Structure for improving fire safety of closed interlayer type combustible material

Abstract

The invention discloses a structure for improving fire safety of a closed sandwich type combustible material. The structure comprises an outer closed structure layer, a combustible functional material layer, a fireproof layer and a flame-retardant plate. The surface of the combustible functional material layer is designed to be equidistant wave-shaped, protruding parts of the combustible functional material layer are subjected to fireproof flame-retardant treatment, a fireproof flame-retardant plate is arranged in the material layer and perpendicular to the outer structural layer, and a fireproof layer is arranged on the outer side to cover the protruding parts to jointly form a fireproof treatment structure. When fire hazards occur, local vortexes can be formed on the surface of the wave-shaped structure, flow resistance is increased, the chimney effect is restrained, and the flame diffusion speed is reduced. And on the other hand, the fireproof flame-retardant plate covers and protects flammable and easily-damaged parts and supports an external structural layer, the overall structural strength is improved, structural damage and vertical diffusion of flames are hindered, and the overall fireproof performance of the structure is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of material fire safety, in particular to a structure for improving the fire safety of closed sandwich combustible materials, which is suitable for fireproof design of structures with narrow cavities, such as building exterior wall roof insulation, vehicle cabin wall, etc. BACKGROUND

[0002] In order to meet the needs of industry, commerce and personnel comfort, there are a large number of closed sandwich structures in building structures and vehicle designs, such as building exterior wall insulation structure, vehicle interior, high-speed rail car side wall, aircraft cargo compartment lining, spacecraft cabin wall, etc. The sandwich structure is mostly in the form of combination of non-combustible structure layer and internal combustible insulation material, which has the advantages of lightness, heat insulation, sound insulation, etc.

[0003] However, according to numerous fire accident cases and investigation reports, such as the Grenfell Tower fire in London in 2017, the ICE train fire in Germany in 2018, and the high-rise residential fire in Shanghai in 2010, many fire cases show that the sandwich type confined space structure has great fire safety hidden danger. There is an air layer between the external structure of the sandwich type confined space and the internal combustible material layer, forming a narrow gap. Investigation and research show that the narrow vertical channel formed by the parallel sandwich is prone to form a chimney effect. Once a fire occurs, the outer closed structure will deform under high temperature, and the flame will overflow into the sandwich, which will spread vertically rapidly, and its spreading speed is much faster than that of flame spreading in open space. In addition, the heat loss in the closed space is reduced, which accelerates the pyrolysis of combustible materials, further intensifies the burning intensity and releases toxic gases, causing major fire accidents, endangering life and property safety.

[0004] In the existing technical solutions, rock wool, mineral wool, glass wool and other completely non-combustible materials can be used to replace the combustible materials in the sandwich type confined space. The advantage is that it can inhibit ignition to a certain extent, but the cost is higher than that of ordinary materials, and it can only temporarily suppress fire, and will fail in long-term fire, which cannot solve the fundamental problem of chimney effect. In addition, some experts and scholars point out that the design of increasing ventilation openings can effectively block the fire, but the setting of ventilation openings will damage the structural continuity and affect the heat insulation performance; if not properly applied, it will instead provide oxygen supply and accelerate combustion. At the same time, the opening design will damage the strength of the structure itself, making the structure more prone to deformation and damage under high temperature conditions. In summary, the existing technology cannot balance the structural integrity and strength, and cannot balance the economy and flame retardant function, and there is an urgent need for technical means to inhibit the chimney effect and control the synergistic effect of material pyrolysis. SUMMARY

[0005] Based on the above problems, the application provides a structure for improving fire safety of a closed sandwich type combustible material, which increases flow resistance of a flame flow field, suppresses a chimney effect and improves fire safety of the structure through surface structure optimization design and a fire retardant plate structure.

[0006] A structure for improving fire safety of a closed sandwich type combustible material, characterized by comprising an outer closed structure layer, a combustible functional material, a fireproof layer and a fire retardant plate.

[0007] The combustible functional material layer is sandwiched by the outer closed structure layer in a horizontal direction and together forms a sandwich type sandwich structure, and a hollow air layer is arranged in the sandwich structure; a contact surface of the combustible functional material layer and the air layer is designed as a wave structure, and the convex part surface of the wave structure is provided with the fireproof layer.

[0008] The fire retardant plate is arranged perpendicularly to the outer closed structure layer and penetrates the combustible functional material layer, and two ends thereof are respectively connected to the convex part surface of the wave structure and the inner surface of the outer closed structure layer.

[0009] Preferably, the air layer is arranged between the combustible functional material layer and the outer closed structure layer or inside the combustible functional material, and the number of layers of the hollow air layer is arranged according to a material use situation and sealing requirement.

[0010] Preferably, the cross-sectional shape of the wave structure is one of a sinusoidal curve, a triangular wave or a trapezoidal wave.

[0011] Preferably, the wave structure is an equidistant continuous wave, the vertical distance between adjacent wave crests is 1-3 cm, and the distance between the wave crest and the wave trough in the horizontal direction is 0.3-1 cm.

[0012] Preferably, the fireproof layer completely covers the wave crest of the combustible functional material layer, that is, more than 40% of the area of the region spreading from the wave crest vertex to both sides of the wave trough.

[0013] Preferably, the fireproof layer is made of a fire retardant material or a fireproof paint.

[0014] Preferably, the fire retardant material is a fire extinguishing agent, an intumescent paint or a non-combustible metal material.

[0015] Preferably, the fire retardant plate is made of various A-grade non-combustible materials or B1-grade difficult-to-combust materials.

[0016] Preferably, the fire retardant plate is additionally provided with a fire retardant.

[0017] The application has the following beneficial effects:

[0018] The application discloses a structure for improving fire safety of closed sandwich combustible material, which is characterized in that: on one hand, by changing the surface structure of the combustible material between the sandwich, local vortex is formed by the wavy surface to enhance the airflow resistance, suppress the chimney effect and delay the flame propagation; on the other hand, the fireproof layer and the fire-retardant board are introduced to separate the continuous combustible material and block the flame propagation path, thereby improving the fireproof performance, enhancing the structural strength and stability. In summary, the application is not simply replaced by the material, but through the innovative structural design, the fire safety performance is greatly improved while the original advantages of the sound insulation and heat preservation of the combustible material are retained. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced.

[0020] Figure 1 FIG. 1 is a sectional view of the structure for improving fire safety of closed sandwich combustible material of the application;

[0021] Figure 2 FIG. 2 is a comparison of the flame base and the flame front position of the sectional view of the original structure and the structure of the application;

[0022] Figure 3 FIG. 3 is a comparison of the sectional flame temperature cloud chart of the original structure and the structure of the application at the 5th second;

[0023] Figure 4 FIG. 4 is a streamline diagram of the flow field when the flame root moves to the top of the wavy structure of the application. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the application more clear, the application will be further described in detail below by combining with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0025] As Figure 1As shown, the application discloses a structure for improving fire safety of closed sandwich combustible material, which comprises an outer closed structure layer, a combustible functional material layer, a fireproof layer and a fireproof board. The combustible functional material is located between the outer closed structure layers and forms a sandwich structure together with the outer closed structure layers on both sides. A hollow air layer is arranged in the sandwich structure and can be arranged between the combustible functional material layer and the outer closed structure layer or in the combustible functional material. According to the use situation and sealing requirement of the material, multiple air layers can be arranged. In the embodiment, the air layer for air flow is formed between the combustible functional material layer and the outer closed structure layer, and the side of the combustible functional material layer facing the air layer is designed as a wave-shaped structure; the other side is connected with the outer closed structure layer. The cross-sectional shape of the wave-shaped structure is one of a sinusoidal curve, a triangular wave or a trapezoidal wave, and the wave-shaped structure is an equidistant continuous wave, the vertical distance between adjacent wave crests is 1-3 cm, and the distance between the wave crest and the wave trough in the horizontal direction is 0.3-1 cm. The fireproof layer covers the surface protrusions of the wave-shaped structure and is connected with the internal fireproof board. The fireproof board penetrates the combustible material layer and is perpendicular to the structure layer and the material layer.

[0026] The fireproof board is arranged transversely through the combustible functional material layer and has a length not shorter than the maximum thickness of the combustible material. The two ends are respectively connected with the inner surface of the outer closed structure layer and the inner surface of the wave-shaped surface protrusion center of the combustible functional material layer (i.e. the inner surface of the wave crest of the wave-shaped structure). In the embodiment, the "inner surface of the wave-shaped surface protrusion center" is the side away from the air layer. The fireproof layer completely covers more than 40% of the area near the wave crest of the combustible functional material layer. The fireproof layer is made of fire extinguishing agent, intumescent coating or non-combustible metal material and other fire-retardant materials or fireproof coating. The fireproof board is made of various A-grade non-combustible materials or B1-grade difficult-to-combust materials and added with fire retardant.

[0027] When a fire occurs at the bottom of the outer wall, the flame and high-temperature gas enter the air layer of the sandwich structure and tries to spread upward rapidly. When the high-temperature airflow flows through the wave-shaped surface, the flow line is sharply bent, the flow resistance is significantly increased, and the strength of the chimney effect is effectively inhibited. The fireproof board divides the continuous combustible material into discrete intervals, blocks the path of the flame upward propagation, supports the outer closed structure layer under high temperature, delays the deformation and damage of the outer closed structure layer, and prevents the flame from overflowing into the sandwich structure. The fireproof layer covers the protruding part of the wave-shaped surface and focuses on protecting the part most easily impacted by the flame. The fireproof layer is connected with the fireproof board. After the surface of the fireproof layer material is damaged, the fireproof board is exposed, the fire retardant is released, and a complete fireproof treatment system is formed.

[0028] In order to better describe the technical gain of the structure design of the application for improving the fire safety of the closed sandwich combustible material, the flow field in the structure layer of the application is predicted and analyzed by using the method of calculating flame dynamics simulation. The specific description is as follows:

[0029] A commonly used closed sandwich structureFigure 1 As shown, according to the method for improving the fire safety of the material, the surface structure of the combustible functional material is changed, the fireproof layer and the fire-retardant plate are added.

[0030] The average thickness of the combustible functional material is 7 cm, the vertical interval of adjacent convex peaks of the wavy surface is 2.5 cm, and the convex peak and the concave bottom are 0.7 cm apart in the horizontal direction. The fire-retardant plate is horizontally placed at the peak of the wave, connected with the fireproof layer and penetrating the combustible material layer, with a length of 7 cm and a thickness of 10 mm. The convex part of the wavy surface of the combustible material covers the fireproof layer, and the fireproof layer completely covers 40% of the area near the wave peak of the material layer, with a covering thickness of 2 mm.

[0031] In order to compare the effect of the closed sandwich structure proposed in the present application on improving the fire safety, numerical simulation models are established based on the traditional sandwich structure and the material structure of the method of the present application. Except for the different material structures, the rest of the calculation settings are the same.

[0032] Figure 2 For comparison of the flame length of the present application and the original structure, it can be seen that the position of the flame tip of the wavy surface treatment is lower than that of the flat material flame tip, and the root position is low, the propagation speed is slow, and the flame length is shorter. In addition, the lower part of the flat sample gradually pyrolyzes upward to the end of the fuel as the flame burns, causing large damage to the combustible material layer and accelerating the propagation of the flame; in contrast, the intensity of the wavy surface flame decreases in the later stage, the flame tip retreats, the length rapidly decreases and eventually extinguishes in the middle of the fuel, thereby reducing the fire hazard.

[0033] Figure 3 For comparison of the flame temperature cloud map of the present application and the original structure at 5s, the black solid line area in the figure represents the flame core, and it can be seen that the flame propagation speed is slower and the flame length is reduced after the surface of the material is treated with waves. In the flat structure, the flame will appear a relatively strong entrainment phenomenon when it spreads upward, forming a plume and intensifying the chimney effect, making the flame spread more violently, and the flame core temperature reaches 1600℃; after changing the surface structure of the combustible functional material, the flame length of the hollow air layer is greatly shortened compared with the traditional structure, the flame core temperature is basically maintained below 1100℃, the flame propagation speed is reduced, and the chimney effect is inhibited.

[0034] Figure 4For the streamline diagram of the flow field when the flame root moves to the top of the wave structure, it can be further seen that the possibility of fluid impacting the wall surface is increased after the surface of the combustible functional material is changed to the wave structure. When the fluid flows through the wave surface, due to the action of buoyancy, obvious undulating fluctuations and streamline bending occur. The bending of the flame leads to an increase in the contact area between the structure and the external air, and an increase in heat loss. At the same time, in the flame depression, the local vortex generated will form a turbulent flow generation area, so that the laminar layer is destroyed, and a larger disturbance occurs. The convex structure will hinder the transport of oxygen, leading to a further reduction in the intensity and temperature of the flame, thereby limiting the upward spread of the flame.

[0035] In addition, the fire-retardant plate inside the combustible material further serves the purpose of fire prevention. When the material gradually pyrolyzes and exposes the fire-retardant plate, it is difficult for the flame to ignite, which reduces the pyrolysis speed of the material and blocks the transport of oxygen, so that the flame consumes a large amount of heat energy when it jumps over the fire-retardant plate, reduces the flame propagation rate, further reduces the impact of the fire, and increases the rescue time.

[0036] In summary, by changing the surface structure of the combustible functional material, adding a fireproof layer and a fire-retardant plate, the length of the flame during combustion is greatly shortened, the chimney effect is inhibited, and the safety of the closed sandwich structure during a fire is improved.

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A structure for improving fire safety of a closed sandwich combustible material, characterized by, The outer closed structure layer, the combustible functional material layer, the fireproof layer and the fire-retardant plate are included. The combustible functional material layer is sandwiched by the outer closed structure layer in horizontal direction and forms a sandwiched structure together, and a hollow air layer is arranged inside the sandwiched structure; a contact surface of the combustible functional material layer and the air layer is designed as a wave structure, and an outer surface of a convex part of the wave structure is provided with the fireproof layer. The fire-retardant plate is arranged perpendicularly to the outer closed structure layer and penetrates the combustible functional material layer, and two ends thereof are respectively connected to a surface of the convex part of the wave structure and an inner surface of the outer closed structure layer.

2. The structure for improving fire safety of a closed sandwich combustible material according to claim 1, wherein The air layer is arranged between the combustible functional material layer and the outer closed structure layer or inside the combustible functional material layer, and the number of layers of the hollow air layer is arranged according to a material use situation and sealing requirement.

3. The structure for improving fire safety of a closed sandwich combustible material according to claim 1, wherein A cross-sectional shape of the wave structure is one of a sinusoidal curve, a triangular wave or a trapezoidal wave.

4. The structure for improving fire safety of a closed sandwich combustible material according to claim 1 or 3, wherein The wave structure is an equidistant continuous wave structure, a vertical distance between adjacent wave crests is 1-3 cm, and a distance between the wave crest and the wave trough in the horizontal direction is 0.3-1 cm.

5. The structure for improving fire safety of a closed sandwich combustible material according to claim 1, wherein The fireproof layer completely covers more than 40% of an area near the wave crest of the combustible functional material layer.

6. The structure for improving fire safety of a closed sandwich combustible material according to claim 1 or 5, wherein The fireproof layer is made of a fire-retardant material or a fireproof paint.

7. The structure for improving fire safety of a closed sandwich combustible material according to claim 6, wherein The fire-retardant material is a fire extinguishing agent, an intumescent paint or a non-combustible metal material.

8. The structure for improving fire safety of a closed sandwich combustible material according to claim 1, wherein The fire-retardant plate is made of various A-grade non-combustible materials or B1-grade difficult-to-combust materials.

9. The structure for improving fire safety of a closed sandwich combustible material according to claim 8, wherein The fire-retardant plate is additionally provided with a fire retardant.

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