RU2616290C1 - Method for fire fighting and device for its implementation - Google Patents

Abstract

FIELD: fire safety.

SUBSTANCE: method comprises feeding the water jet to the fire seat in the form of a series-parallel drip flow with the drops radii from 0.5 mm to 1 mm, using a fire extinguishing device, and the choice of the initial size of water drops and the horizontal and vertical distance therebetween is carried out based on the room height. The fire extinguishing device comprises n-extinguishing units, each of which comprises a parallelepiped-shaped housing with projections and grooves made for connecting the modules together in a single structure. In the lower part of the housing, n drop-directing lugs provided with ball check valves are installed in several rows, the upper central part of the body communicating with the hollow metal cylinder equipped with the cover, and the cylinder cavity through the flexible piping equipped with the ball check valve is connected with the water container. A piston with a rubber seal is located Inside the cylinder, wherein the piston rod within the cylinder is equipped with a circular skirt; between the circular skirt and the corresponding projections within the cylinder the spring is installed, and the second rod end protruding from the cylinder through the opening in the cover is coupled with the cam in the opening of which the irreversible electric engine shaft is inserted.

EFFECT: reducing the used extinguishing liquid amount, reducing the fire extinguishing time.

2 cl, 4 dwg, 2 tbl

Description

The invention relates to fire fighting equipment, and in particular to methods and devices for preventing fire or containing fire during fires over large areas, and can be used to eliminate fires at industrial and public facilities.

A known method of extinguishing fires [RU 2396095 C1, IPC A62C 3/00 (2006.01), publ. 08/10/2010] using a flame-retardant aqueous solution of potassium salt, which is fed into the combustion zone as a volume aerosol stream with a particle size range of 5-80 μm with an intensity of at least 0.02 l / (m ² s).

The disadvantage of this method is the insufficient rate of evaporation of the quenching liquid (vaporization) in the flame zone due to the content of combustion inhibitor salts in it. More time is required to lower the flame temperature to the cessation of combustion. Therefore, the consumption of the extinguishing composition increases and, as a result, the total time for eliminating the fire increases. The small size of the liquid particles during the extinguishing of fires, especially the foci of large forest fires, leads to a change in the direction of movement of most of the aerosol stream, its rotation and entrainment into the surrounding atmosphere with ascending combustion products.

A known method of fire extinguishing in rooms [RU 2370292 C2, IPC A62C 3/00 (2006.01), A62C 35/02 (2006.01), A62C 27/00 (2006.01), publ. 10.20.2009], including the selection of extinguishing droplet liquid and its pulse supply on the surface of burning objects. Extinguishing liquid is sprayed evenly throughout the room with irrigation of the walls and all surfaces located in it objects. Subsequent pulsed feeds are carried out at the beginning of the next fire activation, and the duration of the pulsed feed is selected based on the achievement of such a state when the entire room is simultaneously occupied by moving particles of water or steam.

The disadvantage of this method, along with a strong gulf of the entire area of the room with water, is the difficulty of its implementation, associated with the need for prognostic determination of the moment of the next fire activation, as well as the calculation of the spraying time and the mass of water spent during spraying.

A known method of extinguishing fires [SU 1247019 A1, IPC4 A62C 1/06, publ. 07/30/1986], selected as a prototype, which consists in supplying a sprayed stream of water to a fire source, the sprayed jet being created with a dispersion variable with respect to the jet cross section, and feeding to the fire source is carried out with increasing dispersion from the center of the fire source to its periphery.

Variable dispersion of the stream leads to its uneven evaporation in the flame zone of combustion. The final result of such an impact is uniform irrigation of the burning surface with water, which with prolonged exposure leads to a significant consumption of water, as well as to flood the premises. Damage from such exposure can far exceed losses caused by the fire itself.

A device for the formation of one-dimensional drops of liquid or gas bubbles [RU 123516 U1, IPC G01F 11/00 (2006.01), publ. 12/27/2012], containing a reservoir with a liquid or gas and an undeformable capillary attached to it, inside of which there is a rigid, non-touching, pointed core core, the end of which is offset from the end of the capillary. The end of the rigid core can be shifted outward by a distance exceeding the inner diameter of the capillary or inside the capillary by a distance not exceeding the inner diameter of the capillary.

A device for the formation of droplets of uniform sizes [SU 1682 A1, IPC6 B01J 2/02, publ. 09/30/1926], in which the ends of a bent arc of a wire of a smaller diameter than the diameter of the holes used to save the dropping liquid and forming drops at the ends of the wire in advance of a predetermined value are passed through each pair of neighboring outlet openings in the bottom of the vessel.

These devices do not allow the generation of uniformly sized successive drops of liquid with a controlled distance between them, since the distance between the drops in them depends only on the frequency of generation of the drops. With an increase in the generation frequency, the distance between moving droplets decreases, but their size changes substantially.

A known device for producing small single drops of liquid [SU 84581 A1, IPC6 G01N 11/04, publ. 01/01/1950], made in the form of a horizontally located tube with a continuously flowing liquid and a reciprocating rod moving along this axis of the tube, during its movement periodically coming into contact with the meniscus of the liquid in the tube and when it detaches a single drop from the meniscus.

The flight path of a single droplet generated by this device has the form of a parabola, since the droplet detaches from the meniscus with the rod in the horizontal direction, which subsequently, under the action of gravity, leads to its movement along the arc of the parabola. Thus, even the installation of several such devices on top of each other at a fixed distance makes the task of generating sequentially moving drops impossible because of the difficulties in predicting the trajectory of their movement, which depends on the diameters of the rod and tube, as well as the properties of the liquid and its amount in the tube. In addition, to vary the size of the drops, it is necessary to change the diameters of the tube and rod.

A device for dispensing liquid in single drops [RU 73654 U1, IPC B65D 47/18 (2006.01), publ. May 27, 2008], adopted as a prototype, intended for the formation of single periodically repeating drops and containing a dropper with an internal rotary channel and a drop-guiding tip with a vertical axis, connected by a flexible conduit to a liquid vessel connected with a hydrostatic pressure regulation mechanism. The dropper is equipped with a reciprocating vertical movement drive, configured to create a single positive impulse of hydrostatic pressure with amplitude and duration, providing the formation of a tear drop.

The drive of the reciprocating vertical movement is made in the form of a cam mechanism, a spring-loaded plunger of which is rigidly connected to the dropper, and the cam to a non-reversible electric motor.

The disadvantage of this device is the inability to generate sequentially moving droplets with a small distance between them. This is due to the fact that the liquid in the container is at atmospheric pressure, and when lowering the drip tip, it is necessary to wait a certain time so that a drop of liquid can form and break away from the tip.

The objective of the proposed group of inventions is to reduce the amount of water used to extinguish a fire, as well as reducing the time to eliminate it.

In the method, water is supplied to the fire zone in the form of a series-parallel drip stream with radii - R _d drops from 0.5 mm to 1 mm using a fire extinguishing device. The initial size of the water droplets and the distance between them horizontally and vertically are selected based on the height of the room.

The fire extinguishing device contains n-extinguishing modules, each of which contains a drip tip, a vertical reciprocating drive in the form of a cam mechanism, a spring-loaded pusher.

Each of the fire extinguishing n-modules contains a parallelepiped-shaped housing, on two adjacent sides of which protrusions are made, and on the other two sides, grooves. In the lower part of the body, n holes are made in several rows, into which drip-guide tips are installed, equipped with ball check valves. The upper central part of the housing is in communication with a hollow metal cylinder provided with a cover. The cylinder cavity through a flexible pipe equipped with a ball check valve connected to the tank with water. A piston with a rubber seal is located inside the cylinder. The piston rod inside the cylinder is equipped with a circular skirt. A spring is installed between the circular skirt and the corresponding protrusions inside the cylinder. The second end of the stem protruding from the cylinder through an opening in the cap is mated to a cam. A shaft of a non-reversible electric motor is inserted into the cam bore.

The proposed use of n-modules of fire extinguishing allows the generation of a series-parallel drip stream that completely evaporates when passing through high-temperature combustion products and a flame zone of combustion. The results of experimental and theoretical studies show that for the optimal (most efficient) use of water when extinguishing fires, it is necessary to ensure that the droplets completely evaporate during the passage of the flame and high-temperature combustion products. Due to the intense and complete evaporation of water, the temperature in the fire zone decreases, and the steam cloud formed as a result of evaporation gradually fills the entire volume of the room and displaces the oxidizer (oxygen) from the fire zone. This causes the fire to die out.

Using the approach to assessing the degree of evaporation of water given in the article “Strizhak P.A. The effect of the distribution of droplets in a "water projectile" on the temperature and concentration of combustion products in its wake // Engineering Physics Journal. 2013.Vol. 86, No. 4. S. 839-848 ”, a mathematical model was compiled, with the help of which it was possible to determine the optimal distance between the drops of water at which they will completely evaporate over the entire flame height. So, in particular, it is advisable to withstand distances between parallel moving droplets from 2R _d to 3R _d , and between successively moving droplets from 5R _d to 7R _d . At such distances between the droplets, it is possible to minimize the likelihood of their coalescence or fragmentation, and also to reduce the influence on the evaporation conditions of neighboring droplets, thereby increasing the temperature in the vicinity of the droplets and the rate of their evaporation. Using this approach, it is possible to predict the optimal droplet size and the distance between them to fill the combustion zones of different sizes with water vapor, and, as a result, to achieve maximum fire fighting efficiency.

Thus, the supply of water to the fire zone in the form of a series-parallel drip flow reduces the amount of water used to extinguish and reduce the time to eliminate the fire.

Table 1 shows the values of the radii of water droplets (according to the results of experimental studies), at which the droplets are able to completely evaporate during the movement of high-temperature (1100 K) combustion products in the stream (when droplets travel different distances).

Table 2 shows the volumes of water sufficient to completely fill the room with a steam cloud for different sizes of rooms.

In FIG. 1 shows a fire extinguishing module before droplet generation.

In FIG. 2 shows a bottom view of the proposed fire extinguishing module.

In FIG. 3 shows a fire extinguishing module after droplet generation.

In FIG. 4 shows an example of a fire extinguishing device consisting of nine fire extinguishing modules.

The device for extinguishing fires contains n-extinguishing modules. The modules are interconnected by means of grooves and corresponding protrusions made at the ends of their bodies.

Each fire extinguishing module (Fig. 1) contains a box 1 in the form of a parallelepiped, on two adjacent sides of which protrusions are made, on the other two sides - grooves, by means of which the modules are connected together in a single structure. In the lower part of the housing 1, n holes are made in several rows (Fig. 2), in which drip guides 2 are installed, equipped with ball check valves 3. The upper central part of the housing 1 is in communication with a hollow metal cylinder 4 provided with a cover 5. The cavity of the cylinder 4 through a flexible conduit 6 provided with a ball check valve 7 is connected to a container with water (not shown). Inside the cylinder 4 is a piston 8 with a rubber seal 9. The rod 10 of the piston 8 inside the cylinder is equipped with a circular skirt. A spring 11 is installed between the circular skirt and the corresponding protrusions inside the cylinder. The second end of the rod 10 protruding from the cylinder 4 through the hole in the cover 5 is connected to the cam 12. A shaft of a non-reversible electric motor (not shown) is inserted into the cam bore 12.

Water is supplied to the device through a flexible pipe 6 connected to a container with water under pressure. Using the shaft of the electric motor, the cam 12 is rotated. The rod 10 with the piston 8 fixed on it moves down, compressing the spring 11. In parallel with this, water is squeezed out of the internal cavities of the tank 1 and the hollow cylinder 4 by the piston 8 and the rubber seal 9. At the same time, the reverse ball valve 7, opening the check ball valves 3 in the drip tips 2 and squeezing drops out of them (Fig. 3). Drops of water come off, a further rotation of the cam 12 occurs, the spring 11 opens and the piston 8 moves upward with a rubber seal 9. In this case, the check ball valves 3 in the drop guide tips 2 close and the check ball valve 7 opens, water begins to fill the internal cavities of the tank 1 and hollow cylinder 4. Next, the whole process is repeated.

The proposed method of extinguishing fires is as follows. If a fire is detected, a system is started (automatically or manually) consisting of n proposed fire extinguishing modules. Placed in the upper part of the room (under the ceiling), the devices begin generating a series-parallel drip water flow (Fig. 4). The flow parameters are set at the stage of assembly of the system in such a way that when passing the distance from the ceiling to the lower part of the room, the drip stream completely evaporates (data from table 1 are used). In this case, the steam cloud formed as a result of the evaporation of water droplets gradually fills the entire volume of the room and displaces the oxidizer (oxygen) from the fire zone. The fire is extinguishing. Stop the system.

To automatically turn the system on and off, it can be equipped with a set of heat and smoke sensors, the signal of which will start it and, accordingly, stop it.

Drop generation is carried out at such a speed (the rotation speed of the shaft of a non-reversible electric motor is selected) so that the distance between successively moving drops (rows of such drops) does not exceed 5R _d to 7R _d . In this case, the size of the drops is chosen based on the height of the ceiling of the room, being guided by the data of table 1.

Table 2 shows the characteristic volumes of water (according to the research results) sufficient for the complete evaporation of droplets (initial radii of not more than 0.5 mm) and the formation of a vapor cloud in the combustion zone. When obtaining the data, typical temperature and concentration traces of droplets were taken into account when varying the distances between them. The values of the water volumes shown in Table 2 are calculated for conditions under which drops moving in parallel were removed by 3R _d relative to each other, and successively moving by 5R _d .

Numerical estimates (table 2) show that the application of the proposed method is much more economical than the use of conventional deluge or sprinkler fire extinguishing systems, in which the water flow per irrigator can reach up to 0.5 l / s. In addition, it should be noted that, taking into account the possibility of ensuring different temperatures in the droplet trail, the formation of steam clouds can be organized due to the successive supply of droplets with decreasing (from row to row) initial sizes. In this case, the values of the consumed volumes of water will become even smaller than those presented in table 2. For example, with the size of the first drops R _d = 0.3 mm and the last not more than 0.1 mm, it is possible to decrease the values of the volumes given in table 2 by 15 -25%.

Claims (2)

1. The method of extinguishing fires, which consists in supplying a jet of water to the fire, characterized in that the water is fed into the fire zone in the form of a series-parallel drip stream with droplet radii from 0.5 mm to 1 mm using a fire extinguishing device, and the initial sizes of water droplets and the distance between them horizontally and vertically is based on the height of the room. 2. Fire extinguishing device containing n-extinguishing modules, each of which contains a drip tip, a vertical reciprocating drive in the form of a cam mechanism, a spring-loaded pusher, characterized in that each of the fire extinguishing modules contains a box in the form of a parallelepiped, on two adjacent sides which protrusions are made, on the other two sides - grooves, with which the modules are connected together in a single structure, n about apertures in which drip-guide tips are installed, equipped with ball check valves, the upper central part of the housing communicating with a hollow metal cylinder equipped with a cover, and the cylinder cavity through a flexible pipe equipped with a ball check valve, connected to a container with water, a piston is located inside the cylinder with a rubber seal, while the piston rod inside the cylinder is equipped with a circular skirt, a spring is installed between the circular skirt and the corresponding protrusions inside the cylinder, and ayuschy from the cylinder through a hole in the lid of the second end of the stem is associated with a cam, which is inserted into the hole of the motor shaft irreversibly.

Images