JP2004035783A - Heat generation / ignition prevention agent and its prevention method - Google Patents

Abstract

Heat and ignition of carbonaceous mass powder capable of sufficiently suppressing heat generation and ignition during stacking storage of carbonaceous mass powder such as coal and carbon black, particularly during stacking storage of silos and the like. To provide a preventive agent and a method for preventing the same.
The heat generation / ignition inhibitor of the present invention is characterized by comprising an aqueous alginic acid solution. The heat generation / ignition prevention method for preventing ignition and heat generation according to the present invention comprises the steps of: A gel coating is formed on the stacked carbonaceous mass powder using a curing agent for gelling.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an agent for preventing heat generation and ignition and a method for preventing the same, and more particularly, to a carbonaceous lump powder (including a relatively large lump from a granular material) such as coal or carbon black. The present invention relates to an agent for preventing heat generation and ignition that can prevent spontaneous heat or spontaneous ignition that occurs when stacked or loaded, and a method for preventing the same.
[0002]
[Prior art]
When storing large amounts of coal and carbon black at power plants, steelworks, etc., heat and ignition may occur inside the loaded coal. Prevents spontaneous ignition of coal.
Conventionally, such an exothermic / igniting preventive agent includes at least one kind of a temperature increasing / spontaneous ignition inhibitor containing at least one substance selected from a radical scavenger and an oxygen scavenger, and one or more nonionic surfactants. There have been proposed heat-up / spontaneous ignition inhibitors and the like.
[0003]
In addition, in the case of coal storage in an indoor silo, in the case of single-point storage, the angle of repose at the time of stacking is 35 to 45 degrees, and lump coal is easily deposited around the silo wall. If a large amount or a long period of stay exists around these silos, air is sucked in from the gap between the lump coals at the payout port, and the boundary between the lump coal and the pulverized coal is most likely to occur. Also, when piled up evenly with a rotating stacking machine, compared to single-point stacking, the flow of air is smaller, so the heat generation is slightly slower, but the point where heat is generated cannot be specified. . If the water in the lump coal evaporates due to heat generation, the air passage can be more easily made to the upper part of the silo, and the air permeability improves, resulting in a chimney effect due to the temperature difference between the temperature of the air above the silo and the lump coal, and natural ventilation Promotes and accelerates spontaneous combustion.
[0004]
By the way, in the heat generation / ignition prevention including the conventional radical scavenger and oxygen scavenger, although a certain effect is seen in terms of carbonaceous reforming, the ventilation path of the carbonaceous mass to be loaded or stacked is provided. Cannot be blocked. For this reason, prevention of heat generation and ignition cannot be sufficiently prevented. In addition, even if such a heat generation / ignition prevention agent is sprayed at the outlet under the silo, it does not have any effect on the lump coal deposited around the silo wall, and generates sufficient heat / ignition. It cannot be prevented. In addition, the use of such a chemical product has a problem of high cost.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the problems and the current state of the prior art described above, and is intended to solve the problem. When the carbonaceous bulk powder such as coal and carbon blacks is stacked and stored, particularly, the stacked storage of silos is performed. An object of the present invention is to provide an agent for preventing heat and ignition of carbonaceous mass powder, which can sufficiently suppress heat and ignition at the time, and a method for preventing the same.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on the above-mentioned problems of the prior art and the like, and as a result, the aqueous solution of sodium alginate frequently used for industrial and food processing can easily adjust the viscosity of the solution and can easily control gelation. Since it is possible to appropriately adjust the hardness and the like of the gel, it has been found that in order to block ventilation from a portion where coal is exposed, such as a silo, it is possible to efficiently coat the exposed surface of coal by gelation of alginic acid. Thus, the present invention has been completed.
[0007]
That is, the heat generation / ignition prevention agent and the method for preventing the same according to the present invention are characterized by the following constitutions and structures.
The heat generation / ignition preventive agent according to the present invention is characterized by comprising an alginic acid aqueous solution.
Alginic acid is a polysaccharide contained in shoots and kelp, and is industrially purified and used for foods, cosmetics, pharmaceuticals, and the like. Alginic acid is insoluble in cold water in the free acid state and slightly soluble in hot water. Alginic acid and alkali metal and ammonium salts are usually dissolved in water to form a viscous solution, but no gel is formed. Therefore, the aqueous alginic acid solution in the present invention is an aqueous solution of an alkali metal salt such as an ammonium salt, a sodium salt, and a potassium salt. Therefore, it is desirable that the alginic acid in the aqueous solution is dissolved as an aqueous solution of an alkali metal salt such as a sodium salt or an ammonium salt.
[0008]
The alginic acid aqueous solution easily gels when a small amount of hydrochloric acid or the like is added to generate free alginic acid in the solution, and also easily gels with other metal salts other than alkali metals, for example, alkaline earth metals such as calcium. I do.
When the alginic acid aqueous solution is directly sprayed on the carbonaceous pulverized lump coal, the viscous alginic acid aqueous solution enters the gaps between the pulverized lump coals, and when the metal such as the acid or calcium is further dispersed as a hardener, the voids are formed. Alginic acid gels to form a film. This prevents infiltration of air and the like into the piled lump coal, thereby preventing heat generation and ignition of the piled or loaded carbonaceous lump coal.
[0009]
The curing agent used in the aqueous alginic acid solution is preferably an acid or a metal salt other than an alkali metal. In particular, it is desirable to use an alkaline earth metal such as calcium as the curing agent. For example, when calcium chloride is used as a hardening agent, a gelled product does not disappear with drying, forms a flexible film, and is dried as compared with the case where an acid such as hydrochloric acid is used. However, the coating remains, and does not disappear or swell even when water is sprayed again to immerse the coating in water, and the coating function can be sufficiently maintained.
[0010]
Therefore, the method for preventing heat generation and ignition according to the present invention is characterized in that a gel coating is formed on the stacked carbonaceous mass powder using an alginic acid aqueous solution and a curing agent for gelling alginic acid. it can.
The method for preventing heat generation and ignition according to the present invention is applied to a coal storage yard where carbonaceous lump powder is loaded, or a stack silo or the like in which carbonaceous lump powder is supplied from the upper portion and discharged from a lower conveyor or the like. It can be used and is desirably used for carbonaceous mass powder that is piled up in silos where air passages are likely to occur. In particular, when the above-described alginate aqueous solution is used for carbonaceous lump coal stacked at the outlet of the stack silo for carbonaceous lump, the air flow of the carbonaceous lump stored in the silo can be efficiently performed. It shuts off well to prevent heat generation and ignition.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a perspective view of a coal storage to which a method for preventing heat generation and ignition according to the present invention is applied. FIG. 2 is a schematic diagram showing a part of a coal storage base in which a silo to which the method of preventing heat generation and ignition according to the present invention is applied is installed. FIG. 3 is a side sectional view of a silo to which the method for preventing heat generation and ignition according to the present invention is applied. FIG. 4 is a front sectional view of a silo to which the method for preventing heat generation and ignition according to the present invention is applied. FIG. 5 is a perspective view near the payout of a silo to which the method of preventing heat generation and ignition according to the present invention is applied. FIG. 6 is a schematic diagram showing points in a silo to which the method for preventing heat generation and ignition according to the present invention is applied.
[0012]
The agent for preventing heat generation and ignition of the carbonaceous pulverized lump coal according to the present invention is characterized by comprising an aqueous alginic acid solution.
The aqueous alginic acid solution is obtained by dissolving an alkali metal salt such as sodium alginate or ammonium alginate or ammonium in water. Sodium alginate and the like are polysaccharides contained in young shoots and kelp, and are industrially purified and used for foods, cosmetics, pharmaceuticals and the like. Specific examples thereof include duck algin NSPH2 for food additives, duck algin NSPH (Kibun Food Chemifa Co., Ltd.), and Algitex M (Kimika Co., Ltd.) for general industrial use.
[0013]
The concentration of alginic acid in the alginic acid aqueous solution is preferably in the range of 0.5 to 3.0% aqueous solution, more preferably in the range of 0.8 to 1.5% aqueous solution. It is desirable that If the alginic acid concentration is below the above range, a sufficient amount does not exist even if the alginic acid is gelled after spraying, so that the film may not be sufficiently formed on the lump coal to be stacked. On the other hand, if it exceeds the above range, the aqueous alginic acid solution becomes viscous, so that it cannot be easily handled and manufactured.
[0014]
In the present invention, the alginic acid aqueous solution preferably has a viscosity in the range of 300 to 10000 cp, depending on the size of the lump coal used. The viscosity of the aqueous alginic acid solution is affected by the alginic acid concentration and the temperature, and the appropriate value of the viscosity during use varies depending on the size of the lump coal used. For example, when the lump coal diameter (the diameter of the long diameter portion) is less than 30 mm, the viscosity of the alginate aqueous solution is desirably in the range of 300 to 500 cp, and the lump coal diameter (the diameter of the long diameter portion) is less than 30 to less than 50 mm. When the alginate solution is contained, the viscosity of the aqueous alginate solution is desirably in the range of 500 to 1000 cp. When the bulk coal diameter (diameter of the major portion) is 50 mm or more, the viscosity of the alginate solution is 3000 cp or more. In particular, it is desirable to be 10,000 cp or more. If the diameter of the lump coal is increased, the voids of the lump coal to be stacked are relatively large. In this case, it is preferable that the alginic acid aqueous solution to be sprayed has a high viscosity.
[0015]
Examples of the carbonaceous lump powder of the present invention include, for example, anthracite, bituminous coal, subbituminous coal, coal such as lignite, petroleum coke, carbon black by-produced from a chemical plant, carbon black obtained by carbonizing organic matter, Examples thereof include those used as energy sources such as charcoal. Preferred for its use is coal. Such lump powder has a diameter of 70 mm depending on the coal mining area, and generally has a maximum particle diameter of 30 to 50 mm.
[0016]
In the present invention, the number of times of spraying the alginic acid aqueous solution is not particularly limited, but it is preferable to alternately spray the solution with a curing agent described later two times or more, particularly five times or more. After spraying, water is evaporated for about several hours, and when the strength of the film has increased to some extent, a strong film can be formed by spraying again, that is, by repeating several times. It is particularly desirable to use such spraying for lump coal whose maximum diameter exceeds 50 mm.
[0017]
In the present invention, as described above, the curing agent for gelling the aqueous alginic acid solution is an acid or a metal salt other than an alkali metal.
Alginic acid is generally hardly soluble in water as a free acid, and alginic acid can be gelled by adding an acid such as hydrochloric acid to an alginic acid aqueous solution. Gelation also occurs when a metal salt other than an alkali metal is added to an aqueous alginic acid solution. Due to such properties of alginic acid, the above-mentioned acids or metal salts other than alkali metals can be effectively used as a curing agent for the aqueous alginic acid solution.
In particular, when calcium chloride or the like is used as a hardening agent, not only a sufficient gel coating is formed on the surface of lump coal, but also a stable gel coating can be obtained. The concentration of the aqueous solution of calcium chloride as a curing agent is desirably used in the range of 3 to 20% by mass.
[0018]
The heat generation / ignition prevention method according to the present invention uses the heat generation / ignition prevention agent, and uses an alginic acid aqueous solution and a curing agent that gels alginic acid to form a gel on the stacked carbonaceous mass powder. It is characterized by forming a coating.
The method of spraying the alginic acid aqueous solution on the carbonaceous mass powder to be stacked may be spraying with a high-pressure nozzle, or may be applied to the surface as long as the method can uniformly spray the surface of the stacked mass powder. It may be something. The application method is not limited as long as the coating is uniformly and sufficiently formed.
Further, the alginic acid aqueous solution and the curing agent may be sprayed almost simultaneously, or the alginic acid aqueous solution and the curing agent may be alternately sprayed. And it is desirable to repeat spraying according to the gelling film on the piled coal powder surface.
[0019]
The above-mentioned piled lump powder is not limited to one loaded in an indoor silo to be described later, and can be used, for example, in an outdoor loading and storage facility 1 formed in a bank shape as shown in FIG. In such a coal storage yard 1, the above-mentioned alginic acid aqueous solution is sprayed on the coal surface 1b having a height of about 5 to 6 m from the bottom 1a, and then a hardening agent is sprayed. In such a loading coal storage yard 1, the gel coating 2 is formed on the upper part thereof, and the suction of air from below is blocked, so that heat generation can be prevented.
[0020]
The present invention can be characterized in that the above-mentioned aqueous alginic acid solution is used for carbonaceous lump coal which is stacked at the outlet of a silo for carbonaceous lump.
2 to 5 are schematic sectional views of a lump coal silo to which the method for preventing heat generation and ignition according to the present invention is applied.
As shown in FIG. 2, a plurality of cylindrical coal storage silos 3 are provided side by side at the coal storage terminal, and each silo 3 is provided on four payout tunnel lines 4. The end of each payout tunnel line 4 is connected to a circulation collecting tunnel line 6 through a payout machine maintenance crane rail 5.
[0021]
As shown in FIGS. 3 and 4, a supply path 11 is provided on the roof 10 of the coal storage silo 3, and coal is introduced into the silo 3 from substantially the center of the ceiling via a conveyor in the supply path 11 (not shown). Supplied. As shown in FIG. 2, a hoist line 13 is provided on the roof 10 of the silo 3 for coal storage.
The above-mentioned payout tunnel lines 4 are disposed below the silo 3, and a drop hopper 14, a regulating rail 15 in the hopper, and a conveyor 16 below the hopper are provided in the tunnel line 4.
[0022]
As shown in FIG. 5, a payout port 18 having a width of about 400 mm is formed between the table portion 17 of the drop hopper 14 and the regulating rail 15, and lump coal is discharged from the payout port 18 onto the conveyor 16. I have. In this case, a lump coal 19 having a relatively large particle diameter is stored or retained in a region near the inner wall of the silo 3, and pulverized coal having a relatively small particle diameter exists at a position away from the inner wall. For this reason, air is taken in from the payout port 18 near the inner wall of the silo 3, and the region A near the inner wall of the silo 3 is easily heated and heated.
[0023]
In the method for preventing ignition and heat generation according to the present invention, a spray tube 21 is provided on the side surface of the lower end of the regulating rail 15, and a spray nozzle is formed in the tube 21. The above-mentioned aqueous alginic acid solution, which is an agent for preventing heat generation and ignition, is sprayed from the spray nozzle. In particular, it is indispensably installed at the lower end of the regulation rail 15 near the inner wall surface of the silo 3. Similarly, another spray pipe 22 is provided at the lower end of the regulating rail 15, and a spray nozzle is formed in the other pipe 22. An aqueous solution of calcium chloride as a curing agent is sprayed from the spray nozzle.
[0024]
In such a configuration, the alginic acid aqueous solution and the calcium chloride aqueous solution may be separately sprayed, and when the bulk powder contains relatively large particles, for example, 50 mm or more, particularly 70 mm in diameter. If so, it is desirable to spray the alginic acid aqueous solution and the calcium chloride aqueous solution almost simultaneously. Further, in the case of treating such a large lump of powder, the viscosity of the alginic acid aqueous solution is desirably 3000 cp or more, and particularly desirably 10,000 cp or more. If such simultaneous spraying and the use of a high-viscosity alginic acid aqueous solution are used, it is possible to efficiently close relatively large gaps in the bulk powder and form a film.
In order to sufficiently form a coating on the surface of the bulk powder, the application of the aqueous alginic acid solution and the aqueous calcium chloride solution may be repeated a plurality of times.
[0025]
By such a method of preventing heat generation and ignition, an alginate gel coating that does not allow air to pass through is formed on the surface of the piled coal in the vicinity of the inner peripheral wall of the silo 3. For this reason, the air from the payout port 18 does not enter the piled lump coal, the lump coal cannot serve as a passage for air, the coal does not generate heat, and there is a risk of spontaneous ignition. Nor.
The heat generation / ignition preventive agent or method for preventing heat generation and ignition comprising such an alginic acid aqueous solution is effective in "(1) Prevention of coal heat generation."
(2) By suppressing heat generation in the silo, loss of coal heat generation can be reduced.
(3) It is excellent in safety because it uses food additives.
(4) Easy handling because lump coal does not adhere to each other.
(5) Low cost.
(6) Equipment can be easily automated due to the construction method. And so on.
[0026]
In the above-described embodiment, a hose-type spray nozzle is provided on the regulating rail 15 to spray the alginic acid aqueous solution. However, the present invention is not limited to this. Spraying may be performed using a spray nozzle or using a spray pump.
In addition, in order to avoid the deterioration of alginic acid, it is desirable to add an alginic acid stabilizer, a preservative and the like to the aqueous solution.
[0027]
【Example】
Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.
[0028]
(Example 1)
At the time of Indonesian coal storage where natural heat generation is fast, as shown in FIG. 6 (a), at a point 32 close to the inner wall surface near the conveyor 5 of the silo 3 where a large amount of air is sucked, a 1% sodium alginate solution and a hardener are used. A 3.6% hydrochloric acid solution was used. Both solutions were alternately applied three times to form a gelled film, and the inflow of air on the surface of the coal storage, which is one of the indicators of spontaneous heat generation, was confirmed using an anemometer.
[0029]
Before the formation of the gelled film, the anemometer was 0.8 m / sec, and the air inflow from this point was 0.64 m ³ / sec because the cross-sectional area was 0.8 m ² . After the formation of the gel film, it was 0.05 m / s with an anemometer, and the air inflow was reduced to 0.04 m ³ / sec, which was 1/15 or less, confirming the effectiveness of the present method.
[0030]
(Example 2)
Furthermore, a long-term coal storage test for 34 days was conducted using Australian coal that generates heat relatively quickly. Of the 16 points (31 to 46 shown in FIG. 13B) which are close to the inner wall surface where the amount of air sucked into the silo is large, the point 32 is left as it is, and the remaining 15 points are filled with each sodium alginate solution and the curing agent. The mixture was sprayed alternately 3 to 8 times to form a gel film, and the state of spontaneous heat generation was observed.
[0031]
As a result, on the 34th day, steam at a temperature of 50 ° C. was generated from the upper part of the silo at the point 32 where no gelling film was formed, and the off-flavor generated when the coal smoked was generated at the upper and lower parts of the silo at the point. The test was interrupted due to the occurrence of
As described above, it was confirmed that the inflow of air can be cut off and the spontaneous heat generation can be efficiently suppressed by reliably covering the point close to the inner wall surface of the silo 3 where the air suction amount is large with the gelling film. .
[0032]
In addition, when hydrochloric acid is used as a curing agent, it gels into a jelly-like form and disappears with drying, whereas when calcium chloride is used as a curing agent, a flexible film is formed and dried. Also remained as a film, and it was found that the film disappeared and did not swell even when immersed again in water. In addition, it was understood that the calcium chloride solution was more excellent in terms of safety.
[0033]
【The invention's effect】
Since the heat generation / ignition prevention agent of the present invention comprises an alginate aqueous solution, the heat generation / ignition prevention method of the present invention for preventing ignition and heat generation uses such an alginic acid aqueous solution and a curing agent for gelling alginic acid. Therefore, a gel coating is formed on the stacked carbonaceous mass powder, so that heat and ignition during the stacking storage of carbonaceous mass powder such as coal and carbon black, particularly during the stacking storage of silos, etc., are reduced. It can be suppressed sufficiently.
[Brief description of the drawings]
FIG. 1 is a perspective view of a coal storage to which a method for preventing heat generation and ignition according to the present invention is applied.
FIG. 2 is a schematic view showing a part of a coal storage base provided with a silo to which the method for preventing heat generation and ignition according to the present invention is applied.
FIG. 3 is a side sectional view of a silo to which the method for preventing heat generation and ignition according to the present invention is applied;
FIG. 4 is a front sectional view of a silo to which the method for preventing heat generation and ignition according to the present invention is applied;
FIG. 5 is a perspective view of the vicinity of dispensing a silo to which the method for preventing heat generation and ignition according to the present invention is applied.
6 (a) and 6 (b) are schematic diagrams showing points in a silo to which the method for preventing heat generation and ignition according to the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coal storage 2 Gel coating 3 Silo 4 Discharge tunnel 14 Drop hopper 15 Restriction rail 16 Conveyor 18 Discharge port 19 Coal lump 21 Spray pipe 22 Spray pipe

Claims (5)

An agent for preventing heat and ignition of carbonaceous piled pulverized coal, comprising an aqueous alginate solution. The heat / ignition preventive agent according to claim 1, wherein the alginic acid in the aqueous solution is dissolved as an aqueous solution of sodium alginate or ammonium alginate. The heat generation / ignition prevention agent according to claim 2, wherein the curing agent for gelling the aqueous alginic acid solution is a solution of a metal salt other than an acid or an alkali metal. A method for preventing heat generation and ignition for preventing ignition and heat generation, wherein a gel coating is formed on stacked carbonaceous mass powders using an alginic acid aqueous solution and a curing agent for gelling alginic acid. The method for preventing heat generation and ignition according to claim 4, wherein the aqueous alginic acid solution is used for carbonaceous lump coal which is stacked at a discharge port of a stack silo of carbonaceous lump powder.

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