WO1997044095A1

WO1997044095A1 - Method of fire fighting in the room

Info

Publication number: WO1997044095A1
Application number: PCT/DK1997/000228
Authority: WO
Inventors: Mikhail Yurievich Sokolov
Original assignee: Ginge-Kerr Danmark A/S
Priority date: 1996-05-20
Filing date: 1997-05-20
Publication date: 1997-11-27
Also published as: AU2887797A

Abstract

It can be used in stationary fire fighting systems in closed rooms, for example, at industrial enterprises, vehicles. Is characterized by the fact that with the help of spraying nozzles located in the upper and lower zones of the protected room the in turn delivery of finely atomized water is realized with the formation of water fog, in this case the nozzles spray cones are oriented mainly in horizontal plane and the spray cones of the lower nozzles cover the room bottom. It results in formation of water fog cloud performing reciprocation in vertical direction of continuously increasing concentration which extinguishes fire effectively with small water consumption regardless of fire location.

Description

Title: Method of fire fighting in the room

Technical Field

The proposed invention relates to the field of fire fighting and can be used in stationary systems of fire fighting in closed rooms, for example, at industrial enterprises, trans- port facilities.

Background Art

The major problem which had to be solved when creating systems of fire fighting in the room is connected with minimization of water consumption and extinguishing time because big water consumption and considerable extinguishing time lead to the equip- ment damage being in the room and to the room itself. The problem becomes more complicated because of the fact that the fire seat may be in arbitrary place and statio¬ nary systems used as a rule for fire fighting in the room are not suitable for selective fire action.

Systems using finely atomized water are the most efficient for fire fighting in the room. It is known from "Physical and Chemical bases of the development and extinguishing of fires", 1980, pp. 182-187 by I. Abduragumov, V. Govorov and V. Makarov that when delivering finely atomized fire extinguishing liquid in the fire seat the efficiency of fire fighting is increased sufficiently in comparison with the use of solid or largely dispersed jets. In this case the efficiency increase of fire fighting is connected with the fact that the processes of heat exchange between small drops of liquid and fire seat are intensified. It leads to rapid temperature decrease in the fire seat up to the flame ex¬ tinction temperature and as a consequence to less consumption of fire extinguishing liquid. The most efficient extinguishing is achieved with the help of water fog the droplets size of which does not increase 50/xm. It is known from "Influence of i I AB and mineral salts additions on fog concentration in the protected room. Prevention and fire fighting on ships. Proceedings. M. 1990" by E. Antyshev, V Bogdanov and V. Terpigorev that if to create water fog in the room round the fire seat than due to natural convection it is drawn into the extinguishing area and under very high concen¬ tration - about 0.3 kg/m³ extinguishes fire very efficiently, that is very quickly and with minimum water consumption. The major problems of formation of high concentra- tion water fog are connected with two phenomena: coalescence - enlargement of fog droplets due to their adhesion and sedimentation - deposition of fog droplets on walls and equipment being in the room. One of the ways of fighting with coalescence is interruption of water fog delivery for some time. During the pause because of different precipitation speed of large and small drops the large drops have time to precipitate from the water fog cloud on the floor. It leads to the fact that during further delivery of water fog their influence on the process of small droplets adhesion becomes less. Optimal pause time is determined experimentally - about 20 - 30 sec. However it signi¬ ficantly increases the total time of fire fighting which leads to more material damage.

Method of fire fighting in the rooms is known from international publication No. WO94/08659 which is characterized by the fact that the fire on the first stage is extin¬ guished with the help of finely atomized water scattering with water fog formation hav¬ ing comparatively large droplets with good penetrative ability in order at least to suppress the fire and later on the second stage originally formed water fog is scattered by the compressed non-combustible gas, including gas lighter than air, in order the fog hit into the upper part of the room which results in formation of turbulent flows of water fog spreading in the whole volume. Such method is good for extinguishing smouldering fire seats however it fails to extinguish high-power fire because higher concentration of water fog is required and in the known method gas delivery for fog scattering prevents obtaining of high fog concentration.

International publication No. WO92/22353 also discloses a method of fire fighting, particularly in engine and similar rooms characterized by the fact that at first water fog is formed intensively under high pressure which is then turbulently scattered in the room due to pressure decrease. High pressure makes for high fog concentration but effective extinguishing is provided mainly in the zone of direct fog hit on the primary stage of method realization. Concentration of further scattered fog that reached the fire seat outside the mentioned zone will be sufficiently smaller which will result in reliability of this method of fire fighting as a whole.

The most close to the proposed invention is the method realized by the installation for fire fighting disclosed in international publication No. WO94/08659. The installation has upper and lower group of nozzles for delivery of finely atomized water situated in the upper part of the room (over the protected object) and In the lower part of the room (at the lower level of the object) correspondingly as well as a group of nozzles at the middle level of the protected object. The spray cones of the upper group nozzles are directed down - directly on the object and the spray cones of the lower group are ori- ented mainly in the horizontal plane towards each other. The nozzles situated at the middle level of the protected object are oriented similarly to the latter. The delivery of finely atomized water is realized by all nozzles simultaneously due to what dense water fog is formed which is concentrated in the room of the protected equipment. This method is rather efficient for fire suppression but it requires big water consumption. Furthermore, the extinguishing reliability of the fire seats situated at a considerable distance from the protected object decreases sufficiently because the entire fog is concentrated round this object.

Disclosure of the Invention

The technical problem toward solution of which the proposed invention is aimed is the creation of fire fighting method in the room using water fog, realization of which requires small water consumption and high reliability of extinguishing is provided regardless of fire seat location.

The essence of the proposed invention is in the fact that in the known method of fire fighting in the room where the delivery of finely atomized water is realized with the formation of water fog with the help of upper and lower group of nozzles, the latter has spray cones oriented mainly in horizontal plane of the room, the delivery of finely atomized water in upper and lower zones is realized in turn. In this case the groups of nozzles are switched after penetration of formed layer of water fog in the action zone of non- working at that moment nozzles groups.

The following technical result is achieved. When switching upper (or lower) group of nozzles the water fog cloud is being formed which begins to travel towards non-work¬ ing at that time nozzles under a pressure of coming from the nozzles gas. Large fog drops (more than 50 m) due to their own weight go down and smaller drops due to the effect of hovering are moved with the speed of about from 0.3 to 8 m/sec under the action of positive pressure formed by the working nozzles. Thus the formed water fog cloud will consist mainly from small droplets. The water fog cloud being formed reaches the opposite non-working nozzles as it goes up or down (depending on what group of nozzles works) after which the groups of nozzles are switched over. The water fog cloud under the influence of positive pressure starts to travel in opposite direction continuing to saturate with small droplets. The process repeats till con¬ centration does not achieve the value under which fire fighting will occur, that is so-called "fire fighting concentration". To achieve high fog concentration is possible due to formation of conditions for long life time of small droplets. The in turn opera¬ tion of the nozzles allows them to fall out on the room surface and on the equipment that is the phenomenon of sedimentation decreases sharply. The process of droplets co¬ alescence (adhesion) also becomes slower because large drops being the main centre of coalescence constantly fall out of the formed fog cloud. Simultaneously the men- tioned character of cloud movement leads to the fact that the cloud spreading laterally overlaps the protected room in horizontal section plate which allows to extinguish the fire seats regardless of their location in the room including outside the zone of direct hit of fog-like water flowing from the nozzles.

Additionally in order to reduce the movement speed of fog cloud down (towards the floor) the nozzles of the upper group are installed in such a way that their spray cones are oriented mainly in horizontal plane. In this case for formation of more even on concentration cloud the spray cones of these nozzles are oriented mainly towards the middle part of the room.

Similarly, to form more even on concentration cloud the spray cones of the lower group can be oriented mainly towards the middle part of the room. Additionally for better "flowing" of fog cloud into the corners of the lower part of the protected room the spray cones of the lower group of nozzles are oriented so that they capture the bottom of the room (floor).

Fire fighting by the proposed method is better to start with the switching on of the upper group of nozzles because fallen at once large drops of finely atomized water begin to participate in the extinguishing reducing the fire seat temperature. Besides, in this case there is the highest probability of direct fall of finely atomized water from the upper nozzles directly on the fire at which also shortens the fire extinguishing time.

Brief Description of the Drawings

The invention is described in greater detail in the following with reference to the particularly preferred embodiments and accompanying drawings, in which

Fig. l represents lay-out diagram and operation of nozzles in the protected room (front view and view from above). In the closed room 1 where the equipment 2 is installed the upper group of nozzles 3 and the lower group of nozzles 4 are installed. The spray cones of nozzles 2 and 3 are also shown in Fig. 1.

Figs. 2-4 show the sequence of formation and movement of water fog in the protected room. The fog begins to form under the operation of nozzles 3 of the upper group (confer Fig. 2). The arrows show the movement direction of water fog cloud 5. When the cloud 5 reaches the action zone of nozzles 4 of the lower group (confer Fig. 3) the latter are switched on and the nozzles 3 are switches off. The cloud 5 continuing to saturate is going up (shown by arrows). When the cloud 5 reaches the action zone of the upper nozzles 3 (confer Fig. 4) the reverse switching over of nozzles 3 and 4 occurs, in the result of which the cloud 5 again begins to go down, its concentration being continuing risen.

Fig. 5 shows the lay-out diagram of the nozzles 6 of fire jet and Fig. 6 - lay-out diagram of the tray 7 with combustible liquid in the carried out ex¬ periment on testing of the proposed method.

Best Mode for Carrying out the Invention

The declared method was carried out on the experimental plant (see Figs. 5 and 6) representing the room 1 with the length L = 5600 mm, width W = 3600 mm and height H = 3900 mm. Diesel fuel spray cone was used as a fire seat. It was fed through the nozzle 6 (see Fig. 5) under pressure p = 10 bar and tray 7 (confer Fig. 6) with the square of 1 square meter, with diesel fuel. The power of the sprayed by the nozzle 6 cone and fire seat on the tray were 1.0 MWt each. The installation places (location) of the nozzle 6 are shown in Fig. 5 where the number of the experiment and the height of its installation are also indicated. The tray 7 was placed on the floor of the room 1 and the places of its installation as well as the number of experiments are shown in Fig. 6. The pilot installation for fire fighting consisted of 24 nozzles of fine water atomization (in 12 each in upper and lower groups) with specific rate (consumption) q = 7.5 1/min (not shown in Figs. 5 and 6). The operation pressure in each nozzle was maintained equal to p = 6.3 bar.

The experiments were carried out in three operating modes of the installation in order to compare efficiency of the declared method with the known ones:

1) the upper and the lower groups of nozzles worked simultaneously during 30 sec;

2) the upper and the lower groups of nozzles worked simultaneously but with the pause: operation - 10 sec, pause - 20 sec, operation -10 sec.

3) the upper and the lower groups of nozzles worked in turn: upper - 10 sec, lower -10 sec, upper - 10 sec.

Under constant specific consumption of the nozzles and taking into consideration time of their operation water consumption was: for the first mode - 90 1, for the second 60 1, for the third - 45 1. The results of the experiments fulfilled are taken to the table 1 (for the spray cone) and table 2 (for the tray).

The experiments proved the mentioned result - formation of the travelling water fog cloud, concentration of which is increased as the nozzles operate as well as high reliability of fire seats fighting regardless of their location at a low total water con¬ sumption. For the realization of the proposed method one can use gas-liquid nozzles, for example, as disclosed in USSR Inventor's certificate No 1316713, published Bl 1987, No. 22 providing fine atomization of water with the formation of water fog.

Table 1

Table 2

Claims

1. Method of fire fighting in the room consisting in the fact that with the help of the upper and lower groups of nozzles situated in the upper and lower zones of the room respectively the delivery of finely atomized water is realized with the formation of water fog, in this case the spray cone of the nozzles of the lower group is oriented mainly in horizontal plane of the room, differs by the fact that the delivery of finely atomized water in the upper and lower zones of the room are realized in turn, in this case the nozzles groups are switched over after falling of the formed layer of water fog on the action zone of non-working at that moment groups of nozzles.

2. Method as defined in claim 1 which differs by the fact that the nozzles spray cone of the upper group is oriented mainly in horizontal plane.

3. Method as defined in claim 2 which differs by the fact that the nozzles spray cone of the upper group is oriented mainly towards the middle part of the room.

4. Method as defined in claim 1 which differs by the fact that spray cone of the lower group of nozzles is oriented mainly towards the middle part of the room.

5. Method as defined in claim 4 which differs by the fact that the spray cone of the lower group of nozzles covers the bottom of the room.

6. Method as defined in claim 1 which differs by the fact that the delivery of finely atomized water begins in the upper zone of the room.