JPH09310079A - Modification of coal and production of cwm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To modify coal into such coal as to be high in calorific value as a fuel because of its low volatility of the volatiles even if dried and suitable for producing highly concentrated and highly fluid coal-water slurry, by drying pulverized coat at a specific temperature followed by addition of tar to conduct a non-waterabsorbing treatment. SOLUTION: Pulverized coal (ground to e.g. <=5mm, esp. <=500μm in particle size) is dried by heating to 180-230 deg.C in a nonoxidative atmosphere such as in a vacuum, nitrogen, carbon dioxide or combustion exhaust gas followed by addition of tar such as coal tar and then further heating to 200-300 deg.C to effect adhesion of the tar to the surface of coal particles, thus conducting a nonwater-absorbing treatment of the coal. Specifically, for example, low-grade coal is ground by a mill 1, introduced into a vacuum paddle dryer 3, and the inside of the dryer 3 is brought to a vacuum by a steam ejector 4; the pulverized coal is then dried under heating at a prescribed temperature while agitating it with a paddle 3a; subsequently, molten tar is introduced, via a pump 6, into the vicinity of the exit of the dryer 3 and agitated with the paddle 3a, thus coating the coal surface with the tar.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reforming coal and a method for producing CWM, and more particularly, a method for drying coal and then performing non-water-absorption treatment, and production of CWM (coal / water slurry) using the method. Regarding the method. More specifically, a coal reforming method and CWM improved so that the treatment temperature is relatively low.
And a method for producing the same.

[0002]

2. Description of the Related Art As a method of non-water absorption treatment after drying coal, it is crushed at 270 to 330 ° C. and 80 to
Method for dehydrating coal (treatment for removing water from coal particles) and non-water-absorbing treatment by holding under hot water conditions of 150 kg / cm ² for 10 to 30 minutes, and coal powder thus treated A method for dispersing CWM in water to produce CWM is known (5th Coal Utilization Technology Conference Lecture Collection (September 1995). Sponsored Coal Utilization Center,
Sponsor: Agency for Natural Resources and Energy).

When coal is heated to 300 ° C. or higher,
With the loss of water, the tar content contained in the coal becomes liquid and oozes out on the surface of the coal particles to block the pores on the surface of the coal particles, which reduces the specific surface area of the coal and decreases the hygroscopicity. Are known (for example, Japanese Patent Publication No. 57-1).
1596).

[0004]

In the above drying and non-water-absorption treatment of coal, the heating temperature is as high as 270 ° C. or higher, the volatilization of volatile components in the coal increases, and the calorific value of coal decreases. There is a great risk of doing so.

It is an object of the present invention to provide a coal reforming method capable of drying and non-water absorbing treatment of coal at a lower temperature than before, and a CWM manufacturing method using the same.

[0006]

According to the method for reforming coal of the present invention, pulverized coal is heated to 180 to 230 in a non-oxidizing atmosphere.
It is characterized in that it is heated to ℃ and dried, and then tar is added to carry out a non-water absorption treatment for adhering the tar to the surface of the coal particles. The method for producing a CWM according to the present invention is one in which coal powder is modified by this modifying method and then dispersed in water to obtain a CWM.

The method for producing CWM according to the present invention comprises the steps of modifying coal powder by this modifying method and then dispersing it in water to form CW.
It is assumed to be M.

In the coal reforming method of the present invention, since the heating temperature is 180 to 230 ° C., which is considerably lower than the conventional temperature,
Volatile components also remain sufficiently. When the heating temperature is low, the tar-like substance hardly oozes out from the inside of the coal particles to the surface, but by adding tar from the outside, it is possible to cover the coal particle surface with tar and dewater the coal. it can.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the coal type of coal is not particularly limited, but the present invention is suitable for application to the treatment of low-grade coal such as brown coal which has not been used so far.

In the present invention, coal is first crushed to 2 mm or less, preferably 500 μm or less. Then, it is heated to 180 to 230 ° C. in a non-oxidizing atmosphere and dried. As the non-oxidizing atmosphere, in addition to vacuum, nitrogen, carbon dioxide gas, combustion exhaust gas or the like can be used.

If the drying temperature is lower than 180 ° C., the moisture will be insufficiently removed. On the other hand, when the temperature is higher than 230 ° C, the amount of volatile components volatilized increases. The preferred drying temperature is 190 to 220 ° C.

After this drying treatment, tar (preferably coal tar) is attached and heated to coat the surface of the coal particles with tar. The amount of tar added is 10 to 10 with respect to 1 kg of coal.
It is preferably 0 g, especially about 10 to 20 g. After adding tar (or from the stage before adding tar)
By heating the coal to 200 to 300 ° C., preferably 230 to 270 ° C., tar covers the surface of the coal particles and the coal becomes non-water absorbent. In addition, FIG.
When the drying and the non-water-absorption treatment are performed in the same chamber as in the apparatus of No. 3, the drying temperature and the non-water-absorption treatment temperature are almost the same.

After the non-water absorption treatment, the coal powder is dispersed in water to obtain CWM. At this time, it is preferable to add an additive such as a dispersant. Since the coal particles are hardly absorbed by the non-water absorption treatment, CW
When M is set, the coal concentration in CWM can be set to 60% by weight or more while maintaining a sufficiently low viscosity.

1 to 3 are schematic flow charts of an apparatus for reforming low-grade coal by the method of the present invention.

In the reformer of FIG. 1, low-grade coal is crushed by a mill 1 and introduced into a vacuum paddle dryer 3 through a lock hopper 2. The coal is heated and dried in the vacuum paddle dryer 3 by a heat source such as steam while being stirred by the paddle 3a.
The inside of the vacuum paddle dryer 3 is sucked by the steam ejector 4 to bring the inside into a substantially vacuum state. Molten tar is introduced near the outlet of the vacuum paddle dryer 3 through the tank 5 and the pump 6 and well stirred by the paddle 3a to cover the coal surface with tar. After that, coal is taken out from the vacuum paddle dryer 3 via the lock hopper 7 and sent to the slurry tank 8 to be used as CWM.

In the reformer of FIG. 2, the low-grade coal is milled 10
It is pulverized in (1) and introduced into the reduced pressure fluidized bed reactor 12 via the lock hopper 11. The inside of the reduced pressure fluidized bed reactor 12 is sucked by the steam ejector 13 and heated by a heat source such as steam. Nitrogen obtained by separating air by the acid nitrogen separator 14 is introduced into the reduced pressure fluidized bed reactor 12. The coal which has been subjected to the fluidized drying treatment in the reduced pressure fluidized bed reactor 12 receives the addition of the molten tar and then the lock hopper 15
And the surface of the coal is covered with tar, and then introduced into the slurry tank 16 to become CWM. The CWM is sent to the partial oxidation gasification furnace 17, where it is partially oxidized by oxygen from the oxy-nitrogen separator 14 to generate gas such as H ₂ and CO.

In the reformer of FIG. 3, the low-grade coal is mill 20.
It is crushed in the
Are supplied to the individual reactors 22. The inside of the reactor 22 is sucked by the steam ejector 23 and is in a substantially vacuum state. Molten tar is added into the reactor 22, and the surface of coal is covered with tar. This coal is sent to the slurry tank 25 by the rotary recovery machine 24, and the CWM
Becomes

[0018]

【Example】

Examples 1-4, Comparative Examples 1-3 Brown coal having the following industrial analysis values was modified according to the method of the present invention.

Industrial analysis value of test lignite Total moisture (TM) 34.1% Moisture (IM) 17.5% Ash (A) 4.6% Volatile (VM) 38.7% Fixed carbon (FC ) 39.2% Sulfur content (S) 1.91% Calorific value (CV) 5335cal / g First, this brown coal was pulverized to 500 μm or less, and 20 g thereof
Was heated for 2 hours at the following temperature at 0.5 Torr in a vacuum heating furnace (electric furnace).

Heating Temperature Comparative Example 1 170 ° C. Example 1 180 ° C. Example 2 200 ° C. Example 3 220 ° C. Example 4 230 ° C. Comparative Example 2 250 ° C. Comparative Example 3 270 ° C. Once the temperature inside the furnace was lowered, The lignite was taken out, 0.3 g of coal tar was lightly mixed with the heat treated lignite, then returned to the furnace and heated to the temperature shown in Table 1 for each example to coat the lignite surface with the coal tar (coal tar. processing).
At this time, the pressure inside the furnace was set to 20 atm.

After 30 minutes, the sample was taken out and immersed in water at room temperature for 48 hours to measure the amount of water absorption.

For comparison, the same applies to the heat-treated brown coal before the coal tar treatment in Examples 1 to 4 and Comparative Examples 1 to 3 (only the brown coal was heat-treated at 170 to 250 ° C.). The amount of water absorption was measured.

The results are shown in Table 1. The amount of water absorbed is the amount of water absorbed (g-
It is shown as water / 100 g-coal).

Table 1 also shows the weight reduction rate due to the above-mentioned drying.

[0025]

[Table 1]

From Table 1, it is clear that according to the examples of the present invention, the drying is sufficiently performed, the water absorption rate is low, and the reduction of volatile matter is extremely small.

In Comparative Example 1, the drying temperature is low and the drying is slightly insufficient. It can be seen that in Comparative Examples 2 and 3, the drying is sufficient, but the volatilization of the volatiles is large.

Next, the brown coal powders obtained in the above Examples 1 to 4 after the coal tar treatment were each mixed in a ball mill in an amount of 3 times.
It was dispersed in water by stirring for 0 minute to obtain CWM, and the viscosity was measured. The coal concentration should be 50-65%.
A CWM was experimentally manufactured with various changes. Then, when the relationship between the coal concentration and the viscosity of the CWM was determined in each example, the results are shown in Table 2 below.

[0029]

[Table 2]

As is clear from Table 2, the CW of each example
M shows sufficient fluidity even in the high concentration region where the coal concentration is 60 to 65%. This is because the coal particles hardly absorb water, and the water is present exclusively between the coal particles.

[0031]

As described above, according to the method for reforming coal of the present invention, it is possible to dry the coal at a lower drying temperature than before and to carry out the non-water absorption treatment. Therefore, the volatilization of coal volatiles is small due to drying, and the calorific value of the obtained fuel is also high. Further, since the processing temperature is low, the operation becomes easy.

According to the present invention, a CWM having a high concentration and a high fluidity can be obtained from the coal thus modified.

[Brief description of drawings]

FIG. 1 is a systematic diagram of an apparatus suitable for carrying out the method of the present invention.

FIG. 2 is a system diagram of another apparatus suitable for carrying out the method of the present invention.

FIG. 3 is a schematic diagram of yet another apparatus suitable for carrying out the method of the present invention.

[Explanation of symbols]

 1,10,20 mil 3 Vacuum paddle dryer 4,13,23 Steam ejector 2,7,11,15 Lock hopper 8,16,25 Slurry tank 17 Gasification furnace

Claims (2)

[Claims] 1. Crushed coal in a non-oxidizing atmosphere 18
A method for reforming coal, which comprises heating to 0 to 230 ° C. to dry it, and then performing a non-water-absorption treatment in which tar is added to deposit the tar on the surface of the coal particles. 2. A method for producing CWM, characterized in that coal powder is dried and non-water-absorbing treated by the reforming method of claim 1, and then dispersed in water.