RU2552972C1 - Method of reduction of spill of liquefied natural gas or liquefied hydrocarbon gas using combined air-and-water foam with low and medium expansion ratio (versions) and system for its implementation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method and system of reduction of spill of liquefied natural gas or liquefied hydrocarbon gas comprises the treatment of the surface of liquefied gas by combined air-and-water foam with low and medium expansion ratio based on synthetic hydrocarbon foamer with formation on the surface of liquefied gas of foam layer minimising the concentration of gas above the surface of the foamy layer below the lower concentration limit of flame distribution.

EFFECT: improvement of efficiency of reduction of spilled liquefied hydrocarbon gas and liquefied natural gas, possibility of safe and controlled liquefied gas spill response is provided, the formation and ignition of air-gas mix during liquefied gas spill are prevented.

40 cl, 14 dwg

Description

Technical field

The invention relates to techniques for eliminating accidents, preventing fire and explosion, extinguishing fires of liquefied combustible gases, and can be used in the energy sector, chemical industry, and transport for stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas (LNG) or liquefied petroleum gas (LPG).

State of the art

Methods for liquefying gaseous hydrocarbons were developed more than 70 years ago, the first industrial marine methane carrier for transporting liquefied methane was built in the early 1950s, and the United Kingdom first switched to import liquefied methane as an energy carrier in 1964.

The beginning of the 3rd millennium was marked by the widespread development and large-scale application of cryogenic technologies for liquefying hydrocarbon combustible (LPG) gases (C ₃ H / H ₁₀ propane-butane mixture) and liquefied natural gas (LNG) (CH ₄ methane) and their widespread use in industrial -energy purposes.

For the global energy sector, this greatly simplified the transportation of energy resources in the form of liquefied gases instead of transporting combustible gas, oil, fuel oil, simplified the storage and transportation of large, medium and small quantities of fuel (from stationary and transport tanks of LPG or LNG), from 20-40 liters to marine tankers with tanks of 200,000 m ³ or more!

The total capacity of vessels for LNG transportation increased from 32 million · m ₃ in 2007 to 78 million · m ³ in 2011, that is, almost 2.5 times. From 2007 to 2012, LNG cargo turnover in the world more than doubled by 2015. The number of marine LNG import terminals will also double and reach 130 [1, 2].

Currently, more than 300 large-tonnage vessels plow the world's oceans daily in the world, transporting annually more than 200 billion m ^{3 of} liquefied hydrocarbon combustible gases. This is more than 100 billion tons of liquefied natural gas annually!

Such intensive pumping, transshipment and transportation of millions of tons of fire and explosion hazard cargo in a forcedly liquefied, thermodynamically nonequilibrium, unstable state is inevitably associated with an increased risk of accidents, outflow and spillage of liquefied gas by depressurization of the product and the occurrence of fire and explosion hazard situations.

Industrial large-scale and large-tonnage operations and transportation (both by land and by sea) are carried out with an ever-increasing pace and volume of production, storage and transportation of LPG and LNG.

The Russian government has now set a task for the Russian industry to increase the scale of production and export of liquefied natural gases (LNG) by 5 times over the next 5 years [3].

This tremendous scientific and technological progress in solving the problems of storage and transportation of liquefied energy resources exacerbated the old ones and led to the emergence of completely new problems of ensuring fire and explosion safety of this huge and technically extremely complex energy economy.

At the same time, in the overwhelming majority of official recommendations, it is proposed to use powder and water fire extinguishing methods that are traditional for flammable liquids (flammable liquids) and flammable liquids (GF), but which are inadmissible for extinguishing LPG and LNG fires, without taking into account cardinal, fundamental differences LHG and LNG from LVH-GZh, specific thermophysical and thermodynamic features of LHG and LNG under "normal conditions" Po = 101.3 kPa and To = 20 ° C and the actual scales (dimensions) and accident parameters - one Other volumes of LPG storage tanks increased by 5–10 times, and LNG by 10–15 or more times compared with LVZH-GZH storage and transportation tanks and, accordingly, the probable fire area increased by 10–15 or more times (up to 5– 10 or more thousand square meters!).

At the same time, it is known that LPG and LNG and their vapors are practically insoluble in water, and the heat supplied to the LPG by sprayed water, and even more so with water vapor, intensifies (accelerates and enhances) the evaporation of LPG by contact with them., and that the flame height during combustion of the spilled liquefied gas is 2-2.5 times larger than the average diameter of the burning area, instead of the average diameter of the usual LVH-GZh fires, and the water is not suitable for extinguishing LNG fires because it sharply enhances the evaporation of LNG, according to the authors, 5-10 times more than with film boiling of LNG and in a fire, which leads to volumetric boiling of an explosive nature, as in the boiling and release of some GF in a fire.

For this reason, it is impossible to supply water to extinguish or localize the evaporation zone in case of LHG and LNG accidents, and at a flow rate of Jv. = 1 l / m ^{2 of} sprayed water in the LNG volume, volumetric boiling of liquid methane occurs, since the water density is almost 2.5 times the density of liquid methane (1000/426 = 2.347), heavy water droplets drown in liquid methane.

In Russia’s well-known fire extinguishing technologies, LPG and LNG recommend the use of imported special fluorine-containing film-forming foaming agents that are forbidden for use for fire extinguishing due to environmental hazards, practically around the world, including the USA, Canada, Europe, Asia and Asia Pacific, Australia, etc.

It is also known that the extinguishing area by the best powder extinguishing fire engines, with a maximum second consumption of fire extinguishing powder and a maximum range of a powder jet supply of not more than 30-40 m in calm weather and without taking into account convective air flows around the fire flame and the most convective flow of combustion products over the area fire, lies in the range 25-40 m ^2, and the fire extinguishing powder on the surface of the liquefied gas causes a sharp boil it to spread on the sides of the flame streams of air and to finite result to increased combustion gas.

Known methods for extinguishing fires in liquefied combustible gas storages by creating an environment that does not support combustion, which are considered one of the most effective fire protection methods for liquefied combustible gas storages, since they not only quickly suppress the flame in the tanks, but also prevent an explosion when accumulated in the storage flammable gases and vapors. For volumetric fire extinguishing, substances are used that can spread in the atmosphere of the protected storage and create a fire extinguishing concentration in each of its elements. Inert gases, diluents (CO ₂ , Ar, N ₂ , etc.) are usually used as such.

A known method of extinguishing a fire in a storage with liquefied combustible gas, comprising filling with inert gas (eg, nitrogen) the entire volume of the storage to a concentration excluding the burning of combustible gas [4].

A device for implementing this method is known, which contains inert gas cylinders and a trunk connected to the storage volume on which shutoff valves are installed. When a fire is detected, the shutoff valves include the supply of inert gas from the cylinders to the storage, creating a concentration of combustible gas below its ignition limit [4].

The disadvantage of this technical solution (both the method and the device) is its low efficiency, especially when the combustible gas has wide flammability limits. In this case, large amounts of inert diluent gas are required, and “pumping” the volume (compartment) where the fire occurs, takes a certain amount of time.

Inert gas fire extinguishing capabilities are greatly enhanced by the use of liquefied inert gases. So, for example, in the technical solution [5], the quenching is carried out with chilled nitrogen gasified from liquid. Deep cooling of the diluent gas significantly increases the efficiency of the inert gas suppression method. The latter is due to the fact that the temperature of reacting gases is much more affected by the rate of a chemical reaction than their concentration.

In the device used in [6], when a fire is detected, shutoff valves on the fire line connected to a cryogenic tank filled with liquid nitrogen open. Liquid nitrogen through this line enters the gas-liquid heat exchanger, where it is gasified by the heat of the surrounding air. The cooled nitrogen thus obtained is sent to suppress the flame.

A known method of extinguishing a fire in a volume with tanks with liquefied combustible gas, comprising filling in a volume with a cooled inert gas during a fire, according to which the inert gas is cooled to the liquefied combustible gas before being supplied to the volume where the fire occurs, gasifying it and releasing it into the environment. The fire extinguishing method is implemented in a fire extinguishing system in a volume with tanks with liquefied combustible gas containing an inert gas source located outside the volume and connected to this volume by an inert gas supply line with shut-off valves, into which a gas-liquid heat exchanger located outside the volume is introduced, the liquid is connected to the discharge line to the environment, and the liquid inlet is connected to the liquefied gas supply line, the gas inlet of this heat exchanger is connected to the supply line gas, and its gas output is communicated with the volume. This solution allows you to use the “cold” stored in the liquefied combustible gas, and due to the “deep” cooling of the inert gas that suppresses the fire, significantly reduce its required amount [7]

The use of liquid nitrogen in fire extinguishing systems has the following disadvantages:

- the limited storage time of the cryogenic extinguishing agent (liquid nitrogen) and the need for regular replenishment of its reserves;

- the problematic use of liquid inert gases in vehicles;

- increased explosiveness of cryogenic systems, including storage systems for liquid inert gases. The cryogenic fire and explosion safety system (PVB) in this case itself becomes explosive;

- the comparative complexity of the design of cryogenic systems and the regulation of their maintenance;

- large dimensions of the heat exchanger for gasification of liquid nitrogen, which is associated with the need to have a high nitrogen flow rate at a low (atmospheric) pressure of nitrogen-heating air,

- the possibility of using inert gases mainly in confined spaces and the complexity, and often impossibility, of their use in emergency spills in open, usually cramped spaces, large volumes of liquefied gas during transportation, storage and use.

A device for extinguishing a combustible liquid in a tank, consisting of a generator of low-level foam and a foam tank. The foam generator is made in the form of a housing with a nozzle for supplying a foaming agent solution to the housing and with an opening for supplying air to the housing. The nozzle is multi-jet. In the case of the foam generator there is a mixing chamber, the entrance of which is installed opposite the nozzle, and the outlet is connected to a foam container having an exit for foam into the reservoir in the form of at least two slit-like openings with the possibility of supplying a flat fan-shaped jet with one of them to a combustible liquid in tank, and the other on the inner wall of the tank. Between the exit for foam from the foam tank to the tank and the mixing chamber there is a sealing membrane made with the possibility of destruction during fire extinguishing [8].

The disadvantage of this device is the unreliability of the design, because the explosion of the vapor-air mixture in the tank causes the destruction of the foam tank, which will lead to a significant increase in the time interval between the start of the fire and the elimination of the fire. There is a danger of destruction of the tank and, as a result, spill of combustible products over large areas, their ignition, as well as a high probability of fire in neighboring tanks.

There is a method of protecting tanks with flammable and combustible liquids from explosion and fire by supplying at least two jets of extinguishing agent — low foam, from the injection unit from above to the inside wall of the tank — according to which the extinguishing agent is supplied in horizontal jets along the tank wall in one direction or simultaneously clockwise and counterclockwise, so that the axis of the jets do not intersect, while the extinguishing agent is supplied with a pressure that ensures the formation on the wall a ring of fire extinguishing agent, moreover, as a fire extinguishing substance, foam of low multiplicity or water is used. At the same time, fire extinguishing powder, inert gas, water vapor are additionally used as a fire extinguishing agent, one or several types of fire extinguishing substances are fed into the reservoir [9].

A device for implementing this method, comprising an extinguishing agent input unit with an outlet to the reservoir at one end and with a cap on the other and nozzles for supplying an extinguishing agent, further comprises one or more nozzles for supplying extinguishing agents horizontally mounted on one or two sides of the input unit at an angle selected from the conditions for the direction of the jets of extinguishing agents along the wall of the tank; the axis of the nozzles mounted on opposite sides of the input node are located in parallel horizontal planes; the input node is made of material with strength characteristics exceeding the strength characteristics of the upper belt of the tank, and the roof of the tank, the cover of the input node and its fastening to the node are made of material with destructive characteristics below the destructive characteristics of the walls of the input node and the upper belt of the tank. At the same time, foam generators, nozzles for supplying foam, water, fire extinguishing powder, inert gas, water vapor are used as nozzles for supplying extinguishing agents, foam generators and foam nozzles are placed in a housing with an air suction hole, it additionally contains one or more input nodes and the input unit is made in the form of a prism with an isosceles trapezoid at the base, the angle of inclination of the side faces of the prism on which the nozzles are fixed is selected from the condition of the direction of the jets along the tank wall [9].

The disadvantages of this technology is the impossibility of its application to prevent fire (stopping), extinguishing fires and eliminating the consequences of fires of LPG and LNG spills.

The closest in technical essence and achieved technical result (prototype) is the recommendations developed by VNIIPO of the Ministry of Internal Affairs of Russia, the fire department of the GUGPS facilities of the Ministry of Internal Affairs of Russia and the Center for Strategic Studies of Civil Protection of the Ministry of Emergencies of Russia for the fire safety of facilities for storage and processing of liquefied hydrocarbon gases for fire protection of the bunded isothermal tank [10 (prototype)].

The fire protection system of the isothermal tank according to these recommendations includes:

- the use of stationary water irrigation installations and stationary fire monitors for protection against thermal effects during fires of outdoor structures of the LPG storage complex;

- steam or water curtains along the perimeter of the debris to limit the spread of LPG vapors during its spills and leaks by dragging them upwards with sprayed jets of water or water vapor and diluting them with air to concentrations below the LEL, which should turn on immediately after an accident automatically from signaling devices of explosive gas concentrations;

- powder fire extinguishing installations on the basis of dry powders of sodium bicarbonate or potassium bicarbonate for extinguishing LPG flames on isothermal tanks in the places of possible LPG leaks (areas for fitting fittings, valves, site equipment, places for installing shut-off and other valves, pump station);

- automatic stationary foam extinguishing installations for fire protection of the collapse of reservoirs with LPG (quick fire localization and flame reduction due to the foam insulating layer) based on foam generators with increased productivity of high-foam foam with foam multiplicity of 700 - 800 without forced air blowing from the electric fan.

Stationary foam extinguishing installation according to these recommendations includes:

- a system and sensors for detecting and warning of a fire or LPG spill in a bunding;

- device for switching on the water supply system;

- a device for dispensing a foaming agent in a dry pipe line;

- containers with a concentrate of synthetic foaming agent suitable for producing high-level foam;

- foam foam generators installed on the edge of the debris.

To protect the open technological equipment in the bunding (shutoff valves, pipelines, hatches in the tanks), foam generators are placed along the edge of the bunding so that the area of the bunding is filled with high-fold foam with a layer height covering all technological equipment, but not less than 2 m, for 10 min.

The technical disadvantages of the prototype method and the prototype device are its applicability only for small-tonnage stationary LPG storage facilities, since the range of high-foam foam with a multiplicity of 600-700 is usually only about 3 m, which leads to the inefficiency and often the inability to use these solutions when stopping and extinguishing LPG fires and LNG emergency spills of liquefied combustible gases during their transportation, processing and use.

Methods and devices for the effective prevention of fire and explosion (stopping) and extinguishing fires during the liquidation of emergency spills of liquefied natural gas (LNG) or liquefied petroleum gas (LPG) in the scope of the patent search were not identified.

Task and technical result

According to most experts in the field of fire and explosion safety in general, and fire and explosion safety of fuel and energy complexes, in particular, the experience and regulatory support of fire and explosion safety when working with LPG and LNG at present in Russia, especially for emergency situations at transportation and discharge / loading facilities of LPG and LNG Hardly ever.

In addition to the huge scale of the total transportation and the grandiose scale of LNG single storage tanks, there are specific features of this combustible liquid (LPG and LNG) - it is stored almost without pressure (under the minimum pressure of its elastic vapor, of the order of 0.2 atm, excessive in relation to the surrounding atmosphere ), at minus temperature -160 ° C for LNG and - 40-42 ° C for LPG. This creates many technological (engineering, thermophysical, strength) problems of its safe storage and transportation.

Upon evaporation of 1 m ^{3 of} spilled liquefied methane (LNG), more than 600 m ^{3 of} gaseous methane is formed with an initial density of about 1.86 kg / m ³ at an evaporation temperature of -160 ° C. This can lead to the formation of more than 6,000 m ^{3 of the} most dangerous gas-air mixture of stoichiometric composition and about 12,000 m ^{3 of} just a fire and explosion hazardous mixture.

The probability of ignition and the explosion zone of this volume of the combustible mixture depends only on the state of the surrounding atmosphere (air temperature and wind speed above the surface of the spilled LNG or LPG and the moment the source of ignition (ignition) of this gas-air mixture appears.

As Gazprom’s many years of experience has shown, in the event of dangerous situations - gas showings (gas leaks), in 30-40% of cases of such leaks, a source of ignition of sufficient power (more than 1-2 millijoules (energy equivalent to 1/100 of the energy released during combustion) only one match head), in the accumulation zone of an explosive gas-air mixture appeared and led to its ignition, fire or explosion. According to more modern data, as applied to accidents with the LPG and LNG strait, the air-vapor mixtures formed as or otherwise (in the form of a fire or explosion) ignite not in 30-40% of cases, but in 90% of cases [11].

Therefore, the practical solution to the problems of preventing explosion, preventing fire (stopping) and extinguishing fires during emergency spills of liquefied natural gas or liquefied petroleum gas is extremely important.

The technical result obtained by using the invention is to increase the efficiency of stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas (LNG) or liquefied petroleum gas (LHG), hereinafter collectively - "liquefied gas", including:

- ensuring the possibility of safe and controlled neutralization of spills of liquefied gas;

- prevention of the formation and ignition (explosion) of a gas-air mixture of gas and air during spills of liquefied gas;

- prevention of ignition (fire) of spills of liquefied gas;

- Effective stopping and fighting fires of emergency spills of liquefied gas at a distance of 30 to 150 m;

- prevention of ignition and controlled burning of liquefied gas after stopping spills of liquefied gas.

The implementation of the invention

The problem is solved and the required technical result is achieved by the fact that when stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas and liquefied petroleum gas, including treating the surface of the liquefied gas with air-foam, according to the first embodiment of the invention, the surface of the liquefied gas is applied low and medium combined water-air foam based on synthetic hydrocarbon foaming agent, for example Snov synthetic hydrocarbon type foaming agent PO 6TST, with a multiplicity of combined water-air foam of low and medium ratio of from 10 to 70 to form on the surface of the liquefied gas foam layer providing lower gas vapor concentration above the surface of the foam layer below the lower flammability limit.

Combined low and medium-sized water-air foam is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, which consists of a layer of porous ice from 0.5 to 5 mm thick, preferably 1 mm thick, a layer of frozen foam with a thickness of 1 to 5 cm, mainly 3 cm and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm, or with the formation of a foam layer on the surface of the liquefied gas, which consists of successively arranged the surface of the liquefied gas layer of frozen foam with a thickness of 1 to 5 cm, mainly 3 cm, and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm

In this case, the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas:

with a leading rate of formation of the foam layer on the surface of the liquefied gas relative to the averaged ascension rate of the gas stream evaporating from the surface of the liquefied gas,

with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas according to the foaming agent solution,

with a minimum length of its jets for areas up to 200 m ² not less than 18-20 m, for areas from 200 to 800 m ² not less than 40-50 m, and for areas more than 800 m ² not less than 70-80 mi up to 150 m,

for a period of not more than 1-25 seconds after a spill of liquefied gas.

by means of foam generators UKTP “PURGA” produced by NPO SOPOT JSC or by means of foam generators UKTP “PURGA” produced by ZAO NPO SOPOT with an automatic control system.

The problem is solved and the required technical result is also achieved by the fact that when stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas and liquefied hydrocarbon gas, including treating the surface of the liquefied gas with air-foam, according to the second embodiment of the invention on the surface of the liquefied gas apply a combined water-air foam of low and medium multiplicity with the formation of a foam layer on the surface of the liquefied gas of a layer of porous ice successively located on the surface of a liquefied gas, a thickness of 0.5 to 5 mm, preferably 1 mm, a layer of frozen foam with a thickness of 1 to 5 cm, mainly 3 cm and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm.

At the same time, a combined low and medium multipurpose water-based foam based on a synthetic hydrocarbon foaming agent, for example, based on a PO-6TsT synthetic hydrocarbon foaming agent, is applied to the surface of a liquefied gas, with a multiplicity of a combined low and medium multipurpose air-foam, from 10 to 70,

with the formation of a foam layer on the surface of the liquefied gas, providing a decrease in the concentration of gas vapor above the surface of the foam layer below the lower concentration limit of flame propagation,

with a leading rate of formation of the foam layer on the surface of the liquefied gas relative to the averaged ascension rate of the gas stream evaporating from the surface of the liquefied gas,

with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas according to the foaming agent solution,

with a minimum length of its jets for areas up to 200 m ² not less than 18-20 m, for areas from 200 to 800 m ² not less than 40-50 m, and for areas more than 800 m ² not less than 70-80 m up to 150 m,

during the time no more than 1-25 seconds after the spill of liquefied gas,

by means of foam generators UKTP “PURGA” produced by NPO SOPOT JSC or by means of foam generators UKTP “PURGA” produced by ZAO NPO SOPOT with an automatic control system.

The problem is solved and the required technical result is also achieved by the fact that when stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas and liquefied petroleum gas, including treating the surface of the liquefied gas with air-foam, according to the third embodiment of the invention on the surface of the liquefied gas apply a combined water-air foam of low and medium multiplicity with the formation of a foam layer on the surface of the liquefied gas, standing it consists of a layer of frozen foam sequentially located on the surface of a liquefied gas, a thickness of 1 to 5 cm, preferably 3 cm, and a liquid foam layer of a thickness of 10 to 40 cm, mainly 25 cm, which ensures a decrease in the concentration of gas vapor above the surface of the foam layer below the lower concentration limit flame spread.

At the same time, a combined low and medium multipurpose water-based foam based on a synthetic hydrocarbon foaming agent, for example, based on a PO-6TsT synthetic hydrocarbon foaming agent, is applied to the surface of a liquefied gas, with a multiplicity of a combined low and medium multipurpose air-foam, from 10 to 70,

with a leading rate of formation of the foam layer on the surface of the liquefied gas relative to the averaged ascension rate of the gas stream evaporating from the surface of the liquefied gas,

with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas according to the foaming agent solution,

with a minimum length of jets for areas up to 200 m ² not less than 20 m, for areas from 200 to 800 m ² not less than 30 m and up to 50 m,

during the time no more than 1-25 seconds after the spill of liquefied gas,

by means of foam generators UKTP “PURGA” produced by NPO SOPOT JSC or by means of foam generators UKTP “PURGA” produced by ZAO NPO SOPOT with an automatic control system.

The problem is solved and the required technical result is also achieved by the fact that the system for stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas or liquefied hydrocarbon gas with surface treatment of liquefied gas with air-foam, according to the invention is configured to receive and apply to surface of the liquefied gas of combined air-foam low and medium multiplicity based on synthetic hydrocarbon foam sprinkling, for example, based on a synthetic hydrocarbon foaming agent of the PO-6TST type, with a multiplicity of combined low and medium water-air foam from 10 to 70, with the possibility of forming a foam layer on the surface of liquefied gas, which ensures a decrease in the concentration of gas vapor above the surface of the foam layer below the lower concentration limit flame spread.

The system is configured to:

applying to the surface of the liquefied gas a combined air foam of low and medium multiplicity with a leading rate of formation of the foam layer on the surface of the liquefied gas relative to the average ascension rate of the gas stream, evaporating from the surface of the liquefied gas,

forming on the surface of the liquefied gas a foam layer from a layer of porous ice, a layer of frozen foam and a layer of liquid foam, successively arranged on the surface of the liquefied gas,

the formation of a foam layer on the surface of the liquefied gas of a layer of porous ice from 0.5 to 5 mm thick, preferably 1 mm thick, a layer of frozen foam from 1 to 5 cm thick, mainly 3 cm and a liquid foam layer of 10 thick up to 40 cm, mainly 25 cm,

forming a foam layer on the surface of the liquefied gas from a layer of frozen foam and a layer of liquid foam successively arranged on the surface of the liquefied gas,

forming on the surface of the liquefied gas a foam layer of successively arranged on the surface of the liquefied gas layer of frozen foam with a thickness of 1 to 5 cm, mainly 3 cm, a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm,

applying to the surface of the liquefied gas a combined air foam of low and medium multiplicity with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas according to the foaming agent solution,

with a minimum length of jets of combined low and medium water-air foam for areas up to 200 m ² not less than 18-20 m, for areas from 200 to 800 m ² not less than 40-50 m, and for areas more than 800 m ² not less than 70- 80 m

applying to the surface of the liquefied gas a combined air foam of low and medium multiplicity for a period of not more than 1-25 seconds after the spill of the liquefied gas,

applying combined air-foam of low and medium multiplicity to the surface of liquefied gas by means of foam generators UKTP “PURGA” produced by ZAO NPO “SOPOT” or by means of foam generators UKTP “PURGA” manufactured by ZAO NPO SOPOT with an automatic control system.

Brief Description of the Drawings

Photo 1 shows the formation of foam layers on the surface of a liquefied gas and gas flows that evaporate from the surface of a liquefied gas.

On a photo 2 - the composition formed from the surface of the liquefied gas from the foam frozen from below and liquid from above.

In photographs 3, 4 - a liquid layer of foam on top.

On a photo 5 - an experimental stand with a tank

area S = 100 m ² , d = 11.2 m with a perimeter fire and fire extinguishing system for LPG and LNG.

On the photo 6 - filling of the tank of the experimental bench of LPG (liquefied propane).

In photo 7 - free combustion of LPG (liquid propane) on an area of 100 m ² with a flame height H of _flame ≈40 m.

In photo 8 - the beginning of the supply of foam to the surface of the LPG (liquid propane).

In photo 9 - the process of extinguishing LPG (liquid propane) at the 25th second

In photo 10 - the process of extinguishing LPG (liquid propane) at the 45th second.

In photo 11 - the process of eliminating the combustion of LPG (liquid propane) within the tank at 88 seconds.

On the photo 12 - complete cessation of combustion of LPG (liquid propane) over the entire area of the tank

In the photo 13 - the beginning of the process of controlled burning of gas-filled foam after stopping the LPG fire.

In photo 14 - the process of controlled burning of gas-filled foam after 30 minutes.

The implementation of the invention

With all this ambiguity and uncertainty of the initial parameters of the emergency during the outflow or spill of liquefied gas (LNG and / or LHG)), it is possible to distinguish the following emergency situations requiring stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas or liquefied hydrocarbon gas:

- opening (full or partial) collapse of the roof of the tank; outflow or spillage of liquefied petroleum gas:

- low-flow (weak) outflow of liquefied combustible gas from small openings;

- simultaneous release of liquefied combustible gas with subsequent prolonged expiration;

- simultaneous release of a large volume of liquefied combustible gas or its intensive outflow;

- total destruction of the tank, with an almost simultaneous outflow and spill of the entire mass of liquefied combustible gas.

In addition, in emergency situations and the dynamics of their development, it is possible to distinguish the following stages of emergency development:

- the outflow of liquefied combustible gas before ignition of the expiring (spilled) liquefied combustible gas;

- ignition of the gas-air mixture in the kinetic regime of its combustion (deflagration explosion of the gas-air mixture);

- ignition of the evaporating, spilled liquefied combustible gas in the diffusion mode of combustion (fire);

- simultaneous ignition of the resulting gas-air mixture and gas vapors above the surface of the spilled liquefied combustible gas (fire with an explosion).

In addition to the specific situational features of accidents and catastrophes from liquefied combustible gas (LPG and LNG) associated with the occurrence of a fire or explosion, the scale and complexity of such accidents is characterized by significant dimensions of the fire area, as well as the power of the explosion, if it occurs.

In case of low-risk flare during the jet outflow of the gaseous or even liquid phase of the liquefied combustible gas through a small hole of 5-6 mm in size, the local thermal power of the flame of the fire flame will be no more than 150-200 kW, and the flame will be no more than 20-30 cm in diameter and not more than 1-2 meters long (depending on the size and shape of the outflow opening, its level of formation, wind strength, etc.).

Such torches can be extinguished by any type of known fire extinguisher (water, foam, powder and even non-combustible gas) from any type of fire extinguisher.

Large fires with an area of several tens and hundreds of square meters (on land, on water, on a floating or stationary platform, on a loading ramp, etc.) have been difficult and sometimes impossible to extinguish with known fire extinguishing systems.

Therefore, under all scenarios of the development of an emergency caused by the spill or outflow of liquefied combustible gas (except for the option of a sudden explosion of a gas-air mixture at the time of the outflow of liquefied combustible gas), the management of the development of an emergency seems to be the most promising and expedient

The use of the invention makes this quite possible in all the above options and at all stages of emergency situations with the exception of sudden explosions by the proposed use of combined foam of low and medium multiplicity supplied to the stream or to the surface of liquefied combustible gas with high intensity and from foam generators with high second flow rate foaming solution and, accordingly, with a sufficiently large radius of the controlled, (regulated) supply of foam jets into the accident zone with the formation of the surface of the liquefied petroleum gas spill of a combined foam layer of medium multiplicity, which makes it possible to stop the development of a fire and explosion hazard situation during the spill of liquefied petroleum gas and to provide the possibility of a controlled response to the consequences of the spill of liquefied petroleum gas.

As shown by a set of studies and full-scale fire tests conducted by the authors at ZAO NPO SOPOT and at the training grounds of Kirishinefteorgsintez OJSC (KINEF OJSC) during the localization and mitigation of the consequences of accidents with liquefied combustible gas through the use of combined extinguishing systems for the UKTP “PURGA” gifts produced by ZAO NPO SOPOT in most cases, the situation can be controlled for a period of time from 1 to 2 seconds, and kept under control for up to 15 20 minutes or more (depending on the scale and complexity of the accident, the number of ARISING spilled fuel, the area of its spreading, the complexity of the object and other situational circumstances of the accident).

In almost all cases, when using the invention, it is possible to avoid or significantly reduce the danger and power of an explosion, reduce the area of an accident or even prevent its occurrence by reducing the accident to a gradual, fire and explosion safe evaporation of spilled liquefied combustible gas or by organizing a controlled, controlled, slow burning of foam saturated with combustible gas from the surface of a spill of liquefied combustible gas.

The invention is based on the following initial concepts and assumptions about elementary processes over the “free” (or “covered”) surface of spilled liquefied combustible gas (LPG and LNG):

In the equilibrium state, liquefied combustible gases, like all other liquids in nature, are under the pressure of their own vapors (saturated vapor in a “closed” vessel) or under another type of coating of the “mirror of the liquid surface” or under the partial vapor pressure (elastic vapor) with free liquid mirror surface.

The gas-air mixture formed directly above the surface of the liquefied combustible gas is very high in the concentration composition of the fuel vapor, the upper concentration limit of ignition (VKPV) of methane is 15 volume%, and the propane / butane mixture is 9 volume%) and becomes fire and explosion hazard only at some distance from this surface, and only after some, even very small, time.

The practical task of ensuring fire and explosion safety in all situations during these accidents is to monitor and control the concentration of liquefied petroleum gas (LPG and LNG) vapors in the entire space of the accident and for the entire time since the start of the accident by means of a liquefied combustible gas (LPG) spill formed above the surface and LNG) according to the invention of a combined layer of combined water foam of low and medium multiplicity, mainly based on synthetic hydrocarbon foaming agent Consisting of disposed directly on the surface layer of the frozen ice dispensing the combined water-air foam of low and medium ratio and located above the liquid water-air combination of the foam layer low and medium ratio mainly based on a synthetic hydrocarbon foaming agent.

Due to the fact that from the moment of an accident (spill or outflow) of liquefied combustible gas they are always at their ambient temperature much higher than their boiling point, they begin to evaporate intensively.

In this case, the total intensity of liquid evaporation is proportional to the area of their free surface, and when water drops fall on a liquefied gas, the evaporation increases sharply until it boils.

The main idea of the invention for ensuring safety in accidents with liquefied combustible gas (LPG and LNG) is to quickly, practically instantly take under physical control the entire free surface of the expiring or spreading fire and explosion hazardous liquid of liquefied combustible gas from the moment the outflow or spreading process begins, with the use of automatic systems switching on and controlling the process of localization and liquidation of the accident with liquefied combustible gas by accelerated formation of combined with loya combined water-air foam of low and medium multiplicity, mainly based on synthetic hydrocarbon foaming agent.

As a technical technique, a technical way of realizing this idea of neutralizing or stopping dangerous accident factors of this kind, the idea (and the corresponding technical methods have been proposed) of operative covering the entire free surface of a spill of liquefied combustible gas (LPG and LNG) with combined low and medium multiplicity air foam mainly based on a synthetic hydrocarbon foaming agent of a certain multiplicity, with certain parameters and properties, using certain techniques chesky devices, systems and devices.

The parameters, composition and properties of low and medium-sized combined air-foam, mainly based on a synthetic hydrocarbon blowing agent, as well as the modes and methods of its supply, are experimentally determined and justified taking into account the thermodynamic and thermophysical features of its interaction when it is in direct contact with the surface of a liquefied combustible gas spill ( LPG and LNG).

The specificity of the problem solved by the invention is that for all other applications of air-mechanical and even chemical foams to extinguish fires of flammable liquids (LVH) and combustible liquids (GH) and / or even protect them from ignition, a very significant role, and in extinguishing fires of combustible liquids, even the dominant role is played by the process of cooling the surface of the burning liquid from its boiling point, to which its surface warms up already in the first 3-5 minutes of the fire, to a lower temperature (d I embodiment extinguishing flammable liquids (GJ), generally to a temperature below the flash point.

When extinguishing a fire of flammable liquids (LVH), the temperature of the surface layer of the liquid decreases to a temperature below its boiling point.

At the same time, in all cases, the evaporation rate of flammable liquids and GF decreases, the vapor pressure of the elasticity of the burning liquid under the foam layer and their partial pressure decrease. Then the mechanical insulating effect of the foam layer only completes the process of isolating the burning liquid and its vapors from the combustion zone, from the zone of the fire flame, and the combustion of the flammable liquids and liquids stops. So the process of extinguishing fires LVZH and GZH.

The thermophysical picture of the thermal interaction of the contacting media when applying air-mechanical foams to the surface of the SG looks significantly different. The temperature of the air-mechanical foam rarely goes beyond +1 to + 15 ° C. This means that the heat transfer (thermal pressure) from the foam to the LPG is about 30-40 ° C, and for LNG even 150-160 ° C. Therefore, the process of evaporation of liquefied combustible gas (LPG and LNG), due to the heat influx from the foam, when applied, does not decrease, but rather intensifies.

Thus, the process of preventing ignition (stopping) of the process of passage of gas evaporating from the surface of the liquefied gas into the above-heated space, into the zone of possible combustion, is reduced to the processes of sorption, absorption, and retention of the flow of gas evaporating from the surface of the liquefied gas, which according to the invention can be provided foam layer of a certain composition, a certain thickness and a certain structure.

Due to the fact that the process of destruction of liquid foam, even in the absence of a fire above or below it, proceeds continuously, and part of the foaming agent flows down through the foam and enters the surface layer of liquefied combustible gas (LPG and LNG), the process of intensification of their evaporation, for the swelling of the “warm” foaming agent solution continues continuously, but may be limited to the ice layer of the frozen foam located directly on the surface of the liquid fuel spill of the ice layer of the frozen combined air-water oh foam low and medium multiplicity.

It has been experimentally determined and theoretically justified that phase transformations at the interface between foam / LPG and / or foam / LNG (foam / liquefied combustible gas) and the surface layer of liquid substances of liquefied combustibles play a special role in the situation of a spill of liquefied combustible gas (LPG and LNG) gas.

Upon contact of the liquid phase of the foam with the liquid phase of the fuel having a temperature of -162 ° C (for LNG) or -42 ° C (for LHG), the lower layers of the foam freeze, passing into the solid phase of a certain snowy structure. Under the layer of frozen snowy foam, a porous ice substrate begins to form directly on the surface of the spill of liquefied combustible gas.

Depending on the dispersion and multiplicity of the foams used, the physical and chemical nature of the foaming agent solution and the ratio of surface tension forces at the phase boundary, the density, porosity, gas permeability, thermal conductivity and buoyancy of the formed snow-like layer of frozen foam under the protective layer of liquid foam depend on.

Consequently, the heat-insulating and gas-insulating properties of the layered SANDWICH on the surface of the liquefied combustible gas spill: the vapor of the liquefied combustible gas, the ice layer, the layer of frozen foam and the layer of liquid foam or the layer of frozen foam and the layer of liquid foam depend on this most significantly.

Further parameters of the process of evaporation of a combustible substance of liquefied combustible gas and the penetration of gas evaporating from the surface of a liquefied gas into a zone of possible controlled combustion above a foam layer or controlled combustion of a gas-saturated foam (concentration of combustible gas above the foam or gas concentration in the foam) depend on the thermophysical properties an ice layer of frozen foam and the next layer of liquid foam. From their thickness, gas permeability, thermal conductivity, sorption properties of the layer of frozen combined water-air foam of low and medium multiplicity and the layer of liquid combined water-air foam of low and medium multiplicity located above.

The authors' studies and full-scale fire tests showed that expensive imported fluorine-containing film-forming foaming agents are the worst known foaming agents for stopping and extinguishing fires of LPG and LNG, and the most effective are cheap, environmentally friendly synthetic hydrocarbon foaming agents produced in Russia, for example, PO- synthetic hydrocarbon foaming agent 6CT.

It was also experimentally established that as the most foam generating agents of combined foams of low and medium multiplicity with a multiplicity of 10 to 70 for stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas or liquefied petroleum gas LHG and LNG, it is advisable to use combined fire extinguishing installations UKTP “Purga” produced by ZAO NPO “SOPOT”, which supply combined foams of low and medium multiplicity to a distance of up to 150 m [12].

Thus, all the displayed essential features of the invention are in a causal relationship with the technical result obtained from the use of the invention.

The specific parameters for stopping and extinguishing a fire of liquefied natural gas or liquefied hydrocarbon gas with low and medium multiplicity of air foam were determined experimentally and practically verified during field tests, which is confirmed by the attached photographs.

As individual elements and components of the system equipment for implementing the process variants, various technologies and materials known and traditional for fire fighting equipment, structural solutions that are usually used to eliminate accidents, prevent fire and explosion (stopping) and extinguish fires of liquefied combustible gases can be used.

Field tests showed a confident solution to the problem and the achievement of the required technical result, namely, the implementation of the present invention improves the efficiency of the response to emergency spills of liquefied natural gas and liquefied petroleum gas, then together - "liquefied gas", ensuring safe and controlled liquidation of emergency spills of liquefied gas, preventing the formation and ignition (explosion) of the gas-air mixture of gas and air in case of emergency vah liquefied gas, preventing ignition (fire) Avarin spills liquefied gas, cupping and effective extinguishing of fires alarm spill liquefied gas in the region of 30 to 150 m, preventing ignition and controlled burning liquefied gas after cupping and extinguishing Avarin LNG spills.

Given the novelty of the set of essential features, the technical solution of the task, the inventive step and the materiality of all general and particular features of the invention, proven in the section "Prior Art" and "Disclosure of the invention", proven in the section "Implementation and inventions" technical feasibility and industrial applicability of the invention, the solution of the inventive task and the confident achievement of the required technical result when implementing and using the invention, in our opinion, The claimed group of inventions meets all the eligibility requirements for inventions.

The analysis also shows that all the general and particular features of the invention are essential, since each of them is necessary, and all together they are not only sufficient to achieve the purpose of the invention, but also make it possible to realize the invention in an industrial way.

In addition, the analysis of the set of essential features of the invention and the uniform technical result achieved through their use shows the presence of a single inventive concept, close and inextricable connection of the implementation options. This allows you to combine the invention in one application, that is, to provide the requirements of the criterion of unity of invention.

INFORMATION SOURCES

1. Assessment of a potential threat to public interest in connection with the planned deployment of an LNG import terminal in the port of Logn Beach. Prepared by Dr. Jerry Havens, President of Havens Associted, lnc.809 09/14/2005.

2. Lavrinenko G.K., Kopytin A.V. Cryogenic complexes for the production and shipment of LNG, its reception, storage and regasification in the international trade system. G. “Technical Gases” No. 3 of 2010

3. Putin VV Safety of the fuel and energy complex. Ser. Industrial and Fire Safety. SECTION Society. State. Industrial safety is the most important condition for the development of the fuel and energy complex of Russia. No. 1 (3) 2013, p.10.

4. Directory “Fire Safety. Explosion hazard. ” M .: Chemistry 1987, p.134-135, 201-203.

5. RU 2131755. MKI A62C 27/00 - 1999

6. RU 2131755. MKI A62C 27/00 - 1999

7. RU 2256472 MKI A62C 3/02 Publ. 07/20/2005.

8. RU 2232041 MKI A62C 3/06 Publ. 07/10/04

9. RU 2334532 MKI A62C 3/06 Publ. 09/27/2008.

10. "Ensuring fire safety of facilities for storage and processing of liquefied petroleum gases." Recommendations http://files.stroyinf.ru/Data2/1/4293831/4293831044.htm (prototype).

11. Departmental standards for the design of LNG production and storage facilities, isothermal storages and gas stations. 4-51-1-88. February 21, 2013; 5. NPB 107-97

12. Combined fire extinguishing installations UKTP “Purga” produced by NPO SOPOT CJSC http://www.sopot.ru/russian/prod.htm

Claims (40)

1. A method for stopping spills of liquefied natural gas or liquefied petroleum gas, comprising treating the surface of the liquefied gas with air-foam, characterized in that a combined low and medium water-based foam is applied to the surface of the liquefied gas based on synthetic hydrocarbon foaming agent with the formation of a foam layer on the surface of the liquefied gas providing a decrease in gas concentration above the surface of the foam layer below the lower concentration limit is common Iya flame. 2. The method according to p. 1, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with an advance rate of formation of the foam layer on the surface of the liquefied gas relative to the average ascension rate of the gas stream evaporating from the surface of the liquefied gas. 3. The method according to p. 1, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas according to the foaming agent solution. 4. The method according to p. 1, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, consisting of a layer of porous ice, a layer of frozen foam and a layer of consecutively arranged on the surface of the liquefied gas liquid foam. 5. The method according to p. 4, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, consisting of a layer of porous ice sequentially located on the surface of the liquefied gas from 0.5 to 5 mm, mainly 1 mm, a layer of frozen foam with a thickness of 1 to 5 cm, mainly 3 cm, and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm 6. The method according to p. 1, characterized in that the combined air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, consisting of a layer of frozen foam and a layer of liquid foam sequentially located on the surface of the liquefied gas. 7. The method according to p. 6, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, consisting of a layer of frozen foam successively located on the surface of the liquefied gas from 1 to 5 cm thick , mainly 3 cm, and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm 8. The method according to p. 1, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of a liquefied gas with a minimum stream length for areas up to 200 m ² not less than 18-20 m, for areas from 200 to 800 m ² less than 40-50 m, and for areas of more than 800 m ² not less than 70-80 m. 9. The method according to p. 1, characterized in that the combined water foam of low and medium multiplicity is applied to the surface of the liquefied gas for a period of not more than 1-25 seconds after the spill of the liquefied gas. 10. The method according to p. 1, characterized in that the combined water foam of low and medium multiplicity is applied to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by CJSC NPO SOPOT. 11. The method according to p. 1, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by ZAO NPO SOPOT with an automatic control system. 12. A method of stopping spills of liquefied natural gas or liquefied hydrocarbon gas, comprising treating the surface of the liquefied gas with air-foam, characterized in that a combined low and medium water-based foam is applied to the surface of the liquefied gas based on synthetic hydrocarbon foaming agent with the formation of a foam layer on the surface of the liquefied gas consisting of a layer of porous ice successively located on the surface of a liquefied gas, a layer of frozen foam and a layer g by the spit of foam. 13. The method according to p. 12, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, consisting of a layer of porous ice sequentially located on the surface of the liquefied gas from 0.5 to 5 mm, mainly 1 mm, a layer of frozen foam with a thickness of 1 to 5 cm, mainly 3 cm, and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm 14. The method according to p. 12, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, which ensures a decrease in the concentration of gas above the surface of the foam layer below the lower concentration limit of flame propagation. 15. The method according to p. 12, characterized in that the combined water foam of low and medium multiplicity is applied to the surface of the liquefied gas with a leading rate of formation of the foam layer on the surface of the liquefied gas relative to the average ascension rate of the gas stream evaporating from the surface of the liquefied gas. 16. The method according to p. 12, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas according to the foaming agent solution. 17. The method according to p. 12, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of a liquefied gas with a minimum stream length for areas of up to 200 m ² not less than 18-20 m, for areas from 200 to 800 m ² less than 40-50 m, and for areas of more than 800 m ² not less than 70-80 m. 18. The method according to p. 12, characterized in that the combined water foam of low and medium multiplicity is applied to the surface of the liquefied gas for a period of not more than 1-25 seconds after the spill of the liquefied gas. 19. The method according to p. 12, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by CJSC NPO SOPOT. 20. The method according to p. 12, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by ZAO NPO SOPOT with an automatic control system. 21. A method for stopping spills of liquefied natural gas or liquefied hydrocarbon gas, comprising treating the surface of the liquefied gas with air-foam, characterized in that a combined low and medium water-based foam is applied to the surface of the liquefied gas based on synthetic hydrocarbon foaming agent with the formation of a foam layer on the surface of the liquefied gas consisting of a layer of frozen foam and a layer of liquid foam successively arranged on the surface of the liquefied gas. 22. The method according to p. 21, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, consisting of a layer of frozen foam successively located on the surface of the liquefied gas from 1 to 5 cm thick , mainly 3 cm, and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm 23. The method according to p. 21, characterized in that the combined air foam of low and medium multiplicity is applied to the surface of the liquefied gas with the formation of a foam layer on the surface of the liquefied gas, which ensures a decrease in the gas concentration above the surface of the foam layer below the lower concentration limit of flame propagation. 24. The method according to p. 21, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with an advance rate of formation of the foam layer on the surface of the liquefied gas relative to the average ascension rate of the gas flow evaporating from the surface of the liquefied gas. 25. The method according to p. 21, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas according to the foaming agent solution. 26. The method according to p. 21, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of a liquefied gas with a minimum stream length for areas up to 200 m ² not less than 20 m, for areas from 200 to 800 m ² not less than 30 m 27. The method according to p. 21, characterized in that the combined water foam of low and medium multiplicity is applied to the surface of the liquefied gas for a period of not more than 1-25 seconds after the spill of the liquefied gas. 28. The method according to p. 21, characterized in that the combined air-foam of low and medium multiplicity is applied to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by CJSC NPO SOPOT. 29. The method according to p. 21, characterized in that the combined water-air foam of low and medium multiplicity is applied to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by ZAO NPO SOPOT with an automatic control system. 30. System for stopping spills of liquefied natural gas or liquefied petroleum gas with surface treatment of liquefied natural gas with air-foam, characterized in that it is made with the possibility of receiving and applying to the surface of liquefied natural gas a combination of low and medium water-frequency foam based on synthetic hydrocarbon foaming agent with the possibility of forming on the surface of the liquefied gas of the foam layer, providing a decrease in gas concentration above the surface of the foam layer below n lower concentration limit of flame propagation. 31. The system according to p. 30, characterized in that it is capable of applying to the surface of the liquefied gas a combination of low and medium water-air foam with a leading rate of formation of a foam layer on the surface of the liquefied gas relative to the average ascending velocity of the gas flow evaporating from the surface of the liquefied gas. 32. The system according to p. 30, characterized in that it is configured to form a foam layer on the surface of the liquefied gas from a layer of porous ice, a layer of frozen foam and a layer of liquid foam successively arranged on the surface of the liquefied gas. 33. The system according to p. 32, characterized in that it is configured to form a foam layer on the surface of the liquefied gas from a layer of porous ice 0.5 to 5 mm thick, predominantly 1 mm thick, a layer of frozen foam from 1 to 5 cm, mainly 3 cm, and a layer of liquid foam with a thickness of 10 to 40 cm, mainly 25 cm 34. The system according to p. 30, characterized in that it is configured to form a foam layer on the surface of the liquefied gas from a layer of frozen foam and a layer of liquid foam successively arranged on the surface of the liquefied gas. 35. The system according to p. 30, characterized in that it is configured to form a foam layer on the surface of the liquefied gas from a layer of frozen foam successively located on the surface of the liquefied gas from 1 to 5 cm thick, preferably 3 cm, a liquid foam layer from 10 to 40 cm, mainly 25 cm. 36. The system according to p. 30, characterized in that it is capable of applying to the surface of the liquefied gas a combination of low and medium water-air foam with a flow rate of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas foaming agent solution. 37. The system according to p. 30, characterized in that it is capable of applying to the surface of the liquefied gas a combination of low and medium water-pressure foam with a minimum length of jets of low and medium water-pressure combined foam for areas of up to 200 m ^{2 of} at least 18-20 m , for areas from 200 to 800 m ² not less than 40-50 m, and for areas more than 800 m ² not less than 70-80 m. 38. The system according to p. 30, characterized in that it is made with the possibility of applying to the surface of the liquefied gas combined water-air foam of low and medium multiplicity for a time of not more than 1-25 seconds after the spill of liquefied gas. 39. The system according to p. 30, characterized in that it is made with the possibility of applying a combined air-foam of low and medium multiplicity to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by NPO SOPOT. 40. The system according to p. 30, characterized in that it is made with the possibility of applying a combined water-air foam of low and medium multiplicity to the surface of the liquefied gas by means of foam generators UKTP "PURGA" manufactured by ZAO NPO SOPOT with an automatic control system.

Images