Device and method for detecting components of high-pressure gas

Abstract

The invention provides a device and a method for detecting components of high-pressure gas. The device comprises a test interface, a mass flow controller, a stop valve, a split-flow sample injection pipe, a differential sample injection pipe valve, a gas analysis device and a vacuum pump, an inlet of the mass flow controller is connected with the test interface, and an outlet of the mass flow controller is connected with an inlet of the stop valve; a split-flow sample injection pipe is communicated between an outlet of the mass flow controller and an inlet of the stop valve, an outlet of the stop valve is connected with an inlet of the gas analysis device, and the vacuum pump is connected with the gas analysis device; the vacuum pump is connected with one end of the differential sample injection pipe, the other end of the differential sample injection pipe is connected with an outlet of the stop valve and an inlet of the gas analysis device, the split-flow sample injection pipe and the differential sample injection pipe are sequentially arranged between the test interface and the gas analysis device, flow limiting through a pipeline is not needed through a miniaturized multi-channel differential design, the response speed is second-level, and the detection accuracy is high. No additional vacuum pump is needed, cost is controllable, complex logic judgment is not needed, and reliability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical instruments, and in particular to a device and method for detecting high-pressure gas components. Background Art

[0002] There are many types of devices for high-pressure gas component detection, and gas analysis devices include spectroscopy, mass spectrometry, and chromatography. Because the substances to be monitored contain non-polar molecules, infrared spectroscopy cannot be tested. Because the analysis time of chromatography is in the order of minutes, it cannot meet the needs of real-time online monitoring. The mass spectrometer has requirements for vacuum during operation. The conventional design is to introduce the sample through a stainless steel capillary or quartz capillary injection device. The capillary is usually longer than 1 meter and plays a role in limiting the flow to maintain the vacuum of the mass spectrometer operation. Under this design condition, since the gas exchange time in the capillary is usually more than half an hour, real-time monitoring cannot be achieved. Another conventional design is to use a flow-limiting orifice injection to maintain the working conditions of the mass spectrometer. This design can achieve the purpose of real-time monitoring, but when the vacuum of the test chamber is higher than 10Torr, the aperture of the flow-limiting orifice is less than 20μm, the mechanical processing is difficult, and the accuracy cannot be controlled, resulting in high prices and poor stability. At the same time, small-sized flow-limiting orifices are easily blocked by particulate matter. In order to solve this problem, existing equipment also has a solution of adding a flow-limiting capillary. When the semiconductor process exhaust gas treatment equipment operates normally, the treatment efficiency of different substances is relatively stable. Through real-time online monitoring of the inlet and outlet substance concentrations of the semiconductor process exhaust gas treatment equipment, it can effectively reflect whether the semiconductor process exhaust gas treatment equipment is operating normally and whether the manufacturing process is operating normally. Therefore, the monitoring equipment needs to achieve a second-level response. The monitored substances include SF6, H2, CCl4, F2, HF, Cl2 and other substances. The exhaust gas inlet and outlet pressures are slightly less than 1 atmosphere. In addition, due to the large difference in the inlet and outlet concentrations of the exhaust gas treatment equipment, conventional mass spectrometers cannot directly perform quantitative tests on the inlet and outlet concentrations. After testing the inlet concentration, the pipeline needs to be cleaned and then the outlet concentration test is performed.

[0003] The patent document with the publication number CN115060782A discloses a residual gas analysis device and method for semiconductor industrial tail gas. It includes a pressure-stabilizing tank, on which are connected the first vacuum gauge and the second vacuum gauge, and a pressure gauge; the first vacuum gauge and the second vacuum gauge are used to measure the vacuum degree in the pressure-stabilizing tank; one end of the pressure-stabilizing tank is connected to the output end of the manual valve through the first flowmeter and the first solenoid valve in parallel, and the input end of the manual valve is connected to the outlet of the tail gas collection equipment of the semiconductor production line; the other end of the pressure-stabilizing tank is connected to the measuring chamber through multiple parallel channels; the measuring chamber is connected to the third vacuum gauge and the mass spectrometer; the third vacuum gauge is used to detect the vacuum degree of the measuring chamber; the measuring chamber is also connected to the molecular pump through the fourth solenoid valve, and the molecular pump is also connected to the front pump. Quantitative detection of residual gas in semiconductor industrial tail gas under a wide pressure range is achieved. This patent uses a solenoid valve for flow conductance restriction, and multiple logical judgments are required during use to ensure the application of residual gas analysis, and the process is too complicated.

[0004] The patent document with publication number US20240019336A1 discloses a gas leak detection device. The device includes a connector, a vacuum pump, a gas detector and a gas pressure sensor. By combining the functions of the gas detector and the gas pressure sensor, the integration of overall and local leak detection is achieved, and the efficiency and accuracy of detection are improved. During overall leak detection, test gas is added to the test object, the test object is connected to the gas detection device through a connector, and is evacuated by a vacuum pump. The gas detector detects overall leaks by detecting leaked test gas. The spraying principle is used for local leak detection, by spraying the test gas to the outside of the test object, and the test object is evacuated by a vacuum pump. The gas detector locates local leaks by detecting leaked test gas.

[0005] The patent document with publication number US2009277250A1 discloses a sniffing detector device. The device includes a main device, a vacuum pump device and a gas detector, and a flexible sniffing hose is connected to the system for the sniffing probe. The hose performs a certain flow limiting operation. A filter and a flow limiting device are installed downstream of the hose to ensure that when the air pressure is too high, there will be no excessive impact on the molecular pump. In order to maintain the vacuum degree at the gas detector, the gas passes through the flow limiting device and is simultaneously connected to the gas detector, the molecular pump inlet, and the connection between the two-stage front pump.

[0006] The above two patents use capillaries or flexible hoses to limit flow, or increase the number of front-stage pumps to maintain the operating vacuum of the gas detector, which has the problems of long response time or complex structure and high cost. Summary of the invention

[0007] In view of the defects in the prior art, an object of the present invention is to provide a device and method for detecting high-pressure gas components.

[0008] The device for high-pressure gas component detection provided by the present invention comprises a test interface, a mass flow controller, a stop valve, a split injection tube, a differential injection tube valve, a gas analysis device and a vacuum pump;

[0009] The inlet of the mass flow controller is connected to the external test system through the test interface, and the outlet of the mass flow controller is connected to the inlet of the stop valve;

[0010] A split flow injection tube is connected between the outlet of the mass flow controller and the inlet of the stop valve, and the split flow injection tube is used to discharge the gas that does not pass through the stop valve to the outside of the system. The outlet of the stop valve is connected to the inlet of the gas analysis device, and the vacuum pump is connected to the gas analysis device;

[0011] The vacuum pump is connected to one end of a differential injection tube, the other end of the differential injection tube is connected to the outlet of the stop valve and the inlet of the gas analysis device, and a differential injection tube valve is arranged on the differential injection tube.

[0012] Preferably, the vacuum pump comprises a molecular pump and a fore pump;

[0013] The front stage pump is arranged downstream of the molecular pump and is used for vacuuming. The molecular pump is connected to the gas analysis device and the differential injection tube valve respectively.

[0014] Preferably, the test interface includes a KF interface, a CF interface, a VCR interface or a card sleeve interface.

[0015] Preferably, the pressure at the split flow inlet tube is lower than the pressure at the test interface.

[0016] Preferably, the stop valve is a pneumatic valve, an electric valve or a manual valve, and the stop valve is used to control whether the gas to be tested is introduced into the gas analysis device;

[0017] The differential injection tube valve is a pneumatic valve, an electric valve or a manual valve, and the differential injection tube valve is used to control the on-off of the differential injection tube.

[0018] Preferably, a differential interface is provided on the vacuum pump, and one end of the differential injection tube is connected via the differential interface.

[0019] Preferably, the test interface includes a first test interface and a third test interface, and the mass flow controller includes a first mass flow controller and a third mass flow controller;

[0020] The inlet of the first mass flow controller is connected to the air outlet of the external exhaust gas treatment device through the first test interface, and the inlet of the third mass flow controller is connected to the air inlet of the external exhaust gas treatment device through the third test interface.

[0021] Preferably, it further comprises a second test interface, a second mass flow controller, a first gas circuit control valve and a second gas circuit control valve, wherein the inlet of the second mass flow controller is connected to an external nitrogen gas source through the second test interface;

[0022] A second air inlet pipeline is provided between the second test interface and the second mass flow controller, a first air inlet pipeline is provided between the first test interface and the first mass flow controller, and a third air inlet pipeline is provided between the third test interface and the third mass flow controller;

[0023] The first air circuit control valve is used to connect the second air intake pipeline with the first air intake pipeline, and the second air circuit control valve is used to connect the second air intake pipeline with the third air intake pipeline.

[0024] According to the method for high-pressure gas component detection provided by the present invention, the device for high-pressure gas component detection is used, and the method comprises the following steps:

[0025] Turn on the vacuum pump, and the gas to be tested enters the mass flow controller after passing through the test interface, and then enters the split injection area according to the preset flow rate. The stop valve is opened, and part of the gas to be tested is discharged through the split injection tube. The remaining part of the gas to be tested passes through the stop valve and is divided into the first part and the second part;

[0026] The first part of the gas to be tested enters the gas analysis device through the flow limiting device for detection, and the second part of the gas to be tested is directly extracted by the vacuum pump through the differential injection tube valve.

[0027] Preferably, the method further comprises the following steps:

[0028] Inlet gas testing steps: open the second mass flow controller and the third mass flow controller at the same time, dilute the inlet gas with nitrogen according to a preset ratio, and the diluted gas enters the gas analysis device for detection;

[0029] After the detection is completed, the second mass flow controller is closed, the second gas path control valve is opened, and nitrogen purge is performed. After the purge is completed, the second gas path control valve and the third flow controller are closed;

[0030] Gas outlet gas testing steps: open the second mass flow controller and the first mass flow controller at the same time, dilute the gas at the outlet with nitrogen according to a preset ratio, and the diluted gas enters the gas analysis device for detection;

[0031] After the detection is completed, the second mass flow controller is closed, the first gas path control valve is opened, and nitrogen purge is performed. After the purge is completed, the first gas path control valve and the first flow controller are closed.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention has a simple structure and is easy to operate. It adopts a technical means of sequentially arranging a split flow injection tube and a differential injection tube between the test interface and the gas analysis device. Through a miniaturized multi-channel differential design, the flow of the test gas is limited step by step. There is no need to use pipelines to limit the flow. The response speed is in seconds, and there is no need to add a vacuum pump. The cost is controllable, no complex logical judgment is required, and the reliability is high.

[0034] 2. The present invention adopts the technical means of connecting the air inlet and the air outlet to two test interfaces respectively, and adopts the technical means of external nitrogen gas source, which can directly perform quantitative testing of inlet and outlet concentrations, and can meet the actual needs of cleaning the pipeline after testing the inlet concentration and then testing the outlet concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0036] Figure 1 It is a schematic diagram of the overall structure of Example 1;

[0037] Figure 2 It is a schematic diagram of the overall structure of Example 2;

[0038] Figure 3 This is a schematic diagram of the measured results of gas outlet monitoring in Example 2.

[0039] The figure shows:

[0040] Split injection tube 13 First mass flow controller 22

[0041] Stop valve 14 Second test interface 23

[0042] Differential injection tube valve 15 Second mass flow controller 24

[0043] Gas analysis device 16 Third test interface 25

[0044] Molecular pump 17 Third mass flow controller 26

[0045] Fore pump 18 First gas line control valve 27

[0046] First test interface 21 Second gas path control valve 28 DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0048] The present invention discloses a device and method for high-pressure gas component detection. By sequentially arranging a split flow injection tube and a differential injection tube between a test interface and a gas analysis device, a miniaturized multi-channel differential design is realized. There is no need to use pipeline current limiting, the response speed is in seconds, no need to add a vacuum pump, the cost is controllable, no complex logical judgment is required, and the reliability is high.

[0049] According to the device for high-pressure gas component detection provided by the present invention, it includes a test interface, a mass flow controller, a stop valve 14, a shunt injection tube 13, a differential injection tube valve 15, a gas analysis device 16 and a vacuum pump; the inlet of the mass flow controller is connected to the external test system through the test interface, and the outlet of the mass flow controller is connected to the inlet of the stop valve 14; the shunt injection tube 13 is connected between the outlet of the mass flow controller and the inlet of the stop valve 14, the outlet of the stop valve 14 is connected to the inlet of the gas analysis device 16, and the vacuum pump is connected to the gas analysis device 16; the vacuum pump is connected to one end of the differential injection tube, the other end of the differential injection tube is connected to the outlet of the stop valve 14 and the inlet of the gas analysis device 16, and the differential injection tube is provided with a differential injection tube valve 15.

[0050] Preferably, the test interface is of KF16, KF25, KF40, CF35, 1 / 4" VCR, 1 / 4" ferrule and other standards. The purpose of the mass flow controller is to initially limit the gas injection volume, determine the system injection volume, and ensure the accuracy of quantification. The mass flow controller is set to 4L / min. The pressure at the split injection tube 13 is lower than the pressure at the test interface. The stop valve 14 is a pneumatic valve, an electric valve or a manual valve, which controls whether the gas to be tested is introduced into the gas analysis device. The flow rate of the stop valve 14 is 1-2sccm. The differential injection tube valve 15 is a pneumatic valve, an electric valve or a manual valve, which controls the on and off of the differential injection tube. The gas analysis device 16 is a mass spectrometer. There is a flow limiting device at the inlet of the gas analysis device 16, and the flow rate is <1sccm. The fore pump 18 is a rotary pump or a diaphragm pump, and the pumping speed is 15~50L / min. The pumping speed of the molecular pump 17 is 70~90L / s. The molecular pump 17 has a differential interface, specifically a G1 / 8 internal thread interface is opened on the housing of the molecular pump 17. The mass flow controller, the stop valve 14, and the differential injection tube valve 15 are corrosion-resistant. The bearings of the molecular pump 17 are purged with clean nitrogen. The material of the differential injection tube is 316L stainless steel or polytetrafluoroethylene.

[0051] Example 1

[0052] This embodiment is a preferred embodiment of the above embodiments. Figure 1 As shown, it is a structural schematic diagram of a device for high-pressure gas component detection involved in this embodiment. It includes a first test interface 21, a first mass flow controller 22, a stop valve 14, a split injection tube 13, a differential injection tube valve 15, a gas analysis device 16, a molecular pump 17, and a pre-stage pump 18. The first test interface 21 is connected to the system to be tested, and the gas to be tested passes through the first mass flow controller 22 and enters the split injection area according to the set flow rate. The first mass flow controller 22 is set to 4L / min. The stop valve 14 controls whether the gas to be tested enters the subsequent detection equipment. When the stop valve 14 is closed, the gas to be tested is discharged through the split injection tube 13. When the stop valve 14 is opened, a small amount of the gas to be tested passes through the stop valve 14, and most of the gas is discharged through the split injection tube 13. The gas flow through the stop valve 14 is related to the pumping speed of the molecular pump 17 and the size of the current limiting device before the gas analysis device 16, which is generally 1-2sccm.

[0053] When the equipment is running, the front pump 18 starts to run, and when the vacuum degree of the gas analysis device 16 is less than or equal to 200Pa, the molecular pump 17 is automatically turned on. A G1 / 8 threaded interface is opened on the molecular pump housing, which is connected to the differential injection tube valve 15 through a 1 / 8-inch 316L stainless steel capillary. The differential injection tube valve 15 is connected to the outlet of the stop valve 14 and the inlet of the gas analysis device 16 through a 1 / 8-inch 316L stainless steel capillary, forming a T-channel gas path. A flow limiting device is provided at the air inlet of the gas analysis device 16, and the gas flow rate is less than 1sccm. Part of the gas to be tested flowing out of the stop valve 14 enters the gas analysis device 16 for monitoring through the flow limiting device, and the remaining part is directly extracted by the molecular pump 17 through the differential injection tube valve 15. The differential function of the molecular pump 17 is different from that of a conventional differential pump. The differential pump has two sets of turbine blades, and the molecular pump selected in the present invention has only one set of turbine blades, which is smaller in size and simpler in structure. If the target gas to be tested is corrosive, the downstream of the split injection tube 13 and the front pump 18 needs to be connected to a specific exhaust emission area for treatment or dilution before discharge. The molecular pump 17 needs to use nitrogen to purge the bearing. The first test interface 21 is made of 316L stainless steel. The split injection tube 13 is made of 316L stainless steel or corrosion-resistant PTFE; the first mass flow controller 22, the stop valve 14 and the differential injection tube valve 15 are corrosion-resistant valve bodies.

[0054] Example 2

[0055] This embodiment is a preferred embodiment of the above embodiments. Figure 2As shown, it is a schematic diagram of the application of a device for high-pressure gas component detection involved in this embodiment on a semiconductor tail gas treatment device. The tail gas treatment device air inlet is connected to the third test interface 25, the air outlet is connected to the first test interface 21, and the nitrogen gas source is connected to the second test interface 23. The first gas circuit control valve 27 controls the nitrogen cleaning of the pipeline where the first test interface 21 is located. The second gas circuit control valve 28 controls the nitrogen cleaning of the pipeline where the third test interface 25 is located. By setting the parameters of the second mass flow controller 24 and the third mass flow controller 26, the gas concentration at the air inlet of the tail gas treatment device can be diluted. When testing the gas components at the air inlet of the tail gas treatment device, the second mass flow controller 24 and the third mass flow controller 26 are opened at the same time, and the gas dilution is performed according to a certain ratio. The flow setting value of the second mass flow controller 24 is 100 to 1000 times the setting value of the third mass flow controller 26. The sum of the flow setting value of the second mass flow controller 24 and the setting value of the third mass flow controller 26 is 4L / min. After the test of the gas components at the inlet of the exhaust treatment device is completed, the second mass flow controller 24 is closed, and the gas circuit control valve 28 is opened for nitrogen purge. After the purge is completed, the second gas circuit control valve 28 and the third mass flow controller 26 are closed. When testing the gas components at the outlet of the exhaust treatment device, the first gas circuit control valve 27 and the second gas circuit control valve 28 are closed, and the second mass flow controller 24 and the third mass flow controller 26 are closed. The operation steps are consistent with those in Example 1. After the test is completed, the first gas circuit control valve 27 is opened for nitrogen purge. After the purge is completed, the first gas circuit control valve 27 and the first mass flow controller 22 are closed.

[0056] like Figure 3 The figure shows the actual measurement results of the device of this embodiment for monitoring the gas outlet of semiconductor tail gas treatment equipment. The substance monitored in the figure is SF6. Through the single ion monitoring mode, m / z31 is monitored in real time. By adjusting the inlet gas flow and concentration of the tail gas treatment system, the response speed of the device of the present invention is tested. The software for monitoring semiconductor process tail gas treatment equipment proposed by the present invention can display up to 100 Figure 3 The results of the example are used to conduct simultaneous real-time online monitoring of multiple substances. At the same time, according to the concentration test of the inlet and outlet gases, the processing efficiency can be automatically calculated by the software. By setting the threshold of normal processing efficiency and the threshold of inlet gas concentration, when the processing efficiency exceeds the threshold, it means that there is an abnormality or failure in the tail gas treatment device. When the inlet gas concentration exceeds the threshold, it means that there is an abnormality or failure in the upstream process equipment or process.

[0057] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0058] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A device for detecting high-pressure gas components, characterized in that: It comprises a test interface, a mass flow controller, a stop valve (14), a split injection tube (13), a differential injection tube valve (15), a gas analysis device (16) and a vacuum pump; The inlet of the mass flow controller is connected to an external test system through the test interface, and the outlet of the mass flow controller is connected to the inlet of the stop valve (14); A split flow injection tube (13) is connected between the outlet of the mass flow controller and the inlet of the stop valve (14), and the split flow injection tube (13) is used to discharge the gas that does not pass through the stop valve (14) to the outside of the system. The outlet of the stop valve (14) is connected to the inlet of a gas analysis device (16), and the vacuum pump is connected to the gas analysis device (16); The vacuum pump is connected to one end of a differential injection tube, the other end of the differential injection tube is connected to the outlet of a stop valve (14) and the inlet of a gas analysis device (16), and a differential injection tube valve (15) is provided on the differential injection tube.

2. The device for detecting high-pressure gas components according to claim 1, characterized in that: The vacuum pump comprises a molecular pump (17) and a fore pump (18); The fore pump (18) is arranged downstream of the molecular pump (17) for evacuating the air. The molecular pump (17) is respectively connected to the gas analysis device (16) and the differential injection tube valve (15).

3. The device for high-pressure gas component detection according to claim 1, characterized in that: The test interface includes a KF interface, a CF interface, a VCR interface or a card sleeve interface.

4. The device for high-pressure gas component detection according to claim 1, characterized in that: The pressure at the split flow injection tube (13) is lower than the pressure at the test interface.

5. The device for detecting high-pressure gas components according to claim 1, characterized in that: The stop valve (14) is a pneumatic valve, an electric valve or a manual valve, and the stop valve (14) is used to control whether the gas to be tested is introduced into the gas analysis device (16); The differential injection tube valve (15) is a pneumatic valve, an electric valve or a manual valve, and the differential injection tube valve (15) is used to control the on and off of the differential injection tube.

6. The device for detecting high-pressure gas components according to claim 1, characterized in that: The vacuum pump is provided with a differential interface, and is connected to one end of the differential injection tube via the differential interface.

7. The device for high-pressure gas component detection according to claim 1, characterized in that: The test interface comprises a first test interface (21) and a third test interface (25), and the mass flow controller comprises a first mass flow controller (22) and a third mass flow controller (26); The inlet of the first mass flow controller (22) is connected to the air outlet of the external exhaust gas treatment device through the first test interface (21), and the inlet of the third mass flow controller (26) is connected to the air inlet of the external exhaust gas treatment device through the third test interface (25).

8. The device for detecting high-pressure gas components according to claim 7, characterized in that: It also includes a second test interface (23), a second mass flow controller (24), a first gas circuit control valve (27) and a second gas circuit control valve (28), wherein the inlet of the second mass flow controller (24) is connected to an external nitrogen gas source through the second test interface (23); A second air intake pipeline is provided between the second test interface (23) and the second mass flow controller (24), a first air intake pipeline is provided between the first test interface (21) and the first mass flow controller (22), and a third air intake pipeline is provided between the third test interface (25) and the third mass flow controller (26); The first air circuit control valve (27) is used to connect the second air intake pipeline with the first air intake pipeline, and the second air circuit control valve (28) is used to connect the second air intake pipeline with the third air intake pipeline.

9. A method for detecting high-pressure gas components, characterized in that: The device for detecting high-pressure gas components according to any one of claims 1 to 8 comprises the following steps: The vacuum pump is turned on, and the gas to be tested enters the mass flow controller after passing through the test interface, and then enters the split injection area according to a preset flow rate. The stop valve (14) is opened, and part of the gas to be tested is discharged through the split injection tube (13), and the remaining part of the gas to be tested passes through the stop valve (14) and is divided into a first part and a second part; The first part of the gas to be tested enters the gas analysis device (16) through the flow limiting device for detection, and the second part of the gas to be tested is directly extracted by the vacuum pump through the differential injection tube valve (15).

10. The method for high-pressure gas component detection according to claim 9, characterized in that: The following steps are also included: Inlet gas testing step: simultaneously opening the second mass flow controller (24) and the third mass flow controller (26), diluting the inlet gas with nitrogen according to a preset ratio, and allowing the diluted gas to enter the gas analysis device (16) for detection; After the detection is completed, the second mass flow controller (24) is closed, the second gas path control valve (28) is opened, and nitrogen purge is performed. After the purge is completed, the second gas path control valve (28) and the third flow controller (26) are closed; Gas outlet gas testing step: simultaneously opening the second mass flow controller (24) and the first mass flow controller (22), diluting the gas outlet gas with nitrogen according to a preset ratio, and allowing the diluted gas to enter the gas analysis device (16) for detection; After the detection is completed, the second mass flow controller (24) is closed, the first gas path control valve (27) is opened, and nitrogen purge is performed. After the purge is completed, the first gas path control valve (27) and the first flow controller (22) are closed.

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