JP2008012158A - Fire-extinguishing method of pool fire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which enables of the extinction of pool fire over a short period of time with less amount of water mists. <P>SOLUTION: Described herein is a fire-extinguishing method of a pool fire utilizing water mists, wherein the water mists are discharged so as to surround the flame base portion of a pool fire virtually without a gap, directed not to the burning surface and the flame base portion directly, but to any of positions of the flame center axis from a plurality of positions on the side of the burning surface, while water mists are being discharged toward the flame center axis above the flame base portion from a plurality of positions above the burning surface, so that the fire is extinguished. Preferably, the discharge of water mist from the side of the burning surface is performed prior to the discharge of water mist from above the burning surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for extinguishing a pool fire caused by oil or the like. More specifically, the flame base is surrounded from the side of the combustion surface toward the flame center axis (a line connecting the center of the flame base and the flame apex) with almost no gap. The present invention relates to a method for effectively extinguishing a pool fire by radiating water mist and radiating water mist downward from above a combustion surface toward a flame central axis.

  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 performing fire extinguishing with a water mist in a short time with a small amount of water in a pool fire.

  As a method for achieving such an object, the present inventor disclosed in Japanese Patent Application No. 2006-74331 by using a water mist by a downward flow formed by a water mist radiated from the periphery above the combustion surface toward the flame central axis. In addition to the cooling effect, it is possible to sufficiently exhibit the effect of suppressing air inflow due to the generation of water vapor and the increase in pressure inside the flame, and in Japanese Patent Application No. 2006-138484, it is emitted from the side of the combustion surface toward the flame center axis. It was proposed that the suffocation effect by changing the air flow can be sufficiently exhibited by surrounding the flame base with the water mist by the side flow formed by the water mist, in addition to the effect by the phase change of the water mist.

  However, as a result of studying these methods by the present inventor, when only the downward flow of the water mist is used, even if a free board is present, the water mist tends to enter the flame base and extinguish the fire, but the downward flow is brought to the combustion surface. When it reaches, there may be a problem that the flame expands in the lateral direction due to the pressure inside the flame, and when only the lateral flow of water mist is used, the lateral expansion of the flame during fire extinguishing is However, it was found that the presence of a free board makes it difficult for the water mist to go around the flame base and the flame remains at the edge and cannot be completely extinguished.

  Furthermore, as a result of intensive studies based on such knowledge, the present inventor has found that the disadvantages of the water mist downward flow and the lateral flow can be overcome by the mutual advantages of the two by using both of the problems. It was completed.

  That is, according to the present invention, in a method for extinguishing a pool fire by water mist, a pool fire is not directed from a plurality of locations on the side of the combustion surface directly to the combustion surface and the flame base but to any position of the flame center axis. The water mist is radiated so as to surround the flame base substantially without any gap, and the fire is extinguished by radiating the water mist from a plurality of locations above the combustion surface toward the flame central axis above the flame base. Is the method.

  In a preferred embodiment of the method according to the invention, the water mist radiation from the side of the combustion surface takes place prior to the water mist radiation from above the combustion surface. Further, in a preferred embodiment of the method of the present invention, a plurality of nozzles capable of radiating water mist are provided at equal intervals around the combustion surface so as to surround the combustion surface, and these nozzles have a flame center above the combustion surface. The water mist is emitted so that it is directed to any position on the shaft but not directly to the combustion surface and the flame base. Furthermore, in a preferred embodiment of the method of the present invention, a plurality of nozzles capable of emitting water mist are provided at equal intervals on a horizontal plane above the combustion surface and on a circle centered on the flame central axis, and these nozzles are provided. Water mist is emitted so as to be directed to any position on the flame center axis below the horizontal plane but not directed directly to the combustion surface and the flame base.

  The method of the present invention radiates water mist from the side of the combustion surface toward the flame center axis so as to surround the flame base, and radiates water mist from above the combustion surface toward the flame center axis below. Therefore, in addition to the cooling effect and the oxygen concentration dilution effect due to the phase change from liquid to gas by water mist, the oxygen supply inhibition to the flame base and the suppression of oxygen inflow due to the increase in pressure inside the flame can be demonstrated significantly. As a result, the fire can be quickly extinguished with a small amount of water. Further, the problem that may occur when the radiation from the side of the combustion surface of the water mist and the radiation from above are used alone can be overcome by using both together as in the method of the present invention.

  In the method of the present invention, (i) water mist is radiated from a plurality of locations on the side of the combustion surface so as to surround the flame base so as not to be directed directly to the combustion surface and the flame base but to the flame central axis above them. And (ii) quick fire extinguishing with a small amount of water by radiating water mist from a plurality of locations above the combustion surface toward the flame center axis above the flame base. is there.

  (I) With radiation from the side of the combustion surface of the water mist, the oxygen supply to the flame base is blocked by surrounding the flame base almost without any gap, thereby reducing the amount of oxygen required for combustion and suffocating However, when there is a free board, there is a problem that the water mist is difficult to go around the flame base and the flame tends to remain at the edge. This problem is prevented by (ii) radiation from above the combustion surface of the water mist.

  As a method of radiating water mist from the side of the combustion surface toward the flame center axis, for example, an oil tank that generates a pool fire is surrounded by an equal interval around the combustion surface around the combustion surface. This can be done by laying a plurality of locations at the center of the flame and directing it to any position on the flame center axis, but not directing it to the combustion surface and the flame base, and creating a water mist wall conically. .

  The direction of emission when water mist is emitted from the side of the combustion surface is substantially parallel to the flame flow so that the water mist blocks the flow of air flowing from the flame base to the flame center during combustion. And in the same direction. 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.

  (Ii) When the water mist is emitted from above the combustion surface, the water mist radiated from a plurality of locations above the combustion surface toward the flame central axis above the flame base collides with each other and descends in the flame. The water vapor collides with the flame to become water vapor by the heat energy of the flame, and this water vapor is expanded to more than 1000 times the volume of the water mist. As a result, the internal pressure of the flame increases, the surrounding oxygen concentration decreases, and the inflow of oxygen into the flame base is suppressed, leading to extinguishing. Further, the phase change from liquid to gas by the water mist is performed on the combustion surface, the flame is moved away from the combustion surface, the ignition energy necessary for the combustion chain is lost, and the fire is extinguished. In this method, there is a problem that when the downward flow of the water mist reaches the combustion surface, a phenomenon in which the flame expands in the lateral direction due to an increase in the pressure inside the flame. This problem is prevented by (i) radiation from the side of the combustion surface of the water mist. In this case, since the lateral expansion of the flame occurs when the downward flow of the water mist reaches the combustion surface, (ii) radiation from the side of the combustion surface of the water mist is performed before reaching the downward flow. Is preferred.

  As a method of radiating water mist from above the combustion surface toward the flame center axis, for example, nozzles that can radiate water mist on a circle centered on the flame center axis on the horizontal plane formed above the combustion surface are evenly distributed. It can be performed by providing a plurality of locations at a certain interval. However, in this case, each nozzle directs the water mist to any position on the flame center axis below the horizontal plane, but directly to the combustion surface and the flame base for the reason of avoiding the air surrounding the flame. It is preferable not to do so. The radiant flow velocity of the water mist from above needs to be a speed at which the water mist is not rolled up by a flame and does not cover the flame, and is actually preferably 1 m / s to 3 m / s.

  Further, the horizontal cross-sectional area of the water mist downflow is preferably smaller than the combustion area so that the water mist downflow is extinguished from below toward the edge of the flame, and accordingly, a horizontal plane in which each nozzle is provided around. It is preferable to make the area of the upper circle smaller than the combustion area of the oil surface.

  Water mist can be generated by any conventionally known method, and can be radiated on the same principle as a fire extinguisher described in, for example, Japanese Patent Application Laid-Open No. 2004-135742. The average particle size of the emitted water mist is usually 10 μm to 500 μm, preferably 10 μm to 200 μm in the case of radiation from the side, and preferably 50 μm to 500 μm in the case of radiation from the top. In the case of radiation from the side, if the particle size is smaller than the above lower limit, it will be vaporized into water vapor before reaching the flame due to the radiant heat of the flame, and if the particle size is larger than the upper limit, it will be completely after passing through the flame Since it does not evaporate and a water droplet remains, it is not preferable. In addition, in the case of radiation from above, if the particle size is smaller than the lower limit, the flame is wound up and the thermal energy of the flame cannot be sufficiently absorbed, and if the particle size is larger than the upper limit, water droplets remain after passing through the flame. It is not preferable.

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

Reference 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 °. Next, 48 liters of n-heptane was put into the oil tank and ignited, and the flame base was surrounded by the above injection method without any gaps. The fire extinguishing time and water consumption were 17 seconds and 13.6 liters, 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.

Reference example 2
As shown in FIG. 2, a circular oil tank having a diameter of 1440 mm and a depth of 300 mm is prepared, and a flame center axis (vertical center axis of the oil tank) is 1210 mm in diameter on a horizontal plane 990 mm above the edge of the oil tank. Twenty-four water mist generating nozzles were equally installed on the circle so that water mist with an average particle diameter of 100 μm could be sprayed from the horizontal plane toward the flame central axis at a spray angle of 30 ° and a spray range of 60 °. Next, n-heptane was introduced to a depth of 150 mm in a circular oil tank and ignited, and when the fire was extinguished by injecting water mist toward the flame center axis instead of the combustion surface and flame base by the above injection method, the fire extinguishing time Was 21 seconds. The water pressure during the water mist injection was 0.9 MPa, the water flow rate was 48 l / min, and the amount of water used was 16.8 l.

Example 1
As shown in FIG. 3, 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 evenly installed around the oil tank, and a 30 ° jet is directed toward the upper center of the oil tank. A water mist with an average particle diameter of 100 μm can be sprayed at an angle of 60 °, and a diameter of 1250 mm centering on the flame center axis (vertical center axis of the oil tank) on a horizontal plane 990 mm above the edge of the oil tank. Sixteen water mist generating nozzles were equally installed on the circle, so that water mist with an average of 100 μm could be sprayed at a spray angle of 15 ° and a spray range of 60 ° from the horizontal plane toward the flame center axis. Next, n-heptane is inserted to a depth of 150 mm in a circular oil tank and ignited. The injection from the edge of the oil tank is started 4 seconds faster than the injection from the top of the oil tank. In the case of the injection from above, the flame base was surrounded without any gap, and in the case of the injection from above the oil tank, the fire extinguishing time was 13 seconds when water mist was injected toward the flame center axis instead of the combustion surface and the flame base. It was. The water pressure at the time of water mist injection is 0.9 MPa, the water flow rate and the amount of water used are 32 l / min, 6.4 l for injection from above the oil tank, and 9.6 l / min for injection from the edge of the oil tank. 2.1 l, and the water mist radiation flow rate at a distance of 20 cm from the nozzle outlet disposed around the oil tank was 3 m / s.

  As is clear from the results of Reference Example 1, Reference Example 2 and Example 1 above, radiation from the edge of the oil tank and radiation from the edge of the oil tank and the upper part of the oil tank are performed independently from the radiation from the edge of the oil tank. The fire-extinguishing method using radiation from the water can quickly extinguish with a small amount of water.

  According to the method of the present invention, the fire extinguishing of the pool fire can be performed quickly and reliably with a small amount of water by using the side flow and the downflow of the water mist in combination, so it is extremely useful for extinguishing the place where the pool fire can occur Useful.

It is the schematic which shows an example of the fire extinguishing method of the reference example 1. FIG. It is the schematic which shows an example of the fire extinguishing method of the reference example 2, (a) is the top view, (b) shows the elevation. It is the schematic which shows an example of the fire extinguishing method of this invention, (a) is the top view, (b) shows the elevation view.

Claims (4)

  In the method of extinguishing a pool fire with water mist, the flame base of the pool fire is not nearly directly directed from the multiple points on the side of the combustion surface to the combustion surface and the flame base but to any position on the flame center axis. A method characterized by radiating water mist so as to surround it and extinguishing fire by radiating water mist from a plurality of locations above the combustion surface toward the flame central axis above the flame base.   The method according to claim 1, wherein the water mist radiation from the side of the combustion surface is performed prior to the water mist radiation from above the combustion surface.   Around the combustion surface, a plurality of nozzles capable of emitting water mist are provided at equal intervals so as to surround the combustion surface, and these nozzles are directed to any position on the flame center axis above the combustion surface. The method according to claim 1, wherein the water mist is emitted so as not to be directed directly to the flame base.   A plurality of nozzles that can radiate water mist are provided at equal intervals on a horizontal plane above the combustion surface and centered on the flame central axis, and these nozzles are any one of the flame central axes below the horizontal plane. The method according to any one of claims 1 to 3, wherein the water mist is radiated so that the water mist is directed to the position but not directly to the combustion surface and the flame base.

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