Preparation method and application of gas standard substance for natural gas analysis

Abstract

In order to solve the technical problem that the content of each component in the target gas is lower than the required demand due to the excessive bottom gas and the large target gas pressure in the traditional preparation method of the gas standard substance, the embodiment of the present application provides a preparation method and application of the gas standard substance for natural gas analysis, comprising: S10. preparing at least one mixed component intermediate gas and at least one single component intermediate gas according to all required components in the gas standard substance; S20. mixing the mixed component intermediate gas and the single component intermediate gas to prepare the gas standard substance for natural gas analysis according to the preparation accuracy of each required component in the gas standard substance. The embodiment of the present application reduces the number of intermediate gases by using the mixed component intermediate gas containing multiple components and the single component intermediate gas, so that the introduction of the bottom gas can be reduced under the condition of meeting the weighing accuracy, and the configuration requirement of the gas standard substance for natural gas analysis is met under the condition of meeting the weighing accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method and application of a gas standard substance for natural gas analysis. BACKGROUND

[0002] In order to accurately analyze natural gas, a gas standard substance for natural gas analysis containing the same components is required. Generally, the gas standard substance for natural gas analysis contains more than ten components such as nitrogen, carbon dioxide and various saturated hydrocarbons according to the composition characteristics of natural gas.

[0003] Since the gas standard substance for natural gas analysis contains many components, it is difficult to prepare the gas standard substance by using conventional standard gas preparation methods. For example, the gas standard substance can be prepared by preparing intermediate gases of each component respectively, then filling and weighing each intermediate gas, and mixing the intermediate gases to obtain the required gas standard substance. However, if the gas standard substance is prepared by using this method, at least the following problems exist. First, since the gas standard substance for natural gas analysis contains many components, and the weighing accuracy of individual components is lower than the actual weighing accuracy in actual operation, it is difficult to accurately weigh the components with low content, so that the content of the target gas components prepared finally is different from the required content.

[0004] Although the components can be weighed according to the actual weighing accuracy, and then diluted by using methane as a base gas, so that the actual weighing accuracy can be met during preparation, since many components are required, the amount of the base gas introduced is also increased, which finally leads to too much methane in the target gas, and the pressure of the target gas is too high, so that the content of each component in the target gas is lower than the required content. SUMMARY

[0005] In order to solve the technical problem that the content of each component in the target gas is lower than the required content due to too much base gas introduced in the conventional gas standard substance preparation method, the present application provides a preparation method and application of a gas standard substance for natural gas analysis.

[0006] The present application achieves the above technical problem by the following technical scheme.

[0007] In a first aspect, the present application provides a preparation method of a gas standard substance for natural gas analysis, comprising the following steps.

[0008] S10. At least one mixed component intermediate gas and at least one single component intermediate gas are prepared according to all the required components in the gas standard substance; comprising the following steps.

[0009] a. Take multiple components from the required components of the gaseous standard substance, and mix them according to the concentration ratio of each component in the gaseous standard substance to prepare a mixed intermediate gas.

[0010] Wherein, the total pressure of the intermediate gas of the mixed components is less than the condensation pressure of each component in the intermediate gas of the mixed components;

[0011] b. Take a single component from the required components and mix it with methane according to the concentration ratio of the single component and methane in the gaseous standard substance to prepare a single-component intermediate gas;

[0012] S20. According to the required preparation precision of each component in the gas standard material, a gas standard material for natural gas analysis is prepared by mixing mixed component intermediate gas and single component intermediate gas.

[0013] Furthermore, the single component satisfies the following condition: the total pressure of the gas after mixing the single component with any one or more other components in the desired components according to the concentration ratio of the single component with any one or more other components in the desired components in the gaseous standard material is greater than the condensation pressure of any one component in the mixed gas.

[0014] Furthermore, all mixed-component intermediate gases and all single-component intermediate gases contain all the required components of the gaseous standard substance, and none of the mixed-component intermediate gases and all single-component intermediate gases contain any common components.

[0015] Furthermore, step a includes: mixing and bottling multiple components of the required components in proportion to their respective concentrations under the required conditions, ensuring that the pressure in the bottle is less than the condensation pressure of each component, and obtaining several bottles of mixed component intermediate gas.

[0016] Step b includes: bottling and weighing the individual components of the required components to obtain a single-component intermediate gas.

[0017] Furthermore, the actual sample weight of each component in the mixed intermediate gas is the theoretical sample weight of each component under the required concentration conditions, magnified by the actual sample weight accuracy; the actual sample weight of each component in the single-component intermediate gas is the theoretical sample weight of each component in the single-component intermediate gas under the required concentration conditions, magnified by the actual sample weight accuracy.

[0018] Furthermore, step S2 includes: bottling and weighing each of the mixed component intermediate gases and each of the single component intermediate gases according to the ratio of the theoretical sample amount to the actual sample amount under the required concentration conditions for each component, and mixing them to obtain a gaseous standard substance for natural gas analysis.

[0019] Furthermore, step a also includes: adding methane to each mixed component intermediate gas during bottling and weighing to obtain a mixed component intermediate gas containing methane;

[0020] Wherein, the total amount of methane in all the methane-containing intermediate gas mixtures meets the condition that: after each of the methane-containing intermediate gas mixtures and each of the single-component intermediate gases is bottled and weighed according to step S2, the sum of the methane sample weights does not exceed the theoretical sample weight of methane in the gas standard material for natural gas analysis under the required concentration conditions.

[0021] Furthermore, the total amount of methane in all the single-component intermediate gases satisfies the following condition: after each single-component intermediate gas is bottled and weighed according to step S2, the sum of the methane sample amounts does not exceed the theoretical sample amount of methane in the gas standard material for natural gas analysis under the required concentration conditions.

[0022] Furthermore, the required weighing accuracy for each of the single-component intermediate gases is within the range of actual weighing accuracy; the required weighing accuracy for each of the mixed-component intermediate gases is within the range of actual weighing accuracy.

[0023] Secondly, embodiments of the present invention provide an application of the preparation method in natural gas analysis.

[0024] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects:

[0025] This invention discloses a method and application for preparing a gaseous standard for natural gas analysis. By using mixed intermediate gas containing multiple components and single-component intermediate gas, the amount of intermediate gas is reduced. This reduces the introduction of base gas while meeting weighing accuracy requirements, thus satisfying the preparation requirements of the gaseous standard for natural gas analysis and achieving the desired maximum concentration. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the preparation method for gaseous standard substances used in natural gas analysis. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0029] Example

[0030] To address the technical problem in traditional gas standard material preparation methods where excessive pre-existing gas leads to higher target gas pressure and consequently lower-than-expected component concentrations in the target gas, the present invention provides, in a first aspect, a method for preparing gas standard materials for natural gas analysis, referring to... Figure 1 As shown, it includes:

[0031] S10. Prepare at least one mixed-component intermediate gas and at least one single-component intermediate gas according to all the desired components of the gaseous standard material; including:

[0032] a. Take multiple components from the required components of the gaseous standard substance, and mix them according to the concentration ratio of each component in the gaseous standard substance to prepare a mixed intermediate gas.

[0033] Wherein, the total pressure of the intermediate gas of the mixed components is less than the condensation pressure of each component in the intermediate gas of the mixed components;

[0034] b. Take a single component from the required components and mix it with methane according to the concentration ratio of the single component and methane in the gaseous standard substance to prepare a single-component intermediate gas;

[0035] S20. According to the required preparation precision of each component in the gas standard material, a gas standard material for natural gas analysis is prepared by mixing mixed component intermediate gas and single component intermediate gas.

[0036] Therefore, by using mixed intermediate gas containing multiple components and single-component intermediate gas, the amount of intermediate gas is reduced, which can reduce the introduction of bottom gas while meeting the weighing accuracy requirements, and meet the configuration requirements of gas standard materials for natural gas analysis.

[0037] Furthermore, the single component satisfies the following condition: the total pressure of the gas after mixing the single component with any one or more other components in the desired components according to the concentration ratio of the single component with any one or more other components in the desired components in the gaseous standard material is greater than the condensation pressure of any one component in the mixed gas.

[0038] Furthermore, all mixed-component intermediate gases and all single-component intermediate gases contain all the required components of the gaseous standard substance, and none of the mixed-component intermediate gases and all single-component intermediate gases contain any common components.

[0039] Furthermore, step a includes: mixing and bottling multiple components of the required components in proportion to their respective concentrations under the required conditions, ensuring that the pressure in the bottle is less than the condensation pressure of each component, and obtaining several bottles of mixed component intermediate gas.

[0040] Step b includes: bottling and weighing the individual components of the required components to obtain a single-component intermediate gas.

[0041] Optionally, the method for preparing gaseous standard substances for natural gas analysis includes the following steps:

[0042] S1. Determine the concentration conditions required for the composition of gaseous standard substances for natural gas analysis and the required components other than methane, determine the condensation pressure of each component, and calculate the theoretical sample weight of each component under each required concentration condition.

[0043] S2. Weigh multiple components in the required composition according to their respective proportions under the required concentration conditions, and ensure that the pressure in the bottle is less than the condensation pressure of each component, to obtain a mixed intermediate gas in which the components in several bottles do not overlap. The actual sample weight of each component in the mixed intermediate gas is an amplified value of the theoretical sample weight of each component under the required concentration conditions based on the actual sample weight accuracy.

[0044] S3. The remaining components in the required components are bottled and weighed separately, and then diluted with methane to obtain several single-component intermediate gases. The actual sample weight of the components contained in the single-component intermediate gas is the theoretical sample weight of the contained components under the required concentration conditions, based on the amplified value of the actual sample weight accuracy.

[0045] S4. The intermediate gases of each mixed component and each single component are bottled and weighed according to the ratio of the theoretical sample amount to the actual sample amount of each component under the required concentration conditions. After mixing, a gas standard substance for natural gas analysis under the required concentration conditions is obtained.

[0046] In an optional embodiment, in step S2, the components contained in the intermediate gas of the mixed components are multiple components that maintain the same proportion under multiple required concentration conditions.

[0047] According to JJF 1344-2012 "General Technical Requirements for the Development (Production) of Gas Standard Reference Materials", when developing gas standard reference materials, at least one concentration point needs to be determined in addition to the high and low concentration limits to form gas standard reference materials with three concentration conditions, thereby completing the coverage of the entire concentration range specified in the regulations. In the existing technology, it is necessary to prepare an intermediate gas for each required concentration condition.

[0048] Under the three concentration settings mentioned above, some components have the same proportion under multiple concentration conditions. Taking this situation into consideration, this invention configures these components with unchanged proportions into one or several bottles of mixed component intermediate gas. This allows the same bottle of mixed component intermediate gas to be used as the raw material for gaseous standard substances for natural gas analysis under multiple concentration conditions. This invention can greatly improve the configuration efficiency of gaseous standard substances for natural gas analysis and the utilization rate of mixed component intermediate gas.

[0049] Furthermore, the actual sample weight of each component in the mixed intermediate gas is the theoretical sample weight of each component under the required concentration conditions, magnified by the actual sample weight accuracy; the actual sample weight of each component in the single-component intermediate gas is the theoretical sample weight of each component in the single-component intermediate gas under the required concentration conditions, magnified by the actual sample weight accuracy.

[0050] Furthermore, step S20 includes: weighing each of the mixed component intermediate gases and each of the single component intermediate gases according to the ratio of the theoretical sample amount to the actual sample amount under the required concentration conditions for each component, and mixing them to obtain a gaseous standard substance for natural gas analysis.

[0051] Furthermore, the required weighing accuracy for each of the single-component intermediate gases is within the range of actual weighing accuracy; the required weighing accuracy for each of the mixed-component intermediate gases is within the range of actual weighing accuracy.

[0052] Furthermore, step a also includes: adding methane to each mixed component intermediate gas during bottling and weighing to obtain a mixed component intermediate gas containing methane;

[0053] Wherein, the total amount of methane in all the methane-containing intermediate gas mixtures meets the condition that: after each of the methane-containing intermediate gas mixtures and each of the single-component intermediate gases is bottled and weighed according to step S20, the sum of the methane sample weights does not exceed the theoretical sample weight of methane in the gas standard material for natural gas analysis under the required concentration conditions.

[0054] Optionally, the sum of the methane sample weights is equal to the theoretical sample weight of methane in the gaseous standard for natural gas analysis under the required concentration conditions.

[0055] The embodiments of the present invention, by rationally designing the total sample quantity of each mixed component intermediate gas and each single component intermediate gas, ensure that the weighing accuracy of each mixed component intermediate gas and intermediate gas required for preparing gaseous standard materials for natural gas analysis is within the actual weighing accuracy range when using mixed component intermediate gas and single component intermediate gas to prepare gaseous standard materials for natural gas analysis.

[0056] Furthermore, the total amount of methane in all the single-component intermediate gases satisfies the following condition: after each single-component intermediate gas is bottled and weighed according to step S20, the sum of the methane sample amounts does not exceed the theoretical sample amount of methane in the gas standard material for natural gas analysis under the required concentration conditions.

[0057] When preparing single-component intermediate gases, in order to ensure that the required amount of each component in the single-component intermediate gas is within the actual weighing accuracy range, the component is first scaled up according to its theoretical weighing amount at the required concentration to obtain the actual weighing amount of the component. Then, it is diluted with methane to ensure that the weighing accuracy required for the single-component intermediate gas is within the actual weighing accuracy range when preparing the gas standard for natural gas analysis. On the other hand, when preparing mixed-component intermediate gases, in order to meet the actual weighing accuracy, the mixed-component intermediate gas can also be diluted with methane. Since methane is introduced in the process, after weighing each mixed-component intermediate gas and each single-component intermediate gas in step S20, the sum of the methane weighing amounts does not exceed the theoretical weighing amount of methane required for the gas standard for natural gas analysis under the required concentration conditions. Preferably, the final sum of the methane weighing amounts is exactly equal to the theoretical weighing amount of methane at the required concentration to avoid the need to supplement methane if it is insufficient.

[0058] In an alternative embodiment, the condensation pressure is calculated using a phase diagram or partial pressure.

[0059] In an optional embodiment, step S1 and / or step S2, after bottling and weighing, further includes the step of homogenizing the components in the bottle.

[0060] Secondly, embodiments of the present invention provide an application of the preparation method in natural gas analysis.

[0061] Experimental Example

[0062] The principles and features of the present invention are described below with reference to examples. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0063] The following discloses various implementation methods or embodiments of the described subject matter technical solutions. To simplify the disclosure, specific embodiments of one or more arrangements of the features are described below, but the embodiments are not intended to limit this specification. The connection between the first feature and the second feature described later in the specification can include implementations with direct connection, implementations that form additional features, and further, implementations that use one or more other intervening features to indirectly connect or combine the first feature and the second feature with each other, so that the first feature and the second feature are not directly connected.

[0064] Example 1

[0065] In this embodiment, the actual weighing accuracy that can be achieved is 1g.

[0066] In this embodiment, the composition of the natural gas analysis standard material under three concentration conditions is shown in Table 1:

[0067] Table 1 (Unit: ppm)

[0068] Component Molecular weight Low concentration point Intermediate concentration point High limit concentration point [N2] 28.0134 2.5 5 10 CO2 44.01 1.5 2 4 [C2H6] 30.069 2.5 5 10 [C3H8] 44.096 0.7 2 4.5 i-C4H 10 ]] 58.122 0.35 0.5 1 n-C4H 10 ]] 58.122 0.35 0.5 1 i-C5H 12 ]] 72.149 0.1 0.15 0.3 neo-C5H 12 ]] 72.149 0.1 0.15 0.3 n-C5H 12 ]] 72.149 0.1 0.15 0.3 n-C6H 14 ]] 86.175 0.1 0.15 0.3

[0069] As can be seen from Table 1, the required concentration conditions in this embodiment include three points, which are defined as the low concentration point, the intermediate concentration point, and the high concentration limit point, respectively.

[0070] The condensation pressures of the above components were calculated using phase diagrams or partial pressures to determine the maximum pressure. The resulting preparation pressures and the theoretical sample quantities of each component under three concentration conditions are shown in Table 2.

[0071] Table 2

[0072]

[0073] As can be seen from Table 2, in this embodiment, the theoretical sample weight required for heavy hydrocarbons (C5 and above) is less than 1g. With an actual sample weight accuracy of 1g, the repeatability ratio is only 10. -2 In such a case, if the existing gas standard preparation method is used for direct weighing and preparation, the uncertainty of the gas standard will be higher than 1%. If each required component is prepared by diluting it with methane base gas, the amount of methane base gas introduced will exceed 202g, 63g and 34g respectively. The already mixed methane cannot be removed from the target container, and the pressure of the gas standard preparation will be too high, resulting in the concentration of the target component being lower than required.

[0074] Therefore, based on the above, and taking into account the condensation pressure of each component, especially the easy condensation of components with C5 and above, the present invention provides four sets of intermediate gases, the composition of which is shown in Table 3:

[0075] Table 3

[0076]

[0077]

[0078] Among them, due to n-C6H 14 and n-C5H 12 It is relatively easy to condense, so in this embodiment it is used as a single-component intermediate gas. Since the proportions of each component in the mixed intermediate gas No. 3 and No. 4 remain basically unchanged at the intermediate concentration point and the upper limit concentration point, this invention mixes these components according to their proportions at the intermediate concentration point to form a mixed-component intermediate gas.

[0079] After the intermediate gas weighing is completed, each intermediate gas will be used as the raw material gas. The required sample weight will be weighed according to the ratio of the theoretical sample weight to the actual sample weight of each component contained in the intermediate gas. Weighing will be performed again. Since the proportion at the upper limit concentration point remains basically unchanged in this embodiment, the same intermediate gas can be used to prepare gas standard materials for natural gas analysis at the intermediate concentration point and the upper limit concentration point.

[0080] Based on the formula: Required intermediate gas sample quantity = Total amount of intermediate gas × Theoretical sample quantity of each component / Actual sample quantity, the final sample quantities of each intermediate gas are determined as shown in Table 4.

[0081] Table 4

[0082]

[0083] After the calculations in the above tables, in order to ensure sufficient gas volume, this invention involves the actual filling of multiple intermediate gas cylinders during actual implementation. The specific actual sample quantities are shown in Table 5:

[0084] Table 5

[0085]

[0086]

[0087] Among them, bottle number 759610 corresponds to single-component intermediate gas 1, bottle numbers 759688 and 759744 correspond to single-component intermediate gas 2, bottle numbers 759761 and 759784 correspond to mixed-component intermediate gas 3, and bottle numbers 759387 and 759728 correspond to mixed-component intermediate gas 4.

[0088] As can be seen from the data in Table 5, since the total amount of hexane / methane in each intermediate gas is sufficient, one bottle of intermediate gas is enough to meet the requirements, but the filling amount of the remaining components may be insufficient. To ensure sufficient usage of each group of intermediate gas in subsequent configurations, two bottles of intermediate mixed component intermediate gas 3, mixed component intermediate gas 4, and single component intermediate gas 2 were configured in this embodiment.

[0089] After weighing the intermediate gases according to Table 5, the gases were heated evenly. The intermediate gases not recorded in the table were used as raw materials for weighing the target gases. The specific sample quantities are shown in Table 6.

[0090] Table 6 (Unit: g)

[0091]

[0092] The final concentrations of the components in each target gas cylinder after weighing are shown in Table 7.

[0093] Table 7 (Unit: %)

[0094] Vial number 759384 759602 759283 759289 759372 739370 [N2] 2.5019 4.3158 5.4004 9.2619 9.4182 2.6187 CO2 1.3526 1.9254 1.9024 4.4563 3.6521 1.3034 [C2H6] 2.5255 4.3567 5.4515 9.3495 9.5073 2.5074 [C3H8] 1.5152 2.1568 2.1310 5.0574 4.1447 1.4793 i-C4H 10 ]] 0.3343 0.4759 0.4702 1.1158 0.9144 0.3263 n-C4H 10 ]]> 0.3393 0.4830 0.4772 1.1329 0.9284 0.3314 i-C5H 12 ]]> 0.1051 0.1496 0.1478 0.3507 0.2874 0.1026 neo-C5H 12 ]]> 0.0765 0.1319 0.1650 0.2830 0.2878 0.0755 n-C5H 12 ]]> 0.0972 0.1317 0.1637 0.3048 0.2991 0.0972 n-C6H 14 ]]> 0.0974 0.1513 0.1466 0.2503 0.3166 0.1120 CH4 91.0552 85.7221 83.5441 68.4374 70.2440 91.0464

[0095] Among them, the concentrations of each component in bottle numbers 759283 and 759289 are close to the theoretical concentrations required for the gas standard material for natural gas analysis at the intermediate and upper concentration points.

[0096] As can be seen from the embodiments of the present invention, the present invention can utilize mixed intermediate gas containing multiple components to prepare gas standard materials for natural gas analysis. This ensures that during the preparation of gas standard materials for natural gas analysis, the amount of base gas will not exceed the required amount due to excessive quantity of single-component intermediate gas, thus preventing the preparation of gas standard materials for natural gas analysis at the required concentration conditions. At the same time, it can also ensure the accuracy of the final sample weighing of each component.

[0097] This invention utilizes the characteristic that natural gas analysis gas standard substances have some components with the same proportion under different concentration conditions. By rationally configuring the components in the mixed intermediate gas, the directionality of the intermediate gas for natural gas analysis gas standard substances is improved. By using the same bottle of mixed intermediate gas with multiple components, natural gas analysis gas standard substances can be prepared under various concentration conditions, which can effectively improve the utilization efficiency of intermediate gas and enhance production efficiency.

[0098] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a gaseous standard substance for natural gas analysis, characterized in that, include: S10. Prepare at least one mixed-component intermediate gas and at least one single-component intermediate gas according to all the desired components of the gaseous standard material; including: a. Take multiple components from the required components of the gaseous standard substance, and mix them according to the concentration ratio of each component in the gaseous standard substance to prepare a mixed intermediate gas. Wherein, the total pressure of the intermediate gas of the mixed components is less than the condensation pressure of each component in the intermediate gas of the mixed components; b. Take a single component from the required components and mix it with methane according to the concentration ratio of the single component and methane in the gaseous standard substance to prepare a single-component intermediate gas; S20. According to the required preparation precision of each component in the gas standard material, a gas standard material for natural gas analysis is prepared by mixing mixed component intermediate gas and single component intermediate gas. The single component satisfies the following condition: the total pressure of the gas after mixing the single component with any one or more other components in the required components according to the concentration ratio of the single component with any one or more other components in the required components in the gaseous standard material is greater than the condensation pressure of any one component in the mixed gas. The intermediate gas in the mixed components contains multiple components that maintain the same proportions under the required concentration conditions.

2. The method for preparing gaseous standard substances for natural gas analysis as described in claim 1, characterized in that, All mixed-component intermediate gases and all single-component intermediate gases contain all the required components of the gaseous standard substance, and none of the mixed-component intermediate gases and all single-component intermediate gases contain any common components.

3. The method for preparing gaseous standard substances for natural gas analysis as described in claim 2, characterized in that, Step a includes: mixing and bottling multiple components of the required components in proportion to their respective concentrations under the required conditions, ensuring that the pressure in the bottle is less than the condensation pressure of each component, and obtaining several bottles of mixed component intermediate gas. Step b includes: bottling and weighing the individual components of the required components to obtain a single-component intermediate gas.

4. The method for preparing gaseous standard substances for natural gas analysis as described in claim 3, characterized in that, The actual sample weight of each component in the intermediate gas of the mixed components is the theoretical sample weight of each component under the required concentration conditions, which is an amplified value based on the actual sample weight accuracy. The actual sample weight of each component in the single-component intermediate gas is the theoretical sample weight of each component in the single-component intermediate gas under the required concentration conditions, which is an amplified value based on the actual sample weight accuracy.

5. The method for preparing gaseous standard substances for natural gas analysis as described in claim 3, characterized in that, Step S20 includes: weighing each of the mixed component intermediate gases and each of the single component intermediate gases according to the ratio of the theoretical sample amount to the actual sample amount of each component under the required concentration conditions, and mixing them to obtain a gaseous standard substance for natural gas analysis.

6. The method for preparing gaseous standard substances for natural gas analysis as described in claim 5, characterized in that, Step a further includes: during bottling and weighing, adding methane to each intermediate gas of the mixed components to obtain an intermediate gas of the mixed components containing methane; Wherein, the total amount of methane in all the methane-containing intermediate gas mixtures meets the condition that: after each of the methane-containing intermediate gas mixtures and each of the single-component intermediate gases is bottled and weighed according to step S20, the sum of the methane sample weights does not exceed the theoretical sample weight of methane in the gas standard material for natural gas analysis under the required concentration conditions.

7. The method for preparing gaseous standard substances for natural gas analysis as described in claim 5, characterized in that, The total amount of methane in all the single-component intermediate gases satisfies the following condition: after each single-component intermediate gas is bottled and weighed according to step S20, the sum of the methane sample amounts does not exceed the theoretical sample amount of methane in the gas standard material for natural gas analysis under the required concentration conditions.

8. The method for preparing gaseous standard substances for natural gas analysis as described in claim 5, characterized in that, The required weighing accuracy for each of the single-component intermediate gases is within the range of actual weighing accuracy. The required weighing accuracy for the intermediate gas of each of the mixed components is within the range of actual weighing accuracy.

9. The application of the preparation method according to any one of claims 1-8 in natural gas analysis.

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