Method and sampling system for extending the range of spectral measurement of gas concentration

Abstract

The present application relates to the technical field of using spectroscopy to measure the chemical or physical properties of materials, and in particular to a method and an injection system for expanding the range of spectral measurement of gas concentration. The method includes linearly fitting multiple groups of gas injection volumes with different concentrations and measured peak areas to obtain multiple groups of fitting slopes; linearly fitting multiple groups of fitting slopes and concentrations of multiple groups of gases with different concentrations to obtain standard curves; injecting different volumes of gas to be tested multiple times, and linearly fitting the volumes of multiple groups of gas to be tested and the measured peak areas to obtain K 样品 ; K 样品 Substitute the standard curve to calculate the concentration of the gas to be measured. This method can expand the range of the spectrum beyond the concentration measurement range of the equipment by fitting the slope and concentration, especially solving the problem that the concentration of high-concentration samples is not easy to be accurately measured by the spectral measurement instrument. The injection system of this application is designed for the injection step of this method, making multiple injection operations more convenient and quick.

Description

Technical Field

[0001] The present application relates to the technical field of measuring chemical or physical properties of materials using spectroscopy, and in particular to a method and a sampling system for extending the range of spectral measurement of gas concentration. Background Art

[0002] The use of spectroscopy to measure the concentration of gases such as methane, carbon dioxide, carbon monoxide, etc. has the characteristics of high sensitivity, non-contact measurement, and real-time monitoring, and is widely used in modern industry and environmental monitoring fields.

[0003] Spectral measurement of gas concentration is based on the absorption, emission or scattering characteristics of a substance to light of a specific wavelength. Different gas molecules have unique absorption or emission spectra within a specific spectral range. The concentration of the gas can be determined by measuring the intensity change of light before and after passing through a medium containing the target gas, or by directly measuring the emission spectrum of the gas. In order to ensure the accuracy of spectral measurement, the spectral measurement range is usually relatively narrow. In application environments such as laboratories, different types of instruments need to be purchased for different concentrations, which is relatively expensive. For this reason, a Chinese patent with publication number CN 118010640 A discloses a wide-range photoacoustic spectroscopy gas detection device and method. When the concentration of the gas to be measured is greater than or equal to the preset concentration threshold, the FPGA control board switches to the resonance frequency offset measurement mode for high-concentration gas concentration detection, which is used to solve the problem that the acoustic resonance frequency offset of the resonant photoacoustic cell will increase significantly when the gas concentration increases, resulting in a large error in the PAS measurement result.

[0004] The above method can relatively accurately detect gas concentrations exceeding the preset concentration threshold, but it involves improvements to the internal structure of the instrument, which is relatively complicated. Therefore, the applicant believes that it is necessary to consider from the perspective of calibration methods and design a set of methods that do not change the structure of the instrument itself but can effectively detect gas concentrations exceeding the preset concentration threshold of the instrument, which will more easily expand the range of spectral measurement of gas concentrations. Summary of the invention

[0005] In order to improve the problem that the current method of expanding the range of spectral measurement of gas concentration is relatively complex, the purpose of this application is to provide a method and an injection system for expanding the range of spectral measurement of gas concentration, which can more easily expand the range of spectral measurement of gas concentration, and the measurement accuracy meets the requirements of experiment or detection.

[0006] In order to achieve the purpose of this application, this application provides a method for extending the range of spectral measurement of gas concentration, which adopts the following technical solution:

[0007] A method for extending the range of spectral measurement of gas concentration comprises the following steps:

[0008] S1, linear fitting is performed on multiple groups of gas injection volumes with different concentrations and measured peak areas to obtain multiple groups of fitting slopes;

[0009] S2, performing linear fitting on the multiple groups of fitting slopes and the multiple groups of concentrations of gases with different concentrations to obtain a standard curve;

[0010] S3, inject different volumes of the gas to be tested multiple times, and linearly fit the volumes of multiple groups of the gas to be tested and the measured peak areas to obtain K 样品 ;

[0011] S4, the K 样品 The standard curve is brought in to calculate the concentration of the gas to be measured.

[0012] For gases outside the preset concentration range of the spectral detection equipment, the present application changes different injection volumes, fits the linear relationship between the measured value and the injection volume, obtains the fitting slope of the two, and then uses the obtained fitting slope to correct the actual concentration value, thereby converting the traditional gas concentration obtained by measuring the peak area of ​​the measured gas into the gas concentration calculated by the fitting slope value, so that the gas concentration in the concentration range of 1%~100% can be detected by a spectral instrument, expanding the measuring range of the spectral measuring instrument, especially through a relatively simple method to expand the concentration range of the gas measured by the spectral instrument to a high concentration range of 100%, reducing the laboratory procurement cost, and the measurement accuracy of the fitted standard curve meets the use requirements of experiments or detection.

[0013] Implementations may include any or all of the following features.

[0014] Furthermore, in S1, the injection volume must satisfy the peak area within 1 to 30.

[0015] In the above technical solution, the peak area is controlled by controlling the injection volume to ensure that all gases injected according to this method can obtain relatively accurate peak areas, thereby reducing the error of the fitted standard curve.

[0016] Furthermore, in S1, the concentration of the gas is any integer or non-integer between 1% and 100%.

[0017] Gas data in the range of 1% to 100% of the full range are collected for fitting to ensure the accuracy of the method described in the present technical solution for detecting gas concentration in the range of 1% to 100% of the full range.

[0018] Furthermore, in S1, the higher the concentration of the gas is, the smaller the injection volume is, and the injection volume of the gas in the concentration range of 1% to 100% is between 5 ul and 200 ul.

[0019] Furthermore, the gas injection amount range of 1% concentration is 200 ul~300 ul, the gas injection amount range of 4% concentration is 50 ul~100 ul, the gas injection amount range of 6% concentration is 50 ul~100 ul, the gas injection amount range of 8% concentration is 50 ul~100 ul, the gas injection amount range of 20% concentration is 30 ul~80 ul, the gas injection amount range of 50% concentration is 10 ul~30ul, the gas injection amount range of 75% concentration is 5 ul~25 ul, the gas injection amount range of 80% concentration is 5 ul~25 ul, and the gas injection amount range of 100% concentration is 5 ul~15 ul.

[0020] Since spectral absorption has a linear range, the injection volume of gases with different concentrations should be changed. The injection volume of gases with different concentrations should be adjusted in such a way that the higher the concentration, the smaller the injection volume, to ensure that the peak area is within 1~30, so as to obtain a reliable fitting slope.

[0021] The present application also discloses a sampling system using the above method, comprising a first gas path and a second gas path, wherein the first gas path and the second gas path are connected to a carrier gas, the first gas path is connected to a sample mixing chamber and a dilution chamber in sequence and then connected to a two-position four-way valve; the second gas path is connected to a standard gas mixing chamber and then connected to a two-position four-way valve;

[0022] When the two-position four-way valve is switched to the first connected state, one path of the carrier gas passes through the sample mixing chamber, the dilution chamber, and the two-position four-way valve in sequence along the first gas path and is then emptied to form a sample cleaning gas path; the other path of the carrier gas passes through the standard gas mixed chamber into the spectrometer along the second gas path to form a calibration gas path;

[0023] When the two-position four-way valve is switched to the second connected state, one path of the carrier gas passes through the sample mixing chamber along the first gas path, so that the sample gas injected into the sample mixing chamber passes through the dilution chamber and the two-position four-way valve in sequence with the carrier gas and enters the spectrometer to form a detection gas path; the other path of the carrier gas passes through the standard gas mixing chamber and the two-position four-way valve in sequence and is then emptied to form a standard gas cleaning gas path.

[0024] Further, when the two-position four-way valve is switched to the first communication state, the No. 3 interface of the two-position four-way valve is communicated with the No. 2 interface, and the No. 4 interface is communicated with the No. 1 interface.

[0025] Further, when the two-position four-way valve is switched to the second communication state, the fourth interface and the third interface of the two-position four-way valve are connected, and the second interface and the first interface are connected.

[0026] In the above technical solution, on the one hand, the one-button switching between the sample cleaning gas path, calibration gas path, detection gas path, and standard gas cleaning gas path can be achieved by switching the two-position four-way valve, which is easy to operate, has a low risk of sample contamination, and more reliable measurement results. On the other hand, the sample gas in the detection gas path is first mixed in the sample mixing chamber, and then further mixed and diluted with the carrier gas in the dilution chamber before entering the spectrometer for concentration measurement, which helps to reduce the problem that the measurement results are easily affected when the sample gas concentration is too high.

[0027] Furthermore, the first gas path and the second gas path are respectively connected to a pressure stabilizing valve and a flow meter before being connected to the carrier gas; and the standard gas passes through a flow meter before entering the standard gas mixing chamber.

[0028] Furthermore, the sample gas is injected into the injection port of the sample mixing chamber by extracting the air bag sample through an injection needle, or the air bag sample is injected into the injection port of the sample mixing chamber through an automatic sample injector.

[0029] In summary, the present application provides a method and a sampling system for extending the range of spectral measurement of gas concentration, which has the following beneficial effects:

[0030] First, the present application aims at measuring gases outside the concentration range of the spectral detection equipment, changes different injection volumes, first fits the linear relationship between the measured value and the injection volume, obtains the fitting slope of the two, and then uses the fitting slope and the corresponding concentration value for fitting to correct the true concentration value. Under a certain range of injection volumes, the concentration value is converted through two related linear fits, so that the gas concentration in the concentration range of 1%~100% can be measured, which expands the range of the spectral measuring instrument, and especially solves the problem that the concentration of high-concentration samples is not easy to be accurately measured by the spectral measuring instrument.

[0031] Secondly, the R of the linear fit of this application 2 The value is close to 1, the degree of fitting is high, and the measurement accuracy of the measurement results meets the requirements of experiments or detection.

[0032] Finally, the present application designs a sampling system suitable for the present gas concentration measurement method, and the use of the sampling system makes the multiple sampling operations in the above method more convenient and quick. In addition, the sample gas in the detection gas path of the system is first mixed in the sample mixing chamber, and then further mixed and diluted with the carrier gas in the dilution chamber before entering the spectrometer for concentration measurement, which solves the problem that the measurement results are easily affected when the sample gas concentration is too high. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the method for extending the range of spectral measurement of gas concentration.

[0034] Figure 2It is a linear fitting graph of the injection volume of 20% carbon dioxide concentration and the measured peak area.

[0035] Figure 3 is the multiple-group fitting slope K 1% ~K 100% Linear fitting graph with corresponding gas concentration values.

[0036] Figure 4 It is the gas circuit diagram when the two-position four-way valve is in the first connected state.

[0037] Figure 5 It is the gas circuit diagram when the two-position four-way valve is in the second connected state.

[0038] Description of reference numerals:

[0039] 1. first gas path; 11. first pressure regulating valve; 12. first flow meter; 13. sample mixing chamber; 131. injection port; 14. dilution chamber;

[0040] 2. Second gas path; 21. Second pressure stabilizing valve; 22. Second flow meter; 23. Standard gas mixing chamber;

[0041] 3. Two-position four-way valve; 31. Interface No. 1; 32. Interface No. 2; 33. Interface No. 3; 34. Interface No. 4;

[0042] 4. Carrier gas;

[0043] 5. Standard gas; 51. Third flow meter;

[0044] 6. Sample air bag;

[0045] 7. Spectrum. DETAILED DESCRIPTION

[0046] The following will further illustrate the embodiments of the present invention in conjunction with the accompanying drawings and specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0047] The present application firstly discloses a method for extending the range of spectral measurement of gas concentration. The method is based on the premise that the detection value of the spectrum within the detection range is linearly related to the true concentration.

[0048] For all spectral detection devices, there is a linear relationship within its detection range:

[0049] C 测 =KV 注 +b

[0050] That is, the measured value C 测 The sample injection volume V 注 It is also a linear relationship, so there are two relationships:

[0051] C1=KV1+b(1)

[0052] C2=KV2+b(2)

[0053] V1 and V2 are two different injection volumes of the same sample, and C1 and C2 are the concentration values ​​measured by the spectra of two different injection volumes of the same sample.

[0054] Since it is the same sample, there will be the following relationship:

[0055] C1=C 真 *V1 / (V1+m)

[0056] C2=C 真 *V2 / (V2+m)

[0057] Where m is the carrier gas volume. In spectral detection, m>>V can be achieved, that is, the carrier gas volume is much larger than the sample gas injection volume, so the above two equations can be approximately:

[0058] C1=C 真 *V1 / m (3)

[0059] C2=C 真 *V2 / m (4)

[0060] Formula (2)-(1)

[0061] C2- C1=K (V2- V1)

[0062]

[0063] Formula (4)-(3)

[0064]

[0065] Substitute formula (6) into formula (5):

[0066] C 真 = mK

[0067] That is, the gas concentration value is proportional to the slope of the function C=KV+b.

[0068] With this formula, for gases outside the concentration range measured by the spectral detection equipment, different injection volumes can be changed, and then the linear relationship between the measured value and the injection volume can be fitted to obtain the fitting slope of the two, and then the slope can be used to correct the true concentration value. In order to achieve higher fitting accuracy, multiple gas concentrations in the range of 1% to 100% are selected for fitting. For example, gas concentrations of 1%, 4%, 6%, 8%, 20%, 50%, 75%, 80%, and 100% can be selected for fitting.

[0069] For gases of different concentrations, the injection volume needs to be adjusted. The gas injection volume needs to satisfy the peak area within 1-30. The higher the gas concentration, the smaller the injection volume.

[0070] The following is a detailed description with reference to specific embodiments.

[0071] Reference Figure 1 A method for extending the range of spectral measurement of gas concentration comprises the following steps:

[0072] S1, prepare 9 groups of carbon dioxide gases with concentrations of 1%, 4%, 6%, 8%, 20%, 50%, 75%, 80%, and 100% respectively;

[0073] The carbon dioxide concentration was 20%, and the injection volume was controlled to be between 30 ul and 80 ul for multiple injections, for example, 50 ul, 60 ul, 70 ul and 80 ul were injected respectively, and the peak area results were obtained as shown in Table 1.

[0074] Table 1: 20% concentration of carbon dioxide injection volume and peak area

[0075]

[0076] Linear fitting was performed on the above injection volume and peak area data, and the linear relationship between injection volume and peak area at 20% concentration was obtained as follows: y=0.3171x+0.7935, i.e., K 20% =0.3171, the fitting results are as follows Figure 2 shown.

[0077] According to the above linear fitting process of 20% carbon dioxide concentration injection volume and peak area, the remaining 8 groups of carbon dioxide concentrations were injected with different volumes for multiple times, the peak areas were measured, and the injection volume and peak area were linearly fitted to obtain the fitting slopes K of the remaining 8 groups of concentrations, which were K 1% =0.0138, K 4% =0.066, K 6% =0.1036, K 8% =0.1307, K 20% =0.3171, K 50%=0.6997, K 75% =1.0362, K 80% =1.1031, K 100% =1.4024.

[0078] Among them, the gas injection amount range of 1% concentration is preferably 200 ul~300 ul, the gas injection amount range of 4% concentration is preferably 50 ul~100 ul, the gas injection amount range of 6% concentration is preferably 50 ul~100 ul, the gas injection amount range of 8% concentration is preferably 50 ul~100 ul, the gas injection amount range of 50% concentration is preferably 10 ul~30 ul, the gas injection amount range of 75% concentration is preferably 5 ul~25 ul, the gas injection amount range of 80% concentration is preferably 5 ul~25 ul, and the gas injection amount range of 100% concentration is preferably 5 ul~15 ul.

[0079] S2, for the above 9 groups of fitting slopes K 1% ~K 100% Linear fitting is performed with the concentration values ​​of the above 9 groups of gases with different concentrations to obtain the standard curve C=0.7282K-0.012. The fitting results are as follows: Figure 3 As shown, Figure 3 The y in the figure refers to C in the standard curve, and the x in the figure refers to K in the standard curve.

[0080] S3, take the gas to be tested, inject different volumes of the gas to be tested into the measuring device multiple times, and perform linear fitting based on volume and peak area to obtain K 样品 , K 样品 By inserting the standard curve, the concentration of the gas to be measured can be obtained. The above preferred 6% concentration gas injection volume range and 50% concentration gas injection volume range can be selected for multiple injections. Of course, in actual operation, several concentration injection volume ranges can also be selected for multiple injections. The larger the injection volume range of multiple injections, the easier it is to obtain accurate measurement results.

[0081] The detection equipment used in this embodiment is the carbon isotope detection equipment of Suzhou Guande Energy Technology Co., Ltd., and the sample gas used is carbon dioxide.

[0082] The method of this embodiment can effectively expand the range of spectral detection of gas concentration, especially can be expanded to the gas with the upper limit of spectral detection up to 100% concentration. Various spectral detectors can be used with the data processing front end of the method of this embodiment, and the application range is wide. In experimental sites where the accuracy requirements are not too strict, the equipment procurement cost can be greatly reduced.

[0083] The present application also discloses a sample injection system applied to the above method, and using the sample injection system makes the multiple sample injection operations in the above method more convenient and quick.

[0084] Reference Figure 4 and Figure 5 , the sampling system includes a first gas circuit 1 and a second gas circuit 2, the first gas circuit 1 and the second gas circuit 2 are connected in parallel with the output end of the carrier gas 4, and the carrier gas 4 uses zero-grade air. The first gas circuit 1 is connected to the first pressure-stabilizing valve 11, the first flowmeter 12, the sample mixing chamber 13, and the dilution chamber 14 in sequence, and then connected to the two-position four-way valve 3; the second gas circuit 2 is connected to the second pressure-stabilizing valve 21, the second flowmeter 22, and the standard gas mixing chamber 23 in sequence, and then connected to the two-position four-way valve 3. The first flowmeter 12 can be a mass flow controller. In this embodiment, the first flowmeter 12 uses an air mass flow controller (model: axetrisMFC 2222-1000sccm). The second flowmeter 22 is a mass flow controller, and an air mass flow controller (model: axetrisMFC2222-1000sccm) is used. Before entering the standard gas mixing chamber 23 , the standard gas 5 first passes through a third flow meter 51 , which may be a mass flow controller. In this embodiment, the third flow meter 51 is a carbon dioxide mass flow controller (model: axetrisMFC2222-50 sccm).

[0085] The sample mixing chamber 13 has an injection port 131 for injecting a sample therein. In the above-mentioned measurement method, the sample gas is extracted from the sample gas bag 6 through the injection needle, and injected into the sample mixing chamber 13 from the injection port 131 of the sample mixing chamber 13, or the sample gas bag 6 is injected into the sample mixing chamber 13 through the injection port 131 by an automatic sampler. The injection of the automatic sampler can greatly improve the measurement accuracy and measurement efficiency. The injection port of the standard gas mixing chamber 23 is connected to the standard gas 5 pipeline.

[0086] The two-position four-way valve 3 has a first interface 31 , a second interface 32 , a third interface 33 and a fourth interface 34 , and the first gas circuit 1 and the second gas circuit 2 can be connected to each other in different ways by switching the interfaces.

[0087] Reference Figure 4 When the two-position four-way valve 3 is switched to the first connected state, the No. 3 interface 33 of the two-position four-way valve 3 is connected to the No. 2 interface 32, and the No. 4 interface 34 is connected to the No. 1 interface 31. One path of the carrier gas passes through the sample mixing chamber 13, the dilution chamber 14, the No. 2 interface 32 and the No. 3 interface 33 of the two-position four-way valve 3 in sequence along the first gas path 1 and is then emptied to form a sample cleaning gas path; another path of the carrier gas carries the standard gas injected into the standard gas mixing chamber 23 along the second gas path 2 and passes through the No. 4 interface 34 and the No. 1 interface 31 of the two-position four-way valve 3 in sequence and is then sent into the spectrum 7 to form a calibration gas path;

[0088] Reference Figure 5When the two-position four-way valve 3 is switched to the second connected state, the No. 4 interface 34 of the two-position four-way valve 3 is connected to the No. 3 interface 33, and the No. 2 interface 32 is connected to the No. 1 interface 31. One path of the carrier gas passes through the sample mixing chamber 13 along the first gas path 1, so that the sample gas injected into the sample mixing chamber 13 passes through the dilution chamber 14, the No. 2 interface 32 of the two-position four-way valve, and the No. 1 interface 31 in sequence, and then enters the spectrum 7 to form a detection gas path; the other path of the carrier gas passes through the standard gas mixing chamber 23, the No. 4 interface 34 and the No. 3 interface 33 in sequence, and then is emptied to form a standard gas cleaning gas path.

[0089] In the embodiment of the method, the sample gas selected in step S1 is carbon dioxide, so when the sample is injected into the spectrum detection device using the injection system, the standard gas selected is carbon dioxide. However, the sample gas selected when fitting the standard curve is not limited to carbon dioxide. In other embodiments, the sample gas in step S1 can also be selected from methane, carbon monoxide and other gases. The sample gas selected when fitting the standard curve is adaptively changed according to the applicable gas of the spectrum measurement instrument used, and the standard gas used by the injection system also changes with the change of the sample gas.

[0090] Of course, the above embodiments are the best embodiments of this application, which are only used to illustrate the technical concept and features of this application, and their purpose is to enable people familiar with this technology to understand the content of this application and implement it accordingly, and they cannot be used to limit the protection scope of this application. Any modifications made according to the spirit of the main technical solution of this application should be included in the protection scope of this application.

Claims

1. A method for extending the range of spectral measurement of gas concentration, characterized in that: The following steps are involved: S1, performing linear fitting on multiple groups of gas injection volumes with different concentrations and measured peak areas to obtain multiple groups of fitting slopes, wherein the higher the concentration of the gas, the smaller the injection volume; S2, performing linear fitting on the multiple groups of fitting slopes and the multiple groups of concentrations of gases with different concentrations to obtain a standard curve; S3, inject different volumes of the gas to be tested multiple times, and perform linear fitting with the volumes of multiple groups of the gas to be tested and the measured peak areas to obtain K 样品 ; S4, the K 样品 The standard curve is brought in to calculate the concentration of the gas to be measured.

2. The method for expanding the range of spectral measurement of gas concentration according to claim 1, characterized in that: In S1, the injection volume must satisfy the peak area within 1 to 30.

3. The method for expanding the range of spectral measurement of gas concentration according to claim 2, characterized in that: In S1, the concentration of the gas is any integer or non-integer between 1% and 100%.

4. The method for expanding the range of spectral measurement of gas concentration according to claim 3, characterized in that: In S1, the gas injection volume in the concentration range of 1% to 100% is between 5 ul and 200 ul.

5. The method for expanding the range of spectral measurement of gas concentration according to claim 4, characterized in that: The gas injection volume range of 1% concentration is 200 ul~300 ul, the gas injection volume range of 4% concentration is 50 ul~100 ul, the gas injection volume range of 6% concentration is 50 ul~100 ul, the gas injection volume range of 8% concentration is 50 ul~100 ul, the gas injection volume range of 20% concentration is 30 ul~80 ul, the gas injection volume range of 50% concentration is 10 ul~30 ul, the gas injection volume range of 75% concentration is 5 ul~25 ul, the gas injection volume range of 80% concentration is 5 ul~25 ul, and the gas injection volume range of 100% concentration is 5 ul~15 ul.

6. A sample injection system used in the method according to any one of claims 1 to 5, characterized in that: It comprises a first gas path and a second gas path, wherein the first gas path and the second gas path are connected to the carrier gas, the first gas path is connected to the sample mixing chamber and the dilution chamber in sequence and then connected to a two-position four-way valve; the second gas path is connected to the standard gas mixing chamber and then connected to the two-position four-way valve; When the two-position four-way valve is switched to the first connected state, one path of the carrier gas passes through the sample mixing chamber, the dilution chamber, and the two-position four-way valve in sequence along the first gas path and is then emptied to form a sample cleaning gas path; the other path of the carrier gas passes through the standard gas mixed chamber into the spectrometer along the second gas path to form a calibration gas path; When the two-position four-way valve is switched to the second connected state, one path of the carrier gas passes through the sample mixing chamber along the first gas path, so that the sample gas injected into the sample mixing chamber passes through the dilution chamber and the two-position four-way valve in sequence with the carrier gas and enters the spectrometer to form a detection gas path; the other path of the carrier gas passes through the standard gas mixing chamber and the two-position four-way valve in sequence and is then emptied to form a standard gas cleaning gas path.

7. The sample injection system according to claim 6, characterized in that: When the two-position four-way valve is switched to the first communication state, the No. 3 interface of the two-position four-way valve is communicated with the No. 2 interface, and the No. 4 interface is communicated with the No. 1 interface.

8. The sample injection system according to claim 7, characterized in that: When the two-position four-way valve is switched to the second communication state, the fourth interface of the two-position four-way valve is communicated with the third interface, and the second interface is communicated with the first interface.

9. The sample injection system according to claim 8, characterized in that: The first gas path and the second gas path are connected with a pressure stabilizing valve and a flow meter before being connected with the carrier gas; the standard gas passes through a flow meter before entering the standard gas mixing chamber.

10. The sampling system according to claim 9, wherein the sample gas is injected into the sampling port of the sample mixing chamber by extracting the air bag sample through an injection needle, or the air bag sample is injected into the sampling port of the sample mixing chamber through an automatic sample injector.

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