A gas-enriched sulfur hexafluoride decomposition product on-site sampling device and method

Abstract

A gas-enriched sulfur hexafluoride decomposition product on-site sampling device and method, in the technical field of power system detection, solves the problem of low accuracy in sulfur hexafluoride gas detection due to low decomposition product content; the sampling device of the present invention circulates and separates the sample gas sampled in the piston-type gas premixing chamber through a chromatographic column separation device, detects the gas separated by the chromatographic column separation device through a thermal conductivity detector, and injects the gas into a piston-type SF6 buffer chamber and a piston-type decomposition product collection chamber for enrichment respectively; the sample gas can be circulated, separated and enriched according to the concentration requirements of the detection gas, and can effectively improve the detection limit of the decomposition product in the sample, thereby solving the problem of low accuracy in sulfur hexafluoride gas detection due to low decomposition product content, and improving the accuracy of detection.

Description

Technical Field

[0001] The invention belongs to the technical field of power system detection, and relates to an on-site sampling device and method for gas-enriched sulfur hexafluoride decomposition products. Background Art

[0002] Sulfur hexafluoride is currently the gas insulating medium with the most comprehensive performance and the best insulation and arc extinguishing ability, and plays an important role in high-voltage equipment. In theory, the intermediate products of sulfur hexafluoride gas molecules dissociated under high temperature or discharge conditions will recombine into sulfur hexafluoride molecules after high temperature or discharge ends. However, in actual situations, the sulfur hexafluoride gas in the equipment is not a pure substance, and there are trace amounts of impurities such as moisture and oxygen. At the same time, there are metal and non-metal materials in the conductive parts and walls of the equipment. In the presence of these substances, redox reactions and hydrolysis reactions will occur after sulfur hexafluoride dissociates, generating a series of complex decomposition products such as fluorides and sulfides.

[0003] The decomposition products of sulfur hexafluoride gas are of various types, extremely low concentrations, and most of them are acidic and toxic. Therefore, these decomposition products are very harmful to electrical equipment and operation and maintenance personnel. At the same time, there is a correlation between the type and content of decomposition products and equipment failure. By analyzing the type and content of decomposition products, it can be used to analyze and judge the type of equipment failure and the size of the failure energy. It can be seen that the accurate determination of sulfur hexafluoride decomposition products in electrical equipment is of great practical significance. However, due to the low amount of decomposition products generated, coupled with the adsorption of solid materials such as adsorbents and walls, the content of decomposition products in the gas is further reduced to ppm or even ppb levels, which brings great challenges to the detection work.

[0004] At present, the detection technology of decomposition products mainly includes electrochemical sensor method and gas chromatography method. Other methods include photoacoustic spectroscopy, infrared spectroscopy, gas detection tube method, etc. The on-site portable decomposition product detector is mainly the electrochemical sensor method. This method has a fast detection speed and low gas consumption, but the detection sensitivity is low. Gas chromatography has relatively high detection accuracy and many detection components, but the detection speed is slow and has high environmental requirements. It is mostly used for laboratory testing. Although portable gas chromatographs can be used for on-site detection, they are limited by the structure of the instrument and the influence of the environment. The stability of the instrument is poor and the detection accuracy cannot be guaranteed.

[0005] Whether it is on-site live testing or sampling in the laboratory for testing, sulfur hexafluoride gas is directly taken from electrical equipment for testing. Due to the low content of decomposition products and the limitation of instrument detection accuracy, low-concentration decomposition products are usually difficult to detect accurately and stably. In the case that no substantial breakthrough can be made in instrument performance, one idea to solve the problem of uncertainty is to pre-treat the test sample so that the content of decomposition products reaches the concentration range that can be accurately measured by the instrument, thereby achieving accurate measurement. However, no relevant technology or products have been put into practical application yet.

[0006] In the prior art, the Chinese invention patent application "An SF6 intermediate decomposition product separation device and its use method" with application publication number CN105424419A and application publication date March 23, 2016, uses the different boiling points of decomposition products and SF6 to achieve separation of decomposition products and SF6 through cold trap temperature control and adsorbent adsorption, thereby improving detection accuracy. This method requires cold trap refrigeration, which has high energy consumption, and it is difficult to achieve complete decomposition of decomposition products by simply controlling the temperature, resulting in partial loss of decomposition products, which in turn affects subsequent detection results. At the same time, the above method requires a large amount of gas to achieve a better separation effect, which may cause the equipment to use too much gas and affect the insulation strength, endangering the safe operation of the equipment. Summary of the invention

[0007] The invention is used to solve the problem of low accuracy in sulfur hexafluoride gas detection caused by low content of decomposition products.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] A gas-enriched sulfur hexafluoride decomposition product on-site sampling device comprises: a chromatographic column separation device (1), a thermal conductivity detector (2), a piston-type SF6 buffer chamber (3), a piston-type decomposition product collection chamber (4), a piston-type gas premixing chamber (5), a piston-type SF6 gas power chamber (6), a mass flow meter (9), a booster pump (10), a first three-way valve (11), a second three-way valve (12), a third three-way valve (13), a fourth three-way valve (14), a fifth three-way valve (15), and a sixth three-way valve (16); the first three-way valve (11) and the second three-way valve (12) are connected to the first three-way valve (11); the second three-way valve (12) and the third three-way valve (13 ... fourth three-way valve (14); the second three-way valve (15) and the sixth three-way valve (16) are connected to the first three-way valve (11); # The port is sealedly connected to one end of the mass flow meter (9), and the other end of the mass flow meter (9) is sealed to one end of the second three-way valve (12). # Port seal connection, 2nd three-way valve (12) # The port is connected to the third three-way valve (13). # Port seal connection, third three-way valve (13) 2 # The port is sealedly connected to the piston-type decomposition product collection chamber (4), and the 3-way valve of the second three-way valve (12)# Port 1 of the fourth three-way valve (14) # The piston-type gas premixing chamber (5) is sealed and connected to the 3-way valve (12) of the second three-way valve (12). # Port 1 of the fourth three-way valve (14) # On the pipeline between the ports, the fourth three-way valve (14) # The port is sealed and connected to the input end of the chromatographic column separation device (1), the output end of the chromatographic column separation device (1) is sealed and connected to the input end of the thermal conductivity detector (2), and the output end of the thermal conductivity detector (2) is sealed and connected to the 1 end of the fifth three-way valve (15). # Port seal connection, fifth three-way valve (15) 2 # The port is sealed and connected to the piston type SF6 buffer chamber (3). The 3 # The port is connected to the third three-way valve (13). # The piston-type SF6 gas power chamber (6) is sealed and connected to the fourth three-way valve (14) 2 # Port; 2 of the fourth three-way valve (14) # Port 3 of the sixth three-way valve (16) # The ports are sealed and connected, and the input port of the booster pump (10) is connected to the 1st of the sixth three-way valve (16). # The ports are sealed and connected, and the output port of the booster pump (10) is connected to the 3-way port of the first three-way valve (11). # Port seal connection, 2 of the sixth three-way valve (16) # Port 2 of the fifth three-way valve (15) # Port sealed connections.

[0010] The sampling device of the present invention circulates and separates the sample gas sampled from the piston-type gas premixing chamber (5) through a chromatographic column separation device (1), and detects the gas separated by the chromatographic column separation device (1) through a thermal conductivity detector (2), so that pure SF6 gas and impurity-containing SF6 gas are respectively injected into the piston-type SF6 buffer chamber (3) or the piston-type decomposition product collection chamber (4). The sample gas can be circulated, separated and enriched according to the concentration requirements of the detection gas, which can effectively improve the detection limit of the decomposition product in the sample, thereby solving the problem of low accuracy in sulfur hexafluoride gas detection due to low decomposition product content, and improving the detection accuracy.

[0011] Furthermore, the gas-enriched sulfur hexafluoride decomposition product on-site sampling device further comprises: a first pressure gauge (7), wherein the first pressure gauge (7) is sealedly connected to the 3-way valve of the fourth three-way valve (14). # On the pipeline between the port and the input end of the chromatographic column separation device (1).

[0012] Furthermore, the gas-enriched sulfur hexafluoride decomposition product on-site sampling device further comprises: a second pressure gauge (8), the second pressure gauge (8) being sealed and connected to the second end of the sixth three-way valve (16). # Port 2 of the fifth three-way valve (15) # On the pipe between the ports.

[0013] A method for the on-site sampling device of the gas-enriched sulfur hexafluoride decomposition product comprises the following steps: S1, sampling of sample gas; S2, primary separation of sample gas; S3, primary enrichment of sample gas; S4, cyclic separation and enrichment of sample gas; S5, recharging of SF6 gas.

[0014] Furthermore, the method for sampling the sample gas in step S1 is as follows: # After the port is sealed and connected to the SF6 gas chamber of the device to be tested, open the first three-way valve (11) # , 2 # port and the second three-way valve (12) # , 3 # The port is used to extract SF6 sample gas from the SF6 gas chamber of the device to be tested and inject it into the piston-type gas premixing chamber (5), and the amount of the sampled SF6 gas is recorded by a mass flow meter (9).

[0015] Furthermore, the method for primary separation of the sample gas in step S2 is as follows: Open the fourth three-way valve (14) # , 3 # The piston is pushed to inject all the SF6 sample gas in the piston-type gas premixing chamber (5) into the chromatographic column separation device (1) at a constant pressure, and then the fourth three-way valve (14) is opened. # , 3 # The pure SF6 gas in the piston-type SF6 gas power chamber (6) is injected into the chromatographic column separation device (1) at a constant pressure, thereby pushing the SF6 sample gas to complete a separation.

[0016] Furthermore, the method for primary enrichment of the sample gas in step S3 is as follows: the thermal conductivity detector (2) detects the thermal conductivity of the gas separated by the chromatographic column separation device (1); when the gas flowing through the thermal conductivity detector (2) is pure SF6 gas, the fifth three-way valve (15) is opened. # , 2 # The pure SF6 gas is injected into the piston-type SF6 buffer chamber (3) through a port; when the gas flowing through the thermal conductivity detector (2) is SF6 gas containing decomposition products, the fifth three-way valve (15) is opened. # , 3 #port and the third three-way valve (13) # , 3 # The SF6 gas containing the decomposition products is injected into the piston-type decomposition product collecting chamber (4) for primary enrichment.

[0017] Furthermore, the method for circulating separation and enrichment of the sample gas in step S4 is as follows: close the fifth three-way valve (15) and the fourth three-way valve (14), open the sixth three-way valve (16) # , 3 # The port is used to inject a certain volume of pure SF6 gas in the piston-type SF6 buffer chamber (3) into the piston-type SF6 gas power chamber (6); the second three-way valve (12) is opened. # , 3 # port and the third three-way valve (13) # , 2 # port, close the fourth three-way valve (14), transfer the gas in the piston-type decomposition product collection chamber (4) to the piston-type gas premixing chamber (5), and then repeat steps S1 to S3 for cyclic separation and enrichment.

[0018] Furthermore, the method for recharging SF6 gas in step S5 is as follows: Open the first three-way valve (11) # , 3 # port and the sixth three-way valve (16) # , 2 # The fifth three-way valve (15) is closed, and the booster pump (10) is started to inject the pure SF6 gas in the piston-type SF6 buffer chamber (3) into the SF6 gas chamber of the device to be tested through the booster pump (10).

[0019] The advantages of the present invention are:

[0020] (1) The sampling device of the present invention circulates and separates the sample gas sampled from the piston-type gas premixing chamber (5) through the chromatographic column separation device (1), detects the gas separated by the chromatographic column separation device (1) through the thermal conductivity detector (2), and injects the gas into the piston-type SF6 buffer chamber (3) and the piston-type decomposition product collection chamber (4) for enrichment. The sample gas can be circulated, separated and enriched according to the concentration requirements of the detection gas, which can effectively improve the detection limit of the decomposition product in the sample, thereby solving the problem of low accuracy in sulfur hexafluoride gas detection due to low decomposition product content, and improving the detection accuracy;

[0021] (2) The piston-type SF6 gas power chamber (6) is filled with pure SF6 gas as the driving gas, which can effectively avoid the introduction of other gas impurities and facilitate the subsequent refilling of SF6 gas;

[0022] (3) A thermal conductivity detector (2) is arranged after the chromatographic column separation device (1), so as to qualitatively identify the purity of SF6 gas at the outlet of the chromatographic column at low cost and high efficiency;

[0023] (4) After the test, the sulfur hexafluoride background gas is directly refilled into the original equipment through the refill pipeline, which can not only restore the insulation performance of the equipment in time and reduce the large consumption of SF6 gas in the equipment, but also reduce the emission of SF6 tail gas caused by the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1 is a structural diagram of a gas-enriched sulfur hexafluoride decomposition product on-site sampling device according to Embodiment 1 of the present invention;

[0025] Figure 2 This is a working flow chart of the on-site sampling device for gas-enriched sulfur hexafluoride decomposition products according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0028] Embodiment 1

[0029] 1. Structure of the device

[0030] like Figure 1 As shown, a gas-enriched sulfur hexafluoride decomposition product on-site sampling device includes: a chromatographic column separation device 1, a thermal conductivity detector 2, a piston-type SF6 buffer chamber 3, a piston-type decomposition product collection chamber 4, a piston-type gas premixing chamber 5, a piston-type SF6 gas power chamber 6, a first pressure gauge 7, a second pressure gauge 8, a mass flow meter 9, a booster pump 10, a first three-way valve 11, a second three-way valve 12, a third three-way valve 13, a fourth three-way valve 14, a fifth three-way valve 15, and a sixth three-way valve 16.

[0031] The first three-way valve 11 # The port is used as the external port of the device and is sealed and connected to the SF6 gas chamber of the device under test. The 2 # The port is sealed and connected to one end of the mass flow meter 9, and the other end of the mass flow meter 9 is connected to the 1 end of the second three-way valve 12. #Port seal connection, second three-way valve 12 of 2 # Port 1 of the third three-way valve 13 # Port seal connection, third three-way valve 13 of 2 # The port is sealed and connected to the piston type decomposition product collecting chamber 4, and the 3 # Port 1 of the fourth three-way valve 14 # The piston-type gas premixing chamber 5 is sealed and connected to the 3 of the second three-way valve 12. # Port 1 of the fourth three-way valve 14 # On the pipeline between the ports, the fourth three-way valve 14 # The port is sealed and connected to the input end of the chromatographic column separation device 1, and the first pressure gauge 7 is sealed and connected to the 3 of the fourth three-way valve 14. # The output end of the chromatographic column separation device 1 is sealed and connected to the input end of the thermal conductivity detector 2, and the output end of the thermal conductivity detector 2 is sealed and connected to the 1 end of the fifth three-way valve 15. # Port seal connection, fifth three-way valve 15 of 2 # The port is sealed and connected to the piston type SF6 buffer chamber 3, and the 3 of the fifth three-way valve 15 # Port 3 of the third three-way valve 13 # Port sealing connection, the fourth three-way valve 14 of 2 # Port 3 of the sixth three-way valve 16 # The port is sealed and connected, and the piston type SF6 gas power chamber 6 is sealed and connected to the 2 of the fourth three-way valve 14 # Port 3 of the sixth three-way valve 16 # The input port of the booster pump 10 is connected to the 1st of the sixth three-way valve 16. # The ports are sealed and connected, and the output port of the booster pump 10 is connected to the 3-way valve 11. # Port seal connection, sixth three-way valve 16 of 2 # Port 2 of the fifth three-way valve 15 # The port is sealed and connected, and the second pressure gauge 8 is sealed and connected to the 2 of the sixth three-way valve 16 # Port 2 of the fifth three-way valve 15 # On the pipe between the ports.

[0032] The chromatographic column separation device 1 is used to separate the decomposition products and SF6 gas in the sampled gas. The separation and enrichment effect can be adjusted by changing the type, amount and ratio of the stationary phase filled in the chromatographic column separation device 1; the piston-type SF6 buffer chamber 3 is used to collect the separated pure SF6 gas; the piston-type decomposition product collection chamber 4 is used to collect the decomposition product gas after separation and enrichment; the piston-type SF6 gas power chamber 6 is used to store quantitative pure SF6 and push the SF6 sample entering the chromatographic column separation device 1 to complete the separation. The piston-type gas premixing chamber 5 and the piston-type SF6 gas power chamber 6 are used to provide a constant gas pressure. After all the sample gas in the piston-type gas premixing chamber 5 enters the chromatographic column separation device 1, the piston-type SF6 gas power chamber 6 provides pure SF6 to push the sample gas in the chromatographic column separation device 1 to continue to move forward to complete the separation. The front end of the chromatographic column separation device 1 is connected to a first pressure gauge 7, and the connecting pipeline between the piston-type SF6 buffer chamber 3 and the sixth three-way valve 16 is connected to a second pressure gauge 8. The first pressure gauge 7 and the second pressure gauge 8 are used to display the gas pressure in the corresponding pipeline. The mass flowmeter 9 can accurately measure the total amount of SF6 gas sample extracted from the SF6 gas chamber of the device to be tested, which is used for the conversion of the subsequent concentrated gas concentration detection results; the pipelines of the sampling device are all made of polytetrafluoroethylene or stainless steel pipes with polished inner walls, which can effectively avoid the adsorption and chemical reaction of decomposition products.

[0033] 2. Workflow of the device

[0034] like Figure 2 As shown, the working process of the on-site sampling device for gas-enriched sulfur hexafluoride decomposition products according to the embodiment of the present invention is as follows:

[0035] 1) Before concentrated sampling, the piston-type SF6 gas power chamber 6 is pre-injected with pure SF6 gas with a volume of V0, which is used as the gas driving source in the sampling device. The sampling device is connected to the first three-way valve 11 through 1 # After the port is sealed and connected to the SF6 gas chamber of the device to be tested, the piston-type gas premixing chamber 5 passes through the first three-way valve 11. # , 2 # Port, 1 of the second three-way valve 12 # , 3 # The port extracts SF6 sample gas with a volume of V1 from the SF6 gas chamber of the device to be tested, and records the sampled SF6 gas volume through the mass flow meter 9.

[0036] 2) Open the fourth three-way valve 14 # , 3 # The piston of the piston-type gas premixing chamber 5 is used to push the SF6 sample gas into the chromatographic column separation device 1 at a pressure of P1. At this time, the fourth three-way valve 14 is opened. #, 3 # The pure SF6 gas in the piston-type SF6 gas power chamber 6 is injected into the chromatographic column separation device 1 at a pressure P1, pushing the SF6 sample gas in the device to complete the separation.

[0037] 3) The thermal conductivity detector 2 detects the thermal conductivity of the gas separated by the chromatographic column separation device 1, and determines the SF6 purity of the gas at the outlet of the chromatographic column separation device 1 by comparing it with the thermal conductivity of pure SF6; when the gas flowing through the thermal conductivity detector 2 is pure SF6 gas, the fifth three-way valve 15 is opened. # , 2 # The pure SF6 gas is injected into the piston-type SF6 buffer chamber 3 through the port; when the SF6 gas containing decomposition products flows through the thermal conductivity detector 2, the 1st of the fifth three-way valve 15 is opened. # , 3 # port, and 2 of the third three-way valve 13 # , 3 # The port is used to inject SF6 gas containing decomposition products into the piston-type decomposition product collecting chamber 4.

[0038] 4) After the process from step 1) to step 3), the decomposition products in the SF6 gas in the first round of sampling are separated and enriched and then temporarily stored in the piston-type decomposition product collection chamber 4; after the separation and enrichment of the first round of samples are completed, the fifth three-way valve 15 and the fourth three-way valve 14 are closed, and the sixth three-way valve 16 is opened. # , 3 # The pure SF6 gas in the piston-type SF6 buffer chamber 3 is injected into the piston-type SF6 gas power chamber 6, and the injection volume is V0, and then steps 1) to 3) are repeated to separate and enrich the next round of sampled gas. The required rounds of separation and enrichment are set according to the concentration range of the decomposition products in the sample gas and the detection accuracy of the decomposition product detector.

[0039] 5) After completing the set round of sample separation and enrichment, the separated and enriched high-concentration decomposition products are collected in the piston-type decomposition product collection chamber 4, and the separated pure SF6 gas is collected in the piston-type SF6 buffer chamber 3. When it is necessary to further concentrate the high-concentration decomposition product gas in the piston-type decomposition product collection chamber 4, open the second three-way valve 12. # , 3 # Port and 1 of the third three-way valve 13 # , 2 # port, close the fourth three-way valve 14, transfer the gas in the piston-type decomposition product collection chamber 4 to the piston-type gas premixing chamber 5, and then repeat steps 1) to 3) to separate and enrich, so that the concentration of the decomposition product is further increased.

[0040] 6) After the test is completed, open the first three-way valve 11# , 3 # port and the sixth three-way valve 16 # , 2 # port, close the fifth three-way valve 15, start the booster pump 10, and re-inject the pure SF6 gas in the piston-type SF6 buffer chamber 3 into the SF6 gas chamber of the device under test through the booster pump 10, so as to avoid the consumption of gas in the SF6 gas chamber of the device under test during sampling, maintain the insulation capacity of the device under test, and reduce the emission of SF6 tail gas.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas-enriched sulfur hexafluoride decomposition product on-site sampling device, characterized in that: include: A chromatographic column separation device (1), a thermal conductivity detector (2), a piston-type SF6 buffer chamber (3), a piston-type decomposition product collection chamber (4), a piston-type gas premixing chamber (5), a piston-type SF6 gas power chamber (6), a mass flow meter (9), a booster pump (10), a first three-way valve (11), a second three-way valve (12), a third three-way valve (13), a fourth three-way valve (14), a fifth three-way valve (15), and a sixth three-way valve (16); the first three-way valve (11) and the second three-way valve (12) are connected to the first three-way valve (11). # The port is sealedly connected to one end of the mass flow meter (9), and the other end of the mass flow meter (9) is sealed to one end of the second three-way valve (12). # Port seal connection, second three-way valve (12) 2 # Port 1 of the third three-way valve (13) # Port seal connection, third three-way valve (13) 2 # The port is sealedly connected to the piston-type decomposition product collection chamber (4), and the 3-way valve of the second three-way valve (12) is # Port 1 of the fourth three-way valve (14) # The piston-type gas premixing chamber (5) is sealed and connected to the 3-way valve (12). # Port 1 of the fourth three-way valve (14) # On the pipeline between the ports, the fourth three-way valve (14) # The port is sealed and connected to the input end of the chromatographic column separation device (1), the output end of the chromatographic column separation device (1) is sealed and connected to the input end of the thermal conductivity detector (2), and the output end of the thermal conductivity detector (2) is sealed and connected to the 1 end of the fifth three-way valve (15). # Port seal connection, fifth three-way valve (15) 2 # The port is sealed and connected to the piston-type SF6 buffer chamber (3). The 3 # Port 3 of the third three-way valve (13) # The piston-type SF6 gas power chamber (6) is sealed and connected to the 2 of the fourth three-way valve (14). # Port; 2 of the fourth three-way valve (14) # Port 3 of the sixth three-way valve (16) # The port is sealed and connected, and the input port of the boost pump (10) is connected to the 1st of the sixth three-way valve (16). # The ports are sealed and connected, and the output port of the booster pump (10) is connected to the 3-way port of the first three-way valve (11). # Port seal connection, 2 of the sixth three-way valve (16) # Port 2 of the fifth three-way valve (15) # Port sealing connection; The chromatographic column separation device (1) is used to separate the decomposition products and SF6 gas in the sampled gas; the piston-type SF6 buffer chamber (3) is used to collect the separated pure SF6 gas; the piston-type decomposition product collection chamber (4) is used to collect the decomposition product gas after separation and enrichment; the piston-type SF6 gas power chamber (6) is used to store quantitative pure SF6 and push the SF6 sample into the chromatographic column separation device (1) to complete the separation; the piston of the piston-type gas premixing chamber (5) and the piston-type SF6 gas power chamber (6) are used to provide a constant gas pressure; the mass flow meter (9) is used to measure the total amount of SF6 gas sample extracted from the SF6 gas chamber of the device to be tested; The sample gas sampled in the piston-type gas premixing chamber (5) is circulated and separated through the chromatographic column separation device (1), and the gas separated by the chromatographic column separation device (1) is detected by the thermal conductivity detector (2), and is respectively injected into the piston-type SF6 buffer chamber (3) and the piston-type decomposition product collection chamber (4) for enrichment. The sample gas is circulated, separated and enriched according to the concentration requirements of the detection gas.

2. The on-site sampling device for gas-enriched sulfur hexafluoride decomposition products according to claim 1, characterized in that: Also includes: The first pressure gauge (7) is sealed and connected to the 3 of the fourth three-way valve (14). # On the pipe between the port and the input end of the chromatographic column separation device (1).

3. The on-site sampling device for gas-enriched sulfur hexafluoride decomposition products according to claim 2, characterized in that: Also includes: The second pressure gauge (8) is sealed and connected to the 2 end of the sixth three-way valve (16). # Port 2 of the fifth three-way valve (15) # On the pipe between the ports.

4. A method using the on-site sampling device for gas-enriched sulfur hexafluoride decomposition products according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, sampling of sample gas; S2, primary separation of sample gas; S3, primary enrichment of sample gas; S4, cyclic separation and enrichment of sample gas; S5, refilling of SF6 gas; The chromatographic column separation device (1) is used to separate the decomposition products and SF6 gas in the sampled gas; the piston-type SF6 buffer chamber (3) is used to collect the separated pure SF6 gas; the piston-type decomposition product collection chamber (4) is used to collect the decomposition product gas after separation and enrichment; the piston-type SF6 gas power chamber (6) is used to store quantitative pure SF6 and push the SF6 sample into the chromatographic column separation device (1) to complete the separation; the piston of the piston-type gas premixing chamber (5) and the piston-type SF6 gas power chamber (6) are used to provide a constant gas pressure; the mass flow meter (9) is used to measure the total amount of SF6 gas sample extracted from the SF6 gas chamber of the device to be tested; The sample gas sampled in the piston-type gas premixing chamber (5) is circulated and separated through the chromatographic column separation device (1), and the gas separated by the chromatographic column separation device (1) is detected by the thermal conductivity detector (2), and is respectively injected into the piston-type SF6 buffer chamber (3) and the piston-type decomposition product collection chamber (4) for enrichment. The sample gas is circulated, separated and enriched according to the concentration requirements of the detection gas.

5. The method according to claim 4, characterized in that The method for sampling the sample gas in step S1 is as follows: 1 of the first three-way valve (11) is closed. # After the port is sealed and connected to the SF6 gas chamber of the device under test, open the first three-way valve (11) # , 2 # port and the second three-way valve (12) # , 3 # The SF6 sample gas is drawn from the SF6 gas chamber of the device to be tested and injected into the piston-type gas premixing chamber (5), and the amount of the sampled SF6 gas is recorded by a mass flow meter (9).

6. The method according to claim 5, characterized in that The method for primary separation of the sample gas in step S2 is as follows: Open the fourth three-way valve (14) # , 3 # The piston is pushed to inject all the SF6 sample gas in the piston-type gas premixing chamber (5) into the chromatographic column separation device (1) at a constant pressure, and then the fourth three-way valve (14) is opened. # , 3 # The pure SF6 gas in the piston-type SF6 gas power chamber (6) is injected into the chromatographic column separation device (1) at a constant pressure, pushing the SF6 sample gas to complete a separation.

7. The method according to claim 6, characterized in that The method for primary enrichment of the sample gas in step S3 is as follows: the thermal conductivity detector (2) detects the thermal conductivity of the gas separated by the chromatographic column separation device (1); when the gas flowing through the thermal conductivity detector (2) is pure SF6 gas, the fifth three-way valve (15) is opened. # , 2 # The pure SF6 gas is injected into the piston-type SF6 buffer chamber (3) through the port; when the gas flowing through the thermal conductivity detector (2) is SF6 gas containing decomposition products, the fifth three-way valve (15) is opened. # , 3 # Port 2 and the third three-way valve (13) # , 3 # The SF6 gas containing the decomposition products is injected into the piston-type decomposition product collecting chamber (4) for primary enrichment.

8. The method according to claim 7, characterized in that The method for circulating separation and enrichment of the sample gas in step S4 is as follows: close the fifth three-way valve (15) and the fourth three-way valve (14), open the sixth three-way valve (16) # , 3 # The port is used to inject a certain volume of pure SF6 gas in the piston-type SF6 buffer chamber (3) into the piston-type SF6 gas power chamber (6); the second three-way valve (12) is opened. # , 3 # port and the third three-way valve (13) # , 2 # port, close the fourth three-way valve (14), transfer the gas in the piston-type decomposition product collection chamber (4) to the piston-type gas premixing chamber (5), and then repeat steps S1 to S3 for cyclic separation and enrichment.

9. The method according to claim 8, characterized in that The method for recharging SF6 gas in step S5 is as follows: Open the first three-way valve (11) # , 3 # Port 1 and the sixth three-way valve (16) # , 2 # The fifth three-way valve (15) is closed, and the booster pump (10) is started to inject the pure SF6 gas in the piston-type SF6 buffer chamber (3) into the SF6 gas chamber of the device under test through the booster pump (10).

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