maximum value of the measured data is compared while comparing the calculation results at the same position as the measured data shown in FIG. Repeat the calculation until. The result can indicate the remaining thickness of the healthy part of the furnace bottom refractory at that time, or the residual thickness if the contents attached to the furnace inner surface of the refractory healthy part exist. .
[0017]
Subsequently, as shown in the example of t ₃ from the time t ₂ of the measured data of hearth temperatures shown in FIG. 2, process temperature is lowered, i.e., will be generated by the contents to the furnace inner surface of the refractory Using the temperature data of the process, the heat transfer coefficient on the inner surface side of the molten pig iron layer where the flow rate is zero, which is the innermost content layer inside the furnace, or the start of the temperature drop of the heat source in the furnace As an initial condition, sequential calculation with respect to time, that is, time history transient response unsteady heat transfer analysis is started.
[0018]
Subsequently, refer to the temperature of the innermost surface inside the furnace one by one along the time to calculate, and compare it with the limit temperature of each layer of the contents to be adhered, which are predetermined as physical properties, and the surface of a healthy refractory In the case where the temperature of the innermost inner surface of the contents is lower than the existence limit temperature of each layer of the contents to be deposited, the existence limit temperature closest to the calculated value is obtained as shown in FIG. The content layer 23 is formed with a fine thickness on the surface of the sound refractory or the innermost surface 25 inside the content furnace, and at the same time, the position of the existence limit temperature of each layer predetermined as the physical property value is referred to. Then, the thickness from the position to the position 24 of the existence limit temperature of the next layer on the low temperature side is replaced with the physical property value of the layer, and the calculation proceeds at the next time.
[0019]
Thereafter, in the same manner, the surface of any layer becomes equal to the existence limit temperature of the layer, or the maximum value t _{2 of the} measured data is compared while comparing the calculation results at the same position as the measured data shown in FIG. Repeat until it is equal to The result indicates the remaining thickness of the healthy part of the furnace bottom refractory at the time, or the remaining thickness if the contents attached to the furnace inner surface of the refractory healthy part exist. Become.
[0020]
【Example】
The method for estimating the blast furnace bottom state of the present invention was applied to a portion of the large blast furnace having an internal volume of 5000 m ^{3 in} which the thermometer 9a of the bottom of the blast furnace in FIG. The actual measurement data used for the analysis is a measurement result of a certain period at a position corresponding to 9a in FIG. 1, and is shown by a solid line in FIG. The multilayer model of heat transfer analysis corresponding to FIG. 5 gives physical properties to each layer as shown in FIG. 8 and Table 1, and the surface temperature of the outermost wall 19 (FIG. 8) uses an actually measured value of 30 ° C. It was. In FIG. 8, the position corresponding to the measurement position of the actual measurement data in FIG. 2 is the position 9a in the calculation model of FIG. 8, and the temperature is Ta as the calculation result. The finite element method was used as the calculation method.
[0021]
[Table 1]

[0022]
First, steady temperature analysis is performed using the Ta value from time 0 to t _0, which is the initial stable period of the measured data in FIG. 2, and the physical property values of each layer shown in FIG. 8 and Table 1, and each layer in FIG. Determine the unknown thickness. That is, the heat transfer coefficient α between the heat source and the surface of the innermost contents inside the furnace α = 38 kcal / m ² / hr / ° C., the thickness Lc = 750 mm of the healthy part of the furnace bottom refractory, and other than the sound refractory Refractory thickness Lm = 840mm, solidified pig iron layer thickness Lx1 = 100mm, solid and liquid pig iron layer thickness Lx2 = 98mm, zero flow velocity of molten pig iron layer The thickness Lx3 = 602 mm is determined.
[0023]
Subsequently, the temperature rise process of the actually measured data in FIG. 2, that is, the time t ₀ to t ₂ is analyzed. As an initial condition from time t ₀ to t ₂ , the heat transfer coefficient between the heat source and the surface of the innermost contents inside the furnace is changed from α = 38 kcal / m ² / hr / ° C to 115 kcal / m ² / hr / ° C. The time history transient response unsteady heat transfer analysis is started. The time increment in the time history transient response calculation was 10 minutes.
[0024]
Subsequently, the temperature of the inner surface of each layer shown in FIG. 8, that is, the position 7 of the innermost surface of the inner surface of the furnace, that is, the flow rate of the molten pig iron layer 13 whose flow velocity is zero, every 10 minutes in the calculation time step. Surface temperature Tx3, surface temperature Tx2 of pig iron layer 14 where solid and liquid coexist, surface temperature Tx1 of solidified pig iron layer 15, surface temperature Tm of refractory layer 16 other than healthy refractory, And the temperature Tc at the position of the surface 6 of the healthy part of the refractory, the respective existence limit temperatures, that is, Tx3 = 1300 ° C, Tx2 = 1180 ° C, Tx1 = 1150 ° C, Tm = 1300 ° C, and When Tc = 1180 ° C, the calculated value is high, a minute amount thickness (10 mm) is deleted from the innermost surface 7 of the content layer toward the outside of the furnace for 10 minutes. Conduct unsteady heat transfer analysis The calculation is advanced by repeating the deletion of 10 mm per 10 minutes until the time when the calculated value of the temperature of the inner surface is equal to or less than the temperature limit of each existence.
[0025]
The calculation result of the temperature Ta at 9a in FIG. 8 obtained in this way is shown by broken line times t ₀ to t ₂ showing the calculation result according to the present invention in FIG. FIG. 9 shows the calculation results of the state of each layer, that is, the remaining state of each layer at time t ₁ in FIG. 2, and FIG. 10 shows the remaining state of each layer at time t ₂ in FIG.
[0026]
Subsequently, the temperature decrease process of the actually measured data in FIG. 2, that is, the time t ₂ to t ₃ is analyzed. Since the initial condition from time t ₂ to t ₃ , that is, time t _{2 in} FIG. 2, was the start of the rest in actual operation, the temperature Th of the heat source in FIG. 8 was lowered from 1500 ° C. to 1470 ° C. Start the transient transient unsteady heat transfer analysis. The time increment in the time history transient response calculation was 10 minutes.
[0027]
Subsequently, a minute amount (10 mm) was attached as an initial condition to the innermost surface position 7 inside the furnace of the remaining layer shown in FIG. Then, the calculation result of the surface temperature Tx3 of the molten pig iron layer 13 where the flow speed is zero is searched and referred to, and when the calculated value is lower than the existence limit temperature 1300 ° C, the calculated value is small toward the inside of the furnace. When a quantity thickness (10 mm) is further generated, and a position of a temperature equivalent to the existence limit temperature of each layer is further searched and there is a corresponding temperature, the low temperature side from the position is replaced with the physical property of the layer for 10 minutes. The calculated value of the temperature at position 7 of the innermost inner surface of the furnace (the inner surface of the molten pig iron layer where the flow velocity is zero) is equal to the critical temperature of 1300 ° C. 10mm per 10 minutes until the following time Is repeated and calculation proceeds.
[0028]
Thus the calculation result of the temperature Ta in 9a of Figure 8 thus obtained is shown by the broken line in time t ₂ showing the calculation results of the present invention of FIG. 2 to t _3. FIG. 11 shows the calculation result of the state of each layer, that is, the remaining state of each layer at time t ₃ in FIG.
[0029]
【The invention's effect】
According to the present invention, even when the furnace bottom temperature does not reach the maximum temperature in the past history, and when the actual measurement value changes depending on time, the erosion situation of the furnace bottom refractory and the inner surface of the furnace refractory Therefore, the present invention is effective for blast furnace operation management and furnace bottom refractory life diagnosis.
[Brief description of the drawings]
FIG. 1 is a sectional view schematically showing a longitudinal section of a blast furnace bottom.
2 is a time chart showing the time change of temperature measurement data at the position of the temperature sensor 9a and the corresponding calculation result of the present invention for the blast furnace healthy refractory 2 shown in FIG.
FIG. 3 is a graph showing a relationship between a thickness estimation region by a steady calculation and a calculated temperature, in which the horizontal direction is a radial position of the blast furnace and the vertical direction is a temperature level.
FIG. 4 is a longitudinal sectional view schematically showing the result of a furnace bottom dismantling investigation observation after long-term use of an actual blast furnace.
FIG. 5 is a schematic cross-sectional view showing the radial division of the blast furnace in the one-dimensional multilayer model for heat transfer calculation used in the present invention, and the horizontal direction is the radial direction.
6 is a schematic cross-sectional view similar to FIG. 5, but conceptually showing the disappearance of the furnace inner surface contents in the process of increasing the temperature.
FIG. 7 is a schematic cross-sectional view similar to FIG. 5, but conceptually illustrating the generation of furnace interior surface contents in the process of decreasing temperature.
FIG. 8 is a schematic cross-sectional view similar to FIG. 5, but showing layer division in a one-dimensional multilayer model for heat transfer calculation in an embodiment of the present invention.
9 is a schematic cross-sectional view similar to FIG. 8, but shows the remaining state of each layer at time t ₁ in FIG.
10 is a schematic cross-sectional view similar to FIG. 8, but shows the remaining state of each layer at time t ₂ in FIG.
11 is a schematic cross-sectional view similar to FIG. 8, but shows the remaining state of each layer at time t ₃ in FIG.
[Explanation of symbols]
1: Iron skin 2: Healthy part of the furnace bottom refractory 3: Contents attached to the inner surface of the furnace bottom refractory 4: Erosion part of the refractory 5: Surface of the iron skin 6: Surface of the healthy part after erosion of the furnace bottom refractory Line 7: Furnace innermost surface of contents adhering to the inner surface of the furnace bottom refractory Line 8: Refractory furnace inner surface at the beginning of blast furnace operation line 9: Temperature sensor installed at the furnace bottom 11: Actual innermost furnace inner surface Inner surface position 12: Furnace innermost surface position 13 determined by steady state calculation: Molten pig iron layer 14 with zero flow velocity 14: Solid and liquid coexisting pig iron layer 15: Solidified pig iron layer 16: Refractory other than healthy refractory 17: Healthy part of furnace bottom refractory 18: Filler 19: Iron skin 20: Disappearing layer 21: Position of innermost inner surface of furnace before extinction 22: Furnace after extinction Inner innermost surface position 23: Generated layer 24: Furnace inner innermost surface position after generation 5: Position of production before the furnace inner innermost surface

Claims

Using the measured values of the temperature sensor installed at the bottom of the blast furnace furnace, the wear time and remaining thickness of the refractory at the bottom of the blast furnace furnace, the generation / extinction time of the solidified layer of the contents attached to the inner surface of the refractory, and the remaining thickness In the estimation method by heat transfer calculation, the estimation method of the blast furnace bottom condition characterized by the following procedure:
(A): In order to conduct heat transfer analysis of the blast furnace bottom structure, the bottom structure has the following five layers:
(A) a layer of sound refractory,
(B) a layer of refractory other than a healthy refractory,
(C) a solidified pig iron layer;
(D) a pig iron layer in which a solid and a liquid coexist;
(E) creating a model composed of layers of molten pig iron with zero flow velocity and assigning thickness and physical property values to each layer;
(B): The time-series data of the temperature of the bottom refractory measured by a plurality of temperature sensors installed in the bottom refractory is used as the actually measured bottom temperature.
(C): Unsteady heat transfer analysis depending on the elapsed time is performed on the model;
(D): Depending on the temperature of the analysis result, each layer of (A) is generated or extinguished. At that time, the limit temperature to be generated and the limit temperature to be extinguished are the same value or different values;
(E): Returning to (C), repeating (C) and (D) until reaching a predetermined elapsed time to be calculated, out of the temperature distribution obtained as a calculated value, the bottom of the measured value of (B) The temperature value of the time series of the calculation result up to the predetermined elapsed time at the same position as the temperature is set as the calculated furnace bottom temperature;
(F): The furnace bottom temperature actually measured by (B), the minimum and maximum values of the furnace bottom temperature calculated by (E), the temperature rise rate and the temperature fall rate, and the temperature rise acceleration and temperature fall acceleration. Compare within a given time period;
(G): Return to (A), and change the thickness of the five types of layers again according to the difference in comparison between the actually measured furnace bottom temperature and the calculated furnace bottom temperature in (F) (C) ) Repeat the following procedure until the difference between the actually measured bottom temperature and the calculated bottom temperature in (F) is less than or equal to a predetermined value;
(H): The final state of the furnace bottom situation in which the thicknesses including zero of each of the five types of layers in (A) when the repeated calculation in (G) is completed is obtained.