Dry powder extinguishing agent and preparation method thereof

Abstract

The invention discloses a dry powder extinguishing agent and a preparation method thereof, and belongs to the technical field of extinguishing agents. The dry powder extinguishing agent comprises chlorine salt, expansible graphite, high-melting-point inorganic glue, hydrogen-containing silicone oil, white carbon black, mica and the like. The dry powder extinguishing agent is suitable for various fire behaviors, has a good fire extinguishing effect on ABCDF type fire behaviors, is non-toxic, free of side effects, free of stimulation and damage to personnel, green, environmentally friendly and free of environmental pollution, meanwhile, the dry powder extinguishing agent is short in fire extinguishing time, and the fire extinguishing effect is good. Compared with a dry powder extinguishing agent on the market at present, the extinguishing time can be shortened by half under the same condition; and after fire extinguishing, no after-combustion phenomenon occurs.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire extinguishing agents, and in particular relates to a dry powder fire extinguishing agent and a preparation method thereof. Background Art

[0002] Fires are generally categorized into five types: A, B, C, and D. Class A refers to fires involving solids; Class B refers to fires involving liquids or soluble solids; Class C refers to gas fires; Class D refers to metal fires; and Class E refers to electrical fires, where objects are electrically charged and burning. Therefore, different types of fire extinguishing agents are required depending on the nature and characteristics of each fire.

[0003] Dry powder fire extinguishing agent is a commonly used fire extinguishing agent. It is dry, easy to flow, has good moisture resistance and anti-caking properties, and is widely used in oil fields, oil depots, refineries, chemical plants, chemical warehouses, ships, airports, and industrial and mining enterprises. The dry powder fire extinguishing agents currently used are mainly divided into the following three categories:

[0004] The first type uses sodium chloride, potassium chloride, or barium chloride as its primary raw materials, and may also include organic compounds. It is primarily used for Class D fires. Dry sodium chloride, potassium chloride, or barium chloride has poor thermal conductivity and can absorb heat from the burning metal surface and adhere to it. Simultaneously, the organic compounds in the dry powder decompose under the high temperature of the metal surface and, together with the chlorides, form a coating on the burning metal surface, isolating it from the air and extinguishing the fire.

[0005] The second category is multi-purpose dry powder fire extinguishing agents, also known as ABC dry powder fire extinguishing agents. These are based on ammonium phosphate salts and may contain ammonium sulfide or ammonium phosphate. These dry powder fire extinguishing agents are suitable for ABCE fires. During combustion, ammonium phosphate salts absorb heat and decompose into ammonia and phosphoric acid. The free ammonia reacts with the hydroxyl radicals produced during the flame combustion reaction, reducing and terminating the free radical production, slowing the combustion reaction rate and extinguishing the fire. Furthermore, when ammonium phosphate salts decompose at high temperatures, they can form a glassy film on the surface of solid materials, coating the burning material. Upon cooling, a brittle coating forms, isolating the burning surface from the air. When the coating reaches a certain thickness, it can prevent re-ignition.

[0006] The third type is ordinary dry powder fire extinguishing agent, also known as BC dry powder fire extinguishing agent, which uses sodium bicarbonate or potassium bicarbonate as main raw materials. This type of dry powder fire extinguishing agent can only be used for BCE type fires; it mainly uses the bicarbonate in the dry powder to decompose under high temperature, releasing a large amount of carbon dioxide and water, which plays a certain role in cooling and diluting combustible gases.

[0007] Existing dry powder fire extinguishing agents generally have the following disadvantages: (1) poor versatility and a narrow range of applicable fire types, or only applicable to Class ABC or Class D; (2) unsatisfactory fire extinguishing effect and a large amount of fire extinguishing agent used; (2) a high probability of re-ignition after initial extinguishing. Summary of the Invention

[0008] In view of the above-mentioned prior art, the present invention provides a dry powder fire extinguishing agent and a preparation method thereof to solve the technical problems of the prior art dry powder fire extinguishing agents, such as poor versatility, unsatisfactory fire extinguishing effect and high probability of re-ignition.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is to provide a dry powder fire extinguishing agent, including the following components: chloride salt, expandable graphite, high melting point inorganic glue, hydrogen-containing silicone oil, white carbon black and mica.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the mass percentage of each component in the dry powder fire extinguishing agent is:

[0012] Chloride salt 15~70%, expandable graphite 5~55%, high melting point inorganic glue 1~10%, hydrogenated silicone oil 1~5%, white carbon black 2~8%, mica 3~10%.

[0013] Furthermore, the mass percentage of each component in the dry powder fire extinguishing agent is:

[0014] Chloride salt 50%, expandable graphite 20%, high melting point inorganic glue 10%, hydrogen-containing silicone oil 5%, white carbon black 7%, mica 8%. Furthermore, the chloride salt is sodium chloride and / or potassium chloride.

[0015] Furthermore, the high melting point inorganic glue is a sodium silicate-based inorganic glue.

[0016] The fire extinguishing mechanism of the dry powder fire extinguishing agent in the present invention is as follows:

[0017] 1. Chloride Fire Extinguishing Mechanism: Dry powder fire extinguishing agents exist in powder form. When sprayed toward a fire source, the chloride powder rapidly melts, forming a liquid film that covers the metal surface. This film isolates the metal from air (oxygen), preventing the oxidation reaction from continuing.

[0018] 2. Fire extinguishing mechanism of high melting point inorganic adhesive: It melts at high temperature and eventually sinters to form a hard, low thermal conductivity silicate covering layer, which physically isolates oxygen.

[0019] 3. The fire extinguishing mechanism of expandable graphite: rapid physical expansion upon heating, forming a thick, porous carbon layer that tightly covers the surface of the burning metal, cutting off oxygen supply and blocking heat transfer, thus achieving the effect of suffocation and preventing rekindling. Its expansion process is also accompanied by significant endothermic effect.

[0020] When the flame is extinguished, the chlorides, expandable graphite, high-melting-point inorganic glue, etc. can quickly form a dense shell to prevent rekindling. That is, the dry powder extinguishing agent in the present application can uniformly cover the surface of the burning material and form a dense barrier, thereby cutting off the oxygen supply and causing the combustion reaction to terminate due to lack of oxygen. In addition, the extinguishing agent of the present application also has the property of adhering to the wall: the dry powder extinguishing agent in the present application contains components such as high-melting-point inorganic glue, which can stably adhere to the burning surface for vertical or inclined surface fires (such as molten metal flowing fire), thereby preventing the spread of fire.

[0021] The present application also discloses a preparation method of the above-mentioned dry powder extinguishing agent, comprising the following steps:

[0022] S1: mixing chlorides, expandable graphite, white carbon black and mica, and drying the mixture under stirring, adding half of the amount of hydrogen-containing silicone oil during the drying process;

[0023] S2: crushing the mixture dried in S1 into a powder with a particle size distribution of D 10 ≤3.5 μm, D 50 ≤11.8 μm, and D 90 ≤51 μm;

[0024] S3: secondary drying of the powder obtained in S2 under stirring, adding high-melting-point inorganic glue and the remaining hydrogen-containing silicone oil during the drying process;

[0025] S4: screening the material after secondary drying, and obtaining the product.

[0026] Further, the drying temperature in S1 is 60-120℃, and the drying time is 1-5h.

[0027] Further, the drying temperature in S3 is 50-90℃, and the drying time is 1-4h.

[0028] Further, the stirring speed in S1 and S3 is 60-120rpm.

[0029] Further, the screening mesh size in S4 is 30-160 mesh.

[0030] The present application has the following beneficial effects:

[0031] 1. The dry powder extinguishing agent in the present application is suitable for various fire conditions, and has good extinguishing effect on ABCDF type fires.

[0032] 2. The dry powder fire extinguishing agent of the present invention is non-toxic, has no side effects, does not irritate or harm personnel, is green and environmentally friendly, and does not pollute the environment.

[0033] 3. The dry powder fire extinguishing agent of the present invention has a short fire extinguishing time, which can be shortened by half compared with the dry powder fire extinguishing agent currently on the market under the same conditions; and there is no re-ignition phenomenon after the fire is extinguished. DETAILED DESCRIPTION

[0034] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available products. Specific embodiments of the present invention will be described in detail below with reference to the examples.

[0035] Example 1:

[0036] A dry powder fire extinguishing agent comprising the following components in percentage by mass:

[0037] Sodium chloride 50%, expandable graphite 20%, sodium silicate-based inorganic glue 10%, hydrogenated silicone oil 5%, white carbon black 7%, mica 8%.

[0038] The dry powder fire extinguishing agent in this embodiment is prepared by the following steps:

[0039] S1: Sodium chloride, expandable graphite, white carbon black, and mica were mixed and dried at 80°C and 90 rpm for 4 hours. During the stirring process (about 2 hours), half of the hydrogenated silicone oil was added.

[0040] S2: Use air flow milling to grind the mixture dried in S1 into particles with a particle size distribution of D 10 ≤3.5μm, D 50 ≤11.8μm, D 90 Powder ≤51μm;

[0041] S3: The powder obtained in S2 was subjected to secondary stirring and drying at 60°C and a stirring speed of 90 rpm for 2 hours. During the secondary stirring and drying process (after stirring for about 1 hour), sodium silicate-based inorganic glue and the remaining hydrogenated silicone oil were added.

[0042] S4: Screen the material after secondary drying, with the screening mesh size ≥30 mesh and ≤160 mesh, collect the screened material, bag and seal it.

[0043] Example 2:

[0044] A dry powder fire extinguishing agent comprising the following components in percentage by mass:

[0045] Sodium chloride 20%, expandable graphite 55%, sodium silicate-based inorganic glue 2%, hydrogenated silicone oil 5%, white carbon black 8%, mica 10%.

[0046] The dry powder fire extinguishing agent in this embodiment is prepared by the following steps:

[0047] S1: Sodium chloride, expandable graphite, white carbon black, and mica were mixed and stirred and dried at 60°C and 120 rpm for 5 hours. During the stirring process (about 2 hours), half of the hydrogenated silicone oil was added.

[0048] S2: Use air flow milling to grind the mixture dried in S1 into particles with a particle size distribution of D 10 ≤3.5μm, D 50 ≤11.8μm, D 90 Powder ≤51μm;

[0049] S3: The powder obtained in S2 was subjected to secondary stirring and drying at 50°C and a stirring speed of 120 rpm for 4 hours; during the secondary stirring and drying process (after stirring for about 2 hours), sodium silicate-based inorganic glue and the remaining hydrogenated silicone oil were added;

[0050] S4: Screen the material after secondary drying, with the screening mesh size ≥30 mesh and ≤160 mesh, collect the screened material, bag and seal it.

[0051] Example 3:

[0052] A dry powder fire extinguishing agent comprising the following components in percentage by mass:

[0053] Sodium chloride 70%, expandable graphite 10%, sodium silicate-based inorganic glue 10%, hydrogenated silicone oil 3%, white carbon black 3%, mica 4%.

[0054] The dry powder fire extinguishing agent in this embodiment is prepared by the following steps:

[0055] S1: Sodium chloride, expandable graphite, white carbon black, and mica were mixed and stirred and dried at 120°C at a stirring speed of 60 rpm for 1 hour. During the stirring process (about 0.5 hour), half of the hydrogenated silicone oil was added.

[0056] S2: Use air flow milling to grind the mixture dried in S1 into particles with a particle size distribution of D 10 ≤3.5μm, D 50 ≤11.8μm, D 90 Powder ≤51μm;

[0057] S3: The powder obtained in S2 is subjected to secondary stirring drying at 90°C with a stirring speed of 60 rpm, and the time for secondary stirring drying is 1 h; sodium silicate-based inorganic glue and the remaining hydrogen-containing silicone oil are added during the secondary stirring drying (around 0.5 h after stirring);

[0058] S4: The material after secondary drying is subjected to screening, the screening mesh size is ≥ 30 mesh and ≤ 160 mesh, the screened material is collected, and is sealed in a bag to obtain the dry powder extinguishing agent.

[0059] Experimental example:

[0060] The dry powder extinguishing agents prepared in Examples 1-3 have similar performances, and the dry powder extinguishing agent in Example 1 is taken as an example to illustrate the extinguishing performance of the dry powder extinguishing agent.

[0061] The dry powder extinguishing agent in Example 1, the conventional D-class dry powder extinguishing agent and the commercially available ordinary dry powder extinguishing agent are used for extinguishing experiments, and the specific conditions are as follows:

[0062] Test method:

[0063] 1. Basis of test method

[0064] a. According to the standards of XF979-2012, 6.10.1 and 6.10.2, D-class fire extinguishing test is carried out;

[0065] b. According to the standards of GB 4066-2017, appendix C and D, ABC-class fire extinguishing test is carried out.

[0066] 2. Test method

[0067] 2.1. 2.5 Kg of magnesium chip fuel is laid in the center of a steel combustion tray (GB4351-2023 appendix F: 600*600mm).

[0068] 2.2. 20 liters of gasoline is poured into the steel combustion box.

[0069] 2.3. 2 Kg of neodymium iron boron metal powder is placed into the steel combustion box.

[0070] 2.4. Propane is used to ignite the magnesium chip fuel, and when the combustion progresses to the entire fuel surface, extinguishing is started, and the valve of the extinguisher is controlled to make the dry powder extinguishing agent fall into the steel tray as much as possible. After the spraying is completed, the steel tray is kept stationary for 60 min.

[0071] 2.5. An ignition rod is used to ignite the gasoline and neodymium iron boron metal powder, and when the complete combustion reaches the maximum fire, extinguishing is started, and the valve of the extinguisher is controlled to make the dry powder extinguishing agent fall into the steel box as much as possible. After the spraying is completed, the steel tray is kept stationary for 60 min.

[0072] Result judgment: In each test, the flames were completely extinguished before the end of the spraying, and the fire was successfully extinguished if it did not rekindle within 60 minutes after the end of the spraying.

[0073] 3. Experimental results

[0074] The fire extinguishing effects of the three dry powder fire extinguishing agents are shown in the following table:

[0075]

[0076] Although the specific embodiments of the present invention have been described in detail in conjunction with the embodiments, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A dry powder fire extinguishing agent, characterized in that: The invention comprises the following components: chloride salt, expandable graphite, high melting point inorganic glue, hydrogen-containing silicone oil, white carbon black and mica.

2. The dry powder fire extinguishing agent according to claim 1, characterized in that: The mass percentage of each component in dry powder fire extinguishing agent is: Chloride salt 15~70%, expandable graphite 5~55%, high melting point inorganic glue 1~10%, hydrogenated silicone oil 1~5%, white carbon black 2~8%, mica 3~10%.

3. The dry powder fire extinguishing agent according to claim 2, characterized in that: The mass percentage of each component in dry powder fire extinguishing agent is: Chloride salt 50%, expandable graphite 20%, high melting point inorganic glue 10%, hydrogenated silicone oil 5%, white carbon black 7%, mica 8%.

4. The dry powder fire extinguishing agent according to any one of claims 1 to 3, characterized in that: The chloride salt is sodium chloride and / or potassium chloride.

5. The dry powder fire extinguishing agent according to any one of claims 1 to 3, characterized in that: The high melting point inorganic glue is sodium silicate-based inorganic glue.

6. The method for preparing the dry powder fire extinguishing agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: mixing chloride salt, expandable graphite, white carbon black and mica, and drying the mixture under stirring conditions, adding half of the amount of hydrogenated silicone oil during the drying process; S2: The mixture dried in S1 is crushed into particles with a particle size distribution of D 10 ≤3.5μm, D 50 ≤11.8μm, D 90 Powder ≤51μm; S3: The powder obtained in S2 is subjected to secondary drying under stirring conditions, and a high melting point inorganic glue and the remaining hydrogenated silicone oil are added during the drying process; S4: Screen the secondary dried material to obtain.

7. The preparation method according to claim 6, characterized in that: In S1, the drying temperature is 60~120℃ and the drying time is 1~5h.

8. The preparation method according to claim 6, characterized in that: In S3, the drying temperature is 50~90℃ and the drying time is 1~4h.

9. The preparation method according to claim 6, characterized in that: The stirring speed in S1 and S3 is 60~120rpm.

10. The preparation method according to claim 6, characterized in that: The screening mesh size in S4 is 30~160 mesh.

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