RU2757106C1 - Method for localising spills of liquefied natural gas or liquefied hydrocarbon gas with hybrid foam and system for implementation thereof - Google Patents

Abstract

FIELD: petroleum industry.

SUBSTANCE: group of inventions relates to the technology for eliminating technological and transport accidents in order to prevent fires, explosions, reduce the intensity of combustion and extinguish fires, further - localise, in elimination of the consequences of emergency and technological spills of liquefied natural gas or liquefied hydrocarbon gas, and can be used in power engineering, transport, gas production, gas processing and chemical industry. The method for localising spills of liquefied natural gas or liquefied hydrocarbon gas includes applying a layer of air-and-water foam onto the surface of the spill of liquefied gas. A hybrid air-and-water foam produced as a result of turbulent mixing in the process of cocurrent movement of jets of low-expansion mechanical air foam and medium-expansion mechanical air foam is applied onto the surface of the spill of liquefied gas by means of a system containing means of generating low-expansion mechanical air foam and means of generating medium-expansion mechanical air foam, configured to produce and apply at least one jet of hybrid air-and-water foam produced as a result of turbulent mixing in the process of cocurrent movement of jets of low-expansion mechanical air foam and medium-expansion mechanical air foam onto the surface of the spill of liquefied gas.

EFFECT: improved technology of localizing spills of liquefied natural gas or liquefied hydrocarbon gas with hybrid foam.

27 cl, 13 dwg

Description

Technology area

The invention relates to a technique for eliminating technological and transport accidents to prevent fires, explosions, reduce the intensity of combustion and extinguish fires, then - stopping, in the elimination of the consequences of emergency and technological spills of liquefied natural gas (LNG) or liquefied petroleum gas (LPG), hereinafter together - liquefied gas (LPG), and can be used in power engineering, transport, gas production, gas processing and chemical industries.

State of the art

Methods for liquefying gaseous hydrocarbons were developed more than 80 years ago, the first industrial marine methane carrier for the transportation of liquefied methane was built in the early 50s, and the UK first switched to the use of imported 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 the liquefaction of hydrocarbon combustible (LPG) gases (propane-butane mixture С ₃ Н ₈ / C ₄ H ₁₀ ) and liquefied natural gas (LNG) (methane СН ₄ ) and their wide use for industrial and energy purposes.

For the world energy sector, this greatly simplified the transportation of energy resources in the form of liquefied gases instead of transporting oil and fuel oil, simplified the storage and transportation of large, medium and small amounts of fuel (from stationary and transport LPG or LNG containers), with a volume of 20-40 liters to sea tankers with tanks with a volume of 200,000 m ³ and more.

Total capacity of LNG carriers has increased from 32 million ^m3 in 2007 to 78 million m ³ in 2011, which is almost 2.5 times. From 2007 to 2012, LNG cargo turnover in the world has more than doubled by 2015, the number of sea terminals for LNG imports will also double and reach 130 [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. J. "Industrial gases" No. 3 2010].

At the beginning of 2020, there were about 500 gas tankers in the world, and about 50 were built in 2019, which are capable of transporting about 400 billion cubic meters ^of liquefied hydrocarbon combustible gases annually. This is more than 200 billion tons of liquefied gas annually!

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

Industrial large-scale and large-scale work and transportation (both by land and sea) are carried out with an ever-increasing pace and volume of production, storage and transportation of both 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) 5 times over the next 5 years [V.V. Fuel and energy complex safety. Ser. Industrial and Fire Safety. Sec. Society. State. Industrial safety is the most important condition for the development of the Russian fuel and energy complex. No. 1 (3) 2013 p. ten].

This colossal scientific and technological progress in solving the problems of storage and transportation of liquefied energy resources exacerbated the old and caused the emergence of completely new problems of ensuring the fire and explosion safety of this huge and technically extremely complex energy sector.

At the same time, at present, the overwhelming majority of official recommendations propose the use of powder and water methods of fire extinguishing, traditional for flammable liquids (FL) and combustible liquids (GF), but unacceptable for use in extinguishing LPG and LNG fires, powder and water methods of fire extinguishing, without taking into account the cardinal, fundamental differences of LPG. and LNG from flammable liquids - combustible liquids, specific thermophysical and thermodynamic features of LPG and LNG under "normal conditions" Po = 101.3 kPa and To = 20 ° C and the actual scale (size) and parameters of accidents - unit volumes of LPG storage tanks increased by 5 -10 times, and LNG 10-15 or more times compared to storage and transportation tanks for flammable liquids-GZh and, accordingly, the probable area of the fire increased 10-15 times or more (up to 5-10 and more thousand square meters!) ...

It is known that LPG and LNG and their vapors practically do not dissolve in water, and the heat supplied to LPG by sprayed water, and even more so by water vapor, intensifies (accelerates and enhances) LPG evaporation by 5-10 times in contact with them, and that the height of the flame during the burning of the spilled liquefied gas is 2-2.5 times greater than the average diameter of the combustion area, instead of the usual 0.8-1.2 average diameter for LVZH-GZh fires, and the water is not suitable for extinguishing LNG fires, because ... it sharply enhances the evaporation of LNG, according to the authors' estimates, 5-10 times more than during 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 for extinguishing or localizing the evaporation zone in case of LPG and LNG accidents, and at the rate of supply Jw. = 1 l / m2 ^of sprayed water in the LNG volume, liquid methane volumetric boiling 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 the technologies of LPG and LNG fire extinguishing well-known in Russia, it is recommended to use imported special fluorine-containing film-forming foaming agents, which are prohibited for use in fire extinguishing for reasons of their environmental hazard, practically all over the world, including in the USA, Canada, Europe, and Asian countries. Pacific, Australia, etc.

It is also known that the extinguishing area of the best fire engines of powder extinguishing, with the maximum second consumption of the extinguishing powder and the maximum range of the powder jet no more than 30-40 m in calm weather and without taking into account the convective air flows around the fire flame and the convective flow of combustion products itself over the area fire, lies in the range of 25-40 m ² , and the supply of fire-extinguishing powders to the surface of the liquefied gas leads to its sharp boiling, to the spread of air flows on the sides of the flame, and, ultimately, to intensification of gas combustion.

There are known methods of extinguishing fires in storages of liquefied combustible gases by creating there an environment that does not support combustion, which are considered one of the most effective methods of fire protection for storages of liquefied combustible gases, since they not only quickly suppress flames in containers, but also prevent an explosion when accumulating 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. As such, inert diluent gases (CO ₂ , Ar, N ₂ , etc.) are usually used.

A known method of extinguishing a fire in a storage with liquefied combustible gas, including filling with an inert gas (for example, nitrogen) the entire volume of the storage to a concentration that precludes combustion of combustible gas [4].

Known device for implementing this method, containing cylinders with an inert gas and a line docked to the storage volume, on which shutoff valves are installed. When a fire is detected, shut-off valves turn on the supply of inert gas from cylinders to the storage, creating a concentration of combustible gas there below the limit of its flammability [Reference "Fire Safety. Explosion Hazard". M .: Chemistry 1987, p. 134-135, 201-203].

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 quantities of an inert diluent gas are required, and "pumping" it into the volume (compartment) where the fire occurs takes a certain amount of time.

The possibilities of fire extinguishing with inert gas are significantly expanded when using liquefied inert gases. So, for example, in the technical solution [RU 2131755, MKI A62S 27/00 - 1999], extinguishing is carried out with cooled nitrogen gasified from liquid. Deep cooling of the diluent gas significantly increases the efficiency of the inert gas fire suppression method. The latter is due to the fact that the rate of a chemical reaction is much more strongly influenced by the temperature of the reacting gases than by their concentration.

In the device used in RU 2131755, MKI A62S 27/00 - 1999, when a fire is detected, shut-off valves are opened on the fire main connected to a cryogenic container filled with liquid nitrogen. Liquid nitrogen through this line enters the gas-liquid heat exchanger, where it is gasified due to the heat of the ambient air. The cooled nitrogen obtained in this way is directed to suppress the flame.

There is a known method of extinguishing a fire in a volume with containers with liquefied combustible gas, including filling the volume with a cooled inert gas during a fire, according to which the inert gas is cooled with liquefied combustible gas before being fed into the volume where the fire occurs, while simultaneously gasifying the latter and throwing it into the environment. The method of extinguishing a fire is implemented in a fire extinguishing system in a volume with containers with liquefied combustible gas, containing a source of inert gas located outside the volume and connected to this volume by an inert gas supply line with shutoff valves, into which a gas-liquid heat exchanger is introduced, located outside the volume, the outlet is liquid of which is connected to the discharge line into the environment, and the liquid inlet is connected to the liquefied gas delivery line, the gas inlet of this heat exchanger is docked to the inert gas supply line, and its gas outlet is connected to the volume. This solution allows using the "cold" stored in liquefied combustible gas, and due to the "deep" cooling of the inert gas suppressing the fire, significantly reduce its required amount [RU 2256472, MKI A62S 3/02. Publ. 20.07.2005].

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

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

- 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) itself in this case becomes explosive;

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

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

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

A device for extinguishing a combustible liquid in a tank is known, consisting of a low expansion foam generator and a foam container. The foam generator is made in the form of a housing with a nozzle for feeding a foaming agent solution into the housing and with an opening for supplying air to the housing. The nozzle is multi-jet. A mixing chamber is located in the foam generator housing, the inlet of which is installed opposite the nozzle, and the outlet is connected to a foam container having an outlet 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 by one of them to the combustible liquid in the tank, and the other onto the inner wall of the tank. Between the outlet for foam from the foam container to the tank and the mixing chamber there is a sealing membrane made with the possibility of destruction during fire extinguishing [RU 2232041, MKI A62S 3/06. Publ. 10.07.04].

The disadvantage of the RU 2232041 device is the unreliability of the design, since when a vapor-air mixture explodes in a tank, the foam container is destroyed, which will lead to a significant increase in the time interval between the onset of ignition and the elimination of the fire. There is a risk of destruction of the reservoir and, as a result, the spill of combustible products over large areas, their ignition, as well as a high probability of a fire in adjacent reservoirs.

A known method of protecting tanks with flammable and combustible liquids from an explosion and in case of fire by supplying from the input unit from above to the inner wall of the tank at least two jets of extinguishing agent - low expansion foam, according to which the extinguishing agent is fed in horizontal jets along the wall of the tank in one direction or simultaneously clockwise and counterclockwise, so that the axes of the jets do not intersect, while the extinguishing agent is supplied with a pressure that ensures the formation of a ring of extinguishing agent on the tank wall, and low expansion foam or water is used as the extinguishing agent. 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 agents are fed into the tank at the same time [RU 2334532, MKI A62S 3/06. Publ. 09/27/2008].

A device for implementing the method according to RU 2334532, containing a unit for introducing a fire extinguishing agent with an outlet into the reservoir at one end and with a lid on the other and nozzles for supplying a fire extinguishing agent, additionally contains one or more nozzles for supplying fire extinguishing agents, fixed horizontally on one or two sides the input unit at an angle selected from the condition of the direction of the jets of fire-extinguishing substances along the wall of the tank; the axes of the nozzles fixed on opposite sides of the input unit are located in parallel horizontal planes; the input unit is made of material with strength characteristics exceeding the strength characteristics of the upper tank belt, and the tank roof, the input unit cover and its attachment to the unit are made of material with destructive characteristics lower than the destructive characteristics of the walls of the input unit and the upper tank belt. At the same time, foam generators, foam nozzles, water, fire extinguishing powder, inert gas, water vapor, foam generators and foam nozzles are placed in a housing with an air intake 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.

The disadvantages of this technology is the impossibility of its use to prevent ignition (arresting), extinguish fires and eliminate the consequences of fires from spills of LPG and LNG.

Known developed by VNIIPO of the Ministry of Internal Affairs of Russia, the department of fire protection of objects of the GUGPS of the Ministry of Internal Affairs of Russia and the Center for Strategic Research of Civil Protection of the Ministry of Emergency Situations of Russia recommendations "Ensuring fire safety of storage and processing facilities of liquefied hydrocarbon gases" for fire protection of a bunded isothermal tank hydrocarbon gases ". Recommendations. http://files.stroyinf.ru/Data2/1/4293831/4293831044.htm].

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

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

- steam or water curtains around the embankment perimeter to limit the spread of LPG vapors during its spills and leaks by entraining them with sprayed jets of water or steam upwards and diluting them with air to concentrations below the LEL, which should be switched on immediately after an accident occurs automatically from the warning devices of pre-explosive gas concentrations;

- powder fire extinguishing installations based on dry powders of sodium bicarbonate or potassium bicarbonate for extinguishing the LPG flame in isothermal tanks in places of possible LPG leaks (areas where fittings, valves, equipment of working platforms, places of installation of shut-off and other fittings, pumping station);

- automatic stationary foam extinguishing installations for fire protection of embankments of LPG tanks (fast localization of fire and reduction of the flame torch due to an insulating foam layer) based on foam generators with increased productivity of high expansion foam with a foam ratio of 700-800 without forced air blowing from an electric fan.

A stationary foam extinguishing system according to these recommendations includes:

- system and sensors for detection and notification of fire or LPG spill in the embankment;

- device for switching on the water supply system;

- device for dosing the foam concentrate into the dry pipe line;

- containers with a concentrate of a synthetic foaming agent suitable for obtaining high-expansion foam;

- high expansion foam generators installed on the edge of the embankment.

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

The technical disadvantages of the specified method and device is its applicability only for low-tonnage stationary LPG storage facilities, since the range of supply of high-expansion foam with a multiplicity of 600-700 is usually only about 3 m, which causes the inefficiency and often the impossibility of using these solutions when stopping and extinguishing emergency LPG and LNG fires. spills of liquefied flammable gases during their transportation, processing and use.

Known developed and patented earlier by the applicant, developed and patented earlier by the applicant, a method and system for liquidating emergency spills of liquefied natural gas or liquefied hydrocarbon gas include processing the surface of liquefied gas with an air-water foam of medium expansion based on a synthetic hydrocarbon foaming agent with the production and subsequent disposal of gas-saturated foam. As a result, a gas-saturated foam is formed in the form of a layer of porous ice, a layer of frozen gas-saturated foam and a layer of liquid gas-saturated foam, located successively on the surface of the liquefied gas, which ensures a decrease in the gas concentration above the surface of the gas-saturated foam below the lower concentration limit of flame propagation [RU 2552968 A62C3 / 02. Publ. 10.06.2015. Bul. No. 16].

The disadvantage of solutions according to RU 2552968 is the possibility of supplying medium expansion foam only at distances that are insufficient to eliminate the consequences of large-scale accidents.

The known method and system for liquidation of emergency spills of liquefied natural gas or liquefied hydrocarbon gas, including the surface treatment of liquefied gas with combined water-air foam of low and medium expansion based on synthetic hydrocarbon foaming agent with the receipt and subsequent disposal of gas-saturated foam. As a result of the impact, the combined jet of low and medium expansion water-air foam formed upon contact of jets of low and medium expansion foam forms a layer of gas-saturated foam on the surface of the liquefied gas spill in the form of a layer of porous ice, a layer of frozen gas-saturated foam, and a layer of liquid gas-saturated foam, which are sequentially located on the surface of the liquefied gas. providing a decrease in the gas concentration above the surface of the gas-saturated foam below the lower concentration limit of flame propagation and the possibility of subsequent disposal of the gas-saturated foam [RU 2552969 A62C3 / 02. Publ. 10.06.2015. Bul. No. 16].

The known method and system for stopping (preventing fire, explosion and reducing the intensity of combustion) spills of liquefied natural gas (LNG) or liquefied petroleum gas (LPG), then together - liquefied gas (LNG), including the treatment of the surface of the liquefied gas with water-air foam of medium expansion based on synthetic hydrocarbon foaming agent with the formation of a foam layer on the surface of the liquefied gas, providing a decrease in the gas concentration above the surface of the foam layer below the lower concentration limit of flame propagation. As a result, the efficiency of LPG and LNG cupping is increased, the possibility of safe and controlled liquidation of LHG spills is provided, the formation and ignition (explosion) of a gas-air mixture of gas and air during LHG spills is prevented. [RU 2552971 A62C 3/02. Publ. 10.06.2015. Bul. No. 16].

The closest in technical essence and the achieved technical result (prototypes) are the method and system for stopping (preventing ignition, explosion and reducing combustion intensity) of spills of liquefied natural gas (LNG) or liquefied petroleum gas (LPG), developed and patented earlier by the applicant gas (SG) with a combined water-air foam of low and medium expansion based on a synthetic hydrocarbon foaming agent 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. As a result, the efficiency of suppression of LPG and LNG spills increases, the possibility of safe and controlled liquidation of LHG spills is provided, the formation and ignition (explosion) of a gas-air mixture of gas and air is prevented during LHG spills [RU 2552972 A62C 3/02. Publ. 10.06.2015. Bul. No. 16 (prototype)].

The disadvantage of the method according to the prototype RU 2552972 is that the low expansion foam jet, having a relatively higher density and a large supply of kinetic energy compared to the medium expansion foam jet, reaches the surface of the liquefied gas spill faster and, as a result of the presence of an increased water content and mechanical efforts of impact on the surface of the spill, causes an increase in the evaporation of liquefied gas, since it is known that mechanical influences and the flow of water to the surface of the liquefied gas enhances its evaporation and, accordingly, increases the concentration of explosive gas vapors in those places where, due to the lower density and a smaller supply of kinetic energy the jet of medium expansion foam does not reach.

Task and technical result

According to the majority of experts in the field of ensuring fire and explosion safety in general, and fire and explosion safety of fuel and energy complexes, in particular, experience and regulatory support of fire and explosion safety when working with LPG and LNG at present in Russia, especially for emergencies at transportation and unloading / loading of LPG and there is practically no LNG, which is due to the following main circumstances:

- the volumes of storage and transportation tanks for LPG and LNG are dozens of times larger than conventional tanks for flammable and combustible liquids (flammable and combustible liquids), therefore, the area of their spills and fires, respectively, is tens of times larger than in accidents with conventional flammable and combustible liquids;

- technologies for cryogenic liquefaction of hydrocarbons, especially in the variant of large-scale production, and the use of liquefied combustible gases appeared relatively recently, in the last 30-40 years;

- liquefied combustible gases as combustible substances have specific thermophysical and thermodynamic properties that differ significantly from the thermophysical and thermodynamic properties of conventional flammable and combustible liquids.

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

During the 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 6000 m ^{3 of the} most dangerous gas-air mixture of stoichiometric composition and about 12000 m ^{3 of a} simply fire-and-explosive 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 when the ignition source (ignition) of this gas-air mixture appears.

As the long-term experience of Gazprom shows, in the event of dangerous situations - gas manifestations (gas leaks), in 30-40% of cases of such leaks, an ignition source 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 area of accumulation of an explosive gas-air mixture appeared and led to its ignition, fire or explosion. ) ignite not in 30-40% of cases, but in 90% of cases [Departmental norms for the design of installations for the production and storage of LNG, cold storage and gas filling stations. 4-51 - 1-88. February 21, 2013; 5. NPB 107-97].

According to the calculations of specialists of the Federal State Budgetary Institution "27 NC" of the Ministry of Defense of the Russian Federation, the power of the explosion of a vapor-air cloud with a one-time outflow of a thousand tons of liquefied LNG in an air blast wave will be comparable to the explosion power of a nuclear weapon of 10 kilotons in TNT equivalent, which is comparable to the explosion power of an atomic bomb in Hiroshima!

Therefore, a practical solution to the problems of reducing the rate of evaporation of combustible gas from the surface of a liquefied gas spill in order to prevent an explosion of a gas-air mixture that is rapidly forming above the surface of the spill, to prevent ignition (suppression) and extinguish fires in case of emergency and technological spills of liquefied natural gas or liquefied petroleum gas is extremely important.

The technical result obtained when using the invention is to improve the efficiency of stopping emergency and technological spills of liquefied natural gas (LNG) or liquefied petroleum gas (LPG), then together - "liquefied gas (LNG)", by:

effective prevention of fires, explosions, reducing the intensity of combustion and extinguishing fires, then - stopping, emergency spills of liquefied gas at a distance of up to 150 meters or more with a significantly softer effect of hybrid foam jets on the spill surface with a significant decrease in the rate of gas evaporation from the spill surface and, accordingly with a slowdown in reaching an explosive gas concentration above the spill surface;

accelerating the formation of a layer of gas-saturated foam on the surface of the spill, which ensures a decrease in the gas concentration above the surface of the gas-saturated foam below the lower concentration limit of flame propagation;

rapid application to the surface of the liquefied gas spill from a safe distance of the hybrid foam with an advanced rate of obtaining a layer of gas-saturated foam on the surface of the liquefied gas relative to the average rate of ascent of the evaporating gas flow;

ensuring the possibility of safe and controlled liquidation of spills of liquefied gas with the possibility of disposing of the spilled liquefied gas;

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

prevention of ignition (fire) of liquefied gas spills;

ensuring the possibility of managing the development of an emergency by applying hybrid foam from a safe distance to the surface of a gas spill with high intensity and from generators with a large second flow rate of the foaming solution and, accordingly, with a large radius of controlled supply of foam jets to the accident zone;

ensuring the possibility of safe controlled utilization of gas vapors by controlled combustion and utilization of spilled liquefied gas in the form of frozen and liquid gas-saturated water-air foam.

The essence of the invention

When stopping emergency and technological spills of liquefied natural gas and liquefied hydrocarbon gas, hereinafter referred to as "liquefied gas", including the application of water-air foam to the surface of the liquefied gas spill, according to the invention, hybrid water-air foam is applied to the surface of the liquefied gas spill with a predominant ratio of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent motion under a pressure of 0.6-1.4, mainly 0.8-1.2 MPa, coaxial, contacting or mutually intersecting jets of air-mechanical foam of low expansion with a predominant ratio of 5 to 15 and jets of air-mechanical foam of medium expansion with a predominant expansion from 25 to 70, with their corresponding ratio in the flow rate of the foaming agent used for their formation from 8: 1 to 1: 1, with their corresponding volumetric ratio from 0.1 to 1.0.

Hybrid water-air foam is obtained as a result of turbulent mixing in the process of concurrent motion of jets of air-mechanical foam of low and medium expansion, formed by foaming an aqueous solution of a foaming agent with air.

Hybrid water-air foam is applied to the surface of the liquefied gas spill:

with an advanced rate of obtaining gas-saturated foam on the surface of the liquefied gas relative to the average rate of ascent of the flow of the evaporating gas;

with an intensity of its supply of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas spill over the foaming agent solution within a time period not exceeding 1-25 seconds after the liquefied gas spill.

Disposal of the gas evaporating from the spill is carried out by means of its controlled combustion over the hybrid foam layer at the place of the liquefied gas spill.

The gas-saturated foam obtained on the surface of the liquefied gas spill is disposed of:

by controlled combustion of gas-rich foam at the site of a liquefied gas spill;

by controlled combustion of gas-rich foam after its movement from the place of the spill of liquefied gas;

by natural or artificial destruction of gas-saturated foam with subsequent ventilation or weathering of the disposal site to volumetric gas concentrations below the lower concentration limit of flame propagation.

Hybrid water-air foam is produced and applied to the surface of a liquefied gas spill:

by means of generating foam of low and medium expansion with automatic, manual or remote control system and / or oscillation;

by means of generating foam of low and medium expansion, installed at the facilities of production, storage, processing or transportation of liquefied gas;

by means of generating foam of low and medium expansion, permanently installed at facilities with a high degree of fire and explosion hazard;

by means of generating air-mechanical foam of low and medium expansion, installed on mobile railway, air, waterfowl or automobile, vehicles or trailers;

by means of generating air-mechanical foam of low and medium expansion, placed in containers installed on the decks of sea vessels and offshore platforms or on vehicles of shore-based facilities.

The problem is solved and the required technical result is also achieved by the fact that the system for liquidating emergency and technological spills of liquefied natural gas or liquefied hydrocarbon gas, hereinafter referred to as "liquefied gas", by applying water-air foam to the surface of the liquefied gas spill, according to the invention, contains means for generating air low expansion mechanical foam and means for generating air mechanical foam of medium expansion, made with the possibility of obtaining and applying on the surface of a liquefied gas spill at least one jet of hybrid water-air foam obtained as a result of turbulent mixing in the process of concurrent motion of coaxial, touching or mutually intersecting jets low expansion air mechanical foam and medium expansion air mechanical foam.

In this case, the system contains means for generating low expansion air-mechanical foam with a multiplicity of 5 to 15 and means for generating air-mechanical foam of an average expansion with a multiplicity of 25 to 70, made with the possibility of obtaining and applying at least one jet to the surface of the liquefied gas spill hybrid water-air foam with a multiplicity with a multiplicity of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent movement of jets of air-mechanical foam with a multiplicity of 5 to 15 and air-mechanical foam with a multiplicity of 25 to 70 and which is made with the possibility of implementing the described above way.

Low and medium expansion foam generating means used to obtain hybrid foam can be manufactured:

with automatic, manual or remote control and / or oscillation;

installed at facilities for the production, storage, processing or transportation of liquefied gas;

permanently installed at facilities with a high degree of fire and explosion hazard;

installed on mobile railway, air, waterfowl or automobile, vehicles or trailers;

installed on the decks of ships and offshore platforms or on vehicles of shore-based facilities.

As separate elements and units of the system equipment for the implementation of the proposed method, various technologies, materials and design solutions known and traditional for fire-fighting technology can be used, which are usually used in the elimination of accidents, prevention of ignition and explosion (stopping) and extinguishing fires of liquefied combustible gases.

Brief Description of Drawings

FIG. 1 and FIG. 2 shows, respectively, a side view and a top view of a scheme for the formation of a hybrid foam 4 with a multiplicity of 20 to 40, obtained as a result of mutual mixing in the process of concurrent movement of coaxial, contacting or intersecting jets 1 of air-mechanical foam of low expansion with a multiplicity of 5 to 15 and jets 2 air-mechanical foam of medium expansion with expansion from 25 to 70.

The same drawings show the possibility of forming a hybrid foam with a multiplicity of 20 to 40, obtained at a distance of 0.2-0.8 of the total length L from the generator or combined foam generators L of a jet of hybrid foam obtained as a result of mutual mixing in the process of coaxial motion of coaxial , touching or intersecting jets of low expansion air-mechanical foam with a multiplicity of 5 to 15 and jets of air-mechanical foam of medium expansion with a multiplicity of 25 to 70.

FIG. 3, 4 and 5 - sections A-A, B-B and V-C of the concurrent movement of jets of coaxial, contacting or intersecting jets 1 of low expansion air-mechanical foam with a ratio of 5 to 15 and jets of 2 air-mechanical foam of medium expansion with with multiplicity from 25 to 70, which at the beginning move coexistingly without mixing (section A-A in Fig. 3), then co-moving with partial mixing (section B-B in Fig. 4) and with complete mutual mixing to obtain a single jet 3 hybrid foam with a multiplicity of 20 to 40.

FIG. 3, 4 and 5 also show the structure of low expansion foam, medium expansion foam and hybrid foam obtained by turbulent mixing of low expansion foam with medium expansion foam.

FIG. 5 - the structure of a hybrid foam resulting from turbulent mixing of low expansion foam bubbles and medium expansion foam bubbles with the resulting average size of water-air foam bubbles with thickened Gibbs-Plateau channels.

FIG. 6 - a diagram of extinguishing a fire on the surface of a combustible liquid with a jet 3 of hybrid foam with a multiplicity of 20 to 40, resulting from mixing in the process of concurrent motion of coaxial, contacting or mutually intersecting jets 1 of air-mechanical foam of low expansion with a multiplicity of 5 to 15 and jets 2 air-mechanical foam of medium expansion with expansion from 25 to 70.

FIG. 7 - a torch of free combustion of liquid fuel at a landfill with dimensions of 50 x 25 m of the full-scale fire tests described in detail below at the oil refinery "Kirishinefteorgsintez" (Leningrad region, Kirishi), where the fire of a layer of liquid fuel was extinguished with the help of modernized foam generators PURGA and BLIZARD hybrid water-air foam.

FIG. 8, 9 show the process of extinguishing a fuel fire with a hybrid water-air foam during full-scale fire tests, Fig. 10 shows the stage of forming a layer of hybrid foam on the surface of the extinguished liquid fuel, and FIG. 11 is a view of the polygon after the completion of the foam attack with the hybrid foam.

FIG. 12 and 13 show photos of the modernized foam generators PURGA and BLIZARD developed by the applicant with combined shafts of air-mechanical foam of low and medium expansion, providing the formation and supply of hybrid water-air foam at a distance of up to 150 meters and more with a ratio of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent movement of jets of air-mechanical foam with a multiplicity of 5 to 15 and jets of air-mechanical foam with a multiplicity of 25 to 70.

Implementation of the invention

It is known that foam is the most effective and widely used extinguishing agent, which is a dispersed system consisting of cells - air (gas) bubbles separated by films of liquid containing a foaming agent [GOST R 50588-2012 Foaming agents for extinguishing fires. General technical requirements and test methods].

The ratio of the volumes of the gas and liquid phases (per unit volume) of the foam determines the structure and its properties. If the volume of the gas phase V _g exceeds the volume of the liquid V _{l by} no more than 10-20 times (low expansion foam), the foam cells filled with gas have a spherical shape. In such foams, gas bubbles are surrounded by relatively thick liquid shells. Spherical foams are characterized by a high liquid content and therefore low stability. Therefore, they are classified as metastable (conditionally stable). In unstable foams, the so-called Plateau effect is observed: the liquid phase is removed from the partitions, flowing out under the action of gravity, and rapid coalescence occurs (from the Latin coalesce - I grow together, I unite) - the merging of touching gas bubbles. In the foam, the gas bubble cannot move freely either in the vertical or in the horizontal plane. It is, as it were, "squeezed" by other bubbles adjacent to it.

With an increase in the V g / V _{l ratio, the} thickness of the liquid film separating the gas volumes decreases, and the gas cavity loses its spherical shape. Medium expansion foams, in which the V _g / V _l ratio is several tens or even hundreds, have a multifaceted shape. Moreover, the shape of the polyhedra can be different - triangular prisms, tetrahedrons, irregularly shaped parallelepipeds. In the process of foam aging, the spherical shape of the cells transforms into a multifaceted one. Multifaceted foams are characterized by a low liquid phase content and are characterized by high stability. In such foams, individual bubbles are brought together and separated by thin "stretched elastic films". These films, due to their elasticity and a number of other factors, prevent the coalescence of gas bubbles. As the separation films become thinner, the bubbles come closer and closer, adjoin each other and acquire a clear polyhedron shape [Bobkov SA, Baburin AV, Komrakov PV. Physico-chemical foundations of development and extinguishing fires: textbook. manual / M .: Academy of State Fire Service of the Ministry of Emergency Situations of Russia, 2014. - 210 p.].

The main physical and chemical properties of the foam are:

multiplicity - the ratio of the volume of the foam to the volume of the foaming agent solution contained in the foam;

dispersion of - fineness bubbles (bubble size);

viscosity - the ability of the foam to spread over the surface;

resistance - the ability of the foam to resist the process of destruction [ibid.].

Depending on the magnitude of the multiplicity (K), foams are divided into four groups:

foam emulsions , K <3;

low expansion foams , 3 <K <20;

medium expansion foam , 20 <K <200;

high expansion foam, K> 200 [ Sharovarnikov A.F., Sharovarnikov S.A. Foam concentrates and foams for extinguishing fires. Composition, properties, application. M .: Pozhnauka, 2005. - 335 p.].

The dispersion of the foam is inversely proportional to the average bubble diameter.

It is known that the higher the dispersion, the higher the foam resistance and fire extinguishing efficiency. The degree of foam dispersion largely depends on the conditions for its production, including the characteristics of the equipment. The multiplicity and dispersion of the foam determine the insulating ability of the foam and its fluidity. [Bobkov S.A., Baburin A.V., Komrakov P.V. Physico-chemical foundations of development and extinguishing fires: textbook. manual / - M .: Academy of State Fire Service of the Ministry of Emergency Situations of Russia, 2014. - 210 p.].

The fire-extinguishing properties of foam are:

insulating effect - preventing the entry of combustible vapors, gases or air into the combustion zone, which causes the cessation of combustion;

cooling effect - due to the presence of a significant amount of liquid in predominantly low expansion foam.

The cooling effect of the foam is due to the water released from the foam.

The insulating effect is due to the formation of a foam layer that prevents oxygen from reaching the fire zone, including:

separation effect , which consists in isolating the liquid from the vapor phase;

the displacement effect , which causes the isolation of the combustible substance from the air;

blocking effect in which the foam prevents the evaporation of a flammable liquid.

Low expansion foams (3 <K <20) due to the significant amount of water in the interbubble partitions (in the Plateau-Gibbs channels), they predominantly exhibit a cooling fire extinguishing effect due to the cooling effect of the foam itself and the water released from the foam.

Medium expansion foam (20 <K <200) due to the insignificant amount of water in the interbubble partitions (in the Plateau-Gibbs channels), they predominantly exhibit an insulating fire extinguishing effect due to the creation of an atmosphere depleted in oxygen and saturated water vapor over the combustion zone, contributing to the slowdown and complete cessation of combustion.

At the same time, due to the more significant amount of water available in the foam of low expansion of water, and, accordingly, the higher density (weight per unit volume) of low expansion foam compared to medium expansion foams, it is possible to supply from longer distances, which significantly affects the safety of firefighters when large-scale and explosive accidents with liquefied gases.

A characteristic distinctive feature of the proposed technical solutions is the production and use of hybrid water-air foam based on synthetic hydrocarbon foaming agents with a frequency of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent motion of jets of air-mechanical foam with a frequency of 5 to 15 and jets of air-mechanical foam with a multiplicity of 25 to 70.

It has been experimentally established and theoretically substantiated that hybrid water-air foam with a multiplicity of 20 to 40, obtained on specially modernized equipment as a result of turbulent mixing in the process of concurrent motion of coaxial contacting or mutually intersecting jets of air-mechanical foam with a multiplicity of 5 to 15 and jets of air mechanical foam with an expansion rate from 25 to 70 significantly differs in its structure, viscosity, dispersion, rheological, thixotropic and other properties significant for explosion and fire prevention and fire extinguishing from the known properties of low and medium expansion foams based on hydrocarbon and fluorine-containing foaming agents.

It was revealed that as a result of turbulent mixing of low expansion foam bubbles and medium expansion foam bubbles in the hybrid foam, foam bubbles averaged in size are formed, larger in comparison with low expansion foam bubbles, but with thicker water-containing Plato channels compared to medium expansion foams. Gibbs.

As experimentally established, the structure of hybrid foam with a multiplicity of 20 to 40, resulting from turbulent mixing in the process of concurrent motion of jets of air-mechanical foam with a multiplicity of 5 to 15 and jets of air-mechanical foam with a multiplicity of 25 to 70 with unique in its structure and fire-extinguishing properties of water-air bubbles, it allows not only to better contain the high temperature of the flame without significant destruction of the volume of the hybrid foam itself, that is, to more effectively isolate the fire surface, but also to deliver the jet of hybrid foam over much longer distances compared to jets of medium foam multiplicity or combined jets of foam of low expansion and medium expansion.

It has also been experimentally established that when a hybrid foam with a multiplicity of 20 to 40 is applied to the surface of a liquefied natural or hydrocarbon gas spill, a synergistic effect is manifested due to the simultaneous action of several factors - cooling, dilution with water vapor in the atmosphere in the zone of evaporation and burning times, thermal insulation and a sharp decrease in concentration of gas vapors above the foam layer in the combustion zone up to a decrease in the rate of the chemical reaction and a subsequent decrease in the flame temperature to the extinction temperature.

This is due to the average dispersion and thickening of the Gibbs-Plateau water-containing channels of hybrid foam in comparison with foams of low and medium expansion or compared with foam in combined jets of low expansion and medium expansion foam.

Full-scale fire tests of modernized barrels to obtain hybrid foam produced by the applicant modernized barrels and foam generators have shown high efficiency of fire and explosion prevention and extinguishing of combustion of both flammable and combustible liquids, and bottling of liquefied natural and hydrocarbon gases.

The applicant carried out full-scale fire tests at the range, where with the help of the modernized installations of combined fire extinguishing "Purga" and "BLIZARD" developed by the applicant, effective extinguishing of the fuel layer was ensured on an area of 1250 m ² .

As shown by the test results, the modernized installations "Purga" and "BLIZARD" developed by the applicant, used to extinguish the fire, provide a soft and smooth supply of hybrid foam to the fire surface at increased distances of up to 150 meters or more without a rough effect on the burning area. that is, without mixing the upper fuel layer with the foam layer.

The multiplicity of the hybrid foam obtained on the modernized installations "Purga" and "BLIZARD" developed by the applicant was from 20 to 40 or 30 ± 10.

A synthetic hydrocarbon environmentally friendly foaming agent of the PO-6TS type of Russian production was used. The feeding range of the obtained hybrid foam was more than 150 m.

Full-scale fire tests of the modernized installations "Purga" and "BLIZARD" developed by the applicant have shown that the hybrid foam has a significantly milder effect on the burning surface and a higher fire extinguishing efficiency compared to foams of equipment supplying separately low and medium expansion foams or compared to combined foams low and medium expansion.

Experts attending the tests came to the conclusion that the equipment for "hybrid foam" produced by the applicant NPO "SOPOT" LLC can become an effective option for the use of foaming agents and foams that do not contain fluorine.

With all this ambiguity and uncertainty of the initial parameters of an emergency during the outflow or spill of liquefied gas (LNG and / or LPG), it is possible to distinguish the following emergency situations:

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

- marginal (weak) outflow of liquefied fuel gas from small holes;

- one-stage release of liquefied combustible gas followed by a prolonged outflow;

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

- total destruction of the reservoir, with an almost one-time outflow and spillage 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 the development of emergency situations:

- the expiration of the liquefied combustible gas before the ignition of the outflowing (spilled) liquefied combustible gas;

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

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

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

In addition to the specific situational features of accidents and disasters with 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 the significant size of the fire area, as well as the power of the explosion, if it occurs.

In low-hazard flare combustion with a jet outflow of a gaseous or even liquid phase of liquefied combustible gas through a small hole 5-6 mm in size, the local thermal power 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 hole, the level of its formation, wind strength, etc.).

Such torches can be extinguished with any kind of known extinguishing agent (water, foam, powder and even non-flammable gas) from any type of 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 an unloading ramp, etc.) have been difficult, and sometimes impossible, to extinguish with known fire extinguishing systems and means.

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

The use of the invention makes it quite possible in all the options discussed above and at all stages of emergency situations, with the exception of sudden explosions, by the proposed use of a combined foam of low and medium expansion, supplied to the stream or to the surface of the liquefied combustible gas with high intensity and from foam generators with a large second consumption foaming solution and, accordingly, with a sufficiently large radius of controlled, (regulated) foam jets supply to the accident zone with the formation of a hybrid foam layer on the surface of the liquefied combustible gas spill, which makes it possible to stop the development of a fire-and-explosive situation in the event of a liquefied combustible gas spill and to ensure the possibility of controlled elimination of the consequences of the spill liquefied fuel gas.

As shown by the complex of studies and full-scale fire tests carried out by the authors at the test sites of OJSC "Kirishinefteorgsintez" during the localization and relief of the consequences of accidents with liquefied combustible gas through the use of modernized installations of combined fire extinguishing "PURGA" and "BLIZARD" manufactured by the applicant, in most cases the situation can be taken under control over a time of the order of 1 - 2 seconds, and keep it under control for up to 15-30 minutes or more (depending on the scale and complexity of the accident, the amount of fuel spilled, the area of its spreading, the complexity of the object and others the 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 the explosion, reduce the area of a post-emergency fire or even prevent its occurrence, reducing the accident to a gradual, fire and explosion-proof evaporation of a spilled liquefied combustible gas or by organizing a controlled, controlled, slow burning out of foam saturated with combustible gas. from the surface of a liquefied combustible gas spill.

The invention is based on the following, experimentally identified and theoretically grounded initial ideas and assumptions about elementary processes over the "free" (or "covered") surface of the spilled liquefied combustible gas (LPG and LNG).

In an 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 "liquid surface mirror" or under the partial pressure of vapors (elastic vapors) with free liquid mirror surface.

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

The practical task of ensuring fire and explosion safety in all situations during these accidents is reduced to monitoring and controlling the concentration of vapors of liquefied combustible gas (LPG and LNG) in the entire area of the accident and during the entire time since the beginning of the accident by means of a liquefied combustible gas (LPG) spill formed above the surface. and LNG) according to the invention, a layer of hybrid water-air foam with a ratio of 20 to 40 based on a synthetic hydrocarbon foaming agent, consisting of an ice-cold low and medium expansion located directly on the surface of the spill and a layer of liquid hybrid water-air foam located above, mainly based on a synthetic hydrocarbon foaming agent.

Due to the fact that from the moment of the accident (spillage or outflow) of liquefied combustible gases are always at their surrounding temperature significantly higher than their boiling point, they begin to evaporate intensively.

In this case, the total rate of evaporation of the liquid is proportional to the area of their free surface, and when water droplets hit the liquefied gas, the evaporation increases sharply to possible boiling.

The main idea of the invention to ensure safety in case of accidents with liquefied combustible gas (LPG and LNG) is reduced to a quick, almost instantaneous taking under physical control of the entire free surface of an outflowing or spreading fire and explosive liquid of liquefied combustible gas from the moment the process of outflow or spreading begins with the desired use of automatic systems switching on and controlling the process of stopping and eliminating an accident with liquefied fuel gas by accelerating the formation of a layer of hybrid water-air foam with a multiplicity of 20 to 40 on the surface of the liquefied gas spill, mainly based on a synthetic hydrocarbon foam concentrate.

As a technical technique, a technical way to implement this idea of neutralization or relief of dangerous factors of accidents of this kind, the idea was adopted (and the corresponding technical methods were proposed) of operational coverage of the entire free surface of a liquefied combustible gas (LPG and LNG) spill with a hybrid water-air foam with a multiplicity of 20 to 40 predominantly based on a synthetic hydrocarbon foaming agent of a certain rate, with certain parameters and properties, with the use of certain technical devices, systems and devices.

The parameters, composition and properties of hybrid water-air foam with a multiplicity of 20 to 40, mainly based on a synthetic hydrocarbon foaming agent, as well as modes and methods of its supply, are determined and justified experimentally, taking into account the thermodynamic and thermophysical features of its interaction during its direct contact with the surface of the liquefied fuel spill. gas (LPG and LNG).

The specificity of the problem solved by the invention is that with all other options for using air-mechanical and even chemical foams for the purpose of extinguishing fires of flammable liquids (FL) and combustible liquids (GF) and / or even protecting them from ignition, a very significant role, and when extinguishing fires of flammable liquids (GF), even a dominant role is played by the process of cooling the surface of a burning liquid from its boiling point, to which its surface heats up already in the first 3-5 minutes of the fire, to a lower temperature (for the option of extinguishing a fire of flammable liquids (GF ), generally to temperatures below the flash point.

When extinguishing a fire of flammable liquids (FL), 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 intensity of evaporation of flammable liquids and combustible liquids 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 fire flame zone, and the combustion of flammable and combustible liquids stops. This is how the process of extinguishing flammable and combustible liquids fires takes place.

The thermophysical picture of the thermal interaction of contacting media when air-mechanical foams are applied to the surface of the SG looks significantly different.

The temperature of air-mechanical foam rarely goes beyond +1 to + 15 ° C. This means that the heat drop (thermal head) from foam to LPG is of the order of 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 gain from the foam, during its application, does not decrease, but, on the contrary, intensifies.

Thus, the process of preventing ignition (stopping) of the process of passage of combustible gas vapors into the space above the foam, into the zone of possible combustion, is reduced to the processes of sorption, absorption, retention of the flow of vapors of liquefied combustible gas, which, according to the invention, can be provided by a foam layer of a certain composition, of 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, goes on continuously, and part of the foaming agent flows down through the foam and falls on the surface layer of liquefied combustible gas (LPG and LNG), the process of intensifying their evaporation, for The “warm” solution of the foaming agent continues to flow out continuously, but may be limited by the ice layer of frozen foam located directly on the surface of the liquefied fuel gas spill of the ice layer of the frozen hybrid foam.

It has been experimentally determined and theoretically substantiated that a special role in a situation of a liquefied fuel gas (LPG and LNG) spill is played by phase transformations at the foam / LPG and / or foam / LNG (foam / liquefied fuel gas) interface and the surface layer of liquid substances of liquefied fuel gas.

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

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 the dispersity 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 interface.

Therefore, the insulating and gas-insulating properties of a layered "sandwich" on the surface of a liquefied combustible gas spill largely depend on this: vapor of liquefied combustible gas, an ice layer, a layer of frozen gas-saturated foam and a layer of liquid gas-saturated foam or a layer of frozen gas-saturated foam and a layer of liquid gas-saturated foam ...

Further parameters of the evaporation process of a flammable substance of a liquefied combustible gas and the penetration of its vapors into the zone of possible controlled combustion of gas above a layer of gas-saturated foam or controlled combustion of a gas-saturated foam (concentration of combustible gas vapors above the foam or concentration of gas in the foam) depend on the thermophysical properties of the frozen foam layer and the next layer of liquid foam. From their thickness, gas permeability, thermal conductivity, sorption properties of the layer of frozen gas-saturated hybrid foam and the layer of liquid gas-saturated hybrid foam located above.

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

It has also been experimentally established that it is advisable to use the modernized Purga and BLIZARD installations produced by the applicant as hybrid foam generators for stopping and extinguishing LPG and LNG fires and disposing of LPG and LNG spills, which ensure the formation and supply of hybrid foam at a distance of up to 150 meters.

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

Specific parameters for liquidation of emergency spills, fire and explosion prevention, suppression and extinguishing of a fire of spills of liquefied natural gas or liquefied hydrocarbon gas with a water-air hybrid foam with a multiplicity of 20 to 40 were determined experimentally and practically verified in the process of full-scale fire tests.

Full-scale tests in field conditions have shown a confident solution to the task and achieve the required technical result, namely, the implementation of the present invention makes it possible to increase the efficiency of arresting emergency spills of liquefied natural gas and liquefied hydrocarbon gas, then together - "liquefied gas", with the provision of safe and controlled liquidation of emergency spills of liquefied gas, prevention of the formation and ignition (explosion) of a gas-air mixture of gas and air in case of emergency spills of liquefied gas, prevention of ignition (fire) of emergency spills of liquefied gas, effective suppression and extinguishing of fires, emergency spills of liquefied gas at a distance of up to 150 meters and more, prevention ignition and controlled burning of liquefied gas after stopping and extinguishing a fire of emergency spills of liquefied gas.

Considering the novelty of the set of essential features, the technical solution to the problem, the inventive step and the materiality of all general and particular features of the invention, proved in the section "Prior Art" and "Disclosure of the Invention", proved in the section "Implementation and Inventions", the technical feasibility and industrial applicability of the invention, the solution of the inventive problem and the confident achievement of the required technical result in the implementation and use of the invention, in our opinion, the claimed group of inventions meets all the requirements of patentability 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 allow the invention to be implemented in an industrial way.

In addition, the analysis of the totality of essential features of the group of inventions and the single technical result achieved with their use shows the presence of a single inventive concept, a close and inextricable connection between the method and the system for its implementation. This makes it possible to combine inventions in one application, that is, to meet the requirements of the criterion of unity of invention.

Claims (27)

1. A method of stopping spills of liquefied natural gas or liquefied hydrocarbon gas, comprising applying a layer of water-air foam to the surface of the liquefied gas spill, characterized in that hybrid water-air foam is applied to the surface of the liquefied gas low expansion mechanical foam and medium expansion air mechanical foam . 2. The method according to claim 1, characterized in that hybrid water-air foam is applied to the surface of the liquefied gas spill with a multiplicity of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent movement of jets of air-mechanical foam of low expansion with a multiplicity of 5 to 15 and jets of air-mechanical foam of medium expansion with expansion from 25 to 70 . 3. The method according to claim 1, characterized in that hybrid water-air foam is applied to the surface of the liquefied gas spill with a multiplicity of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent motion of coaxial, contacting or mutually intersecting jets of air-mechanical foam of low expansion with a multiplicity of 5 to 15 and air-mechanical foam of medium expansion with a multiplicity of 25 to 70. 4. The method according to claim 1, characterized in that a hybrid water-air foam is applied to the surface of the liquefied gas spill with a multiplicity of 20 to 40, obtained as a result of turbulent mixing of jets of air-mechanical foam of low expansion with a multiplicity of 5 to 15 and air-mechanical foams of medium expansion with a ratio of 25 to 70 with their corresponding ratio in terms of the consumption of the foaming agent solution used for their formation from 8: 1 to 1: 1. 5. The method according to claim 1, characterized in that on the surface of the liquefied gas spill, a hybrid water-air foam of medium expansion is applied with a ratio of 20 to 40, obtained as a result of turbulent mixing of jets of air-mechanical foam of low expansion with a ratio of 5 to 15 and air -mechanical foam of medium expansion with expansion from 25 to 70 with their corresponding volumetric ratio from 0.1 to 1.0. 6. The method according to claim 1, characterized in that hybrid water-air foam is applied to the surface of the liquefied gas spill with a multiplicity of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent movement under a pressure of 0.6-1.4, mainly 0, 8-1.2 MPa of jets of low expansion air-mechanical foam with a ratio of 5 to 15 and jets of air-mechanical foam of medium expansion with a ratio of 25 to 70. 7. The method according to claim 1, characterized in that the hybrid water-air foam is applied to the surface of the liquefied gas spill at a leading speed relative to the average ascent rate of the evaporating gas flow. 8. The method according to claim 1, characterized in that the hybrid water-air foam is applied to the surface of the liquefied gas spill with an intensity of its supply of at least 0.5-1.0 l / s per m ^{2 of the} surface of the liquefied gas spill over the foaming agent solution. 9. The method according to claim 1, characterized in that the hybrid water-air foam is applied to the surface of the liquefied gas spill within a time period not exceeding 1-25 seconds after the liquefied gas spill. 10. The method according to claim 1, characterized in that the hybrid water-air foam is applied to the surface of the liquefied gas spill to obtain a layer of gas-saturated foam that reduces the gas concentration above the surface of the gas-saturated foam below the lower concentration limit of flame propagation. 11. The method according to claim 10, characterized in that the gas-saturated foam is disposed of by controlled combustion of the gas-saturated foam at the location of the liquefied gas spill. 12. The method according to claim 10, characterized in that the gas-saturated foam is disposed of after it has been moved from the place of the liquefied gas spill. 13. A method according to claim 10, characterized in that the gas-saturated foam is utilized by natural or artificial destruction of the gas-saturated foam, followed by aeration or weathering of the disposal site to the volumetric gas concentration below the lower concentration limit of flame propagation. 14. A method according to claim 1, characterized in that the gas evaporating from the spill is utilized by means of its controlled combustion over a layer of hybrid foam. 15. The method according to claim 1, characterized in that the hybrid water-air foam is obtained and applied to the surface of the liquefied gas spill by means of low and medium expansion foam generation with an automatic, manual or remote control system and / or oscillation. 16. The method according to claim. 1, characterized in that the hybrid water-air foam is obtained and applied to the surface of the liquefied gas spill by means of foam generation of low and medium expansion, installed at the facilities of production, storage, processing or transportation of liquefied gas. 17. The method according to claim 1, characterized in that the hybrid water-air foam is obtained and applied to the surface of the liquefied gas spill by means of foam generation of low and medium expansion, permanently installed at objects with a high degree of fire and explosion hazard. 18. The method according to claim 1, characterized in that the hybrid water-air foam is obtained and applied to the surface of the liquefied gas spill by means of generating air-mechanical foam of low and medium expansion, installed on mobile railway, air, waterfowl or automobile, vehicles or trailers ... 19. The method according to claim 1, characterized in that the hybrid water-air foam is obtained and applied to the surface of the liquefied gas spill by means of generating air-mechanical foam of low and medium expansion, placed in containers installed on the decks of sea vessels and offshore platforms or on transport facilities of shore-based facilities. 20. A system for coping with emergency spills of liquefied natural gas or liquefied hydrocarbon gas, characterized in that it contains means for generating air-mechanical foam of low expansion and means for generating air-mechanical foam of medium expansion, made with the possibility of obtaining and applying to the surface of the spill of liquefied gas at least measure of one jet of hybrid water-air foam, obtained as a result of turbulent mixing in the process of concurrent movement of jets of air-mechanical foam of low expansion and air-mechanical foam of medium expansion. 21. The system according to claim 20, characterized in that it contains means for generating air-mechanical foam with a multiplicity of 5 to 15 and means for generating air-mechanical foam with a multiplicity of 25 to 70, made with the possibility of obtaining and applying to the surface of the spill of liquefied gas at least one jet of hybrid water-air foam with a multiplicity of 20 to 40, obtained as a result of turbulent mixing in the process of concurrent movement of jets of air-mechanical foam with a multiplicity of 5 to 15 and air-mechanical foam with a multiplicity of 25 to 70. 22. The system according to claim 20, characterized in that it is configured to implement the method according to any one of claims. from 1 to 19. 23. The system of claim. 20, characterized in that the means for generating low and medium expansion foam are made with automatic, manual or remote control and / or oscillation. 24. The system of claim. 20, characterized in that the means for generating low and medium expansion foam are manufactured installed at the facilities of production, storage, processing or transportation of liquefied gas. 25. The system of claim. 20, characterized in that the means for generating low and medium expansion foam are made permanently installed at facilities with a high degree of fire and explosion hazard. 26. The system of claim. 20, characterized in that the means for generating low and medium expansion foam are made installed on mobile railway, air, waterfowl or automobile, vehicles or trailers. 27. The system of claim. 20, characterized in that the means for generating low and medium expansion foam are made installed on the decks of sea vessels and offshore platforms or on vehicles of shore-based facilities.

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