A dissolved gas analysis system in oil and its headspace degassing method and cleaning method

Abstract

The invention relates to a dissolved gas analysis system in oil, a vacuum isochoric headspace degassing method using the system and a cleaning method of the system. The dissolved gas analysis system in oil comprises an oil inlet, an oil pump, a degassing chamber, an oil cylinder, a stepping motor, an oil remover, an air pump, a vacuum pump, a six-way valve, a chromatographic detector and a carrier gas interface; the oil inlet comprises a transformer oil inlet and a syringe oil inlet, thereby realizing online and offline dual-mode switching measurement; the vacuum isochoric headspace degassing realizes the completion of headspace degassing under the lowest pressure condition, thereby achieving the highest degassing efficiency; the invention also proposes an efficient deep cleaning method, which realizes rapid and efficient cleaning through dynamic pressure changes and high vacuum elution, so that the oil sample concentration can respond quickly when switching from high to low, thereby significantly improving the accuracy and real-time performance of the detection.

Description

Technical Field

[0001] The invention relates to the technical field of chromatograph detection, and in particular to an oil-dissolved gas analysis system and a headspace degassing method and a cleaning method thereof. Background Art

[0002] Laboratory chromatography detection is currently one of the main methods for analyzing dissolved gases in oil. This method requires the collected oil samples to be brought back to the laboratory, and then the dissolved gases are separated from the oil using an oil-gas separation device. Then, a gas chromatograph is used to separate and detect each gas component, and finally the content of dissolved gas components in the oil is calculated. Since this method requires the oil samples to be brought back to the laboratory for testing, the entire testing process is time-consuming and cannot reflect the operating status of the equipment in a timely manner. In addition, the laboratory chromatography detection method involves multiple steps, including oil sample collection, transportation, processing, testing, etc., and the operation process is relatively cumbersome.

[0003] With the development of technology, online detection of dissolved gas in transformer oil has gradually been applied. This method monitors the composition and content of dissolved gas in oil in real time by connecting an online dissolved gas analyzer in oil to the transformer. Such devices are generally large in size and weight, require fixed installation, are expensive, and have high operating and maintenance costs. Moreover, such devices are inevitably prone to errors after long-term use. At this time, it is necessary to configure oil samples from the laboratory to calibrate the online device. The oil samples need to be configured in the laboratory to test the concentration of each component, and then transported to the site. There are inconsistencies with laboratory data due to transportation and long storage time, which makes the calibration results invalid.

[0004] In addition, in the prior art, the headspace degassing method is used to separate dissolved gases from oil. However, the headspace degassing is performed under atmospheric pressure or low vacuum. Air is inevitably introduced during the execution process, which reduces the degassing vacuum and causes a decrease in the degassing rate. At the same time, the methane and carbon dioxide content in the air will affect the data analysis. In addition, the existing device cannot respond in time when the oil sample concentration is switched from high to low. Since the high-concentration oil sample remains in the degassing circuit, the residual high-concentration oil sample in the previous transaction affects the accuracy of the data when switching to the low-concentration oil sample. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a dissolved gas in oil analysis system, a headspace degassing method for a dissolved gas in oil analysis system, and a cleaning method for a dissolved gas in oil analysis system to solve the above problems.

[0006] The present invention provides the following technical solutions:

[0007] A system for analyzing dissolved gas in oil, comprising an oil inlet, an oil pump, a degassing chamber, an oil cylinder, a stepper motor, an oil remover, an air pump, a vacuum pump, a six-way valve, a chromatographic detector and a carrier gas interface; the oil inlet comprises a transformer oil inlet and a syringe oil inlet; the transformer oil inlet is connected to the oil pump through a switch valve V1, and the syringe oil inlet is connected to the oil pump through a switch valve V7; the oil pump is connected to the oil cylinder through a switch valve V9, the oil cylinder is marked with upper and lower limit marks, and the oil cylinder is connected to the stepper motor; the transformer oil inlet, the switch valve V1, the oil pump, the degassing chamber, the switch valve V2, and the transformer oil return port are sequentially connected to form a transformer circulating oil circuit; the syringe oil inlet, the switch valve V7, the oil pump, the switch valve V9, the switch valve V6, and the waste oil bag oil return port are sequentially connected to form a syringe circulating oil circuit; the degassing chamber is provided with a magnetic stirrer and a heating device, and the degassing chamber A liquid level detector is provided at the upper part, and the gas in the degassing chamber passes through the switch valve V3, the degreaser, the liquid level switch, the pressure sensor, the air pump, the switch valve V4, the six-way valve, the switch valve V8 and the current limiting tube in sequence and then returns to the degassing chamber to form a degassing circuit; the vacuum pump is connected between the air pump and the switch valve V4 through the switch valve V5; one end of the switch valve V10 is connected to the six-way valve and is connected in parallel with the switch valve V8, and the other end is connected to the liquid level switch; the carrier gas passes through the carrier gas interface, the switch valve V12, the six-way valve and the chromatographic detector in sequence to form a detection circuit; a quantitative tube is provided in the six-way valve, and the six-way valve has two states, A and B, wherein, when the six-way valve is in state A, the quantitative tube is connected to the switch valve V4, the switch valve V10 and the switch valve V8, and is connected to the degassing circuit, and when the six-way valve is in state B, the quantitative tube is connected to the switch valve V12 and the chromatographic detector, and is connected to the detection circuit.

[0008] The present invention also discloses a headspace degassing method for a dissolved gas in oil analysis system. The headspace degassing method is performed by using the aforementioned dissolved gas in oil analysis system, and the six-way valve is initialized to state A. The method comprises the following steps:

[0009] Step S1, oil return, oil cylinder reset: if the oil cylinder is at the lower limit position, execute step S2; if the oil cylinder is not at the lower limit position, perform the oil cylinder reset operation;

[0010] Step S2, oil intake;

[0011] Step S3, oil heating: start oil heating, heat the oil to 50°C and keep the temperature constant for 1 minute, during which the switch valve V2 is periodically opened for 3 seconds every 15 seconds, and when the heating is stopped, the switch valve V2 is closed;

[0012] Step S4, vacuuming: open the switch valves V4, V5, V10, the air pump, and the vacuum pump, and vacuumize to -98 kPa. After a delay of 10 seconds, close the switch valves V4, V5, V10, the air pump, and the vacuum pump;

[0013] Step S5, vacuum isochoric headspace degassing: open the switch valve V9, and after the oil cylinder is pulled up by 40 mL, close the switch valve V9; then, open the switch valves V3, V4, V8, and the air pump, and the degassing chamber starts to stir to form a loop; after 10 minutes, turn off the stirring, the air pump and the switch valves V3, V4, and V8;

[0014] Step S6, sample gas injection: during injection, the six-way valve is switched to state B; after injection, the six-way valve is switched back to state A;

[0015] Step S7, the oil cylinder is reset.

[0016] Furthermore, the oil cylinder resetting operation in step S1 includes the following steps:

[0017] Step S11, open the switch valve V9, pull the oil cylinder upward by 10mL, extract the oil sample, and leave space in the upper part of the degassing chamber 1 for vacuuming;

[0018] Step S12, vacuuming: open the switch valves V3, V4, V5, and V10, turn on the air pump and vacuum pump, reduce the pressure to -98 kPa, delay for 10 seconds, turn off the air pump and vacuum pump, and close the switch valves V3, V4, V5, and V10;

[0019] Step S13, oil return: when in the transformer oil inlet mode, open the switch valve V2, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V2; when in the syringe oil inlet mode, close the switch valve V9, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V6.

[0020] Furthermore, the oil inletting in step S2 includes the following steps: when in the transformer oil inletting mode: open the switch valves V1, V2, and the oil pump, and after the oil circulates for 2 minutes, close the switch valves V1, V2, and the oil pump; when in the injector oil inletting mode: open the switch valves V6, V7, V9, and the oil pump, and feed the oil for 30 seconds, and close the switch valves V6 and V9; then, open the switch valve V3, wait until the oil level reaches the level detector, and close the switch valves V3, V7, and the oil pump.

[0021] Further, the oil cylinder resetting in step S7 includes the following steps:

[0022] Step S71, open the switch valves V3, V4, V5, and V10. After 30 seconds, turn on the air pump and vacuum pump, and the pressure drops to -98 kPa. After a delay of 10 seconds, turn off the air pump and vacuum pump, and close the switch valves V3, V4, V5, and V10;

[0023] Step S72, oil return to the oil cylinder: when in transformer oil inlet mode: open the switch valve V2, push the oil cylinder down 40mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V2;

[0024] When in the injector oil inlet mode: open the switch valve V6, push the oil cylinder down 40mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V6;

[0025] Step S73, oil return to the degassing chamber: when in the syringe oil inlet mode: open the switch valve V9, pull the oil cylinder up 50mL, close the switch valve V9, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat step S73 3 times to drain the oil in the degassing chamber.

[0026] The present invention also discloses a cleaning method for a dissolved gas in oil analysis system, which is applied to the aforementioned dissolved gas in oil analysis system and comprises the following steps:

[0027] Step S1, initializing the six-way valve to state A;

[0028] Step S2, vacuuming: open the switch valves V3, V4, V5, and V10, turn on the air pump and the vacuum pump, and reduce the pressure to -98 kPa. After a delay of 10 seconds, close the switch valves V3, V4, V5, V10, the air pump, and the vacuum pump;

[0029] Step S3, oil return: open the switch valve V9, after the oil cylinder is pulled up 50mL, close the switch valve V9; then, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat 3 times;

[0030] Step S4, oil inlet: open the switch valve V1 or V7 and the oil pump, and after 30 seconds of oil inlet, close the switch valve V1 or V7 and the oil pump;

[0031] Step S5, oil cleaning: open the switch valve V9, pull the oil cylinder upward by 50mL, wait for 10 seconds, push the oil cylinder downward by 50mL, repeat 3 times, and close the switch valve V9;

[0032] Step S6, oil return: open the switch valve V9, after the oil cylinder is pulled up 50mL, close the switch valve V9; then, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat 3 times;

[0033] Step S7, carrier gas cleaning: open the switch valves V3, V4, V8, and V10, then open the switch valves V11 and V12, wait for 5 seconds, and then close the switch valve V11; during the operation, the switch valve V12 is normally open;

[0034] Step S8, vacuum cleaning: open the switch valve V5, air pump, and vacuum pump, and the pressure drops to -98kPa. After a delay of 10 seconds, close the switch valves V3, V4, V5, V8, V10, air pump, and vacuum pump.

[0035] The present invention has the following beneficial technical effects:

[0036] 1. The present invention is designed with dual oil inlets, including two oil inlet modes, transformer and injector, to realize online and offline dual-mode switching measurement. It is not only suitable for rapid review of on-site data, but also can be used as an online monitoring device in emergency situations, which significantly improves the flexibility of operation and scope of application.

[0037] 2. The present invention provides a vacuum isochoric headspace degassing technology, which can completely evacuate the air in the degassing chamber and ensure that the headspace degassing is completed under the lowest pressure conditions, thereby achieving the highest degassing efficiency. At the same time, this technology eliminates the mixing of air during the degassing process, avoids the influence of methane and carbon dioxide gases in the air on the measurement, and improves the stability of degassing.

[0038] 3. The present invention adopts efficient cleaning technology to achieve fast and efficient cleaning through dynamic pressure changes and high vacuum elution, so that the oil sample can respond quickly when switching from high to low, thereby significantly improving the accuracy and real-time performance of the detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The diagram is a structural diagram of a system for analyzing dissolved gas in oil according to the present invention.

[0040] The reference numerals in the figure are:

[0041] 1. Degassing chamber; 2. Oil cylinder; 3. Stepper motor; 4. Liquid level detector; 5. Oil remover; 6. Liquid level switch; 7. Pressure sensor; 8. Vacuum pump; 9. Oil pump; 10. Flow limiting tube; 11. Air pump; 12. Chromatographic detector; 13. Carrier gas interface; 14. Six-way valve; 15. Transformer oil inlet; 16. Injector oil inlet; 17. Transformer oil return port; 18. Waste oil bag oil return port; 19. Magnetic stirrer. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0043] Embodiment 1

[0044] The present embodiment discloses a system for analyzing dissolved gas in oil, including an oil inlet, an oil pump 9, a degassing chamber 1, an oil cylinder 2, a stepping motor 3, an oil remover 5, an air pump 11, a vacuum pump 8, a six-way valve 14, a chromatographic detector 12, and a carrier gas interface 13; the oil inlet includes a transformer oil inlet 15 and a syringe oil inlet 16; the transformer oil inlet 15 is connected to the oil pump 9 through a switch valve V1, and the syringe oil inlet 16 is connected to the oil pump 9 through a switch valve V7; the oil pump 9 is connected to the oil pump 9 through a switch valve V8; the oil pump 9 is connected to the oil pump 9 through a switch valve V9; the oil pump 9 is connected to the oil pump 9 through a switch valve V1; the oil pump 9 is connected to the oil pump 9 through a switch valve V7; the oil pump 9 is connected to the oil pump 9 through a switch valve V8; the oil pump 9 is connected to the oil pump 9 through a switch valve V9; the oil pump 9 is connected to the oil pump 9 through a switch valve V1; the oil pump 9 is connected to the oil pump 9 through a switch valve V8 ... The switch valve V9 is connected to the oil cylinder 2, and the oil cylinder 2 is marked with upper and lower limit marks. The oil cylinder 2 is connected to the stepper motor 3 and is controlled by the stepper motor 3; the degassing chamber 1 is provided with a magnetic stirrer 19 and a heating device, and the transformer oil inlet 15, the switch valve V1, the oil pump 9, the degassing chamber 1, and the transformer oil return port 17 form a transformer circulating oil circuit; the injector oil inlet 16, the switch valve V7, the oil pump 9, the switch valve V9, the switch valve V6, and the waste oil bag oil return port 18 form an injector circulating oil circuit; A liquid level detector 4 is provided on the upper part of the degassing chamber 1. The gas in the degassing chamber 1 passes through the switch valve V3, the degreaser 5, the liquid level switch 6, the pressure sensor 7, the air pump 11, the switch valve V4, the six-way valve 14, the switch valve V8, and the current limiting tube 10 in sequence and then returns to the degassing chamber 1 to form a degassing circuit; the vacuum pump 8 is connected to the air pump 11 and the switch valve V4 through the switch valve V5; one end of the switch valve V10 is connected to the six-way valve and connected in parallel with the switch valve V8, and the other end is connected to the liquid level switch; the carrier gas is sequentially A detection circuit is formed by a carrier gas interface 13, a switch valve V12, a six-way valve 14 and a chromatographic detector 12; a quantitative tube is provided in the six-way valve 14, and the six-way valve 14 has two states, A and B, wherein when the six-way valve 14 is in state A, the quantitative tube is connected to the switch valve V4, the switch valve V10 and the switch valve V8, and is connected to the degassing circuit; and when the six-way valve 14 is in state B, the quantitative tube is connected to the switch valve V12, the chromatographic detector 12, and is connected to the detection circuit.

[0045] The system in this embodiment can realize online and offline dual-mode switching measurement, and can be used for rapid review of on-site data, and can also be used as an emergency online monitoring device.

[0046] This embodiment also discloses a headspace degassing method for a dissolved gas in oil analysis system. The headspace degassing method is performed using the aforementioned dissolved gas in oil analysis system, and the six-way valve is initialized to state A. The method comprises the following steps:

[0047] Step S1, oil return, oil cylinder 2 reset: if oil cylinder 2 is at the lower limit position, execute step S2; if oil cylinder 2 is not at the lower limit position, perform oil cylinder 2 reset operation;

[0048] Step S11, open the switch valve V9, pull the oil cylinder 2 upward by 10mL, extract the oil sample, and leave space in the upper part of the degassing chamber 1 for vacuuming;

[0049] Step S12, vacuuming: open the switch valves V3, V4, V5, and V10, turn on the air pump 11 and the vacuum pump 8, reduce the pressure to -98 kPa, delay for 10 seconds, turn off the air pump 11 and the vacuum pump 8, and close the switch valves V3, V4, V5, and V10;

[0050] Step S13, oil cylinder reset: when in transformer oil inlet mode, open the switch valve V2, push the oil cylinder 2 down 50mL, and after judging that the lower limit of the oil cylinder 2 is bright, close the switch valves V2 and V9; when in syringe oil inlet mode, close the switch valve V9, open the switch valve V6, push the oil cylinder 2 down 50mL, and after judging that the lower limit of the oil cylinder 2 is bright, close the switch valve V6.

[0051] Step S2, oil inlet: when in transformer oil inlet mode: open switch valves V1, V2, and oil pump 9, and after the oil circulates for 2 minutes, close switch valves V1, V2, and oil pump 9; when in injector oil inlet mode: open switch valves V6, V7, V9, and oil pump 9, and feed oil for 30 seconds, and close switch valves V6 and V9; then, open switch valve V3, wait until the oil level reaches the level detector 4, and close switch valves V3, V7, and oil pump 9.

[0052] Step S3, oil heating: start oil heating, heat the oil to 50°C and keep the temperature constant for 1 minute, during which the switch valve V2 is periodically opened for 3 seconds every 15 seconds, and when the heating is stopped, the switch valve V2 is closed;

[0053] Step S4, vacuuming: open the switch valves V4, V5, V10, the air pump 11, and the vacuum pump 8, and vacuumize to -98 kPa. After a delay of 10 seconds, close the switch valves V4, V5, V10, the air pump 11, and the vacuum pump 8;

[0054] Step S5, vacuum isochoric headspace degassing: open the switch valve V9, after the oil cylinder 2 is pulled up by 40 mL, close the switch valve V9; then, open the switch valves V3, V4, V8, and the air pump 11, and the degassing chamber 1 starts to stir to form a loop; after 10 minutes, turn off the stirring, and turn off the air pump 11, the switch valves V3, V4, and V8;

[0055] Step S6, sample gas injection: when injecting, the six-way valve is switched to the B state, the carrier gas enters from the carrier gas interface 13, passes through the switch valve V12 and the six-way valve 14, and enters the chromatographic detector 12; after the injection is completed, the six-way valve is switched back to the A state;

[0056] Step S7, oil cylinder 2 resets: Step S71, vacuuming: open switch valves V3, V4, V5, V10, turn on air pump 11, vacuum pump 8, the pressure drops to -98 kPa, delay 10 seconds, turn off air pump 11, vacuum pump 8, and close switch valves V3, V4, V5, V10;

[0057] Step S72, oil return to the oil cylinder: when in transformer oil inlet mode: open the switch valve V2, push the oil cylinder down 40mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V2;

[0058] When in the injector oil inlet mode: open the switch valve V6, push the oil cylinder down 40mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V6;

[0059] Step S73, oil return to the degassing chamber: when in the syringe oil inlet mode: open the switch valve V9, pull the oil cylinder up 50mL, close the switch valve V9, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat step S73 3 times to drain the oil in the degassing chamber.

[0060] This embodiment is a vacuum isochoric headspace degassing technology, which can completely evacuate the air in the degassing chamber, ensuring that the headspace degassing is completed under the lowest pressure conditions, thereby achieving the highest degassing efficiency. At the same time, this technology eliminates the influence of methane and carbon dioxide gases mixed in the air on the measurement, thereby improving the stability of degassing.

[0061] Embodiment 2

[0062] The present invention also discloses a cleaning method for a dissolved gas in oil analysis system, which is applied to the aforementioned dissolved gas in oil analysis system and comprises the following steps:

[0063] Step S1, initializing the six-way valve to state A;

[0064] Step S2, vacuuming: open the switch valves V3, V4, V5, and V10, turn on the air pump 11 and the vacuum pump 8, and the pressure drops to -98 kPa. After a delay of 10 seconds, close the switch valves V3, V4, V5, V10, the air pump 11, and the vacuum pump 8;

[0065] Step S3, oil return: open the switch valve V9, after the oil cylinder is pulled up 50mL, close the switch valve V9; then, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat 3 times;

[0066] Step S4, oil inlet: open the switch valve V1 or V7 and the oil pump 9, and after the oil inlet lasts for 30 seconds, close the switch valve V1 or V7 and the oil pump 9;

[0067] Step S5, oil cleaning: open the switch valve V9, pull the oil cylinder 2 upward by 50mL, wait for 10 seconds, push the oil cylinder 2 downward by 50mL, repeat 3 times, and close the switch valve V9;

[0068] Step S6, oil return: open the switch valve V9, after the oil cylinder is pulled up 50mL, close the switch valve V9; then, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat 3 times;

[0069] Step S7, carrier gas cleaning: open the switch valves V3, V4, V8, and V10, then open the switch valves V11 and V12, wait for 5 seconds, and then close the switch valve V11; during the operation, the switch valve V12 is normally open;

[0070] Step S8, vacuum cleaning: open the switch valve V5, air pump 11, and vacuum pump 8, and the pressure drops to -98 kPa. After a delay of 10 seconds, close the switch valves V3, V4, V5, V8, V10, air pump 11, and vacuum pump 8.

[0071] In this embodiment, the degassing chamber 1 is firstly rinsed with an oil sample to clean the residual oil, and then high-purity air is injected to flush the degassing chamber 1 and the air path, and then the degassing chamber 1 and the air path are evacuated. Rapid and efficient cleaning is achieved through dynamic pressure changes and high vacuum elution, so that the oil sample can respond quickly when switching from high to low, thereby significantly improving the accuracy and real-time performance of the detection.

[0072] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A system for analyzing dissolved gas in oil, characterized in that: It includes an oil inlet, an oil pump, a degassing chamber, an oil cylinder, a stepper motor, an oil remover, an air pump, a vacuum pump, a six-way valve, a chromatographic detector and a carrier gas interface; the oil inlet includes a transformer oil inlet and a syringe oil inlet; the transformer oil inlet is connected to the oil pump through a switch valve V1, and the syringe oil inlet is connected to the oil pump through a switch valve V7; the oil pump is connected to the oil cylinder through a switch valve V9, the oil cylinder is marked with upper and lower limit marks, and the oil cylinder is connected to the stepper motor; the transformer oil inlet, the switch valve V1, the oil pump, the degassing chamber, the switch valve V2, and the transformer oil return port are connected in sequence to form a transformer circulating oil circuit; the syringe oil inlet, the switch valve V7, the oil pump, the switch valve V9, the switch valve V6, and the waste oil bag oil return port are connected in sequence to form a syringe circulating oil circuit; the degassing chamber is provided with a magnetic stirrer and a heating device, and the upper part of the degassing chamber is provided with a liquid level detector The gas in the degassing chamber passes through the switch valve V3, the deoiler, the liquid level switch, the pressure sensor, the air pump, the switch valve V4, the six-way valve, the switch valve V8 and the current limiting tube in sequence and then returns to the degassing chamber to form a degassing circuit; the vacuum pump is connected between the air pump and the switch valve V4 through the switch valve V5; one end of the switch valve V10 is connected to the six-way valve and is connected in parallel with the switch valve V8, and the other end is connected to the liquid level switch; the carrier gas passes through the carrier gas interface, the switch valve V12, the six-way valve and the chromatographic detector in sequence to form a detection circuit; a quantitative tube is provided in the six-way valve, and the six-way valve has two states, A and B, wherein, when the six-way valve is in state A, the quantitative tube is connected to the switch valve V4, the switch valve V10 and the switch valve V8, and is connected to the degassing circuit, and when the six-way valve is in state B, the quantitative tube is connected to the switch valve V12 and the chromatographic detector, and is connected to the detection circuit.

2. A headspace degassing method for a dissolved gas analysis system in oil, characterized in that: A headspace degassing method is performed using the oil dissolved gas analysis system of claim 1, and the six-way valve is initialized to state A; the method comprises the following steps: Step S1, oil return, oil cylinder reset: if the oil cylinder is at the lower limit position, execute step S2; if the oil cylinder is not at the lower limit position, perform the oil cylinder reset operation; Step S2, oil intake; Step S3, oil heating: start oil heating, heat the oil to 50°C and keep the temperature constant for 1 minute, during which the switch valve V2 is periodically opened for 3 seconds every 15 seconds, and when the heating is stopped, the switch valve V2 is closed; Step S4, vacuuming: open the switch valves V4, V5, V10, the air pump, and the vacuum pump, and vacuumize to -98 kPa. After a delay of 10 seconds, close the switch valves V4, V5, V10, the air pump, and the vacuum pump; Step S5, vacuum isochoric headspace degassing: open the switch valve V9, and after the oil cylinder is pulled up by 40 mL, close the switch valve V9; then, open the switch valves V3, V4, V8, and the air pump, and the degassing chamber starts to stir to form a loop; after 10 minutes, turn off the stirring, the air pump and the switch valves V3, V4, and V8; Step S6, sample gas injection: during injection, the six-way valve is switched to state B; after injection, the six-way valve is switched back to state A; Step S7, the oil cylinder is reset.

3. The headspace degassing method of a dissolved gas analysis system in oil according to claim 2, characterized in that: The oil cylinder reset operation in step S1 includes the following steps: Step S11, open the switch valve V9, pull the oil cylinder upward by 10mL, extract the oil sample, and leave space in the upper part of the degassing chamber for vacuuming; Step S12, vacuuming: open the switch valves V3, V4, V5, and V10, turn on the air pump and vacuum pump, reduce the pressure to -98 kPa, delay for 10 seconds, turn off the air pump and vacuum pump, and close the switch valves V3, V4, V5, and V10; Step S13, oil cylinder reset: when in transformer oil inlet mode, open the switch valve V2, push the oil cylinder downward by 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valves V2 and V9; when in syringe oil inlet mode, close the switch valve V9, open the switch valve V6, push the oil cylinder downward by 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6.

4. The headspace degassing method of a dissolved gas analysis system in oil according to claim 2, characterized in that: The oil inlet in step S2 includes the following steps: when in the transformer oil inlet mode: open the switch valves V1, V2, and the oil pump, and after the oil circulates for 2 minutes, close the switch valves V1, V2, and the oil pump; when in the injector oil inlet mode: open the switch valves V6, V7, V9, and the oil pump, and feed the oil for 30 seconds, and close the switch valves V6 and V9; then, open the switch valve V3, wait until the oil level reaches the level detector, and close the switch valves V3, V7, and the oil pump.

5. The headspace degassing method of a dissolved gas analysis system in oil according to claim 2, characterized in that: The oil cylinder resetting in step S7 includes the following steps: Step S71, vacuuming: open the switch valves V3, V4, V5, and V10, turn on the air pump and vacuum pump, reduce the pressure to -98 kPa, delay for 10 seconds, turn off the air pump and vacuum pump, and close the switch valves V3, V4, V5, and V10; Step S72, oil return to the oil cylinder: when in transformer oil inlet mode: open the switch valve V2, push the oil cylinder down 40mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V2; When in the injector oil inlet mode: open the switch valve V6, push the oil cylinder down 40mL, and after judging that the lower limit of the oil cylinder is on, close the switch valve V6; Step S73, oil return to the degassing chamber: when in the syringe oil inlet mode: open the switch valve V9, pull the oil cylinder up 50mL, close the switch valve V9, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat step S73 3 times to drain the oil in the degassing chamber.

6. A method for cleaning a dissolved gas analysis system in oil, characterized in that: The system for analyzing dissolved gas in oil as claimed in claim 1 comprises the following steps: Step S1, initializing the six-way valve to state A; Step S2, vacuuming: open the switch valves V3, V4, V5, and V10, turn on the air pump and the vacuum pump, and reduce the pressure to -98 kPa. After a delay of 10 seconds, close the switch valves V3, V4, V5, V10, the air pump, and the vacuum pump; Step S3, oil return: open the switch valve V9, after the oil cylinder is pulled up 50mL, close the switch valve V9; then, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat 3 times; Step S4, oil inlet: open the switch valve V1 or V7 and the oil pump, and after 30 seconds of oil inlet, close the switch valve V1 or V7 and the oil pump; Step S5, oil cleaning: open the switch valve V9, pull the oil cylinder upward by 50mL, wait for 10 seconds, push the oil cylinder downward by 50mL, close the switch valve V9, and repeat 3 times; Step S6, oil return: open the switch valve V9, after the oil cylinder is pulled up 50mL, close the switch valve V9; then, open the switch valve V6, push the oil cylinder down 50mL, and after judging that the lower limit of the oil cylinder is bright, close the switch valve V6; repeat 3 times; Step S7, carrier gas cleaning: open the switch valves V3, V4, V8, and V10, then open the switch valves V11 and V12, wait for 5 seconds, and then close the switch valve V11; during the operation, the switch valve V12 is normally open; Step S8, vacuum cleaning: open the switch valve V5, air pump, and vacuum pump, and the pressure drops to -98 kPa. After a delay of 10 seconds, close the switch valves V3, V4, V5, V8, V10, air pump, and vacuum pump.

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