JP4167374B2 - Coke oven operation method - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、コークス炉の操業方法に関し、特に、コークス炉の損傷低減及びコークス押し出し性の向上のためのコークス炉の操業方法に関するものである。
【０００２】
【従来の技術】
コークス炉の炭化室で石炭を乾留してコークスを製造する過程で、石炭は加熱されることにより膨張し、コークス炉の炉壁に圧力を及ぼすが、この圧力のことを一般に膨張圧と呼んでいる。この膨張圧が異常に高くなると、コークス炉の炉壁が直接損傷して操業不能になったり、コークスの炭化室から炉外への排出時（押し出し時）に抵抗（押し出し抵抗）が増大し、炉壁に過大な負荷を加えることにより、炉壁損傷の原因となる。
このため、コークス炉の操業において膨張圧をコークス炉損傷の許容限界値以下に管理することは、重要な課題である。特に、近年コークス炉の老朽化が進み、炉体強度が低下することにより許容限界値が低下するとともに、近年の調湿炭法などの石炭事前処理技術の導入によりコークス炉炭化室内の石炭装入嵩密度が上昇し、膨張圧は増加傾向にあり、コークス炉の延命のために膨張圧管理はますます重要な課題となっている。
【０００３】
従来、膨張圧は実コークス炉では測定できないため、石炭の揮発分、炭素含有率、平均反射率で表される石炭化度、もしくは全膨張率や最高流動度等で表される粘結性パラメータで膨張圧を推定することが試みられているが、これらの石炭性状だけから推定した膨張圧と実際の膨張圧とは格差があり、実用レベルでの膨張圧の推定はできなかった。
そのため、特開平５−２５５６７０号公報で開示されているように、所定の配合炭を実コークス炉に装入する前に、例えば、可動壁炉と呼ばれる片側の壁が可動式の特殊な試験乾留炉等を用いて、予め、所定の配合炭の乾留時の膨張圧を測定したり、本発明者らが特開平１１−３０２６６１号公報で提案したように、配合炭を構成する各銘柄石炭別に、予め試験乾留炉によって膨張圧を測定し、配合炭に対する予め測定した各銘柄石炭単味の膨張圧の相加平均値をもとに配合炭の膨張圧を推定し、配合炭の膨張圧が炉壁の損傷が起きない許容限界圧以下になるように原料炭の配合銘柄及び配合割合を調整していた。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記の特開平５−２５５６７０号公報で開示されている配合炭別に予め試験炉で膨張圧を測定しその管理をする方法は、コークスの品質調整のために急に原料炭の配合変更が生じた場合や、原料炭調達や原料炭の搬送設備に突然のトラブルがあり、原料炭の配合を急に変更せざるをえない場合に迅速な対応ができない。また、上記のような急な原料炭の配合変更時に迅速に対応するために、想定される全ての原料炭の配合組合せについて、予め、試験炉で膨張圧を測定し、膨張圧マップを作成することは、配合炭の種類が多数にあることから、多大な労力と時間を要することとなり、実用的ではない。
【０００５】
また、上記の本発明者らが特開平１１−３０２６６１号公報で提案した予め試験炉で測定した各銘柄石炭の膨張圧の配合炭に対する相加平均値をもとに配合炭の膨張圧を推定し、その膨張圧を原料炭の配合調整で制御する方法については、上記の特開平５−２５５６７０号公報で開示の方法に比べると、原料炭の配合変更時にも迅速な対応が可能であり非常に有効な方法ではあるものの、コークス強度等のコークス品質を維持するために配合に制約を受けるという問題点があった。
すなわち、一般的に膨張圧が高い石炭は低揮発分でイナート含有量の少い粘結炭であるが、これらの石炭はコークス強度を維持するのに重要な石炭でもあるため、場合によっては、コークス強度を維持しながらこれらの石炭の配合割合を制約することが困難な場合が生じるのである。
【０００６】
本発明は、従来の配合炭を構成する各銘柄石炭の膨張圧の相加平均値から配合炭の膨張圧を推定する際に、膨張圧の低い単味炭の配合割合を増やす代わりに、簡便な膨張圧の低減方法を用いることで膨張圧を低減し、膨張圧を安定的且つ確実に、コークス炉が損傷しない許容限界値以下に制御し、かつ一定強度以上のコークスを製造するためのコークス炉操業方法を提供することを目的とするものである。
【０００７】
【課題を解決するための手段】
本発明の要旨は、
（１）複数銘柄の石炭を配合した配合炭を用いたコークス炉の操業方法において、前記配合炭を構成するそれぞれの銘柄の石炭の最大膨張圧の重み付き平均値（Σpi xi ）、非微粘結炭の配合率（Ｘ）、および粘結炭のみの配合炭の全膨張率（ＴＤ）、粘結剤添加率（ｙ）から式（１）により配合炭膨張圧（Ｐｘ）を算出し、この算出配合炭膨張圧（Ｐｘ）を、あらかじめ定めたコークス炉の許容限界圧以下にするように、石炭の銘柄および配合割合を変えずに、粘結剤添加率（但し、０重量％を除く）を調整することを特徴とするコークス炉の操業方法。
Px ＝[a・Σpi xi -b・Σpi xi ・（X+c・X2
) ・{1+1/(d・TD+e)}+f］・(1-g・y)
・・・・・（１）
ただし
Px ：非微粘結炭をＸ％含む配合炭の推定膨張圧（ｋＰａ）
pi ：試験乾留炉によって測定した単味炭ｉの最大膨脹圧（ｋＰａ）
xi ：単味炭ｉの配合割合（−）
Σpi xi ：配合炭を構成するそれぞれの単味炭ｉの最大膨張圧の重み付き平均値（ｋＰａ）
X：非微粘結炭の配合割合（％）
TD ：粘結炭のみの配合炭の粘結性パラメータである全膨張率（％）
y：対石炭あたりの粘結剤添加率（％）
a,b,c,d,e,f,g：試験乾留炉によって測定した配合炭の膨張圧を基に得られた定数
【０００８】
（２）粘結剤がヘキサンに可溶な成分を１０ｗｔ％以上含み、且つ炭素が８５ｗｔ％以上含有するものであることを特徴とする上記（１）に記載のコークス炉の操業方法。
（３）粘結剤がタールからなることを特徴とする上記（２）記載のコークス炉の操業方法。
にある。
【０００９】
【発明の実施の形態】
本発明者は、先に特開平１１−３０２６６１号公報で提案した膨張圧の低減方法を基に、従来の問題点であるコークス強度の低下をさせることなく、膨張圧を低減させる方法を鋭意検討した結果、コークス炉に装入する配合炭に粘結剤を添加することが有効であることを見出した。
石炭は、乾留過程において軟化溶融した後に再固化してコークスとなるが、膨張圧の発生要因は軟化溶融した石炭層内にトラップされた石炭の熱分解ガスの圧力である。軟化溶融した石炭層の粘度は非常に高いため、発生ガスは容易に抜けることはできず、内部にトラップされる。そのためガスの圧力が上昇し、この圧力がコークス層を介して、膨張圧としてコークス炉壁に作用する。
したがって、軟化溶融した石炭層内のガスの圧力を低下せしめれば、膨張圧を低減することができる。発明者らは、粘結剤を添加することにより、軟化溶融した石炭層内のガスの圧力が低下することを見出した。これは、粘結剤を添加することにより、軟化溶融した石炭層の粘度が低下するためと考えられる。
【００１０】
また本発明者は、粘結剤の添加量に比例して膨張圧が低下することを見出した。例えば、図１に粘結剤添加率と配合炭膨張圧の関係を示す。粘結剤がタールの場合、対石炭あたり１重量％添加すると膨張圧は１０％、３重量％添加では３０％低下した。また、本発明者は、ある一定値（効果飽和上限値）以上に添加率を上げても膨張圧低減効果は飽和することを見出した。
図１に示すように、粘結剤がタールの場合、添加率を５％以上に上げても膨張圧低減効果は変化しない。
【００１１】
本発明者は、先に特開平１１−３０２６６１号公報において、配合炭を構成するそれぞれの銘柄の石炭の最大膨張圧の相加平均値（Σpixi）、非微粘結炭の配合率（Ｘ）、および粘結炭のみの配合炭の全膨張率（ＴＤ）から下式（２）により配合炭膨張圧を算出し、この算出配合炭膨張圧を、あらかじめ定めたコークス炉の許容限界圧以下にするように、石炭の銘柄及び配合割合を調整する膨張圧の低減方法を提案した。
【００１２】
Px' ＝a・Σpi xi -b・Σpi xi ・（X+c・X2
) ・{1+1/(d・TD+e)}+f
・・・・・（２）
ただし
Px' ：非微粘結炭をＸ％含む配合炭の推定膨張圧（ｋＰａ）
pi ：試験乾留炉によって測定した単味炭ｉの最大膨脹圧（ｋＰａ）
xi ：単味炭ｉの配合割合（−）
Σpi xi ：配合炭を構成するそれぞれの単味炭ｉの最大膨張圧の重み付き平均値（ｋＰａ）
X：非微粘結炭の配合割合（％）
TD ：粘結炭のみの配合炭の粘結性パラメータである全膨張率（％）
a,b,c,d,e,f：試験乾留炉によって測定した配合炭の膨張圧を基に得られた定数
【００１３】
しかしながら、上記の特開平１１−３０２６６１号公報においては、図２に示す非微粘結炭の配合割合と配合炭膨張圧との関係、非微粘結炭の配合割合とコークス強度の関係の通り、非微粘結炭の配合割合を増加することによって配合炭の膨張圧は低下するものの、コークス強度も低下して（特に非微粘結炭配合率が４０％以上で急激に低下）、高炉で使用するための必要強度が得られなくなるという問題があった。
本発明では、上記（２）式を基にして、さらに下記（１）式の関係に基づいて粘結剤を所定量添加することによりコークス強度の低下をさせることなく、許容限界圧以下にまで膨張圧を低減できるものである。
【００１４】
Px ＝Px'・(1-g・y)
＝[a・Σpi xi -b・Σpi xi ・（X+c・X2
) ・{1+1/(d・TD+e)}+f］・(1-g・y)
・・・・・（１）
ただし
Px ：非微粘結炭をＸ％含む配合炭の推定膨張圧（ｋＰａ）
pi ：試験乾留炉によって測定した単味炭ｉの最大膨脹圧（ｋＰａ）
xi ：単味炭ｉの配合割合（−）
Σpi xi ：配合炭を構成するそれぞれの単味炭ｉの最大膨張圧の重み付き平均値（ｋＰａ）
X：非微粘結炭の配合割合（％）
TD ：粘結炭のみの配合炭の粘結性パラメータである全膨張率（％）
y：対石炭あたりの粘結剤添加率（％）
a,b,c,d,e,f,g：試験乾留炉によって測定した配合炭の膨張圧を基に得られた定数
【００１５】
つまり、本発明では、配合炭を構成するそれぞれの銘柄の石炭の最大膨張圧の相加平均値（Σpixi）、非微粘結炭の配合率（Ｘ）、および粘結炭のみの配合炭の全膨張率（ＴＤ）、粘結剤添加率（ｙ）から上記の（１）式により配合炭膨張圧を算出し、この算出配合炭膨張圧を、あらかじめ定めたコークス炉の許容限界圧以下にするように、石炭の銘柄、配合割合および粘結剤添加率を調整すればよい。
粘結剤としては、ヘキサンに可溶な成分を１０ｗｔ％以上含み、炭素含有率が８５ｗｔ％以上の粘結剤を用いればよい。またこのような粘結剤としては、例えばタール等がある。
【００１６】
図３は、粘結剤としてタールを３％添加した場合の非微粘結炭の配合割合と配合炭膨張圧との関係、非微粘結炭の配合割合とコークス強度の関係を比較した図である。図より、本発明により粘結剤を添加することにより非微粘結炭配合率が７０％までコークスの必要強度を維持しつつ膨張圧を低減できることが判る。
本発明において、配合炭の非微粘結炭の配合割合は、コークスの必要強度及び必要膨張圧によって（１）によって調整されるが、通常知られているコークス押し出し性が良好な膨張圧（許容限界膨張圧）：１０ｋＰａ以下で、コークス強度（ドラム強度指数）８３以上のコークスを得るためには、配合炭の非微粘結炭の配合割合を７０％以下とすることが好ましい。配合炭の非微粘結炭の配合割合が７０％を越えると、膨張圧は低下して良好なコークス押し出し性は得られるが、高炉で使用する際に必要とするコークス強度が得られないためである。
【００１７】
【実施例】
表１の比較例１は、Ａ炭〜Ｇ炭によって構成される配合炭の推定膨張圧Pxが、コークス炉の許容限界膨張圧（１０ｋＰａ）により近い配合の例である。
ここで推定膨張圧の計算には、（１）式を用い、（１）式における係数は、以下の値を用いた。
a'＝0.795064, b'＝0.004087, c'＝−0.0040476,
d'＝0.00986, e'＝−0.2112, f'＝−5.9394, g＝0.1
【００１８】
【表１】
比較例１においては配合炭の膨張圧推定値は８．１ｋＰａであった。そして、この配合炭をコークス炉で乾留した後、押出し機で押し出した際の押出し負荷ピーク電流は２８５Ａで、押出し負荷ピーク電流値の許容上限値３００Ａ以下ではあるが、安定操業を行っている場合と比較して大きく、炭化室の炉壁に大きな負荷がかかっていることが推定される。コークス強度はＪＩＳ Ｋ２１５１に記載のドラム強度試験法により測定されるドラム強度指数で８４．５であり、十分な強度を有していた。
【００２０】
比較例２は、配合炭の推定膨張圧Pxが、コークス炉の許容限界膨張圧（１０ｋＰａ）よりも充分下回るように、比較例１の配合炭中の最大膨張圧の高いＡ炭を低下させ、最大膨張圧の低いＧ炭を増加するような配合調整した例である。
比較例２の配合炭の膨張圧推定値は３．６ｋＰａとなり、比較例１に比べて低くなり、この配合炭をコークス炉で乾留した後、押出し機で押し出した際の押出し負荷ピーク電流も２５０Ａとなり、押出し負荷ピーク電流値の許容上限値３００Ａ以下であり、安定操業であった。しかしながら、ドラム強度指数は８３．５と低くなり、結果的に比較例１に比べて膨張圧は低減できたものの、強度は著しく低下した。
【００２１】
発明例は、比較例２のように配合炭中の石炭の配合を変えずに比較例１と同じ配合で、粘結剤としてタールを５重量％添加した場合である。この配合炭をコークス炉で乾留した後、押出し機で押し出した際の押出し負荷ピーク電流は２４５Ａで、押出し負荷ピーク電流値の許容上限値３００Ａよりも非常に低くなり、安定操業ができた。また、ドラム強度指数も８４．８であり、十分な強度を有するコークスであった。
以上の実施例から、本発明により、コークスの必要強度を維持し、かつ膨張圧を低減してコークス押し出し性を良好にすることが可能であることがわかる。
【００２２】
【発明の効果】
本発明により、簡便な方法でコークス強度を維持ながら膨張圧を目標値以下に低減でき、コークス炉壁に損傷を与えることなく安定したコークス炉操業を継続することができる。これにより、コークス炉の補修費用が低減されるとともに、押詰りなどによる生産トラブルが回避でき、その経済的効果は極めて大きい。
【図面の簡単な説明】
【図１】粘結剤添加率と配合炭膨張圧の関係を示す図である。
【図２】非微粘結炭の配合率と配合炭膨張圧、コークス強度の関係を示す図である。
【図３】本発明の粘結剤としてタールを３％添加した場合における、非微粘結炭の配合率と配合炭膨張圧、コークス強度の関係を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for operating a coke oven, and more particularly to a method for operating a coke oven for reducing damage to the coke oven and improving coke extrusion.
[0002]
[Prior art]
In the process of producing coke by carbonizing coal in a coke oven, the coal expands when heated and exerts pressure on the coke oven wall. This pressure is generally called expansion pressure. Yes. If this expansion pressure becomes abnormally high, the furnace wall of the coke oven will be damaged directly, making it impossible to operate, or the resistance (extrusion resistance) will increase when the coke is discharged from the carbonization chamber (extruding), If an excessive load is applied to the furnace wall, it will cause damage to the furnace wall.
For this reason, it is an important issue to manage the expansion pressure below the allowable limit value for coke oven damage in the operation of the coke oven. In particular, coke ovens have become aging in recent years, and the allowable limit value is lowered due to a decrease in furnace body strength. In addition, the introduction of coal pretreatment technology such as the humidity-controlling coal method in recent years has led to the introduction of coal into the coke oven carbonization chamber. As the bulk density rises and the expansion pressure is on the rise, expansion pressure management is becoming an increasingly important issue for extending the life of coke ovens.
[0003]
Conventionally, the expansion pressure cannot be measured in an actual coke oven, so the coal volatile matter, carbon content, coalification degree expressed by average reflectance, or cohesiveness parameter expressed by total expansion rate, maximum fluidity, etc. Attempts have been made to estimate the expansion pressure, but there was a difference between the expansion pressure estimated from these coal properties and the actual expansion pressure, and it was not possible to estimate the expansion pressure at a practical level.
Therefore, as disclosed in Japanese Patent Application Laid-Open No. 5-255670, before charging a predetermined blended coal into an actual coke oven, for example, one side wall called a movable wall oven is a movable special test dry distillation furnace Or the like, in advance, the expansion pressure at the time of dry distillation of the predetermined blended coal, or as proposed by the present inventors in Japanese Patent Laid-Open No. 11-302661, for each brand coal constituting the blended coal, The expansion pressure of the blended coal is estimated based on the arithmetic average value of the expansion pressure of each brand of coal that has been measured in advance with respect to the blended coal. The blending brand and blending ratio of the raw coal were adjusted so that the wall pressure would not exceed the permissible limit pressure.
[0004]
[Problems to be solved by the invention]
However, the method of measuring the expansion pressure in a test furnace in advance for each blended coal disclosed in JP-A-5-255670 and managing it is a sudden change in the blend of coking coal for coke quality adjustment. If this occurs, or if there is a sudden problem in the procurement of coking coal and the transportation equipment for coking coal, the blending of coking coal must be changed abruptly, it is impossible to respond quickly. In addition, in order to quickly respond to the sudden change in the raw coal composition as described above, the expansion pressure is measured in advance in a test furnace and the expansion pressure map is created for all possible raw coal combinations. This means that since there are many types of blended coal, a great deal of labor and time is required, which is not practical.
[0005]
Further, the expansion pressure of the blended coal is estimated based on the arithmetic average value of the expansion pressure of each brand coal previously measured in the test furnace proposed in Japanese Patent Application Laid-Open No. 11-302661 by the above-mentioned inventors. However, the method for controlling the expansion pressure by adjusting the mixing ratio of the raw coal is much faster than the method disclosed in the above Japanese Patent Application Laid-Open No. 5-255670. Although it is an effective method, there is a problem that the composition is restricted in order to maintain the coke quality such as coke strength.
In other words, generally coal with high expansion pressure is caking coal with low volatile content and low inert content, but these coals are also important coals for maintaining coke strength. In some cases, it is difficult to restrict the blending ratio of these coals while maintaining the coke strength.
[0006]
When estimating the expansion pressure of blended coal from the arithmetic mean value of the expansion pressure of each brand coal constituting the conventional blended coal, the present invention is simple, instead of increasing the blending ratio of simple coal having a low expansion pressure. Coke to reduce the expansion pressure by using a method for reducing the expansion pressure, to control the expansion pressure stably and reliably below the allowable limit value that does not damage the coke oven, and to produce coke with a certain strength or more The purpose is to provide a furnace operation method.
[0007]
[Means for Solving the Problems]
The gist of the present invention is as follows:
(1) In a method for operating a coke oven using a blended coal containing a plurality of brands of coal, a weighted average value (Σpi xi) of the maximum expansion pressure of each brand of coal constituting the blended coal, non-slight viscosity The blended coal expansion pressure (Px) is calculated by the formula (1) from the blended rate of coal (X), and the total expansion rate (TD) of the blended coal only of caking coal, and the binder addition rate (y). Binder addition rate (excluding 0% by weight) without changing the coal brand and blending ratio so that the calculated blended coal expansion pressure (Px) is lower than the allowable limit pressure of the coke oven. Coke oven operating method characterized by adjusting the
Px = [a ・ Σpi xi -b ・ Σpi xi ・ (X + c ・ X 2
) ・ {1 + 1 / (d ・ TD + e)} + f] ・ (1-g ・ y)
(1)
However,
Px: Estimated expansion pressure (kPa) of blended coal containing X% non-coking coal
pi: Maximum expansion pressure (kPa) of simple coal i measured by a test carbonization furnace
xi: Mixing ratio of simple coal i (-)
Σpi xi: Weighted average value (kPa) of the maximum expansion pressure of each simple coal i constituting the blended coal
X: Mixing ratio of non-slightly caking coal (%)
TD: Total expansion rate (%), which is a caking property parameter of blended coal with caking coal only
y: Binder addition rate per coal (%)
a, b, c, d, e, f, g: Constant [0008] obtained on the basis of the inflation pressure of the coal blend, as measured by a test carbonization furnace
(2) The method for operating a coke oven according to (1) above, wherein the binder contains 10 wt% or more of a component soluble in hexane and 85 wt% or more of carbon.
(3) The coke oven operating method as described in (2) above, wherein the binder is tar.
It is in.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present inventor has intensively studied a method for reducing the expansion pressure without reducing the coke strength, which is a conventional problem, based on the method for reducing the expansion pressure previously proposed in JP-A-11-302661. As a result, it has been found that it is effective to add a binder to the blended coal charged into the coke oven.
Coal is softened and melted in the process of carbonization and then re-solidified into coke. The cause of the expansion pressure is the pressure of the pyrolysis gas of the coal trapped in the softened and melted coal bed. Since the softened and melted coal layer has a very high viscosity, the generated gas cannot easily escape and is trapped inside. Therefore, the pressure of the gas rises, and this pressure acts on the coke oven wall as an expansion pressure through the coke layer.
Therefore, if the pressure of the gas in the softened and melted coal bed is lowered, the expansion pressure can be reduced. The inventors have found that by adding a binder, the pressure of the gas in the softened and melted coal bed is lowered. This is presumably because the viscosity of the softened and melted coal layer is reduced by adding a binder.
[0010]
The inventor has also found that the expansion pressure decreases in proportion to the amount of binder added. For example, FIG. 1 shows the relationship between the binder addition rate and the coal blend expansion pressure. When the binder is tar, the expansion pressure is reduced by 10% when added to coal by 1% by weight and by 30% when added by 3% by weight. Further, the present inventor has found that the expansion pressure reduction effect is saturated even when the addition rate is increased to a certain value (effect saturation upper limit) or more.
As shown in FIG. 1, when the binder is tar, the expansion pressure reduction effect does not change even if the addition rate is increased to 5% or more.
[0011]
The present inventor previously disclosed an arithmetic mean value (Σp i x i ) of the maximum expansion pressures of coals of respective brands constituting the coal blend, and a blending ratio of non-slightly caking coal in Japanese Patent Laid-Open No. 11-302661. (X) and the total expansion rate (TD) of the coal mixture containing only caking coal, the blended coal expansion pressure is calculated by the following formula (2), and this calculated blended coal expansion pressure is set as a predetermined allowable limit of the coke oven. We proposed a method for reducing the expansion pressure by adjusting the coal brand and blending ratio so that it is below the pressure.
[0012]
Px '= a ・ Σpi xi -b ・ Σpi xi ・ (X + c ・ X 2
) ・ {1 + 1 / (d ・ TD + e)} + f
(2)
However,
Px ': Estimated expansion pressure (kPa) of blended coal containing X% non-slightly caking coal
pi: Maximum expansion pressure (kPa) of simple coal i measured by a test carbonization furnace
xi: Mixing ratio of simple coal i (-)
Σpi xi: Weighted average value (kPa) of the maximum expansion pressure of each simple coal i constituting the blended coal
X: Mixing ratio of non-slightly caking coal (%)
TD: Total expansion rate (%), which is a caking property parameter of blended coal with caking coal only
a, b, c, d, e, f: constants obtained based on the expansion pressure of the blended coal measured by the test carbonization furnace
However, in the above-mentioned Japanese Patent Application Laid-Open No. 11-302661, the relationship between the blending ratio of non-slightly caking coal and the blended coal expansion pressure and the relationship between the blending ratio of non-slightly caking coal and coke strength shown in FIG. By increasing the blending ratio of non-slightly caking coal, the expansion pressure of blended coal decreases, but the coke strength also decreases (especially when the blending ratio of non-slightly caking coal is 40% or more), the blast furnace There is a problem that the required strength for use in the above cannot be obtained.
In the present invention, based on the above formula (2), a predetermined amount of a binder is further added based on the relationship of the following formula (1), so that the coke strength is not lowered, and the pressure falls below the allowable limit pressure. The expansion pressure can be reduced.
[0014]
Px = Px '・ (1-g ・ y)
= [A ・ Σpi xi -b ・ Σpi xi ・ (X + c ・ X 2
) ・ {1 + 1 / (d ・ TD + e)} + f] ・ (1-g ・ y)
(1)
However,
Px: Estimated expansion pressure (kPa) of blended coal containing X% non-coking coal
pi: Maximum expansion pressure (kPa) of simple coal i measured by a test carbonization furnace
xi: Mixing ratio of simple coal i (-)
Σpi xi: Weighted average value (kPa) of the maximum expansion pressure of each simple coal i constituting the blended coal
X: Mixing ratio of non-slightly caking coal (%)
TD: Total expansion rate (%), which is a caking property parameter of blended coal with caking coal only
y: Binder addition rate per coal (%)
a, b, c, d, e, f, g: Constants obtained based on the expansion pressure of the blended coal measured by the test carbonization furnace
That is, in the present invention, the arithmetic mean value (Σp i x i ) of the maximum expansion pressure of each brand of coal constituting the coal blend, the blending ratio (X) of non-slightly caking coal, and caking coal only The blended coal expansion pressure is calculated from the above formula (1) from the total expansion rate (TD) and the binder addition rate (y) of the blended coal, and this calculated blended coal expansion pressure is determined as a predetermined allowable limit of the coke oven. What is necessary is just to adjust the brand of a coal, a mixture ratio, and a binder addition rate so that it may become below pressure.
As the binder, a binder containing 10 wt% or more of a component soluble in hexane and having a carbon content of 85 wt% or more may be used. An example of such a binder is tar.
[0016]
FIG. 3 is a diagram comparing the relationship between the blending ratio of non-slightly caking coal and the blended coal expansion pressure when 3% of tar is added as a binder, and the relationship between the blending ratio of non-slightly caking coal and coke strength. It is. From the figure, it can be seen that by adding the binder according to the present invention, the expansion pressure can be reduced while maintaining the required strength of coke up to a non-slightly caking coal blending ratio of 70%.
In the present invention, the blending ratio of the non-slightly caking coal in the blended coal is adjusted by (1) according to the required strength and the necessary expansion pressure of coke. (Limit expansion pressure): In order to obtain coke having a coke strength (drum strength index) of 83 or more at 10 kPa or less, it is preferable that the blending ratio of the non-slightly caking coal in the blended coal is 70% or less. When the blending ratio of the non-slightly caking coal in the blended coal exceeds 70%, the expansion pressure decreases and good coke extrusion properties can be obtained, but the coke strength required when used in a blast furnace cannot be obtained. It is.
[0017]
【Example】
Comparative examples in Table 1 1, the estimated inflation pressure P x in coal blend constituted by A coal ~G coal are examples of formulations closer to the allowable limit inflation pressure of a coke oven (10 kPa).
Here, for the calculation of the estimated expansion pressure, equation (1) was used, and the following values were used as coefficients in equation (1).
a ′ = 0.795064, b ′ = 0.04087, c ′ = − 0.0040476,
d ′ = 0.00986, e ′ = − 0.2112, f ′ = − 5.9394, g = 0.1
[0018]
[Table 1]
In Comparative Example 1, the estimated expansion pressure of the blended coal was 8.1 kPa. And after dry-blending this blended coal in a coke oven, the extrusion load peak current when extruding with an extruder is 285A, which is less than the allowable upper limit 300A of the extrusion load peak current value, but when stable operation is performed It is estimated that a large load is applied to the furnace wall of the carbonization chamber. The coke strength was 84.5 as a drum strength index measured by the drum strength test method described in JIS K2151, and had a sufficient strength.
[0020]
Comparative Example 2 is estimated inflation pressure P x in the coal blend is as below sufficiently than the permissible limit inflation pressure of a coke oven (10 kPa), to reduce the high A coal of maximum expansion pressure of the formulation in charcoal Comparative Example 1 It is an example of blending adjustment to increase G charcoal having a low maximum expansion pressure.
The estimated expansion pressure of the blended coal of Comparative Example 2 is 3.6 kPa, which is lower than that of Comparative Example 1, and the extrusion load peak current when the blended coal is carbonized in a coke oven and then extruded with an extruder is 250 A. Thus, the allowable upper limit of the extrusion load peak current value was 300 A or less, and the operation was stable. However, the drum strength index was as low as 83.5. As a result, although the expansion pressure could be reduced as compared with Comparative Example 1, the strength was significantly reduced.
[0021]
The invention example is a case where 5 wt% of tar is added as a binder with the same composition as Comparative Example 1 without changing the composition of coal in the blended coal as in Comparative Example 2. When this blended charcoal was carbonized in a coke oven and then extruded with an extruder, the extrusion load peak current was 245 A, which was much lower than the allowable upper limit 300 A of the extrusion load peak current value, and stable operation was possible. Further, the drum strength index was 84.8, which was a coke having a sufficient strength.
From the above examples, it can be seen that according to the present invention, the required strength of coke can be maintained and the expansion pressure can be reduced to improve the coke extrusion property.
[0022]
【The invention's effect】
According to the present invention, the expansion pressure can be reduced below the target value while maintaining the coke strength by a simple method, and stable coke oven operation can be continued without damaging the coke oven wall. As a result, the cost for repairing the coke oven is reduced, and production troubles such as clogging can be avoided, and the economic effect is extremely large.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a binder addition rate and a coal mixture expansion pressure.
FIG. 2 is a graph showing the relationship between the blending ratio of non-slightly caking coal, blending coal expansion pressure, and coke strength.
FIG. 3 is a diagram showing the relationship between the blending ratio of non-slightly caking coal, blended coal expansion pressure and coke strength when 3% of tar is added as the binder of the present invention.
Claims (3)
Px ＝[a・Σpi xi -b・Σpi xi ・（X+c・X2 ) ・{1+1/(d・TD+e)}+f］・(1-g・y)
・・・・・（１）
ただし
Px ：非微粘結炭をＸ％含む配合炭の推定膨張圧（ｋＰａ）
pi ：試験乾留炉によって測定した単味炭ｉの最大膨脹圧（ｋＰａ）
xi ：単味炭ｉの配合割合（−）
Σpi xi ：配合炭を構成するそれぞれの単味炭ｉの最大膨張圧の重み付き平均値（ｋＰａ）
X：非微粘結炭の配合割合（％）
TD ：粘結炭のみの配合炭の粘結性パラメータである全膨張率（％）
y：対石炭あたりの粘結剤添加率（％）
a,b,c,d,e,f,g：試験乾留炉によって測定した配合炭の膨張圧を基に得られた定数In a coke oven operating method using blended coal containing multiple brands of coal, the weighted average value (Σpi xi) of the maximum expansion pressure of each brand of coal constituting the blended coal, The blending charcoal expansion pressure (Px) is calculated by the formula (1) from the blending ratio (X), the total expansion coefficient (TD) of the blended charcoal containing only caking coal, and the binder addition ratio (y). Adjust the binder addition rate (excluding 0% by weight) without changing the coal brand and blending ratio so that the coal expansion pressure (Px) is less than the allowable limit pressure of the coke oven. A method of operating a coke oven, characterized by:
Px = [a · Σpi xi -b · Σpi xi · (X + c · X 2) · {1 + 1 / (d · TD + e)} + f] · (1-g · y)
(1)
However,
Px: Estimated expansion pressure (kPa) of blended coal containing X% non-coking coal
pi: Maximum expansion pressure (kPa) of simple coal i measured by a test carbonization furnace
xi: Mixing ratio of simple coal i (-)
Σpi xi: Weighted average value (kPa) of the maximum expansion pressure of each simple coal i constituting the blended coal
X: Mixing ratio of non-slightly caking coal (%)
TD: Total expansion rate (%), which is a caking property parameter of blended coal with caking coal only
y: Binder addition rate per coal (%)
a, b, c, d, e, f, g: Constants obtained based on the expansion pressure of the blended coal measured in the test carbonization furnace
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|---|---|---|---|
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|---|---|---|---|
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| JP4751408B2 (en) * | 2008-02-14 | 2011-08-17 | 新日本製鐵株式会社 | Method for producing blast furnace coke |
| JP6227482B2 (en) | 2014-05-28 | 2017-11-08 | 株式会社神戸製鋼所 | Method for producing blast furnace coke and blast furnace coke |
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