A device for preparing rare gas samples by oxidizing natural gas and a method for using the same

Abstract

The present invention relates to a device for preparing rare gas samples by oxidizing natural gas, the device comprising a high vacuum system, a tubular electric furnace and a rare gas mass spectrometer system; the high vacuum system is connected to a pipeline II via a pipeline I, one end of the pipeline II is connected to a natural gas inlet, and the other end thereof passes through the tubular electric furnace and is connected to a pipeline III; a metal high vacuum valve I is provided on the pipeline I; a metal high vacuum valve II, a metal high vacuum valve III, a metal quartz conversion joint I, and an activated carbon cold finger I are respectively provided on the pipeline II; the end of the pipeline III is connected to the rare gas mass spectrometer system; the pipeline III is respectively provided with a metal quartz conversion joint II, a metal high vacuum valve IV, and an activated carbon cold finger II. The present invention also discloses a method for using the device. The detection result of the present invention is accurate and reliable, and can meet the need for preparing more rare gas isotope samples, thereby reducing the requirement for the detection sensitivity of the rare gas isotope mass spectrometer.

Description

Technical Field

[0001] The invention relates to the technical field of rare gas isotopes, and in particular to a device for preparing rare gas samples by oxidizing natural gas and a use method thereof. Background Art

[0002] Rare gases include helium, neon, argon, krypton, xenon and radon. The stable isotope composition of helium, neon, argon, krypton and xenon is often analyzed by a rare gas mass spectrometer. In order to obtain accurate data, helium, neon, argon, krypton and xenon are usually prepared from gas samples and separated into pure components, and then the isotope composition of each component is analyzed by a rare gas mass spectrometer. The process of preparing a gas sample to contain only rare gases is also called purification.

[0003] The isotopic composition of noble gases in the sun, planets and the earth's spheres has different characteristics. Through analysis, the isotopic composition information of each noble gas can be obtained, thus providing a basis for studying the origin and evolution of the universe, planets and the earth. Natural gas is mainly hydrocarbon gas, and the content of noble gases is generally very low. In order to detect the isotopic composition of noble gases in natural gas, the natural gas must be purified into pure noble gases, and then the noble gas components are separated and the isotopic composition mass spectrometry is detected. The chemical reagents required for purification usually include sponge titanium, zirconium aluminum getter and activated carbon, and an electric furnace is used. Activated carbon has a good purification and separation effect on helium and neon isotope composition samples, but it is difficult to be used for the purification and separation of krypton and xenon isotope samples in natural gas. Sponge titanium and zirconium aluminum getter have a good absorption effect on non-hydrocarbon gases, but the absorption of hydrocarbon gases is very slow and difficult to completely absorb, especially heavy hydrocarbons. For natural gas samples with high heavy hydrocarbons, heavy hydrocarbons can also be removed by liquid nitrogen cold trap to prepare helium, neon and argon isotope composition samples, but they cannot be used to prepare xenon isotope composition samples. Since the content of krypton or xenon in natural gas is much lower than that of argon, the difficulty is more obvious when it is necessary to use the above method to prepare a large amount of krypton or xenon isotope composition samples. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a device for preparing rare gas samples by oxidizing natural gas with accurate and reliable detection results.

[0005] Another technical problem to be solved by the present invention is to provide a method for using the device for preparing rare gas samples by oxidizing natural gas.

[0006] In order to solve the above problems, the device for preparing rare gas samples by oxidizing natural gas described in the present invention is characterized in that: the device includes a high vacuum system, a tubular electric furnace and a rare gas mass spectrometer system; the high vacuum system is connected to a pipeline II via a pipeline I, one end of the pipeline II is connected to a natural gas inlet, and the other end thereof passes through the tubular electric furnace and is connected to a pipeline III; a metal high vacuum valve I is provided on the pipeline I; a metal high vacuum valve II, a metal high vacuum valve III, a metal quartz conversion joint I, and an activated carbon cold finger I are respectively provided on the pipeline II; the end of the pipeline III is connected to the rare gas mass spectrometer system; a metal quartz conversion joint II, a metal high vacuum valve IV, and an activated carbon cold finger II are respectively provided on the pipeline III.

[0007] The activated carbon cold finger I is provided on the pipeline II between the metal high vacuum valve III and the metal quartz conversion joint I.

[0008] The pipeline I is provided on the pipeline II between the metal high vacuum valve II and the metal high vacuum valve III.

[0009] Asbestos baffles are provided at both ends of the tubular electric furnace, and the temperature thereof is controlled to be 400-900°C.

[0010] The activated carbon cold finger II is provided on the pipeline III between the metal quartz conversion joint II and the metal high vacuum valve IV.

[0011] The pipeline II between the metal quartz conversion joint I and the natural gas inlet, and the pipeline III between the metal quartz conversion joint II and the rare gas mass spectrometer system are both metal pipelines.

[0012] The pipeline II and the pipeline III between the metal quartz conversion joint I and the metal quartz conversion joint II are both quartz pipelines, and the quartz pipelines are filled with linear copper oxide.

[0013] The method for using the device for preparing rare gas samples by oxidizing natural gas as described above comprises the following steps:

[0014] ⑴ Close the metal high vacuum valve IV, open the metal high vacuum valve I, metal high vacuum valve II, and metal high vacuum valve III, and evacuate the high vacuum system; at the same time, heat the tubular electric furnace to 400℃;

[0015] (2) closing the metal high vacuum valve I, closing the metal high vacuum valve III, and quantitatively injecting a natural gas sample from the natural gas inlet;

[0016] (3) Close the metal high vacuum valve II, open the metal high vacuum valve III, wait for 10 seconds, and then close the metal high vacuum valve III;

[0017] (4) heating the tubular electric furnace to 830° C.;

[0018] (5) Place the activated carbon cold finger I in liquid nitrogen, wait for 1 minute, and then place the activated carbon cold finger I at room temperature; place the activated carbon cold finger II in liquid nitrogen, wait for 1 minute, and then place the activated carbon cold finger II at room temperature; repeat this step 3 to 6 times;

[0019] (6) Cooling the tubular electric furnace to 600° C.;

[0020] ⑺Open the metal high vacuum valve IV, introduce the gas sample into the rare gas mass spectrometer system, purify, separate and measure the isotopic composition of each rare gas.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. In view of the characteristics of natural gas, the present invention oxidizes hydrocarbon gas in natural gas into non-hydrocarbon gas through oxidation reaction, making subsequent purification and separation simpler and easier, and the obtained rare gas is purer, so that the detection result is more accurate and reliable.

[0023] 2. The present invention adopts a cyclic oxidation method to repeatedly pass natural gas through high-temperature copper oxide, in order to accelerate the chemical reaction and make the reaction more complete and the oxidation effect better.

[0024] 3. The present invention quantitatively injects natural gas samples, thereby being able to determine the content of rare gases using a mass spectrometry peak height ratio method.

[0025] 4. The present invention can meet the need for preparing more noble gas isotope samples, thereby reducing the requirement for the detection sensitivity of the noble gas isotope mass spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] In the figure: 1—high vacuum system; 2—tubular electric furnace; 3—rare gas mass spectrometer system; 4—pipeline I; 5—pipeline II; 6—natural gas inlet; 7—metal high vacuum valve I; 8—metal high vacuum valve II; 9—metal high vacuum valve III; 10—metal quartz conversion joint I; 11—activated carbon cold finger I; 12—pipeline III; 13—metal quartz conversion joint II; 14—metal high vacuum valve IV; 15—activated carbon cold finger II. DETAILED DESCRIPTION

[0029] like Figure 1As shown, a device for preparing rare gas samples by oxidation of natural gas comprises a high vacuum system 1, a tubular electric furnace 2 and a rare gas mass spectrometer system 3. The high vacuum system 1 is connected to a pipeline II5 via a pipeline I4, one end of the pipeline II5 is connected to a natural gas inlet 6, and the other end thereof passes through the tubular electric furnace 2 and is connected to a pipeline III12; a metal high vacuum valve I7 is provided on the pipeline I4; a metal high vacuum valve II8, a metal high vacuum valve III9, a metal quartz conversion joint I10, and an activated carbon cold finger I11 are respectively provided on the pipeline II5; the end of the pipeline III12 is connected to the rare gas mass spectrometer system 3; a metal quartz conversion joint II13, a metal high vacuum valve IV14, and an activated carbon cold finger II15 are respectively provided on the pipeline III12.

[0030] Wherein: an activated carbon cold finger Ⅰ11 is provided on the pipeline Ⅱ5 between the metal high vacuum valve Ⅲ9 and the metal quartz conversion joint Ⅰ10.

[0031] A pipeline Ⅰ4 is provided on the pipeline Ⅱ5 between the metal high vacuum valve Ⅱ8 and the metal high vacuum valve Ⅲ9.

[0032] Asbestos baffles are provided at both ends of the tubular electric furnace 2, and the temperature thereof is controlled to be 400-900°C.

[0033] An activated carbon cold finger II15 is provided on the pipeline III12 between the metal quartz conversion joint II13 and the metal high vacuum valve IV14.

[0034] The pipeline II5 between the metal quartz conversion joint I10 and the natural gas inlet 6 and the pipeline III12 between the metal quartz conversion joint II13 and the rare gas mass spectrometer system 3 are both metal pipelines.

[0035] The pipeline II5 and the pipeline III12 between the metal quartz conversion joint I10 and the metal quartz conversion joint II13 are both quartz pipelines, and the quartz pipelines are filled with linear copper oxide.

[0036] The method for using the device for preparing rare gas samples by oxidizing natural gas comprises the following steps:

[0037] ⑴ Close the metal high vacuum valve IV14, open the metal high vacuum valve I7, metal high vacuum valve II8, and metal high vacuum valve III9, and evacuate the high vacuum system 1; at the same time, heat the tubular electric furnace 2 to 400°C.

[0038] (2) Close the metal high vacuum valve I7, close the metal high vacuum valve III9, and quantitatively inject the natural gas sample from the natural gas inlet 6. The natural gas sample is quantitatively injected, so that the content of the rare gas can be determined by the mass spectrometry peak height ratio method.

[0039] ⑶ Close the metal high vacuum valve Ⅱ8, open the metal high vacuum valve Ⅲ9, wait for 10 seconds, and then close the metal high vacuum valve Ⅲ9.

[0040] (4) The temperature of the tubular electric furnace 2 is raised to 830°C to oxidize the natural gas, converting the hydrocarbons in the natural gas into carbon dioxide and water, making the next step of purification easier and more effective.

[0041] ⑸ Place the activated carbon cold finger I11 in liquid nitrogen, wait for 1 minute, and then place the activated carbon cold finger I11 at room temperature; place the activated carbon cold finger II15 in liquid nitrogen, wait for 1 minute, and then place the activated carbon cold finger II15 at room temperature; repeat this step 3 to 6 times; make the natural gas repeatedly pass through the high-temperature copper oxide, and the oxidation effect is better.

[0042] (6) Cool the tubular electric furnace 2 to 600°C to absorb excess oxygen produced by the decomposition of copper oxide.

[0043] ⑺Open the metal high vacuum valve IV14, introduce the gas sample into the rare gas mass spectrometer system 3, purify, separate and measure the isotopic composition of each rare gas.

[0044] Example 1 The measurement of xenon isotope composition of a natural gas sample is taken as an example for description.

[0045] A method for using a device for preparing a rare gas sample by oxidizing natural gas comprises the following steps:

[0046] ⑴ Close the metal high vacuum valve IV14, open the metal high vacuum valve I7, metal high vacuum valve II8, and metal high vacuum valve III9, and evacuate the high vacuum system 1; at the same time, heat the tubular electric furnace 2 to 400°C.

[0047] ⑵ Close the metal high vacuum valve Ⅰ7, close the metal high vacuum valve Ⅲ9, and inject A = 2mL of natural gas sample from the natural gas inlet 6.

[0048] ⑶ Close the metal high vacuum valve Ⅱ8, open the metal high vacuum valve Ⅲ9, wait for 10 seconds, and then close the metal high vacuum valve Ⅲ9.

[0049] (4) Heat the tubular electric furnace 2 to 830°C.

[0050] ⑸ Place the activated carbon cold finger I11 in liquid nitrogen, wait for 1 min, and then place the activated carbon cold finger I11 at room temperature; place the activated carbon cold finger II15 in liquid nitrogen, wait for 1 min, and then place the activated carbon cold finger II15 at room temperature; repeat this step 3 times.

[0051] (6) Cool down the tubular electric furnace 2 to 600°C.

[0052] ⑺Open the metal high vacuum valve IV14, and introduce the gas sample into the rare gas mass spectrometer system 3. In the purification device of the rare gas mass spectrometer system 3: use a -60°C cold trap to remove water, use a zirconium aluminum pump to remove active gases such as carbon dioxide, and use a liquid nitrogen cold trap to separate xenon from pure rare gas. Use a mass spectrometer to measure the isotopic composition of xenon.

[0053] At the same time, the xenon isotope composition is measured using air as the reference gas. 0 = 0.2mL air sample, the rest of the steps are the same.

[0054] Measured natural gas samples 132 The mass spectrum peak height of Xe is I = 26391 counts / second, and the air sample is measured 132 The mass spectrum peak height of Xe is I 0 = 45391 counts / second. Take air sample 132 The generally accepted value of Xe content is S = 2.34×10 -8 (V / V), the natural gas sample is calculated by comparison method 132 Xe content is:

[0055] C( 132 Xe) = (I / A) / (I 0 / A 0 )×S

[0056] = (26391 / 2) / (45391 / 0.2)×2.34×10 -8

[0057] = 1.36 × 10 -9 (V / V)

[0058] Other xenon isotopes ( 124 Xe, 126 Xe, 128 Xe, 129 Xe, 130 Xe, 131 Xe, 134 Xe and 136 The content of Xe can be calculated in the same way.

Claims

1. A device for preparing rare gas samples by oxidizing natural gas, characterized in that: The device comprises a high vacuum system (1), a tubular electric furnace (2) and a rare gas mass spectrometer system (3); the high vacuum system (1) is connected to a pipeline II (5) via a pipeline I (4); one end of the pipeline II (5) is connected to a natural gas inlet (6), and the other end thereof passes through the tubular electric furnace (2) and is connected to a pipeline III (12); a metal high vacuum valve I (7) is provided on the pipeline I (4); a metal high vacuum valve II (8), a metal high vacuum valve III (9), a metal quartz conversion joint I (10), and an activated carbon cold finger I (11) are respectively provided on the pipeline II (5); the pipeline III ( The end of the pipeline Ⅲ (12) is connected to the rare gas mass spectrometer system (3); the pipeline Ⅲ (12) is respectively provided with a metal quartz conversion joint Ⅱ (13), a metal high vacuum valve Ⅳ (14), and an activated carbon cold finger Ⅱ (15); asbestos baffles are provided at both ends of the tubular electric furnace (2), and the temperature thereof is controlled to be 400-900°C; the pipeline Ⅱ (5) and the pipeline Ⅲ (12) between the metal quartz conversion joint Ⅰ (10) and the metal quartz conversion joint Ⅱ (13) are both quartz pipelines, and the quartz pipelines are filled with linear copper oxide; the method for using the device comprises the following steps: (1) Close the metal high vacuum valve IV (14), open the metal high vacuum valve I (7), metal high vacuum valve II (8), and metal high vacuum valve III (9), and evacuate the high vacuum system (1); at the same time, heat the tubular electric furnace (2) to 400°C; (2) closing the metal high vacuum valve I (7), closing the metal high vacuum valve III (9), and quantitatively injecting a natural gas sample from the natural gas inlet (6); (3) Close the metal high vacuum valve II (8), open the metal high vacuum valve III (9), wait for 10 seconds, and then close the metal high vacuum valve III (9); (4) raising the temperature of the tubular electric furnace (2) to 830° C.; (5) Place the activated carbon cold finger I (11) in liquid nitrogen, wait for 1 minute, and then place the activated carbon cold finger I (11) at room temperature; place the activated carbon cold finger II (15) in liquid nitrogen, wait for 1 minute, and then place the activated carbon cold finger II (15) at room temperature; repeat this step 3 to 6 times; (6) Cooling the tubular electric furnace (2) to 600° C.; ⑺Open the metal high vacuum valve IV (14) and introduce the gas sample into the noble gas mass spectrometer system (3) to purify, separate and measure the isotopic composition of each noble gas.

2. The device for preparing rare gas samples by oxidation of natural gas as claimed in claim 1, characterized in that: The activated carbon cold finger I (11) is provided on the pipeline II (5) between the metal high vacuum valve III (9) and the metal quartz conversion joint I (10).

3. The device for preparing rare gas samples by oxidizing natural gas according to claim 1, characterized in that: The pipeline I (4) is provided on the pipeline II (5) between the metal high vacuum valve II (8) and the metal high vacuum valve III (9).

4. The device for preparing rare gas samples by oxidizing natural gas according to claim 1, characterized in that: The activated carbon cold finger II (15) is provided on the pipeline III (12) between the metal quartz conversion joint II (13) and the metal high vacuum valve IV (14).

5. The device for preparing rare gas samples by oxidizing natural gas according to claim 1, characterized in that: The pipeline II (5) between the metal quartz conversion joint I (10) and the natural gas inlet (6), and the pipeline III (12) between the metal quartz conversion joint II (13) and the rare gas mass spectrometer system (3) are both metal pipelines.

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