JPH074551B2 - Coal-water slurry production equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coal-water slurry production apparatus, and more particularly to an apparatus for producing a coal-water slurry having a high coal concentration and good fluidity with a small amount of power. Is.

(Prior art) In recent years, in order to improve the handling property of coal, which is a solid fuel, technological development of a method for making a fluid fuel that is easy to handle by dispersing coal particles in water and making a slurry has been actively carried out. Has been. In order to produce a stable coal-water slurry with a high concentration and low viscosity that can be directly spray-burned as a boiler fuel, the packing density is increased by adjusting the coal particles that make up the slurry to a wide particle size distribution. It is important to measure the viscosity and to reduce the viscosity by stably dispersing the coal particles in water by using an appropriate additive. In order to produce such a coal-water slurry, it is common to wet pulverize coal using a continuous ball mill and add a surfactant (see, for example, Japanese Patent Application No. 57-191767). . However, when producing coal-water slurry using a normal ball mill, it is necessary to grind at a high coal concentration (usually 60 wt% or more) in order to adjust to a wide particle size distribution that increases the packing density. In such a state, there is a problem in that the movement of the balls is suppressed because the viscosity in the mill becomes high, and the pulverization efficiency is lowered (the pulverization power is increased).

As a method for solving such a problem, the present inventors have proposed a method for producing a high-concentration coal-water slurry by wet pulverizing coal using a wet ring roller mill (Japanese Patent Application No. 59-203761). issue). An example of the mill structure is shown in FIG. 5, in which coal A, water B and surfactant C supplied from the coal feeding pipe 101 fall on the crushing table 102, and the coal feeding pipe 101
The coal adhering to the inner surface is scraped off by the cleaning scraper 103, then drops onto the crushing table 2, moves to the crushing roller arrangement portion by centrifugal force, and is compressed and abraded between the roller 104 and the lower ring 105. Be crushed. Ground ring 10
From the space between the 5 and the crusher main body 106, it flows down to the slurry weir 107 under the crushing table 102, and the discharge port 109 while being mixed by the mixing paddle 108 installed at the bottom of the rotating crushing table 102.
Emitted from.

(Problems to be Solved by the Invention) However, in the device shown in FIG.
It only passes once between 4 and the lower ring 105,
In order for the coal to be pulverized to a predetermined grain size, it depends on the type of coal and the pulverization conditions, but it is necessary to make the roller 104 and the lower ring 1 several times more
You have to pass between 05. Therefore, the outlet
It is necessary to return a part of the slurry discharged from 109 to the feed grinder 101 again. FIG. 6 shows a flow of the apparatus when the slurry is circulated to adjust the particle size. The coal A stored in the bunker 110 is supplied into the wet ring roller mill through the coal feeding pipe 101 by the feeder 111, and the water B and the surfactant C are supplied.
Is also added into the mill via line 112. The crushed slurry is sent from the outlet 109 to the distributor 114 by the pump 113, distributed in a predetermined ratio, a part is returned to the mill, and the rest is sent to the coarse particle separator 115 by the pump 120, The final product slurry D is stored in the tank 116.

However, the apparatus shown in FIG. 6 requires the pump 113 and the distributor 114 to circulate the slurry, which is not economical. Furthermore, when the mill is started up, a slurry having a coarse particle size and poor fluidity comes out from the discharge port 109, which easily leads to troubles on the apparatus and causes a poor slurry which cannot be used as a product.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to adjust the particle size of coal in the slurry without circulating the slurry or to reduce the number of circulations, and to produce a slurry with poor properties even at the start of the mill. Not to provide a coal-water slurry manufacturing device.

(Means for Solving the Problems) In summary, the present invention is to form an external circulation flow path for circulating the crushed coal discharged from the mill outlet to the mill inlet through the coarse grain separator in the wet ring roller mill. ,
A scraping plate for returning a part or all of the slurry to the roller part to form an internal circulation flow path is installed outside the crushing roller, and the particle size of coal is controlled by adjusting the ratio of returning to the roller part. It was done like this.

That is, the present invention provides a wet type vertical ring roller mill having a crushing ring, a roller sandwiched by the crushing ring, a means for supplying coal between the crushing ring and the roller, and a discharging means for crushed coal. An external circulation flow path is formed to circulate the crushed coal discharged from the means to the mill inlet through the coarse particle separator, and at least a part of the coal crushed by the crushing ring and the roller is the crushing ring and the roller. It is characterized in that a scraping plate is provided on the outer peripheral portions of the roller and the crushing ring so as to form an internal circulation flow path to be pushed back between them.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples. FIG. 1 shows an example of an apparatus suitable for carrying out the present invention. In FIG. 1, the coal A in the bunker 1 is the feeder 2
Is supplied to the inside of the mill 3 from the coal feeding pipe 4 of the wet ring roller mill 3, and the water B and the surfactant C are added through the pipe 5. The coal crushed to a predetermined particle size is discharged as a slurry from the discharge port 6, sent to the coarse particle separator 8 by the pump 7, and then stored in the tank 9 as the final product D. Although the distributor (114 in FIG. 6) is not installed in FIG. 1, it may be installed if necessary.

FIG. 2 shows a typical structure of the wet vertical ring roller mill 3 (wet ball race mill) used in the above-mentioned embodiment. Coal A, water B and surfactant C are coal feeding pipes 4
Although it falls on the crushing table 10 through the coal, the coal adhering to the inner surface of the coal feeding pipe 4 is scraped off by the cleaning scraping rod 11 which rotates together with the crushing table 10 and reaches the crushing table 10.
The mixture of coal A, water B and surfactant C reaching the crushing table 10 is moved to the crushing roller arrangement portion by the centrifugal force generated by the crushing table 10, and the roller 12 and the lower ring 13 are
Is compressed and ground between. The roller 12 is arranged between an upper ring 15 that is pressed by a pressure device 14 and a lower ring 13 that is installed at the end of the crushing table 10 that is rotated by a drive device 16. Part or all of the crushed coal is returned to the crushing roller arrangement portion by the scraping plate 17 fixed to the upper ring 15 or the mill body 3 and further crushed. The end of the crushing table 10 is a weir (referred to as an upper weir 18), and the slurry accumulates up to the upper weir 18, but when it exceeds this, the upper weir 18 overflows and the weir below the crushing table 10 (lower weir 19). Crushing table that flows down and rotates
The mixture is discharged from the discharge port 6 while being mixed by the mixing paddle 20 installed at the bottom of 10.

FIG. 3 shows the arrangement of the roller 12 and the scraping plate 17 as seen from the top of the apparatus having the structure shown in FIG. In FIG. 3, the angle θ between the center of the mill and the scraping plate 17 determines the rate of return of the slurry to the crushing section. In Fig. 3, when the lower ring rotates to the right when viewed from above, if θ is 90 degrees or more, it does not promote the return of the slurry, and conversely θ
If the value is too small, the amount of returned slurry will decrease. Generally 30
About 80 degrees is preferable. This angle θ can be fixed at a substantially constant value if the specifications of coal type and slurry and manufacturing conditions are determined, but it is also possible to measure the particle size of the product online and perform feedback control of θ.

Table 1 shows a comparison of power consumption units in the conventional method shown in FIGS. 5 and 6 and the method of the present invention shown in FIGS. 1 and 2.

The conventional method shown in FIGS. 5 and 6 is based on A charcoal (HGI = 5
Regarding 0), the case where a slurry having the same properties is produced by using the same surfactant is shown. From this table, it is understood that in the method of the present invention, not only the pump power for sending the slurry to the distributor but also the grinding power is reduced. This is considered to be because the distribution of the slurry between the roller and the lower ring was nonuniform in the conventional method, but the distribution of the slurry was uniform in the method of the present invention, and unnecessary movement of the roller was eliminated.

Although the apparatus having the upper weir 18 is taken as an example in the apparatus of FIG. 2, the method of the present invention is effective even when the upper weir 18 is not provided.

Further, although the upper weir 18 shown in the apparatus of FIG. 2 has a simple wall shape, by incorporating a coarse particle separator such as a screen here, the coarse particle separator 8 outside the mill in FIG. 1 becomes unnecessary. be able to.

FIG. 4 shows the structure in which the upper weir 18 is the screen 21. By providing the brush 22, coarse particles on the screen surface can be scraped off and clogging of the screen can be prevented. It is also possible to use only part of the upper weir as a screen.

Hereinafter, the effects of the method of the present invention will be described in more detail with reference to specific examples.

Example 1 For coal B (HGI = 36), a comparison of power between a case where a good slurry was produced by the conventional method shown in FIGS. 5 and 6 and a case where a slurry was produced by the method of the present invention shown in FIGS. 1 and 2 was compared. I did. However, the surfactant used and the properties of the final slurry (coal concentration, particle size and viscosity) were the same.

In the case of the conventional method, the mill power was 48 kwh / t and the auxiliary machine power was 12 kwh / t, but in the method of the present invention it was 42 kwh / t and 4 kwh / t, respectively, and it was possible to reduce the power by about 23% as a whole. .

Example 2 The same comparison test as in Example 1 was carried out on C charcoal (HGI = 80). The conventional method had a mill power of 27 kwh / t and an auxiliary machine power of 10 kwh / t. 22k each
It became wh / t and 3kwh / t, and the total power could be reduced by about 32%.

As described above, according to the present invention, the power consumption can be reduced by 20 to 35% as compared with the conventional method regardless of the properties of coal.

(Effect of the invention) According to the present invention, while forming an external circulation flow path that circulates from a mill outlet to a mill inlet through a coarse grain separator, at least a part of coal pulverized by a pulverizing ring and a roller is pulverized. By providing a scraping plate on the outer peripheral side of the roller and the crushing ring so as to form an internal circulation flow path for pushing back between the ring and the roller, the ring-roller mill circulates the coal-water slurry through the external circulation flow path. In addition to reducing the number of times of operation, it is possible to reduce power, and in some cases, the conventional distributor is not required, and the device can be simplified.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of a coal-water slurry manufacturing apparatus of the present invention, FIG. 2 is a sectional view of a vertical ring roller mill used in the present invention, and FIG. 3 is a schematic plan view of an important part thereof. FIG. 4 is a partial detailed view of FIG. 2, FIG. 5 is a sectional view of a conventional vertical ring roller mill, and FIG. 6 is an explanatory view of a conventional coal-water slurry manufacturing apparatus having a distributor. 1 ... Bunker, 2 ... Feeder, 3 ... Wet ring roller mill, 4 ... Coal feeding pipe, 5 ... Pipe line, 6 ... Discharge port, 7
…… Pump, 8 …… Coarse grain separator, 9 …… Tank, 10 ……
Grinding table, 11 …… Shaking bar, 12 …… Ball or roller, 13 …… Lower ring, 14 …… Pressurizing device, 15 …… Upper ring, 16 …… Drive device, 17 …… Scraping plate, 18 …… Upper weir, 19 …… Lower weir, 20 …… Mixing paddle, A …… Coal, B ……
Water, C ... surfactant, D ... slurry.

Claims (4)

[Claims] 1. A wet vertical ring roller mill having a crushing ring, rollers sandwiched by the crushing ring, means for supplying coal between the crushing ring and the rollers, and means for discharging crushed coal. While forming an external circulation flow path to circulate the crushed coal discharged from the mill through the coarse particle separator, at least a part of the coal crushed by the crushing ring and the roller and the crushing ring and the roller. A coal-water slurry manufacturing apparatus, characterized in that a scraping plate is provided on the outer peripheral portions of the roller and the crushing ring so as to form an internal circulation flow path to be pushed back between them. 2. The installation angle of the scraping plate is adjustable in order to control the particle size of the coal by changing the internal circulation rate of the coal to the roller portion according to claim 1. Coal-water slurry production equipment. 3. A coal-water slurry manufacturing apparatus according to claim 1 or 2, wherein a weir is provided outside the scraping plate to prevent a short path of coal. 4. A coarse particle separating device such as a screen is provided outside the scraping plate in order to prevent coarse particles from being discharged to the outside of the mill according to claim 1 or 2. A coal-water slurry manufacturing device characterized by the above.