Gas chromatography valve system for analyzing nitrogen trifluoride gas content in carbon tetrafluoride and method of using same

Abstract

The application discloses a gas chromatography valve path system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride and a use method thereof, and comprises one ten-way valve, one quantitative ring, three chromatographic columns and one detector, and comprises the following steps: (1) setting a valve event 0 min on the gas chromatography workstation, the state of the ten-way valve is "off", and carbon tetrafluoride sample gas enters a recovery pipeline; (2) setting a valve event 5 min on the gas chromatography workstation, the ten-way valve is "on", and the carbon tetrafluoride sample gas can enter the detector to analyze the peak. The method solves the problems of great operation difficulty, inaccurate measurement, and incomplete separation of the main component carbon tetrafluoride and the impurity component nitrogen trifluoride in the prior art, the valve path system is clear, the operation is simple and convenient, and the analysis is accurate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of quantitative detection of carbon tetrafluoride, and particularly relates to a gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride and a use method thereof. BACKGROUND

[0002] Carbon tetrafluoride is a colorless and odorless gas, which is currently used in large quantities in the microelectronics industry, and its high-purity gas is widely used in the etching of silicon, silicon dioxide, and tungsten thin film materials. The existing production method is mainly electrolysis, and the crude nitrogen trifluoride gas produced by electrolysis contains many impurity gases. Among them, NF3 is difficult to separate on the chromatographic column because of its similar physical properties to CF4, so it is relatively difficult to analyze using gas chromatography.

[0003] The prior art method for analyzing nitrogen trifluoride in carbon tetrafluoride uses helium as the carrier gas, HaysepQ packed column as the pre-separation column, HaysepR packed column as the separation column, and analyzes by a helium ionization detector. The disadvantages of this scheme are:

[0004] Firstly, the separation of nitrogen trifluoride and carbon tetrafluoride components is not good, and nitrogen trifluoride and carbon tetrafluoride cannot be completely separated on the chromatogram, resulting in inaccurate quantification.

[0005] Secondly, the existing scheme uses a valve cutting method, and the peak times of nitrogen trifluoride and carbon tetrafluoride on the chromatogram are close, making it difficult to cut;

[0006] Thirdly, this method requires very high stability of the carrier gas flow, and slight changes in carrier gas pressure will result in inaccurate valve movement time settings, leading to inaccurate test results for the content of nitrogen trifluoride;

[0007] Fourthly, the helium ionization gas chromatograph is relatively expensive. SUMMARY

[0008] To solve the above problems, the present application provides a gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride and a use method thereof, which can effectively solve the problems of high operation difficulty, high stability requirement of carrier gas flow, and inaccurate measurement of the prior art valve cutting method.

[0009] One of the purposes of the present application is to provide a gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride, which comprises a ten-way valve, a quantitative ring and a detector, the first interface of the ten-way valve is connected with a sample outlet, the second interface of the ten-way valve is connected with a sample inlet, the third interface and the tenth interface of the ten-way valve are provided with a quantitative ring, the fifth interface and the ninth interface of the ten-way valve are provided with a first chromatographic column, the sixth interface of the ten-way valve is connected with the detector in sequence through a second chromatographic column and a third chromatographic column, and the eighth interface of the ten-way valve is connected with a vent.

[0010] As a preferred solution, the fourth interface and the seventh interface of the ten-way valve are connected with a helium source, and the detector is connected with a hydrogen source and an air source respectively.

[0011] As a preferred solution, the fourth interface and the seventh interface of the ten-way valve are connected with the helium source through a pressure stabilizing valve.

[0012] As a preferred solution, the pressure stabilizing valve is arranged between the detector and the hydrogen source and the air source respectively.

[0013] As a preferred solution, a needle valve is arranged between the eighth interface of the ten-way valve and the vent.

[0014] As a preferred solution, the first chromatographic column and the second chromatographic column adopt Hayesep Q chromatographic columns, and the third chromatographic column adopts a Hayesep T chromatographic column.

[0015] As a preferred solution, the sample outlet is connected with an external rotor flow meter and then enters a tail gas recovery pipeline.

[0016] The second purpose of the present application is to provide a use method of a gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride, and the specific steps are as follows: when the ten-way valve is in a closed state and the chromatography system is in an initial state of analysis and detection, the carbon tetrafluoride sample gas enters the recovery pipeline through the sample inlet, the second interface of the ten-way valve, the third interface of the ten-way valve, the quantitative ring, the tenth interface of the ten-way valve, the first interface of the ten-way valve and the sample outlet finally.

[0017] When the ten-way valve is in an open state and the chromatography system is in an analysis and detection state, the carrier gas carries the carbon tetrafluoride sample gas in the quantitative ring into the detector for analysis and peak output after passing through the fourth interface of the ten-way valve, the third interface of the ten-way valve, the quantitative ring, the tenth interface of the ten-way valve, the ninth interface of the ten-way valve, the first chromatographic column, the fifth interface of the ten-way valve, the sixth interface of the ten-way valve, the second chromatographic column and the third chromatographic column.

[0018] Further, when the chromatographic system is in the initial state of analysis and detection, the paths of the carrier gas and sample gas flowing through the valve path are as follows: hydrogen passes through the second pressure stabilizing valve into the detector, air passes through the third pressure stabilizing valve into the detector; helium passes through the first pressure stabilizing valve and is divided into two paths, one of which passes through the 7th interface, the 6th interface, the second chromatographic column, the third chromatographic column of the ten-way valve into the detector, and the other of which passes through the 4th interface, the 3rd interface, the quantitative ring, the 10th interface, the 9th interface of the ten-way valve, the first chromatographic column, the 5th interface, the 6th interface of the ten-way valve, the second chromatographic column, the third chromatographic column into the detector; the sample passes through the sample inlet, the 2nd interface, the 3rd interface of the ten-way valve, the quantitative ring, the 10th interface, the 1st interface of the ten-way valve, the sample outlet and finally enters the sample recovery pipeline.

[0019] Further, when the chromatographic system is in the initial state of analysis and detection, the paths of the carrier gas and sample gas flowing through the valve path are as follows: hydrogen passes through the second pressure stabilizing valve into the detector, air passes through the third pressure stabilizing valve into the detector; helium passes through the first pressure stabilizing valve and is divided into two paths, one of which passes through the 7th interface, the 6th interface, the second chromatographic column, the third chromatographic column of the ten-way valve into the detector, and the other of which passes through the 4th interface, the 3rd interface, the quantitative ring, the 10th interface, the 9th interface of the ten-way valve, the first chromatographic column, the 5th interface, the 6th interface of the ten-way valve, the second chromatographic column, the third chromatographic column into the detector; the sample passes through the sample inlet, the 2nd interface, the 3rd interface of the ten-way valve, the quantitative ring, the 10th interface, the 1st interface of the ten-way valve, the sample outlet and finally enters the sample recovery pipeline.

[0020] Compared with the prior art, the present application has at least the following beneficial effects:

[0021] Firstly, the valve path system of the present application adopts a valve-three-column system to solve the problems of the prior art, including one ten-way valve, one quantitative ring, three chromatographic columns, one detector and two pressure stabilizing valves. The valve path system solves the problems of the prior art method, such as large operation difficulty, easy to be inaccurate, and the main component carbon tetrafluoride and the impurity component nitrogen trifluoride cannot be completely separated. The valve path system of the present application is clear, simple and convenient to operate, and accurate in analysis. The chromatographic column used in the present application has better separation ability for carbon tetrafluoride and nitrogen trifluoride, and can be effectively applied to the detection of the content of nitrogen trifluoride gas in carbon tetrafluoride.

[0022] Secondly, the detection method is optimized, which solves the problems of the prior art method, such as large operation difficulty and inaccuracy. Compared with the prior art, the present application does not need to use the valve cutting method, and the sample in the quantitative ring is all brought into the detector, and the detection result is real and reliable. (The cutting method of the prior art is to partially vent the sample in the quantitative ring. Since the retention time of carbon tetrafluoride and nitrogen trifluoride is close, nitrogen trifluoride may be partially vented, causing the test content to be low. Moreover, due to the reason of the chromatographic column, carbon tetrafluoride and nitrogen trifluoride are not well separated, which is more likely to cause inaccurate cutting and inaccurate test results.) BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0024] Figure 1 is a schematic diagram of the initial state of the valve system for gas chromatographic analysis.

[0025] Figure 2 is a schematic diagram of the analysis process of the valve system for gas chromatographic analysis.

[0026] Figure 3 is a standard gas analysis graph of carbon tetrafluoride and nitrogen trifluoride: (volume fraction CF4: 1%, NF3: 7.61 x 10 -6 );

[0027] Figure 4 is a gas analysis graph of high-purity carbon tetrafluoride: (content CF4: 99.999%);

[0028] In the figure, 1 is a ten-way valve, 2 is a sample inlet, 3 is a quantitative ring, 4 is a sample outlet, 5 is a first chromatographic column, 6 is a second chromatographic column, 7 is a third chromatographic column, 8 is a detector, 9 is a helium source, 10 is a first pressure stabilizing valve, 11 is a needle valve, 12 is a vent, 13 is a hydrogen source, 14 is a second pressure stabilizing valve, 15 is an air source, and 16 is a third pressure stabilizing valve. DETAILED DESCRIPTION

[0029] The present application will be specifically described below through exemplary embodiments. However, it should be understood that the elements, structures and features in one embodiment can also be beneficially combined into other embodiments without further description.

[0030] Example 1

[0031] The present embodiment provides a valve system for gas chromatographic analysis of nitrogen trifluoride gas in carbon tetrafluoride, which includes a ten-way valve, a quantitative ring, three chromatographic columns, a detector, and two pressure stabilizing valves. As shown in Figure 1 and Figure 2 , the initial state of the valve system for gas chromatographic analysis is shown in Figure 1 , the analysis process of the valve system for gas chromatographic analysis is shown in Figure 2 , which is used to detect the content of nitrogen trifluoride in carbon tetrafluoride. The carrier gas used by the system is high-purity helium of 99.999% or above. The flow rate and pressure of the entire carrier gas system are controlled by pressure stabilizing valves and needle valves.

[0032] The valve system of the scheme adopts one valve and three columns, the first interface and the third interface of the ten-way valve 1 are connected with the constant volume ring 3, the second interface is connected with the sample inlet 2, the fourth interface and the seventh interface are connected with the helium source 9 through the first pressure stabilizing valve 10, the fifth interface and the ninth interface are connected with the first chromatographic column 5, the eighth interface is connected with the venting port 12 through the needle valve 11, the sixth interface and the detector 8 are connected with the second chromatographic column 6 and the third chromatographic column 7, and the first interface is connected with the sample outlet 4. The detector 8 is connected with the hydrogen source 13 and the air source 15 through the second pressure stabilizing valve 14 and the third pressure stabilizing valve 16 respectively. The sample outlet 4 is connected with the external rotor flow meter and then enters the tail gas recovery pipeline.

[0033] In the scheme, the first chromatographic column 5 is selected from Hayesep Q chromatographic column with a length of 9 feet; the second chromatographic column 6 is selected from Hayesep Q chromatographic column with a length of 20 feet; and the third chromatographic column 7 is preferably Hayesep T chromatographic column with a length of 9 feet.

[0034] In the scheme, the volume of the constant volume ring 3 is 1ml.

[0035] In the embodiment, the detector 8 is selected from the flame ionization detector (FID).

[0036] The initial state before sampling is as shown in Figure 1 At this time, the hydrogen enters the detector 8 through the second pressure stabilizing valve 14, and the air enters the detector 8 through the third pressure stabilizing valve 16. The helium is divided into two paths after passing through the first pressure stabilizing valve 10, one path enters the detector 8 through the seventh interface, the eighth interface, the needle valve 11 and the venting port 12 of the ten-way valve 1, and the other path carries the carbon tetrafluoride sample in the constant volume ring 3 into the detector 8 through the fourth interface, the third interface, the constant volume ring 3, the tenth interface, the ninth interface, the first chromatographic column 5, the fifth interface, the sixth interface, the second chromatographic column 6 and the third chromatographic column 7 of the ten-way valve 1. The carbon tetrafluoride sample gas finally enters the sample recovery pipeline through the second interface, the first interface and the sample outlet 4 of the ten-way valve 1.

[0037] The sampling state is as shown in Figure 2 At this time, the hydrogen enters the detector 8 through the second pressure stabilizing valve 14, and the air enters the detector 8 through the third pressure stabilizing valve 16. The helium is divided into two paths after passing through the first pressure stabilizing valve 10, one path enters the detector 8 through the seventh interface, the eighth interface, the needle valve 11 and the venting port 12 of the ten-way valve 1, and the other path carries the carbon tetrafluoride sample in the constant volume ring 3 into the detector 8 through the fourth interface, the third interface, the constant volume ring 3, the tenth interface, the ninth interface, the first chromatographic column 5, the fifth interface, the sixth interface, the second chromatographic column 6 and the third chromatographic column 7 of the ten-way valve 1. The carbon tetrafluoride sample gas finally enters the sample recovery pipeline through the second interface, the first interface and the sample outlet 4 of the ten-way valve 1.

[0038] In this embodiment, the valve system of the present application is used to analyze a standard gas containing CF4 and NF3 (volume fraction: CF4: 1%, NF3: 7.61x10-6), and the results are as follows Figure 3 It can be seen that the CF4 and NF3 components in the standard gas are completely separated in the chromatogram Figure 2

[0039] Example 2

[0040] The present embodiment provides a valve system for gas chromatographic analysis of NF3 in CF4, which uses a valve system with three columns, including a ten-port valve, a constant volume ring, three chromatographic columns, a detector, and two pressure stabilizing valves. As shown in Figure 1 and Figure 2 is a schematic diagram of the initial state of the detection of the chromatographic analysis valve system, Figure 1 is a schematic diagram of the detection analysis of the chromatographic analysis valve system, which is used to detect the content of NF3 in CF4. The carrier gas used by the system is high-purity helium gas of 99.999% or more. The flow rate and pressure of the entire carrier gas system are controlled by pressure stabilizing valves and needle valves. Figure 2 In this scheme, the first interface and the third interface of the ten-port valve 1 are connected with the constant volume ring 3, the second interface is connected with the sample inlet 2, the fourth interface and the seventh interface are connected with the helium source 9 through the first pressure stabilizing valve 10, the fifth interface and the ninth interface are connected with the first chromatographic column 5, the eighth interface is connected with the vent 12 through the needle valve 11, the sixth interface is connected with the second chromatographic column 6 and the third chromatographic column 7, and the first interface is connected with the sample outlet 4. The detector 8 is connected with the hydrogen source 13 and the air source 15 through the second pressure stabilizing valve 14 and the third pressure stabilizing valve 16, respectively. The sample outlet is connected with an external rotor flow meter and then enters the tail gas recovery pipeline.

[0041] In this embodiment, the first chromatographic column 5 is a Hayesep Q chromatographic column with a length of 9 feet; the second chromatographic column 6 is a Hayesep Q chromatographic column with a length of 20 feet; and the third chromatographic column 7 is preferably a Hayesep T chromatographic column with a length of 9 feet.

[0042] In this embodiment, the volume of the constant volume ring 3 is 1ml.

[0043] In this embodiment, the detector 8 is a flame ionization detector (FID).

[0044] The initial state before sampling is as follows

[0045] Figure 1 ​​As shown: Hydrogen gas enters detector 8 through the second pressure regulating valve 14, and air enters detector 8 through the third pressure regulating valve 16. Helium gas is split into two paths after passing through the first pressure reducing valve 10. One path passes through the 7th and 6th ports of the 10-way valve 1, the second chromatographic column 6, and the third chromatographic column 7 before entering detector 8. The other path passes through the 4th and 5th ports of the 10-way valve 1, the first chromatographic column 5, the 9th and 8th ports of the 10-way valve 1, the needle valve 11, and the vent port 12 for venting. The carbon tetrafluoride sample passes through the sample inlet 2, the 2nd and 3rd ports of the 10-way valve 1, the quantitative loop 3, the 10th and 1st ports of the 10-way valve 1, and the sample outlet 4 before finally entering the sample recovery pipeline.

[0046] Sample preparation status during injection, such as Figure 2 As shown: Hydrogen gas enters detector 8 through the second pressure regulating valve 14, and air enters detector 8 through the third pressure regulating valve 16. Helium gas is split into two paths after passing through the first pressure regulating valve 10. One path is vented through the 7th and 8th ports of the 10-way valve 1, the needle valve 11, and the vent port 12. The other path carries the carbon tetrafluoride sample from the quantitative loop 3 into detector 8 through the 4th and 3rd ports of the 10-way valve 1, the quantitative loop 3, the 10th and 9th ports, the first chromatographic column 5, the 5th and 6th ports of the 10-way valve, the second chromatographic column 6, and the third chromatographic column 7. The carbon tetrafluoride sample gas finally enters the sample recovery line through the 2nd and 1st ports of the 10-way valve 1 and the sample outlet 4.

[0047] The valve system of this patent was used to analyze a bottle of high-purity carbon tetrafluoride gas (CF4 content: 99.999%). The chromatogram is shown below. Figure 4 .according to Figure 4 It can be seen that even if the carbon tetrafluoride content reaches the level of high-purity gas, the peak position of nitrogen trifluoride on the chromatogram can be completely separated from the peak position of the carbon tetrafluoride component without being affected. According to the external standard method, the content of nitrogen trifluoride in this bottle of high-purity carbon tetrafluoride gas is 1.97 ppm.

[0048] As can be seen from the above examples, Example 1 tested standard gases with known contents of nitrogen trifluoride and carbon tetrafluoride, while Example 2 tested high-purity carbon tetrafluoride gas with an unknown content of nitrogen trifluoride. In Example 1, the carbon tetrafluoride content was 1%, and in Example 2, the carbon tetrafluoride content was 99.999%. Examples 1 and 2 demonstrate that this method can test nitrogen trifluoride in carbon tetrafluoride of different purities, solving the problem of difficulty in analyzing nitrogen trifluoride in high-purity carbon tetrafluoride. It should be noted that the quantification of nitrogen trifluoride was performed using the external standard method; Example 1 shows the standard gas chromatogram.

[0049] Example 3

[0050] This embodiment also provides a method for using a gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride.

[0051] Step one, set valve event 0 min on gas chromatography operation software, at this time the state of ten-way valve 1 is "off", so that the carbon tetrafluoride sample gas enters the recovery pipeline;

[0052] The specific steps are as follows: when the chromatographic system is in the initial state of analysis and detection, the paths of the carrier gas and the carbon tetrafluoride sample gas flowing through the valve path are as follows: hydrogen passes through the second pressure stabilizing valve 14 to enter the detector 8, and air passes through the third pressure stabilizing valve 16 to enter the detector 8. After the helium passes through the first pressure stabilizing valve 10, it is divided into two paths, one of which passes through the seventh interface, the sixth interface, the second chromatographic column 6, and the third chromatographic column 7 of the ten-way valve 1 to enter the detector 8, and the other of which passes through the fourth interface, the fifth interface, the first chromatographic column 5, the ninth interface, the eighth interface of the ten-way valve 1, the needle valve 11, and the vent port 12 for venting. The carbon tetrafluoride sample passes through the sample inlet 2, the second interface, the third interface of the ten-way valve, the quantitative ring 3, the tenth interface, the first interface of the ten-way valve, and finally enters the sample recovery pipeline.

[0053] In step one, when the entire chromatographic system is in the initial state of analysis and detection; the ten-way valve 1 is in the closed state, so that the sample can pass through the sample inlet 2-ten-way valve second interface-third interface-enter the quantitative ring 3, and the sample to be analyzed can be introduced into the system in the state of being analyzed.

[0054] In step one, hydrogen passes through the second pressure stabilizing valve 14 to enter the detector 8, and air passes through the third pressure stabilizing valve 16 to enter the detector 8; the purpose of this is that the detector used in the present application is a flame ionization detector (FID), which requires hydrogen to enter the detector 8 as combustion gas and air as combustion-supporting gas, and these two conditions are indispensable.

[0055] In step one, after the helium passes through the first pressure stabilizing valve 10, it is divided into two paths, one of which passes through the seventh interface, the sixth interface of the ten-way valve 1, the second chromatographic column 6, and the third chromatographic column 7 to enter the detector 8, and the other of which passes through the fourth interface, the fifth interface of the ten-way valve 1, the first chromatographic column 5, the ninth interface, the eighth interface of the ten-way valve 1, the needle valve 11, and the vent port 12 for venting. Its role is to prevent water and impurities in the air from returning to the detector 8 and the chromatographic column from the detector 8 outlet, polluting the detector and the chromatographic column; the other path passes through the fourth interface, the fifth interface of the ten-way valve 1, the first chromatographic column 5, the ninth interface, the eighth interface of the ten-way valve 1, the needle valve 11, and the vent port 12 for venting. Its role is to prevent impurities in the air from entering the chromatographic column and affecting analysis.

[0056] In step one, the carbon tetrafluoride sample passes through the sample inlet 2, the second interface, the third interface of the ten-way valve 1, the quantitative ring 3, the tenth interface of the ten-way valve 1, the first interface, and finally enters the sample recovery pipeline; the role is to introduce the sample into the quantitative ring 3 and introduce the sample into the system for the next step of analysis.

[0057] Step two, set valve event 5min on gas chromatography workstation, ten-way valve is "open", carbon tetrafluoride sample gas can enter the detector to analyze the peak.

[0058] The specific steps are as follows: when the chromatographic system is in the analysis detection state, the carrier gas and the nitrogen trifluoride sample gas flow through the valve path as follows: hydrogen enters the detector 8 through the second pressure stabilizing valve 14, and air enters the detector 8 through the third pressure stabilizing valve 16. After the helium passes through the first pressure stabilizing valve 10, it is divided into two paths, one of which passes through the seventh interface and the eighth interface of the ten-way valve 1, the needle valve 11, and the vent port 12, and the other of which passes through the fourth interface and the third interface of the ten-way valve 1, the quantitative ring 3, the tenth interface, the ninth interface, the first chromatographic column 5, the fifth interface and the sixth interface of the ten-way valve, the second chromatographic column 6, and the third chromatographic column 7 to carry the carbon tetrafluoride sample in the quantitative ring 3 into the detector 8. The carbon tetrafluoride sample gas finally enters the sample recovery pipeline through the second interface and the first interface of the ten-way valve and the sample outlet 4.

[0059] In step two, when the entire chromatographic system is in the analysis detection state, the ten-way valve 1 is in the open state; the role is to carry the sample in the quantitative ring 3 into the chromatographic column by the carrier gas for component separation and then into the detector 8 for analysis.

[0060] In step two, hydrogen enters the detector 8 through the second pressure stabilizing valve 14, and air enters the detector 8 through the third pressure stabilizing valve 16; this is because the detector used in the present application is a flame ionization detector (FID), and the premise of its operation is that hydrogen enters the detector as combustion gas and air as combustion-supporting gas.

[0061] In step two, after the helium passes through the first pressure stabilizing valve 10, it is divided into two paths, one of which passes through the seventh interface and the eighth interface of the ten-way valve 1, the needle valve 11, and the vent port 12. The role is that the carrier gas cannot be stored in the pipeline for a long time, and the pressure rise will cause pipeline leakage; after the ten-way valve 1 is opened, this path can only be vented. The other path passes through the fourth interface and the third interface of the ten-way valve 1, the quantitative ring 3, the tenth interface, the ninth interface, the first chromatographic column 5, the fifth interface and the sixth interface of the ten-way valve 1, the second chromatographic column 6, and the third chromatographic column 7 to carry the carbon tetrafluoride sample in the quantitative ring 3 into the detector 8. The role is that this process is to make the carrier gas carry the carbon tetrafluoride sample in the quantitative ring 3 to flow through the chromatographic column, separate the carbon tetrafluoride and nitrogen trifluoride on the chromatographic column, and then carry them into the detector 8 for detection; the chromatographic column is used to separate the carbon tetrafluoride and nitrogen trifluoride components.

[0062] In step two, the sample gas finally enters the sample recovery pipeline through the second interface and the first interface of the ten-way valve and the sample outlet 4. The role is that after the ten-way valve 1 is switched to the open state, the sample in the quantitative ring 3 to be analyzed has been carried into the system by the carrier gas, and the excess sample can be recovered.

[0063] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above disclosed technical contents to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the technical solution of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride, characterized in that: The device includes a 10-port valve, a quantitative loop, and a detector. The first port of the 10-port valve is connected to the sample outlet, the second port is connected to the sample inlet, a quantitative loop is provided between the third and tenth ports, a first chromatographic column is provided between the fifth and ninth ports, the sixth port is connected to the detector via a second and a third chromatographic column, the eighth port is connected to the vent, the fourth and seventh ports are connected to a helium source, and the detector is connected to a hydrogen source and an air source, respectively. The first and second chromatographic columns are Hayesep Q columns, and the third chromatographic column is a Hayesep T column.

2. The gas chromatography valve system for analyzing nitrogen trifluoride gas content in carbon tetrafluoride according to claim 1, characterized in that: The fourth and seventh ports of the ten-way valve are connected to a helium source via a pressure regulating valve.

3. The gas chromatography valve system for analyzing nitrogen trifluoride gas content in carbon tetrafluoride according to claim 1, characterized in that: The detector is equipped with pressure regulating valves between itself and the hydrogen source and the air source, respectively.

4. The gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride according to any one of claims 1-3, characterized in that: A needle valve is installed between the 8th port of the ten-way valve and the vent port.

5. The gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride according to any one of claims 1-3, characterized in that: The sample outlet is connected to an external rotor flow meter and then enters the exhaust gas recovery pipeline.

6. The method of using the gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride according to claims 1-5, characterized in that: The specific steps are as follows: When the ten-way valve is closed and the chromatography system is in the initial state of analysis and detection, the carbon tetrafluoride sample gas passes through the sample inlet, the second and third ports of the ten-way valve, the metering loop, the tenth and first ports of the ten-way valve, and finally enters the recovery pipeline through the sample outlet. When the 10-way valve is open and the chromatographic system is in analytical detection mode, the carrier gas passes through the 4th and 3rd ports of the 10-way valve, the quantitative loop, the 10th and 9th ports of the 10-way valve, the first chromatographic column, the 5th and 6th ports of the 10-way valve, the second chromatographic column, and the third chromatographic column, carrying the carbon tetrafluoride sample gas in the quantitative loop into the detector for analysis and peak elution.

7. The method of using the gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride according to claim 6, characterized in that: When the chromatographic system is in the initial analytical detection state, the carrier gas and sample gas flow through the valve line as follows: Hydrogen enters the detector through the second pressure regulating valve, and air enters the detector through the third pressure regulating valve; Helium is divided into two paths after passing through the first pressure regulating valve. One path passes through the 7th and 6th ports of the 10-way valve, the second chromatographic column, and the third chromatographic column to enter the detector, while the other path passes through the 4th and 5th ports of the 10-way valve, the first chromatographic column, the 9th and 8th ports of the 10-way valve, the needle valve, and the vent port for venting. The sample enters the sample recovery line through the sample inlet, the 2nd and 3rd ports of the 10-way valve, the quantitative loop, the 10th and 1st ports of the 10-way valve, and the sample outlet.

8. The method of using the gas chromatography valve system for analyzing the content of nitrogen trifluoride gas in carbon tetrafluoride according to claim 6, characterized in that: When the chromatography system is in analytical detection mode, the carrier gas and sample gas flow through the valve lines as follows: Hydrogen enters the detector through the second pressure regulating valve, and air enters the detector through the third pressure regulating valve; Helium is divided into two paths after passing through the first pressure regulating valve. One path passes through the 7th and 8th ports of the 10-port valve, the needle valve, and the vent port for venting, while the other path passes through the 4th and 3rd ports of the 10-port valve, the quantitative loop 3, the 10th and 9th ports of the 10-port valve, the first chromatographic column, the 5th and 6th ports of the 10-port valve, the second chromatographic column, and the third chromatographic column to carry the sample in the quantitative loop into the detector; The sample gas finally enters the sample recovery line through the 2nd port, the 1st port, and the sample outlet on the 10-port valve.

Images