A CO2 pipeline fracture expansion and pipe decompression wave propagation velocity measurement system and working method

Abstract

A system and operating method for measuring the fracture propagation velocity of a CO2 pipeline and the propagation velocity of a decompression wave within the pipeline, and the method relate to the field of CO2 pipeline transportation safety. The measurement system includes a weighing scale, a dewar tank, a plunger pump, a silicone rubber heating belt, a rubber-plastic insulation layer, a high-frequency pressure sensor, a phase change observation kettle, a T-type armored thermocouple, a test pipeline, a voltage-regulating power supply and an enameled wire system, and a data acquisition system. The measurement system of the present invention can conduct experiments to measure the fracture velocity of a pipeline and the propagation velocity of a CO2 decompression wave within the pipeline for CO2 in different phases and transmission pipelines. The device can test the fracture propagation velocity and the propagation velocity of a decompression wave in CO2 transmission pipelines of different diameters under different transmission phases. The device is characterized by simple installation, high test accuracy, and safety and reliability.

Description

Technical Field

[0001] The present invention belongs to the field of CO2 pipeline transportation safety, and in particular relates to a system for capturing rupture velocity and measuring decompression waves of a CO2 transportation pipeline. Background Art

[0002] CO2 pipeline safety is crucial for the industrialization and commercial application of carbon capture, utilization, and storage (CCUS) technology. In actual industrial applications, CO2 is often transported in supercritical and liquid states. However, if a supercritical or liquid CO2 pipeline fails and ruptures, the pressure inside the pipeline does not drop directly to atmospheric pressure. Instead, a decompression wave propagates from the fracture to both ends and propagates further. Simultaneously, the decompression of the medium within the pipeline flashes, causing boiling liquid expansion and steam explosion, resulting in secondary high-pressure-driven cracks that propagate from the crack initiation point to both sides of the pipeline. When the crack propagation driving force (the gas pressure at the crack tip) exceeds the decompression wave propagation velocity, the crack will continue to propagate. When the crack propagation driving force is greater than or equal to the decompression wave propagation velocity, the crack will propagate steadily. When the crack propagation driving force is less than the decompression wave propagation velocity, the crack will slow down and eventually stop. Long-range crack development in CO2 pipelines can cause significant catastrophic damage and economic losses.

[0003] To investigate the fracture propagation velocity and decompression wave propagation patterns in CO2 pipelines, a dedicated platform for measuring these velocities is urgently needed. This platform can quantitatively and qualitatively analyze CO2 transport volume and provide a basis for determining the crack arrest toughness of CO2 pipelines. This invention provides a CO2 pipeline fracture propagation and decompression wave propagation velocity measurement system capable of measuring the crack propagation velocity and decompression wave propagation velocity after a CO2 pipeline fracture. Summary of the Invention

[0004] To fill the technical gap in measuring the fracture propagation velocity and decompression wave propagation velocity of medium-sized CO2 pipelines transporting CO2 from CO2 capture sites to collection sites, the present invention provides a device and experimental method for conducting fracture simulation experiments directly on pipe sections. Using this experimental platform, fracture experiments can be safely conducted on pipe sections, and crack propagation can be detected. At the same time, the phenomenon of decompression phase transition in the pipe can be observed, and the propagation law of decompression waves can be detected. The experimental device has a simple structure and is easy to use.

[0005] To achieve the above object, the present invention adopts the following scheme:

[0006] A system for measuring the propagation velocity of a CO2 pipeline fracture and the decompression wave in the pipeline, the measuring system comprising a digital weighing scale 1, a CO2 dewar cylinder 2, a plunger pump 3, a manual valve, a rubber heating belt 5, an experimental main pipeline 7, a pointer pressure gauge 8, a high-frequency pressure sensor, a T-type armored thermocouple, a phase change observation kettle 11, a data acquisition box 12, a data acquisition system 13, a first crack stop ring 14-1, a second crack stop ring 14-2, a voltage regulating power supply and enameled wire system 15, a prefabricated defect 16, a test pipeline 17, an indicator light 18, an adjustable DC power supply 19, and a copper enameled wire 20.

[0007] The test pipe 17 is connected to the rear of the experimental main pipe 7 through a flange.

[0008] The phase change observation kettle 11 is installed in the middle of the experimental main pipeline 7 and is used to observe the phase change of CO2 in the pipeline;

[0009] The high-frequency pressure sensor and the T-type armored thermocouple need to be set in pairs on the test pipe 17 and the experimental main pipe 7.

[0010] The CO2 Dewar cylinder 2 provides a gas source for the pipeline rupture experiment, which is injected into the experimental main pipeline 7 through the plunger pump 3. The rubber heating belt 5 is used to heat the CO2 in the pipeline to control the CO2 phase, and the insulating rubber and plastic reduce the thermal convection effect between the pipeline and the surrounding environment; the high-frequency pressure sensor provided on the experimental main pipeline 7 and the test pipeline 17 is used to measure the value of the CO2 pressure change in the pipeline; the T-type armored thermocouple installed on the experimental main pipeline 7 and the test pipeline 17 is used to measure the value of the CO2 temperature change in the pipeline; the voltage regulating power supply and enameled wire system 15 are fixed at fixed intervals in the circumferential direction of the test pipeline 17 to test the speed of crack propagation after the pipeline 17 is broken; the data acquisition system 13 is used to record the acquisition values of the high-frequency pressure sensor, the measurement values of the T-type armored thermocouple, and the fracture time of adjacent enameled wires.

[0011] The digital weighing scale 1 is placed under the CO2 dewar cylinder 2 to record the weight of CO2 filled into the pipeline;

[0012] The data acquisition system 13 is connected to the data acquisition box 12, and the data acquisition box 12 is respectively connected to the high-frequency pressure sensor, the T-type armored thermocouple, the voltage regulating power supply and the enameled wire system 15;

[0013] The first crack arresting ring 14 - 1 and the second crack arresting ring 14 - 2 are respectively installed at equal distances from both ends of the test pipe 17 to verify whether the developed crack arresting device can achieve crack arresting.

[0014] The pointer pressure gauge 8 is installed on the experimental main pipeline 7.

[0015] The prefabricated defect 16 is arranged in the middle of the test pipe 17 .

[0016] The number of the voltage-regulating power supply and enameled wire systems 15 is even and is symmetrically arranged with the prefabricated defect 16 as the center; each voltage-regulating power supply and enameled wire system 15 includes an indicator light 18, an adjustable DC power supply 19 and a copper enameled wire 20. The indicator light 18 and the adjustable DC power supply 19 are connected through the copper enameled wire 20 to form a closed loop. The indicator light 18 is used to identify whether the circuit has formed a path.

[0017] Furthermore, the phase change observation kettle 11 includes a mother flange 11-1, a sub-flange 11-2, a hexagon socket bolt 11-3, a cover plate 11-4, a transparent glass 11-5, a forging 11-6 and a polytetrafluoroethylene seal 11-7. The two opposite surfaces of the forging 11-6 are connected to each other and are used to connect to the experimental main pipeline 7 or the test pipeline 17 through the sub-flange 11-2 or the mother flange 11-1. The sub-flange 11-2 or the mother flange 11-1 is welded to the experimental main pipeline 7 or the test pipeline 17, and the mother flange 11-1 is sealed with the sub-flange 11-2 by bolts and nuts. The two opposite front and rear surfaces of the forging 11-6 are connected and are used to install transparent glass 11-5 and polytetrafluoroethylene seal 11-7. The transparent glass 11-5 is embedded in the forging 11-6 and is connected to the forging 11-6 by the cover 11-4 and the hexagon socket bolt 11-3. The phase change observation kettle 11 as a whole can withstand a pressure of more than 20 MPa.

[0018] Furthermore, the rubber-plastic insulation layer 6 is wrapped around the outer wall of the experimental main pipeline 7 through a clamp, and the outer wall of the rubber-plastic insulation layer 6 is wrapped with aluminum foil. The rubber-plastic insulation layer 6 and the aluminum foil can reduce the convective heat exchange intensity between the surrounding environment and the pipeline.

[0019] Furthermore, the angle between the high-frequency pressure sensor arranged on the experimental main pipeline 7 and the straight line of the center of the circle and the vertical distance is 0°~15°, preferably 0°; the angle between the T-type armored thermocouple arranged on the experimental main pipeline 7 and the straight line of the center of the circle and the vertical distance is 90°~105°, preferably 90°.

[0020] Furthermore, the angle between the prefabricated defect and the straight line and the vertical distance from the center of the circle is 0°~5°, preferably 0°; the angle between the high-frequency pressure sensor arranged on the test pipe 17 and the straight line and the vertical distance from the center of the circle is 0°~95°, preferably 90°; the angle between the T-type armored thermocouple arranged on the experimental main pipe 7 and the straight line and the vertical distance from the center of the circle is 315°~320°, preferably 315°.

[0021] A method for measuring the propagation velocity of a CO2 pipeline fracture and a decompression wave in the pipeline comprises the following steps:

[0022] S1: Fabricate a test pipe 17 with prefabricated defects 16. Connect an adjustable DC power supply 19 with varying voltages to both sides of a copper enameled wire 20, and connect an indicator light 18 in series to form a closed loop. The voltage-regulated power supply and enameled wire system are fixed circumferentially around the test pipe 17. Open a manual valve to release the gaseous CO2 from the CO2 dewar cylinder 2 into the main experimental pipe 7. The purge operation ultimately lowers the temperature of the main experimental pipe 7 to below -15°C, and the manual valve is closed.

[0023] S2: Start the data acquisition system 13, record the initial display value of the digital weighing scale 1, and sequentially open the manual valve and plunger pump 3 to inject the liquid CO2 from the CO2 dewar cylinder 2 into the experimental main pipeline 7 via the plunger pump 3. Based on the phase behavior experiment to be conducted, control the mass of CO2 injected into the experimental main pipeline 7 by the plunger pump 3, and fill the required filling amount according to the display value of the digital weighing scale 1. Close the plunger pump 3 and the manual valve in sequence to complete the liquid CO2 filling process.

[0024] S3: Set the heating temperature of the rubber heating belt 5 to control the temperature of the CO2 injected into the experimental main pipeline 7. As the temperature of the liquid CO2 rises, the pressure will also increase. When the pressure in the pipe reaches the theoretical failure pressure value of the defective test pipeline 17, turn off the rubber heating belt 5.

[0025] S4: When the pressure in the experimental main pipeline 7 exceeds the theoretical failure pressure of the defective test pipeline 17, CO2 will be ejected from the prefabricated defect 16. The instantaneous decompression of the ejection port causes the CO2 near the crack to form a boiling liquid, which expands into steam and explodes, driving the crack to extend toward both sides of the prefabricated defect 16. At the same time, a decompression wave is formed at the prefabricated defect 16 and propagates toward both sides of the crack.

[0026] S5: As the crack expands, it expands due to the pressure within the test tube, breaking the enameled wires in the voltage-regulating power supply and enameled wire system 15, which are fixed to the outer tube wall. As the crack propagates to the right, the voltage-regulating power supply and enameled wire system on the right side are successively broken. The data acquisition system 13 records the voltage values collected on both sides of the voltage-regulating power supply and enameled wire system on the right side, and calculates the crack growth rate in the test tube based on the time corresponding to the voltage drop.

[0027] S6: The data acquisition system 13 records the CO2 pressure change value in the experimental main pipeline 7 and the test pipeline 17 when the crack propagates as measured by the high-frequency pressure sensor, and the CO2 temperature change value in the experimental main pipeline 7 and the test pipeline 17 when the crack propagates as measured by the T-type armored thermocouple.

[0028] S7: The phase change observation kettle 11 can be used to observe with the human eye or record with a high-speed camera the phase change pattern of CO2 in the experimental main pipeline 7 after the test pipeline 17 is broken.

[0029] Beneficial effects of the present invention:

[0030] The present invention uses a plunger pump to fill a fixed amount of liquid CO2 into the experimental main pipeline and test pipeline, which is then heated to the target temperature by a heating system. The rubber and plastic insulation material prevents heat convection between the pipeline and the external environment. When the pressure inside the pipeline exceeds the theoretical failure pressure of the test pipeline with a prefabricated defect, cracks form at the defect in the test pipeline and break and expand toward both ends. The time it takes for the specially designed adjacent enameled wires fixed to the outside of the test pipe wall to break can be used to calculate the pipeline rupture speed. High-frequency pressure sensors installed on the main pipeline and the test pipeline can measure the propagation speed of the CO2 decompression wave in the pipeline. A specially designed high-pressure-resistant transparent autoclave can be used to observe the phase change law during the decompression process of the CO2 in the pipeline. By injecting different masses of liquid CO2 into the main pipeline, pipeline rupture extension and decompression wave experiments can be carried out at different temperatures, different phases, different pipe sizes, and different geometric defect sizes. The experimental cycle is short, the test efficiency is high, and the test accuracy is high. The present invention can guide the safe design of CO2 transportation pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a structural diagram of a system for measuring the fracture propagation velocity and decompression wave velocity of a CO2 transmission pipeline.

[0032] Figure 2 The transparent kettle 11 is used to observe the phase change of CO2 in the tube during the experiment.

[0033] Figure 3 This is the installation position of the high-frequency pressure sensor and the T-type armored thermocouple on the main pipeline. The angle between the high-frequency pressure sensor and the vertical distance between the straight line and the center of the circle is 0°; the angle between the T-type armored thermocouple 10 and the vertical distance between the straight line and the center of the circle is 90°.

[0034] Figure 4 Installation locations of high-frequency pressure sensors 9, 9-5, 9-6, and T-type armored thermocouples 10, 10-5, 10-6, and 10-6 on the test pipe. Prefabricated defect 16 is located along the top of the test pipe cross section. The angle between the prefabricated defect and the center of the circle and the vertical distance is 0°; the angle between the high-frequency pressure sensor and the center of the circle and the vertical distance is 90°; and the angle between the T-type armored thermocouple and the center of the circle and the vertical distance is 315°.

[0035] Figure 5 It is a composition diagram of a voltage-regulating power supply and an enameled wire system. The system only needs to form a closed circuit on the test pipe. The indicator light 18 and the adjustable DC power supply 19 are not set at the prefabricated defect 16.

[0036] In the figure: 1 digital display weighing scale; 2 CO2 dewar cylinder; 3 plunger pump; 4-1 first manual valve; 4-2 second manual valve; 4-3 third manual valve; 4-4 fourth manual valve; 4-5 fifth manual valve; 4-6 sixth manual valve; 5 rubber heating belt; 6 rubber and plastic insulation layer; 7 experimental main pipeline; 8 pointer pressure gauge; 9-1 first high-frequency pressure sensor; 9-2 second high-frequency pressure sensor; 9-3 third high-frequency pressure sensor; 9-4 fourth high-frequency pressure sensor; 9-5 fifth high-frequency pressure sensor; 9-6 sixth high-frequency pressure sensor; 9-7 seventh high-frequency pressure sensor; 10-1 first T-type armored thermocouple; 10-2 second T-type armored thermocouple; 10-3 third T-type armored thermocouple; 10-4 fourth T-type armored thermocouple; 10-5 fifth T-type armored thermocouple; 10-6 sixth T-type armored thermocouple; 10-7 seventh T-type armored thermocouple Galvanic couple; 11 Phase change observation kettle; 11-1 Female flange; 11-2 Sub-flange; 11-3 Hexagon socket bolt; 11-4 Cover plate; 11-5 Transparent glass; 11-6 Forging; 11-7 Polytetrafluoroethylene seal; 12 Data acquisition box; 13 Data acquisition system; 14-1 First crack stop ring; 14-2 Second crack stop ring; 15 Voltage regulating power supply and enameled wire system; 15-1 First voltage regulating power supply and enameled wire system; 15-2 Second voltage regulating power supply Source and enameled wire system; 15-3 Third regulated power supply and enameled wire system; 15-4 Fourth regulated power supply and enameled wire system; 15-5 Fifth regulated power supply and enameled wire system; 15-6 Sixth regulated power supply and enameled wire system; 15-7 Seventh regulated power supply and enameled wire system; 15-8 Eighth regulated power supply and enameled wire system; 16 Prefabricated defects; 17 Test pipeline; 18 Indicator light; 19 Adjustable DC power supply, 20 Insulated copper enameled wire. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be further described below in conjunction with specific embodiments and drawings.

[0038] Example 1

[0039] The following describes the process of testing the fracture propagation characteristics of a CO2 pipeline using a milling machine to create a 30 cm long, 2 cm wide, and 2 mm deep defect in the center of the test pipe, assuming the supercritical CO2 temperature is 35°C and the pressure is 8 MPa. The test pipe is a 3-meter-long, 96 mm inner diameter, 20-gauge seamless steel pipe with a wall thickness of 3 mm. The following describes the process of testing the fracture propagation characteristics of a CO2 pipeline using a milling machine to create a 30 cm long, 2 cm wide, and 2 mm deep defect in the center of the test pipe.

[0040] Reference Figure 1According to the present invention, a system for measuring the fracture extension and the propagation velocity of the decompression wave in a CO2 pipeline and a working method thereof include a digital weighing scale 1, a CO2 dewar cylinder 2, a plunger pump 3, a manual valve, a rubber heating belt 5, an experimental main pipeline 7, a pointer pressure gauge 8, a high-frequency pressure sensor, a T-type armored thermocouple, a phase change observation kettle 11, a data acquisition box 12, a data acquisition system 13, a crack arrest ring, a voltage regulating power supply and enameled wire system, a pipeline prefabricated defect 16, a test pipeline 17, an indicator light 18, an adjustable DC power supply 19 and a copper enameled wire 20.

[0041] Eight voltage-regulating power supplies and enameled wire systems 15 are arranged at intervals of L / 10 along the axial direction of the test pipe. The voltage-regulating power supplies and enameled wire systems are fixed to the test pipe 17 in the circumferential direction using 502 glue at intervals of L / 10.

[0042] The adjustable DC power supply 19 steps down the 12V DC voltage to 1-5V to distinguish the electrical signals at both ends of the first voltage-regulated power supply and enameled wire system 15-1 to the eighth voltage-regulated power supply and enameled wire system 15-8, so that the voltage values collected by the acquisition card are different.

[0043] The test pipe 17 is connected to the experimental main pipe 7 through a flange of PN160 specification. The test pipes 17 of different diameters can also be connected to the experimental main pipe 7 by processing a reducing flange.

[0044] Transparent glass 11-5 is alumina transparent glass, made of alumina, 25 cm long, 15 cm wide, and 3 cm thick.

[0045] The experimental main pipeline 7 is a high-pressure resistant pipeline with a total length of 15m, an inner diameter of 98mm, a wall thickness of 8mm, a material of 304 stainless steel, and a pressure bearing capacity of 16MPa.

[0046] The high-frequency pressure sensor is installed on the main experimental pipeline at intervals of 3.1m, with a collection frequency of 100KHz and a pressure bearing capacity of 16MPa.

[0047] The T-type armored thermocouples 10 are installed on the main experimental pipeline at intervals of 3.1 m, with a collection frequency of 10 Hz and a pressure resistance of 16 MPa.

[0048] The first crack stop ring 14 - 1 is installed at a distance of 10-30 cm from the left flange of the test pipe 17 , preferably 20 cm; the second crack stop ring 14 - 2 is installed at a distance of 10-30 cm from the right end flange of the test pipe 17 , preferably 20 cm.

[0049] The phase change observation kettle 11 is installed in the middle of the experimental main pipeline 7, 7.5 meters away from the left flange of the experimental main pipeline 7.

[0050] The thickness of the rubber-plastic insulation layer 6 is 2 cm.

[0051] The first manual valve 4 - 1 is a needle-type manual valve with M20*1.5 external threads at both ends, and is installed at the gas phase outlet of the CO2 Dewar tank cylinder 2 .

[0052] Second manual valve 4-2 is a needle-type manual valve with M20*1.5 external threads on both ends. It is installed at the liquid-phase outlet of CO2 dewar cylinder 2. An explosion-proof bellows is connected to second manual valve 4-2 at one end and to the material inlet of plunger pump 3 at the other. The material outlet of plunger pump 3 is connected to the external threads of third manual valve 4-3 via explosion-proof bellows. Second manual valve 4-2, third manual valve 4-3, and plunger pump 3 are used to control the entry of liquid CO2 from CO2 dewar cylinder 2 into experimental main pipeline 7.

[0053] The fourth manual valve 4-4 is installed at the inlet end of the experimental main pipeline 7. The first manual valve 4-1 and the fourth manual valve 4-4 are connected by an explosion-proof bellows. The passage between the first manual valve 4-1 and the fourth manual valve 4-4 is used to control the gaseous CO2 in the CO2 Dewar tank cylinder 2 to enter the experimental main pipeline 7.

[0054] The fifth manual valve 4-5 is provided on the experimental main pipeline 7 for pressure relief. The sixth manual valve 4-6 is provided at the end of the test pipeline 17 for further pressure relief.

[0055] The first manual valve 4-1, the second manual valve 4-2, the third manual valve 4-3, the fourth manual valve 4-4, and the fifth manual valve 4-5 are low-temperature, high-pressure needle valves, resistant to temperatures as low as -70°C and capable of withstanding pressures of 32 MPa. The sixth manual valve 4-6 is a low-temperature, high-pressure ball valve, with a ball core diameter of 25 mm, capable of withstanding pressures of 32 MPa and capable of withstanding temperatures as low as -100°C.

[0056] The pointer pressure gauge 8 is installed in the middle of the left side of the main experimental pipeline 7 by means of a threaded connection, 3.5 meters away from the left flange of the left section of the main pipeline. The pointer pressure gauge 8 is 1 meter away from the female flange 11-1.

[0057] Reference Figure 2 The first high-frequency pressure sensor 9-1, the second high-frequency pressure sensor 9-2, the third high-frequency pressure sensor 9-3, and the fourth high-frequency pressure sensor 9-4 are installed at 90° positions on the experimental main pipeline 7 at intervals of 3.1 meters and the signal lines are connected to the collection box 12.

[0058] The first T-type armored thermocouple 10-1, the second T-type armored thermocouple 10-2, the third T-type armored thermocouple 10-3, and the fourth T-type armored thermocouple 10-4 are respectively installed at the 0° direction position of the main pipeline 7 at a spacing of 3.1 meters and the signal lines are connected to the collection box 12.

[0059] Reference Figure 3 The fifth high-frequency pressure sensor 9-5, the sixth high-frequency pressure sensor 9-6, and the seventh high-frequency pressure sensor 9-6 are respectively installed at the 90° direction position of the test pipe 17, and the fifth T-type armored thermocouple 10-5, the sixth T-type armored thermocouple 10-6, and the seventh T-type armored thermocouple 10-7 are respectively installed at the 315° direction position of the test pipe 17 and the signal lines are connected to the collection box.

[0060] Reference Figure 4 According to the present invention, a CO2 pipeline fracture propagation and decompression wave detection test system and operating method thereof uses an insulated copper enameled wire 20 to connect a DC 5V indicator light and an adjustable DC 5V power supply in series. The DC adjustable 5V power supply can receive a DC 12V voltage and output a DC 0-5V voltage. Adjust the DC output end of the first voltage-regulated power supply and enameled wire system 15-1 to 4.0V, adjust the output end of the second voltage-regulated power supply and enameled wire system 15-2 to 4.1V, adjust the output end of the third voltage-regulated power supply and enameled wire system 15-3 to 4.2V, adjust the output end of the fourth voltage-regulated power supply and enameled wire system 15-4 to 4.3V, adjust the output end of the fifth voltage-regulated power supply and enameled wire system 15-5 to 4.4V, adjust the output end of the sixth voltage-regulated power supply and enameled wire system 15-6 to 4.5V, adjust the output end of the seventh voltage-regulated power supply and enameled wire system 15-7 to 4.6V, and adjust the output end of the eighth voltage-regulated power supply and enameled wire system 15-8 to 4.7V. Use 502 glue to stick the copper enameled wires with insulation layers in the first voltage regulating power supply and enameled wire system 15-1 to the eighth voltage regulating power supply and enameled wire system 15-8 to the outer wall of the test pipe 17 at intervals of 30 cm and connect the voltage signals at both ends of the adjustable DC power supply 19 to the collection box.

[0061] Reference Figure 1 The operating steps of a CO2 pipeline fracture propagation and decompression wave detection test system and its working method according to the present invention are as follows:

[0062] a: Close the sixth manual valve 4-6, open the fifth manual valve 4-5, the fourth manual valve 4-4, and the first manual valve 4-1 in sequence, discharge the gaseous CO2 in the Dewar tank into the experimental main pipeline 7, and the scavenging operation will eventually reduce the temperature of the main pipeline to minus 15°C, and close the fifth manual valve 4-5, the first manual valve 4-1, the fourth manual valve 4-4, in sequence.

[0063] b: Record the initial display value of digital weighing scale 1, open the third manual valve 4-3 and the second manual valve 4-2 in sequence, turn on the control power of plunger pump 3, and inject the liquid CO2 in Dewar jar 2 into main pipeline 7 through plunger pump 3. Based on the phase behavior experiment to be conducted, control the mass of CO2 injected into the experimental main pipeline by the plunger pump, and fill the required plunger according to the display value of digital weighing scale 1. Sequentially close the power of plunger pump 3, the second manual valve 4-2, and the third manual valve 4-3 to complete the liquid CO2 plunger operation.

[0064] c: Set the heating temperature of the rubber heating belt 5 to control the temperature of the CO2 injected into the experimental main pipeline 7. As the temperature of the liquid CO2 rises, the pressure will also increase. When the pressure in the pipe reaches near the theoretical failure pressure value of the defective test pipeline 17, turn off the rubber heating belt 5 and turn on the data acquisition system 13.

[0065] d: When the pressure in the experimental main pipeline 7 exceeds the theoretical failure pressure of the defective test pipeline 17, CO2 is ejected from the prefabricated defect 16. The instantaneous decompression at the jet port causes the CO2 near the crack to form a boiling liquid, which expands into steam and explodes, driving the crack to extend toward both sides of the prefabricated defect 16. Simultaneously, a decompression wave forms at the prefabricated defect 16 and propagates toward both sides of the crack.

[0066] e) As the crack expands due to the pressure within the test tube, it expands and ruptures, breaking the enameled wires in the first through eighth voltage-regulated power supply and enameled wire systems 15-1 through 15-8, which are fixed to the outer tube wall. For example, as the crack expands to the right, the fifth voltage-regulated power supply and enameled wire system 15-5, the sixth voltage-regulated power supply and enameled wire system 15-6, the seventh voltage-regulated power supply and enameled wire system 15-7, and the eighth voltage-regulated power supply and enameled wire system 15-8 are successively broken. The data acquisition system 13 records the voltage values collected from both sides of the fifth through eighth voltage-regulated power supply and enameled wire systems 15-5 through 15-8, and calculates the crack growth rate in the test tube based on the time corresponding to the voltage drop.

[0067] f: The data acquisition system 13 records the CO2 pressure change values inside the experimental main pipeline 7 and the test pipeline 17 when the crack expands, measured by the first high-frequency pressure sensor 9-1 to the sixth high-frequency pressure sensor 9-6, and the CO2 temperature change values inside the experimental main pipeline 7 and the test pipeline 17 when the crack expands, measured by the first T-type armored thermocouple 10-1 to the sixth T-type armored thermocouple 10-6.

[0068] g: The alumina glass transparent kettle 11 can be observed by human eyes or recorded by a high-speed camera on the phase change of CO2 in the main experimental pipe 7 after the test tube 17 is broken.

Claims

1. A system for measuring the propagation velocity of CO2 pipeline fracture propagation and decompression wave in the pipeline, characterized by: The measuring system includes a digital display weighing scale (1), a CO2 dewar cylinder (2), a plunger pump (3), a manual valve, a rubber heating belt (5), an experimental main pipeline (7), a pointer pressure gauge (8), a high-frequency pressure sensor, a T-type armored thermocouple, a phase change observation kettle (11), a data acquisition box (12), a data acquisition system (13), a first crack stop ring (14-1), a second crack stop ring (14-2), a voltage regulating power supply and enameled wire system (15), a prefabricated defect (16), a test pipeline (17), an indicator light (18), an adjustable DC power supply (19) and a copper enameled wire (20); The test pipe (17) is connected to the rear of the experimental main pipe (7) through a flange; The phase change observation kettle (11) is installed in the middle of the experimental main pipeline (7) to observe the phase change of CO2 in the pipeline; The high-frequency pressure sensor and the T-type armored thermocouple need to be installed in pairs on the test pipe (17) and the experimental main pipe (7); The CO2 dewar cylinder (2) provides a gas source for the pipeline fracture experiment, which is injected into the experimental main pipeline (7) through the plunger pump (3). The CO2 in the pipeline is heated by the rubber heating belt (5) to control the CO2 phase state, and the heat-insulating rubber and plastic reduce the heat convection effect between the pipeline and the surrounding environment; the high-frequency pressure sensor provided on the experimental main pipeline (7) and the test pipeline (17) is used to measure the CO2 pressure change value in the pipeline; the T-type armored thermocouple installed on the experimental main pipeline (7) and the test pipeline (17) is used to measure the CO2 temperature change value in the pipeline; the voltage regulating power supply and enameled wire system (15) are fixed at fixed intervals in the circumferential direction of the test pipeline (17) to test the crack propagation speed after the pipeline (17) is fractured; the data acquisition system (13) is used to record the acquisition value of the high-frequency pressure sensor, the measurement value of the T-type armored thermocouple, and the fracture time of adjacent enameled wires; A digital weighing scale (1) is placed under the CO2 dewar cylinder (2) to record the weight of CO2 filled into the pipeline; The data acquisition system (13) is connected to the data acquisition box (12), and the data acquisition box (12) is respectively connected to the high-frequency pressure sensor, the T-type armored thermocouple, the voltage regulating power supply and the enameled wire system (15); The first crack arresting ring (14-1) and the second crack arresting ring (14-2) are respectively installed at equal distances from both ends of the test pipe (17) to verify whether the developed crack arresting device can achieve crack arresting; A pointer pressure gauge (8) is installed on the experimental main pipeline (7); The prefabricated defect (16) is arranged in the middle of the test pipe (17); The number of the voltage regulating power supply and enameled wire systems (15) is an even number and is symmetrically arranged with the prefabricated defect (16) as the center; each voltage regulating power supply and enameled wire system (15) includes an indicator light (18), an adjustable DC power supply (19) and a copper enameled wire (20), the indicator light (18) and the adjustable DC power supply (19) are connected through the copper enameled wire (20) to form a closed loop path, and the indicator light (18) is used to identify whether the circuit has formed a path.

2. A CO2 pipeline fracture propagation and decompression wave propagation velocity measurement system according to claim 1, characterized in that: The phase change observation kettle (11) comprises a mother flange (11-1), a sub-flange (11-2), a hexagon socket bolt (11-3), a cover plate (11-4), a transparent glass (11-5), a forging (11-6) and a polytetrafluoroethylene seal (11-7). The forging (11-6) has two opposite surfaces on the left and right sides that are connected to the experimental main pipeline (7) or the test pipeline (17) through the sub-flange (11-2) or the mother flange (11-1). The sub-flange (11-2) or the mother flange (11-1) is connected to the experimental main pipeline (7) or the test pipeline (17). The test pipes (17) are connected by welding, and the mother flange (11-1) is sealed with the sub-flange (11-2) by bolts and nuts; the front and rear opposite surfaces of the forging (11-6) are connected and used for installing transparent glass (11-5) and polytetrafluoroethylene seal (11-7); the transparent glass (11-5) is embedded in the forging (11-6), and the transparent glass (11-5) is connected to the forging (11-6) by a cover plate (11-4) and a hexagon socket bolt (11-3); the phase change observation kettle (11) as a whole can withstand a pressure of more than 20 MPa.

3. The system for measuring the fracture propagation and decompression wave propagation velocity of a CO2 pipeline according to claim 1, characterized in that: The rubber-plastic insulation layer (6) is wrapped around the outer wall of the experimental main pipeline (7) through a clamp. The outer wall of the rubber-plastic insulation layer (6) is wrapped with aluminum foil. The rubber-plastic insulation layer (6) and the aluminum foil can reduce the convective heat exchange intensity between the surrounding environment and the pipeline.

4. A CO2 pipeline fracture propagation and decompression wave propagation velocity measurement system according to claim 1, characterized in that: The angle between the high-frequency pressure sensor installed on the experimental main pipeline (7) and the straight line of the circle center and the vertical distance is 0°~15°; the angle between the T-type armored thermocouple installed on the experimental main pipeline (7) and the straight line of the circle center and the vertical distance is 90°~105°.

5. The system for measuring the fracture propagation and decompression wave propagation velocity of a CO2 pipeline according to claim 1, characterized in that: The angle between the vertical distance between the prefabricated defect and the center of the circle is 0°~5°; the angle between the vertical distance between the high-frequency pressure sensor installed on the test pipe (17) and the center of the circle is 0°~95°; the angle between the vertical distance between the straight line and the center of the circle installed on the T-type armored thermocouple installed on the experimental main pipe (7) and the center of the circle is 315°~320°.

6. The method for using the measurement system according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Process a test pipe (17) with a prefabricated defect (16), connect an adjustable DC power supply (19) with different voltage values to both sides of the copper enameled wire (20), and connect an indicator light (18) in series to form a closed loop; fix the voltage regulating power supply and enameled wire system in the circumferential direction of the test pipe (17); open the manual valve to discharge the gas phase CO2 in the CO2 Dewar cylinder (2) into the experimental main pipe (7); the scavenging operation finally reduces the temperature of the experimental main pipe (7) to below -15°C, and close the manual valve; S2: Start the data acquisition system (13), record the initial display value of the digital display weighing scale (1), open the manual valve and the plunger pump (3) in sequence, and inject the liquid CO2 in the CO2 dewar cylinder (2) into the experimental main pipeline (7) through the plunger pump (3); according to the phase experiment to be carried out, control the mass of CO2 injected into the experimental main pipeline (7) by the plunger pump (3), and fill the required filling amount according to the display value of the digital display weighing scale (1); close the plunger pump (3) and the manual valve in sequence to complete the liquid CO2 filling work; S3: Set the heating temperature of the rubber heating belt (5) to control the temperature of the CO2 injected into the main experimental pipe (7). When the temperature of the liquid CO2 rises, the pressure will also rise. When the pressure in the pipe reaches the theoretical failure pressure value of the test pipe (17) containing defects, turn off the rubber heating belt (5); S4: When the pressure in the experimental main pipe (7) is higher than the theoretical failure pressure of the test pipe (17) containing the defect, CO2 will be ejected from the prefabricated defect (16). The instantaneous decompression of the ejection port causes the CO2 near the crack mouth to form a boiling liquid, which expands and explodes to drive the crack to expand to both sides of the prefabricated defect (16). At the same time, a decompression wave is formed at the prefabricated defect (16) and propagates to both sides of the crack. S5: When the crack expands, it expands due to the pressure inside the test pipe and cracks, breaking the enameled wires in the voltage regulating power supply and enameled wire system (15) fixed to the outer pipe wall; when the crack expands to the right, the voltage regulating power supply and enameled wire system on the right side are broken in sequence; the data acquisition system (13) records the voltage values collected on both sides of the voltage regulating power supply and enameled wire system on the right side, and calculates the speed of crack expansion in the test pipe based on the time corresponding to the decrease in the voltage value; S6: The data acquisition system (13) records the CO2 pressure change value in the experimental main pipe (7) and the test pipe (17) when the crack propagates as measured by the high-frequency pressure sensor, and the CO2 temperature change value in the experimental main pipe (7) and the test pipe (17) when the crack propagates as measured by the T-type armored thermocouple; S7: The phase change observation kettle (11) can be used to observe with the human eye or record with a high-speed camera the phase change pattern of CO2 in the experimental main pipeline (7) after the test pipeline (17) is broken.

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