JPH01252694A - Treating method of charging coal for coke oven - Google Patents

Abstract

PURPOSE:To attain heat saving in the drying of charging coal and enable miniaturization and simplification of drying facilities, by conducting preliminary drying of coal, classifying the coal into powder portion and coarse grain portion, conducting further drying and granulation of only the powder portion, joining the granulated coal with the coarse grain portion and feeding them into a coke oven. CONSTITUTION:A treating method of charging coal comprises conducting preliminary drying of coal so as to adjust the average water content of the coal to 2.0-5.0%, classifying the coal into powder portion and coarse grain portion by, e.g., blowing hot air thereinto, conducting further drying and granulation of only the powder portion so as to adjust the water content thereof to 2.0% or lower, joining the granulated coal with the coarse grain portion and feeding them into a coke oven.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for treating charged coal when drying and agglomerating coal and charging the same into a coke oven.

[Conventional technology]

When coal is dry distilled in a coke oven, in order to increase the strength of the product coke, for example, a fine powder portion of which about 80% has a particle size of 0.3 mm or less is separated from the raw coal with an average particle size of 1 mm or more, and this fine powder portion is compressed. A method is known in which, after being molded and agglomerated, it is merged with the coarse particles again and charged into a coke oven. At this time, the strength of the obtained lump coal is greatly influenced by the water content of the pulverized coal. FIG. 4 shows the relationship between the strength of this lump coal and the moisture content of the fine powder. As is clear from this figure, when the moisture content of pulverized coal exceeds 2.0%, the strength of agglomerated coal decreases significantly. Therefore, in order to obtain lump coal with excellent properties, the water content of pulverized coal was reduced to 2.
．． It can be said that it is necessary to dry the pulverized coal so that it becomes 0% or less.

In the conventional processing method, as shown in Fig. 5, raw coal a is dried in a dryer 1 until the moisture content is about 0.5%, and the coal sludge dried in the dryer 1 is classified. The powder is classified into a fine part C and a coarse part d by the machine 2. Here, the water content of the fine part C is about 1.5%, and the water content of the coarse part d is about 0.1%. The fine powder portion C is then agglomerated by the molding machine 3. The obtained agglomerated coal e rejoins the coarse grain portion d and then passes through the coke oven 4.
is charged into the In addition, in the dryer 1, the heat medium f heated by the heater 5 is circulating, and the raw coal a is heated by heat exchange with the heat medium f. (Unexamined Japanese Patent Publication No. 57-5358
(See Publication No. 7) [Problems to be Solved by the Invention] However, in this method, in order to reduce the moisture content of the fine powder part to the value required for agglomeration, for example, about 1.5%, the entire coking coal is It was necessary to reduce the moisture content to a very low value of around 0.5% as mentioned above. This is because the moisture content of the fine powder portion is higher than the moisture content of the entire coal.

FIG. 6 is a graph showing the relationship between the moisture content of the entire coal and the fine powder portion. In Figure 6, the proportion of the fine part accounts for about 1/3 of the total coal, and as is clear from this figure, in the range of low moisture content, the water content of the fine part is less than the total water content of the coal. It is about 1.0% higher than the content. Therefore, in order to reduce the moisture content of the fine powder to 2.0% or less, which is acceptable for agglomeration, it is necessary to dry the coal so that the moisture content of the entire coal is 1.0% or less. It becomes necessary. At this time, the moisture content of the coarse grain part is 0.5
% or less, resulting in more drying than necessary. Drying the entire coal to below the moisture content acceptable for agglomeration thus requires a very large dryer;
Also, the energy required for drying is large.

Therefore, the present invention firstly dries the coal to be charged into a coke oven, then classifies it into a fine part and a coarse part, and then dries only the fine part to the extent necessary for agglomeration. The purpose of the present invention is to agglomerate fine powder into coal for coke oven charging without using a large dryer and with reduced heat consumption.

[Means to solve the problem]

The present invention focuses on the fact that the moisture range for separating coal into coarse particles and fine powder is different from the moisture range for agglomerating fine powder, and separates the process to produce coking coal using small-scale equipment. By processing, the above objectives are achieved.

That is, the method for treating coal charged in a coke oven of the present invention involves initially drying the coal to an average moisture content in the range of 2.0 to 5.0%, and then classifying the coal into fine particles and coarse particles. The method is characterized in that only the fine powder portion is further dried to a water content of 2.0% or less and then agglomerated, and the resulting agglomerated coal is recombined with coarse coal and charged into a coke oven.

Alternatively, the coal subjected to the above-mentioned initial drying is classified into a fine part and a coarse part while blowing hot air, and the fine part that is accompanied by the hot air is selectively dried to a moisture content of 2.0% or less. It is also possible to agglomerate this dried fine powder portion, and to combine the obtained agglomerated coal with coarse coal again and charge it into a coke oven.

[Effect]

When separating raw coal into fine and coarse particles, it is important to collect the necessary amount of agglomeration substitute fine powder necessary to improve coke strength, and to ensure that the remaining coarse coal does not generate large amounts of dust. Therefore, it is necessary to ensure that almost no pulverized coal remains in the coarse coal. Therefore, to achieve these objectives, the classification performance for fine powder and coarse particles must be sufficient.

- In order to ensure the amount of fine powder for agglomeration and to perform classification that achieves dust generation prevention of coarse coal, the present invention makes it possible to reduce the moisture content of raw coal to 5.0% or less. I found that it was necessary. However, if the degree of dryness at this time is extremely increased, the amount of heat consumed for drying increases and the drying efficiency decreases. Furthermore, it is necessary to use a large dryer.

Therefore, these requirements were satisfied by setting the dryness of raw coal to 2.0% or more.

On the other hand, in order to agglomerate pulverized coal, the moisture content must be reduced to 2.
It is necessary to keep it below 0%. Therefore, raw coal with a moisture content I of 7 to 13%, in which coarse particles and fine particles are mixed, is used in an initial drying process to have an average moisture content of 2.0 to 13%.
After drying to 5.0%, the fine powder part is separated from the coarse part, and only this fine powder part is subjected to the second stage of drying. When this average moisture content is 2.0 to 5.0%, the moisture content of the fine powder portion is 3.0 to 6.0%. With such a moisture content, the fine powder portion cannot be agglomerated. Therefore, only the fine powder portion is further selectively dried to 2.0% or less.

This provides the dry conditions necessary for agglomeration.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 shows a processing device used in this example.

In addition, in the same figure, parts corresponding to those shown in FIG. 5 are indicated by the same reference numbers.

Raw coal a has a moisture content of approximately 3.0% by dryer 1.
Dry to a certain extent. As the dryer 1, a multi-tube rotary dryer similar to the conventional one was used. If dryer 1 has the capacity to set the maximum moisture content of raw coal to 11%, the amount of moisture reduction is 8.
．． The drying rate is reduced to 0%, and further drying is performed within a constant drying rate range. Therefore, it was possible to use a much smaller dryer 1 than in the conventional method.

The coal sludge dried in the dryer 1 is classified into a fine part C and a coarse part d by a classifier 2. As this classifier 2,
A centrifugal type or a mesh type was used. The moisture content of the fine powder portion C classified by the classifier 2 was approximately 4.0%. Therefore, in order to dry this fine powder part C to the extent necessary for agglomeration, a dryer 6 for fine powder was arranged on the downstream side. As the fine powder dryer 6, in order to increase the drying speed of the fine powder, a hot air drying type such as a flash dryer or a fluidized bed dryer, which has good ability to disintegrate pseudo particles, was used. As a result, the fine powder portion C was dried to a water content of 1.5%.

Here, the fine powder part C dried to 1.5% is separated from the hot air by a cyclone 7. Thereafter, the fine powder portion C was applied to a molding machine 3 such as a roll compactor as in the conventional example, and molded into a gutter shape. Then, the obtained agglomerated coal e was merged into the coarse grain portion d in the same manner as in the conventional method, and charged into the coke oven 4.

When raw coal a is dried in this way, the capacity and load of the dryer 1, which accounts for the main part of the equipment cost of this process, can be significantly reduced. Table 1 shows a comparison between the conventional method and the present invention method when a multi-tube rotary dryer is used as the dryer 1.

As described above, according to this embodiment, the heat transfer area of the dryer 1 was reduced by 43%, and the dryer 1 was made more compact.

FIG. 2 shows a processing device used in a second embodiment of the invention. In this embodiment, the steps up to the dryer 1 are the same as those in the first embodiment, so the explanation will be omitted.

The dried coal sludge is classified into a fine part C and a coarse part d by a classifier 2. A centrifugal classifier was used as the classifier 2, and hot air g from the hot air generator 8 was blown into the classifier 2.

FIG. 3 shows a conceptual diagram of the structure of the classifier used in this example. This classifier has a double structure of an inner chamber 10 and an outer chamber 11 separated by an inner wall 9. A hole 12 is formed in the lower part of the inner wall 9 to communicate between the inner chamber 10 and the outer chamber 11. In addition, the inner chamber 10 includes a hot air generating furnace 8 (
A hot air introduction pipe 13 for introducing hot air g from a source (see FIG. 2) is connected thereto.

Since the moisture content of the dried coal sludge is lowered to 5.0% or less, the bonding force between the coal particles is weakened. Therefore, the blown hot air g becomes an internally circulating gas h, and when it circulates between the inner chamber 10 and the outer chamber 11 partitioned by the inner wall 9, it accompanies the coal sludge. During this circulation process, the coal sludge is easily classified into a fine part C and a coarse part ld. That is, the fine powder portion C is discharged into the outer chamber 11 along with the internal circulating gas h, and then separated from the internal circulating gas h and taken out from the fine powder discharge pipe 14 provided at the bottom of the outer chamber 11. On the other hand, the coarse particles d that are difficult to float in the internally circulating gas h are
The coarse particles accumulate in the inner chamber 10 and are taken out through a coarse particle discharge pipe 15 provided at the bottom thereof.

As the hot air g mixed into the internally circulating gas h, exhaust gas produced in the hot air generating furnace 8 or generated by combustion in another device is used. When the internally circulating gas h whose temperature has been raised by blowing in the hot air g comes into contact with the coal, the fine part C is rapidly dried due to its good thermal conductivity with the gas. On the other hand, the coarse grain portion d has poor thermal conductivity with the gas, and also has a short contact time with the internally circulating gas h. Therefore,
The coarse particle portion d is discharged outside the system without being dried at all.

In this way, selective drying of the fine powder portion C is performed in the classifier 2. For example, the moisture content of pulverized coal in a coal sludge with a moisture content of 3.0% was 4.0%. Third
By treating the coal using the classifier 2 with the structure shown in the figure, the fine powder portion C contains the moisture necessary for agglomeration! (2,
We were able to reduce the moisture content to 1.5% (0%) or less. At this time, the moisture content of the coarse grain part d ranges from 2.6% to 2.
．． It only decreased to 5%. That is, hot air generating furnace 8
The amount of heat of the hot air g blown from is efficiently consumed for drying the fine powder part C. Therefore, the required amount of hot air could be reduced.

A part of the fine powder part is discharged from the classifier 2 through the exhaust pipe 16 together with the exhaust gas l. The fine powder part floating in the exhaust gas l is separated from the exhaust gas l by a cyclone 7 (see FIG. 2) and sent to the molding machine 3 as a second fine powder part J. On the other hand, the exhaust gas l from which the second wl powder part J was separated by the cyclone 7
After being collected in the polishing machine 17, it is discharged outside the system. Further, the fine powder portion C separated by the classifier 2 is also fed into the molding machine 3.

In this embodiment, the classifier 2 is
Due to the internal circulating gas h formed within, the classification effect is slightly reduced. However, since the fine powder portion C is selectively dried in this classification stage, there is no need to provide the fine powder dryer 6 shown in FIG. 1 on the downstream side of the classifier 2. Therefore, the load on equipment is reduced accordingly.

〔Effect of the invention〕

As explained above, in the present invention, coal after initial drying is classified into a fine part and a coarse part, and the fine part is further dried to the extent necessary for agglomeration. Alternatively, during the classification process, hot air is blown into a classifier to selectively dry the fine powder portion. This makes it possible to avoid excessive drying of the coarse grains,
With the reduced heat consumption, it is possible to adjust the moisture content of the fine powder portion to the level required for agglomeration. Furthermore, since the drying efficiency is good, the equipment can be made small and simple in structure.

[Brief explanation of the drawing]

Fig. 1 shows an outline of the processing equipment used in the first embodiment of the present invention, Fig. 2 shows an outline of the processing equipment used in the second embodiment, and Fig. 3 shows the classification of the second embodiment. Shows the structure of the machine. On the other hand, Fig. 4 is a graph showing the relationship between the moisture content of pulverized coal and the strength index ratio of agglomerated coal, Fig. 5 shows a conventional treatment equipment, and Fig. 6 shows the relationship between the moisture content of pulverized coal and the strength index ratio of agglomerated coal. It is a graph showing the relationship between the content and the water content of the fine powder part. Patent applicant: Shin Nippon IM Steel Co., Ltd. Agent: Masu Kobori (and 2 others) No. 1 Figure 7: Cyclono Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 6 Returned total moisture (%)

Claims (1)

[Claims] 1. After initially drying the coal to an average moisture content in the range of 2.0 to 5.0%, it is classified into a fine part and a coarse part, and only the fine part contains further water. A method for treating coal charged in a coke oven, characterized in that the coal is dried to a content of 2.0% or less and then agglomerated, and the obtained agglomerated coal is recombined with coarse granulated coal and charged into a coke oven. 2. Classifying the initially dried coal as described in claim 1 into a fine part and a coarse part while blowing hot air,
selectively drying the fine powder part accompanied by the hot air to a moisture content of 2.0% or less, agglomerating the dried fine powder part,
A method for treating coal charged in a coke oven, characterized in that the obtained agglomerated coal is recombined with coarse granulated coal and charged into a coke oven.