Natural gas composition content calculation and corresponding uncertainty evaluation method and system

Abstract

The invention provides a natural gas composition content calculation and corresponding uncertainty evaluation method and system, and belongs to the technical field of natural gas. Calculating the original mole fraction of the sample by adopting a successive normalization method, and performing nonlinear error correction on the original mole fraction to obtain a first mole fraction; sequentially performing data integrity verification, individual component compliance verification and logic correlation analysis of isomeride and carbon number distribution on the original mole fraction to obtain a comprehensive quality evaluation result; and calculating the composition uncertainty of the first mole fraction after the comprehensive quality evaluation result passes. According to the method, accurate, standard, rapid, simple and convenient calculation and evaluation of the natural gas composition content and the uncertainty are realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of natural gas, and particularly relates to a method and system for calculating the composition content of natural gas and evaluating the corresponding uncertainty. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] With the rapid growth of natural gas production and sales, there are a large number of trade settlement links in the production, transportation and sales of natural gas. At present, the volume of natural gas under standard state is mainly used as trade settlement data, and the trade data of both parties is calculated by combining the volume unit price of natural gas. The uncertainty evaluation result of volume measurement is used as the symbol of the accuracy of volume measurement. The composition analysis and uncertainty evaluation method of natural gas are the basic data used in the volume calculation process of natural gas trade settlement, and are crucial to the economic interests of all parties to the natural gas trade.

[0004] The composition analysis and uncertainty evaluation process of natural gas involves many complex methods and data, and the uncertainty evaluation process is relatively complex. In addition, the existing method has the problem that the checking method of the calculation result of the original mole fraction is not comprehensive in the calculation process of the mole fraction. Generally, only whether the total value of the original mole fraction meets the standard is checked, which may cause the problem that the detection result does not meet the composition content rule of natural gas samples in nature. SUMMARY

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a method and system for calculating the composition content of natural gas and evaluating the corresponding uncertainty, which standardizes and computerizes the composition analysis and uncertainty evaluation process of natural gas, provides a standard, fast and simple method for calculating and evaluating the composition content and uncertainty of natural gas for the related working process, and solves the problems of complicated steps and low efficiency in the calculation process, thereby improving the accuracy of the evaluation method.

[0006] To achieve the above object, one or more embodiments of the present application provide the following technical solutions: In a first aspect, the present application discloses a method for calculating the composition content of natural gas and evaluating the corresponding uncertainty, comprising: obtaining a natural gas sample to be detected; calculating the original mole fraction of the sample by using a successive normalization method, and correcting the original mole fraction by a non-linear error to obtain a first mole fraction; performing data integrity checking, individual component conformity checking and logical correlation analysis of isomers and carbon number distribution on the original mole fraction in sequence to obtain a comprehensive quality evaluation result; The first molar fraction is calculated to obtain a composition uncertainty after passing the comprehensive quality evaluation result.

[0007] In a second aspect, the application discloses a natural gas composition content calculation and corresponding uncertainty evaluation system, comprising: A data acquisition module is configured to acquire a natural gas sample to be detected. A molar fraction calculation module is configured to calculate an original molar fraction of the sample by using a successive normalization method, and correct a non-linear error of the original molar fraction to obtain a first molar fraction. A quality inspection module is configured to sequentially perform data integrity verification, individual component conformity verification, and logical correlation analysis of isomers and carbon number distribution on the original molar fraction to obtain a comprehensive quality evaluation result. An uncertainty calculation module is configured to calculate a composition uncertainty of the first molar fraction after passing the comprehensive quality evaluation result.

[0008] In a third aspect, the application discloses an electronic device, comprising a memory and a processor, and computer instructions stored in the memory and running on the processor, when the computer instructions are run by the processor, the steps of the natural gas composition content calculation and corresponding uncertainty evaluation method are completed.

[0009] In a fourth aspect, the application discloses a computer readable storage medium for storing computer instructions, when the computer instructions are executed by the processor, the steps of the natural gas composition content calculation and corresponding uncertainty evaluation method are completed.

[0010] In a fifth aspect, the application further provides a computer program product, which comprises executable instructions stored in a computer readable storage medium; wherein when the processor of the electronic device reads the executable instructions from the computer readable storage medium and executes the executable instructions, the natural gas composition content calculation and corresponding uncertainty evaluation method is realized.

[0011] Compared with the prior art, the application has the following beneficial effects: The application finally obtains the content calculation result of the natural gas composition analysis and the uncertainty evaluation result of the component content by determining the instrument analysis mode, calculating the component content molar percentage, instrument detection repeatability, normalization, non-linear error correction and other links, and standardizes and computer programs the natural gas composition analysis and uncertainty evaluation process, thereby providing a standard, fast and simple natural gas composition content and uncertainty calculation and evaluation method for related working processes.

[0012] The application checks and judges the original mole fraction by using the intelligent checking system of multi-level and weighted decision, ensures that the original mole fraction calculated by the peak area mole fraction detected by the instrument meets the basic requirements of the standard, meets the natural gas sample composition content distribution law existing in nature, and avoids unreasonable detection results.

[0013] Advantages of the additional aspects of the application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0014] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application, explain the application, and do not limit the application.

[0015] Figure 1 The natural gas composition content calculation and corresponding uncertainty evaluation method flowchart described in embodiment one of the application. DETAILED DESCRIPTION

[0016] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs.

[0017] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the application.

[0018] In the case of no conflict, the embodiments in the application and the features in the embodiments can be combined with each other.

[0019] Embodiment one In one or more embodiments, a natural gas composition content calculation and corresponding uncertainty evaluation method is disclosed, including instrument analysis mode determination, component content mole percentage calculation, instrument detection repeatability, normalization, nonlinear error correction, etc. Each link finally obtains the content calculation result of natural gas composition analysis, and the uncertainty evaluation result of each component content, such as Figure 1 As shown, the method comprises the following steps: Step S0, determining the instrument analysis mode: using the second type of analysis mode of the online gas chromatograph.

[0020] It should be understood that the online gas chromatograph adopts single-point correction method to analyze the composition content of natural gas, so most of them are the second type of analysis mode. The characteristics of this analysis mode are that one or more bottles of gas standard substances are equipped for daily calibration, and the relative response factor of each component is calculated by the content given by the gas standard substance and the peak area data of each component.

[0021] Step S1, obtaining a natural gas sample to be detected.

[0022] The sample inlet of the online gas chromatograph is directly connected to the natural gas pipeline. After being reduced to about 0.2 MPa by a pressure reducing valve, most of the dust, water, oil and other impurities are removed by a filter, and then the sample is introduced into the sample inlet of the chromatograph for analysis.

[0023] Step S2, calculating the original mole fraction of the sample by using the successive normalization method, and correcting the non-linear error of the original mole fraction to obtain the first mole fraction.

[0024] Step S2-1, calculating the original mole fraction of the sample by using the successive normalization method, as follows: (1) Wherein: is the original mole fraction of the i component, is the relative response factor of the i component after daily calibration, is the peak area detection result of the i component of the sample.

[0025] Since the sample of the online gas chromatograph is in a flowing state, multiple repeated analysis cannot be performed, therefore, the successive normalization method can be used, but the mean normalization method cannot be used.

[0026] Step S2-2, for the second type of analysis mode used by the online gas chromatograph, a certain non-linear error will be introduced, if the instrument carries out performance evaluation according to the standard, the non-linear error can be corrected, then the original mole fraction of each component should be corrected to obtain the first mole fraction by formula (2): (2) Wherein: is the original mole fraction of the i component, i is the non-linear error corrected original mole fraction of the i component, The value of is determined by the degree of the assumed linear response function of the true analysis function zero intercept deviation of the analysis instrument.

[0027] Step S2-3, for all components of the sample, the total value of the original mole fraction should be between 99% and 101%, generally the original mole fraction needs to be calculated by normalization, and the normalization calculation of each component is completed by formula (3): (3) wherein: is the normalized mole fraction of the i component.

[0028] Step S3, sequentially performing data integrity check, individual component compliance check and isomer and carbon number distribution logical correlation analysis on the original mole fraction, to obtain comprehensive quality evaluation results.

[0029] Step S3-1, basic integrity check on the original mole fraction of each component: Performing summation verification, calculating the total sum of the mole fractions of all components, and the result must strictly fall within the preset threshold interval, which is set to a closed interval of (99%, 101%) in this embodiment. If the summation verification fails, the system will directly determine that the analysis is invalid and immediately mark it as "data integrity error".

[0030] Step S3-2, individual component compliance check. After passing the integrity check, the algorithm enters the second layer, and the threshold boundary analysis of the key components is performed, and the measured values of each component are compared one by one to see if they fall within the "healthy interval" as shown in Table 1. Any value outside the range will be automatically marked, and different risk levels will be assigned according to the degree of deviation (such as slight deviation, serious deviation). When the deviation exceeds 2% of the limit value, it is considered as slight deviation, and when the deviation exceeds 5% of the limit value, it is considered as serious deviation.

[0031] It should be understood that the key components include N2, CO2, C1, C2, C3, C4, C5 and C6.

[0032] Table 1 Component or property limit value

[0033] Step S3-3, isomer and carbon number distribution check.

[0034] Among them, the isomer ratio check includes: calculating the ratio of the key isomer pair, and this embodiment calculates the ratio of the C4 and C5 isomer pair in Table 1. If the ratio does not exceed the lower limit or the upper limit, it is abnormal, indicating that the chromatographic peak recognition is wrong or there is a co-distillation phenomenon, which serves as an index for judging the separation effect and data reliability. The ratio of neoC5 / nC5 (0.01-0.015) as a high-precision "probe", a small deviation indicates that the system may have a system error or a small amount of compound recognition error.

[0035] Carbon number distribution rule check (Cn / Cn-1) includes: calculating the concentration ratio of adjacent normal alkanes (for example, nC5 / nC4, nC6 / nC5), and judging whether the sample is contaminated by light oil or condensate oil.

[0036] Step S3-4, combined with the above three levels of check results, the evaluation result of integrity check is veto item, if not detected through the conclusion that the mole fraction calculation result does not meet the requirements, individual component compliance check of 8 items, if more than 6 items of slight deviation or more than 4 items of serious deviation, give warning, S3-3 of 8 items, if more than 6 items of slight deviation or more than 4 items of serious deviation, give warning, when S3-2 and S3-3 give warning, then the comprehensive quality evaluation result is warning, if S3-2 and S3-3 check only one gives warning or all pass, then give the evaluation result through the conclusion.

[0037] When the gas chromatograph analyzes the natural gas sample, the mole fraction should meet the general requirements of the composition range of the natural gas sample. Here, the multi-level intelligent checking system is used to check and judge the first mole fraction of each component calculated in step S2, so as to ensure the accuracy of the calculation of the mole fraction.

[0038] Step S4, after the comprehensive quality evaluation result is passed, the composition uncertainty of the first mole fraction is calculated.

[0039] In this embodiment, for the second type of analysis mode used by the online gas chromatograph, when the original mole fraction is normalized and the linear error is not corrected, the uncertainty of the original mole fraction is calculated by formula (4): (4) Wherein, is the uncertainty of the original mole fraction of the i component, is the coefficient of the first term of the response function of the i component, is the uncertainty of , is the peak area of the i component, is the uncertainty of the peak area of the i component.

[0040] In the case of correcting the linear error of the original mole fraction, the uncertainty of the original mole fraction is calculated by formula (5): (5) Wherein, is the linear error correction value of the original mole fraction of the i component, is the linear error correction value of the normalized mole fraction of the i component, is the uncertainty of the quantity in the bracket, is the average value of the quantity under the horizontal bar.

[0041] The uncertainty of the normalized mole fraction is calculated by formula (6): (6) Wherein: ​for other components in the natural gas, such as water, unknown trace components and other components, for the sensitivity (correlation) coefficient between the two quantities a and b, for the average of multiple measurements and calculation results of the normalized molar fraction of the i component.

[0042] Generally, may be considered as 0, so the above formula (6) can be simplified as formula (7): (7) Further, after obtaining the uncertainty of the normalized molar fraction, the relative expanded uncertainty thereof is calculated: (8) wherein, for the relative expanded uncertainty of the quantity in the parentheses, k = 2.

[0043] Example Two In one or more embodiments, a natural gas composition content calculation and corresponding uncertainty evaluation system is disclosed, specifically comprising: A data acquisition module for acquiring a natural gas sample to be detected; A molar fraction calculation module for calculating the original molar fraction of the sample by using the successive normalization method, and performing non-linear error correction on the original molar fraction to obtain a first molar fraction; A quality inspection module for sequentially performing data integrity verification, individual component conformity verification, and isomer and carbon number distribution verification on the original molar fraction to obtain a comprehensive quality evaluation result; An uncertainty calculation module for calculating the composition uncertainty of the first molar fraction after the comprehensive quality evaluation result passes.

[0044] Example Three The present embodiment provides an electronic device comprising a memory and a processor, and computer instructions stored on the memory and running on the processor, when the computer instructions are run by the processor, the steps of the above natural gas composition content calculation and corresponding uncertainty evaluation method are completed.

[0045] Example Four The present embodiment provides a computer readable storage medium for storing computer instructions, when the computer instructions are executed by the processor, the steps of the above natural gas composition content calculation and corresponding uncertainty evaluation method are completed.

[0046] Example Five The embodiment provides a computer program product, which comprises executable instructions, the executable instructions are computer instructions; the executable instructions are stored in a computer readable storage medium. When a processor of an electronic device reads the executable instructions from the computer readable storage medium, the processor executes the executable instructions, so that the electronic device executes the method provided in the embodiment.

[0047] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system) and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate a device for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs functions specified in one or more blocks or flows.

[0048] These computer program instructions can also be stored in a computer readable memory capable of guiding a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer readable memory produce a product including instruction apparatus, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs functions specified in one or more blocks or flows.

[0049] These computer program instructions can also be loaded into a computer or other programmable data processing device to perform a series of operation steps on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide a process for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs functions specified in one or more blocks or flows.

[0050] The description of each embodiment in the above embodiments is focused on each embodiment, and the part not described in detail in an embodiment can refer to the related description of other embodiments.

[0051] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. 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 method for calculating the composition and content of natural gas and evaluating the corresponding uncertainty, characterized in that, Comprising: Obtain a natural gas sample to be detected; Calculate the original molar fraction of the sample using the successive normalization method, and perform non-linear error correction on the original molar fraction to obtain the first molar fraction; Successively perform data integrity verification, individual component compliance verification, and isomer and carbon number distribution inspection on the original molar fraction to obtain a comprehensive quality assessment result; Calculate the compositional uncertainty for the first molar fraction after the comprehensive quality assessment result passes.

2. The method for calculating the composition and content of natural gas and evaluating the corresponding uncertainty as described in claim 1, characterized in that, The specific data integrity verification is: perform a summation verification on the first molar fraction of each component, calculate the total molar fraction of all components, and if the result falls within a preset threshold range, it is qualified.

3. The method for calculating the composition and content of natural gas and evaluating the corresponding uncertainty as described in claim 1, characterized in that, The specific individual component compliance verification is: perform a threshold boundary analysis on each key component, and compare one by one whether the measured value of each component falls within its corresponding healthy range; any value outside the range will be automatically marked, and different risk levels will be assigned according to its deviation degree.

4. The method for calculating the composition and content of natural gas and evaluating the corresponding uncertainty as described in claim 1, characterized in that, The isomer and carbon number distribution verification: Isomer ratio verification: Calculate the ratio of key isomer pairs. If the ratio is abnormal, it indicates chromatographic peak identification error or co-distillation phenomenon; Carbon number distribution law verification: Calculate the concentration ratio of adjacent normal alkanes to judge whether the sample is contaminated by light oil or condensate oil.

5. The method for calculating the composition and content of natural gas and evaluating the corresponding uncertainty as described in claim 1, characterized in that, Calculate the compositional uncertainty for the first molar fraction, and the expression is: in, The content of other components in natural gas. Let be the sensitivity coefficient between two quantities, a and b. The normalized mole fraction of component i. The original mole fraction of component i. For uncertainty, This is the average of multiple measurements and calculations of the normalized mole fraction of component i.

6. The method for calculating the composition and content of natural gas and evaluating the corresponding uncertainty as described in claim 5, characterized in that, Based on the uncertainty of the normalized molar fraction, calculate its relative expanded uncertainty: in, The relative expanded uncertainty of the quantity in parentheses.

7. A system for calculating the composition and content of natural gas and evaluating the corresponding uncertainty, characterized in that, Comprising: A data acquisition module for obtaining a natural gas sample to be detected; A molar fraction calculation module for calculating the original molar fraction of the sample using the successive normalization method, and performing non-linear error correction on the original molar fraction to obtain the first molar fraction; A quality inspection module for successively performing data integrity verification, individual component compliance verification, and logical association analysis of isomers and carbon number distribution on the original molar fraction to obtain a comprehensive quality assessment result; An uncertainty calculation module for calculating the compositional uncertainty for the first molar fraction after the comprehensive quality assessment result passes.

8. An electronic device, characterized in that, Comprising a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method for calculating the natural gas composition content and the corresponding uncertainty evaluation according to any one of claims 1-6 is completed.

9. A computer-readable storage medium, characterized in that, For storing computer instructions, when the computer instructions are executed by the processor, the method for calculating the natural gas composition content and the corresponding uncertainty evaluation according to any one of claims 1-6 is completed.

10. A computer program product, characterized in that, The computer program product includes executable instructions, and the executable instructions are stored in a computer-readable storage medium; When the processor of the electronic device reads the executable instructions from the computer-readable storage medium and executes the executable instructions, the method for calculating the natural gas composition content and the corresponding uncertainty evaluation according to any one of claims 1-6 is implemented.

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