A CH4 Gas Detection Device and Method in a Saturated Pressure Chamber

Abstract

The present invention discloses a CH4 gas detection device in a saturation pressure chamber, which includes a sampling tube, a sample chamber, an electron impact ionization source, a mass spectrometry chamber, and a mass spectrometry detector. The sampling tube is located on one side of the sample chamber and is internally connected to the processing chamber, and is used to guide the sample gas containing CH4 in the saturation pressure chamber into the sample chamber. The mass spectrometry detector is located inside the mass spectrometry chamber, and the ion detection inlet is coaxial with the small hole at the left end of the mass spectrometry chamber. The electron impact ionization source is located inside the mass spectrometry detector, and the ion inlet is coaxial with the small hole at the left end of the mass spectrometry chamber. The outlet of the sample chamber is connected to the inlet of the oxygen adsorption chamber through a first pipeline, and the outlet of the oxygen adsorption chamber is connected to the mixing chamber through a second pipeline. A compensation gas pipeline is also provided on the side wall of the mixing chamber. By optimizing the processing process of the gas sample and improving the mass spectrometry detection method, the present invention can effectively reduce the interference of oxygen on methane detection and improve the detection accuracy of CH4 gas in the saturation pressure chamber.

Description

Technical Field

[0001] This application belongs to the field of analytical detection, and particularly relates to a CH4 gas detection device and method in a saturation pressure chamber. Background Art

[0002] Deep saturation diving operations refer to long-term diving work where divers are directly exposed to depths exceeding 120 meters (even up to 300 - 500 meters) underwater. In such diving methods, divers first need to stay in a high-pressure environment chamber for a long time to adapt to the high-pressure environment at great depths underwater, and then directly enter and exit the great depths underwater to carry out work, with a duration of up to 1 month. Through diving medicine, it is known that the gas in such high-pressure environment chambers generally consists of a mixture of helium, oxygen, and small amounts of carbon dioxide, water, and nitrogen. When divers adapt to the high-pressure environment and rest in the high-pressure environment chamber, they need to intake oxygen and exhale carbon dioxide at the same time to maintain their own health needs.

[0003] During this process, methane, as a potential gas pollutant, may accumulate in the chamber, posing a threat to the health and safety of divers. Therefore, it is crucial to monitor the methane concentration in the saturation pressure chamber in real time to ensure the health and safety of divers in the high-pressure environment. However, when detecting methane gas in the saturation pressure chamber, the concentration of methane is low, and it is easily interfered by oxygen during detection. In the electron impact ionization process, oxygen molecules will generate oxygen atomic ions (O + , M / Z 16), whose mass-to-charge ratio is the same as that of methane ions (CH4 + , M / Z 16). This signal overlap will lead to inaccuracies in the measurement of methane concentration, and effective methods must be found to distinguish or remove these interferences. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology and to achieve accurate monitoring of CH4 in the saturation pressure chamber, the present invention provides a CH4 gas detection method and device in the saturation pressure chamber. By optimizing the processing process of gas samples and improving the mass spectrometry detection method, the interference of oxygen on methane detection can be effectively reduced, and the detection accuracy can be improved.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A CH4 gas detection device in a saturated pressure chamber includes a sampling tube, a sample chamber, an electron impact ionization source, a mass spectrometry chamber, and a mass spectrometry detector. The sampling tube is located on one side of the sample chamber and is internally connected to the processing chamber, and is used to guide the sample gas containing CH4 in the saturated pressure chamber into the sample chamber. The mass spectrometry detector is located inside the mass spectrometry chamber, and the ion detection inlet is coaxial with the small hole at the left end of the mass spectrometry chamber. The electron impact ionization source is located inside the mass spectrometry detector, and the ion inlet is coaxial with the small hole at the left end of the mass spectrometry chamber. The outlet of the sample chamber is connected to the inlet of the oxygen adsorption chamber through a first pipeline, and the outlet of the oxygen adsorption chamber is connected to the mixing chamber through a second pipeline. A suction pump is provided on the second pipeline. A first pressure sensor is provided in the sample chamber, a second pressure sensor is provided in the mixing chamber, and a compensation gas pipeline is further provided on the side wall of the mixing chamber. The outlet of the mixing chamber is connected to the small hole at the left end of the mass spectrometry chamber through a third pipeline.

[0006] Preferably, a first electrically controlled valve is provided on the third pipeline, and a second electrically controlled valve is provided on the compensation gas pipeline.

[0007] Preferably, the second electrically controlled valve is electrically connected to the first pressure sensor and the second pressure sensor, and the second electrically controlled valve is configured to adjust the valve opening based on the pressure difference feedback by the first pressure sensor and the second pressure sensor.

[0008] Preferably, the electron energy emitted by the electron impact ionization source is selected as 70 eV, and there are ion transmission small holes on both the left and right sides of the electron impact ionization source.

[0009] Preferably, it further includes a molecular pump for the mass spectrometry chamber, and the inlet of the molecular pump for the mass spectrometry chamber is connected to the mass spectrometry chamber.

[0010] Preferably, the oxygen adsorption chamber is a cylindrical shell, its air inlet is located on the side of the shell, and the exhaust port is located at the top of the shell. A spiral channel is arranged in the oxygen adsorption chamber, and an oxygen adsorbent is coated on the wall surface of the spiral channel.

[0011] Preferably, the cylindrical shell includes a lower base and an upper cover. The spiral channel is the space enclosed by the spiral partition on the lower base, the lower base, and the upper cover. The exhaust port is arranged at the center of the upper cover and corresponds to the center of the spiral channel. The lower base, the upper cover, and the spiral partition are detachably connected.

[0012] The present invention also discloses a CH4 gas detection method based on the above CH4 gas detection device in a saturated pressure chamber, including the following steps:

[0013] S1, Sample gas introduction: Introduce the sample gas containing CH4 in the saturated pressure chamber into the sample chamber through the sampling tube. After the gas inlet is completed, detect the pressure in the sample chamber and use it as the preset standard pressure;

[0014] S2, Oxygen removal: The sample gas enters the oxygen adsorption chamber from the outlet of the sample chamber through the first pipeline. The sample gas passes through the spiral channel coated with oxygen adsorbent in the oxygen adsorption chamber to effectively remove the oxygen in the sample gas. The sample gas after oxygen removal enters the mixing chamber through the second pipeline;

[0015] S3, Pressure regulation: In the mixing chamber, automatically adjust the valve opening of the second electronically controlled valve according to the pressure difference feedback by the first pressure sensor and the second pressure sensor, so that the pressure of the sample gas reaches the preset standard pressure;

[0016] S4, Sample gas enters the mass spectrometry chamber: The sample gas after pressure adjustment enters the mass spectrometry chamber through the third pipeline;

[0017] S5, Electron impact ionization: The sample gas is ionized in the mass spectrometry chamber through an electron impact ionization source with an electron energy of 70 eV to form a plasma including CH4 + ions;

[0018] S6, Mass spectrometry detection: Detect the signal intensities of M / Z16 and M / Z 32 in the plasma through a mass spectrometry detector;

[0019] S7, Data processing: Determine the concentration of CH4 in the sample gas according to the signal intensities of M / Z16 and M / Z 32 in the plasma.

[0020] Preferably, step S7 further includes: determining the sum of the signal intensity of O + signal intensity and CH4 + signal intensity according to the signal intensity of M / Z16 in the plasma, determining the signal intensity of O2 + signal intensity according to the signal intensity of M / Z 32 in the plasma; based on the correlation relationship between the signal intensity of O + signal intensity and the signal intensity of O2 + in the plasma, determining the signal intensity of CH4 + in the plasma, and determining the concentration of CH4 in the sample gas according to the signal intensity of CH4 + in the plasma..

[0021] Preferably, the compensation gas is nitrogen or an inert gas.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The present invention effectively reduces the oxygen content in the sample gas by providing an oxygen adsorption chamber and utilizing a spiral channel coated with an oxygen adsorbent, thereby reducing the interference of oxygen on methane detection and ensuring the accuracy of the detection results. Pressure sensors are provided in the sample chamber and the mixing chamber, and a compensating gas pipeline is provided in the mixing chamber. By monitoring and adjusting the pressure, the sample gas is ensured to be detected under standard pressure, thereby enhancing the stability and reliability of the detection process.

[0024] (2) The present invention uses an electron bombardment ionization source to ionize the sample gas with an electron energy of 70 eV, and the mass spectrometer detector detects CH4 + The mass-to-charge ratio signal of the ion realizes high sensitivity and high selectivity detection of methane. + Signal strength real-time calculation + The signal intensity of M / Z 16 was subtracted from the total signal of + Signal strength, get accurate CH4 + The signal strength is used to calculate the CH4 gas concentration, which solves the oxygen interference problem and improves the accuracy of the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0026] Figure 1 This is an overall schematic diagram of a CH4 gas detection device in a saturated pressurized cabin according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the exterior of the oxygen adsorption chamber according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the interior of the oxygen adsorption chamber according to an embodiment of the present invention;

[0029] Figure 4 The figure is a flow chart of a method for detecting CH4 gas in a saturated pressurized cabin according to an embodiment of the present invention.

[0030] Reference numerals: 1 - sample injection tube; 2 - sample chamber; 3 - electron impact ionization source; 4 - mass spectrometry chamber; 5 - mass spectrometry detector; 6 - first pipeline; 7 - oxygen adsorption chamber; 71 - air inlet; 72 - air outlet; 73 - spiral channel; 74 - lower base; 75 - upper cover; 76 - spiral partition; 8 - second pipeline; 9 - mixing chamber; 10 - air extraction pump; 11 - first pressure sensor; 12 - second pressure sensor; 13 - compensation gas pipeline; 14 - third pipeline; 15 - first electrically controlled valve; 16 - second electrically controlled valve; 17 - molecular pump for mass spectrometry chamber. Detailed implementation manners

[0031] For the convenience of understanding the present invention, the present invention will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is expressed as "fixed to" another element, it can be directly on the other element, or there can be one or more intermediate elements therebetween. When an element is expressed as "connected to" another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. The terms "vertical", "horizontal", "left", "right", "inner", "outer" and similar expressions used in this specification are only for the purpose of illustration. In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating relative importance or implicitly indicating the quantity of the indicated technical features. Thus, unless otherwise stated, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features; the meaning of "a plurality" is two or more. The term "comprising" and any deformation thereof mean non-exclusive inclusion, and there may be or be added one or more other features, integers, steps, operations, units, components and / or their combinations.

[0032] In addition, unless otherwise clearly defined and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. All technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0033] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Please refer to Figures 1-3, this embodiment provides a CH4 gas detection device in a saturated pressure chamber, including a sampling tube 1, a sample chamber 2, an electron impact ionization source 3, a mass spectrometry chamber 4, and a mass spectrometry detector 5. The sampling tube 1 is located on one side of the sample chamber 2 and is internally connected to the processing chamber, and is used to guide the sample gas containing CH4 in the saturated pressure chamber into the sample chamber 2. This design ensures that the sample gas can be effectively introduced into the sample chamber 2 for subsequent gas processing and analysis.

[0035] The mass spectrometry detector 5 is located inside the mass spectrometry chamber 4, and the ion detection inlet is coaxial with the small hole at the left end of the mass spectrometry chamber 4, ensuring that the ion signal can be accurately detected. The electron impact ionization source 3 is located inside the mass spectrometry detector 5, and the ion inlet is coaxial with the small hole at the left end of the mass spectrometry chamber 4. The sample gas is ionized by the electron impact ionization source 3 with an electron energy of 70 eV to generate CH4 + ions for detection. The mass spectrometry detector 5 can adopt a quadrupole mass spectrometry structure, which can screen and detect ions through the electric field formed by four parallel electrode rods. Quadrupole mass spectrometry has the advantages of high resolution and high sensitivity, and can accurately separate and detect ions of different masses, so as to realize the precise analysis of the components of complex sample gases.

[0036] The outlet of the sample chamber 2 is connected to the inlet of the oxygen adsorption chamber 7 through the first pipeline 6. The oxygen adsorption chamber 7 is used to remove oxygen in the sample gas to reduce the interference of oxygen on the subsequent detection of CH4. The outlet of the oxygen adsorption chamber 7 is connected to the mixing chamber 9 through the second pipeline 8. A suction pump 10 is arranged on the second pipeline 8, and the suction pump 10 is used to drive the gas flow in the pipeline. A first pressure sensor 11 is arranged in the sample chamber 2 to monitor the gas pressure in the sample chamber and ensure a stable pressure environment during the detection process. A second pressure sensor 12 is arranged in the mixing chamber 9 to monitor the pressure in the mixing chamber. A compensation gas pipeline 13 is also arranged on the side wall of the mixing chamber 9, and the compensation gas pipeline 13 is used to supplement and adjust the gas components during the detection process to maintain the accuracy of the detection. The outlet of the mixing chamber 9 is connected to the small hole at the left end of the mass spectrometry chamber 4 through the third pipeline 14 to ensure that the processed sample gas enters the mass spectrometry chamber 4 for final detection and analysis.

[0037] A first electrically controlled valve 15 is provided on the third pipeline 14. The first electrically controlled valve 15 is used to control the gas flow rate through the third pipeline 14 to ensure that the gas flow before entering the mass spectrometry chamber 4 is controllable. A second electrically controlled valve 16 is provided on the compensation gas pipeline 13. The second electrically controlled valve 16 is used to adjust the flow rate of the compensation gas, so as to ensure that the gas composition and pressure in the mixing chamber 9 meet the expected requirements. The second electrically controlled valve 16 is electrically connected to the first pressure sensor 11 and the second pressure sensor 12, and controls the opening degree of the second electrically controlled valve 16 based on the pressure difference feedback by the first pressure sensor 11 and the second pressure sensor 12. Specifically, the first pressure sensor 11 detects the pressure in the sample chamber 2, which is the standard pressure and is used to provide a reference pressure value. The second pressure sensor 12 detects the pressure in the mixing chamber 9. Since the pressure in the mixing chamber 9 is lower than that in the sample chamber 2, the pressure is restored to the standard pressure of the sample chamber 2 by adding compensation gas for mixing. In this way, through real-time monitoring and feedback adjustment, the pressure and composition of the gas in the mixing chamber 9 are ensured to be stable, thereby improving the accuracy and reliability of the detection results.

[0038] The electron energy emitted by the electron impact ionization source 3 is selected as 70 eV. This energy selection can effectively ionize methane molecules in the sample gas to generate CH4 + ions. The energy selection of 70 eV can generate representative ion fragments during the ionization process. Especially for oxygen (O2) molecules, under the condition of 70 eV, the oxygen molecules may undergo the following ionization processes: Direct ionization: O2 → O2 + + e - And atomic ion generation: O2 → O + + O - ; Although the ionization energies of these two ionization methods are different, the proportional relationship between the generated O + and O2 + ions remains relatively fixed under the condition of 70 eV. This fixed proportional relationship enables the interference of O + to be corrected by measuring the signal intensity of O2 + , so as to accurately calculate the signal intensity of CH4 and improve the accuracy and reliability of the detection. Compared with other electron energy conditions, 70 eV can not only effectively ionize most organic molecules, but also avoid excessive fragmentation under high energy conditions and insufficient ionization efficiency under low energy conditions, ensuring the stability and consistency of the mass spectrometry detection results.

[0039] There are ion transport small holes on both the left and right sides of the electron impact ionization source 3, which do not affect the transport of photoionization product ions. This design ensures that the ions generated during the ionization process can be efficiently transported to the mass spectrometry detector 5, improving the sensitivity and accuracy of detection. The device also includes a mass spectrometry chamber molecular pump 17, whose inlet is connected to the mass spectrometry chamber 4. Through the mass spectrometry chamber molecular pump 17, the vacuum environment inside the mass spectrometry chamber 4 can be maintained, thus ensuring the accuracy and stability of mass spectrometry detection.

[0040] Please refer to Figures 2-3 , the oxygen adsorption chamber 7 is a cylindrical shell, whose air inlet 71 is located on the side of the shell, and the exhaust port 72 is located at the top of the shell, ensuring that the gas can flow smoothly inside the shell and maximizing the contact surface with the oxygen adsorbent. A spiral channel 73 is arranged inside the oxygen adsorption chamber 7, and the wall surface of the spiral channel 73 is coated with an oxygen adsorbent, increasing the contact area between the gas and the adsorbent and improving the oxygen adsorption efficiency. The cylindrical shell includes a lower base 74 and an upper cover 75. The spiral channel 73 is formed by the space enclosed by the spiral partition 76 on the lower base 74, the lower base 74, and the upper cover 75. The exhaust port 72 is arranged at the center position of the upper cover 75, corresponding to the center of the spiral channel 73, ensuring that the gas after adsorption treatment can be discharged smoothly. The lower base 74, the upper cover 75, and the spiral partition 76 are detachably connected, facilitating the maintenance and replacement of the adsorbent. The oxygen adsorbent can be selected from palladium-based catalysts (Pd / Al2O3), platinum-based catalysts (Pt / Al2O3), etc. The selection principle of the oxygen adsorbent is that it can effectively adsorb oxygen but does not adsorb CH4.

[0041] Please refer to Figure 4 , another embodiment of the present invention also discloses a CH4 gas detection method based on the above-mentioned CH4 gas detection device in the saturated pressure chamber, including the following steps:

[0042] S1, sample gas introduction: The sample gas containing CH4 in the saturated pressure chamber is introduced into the sample chamber 2 through the sampling tube 1. After the intake is completed, the pressure in the sample chamber 2 is detected and used as the preset standard pressure. In this process, the sampling tube 1 ensures that the sample gas can enter the sample chamber 2 smoothly for subsequent processing. In some embodiments, after inputting a set volume of sample gas into the sample chamber 2, the pressure in the sample chamber 2 can be detected by the first pressure sensor 11 and used as the preset standard pressure. In other embodiments, the pressure in the sample chamber 2 can be used as the intake cut-off condition. For example, the pressure in the sample chamber 2 is detected in real time by the first pressure sensor 11, and the intake is stopped when the pressure reaches the preset standard pressure. The preset standard pressure can be specifically set according to the pressure of the intake pipeline and the requirements of the sample chamber.

[0043] S2, Oxygen removal: The sample gas enters the oxygen adsorption chamber 7 from the outlet of the sample chamber 2 through the first pipeline 6. The sample gas passes through the spiral channel 73 coated with an oxygen adsorbent in the oxygen adsorption chamber 7 to effectively remove the oxygen in the sample gas. The removal of oxygen is to reduce its interference with the subsequent CH4 detection. The sample gas after oxygen removal enters the mixing chamber 9 through the second pipeline 8.

[0044] S3, Pressure regulation: In the mixing chamber 9, the valve opening of the second electronically controlled valve 16 is automatically adjusted according to the pressure difference feedback by the first pressure sensor 11 and the second pressure sensor 12, so that the pressure of the sample gas in the mixing chamber 9 reaches the preset standard pressure. The first pressure sensor 11 detects the pressure of the sample chamber 2, and this pressure is the standard pressure, providing a reference pressure value; the second pressure sensor 12 detects the pressure of the mixing chamber 9. If the pressure of the mixing chamber 9 is lower than that of the sample chamber 2, mixing is carried out by adding compensation gas to restore its pressure to the preset standard pressure. In this way, through real-time monitoring and feedback regulation, the pressure and composition of the gas in the mixing chamber 9 are ensured to be stable. The compensation gas is nitrogen or an inert gas. The selection of these gases can avoid interference with the detection process, while maintaining the standard pressure in the processing chamber 2, ensuring the stability and accuracy of the entire detection process.

[0045] S4, Sample gas enters the mass spectrometry chamber: The sample gas after pressure adjustment enters the mass spectrometry chamber 4 through the third pipeline 14. The third pipeline 14 ensures that the sample gas after adjustment and treatment can smoothly enter the mass spectrometry chamber 4, preparing for mass spectrometry analysis.

[0046] S5, Electron impact ionization: The sample gas is ionized in the mass spectrometry chamber 4 by the electron impact ionization source 3 with an electron energy of 70 eV to form CH4 + ions. The electron impact ionization source 3 ionizes the CH4 molecules in the sample gas by electron impact to form CH4 + ions that can be detected by mass spectrometry. The electron energy of 70 eV is the standard ionization energy, ensuring the efficiency and stability of the ionization process.

[0047] S6, Mass spectrometry detection: The ionized CH4+ ions are detected in the mass spectrometry chamber 4 by the mass spectrometry detector 5, and the mass spectrometry detector 5 identifies the signal intensities of M / Z 16 and M / Z 32. The signal intensity of M / Z 16 refers to the signal intensity of ions with a mass-to-charge ratio of 16, such as CH4 + 、O + ions; The signal intensity of M / Z 32 refers to the signal intensity of ions with a mass-to-charge ratio of 32, such as O2 + ions. The mass spectrometry detector 5 is the core component of the detection process and can respectively identify and analyze the signal intensities with a mass-to-charge ratio (M / Z) of 16 and 32.

[0048] S7, data processing: according to the signal intensity of M / Z16 and M / Z 32 in the ion body, determine the CH4 + Signal strength.

[0049] In some embodiments, step S7 further includes: determining the + Signal strength and CH4 + The sum of the signal intensities, based on the signal intensity of M / Z 32 in the ion, determines O2 + Signal intensity; based on O in ions + Signal Strength and O2 + The correlation of signal intensity determines the CH4 + Signal intensity, and according to the CH4 + The signal intensity determines the concentration of CH4 in the sample gas. S8, result output: output the detection result.

[0050] The oxygen in the sample gas in the processing chamber 2 is adsorbed by the oxygen adsorbent coated on the spiral channel 93 of the oxygen adsorption chamber 9. Although most of the oxygen is removed, a small amount of residual oxygen is still inevitable. When the sample gas after preliminary treatment enters the mass spectrometer chamber 4, it is ionized by the 70eV electron bombardment ionization source 3. The generated ions include CH4 + and O2 + , O + ions. Due to O + Ions and CH4 + The mass-to-charge ratio of CH4 is 16, which will affect the + The signal strength of m / z 16 causes interference, and the system uses O2 + Real-time calculation of signal strength + The signal intensity of M / Z 16 was calculated and subtracted from the total signal of M / Z 16. + Signal strength, thus obtaining accurate CH4 + This dual treatment method, which combines oxygen adsorption with 70 eV electron bombardment, can effectively remove O + The interference with the detection results ensures the accurate measurement of CH4 concentration. Through this combined method, not only the efficiency of sample gas processing is improved, but also the accuracy and reliability of methane detection are significantly improved.

[0051] In summary, the present invention provides a CH4 gas detection device and its detection method in a saturated pressure chamber, which have significant advantages and innovations. In the sample gas processing part, by setting the oxygen adsorption chamber 7 and using the spiral channel 73 coated with oxygen adsorbent, the oxygen content in the sample gas is effectively reduced, thereby reducing the interference of oxygen on methane detection. Combining the use of a pressure sensor and the compensation gas pipeline 13 ensures the pressure stability in the mixing chamber 9 and enhances the stability and reliability of the detection process. In the mass spectrometry detection part, an electron impact ionization source 3 with 70 eV is adopted, which can efficiently ionize methane molecules to generate CH4 + ions. The ions are detected by the mass spectrometry detector 5, and by using the O2 + signal intensity to calculate the O + signal intensity in real time, subtracting the O + signal intensity from the total M / Z 16 signal intensity to obtain the accurate CH4 + signal intensity, and thus accurately calculating the CH4 gas concentration. This dual processing method not only improves the efficiency of gas sample processing but also significantly enhances the accuracy and reliability of methane detection. Generally speaking, the present invention solves the oxygen interference problem by optimizing the processing and detection processes of gas samples, realizes the efficient and accurate detection of CH4 gas in a saturated pressure chamber, and is of great significance for ensuring the health and safety of divers in a high-pressure environment. The device and method are not only applicable to methane detection in a saturated pressure chamber but also can be applied to gas detection in other high-pressure environments, having a wide range of application prospects.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A CH4 gas detection device in a saturated pressure chamber, characterized in that: It includes an injection tube (1), a sample chamber (2), an electron impact ionization source (3), a mass spectrometry chamber (4), and a mass spectrometry detector (5). The injection tube (1) is located on one side of the sample chamber (2) and is internally connected to the sample chamber (2) for guiding the sample gas containing CH4 in the saturated pressurized chamber into the sample chamber (2). The mass spectrometry detector (5) is located inside the mass spectrometry chamber (4), and the ion detection inlet is coaxial with the small hole at the left end of the mass spectrometry chamber (4). The electron impact ionization source (3) is located inside the mass spectrometry detector (5), and the ion inlet is coaxial with the small hole at the left end of the mass spectrometry chamber (4). The outlet of the sample chamber (2) is connected to the inlet of an oxygen adsorption chamber (7) through a first pipeline (6). The outlet of the oxygen adsorption chamber (7) is connected to a mixing chamber (9) through a second pipeline (8). A suction pump (10) is provided on the second pipeline (8). A first pressure sensor (11) is provided inside the sample chamber (2), and a second pressure sensor (12) is provided inside the mixing chamber (9). A compensation gas pipeline (13) is also provided on the side wall of the mixing chamber (9). The outlet of the mixing chamber (9) is connected to the small hole at the left end of the mass spectrometry chamber (4) through a third pipeline (14). A first electrically controlled valve (15) is provided on the third pipeline (14), and a second electrically controlled valve (16) is provided on the compensation gas pipeline (13). The second electrically controlled valve (16) is electrically connected to the first pressure sensor (11) and the second pressure sensor (12), and the second electrically controlled valve (16) is configured to adjust the valve opening based on the pressure difference feedback by the first pressure sensor (11) and the second pressure sensor (12), and perform mixing by adding compensation gas to restore the pressure in the mixing chamber (9) to the standard pressure of the sample chamber (2).

2. The CH4 gas detection device in a saturated pressure chamber according to claim 1, wherein: The electron energy emitted by the electron impact ionization source (3) is selected as 70 eV, and there are ion transmission small holes on both the left and right sides of the electron impact ionization source (3).

3. The CH4 gas detection device in a saturated pressure chamber according to claim 2, characterized in that: It further includes a mass spectrometry chamber molecular pump (17), and the inlet of the mass spectrometry chamber molecular pump (17) is connected to the mass spectrometry chamber (4).

4. The CH4 gas detection device in a saturated pressure chamber according to claim 3, characterized in that: The oxygen adsorption chamber (7) is a cylindrical shell, its air inlet (71) is located on the side of the shell, and the exhaust port (72) is located at the top of the shell. A spiral channel (73) is arranged inside the oxygen adsorption chamber (7), and an oxygen adsorbent is coated on the wall surface of the spiral channel (73).

5. The CH4 gas detection device in a saturated pressure chamber according to claim 4, wherein: The cylindrical shell includes a lower base (74) and an upper cover (75). The spiral channel (73) is the space enclosed by a spiral partition (76) on the lower base (74), the lower base (74), and the upper cover (75). The exhaust port (72) is arranged at the center position of the upper cover (75) and corresponds to the center of the spiral channel (73). The lower base (74), the upper cover (75), and the spiral partition (76) are detachably connected.

6. A CH4 gas detection method for the CH4 gas detection device in the saturated pressure chamber according to any one of claims 1-5, characterized in that, It includes the following steps: S1, Sample gas introduction: Introduce the sample gas containing CH4 in the saturated pressurized chamber into the sample chamber (2) through the injection tube (1). After the intake is completed, detect the pressure inside the sample chamber (2) and use it as the preset standard pressure; S2, Oxygen removal: The sample gas enters the oxygen adsorption chamber (7) from the outlet of the sample chamber (2) through the first pipeline (6). The sample gas passes through the spiral channel (73) coated with an oxygen adsorbent in the oxygen adsorption chamber (7), effectively removing the oxygen in the sample gas. The sample gas after oxygen removal enters the mixing chamber (9) through the second pipeline (8); S3, Pressure regulation: In the mixing chamber (9), the valve opening of the second electronically controlled valve (16) is automatically adjusted according to the pressure difference feedback by the first pressure sensor (11) and the second pressure sensor (12), so that the pressure of the sample gas reaches the preset standard pressure; S4, Sample gas enters the mass spectrometry chamber: The sample gas after pressure adjustment enters the mass spectrometry chamber (4) through the third pipeline (14); S5, Electron impact ionization: The sample gas is ionized in the mass spectrometry chamber (4) by an electron impact ionization source (3) at an electron energy of 70 eV to form a plasma including CH4 + ions; S6, Mass spectrometry detection: The signal intensities of M / Z16 and M / Z 32 in the plasma are detected by the mass spectrometry detector (5); S7, Data processing: Determine the concentration of CH4 in the sample gas according to the signal intensities of M / Z 16 and M / Z 32 in the plasma; determine the O + signal intensity and the sum of the CH4 + signal intensities, and determine the O2 signal intensity according to the signal intensity of M / Z 32 in the plasma + ; based on the correlation between the O + signal intensity and the O2 + signal intensity, determine the CH4 signal intensity in the plasma + , and determine the concentration of CH4 in the sample gas according to the CH4 + signal intensity in the plasma.

7. The CH4 gas detection method according to claim 6, characterized in that, The compensation gas is nitrogen or an inert gas.

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