JPH0160198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coal deashing device for removing ash from coal.

In recent years, the use of coal as a fuel to replace oil has been reconsidered. The disadvantage of coal is its lack of fluidity, which is the inconvenience of transporting, storing, and handling of solid coal compared to liquid petroleum. Various measures are being considered to deal with the problem of handling the ash content.

For example, to solve the problem of fluidity, techniques have been developed in which coal is liquefied or gasified, or it is made into a fine powder and then made into a water-based or oil-based slurry.

On the other hand, as the latter ash removal method, that is, deashing method, foam flotation method, wet granulation method, etc. are known. However, each method has various drawbacks, and cannot be said to be a fully satisfactory method for deashing particularly fine-grained pulverized coal.

The ash content of coal can be divided into the following three types based on its origin. In other words, (1) inorganic content contained in the composition of plants that were converted into coal (usually said to be less than 1%); (2) inorganic content contained in groundwater due to infiltration of groundwater into the coal seam; Minutes entered the coal seam and precipitated.

(3) Mineral substances that invaded from the outside during the process of coalification.

Of the above, the main ones quantitatively are (2) and (3).
The ash content is

These ash contents can be easily observed with a microscope, but
It exists in coal in sizes ranging from a few microns to several tens of microns, and it is theoretically believed that if the coal is crushed very finely, the coal and ash can be separated and the ash can be removed. .

The ash content to be removed by foam flotation, wet granulation, etc. also belongs to (2) and (3).

However, these currently developed deashing methods each have the following drawbacks, and the ash removal rate is also extremely low.

That is, the foam flotation method mainly uses particles with a particle size of 0.5
This method is used for sorting and removing ash from pulverized coal of mm or less. However, the target pulverized coal is 74
In the case of fine particles such as microns (200 mesh) or less, it is difficult to perform the purpose of separating pulverized coal and removing ash content sufficiently, and there are disadvantages such as a decrease in the recovery rate of coal content.

On the other hand, wet granulation is a method that takes advantage of the fact that coal is lipophilic and ash is non-lipophilic.

That is, by treating pulverized coal with a mixture of oil and water, only the coal components are aggregated through the oil, and then granulated by rolling in the liquid. This granulated material is separated from the aqueous phase to which the ash has migrated using a screen.

Therefore, coal deashing equipment that belongs to the wet granulation method must be equipped with a powerful stirring tank that aggregates and granulates coal, oil, and water, and a screen that separates the granules from the water phase. It is characterized by These deashing devices can process pulverized coal down to several microns, and the coal recovery rate is high at 95-98%.
reach.

However, it is difficult to say that it is a satisfactory coal ash removal device for the following reasons.

(1) When coal is pulverized from several microns to several tens of microns (ultra-finely pulverized state), the surface area of the coal increases. In order to granulate pulverized coal consisting of such fine particles to a size that allows separation by a screen, it is necessary to add a large amount of oil.

For 100 parts by weight of coal, 15 to 30 parts by weight of oil is required.

(2) Granulation from ultrafine powder requires a large amount of energy. The power required for the stirring tank is large and the stirring time is long.

(3) Because the diameter of the granules is large, it is difficult to remove the ash mixed in during agglomeration and granulation by washing the granules with water. Therefore, the ash removal rate decreases.

Improvements have been made to the wet granulation method as described above, but all of these methods produce aggregates (granules).
This method is based on separation using a screen, and while it is complicated to operate, it is not sufficiently effective.

The present invention is similar to conventional deashing means using a wet granulation method in that fine coal powder, oil, and water are placed in a stirring tank and treated to produce an aggregate of coal and oil.

However, in the present invention, in addition to the above, since the necessary amount of air is introduced, fine air bubbles are captured in the produced aggregates, and the aggregates have floating properties, and when left standing, coal and oil aggregates form. collects in the upper layer, and the aqueous phase suspended with ash becomes the lower layer and separates into layers. Therefore, it is possible to collect only the coal from the upper layer of the stationary tank without using a screen.

According to the present invention, it is not necessary to increase the size of the agglomerates to the extent necessary for the separation operation using a screen, so the amount of oil used is 4 to 4 parts by weight per 100 parts by weight of coal.
It only requires 6 parts by weight, does not require a powerful stirrer, and the stirring time depends on the type of coal, but it only takes about a few minutes, and the energy required for stirring is small.

Furthermore, the bond between the aggregate and the microbubbles is strong, and the aggregate does not lose its floating ability even if the aggregate is placed in a water tank and stirred several times.

Therefore, most of the ash mixed inside the aggregate can be removed, resulting in a high ash removal rate. The coal recovery rate is also over 95%, reaching the same level as coal deashing equipment using the conventional wet granulation method.

Due to these effects, the present invention improves all of the drawbacks (1) to (3) mentioned above as problems of the coal deashing apparatus using the wet granulation method.

Next, one embodiment for carrying out the present invention will be described in detail with reference to the drawings.

In FIG. 1, numeral 1 is a coal slurry storage tank filled with coal slurry that has been pulverized to about 50 microns or less and prepared by adding water to pulverized coal.

A stirring device 1 is inserted through the top of the coal slurry storage tank 1 to prevent the coal slurry from settling at the bottom of the storage tank 1.
It is constantly stirred by a.

1b is a plurality of baffle plates attached to the inner peripheral wall of the storage tank. This baffle plate 1b appropriately suppresses rotation of the coal slurry as the stirring device 1a is operated.

4 is an emulsification tank for mixing and stirring oil, water, and additives to prepare emulsified oil. 4a is a stirring device, 4b
is a baffle board. 7 is an air compressor.

The coal slurry in the coal slurry storage tank 1 is pumped through the pump 2.
The water is supplied through a pipe 3 to an agitator 9 having a structure as described below.

On the other hand, the emulsified oil in the flotation tank 4 is injected into the pipe 3 through the pipe 6 by the pump 5 and merges with the coal slurry. Further, compressed air generated by the operation of the air compressor 7 is similarly injected into the pipe 3 through the pipe 8.

The coal slurry, emulsified oil, and compressed air in the pipe 3 are fed into one end of the agitator 9 while being mixed with each other.

The stirrer 9 is constructed as shown in FIG.

That is, the stirrer 9 is of a horizontal cylindrical type, and is formed into a cylindrical body by connecting a plurality of cylindrical tubes 32 in series through flanges, and each adjacent cylindrical tube 32
A partition plate 33 is sandwiched between the flanges. The partition plate 33 is constituted by a donut-shaped disk having an outer diameter larger than the cylindrical tube 32 and an inner diameter slightly larger than the diameter of the shaft 34 passing through the center line of the stirrer 9. Therefore, shaft 34
There is an annular gap 33 between the inner diameter of the partition plate 33 and the inner diameter of the partition plate 33.
a is formed.

Further, blades 37 are provided radially on the shaft 34 via a boss 36, and these blades 3
7, each single tube 32 is provided with a plurality of baffle plates 38 arranged radially on its inner peripheral surface.

39 is a slurry inlet, 40 is a slurry outlet 41
is a viewing window.

In the stirrer 9, the coal in the coal slurry forms aggregates using oil as a binder, and at the same time, fine air bubbles are trapped in the aggregates.

Here, the stirrer 9 is connected to the partition plate 3 for each cylindrical pipe 32.
3, the gap 33a between the partition plate 33 and the shaft 34 is small, so during the stirring operation in each cylindrical tube (the blades 37 are rotated in the coal slurry by the rotation of the shaft 34), the coal is The movement of the slurry in the axial direction is suppressed, resulting in a very good stirring effect, which is further enhanced by the fact that a plurality of partitioned cylindrical tubes are arranged in series. Therefore, many ash-free coal aggregates can be formed in a short time.

When stronger stirring is continued by the blades 37, the aggregates are granulated into spherical shapes and gradually grow, similar to the conventional deashing apparatus.

The slurry in which coal agglomerates have been formed in this manner is sequentially discharged from the slurry outlet 40 through the gap 33a between the partition plate 33 and the shaft 34.

This movement of the slurry is effected by the pressure of the pumps 2, 5 and the air compressor 7.

Coal agglomerates that trap fine air bubbles have the ability to float horizontally.

The present invention utilizes this floating property to advantageously perform deashing.

The slurry containing coal aggregates leaving the agitator 9 is
It is sent to a separation cleaning tank 11 through a pipe 10.

As shown in FIGS. 3 and 4, the separation and cleaning tank 11 is composed of an agitation tank 11a and a static tank 11b, and a shaft 42 is arranged horizontally and rotatably in the agitation tank 11a. There is.

The shaft 42 has a plurality of blades 43 arranged radially.
are provided protrudingly, and a baffle plate 44 is provided protrudingly from the inner wall of the stirring tank opposite to these blades 43.
These members constitute a stirring device 11c.

The stationary tank 11b adjacent to the stirring tank 11a is formed into a pyramid shape that narrows downward, and a viewing window 45 is provided on the side surface.

A discharge port 46 for overflowing slurry is provided at the upper part of the stationary tank 11b.

The slurry containing coal aggregates sent to the stirring tank 11a is stirred and washed while being diluted by water sent from a water distribution system via a pipe 12, which will be described later.

The stirring action is performed by a stirring device 11c. Ash is separated from the slurry containing coal aggregates by this stirring and washing action.

As a result, a slurry containing coal aggregates with a low ash content is obtained.

The slurry in this state is removed from the partition plate 11.
d and overflows into the stationary tank 11b side.

In this stationary tank 11b, the slurry containing microbubbles and a coal agglomeration rate with a low ash content and buoyancy collects in the upper layer of the tank, and the lower layer is a suspended layer of ash and water. Become.

By the way, as shown in FIG.
If you install two or more stages in a row,
By further adding the above-described stirring and separation effects, it is possible to more effectively obtain a slurry containing coal aggregates with a low ash content.

The slurry discharged from the stationary tank 11b enters the dehydrator 14 via the pipe 13, where it is dehydrated to become deashed coal and taken out from the dehydrator 14.

On the other hand, the mixed suspension of ash and water forming the lower layer in the static tanks 11b and 11b' is extracted by the pump 30 and guided to the pipes 15 and 16.
Further, the water separated by the dehydrator 14 is led to a pipe 17, extracted by a pump 30, and led to a pipe 29, and both are sent to wastewater treatment equipment.

Wastewater treatment equipment includes 18 flocculant adjustment tanks and 1 pump.
9, Piping 20, Stirring tank 21, Piping 22, Sedimentation tank 2
3. It is mainly composed of a pump 24, piping 25, and a dehydrator 26.

The flocculant adjustment tank 18 is for dissolving and adjusting in water a flocculant used to coagulate and precipitate ash in waste water. 18a is a stirring device, 18b
are baffle plates, and both have the same configuration, function, and effect as those installed in the coal slurry storage tank 1 or the flotation tank 4.

The flocculant adjusted in the flocculant adjustment tank 18 passes through the pipe 20 by the pump 19, joins with the aforementioned suspension of ash and water, and enters the stirring tank 21.
Here it is mixed and stirred. 21a is a stirring device.

The waste water containing the flocculant and ash is further guided to the pipe 22 and enters the settling tank 23.

In the sedimentation tank 23, the ash in the waste water is coagulated and settled by the effect of the flocculant, and the overflow water becomes clear.

The ash accumulated at the bottom of the settling tank 23 is removed by a pump 24.
It is extracted by
It is dehydrated and becomes ash sludge. The water separated by the dehydrator 26 is returned to the stirring tank 21 through a pipe 27 by a pump 31 and is circulated.

Also, overflow water from the sedimentation tank 23 is passed through the pipe 12 by a pump 28 to the separation cleaning tanks 11 and 11'.
The water is returned to the stirring tanks 11a and 11a' and used as dilution washing water.

Since the present invention performs a coal deashing method using the above-described configuration, the following effects can be achieved.

As explained above, according to the coal deashing apparatus according to the present invention, the inside of the cylindrical pipe is divided into small chambers and small gaps communicating between the small chambers are provided so as to mix and stir the floating oil into the coal water slurry. Since it is formed between the stirring blade and the shaft attached to the stirring blade, a large amount of slurry agitation and atomization can be performed with small power due to the closed chamber effect. Moreover, due to the throttling action when passing through the small gap and the expansion action accompanying the transition to the small chamber,
A higher atomization effect can be obtained, and a high floating effect can be obtained by turning the entrained air into fine bubbles and trapping them in coal aggregates in the subsequent process.

[Brief explanation of drawings]

Fig. 1 is a coal deashing treatment system diagram of the present invention, Fig. 2 is a longitudinal sectional side view of the stirrer, Fig. 3 is a plan view of the separation and cleaning tank, and Fig. 4 is a sectional view taken along the line A-A in Fig. 3. . 1 is a coal slurry storage tank, 1a is a stirring device, 1b is a baffle plate, 2, 5, 19, 24, 28, 30, 31
is the pump, 3, 6, 8, 10, 12, 13, 1
5, 16, 17, 20, 22, 25, 27, 29
is piping, 4 is a flotation tank, 7 is an air compressor, 9 is an agitator, 11, 11' is a separation cleaning tank, 11a, 11
a' is a stirring tank, 11b, 11b' is a static tank, 11c,
11c' is a stirring device, 11d is a partition plate, 14,2
6 is a dehydrator, 18 is a flocculant adjustment tank, 21 is a stirring tank, 23 is a sedimentation tank, 32 is a cylindrical pipe of the stirrer 9, 3
3 is a partition plate, 34 is a shaft, 35 is a bearing, 36 is a boss, 37 is a blade, 38 is a baffle plate, 3
9 is a slurry inlet, 40 is a slurry outlet, 42 is a shaft of the stirring tank 11a, 43 is a blade, and 46 is a slurry outlet.

Claims (1)

[Claims] 1 Mix oil and air into a mixed slurry of coal and water, stir it, add water to the slurry containing coal aggregates, stir and wash it, and separate it into a coal layer and an ash layer. The agitator for the coal-water slurry used in a coal dewatering device that concentrates and dehydrates a coal aggregate slurry produced by separation and washing and from which ash has been removed, wherein the agitator is of a horizontal cylindrical type. A coal removal device characterized in that a partition plate is provided, which passes through a shaft having a large number of stirring blades attached to the center thereof, divides a cylindrical pipe into small chambers, and forms a small gap between the shaft and the shaft. Ash equipment.