JPS60158295A - Method and apparatus for producing concentrated coal/ water slurry - Google Patents

Abstract

PURPOSE:To obtain a highly stable conc. coal/water slurry, by mixing coal, water and a dispersant in a ball mill and passing the resulting slurry through a disc mill to reduce the max. particle size of coal in the slurry to a size within a specified range. CONSTITUTION:Coal is fed from a constant feeder 6 to a ball mill 8 at a predetermined feed rate, and at the same time, a mixture of water and a dispersant is fed from a water feeding tank 7 to the ball mill by means of a constant delivery pump 7 in such a quantity as to give a coal concn. of 65-80wt%. During the passage of coal through the agitating ball mill, coal is crushed and at the same time, coal is dispersed in water. The dispersant has effects of accelerating the dispersion of coal, lowering the viscosity of the slurry and forming a highly conc. coal/water slurry. The resulting highly conc. coal/water slurry is fed to a roll mill or a disc mill where large diameter particles in the slurry are crushed under pressure to thereby reduce the max. particle size to 40-500mu. In this way, a coal/water slurry having a coal content of 65-80wt% can be obtd.

Description

[Detailed Description of the Invention] [Technical Field] This invention relates to a method and apparatus for producing a highly concentrated coal-water slurry from coal, water, and a small amount of dispersant when coal is used for fluid transportation or as a liquid fuel. It is.

[Prior art]

In general, it has been known to use a highly concentrated coal-water slurry having a coal concentration of 65 to 80% by weight for fluid transportation of coal and use as a fluid fuel. In this case, it has been desired to develop a method of suppressing the viscosity of the slurry to a low enough level to allow pipe transportation, and increasing the coal concentration as much as possible while avoiding sedimentation of coal particles during storage.

In order to achieve the above objectives, the particle size distribution of coal particles in this slurry should be adjusted, its void wheel should be small, the maximum particle size should be suppressed to avoid coal particle settling, It is known that as the diameter becomes smaller, the viscosity of the slurry increases, so the particle size distribution should not be too biased towards the small particle size side.

Various ball mills are used as devices for producing such coal-water slurries. For example, in a rotary cylindrical ball mill, a cylinder rotating on a horizontal axis is filled with 60 to 50 balls of steel balls, and the strong impact and abrasion effects caused by the falling of the balls. It is used for crushing.

When such a rotating cylindrical ball mill is continuously supplied with coarsely pulverized coal to a size of, for example, 3 m or less, water and a dispersant from one end of the cylinder, the pulverization and dispersion of the coal particles progresses to form a coal-water slurry, which is then released from the other end. It will be discharged.

A vibrating ball mill is also known as a slurry manufacturing device. In this case, the movement of the balls is caused by vibration, but the grinding efficiency is higher than that of a rotating cylindrical ball mill. This vibratory ball mill can also be applied to the production of highly concentrated coal-water slurry.

Further, stirring ball mills are also known as slurry manufacturing equipment. This stirring ball mill stirs the balls with a stirrer installed inside a vertical or horizontal cylinder, and the vibrating ball mill also has a higher grinding vehicle. This stirring ball mill can also be applied to the production of highly concentrated coal-water slurry.

A common problem in producing coal-water slurries using the various ball mills described above is that insufficiently pulverized powder with large particle sizes remains in the product slurry. Such large-diameter particles settle and accumulate at the bottom of the storage tank, causing not only pipe clogging, but also clogging and seizure of combustion burner tips when used as liquid fuel.

In order to avoid the above-mentioned problems, it is easy to think of installing a sieve at the ball mill outlet to remove the coarse particles, but the sieve size required is not only fine, usually 90 to 600 μm. Highly concentrated coal that should be passed through this −
Since water slurry is a highly viscous fluid with a viscosity of 600 to 2000 cP, it is extremely difficult to use a sieve because it not only takes time to sieve, but also removes the powder on the sieve, causing VC<<clogging.

For this reason, a method is known in which a portion of the slurry is branched off at the ball mill outlet and recycled to the ball mill inlet.

Although this method can reduce coarse particles in the product slurry, it is difficult to eliminate them altogether. Another problem is that the productivity of the ball mill decreases due to recycling.

It is also known to use two ball mills connected in series. In this method, the coal is pulverized in two stages, which reduces to some extent the possibility that the charged coal particles are mixed into the product slurry without being sufficiently pulverized, but it is not a complete solution.

It is also known to install a weir plate inside the ball mill to prevent coal particles from flowing out from the inlet to the outlet of the ball mill. Similarly, although this method can reduce the incorporation of coarse particles into the product slurry, it cannot be prevented.

As described above, in the conventionally known method, the maximum particle size of coal is sufficiently suppressed and the highly stable highly concentrated coal-water slather II-f
It is difficult to learn.

[Summary of the invention]

The present invention has been made to solve the problems of the prior art in producing high-concentration coal-water slurry, and has a stable coal concentration of 65 to 80 when used as fluid transportation or liquid fuel. It is an object of the present invention to provide a method and apparatus for producing a weight percent coal-water slurry.

The present invention comprises the following method and apparatus.

1) Coal, water, and a dispersant are supplied to a ball mill, and the ball mill wet-pulverizes the coal and disperses it in water to form a slurry. The slurry is then processed into a roll mill with a roll gap adjusted to 40 to 500 μm or a desk gap. The maximum particle size of the coal in the slurry was 40 to 500 μm.
Coal with a coal concentration of 65 to 80 F% is obtained by IJ.

A method for producing high strength coal and water slurry, which is characterized by producing water slurry.

2) In a device that wet-pulverizes and mixes coal, water, and a dispersant to produce a coal-water slurry with a coal concentration of 65 to 85 kg/kg, a roll gap or desk gap of 40 to 500 μmK is installed at the ball mill and the ball mill outlet. A highly concentrated coal-water slurry production system @0 characterized by arranging adjusted roll mills or desk mills in series to produce a coal-water slurry. will be described based on an example.

FIG. 1 shows an embodiment of the method and apparatus according to the invention. In Fig. 1, coal that has been coarsely pulverized in advance to a size of 6 min or less is charged into the supply pumper 1, while a predetermined amount of water and a predetermined amount of dispersant are supplied to the water tank 2 and thoroughly mixed by the stirrer 5. put. First, the electromagnetic feeder 4 is activated, the coal is cut out, and the coal is sent to the quantitative feeder 6 via the conveyor 5. While cutting out coal at a predetermined feeding rate to the metering feeder 6,
The metering pump 7 supplies the water-dispersant mixture to the water tank 2.
Water is supplied from the coal mill, and the coal is adjusted and supplied to the stirring ball mill 8 so that the coal concentration is 65 to 80% by weight. While passing through the stirring ball mill 8, the coal is crushed and simultaneously dispersed into water. The dispersant facilitates this dispersion and lowers the slurry viscosity, allowing the water concentration in the slurry to be reduced, thus producing a highly concentrated coal-water slurry. The highly concentrated coal-water slurry produced in the stirring ball mill 8 is then sent to a roll mill 9, where the large-diameter particles in the slurry are compressed and pulverized to reduce the top size, and then transferred to the slurry tank 1.
Send to 0. Here, if the slurry is allowed to stand still, a thin layer may be formed on the top, and if the slurry is allowed to stand still, the viscosity increases and transportation becomes difficult, so the agitator 11 is operated as necessary.

In addition to the combination of the stirring ball mill 8 and roll mill 9 as seen in this embodiment, for example, a rotating cylindrical ball mill and a disc mill may be used. Various types of disc mills are used. Slurry is passed between reeds, for example, a fixed disc and a rotating disc, and coal particles with a particle size larger than the gap between the discs are preferentially crushed into powder by the abrasion action received from both discs. Ru. Also pre
In a colloid mill, a slurry passing section is constituted by a rotor and fixed parts adjacent thereto, and it is considered to be a type of disk mill. There are also disc mills that consist of two counter-rotating discs. In any disc mill, the maximum particle size of coal in the slurry can be adjusted by adjusting the disc gap.

The apparatus according to the present invention is a combination of a ball mill such as a rotary ball mill, a vibratory ball mill, or an agitated ball mill, and a roll mill or a disc mill. In the case of a roll mill, changing the rotation speed of the two rolls spreads the slurry on the faster rolls and improves dispersion, so this function may be provided.

Next, the effects obtained by the device according to the present invention will be explained.

Examples are shown in Table 1 along with comparative examples.

Comparative Example 1 and Example 1 in Table 1 have a coal concentration of 67.0 weight 1i.
% slurry production, and in Comparative Example 1, the slurry was sent directly from the stirring ball mill 8 to the slurry tank 10 without passing through the roll mill 9, along the broken line in FIG. In Example 1, the roll gap of the roll mill 9 is 0.3 mm (600 μm), and the material is passed from the stirring ball mill 8 to the roll mill 9 to the slurry tank 10 in this order.

In Example 1, the maximum particle size of coal in the slurry was approximately 0.3
rgrs (300μm), and as a result 14
A comparison of the slurry left standing for a day revealed that the slurry of Example 1 had better stability than the slurry of Comparative Example 1, with almost no coarse grain sedimentation observed at the bottom of the standing container.

Comparative Example 2 and Example 2 are cases of producing slurry with a coal concentration of 75.0% by weight. In Example 2 in which the slurry was passed through the roll mill 9, the roll gap of the roll mill was Oyl nrm.
(, 100 μm). This result - ○, 3
tn 100 weight i% and the size of the bulge is 0.1rIm
(100 μm). Therefore, it was found that the slurry according to Example 2 was extremely stable compared to Comparative Example 2 which was not passed through a roll mill.

In general, the higher the coal concentration, the better the stability of the slurry, and the effect of the present invention can be fully exhibited at a coal concentration of 65 weight percent or more, but it is difficult to form a slurry with a coal concentration of 80 weight percent or more. The invention is not applicable. Therefore, the present invention is effective in the coal concentration range of 65 to 80%.

If the particle size of the coal in the slurry is too finely ground, the viscosity of the slurry tends to increase extremely, making it impossible to maintain the slurry state. Therefore, it is also problematic to extremely reduce the top size by using a roll mill or a desk mill, and the lower limit of the gap between the rolls of a roll mill or the desk of a desk mill is 40 μm.

On the other hand, to keep the slurry stable, increase the top size to 500.
It needs to be less than μm. Otherwise, as already mentioned, settling of coarse particles will become impossible to ignore due to prolonged standing. Therefore, the present invention works effectively when the gap between the rolls of a roll mill or the desk of a desk mill is set to 40 to
The maximum particle size of coal in the slurry is 40 ~ 500 μm.
This is the case where the thickness is suppressed to 500 μm.

[Effects of the present invention]

As is clear from the above examples, the present invention supplies coal, water and a dispersant to a ball mill, wet-pulverizes the coal and disperses it in water to form a slurry, and then feeds the coal into a roll mill or desk mill with adjusted roll or desk gaps. By controlling the maximum particle size of the coal in the slurry by adjusting the pulverization, we have developed a method and apparatus for producing a highly concentrated coal-water slurry that is stable with little particle sedimentation even after long-term storage. This is a tremendous invention that contributes to fluid transportation and the use of coal-water slurry as a liquid fuel.

[Brief explanation of drawings]

FIG. 1 is a flowchart according to an embodiment of the invention. 1: Coal supply hopper 2: Water supply tank 6: Stirrer 4:
Electromagnetic feeder 6: Quantitative feeder 7: Quantitative pump 8: Stirring ball mill 9 Two roll mill 10 Nis slurry tank. Agent Patent Attorney Sanro Kimura

Claims (2)

[Claims] (1) Coal, water, and a dispersant are supplied to a ball mill, and the ball mill wet-pulverizes the coal and disperses it in water to form a slurry. The slurry is then processed into a roll mill or desk with a roll gap adjusted to 40 to 500 μm. The slurry was passed through a desk mill with a gap adjusted to 40 to 500 μm, and the maximum particle size of the coal in the slurry was 40 to 500 μm.
Coal with a coal concentration of 65 to 80% by weight by suppressing the water slurry - High concentration coal characterized by producing water slurry -
Water slurry production method. (2) In a device that wet-pulverizes and mixes coal, water, and a dispersant to produce a coal-water slurry with a coal concentration of 65 to 85% by weight, the roll gap or desk gap between the ball mill and the ball mill outlet is adjusted to 60 to 500 μm. Roll mills or desk mills arranged in series! A high-concentration coal-water slurry manufacturing apparatus also features a coal-cable slurry 11-fuyukatamatato L.