Fire extinguishing agent for flammable liquid storage tank fire and its application, storage and recovery method

Abstract

The present invention discloses a fire extinguishing agent for flammable liquid storage tank fires and a method for dispensing, storing and recovering the fire extinguishing agent. The fire extinguishing agent is a solid particulate fire extinguishing agent, and the density of the solid particulate fire extinguishing agent is determined according to the density of the flammable liquid; the diameter of the solid particulate fire extinguishing agent is determined according to the viscosity of the flammable liquid and the diameter of the storage tank. The present invention uses a solid substance that is resistant to high temperatures and insoluble in flammable liquids to make a large number of granular spherical objects with a lower density than the flammable liquid. At the beginning of a storage tank fire, the granular spherical objects are injected into the storage tank, and quickly and evenly spread and accumulate on the surface of the flammable liquid, thereby reducing or even blocking the contact between the flammable liquid and the air, and reducing the upper reaction heat conduction or radiation to the flammable liquid. At the same time, when used in conjunction with a foam fire extinguishing agent, the effects of reducing the fire in the storage tank, reducing the fire and extinguishing the fire are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid fire extinguishing, and in particular to a fire extinguishing agent for flammable liquid storage tank fires and a method for dispensing, storing and recovering the fire extinguishing agent. Background Art

[0002] A large number of flammable liquid storage tanks are used in production and life. At present, there are three main types of flammable liquid storage tanks at home and abroad, including dome tanks, internal floating roof tanks, and external floating roof tanks. These flammable liquid storage tanks may cause full liquid surface fires when they meet certain conditions.

[0003] At present, there are few technical equipments with full liquid surface fire extinguishing capability at home and abroad. The two sets of American Williams high-flow remote fire extinguishing systems equipped by the National Dangerous Chemicals Emergency Rescue Sinochem Zhoushan Team are capable of extinguishing 100,000 m 3 The capacity of crude oil storage tanks. However, the system has a huge demand for water, and the equipment itself is expensive. Most flammable liquid storage tanks in China are not equipped with this fire extinguishing equipment. Therefore, when a full liquid surface fire occurs in storage tanks in other regions of the country, especially in crude oil external floating roof storage tanks, the only option is to wait for the medium in the tank to burn out, and cool and protect the equipment and facilities around the burning tank to prevent the fire from further expanding. Faced with such a situation, some researchers have explored some methods to prevent crude oil from boiling over and reduce the probability of full liquid surface fires. For example, the Tianjin Fire Department's invention patent for "A method for using a hollow metal ball for auxiliary fire extinguishing of a full liquid surface fire in a storage tank" designs a hollow metal ball. According to the density of the liquid fuel, the outer diameter, wall thickness, yield strength and other parameters of the metal ball are designed to greatly suppress the flame of the liquid pool fire; Sinopec Qingdao Angong Institute's "Fire prevention and control and fire suppression methods for petrochemical storage tanks" designs a polygonal floating plate made of flame-retardant and refractory materials, and controls the number of floating plates to ensure that at least 80% of the liquid surface in the petrochemical storage tank is covered, thereby effectively reducing the risk of full liquid surface fire in the petrochemical storage tank; Swiss TRELLEBORG company invented a "Dry Foam" product, which reduces the volatilization of VOCs and the probability of liquid boiling by suppressing 98% of steam. However, except for the "Dry Foam" product, the others are only in the design and development stage and have not formed products that can be used in the market. Due to its high price, the "Dry Foam" product has not been widely used after it was put on the market in 2015.

[0004] The problems with current technology are: first, at present, the large-flow remote fire extinguishing system has the ability to extinguish full-surface fires in storage tanks to a certain extent, but the equipment has harsh operating conditions and must ensure that a large amount of water can be continuously provided. This cannot be used in areas where water is insufficient. In addition, the equipment is expensive. Even if it can meet the water demand, it cannot be guaranteed that every risk area is equipped. Second, the theoretical research foundation for the methods currently provided by several institutions to reduce the probability of full-surface fires of flammable liquids is relatively weak, and it mainly focuses on the selection of materials and shapes (spheres and regular polyhedrons). However, no research has been conducted on how to select the most suitable materials and particle sizes according to the properties of flammable liquids, how to store particles, release particles, how many particles to release, and how to evaluate the relationship between the release amount of particles and fire extinguishing efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a fire extinguishing agent for flammable liquid storage tank fires and its application, storage and recovery methods, and to study the storage and application of solid particulate fire extinguishing agent particles, the number of particles to be applied, and the relationship between the application amount and the fire extinguishing efficiency according to the properties of the flammable liquid. A low-density granular fire extinguishing agent is made of a solid substance that is resistant to high temperatures and insoluble in flammable liquids. When a large-area fire occurs in the storage tank, it is applied to the liquid surface of the storage tank by mechanical throwing, pipeline transportation, etc., to reduce the burning liquid surface area or block the contact between the flammable liquid and the air, thereby achieving the effect of reducing the fire or blocking the fire.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A fire extinguishing agent for flammable liquid storage tank fire, the fire extinguishing agent is a solid particulate fire extinguishing agent,

[0008] The density of the solid particulate fire extinguishing agent is determined based on the density of the flammable liquid;

[0009] The diameter of the solid particulate fire extinguishing agent is determined according to the viscosity of the flammable liquid and the diameter of the storage tank.

[0010] Preferably, the melting point of the material used to prepare the solid particulate fire extinguishing agent is higher than or equal to the temperature at the root of the flame of the flammable liquid that continues to burn.

[0011] Preferably, the diameter of the solid particulate fire extinguishing agent is 2 mm to 160 mm; the ratio of the diameter of the flammable liquid storage tank to the diameter of the solid particulate fire extinguishing agent is 500 to 2000.

[0012] Preferably, the minimum density of the solid particulate fire extinguishing agent satisfies: being able to withstand a wind speed of 3.3 m / s;

[0013] The maximum density of the solid particulate fire extinguishing agent satisfies: when the maximum cross-section of a single layer of solid particulate fire extinguishing agent is in the same plane as the liquid surface.

[0014] Preferably, the solid particulate fire extinguishing agent is a solid sphere or a hollow sphere, wherein the melting point of the solid particulate fire extinguishing agent is higher than or equal to the temperature of the root of the flame of the flammable liquid that continues to burn.

[0015] Preferably, the hollow spherical solid particulate fire extinguishing agent is filled with air or a low-density substance that is stable at high temperatures;

[0016] The pressure on the outside of the solid particulate fire extinguishing agent is not less than 1.6 MPa, and the pressure on the inside of the hollow sphere solid particulate fire extinguishing agent is not less than 0.5 MPa.

[0017] Preferably, the wall thickness of the hollow sphere solid particulate fire extinguishing agent is determined according to the following formula:

[0018]

[0019] Where: δ is the wall thickness; R is the radius of the solid particulate fire extinguishing agent; ρ is the density of the solid particulate fire extinguishing agent; ρ1 is the density of the solid particulate fire extinguishing agent filling material; ρ2 is the density of the solid particulate fire extinguishing agent spherical material.

[0020] A method for applying a fire extinguishing agent for a flammable liquid storage tank fire comprises: applying the above-mentioned solid particulate fire extinguishing agent to the surface of the flammable liquid.

[0021] Preferably, the solid particulate fire extinguishing agent has a diameter of 2 mm to 160 mm;

[0022] The solid particulate fire extinguishing agent is used in a single particle size or a mixture of multiple particle sizes.

[0023] Preferably, the solid particulate fire extinguishing agent is used alone or in combination with an existing foam fire extinguishing agent and applied to the surface of the flammable liquid;

[0024] The solid particulate fire extinguishing agent can be reused.

[0025] Preferably, the solid particulate fire extinguishing agent is delivered by mechanical spraying above the liquid, continuous pipeline transportation or underwater pipeline injection; or,

[0026] The solid particulate fire extinguishing agent is packaged into fixed amount release units using easily soluble materials;

[0027] The easily soluble material can dissolve at the boiling point of the flammable liquid and release solid particulate fire extinguishing agent to disperse on the surface of the flammable liquid.

[0028] Preferably, when the flammable liquid is stored normally, the number of layers of the solid particulate fire extinguishing agent is designed according to the volatility suppression rate η of the gas on the surface of the flammable liquid, wherein:

[0029] η=(C 0 -C n ) / C 0

[0030] Where η is the volatile inhibition rate of the flammable liquid surface, C 0 C is the concentration of volatile gas on the surface of flammable liquid when no solid particulate fire extinguishing agent is laid; n The volatile concentration of gas on the surface of flammable liquid when n layers of solid particulate fire extinguishing agent are laid. n represents the number of layers of solid particulate fire extinguishing agent laid on the surface of flammable liquid, n=1, 2, 3...

[0031] Preferably, when a flammable liquid catches fire, the solid particulate fire extinguishing agent is combined with a spray foam fire extinguishing agent of the same spray intensity and applied to the surface of the flammable liquid in a layer design, specifically:

[0032] The calculation formula for the solid particulate fire extinguishing agent used for laying one layer is as follows:

[0033]

[0034] Where: q is the number of single-layer solid microparticle fire extinguishing agents, R 0 is the radius of the tank, R is the radius of the solid particulate fire extinguishing agent;

[0035] The fire extinguishing efficiency of laying n layers is:

[0036] w=(T 0 -T n )T 0

[0037] Where w is the fire extinguishing efficiency of solid particulate fire extinguishing agent laid in n layers; T 0 The time it takes for the foam fire extinguishing agent to extinguish the fire; T n Lay n layers of solid particulate fire extinguishing agent, where n represents the number of layers of solid particulate fire extinguishing agent laid, n=1, 2, 3...

[0038] Preferably, the maximum layer M of the solid particulate fire extinguishing agent in a storage tank on fire is calculated as follows:

[0039]

[0040] Where: q is the number of single-layer solid microparticle fire extinguishing agents, t 0 is the time required from the occurrence of fire in the tank to the occurrence of boiling over in the tank, v is the batch delivery rate of solid particulate fire extinguishing agent, and M is the maximum solid particulate fire extinguishing agent layer laid;

[0041]

[0042] Where x is the effective delivery efficiency, M is the maximum solid particulate fire extinguishing agent layer laid, and n is the number of solid particulate fire extinguishing agents laid when the fire extinguishing efficiency w is optimal.

[0043] A method for storing and recovering fire extinguishing agents for flammable liquid storage tank fires, such as the above-mentioned method for storing and recovering solid particulate fire extinguishing agents.

[0044] Preferably, the solid particulate fire extinguishing agent is stored in a steel storage tank; the mesh size of the filter device of the outlet pipeline of the steel storage tank matches the particle size of the solid particulate fire extinguishing agent, so that the solid particulate fire extinguishing agent can be recovered.

[0045] Preferably, the reserve amount of the solid particulate fire extinguishing agent is greater than 1.5 times the theoretical demand;

[0046] The theoretical demand calculation formula is as follows:

[0047] Q=q×M

[0048] In the formula: Q is the theoretical reserve, q is the single-layer laying volume, and M is the maximum number of laying layers.

[0049] Technical effects and advantages of the present invention:

[0050] The present invention uses a solid substance that is resistant to high temperatures and insoluble in flammable liquids to produce a large number of granular spherical objects with a lower density than the flammable liquid. At the early stage of a tank fire, the granular spherical objects are injected into the tank and quickly and evenly spread and accumulate on the surface of the flammable liquid, thereby reducing or even blocking the contact between the flammable liquid and the air, and reducing the heat conduction or radiation of the upper reaction to the flammable liquid. At the same time, when used in conjunction with a foam fire extinguishing agent, the effects of reducing tank fire, reducing fire intensity and extinguishing fire are achieved.

[0051] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flame retardant and fire extinguishing principle diagram of the solid particulate fire extinguishing agent of the present invention;

[0053] Figure 2 It is a cross-sectional view of a hollow spherical solid particulate fire extinguishing agent according to a specific embodiment of the present invention;

[0054] Figure 3 It is a cross-sectional view of a solid spherical solid particulate fire extinguishing agent according to a specific embodiment of the present invention;

[0055] Figure 4 It is a schematic diagram of mechanically throwing solid particulate fire extinguishing agent according to a specific embodiment of the present invention;

[0056] Figure 5 It is a schematic diagram of a liquid injection pipeline continuously conveying a solid particulate fire extinguishing agent according to a specific embodiment of the present invention;

[0057] Figure 6 This is a schematic diagram of a submerged injection pipeline continuously conveying a solid particulate fire extinguishing agent according to a specific embodiment of the present invention;

[0058] Figure 7 This is a schematic diagram of the centralized unit releasing solid particulate fire extinguishing agent according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] In order to solve the shortcomings of the prior art, the present invention discloses a fire extinguishing agent for flammable liquid storage tank fires and a method for dispensing, storing and recovering the fire extinguishing agent. The fire extinguishing agent is a solid particulate fire extinguishing agent, and the density of the solid particulate fire extinguishing agent is designed according to the density of the flammable liquid; the diameter of the solid particulate fire extinguishing agent is designed according to the viscosity of the flammable liquid and the diameter of the storage tank, and the melting point of the material for preparing the solid particulate fire extinguishing agent is higher than or equal to the temperature of the root of the flame of the continuous combustion of the flammable liquid.

[0061] Furthermore, the diameter of the solid particulate fire extinguishing agent is designed to be between 2 mm and 160 mm. The solid particulate fire extinguishing agent can be of a single particle size or a mixture of multiple particle sizes.

[0062] The recommended ratio of the tank diameter to the solid particulate fire extinguishing agent diameter is between 500 and 2000, which has a better fire extinguishing effect. The higher the viscosity of the flammable liquid, the smaller the diameter ratio selection range, which can be expressed by the formula: A = D / d, where A is the diameter ratio; D is the tank diameter, in meters; d is the diameter of the particulate fire extinguishing agent, in meters.

[0063] Furthermore, the optimal density of the solid particulate fire extinguishing agent should be designed with reference to the density of the flammable liquid, which is conducive to the uniform laying of the solid particulate fire extinguishing agent on the liquid surface, and its density needs to meet the following conditions: the minimum density of the solid particulate fire extinguishing agent is the density when it can withstand a wind speed of 3.3m / s without being blown away; the maximum density of the solid particulate fire extinguishing agent is the density of a single layer of solid particulate fire extinguishing agent when the maximum cross-section is in the same plane as the liquid surface, as follows,

[0064] First, the minimum density of the solid microparticle fire extinguishing agent is determined through experiments. It needs to be able to withstand a wind speed of 3.3m / s (annual average wind speed, excluding special circumstances of strong winds). When it is not blown away, the density of the solid microparticle fire extinguishing agent is its minimum design density. Since the wind resistance of the solid microparticle fire extinguishing agent is not only related to its density, but also to its size, at the beginning of the design of the solid microparticle fire extinguishing agent, after determining the diameter of the solid microparticle fire extinguishing agent, its minimum density is determined through experiments (placing multiple solid microparticle fire extinguishing agents on a stable plane, blowing them in the horizontal direction of the ball with a wind speed of 3.3m / s, and ensuring that the solid microparticle fire extinguishing agents remain motionless).

[0065] Second, the maximum density of the solid microparticle fire extinguishing agent. The maximum density of the single-layer solid microparticle fire extinguishing agent must ensure that the maximum cross-section is in the same plane as the liquid surface. According to the fact that the gravity G on the solid microparticle fire extinguishing agent is equal to the buoyancy Ffloat on the solid microparticle fire extinguishing agent, and Ffloat = pliquid gvpush, pliquid is the density of the flammable liquid, and vpush is the volume of the microparticles immersed in the liquid, which is half of the volume of the microparticles. Therefore, G = vmicroparticle gρmicroparticle = ρliquid gvpush, ρmicroparticle = 1 / 2ρliquid, that is, when the density of the microparticles is half of the density of the flammable liquid, it can be ensured that the maximum interface of the microparticles is in the same plane as the liquid surface.

[0066] Special solid particulate fire extinguishing agent, considering the needs of conventional gasoline to crude oil, the recommended range of solid particulate fire extinguishing agent is 0.35-0.5g / cm 3 . Universal solid particulate fire extinguishing agent, the optimal density is 0.42±0.02g / cm 3 .

[0067] Furthermore, the material used to prepare the solid particulate fire extinguishing agent should meet the requirements of high temperature resistance, pressure resistance, oleophobicity, and hydrophilicity. The high temperature resistance of the material used to prepare the solid particulate fire extinguishing agent should be compatible with the combustion temperature of the flammable liquid, and should be higher than or equal to the temperature at the root of the flame of the flammable liquid that continues to burn. For example, the melting point of the metal material of the solid particulate fire extinguishing agent used for crude oil fires in atmospheric pressure storage tanks should be higher than 1200°C, the melting point of the metal material of the solid particulate fire extinguishing agent used for gasoline fires should be higher than 1000°C, and the melting point of the metal material of the solid particulate fire extinguishing agent used for kerosene fires should be higher than 1100°C. Figure 2 and Figure 3It can be seen that the solid particulate fire extinguishing agent of the present invention is a solid sphere or a hollow sphere. In the case of a solid sphere solid particulate fire extinguishing agent, the whole is made of a high-temperature resistant, low-density non-metallic material. Exemplarily, the non-metallic material is a nickel alloy, a chromium alloy, etc.; the shell of the hollow sphere solid particulate fire extinguishing agent is a high-temperature resistant metal material or a non-metallic material, and the interior of the sphere is filled with air or a low-density substance that is stable at high temperatures. Exemplarily, the low-density substance is a nickel alloy, a chromium alloy or glass microspheres, alumina hollow spheres or perlite, etc.

[0068] Furthermore, the hollow sphere solid particulate fire extinguishing agent is filled with air or a low-density substance that is stable at high temperatures; the solid particulate fire extinguishing agent is subjected to a pressure of not less than 1.6 MPa on the outside, and the hollow sphere solid particulate fire extinguishing agent is subjected to a pressure of not less than 0.5 MPa on the inside.

[0069] The reasons are as follows: when the solid particulate fire extinguishing agent is filled with air, the internal pressure of the particles is 1atm at room temperature. According to the ideal gas state equation PV=nRT (p refers to the pressure of the ideal gas, V is the volume of the ideal gas, n represents the amount of ideal gas substance, and T represents the thermodynamic temperature of the ideal gas, and R is the ideal gas constant), when n, R, and V inside the solid particulate fire extinguishing agent remain unchanged, the internal gas pressure increases with the increase of the external ambient temperature, and the two are directly proportional.

[0070] The hollow spherical solid particulate fire extinguishing agent is filled with a low-density substance that is stable at high temperatures;

[0071] Designed based on the combustion temperature of flammable liquids at 1200°C, the maximum pressure that the particles can withstand inside is about 5atm (0.5Mpa). In addition, when the solid particle fire extinguishing agent is transported by a pump, it needs to withstand a large external pressure. This patent combines the working pressure of a general pump to design the maximum external pressure of the solid particle fire extinguishing agent to be 1.6Mpa.

[0072] Furthermore, for the optimal wall thickness design of the hollow sphere solid particulate fire extinguishing agent, after determining the overall density of the solid particulate fire extinguishing agent, the density of the sphere material and the density of the internal filling material are known, and the wall thickness formula is calculated as follows:

[0073]

[0074] Where: δ is the wall thickness; R is the radius of the solid particulate fire extinguishing agent; ρ is the density of the solid particulate fire extinguishing agent; ρ1 is the density of the solid particulate fire extinguishing agent filling material; ρ2 is the density of the solid particulate fire extinguishing agent spherical material.

[0075] The wall thickness algorithm of the solid particulate fire extinguishing agent is established on the basis that the wall thickness satisfies the above strength constraints (the maximum internal pressure of the sphere is greater than 0.6 MPa, and the maximum external pressure of the sphere is greater than 1.6 MPa).

[0076] The present invention also provides a method for applying a fire extinguishing agent to a flammable liquid storage tank, the method comprising applying a solid microparticle fire extinguishing agent to the surface of the flammable liquid, wherein the diameter of the solid microparticle fire extinguishing agent used for application is 2 mm to 160 mm; the solid microparticle fire extinguishing agent is a single particle size or a mixture of multiple particle sizes.

[0077] Furthermore, combined with Figure 1 It can be seen that when a fire occurs in flammable liquid, a solid particulate fire extinguishing agent is laid on the surface of the flammable liquid to form a flame retardant zone, and the upper layer of the flame retardant zone is the vaporization zone (volatile gas of the flammable liquid) and the flame zone in sequence; the flame retardant zone is formed by the accumulation of solid particles on the surface of the burning liquid, which weakens the heating and evaporation effect of the flame on the liquid and reduces the amount of burning material until the flame is extinguished.

[0078] The solid particulate fire extinguishing agent can also be used in combination with an existing foam fire extinguishing agent and applied together to the surface of the flammable liquid. The foam fills the pores between the solid particles, thereby increasing the effect of isolating the air and reducing the effects of heat conduction and radiation.

[0079] like Figure 4-6 As shown, the solid particles used in the solid particle fire extinguishing agent isolation fire extinguishing method are delivered by mechanical spraying above the liquid, continuous pipeline transportation (multiple pipelines can be laid at the same time according to actual conditions), and injection into the submerged pipeline. Figure 4 , use a powerful pump to mechanically sprinkle solid particulate fire extinguishing agent at a suitable angle, and the particulate fire extinguishing agent quickly forms a uniform layer on the surface of the flammable liquid. Figure 5 , lay a pipe with a diameter greater than 20cm on the surface of the tank, use the pipe to transport the particulate fire extinguishing agent from above the tank into the tank, and form a quick laying layer on the surface of the liquid, such as Figure 6 , a pipe with a diameter greater than 20 cm is laid on the inner surface of the tank, and the particulate fire extinguishing agent is transported from the bottom of the tank into the tank through the pipe, and a quick laying layer is formed on the surface of the liquid. Or, Figure 7 The solid particulate fire extinguishing agent shown is packaged into fixed-amount dispensing units using easily soluble materials, and the fixed-amount dispensing units are packaged into any one of the forms of spheres, ellipsoids, cubes or cuboids; the easily soluble material melts on the surface of the high-temperature packaging material, can dissolve at the boiling point of the flammable liquid, and release the stored solid particulate fire extinguishing agent, which is spread evenly on the surface of the flammable liquid and dispersed.

[0080] The number of layers of the solid particulate fire extinguishing agent of the present invention is designed as follows:

[0081] The number of layers refers to the ratio between the amount of solid microparticle fire extinguishing agent applied and the amount of solid microparticle fire extinguishing agent theoretically required to cover the flammable liquid fire area. The minimum effective fire isolation layer refers to the minimum number of layers of solid microparticle fire extinguishing agent required to continuously and evenly deliver solid microparticle fire extinguishing agent and evenly lay it on the surface of the flammable liquid until the fire is extinguished when a flammable liquid catches fire.

[0082] The number of laying layers is determined by multiple factors, mainly involving three reference quantities: the flammable liquid surface volatility inhibition rate η, the fire extinguishing efficiency w and the effective delivery efficiency x.

[0083] Furthermore, the solid particulate fire extinguishing agent, after being laid on the surface of the flammable liquid before the flammable liquid catches fire, has an inhibitory effect on the volatilization of the gas on its surface, effectively preventing the occurrence of the flammable liquid fire. The degree of inhibition is characterized by the flammable liquid surface inhibition volatility rate η. Through experiments, the number of layers laid when the optimal surface inhibition volatility rate is achieved can be obtained (which can be a decimal).

[0084] The test method is as follows: In a confined space (100m*100m*20m), use an oil and gas concentration detection device to monitor the concentration of a flammable liquid in a 10m 3 Gas volatile concentration C of the storage tank 0 During monitoring, the detection device needs to be placed 5 cm from the surface of the flammable liquid; a layer of a solid particulate fire extinguishing agent is laid on the surface of the flammable liquid, and the gas volatile concentration C on the surface of the flammable liquid is repeatedly measured after stabilization for 20 minutes. 1 , and so on, laying the second layer C 2 ...lay n layers of C n .

[0085] When the flammable liquid is stored normally, the volatilization inhibition η of the solid particulate fire extinguishing agent laid in n layers is,

[0086] η=(C 0 -C n ) / C 0

[0087] Where η is the volatile inhibition rate of the flammable liquid surface, C 0 It is the concentration of volatile gas on the surface of flammable liquid when no solid particulate fire extinguishing agent is laid; C n The volatile concentration of gas on the surface of flammable liquid when n layers of solid particulate fire extinguishing agent are laid. n represents the number of layers of solid particulate fire extinguishing agent laid on the surface of flammable liquid, n=1, 2, 3...

[0088] Furthermore, when a flammable liquid catches fire, the solid particulate fire extinguishing agent, after being laid on the surface of the flammable liquid, is used in conjunction with a foam fire extinguishing agent to effectively shorten the fire extinguishing time, and the degree of this shortening is characterized by the fire extinguishing efficiency w. Through experiments, the number of layers laid to achieve the highest fire extinguishing efficiency can be obtained.

[0089] The test method is as follows: In a confined space (100m*100m*20m), a cylindrical tank with a diameter of 1m containing sufficient flammable liquid is ignited. The time taken to extinguish the fire using foam fire extinguishing agent is T 0 , use the projection device to evenly release the solid particulate fire extinguishing agent into the storage tank, and the microspheres quickly form a uniform laying layer.

[0090] The calculation formula for the solid particulate fire extinguishing agent used for laying one layer is as follows:

[0091]

[0092] Where: q is the number of single-layer solid microparticle fire extinguishing agents, R 0 is the radius of the tank, R is the radius of the solid particulate fire extinguishing agent;

[0093] At this time, the foam fire extinguishing agent is sprayed with the same spray intensity, and the time required for extinguishing the fire is T 1 , and so on, lay the second layer, T 2 ...lay n layers, T n Until no continuous flame can be formed, then the fire extinguishing efficiency w of laying n layers is:

[0094] w=(T 0 -T n )T 0

[0095] Where w is the fire extinguishing efficiency of solid particulate fire extinguishing agent laid in n layers; T 0 The time it takes for the foam fire extinguishing agent to extinguish the fire; T n Lay n layers of solid particulate fire extinguishing agent, where n represents the number of layers of solid particulate fire extinguishing agent laid, n=1, 2, 3...

[0096] Furthermore, for a tank that is on fire, the number of layers of the solid particulate fire extinguishing agent to be laid is limited, that is, the laying of the solid particulate fire extinguishing agent must be completed during the process from the fire to the boiling of the tank. This process is characterized by the effective placement efficiency x. The time required from the fire to the boiling of the tank is t 0 (min), the batch delivery rate of solid microparticle fire extinguishing agent is v (pieces / min), and the maximum solid microparticle fire extinguishing agent layer M that can be laid before the tank boils over is calculated as follows:

[0097]

[0098] Where: q is the number of single-layer solid microparticle fire extinguishing agents, t 0is the time required from the occurrence of fire in the tank to the occurrence of boiling over in the tank, v is the batch delivery rate of solid particulate fire extinguishing agent, and M is the maximum solid particulate fire extinguishing agent layer laid;

[0099]

[0100] In the formula, x is the effective delivery efficiency, M is the maximum number of solid microparticle fire extinguishing agent layers laid, and n is the number of solid microparticle fire extinguishing agents laid when the fire extinguishing efficiency w is optimal. Only when x>1 can the optimal number of layers of solid microparticle fire extinguishing agents laid be less than the maximum number of layers laid to achieve the best fire extinguishing effect.

[0101] At present, the research on solid microparticle fire extinguishing agents in the prior art mostly remains in the research stage, and there is no research on the relationship between the release amount of solid microparticle fire extinguishing agents and the fire extinguishing efficiency. Although a small amount of solid microparticle fire extinguishing agents are put into use on the market, they are mainly used for storage in flammable liquid storage tanks. When extinguishing fires, they are mainly used in conjunction with fire extinguishing agents, and the efficiency is relatively low. The present invention realizes the design of solid microparticle fire extinguishing agents and the relationship between the release amount of solid microparticle fire extinguishing agents and the fire extinguishing efficiency through theoretical calculations. The quantitative release of solid microparticle fire extinguishing agents through theoretical calculations can not only improve the fire extinguishing efficiency, but also save costs.

[0102] The present invention also provides a method for storing and recovering a fire extinguishing agent for a flammable liquid storage tank, wherein the solid particulate fire extinguishing agent is stored in a steel storage tank; the mesh number of the filter device of the steel storage tank outlet pipeline matches the particle size of the solid particulate fire extinguishing agent, and the solid particulate fire extinguishing agent can be recovered.

[0103] Furthermore, the solid particulate fire extinguishing agent can be stored in a steel box that is convenient for loading, unloading and transportation.

[0104] Furthermore, the reserve amount of the solid particulate fire extinguishing agent is greater than 1.5 times the theoretical demand amount, taking into account the extreme situation of a fire in the largest storage tank in the tank area. The theoretical demand amount is calculated as follows:

[0105] Q=q×M

[0106] In the formula: Q is the theoretical reserve, q is the single-layer laying volume, and M is the maximum number of laying layers.

[0107] Furthermore, the solid particles used in the solid particle fire extinguishing agent isolation fire extinguishing method are not melted by fire or dissolved in liquid (flammable liquid or fire water), and the outlet pipeline of the flammable liquid storage tank using this method is installed with a filter device with a mesh size matching the particle size to recover the solid particles.

[0108] Furthermore, the solid particles used in the solid particle fire extinguishing agent isolation fire extinguishing method can be reused after cleaning.

[0109] The present invention will be further described below in conjunction with specific embodiments.

[0110] Volatility test

[0111] Step 1: Prepare 4 50mL round glass containers and weigh the mass of each glass container.

[0112] Step 2: Add 30 mL of diesel to a glass container. Weigh and calculate the mass of a certain crude oil in the container.

[0113] Step 3: Calculate the material B of the present invention or the comparative material A required to lay down 0 mm, 2 mm, 5 mm and 10 mm thickness in different beakers.

[0114] Step 4: Spread the weighed solid material into each glass container, place each beaker in a fume hood (strong ventilation) and keep it at a constant temperature (25°C) for 24h, 36h, 72h and 168h, respectively, weigh and calculate the mass of diesel remaining in the beaker after volatilization, and calculate the volatility inhibition rate (residual mass / total mass, %).

[0115] (3) Experimental results

[0116] Table 1 Comparison of volatility inhibition rate data

[0117]

[0118] According to Table 1, in the glass container without material, the volatility suppression rate of diesel is the worst, and the volatility reaches 65% at 168h; it can be seen from the comparative material A and the material B of the present invention that as the number of layers increases, the volatility suppression rate becomes better; the volatility suppression rate of the material B of the present invention when 5 layers of solid particulate fire extinguishing agent are laid is equivalent to the volatility suppression rate of the comparative material A when 10 layers of solid particulate fire extinguishing agent are laid, indicating that the volatility suppression rate of the material B of the present invention is better than that of the prior art material A.

[0119] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fire extinguishing agent for flammable liquid storage tank fires, It is characterized in that The fire extinguishing agent is a solid particulate fire extinguishing agent, The density of the solid particulate fire extinguishing agent is determined according to the density of the flammable liquid; wherein the ratio of the diameter of the flammable liquid storage tank to the diameter of the solid particulate fire extinguishing agent is 500-2000, and the particle size of the solid particulate fire extinguishing agent is a single particle size or a mixture of multiple particle sizes; The diameter of the solid particulate fire extinguishing agent is determined according to the viscosity of the flammable liquid and the diameter of the storage tank, wherein the minimum density of the solid particulate fire extinguishing agent satisfies: being able to withstand a wind speed of 3.3 m / s, The maximum density of the solid particulate fire extinguishing agent satisfies: when the maximum cross-section of a single layer of solid particulate fire extinguishing agent is in the same plane as the liquid surface, vparticleρparticle=ρliquidvrow, wherein pliquid is the density of the flammable liquid, vrow is the volume discharged by the particles immersed in the liquid, ρparticle is the density of the solid particulate fire extinguishing agent, and vparticle is the volume of the solid particulate fire extinguishing agent.

2. A fire extinguishing agent for flammable liquid storage tank fire according to claim 1, It is characterized in that The melting point of the material used to prepare the solid particulate fire extinguishing agent is higher than or equal to the temperature at the root of the flame of the flammable liquid that continues to burn.

3. A fire extinguishing agent for flammable liquid storage tank fire according to claim 1 or 2, It is characterized in that The solid particulate fire extinguishing agent has a diameter of 2 mm to 160 mm.

4. A fire extinguishing agent for flammable liquid storage tank fire according to claim 1, It is characterized in that The solid particulate fire extinguishing agent is a solid sphere or a hollow sphere, wherein the melting point of the solid particulate fire extinguishing agent is higher than or equal to the temperature of the root of the flame of the flammable liquid that continues to burn.

5. A fire extinguishing agent for flammable liquid storage tank fire according to claim 4, It is characterized in that The hollow spherical solid particulate fire extinguishing agent is filled with air or a low-density substance that is stable at high temperatures; The pressure on the outside of the solid particulate fire extinguishing agent is not less than 1.6 MPa, and the pressure on the inside of the hollow sphere solid particulate fire extinguishing agent is not less than 0.5 MPa.

6. A fire extinguishing agent for flammable liquid storage tank fire according to claim 5, It is characterized in that The wall thickness of the hollow sphere solid particulate fire extinguishing agent is determined according to the following formula: Where: δ is the wall thickness; R is the radius of the solid particulate fire extinguishing agent; ρ is the density of the solid particulate fire extinguishing agent; ρ1 is the density of the solid particulate fire extinguishing agent filling material; ρ2 is the density of the solid particulate fire extinguishing agent spherical material.

7. A method for applying a fire extinguishing agent for a flammable liquid storage tank fire, It is characterized in that include: Apply the solid particulate fire extinguishing agent as claimed in any one of claims 1 to 6 to the surface of the flammable liquid.

8. The method for applying the fire extinguishing agent for flammable liquid storage tank fire according to claim 7, It is characterized in that The diameter of the solid particulate fire extinguishing agent is 2mm~160mm; The solid particulate fire extinguishing agent is used in a single particle size or a mixture of multiple particle sizes.

9. The method for applying the fire extinguishing agent for flammable liquid storage tank fire according to claim 7 or 8, It is characterized in that The solid particulate fire extinguishing agent is used alone or in combination with an existing foam fire extinguishing agent and applied to the surface of the flammable liquid; The solid particulate fire extinguishing agent can be reused.

10. The method for applying the fire extinguishing agent for flammable liquid storage tank fire according to claim 7 or 8, It is characterized in that The solid particulate fire extinguishing agent is placed by mechanical spraying above the liquid, continuous pipeline transportation or underwater pipeline injection; or The solid particulate fire extinguishing agent is packaged into fixed amount release units using easily soluble materials; The easily soluble material can dissolve at the boiling point of the flammable liquid and release solid particulate fire extinguishing agent to disperse on the surface of the flammable liquid.

11. The method for applying a fire extinguishing agent for a flammable liquid storage tank fire according to claim 7, It is characterized in that When the flammable liquid is stored normally, the number of layers of the solid particulate fire extinguishing agent is designed according to the volatility suppression rate η of the gas on the surface of the flammable liquid, wherein: η=(C 0 -C n ) / C 0 Where η is the volatile inhibition rate of the flammable liquid surface, C 0 C is the concentration of volatile gas on the surface of flammable liquid when no solid particulate fire extinguishing agent is laid; n The volatile concentration of gas on the surface of flammable liquid when n layers of solid particulate fire extinguishing agent are laid. n represents the number of layers of solid particulate fire extinguishing agent laid on the surface of flammable liquid, n=1, 2, 3...

12. The method for applying a fire extinguishing agent for a flammable liquid storage tank fire according to claim 7, It is characterized in that When a flammable liquid catches fire, the solid particulate fire extinguishing agent is combined with a spray foam fire extinguishing agent of the same spray intensity and applied to the surface of the flammable liquid in a layer design, specifically: The calculation formula for the solid particulate fire extinguishing agent used for laying one layer is as follows: Where: q is the number of single-layer solid microparticle fire extinguishing agents, R 0 is the radius of the tank, R is the radius of the solid particulate fire extinguishing agent; The fire extinguishing efficiency of laying n layers is: w =(T 0 -T n )T 0 In the formula, w The fire extinguishing efficiency of laying n layers of solid particulate fire extinguishing agent; T 0 The time it takes for the foam fire extinguishing agent to extinguish the fire; T n Lay n layers of solid particulate fire extinguishing agent, where n represents the number of layers of solid particulate fire extinguishing agent laid, n=1, 2, 3...

13. The method for applying a fire extinguishing agent for a flammable liquid storage tank fire according to claim 12, It is characterized in that The maximum layer M of the solid particulate fire extinguishing agent in a tank on fire is calculated as follows: Where: q is the number of single-layer solid particulate fire extinguishing agents, t 0 The time required from the occurrence of fire in the tank to the occurrence of boiling over in the tank. v is the batch delivery rate of solid particulate fire extinguishing agent, M is the maximum solid particulate fire extinguishing agent layer laid; In the formula, x is the effective delivery efficiency, M is the maximum solid particulate fire extinguishing agent layer laid, and n is the fire extinguishing efficiency w The optimal amount of solid particulate fire extinguishing agent to be laid.

14. A method for storing and recovering fire extinguishing agents for flammable liquid storage tank fires, It is characterized in that A method for storing and recovering a solid particulate fire extinguishing agent as claimed in any one of claims 1 to 6.

15. The method for storing and recovering fire extinguishing agents for flammable liquid storage tank fires according to claim 14, It is characterized in that The solid particulate fire extinguishing agent is stored in a steel storage tank; the mesh number of the filter device of the outlet pipeline of the steel storage tank matches the particle size of the solid particulate fire extinguishing agent, and the solid particulate fire extinguishing agent can be recovered.

16. The method for storing and recovering fire extinguishing agents for flammable liquid storage tank fires according to claim 14, It is characterized in that The reserve amount of the solid particulate fire extinguishing agent is greater than 1.5 times the theoretical demand; The theoretical demand calculation formula is as follows: In the formula: Q is the theoretical reserve, q is the single-layer laying volume, and M is the maximum number of laying layers.

Images