Multilayer container of liquid nitrogen for use in firefighting

Abstract

The proposed device is a preferably cylindrical container with two containing elements, one inside the other, with a vacuum layer therebetween and an external insulating layer, wherein the first containing element holds liquid nitrogen. The device is designed to withstand the low temperature of the cryogenic liquid on the inside while withstanding the high temperature of fires on the outside. Both ends, cover and base, are preferably semispherical, with one end comprising a non-hermetic closure system.

Description

Multi-layer container for liquid nitrogen for use in fire extinguishing.

[0001] The present invention pertains to the field of fire extinguishing devices. Specifically, it consists of a container design capable of storing a cryogenic liquid, such as liquid nitrogen, and that this liquid can be safely used as an extinguishing agent.

[0002] Liquid nitrogen is primarily used to extinguish fires in underground and / or mining environments, especially in enclosed spaces. While its potential benefits for other types of fires are currently hampered by several critical issues.

[0003] Among the benefits of using liquid nitrogen as an extinguishing agent, it is worth noting that it is environmentally friendly and does not harm the environment. It rapidly reduces the oxygen concentration in the confined space and eventually smothers the fire. Gaseous nitrogen in high-temperature areas does not decompose during fire suppression and does not react with other substances. Therefore, no traces remain after the fire is extinguished. Summary of the Invention:

[0004] The invention consists of a multi-layered container comprising two inner containers: a first container inside a second container, with a vacuum layer between them. The first container holds liquid nitrogen. The second container, which contains the first, is directly coated with an insulating layer. This design allows the container to maintain a low internal temperature while remaining suitable for use at high temperatures on a fire, without discharging its contents before reaching the desired location. Depending on the size of the fire, one or more containers may be required. Upon reaching the fire, these containers rupture, dispersing the nitrogen and extinguishing the fire. Technical Problem:

[0005] The use of liquid nitrogen as an extinguishing agent is currently limited to enclosed areas, since its use in other fires presents at least the following drawbacks:

[0006] Losses of liquid nitrogen content through evaporation.

[0007] Expansion of the cryogenic contents by changing from a liquid to a gaseous state, which could cause an explosion due to the increase in internal pressure, if the container is hermetically sealed.

[0008] When used in enclosed spaces, by displacing the oxygen available in the air, there is a risk of suffocation if not handled by a specialist.

[0009] Handling and exposure to cryogenic liquid, when it comes into contact with a very low temperature, causes severe burns on contact.

[0010] To maintain a low temperature inside the container while also resisting high temperatures when it reaches the fire. Solution to the problem:

[0011] The device of the invention was designed to withstand both the temperature difference with respect to that of liquid nitrogen of -196° Celsius, up to the average temperatures of a fire, as well as to withstand the pressure that will be generated inside the container when the liquid nitrogen evaporates during the exposure period. Advantageous effects of the invention:

[0012] The device of the invention allows the use of liquid nitrogen in all types of fires, given its design that allows it to withstand the described temperature difference, thus ensuring that the contents of the device are released at the desired time and place. Brief Description of the Figures:

[0013] It shows a cross-section of the container of the invention, where: 1A shows the first container, 1B shows the second container, 1C shows the external insulating cover, 1D shows the vacuum layer, 1E shows the inlet for the liquid, 1F shows the non-hermetic closure system, 1G shows the liquid nitrogen. Detailed description of the invention:

[0014] The device of the invention consists of a preferably cylindrical multilayer container that has two containers, one inside the other, with a vacuum layer between them and an insulating material covering on the outside.

[0015] The materials selected for the manufacture of the device must withstand both low temperatures, such as that of liquid nitrogen, -196° Celsius, and the high temperatures of fires.

[0016] The device is preferably cylindrical with two hemispherical end caps (lid and base), as shown in Figure 1. These caps can be of varying sizes to accommodate different volumes and have sufficient thickness to withstand internal and external pressures. The first container withstands a maximum pressure of 5 bar, considering the internal pressure generated by the liquid nitrogen as it expands into a gas and the pressure of the external vacuum layer. The second container withstands a pressure of one atmosphere, equivalent to approximately 1.01 bar, and is covered by an insulating layer. This layer ensures that the maximum temperature inside the second container does not exceed the material's critical temperature during use, while also making the entire device resistant to high fire temperatures.

[0017] Liquid nitrogen volumes can vary from 0.1 L to 10 L depending on the application, with larger volumes being suitable for forest fires and smaller volumes for urban fires. The volume of the first container should be at least 50% larger than the liquid nitrogen it will hold. For smaller volumes, this space should be extended, even exceeding 100% of the liquid nitrogen, to prevent an increase in pressure within the first container.

[0018] According to the invention, the volume values ​​and calculations will vary depending on the material used. The critical pressure exerted by the liquid nitrogen on the material of the first container must be taken into account. The calculations are subject to change due to the inherent characteristics of these materials and other possible variations. In any case, the internal critical pressure must be respected; for a smaller volume, a lower percentage of liquid nitrogen should be used.

[0019] The thickness estimates for the first container can vary, but a range of 1.5 mm to 10 mm is preferred, depending on the container's volume. The thickness of the second container can range from 0.5 mm to 5 mm. The insulating layer can also vary in thickness, from 5 mm to 50 mm. The other dimensions of the container—its length and diameter—were calculated based on the length of the cylinder plus the end caps, preferably hemispherical, for the total length of the device. The estimated cylinder lengths range from 5 to 20 cm, depending on the volume, and the total lengths range from 10 to 45 cm, respectively. The internal diameters were calculated from the desired volume and the stipulated length of the internal volume. Then, using the required thicknesses, the external diameters of the device were calculated, which range from 10 to 20 cm.These last diameters correspond to the external diameter of the insulator.

[0020] With the described device of the invention, by using one or more containers, liquid nitrogen is made to reach the burning core, where the container breaks and the liquid nitrogen expands, suffocating it.

[0021] Possible materials to use are: glass, ceramic, and fibers made from these materials. Glass or ceramic is preferred for the containers, primarily borosilicate glass 3.3. The insulating material covering the second container is preferably ceramic.

Claims

Multilayer container characterized by comprising two temperature and pressure resistant containers, one inside the other, with a vacuum layer between them, an insulating material covering on the outside and a non-hermetic closure at one of its ends. The container of claim 1, wherein the first container has a thickness of 1.5 mm to 10 mm. The container of claim 1, wherein the second container has a thickness of 0.5 mm to 5 mm. The container of claim 1, wherein the outer insulating layer has a thickness of 5 mm to 50 mm. The container of claims 1 to 4, wherein the first and second containers are made of borosilicate glass 3.3 or ceramic and the insulating material covering the second container is ceramic or ceramic fiber or glass fiber. The container of claims 1 to 5, wherein both containers are cylindrical in shape and the ends are hemispherical in shape.

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