RU2370292C2 - Method of fire extinction indoors and device for method implementation - Google Patents

Abstract

FIELD: fire safety.

SUBSTANCE: invention involves even water dispersion over the whole room space, spraying walls and all objects present, with further impulse water feed is performed at the beginning of next fire activation. Amount of fluid and duration of impulse feed is defined by given approximate ratios. Device for method implementation includes vessel with fire-extinguishing fluid made of two chambers, one chamber set above the other, with hydraulic connection to reverse valve, L-shaped flow pipeline with sprayer, sprayer perforations spaced apart by distance exceeding room depth. Device features additional chamber with powerful two-position valve, one position of which corresponds to dynamic gas link to high pressure source, the other position establishing dynamic gas link to lower chamber.

EFFECT: lowered temperature indoors, leading to reduced spatial and surfacial irradiation sustaining flame, and utilisation of cooling effect of fresh air in the pauses between impulse fluid feed.

3 cl, 6 dwg

Description

The invention relates to fire fighting equipment and can be used to extinguish fires in residential and industrial premises, including to extinguish developed (intense) fires in them.

A known method of extinguishing a fire, which consists in supplying a compact jet of water to burning objects with the subsequent transition in the final stages of the process to supply water in a sprayed form [1].

The disadvantage of this method is the need to use a large amount of water and the inefficiency of its implementation in fires on large combustion surfaces. In such cases, the jet flow of water to a part of the combustion surface, although it leads to a local cessation of combustion, however, the remaining part of the surface covered by the fire continues to flare up.

The closest in technical essence seems to be a fire extinguishing method proposed in [2]. A known method of extinguishing a fire is the intermittent supply of a jet of extinguishing liquid into the fire. Moreover, for finer atomization of the liquid during unsteady supply, the suction of ambient air or inert gas is provided, and during a pause, the gas-liquid mixture is prepared for subsequent supply by compression to the maximum hydrostatic pressure close to the pressure in the pipeline.

The disadvantage of this method is the inefficiency of its implementation in fires on large combustion surfaces. This is due to the fact that the feed is carried out in small portions, insufficient for the general, at least temporary, termination or weakening of combustion. In such conditions, short pauses in the fluid supply, due to the technological features of the device and not having feedback from the conditions in the burning room, are not effective enough, since the cooling effect of the fresh air that is sucked in is not used enough. In this regard, the total fluid flow rate is quite large.

Known sprinkler installations, which are equipped with premises with increased fire hazard [3]. The sprinkler installation consists of a water source, water supplies, a non-return valve, a control and start-up unit and distribution pipelines on which sprinkler sprinklers and signaling devices are installed. The inclusion of the sprinkler installation occurs automatically in the event of a fire and the operation of the fusible lock. When the sprinkler system is operating, the entire occupied area is irrigated and water curtains can be created.

The disadvantage of the sprinkler system is the lack of mobility, i.e. the possibility of fire extinguishing only in equipped rooms, and insufficiently efficient use of water, requiring high costs.

The closest in technical essence and the achieved effect seems to be fire extinguishing installations with high-pressure finely sprayed water [4]. The installation comprises a water tank, a power unit from a water pump and a drive, a fire hose and a barrel for supplying finely sprayed water. Installations are intended for embedding in fire engines as an additional fire extinguishing means and can be mounted in fire and rescue first aid vehicles. When using the installation, finely atomized water evaporates intensively, while the protective layer of steam isolates the combustion zone. This leads to a decrease in oxygen concentration in the fire and contributes to the cessation of the latter.

A disadvantage of the known installation is the locality of the effect of sprayed water, limited by the space of the fire. In a developed fire, during the decay of the fire source in one place, a new (or repeated) fire occurs in another. In this regard, the use of the installation is most effective, as the authors themselves indicate, when extinguishing a fire at the initial stage of combustion.

The task was, with the economical use of water, to increase the fire extinguishing efficiency in the premises, including developed high-intensity fires.

The problem is solved in that in the known method of fire extinguishing in rooms, including the selection of a fire extinguishing drop liquid and its pulsed supply to the fire, mainly in a sprayed form, water is sprayed evenly throughout the volume of the room with irrigation of the walls and all surfaces located in it, moreover subsequent pulse feeds are carried out at the beginning of the next fire activation. The duration of the pulse supply is selected based on the achievement of such a state when the entire room is simultaneously occupied by moving particles of water or steam, and the required amount of liquid in each pulse supply and the time of the pulse supply are determined from approximate ratios:

m> W / w,

τ> L / ν,

where m is the mass of water in one pulse supply, kg;

W is the capacity of the room, m ³ ;

w is the specific steam capacity for water of approximately 1.7 m ³ / kg;

τ — time of pulsed fluid supply, s;

L is the distance from the spray to the most remote point in the room, m;

ν is the linear velocity of fluid outflow from the atomizer, m / s.

The problem is also solved by the fact that in a known installation containing a vessel with a quenching liquid, an associated flow line with a spray and a high pressure source, the vessel with a fire extinguishing liquid is made of two chambers located one above the other having hydraulic communication with a check valve, when this is connected to the hole near the bottom of the lower chamber made L-shaped flow line, the upper horizontal part of which is installed at the level of the upper edge of the upper chamber, and the sprayer is made in de lateral perforation along the end of the pipeline at a distance greater than the depth of the room, while the lower chamber is also connected to the source of compressed gas by a pipeline, in the gap of which an additional chamber is provided, inside which there is a two-position valve, in one position providing gas-dynamic communication with the gas source, and in another position is the gas-dynamic connection with the lower chamber. As a source of high pressure, a controlled solid fuel gas generator or a compressed gas cylinder can be used.

The implementation of the vessel with a quenching liquid in the form of two chambers located one above the other, having hydraulic connection with a check valve, in combination with the connection of the lower chamber to a high pressure source, allows for the portioned supply of water during its automatic pumping without additional technical means. The installation of an additional chamber in the pipeline rupture, inside which a two-position valve is mounted, in one position providing gas-dynamic communication with the gas source, and in the other position, the gas-dynamic communication with the lower chamber, allows to supply gas at a high flow rate in the presence of even a small flow from the high source itself pressure. The implementation of the flow line G-shaped, the inlet of which is docked to the hole at the bottom of the lower chamber, and the upper horizontal part is set at a level not lower than the liquid level in the upper chamber, eliminates water leakage at the completion of filling the lower chamber. Performing perforation on the upper lateral end of the pipeline at a distance greater than the depth of the room allows you to evenly irrigate the entire volume of the room, helping to lower the temperature of the entire flue gas mixture. The use of a can of compressed gas as a source of high pressure leads to a simplification of the design, and the use of a controlled solid fuel gas generator can significantly increase the supply of compressed gas with constant weight and size characteristics of the device.

The invention is illustrated by drawings, where figure 1 presents a view of the proposed device for implementing the method in section; figure 2 shows a top view of the proposed device; figure 3 shows the position of the two-position and check valves during operation of the device; figure 4 shows a frontal section of the room showing the directions of motion of the torches of sprayed water; figure 5 presents a schematic illustration of the location of the device on the chassis of the car to extinguish a fire in low-rise buildings; 6 schematically shows a device in operation using a crane.

The implementation of the method can be carried out in a variety of conditions. The simplest implementation of the method is achieved using the proposed device. The device (Fig. 1) consists of a tank 1 filled with water, to the bottom of which a working chamber 2 is docked. Between the tank 1 and the working chamber 2 a hydraulic connection is provided in the form of an opening 3, with the possibility of its overlapping by a check valve 4. In the lower part of the working chamber 2 an outlet is provided to which the consumable pipe 5 is docked. The pipe 5 is L-shaped, and in the upper, mainly horizontal part, there are fastening cables 6 and an end nozzle 7 (Fig. 2). The working chamber 2 through a pipeline 8 is gasdynamically connected with a high-pressure source 9. The latter may contain, for example, a solid fuel checker 10, water 11 and a heater 12 with a hermetically-movable gas generation rate regulator 13. An additional chamber 14 is provided in the gap in the pipeline 8. of the chamber 14, a two-position valve 15 is installed, providing in the upper position (Fig. 1) a gas-dynamic connection only with a high pressure source 9, and in the lower position (Fig. 3) - a gas-dynamic connection only with n bottom (working) camera 2.

To fill the tank 1 with water, a hole 16 is made in it, and risers 17 (Figs. 1, 2, 5, 6) are provided for fastening the cables 6, supporting the flow pipe 5 mainly in a horizontal position without unnecessary deflections.

As a source of high pressure can be used a gas generator according to a previously filed application for invention [5], which is depicted in figure 1. (the body of the gas generator is indicated by the number 9). The operation of the gas generator is as follows. When voltage is applied to the glow plug of the heater 12, its bottom part is warmed up, and when the temperature reaches a temperature above the ignition temperature of the fuel, the gas generator is ready for operation. To maintain the combustion process using the rod 13 and the feed mechanism (conventionally shown by multidirectional arrows in the drawing), the heater 12 is pressed against the upper end of the solid fuel checker 10. After ignition of the checker 10, the rod 13 and heater 12 are forced to move down the upper end. At the same time, to stop burning, the heater 12 is stopped or taken up, and the change of ignition, combustion and extinction modes can be carried out repeatedly at arbitrary intervals.

Instead of the described small-sized controlled gas generator as a source of high pressure, it is possible to use more bulky standard cylinders, for example, with compressed nitrogen.

The proposed device can be mounted on a car (figure 5) in the form of a fixed installation, allowing to eliminate fires in one-story buildings. To do this, the car 19 with the installation and the tuned pipeline is adjusted to the burning room, a spray is introduced through the window and pulsed extinguishing liquid is supplied until the combustion is completely or partially stopped.

It is possible to manufacture a portable module (Fig. 6), which is used with a crane 20, which will allow you to extinguish fires in low-rise buildings 21. And to extinguish a fire in high-rise buildings using this module, you can use a helicopter.

To extinguish the fire, the spray gun 7 is introduced into the middle of the room with a contour 18 at the level of the window opening, so that the direction of the spray flames corresponds to the dashed-dotted lines in Fig. 4 by the number of rows of holes (only part of the holes is shown on the spray gun 7).

In such conditions, the operation of the device is as follows. In the initial position, with the hole 3 open, the upper chamber 1, the working chamber 2, and the vertical part of the flow pipe 5 are filled with water. The rod of the on-off valve 15 is in the upper position, so the pressure in the chamber 14 is equal to the pressure in the high-pressure source 9. To supply the quenching fluid to the burning room, the rod of the on-off valve 15 is moved to the lower position (see figure 2), which leads to gas movement from the chamber 14 through the pipe 8 to the working chamber 2. As a result, the check valve 4 closes the hole 3, and the liquid begins to be displaced into the flow pipe 5 and then through the atomizer 7 in a finely dispersed form enter the burning room.

With a pulsed supply of atomized water, fog forms and part of the droplets evaporate. With a developed fire and a small amount of water, the latter can completely turn into steam. All this leads to dilution of the air with agents that do not support combustion. Next, the resulting mixture of steam and drops of water is gradually replaced by new portions of fresh air (due to suction). The incoming air has a temperature of the surrounding atmosphere and therefore in the first periods of time does not support combustion (induction time), but leads to some cooling of the heated combustible materials.

After warming up the incoming air and starting to maintain combustion (visually determined), a second pulse of atomized water is supplied, and the described process is repeated, but deeper cooling is achieved. Subsequent water supply is carried out with increasing time intervals up to "infinity" (complete extinction). With an average fire intensity, 2-3 pulsed feeds are expected. Incomplete fire extinguishing may also be allowed. However, a significant decrease in the temperature in the room will allow people to enter there for final fire extinguishing using manual fire fighting equipment.

As an example, we can calculate the main characteristics of the proposed device in relation to the implementation of the fire extinguishing method in a room having an area of 36 m ² and a volume of 90 m ³ (6 × 6 × 2.5 m). To completely fill such a room with steam, about 60 kg of water must be evaporated. Therefore, according to the proposed method, at least such an amount of water should be contained in one pulse supply. To estimate the parameters, we use the following considerations.

Neglecting the influence of air resistance, we can assume that the water particles flowing out of the hole have a constant horizontal velocity component ν _x and the vertical velocity component changes according to the law of free fall. Then change the vertical coordinate

Hence the time of motion of the particle from the cut of the hole to the floor

During this time, the particles of the jet will travel horizontally distance

Expiration rate

where ρ _w is the density of water, kg / m ³ ;

Δp is the pressure drop between the pressure generated by the gas and the surrounding, Pa;

ψ is the velocity coefficient for water, approximately equal to 0.97.

Substituting (4) in (3), we obtain

Solving (5) with respect to Δp, we obtain

Volumetric and mass flow rates of water are equal

where F _ot is the total cross-sectional area of the holes, m ² ;

f _ot is the cross-sectional area of one hole, m ² ;

N _ot is the number of holes;

µ - coefficient of water flow equal to 0.61 ... 0.65 for a hole in a thin wall.

Water displacement time equals

where M _w is the supply of water in the tank for one cycle.

Considering the process of water displacement isothermal, from the law of conservation of mass of gases and the equation of state of an ideal gas, we obtain

where G _dk is the mass flow of gas from the additional chamber, kg / s;

T _b - gas temperature, K;

R _b - specific gas constant J / (kg · K).

The air supply for one cycle of water displacement is calculated by the formula

The gas pressure p in the water displacement system is estimated as

Assuming the outflow of gases from the additional chamber sound, we can record

where β _k is an indicator characterizing the critical pressure ratio for diatomic gases equal to 0.528.

Using the equation of state of an ideal gas, we find the capacity of the additional chamber

For the initial data: y = 1 m, L _x = 5 m, d _ot = 3 mm, N _ot = 685, we obtain: Δp = 0.065 MPa, ν _x = 11.1 m / s, G _dk = 0.062 kg / s , V _w = 0.033 m ³ / s, G _w = 33.2 kg / s; t _w = M _w / G _w = 1.8 s, M _dk = G _dk t _w = 0.11 kg; V _dk = 32 · 10 ^-3 m ³ .

The gas supply in the cylinder at a temperature T _b = 300 K, a pressure p _b = 15 MPa and a capacity V _b = 40 · 10 ^-3 m ³ is M _b = 6.74 kg.

When using the device in many cycles without reloading the cylinder, the mass of gas remaining in the cylinder and pressure are respectively equal to:

The number of cycles M _bi , kg p _bi , MPa one 3.76 8.37 2 2.08 4.67 3 1.17 2.60 four 0.65 1.45 5 0.36 0.81 6 0.20 0.45

Thus, one fully refilled standard cylinder is enough for 6 cycles of fluid supply.

It should be emphasized the particular advantage of the proposed method and the corresponding device for extinguishing fires in residential and office space on ships. Here, saving water is especially relevant. This is due to the fact that the unused part of the water that accumulates in the premises leads to a loss of stability of the vessel, and therefore there were cases of capsizing. In the present invention, the water flow is minimal.

Information sources

1. Fighting fires on ships. Volume 2. Means of fighting fires on ships / Ed. M.G. Stavitsky. L., Shipbuilding, 1976. P.134.

2. A.s. 1683784 (USSR), cl. A62C 35/00. Fire extinguishing method and device for its implementation / N.T. Moskalenko et al. 07/29/88; publ. 10/15/91, Bull. No. 38.

3. Dobrovolsky A.A. Fire Engineering: A Guide. Kiev: Technics, 1981. P.78-79.

4. Gergel V.I., Tsarichenko S.G. and other Fire extinguishing with finely dispersed water by high-pressure installations for operational use // Fire safety. 2006. No2. S.127-128.

5. Barsukov V.D., Goldaev S.V., Minkova N.P., Polenchuk S.N. A method of controlling the combustion of a unitary solid fuel in a liquid medium and a gas generator // Application for invention. ROSPATENT priority notification, registration number 2006110194 dated 03/29/2006.

Claims (3)

1. The method of fire extinguishing in the premises, including the selection of a fire extinguishing drop liquid and its pulse supply on the surface of burning objects, characterized in that the fire extinguishing liquid is sprayed evenly throughout the volume of the room with irrigation of the walls and all surfaces of the objects located in it, and subsequent pulse deliveries are carried out in the beginning of the next fire activation, and the duration of the pulsed supply is chosen based on the achievement of such a state when the whole room is simultaneously occupied by moving particles of water or steam, wherein the required amount of liquid in each pulse, and supplying the pulsed flow of approximate determined from inequalities:
m> W / w,
τ> L / ν,
where m is the mass of water in one pulse supply, kg;
W is the capacity of the room, m ³ ;
w is the specific steam capacity for water of approximately 1.7 m ³ / kg;
τ — time of pulsed fluid supply, s;
L is the distance from the spray to the most remote point in the room, m;
ν is the linear velocity of fluid outflow from the atomizer, m / s. 2. The fire extinguishing device in the premises, containing the vessel with the extinguishing liquid, the associated flow line with a spray at the end part and a high pressure source, characterized in that the vessel with the extinguishing liquid is made of two chambers located one above the other, having hydraulic communication with the return a valve, while an L-shaped flow line is docked to the hole at the bottom of the lower chamber, the upper horizontal part of which is installed at the level of the upper edge of the upper chamber, and the spray made in the form of upper-side perforation along the end of the pipeline at a distance greater than the depth of the room, while the lower chamber is also connected to a high pressure source through a pipeline, in the gap of which an additional chamber is provided, inside which a two-position valve is installed, in one position providing gas-dynamic communication with a high source pressure, and in another position - gas-dynamic connection with the lower chamber. 3. The device according to claim 2, characterized in that a controlled solid fuel gas generator or a compressed gas cylinder are used as a high pressure source.

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