RU2308996C2 - All-purpose movable foam-generation plant - Google Patents

Abstract

FIELD: foam generation equipment, particularly devices to be used in different objects, preferably in nuclear-fuel cycle objects.

SUBSTANCE: foam-generation plant comprises tank for water or foam-generation solution storage, electrically driven pump, pipe manifold to connect medium expansion air foam generators (foam generators) and fire-hose barrels, pipelines, hoses and fittings. The plant additionally has low expansion foam (K<20) and high expansion foam (K=200-1000) generators including meshes of two types (standard - flat or gauze - three-dimensional woven one). Valve adapted to smoothly control flow rate of foam-generation solution to be fed in high expansion foam generator at rate of 0.5-10 l/min is installed in pipe manifold. Tank has lid for tank sealing to maintain elevated pressure (up to 6 atm) inside tank.

EFFECT: extended field of application.

2 cl, 3 dwg

Description

The invention relates to a device for generating foam and can be used at various sites, mainly at the facilities of the nuclear fuel cycle for:

- extinguishing various fires, including radiation and nuclear hazards;

- localization of radioactive contamination in the premises of facilities like the Shelter at the Chernobyl nuclear power plant, as well as in the premises of nuclear power plants to be decommissioned;

- impregnation by neutron-absorbing elements of fuel-containing masses resulting from beyond design basis accidents in order to reduce the likelihood of a self-sustaining chain reaction (SCR) of fission of nuclear-dangerous elements in them;

- prevention of dusting on terrain, including radioactive contaminated;

- preparation of soil for decontamination (formation on the surface of coatings 1-2 cm thick with subsequent removal of the soil layer by mechanical methods);

- reduction of aerosol activity in the premises during installation and dismantling operations when decommissioning NPP units;

- prevention of dusting during the opening of burial grounds with solid radioactive waste from enterprises of the Radon type for the purpose of their repetition (compaction);

- improving the level of safety during the pressing of dusty radioactive waste, such as ash, in radioactive waste incineration plants at enterprises such as Radon.

The invention can also be used in the generation of adhesive foams to exterminate certain types of harmful insects, including locusts.

Known stationary installation of air-foam fire extinguishing UVP-400, which is designed to extinguish the ignition of various substances and materials, with the exception of alkali metals and substances, the combustion of which occurs without access of air, as well as fires in electrical installations under voltage. It is a structure consisting of a base, a container (water tank) with overall dimensions (mm) length 1480, width 1020 and height 1780, gear pump NShN-600M, an electric motor, a comb for dispensing solutions or water [1].

In the case when the container is filled with a foaming solution, two hoses with medium-sized foam generators GVP-200 are connected to the comb. At the same time, foam productivity of 300-400 l / s with a multiplicity (K) of 80-100 is ensured.

With the introduction of special additives in some regular general purpose foaming agents, they become effective and safe for extinguishing radiation and nuclear hazardous fires. (RF patent No. 2191200. Foaming composition / Stepanov I.K., Martynov D.A., Stepanov A.I., Stepanova O.I. // BI, No. 2, 2002; Application No. 2005-100908 / 12 of 17.01 .05. Foaming composition for extinguishing radiation and nuclear hazardous fires / Stepanov IK, Stepanov AI, Martynov DA, etc. // FIPS, 2005.)

If there is water in the tank, fire fighting is carried out with PC-50 and PC-70 trunks. The range of the installation depends on the number of sleeves used, but does not exceed 100 meters.

The pressure of the working medium in the installation is created due to the operation of an electrically driven pump, foam is generated only of medium multiplicity with high productivity, which is typical mainly for extinguishing various fires, but does not provide operations that are often necessary at NFC facilities, for example, when impregnated with neutron absorbing elements fuel-containing masses resulting from a beyond design basis accident in order to reduce the likelihood of SCR division occurring in them, where a uniform, dosed flow rate is required.

Taking into account the structural features of UVP-400, it can be stated that it is unsuitable for most of the work with the use of foams for special purposes at NFC facilities, i.e. not universal. The dry weight of the unit is about 432 kg. Stationary installation.

The aim of the invention is to increase the versatility of the installation.

This goal is achieved by the fact that the foam generating installation, which includes a container for water or a foaming solution, a pump with an electric motor, a comb for connecting medium-sized air-foam generators (foam generators) and fire barrels, pipelines, hoses and fittings, is additionally equipped with low-frequency foam generators (K <20) and high-frequency foam (K = 200-1000), working with two types of nets (ordinary - flat or metal fabric - volume weaving), and a valve is installed on the comb, allowing smooth ulirovat rate of the foamable solution vysokokratnoy supplied to the foam generator at a rate of 0,5-10 l / min.

In addition, the tank is equipped with a cap designed to seal it when pressure is created in it up to 6 atm using external sources of compressed air, such as a compressor, or blower, or low-pressure air line up to 6 atm, or a cylinder with compressed air or inert gas (nitrogen, carbon dioxide) high pressure, equipped with a gearbox.

In addition, the installation is mounted on a trolley with dimensions of 1 · 1 m, which will allow it to be delivered to the required elevations of buildings and blocks through technological interfloor openings.

The invention is illustrated by drawings, presented in figures 1-3. Figure 1 shows a General view of the installation in a perspective view, figure 2 is the same side view, figure 3 is the same, a view along aa of figure 2.

A multi-purpose mobile foam generating unit is mounted on a trolley 1 and includes a container 2 with a sealing cover 3; an asynchronous motor 4 connected through a clutch 5 to a centrifugal or gear pump 6, comb 7.

The suction line of the pump 6 is connected to the tank 2 with the valve 8, and the discharge line to the comb 7 through the pipe 9. The comb 7 communicates with the tank 2 by the valve 10. The comb 7 has fittings with valves 11, 12, 13 and 14, ending with ruffles 15, 16, 17 and 18, to which rubber hoses with a fire barrel 19, foam generators of medium 20 and small 21 multiples and a foam generator of high-foam foam 22 can be connected. A counter 23 is installed between valve 14 and ruff 18 for measuring the flow rate through n its fluid.

On the comb there is a pipe 33 with a valve 34, to which a splitter (double) 35 is connected, ending with two connecting heads 36 for connecting fire hoses with a diameter of 51 mm, to which either two PC-50 38 shafts (analogue 19) or two foam generators can be connected type GVP-200 39 (analogue 20).

A pipeline 24 with a valve 25, ending in a fitting, to which a source of compressed air (gas) is connected, is connected to the upper bottom of the tank 2. The pipeline 26, ending with a valve 27 with a ruff 28, is designed to connect the air hose of the foam generator of high foam 22.

Either a flat mesh or a volumetric one (metal fabric) can be installed in high-foam foam generators. An ordinary metal mesh is woven from a wire of the same diameter with different mesh sizes: 0.5 · 0.5 or 1.0 · 1.0 mm. The metal-fabric mesh has a diameter of longitudinal threads of 390 microns, transverse 280 microns, and a maximum clearance between filaments of 240 microns, which is less than the diameter of the filaments themselves. Due to the different thickness of the filaments, the mesh becomes embossed, which increases the effective surface area of the contact of the mixture of the foaming solution with air on the mesh and improves the foaming ability of surfactant solutions by 1.5–2 times.

In the proposed installation, the foam generator developed by VO VNIPIET (St. Petersburg) is used as a high-expansion foam generator 22.

However, to generate foams using some developed foaming compositions, in particular a composition based on saponified tall oil pitch, the foam generator was not effective enough. The proposed change in its design made it possible to increase the multiplicity of the generated foams by two or more times (KNOW-HOW). The foam generator can work in two versions: in the first, the foaming solution is supplied by gravity from a separate container, in the second - by force (under pressure). The proposed installation adopted the second option.

A pressure gauge 29 and a safety valve 30 are installed on the upper bottom, and a pressure gauge 31 is installed on the comb 7. For the convenience of working with the foam generator 22, there is a periscopic stand 32, which allows it to be fixed at various heights.

Depending on the actual situation, the installation can be equipped with another combination of foam generators and fire barrels.

For example, when conducting a dust suppression process on the ground or preparing soil for decontamination, it is advisable to install three foam generators of low or medium multiplicity on comb 7. For the convenience of moving the installation up and down on the trolley 1 made four eye 37.

Installation works as follows. In the initial state, the container 2 is completely filled with water or 80-90% foaming solution, all valves are closed, the hoses are disconnected from the comb 7.

Preparing the installation. She is taken to her place of work. To create pressure on the comb 7, depending on the situation, compressed air (or another gas) or a centrifugal (gear) pump is used.

In the first case, the container 2 is sealed with a cap 3 and a source of compressed air (gas) is connected to the fitting on the pipe 24 — a low-pressure air line, or a compressor, or a cylinder of compressed air equipped with a reducer. Valves 25 and 10 are opened. The pressure is monitored in tank 2 by a pressure gauge 29, in comb 7 - by a pressure gauge 31.

In the second case, open the cover 3 of the tank 2, connect the clutch 5 of the electric motor 4 to the shaft of the pump 6, open the valves 8 and 9. Then, power is supplied to the electric motor 4.

If the foaming solution is not ready, pour the necessary amount of foaming concentrate, water and additives (if necessary) into container 2, open valves 8, 9 and 10, and with closed valves 11, 12, 13 and 14 pump the contents of container 2.

Installation work. The whole complex of works carried out by the installation is carried out using the appropriate foam generator and a foaming solution of the required composition or fire barrel.

After connecting the pressure source, the actions of the installation operator are determined by the nature of the work ahead.

Work with a fire barrel. It is performed in two modes. If firefighting is started at the initial moment and the propagation velocity of the combustion does not exceed 0.07 m / s (only solid materials ignited), it is advisable to use the installation in mode 1. At the same time, PC-50 trunks connected to comb 7 using rubber hoses are used having an inner diameter of 16-18 mm. Fire barrel 19 with its rubber hose must be connected to ruff 15. Open valve 12. Water from comb 7 is fed into the fire barrel through a rubber hose.

Extinguishing a fire is done by supplying a stream of water or spraying water (depending on the structure of the barrel) from the barrel 19 to the source of ignition. It is possible and advisable to recharge the tank 2 with water through the open cover 3 in the case of using pump 6 as a pressure source.

If 4-6% washed-out tall pitch is added to water, then the solution will acquire the adhesive and film-forming properties necessary for fixing (localizing) radioactive contaminants. Using this installation, when using a barrel spraying water, it is possible to process the ceilings of the premises of the emergency unit in order to form polymer protective films on them.

If organic substances burn together with solid materials, then the rate of propagation of combustion on the surface will increase by 10 or more times, therefore, the installation should be used in the second mode, in which the water supply intensity reaches maximum values.

When completing a mobile installation with a gear pump NShN-600M using two PC-50 19 shafts connected to a double 35 using fire hoses with a diameter of 51 mm, the water flow rate can reach 10 l / s.

Work with foam generators of medium and low multiplicity. Mode 1. Foam generators 20 and 21 with hoses are connected to ruffs 16 and 17, valves 12 and 13 are opened. The pressure in the comb 7 gives the foam-forming solution through the hoses to the foam generators 20 and 21. The foam of medium and low multiplicity formed in the foam generators is directed to the source of ignition or to another object to be processed. When extinguishing radiation- or nuclear-hazardous fires, the necessary additives are introduced into the foaming solution.

Depending on the purpose of the work, either 2 foam generators of medium multiplicity 20 can be used, for example, to extinguish a fire, or 2 foam generators of low multiplicity 21 to prevent dusting in open areas or for deep impregnation of soil for the purpose of their subsequent decontamination (removal). In the second case, it is necessary to use low-level foam, because it is heavier and, therefore, will be less exposed to wind and contain more film-forming substance necessary for the formation of a polymer film on the surface.

Mode 2. Two foam generators of the type GVP-200 20 with fire hoses are connected to the connecting heads of the double 36. Open the valve 34, the foaming solution from the comb 7 is fed into the foam generator 20 along the fire hose.

Work with a foam generator of high multiplicity. The solution hose of the generator 22 is connected to the ruff 18, the air hose to the ruff 28. The generator 22 is installed on the stand 32 to the desired height. Valves 14 and 27 are opened and, by manipulating them, create the desired ratio "air flow rate - foaming agent flow rate", obtaining a foam of the necessary multiplicity. Foam is directed to the processed object.

Shutdown. At the end of the work, the hoses are washed and the elements of the foam generating unit are dried. Then it is returned to its original state.

Example 1. The use of a foam generator to isolate molten bitumen from fire. At the Leningrad Specialized Plant "Radon" it was necessary to dismantle the tank (height 6 m, diameter 4.5 m), which was intended to supply "clean" bitumen to the bitumen residue bottling plant. However, the dimensions did not allow to remove the capacity from the building without changing its size, for example, height. Metal cutting had to be done with an acetylene-oxygen flame around the circumference of the tank at about half its height. It should be noted that the inner surface of the tank was covered with a layer of bitumen by 1-2 cm. Previous experience in cutting such equipment indicated that bitumen ignition almost always occurred.

Taking into account the large volume of the container and the possibility of the formation of significant amounts of toxic bitumen combustion products, it was decided to cut the metal on the outer surface by pre-filling the container with about three quarters of fire-fighting foam.

When cutting the container, a high-foam foam generator with a metal-fabric mesh was used, which was lowered to a depth of about a meter in the tank hatch. The foam-forming solution entered the foam generator from the installation, which was located at a distance of 13-15 m from the disassembled container with a flow rate of about 1.5 l / min at a constant air flow rate (P = 4-4.5 atm).

To increase the resistance of the foam obtained from a 6% aqueous solution of PO-1 foaming agent, borax was added to it and generated with a ratio of about 600. With an increase in the content of borax in the solution to 4%, the foam ratio decreased by about 10%, but at the same time there is an increase in foam resistance by more than 3 times. The destruction time of the half layer reached 20-25 minutes, and this was enough for the practical application of this composition.

As expected, with an increase in the length of the perimeter burn-through, the level of foam created inside the container began to decrease due to its contact with the hot metal and due to natural decay. To compensate for foam losses, after 15 minutes from the beginning of the cutting process and until its completion (another 1.5 hours), the foam generator was not turned off, but foam was constantly fed into the container. With this technology, a foam layer 1.5–2 m thick above the metal cutting site did not allow oxygen to flow from the air to the bitumen melted from the inside, thereby preventing its ignition.

As a result of the measures taken, the container was successfully cut into two parts and removed from the building.

Example 2. The use of a foam-generating installation to reduce dustiness of the air with foams. To create an increased and controlled dust content in a given volume, a container (bath) of steel dimensions 2.5 · 1.5 · 1.0 m was used. To increase the volume of the container, racks were installed on the walls and a plastic film 1.5 m high was built up. As a result, the total volume of the enclosed airspace of the test vessel reached 10 m ³ .

The dust concentration inside the test volume was created by blowing air from a compressor filled with dust from the dust collector of a household vacuum cleaner. As practice shows, household dust contains the maximum amount of fine, poorly sedimentable (sedimentation). Dust with sizes from 0.1 microns to several microns and is a carrier of volumetric aerosol activity. To uniformly fill the volume of the tank with dust, the dust bag was purged in several places.

Air dustiness (mg / m ³ ) was determined by aspirating air through a portable Typhoon-B sampler with AFA-RMP-20 analytical aerosol filters installed in it. Air sampling was carried out according to the instructions of LSC "Radon".

Sampling and determination of dust content was carried out before the experiment (background value), after blowing dust (initial value), and after cleaning the air with foam. The mass of dust in a unit volume was determined by weighing the filters before and after air aspiration on an analytical balance of the VLR-200 brand with a sensitivity of ± 0.2 mg.

To increase the reliability of the test results, measurements to determine the volumetric concentration of dust at various stages of the experiment (background value, forced dusting, air cleaning with foam) were carried out while pumping various volumes of air (from 1.0 to 5 m ³ ) on different days of the week. The results were averaged over an array of at least 5 measurements.

Dusty air was cleaned by filling the entire volume of the test container with foam obtained from the foam generator of high-level foam. As a foaming solution, a 5% aqueous solution of PO-1 and a 15% aqueous solution of OTP were used. Foam with a multiplicity of 700-800 was obtained at the same flow rates of the solution and air, feeding it into the test container from the top point. After complete destruction of the foam, 2-3 m ^{3 of} purified air was aspirated from the tank and the residual dust content was determined in it.

Test results. The initial background dust content in the air of the test vessel and the test bench averaged over time and over an array of five measurements by volume (from 1 to 5 m ³ ) was 0.8-1.0 mg / m ³ .

The average value of the concentration of dust in the test volume after forced dusting after 15 minutes (taking into account 10 minutes of aspiration) was 80 ± 10 mg / m ³ .

Due to spontaneous sedimentation of dust under the influence of gravitational forces (sedimentation), 1 hour after spraying, the dust concentration in the volume decreased to 10-15 mg / m ³ .

The dust concentration in the test vessel, measured after filling the volume with foam (10 min) and after its complete destruction (40 min), for the OTP solution was the background values of 0.8-1.0 mg / m ³ .

Therefore, the coefficient of air purification reached almost 100%. It was not possible to fill the test chamber with foam generated from PO-1 solution by more than 2/3 of the chamber height.

The source of information

1. Installation of air-foam fire extinguishing UVP-400. (Passport instruction). Office of the Republican Voluntary Fire Society. Chernihiv special enterprise "Pozhtekhnika", 1994.

Claims (2)

1. A mobile multi-purpose foam generator, including a container for water or a foaming solution, a pump with an electric motor, a comb for connecting medium-sized foam generators and fire barrels, pipelines, hoses, fittings, characterized in that the installation additionally contains low-foam and high-foam foam generators, there is a valve on the comb for supplying a foaming solution to the foam generator of high-level foam with a flow rate of 0.5-10 l / min, and the container is equipped with a sealing th cap. 2. Installation according to claim 1, characterized in that it is mounted on a trolley.

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