JPH0698319B2 - Coal / water slurry production equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for producing a slurry of coal and water, and more particularly to a mill structure suitable for preventing backflow of slurry and balls in a mill.

(Prior Art) Fuels used in combustion devices such as boilers include fluid fuels such as heavy oil and LNG, and solid fuels such as coal. A coal / water slurry prepared by suspending coal with an additive such as a surfactant and water to form a slurry has attracted attention as a boiler fuel because it facilitates handling during transportation and storage. This coal / water slurry is generally called CWM, and when it is directly burned, the coal concentration is as high as about 60% or more, and the particle size is adjusted so that the 200Mesh passage amount is about 70-80%. Also in this case CWM must be a pumpable and stable low viscosity liquid. The conditions for producing stable CWM with high slurry concentration, low viscosity are (1) increase the packing density of particles by adjusting a wide range of viscosity distribution, and (2) add particle surface by adding a dispersant. It is to lower the viscosity by forming a water film on the surface of the particles to disperse the particles and disperse the particles. As a method for continuously producing such CWM, a method using a continuous wet ball mill is generally used.

Figure 3 shows a system diagram of the CWM manufacturing facility using a continuous wet ball mill. In the figure, coal A is supplied from bunker 1 to coal feeder 2
And the water B and the additive liquid C are supplied from the tanks 4 and 5 into the mill 3 from the pumps 6 and 7, respectively. Manufactured in mill 3
CWM is discharged to the slurry adjusting tank 8 and supplied to the coarse particle separator 10 by the pump 9. The coarse particles separated by the coarse particle separator 10 are returned to the mill 3 again and re-ground. The CWM manufactured in this way is used as fuel for electric power, for example.

However, due to the recent power situation, DSS (D
aily stop start) is required, and of course the DSS method is also desired for CWM fired boilers. Therefore, frequent stop and start of the high-concentration wet tube mill that processes and supplies fuel is unavoidable.

However, the conventional wet tube mill has the following drawbacks. FIG. 4 shows the structure of the inlet of a conventional wet tube mill. The tube mill 23 is filled with balls 24, and the coal feeder 21 is installed at one end of the center of rotation of the tube mill 23. Coal feeder 21 is fixed,
The tube mill 23 rotates at a constant speed. Tube mill 23
Inside, a predetermined amount of coal and water and an additive are supplied from a coal feeder 21 and water and an additive supply pipe, and crushed by balls 24 to produce CWM. At this time, a backflow prevention plate 22 for preventing backflow of CWM and balls is provided at the insertion portion of the coal feeder 21 into the tube mill 23. The backflow prevention plate 22 is fixed to the coal feeder 21, but may be damaged by the vigorous movement of the balls 24 in the tube mill 23. That is, the ball filling rate (volume percentage) in the tube mill is 30-40%, but as shown in Fig. 5, the ball space is filled with CWM, and as the mill rotates, the balls also reach the center of the mill. It collides and damages the backflow prevention plate 22 and hinders the rotation of the tube mill or stops the mill.
Backflow of CWM occurs.

FIG. 6 shows a tube mill 23 for solving the above problems.
Fix the backflow prevention blade 26 at the inlet, and with the rotation of the mill,
It is designed to prevent backflow of the balls 24 and CWM25 in the mill. However, as described above, since frequent start and stop of the tube mill are required, even in this method, a large amount of CWM flows out especially when the mill is stopped. This amount can reach tens of percent of the tube mill volume.

By the way, if the volume in the mill is V, the ball filling rate is J, the slurry volume in the mill is Fccwm, and the ball porosity is ε, the hold-up amount U of CWM can be expressed by the following equation.

Fig. 7 shows the relationship between the hold-up amount in the mill and the coal concentration during CWM production. As the coal concentration increases,
Hold-up amount U rises, U = 2 at 70% coal concentration
Also reaches. Fig. 7 shows the characteristics of A charcoal, but CW
The operating range of M is, for example, the range of coal concentration of 69 to 71%.
Hold-up U = 1.0 is nearly achieved with conventional low-density grinding (about 50%). In other words, since the hold-up amount is small in conventional low-concentration grinding, CWM in the mill does not flow out of the system when the mill is stopped, but in the case of high-concentration coal / water slurry (CWM), the hold-up amount is increased. Since the amount is large, a large amount of CWM will flow out of the system when the mill is stopped.

Therefore, even if the backflow prevention blade 26 as shown in FIG. 6 is adopted, not only does the CWM become dry and adhere to the backflow prevention blade 26 and the function of preventing the backflow of CWM is not fulfilled, but a large amount of CWM flows out from the vicinity of the mill inlet. And it will have to be treated as waste slurry. Furthermore, there is a problem that small balls worn in the tube mill flow out of the system at the same time as CWM.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to prevent backflow of slurry and balls from within the mill by frequent activation,
It is to provide a coal / water slurry manufacturing apparatus that can be prevented despite the suspension.

(Means for Solving Problems) In short, the present invention has a structure in which a blade for slurry and ball extrusion independent of the mill and the coal feeder is provided at the inlet of the wet tube mill, and the blade is continuously driven. is there. That is, the present invention is a coal / water slurry manufacturing apparatus comprising a continuous wet tube mill in which a coal feeder is inserted into an inlet of a rotary driven mill, and the outer periphery of an insertion portion of the coal feeder of the mill inlet is slid. It is characterized in that it has a rotating shaft movably provided, a spiral backflow preventing blade fixed to the rotating shaft, and a driving means for the rotating shaft.

(Example) FIG. 1 is a cross-sectional view of a coal feeder mounting portion of a tube ball mill showing an example of the present invention. This device comprises a backflow prevention vane shaft 32 slidably provided on the outer periphery of the coal feeder 21 at the inlet of the tube mill 23, a spiral backflow prevention vane 31 attached to the shaft, and the shaft. It is composed of two gears 33, 34 and a driving device 35.

The backflow prevention blade 31 is used for the coal feeder 21 and the tube mill.
It has a structure that can be driven independently of 23, and its rotation direction is always the direction to push the substance (CWM etc.) into the mill.

This backflow prevention vane starts driving at the same time as before the mill starts or before the mill starts, continuously drives during the mill operation, and when the mill stops, until the slurry outflow from the mill stops,
It is preferably driven for 5 to 30 minutes. CW that flows backward from the mill inlet side by driving the backflow prevention blade even after the mill is stopped
M and small balls worn can be prevented.

FIG. 2 shows another embodiment of the present invention, which is basically the same as the structure of FIG. 1 except that the backflow preventing vanes 31 are used to supply the balls into the mill. Different.
That is, the ball replenishing port 36 and the box 38 were installed at the inlet of the tube mill 23, and the replenishing ball 37 was thrown in from the ball replenishing port 36 so that the ball could be supplied into the mill by the rotation of the backflow preventing blade 31. The ball supply port 36 and the box 38 have a structure in which the backflow preventing blade 31 is extended to the inside so that the ball can be smoothly fed into the mill. Box 38 also
The tube mill 23 and the backflow prevention blade 31 are fixed independently.

The wear of balls in the mill is an important issue for practical machines, and the wear amount is said to reach 100 to 400 g per ton of coal. If the backflow of CWM can be prevented and the ball can be replenished at the same time as in this embodiment, the advantageous effect can be obtained.

(Effects of the Invention) According to the present invention, troubles due to frequent start and stop of the mill during CWM production can be eliminated, and waste slurry can be reduced, so maintenance in CWM production can be simplified and CWM production cost can be reduced. Is possible.

[Brief description of drawings]

FIG. 1 is a sectional view of the vicinity of a coal feeder of a tube mill showing an embodiment of the present invention, FIG. 2 is a similar sectional view showing another embodiment of the present invention, and FIG. 3 is a CWM manufacturing facility. FIG. 4 is an explanatory view showing a conventional mill structure, FIG. 5 is an explanatory view showing behavior of balls in the mill, and FIG.
FIG. 7 is an explanatory diagram showing the structure of a conventional mill, and FIG. 7 is an explanatory diagram showing the relationship between the holdup amount and the coal concentration in the mill. 21 …… Coal feeder, 23 …… Tube mill, 24 …… Ball, 25 …… CWM, 31 …… Backflow prevention vane, 32 …… Backflow prevention vane shaft, 33 …… Gear (1), 34 …… Gear ( 2), 35 ……
Drive device, 36 ... Ball supply port, 37 ... Replenishment ball, 38
……box.

Claims (2)

[Claims] 1. A coal comprising a continuous wet tube mill in which a coal feeder is inserted at the inlet of a rotary driven mill.
In the water slurry manufacturing apparatus, a rotary shaft slidably provided on the outer periphery of the insertion portion of the coal feeder at the mill inlet, a spiral backflow prevention blade fixed to the rotary shaft, and the rotary shaft of the rotary shaft. A coal / water slurry production apparatus comprising: a driving means. 2. The device according to claim 1, further comprising means for replenishing balls in the mill through a rotary shaft provided on the outer periphery of the coal feeder and a spiral backflow prevention blade. Coal / water slurry manufacturing equipment.