JPH0651126B2 - Coal-water slurry manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a coal-water slurry, and more particularly to a method for producing a coal-water slurry which is suitable for reducing the pulverization power consumption.

(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. The challenge for producing stable coal-water slurry with high concentration and low viscosity that can be directly spray-burned as boiler fuel is to increase the packing density by adjusting the coal particles constituting the slurry to a wide particle size distribution. It is intended to reduce the viscosity by densification and by stably dispersing coal particles in water by using an appropriate additive. In the case of producing such a coal-water slurry, it is common to wet pulverize coal using a normal continuous ball mill and add a surfactant. (For example, Japanese Patent Application No. 57-
191767). However, in the case of producing a coal-water slurry using an ordinary ball mill, it is necessary to pulverize 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, since the viscosity in the mill becomes high, there is a problem that the movement of the balls is suppressed 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). ). An example of the mill structure is shown in FIG. 5, but coal A, water B, and surfactant C supplied from the coal feeding pipe 101 fall on the crushing table 102, and coal adhering to the inner surface of the coal feeding pipe 101 is cleaned. Scraping stick 1
After being scraped off by 03, it falls on the crushing table 102, moves to the crushing ball arrangement portion by centrifugal force, and is compressed and ground between the balls 104 and the lower ring 105. The crushed coal flows down from the space between the lower ring 105 and the crusher main body 106 to the slurry weir 107 below the crushing table 102, and is mixed by the mixing paddle 108 installed at the bottom of the rotating crushing table 102, while discharging the discharge port. It is discharged from 109. In the apparatus shown in FIG. 5, the coal passes between the ball 104 and the lower ring 105 only once, and in order for the coal to be crushed to a predetermined particle size,
Although it depends on the type of charcoal and the grinding conditions, it is necessary to pass the balls 104 and the lower ring 105 several times or more. Therefore, a part of the slurry discharged from the discharge port 109 is recirculated to the supply pipe 101.

The ratio of the amount of coal and water supplied in the apparatus shown in Fig. 5 is determined from the final viscosity of the slurry. That is, generally, an appropriate viscosity for pumping or spray burning coal-water slurry is about 1000 cp or less, but considering the stability during storage, it is a problem that the viscosity is too low, and it becomes about 1000 cp. It is preferable to determine the ratio of the amount of coal and the amount of water supplied.

However, even if such an apparatus is used, the power unit required for producing coal-water slurry is larger than that of pulverized coal burning,
In order to reduce the production cost of coal-water slurry, it is desired to develop a production method that requires a smaller pulverization power unit.

(Problems to be Solved by the Invention) It is an object of the present invention to provide a method for producing a coal-water slurry which eliminates the above-mentioned drawbacks of the prior art and can reduce the crushing power consumption.

(Means for Solving Problems) In short, the present invention detects the coal concentration during crushing, and determines the constant moisture content (%) of the crushed coal so that the crushing power consumption rate becomes the minimum coal concentration. 3 times and the total of coal concentration (ratio of coal weight to total weight of coal, water and surfactant) (%) at the time of crushing becomes 75 to 85 (%),
At least one of the amounts of coal, water and surfactant supplied to the mill is adjusted.

Factors that affect the pulverization power consumption rate when wet pulverizing coal using a wet ring roller mill include the pulverizability (HGI) of coal, the coal concentration during pulverization, and the amount of surfactant (including pulverization aid). Etc. are possible. We have
As a result of various studies on each factor, it was found that by adjusting the coal concentration during crushing to an appropriate range, the crushing power consumption rate can be significantly reduced. However, since the appropriate concentration differs depending on the coal, it is necessary to readjust the crushing conditions when the coal changes. Therefore, as a result of various studies on the difference in the appropriate crushing concentration depending on the coal, a method of correcting with the constant moisture content of the coal I found it. That is, a total of three times the constant moisture content (%) of coal and the coal concentration (%) at the time of crushing (hereinafter, referred to as correction concentration) is within a predetermined range (75 to 8).
It was found that by adjusting the coal concentration at the time of crushing so as to be 5%), the crushing power can always be minimized regardless of the type of coal.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings. First
The drawing shows an example of an apparatus suitable for an embodiment of the present invention. In FIG. 1, the coal A in the bunker 1 is the feeder 2
Is supplied from the coal feed pipe 4 of the wet ring roller mill 3 into the mill 3. The surfactant and water stored in the tanks 5 and 6, respectively, are supplied into the wet ring roller mill 3 from the coal feeding pipe 4 through the pipes 9 and 10 by the pumps 7 and 8, respectively. The slurry of coal and water crushed by the wet ring roller mill 3 is discharged from the mill discharge port 11 by the pump 12 and sent to the distributor 13. At this time, the coal concentration in the slurry discharged from the mill discharge port 11 is continuously or discontinuously measured by the concentration measuring device 14, and the resulting coal concentration (%) and the moisture content (%) of the corresponding coal are measured. ) Three times the total is 75 to 85
(Preferably 78 to 82) (%), coal,
Any one of the supply amounts of surfactant and water is controlled. In this case, it is preferable to adjust the surfactant supply amount when the coal supply amount changes.

A part of the slurry distributed by the distributor 13 is a pipe line 15.
To the coarse grain separator 17 by the pump 16 and the coarse particles are returned to the mill via the line 18. The slurry from which coarse particles have been removed has a viscosity adjusting device 19
Water is added or water is removed to adjust the viscosity to an appropriate range (about 500 to 2000 cp), and the final product slurry D is sent to a combustion device or the like.

The structure of the wet ring roller mill 3 shown in FIG. 1 is the same as that of the prior art shown in FIG.

In FIG. 1, the concentration of coal in the slurry is measured for the slurry at the mill outlet, but it may be anywhere as long as the concentration of coal at the time of crushing can be detected. A method of detecting the coal concentration by measuring the activator supply amount and the water supply amount is also effective. Further, as the coal concentration measuring device 14,
Any device that can directly or indirectly measure the coal concentration may be used, and examples thereof include a densitometer and a moisture meter. Further, the viscosity adjusting device 19 is provided on the downstream side of the coarse particle separating device 17, but may be installed on the upstream side thereof.

Fig. 2 shows the relationship between the crushing power consumption and the coal concentration during crushing when A coal (constant humidity water 5.1%) was wet crushed with the device shown in Fig. 1 to a passing amount of 200 mesh of 70%. But,
It can be seen that the crushing power consumption rate is remarkably reduced when the coal concentration is 60 to 70%. However, at the time of pulverization, a formalin condensate of sodium naphthalenesulfonate was added as a surfactant in an amount of 0.5 wt% with respect to coal.

Similarly, B charcoal (constant moisture content 1.8%) and C charcoal (constant 0.
Fig. 3 shows the results of determining the relationship between the crushing power consumption rate and the coal concentration during crushing for 9%). Similar to A coal, B coal and C coal also have a certain coal concentration range (68 B
78%, and 73 to 83% in the case of C charcoal). As described above, by setting the coal concentration at the time of crushing for each coal to an appropriate range, it is possible to significantly reduce the crushing power consumption rate. However, since the appropriate concentration differs depending on the coal, it is necessary to readjust the grinding conditions when the coal changes. As a result of various studies on the difference in the appropriate crushing concentration depending on the coal, the inventors have found that the appropriate concentration can always be obtained by correcting the constant moisture content of the coal. That is, the coal concentration during crushing should be adjusted so that the total of the moisture content (%) of the constant humidity of the coal (%) and the coal concentration (%) during crushing (hereinafter referred to as the correction concentration) becomes an appropriate value. Good. FIG. 4 shows the pulverization power consumption rate for A, B, and C coals, where the horizontal axis is the corrected concentration obtained by adding three times the constant humidity water. The corrected concentration is 75 to 85 for all coals.
(Preferably 78 to 82) (%), the crushing power consumption rate is the minimum. Table 1 shows the results of obtaining the corrected concentration when the basic unit of pulverization power was minimized by conducting the same examination for other x number coal types. For all coals, the corrected concentration is 75 to 85 (%). Has become.

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

Example 1 For A charcoal, a viscosity of 1000 c was obtained using an apparatus based on the method of the present invention shown in FIG. 1 and a conventional apparatus shown in FIG.
A slurry having a p, 200 mesh passing amount of 70% was produced.
However, 0.5% of a formalin condensate of sodium naphthalenesulfonate was added as a surfactant to coal. The crushing power consumption unit at this time is 40 (kw
h / t-coal), whereas in the method of the present invention it is 20 (k
wh / t-coal), which was 50% of the conventional value. Further, the coal concentration in the slurry at this time (at a viscosity of 1000 cp) was 60% in the conventional technique, but according to the method of the present invention, a slurry having a high concentration of 64% and 4% could be produced.

Example 2 A slurry of B charcoal was produced under the same conditions as in Example 1. As a result, the crushing power consumption rate was 42 (kw) as compared with the prior art.
h / t-coal) to 22 (kwh / t-coal), and the concentration at a viscosity of 1000 cp increased from 68% to 73%.

Example 3 A slurry was produced for C charcoal under the same conditions as in Example 1. As a result, the crushing power consumption rate was 41 (kw) as compared with the prior art.
h / t-coal) to 20 (kwh / t-coal), and the concentration at a viscosity of 1000 cp increased from 73% to 76%.

As described above, according to the method of the present invention, the pulverization power consumption rate is about 5
It is also reduced by 0%, and the coal concentration at the same viscosity is, for example, 2 to
It can be reduced by 5%.

(Effect of the Invention) According to the method of the present invention, the pulverization power of the mill during coal-water slurry production is significantly reduced, and a slurry having a high coal concentration and the same viscosity can be produced.

[Brief description of drawings]

FIG. 1 is a diagram showing a flow of an apparatus used in an embodiment of the present invention, FIGS. 2, 3, and 4 are diagrams showing experimental examples of the present invention, and FIG. 5 is a diagram showing a conventional technique. It is a figure which shows a device structure. 1 ... Bunker, 2 ... Feeder, 3 ... Wet ring roller mill, 4 ... Coal feeding pipe, 5,6 ... Tank, 7,8,1
2, 16 ... Pump, 9, 10, 15, 18 ... Pipe line,
11 ... Discharge port, 13 ... Distributor, 14 ... Concentration measuring device, 17 ... Coarse particle separator, 19 ... Viscosity adjusting device, A ...
... Coal, B ... Surfactant, C ... Water, D ... Slurry.

Claims (4)

[Claims] 1. A method for producing a coal-water slurry by wet pulverizing coal in the presence of water and a surfactant using a wet vertical ring roller mill having a pulverizing ring and a roller, in which the slurry during pulverization is used. Of the coal (the ratio of the weight of coal to the total weight of coal, water and a surfactant) is detected, and the total of three times the coal concentration (%) and the constant moisture content (%) of the coal is 75 to 85 ( %), At least one of coal, water, and a surfactant to be supplied to the mill is controlled so that the amount of the coal-water slurry is increased. 2. The method according to claim 1, wherein at least one of the water content (%) in the slurry after crushing, the viscosity of the slurry and the density of the slurry is used to detect the coal concentration in the slurry during crushing. A method for producing a coal-water slurry, characterized in that 3. The coal supply amount at the inlet of the mill and the water content thereof, and the water and surfactant supply amounts according to claim 1 or 2 are measured, and from the results, the coal in the slurry at the time of crushing is measured. A method for producing a coal-water slurry, which comprises detecting the concentration. 4. The viscosity of the slurry as set forth in any one of claims 1 to 3, wherein the viscosity of the slurry is adjusted by adding water to or removing water from the slurry after crushing. Method for producing coal-water slurry.