JPH0637627B2 - Method for preparing coal slurry - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for preparing a coal slurry containing ground coal, petroleum coke, and water, respectively.

(Prior art) When using coal as a fuel, in order to facilitate handling such as transportation and storage of this coal, and deashing as necessary to improve quality,
BACKGROUND ART Coal slurry is prepared by adding a proper amount of water and a small amount of additives (dispersing agent, stabilizer, etc.) to coal, pulverizing and mixing the coal.

In the above coal slurry, the pulverized coal concentration is 65% by weight.
In order to maintain good slurry characteristics in terms of fluidity, stability, etc. over a long period of time when a high concentration of about -80% is used, this coal slurry has a special pulverized coal particle size composition. Required. That is, pulverized coal is required to be distributed in a wide range in terms of particle size, and moreover, not only those having a large particle size to a minute particle size but also the packing density of the coal to be used is increased in order to increase the packing density. Depending on the type, for example 3 μm
Ultrafine powder of less than 3 to 15% is extremely required.

On the other hand, petroleum coke obtained as a by-product in the oil refining process has a high price per calorific value, and is therefore used in some industries as an alternative fuel for petroleum and coal.

(Problems to be Solved by the Invention) By the way, in general, coal is harder than other minerals, requires a large amount of power for crushing, and has a disadvantage that the parts of the crushing device are severely worn. Therefore, if it is attempted to obtain a large amount of ultrafine powder by pulverization as described above, the above-mentioned inconvenience will occur remarkably. For example, regarding the pulverization power, it depends on the type of coal, the pulverization system, etc., but on average, 30 to 50 kwh is required for 1 ton of coal (dry basis), which is considerably large as the production cost of the coal slurry. It is a thing.

On the other hand, petroleum coke is roughly classified into two types, delayed coke and fluid coke. Of these, delayed coke accounts for the majority of petroleum coke production, but although it has slightly better grindability than coal, it has a large amount of fixed carbon and a relatively low volatile content of 10 to 15%. Flammability as powdered fuel is not good. Further, the fluid coke is not suitable for being used as a fuel because it has a low volatile content and is extremely poor in pulverizability and therefore is powdered.

(Object of the Invention) The present invention has been made by paying attention to the above-mentioned various circumstances, and when a desired coal slurry is to be obtained, it is possible to use a small crushing power, and in the petroleum coke. Therefore, the purpose is to improve the flammability of delayed coke (hereinafter, simply referred to as petroleum coke) that has good grindability but does not have good flammability, thereby increasing the utility value as a fuel.

(Structure of the Invention) In order to maintain high-concentration coal slurry with good slurry characteristics in terms of fluidity and stability, it is necessary to make a part of the coal into ultrafine powder. The gist of the present invention is to reduce the proportion of pulverized coal in the above-mentioned ultrafine powder, and to compensate for it by petroleum coke, which easily produces fine powder by pulverization. The point is that I tried to raise it.

(Example) Hereinafter, the Example of this invention is described.

In general, petroleum coke has a fine grain size depending on the manufacturing process, has less power required for crushing than coal, and has a property of giving less abrasion to a crushing device. Therefore, in the case of crushing coal and petroleum coke, when the overall particle size has a predetermined distribution,
Both of them are pulverized so that the particle size of petroleum coke is smaller than the particle size of coal, that is, the proportion of pulverized coal in the ultrafine powder in the coal slurry is reduced, and the amount of fine powder of petroleum coke is increased by that amount. This will reduce the overall power requirements for grinding and will also reduce wear on the parts of the grinding equipment.

When the petroleum coke is pulverized as described above, the petroleum coke may be preliminarily pulverized, and the prepulverized petroleum coke may be pulverized together with coal to obtain a desired fine powder. Alternatively, coal and petroleum coke may be crushed separately, and then both crushed may be mixed with each other. Further, the crushing of coal may be performed wet, while the crushing of petroleum coke may be performed dry.

In any of the above methods, the same effect as described above can be obtained by making the particle size of petroleum coke finer than the particle size of pulverized coal.

Also, since petroleum coke has a low volatile content as described above,
There is also an advantage that it is difficult to explode even if it is dry fine powder during the manufacturing process of coal slurry. Further, since petroleum coke has a low price per calorific value, it is possible to reduce the manufacturing cost of the coal slurry according to the mixing ratio.

On the other hand, petroleum coke is finely pulverized when the coal slurry is burned, so that the flammability is remarkably improved. That is, in the initial stage of the combustion of the coal slurry, the mixed pulverized coal is burned and the atmospheric gas temperature is raised to facilitate the ignition of the petroleum coke, and once the combustion is started, the petroleum coke is burned as described above. Since coke is pulverized, the burnout time is short. Further, since the calorific value of petroleum coke per combustion is about 8500 kcal per kg, which is higher than that of coal, the calorific value of the coal slurry can be increased according to the mixing ratio of petroleum coke. Also, since petroleum coke generally has an extremely low ash content of about 0.5% or less,
Similarly, the ash content of the coal slurry can be reduced.

Next, more specific examples for preparing a coal slurry will be described.

(First Specific Example) FIG. 1 shows a first specific example. In the figure,
The petroleum coke 1 is supplied to a preliminary crusher 2 and preliminarily crushed by a dry method, and then classified into a coarse powder 4 and a fine powder 5 by an air classifier 3, and the coarse powder 4 is returned to the preliminary crusher 2. Be re-ground. Since the petroleum coke 1 is easily pulverized into fine powder, the preliminary pulverization allows the petroleum coke 1 to be easily pulverized on an industrial scale.

The fine powder 5 of the classified petroleum coke 1 is supplied to a crusher 9 together with coal 7, and both of these 5 and 7 are crushed and mixed by a low-concentration wet method using water 10 separately supplied to this crusher 9. To be done. The pulverized product is supplied to a wet classifier 11 such as a liquid cyclone and classified into a coarse powder 12 and a fine powder 13, and the coarse powder 12 is returned to the pulverizer 9 and re-pulverized.

In the above crusher 9, the petroleum coke 1 is already fine powder 5
Since this is supplied, it is easy for the pulverizer 9 to pulverize it into ultrafine powder, so that the amount of ultrafine powder of the coal 7 can be reduced accordingly.

The low-concentration slurry containing the petroleum coke 1 and the fine powder 13 pulverized to a predetermined particle size is supplied to the dehydrator 14 and adjusted to a predetermined water content. Further, this is mixed with an additive 17 by a stirrer 16 (or a kneading machine), and at the same time, a high-concentration coal slurry 18 having a predetermined fluidity is obtained by adjusting a necessary water content. Transported to the process.

(Second Specific Example) FIG. 2 shows a second specific example. In the figure,
The petroleum coke 1 is pulverized by a pulverizer 20 in a dry manner to obtain fine powder 21. On the other hand, the coal 7 is wet-milled separately from this by the pulverizer 22, and the pulverized coal 23 in the form of a low-concentration slurry obtained by this is supplied to the dehydrator 14 and adjusted to a predetermined water content. Then, the additive 17 is added to the fine powder 21 of the petroleum coke 1 and the fine powder 23 ′ of the coal 7, and these are mixed by the stirrer 16.

Further, the pulverized coal 23 from the classifier 11 is made into a high-concentration slurry-like or cake-like pulverized ash 23 'by the dehydrator 14, and at this time, the dehydrated wastewater 25 is returned to the crusher 22 for reuse. It has become.

According to the above configuration, the petroleum coke 1 and the coal 7 are individually pulverized, so that there is an advantage that the particle size of the respective fine powders 21 and 23 'can be easily adjusted. Moreover, since the dry powder 21 of the petroleum coke 1 is mixed with the pulverized coal 23 'after dehydration in the dehydrator 14, the pulverized coal 23' after dehydration may have a high water content. Therefore, the dehydration work in the dehydrator 14 is easy, and the power consumption for dehydration is small.

In this embodiment, the number of the stirrers 16 is one, but two stirrers 16 are arranged in series, and the additive 17 is added by the first stirrer 16 to add the high concentration pulverized coal 23 ′ from the dehydrator 14.
The second stirrer 16 may mix the pulverized coal 23 'with the dry powder 21 of the petroleum coke 1 in a fine powder state.

In addition, in the first and second specific examples described above, the high-concentration coal slurry 1 is obtained by dehydrating the low-concentration slurry produced by the pulverizers 9 and 22 as the coal pulverizing system with the dehydrator 14.
The method for obtaining 8 is described above.
Alternatively, the additive may be supplied together with water 10 to perform high-concentration pulverization to directly obtain a high-concentration slurry.

The crusher for coal 7 may be a combination of a primary crusher and a secondary crusher as appropriate.

When the mixing ratio of the petroleum coke 1 is high, a part of the petroleum coke 1 is directly supplied to the coal pulverizer 22 together with the coal 7 and pulverized to adjust the amount of ultrafine powder of the petroleum coke 1. . Further, the crushing system for the petroleum coke 1 can be freely selected, and in addition to this, the type of the crusher for the coal 7 and the petroleum coke 1, the mixing ratio of the petroleum coke 1, the type of the additive 17 Or addition position,
The presence or absence of a deashing process is also free.

Further, a storage tank may be provided at an appropriate place during the manufacturing process.

(Effect of the Invention) According to the present invention, when preparing a coal slurry composed of crushed coal and petroleum coke, and water,
Since the coal and petroleum coke were crushed so that the particle size of petroleum coke was smaller than the particle size of coal, the proportion of pulverized coal in the ultrafine powder of the coal slurry was reduced, and the amount of petroleum coke that was easy to grind was reduced by that amount. Can be supplemented in the form of fine powder. Therefore, in preparing the coal slurry, the required power for pulverization is reduced as compared with the conventional one, and at the same time, the abrasion of the components of the pulverization device is also reduced.

Moreover, the petroleum coke mixed in the coal slurry is finely pulverized when the coal slurry is burned, so that the combustibility is remarkably improved. That is, in the early stage of the combustion of the coal slurry, the pulverized coal mixed therein is burned to raise the atmospheric gas temperature, which facilitates the ignition of the petroleum coke, and once the combustion is started, as described above. Since petroleum coke is pulverized, the burnout time is short. Further, upon combustion, the calorific value of petroleum coke is higher than that of coal and the ash content is less, so that the calorific value of the coal slurry can be increased and the ash content can be reduced according to the mixing ratio of the petroleum coke.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a process drawing showing the first embodiment, and FIG. 2 is a process drawing showing the second embodiment. 1 ... Petroleum coke, 2 ... Preliminary crusher, 7 ... Coal,
9 ... Crusher, 10 ... Water, 17 ... Additive, 18 ...
Coal slurry, 20 ... Crusher, 22 ... Crusher.

Claims (4)

[Claims] 1. When preparing a slurry of coal consisting of crushed coal, petroleum coke which is delayed coke, and water, the coal and petroleum coke are crushed so that the particle size of petroleum coke becomes smaller than the particle size of coal. A method for preparing a coal slurry, comprising: 2. The method for preparing a coal slurry according to claim 1, wherein petroleum coke is pre-ground and the pre-ground petroleum coke and coal are ground together. 3. The method for preparing a coal slurry according to claim 1, wherein coal and petroleum coke are separately crushed, and then the crushed both are mixed with each other. 4. Preparation of coal slurry according to any one of claims 1 to 3, characterized in that the crushing of coal is carried out by a wet method while the grinding of petroleum coke is carried out by a dry method. Method.