RU2415688C1 - Method of obtaining finely dispersed water and device for its realisation - Google Patents

Abstract

FIELD: fire-extinguishing means.

SUBSTANCE: invention is intended for extinguishing fires with dispersed water and can be used for dispersing liquids for technological aims in order to cover great areas with liquid with its even distribution on the area. Method lies in formation of dispersed water jet from disperser nozzle, water jet, flowing from disperser nozzle is broken in layers into film flows by means of device plates in order to create flow of finely dispersed water, after which said film flows are stretched due to increase of each plate surface and under impact of pressure head are broken into drops. Device contains disperser nozzle, frame and plates, rigidly mounted on frame, the first plate from the nozzle is made in form of round ring, the following plates are made in form of truncated cones, whose generatrices are equal to each other and to thickness of the first plate ring. Breaking of water jet in layers into film flows by plate device for creation of finely dispersed water flow makes it possible to obtain wide angle of dispersed water jet opening and, therefore, large area of irrigation with even distribution of water on the area.

EFFECT: stretching of film flows due to increase of the surface area of each plate and breaking water film into drops under impact of pressure head make it possible to increase efficiency of creation of finely dispersed water flow.

2 cl, 2 dwg

Description

The invention relates to fire fighting equipment and is designed to extinguish fires with sprayed water. In addition, the proposed method and device can be used for spraying liquids for technological purposes, where it is required to cover a large area with a liquid with a uniform distribution over the area.

It is known that when creating a droplet flow, large drops of water with a diameter of up to 1.0 mm, having large kinetic energy, expanding, entrain small drops with a diameter of 50-100 microns and, thereby, increase the angle of the torch opening of the jet of sprayed water.

Large drops of water with a diameter of 300 to 600 microns, flying through a flame, do not have time to evaporate and irrigate the surface of solid burning objects (wood, textile fabrics, etc.), cooling the surface of these objects to a temperature below intense pyrophoric decomposition (200 ° C and below) and stop their burning. Drops of 200-300 microns in size, flying in a flame, precipitate soot particles, solid suspensions in the combustion zone, as well as smoke. Drops of 50-150 microns in size quickly lose their speed in a gaseous fire medium, evaporate, forming a cloud of water vapor, reduce the concentration of fuel vapor in a mixture with atmospheric oxygen to a level below the ignition of this mixture and stop burning.

Studies have shown that to extinguish fires of solid substances, water droplets of the size of the order of 300 - 600 microns are most effective.

When burning liquid petroleum products or other flammable liquids, water droplets of 50-150 microns in size are most effective. Thus, at the design stage, the design of the sprayer allows you to choose the optimal degree of dispersion of sprayed water.

Research has established (I.I. Petrov, V.Ch. Reutt. Extinguishing flames of flammable liquids. Moscow. 1961. Printing house of the Ministry of Public Utilities of the RSFSR. Pages 3-143), that for successfully extinguishing a fire with sprayed water, a device To create a stream of finely dispersed water, it must satisfy the following basic requirements:

- cover immediately the entire combustion area;

- evenly distribute the flow of sprayed water over the irrigation area;

- provide the optimal intensity of the sprayed water per unit area of combustion;

- provide the optimal average size of water droplets (the required degree of dispersion).

Of the variety of known methods for spraying liquids and atomizer designs, as shown by fire tests, the screw atomizer developed at VNIIPO in 1957 (I.I. Petrov, V.Ch. Reutt. Extinguishing the flame of combustible liquids most fully meets the above requirements). Moscow, 1961. Printing house of the Ministry of Public Utilities of the RSFSR. Pages 3-143). As the conducted fire tests showed, one screw sprayer extinguished the flame of gasoline in a tank with a burning area of 60 m ² . Therefore, a screw atomizer is selected as a prototype of the proposed method and device.

The main disadvantage of a screw atomizer is the relatively small area of the turn on which the film of water stretched off from the whole jet is stretched, and therefore, to obtain the required degree of dispersion (average droplet size), an increased water pressure in front of the atomizer is required. In addition, the screw atomizer proved to be difficult to manufacture, making mass production difficult.

The inventive method and device for its implementation eliminate these disadvantages.

To do this, in the method for producing finely atomized water, which consists in forming a stream of a sprayed water stream from a nozzle of a sprayer, the stream of water flowing from a nozzle of a sprayer when forming a stream is layered into film streams with plates of a device for creating a stream of finely sprayed water, then these film streams are stretched by increasing the surface area of each plate and under the action of high-speed pressure is crushed into drops.

In a device for creating a stream of finely atomized water containing a spray nozzle, a frame and plates fixed to the frame, the first plate from the nozzle is made in the form of a circular ring, and the subsequent plates are made in the form of a truncated cone, the generatrix of which is made equal to the thickness of the ring of the first plate.

The technical effect realized by the claimed method is determined by the following.

The breakdown of the water stream layer by layer into film streams with trays by a device for creating a stream of finely sprayed water allows to obtain a wide opening angle of the sprayed water stream and, therefore, a large irrigation area with uniform distribution of water over the area.

Stretching the film flows by increasing the surface area of each plate and crushing under the action of high-pressure pressure on the drops, the film of water can increase the efficiency of creating a stream of finely dispersed water, which consists in the following:

- the process of crushing film flows into droplets in the inventive method occurs at a lower cost of kinetic energy due to the preliminary stretching of these flows on plates, compared with the method implemented in the device adopted for the prototype;

- the smaller the thickness of the sheared film stream and the higher the pressure head, the smaller the diameter of water droplets are formed and, therefore, the greater the degree of dispersion of the sprayed jet.

The technical effect realized by the claimed device is determined by the following.

The execution of the first plate in the form of a disk allows you to increase the area irrigated by the sprayer.

The execution of subsequent plates made in the form of truncated cones, the generatrix of which are equal to each other, as well as the thickness of the ring of the first plate, provides a uniform distribution of the sprayed water flow over the irrigated area by uniformly decreasing the solid angle of each subsequent plate.

In addition, this design of the claimed device allows, even at the stage of its design, to determine the specified degree of dispersion of sprayed water, necessary for extinguishing fires of certain types of combustible materials. For example, when extinguishing wood and other solid combustible materials, relatively large drops of water are needed, and finely dispersed water is most effective for extinguishing combustible liquids.

The design of the inventive device also allows you to minimize the negative impact on its work of scale formed in the supply pipelines or solid suspensions in the water stream.

Figure 1 presents a General view (section along the longitudinal axis) of a device for creating a stream of finely atomized water that implements the inventive method; figure 2 is the same with the distribution diagram of the directions of water flows, including film and droplet flows created by the claimed device; figure 3 is a cross section of the device between the chipper and the first plate; figure 4 is a photograph of the layout of a poppet spray.

The device (figure 1) consists of a nozzle 1, through an inlet with a diameter d _{1 of} which water is supplied to the atomizer. On the nozzle is rigidly fixed frame 2, consisting of a chipper 3 and three spokes 4 (figure 3). Plates are mounted on the spokes 4, the first plate 5 made in the form of a flat round disk with a diaphragm hole in the center of the disk with a diameter of d ₂ , and the subsequent plates 6, 7, 8, and 9 are made in the form of a truncated cone, forming L equal to each other, and also the thickness B of the ring of the first plate 5.

Each of the plates 6, 7 and 8 have corresponding calibrated holes in the center — diaphragms d ₃ , d ₄ and d ₅ . All plates 5, 6, 7, 8 and 9 are mounted rigidly on the frame 2 using knitting needles 4 at a certain distance from the end face 10 of the bump 3, and the holes d ₂ , d ₃ , d ₄ and d ₅ must be aligned with the inlet d ₁ while doing the following ratio:

d ₁ > d ₂ ,> d ₃ ,> d ₄ > d ₅ ,

moreover, the diameters of the apertures and the total number of working plates in the spray is determined by a given degree of dispersion of the sprayed water.

The last plate 9 is made with a bottom 11 and a diameter of d ₆ , while the following ratio should be fulfilled:

d ₅ > d ₆ .

The device operates as follows.

When water is supplied through the inlet d _{1 of the} nozzle 1, the first plate 5 cuts off a film from the water jet with a thickness equal to the difference between the diameters d ₁ and d ₂ . All subsequent plates 6, 7 and 8 similarly cut the film from a jet of water with a thickness equal to the difference between the diameters d ₂ , d ₃ , d ₄ and d ₅ (Figure 2).

The rest of the water stream, reaching the bottom 11 of the plate 9, spreads over the surface of the latter in the form of a film stream.

Thus, the device splits the water jet leaving the nozzle 1 layer by layer into film streams with its plates 5, 6, 7, 8, and 9, then these film streams are stretched by increasing the surface area of each plate and, under the action of the velocity head and surface tension forces, are crushed into drops (Figure 2).

When an unstable flow of water occurs at the inlet of the inventive device associated with water hammer, ripple, etc. the fender 3 allows for disruption of the film stream from the plate 5 to return the specified stream to the surface of this plate, which flows around the corresponding film stream.

A similar function, like chipper 3, is performed by the reverse sides of plates 5, 6, 7, and 8 with marked anomalous phenomena during the formation of the corresponding film flows.

Thus, uniform irrigation of a given area of a controlled burning area is carried out. In this case, the smaller the thickness of the water film being cut off and the higher the pressure head, the smaller the diameter of water droplets are formed and, therefore, the finer the degree of dispersion of the sprayed jet.

Choosing the appropriate difference between the diameter d _{1 of the} inlet of the nozzle 1 and the diameters of the subsequent holes - diaphragms d ₃ , d ₄ and d ₅ and the number of plates (Figs. 1 and 2 show an embodiment of the inventive device with five plates), you can get any given the degree of dispersion of the sprayed water jet at a relatively low water pressure (0.6-0.8 MPa) before the nozzle exit.

Approximate calculations show that the proposed sprayer with the diameter of the inlet nozzle 1, for example, d ₁ = 14 mm, with the above pressure can provide a flow rate of about 3.3 l / s. Formed using the inventive device installed at a height of 2.5 m, the drip stream will cover the floor area up to 5 m in diameter with a uniform distribution of the flux density over the area.

This design of the spray can hardly clog the scale in pipes or solid suspensions in a stream of water.

The inventive method of producing finely dispersed water and a device for its implementation can be used in stationary deluge fire extinguishing installations, as well as mobile fire units.

Claims (2)

1. The method of producing finely atomized water, which consists in forming a sprayed water stream from the nozzle of the atomizer, characterized in that the stream of water flowing from the nozzle of the atomizer during the formation of the stream is split layerwise into film streams with plates of a device for creating a stream of finely atomized water, then these film streams are stretched by increasing the surface area of each plate and under the action of high-speed pressure crushed into drops. 2. A device for creating a stream of finely atomized water containing a nozzle of a spray gun, frame and plates fixedly mounted on the frame, characterized in that the first plate from the nozzle is made in the form of a circular ring, and the subsequent plates are made in the form of truncated cones, the generators of which are equal to each other , as well as the thickness of the ring of the first plate.

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