JPS63172789A - Production of coal-water slurry - Google Patents

Abstract

PURPOSE:To attain a reduction in the whole power consumption required for producing a coal slurry, by mixing a pulverized coal slurry having a water content larger than that of a product slurry with a pulverized coal having a water content smaller than that of the product slurry in such proportions as will provide a predetermined concn. CONSTITUTION:A low-concn., slurry-form pulverized coal is prepd., with the power required for pulverization per unit coal wt. kept low, by pulverizing coal together with water. Then, a pulverized coal having a water content larger than that of a product slurry is prepd. by partially dehydrating the low-concn., slurry-form pulverized coal. Further, the pulverized coal is mixed with a small amt. of pulverized coal which has a water content smaller than that of the product slurry and which is prepd. by separately pulverizing coal, thereby preparing a coal-water slurry having a predetermined concn. As a result, the amt. of coal pulverized according to the low-concn. wet pulverization technique enabling minimization of the power required for pulverization per unit coal wt. is maximized, and the amt. of coal pulverized according to the dry pulverization technique requiring a relatively larger power for pulverization is minimized. Thus, effective utilization of a pulverized coal pulverized according to the dry pulverization technique is attained.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for producing a coal/water slurry, and more particularly, to a method for adjusting the moisture ratio for adding water to coal and processing it into slurry-like pulverized coal. be.

BACKGROUND OF THE INVENTION In recent years, coal is easy to transport and store, and can be used in the same way as heavy oil when combusted. Coal/water mixed fuel (foaming agent, etc.) mixed into a slurry
Attempts are being made to use water slurry).

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

In other words, pulverized coal needs to be distributed over a wide range in terms of particle size, and not only does it have a range of particle sizes from large to minute, but in order to increase the packing density, it is necessary to vary the variety of coal used. Although it depends on the situation, a very large amount of ultrafine coal of less than 3 μm is required, for example, 3 to 15%.

The method for producing coal/water slurry that meets these conditions includes:
Hitherto, it has been known that they can be roughly divided into high-concentration wet pulverization systems and low-concentration wet pulverization systems.

The high-concentration wet pulverization method described above supplies coal, additives, and the amount of water necessary for the product slurry to the pulverizer in advance, pulverizes it, and then discharges the product slurry directly from the pulverizer, which simplifies the equipment configuration. It also has the advantage of not requiring dehydration and mixing steps like the low-concentration wet pulverization method described below, but the power required for pulverization per unit coal weight is large, and
Since a highly concentrated product slurry is obtained directly from the pulverizer, it is impossible to classify the product slurry, and therefore 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. It is ground using water 4 to form a low concentration slurry 3. Note that the coal concentration in this case is approximately 30%.

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

The low-concentration slurry 7 containing coarse pulverized coal is returned to the pulverizer 1 and re-pulverized, while the low-concentration slurry 8 containing pulverized coal is dehydrated in a dehydrator 9 and turned into a cake-like form. Water 11. and are kneaded together with additives 12 in a kneader 10,
A highly concentrated slurry 13 having a predetermined moisture content is obtained.

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

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

According to the above-described low-concentration wet pulverization method, the power required in the pulverizer 1 is relatively small, and the low-concentration slurry 3 discharged from the pulverizer 1 is classified after adding water as necessary.
Since the coarse pulverized coal contained in the low concentration slurry 3 can be re-pulverized, it is easy to adjust the particle size distribution structure of the pulverized coal in the product slurry 15, and furthermore, a deashing step can be incorporated as necessary. It has the following advantages.

However, since a vacuum type or press type filter is generally used as the dehydrator 9, it is not possible to adjust the moisture content of the cake after dehydration to a constant value.
In the dehydrator 9, the water content is lowered to a level lower than that contained in the product slurry 15, and then the water content is lowered to a level lower than that contained in the product slurry 15.
At 0, it is necessary to supply a small amount of water 11 again to adjust the moisture to a predetermined level.

In particular, as mentioned above, the product slurry 15 needs to have a high concentration of about 65 to 80%, that is, a low moisture content of about 20 to 35%, and in order to reduce the moisture content to an even lower level in the dehydrator 9, , a lot of power is required.

After that, adjusting water 11 was added again and kneaded.

Since even more power is consumed during the stirring stage, the power required by the pulverizer itself is far less than that of the high-concentration pulverization method, but the power required for the entire coal/water slurry production system is higher than that of the high-concentration pulverization method. It will remain almost unchanged.

Furthermore, a large amount of equipment costs are required for hydrophilicity, crosstalk, and stirring steps.

Therefore, as shown in FIG. 5, it has been proposed to mix dry pulverized coal 17 into the low-concentration slurry 3 discharged from the pulverizer 1, thereby omitting the hydrophilization and crosstalk steps.

That is, in the pulverizer 1 to which coal 2 and water 4 were supplied, a low concentration slurry 3 was produced as in the case of the low concentration wet pulverization method shown in FIG. 4, and on the other hand, only coal 2 was supplied. Another pulverizer 18 produces dry pulverized coal 17 using a so-called dry pulverization method.

After that, the low concentration slurry 3 and the pulverized coal 17 are mixed with the additive 1.
Coal/water product slurry 15 having predetermined fluidity and concentration is produced by mixing and stirring with agitator 14.

However, the low concentration slurry 3 requires a large amount of dry pulverized coal 17. 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 the case of
More than 80% of the total amount of coal needs to be supplied in dry form.

However, the dry pulverization method, which grinds coal into dry pulverized coal, requires more power for pulverization per unit weight of coal than the wet pulverization method, and the overall power required is higher than that of the re-grinding method, as described above. It will remain almost unchanged.

Purpose of the Invention The present invention was devised in view of the above circumstances, and aims to provide a method for producing coal/water slurry that can reduce the overall power consumption required for producing coal/water slurry. This is the purpose.

Structure of the Invention In order to achieve the above object, the main means adopted by the present invention is to create a coal/water slurry for adding water to coal and processing it into slurry-like pulverized coal with a predetermined moisture ratio. In the production method, pulverized coal is pulverized with water to form a low-concentration slurry, which is partially dehydrated to form a state with more water than the product slurry, and pulverized coal with less water than the product slurry is mixed with this. This is a method for producing a coal/water slurry in which a coal/water slurry having a predetermined concentration is produced by:

Effect of the Invention By pulverizing coal with water, pulverized coal in the form of a low-concentration slurry is produced while keeping the power required for pulverization per unit coal weight low, and furthermore, the pulverized coal in the form of a low-concentration slurry is produced. By partially dehydrating the pulverized coal, it is made into pulverized coal that has a higher moisture content than the product slurry.

Then, a coal/water slurry having a predetermined concentration is produced by mixing this pulverized coal with a small amount of pulverized coal containing less moisture than a product slurry obtained by separately pulverizing coal.

EXAMPLES Hereinafter, examples embodying the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

It should be noted that the following examples are examples embodying the present invention, and are not intended to limit the technical scope of the present invention.

Here, 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,
FIGS. 2 and 3 are system diagrams of manufacturing equipment capable of implementing a method for manufacturing coal/water slurry according to another embodiment of the present invention, respectively.

Further, the same reference numerals will be used for the same elements as in the conventional method for producing coal/water slurry explained based on the production apparatus shown in FIGS. 4 and 5.

In the method for producing coal/water slurry according to this example, the first
As shown in the figure, most of the coal 2 is used in the pulverizer 1 to form a product slurry that is separately supplied to the pulverizer 1, as in the case of the conventional low-concentration wet pulverization method (see FIG. 4). The slurry 3 is milled using a larger amount of water 4 than the amount used in the slurry 3. In this case, by adjusting the coal concentration to approximately 30%, the power required 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 water 5 is added for classification, the mixture is supplied to a wet classifier 6, where a low concentration slurry 7 containing coarse powder coal and a low concentration slurry containing pulverized coal (pulverized coal in the form of a low concentration slurry) 8
It is classified into.

The low-concentration slurry 7 containing coarse pulverized coal is returned to the pulverizer 1 and re-pulverized, while the low-concentration slurry 8 containing pulverized coal is partially dehydrated in a dehydrator 9 to form a cake containing more water than the product slurry. Or it becomes slurry-like pulverized coal 20. In this case, the moisture ratio in the pulverized coal 20 is kept at a level slightly higher than the moisture ratio in the product slurry 15, which will be described later, for example, around 35%. Dehydration work in the dehydrator 9 with the moisture ratio after hydrophilization of 30 to 40% is relatively easy, although it depends on the particle size distribution and water absorption of the pulverized coal, so it is possible to downsize the dehydrator. In addition, less power is required for dewatering.

On the other hand, a portion of the coal 2 is pulverized by a pulverizer 18 using a dry pulverization method using a closed circuit, and is supplied to a pneumatic classifier 21 .

The coarse pulverized coal 23 classified by the pneumatic classifier 21 is returned to the pulverizer 18 and re-pulverized, while the pulverized coal is stored in a storage bin 24 as pulverized coal 22 with less moisture than the product slurry 15.
can be stored in

The pulverized coal 20 from the dehydrator 9 and the pulverized coal 22 cut out from the storage bin 24 in a predetermined ratio are blended in a predetermined ratio, and the additives 12 are added thereto and the mixture is sufficiently mixed in the kneader 10 and/or the stirrer 14. By mixing and stirring, a coal/water slurry 15 of a predetermined concentration is manufactured.

At this time, since the pulverized coal 20 from the dehydrator 9 has been dehydrated to a moisture level slightly higher than the moisture ratio in the product slurry 15 as described above, The amount of pulverized coal 22 in a dry state is only a small amount compared to the pulverized coal 20 described above.

For example, when producing a product slurry 15 with a concentration of 70% using a cake-like pulverized coal 20 with a water content of 35%, a dry slurry 15 of about 1/4 of the amount of pulverized coal in the cake-like pulverized coal 20 is used. It is sufficient to have the pulverized coal 22, and it is sufficient to mix approximately 175% of the total amount of coal in the product slurry 15 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, and the increase in the required pulverization power can be minimized. It is preferable from the viewpoint of safety that the amount of charcoal 22 handled is small.

However, the moisture ratio of the above pulverized coal 20 after partial hydrophilization is 40%.
If it exceeds this, the required amount of pulverized coal 22 in a dry state increases rapidly, so the moisture ratio of pulverized coal 20 should be kept below this.

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

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

In addition, the amount of coal that needs to be pulverized by the dry pulverization method is the amount that is passed through to produce the ultra-fine coal that constitutes the product slurry, and as shown in the first diagram, a classifier 2゛1 is installed,
The closed circuit system can be said to be an apparatus that has been used to produce ultra-fine coal on an industrial scale.

FIG. 2 shows a second embodiment of the present invention, and only the differences from the first embodiment described above will be explained below.

In this case, in order to produce the ultrafine coal constituting the product slurry 15 by a low concentration wet pulverization method, two wet pulverizers
．． 25 and wet classifiers 6 and 27 are arranged, and the crusher 25 produces a low concentration slurry 26 containing ultra-fine coal. A portion of the slurry 7 is supplied.

The low-concentration slurry 8 containing pulverized coal and the low-concentration slurry 26 containing ultra-pulverized coal described above are then supplied to a common dehydrator 9, where they are partially dehydrated in a premixed state and become a cake-like pulverized coal 20. .

On the other hand, a part of the coal 2 is passed through a crusher 18 using a dry crushing method.
The coal is pulverized into pulverized coal 22 of normal particle size. For this reason,
This dry pulverization can also be performed by an open circuit pulverization method as shown.

The pulverized coal 20.22 is added to the mixer 10 together with the additive 12.
After being kneaded in the slurry with a predetermined concentration, it is finished in a pulverizer 28.
The product slurry 15 is supplied to the finishing mill 28 for final particle size adjustment and thorough stirring.
becomes.

Furthermore, FIG. 3 shows a third embodiment according to the present invention, which is similar to the first embodiment described above. Only the differences from the second embodiment will be explained below.

At the outlet of the wet crusher 1 for crushing most of the coal 2, a mechanical classifier 1i30 is arranged. The low concentration slurry 8 containing pulverized coal classified in iii #30 and the low concentration slurry 26 containing ultrafine coal are mixed into the stirrer 2.
After being sufficiently premixed, it is partially dehydrated in a dehydrator 9.

Such premixing is performed in the subsequent mixer 10 and agitator 1.
4 to facilitate mixing.

In the above explanation, the pulverized coal 22 to be mixed with the pulverized coal 20 having a higher water content than the product slurry 15 does not necessarily have to be in a dry state. It is sufficient if the pulverized coal has a lower water content than product slurry 15, such as by adding and humidifying it.

However, when pulverized coal in a substantially dry state that has been pulverized by a dry pulverization method is used as the pulverized coal 22, it is most preferable because the amount required is minimal.

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

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

Effects of the Invention As described above, the present invention provides a method for producing a coal/water slurry in which water is added to coal to process it into slurry-like pulverized coal with a predetermined moisture ratio. By partially dehydrating the resulting pulverized coal, it becomes a state with more water than the product slurry, and by mixing this with pulverized coal, which has less water than the product slurry, a product slurry of coal and water with a predetermined concentration is produced. Since this is a method for producing a coal/water slurry characterized by While the amount of coal pulverized by the dry pulverization method is kept to the necessary minimum, the pulverized coal pulverized by the dry pulverization method can be effectively utilized to prevent excessive work in the dehydrator.

Therefore, it is possible to reduce the overall power consumption required for producing the coal/water slurry.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a production apparatus capable of carrying out the method for producing coal/water slurry according to one embodiment of the present invention, and FIGS. - Systematic diagram of manufacturing equipment that can carry out the water slurry manufacturing method. Figures 4 and 5 are system diagrams of manufacturing equipment that can implement the conventional coal-water slurry manufacturing method, respectively. (Explanation of symbols) l, 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...Additives
14.29...Agitator 15...Product slurry 18...Crusher 20.22...Pulverized coal 21...Air classifier 24...Storage bin 2nd...Finishing crusher 30
...sieve. Trainee: Kobe Steel, Ltd.

Claims (1)

[Claims] 1. In a method for producing a coal/water slurry for adding water to coal and processing it into slurry-like pulverized coal with a predetermined moisture ratio, the pulverized powder is pulverized together with water to form a low-concentration slurry. Coal characterized by partially dehydrating the charcoal to make it have a higher moisture content than the product slurry, and mixing this with pulverized coal that has less moisture content than the product slurry to produce a coal/water slurry with a predetermined concentration.・Method for producing water slurry. 2. After the above partial dehydration, the moisture ratio of the pulverized coal is 30 to 40%.
A method for producing a coal/water slurry according to claim 1. 3. The method for producing a coal/water slurry according to claim 1 or 2, wherein pulverized coal having a lower water content than the product slurry is dried. 4. The coal/water according to any one of claims 1, 2, or 3, wherein the particle size of the pulverized coal that has less moisture than the product slurry is smaller than the particle size of the partially dehydrated pulverized coal. Slurry manufacturing method.