JP3541552B2 - Operating method of coke oven - Google Patents

Description

【００１３】
【発明の実施の形態】
この発明の作用を以下に詳細に述べる。
通常のコークス炉操業においては、押出しラムによってコークスケーキを片側（マシンサイド）から押して排出する。その際、押出し機の能力や炉壁保護のために決められた押力の最大許容値を超える場合に、電気的に押出しを中断、あるいは中止するのが押出し不良である。実機でのコークスケーキの押出しを原料炭装入孔から観察した結果、押出しラムによって押力が与えられると、コークスケーキは横方向（炉壁方向）に拡がりながら押出され、この横方向の拡がりが著しくなると押出し不良に到ることが判明した。これは、コークスケーキの押出し中に横方向への拡がりによって炉壁に荷重が作用すると、壁面との摩擦によってコークスケーキを排出する推力が減少するためである。すなわち、押力に対する炉壁荷重の比（以下、βという）が一定値を超えると押力がその最大許容値になってもコークスケーキの押出しに必要な推力が得られず、押出し不良に至ると考えられる。
【００１４】
この発明は、これらの知見にもとづいて達成したもので、以下にその内容を述べる。
片側の炉壁と炉体との拘束をなくし、コークスケーキを押出しラムで圧縮したときの炉壁への荷重を測定できるようにした石炭乾留試験炉において、押出しラムの押力とコークスケーキ圧縮中の炉壁への荷重との関係を測定する実験を行った。
【００１５】
そこで、上記実験結果の１例として、コークスケーキの圧縮ひずみ（圧縮前コークスケーキ長さに対する圧縮変形量）とβ（炉壁負荷指数）および圧縮応力（圧縮中の押力を応力値に換算した値）との関係のグラフを図１に示す。
【００１６】
図１から明らかなように、コークスケーキの変形は、圧縮方向の変形量（圧縮ひずみ）の増加に従って、図１の点線で示すように４つの領域、すなわち、コークスケーキの変形抵抗（圧縮応力）が小さく安定している第１の領域、変形抵抗が上昇し始める第２の領域、βが発生し、その値が安定している第３の領域および変形抵抗と特にβが急増する第４の領域に分けることができ、コークスケーキの変形量（圧縮ひずみ）が一定値を超えると変形抵抗（圧縮応力）とβとが急激に増加することがわかる。
このコークスケーキの変形量がβの急増領域に入ると、押出し不良が発生する確率が高くなる。
【００１７】
そこで、種々の条件で実験を行った結果、β急増領域の境界の圧縮応力は、原料炭の配合（原料炭特性）や操業条件によらずほぼ一定であることがわかった。このことから、コークスケーキの変形がβの急増する領域、この場合押力６ｔ時の押力に対する炉壁荷重の比（以下、β_6tという）が、コークスケーキの押出し性をあらわす指標となることが判明した。
【００１８】
さらに、実験を重ねた結果、β_6tは原料炭の特性（粘結性、石炭化度、水分等）、乾留時間およびフリュー温度などの原料炭特性や操業条件と強い関係のあることがわかった。
【００１９】
一般にβ_6tは次式（２）で与えることができる。
β_6t＝ｆ（ P_1, P₂, P₃---） ---(2)
ここで、Ｐ_i は原料炭の特性（粘結性、石炭化度、水分）、乾留時間、フリュー温度、嵩密度および粒度などの原料炭特性および操業条件である。
【００２０】
たとえば、β_6tは、原料炭の最大流動度（以下、ＭＦという）、石炭化度（以下、ビトリニット平均反射率：
【外１】

という）の増加に伴って減少し、ＭＦおよび
【外２】

の関数として一般に次式（３）で与えることができる。
【数３】

ここで、ａ_c ，ｂ_c ，ｃ_c ，ｄ_c およびｅ_c は他の操業条件から決定される定数である。
【００２１】
なお、上記において、最大流動度、石炭化度の異なる石炭を複数配合して原料炭として使用する場合は、それらの配合比に基づいて荷重平均したＭＦ，
【外３】

を代表値として用いることでよい。
【００２２】
ついで、実験結果にもとづく、フリュー温度：１０００℃、乾留時間：１８時間、原料炭水分：６％の場合における
【外４】

をパラメーターとするβ_6tとＭＦとの関係のグラフを図２に示す。
【００２３】
図２から明らかなように、コークスケーキ圧縮中の炉壁荷重は、原料炭のＭＦ，
【外５】

の増加に伴い減少し、この場合β_6tはＭＦおよび
【外６】

の関数として次式（１）を得ることができる。
【数４】

【００２４】
さらに、乾留時間：ｔとβ_6tとの関係は一般に次式（４）で与えられる。
β_6t＝ａ_t （ｔ−ｂ_t )²＋ｃ_t ---(4)
ここで、ａ_t ，ｂ_t およびｃ_t は他の原料炭特性や操業条件から決定される定数である。
【００２５】
他の原料炭特性や操業条件の、原料炭の水分、嵩密度、粒度およびフリュー温度などについても、上記と同様なβ_6tとの一般的な関係式が得られる。これらの関係式を互いに組合せて上記（２）式を用いることによって、種々の条件におけるβ_6tが得られ、このβ_6tによってコークスケーキの押出し性を予測することができ、このβ_6tを指標とすることにより、コークスケーキの押出し不良が防止できることになる。
【００２６】
つぎに実機のコークス炉操業における、原料炭特性および操業条件とコークスケーキの押出し性との関係を調査した。対象としたコークス炉は、炉高：6.4m、炉幅：430mm 、奥行き：14.8m で、66門の炉団である。この炉団は炉令が約17年と若いため炉壁損傷はほとんど見られない。調査期間は１年間で、調査期間中の原料炭特性および操業条件は、
【外７】

＝0.87〜1.14、ＭＦ＝1.82〜2.98、原料炭水分：5.5 〜7.5 ％、炉温：1150〜1250℃および稼働率（１日１窯当りの押出し本数×100 ）：130 〜150 ％である。押出し性の評価は全窯における１日当りの押出し不良件数の合計とした。この押出し不良の発生頻度とコークスのタンブラー強度：ＴＩとの関係のグラフを図３に、押出し不良の発生頻度とそれぞれの原料炭特性および操業条件から前記（１）式で得られるβ_6tとの関係のグラフを図４に示す。
【００２７】
これらの図から明らかなように、コークスのＴＩ（タンブラー強度）と押出し不良の発生頻度との間には相関が見られず、これまで考えられていたようにコークス強度が増加するほど押出し不良が減少するとは一概には言えないことがわかる。それに対して、β_6tに関しては押出し不良の発生頻度との間に明確な相関が見られ、押出し不良が発生しないしきい値が存在することがわかる。この場合におけるしきい値はβ_6t＝0.05であるが、コークス炉の窯寸法や損傷程度等条件によってこのしきい値は変化する。
【００２８】
また、上記と異なる実機コークス炉（91門、炉高：5.9m、炉幅：460mm 、奥行き：14.9m)において、原料炭配合がコークス押出し性に及ぼす影響を調査する実験を行った。各実験は50窯について原料炭の配合以外の操業条件を同一にして行い、β_6tの算出には前記の(1) 式を用いた。原料炭の配合はβ_6tで0.01〜0.1 の10水準とし、β_6tが0.05と0.06の配合ではＭＦ、
【外８】

をそれぞれ５水準変えて行った。これらの実験結果を表１に示す。
【００２９】
【表１】

【００３０】
この場合においても、β_6t≦0.05となる原料炭特性および操業条件によってコークスの押出し不良を防止できることが判明した。
これらの結果から、(1) 式から計算されるβ_6tが同一となる原料炭特性および操業条件から得られるコークスケーキについては同一の押出し性を有し、異なる場合にはβ_6tが小さいほど押出しに有効な推力が増すため押出し性が向上することがわかった。
【００３１】
一方、コークスケーキの押出し中に発生する炉壁負荷とコークスケーキ内構造との関係を調査した結果、押出し中の炉壁負荷にはケーキ内の亀裂構造が大きく影響していることがわかった。さらに、石炭配合とケーキ内亀裂構造との関係を調査したところ、原料炭特性および操業条件が炉壁負荷の発生に関係する亀裂構造を支配していることが判明した。たとえば、原料炭の粘結性と石炭化度が増加することによってコークスケーキ内の構造が変化し、炉壁負荷を発生するケーキ内の運動が抑制される。
前記(1) 式の場合には原料炭の粘結性をあらわす指標としてＭＦを、石炭化度をあらわす指標として
【外９】

を用いたが、この発明では、粘結性をあらわす指標として例えば全膨張率、粘着度指数などを石炭化度をあらす指標として例えば揮発分量、発熱量などを用いてもよく、これらのいずれを用いても管理指標を構成する計算式が異なるだけで、本質的な相違はない。
【００３２】
また、一般にコークスケーキの押出し不良の発生原因には、炉の老巧化、炉壁や天井へのカーボン付着、炉壁損傷などが挙げられている。しかし、この発明を用いて原料炭特性や操業条件を適切に設計し、押出し中に発生する炉壁荷重を抑制するコークスケーキ構造とすることで、上記の諸因子下においても押出し不良の発生を防止することができる。すなわち、原料炭特性や操業条件からコークス押出し中の炉壁負荷をあらわす炉壁負荷指数を算出して、このしきい値を超えないように原料炭や操業の設計を行うことによって、コークスケーキ排出時の押出し性を確保し、押出し不良の発生、さらに押出し不良に伴うコークス炉の損傷を未然に防止することが可能になる。
【００３３】
【実施例】
実機コークス炉、（91門、炉高：5.9m、炉幅：460 mm、奥行き：14.9m)において、この発明に従う設計による操業試験を３月間実施し、従来の操業との比較を行った。
【００３４】
従来の操業期間とこの発明の設計条件（β_6t＜0.05）による操業期間における、前記(1) 式により算出されるβ_6tおよびコークスケーキの押出し不良の経時変化のグラフを図５に示す。
【００３５】
図５から明らかなように、従来の操業では、計算されるβ_6tの平均値が0.089 で、押出し1000回当りの押出し不良発生頻度の平均が25.4回／日であったのに対し、この発明の設計条件による操業では、計算されるβ_6tの平均値が0.029 で、押出し1000回当りの押出し不良発生頻度の平均値が0.6 回／日と大幅に低減している。
【００３６】
これらの結果より、コークスケーキ圧縮中の一定押力に対する側壁荷重の比の炉壁負荷指数（β_6t) を指標としてコークス炉の操業を行うことにより、コークスケーキの押出し性を大幅に改善できることがわかる。
【００３７】
【発明の効果】
この発明は、コークス炉の操業に当り、コークスケーキ圧縮中の一定押力に対する炉壁荷重の比を炉壁負荷指数とし、この炉壁負荷指数を指標として操業するものであり、
この発明によれば、コークスケーキの押止りや押詰りなどの押出し不良、さらには押出不良発生によるコークス炉の損傷を未然に防止でき、炉の寿命延長に大きく貢献できる。
【図面の簡単な説明】
【図１】コークスケーキの圧縮ひずみとβおよび圧縮応力との関係を示すグラフである。
【図２】
【外１０】をパラメーターとするβ_6tとＭＦとの関係のグラフである。
【図３】実機における押出し不良の発生頻度とコークスのタンブラー強度（ＴＩ）との関係のグラフである。
【図４】実機における押出し不良の発生頻度とβ_6tとの関係のグラフである。
【図５】実機における従来の操業期間とこの発明の設計条件による操業期間における、β_6tおよび押出し不良の径時変化のグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention proposes a method of operating a coke oven that improves the extrudability of coke cake.
[0002]
Blast furnace coke functions as a reducing agent, a heat source, and a support material for maintaining air permeability, and it is essential to supply high-quality coke to the blast furnace stably. However, in the early 21st century, most coke ovens in Japan reach the age of 35 years, which is now considered to be the life of coke ovens.Therefore, alternative furnaces for coke ovens are currently being studied by steel companies and others. . For example, a continuous forming coke oven (for example, Okuhara et al .: Iron and Steel, S584-587, 1979) and the like. However, the investment amount of the equipment is enormous in any of the technologies, and at present, the next generation blast furnace coke production technology that can be used 100% as a substitute for the conventional room furnace type coke has not been developed.
[0003]
Therefore, it is debatable that extending the life of the current coke oven is the most important for the current blast furnace ironmaking method. Factors that determine the life of the coke oven include equipment problems such as damage to the brick of the carbonization chamber side wall (hereinafter, furnace wall), deformation of the furnace body such as a backstay, and poor sealing of the door. In particular, it is considered that damage to the furnace wall brick, which cannot be drastically repaired during operation, is fatal. The damage to the brick is not only caused by aging, but also when a load is applied to the furnace wall during coke extrusion and the coke is blocked in the carbonization chamber, making extrusion difficult or impossible (hereinafter referred to as “stopping”, “tightening”, respectively). , In other words, poor extrusion). Further, the damage to the furnace wall easily induces further extrusion failure, so that not only does the cycle of the furnace become vicious, but also the load on the furnace wall is further increased by increasing the proportion of humidified coal or weakly caking coal.
[0004]
[Prior art]
So far, there have been some basic studies on coke extrusion properties (for example, VIAdes et.al: AIME 45th Ironmaking Conference, 1986. p.459). However, no technology for preventing clogging has been obtained.
Further, JP-A-5-339580 (coke oven operating method) and JP-A-6-271865 (coke oven operating method) describe that after the core temperature reaches the re-solidification temperature, or when the expansion pressure is increased. There is disclosed a technique for preventing clogging by controlling the ratio between the amount of burnout in the vertical or horizontal direction after the value becomes 0 and the charging height or the furnace width. However, in these techniques, it is essential to measure the amount of burnout during the coking process for each blended coal, and it is difficult to reflect this in the blending design of the blended coal in daily operation.
[0005]
In addition, there has been no example of examining the extrudability of coke from the viewpoint of the severely damaged furnace wall state and the use of poor coking coal as described above. For this reason, damages to the furnace wall and hearth are detected in advance based on information obtained during operation and repairs are performed to prevent them from being stopped and clogged, and further damage to the furnace wall and hearth is prevented. Prevention techniques are oriented. For example, Japanese Unexamined Patent Publication No. 3-146589 (method for diagnosing abnormalities in the furnace wall of a coke oven carbonization chamber) discloses a technique for diagnosing abnormalities in a furnace wall from load information applied to a motor during extrusion.
[0006]
Repair of the furnace wall of the coking chamber is possible by spraying brick materials such as Si and SiO ₂ , which is actually carried out in actual operation and has a great effect on reducing extrusion defects. Therefore, the technique of performing a thermal spray repair of the damaged part by diagnosing the furnace wall state using the diagnostic method as disclosed above is a significant one, but is a measure after the kiln is damaged to some extent, This is not a fundamental solution to poor extrusion. Furthermore, due to the large number of kilns per furnace group, from several tens to hundreds, this thermal spray repair has a large burden both efficiently and economically.
[0007]
[Problems to be solved by the invention]
In ordinary coke production, it is general to determine the operating conditions of the coke oven, such as coal blending and flue temperature, so as to satisfy the coke performance required when using a blast furnace. The coke performance referred to here includes, for example, particle size, tumbler strength (TI), drum strength (DI), post-reaction strength (CSR), reactivity (JIS-reactivity), and the like. However, since these operating methods do not take coke extrudability into consideration, they do not provide a drastic solution in the case of frequent extrusion failure due to aging or damage of the furnace. In addition, at present, the relationship between the operating conditions and the extrudability of coke has not been clarified, and no operating technology of a coke oven for improving the extrudability of coke has been obtained.
[0008]
In view of these backgrounds, the present invention focuses on the relationship between the structure of coke cake determined under various operating conditions and the extrudability of coke cake for the purpose of developing technology applicable to actual operation. It is an object of the present invention to propose a method of operating a coke oven in which coking cake characteristics and operating conditions are optimized by selecting or adjusting the mixing ratio of the coke oven to prevent the occurrence of coke cake extrusion failure.
[0009]
[Means for Solving the Problems]
The gist of the present invention is as follows.
(1) A coke oven in which coke cake obtained by mixing raw coal or a mixture of two or more kinds of coal into a coke oven carbonization chamber is extruded from a carbonization chamber by an extrusion ram and then carbonized by carbonization by extruding. In the operation method,
The ratio of the side wall load to the constant pressing force during coke cake compression was determined as an oven wall load index by experiment or calculation from the coking coal characteristics and operating conditions, and the coke cake was extruded using the oven wall load index as an index. (A first invention).
[0010]
{Circle around (2)} The furnace wall load index is determined using the coking property of the coking coal and the degree of coalification, and the coking coal is sorted or the mixing ratio is adjusted so that the obtained index value satisfies a predetermined range. The method of operating a coke oven according to the first invention, wherein the method is performed (second invention).
[0011]
(3) The method of operating a coke oven according to the second invention, wherein the maximum fluidity, the total expansion rate or the tackiness index is used as the caking property, and the volatile content, the calorific value or the vitrinite average reflectance is used as the degree of coalification. (Third invention).
[0012]
{Circle around (4)} The method of operating a coke oven according to the first, second or third invention (the fourth invention), wherein the furnace wall load index is represented by the following equation (1) and the index is controlled to a certain value or less. ).
(Equation 2)

[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The operation of the present invention will be described in detail below.
In normal coke oven operation, coke cake is pushed from one side (machine side) by an extrusion ram and discharged. At this time, if the pushing force exceeds the maximum permissible value determined for the capability of the extruder and the furnace wall protection, it is a poor extrusion that the extrusion is electrically interrupted or stopped. As a result of observing the extrusion of the coke cake in the actual machine from the coking coal charging hole, when a pushing force was given by the extrusion ram, the coke cake was extruded while expanding in the horizontal direction (furnace wall direction). It became clear that when it became remarkable, it resulted in poor extrusion. This is because, when a load is applied to the furnace wall due to the lateral spread during the extrusion of the coke cake, the thrust for discharging the coke cake is reduced by friction with the wall surface. That is, if the ratio of the furnace wall load to the pressing force (hereinafter referred to as β) exceeds a certain value, the thrust required for extruding the coke cake cannot be obtained even if the pressing force reaches its maximum allowable value, leading to poor extrusion. it is conceivable that.
[0014]
The present invention has been achieved based on these findings, and the details thereof will be described below.
In a coal carbonization test furnace that eliminates the constraint between the furnace wall on one side and the furnace body and allows the load on the furnace wall to be measured when the coke cake is compressed by the extrusion ram, the pushing force of the extrusion ram and the coke cake compression An experiment was conducted to measure the relationship between the load on the furnace wall and the load.
[0015]
Therefore, as one example of the above experimental results, the compressive strain of the coke cake (the amount of compressive deformation with respect to the length of the coke cake before compression), β (furnace wall load index), and the compressive stress (the pressing force during compression) were converted into stress values. Is shown in FIG.
[0016]
As can be seen from FIG. 1, the deformation of the coke cake increases in accordance with the increase in the amount of deformation (compression strain) in the compression direction, as indicated by the dotted lines in FIG. The first region where the resistance is small and stable, the second region where the deformation resistance starts to rise, β occurs, the third region where the value is stable, and the fourth region where the deformation resistance and particularly β rapidly increase. It can be seen that when the deformation amount (compression strain) of the coke cake exceeds a certain value, the deformation resistance (compression stress) and β rapidly increase.
When the amount of deformation of the coke cake enters the region where β is rapidly increased, the probability of occurrence of extrusion failure increases.
[0017]
Therefore, as a result of conducting experiments under various conditions, it was found that the compressive stress at the boundary of the β rapid increase region was almost constant irrespective of the blending of the coking coal (coking coal characteristics) and the operating conditions. From this, the region where the deformation of the coke cake rapidly increases β, in this case, the ratio of the furnace wall load to the pressing force at the pressing force of 6 t (hereinafter referred to as β _6t ) is an index indicating the extrudability of the coke cake. There was found.
[0018]
Furthermore, as a result of repeated experiments, it was found that β _6t has a strong relationship with the properties of coking coal (caking properties, degree of coalification, moisture, etc.), coking coal properties such as carbonization time and flue temperature, and operating conditions. .
[0019]
Generally, β _6t can be given by the following equation (2).
β _6t = f (P _1, P ₂ , P ₃ ---) --- (2)
Here, P _i is the coking coal characteristics (caking property, coal degree, water), dry distillation time, flues temperature, coking coal properties and operating conditions, such as bulk density and particle size.
[0020]
For example, β _6t is the maximum fluidity (hereinafter, referred to as MF) of the coking coal, the degree of coalification (hereinafter, vitrinite average reflectance:
[Outside 1]

) And decreases with the increase in MF and

Is generally given by the following equation (3).
[Equation 3]

Here, a _c , b _c , c _c , d _c and e _c are constants determined from other operating conditions.
[0021]
In the above, when a plurality of coals having different maximum fluidity and coalification degree are blended and used as raw coal, MF, which is load averaged based on the blending ratio thereof,
[Outside 3]

May be used as a representative value.
[0022]
Then, based on the experimental results, in the case of flue temperature: 1000 ° C., dry distillation time: 18 hours, and raw coal water content: 6%.

FIG. 2 shows a graph of the relationship between β _6t and MF, with as a parameter.
[0023]
As apparent from FIG. 2, the furnace wall load during the coke cake compression was determined by the coking coal MF,
[Outside 5]

Decreases in this case, where β _6t is MF and

The following equation (1) can be obtained as a function of
(Equation 4)

[0024]
Further, the relationship between the carbonization time: t and β _6t is generally given by the following equation (4).
_{β 6t = a t (t-} b t) 2 + c t --- (4)
Here, a _t, b _t and c _t are constants determined from other coking coal characteristics and operating conditions.
[0025]
For other coking coal characteristics and operating conditions, such as the water content, bulk density, particle size, and flue temperature of the coking coal, a general relational expression with β _6t similar to the above can be obtained. A combination of these relations to each other by using the above equation (2), beta _6t is obtained in various conditions, it is possible to predict the extrudability of the coke cake by the beta _6t, and the index of this beta _6t By doing so, poor extrusion of the coke cake can be prevented.
[0026]
Next, in the operation of the actual coke oven, the relationship between the coking coal characteristics and the operating conditions and the extrudability of the coke cake was investigated. The target coke oven has a furnace height of 6.4 m, a furnace width of 430 mm, and a depth of 14.8 m, and is a 66 furnace group. Since the furnace order of this furnace group is as young as about 17 years, there is almost no damage to the furnace wall. The survey period is one year, and the coking coal characteristics and operating conditions during the survey period are as follows:
[Outside 7]

= 0.87 to 1.14, MF = 1.82 to 2.98, raw coal moisture: 5.5 to 7.5%, furnace temperature: 1150 to 1250 ° C, and operation rate (number of extrusions per kiln per day x 100): 130 to 150%. The extrudability was evaluated as the total number of defective extrusions per day in all kilns. FIG. 3 is a graph showing the relationship between the frequency of occurrence of the extrusion failure and the tumbler strength of coke: TI. FIG. 3 shows the relationship between the frequency of the occurrence of the extrusion failure, the characteristics of the raw coal and the operating conditions, and β _6t obtained by the above equation (1). A graph of the relationship is shown in FIG.
[0027]
As is clear from these figures, there is no correlation between the TI (tumbler strength) of coke and the frequency of occurrence of poor extrusion, and as the coke strength increases, the poor extrusion results as previously thought. It turns out that it cannot be said that it decreases. On the other hand, for β _6t , a clear correlation is seen between the occurrence frequency of the extrusion failure and the threshold value at which the extrusion failure does not occur. The threshold value in this case is β _6t = 0.05, but this threshold value changes depending on conditions such as the size of the coke oven and the degree of damage.
[0028]
In addition, an experiment was conducted to investigate the effect of blending of raw coal on coke extrudability in an actual coke oven different from the above (91 gates, oven height: 5.9 m, oven width: 460 mm, depth: 14.9 m). Each experiment was carried out under the same operating conditions except for the blending of the raw coal for 50 kilns, and the above equation (1) was used to calculate _β6t . Formulation of raw material coal is 10 levels of 0.01 to 0.1 in beta _6t, beta _6t is MF in formulation 0.05 0.06,
[Outside 8]

Was changed by five levels. Table 1 shows the results of these experiments.
[0029]
[Table 1]

[0030]
In this case as well, it was found that coke extrusion failure could be prevented by the coking coal characteristics and operating conditions _satisfying β _6t ≦ 0.05.
These results, as have the same extrudability, if other than beta _6t is small for coke cake obtained from raw coal characteristics and operating conditions comprising beta _6t is the same as calculated from equation (1) Extrusion It was found that the extrudability improved because the effective thrust increased.
[0031]
On the other hand, as a result of investigating the relationship between the furnace wall load generated during the extrusion of the coke cake and the internal structure of the coke cake, it was found that the crack structure in the cake greatly affected the furnace wall load during the extrusion. Furthermore, the relationship between the coal blend and the crack structure in the cake was investigated, and it was found that the properties of the raw coal and the operating conditions dominated the crack structure related to the occurrence of furnace wall load. For example, the structure in the coke cake changes due to the increase in the coking property and the degree of coalification of the raw coal, and the movement in the cake that generates a furnace wall load is suppressed.
In the case of the above equation (1), MF is used as an index representing the cohesiveness of the raw coal, and an index representing the degree of coalification is expressed as follows.

However, in the present invention, for example, the total expansion coefficient, an index of adhesiveness, etc., as an index indicating the caking property, an index indicating the degree of coalification, such as a volatile content, a calorific value, etc., may be used. Even if it is used, there is no essential difference, only the calculation formula constituting the management index is different.
[0032]
In general, causes of poor extrusion of coke cake include aging of the furnace, adhesion of carbon to the furnace wall and ceiling, damage to the furnace wall, and the like. However, by using the present invention to properly design coking coal characteristics and operating conditions and adopting a coke cake structure that suppresses the furnace wall load generated during extrusion, the occurrence of poor extrusion can be achieved even under the above factors. Can be prevented. That is, by calculating the furnace wall load index, which indicates the furnace wall load during coke extrusion, from the coking coal characteristics and the operating conditions, and designing the coking coal and the operation so as not to exceed this threshold, the coke cake discharge is performed. In this case, it is possible to ensure the extrudability at the time, and prevent the occurrence of defective extrusion and further prevent the coke oven from being damaged due to the defective extrusion.
[0033]
【Example】
In an actual coke oven (91 gates, furnace height: 5.9 m, furnace width: 460 mm, depth: 14.9 m), an operation test using a design according to the present invention was conducted for three months, and a comparison with a conventional operation was performed.
[0034]
FIG. 5 is a graph showing the change over time of β _{6 t} calculated according to the above equation (1) and poor coke cake extrusion during the conventional operation period and the operation period according to the design conditions (β _6t <0.05) of the present invention.
[0035]
As is clear from FIG. 5, in the conventional operation, the average value of β _6t calculated was 0.089, and the average frequency of occurrence of poor extrusion per 1000 extrusion operations was 25.4 operations / day. In the operation under the design conditions, the average value of the calculated β _6t is 0.029, and the average value of the frequency of defective extrusion per 1,000 extrusions is significantly reduced to 0.6 times / day.
[0036]
From these results, it is found that the extrudability of coke cake can be significantly improved by operating the coke oven using the furnace wall load index (β _6t ), which is the ratio of side wall load to constant pressing force during coke cake compression, as an index. Understand.
[0037]
【The invention's effect】
The present invention relates to the operation of a coke oven, in which the ratio of the oven wall load to the constant pressing force during coke cake compression is used as the oven wall load index, and the operation is performed using the oven wall load index as an index.
ADVANTAGE OF THE INVENTION According to this invention, the coke oven can be prevented from being pushed out of the coke cake, such as improper pushing or clogging, and furthermore, the coke oven can be prevented from being damaged due to improper extruding, and can greatly contribute to extending the life of the coke oven.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between compressive strain, β and compressive stress of a coke cake.
FIG. 2
10 is a graph showing the relationship between β _6t and MF using 【as a parameter.
FIG. 3 is a graph showing the relationship between the frequency of occurrence of extrusion failure and the tumbler strength (TI) of coke in an actual machine.
FIG. 4 is a graph showing the relationship between the frequency of occurrence of extrusion failure and β _{6t in} an actual machine.
FIG. 5 is a graph showing changes in β _6t and extrusion failure over time during a conventional operation period in an actual machine and an operation period according to the design conditions of the present invention.

Claims (4)

A method of operating a coke oven in which coke cake mixed with plain or two or more types of coal is charged into a coke oven carbonization chamber, and then the coke cake carbonized by dry distillation is extruded from the carbonization chamber by an extrusion ram and discharged. ,
The ratio of the side wall load to the constant pressing force during coke cake compression is determined as the furnace wall load index by experiment or calculation from the coking coal characteristics and operating conditions, and the coke cake is extruded using the furnace wall load index as an index. A method of operating a coke oven characterized by ensuring the following. The furnace wall load index is determined by using the coking property of the coking coal characteristic and the degree of coalification, and the coking coal is selected or the mixing ratio is adjusted so that the obtained index value satisfies a predetermined range. The method for operating a coke oven according to claim 1, wherein: The method for operating a coke oven according to claim 2, wherein the maximum fluidity, the total expansion rate or the tackiness index is used as the caking property, and the volatile content, the calorific value, or the vitrinite average reflectance is used as the coalification degree. The method of operating a coke oven according to claim 1, 2, or 3, wherein the furnace wall load index is represented by the following equation (1), and the index is controlled to a certain value or less.

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