CN113804769B - Light hydrocarbon carbon isotope enrichment analytical equipment in natural gas - Google Patents
Light hydrocarbon carbon isotope enrichment analytical equipment in natural gas Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 239000004215 Carbon black (E152) Substances 0.000 title claims abstract description 63
- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 63
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 63
- 239000003345 natural gas Substances 0.000 title claims abstract description 34
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 27
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 27
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims abstract description 64
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000004458 analytical method Methods 0.000 claims abstract description 19
- 238000012360 testing method Methods 0.000 claims abstract description 17
- 238000002360 preparation method Methods 0.000 claims abstract description 16
- 238000001514 detection method Methods 0.000 claims abstract description 13
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 13
- 239000007789 gas Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 12
- 238000013375 chromatographic separation Methods 0.000 claims description 10
- 239000001307 helium Substances 0.000 claims description 10
- 229910052734 helium Inorganic materials 0.000 claims description 10
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 10
- 239000000178 monomer Substances 0.000 claims description 8
- 238000010201 enrichment analysis Methods 0.000 claims description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 5
- 235000011089 carbon dioxide Nutrition 0.000 claims description 5
- 239000012159 carrier gas Substances 0.000 claims description 4
- 150000002429 hydrazines Chemical class 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000002474 experimental method Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 230000000155 isotopic effect Effects 0.000 claims 1
- 238000012856 packing Methods 0.000 claims 1
- 238000005194 fractionation Methods 0.000 abstract description 3
- 238000005070 sampling Methods 0.000 abstract description 2
- 238000002347 injection Methods 0.000 abstract 1
- 239000007924 injection Substances 0.000 abstract 1
- 238000000926 separation method Methods 0.000 description 12
- 238000004587 chromatography analysis Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 238000009833 condensation Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
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- 239000000126 substance Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
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- 230000008020 evaporation Effects 0.000 description 2
- 230000008014 freezing Effects 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000019577 caloric intake Nutrition 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
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- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/08—Preparation using an enricher
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/14—Preparation by elimination of some components
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/62—Detectors specially adapted therefor
- G01N30/72—Mass spectrometers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
- G01N2030/8809—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample
- G01N2030/884—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample organic compounds
- G01N2030/8854—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample organic compounds involving hydrocarbons
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
- G01N2030/8809—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample
- G01N2030/8868—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample elemental analysis, e.g. isotope dilution analysis
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Abstract
The utility model provides a light hydrocarbon carbon isotope enrichment analytical equipment in natural gas, includes preparation chromatograph, preparation chromatograph connects nitrogen source and main line, and vacuum system, bubble system and test system are connected respectively on main line, vacuum system includes vacuum gauge and vacuum pump, bubble system includes the bubble gauge, test system includes cold hydrazine one, cold hydrazine two, cold hydrazine three and isotope analysis test system who connects gradually. The invention carries out on-line isotope detection on the enriched and separated light hydrocarbon, prevents fractionation of carbon isotopes in multi-sampling and sample injection, and ensures the accuracy of analysis and test.
Description
Technical Field
The invention relates to an isotope enrichment analysis device, in particular to an enrichment analysis device for light hydrocarbon carbon isotopes in natural gas.
Background
The carbon isotopes with different components of the natural gas can accurately judge the cause type of the natural gas and evaluate the maturity of the natural gas, and the prior application is mainly focused on C 1 ～C 5 Component carbon isotope studies, however C 1 ～C 5 The molecular species of the components are limited and the structure is simple, the information provided by the carbon isotope is relatively limited, and the component contains C in the moisture 1 ～C 5 Outside the components, C 6 ～C 8 The light hydrocarbon of the components has high visibility, the molecular structure is complex, and the research on the characteristics of the carbon isotopes of the series of monomers is of great significance to the exploration and research on the cause of natural gas, the identification of the type of gas and the comparison of gas sources.
Because the content of light hydrocarbon in natural gas is usually smaller, the C in the natural gas is accurately analyzed 6 ～C 8 The difficulty of the light hydrocarbon isotope of the component is high, and people adopt an online analysis technology of the carbon isotope, however, because the sample amount entering the detector in actual analysis is small, data fluctuation is often generated, and when the light hydrocarbon content is extremely low, the detection line is often lower than the detection line and cannot be detected, so that the development of a novel device and a novel method for enriching the light hydrocarbon component in natural gas are widely focused.
In conventional chromatographic separation methods, separation of various gas components in natural gas can be achieved by adjusting chromatographic conditions, however, wherein C 5 Gas-like component and C 6 The time interval of the retention time of the gas-like component is limited, so that the enrichment of C is easy to cause in the enrichment process 6 ～C 8 The component contains a certain amount of C 5 Component due to part C 5 Freezing points of the components and part C 6 Of componentsThe freezing points are similar, so that C cannot be realized in the subsequent cold trap 5 Component and C 6 Complete separation of the components. The effect of the analysis of the components of the light hydrocarbon is relatively small when the analysis of the carbon isotopes of the light hydrocarbon components is performed, however, the effect of the analysis of the carbon isotopes of the subsequent light hydrocarbon is caused by the fact that the retention time of the adjacent light hydrocarbon components is relatively small and cannot be completely separated.
In the enrichment of isotopes, various cold hydrazines are often used. A cold trap is a device that prevents vapor or liquid from entering the measuring instrument from the system, or from the measuring instrument into the system. It provides a very low temperature surface on which molecules can agglomerate and can increase the vacuum level by one to two orders of magnitude. However, improper use of cold traps can reduce the accuracy of the instrument, resulting in damage to the instrument or system, creating a physical accident. For example, many lipid mixtures used in cold traps are toxic and can also cause explosion accidents when handled improperly. The rate at which the cold trap evaporates is affected not only by the energy intake, but also by the pump speed of the vacuum pump. The larger sample evaporation surface area is the bottleneck affecting the efficiency of the vacuum pump, not the sample volume and quantity. It is more efficient to use a cold trap rather than a larger vacuum pump. Due to the use of the cold trap, on one hand, the condensation of water vapor is facilitated, and on the other hand, the evaporation density of the organic solvent is improved, and the condensation is easier.
Cold trap processing is a cooling device that collects substances within a certain melting point range. A U-shaped pipe is placed in the refrigerant, when gas passes through the U-shaped pipe, substances with high melting points are changed into liquid, and substances with low melting points pass through the U-shaped pipe to play a role of separation. However, the use of cold hydrazine alone often fails to achieve satisfactory results due to the complex components in natural gas. The data of various experiments are often inaccurate and the experimental efficiency is low
In view of the above, a reasonable and effective system for preparing the light hydrocarbon component carbon isotope in the natural gas is designed, and a novel sample preparation method is introduced.
Disclosure of Invention
The invention aims to solve the problem of inaccurate analysis of the carbon isotopes of the light hydrocarbon component in the natural gas, and provides a system and a method for enriching the light hydrocarbon component in the natural gas.
In order to achieve the aim, the invention provides an enrichment analysis test system and method for light hydrocarbon components in natural gas, which adopts preparation chromatography, and can effectively realize C in the light hydrocarbon by adjusting the chromatographic conditions of the preparation chromatography 1 ～C 5 Component and C 6 ～C 8 Complete separation of the components. The invention adopts the chromatographic separation and multi-cold trap enrichment coupling separation mode, and is different from the conventional chromatographic separation for completely separating different components, the chromatographic separation conditions set by the invention aim at realizing C 5 Component and C 6 The time interval of the retention time of the components is expanded as much as possible to achieve complete separation thereof.
When all C 6 ～C 8 When the components are completely enriched, multiple cold traps are adopted to separate, so as to realize the light hydrocarbon components (C 6 And C 7 + Component separation), the separation effect of light hydrocarbon components with different carbon numbers can be effectively ensured;
and the chromatographic conditions are optimized, and the accurate test of carbon isotopes of different light hydrocarbon components is finally realized.
The specific implementation method comprises the following steps:
the utility model provides a light hydrocarbon carbon isotope enrichment analytical equipment in natural gas, includes preparation chromatograph, preparation chromatograph connects nitrogen source and main line, and vacuum system, bubble system and test system are connected respectively on main line, vacuum system includes vacuum gauge and vacuum pump, bubble system includes the bubble gauge, test system includes cold hydrazine one, cold hydrazine two, cold hydrazine three and isotope analysis test system who connects gradually.
Valves are preferably provided between the nitrogen source and the preparation chromatograph, between the main line and the preparation chromatograph, between the vacuum system and the main line, between the bubble meter and the main line, between the first cold hydrazine and the second cold hydrazine, between the second cold hydrazine and the third cold hydrazine, between the third cold hydrazine and the isotope testing system, respectively.
Preferably the valve is a vacuum valve.
Preferably, the first, second and third cold hydrazines are different cold hydrazines.
Preferably, the cold hydrazine comprises at least one liquid nitrogen cold trap, one dry ice cold trap and one alcohol cold hydrazine.
The invention has the following beneficial effects:
adopts a preparative chromatographic separation method, and optimizes chromatographic conditions to ensure C in the chromatograph 5 Component and C 6 The retention time interval of the above components is more than 7min, realizing C 6 ～C 8 Component and C 1 ～C 5 Complete separation of the components;
adopting a light hydrocarbon purifying method to purify C in the light hydrocarbon 6 ～C 8 The component is completely reserved and the C is further removed 1 ～C 5 Small amounts of moisture in the components and natural gas;
adopting multi-type cold trap to further realize C 6 Component and C 7 Separating the above components;
the enrichment and separation light hydrocarbon is subjected to on-line isotope detection, so that fractionation of carbon isotopes in multi-time sampling and sample introduction is prevented, and the accuracy of analysis and test is ensured.
Drawings
FIG. 1 is a schematic diagram of a carbon isotope enrichment analysis system according to the present invention.
The reference numerals are as follows:
1. preparing a chromatograph; 2. a vacuum valve; 3. helium gas; 4. a vacuum valve; 5. a vacuum valve; 6. a vacuum gauge; 7: a vacuum pump; 8. a vacuum valve; 9. a bubble meter; 10. a vacuum valve; 11. a first cold trap; 12. a vacuum valve; 13. a cold trap II; 14. a vacuum valve; 15. a cold trap III; 16. a vacuum valve; 17. isotope analysis test system
Detailed Description
The detailed description and technical content of the present invention are described below with reference to the accompanying drawings, which are provided for reference and description only, and are not intended to limit the present invention.
According to the embodiment shown in fig. 1, the device for isotopically enriching and analyzing the light hydrocarbon component monomer hydrocarbon carbon in the natural gas comprises a light hydrocarbon enrichment system and an analysis and detection system, wherein the light hydrocarbon enrichment system comprises a chromatograph, a vacuum valve, a vacuum pump, a helium gas circuit, a cold trap, a bubble meter and a vacuum valve which are connected in sequence; the analysis and detection system mainly comprises a chromatograph and an isotope mass spectrometer.
In order to achieve the purpose, the invention adopts the following technical scheme that the detection of the carbon isotope of the light hydrocarbon component carbon isotope monomer hydrocarbon carbon isotopes in the natural gas is divided into five steps:
(1) Vacuum detection
Firstly, introducing helium into a system to remove impurity gas in the system, starting a vacuum system, and observing the vacuum degree in a sample cell through a vacuum gauge until the vacuum degree reaches 10 -2 pa。
(2) Chromatographic separation
Injecting natural gas into preparation chromatograph, optimizing chromatographic conditions by multiple experiments, wherein the natural gas can be used for preparing light hydrocarbon C through the preparation chromatograph 6 ～C 8 Component and C 1 ～C 5 The components are completely separated, the chromatographic conditions are (chromatographic column is a pack Q packed column, the temperature programming condition is that the initial temperature is 40 ℃, the temperature is kept constant for 1 minute, then the temperature is raised to 145 ℃ at 10 ℃/min for 15 minutes, then the temperature is raised to 145 ℃ at 2 ℃/min for 15 minutes, the carrier gas is helium, and the flow rate is 13 mL/min)
(3) Light hydrocarbon purification
Further purifying and enriching light hydrocarbon component obtained by preparative chromatographic separation in two cold traps, separating water and hydrocarbon gas by cold trap one, and C by cold trap two 6 ～C 8 Enrichment of the components until cold hydrazine three.
(4) Graded release
Based on the temperature difference of different cold traps (such as a first cold hydrazine liquid nitrogen cold trap, a second cold hydrazine alcohol cold trap and a third cold hydrazine dry ice cold trap), enriched gas is transferred from the liquid nitrogen cold trap to the dry ice cold trap to realize C in light hydrocarbon components 6 Component (A)And C 7 Separation of the above components.
(5) Analytical detection
C to be released 6 Component and C 7 The components are introduced into an isotope chromatography-mass spectrometry detection system, and the light hydrocarbon component monomer hydrocarbon is separated, reacted and detected by chromatography, so that the carbon isotope analysis of the light hydrocarbon monomer hydrocarbon in the natural gas is realized, and the chromatographic conditions are as follows: al (Al) 2 O 3 The capillary column is heated to the initial temperature of 40 ℃ for 1 minute at constant temperature, then heated to 145 ℃ at 1.5 ℃/min for 20 minutes at constant temperature, then heated to 280 ℃ at 2 ℃/min for 15 minutes at constant temperature, the carrier gas is helium, and the flow rate is 3mL/min
Compared with the existing enrichment and detection method of light hydrocarbon, the method adopts a two-step enrichment method of preparative chromatographic separation and cold trap condensation for the first time, thereby ensuring the light hydrocarbon C 6 ～C 8 Component and C 1 ～C 5 The components are completely separated, the fractionation of light hydrocarbon is prevented, then a plurality of types of cold traps are adopted, the slow release of light hydrocarbon gas is realized, and finally the mass spectrometer is coupled, so that the light hydrocarbon C is realized 6 ～C 8 The best separation effect of the components finally realizes the enrichment and accurate test of the light hydrocarbon component monomer hydrocarbon in the natural gas,
the enrichment and analysis test method of the system is described below through operation in practical application:
(1) The vacuum valves 2, 4, 8, 10, 12, 14 and 16 are closed to fill the reaction line with helium, and when continuous bubbles are observed in the bubble meter 9, the vacuum valves 2, 8 and 16 are opened.
(2) Opening a vacuum valve 5, and vacuumizing the reaction tube;
(3) When the vacuum degree of the sample tube reaches 10 -2 At Pa, the vacuum valves 5, 10, 12 and 14 are opened;
(4) The temperature of a cold trap is regulated, the cold trap 11 is an alcohol liquid nitrogen cold trap, and the cold trap 13 is a liquid nitrogen cold trap;
(5) Taking 5ml natural gas sample, injecting into preparative chromatograph 1, and closing vacuum valve 8 to make C in natural gas 1 ～C 5 The components are vented, when the beginning of light hydrocarbon C is observed in the chromatogram 6 When the components are separatedThe air valve 8 is closed, the vacuum valves 10 and 12 are closed, trace water gas in the natural gas is removed through the cold trap 11, and light hydrocarbon C in the natural gas is removed 6 ～C 8 The components remain in the cold trap 13;
(6) Opening the vacuum valve 12, closing the vacuum valve 14, and slowly heating the cold trap 13;
(7) Closing the vacuum valves 2, 4, 10 and 12, injecting helium gas into the pipeline;
(8) Closing the vacuum valve 16 to remove C from the light hydrocarbon 6 The components enter a chromatograph and react and are detected;
(9) The vacuum valve 14 is disconnected, and the cold trap 15 is slowly heated;
(10) Closing the vacuum valve 16 to cause C in the light hydrocarbon 7 The above components enter chromatography and isotope mass spectrometers.
The above description is only a few preferred embodiments of the present invention, and flexible modifications are possible, as well as modifications and equivalents thereof, by anyone skilled in the art using the above-described embodiments. Therefore, any simple modification or equivalent made in accordance with the embodiments of the present invention falls within the scope of the present invention as claimed.
Claims (1)
1. A method for isotopic enrichment analysis of light hydrocarbon carbon in natural gas is characterized in that:
the method comprises the steps that a light hydrocarbon carbon isotope enrichment analysis device in natural gas is used, the device comprises a preparation chromatograph, the preparation chromatograph is connected with a nitrogen source and a main pipeline, a vacuum system, a bubble system and a test system are respectively connected to the main pipeline, the vacuum system comprises a vacuum gauge and a vacuum pump, the bubble system comprises a bubble gauge, and the test system comprises a first cold hydrazine, a second cold hydrazine, a third cold hydrazine and an isotope analysis test system which are sequentially connected;
valves are respectively arranged between the nitrogen source and the preparation chromatograph, between the main pipeline and the preparation chromatograph, between the vacuum system and the main pipeline, between the bubble meter and the main pipeline, between the cold hydrazine I and the cold hydrazine II, between the cold hydrazine II and the cold hydrazine III, and between the cold hydrazine III and the isotope testing system, and are vacuum valves; the first cold hydrazine, the second cold hydrazine and the third cold hydrazine are different cold hydrazines;
the cold hydrazine at least comprises a liquid nitrogen cold trap, a dry ice cold trap and an alcohol cold hydrazine;
the analysis method comprises the following steps:
step 1, vacuum detection
Firstly introducing helium into the system to remove impurity gas in the system, starting a vacuum system, and observing the vacuum degree in the sample cell by a vacuum gauge until the vacuum degree reaches 10 -2 pa；
Step 2, chromatographic separation
Injecting natural gas into preparation chromatograph, optimizing chromatographic conditions by multiple experiments, and purifying light hydrocarbon C by natural gas through preparation chromatograph 6 ～C 8 Component and C 1 ～C 5 The components are completely separated, and the chromatographic conditions are as follows: the chromatographic column is a packing Q column, the temperature programming condition is that the initial temperature is 40 ℃, the temperature is kept for 1 minute, then the temperature is increased to 145 ℃ at 10 ℃/min, the temperature is kept for 15 minutes, then the temperature is increased to 145 ℃ at 2 ℃/min, the temperature is kept for 15 minutes, the carrier gas is helium, and the flow rate is 13 mL/min;
step 3, purifying the light hydrocarbon
Further purifying and enriching light hydrocarbon component obtained by preparative chromatographic separation in two cold traps, separating water and hydrocarbon gas by liquid nitrogen cold trap one, and C by alcohol cold trap two 6 ～C 8 Enrichment of the components until dry ice-cold hydrazine III;
step 4, release in stages
The enriched gas is transferred from the liquid nitrogen cold trap to the dry ice cold trap III to realize C in the light hydrocarbon component 6 Component and C 7 Separating the above components;
step 5, analyzing and detecting
C to be released 6 Component and C 7 The components are introduced into an analysis and detection system consisting of a chromatograph and an isotope mass spectrometer, and the light hydrocarbon component monomer hydrocarbon is separated, reacted and detected by the chromatograph, so that the carbon isotope analysis of the light hydrocarbon monomer hydrocarbon in the natural gas is realized, and the chromatographic conditions are as follows: al (Al) 2 O 3 Capillary column, temperature programming condition is initial temperatureThe temperature is kept at 40 ℃ for 1 minute, then the temperature is raised to 145 ℃ at 1.5 ℃/min, the temperature is kept for 20 minutes, the temperature is raised to 280 ℃ at 2 ℃/min, the temperature is kept for 15 minutes, the carrier gas is helium, and the flow rate is 3 mL/min.
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| DE19817529A1 (en) * | 1998-04-09 | 1999-10-14 | Inst Umwelttechnologien Gmbh | Enriching carbon isotopes using a gas chromatography impulse method |
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| CN107478488A (en) * | 2016-06-07 | 2017-12-15 | 中国石油化工股份有限公司 | Minor Heavy Hydrocarbon gas isotope sample-preparing system and its method for making sample |
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| CN204630990U (en) * | 2015-03-25 | 2015-09-09 | 中国石油天然气股份有限公司 | A kind of for trace hydro carbons enriching apparatus in the rock gas of stable isotope detection |
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