Positive pressure type multi-agent combined foam fire extinguishing system and application method

Abstract

The invention discloses a positive pressure type multi-agent combined foam fire extinguishing system. The device comprises a foam proportion mixing device, a mixed gas supply device, a gas-liquid mixer and a foam release device. The mixed liquid flowmeter is connected with an inlet of the liquid flow regulating valve through a pipeline, the liquid flow regulating valve is connected with one inlet of the gas-liquid mixer, and the other inlet of the gas-liquid mixer is connected with the mixed gas supply device; the mixed gas supply device provides a chemical fire extinguishing agent and air mixed gas, and the mixed gas supply device controls the proportion of the mixed gas injected into the foam mixed liquid according to the size of the foam mixed liquid flow meter; the gas-liquid mixer is used for fully mixing and foaming the foam mixed liquid and the mixed gas to form fire extinguishing foam with physical and chemical inhibition functions, and the fire extinguishing foam is conveyed to the foam release device through a pipeline. According to the scheme, the advantages of fire control and cooling performance of compressed air foam on low-boiling-point flammable liquid fire disasters and rapid and efficient fire extinguishing of chemical gas foam on oil steam remaining fire are combined.

Description

Technical Field

[0001] The invention relates to a positive pressure multi-agent combined foam fire extinguishing system and an application method, belonging to the technical field of fire extinguishing. Background Art

[0002] The petrochemical industry is a pillar industry of my country's national economy. With the intensive, refined and gigantic development of petrochemical industry, a large number of low-boiling point flammable liquid storage tanks with high fire risk and difficult fire fighting, such as naphtha, condensate, light reforming liquid, etc., have emerged, and the capacity of a single tank is getting larger and larger, gradually developing from the current common 5000 m3 and 10000 m3 to 20000 m3 or even larger capacity.

[0003] Low-boiling-point flammable liquids with a boiling point below 45°C, such as naphtha, condensate, and light reforming liquid, have low surface tension, low boiling point, high saturated vapor pressure, and strong volatility. Their saturated vapor pressure is more than 10 times that of standard n-heptane liquid fuel. Traditional single water-forming film foam, protein foam, anti-solvent foam, fluorine-free foam and other fire-fighting foams alone cannot suppress their rapid volatilization. Even if covered with a certain thickness of foam, oil vapor can still penetrate the foam layer, forming a residual flame (hereinafter referred to as "afterfire") that continues to burn and constantly changes its position and size. Once the foam supply stops or the foam dissipates, these "afterfires" will quickly reignite the tank fire. Therefore, the existing ordinary foam fire-fighting technology relies on the covering effect of conventional foam and water film to meet the fire extinguishing needs of low-boiling-point flammable liquids, and there are problems such as difficulty in extinguishing fires, easy re-ignition, and ineffective response.

[0004] Patents CN101371944B and CN202315035U disclose a foam fire extinguishing system using clean gases such as heptafluoropropane and trifluoromethane as foaming agents. The gas foam fire extinguishing product is composed of clean gas fire extinguishing agent and foam fire extinguishing agent, and has the dual fire extinguishing effects of foam coverage and gas chemical inhibition. However, the foaming gases in this method are all expensive clean gases such as heptafluoropropane and trifluoromethane, which leads to high cost of the fire extinguishing system and cannot be applied to large low-boiling point storage tanks with large amounts of fire extinguishing agents, making it difficult to popularize widely. In addition, the clean gases such as heptafluoropropane used are potent greenhouse gases (GWP=2900) and have been included in the list of controlled substances in the Kigali Amendment to the Montreal Protocol. Under the new national dual-carbon situation, they are facing the situation of being gradually restricted and eliminated. The new generation of environmentally friendly and efficient clean chemical gas fire extinguishing agents generally have the problems of high boiling point and being liquid under normal conditions, and it is impossible to achieve efficient foaming based on this method.

[0005] Patents CN113509662A, CN218529607U, CN118236661A, and CN117339149A disclose foam fire extinguishing systems using trifluorobromide and perfluorohexanone as foaming agents, which achieve dual fire extinguishing effects of physical cooling coverage and chemical inhibition by injecting liquid trifluorobromide and perfluorohexanone into a foam mixture for foaming. However, trifluorobromopropene and perfluorohexanone have relatively high boiling points, which are 34°C and 48°C respectively. They are liquid under normal conditions. Directly injecting them into the foam mixture in liquid form for foaming will result in poor foaming effect, inability to fully exert the chemical inhibition effect, and insufficient fire extinguishing efficiency, because most of them are liquid and the gas ratio is very low. Especially when the proportion in the air is small and the concentration is low, the chemical gas will have a significant flame enhancement and combustion-supporting effect, resulting in poor fire extinguishing and inhibition effect on large oil tank fires. In addition, using high-boiling point fire extinguishing agents such as trifluorobromopropene and perfluorohexanone, which are all relatively expensive, as foaming agents will also result in excessively high costs for the fire extinguishing system, which has no practical value and cannot be widely popularized and applied.

[0006] Therefore, because the chemical fire extinguishing agents used are liquid at room temperature, the existing technology either uses chemical fire extinguishing agents with insufficient vaporization concentration or fails to fully vaporize, resulting in the inability to fully exert the fire extinguishing effect. There is an urgent need for a fire extinguishing system and method that can simply modify existing equipment to fully vaporize the chemical fire extinguishing agent to participate in the formation of fire extinguishing foam. Summary of the invention

[0007] In view of the deficiencies of the above-mentioned prior art, the present invention discloses a positive pressure multi-agent combined foam fire extinguishing system and application method which has strong isolation, covering and cooling capabilities, fast speed, excellent chemical inhibition performance, economic efficiency, and green environmental protection. The system can quickly cover and control low-boiling point flammable liquid fires with foam, continuously cool them down, and quickly extinguish residual oil vapor fires, thereby completely extinguishing low-boiling point flammable liquid storage tank fires. Both fixed fire extinguishing systems and mobile fire extinguishing equipment can be used.

[0008] According to an embodiment of the present invention, a first solution is provided:

[0009] A positive pressure multi-agent combined foam fire extinguishing system, comprising: a fire water tank, a water supply valve, a fire water pump, a foam proportion mixing device, a foam mixed liquid flow meter, a liquid flow regulating valve, a mixed gas supply device, a gas-liquid mixer, a central controller and a foam release device;

[0010] The fire water tank is connected to the fire water pump through a pipeline, and a water supply valve is provided on the pipeline to control the water supply; the fire water tank is also provided with a water supply valve;

[0011] The output end of the fire water pump is connected to the foam mixture flow meter through a pipeline;

[0012] The foam proportion mixing device is connected to the foam mixed liquid flow meter through a pipeline;

[0013] In the pipeline in front of the foam mixed liquid flowmeter, the water pumped out by the fire pump and the foam liquid output by the foam proportion mixing device are mixed, and the flow rate passing through is calculated by the mixed liquid flowmeter;

[0014] The mixed liquid flow meter is connected to the inlet of the liquid flow regulating valve through a pipeline, the outlet of the liquid flow regulating valve is connected to an inlet of the gas-liquid mixer, and the outlet of the gas-liquid mixer is connected to the foam release device;

[0015] Another inlet of the gas-liquid mixer is also connected to a mixed gas supply device;

[0016] The central controller is simultaneously connected to the foam proportion mixing device, the foam mixed liquid flow meter, the liquid flow regulating valve and the mixed gas supply device through wires or wirelessly, and detects and controls them;

[0017] The mixed gas supply device provides a chemical fire extinguishing agent-air mixed gas containing a gaseous chemical fire extinguishing agent, the proportion of the gaseous chemical fire extinguishing agent in the mixed gas provided by the mixed gas supply device can be adjusted in real time, and the mixed gas supply device accurately controls the proportion of the mixed gas injected into the foam mixed liquid in real time according to the size of the foam mixed liquid flow meter;

[0018] The gas-liquid mixer fully mixes the foam mixed liquid and the mixed gas to foam, forming a fire extinguishing foam with both physical and chemical inhibition functions, which is transported to the foam release device through a pipeline.

[0019] Further, the foam proportioning device comprises a foam liquid tank, the foam liquid tank is provided with a liquid replenishing valve, the foam liquid tank is connected to a foam liquid pump through a pipeline, a liquid supply valve is provided on the pipeline, the outlet of the foam liquid pump is connected to a foam liquid flow meter, and the outlet of the foam liquid flow meter is connected to a foam mixed liquid flow meter through a pipeline;

[0020] The foam liquid pump and the foam liquid flow meter are connected to the central controller via wires or wirelessly;

[0021] The central controller adjusts the rotation speed of the foam liquid pump according to the size of the foam mixed liquid flow meter, thereby controlling the foam mixing ratio;

[0022] The foam proportion mixing device accurately controls the proportion of foam liquid injected into the fire water in real time according to the size of the foam mixed liquid flow meter;

[0023] The foam proportioning device may also adopt an existing pressure-type foam proportioning mixer or a balanced foam proportioning mixer.

[0024] Further, the mixed gas supply device includes a screw air compressor, a chemical fire extinguishing agent storage device, a vaporizing device, a cooling system and a chemical fire extinguishing agent air mixer;

[0025] The screw air compressor is used as an air source to provide air, and the chemical fire extinguishing agent supplied from the chemical fire extinguishing agent storage device is vaporized through the vaporization device using the waste heat of the screw air compressor;

[0026] The hot air discharged from the screw air compressor is cooled by the cooling system, fully mixed with the vaporized chemical fire extinguishing agent in the chemical fire extinguishing agent air mixer, and injected into the gas-liquid mixer;

[0027] The screw air compressor includes a compressor head. After the air is compressed by the compressor head, the contained air is separated by an oil-gas separator, and the hot air passes through a pressure regulating valve and a hot air pipe into a vaporizing device;

[0028] The hot oil of the compressor is connected to the vaporization device through the compressor hot oil pipe, and then it is cooled by the cooling device and then returned to the screw air compressor through the compressor cold oil pipe;

[0029] The chemical fire extinguishing agent storage device comprises a chemical fire extinguishing agent tank, the chemical fire extinguishing agent tank is connected to a main control valve, the main control valve is connected to a volumetric pump, and the pumped chemical fire extinguishing agent is connected to a vaporizing device through a liquid chemical fire extinguishing agent pipe.

[0030] Furthermore, the main body of the vaporization device is a heat exchanger.

[0031] The heat exchanger comprises an inner tube and an outer tube; the outer tube wraps the inner tube, and the inner tube and the outer tube are connected by welding or flange sealing;

[0032] The outer tube is provided with a chemical fire extinguishing agent inlet and a chemical fire extinguishing agent outlet;

[0033] Both ends of the inner tube are respectively provided with a medium inlet and a medium outlet;

[0034] A chemical fire extinguishing agent passes between the outer tube and the inner tube; a medium passes through the inner tube;

[0035] Through the heat exchange of the heat exchanger, the heat of the medium is transferred to the chemical fire extinguishing agent to heat and vaporize the chemical fire extinguishing agent;

[0036] The specific temperature value of the chemical fire extinguishing agent in the pipeline is related to the boiling point and volatility of the chemical fire extinguishing agent, and the specific temperature value may range from the boiling point of the chemical fire extinguishing agent to 50° C. above the boiling point of the chemical fire extinguishing agent.

[0037] Further, the total length of the inner tube and the outer tube of the heat exchanger is determined according to the boiling point and volatility of the chemical fire extinguishing agent;

[0038] The heat exchanger comprises a first heat exchanger and a second heat exchanger;

[0039] The inner tube of the first heat exchanger conveys hot air and has a length ranging from 0.5m to 10m;

[0040] The inner tube of the second heat exchanger conveys the compressor hot oil, and the length ranges from 0.2m to 8m;

[0041] The chemical fire extinguishing agent inlet of the first heat exchanger is connected to the liquid chemical fire extinguishing agent pipe;

[0042] The chemical fire extinguishing agent outlet of the first heat exchanger is connected to the first inlet of the chemical fire extinguishing agent air mixer through a pipeline;

[0043] A first temperature sensor and a first control valve are arranged on the pipeline between the chemical fire extinguishing agent outlet of the first heat exchanger and the chemical fire extinguishing agent air mixer;

[0044] The medium inlet of the first heat exchanger is connected to the hot air pipe;

[0045] The medium outlet of the first heat exchanger is connected to a cooling system to further cool the hot air and finally input it into a chemical fire extinguishing agent air mixer;

[0046] A chemical fire extinguishing agent delivery pipeline is also connected to the pipeline between the first temperature sensor and the first control valve;

[0047] The chemical fire extinguishing agent delivery pipeline is connected to the chemical fire extinguishing agent inlet of the second heat exchanger, and a second control valve is arranged on the chemical fire extinguishing agent delivery pipeline;

[0048] The chemical extinguishing agent outlet of the second heat exchanger is connected to the second inlet of the chemical extinguishing agent air mixer through a gaseous chemical extinguishing agent pipe;

[0049] A second temperature sensor and a third control valve are provided on the pipeline between the chemical fire extinguishing agent outlet of the second heat exchanger and the chemical fire extinguishing agent air mixer;

[0050] The medium inlet of the second heat exchanger is connected to the hot air pipe;

[0051] The medium outlet of the second heat exchanger is connected to the cooling system to further cool the hot air and finally input it into the chemical fire extinguishing agent air mixer;

[0052] A first temperature sensor is arranged at the outlet of the chemical fire extinguishing agent to monitor the temperature of the chemical fire extinguishing agent in the pipeline to determine whether the chemical fire extinguishing agent has exceeded its boiling point and is completely vaporized. If the temperature of the chemical fire extinguishing agent in the pipeline exceeds a specific temperature value, the first control valve is opened and the second control valve is closed at this time, and the gaseous chemical fire extinguishing agent is directly injected into the chemical fire extinguishing agent air mixer through the first inlet to be fully mixed with the air to form a mixed gas;

[0053] If the temperature of the chemical fire extinguishing agent in the pipeline is lower than a specific temperature value, the second control valve is opened. At this time, the first control valve is closed and the third control valve is opened, and the chemical fire extinguishing agent that is not completely vaporized is passed into the second heat exchanger for further heating and vaporization. A second temperature sensor is respectively arranged on the chemical fire extinguishing agent outlet pipeline of the second heat exchanger. The gaseous chemical fire extinguishing agent that is fully heated and vaporized by the second heat exchanger is injected into the chemical fire extinguishing agent air mixer through the second inlet to be fully mixed with the air to form a mixed gas; the second temperature sensor is used to monitor the temperature of the gaseous chemical fire extinguishing agent in the pipeline in real time.

[0054] Further, the cooling system includes a hot oil cooler, a cooling fan, an air cooler, a buffer gas tank, an air flow meter and an air flow regulating valve;

[0055] One end of the hot oil cooler is connected to the medium outlet of the second heat exchanger, and the other end is connected to the compressor cold oil pipe;

[0056] One end of the air cooler is connected to the medium outlet of the first heat exchanger, and the other end is connected to the buffer gas tank;

[0057] The outlet of the buffer tank is connected to the air inlet of the chemical fire extinguishing agent air mixer;

[0058] An air flow meter and an air flow regulating valve are arranged on the connecting pipe between the buffer tank and the chemical fire extinguishing agent air mixer;

[0059] A cooling fan is provided on one side of the hot oil cooler and the air cooler.

[0060] Further, the chemical fire extinguishing agent air mixer comprises an outer wall and an inner core;

[0061] The outer wall forms a cross-shaped cavity, which is respectively provided with a first inlet, a second inlet, an air inlet and a mixed gas outlet;

[0062] The first inlet and the second inlet are arranged opposite to each other, and the air inlet and the mixed gas outlet are arranged opposite to each other;

[0063] An inner core is arranged inside the first inlet and the second inlet, and a dispersion hole is arranged on the inner core;

[0064] The inner core divides the cross-shaped cavity into a chemical fire extinguishing agent chamber, an air chamber and a mixed gas chamber;

[0065] The injected chemical fire extinguishing agent is ejected through the dispersion holes on the inner core and mixed with the air flowing into the air chamber to be fully mixed in the mixed gas chamber, and then injected into the gas-liquid mixer through the mixed gas outlet;

[0066] A first one-way valve, a second one-way valve and a third one-way valve are respectively provided at the first inlet, the second inlet and the mixed gas outlet to prevent gas backflow;

[0067] The number of the dispersed holes is 3 to 50, and the hole diameter is 0.1 mm to 3 mm.

[0068] Furthermore, the hot air in the oil-gas separator of the screw air compressor is introduced into the medium inlet of the first heat exchanger through the pressure regulating valve, the air cooled by the first heat exchanger is injected into the air cooler for further cooling and then transported to the buffer gas tank, and then introduced into the chemical fire extinguishing agent air mixer through the air flow meter and the air flow regulating valve;

[0069] The compressor hot oil in the oil-gas separator of the screw air compressor passes through the second heat exchanger and the hot oil cooler respectively, and then is injected into the compressor head;

[0070] The waste heat energy of the hot air from the screw air compressor and the hot oil from the compressor is used to heat and vaporize the liquid chemical fire extinguishing agent in two stages, so that the liquid chemical fire extinguishing agent with different boiling points and vaporization characteristics can be quickly and completely vaporized.

[0071] The volume pump, control valve, first temperature sensor, second temperature sensor, first control valve, second control valve, third control valve, air flow meter, and air flow regulating valve are connected to the central controller via signal lines or wirelessly.

[0072] The volumetric pump automatically adjusts the rotation speed according to the flow rate of the air flow meter, thereby controlling the output flow rate of the liquid chemical fire extinguishing agent;

[0073] The central controller is controlled by PLC or other automation methods;

[0074] The foam release device adopts a non-air-suction foam release device, which can adopt a foam cannon, a foam gun, a foam nozzle or a foam spray pipe;

[0075] The foam fire extinguishing agent is a water film-forming foam fire extinguishing agent, a protein foam fire extinguishing agent, an anti-solvent foam fire extinguishing agent, or a fluorine-free foam fire extinguishing agent;

[0076] The chemical fire extinguishing agent adopts a high boiling point environmentally friendly and efficient chemical gas fire extinguishing agent, and the boiling point is higher than 25°C.

[0077] According to an embodiment of the present invention, using the positive pressure multi-agent combined foam fire extinguishing system in the first embodiment provided by the present invention, a second embodiment is provided:

[0078] A positive pressure multi-agent combined foam fire extinguishing system application method, using the above-mentioned positive pressure multi-agent combined foam fire extinguishing system, the steps include:

[0079] S1, fire control and temperature reduction;

[0080] For low-boiling-point flammable liquid storage tank fires, highly stable compressed air foam is generated and applied to quickly control the low-boiling-point flammable liquid fire, and a foam blanket with a thickness of not less than 100mm is formed on the surface of the low-boiling-point flammable liquid to gradually cool the liquid down until it drops below the boiling point of the low-boiling-point flammable liquid, leaving only the residual fire of oil vapor on the surface of the foam blanket;

[0081] S2, extinguish open fire;

[0082] For the residual fire of low-boiling-point flammable liquid oil vapor on the surface of the foam blanket, chemical gas-air mixed gas foam or chemical gas foam is generated and applied to quickly and completely extinguish the residual fire of oil vapor on the surface of the foam blanket by chemical inhibition;

[0083] During the chemical gas-air mixed gas foam fire extinguishing process, the chemical fire extinguishing agent can be successfully vaporized and reach a fire extinguishing concentration in the bubbles of the foam;

[0084] S3, anti-reignition protection;

[0085] After the fire in the low-boiling point flammable liquid storage tank is completely extinguished, continue to apply high-stable compressed air foam for 1min~30min, maintain a 200-500mm foam blanket on the surface of the low-boiling point flammable liquid to keep it cooled and effectively prevent re-ignition.

[0086] Furthermore, the gas-liquid ratio of the highly stable compressed air foam in step S1 is not less than 5:1, and the foam supply intensity is 5L / (min·m 2 )~30L / (min·m 2 ), the calculation formula for the minimum bubble supply time of compressed air foam is:

[0087] ;

[0088] Where:

[0089] t1—minimum bubble supply time for fire control and temperature reduction, min;

[0090] h0—the amount of compressed air foam for initial fire control dissipation, mm; it is determined according to the possible fire scale of the protected object. The larger the fire scale, the higher the value of the compressed air foam for initial fire control dissipation, and the minimum value is not less than 50mm;

[0091] h—thickness of compressed air foam blanket, mm, not less than 100 mm;

[0092] q—foam supply intensity, L / (min·m 2 );

[0093] x—gas-liquid ratio;

[0094] In step S2, the chemical gas-air mixed gas foam supply intensity is 8L / (min·m 2 )~30L / (min·m 2 ), the gas-liquid ratio is not less than 1:1, the foam supply time t2 is 3min~30min, and the calculation formula of the foam mixture and air flow is:

[0095] ;

[0096] ;

[0097] Where:

[0098] Q 液 —Volume flow rate of foam mixture, m 3 / min;

[0099] Q 空 —Compressed air volume flow, m 3 / min;

[0100] A—protected area, m 2 ;

[0101] A—protected area, m 2 ;

[0102] q—foam supply intensity, L / (min·m 2 );

[0103] x—gas-liquid ratio;

[0104] The calculation formula for the flow rate of chemical fire extinguishing agent is:

[0105] ;

[0106] Where:

[0107] Q 化 —Volume flow rate of liquid chemical fire extinguishing agent at normal temperature and pressure, m 3 / min;

[0108] ρ—Density of liquid chemical fire extinguishing agent at normal temperature and pressure, kg / m 3 ;

[0109] C—Volume extinguishing concentration of chemical fire extinguishing agent for low boiling point flammable liquid fire, %;

[0110] S—Specific volume of superheated steam of chemical fire extinguishing agent at 101KPa atmospheric pressure and test temperature, unit: m 3 / kg;

[0111] k1—correction coefficient, which is taken as 1.0 under normal conditions;

[0112] k1 is related to the altitude of the operating environment and can be adjusted according to the ratio of the air pressure at the altitude to the standard atmospheric pressure;

[0113] k2—redundancy coefficient, ranging from 1.1 to 90;

[0114] In step S3, the gas-liquid ratio of the high-stable compressed air foam is not less than 5:1, the foam supply intensity is 5L / (min·m2)~30L / (min·m2), and the calculation formula of the foam supply time t3 is:

[0115] ;

[0116] Where:

[0117] t1—fire control, temperature reduction, and bubble supply time, min;

[0118] t2—Bubble supply time to extinguish open flame, min;

[0119] t3—anti-reignition protection bubble supply time, min.

[0120] Compared with the prior art, the technical solution provided by this application has unique beneficial effects.

[0121] 1. The present invention adopts a positive pressure multi-agent combined foaming method, and produces different types of foams "compressed air foam-chemical gas / air mixed gas foam-chemical gas foam" in stages, giving full play to the high-efficiency fire control performance and excellent cooling performance of high-stable compressed air foam for low-boiling point flammable liquid fires, and the significant technical advantages of chemical gas foam for fast and efficient fire extinguishing of oil vapor residual fires, and realizing "fire control and cooling-extinguishing open flames-anti-reignition protection" in stages and layers. Economical and efficient fire extinguishing and protection, effectively solves the problems of single ordinary foam fire extinguishing technology for low-boiling point flammable liquid fires, long fire extinguishing time, weak ability, and inability to quickly and completely extinguish low-boiling point flammable liquid oil vapor residual fires, and the existing clean chemical gas foam fire extinguishing technology. Poor environmental protection, high cost, and insufficient fire extinguishing inhibition effect on large oil tank fires, solves the problem of low-boiling point flammable liquid fire extinguishing.

[0122] 2. The present invention utilizes the waste heat energy of the hot air of the screw air compressor and the hot oil of the compressor to heat and vaporize the liquid chemical fire extinguishing agents with different boiling points and vaporization characteristics in two stages, thereby realizing the rapid and complete vaporization of different liquid chemical fire extinguishing agents and ensuring the foaming performance and chemical inhibition performance of the foam based on the liquid chemical fire extinguishing agent. It not only fully utilizes the role of the air compressor facilities and saves resources, but also solves the problems of the prior art of poor foaming effect, inability to fully exert the chemical inhibition effect, and insufficient fire extinguishing efficiency when injected into the foam mixture in liquid form.

[0123] 3. The present invention can generate different types of foams, such as compressed air foam, chemical gas / air mixed gas foam, and chemical gas foam, respectively, and realizes the flexible regulation of "physical fire extinguishing" and "physical-chemical dual fire extinguishing". It can quickly control typical low-boiling point flammable liquid fires, continuously cool them down, and quickly extinguish the residual fire of oil vapor, thereby completely extinguishing low-boiling point flammable liquid storage tank fires. It has the outstanding characteristics of fast fire control and extinguishing speed, strong cooling and cooling ability, excellent anti-reignition performance, green environmental protection, and economical and efficient. It solves the problems of high cost, poor environmental protection, and inability to quickly extinguish large low-boiling point flammable liquid fires in the prior art. It is suitable for fixed fire extinguishing systems and mobile fire extinguishing equipment, and provides advanced and efficient fire extinguishing means for the technical problems of low-boiling point flammable liquid storage tank fire fighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0124] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0125] in:

[0126] Figure 1 A schematic diagram of the structure of a positive pressure multi-agent combined foam fire extinguishing system in one embodiment;

[0127] Figure 2 It is a schematic diagram of the structure of a mixed gas supply device of a positive pressure multi-agent combined foam fire extinguishing system in one embodiment;

[0128] Figure 3 A schematic diagram of the structure of a foam proportioning mixer of a positive pressure multi-agent combined foam fire extinguishing system in one embodiment;

[0129] Figure 4 It is a structural schematic diagram of a heat exchanger of a positive pressure multi-agent combined foam fire extinguishing system in one embodiment;

[0130] Figure 5 A schematic diagram of the structure of a chemical fire extinguishing agent-air mixer of a positive pressure multi-agent combined foam fire extinguishing system in one embodiment;

[0131] Figure 6 The present invention is a flow chart of the application method of a positive pressure multi-agent combined foam fire extinguishing system.

[0132] Reference numerals:

[0133] 1. Fire water tank; 1-1. Water supply valve; 2. Water supply valve; 3. Fire water pump;

[0134] 4. Foam proportion mixing device; 4-1. Foam liquid tank; 4-2. Liquid replenishing valve; 4-3. Liquid supply valve; 4-4. Foam liquid pump; 4-5. Foam liquid flow meter;

[0135] 5. Foam mixed liquid flow meter; 6. Liquid flow regulating valve;

[0136] 7. Mixed gas supply device; 7-1. Screw air compressor; 7-1-1. Compressor head; 7-1-2. Oil-gas separator; 7-1-3. Pressure regulating valve; 7-1-4. Hot air pipe; 7-1-5. Compressor hot oil pipe; 7-1-6. Compressor cold oil pipe;

[0137] 7-2, chemical fire extinguishing agent tank; 7-3, main control valve; 7-4, positive displacement pump; 7-5, liquid chemical fire extinguishing agent pipe;

[0138] 7-6, first heat exchanger; 7-6-1, inner tube; 7-6-2, outer tube; 7-6-3, medium inlet; 7-6-4, chemical fire extinguishing agent inlet; 7-6-5, medium outlet; 7-6-6, chemical fire extinguishing agent outlet;

[0139] 7-7A, first temperature sensor; 7-7B, second temperature sensor; 7-8, chemical fire extinguishing agent delivery pipeline; 7-9, first control valve; 7-10, second control valve; 7-11, second heat exchanger; 7-12, gaseous chemical fire extinguishing agent pipe; 7-13, third control valve;

[0140] 7-14, hot oil cooler; 7-15, cooling fan; 7-16, air cooler; 7-17, buffer gas tank; 7-18, air flow meter; 7-19, air flow regulating valve; 7-20, first one-way valve; 7-21, second one-way valve;

[0141] 7-22, chemical fire extinguishing agent air mixer; 7-22-1, outer wall; 7-22-2, inner core; 7-22-3, chemical fire extinguishing agent chamber; 7-22-4, air chamber; 7-22-5, mixed gas chamber; 7-22-6, first inlet; 7-22-7, second inlet; 7-22-8, air inlet; 7-22-9, mixed gas outlet; 7-22-10, dispersion hole; 7-23, third one-way valve;

[0142] 8. Gas-liquid mixer; 9. Central controller; 10. Foam release device. DETAILED DESCRIPTION

[0143] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of this application.

[0144] The present application provides a low-boiling-point flammable liquid storage tank fire extinguishing system and method.

[0145] like Figure 1 As shown, the overall structure of the positive pressure multi-agent foam fire extinguishing system is shown.

[0146] A positive pressure multi-agent combined foam fire extinguishing system, comprising a fire water tank 1, a water supply valve 2, a fire water pump 3, a foam proportion mixing device 4, a foam mixed liquid flow meter 5, a liquid flow regulating valve 6, a mixed gas supply device 7, a gas-liquid mixer 8, a central controller 9 and a foam release device 10;

[0147] The fire water tank 1 is connected to a fire water pump 3 through a pipeline, and a water supply valve 2 is provided on the pipeline to control the water supply; the fire water tank 1 also has a water replenishment valve 1-1.

[0148] The output end of the fire water pump 3 is connected to the foam mixture flow meter 5 through a pipeline;

[0149] The foam proportion mixing device 4 is connected to the foam mixed liquid flow meter 5 through a pipeline;

[0150] In the pipeline in front of the foam mixed liquid flow meter 5, the water pumped out by the fire water pump 3 and the foam liquid output by the foam proportion mixing device 4 are mixed, and the flow rate passing through is calculated by the mixed liquid flow meter;

[0151] The mixed liquid flow meter is connected to the inlet of the liquid flow regulating valve 6 through a pipeline, the outlet of the liquid flow regulating valve 6 is connected to an inlet of the gas-liquid mixer 8, and the outlet of the gas-liquid mixer 8 is connected to the foam release device 10.

[0152] Another inlet of the gas-liquid mixer 8 is also connected to a mixed gas supply device 7.

[0153] The central controller 9 is simultaneously connected to the foam proportion mixing device 4, the foam mixed liquid flow meter 5, the liquid flow regulating valve 6 and the mixed gas supply device 7 through wires or wirelessly, and detects and controls them.

[0154] The mixed gas supply device 7 provides a chemical fire extinguishing agent-air mixed gas containing a gaseous chemical fire extinguishing agent. The proportion of the gaseous chemical fire extinguishing agent in the mixed gas provided by the mixed gas supply device 7 can be adjusted in real time. The mixed gas supply device 7 accurately controls the proportion of the mixed gas injected into the foam mixed liquid in real time according to the size of the foam mixed liquid flow meter 5.

[0155] The chemical fire extinguishing agent is in liquid state at normal temperature and pressure.

[0156] The foam mixed liquid and the mixed gas in the gas-liquid mixer 8 are fully mixed and foamed to form fire extinguishing foam with both physical and chemical suppression functions, which is transported to the foam release device 10 through a pipeline.

[0157] like Figure 3 As shown, the structural relationship of the foam proportioner is shown.

[0158] The foam proportioning device 4 comprises a foam liquid tank 4-1, the foam liquid tank 4-1 is provided with a liquid replenishing valve 4-2, the foam liquid tank 4-1 is connected to a foam liquid pump 4-4 through a pipeline, a liquid supply valve 4-3 is provided on the pipeline, the outlet of the foam liquid pump 4-4 is connected to a foam liquid flow meter 4-5, and the outlet of the foam liquid flow meter 4-5 is connected to a foam mixed liquid flow meter 5 through a pipeline;

[0159] The foam liquid pump 4 - 4 and the foam liquid flow meter 4 - 5 are both connected to the central controller 9 via wires or wirelessly.

[0160] The central controller 9 adjusts the rotation speed of the foam liquid pump 4 - 4 according to the size of the foam mixed liquid flow meter 5 , thereby controlling the foam mixing ratio.

[0161] The foam proportion mixing device 4 controls the proportion of the foam liquid injected into the fire water in real time and accurately according to the size of the foam mixed liquid flow meter 5.

[0162] The foam proportioning device 4 may also be an existing pressure-type foam proportioning mixer or a balanced foam proportioning mixer.

[0163] like Figure 2 , the details of the structure of the mixed gas supply device 7 are shown.

[0164] The mixed gas supply device 7 includes a screw air compressor 7-1, a chemical fire extinguishing agent storage device, a vaporization device, a cooling system and a chemical fire extinguishing agent air mixer 7-22.

[0165] The screw air compressor 7-1 is used as an air source to provide air, and the chemical fire extinguishing agent supplied from the chemical fire extinguishing agent storage device is vaporized through the vaporization device by utilizing the residual heat of the screw air compressor 7-1;

[0166] The hot air exhausted from the screw air compressor 7 - 1 is cooled by the cooling system, fully mixed with the vaporized chemical fire extinguishing agent in the chemical fire extinguishing agent air mixer 7 - 22 , and injected into the gas-liquid mixer 8 .

[0167] The screw air compressor 7-1 includes a compressor head 7-1-1. After the air is compressed by the compressor head 7-1-1, the air contained therein is separated by an oil-gas separator 7-1-2, and the hot air passes through a pressure regulating valve 7-1-3 and a hot air pipe 7-1-4 into a vaporizing device;

[0168] The compressor hot oil is connected to the vaporization device through the compressor hot oil pipe 7-1-5, and then cooled by the cooling device and returned to the screw air compressor 7-1 through the compressor cold oil pipe 7-1-6.

[0169] The chemical fire extinguishing agent storage device includes a chemical fire extinguishing agent tank 7-2, which is connected to a main control valve 7-3, which is connected to a volume pump 7-4, and the pumped chemical fire extinguishing agent is connected to a vaporizing device through a liquid chemical fire extinguishing agent pipe 7-5.

[0170] like Figure 2 , 4 As shown, the implementation structure of the heat exchanger and the connection relationship between the various functional components connected thereto are shown.

[0171] The main body of the vaporization device is a heat exchanger.

[0172] The heat exchanger includes an inner tube 7-6-1 and an outer tube 7-6-2; the outer tube 7-6-2 wraps the inner tube 7-6-1, and the inner tube 7-6-1 and the outer tube 7-6-2 are connected by welding or flange sealing;

[0173] The outer tube 7-6-2 is provided with a chemical fire extinguishing agent inlet 7-6-4 and a chemical fire extinguishing agent outlet 7-6-6;

[0174] The inner tube 7-6-1 is provided with a medium inlet 7-6-3 and a medium outlet 7-6-5 at both ends;

[0175] Chemical extinguishing agent enters between the outer tube 7-6-2 and the inner tube 7-6-1; medium passes through the inner tube 7-6-1;

[0176] Through the heat exchange of the heat exchanger, the heat of the medium is transferred to the chemical fire extinguishing agent to heat and vaporize the chemical fire extinguishing agent.

[0177] The specific temperature value of the chemical fire extinguishing agent in the pipeline is related to the boiling point and volatility of the chemical fire extinguishing agent, and the specific temperature value may range from the boiling point of the chemical fire extinguishing agent to (the boiling point of the chemical fire extinguishing agent + 50°C).

[0178] The total length of the inner tube 7-6-1 and the outer tube 7-6-2 of the heat exchanger is determined according to the boiling point and volatility of the chemical extinguishing agent.

[0179] The heat exchanger includes a first heat exchanger 7-6 and a second heat exchanger 7-11;

[0180] The inner tube 7-6-1 of the first heat exchanger 7-6 transports hot air and has a length ranging from 0.5m to 10m.

[0181] The inner tube 7-6-1 of the second heat exchanger 7-11 transports the compressor hot oil and has a length ranging from 0.2m to 8m.

[0182] The chemical fire extinguishing agent inlet 7-6-4 of the first heat exchanger 7-6 is connected to the liquid chemical fire extinguishing agent pipe 7-5;

[0183] The chemical extinguishing agent outlet 7-6-6 of the first heat exchanger 7-6 is connected to the first inlet 7-22-6 of the chemical extinguishing agent air mixer 7-22 through a pipeline;

[0184] A first temperature sensor 7-7A and a first control valve 7-9 are provided on the pipeline between the chemical extinguishing agent outlet 7-6-6 of the first heat exchanger 7-6 and the chemical extinguishing agent air mixer 7-22;

[0185] The medium inlet 7-6-3 of the first heat exchanger 7-6 is connected to the hot air pipe 7-1-4;

[0186] The medium outlet 7-6-5 of the first heat exchanger 7-6 is connected to the cooling system to further cool the hot air and finally input it into the chemical extinguishing agent air mixer 7-22;

[0187] A chemical fire extinguishing agent delivery pipeline 7-8 is also connected to the pipeline between the first temperature sensor 7-7A and the first control valve 7-9;

[0188] The chemical fire extinguishing agent delivery pipeline 7-8 is connected to the chemical fire extinguishing agent inlet 7-6-4 of the second heat exchanger 7-11, and a second control valve 7-10 is provided on the chemical fire extinguishing agent delivery pipeline 7-8;

[0189] The chemical extinguishing agent outlet 7-6-6 of the second heat exchanger 7-11 is connected to the second inlet 7-22-7 of the chemical extinguishing agent air mixer 7-22 through the gaseous chemical extinguishing agent pipe 7-12;

[0190] A second temperature sensor 7-7B and a third control valve 7-13 are provided on the pipeline between the chemical extinguishing agent outlet 7-6-6 of the second heat exchanger 7-11 and the chemical extinguishing agent air mixer 7-22;

[0191] The medium inlet 7-6-3 of the second heat exchanger 7-11 is connected to the hot air pipe 7-1-4;

[0192] The medium outlet 7-6-5 of the second heat exchanger 7-11 is connected to the cooling system to further cool the hot air and finally input it into the chemical extinguishing agent air mixer 7-22;

[0193] The cooling system includes a hot oil cooler 7-14, a cooling fan 7-15, an air cooler 7-16, a buffer gas tank 7-17, an air flow meter 7-18 and an air flow regulating valve 7-19;

[0194] One end of the hot oil cooler 7-14 is connected to the medium outlet 7-6-5 of the second heat exchanger 7-11, and the other end is connected to the compressor cooling oil pipe 7-1-6;

[0195] One end of the air cooler 7-16 is connected to the medium outlet 7-6-5 of the first heat exchanger 7-6, and the other end is connected to the buffer gas tank 7-17.

[0196] The outlet of the buffer tank is connected to the air inlet 7-22-8 of the chemical fire extinguishing agent air mixer 7-22.

[0197] An air flow meter 7-18 and an air flow regulating valve 7-19 are provided on the connecting pipe between the buffer tank and the chemical fire extinguishing agent air mixer 7-22;

[0198] A cooling fan 7-15 is provided on one side of the hot oil cooler 7-14 and the air cooler 7-16.

[0199] like Figure 5 As shown; the structure of the chemical fire extinguishing agent air mixer 7-22 is shown.

[0200] The chemical extinguishing agent air mixer 7-22 comprises an outer wall 7-22-1 and an inner core 7-22-2;

[0201] The outer wall 7-22-1 forms a cross-shaped cavity, which is respectively provided with a first inlet 7-22-6, a second inlet 7-22-7, an air inlet 7-22-8 and a mixed gas outlet 7-22-9;

[0202] The first inlet 7-22-6 and the second inlet 7-22-7 are arranged opposite to each other, and the air inlet 7-22-8 and the mixed gas outlet 7-22-9 are arranged opposite to each other;

[0203] An inner core 7-22-2 is provided inside the first inlet 7-22-6 and the second inlet 7-22-7, and a dispersion hole 7-22-10 is provided on the inner core 7-22-2;

[0204] The inner core 7-22-2 divides the cross-shaped cavity into a chemical extinguishing agent chamber 7-22-3, an air chamber 7-22-4 and a mixed gas chamber 7-22-5;

[0205] The injected chemical fire extinguishing agent is ejected through the dispersion holes 7-22-10 on the inner core 7-22-2 and mixed with the air flowing into the air chamber 7-22-4 to be fully mixed in the mixed gas chamber 7-22-5, and then injected into the gas-liquid mixer 8 through the mixed gas outlet 7-22-9;

[0206] The first inlet 7-22-6, the second inlet 7-22-7, and the mixed gas outlet 7-22-9 are respectively provided with a first one-way valve 7-20, a second one-way valve 7-21 and a third one-way valve 7-23 to prevent gas backflow.

[0207] The number of the dispersed holes 7-22-10 is 3 to 50, and the hole diameter is 0.1 mm to 3 mm.

[0208] When in use, the volumetric pump 7-4 pumps out the chemical fire extinguishing agent, and the liquid chemical fire extinguishing agent exchanges heat with the hot air in the first heat exchanger 7-6. The gaseous chemical fire extinguishing agent after heating and vaporization is output from the chemical fire extinguishing agent outlet 7-6-6.

[0209] A first temperature sensor 7-7A is provided at the chemical extinguishing agent outlet 7-6-6 to monitor the temperature of the chemical extinguishing agent in the pipeline to determine whether the chemical extinguishing agent has exceeded its boiling point and is completely vaporized. If the temperature of the chemical extinguishing agent in the pipeline exceeds a specific temperature value, the first control valve 7-9 is opened and the second control valve 7-10 is closed, and the gaseous chemical extinguishing agent is directly injected into the chemical extinguishing agent air mixer 7-22 through the first inlet 7-22-6 to be fully mixed with the air to form a mixed gas;

[0210] If the temperature of the chemical fire extinguishing agent in the pipeline is lower than a specific temperature value, the second control valve 7-10 is opened. At this time, the first control valve 7-9 is closed and the third control valve 7-13 is opened, and the chemical fire extinguishing agent that is not completely vaporized is passed into the second heat exchanger 7-11 for further heating and vaporization. A second temperature sensor 7-7B is respectively arranged on the chemical fire extinguishing agent outlet 7-6-6 pipeline of the second heat exchanger 7-11. The gaseous chemical fire extinguishing agent that is fully heated and vaporized by the second heat exchanger 7-11 is injected into the chemical fire extinguishing agent air mixer 7-22 through the second inlet 7-22-7 to be fully mixed with the air to form a mixed gas; the second temperature sensor 7-7B is used to monitor the temperature of the gaseous chemical fire extinguishing agent in the pipeline in real time.

[0211] The hot air in the oil-gas separator 7-1-2 of the screw air compressor 7-1 is passed into the medium inlet 7-6-3 of the first heat exchanger 7-6 through the pressure regulating valve 7-1-3. The air cooled by the first heat exchanger 7-6 is injected into the air cooler 7-16 for further cooling and then transported to the buffer gas tank 7-17, and then passed into the chemical fire extinguishing agent air mixer 7-22 through the air flow meter 7-18 and the air flow regulating valve 7-19.

[0212] The compressor hot oil in the oil-gas separator 7-1-2 of the screw air compressor 7-1 passes through the second heat exchanger 7-11 and the hot oil cooler 7-14 respectively, and then is injected into the compressor head 7-1-1.

[0213] By utilizing the waste heat energy of the hot air of the screw air compressor 7-1 and the hot oil of the compressor, the liquid chemical fire extinguishing agent is heated and vaporized in two stages, so as to realize the rapid and complete vaporization of the liquid chemical fire extinguishing agent with different boiling points and vaporization characteristics. For example, for the liquid chemical fire extinguishing agent with a low boiling point and easy to vaporize, only the waste heat energy of the hot air of the screw air compressor 7-1 can realize rapid and complete vaporization, and then heat exchange is only performed in the first heat exchanger 7-6, and after vaporization, the gaseous chemical fire extinguishing agent is directly injected into the chemical fire extinguishing agent air mixer 7-22 through the first inlet 7-22-6 through the control valve, and is fully mixed with the air to form a mixed gas; for the liquid chemical fire extinguishing agent with a high boiling point and difficult to vaporize, it is fully heated and vaporized in the first heat exchanger 7-6 and the second heat exchanger 7-11 successively, and then the gaseous chemical fire extinguishing agent is injected into the chemical fire extinguishing agent air mixer 7-22 through the second inlet 7-22-7, and is fully mixed with the air to form a mixed gas.

[0214] The volume pump 7-4, the control valve, the first temperature sensor 7-7A, the second temperature sensor 7-7B, the first control valve 7-9, the second control valve 7-10, the third control valve 7-13, the air flow meter 7-18, and the air flow regulating valve 7-19 are connected to the central controller 9 via signal lines or wirelessly.

[0215] The volumetric pump 7-4 automatically adjusts the rotation speed according to the flow rate of the air flow meter 7-18, thereby controlling the output flow rate of the liquid chemical fire extinguishing agent.

[0216] The central controller 9 is controlled by PLC or other automated methods.

[0217] The foam releasing device 10 is a non-air-suction foam releasing device 10, which can be a foam cannon, a foam gun, a foam nozzle, or a foam spray pipe.

[0218] The foam fire extinguishing agent adopts water film-forming foam fire extinguishing agent, protein foam fire extinguishing agent, anti-solvent foam fire extinguishing agent, fluorine-free foam fire extinguishing agent and other types of foam fire extinguishing agents.

[0219] The chemical fire extinguishing agent adopts brominated trifluoropropylene or perfluorohexanone or heptafluorocyclopentane or other types of new high-boiling-point environmentally friendly and efficient chemical gas fire extinguishing agents, and the boiling point is higher than 25°C.

[0220] In parallel with the development of the above-mentioned fire extinguishing system, a positive pressure multi-agent combined foam fire extinguishing system application method was designed, and the specific steps include:

[0221] S1. Control fire and cool down

[0222] For fires in low-boiling-point flammable liquid storage tanks, highly stable compressed air foam is generated and applied. The excellent fire control and extinguishing properties, thermal insulation protection properties and efficient cooling properties of highly stable compressed air foam are utilized to quickly control the low-boiling-point flammable liquid fire, and a foam blanket with a thickness of not less than 100mm is formed on the surface of the low-boiling-point flammable liquid to gradually cool down the liquid until it drops below the boiling point of the low-boiling-point flammable liquid, leaving only the residual fire of oil vapor on the surface of the foam blanket.

[0223] The gas-liquid ratio of the high-stable compressed air foam is not less than 5:1, and the foam supply intensity is 5L / (min·m 2 )~30L / (min·m 2 ), the calculation formula for the minimum bubble supply time of compressed air foam is:

[0224] ;

[0225] Where:

[0226] t1—minimum bubble supply time for fire control and temperature reduction, min;

[0227] h0—the amount of compressed air foam for initial fire control dissipation, mm. It is determined according to the possible fire scale of the protected object. The larger the fire scale, the higher the value of the compressed air foam for initial fire control dissipation. The minimum value is not less than 50mm;

[0228] h—thickness of compressed air foam blanket, mm, not less than 100 mm;

[0229] q—foam supply intensity, L / (min·m 2 );

[0230] x—gas-liquid ratio.

[0231] S2. Extinguish open fire

[0232] For the residual fire of low-boiling-point flammable liquid oil vapor on the surface of the foam blanket, chemical gas-air mixed gas foam or chemical gas foam is generated and applied to quickly and completely extinguish the residual fire of oil vapor on the surface of the foam blanket by chemical inhibition;

[0233] During the chemical gas-air mixed gas foam fire extinguishing process, the determining factor for whether the chemical inhibition effect can be exerted lies in whether the chemical fire extinguishing agent can be successfully vaporized and reach the fire extinguishing concentration in the bubbles of the foam. The most ideal situation is that the fire extinguishing concentration is reached both in the bubbles of the foam blanket and 200 mm above the foam blanket.

[0234] The chemical gas-air mixed gas foam supply intensity is 8L / (min·m 2 )~30L / (min·m2 ), the gas-liquid ratio is not less than 1:1, the foam supply time t2 is 3min~30min, and the calculation formula of the foam mixture and air flow is:

[0235] ;

[0236] ;

[0237] Where:

[0238] Q 液 —Volume flow rate of foam mixture, m 3 / min;

[0239] Q 空 —Compressed air volume flow, m 3 / min;

[0240] A—protected area, m 2 ;

[0241] A—protected area, m 2 ;

[0242] q—foam supply intensity, L / (min·m 2 );

[0243] x—gas-liquid ratio.

[0244] The calculation formula for the flow rate of chemical fire extinguishing agent is:

[0245] ;

[0246] Where:

[0247] Q 化 —Volume flow rate of liquid chemical fire extinguishing agent at normal temperature and pressure, m 3 / min;

[0248] ρ—Density of liquid chemical fire extinguishing agent at normal temperature and pressure, kg / m 3 ;

[0249] C—Volume extinguishing concentration of chemical fire extinguishing agent for low boiling point flammable liquid fire, %;

[0250] S—Specific volume of superheated steam of chemical fire extinguishing agent at 101KPa atmospheric pressure and test temperature, unit: m 3 / kg;

[0251] k1—correction coefficient, which can be taken as 1.0 under general conditions;

[0252] k1 is related to the altitude of the operating environment and can be adjusted according to the ratio of the air pressure at the altitude to the standard atmospheric pressure.

[0253] k2—redundancy coefficient, ranging from 1.1 to 90.

[0254] S3, Anti-reignition protection

[0255] After the fire of low-boiling-point flammable liquid storage tank is completely extinguished, continue to apply high-stability compressed air foam for 1min~30min, maintain a 200-500mm foam blanket on the surface of low-boiling-point flammable liquid to keep it cool and effectively prevent re-ignition;

[0256] The gas-liquid ratio of the highly stable compressed air foam is not less than 5:1, the foam supply intensity is 5L / (min·m2)~30L / (min·m2), and the calculation formula of the foam supply time t3 is:

[0257] ;

[0258] Where:

[0259] t1—fire control, temperature reduction, and bubble supply time, min;

[0260] t2—Bubble supply time to extinguish open flame, min;

[0261] t3—anti-reignition protection bubble supply time, min.

[0262] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0263] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A positive pressure multi-agent foam fire extinguishing system, characterized in that: Including: fire water tank, water supply valve, fire water pump, foam proportion mixing device, foam mixed liquid flow meter, liquid flow regulating valve, mixed gas supply device, gas-liquid mixer, central controller and foam release device; The fire water tank is connected to the fire water pump through a pipeline, and a water supply valve is provided on the pipeline to control the water supply; the fire water tank is also provided with a water supply valve; The output end of the fire water pump is connected to the foam mixture flow meter through a pipeline; The foam proportion mixing device is connected to the foam mixed liquid flow meter through a pipeline; In the pipeline in front of the foam mixed liquid flowmeter, the water pumped out by the fire pump and the foam liquid output by the foam proportion mixing device are mixed, and the flow rate passing through is calculated by the mixed liquid flowmeter; The mixed liquid flow meter is connected to the inlet of the liquid flow regulating valve through a pipeline, the outlet of the liquid flow regulating valve is connected to an inlet of the gas-liquid mixer, and the outlet of the gas-liquid mixer is connected to the foam release device; Another inlet of the gas-liquid mixer is also connected to a mixed gas supply device; The central controller is simultaneously connected to the foam proportion mixing device, the foam mixed liquid flow meter, the liquid flow regulating valve and the mixed gas supply device through wires or wirelessly, and detects and controls them; The mixed gas supply device provides a chemical fire extinguishing agent-air mixed gas containing a gaseous chemical fire extinguishing agent, the proportion of the gaseous chemical fire extinguishing agent in the mixed gas provided by the mixed gas supply device can be adjusted in real time, and the mixed gas supply device accurately controls the proportion of the mixed gas injected into the foam mixed liquid in real time according to the size of the foam mixed liquid flow meter; The gas-liquid mixer fully mixes the foam mixed liquid and the mixed gas to foam, forming a fire extinguishing foam with both physical and chemical inhibition functions, which is transported to the foam release device through a pipeline.

2. The positive pressure multi-agent foam fire extinguishing system according to claim 1 is characterized in that: The foam proportioning device comprises a foam liquid tank, the foam liquid tank is provided with a liquid replenishing valve, the foam liquid tank is connected to a foam liquid pump through a pipeline, a liquid supply valve is arranged on the pipeline, the outlet of the foam liquid pump is connected to a foam liquid flow meter, and the outlet of the foam liquid flow meter is connected to a foam mixed liquid flow meter through a pipeline; The foam liquid pump and the foam liquid flow meter are connected to the central controller via wires or wirelessly; The central controller adjusts the rotation speed of the foam liquid pump according to the size of the foam mixed liquid flow meter, thereby controlling the foam mixing ratio; The foam proportion mixing device accurately controls the proportion of foam liquid injected into the fire water in real time according to the size of the foam mixed liquid flow meter; The foam proportioning device may also adopt an existing pressure-type foam proportioning mixer or a balanced foam proportioning mixer.

3. The positive pressure multi-agent foam fire extinguishing system according to claim 2 is characterized in that: The mixed gas supply device includes a screw air compressor, a chemical fire extinguishing agent storage device, a vaporizing device, a cooling system and a chemical fire extinguishing agent air mixer; The screw air compressor is used as an air source to provide air, and the chemical fire extinguishing agent supplied from the chemical fire extinguishing agent storage device is vaporized through the vaporization device using the waste heat of the screw air compressor; The hot air discharged from the screw air compressor is cooled by the cooling system, fully mixed with the vaporized chemical fire extinguishing agent in the chemical fire extinguishing agent air mixer, and injected into the gas-liquid mixer; The screw air compressor includes a compressor head. After the air is compressed by the compressor head, the contained air is separated by an oil-gas separator, and the hot air passes through a pressure regulating valve and a hot air pipe into a vaporizing device; The hot oil of the compressor is connected to the vaporization device through the compressor hot oil pipe, and then it is cooled by the cooling device and then returned to the screw air compressor through the compressor cold oil pipe; The chemical fire extinguishing agent storage device comprises a chemical fire extinguishing agent tank, the chemical fire extinguishing agent tank is connected to a main control valve, the main control valve is connected to a volumetric pump, and the pumped chemical fire extinguishing agent is connected to a vaporizing device through a liquid chemical fire extinguishing agent pipe.

4. The positive pressure multi-agent combined foam fire extinguishing system according to claim 3 is characterized in that: The main body of the vaporization device is a heat exchanger. The heat exchanger comprises an inner tube and an outer tube; the outer tube wraps the inner tube, and the inner tube and the outer tube are connected by welding or flange sealing; The outer tube is provided with a chemical fire extinguishing agent inlet and a chemical fire extinguishing agent outlet; Both ends of the inner tube are respectively provided with a medium inlet and a medium outlet; A chemical fire extinguishing agent passes between the outer tube and the inner tube; a medium passes through the inner tube; Through the heat exchange of the heat exchanger, the heat of the medium is transferred to the chemical fire extinguishing agent to heat and vaporize the chemical fire extinguishing agent; The specific temperature value of the chemical fire extinguishing agent in the pipeline is related to the boiling point and volatility of the chemical fire extinguishing agent, and the specific temperature value may range from the boiling point of the chemical fire extinguishing agent to 50° C. above the boiling point of the chemical fire extinguishing agent.

5. The positive pressure multi-agent foam fire extinguishing system according to claim 4 is characterized in that: The total length of the inner and outer tubes of the heat exchanger is determined according to the boiling point and volatility of the chemical fire extinguishing agent; The heat exchanger comprises a first heat exchanger and a second heat exchanger; The inner tube of the first heat exchanger conveys hot air and has a length ranging from 0.5m to 10m; The inner tube of the second heat exchanger conveys the compressor hot oil, and the length ranges from 0.2m to 8m; The chemical fire extinguishing agent inlet of the first heat exchanger is connected to the liquid chemical fire extinguishing agent pipe; The chemical fire extinguishing agent outlet of the first heat exchanger is connected to the first inlet of the chemical fire extinguishing agent air mixer through a pipeline; A first temperature sensor and a first control valve are arranged on the pipeline between the chemical fire extinguishing agent outlet of the first heat exchanger and the chemical fire extinguishing agent air mixer; The medium inlet of the first heat exchanger is connected to the hot air pipe; The medium outlet of the first heat exchanger is connected to a cooling system to further cool the hot air and finally input it into a chemical fire extinguishing agent air mixer; A chemical fire extinguishing agent delivery pipeline is also connected to the pipeline between the first temperature sensor and the first control valve; The chemical fire extinguishing agent delivery pipeline is connected to the chemical fire extinguishing agent inlet of the second heat exchanger, and a second control valve is arranged on the chemical fire extinguishing agent delivery pipeline; The chemical extinguishing agent outlet of the second heat exchanger is connected to the second inlet of the chemical extinguishing agent air mixer through a gaseous chemical extinguishing agent pipe; A second temperature sensor and a third control valve are provided on the pipeline between the chemical fire extinguishing agent outlet of the second heat exchanger and the chemical fire extinguishing agent air mixer; The medium inlet of the second heat exchanger is connected to the hot air pipe; The medium outlet of the second heat exchanger is connected to the cooling system to further cool the hot air and finally input it into the chemical fire extinguishing agent air mixer; A first temperature sensor is arranged at the outlet of the chemical fire extinguishing agent to monitor the temperature of the chemical fire extinguishing agent in the pipeline to determine whether the chemical fire extinguishing agent has exceeded its boiling point and is completely vaporized. If the temperature of the chemical fire extinguishing agent in the pipeline exceeds a specific temperature value, the first control valve is opened and the second control valve is closed at this time, and the gaseous chemical fire extinguishing agent is directly injected into the chemical fire extinguishing agent air mixer through the first inlet to be fully mixed with the air to form a mixed gas; If the temperature of the chemical fire extinguishing agent in the pipeline is lower than a specific temperature value, the second control valve is opened. At this time, the first control valve is closed and the third control valve is opened, and the chemical fire extinguishing agent that is not completely vaporized is passed into the second heat exchanger for further heating and vaporization. A second temperature sensor is respectively arranged on the chemical fire extinguishing agent outlet pipeline of the second heat exchanger. The gaseous chemical fire extinguishing agent that is fully heated and vaporized by the second heat exchanger is injected into the chemical fire extinguishing agent air mixer through the second inlet to be fully mixed with the air to form a mixed gas; the second temperature sensor is used to monitor the temperature of the gaseous chemical fire extinguishing agent in the pipeline in real time.

6. The positive pressure multi-agent foam fire extinguishing system according to claim 5 is characterized in that: The cooling system includes a hot oil cooler, a cooling fan, an air cooler, a buffer gas tank, an air flow meter and an air flow regulating valve; One end of the hot oil cooler is connected to the medium outlet of the second heat exchanger, and the other end is connected to the compressor cold oil pipe; One end of the air cooler is connected to the medium outlet of the first heat exchanger, and the other end is connected to the buffer gas tank; The outlet of the buffer tank is connected to the air inlet of the chemical fire extinguishing agent air mixer; An air flow meter and an air flow regulating valve are arranged on the connecting pipe between the buffer tank and the chemical fire extinguishing agent air mixer; A cooling fan is provided on one side of the hot oil cooler and the air cooler.

7. The positive pressure multi-agent foam fire extinguishing system according to claim 6 is characterized in that: The chemical fire extinguishing agent air mixer comprises an outer wall and an inner core; The outer wall forms a cross-shaped cavity, which is respectively provided with a first inlet, a second inlet, an air inlet and a mixed gas outlet; The first inlet and the second inlet are arranged opposite to each other, and the air inlet and the mixed gas outlet are arranged opposite to each other; An inner core is arranged inside the first inlet and the second inlet, and a dispersion hole is arranged on the inner core; The inner core divides the cross-shaped cavity into a chemical fire extinguishing agent chamber, an air chamber and a mixed gas chamber; The injected chemical fire extinguishing agent is ejected through the dispersion holes on the inner core and mixed with the air flowing into the air chamber to be fully mixed in the mixed gas chamber, and then injected into the gas-liquid mixer through the mixed gas outlet; A first one-way valve, a second one-way valve and a third one-way valve are respectively provided at the first inlet, the second inlet and the mixed gas outlet to prevent gas backflow; The number of the dispersed holes is 3 to 50, and the hole diameter is 0.1 mm to 3 mm.

8. The positive pressure multi-agent foam fire extinguishing system according to claim 7 is characterized in that: The hot air in the oil-gas separator of the screw air compressor is introduced into the medium inlet of the first heat exchanger through the pressure regulating valve, the air cooled by the first heat exchanger is injected into the air cooler for further cooling and then transported to the buffer gas tank, and then introduced into the chemical fire extinguishing agent air mixer through the air flow meter and the air flow regulating valve; The compressor hot oil in the oil-gas separator of the screw air compressor is respectively passed through the second heat exchanger and the hot oil cooler, and then injected into the compressor head; The waste heat energy of the hot air from the screw air compressor and the hot oil from the compressor is used to heat and vaporize the liquid chemical fire extinguishing agent in two stages, so that the liquid chemical fire extinguishing agent with different boiling points and vaporization characteristics can be quickly and completely vaporized. The volume pump, control valve, first temperature sensor, second temperature sensor, first control valve, second control valve, third control valve, air flow meter, and air flow regulating valve are connected to the central controller via signal lines or wirelessly. The volumetric pump automatically adjusts the rotation speed according to the flow rate of the air flow meter, thereby controlling the output flow rate of the liquid chemical fire extinguishing agent; The central controller is controlled by PLC or other automation methods; The foam release device adopts a non-air-suction foam release device, which can adopt a foam cannon, a foam gun, a foam nozzle or a foam spray pipe; The foam fire extinguishing agent is a water film-forming foam fire extinguishing agent, a protein foam fire extinguishing agent, an anti-solvent foam fire extinguishing agent, or a fluorine-free foam fire extinguishing agent; The chemical fire extinguishing agent adopts a high-boiling-point environmentally friendly and efficient chemical gas fire extinguishing agent, and the boiling point is higher than 25°C.

9. A positive pressure multi-agent foam fire extinguishing system application method, characterized in that: Using the positive pressure multi-agent combined foam fire extinguishing system as described in any one of claims 1 to 8, the steps include: S1, fire control and temperature reduction; For low-boiling-point flammable liquid storage tank fires, highly stable compressed air foam is generated and applied to quickly control the low-boiling-point flammable liquid fire, and a foam blanket with a thickness of not less than 100mm is formed on the surface of the low-boiling-point flammable liquid to gradually cool the liquid down until it drops below the boiling point of the low-boiling-point flammable liquid, leaving only the residual fire of oil vapor on the surface of the foam blanket; S2, extinguish open fire; For the residual fire of low-boiling-point flammable liquid oil vapor on the surface of the foam blanket, chemical gas-air mixed gas foam or chemical gas foam is generated and applied to quickly and completely extinguish the residual fire of oil vapor on the surface of the foam blanket by chemical inhibition; During the chemical gas-air mixed gas foam fire extinguishing process, the chemical fire extinguishing agent can be successfully vaporized and reach a fire extinguishing concentration in the bubbles of the foam; S3, anti-reignition protection; After the fire in the low-boiling point flammable liquid storage tank is completely extinguished, continue to apply high-stable compressed air foam for 1min~30min, maintain a 200-500mm foam blanket on the surface of the low-boiling point flammable liquid to keep it cooled and effectively prevent re-ignition.

10. The application method of the positive pressure multi-agent combined foam fire extinguishing system according to claim 9, characterized in that: The gas-liquid ratio of the high-stability compressed air foam in step S1 is not less than 5:1, and the foam supply intensity is 5L / (min·m 2 )~30L / (min·m 2 ), the calculation formula for the minimum bubble supply time of compressed air foam is: ； Where: t1—minimum bubble supply time for fire control and temperature reduction, min; h0—the amount of compressed air foam for initial fire control dissipation, mm; it is determined according to the possible fire scale of the protected object. The larger the fire scale, the higher the value of the compressed air foam for initial fire control dissipation, and the minimum value is not less than 50mm; h—thickness of compressed air foam blanket, mm, not less than 100 mm; q—foam supply intensity, L / (min·m 2 ); x—gas-liquid ratio; In step S2, the chemical gas-air mixed gas foam supply intensity is 8L / (min·m 2 )~30L / (min·m 2 ), the gas-liquid ratio is not less than 1:1, the foam supply time t2 is 3min~30min, and the calculation formula of the foam mixture and air flow is: ； ； Where: Q 液 —Volume flow rate of foam mixture, m 3 / min; Q 空 —Compressed air volume flow, m 3 / min; A—protected area, m 2 ; A—protected area, m 2 ; q—foam supply intensity, L / (min·m 2 ); x—gas-liquid ratio; The calculation formula for the flow rate of chemical fire extinguishing agent is: ； Where: Q 化 —Volume flow rate of liquid chemical fire extinguishing agent at normal temperature and pressure, m 3 / min; ρ—Density of liquid chemical fire extinguishing agent at normal temperature and pressure, kg / m 3 ; C—Volume extinguishing concentration of chemical fire extinguishing agent for low boiling point flammable liquid fire, %; S—Specific volume of superheated steam of chemical fire extinguishing agent at 101KPa atmospheric pressure and test temperature, unit: m 3 / kg; k1—correction coefficient, which is taken as 1.0 under normal conditions; k1 is related to the altitude of the operating environment and can be adjusted according to the ratio of the air pressure at the altitude to the standard atmospheric pressure; k2—redundancy coefficient, ranging from 1.1 to 90; In step S3, the gas-liquid ratio of the high-stable compressed air foam is not less than 5:1, the foam supply intensity is 5L / (min·m2)~30L / (min·m2), and the calculation formula of the foam supply time t3 is: ； Where: t1—fire control, temperature reduction, and bubble supply time, min; t2—Bubble supply time to extinguish open flame, min; t3—anti-reignition protection bubble supply time, min.

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