An environment-friendly water film forming foam extinguishing agent suitable for transformer oil fire disposal

Abstract

The present application belongs to the field of fire extinguishing safety technology, and provides an environment-friendly water film forming foam extinguishing agent suitable for transformer oil fire disposal, which comprises the following components: 8wt%-22wt% of surfactant, 5wt%-15wt% of thickening agent, 10wt%-20wt% of antifreezing agent, 5wt%-8wt% of foam stabilizer, 0.5wt%-1wt% of preservative, and the balance of deionized water. The components involved in the present application are set according to the physicochemical properties of transformer oil, and can ensure the performance of rapid spreading when the actual foam liquid falls on the surface of the transformer oil. The raw materials used are non-toxic and degradable, and do not pollute the environment after use. In the present application, fly ash is used as the raw material of the foam stabilizer, which makes the waste particles of the power plant become valuable, and makes the foam have stronger oxygen isolation and anti-reignition performance than the traditional two-phase water film forming foam. The present application has excellent effects in cooling the fuel surface, blocking oxygen, inhibiting fuel evaporation and resisting reignition, and can be normally used under the condition that the air temperature is above-20 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of fire extinguishing safety technology, specifically relating to an environmentally friendly aqueous film-forming foam extinguishing agent suitable for handling transformer oil fires. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Aqueous film-forming foam (AFFF) fire extinguishing agents are named for their ability to spontaneously spread and form a dense water film on oil surfaces. This water film not only cools the fuel surface but also isolates oxygen and hinders fuel evaporation, extinguishing fires through mechanisms such as these. It is considered one of the most effective fire extinguishing agents for oil fires. The key component enabling the spontaneous spreading of this type of foam is a fluorosurfactant, which has extremely high surface activity, allowing the foam liquid to spread spontaneously under the drive of surface / interfacial tension. However, with the discovery of the toxicity and recalcitrant nature of PFOS generated during the production of fluorosurfactants, traditional long-chain fluorosurfactants have been gradually banned in developed countries. Currently, the development of environmentally friendly surfactants mainly relies on two technical routes: one is to eliminate the addition of fluorine-containing components, and the other is to use non-toxic short-chain surfactants to replace harmful components.

[0004] Existing patents and commercially available products already involve a large number of general-purpose aqueous film-forming foam (AFCF) fire extinguishing agents. Although surface / interfacial tension measurements according to current standards indicate that they all possess spreading and film-forming properties, the standard oils used in these standards actually differ significantly in physicochemical properties from different types of oils used in actual production and daily life. AFCF fire extinguishing agents with specific compositions cannot spontaneously spread on all oil surfaces. Experimental results show that some foaming agents, whose spreading coefficients calculated from surface / interfacial tension tests are much greater than 0, do not spontaneously spread when dripped onto transformer oil surfaces. This phenomenon occurs because some foaming liquids reduce the interfacial tension between the foaming liquid and transformer oil to 0, leading to oil-water miscibility and preventing the foaming liquid from spreading on the transformer oil surface. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an environmentally friendly aqueous film-forming foam (AFCF) fire extinguishing agent suitable for transformer oil fire suppression. It primarily solves three issues with existing AFCF solutions: inability to spontaneously spread on transformer oil surfaces, poor environmental performance, and insufficient resistance to reignition. This invention utilizes trace amounts of short-chain fluorinated surfactants and organosilicon surfactants as core components to propose an environmentally friendly AFCF fire extinguishing agent suitable for transformer oil fire suppression. This invention uses fly ash as a foam stabilizer, transforming waste particulate matter from thermal power plants into a valuable resource. This particulate foam stabilizer significantly extends the stabilization time of the extinguishing foam, giving it stronger oxygen-isolating and reignition-resistant properties.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides an environmentally friendly aqueous film-forming foam extinguishing agent suitable for handling transformer oil fires, the extinguishing agent being composed of the following raw materials in weight percentages: 8wt%-22wt% compound surfactant, 5wt%-15wt% thickener, 10wt%-20wt% antifreeze agent, 5wt%-8wt% foam stabilizer, 0.5wt%-1wt% preservative, with the balance being water;

[0008] The compound surfactant is composed of an organosilicon nonionic surfactant, a short fluorocarbon chain amphoteric surfactant, an anionic surfactant AOS, and an anionic surfactant SDS.

[0009] Studies have shown that fluorocarbon surfactants with a carbon chain length ≤ 4 are more prone to decomposition, at which point their environmental harm is negligible. However, short-chain fluorides generally have relatively poor surface activity; for example, sodium perfluorobutyl sulfonate has a critical micelle concentration (CMC) as high as 273 mmol·L⁻¹ in aqueous solution. -1 Furthermore, its surface tension (γCMC) is as high as 29.72 mN·m. -1 To this end, researchers have conducted extensive work on the synthesis of short-chain fluorocarbon surfactants. This invention proposes an environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression, using trace amounts of short-chain fluorosurfactants and organosilicon surfactants as core components. This invention ensures rapid spreading of the foam liquid upon impact with the transformer oil surface, thereby cooling the surface of combustible materials, isolating oxygen, and preventing the volatilization of combustibles.

[0010] Based on the aforementioned compound surfactants, thickeners, antifreeze agents, foam stabilizers, and preservatives, this invention also explores the compound surfactants, thickeners, and other components required for an environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression. Verification has shown that the foam extinguishing agent composition of this invention is tailored to the physicochemical properties of transformer oil, ensuring rapid spreading when the foam liquid falls onto the surface of the transformer oil, thereby cooling the surface of combustible materials, isolating oxygen, and preventing the volatilization of combustible materials.

[0011] Therefore, in order to provide an environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression, which can spontaneously spread on the surface of transformer oil, has excellent environmental performance, and excellent anti-burning and anti-reignition capabilities, this invention further investigates the proportions of the compound surfactant, thickener, antifreeze agent, foam stabilizer, and preservative. In some embodiments, the extinguishing agent is composed of the following raw materials by weight percentage: 20wt%-22wt% compound surfactant, 8wt%-15wt% thickener, 14wt%-15wt% antifreeze agent, 6wt%-8wt% foam stabilizer, 0.5wt% preservative, and the balance being water;

[0012] In some effective embodiments, the extinguishing agent is composed of the following raw materials by weight percentage: 20 wt% compound surfactant, 8 wt% thickener, 15 wt% antifreeze agent, 6 wt% foam stabilizer, 0.5 wt% preservative, and the balance being water;

[0013] In some effective embodiments, the extinguishing agent is composed of the following raw materials by weight percentage: 22 wt% compound surfactant, 15 wt% thickener, 8 wt% antifreeze, 8 wt% foam stabilizer, 0.5 wt% preservative, and the balance being water.

[0014] AFFF (Aqueous Film-Forming Foam) relies on low concentrations of fluorocarbon surfactants to reduce the surface tension of water, allowing the water to spread rapidly and form a film, thus more efficiently covering burning objects, isolating them from the outside environment, and providing more effective cooling. This type of extinguishing agent has advantages such as high extinguishing efficiency, good anti-reignition performance, and wide application scenarios. To improve this, this invention uses trace amounts of short-chain fluorosurfactants, which have the advantages of being non-toxic, biodegradable, and environmentally friendly after use. To further improve its surface activity, this invention uses trace amounts of short-chain fluorosurfactants and organosilicon surfactants as the core, compounded with various anionic surfactants. To ensure that the environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire treatment has rapid spreading performance when the foam liquid falls onto the transformer oil surface, thereby cooling the surface of combustible materials, isolating oxygen, and preventing the volatilization of combustible materials, this invention explores the specific components of the required compounded surfactants. Verification has shown that the use of anionic surfactants AOS and SDS, combined with trace amounts of short-chain fluorinated surfactants and organosilicon surfactants, can ensure that the prepared environmentally friendly aqueous film-forming foam fire extinguishing agent has the ability to spread rapidly when the actual foam liquid falls onto the surface of transformer oil, thereby cooling the surface of combustibles, isolating oxygen, and preventing the volatilization of combustibles.

[0015] It should be noted that the anionic surfactant AOS, or sodium α-olefin sulfonate, is a highly foaming, hydrolyzed, and stable anionic surfactant with excellent hard water resistance. It is low in toxicity, mild, low in irritation, and readily biodegradable. AOS exhibits excellent surface activity; within a certain concentration range, it can reduce the surface tension of water from 72 mN·m. -1 Reduced to 30-40 mN.m -1 AOS has good foaming power. The foaming power of AOS does not change significantly under both hard and soft water conditions. More importantly, numerous experimental results show that AOS is safe for humans and the environment.

[0016] In some embodiments, the anionic surfactant AOS can be a commercially available product or can be prepared by the following methods, and the present invention does not impose any special limitations on this.

[0017] A continuous process for producing powdered sodium α-alkenyl sulfonate; the production process and its preparation equipment should be characterized by simple equipment, energy saving and environmental protection, and high production efficiency, and the obtained powdered sodium α-alkenyl sulfonate should have a high content of active ingredients and low sulfonyl lactone residue. The process includes the following steps: 1) Alkenyl sulfonate esters after sulfonation and aging of α-olefins, caustic soda flakes, and recycled materials after neutralization are fed into a neutralizer at a certain flow rate for neutralization; 2) The neutralized materials are conveyed by a neutralization conveying pump, and a portion of the materials are recycled and reused after being heated by a heater and then fed into the Chemicalbook neutralizer; the other portion is conveyed from the bottom by a hydrolysis conveying pump after passing through a back pressure valve into a hydrolysis column with a stirrer, while a high-pressure steam is introduced from the bottom of the hydrolysis column; 3) The neutralized materials in the hydrolysis column undergo a hydrolysis reaction under the action of steam, and finally overflow from the discharge port on the upper side of the hydrolysis column under a certain pressure; at the same time, the excess steam participating in the hydrolysis is controlled to be released from the top of the hydrolyzer under a certain pressure; 4) The overflow material is dehydrated by flash evaporation, cooled, shaped and crushed to obtain the finished powdered sodium α-alkene sulfonate.

[0018] It should also be noted that the anionic surfactant SDS is sodium dodecyl sulfate, abbreviated as SDS. It is an anionic surfactant, also known as sodium coconut oil (or lauryl alcohol) sulfate, K12, foaming agent, etc. Its chemical formula is C12. 12 H 25 SO4Na is a white or pale yellow powder, readily soluble in water, and insensitive to alkalis and hard water. It possesses excellent detergency, emulsifying, and foaming properties. Its biodegradability is >90%, apparent density is 0.25 g / ml, melting point is 180–185℃ (decomposes), it is readily soluble in water, and has an HLB value of 40. It is a non-toxic anionic surfactant. It exhibits good compatibility with anionic and nonionic surfactants and demonstrates excellent emulsifying, foaming, penetrating, detergency, and dispersing properties.

[0019] In some embodiments, the anionic surfactant SDS can be a commercially available product or can be prepared by the following methods, and the present invention does not impose any special limitations on this.

[0020] Sodium dodecyl sulfate can be prepared by the following method:

[0021] In a fume hood, place 9.5 mL of glacial acetic acid into a dry reaction flask and cool it thoroughly in an ice bath. Add 3.5 mL (0.053 mol) of chlorosulfonic acid and mix well. Over 5 minutes, slowly add 8 g (0.043 mol) of dodecanoic acid, either in liquid or very fine powder form, to the cold acetic acid and chlorosulfonic acid mixture, stirring for 30 minutes until all the alcohol is dissolved and participates in the reaction. If the alcohol is not completely dissolved, remove the reaction flask from the ice bath and stir at room temperature for 10 minutes. Pour the reaction mixture into a beaker containing 30 g of crushed ice. Add 30 mL of n-butanol to the mixture and stir for 3 minutes. Slowly add 3 mL of saturated sodium carbonate aqueous solution while stirring; the solution should be alkaline to litmus paper. Once the reaction becomes alkaline, add 10 g of solid anhydrous sodium carbonate and allow to stand. Pour the upper n-butanol solution from the surface of the aqueous layer into the beaker. Add another 20 mL of n-butanol to the aqueous layer and stir thoroughly to separate the n-butanol layer. Combine the two n-butanol extracts and pour them into a separatory funnel to separate the aqueous layer. Pour the n-butanol solution into a beaker and evaporate the n-butanol to obtain a white residue, which is sodium dodecyl sulfate.

[0022] Alternatively, the sulfur trioxide method: The reaction apparatus is a vertical reactor. Nitrogen gas is introduced into the reactor through a gas nozzle at 32°C. The nitrogen flow rate is 85.9 L / min. Lauryl alcohol is introduced at 82.7 kPa at a flow rate of 58 g / min. Liquid sulfur trioxide is introduced into a flash evaporator at 124.1 kPa, with the flash temperature maintained at 100°C and the sulfur trioxide flow rate controlled at 0.9072 kg / h. The sulfation product is then rapidly cooled to 50°C and placed in an aging tank for 10–20 min. Finally, it is transferred to a neutralization reactor for neutralization with alkali. The neutralization temperature is controlled at 50°C, and the product is discharged when the pH reaches 7–8.5, yielding the liquid product. The solid product is obtained by spray drying.

[0023] Alternatively, add 62g of lauryl alcohol to a 250mL four-necked flask equipped with a hydrogen chloride absorption device, thermometer, electric stirrer, and dropping funnel. Maintain the temperature at 25°C. While stirring thoroughly, slowly add 24mL of chlorosulfonic acid dropwise over 30 minutes using a dropping funnel. The temperature should not exceed 30°C during the addition; be careful to avoid foaming and prevent overflow. After adding the chlorosulfonic acid, react at 30°C for 2 hours. Absorb the hydrogen chloride gas produced during the reaction with a 5% sodium hydroxide solution. After sulfation, slowly pour the sulfated product into a mixture of 100g of ice and water (ice:water = 2:1) while stirring thoroughly. Cool the mixture in an ice-water bath. Finally, wash the entire mixture out of the four-necked flask with a small amount of water. After dilution, neutralize to pH 7-8.5 by adding a 30% sodium hydroxide solution dropwise while stirring. Then extract with n-butanol and evaporate the n-butanol.

[0024] At 20℃, the surface tension of water is 72.75 mN / m. When substances with different properties are dissolved in water, the surface tension of the water changes. Surface tension decreases with increasing concentration, exhibiting three patterns: increase, gradual decrease, and rapid decrease. Substances exhibiting the third pattern are defined as surfactants. A substance that fully meets the criteria for a surfactant in this third pattern, and that can significantly reduce the surface tension of the solvent (generally water) and the liquid-liquid interfacial tension, is called a surfactant. All surfactants consist of polar hydrophilic groups and nonpolar lipophilic groups. Based on the structure of their hydrophilic groups, surfactants are classified into cationic, anionic, amphoteric, and nonionic types.

[0025] In order to provide a compound surfactant for an environmentally friendly aqueous film-forming foam fire extinguishing agent suitable for transformer oil fire treatment, the present invention further explores the types and proportions of the trace short-chain fluorinated surfactant and organosilicon surfactant.

[0026] Surfactants composed of siloxanes as hydrophobic groups and polyoxyethylene chains, carboxyl groups, ketone groups, amino groups, epoxy groups, and other polar groups as hydrophilic groups are called organosilicon surfactants. Due to the characteristics of the organosilicon molecular structure, it possesses many properties not found in other organic groups, such as low surface tension, high surface activity, excellent wetting, emulsifying, lubricating, physiological inertness, chemical stability, non-toxicity, odorlessness, chemical degradation, non-accumulation, and good air permeability. Therefore, its applications are extremely wide-ranging, including waterproofing, softening, smoothing, and finishing of fibers, fabrics (including non-woven fabrics), and leather; industrial applications in mining, oil extraction, chemical processing, plastics and rubber production, and metal processing; personal protective equipment and automotive detailing; and agricultural chemicals, etc. Based on the structure of the hydrophilic group, it is also classified into cationic, anionic, amphoteric, and nonionic types. Therefore, in some effective embodiments, the organosilicon nonionic surfactant is DOWSIL 5211.

[0027] Fluorocarbon surfactants are among the most active surfactants known to date, widely studied and applied due to their high surface activity, high chemical stability, high thermal stability, and dual hydrophobic and oleophobic properties. Among these fluorocarbon surfactants, perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are relatively inexpensive, making them commonly used as starting materials. However, research indicates that PFOA / PFOS are stable and extremely difficult to degrade. These types of fluorocarbon surfactants tend to accumulate in organisms and possess a certain degree of toxicity, posing a threat to the environment. Their use has been banned in many countries. Therefore, finding suitable low-toxicity and highly efficient PFOA / PFOS substitutes has become an important direction in the research of novel fluorocarbon surfactants. Given the high efficiency of fluorocarbon surfactants, efforts are being made to modify their structure, shortening the "effective length" of the fluorocarbon chain or inserting heteroatoms such as N and O into long fluorocarbon chains. This allows them to maintain the high surface activity of fluorocarbon surfactants while reducing or eliminating their environmental harm. Relevant literature reports have shown that when the fluorocarbon chain length is less than or equal to 4, its environmental harm can be basically ignored. Therefore, in some effective embodiments, the short fluorocarbon chain amphoteric surfactant is FS-50.

[0028] Furthermore, this invention provides a combination of the above-mentioned compound surfactants, wherein the compound surfactant is a combination of the organosilicon nonionic surfactant DOWSIL 5211 and the short-fluorocarbon chain amphoteric surfactant FS-50; in this series of embodiments, the anionic surfactants are the anionic surfactants AOS and SDS. Specifically, in one embodiment of the first aspect of this invention, the constituent raw materials of the compound surfactant include: the organosilicon nonionic surfactant DOWSIL 5211 and the short-fluorocarbon chain amphoteric surfactant FS-50, the anionic surfactant AOS, and the anionic surfactant SDS. Meanwhile, in one embodiment of the first aspect of this invention, the constituent raw materials of the fire extinguishing agent include: the organosilicon nonionic surfactant DOWSIL 5211 and the short-fluorocarbon chain amphoteric surfactant FS-50, the anionic surfactant AOS, the anionic surfactant SDS, a thickener, an antifreeze agent, a foam stabilizer, a preservative, and water;

[0029] Extensive and repeated experiments conducted according to this invention show that, in the above-mentioned compound surfactant and environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire treatment, the organic silicone nonionic surfactant DOWSIL 5211, the short fluorocarbon chain amphoteric surfactant FS-50, the anionic surfactant AOS, and the anionic surfactant SDS are mixed in a certain proportion, and thickener, antifreeze, foam stabilizer, and preservative are added. After continuous stirring and the addition of water, the resulting environmentally friendly aqueous film-forming foam extinguishing agent can ensure rapid spreading performance when the actual foam liquid falls onto the surface of transformer oil, thereby cooling the surface of combustibles, isolating oxygen, and preventing the volatilization of combustibles.

[0030] In some effective embodiments, the mass percentages of each component in the compound surfactant are as follows: 0.4wt%-1.2wt% of organosilicon nonionic surfactant, 5wt%-7.5wt% of short-chain fluorocarbon amphoteric surfactant, 16wt%-24wt% of anionic surfactant AOS, and 55wt%-80wt% of anionic surfactant SDS, with the sum of the percentages of each component being 100%. It should be noted that the combination of DOWSIL 5211, short-chain fluorocarbon amphoteric surfactant FS-50, anionic surfactant AOS, and anionic surfactant SDS can effectively ensure rapid spreading performance when the foam liquid falls onto the transformer oil surface, thereby cooling the surface of combustible materials, isolating oxygen, and preventing the volatilization of combustible materials. However, excessively low or high amounts of organosilicon nonionic surfactant DOWSIL 5211, short-chain fluorocarbon amphoteric surfactant FS-50, anionic surfactant AOS, and anionic surfactant SDS may have certain effects. For example, the amount of organosilicon nonionic surfactant DOWSIL 5211 may be too low or too high. If the concentration of 5211 is too low, it can improve the activity of surfactants, but when it is dropped onto the surface of transformer oil, it cannot spread spontaneously.

[0031] In some effective embodiments, the mass percentage of each component in the compound surfactant is as follows: 0.8wt%-1.2wt% of organosilicon nonionic surfactant, 6wt%-7wt% of short fluorocarbon chain amphoteric surfactant, 18wt%-20wt% of anionic surfactant AOS, and 71.8wt%-75.2wt% of anionic surfactant SDS, with the sum of the percentages of each component being 100%.

[0032] In some effective embodiments, the mass percentage of each component in the compound surfactant is as follows: 1.2 wt% organosilicon nonionic surfactant, 7 wt% short fluorocarbon chain amphoteric surfactant, 20 wt% anionic surfactant AOS, and 71.8 wt% anionic surfactant SDS.

[0033] In some more effective embodiments, the mass percentage of each component in the compound surfactant is as follows: 0.8 wt% organosilicon nonionic surfactant, 6 wt% short fluorocarbon chain amphoteric surfactant, 18 wt% anionic surfactant AOS, and 75.2 wt% anionic surfactant SDS.

[0034] In some embodiments, the thickener is polyethylene glycol.

[0035] In some embodiments, the antifreeze is a mixture of ethylene glycol and glycerin;

[0036] In some embodiments, the volume ratio of ethylene glycol to glycerol is 1:3 to 3:1.

[0037] In some embodiments, the foam stabilizer is fly ash;

[0038] Alternatively, the fly ash has a particle size of less than 500 nm and a contact angle with deionized water of 80° to 130°.

[0039] In some embodiments, the preservative is Kathon;

[0040] In some embodiments, the water is deionized water.

[0041] A second aspect of the present invention provides a method for preparing an environmentally friendly aqueous film-forming foam fire extinguishing agent suitable for transformer oil fire suppression, comprising:

[0042] An organosilicon nonionic surfactant, a short fluorocarbon chain amphoteric surfactant, an anionic surfactant AOS, and an anionic surfactant SDS are added sequentially to water and mixed evenly to obtain a surfactant solution.

[0043] A thickener is added to the surfactant solution and mixed thoroughly to obtain a first mixture.

[0044] Add a foam stabilizer to the first mixture and mix well to obtain a second mixture;

[0045] Add antifreeze and preservative to the second mixture and mix well to obtain the final product.

[0046] In the study of the preparation method, the mixing order and temperature of the surfactant, co-surfactant and oil phase have a significant impact on the stability of the microemulsion formulation. The preparation method provided by the present invention first mixes the surfactant at a higher temperature, and then mixes in the oil phase and drug in sequence to facilitate the full binding of the carrier excipients and the dissolution of the drug, which helps the uniformity and stability of the prepared microemulsion. Then, an aqueous phase is added to obtain an O / W type microemulsion formulation.

[0047] In some implementations, the initial temperature of the water is 20°C to 25°C;

[0048] In some embodiments, the mixing time of the surfactant is 10 to 12 minutes;

[0049] In some embodiments, the mixing conditions for adding the thickener are stirring at a speed of 600 to 1200 rpm until the solution is clear and free of precipitate;

[0050] In some embodiments, the mixing conditions for adding the foam stabilizer are stirring at a speed of 600-1200 rpm for 1-2 hours;

[0051] In some embodiments, the mixing time after adding the antifreeze and preservative is 20 to 24 minutes.

[0052] More specifically, the preparation steps are as follows:

[0053] (1) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0054] (2) Add DOWSIL 5211, FS-50, AOS and SDS to the mixer in sequence and stir for 10 minutes.

[0055] (3) Slowly add the thickener to the stirrer and stir continuously at a speed of 600-1200 rpm until the solution is clear and free of precipitate;

[0056] (4) Slowly add the foam stabilizer to the mixer and stir continuously at a speed of 600-1200 rpm for 1-2 hours;

[0057] (5) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0058] Beneficial effects of the present invention

[0059] (1) The foam fire extinguishing agent composition described in this invention is designed for the physical and chemical properties of transformer oil, which can ensure that the foam liquid can spread rapidly when it falls onto the surface of transformer oil, thereby cooling the surface of combustibles, isolating oxygen, and preventing combustibles from volatilizing.

[0060] (2) The raw materials involved in this invention are non-toxic, biodegradable, and do not pollute the environment after use.

[0061] (3) This invention uses fly ash as a foam stabilizer raw material, turning waste particulate matter from thermal power plants into a valuable resource. This particulate foam stabilizer can greatly improve the stabilization time of fire extinguishing foam, making the foam more effective at isolating oxygen and resisting reignition than traditional two-phase aqueous film-forming foam.

[0062] (4) This invention contains antifreeze components and can be used normally under conditions where the temperature is above -20℃.

[0063] (5) The preparation method of the present invention is simple, practical and easy to promote. Detailed Implementation

[0064] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0065] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0066] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0067] Example 1

[0068] (1) Prepare the surfactant components according to the following proportions:

[0069]

[0070] (2) Prepare other raw materials according to the following proportions:

[0071]

[0072] (4) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0073] (5) Add DOWSIL 5211, FS-50, AOS and SDS to the mixer in sequence and stir for 10 minutes.

[0074] (6) Slowly add the thickener to the stirrer and stir continuously at 600 rpm until the solution is clear and free of precipitate;

[0075] (7) Slowly add the foam stabilizer to the mixer and stir continuously at 600 rpm for 2 hours;

[0076] (8) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0077] Example 2

[0078] (1) Prepare the surfactant components according to the following proportions:

[0079]

[0080] (2) Prepare other raw materials according to the following proportions:

[0081]

[0082] (4) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0083] (5) Add DOWSIL 5211, FS-50, AOS and SDS to the mixer in sequence and stir for 10 minutes.

[0084] (6) Slowly add the thickener to the stirrer and stir continuously at 1200 rpm until the solution is clear and free of precipitate;

[0085] (7) Slowly add the foam stabilizer to the mixer and stir continuously at 1200 rpm for 1 hour;

[0086] (8) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0087] Comparative Example 1:

[0088] The difference from Example 1 is that the silicone surfactant DOWSIL 5211 was not added.

[0089] (1) Prepare the surfactant components according to the following proportions:

[0090] FS-50 7wt%

[0091] AOS 20wt%

[0092] SDS 73wt%

[0093] (2) Prepare other raw materials according to the following proportions:

[0094]

[0095] (4) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0096] (5) Slowly add FS-50, AOS and SDS to the mixer in sequence and stir for 10 minutes.

[0097] (6) Slowly add the thickener to the stirrer and stir continuously at 600 rpm until the solution is clear and free of precipitate;

[0098] (7) Slowly add the foam stabilizer to the mixer and stir continuously at 600 rpm for 2 hours;

[0099] (8) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0100] Comparative Example 2:

[0101] The difference from Example 1 is that the anionic surfactant AOS was not added.

[0102] (1) Prepare the surfactant components according to the following proportions:

[0103] DOWSIL 5211 1.2wt%

[0104] FS-50 7wt%

[0105] SDS 91.8wt%

[0106] (2) Prepare other raw materials according to the following proportions:

[0107]

[0108] (4) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0109] (5) Add DOWSIL 5211, FS-50 and SDS to the mixer in sequence and stir for 10 minutes.

[0110] (6) Slowly add the thickener to the stirrer and stir continuously at 600 rpm until the solution is clear and free of precipitate;

[0111] (7) Slowly add the foam stabilizer to the mixer and stir continuously at 600 rpm for 2 hours;

[0112] (8) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0113] Comparative Example 3:

[0114] The difference from Example 1 is that the anionic surfactant SDS was not added.

[0115] (1) Prepare the surfactant components according to the following proportions:

[0116] DOWSIL 5211 1.2wt%

[0117] FS-50 7wt%

[0118] AOS 91.8wt%

[0119] (2) Prepare other raw materials according to the following proportions:

[0120]

[0121]

[0122] (4) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0123] (5) Add DOWSIL 5211, FS-50 and AOS to the mixer in sequence and stir for 10 minutes.

[0124] (6) Slowly add the thickener to the stirrer and stir continuously at 600 rpm until the solution is clear and free of precipitate;

[0125] (7) Slowly add the foam stabilizer to the mixer and stir continuously at 600 rpm for 2 hours;

[0126] (8) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0127] Comparative Example 4:

[0128] The difference from Example 1 is that no foam stabilizer - fly ash - was added.

[0129] (1) Prepare the surfactant components according to the following proportions:

[0130]

[0131] (2) Prepare other raw materials according to the following proportions:

[0132]

[0133] (4) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0134] (5) Add DOWSIL 5211, FS-50, AOS and SDS to the mixer in sequence and stir for 10 minutes.

[0135] (6) Slowly add the thickener to the stirrer and stir continuously at 600 rpm until the solution is clear and free of precipitate;

[0136] (7) Slowly add the foam stabilizer to the mixer and stir continuously at 600 rpm for 2 hours;

[0137] (8) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0138] Comparative Example 5:

[0139] The difference from Example 1 is that the antifreeze agents glycerol and ethylene glycol were not added.

[0140] (1) Prepare the surfactant components according to the following proportions:

[0141]

[0142] (2) Prepare other raw materials according to the following proportions:

[0143]

[0144]

[0145] (4) Add deionized water to the stirrer and control the temperature at 20℃~25℃;

[0146] (5) Add DOWSIL 5211, FS-50, AOS and SDS to the mixer in sequence and stir for 10 minutes.

[0147] (6) Slowly add the thickener to the stirrer and stir continuously at 600 rpm until the solution is clear and free of precipitate;

[0148] (7) Slowly add the foam stabilizer to the mixer and stir continuously at 600 rpm for 2 hours;

[0149] (8) Add the antifreeze and preservative to the mixer and stir continuously for 20 minutes.

[0150] The performance of the extinguishing agents in the above embodiments and comparative examples was tested:

[0151] 1) Test method for spreading radius: Place 2 mL of sample foam liquid with a mass concentration of 3% close to the surface of transformer oil and drip it onto the surface of transformer oil within 1 second. Record the change of the spreading diameter of the foam liquid on the oil surface over time using a camera.

[0152] 2) Test method for foam volume and foam volume half-life: Prepare a foam liquid sample with a mass concentration of 3%, and use a Ross-Miles foam analyzer to test the foam volume and foam volume half-life according to the standard GB / T13173-2008.

[0153] 3) Freezing point test method: The freezing point test shall be conducted in accordance with the standard GB27897-2011.

[0154] 4) Test method for fire extinguishing time and fire resistance time: The test shall be conducted in accordance with the standard GB15308-2006.

[0155] The test results are shown in Table 1 below:

[0156] Table 1. Key performance test results of foaming liquids from different embodiments.

[0157]

[0158] As shown in Table 1 above, the proportions of fluorinated surfactant, silicone surfactant, foam stabilizer, and antifreeze in Example 2 are slightly lower than those in Example 1. Therefore, the spreading radius and foam volume half-life of Example 2 are slightly smaller than those of Example 1, and the freezing point is slightly higher. Since the proportion of hydrocarbon surfactant in Example 2 is higher than that in Example 1, the foaming power of Example 2 is slightly higher than that of Example 1. The fire extinguishing and anti-burning performance of Example 2 is slightly weaker than that of Example 1.

[0159] Compared to Example 1, Comparative Example 1 did not contain the silicone surfactant DOWSIL 5211, resulting in a spreading radius of less than half that of Example 1 and a slightly lower foam volume half-life. Other parameters were not significantly different. The fire extinguishing performance of Comparative Example 1 was significantly weaker than that of Example 1, while the difference in fire resistance was not significant.

[0160] Compared to Example 1, Comparative Example 2 did not contain the anionic surfactant AOS, resulting in a significantly lower spreading radius and foam volume compared to Example 1. The foam volume half-life was slightly lower in Comparative Example 2, while the freezing point was not significantly different from Example 1. The fire extinguishing performance of Comparative Example 2 was significantly weaker than that of Example 1, while the difference in fire resistance was not significant.

[0161] Compared with Example 1, Comparative Example 3 did not contain the anionic surfactant SDS, resulting in a significantly lower spreading radius and foam volume compared to Example 1. The foam volume half-life and freezing point were not significantly different from Example 1. The fire extinguishing performance of Comparative Example 3 was significantly weaker than that of Example 1, while the difference in fire resistance was not significant.

[0162] Compared to Example 1, Comparative Example 4 did not include a foam stabilizer—fly ash. This resulted in Comparative Example 4 having a foam volume half-life that was only 1 / 8 that of Example 1. Other parameters were not significantly different from Example 1, indicating that the foam stabilizing particles are crucial for significantly improving foam stability and fire resistance. The fire resistance of Comparative Example 4 was significantly weaker than that of Example 1, while the fire extinguishing performance was not significantly different.

[0163] Compared with Example 1, Comparative Example 5 did not include antifreeze agents glycerol and ethylene glycol, resulting in a freezing point of Comparative Example 4 that was much higher than that of Example 1, making it unsuitable for the low winter temperatures in northern my country.

[0164] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An environmentally friendly aqueous film-forming foam extinguishing agent suitable for handling transformer oil fires, characterized in that, The extinguishing agent is composed of the following raw materials by weight percentage: compound surfactant 8wt%-22wt%, thickener 5wt%-15wt%, antifreeze 10wt%-20wt%, foam stabilizer 5wt%-8wt%, preservative 0.5wt%-1wt%, and the balance being water; The compound surfactant is composed of an organosilicon nonionic surfactant, a short fluorocarbon chain amphoteric surfactant, an anionic surfactant AOS, and an anionic surfactant SDS. The organosilicon nonionic surfactant is DOWSIL 5211; The short-chain amphoteric surfactant is FS-50; The foam stabilizer is fly ash; The fly ash has a particle size of less than 500 nm and a contact angle with deionized water of 80°~130°; The mass percentage of each component in the compound surfactant is as follows: 0.4wt%-1.2wt% of organosilicon nonionic surfactant, 5wt%-7.5wt% of short fluorocarbon chain amphoteric surfactant, 16wt%-24wt% of anionic surfactant AOS, and 55wt%-80wt% of anionic surfactant SDS. The sum of the percentages of each component is 100%.

2. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The mass percentage of each component in the compound surfactant is as follows: 0.8wt%-1.2wt% of organosilicon nonionic surfactant, 6wt%-7wt% of short fluorocarbon chain amphoteric surfactant, 18wt%-20wt% of anionic surfactant AOS, and 71.8wt%-75.2wt% of anionic surfactant SDS. The sum of the percentages of each component is 100%.

3. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The mass percentages of each component in the compound surfactant are as follows: 1.2 wt% organosilicon nonionic surfactant, 7 wt% short fluorocarbon chain amphoteric surfactant, 20 wt% anionic surfactant AOS, and 71.8 wt% anionic surfactant SDS.

4. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The mass percentages of each component in the compound surfactant are as follows: 0.8 wt% organosilicon nonionic surfactant, 6 wt% short fluorocarbon chain amphoteric surfactant, 18 wt% anionic surfactant AOS, and 75.2 wt% anionic surfactant SDS.

5. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The extinguishing agent is composed of the following raw materials by weight percentage: 20wt%-22wt% compound surfactant, 8wt%-15wt% thickener, 14wt%-15wt% antifreeze agent, 6wt%-8wt% foam stabilizer, 0.5wt% preservative, and the balance being water.

6. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The extinguishing agent is composed of the following raw materials by weight percentage: 20wt% compound surfactant, 8wt% thickener, 15wt% antifreeze agent, 6wt% foam stabilizer, 0.5wt% preservative, and the balance being water.

7. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The extinguishing agent is composed of the following raw materials by weight percentage: 22wt% compound surfactant, 15wt% thickener, 8wt% antifreeze, 8wt% foam stabilizer, 0.5wt% preservative, and the balance being water.

8. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The thickener is polyethylene glycol.

9. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The antifreeze agent is a mixture of ethylene glycol and glycerin; Alternatively, the volume ratio of ethylene glycol to glycerol is 1:3 to 3:

1.

10. The environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression as described in claim 1, characterized in that, The preservative mentioned is Kathon; Alternatively, the water may be deionized water.

11. A method for preparing an environmentally friendly aqueous film-forming foam extinguishing agent suitable for transformer oil fire suppression, characterized in that, include: An organosilicon nonionic surfactant, a short fluorocarbon chain amphoteric surfactant, an anionic surfactant AOS, and an anionic surfactant SDS are added sequentially to water and mixed evenly to obtain a surfactant solution. A thickener is added to the surfactant solution and mixed thoroughly to obtain a first mixture. Add a foam stabilizer to the first mixture and mix well to obtain a second mixture; Add antifreeze and preservative to the second mixture and mix well to obtain the final product; The mass percentages of each component are as follows: 0.4wt%-1.2wt% of organosilicon nonionic surfactant, 5wt%-7.5wt% of short fluorocarbon chain amphoteric surfactant, 16wt%-24wt% of anionic surfactant AOS, and 55wt%-80wt% of anionic surfactant SDS. The sum of the percentages of each component is 100%. The organosilicon nonionic surfactant is DOWSIL 5211; The short-chain amphoteric surfactant is FS-50; The foam stabilizer is fly ash; The fly ash has a particle size of less than 500 nm and a contact angle with deionized water of 80°~130°.

12. The preparation method of the environmentally friendly aqueous film-forming foam fire extinguishing agent suitable for transformer oil fire fighting as described in claim 11, characterized in that, The initial temperature of the water is 20℃~25℃; Alternatively, the mixing time for the surfactant is 10-12 minutes; Alternatively, the mixing conditions for adding thickener are stirring at a speed of 600~1200 rpm until the solution is clear and free of precipitate; Alternatively, the mixing conditions for adding the foam stabilizer are stirring at a speed of 600~1200 rpm for 1-2 hours; Alternatively, the mixing time after adding antifreeze and preservatives is 20-24 minutes.

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