JPS62169890A - Production of highly concentrated coal slurry - Google Patents

Abstract

PURPOSE:To prevent the clogging of a nozzle of a burner and lowering in combustion efficiency of a boiler, by pulverizing coal with a pulverizer, classifying the pulverized coal with a suspension classifier to remove coarse particles, and preparing a highly concentrated coal slurry using only finely divided particles. CONSTITUTION:A pulverizer 1 is charge with coal a and water b. The mixture is wet pulverized to obtain a coal powder slurry in which coarse particles are mixed with finely divided particles. The coal powder slurry is fed into a suspension classifier 7 together with a surfactant e and a foaming agent f, followed by stirring. Only finely divided particles is allowed to float by taking advantage of the caused buoyancy while coarse particles are precipitated. Only finely divided particles are overflown together with bubbling water, passed through a stirring vessel 5 and fed into a dehydrator 3 for dehydration treatment. The dehydrated finely divided particles are fed into a kneader 4 and mixed with a predetermined amt. of a surfactant c, followed by kneading, thereby obtaining an intended highly concentrated coal slurry. The highly concentrated coal slurry thus obtd. is suited for use as a fuel of a boiler, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field This invention relates to a method for producing a highly concentrated coal slurry used in thermal power generation and the like.

(2) Conventional technology Figure 3.4 shows the conventionally common high concentration coal slurry (CWM).
). In the drawings, 1 is a crusher, 2 is a mechanical sieve such as a vibrating screen or sieve bend, 3 is a dehydrator such as a filter, and 4 is a mixer. In pulverizer L, coal A is added with water and subjected to wet conversion.

-200 mesh, crushed to about 80% or more.

This pulverized coal powder is classified by the sieve machine 2 to remove coarse particles, but this causes problems such as clogging of the mesh of the sieve machine 2, manufacturing limitations, and escaping of 200 mesh pieces on the sieve. , the opening of the mesh must be 200 meshes or more, and unnecessary coarse particles (for example, 0.5 mm or more) of +200 meshes will inevitably get mixed into the bottom of the screen, and such coarse particles should not be included. The slurry is supplied to the following equipment. Therefore, a slurry in which -200 mesh fine particles and +200 mesh coarse particles are mixed is supplied to dehydrator 3, dehydrated in dehydrator 3, and then sent to cross line Ja4, where a predetermined amount of surfactant C is added. Added solids concentration 65-7
Converts to CWM at around 0%. The CWM slurry d is then used as fuel for a boiler or the like.

(3) Problems to be Solved by the Invention By the way, since the CWM-formed slurry as described above contains coarse particles of +200 mesh, when it is burned by the burner supplied as fuel, the burner nozzle This has negative effects such as clogging the fuel and remaining unburned in the boiler, causing a reduction in combustion efficiency. As shown in FIG. 4, this can be explained by the sieving machine 2, dehydrator 3, etc. in FIG.
In place of the kneader 4, a concentration adjustment stirring tank 5 and a second pulverizer 6 are installed, and the slurry pulverized by the pulverizer 1 is introduced into the concentration adjustment stirring tank 5, stirred in the stirring tank 5, and then The same thing can be said for the manufacturing method in which surfactant C is added before introduction into the second pulverizer 6, and the second pulverizer 6 grinds the slurry even more finely, and even in this case, coarse particles of +200 mesh are mixed into the slurry. It was impossible to prevent this.

Therefore, the technical object of the present invention is to ensure that the coarse particles can be removed from the coal powder that has been crushed by a pulverizer before being supplied to downstream equipment.

(4) Means for Solving the Problems In order to solve the above-mentioned problems, the method for producing high-grade coal slurry of the present invention uses coal powder in which coarse particles are mixed with fine particles crushed by a pulverizer. The coal powder is introduced into a floating classifier, coarse particles are removed from the coal powder by classification by the floating classifier, and then a highly concentrated slurry containing only fine particles is supplied to downstream equipment.

(5) Embodiments In the embodiments shown below, the same members as those in the conventional system are given the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 shows one embodiment of the invention. In the drawing, 7 is a floating classifier that is installed between the crusher 1 and the stirring tank 5 and uses the buoyancy of air bubbles. It is added in an amount that suspends the desired particle size, and the desired amount of bubbles is generated by stirring.

Then, the particle size to be recovered is controlled so that coarse particles (0.5 mm or more) of +200 mesh do not come into contact with air bubbles and float.

Coarse particles in the slurry are not suspended, and only fine particles are suspended.

This will be explained in more detail. When a stirring blade (rotor) is rotated to stir the surfactant e and the foaming agent f in the tank of the classifier l containing the surfactant e and the foaming agent f, fine bubbles are generated in the tank due to the air and the foaming agent f. When a slurry containing coarse particles crushed by a crusher 1 is introduced into a tank in which a desired amount of bubbles have been generated, the coarse particles in the slurry will settle to the bottom of the tank, leaving only fine particles. comes into contact with the bubbles and floats up, overflows and is collected together with the bubble water and introduced into the stirring tank 6. Particle size classification is fully possible when the solids concentration of the slurry introduced into the tank is in the range 15-50%. In addition, coarse particles that have settled to the bottom of the tank are removed by appropriate means.

In this way, the slurry containing the coarse particles pulverized by the milliliter is supplied to the downstream equipment after the +200 mesh coarse particles are removed by the classifier 7, and a slurry containing only the -200 mesh fine particles is supplied to the downstream equipment. Therefore, the slurry that has been converted into CWM after passing through the stirring tank 5° dehydrator 3 and kneader 4 as downstream equipment is used as fuel for boilers etc. in a highly concentrated state with a solids concentration of about 65 to 70%, as in the past. It becomes a high quality fuel.

FIG. 2 shows a different usage mode of the embodiment shown in FIG. 1, in which the kneading machine 4 in FIG. 1 is replaced.

A second crusher 6 is installed. Even in such use, the floating classifier 7 performs the same classification as described above,
There is no change in the quality of the CWM slurry that has passed through the second crusher 6.

(6) Effects of the Invention As described above, according to the present invention, before supplying coal powder in which coarse particles are mixed with fine particles crushed by a crusher to downstream equipment,
After the coarse particles are removed by classification using a 1% free classifier, it is supplied as a highly concentrated slurry containing only fine particles, so even if the CWM slurry is used as fuel for boilers, there will be no clogging of burner nozzles or combustion. It has an excellent effect in that it can completely eliminate the conventional problems such as causing a decrease in efficiency.

[Brief explanation of drawings]

Figure 1 is a flow sheet showing one embodiment of this invention;
The figure is a flow sheet showing a different usage pattern from Figure 1.
The figure is a flow sheet showing a conventional example, and FIG. 4 is a flow sheet showing a different usage mode from FIG. l...Crusher 2...Sieving machine 3...Dehydrator 4...Kneading machine 5...Concentration adjustment stirring tank

Claims (1)

[Claims] 1. Coal powder, which has been crushed by a pulverizer and has coarse particles mixed with fine particles, is introduced into a floating classifier, and after the coarse particles are removed from the coal powder by the classification of this floating classifier, a highly concentrated slurry containing only fine particles is produced. A method for producing a highly concentrated coal slurry, characterized in that the slurry is supplied to downstream equipment as a slurry.