An experimental device and method for testing the fire extinguishing concentration of lithium batteries

Abstract

The present invention relates to an experimental device for testing the fire extinguishing concentration of lithium batteries, including a high-pressure vessel; the high-pressure vessel is externally connected with an induction terminal, a vacuum pump, a vacuum gauge, a gas fire extinguishing agent injection port, a liquid fire extinguishing agent injection port, an air inlet, and a pressure sensor; an ignition electrode is arranged inside the high-pressure vessel; the induction terminal is used for externally connecting a power source and for connecting the internal lithium battery or a heater for heating the lithium battery; the vacuum pump is used for evacuating the high-pressure vessel. Through this experimental device, the present invention can conduct experiments on the fire extinguishing concentration of specific lithium batteries and specific fire extinguishing agents; finally, the correlation between the states of charging and deflagration of specific lithium batteries and deflagration of lithium batteries in the presence of an open flame and the required fire extinguishing concentration of specific fire extinguishing agents is verified and evaluated, which is helpful for the research and prevention of lithium battery fires.

Description

Technical Field

[0001] The present invention relates to a method for testing and evaluating the fire extinguishing concentration. Specifically, it is an experimental device and method for testing the fire extinguishing concentration of lithium battery fires, belonging to the field of lithium battery fire safety. Background Art

[0002] Lithium batteries, with their advantages of being clean, efficient, and reusable, have now been widely used in new energy transportation tools and equipment such as electric vehicles, electric bicycles, mobile phones, laptop computers, and power banks. For example, in the field of electric vehicles, the demand for in-vehicle power lithium batteries in 2016 was approximately 20 million kWh, and it is expected to reach 50 million kWh by 2020. However, with the rapid development of industries such as electric vehicles, electric bicycles, and mobile phones, related fire accidents have occurred frequently. Through joint investigations by the public security fire department and relevant technical experts, it has been found that most of these fires occurred during charging and were related to the thermal runaway of lithium batteries.

[0003] Lithium battery fires have characteristics such as fast combustion speed, high combustion intensity, generation of a large amount of toxic and combustible smoke, and the risk of explosion, which pose great difficulties for the effective extinguishment of lithium battery fires.

[0004] The design of the fire extinguishing concentration is the basis for the effective extinguishment of fires. At present, the research on the fire extinguishing concentration of lithium battery fires at home and abroad is in a blank stage. In the actual fire protection system design scenarios of lithium battery sites, there is insufficient design of the fire extinguishing concentration, resulting in poor fire extinguishing effects or even ineffective fire extinguishment.

[0005] Carrying out tests and research on the fire extinguishing concentration of lithium battery fires and establishing test methods and devices for the fire extinguishing concentration of common fire extinguishing agents such as gaseous fire extinguishing agents and liquid fire extinguishing agents for lithium battery fires can lay a foundation for the design of fire protection systems in lithium battery application sites, ensure fire extinguishing efficiency, and reduce personnel and property losses. Summary of the Invention

[0006] The purpose of the present invention is to provide an experimental device and method for testing the fire extinguishing concentration of lithium battery fires. Through this experimental device, experiments on the fire extinguishing concentration of specific lithium batteries and specific fire extinguishing agents can be carried out, and finally the correlation between the states of specific lithium battery charging deflagration and lithium battery deflagration when encountering an open fire and the fire extinguishing concentration required by specific fire extinguishing agents can be obtained. This helps in the research and prevention of lithium battery fires.

[0007] The present invention adopts the following technical solutions:

[0008] An experimental device for testing the fire extinguishing concentration of lithium batteries, including a high-pressure vessel 1; the high-pressure vessel 1 is externally connected with an induction terminal 3, a vacuum pump 4, a vacuum gauge 5, a gas fire extinguishing agent injection port 6, a liquid fire extinguishing agent injection port 7, an air inlet 8, and a pressure sensor 9; an ignition electrode 10 is arranged inside the high-pressure vessel 1; the induction terminal 3 is used to externally connect a power supply, and is used to connect the internal lithium battery or a heater for heating the lithium battery; the vacuum pump 4 is used to evacuate the high-pressure vessel 1.

[0009] Preferably, an observation window 2 is further arranged on the high-pressure vessel 1.

[0010] Preferably, the observation window 2 is made of high-temperature resistant material.

[0011] Preferably, the ignition electrode 10 is externally connected with an igniter.

[0012] Preferably, the pressure sensor 9 is externally connected with a pressure detector.

[0013] Preferably, the high-pressure vessel 1 is processed from high-strength metal material, and the pressure resistance strength is at least 10 MPa.

[0014] Preferably, the working current range of the induction terminal is 0 - 100 A, which can meet the circuit requirements during the heating or overcharging of the lithium battery.

[0015] Preferably, the range of the vacuum gauge is -101.325 kPa - 0 kPa, and the accuracy is at least 0.1 kPa; the range of the pressure monitor is 0 kPa - 1000 kPa, and the accuracy is at least 1 kPa; the ignition voltage of the ignition electrode 10 is 10 kV - 15 kV.

[0016] A testing method for the above experimental device for testing the fire extinguishing concentration of lithium batteries, including the following steps:

[0017] S1. Place the lithium battery in the high-pressure vessel 1, and connect the power supply line of the electric heating plate or the overcharging circuit of the lithium battery with the induction terminal 3;

[0018] S2. Seal the high-pressure vessel 1, turn on the vacuum pump 4, evacuate until the vacuum degree of the vessel reaches the set value, stop the pump, observe the reading of the vacuum gauge, and the pressure rise within 5 minutes is not more than 50 Pa;

[0019] S3. Add the fire extinguishing agent through the gas fire extinguishing agent injection port 6 or the liquid fire extinguishing agent injection port 7 as appropriate, and monitor the concentration of the fire extinguishing agent through the reading of the vacuum gauge 5 based on the partial pressure method;

[0020] S4. After the concentration of the fire extinguishing agent reaches the preset value, open the air inlet 8 to make the pressure inside the high-pressure vessel 1 return to normal pressure;

[0021] S5. Turn on the heating or overcharging power supply until the lithium battery thermally runs away. If there is no open flame in the lithium battery, start the ignition electrode and continue to ignite at a frequency of 1 Hz.

[0022] S6, real-time monitoring of the value of the pressure sensor 9, if the explosion pressure in the high-pressure container is not greater than 20 kPa, then reduce the preset value of the fire extinguishing agent concentration, otherwise increase the preset value of the fire extinguishing agent concentration, and then repeat steps S1-S5;

[0023] S7. If the difference between the fire extinguishing agent concentrations greater than and not greater than 20 kPa in the high-pressure container is less than 0.1%, the experiment ends, and the fire extinguishing agent concentration with an explosion pressure not greater than 20 kPa is the fire extinguishing concentration for lithium battery fires.

[0024] In this solution, the fire extinguishing concentration is characterized by the negative pressure value after adding the fire extinguishing agent in a quasi-vacuum state reaching a set pressure value.

[0025] The beneficial effects of the present invention are:

[0026] 1) Through this experimental device, the fire extinguishing concentration experiment of specific lithium batteries and specific fire extinguishing agents can be carried out;

[0027] 2) Finally, the correlation between the state of specific lithium battery charging and deflagration, lithium battery deflagration when exposed to open flame, and the required extinguishing concentration of specific fire extinguishing agents was verified and evaluated. This is helpful for the research and prevention of lithium battery fires.

[0028] 3) The structure is simple, the implementation is convenient, and the functions are comprehensive; the induction terminal can be used to charge the lithium battery, and can also be used to heat the heating plate, thereby heating the lithium battery, and the design is ingenious. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of an experimental device for testing the fire extinguishing concentration of a lithium battery fire according to the present invention.

[0030] In the figure, 1. high pressure container, 2. observation window, 3. induction terminal, 4. vacuum pump, 5. vacuum gauge, 6. gas fire extinguishing agent inlet, 7. liquid fire extinguishing agent injection port, 8. air inlet, 9. pressure sensor, 10. ignition electrode. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] See also Figure 1, An experimental device for testing the fire extinguishing concentration of lithium batteries, including a high-pressure vessel 1; the high-pressure vessel 1 is externally connected to an induction terminal 3, a vacuum pump 4, a vacuum gauge 5, a gas fire extinguishing agent injection port 6, a liquid fire extinguishing agent injection port 7, an air inlet 8, and a pressure sensor 9; an ignition electrode 10 is provided inside the high-pressure vessel 1; the induction terminal 3 is used to externally connect a power supply and is used to connect the internal lithium battery or a heater for heating the lithium battery; the vacuum pump 4 is used to evacuate the high-pressure vessel 1.

[0033] In this embodiment, refer to Figure 1 , The high-pressure vessel 1 is further provided with an observation window 2.

[0034] In this embodiment, the observation window 2 is made of a high-temperature resistant material.

[0035] In this embodiment, refer to Figure 1 , The ignition electrode 10 is externally connected to an igniter, and the igniter is not shown in the drawings.

[0036] In this embodiment, refer to Figure 1 , The pressure sensor 9 is externally connected to a pressure detector. The pressure detector is not shown in the drawings.

[0037] In this embodiment, the high-pressure vessel 1 is processed from a high-strength metal material, and the pressure resistance is at least 10 MPa.

[0038] In this embodiment, the working current range of the induction terminal is 0 - 100 A, which can meet the circuit requirements during lithium battery heating or overcharging.

[0039] In this embodiment, refer to Figure 1 , The range of the vacuum gauge 5 is -101.325 kPa - 0 kPa, and the accuracy is at least 0.1 kPa; the range of the pressure monitor is 0 kPa - 1000 kPa, and the accuracy is at least 1 kPa; the ignition voltage of the ignition electrode 10 is 10 kV - 15 kV.

[0040] When the above experimental device for testing the fire extinguishing concentration of lithium batteries is specifically tested, it includes the following steps:

[0041] S1. Place the lithium battery in the high-pressure vessel 1, and connect the power cord of the electric heating plate or the overcharging circuit of the lithium battery to the induction terminal 3;

[0042] S2. Seal the high-pressure vessel 1, turn on the vacuum pump 4, evacuate until the vacuum degree of the vessel reaches the set value, stop the pump, observe the reading of the vacuum gauge, and the pressure rise within 5 minutes is not more than 50 Pa;

[0043] S3. Add the fire extinguishing agent through the gas fire extinguishing agent inlet 6 or the liquid fire extinguishing agent injection port 7 as appropriate, and monitor the concentration of the fire extinguishing agent by reading the vacuum gauge 5 based on the partial pressure method;

[0044] S4. After the concentration of the fire extinguishing agent reaches the preset value, open the air inlet 8 to restore normal pressure in the high-pressure container 1;

[0045] S5. Turn on the heating or overcharging power supply until the lithium battery experiences thermal runaway. If no open flame appears in the lithium battery, start the ignition electrode and continuously ignite at a frequency of 1 Hz;

[0046] S6. Monitor the value of the pressure sensor 9 in real time. If the explosion pressure in the high-pressure container is not greater than 20 kPa, reduce the preset value of the fire extinguishing agent concentration; otherwise, increase the preset value of the fire extinguishing agent concentration, and then repeat steps S1 - S5;

[0047] S7. If the difference in the fire extinguishing agent concentration when the explosion pressure in the high-pressure container is greater than and not greater than 20 kPa is less than 0.1%, the experiment ends, and the fire extinguishing agent concentration when the explosion pressure is not greater than 20 kPa is the fire extinguishing concentration for lithium battery fires.

[0048] It should be noted that the fire extinguishing concentration is characterized by the negative pressure value after adding the fire extinguishing agent in a quasi-vacuum state reaching the set pressure value. The vacuum pumping system consists of a vacuum pump, pipelines, and valves. When pumping vacuum, the vacuum degree is set to at least 667 Pa.

[0049] The above are the preferred embodiments of the present invention. Those of ordinary skill in the art can also make various transformations or improvements based on this. Without departing from the general concept of the present invention, these transformations or improvements should all fall within the scope of protection required by the present invention.

Claims

1. A test method for an experimental device for testing the fire extinguishing concentration of lithium batteries. It is characterized in that The experimental device comprises a high-pressure container (1); the high-pressure container (1) is externally connected with an induction terminal (3), a vacuum pump (4), a vacuum gauge (5), a gas fire extinguishing agent injection port (6), a liquid fire extinguishing agent injection port (7), an air inlet (8), and a pressure sensor (9); an ignition electrode (10) is arranged inside the high-pressure container (1); the induction terminal (3) is used for connecting an external power source and for connecting an internal lithium battery or a heater for heating the lithium battery; the vacuum pump (4) is used for evacuating the high-pressure container (1); The test method includes the following steps: S1. Place the lithium battery in a high-pressure container (1), and connect the power line of the electric heating plate or the lithium battery overcharge circuit to the induction terminal (3); S2, seal the high-pressure container (1), turn on the vacuum pump (4), pump until the vacuum degree of the container reaches the set value, stop the pump, observe the vacuum gauge reading, and the pressure rise is no more than 50 Pa within 5 minutes; S3, adding fire extinguishing agent through the gas fire extinguishing agent inlet (6) or the liquid fire extinguishing agent injection port (7) as appropriate, and monitoring the concentration of the fire extinguishing agent through the reading of the vacuum gauge (5) based on the partial pressure method; S4, after the concentration of the fire extinguishing agent reaches a preset value, the air inlet (8) is opened to restore the pressure in the high-pressure container (1) to normal pressure; S5. Turn on the heating or overcharging power supply until the lithium battery thermally runs away. If there is no open flame in the lithium battery, start the ignition electrode and continue to ignite at a frequency of 1 Hz. S6, real-time monitoring of the value of the pressure sensor (9), if the explosion pressure in the high-pressure container is not greater than 20 kPa, then the preset value of the fire extinguishing agent concentration is reduced, otherwise the preset value of the fire extinguishing agent concentration is increased, and then steps S1-S5 are repeated; S7. If the difference between the fire extinguishing agent concentrations greater than and not greater than 20 kPa in the high-pressure container is less than 0.1%, the experiment ends, and the fire extinguishing agent concentration with an explosion pressure not greater than 20 kPa is the fire extinguishing concentration for lithium battery fires.

2. The testing method of the experimental device for testing the fire extinguishing concentration of lithium battery fire as claimed in claim 1, Features: The high-pressure container (1) is also provided with an observation window (2).

3. The testing method of the experimental device for testing the fire extinguishing concentration of lithium battery fire as claimed in claim 2, Features: The observation window (2) is made of high temperature resistant material.

4. The testing method of the experimental device for testing the fire extinguishing concentration of lithium battery fire as claimed in claim 1, Features: The ignition electrode (10) is externally connected to an igniter.

5. The testing method of the experimental device for testing the fire extinguishing concentration of lithium battery fire as claimed in claim 1, Features: The pressure sensor (9) is externally connected to a pressure detector.

6. The testing method of the experimental device for testing the fire extinguishing concentration of lithium battery fire as claimed in claim 1, Features: The high-pressure container (1) is made of high-strength metal material and has a compressive strength of at least 10 MPa.

7. The testing method of the experimental device for testing the fire extinguishing concentration of lithium battery fire according to claim 1, Features: The operating current range of the induced terminal is 0 - 100A, which can meet the circuit requirements during the heating or overcharging of lithium batteries.

8. The test method of the experimental device for testing the fire extinguishing concentration of lithium batteries as described in claim 1, characterized in that: the measuring range of the vacuum gauge is -101.325 kPa - 0 kPa, and the accuracy is at least 0.1 kPa; the measuring range of the pressure monitor is 0 kPa - 1000 kPa, and the accuracy is at least 1 kPa; the ignition voltage of the ignition electrode (10) is 10 kV - 15 kV.

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