JP3551487B2 - Bulk density management method for coke oven charging coal - Google Patents

Description

上式に基づいて平均付着水分Ｍ_Ｓ を一定にして低品位炭の配合率を変化させた場合の装入炭の全水分の変化を表す模式図を図４に示す。粉粒体特性を変えずに、低品位炭の配合率を増加させるには低品位炭の配合率に応じて全水分の制御値を高くしなければならない。
【００２３】
以上のように、石炭配合から平均包蔵水分が決まって、粉体特性から平均付着水分を設定することによって制御可能な全水分が決定される。本水分制御方法では、従来と同じ石炭調湿設備の全水分制御を行うだけで嵩密度などの粉体特性を装入炭の配合の変動に応じて制御可能である。
【００２４】
【実施例】
以下、本発明を実施例に基づいて説明する。
（実施例−１）
表１に示す石炭Ｄ、Ｃをそれぞれ単独及びＤ：Ｃ＝２５：７５及び５０：５０の比率で混炭し全水分と嵩密度との関係を調べたところ図５の結果を得た。これらを全水分と包蔵水分から得られた付着水分で整理したところ、図１を得た。図１と図５との対比から付着水分によって嵩密度をばらつき少なく管理することができると結論づけられる。包蔵水分の多い石炭を用いるときには特に顕著であることがわかる。
【００２５】
（包蔵水分の測定）
本実施例と比較例に用いた石炭を第１表に示す。各石炭の包蔵水分の測定は粒度を１．１９ｍｍ以下としてＪＩＳ Ｍ８８０３の方法に従って行った。また各石炭の包蔵水分の測定結果を表１に示す。
【００２６】
【表１】

【００２７】
石炭化度を表わす平均反射率Ｒ_Ｏ と包蔵水分の関係を図３に示す。Ｒ_Ｏ の増加に従って包蔵水分は低下しており、平均反射率Ｒ_Ｏ と包蔵水分は強い相関があるる。
（嵩密度測定に用いた試料の粒度と水分の調整）
嵩密度の測定には、各銘柄の石炭の粒度分布を一定にする目的で、＃０．５，１．０，２．０，２．８２ｍｍの篩で０．５ｍｍ以下，０．５〜１．０ｍｍ，１．０〜２．０ｍｍ，２．０〜２．８２ｍｍの各粒度の重量比率が２５％となるように調製した石炭を用いた。石炭の水分調整は粒度調整した石炭に水を添加、混練後、全水分を測定して、全水分を確認した。
【００２８】
（嵩密度測定）
粒度調整、水分調整を行った石炭５００ｇを１０００ｍｌのメスシリンダーに装填後、振動発生器上に３０秒置いて、充填した。その体積と重量から嵩密度を得た。
（実施例−２）
配合炭において全水分を約６％とし、包蔵水分の多いＣ炭の配合量を増加した場合の嵩密度について、実施例および比較例を表２に示す。
【００２９】
実施例１は、嵩密度の目標値を０．７７５とし、平均付着水分を２．９１とした。比較例１，２は包蔵水分の多いＣ炭を増加した。このとき全水分を一定に約６．０％にすると、嵩密度は０．７８および０．８０に増加し、全水分では嵩密度を管理することはできなかった。そこで表２の実施例２、３のようにＣ炭の配合量を増加した配合炭について、付着水分が一定値２．９になるように包蔵水分の増加に応じて全水分を制御したところ、嵩密度は目標嵩密度に一致する０．７７５になった。
【００３０】
【表２】

【００３１】
【発明の効果】
コークス炉前での従来の画一的な全水分制御では日々変動する石炭配合に応じてコークス炉装入炭の密度を制御することは困難である。本発明では石炭の銘柄毎、炭種毎の水分特性を考慮した平均付着水分の調整を行い、石炭配合の変動に応じた嵩密度の管理が可能となり、生産性の向上に優れた効果を奏する。
【図面の簡単な説明】
【図１】石炭の付着水分と嵩密度との関係を示すグラフである。
【図２】包蔵水分と測定温度の関係を表わす模式図である。
【図３】石炭の平均反射率Ｒ_Ｏ と包蔵水分との関係を示すグラフである。
【図４】平均付着水分Ｍ_Ｓ を一定にして、低品位炭の配合率を変化させた場合の装入炭の全水分の変化を表す模式図である。
【図５】石炭の全水分と嵩密度との関係グラフである。
【符号の説明】
Ｍ_Ａ 全水分
Ｍ_Ｓ 付着水分
Ｍ_Ｅ 包蔵水分
Ｒ_Ｏ 石炭の平均反射率[0001]
[Industrial applications]
The present invention relates to a method for managing the bulk density of coal charged in a coke oven when producing coke for metallurgy. More specifically, a method of managing the bulk density of coke oven charged coal in which the embedded moisture of charged coal is estimated from the stored moisture of each brand of coal and the moisture is adjusted so that the bulk density of the coke oven charged coal becomes a predetermined value. About.
[0002]
[Prior art]
In the operation of a coke oven, it is desirable that the water content of the charged coal be low from the viewpoint of the amount of carbonization heat. However, if the water content of the charged coal is extremely low, dust is generated when the charged coal is charged into the coke oven, which is a problem in environmental management.
In addition, the bulk density of the charged coal charged into the coke oven is affected by the attached moisture of the charged coal, and when the charged coal fluctuates, the moisture adhering to the surface of the charged coal generally varies. Therefore, the characteristics of the granular material change greatly, and the bulk density of the charged coal when charged into the coke oven changes. As a result, the coke quality may fluctuate, and in extreme cases, so-called compaction may be caused, which makes it difficult to extrude coke from a coke oven.
[0003]
As a method for solving such a problem, for example, JP-A-61-163988 discloses a method of measuring the particle size and moisture of undried charged coal, and using the measured values as a factor to determine the carbonization conditions and / or charging specifications. A method of controlling is disclosed. Such a method is realized by introducing a charged coal humidity control equipment before the coke oven.However, since the contained moisture differs depending on the blending ratio of each brand coal constituting the charged coal, the same total moisture cannot be obtained. In addition, the adhering water changes greatly due to the change in the blending of the brand coal, and therefore the bulk density of the charging coal changes in the setting of the charging specifications corresponding to the same total water. It was not a solution.
[0004]
This becomes a more serious problem when a large amount of low-grade coal such as finely caking coal is blended into the coal which has recently become particularly important.
That is, when a large amount of low-grade coal such as slightly caking coal is blended into the charged coal, the bulk density fluctuates because the contained moisture and the attached moisture are greatly different even with the same total moisture. This is because the inventors have found out.
[0005]
That is, in the case of strong caking coal, which is the main raw material of ordinary charged coal, the contained moisture (equilibrium moisture, see JIS M8803) is 1 to 2%, whereas that of low-rank coal such as fine caking coal is 3 to 2%. It is as high as about 10%, and when these are blended, the average stored moisture of the charged coal fluctuates greatly, and when the total moisture is controlled to be constant, the average attached moisture also fluctuates, and as a result, the bulk density of the charged coal fluctuates.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to solve the above problems, that is, as represented by a case where a large amount of low-grade coal such as finely caking coal is blended into the charged coal, Even if the total water content of the coal is constant, the stored moisture and the attached moisture greatly change depending on the blending ratio of each brand coal constituting the charged coal, which may have an adverse effect on the product quality. Even in such a case, the bulk density of the coke oven charged coal is controlled by controlling the moisture content of the charged coal so that the variation in the quality of the product coke is substantially minimized. It provides a method.
[0007]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems, and adjusts the average attached moisture of the charged coal according to the target bulk density of the charged coal in the coke oven. It is a management method. In this case, using the M _S follows the average adhesive moisture instrumentation Nyusumi to adjust the total water content M _A of instrumentation Nyusumi, it is also possible to adjust the average adhesive moisture instrumentation Nyusumi.
[0008]
_{M S} = M A -M _E
Here, M _{A is} the total water content M _{E of the} charged coal M _E = fi · wi
fi: the blending ratio of each brand coal wi: the stored moisture of each brand coal. The stored moisture of coal is the moisture (%) contained in a coal sample when the sample is brought to a constant temperature equilibrium in an atmosphere of 96 to 97% relative humidity.
[0009]
Further, instead of the said M _E, may be used for the next M _{E '.}
M _E ′ = Σfi · g (ai)
Here, g (ai) is a value of a functional regression equation wi = g (ai) obtained from the physical property value ai corresponding to the stored moisture wi of coal. As such a physical property value ai, for example, a degree of coalification, a specific surface area, a carbon content, or the like can be used.
[0010]
[Action]
FIG. 5 shows the results of measuring the bulk density of the blended coal by adjusting the total moisture by changing the blending ratio of two types of coal having different stored moisture. In FIG. 5, D is strong caking coal having a small amount of stored moisture, and C is fine caking coal having a large amount of stored moisture. The relationship between the total moisture and the bulk density in FIG. 5 shows that the bulk density tends to decrease as the total moisture increases, but is affected by the type of coal and its blending ratio. Therefore, it was found that the bulk density could not be controlled even if the total water content was controlled to be constant.
[0011]
Then, when the relationship between the attached moisture and the bulk density was determined, the result of FIG. 1 was obtained. Based on this result, the present invention is characterized in that the average attached moisture of the charged coal is adjusted according to the target bulk density of the charged coal in the coke oven.
The average attached moisture is controlled in consideration of the characteristics of the granular material of the charged coal. For example, based on the relationship between the attached moisture and the bulk density as shown in FIG. 1, the average attached moisture may be determined for the target bulk density in consideration of coke quality or coke oven operation. As is clear from FIG. 1, the bulk density has a strong correlation with the amount of attached moisture regardless of the type of coal. Therefore, the intended purpose can be achieved by adjusting the average attached moisture of the charged coal according to the target bulk density of the charged coke oven coal.
[0012]
By the way, it is not easy to directly and directly measure the moisture adhering to the coal charged in a coke oven on site. Therefore, the present inventors estimated the attached moisture from the total moisture of the coal coal which is easy to measure and the embedded moisture which is a fixed value of the brand coal, and used this value to determine the bulk density of the coal charged to the coke oven. After confirming that it can be managed, the second invention of the present invention has been completed. Strong caking coal is indispensable for the production of metallurgical coke. Increasing the ratio of inexpensive non-coking coal and fine caking coal is effective in reducing coke production costs.
[0013]
However, the moisture content of low-rank coal such as slightly caking coal is significantly different from that of strong caking coal.
The moisture content of each brand coal constituting the coke oven charging coal is categorized into the contained moisture contained inside the brand coal and the surface attached moisture attached to the brand coal surface as shown below,
M _A (total moisture) = _{M E} (occluded water) + _{M S} (adhering moisture)
There is a relationship.
[0014]
In general, low-grade coal contains more moisture than strong caking coal. Therefore, when comparing low-grade coal and strong-coking coal with the same total moisture, low-grade coal has a large amount of embedded moisture, so the amount of water adhering to the surface of the brand coal is lower than that of strong-coking coal. However, even if they are the same, the powder properties of low-grade coal and strongly caking coal will be different.
In the coke oven charging coal, when the blending ratio of each brand coal changes, especially when the low-rank coal is added and blended, the low-rank coal has a large amount of stored moisture, so the average stored moisture of the charged coal increases. If the total water content is controlled to a certain level and the blending ratio of low-grade coal in the charged coal is increased, the total amount of moisture stored in the charged coal increases, and the total amount of moisture adhering to the surface of the charged coal decreases. Will be. Therefore, the average adhering moisture is reduced, and as a result, the charging parameters related to the powder characteristics such as the bulk density when charging the charged coal into the coke oven are changed.
[0015]
Therefore, in order to control the moisture content of the coke oven charging coal, that is, to control the charging specifications paying attention to the powder characteristics, it is necessary to adjust the adhesion moisture of the charging coal.
However, even if there is a coal humidity control facility, it is difficult to separate and measure the stored moisture and attached moisture in front of the coke oven. That is, the analysis of the stored moisture takes a considerable amount of time, so that individual control of the attached moisture is impossible.
[0016]
In view of these points, the inventors of the present invention evaluate in advance the contained moisture, which is a characteristic characteristic of coal brands, and in consideration of this, control the total moisture that can be easily measured and monitored. A wide range of experimental studies was conducted based on the idea that the amount of adhering water could be adjusted. In addition, if the stored moisture was accurately associated with other characteristic values of the coal, various studies were conducted on the possibility of controlling the surface adhesion moisture by evaluating them in advance, and the following findings were obtained. .
(1) The stored moisture is related to fine pores in the coal structure, and is considered to be equilibrium moisture adsorbed on the pore inner surface.
(2) Therefore, if the degree of coalification is different, the stored moisture is greatly different, and if the degree of coalification is the same, the stored moisture takes substantially the same value.
(3) The water content of coal is represented by (total water content) = (adhered water content) + (covered water content). The stored water content is a value that changes depending on the temperature and the atmospheric humidity, but the temperature and humidity measurement conditions change. Even so, the relationship of (total moisture) = (adhered moisture) + (stored moisture) holds. Also, coal containing more moisture requires more heat energy to evaporate the moisture. When the coal temperature at the time of charging coal is equal to or higher than room temperature, the stored moisture at that time changes, but the magnitude relationship between the coal types of the stored moisture does not change. For example, the stored moisture of the i coal type and the j coal type is not changed. The ratio is almost constant even when the measured temperature is changed, as shown in FIG.
(4) When the charging coal is formed by blending various kinds of brand coals, the stored moisture of the charging coal is the sum of the stored moisture of each blended brand coal. That is, the stored moisture of the charged coal is obtained by the arithmetic mean.
[0017]
Based on these findings, the second and third inventions of the present invention were created.
That is, the stored moisture is obtained in advance as a pre-measured value for each brand of charged coal, or is obtained in advance from a regression equation representing the stored moisture associated with a characteristic value such as the degree of coalification for each brand. By estimating the moisture content of the charged coal from the blending brand and the blending ratio of the charged coal, and adjusting the total moisture with the coal humidity control equipment so that the total moisture is obtained by adding the target adhesion moisture to this. This is a method based on the basic technical idea of indirectly adjusting the amount of adhering water which is difficult to measure in front of a coke oven.
[0018]
If the average attached moisture is set to a certain value in consideration of the powder characteristics of the charged coal, the total moisture that can be managed in front of the coke oven is determined as follows.
That is, in the present invention, the stored moisture of coal of each brand used for charging coal is measured and obtained in advance, and the average stored moisture of the charged coal is determined from the mixing ratio of each brand. Further, as shown in FIG. 3, a regression equation is previously obtained from a graph showing the relationship between the average reflectance R _O representing the degree of coalification of the coal of each type of coal and the contained moisture, and the regression equation for each type of coal i having the degree of coalification R _Oi It is also possible to obtain the calculated value of the stored moisture and obtain the stored water of the charged coal as an arithmetic sum over those types of coal.
[0019]
That is, in the present invention, (a) the brand of the charged coal and its blending ratio, and (b) other parameters having a strong correlation with the stored moisture may be used as the parameters corresponding to the stored moisture. The average reflectance R _O and its compounding ratio were used. It is possible to control the attached moisture using these parameters according to the concept of the present invention.
[0020]
For example, the average occluded moisture M _E from the occluded moisture obtained for each coal stocks blending ratio instrumentation Nyusumi is obtained by the following equation.
Average stored water M _E = Σfi · wi
fi: i coal type of mixture ratio wi: i coal species occluded moisture also mean embryonated moisture from occluded moisture obtained for each coal type and its coal species mixture ratio instrumentation Nyusumi M _E is obtained by the following formula .
[0021]
Average stored water M _E = Σf ' _i · g (R _Oi )
R _Oi : coalification degree parameter R ₀ of i coal type
g (R _Oi ): A function regression equation f ′ _i representing the contained moisture of the i coal type f ′ _i : The adhering moisture is set to a certain control value for the purpose of controlling the blending ratio of the i coal type and the powder characteristics of the charged coal. if it can control the average adhesive moisture M _S by controlling the total water M _a of Sonyusumi as: coal type stocks, constant regardless of the mixing ratio.
[0022]

The schematic diagram showing the change in total moisture instrumentation Nyusumi when a by the average moisture adheres M _S based on the above equation the constant changing the blending ratio of low-grade coal is shown in Fig. In order to increase the blending ratio of low-grade coal without changing the properties of the granular material, the control value of the total moisture must be increased in accordance with the blending ratio of low-grade coal.
[0023]
As described above, the average stored moisture is determined from the coal blend, and the total moisture that can be controlled by setting the average attached moisture from the powder characteristics is determined. In the present moisture control method, powder characteristics such as bulk density can be controlled according to the change in the blending of the charged coal only by controlling the total moisture of the coal humidity control equipment as in the related art.
[0024]
【Example】
Hereinafter, the present invention will be described based on examples.
(Example-1)
When the coals D and C shown in Table 1 were mixed alone and in a ratio of D: C = 25: 75 and 50:50, and the relationship between the total moisture and the bulk density was examined, the results shown in FIG. 5 were obtained. Fig. 1 was obtained by arranging these by the attached moisture obtained from the total moisture and the stored moisture. It can be concluded from the comparison between FIG. 1 and FIG. 5 that the bulk density can be controlled with less variation by the attached moisture. It turns out that it is particularly remarkable when coal containing a large amount of stored moisture is used.
[0025]
(Measurement of stored moisture)
Table 1 shows the coal used in this example and the comparative example. The measurement of the moisture content of each coal was performed according to the method of JIS M8803 with a particle size of 1.19 mm or less. Table 1 shows the measurement results of the moisture content of each coal.
[0026]
[Table 1]

[0027]
The relationship between the average reflectance R _O and occluded water representing the coal degree shown in FIG. Occluded water with increasing R _O has declined, the average reflectance R _O and embryonated moisture strong correlation Arles.
(Adjustment of particle size and moisture of sample used for bulk density measurement)
The bulk density was measured using a # 0.5, 1.0, 2.0, or 2.82 mm sieve with a size of 0.5 mm or less and 0.5 to 1 in order to keep the particle size distribution of each brand of coal constant. Coal prepared such that the weight ratio of each particle size of 0.0 mm, 1.0 to 2.0 mm, and 2.0 to 2.82 mm was 25% was used. The water content of the coal was adjusted by adding water to the coal whose particle size was adjusted, kneading, measuring the total water content, and confirming the total water content.
[0028]
(Bulk density measurement)
After 500 g of coal having been subjected to particle size adjustment and moisture adjustment was charged into a 1000 ml measuring cylinder, it was placed on a vibration generator for 30 seconds and charged. The bulk density was obtained from the volume and weight.
(Example-2)
Table 2 shows examples and comparative examples of the bulk density in the case where the total amount of moisture is about 6% in the blended coal and the blending amount of the coal C having a large amount of stored moisture is increased.
[0029]
In Example 1, the target value of the bulk density was set to 0.775, and the average attached moisture was set to 2.91. Comparative Examples 1 and 2 increased the amount of C coal having a large amount of stored moisture. At this time, when the total water content was fixed at about 6.0%, the bulk density increased to 0.78 and 0.80, and the bulk density could not be controlled with the total water content. Therefore, for the blended coal in which the blending amount of the C coal was increased as in Examples 2 and 3 in Table 2, the total moisture was controlled according to the increase in the contained moisture so that the attached moisture became a constant value of 2.9. The bulk density was 0.775, which corresponds to the target bulk density.
[0030]
[Table 2]

[0031]
【The invention's effect】
It is difficult to control the density of the coal charged in the coke oven according to the coal blend that fluctuates daily with the conventional uniform moisture control before the coke oven. In the present invention, the average adhesion moisture is adjusted in consideration of the moisture characteristics of each brand of coal and each type of coal, and the bulk density can be controlled in accordance with the variation of the blending of the coal, thereby achieving an excellent effect of improving productivity. .
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the moisture content and the bulk density of coal.
FIG. 2 is a schematic diagram showing a relationship between stored moisture and a measurement temperature.
3 is a graph showing the relationship between the average reflectance R _O and embryonated moisture coal.
[4] by a constant average adhesion moisture M _S, it is a schematic diagram showing the change in total moisture instrumentation Nyusumi in the case of varying the blending ratio of low grade coal.
FIG. 5 is a graph showing the relationship between the total moisture and the bulk density of coal.
[Explanation of symbols]
M _A Total moisture M _S Adhered moisture M _E Stored moisture
Average reflectance of _RO coal

Claims (3)

A bulk density management method for coke oven charging, comprising adjusting the average attached moisture of the charging coal according to a target bulk density of the coke oven charging coal. As average adhesive moisture instrumentation Nyusumi, using M _S of the formula, by variations in the coal blend of instrumentation Nyusumi, in accordance with the average occluded moisture M _E varying, so that the average adhesive moisture M _S to a target bulk density management method coke RoSo Nyusumi of claim 1, wherein the adjusting the total moisture content M _a of instrumentation Nyusumi.
_{M S} = M A -M _E
Here, M _{A is} the total water content M _{E of the} charged coal M _E = fi · wi
fi: blending ratio of each brand coal wi: moisture contained in each brand coal The place of the M _E, bulk density management method coke RoSo Nyusumi according to claim 2, characterized by using the following M _{E '.}
M _E ′ = Σfi · g (ai)
Here, g (ai) is a value of a functional regression equation wi = g (ai) obtained from the physical property value ai corresponding to the stored moisture wi of each brand coal.

Images