JP2902286B2 - Production method of high concentration coal / water slurry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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 crushed by a crusher, and then charged into a wet mill together with water and a surfactant, and finely crushed to form a slurry. Such a conventional apparatus is shown in FIG.
The method for producing the slurry will be described with reference to the drawings.

[0003] In FIG. 8, coking coal is stored in a coking coal bunker 1 and supplied to a crusher 2 at a constant rate.
The raw coal is crushed by the crusher 2 and the crushed raw coal is sent to the single-stage classifier 4 to be classified.

In the single-stage classifier 4, coarse particles having a certain particle size or more are classified, returned to the crusher 2 again through a pipe 9a for recirculation, and crushed again until the particles have a certain particle size or less. Crushed.

[0005] Coarse coal having a particle diameter of less than a certain value is fed into the wet mill 7 after adding water and a surfactant 10 before the wet mill 7 in the middle of the pipe 9b. Then, after being pulverized by a wet mill 7 to form a slurry, the slurry is sent to a slurry storage tank 8.

[0006]

However, the method of producing a coal / water slurry using such a conventional 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 residence time in the wet mill 7, the wet mill 7 tends to be large.

For this reason, the power consumption and equipment cost of the wet mill have been high. Also, when the coarse particles are supplied to the wet mill 7, the coarse particles in the product slurry increase, and when this is burned, the unburned ash in the ash increases, and the burner chips are clogged. Adversely affect sex.

Further, in order to increase the concentration of the slurry, it is necessary to pack coal particles in a close-packed manner. However, there is a limit to the particle size adjustment using only one stage of a wet mill.

The present invention has been made to solve the problems and problems of the manufacturing method using such a conventional apparatus, to reduce coarse particles,
An object of the present invention is to provide a method for producing a high-concentration coal / water slurry in which the number of fine particles is increased to increase the concentration of the slurry and the power is reduced.

[0010]

Accordingly, in the present invention, the raw coal is crushed by a crusher, and the crushed coal is dry-classified to obtain coarse particles.
Divide into fine grains and fine grains. The coarse particles are returned to the crusher and a means for re-crushing is used. The fine particles are pulverized and slurried in a low-concentration wet mill, and then supplied to a high-concentration wet mill together with the fine particles previously classified to form a slurry.

In the above-mentioned production method, the ratio of the opening of the two-stage classifier, the ratio of the pulverization concentration in the low-concentration and high-concentration wet mills, and the weight and highness of the coal contained in the slurry at the outlet of the low-concentration wet mill are also considered. Also provided are methods that specify the range of the ratio of fine particles to be added to the concentration wet mill.In these methods, methods to reduce coarse particles and increase fine particles, to increase the concentration of the slurry and to reduce the power as well Is what you do.

That is, according to the first aspect of the present invention, the coal coarsely pulverized by the crusher is classified by the two-stage classifier, and the coarse particles that cannot pass through the first stage of the classifier and the first stage of the same classifier are passed. And the fine particles of the second pass through the same classifier are divided into fine particles of the second pass and fine particles of the second pass through the same classifier, and the coarse particles are returned to the crusher and crushed again. The mixture is mixed with at least one of water and a surfactant in a mill and wet-pulverized to form a slurry. The slurry and the fine particles are mixed with at least one of water and a surfactant and mixed in a high-concentration wet mill. Provided is a method for producing a high-concentration coal / water slurry characterized by performing pulverization and slurry adjustment.

Further, according to the invention of claim 2, in the invention of claim 1, the ratio (S ₁ ) between the first opening (S ₁ ) and the second opening (S ₂ ) of the first stage of the two-stage classifier is provided. 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, wherein 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 low concentration wet mill exit slurry in the slurry
Weight (W₁) And the weight of the fine particles supplied to the high-concentration wet mill
(W _Two) And the ratio (W₁ / W_Two) Is in the range of 0.4 to 2.4
2. The high-concentration coal / water stream according to claim 1, wherein
Provided is a method for manufacturing a rally.

[0016]

According to the first aspect of the present invention, in the present invention, the coarsely pulverized coal is classified into coarse, fine and fine particles by a two-stage classifier. The coarse particles are returned to the crusher and re-milled, and the fine particles are wet-milled in a low-concentration wet mill to form a slurry. To produce coal and water slurry.

Therefore, the coarse particles in the coarse coal are pulverized again, 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 finely pulverized, so that the residence time in the mill can be reduced, the capacity of the high-concentration wet mill can be reduced, and the particle size distribution of the fine particles can be reduced. Is adjusted, close packing is possible, and the concentration of coal / water slurry can be easily increased. Further, since coarse particles are not contained, coarse particles are not contained in the product slurry at the outlet of the high-concentration wet mill, the ignitable combustion property is stabilized, and the unburned ash content is reduced.

According to the second aspect of the present invention, in the first aspect of the present invention, the ratio (S ₁ ) of the first stage opening (S ₁ ) to the second stage opening (S ₂ ) of the two-stage classifier is determined. S ₁ / S ₂ ) is 1.5 to
When the content is in the range of 6.0, the same action as described above is achieved, and the reduction of coarse particles and the increase of ultrafine particles are significantly improved.

According to the third aspect of the present invention, the ratio (C _L / C _H ) of the pulverization concentration (C _L ) of the low concentration wet mill to the pulverization concentration (C _H ) of the high concentration wet mill is 0.7. When the content is in the range of 1.0 to 1.0, the same action as the above-described claim 1 can be obtained, and the slurry concentration can be more stably maintained.

Furthermore, in the invention of claim 4, the ratio (W ₁ / W) of the weight of coal (W ₁ ) 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 obtained.
By setting W ₂ ) in the range of 0.4 to 2.4, the same action as that of the first aspect of the present invention can be obtained, and a high-quality slurry having a stable slurry concentration can be obtained.

[0021]

Embodiments of the present invention will be described below 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 one embodiment of the present invention.

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

The fine granules are fed into the low-concentration wet mill 5 together with water or water and a surfactant 10 through a pipe 9b,
Crushed. The slurry thus formed travels through the pipe 9c to the high-concentration wet mill 6, but is supplied to the high-concentration wet mill 6 while being combined with the fine particles passing through the pipe 9d.

In the high-concentration wet mill 6, the mixture of the slurry and the fine particles, water or water and the surfactant 10 is pulverized, slurried, adjusted, and sent as a product slurry to the slurry storage tank 8 through a pipe 9e. It will be stored.

In such a coal / water slurry, it is necessary to reduce the coarse particles and increase the fine particles of the coal.
It is desirable to feed coal of 3 mm or less into a wet mill. For this purpose, in the present invention, the mixture is classified by the two-stage classifier 3 and divided into coarse particles, fine particles, and fine particles. Fine particles are pulverized by a low concentration wet mill 5 having an effect of reducing coarse particles, and fine particles are introduced into a high concentration wet mill 6 having an effect of increasing ultrafine particles. However, since the high-concentration wet mill 6 is not so effective in reducing coarse particles, the presence of coarse particles may increase the number of coarse particles in the product. When the ratio S (S ₁ / S ₂ ) between the _first opening (S ₁ ) and the second opening (S ₂ ) of the classifier 3 is 1.5 or more, the effect of reducing coarse particles in the wet mill increases. It was confirmed. Furthermore, it was also confirmed that when the S was 6.0 or more, the effect of increasing ultrafine particles was saturated. Therefore, the range of S is approximately
It is preferably from 1.5 to 6.

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

As described above, it has been confirmed by tests that pulverization with a low-concentration wet mill is effective in reducing coarse particles and pulverization in a high-concentration wet mill is effective in increasing ultrafine particles. Assuming that the concentration ratio of the low-concentration wet mill is C _L and the high-concentration pulverization concentration is C _H , the ratio C = C _L /
Taking C _H , the stability of the coal / water slurry is best when the value of C is approximately 0.7 to 1.0.

[0028] FIG. 3 shows the experimental results, the horizontal axis C = C _L / C _H, takes a standing stability (days) on the vertical axis, left to stand at around the C = 0.7 Stability becomes saturated,
This state continues until C = 1.0. Stationary stability refers to the number of days that the slurry mixture of coal and water maintains a uniform concentration state. When C is in the range of approximately 0.7 to 1.0, the number of days in the stable state is maximized. Can be maintained.

With respect to the amount of coal fed 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 fed into the high-concentration wet mill 6 ) Is too large or too small to produce a high-quality high-concentration coal / water slurry, and the ratio W = W ₁ / W ₂
It was found that a high-quality high-concentration coal / water slurry could be obtained when the ratio was approximately 0.4 to 2.4.

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

In the embodiment having the features specifically described above, the fine grains having a high coarse grain ratio are firstly pulverized by the low-concentration wet mill 5 to greatly reduce the coarse grains first. This is a method for producing a high-concentration coal / water slurry in which the ratio of ultrafine particles is increased by adding fine particles to water, and further adding water or water and a surfactant, and pulverizing with a high-concentration wet mill 6. Was carried out.

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

FIG. 5 shows the particle size and the cumulative ratio (particle size distribution) of the low-concentration wet mill. In the low-concentration wet milling, the particle size distribution of the pulverized material becomes steep, and the effect of reducing coarse particles is extremely large. It can be seen that the ratio of generation of ultrafine particles is small.

FIG. 6 shows the particle size and the cumulative ratio (pulverized product particle size distribution) in a high-concentration wet mill. Is very large, but the ratio of coarse particles is large.

FIG. 7 shows the particle size and the cumulative ratio of the present invention when a two-stage pulverizer using a two-stage classifier, a low-concentration wet mill and a high-concentration wet mill are used. The characteristics of the present invention have both the effect of reducing coarse particles by the method and the effect of generating ultrafine particles by the high-concentration wet mill shown in FIG.

Next, the test results are shown in Table 1. As compared with the conventional high-concentration wet single-stage pulverization method, the concentration can be increased by about 1% with almost the same slurry viscosity, and the amount of coarse particles (500 μm or more)
It has been found that the power consumption of the mill can be reduced by about one fifth and the power consumption of the mill can be reduced by more than 20%.

[0037]

[Table 1]

[0038]

As described above, according to the method of the present invention, 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 pulverized by a low-concentration wet mill to obtain a high-concentration coal. It is a method of mixing with fine particles in a high-concentration wet mill and pulverizing the slurry by grinding it into a wet mill, so that the effect of reducing coarse particles increases and the effect of generating ultrafine particles also increases, making it possible to increase the concentration of slurry. it can. Furthermore, the residence time in the mill is shortened by pulverization of fine particles, the size of the mill can be reduced, and the power is also reduced.Since the product slurry does not contain coarse particles, the ignitability and flammability are improved. It is stable, reduces unburned components, and improves product quality.

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

[Brief description of the drawings]

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

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

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

FIG. 4 is a view showing characteristics of a weight ratio of coal fed into a mill and a stationary stability in one embodiment of the present invention.

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

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

FIG. 7 is a diagram showing the relationship between the overall 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 production 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

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hirohisa Yoshida 5-717-1 Fukahori-cho, Nagasaki-shi Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory (56) References JP-A-1-178595 (JP, A) JP-A-63-23992 (JP, A) JP-A-62-132999 (JP, A) JP-A-62-70490 (JP, A) JP-A-60-215096 (JP, A) JP-A-60-58493 (JP, A) , A) JP-A-59-49291 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10L 1/32

Claims (4)

(57) [Claims] 1. Coal coarsely pulverized by a crusher is classified by a second-stage classifier, and coarse particles that are not passed through the first stage of the classifier and second-stage that are passed through the first stage of the same classifier. Fine granules for non-passage,
The coarse particles are separated into fine particles of the second pass through the classifier, the coarse particles are returned to the crusher and reground, and the fine particles are mixed with at least one of water and a surfactant in a low-concentration wet mill. A high-concentration coal characterized by mixing the slurry and the fine particles with at least one of water and a surfactant and pulverizing the mixture with a high-concentration wet mill to prepare a slurry. -A method for producing a water slurry. 2. The first opening of the two-stage classifier (S ₁ ).
And the ratio (S ₁ / S ₂ ) of the second stage opening (S ₂ ) to 1.5
The method for producing a high-concentration coal / water slurry according to claim 1, wherein the slurry is in a range of from 6 to 6. 3. The grinding concentration (C _L ) of the low-concentration wet mill.
(C _L ) of the pulverization concentration (C _H ) of the high-concentration wet mill
The method for producing a high-concentration coal / water slurry according to claim 1, wherein / C _H ) is in the range of 0.7 to 1.0. 4. The ratio (W ₁ / W ₂ ) of the weight of 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 is 0. The high-concentration coal according to claim 1, wherein the high-concentration coal is in a range of 4 to 2.4.
Water slurry production method.