JPS59210996A - Preparation of deashed coal/oil slurry - Google Patents

Abstract

PURPOSE:To increase the efficiency of coal refining and deashing independently of variation in particle size distribution of raw material coal, by classifying coal into ash-rich and low ash lots by flotation of dust coal, deashing the two lots separately and preparing a slurry of a mixture of the two lots. CONSTITUTION:A frother 24 and a collector 25 are added to a slurry composed of dust coal 41 and water 44 in a conditioning tank 4. The slurry is fed into a flotation machine 1 for separation into refined coal 11 with a low ash content and tailing 12 with a high ash content. The refined coal 11 is sent into an oil- extension granulator 53 for addn. of heavy fuel oil 27, granulation and preparation of deashed coal 42, while the tailing 12 is sent into the oil-extension granulator 53 for addn. of heavy fuel oil 27, deashing, granulation and preparation of deashed coal 21. The coal 42 and coal 21 are fed into a coal/oil slurry making tank 3, where heavy fuel oil 27 and surfactant 26 are mixed into the coal for formation of a coal/oil slurry 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a deashed coal-oil slurry.

Coal contains ash, and when burned in a boiler,
It is preferable to remove as much ash as possible before combustion, since this will cause a reduction in boiler efficiency. Also, by making the residual ash content in coal the same for each type of coal, it is possible to minimize variations in calorific value and combustion efficiency depending on the type of coal. Based on this background, a method for producing coal/heavy oil slurry incorporating a conventional deashing process will be explained with reference to FIG.

Raw coal 50 is put into a raw coal receiving tank 31 and supplied to a coal crusher 33 by a quantitative feeder 32. Approximately 30 for coal crusher 63
~50 m of raw coal 30 is crushed into approximately 3 mm or less pure coal 34. This pure coal 34 is separated by a screen 35 into 5- or more coal 57 and 6- or less coal 36.
Smaller coal 36 is stored in a pure coal receiving tank 38. ,
! The coal 37 of 1111 m or more is returned to the raw coal receiving tank 31 again. The coal 36 smaller than 6th coal stored in the pure coal receiving tank 38 is fed into a pulverizer (
Pulverized coal 41 such as 200 mesh pass 70-95% is supplied to a wet pulverizer 40 and mixed with water 43.
finely pulverized. The pulverized coal 41 is received in a pulverized coal storage tank 42 in the form of a coal-water slurry (coal concentration of approximately 45 to 55% by weight).

Then, the pulverized coal 41 is transferred to a dehydrator 2 after the flotation machine 1, which will be described later.
The water concentration is adjusted to about 20 to 30% by weight using the water 14 separated from the water 14, and the water is supplied to the condition tank 4 together with the foaming agent 24 and the collecting agent 25, and then sent to the flotation machine 1 to produce coal with a low ash content ( It is divided into pulverized coal 11 and coal with a high ash content (tail) 12.

Coal (tail) 12 with a high ash content is sent to a wastewater treatment facility and disposed of.

Coal with a low ash content (Pf coal) 11 is reduced to approximately 2
The water 14 separated from the dehydrator 2 is reused to adjust the concentration of the pulverized coal 41 supplied to the conditioning tank 4 as described above. The cake-like powdered coal 13 having a moisture content of approximately 20% by weight is adjusted in a slurry adjustment tank 3 with a surfactant 26 and a heavy oil 27 to a final coal concentration of a coal/heavy oil slurry 15 of approximately 50mM% coal/heavy oil main content and 150% by weight.

The above is a coal/heavy oil slurry production method incorporating a conventional deashing process. Here, in the conventional deashing process, pulverized coal 41 having a wide particle size range is simultaneously treated in the condition tank 4 and sent to the flotation machine 1. The relationship between the charcoal recovery rate and the deashing rate is as shown in Figure 2.If you try to improve the ashing rate, the charcoal recovery rate will decrease. Therefore, it can be seen that the recovery rate of coal (pulverized coal) 11 with a low ash content suddenly deteriorates.

Figure 2 shows Daido coal (particle size 200 mesh pass 80%) after 7 minutes of residence time in the conditioned tank, pH 6-82 coal thick coal-8 in a Fahrenwald flotation machine, and kerosene used as a collector for 7 minutes. This is the result of flotation.

In this IT, the amount of coal (powdered coal) 11 with a low ash content is small, so the amount of raw coal 3o to be supplied must be increased, the coal (tail) 12 with a high ash content increases, and the load on the wastewater treatment equipment increases.
This is a defect.

Therefore, the present inventor completed the present invention as a result of intensive research in order to develop a process that efficiently maintains the pulverized coal recovery rate and deashing treatment efficiency even when there are fluctuations in the coal particle size distribution.

That is, the present invention grinds coal to a particle size suitable for coal-tomo slurry, passes it through a flotation machine, and separates the flotated coal with a low ash content and the coal with a high ash content generated from the tail of the flotation machine. and a method for producing a deashed coal-oil slurry, which comprises deashing each using an oil-hot granulation device, combining the two, adding heavy oil and a surfactant thereto, and stirring and mixing them. It is.

A specific embodiment of the present invention will be described below with reference to FIG. In FIG. 3, the steps in the pulverized coal storage tank 421 explained in connection with FIG. 1 are the same, so they are omitted.

That is, the pulverized coal 41 is adjusted to a concentration of about 20 to 60% by water 44, and a foaming agent 24. Collection agent 2
5 and introduced into the flotation machine 1. Here, coal is divided into coal with a low ash content (shank coal) 11 and coal with a high ash content (tail coal) 12. Coal (tail) 12 with a high ash content is introduced into an oil-added granulator 53. Binder like heavy oil 27
will also be introduced at the same time.

A specific example of the oil temperature granulation device 53 is shown in FIG.

Figure 4 shows coal with a high ash content (tail) 12 from flotation machine 1.
Alternatively, the case is shown in which the present invention is applied to coal (pulverized coal) 11 with a lower ash content than the flotation machine 1. That is, a binder 27 such as heavy oil is passed through the binder nozzle 54, or coal with a high ash content (tail) 12 or coal with a low ash content (pulverized coal) from the flotation machine 1 is fed.
11 is introduced into an oil-added granulator 56 through a nozzle 55, and is stirred by an agitator 52 driven by an electric motor 51.

The coal content in coal with a high ash content (tail) 12 or the coal with a low ash content (pulverized coal) 11 and the heavy oil-like binder 27 are mixed into the agitator 5.
Due to the stirring action of step 2, the particles coalesce and grow into even larger particles.

At this time, since the ash does not combine with the binder 27 such as heavy oil, the ash can be separated from the combined particles of the coal and binder 27. When the slurry in such a state is applied from the nozzle 56 through the line 2° or 40 to the screen 45 or screen 5K, the combined particles of coal and binder 27 are separated at the top of the screen, and the ash is separated along with moisture at the bottom of the screen, and the line is separated. It is discharged through 22 and can be deashed.

Table 12 shows an example of operation data for such an oil temperature granulation device 53.
It is shown in Table 2.

Table 1 shows the high ash content coal (tail) 12 from flotation machine 1.
Table 2 shows the data when coal (pulverized coal) 11 with a low ash content from flotation machine 1 was granulated at oil temperature.

(Remarks) The operating data in Tables 1 and 2 are under the following conditions.

Type of 0 heavy oil: Middle East C heavy oil 0 oil additive granulation equipment: 400 nodal diameter x 1.000 - height effective capacity approximately 100t Impeller: 500 nodal diameter x 70 width x 4 straight blades x 2 stages Operation data in Table 1 By introducing the coal (tail) 12 with a high ash content from the flotation machine 1 into the oil-added granulator f (f 53), the coal content in the coal (tail) 12 with a high ash content can be removed with high efficiency. It can be recovered.

It goes without saying that the heavy oil addition rate, coal recovery rate, etc. differ depending on the type of coal, but the advantage of this method is that the coal can be recovered with high efficiency and with little residual ash (,・tsu), which can be applied to a wide range of coal types.

The thus recovered coal (in a state where the coal is granulated with a binder such as heavy oil) 21 is sent to the coal/oil slurry manufacturing tank 5.

In addition, the operating data in Table 2 shows that coal with a low ash content from flotation machine 1 (
The case is shown in which powdered coal) 11 is further deashed by introducing it into an oil hot granulation device 55. This deashed coal 42 is also sent to the coal/oil slurry production tank 3. In a coal/oil slurry production tank 3, coal 21, deashed coal 42, heavy oil 27, and a surfactant 26 such as sodium alkylnaphthalene sulfonate are stirred and mixed to form a coal/oil slurry 15. .

The granulated coal 21.41 from the hot oil granulator 56 in the coal/oil slurry production tank 5 is disintegrated to improve the combustion efficiency of the coal/oil slurry 15.

In this way, a deashed coal/oil slurry is produced that has a high coal recovery rate and can be applied to a wide range of coal types. The coal concentration in the coal/oil slurry 15 is adjusted to about 50% (by weight) by the heavy oil 27.

The method of the present invention has a higher coal recovery rate than the method of directly subjecting pulverized coal to hot oil granulation without flotation.
It has the expected effect of a large and high demineralization rate. In other words, oil hot granulation alone provides a high coal recovery rate, but does not provide a very high deashing rate. For example, according to the method of the present invention when flotation is performed under the conditions under which the data related to FIG. 2 was taken, and then granulation is separately performed by lottery, the coal recovery rate is 99%.

The deashing rate was 77%, but when the same coal was used directly as an oil additive without being subjected to flotation, the coal recovery rate was 99% and the deashing rate was 4.
It was only 2%.

[Brief explanation of the drawing]

Figure 1 is a flowchart of a coal/oil slurry manufacturing method incorporating a conventional deashing process, Figure 2 is a graph showing the relationship between deashing rate and coal recovery rate in a flotation machine, and Figure 3 is a graph showing the relationship between deashing rate and coal recovery rate in a flotation machine. Flow of one embodiment of the present invention, FIG. 4 shows a schematic diagram of an oil hot granulation apparatus for carrying out the method of the present invention. Sub-Agents 1) Meifuku Agent Ryo Hagiwara - Figure 1

Claims (1)

[Claims] Coal is crushed to a particle size suitable for coal-oil slurry, and then passed through a flotation machine to separate the flotated coal with a low ash content and the coal with a high ash content generated from the tail of the flotation machine. A method for producing a deashed coal-oil slurry, which comprises deashing the slurry using an oil hot granulator, combining the two, adding heavy oil and a surfactant, and stirring and mixing.