Sulfur isotope detection device system and method for organic sulfide in natural gas

Abstract

The invention relates to a sulfur isotope detection device system and method for organic sulfides in natural gas, impurities in the natural gas are removed through a preset chemical trap and a hydrogen sulfide adsorption trap coupled with a heating device for use, and the effective enrichment space of the organic sulfides in a cold trap is prevented from being occupied; two stages of cold traps are adopted, so that organic sulfides can be effectively enriched and detected and analyzed; the sulfur isotope detection device system is high in reliability, high in automation degree and easy to operate, sulfur isotope detection and analysis are carried out by combining a chromatography-stable isotope mass spectrometer, and a new way is provided for researching causes, sources and generation mechanisms of sulfur-containing natural gas.

Description

Technical Field

[0001] The present invention relates to the field of geochemical technology, and in particular to a sulfur isotope detection device system and method for organic sulfide in natural gas. Background Art

[0002] In the geological exploration of oil and gas, the stable sulfur isotope detection technology is widely used in the identification of oil and gas sources and the study of oil and gas reservoir formation. The pretreatment methods and sulfur isotope detection instrument conditions for different forms of sulfides in geological bodies are different. At present, there are three methods for determining sulfur isotopes: elemental analysis-stable isotope mass spectrometry, gas chromatography-stable isotope mass spectrometry, and gas chromatography-multi-collector inductively coupled plasma mass spectrometry.

[0003] Elemental analysis-stable isotope mass spectrometry can determine the sulfur isotopes of sulfides (acidic volatile sulfides, H2S, pyrite), elemental sulfur, sulfates (calcium sulfate, barium sulfate), and organic matter (kerogen, crude oil components). Different forms of sulfur-containing samples require different sample preparation methods: for sulfides, they are converted into silver sulfide, cadmium sulfide or zinc sulfide solids by adding acid (Tuttle et al., 1986; Acholla and Orr, 1993; Giesemann, 1994; Li Liwu et al., 2007; Liu Wenhui et al., 2015; Shawar, 2018); for elemental sulfur, it is extracted with chloroform solvent and converted into copper sulfide powder by adding copper powder (Zhang Zhongning et al., 2011); for sulfates, barium sulfate precipitates are formed with barium chloride under acid conditions (Tuttle et al., 1986; Acholla and Orr, 1993; Zhao Rui et al., 1996; Gao Jianfei et al., 2020); for sulfur in organic matter samples such as kerogen / asphalt, acid and oxidant need to be added to remove pyrite in the sample (Shawar et al., 2018, 2020). The prepared sample enters the elemental analyzer, is oxidized to SO2, and then enters the stable isotope mass spectrometer for sulfur isotope detection.

[0004] Gas chromatography-stable isotope mass spectrometry is to directly pass the purified carbonyl sulfide (O=C=S) into the mass spectrometer for ionization and detect the ion fragments. 32 S+, 33 S+ and 34 S+, to obtain the isotope value of sulfur (Hattori, 2015). This technology is only applicable to one compound (COS) and cannot be applied to other organic sulfur compounds in natural gas, so its application is very limited.

[0005] Gas chromatography-multi-collector inductively coupled plasma mass spectrometry can detect the sulfur isotopes of individual organic sulfur compounds. The main principle of this method is that after the organic sulfide is separated by a gas chromatograph, the analyte is transmitted to the multi-collector inductively coupled plasma mass spectrometry system through a heated transmission line, and the system measures the sulfur isotope composition of the individual compound peak. Multi-collector inductively coupled plasma mass spectrometry has high resolution and can analyze the δ34S value in a single organic sulfur compound at the picomolar (pmol) level, thus requiring less enrichment of the sample, but it is expensive, cumbersome to maintain and poorly popularized.

[0006] Stable isotope mass spectrometers are widely used, but they have high requirements for sample processing and require larger and purer organic sulfur fractions, which puts higher requirements on the pretreatment of organic sulfides. Sour natural gas is rich in acidic gases such as CO2 and H2S with high sulfur content, and their concentration can reach the percentage level, while the concentration of organic sulfides is usually at the ppm level. CO2 and H2S have similar enrichment temperatures to organic sulfides, and enrichment will occupy the effective enrichment space of organic sulfides in the cold trap; secondly, after the enrichment is completed, the product usually contains extremely high sulfur hydrogen sulfide. After entering the chromatographic column, there will be severe overload / tailing of sulfides, which seriously affects the measurement of organic sulfides with ppm content.

[0007] Therefore, in view of the shortcomings of the existing technology, there is an urgent need to provide a device system that has strong reliability, high degree of automation, simple operation, and can efficiently enrich organic sulfide and perform sulfur isotope detection. Summary of the invention

[0008] The purpose of the present invention is to provide a sulfur isotope detection device system and method for organic sulfide in natural gas, which realizes the efficient enrichment and purification of organic sulfide from sour natural gas, combines chromatography-stable isotope mass spectrometry to perform sulfur isotope detection and analysis, and provides a new way to study the cause, source and generation mechanism of sour natural gas.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a sulfur isotope detection device system for organic sulfide in natural gas, the sulfur isotope detection device system comprising a sample gas pipeline, a four-way valve, a chemical trap, a hydrogen sulfide adsorption trap, a constant temperature device, a water trap, a first cold trap, a second cold trap and a chromatograph-stable isotope mass spectrometer; the four-way valve is circumferentially provided with a first port, a second port, a third port and a fourth port;

[0011] The thermostatic device is provided with a first eight-way valve and a second eight-way valve inside, wherein the first eight-way valve is provided with an a port, a b port, a c port, a d port, an e port, an f port, a g port and an h port in a circumferential direction; and the second eight-way valve is provided with a first port, a second port, a third port, a fourth port, a fifth port, a sixth port, a seventh port and an eighth port in a circumferential direction;

[0012] The sample gas pipeline is connected to the fourth port of the four-way valve through a pipeline, and a flow controller is arranged at the front end of the sample gas pipeline; the first port of the four-way valve is connected to the chemical trap through a pipeline; the two ends of the hydrogen sulfide adsorption trap are respectively connected to the chemical trap and the sixth interface of the second eight-way valve through a pipeline; the two ends of the water trap are respectively connected to the fifth interface of the second eight-way valve and the g interface of the first eight-way valve through a pipeline; the two ends of the first cold trap are respectively connected to the h interface and the c interface of the first eight-way valve through a pipeline to form an injection passage;

[0013] The b interface of the first eight-way valve is connected to the first carrier gas pipeline through a pipeline, and the two ends of the second cold trap are respectively connected to the a interface of the first eight-way valve and the eighth interface of the second eight-way valve through pipelines to form a first purge passage;

[0014] The second port of the four-way valve is connected to a second carrier gas pipeline through a pipeline to form a second purge passage;

[0015] The second interface of the second eight-way valve is connected to a third carrier gas pipeline through a pipeline, and the first interface is connected to the chromatograph-stable isotope mass spectrometer through a pipeline to form a third purge passage;

[0016] The fourth interface of the second eight-way valve is connected to a fourth carrier gas pipeline through a pipeline, and the third interface is connected to the e interface of the first eight-way valve through a pipeline to form a fourth purge passage;

[0017] The purge air inlet end of the water trap is connected to a fifth carrier gas pipeline through a pipeline to form a purge and water removal gas path.

[0018] The sulfur isotope detection device system provided by the present invention fundamentally removes acidic gases such as water, CO2 and H2S in natural gas through a preset chemical trap and a hydrogen sulfide adsorption trap coupled with a heating device, thereby avoiding occupying the effective enrichment space of organic sulfides in a cold trap; a two-stage cold trap is adopted, the inner diameter of the first cold trap is relatively large, so that the enriched gas flow can pass quickly to achieve rapid pre-enrichment, and the inner diameter of the second cold trap is relatively small, which is close to the diameter of the chromatographic column, and the pre-enriched fraction is secondary enriched in the second cold trap, so that the components of organic sulfides in the chromatographic column are more concentrated, and tailing is effectively reduced, thereby achieving efficient enrichment and purification of organic sulfides from natural gas, and combining with a chromatographic-stable isotope mass spectrometer for sulfur isotope detection and analysis, which provides a new way to study the cause, source and generation mechanism of sulfur-containing natural gas.

[0019] Preferably, a water adsorbent and a carbon dioxide curing agent are provided inside the chemical trap.

[0020] Preferably, the water adsorbent comprises magnesium perchlorate and / or calcium oxide.

[0021] Preferably, the carbon dioxide curing agent includes sodium hydroxide and / or potassium hydroxide.

[0022] The water adsorbent and the carbon dioxide curing agent are reagents commonly used in the art and will not affect the detection object in the sample to be detected.

[0023] Preferably, a selective adsorbent is disposed inside the hydrogen sulfide adsorption trap.

[0024] Preferably, the selective adsorbent comprises silica gel particles of 60-100 mesh, for example, 60 mesh, 70 mesh, 80 mesh, 90 mesh or 100 mesh, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the silica gel particles are silica gel particles obtained after being treated with a mixed solution of 50 g / L cadmium sulfate and 20 g / L boric acid, dried, and wetted with a glycerol aqueous solution.

[0026] Preferably, the glycerol aqueous solution is a 75% glycerol aqueous solution.

[0027] Preferably, the outer jacket of the hydrogen sulfide adsorption trap is provided with a heating device.

[0028] Preferably, the heating device comprises a tubular heating furnace.

[0029] Preferably, the working temperature of the selective adsorbent is 78-82°C, for example, 78°C, 79°C, 80°C, 81°C or 82°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] The hydrogen sulfide adsorption trap needs to be used with a supporting heating device so that the working temperature of the selective adsorbent is within a reasonable range and the hydrogen sulfide gas can be selectively adsorbed.

[0031] Preferably, the water trap is made of Teflon.

[0032] Preferably, the operating temperature of the thermostat is 160-180°C, for example, 160°C, 165°C, 170°C, 175°C or 180°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, the first cold trap and the second cold trap are both made of stainless steel tubes with passivated inner surfaces.

[0034] Preferably, the inner diameter of the first cold trap is 0.5-1 mm, and the inner diameter of the second cold trap is 0.3-0.7 mm.

[0035] The inner diameter of the first cold trap is 0.5-1 mm, for example, 0.5 mm, 0.75 mm, 0.8 mm or 1 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] The inner diameter of the first cold trap is 0.3-0.7 mm, for example, 0.3 mm, 0.38 mm, 0.5 mm or 0.7 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] The first cold trap has a larger inner diameter, which allows the enriched gas flow to pass quickly to achieve rapid pre-enrichment. The second cold trap has a smaller inner diameter, which is close to the diameter of the chromatographic column. The pre-enriched fraction is secondary enriched in the second cold trap, which can make the organic sulfide components in the chromatographic column more concentrated and effectively reduce tailing.

[0038] Preferably, adsorbent is disposed inside the first cold trap and the second cold trap.

[0039] Preferably, the adsorbent comprises any one of Hayesep N adsorbent, 5A molecular sieve, Tenax TA adsorbent or Tenax GR adsorbent, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of Hayesep N adsorbent and 5A molecular sieve, a combination of Tenax TA adsorbent and Tenax GR adsorbent, or a combination of Hayesep N adsorbent, 5A molecular sieve, Tenax TA adsorbent and Tenax GR adsorbent.

[0040] Preferably, the carrier gas introduced into the first carrier gas pipeline, the second carrier gas pipeline, the third carrier gas pipeline, the fourth carrier gas pipeline and the fifth carrier gas pipeline includes nitrogen and / or an inert gas.

[0041] Preferably, the inert gas includes any one of helium, neon or argon.

[0042] Preferably, the pipeline comprises a passivated quartz capillary.

[0043] In a second aspect, the present invention provides a method for using the sulfur isotope detection device system according to the first aspect, the method comprising the following steps:

[0044] The natural gas sample to be tested is subjected to impurity removal treatment, and the obtained impurity-removed sample gas is subjected to a first enrichment treatment and a second enrichment treatment to obtain organic sulfide; the obtained organic sulfide is subjected to a sulfur isotope detection treatment to obtain a sulfur isotope detection value.

[0045] The method provided by the present invention can realize efficient enrichment and purification of organic sulfides from natural gas for stable isotope detection by controlling the temperature, sample gas flow rate and injection time parameters in the first enrichment treatment and the second enrichment treatment.

[0046] Preferably, the enrichment temperatures of the first enrichment treatment and the second enrichment treatment are respectively -100 to -80°C, for example, -100°C, -95°C, -90°C, -85°C or -80°C, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] Preferably, the thermal desorption temperature after the first enrichment treatment and the second enrichment treatment is 158-162°C, for example, 158°C, 159°C, 160°C, 161°C or 162°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] The "thermal desorption" means that the first enrichment treatment and the second enrichment treatment are both in a frozen enrichment state. When the first enrichment treatment or the second enrichment treatment is completed, the frozen enrichment state is converted into a heated state, and the impurity-removed sample gas is released from the first cold trap or the second cold trap in the heated state, which is thermal desorption, and then enters the next-level device.

[0049] Preferably, the flow rate of the impurity-removing sample gas during the first enrichment treatment is 15-20 mL / min, for example, it can be 15 mL / min, 16 mL / min, 18 mL / min, 19 mL / min or 20 mL / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] Preferably, the injection time of the impurity-removing sample gas during the first enrichment treatment is 30-300s, for example, it can be 30s, 100s, 150s, 200s or 300s, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] Preferably, the flow rate of the impurity-removing sample gas during the second enrichment treatment is 5-10 mL / min, for example, it can be 5 mL / min, 6 mL / min, 8 mL / min, 9 mL / min or 10 mL / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] Preferably, the injection time of the impurity-removed sample gas during the second enrichment treatment is 30-60s, for example, 30s, 40s, 50s or 60s, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The sulfur isotope detection device system provided by the present invention fundamentally removes acidic gases such as water, CO2 and H2S in natural gas by presetting a chemical trap and a hydrogen sulfide adsorption trap coupled with a heating device, thereby avoiding occupying the effective enrichment space of organic sulfides in the cold trap; a two-stage cold trap is adopted, the first cold trap has a larger inner diameter, which allows the enriched gas flow to pass quickly to achieve rapid pre-enrichment, and the second cold trap has a smaller inner diameter, which is close to the diameter of the chromatographic column, so that the components of organic sulfides in the chromatographic column can be more concentrated, effectively reducing tailing;

[0055] (2) The sulfur isotope detection device system provided by the present invention has strong reliability, high degree of automation and simple operation. It can efficiently enrich and purify organic sulfides from natural gas through program control, and combine with chromatography-stable isotope mass spectrometry to perform sulfur isotope detection and analysis, providing a new way to study the cause, source and generation mechanism of sulfur-containing natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a schematic structural diagram of the first enrichment pathway provided in Example 1 of the present invention;

[0057] Figure 2 is a schematic structural diagram of the second enrichment pathway provided in Example 1 of the present invention;

[0058] Figure 3 is a schematic diagram of the structure of the sample injection detection path provided in Example 1 of the present invention;

[0059] Figure 4 This is a graph showing the sulfur isotope detection value results provided in Application Example 1 of the present invention;

[0060] Figure 5 This is a graph showing the sulfur isotope detection value results provided by Application Example 2 of the present invention;

[0061] Figure 6 This is a graph showing the sulfur isotope detection value results provided by Application Example 3 of the present invention;

[0062] Figure 7 This is a graph showing the sulfur isotope detection value results provided by Application Example 4 of the present invention;

[0063] Figure 8 This is a graph showing the sulfur isotope detection value results provided by Application Example 5 of the present invention;

[0064] Fig. 9 This is a graph showing the sulfur isotope detection value results provided in Comparative Application Example 1 of the present invention;

[0065] Fig.10 This is a graph showing the sulfur isotope detection value results provided by Comparative Application Example 2 of the present invention;

[0066] Wherein: 1, sample gas pipeline; 2, four-way valve; 3, chemical trap; 4, hydrogen sulfide adsorption trap; 5, constant temperature device; 6, Teflon water trap; 7, first cold trap; 8, second cold trap; 9, chromatography-stable isotope mass spectrometer; 10, first eight-way valve; 11, second eight-way valve; 12, first carrier gas pipeline; 13, second carrier gas pipeline; 14, third carrier gas pipeline; 15, fourth carrier gas pipeline; 16, fifth carrier gas pipeline; 17, flow controller; 18, tubular heating furnace;

[0067] 201, first port; 202, second port; 203, third port; 204, fourth port;

[0068] 1001, a interface; 1002, b interface; 1003, c interface; 1004, d interface; 1005, e interface; 1006, f interface; 1007, g interface; 1008, h interface;

[0069] 1101, first interface; 1102, second interface; 1103, third interface; 1104, fourth interface; 1105, fifth interface; 1106, sixth interface; 1107, seventh interface; 1108, eighth interface. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0071] Example 1

[0072] The present embodiment provides a sulfur isotope detection device system for organic sulfide in natural gas, the sulfur isotope detection device system comprising a sample gas pipeline 1, a four-way valve 2, a chemical trap 3, a hydrogen sulfide adsorption trap 4, a constant temperature device 5, a Teflon water trap 6, a first cold trap 7, a second cold trap 8 and a chromatograph-stable isotope mass spectrometer 9; the four-way valve 2 is circumferentially provided with a first port 201, a second port 202, a third port 203 and a fourth port 204;

[0073] The thermostatic device 5 is provided with a first eight-way valve 10 and a second eight-way valve 11 inside. The first eight-way valve 10 is provided with an a port 1001, a b port 1002, a c port 1003, a d port 1004, an e port 1005, an f port 1006, a g port 1007 and an h port 1008 in a circumferential direction. The second eight-way valve 11 is provided with a first port 1101, a second port 1102, a third port 1103, a fourth port 1104, a fifth port 1105, a sixth port 1106, a seventh port 1107 and an eighth port 1108 in a circumferential direction.

[0074] The b interface 1002 of the first eight-way valve 10 is connected to the first carrier gas pipeline 12 through a pipeline, and both ends of the second cold trap 8 are respectively connected to the a interface 1001 of the first eight-way valve 10 and the eighth interface 1108 of the second eight-way valve 11 through pipelines to form a first purge passage;

[0075] The second port 202 of the four-way valve 2 is connected to the second carrier gas pipeline 13 through a pipeline to form a second purge passage;

[0076] The second interface 1102 of the second eight-way valve 11 is connected to the third carrier gas pipeline 14 through a pipeline, and the first interface 1101 is connected to the chromatograph-stable isotope mass spectrometer 9 through a pipeline to form a third purge passage;

[0077] The fourth interface 1104 of the second eight-way valve 11 is connected to the fourth carrier gas pipeline 15 through a pipeline, and the third interface 1103 is connected to the e interface 1005 of the first eight-way valve 10 through a pipeline to form a fourth purge passage;

[0078] The purge air inlet end of the Teflon water trap 6 is connected to a fifth carrier gas pipeline 16 through a pipeline to form a purge and water removal gas path;

[0079] The carrier gas introduced into the first carrier gas pipeline 12, the second carrier gas pipeline 13, the third carrier gas pipeline 14, the fourth carrier gas pipeline 15 and the fifth carrier gas pipeline 16 are all helium; the pipelines include quartz capillaries that have been passivated;

[0080] A flow controller 17 is provided at the front end of the sample gas pipeline 1; the sample gas pipeline 1 is connected in sequence to the fourth port 204 of the four-way valve 2, the chemical trap 3, the hydrogen sulfide adsorption trap 4, the sixth interface 1106 of the second eight-way valve 11, the Teflon water trap 6, the g interface 1007 of the first eight-way valve 10, the first cold trap 7 and the c interface 1003 of the first eight-way valve 10 to form an injection passage; the injection passage is a first enrichment passage, and the first carrier gas pipeline 12, the second carrier gas pipeline 13, the third carrier gas pipeline 14, the fourth carrier gas pipeline 15 and the fifth carrier gas pipeline 16 are all purge passages, and the structural schematic diagram is shown in FIG. Figure 1As shown;

[0081] The first carrier gas pipeline 12 is connected in sequence to the b interface 1002 of the first eight-way valve 10, the first cold trap 7, the a interface 1001 of the first eight-way valve 10, the second cold trap 8 and the eighth interface 1108 of the second eight-way valve 11 to form a second enrichment passage. The second carrier gas pipeline 13, the third carrier gas pipeline 14, the fourth carrier gas pipeline 15 and the fifth carrier gas pipeline 16 are all purge passages. The structural diagram is shown in FIG. Figure 2 As shown;

[0082] The first carrier gas pipeline 12 is connected in sequence to the b interface 1002 of the first eight-way valve 10, the a interface 1001 of the first eight-way valve 10, the second cold trap 8, the eighth interface 1108 of the second eight-way valve 11, the first interface 1101 of the second eight-way valve 11 and the chromatography-stable isotope mass spectrometer 9 to form an injection detection path. The second carrier gas pipeline 13, the third carrier gas pipeline 14, the fourth carrier gas pipeline 15 and the fifth carrier gas pipeline 16 are all purge paths. The structural schematic diagram is shown in FIG. Figure 3 As shown;

[0083] Magnesium perchlorate and sodium hydroxide are arranged inside the chemical trap 3;

[0084] The hydrogen sulfide adsorption trap 4 is provided with 80-mesh silica gel particles inside, the silica gel particles are treated with a mixed solution of 50 g / L cadmium sulfate and 20 g / L boric acid, and the silica gel particles are dried and then wetted with a 75% glycerol aqueous solution; the hydrogen sulfide adsorption trap 4 is provided with a tubular heating furnace 18 outside, and the working temperature of the silica gel particles is 80°C;

[0085] The working temperature of the thermostat 5 is 170°C;

[0086] The first cold trap 7 and the second cold trap 8 are both made of stainless steel tubes with passivated inner surfaces; the inner diameter of the first cold trap 7 is 0.75 mm, and the inner diameter of the second cold trap 8 is 0.5 mm; Hayesep N adsorbent is disposed inside the first cold trap 7 and the second cold trap 8.

[0087] Example 2

[0088] This embodiment provides a sulfur isotope detection device system for organic sulfide in natural gas, which is different from Embodiment 1 in that, except that the inner diameter of the first cold trap 7 is adjusted to 0.13 mm and the inner diameter of the second cold trap 8 is adjusted to 0.1 mm, the rest is the same as Embodiment 1.

[0089] Example 3

[0090] This embodiment provides a sulfur isotope detection device system for organic sulfide in natural gas, which is different from Embodiment 1 in that, except that the inner diameter of the first cold trap 7 is adjusted to 1.27 mm and the inner diameter of the second cold trap 8 is adjusted to 1.25 mm, the rest is the same as Embodiment 1.

[0091] Comparative Example 1

[0092] This comparative example provides a sulfur isotope detection device system for organic sulfide in natural gas, which is different from Example 1 in that the settings of the first cold trap 7 and the second cold trap 8 are adjusted to retain only the second cold trap 8, and the connection relationship of each pipeline is adaptively adjusted, and the rest is the same as Example 1.

[0093] Comparative Example 2

[0094] This comparative example provides a sulfur isotope detection device system for organic sulfide in natural gas, which is different from Example 1 in that the chemical trap 3 and the hydrogen sulfide adsorption trap 4 are not provided, and the rest are the same as Example 1.

[0095] Application Example 1

[0096] This application example provides a method for applying the sulfur isotope detection device system provided in Example 1, and the method includes the following steps:

[0097] The natural gas sample gas to be tested is subjected to impurity removal treatment, and the obtained impurity-removed sample gas is subjected to the first enrichment treatment and the second enrichment treatment to obtain organic sulfide; the obtained organic sulfide is subjected to sulfur isotope detection treatment to obtain the sulfur isotope detection value; the enrichment temperature of the first enrichment treatment is -90°C, the flow rate of the impurity-removed sample gas is 18mL / min, the injection time is 200s, and the first cold trap 7 is in a frozen enrichment state; after the first enrichment treatment, the first cold trap 7 is converted from a frozen enrichment state to a heating state, and the thermal desorption temperature is 160°C; the enrichment temperature of the second enrichment treatment is -90°C, the flow rate of the impurity-removed sample gas is 8mL / min, the injection time is 50s, and the second cold trap 8 is in a frozen enrichment state; after the second enrichment treatment, the second cold trap 8 is converted from a frozen enrichment state to a heating state, and the thermal desorption temperature is 160°C.

[0098] Among them, the sulfur isotope detection process uses SO2 cylinder gas calibrated to the CDT standard by national standard materials (GBW04414, GBW04415) as the reference gas. The sulfur isotope detection value results are shown in the figure below. Figure 4 As shown in the figure, it can be seen that the peak shape of the compound is normally distributed, and the peak intensity is good, between 6000-6500mv;

[0099] The same natural gas sample was tested five times in parallel, as shown in Table 1. The average values ​​of thiophene, diethyl sulfide, dimethyl disulfide and other compounds were 27.4‰, 18.26‰ and 15.7‰, respectively, and the standard deviations were all less than 0.5‰. The test stability was good and the results were accurate.

[0100] Table 1

[0101]

[0102]

[0103] Application Example 2

[0104] This application example provides a method for applying the sulfur isotope detection device system provided in Example 1. The difference from Application Example 1 is that the enrichment temperature of the first enrichment treatment is adjusted to -100°C, the flow rate of the impurity-removing sample gas is adjusted to 20mL / min, the injection time is adjusted to 30s, and the thermal desorption temperature is adjusted to 158°C; the enrichment temperature of the second enrichment treatment is adjusted to -100°C, the flow rate of the impurity-removing sample gas is adjusted to 10mL / min, the injection time is adjusted to 30s, and the thermal desorption temperature is adjusted to 158°C. The rest are the same as Application Example 1.

[0105] The sulfur isotope detection results are shown in the figure below: Figure 5 As shown in the figure, it can be seen that the compound has a good peak shape, but the peak intensity is significantly reduced. The sulfur isotope detection values ​​of the three organic sulfides are 27.34‰, 18.56‰, and 15.67‰, respectively. The measured values ​​are not much different from the average values ​​of Example 1.

[0106] Application Example 3

[0107] This application example provides a method for applying the sulfur isotope detection device system provided in Example 1. The difference from Application Example 1 is that the enrichment temperature of the first enrichment treatment is adjusted to -80°C, the flow rate of the impurity-removing sample gas is adjusted to 15mL / min, the injection time is adjusted to 300s, and the thermal desorption temperature is adjusted to 162°C; the enrichment temperature of the second enrichment treatment is adjusted to -80°C, the flow rate of the impurity-removing sample gas is adjusted to 5mL / min, the injection time is adjusted to 60s, and the thermal desorption temperature is adjusted to 162°C. The rest are the same as Application Example 1.

[0108] The sulfur isotope detection results are shown in the figure below: Figure 6 As shown in the figure, it can be seen that the compound has a good peak shape and a reduced peak intensity. The sulfur isotope detection values ​​of the three organic sulfides are 27.47‰, 18.29‰, and 15.16‰, respectively. The measured values ​​are not much different from the average values ​​of Example 1.

[0109] Application Example 4

[0110] This application example provides a method for applying the sulfur isotope detection device system provided in Example 2, and the steps of the method are the same as those of Application Example 1.

[0111] Since the inner diameters of the first and second cold traps are too small, the amount of organic sulfur enriched in the cold traps is too small. The sulfur isotope detection results are shown in the figure below. Figure 7 As shown in the figure, it can be seen that only the first compound peak appears, and the peak intensity is too low. Only the first organic sulfide sulfur isotope is detected, which is 11.04‰. The measured value is greatly different from the average value of the first compound in Example 1.

[0112] Application Example 5

[0113] This application example provides a method for applying the sulfur isotope detection device system provided in Example 3, and the steps of the method are the same as those of Application Example 1.

[0114] Since the inner diameters of the first and second cold traps are too large, the peak shape of the organic sulfide shows severe tailing, the peak time is delayed, and the peak intensity is significantly reduced. The sulfur isotope detection value results are shown in the figure below: Figure 8 As shown in the figure, it can be seen that the sulfur isotope detection values ​​of the three organic sulfides are 22.32‰, 13.17‰, and 12.01‰, respectively. The measured values ​​are greatly different from the average values ​​in Example 1.

[0115] Comparative application example 1

[0116] This comparative application example provides a method for applying the sulfur isotope detection device system provided in Comparative Example 1. The steps of the method differ from those of Application Example 1 in that there is no first enrichment treatment step, and the rest are the same as Application Example 1.

[0117] Compared with the two-step enrichment treatment, the direct one-step enrichment treatment will result in too low an amount of enriched organic sulfide. The sulfur isotope detection value results are shown in the figure below. Fig. 9 As shown in the figure, it can be seen that the peak intensity of the compound is significantly reduced, and the sulfur isotope detection values ​​of the three organic sulfides are 22.39‰, 14.14‰, and 11.76‰, respectively. The measured values ​​are greatly different from the average values ​​of Example 1.

[0118] Comparative Application Example 2

[0119] This comparative application example provides a method for applying the sulfur isotope detection device system provided in comparative example 2. The steps of the method differ from those of application example 1 in that there is no impurity removal step, and the rest are the same as application example 1.

[0120] Without impurity removal, acidic gases such as water, CO2 and H2S in natural gas occupy the effective enrichment space of organic sulfides in the cold trap, resulting in the enrichment of hydrogen sulfide and other gases in natural gas entering the mass spectrometer. The sulfur isotope detection value results are shown in the figure below. Fig.10 As shown in the figure, it can be seen that before the first organic sulfur compound peak, there appears an overload peak, which is a hydrogen sulfide peak with an intensity exceeding 35,000 mv and an obvious tailing, while the peak intensity of the subsequent target organic sulfide is too low, and the three target organic sulfide sulfur isotope values ​​cannot be detected.

[0121] In summary, the sulfur isotope detection device system provided by the present invention fundamentally removes acidic gases such as water, CO2 and H2S in natural gas through a preset chemical trap and a hydrogen sulfide adsorption trap coupled with a heating device, thereby avoiding occupying the effective enrichment space of organic sulfides in the cold trap; a two-stage cold trap is adopted, the first cold trap has a larger inner diameter, which allows the enriched gas flow to pass quickly to achieve rapid pre-enrichment, and the second cold trap has a smaller inner diameter, which is close to the diameter of the chromatographic column, so that the components of organic sulfides in the chromatographic column can be more concentrated, effectively reducing tailing;

[0122] The sulfur isotope detection device system provided by the present invention has strong reliability, high degree of automation and simple operation. It can efficiently enrich and purify organic sulfides from natural gas through program control, and combine with chromatography-stable isotope mass spectrometry to perform sulfur isotope detection and analysis, providing a new approach to studying the cause, source and generation mechanism of sulfur-containing natural gas.

[0123] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A sulfur isotope detection device system for organic sulfide in natural gas, characterized in that: The sulfur isotope detection device system comprises a sample gas pipeline, a four-way valve, a chemical trap, a hydrogen sulfide adsorption trap, a constant temperature device, a water trap, a first cold trap, a second cold trap and a chromatograph-stable isotope mass spectrometer; The four-way valve is circumferentially provided with a first port, a second port, a third port and a fourth port; The thermostatic device is provided with a first eight-way valve and a second eight-way valve inside, wherein the first eight-way valve is provided with an a port, a b port, a c port, a d port, an e port, an f port, a g port and an h port in a circumferential direction; and the second eight-way valve is provided with a first port, a second port, a third port, a fourth port, a fifth port, a sixth port, a seventh port and an eighth port in a circumferential direction; The sample gas pipeline is connected to the fourth port of the four-way valve through a pipeline, and a flow controller is arranged at the front end of the sample gas pipeline; the first port of the four-way valve is connected to the chemical trap through a pipeline; the two ends of the hydrogen sulfide adsorption trap are respectively connected to the chemical trap and the sixth interface of the second eight-way valve through a pipeline; the two ends of the water trap are respectively connected to the fifth interface of the second eight-way valve and the g interface of the first eight-way valve through a pipeline; the two ends of the first cold trap are respectively connected to the h interface and the c interface of the first eight-way valve through a pipeline to form an injection passage; The b interface of the first eight-way valve is connected to the first carrier gas pipeline through a pipeline, and the two ends of the second cold trap are respectively connected to the a interface of the first eight-way valve and the eighth interface of the second eight-way valve through pipelines to form a first purge passage; The second port of the four-way valve is connected to a second carrier gas pipeline through a pipeline to form a second purge passage; The second interface of the second eight-way valve is connected to a third carrier gas pipeline through a pipeline, and the first interface is connected to the chromatograph-stable isotope mass spectrometer through a pipeline to form a third purge passage; The fourth interface of the second eight-way valve is connected to a fourth carrier gas pipeline through a pipeline, and the third interface is connected to the e interface of the first eight-way valve through a pipeline to form a fourth purge passage; The purge air inlet end of the water trap is connected to a fifth carrier gas pipeline through a pipeline to form a purge and water removal gas path.

2. The sulfur isotope detection device system according to claim 1, characterized in that: The chemical trap is provided with a water adsorbent and a carbon dioxide curing agent inside; Preferably, the water adsorbent comprises magnesium perchlorate and / or calcium oxide; Preferably, the carbon dioxide curing agent includes sodium hydroxide and / or potassium hydroxide.

3. The sulfur isotope detection device system according to claim 1 or 2, characterized in that: A selective adsorbent is disposed inside the hydrogen sulfide adsorption trap; Preferably, the selective adsorbent comprises 60-100 mesh silica gel particles; Preferably, the silica gel particles are silica gel particles obtained after being treated with a mixed solution of cadmium sulfate and boric acid, dried, and wetted with a glycerol aqueous solution.

4. The sulfur isotope detection device system according to any one of claims 1 to 3, characterized in that: The outer sleeve of the hydrogen sulfide adsorption trap is provided with a heating device; Preferably, the operating temperature of the selective adsorbent is 78-82°C; Preferably, the operating temperature of the thermostat is 160-180°C.

5. The sulfur isotope detection device system according to any one of claims 1 to 4, characterized in that: The first cold trap and the second cold trap are both made of stainless steel pipes with passivated inner surfaces; Preferably, the inner diameter of the first cold trap is 0.5-1 mm, and the inner diameter of the second cold trap is 0.3-0.7 mm; Preferably, adsorbent is disposed inside the first cold trap and the second cold trap; Preferably, the adsorbent includes any one of Hayesep N adsorbent, 5A molecular sieve, Tenax TA adsorbent or Tenax GR adsorbent, or a combination of at least two thereof.

6. The sulfur isotope detection device system according to any one of claims 1 to 5, characterized in that: The carrier gas introduced into the first carrier gas pipeline, the second carrier gas pipeline, the third carrier gas pipeline, the fourth carrier gas pipeline and the fifth carrier gas pipeline includes nitrogen and / or an inert gas; Preferably, the pipeline comprises a passivated quartz capillary.

7. A method for using the sulfur isotope detection device system according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: The natural gas sample to be tested is subjected to impurity removal treatment, and the obtained impurity-removed sample gas is subjected to a first enrichment treatment and a second enrichment treatment to obtain organic sulfide; the obtained organic sulfide is subjected to a sulfur isotope detection treatment to obtain a sulfur isotope detection value.

8. The method according to claim 7, characterized in that The enrichment temperatures of the first enrichment treatment and the second enrichment treatment are respectively -100 to -80°C; Preferably, the thermal desorption temperatures after the first enrichment treatment and the second enrichment treatment are 158-162° C. respectively.

9. The method according to claim 7 or 8, characterized in that: The flow rate of the impurity-removing sample gas during the first enrichment treatment is 15-20 mL / min; Preferably, the injection time of the impurity-free sample gas during the first enrichment treatment is 30-300s.

10. The method according to any one of claims 7 to 9, characterized in that: The flow rate of the impurity-removing sample gas during the second enrichment treatment is 5-10 mL / min; Preferably, the injection time of the impurity-free sample gas during the second enrichment treatment is 30-60s.

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