JP2007307096A - Fire-extinguishing method of pool fire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of effectively fire-extinguishing a pool fire by water mists. <P>SOLUTION: In the fire-extinguishing method of a pool fire by the water mists, by discharging the water mists so as to surround the flame base portion of a pool fire virtually without a gap in the direction of not to the burning surface and the flame base portion directly but to any of positions of the flame center axis, oxygen supply to the flame base portion is blocked by steam generated from the water mists and the fire is extinguished. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for extinguishing a pool fire such as oil, and more specifically, radiating water mist so as to surround the flame base almost without any gap toward the flame center axis (a line connecting the center of the flame base and the flame apex). To prevent the supply of oxygen to the flame base of the pool fire and extinguish the fire.

  Conventionally, facilities using local fire extinguishing with carbon dioxide, foam fire extinguishing, and water spraying are used as extinguishing methods for pool fires. Such equipment is constructed by installing a fire-extinguishing water pipe above an oil tank (such as a quenching tank) where a fire is expected, and having nozzles directed downward at regular intervals. Extinguish fire by radiating carbon dioxide, bubbles, and water spray toward the source.

  However, with such a method, there is a danger of suffocation for carbon dioxide, pollution to the environment for foam extinguishment, and for water spray, the water spray is simply released from the top to the bottom of the flame. However, it is difficult to extinguish the fire, and it is difficult to extinguish the fire, and there is a problem that a large amount of water must be used for that purpose.

  In order to solve this problem, there has been proposed a method of extinguishing fire by putting water mist on an air flow generated in a flame base of a pool fire and reaching the inside of the flame (see Patent Document 1).

In this method, the water mist can reach the inside of the flame, so that the cooling effect by the water vapor generated by the water mist coming into contact with the flame and the effect of lowering the oxygen concentration can be seen, but the oxygen to the flame base is the air flow. However, there is still room for improvement.
JP 2005-323794 A

  The present invention has been developed to overcome such problems of the prior art, and an object of the present invention is to provide a method capable of effectively extinguishing with water mist in a pool fire.

  As a result of diligent investigations to achieve the above object, the present inventor exhibits a suffocation effect by changing the air flow in addition to the effect due to the phase change of the water mist by surrounding the flame base with the wall of the water mist. As a result, it was found that a pool fire can be extinguished in a short time, and the present invention has been completed.

  That is, according to the present invention, in a method for extinguishing a pool fire with water mist, the flame base of the pool fire is surrounded almost without any gap so as not to be directed directly to the combustion surface and the flame base but to any position of the flame central axis. In this method, the water mist is radiated to prevent the oxygen supply to the flame base by the water vapor generated from the water mist and extinguish the fire.

  In a preferred embodiment of the method of the present invention, the water mist radiation direction is substantially parallel to the flame flow, and the radiated water mist flow rate is set to a speed sufficient to prevent air from entering the flame base. The average particle size of the emitted water mist is 10 μm to 200 μm.

  In the method of the present invention, the oxygen supply amount to the flame base is reduced by surrounding the flame base with water mist without gaps, so that the cooling effect and the oxygen concentration dilution effect due to the phase change from the liquid to the gas of the water mist are reduced. In addition, the effect of suffocation by blocking the supply of oxygen is exhibited, and as a result, rapid fire extinguishing with a small amount of water is possible.

  The method of the present invention is a method in which a pool fire can be extinguished in a short time with water mist. The water mist surrounds the flame base almost without any gap so that the supply of oxygen to the flame base is prevented, thereby necessitating combustion. The amount of oxygen supplied is reduced to suffocate and extinguish.

  Water mist can be generated by any conventionally known method, but can be radiated on the same principle as a fire extinguisher described in, for example, Japanese Patent Application Laid-Open No. 2004-135742. In order to maximize the fire-extinguishing effect, it is desirable that the water mist is completely changed to water vapor after passing through the flame. The average particle size of the water mist is preferably 10 μm to 200 μm. If it is less than 10 μm, it will be vaporized into water vapor before it reaches the flame due to the radiant heat of the flame, and if it exceeds 200 μm, it will not vaporize completely after passing through the flame and water droplets will remain.

  As a method of surrounding the flame base with water mist without gaps, for example, a plurality of nozzles that produce water mist are evenly installed around an oil tank that produces a pool fire, and the water mist is emitted toward the air inflow direction of the flame base. This can be done by creating a water mist wall conically.

  The water mist radiation direction is preferably substantially parallel to and in the same direction as the flame flow so that the water mist prevents air flow from the flame base to the flame center during combustion. Moreover, it is preferable that the radiant flow velocity of the water mist is a velocity sufficient to prevent air from flowing into the flame base, and is actually preferably 0.1 m / s to 10 m / s, preferably 0.3 m / s to 6 m / s is more preferable.

  Although the effect is shown by an example of the method of this invention below, this invention is not limited to this.

Example 1
As shown in FIG. 1, a circular oil tank having a diameter of 1440 mm and a depth of 300 mm is prepared, and 24 water mist generating nozzles are equally installed around the oil tank, and an injection angle of 30 ° toward the upper center of the oil tank The water mist having an average particle diameter of 100 μm can be sprayed in a spraying range of 60 °. When 48 l of n-heptane was put into an oil tank and ignited, and the fire base was surrounded by the above injection method without any gaps, the fire extinguishing time and water consumption were 17 seconds and 13.6 l, respectively. The water pressure during the water mist injection was 0.9 MPa, the water flow rate was 48 l / min, and the water mist radiation flow rate at a distance of 20 cm from the nozzle outlet was 5 m / s.

Comparative Example In the method of Example 1, when the fire was extinguished in the same manner as in Example 1 except that the nozzle injection angle was set to 90 ° from the surface of the oil tank, a slight flame suppression effect was seen, but after 5 minutes. But it did not extinguish.

  According to the method of the present invention, extinguishing of a pool fire can be performed quickly and reliably with a small amount of water by forming a wall of water mist, which is extremely useful in industries where a pool fire can occur. For example, in a full fire of a dangerous goods storage tank, a water mist generating nozzle is disposed on the roof of the tank according to the method of the present invention, and the water mist is radiated to prevent oxygen supply to the flame base, thereby extinguishing the flame. Can be performed quickly and reliably.

It is the schematic which shows an example of the fire extinguishing method of this invention.

Claims (4)

  In the fire extinguishing method of pool fire by water mist, water mist is radiated so as to surround the flame base of the pool fire almost without any gap so that it is not directed directly to the combustion surface and the flame base but to any position of the flame center axis. A method characterized in that the water supply from the water mist prevents the supply of oxygen to the flame base and extinguishes the fire.   2. A method according to claim 1, characterized in that the water mist radiation direction is substantially parallel to the flame flow.   3. The method according to claim 1, wherein the flow rate of the radiated water mist is set to a speed sufficient to prevent air from flowing into the flame base.   The method according to any one of claims 1 to 3, wherein the average particle size of the radiated water mist is 10 µm to 200 µm.

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