Combustible gas conveying pipeline fire explosion hazard experiment device and method

Abstract

The invention relates to a combustible gas conveying pipeline fire explosion hazard experiment device and method. The structure of the experimental device comprises a natural gas tank, a medium tank, a nitrogen tank, a pipeline, a leakage valve connected with the pipeline, a plurality of monitoring devices arranged around the leakage valve, a control terminal connected with the monitoring devices, a bleeder and a pressure gauge arranged on the pipeline, and a gas detector arranged on the bleeder, one end of the pipeline is respectively connected with the natural gas tank, the medium tank and the nitrogen tank. According to the invention, fire explosion scenes under the conditions of leakage ports of different sizes, different combustible cut-off mixing proportions and different shelters of the combustible gas conveying pipeline can be simulated, various actual possible conditions are comprehensively covered, and the risk of fire explosion of the combustible gas conveying pipeline is accurately evaluated.

Description

Technical Field

[0001] This invention relates to an experimental apparatus, specifically an experimental apparatus and method for testing the fire and explosion hazards of combustible gas transport pipelines. Background Technology

[0002] With the continuous growth of energy demand, combustible gases such as natural gas are playing an increasingly important role in energy supply. However, due to their high pressure, flammability, and explosiveness, leaks of these gases can easily lead to fires or explosions, posing a significant threat to human safety and the environment.

[0003] Currently, domestic fire and explosion testing platforms for natural gas pipelines and blended natural gas pipelines face numerous limitations in simulation experiments. These limitations include the inability to simulate the mixing of different flammable media, the inability to precisely control fire and explosion scenarios with varying leak sizes, the inability to accurately calculate the self-ignition probability of leaks in flammable gas pipelines, the inability to accurately assess the protective effectiveness of shielding materials, and the lack of comprehensive real-time measurements of thermal radiation and explosion overpressure. These issues mean that research on the impact range of pipeline leak fire and explosion accidents and the required protective measures relies primarily on empirical formulas and numerical simulations, making it difficult to truly reflect actual conditions. Summary of the Invention

[0004] The purpose of this invention is to provide an experimental device and method for fire and explosion hazards of combustible gas transportation pipelines, in order to solve the problems that existing experimental devices cannot simulate the mixing of different combustible media, cannot accurately control the size of the leak, cannot accurately calculate the self-ignition probability of the leak in the combustible gas transportation pipeline, and cannot accurately evaluate the protective effect of shielding materials.

[0005] The present invention is implemented as follows: a fire and explosion hazard test device for combustible gas transportation pipelines, the structure of which includes a natural gas tank, a medium tank, a nitrogen tank, a pipeline, a leakage valve connected to the pipeline, a number of monitoring devices arranged around the leakage valve, a control terminal connected to the monitoring devices, a vent pipe and a pressure gauge arranged on the pipeline, and a gas detector arranged on the vent pipe. One end of the pipeline is connected to the natural gas tank, the medium tank and the nitrogen tank respectively.

[0006] Furthermore, it also includes a mixer connected to the pipelines of the natural gas tank and the medium tank respectively, and the pipeline mixer is connected to the pipeline.

[0007] Furthermore, an igniter is installed above the leakage valve, and the igniter is connected to the control terminal.

[0008] Furthermore, the monitoring devices are arranged in a ring around the leak valve, with several rings of monitoring devices surrounding the leak valve.

[0009] Furthermore, the monitoring device includes a fixed rod and several sets of thermal radiation sensors and pressure sensors mounted on the fixed rod, and both the thermal radiation sensors and the pressure sensors are connected to the control terminal.

[0010] Furthermore, an obstruction is provided between the leakage valve and the detection device.

[0011] A method for testing the fire and explosion hazards of combustible gas transport pipelines includes the following steps: S1. Set up a fire and explosion hazard test device for any of the combustible gas conveying pipelines as described in any of claims 1-6; S2. Open the valve of the venting pipe, then open the valve of the nitrogen tank to inject nitrogen into the pipeline. When the oxygen content in the gas measured by the gas detector drops to the target oxygen content, close the valve of the nitrogen tank. S3. Inject combustible gas into the pipeline. After the nitrogen content in the gas measured by the gas detector drops to the target nitrogen content, close the valve of the vent pipe and continue to inject combustible gas into the pipeline. When the pressure value displayed on the pressure gauge reaches the target pressure, stop injecting combustible gas into the pipeline. S4. Start the control terminal, activate the software program related to the monitoring device, and begin real-time monitoring and recording of relevant data; S5. Open the leak valve to allow the combustible gas in the pipeline to leak out; S6. After the flame is extinguished, save the data of the monitoring device recorded by the control terminal; S7. Repeat steps S2-S6 to conduct tests under different diameters of the leakage valve and different pressure conditions of the pipeline. S8. The control terminal processes the collected data and calculates the fire protection effect of the obstruction and the probability of self-ignition due to frictional static electricity from pipeline leakage.

[0012] Furthermore, between step S5 and step S6, there is also an ignition step.

[0013] Furthermore, the formula for calculating the probability of self-ignition due to frictional electrostatic discharge from the pipeline is: Among them, P 总 denoted as , where i is the pressure level number, starting from 1 and increasing by natural numbers; I is the total number of pressure levels; J is the total number of leak orifice diameters; j is the leak orifice diameter number, starting from 1 and increasing by natural numbers; M is the number of ignitions in pipeline leakage experiments at a specific pressure level i and a specific leak orifice diameter j; and N is the number of pipeline leakage experiments at a specific pressure level i and a specific leak orifice diameter j. Among them, P i The probability of self-ignition of pipeline leakage under a specific pressure and a specific leakage orifice diameter; i is the pressure level number, starting from 1 and increasing by natural numbers; j is the leakage orifice diameter number, starting from 1 and increasing by natural numbers; J is the total number of leakage orifice diameters; M is the number of ignitions in pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j; N is the number of pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j. Among them, P j The probability of self-ignition of pipeline leakage under a specific pressure and a specific leakage orifice diameter; i is the pressure level number, starting from 1 and increasing by natural numbers; j is the leakage orifice diameter number, starting from 1 and increasing by natural numbers; I is the total number of pressure levels; M is the number of ignitions in pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j; N is the number of pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j.

[0014] Furthermore, the formula for calculating the fire protection effect of the obstruction is: E1=((H 前 -H 后 ) / H 前 )×100% (4) E1 represents the protective effect of the shield against fire heat radiation, with a value between 0% and 100%; H 前 The value is measured by a thermal radiation sensor directly in front of the obstruction, in km / m. 2 H 后 The value is measured by a thermal radiation sensor directly in front of the obstruction, in km / m. 2 ; E2=((P 前 -P 后 ) / P 前 )×100% (5) E2 represents the protective effect of the shield against explosive overpressure, with a value between 0% and 100%; P 前 The value measured by the pressure sensor directly in front of the obstruction, in kPa; P 后 The value measured by the pressure sensor directly in front of the obstruction is in kPa.

[0015] This invention can simulate fire and explosion scenarios in combustible gas pipelines with leaks of different sizes, different combustible mixing ratios, and different shielding conditions, comprehensively covering various situations that may actually be encountered, and achieving accurate assessment of the fire and explosion risks of combustible gas pipelines. This invention can not only conduct jet fire experiments and vapor cloud explosion experiments, but also triboelectric self-ignition probability experiments, comprehensively assessing the fire and explosion risks of combustible gas pipelines. This multi-type experimental capability makes the device more applicable and flexible. Experimental research using this invention can provide a deeper understanding of the mechanisms and patterns of combustible gas pipeline leakage accidents, providing a scientific basis for developing more effective protective measures. At the same time, this will greatly improve our level of natural gas pipeline safety management, ensuring the safe and reliable supply of energy. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Figure 2 This is a schematic diagram of the monitoring device and the obstruction of the present invention.

[0018] Figure 3 This is the pressure versus time curve of the present invention.

[0019] Figure 4 This is the curve showing the change in thermal radiation flux over time according to the present invention.

[0020] In the diagram: 1. Pipeline, 2. Natural gas tank, 3. Nitrogen tank, 4. Pressure gauge, 5. Leak valve, 6. Ignition device, 7. Vent pipe, 8. Gas detector, 9. Obstruction, 10. Thermal radiation sensor, 11. Pressure sensor, 13. Control terminal, 14. Pipeline mixer, 15. Medium tank. Detailed Implementation

[0021] like Figure 1 As shown, the present invention includes a pipeline 1, a natural gas tank 2, a medium tank 15, a nitrogen tank 3, a leak valve 5 connected to the pipeline 1, several monitoring devices arranged around the leak valve 5, a control terminal 13 connected to the monitoring devices, a vent pipe 7 and a pressure gauge 4 arranged on the pipeline 1, and a gas detector 8 arranged on the vent pipe 7. One end of the pipeline 1 is connected to the natural gas tank 2, the nitrogen tank 3 and the medium tank 15 respectively.

[0022] It also includes a pipeline mixer 14 connected to the natural gas tank 2 and the medium tank 15 respectively, and the pipeline mixer 14 is connected to the pipeline 1. The pipeline mixer 14 has two gas inlets, one of which is connected to the natural gas tank 2, and the other gas inlet is connected to the medium tank 15. The medium tank 15 is used to supply combustible gas, which generally includes methane, ethane, hydrogen, etc., and a suitable combustible gas can be selected according to the experimental needs.

[0023] A dual-control proportional valve (not shown in the figure) is also installed between the natural gas tank 2, the medium tank 15, and the pipeline mixer 14. This dual-control proportional valve enables both flow and pressure control, which is crucial for systems requiring precise control of the medium mixing ratio. During the mixing process of natural gas and the medium, adjusting the opening of the dual-control proportional valve ensures that natural gas and the medium enter the pipeline mixer 14 in a predetermined ratio, thereby achieving a stable and consistent gas or liquid composition after mixing.

[0024] An igniter 6 is installed above the leakage valve 5, and the igniter 6 is connected to the control terminal 13.

[0025] Nitrogen tank 3 is used to purge combustible gas or air from pipeline 1 to prevent the formation of a combustible mixture in pipeline 1. Valves are installed on natural gas tank 2, nitrogen tank 3, and medium tank 15, and a valve is installed on vent pipe 7.

[0026] There are several leakage valves 5 with different sizes to simulate the combustion or explosion effects of leakage ports of different sizes. In this embodiment, there are three leakage valves 5 with diameters of 5mm, 25mm and 50mm respectively. The appropriate number and size of leakage valves can be selected according to the needs of the experiment.

[0027] like Figure 2 As shown, the monitoring devices are arranged in a ring around the leak valve 5. Several rings of monitoring devices are set around the leak valve 5. In this embodiment, three rings of monitoring devices are set, and the distances between them and the leak valve 5 are 50m, 100m and 150m, respectively. Eight monitoring devices are evenly arranged in each ring.

[0028] The monitoring device includes several fixed rods 12 and several sets of thermal radiation sensors 10 and pressure sensors 11 installed on the fixed rods 12. In this embodiment, each fixed rod 12 is provided with three sets of thermal radiation sensors 10 and pressure sensors 11, which are respectively installed at positions 10m, 20m and 50m above the ground.

[0029] Both the thermal radiation sensor 10 and the pressure sensor 11 are connected to the control terminal 13. The control terminal 13 is responsible for receiving the signals sent by these two sensors and performing corresponding processing and control based on these signals. The igniter 6 is connected to the control terminal 13, which can control the ignition time of the igniter 6 and generate different ignition voltages.

[0030] An obstruction 9 is installed between the monitoring device and the leakage valve 5 to measure the values ​​of the heat radiation sensor 10 and pressure sensor 11 behind the obstruction 9. The obstruction 9 is vertically installed on the ground and can be a solid wall, glass, cotton cloth, or steel plate. Different sizes and placement distances from the leakage valve 5 can be selected according to experimental needs. Experimental data can be analyzed to compare changes in heat radiation and pressure values ​​under different conditions, thereby evaluating the protective effect of obstructions of different sizes and materials against the hazards of flammable gas fires and explosions. The obstruction 9 can simulate obstacles that may exist in the actual environment, such as buildings, trees, and vehicles.

[0031] Different obstructions 9 are placed at intervals around the leakage valve 5, such as obstructions of different thicknesses or materials. The area of ​​the obstructions is usually not less than 1m². 2 When placing multiple obstructions, the obstructions must not overlap. That is, the leakage valve 5 should be directly in front of the obstruction 9, and there should be no other obstruction 9 between the obstruction 9 and the leakage valve 5. Furthermore, a set of thermal radiation sensors 10 and a set of pressure sensors 11 should be installed directly in front of and behind the obstructions, respectively.

[0032] The above-mentioned experimental apparatus for fire and explosion hazards of combustible gas transport pipelines can conduct triboelectric self-ignition probability tests, jet fire tests, and vapor cloud explosion tests. The experimental methods for each test are described in detail below.

[0033] Experimental method for triboelectric self-ignition probability test: S1. Set up the above-mentioned experimental device for fire and explosion hazards of combustible gas conveying pipelines; S2. Open the valve of the venting pipe 7 and the valve of the nitrogen tank 3 to inject nitrogen into the pipeline 1. At the same time, closely monitor the reading of the gas detector 8. When the oxygen content in the gas measured by the gas detector 8 drops to the target content, close the valve of the nitrogen tank 3. In this step, the target oxygen content is less than 2%. S3. Inject combustible gas into pipeline 1 to replace the nitrogen in pipeline 1. When the nitrogen content in the gas measured by gas detector 8 reaches the target nitrogen content, it indicates that the replacement process is complete. Close the valve of vent pipe 7. Continue to inject combustible gas into pipeline 1. When the reading displayed on pressure gauge 4 reaches the target pressure, stop injecting combustible gas into pipeline 1. In this step, the target pressure in pipeline 1 is 6 MPa. In this step, the target nitrogen content is less than 2%. S4. Start the control terminal 13, activate the software related to the monitoring device, and start real-time monitoring and recording of relevant data; set the ignition voltage of the igniter 6 through the control terminal 13; in this step, the control terminal activates the software program related to the thermal radiation sensor 11 and the pressure sensor 12, and starts real-time monitoring and recording of relevant data. S5. Open the valve of the leakage valve 5 to allow the combustible gas in the pipeline 1 to leak; in this step, the valve of the leakage valve 5 with a diameter of 5mm is opened; S6. If self-ignition occurs during the leakage process, wait for the flame to be completely extinguished, save the data of the monitoring device recorded by the control terminal 13, and perform necessary processing and analysis; in this step, the control terminal 13 saves the data recorded by the thermal radiation sensor 11 and the pressure sensor 12; if self-ignition does not occur, repeat steps 1-5. S7. Repeat steps 2-6 and conduct tests under different diameter conditions for the leakage valve 5. In this step, tests were conducted on two types of leakage valve 5 with diameters of 25mm and 50mm respectively. S8. Repeat steps 2-7 to conduct tests under different pressure conditions in the pipeline; in this step, set the target pipeline pressure in step 4 to 7MPa, 8MPa, 9MPa and 10MPa at one time. S9. Statistically analyze the number of experiments and other relevant data to calculate the self-ignition probability and total self-ignition probability under different pressure levels and different leakage orifice diameters.

[0034] The probability of self-ignition due to frictional electrostatic discharge from a pipeline leak can be expressed by the following probability formula: Among them, P 总 denoted as , where is the total probability of self-ignition in a pipeline leak; i is the pressure level number, starting from 1 and increasing by natural numbers; I is the total number of pressure levels; J is the total number of leak orifice diameters; j is the leak orifice diameter number, starting from 1 and increasing by natural numbers; M is the number of ignitions in a pipeline leak experiment at a specific pressure level i and a specific leak orifice diameter j; and N is the number of pipeline leak experiments at a specific pressure level i and a specific leak orifice diameter j.

[0035] Among them, P i The probability of self-ignition of pipeline leakage under a specific pressure and a specific leakage orifice diameter; i is the pressure level number, starting from 1 and increasing by natural numbers; j is the leakage orifice diameter number, starting from 1 and increasing by natural numbers; J is the total number of leakage orifices; M is the number of ignitions in pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j; N is the number of pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j.

[0036] Among them, P jThe probability of self-ignition of pipeline leakage under a specific pressure and a specific leakage orifice diameter; i is the pressure level number, starting from 1 and increasing by natural numbers; j is the leakage orifice diameter number, starting from 1 and increasing by natural numbers; I is the total number of pressure levels; M is the number of ignitions in pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j; N is the number of pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j.

[0037] Experimental method for jet fire experiment: S1. Set up the above-mentioned experimental device for fire and explosion hazards of combustible gas conveying pipelines; S2. Open the valve of the venting pipe 7 and the valve of the nitrogen tank 3 to inject nitrogen into the pipeline 1. At the same time, closely monitor the reading of the gas detector 8. When the oxygen content in the gas measured by the gas detector 8 drops to the target content, close the valve of the nitrogen tank 3. In this step, the target oxygen content is less than 2%, which indicates that the nitrogen replacement process has been completed and the air in the pipeline has been effectively removed. This step aims to replace any residual air in the pipeline, thereby eliminating the potential explosion risk. S3. Inject combustible gas into pipeline 1 to replace the nitrogen in pipeline 1. When the nitrogen content in the gas measured by gas detector 8 reaches the target nitrogen content, it indicates that the replacement process is complete. Close the valve of vent pipe 7. Continue to inject combustible gas into pipeline 1. When the reading displayed by pressure gauge 4 reaches the target pressure, stop injecting combustible gas into pipeline 1. In this step, the target nitrogen content is less than 2%. In this step, the target pressure in pipeline 1 is 6 MPa. According to experimental needs, inject combustible gas into pipeline 1. The combustible gas can be natural gas in natural gas tank 2 or combustible gas in medium tank 15, or it can be a mixture of natural gas in natural gas tank 2 and combustible gas in medium tank 15. When it is necessary to inject mixed gas into pipeline 1, open the valve of natural gas tank 2 and the valve of medium tank 15. According to the predetermined mixing ratio of natural gas and combustible gas medium, inject the gas into pipeline mixer 14. Pipeline mixer 14 fully mixes natural gas and combustible gas medium. Open the valve of pipeline mixer 14 and inject the mixed natural gas into pipeline 1. S4. Start the control terminal 13, activate the software related to the monitoring device, and start real-time monitoring and recording of relevant data; set the ignition voltage of the igniter 6 through the control terminal 13; in this step, the control terminal activates the software program related to the thermal radiation sensor 11 and the pressure sensor 12, and starts real-time monitoring and recording of relevant data; the ignition voltage of the igniter 6 is 24V. S5. Open the valve of leakage valve 5 to allow the mixed natural gas to begin leaking; in this step, the valve of leakage valve 5 with a diameter of 5mm is opened; S6. Ignite 6 to start ignition. In this step, igniter 6 is started to ignite at the same time as leakage valve 5 starts to leak. S7. After the jet flame is extinguished, save the data recorded by the monitoring device in the control terminal 13 and perform necessary processing and analysis; in this step, the control terminal 13 saves the data recorded by the thermal radiation sensor 11 and the pressure sensor 12. S8. Repeat steps 2-8 to conduct tests under different diameter conditions for the leakage valve 5. In this step, tests were conducted on two types of leakage valve 5 with diameters of 25mm and 50mm respectively. S9, the control terminal 13 processes the collected data to obtain, for example... Figure 3 The pressure versus time curve shown Figure 4 The curves showing the change in thermal radiation flux over time are shown below. S10. Compare the thermal radiation sensor data before and after each shield 9, and use the formula to calculate the fire protection effect of the shield.

[0038] Experimental method for vapor cloud explosion test: S1. Set up the above-mentioned experimental device for fire and explosion hazards of combustible gas conveying pipelines; S2. Open the valve of the venting pipe 7 and the valve of the nitrogen tank 3 to inject nitrogen into the pipeline 1. At the same time, closely monitor the reading of the gas detector 8. When the oxygen content in the gas measured by the gas detector 8 drops to the target oxygen content, close the valve of the nitrogen tank 3. In this step, the target oxygen content is less than 2%. S3. Inject combustible gas into pipeline 1 to replace the nitrogen in pipeline 1. When the nitrogen content in the gas measured by gas detector 8 reaches the target nitrogen content, close the valve of vent pipe 7. Continue to inject combustible gas into pipeline 1. When the reading displayed on pressure gauge 4 reaches the target pressure, stop injecting combustible gas into pipeline 1. In this step, the target nitrogen content is less than 2%. In this step, the target pressure in pipeline 1 is 6 MPa. S4. Start the control terminal 13, activate the software related to the monitoring device, and start real-time monitoring and recording of relevant data; set the ignition voltage of the igniter 6 through the control terminal 13; in this step, the control terminal activates the software program related to the thermal radiation sensor 11 and the pressure sensor 12, and starts real-time monitoring and recording of relevant data; the ignition voltage of the igniter 6 is 24V. S5. Open the valve of the leakage valve 5 to allow the combustible gas in the pipeline 1 to leak; in this step, the valve of the leakage valve 5 with a diameter of 5mm is opened; S6. Ignite 6 to start ignition; in this step, igniter 6 is started to start ignition 30 seconds after leakage from leakage valve 5. S7. After the steam cloud explosion flame is extinguished, save the data recorded by the monitoring device in the control terminal 13 and perform necessary processing and analysis; in this step, the control terminal 13 saves the data recorded by the thermal radiation sensor 11 and the pressure sensor 12. S8. Repeat steps 2-7 and conduct tests under different diameter conditions for the leakage valve 5. In this step, tests were conducted on two types of leakage valve 5 with diameters of 25mm and 50mm respectively. S9, the control terminal 13 processes the collected data to obtain pressure versus time curves and heat radiation flux versus time curves; S10. Compare the thermal radiation sensor data before and after each shield 9, and use the formula to calculate the fire protection effect of the shield.

[0039] The fire protection effect of a barrier can be expressed by the following probability formula: E1=((H 前 -H 后 ) / H 前 )×100% (4) E1 represents the protective effect of the shield against fire heat radiation, with a value between 0% and 100%; H 前 The value is measured by a thermal radiation sensor directly in front of the obstruction, in km / m. 2 H 后 The value is measured by a thermal radiation sensor directly in front of the obstruction, in km / m. 2 .

[0040] E2=((P 前 -P 后 ) / P 前 )×100% (5) E2 represents the protective effect of the shield against explosive overpressure, with a value between 0% and 100%; P 前 The value measured by the pressure sensor directly in front of the obstruction, in kPa; P 后 The value measured by the pressure sensor directly in front of the obstruction is in kPa.

[0041] After the experiment, based on the actual on-site experimental conditions, existing pipeline fire and explosion calculation formulas can be used to theoretically calculate the heat radiation flux and overpressure values ​​at different locations. These theoretical calculation results can be compared with the actual experimental data obtained from the control console to evaluate the conservatism of existing pipeline fire and explosion theoretical calculation formulas. The specific calculation formula for the conservatism assessment is as follows: Q1=((H 计算 -H 试验 ) / H 试验 )×100% (6) Where Q1 represents the conservatism of existing theoretical calculation formulas for pipeline fires compared to actual experiments, with a value between -100% and 100%; H 计算 These are theoretically calculated thermal radiation values, in km / m. 2 H 试验 The measured thermal radiation values ​​are in km / m. 2 .

[0042] Q2=((P 计算 -P 试验 ) / P 试验 )×100% (7) Wherein, Q2 represents the conservatism of existing theoretical calculation formulas for pipeline explosions compared to actual experiments, with a value between -100% and 100%; H 计算 The pressure values ​​are obtained from theoretical calculations, and the units are kPa and H. 试验 The pressure value is measured in kPa.

Claims

1. An experimental apparatus for testing the fire and explosion hazards of combustible gas transport pipelines, characterized in that, It includes a natural gas tank, a medium tank, a nitrogen tank, a pipeline, a leak valve connected to the pipeline, several monitoring devices arranged around the leak valve, a control terminal connected to the monitoring devices, a vent pipe and a pressure gauge arranged on the pipeline, and a gas detector arranged on the vent pipe. One end of the pipeline is connected to the natural gas tank, the medium tank, and the nitrogen tank respectively.

2. The experimental apparatus for fire and explosion hazards of combustible gas conveying pipelines according to claim 1, characterized in that, It also includes a mixer connected to the pipelines of the natural gas tank and the medium tank respectively, and the pipeline mixer is connected to the pipeline.

3. The experimental apparatus for fire and explosion hazards of combustible gas conveying pipelines according to claim 1, characterized in that, An igniter is installed above the leakage valve, and the igniter is connected to the control terminal.

4. The experimental apparatus for fire and explosion hazards of combustible gas conveying pipelines according to claim 1, characterized in that, The monitoring devices are arranged in a ring around the leak valve, with several rings of monitoring devices surrounding the leak valve.

5. The experimental apparatus for fire and explosion hazards of combustible gas conveying pipelines according to claim 1 or 4, characterized in that, The monitoring device includes a fixed rod and several sets of thermal radiation sensors and pressure sensors mounted on the fixed rod. Both the thermal radiation sensors and the pressure sensors are connected to the control terminal.

6. The experimental apparatus for fire and explosion hazards of combustible gas conveying pipelines according to claim 1, characterized in that, An obstruction is provided between the leakage valve and the detection device.

7. A method for testing the fire and explosion hazards of combustible gas transport pipelines, characterized in that, Includes the following steps: S1. Set up a fire and explosion hazard test device for any of the combustible gas conveying pipelines as described in claims 1-6; S2. Open the valve of the venting pipe, then open the valve of the nitrogen tank to inject nitrogen into the pipeline. When the oxygen content in the gas measured by the gas detector drops to the target oxygen content, close the valve of the nitrogen tank. S3. Inject combustible gas into the pipeline. After the nitrogen content in the gas measured by the gas detector drops to the target nitrogen content, close the valve of the vent pipe and continue to inject combustible gas into the pipeline. When the pressure value displayed on the pressure gauge reaches the target pressure, stop injecting combustible gas into the pipeline. S4. Start the control terminal, activate the software program related to the monitoring device, and begin real-time monitoring and recording of relevant data; S5. Open the leak valve to allow the combustible gas in the pipeline to leak out; S6. After the flame is extinguished, save the data of the monitoring device recorded by the control terminal; S7. Repeat steps S2-S6 to conduct tests under different diameters of the leakage valve and different pressure conditions of the pipeline. S8. The control terminal processes the collected data and calculates the fire protection effect of the obstruction and the probability of self-ignition due to frictional static electricity from pipeline leakage.

8. The experimental method for fire and explosion hazards of combustible gas transportation pipelines according to claim 7, characterized in that, An ignition step is also included between step S5 and step S6.

9. The experimental method for fire and explosion hazards of combustible gas conveying pipelines according to claim 7, characterized in that, The formula for calculating the probability of self-ignition due to frictional electrostatic discharge from a pipeline leak is: Among them, P 总 denoted as , where i is the pressure level number, starting from 1 and increasing by natural numbers; I is the total number of pressure levels; J is the total number of leak orifice diameters; j is the leak orifice diameter number, starting from 1 and increasing by natural numbers; M is the number of ignitions in pipeline leakage experiments at a specific pressure level i and a specific leak orifice diameter j; and N is the number of pipeline leakage experiments at a specific pressure level i and a specific leak orifice diameter j. Among them, P i The probability of self-ignition of pipeline leakage under a specific pressure and a specific leakage orifice diameter; i is the pressure level number, starting from 1 and increasing by natural numbers; j is the leakage orifice diameter number, starting from 1 and increasing by natural numbers; J is the total number of leakage orifice diameters; M is the number of ignitions in pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j; N is the number of pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j. Among them, P j The probability of self-ignition of pipeline leakage under a specific pressure and a specific leakage orifice diameter; i is the pressure level number, starting from 1 and increasing by natural numbers; j is the leakage orifice diameter number, starting from 1 and increasing by natural numbers; I is the total number of pressure levels; M is the number of ignitions in pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j; N is the number of pipeline leakage experiments under a specific pressure level i and a specific leakage orifice diameter j.

10. The experimental method for fire and explosion hazards of combustible gas conveying pipelines according to claim 7, characterized in that, The formula for calculating the fire protection effect of the obstruction is: E1=((H 前 -H 后 ) / H 前 )×100% (4) E1 represents the protective effect of the shield against fire heat radiation, with a value between 0% and 100%; H 前 The value is measured by a thermal radiation sensor directly in front of the obstruction, in km / m. 2 H 后 The value is measured by a thermal radiation sensor directly in front of the obstruction, in km / m. 2 ; E2=((P 前 -P 后 ) / P 前 )×100% (5) E2 represents the protective effect of the shield against explosive overpressure, with a value between 0% and 100%; P 前 The value measured by the pressure sensor directly in front of the obstruction, in kPa; P 后 The value measured by the pressure sensor directly in front of the obstruction is in kPa.

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