A method for online verification of natural gas measurement standard device

Abstract

The invention discloses a method for online verification of a natural gas measurement standard device, which relates to the field of natural gas measurement technology, and aims to solve the problem that the quality monitoring means can effectively detect the stability state of the accuracy of the measurement standard device, but inevitably there is hysteresis, and the performance change of the measurement standard cannot be grasped in the first time. The key points of the technical solution are as follows: S1: calculation of the center line; A1: calculation of the indication error; A2: calculation of the center line; S2: setting the control limit; S3: calculation of the early warning limit; B1: data discrimination and selection; B2: dynamic early warning calculation; B3: calculation of the control limit; B4: early warning limit of multiple standard tables; S4: over-limit judgment; C1: selection of early warning limit and control limit; C2: over-limit judgment of single standard table; C3: over-limit judgment of multiple standard tables. The effect of accurate measurement and calculation, measurement and calculation of multiple types of standard tables and convenient calculation of over-limit is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas metering, and in particular to a method for online verification of a natural gas metering standard device. Background Art

[0002] In order to ensure the accurate transfer of measurement standard values, domestic natural gas calibration institutions regularly conduct repeatability stability tests, periodic inspections and other quality monitoring work on each set of measurement standard devices. If the above tests find that the measurement standard device has a deviation in the value, in addition to eliminating the deviation, it is also necessary to evaluate the impact of the value transfer and conduct quality traceability when necessary.

[0003] The above-mentioned existing technical solutions have the following defects: the quality monitoring means can effectively detect the stability state of the accuracy of the measurement standard device, but there is inevitably a lag, and it is impossible to grasp the changes in the performance of the measurement standard in the first time. The user unit needs to reasonably formulate the measurement standard quality monitoring test cycle based on the risk of device value failure and test cost. Once a deviation is found, the quality traceability of the value transfer results within the cycle is required. If the value transfer involves other calibration agencies, the impact will be more complicated. Summary of the invention

[0004] The purpose of the present invention is to provide a method for online verification of a natural gas measurement standard device, which can perform online real-time verification on a natural gas measurement standard device, realize quality control of the measurement standard, and ensure accurate and reliable transmission of natural gas quantity values.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for online verification of a natural gas measurement standard device, the steps of which are as follows:

[0007] S1: Calculation of center line: Calculate the indication error and repeatability at a flow point to obtain the indication error of the flow point. Calculate the center line of the standard table based on the obtained indication error to obtain the average value of multiple groups of indication errors, and set the average value of multiple groups of indication errors as the center line value;

[0008] A1: Calculation of indication error: The indication error of a flow point is the average value of the indication error of each test corresponding to the flow point. This indication error is the indication error of the flow between the standard table and the fixed check table. The flow point repeatability is calculated based on the indication error. The repeatability of the test result of a flow point is the Bessel formula of the indication error of each test corresponding to the flow point:

[0009] ;

[0010] Where: Er is the repeatability of the test result of a flow point,

[0011] Ei is the indication error of the ith calibration,

[0012] is the average value of n test results;

[0013] A2: Calculation of center line: For each standard meter, the indication error of each flow point in a calibration is taken as a basic unit, and 10 basic unit data constitute a subgroup. The average value of each subgroup is , take 10 subgroups The average value is the center line. When the standard table or check table is recalibrated, the average value of the first 10 subgroups is taken as the new center line. When the number of subgroups is less than 10 and the conditions for calculating the center line are not met, the center line is taken as 0.

[0014] S2: Set control limits: Set control limits for each standard meter pipeline separately, and set the control limits for each standard meter pipeline preliminarily;

[0015] S3: Calculation of warning limit: one-to-one verification of the flow meter's percentage, flow point, number of times, pipeline combination and indication error type parameters, and identification and selection of data, and calculation of the warning limit based on the selected values;

[0016] B1: Data identification and selection: The combination of standard table and check table pipeline used in one calibration is 1 check table + n standard tables. The warning limit is calculated based on the case of only 1 check table + 1 standard table. The warning limit of the corresponding standard table is calculated based on the dynamic warning calculation result for the two flow intervals above and below the boundary flow of the standard table.

[0017] B2: Dynamic early warning calculation: The standard meter boundary flow is 20% of the maximum flow. It is divided into two intervals according to the boundary flow. The control limits are set for the two intervals respectively. The early warning limit is calculated using the mean value-standard deviation control chart. For each standard meter, the indication error of each flow point is taken as a basic unit. 10 basic unit data constitute a subgroup. When the mean value-standard deviation control chart is used, the calculated statistical control quantity is: the average value of each subgroup , the standard deviation s of each subgroup, the mean value of each subgroup and the average of the standard deviations of the subgroups ;

[0018] B3: Calculation of control limits: Calculate the center line (CL), upper warning limit (UCL), lower warning limit (LCL), mean control chart - The center line CL, the upper warning limit UCL, and the lower warning limit LCL are: CL= ;

[0019] UCL= +A3 ;

[0020] LCL = A3 ;

[0021] Let , where d represents the half-width of the warning limit;

[0022] The average value control chart - S chart, with its center line CL, upper control limit UCL, and lower control limit LCL, are respectively: CL = ;

[0023] UCL = B5 ;

[0024] LCL = B6 ;

[0025] B4: Warning limit of multi-channel standard meter: Regarding the calculation of the warning limit of the multi-channel standard meter, since the calibers and flow ranges are the same, calculate the warning limit for each channel according to the single-channel standard meter. When the multi-channel standard meters are used together, the multi-channel warning limit is the combined calculation of multiple single-channel warning limits;

[0026] S4: Overlimit judgment. Under the known conditions of the warning limit and control limit, perform overlimit judgment on the indication error of each test result at each flow point during real-time calibration;

[0027] C1: Selection of warning limit and control limit: For each channel of the standard meter, when the warning limit is greater than the control limit, use the control limit; when the warning limit is less than or equal to the control limit, use the warning limit;

[0028] C2: Overlimit judgment for single-channel standard meter. For the case of using a single-channel standard meter, compare the indication error - center line of the verification table at each flow point during each calibration with the warning limit and control limit:

[0029] When the verification error - center line is greater than UCL or the verification error - center line is less than LCL, it is prompted that the warning limit is exceeded,

[0030] When the deviation between the verification error and the center line is greater than the uncertainty of the standard meter, it is prompted that the control limit is exceeded, and then stop using this channel of the standard meter;

[0031] C3: Overlimit judgment for multi-channel standard meter. For each single-channel standard meter, let , where d represents the half-width of the warning limit of the single-channel standard meter. When calibrating the flowmeter with n-channel standard meters combined, the half-width of the warning limit of the i-th channel standard meter is di, and the flow of this standard meter when calibrating a certain flow point is qi. Then, after combining n-channel standard meters, it should satisfy that the verification error - center line < dn, where: ;

[0032] When |Verification error-center line|>dn, it indicates that the warning limit is exceeded;

[0033] When the verification error-center line is greater than the uncertainty of the standard table, it indicates that the control limit is exceeded.

[0034] Furthermore, each standard meter pipeline of S2 sets a control limit as the standard meter uncertainty.

[0035] Furthermore, the control limit of each standard meter pipeline in S2 is initially set to the standard meter uncertainty.

[0036] In summary, the beneficial technical effects of the present invention are:

[0037] 1. The method for online verification of the natural gas measurement standard device is used to conduct online real-time verification of the natural gas measurement standard device, realize the quality control of the measurement standard, ensure the accurate and reliable transmission of the natural gas value, and produce the effect of accurate measurement and calculation;

[0038] 2. The online verification method of the natural gas measurement standard device uses the detection method of the early warning limit of multiple standard meters. According to the same caliber and flow range, the early warning limit of each channel is calculated according to the single-channel standard meter, producing the effect of multiple types of standard meter measurement;

[0039] 3. The online verification method of the natural gas metering standard device, the over-limit judgment of a single-channel standard meter and the over-limit judgment of multiple-channel standard meters facilitate the overall calculation of different over-limit states according to different situations, thus producing an effect of facilitating the calculation of over-limits. DETAILED DESCRIPTION

[0040] The method of the present invention is described in further detail below.

[0041] A method for online verification of a natural gas measurement standard device, the steps of which are as follows:

[0042] S1: Calculation of center line: Calculate the indication error and repeatability at a flow point to obtain the indication error of the flow point. Calculate the center line of the standard table based on the obtained indication error to obtain the average value of multiple groups of indication errors, and set the average value of multiple groups of indication errors as the center line value;

[0043] A1: Calculation of indication error: The indication error of a flow point is the average value of the indication error of each test (n times) corresponding to the flow point, and the flow point repeatability is calculated based on the indication error. The repeatability of the test result of a flow point is the Bessel formula of the indication error of each test (n times) corresponding to the flow point:

[0044] (1)

[0045] Where: Er is the repeatability of the test result of a flow point,

[0046] Ei is the indication error of the ith calibration,

[0047] is the average value of n test results;

[0048] A2: Calculation of center line: For each standard meter, the indication error of each flow point in a calibration is taken as a basic unit, and 10 basic unit data constitute a subgroup. The average value of each subgroup is , take 10 subgroups The average value is the center line. When the standard table or check table is recalibrated, the average value of the first 10 subgroups is taken as the new center line. When the number of subgroups is less than 10 and the conditions for calculating the center line are not met, the center line is taken as 0.

[0049] S2: Set control limits: Set control limits for each standard meter pipeline separately, and set the initial control limits for each standard meter pipeline. Set control limits for each standard meter pipeline separately. ±0.29%, the control limit of each standard meter pipeline is initially set to the standard meter uncertainty ±0.23%, control limit refers to the control range specified when implementing quality control procedures for analytical tests. In environmental monitoring, it is generally stipulated that the range within which 99.7% of all test results fall is the quality control range, i.e., the control limit;

[0050] S3: Calculation of warning limit: one-to-one verification of the flow meter's percentage, flow point, number of times, pipeline combination and indication error type parameters, and identification and selection of data, and calculation of the warning limit based on the selected values;

[0051] B1: Data identification and selection: All data corresponding to a flow point are grouped together. Each number corresponds to a standard table and a check table pipeline combination used for a calibration, which is 1 check table + n standard tables. The case of only 1 check table + 1 standard table is selected to calculate the warning limit. The dynamic warning calculation result is used as the warning limit of the corresponding standard table for the two flow intervals above and below the boundary flow of the standard table;

[0052] B2: Dynamic early warning calculation: The standard meter boundary flow is 20% of the maximum flow, and it is divided into two intervals according to the boundary flow. The average value-standard deviation control chart is used to calculate the early warning limit. For each standard meter, the indication error of each flow point is taken as a basic unit, and 10 basic unit data constitute a subgroup. When the average value-standard deviation control chart is used, the calculated statistical control quantity is: the average value of each subgroup , the standard deviation s of each subgroup, the mean value of each subgroup and the average of the standard deviations of each subgroup ;

[0053] B3: Calculation of control limits: Calculate the center line (CL), upper warning limit (UCL), and lower warning limit (LCL) for each control chart. For the mean control chart - chart, its center line CL (fixed), upper warning limit UCL, and lower warning limit LCL are respectively: CL = ;

[0054] UCL = + A3 ;

[0055] LCL = A3 ;

[0056] Let , where d represents the half-width of the warning limit

[0057] For the mean control chart - S chart, its center line CL, upper control limit UCL, and lower control limit LCL are respectively: CL = ;

[0058] UCL = B5 ;

[0059] LCL = B6 ,

[0060] The values of A3, B5, and B6 change according to the actual situation, so the specific values are not listed for display, and the values of the coefficients are calculated according to the above formulas;

[0061] B4: Warning limits for multi-channel standard meters: Involves the calculation of warning limits for multi-channel standard meters. Since their calibers and flow ranges are the same, calculate the warning limits for each channel according to the single-channel standard meter;

[0062] S4: Overlimit judgment. Under the known conditions of warning limits and control limits, perform overlimit judgment on the indication errors of each test result at each flow point during real-time calibration;

[0063] C1: Selection of warning limits and control limits: The warning limit is the warning limit, and the control limit is the control limit. The concepts should be unified. For each standard meter, when the warning limit is greater than the control limit, use the control limit; when the warning limit is less than or equal to the control limit, use the warning limit;

[0064] C2: Overlimit judgment for single-channel standard meters. For the case of using a single-channel standard meter, compare the indication error - center line of the verification table at each flow point during each calibration with the warning limit and control limit:

[0065] When the verification error - center line > UCL or the verification error - center line < LCL, it indicates exceeding the warning limit,

[0066] When the deviation between the verification error and the center line is greater than 0.23%, it is prompted that the control limit is exceeded, and then the standard meter for this path is stopped from being used;

[0067] C3: Judgment of multi-path standard meter overrun. For each single-path standard meter, let , where d represents the half-width of the warning limit of the single-path standard meter. When calibrating the flowmeter with an n-path standard meter combination, the half-width of the warning limit of the i-th path standard meter is di. When calibrating a certain flow point, the flow of this standard meter is qi. Then, after the n-path standard meter combination, it should satisfy that the verification error - center line < dn, where: ;

[0068] When |verification error - center line| > dn, it is prompted that the warning limit is exceeded;

[0069] When the deviation between the verification error and the center line is greater than 0.23%, it is prompted that the control limit is exceeded.

[0070] The embodiments of this specific implementation manner are all preferred embodiments of the present invention. The protection scope of the present invention is not limited hereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for online verification of a natural gas measurement standard device, characterized in that: The steps are as follows: S1: Calculation of center line: Calculate the indication error and repeatability at a flow point to obtain the indication error of the flow point. Calculate the center line of the standard table based on the obtained indication error to obtain the average value of multiple groups of indication errors, and set the average value of multiple groups of indication errors as the center line value; A1: Calculation of indication error: The indication error of a flow point is the average value of the indication error of each test corresponding to the flow point. This indication error is the indication error of the flow between the standard table and the fixed check table. The flow point repeatability is calculated based on the indication error. The repeatability of the test result of a flow point is the Bessel formula of the indication error of each test corresponding to the flow point: ； Where: Er is the repeatability of the calibration result of a flow point, Ei is the indication error of the ith calibration, is the average value of n test results; A2: Calculation of center line: For each standard meter, the indication error of each flow point in a calibration is taken as a basic unit, and 10 basic unit data constitute a subgroup. The average value of each subgroup is , take 10 subgroups The average value is the center line. When the standard table or check table is recalibrated, the average value of the first 10 subgroups is taken as the new center line. When the number of subgroups is less than 10 and the conditions for calculating the center line are not met, the center line is taken as 0. S2: Set control limits: Set control limits for each standard meter pipeline separately, and set the control limits for each standard meter pipeline preliminarily; S3: Calculation of warning limit: one-to-one verification of the flow meter's percentage, flow point, number of times, pipeline combination and indication error type parameters, and identification and selection of data, and calculation of the warning limit based on the selected values; B1: Data identification and selection: The combination of standard table and check table pipeline used in one calibration is 1 check table + n standard tables. The warning limit is calculated based on the case of only 1 check table + 1 standard table. The warning limit of the corresponding standard table is calculated based on the dynamic warning calculation result for the two flow intervals above and below the boundary flow of the standard table. B2: Dynamic early warning calculation: The standard meter boundary flow is 20% of the maximum flow. It is divided into two intervals according to the boundary flow. The control limits are set for the two intervals respectively. The early warning limit is calculated using the mean value-standard deviation control chart. For each standard meter, the indication error of each flow point is taken as a basic unit. 10 basic unit data constitute a subgroup. When the mean value-standard deviation control chart is used, the calculated statistical control quantity is: the average value of each subgroup , the standard deviation s of each subgroup, the mean value of each subgroup and the average of the standard deviations of the subgroups ; B3: Calculation of control limits: Calculate the center line (CL), upper warning limit (UCL), lower warning limit (LCL) and mean value control chart of each control chart. The center line CL, the upper warning limit UCL, and the lower warning limit LCL are: CL= ; <h2 style=";text-align:left;direction:ltr">UCL=<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> +A3<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> ; LCL= A3 ; make , d represents the half width of the warning limit; Mean value control chart - S chart, the center line CL, upper control limit UCL, and lower control limit LCL are: CL = ; UCL=B5 ; LCL=B6 ; B4: Warning limit of multiple standard tables: involves the calculation of warning limits of multiple standard tables. Because they have the same caliber and flow range, the warning limit of each channel is calculated according to the single-channel standard table. When multiple standard tables are used together, the multi-channel warning limit is calculated by combining multiple single-channel warning limits. S4: Over-limit judgment: Under the known warning limit and control limit, the indication error of each test result at each flow point during real-time calibration is judged as over-limit; C1: Selection of warning limit and control limit: For each standard table, when the warning limit is greater than the control limit, use the control limit; when the warning limit is less than or equal to the control limit, use the warning limit; C2: Judgment of over-limit of single-channel standard table. For the case of using a single-channel standard table, compare the indication error-center line of the table with the warning limit and control limit at each flow point during each calibration: When the verification error-center line is greater than UCL or the verification error-center line is less than LCL, it indicates that the warning limit is exceeded. When the deviation between the verification error and the center line is greater than the uncertainty of the standard table, it is indicated that the control limit is exceeded, and the use of the standard table should be stopped; C3: Multichannel standard meter overlimit judgment, for each single-channel standard meter , where d represents the half-width of the warning limit of the single-channel standard meter. When the n-channel standard meter is combined to calibrate the flowmeter, the half-width of the warning limit of the i-th channel standard meter is di. When calibrating a certain flow point, the flow of this standard meter is qi. Then, after the n-channel standard meter is combined, it should satisfy the verification error - center line < dn, where: ; When |Verification error-center line|>dn, it indicates that the warning limit is exceeded; When the verification error-center line is greater than the uncertainty of the standard table, it indicates that the control limit is exceeded.

2. The method for online verification of a natural gas measurement standard device according to claim 1, characterized in that: The control limits of each standard table pipeline of S2 are respectively set as the standard table uncertainty.

3. The method for online verification of a natural gas measurement standard device according to claim 1, characterized in that: The control limit of each standard meter pipeline in S2 is initially set to the standard meter uncertainty.

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