JP5262980B2 - Tundish delivery side molten steel temperature change prediction system and tundish delivery side molten steel temperature change prediction method - Google Patents
Tundish delivery side molten steel temperature change prediction system and tundish delivery side molten steel temperature change prediction method Download PDFInfo
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本発明はタンディッシュ出側溶鋼温度変化予測システム及びタンディッシュ出側溶鋼温度推移予測方法に関するものである。 The present invention relates to a tundish delivery side molten steel temperature change prediction system and a tundish delivery side molten steel temperature change prediction method.
鋼の連続鋳造は、転炉で精錬された溶鋼を鍋（溶鋼鍋）に受け取り、RHなどの二次精精錬処理を行った後、この鍋をタンディッシュの上方まで移動させてロングノズルを介してタンディッシュ内に注湯し、浸漬ノズルを介してその下方に設置された連続鋳造用鋳型に注湯して凝固させる方法で行われている。 In continuous casting of steel, molten steel refined in a converter is received in a pan (molten steel pan), and after secondary refining treatment such as RH, this pan is moved to above the tundish and passed through a long nozzle. In this method, the molten metal is poured into a tundish, and poured into a continuous casting mold installed below the immersion nozzle through an immersion nozzle to be solidified.
チャージ内のタンディッシュにおける溶鋼温度推移は、タンディッシュ内への溶鋼注湯開始直後から上昇し、所定量注湯後にピーク温度に達し、その後下降することが知られている。 It is known that the molten steel temperature transition in the tundish in the charge rises immediately after the start of pouring the molten steel into the tundish, reaches a peak temperature after pouring a predetermined amount, and then falls.
連続鋳造速度の設定に関し、凝固シェルの破壊による溶鋼流出トラブル（ブーレークアウト）を防ぎつつ、生産性を確保するために、タンディッシュ出側溶鋼温度変化を予測して、ピーク温度前後で低速設定する手法が一般的に採用されている。該ピーク温度は、溶鋼鍋からタンディッシュ内に注湯される溶鋼温度によって変動する。また、タンディッシュ内に注湯される溶鋼温度は、二次精錬最終温度や、溶鋼鍋の特性等により変動する。したがって、溶鋼鍋からタンディッシュ内へ連続して複数回行われる溶鋼チャージ毎に該ピーク温度は変動する。 Regarding the setting of continuous casting speed, in order to prevent the molten steel spill trouble (brokeout) due to the fracture of the solidified shell and to ensure the productivity, the temperature change of the tundish delivery side molten steel is predicted, and the low speed is set around the peak temperature. The technique to do is generally adopted. The peak temperature varies depending on the molten steel temperature poured from the molten steel pan into the tundish. Moreover, the molten steel temperature poured into the tundish varies depending on the final secondary refining temperature, the characteristics of the molten steel pan, and the like. Therefore, the peak temperature fluctuates for each molten steel charge that is continuously performed a plurality of times from the molten steel pan into the tundish.
したがって、ブレークアウトを防ぎつつ、生産性を確保するためには、各チャージ毎に、タンディッシュ出側溶鋼推移を実測温度値と比較して±１℃レベルで予測し、当該予測温度における許容最大鋳造速度で鋳造を行うことが好ましい。しかし、タンディッシュ出側溶鋼温度変化を正確に予測することは困難である。そこで、従来は、ブレークアウト防止の観点から、予測されるタンディッシュ出側溶鋼温度変化のピーク温度前後に更に幅を持たせた範囲で、許容最大鋳造速度よりも低速で鋳造するように鋳造速度設定をしており、生産性の観点から好ましくないという問題があった。 Therefore, in order to ensure productivity while preventing breakout, for each charge, the transition of the tundish delivery side molten steel is predicted at a ± 1 ° C level compared to the measured temperature value, and the allowable maximum at the predicted temperature is predicted. It is preferable to perform casting at a casting speed. However, it is difficult to accurately predict the temperature change of the tundish delivery side molten steel. Therefore, conventionally, from the viewpoint of preventing breakout, the casting speed is set so that casting is performed at a speed lower than the maximum allowable casting speed within a range where the width further increases around the peak temperature of the predicted tundish delivery side molten steel temperature change. There was a problem that it was not preferable from the viewpoint of productivity.
タンディッシュ内溶鋼温度変化を予測する技術に関し、例えば、特許文献１には、(a) タンディッシュ寸法、(b) 耐火物の要素分割データ、(c) 形態係数、(d) 耐火物物性値、(e) 耐火物初期温度、(f) タンディッシュ使用サイクル、及び(g) 鋳造時における溶鋼鍋内溶鋼温度を入力データとして入力し、耐火物やスラグと溶鋼の熱授受を計算して温度を推定する技術が開示されている。ここで、前記(g) 鋳造時における溶鋼鍋内溶鋼温度は、(a) 溶鋼鍋寸法、(b) 耐火物の要素分割データ（具体的には耐火物の厚さ方向における内壁表面，中間位置及び外壁表面の３点について温度を計算することにより耐火物の使用履歴とする）、(c) 形態係数（具体的には、ある特定の面から輻射される熱量のうち、別の面に到達する熱量の割合）、(d) 耐火物物性値（具体的には熱伝導率，膨張率）、(e) 耐火物初期温度（具体的には表面温度）、及び(f) 溶鋼鍋使用サイクルを入力データとして、伝熱計算により導かれている。 For example, Patent Document 1 discloses (a) tundish dimensions, (b) element division data of refractory, (c) form factor, and (d) refractory property values. , (E) Refractory initial temperature, (f) Tundish use cycle, and (g) Molten steel temperature in the ladle at the time of casting are input as input data, and the heat transfer between the refractory and slag and molten steel is calculated. A technique for estimating the above is disclosed. Here, (g) molten steel temperature in the molten steel ladle at the time of casting is (a) molten steel ladle size, (b) element division data of refractory (specifically, inner wall surface in the thickness direction of refractory, intermediate position) And refractory usage history by calculating the temperature at three points on the outer wall surface), (c) the shape factor (specifically, reaching the other surface of the amount of heat radiated from a certain surface) Ratio of heat to be generated), (d) refractory property values (specifically, thermal conductivity, expansion coefficient), (e) refractory initial temperature (specifically, surface temperature), and (f) molten steel pan use cycle Is input by the heat transfer calculation.
実際の取鍋内溶鋼には、二次精錬終了からタンディッシュへの注入開始までの間に鍋内の溶鋼に熱対流が発生し、鍋内上層部の溶鋼温度が高く、下層部は低くなる鍋内偏熱が発生しているが、特許文献１の上記モデルでは、当該偏熱の要素は考慮していない。このため、特許文献１の上記モデルによるタンディッシュ内溶鋼温度変化の予測精度は、実測温度値と比較して±５℃レベルに留まり、当該予測値を基に、許容最大鋳造速度を設定することは困難であるという問題があった。 In actual ladle molten steel, heat convection occurs in the molten steel in the pan between the end of secondary refining and the start of pouring into the tundish, the molten steel temperature in the upper layer in the pan is high, and the lower layer is low In the pan, heat is generated in the pan, but the above model of Patent Document 1 does not consider the element of the heat. For this reason, the prediction accuracy of the molten steel temperature change in the tundish by the above model of Patent Document 1 remains at ± 5 ° C. level as compared with the actually measured temperature value, and the allowable maximum casting speed is set based on the predicted value. Had the problem of being difficult.
本発明の目的は、前記問題を解決し、ブレークアウトを防ぎつつ高い生産性の実現を可能とする、高精度のタンディッシュ出側溶鋼温度変化予測システム、および該システムを用いたタンディッシュ出側溶鋼温度推移予測方法と連続鋳造方法を提供することである。 An object of the present invention is to provide a highly accurate tundish delivery side molten steel temperature change prediction system that solves the above-described problems and enables high productivity while preventing breakout, and a tundish delivery side using the system. It is to provide a molten steel temperature transition prediction method and a continuous casting method.
上記課題を解決するためになされた本発明のタンディッシュ出側溶鋼温度変化予測システムは、溶鋼鍋からタンディッシュ内に注湯される注入溶鋼温度推移モデルと、タンディッシュ内からモールドに注湯される出側溶鋼温度推移モデルとを、記憶する記憶手段と、タンディッシュ出側溶鋼温度を連続測定する出側溶鋼温度連続実測手段と、タンディッシュ出側溶鋼温度推移予測データを作成する情報処理手段を有する出側溶鋼温度変化予測システムであって、該注入溶鋼温度推移モデルは、注入開始温度から一定の勾配で昇温後、一定の勾配で降温する温度推移モデルであって、該出側溶鋼温度推移モデルは、溶鋼鍋からタンディッシュ内への溶鋼チャージが複数回行われる連続鋳造過程で、タンディッシュ内に残存する前チャージの溶鋼と、現チャージの溶鋼との混ざりを考慮しながら、現チャージの溶鋼注入開始後Δｔにおける総エンタルピーを計算する温度推移モデルであって、情報処理手段は、現チャージの溶鋼を重量比で５％〜４０％注入時点で、タンディッシュ出側溶鋼温度連続実測手段が測定したタンディッシュ出側溶鋼連続測定温度推移と、タンディッシュ出側溶鋼温度推移モデルによる温度推移とを対比して、両者が一致するようにタンディッシュ出側溶鋼温度推移モデルの設定値を補正し、更に、出側溶鋼温度推移モデルをリバース方向に適用して現チャージの溶鋼注入開始時のタンディッシュ注入溶鋼温度を決定した後、該決定温度をタンディッシュ注入溶鋼温度推移モデルに適用してタンディッシュ注入溶鋼温度推移データを作成し、該タンディッシュ注入溶鋼温度推移データをタンディッシュ出側溶鋼温度推移モデルに適用してタンディッシュ出側溶鋼温度推移予測データを作成することを特徴とするものである。 The tundish delivery side molten steel temperature change prediction system of the present invention, which has been made to solve the above problems, is a molten steel temperature transition model poured into the tundish from the molten steel pan, and poured into the mold from the tundish. Storage means for storing the molten steel temperature transition model, continuous molten steel temperature measurement means for continuously measuring the tundish molten steel temperature, and information processing means for creating tundish molten steel temperature prediction data A molten steel temperature transition prediction system having a temperature transition model in which the molten molten steel temperature transition model is a temperature transition model in which the temperature is increased at a constant gradient from the injection start temperature and then decreased at a constant gradient. The temperature transition model is a continuous casting process in which molten steel is charged multiple times from the molten steel pan into the tundish, and the precharged molten steel remaining in the tundish. The temperature transition model for calculating the total enthalpy at Δt after the start of molten steel injection of the current charge while taking into account the mixing with the molten steel of the current charge, wherein the information processing means At the time of 40% injection, the continuous measurement temperature transition of the tundish delivery side molten steel measured by the tundish delivery side molten steel continuous measurement means and the temperature transition by the tundish delivery side molten steel temperature transition model are compared, and both agree. After correcting the set value of the molten steel temperature transition model of the tundish, and further determining the tundish molten steel temperature at the start of the molten steel injection of the current charge by applying the molten steel temperature transition model in the reverse direction, The determined temperature is applied to the tundish injection molten steel temperature transition model to create tundish injection molten steel temperature transition data, and the tundish injection The molten steel temperature transition data is applied to the tundish outlet side molten steel temperature transition model to create tundish outlet side molten steel temperature transition prediction data.
請求項２記載の発明は、請求項１記載のタンディッシュ出側溶鋼温度変化予測システムにおいて、注入溶鋼温度推移モデルは、注入開始温度から注入開始後１０分間で５℃昇温後、一定の勾配で降温する温度推移モデルであって、該出側溶鋼温度推移モデルは、タンディッシュ内を架空の多槽構造とする多槽完全混合モデルを適用し、現チャージの溶鋼注入開始後Δｔにおける各槽への溶鋼流出入量および各槽内耐火物への抜熱量を考慮して計算する温度推移モデルであることを特徴とするものである。 The invention according to claim 2 is the tundish delivery side molten steel temperature change prediction system according to claim 1, wherein the molten steel temperature transition model is a constant gradient after a temperature increase of 5 ° C. within 10 minutes from the injection start temperature. A temperature transition model for lowering the temperature at the outlet side, wherein the outlet side molten steel temperature transition model applies a multi-tank complete mixing model in which the inside of the tundish is a fictitious multi-tank structure, and each tank at Δt after the start of molten steel injection of the current charge It is a temperature transition model that is calculated in consideration of the amount of molten steel flowing into and out of the tank and the amount of heat removed from the refractories in each tank.
請求項３記載のタンディッシュ出側溶鋼温度推移予測方法は、請求項１または２記載のタンディッシュ出側溶鋼温度変化予測システムを用いてタンディッシュ出側温度推移を予測することを特徴とするものである。 The tundish delivery side molten steel temperature transition prediction method according to claim 3 is characterized by predicting the tundish delivery side temperature transition using the tundish delivery side molten steel temperature change prediction system according to claim 1 or 2. It is.
本発明に係るタンディッシュ出側溶鋼温度変化予測システムは、溶鋼鍋からタンディッシュ内に注湯される注入溶鋼温度推移モデルと、タンディッシュ内からモールドに注湯される出側溶鋼温度推移モデルを用いて、現チャージの溶鋼を重量比で５％〜４０％注入時点で、現時点以降のタンディッシュ出側溶鋼温度推移予測データを作成する。ここで、該注入溶鋼温度推移モデルは、注入開始温度から一定の勾配で昇温後、一定の勾配で降温する温度推移モデルとし、該出側溶鋼温度推移モデルは、溶鋼鍋からタンディッシュ内への溶鋼チャージが複数回行われる連続鋳造過程で、タンディッシュ内に残存する前チャージの溶鋼と、現チャージの溶鋼との混ざりを考慮しながら、現チャージの溶鋼注入開始後Δｔにおける総エンタルピーを計算する温度推移モデルとした。これにより、タンディッシュ出側溶鋼推移を、実測温度値と比較して±１℃レベルで高精度に予測可能とした。 The tundish delivery side molten steel temperature change prediction system according to the present invention includes a molten steel temperature transition model poured into the tundish from the molten steel pan, and a delivery side molten steel temperature transition model poured into the mold from the tundish. Using the current charge of molten steel at the time of 5% to 40% injection by weight, tundish delivery side molten steel temperature transition prediction data after the current time is created. Here, the molten steel temperature transition model is a temperature transition model in which the temperature is increased at a constant gradient from the injection start temperature, and then the temperature is decreased at a constant gradient. The outlet molten steel temperature transition model is from the molten steel pan to the tundish. Calculate the total enthalpy at Δt after the start of the molten steel injection of the current charge, taking into account the mixing of the molten steel of the previous charge remaining in the tundish with the molten steel of the current charge in the continuous casting process where the molten steel charge is performed multiple times A temperature transition model was used. As a result, the transition of molten steel on the tundish delivery side can be predicted with high accuracy at a level of ± 1 ° C. compared with the actually measured temperature value.
請求項３記載のンディッシュ出側溶鋼温度推移予測方法によれば、上記タンディッシュ出側溶鋼温度変化予測システムを適用することにより、ブレークアウトを防ぎつつ生産性の向上を図ることが可能となる。 According to the nudish delivery side molten steel temperature transition prediction method according to claim 3, by applying the tundish delivery side molten steel temperature change prediction system, it becomes possible to improve productivity while preventing breakout. .
以下に本発明の好ましい実施形態を示す。 Preferred embodiments of the present invention are shown below.
図１には、本発明のタンディッシュ出側溶鋼温度変化予測システムの概略説明図を示している。本発明のタンディッシュ内溶鋼温度変化予測システムは、鋼の連続鋳造工程において、溶鋼鍋２からロングノズルを介してタンディッシュ１内に注湯された溶鋼が、タンディッシュ１内からモールドに注湯される際の、タンディッシュ出側溶鋼温度推移を高精度に予測し、該出側溶鋼温度（Tout）によって最大許容速度が規定される鋳造速度を最適に調整可能とするものである。 In FIG. 1, the schematic explanatory drawing of the tundish delivery side molten steel temperature change prediction system of this invention is shown. In the tundish molten steel temperature change prediction system according to the present invention, in the continuous casting process of steel, molten steel poured from the molten steel pan 2 into the tundish 1 through the long nozzle is poured into the mold from the tundish 1. The tundish delivery side molten steel temperature transition at this time is predicted with high accuracy, and the casting speed at which the maximum allowable speed is defined by the delivery side molten steel temperature (T out ) can be adjusted optimally.
本発明のタンディッシュ出側溶鋼温度変化予測システムは、溶鋼鍋からタンディッシュ内に注湯される溶鋼の温度推移モデル（以下、注入溶鋼温度推移モデル３）と、タンディッシュ内からモールドに注湯される溶鋼の温度推移モデル（以下、出側溶鋼温度推移モデル４）とを、該モデル３、４を記憶する記憶手段５と、タンディッシュ出側溶鋼温度（Tout）を連続測定する出側溶鋼温度連続実測手段７と、タンディッシュ出側溶鋼温度推移予測データを作成する情報処理手段６から構成される。 The tundish delivery side molten steel temperature change prediction system of the present invention includes a temperature transition model of molten steel poured into a tundish from a molten steel pan (hereinafter referred to as an injection molten steel temperature transition model 3), and a molten metal poured into the mold from the tundish. The temperature transition model of the molten steel (hereinafter referred to as the outgoing side molten steel temperature transition model 4), the storage means 5 for storing the models 3 and 4, and the outgoing side for continuously measuring the tundish outgoing side molten steel temperature ( Tout ) It is comprised from the molten steel temperature continuous measurement means 7 and the information processing means 6 which produces tundish delivery side molten steel temperature transition prediction data.
（注入溶鋼温度推移モデル３）
溶鋼鍋２から注湯される溶鋼温度（Tin）の推移は、注入流量や鍋蓄熱量に関わらず、例えば図２に示す、注入溶鋼温度推移モデル３で表現される。該注入溶鋼温度推移モデル３は、「鍋内の溶鋼の平均温度」の経時変化を表わすグラフと、鍋内の偏熱程度を表す「鍋注入溶鋼温度−鍋内溶鋼平均温度」の経時変化を表わすグラフとを組み合わせて、簡易モデル化したものである。
(Injected molten steel temperature transition model 3)
The transition of the molten steel temperature (T in ) poured from the molten steel pan 2 is expressed by, for example, an injected molten steel temperature transition model 3 shown in FIG. 2 regardless of the injection flow rate and the pot heat storage amount. The pouring molten steel temperature transition model 3 is a graph showing the change with time of the “average temperature of molten steel in the pan” and the change with time of “pot pouring molten steel temperature—the average temperature of molten steel in the pan” indicating the degree of uneven heat in the pan. This is a simple model that combines the graph to represent.
鍋内では、耐火物近傍で冷却された溶鋼は密度が高くなるため耐火物表面近傍を底面側へ移動し、温度の高い溶鋼は鍋の中央部を上面側へ移動する対流が発生する。この熱対流の発生で、底面側の溶鋼温度は低く、上面にいく程溶鋼温度は高い状態となっている。このように、偏熱している鍋内の溶鋼平均温度は、鍋耐火物への抜熱により、一律に低下していく。したがって、前記の「鍋内の溶鋼の平均温度」の経時変化を表わすグラフは、一定の降温速度を示すグラフとなる。 In the pan, the molten steel cooled in the vicinity of the refractory has a high density, so that the vicinity of the surface of the refractory moves to the bottom surface side, and the molten steel having a high temperature generates convection that moves the center of the pan to the top surface side. Due to the occurrence of this thermal convection, the molten steel temperature on the bottom surface side is low, and the molten steel temperature is higher as it goes to the upper surface. Thus, the average molten steel temperature in the pan that is biased by heat is uniformly reduced by heat removal from the pan refractory. Therefore, the graph showing the change with time of the “average temperature of molten steel in the pan” is a graph showing a constant rate of temperature decrease.
また、注入が進み鍋内溶鋼の浴深が浅くなるに従って、鍋内の偏熱程度を表す「鍋注入溶鋼温度−鍋内溶鋼平均温度」の値は小さくなる。これは、溶深が浅くなるほど、熱対流が発生しにくくなるためである。 Further, as the pouring progresses and the bath depth of the molten steel in the pan becomes shallow, the value of “pot pouring molten steel temperature−average molten steel temperature in the pan” indicating the degree of uneven heat in the pan decreases. This is because thermal convection is less likely to occur as the melting depth becomes shallower.
本発明では、前記の「鍋注入溶鋼温度−鍋内溶鋼平均温度」の経時変化を表わすグラフと、「鍋内の溶鋼の平均温度」の経時変化を表わすグラフとを組み合わせて得た簡易モデルを、注入溶鋼温度推移モデル３としている。 In the present invention, a simple model obtained by combining the above-mentioned graph representing the time-dependent change of the “potted molten steel temperature—the average temperature of the molten steel in the pot” and the graph representing the time-dependent change of the “average temperature of the molten steel in the pot”. The molten steel temperature transition model 3 is used.
図２において、αは、二次精錬終了からＣＣ（連続鋳造）注入スタートまでの鍋内溶鋼の温度降下率を表している。βは、鍋内平均温度降下率を表している。 In FIG. 2, α represents the temperature drop rate of the molten steel in the pan from the end of secondary refining to the start of CC (continuous casting) injection. β represents the average temperature drop rate in the pan.
α（℃／ｍｉｎ）は、二次精錬終了時の温度測定の時刻(ｔＡ）と測定温度(ＴＡ）と後鍋スタートの時刻(ｔＢ）を実測し、更に、下記に詳述する出側溶鋼温度推移モデル４を用いてフィティンク゛させた温度(ＴＢ）を演算し、これらの値を下記（数１）式に適用して求められる。 α (° C./min) is a temperature measurement time (t A ) at the end of secondary refining (t A ), a measured temperature (T A ), and a time (t B ) at which the pan starts, and is described in detail below. The temperature (T B ) fitted using the outgoing side molten steel temperature transition model 4 is calculated, and these values are obtained by applying the following equation (Equation 1).
β（℃／ｍｉｎ）は、上記αの値を、下記（数２）式に適用して求められる。 β (° C./min) is obtained by applying the value of α to the following (Equation 2).
α、βは当該チャージの鍋耐火物の蓄熱状態でほぼ決まっているため、近い値となる。しかし、転炉受鋼からの経過時間は、αに対してβが長いため、耐火物の蓄熱が進み溶鋼の抜熱量が低下するため、βはαより小さくなる。 Since α and β are almost determined by the heat storage state of the pot refractory with the charge, they are close to each other. However, since β is longer than α in the elapsed time from converter steel, β is smaller than α because heat storage of the refractory progresses and the heat removal amount of the molten steel decreases.
図２には、注入溶鋼温度推移モデル３の一例として、注入開始温度から注入開始後１０分間で５℃昇温後、一定の勾配で降温する温度推移モデルを示している。該温度推移モデルは、熱流動解析により、耐火物の抜熱による鍋内溶鋼熱対流を考慮しつつ、鍋注入溶鋼温度を時系列的に算出して得られたモデルである。該モデルの立ち上がり係数（１０ｍｉｎで５℃）は、鍋の耐火物厚み、鍋形状（内径/深さ）、二次精錬終了からCC注入スタートまでの時間で変化するため、その工場に合った係数を見直すことが望ましい。 FIG. 2 shows, as an example of an injection molten steel temperature transition model 3, a temperature transition model in which the temperature is lowered at a constant gradient after a temperature increase of 5 ° C. within 10 minutes from the injection start temperature. The temperature transition model is a model obtained by time-sequentially calculating the temperature of the molten steel poured into the pan by taking into account the molten steel thermal convection due to heat removal from the refractory by heat flow analysis. The rise factor (5 ° C for 10 min) of the model varies depending on the refractory thickness of the pan, the pan shape (inner diameter / depth), and the time from the end of secondary refining to the start of CC injection. It is desirable to review.
（出側溶鋼温度推移モデル４）
図３には、出側溶鋼温度推移モデル４の説明図を示している。タンディッシュ１内からモールドに注湯される溶鋼温度（Tout）の推移を求める出側溶鋼温度推移モデル４は、溶鋼鍋からタンディッシュ内への溶鋼チャージが複数回行われる連続鋳造過程で、タンディッシュ内に残存する前チャージの溶鋼と、現チャージの溶鋼との混ざりを考慮しながら、現チャージの溶鋼注入開始後Δｔにおける総エンタルピーを計算するものである。
(Outside molten steel temperature transition model 4)
In FIG. 3, the explanatory view of the outgoing side molten steel temperature transition model 4 is shown. The outgoing side molten steel temperature transition model 4 for determining the transition of the molten steel temperature (T out ) poured into the mold from the tundish 1 is a continuous casting process in which the molten steel is charged from the molten steel pan into the tundish several times. The total enthalpy at Δt after the start of the molten steel injection of the current charge is calculated in consideration of the mixing of the molten steel of the previous charge remaining in the tundish and the molten steel of the current charge.
前記の総エンタルピー計算は、図３に示すように、タンディッシュ内を架空の多槽構造（V１、V２、V１´、V３、V４、V４´、V５、V５´）とする多槽完全混合モデルを適用し、現チャージの溶鋼注入開始後Δｔにおける各槽への溶鋼流出入量および各槽内耐火物への抜熱量を考慮した計算式によって行われる。 As shown in FIG. 3, the total enthalpy calculation described above is a multi-tank complete mixing model with a multi-tank structure (V1, V2, V1 ′, V3, V4, V4 ′, V5, V5 ′) in the tundish. Is applied by a calculation formula that takes into account the amount of molten steel flowing into and out of each tank and the amount of heat removed from each tank refractory at Δt after the start of molten steel injection of the current charge.
該多槽完全混合モデルでは、タンディシュ内を複数の仮想的な槽に分割している。槽内は完全混合モデルとし、それを層列につないだモデルとしている。このモデルの特徴は、簡易的な計算で、TD内の流動を考慮しつつ、溶鋼エンタルピーの移動をシミュレートできることである。注入された溶鋼が、既にタンディシュ内にある溶鋼と混ざり合いながらTD出側に移動していくことをシミュレートする。コンピューターを使った数値熱流動解析のほうが精度は高いが、計算負荷が高く、実際の鋳造時間よりも計算時間が長くなるため、今回の用途に使えない。 In the multi-tank complete mixing model, the inside of the tundish is divided into a plurality of virtual tanks. The inside of the tank is a completely mixed model, which is a model connected to a layer sequence. The feature of this model is that it is possible to simulate the movement of molten steel enthalpy while taking into account the flow in the TD with a simple calculation. Simulates that the injected molten steel moves to the TD exit side while mixing with the molten steel already in the tundish. The numerical heat flow analysis using a computer has higher accuracy, but the calculation load is higher and the calculation time is longer than the actual casting time, so it cannot be used for this application.
H型タンディシュへの鍋からの溶鋼注入形態としては、図３に示すように、１つの鍋から注入し注入時間の多くを占める定常注入、２つの鍋から同時に注入しているラップ注入、鍋注入がない非ラップ注入の３パターンがある。ラップ注入とは、鍋交換時、前鍋と後鍋を同時に注入する方法で、鍋交換時の溶鋼注入が途切れないためタンディシュの溶鋼重量変化を抑制でき、また各鍋の注入量を絞ることができるため前鍋スラグの流入やタンディシュスラグの巻き込みを減らすことができるため、鍋交換部の鋳片品位を向上できる。モールドでの引き抜き量が少ない場合、ラップ注入のための鍋の絞り注入を行うと詰まりを発生させる危険性があるため、前鍋注入終了後に後鍋を注入する非ラップ注入操業を行う。 As shown in Fig. 3, the molten steel is poured into the H-type tundish from one pot, which is a steady injection that occupies much of the injection time, a lap injection that is simultaneously injected from two pots, and a pot injection. There are three patterns of non-wrap injection without. Lap pouring is a method in which the front and rear pans are poured at the same time when the pan is replaced.The molten steel injection at the time of pan replacement is not interrupted, so the change in the molten steel weight of the tundish can be suppressed, and the amount of each pan can be reduced. Therefore, it is possible to reduce the inflow of the front pan slag and the entrainment of the tundish slag, so that the slab quality of the pan replacement part can be improved. When the amount of drawing in the mold is small, there is a risk of clogging when the pot is filled for wrap injection, so a non-wrap injection operation is performed in which the rear pot is injected after the completion of the front pot injection.
注入形態の違いで、槽列モデルの繋がり方が異なるが、図３の定常注入時を例にとり、モデル内容を詳細に説明している。図３の定常注入時の基礎式に示すように、現在と微小時間Δt経過後のi槽のエンタルピーバランスをとる。具体的には、現在のi槽内の総エンタルピーにΔtの間に流入する溶鋼エンタルピーを加え、流出する溶鋼エンタルピーを減じ、TD耐火物からの抜熱量を減じた値とΔt後のi槽の総エンタルピーが等しくなるように計算する。算出された総エンタルピーを溶鋼密度と溶鋼比熱で割り、溶鋼温度を算出する。各槽のエンタルピーの流入経路と流出経路数が異なるため、実際の式は、各槽により微妙に異なった形となる。V1、V1’、V4、V5、V4’、V5’槽はエンタルピーの流入経路が１つ、流出経路が１つであり、V2槽は流入経路が２つ、流出経路が２つであり、V3槽は流入経路が１つ、流出経路が２つであるため、それぞれのエンタルピーバランス式が異なる。 Although the connection method of the tank row model is different depending on the injection form, the contents of the model are described in detail by taking the steady injection in FIG. 3 as an example. As shown in the basic equation at the time of steady injection in FIG. 3, the enthalpy balance of the i tank after the lapse of the minute time Δt is obtained. Specifically, the molten steel enthalpy that flows during Δt is added to the total enthalpy in the current i tank, the molten steel enthalpy that flows out is reduced, the amount of heat removed from the TD refractory is reduced, and the i tank after Δt Calculate so that the total enthalpy is equal. The calculated total enthalpy is divided by the molten steel density and the specific heat of the molten steel to calculate the molten steel temperature. Since the number of enthalpy inflow paths and the number of outflow paths in each tank are different, the actual formula is slightly different depending on each tank. V1, V1 ', V4, V5, V4', V5 'tanks have one enthalpy inflow path and one outflow path, and V2 tanks have two inflow paths and two outflow paths. Since the tank has one inflow path and two outflow paths, each enthalpy balance formula is different.
各槽の抜熱量Hiは、TD耐火物の厚み方向の温度分布を非定常伝熱計算で解き算出した耐火物表面温度と溶鋼温度に溶鋼耐火物間の熱伝達係数をかけた値とした。タンディシュ耐火物の厚み方向の温度分布を非定常伝熱解析で解析しているため、鋳造の進行とともに蓄熱され抜熱量が低下するタンディシュへの抜熱量変化も精度よくシミュレートしている。
最終的に連続鋳造の速度を決めるV5、V5’槽の溶鋼温度推移を計算して表示する。
The heat removal amount Hi of each tank was a value obtained by multiplying the refractory surface temperature and the molten steel temperature obtained by solving the temperature distribution in the thickness direction of the TD refractory by unsteady heat transfer calculation and the heat transfer coefficient between the molten steel refractories. Since the temperature distribution in the thickness direction of the tundish refractory is analyzed by unsteady heat transfer analysis, the amount of heat removal to the tundish where heat is stored and the heat removal decreases as the casting progresses is accurately simulated.
Calculate and display the temperature change of the molten steel in the V5 and V5 'tanks, which ultimately determines the speed of continuous casting.
定常注入時に比較して、ラップ注入時、非ラップ注入時は鍋の注入パターンが異なるため、V1、V2、V1’槽のエンタルピーの流出入変化に対応するようにエンタルピーバランス式を変化させている。 The enthalpy balance formula is changed to correspond to the change in enthalpy inflow and outflow of V1, V2, and V1 'tanks, because the injection pattern of the pan is different at the time of lap injection and non-lap injection compared to the steady injection .
（情報処理手段６）
図４には、情報処理手段６の情報処理フロー説明図を示している。以下、情報処理手段６における情報処理ステップ(以下、ST)について説明する。
(Information processing means 6)
FIG. 4 shows an information processing flow explanatory diagram of the information processing means 6. Hereinafter, an information processing step (hereinafter referred to as ST) in the information processing means 6 will be described.
ST１では、現チャージの溶鋼を重量比で２５％（初期鍋内溶鋼重量を１００％とする）注入した時点で、前チャージに関するタンディッシュ出側溶鋼温度推移予測データと、出側溶鋼温度連続実測手段７で測定したタンディッシュ出側溶鋼温度連続実測データ（現チャージ溶鋼注入開始時から現時点まで）との対比を行い、温度差ΔTを算出する。ST２では、前記ΔTを用いて、出側溶鋼温度推移モデル４の補正を行う。ST３では、前記補正後の出側溶鋼温度推移モデル４をリバース方向に適用して、現チャージのB点（図４）における溶鋼温度（Tin）を決定する。ST４では、ST３で決定した現チャージのB点温度（Tin）を注入溶鋼温度推移モデル３に適用して、現チャージの注入溶鋼温度推移データを作成する。ST５では、ST４で作成した現チャージの注入溶鋼温度推移データを出側溶鋼温度推移モデル４に適用して、現チャージのタンディッシュ出側溶鋼温度推移予測データを作成する。 In ST1, when the molten steel of the current charge is injected by 25% by weight (the initial molten steel weight in the pan is 100%), the tundish outgoing side molten steel temperature transition prediction data related to the previous charge and the outgoing molten steel temperature continuous measurement The temperature difference ΔT is calculated by comparing with the tundish outgoing side molten steel temperature continuous measurement data (from the start of the current charge molten steel injection to the present time) measured by the means 7. In ST2, the outgoing molten steel temperature transition model 4 is corrected using the ΔT. In ST3, the corrected molten steel temperature transition model 4 is applied in the reverse direction to determine the molten steel temperature (T in ) at the B point (FIG. 4) of the current charge. In ST4, the B point temperature (T in ) of the current charge determined in ST3 is applied to the molten steel temperature transition model 3 to create the molten steel temperature transition data of the current charge. In ST5, the molten steel temperature transition data of the current charge created in ST4 is applied to the outgoing molten steel temperature transition model 4, and the tundish outgoing molten steel temperature transition prediction data of the current charge is created.
（モデル精度検証）
図５には、上記のタンディッシュ出側溶鋼温度推移予測データと実測データを対比したモデル精度検証データを示している。図５に示すように、本発明のタンディッシュ出側溶鋼温度変化予測システムによれば、タンディッシュ出側溶鋼推移を±１℃レベルで予測することができる。従って、発明のタンディッシュ出側溶鋼温度変化予測システムで作成したタンディッシュ出側溶鋼温度推移予測データを基に、当該予測温度における許容最大鋳造速度で鋳造を行うことにより、ブレークアウトを防ぎつつ高い生産性を確保できる。
(Model accuracy verification)
FIG. 5 shows model accuracy verification data comparing the tundish delivery side molten steel temperature transition prediction data and the actual measurement data. As shown in FIG. 5, according to the tundish delivery side molten steel temperature change prediction system of the present invention, the transition of the tundish delivery side molten steel can be predicted at the ± 1 ° C. level. Therefore, based on the tundish delivery side molten steel temperature transition prediction data created by the tundish delivery side molten steel temperature change prediction system of the invention, it is high while preventing breakout by casting at the maximum allowable casting speed at the predicted temperature. Productivity can be secured.
図６には、従来の鋳造速度設定パターンと、本発明による鋳造速度設定パターンを示している。従来は、タンディッシュ出側溶鋼温度変化を正確に予測することが困難であり、ブレークアウト防止の観点から、ピーク温度前後に更に幅を持たせて低速設定範囲を設定していたのに対し、本発明では、タンディッシュ出側溶鋼温度変化が±１℃レベルで予測可能なため、低速設定範囲をより限定的に設定することができる。本発明の適用によって、１２％の生産性向上が可能となった。 FIG. 6 shows a conventional casting speed setting pattern and a casting speed setting pattern according to the present invention. Previously, it was difficult to accurately predict the temperature change of the molten steel on the tundish delivery side, and from the viewpoint of preventing breakout, while setting a low speed setting range with more width around the peak temperature, In the present invention, since the temperature change of the tundish delivery side molten steel can be predicted at the ± 1 ° C. level, the low speed setting range can be set more limitedly. Application of the present invention has enabled a 12% productivity improvement.
１タンディッシュ
２溶鋼鍋
３注入溶鋼温度推移モデル
４出側溶鋼温度推移モデル
５記憶手段
６情報処理手段
７出側溶鋼温度連続実測手段
1 tundish 2 molten steel pan 3 molten steel temperature transition model 4 outgoing molten steel temperature transition model 5 storage means 6 information processing means 7 outgoing molten steel temperature continuous measurement means
Claims (3)
タンディッシュ出側溶鋼温度を連続測定する出側溶鋼温度連続実測手段と、
タンディッシュ出側溶鋼温度推移予測データを作成する情報処理手段を有する出側溶鋼温度変化予測システムであって、
該注入溶鋼温度推移モデルは、注入開始温度から一定の勾配で昇温後、一定の勾配で降温する温度推移モデルであって、
該出側溶鋼温度推移モデルは、溶鋼鍋からタンディッシュ内への溶鋼チャージが複数回行われる連続鋳造過程で、タンディッシュ内に残存する前チャージの溶鋼と、現チャージの溶鋼との混ざりを考慮しながら、現チャージの溶鋼注入開始後Δｔにおける総エンタルピーを計算する温度推移モデルであって、
情報処理手段は、現チャージの溶鋼を重量比で５％〜４０％注入時点で、前記出側溶鋼温度連続実測手段が測定したタンディッシュ出側溶鋼連続測定温度推移と、出側溶鋼温度推移モデルによる温度推移とを対比して、両者が一致するように出側溶鋼温度推移モデルの設定値を補正し、更に、出側溶鋼温度推移モデルをリバース方向に適用して現チャージの溶鋼注入開始時のタンディッシュ注入溶鋼温度を決定した後、該決定温度を注入溶鋼温度推移モデルに適用してタンディッシュ注入溶鋼温度推移データを作成し、該データを出側溶鋼温度推移モデルに適用してタンディッシュ出側溶鋼温度推移予測データを作成することを特徴とするタンディッシュ出側溶鋼温度変化予測システム。 Storage means for storing a molten steel temperature transition model poured into the tundish from the molten steel pan, and a delivery side molten steel temperature transition model poured into the mold from the tundish;
Continuously measuring means for the molten steel temperature on the outgoing side for continuously measuring the molten steel temperature on the tundish;
A delivery side temperature change prediction system having information processing means for creating tundish delivery side molten steel temperature transition prediction data,
The molten steel temperature transition model is a temperature transition model in which the temperature is increased at a constant gradient from the injection start temperature, and then the temperature is decreased at a constant gradient.
The molten steel temperature transition model takes into account the mixing of the precharged molten steel remaining in the tundish with the molten steel of the current charge in the continuous casting process in which molten steel is charged from the molten steel pan into the tundish several times. However, a temperature transition model for calculating the total enthalpy at Δt after the start of molten steel injection of the current charge,
Information processing means with a 5% to 40% injection point of the molten steel of the current charge at a weight ratio of said exit-side molten steel temperature continuously measured means tundish outlet side molten steel continuous measurement temperature transition as measured with, delivery side molten steel temperature transition model Compared with the temperature transition due to, correct the set value of the outgoing molten steel temperature transition model so that they match, and apply the outgoing molten steel temperature transition model in the reverse direction to start the molten steel injection of the current charge After determining the tundish injection molten steel temperature, the tundish injection molten steel temperature transition data is created by applying the determined temperature to the injected molten steel temperature transition model, and the data is applied to the outgoing molten steel temperature transition model. Tundish delivery side molten steel temperature change prediction system characterized by creating delivery side molten steel temperature change prediction data.
該出側溶鋼温度推移モデルは、タンディッシュ内を架空の多槽構造とする多槽完全混合モデルを適用し、現チャージの溶鋼注入開始後Δｔにおける各槽への溶鋼流出入量および各槽内耐火物への抜熱量を考慮して計算する温度推移モデルであることを特徴とする請求項１記載のタンディッシュ出側溶鋼温度変化予測システム。 The molten steel temperature transition model is a temperature transition model in which the temperature is lowered at a constant gradient after a temperature increase of 5 ° C. within 10 minutes from the injection start temperature,
The outlet side molten steel temperature transition model applies a multi-tank complete mixing model in which the inside of the tundish is an imaginary multi-tank structure, and the amount of molten steel flowing into and out of each tank at Δt after the start of molten steel injection of the current charge The tundish delivery side molten steel temperature change prediction system according to claim 1, wherein the temperature change model is calculated in consideration of a heat removal amount to the refractory.
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