Method and device for extinguishing a fire on an object

Abstract

A method for extinguishing a fire on an object (20, 30), the method comprising the following steps: - providing a container (11) containing a solid granulate (12) of loose solid particles, - creating a fluidized bed (17) within the container (11) filled with the solid granulate (12) by introducing a gaseous fluid into the solid granulate (12) in such a way that the burning object (20, 30) sinks at least partially into the fluidized bed (17), - wherein the object (20, 30) is introduced into the container (11) before or after the creation of the fluidized bed (17), and - stopping the introduction of the gaseous fluid into the container (11) when the burning object (20, 30) has sunk at least partially into the fluidized bed (17) in order to stop the generation of the fluidized bed (17) and to embed the sunken object (20, 30) at least partially in the solid granulate (12).

Description

[0001] The invention relates to a method for extinguishing a fire on an object. The invention also relates to a device for this purpose.

[0002] Extinguishing a fire can be more or less difficult depending on the nature of the burning material. Especially when a multitude of different chemical elements and compounds are present, extinguishing a fire involving such a mixture of materials requires special measures to extinguish the fire safely and completely, while minimizing personal injury and property damage.

[0003] Recently, the number of lithium-ion batteries (especially rechargeable batteries) has been steadily increasing due to the increasing number of mobile devices used in everyday life. Due to their high energy density and largely nonexistent memory effect, such lithium-ion batteries are used in a wide variety of products, such as mobile phones (smartphones, cell phones), headphones, laptops, tools, electric scooters, electric bicycles, and now also in large numbers in electric cars.

[0004] However, such lithium-ion batteries have the disadvantage that their chemical composition can react extremely violently with many substances and are also prone to overheating, meaning they can quickly catch fire. Therefore, such lithium-ion batteries are generally classified as hazardous goods.

[0005] At temperatures above 69 °C, the solid electrolyte interphase (the interface between the anode and electrolyte) begins to decompose, followed by exothermic reactions between the anode and electrolyte, as well as between the anode material and the binder. This is followed by separator melting, electrolyte decomposition, and reactions between the cathode material and the electrolyte. All of these reactions release increasing amounts of heat. A chain reaction can occur if the cell is not actively cooled. This is also referred to as thermal runaway.

[0006] During thermal runaway in a lithium-ion battery, the electrolyte and separator, in the presence of oxygen, can contribute significantly to heat release due to their ignition and combustion properties. In a battery consisting of multiple cells, this effect also affects neighboring cells. Therefore, it can lead to the destruction of an entire battery consisting of several individual cells (lithium-ion battery cells).

[0007] Triggers for such thermal runaway are generally divided into four categories. The first category is an internal short circuit. An internal short circuit occurs when the separator fails, causing a short circuit between the electrodes and thus thermal runaway. This can occur due to a misuse condition or as a result of a manufacturing defect. The second category is improper use (overcharging, deep discharging). Overcharging or deep discharging to voltages beyond the manufacturer's specified voltage limits can lead to lithium plating or dendrite formation on the anode. Over time, this can penetrate the separator, resulting in a short circuit between the electrodes and thermal runaway.The third category is thermal overload, where a cell temperature of 70°C or higher can directly lead to thermal runaway. Mechanical damage (penetration by objects, pinching, or bending of the cell), the fourth category, can ultimately lead to a short circuit between the electrodes and thus to thermal runaway.

[0008] If one of the above-mentioned cases leads to thermal runaway of the cell and thus to a fire in the cell or battery, the fire cannot be completely extinguished by excluding oxygen, as the cathodes decompose at high temperatures and release oxygen in the process. However, fires in which the cathode has not yet decomposed can be extinguished, which can delay the thermal runaway.

[0009] A further risk arises from the gases produced when the electrolyte decomposes. This includes hydrocarbons, carbon monoxide, hydrogen fluoride, and hydrogen, which can form an explosive mixture with oxygen.

[0010] To completely extinguish a cell or battery fire, the flames must be extinguished, the explosive environment prevented, and the cell or battery cooled. Cooling is especially important for batteries with many individual cells, as it can prevent thermal runaway in neighboring cells.

[0011] Various extinguishing agents are available to extinguish such fires, including water, dry powder, CO2, and foam. The use of water as an extinguishing agent is recommended, as cooling the cells is particularly important.

[0012] From DE 20 2020 102 574 U1, for example, an extinguishing lance for extinguishing burning electrical equipment is known in order to apply the extinguishing agent to the correct location, even in the case of large batteries in which the cells are arranged in a housing.

[0013] However, after extinguishing the battery, it can flare up again. This can be due to a lack of cooling after the extinguishing attempt or to further internal short circuits in the battery due to damage caused by the fire or the extinguishing attempt. The remaining stored energy in the cells can also repeatedly lead to thermal runaway due to the short circuits.

[0014] DE 102016 211 854 B3 discloses a container for recovering a damaged electric vehicle. The container has a container base and several side walls that define a receiving area for the vehicle. Once the vehicle is located in the receiving area, a coolant or extinguishing agent can be poured into the receiving area to extinguish the burning vehicle. The disadvantage of this is that the handling of the container transporter with the container, vehicle, and coolant or extinguishing agent is significantly impaired. To avoid this, the extinguishing agent could be filled only to a small height or completely drained during the journey. This could lead to a flare-up during transport, as neither oxygen isolation nor cooling is provided.

[0015] DE 10 2022 112 506 A1 discloses an extinguishing system for parked vehicles. It features an erectable wall arrangement that can be placed around the vehicle when needed. The vehicle is thus enclosed in a temporarily erectable container, which is then filled with an extinguishing agent to extinguish the fire on the vehicle.

[0016] WO 2021 / 168071 A1 discloses a remotely controllable powder extinguishing system. A powder extinguishing agent is stored in a container, which is transported via a pipe system to a remotely controllable unit, from where the powder extinguishing agent can then be distributed in the fire area.

[0017] From CN 206483014 U a battery storage system is known in which a burning battery is extinguished by filling the storage area with sand.

[0018] JP 2014-158508 A discloses a fire extinguishing system for batteries in which a fire extinguishing powder is introduced into the area of a burning battery as extinguishing sand.

[0019] It is therefore an object of the present invention to provide an improved method and an improved device for extinguishing a fire on an object, in particular on an electrical object, which in particular permanently extinguishes a fire on a lithium-ion battery in a simple and safe manner.

[0020] The object is achieved according to the invention with the method according to claim 1 and the device according to claim 8. Advantageous embodiments of the invention can then be found in the corresponding subclaims.

[0021] According to claim 1, a method for extinguishing a fire on an object is proposed, the method comprising the following steps: - Providing a container containing a solid granulate of loose solid particles, - creating a fluidized bed within the container filled with the solid granules by introducing a gaseous fluid into the solid granules in such a way that the burning object sinks at least partially into the fluidized bed, - wherein the object is introduced into the container before or after the creation of the fluidized bed, and - stopping the introduction of the gaseous fluid into the container when the burning object has sunk at least partially into the fluidized bed in order to stop the creation of the fluidized bed and to embed the sunken object at least partially in the solid granules.

[0022] According to the invention, it is proposed that in a container containing a solid granulate of loose solid particles, a fluidized bed is created by introducing or blowing a gaseous fluid into which the burning object sinks at least partially, preferably completely. Once the object has sunk at least partially into this fluidized bed, the introduction of the gaseous fluid is stopped, causing the fluidized bed of solid granulate with its solid particles to collapse and embed the burning object in the solid granulate. This deprives the fire of the necessary oxygen, reducing the risk of reignition.

[0023] A fluidized bed is a physical phenomenon that occurs when a solid particulate matter (usually in a container) is exposed to the right conditions for it to behave like a fluid. The resulting fluidized bed medium has, in the broadest sense, properties and characteristics of a normal fluid, such as the ability to flow freely under gravity. Depending on the prevailing conditions, it is sometimes observed that light objects float on this fluidized bed while heavy objects sink.

[0024] By creating a fluidized bed in a container, a burning object can be quickly buried beneath the solid granules. The fluid flow rate and the arrangement of the gas outlets should be selected so that objects sink as quickly as possible. Once the object has sunk into the fluidized bed, the fluid supply is shut off, and the solid granules return to solid.

[0025] The burning object can be introduced into the fluidized bed, for example, using a crane (for large objects such as cars) or tongs. However, the object can also be placed in a non-burning state on the surface formed by the solid granules, with the fluidized bed only being created when the object begins to burn. This allows for the establishment of a type of emergency system for the optimal extinguishing of highly flammable or rapidly combustible objects.

[0026] The object may be an electronic device that contains, in particular, a battery, for example a lithium-ion battery.

[0027] According to one embodiment, the solid granulate is sand. However, other materials used to extinguish fires are also conceivable.

[0028] According to one embodiment, the gaseous fluid is air or an inert gas or a gaseous fluid containing at least 50% CO2, preferably at least 70% CO2, particularly preferably at least 90% CO2.

[0029] The gaseous fluid can be selected in such a way that it contains no oxygen or only a very low oxygen content (less than one percent). This allows the fire to be extinguished in the broadest sense beneath the solid granules.

[0030] According to one embodiment, after the generation of the fluidized bed has been terminated by terminating the introduction of the gaseous fluid, a liquid extinguishing agent is introduced into the solid granulate embedding the sunken object.

[0031] By introducing an extinguishing agent, such as water, the solid granulate, especially the bottom layer, can now be additionally watered. This provides additional cooling, which is particularly beneficial in the case of lithium-ion battery fires and simultaneously promotes rapid flame extinguishing.

[0032] According to one embodiment, it is provided that at least after the generation of the fluidized bed has ended by stopping the introduction of the gaseous fluid, the container and / or the solid granulate embedding the sunken object is cooled by a coolant and / or a cooling device.

[0033] Particularly when using an object in which a lithium-ion battery has ignited, it is advantageous for the container and / or the solid granules to be actively cooled in order to interrupt the chain reaction described above when such battery cells catch fire. Cooling by means of the cooling device is particularly achieved by actively removing heat from the container interior, which contains the solid granules and the burning object.

[0034] According to one embodiment, it is provided that the non-burning object is provided on the solid granulate in the container, wherein a fire on the object is detected by means of a detection device and, after the detection of the fire, the generation and termination of the fluidized bed is triggered.

[0035] The process is only initiated once a fire has actually been detected on the object. The object rests on the surface of the solid granules in a non-burning state. If a fire is detected, the gaseous fluid is injected, creating a fluidized bed, and the object sinks into the fluidized bed.

[0036] Subsequently, the injection of the gaseous fluid is stopped, causing the fluidized bed to collapse and the solid granules to solidify again. The object that has caught fire is thus automatically embedded in the solid granules, and the fire is extinguished. Upon detection of the fire, the extinguishing method according to the invention is implemented by first creating the fluidized bed by introducing the gaseous fluid. After the object that has caught fire has sunk into the solid granules, the injection of the gaseous fluid is stopped.

[0037] It can be advantageous if, when a fire outbreak is detected, a charging process that charges a lithium-ion battery of the object is terminated.

[0038] The object is also achieved with the device according to claim 8 for extinguishing a fire on an object, with - a container filled with a solid granulate of loose solid particles, - a fluid introduction device designed to introduce a gaseous fluid into the solid granules to create a fluidized bed within the container filled with the solid granules, and - a control device which is configured to generate a switch-on signal for the fluid introduction device in order to start the generation of the fluidized bed when the burning object has been or is being introduced into the container, and to generate a switch-off signal for the fluid introduction device in order to end the generation of the fluidized bed when the burning object has sunk at least partially into the fluidized bed in order to embed the burning object at least partially in the solid granulate.

[0039] The device is configured to carry out the method described above.

[0040] According to one embodiment, the container has an air-permeable bottom which is provided at the bottom of the container and cooperates with the fluid introduction device in such a way that the gaseous fluid is introduced through the air-permeable bottom into the solid granulate to create the fluidized bed.

[0041] Such an air-permeable floor can be realized, for example, using an air-permeable membrane.

[0042] According to one embodiment, the device has a detection device which is configured to detect a fire on the object located in the container, wherein the control device is configured to generate the switch-on signal in dependence on the detection of the fire.

[0043] It can be provided that the control device is further configured to interrupt a loading process of the object located in the container depending on the detection of the fire.

[0044] For example, the device can be a charging device for accumulators, which can be used to charge small, mobile objects such as smartphones, laptops, and the like, or a device for charging large objects such as electric vehicles. The object to be charged, which contains a battery (accumulator) that may contain one or more cells, is placed on the surface of the solidified solid granulate. The object is then connected to a charging device of the charging device so that the battery can be charged with electrical energy.

[0045] If the detection device detects the outbreak of fire on the object, the control device recognizes the fire and generates an activation signal, causing the gaseous fluid to be injected into the container and thus into the solid granules. This creates a fluidized bed into which the ignited object sinks. After a certain time has elapsed, or upon detection of sufficient sinking into the fluidized bed, the control device generates the deactivation signal, interrupting the injection of the gaseous fluid and causing the fluidized bed to collapse. The burning object is thus embedded in the now solidifying solid granules.

[0046] Such a charging device therefore additionally has a charging device in order to be able to charge the object within the extinguishing device.

[0047] According to one embodiment, it is provided that the extinguishing agent filling device has been configured to fill an extinguishing agent into the container, wherein the control device is further configured to start filling the extinguishing agent into the container after the switch-off signal for the fluid introduction device has been generated.

[0048] According to one embodiment, it is provided that the device comprises a cooling device which is designed to cool the container and / or the solid granulate.

[0049] The invention is explained in more detail by way of example with reference to the accompanying figures. They show: Fig. 1 schematic representation of the extinguishing process on a burning object, Fig. 2 schematic representation of the extinguishing process on an electric car.

[0050] Fig. 1 shows in a schematically simplified representation the extinguishing process by means of the extinguishing device 10 in the 3 essential process steps a) to c).

[0051] First, a container 11 containing solid granules 12 is provided, the container having an air-permeable bottom 13. This divides the interior of the container 11 into a working chamber 14 and a blower chamber 15. The blower chamber 15 is located below the air-permeable bottom 13 and is operatively connected to a blower 16, which can inject a gaseous fluid into the blower chamber 15. The working chamber 14 contains the solid granules 12.

[0052] If, as shown in the first process step a), a gaseous fluid is blown into the blower chamber 15 below the air-permeable floor 13 by the blower 16, the gaseous fluid is blown through the air-permeable floor 13 into the working chamber 14 of the container 11. This forms a fluidized bed 17 (also called a fluidized bed), which has the physical properties of a liquid.

[0053] The air-permeable base 13 can be, for example, an air-permeable membrane or a perforated plate. The openings should be smaller than the average diameter of the solid particles of the solid granulate 12.

[0054] The blower 16 can be designed to suck in the ambient air and introduce it into the blower chamber 15. However, it is also conceivable that special gases, such as CO2 or an inert gas, are blown in or injected.

[0055] The combustible object 20 now sinks, as shown in the second process step b), into the formed fluidized bed 17 and sinks down to the air-permeable floor 13. Already in this process step, it can happen that the fire that has broken out on the object 20 is extinguished.

[0056] After the object 20 has sunk into the container onto the bottom 13, the blower 16 is switched off, as shown in the third process step c), whereby no further gas is injected into the blower chamber 15. The previously formed fluidized bed 17 now collapses, embedding the object 20 in the solidifying solid granulate 12.

[0057] For the purposes of the present invention, the term "solidifying" solid granules means that the solid granules assume the state they had before the fluidized bed was created. Solidifying here means a firmer consistency than the fluidized bed.

[0058] The fan 16 is controlled by a control device 18, which generates corresponding on and off signals. A sensor 19 can be provided to detect the outbreak of a fire. If the sensor 19 detects the outbreak of a fire, a corresponding on signal is generated by the control device 18, and the fan 16 is switched on, creating the fluidized bed 17 and causing the burning object 20 to sink into it. This allows an ignited object to be extinguished automatically.

[0059] Fig.Figure 2 shows an application for extinguishing and transporting an electric vehicle. The burning electric vehicle 30 is placed into the fluidized bed 17 created in the container 11 using a crane 31. The electric vehicle 30 then sinks into the container on the floor. The fluidized bed 17 collapses when the fan is switched off, embedding the electric vehicle in the solid granules (process step c)).

[0060] To support this, at least the lower layer in the area of the blower chamber 15 and above the air-permeable floor 13 is then flooded with an extinguishing agent 32 to achieve active cooling. This not only cools the vehicle 30, but also the solid granulate, which has a particularly positive effect on firefighting in the electric vehicle 30.

[0061] Thanks to the solidified solid granulate, transport without sloshing loads is now possible. List of reference symbols 10 Device 11 containers 12 solid granules 13 breathable floor 14 Workspace 15 Blower room 16 blowers 17 Fluidized bed 18 Control device 19 Sensor 20 flammable object 30 electric vehicles 31 crane 32 extinguishing agents

Claims

[1] A method for extinguishing a fire on an object (20, 30), the method comprising the following steps: - providing a container (11) containing a solid granulate (12) of loose solid particles, - creating a fluidized bed (17) within the container (11) filled with the solid granulate (12) by introducing a gaseous fluid into the solid granulate (12) in such a way that the burning object (20, 30) sinks at least partially into the fluidized bed (17), - wherein the object (20, 30) is introduced into the container (11) before or after the creation of the fluidized bed (17), and - stopping the introduction of the gaseous fluid into the container (11) when the burning object (20, 30) has sunk at least partially into the fluidized bed (17) in order to stop the generation of the fluidized bed (17) and to embed the sunken object (20, 30) at least partially in the solid granulate (12). [2] Method according to claim 1, characterized by that the solid granulate (12) is sand. [3] Method according to claim 1 or 2, characterized by that the gaseous fluid is air or an inert gas or a gaseous fluid which contains at least 50% CO2, preferably at least 70% CO2, particularly preferably at least 90% CO2. [4] Method according to one of the preceding claims, characterized bythat after the generation of the fluidized bed (17) has ended by stopping the introduction of the gaseous fluid, a liquid extinguishing agent (32) is introduced into the solid granulate (12) embedding the sunken object (20, 30). [5] Method according to one of the preceding claims, characterized by that at least after the generation of the fluidized bed (17) has ended by stopping the introduction of the gaseous fluid, the container (11) and / or the solid granulate (12) embedding the sunken object (20, 30) is cooled by a coolant and / or a cooling device. [6] Method according to one of the preceding claims, characterized bythat the non-burning object (20, 30) is provided on the solid granulate (12) in the container (11), wherein a fire on the object (20, 30) is detected by means of a detection device (19) and the generation and termination of the fluidized bed (17) is triggered after the detection of the fire. [7] Method according to one of the preceding claims, characterized by that the article (20) contains a rechargeable battery, in particular a lithium-ion battery. [8] Device (10) for extinguishing a fire on an object (20, 30) with - a container (11) filled with a solid granulate (12) of loose solid particles, - a fluid introduction device which is arranged to introduce a gaseous fluid into the solid granulate (12) to create a fluidized bed (17) within the container (11) filled with the solid granulate (12), and - a control device (18) which is designed to generate a switch-on signal for the fluid introduction device in order to start the generation of the fluidized bed (17) when the burning object (20, 30) has been or is being introduced into the container (11), and to generate a switch-off signal for the fluid introduction device in order to end the generation of the fluidized bed (17) when the burning object (20, 30) has sunk at least partially into the fluidized bed (17) in order to embed the burning object (20, 30) at least partially in the solid granulate (12). [9] Device (10) according to claim 8, characterized bythat the container (11) has an air-permeable bottom (13) which is provided at the base of the container (11) and cooperates with the fluid introduction device in such a way that the gaseous fluid is introduced through the air-permeable bottom (13) into the solid granulate (12) to produce the fluidized bed (17). [10] Device (10) according to claim 8 or 9, characterized by that the device (10) has a detection device (19) which is arranged to detect a fire on the object (20, 30) located in the container (11), wherein the control device (18) is arranged to generate the switch-on signal in dependence on the detection of the fire. [11] Device (10) according to claim 10, characterized by that the control device (18) is further configured to interrupt a loading process of the object (20, 30) located in the container (11) as a function of the detection of the fire. [12] Device (10) according to one of claims 8 to 11, characterized by that the device (10) has an extinguishing agent filling device which is designed to fill an extinguishing agent (32) into the container (11), wherein the control device (18) is further designed to start filling the extinguishing agent (32) into the container (11) after the switch-off signal for the fluid introduction device has been generated. [13] Device (10) according to one of claims 8 to 12, characterized by that the device (10) comprises a cooling device which is designed to cool the container (11) and / or the solid granulate (12).

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