An online monitoring device and method for minor leakage of a safety valve

Abstract

The present invention discloses an online monitoring device and method for detecting minor leaks in safety valves. In the online monitoring device, a variable reluctance generator is placed within a detection pipe. An electronic control device is mounted on the detection pipe and connected to the variable reluctance generator via a wire. A float flowmeter is connected to the detection pipe via a threaded hole, and the float flowmeter is connected to an automatic opening and closing device. When a high-flow gas flows through the detection pipe, the float flowmeter controls the opening of the automatic opening and closing device by moving the float upward. When the safety valve is released, the electronic control device sends an electrical signal to a second coil to control the closing of the automatic opening and closing device. At this time, the gas flow rate is calculated from the induced electromotive force of the coil. When a low-flow gas flows through the detection pipe, the gas flow rate is calculated from the displacement of the float in the float flowmeter. This invention achieves flow measurement under both safety valve failure leakage and overpressure relief conditions without affecting the normal release of the safety valve, achieving high detection efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of safety valve leakage monitoring, and in particular to an online monitoring device and method for minor leakage of a safety valve. Background Art

[0002] Hydrogen energy has garnered widespread attention due to its high energy efficiency, widespread availability, and pollution-free nature. However, while hydrogen boasts advantages such as ease of availability and zero carbon emissions, it also suffers from significant drawbacks that hinder its storage and transportation, including a wide flammability range, low ignition energy, and difficulty in liquefaction. With the gradual maturation of high-pressure hydrogen storage technology, high-pressure gaseous hydrogen storage is currently the most widely used method of hydrogen storage due to its advanced technology and rapid charging and discharging rates. The large-scale use of hydrogen energy aligns with my country's commitment to diversified energy supply-side reform and the goal of building a clean, low-carbon, safe, and efficient energy system. Hydrogen, with its wide flammability range and low ignition energy, is highly susceptible to fire and explosion accidents, particularly during the storage and transportation of high-pressure hydrogen, where the increased uncertainty presents a significant risk of serious accidents. As overpressure protection devices for equipment and pipelines, safety valves are widely used in hydrogen storage and transportation systems, playing a crucial role in ensuring personnel safety and ensuring the smooth operation of production. During operation, safety valves reliably open and release pressure when internal pressure exceeds the set pressure and automatically close when internal pressure falls below it. The sealing performance of a valve refers to the ability of each sealing part within the valve to prevent the leakage of the medium. It is one of the most important technical performance indicators of the valve. However, in actual industrial equipment applications, nearly 20% of valves have leakage problems, which can be roughly divided into the following two types of leakage: (1) When the internal pressure of the equipment approaches the set pressure, the force on the safety valve sealing surface decreases, resulting in gas leakage; (2) The sealing surface suffers from wear, foreign matter damage, and other problems during use, resulting in sealing surface failure and leakage. According to statistics, nearly 40% of explosion accidents in the petrochemical industry are caused by valve leakage; and in the medium transmission equipment in the petrochemical industry, the uncontrolled release of volatile organic compounds caused by valve leakage reaches 60%.

[0003] Current valve leak detection methods include: negative pressure wave detection, bubble detection, ultrasonic leak detection, infrared temperature measurement, and acoustic emission testing. Negative pressure wave detection has poor anti-interference capabilities and is easily affected by pressure fluctuations, making it inadequate for detecting small leak rates. The bubble method relies on visual observation to record the number of leaking bubbles, which is time-consuming and labor-intensive, prone to errors, and even more time-consuming for weak leaks. Ultrasonic testing technology is suitable for applications where gas flows through a leak, creating a turbulent flow field. As an active detection method, it is not suitable for real-time detection. Acoustic emission leak detection is a widely used dynamic nondestructive testing method that can monitor the entire object being tested online. However, due to the high noise environment, acoustic emission leak detection results are significantly affected by noise. Most current detection technologies require specialized personnel and equipment, have a limited detection range, require a long time, have low detection accuracy, and some may even damage the valve. Therefore, they cannot meet the needs of on-site detection of small valve leaks. Summary of the Invention

[0004] Purpose of the invention: The purpose of the present invention is to provide an online monitoring device and method for minor leakage of a safety valve, which can realize flow measurement of two working conditions, namely safety valve failure leakage and overpressure relief, without affecting the normal relief of the safety valve, automatically change the detection method, and improve the detection accuracy of minor leakage.

[0005] Technical solution: An online monitoring device for minor leakage of a safety valve, including a detection pipeline, a variable reluctance power generation device, an electronic control device, a float flowmeter, and an automatic opening and closing device;

[0006] The variable reluctance type generator is placed in the detection pipe, the electric control device is arranged on the detection pipe and connected to the variable reluctance type generator through a wire, the float flowmeter is connected to the detection pipe through a threaded hole, and the float flowmeter is connected to the automatic opening and closing device;

[0007] When a large amount of air flows through the detection pipe, the airflow drives the rotor to rotate, the variable reluctance generator works, and the float flowmeter controls the opening of the automatic opening and closing device by moving the float upward. When the safety valve is released, the electronic control device sends an electrical signal to the second coil to control the closing of the automatic opening and closing device. At this time, the electronic control device obtains the induced electromotive force of the coil and calculates the gas flow rate.

[0008] When a small flow of air passes through the detection pipe, the variable reluctance generator does not work, and the float moves upward under the action of the gas. At this time, the displacement of the float flowmeter is obtained by the electronic control device, and the gas flow is calculated.

[0009] Furthermore, the detection pipe includes a conversion joint and a detection pipe housing. The detection device housing is connected to the conversion joint through a thread, and the conversion joint can be connected to safety valves of different calibers; the detection device housing is made of magnetic conductive material and has a countersunk hole and a threaded through hole. The electronic control device is placed in the countersunk hole, and the float flowmeter is installed in the threaded through hole.

[0010] Furthermore, the variable reluctance power generation device includes a deflector, a rotor, a shaft, a bearing, a magnet, a first coil, a blade and a sleeve. The deflector is connected to the shaft through a bearing, the rotor is fixed on the shaft and positioned by the sleeve, the first coil is wound around the magnet and placed in the countersunk hole, and the deflector has blades arranged along the circumference; when the airflow passes through the deflector, it drives the rotor to rotate.

[0011] Furthermore, the electronic control device includes an electronic control device body, a first output interface, a second output interface, a first input interface and a second input interface; the first input interface is connected to the first coil, the second input interface is connected to the displacement sensor, the electronic control device body includes an electronic control processing module, an energy storage module and a display module, the electronic control processing module includes a frequency module, a rectifier module and a processing module; the first output interface is connected to the display module, the frequency module, the rectifier module and the processing module, and the second output interface is connected to the second coil.

[0012] Furthermore, the float flowmeter includes an upper end cover, a second shell, a displacement sensor, and a float, wherein a through hole is opened in the middle of the upper end cover and is provided on the second shell, and the displacement sensor lead-out terminal is connected to the second input interface through a wire; a hole is opened on the side of the second shell, and the hole is used to install the slider guide rail in the automatic opening and closing device; the float is a cylinder with a hole in the middle and equal upper and lower surface areas, which is mounted on the displacement sensor guide rail and can float up and down; the internal flow channel of the second shell has a certain cone angle, and the top of the cone angle is provided at the connection end of the detection pipeline.

[0013] Furthermore, the automatic opening and closing device includes a slider, a slider guide, a first spring, a guide rail rear cover, a support frame, a pipe rear cover, a second spring, a connecting plate, a connecting shaft, a terminal and a second coil, wherein the slider is made of magnetic material and is arranged on the slider guide, one end of the second spring is connected to the lifting ear on the slider, and the other end is connected to the lifting ear on the pipe rear cover, the slider guide is inserted into the hole, and the second coil on the guide rail rear cover is connected to the second output interface; one end of the first spring is fixed to the guide rail rear cover, and the other end is fixed to the rear end of the slider; the slider, the slider guide and the first spring are all arranged on the support frame, the support frame is bolted to the connecting plate, and the connecting plate is fixedly connected to the detection device housing; the pipe rear cover is connected to the connecting plate via a connecting shaft, and the pipe rear cover can rotate around the connecting shaft;

[0014] When the flow rate increases slowly, the float rises and the flow rate increases to the critical discharge flow rate Q sWhen the float is in the air, the upper surface of the float touches the hook-shaped structure at the front end of the slider, and the connection between the slider and the inner surface of the second shell is disconnected, triggering the rebound mechanism. Under the action of the restoring force of the first spring, the slider moves to the right, driving the second spring to move, and the rear cover of the pipeline opens;

[0015] When the safety valve is released, the flow rate drops to the critical discharge flow Q s , the rear cover of the pipe needs to be closed. At this time, the electronic control device sends an electrical signal to the terminal block, and the second coil is energized to generate a magnetic field; the slider moves away from the rear cover of the guide rail under the action of the magnetic force, pulling the first spring and the second spring, and the rear cover of the pipe slowly closes; when the front end of the slider is reconnected with the inner surface of the second shell, it returns to the initial state.

[0016] A method for implementing any of the above-mentioned online monitoring devices, including a method for detecting small flow rates of safety valve leakage, a variable reluctance flow detection and power generation method;

[0017] When a small leak occurs, the safety valve leakage small flow detection method is used, and the float flowmeter measures the small flow generated. The implementation process is as follows:

[0018] When gas enters the test pipe through the conversion joint, it is guided by the leaf, driving the rotor to rotate at an angular velocity ω. At the same time, it enters the float flowmeter through the threaded hole on the detection device housing. Under the action of the gas, the float moves upward. When the flow rate stabilizes, the float hovers at a certain position. Let the displacement at this time be x. The force on the float is as follows:

[0019] mg=Δp·A

[0020] Where m is the mass of the float, Δp is the pressure difference between the upper and lower surfaces of the float, and A is the projected area of ​​the float along the displacement direction;

[0021] According to the orifice flow formula:

[0022]

[0023] A0=f(x)

[0024] Among them, C d is the flow coefficient, ρ is the gas density; A0 is the flow area at the center of gravity of the float;

[0025] Then the gas flow rate q 1流 The formula is:

[0026]

[0027] According to the above formula, the displacement x of the float is obtained by the displacement sensor and transmitted to the electronic control device to obtain the flow rate passing through the float flowmeter;

[0028] When the leakage flow is large, the rotor rotates and the variable reluctance flow detection and power generation method is used to measure the generated flow. The implementation process is as follows:

[0029] When the gas drives the rotor to rotate at an angular velocity ω, the first coil generates an induced electromotive force E:

[0030] E=ψ(ω)

[0031] Therefore, the frequency of the induced electromotive force E is obtained through the frequency module of the electronic control device, and the current rotor speed ω = ψ -1 (E); The relationship between the rotor angular velocity ω and the flow rate q2 is as follows:

[0032]

[0033] Where r is the average radius of the rotor blade, α is the angle between the rotor blade and the axis, c is a constant, and A is the flow cross-sectional area of ​​the rotor;

[0034] Then the gas flow rate q 2流 for:

[0035]

[0036] According to the above formula, the induced electromotive force ψ(ω) generated by the first coil is transmitted to the electronic control device to obtain the flow rate passing through the float flowmeter.

[0037] Compared with the prior art, the present invention has the following significant effects:

[0038] 1. The online monitoring device of the present invention is designed with an airflow discharge channel for normal discharge of the safety valve and a monitoring channel for minor leakage when the safety valve is closed. This achieves flow measurement under both safety valve fault leakage and overpressure relief conditions without affecting the normal discharge of the safety valve, achieving high detection efficiency.

[0039] 2. The online monitoring device of the present invention is designed with a discharge channel opening and closing mechanism based on spring energy storage and electromagnetic actuation, which automatically opens the discharge channel when the valve is discharging and actively closes the discharge channel when the valve is closed;

[0040] 3. The online monitoring device of the present invention is designed with a variable reluctance power generation mechanism to realize power generation and storage when the gas is normally discharged. This allows the device to be independent of external power supply and achieve self-sufficiency in electricity. It does not require an external power supply and is suitable for safety valve maintenance scenarios in harsh field environments. It can improve maintenance efficiency, enhance the stability of the hydrogen storage system, and expand its application scenarios.

[0041] 4. The online monitoring method of the present invention has a good gathering effect on the leaked gas through the small leakage monitoring channel. Under the premise of no human intervention and no influence on the normal operation of the safety valve, the detection method is automatically changed, thereby improving the detection accuracy of small leaks. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 (a) is a partial cross-sectional schematic diagram of the main structure of the present invention;

[0043] (b) is a schematic diagram of the present invention.

[0044] Figure 2 This is a schematic diagram of the detection pipeline structure of the present invention;

[0045] Figure 3 (a) is a cross-sectional view of the variable reluctance power generation device of the present invention;

[0046] (b) is a schematic diagram of the overall structure of the variable reluctance power generation device of the present invention;

[0047] (c) is a schematic diagram of the magnet and coil in the variable reluctance generator;

[0048] Figure 4 It is a structural schematic diagram of the electronic control device of the present invention;

[0049] Figure 5 It is a structural schematic diagram of the float flowmeter of the present invention;

[0050] Figure 6 (a) is a schematic diagram of the overall structure of the automatic opening and closing device of the present invention;

[0051] (b) Figure 6 The main view of (a);

[0052] Figure 7 This is a control principle diagram of the electronic control device of the present invention;

[0053] Figure 8 (a) is a schematic diagram of the closed state of the automatic opening and closing device of the present invention;

[0054] (b) is a schematic diagram of the automatic opening and closing device of the present invention in the open state;

[0055] Figure 9 This is a detection flow chart of the present invention. DETAILED DESCRIPTION

[0056] The present invention will be described in further detail below with reference to the accompanying drawings and specific implementations.

[0057] like Figure 1As shown in (a) and (b) of FIG. 1 , an online monitoring device for minor leakage of a safety valve includes a mechanical structure, which includes: a detection pipeline 1, a variable reluctance generator 2, an electronic control device 3, a float flowmeter 4, and an automatic opening and closing device 5.

[0058] like Figure 2 As shown, the detection pipe 1 includes a conversion joint 11 and a detection pipe housing 12. The conversion joint 11 is used to connect safety valves of different calibers to the detection pipe 1. The detection device housing 12 is made of magnetic conductive material and provides a detection flow path. The detection device housing 12 and the conversion joint 11 are connected by threads. The detection device housing 12 has a countersunk hole 13 and a threaded through hole 14. The countersunk hole 13 houses the magnet 25 and the electronic control device body 31. The threaded through hole 14 is connected to the float flowmeter 4.

[0059] like Figure 3 As shown in (a), (b), and (c) of FIG. 1 , the variable reluctance generator 2 comprises: a deflector 21, a rotor 22, a shaft 23, a bearing 24, a magnet 25, a first coil 26, a sprocket 27, and a sleeve 28. The rotor 22 and deflector 21 are connected to the shaft 23 via the bearing 24. The sleeve 28 serves as a positioning mechanism. When air flows through the deflector 21, it drives the rotor 22 to rotate about the shaft 23. The magnet 25, wound around the first coil 26, is placed in the counterbore 13 of the detection pipe 1. Sprockets 27 are arranged circumferentially around the deflector 21; the rotor 22 is made of a magnetically conductive material.

[0060] like Figure 4 As shown, the electronic control device 3 includes an electronic control device body 31, a first output interface 32, a second output interface 33, a first input interface 34, and a second input interface 35. The electronic control device body 31 includes an electronic control processing module, an energy storage module, and a display module. The first input interface 34 is connected to the first coil 26, and the electrical signal generated by the first coil 26 is input into the electronic control device body 31. The second input interface 35 is connected to the displacement sensor 43, which inputs the displacement of the float 44 into the electronic control device body 31. The first output interface 32 is connected to other electrical components of the device to provide energy, and the second output interface 33 is connected to the second coil 511 to provide electrical signals.

[0061] The electronic control processing module includes a frequency module, a rectifier module, and a processing module. The frequency module is responsible for obtaining the frequency of the induced electromotive force output by the first coil 26 and transmitting this frequency to the processing module. The rectifier module converts the unstable induced electromotive force output by the first coil 26 into a voltage signal with a stable frequency and amplitude, and then outputs this stable voltage signal to the energy storage module. The energy storage module stores the electrical energy generated during discharge to maintain the operation of the entire device. The display module displays the flow rate measured at any time.

[0062] like Figure 5As shown, the float flowmeter 4 comprises an upper end cap 41, a second housing 42, a displacement sensor 43, and a float 44. The upper end cap 41 has a through hole and is mounted on the housing 42. The lead-out terminal of the displacement sensor 43 is connected to the second input interface 35 via a wire. The second housing 42 has a hole 45, which connects to the slider guide 52 and is open to the atmosphere. This hole 45 serves as a gas vent when the safety valve leaks a small amount of gas. The float 44 is a cylinder with a central hole and equal upper and lower surface areas. It fits on the displacement sensor guide and can float up and down. The flow channel inside the second housing 42 forms a tapered angle, with the top of the cone located at the connection end of the detection pipeline 1. When the safety valve leaks a small amount, the leaked gas is discharged through the hole 45, and the automatic opening and closing device 5 remains closed.

[0063] like Figure 6 As shown in (a) and (b), the automatic opening and closing device 5 includes: a slider 51, a slider guide rail 52, a first spring 53, a guide rail back cover 54, a support frame 55, a pipe back cover 56, a second spring 57, a connecting plate 58, a connecting shaft 59, a terminal 510, and a second coil 511. Among them, the slider 51 is made of magnetic material and is arranged on the slider guide rail 52. The ears on both sides of the slider 51 are connected to the ears on both sides of the pipe back cover 56 through the second spring 57. One end of the first spring 53 is fixed on the guide rail back cover 54, and the other end is fixed to the rear end of the slider 51. The slider guide rail 52 is inserted into the hole 45 of the second shell 42 of the float flowmeter. The second coil 511 on the guide rail back cover 54 is wound with a wire and connected to the second output interface 33. The slider 51, the slider guide rail 52 and the first spring 53 are arranged on the support frame 55. The support frame 55 is bolted to the connecting plate 58. The connecting plate 58 is welded to the detection device housing 12. The pipe back cover 56 is connected to the connecting plate 58 through the connecting shaft 59. The pipe back cover 56 can rotate around the connecting shaft 59 to realize the opening and closing of the detection device.

[0064] An online monitoring method for minor leakage of a safety valve includes a method for detecting minor flow of leakage of a safety valve, a method for detecting and generating power by a variable magnetic resistance flow, and a method for automatically opening and closing a rear cover. The control principle diagram of the electronic control device is shown in FIG. Figure 7 shown.

[0065] The principle of the method for detecting low-flow leakage in a hydrogen storage safety valve is as follows: Under normal circumstances, the pipe rear cover 56 is closed. Gas enters the test pipe through the adapter 11, passes through the guide of the leaf 27, and drives the rotor 22 to rotate at an angular velocity ω. Simultaneously, it enters the float flowmeter 4 through the threaded through-hole 14 in the detection device housing 12. The gas acts on the float 44, causing it to move upward. When the flow rate stabilizes, the float 44 hovers at a certain position. Assume that the displacement at this time is x. The force on the float 44 is as follows:

[0066] mg=Δp·A

[0067] Wherein, m is the mass of the float 44, Δp is the pressure difference between the upper and lower surfaces of the float 44, and A is the projected area of ​​the float 44 along the displacement direction;

[0068] According to the orifice flow formula:

[0069]

[0070] Among them, C d is the flow coefficient, ρ is the gas density;

[0071] A0 is the gas flow area A0 = f(x) is a function of the displacement x. Since the float flowmeter 4 measures a small flow rate and the float 44 is small, A0 is the flow area at the center of gravity of the float 44.

[0072] Then the gas flow rate q 1流 The formula is:

[0073]

[0074] The displacement x of the float is obtained by the displacement sensor 43 and transmitted to the electronic control device 3, so that the flow rate passing through the float flowmeter can be obtained.

[0075] The principle of the variable reluctance flow detection and power generation method is as follows: the gas drives the rotor 22 to rotate at an angular velocity ω, and the first coil 26 is wound around the magnet 25. Since the rotation of the rotor 22 changes the air gap of the magnetic circuit, the magnetic resistance in the magnetic circuit changes. The magnetic potential of the entire magnetic field is constant, which changes the magnetic flux in the magnetic circuit, so that the coil generates an induced electromotive force E = ψ(ω). Therefore, by obtaining the frequency of the induced electromotive force E through the frequency module 34 of the electronic control device 3, the current rotor 22 speed ω = ψ -1 (E).

[0076] The relationship between the rotor angular velocity ω and the flow rate q2 is as follows:

[0077]

[0078] Wherein, r is the average radius of the blades of the rotor 22 , α is the angle between the blades of the rotor 22 and the axis, c is a constant, and A is the flow cross-sectional area of ​​the rotor 22 .

[0079] Then the gas flow rate q 2流 for:

[0080]

[0081] However, it should be noted that due to the uneven rotor speed, the frequency and magnitude of the induced electromotive force are unstable. Therefore, a rectifier module 35 is added to the electronic control device 3 to convert this uneven, weak induced electromotive force E into a stable voltage signal, which is stored in the energy storage module 38 and provides power for the entire detection device. This flow measurement method is suitable for larger flow rates because the flow rate is small during a leak and the rotor 22 does not rotate. In the case of a small leak, the small flow rate generated is measured by the float flowmeter 4. This method achieves classified detection of different flow rates.

[0082] The principle of the automatic opening and closing method of the rear cover is as follows: Under normal circumstances, the pipeline rear cover 56 is closed, the slider 51 is located in the hole 45 of the second housing 42 of the float flowmeter, and the front end of the slider 51 is connected to the inner surface of the float flowmeter housing 42 through a hook structure. One end of the first spring 53 is fixed to the guide rail rear cover 54, and the other end is fixed to the rear end of the slider 51. At this time, the first spring 53 is in a stretched state, and one end of the second spring 57 is connected to the ear on the slider 51, and the other end is connected to the ear on the pipeline rear cover 56. The pipeline rear cover 54 is subjected to the tension of the second spring 57 and fits tightly against the detection device housing 12 to play a sealing role. Figure 8 As shown in (a) in . Figure 9 As shown, when the flow rate increases slowly, the float rises and the flow rate increases to the critical discharge flow rate Q s When the float 44 is in contact with the hook structure at the front end of the slider 51, the connection between the slider 51 and the inner surface of the second housing 42 is disconnected, triggering the rebound mechanism. Under the action of the restoring force of the first spring 53, the slider 51 moves to the right, driving the second spring 57 to move, and the pipe rear cover 56 opens. Figure 8 As shown in (b) in the figure. When the safety valve is released, the flow rate drops to the critical discharge flow rate Q s When the pipe rear cover 56 needs to be closed, the electronic control device 3 sends an electrical signal to the terminal 510 on the guide rail rear cover 54, energizing the second coil 511 and generating a magnetic field. The slider 51, acting under the magnetic force, moves away from the guide rail rear cover 56, pulling the first spring 53 and the second spring 57, slowly closing the pipe rear cover 56. When the front end of the slider 51 reconnects with the inner surface of the second housing 42, the pipe rear cover 56 returns to its initial state. This entire process requires no human intervention; the device itself generates the corresponding actions, achieving automatic flow rate detection.

[0083] In this way, the classification and automatic detection of the flow rates of the hydrogen storage safety valve in two states, leakage and discharge, can be achieved, and power generation and storage of electrical energy can be achieved during operation.

Claims

1. An online monitoring device for minor leakage of a safety valve, characterized in that: It includes a detection pipeline (1), a variable reluctance type power generation device (2), an electric control device (3), a float flow meter (4), and an automatic opening and closing device (5); The variable reluctance type power generation device (2) is placed in the detection pipe (1), the electric control device (3) is arranged on the detection pipe (1) and is connected to the variable reluctance type power generation device (2) via a wire, the float flow meter (4) is connected to the detection pipe (1) via a threaded through hole; the float flow meter (4) is connected to the automatic opening and closing device (5); When a large flow of gas passes through the detection pipe (1), the variable reluctance type generator (2) operates, and the float flowmeter (4) controls the opening of the automatic opening and closing device (5) by moving the float (44) upward; when the safety valve is discharged, the electric control device (3) sends an electric signal to the second coil (511) to control the closing of the automatic opening and closing device (5); in this process, the induced electromotive force of the coil is obtained by the electric control device (3), and the gas flow rate is calculated; When a small flow rate of air passes through the detection pipe (1), the variable reluctance type power generation device (2) does not work, and the float (44) moves upward under the action of the gas; at this time, the displacement of the float in the float flowmeter (4) is obtained by the electronic control device (3), and the gas flow rate is calculated.

2. The online monitoring device for minor leakage of a safety valve according to claim 1 is characterized in that: The detection pipe (1) comprises a conversion joint (11) and a detection pipe housing (12), wherein the detection pipe housing (12) is connected to the conversion joint (11) via a threaded connection, and the conversion joint (11) can be connected to safety valves of different calibers; the detection pipe housing (12) is made of a magnetic conductive material and has a countersunk hole (13) and a threaded through hole (14); the electric control device (3) is placed in the countersunk hole (13), and the float flowmeter (4) is installed in the threaded through hole (14).

3. The online monitoring device for minor leakage of a safety valve according to claim 2 is characterized in that: The variable reluctance power generation device (2) comprises a deflector (21), a rotor (22), a shaft (23), a bearing (24), a magnet (25), a first coil (26), a cascade (27) and a sleeve (28). The deflector (21) is connected to the shaft (23) via the bearing (24). The rotor (22) is fixed on the shaft (23) and positioned via the sleeve (28). The first coil (26) is wound around the magnet (25) and is placed in the countersunk hole (13). The deflector (21) is provided with cascades (27) arranged circumferentially. When air flows through the deflector (21), the rotor (22) is driven to rotate.

4. The online monitoring device for minor leakage of a safety valve according to claim 3 is characterized in that: The electronic control device (3) comprises an electronic control device body (31), a first output interface (32), a second output interface (33), a first input interface (34), and a second input interface (35); the first input interface (34) is connected to the first coil (26), the second input interface (35) is connected to the displacement sensor (43), the electronic control device body (31) comprises an electronic control processing module, an energy storage module, and a display module, the electronic control processing module comprises a frequency module, a rectifier module, and a processing module; the first output interface (32) is connected to the display module, the frequency module, the rectifier module, and the processing module, and the second output interface (33) is connected to the second coil (511).

5. The online monitoring device for minor leakage of a safety valve according to claim 4, characterized in that: The float flowmeter (4) comprises an upper end cover (41), a second housing (42), a displacement sensor (43), and a float (44), wherein the upper end cover (41) has a through hole in the middle and is arranged on the second housing (42), and the displacement sensor (43) leads to a wiring terminal connected to the second input interface (35) through a wire; an opening (45) is provided on the side of the second housing (42), and the opening (45) is used to install a slider guide rail (52) in the automatic opening and closing device (5) and is connected to the atmosphere; the float (44) is a cylinder with a central opening and equal upper and lower surface areas, and is sleeved on the displacement sensor guide rail and can float up and down; the internal flow channel of the second housing (42) has a certain cone angle, and the top of the cone angle is arranged at the connection end of the detection pipeline (1).

6. The online monitoring device for minor leakage of a safety valve according to claim 5, characterized in that: The automatic opening and closing device (5) comprises a slider (51), a slider guide rail (52), a first spring (53), a guide rail rear cover (54), a support frame (55), a pipe rear cover (56), a second spring (57), a connecting plate (58), a connecting shaft (59), a terminal (510) and a second coil (511), wherein the slider (51) is made of magnetic material and is arranged on the slider guide rail (52), one end of the second spring (57) is connected to the lug on the slider (51) and the other end is connected to the lug on the pipe rear cover (56), and the slider guide rail (52) is inserted into the opening (45). , the second coil (511) on the guide rail rear cover (54) is connected to the second output interface (33); one end of the first spring (53) is fixed to the guide rail rear cover (54), and the other end is fixed to the rear end of the slider (51); the slider (51), the slider guide rail (52) and the first spring (53) are all arranged on the support frame (55), the support frame (55) is bolted to the connecting plate (58), and the connecting plate (58) is fixedly connected to the detection pipeline housing (12); the pipeline rear cover (56) is connected to the connecting plate (58) through the connecting shaft (59), and the pipeline rear cover (56) can rotate around the connecting shaft (59); When the flow rate increases slowly, the float rises and the flow rate increases to the critical discharge flow rate Q s When the upper surface of the float (44) touches the hook structure at the front end of the slider (51), the connection between the slider (51) and the inner surface of the second shell (42) is disconnected, triggering the rebound mechanism. Under the action of the restoring force of the first spring (53), the slider (51) moves to the right, driving the second spring (57) to move, and the pipeline rear cover (56) opens; When the safety valve is released, the flow rate drops to the critical discharge flow Q s , the pipe rear cover (56) needs to be closed, at which time the electric control device (3) sends an electric signal to the terminal (510), the second coil (511) is energized, and a magnetic field is generated; the slider (51) is moved in a direction away from the guide rail rear cover (54) by the magnetic force, pulling the first spring (53) and the second spring (57), and the pipe rear cover (56) slowly closes; when the front end of the slider (51) is reconnected with the inner surface of the second shell (42), it returns to the initial state.

7. The method for implementing the online monitoring device according to claim 6, wherein: Including safety valve leakage small flow detection method, variable magnetic resistance flow detection and power generation method; When a small leakage occurs, the safety valve leakage small flow detection method is used, and the small flow generated is measured by the float flowmeter (4); the implementation process is as follows: When gas enters the detection pipe from the conversion joint (11), it is guided by the blade grid (27) and drives the rotor (22) to rotate at an angular velocity ω. At the same time, it enters the float flowmeter (4) through the threaded through hole (14) on the detection pipe housing (12). Under the action of the gas, the float (44) moves upward. When the flow rate is stable, the float (44) hovers at a certain position. Let the displacement at this time be x. Then the force on the float (44) is as follows: ， Where m is the mass of the float, is the pressure difference between the upper and lower surfaces of the float, and A is the projected area of ​​the float along the displacement direction; According to the orifice flow formula: , A0=f (x), Among them, C d is the flow coefficient, ρ is the gas density; A0 is the flow area at the center of gravity of the float; then the gas flow rate q 1流 The formula is: , According to the above formula, the displacement x of the float is obtained by the displacement sensor (43) and transmitted to the electronic control device (3) to obtain the flow rate passing through the float flowmeter; When the leakage flow is large, the rotor (22) rotates, and a variable magnetic resistance flow detection and power generation method is used to measure the generated flow. The implementation process is as follows: when the gas drives the rotor (22) to rotate at an angular velocity ω, the first coil (26) generates an induced electromotive force E: , Thus, the frequency of the induced electromotive force E is obtained through the frequency module of the electronic control device (3), and the current rotor (22) speed is obtained. ; Rotor angular velocity The relationship with flow q2 is as follows: , Among them, r is the average radius of the rotor blade, α is the angle between the rotor blade and the axis, c is a constant, and A is the flow cross-sectional area of ​​the rotor; then the gas flow rate q 2流 for: , According to the above formula, the first coil (26) generates an induced electromotive force The data is transmitted to the electronic control device (3) to obtain the flow rate through the float flowmeter.

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