A fully automatic online carbon monoxide gas carbon and oxygen isotope detection device and method thereof

Abstract

The application provides a kind of full-automatic online carbon monoxide gas carbon and oxygen isotope detection device and method thereof, including sampling assembly, purification assembly, carrier gas supply assembly, separation assembly.The sample disc of sampling assembly, autosampler, concentric needle are used for the automatic sampling of carbon monoxide;The drying tube, liquid nitrogen cold trap, automatic lifting mechanism of purification assembly are used to exclude CO2 and water molecules;The total pressure gauge, four three-way valves, flow limiting valve, four different peek tubes of carrier gas supply assembly are used for the supply of He in gas circuit and the control of system pressure and flow rate;8-way valve, 4-way valve and 5A molecular sieve chromatographic column of separation assembly are used for separating carbon monoxide and nitrogen, and nitrogen is evacuated, and isotopic mass spectrometer is used for detecting the carbon and oxygen isotope of CO gas after separation and purification.The application utilizes low-temperature cold trap and Nafion drying tube, switches the purified gas through two groups of multi-pass gas circuit valves, realizes the detection of carbon and oxygen isotope of CO gas.

Description

Technical Field

[0001] This application belongs to the field of gas stable isotope analysis technology, and in particular relates to a fully automated online carbon monoxide gas carbon and oxygen isotope detection device and method. Background Technology

[0002] CO is a product of the incomplete combustion of carbonaceous materials such as coal and oil, and is an air pollutant. The CO concentration in the troposphere is approximately 0.1–2 ppm, a concentration harmless to humans. However, abnormal CO concentrations in some coal mines pose a risk of spontaneous combustion. Yet, some studies have found that high CO concentrations have not caused spontaneous combustion in coal. Some believe that CO is a type of coalbed methane, meaning that the coal seam contains native CO gas, rather than being produced by the oxidation of exposed coal. However, this view has not yet been effectively proven, and whether CO can serve as an indicator of spontaneous combustion in coal is highly controversial. Therefore, accurately studying the occurrence and emission patterns of native CO in coal seams is essential for safe coal mine production. Testing CO carbon and oxygen isotopes can help determine the origin of CO and analyze its occurrence patterns, exploring new methods for predicting spontaneous combustion in coal, which is of great significance for safe and efficient coal mine production.

[0003] Currently, CO carbon and oxygen isotopes are detected using gas chromatography-stable isotope mass spectrometry (GC-MS). However, GC-MS CO carbon and oxygen isotope detection requires manual sample injection, which is slow, time-consuming, and labor-intensive. Moreover, the CO content in the sample is relatively low compared to N2, requiring a large sample volume for CO detection. Before detection, it is necessary not only to eliminate CO2 interference but also, especially, N2 interference. Before the gas enters the gas stable isotope mass spectrometer, the separated N2 must be purged and not allowed to enter the mass spectrometer. Otherwise, some samples with high N2 content will exceed the detection limit of the mass spectrometer, making it impossible to obtain accurate detection results. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a fully automatic online carbon monoxide gas carbon and oxygen isotope detection device and method that automatically introduces samples, performs continuous online testing, and improves testing efficiency and accuracy.

[0005] The first aspect of this application provides a fully automated online carbon monoxide gas carbon and oxygen isotope detection device, including a sample introduction component, a purification component, a separation component and an isotope mass spectrometer connected in sequence by pipelines, and a carrier gas supply component connected to the sample introduction component, the purification component and the separation component respectively.

[0006] In any embodiment, the sample introduction assembly includes a concentric needle, a headspace vial, a through-plate tee, a PEek purge tube, a sample tray, and an autosampler. The concentric needle is connected to the upper and lower parts of the through-plate tee and inserted into the headspace vial. The PEek purge tube is connected to the side of the through-plate tee and communicates with the concentric needle. The PEek purge tube is connected to a carrier gas supply assembly. The assembled headspace vial is placed on the sample tray. The autosampler is positioned above the sample tray, inserted into the through-plate tee, and connected to the concentric needle. The autosampler is connected to a purification assembly.

[0007] In any embodiment, the concentric needle comprises a short needle and a long needle. The long needle is nested inside the short needle. The short needle is a stainless steel tube with an inner diameter of 1 mm and an outer diameter of 1.6 mm. The short needle is the outer needle and is connected to the lower part of the through-plate tee. The PEek purge tube has an inner diameter of 0.5 mm and an outer diameter of 1.6 mm and is connected to the outer needle. The long needle has a side opening with an inner diameter of 0.5 mm and an outer diameter of 0.9 mm. A stainless steel injection tube with an outer diameter of 0.45 mm and an inner diameter of 0.3 mm is embedded inside the long needle. The stainless steel injection tube is sealed to the side opening of the long needle. The upper end of the stainless steel injection tube is connected to the purification assembly via an autosampler.

[0008] In any embodiment, the purification assembly includes a first drying tube, a liquid nitrogen cold trap, and an automatic lifting mechanism. One end of the first drying tube is connected to a stainless steel injection tube via an automatic sampler, and the other end is connected to the liquid nitrogen cold trap. The automatic lifting mechanism is connected to the liquid nitrogen cold trap.

[0009] In any embodiment, the liquid nitrogen cold trap is provided with a quartz capillary column with an inner diameter of 0.32 mm embedded in a stainless steel tube with an inner diameter of 0.75 mm and a liquid nitrogen tank. The automatic lifting mechanism is provided with a five-position three-way air valve and a cylinder. The cylinder is connected to the stainless steel tube, and the cylinder is extended and retracted by the five-position three-way air valve to drive the stainless steel tube in and out of the liquid nitrogen tank.

[0010] In any embodiment, the carrier gas supply assembly includes a total pressure gauge, a three-way valve, a flow restrictor valve, and a PEek gas supply pipe. The three-way valve includes a first three-way valve, a second three-way valve, a third three-way valve, a fourth three-way valve, and a fifth three-way valve. The first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve are connected sequentially via pipes. The fifth three-way valve is connected to the side interface of the second three-way valve. The PEek gas supply pipe includes a first gas supply pipe, a second gas supply pipe, a third gas supply pipe, a fourth gas supply pipe, a fifth gas supply pipe, and a sixth gas supply pipe. The first gas supply pipe is connected to the first three-way valve. The second gas supply pipe and the third gas supply pipe are respectively connected to the fifth three-way valve. The third and fourth gas supply pipes are connected to the third three-way valve. The fifth and sixth gas supply pipes are connected to the fourth three-way valve. The total pressure gauge and the flow restrictor valve are located on the pipe upstream of the first three-way valve.

[0011] In any embodiment, the first air supply pipe has an inner diameter of 0.5 mm and a length of 1 m; the second and third air supply pipes have an inner diameter of 0.1 mm and a length of 2 m; the fourth air supply pipe has an inner diameter of 0.12 mm and a length of 3 m; and the fifth and sixth air supply pipes have an inner diameter of 0.12 mm and a length of 2 m.

[0012] In any embodiment, the separation assembly includes an eight-way valve, a metering loop, a four-way valve, and a 5A molecular sieve column. Port 1 of the eight-way valve is connected to a liquid nitrogen cold trap. Both ends of the metering loop are connected to ports 2 and 5 of the eight-way valve. The 5A molecular sieve column is connected to port 3 of the eight-way valve. Port 4 of the eight-way valve is connected to a first gas supply pipe, and port 7 of the eight-way valve is connected to a third gas supply pipe. The other end of the 5A molecular sieve column is connected to port 1 of the four-way valve. Port 2 of the four-way valve is connected to an isotope mass spectrometer, and port 3 of the four-way valve is connected to a fourth gas supply pipe. A second drying tube is provided between the four-way valve and the isotope mass spectrometer. The purge gas inlets of the first and second drying tubes are connected to the fifth and sixth gas supply pipes, respectively. The PEek purge tube is connected to the second gas supply pipe.

[0013] In any embodiment, the pressure value of the total pressure gauge is 15 PSI.

[0014] A second aspect of this application also provides a fully automated online method for detecting carbon and oxygen isotopes in carbon monoxide gas, comprising the following steps:

[0015] 1) Collect the sample gas into a glass headspace vial and place it in a sample tray. Purge the carrier gas He into the headspace vial through a concentric needle. Use the carrier gas He to purge the sample gas containing carbon monoxide out of the headspace vial. The H2O and CO2 components in the sample gas are removed by passing through the first drying tube of the purification assembly and the liquid nitrogen cold trap.

[0016] 2) The purified gas enters the metering loop along with the carrier gas He;

[0017] 3) After the quantitative loop is filled, switch the 8-way valve to connect the quantitative loop to the 5A molecular sieve column to separate carbon monoxide and nitrogen.

[0018] 4) The nitrogen gas separated by the 5A molecular sieve column is vented through a 4-way valve;

[0019] 5) After the nitrogen gas has been completely discharged from the chromatographic column, switch the 4-way valve to connect the chromatographic column to the isotope mass spectrometer. Carbon monoxide gas enters the isotope mass spectrometer to detect carbon and oxygen isotopes.

[0020] In any embodiment, the purge carrier gas He flow rate in step 1) is 0.5~1.2 mL / min.

[0021] In any embodiment, the time for filling the quantitative loop in step 2) is 120s.

[0022] In any embodiment, the column oven temperature in step 3) is 30°C.

[0023] In any embodiment, the nitrogen venting flow rate in step 4) is 1~2 mL / min.

[0024] In any embodiment, the concentric needle comprises a short needle and a long needle. The long needle is nested inside the short needle. The short needle is a stainless steel tube with an inner diameter of 1 mm and an outer diameter of 1.6 mm. The short needle is the outer needle and is connected to the lower part of the through-plate tee. The PEek purge tube has an inner diameter of 0.5 mm and an outer diameter of 1.6 mm and is connected to the outer needle. The long needle has a side opening with an inner diameter of 0.5 mm and an outer diameter of 0.9 mm. A stainless steel injection tube with an outer diameter of 0.45 mm and an inner diameter of 0.3 mm is embedded inside the long needle. The stainless steel injection tube is sealed to the side opening of the long needle. The upper end of the stainless steel injection tube is connected to the purification assembly via an autosampler.

[0025] In any embodiment, the liquid nitrogen cold trap is provided with a quartz capillary column with an inner diameter of 0.32 mm embedded in a stainless steel tube with an inner diameter of 0.75 mm and a liquid nitrogen tank. The automatic lifting mechanism is provided with a five-position three-way air valve and a cylinder. The cylinder is connected to the stainless steel tube, and the cylinder is extended and retracted by the five-position three-way air valve to drive the stainless steel tube in and out of the liquid nitrogen tank.

[0026] In any embodiment, the carrier gas supply assembly includes a total pressure gauge, a three-way valve, a flow restrictor valve, and a PEek gas supply pipe. The three-way valve includes a first three-way valve, a second three-way valve, a third three-way valve, a fourth three-way valve, and a fifth three-way valve. The first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve are connected sequentially via pipes. The fifth three-way valve is connected to the side interface of the second three-way valve. The PEek gas supply pipe includes a first gas supply pipe, a second gas supply pipe, a third gas supply pipe, a fourth gas supply pipe, a fifth gas supply pipe, and a sixth gas supply pipe. The first gas supply pipe is connected to the first three-way valve. The second gas supply pipe and the third gas supply pipe are respectively connected to the fifth three-way valve. The third and fourth gas supply pipes are connected to the third three-way valve. The fifth and sixth gas supply pipes are connected to the fourth three-way valve. The total pressure gauge and the flow restrictor valve are located on the pipe upstream of the first three-way valve.

[0027] In any embodiment, the first air supply pipe has an inner diameter of 0.5 mm and a length of 1 m; the second and third air supply pipes have an inner diameter of 0.1 mm and a length of 2 m; the fourth air supply pipe has an inner diameter of 0.12 mm and a length of 3 m; and the fifth and sixth air supply pipes have an inner diameter of 0.12 mm and a length of 2 m.

[0028] In any embodiment, the separation assembly includes an eight-way valve, a metering loop, a four-way valve, and a 5A molecular sieve column. Port 1 of the eight-way valve is connected to a liquid nitrogen cold trap. Both ends of the metering loop are connected to ports 2 and 5 of the eight-way valve. The 5A molecular sieve column is connected to port 3 of the eight-way valve. Port 4 of the eight-way valve is connected to a first gas supply pipe, and port 7 of the eight-way valve is connected to a third gas supply pipe. The other end of the 5A molecular sieve column is connected to port 1 of the four-way valve. Port 2 of the four-way valve is connected to an isotope mass spectrometer, and port 3 of the four-way valve is connected to a fourth gas supply pipe. A second drying tube is provided between the four-way valve and the isotope mass spectrometer. The purge gas inlets of the first and second drying tubes are connected to the fifth and sixth gas supply pipes, respectively. The PEek purge tube is connected to the second gas supply pipe.

[0029] In any implementation, the pressure and flow rate of the peek purge tube and port 7 of the eight-way valve must be consistent.

[0030] In any embodiment, the pressure value of the total pressure gauge is 15 PSI.

[0031] The beneficial effects of this application are as follows: This application uses Nafion drying tubes and a cryogenic liquid nitrogen cold trap to purify the sample gas, eliminating the influence of CO2 and nitrogen on the test results. Nitrogen is separated by a 5A molecular sieve column, and the purified gas is switched through two sets of multi-channel gas path valves to achieve the detection of carbon and oxygen isotopes of CO gas. The device integrates an automatic gas purging and injection component, a gas purification component, a carrier gas supply and pressure distribution system, and a carbon monoxide and nitrogen chromatographic column separation component, realizing automatic injection and online continuous testing, improving testing efficiency and accuracy. This application utilizes a GasBench-IRMS (Gas Stable Isotope Mass Spectrometer) to test CO standard gas. The results show good linearity between peak area and concentration in the range of 300–16000 ppm, with a correlation coefficient (r²) of 0.9992. When the CO standard gas concentration is between 800 and 20000 ppm, the standard deviation of its carbon and oxygen isotopes is within 1.0‰. For testing 1000 ppm CO standard gas, the standard deviation of repeated measurements is within 0.5‰. The precision of carbon and oxygen isotope testing of CO from coalbed methane products is less than 0.5‰, meeting the testing requirements. This device has a simple structure, high degree of automation, and low detection limit. The relative standard deviation of its oxygen isotope test results meets the testing requirements. It is particularly suitable for the detection of carbon and oxygen isotopes in CO from coal reaction gas, providing excellent precision. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a fully automated online carbon monoxide gas carbon and oxygen isotope detection device.

[0033] Figure 2 This is a schematic diagram of the sample introduction component of a fully automated online carbon monoxide gas carbon and oxygen isotope detection device.

[0034] Figure 3 This is a schematic diagram of the impurity removal process in a fully automated online carbon and oxygen isotope detection method for carbon monoxide gas.

[0035] Figure 4 This is a schematic diagram illustrating the separation process in a fully automated online carbon monoxide gas carbon and oxygen isotope detection method.

[0036] Figure 5 This is a schematic diagram of isotope determination in a fully automated online carbon monoxide gas carbon and oxygen isotope detection method.

[0037] Figure 6 yes Figure 5 The CO spectrum shown is from one embodiment of this application. (a: CO spectrum without N2 removal; b: CO spectrum after N2 removal)

[0038] Figure 7 This is a linear relationship graph between the CO standard gas concentration and peak area according to an embodiment of this application.

[0039] Figure 8 This is a graph showing the carbon isotope test results of CO standard gas at concentrations of 300~2000ppm according to one embodiment of this application.

[0040] Figure 9 This is a graph showing the oxygen isotope test results of CO standard gas at concentrations ranging from 300 to 2000 ppm.

[0041] Explanation of reference numerals in the attached figures:

[0042] Sample introduction assembly 1; concentric needle 11; short needle 111; long needle 112; side opening 113; stainless steel sample introduction tube 114; headspace vial 12; through-plate tee 13; PEEK purge tube 14; purification assembly 2; first drying tube 21; liquid nitrogen cold trap 22; separation assembly 3; eight-way valve 31; quantitative loop 32; four-way valve 33; 5A molecular sieve column 34; isotope mass spectrometer 4; second drying tube 41; carrier gas supply assembly 5; total pressure gauge 51; three-way valve 52; first three-way valve 521; second three-way valve 522; third three-way valve 523; fourth three-way valve 524; fifth three-way valve 525; flow limiting valve 53; PEEK gas supply tube 54; first gas supply tube 541; second gas supply tube 542; third gas supply tube 543; fourth gas supply tube 544; fifth gas supply tube 545; sixth gas supply tube 546. Detailed Implementation

[0043] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the online carbon monoxide gas carbon and oxygen isotope detection device and method of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0044] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0046] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0047] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0048] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0049] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0050] refer to Figure 1-5 As shown, an online carbon monoxide gas carbon and oxygen isotope detection device includes a sample introduction component 1, a purification component 2, a separation component 3 and an isotope mass spectrometer 4 connected in sequence by pipelines, and a carrier gas supply component 5 connected to the sample introduction component 1, the purification component 2 and the separation component 3 respectively.

[0051] In some embodiments, the sample introduction assembly 1 includes a concentric needle 11, a headspace vial 12, a through-plate tee 13, a PEek purge tube 14, a sample tray, and an autosampler. The concentric needle 11 is connected to the upper and lower parts of the through-plate tee 13 and inserted into the headspace vial 12. The PEek purge tube 14 is connected to the side of the through-plate tee 13 and communicates with the concentric needle 11. The PEek purge tube 14 is connected to the carrier gas supply assembly 5. The assembled headspace vial 12 is placed on the sample tray. The autosampler is positioned above the sample tray, inserted into the through-plate tee 13, and connected to the concentric needle 11. The autosampler is connected to the purification assembly 2.

[0052] In some embodiments, the concentric needle 11 is provided with a short needle 111 and a long needle 112. The long needle 112 is nested inside the short needle 111. The short needle 111 is a stainless steel tube with an inner diameter of 1 mm and an outer diameter of 1.6 mm. The short needle 111 is the outer needle and is connected to the lower part of the through-plate tee 13. The PEek purge tube 14 has an inner diameter of 0.5 mm and an outer diameter of 1.6 mm and is connected to the outer needle. The long needle 112 is a side opening 113. The long needle 112 has an inner diameter of 0.5 mm and an outer diameter of 0.9 mm. A stainless steel injection tube 114 with an outer diameter of 0.45 mm and an inner diameter of 0.3 mm is embedded inside the long needle 112. The stainless steel injection tube 114 is sealed to the side opening 113 of the long needle 112. The upper end of the stainless steel injection tube 114 is connected to the purification assembly 2 through an autosampler.

[0053] In some embodiments, the purification assembly 2 is provided with a first drying tube 21, a liquid nitrogen cold trap 22 and an automatic lifting mechanism. One end of the first drying tube 21 is connected to a stainless steel injection tube 114 via an automatic sampler, and the other end is connected to the liquid nitrogen cold trap 22. The automatic lifting mechanism is connected to the liquid nitrogen cold trap 22.

[0054] In some embodiments, the liquid nitrogen cold trap 22 is provided with a quartz capillary column with an inner diameter of 0.32 mm embedded in a stainless steel tube with an inner diameter of 0.75 mm and a liquid nitrogen tank. The automatic lifting mechanism is provided with a five-position three-way air valve and a cylinder. The cylinder is connected to the stainless steel tube, and the cylinder is extended and retracted by the five-position three-way air valve to drive the stainless steel tube in and out of the liquid nitrogen tank.

[0055] In some embodiments, the carrier gas supply assembly 5 includes a total pressure gauge 51, a three-way valve 52, a flow restrictor valve 53, and a PEEK supply pipe 54. The three-way valve 52 includes a first three-way valve 521, a second three-way valve 522, a third three-way valve 523, a fourth three-way valve 524, and a fifth three-way valve 525. The first three-way valve 521, the second three-way valve 522, the third three-way valve 523, and the fourth three-way valve 524 are connected sequentially via pipes, and the fifth three-way valve 525 is connected to the side interface of the second three-way valve 522. The PEEK supply pipe 54 includes a first supply... The system includes an air supply pipe 541, a second air supply pipe 542, a third air supply pipe 543, a fourth air supply pipe 544, a fifth air supply pipe 545, and a sixth air supply pipe 546. The first air supply pipe 541 is connected to a first three-way valve 521. The second air supply pipe 542 and the third air supply pipe 543 are respectively connected to a fifth three-way valve 525. The third and fourth air supply pipes 544 are connected to a third three-way valve 523. The fifth air supply pipe 545 and the sixth air supply pipe 546 are connected to a fourth three-way valve 524. The total pressure gauge 51 and the flow limiting valve 53 are located on the pipe upstream of the first three-way valve 521.

[0056] In some embodiments, the first air supply pipe 541 has an inner diameter of 0.5 mm and a length of 1 m; the second air supply pipe 542 and the third air supply pipe 543 have an inner diameter of 0.1 mm and a length of 2 m; the fourth air supply pipe 544 has an inner diameter of 0.12 mm and a length of 3 m; and the fifth air supply pipe 545 and the sixth air supply pipe 546 have an inner diameter of 0.12 mm and a length of 2 m.

[0057] The total pressure gauge 51 is adjusted to 15 PSI. The flow rate and pressure of He in each passage are controlled by the flow limiting valve 53 and the PEK air supply pipes 54 with different inner diameters and lengths to ensure pressure balance when switching air paths.

[0058] In some embodiments, the separation component 3 includes an eight-way valve 31, a metering loop 32, a four-way valve 33, and a 5A molecular sieve column 34. Port 1 of the eight-way valve is connected to a liquid nitrogen cold trap 22. Both ends of the metering loop 32 are connected to ports 2 and 5 of the eight-way valve. The 5A molecular sieve column 34 is connected to port 3 of the eight-way valve. Port 4 of the eight-way valve is connected to a first gas supply pipe 541, and port 7 of the eight-way valve is connected to a third gas supply pipe 543. The 5A molecular sieve column 34... The other end of the sub-sieve chromatographic column 34 is connected to port 1 of the four-way valve, port 2 of the four-way valve is connected to the isotope mass spectrometer 4, and port 3 of the four-way valve is connected to the fourth gas supply pipe 544; a second drying pipe 41 is provided between the four-way valve 33 and the isotope mass spectrometer 4, and the purge gas inlets of the first drying pipe 21 and the second drying pipe 41 are respectively connected to the fifth gas supply pipe 545 and the sixth gas supply pipe 546, and the PEek purge pipe 14 is connected to the second gas supply pipe 542.

[0059] The first drying tube 21 and the second drying tube 41 are Nafion gas drying tubes. The isotope mass spectrometer 4 is a stable isotope ratio mass spectrometer.

[0060] In some embodiments, the pressure value of the total pressure gauge 51 is 15 PSI.

[0061] A second aspect of this application also provides an online method for detecting carbon and oxygen isotopes in carbon monoxide gas, comprising the following steps:

[0062] 1) Collect the sample gas into the glass headspace vial 12 and place it in the sample tray. Purge the carrier gas He into the headspace vial 12 through the concentric needle 11. Use the carrier gas He to purge the sample gas containing carbon monoxide out of the headspace vial 12. Remove the H2O and CO2 components from the sample gas through the first drying tube 21 and liquid nitrogen cold trap 22 of the purification component 2.

[0063] 2) The purified gas enters the metering loop 32 along with the carrier gas He;

[0064] 3) After the quantitative loop 32 is filled, switch the 8-way valve to connect the quantitative loop 32 to the 5A molecular sieve column 34 to separate carbon monoxide and nitrogen.

[0065] 4) The nitrogen gas separated by the 5A molecular sieve column 34 is vented through a 4-way valve;

[0066] 5) After the nitrogen gas has been completely discharged from the chromatographic column, switch the 4-way valve to connect the chromatographic column to the isotope mass spectrometer. Carbon monoxide gas enters the isotope mass spectrometer 4 to detect carbon and oxygen isotopes.

[0067] In steps 1) and 2), port 1 of the eight-way valve 31 is connected to port 2, port 3 is connected to port 4, port 5 is connected to port 6, port 7 is connected to port 8, and ports 6 and 8 are vent outlets; port 1 of the four-way valve 33 is connected to port 4, port 2 is connected to port 3, and port 4 is a vent outlet.

[0068] In steps 3) and 4), port 1 of the eight-way valve 31 is connected to port 8, port 2 is connected to port 3, port 4 is connected to port 5, port 6 is connected to port 7, and ports 6 and 8 are vent outlets; port 1 of the four-way valve 33 is connected to port 4, port 2 is connected to port 3, and port 4 is a vent outlet.

[0069] In step 5), port 1 of the eight-way valve 31 is connected to port 8, port 2 is connected to port 3, port 4 is connected to port 5, port 6 is connected to port 7, and ports 6 and 8 are vent outlets; port 1 of the four-way valve 33 is connected to port 2, port 3 is connected to port 4, and port 4 is a vent outlet.

[0070] In some embodiments, the purge carrier gas He flow rate in step 1) is 0.5~1.2 mL / min. A preferred flow rate is 1.0 mL / min. A flow rate that is too high will dilute the sample and affect the detection limit.

[0071] In some embodiments, the time for filling the quantitative ring 32 in step 2) is 120s.

[0072] In some embodiments, the column oven temperature in step 3) is 30°C.

[0073] In some embodiments, the nitrogen purging flow rate in step 4) is 1-2 mL / min. A preferred nitrogen purging flow rate is 1.8 mL / min. A higher flow rate results in a higher dilution factor and a lower detection limit.

[0074] In some embodiments, the concentric needle 11 is provided with a short needle 111 and a long needle 112. The long needle 112 is nested inside the short needle 111. The short needle 111 is a stainless steel tube with an inner diameter of 1 mm and an outer diameter of 1.6 mm. The short needle 111 is the outer needle and is connected to the lower part of the through-plate tee 13. The PEek purge tube 14 has an inner diameter of 0.5 mm and an outer diameter of 1.6 mm and is connected to the outer needle. The long needle 112 is a side opening 113. The long needle 112 has an inner diameter of 0.5 mm and an outer diameter of 0.9 mm. A stainless steel injection tube 114 with an outer diameter of 0.45 mm and an inner diameter of 0.3 mm is embedded inside the long needle 112. The stainless steel injection tube 114 is sealed to the side opening 113 of the long needle 112. The upper end of the stainless steel injection tube 114 is connected to the purification assembly 2 through an autosampler.

[0075] In some embodiments, the liquid nitrogen cold trap 22 is provided with a quartz capillary column with an inner diameter of 0.32 mm embedded in a stainless steel tube with an inner diameter of 0.75 mm and a liquid nitrogen tank. The automatic lifting mechanism is provided with a five-position three-way air valve and a cylinder. The cylinder is connected to the stainless steel tube, and the cylinder is extended and retracted by the five-position three-way air valve to drive the stainless steel tube in and out of the liquid nitrogen tank.

[0076] In some embodiments, the carrier gas supply assembly 5 includes a total pressure gauge 51, a three-way valve 52, a flow restrictor valve 53, and a PEEK supply pipe 54. The three-way valve 52 includes a first three-way valve 521, a second three-way valve 522, a third three-way valve 523, a fourth three-way valve 524, and a fifth three-way valve 525. The first three-way valve 521, the second three-way valve 522, the third three-way valve 523, and the fourth three-way valve 524 are connected sequentially via pipes, and the fifth three-way valve 525 is connected to the side interface of the second three-way valve 522. The PEEK supply pipe 54 includes a first supply... The system includes an air supply pipe 541, a second air supply pipe 542, a third air supply pipe 543, a fourth air supply pipe 544, a fifth air supply pipe 545, and a sixth air supply pipe 546. The first air supply pipe 541 is connected to a first three-way valve 521. The second air supply pipe 542 and the third air supply pipe 543 are respectively connected to a fifth three-way valve 525. The third and fourth air supply pipes 544 are connected to a third three-way valve 523. The fifth air supply pipe 545 and the sixth air supply pipe 546 are connected to a fourth three-way valve 524. The total pressure gauge 51 and the flow limiting valve 53 are located on the pipe upstream of the first three-way valve 521.

[0077] In some embodiments, the first air supply pipe 541 has an inner diameter of 0.5 mm and a length of 1 m; the second air supply pipe 542 and the third air supply pipe 543 have an inner diameter of 0.1 mm and a length of 2 m; the fourth air supply pipe 544 has an inner diameter of 0.12 mm and a length of 3 m; and the fifth air supply pipe 545 and the sixth air supply pipe 546 have an inner diameter of 0.12 mm and a length of 2 m.

[0078] In some embodiments, the separation component 3 includes an eight-way valve 31, a metering loop 32, a four-way valve 33, and a 5A molecular sieve column 34. Port 1 of the eight-way valve is connected to a liquid nitrogen cold trap 22. Both ends of the metering loop 32 are connected to ports 2 and 5 of the eight-way valve. The 5A molecular sieve column 34 is connected to port 3 of the eight-way valve. Port 4 of the eight-way valve is connected to a first gas supply pipe 541, and port 7 of the eight-way valve is connected to a third gas supply pipe 543. The 5A molecular sieve column 34... The other end of the sub-sieve chromatographic column 34 is connected to port 1 of the four-way valve, port 2 of the four-way valve is connected to the isotope mass spectrometer 4, and port 3 of the four-way valve is connected to the fourth gas supply pipe 544; a second drying pipe 41 is provided between the four-way valve 33 and the isotope mass spectrometer 4, and the purge gas inlets of the first drying pipe 21 and the second drying pipe 41 are respectively connected to the fifth gas supply pipe 545 and the sixth gas supply pipe 546, and the PEek purge pipe 14 is connected to the second gas supply pipe 542.

[0079] The pressure and flow rate requirements of the Peek purge pipe 14 and the 8-way valve port 7 must be consistent.

[0080] In some embodiments, the pressure value of the total pressure gauge 51 is 15 PSI.

[0081] Example

[0082] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0083] An online method for detecting carbon and oxygen isotopes in carbon monoxide gas, specifically comprising:

[0084] 1) Collect the sample into a glass headspace vial, place it in the sample tray, insert the gas purging concentric needle into the headspace vial, and use the carrier gas He to purge the carbon monoxide gas in the sample out of the headspace vial and into the carbon monoxide gas purification component to remove the H2O and CO2 components of the gas.

[0085] 2) The gas passing through the carbon monoxide purification component enters the quantitative loop along with He. The quantitative loop is filled for 120 seconds. Then, the 8-way valve is switched, and the quantitative loop is connected to the 5A molecular sieve column. The column temperature is set to 30°C. The nitrogen gas separated by the column is vented through the venting device of the four-way valve. After the nitrogen gas is completely discharged from the column, about 500 seconds later, the four-way valve is switched, and the column is connected to the mass spectrometer. The carbon monoxide gas enters the isotope mass spectrometer to detect carbon and oxygen isotopes.

[0086] Using the above-described testing apparatus, procedures, and conditions, the following sample experiments were conducted:

[0087] CO oxygen isotope testing procedure and conditions:

[0088] CO gas was purged by a low-flow-rate He gas (approximately 0.5 mL / min), passed through a Nafion tube for water removal, and then through a liquid nitrogen cold trap for CO2 removal before entering the quantitative loop for 120 s. Subsequently, the eight-way valve was switched to injection mode, and the purified sample gas in the quantitative loop was transferred to the column by a low-flow-rate He gas (approximately 2 mL / min). The four-way valve was then switched to allow the sample gas in the quantitative loop to enter the Molesive 5A column (column temperature 30°C), and the four-way valve was switched to connect the Molesive 5A column to the purging line. Based on the nitrogen retention time in the Molesive 5A column, after the nitrogen was completely purged, the four-way valve was switched again (approximately 500 s) to connect the Molesive 5A column to the Nafion tube. After water removal, CO was entered into the gas stable isotope mass spectrometer, and the peaks with mass-to-charge ratios of 28, 29, and 30 were measured, along with their carbon and oxygen isotopes.

[0089] Data processing:

[0090] δ 13 The C value is based on the VPDB international standard, δ 13 The C value is calculated using the following formula:

[0091]

[0092] In the formula, R ( 13 C / 12 C VPDB δ represents the carbon isotope abundance ratio of the international standard VPDB (Vienna Peedee Belemnite). 13 The analytical precision for the C value is ±0.5‰.

[0093] δ 18 O sample The value is used as the VSMOW reference standard, δ 18 O sample The value is calculated using the following formula:

[0094]

[0095] In the formula, R ( 18 O / 16 O VSMOW δ represents the difference in stable oxygen isotope ratio of the sample relative to the stable oxygen isotope ratio of the standard average ocean water. 18 The analytical precision for the O value is ±0.5‰.

[0096] result:

[0097] Gasbench-IRMS CO spectrum

[0098] The mass-to-charge ratios of CO and N2 are both 28, 29, and 30, respectively. The receiving cup of a gas stable isotope mass spectrometer will simultaneously accept ions from both substances. If the sample contains N2, it will significantly affect the test results. Therefore, CO and N2 must be separated using a chromatographic column and detected at different times. The Molesive 5A column can separate nitrogen and CO gases. By setting an appropriate column temperature, nitrogen and CO can be separated, such as... Figure 6 As shown.

[0099] Method detection limit

[0100] CO standard substances of different concentrations were tested on the mass spectrometer from low to high, with each concentration measured in parallel four times. The tests showed that CO concentrations of 100 ppm and 200 ppm were below the instrument's detection limit, and no peaks were detected. Peaks began to be detected on the mass spectrometer at concentrations above 300 ppm. The total peak area of ​​CO on the isotope mass spectrometer was calculated. y, V·s ) and the corresponding volume concentration ( x Plot a linear curve (ppm) (see Figure 7 The results showed a good linear relationship between peak area and concentration in the range of 300–16000 ppm, with a correlation coefficient ( ). r 2) is 0.9992.

[0101] Carbon and oxygen isotope values ​​for different concentrations of CO are shown in the figure. Figure 8 , 9 .from Figure 8 It can be seen that when the CO concentration is below 800 ppm, most δ 13 C、δ 18 The value of O falls outside the line. From Figure 9 It can be seen that the carbon and oxygen isotope values ​​of CO standard gas in the range of 800~16000ppm are basically within the dashed line, indicating that the deviation between the tested carbon and oxygen isotope values ​​and the true values ​​is less than 1‰.

[0102] CO carbon and oxygen isotope precision

[0103] The modified Gas Bench II-IRMS was used to test 1000ppm CO standard gas. The test was randomly repeated 5 times within 6 months, with 4 parallel tests each time. The results are shown in Table 1.

[0104] Table 1. Results of CO standard gas carbon and oxygen isotope tests

[0105]

[0106] The concentration of CO and carbon and oxygen isotope test results of the coalbed methane reaction product at different reaction temperatures are shown in Table 2.

[0107] Table 2. Concentration of CO and carbon and oxygen isotope test results of coalbed methane products.

[0108]

[0109] The results showed that the concentration of CO, a product of coalbed methane reaction, ranged from 1118.46 to 8311.34 ppm at different reaction temperatures. Its carbon isotope values ​​ranged from -20.62 to -26.11‰, with a relative standard deviation of less than 0.5‰, while its oxygen isotope values ​​ranged from 21.3 to 30.1‰, also with a relative standard deviation of less than 0.5‰. Furthermore, as the reaction temperature increased, the concentration of CO gradually increased, and its carbon and oxygen isotope values ​​gradually became lighter, indicating that between 60 and 160℃, the amount of substances participating in the coalbed methane reaction increased, and lighter isotopes were preferentially utilized. This also verifies previous findings on the carbon and oxygen isotope variations of CO products during coal oxidation and the reaction process.

[0110] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A fully automatic online carbon monoxide gas carbon and oxygen isotope detection device, characterized in that, It includes a sample introduction unit, a purification unit, a separation unit and an isotope mass spectrometer connected in sequence by pipelines, and a carrier gas supply unit connected to the sample introduction unit, the purification unit and the separation unit respectively. The carrier gas supply assembly has a first, second, third, fourth, fifth, and sixth air supply pipe. The first air supply pipe has an inner diameter of 0.5 mm and a length of 1 m. The second and third air supply pipes have an inner diameter of 0.1 mm and a length of 2 m. The fourth air supply pipe has an inner diameter of 0.12 mm and a length of 3 m. The fifth and sixth air supply pipes have an inner diameter of 0.12 mm and a length of 2 m. The sample introduction assembly includes a concentric needle, a headspace vial, a through-plate tee, a PEEK purge tube, a sample tray, and an autosampler. The concentric needle is connected to the upper and lower parts of the through-plate tee and inserted into the headspace vial. The PEEK purge tube is connected to the side of the through-plate tee and communicates with the concentric needle. The PEEK purge tube is connected to the carrier gas supply assembly. The assembled headspace vial is placed on the sample tray. The autosampler is positioned above the sample tray, inserted into the through-plate tee, and connected to the concentric needle. The autosampler is connected to the purification assembly. The purification assembly includes a first drying tube, a liquid nitrogen cold trap, and an automatic lifting mechanism. One end of the first drying tube is connected to a concentric needle via an automatic sampler, and the other end is connected to the liquid nitrogen cold trap. The automatic lifting mechanism is connected to the liquid nitrogen cold trap. The separation assembly includes an eight-way valve, a metering loop, a four-way valve, and a 5A molecular sieve column. Port 1 of the eight-way valve is connected to a liquid nitrogen cold trap. Both ends of the metering loop are connected to ports 2 and 5 of the eight-way valve. The 5A molecular sieve column is connected to port 3 of the eight-way valve. Port 4 of the eight-way valve is connected to a first gas supply pipe, and port 7 of the eight-way valve is connected to a third gas supply pipe. The other end of the 5A molecular sieve column is connected to port 1 of the four-way valve. Port 2 of the four-way valve is connected to an isotope mass spectrometer, and port 3 of the four-way valve is connected to a fourth gas supply pipe. A second drying tube is provided between the four-way valve and the isotope mass spectrometer. The purge gas inlets of the first and second drying tubes are connected to the fifth and sixth gas supply pipes, respectively. The PEek purge tube is connected to the second gas supply pipe. The four-way valve is used to selectively vent the separated nitrogen gas before introducing carbon monoxide into the isotope mass spectrometer. The purge carrier gas He flow rate of the sample introduction component is 0.5~1.2 mL / min; the nitrogen purging flow rate of the separation component is 1~2 mL / min.

2. The fully automatic online carbon monoxide gas carbon and oxygen isotope detection device according to claim 1, characterized in that, The carrier gas supply assembly includes a total pressure gauge, a three-way valve, a flow restrictor valve, and a PEEK gas supply pipe. The three-way valve includes a first three-way valve, a second three-way valve, a third three-way valve, a fourth three-way valve, and a fifth three-way valve. The first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve are connected sequentially via pipes. The fifth three-way valve is connected to the side interface of the second three-way valve. The first gas supply pipe of the PEEK gas supply pipe is connected to the first three-way valve. The second and third gas supply pipes are respectively connected to the fifth three-way valve. The third and fourth gas supply pipes are connected to the third three-way valve. The fifth and sixth gas supply pipes are connected to the fourth three-way valve. The total pressure gauge and the flow restrictor valve are located on the pipe upstream of the first three-way valve.

3. An online carbon and oxygen isotope detection method for carbon monoxide gas, employing the fully automated online carbon and oxygen isotope detection device as described in claim 1 or 2, comprising the following steps: 1) Connect the sample injection assembly, purification assembly, and separation assembly to the carrier gas supply assembly; collect the sample gas into the glass headspace vial, place it in the sample tray, purge the carrier gas He into the headspace vial through a concentric needle, use the carrier gas He to purge the sample gas containing carbon monoxide out of the headspace vial, and remove the H2O and CO2 components from the sample gas through the first drying tube of the purification assembly and the liquid nitrogen cold trap. 2) The purified gas enters the metering loop along with the carrier gas He; 3) After the quantitative loop is filled, switch the 8-way valve to connect the quantitative loop to the 5A molecular sieve column to separate carbon monoxide and nitrogen. 4) The nitrogen gas separated by the 5A molecular sieve column is vented through a 4-way valve; 5) After the nitrogen gas has been completely discharged from the chromatographic column, switch the 4-way valve to connect the chromatographic column to the isotope mass spectrometer. Carbon monoxide gas enters the isotope mass spectrometer to detect carbon and oxygen isotopes. In the above steps, carbon monoxide and nitrogen are separated by a 5A molecular chromatography column, and then the separated nitrogen is discharged by switching a four-way valve. Then, carbon monoxide is introduced into an isotope mass spectrometer for analysis. In step 1), the purge carrier gas He flow rate is 0.5~1.2 mL / min; in step 4), the nitrogen venting flow rate of the separation component is 1~2 mL / min.

4. The online carbon and oxygen isotope detection method for carbon monoxide gas according to claim 3, characterized in that, The filling time for the quantitative ring in step 2) is 120s.

5. The online carbon and oxygen isotope detection method for carbon monoxide gas according to claim 3, characterized in that, In step 3), the column oven temperature is 30°C.

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