Layered layout structure of light flame-retardant material for oil pit of electrical equipment and design method

Abstract

The invention discloses an electrical equipment oil pit light flame-retardant material layered layout structure and a design method, and belongs to the technical field of flame-retardant layers.The electrical equipment oil pit light flame-retardant material layered layout structure comprises an oil pit and a layered blocking system, and the layered blocking system is arranged in the oil pit; the layered barrier system sequentially comprises an elastic supporting buffer layer, an intelligent temperature control phase change layer, a gradient density flame-retardant layer and a nano coating protective layer from bottom to top. According to the layered layout structure of the light flame-retardant material for the oil pit of the electrical equipment and the design method, by optimizing the layered layout structure of the flame-retardant material and the design method, the overall fire resistance and safety of the oil pit are effectively improved, and meanwhile, the engineering construction and operation and maintenance cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant layer structures, in particular to a layered layout structure and a design method of a lightweight flame retardant material for an oil pit of electrical equipment. Background Art

[0002] Electrical equipment oil pits are primarily used to collect oil leaks from oil-immersed equipment such as transformers during accidents, preventing the spread of leaked oil and causing fires. Their fire safety is crucial. Currently, the main fire prevention measures for oil pits include installing firewalls, using sprinkler fire extinguishing systems, and laying flame-retardant layers within the pits. Traditional fire-retardant materials for oil pits use refractory materials such as pebbles. While these materials offer good high-temperature resistance, they are heavy, complex to construct, and have high maintenance costs. With the upgrade of power grid construction and the increasing safety requirements for power equipment, the shortcomings of existing flame-retardant measures in terms of adaptability, cost-effectiveness, and ease of construction are becoming increasingly apparent, necessitating the exploration of better fire-resistant materials and layout solutions. Summary of the Invention

[0003] The purpose of the present invention is to provide a layered layout structure and design method of lightweight flame-retardant materials for oil pits of electrical equipment. By optimizing the layered layout structure and design method of flame-retardant materials, the overall fire resistance and safety of the oil pit are effectively improved, while reducing the construction and operation and maintenance costs.

[0004] To achieve the above-mentioned objectives, the present invention provides a layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment, comprising an oil pit and a layered barrier system. The layered barrier system is arranged in the oil pit. The layered barrier system comprises, from bottom to top, an elastic support buffer layer, an intelligent temperature control phase change layer, a gradient density flame-retardant layer, and a nano-coating protective layer.

[0005] Preferably, the gradient density flame retardant layer is made of lightweight hollow balls composited with hollow glass microspheres and flame retardant resin. The gradient density flame retardant layer includes an upper layer of lightweight flame retardant material and a lower layer of lightweight flame retardant material. The upper layer of lightweight flame retardant material and the lower layer of lightweight flame retardant material are made of the same material but have different outer diameters.

[0006] Preferably, the elastic support buffer layer is placed at the bottom of the oil pit and is made of a low-density elastic foam metal material with a density of 15-30 kg / m 3 .

[0007] Preferably, the intelligent temperature-controlled phase change layer is composed of a composite of phase change material and lightweight porous ceramics, and the phase change temperature of the phase change material is 200-300°C.

[0008] Preferably, the surface of the nano-coating protective layer is coated with a nano-scale super-hydrophobic flame-retardant coating.

[0009] Preferably, oil drain ports are symmetrically provided at the bottom of the oil pit, and filters are provided at the oil drain ports.

[0010] The present invention also provides a method for designing a layered layout structure of a lightweight flame-retardant material for an oil pit of electrical equipment, comprising the following steps:

[0011] S1. Use computational fluid dynamics software to build a three-dimensional numerical model M of the oil pit fire scene;

[0012] S2. Set different oil leakage amounts and fire temperature ambient temperatures to simulate working conditions and obtain temperature distribution data in the oil pit;

[0013] S3. Using the temperature distribution data obtained by simulation, a neural network model N is trained to establish a temperature prediction model P;

[0014] S4. Based on P, the material parameters of the gradient density flame retardant layer are optimized to achieve precise control of the temperature field in the oil pit and achieve a flame retardant effect.

[0015] Preferably, in S4, the optimization of material parameters includes the diameter, wall thickness and laying thickness of the lightweight hollow spheres.

[0016] Preferably, in S4, the weight M1 of the upper layer of lightweight flame retardant material is calculated as shown in formula (1):

[0017]

[0018] Among them, ρ q is the density of the gradient density flame retardant layer material, the unit is g / L, d1 is the outer diameter of the lightweight hollow ball of the upper lightweight flame retardant material, the unit is mm, l1 is the wall thickness of the lightweight hollow ball of the upper lightweight flame retardant material, the unit is mm, and g is the gravity constant;

[0019] The weight M2 of the lower layer of lightweight flame retardant material is calculated as follows:

[0020]

[0021] Among them, ρ b is the transformer oil density, in g / L, d2 is the outer diameter of the lightweight hollow ball of the lower layer of lightweight flame retardant material, in mm, l2 is the wall thickness of the lightweight hollow ball of the lower layer of lightweight flame retardant material, in mm;

[0022] M1 and M2 satisfy equations (3) and (4):

[0023]

[0024] Combining equations (1) to (4) yields equation (5):

[0025]

[0026] Among them, 1.2d1≤d2≤2d1.

[0027] Preferably, in S4, after the outer diameter and wall thickness of the upper layer of light flame retardant material and the lower layer of light flame retardant material are determined, the heat transfer characteristics of the upper layer of light flame retardant material and the lower layer of light flame retardant material are compared with those of the traditional cobblestone layer to ensure that the heat dissipation is 100-150 times that of the cobblestone layer, thereby determining the optimal laying thickness, wherein the heat dissipation calculation formula is shown in formula (6):

[0028]

[0029] Where A is the surface area of ​​the upper light flame retardant material in contact with the air, in m 2 , ΔT is the temperature difference between the upper and lower surfaces of the upper light flame retardant material and the lower light flame retardant material, in °C, δ1 is the laying thickness of the upper light flame retardant material, in mm; δ2 is the laying thickness of the lower light flame retardant material, in mm; a n is the internal heat transfer coefficient of the gradient density flame retardant layer, the unit is W / (m 2 ·K); a w is the external heat transfer coefficient of the flame retardant layer, in W / (m 2 ·K); λ is the thermal conductivity of the material, the unit is W / (m·K);

[0030] According to formula (6), it can be deduced that the layered layout structure of lightweight flame retardant materials must satisfy formula (7):

[0031]

[0032] Where λ q is the thermal conductivity of lightweight materials, in W / (m·K); e is the thermal conductivity of pebbles, in W / (m·K); A1 is the surface area of ​​the upper light flame retardant material in contact with air, in m 2 ; A2 is the surface area of ​​the pebble layer in contact with the air, in m 2 ;

[0033] The calculation formula for the surface area A of the upper layer of light flame retardant material in contact with air is:

[0034]

[0035] Wherein, L is the length of the oil pit, in m, and D is the width of the oil pit, in m.

[0036] Therefore, the present invention adopts the above-mentioned layered layout structure and design method of the oil pit lightweight flame retardant material for electrical equipment, which has the following beneficial effects:

[0037] (1) The gradient density flame retardant layer uses lightweight hollow balls composed of hollow glass microspheres and flame retardant resin. The density gradient is formed by the difference in outer diameter of the upper and lower layers. The small-diameter hollow balls in the upper layer enhance local fire resistance, while the large-diameter hollow balls in the lower layer provide basic buoyancy, ensuring that the flame retardant layer floats stably on the oil surface and effectively blocks the spread of flames.

[0038] (2) The intelligent temperature control phase change layer absorbs heat through the solid-liquid phase change of the phase change material, slowing down the temperature rise rate. Combined with the thermal insulation properties of lightweight porous ceramics, it forms a double temperature control barrier to inhibit the spread of fire.

[0039] (3) The super-hydrophobic flame-retardant coating of the nano-coating protective layer can prevent oil accumulation and flames from rising, while protecting the underlying structure from high-temperature oxidation, further improving fire protection reliability;

[0040] (4) Through layered layout structural design and intelligent design methods, it has significant advantages in fire safety, lightweight, temperature control efficiency, etc.

[0041] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a structural schematic diagram of an embodiment of a layered layout structure and design method of a lightweight flame retardant material for an oil pit of electrical equipment according to the present invention.

[0043] Reference numerals

[0044] 1. Nano-coating protective layer; 2. Upper layer of lightweight flame-retardant material; 3. Lower layer of lightweight flame-retardant material; 4. Oil drain port; 5. Filter; 6. Oil pit; 7. Elastic support buffer layer; 8. Intelligent temperature control phase change layer. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0046] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0047] Example 1

[0048] like Figure 1 As shown, the present invention provides a layered layout structure of lightweight flame retardant materials for oil pits of electrical equipment, including an oil pit 6 and a layered barrier system. The layered barrier system is arranged in the oil pit 6. The layered barrier system is composed of an elastic support buffer layer 7, an intelligent temperature control phase change layer 8, a gradient density flame retardant layer and a nano-coating protective layer 1 from bottom to top.

[0049] The gradient density flame-retardant layer is made of lightweight hollow spheres composited with hollow glass microspheres and flame-retardant resin, with a mass ratio of 1:3. The gradient density flame-retardant layer comprises an upper layer of lightweight flame-retardant material 2 and a lower layer of lightweight flame-retardant material 3. These materials are identical but have different outer diameters. The larger hollow spheres in the lower layer of lightweight flame-retardant material 3 provide basic buoyancy, while the smaller hollow spheres in the upper layer of lightweight flame-retardant material 2 achieve a gradient buoyancy distribution through density differences, ensuring the flame-retardant layer floats stably on the oil surface and adapts to changes in oil level. The lower layer of lightweight flame-retardant material 3 is lightweight to reduce the overall load, while the upper layer of lightweight flame-retardant material 2 enhances local fire resistance and impact resistance through smaller particle size and higher density, protecting it from flames and oil fluctuations.

[0050] The elastic support buffer layer 7 is placed at the bottom of the oil pit 6 and is made of low-density elastic foam metal material with a density of 15-30 kg / m 3 When oil leaks or equipment failures cause oil impact, the elastic deformation absorbs energy, protecting the bottom structure of the oil pit 6 from damage. It also provides a uniform support base for the upper intelligent temperature control phase change layer 8, ensuring the stability of the entire layered structure.

[0051] The intelligent temperature-controlling phase-change layer 8 is composed of a composite of phase-change material and lightweight porous ceramic. The phase-change material has a phase-change temperature of 200-300°C. When the temperature in the oil pit 6 reaches this temperature, the phase-change material absorbs heat through a solid-liquid phase transition, slowing the temperature rise and suppressing the spread of fire. Furthermore, the high porosity of the lightweight porous ceramic reduces thermal conductivity, forming a dual thermal barrier in conjunction with the phase-change material.

[0052] The nano-coating protective layer 1 is coated with a nano-scale super-hydrophobic flame-retardant coating. Its nano-rough structure and low-surface-energy materials prevent oil from accumulating on the surface, reducing the risk of oil spreading in the event of a fire. The coating itself is flame-retardant, preventing flames from spreading upward while protecting the underlying structure from high-temperature oxidation.

[0053] Oil drain ports 4 are symmetrically located at the bottom of the oil pit 6, each equipped with a filter 5. During equipment maintenance or oil leaks, oil can be quickly drained through the ports 4, facilitating maintenance and cleaning. The filter 5 prevents solid impurities from entering the drain pipe, preventing blockage and protecting the lightweight materials in the layered structure from escaping.

[0054] The present invention also provides a method for designing a layered layout structure of a lightweight flame-retardant material for an oil pit of electrical equipment, comprising the following steps:

[0055] S1. Use computational fluid dynamics software to establish a three-dimensional numerical model M of the oil pit 6 fire scene;

[0056] S2. Setting different oil leakage amounts and fire temperature ambient temperatures to simulate working conditions and obtain temperature distribution data in the oil pit 6;

[0057] S3. Using the temperature distribution data obtained by simulation, a neural network model N is trained to establish a temperature prediction model P;

[0058] S4. Optimize the material parameters of the gradient density flame retardant layer based on P to achieve precise control of the temperature field in the oil pit 6 and achieve a flame retardant effect.

[0059] The three-dimensional numerical model M, the neural network model N and the temperature prediction model P are all existing technologies, except that the input and output parameter limits are different, so they will not be elaborated in detail.

[0060] In S4, the optimization of material parameters includes the diameter, wall thickness and laying thickness of the lightweight hollow spheres.

[0061] In S4, the weight M1 of the upper layer of lightweight flame retardant material 2 is calculated as shown in formula (1):

[0062]

[0063] Among them, ρ qis the density of the gradient density flame retardant layer material, in g / L, d1 is the outer diameter of the lightweight hollow ball of the upper lightweight flame retardant material 2, in mm, l1 is the wall thickness of the lightweight hollow ball of the upper lightweight flame retardant material, in mm, and g is the gravity constant;

[0064] The weight M2 of the lower layer of lightweight flame retardant material is calculated as follows:

[0065]

[0066] Among them, ρ b is the transformer oil density, in g / L, d2 is the outer diameter of the lightweight hollow ball of the lower layer of lightweight flame retardant material 3, in mm, l2 is the wall thickness of the lightweight hollow ball of the lower layer of lightweight flame retardant material, in mm;

[0067] M1 and M2 satisfy equations (3) and (4):

[0068]

[0069] Combining equations (1) to (4) yields equation (5):

[0070]

[0071] Among them, 1.2d1≤d2≤2d1.

[0072] After the outer diameter and wall thickness of the upper layer of light flame retardant material 2 and the lower layer of light flame retardant material 3 are determined, the heat transfer characteristics of the upper layer of light flame retardant material 2 and the lower layer of light flame retardant material 3 are compared with those of the traditional cobblestone layer to ensure that the heat dissipation is 100-150 times that of the cobblestone layer, thereby determining the optimal laying thickness. The heat dissipation calculation formula is shown in formula (6):

[0073]

[0074] Where A is the surface area of ​​the upper light flame retardant material 2 in contact with the air, in m 2 , ΔT is the temperature difference between the upper and lower surfaces of the upper light flame retardant material 2 and the lower light flame retardant material 3, in °C, δ1 is the laying thickness of the upper light flame retardant material 2, in mm; δ2 is the laying thickness of the lower light flame retardant material 3, in mm, a n is the internal heat transfer coefficient of the gradient density flame retardant layer, the unit is W / (m 2 ·K); a w is the external heat transfer coefficient of the flame retardant layer, in W / (m 2 ·K), λ is the thermal conductivity of the material, the unit is W / (m·K);

[0075] According to formula (6), it can be deduced that the layered layout structure of lightweight flame retardant materials must satisfy formula (7):

[0076]

[0077] Where λ q is the thermal conductivity of lightweight materials, in W / (m·K); e is the thermal conductivity of pebbles, in W / (m·K); A1 is the surface area of ​​the upper light flame retardant material 2 in contact with air, in m 2 ; A2 is the surface area of ​​the pebble layer in contact with the air, in m 2 ;

[0078] The calculation formula for the surface area A of the upper layer of lightweight flame retardant material 2 in contact with air is:

[0079]

[0080] Wherein, L is the length of the oil pit 6, in m, and D is the width of the oil pit 6, in m.

[0081] The parameters of the elastic support buffer layer 7, the intelligent temperature control phase change layer 8, and the nano-coating protective layer 1 are all measured and calculated using existing technologies to obtain the optimal parameters.

[0082] Example 1

[0083] The present invention provides a layered layout structure of lightweight flame-retardant materials for oil pits of electrical equipment, including an oil pit 6 and a layered barrier system. The layered barrier system is arranged in the oil pit 6. The layered barrier system comprises, from bottom to top, an elastic support buffer layer 7, an intelligent temperature control phase change layer 8, a gradient density flame-retardant layer and a nano-coating protective layer 1.

[0084] The oil pit 6 has a size of 10m×8m×2m, and has two symmetrical oil drain ports 4 with a diameter of 100mm at the bottom. A stainless steel filter screen 5 with a pore size of 2mm is provided at the oil drain ports 4.

[0085] The elastic support buffer layer 7 is selected with a density of 20kg / m 3 The closed-cell foam metal material is used as the base with a porosity of >85%. Its thickness is 50mm and it is modularly spliced. The size of a single module is 1m×1m. Concave and convex grooves are set on the edges to achieve seamless connection. It is fixed to the bottom of the oil pit by expansion bolts and the joints are filled with fireproof sealant.

[0086] The intelligent temperature-controlled phase change layer 8 has a thickness of 80 mm and a thermal conductivity of 0.12 W / (m·K).

[0087] The design method includes the following steps:

[0088] S1. Use computational fluid dynamics software to establish a three-dimensional numerical model M of the oil pit 6 fire scene;

[0089] S2. Setting different oil leakage amounts and fire temperature ambient temperatures to simulate working conditions and obtain temperature distribution data in the oil pit 6;

[0090] S3. Using the temperature distribution data obtained by simulation, a neural network model N is trained to establish a temperature prediction model P;

[0091] S4. Optimize the material parameters of the gradient density flame retardant layer based on P to achieve precise control of the temperature field in the oil pit 6 and achieve a flame retardant effect.

[0092] The three-dimensional numerical model M, the neural network model N and the temperature prediction model P are all existing technologies, except that the input and output parameter limits are different, so they will not be elaborated in detail.

[0093] In S4, the optimization of material parameters includes the diameter, wall thickness and laying thickness of the lightweight hollow spheres.

[0094] In S4, the weight M1 of the upper layer of lightweight flame retardant material 2 is calculated as shown in formula (1):

[0095]

[0096] Among them, ρ q is the density of the gradient density flame retardant layer material, in g / L, d1 is the outer diameter of the lightweight hollow ball of the upper lightweight flame retardant material 2, in mm, l1 is the wall thickness of the lightweight hollow ball of the upper lightweight flame retardant material, in mm, and g is the gravity constant;

[0097] The weight M2 of the lower layer of lightweight flame retardant material is calculated as follows:

[0098]

[0099] Among them, ρ b is the transformer oil density, in g / L, d2 is the outer diameter of the lightweight hollow ball of the lower layer of lightweight flame retardant material 3, in mm, l2 is the wall thickness of the lightweight hollow ball of the lower layer of lightweight flame retardant material, in mm;

[0100] M1 and M2 satisfy equations (3) and (4):

[0101]

[0102] Combining equations (1) to (4) yields equation (5):

[0103]

[0104] Among them, 1.2d1≤d2≤2d1.

[0105] After the outer diameter and wall thickness of the upper layer of light flame retardant material 2 and the lower layer of light flame retardant material 3 are determined, the heat transfer characteristics of the upper layer of light flame retardant material 2 and the lower layer of light flame retardant material 3 are compared with those of the traditional cobblestone layer to ensure that the heat dissipation is 100-150 times that of the cobblestone layer, thereby determining the optimal laying thickness. The heat dissipation calculation formula is shown in formula (6):

[0106]

[0107] Where A is the surface area of ​​the upper light flame retardant material 2 in contact with the air, in m 2 , ΔT is the temperature difference between the upper and lower surfaces of the upper light flame retardant material 2 and the lower light flame retardant material 3, in °C, δ1 is the laying thickness of the upper light flame retardant material 2, in mm; δ2 is the laying thickness of the lower light flame retardant material 3, in mm, a n is the internal heat transfer coefficient of the gradient density flame retardant layer, the unit is W / (m 2 ·K); a w is the external heat transfer coefficient of the flame retardant layer, in W / (m 2 ·K), λ is the thermal conductivity of the material, the unit is W / (m·K);

[0108] According to formula (6), it can be deduced that the layered layout structure of lightweight flame retardant materials must satisfy formula (7):

[0109]

[0110] Where λ q is the thermal conductivity of lightweight materials, in W / (m·K); e is the thermal conductivity of pebbles, in W / (m·K); A1 is the surface area of ​​the upper light flame retardant material 2 in contact with air, in m 2 ; A2 is the surface area of ​​the pebble layer in contact with the air, in m 2 ;

[0111] The calculation formula for the surface area A of the upper layer of lightweight flame retardant material 2 in contact with air is:

[0112]

[0113] Wherein, L is the length of the oil pit 6, in m, and D is the width of the oil pit 6, in m.

[0114] When lightweight hollow balls are selected as the flame retardant material in this embodiment, it can be calculated according to formula (5) and formula (7) that when the wall thickness of the two lightweight hollow balls is designed to be the same as the laying thickness, and 0.3mm≤l1=l2≤0.5mm, the outer diameter of the lightweight hollow balls of the upper layer of lightweight flame retardant material 2 should be 17.5mm≤d1≤42mm, and the outer diameter of the lightweight hollow balls of the lower layer of lightweight flame retardant material 3 should be 35mm≤d2≤52mm, and the laying thickness of the gradient density flame retardant layer should be 75mm≤δ1=δ2≤100mm.

[0115] In this embodiment, the wall thickness of the two layers of lightweight hollow balls, the upper layer of lightweight flame retardant material 2 and the lower layer of lightweight flame retardant material 3, are both 0.4 mm, the upper layer diameter is 38 mm, the lower layer diameter is 50 mm, the total laying thickness is 200 mm, and the thickness of the upper and lower layers is both 100 mm.

[0116] Comparative Example 1

[0117] The only difference between this comparative example and Example 1 is that the gradient density flame retardant layer is made of stainless steel hollow metal balls. Other conditions are the same as those in Example 1.

[0118] Comparative Example 2

[0119] The only difference between Comparative Example 2 and Example 1 is that the gradient density flame retardant layer uses crushed stone type artificial light aggregate, does not adopt a layered layout, its particle size is uniform and controllable, and it has excellent fire resistance and heat insulation performance. It is A1 grade non-combustible, has a water absorption rate of about 5%, is corrosion-resistant, and weighs 400-500kg / m 3 , cylinder pressure strength of 1.5Mpa, etc., it can adapt to severe cold and heat and rain erosion or soaking, and meet the 50-year design service life requirement of the substation. The particles in this comparative example have a particle size of 38mm and a laying thickness of 200mm.

[0120] Example 1, Comparative Examples 1 and 2 were applied to actual transformer oil combustion and tested by arranging thermocouples. The conclusions are as follows: in Example 1, the maximum temperature of the flame is continuously maintained at 1200°C, the maximum temperature of the transformer oil burning at the bottom of the layered layout structure of the lightweight flame retardant material can reach about 1200°C, and the external ambient temperature above is generally between -20°C and 40°C, the temperature difference is between 1160°C and 1220°C, and the overflow fire flows into the oil pit 6 and does not submerge the gradient density flame retardant layer.

[0121] In Comparative Example 1, the flame temperature rose to 800°C within 2 minutes, reaching a maximum temperature of 812°C. As the overflow oil level rose, the temperature probe gradually submerged below the stainless steel hollow metal ball and the oil level, and the temperature dropped to around 120°C within 2 minutes. In Comparative Example 2, the flame reached a maximum temperature of 370°C, and after the overflow fire stopped within 5 minutes, the temperature remained at 180°C.

[0122] In summary, the layered layout structure of Example 1 has good flame retardant and fire isolation effects and can quickly reduce the temperature above the oil surface.

[0123] Therefore, the present invention adopts the above-mentioned layered layout structure and design method of lightweight flame-retardant materials for the oil pit of electrical equipment. By optimizing the layered layout structure and design method of flame-retardant materials, the overall fire resistance and safety of the oil pit are effectively improved, while reducing the engineering construction and operation and maintenance costs.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment, characterized by: It includes an oil pit and a layered barrier system. The layered barrier system is arranged in the oil pit. From bottom to top, the layered barrier system consists of an elastic support buffer layer, an intelligent temperature control phase change layer, a gradient density flame retardant layer and a nano-coating protective layer.

2. The layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 1, characterized in that: The gradient density flame retardant layer is made of lightweight hollow balls composited with hollow glass microspheres and flame retardant resin. The gradient density flame retardant layer includes an upper layer of lightweight flame retardant material and a lower layer of lightweight flame retardant material. The upper layer of lightweight flame retardant material and the lower layer of lightweight flame retardant material are made of the same material but have different outer diameters.

3. The layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 1, characterized in that: The elastic support buffer layer is placed at the bottom of the oil pit. It is a low-density elastic foam metal material with a density of 15-30kg / m 3 .

4. The layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 1, characterized in that: The intelligent temperature-controlled phase change layer is composed of a composite of phase change material and lightweight porous ceramics. The phase change temperature of the phase change material is 200-300°C.

5. The layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 1, characterized in that: The surface of the nano-coating protective layer is coated with a nano-scale super-hydrophobic flame-retardant coating.

6. The layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 1, characterized in that: There are symmetrical oil drain ports at the bottom of the oil pit, and filters are installed at the oil drain ports.

7. A method for designing a layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Use computational fluid dynamics software to build a three-dimensional numerical model M of the oil pit fire scene; S2. Set different oil leakage amounts and fire temperature ambient temperatures to simulate working conditions and obtain temperature distribution data in the oil pit; S3. Using the temperature distribution data obtained by simulation, a neural network model N is trained to establish a temperature prediction model P; S4. Based on P, the material parameters of the gradient density flame retardant layer are optimized to achieve precise control of the temperature field in the oil pit and achieve a flame retardant effect.

8. The method for designing a layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 7, characterized in that: In S4, the optimization of material parameters includes the diameter, wall thickness and laying thickness of the lightweight hollow spheres.

9. The method for designing a layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 7, characterized in that: In S4, the weight M1 of the upper layer of lightweight flame retardant material is calculated as shown in formula (1): Among them, ρ q is the density of the gradient density flame retardant layer material, the unit is g / L, d1 is the outer diameter of the lightweight hollow ball of the upper lightweight flame retardant material, the unit is mm, l1 is the wall thickness of the lightweight hollow ball of the upper lightweight flame retardant material, the unit is mm, and g is the gravity constant; The weight M2 of the lower layer of lightweight flame retardant material is calculated as follows: Among them, ρ b is the transformer oil density, in g / L, d2 is the outer diameter of the lightweight hollow ball of the lower layer of lightweight flame retardant material, in mm, l2 is the wall thickness of the lightweight hollow ball of the lower layer of lightweight flame retardant material, in mm; M1 and M2 satisfy equations (3) and (4): Combining equations (1) to (4) yields equation (5): Among them, 1.2d1≤d2≤2d1.

10. The method for designing a layered layout structure of lightweight flame-retardant materials for oil pits in electrical equipment according to claim 7, characterized in that: In S4, after the outer diameter and wall thickness of the upper and lower layers of light flame retardant materials are determined, the heat transfer characteristics of the upper and lower layers of light flame retardant materials are compared with those of the traditional cobblestone layer to ensure that the heat dissipation is 100-150 times that of the cobblestone layer, thereby determining the optimal laying thickness. The heat dissipation calculation formula is shown in formula (6): Where A is the surface area of ​​the upper light flame retardant material in contact with the air, in m 2 , ΔT is the temperature difference between the upper and lower surfaces of the upper light flame retardant material and the lower light flame retardant material, in °C, δ1 is the thickness of the upper light flame retardant material, in mm, δ2 is the thickness of the lower light flame retardant material, in mm, a n is the internal heat transfer coefficient of the gradient density flame retardant layer, the unit is W / (m 2 K), a w is the external heat transfer coefficient of the flame retardant layer, in W / (m 2 ·K); λ is the thermal conductivity of the material, the unit is W / (m·K); According to formula (6), it can be deduced that the layered layout structure of lightweight flame retardant materials must satisfy formula (7): Where λ q is the thermal conductivity of lightweight materials, in W / (m·K); e is the thermal conductivity of pebbles, in W / (m·K); A1 is the surface area of ​​the upper light flame retardant material in contact with air, in m 2 ; A2 is the surface area of ​​the pebble layer in contact with the air, in m 2 ; The calculation formula for the surface area A of the upper layer of light flame retardant material in contact with air is: Wherein, L is the length of the oil pit, in m, and D is the width of the oil pit, in m.

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