A method for collecting light hydrocarbons in natural gas in a laboratory and an online circulation system and application thereof

Abstract

The present invention provides a method for collecting light hydrocarbons in natural gas in a laboratory, an online circulation system and an application thereof, and relates to the field of gas geochemical analysis. The method comprises the following steps: in a vacuum circulation system, natural gas repeatedly flows through a pipeline equipped with a molecular sieve, so that light hydrocarbons in the natural gas are enriched in the molecular sieve; in the vacuum circulation system, the molecular sieve enriched with light hydrocarbons is heated, and the light hydrocarbons released by the molecular sieve are collected; wherein the light hydrocarbons are C5 hydrocarbons, C6 hydrocarbons, C7 hydrocarbons and C8 hydrocarbons. The present invention can obtain pure C5-C8 light hydrocarbon gas from natural gas with very little light hydrocarbon content by constructing a circulation system with an #imgabs0# molecular sieve. The method is simple, low in cost, easy to operate and high in acquisition efficiency.

Description

Technical Field

[0001] The invention relates to the field of gas geochemical analysis, and in particular to a method and system for collecting light hydrocarbons in natural gas. Background Art

[0002] Light hydrocarbons (C 5 -C 8 ) is one of the important components of natural gas and contains extremely important and rich geochemical information. The geochemical indicators of light hydrocarbons can not only be used to determine the maturity of natural gas, identify gas reservoirs that have been washed or biodegraded, and trace the source of natural gas, but also classify the genesis type of natural gas.

[0003] Crude oil samples contain a large number of volatile light hydrocarbon components, so light hydrocarbon components can be analyzed using gas chromatography or high performance liquid chromatography; however, the content of light hydrocarbon components in natural gas is extremely low, especially in "dry gas", where the methane content is as high as 95% or more, while other hydrocarbon components are very small. As a result, when gas chromatography is used for detection, only a few components such as methane and ethane can be detected. Light hydrocarbon components (C 5 -C 8 ) content cannot be detected because it does not reach the chromatographic detection limit. Due to the limitations of analytical technology, the scientific research on light hydrocarbon components in natural gas has developed slowly, not as fast as the research on light hydrocarbons in crude oil and source rocks, which has hindered the gas-oil-source comparison work in geological science. Therefore, how to use gas chromatograph to accurately and conveniently analyze trace light hydrocarbons in natural gas has become a focus of analytical testing technology.

[0004] To detect light hydrocarbon components in natural gas, the natural gas must first be pre-treated for light hydrocarbon enrichment. The current gas elution method, thermal evaporation method, rock sealed extraction, rock low-boiling point light hydrocarbon extraction method, and adsorption-acid hydrolysis hydrocarbon analysis method are only applicable to crude oil and source rock samples with high light hydrocarbon content. The pressurized sampling method designed by Xu Lian (1990) is only suitable for the analysis of natural gas with high humidity, and it is necessary to heat the natural gas cylinder to 120°C, which poses a great safety hazard; the quartz tube enrichment method disclosed by Zhang Juhe et al. (1994) collects a limited amount of natural gas, and the six-way valve part is prone to errors, and it is also impossible to accurately detect light hydrocarbon components. In recent years, there have been studies on the use of solid phase microextraction (SPME) technology for light hydrocarbon analysis in natural gas (Li et al. 2014), but the method is not mature yet and cannot detect light hydrocarbon components in natural gas. Wang Shunyu et al. published a natural gas C 3 -C 8 A new method for hydrocarbon concentration analysis, which uses a self-made C-type gas analyzer to directly collect natural gas concentration samples at the wellhead on site. 3 -C 8Hydrocarbon concentrator, but during detection, it is still necessary to elute the impurity gases such as methane and ethane in the concentrator. Summary of the invention

[0005] In order to achieve efficient, simple, convenient, safe and accurate analysis and testing of trace light hydrocarbon components in natural gas samples, provide more reliable experimental data for geochemical research, conduct scientific research on light hydrocarbon components and light hydrocarbon geochemical indicators in natural gas, and promote the gas-oil-source comparison work in geological science, the present invention has established a set of devices and methods for cyclic enrichment of fixed volume of natural gas using molecular sieves, and can collect enriched light hydrocarbon components online and transfer them to gas chromatography for analysis. The device and method can simply, conveniently, safely, accurately and efficiently enrich trace light hydrocarbon components in natural gas.

[0006] To achieve the technical purpose of the present invention, the present invention provides a method for collecting light hydrocarbons in natural gas in a laboratory, comprising:

[0007] Natural gas repeatedly flows through a pipeline equipped with molecular sieves in a vacuum circulation system, so that light hydrocarbons in the natural gas are enriched in the molecular sieves;

[0008] In a vacuum circulation system, the molecular sieve enriched with light hydrocarbons is heated and the light hydrocarbons released by the molecular sieve are collected.

[0009] Wherein, the light hydrocarbons are C5 hydrocarbons, C6 hydrocarbons, C7 hydrocarbons and C8 hydrocarbons.

[0010] Wherein, the vacuum circulation system is a vacuum pipeline connected in series with a molecular sieve;

[0011] Particularly, the vacuum pipeline is provided with an air pump and a vacuum pump.

[0012] The pipeline containing the molecular sieve may be a U-shaped pipe, or other pipelines capable of increasing the contact area between the natural gas and the molecular sieve and allowing gas to flow.

[0013] In particular, the molecular sieve is Molecular sieve.

[0014] In particular, in order to provide the vacuum pipeline with a good vacuum environment, the present application sets a vacuum pump at one end of the vacuum pipeline, and sets a valve on the pipeline connecting the vacuum pump and the pipeline.

[0015] In order to visually observe the vacuum environment of the pipeline, the present application sets a vacuum gauge at the other end of the vacuum pipeline to indicate the vacuum environment of the pipeline.

[0016] The air pump is arranged at one end close to the vacuum gauge. When the pipeline forms a circulation loop and the air pump is turned on, the air pressure difference of the air pump can cause the airflow in the pipeline to circulate in a directional manner, thereby realizing the circulation of natural gas.

[0017] The pipeline equipped with the molecular sieve is arranged in the middle section of the vacuum pipeline, so that the natural gas slowly flows into the pipeline equipped with the molecular sieve, and the filtered natural gas flowing out slowly flows into the natural gas storage device.

[0018] In particular, a gas extraction port is provided at one end of the pipeline equipped with the molecular sieve for collecting the gas released from the molecular sieve.

[0019] Particularly, valves for controlling airflow are provided at one end of the pipeline equipped with the molecular sieve and at the other end of the air intake port, for controlling the flow of airflow in the molecular sieve and the air intake port.

[0020] In order to achieve the technical purpose of the present invention, the present invention provides an online circulation system for collecting light hydrocarbons of natural gas in a laboratory, comprising:

[0021] Natural gas storage units;

[0022] A light hydrocarbon adsorption unit with a molecular sieve inside;

[0023] Light hydrocarbon extraction unit;

[0024] a circulation power unit disposed between the adsorption unit and the storage unit; and

[0025] The natural gas storage unit, the circulating power unit, the light hydrocarbon adsorption unit and the light hydrocarbon extraction unit are sequentially connected in series to form a vacuum pipeline of a circulating system.

[0026] Wherein, the vacuum pipeline is provided with an air pump and a vacuum pump, as well as a plurality of valves for controlling the airflow.

[0027] Wherein, the natural gas storage unit is any commercially available high-pressure steel cylinder with through valves at both ends.

[0028] The light hydrocarbon adsorption unit is a stainless steel tube with a molecular sieve inside, and the pipeline is a U-shaped tube, or a stainless steel tube that can increase the contact area between the natural gas and the molecular sieve and enable the gas to flow.

[0029] In particular, the molecular sieve used in the light hydrocarbon adsorption unit is Molecular sieve.

[0030] The present invention only utilizes Molecular sieves can adsorb light hydrocarbons in natural gas. They are made of single materials, are low-cost and easy to use.

[0031] Wherein, the light hydrocarbon extraction unit comprises:

[0032] A heating device arranged around the light hydrocarbon adsorption unit;

[0033] The gas inlet is arranged on the pipeline adjacent to the light hydrocarbon adsorption unit.

[0034] The heating device is any commercially available high-temperature furnace that can be placed on a stainless steel tube, and may have a temperature control function or an intelligent adjustment function.

[0035] The present invention can analyze the light hydrocarbons adsorbed in the adsorption unit by turning on the heating device, and the method is simple.

[0036] Wherein, the air intake port is sealed with a silicone pad.

[0037] When quantitative sampling of light hydrocarbons is required, the existing quantitative sampling equipment can be used to insert the rubber pad for extraction, or an external lead-out device can be used to quantitatively lead out the light hydrocarbons in the circulation system.

[0038] In particular, the light hydrocarbon collection unit can be connected to the detection system via an existing quantitative sampling device.

[0039] Wherein, the detection system is a gas chromatograph or other analytical equipment for analyzing light hydrocarbons.

[0040] In order to achieve the technical purpose of the present invention, the present invention also provides a method for using the above-mentioned laboratory method for collecting light hydrocarbons in natural gas for gas geochemical analysis.

[0041] The light hydrocarbon impurities collected by the method of the present invention are extremely low and high in content, and can meet the requirements of gas geochemical analysis.

[0042] In order to achieve the technical purpose of the present invention, the present invention also provides a chemical composition analysis device for light hydrocarbons in natural gas, which has the online circulation system for collecting light hydrocarbons in natural gas as claimed in the claims.

[0043] Beneficial Effects

[0044] The present invention is constructed by The molecular sieve circulation system can obtain pure C from natural gas with very little light hydrocarbon content. 5 -C 8 The light hydrocarbon gas is used for geochemical experimental analysis with simple method, low cost, easy operation, high acquisition efficiency and stable test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of the online circulation collection system for light hydrocarbons in natural gas provided in Example 1 of the present invention.

[0046] Figure 2 is a line graph showing the relationship between the molecular sieve adsorption component and time in the circulation system provided in Experimental Example 1 of the present invention;

[0047] Figure 3 A line graph showing the relationship between the adsorption of methane, ethane, isobutane and isopentane by the molecular sieve in the circulation system provided in Experimental Example 1 of the present invention and time;

[0048] Figure 4 A graph showing the relationship between the release amount of each component and the desorption temperature when the adsorption time is 30 min in the circulation system provided in Experimental Example 2 of the present invention;

[0049] Figure 5 The graph of the change in the gas component content of eight desorption temperatures when the adsorption time is 30 minutes in the circulation system provided in Test Example 2 of the present invention, wherein 1, methane; 2, ethane; 3, propane; 4, isobutane; 5, normal butane; 6, isopentane; 7, normal pentane; 8, 2,2-dimethylbutane; 9, cyclopentane + 2,3-dimethylbutane; 10, 2-methylpentane; 11, 3-methylpentane; 12, normal hexane; 13, methylcyclopentane.

[0050] Figure 1 Among them, 1. natural gas storage unit, 11. high-pressure steel cylinder, 12. connecting piece; 2. light hydrocarbon adsorption unit, 21. molecular sieve; 3. light hydrocarbon extraction unit, 31. heating device, 32. gas intake port, 321. connecting piece 322. silicone pad; 4. circulation power unit; 5. vacuum pipeline, 51. vacuum gauge, 52. vacuum pump, 53. valve, 54. valve, 55. valve. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with specific embodiments and test examples. It should be understood that these embodiments and test examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0052] The present invention will be described below with reference to specific embodiments and test examples, it should be noted that these embodiments and test examples are merely illustrative and cannot be construed as limiting the present invention. If not otherwise specified, the technical means adopted in the embodiments and test examples are conventional means well known to those skilled in the art, and the reagents and products adopted are also commercially available. Various processes and methods not described in detail are conventional methods well known in the art, and the source, trade name, and those who are necessary to list their constituents of the reagents used are all indicated when they first appear, and the same reagents used thereafter, if not otherwise specified, are identical with the content indicated for the first time.

[0053] Example 1 Online circulation collection system for light hydrocarbons in natural gas

[0054] like Figure 1 As shown, the online circulation collection system of light hydrocarbons in natural gas provided by the present invention comprises: a natural gas storage unit 1; a light hydrocarbon adsorption unit 2; a light hydrocarbon extraction unit 3; a circulation power unit 4; and a vacuum pipeline 5 having a valve 51 and a vacuum pump 52.

[0055] Furthermore, the natural gas storage unit 1 includes a high-pressure steel cylinder 11 for storing natural gas and a connector 12 for connecting the high-pressure steel cylinder 11 to the vacuum pipeline.

[0056] Specifically, the high-pressure steel cylinder 11 storing natural gas is a high-pressure steel cylinder conventionally used in the art, with through valves 13 at both ends, such as the LPG stainless steel sampling steel cylinder sold by Jiangsu Huiston Electromechanical Technology Co., Ltd.

[0057] Specifically, the connector 12 is a commercially available stainless steel sealing joint that can be connected.

[0058] Furthermore, the light hydrocarbon adsorption unit 2 is a U-shaped tube, in which a molecular sieve 21 is installed.

[0059] Specifically, the molecular sieve is commercially available Molecular sieve.

[0060] Furthermore, the light hydrocarbon extraction unit 3 comprises a heating device 31 arranged around the light hydrocarbon adsorption unit; and a gas extraction port 32 arranged on a pipeline adjacent to the light hydrocarbon adsorption unit.

[0061] Specifically, the air intake port 32 is connected to the circulation system via a connecting piece 321 .

[0062] Specifically, the air intake port 32 can be closed by using a silicone pad 322 .

[0063] Specifically, the heating device 31 is any commercially available device that can heat the U-shaped tube, such as a high-temperature furnace, or any commercially available high-temperature furnace that can perform temperature control. The connecting piece 321 is any commercially available stainless steel sealing joint that can be connected.

[0064] Furthermore, the circulation power unit 4 is a commercially available micro air pump. The present invention utilizes the pressure difference generated at both ends of the micro air pump to cause the airflow in the system to circulate in a directional manner.

[0065] Furthermore, the vacuum pipeline 5 connects the natural gas storage unit 1, the circulation power unit 4, the light hydrocarbon adsorption unit 2 and the light hydrocarbon extraction unit 3 in series in sequence into a circulation system, and utilizes the circulation power unit 4 to make the natural gas circulate in the natural gas storage unit 1 and the light hydrocarbon adsorption unit 2 in one direction.

[0066] Specifically, the vacuum pipeline 5 is provided with a vacuum gauge 51 , a vacuum pump 52 , and a valve 53 arranged in sequence between the circulation power unit 4 and the light hydrocarbon adsorption unit 2 , and a valve 54 and a valve 55 on the pipeline between the gas intake 32 and the natural gas storage unit 1 .

[0067] Specifically, the vacuum gauge 51 is used to indicate the vacuum level in the circulation system, the vacuum pump 52 is used to build a vacuum environment in the circulation system and can also discharge impurity gases, the valve 55 is used to control the opening and closing of the vacuum pump, and the valve 53 and the valve 54 are used to open and close the airflow at both ends of the light hydrocarbon adsorption unit 2.

[0068] Specifically, the vacuum pipelines used in the present invention are all commercially available stainless steel pipes. In one embodiment of the present invention, a 1 / 4 inch stainless steel pipe from Swagelok is used as the vacuum pipeline.

[0069] The structure adopted by the present invention is simple and low in cost, especially the adsorption carrier in the light hydrocarbon adsorption unit 2 only needs Molecular sieve can be used, which has a single component, is easy to replace and has low cost.

[0070] Example 2 Online Circulation Collection Method for Light Hydrocarbons in Natural Gas

[0071] The method for collecting light hydrocarbons in natural gas using the system provided in Example 1 is as follows:

[0072] 1. Installation and connection of natural gas storage device

[0073] First, the high-pressure steel cylinder 11 for collecting natural gas is connected to the circulating adsorption system using the connecting piece 12 according to the structural connection relationship provided in Example 1. At this time, the through valves 13 at both ends of the high-pressure steel cylinder are in a closed state.

[0074] 2. Air tightness inspection

[0075] Close the gas inlet and perform a leak test on the circulating adsorption system connected to the high-pressure steel cylinder 11 to check whether the airtightness of each part of the system is good. The leak test method adopts the conventional method in the field, by closing the valve 55, and observing whether the vacuum gauge changes. If the vacuum gauge reading does not change much, it is judged that the airtightness of the circulating system is good. If the vacuum gauge reading becomes larger, it means that the airtightness of the system is poor.

[0076] 3. Build a vacuum circulation system

[0077] Start the vacuum pump 52, open the pipeline valve 53, valve 54 and valve 55, and when the vacuum gauge shows When the valve 55 is closed, the air in the system is completely evacuated. Then slowly open the through valves 13 at both ends of the high-pressure cylinder, and at the same time turn on the micro air pump 4. Due to the pressure difference at both ends of the air pump, the natural gas in the system circulates in a directional manner.

[0078] 4. Adsorption of light hydrocarbons in natural gas

[0079] Due to the action of the micro air pump 4, natural gas flows out from one end of the high-pressure steel cylinder 11, flows through the U-shaped tube 2 along the vacuum pipeline 5, and then flows into the vacuum tube 5. Molecular sieves, The molecular sieve adsorbs the light hydrocarbons in the natural gas, and the remaining natural gas returns to the high-pressure steel cylinder 11. When the natural gas continuously flows out of the high-pressure steel cylinder, it passes through the U-shaped tube 2 and then continuously flows into the high-pressure steel cylinder 11, so that the natural gas and The molecular sieve is repeatedly contacted, and the light hydrocarbons in the natural gas are constantly Enriched in molecular sieves.

[0080] 5. Extraction of light hydrocarbons in natural gas

[0081] When the light hydrocarbon adsorption is completed, first open valve 55, and start vacuum pump 52 to discharge the impurity gas. Then close valve 53 and valve 54, turn on heating device 31 to heat the U-tube, so that the light hydrocarbon components adsorbed by the molecular sieve are desorbed. After heating for a period of time, use existing quantitative sampling equipment to take light hydrocarbon gas from the gas intake port, for example, use an external device with a fixed volume of saturated salt water to connect the gas intake port to quantitatively take light hydrocarbons. Since the light hydrocarbons taken by the method of the present invention are of high purity, the light hydrocarbons collected from the gas intake port can be directly used for gas chromatography detection, thereby performing gas geochemical analysis.

[0082] Application Examples

[0083] A high-pressure steel cylinder with a capacity of 1 L was connected to the circulating adsorption system of Example 1. The U-shaped tube in the circulating system contained 3 g of Molecular sieve, using the method provided in Example 2 to separate and extract light hydrocarbons.

[0084] Specifically, the adsorption time is 30-60 minutes, the impurity gas discharge time is 30 seconds, the heating temperature is less than 300° C., and the heating time is 2 minutes.

[0085] After testing, the impurity gases are methane, ethane, propane, isobutane and n-butane; the gases taken from the gas outlet are isopentane, n-pentane, 2,2-dimethylbutane, cyclopentane + 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane and methylcyclopentane.

[0086] It can be seen that the online circulation collection system for light hydrocarbons in natural gas provided by the present invention can efficiently and accurately collect light hydrocarbon gas in natural gas with extremely low content.

[0087] The following are some tests carried out during the development of the present invention, which are as follows:

[0088] Test Example 1: Adsorption effect test of each component at different adsorption times

[0089] To study the circulatory system Different adsorption times were selected to test the adsorption behavior of molecular sieve on light hydrocarbon components of natural gas, namely: 5min., 10min., 30min., 60min., 150min., 300min., and the desorption temperature of the sample ranged from 150℃ to 500℃, divided into eight temperature points of 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, and 500℃. The injection volume for chromatographic detection was 0.5mL. In order to avoid various accidental errors caused by a single injection, the samples collected in each adsorption time period were tested repeatedly (n≥5) and the average value was taken. After the molecular sieve has passed through different adsorption times, the total amount of light hydrocarbons adsorbed is the sum of the amount of gas analyzed at each temperature point. The experimental data are shown in Table 1. Figure 2 and Figure 3 shown.

[0090] Table 1 Adsorption content of each component of molecular sieve at different adsorption times

[0091]

[0092] Note: The amount of the component is expressed by the area of ​​the chromatographic peak (mV*s). The data in the table are the sum of the amount of gas desorbed by each component at six temperature points: 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ and 500℃.

[0093] According to Table 1 and Figure 1 The results show that the adsorption of propane, n-butane, n-pentane, 2,2-dimethylbutane, cyclopentane + 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane, and methylcyclopentane by molecular sieves increases with time before 60 minutes, reaches the maximum between 30 and 60 minutes, and then decreases with the increase of adsorption time. This shows that the adsorption of these components by molecular sieves is unimodal over time. Although the adsorption of methane, ethane, isobutane, and isopentane by molecular sieves fluctuates greatly over time, such as Figure 2 As shown in the figure, the change trend of the total amount of molecular sieve adsorption at the same adsorption time is still the largest between 30-60 minutes. After 60 minutes, the adsorption amount begins to decrease. It can be seen that after the molecular sieve adsorption reaches equilibrium, diffusion begins.

[0094] according to Figure 2 It can also be seen that the adsorption of methane is the least at 30 minutes, and the other components basically reach the maximum adsorption at 30 minutes. Therefore, setting the adsorption time at 30 minutes can effectively filter out the main components (CH 4 ), thereby achieving the purpose of light hydrocarbon concentration.

[0095] Through the above analysis, it can be concluded that the optimal adsorption time is 30min.

[0096] Experimental Example 2: Content of each component released at different desorption temperatures

[0097] According to the test analysis results of Test Example 1, the applicant desorbed the hydrocarbons adsorbed in the molecular sieve in the circulation system at eight temperature points of 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, and 500°C, and the temperature error was controlled within ±10°C. The component data obtained are shown in Table 2, Figure 4 .

[0098] Table 2 Content of each component released at different desorption temperatures

[0099]

[0100] Note: The data in the table are the peak areas of each component in the chromatogram (mV*s)

[0101] According to Table 2 and Figure 4 It can be seen that when the desorption temperature is 300℃, the total amount of gas released is the largest. The amount of gas released before 300℃ gradually increases; after the desorption temperature exceeds 300℃, the amount of gas desorbed decreases sharply. This shows that at 300℃, most of the light hydrocarbon components adsorbed by the molecular sieve can be released.

[0102] according to Figure 5 The curve of the release amount of each component in the molecular sieve with the desorption temperature shows that the desorption amount of components such as methane, ethane, isopentane, and 2,2-dimethylbutane decreases with the increase of desorption temperature, and isobutane has been basically released before 300°C. This shows that these components can be released from the molecular sieve at a lower desorption temperature. The desorption amount of components such as propane, n-butane, n-pentane, and n-hexane reaches the maximum at 300°C. The methane content in the gas after adsorption is significantly reduced, indicating that the 5A molecular sieve also has the function of filtering out methane and concentrating light hydrocarbons.

[0103] Depend on Figure 5It can also be seen that the content of methane and ethane in the gas desorbed at 300℃ and 350℃ is the lowest, and the content of components after isopentane in the desorbed gas gradually increases with the increase of temperature, and the higher the carbon number of the component, the more obvious the effect of its content increasing with the increase of temperature. The reason is that the thermodynamic properties of high carbon number hydrocarbon molecules determine that it requires a higher desorption temperature to leave the molecular sieve. Compared with the original sample composition, the sample after adsorption by 5A molecular sieve has C 5 + The concentration of components increased significantly.

[0104] Test Example 3 Reproducibility test of molecular sieve enrichment effect

[0105] The present invention also tested during the experiment The reproducibility of the molecular sieve enrichment effect (repetition number n=7), the conditions selected are: adsorption time 30min., desorption temperature 300°C, and chromatographic detection conditions remain unchanged, the data are shown in Table 3. The standard deviation of all light hydrocarbon components is less than 0.4.

[0106] Table 3 5A molecular sieve enrichment repeated test

[0107]

[0108] Column: The data in the table are the percentage concentration (%) of the sample components tested by gas chromatograph.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for collecting light hydrocarbons in natural gas in a laboratory, characterized in that: include: Natural gas repeatedly flows through a pipeline equipped with molecular sieves in a vacuum circulation system, so that light hydrocarbons in the natural gas are enriched in the molecular sieves; In a vacuum circulation system, a molecular sieve enriched with light hydrocarbons is heated, and the light hydrocarbons released by the molecular sieve are collected; Wherein, the light hydrocarbons are C5 hydrocarbons, C6 hydrocarbons, C7 hydrocarbons, and C8 hydrocarbons.

2. The method for collecting light hydrocarbons in natural gas in a laboratory according to claim 1, characterized in that: The vacuum circulation system is a vacuum pipeline connected in series with a molecular sieve; Wherein, the vacuum pipeline is provided with an air pump and a vacuum pump.

3. The method for collecting light hydrocarbons in natural gas in a laboratory according to any one of claims 1 or 2, characterized in that: The molecular sieve is a 5Å molecular sieve.

4. Use of the method for collecting light hydrocarbons in natural gas in a laboratory as described in any one of claims 1 to 3 for gas geochemical analysis.

Images