CN115950595A - Diaphragm type oil conservator tightness checking method based on tracing method - Google Patents
Diaphragm type oil conservator tightness checking method based on tracing method Download PDFInfo
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Abstract
The invention discloses a method for checking the tightness of a diaphragm type oil conservator based on a tracing method, which comprises a diaphragm body checking test step and a flange surface leakage detection step for connecting a diaphragm; the membrane body inspection testing step comprises the following steps: nitrogen is slowly filled into the upper part of the diaphragm, so that air at the lower part of the diaphragm of the oil conservator is discharged to be static, and then standard gas is filled into the lower part of the diaphragm of the oil conservator; filling a certain amount of tracer gas into the upper part of the diaphragm, standing for 5 hours, and detecting the concentration content of the tracer gas at the upper part and the concentration content of the standard gas at the lower part of the diaphragm by adopting a mass spectrometer or an enhanced plasma chromatograph; calculating a gas volume of a lower portion of the diaphragm; calculating an absolute leak rate and a correction value of the absolute leak rate; and judging a strictness result according to the correction value. The method for checking the tightness of the diaphragm type oil conservator based on the tracing method can quickly and accurately judge the tightness of the diaphragm type oil conservator by using the tracing method.
Description
Technical Field
The invention relates to the technical field of tightness inspection of a diaphragm type oil conservator, in particular to a method for inspecting the tightness of a diaphragm type oil conservator based on a tracing method.
Background
The oil conservator is an important accessory of a large-scale oil-immersed transformer and a high-voltage reactor. GB/T6451-2015 technical parameters and requirements of oil-immersed power transformers stipulate that oil conservators should be installed on oil-immersed power transformers except for some special conditions, wherein oil aging prevention measures should be taken on transformers of 66kV and above to ensure that transformer oil is not in contact with the atmosphere, and installation of sealed oil conservators on equipment is one of key measures.
According to the division of the industrial standard JB/T6484-2016 oil conservator for transformers, the sealed oil conservator can be divided into capsule type, diaphragm type, corrugated internal oil type, corrugated external oil type, etc. The diaphragm type oil conservator is applied to a large-scale power transformer with the voltage of more than 110 kilovolts, and the main function of the diaphragm type oil conservator is that the volume of an oil tank is expanded and contracted when the environmental temperature and the transformer change, and the expansion and the contraction can be carried out in the diaphragm type oil conservator connected to the top of the oil tank. The diaphragm type oil conservator separates the atmosphere from oil by using a diaphragm, prevents the oxidation and the moisture absorption of transformer oil, and improves the insulating property of the transformer oil.
The gas leakage points possibly existing in the diaphragm type oil conservator are mainly on the diaphragm body and the flange surface connected with the diaphragm, and the common tightness inspection method for the diaphragm type oil conservator mainly comprises a simple observation method, a positive pressure/vacuum sealing test method, a relay/sensor monitoring method and the like, but the simple observation method is to observe and discover the leakage through an observation port, and under the condition that the leakage points are not large, the leakage position and the leakage rate of the diaphragm type oil conservator can be discovered only by collecting more data information for a longer time; the positive pressure/vacuum sealing test method requires that the structures and the strength of the transformer oil tank and the oil conservator can meet the requirement of vacuumizing, the tightness check can be carried out, the condition is severer, and higher precision can be achieved only when the equipment is in a constant temperature or approximately constant temperature condition; the relay/sensor monitoring method is characterized in that a special relay or sensor is additionally arranged on an oil storage cabinet, when the tightness of the oil storage cabinet is damaged, an alarm signal is automatically sent out, but the relay or sensor is complex to disassemble and re-assemble, and the accuracy requirement for detection of the relay or sensor is high.
The tracing method is a dynamic process which is difficult to identify for knowing some researched objects, one or more substances which are easy to detect are added as markers, and the process is known by tracing the markers, but the tracing method is applied to a diaphragm type oil conservator, the main leakage points of the diaphragm type oil conservator are arranged on a diaphragm body and a flange surface connected with the diaphragm, and the diaphragm is arranged in the inner layer of the diaphragm type oil conservator, when the diaphragm body leaks by using a common tracing method, when a plurality of possible leakage points exist, the precision is low, and the tightness of the diaphragm type oil conservator is difficult to judge.
The tightness checking method of the diaphragm type oil conservator based on the tracing method can quickly and accurately judge the tightness of the diaphragm type oil conservator by using the tracing method.
Disclosure of Invention
The invention aims to provide a method for checking the tightness of a diaphragm type oil conservator based on a tracing method, which can quickly and accurately judge the tightness of the diaphragm type oil conservator.
In order to achieve the aim, the method for checking the tightness of the diaphragm type oil conservator based on the tracing method comprises a diaphragm body checking test step and a flange surface leakage detection step of connecting a diaphragm;
the membrane body inspection testing step comprises the following steps:
(1) Closing the power transformer, and removing all transformer oil in the diaphragm type oil conservator; plugging a gas relay interface; all valves and pipelines except the gas circuit connected with the moisture absorber and communicated with the diaphragm type oil storage cabinet and the atmosphere are in a closed state;
(2) Dismantling the moisture absorber, arranging a flange and a temporary gas charging and discharging pipeline on a breathing pipe connector originally arranged on the moisture absorber, and respectively connecting a tracer steel cylinder containing tracer gas and a nitrogen steel cylinder containing nitrogen with the temporary gas charging and discharging pipeline;
(3) Opening a valve of an air discharge pipe interface, slowly filling nitrogen into the upper part of a diaphragm in the diaphragm type oil conservator through a temporary air filling pipeline, wherein the air filling rate is not higher than 200L/min, the air pressure of the upper part of the diaphragm is controlled not to exceed 8kPa, and when no air is discharged from the air discharge pipe interface, stopping filling air;
(4) Selecting a proper inflation connector and a clean and pollution-free air path to fill 100L of standard gas into the lower part of the diaphragm from the air release pipe connector in advance, controlling the air pressure of the upper part of the diaphragm to be not more than 8kPa during inflation, closing an air release pipe connector valve after inflation is finished, and standing for 10-20 min;
(5) Collecting 100-500 mL of air sample at the lower part of the diaphragm from the air outlet pipe joint by using a clean sampling pipeline and a sampling bag, analyzing the air sample, and recording the initial concentration C of the tracer gas test 0 ；
(6) Discharging gas at the upper part of the diaphragm through the temporary gas charging pipeline, reducing the gas pressure at the upper part of the diaphragm to the atmospheric pressure or slightly higher than the atmospheric pressure, closing an exhaust valve of the temporary pipeline, and recording the initial gas pressure before filling the tracer gas after the gas pressure is stable;
(7) Filling a certain amount of tracer gas into the upper part of the diaphragm through a temporary inflation pipeline until the air pressure of the upper part of the diaphragm is higher than the initial air pressure by about 5kPa, and then filling high-purity nitrogen into the upper part of the diaphragm to pressurize to about 12kPa;
(8) After the inflation is finished, recording the ambient temperature and the gas pressure on the upper part of the diaphragm, collecting 100-500 mL of a gas sample from the gas release pipe interface after 5h, analyzing the gas sample, and recording the concentration C1 of the tracer gas and the concentration Cs, t of the standard gas component; the average temperature T and average pressure p during the test are counted from the thermometer and manometer 17 records;
(9) Opening an exhaust valve of the temporary inflation pipeline, flushing the pipeline for 3-5 min by using gas on the upper part of the diaphragm, collecting 500mL of a gas sample on the upper part of the diaphragm, diluting the collected gas sample, measuring the content of tracer gas by using detection equipment, and recording the content Ci of the tracer gas on the upper part of the diaphragm;
(10) Calculating a gas volume of a lower portion of the diaphragm;
(11) Calculating an absolute leakage rate;
(12) Calculating a correction value for the absolute leak rate;
(13) Judging a strictness result according to the correction value; the tightness results comprise good, qualified and unqualified;
and (3) detecting the leakage of the flange surface of the connecting diaphragm, namely, wrapping the flange surface by using a plastic film while the step (8) of the checking test step of the diaphragm body is performed, standing for 5 hours, then sampling and testing the plastic film, and if trace gas or standard gas is detected, directly judging that the tightness result is unqualified.
In particular, the tracer gas is heptafluoropropane or carbon tetrafluoride.
In particular, pentafluoroethane is used as the standard gas.
In particular, the steps (8) and (9) adopt a time-of-flight mass spectrometer or an enhanced plasma chromatograph to measure the concentration of the gas tracer adopted by the tracer gas, and the test conditions of the time-of-flight mass spectrometer are as follows: ionization region pressure 3Pa, MCP voltage 2850V, accumulation of 40 spectrograms, and sampling time of about 100s; c according to mass to charge ratio m/z =151 if the gas tracer is heptafluoropropane 3 F 6 H + Carrying out quantitative calculation on the peak area of the characteristic fragment ions; the testing conditions of the enhanced plasma chromatograph are as follows: the DSP gain time of the EPD detector is 320-380 s, the pre-stage amplification factor is 4, and the secondary amplification factor is 40; the column temperature, the valve box temperature are 55 ℃, the injection port temperature is 100 ℃, and the carrier gas flow rate is 20mL/min; and if the gas tracer is carbon tetrafluoride, carrying out quantitative calculation according to the peak area of the carbon tetrafluoride component at 228nm of the optimal response signal channel in the optical wavelength module.
Specifically, the step (8) uses a time-of-flight mass spectrometer to determine the concentration of the standard gas, and the test conditions of the time-of-flight mass spectrometer are as follows: pressure of ionization region 3Pa, voltage of MCP 2700V, accumulation of 40 spectrograms, sampling time of about 100s, and C according to mass-to-charge ratio m/z =101 when the standard gas is pentafluoroethane 2 F 4 H + And (4) carrying out quantitative calculation on the peak area of the characteristic ion.
Specifically, the calculation formula for calculating the gas volume in the lower part of the diaphragm in step (10) of the diaphragm body inspection test step is as follows:
in the formula: v is the lower gas volume of the diaphragm in m 3 ；C s,o The initial concentration of the filled standard gas is measured in units of mu L/L; v s Is the volume of the filled standard gas, and the unit is L; c s,t The concentration of the calibration gas is at time t =5h, in μ L/L.
Specifically, the calculation formula for calculating the absolute leakage rate in step (11) of the step of the membrane body inspection test is as follows:
in the formula: f is the absolute leakage rate in Pa.m 3 S; Δ t is the duration of the test in units of s; Δ C is the increment of the concentration of the tracer gas in the lower part of the diaphragm within a measurement time period Δ t, and the unit is μ L/L; p is atm Is the atmospheric pressure during the measurement, in Pa;
is the gas average pressure in Pa of the upper part of the diaphragm during the test; c i The concentration of the tracer gas filled in the upper part of the diaphragm during the test is measured in mul/L.
Specifically, the calculation method of the correction value of the absolute leakage rate in the step (12) of the testing step of the body inspection of the diaphragm is a correction value converted into a medium of nitrogen when the ambient temperature is 20 ℃ according to the following calculation formula:
in the formula: f is the absolute leakage rate, F' is the absolute leakage rate correction value, and the unit is Pa.m 3 /s；M G1 The unit is the molar mass of tracer gas heptafluoropropane or carbon tetrafluoride, and the unit is g/mol;
is the average temperature of the environment during the test in K. Specifically, the step (13) of the membrane body inspection test step is specifically as follows: judging the result of the tightness according to the corrected value F 'of the absolute leakage rate, if the corrected value F' is not more than 5.0 multiplied by 10 -5 Pa·m 3 At/s, the stringency results were good; if the correction value F' is 5.0X 10 - 5 Pa·m 3 /s～5.0×10 -4 Pa·m 3 (iv) a/s range, wherein the result of tightness is qualified; if the correction value F' is greater than 5.0
10 -4 Pa·m 3 At/s, the stringency was found to be unacceptable.
Particularly, the step (1) of the inspection test step of the diaphragm body for removing all transformer oil in the diaphragm type oil conservator comprises the following specific steps: the transformer oil stored in the diaphragm oil conservator is discharged into the oil storage tank for maintenance, so that the indication scale of the oil level gauge of the diaphragm oil conservator is reduced to zero scale.
The beneficial effects of the invention are as follows:
the invention provides a method for checking the tightness of a diaphragm type oil conservator based on a tracing method. A membrane body inspection test step, namely slowly filling nitrogen into the upper part of the membrane, discharging air at the lower part of the membrane of the oil conservator to be static, and then filling standard gas into the lower part of the membrane of the oil conservator; filling a certain amount of tracer gas into the upper part of the diaphragm, standing for 5 hours, and detecting the concentration contents of the tracer gas at the upper part and the lower part of the diaphragm and the concentration content of standard gas at the lower part of the diaphragm by adopting a time-of-flight mass spectrometer or an enhanced plasma chromatograph; calculating a gas volume of a lower portion of the diaphragm; the absolute leak rate and a correction value of the absolute leak rate are calculated. The method can judge whether the diaphragm body has tightness or not according to the absolute leakage rate correction value, and the leakage detection step of the flange surface connected with the diaphragm is to wrap the diaphragm body along the flange surface by using a plastic film at the same time of the step (8) of the inspection test step of the diaphragm body and to perform sampling test on the plastic film after standing for 5 hours, if trace gas or standard gas is detected, the tightness result is directly judged to be unqualified, and the other main leakage point of the diaphragm type oil conservator can be judged during the inspection test step of the diaphragm body without omission, so that the tightness of the diaphragm type oil conservator can be quickly and accurately judged.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a structural view of a diaphragm type conservator according to an embodiment of the present invention.
In the figure: 1. a cabinet body; 2. a viewing window; 3. a diaphragm; 4. a gas release plug; 5. a breathing tube interface; 6. an oil level indicating device; 7. a water drain plug; 8. an air release pipe interface; 9. a gas relay interface; 10. an oil injection and drainage pipe interface; 11. a gas collection box; 12. a dirt collecting box; 13. a gas circuit valve; 14. nitrogen gas; 15. a tracer gas; 16. a gas flow meter; 17. and a pressure gauge.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and the scope of the present invention will be more clearly and clearly defined.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.
It is to be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like are used in a generic and descriptive sense only and not for purposes of limitation, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like are used in the generic and descriptive sense only and not for purposes of limitation, as the term is used in the generic and descriptive sense, and not for purposes of limitation, unless otherwise specified or implied, and the specific reference to a device or element is intended to be a reference to a particular element, structure, or component. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
As shown in fig. 1, in order to use a diaphragm type oil conservator of the tightness inspection method of the diaphragm type oil conservator based on the tracing method and a part of tools used in the inspection method, the tracing gas 15 adopts heptafluoropropane or carbon tetrafluoride, the standard gas adopts pentafluoroethane, the tightness inspection method of the embodiment of the invention comprises a diaphragm body inspection test step and a flange surface leakage detection step of connecting the diaphragm;
the membrane body inspection testing step comprises the following steps:
(1) Closing the power transformer, and removing all transformer oil in the diaphragm type oil conservator; plugging a gas relay interface 9; all valves and pipelines except the gas path connected with the moisture absorber and communicated with the diaphragm type oil storage cabinet and the atmosphere are in a closed state; the specific steps for removing all transformer oil in the diaphragm type oil conservator are as follows: the transformer oil stored in the diaphragm oil conservator is discharged into the oil storage tank for maintenance, so that the indication scale of the oil level gauge of the diaphragm oil conservator is reduced to zero scale.
(2) The moisture absorber is removed, a flange and a temporary gas charging and discharging pipeline are arranged on a breathing pipe connector 5 originally arranged on the moisture absorber, and a tracer steel cylinder containing tracer gas 15 and a nitrogen steel cylinder containing nitrogen 14 are respectively connected with the temporary gas charging and discharging pipeline;
(3) Opening a valve of an air discharge pipe connector 8, slowly charging nitrogen 14 into the upper part of a diaphragm 3 in the diaphragm type oil conservator through a temporary charging pipeline, wherein the charging rate is not higher than 200L/min, controlling the air pressure of the upper part of the diaphragm 3 to be not more than 8kPa, and stopping charging when no gas is discharged from the air discharge pipe connector 8;
(4) Selecting a proper inflation connector and a clean and pollution-free gas path to sequentially fill 100L of standard gas and 50L of nitrogen 14 into the lower part of the diaphragm 3 from the air release pipe connector 8, controlling the air pressure at the upper part of the diaphragm 3 not to exceed 8kPa during inflation, closing a valve of the air release pipe connector 8 after inflation is finished, and standing for 10-20 min;
(5) Collecting 100-500 mL of air sample at the lower part of the diaphragm 3 from the air outlet pipe joint 8 by using a clean sampling pipeline and a sampling bag, analyzing the air sample, and recording the initial concentration C of the test tracer gas 0 ＝0μL/L；
(6) Discharging gas at the upper part of the diaphragm 3 through a temporary gas charging pipeline, reducing the gas pressure at the upper part of the diaphragm 3 to atmospheric pressure or slightly higher than the atmospheric pressure, closing an exhaust valve of the temporary pipeline, and recording the initial gas pressure before filling the tracer gas after the gas pressure is stable;
(7) Filling a certain amount of tracer gas 15 into the upper part of the diaphragm 3 through a temporary gas filling pipeline until the gas pressure of the upper part of the diaphragm 3 is higher than the initial gas pressure by about 5kPa, and then filling high-purity nitrogen into the upper part of the diaphragm 3 to pressurize to about 12kPa;
(8) After the inflation is finished, the environmental temperature and the gas pressure on the upper part of the diaphragm 3 are recorded, after 5h, 100-500 mL of a gas sample is collected from the gas release pipe interface 8, the gas sample is analyzed, and the concentration C1=15.0 mu L/L of the tracer gas and the concentration Cs of standard gas components are recorded, wherein t =50 mu L/L; the average temperature T =299.9K and the average pressure p =11920Pa during the test were counted from the thermometer, manometer 17 records; and (8) determining the concentration of the standard gas by adopting a time-of-flight mass spectrometer, wherein the test conditions of the time-of-flight mass spectrometer are as follows: pressure of ionization region 3Pa, voltage of MCP 2700V, accumulation of 40 spectrograms, sampling time of about 100s, and C according to mass-to-charge ratio m/z =101 when the standard gas is pentafluoroethane 2 F 4 H + And (4) carrying out quantitative calculation on the peak area of the characteristic ion.
(9) Opening an exhaust valve of the temporary inflation pipeline, flushing the pipeline for 3-5 min by using gas on the upper part of the diaphragm 3, collecting 500mL of a gas sample on the upper part of the diaphragm 3, diluting the collected gas sample, measuring the content of the tracer gas 15 by using detection equipment, and recording the Ci =31700 mu L/L of the content of the tracer gas 15 on the upper part of the diaphragm 3;
and (8) and (9) determining the concentration of the gas tracer adopted by the tracer gas 15 by adopting a time-of-flight mass spectrometer or an enhanced plasma chromatograph, wherein the test conditions of the time-of-flight mass spectrometer are as follows: ionized region pressure 3Pa, MCP voltage 2850V,40 spectrogram accumulation, and sampling time of about 100s; c according to mass to charge ratio m/z =151 if the gas tracer is heptafluoropropane 3 F 6 H + Carrying out quantitative calculation on the peak area of the characteristic fragment ions; the testing conditions of the enhanced plasma chromatograph are as follows: the DSP gain time of the EPD detector is 320-380 s, the pre-stage amplification factor is 4, and the secondary amplification factor is 40; the column temperature, the valve box temperature are 55 ℃, the injection port temperature is 100 ℃, and the carrier gas flow rate is 20mL/min.
(10) Calculating the gas volume in the lower part of the membrane 3; the calculation formula for calculating the gas volume in the lower portion of the diaphragm 3 is:
in the formula: v is the lower gas volume of the diaphragm 3 in m 3 ；C s,o The initial concentration of the filled standard gas is measured in units of mu L/L; v s Is the volume of the filled standard gas, and the unit is L; c s,t The concentration of the standard gas is at time t =5h, in μ L/L.
(11) Calculating an absolute leakage rate; the calculation formula for calculating the absolute leakage rate is as follows:
in the formula: f is the absolute leakage rate in Pa.m 3 S; Δ t is the duration of the test in units of s; Δ C is the increase in concentration of tracer gas 15 in the lower part of the membrane 3 within a measurement time period Δ t, in units of μ L/L; p is atm Is the atmospheric pressure during the measurement, in Pa;
the gas average pressure in Pa of the upper part of the membrane 3 during the test; c i The upper part of the membrane 3 was filled with a concentration of trace gas 15 in μ L/L during the test.
(12) Calculating a correction value for the absolute leak rate; the calculation method for the correction value of the absolute leakage rate is the correction value converted to the environment temperature of 20 ℃ by using the nitrogen 14 as a medium according to the following calculation formula:
in the formula: f is the absolute leakage rate, F' is the absolute leakage rate correction value, and the unit is Pa.m 3 /s；M G1 The unit is the molar mass of the tracer gas 15 heptafluoropropane;
is the average temperature of the environment during the test in K.
(13) And judging a tightness result according to the correction value. The tightness results include good, qualified and unqualified; the method comprises the following specific steps:
judging the tightness result according to the absolute leakage rate correction value F ', if the correction value F' is not more than 5.0 multiplied by 10 -5 Pa·m 3 At/s, the stringency results were good; if the corrected value F' is 5.0X 10 -5 Pa·m 3 /s～5.0×10 -4 Pa·m 3 (iv) a/s range, wherein the result of tightness is qualified; if the corrected value F' is greater than 5.0X 10 -4 Pa·m 3 At/s, the stringency was found to be unacceptable.
F' =1.4 × 10 in the embodiment of the present invention -3 Pa·m 3 And/s, namely, the tightness result is unqualified, the leakage probability of the diaphragm body is judged to be high, and the problem of slight damage is really caused by checking the body part of the diaphragm.
And (3) detecting the leakage of the flange surface for connecting the diaphragm 3, namely, simultaneously wrapping the flange surface by using a plastic film in the step (8) of the diaphragm body inspection test, standing for 5 hours, then sampling and testing the plastic film, and if detecting that the tracer gas 15 or the standard gas exists, determining that the tightness result is unqualified.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, various changes or modifications may be made by the patentees within the scope of the appended claims, and within the scope of the invention, as long as they do not exceed the scope of the invention described in the claims.
Claims (10)
1. A method for checking the tightness of a diaphragm type oil conservator based on a tracing method is characterized in that: the method comprises a diaphragm body inspection test step and a flange surface leakage detection step for connecting a diaphragm;
the step of testing the diaphragm body inspection comprises the following steps:
(1) Closing the power transformer, and removing all transformer oil in the diaphragm type oil conservator; plugging a gas relay interface; all valves and pipelines except the gas circuit connected with the moisture absorber and communicated with the diaphragm type oil storage cabinet and the atmosphere are in a closed state;
(2) The method comprises the following steps of (1) removing a moisture absorber, arranging a flange and a temporary gas charging and discharging pipeline on a breathing pipe connector originally arranged on the moisture absorber, and respectively connecting a tracer steel cylinder containing tracer gas and a nitrogen steel cylinder containing nitrogen with the temporary gas charging and discharging pipeline;
(3) Opening a valve of an air discharge pipe interface 8, slowly charging nitrogen into the upper part of a diaphragm in the diaphragm type oil conservator through a temporary air charging pipeline, wherein the air charging speed is not higher than 200L/min, the air pressure of the upper part of the diaphragm is controlled not to exceed 8kPa, and when no air at the air discharge pipe interface is discharged, stopping charging air;
(4) Selecting a proper inflation connector and a clean and pollution-free air path to sequentially fill 100L of standard gas into the lower part of the membrane of the oil conservator from the air release pipe connector, controlling the air pressure at the upper part of the membrane not to exceed 8kPa during inflation, closing the valve of the air release pipe connector after inflation is finished, and standing for 10-20 min;
(5) Collecting diaphragm from air release pipe interface by clean sampling pipeline and sampling bagThe lower air sample is 100 mL-500 mL, the gas sample is analyzed, and the initial concentration C of the tracer gas test is recorded 0 ；
(6) Discharging gas at the upper part of the diaphragm through the temporary gas charging pipeline, reducing the gas pressure at the upper part of the diaphragm to the atmospheric pressure or slightly higher than the atmospheric pressure, closing an exhaust valve of the temporary pipeline, and recording the initial gas pressure before filling the tracer gas after the gas pressure is stable;
(7) Filling a certain amount of tracer gas into the upper part of the diaphragm through a temporary gas filling pipe until the gas pressure of the upper part of the diaphragm is about 5kPa higher than the initial gas pressure, and then filling high-purity nitrogen into the upper part of the diaphragm to pressurize to about 12kPa;
(8) After the inflation is finished, recording the ambient temperature and the gas pressure on the upper part of the diaphragm, collecting 100-500 mL of a gas sample from the gas release pipe interface after 5h, analyzing the gas sample, and recording the concentration C1 of the tracer gas and the concentration Cs, t of the standard gas component; the average temperature T and the average pressure p during the test are counted from the records of the thermometer and the manometer 17;
(9) Opening an exhaust valve of the temporary inflation pipeline, flushing the pipeline for 3-5 min by using gas on the upper part of the diaphragm, collecting 500mL of a gas sample on the upper part of the diaphragm, diluting the collected gas sample, measuring the content of tracer gas by using detection equipment, and recording the content Ci of the tracer gas on the upper part of the diaphragm;
(10) Calculating a gas volume of a lower portion of the diaphragm;
(11) Calculating an absolute leakage rate;
(12) Calculating a correction value for the absolute leak rate;
(13) Judging a strictness result according to the correction value; the tightness results comprise good, qualified and unqualified;
and (3) detecting the leakage of the flange surface for connecting the diaphragm, namely, wrapping the flange surface by using a plastic film while the step (8) of the checking test step of the diaphragm body, standing for 5 hours, then sampling and testing the plastic film, and directly judging that the tightness result is unqualified if tracer gas or standard gas is detected.
2. The method for checking the tightness of a membrane type conservator based on tracer method as claimed in claim 1, wherein: the tracer gas is heptafluoropropane or carbon tetrafluoride.
3. The method for checking the tightness of a membrane type oil conservator based on tracer method as claimed in claim 1, wherein: the standard gas adopts pentafluoroethane.
4. The method for checking the tightness of a membrane type oil conservator based on tracer method as claimed in claim 2, wherein: and (3) determining the concentration of the gas tracer adopted by the tracer gas by adopting a time-of-flight mass spectrometer or an enhanced plasma chromatograph in the steps (8) and (9), wherein the test conditions of the time-of-flight mass spectrometer are as follows: ionization region pressure 3Pa, MCP voltage 2850V, accumulation of 40 spectrograms, and sampling time of about 100s; c according to mass to charge ratio m/z =151 if the gas tracer is heptafluoropropane 3 F 6 H + Carrying out quantitative calculation on the peak area of the characteristic fragment ions; the testing conditions of the enhanced plasma chromatograph are as follows: the DSP gain time of the EPD detector is 320-380 s, the pre-stage amplification factor is 4, and the secondary amplification factor is 40; the column temperature and the valve box temperature are 55 ℃, the injection port temperature is 100 ℃, and the carrier gas flow rate is 20mL/min; and if the gas tracer is carbon tetrafluoride, carrying out quantitative calculation according to the peak area of the carbon tetrafluoride component at the time of 228nm of the optimal response signal channel in the optical wavelength module.
5. The method for checking the tightness of a membrane type conservator based on tracer method as claimed in claim 3, wherein: and (8) determining the concentration of the standard gas by adopting a time-of-flight mass spectrometer, wherein the test conditions of the time-of-flight mass spectrometer are as follows: pressure of an ionization region 3Pa, MCP voltage 2700V, accumulation of 40 spectrograms, sampling time of about 100s and mass-to-charge ratio m/z = 101C 2 F 4 H + And (4) carrying out quantitative calculation on the peak area of the characteristic ion.
6. The method for checking the tightness of a membrane type conservator based on tracer method as claimed in claim 1, wherein: the calculation formula for calculating the gas volume in the lower part of the diaphragm in the step (10) of the diaphragm body inspection test step is as follows:
in the formula: v is the lower gas volume of the diaphragm in m 3 ；C s,o The initial concentration of the filled standard gas is measured in the unit of mu L/L; v s Is the volume of the filled standard gas, and the unit is L; c s,t The concentration of the standard gas is at time t =5h, in μ L/L.
7. The method for checking the tightness of a membrane type oil conservator based on tracer method as claimed in claim 6, wherein: the calculation formula for calculating the absolute leakage rate in the step (11) of the diaphragm body inspection test step is as follows:
in the formula: f is the absolute leakage rate in Pa.m 3 S; Δ t is the duration of the test in units of s; Δ C is the increment of the concentration of the tracer gas in the lower part of the diaphragm within a measurement time period Δ t, and the unit is μ L/L; p is atm Is the atmospheric pressure during the measurement, in Pa;
is the gas average pressure in Pa of the upper part of the diaphragm during the test; c i The concentration of the tracer gas filled into the upper part of the diaphragm during the test was measured in. Mu.L/L.
8. The method for checking the tightness of a membrane type oil conservator based on tracer method as claimed in claim 7, wherein: the calculation method of the correction value of the absolute leakage rate in the step (12) of the diaphragm body inspection test step is a correction value which is converted to 20 ℃ of the ambient temperature by the following calculation formula and takes nitrogen as a medium:
in the formula: f is the absolute leakage rate, F' is the absolute leakage rate correction value, and the unit is Pa.m 3 /s；M G1 The unit is the molar mass of tracer gas heptafluoropropane or carbon tetrafluoride, and the unit is g/mol;
is the average temperature of the environment during the test in K.
9. The method for checking the tightness of a membrane type oil conservator based on tracer method as claimed in claim 8, wherein: the step (13) of the membrane body inspection test step is specifically as follows: judging the tightness result according to the absolute leakage rate correction value F ', if the correction value F' is not more than 5.0 multiplied by 10 -5 Pa·m 3 At/s, the stringency results were good; if the correction value F' is 5.0X 10 - 5 Pa·m 3 /s～5.0×10 -4 Pa·m 3 The range of/s, the result of strictness is qualified; if the correction value F' is greater than 5.0X 10 -4 Pa·m 3 At/s, the stringency was found to be unacceptable.
10. The method for checking the tightness of a membrane type oil conservator based on tracer method as claimed in claim 1, wherein: the step (1) of the inspection test step of the diaphragm body comprises the following specific steps of removing all transformer oil in the diaphragm type oil conservator: the transformer oil stored in the diaphragm oil conservator is discharged into the oil storage tank for maintenance, so that the indication scale of the oil level gauge of the diaphragm oil conservator is reduced to zero scale.
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