JPH05230480A - Material and method for preventing spontaneous ignition and dusting of coal pile, and structure of coal pile - Google Patents

Abstract

PURPOSE:To obtain the title material capable of preventing the spontaneous ignition and dusting of, e.g. coal piled up at a thermal power plant, an iron mill, a mine, etc., by using a specified resin as the effective constituent. CONSTITUTION:A highly water-absorptive synthetic resin (e.g. Sanwet IM5000, a product of Sanyo Chemical Industries) is used as the effective constituent for the title material. Preferably, a layer of a mixture of a highly water- absorptive synthetic resin and coal is formed on the surface of a coal pile in such a manner that the mixture layer contains water, thus preventing the spontaneous ignition and dusting of the coal pile.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a thermal power plant, a steel mill,
The present invention relates to a spontaneous ignition / dust-preventing agent for accumulated coal or the like (hereinafter abbreviated as “coal pile”) in a mine or the like.

[0002]

2. Description of the Related Art In a thermal power plant or the like, coal used as fuel or the like is unloaded by a ship, accumulated in an outdoor stockyard to a height of about several tens of meters and stored, and if necessary, the coal pile is demolished. It is transferred to a plant such as a boiler for use.

However, when coal is left outdoors for a long time while being deposited, carbon or sulfur in the coal is gradually oxidized by oxygen in the air. Since the oxidation reaction is an exothermic reaction, thermal energy is generated and also receives solar heat to accumulate thermal energy. Since the amount of thermal energy stored in the coal pile increases over time,
Especially in summer, there is a risk of reaching a critical point and spontaneously igniting.

The spontaneous ignition of such a coal pile brings about social unrest, and when spontaneous ignition occurs, it must be extinguished, and the following disadvantages occur during extinction.

Since the coal that has disappeared cannot be used, it causes enormous property damage.

[0006] Fire extinguishing activities require manpower and equipment, and personnel costs and the like cause cost increase.

Sulfuric acid and sulfurous acid in which sulfur content in coal is oxidized are dissolved in water used for fire extinguishing to form sulfate ions, so that the pH of the wastewater rises sharply and is not neutralized in the wastewater treatment process. Don't

When coal is deposited in a stockyard, it is necessary to prevent dust from scattering in order to prevent environmental pollution due to scattering of coal powder.

As a method for preventing spontaneous ignition and scattering of coal powder, a method of spraying a high molecular weight aqueous solution of vinyl acetate polymer, latex or the like on the surface of coal pile and drying it to form a film (JP-A-52) No. 51401, Japanese Patent Laid-Open No. 51-
No. 1337701) is known.

As a method for preventing dust generation, installation of a water sprinkling facility or installation of a wind shield net is generally carried out.

[0011]

Of the above-mentioned conventional techniques,
In the method of preventing spontaneous ignition using a polymer aqueous solution, if there is rainfall before the polymer aqueous solution dries, rainwater causes the polymer aqueous solution to flow out, and it is necessary to spray the polymer aqueous solution again, which increases the cost. To do. Further, if the aqueous polymer solution flows out into the drainage, the drainage pipe may be clogged and the drainage treatment may be inconvenient.

The method of preventing dust generation by installing a sprinkling facility or a wind-shielding net is effective for preventing the scattering of coal powder. However, in the method using a sprinkler, it is necessary to always manage the water content on the coal surface, and since dust flows out into the wastewater discharged from the stockyard, it must be removed by agglomeration, precipitation, etc. However, the method of installing the wind-shielding net has the drawback of enormous equipment cost.

The object of the present invention is to spontaneously ignite coal piles.
(EN) It is intended to provide a dust-preventing agent, a method for preventing spontaneous ignition / dust generation of a coal pile, and a coal pile structure in which spontaneous ignition / dust is prevented.

In addition to the above, if the rainwater is not allowed to penetrate into the coal bed, there is a problem that the fuel efficiency is increased by the amount of drying excess water and the boiler efficiency is reduced. The purpose is also to solve.

[0015]

The present invention has been made in order to solve the above-mentioned problems, and the first invention is the following agent for preventing spontaneous ignition and dust generation of coal piles. ..

That is, the self-igniting / dust-preventing agent for coal piles of the present invention is characterized by containing a highly water-absorbent synthetic resin as an active ingredient.

The highly water-absorbent synthetic resin used in the present invention is capable of absorbing several tens to 1,000 times or more its own weight of water.
It refers to a polymer that swells in water to form a hydrogel, and the structure is not particularly limited as long as it is a polymer that exhibits this function, and examples thereof include the following polymers.

Starch-based: Starch-based graft-polymerized with polyacrylonitrile or the like. Cellulose type: Cellulose obtained by graft-polymerizing polyacrylonitrile or acrylic acid onto cellulose, or carboxymethyl cellulose crosslinked with epichlorohydrin.

Polyvinyl alcohol type: Polyvinyl alcohol cross-linked with cyclic acid anhydride, or saponified copolymer of acrylic and vinyl acetate.

Acrylics: Saponified products of crosslinked polyacrylates and polyacrylonitonyl polymers.

Cross-linked polyethylene oxide type: A cross-linked product of polyethylene oxide such as polyethylene glycol diacrylate.

The shape of the superabsorbent synthetic resin in the present invention is not particularly limited as long as it can be sufficiently mixed with coal.
A powdery or fibrous form is preferred.

The second and third inventions of the present invention are as follows.
A method for preventing spontaneous ignition and dust generation of a coal pile, which comprises forming a mixed layer of the superabsorbent synthetic resin and coal as a surface layer of the coal pile, and including water in the mixed layer, and the surface of the coal pile. The present invention relates to a coal pile structure in which a hydrogel layer containing a mixture of water-containing superabsorbent synthetic resin and coal is covered.

In order to form the mixed layer in the second invention, 0.01 to 10% by weight of the superabsorbent synthetic resin may be mixed with coal. If the amount is less than 0.01% by weight, the formation of the hydrogel layer is insufficient and no effect is obtained. Even if the amount of the highly water-absorbent synthetic resin is more than 10% by weight, the effect cannot be expected to increase, and the cost also increases, which is not preferable ..

The coal to be treated in the present invention includes domestic coal,
The thickness of the mixed layer regardless of the type of coal such as the coal producing area such as overseas coal and lignite, sub-bituminous coal, bituminous coal, anthracite, etc. varies depending on the size of the coal pile, but is preferably in the range of 0.1 to 5 m. The method for forming the mixed layer is not particularly limited,
For example, on a transfer means such as a belt conveyor that transfers coal to the stockyard, the superabsorbent synthetic resin is sprayed by an automatic feeder, and the superabsorbent synthetic resin and coal are sufficiently mixed during transfer to form a mixed layer. Examples include a method and a method in which coal and superabsorbent synthetic resin are mixed in advance in another plant and the mixture of the coal and superabsorbent synthetic resin is loaded on the surface of the coal pile.

In this way, the highly water-absorbent synthetic resin mixed with coal swells due to water in the coal or water sprinkling,
A hydrogel layer is formed on the surface of the coal pile. And the formation of this hydrogel layer prevents the scattering of coal powder,
In addition, since air is blocked, the oxidation reaction of carbon and sulfur in coal is suppressed, and spontaneous combustion is prevented.

[0027]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to the following examples.

Examples 1 to 7 and Comparative Examples 1 to 4 As shown in FIG. 1, coal is put into a column whose filter bed plate 5 is 100 mesh Saran, and the bottom is 100 cm and the height is 75 c.
m, width 65 cm, angle of repose 37 degrees for test coal pile 2
Formed. Next, on the surface layer of the coal pile for this test, a starch-based highly water-absorbent synthetic resin (manufactured by Sanyo Chemical Industry Co., Ltd., trade name "Sunwet IM500" in the proportions shown in Table 1 was used.
0 ") is blended to form a layer which is well mixed with coal to about 1 cm.
Water is formed by the water sprinkling equipment 3 and then 100 to 30
Water was sprayed with 0 ml to form a hydrogel layer.

After air-drying for one day, a blower test was conducted for 5 minutes by the blower 6 at a wind speed of 15 m / s, and the scattering rate and the sprinkled water were collected in the water collecting tank 4 to measure the SS concentration in the water.
The measurement results are shown in Table 1. The scattering rate was calculated according to the following formula.

[0030]

[Equation 1]

[0031]

[Table 1]

As is clear from the results shown in Table 1, the scattering rate of coal powder was reduced, and the effect of preventing the scattering of coal powder was recognized.
Further, it is confirmed that the SS in the collected water of the sprinkling water is small and the outflow of dust is prevented.

Example 8, Comparative Example 5 About 700 tons of coal was deposited at a repose angle of about 37 degrees and a height of about 10 m to form a coal pile, and a thermometer was installed at a position about 2 m deep from the top. did.

Acrylic superabsorbent synthetic resin (manufactured by Toa Gosei Kagaku Kogyo Co., Ltd., trade name "Aron Zap RS-
2 ") is added to the coal in an amount of about 0.1% by weight, mixed well, and then loaded on the surface of the coal pile to form a mixed layer of 30 cm.
Formed. About 8,000 liters of water was uniformly sprayed on the surface of the coal pile to form a hydrogel layer. Table 2 shows the results of measuring the change with time of temperature. As a comparative example, Table 2 also shows the results of similarly measuring the internal temperature of the coal pile to which the superabsorbent synthetic resin was not added.

[0035]

[Table 2]

As is clear from the results shown in Table 2, it is understood that the present invention suppresses the temperature rise inside the coal pile and prevents spontaneous ignition.

Examples 9 to 16 and Comparative Example 6 Coal was put in a column as shown in FIG.
A test coal pile 2 having m, height of 75 cm, and angle of repose of about 37 degrees was prepared. On the surface layer of the test coal pile 2, the acrylic acid-based highly water-absorbent synthetic resin (manufactured by Toagosei Kagaku Kogyo Co., Ltd., trade name "Aronzap RS-2") was used in the proportions shown in Table 3.
Was blended to form a well mixed layer with coal. Next, about 200 ml of water was sprinkled to form the hydrogel layer 1.

After about 1 hour, 4 mm of water equivalent to 50 mm / day was added.
Watered in time. After the watering was completed, the water content at each point A, B and C in FIG. 2 was measured. The results are shown in Table 3.

A is the bottom of the pile 2 and is 10 cm from the wall, and B is the bottom of the pile 2 and is 6 cm from the wall.
The position C is 5 cm, and the position C is 35 cm above the bottom surface of the pile 2 and 50 cm above the wall.

[0040]

[Table 3]

As is clear from the results shown in Table 3, according to the present invention, the water content of the coal does not change even when water is sprinkled, and therefore the dry fuel consumption can be reduced.

[0042]

According to the present invention, the following effects can be obtained by forming a hydrogel layer of a super absorbent synthetic resin and water on the surface of a coal pile.

Since the hydrogel layer blocks the contact between oxygen in the air and the coal, the oxidation reaction of the coal is suppressed and spontaneous combustion is prevented.

Since the entire surface of the coal pile is covered with the hydrogel layer, dust generation of coal powder is prevented.

The hydrogel layer prevents rainwater from penetrating, so that the water content of the coal does not become excessive and the dry fuel consumption can be reduced.

Since the superabsorbent synthetic resin does not easily dissolve in water once it is hydrogelized, it does not flow out even if it is rained and does not adversely affect the wastewater treatment facility.

The superabsorbent synthetic resin used in the present invention is
It is composed of elements such as C, H, O, Na, K, N,
Since it does not contain heavy metals, chlorine, etc., it does not adversely affect the boiler body even when the coal containing the hydrogel layer of the present invention is burned.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a test apparatus in Examples 1 to 7.

FIG. 2 is a diagram showing an outline of a test apparatus in Examples 9 to 16.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hydrogel layer 2 ... Coal pile (coal layer) 3 ... Sprinkler equipment 4 ... Water collection tank 5 ... Filter floor plate 6 ... Blower

Claims (3)

[Claims] 1. A self-igniting / dust-preventing agent for coal piles, which comprises a highly water-absorbent synthetic resin as an active ingredient. 2. A method for preventing spontaneous ignition and dust generation of a coal pile, which comprises forming a mixed layer of a super absorbent synthetic resin and coal as a surface layer of the coal pile and including water in the mixed layer. 3. A coal pile structure, characterized in that the surface of the coal pile is covered with a hydrogel layer containing a mixture of a superabsorbent synthetic resin containing water and coal.