A reliable life evaluation method for in-service gas pressure regulators

Abstract

The present invention discloses a reliable life evaluation method for in-service gas pressure regulators, including the following steps: collecting sample data of in-service gas pressure regulators in cities; determining the functional failure rate of gas pressure regulator samples; correcting the initial failure years of the gas pressure regulators through accelerated tests; using the mathematical expectation formula of the failure rate model, combined with the sample failure rate of the corrected minimum in-service operating years, to determine the reliable life of the gas pressure regulator. This method can detect the in-service performance of the gas pressure regulator, quantify the service life of the gas pressure regulator, determine the overall life of the same type of gas pressure regulating facilities, and effectively support the efficient operation and maintenance of gas pressure regulating facilities. The accuracy of the failure rate in the first sampling period is improved, and the accuracy of life estimation can be improved by 5% to 10%.

Description

Technical Field

[0001] The invention relates to the field of city gas pressure regulators, in particular to a reliable life evaluation method for in-service gas pressure regulators. Background Art

[0002] As a core facility in urban gas projects, gas pressure regulators are a necessary process in gas transmission and distribution systems. During the gas supply process, the pressure regulator precisely regulates the pressure conditions to meet users' daily gas application needs. Due to factors such as environmental corrosion, gas source impurities, its own quality, and length of use, the pressure regulator may experience component failure or damage. In this damaged state, the operation of the pressure regulator will pose multiple threats to the operational safety of the urban gas transmission and distribution system. A considerable number of pressure regulators in the gas pipeline network have been in service for a long time and their service status is unknown.

[0003] At present, the fault diagnosis of gas pressure regulators is mostly carried out through state monitoring and fault warning technology to ensure the safe operation of gas pressure regulators. Patent Publication No. CN108108665A, "A safety warning method for gas pressure regulators based on multivariables", uses wavelet packet energy to analyze the energy distribution law of the first frequency band of the outlet pressure signal to determine whether the gas pressure regulator has a high-frequency fault or a low-frequency fault, and judges whether to perform a fault warning or a fault alarm on the gas pressure regulator based on the outlet pressure radar map of the gas pressure regulator. Patent Publication No. CN116701956A, "Zero-sample fault diagnosis method for gas pressure regulators based on fault attribute joint mapping", synthesizes and imitates unknown class fault samples through the fault attribute characteristics of the gas pressure regulator, and uses the synthetic samples and known class samples to train the mapping network to build a zero-sample fault diagnosis model. Patent publication number CN116817016A, "A gas pressure regulator operation fault diagnosis system based on data analysis", realizes online fault analysis of the gas pressure regulator by obtaining the pressure and flow values ​​of the gas pressure regulator in real time, and judging its working state by the length of the pressure regulator cut-off valve in the image. However, the above patent can only realize the purpose of timely discovering and locating the abnormal working state of the pressure regulator, and cannot meet the quantitative evaluation requirements of the reliable service life of similar pressure regulators in the gas system. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for evaluating the reliable life of an in-service gas pressure regulator. The evaluation method can realize the quantitative evaluation of the service life of the in-service gas pressure regulator, clarify the reliable working time of the gas pressure regulator, optimize the maintenance strategy of the gas pressure regulating facilities, reduce the frequency of unplanned maintenance, and avoid gas safety accidents and excessive emissions of temperature gases such as methane.

[0005] A reliable life evaluation method for an in-service gas pressure regulator of the present invention comprises the following steps:

[0006] Step 1: Collect sample data of gas pressure regulators in service in the city. The process is as follows:

[0007] The first step is to collect the gas pressure regulators that need to be evaluated, and collect the original performance parameters of the collected gas pressure regulator samples. The collected gas pressure regulator samples should be classified into at least 5 categories of service years and at least 5 samples within the same service years.

[0008] The second step is to count the required values ​​of the original performance parameters of the gas pressure regulator samples and detect the measured values ​​of the operating performance parameters of the gas pressure regulator samples corresponding to the original performance parameters one by one;

[0009] The third step is to classify the sample data of different types of voltage regulators in detail, grouping the voltage regulators of the same model but different service years into one category and counting their number;

[0010] Step 2: Determine the functional failure rate of the gas pressure regulator sample: For the same type of gas pressure regulator samples, compare the measured values ​​of the operating performance parameters of the pressure regulator after operation with the required values ​​of the corresponding original performance parameters. If the measured values ​​of the operating performance parameters of the pressure regulator after operation exceed the required values, it is determined that the pressure regulator has failed in this performance. Calculate the functional failure rate corresponding to each performance parameter:

[0011] Functional failure rate calculation formula: Where N(Δt i ) is the time interval Δt i The number of internal failure samples, N f (t i-1 ) is in the time interval Δt i The number of unfailed items before Δt i is the time interval (t i-1 ,t i ), in years. When t1 is the minimum service life in the sampling, the time interval of (t0, t1) is Δt1 = t1;

[0012] Step 3: Correct the initial failure period of the gas pressure regulator through accelerated testing. The steps are as follows:

[0013] The first step is to determine the stress retention rate at the initial failure of the closing pressure as the threshold of the initial failure of the pressure regulator. The specific process is: select multiple unused gas pressure regulators of the same model, place them under any temperature condition within the temperature range of [80℃, 100℃], conduct long-term accelerated testing, and take out and test the closing pressure performance and the fracture strength of the pressure regulator diaphragm of no less than 3 gas pressure regulators from the high temperature condition at intervals, construct the test time and closing pressure performance curve and the test time and stress retention rate curve, record the test time when the closing pressure fails for the first time, and use the pressure regulator diaphragm stress retention rate corresponding to this time as the threshold of the initial failure of the pressure regulator. The test cutoff time is the time when at least the closing pressure failure occurs;

[0014] The second step is to determine the initial failure age: within the temperature range of [80℃, 100℃], three groups of high temperature accelerated tests of the voltage regulator are carried out at different temperatures to determine the relationship between the stress retention rate of the voltage regulator diaphragm and time under different temperature conditions. The failure age of the voltage regulator is determined by the relationship between the stress retention rate of the voltage regulator diaphragm and time under different temperature conditions. When the stress retention rate reaches the stress retention rate threshold of the initial failure set in the first step, it is regarded as the time when the voltage regulator reaches the initial failure, which is the initial failure age t s ;

[0015] The third step is to correct the sample failure rate of the minimum sampling period: the time interval Δt1=t1 of the minimum service life in step 2 is corrected to Δt1=t1-t s , and then correct the sample failure rate of the minimum in-service operating years according to the functional failure rate calculation formula;

[0016] Step 4: Use the mathematical expectation formula of the failure rate model and the sample failure rate of the corrected minimum in-service service life to determine the reliable life of the gas pressure regulator. The specific steps are as follows:

[0017] The first step is to estimate the parameters of the failure rate model. The failure rate model is Substitute the failure rate of the sample and its corresponding service life into the model, and obtain the parameters γ and θ through regression calculation, where the sample failure rate corresponding to the minimum service life is replaced by the sample failure rate of the corrected minimum service life; t is the service life of the sample, in years, and h is the sample failure rate corresponding to the service life;

[0018] The second step is to calculate the mathematical expectation of the failure rate model, which is the mean of the reliable life of the voltage regulator before failure. The expected formula of the reliable life is: Where Γ() is the gamma function. Substituting the determined parameters γ and θ into the values, the reliable life of the gas pressure regulator is obtained.

[0019] Advantages of the present invention:

[0020] 1. The method of the present invention can quantify the service life of the gas pressure regulator through in-service performance status detection of the gas pressure regulator, determine the overall life of the same type of gas pressure regulating facilities, effectively support the efficient operation and maintenance of the gas pressure regulating facilities, and provide a basis for the health evaluation of urban gas infrastructure.

[0021] 2. The method of the present invention solves the problem of difficulty in collecting data on the initial failure of gas pressure regulating facilities, improves the accuracy of the failure rate in the first sampling period, and can improve the accuracy of life estimation by 5% to 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 It is a flow chart of a reliable life evaluation method of an in-service gas pressure regulator of the present invention;

[0024] Figure 2 This is a graph showing the change of closing pressure over time under high temperature (temperature at 90°C) test;

[0025] Figure 3 This is a graph showing the change of stress retention rate over time under high temperature (temperature at 90°C) test;

[0026] Figure 4 This is the estimation diagram of initial failure age under accelerated test. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0028] like Figure 1 As shown, a reliable life evaluation method for an in-service gas pressure regulator of the present invention comprises the following steps:

[0029] Step 1: Collect sample data of gas pressure regulators in service in the city. The process is as follows:

[0030] The first step is to collect the gas pressure regulators that need to be evaluated, and collect the original performance parameters of the collected gas pressure regulator samples. The collected gas pressure regulator samples shall be classified into no less than 5 categories of service life and no less than 5 samples within the same service life.

[0031] In the second step, required values ​​of original performance parameters of the gas pressure regulator samples are counted and actual measured values ​​of operating performance parameters of the gas pressure regulator samples corresponding to the original performance parameters are detected.

[0032] The third step is to classify the sample data of voltage regulators of different models, group voltage regulators of the same model but different years of service into one category, and count the number.

[0033] Step 2: Determine the functional failure rate of the gas pressure regulator sample: For the same type of gas pressure regulator samples, compare the measured values ​​of the operating performance parameters of the pressure regulator after operation with the required values ​​of the corresponding original performance parameters. If the measured values ​​of the operating performance parameters of the pressure regulator after operation exceed the required values, it is determined that the pressure regulator has failed in this performance. Calculate the functional failure rate corresponding to each performance parameter:

[0034] Functional failure rate calculation formula: Where N(Δt i ) is the time interval Δt i The number of internal failure samples, N f (t i-1 ) is in the time interval Δt i The number of unfailed items before Δt i is the time interval (t i-1 ,t i ) in years. When t1 is the minimum service life in the sampling, the time interval of (t0, t1) is Δt1=t1.

[0035] Step 3: Correct the initial failure age of the gas pressure regulator by accelerated testing. Since it is difficult to determine the initial failure age of the gas pressure regulator by sampling, the present invention uses an accelerated test to determine the initial failure age of the gas pressure regulator.

[0036] The first step is to determine the stress retention rate at the initial failure of the closing pressure (the stress retention rate is the diaphragm rupture strength after the test / the diaphragm rupture strength before the test) as the threshold of the initial failure of the pressure regulator. The specific process is: select multiple unused gas pressure regulators of the same type (usually not less than 30), place them under any temperature condition within the temperature range of [80℃, 100℃], and conduct a long-term accelerated test. At intervals, take out and test the closing pressure performance and the rupture strength of the pressure regulator diaphragm of not less than 3 gas pressure regulators from the high temperature condition, and construct the test time and closing pressure performance curve and the test time and stress retention rate curve. Record the test time when the closing pressure fails for the first time, and use the pressure regulator diaphragm stress retention rate corresponding to this time as the threshold of the initial failure of the pressure regulator. The test cutoff time is the time when at least the closing pressure failure occurs.

[0037] The second step is to determine the initial failure age: within the temperature range of [80℃, 100℃], conduct three groups of high-temperature accelerated tests of the voltage regulator at different temperatures to determine the relationship between the stress retention rate of the voltage regulator diaphragm and time under different temperature conditions. The failure age of the voltage regulator is determined by the relationship between the stress retention rate of the voltage regulator diaphragm and time under different temperature conditions. For details, please refer to the invention titled "A method for quickly testing the life of a gas hose and its testing system" (authorization announcement number: CN112560237 B). When the stress retention rate reaches the stress retention rate threshold of the initial failure set in the first step, it is regarded as the time when the voltage regulator reaches the initial failure, which is the initial failure age t s .

[0038] The third step is to correct the sample failure rate of the minimum sampling period: the time interval Δt1=t1 of the minimum service life in step 2 is corrected to Δt1=t1-t s , and then correct the sample failure rate of the minimum in-service operating life according to the functional failure rate calculation formula.

[0039] Step 4: Use the mathematical expectation formula of the failure rate model and the sample failure rate of the corrected minimum in-service service life to determine the reliable life of the gas pressure regulator. The specific steps are as follows:

[0040] The first step is to estimate the parameters of the failure rate model. The failure rate model is (It is an existing model, see Reliability Engineering (2nd Edition) P14, Electronic Industry Press for details), where t is the service life of the sample, in years, and h is the sample failure rate corresponding to the service life. Substitute the failure rate of the sample and its corresponding service life into the model, and obtain the parameters γ and θ through regression calculation, where the sample failure rate corresponding to the minimum service life is replaced by the sample failure rate of the corrected minimum service life.

[0041] The second step is to calculate the mathematical expectation of the failure rate model, which is the mean of the reliable life of the voltage regulator before failure. The expected formula of the reliable life is: Where Γ() is the gamma function. Substituting the determined parameters γ and θ into the values, the reliable life of the gas pressure regulator is obtained.

[0042] Example

[0043] Step 1: Take the same brand of gas pressure regulator in operation in a certain city as an example.

[0044] ① 36 samples were selected, including 8 gas pressure regulators that have been in service for 7 years, 7 that have been in service for 8 years, 10 that have been in service for 9 years, 6 that have been in service for 10 years, and 5 that have been in service for 11 years.

[0045] ②Performance requirements of gas pressure regulator: claimed closing pressure level SG is 25%, closing pressure Pb The rated outlet pressure is 2.70 kPa. 2s It is 2.16kPa, the breaking strength of the pressure regulating diaphragm is not less than 10MPa, and the breaking elongation of the pressure regulating diaphragm is not less than 400%.

[0046] ③ Count and test the performance of gas pressure regulators. Group the sampled pressure regulators by age, and use the existing gas pressure regulator characteristic test system to test the operating performance corresponding to the original performance. See Table 1 for specific results.

[0047] Table 1 Performance of sampling regulator

[0048]

[0049]

[0050]

[0051] Step 2: Determine the functional failure rate of the gas pressure regulator sample.

[0052] ① Statistics of functional failures. Taking closing pressure as the criterion, the number of failures was counted, see Table 2.

[0053] Table 2 Number of regulator failures (closing pressure)

[0054] Years in service Number of failures 7 4 8 3 9 5 10 5 11 4

[0055] ②Determine the failure rate.

[0056] use The failure rate of Table 2 is calculated, and the failure rate of voltage regulators under different working years is shown in Table 3.

[0057] Table 3 Regulator failure rate (closing pressure)

[0058] Years in service <![CDATA[Number of failures N(Δt i )]]> <![CDATA[Total N f (t i-1 )]]> <![CDATA[Time interval Δt i > <![CDATA[Failure rate h i > 7 4 36 7 0.0159 8 3 32 1 0.0938 9 5 29 1 0.1724 10 5 24 1 0.2083 11 4 19 1 0.2105

[0059] Step 3: Correct the initial failure age of the gas pressure regulator through accelerated testing.

[0060] The stress retention rate at the time of the initial failure of the closing pressure (the stress retention rate is the diaphragm rupture strength after the test / the diaphragm rupture strength before the test) is determined as the threshold of the initial failure of the pressure regulator. The specific process is: 30 unused gas pressure regulators of the same model are selected, placed under high temperature conditions, and subjected to long-term accelerated testing, and at intervals, no less than 3 gas pressure regulators are taken out from the high temperature conditions and tested for the closing pressure performance and the rupture strength of the pressure regulator diaphragm, and the test time and closing pressure performance curves and the test time and stress retention rate curves are constructed. The test time at the initial failure of the closing pressure is recorded, and the stress retention rate of the pressure regulator diaphragm corresponding to this time is used as the threshold of the initial failure of the pressure regulator. The test cutoff time is the time when at least the closing pressure failure occurs.

[0061] ① By Figure 2 It can be seen that on the 8th day of the high-temperature 90℃ test, the closing pressure function of the voltage regulator showed initial failure. At this time, the diaphragm stress retention rate decreased during the whole process and reached 0.88 on the 8th day.

[0062] ② Long-term tests were carried out at 100℃, 90℃ and 80℃. When the stress retention rate reached the initial failure threshold of 0.88, the analysis results were shown in Figure 4 As can be seen from the figure, the working time with higher frequency in the calculation results is between [6.3,6.4], so the initial failure period is determined to be 6.3 years. If the sampled gas pressure regulator has no failure, this data can be used as the trouble-free operation period of this type of gas pressure regulator.

[0063] ③ Failure rate correction.

[0064] The sample failure rate of the corrected minimum sampling period is shown in Table 4.

[0065] Table 4 Regulator failure rate (closing pressure)

[0066]

[0067] Step 4: Use the mathematical expectation of the failure model and the corrected failure rate to determine the reliable life of the gas pressure regulator.

[0068] Substitute the failure data in Table 4 into We obtain γ=3.096、θ=10.953. Substitute the parameters to calculate the mathematical expectation of the working life before failure E(t) = 9.80 years.

[0069] Substituting the failure data in Table 2, we can obtain γ = 4.566, θ = 11.732. Substituting the parameters into the expected time before failure, E(t) = 10.71 years, with a deviation of 8.6% from the corrected value.

[0070] Through the above analysis, it can be seen that the reliable life of the sampling gas pressure regulator is 9.8 years. The operating reliability of the gas pressure regulator that exceeds 9.8 years is low and needs to be replaced.

[0071] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A reliable life evaluation method for an in-service gas pressure regulator, characterized in that The following steps are involved: Step 1: Collect sample data of gas pressure regulators in service in the city. The process is as follows: The first step is to collect the gas pressure regulators that need to be evaluated, and collect the original performance parameters of the collected gas pressure regulator samples. The collected gas pressure regulator samples should be classified into at least 5 categories of service years and at least 5 samples within the same service years. The second step is to count the required values ​​of the original performance parameters of the gas pressure regulator samples and detect the measured values ​​of the operating performance parameters of the gas pressure regulator samples corresponding to the original performance parameters one by one; The third step is to classify the sample data of different types of voltage regulators in detail, grouping the voltage regulators of the same model but different service years into one category and counting their number; Step 2: Determine the functional failure rate of the gas pressure regulator sample: For the same type of gas pressure regulator samples, compare the measured values ​​of the operating performance parameters of the pressure regulator after operation with the required values ​​of the corresponding original performance parameters. If the measured values ​​of the operating performance parameters of the pressure regulator after operation exceed the required values, it is determined that the pressure regulator has failed in this performance. Calculate the functional failure rate corresponding to each performance parameter: Functional failure rate calculation formula: Where N(Δt i ) is the time interval Δt i The number of internal failure samples, N f (t i-1 ) is in the time interval Δt i The number of unfailed items before Δt i is the time interval (t i-1 ,t i ), in years. When t1 is the minimum service life in the sampling, the time interval of (t0, t1) is Δt1 = t1; Step 3: Correct the initial failure period of the gas pressure regulator through accelerated testing. The steps are as follows: The first step is to determine the stress retention rate at the initial failure of the closing pressure as the threshold of the initial failure of the pressure regulator. The specific process is: select multiple unused gas pressure regulators of the same model, place them under any temperature condition within the temperature range of [80℃, 100℃], conduct long-term accelerated testing, and take out and test the closing pressure performance and the fracture strength of the pressure regulator diaphragm of no less than 3 gas pressure regulators from the high temperature condition at intervals, construct the test time and closing pressure performance curve and the test time and stress retention rate curve, record the test time when the closing pressure fails for the first time, and use the pressure regulator diaphragm stress retention rate corresponding to this time as the threshold of the initial failure of the pressure regulator. The test cutoff time is the time when at least the closing pressure failure occurs; The second step is to determine the initial failure age: within the temperature range of [80℃, 100℃], three groups of high temperature accelerated tests of the voltage regulator are carried out at different temperatures to determine the relationship between the stress retention rate of the voltage regulator diaphragm and time under different temperature conditions. The failure age of the voltage regulator is determined by the relationship between the stress retention rate of the voltage regulator diaphragm and time under different temperature conditions. When the stress retention rate reaches the stress retention rate threshold of the initial failure set in the first step, it is regarded as the time when the voltage regulator reaches the initial failure, which is the initial failure age t s ; The third step is to correct the sample failure rate of the minimum sampling period: the time interval Δt1=t1 of the minimum service life in step 2 is corrected to Δt1=t1-t s , and then correct the sample failure rate of the minimum in-service operating years according to the functional failure rate calculation formula; Step 4: Use the mathematical expectation formula of the failure rate model and the sample failure rate of the corrected minimum in-service service life to determine the reliable life of the gas pressure regulator. The specific steps are as follows: The first step is to estimate the parameters of the failure rate model. The failure rate model is Substitute the failure rate of the sample and its corresponding service life into the model, and obtain the parameters γ and θ through regression calculation, where the sample failure rate corresponding to the minimum service life is replaced by the sample failure rate of the corrected minimum service life; t is the service life of the sample, in years, and h is the sample failure rate corresponding to the service life; The second step is to calculate the mathematical expectation of the failure rate model, which is the mean of the reliable life of the voltage regulator before failure. The expected formula of the reliable life is: Where Γ() is the gamma function. Substituting the determined parameters γ and θ into the values, the reliable life of the gas pressure regulator is obtained.

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