JPS6072995A - Production of highly concentrated coal/water slurry - Google Patents

Abstract

PURPOSE:To form a slurry having a high concn. and a low viscosity with a small quantity of an additive, by feeding the additive in separate stages to a tubular mill in the production of the titled slurry using a wet-process tubular mill. CONSTITUTION:Coal is fed from a hopper 1 through a constant feeder 2 to a wet-process tubular mill 5. At the same time, water and an additive are fed from a liquid feed tank 3 to the mill 5. The resulting coal/water slurry is transferred through a discharge pipe 6 to a slurry adjusting tank. In the above process, a soln. contg. the additive through a plurality of liquid supply nozzles provided along the crushing direction (moving direction) of coal within the tubular mill is fed to the mill 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly concentrated coal-water slurry.
The present invention relates to a method for producing stable slurry using a 'ic multi-stage liquid supply method.

Recently, coal has been increasingly used as a substitute for oil, mainly in thermal power plants. However, coal, which is a fixed fuel, is difficult to handle, and transportation costs are lower than the price of coal, which has a large impact. Therefore, efforts are being made to actively develop technologies to turn coal into a slurry so that it can be handled as a fluid.

One of them is c, which is a mixture of heavy oil and coal.

P/i (Coal and Oil Mixture
). However, in the case of COM, the weight ratio of heavy oil to coal is approximately 1=1, so it cannot be said to be a completely blood-free oil fuel, and there is little advantage in terms of price. Furthermore, methacol, which is a mixture of methanol and coal, is expensive and has not yet reached the practical stage.

On the other hand, CWM (Coa) is a mixture of coal and water.
L and Water Mixture) is quite practical in terms of price and has been attracting attention recently. This c
To produce wMt, a method is generally used in which water is added to coal and wet pulverization is performed. However, there is a problem in that if the proportion of water in the CWM is high, the thermal efficiency during combustion will decrease, and if the moisture content is low, the viscosity of the CWM will increase and the pressure loss during transportation will increase. Furthermore, since CWM is composed of coal particles and water, there is a storage problem in that the coal particles settle and separate from the water over time. In order to eliminate these drawbacks, it is possible to produce CWM with high coal concentration, low viscosity, and good stability by adjusting the particle size distribution of coal particles or by adding additives. The disadvantage is that the cost is high due to the large amount of

Conventionally, in order to produce a slurry with high coal concentration, low viscosity, and good stability, it has been necessary to add additives to the supplied coal and water and to grind the coal to a particle size that maximizes the coal filling rate. It is said to be desirable. As such a method, as shown in FIG. 1, for the wet tube mill 5,
Coal and additive liquid are simultaneously supplied from the coal hopper 1 and the liquid supply tank 3 through the supply pipes 2 and 4, and the coal is pulverized at a high coal concentration (generally 60 to 80% by weight, the same applies hereinafter) (high concentration wet pulverization). However, if additives are added all at once, the excess additives will be adsorbed on the coal surface and the amount of additives consumed will increase.Also, additives are expensive, so adding large amounts will cause the chemical slurry to deteriorate. The disadvantage is that the cost is high.In the figure, 6 is a slurry discharge pipe and 7 is a slurry adjustment tank.Therefore, it is necessary to supply as little amount of additive as possible and produce a stable and highly concentrated slurry. This becomes a major issue.

An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a method for producing an inexpensive coal-water slurry with high coal concentration, low viscosity, and a small amount of additives.

The present invention provides a method for producing a highly concentrated coal-water slurry in which coal and additives are supplied into a wet tube mill and wet-pulverized, in which the additives are supplied in multiple stages in the direction of pulverization of coal in the tube mill. It is characterized by

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 2 is a conceptual diagram of a coal-water slurry manufacturing apparatus showing an embodiment of the present invention. In the figure, coal stored in a coal hopper 1 is supplied into a wet tube mill 5 from a quantitative coal supply pipe 2, and at the same time, water and additives are supplied from a liquid supply tank 3 through a liquid supply pipe 4 to the same wet tube mill 5. supplied within. The coal concentration at this time is 50 to 80% (preferably 60 to 7ou), and the liquid containing the additive is fed into the three cylinders installed in the pulverizing direction (traveling direction) of the coal in the tube mill. The liquid is divided into three parts from the liquid nozzle 8 and supplied into the wet tube mill. Coal produced in a wet tube mill
The water slurry (CWM) is sent to a slurry adjustment tank 7 through a slurry discharge pipe 6, and from there is transported to a combustor or the like by a slurry pump or the like as necessary.

When coal is pulverized in a wet tube mill, the coal particle size near the sunrise is large and the surface area of the coal is small.
Although the amount of additives attached to the surface is small, the coal particle size near the mill outlet is very fine and the surface area is large, so the amount of additives attached to the surface is also large. That is, by adjusting the amount of the additive depending on the coal particle size, that is, by performing multistage liquid supply, the amount of the added potash agent can be significantly reduced.

In addition, in the conventional method shown in Figure 1, since the additive is supplied in one stage, there is a large excess of additive near the mill entrance, and the excess additive is adsorbed on the coal surface in multiple layers. However, more additives than necessary are consumed because they penetrate into the pores of the coal. Figure 2 shows an example of three-part liquid supply, but depending on the coal properties or the size of the mill, the liquid may be divided into two or in multiple stages, or if the liquid is supplied in multiple stages, the amount of additive may be changed to a particle size. It may be increased stepwise as the surface area increases.

FIG. 3 shows a method of dispersing and supplying the additive liquid into the mill using one liquid supply nozzle 8' which can widely disperse the additive liquid. According to this method, the number of liquid supply nozzles can be reduced and the apparatus can be simplified.

FIG. 4 shows a method of supplying additives in the form of powder. The additives are supplied from the additive tank 9 into the mill 5 through the additive supply pipe 10 and sprayed from the additive nozzle 13.
Air from the Shiki 4 air supply pipe 11 is used as the air supply gas. Also, water is supplied into the mill from the water supply pipe 12. Since this method supplies additives and water separately, it is possible to maintain a constant moisture concentration within the mill.

The supply is installed from two locations on the exit side.

FIG. 6 shows an example of application of the present invention to a multi-stage wet grinding process. Coal is supplied to the first stage mill 5, and additive liquid is supplied from the tank 3 accordingly. The slurry produced here is sent to the secondary wet tube mill 14, where additives are added from the secondary liquid supply tank 17 and pulverized.

The slurry produced here is further sent to the tertiary wet tube mill 15 from the secondary product slurry discharge pipe 19, and additives are supplied from the tertiary liquid supply tank 18, and the CWM of the final product is taken out from the product slurry discharge pipe 16. be done.

FIG. 7 shows an example of application to a process in which large particles are classified from a product slurry using a classifier 20 and then circulated through a recycling pipe 21 to the mill inlet. In this case, the final product is extracted from the system through the product slurry discharge pipe 22.

Figure 8 shows 7 of 950 dragon φ x 1900 tomocho! A-type tube mill uses Miike charcoal as the raw material coal, and additives L.
- Addition in one stage (additive 0.4%) and three stages (additive concentration in each stage from the mill inlet is 0.1%, 0.2%, 0.4%) while keeping the amount of mill constant. 1%). In the figure, 30 is 1-stage addition, 31 is 3-stage addition.
The case of stage addition is shown.

From this result, it is clear that for the same slurry viscosity, the coal concentration is higher when three stages are added.

However, when producing CWM with the same coal concentration and the same viscosity, it can be seen that a smaller amount of additive P can be used if the additive is added in multiple stages.

FIG. 9 is an explanatory diagram showing still another embodiment of the present invention using a multi-chamber mill. In the figure, coal A is supplied into the mill 5 from the coal pumper 1 via the coal feed fi 52.

Water B and additive liquid C are quantitatively supplied from the respective tanks 54 and 55 to the recovery tank 65 by the respective pumps 56 and 57, and are mixed with the coarse particles separated by the coarse particle separator 60 by the stirrer 66, The coarse slurry is injected from the recovery tank 65 into the mill 5 via the recovery pipe 64.

The mill 5 is dinitrided by installing a partition plate 71 such as a screen, and each chamber is filled with balls of different diameters. In this case, the first room contains approximately 75 to 40
m1 large-diameter balls, and the second chamber is filled with small-diameter balls of about 40 to 12 tuna. The slurry that has passed through the finishing J plate 71 is efficiently pulverized by small-diameter balls in the second chamber, and the particle surfaces are efficiently wetted by the additive newly added from the liquid supply pipe 70, thereby reducing the viscosity.

The slurry discharged from the mill 5 is mixed in a tank 58 with separately supplied additives or additive particles by a stirrer to further reduce the viscosity. In this way, as the surface is generated by grinding the particles, additives or additive liquids are added little by little in multiple stages inside and outside the mill, and the additives are effectively mixed with the particles. There is no waste of the agent, and the amount used can be reduced. Next, mill 5
The CWM produced in the CWM enters the slurry tank 58, where additive liquid and water are added as necessary from the supply pipe 80 and the pipe 81, and the CWM is adjusted by the pump 59.
II grain pre-separation device 60. The coarse particle content δ■ device 60 includes
A vibration generator 72 that applies vibration or ultrasonic waves to the screen 61 is provided. The vibrations or ultrasonic waves from the vibration generator reduce the viscosity of the slurry present near the screen 61, making it easier for the slurry gas to pass through the screen 61. Further, due to the vibration, coarse particles that do not pass through the screen 61 tend to overflow the screen 61. The vibration generator 1lff22 may be provided independently, but it is also possible to use the vibration of the mill 5. It passes through the screen 61 and is transported out of the system as a product through the discharge hole 62. On the other hand, coarse particles that do not pass through the screen 61 overflow on the screen 61, enter the recovery tank 65 through the discharge hole 63, and are filled with water as described above. B and additive liquid C are mixed and passed through the coarse slurry recovery pipe 64.
It is injected into ζ mill 5.

According to the above embodiment, the water and additive liquid to the mill are first supplied to the recovery tank 5 and mixed with the coarse slurry, so that the solids concentration of the coarse slurry is reduced to about 35% or less,
Since the slurry can be made to have the viscosity of a water dish, and the slurry is circulated in the mill 5 by gravity flow through the collection pipe 64, CWM of uniform quality can be continuously produced. In addition, as described above, the additives can be supplied and adjusted from inside the mill, that is, from the supply pipe 64 at the inlet, the supply pipe 70 at the outlet, and the supply pipe 80 of the slurry tank 58, so that the additives can be adjusted in a rational manner. can be added and the amount used can be reduced.

In the embodiment described above, the coarse slurry from the recovery tank 65 is returned to the mill 5 by gravity, but a pump may be provided midway to supply the coarse slurry in a fixed amount. With this shift, the circulating coarse slurry is supplied to the mill in a fixed amount by the pump in the same way as the additive liquid, which reduces fluctuations in the grinding system and allows for more stable operation, as mentioned above. According to the present invention, by supplying the additive in multiple stages within the tube mill, the use of the additive can be reduced and the cost of CWM can be reduced.

[Brief explanation of drawings]

Figure 1 is a diagram showing the flow of a coal-water slurry production apparatus using a conventional wet mill, Figures 2 to 7, and 9.
The figures are diagrams showing the flow of similar equipment for carrying out the present invention, and Figure 8 is the experimental results (relationship between viscosity and coal concentration) for single-stage addition and multi-stage addition using a small wet mill.
FIG. ■・・・Coal dropper, 2...Coal supply pipe, 3...
Liquid supply tank, 4... Liquid supply pipe, 5... Wet tube mill, 6... Slurry v1 outlet pipe, 7... Slurry adjustment tank, 8... Supply skin nozzle. Agent Patent Attorney Takenaga Kawakita Figure 1 Figure 2 Figure 4 Figure 1 Figure 8 Ishiyone Yu A ('/,) Figure 9 M

Claims (3)

[Claims] (1) In a method for producing a highly concentrated coal-water slurry in which coal and additives are supplied into a wet tube mill and wet-pulverized,
A method for producing a highly concentrated coal-water slurry, characterized in that additives are supplied in multiple stages in the direction of coal pulverization within the tube mill. (2) A method for producing a highly concentrated coal-water slurry as set forth in claim 1, characterized by supplying an additive in powder form to adjust the slurry concentration. (3) In claim 1, there is a plurality of wet tube mills or a large number of tube mills, and the amount of addition is determined according to the surface area of the coal pulverized in each tube mill or in each chamber. 1. A method for producing a highly concentrated coal-water slurry, which comprises supplying a highly concentrated coal-water slurry.