Sand hole leakage defect simulation test device and oxygen leakage concentration detection method

Abstract

The present invention relates to a simulation test device for sand hole leakage defects and an oxygen leakage concentration detection method. The device includes a mixed gas supply module, a first pressure balance adjustment module, a second pressure balance adjustment module, a sand hole leakage defect simulation module, a ventilation module, and a plurality of gas on-off control structures connecting each module. The sand hole leakage defect simulation module includes a sealed cavity and a sand hole leakage defect housing located inside it, a temperature and pressure measurement unit, a cooling unit, a heating unit, and a capillary unit. The temperature and pressure measurement unit is connected to the outer wall of the top of the housing, the cooling unit is closely attached to the outer wall of the housing, the heating unit is located inside the housing, and the capillary unit extends into the interior from the bottom of the housing and communicates with it. Compared with the prior art, the present invention has the advantages of improving the accuracy of sand hole leakage defect simulation and the accuracy of O2 annual leakage rate detection, etc.

Description

Technical Field

[0001] The invention relates to the field of gas leakage, in particular to a sand hole leakage defect simulation test device and an oxygen leakage concentration detection method. Background Art

[0002] With the proposal of the "dual carbon" goal, power grid companies have gradually adopted environmentally friendly gases as insulation and arc extinguishing media to replace pure SF6 gas. At present, C4F7N / CO2 / O2 mixed gas GIS equipment has been successfully put into operation in practical applications and achieved good operating results. The housing of electrical equipment is generally made of metal. During casting, due to the influence of bubbles, impurities, etc., some parts may be thin. After a long period of corrosion, the air gap channel is opened, forming capillary straight pipe-shaped sand holes. After long-term leakage, the gas density in the electrical equipment decreases significantly, thereby reducing the insulation and arc extinguishing levels of the gas chamber and increasing the probability of latent faults. According to the relevant regulations of the State Grid, the annual leakage rate of electrical equipment cannot exceed 0.5%. Therefore, in view of the problems caused by sand hole gas leakage, gas leakage detection and post-detection repair of electrical equipment are necessary links in daily operation and maintenance.

[0003] Normally, for gas leakage in electrical equipment, referring to the standard GB / T 11023-2018, on-site leak detection mainly adopts the local bandaging method or the buckle cover method. After a certain period of time (24h), the concentration of gas leaking into the closed structure is detected, and the leakage rate of the electrical equipment is obtained by calculation. However, compared with pure SF6 gas, the leakage of C4F7N / CO2 / O2 mixed gas is more complicated. Under ideal conditions, the leakage rate of each component gas in the mixed gas is related to its absolute partial pressure difference. Since the air contains about 21% O2, the three component gases in the C4F7N / CO2 / O2 mixed gas do not leak in equal proportions. The ratio of the O2 leakage rate to the C4F7N / CO2 / O2 mixed gas leakage rate is lower than the mixing ratio, so the mixing ratio will change significantly after long-term leakage. Since the air contains a high concentration of O2, the leaked ppm-level (one part per million by volume) O2 is difficult to measure by a detection instrument. Therefore, the prior art mainly detects the concentration of C4F7N or CO2 in a closed structure, and then directly calculates the leakage rate of the C4F7N / CO2 / O2 mixed gas according to the mixing ratio. The calculated result deviates greatly from the actual value, which may lead to a misjudgment of the leakage state of the electrical equipment, and then cause a more serious power operation accident. In addition, the aforementioned research on gas leakage of electrical equipment has not specifically studied the gas leakage caused by the formation of sand holes. The prior art, with respect to the problem of sand hole leakage, has mostly focused on studying how to repair electrical equipment with sand holes after detecting gas leakage. For example, Chinese patent CN217977350U discloses a plugging device and electrical equipment for sulfur hexafluoride leakage from sand holes in electrical equipment, which uses a sealed connection fixing sleeve and a plugging member to achieve sand hole plugging. It can be seen that there are currently few devices or methods specifically for accurate simulation or detection of gas leakage caused by the formation of sand holes, especially research on the detection of leaking O2 concentration. Therefore, how to accurately simulate and detect the hole leakage characteristics of C4F7N / CO2 / O2 mixed gas has become a problem that needs to be solved in this field. Summary of the invention

[0004] The purpose of the present invention is to provide a sand hole leakage defect simulation test device and an oxygen leakage concentration detection method in order to overcome the defects of the above-mentioned prior art that it is difficult to achieve accurate simulation of sand hole leakage defects and accurate detection of O2 leakage concentration in mixed gas.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] According to a first aspect of the present invention, a sand hole leakage defect simulation test device is provided, comprising a mixed gas supply module, a first pressure balance adjustment module, a second pressure balance adjustment module, a sand hole leakage defect simulation module, a ventilation module and a plurality of gas on-off control structures.

[0007] The sand hole leakage defect simulation module includes a closed cavity and a sand hole leakage defect shell located inside the closed cavity, a temperature and pressure measuring unit, a cooling unit, a heating unit and a capillary unit, wherein the temperature and pressure measuring unit is connected to the top outer wall of the sand hole leakage defect shell, the cooling unit is closely attached to the outer wall of the sand hole leakage defect shell, the heating unit is located inside the sand hole leakage defect shell, and the capillary unit extends from the bottom of the sand hole leakage defect shell into the shell to communicate with it;

[0008] The mixed gas providing module is connected to the first pressure balance regulating module, the first pressure balance regulating module is connected to the upper surface of the sand hole leakage defect shell, the second pressure balance regulating module is connected to the first pressure balance regulating module through a first gas on-off control structure, and the ventilation module is connected to the sand hole leakage defect simulation module through multiple gas on-off control structures.

[0009] As a preferred technical solution, the heating unit includes a heating rod, and the heating rod is connected to the top inner wall of the sand hole leakage defect shell.

[0010] As a preferred technical solution, the capillary unit includes a needle tube.

[0011] As a preferred technical solution, the cooling unit includes a semiconductor refrigeration structure, and the semiconductor refrigeration structure is wrapped around the outer wall of the shell with the sand hole leakage defect.

[0012] As a preferred technical solution, the first pressure balance regulating module includes a first branch and a second branch, the first branch includes a first compressor, a first buffer tank and a proportional valve connected in sequence, the other end of the first compressor is connected to the mixed gas supply module, and the other end of the proportional valve is connected to the upper surface of the shell with sand hole leakage defects, the second branch includes a second gas on-off control structure, a vacuum control subunit and a third gas on-off control structure connected in sequence, the other end of the second gas on-off control structure is connected to the mixed gas supply module, and the other end of the third gas on-off control structure is connected to the other end of the proportional valve.

[0013] As a preferred technical solution, the vacuum control subunit includes a vacuum gauge, a vacuum pump and a vacuum exhaust port, the vacuum gauge is connected to the vacuum pump, one end of the vacuum pump is connected between the second gas on-off control structure and the third gas on-off control structure, and the other end is connected to the vacuum exhaust port.

[0014] As a preferred technical solution, the second pressure balance regulation module includes a comprehensive detector, a needle valve, a second buffer tank and a second compressor connected in sequence, the other end of the second compressor is connected to the closed cavity, and the second buffer tank is connected between one end of the vacuum pump and the third gas on-off control structure through the first gas on-off control structure.

[0015] As a preferred technical solution, the mixed gas providing module includes a gas distributor, a fourth gas on-off control structure and a gas storage tank which are connected in sequence, and the gas storage tank is connected to the first pressure balance regulating module.

[0016] As a preferred technical solution, the ventilation module includes a ventilation port unit and a ventilation fan unit, the ventilation port unit includes a fifth gas on-off control structure and a ventilation port connected in sequence, the ventilation fan unit includes a sixth gas on-off control structure and a ventilation fan connected in sequence, the other end of the fifth gas on-off control structure and the other end of the sixth gas on-off control structure are respectively connected to the closed cavity.

[0017] According to a second aspect of the present invention, a method for detecting oxygen leakage concentration in a sand hole leakage defect simulation test is provided. The detection method is implemented using the device described above, and the detection method comprises the following steps:

[0018] A pressure difference obtaining step, heating the C4F7N / CO2 / O2 mixed gas to 500° C. twice to obtain the pressure difference of the C4F7N / CO2 / O2 mixed gas;

[0019] The pressure drop value obtaining step is as follows: after the first heating, the gas pressure in the closed cavity is increased, the current annual leakage rate of C4F7N and the annual leakage rate of CO2 are obtained, and the pressure drop value of C4F7N and the pressure drop value of CO2 are calculated respectively by using the pressure drop method;

[0020] The step of obtaining the annual leakage rate of O2 is to calculate the pressure drop value of O2 based on the pressure difference, the pressure drop value of C4F7N and the pressure drop value of CO2, and to reversely calculate the annual leakage rate of O2 using the pressure drop method, wherein the expression of the pressure drop value of O2 is:

[0021]

[0022] Where ΔP O2 Indicates the O2 pressure drop, ΔP 500 Indicates the pressure difference before and after leakage at 500℃, ΔP C4 Indicates the pressure drop of C4F7N, ΔP CO2 Indicates the CO2 pressure drop value.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention adopts a capillary unit to simulate a capillary straight tube-shaped sand hole, and sets a heating unit inside the sand hole leakage defect shell. During the detection process, the temperature of the mixed gas in the sand hole leakage defect shell can be increased to 500°C by the heating unit, and the temperature of the mixed gas can be lowered by the cooling unit, and then the temperature of the mixed gas can be heated to 500°C again, which can expand the pressure difference of the mixed gas twice to 2.64 times, reduce the influence of the detection error on the calculation result, so as to obtain a more accurate and effective pressure difference value, and calculate a more accurate O2 annual leakage rate according to the pressure drop method, improve the accuracy of the simulation of the sand hole leakage defect, enrich the research on the leakage characteristics of the C4F7N / CO2 / O2 mixed gas, and help to ensure the safe operation of power equipment;

[0025] 2. The present invention uses a needle tube as a capillary unit to simulate the sand hole leakage port. Different lengths can be selected according to the test objectives to simulate different sand hole airway lengths, and different diameters can be selected to simulate different sand hole aperture sizes, so that the sand hole leakage defect is closer to the actual situation. The structure is simple and accurate simulation can be achieved, further improving the accuracy of the test results.

[0026] 3. The present invention only adopts the setting of heating unit and capillary unit, which can realize accurate simulation and detection of sand hole leakage defects, is simple to operate, and is conducive to saving test costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the device in an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the structure of a mixed gas providing module in an embodiment of the present invention;

[0029] Figure 3 It is a structural schematic diagram of a sand hole leakage defect simulation module in an embodiment of the present invention;

[0030] Figure 4 This is a structural schematic diagram of a first pressure balance adjustment module in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the structure of the second pressure balance adjustment module in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the structure of a ventilation module in an embodiment of the present invention;

[0033] Wherein: 1. mixed gas supply module; 2. first pressure balance regulating module; 3. second pressure balance regulating module; 4. sand hole leakage defect simulation module; 5. ventilation module; 11. gas distributor; 12. gas storage tank; 21. first compressor; 22. first buffer tank; 23. proportional valve; 24. vacuum control subunit; 241. vacuum gauge; 242. vacuum pump; 243. vacuum exhaust port; 31. comprehensive detector; 32. needle valve; 33. second buffer tank; 34. second compressor; 41. closed cavity; 42. sand hole leakage defect shell; 43. temperature and pressure measuring unit; 431. temperature sensor; 432. pressure sensor; 44. semiconductor refrigeration structure; 45. heating rod; 46. needle tube; 51. ventilation port; 52. ventilation fan; 61. first solenoid valve; 62. second solenoid valve; 63. third solenoid valve; 64. fourth solenoid valve; 65. fifth solenoid valve; 66. sixth solenoid valve. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0035] Example 1

[0036] like Figure 1As shown, this embodiment provides a sand hole leakage defect simulation test device, which includes a mixed gas supply module 1, a first pressure balance adjustment module 2, a second pressure balance adjustment module 3, a sand hole leakage defect simulation module 4, a ventilation module 5 and multiple gas on-off control structures. The gas on-off control structure in this embodiment uses solenoid valves, which are the first solenoid valve 61, the second solenoid valve 62, the third solenoid valve 63, the fourth solenoid valve 64, the fifth solenoid valve 65 and the sixth solenoid valve 66.

[0037] like Figure 2 As shown, the mixed gas providing module 1 includes a gas distributor 11 , a fourth solenoid valve 64 and a gas storage tank 12 which are connected in sequence, and the gas storage tank 12 is connected to the first pressure balance regulating module 2 .

[0038] like Figure 3 As shown, the sand hole leakage defect simulation module 4 includes a closed cavity 41 and a sand hole leakage defect shell 42 located inside the closed cavity 41, a temperature and pressure measuring unit 43, a cooling unit, a heating unit and a capillary unit. In this embodiment, the temperature and pressure measuring unit 43 uses a temperature sensor 431 and a pressure sensor 432, which are respectively connected to the top outer wall of the sand hole leakage defect shell 42, the cooling unit uses a semiconductor refrigeration structure 44, the heating unit uses a heating rod 45, and the capillary unit uses a needle tube 46. Among them, the semiconductor refrigeration structure 44 is wrapped around the outer wall of the sand hole leakage defect shell 42, the heating rod 45 is located inside the sand hole leakage defect shell 42, and is connected to the top inner wall of the sand hole leakage defect shell 42; the needle tube 46 extends from the bottom of the sand hole leakage defect shell 42 into the shell and communicates with it.

[0039] Depend on Figures 1 to 3 It can be seen that the mixed gas providing module 1 is connected to the first pressure balance regulating module 2, the first pressure balance regulating module 2 is connected to the upper surface of the sand hole leakage defect shell 42, the second pressure balance regulating module 3 is connected to the first pressure balance regulating module 2 through the first solenoid valve 61, and the ventilation module 5 is connected to the sand hole leakage defect simulation module 4 through the fifth solenoid valve 65 and the sixth solenoid valve 66.

[0040] like Figure 4As shown, the first pressure balance regulating module 2 includes a first branch and a second branch. The first branch includes a first compressor 21, a first buffer tank 22 and a proportional valve 23 connected in sequence. The other end of the first compressor 21 is connected to the gas storage tank 12 in the mixed gas supply module 1, and the other end of the proportional valve 23 is connected to the upper surface of the sand hole leakage defect housing 42. The second branch includes a second solenoid valve 62, a vacuum control subunit 24 and a third solenoid valve 63 connected in sequence. The other end of the second solenoid valve 62 is connected to the gas storage tank 12 in the mixed gas supply module 1, and the other end of the third solenoid valve 63 is connected to the other end of the proportional valve 23. The vacuum control subunit 24 includes a vacuum gauge 241, a vacuum pump 242 and a vacuum exhaust port 243. The vacuum gauge 241 is connected to the vacuum pump 242. One end of the vacuum pump 242 is connected between the second solenoid valve 62 and the third solenoid valve 63, and the other end is connected to the vacuum exhaust port 243.

[0041] like Figure 5 As shown, the second pressure balance regulating module 3 includes a comprehensive detector 31, a needle valve 32, a second buffer tank 33 and a second compressor 34 connected in sequence, the other end of the second compressor 34 is connected to the closed cavity 41, and the second buffer tank 33 is connected between one end of the vacuum pump 242 and the third solenoid valve 63 through the first solenoid valve 61.

[0042] like Figure 6 As shown, the ventilation module 5 includes a ventilation port unit and a ventilation fan unit. The ventilation port unit includes a fifth solenoid valve 65 and a ventilation port 51 connected in sequence. The ventilation fan unit includes a sixth solenoid valve 66 and a ventilation fan 52 connected in sequence. The other end of the fifth solenoid valve 65 and the other end of the sixth solenoid valve 66 are respectively connected to the closed cavity 41.

[0043] Based on the above device, the needle tube 46 structure is used to simulate the sand hole leakage port, the heating rod 45 can be used to increase the temperature of the C4F7N / CO2 / O2 mixed gas in the sand hole leakage defect shell 42, and the semiconductor refrigeration structure 44 can be used to reduce the temperature of the mixed gas so that the heating rod 45 can heat the mixed gas again. Combined with the mixed gas providing module 1, the first pressure balance adjustment module 2, the second pressure balance adjustment module 3, the ventilation module 5 and the temperature and pressure measuring unit 43 in the sand hole leakage defect simulation module 4, the sand hole leakage defect can be accurately simulated, and the required data can be recorded according to the display of the temperature and pressure measuring unit 43, so that the concentration of O2 in the leaked mixed gas can be directly calculated.

[0044] Example 2

[0045] This embodiment provides a method for detecting oxygen leakage concentration in a sand hole leakage defect simulation test, and the detection method comprises the following steps:

[0046] A pressure difference obtaining step, heating the C4F7N / CO2 / O2 mixed gas to 500° C. twice to obtain the pressure difference of the C4F7N / CO2 / O2 mixed gas;

[0047] The pressure drop value obtaining step is as follows: after the first heating, the gas pressure in the closed cavity is increased, the current annual leakage rate of C4F7N and the annual leakage rate of CO2 are obtained, and the pressure drop value of C4F7N and the pressure drop value of CO2 are calculated respectively by using the pressure drop method;

[0048] The steps for obtaining the annual leakage rate of O2 are as follows: based on the pressure difference, the pressure drop value of C4F7N and the pressure drop value of CO2, the pressure drop value of O2 is calculated, and the annual leakage rate of O2 is calculated back by the pressure drop method.

[0049] The above method can be implemented using the simulation test device in Example 1, and the specific process is as follows:

[0050] (1) Open the first solenoid valve 61, the second solenoid valve 62 and the third solenoid valve 63, and open the proportional valve 23 to fully open the aperture, start the vacuum pump 242, and evacuate the gas storage tank 12, the first buffer tank 22 and the shell 42 with sand hole leakage defects until the pressure displayed on the vacuum gauge 241 is 133 Pa, eliminating the interference of residual gas;

[0051] (2) The above-mentioned solenoid valve is closed, the fourth solenoid valve 64 is opened, and the gas distributor 11 is started to prepare a C4F7N / CO2 / O2 mixed gas with a target mixing ratio of a%:b%:c% (generally, C4F7N accounts for 0-10%, CO2 accounts for 80-90%, and O2 accounts for 0-10%). The mixed gas enters the gas storage tank 12, and the first compressor 21 is started to pressurize the gas to (P r +1)MPa(P r The mixed gas enters the first buffer tank 22, the proportional valve 23 is opened until the aperture is fully opened, and the mixed gas enters the sand hole leakage defect housing 42. At this time, the temperature sensor 431 and the pressure sensor 432 detect the mixed gas temperature T and pressure P in the sand hole leakage defect housing 42;

[0052] (3) Calculate according to the ideal gas state equation:

[0053] PM=ρRT (1)

[0054] Wherein, P is the gas pressure, unit: Pa; M is the relative molar mass of the gas, unit: g / mol; ρ is the density; R is a constant; T is the gas temperature, unit K.

[0055] According to Dalton's law of partial pressure:

[0056] P mix =P C4*a%+P CO2 *b%+P O2 *c% (2)

[0057] Where P mix , P C4 , P CO2 , P O2 They are respectively the gas pressures of mixed gas, C4F7N, CO2 and O2, unit: MPa.

[0058] According to equations (1) and (2), the pressure and temperature of the mixed gas are proportional.

[0059] Continue with step (2). Since the required inflation pressure for the electrical equipment during operation is the rated pressure P at 20°C, r In order to accurately simulate the actual operating state of the electrical equipment, the mixed gas pressure P in the current sand hole leakage defect shell 42 is automatically calculated and converted to P at 20°C. t :

[0060]

[0061] If P t ≥P r -0.05, at this time, the gas pressure of the shell 42 with sand hole leakage defect is close to the target pressure, in order to reduce the actual pressure after inflation and P r Deviation, at this time, the aperture of the proportional valve 23 is reduced to half of the fully open state, the gas flow rate is reduced, and the gas is slowly filled into the shell 42 with sand hole leakage defects to ensure the accuracy of the inflation pressure; on the contrary, the aperture of the proportional valve 23 is fully opened for inflation; after the inflation is completed, the proportional valve 23 and the third solenoid valve 63 are closed, and the aforementioned gas distribution instrument 11 and the first compressor 21 are stopped, and the leakage simulation test phase is entered at this time;

[0062] (5) Based on the characteristics of the sand hole leakage being similar to a capillary straight pipe, a needle tube 46 is used to simulate the leakage port. The needle tube 46 can be selected in different lengths according to the test objectives to simulate different sand hole airway lengths, and different diameters can be selected to simulate different sand hole aperture sizes; and the gas temperature can be controlled (forward conduction for cooling, reverse conduction for heating) by a semiconductor refrigeration structure 44 wrapped around the outer wall of the sand hole leakage defect shell 42 to simulate different ambient temperatures; the mixed gas leaks into the closed cavity 41 along the needle tube 46 (simulating the test conditions of the local bandaging method and the buckle cover method, the internal space is large, and the leaked trace gas will not cause pressure changes);

[0063] At this time, the heating rod 45 is started to heat the gas to 500°C. According to formula (1), the gas pressure rises by about 2.64 times (taking the experimental temperature as 20°C as an example). The value P of the pressure sensor 432 at this time is recorded. 500,0Then start the semiconductor refrigeration structure 44 to cool the gas and quickly drop the gas temperature to the test temperature T c At this time, the fifth solenoid valve 65 and the sixth solenoid valve 66 are opened, and the ventilation port 51 and the ventilation fan 52 are started for 1 minute to replace the air in the closed cavity 41 and eliminate the interference of leaking gas during heating; then the formal test is carried out;

[0064] (6) After 24 hours of the formal test, the second compressor 34 was started to pressurize the gas in the closed chamber 41 to 0.2 MPa and enter the second buffer tank 33. The integrated detector 31 was turned on and the needle valve 32 was adjusted to a flow rate of 300 ml / min. After 3 minutes, the C4F7N and CO2 concentration increments ΔC were recorded. C4 and ΔC CO2 ; Turn off the above-mentioned integrated detector 31, the second compressor 34; calculate the absolute leakage rate F of C4F7N and CO2 according to the following formula n :

[0065]

[0066] In the formula, F n Unit: Pa·m 3 / s, n can be C4F7N and CO2; ΔC n V is the increment of the measured gas concentration in the closed cavity 41 during the measurement period, in ppm, where n can be C4F7N or CO2; m It is the residual value of the effective volume of the closed cavity 41 minus the volume of the shell 42 due to the sand hole leakage defect, unit: m 3 ;P atm is the atmospheric pressure during the measurement, unit: Pa; Δt is the measured ΔC n The interval time is in seconds (s);

[0067] Further calculation of the annual leakage rate F of C4F7N and CO2 y,n :

[0068]

[0069] In the formula, F y,n Unit: % / year, n can be C4F7N and CO2; V is the effective volume of the shell 42 with sand hole leakage defect, unit: m 3 ; C n is the gas volume ratio, n can be C4F7N and CO2;

[0070] (7) Start the heating rod 45 again to heat the gas to 500°C. As above, record the value P of the pressure sensor 432 at this time. 500,1; Since the amount of leaked gas is small, the pressure change is not obvious at normal test temperature. In this embodiment, the pressure difference before and after the leakage is increased by about 2.64 times by heating, so as to reduce the pressure measurement error (the error of the pressure sensor 432 is a constant value. The larger the pressure difference, the smaller the impact of the error and the higher the accuracy). At this time, the pressure difference ΔP before and after the leakage at 500°C 500 =P 500,1 -P 500,0 ;

[0071] Calculate the pressure drop ΔP caused by C4F7N and CO2 leakage according to the pressure drop method n :

[0072]

[0073] Where ΔP n To convert to pressure at 20℃, the unit is MPa, and n can be C4F7N and CO2;

[0074] According to formula (6), ΔP C4 and ΔP CO2 , calculate the pressure drop ΔP caused by O2 leakage O2 :

[0075]

[0076] According to formula (6), the annual O2 leakage rate F is calculated y,O2 , and then calculate the total annual leakage rate F according to the mixing ratio (the leakage amount is small, and the mixing ratio is assumed to be unchanged before and after the leakage) y :

[0077] F y =F y,C4 *a%+F y,CO2 *b%+F y,O2 *c%

[0078] (8) If you want to conduct tests at other temperature points, repeat steps (5) to (7); if you want to conduct tests at other mixing ratios or sand hole defect models (different needle tube lengths and diameters), repeat steps (1) to (7).

[0079] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A sand hole leakage defect simulation test device, characterized in that: It includes a mixed gas supply module, a first pressure balance adjustment module, a second pressure balance adjustment module, a sand hole leakage defect simulation module, a ventilation module and multiple gas on-off control structures. The sand hole leakage defect simulation module includes a closed cavity and a sand hole leakage defect shell located inside the closed cavity, a temperature and pressure measuring unit, a cooling unit, a heating unit and a capillary unit, wherein the temperature and pressure measuring unit is connected to the top outer wall of the sand hole leakage defect shell, the cooling unit is closely attached to the outer wall of the sand hole leakage defect shell, the heating unit is located inside the sand hole leakage defect shell, and the capillary unit extends from the bottom of the sand hole leakage defect shell into the shell to communicate with it; The mixed gas providing module is connected to the first pressure balance regulating module, the first pressure balance regulating module is connected to the upper surface of the sand hole leakage defect shell, the second pressure balance regulating module is connected to the first pressure balance regulating module through a first gas on-off control structure, and the ventilation module is connected to the sand hole leakage defect simulation module through multiple gas on-off control structures.

2. The sand hole leakage defect simulation test device according to claim 1 is characterized in that: The heating unit comprises a heating rod, and the heating rod is connected to the top inner wall of the sand hole leakage defect shell.

3. The sand hole leakage defect simulation test device according to claim 1 is characterized in that: The capillary unit includes a needle tube.

4. The sand hole leakage defect simulation test device according to claim 1 is characterized in that: The cooling unit comprises a semiconductor refrigeration structure, and the semiconductor refrigeration structure is wrapped around the outer wall of the shell with sand hole leakage defect.

5. The sand hole leakage defect simulation test device according to claim 1 is characterized in that: The first pressure balance regulating module includes a first branch and a second branch. The first branch includes a first compressor, a first buffer tank and a proportional valve connected in sequence. The other end of the first compressor is connected to the mixed gas supply module, and the other end of the proportional valve is connected to the upper surface of the shell with sand hole leakage defects. The second branch includes a second gas on-off control structure, a vacuum control subunit and a third gas on-off control structure connected in sequence. The other end of the second gas on-off control structure is connected to the mixed gas supply module, and the other end of the third gas on-off control structure is connected to the other end of the proportional valve.

6. The sand hole leakage defect simulation test device according to claim 5 is characterized in that: The vacuum control subunit includes a vacuum gauge, a vacuum pump and a vacuum exhaust port. The vacuum gauge is connected to the vacuum pump. One end of the vacuum pump is connected between the second gas on-off control structure and the third gas on-off control structure, and the other end is connected to the vacuum exhaust port.

7. The sand hole leakage defect simulation test device according to claim 6 is characterized in that: The second pressure balance regulating module includes a comprehensive detector, a needle valve, a second buffer tank and a second compressor connected in sequence, the other end of the second compressor is connected to the closed cavity, and the second buffer tank is connected between one end of the vacuum pump and the third gas on-off control structure through the first gas on-off control structure.

8. The sand hole leakage defect simulation test device according to claim 1 is characterized in that: The mixed gas providing module comprises a gas distributor, a fourth gas on-off control structure and a gas storage tank which are connected in sequence, and the gas storage tank is connected to the first pressure balance regulating module.

9. The sand hole leakage defect simulation test device according to claim 1, characterized in that: The ventilation module includes a ventilation port unit and a ventilation fan unit, the ventilation port unit includes a fifth gas on-off control structure and a ventilation port connected in sequence, the ventilation fan unit includes a sixth gas on-off control structure and a ventilation fan connected in sequence, the other end of the fifth gas on-off control structure and the other end of the sixth gas on-off control structure are respectively connected to the closed cavity.

10. A method for detecting oxygen leakage concentration in a sand hole leakage defect simulation test, characterized in that: The detection method is implemented using the device according to any one of claims 1 to 9, and the detection method comprises the following steps: A pressure difference obtaining step, heating the C4F7N / CO2 / O2 mixed gas to 500° C. twice to obtain the pressure difference of the C4F7N / CO2 / O2 mixed gas; The pressure drop value obtaining step is as follows: after the first heating, the gas pressure in the closed cavity is increased, the current annual leakage rate of C4F7N and the annual leakage rate of CO2 are obtained, and the pressure drop value of C4F7N and the pressure drop value of CO2 are calculated respectively by using the pressure drop method; The step of obtaining the annual leakage rate of O2 is to calculate the pressure drop value of O2 based on the pressure difference, the pressure drop value of C4F7N and the pressure drop value of CO2, and to reversely calculate the annual leakage rate of O2 using the pressure drop method, wherein the expression of the pressure drop value of O2 is: In the formula, ΔP O2 Indicates the O2 pressure drop value, ΔP 500 Indicates the pressure difference before and after leakage at 500℃, ΔP C4 Indicates the pressure drop of C4F7N, ΔP CO2 Indicates the CO2 pressure drop value.

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