JPH07173476A - Production of high-concentration aqueous coal slurry - Google Patents

Abstract

PURPOSE:To efficiently obtain a high-concentration aqueous coal slurry excellent in ignitability and flammability by classifying a coal feedstock into coarse particles, small particles, and fine particles, pulverizing only the small particles with a low-concentration wet mill, and grinding the pulverized particles with a high-concentration wet mill along with the fine particles. CONSTITUTION:A coal feedstock is fed to a crusher 2 from a feedstock bunker 1. The crushed coal is introduced into a two-stage classifying apparatus 3, and classified into coarse particles 9a incapable of passing through the first classifier, small particles 9b which have passed through the first classifier but are incapable of passing through the second classifier, and fine particles 9d passed through the second classifier. The particles 9a are returned to the crusher 2 and recrushed. The particles 9b are introduced into a low-concentration wet mill 5 along with water and optionally with a surfactant 10 to wet-pulverize the particles 9b. The resulting slurry 9c is introduced into a high-concentration wet mill 6 along with the particles 9d and water and optionally with a surfactant 11 to pulverize the particles. The concentration of the slurry is then regulated. Thus, a high-concentration aqueous coal slurry is produced, which is stored in a slurry storage tank 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a high-concentration coal / water slurry.

[0002]

2. Description of the Related Art In a conventional method for producing a high-concentration coal / water slurry, raw coal is roughly crushed by a crusher, then charged into a wet mill together with water and a surfactant, and finely crushed to form a slurry. Such a conventional device is shown in FIG.
The method for producing the slurry will be described with reference to the drawings.

In FIG. 8, a coking coal is stored in a coking coal bunker 1 and supplied to a crusher 2 in a fixed amount.
The raw coal is roughly crushed by the coarse crusher 2, and the coarsely crushed raw coal is sent to the one-stage classifier 4 for classification.

In the one-stage classifier 4, coarse particles having a certain size or more are classified and returned to the crusher 2 again through a line 9a for recirculation and re-pulverized until the size becomes less than a certain size. Be crushed.

Coarse pulverized coal having a certain particle size or less is fed into the wet mill 7 after the water and the surfactant 10 are added before the wet mill 7 in the middle of the pipeline 9b. Then, after being finely pulverized by the wet mill 7 and made into a slurry, it is sent to the slurry storage tank 8.

[0006]

However, the conventional method for producing a coal / water slurry using such an apparatus has the following problems. That is, since the coal coarsely crushed by the single-stage classifier 4 has a large particle size and requires a long staying time in the wet mill 7, the wet mill 7 tends to be large.

For this reason, the power consumption of the wet mill and the equipment cost are high. When coarse particles are supplied to the wet mill 7, the coarse particles in the product slurry increase, and when the coarse particles are burned, the unburned content in the ash increases or burner chips are clogged. It will adversely affect sex.

Furthermore, in order to increase the concentration of the slurry, it is necessary to pack the coal particles in the closest packing, but there is a limit to the particle size adjustment with only one stage of the wet mill.

The present invention solves various problems and problems of the manufacturing method by such a conventional apparatus, reduces coarse particles,
It is intended to provide a method for producing a high-concentration coal / water slurry in which fine particles are increased to increase the concentration of the slurry and power is also reduced.

[0010]

Therefore, in the present invention, the raw coal is roughly crushed by a coarse crusher, and the coarse crushed coal is subjected to dry classification to obtain coarse particles,
Divide into fine and fine particles. The coarse particles are returned to the crusher and re-crushed. The fine particles are pulverized and slurried in a low-concentration wet mill, and then fed to a high-concentration wet mill together with the fine particles that have been classified before to prepare a slurry.

Further, in the above manufacturing method, the ratio of the openings of the two-stage classifier, the crushing concentration ratio in the low concentration and high concentration wet mills, and the weight and the high amount of coal contained in the slurry at the outlet of the low concentration wet mill. We also provide methods that specify the range of the ratio of fine particles to be added to the concentration wet mill, and in these methods, aim to reduce coarse particles and increase fine particles, and to increase the concentration of the slurry and reduce the power. To do.

That is, in the invention of claim 1, the coal coarsely crushed by the coarse crusher is classified by the two-stage classifier, and the coarse particles of the first-stage non-passage of the same classifier and the first-stage passage of the same classifier are passed. Divided into fine particles for the second-stage non-passage and fine particles for the second-stage passage of the same classifier, the coarse particles are returned to the coarse crusher and re-ground, and the fine particles are a low-concentration wet type. In a mill, mix with at least one of water and a surfactant and wet pulverize to form a slurry, and mix the slurry and the fine particles with at least one of water and a surfactant in a high-concentration wet mill. Provided is a method for producing a high-concentration coal / water slurry, which comprises pulverizing and adjusting a slurry.

The invention of claim 2 is the same as the invention of claim 1, wherein the ratio (S) of the first stage opening (S ₁ ) and the second stage opening (S ₂ ) of the two-stage classifier is ₁ / S ₂ ) is in the range of 1.5 to 6, and a method for producing a high-concentration coal / water slurry is provided.

[0014] Further, the invention of claim 3, in the invention of claim 1, wherein the low density wet mill grinding concentration (C _L) and pulverized concentration of the high concentration wet milling (C _H) and the ratio of (C _L /
A method for producing a high-concentration coal / water slurry, characterized in that C _H ) is in the range of 0.7 to 1.0.

Further, the invention of claim 4 is the invention of claim 1.
In the slurry of the low-concentration wet mill outlet in
Weight (W₁) And the weight of fine particles supplied to the high-concentration wet mill
(W ₂) And the ratio (W₁ / W₂) Is in the range of 0.4 to 2.4
The high-concentration coal / water soot according to claim 1, wherein
A method for manufacturing a rally is provided.

[0016]

According to the present invention, by taking such means, the coal coarsely crushed by the coarse crusher is classified into coarse particles, fine particles and fine particles by the two-stage classifier. Coarse particles are returned to the crusher and pulverized again, and fine particles are wet pulverized by a low-concentration wet mill to form a slurry, and this slurry and fine particles from the two-stage classifier are mixed and pulverized by a high-concentration wet mill to obtain a high concentration. Manufactures a coal / water slurry.

Therefore, the coarse particles in the coarsely crushed coal are re-pulverized, and only the fine particles are pulverized by the low-concentration wet mill, so that the coarse particles can be effectively reduced. In addition, the slurry and fine particles supplied to the high-concentration wet mill are being finely pulverized, so that the retention time in the same mill can be shortened, the high-concentration wet mill can be downsized, and the particle size distribution of fine particles can be reduced. Since it is adjusted, close packing is possible, and the coal / water slurry can be easily made to have a high concentration. Furthermore, since coarse particles are not included, coarse particles are not included in the product slurry at the outlet of the high-concentration wet mill, ignitability and combustibility are stabilized, and unburned matter in ash is reduced.

Further, in the invention of claim 2, in the invention of claim 1 described above, the ratio of the first stage opening (S ₁ ) and the second stage opening (S ₂ ) of the two-stage classifier ( S ₁ / S ₂ ) is 1.5 to
By setting it in the range of 6.0, the same effect as described above can be obtained, and the reduction of coarse particles and the increase of ultrafine particles are remarkably improved.

Further, in the invention of claim 3, the ratio (C _L / C _H ) of the grinding concentration (C _L ) of the low-concentration wet mill and the grinding concentration (C _H ) of the high-concentration wet mill is 0.7. By setting it in the range from 1.0 to 1.0, the same effect as that of the above-mentioned invention of claim 1 can be obtained, and the slurry concentration can be more stably maintained satisfactorily.

Further, in the invention of claim 4, the ratio of the weight of the coal (W ₁ ) in the slurry at the outlet of the low-concentration wet mill to the weight of fine particles (W ₂ ) supplied to the high-concentration wet mill (W ₁ /
By setting W ₂ ) in the range of 0.4 to 2.4, it is possible to obtain a good-quality slurry having the same effect as that of the above-mentioned invention of claim 1 and stable slurry concentration.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a system diagram of a method for producing a high-concentration coal / water slurry according to an embodiment of the present invention.

In FIG. 1, the coal supplied from the raw coal bunker 1 to the crusher 2 is roughly crushed. The coarse powder enters the second-stage classifier 3 through a pipe and is classified, and the coarse particles for the first-stage classifier do not pass, the fine particles for the first-stage classifier but the second-stage classifier do not pass, It is divided into fine particles that have passed through the second classifier. Coarse particles having a particle diameter of 3 mm or more among these classified coals are returned to the crusher 2 by the pipe line 9a and re-crushed.

The fine particles are fed into the low-concentration wet mill 5 together with water or water and the surfactant 10 through a line 9b,
Be crushed. The slurry thus produced goes to the high-concentration wet mill 6 through the pipe 9c, and is supplied to the high-concentration wet mill 6 along with the fine particles that have passed through the pipe 9d.

In the high-concentration wet mill 6, the slurry and fine particles and water or water and the surfactant 10 and the mixture are pulverized and slurried, adjusted, and then fed as a product slurry into the slurry storage tank 8 through a pipe 9e, Will be stored.

In such a coal / water slurry, it is necessary to reduce the coarse particles of the coal and increase the fine particles, and in order to reduce the coarse particles,
It is desirable to feed coal of 3 mm or less into the wet mill. Therefore, in the present invention, classification is performed by the two-stage classifier 3 to divide into coarse particles, fine particles, and fine particles. The fine particles are pulverized by the low-concentration wet mill 5 that has the effect of reducing coarse particles, and the fine particles are put into the high-concentration wet mill 6 that has the effect of increasing ultrafine particles. However, since the high-concentration wet mill 6 is not very effective in reducing coarse particles, if coarse particles enter, the coarse particles in the product may increase. When the ratio S (S ₁ / S ₂ ) of the _first stage opening (S ₁ ) and the second stage opening (S ₂ ) of the classifier 3 becomes 1.5 or more, the effect of reducing coarse particles in the wet mill increases. It was confirmed. Furthermore, it was confirmed that the effect of increasing the ultrafine particles was saturated when the S was 6.0 or more. Therefore, the range of S is almost
It is preferably 1.5 to 6.

FIG. 2 shows the results of the experiment. The ratio of the openings (S ₁ / S ₂ ) of the two-stage classifier is shown on the horizontal axis, the amount of coarse particles (%) on the left vertical axis, and the amount of ultrafine particles. (%) Is shown on the right vertical axis,
A shown by a solid line is a curve of the amount of coarse particles, and a dotted line B is a curve of the amount of ultrafine particles. The coarse particles start to decrease before and after S = 1.5, and the amount of fine particles increases before and after S = 6.0. The trend is beginning to saturate.

Further, as described above, crushing in a low-concentration wet mill is effective in reducing coarse particles, and crushing in a high-concentration wet mill is confirmed to be effective in increasing ultrafine particles. The ratio of the concentrations is such that the grinding concentration in the low-concentration wet mill is C _L and the high-concentration grinding concentration is C _H , and the ratio C = C _L /
When C _H is taken, the stability of the coal / water slurry is best when the value of C is approximately 0.7 to 1.0.

FIG. 3 shows the results of the experiment, in which C = C _L / C _H is plotted on the horizontal axis and static stability (days) is plotted on the vertical axis. Stability is saturated,
This state continues until C = 1.0. The stationary stability means the number of days during which the slurry and the coal mixed state of the slurry maintains a uniform concentration state, and when C is in the range of approximately 0.7 to 1.0, the number of days in the stable state is the maximum state. Can be maintained at.

Regarding the amount of coal charged into the wet mill, the weight (W ₁ ) of the coal in the slurry at the outlet of the low-concentration wet mill 5 and the fine particles (W ₂ ) mixed with this and charged into the high-concentration wet mill 6 are used. ) And the ratio is too large or too small, a high-quality high-concentration coal / water slurry cannot be obtained, and the ratio W = W ₁ / W ₂
It was found that a high-quality high-concentration coal / water slurry can be obtained when is about 0.4 to 2.4.

FIG. 4 shows the result of the experiment. As described above, the static stability (days) of a high-quality high-concentration coal / water slurry which is stable when W is in the range of 0.4 to 2.4. ) Can be held for a long time.

In the examples having the characteristics described above, fine particles having a large proportion of coarse particles are first pulverized by the low-concentration wet mill 5 to reduce the coarse particles to a large extent, and then Is a method for producing a high-concentration coal / water slurry in which water or water and a surfactant are added and the mixture is pulverized in a high-concentration wet mill 6 to increase the generation rate of ultrafine particles. Was carried out.

As a result, by combining the effect of reducing coarse particles in the low-concentration wet crushing and the effect of increasing the ultrafine particles in the high-concentration wet crushing, which is the aim of the present invention, it has succeeded in achieving an appropriate particle size distribution. .

FIG. 5 shows the particle size and the cumulative ratio (particle size distribution of the pulverized product) in the low-concentration wet mill. In the low-concentration wet pulverization, the particle size distribution of the pulverized product has a steep slope, and the effect of reducing coarse particles is extremely high. It can be seen that the ultrafine particle generation ratio is small although it is very large.

FIG. 6 shows the particle size and the cumulative ratio (grind particle size distribution) in the high-concentration wet mill. In high-concentration wet grinding, the particle size distribution of the crushed product becomes a gentle gradient, and the ultrafine particle generation effect is obtained. Is very large, but it can be seen that the ratio of coarse particles is large.

FIG. 7 shows the particle size and cumulative ratio of the present invention when two-stage grinding by a two-stage classifier, a low-concentration wet mill and a high-concentration wet mill are used. The low-concentration wet mill shown in FIG. This is a characteristic that has both the effect of reducing coarse particles in Fig. 7 and the effect of generating ultrafine particles in the high-concentration wet mill shown in Fig. 7.

Next, the test results are shown in Table 1. Compared with the conventional high-concentration wet one-step pulverization method, the concentration can be increased by about 1% with substantially the same slurry viscosity, and the coarse particle amount (500 μm or more).
It has been revealed that the power consumption can be reduced to about 1/5 and the power consumption of the mill can be reduced by 20% or more.

[0037]

[Table 1]

[0038]

As described above in detail, according to the method of the present invention, coal is classified into coarse particles, fine particles, and fine particles, and only the fine particles are crushed by a low-concentration wet mill to obtain a high concentration. It is a method of sending to a wet mill, mixing with fine particles in a high-concentration wet mill and pulverizing to adjust the slurry, so that the effect of reducing coarse particles is increased and the effect of forming ultrafine particles is also increased, so that it is possible to increase the concentration of the slurry. it can. Furthermore, the retention time in the mill is shortened by making the fine particles fine, the mill can be made smaller and the power is also reduced, and since the product slurry does not contain coarse particles, the ignitability and combustibility are improved. It is stable, the unburned content is reduced, and the product quality is improved.

Further, the opening ratio of the classifier, the ratio of the grinding concentration of the low-concentration wet mill and the grinding concentration of the high-concentration wet mill, the weight of coal in the slurry from the low-concentration wet mill and the high-concentration wet mill are added. By setting the ratio with respect to the weight of the fine particles within a specific range, the above effect can be made more effective.

[Brief description of drawings]

FIG. 1 is a systematic diagram of an apparatus to which a method for producing high-concentration coal / water slurry according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing characteristics of a mesh ratio and a particle amount of a two-stage classifier in one example of the present invention.

FIG. 3 is a diagram showing characteristics of concentration ratio and static stability in one example of the present invention.

FIG. 4 is a diagram showing the characteristics of the weight ratio of coal charged in a mill and the stationary stability in one example of the present invention.

FIG. 5 is a diagram showing a relationship between a particle size and a cumulative ratio only in a low-concentration wet mill in one example of the present invention.

FIG. 6 is a diagram showing a relationship between a particle size and a cumulative ratio only in the high-concentration wet mill in one example of the present invention.

FIG. 7 is a diagram showing the relationship between the total particle size and the cumulative ratio in one example of the present invention.

FIG. 8 is a system diagram of a conventional high-concentration coal / water slurry manufacturing apparatus.

[Explanation of symbols]

 1 Coking coal bunker 2 Crusher 3 Two-stage classifier 5 Low-concentration wet mill 6 High-concentration wet mill 8 Slurry storage tank

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hirohisa Yoshida 5-717-1, Fukahori-cho, Nagasaki City Mitsubishi Heavy Industries Ltd. Nagasaki Research Institute

Claims (4)

[Claims] 1. Coal coarsely crushed by a coarse crusher is classified by a two-stage classifier, and coarse particles of the first stage non-passage of the same classifier, and second stage of the first stage passage of the same classifier. Fine particles of non-passage,
Separated into fine particles for the second pass of the same classifier, the coarse particles are returned to the coarse crusher and re-pulverized, and the fine particles are mixed with at least one of water and a surfactant in a low-concentration wet mill. Wet pulverizing to form a slurry, and the slurry and the fine particles are mixed with at least one of water and a surfactant, pulverized with a high-concentration wet mill, and slurry adjustment is performed. -Method for producing water slurry. 2. The first stage opening (S ₁ ) of the two-stage classifier
When the second stage of the mesh ratio of the _{(S 2) (S 1 /} S 2) 1.5
The method for producing a high-concentration coal / water slurry according to claim 1, wherein the method is in the range of 6 to 6. 3. The grinding concentration (C _L ) of the low-concentration wet mill
And the grinding concentration (C _H ) of the high-concentration wet mill (C _L).
/ C _H) are provided methods for producing high-concentration coal-water slurry according to claim 1, wherein in the range of 0.7 to 1.0. 4. The ratio (W ₁ / W ₂ ) of the weight (W ₁ ) of coal in the slurry at the outlet of the low-concentration wet mill and the weight (W ₂ ) of fine particles supplied to the high-concentration wet mill is 0. The high-concentration coal according to claim 1, which is in the range of 4 to 2.4.
Method for producing water slurry.