JPH0637625B2 - Method for producing coal / water slurry - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing coal / water slurry, and more particularly to a method for adjusting a water content ratio for adding water to coal to process it into a pulverized coal slurry. is there.

BACKGROUND OF THE INVENTION In recent years, coal can be easily handled for transportation and storage, and can be used in the same way as heavy oil when it is burned. Therefore, a small amount of water and a small amount of additives (dispersing agent, stabilizing agent, consuming agent) are added to pulverized coal. Attempts have been made to use coal-water mixed fuel (coal-water slurry) in the form of slurry by mixing foaming agents, etc.).

In the above coal / water mixed fuel, pulverized coal is required to have a high concentration of about 65 to 80% by weight on a wet basis, and further, it has a good slurry property in terms of fluidity and stability over a long period of time. A certain pulverized coal particle size composition is required to maintain the properties.

That is, pulverized coal is required to be distributed in a wide range in terms of particle size, and not only those having a large particle size to a minute particle size but also the type of coal to be used in order to increase the packing density. Although depending on this, an extremely large amount of ultrafine coal of less than 3 μm, such as 3 to 15%, is required.

The method for producing coal / water slurry that meets these conditions includes:
Conventionally, a high-concentration wet grinding method and a low-concentration wet grinding method are roughly classified.

The high-concentration wet pulverization method is one in which the pulverizer is supplied with coal, additives, and the required amount of water in advance to pulverize and pulverizes, and the product slurry is discharged directly from this pulverizer. In addition, it has the advantage of not requiring dehydration and mixing steps unlike the low-concentration wet pulverization method described below, but it requires a large amount of power for pulverization per unit weight of coal, and it also provides high-concentration products directly from the pulverizer. Since a slurry is obtained, it is impossible to classify this product slurry, and therefore
There is a drawback that it is difficult to adjust the particle size distribution structure of the pulverized coal in the product slurry.

On the other hand, in the low-concentration wet pulverization method, as shown in FIG. 4, the amount of coal 2 supplied to the pulverizer 1 is larger than that required for the product slurry separately supplied to the pulverizer 1. It is ground using water 4 to give a low-concentration slurry 3. still,
The coal concentration in this case is about 30%.

The low-concentration slurry 3 discharged from the crusher 1 is usually
After further adding water 5 for classification, it is supplied to a wet classifier 6 such as a hydrocyclone and classified into a low-concentration slurry 7 containing coarse coal and a low-concentration slurry 8 containing fine coal.

The low-concentration slurry 7 containing the pulverized coal is returned to the crusher 1 and re-pulverized, while the low-concentration slurry 8 containing the pulverized coal is dehydrated by the dehydrator 9 to form a cake, which is then used for water content adjustment. The water 11 and the additive 12 are kneaded in the kneader 10 to form a high-concentration slurry 13 having a predetermined water content.

Further, the high-concentration slurry 13 is supplied to the stirrer 14 and, after stirring, the coal / water slurry 1 having a predetermined fluidity and concentration.
5 is transferred to a storage process or the like (not shown).

The wastewater 16 separated from the low-concentration slurry 8 by the dehydrator 9 is circulated to the crusher 1 for reuse.

According to the low-concentration wet pulverization method described above, the power required for the pulverizer 1 is relatively small, and the low-concentration slurry 3 discharged from the pulverizer 1 is classified after hydration, if necessary.
Since the coarse coal contained in the low-concentration slurry 3 can be re-ground, it becomes easy to adjust the particle size distribution configuration of the fine coal in the product slurry 15, and a deashing step can be set up if necessary. And so on.

However, since a vacuum type filter or a press type filter is generally used as the dehydrator 9, the water content of the cake of the dehydrator cannot be adjusted to a constant value. Therefore,
In the dehydrator 9, the water content is lowered to a level lower than the water content contained in the product slurry 15, and the kneader 1 in the subsequent step is used.
At 0, it is necessary to supply a small amount of water 11 again to adjust the water content to a predetermined level.

In particular, as described above, the product slurry 15 needs to have a high concentration of about 65 to 80%, that is, a low water content of about 20 to 35%. In order to reduce the water content to a lower level in the dehydrator 9, , A lot of power is needed.

Then, since the power is further consumed in the stage of adding the adjusted water 11 again and then kneading and stirring, the power required in the pulverizer itself is far less than that in the high-concentration pulverization method, but the coal / water slurry production system The overall required power is almost the same as the high-concentration pulverization method.

Further, in terms of equipment cost, a large amount of cost is required for the dehydration, kneading and stirring steps.

Therefore, as shown in FIG. 5, it has been proposed to mix the dry pulverized coal 17 into the low-concentration slurry 3 discharged from the crusher 1 and to omit the dehydration and kneading steps.

That is, the crusher 1 supplied with the coal 2 and the water 4 produced the low-concentration slurry 3 as in the case of the low-concentration wet pulverization method shown in FIG. 4, while only the coal 2 was supplied. Another pulverizer 18 produces a pulverized coal 17 in a dry state by a so-called dry pulverization method.

After that, the low-concentration slurry 3 and the pulverized coal 17 are added to the additive 1
2 is mixed and stirred by a stirrer 14 to produce a coal / water product slurry 15 having a predetermined fluidity and concentration.

However, a large amount of dried pulverized coal 17 is required for the low-concentration slurry 3, and for example, the low-concentration slurry 3 with a coal concentration of 30% is used to produce a high-concentration product slurry 15 with a coal concentration of 70%. In that case, about 4.5 times the amount of pulverized coal 17 in the low-concentration slurry 3 is required, and as a result, 80% or more of the total amount of coal needs to be supplied in a dry state.

However, the dry pulverization method for pulverizing coal into pulverized coal in a dry state requires a large amount of power for pulverization per unit weight of coal as compared with the wet pulverization method. It will be almost the same.

OBJECT OF THE INVENTION The present invention has been devised in view of the above circumstances, and provides a method for producing a coal / water slurry capable of reducing the overall power consumption required for producing a coal / water slurry. It is intended.

Configuration of the invention, in order to achieve the above object, the main means adopted by the present invention, the gist thereof, is to add water to the coal, a coal-water slurry for processing into a slurry-like pulverized coal of a predetermined water content ratio In the manufacturing method of 1, the pulverized coal that was pulverized with water and became a slurry with a low concentration was partially dehydrated so that it had a higher water content than the product slurry, and this was mixed with pulverized coal that had a lower water content than the product slurry. Is a method for producing a coal / water slurry having a predetermined concentration by producing a coal / water slurry.

Object of the invention By pulverizing coal with water, a low concentration slurry-like pulverized coal is produced while suppressing the required power for pulverization per unit weight of coal, and further, this low-concentration slurry-like pulverized coal is produced. Is partially dehydrated to obtain pulverized coal having a higher water content than the product slurry.

Then, this pulverized coal is mixed with a small amount of pulverized coal having a water content smaller than that of a product slurry obtained by separately pulverizing coal to produce a coal / water slurry having a predetermined concentration.

Embodiments Embodiments embodying the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.

The following examples are examples of embodying the present invention and are not of the nature to limit the technical scope of the present invention.

FIG. 1 is a system diagram of a manufacturing apparatus capable of carrying out the method for manufacturing coal / water slurry according to an embodiment of the present invention.
2 and 3 are system diagrams of a manufacturing apparatus capable of carrying out a method for manufacturing a coal / water slurry according to another embodiment of the present invention.

Further, elements common to those of the conventional method for producing coal / water slurry described based on the production apparatus shown in FIGS. 4 and 5 will be described using the same reference numerals.

In the method for producing coal / water slurry according to this embodiment,
As shown in the figure, most of the coal 2 is required for the product slurry separately supplied to the crusher 1 in the crusher 1 as in the case of the conventional low-concentration wet crushing method (see FIG. 4). Is pulverized using a larger amount of water 4 to obtain a low-concentration slurry 3. By adjusting the coal concentration in this case to about 30%, the required power for crushing per unit weight of coal in the crusher 1 is minimized.

The low-concentration slurry 3 discharged from the crusher 1 is usually
After further adding water 5 to carry out classification, it is supplied to a wet classifier 6 and a low-concentration slurry 7 containing coarse coal and a low-concentration slurry containing fine coal (a low-concentration slurry of fine coal) Be classified into.

The low-concentration slurry 7 containing the pulverized coal is returned to the crusher 1 and re-pulverized, while the low-concentration slurry 8 containing the pulverized coal is partially dehydrated by the dehydrator 9 to form a cake-like product having a higher water content than the product slurry. Alternatively, it becomes slurry-like pulverized coal 20. In this case, the water content in the pulverized coal 20 is kept at a level slightly higher than the water content in the product slurry 15 described later, and is set to, for example, about 35%. The dehydration work in the dehydrator 9 with the water content after dehydration of 30 to 40% is relatively easy depending on the particle size distribution of the pulverized coal and the water absorption, so that the dehydrator can be downsized. In addition, it requires less power for dehydration.

On the other hand, a part of the coal 2 is crushed by a crusher 18 by a dry crushing method with a closed circuit and supplied to an air classifier 21.

The pulverized coal 23 classified by the air classifier 21 is returned to the pulverizer 18 and re-pulverized, while the pulverized coal is stored in the storage bottle 24 as the pulverized coal 22 having less water content than the product slurry 15.
Stored in.

The pulverized coal 20 from the dehydrator 9 and the pulverized coal 22 quantitatively cut out from the storage bottle 24 are blended at a predetermined ratio, and an additive 12 is further added to the pulverized coal 20 and / or the agitator 14 for sufficient mixing. The coal / water slurry 15 having a predetermined concentration is manufactured by mixing and stirring with.

At this time, since the pulverized coal 20 from the dehydrator 9 has been dehydrated to a water content of a level slightly higher than the water content in the product slurry 15 as described above, it is substantially necessary to adjust to a predetermined concentration. The amount of the pulverized coal 22 in the dry state is smaller than that of the pulverized coal 20.

For example, when the product slurry 15 having a concentration of 70% is produced by using the cake-like pulverized coal 20 having a water content of 35%, a dry state of about 1/4 of the amount of the pulverized coal in the cake-like pulverized coal 20 is produced. The pulverized coal 22 is sufficient, and about 1/5 of the total amount of coal in the product slurry 15 may be mixed in a substantially dry state.

Therefore, the amount of coal 2 that needs to be pulverized by the dry pulverization method, which requires a large amount of pulverization power, is small, the increase in the required pulverization power can be suppressed to a minimum, and the fine powder in such a dry state can be suppressed. A small handling amount of the charcoal 22 is also preferable in terms of safety.

However, the water content of the pulverized coal 20 after the partial dehydration is 40%.
If it exceeds, the required amount of the pulverized coal 22 in a dry state rapidly increases, so that the water content of the pulverized coal 20 should be kept below this.

In addition, the particle size of the pulverized coal 22 in the dry state is set to the pulverized coal 2
By making the ultrafine powder finer than the particle size of 0, it becomes possible to easily adjust the particle size composition of the pulverized coal in the product slurry 15.

As described above, in the method for producing a coal / water slurry according to the embodiment of the present invention, most of the coal is pulverized by the low-concentration wet pulverization method, and the amount of coal required to be pulverized by the dry pulverization method is minimized. In addition, since the work in the dehydrator is limited to a range where dehydration is relatively easy, the power consumption required for producing the product slurry can be minimized.

Further, the amount of coal that needs to be pulverized by the dry pulverization method is an amount suitable for producing the ultrafine coal that constitutes the product slurry, and as shown in the first diagram, the classifier 21 is incorporated,
It can be said that the closed circuit system is an apparatus suitable for producing ultrafine coal on an industrial scale.

FIG. 2 shows a second embodiment according to the present invention, and only the differences from the above-mentioned first embodiment will be described below.

In this case, since the ultra-fine coal that constitutes the product slurry 15 is produced by the low-concentration wet-pulverization method, two wet-pulverizers 1 and 25 and wet classifiers 6 and 27 are arranged, and the ultra-fine coal containing the ultra-fine coal has a low concentration. A part of the low-concentration slurry 7 containing the coarse coal classified by the wet classifier 6 attached to the crusher 1 is supplied to the crusher 25 that manufactures the slurry 26. Then, the low-concentration slurry 8 containing the pulverized coal and the low-concentration slurry 26 containing the ultra-fine coal are supplied to the common dehydrator 9 and partially dehydrated in the premixed state to form the cake-like pulverized coal 20. .

On the other hand, a part of the coal 2 is crushed by the crusher 18 by the dry crushing method.
Is pulverized to form pulverized coal 22 having a normal particle size. For this reason,
This dry crushing can also be performed by an open circuit crushing method as shown in the figure.

The pulverized coals 20 and 22 together with the additive 12 are kneaders 10.
After being kneaded in, the finishing crusher 28 is made into a slurry with a predetermined concentration.
The product slurry 15 is supplied to the finishing crusher 28, and the final particle size adjustment and sufficient agitation are performed by the finishing crusher 28.
Becomes

Furthermore, FIG. 3 shows a third embodiment according to the present invention, and only the differences from the above-described first and second embodiments will be described below.

At the outlet of the wet crusher 1 for crushing most of the coal 2, a mechanical sieve 30 is arranged as a classifying device.
The low-concentration slurry 8 containing pulverized coal and the low-concentration slurry 26 containing ultra-fine coal classified by the sieve 30 are supplied to an agitator 29 and subjected to sufficient preliminary mixing, and then partially dehydrated by a dehydrator 9. To be done.

Such premixing is performed by the kneader 10 and the agitator 1 which will be used later.
Facilitate mixing in 4.

In the above description, the pulverized coal 22 to be mixed with the pulverized coal 20 having a water content higher than that of the product slurry 15 does not necessarily have to be in a dry state. For example, the dried pulverized coal contains a small amount of water and an additive. Pulverized coal having a moisture content lower than that of the product slurry 15 may be added, for example, for humidification.

However, when the pulverized coal which is pulverized by the dry pulverization method and is in a substantially dry state is used as the pulverized coal 22, the required amount of the pulverized coal is the minimum, which is the most preferable.

There are no restrictions on the type and structure of the crusher, classifier, dehydrator, kneader, etc., the type and position of additives, the presence or absence of a deashing process, etc. It is also possible to provide a tank.

It is also possible to use coke as a part of the raw material coal.

Effect of the Invention As described above, the present invention is a method for producing a coal / water slurry for adding water to coal to process it into a pulverized coal slurry having a predetermined water content ratio, which is pulverized together with water to form a slurry of low concentration. Partial dehydration of the pulverized coal that has become a state in which it has a higher water content than the product slurry, and by mixing it with pulverized coal that has a lower water content than the product slurry, a product slurry with a predetermined concentration of coal and water is produced. Since it is a method for producing a coal / water slurry characterized by that, the amount of coal to be pulverized by the low-concentration wet pulverization method that minimizes the power required for pulverization per unit weight of coal, and the power required for pulverization is relatively high. It is possible to prevent excessive work in the dehydrator by effectively utilizing the pulverized coal pulverized by the dry pulverization method while keeping the amount of coal pulverized by the dry pulverization method to a necessary minimum. .

Therefore, it is possible to reduce the total power consumption required for the production of coal / water slurry.

[Brief description of drawings]

FIG. 1 is a system diagram of a manufacturing apparatus capable of carrying out a method for manufacturing coal / water slurry according to an embodiment of the present invention, and FIG.
Fig. 3 and Fig. 3 respectively show coal according to another embodiment of the present invention.
A system diagram of a manufacturing apparatus capable of carrying out the water slurry manufacturing method, and FIGS. 4 and 5 are system diagrams of manufacturing apparatuses capable of carrying out the conventional coal / water slurry manufacturing method, respectively. (Explanation of symbols) 1, 25 ...... Crusher, 2 ...... Coal 3, 7, 8, 26 ...... Low concentration slurry 4 ...... Water 6,27 ...... Wet classifier 9 ...... Dehydrator 10 ...... Kneader, 11 …… Adjusted water 12 …… Additive, 14, 29 …… Stirrer 15 …… Product slurry, 18 …… Crusher 20, 22 …… Pulverized coal 21 …… Pneumatic classifier 24 …… Storage Bottle, 28 ... Finishing crusher 30 ... Sieve.

Claims (4)

[Claims] 1. A method for producing a coal-water slurry for adding water to coal to process it into a slurry-like pulverized coal having a predetermined water content, wherein the pulverized coal is pulverized together with water to form a slurry slurry having a low concentration. Coal / water slurry characterized in that it is made into a state with more water than the product slurry by dehydration, and pulverized coal with less water than the product slurry is mixed with this to produce a coal / water slurry with a predetermined concentration. Manufacturing method. 2. The moisture ratio of the pulverized coal after the partial dehydration is 30.
The method for producing a coal / water slurry according to claim 1, wherein the amount is -40%. 3. The method for producing a coal / water slurry according to claim 1, wherein pulverized coal having a water content lower than that of the product slurry is dried. 4. The particle size of pulverized coal having a water content smaller than that of the product slurry is smaller than that of the partially dehydrated pulverized coal, according to any one of claims 1, 2 and 3. Method for producing coal / water slurry.