JP7750252B2 - Method for producing coal cake for coke production - Google Patents

Description

The present invention relates to a method for manufacturing coal cake for coke production, in which coal cake for use in coke production is molded using the stamp charge method.

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

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.

JP 2018-44126 A

However, the strength of block-shaped coal cakes formed using the stamp charge method varies from place to place, and the upper part of the coal cake is not crushed from above by its own weight, so it has a low bulk density and is prone to low strength. As a result, when a coal cake is stamped a certain number of times to form it into a block shape, the upper part of the coal cake may collapse due to insufficient strength. In such cases, the coal cake with the collapsed upper part cannot be loaded into the carbonization chamber of the coke oven, and the coal cake cannot be carbonized to produce coke.

The object of the present invention is to solve the above problems and propose a method for manufacturing coal cake for coke production that can prevent the upper part of the coal cake from collapsing even when the coal cake is molded into a block shape using the stamp charge method.

In order to prevent the coal cake from collapsing, it is desirable that the density of the coal cake formed by the stamp charge method be 1100 kg/m ^{or more} . Therefore, in order to solve the above problem, in the present invention, the factors that cause the coal cake to collapse from the top were thoroughly investigated. As a result, the following findings were obtained.
1) When the height of the coal cake increases during stamping, the density of the lower part of the coal cake increases due to the weight of the coal above and the impact of stamping. On the other hand, the density of the upper part of the coal cake increases only due to the stamping directly above, so the density increase is small and the coal cake strength is insufficient.
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.

The present invention was made based on the above findings and is summarized as follows. Specifically, the method for producing a coal cake for coke production of the present invention is 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, characterized in that during molding of the coal cake, the molding energy is equal to or greater than the energy Et (kJ/t) required to achieve a target density at any height of the coal cake.

In the method for producing coal cake for coke production according to the present invention configured as described above,
(1) The Et is set for each coal based on the correlation between the stamping energy E (kJ/t) and the coal cake density ρ (kg/m ³ );
(2) The Et satisfies the following formula (1) at any height of the coal cake:
Et≦Eg+Es (1)
Where, Eg: Energy generated by the load when charging coal at height h (kJ/t)
Es: Stamping energy during charging at height h (kJ / t);
(3) The Es is kept constant at any height of the coal cake, and the coal charging speed is slowed as the height of the coal cake increases.
This is considered to be a more preferable solution.

According to the method for manufacturing coal cakes for coke production of the present invention, the molding energy is equal to or greater than the energy Et (kJ/t) required to achieve the target density at any height of the coal cake. This prevents the coal cake from collapsing from the top.

FIG. 1 is a diagram illustrating an embodiment of a conventionally known coke oven that uses the coal cake of the present invention. FIG. 1 is a diagram illustrating an embodiment of stamp charge equipment used in producing a coal cake according to the present invention. 1 is a graph showing an example of the relationship between stamping energy and coal cake density to explain Et in the present invention.

The following describes in detail the embodiments of the present invention. Note that the following embodiments are intended to exemplify devices and methods that embody the technical concepts of the present invention, and are not intended to limit the configuration to those described below. In other words, the technical concepts of the present invention can be modified in various ways within the technical scope set forth in the claims.

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

A heat regenerator 5 is integrally provided below the combustion chamber 3. The combustion chamber 3 and heat regenerator 5 combust fuel gas 6 with air 9 and discharge the resulting combustion exhaust gas 7 outside the coke oven 1, 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.

In the coke oven 1 configured as shown in Figure 1, the combustion chamber 3 and regenerator 5 are divided longitudinally into two sides, a combustion side and a withdrawal side, by a partition wall 8, as shown in Figure 1. Fuel gas 6 and burned combustion gas flow as shown by the arrows in Figure 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 chamber 2 to a temperature for carbonizing coal, for example, approximately 1100°C. After this state continues for approximately 20 to 30 minutes, the gas flow is reversed to switch between combustion and exhaust, and the combustion side and withdrawal side are alternately heated and repeatedly operated.

<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 rear wall 21b can be set in a predetermined position to form a stamping box. Therefore, by stamping the 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 while the front door 21a is open. The coal cake 24 set in the carbonization chamber 2 is then carbonized in the carbonization chamber 2.

A feature of the method for producing 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 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.

Here, Et (kJ/t) is the energy required to achieve a target density (e.g., 1100 kg/ ^m3 ). Even when the same stamping energy is applied to the coal, the density of the coal cake molded 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.

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) at any height of the coal cake:
Et≦Eg+Es (1)
Where, Eg: Energy generated by the load when charging coal at height h (kJ/t)
Es: Stamping energy during charging at height h (kJ / t);

Here, the energy Eg (kJ/t) generated by the load when charging coal at height h is defined as Eg = g x l (g: gravitational acceleration, l: distance the coal falls). For example, if coal is supplied from a hopper at a height of 7 m to create a coal cake 6 m high, Eg is calculated as Eg = g x l, assuming that the energy of the coal falling is converted into compression of the coal cake.

Furthermore, the stamping energy Es (kJ/t) during charging at a height h is defined as Es = (stamping speed (times/sec)) x (pressure energy per time by the stamper (J/time)) / (charging speed (t/sec)). In order to increase productivity while preventing the coal cake from collapsing, it is preferable to adjust the stamping energy Es during charging so that it increases as the height of the coal cake increases. Es can be increased by increasing the stamping speed, increasing the weight of the stamper to increase the pressurizing energy, reducing the amount of coal charged, or a combination of these methods.

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 below and Figure 3 as the relationship between stamping energy and coal cake density in offline coal testing. From the graph in Figure 3, for this coal, the target stamping energy Et to obtain a target density of, for example, 1100 (kg/cm ³ ) is Et = 547 (kJ/t).

As shown in Figure 3, for the above coal, when the coal cake density is y and the stamping energy is x, the equation y = 585.5 ^{x 0.1} can be obtained. 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 the coal cake density and the stamping energy can be expressed as y = a x ^b , regardless of the type of coal.

Using the above coal, coal cakes were molded in Comparative Example 1, Example 1, and Example 2 according to the stamp charge method, with the stamping speed (times/second), stamper pressure energy (kJ/time), and charging speed (t/second) varied. The presence or absence of collapse of the upper layer of the coal cake when charged into the carbonization chamber of the coke oven was then investigated. The shape of the coal cake was 0.43 m wide x 15.43 m long x 6 m high, and the height of the hopper into which the coal was charged was 7 m. The various molding conditions and results for Comparative Example 1, Example 1, and Example 2 are shown below in Tables 2, 3, and 4.

In Comparative Example 1, coal cake collapse occurred from the upper layer. This is thought to be because Es + Eg was less than the target Et = 547 (kJ/t) at heights of 3 m or more. On the other hand, in Examples 1 and 2, where Es + Eg was greater than the target Et = 547 (kJ/t) over the entire height of the coal cake, no coal cake collapse was observed from the upper layer.

From the above, it was found that during coal cake molding, at any height of the coal cake, if the molding energy is equal to or greater than the energy Et (kJ/t) required to achieve the target density, a coal cake can be obtained that does not collapse in the upper layer of the coal cake.

Furthermore, when comparing Example 1 and Example 2, the stamper pressure energy was 55.0 (kJ/cycle) in Example 1 and 50.0 (kJ/cycle) in Example 2. Furthermore, the time required for charging (integral value of charging speed) was shorter in Example 2 than in Example 1. Therefore, it was found that Example 2 is more productive and preferable than Example 1.

According to the coke manufacturing method of the present invention, during coal cake molding, the molding energy is equal to or greater than the energy Et (kJ/t) required to achieve the target density at any height of the coal cake. This prevents the coal cake from collapsing from the top, which is industrially useful.

REFERENCE SIGNS LIST 1 Coke oven 2 Carbonization chamber 21 Coal charging extruder 21a Movable door at front end 21b Rear wall at rear end 22 Stamper 23 Coal 24 Coal cake 25 Hopper

Claims (3)

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,
During molding of the coal cake, at any height of the coal cake, the molding energy is equal to or greater than the energy Et (kJ/t) required to achieve the target density;
The Et satisfies the following formula (1) at any height of the coal cake:
Et≦Eg+Es (1)
Where, Eg: Energy generated by the load when charging coal at height h (kJ/t)
Es: Stamping energy during charging at height h (kJ / t);
A method for producing coal cake for coke production, comprising: 2. The method for producing a coal cake for coke production according to claim 1, wherein the Et is set for each coal based on a correlation between stamping energy E (kJ/t) and coal cake density ρ (kg/m ³ ). 3. The method for producing a coal cake for coke production according to claim 1 or 2 , wherein Es is kept constant at any height of the coal cake, and the charging speed of the coal is slowed as the height of the coal cake increases.