A cable pipe gallery liquid nitrogen fire extinguishing efficiency test experimental device

Abstract

The utility model discloses a cable pipe gallery liquid nitrogen fire extinguishing efficiency test experimental device, the device includes the combustion chamber and is located the liquid nitrogen fire extinguishing agent bottle outside the combustion chamber, the top of combustion chamber is equipped with the adjustable fire -extinguishing spray head of injection angle, the fire -extinguishing spray head is connected with the liquid nitrogen fire extinguishing agent bottle through the conveying pipeline, is equipped with pressure regulating valve and pressure gauge on the conveying pipeline, be equipped with the adjustable cable fixing frame for simulating different cable laying mode in the combustion chamber, the below of cable fixing frame is equipped with the ignition assembly for igniting cable, the lateral wall of combustion chamber is equipped with pressure -relief component, and the top is installed with the smoke detector and temperature sensor. The utility model aims at improving cable pipe gallery liquid nitrogen fire extinguishing simulation reality.

Description

Technical Field

[0001] This utility model relates to the field of fire protection engineering technology, and in particular to an experimental device for testing the fire extinguishing effectiveness of liquid nitrogen in cable tunnels. Background Technology

[0002] Cable tunnels, serving as the "lifeline" of urban power transmission, typically house a dense network of high-voltage cables. Due to factors such as cable insulation aging, partial discharge, and external damage, the risk of fire within these tunnels is high. Cable fires are characterized by long smoldering times, high heat generation, rapid spread of fire along cable bundles, and the production of large amounts of toxic smoke. Furthermore, the confined space and complex environment of cable tunnels make firefighting extremely difficult, potentially leading to significant economic losses and social impact. Therefore, to better study the fire suppression effectiveness within cable tunnels, simulating the layout characteristics of multiple cable installations within the tunnel can provide multi-dimensional data support for evaluating actual fire suppression performance.

[0003] Liquid nitrogen, as a fire extinguishing medium, provides a faster and more thorough fire suppression effect. As a fire extinguishing system for cable tunnels, it is characterized by being pollution-free, non-conductive, and leaving no residue after extinguishing. The fire extinguishing efficiency of liquid nitrogen in cable tunnels is significantly affected by factors such as spray pressure, the relative position of the nozzle and the fire source, and the cable laying method. Existing fire extinguishing efficiency testing devices are mostly designed for general electrical fires. For example, the utility model application CN113101581A discloses a city integrated pipe tunnel fire simulation system and testing method. This system achieves precise fire extinguishing by directly placing automatic fire extinguishing devices in high-risk areas of cable fires, avoiding the resource waste of total flooding fire extinguishing. The fire extinguishing control system integrates multiple sensors such as thermocouples, linear heat detectors, and image fire detectors. It uses a data acquisition unit and a microcontroller to achieve real-time analysis and linkage control of fire signals, supporting early fire identification and rapid response. However, it relies on manual judgment for activation, resulting in a response delay. Constructing a near-fire scenario using a burning oil pan and non-flame-retardant cables cannot reproduce the fire characteristics caused by actual factors such as cable insulation aging and short circuits. There is a lack of specialized equipment that fits the actual situation of cable tunnels. Utility Model Content

[0004] The main purpose of this invention is to provide a test device for testing the effectiveness of liquid nitrogen fire extinguishing in cable tunnels, aiming to solve the problem that existing fire extinguishing systems for cable tunnels cannot effectively adapt to the actual scenarios of cable tunnels.

[0005] To achieve the above objectives, this utility model provides an experimental device for testing the fire extinguishing effectiveness of liquid nitrogen in cable tunnels. The device includes a combustion chamber and a liquid nitrogen extinguishing agent bottle located outside the combustion chamber.

[0006] The top of the combustion chamber is equipped with an adjustable spray angle fire extinguishing nozzle, which is connected to a liquid nitrogen fire extinguishing agent cylinder via a delivery pipeline. The delivery pipeline is equipped with a pressure regulating valve and a pressure gauge.

[0007] The combustion chamber is equipped with an adjustable cable holder for simulating different cable laying methods, and an ignition assembly for igniting the cable is located below the cable holder.

[0008] The combustion chamber is equipped with a pressure relief assembly on its side wall and a smoke detector and a temperature detector are installed on its top.

[0009] Optionally, the cable fixing frame includes a vertical support and multiple support platforms arranged along the height direction, the positions of the support platforms being adjustable; the height of the cable fixing frame is 2.2-2.6m, and the support platforms are evenly distributed in the vertical direction.

[0010] Optionally, the fire extinguishing nozzle is connected to the delivery pipeline via a universal joint, and the nozzle angle adjustment range is 0-360 degrees.

[0011] Optionally, the combustion chamber is provided with a thermocouple tree, which includes a support and a plurality of armored thermocouples mounted on the support from top to bottom.

[0012] Optionally, the measuring end of the armored thermocouple is provided with a fixing clip for fixing the thermocouple to the surface of the cable.

[0013] Optionally, a gas collection probe is provided in the combustion chamber, and the gas collection probe is connected to a gas component analyzer located outside the combustion chamber via a gas collection pipe.

[0014] Optionally, a filter screen with a pore size of 0.5 mm is installed at the front end of the gas collection probe.

[0015] Optionally, the pressure relief assembly includes a pressure relief valve and a buffer chamber.

[0016] Optionally, the combustion chamber is provided with a transparent cover, and a high-definition camera is installed inside the transparent cover.

[0017] Optionally, the conveying pipeline is covered with an insulation layer with a thickness of 20-30mm.

[0018] Beneficial effects:

[0019] (1) The adjustable fixing frame enables accurate simulation of typical cable layout in the pipe gallery, overcomes the problem of disconnect between traditional devices and actual scenarios, realizes multi-scenario reproduction, and allows independent adjustment of multiple parameters such as injection pressure, angle, and distance to meet the needs of systematic experiments and improve the simulation realism.

[0020] (2) Obtain cable surface temperature distribution data through thermocouple tree to realize temperature field monitoring: monitor the changes in key gas concentrations in real time during fire extinguishing and analyze gas evolution: visually record the entire fire extinguishing process to make up for the shortcomings of pure data monitoring; and realize the temporal correlation analysis of temperature, gas and image data to achieve multi-parameter synchronization and ultimately achieve comprehensive data acquisition.

[0021] (3) Experimental data can be directly used to guide key parameters such as nozzle arrangement and pressure setting of pipe gallery fire extinguishing system; through multi-condition testing, a database of the correspondence between spray parameters and fire extinguishing effect is established to quantify the fire extinguishing law; and to provide technical support for the promotion and application of liquid nitrogen fire extinguishing system in complex pipe gallery environment.

[0022] (4) The pressure relief components and the exhaust gas treatment unit constitute a complete safety system and realize multiple protection designs; the anti-clogging probe and high temperature resistant design ensure that the device can be reused and is conducive to long-term stable operation. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of an embodiment of the experimental device for testing the effectiveness of liquid nitrogen fire extinguishing in cable tunnels according to this utility model;

[0025] Figure 2 for Figure 1 Enlarged view of an embodiment of single-sided cable laying;

[0026] Figure 3 for Figure 1 Enlarged view of an embodiment of overhead cable laying in China;

[0027] Figure 4 for Figure 1 A detailed structural diagram of the cable holder.

[0028] Explanation of icon numbers:

[0029] 101. Combustion chamber; 102. Ignition assembly; 103. Cable holder; 104. Transparent cover; 105. Smoke detector; 106. Temperature detector; 107. Pressure relief assembly;

[0030] 201. Liquid nitrogen extinguishing agent cylinder; 202. Pressure regulating valve; 203. Pressure gauge; 204. Delivery pipeline; 205. Fire extinguishing nozzle;

[0031] 301. Gas composition analyzer; 302. Dryer; 303. Gas collection probe; 304. Waste gas treatment unit;

[0032] 401. Thermocouple tree; 402. Temperature acquisition instrument; 403. Armored thermocouple.

[0033] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0035] See Figure 1 This utility model provides a schematic diagram of an embodiment of a test device for testing the extinguishing effectiveness of liquid nitrogen in cable tunnels. The device includes a combustion chamber 101 and a liquid nitrogen extinguishing agent bottle 201 located outside the combustion chamber 101. The combustion chamber 101 has an adjustable-angle extinguishing nozzle 205 at its top, which is connected to the liquid nitrogen extinguishing agent bottle 201 via a delivery pipe 204. The delivery pipe 204 is equipped with a pressure regulating valve 202 and a pressure gauge 203. The combustion chamber 101 also has an adjustable cable fixing frame 103 for simulating different cable laying methods. Below the cable fixing frame 103 is an ignition assembly 102 for igniting the cable. The sidewall of the combustion chamber 101 also has a pressure relief assembly 107, and a smoke detector 105 and a heat detector 106 are installed at its top.

[0036] Furthermore, the pressure regulating valve 202 can flexibly adjust the injection pressure of the liquid nitrogen extinguishing agent and display it through the pressure gauge 203, thereby effectively controlling the pressure of the extinguishing nozzle 205.

[0037] Furthermore, the fire extinguishing nozzle 205 is connected to the delivery pipe 204 via a universal joint. The angle adjustment range of the fire extinguishing nozzle 205 is 0-360 degrees (preferably 0-180 degrees, with the nozzle pointing to the left horizontally at the top of the tunnel, which is 0 degrees). By adjusting the nozzle angle, the relative position with the fire source can be matched. Preferably, the spray pressure is controlled at 15-20 MPa, the spray angle at 45-90 degrees, and the spray distance at 2-5 m to form a uniform coverage of a square or rectangular space, thereby enabling the testing of the fire extinguishing efficiency of the extinguishing agent for cable tunnel fires.

[0038] Furthermore, the ignition assembly 102 is an adjustable power electric heating device or a gas flame generator, capable of simulating cable fire scenarios of varying intensities.

[0039] Furthermore, the cable fixing bracket 103 includes a vertical support and multiple support platforms arranged along the height direction. Preferably, the support platforms are fixed to the slide rail by screws and diagonal rods, as shown in the specific structure. Figure 4 As shown, the height of the support platform can be adjusted by changing the relative positions of the screws and the diagonal rods. Different combinations of platform heights allow for adjustment of the cable laying spacing and height. The cable layout simulation includes typical layout methods such as single-sided laying, layered laying, and overhead laying. Figure 2-3 As shown, where Figure 2 It is laid on one side only. Figure 3 It is laid overhead.

[0040] The height of the cable fixing bracket 103 is 2.2-2.6m (preferably 2.4m), and preferably, the support platform is evenly distributed in the vertical direction.

[0041] Furthermore, the combustion chamber 101 is provided with a thermocouple tree 401, which includes a support and a plurality of armored thermocouples 403 mounted on the support from top to bottom. Preferably, the measuring ends of the armored thermocouples 403 are provided with fixing clips for bringing the measuring ends of the thermocouples 403 close to the surface of the cable insulation layer and adjusting the spacing between the thermocouples 403 to be consistent with the cable spacing.

[0042] The armored thermocouple 403 is connected to the temperature acquisition instrument 402, which is located outside the combustion chamber 101. The temperature acquisition instrument 402 transmits data via the RS485 communication protocol, with a transmission baud rate of 9600bps and even parity to ensure real-time temperature data transmission. The platform includes a built-in data storage module (supporting Excel and CSV format export) and a curve analysis module (capable of generating temperature-time curves).

[0043] Furthermore, a gas collection probe 303 is provided inside the combustion chamber 101. The gas collection probe 303 is connected to a gas component analyzer 301 located outside the combustion chamber 101 via a gas collection pipe, preferably a PVC flexible tube. Preferably, the gas collection probe 303 is placed at a gas component measurement point inside the combustion chamber 101 and connected to the external gas component analyzer 301 via a high-temperature resistant PVC flexible tube and a dryer 302. This allows for real-time recording of gas component changes within the combustion chamber 101 during combustion, specifically monitoring changes in O2, CO2, and other concentrations to assess the fire extinguishing and asphyxiation effect. The dryer 301 ensures the accuracy of the gas samples.

[0044] The gas composition analyzer 301 is also connected to the waste gas treatment unit 304. Preferably, the waste gas treatment unit 304 is connected to the outlet of the gas composition analyzer 301 via a pipeline. The waste gas treatment unit 304 contains, in sequence, an activated carbon adsorption layer and a molecular sieve drying layer. The activated carbon filling amount is not less than 1.5 kg, and the molecular sieve is of type 13X. The activated carbon adsorbs toxic gases, and the molecular sieve provides deep purification, meeting environmental protection requirements and achieving green experimentation.

[0045] Furthermore, the gas collection probe 303 adopts an anti-clogging design, including a stainless steel probe housing, a high-temperature resistant filter, and a self-cleaning component. The surface of the housing is treated with a polytetrafluoroethylene coating. The self-cleaning component includes a miniature air pump and an air nozzle, and the air pump is connected to the delivery pipe 204 through a branch pipe. Preferably, it automatically sprays air every 5 minutes to remove ash accumulation on the filter surface. More preferably, the filter has a pore size of 0.5 mm. The anti-clogging design of the gas collection probe 303 ensures the reliability of long-term experiments.

[0046] Furthermore, the pressure relief assembly 107 includes a pressure relief valve and a buffer chamber. The pressure relief valve is set to open at a pressure of 0.12 MPa. It automatically opens when the pressure inside the combustion chamber 101 exceeds the threshold, and the airflow is discharged after being mitigated by the buffer chamber, thus ensuring experimental safety.

[0047] Furthermore, a transparent cover 104 is provided inside the combustion chamber 101, and a high-definition camera is installed inside the transparent cover 104. The process of flame morphology change is recorded through the transparent cover 104, visually presenting the diffusion law of the extinguishing agent and the fire suppression process.

[0048] Furthermore, the conveying pipe 204 is covered with an insulation layer. Preferably, the conveying pipe 204 is made of heat-insulating material, and an insulation layer is provided on the outer surface of the pipe to prevent liquid nitrogen from vaporizing during the conveying process. More preferably, the thickness of the insulation layer is 20-30 mm.

[0049] Furthermore, to better illustrate the specific setup of the above-mentioned experimental apparatus for testing the effectiveness of liquid nitrogen fire extinguishing in cable tunnels, the specific test steps are disclosed below:

[0050] Step 1: Before use, check the pressure relief device 107 and the airtightness of the device. Then, according to the experimental requirements, adjust the distance between the fire extinguishing nozzle 205 and the cable fixing frame 103 to the set distance. Place the gas collection probe 303 at the measurement point and connect it to the dryer 302 and then the gas component analyzer 301. Install the thermocouple into the thermocouple tree 401 and connect it to the temperature acquisition instrument. Place the armored thermocouple 403 close to the surface of the cable insulation layer. Place a high-definition camera inside the transparent cover 104 and adjust the spray pressure through the pressure regulating valve 202.

[0051] Step 2: Arrange cables on the adjustable cable holder 103 and adjust the cable laying method;

[0052] Step 3: Ignite the cable using the ignition assembly 102 to simulate a cable fire;

[0053] Step 4: Adjust the spray angle and spray pressure of the fire extinguishing nozzle 205, open the liquid nitrogen fire extinguishing agent bottle 201, and deliver nitrogen gas to the fire extinguishing nozzle 205 at the top of the combustion chamber 101 at the pressure designed under different working conditions, so that the spray diffuses and fills the combustion chamber 101 to extinguish the fire.

[0054] Step 5: Simultaneously activate the thermocouple tree 401, gas collection probe 303, and high-definition camera to collect temperature data, gas concentration data, and image data in real time during the fire extinguishing process;

[0055] Step 6: After the flames are extinguished and cooled, open the combustion chamber 101 and clean it. Replace the cable and conduct the next set of experiments. Under the same cable laying method, adjust the spray pressure, spray distance, spray angle, etc., and repeat the above experiments to obtain fire extinguishing performance data. Change the cable laying method, repeat the experiment, and compare the fire extinguishing performance parameters under different scenarios.

[0056] Step 7: After the experiment, the collected data, including the fire extinguishing image data obtained from the high-definition camera, the temperature data from the temperature data acquisition instrument 402, and the pressure data from the pressure gauge 203, are analyzed to evaluate the fire extinguishing efficiency of the liquid nitrogen extinguishing agent under different parameters. The waste gas is then filtered, collected, and treated by the waste gas treatment unit 304.

[0057] In the above embodiments, by simulating a real cable tunnel scenario and adjusting multiple parameters, the extinguishing pattern of liquid nitrogen on cable fires can be accurately obtained. The experimental data can be directly used to guide the nozzle arrangement, pressure setting, and extinguishing time control of the liquid nitrogen extinguishing system for cable tunnels, solving the problem of the disconnect between existing devices and actual cable tunnel scenarios.

[0058] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the inventive concept of this utility model and the contents of this utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

Claims

1. An experimental device for testing the fire extinguishing effectiveness of liquid nitrogen in cable tunnels, characterized in that, The device includes a combustion chamber (101) and a liquid nitrogen extinguishing agent bottle (201) located outside the combustion chamber (101). The combustion chamber (101) is equipped with an adjustable spray angle fire extinguishing nozzle (205) at the top. The fire extinguishing nozzle (205) is connected to the liquid nitrogen fire extinguishing agent bottle (201) through a delivery pipe (204). The delivery pipe (204) is equipped with a pressure regulating valve (202) and a pressure gauge (203). The combustion chamber (101) is equipped with an adjustable cable holder (103) for simulating different cable laying methods, and an ignition assembly (102) for igniting the cable is provided below the cable holder (103). The combustion chamber (101) is provided with a pressure relief assembly (107) on its side wall and a smoke detector (105) and a heat detector (106) on its top.

2. The apparatus according to claim 1, characterized in that, The cable fixing frame (103) includes a vertical support and multiple support platforms arranged along the height direction, the position of which is adjustable; the height of the cable fixing frame (103) is 2.2-2.6m, and the support platforms are evenly distributed in the vertical direction.

3. The apparatus according to claim 1, characterized in that, The fire extinguishing nozzle (205) is connected to the delivery pipe (204) via a universal joint, and the nozzle angle adjustment range is 0-90 degrees.

4. The apparatus according to claim 1, characterized in that, The combustion chamber (101) is provided with a thermocouple tree (401), which includes a support and several armored thermocouples (403) installed on the support from top to bottom.

5. The apparatus according to claim 4, characterized in that, The measuring end of the armored thermocouple (403) is provided with a fixing clip for fixing the thermocouple to the surface of the cable.

6. The apparatus according to claim 1, characterized in that, The combustion chamber (101) is equipped with a gas collection probe (303), which is connected to a gas component analyzer (301) located outside the combustion chamber (101) via a gas collection pipe.

7. The apparatus according to claim 6, characterized in that, The gas collection probe (303) is equipped with a filter screen at its front end, and the filter screen has a pore size of 0.5 mm.

8. The apparatus according to claim 1, characterized in that, The pressure relief assembly (107) includes a pressure relief valve and a buffer chamber.

9. The apparatus according to claim 1, characterized in that, The combustion chamber (101) is equipped with a transparent cover (104), and a high-definition camera is installed inside the transparent cover (104).

10. The apparatus according to any one of claims 1 to 9, characterized in that, The conveying pipeline (204) is covered with an insulation layer with a thickness of 20-30mm.

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