JP7502627B2 - Method for determining the melting of pig iron, method for melting treatment of pig iron, and method for estimating the amount of melted pig iron - Google Patents
Method for determining the melting of pig iron, method for melting treatment of pig iron, and method for estimating the amount of melted pig iron Download PDFInfo
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Description
本発明は、銑鉄の溶解処理時における銑鉄の溶解判定方法、銑鉄の溶解処理方法、及び、銑鉄の溶解量推定方法に関するものである。 The present invention relates to a method for determining the dissolution of pig iron during the pig iron melting process, a pig iron melting process method, and a method for estimating the amount of dissolved pig iron.
高炉から出銑された溶銑は、例えば、トーピードカー等の移送容器に移して転炉に移動される。
ここで、溶銑を転炉に装入する前に、トーピードカー等の移送容器内において、排滓、脱珪、脱燐、脱硫などの転炉外精錬を行うことがある。これらの処理過程において、溶銑を出銑できずに長期滞留した場合に、トーピードカー等の溶銑が固化することがある。
The molten iron tapped from the blast furnace is transferred to a transfer vessel such as a torpedo car and then to a converter.
Before the molten iron is charged into the converter, it may be subjected to off-converter refining such as slag removal, desiliconization, dephosphorization, and desulfurization in a transfer vessel such as a torpedo car. If the molten iron is retained in the torpedo car for a long period of time during these treatments, the molten iron may solidify.
このため、トーピードカー等の移送容器においては、内部で固化した銑鉄を溶解して排出する銑鉄溶解処理作業を行う必要がある。
銑鉄溶解処理作業においては、トーピードカー等の移送容器内に燃料と酸素を含む助燃ガスを供給して燃焼させ、この燃焼熱によって固化した溶銑を溶解する。ここで、銑鉄が溶解した後に酸素を含む助燃ガスにより銑鉄が過酸化状態となり、酸化鉄を多量に含むスラグが発生すると、このスラグによって耐火物が劣化するおそれがある。このため、溶解した銑鉄を定期的に排出する必要がある。
For this reason, in transport vessels such as torpedo cars, it is necessary to carry out a pig iron melting process in which the solidified pig iron inside is melted and discharged.
In pig iron melting processing, fuel and oxygen-containing combustion supporting gas are supplied to a transport vessel such as a torpedo car and burned, and the solidified molten pig iron is melted by the heat of combustion. After the pig iron is melted, the oxygen-containing combustion supporting gas causes the pig iron to become overoxidized, and if slag containing a large amount of iron oxide is generated, there is a risk that the slag will deteriorate the refractories. For this reason, it is necessary to periodically discharge the molten pig iron.
移送容器内の銑鉄の溶解の有無の判定を目視で行う場合には、一時的に溶解処理を中断する必要がある。このため、熱効率が低下してしまい、効率良く銑鉄の溶解作業を行うことができなった。そこで、目視以外の方法で、銑鉄の溶解の有無を判断する手法が求められている。 When visually determining whether the pig iron in the transfer vessel has melted, the melting process must be temporarily interrupted. This reduces the thermal efficiency, making it impossible to efficiently melt the pig iron. Therefore, there is a need for a method other than visual inspection to determine whether the pig iron has melted.
ここで、特許文献１においては、排ガス中の一酸化炭素ＣＯと二酸化炭素ＣＯ２の割合の変化から、固体鉄源の溶解の有無を判定する方法が提案されている。
また、特許文献２においては、電気炉において、排ガス成分濃度が閾値未満となったときに、原料が溶解したと判断する方法が提案されている。
Here,
Moreover,
ところで、特許文献１，２においては、侵入空気の影響を考慮していないため、トーピードカー等の開放された空間での溶解の判定には適用できなかった。このため、従来は、トーピードカー等の移送容器内で固化した銑鉄の溶解の有無を判断する手法はなく、やはり、目視で確認する必要があった。
However,
本発明は、前述した状況に鑑みてなされたものであって、トーピードカー等の移送容器内で固化した銑鉄を溶解処理する際に、銑鉄の溶解の有無を精度良く判定することが可能な銑鉄の溶解判定方法、この銑鉄の溶解判定方法を利用した銑鉄の溶解処理方法及び銑鉄の溶解量推定方法を提供することを目的とする。 The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a method for determining the melting of pig iron that can accurately determine whether or not pig iron has melted when solidified pig iron is melted in a transport vessel such as a torpedo car, a method for melting pig iron using this method for determining the melting of pig iron, and a method for estimating the amount of melted pig iron.
上記の課題を解決するために、本発明者らが鋭意検討した結果、以下のような知見を得た。
排ガス温度、燃料流量、助燃ガス流量が定常であれば、燃焼量論計算上は排ガス成分系も定常となる。しかし、実際に、トーピードカー内で固化した銑鉄の溶解処理時の排ガス濃度を観察すると、排ガス温度、燃料流量、助燃ガス流量が定常状態でも、排ガスにおいて酸素濃度が低下し、二酸化炭素濃度が増大している状態が観察された。排ガスに混入する空気量の変動であれば、酸素および二酸化炭素は同じ傾向を示すと考えられるが、二種類のガスで異なる挙動を示したことから、銑鉄が溶解してスラグになる際に、飽和した炭素と酸素が結びつき二酸化炭素を発生させる反応が起きていると考えた。
In order to solve the above problems, the present inventors conducted extensive research and obtained the following findings.
If the exhaust gas temperature, fuel flow rate, and auxiliary gas flow rate are steady, the exhaust gas components will also be steady according to combustion theory calculations. However, when the exhaust gas concentrations were actually observed during the melting process of solidified pig iron inside a torpedo car, it was observed that the oxygen concentration in the exhaust gas decreased and the carbon dioxide concentration increased, even when the exhaust gas temperature, fuel flow rate, and auxiliary gas flow rate were steady. If it was a fluctuation in the amount of air mixed into the exhaust gas, oxygen and carbon dioxide would show the same trend, but because the two types of gases showed different behavior, it was thought that when the pig iron melted and became slag, a reaction occurred in which saturated carbon combined with oxygen to generate carbon dioxide.
本発明は、上述の知見に基づいてなされたものであって、本発明に係る銑鉄の溶解判定方法は、溶銑を移送する移送容器内において固化した銑鉄を溶解する際に、前記銑鉄の溶解の有無を判定する銑鉄の溶解判定方法であって、銑鉄溶解処理中に発生する排ガスをサンプリングして測定した実測二酸化炭素濃度と、排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から算出される排ガス中の理論二酸化炭素濃度と、を比較し、前記実測二酸化炭素濃度が前記理論二酸化炭素濃度よりも一定以上高くなった際に、前記銑鉄が溶解したと判断することを特徴としている。 The present invention has been made based on the above-mentioned findings, and the method for determining the dissolution of pig iron according to the present invention is a method for determining whether or not pig iron has melted when solidified pig iron is melted in a transfer vessel that transports molten iron, and is characterized in that an actual carbon dioxide concentration measured by sampling exhaust gas generated during the pig iron melting process is compared with a theoretical carbon dioxide concentration in the exhaust gas calculated from the exhaust gas temperature, the supporting gas flow rate, the fuel flow rate and the amount of invading air, and it is determined that the pig iron has melted when the actual carbon dioxide concentration is higher than the theoretical carbon dioxide concentration by a certain amount or more.
上述した銑鉄の溶解判定方法においては、銑鉄溶解処理中に発生する排ガス中の実測二酸化炭素濃度と、排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から算出される排ガス中の理論二酸化炭素濃度と、を比較し、前記実測二酸化炭素濃度が前記理論二酸化炭素濃度よりも一定以上高くなった際に、前記銑鉄が溶解したと判断する構成としているので、銑鉄の溶解の有無を判定することができる。
そして、前記理論二酸化炭素濃度を算出する際に、侵入空気量を考慮していることから、トーピードカー等の開放された空間における銑鉄の溶解の有無を精度良く判定することが可能となる。
In the above-mentioned method for determining whether pig iron has melted, the actual carbon dioxide concentration in the exhaust gas generated during the pig iron melting process is compared with the theoretical carbon dioxide concentration in the exhaust gas calculated from the exhaust gas temperature, the auxiliary gas flow rate, the fuel flow rate and the amount of invading air, and when the actual carbon dioxide concentration becomes higher than the theoretical carbon dioxide concentration by a certain amount or more, it is determined that the pig iron has melted, so that it is possible to determine whether the pig iron has melted or not.
Furthermore, since the amount of invading air is taken into consideration when calculating the theoretical carbon dioxide concentration, it becomes possible to accurately determine whether or not pig iron has melted in an open space such as a torpedo car.
あるいは、本発明に係る銑鉄の溶解判定方法は、溶銑を移送する移送容器内において固化した銑鉄を溶解する際に、前記銑鉄の溶解の有無を判定する銑鉄の溶解判定方法であって、銑鉄溶解処理中に発生する排ガスをサンプリングして測定した実測酸素濃度と、排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から算出される排ガス中の理論酸素濃度と、を比較し、前記実測酸素濃度が前記理論酸素濃度よりも一定以上低くなった際に、前記銑鉄が溶解したと判断することを特徴としている。 Alternatively, the method for determining the melting of pig iron according to the present invention is a method for determining whether or not pig iron has melted when solidified pig iron is melted in a transfer vessel that transports molten iron, and is characterized in that it compares an actual oxygen concentration measured by sampling exhaust gas generated during the pig iron melting process with a theoretical oxygen concentration in the exhaust gas calculated from the exhaust gas temperature, supporting gas flow rate, fuel flow rate and amount of invading air, and determines that the pig iron has melted when the actual oxygen concentration becomes lower than the theoretical oxygen concentration by a certain amount or more.
上述した銑鉄の溶解判定方法においては、銑鉄溶解処理中に発生する排ガス中の実測酸素濃度と、排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から算出される排ガス中の理論酸素濃度と、を比較し、前記実測酸素濃度が前記理論酸素濃度よりも一定以上低くなった際に、前記銑鉄が溶解したと判断する構成としているので、銑鉄の溶解の有無を判定することができる。
そして、前記理論酸素濃度を算出する際に、侵入空気量を考慮していることから、トーピードカー等の開放された空間における銑鉄の溶解の有無を精度良く判定することが可能となる。
In the above-mentioned method for determining whether pig iron has melted, the actual oxygen concentration in the exhaust gas generated during the pig iron melting process is compared with the theoretical oxygen concentration in the exhaust gas calculated from the exhaust gas temperature, the auxiliary gas flow rate, the fuel flow rate and the amount of invading air, and when the actual oxygen concentration becomes lower than the theoretical oxygen concentration by a certain amount or more, it is determined that the pig iron has melted, so that it is possible to determine whether the pig iron has melted or not.
Furthermore, since the amount of invading air is taken into consideration when calculating the theoretical oxygen concentration, it becomes possible to accurately determine whether or not pig iron has melted in an open space such as a torpedo car.
ここで、本発明に係る銑鉄の溶解判定方法においては、前記実測二酸化炭素濃度が前記理論二酸化炭素濃度よりも３ｖｏｌ％以上高くなった時点で、前記銑鉄が溶解したと判断する構成としてもよい。
この場合、前記実測二酸化炭素濃度と前記理論二酸化炭素濃度との間に明確な差異が生じており、的確に銑鉄の溶解の有無を判定することができる。
Here, in the method for determining the dissolution of pig iron according to the present invention, the pig iron may be determined to have melted when the measured carbon dioxide concentration is 3 vol % or more higher than the theoretical carbon dioxide concentration.
In this case, a clear difference occurs between the measured carbon dioxide concentration and the theoretical carbon dioxide concentration, and it is possible to accurately determine whether or not the pig iron has dissolved.
あるいは、本発明に係る銑鉄の溶解判定方法においては、前記実測酸素濃度が前記理論酸素濃度よりも３ｖｏｌ％以上低くなった時点で、前記銑鉄が溶解したと判断する構成とする構成としてもよい。
この場合、前記実測酸素濃度と前記理論酸素濃度との間に明確な差異が生じており、的確に銑鉄の溶解の有無を判定することができる。
Alternatively, in the method for determining the dissolution of pig iron according to the present invention, the pig iron may be determined to have melted when the measured oxygen concentration becomes lower than the theoretical oxygen concentration by 3 vol % or more.
In this case, a clear difference occurs between the measured oxygen concentration and the theoretical oxygen concentration, and it is possible to accurately determine whether or not the pig iron has dissolved.
本発明に係る銑鉄の溶解処理方法は、上述した銑鉄の溶解判定方法により、銑鉄が溶解したと判断された際に、前記助燃ガス流量及び前記燃料流量の一方又は両方を調整し、前記排ガス中の酸素濃度を低下させることを特徴としている。 The pig iron melting treatment method according to the present invention is characterized in that, when it is determined that the pig iron has melted by the pig iron melting determination method described above, one or both of the combustion supporting gas flow rate and the fuel flow rate are adjusted to reduce the oxygen concentration in the exhaust gas.
この構成の銑鉄の溶解処理方法によれば、銑鉄が溶解したと判断した時点で、前記排ガス中の酸素濃度を低下させているので、溶解した銑鉄（溶銑）と酸素の反応によってスラグが多量に生成することを抑制でき、耐火物の劣化を抑制することが可能となる。 According to this method for melting pig iron, the oxygen concentration in the exhaust gas is reduced when it is determined that the pig iron has melted, which makes it possible to prevent a large amount of slag from being produced by the reaction between the molten pig iron (molten pig iron) and oxygen, and to prevent deterioration of the refractory material.
本発明に係る銑鉄の溶解量推定方法は、上述した銑鉄の溶解判定方法により、銑鉄が溶解したと判断された時点からの経過時間に基づいて、前記銑鉄の溶解量を推定することを特徴としている。 The method for estimating the amount of dissolved pig iron according to the present invention is characterized in that it estimates the amount of dissolved pig iron based on the time elapsed from the point at which it is determined that the pig iron has melted using the above-mentioned pig iron melting determination method.
この構成の銑鉄の溶解量推定方法によれば、銑鉄が溶解したと判断された時点からの経過時間に基づいて前記銑鉄の溶解量を推定する構成とされているので、銑鉄の溶解量（溶銑量）を精度良く推定することが可能となる。 This method for estimating the amount of dissolved pig iron estimates the amount of dissolved pig iron based on the time elapsed since it was determined that the pig iron was melted, making it possible to accurately estimate the amount of dissolved pig iron (amount of molten pig iron).
上述のように、本発明によれば、トーピードカー等の移送容器内で固化した銑鉄を溶解処理する際に、銑鉄の溶解の有無を精度良く判定することが可能な銑鉄の溶解判定方法、この銑鉄の溶解判定方法を利用した銑鉄の溶解処理方法及び銑鉄の溶解量推定方法を提供することができる。 As described above, the present invention provides a pig iron melting determination method that can accurately determine whether pig iron has melted when solidified pig iron is melted in a transport vessel such as a torpedo car, a pig iron melting treatment method that utilizes this pig iron melting determination method, and a method for estimating the amount of melted pig iron.
以下に、本発明の実施形態である銑鉄の溶解判定方法、及び、この銑鉄の溶解判定方法を利用した銑鉄の溶解処理方法、銑鉄の溶解量推定方法について説明する。なお、本発明は、以下の実施形態に限定されるものではない。 The following describes a method for determining the dissolution of pig iron, which is an embodiment of the present invention, a method for dissolving pig iron using this method for determining the dissolution of pig iron, and a method for estimating the amount of dissolved pig iron. Note that the present invention is not limited to the following embodiment.
トーピードカー内で固化した銑鉄を溶解するために、燃焼バーナーから燃料（本実施形態ではプロパンガス）と助燃ガス（本実施形態では酸素ガス）をトーピードカー内に供給して燃焼させ、この燃焼熱によってトーピードカー内を加熱する。このとき、トーピードカーは密閉されていないため、外部から空気が侵入することになる。そして、燃焼によって生じる排ガスは煙突を通じて外部へと排出される。 To melt the solidified pig iron inside the torpedo car, fuel (propane gas in this embodiment) and combustion support gas (oxygen gas in this embodiment) are supplied from a combustion burner into the torpedo car and burned, and the inside of the torpedo car is heated by the heat of combustion. At this time, the torpedo car is not sealed, so air will enter from the outside. Exhaust gases produced by combustion are then discharged to the outside through the chimney.
本実施形態である銑鉄の溶解判定方法においては、煙突から排出される排ガスをサンプリングし、排ガス温度、二酸化炭素濃度、酸素濃度を、随時、測定する。
このとき、測定間隔は１秒以上６０秒以下の範囲内とすることが好ましい。また、測定値のばらつきの影響を抑えるために、例えば３個以上の測定データの平均値を算出し、実測二酸化炭素濃度、実測酸素濃度を得ることが好ましい。なお、測定データの平均値を算出する際の測定データ個数は４個以上であることがより好ましく、２４０個以上であることがさらに好ましい。本実施形態では、１８００個の測定データから平均値を算出している。
In the method for determining the melting of pig iron according to this embodiment, the exhaust gas discharged from the chimney is sampled, and the exhaust gas temperature, carbon dioxide concentration, and oxygen concentration are measured at any time.
At this time, the measurement interval is preferably within a range of 1 second to 60 seconds. In order to suppress the influence of the variation in the measured values, it is preferable to calculate the average value of, for example, three or more pieces of measurement data to obtain the actual measured carbon dioxide concentration and the actual measured oxygen concentration. It is more preferable that the number of pieces of measurement data when calculating the average value of the measurement data is four or more, and even more preferable that the number of pieces of measurement data is 240 or more. In this embodiment, the average value is calculated from 1800 pieces of measurement data.
そして、排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から排ガス中の理論二酸化炭素濃度、及び、理論酸素濃度を算出する。
ここで、侵入空気量ＱＡｉｒは、煙突効果と湿りガス量から、以下に示す（１）式、及び、（２）式によって算出される。
Then, the theoretical carbon dioxide concentration and the theoretical oxygen concentration in the exhaust gas are calculated from the exhaust gas temperature, the flow rate of the supporting gas, the flow rate of the fuel, and the amount of invading air.
Here, the amount of invading air Q Air is calculated from the stack effect and the amount of wet gas by the following formulas (1) and (2).
ここで、燃料と助燃ガスとの燃焼反応は、侵入空気量を考慮すると、以下の（３）式で表すことができる。なお、（３）式において、ａは酸素比である。 The combustion reaction between the fuel and the supporting gas can be expressed by the following formula (3), taking into account the amount of invading air. In formula (3), a is the oxygen ratio.
そして、排ガス中の理論二酸化濃度及び理論酸素濃度は、以下の式によって算出することができる。
理論二酸化炭素濃度＝排ガス二酸化炭素量／（乾き排ガス量＋侵入空気量）
理論酸素濃度＝（排ガス酸素量＋侵入空気量×0.21）／（乾き排ガス量＋侵入空気量）
The theoretical carbon dioxide concentration and theoretical oxygen concentration in the exhaust gas can be calculated by the following formulas.
Theoretical carbon dioxide concentration = exhaust gas carbon dioxide amount / (dry exhaust gas amount + invading air amount)
Theoretical oxygen concentration = (amount of oxygen in exhaust gas + amount of invading air x 0.21) / (amount of dry exhaust gas + amount of invading air)
そして、上述して得られた実測二酸化炭素濃度と理論二酸化炭素濃度、あるいは、実測酸素濃度と理論酸素濃度とを比較する。
ここで、トーピードカー内の銑鉄が溶解した際には、溶銑中の炭素と酸素が結びつき二酸化炭素を発生させる反応が生じる。これにより、図１及び図２に示すように、銑鉄が溶解した際には、実測二酸化炭素濃度が理論二酸化炭素濃度よりも高くなり、実測酸素濃度が理論酸素濃度よりも低くなる。
Then, the measured carbon dioxide concentration and the theoretical carbon dioxide concentration, or the measured oxygen concentration and the theoretical oxygen concentration, obtained as described above, are compared.
When the pig iron in the torpedo car melts, the carbon in the molten iron combines with oxygen to generate carbon dioxide, and as a result, the measured carbon dioxide concentration becomes higher than the theoretical carbon dioxide concentration, and the measured oxygen concentration becomes lower than the theoretical oxygen concentration, as shown in Figures 1 and 2.
そこで、実測二酸化炭素濃度が理論二酸化炭素濃度よりも一定以上高くなった際に、あるいは、実測酸素濃度が理論酸素濃度よりも一定以上低くなった際に、銑鉄が溶解したと判断することが可能となる。
なお、実測二酸化炭素濃度と理論二酸化炭素濃度との差が３ｖｏｌ％以上、あるいは、実測酸素濃度と理論酸素濃度との差が３ｖｏｌ％以上になった際に、銑鉄が溶解したと判断することが好ましい。
Therefore, when the measured carbon dioxide concentration becomes higher than the theoretical carbon dioxide concentration by a certain amount or more, or when the measured oxygen concentration becomes lower than the theoretical oxygen concentration by a certain amount or more, it is possible to determine that the pig iron has melted.
It is preferable to determine that the pig iron has melted when the difference between the measured carbon dioxide concentration and the theoretical carbon dioxide concentration is 3 vol.% or more, or when the difference between the measured oxygen concentration and the theoretical oxygen concentration is 3 vol.% or more.
ここで、本実施形態である銑鉄の溶解処理方法においては、上述した銑鉄の溶解判定方法によって銑鉄が溶解したと判断された際に、助燃ガス流量及び燃料流量の一方又は両方を調整し、排ガス中の酸素濃度を低下させる構成としている。
銑鉄が溶解した後に、酸素濃度が高いと、溶解した銑鉄（溶銑）と酸素とが反応してスラグが多量に生成し、耐火物が劣化することになる。これを防止するために、銑鉄が溶解したと判断された時点で、排ガス中の酸素濃度を低下させることが好ましい。
Here, in the pig iron melting treatment method of this embodiment, when it is determined that the pig iron has melted by the above-mentioned pig iron melting determination method, one or both of the auxiliary gas flow rate and the fuel flow rate are adjusted to reduce the oxygen concentration in the exhaust gas.
If the oxygen concentration is high after the pig iron is melted, the molten pig iron (hot metal) reacts with oxygen to produce a large amount of slag, which deteriorates the refractory. In order to prevent this, it is preferable to reduce the oxygen concentration in the exhaust gas when it is determined that the pig iron has melted.
また、本実施形態である銑鉄の溶解量推定方法においては、上述した銑鉄の溶解判定方法によって銑鉄が溶解したと判断された時点からの経過時間に基づいて、銑鉄の溶解量を推定する構成としている。
ここで、図３に示すように、溶解したと判断した時点からの経過時間と銑鉄の溶解量とは比例関係にあり、上述した銑鉄の溶解判定方法によって銑鉄が溶解したと判断された時点からの経過時間から銑鉄の溶解量を推定することが可能となる。
In addition, in the present embodiment of the method for estimating the amount of dissolved pig iron, the amount of dissolved pig iron is estimated based on the elapsed time from the point at which it is determined that the pig iron has been melted by the above-mentioned pig iron melting determination method.
Here, as shown in Figure 3, the amount of dissolved pig iron is proportional to the time elapsed from the time it is determined that the pig iron has melted, and it is possible to estimate the amount of dissolved pig iron from the time elapsed from the time it is determined that the pig iron has melted using the above-mentioned pig iron melting determination method.
以上のような構成とされた本実施形態である銑鉄の溶解判定方法によれば、銑鉄溶解処理中に発生する排ガス中の実測二酸化炭素濃度あるいは実測酸素濃度と、排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から算出される排ガス中の理論二酸化炭素濃度あるいは理論酸素濃度と、を比較し、実測二酸化炭素濃度が理論二酸化炭素濃度よりも一定以上高くなった際、あるいは、実測酸素濃度が理論酸素濃度よりも一定以上低くなった際に、銑鉄が溶解したと判断する構成としているので、銑鉄の溶解の有無を判定することができる。
そして、理論二酸化炭素濃度及び理論酸素濃度を算出する際に、侵入空気量を考慮していることから、トーピードカー等の開放された空間における銑鉄の溶解の有無を精度良く判定することが可能となる。
According to the method for determining whether pig iron has melted, which is the present embodiment configured as described above, the actual carbon dioxide concentration or the measured oxygen concentration in the exhaust gas generated during the pig iron melting process is compared with the theoretical carbon dioxide concentration or the theoretical oxygen concentration in the exhaust gas calculated from the exhaust gas temperature, the supporting gas flow rate, the fuel flow rate and the amount of invading air, and when the actual carbon dioxide concentration becomes higher than the theoretical carbon dioxide concentration by a certain amount or more, or when the actual oxygen concentration becomes lower than the theoretical oxygen concentration by a certain amount or more, it is determined that the pig iron has melted, so that it is possible to determine whether the pig iron has melted or not.
Furthermore, since the amount of invading air is taken into consideration when calculating the theoretical carbon dioxide concentration and the theoretical oxygen concentration, it is possible to accurately determine whether or not pig iron has dissolved in an open space such as a torpedo car.
本実施形態である銑鉄の溶解判定方法において、実測二酸化炭素濃度が理論二酸化炭素濃度よりも３ｖｏｌ％以上高くなった時点、あるいは、実測酸素濃度が理論酸素濃度よりも３ｖｏｌ％以上低くなった時点で、銑鉄が溶解したと判断する構成とした場合には、実測二酸化炭素濃度と理論二酸化炭素濃度との間、あるいは、実測酸素濃度と理論酸素濃度との間に明確な差異が生じており、的確に銑鉄の溶解の有無を判定することが可能となる。 In the present embodiment, the method for determining whether pig iron has dissolved is configured to determine whether pig iron has dissolved when the measured carbon dioxide concentration is 3 vol% or more higher than the theoretical carbon dioxide concentration, or when the measured oxygen concentration is 3 vol% or more lower than the theoretical oxygen concentration. This creates a clear difference between the measured carbon dioxide concentration and the theoretical carbon dioxide concentration, or between the measured oxygen concentration and the theoretical oxygen concentration, making it possible to accurately determine whether pig iron has dissolved.
また、本実施形態である銑鉄の溶解処理方法においては、上述した銑鉄の溶解判定方法によって銑鉄が溶解したと判断された際に、助燃ガス流量及び燃料流量の一方又は両方を調整し、排ガス中の酸素濃度を低下させる構成としているので、溶解した銑鉄（溶銑）と酸素の反応によってスラグが多量に生成することを抑制でき、耐火物の劣化を抑制することが可能となる。 In addition, in the pig iron melting treatment method of this embodiment, when it is determined that the pig iron has melted by the pig iron melting determination method described above, one or both of the flow rates of the supporting gas and the fuel are adjusted to reduce the oxygen concentration in the exhaust gas. This makes it possible to prevent a large amount of slag from being generated by the reaction between the molten pig iron (molten pig iron) and oxygen, and to suppress deterioration of the refractory material.
さらに、本実施形態である銑鉄の溶解量推定方法においては、上述した銑鉄の溶解判定方法によって銑鉄が溶解したと判断された時点からの経過時間に基づいて、銑鉄の溶解量を推定する構成としているので、銑鉄の溶解量（溶銑量）を精度良く推定することが可能となる。 Furthermore, in the present embodiment of the method for estimating the amount of dissolved pig iron, the amount of dissolved pig iron is estimated based on the time elapsed from the point at which it is determined that the pig iron has melted by the pig iron melting determination method described above, so that it is possible to accurately estimate the amount of dissolved pig iron (amount of molten pig iron).
以上、本発明の実施形態である本実施形態である銑鉄の溶解判定方法、及び、この銑鉄の溶解判定方法を利用した銑鉄の溶解処理方法、銑鉄の溶解量推定方法について説明したが、本発明はこれに限定されることはなく、その発明の技術的思想を逸脱しない範囲で適宜変更可能である。 The above describes the pig iron melting determination method, which is an embodiment of the present invention, and the pig iron melting treatment method and pig iron melting amount estimation method that utilize this pig iron melting determination method, but the present invention is not limited to this and can be modified as appropriate within the scope of the technical concept of the invention.
Claims (6)
銑鉄溶解処理中に発生する排ガスをサンプリングして測定した実測二酸化炭素濃度と、
排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から算出される排ガス中の理論二酸化炭素濃度と、
を比較し、前記実測二酸化炭素濃度が前記理論二酸化炭素濃度よりも一定以上高くなった際に、前記銑鉄が溶解したと判断することを特徴とする銑鉄の溶解判定方法。 A method for determining whether or not solidified pig iron has melted when the pig iron is melted in a transfer vessel for transferring molten iron, comprising the steps of:
The actual carbon dioxide concentration measured by sampling the exhaust gas generated during the pig iron melting process,
A theoretical carbon dioxide concentration in the exhaust gas calculated from the exhaust gas temperature, the combustion support gas flow rate, the fuel flow rate, and the amount of invading air;
and when the measured carbon dioxide concentration becomes higher than the theoretical carbon dioxide concentration by a certain amount or more, it is determined that the pig iron has melted.
銑鉄溶解処理中に発生する排ガスをサンプリングして測定した実測酸素濃度と、
排ガス温度、助燃ガス流量、燃料流量及び侵入空気量から算出される排ガス中の理論酸素濃度と、
を比較し、前記実測酸素濃度が前記理論酸素濃度よりも一定以上低くなった際に、前記銑鉄が溶解したと判断することを特徴とする銑鉄の溶解判定方法。 A method for determining whether or not solidified pig iron has melted when the pig iron is melted in a transfer vessel for transferring molten iron, comprising the steps of:
The actual oxygen concentration measured by sampling the exhaust gas generated during the pig iron melting process,
A theoretical oxygen concentration in the exhaust gas calculated from the exhaust gas temperature, the combustion support gas flow rate, the fuel flow rate, and the amount of invading air;
and judging that the pig iron has melted when the actual measured oxygen concentration becomes lower than the theoretical oxygen concentration by a certain amount or more.
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