Trace SF6 gas sampler without memory effect

Abstract

The invention belongs to the field of occupational health detection, and provides a trace SF6 gas sampler without a memory effect, which comprises a sample introduction unit, a constant pressure control unit, a six-way valve 5, a quantitative sampling ring 6, a sample introduction analysis system and a flow channel cleaning system, the sampling unit is sequentially connected with the six-way valve 5 and the quantitative sampling ring 6, and the constant pressure control unit is arranged on a pipeline between the sampling unit and the six-way valve 5; and the six-way valve 5 is also respectively connected with a sample introduction analysis system, a flow channel cleaning system, a sample introduction pipeline and a sample discharge pipeline. According to the invention, cross contamination-free and long-term stable sampling of trace gas is realized. Through the design of the process, the flow channel, key equipment and the like, the possibility of cross contamination of sample gas is fundamentally eradicated, and the sampling stability and reliability are ensured by adopting a constant-pressure control system and a flow channel cleaning system, so that a reliable technical guarantee is provided for accurate collection of trace gas.

Description

Technical Field

[0001] This invention belongs to the field of occupational health testing and relates to a trace SF6 gas sampler with no memory effect. Specifically, it is a device and method for sampling trace amounts of sulfur hexafluoride gas and its decomposition products in the ambient air surrounding SF6 filling equipment. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] With the continuous development and improvement of ultra-high voltage power transmission networks, the performance requirements for power equipment using sulfur hexafluoride (SF6) as an insulating and arc-quenching medium have also increased to ensure the safety and stability of the equipment. At the same time, higher performance standards have been imposed on the supporting SF6 gas recovery, treatment, and detection equipment.

[0004] Therefore, when a minor leak occurs in sulfur hexafluoride (SF6)-filled electrical equipment, the amount of SF6 gas and its decomposition products leaking from the surrounding environment is extremely small, often at the trace level. This trace-level leakage makes samples obtained using traditional sampling methods unrepresentative, severely affecting the accuracy and reliability of the test results. This has become one of the major technical bottlenecks in the current detection of SF6 gas and its decomposition products in the ambient air surrounding SF6-filled electrical equipment.

[0005] Currently, the traditional sampling methods widely used in the field of SF6 gas detection mainly include direct sampling, gas bag sampling, and syringe sampling. However, these methods are difficult to achieve high-fidelity and stable collection of trace amounts of SF6 gas. First, during the sampling process, inaccurate pressure regulation often leads to fluctuations in gas flow rate, resulting in the loss of sample representativeness and failing to meet the high requirements of modern analytical instruments for sample introduction stability. Second, traditional sampling methods often cause changes in gas composition. For example, the target gas is easily partially adsorbed and retained during the sampling process, and components undergo cross-mixing during adsorption and desorption. Especially under low concentration conditions, the cross-mixing effect of adsorption and desorption is more significant, causing the actual sample gas composition to deviate from the true situation and introducing test errors. At the same time, impurities such as residual air in the gas bag or syringe, and the original sample gas can easily mix into the new sample during sampling, further interfering with subsequent analysis and seriously affecting the qualitative and quantitative analysis of trace SF6 decomposition products. Summary of the Invention

[0006] To address the shortcomings of traditional sampling methods, this invention provides a memory-free trace SF6 gas sampler, achieving cross-contamination-free and long-term stable sampling of trace gases. Through the design of processes, flow channels, and key equipment, this invention fundamentally eliminates the possibility of gas cross-contamination. A constant pressure control system and flow channel cleaning system ensure the stability and reliability of sampling, thus providing a reliable technical guarantee for the accurate collection of trace gases.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a trace SF6 gas sampler with no memory effect, comprising: a sample introduction unit, a constant pressure control unit, a six-way valve 5, a quantitative sampling loop 6, a gas pipeline, and a control valve.

[0008] The sample introduction unit includes at least one pump 2 and a sample introduction pipeline, with the inlet end of the pump 2 connected to the sample inlet 1. The pump 2 draws up the sample under suction, simultaneously providing power for the sample gas to pass through a six-way valve 5 and a quantitative sampling ring 6 in sequence. A constant pressure control unit is installed on the pipeline between the injection unit and the six-way valve 5. The constant pressure control unit consists of a pressure regulating valve and a buffer tank. The pressure regulating valve can ensure the stability of the injection pressure, and the buffer tank can absorb pressure pulsations by utilizing its huge gas capacity, so as to achieve precise pressure stabilization of the entire system. The six-way valve 5 is a precision fluid control valve with six fluid channel ports, which can be connected to the sample analysis system, the flow channel cleaning system, the sample inlet pipeline, and the sample outlet pipeline, respectively. The six-way valve 5 includes six ports: I, II, III, IV, V, and VI. The quantitative sampling loop 6 is a section of tubing with a precise, fixed volume to ensure consistency in the volume of each injection. The quantitative sampling loop 6 can be equipped with an external heating device 19 for heating the loop during the cleaning phase. The gas pipeline is made of 316L stainless steel and is used to connect the various components of the sampler, providing a path for gas flow. The control valve is used to open and close the gas flow, controlling the gas direction according to the actual process.

[0009] The sampler of this invention achieves cross-contamination-free collection and long-term stable sampling of trace SF6 gas by integrating a flow channel cleaning system with a constant pressure control system centered on a buffer tank.

[0010] A second aspect of the present invention provides a method for sampling using the aforementioned memoryless trace SF6 gas sampler, such as... Figure 1 As shown, it includes: Under the suction action of pump 2, the SF6 sample gas passes through the inlet 1, pressure regulating valve 3 and six-way valve inlet valve 10, and then enters the first port I of six-way valve 5; In the sampling state, the internal flow path of the six-way valve 5 is open, allowing the gas to flow sequentially through the first port I, the second port II, the quantitative sampling ring 6, and the fifth port V, and finally be discharged from the sixth port VI through the six-way valve outlet valve 11 and the sample outlet 7. Meanwhile, another stream of gas passes through the front valve 9 of the buffer tank, the buffer tank 4, and the rear valve 8 of the buffer tank, and is discharged from the outlet 7. After the quantitative sampling loop 6 is filled, close the pressure regulating valve 3 and the six-way valve outlet valve 11 to connect the quantitative sampling loop 6 with the buffer tank 4 and obtain a gas sample with stable pressure.

[0011] A third aspect of the present invention provides a method for flow channel cleaning using the aforementioned memory-free trace SF6 gas sampler, such as... Figure 2 As shown, it includes: In the cleaning state, the sample inlet valve 14 and sample outlet valve 17 are closed, and the sample bypass valve 18 is open. High-purity cleaning gas is introduced into the six-way valve 5. The internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, so that the high-purity cleaning gas flows sequentially through the cleaning gas forward blow inlet valve 12, the third port III of the six-way valve 5, the second port II, the quantitative sampling ring 6, and the fifth port V, and finally exits from the fourth port IV through the cleaning gas forward blow outlet valve 16, realizing the same-direction purging of the quantitative sampling ring 6.

[0012] Alternatively, reverse purging can be performed, with the internal flow path of the six-way valve 5 kept consistent with the sample injection analysis state, allowing the high-purity cleaning gas to flow sequentially through the cleaning gas backflush inlet valve 15, the fourth port IV and the fifth port V of the six-way valve 5, the quantitative sampling ring 6, and the second port II, and finally discharged from the third port III through the cleaning gas backflush outlet valve 13, thus achieving reverse purging of the quantitative sampling ring 6.

[0013] Beneficial effects of the present invention (1) Significantly improved sampling precision and analysis accuracy.

[0014] Traditional sampling devices often suffer from inaccurate pressure regulation and flow rate fluctuations, leading to inconsistent injection volumes and sample distortion, directly impacting the accuracy of analytical results. This invention addresses this issue by implementing a constant pressure control system centered on a buffer tank. After the quantitative sampling loop is filled with sample, it is connected to the buffer tank. Utilizing the large gas capacity of the buffer tank, any minute pressure fluctuations in the system are effectively absorbed, achieving long-term high stability of the sampling pressure. This fundamentally ensures a constant volume and consistent pressure of sample gas entering the quantitative sampling loop each time, eliminating analytical errors caused by injection volume distortion and significantly improving the accuracy and repeatability of trace component analysis.

[0015] (2) The memory effect has been completely eliminated, ensuring the authenticity and reliability of the sample.

[0016] Traditional methods often suffer from unavoidable gas cross-contamination and memory effects, which are key reasons for biases and even errors in analytical results. These include the adsorption and retention of the target gas in the pipeline, cross-mixing of adsorption and desorption between samples, and the introduction of environmental impurities. This invention designs a flow channel cleaning system that, through a six-way valve, can perform bidirectional flushing of the quantitative sampling loop and pipeline. Forward flushing removes residues in the main flow path, while backflushing effectively removes and purges trace amounts of residual gas adsorbed in "dead zones" such as pipelines, valves, and the inner wall of the quantitative sampling loop. This bidirectional, dead-zone-free cleaning method fundamentally eliminates cross-contamination between samples, ensuring that the collected trace SF6 gas composition is highly consistent with the actual situation, thus providing a fundamental guarantee for the reliability of the analytical results.

[0017] (3) Long-term stable sampling has been achieved, which has improved the overall analysis efficiency and system reliability.

[0018] This invention organically combines constant pressure control and flow path cleaning, enabling fully automated control of the entire process. This not only solves the accuracy problem of single sampling but also ensures data stability and consistency during continuous multiple sampling or long-term online monitoring. Because the system has self-cleaning capabilities, it reduces the need for frequent maintenance and calibration due to contamination, improving overall analytical efficiency and long-term system reliability, and providing highly reliable sample introduction assurance for modern high-precision analytical instruments.

[0019] (4) The device of the present invention has a simple structure, strong practicality, and is easy to promote. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. Exemplary embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a schematic diagram of the structure of the present invention under sampling and voltage stabilization conditions.

[0022] Figure 2 This is a schematic diagram of the structure of the present invention under the conditions of sample injection analysis and flow path cleaning.

[0023] In the figure: (1) - Inlet; (2) - Pump; (3) - Pressure regulating valve; (4) - Buffer tank; (5) - Six-way valve; (6) - Quantitative sampling loop; (7) - Outlet; (8) - Buffer tank rear valve; (9) - Buffer tank front valve; (10) - Six-way valve inlet valve; (11) - Six-way valve outlet valve; (12) - Cleaning gas forward blow inlet valve; (13) - Cleaning gas back blow outlet valve; (14) - Inlet valve; (15) - Cleaning gas back blow inlet valve; (16) - Cleaning gas forward blow outlet valve; (17) - Inlet outlet valve; (18) - Inlet bypass valve; (19) - Heating device. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods in the art or product instructions. Similarly, unless otherwise specified, the test methods of this invention are performed in accordance with conventional methods in the art or industry-standard methods or practices. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0026] This invention provides a trace SF6 gas sampler without memory effect, comprising: a sample introduction unit, a constant pressure control unit, a six-way valve 5, a quantitative sampling loop 6, a sample introduction and analysis system, and a flow channel cleaning system; The sample introduction unit includes a pump 2 and a sample introduction pipeline, with the inlet end of the pump 2 connected to the sample inlet 1. The pump 2 draws up the sample under suction, simultaneously providing power for the sample gas to pass through a six-way valve 5 and a quantitative sampling ring 6 in sequence. A constant pressure control unit is installed on the pipeline between the injection unit and the six-way valve 5. The constant pressure control unit consists of a pressure regulating valve and a buffer tank. The pressure regulating valve can ensure the stability of the injection pressure, and the buffer tank can absorb pressure pulsations by utilizing its huge gas capacity, so as to achieve precise pressure stabilization of the entire system. The six-way valve 5 is a precision fluid control valve with six fluid channel ports, which can be connected to the sample analysis system, the flow channel cleaning system, the sample inlet pipeline, and the sample outlet pipeline, respectively. The six-way valve 5 includes six ports: I, II, III, IV, V, and VI. The quantitative sampling loop 6 is a section of tubing with a precise, fixed volume to ensure consistency in the volume of each injection. The quantitative sampling loop 6 can be equipped with an external heating device 19 for heating the loop during the cleaning phase. The sample injection analysis system and the flow channel cleaning system are achieved by switching between different control valves.

[0027] This invention offers the following advantages: First, it solves the problem of flow rate fluctuations caused by inaccurate pressure regulation in traditional sampling devices. A constant pressure control system ensures long-term stability of the sampling pressure, guaranteeing accurate and distortion-free sample volume for each injection. Second, it eliminates gas composition changes during sampling, including issues such as target gas adsorption and retention, cross-mixing of adsorption and desorption, and contamination by environmental impurities. A flow channel cleaning system fundamentally eliminates the possibility of cross-contamination, ensuring that the sampled gas composition is highly consistent with the actual situation. Through process innovation, flow channel optimization, and improvements to key equipment, this invention ultimately achieves cross-contamination-free and long-term stable sampling of trace SF6 gas, providing highly reliable sample introduction assurance for modern analytical instruments.

[0028] In some embodiments, the sample introduction unit includes a pump 2 and a sample introduction line, with the inlet end of the pump 2 connected to the sample inlet 1. The pump 2 draws in the sample under suction, while simultaneously providing power for the transport of the sample gas. In some embodiments, the constant pressure control unit includes: a pressure regulating valve 3 and a buffer tank 4; the pressure regulating valve 3 is installed on the sample inlet pipeline, and the buffer tank 4 is installed on a branch of the sample inlet pipeline. The inlet end of the buffer tank 4 is connected to the sample inlet pipeline, and the outlet end of the buffer tank 4 is connected to the sample outlet pipeline; the inlet end and outlet end of the buffer tank 4 are respectively provided with a buffer tank front valve 9 and a buffer tank rear valve 8; the first port I of the six-way valve 5 is connected to the buffer tank front valve 9 and the pressure regulating valve 3 respectively, and the pressure stabilization is achieved by absorbing pressure pulsations through the large gas capacity of the buffer tank 4.

[0029] In some embodiments, the six-way valve is a precision fluid control valve with six fluid channel ports, whose six ports (I, II, III, IV, V, VI) are respectively connected to different gas paths to achieve sampling, analysis and cleaning functions.

[0030] In some embodiments, the two ends of the quantitative sampling loop 6 are connected to the second port II and the fifth port V of the six-way valve 5, respectively; the quantitative sampling loop 6 is a section of tubing with a precise and fixed volume, used to ensure the consistency of the injection volume each time.

[0031] In some embodiments, the quantitative sampling loop 6 is further provided with a heating device 19 for heating the quantitative sampling loop during the cleaning stage.

[0032] In some embodiments, the flow channel cleaning system includes: a high-purity inert cleaning gas source, a cleaning gas path, a six-way valve 5, and a quantitative sampling loop 6. The high-purity inert cleaning gas source is the carrier gas used in the analytical instrument (such as high-purity nitrogen). One end of the cleaning gas path is connected to the sample inlet pipe and the high-purity inert cleaning gas source, and the other end is connected to the sample outlet pipe. The sample inlet pipe is connected to the third port III of the six-way valve 5, and the sample outlet pipe is connected to the fourth port IV of the six-way valve 5. The sample outlet pipe and the sample inlet pipe are connected to the quantitative sampling loop 6 via the gas path. By using the flow channel cleaning system to alternately flush the quantitative sampling loop 6 in both forward and reverse directions, cross-contamination of the sample gas is fundamentally eliminated.

[0033] In some embodiments, a cleaning gas forward-blowing inlet valve 12 is provided between the cleaning gas path and the sample inlet pipeline; a cleaning gas back-blowing inlet valve 15 is provided between the cleaning gas path and the sample outlet pipeline; a sample inlet valve 14 is provided on the sample inlet pipeline; a sample outlet valve 17 is provided on the sample outlet pipeline; and a sample bypass valve 18 is provided on the cleaning gas path to form a closed cleaning pipeline, thereby realizing the quantitative sampling loop and alternating forward and reverse flushing of the pipeline.

[0034] In some embodiments, a cleaning gas forward purge outlet valve 16 is provided on the branch line connecting the cleaning gas path to the sample inlet pipeline; a cleaning gas backflush outlet valve 13 is provided on the branch line connecting the cleaning gas path to the sample outlet pipeline to discharge high-purity cleaning gas.

[0035] In some embodiments, a six-way valve inlet valve 10 is also provided at the inlet end of the six-way valve 5 on the sample injection line; and a six-way valve outlet valve 11 is also provided at the outlet end of the six-way valve 5 on the sample outlet line to control the connection or closure of the gas with the six-way valve 5.

[0036] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0037] This invention provides a trace SF6 gas sampler with no memory effect, the structure of which is as follows: Figure 1 and Figure 2 As shown, this sampler achieves cross-contamination-free collection and long-term stable sampling of trace SF6 gas through an integrated flow channel cleaning system and a constant pressure control system centered on a buffer tank.

[0038] The technical solution of the present invention specifically includes the following structure, configuration, connection relationship, and functional relationship: 1. Overall Structure The trace SF6 gas sampler of the present invention mainly includes: a sample injection unit, a constant pressure control unit, a six-way valve, a quantitative sampling loop, a sample injection analysis system, a flow channel cleaning system, and pipelines and valves connecting the various components.

[0039] 2. Structure and connection relationships of each component Sample injection unit: includes an externally connected sample injection line and a pump 2. The inlet end of the pump 2 is connected to the sample injection port 1 for extracting samples and providing power for transporting sample gas.

[0040] Constant pressure control unit: This unit is the core of solving the flow rate fluctuation problem. It includes a pressure regulating valve 3 and a buffer tank 4. The outlet of pump 2 is connected to the inlet of pressure regulating valve 3, and the outlet of pressure regulating valve 3 is connected to the first port I of six-way valve 5. Buffer tank 4, as the core of this unit, has its inlet valve 9 directly connected to the first port I of six-way valve 5, forming a closed system with six-way valve 5 and quantitative sampling ring 6. It utilizes its large gas capacity to absorb pressure pulsations and achieve precise pressure stabilization.

[0041] The six-way valve 5 is the core component for switching gas flow paths. Its six ports I, II, III, IV, V, and VI are connected to different gas paths to achieve sampling, analysis, and cleaning functions.

[0042] Quantitative sampling loop 6: A tubing section with a precise, fixed volume to ensure consistent sample volume for each injection. It connects between the second port II and the fifth port V of the six-way valve 5. To enhance the purging effect, the quantitative sampling loop 6 can be equipped with an external heating device 19 for heating the loop during the cleaning phase.

[0043] Specifically, under the suction of pump 2, the SF6 sample gas passes through inlet 1, pressure regulating valve 3, and six-way valve inlet valve 10, then enters port I of six-way valve 5. In sampling mode, the internal flow path of six-way valve 5 is open, allowing the gas to flow sequentially through port I, port II, quantitative sampling ring 6, and port V, finally exiting from port VI through six-way valve outlet valve 11 and outlet 7. Simultaneously, another stream of gas passes through buffer tank front valve 9, buffer tank 4, and buffer tank rear valve 8, exiting from outlet 7. After quantitative sampling ring 6 is filled, pressure regulating valve 3 and six-way valve outlet valve 11 are closed, connecting quantitative sampling ring 6 to buffer tank 4. Utilizing the large gas capacity of buffer tank 4, precise pressure stabilization is achieved.

[0044] Flow path cleaning system: This system is crucial for eliminating cross-contamination of gases. It includes a high-purity inert cleaning gas source, a cleaning gas control valve, a six-way valve 5, a quantitative sampling loop 6, and a cleaning gas path. In the cleaning state, the sample inlet valve 14 and sample outlet valve 17 are closed, while the sample bypass valve 18 is open. High-purity cleaning gas, such as high-purity nitrogen, is introduced into the six-way valve 5. At this time, the internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, allowing the high-purity cleaning gas to flow sequentially through the cleaning gas forward purge inlet valve 12, the third port III of the six-way valve 5, the second port II, the quantitative sampling loop 6, and the fifth port V, finally exiting from the fourth port IV through the cleaning gas forward purge outlet valve 16. This flow path design achieves unidirectional purging of the quantitative sampling loop 6. The control unit can also be switched to the backflushing position. The internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, so that the high-purity cleaning gas flows sequentially through the cleaning gas backflushing inlet valve 15, the fourth port IV, the fifth port V of the six-way valve 5, the quantitative sampling ring 6, the second port II, and finally discharged from the third port III through the cleaning gas backflushing outlet valve 13. This flow path design realizes the reverse purging of the quantitative sampling ring 6.

[0045] 3. Working Process and Principle The working process of this invention is divided into sampling and voltage stabilization, sample injection analysis, and flow path cleaning. The specific steps are as follows: Phase 1: Sampling and Precision Voltage Regulation With the six-way valve 5 in the "sampling position," the SF6 sample gas, under the suction of pump 2, enters the first port I of the six-way valve 5 after passing through the inlet 1, pressure regulating valve 3, and the six-way valve inlet valve 10. In the sampling state, the internal flow path of the six-way valve 5 is open, allowing the gas to flow sequentially through the first port I, the second port II, the quantitative sampling ring 6, and the fifth port V, finally exiting from the sixth port VI through the six-way valve outlet valve 11 and the sample outlet 7. Simultaneously, another stream of gas passes through the buffer tank front valve 9, the buffer tank 4, and the buffer tank rear valve 8, exiting from the sample outlet 7. After the quantitative sampling ring 6 is full, the pressure regulating valve 3 and the six-way valve outlet valve 11 are closed, connecting the quantitative sampling ring 6 to the buffer tank 4. Utilizing the large gas capacity of the buffer tank 4, precise pressure stabilization is achieved. Due to the large gas capacity of the buffer tank 4, any minute pressure fluctuations in the system are absorbed, resulting in a highly stable gas pressure within the quantitative sampling ring 6. This process, through a constant pressure control system centered on buffer tank 4, fundamentally solves the pressure fluctuation problem and ensures the accuracy of the sampling.

[0046] Phase Two: Sample Injection Analysis Once the pressure inside the quantitative sampling loop 6 stabilizes, the control unit drives the six-way valve 5 to quickly switch to the "sample injection position".

[0047] At this time, the purge gas forward inlet valve 12, purge gas backflush outlet valve 13, purge gas backflush inlet valve 15, purge gas forward inlet valve 16, and sample bypass valve 18 are closed; the internal flow path of the six-way valve 5 is switched, and the carrier gas used by the analyzer is connected to the sample inlet valve 14. The gas passes through the sample inlet valve 14, the third port III, the second port II, the quantitative sampling loop 6, the fifth port V, the fourth port IV of the six-way valve 5, and the sample outlet valve 17, which is connected to the sample inlet of the analyzer. At this time, the carrier gas pushes the fixed volume and constant pressure of SF6 sample gas in the quantitative sampling loop 6 into the analyzer for detection.

[0048] Phase 3: Flow path cleaning After the sample is injected, the control unit activates the flow channel cleaning system to eliminate the memory effect.

[0049] Forward flushing: such as Figure 2 As shown, the sample inlet valve 14 and sample outlet valve 17 are closed, while the sample bypass valve 18 is open, ensuring that the carrier gas entering the analytical equipment is not affected. High-purity cleaning gas, such as high-purity nitrogen, is introduced into the six-way valve 5. At this time, the internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, allowing the high-purity cleaning gas to flow sequentially through the cleaning gas forward purge inlet valve 12, the third port III of the six-way valve 5, the second port II, the quantitative sampling loop 6, and the fifth port V, and finally exit from the fourth port IV through the cleaning gas forward purge outlet valve 16. This flow path design achieves unidirectional purging of the quantitative sampling loop 6. The control unit can also be switched to the backflushing position, where the internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, allowing the high-purity cleaning gas to flow sequentially through the cleaning gas backflushing inlet valve 15, the fourth port IV of the six-way valve 5, the fifth port V, the quantitative sampling loop 6, and the second port II, and finally exit from the third port III through the cleaning gas backflushing outlet valve 13. This process performs unidirectional purging of the quantitative sampling loop. During this process, the control unit can simultaneously activate the external heating device 19 of the quantitative sampling ring 6 to reduce the gas viscosity and promote the decomposition and adsorption of the adsorbent group, thereby enhancing the purging effect.

[0050] Backflushing: To further eliminate dead zone residue, the control unit can again control the six-way valve 5 to the backflushing position. The internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, allowing the high-purity cleaning gas to flow sequentially through the cleaning gas backflushing inlet valve 15, the fourth port IV, the fifth port V of the six-way valve 5, the quantitative sampling ring 6, the second port II, and finally discharged from the third port III through the cleaning gas backflushing outlet valve 13. This flow path design achieves reverse purging of the quantitative sampling ring 6. This backflushing can effectively strip and purge away trace amounts of residual gas adsorbed on the pipe wall, valve components, and the inner wall of the buffer tank. Similarly, this process can also be combined with the heating device 19 of the quantitative sampling ring 6 to achieve a more thorough cleaning.

[0051] This embodiment uses a flow channel cleaning system to alternately rinse the quantitative sampling loop in both forward and reverse directions, fundamentally eliminating cross-contamination of gases.

[0052] Furthermore, such as Figure 1 The diagram illustrates the structural connections and gas flow direction of this invention during SF6 gas sampling and pressure stabilization. The trace SF6 gas sampler of this invention includes an inlet 1, a pump 2, a pressure regulating valve 3, a buffer tank 4, a six-way valve 5, a quantitative sampling ring 6, an outlet 7, a buffer tank rear valve 8, a buffer tank front valve 9, a six-way valve inlet valve 10, and a six-way valve outlet valve 11. Under the suction of the pump 2, the SF6 sample gas passes through the inlet 1, pressure regulating valve 3, and six-way valve inlet valve 10, then enters the first port of the six-way valve 5. During sampling, the internal flow path of the six-way valve 5 is open, allowing the gas to flow sequentially through the first port, the second port II, the quantitative sampling ring 6, and the fifth port V, finally exiting from the sixth port VI through the six-way valve outlet valve 11 and the outlet 7. Simultaneously, another gas stream passes through the buffer tank front valve 9, the buffer tank 4, and the buffer tank rear valve 8, exiting from the outlet 7. After the quantitative sampling ring 6 is filled, close the pressure regulating valve 3 and the six-way valve outlet valve 11 to connect the quantitative sampling ring 6 to the buffer tank 4. Utilizing the large gas capacity of the buffer tank 4, precise pressure stabilization is achieved. To enhance the purging effect, a heating device 19 can be installed on the outside of the quantitative sampling ring 6.

[0053] Furthermore, such as Figure 2 As shown, this invention demonstrates the structural connections and gas flow direction that, after sampling, involve sample introduction detection and cleaning of the flow path to eliminate memory effects.

[0054] In the sample injection analysis state, the purge gas forward blow inlet valve 12, purge gas backflush outlet valve 13, purge gas backflush inlet valve 15, purge gas forward blow outlet valve 16, and sample injection bypass valve 18 are in the closed state; the internal flow path of the six-way valve 5 is switched, the carrier gas used by the analyzer is connected to the sample injection inlet valve 14, and the gas enters the equipment for analysis through the sample injection inlet valve 14, the third interface III, the second interface II, the quantitative sampling loop 6, the fifth interface V, the fourth interface IV, and the sample injection outlet valve 17.

[0055] In the cleaning state, the sample inlet valve 14 and sample outlet valve 17 are closed, while the sample bypass valve 18 is open. High-purity cleaning gas, such as high-purity nitrogen, is introduced into the six-way valve 5. At this time, the internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, allowing the high-purity cleaning gas to flow sequentially through the cleaning gas forward purge inlet valve 12, the third port III of the six-way valve 5, the second port II, the quantitative sampling loop 6, and the fifth port V, finally exiting from the fourth port IV through the cleaning gas forward purge outlet valve 16. This flow path design achieves unidirectional purging of the quantitative sampling loop 6. The control unit can also be switched to the backflushing position, where the internal flow path of the six-way valve 5 is consistent with the sample injection analysis state, allowing the cleaning gas to flow sequentially through the cleaning gas backflushing inlet valve 15, the fourth port IV of the six-way valve 5, the fifth port V, the quantitative sampling loop 6, and the second port II, finally exiting from the third port III through the cleaning gas backflushing outlet valve 13. This flow path design achieves reverse purging of the quantitative sampling loop 6. By purging in both directions, residual gas from the previous batch of samples was effectively removed from the system, fundamentally eliminating cross-contamination and ensuring the accuracy and reliability of the next sampling.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A trace SF6 gas sampler with no memory effect, characterized in that, include: Sample injection unit, constant pressure control unit, six-way valve (5), quantitative sampling ring (6), gas pipeline, control valve; The injection unit includes: an injection pipeline and a pump 2. The injection pipeline is equipped with a pump (2). The end of the injection pipeline away from the injection port 1 is connected to a six-way valve (5). The six-way valve (5) is connected to a quantitative sampling ring (6) through a gas pipeline. A constant pressure control unit is installed on the pipeline between the injection unit and the six-way valve (5); the constant pressure control unit includes: a pressure regulating valve and a buffer tank; the six-way valve (5) can be connected to the injection analysis system, the flow channel cleaning system, the injection pipeline, and the outlet pipeline respectively; The six-way valve (5) includes six ports (I, II, III, IV, V, VI).

2. The memory-free trace SF6 gas sampler as described in claim 1, characterized in that, The injection unit includes at least one pump (2) and an injection pipe, wherein the pump (2) is installed on the injection pipe and the inlet end of the pump (2) is connected to the injection port (1).

3. The memory-free trace SF6 gas sampler as described in claim 1, characterized in that, The constant pressure control unit includes a pressure regulating valve (3) and a buffer tank (4); the pressure regulating valve (3) is installed on the sample inlet pipe, and the buffer tank (4) is installed on a branch of the sample inlet pipe. The inlet end of the buffer tank (4) is connected to the sample inlet pipe, and the outlet end of the buffer tank (4) is connected to the sample outlet pipe; the inlet end and outlet end of the buffer tank (4) are respectively provided with a buffer tank front valve (9) and a buffer tank rear valve (8); the first port (I) of the six-way valve (5) is connected to the buffer tank front valve (9) and the pressure regulating valve (3) respectively.

4. The memory-free trace SF6 gas sampler as described in claim 1, characterized in that, The two ends of the quantitative sampling ring (6) are connected to the second port (II) and the fifth port (V) of the six-way valve (5), respectively; the quantitative sampling ring (6) is also provided with a heating device (19).

5. The memory-free trace SF6 gas sampler as described in claim 1, characterized in that, The flow channel cleaning system includes: a high-purity inert cleaning gas source, a cleaning gas path, a six-way valve (5), and a quantitative sampling ring (6); the high-purity inert cleaning gas source is the carrier gas used by the analytical instrument; one end of the cleaning gas path is connected to the sample inlet pipeline and the high-purity inert cleaning gas source, and the other end is connected to the sample outlet pipeline; the sample inlet pipeline is connected to the third interface (III) of the six-way valve (5), and the sample outlet pipeline is connected to the fourth interface (IV) of the six-way valve (5); the sample outlet pipeline and the sample inlet pipeline are connected to the quantitative sampling ring (6) through the gas path.

6. The memory-free trace SF6 gas sampler as described in claim 1, characterized in that, A cleaning gas forward blowing inlet valve (12) is provided between the cleaning gas path and the sample inlet pipeline; a cleaning gas back blowing inlet valve (15) is provided between the cleaning gas path and the sample outlet pipeline; a sample inlet valve (14) is provided on the sample inlet pipeline; a sample outlet valve (17) is provided on the sample outlet pipeline; and a sample bypass valve (18) is provided on the cleaning gas path.

7. The memory-free trace SF6 gas sampler as described in claim 1, characterized in that, A cleaning gas positive blowing outlet valve (16) is installed on the branch line connecting the cleaning gas path and the sample inlet pipeline. A backflush outlet valve (13) for cleaning gas is installed on the branch line connecting the cleaning gas path and the sample inlet / outlet pipeline.

8. The memory-free trace SF6 gas sampler as described in claim 1, characterized in that, On the sample inlet line, a six-way valve inlet valve (10) is also provided at the inlet end of the six-way valve (5); on the sample outlet line, a six-way valve outlet valve (11) is also provided at the outlet end of the six-way valve (5).

9. A method for sampling using the memory-free trace SF6 gas sampler according to any one of claims 1-8, characterized in that, include: Under the suction action of the pump (2), the SF6 sample gas passes through the inlet (1), the pressure regulating valve (3) and the inlet valve (10) of the six-way valve, and then enters the first port (Ⅰ) of the six-way valve (5). In the sampling state, the internal flow path of the six-way valve (5) is open, allowing the gas to flow sequentially through the first port (Ⅰ), the second port (Ⅱ), the quantitative sampling ring (6), and the fifth port (Ⅴ), and finally be discharged from the sixth port (Ⅵ) through the six-way valve outlet valve (11) and the sample outlet (7); Meanwhile, another gas passes through the front valve (9) of the buffer tank, the buffer tank (4), and the rear valve (8) of the buffer tank, and is discharged from the outlet (7); After the quantitative sampling loop (6) is filled, close the pressure regulating valve (3) and the six-way valve outlet valve (11) to connect the quantitative sampling loop (6) with the buffer tank (4) and obtain a gas sample with stable pressure.

10. A method for cleaning flow channels using a memory-free trace SF6 gas sampler as described in any one of claims 1-8, characterized in that, include: In the cleaning state, the sample inlet valve (14) and sample outlet valve (17) are closed, and the sample bypass valve (18) is open. High-purity cleaning gas is introduced into the six-way valve (5). The internal flow path of the six-way valve (5) is consistent with the sample injection analysis state, so that the high-purity cleaning gas flows through the cleaning gas forward blow inlet valve (12), the third port (Ⅲ), the second port (Ⅱ), the quantitative sampling ring (6), and the fifth port (Ⅴ) of the six-way valve (5) in sequence, and finally exits from the fourth port (Ⅳ) through the cleaning gas forward blow outlet valve (16). Alternatively, reverse purging can be performed, and the internal flow path of the six-way valve (5) can be kept consistent with the sample injection analysis state, so that the high-purity cleaning gas flows sequentially through the cleaning gas backflush inlet valve (15), the fourth port (Ⅳ) and the fifth port (Ⅴ) of the six-way valve (5), the quantitative sampling ring (6), and the second port (Ⅱ), and finally exits from the third port (Ⅲ) through the cleaning gas backflush outlet valve (13).

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