KR101546369B1 - Production of Coal water fuel and coal water fuel produced by the same - Google Patents

Abstract

The present invention relates to a method for producing a coal-water mixed fuel and a coal-water mixed fuel produced thereby, and more particularly, to a coal-water mixed fuel produced by using a high- And a coal-water mixed fuel produced by the method. The method of the present invention comprises the steps of crushing coal; Drying the pulverized coal using a drier; Pulverizing the coal after the drying step using a pulverizer; And mixing the water and an additive in the finely pulverized coal, wherein the coal dried by using the zigzag type dryer using the multiple interrupting plates according to the present invention is changed in properties to be hydrophobic , The solid content of the coal-water mixture fuel is increased by more than 10 wt% compared to the raw coal.

Description

[0001] The present invention relates to a method for producing a coal-water mixed fuel and a coal-

The present invention relates to a method for producing a coal-water mixed fuel and a coal-water mixed fuel produced thereby, and more particularly, to a coal-water mixed fuel produced by using a high- To a method for producing a mixed liquid fuel and to a coal-water mixed fuel produced by the method.

Efforts are continuing to secure energy sources that can replace crude oil in the short term in preparation for rising crude oil prices and mid- to long-term crude oil depletion. Recently, researches on new energy sources that can replace existing fossil fuels such as solar energy and bio energy have been actively carried out, but there is still a limit to industrial use. As a result, demand for coal is increasing again. In Korea, coal is being imported from overseas countries such as Australia and Indonesia because most mines are abandoned.

Coal is divided into peat, brown coal, lignite, sub-bituminous coal, bituminous coal and anthracite grades, and bituminous coal is further divided into low volatile matter, , Anthracite coal, anthracite coal, meta-anthracite coal and graphite anthracite coal. Among these, brown coal to bituminous coal is converted to low grade coal (LRC) and bittern coal is converted to high grade coal (HRC) .

High-grade coal, such as semi-anthracite and bituminous coal, should be used to directly generate coal by burning it. However, since bituminous coal and semi-anthracite coal are expensive and reserves are small, studies have been conducted since the 1980s to utilize low grade coal (LRC: Low Rank Coal), which has relatively rich reserves and low prices, with high quality.

For example, lignite, which is one of the low-grade coal, is low in price compared to bituminous coal, but has a water content of 30 to 70% and a low calorific value of 2500 to 4000 kcal / kg, to be.

In order to solve this problem, studies on low-grade coal drying such as simple drying of low-grade coal, high-pressure drying using hot water, or drying using a high-temperature organic solvent have been actively carried out. However, there is a problem in that the process is complicated, There is still a problem that the power generation efficiency is lowered due to adsorption. In addition, there is a problem in that spontaneous ignition occurs when moisture is reabsorbed in dried coal, and thus stored coal is lost [M. Morimoto et al., Energy Fuels, 2009, 23, 4533; D.J. Allardice et al., Fuel, 2003, 82, 661].

Therefore, one of the most important problems to be solved in order to promote the use and distribution of low grade coal is to prevent the re-adsorption of moisture to the dried low grade coal, to maintain the calorific value and to suppress the spontaneous combustion . One of the technologies that can overcome such problems is a method of removing the intrinsic moisture of coal by heating a low grade coal using a high temperature organic solvent in a high pressure atmosphere. However, this technique has a disadvantage that the organic solvent must be separated and recovered, the process is relatively complicated, and another energy cost is required, so that a simpler and more effective technique for suppressing moisture adsorption of dry charcoal is required.

In addition, the classification layer coal gasification is classified into a dry classification layer and a wet classification layer. The wet classification layer gasification is lower in apparatus construction cost than the dry method, the apparatus structure and operation method are simple, and the supply of coal slurry is easy However, in spite of these various advantages, since the water content is additionally included in the slurry used as the wet gasification raw material in the case of the wet type, the calorific value of the coal slurry is lower than that of the dry type using the raw coal, There are disadvantages. Therefore, in order to compensate for these drawbacks, a high concentration of coal slurry should be produced, but in general, low-grade coal has a low intrinsic moisture content and therefore low coal slurry concentration.

Korean Patent Laid-Open No. 10-2010-0096432 discloses a method for producing a mixed fuel of coal and water including a cavitation generating process and a high-frequency treating process, and a mixed fuel technique of coal and water produced by this manufacturing method. However, this technique has a problem that it is difficult to obtain a coal slurry having a high concentration. Korean Patent No. 10-1195417 discloses a method for producing a high-concentration hybrid coal slurry and a technique for the high-concentration hybrid coal slurry produced thereby. However, the above-mentioned technique should add a process of coating the hydrophilic surface of coal with carbon component to prevent reabsorption of water in the process of producing coal slurry.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for producing a high-strength coal which has a hydrophilic surface in a low grade coal, - water mixed fuels and to provide a high concentration coal-water mixed fuel produced thereby.

In order to solve the above problems, the present inventors have found that coal dried using a zigzag drier using a multi-disturbing plate has hydrophobicity and can produce a high-concentration coal-water mixed fuel by mixing water and additives after pulverizing the coal. And completed the present invention.

The present invention relates to a method for pulverizing coal, Drying the pulverized coal using a drier; Pulverizing the coal after the drying step using a pulverizer; And mixing the finely pulverized coal with water and an additive.

The present invention also provides a method for producing a coal-water mixed fuel, wherein the coal is any one selected from peat, brown coal, lignite and sub-bituminous coal.

The present invention also provides a dryer in which the coal is dropped from the upper portion and the hot air is injected from the lower portion to dry the coal, wherein the dryer has a plurality of baffles having a downward gradient formed in a zigzag shape, And then dried and then dried in a zigzag manner along the obstruction plate.

The present invention also provides a method for producing a coal-water mixed fuel, wherein the pulverizer is selected from the group consisting of roll mill, pin mill, hemmer mill, ball mill and wet mill.

The present invention also provides a method for producing a coal-water mixed fuel, wherein the size of the coal particles passed through the pulverizer is 250 μm or less, and the weight ratio of the particles to the particle size of 75 μm or less is 60%.

The present invention also provides a method for producing a coal-water blended fuel, wherein the additive is a surfactant and 0.1 to 2 wt% of the weight of the coal.

The present invention also provides coal-water mixed fuels produced by the process of any one of claims 1 to 6.

According to the present invention, the dried coal using a zigzag type dryer using a multi-disturbing plate changes its property to be hydrophobic, and the solid content of the coal-water mixture fuel is increased by at least 10 wt% compared to the raw coal.

FIG. 1 is a conceptual view of a process for producing a high-concentration coal-water mixed fuel according to the present invention.
Fig. 2 is a conceptual diagram of a zigzag type dryer using the multiple disturbance plate used in the present invention.
Fig. 3 shows measured values of contact angle of raw coal and dry coal indicating whether or not coal is reabsorbed.
4 is a graph showing the solid content of the coal-water mixed fuel according to the drying / stabilization temperature.

Hereinafter, the method for producing the coal-water mixed fuel according to the present invention and the coal-water mixed fuel produced thereby will be described in detail. The present invention relates to a technique for producing a high concentration of coal-water blended fuels by using a high-moisture coal dried with a reverse flow multi-distil plate dryer.

As shown in FIG. 1, low-grade coal is pulverized, dried, pulverized, and water and additives are mixed with the pulverized coal to produce a coal-water mixed fuel. In one embodiment of the present invention, the low grade coal may be any one selected from peat, brown coal, lignite and sub-bituminous coal.

In one embodiment of the present invention, the dryer is a reverse flow multiple disc plate dryer as described below. The coal dried in the dryer is subjected to a pulverization process. In one embodiment of the present invention, the pulverization process is performed using a roll mill, a pin mill, a ball mill, a wet mill, or the like, and both dry grinding and wet grinding are applicable. In one embodiment of the present invention, the size of the coal particles subjected to the finely pulverizing process is 250 탆 or less, and the particle size of 75 탆 or less is about 60%.

A surfactant is used to improve the dispersibility of the coal-water mixed fuel after the above-mentioned pulverization process. In one embodiment of the invention, the surfactant ranges from 0.1 to 2 wt% of the weight of coal used. Water and surfactant are mixed with a certain amount of coal and stirred. As the agitation time passes, the coal-water mixture is made and the viscosity is measured using a viscometer. The viscosity is based on 1,000 cP, and when it exceeds, water is added. When the viscosity is 1,000 cP or less, the viscosity is measured by adding coal and a surfactant. The weight percentage of coal when the viscosity is 1,000 cP is the solid content of coal.

Figure 2 shows the reverse flow multiple disc plate dryer used in the present invention. The dryer is a dryer in which coal is dropped from the upper portion and high temperature air is injected from the lower portion to dry coal. The dryer has a plurality of baffles having a downward gradient formed therein in a zigzag manner, And dried. According to the above method, since the coal falls in a zigzag manner, the contact time with air increases and the drying efficiency increases. Further, a barrier plate inclined downward to 20 to 80 °, preferably 30 to 60 ° is formed inside the dryer, and drying of the coal is promoted by the pressure gradient at the upper and lower portions of the barrier plate.

Example 1: Coal drying

The coal was pulverized into particles having a size of 10 mm or less, and then a high-grade coal having a high water content was dried using the dryer shown in FIG. 2. The results of industrial analysis and calorific value analysis of raw coal and dry coal were shown in Table 1 . The temperature of the dryer was 130 ° C to 300 ° C, and the flow rate of hot air was 1 m ³ / min. As the temperature of the dryer increases, the water content decreases, the volatile matter and the fixed carbon content tend to increase, and the calorific value increases in proportion to the drying temperature.

Industrial analysis and calorific value analysis of raw and dry coal moisture
(wt%) Volatile matter
(wt%) Fixed carbon
(wt%) Ash
(wt%) Calorific value Raw coal 29.9 35.7 31.1 3.3 4,331 kcal / kg 130 ℃ dried 17.9 40.5 34.7 6.9 4,998 kcal / kg 160 ℃ dried 11.5 44.3 37.2 6.9 5,346 kcal / kg 250 ℃ dried 9.6 43.5 39.2 7.7 5,439 kcal / kg 300 ℃ dried 5.7 45.5 41.7 7.1 5,701 kcal / kg

FIG. 3 shows the results of water adsorption experiments of raw coal and dry coal by contact angle measurement. For the contact angle measurement, each coal was prepared in the form of pellets, and the contact angle between the surface of the coal and the droplet was measured after dropping the droplet on the surface of the pellet. In the case of the raw coal, the initial droplet had a contact angle of 72.2 °, but it was absorbed when 3 seconds elapsed, and the contact angle was 0. In the case of dry charcoal, it has an initial contact angle of 93.5 °. After 3 minutes, it can be confirmed that the contact angle is 89.3 °, and the droplet is not absorbed and the shape remains intact. As a result, it was confirmed that dry charcoal changed into hydrophobic property that does not absorb water. By utilizing the characteristic that the dry coal is changed to hydrophobic, it is possible to prevent reabsorption of moisture without coating the surface of the dried coal with a separate carbon component.

Example  2: Manufacture of coal-water mixture fuel

The dried coal was used to produce a coal-water mixed fuel. In order to carry out the experiments, the coal samples were pulverized using a pulverizer. The same results can be obtained by using any of a roll mill, a pin mill, a hemmer mill, a ball mill and a wet grinder as the pulverizer. The size of the undifferentiated coal particles was set to 250 μm or less, and particularly, the particle size of 75 μm or less was prepared at about 60%.

Surfactants were used to improve the dispersibility in the production of coal - water mixed fuels. The surfactant is in the range of 0.1 to 2 wt% of the weight of the coal used. A certain amount of coal and water and a surfactant are mixed and stirred. As the agitation time passes, the coal-water mixture is made and the viscosity is measured using a viscometer. The viscosity is based on 1,000 cP, and when it exceeds, water is added. When the viscosity is 1,000 cP or less, the viscosity is measured by adding coal and a surfactant. The weight percentage of coal when the viscosity is 1,000 cP is the solid content of coal.

 4 shows the solid content of the coal-water mixed fuel produced according to the operating conditions of the dryer. The viscosity criterion was 1,000 cP for all conditions. Comparing the solid content of coal, the raw coal content was as low as 45%, and the solid content increased from 51% to 56% depending on the operating conditions of the multi-disturbance dryer.

Through the above method, the coal produced by the multi - disturbing plate dryer was improved in the solid content by up to 10 wt% higher than that of the raw coal in the production of the coal - water mixed fuel due to its hydrophobic properties.

Claims (7)

Pulverizing coal;
Drying the pulverized coal using a drier;
Pulverizing the coal after the drying step using a pulverizer; And
Mixing the finely pulverized coal with water and an additive,
The dryer is a dryer in which coal is dropped from the upper part and air is injected from the lower part to dry coal,
Wherein the dryer has a plurality of baffles which are downwardly inclined downward from 20 DEG to 80 DEG with a downward gradient therein,
The coal is staggered along the barrier plate and dried,
The air injected from the lower part is injected at a temperature ranging from 130 ° C. to 300 ° C. at a flow rate of 0.5 m ³ / min to 1.5 m ³ / min.
Mixing the water and the additive in the finely pulverized coal comprises mixing 51% to 56% of the solid coal in the whole mixture,
A method for producing a coal - water blended fuel.
The method according to claim 1,
Wherein the coal is one selected from the group consisting of peat, brown coal, lignite and sub-bituminous coal,
A method for producing a coal - water blended fuel.
delete The method according to claim 1,
Wherein the pulverizer is selected from the group consisting of a roll mill, a pin mill, a hemmer mill, a ball mill and a wet grinder.
A method for producing a coal - water blended fuel.
The method according to claim 1,
Wherein the size of the coal particles passed through the pulverizer is 250 탆 or less, and the weight ratio of the particles to the particle size of 75 탆 or less is 60%
A method for producing a coal - water blended fuel.
The method according to claim 1,
Wherein the additive is a surfactant and is 0.1 to 2 wt%
A method for producing a coal - water blended fuel.
delete

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