Method for producing coal cake for coke production

Abstract

To propose a method for producing a coal cake for coke production that can prevent an inlet-side end of the coal cake from collapsing even when molding the coal cake into blocks by the stamp charging technique.SOLUTION: The present invention provides a method for producing a coal cake for coke production, which molds a coal cake used in coke production by the stamp charging technique. Molding energy at an inlet-side end of the coal cake should be equal to or more than the energy Et (kJ / t) needed to achieve the target density.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a coal cake for coke production, in which a coal cake to be used in coke production is molded by a stamp charge method. [Background technology]

[0002] As high-quality, highly coking coal for use in coke production is becoming scarce, there is a need to ensure strength even when using inferior coal. One technique for improving strength is to increase the bulk density of the coal charged into a coke oven, and one example is the stamp charge method (Patent Document 1).

[0003] In the stamp charge method disclosed in Patent Document 1, a mixture of powdered coal and briquettes is stamped from above with a stamper to form a block-shaped coal cake with high bulk density. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-44126 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the strength of block-shaped coal cakes formed using the stamp charge method varies depending on the location, and as the horizontal distance from the stamper increases, the impact of stamping attenuates, resulting in a lower bulk density and lower strength. Therefore, in coal cakes formed into block shapes by stamping a certain number of times, the inlet end of the coal cake facing the coke oven chamber may collapse due to insufficient strength. In such cases, the coal cake with the collapsed inlet end cannot be charged into the coke oven chamber, and the coal cake cannot be carbonized to produce coke.

[0006] An object of the present invention is to solve the above problems and to propose a method for manufacturing a coal cake for coke production, which can prevent the coal cake from collapsing from the inlet end even when the coal cake is molded into a block shape by the stamp charge method. [Means for solving the problem]

[0007] To prevent the coal cake from collapsing, the density of the coal cake formed by the stamp charge method is 1100 kg / m 3 Therefore, in order to solve the above-mentioned problems, the present invention has conducted extensive research into the causes of the coal cake collapsing from the inlet end, and has obtained the following findings. 1) The closer the coal cake is to the inlet end toward the furnace top, the less energy is transferred from the stamper located in the center. As a result, the coal cake strength is insufficient near the inlet end compared to the center of the coal cake. 2) The density of the resulting coal cake varies greatly depending on the brand, properties, particle size, etc. of the coal, even when the same stamping energy is applied.

[0008] The present invention was made based on the above findings, and its gist is as follows: That is, the present invention provides a method for producing a coal cake for coke production, which comprises molding a coal cake to be used in coke production by a stamp charge method, characterized in that the molding energy at the inlet end of the coal cake is equal to or greater than the energy Et (kJ / t) required to achieve a target density.

[0009] In the method for producing coal cake for coke production according to the present invention configured as described above, (1) The above Et is calculated for each coal based on the stamping energy E (kJ / t) and coal cake density ρ (kg / m 3 ) and be set based on a correlation with (2) The Et satisfies the following formula (1) at any height of the coal cake: Et≦ΣEi / (a×Li+b)···(1) where: Ei: Stamping energy transferred from the i-th stamper to the inlet end of the coal cake (kJ / t); Li: distance to the end of the i-th stamper in the direction of the furnace top (m), a, b: Coefficients determined for each coal. (3) Adjusting the stamping energy E1 of the stamper closest to the inlet end in the Ei; This is considered to be a more preferable solution. [Effects of the Invention]

[0010] According to the method for producing a coal cake for coke production of the present invention, the briquetting energy at the inlet end of the coal cake is equal to or greater than the energy Et (kJ / t) required to achieve a target density at any height of the coal cake, thereby preventing the coal cake from collapsing from the inlet end of the coal cake. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an embodiment of a conventionally known coke oven that uses the coal cake of the present invention. [Figure 2] FIG. 1 is a diagram illustrating an embodiment of stamp charge equipment used in producing a coal cake according to the present invention. [Figure 3] 1 is a graph showing an example of the relationship between stamping energy and coal cake density to explain Et in the present invention. [Figure 4] FIG. 1 is a diagram for explaining an example of a distribution of stamping energy, which is composed of stamping energy and a distance from the edge of the cake, in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail the embodiments of the present invention. Note that the following embodiments are intended to exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to that described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope defined in the claims.

[0013] <Coke oven using the coal cake of the present invention> FIG. 1 is a diagram illustrating one embodiment of a conventionally known coke oven that uses the coal cake of the present invention. In the example shown in FIG. 1, the coke oven 1 is a structure (a furnace battery) in which coke chambers 2 into which coal cakes are charged and combustion chambers 3 that heat the coke chambers 2 are alternately arranged. In the coke chambers 2, coal is steam-roasted (carbonized) to produce coke. The produced coke is removed from the coke chambers 2 by opening detachable furnace covers 4 attached to the kiln openings at the front and rear ends of the coke chambers 2 and pushing the coke horizontally using a push-out ram (not shown).

[0014] A heat regenerator 5 is provided integrally at the bottom of the combustion chamber 3, and the combustion chamber 3 and heat regenerator 5 combust fuel gas 6 with air 9 and discharge the combustion exhaust gas 7 outside the coke oven 1, thereby heating the adjacent carbonization chamber 2 to a temperature at which coal can be carbonized. The coke oven 1 configured as described above has a high coal processing capacity, good thermal efficiency, and can produce high-strength coke.

[0015] In the coke oven 1 having the configuration shown in Fig. 1, the combustion chamber 3 and the regenerator 5 are divided into two longitudinal sections, a combustion side and a withdrawal side, by a partition wall 8, as shown in Fig. 1, and the fuel gas 6 and the burned combustion gas are circulated as shown by the arrows in Fig. 1 from (combustion side of regenerator 5) → (combustion side of combustion chamber 3) → (withdrawal side of combustion chamber 3) → (withdrawal side of regenerator 5), heating the adjacent coke oven 2 to a temperature for carbonizing coal, for example, about 1100°C. After this state continues for about 20 to 30 minutes, the gas flow is reversed to switch between combustion and exhaust, and the combustion side and the withdrawal side are alternately heated and repeated.

[0016] <Method of manufacturing coal cake for coke production according to the present invention> FIG. 2 is a diagram illustrating one embodiment of the stamp charge equipment used to produce a coal cake according to the present invention. In the example shown in FIG. 2, multiple stampers 22 are provided on top of a coal extruder 21. Coal 23 is charged into the coal extruder 21 from above via a hopper 25, and the stamper 22 is moved up and down to stamp the coal 23 from above and form a coal cake 24. The front end of the coal extruder 21 is composed of a movable door 21a, and the rear end is composed of a rear wall 21b. The movable door 21a and the extrusion door 21b can be set in a predetermined position to form a stamping box. Therefore, by stamping the charged coal 23 with the stamper 22, the charged coal 23 can be molded into a predetermined block shape to obtain a coal cake 24. The molded coal cake 24 is set in the carbonization chamber 2 of the coke oven 1 by pushing it with the rear wall 21b at the rear end while the movable door 21a at the front end is open. The coal cake 24 set in the carbonization chamber 2 is then carbonized in the carbonization chamber 2. In FIG. 2, the portion of the coal cake 24 that contacts the movable door 21a at the front end is referred to as the inlet end 24a of the coal cake 24.

[0017] A feature of the method for producing a coal cake for coke production of the present invention is that, during molding of the coal cake 24 in the above-mentioned coal-loading extruder 21, the molding energy at the inlet end 24a of the coal cake 24 is equal to or greater than the energy Et (kJ / t) required to achieve the target density, regardless of the height of the coal cake.

[0018] Here, Et (kJ / t) is the target density (for example, 1100 kg / m 3) is the energy required to achieve the desired density. Even when the same stamping energy is applied to the coal, the density of the coal cake formed by the stamp charge method varies greatly depending on the brand, properties, particle size, etc. of the raw coal. Therefore, it is preferable to investigate in advance the correlation between the stamping energy E and the coal cake density ρ through offline testing and determine Et for each raw material. Suitable actual examples of Et will be explained in the following examples based on Table 1 and Figure 3.

[0019] In addition, in a preferred embodiment of the method for producing a coal cake for coke production of the present invention, Et may satisfy the following formula (1): Et≦ΣEi / (a×Li+b)···(1) where: Ei: Stamping energy transferred from the i-th stamper to the inlet end of the coal cake (kJ / t); Li: distance to the end of the i-th stamper in the direction of the furnace top (m), a, b: Coefficients determined for each coal.

[0020] When producing coal cakes using the stamp charge method, several dozen stampers are typically lined up toward the furnace top, and the molding energy of each stamper is transmitted to the surrounding area to compact the coal. Here, the stamping energy Ei (kJ / t) transmitted from the i-th stamper to the coal cake inlet end and the distance Li (m) toward the furnace top to the end of the i-th stamper are used to calculate the stamping energy Et at the coal cake inlet end.

[0021] The ΣEi / (a×Li+b) in equation (1) is calculated based on the following knowledge: The regression equation by Tsukasa and Midorikawa (Tsukasa Hirotoshi and Midorikawa Saburo: Distance attenuation equation for maximum acceleration and maximum velocity considering fault type and ground conditions, Journal of Structural Engineering, Architectural Institute of Japan, Vol. 523, 1999, pp. 63-70) shows that the maximum acceleration A at a distance X (km) from the epicenter tends to attenuate with distance. log(A)=b-log(Xz+c)-0.003X (b and c are coefficients related to the magnitude of the earthquake)

[0022] Here, when the distance is short, the second term, -0.003X, can be ignored, and the maximum acceleration is proportional to the inverse of the linear expression for X. Furthermore, if we consider that the maximum acceleration is proportional to the energy at that point, and expand this to the energy received by the coal from the weight, we can consider that the energy received by the coal at a position Li (m) away from the point where the weight falls is proportional to the inverse of the linear expression for Li: 1 / (a×Li+b).

[0023] ΣEi / (a×Li+b) can be made larger than Et by increasing the stamping speed of the stamper at the inlet end, increasing the stamper weight to increase the pressing energy, reducing the amount of coal charged, or a combination of these. In other words, any of the above methods can locally increase the stamping energy per weight of coal until the target density is reached, making it possible to make ΣEi / (a×Li+b) larger than Et, as shown in equation (1). [Example]

[0024] As an example, coal with a -3mm particle ratio of 90% and a moisture content of 10% was used to investigate the coal cake density ρ when the stamping energy E was changed in the range of 300 to 700 (kJ / t). The results are shown in Table 1 and Figure 3 below as the relationship between stamping energy and coal cake density in offline coal tests. From the graph in Figure 3, it can be seen that in the case of this coal, for example, 1100 (kg / cm 3 The target stamping energy Et to obtain the target density of 100 kJ / t is Et=547 (kJ / t).

[0025] As shown in Figure 3, for the above coal, when the coal cake density is y and the stamping energy is x, y = 585.5x 0.1 Here, the coefficient 585.5 and the exponent 0.1 take different values ​​for each type of coal. Therefore, if the coefficient is a and the exponent is b, the relationship between coal cake density and stamping energy can be expressed as y=ax, regardless of the type of coal. bIt can be shown that:

[0026] [Table 1]

[0027] In a preferred embodiment, the condition of the following formula (1) may be satisfied: Et≦ΣEi / (a×Li+b) (1), where Ei: stamping energy (kJ / t) transmitted from the i-th stamper to the inlet end of the coal cake, Li: distance (m) toward the furnace top to the end of the i-th stamper, and a, b: coefficients determined for each coal.

[0028] Here, if the damping coefficients calculated by placing markers at equal intervals on the coal to be stamped are a = 0.2 and b = 1.0, and if 30 hammers 1, 2, 3, 4, etc., each 40 cm long, are lined up at 10 cm intervals from a position 5 cm from the edge of the coal cake, the distribution of stamping energy will be as shown in Figure 4.

[0029] Using the above coal, Ei, Li, and Ei / (a×Li+b) were calculated according to the stamp charge method, with the stamping speed (times / sec), stamper pressure energy (kJ / time), and charging speed (t / sec) varied. ΣEi / (a×Li+b) was calculated for 30 stampers, and coal cakes were molded for Comparative Example 1 and Example 1. The collapse of the upper layer of the coal cake was then investigated when it was charged into the coke oven chamber. The coal cakes measured 0.43 m wide, 15.43 m long, and 6 m high, and the hopper into which the coal was charged was 7 m high. The molding conditions and results for Comparative Example 1 and Example 1 are shown in Tables 2 and 3.

[0030] [Table 2]

[0031] [Table 3]

[0032] From the graph in Figure 3, the energy required to achieve the target density at the inlet end of the coal cake is Et = 547 (kJ / t). In Comparative Example 1 shown in Table 2, Et by 30 stampers at the inlet end of the coal cake, i.e., ΣEi / (a × Li + b), was 434 kJ / t, which indicates that collapse of the coal cake occurred at the inlet end. On the other hand, in Example 1 shown in Table 3, Et by 30 stampers at the inlet end of the coal cake, i.e., ΣEi / (a × Li + b), was 547 kJ / t, which indicates that collapse of the coal cake did not occur at the inlet end.

[0033] In Example 1, it can be seen that the target density at the inlet end of the coal cake can be achieved by adjusting the stamping energy Et of hammer 1, which is closest to the inlet side of the coal cake, to 726 kJ / t or more, as shown in Table 3. As an example of how to achieve this, in this example, the weight of hammer 1 is increased by 45% compared to the other hammers, and adjustments are made to increase the energy applied in one drop.

[0034] From the above, it was found that a coal cake that does not collapse at the inlet end can be obtained by setting the molding energy at the inlet end of the coal cake to be equal to or greater than the energy Et (kJ / t) required to achieve the target density. [Industrial Applicability]

[0035] According to the coke manufacturing method of the present invention, the briquetting energy at the inlet end of the coal cake is set to be equal to or greater than the energy Et (kJ / t) required to achieve a target density, which can prevent the coal cake from collapsing from the inlet end of the coal cake and is therefore industrially useful. [Explanation of symbols]

[0036] 1. Coke oven 2. Carbonization chamber 21 Coal extrusion machine 21a Front movable door 21b Rear wall at rear end 22 Stamper 23 Coal 24 Coal Cake 24a Coal cake inlet end 25 Hopper

Claims

1. In a method for manufacturing a coal cake for coke production, the coal cake to be used for coke production is molded by a stamp charge method, At the inlet end of the coal cake, the shaping energy is equal to or greater than the energy Et (kJ / t) required to achieve a target density; The Et satisfies the following formula (1): Et≦ΣEi / (a×Li+b)...(1) where: Ei: stamping energy transferred from the i-th stamper to the inlet end of the coal cake (kJ / t); Li: distance to the end of the i-th stamper in the furnace top direction (m), a, b: Coefficients determined for each coal, A method for producing coal cake for coke production, comprising:

2. The Et is calculated for each coal based on the stamping energy E (kJ / t) and coal cake density ρ (kg / m ３ 2. The method for producing a coal cake for coke production according to claim 1, wherein the temperature is set based on a correlation between the temperature and the amount of the coal cake.

3. 3. The method for producing a coal cake for coke production according to claim 1, wherein the stamping energy E1 of the stamper closest to the inlet end is adjusted in the Ei.

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