JP6863001B2 - How to make coke - Google Patents

Description

The present invention relates to a method for producing coke, and more particularly to a method for producing briquette to be charged into a coke oven carbonization chamber.

In order to improve productivity (production amount) when coal is carbonized to produce coke, a method is known in which briquette formed by molding coal is charged into a coke oven carbonization chamber together with pulverized coal. When briquette made by molding coal is charged into the coke oven carbonization chamber together with pulverized coal, the bulk density of the charged coal can be improved and the coke strength can be increased, and more non-slightly caking coal can be used. It becomes.

The use of briquette in producing coke is described in, for example, Patent Document 1. In Patent Document 1, a briquette having a shape called a massec type (44 mm × 44 mm × 26 mm) is molded with an apparent density of 1.14 (g / cm ³ ), and the blending ratio of the briquette is 30 of the charged charcoal. A technology of ~ 50% by mass has been disclosed, and it is stated that this technology can improve the bulk density of briquette.

JP-A-59-58083 Japanese Unexamined Patent Publication No. 2016-69463

In the production of coke, in addition to the fact that there is no variation in coke quality such as coke strength, it is also necessary to prevent damage to the coke oven body due to coal expansion during carbonization.
According to the method described in Patent Document 1, the bulk density can be improved to a certain extent, but when coal is charged into the coke oven carbonization chamber, the briquette may be locally accumulated, that is, the briquette may be segregated. The present inventors have discovered that segregation of briquette causes a local increase in the amount of expansion of briquette (including briquette), and damage to the refractory constituting the carbonization chamber may become significant. .. In addition, the present inventors have found that segregation of briquette also causes variations in coke quality.

On the other hand, Patent Document 2 describes a method of suppressing the local accumulation of briquette. Patent Document 2 has an object that segregation of briquette occurs when briquette is charged on pulverized coal inside a coal tower in which briquette and pulverized coal are charged into a charging vehicle. Then, by using the briquette having a shape in which the rotation coefficient considering the moment of inertia of the briquette becomes a predetermined value, there is a technique of suppressing the rolling of the briquette and suppressing the segregation of the briquette inside the coal tower. It is disclosed.

However, it has been found that the segregation of briquette in the carbonization chamber of the coke oven cannot be eliminated by the method described in Patent Document 2, the coke quality varies, and the refractory material in the carbonization chamber is damaged by the local increase in the expansion amount of charged coal. The present inventors obtained.

The present invention has been made in view of such circumstances. By eliminating the segregation of briquette in the coke oven carbonization chamber, the variation in coke quality is suppressed, and the carbonization chamber due to the local increase in the expansion amount of charged coal. It is an object of the present invention to provide a method for producing coke capable of preventing damage to refractories.

In order to achieve the above object, the present invention is a method for producing coke by charging briquette formed by molding coal together with pulverized coal into a carbonization chamber from a charging inlet at the top of a coke oven.
The briquette has a bulk specific gravity of 0.9 to 1.2 (ton / m ³ ).
Looking at the briquette from the direction in which the projected area is maximum, the ratio a of the minimum width b (mm) of the briquette to the maximum width a (mm) of the briquette in the direction orthogonal to the minimum width direction. The size of the briquette is such that / b is 1.0 to 1.2, the maximum width a is 30 mm to 70 mm, and the distance between the briquettes is minimized when the briquette is sandwiched between a pair of parallel planes. Assuming that the thickness is t (mm), a / t is 4.4 to 6.7.
The coal blended in the briquette is characterized by containing 1% by mass or more of coal that has passed through a sieve of 90 μm described in JIS Z8801-1.

In the conventional operation, the shape of the briquette is such that the briquette does not slide down on the pulverized coal. On the other hand, in the present invention, the shape of the briquette is such that the briquette easily slides down on the pulverized coal. As the briquette slides down on the pulverized coal, it becomes difficult for the briquette to stay below the charging inlet. As a result, the briquette can be distributed over the entire carbonization chamber, and segregation of the briquette can be prevented.

Further, in the method for producing coke according to the present invention, a part or all of the coal blended in the briquette may be coal that has fallen from the coal transport means.

The brand of coal that has fallen from the coal transport means (hereinafter referred to as "falling coal") may be unknown, and the amount of thermal expansion during carbonization is unknown, so the amount to be added to the coal charged into the carbonization chamber is limited. Will be done. On the other hand, it is desired to use falling coal as a substitute for expensive coke coal.
According to the present invention, since the effect of preventing segregation of briquette can be obtained, it is possible to suppress fluctuations in the amount of thermal expansion for each carbonization chamber portion due to charged coal in which pulverized coal and briquette are mixed. Therefore, a large amount of falling coal whose thermal expansion amount is unknown can be added to the charged coal.

When the briquette in the present invention is charged into the carbonization chamber from the charging inlet at the top of the coke oven, it tends to slide down from the position where it was dropped and distributed throughout the carbonization chamber. Segregation of briquette can be prevented. As a result, variation in coke quality can be suppressed, and damage to the refractory at the coke discharge port (coke side of the carbonization chamber) and the like can be prevented.
In addition, falling coal, which has been disposed of as miscellaneous coal (coal of unknown brand) as cheap coal, can be used as a raw material for coke, and the amount of expensive coke coal used can be reduced.

It is a flow chart which shows the manufacturing process of the briquette in the method of manufacturing coke which concerns on one Embodiment of this invention. It is a schematic diagram of a molding machine. It is a perspective view of the briquette produced by the method of producing coke according to this embodiment. (A) is a plan view of the briquette, and (B) is a cross-sectional view of the briquette.

Subsequently, an embodiment embodying the present invention will be described with reference to the attached drawings, and the present invention will be understood.

In the method for producing coke according to an embodiment of the present invention, briquette formed by molding coal is charged into a carbonization chamber together with pulverized coal from a charging inlet at the top of a coke oven, and carbonized at a high temperature to produce coke.

FIG. 1 shows the process of producing briquette.
Coking coal containing a plurality of types of coal is crushed by a crusher, a binder is added to the crushed coking coal, and the coking coal is kneaded by a kneader. As the binder, a conventionally known binder can be used.

The kneaded coking coal is put into a molding machine and becomes briquette.
FIG. 2 shows an example of a molding machine. The molding machine 10 in the present embodiment is a double roll type molding machine, and is a hopper 13 into which the coking coal is charged, a pair of rolls 11 for compression molding the coking coal, and a pair of rolls 11 installed in the hopper 13. It is roughly composed of a screw feeder 14 that supplies coking coal between them. A plurality of recesses 12 (pockets) are formed on the roll surface of each roll 11, and the recess 12 formed in one roll 11 and the recess 12 formed in the other roll 11 are aligned in the circumferential direction. There is.

When the coking coal is put into the hopper 13 from the charging port 15, the coking coal in the hopper 13 is sent between the pair of rolls 11 by the screw feeder 14. The pair of rolls 11 arranged side by side rotate in opposite directions to each other, and the briquette inserted between the pair of rolls 11 passes through the pair of rolls 11 and has a recess 12 formed in the one roll 11. It is compression-molded by the recess 12 formed in the other roll 11 to form briquette.
Since the shape of the recess 12 defines the shape of the briquette, the briquette having a desired shape can be produced by changing the shape of the recess 12.

Hereinafter, the briquette produced by the method for producing coke according to the present embodiment will be described.
The bulk specific gravity of the briquette is 0.9 to 1.2 (ton / m ³ ).
By setting the bulk specific gravity of the briquette to 0.9 (ton / m ³ ) or more, it is possible to prevent a decrease in productivity due to a decrease in the bulk specific gravity of the charged coal. On the other hand, if the bulk specific gravity of the briquette exceeds 1.2 (ton / m ³ ), the expansion allowance of the briquette becomes too large, and the carbonization chamber furnace wall may be significantly damaged.

The bulk specific gravity of the molded charcoal is measured according to the "method for measuring the density and specific gravity by the in-liquid weighing method" described in JIS Z8807 "Measuring direction of individual density and specific gravity".

An example of the produced briquette (Masek type) is shown in FIG.
Looking at the briquette from the direction in which the projected area is maximum, if the minimum width of the briquette is b (mm) and the maximum width of the briquette in the direction orthogonal to the minimum width direction is a (mm), a / b is It becomes 1.0 to 1.2 (see FIG. 4 (A)).

When a / b exceeds 1.2, the briquette tends to be elongated, and the briquette sticks into the charged coal in the carbonization chamber, so that segregation of the briquette cannot be prevented. On the other hand, from the definition of the minimum width b and the maximum width a of the briquette, a / b cannot be less than 1.0.
In this embodiment, it is assumed that the briquette has a maximum width a of about 30 mm to 70 mm.

Further, assuming that the thickness t (mm) of the briquette is the dimension that minimizes the distance between the planes 16 when the briquette is sandwiched between a pair of parallel planes 16, a / t is 4.4 to 6.7. (See FIG. 4 (B)).

When a / t exceeds 6.7, segregation of briquette tends to be remarkable, which is not preferable. When an external force is applied to move (slide down) the briquette on or in the pulverized coal, the briquette does not move and tends to rotate on the spot.

If a / b and a / t are specified to form a briquette having a shape that allows it to slip easily, the briquette may crack or chip during transportation or drop loading, and the slip-promoting effect may be lost. When is less than 4.4, the phenomenon becomes remarkable. Therefore, by setting a / t to 4.4 or more, cracking or chipping of the briquette is prevented, and the effect of promoting the sliding of the briquette is maintained.

However, the briquette may be cracked or chipped due to the above requirements. Therefore, in the present embodiment, the amount of coal passing through the sieve 90 μm described in JIS Z8801-1 “Test Sieve-Part 1: Metal Net Sieve” is 1% by mass or more (preferably 6% by mass or more). Coal is mixed (securing a certain amount of fine powder) to make briquette. As a result, the strength of the briquette is improved, and it is possible to prevent the shape change of the briquette due to cracking or chipping during transportation of the briquette.

In Patent Document 2, the value corresponding to a / b of the present invention is set to 1 / 0.8 = 1.25 to 1 / 0.5 = 2 (paragraphs [0058] and [0060] of Patent Document 2]. ]reference). Further, the numerical value corresponding to a / t is referred to as an aspect ratio and is set to 1.1 to 3.5 (see paragraph [0033] of Patent Document 2).

In the method for producing coke according to the present embodiment, even if part or all of the coal to be mixed in the briquette is used as falling coal dropped from a coal transport means (conveyor) for transporting coal from the yard to the coke oven. Good.
According to this embodiment, since the effect of preventing segregation of the briquette can be obtained, a large amount of falling coal whose thermal expansion amount is unknown can be blended into the charged coal.

Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, but is within the scope of the claims. It also includes other possible embodiments and variations. For example, in the above embodiment, the double roll type is used as the molding machine, but the present invention is not limited to this, and other types of molding machines may be used. Further, in the present embodiment, the Masec type is shown as an example of the produced briquette, but the present invention is not limited to this, and other shapes such as a pillow type may be used.

In order to verify the effect of the present invention, briquette was produced by changing the molding conditions in various ways, and the variation in coke strength (σDI) and the extrusion load were evaluated.

After being discharged from the coke oven, 100 (kg) samples were sampled at 10 points from the wet-extinguished coke. At that time, as the coke to be sampled, the coke around the pot mouth and the top of the furnace are excluded because they are greatly affected by the variation caused by the furnace body. , The coke existing from the middle to the bottom in the furnace height direction except near the top of the furnace was sampled with a sampler.
As for the extrusion load, the load during coke extrusion was measured.

Table 1 shows a list of molding conditions and evaluation results. In this verification, briquette having a maximum width a of 40 mm was used.

σDI is evaluated by the variation (standard deviation) with respect to the target value of DI (85% in this test), which is commonly used as an index of coke strength, and σ ≧ 1.0 is × (impossible), 1.0. > Σ ≧ 0.5 was defined as ◯ (good), and 0.5> σ was defined as ⊚ (excellent).
Regarding the extrusion load, based on Comparative Example 2 in which the value of the extrusion load was the smallest in Comparative Example, the case where the extrusion load was greater than or equal to the value of Comparative Example 2 was rejected, and the extrusion load was the value of Comparative Example 2. Cases that were less than were accepted.

The following can be seen from the table.
-In Examples 1 to 5, both σDI and extrusion load were good, but in Comparative Examples 1 to 4, both σDI and extrusion load did not reach the target levels.
-In Comparative Example 1, a / b is larger than 1.2. It is presumed that the briquette was segregated due to the briquette sticking into the pulverized coal at the drop loading position, and the σDI and the extrusion load increased.
-In Comparative Example 2, a / t is less than 4.4. It is said that the briquette cracked due to the impact at the time of dropping, and the briquette pieces (a / b exceeded 1.2) after the cracking pierced into the pulverized coal, causing segregation of the briquette and increasing σDI and extrusion load. Inferred.
-In Comparative Example 3, a / t is larger than 6.7. Since the shape is close to a round shape, it is presumed that segregation of the briquette occurred by staying at the drop loading position without moving (sliding), and the σDI and extrusion load increased.
-In Comparative Example 4, the amount of coal (-90 μm coal) passing through the sieve 90 μm described in JIS Z8801-1 is less than 1% by mass. Since there was briquette with low strength, the briquette cracked due to the impact of dropping, and the briquette pieces (a / b are over 1.2) after the cracking pierced into the pulverized coal, causing segregation of the briquette. , ΣDI and extrusion load are presumed to have increased.

10: Molding machine, 11: Roll, 12: Recess, 13: Hopper, 14: Screw feeder, 15: Inlet, 16: Flat surface

Claims (2)

In the method of producing coke by charging briquette, which is made by molding coal, together with pulverized coal into the carbonization chamber from the inlet at the top of the coke oven.
The briquette has a bulk specific gravity of 0.9 to 1.2 (ton / m ³ ).
Looking at the briquette from the direction in which the projected area is maximum, the ratio a of the minimum width b (mm) of the briquette to the maximum width a (mm) of the briquette in the direction orthogonal to the minimum width direction. The size of the briquette is such that / b is 1.0 to 1.2, the maximum width a is 30 mm to 70 mm, and the distance between the briquettes is minimized when the briquette is sandwiched between a pair of parallel planes. Assuming that the thickness is t (mm), a / t is 4.4 to 6.7.
A method for producing coke, which comprises 1% by mass or more of coal passing through a sieve of 90 μm according to JIS Z8801-1. The method for producing coke according to claim 1, wherein part or all of the coal blended in the briquette is coal that has fallen from the coal transport means.

Images