JPH0318677B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing a mixed fuel of coal and heavy oil, which produces a mixed fuel of coal and heavy oil while separating ash from pulverized coal, and particularly relates to a method for producing a mixed fuel of coal and heavy oil. A method for producing a coal/heavy oil mixed fuel in which a slurry of pulverized coal and water is formed, and heavy oil and air are supplied to the slurry to concentrate the coal in the oil phase and the ash in the water phase. Regarding.

The ash content ratio in coal varies depending on the type of coal, and even within the same type of coal, the distribution of ash content differs. However, in any type of coal, the charcoal and ash are liberated by pulverizing the coal, so charcoal from this liberated ash and charcoal mixture is selectively attached to oil droplets to remove the ash in the coal. It is being liberated.

Conventionally, as a method for deashing such coal, a method has been proposed in which oil is added to a pulverized coal/water slurry phase and mixed and stirred at high speed, thereby concentrating the coal content into an oil phase. However, this method has the drawback that during the process of coagulation of coal into the oil phase, the coal aggregates incorporate ash from the aqueous phase, resulting in a low deashing rate, and the amount of coal processed is insufficient for the amount of oil used. It was hot.

An object of the present invention is to provide a method for directly producing a mixed fuel of coal and heavy oil that can be used as fuel for a coal-fired boiler while removing ash from pulverized coal.

When producing a coal/heavy oil mixed fuel, the present inventors introduced oil from the lower side of the deashing tower into which the coal/water slurry was first introduced as a method to improve the deashing rate of coal. An application has been filed for a method for causing coal content to adhere to the formed oil film and float it to the surface. This invention improves the coal ash ratio, but when the oil is heavy oil, which has a specific gravity close to that of water, the floating speed is slow, causing problems in large-scale processing of coal.

In the present invention, heavy oil and air are introduced from the lower side of a slurry of crushed coal and water (deashing tower), and the ash content in the coal is attached to the oil droplets or oil film that is formed to form an oil phase. By concentrating the coal content in the water phase and the ash content in the water phase, the intended specific gravity of the heavy oil with a high specific gravity that floats in the retention section (deashing tower) is reduced, and the floating force of the heavy oil is improved. The above objective is achieved by floating a mixture of coal and heavy oil on the top of the deashing tower.

First, the principle of the present invention will be explained with reference to FIG. Coal 100 is supplied to a crusher 1 and pulverized, and then supplied to a mixing tank 2 through a line 101. In mixing tank 2, the water from lines 115, 116 and 117 is mixed with the pulverized coal to form a slurry of coal and water. The coal/water slurry is led to a separator (deashing tower) 3 through a line 102, and is supplied from the middle section of the deashing tower 3. On the other hand, heavy oil passes from the oil tank 8 through line 121 and is pressurized by pump 9, and from line 112 to line 110 to line 11.
1, and merges with a line 103 that supplies air pressurized by the pump 11 from a line 104, and is supplied to the lower part of the deashing tower 3 from a line 105 in a two-fluid state of heavy oil and air.

In the deashing tower 3, the coal concentrated into heavy oil is transferred to line 10.
The air extracted from the deashing tower 3 and supplied to the deashing tower 3 rises inside the deashing tower 3 and passes through the line 12 at the top of the deashing tower 3.
Extracted from 3. On the other hand, the ash concentrated in the aqueous phase is led to the sedimentation tank 7 from the line 118, the settled ash is extracted from the line 122, and the supernatant liquid passes through the line 119, flows from the pump 10 through the line 114, and joins the line 113. The water then reaches line 115 and becomes make-up water for the coal/water mixing tank. The coal extracted from the upper part of the deashing tower 3 and concentrated into heavy oil is led to the decanter 4 through a line 106. In the decanter 4, oil and charcoal are separated by sedimentation. A mixture of coal and heavy oil is extracted from line 107 and supplied to water washing tower 5.

In the water washing tower 5, heavy oil and ash adhering to the coal are washed with water from line 116, and the ash is extracted into an aqueous phase.The aqueous phase is extracted from line 113 and sent to a settling tank from line 114. It merges with the supernatant liquid from No. 7 and becomes make-up water for the coal/water mixing tank. Heavy oil and charcoal are extracted from line 108, then sent to oil adjustment tank 6, the amount ratio of heavy oil and charcoal is adjusted by the amount of oil supplied from line 111, and then extracted from line 109. , used as a mixed fuel of coal and heavy oil.

In this embodiment, the heavy oil supplied from the oil tank 8 to the deashing tower 3 has a high deashing rate and is effective. If we consider the case where low boiling point oil such as kerosene or gasoline is used as the oil, an oil recovery process is required to treat the mixture of coal and oil extracted from the water washing tower, so it is not possible to directly use the coal/heavy oil mixed fuel. cannot be manufactured. Therefore, the cost becomes high.

The heavy oil used in the present invention has a specific gravity of 0.9 to 1, which is almost the same as that of water. Therefore, if heavy oil is simply placed in water, it will not disperse as it is, but will aggregate into lumps, resulting in a low deashing rate and Recovery rate is low.
Furthermore, when heavy oil adsorbs coal, the heavy oil does not float to the surface but settles in the water, making it impossible to deash or recover the coal.

Since the present invention blows heavy oil and air, the non-hydrophilic heavy oil adheres around the bubbles, and the apparent specific gravity becomes less than 1, forming oil droplets that float in the water.

Hereinafter, the effects of the present invention will be clarified through Examples.

FIG. 2 shows the test results of the conventional mixing and stirring method, a comparative example, and the present invention.

First, in the conventional mixing and stirring method, Blairsall Charcoal A,
About Warkworth Coal B and Ermelo Coal C, 250
It was crushed into pieces smaller than mesh. The average ash content at this time was 8.2% for Blairsall coal, 12.9% for Warkworth coal, and 14.1% for Ermelo coal. Each type of coal was mixed with water to create a slurry with a coal concentration of 10%. Approximately 25% B heavy oil was added to the amount of coal in this slurry, and the coal/water slurry and heavy oil were mixed and stirred for 2 hours using a high-speed impeller rotating at approximately 1200 rpm to remove the ash of the coal that had coagulated in the oil phase. The deashing rate was calculated based on the ratio to the ash content in the charged coal. As a result, the deashing rates of Blairsall coal A, Warkworth coal B, and Ermelo coal C were 27%, 27%, and 30%, respectively.

On the other hand, as a comparative example, a coal/water slurry with a coal concentration of 10% was prepared by pulverizing Ermelo coal to 250 mesh or less, and the slurry was floated and deashed using kerosene D and heavy oil E as oils. Furthermore, as an example of the present invention, a test was conducted in which heavy oil and air were simultaneously supplied to a coal/water slurry (in Fig. 2,
) was carried out. For comparison, a test (indicated by G in FIG. 2) was conducted in which kerosene and air were simultaneously supplied to a coal-water slurry.

The test device was a glass tube with an inner diameter of 27 mmφ and a height of 500 mm, in which the coal/water slurry described above was placed, and oil and air were supplied from the bottom. The amount of oil supplied is
5.6/mm·m ² , and the oil droplet diameter was 2 to 5 mmφ.
At that time, the ash content of the coal concentrated in the oil phase was determined and the deashing rate was expressed as a ratio to the ash content of the charged coal.

In the results of D, in which kerosene was used as the oil, the deashing rate was 49%, whereas in the results of E, in which heavy oil B was used as the oil, the deashing rate was 33%. In addition, air 50/mm・
In the deashing method according to the present invention, which simultaneously supplies two liquids, m ² and heavy oil 5.6/mm・m ² , and floats by forming a heavy oil film on the floating air, the deashing rate is as shown in the result of F. This has improved to 53%. For comparison, when kerosene and air were supplied in the same manner, the deashing rate was 58% compared to when heavy oil was used. However, in this case, in order to use coal as fuel for the boiler, a step is required to separate the coal and kerosene.

As described above, according to the present invention, heavy oil and air are supplied from below to the coal/water slurry in the deashing tower,
The apparent specific gravity of heavy oil with high specific gravity is reduced by air, improving the levitation force of the oil droplets with coal content, concentrating the coal content in the floating heavy oil, and producing a coal/heavy oil mixed fuel. Since it is manufactured, the following effects are achieved.

(1) The deashing rate can be significantly improved compared to when only heavy oil is supplied to the coal/water slurry, and the efficiency of producing coal/heavy oil mixed fuel can be improved.

(2) The power required for stirring in the conventional mixing and stirring deashing method can be eliminated, reducing power costs.

(3) It eliminates the need for gas separation and recovery, which is required when deashing using kerosene, gasoline, etc., which simplifies the manufacturing process, and eliminates the need to remove kerosene, etc. adhering to coal, resulting in a coal/heavy oil mixed fuel. can be manufactured directly.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an example of the present invention, and FIG. 2 is a diagram showing deashing rates in a conventional example, a comparative example, and an example of the present invention. 1...Crusher, 2...Mixing tank, 3...Deashing tower,
4... Decanter, 5... Water washing tower, 6... Oil adjustment tank, 7... Sedimentation tank, 8... Oil tank, 9, 10,
11...pump, 100...coal.

Claims (1)

[Claims] 1. A slurry of pulverized coal and water is supplied to a deashing tower, heavy oil and air are supplied from the bottom of the deashing tower, and the air bubbles that are formed are accompanied by oil droplets to float naturally in the slurry, and the coal is removed. While concentrating the ash into the aqueous phase,
A method for producing a coal/heavy oil mixed fuel, which is characterized by causing a mixture of coal and heavy oil to float to the top of a deashing tower by attaching charcoal content to oil droplets.