Sealing Ring Leakage Defect Simulation Device, Oxygen Concentration Detection Device and Method

Abstract

The present invention relates to a simulation device for seal leakage defects, an oxygen concentration detection device and a method. The oxygen concentration detection device includes a mixed gas supply module, a pressure balance adjustment module, a seal leakage defect simulation module, and a ventilation module. Each module is provided with a plurality of gas on-off control structures. The seal leakage defect simulation module includes a pressure balance adjustment unit, a sealed cavity, and a seal leakage defect housing located inside it, a temperature and pressure measurement unit, a cooling unit, a heating unit, and a seal simulation 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, the seal simulation unit is communicated with the bottom of the housing, and the pressure balance adjustment unit is connected to the sealed cavity. Compared with the prior art, the present invention has the advantages of effectively improving the accuracy of seal leakage defect simulation and the accuracy of oxygen leakage concentration detection, etc.

Description

Technical Field

[0001] The present invention relates to the field of gas leakage, and in particular to a simulation device for seal leakage defects, an oxygen concentration detection device and a method therefor. Background Art

[0002] Generally, seals are placed at the joints of the gas chambers of electrical equipment. After long-term operation, the seals age, resulting in flat fissures at the pipe joints. 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. The State Grid requires that the annual leakage rate of electrical equipment should not exceed 0.5%. Therefore, leak detection of electrical equipment is an essential part of daily operation and maintenance. Referring to the standard GB / T 11023-2018, on-site leak detection mainly uses the local bandaging method or the hood method, and the gas concentration leaking into the closed structure is detected after a certain time (24 h), and the leakage rate of the electrical equipment is obtained by calculation.

[0003] Since the air contains a high concentration of O 2 , the leaked O 2 at the ppm level (volume ratio of one in a million) is difficult to detect by a detection instrument. Therefore, in the prior art, the leakage rate of the C 4 F 7 N or CO 2 concentration in the closed structure is mainly detected, and then the leakage rate of the C 4 F 7 N / CO 2 / O 2 mixed gas is directly calculated according to the mixing ratio. The calculation result has a large deviation from the actual value, which may lead to misjudgment of the leakage state of the electrical equipment, and then trigger a relatively serious power operation accident. In addition, in the prior art, there is no research specifically on seal leakage defects, nor on the precise simulation of seal leakage defects and the detection of O 2 leakage concentration, which severely restricts the research on the leakage characteristics of the C 4 F 7 N / CO 2 / O 2 mixed gas caused by seal defects. Therefore, how to accurately simulate and detect the seal leakage defect characteristics of the C 4 F 7 N / CO 2 / O 2 mixed gas has become a problem to be solved in this field. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art, which are difficult to accurately simulate seal leakage defects and O 2To address the defect of accurate detection of leakage concentration, a simulation device for seal leakage defects, an oxygen concentration detection system, and a method are provided.

[0005] The object of the present invention can be achieved through the following technical solutions:

[0006] According to the first aspect of the present invention, a simulation device for seal leakage defects is provided. The device is used to detect the oxygen leakage concentration in the C 4 F 7 N / CO 2 / O 2 mixed gas. The device includes a pressure balance adjustment unit, a sealed cavity, and a seal leakage defect housing, a temperature and pressure measurement unit, a cooling unit, a heating unit, and a seal simulation unit located inside the sealed cavity. The temperature and pressure measurement unit is connected to the outer wall of the top of the seal leakage defect housing. The cooling unit is closely attached to the outer wall of the seal leakage defect housing. The heating unit is located inside the seal leakage defect housing. The seal simulation unit is connected to the bottom of the seal leakage defect housing. The pressure balance adjustment unit is connected to the sealed cavity.

[0007] Among them, the heating unit is used to heat the C 4 F 7 N / CO 2 / O 2 mixed gas. The cooling unit is used to reduce the temperature of the C 4 F 7 N / CO 2 / O 2 mixed gas. The pressure balance adjustment unit is used to adjust the gas pressure in the sealed cavity.

[0008] As a preferred technical solution, the seal simulation unit includes a fine iron wire and a seal. The fine iron wire is embedded in the seal, and the seal is connected to the bottom of the seal leakage defect housing.

[0009] As a preferred technical solution, the heating unit includes a heating rod, and the heating rod is connected to the seal simulation unit.

[0010] According to the second aspect of the present invention, there is provided an oxygen concentration detection device for seal ring leakage defects, including a mixed gas supply module, a pressure balance adjustment module, a seal ring leakage defect simulation module, a gas exchange module, and a plurality of gas on-off control structures. The seal ring leakage defect simulation module includes the seal ring leakage defect simulation device. The mixed gas supply module is connected to the pressure balance adjustment module. The pressure balance adjustment module is communicated with the upper surface of the seal ring leakage defect housing. The pressure balance adjustment unit is connected to the pressure balance adjustment module through a first gas on-off control structure. The gas exchange module is connected to the seal ring leakage defect simulation module through a plurality of gas on-off control structures.

[0011] According to the third aspect of the present invention, there is provided a method for detecting the oxygen concentration of seal ring leakage defects, including the following steps:

[0012] S1, heat the C 4 F 7 N / CO 2 / O 2 mixed gas to 500 °C, record the first pressure, and place the C 4 F 7 N / CO 2 / O 2 mixed gas in the seal ring leakage defect housing, and place the seal ring leakage defect housing in a sealed cavity;

[0013] S2, lower the current C 4 F 7 N / CO 2 / O 2 mixed gas temperature to displace the gas in the sealed cavity;

[0014] S3, increase the gas pressure in the sealed cavity, record the current C 4 F 7 N and CO 2 concentration increments, and calculate the annual leakage rate of C 4 F 7 N and the annual leakage rate of CO 2 respectively;

[0015] S4, heat the current C 4 F 7 N / CO 2 / O 2 mixed gas to 500 °C again, record the second pressure, and calculate the pressure difference between the first pressure and the second pressure;

[0016] S5, based on the pressure difference, calculate the total annual leakage rate using the pressure drop method;

[0017] S6. Calculate the annual leakage rate of O based on the mixing ratio, the total annual leakage rate, the annual leakage rate of C F N, and the annual leakage rate of CO, where the mixing ratio is preset. 4 F 7 and the annual leakage rate of CO 2 to calculate the annual leakage rate of O 2 , where the mixing ratio is preset.

[0018] As a preferred technical solution, the calculation formula for the annual leakage rate of O 2 is:

[0019]

[0020] In the formula, F y,O2 represents the annual leakage rate of O 2 , F y represents the total annual leakage rate, F y,C4 represents the annual leakage rate of C 4 F 7 N, F y,Co2 represents the annual leakage rate of CO 2 , a%, b%, and c% are the proportions of C 4 F 7 N, CO 2 , and O 2 in the C 4 F 7 N / CO 2 / O 2 mixed gas.

[0021] As a preferred technical solution, the calculation formula for the total annual leakage rate is:

[0022]

[0023] In the formula, F y represents the total annual leakage rate, ΔP 500 represents the pressure difference before and after leakage at 500 °C, P r represents the rated pressure at 20 °C, and Δt represents the measurement interval time.

[0024] As a preferred technical solution, the process of recording the current concentration increments of C F N and CO and calculating the annual leakage rates of C F N and CO respectively includes calculating the absolute leakage rates of C F N and CO based on the concentration increments of C F N and CO. 4 F 7 N and CO 2 concentration increments, and calculating the annual leakage rates of C 4 F 7 N and CO 2 includes, based on the concentration increments of C 4 F 7 N and CO 2 concentration increments, calculating the absolute leakage rates of C 4 F 7 N and CO 2Absolute leakage rate; according to the described C 4 F 7 N absolute leakage rate and the described CO 2 Absolute leakage rate, respectively calculate the described C 4 F 7 N annual leakage rate and the described CO 2 Annual leakage rate.

[0025] As a preferred technical solution, the described C 4 F 7 N absolute leakage rate and the described CO 2 The calculation formula for the absolute leakage rate is:

[0026]

[0027] In the formula, F n Represents the absolute leakage rate, ΔC n Represents the increment of the concentration of the measured gas in the sealed cavity during the measurement time period Δt. n can both take C 4 F 7 N and CO 2 ; V m Represents the remaining value of the effective volume of the sealed cavity minus the volume of the housing with seal leakage defects; P atm Represents the atmospheric pressure during the measurement period.

[0028] As a preferred technical solution, the described C 4 F 7 N annual leakage rate and the described CO 2 The calculation formula for the annual leakage rate is:

[0029]

[0030] In the formula, F y,n Represents the annual leakage rate, C n Is the gas volume ratio. n can both take C 4 F 7 N and CO 2 ; V is the effective volume of the housing with seal leakage defects.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention sets the heating unit inside the housing with seal leakage defects for heating C 4 F 7 N / CO 2 / O 2For the mixed gas, by using a cooling unit to lower the temperature of the mixed gas and then heating the temperature of the mixed gas to 500 °C again, the pressure difference between the mixed gases before and after can be expanded to 2.64 times, reducing the impact of detection errors on the calculation results, so as to obtain a more accurate and effective pressure difference value. Furthermore, the total annual leakage rate is obtained according to the pressure drop method. At the same time, a pressure balance adjustment unit is used to adjust the gas pressure in the sealed cavity to obtain C 4 F 7 N and CO 2 concentration increment so as to calculate C 4 F 7 N and CO 2 annual leakage rate, and the O annual leakage rate is obtained in combination with the total annual leakage rate, which can effectively improve the accuracy of the simulation of the seal leakage defect and ensure the safe operation of the power equipment; 2 The annual leakage rate can effectively improve the accuracy of the simulation of the seal leakage defect and ensure the safe operation of the power equipment;

[0033] 2. The present invention uses a thin iron wire and a sealing ring as a sealing ring simulation unit. The thin iron wire is embedded in the sealing ring to simulate the flat crack that appears at the pipe connection due to the aging of the sealing ring in reality, making the seal leakage defect closer to the actual working state of the power equipment. Moreover, different lengths of thin iron wires can be selected according to the test objectives to simulate different seal leakage airway widths, and sealing rings with different inner diameters can be selected to simulate different seal leakage airway depths, effectively enriching the test data, further improving the accuracy of the oxygen concentration detection of the seal leakage defect, and having a simple structure, convenient operation, and cost savings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of the overall structure of the device in the embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of the structure of the mixed gas supply module in the embodiment of the present invention;

[0036] Figure 3 is a schematic diagram of the structure of the seal leakage defect simulation module in the embodiment of the present invention;

[0037] Figure 4 is a schematic diagram of the structure of the pressure balance adjustment unit in the embodiment of the present invention;

[0038] Figure 5 is a schematic diagram of the structure of the pressure balance adjustment module in the embodiment of the present invention;

[0039] Figure 6 is a schematic diagram of the structure of the air exchange module in the embodiment of the present invention;

[0040] Wherein: 1. Mixed gas supply module; 2. Pressure balance adjustment module; 3. Seal leakage defect simulation module; 4. Ventilation module; 11. Gas distributor; 12. Gas storage tank; 21. First compressor; 22. First buffer tank; 23. Proportion valve; 24. Vacuum control sub-unit; 241. Vacuum gauge; 242. Vacuum pump; 243. Vacuum exhaust port; 31. Pressure balance adjustment unit; 311. Comprehensive detector; 312. Needle valve; 313. Second buffer tank; 314. Second compressor; 32. Sealed cavity; 33. Seal leakage defect housing; 34. Temperature and pressure measurement unit; 341. Temperature sensor; 342. Pressure sensor; 35. Semiconductor refrigeration structure; 36. Heating rod; 37. Seal simulation unit; 371. Fine iron wire; 372. Seal; 41. Ventilation port; 42. Exhaust fan; 51. First solenoid valve; 52. Second solenoid valve; 53. Third solenoid valve; 54. Fourth solenoid valve; 55. Fifth solenoid valve; 56. Sixth solenoid valve. Specific embodiments

[0041] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation manners and specific operation processes, 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 terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply 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 this structure must be completely horizontal, but can be slightly inclined.

[0042] 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 quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality" means two or more, unless otherwise specifically defined.

[0043] Embodiment 1

[0044] As Figure 1As shown in the figure, this embodiment provides an oxygen concentration detection device for seal ring leakage defects, including a mixed gas supply module 1, a pressure balance adjustment module 2, a seal ring leakage defect simulation module 3, a ventilation module 4, and a plurality of gas on-off control structures. The gas on-off control structures in this embodiment use electromagnetic valves, including a first electromagnetic valve 51, a second electromagnetic valve 52, a third electromagnetic valve 53, a fourth electromagnetic valve 54, a fifth electromagnetic valve 55, and a sixth electromagnetic valve 56.

[0045] As Figure 2 shown, the mixed gas supply module 1 includes a gas distributor 11, a fourth electromagnetic valve 54, and a gas storage tank 12 connected in sequence, and the gas storage tank 12 is connected to the pressure balance adjustment module 2.

[0046] The seal ring leakage defect simulation module 3 selects a seal ring leakage defect simulation device as Figure 3 shown, for detecting the oxygen leakage concentration in the C 4 F 7 N / CO 2 / O 2 mixed gas. This device includes a pressure balance adjustment unit 31, a sealed cavity 32, and a seal ring leakage defect housing 33, a temperature and pressure measurement unit 34, a cooling unit, a heating unit, and a seal ring simulation unit 37 located inside the sealed cavity 32. In this embodiment, the temperature and pressure measurement unit 34 selects a temperature sensor 341 and a pressure sensor 342, which are respectively connected to the outer wall of the top of the seal ring leakage defect housing 33; the cooling unit selects a semiconductor refrigeration structure 35, and the semiconductor refrigeration structure 35 is wrapped around the outer wall of the seal ring leakage defect housing 33; the heating unit selects a heating rod 36; the seal ring simulation unit 37 includes a thin iron wire 371 and a seal ring 372, the thin iron wire 371 is embedded in the seal ring 372, and the seal ring 372 is connected to the bottom of the seal ring leakage defect housing 33; the heating rod 36 is located inside the seal ring leakage defect housing 33 and is connected to the seal ring 372.

[0047] The pressure balance adjustment unit 31 is connected to the sealed cavity 32. As Figure 4 shown, the pressure balance adjustment unit 31 includes a comprehensive detector 311, a needle valve 312, a second buffer tank 313, and a second compressor 314 connected in sequence, and the other end of the second compressor 314 is connected to the sealed cavity 32.

[0048] It can be Figures 1 to 4 seen that the mixed gas supply module 1 is connected to the pressure balance adjustment module 2, the pressure balance adjustment module 2 is communicated with the upper surface of the seal ring leakage defect housing 33, the pressure balance adjustment unit 31 is connected to the pressure balance adjustment module 2 through the first electromagnetic valve 51, and the ventilation module 4 is connected to the seal ring leakage defect simulation module 3 through the fifth electromagnetic valve 55 and the sixth electromagnetic valve 56.

[0049] AsFigure 5 As shown, the pressure balance adjustment 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 communicates with the gas storage tank 12 in the mixed gas supply module 1. The other end of the proportional valve 23 communicates with the upper surface of the seal leakage defect housing 33. The second branch includes a second solenoid valve 52, a vacuum control sub-unit 24, and a third solenoid valve 53 connected in sequence. The other end of the second solenoid valve 52 is connected to the gas storage tank 12 in the mixed gas supply module 1. The other end of the third solenoid valve 53 is connected to the other end of the proportional valve 23. The vacuum control sub-unit 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 52 and the third solenoid valve 53, and the other end is connected to the vacuum exhaust port 243. Combining Figure 1 、 Figure 4 and Figure 5 it can be known that the second buffer tank 313 is connected between one end of the vacuum pump 242 and the third solenoid valve 53 through the first solenoid valve 51.

[0050] As Figure 6 shown, the ventilation module 4 includes a ventilation port unit and a ventilation fan unit. The ventilation port unit includes a fifth solenoid valve 55 and a ventilation port 41 connected in sequence. The ventilation fan unit includes a sixth solenoid valve 56 and a ventilation fan 42 connected in sequence. The other ends of the fifth solenoid valve 55 and the sixth solenoid valve 56 are respectively connected to the sealed cavity 32.

[0051] During the process of detecting the oxygen leakage concentration in the C 4 F 7 N / CO 2 / O 2 mixed gas, the heating rod 36 is used to heat the C 4 F 7 N / CO 2 / O 2 mixed gas, the semiconductor refrigeration structure 35 is used to reduce the temperature of the C 4 F 7 N / CO 2 / O 2 mixed gas so that the heating rod 36 can heat the mixed gas again. The pressure balance adjustment unit 31 is used to adjust the gas pressure in the sealed cavity 32. Combining the temperature and pressure measurement unit 34 in the mixed gas supply module 1, the pressure balance adjustment module 2, the ventilation module 4, and the seal leakage defect simulation module 3, it can accurately simulate the seal leakage defect and record the required data according to the display of the temperature and pressure measurement unit 34, and then can directly calculate the concentration of O 2 in the leaked mixed gas.

[0052] Example 2

[0053] This example provides a method for detecting the oxygen concentration of the leakage defect of a sealing ring. The detection method includes the following steps:

[0054] Step S1, heat the C 4 F 7 N / CO 2 / O 2 mixed gas to 500 °C, record the first pressure, and place the C 4 F 7 N / CO 2 / O 2 mixed gas in the sealing ring leakage defect housing 33, and place the sealing ring leakage defect housing 33 in the sealed cavity 32;

[0055] Step S2, reduce the current temperature of the C 4 F 7 N / CO 2 / O 2 mixed gas to displace the gas in the sealed cavity 32;

[0056] Step S3, increase the gas pressure in the sealed cavity 32, record the current concentration increments of C 4 F 7 N and CO 2 and calculate the annual leakage rates of C 4 F 7 N and CO 2 respectively;

[0057] Step S4, heat the current C 4 F 7 N / CO 2 / O 2 mixed gas to 500 °C again, record the second pressure, and calculate the pressure difference between the first pressure and the second pressure;

[0058] Step S5, calculate the total annual leakage rate by using the pressure drop method based on the pressure difference;

[0059] Step S6, calculate the annual leakage rate of O 4 F 7 N and CO 2 based on the mixing ratio, the total annual leakage rate, the annual leakage rates of C 2 where the mixing ratio is preset.

[0060] Implement the above method by using the detection device provided in Example 1. The implementation process is as follows:

[0061] (1) Open the first solenoid valve 51, the second solenoid valve 52, and the third solenoid valve 53, and open the proportional valve 23 to fully open the aperture. Start the vacuum pump 242 to evacuate the gas storage tank 12, the first buffer tank 22, and the shell 33 with a seal leakage defect to a pressure of 133 Pa shown on the vacuum gauge 241 to eliminate the interference of residual gas.

[0062] (2) Close the above solenoid valves, open the fourth solenoid valve 54, and start the gas distributor 11 to prepare a C 4 F 7 N / CO 2 / O 2 mixed gas with a target mixing ratio of a%:b%:c% (generally, the proportion of C 4 F 7 N is 0 - 10%, the proportion of CO 2 is 80 - 90%, and the proportion of O 2 is 0 - 10%). The mixed gas enters the gas storage tank 12, and start the first compressor 21 to boost the gas pressure to (P r +1) MPa (P r is the rated pressure of the test mixed gas) and enter the first buffer tank 22. Open the proportional valve 23 to fully open the aperture, and the mixed gas enters the shell 33 with a seal leakage defect. At this time, the temperature sensor 341 and the pressure sensor 342 detect the temperature T and pressure P of the mixed gas in the shell 33 with a seal leakage defect.

[0063] (3) Calculate according to the ideal gas state equation:

[0064] PM = ρRT (1)

[0065] In the formula, 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.

[0066] Then, according to Dalton's law of partial pressures:

[0067] P mix = P C4 *a% + P CO2 *b% + P O2 *c% (2)

[0068] In the formula, P mix , P C4 , P CO2 , P O2 are the gas pressures of the mixed gas, C 4 F 7 N, CO 2 , O 2 gas respectively, unit: MPa.

[0069] According to Equations (1) and (2), it can be seen that the pressure of the mixed gas is directly proportional to the temperature.

[0070] Continuing from step (2), since the inflation pressure required during the operation of the electrical equipment is the rated pressure P at 20°C r , to accurately simulate the actual operating state of the electrical equipment, the pressure P of the mixed gas in the current seal leakage defect housing 33 is automatically calculated and reduced to P at 20°C t :

[0071]

[0072] If P t ≥P r - 0.03, at this time the gas pressure in the seal leakage defect housing 33 is close to the target pressure. To reduce the deviation between the actual pressure after inflation and P r , at this time the aperture of the proportional valve 23 is reduced to 1 / 4 of the fully open state, the gas flow rate is reduced, and the seal leakage defect housing 33 is slowly filled to ensure the inflation pressure accuracy; otherwise, the proportional valve 23 is fully open for inflation; after inflation is completed, the proportional valve 23 and the third solenoid valve 53 are closed, and the previously used gas distribution instrument 11 and the first compressor 21 both stop running. At this time, it enters the leakage simulation test link;

[0073] (5) The main reason for seal leakage is that after the electrical equipment has been running for a long time, the seal ages, resulting in a flat - mouthed crack at the pipe connection. When the seal material is certain (i.e., the frictional resistance is certain), C 4 F 7 N / CO 2 / O 2 The leakage rate of the mixed gas is mainly determined by the length and depth of the crack and the pressure difference inside and outside the tank; for the above characteristics, the method of embedding a thin iron wire 371 is used to simulate seal leakage. Different lengths of thin iron wires 371 can be selected according to the test target to simulate different seal leakage airway widths, and different inner - diameter seals 372 can be selected to simulate different seal leakage airway depths; and the temperature of the gas can be controlled by the semiconductor refrigeration structure 35 wrapped around the outer wall of the seal leakage defect housing 33 (positive conduction for cooling, reverse conduction for heating) to simulate different ambient temperatures; the mixed gas leaks along the crack around the thin iron wire 371 into the closed cavity 32 (simulating the test conditions of the local bandaging method and the cover - buckling method, where the internal space is large and the tiny leaked gas will not cause pressure changes);

[0074] At this time, the heating rod 36 is started to heat the gas to 500°C. According to Equation (1), it can be known that the gas pressure rises by about 2.64 times (taking the experimental temperature of 20°C as an example), and the value P of the pressure sensor 342 at this time is recorded 500,0 ; then the semiconductor refrigeration structure 35 is started for refrigeration to quickly reduce the gas temperature to the test temperature T c, at this time, open the fifth solenoid valve 55 and the sixth solenoid valve 56. During the temperature reduction period, start the ventilation opening 41 and the ventilation fan 42 to replace the air in the sealed cavity 32 and eliminate the interference of the leaked gas during the heating period; then carry out the formal test;

[0075] (6) After 24 hours of the formal test, start the second compressor 314 to increase the pressure of the gas in the sealed cavity 32 to 0.2 MPa and enter the second buffer tank 313. Open the comprehensive detector 311, adjust the flow rate of the needle valve 312 to 300 ml / min, and record C at this time after 3 minutes 4 F 7 N and CO 2 concentration increment ΔC C4 and ΔC CO2 ; Close the above-mentioned comprehensive detector 311 and the second compressor 314; Calculate C according to the following formula 4 F 7 N and CO 2 absolute leakage rate F n :

[0076]

[0077] In the formula, F n Unit: Pa·m 3 / s, n can take C 4 F 7 N and CO 2 ; ΔC n is the increment of the concentration of the gas to be measured in the sealed tank during the measurement period, unit: ppm, n can take C 4 F 7 N and CO 2 ; V m is the remaining value of the effective volume of the sealed cavity 32 minus the volume of the seal leakage defect housing 33, unit: m 3 ; P atm is the atmospheric pressure during the measurement period, unit: Pa; Δt is the interval time for measuring ΔC n , unit is second (s);

[0078] Further calculate C 4 F 7 N and CO 2 annual leakage rate F y,n :

[0079]

[0080] In the formula, F y,n Unit: % / year, n can take C 4 F 7 N and CO 2 ; V is the effective volume of the seal leakage defect housing 33, unit: m3 ; C n is the gas volume ratio, and n can take C 4 F 7 N and CO 2 ;

[0081] (7) Restart the heating rod 36 again, heat the gas to 500 °C, and record the value P of the pressure sensor 342 at this time as above 500,1 ; Since the amount of leaked gas is small and the pressure change is not obvious at normal test temperatures, in this embodiment, the method of increasing the temperature is used to increase the pressure difference before and after leakage by about 2.64 times, so as to reduce the pressure measurement error (the error of the pressure sensor 342 is a fixed value, and the greater the pressure difference, the smaller the influence caused by the error and the higher the accuracy); at this time, the pressure difference ΔP before and after leakage at 500 °C 500 = P 500,1 - P 500,0 ;

[0082] Calculate the total annual leakage rate F according to the pressure drop method y :

[0083]

[0084] Calculate O according to the mixing ratio (the amount of leakage is small, and the mixing ratio before and after leakage is considered unchanged) 2 Annual leakage rate F y,O2 :

[0085]

[0086] In the formula, F y,C4 represents C 4 F 7 Annual leakage rate of N, F y,CO2 represents CO 2 Annual leakage rate.

[0087] (8) If tests at other temperature points are to be carried out, repeat steps (5) to (7); if other mixing ratios or seal ring defect models (different lengths of fine iron wires, inner diameters of seal rings) are to be carried out, repeat steps (1) to (7).

[0088] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning or limited experiments should be within the protection scope determined by the claims.

Claims

1. A simulation device for seal ring leakage defects, characterized in that, The device is used to detect C 4 F 7 N / CO 2 / O 2 the oxygen leakage concentration in the mixed gas. The device includes a pressure balance adjustment unit, a sealed cavity, and a seal leakage defect housing, a temperature and pressure measurement unit, a cooling unit, a heating unit, and a seal simulation unit located inside the sealed cavity. The temperature and pressure measurement unit is connected to the outer wall of the top of the seal leakage defect housing. The cooling unit is closely attached to the outer wall of the seal leakage defect housing. The heating unit is located inside the seal leakage defect housing. The seal simulation unit is communicated with the bottom of the seal leakage defect housing. The pressure balance adjustment unit is connected to the sealed cavity. Among them, the heating unit is used to heat the C 4 F 7 N / CO 2 / O 2 mixed gas, the cooling unit is used to reduce the temperature of the C 4 F 7 N / CO 2 / O 2 mixed gas, and the pressure balance adjustment unit is used to adjust the gas pressure in the sealed cavity.

2. The simulation device for seal ring leakage defects according to claim 1, characterized in that, the seal ring simulation unit includes a thin iron wire and a seal ring, the thin iron wire is embedded in the seal ring, and the seal ring communicates with the bottom of the seal ring leakage defect housing.

3. The simulation device for seal ring leakage defects according to claim 1, characterized in that, the heating unit includes a heating rod, and the heating rod is connected to the seal ring simulation unit.

4. An oxygen concentration detection device for seal ring leakage defects, characterized in that, it includes a mixed gas supply module, a pressure balance adjustment module, a seal ring leakage defect simulation module, a ventilation module and a plurality of gas on-off control structures. The seal ring leakage defect simulation module includes the seal ring leakage defect simulation device according to any one of claims 1-3. The mixed gas supply module is connected to the pressure balance adjustment module, the pressure balance adjustment module communicates with the upper surface of the seal ring leakage defect housing, the pressure balance adjustment unit is connected to the pressure balance adjustment module through a first gas on-off control structure, and the ventilation module is connected to the seal ring leakage defect simulation module through a plurality of gas on-off control structures.

5. An oxygen concentration detection method for seal ring leakage defects, characterized in that, includes the following steps: S1. Heat the C 4 F 7 N / CO 2 / O 2 mixed gas to 500 °C and record the first pressure. The C 4 F 7 N / CO 2 / O 2 mixed gas is placed in a housing with a seal leakage defect, and the housing with the seal leakage defect is placed in a closed cavity; S2, reduce the current C 4 F 7 N / CO 2 / O 2 the temperature of the mixed gas to displace the gas in the sealed cavity; S3, increase the gas pressure in the sealed cavity and record the current C 4 F 7 N and CO 2 concentration increments, and calculate the C 4 F 7 N annual leakage rate and CO 2 annual leakage rate; S4, heat the current C again 4 F 7 N / CO 2 / O 2 Heat the mixed gas to 500 °C, record the second pressure, and calculate the pressure difference between the first pressure and the second pressure; S5, based on the pressure difference, calculate the total annual leakage rate by the pressure drop method; S6. Based on the mixing ratio, the total annual leakage rate, the C 4 F 7 annual leakage rate for N years, and the CO 2 annual leakage rate, calculate the O 2 annual leakage rate, where the mixing ratio is preset.

6. The oxygen concentration detection method for seal ring leakage defects according to claim 5, characterized in that, The said O 2 The calculation formula for the annual leakage rate is as follows: In the formula, F y,O2 represents the annual leakage rate of O 2 , F y represents the total annual leakage rate, F y,C4 represents the annual leakage rate of C 4 F 7 represents the annual leakage rate of C y,CO2 N, F 2 represents the annual leakage rate of CO 4 a%, b%, and c% are the proportions of C 7 F 2 N, CO 2 , O 4 in the C 7 F 2 N / CO 2 / O mixed gas, respectively.

7. The oxygen concentration detection method for seal ring leakage defects according to claim 5, characterized in that, the calculation formula of the total annual leakage rate is: Where, F y represents the total annual leakage rate, and ΔP 500 represents the pressure difference before and after leakage at 500 °C, P r represents the rated pressure at 20 °C, and Δt represents the measurement interval time.

8. The oxygen concentration detection method for seal ring leakage defects according to claim 5, characterized in that, The currently recorded C 4 F 7 N and CO 2 concentration increments, and calculate C 4 F 7 N annual leakage rate and CO 2 The process of the annual leakage rate includes, according to C 4 F 7 N concentration increment and CO 2 concentration increment, calculate C 4 F 7 N absolute leakage rate and CO 2 absolute leakage rate; according to the said C 4 F 7 N absolute leakage rate and the said CO 2 absolute leakage rate, calculate the said C 4 F 7 N annual leakage rate and the said CO 2 annual leakage rate.

9. The oxygen concentration detection method for seal ring leakage defects according to claim 8, characterized in that, The said C 4 F 7 The N absolute leakage rate and the said CO 2 The calculation formula for the absolute leakage rate is as follows: Where, F n represents the absolute leakage rate, and ΔC n represents the increment of the concentration of the measured gas in the sealed cavity during the measurement time period Δt. n can all take C 4 F 7 N and CO 2 ; V m represents the remaining value obtained by subtracting the volume of the housing with leakage defects of the sealing ring from the effective volume of the sealed cavity; P atm represents the atmospheric pressure during the measurement period.

10. The oxygen concentration detection method for seal ring leakage defects according to claim 5, characterized in that, The said C 4 F 7 The leakage rate per N years and the said CO 2 The calculation formula for the leakage rate per year is as follows: Where, F y,n represents the annual leakage rate, C n is the gas volume ratio, and n can both take C 4 F 7 N and CO 2 ; V is the effective volume of the housing with a seal leakage defect.

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