JPH10201875A - Fire extinguisher for metal fire and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fire extinguisher for a metal fire which is used for extinguishment of the metal fire by smothering and is granulated and a process for producing the same. SOLUTION: This fire extinguisher for the metal fire consists of, for example, sodium carbonate anhydride, potassium carbonate anhydride and lithium carbonate anhydride as bases. These raw materials are granulated after mixing. If the sizes of the granulation are made too large in the particle sizes (diameters), the spacings among the particles increase and the easy flow of the air and the difficulty in the melting of chemicals are resulted. On the other hand, if the particle sizes of the granules are made too small, the exact shooting of the chemicals to a distant place is no more possible. The particle size are determined within the range of 0.3 to 10 millimeters suitable for the fire extinguisher for the metal fire by taking various kinds of raw materials, etc., into consideration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire extinguishing agent for a metal fire and a method for producing the same, and more particularly to a granulated fire extinguishing agent for a metal fire used for suffocating fires in a metal fire and a method for producing the same.

[0002]

2. Description of the Related Art In a nuclear reactor using fast neutrons for a chain reaction, liquid sodium or a mixture of sodium and potassium is used as a heating medium for the reactor. If the medium is broken in the air in the air, the leaked high-temperature medium will ignite and cause a serious accident. In addition, fires often occur from these metals even in establishments that cut magnesium, aluminum or titanium. Unlike a fire of oil or wood, such a metal fire is characterized in that the temperature of the metal itself is high and the size of the generated flame is small. For this reason, suffocation fire extinguishing is performed in which the surface of the metal itself is covered with a fire extinguishing agent to block air. Here, it is conceivable to perform fire extinguishing by suffocation with dry sand or the like, but a large amount of dry sand or the like is required to completely cover the metal surface without excessively large particles. For this reason, a metal fire extinguishing agent has been developed in which the particle diameter is as small as possible and the eutectic point is lower than the temperature of the metal itself (for example, 397 degrees) (Japanese Patent Publication No. 6-6176). By reducing the diameter of the particles, gaps between the particles can be easily filled. That is, the particle size of the fire extinguisher (hereinafter, referred to as a drug) is usually used in the range of several tens of microns to about 200 microns. In addition, since the eutectic point is lowered, the medicine is easily melted by the heat of the burning metal.
As a result, the entire surface of the metal is covered with the molten chemical and the air is completely shut off to extinguish the fire. For this reason, the amount of the fire extinguisher for metal fires is much smaller than that of dry sand.

[0003]

However, in the case of a metal fire extinguishing agent having a small particle diameter as described above, when a metal fire occurs in a distant place, when the agent is pressurized and discharged toward a fire spot, it forms a cloud. There is a possibility that the amount of the drug scattered and actually attached to the surface of the metal may be reduced. For this reason, a predetermined amount of the medicine is released at a time from a position immediately above the flame in a vertical state or a state close to the vertical state in accordance with gravity, and 1 to 2
It was necessary to cover the metal surface to a thickness of centimeters. Also, with such a technique of releasing a predetermined amount of the medicine in a vertical state or the like, it may be difficult to uniformly cover the surface of the metal with the medicine when a metal fire occurs in a wide area.

[0004] The present invention has been made in view of such a conventional problem, and the invention according to claims 1 and 2 of the present invention makes it possible to uniformly spray a chemical against a metal fire generated in a distant place. It is an object of the present invention to provide a metal fire extinguisher in which a medicine is granulated to a predetermined size.
It is an object of the present invention to provide a method for producing a fire extinguishing agent for a metal fire.

[0005]

In order to achieve the above object, the invention according to claim 1 of the present invention is a granule having a particle diameter of 0.3 mm or more and 10 mm or less of a fire extinguisher for metal fires. It is characterized by the following. The particle diameter means, for example, the diameter of a spherical granule, and the diameter of a sphere circumscribing the granule for a granule of an arbitrary shape including a cube, a column, a cone, and the like. The reason why the minimum value of the granules is set to 0.3 mm is that if the particle diameter is too small, the fire extinguisher cannot be scattered like a cloud and cannot be scattered far. On the other hand, the maximum value of granules is 10
The reason why the diameter is set to millimeters is that if the particle diameter is too large, the gap between the particles becomes large, so that air can easily flow or be hardly melted.

Here, the raw material or the like consisting of a single component may have the above-mentioned particle size. However, as in the second aspect of the present invention, a plurality of raw materials constituting a fire extinguishing agent are mixed with fine powder and granulated with a binder. It is also possible. By mixing a plurality of raw materials into fine powders and granulating them with a binder, the eutectic point can be made much lower than the combustion temperature of each metal. As a result, when this fire extinguisher is sprayed on the burning metal, the medicine is easily melted by the heat of the burning metal, the surface of the metal is covered with the melted medicine, and the air is shut off. extinguish a fire. In addition, the mixture can be made viscous to prevent the coating from cracking, and can easily adhere to pipes and the like in an actual fire place. The invention according to claim 3 of the present invention is the method for producing a metal fire extinguishing agent according to claim 1 or 2, wherein a plurality of raw materials constituting the fire extinguishing agent are pulverized and then mixed. Then, after kneading together with a binder and a solvent used to make the binder into a solution, granulating the granules to a particle size of 0.3 mm or more and 10 mm or less, and then removing the solvent by vaporization. It is characterized by. The multiple ingredients cover all substances that are effective as metal fire extinguishing agents. The reason for pulverization is that the particles of such raw materials are usually coarse and must be ground beforehand. The mixing is mainly for the purpose of lowering the eutectic point as described above. The binder is used to facilitate binding of a plurality of raw materials, and the solvent is used to make the binder into a solution so that the mixture of the raw materials has a predetermined viscosity. After a plurality of raw materials, a binder, and a solvent are kneaded, they are subjected to a granulator to form granules having a particle diameter of 0.3 mm or more and 10 mm or less. Then, by drying, the solvent is removed by vaporization. According to the above manufacturing method, a granular fire extinguishing agent for a metal fire that is easily melted by the heat of the metal and can be easily scattered can be manufactured.

Further, according to a fourth aspect of the present invention, in the method for producing a fire extinguisher for a metal fire according to the third aspect, the method for producing a fire extinguishing agent for a metal fire comprises the steps of: Characterized in that the surface treatment is performed. By performing the surface treatment of the powder before mixing or before kneading, mixing and kneading can be easily performed.

[0008]

Embodiments of the present invention will be described below. The fire extinguisher for a metal fire according to the present invention is based on, for example, anhydrous sodium carbonate, anhydrous potassium carbonate, and anhydrous lithium carbonate. However, not limited to this, for example, sodium chloride (N _a Cl) and calcium chloride (C _a
Cl ₂₎ to those with bases or, sodium chloride (N _a C
l) and may be such as those of sodium carbonate (N _a2 CO ₃₎ as a base material. These bases are mixed after micronization. By mixing a plurality of raw materials, the medicine can be easily melted by the heat of the metal in the event of a metal fire. Then, granulation is performed after the mixing. The granulation is performed so that the metal fire extinguishing agent can be easily scattered far and accurately when the metal fire spot is located far away. However, if the particle size (diameter) of the granulation is too large, the gap between the particles becomes large, so that air can easily flow or the drug is hardly melted. On the other hand, if the particle diameter of the granules is reduced, it becomes impossible to prevent the medicine from flying accurately far away by suppressing cloud-like scattering. For this reason, the particle size is limited to a predetermined range. Here, when the above-mentioned fire extinguisher is used as a base, the particle diameter is from 1 mm to 1 mm due to the above-mentioned restrictions.
It has been experimentally confirmed that a diameter of 5 mm is the easiest to handle as a fire extinguisher for metal fires. Therefore, the particle diameter is ideally 1 mm to 1.5 mm. However, when the raw materials and the like are changed, the ideal particle size may fluctuate. For this reason, considering various raw materials and the like, granules having a size of 0.3 mm or more and 10 mm or less are considered as a range suitable for a metal fire extinguisher as a range that can satisfy the above-described restrictions.

[0009] In order to granulate a drug, a binder is required to facilitate binding of raw materials. As the binder, methyl cellulose (MC), ethyl cellulose (E
C), hydroxypropylcellulose (HPC), carboxymethylcellulose (CMC), sodium alginate, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and the like are common. In addition, when performing granulation, a means for dissolving the binder is required. As a means for this dissolution, it is generally possible to use water, but if drying after granulation is not sufficient, it is conceivable that water remains in the granules. The remaining water reacts with the metal when the metal is burning, and may accelerate the combustion or cause a hydrogen explosion. Therefore, in order to realize the granulation of the fire extinguishing agent for metal fires, it is desirable to use a method that does not use water, and uses a lower alcohol such as methyl alcohol, ethyl alcohol, or propyl alcohol as a solvent for dissolving the binder. Examples of the binder dissolved in the lower alcohol include ethyl cellulose (EC), hydroxypropyl cellulose (HPC), and polyvinylpyrrolidone (PVC).
P) is excellent.

In the above-mentioned fire extinguishing agent for metal fires, the agent is melted by the heat of the metal, and the molten agent covers the surface of the metal so that even a small amount of the agent can extinguish asphyxiation. However, regarding the relationship between a metal fire extinguishing agent and a metal, there may be cases where the combustion temperature of the metal is somewhat low and the agent is difficult to melt. Even in this case, since the metal fire extinguishing agent is granulated, the surface of the metal can be uniformly covered by the granulation, and the air can be completely shut off. That is,
The present invention covers all types of metal fires (sodium, potassium, magnesium, aluminum, lithium, titanium fires, etc.)
It is a fire extinguisher for metal fires that can extinguish fire by suffocation.

Next, a method for producing a fire extinguishing agent for a metal fire will be described with reference to a flowchart. In FIG. 1, in step 1 (indicated as S1 in the figure, the same applies hereinafter), anhydrous sodium carbonate, anhydrous potassium carbonate, and anhydrous lithium carbonate as raw materials are prepared. Since the raw material particles are coarse, they are pulverized in step 3 to be pulverized. The pulverization is performed so that the raw materials are well mixed with each other. Then, mixing is performed in step 5. Mixing is performed to lower the eutectic point. The raw materials are mixed with polyvinylpyrrolidone (PVP) as a binder and methyl alcohol as a lower alcohol, and kneaded in Step 7. Methyl alcohol is easy to vaporize, so short time (about several minutes)
Ends the kneading process. Then, in step 9, granules of, for example, about 1 mm are formed by a granulator. The granules are dried in step 11 and the methyl alcohol is vaporized. Granules produced by such a granulator are spherical, cubic,
It has various shapes including a columnar shape and a conical shape. The particle size described above is, for example, the diameter for a spherical granule, and a cube,
For a columnar or conical granule, the diameter of the sphere circumscribing the granule is considered. The surface treatment may be performed between step 3 and step 5 or between step 5 and step 7. Metal stearate or the like can be used as the surface treatment agent. The surface treatment facilitates mixing and kneading.

[0012]

EXAMPLES In order to make granules having a particle size of 1 millimeter,
To 2000 g of powder based on anhydrous sodium carbonate, anhydrous potassium carbonate, and anhydrous lithium carbonate, 60 g of polyvinylpyrrolidone (PVP) as a binder and 540 g of methyl alcohol were kneaded. Further, in order to produce granules having a large particle size, it is necessary to increase the amount of the binder. To produce granules having a particle size of 1.5 millimeters, 70 grams of polyvinylpyrrolidone (PVP) and 590 grams of methyl alcohol were kneaded with 2000 grams of powder.

Next, the flying performance was tested using granules having a particle diameter of 1 mm. Using a blower with an air emission rate of 10 m ³ / min, 2-3 kg of metal fire extinguisher per minute could be blown down to a point 7 to 8 meters away with reduced cloud-like scattering. At the target point, the fire extinguisher for metal fire was uniformly scattered over an area of about 2 m ² . In addition, in the case of a dripping fire in which 750 grams of sodium leaked in a minute amount over 2 minutes, the fire extinguishing agent could be completed almost simultaneously with the termination of the leakage by spraying a metal fire extinguisher under the same conditions. .

[0014]

As described above, the present invention (claim 1)
According to the above, the fire extinguishing agent for metal fires is made into granules of a predetermined particle size, so that the medicine can be prevented from becoming cloudy and can be scattered far, and the surface of the metal fire can be uniformly covered with the medicine. I can do it. In addition, the circulation of air can be blocked by the medicine.

Further, according to the present invention (claim 2), since a plurality of raw materials are finely mixed and granulated with a binder, the eutectic point can be made much lower than the combustion temperature of each metal. Thereby, when this chemical is sprayed on the burning metal, in addition to the effect of claim 1, the chemical is easily melted by the heat of the burning metal, and the surface of the metal is melted. To cover the air and extinguish the fire.

Further, according to the present invention (claim 3), a granular fire extinguishing agent for a metal fire which can be easily melted by the heat of the metal and can be easily scattered can be produced under this production method.

Further, according to the present invention (claim 4), in the method for producing a fire extinguisher for metal fire according to claim 3, addition of a grinding aid or surface treatment of powder before mixing or kneading. By doing so, mixing and kneading can be facilitated.

[0018]

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for producing a metal fire extinguishing agent of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasunori Nozawa 2-3-12 Higashi-Shinagawa, Shinagawa-ku, Tokyo Inside Dry Chemical Co., Ltd. (72) Inventor Mitsuhiko Uchida 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi No. 1 Sanbei Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Shigenori Usui 1-1-1, Wadazakicho, Hyogo-ku, Kobe

Claims (4)

[Claims] 1. A fire extinguisher for metal fires, which is a granule having a particle size of 0.3 mm or more and 10 mm or less. 2. The method according to claim 1, wherein a plurality of raw materials constituting the fire extinguishing agent are finely mixed and granulated with a binder.
The extinguishing agent for metal fire as described. 3. A plurality of raw materials constituting a fire extinguishing agent are pulverized, mixed, kneaded together with a binder and a solvent used to make the binder into a solution, and then have a particle diameter of 0.3 mm or more. A method for producing a fire extinguisher for a metal fire, comprising granulating into granules of 10 mm or less, and thereafter removing the solvent by vaporization. 4. The method for producing a metal fire extinguisher according to claim 3, wherein a surface treatment of the powder is performed between the pulverization and the mixing or between the mixing and the kneading.