Device and method for purifying sulfur hexafluoride gas from sulfur hexafluoride mixed gas

Abstract

The device and method for purifying sulfur hexafluoride gas from sulfur hexafluoride mixed gas include a mixed gas exhaust pipeline, a buffer tank, a pressure regulating valve, a mass flow controller, a first adsorption column, a second adsorption column, a storage tank and a nitrogen exhaust pipeline; the present invention can achieve the purpose of continuous purification of SF6 gas through the alternating operation and regeneration of the first adsorption column and the second adsorption column. The function of the first sulfur hexafluoride sensor and the second sulfur hexafluoride sensor is to find the appropriate adsorption and regeneration time, so that the first adsorption column and the second adsorption column can achieve the SF6 content in the discharged N2 lower than the emission requirements specified in the relevant standards, and the concentration of the desorbed SF6 gas in the regenerated adsorption column is above 90%; the present invention has a novel design, a simple structure, and is easy to operate. It can purify the SF6 in the SF6 / N2 mixed gas in the GIS equipment to more than 90%, so that SF6 can be recycled and reused, saving the use of SF6 and reducing the operating cost.

Description

Technical Field

[0001] The invention belongs to the technical field of sulfur hexafluoride purification, and particularly relates to a device and a method for purifying sulfur hexafluoride gas from a sulfur hexafluoride mixed gas. Background Art

[0002] In order to save energy and reduce emissions, State Grid Corporation is looking for a method to reduce the amount of SF6 gas mixed in high-voltage switches. SF6 / N2 mixed gas is a transitional method to replace SF6 gas. By replacing a small number of components on existing GIS equipment, the existing GIS equipment can use SF6 / N2 mixed gas as an insulating medium. By replacing 30% SF6 / N2 mixed gas, a 220KV GIS device can save 60% of SF6 usage under the same application conditions, achieving the purpose of saving SF6 usage, reducing the amount of SF6 gas used from the source, and indirectly reducing the probability of SF6 gas leaking into space. The method of using pure SF6 gas for the recovery and treatment of 30% SF6 / N2 is obviously not feasible, so it is necessary to find a new device and method for purifying SF6 gas in 30% SF6 / N2 gas. Summary of the invention

[0003] In order to solve the deficiencies of the prior art, the present invention provides a device and method for purifying sulfur hexafluoride gas from a sulfur hexafluoride mixed gas, which has a scientific principle, is easy to operate, is safe and reliable, and has a high purification efficiency.

[0004] The present invention adopts the following technical scheme: a device for purifying sulfur hexafluoride gas from a sulfur hexafluoride mixed gas, comprising a mixed gas extraction pipeline, a buffer tank, a pressure regulating valve, a mass flow controller, a first adsorption column, a second adsorption column, a storage tank and a nitrogen exhaust pipeline;

[0005] The gas outlet of the mixed gas extraction pipeline is connected to the gas inlet of the buffer tank, a pressure sensor and a first solenoid valve are arranged on the mixed gas extraction pipeline along the airflow direction, the gas outlet of the buffer tank is connected to the gas inlet of the pressure stabilizing valve, the gas outlet of the pressure stabilizing valve is connected to the gas inlet of the mass flow controller, the gas outlet of the mass flow controller is connected to the first adsorption column through the first adsorption pipeline, the gas outlet of the mass flow controller is connected to the second adsorption column through the second adsorption pipeline, a second solenoid valve is arranged on the first adsorption pipeline, a third solenoid valve is arranged on the second adsorption pipeline, a first regeneration pipeline is connected on the gas outlet side of the second solenoid valve on the first adsorption pipeline and on the gas outlet side of the third solenoid valve on the second adsorption pipeline, a fourth solenoid valve and a fifth solenoid valve are arranged on the first regeneration pipeline, a second regeneration pipeline is connected between the first regeneration pipeline and the gas inlet of the storage tank, the connection position of the second regeneration pipeline and the first regeneration pipeline is located between the fourth solenoid valve and the fifth solenoid valve, and a first compressor and a first sulfur hexafluoride sensor are arranged in sequence on the second regeneration pipeline along the airflow direction;

[0006] The gas outlet of the first adsorption column is connected to the first exhaust pipe, the gas outlet of the second adsorption column is connected to the second exhaust pipe, the first exhaust pipe is provided with a sixth solenoid valve, the second exhaust pipe is provided with a seventh solenoid valve, the gas outlet of the first exhaust pipe and the gas outlet of the second exhaust pipe are both connected to the gas inlet of the nitrogen exhaust pipeline, and the nitrogen exhaust pipeline is provided with a second sulfur hexafluoride sensor.

[0007] A pressurized air extraction pipeline is connected between the air inlet side and the air outlet side of the first solenoid valve, and an eighth solenoid valve and a second compressor are sequentially arranged along the pressurized air extraction pipeline in the air flow direction.

[0008] The method for purifying sulfur hexafluoride gas from a sulfur hexafluoride mixed gas comprises the following steps:

[0009] (1) Connect the air inlet of the mixed gas extraction pipeline to the air outlet of the GIS equipment;

[0010] (2) When the pressure sensor detects that the pressure of the SF6 / N2 mixed gas with a sulfur hexafluoride concentration of 30% in the GIS equipment is P>0.35Mpa, the first solenoid valve opens, the eighth solenoid valve closes, and the mixed gas enters the buffer tank through the mixed gas extraction pipeline; when the pressure of the mixed gas is P<0.35Mpa, the eighth solenoid valve opens, the first solenoid valve closes, and the second compressor starts to extract the SF6 / N2 mixed gas in the GIS equipment into the buffer tank;

[0011] (3) The mixed gas in the buffer tank passes through a large-flow pressure-stabilizing valve to stabilize the pressure to 0.3 MPa, which meets the normal working pressure of the mass flow controller. The flow rate of the mixed gas passing through is controlled by controlling the mass flow controller;

[0012] (4) The adsorbent in the first adsorption column adsorbs sulfur hexafluoride gas, and the nitrogen in the first adsorption column is discharged into the atmosphere through the nitrogen exhaust pipeline, while the second adsorption column waits;

[0013] (5) After the adsorbent in the first adsorption column adsorbs sulfur hexafluoride gas for a period of time, the adsorption stops and turns to regeneration. The adsorbed sulfur hexafluoride is stored in a storage tank. At the same time, the second adsorption column adsorbs sulfur hexafluoride gas, and the nitrogen in the second adsorption column is discharged into the atmosphere through the nitrogen exhaust pipeline;

[0014] (6) After the adsorbent in the second adsorption column adsorbs sulfur hexafluoride gas for a period of time, the adsorption stops and turns to regeneration. The adsorbed sulfur hexafluoride is stored in the storage tank. At the same time, the first adsorption column adsorbs sulfur hexafluoride gas, and the nitrogen in the first adsorption column is discharged into the atmosphere through the nitrogen exhaust pipeline;

[0015] (7) Repeat steps (5) and (6) until the SF6 / N2 mixed gas in the GIS equipment is completely exhausted.

[0016] The mass flow controller controls the flow rate of the mixed gas to 50-100 L / min.

[0017] The process of step (4) is specifically as follows: the second solenoid valve and the sixth solenoid valve are opened, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve and the seventh solenoid valve are closed, the first compressor is turned off, the SF6 / N2 mixed gas adsorbs SF6 gas through the adsorbent in the first adsorption column, and when the second sulfur hexafluoride sensor monitors that the SF6 content in N2 is lower than the emission requirements specified in the relevant standards, the N2 in the first adsorption column is discharged into the air through the first exhaust pipe and the nitrogen exhaust pipeline.

[0018] The process of step (5) is specifically as follows: the second solenoid valve, the fifth solenoid valve and the sixth solenoid valve are closed, the third solenoid valve and the seventh solenoid valve are opened, the sulfur hexafluoride gas in the mixed gas is adsorbed by the adsorbent in the second adsorption column, and when the second sulfur hexafluoride sensor detects that the SF6 content in the N2 is lower than the emission requirements specified in the relevant standards, the N2 in the second adsorption column is discharged into the air through the second exhaust pipe and the nitrogen exhaust pipeline; at the same time, the first adsorption column is regenerated, the fourth solenoid valve is opened, the first compressor is started, and the SF6 adsorbed in the first adsorption column is extracted into the storage tank, and the first sulfur hexafluoride sensor detects the purity of the SF6 extracted into the storage tank. The above-mentioned desorption method can make the SF6 gas concentration above 90%.

[0019] The process of step (6) is specifically as follows: the second solenoid valve and the sixth solenoid valve are opened, the third solenoid valve, the fourth solenoid valve and the seventh solenoid valve are closed, the SF6 / N2 mixed gas adsorbs SF6 gas through the adsorbent in the first adsorption column, and when the second sulfur hexafluoride sensor detects that the SF6 content in N2 is lower than the emission requirements specified in the relevant standards, the N2 in the first adsorption column is discharged into the air through the first exhaust pipe and the nitrogen exhaust pipeline; at the same time, the second adsorption column is regenerated, the fifth solenoid valve is opened, the first compressor is started, and the SF6 adsorbed in the second adsorption column is extracted into the storage tank, and the first sulfur hexafluoride sensor detects the purity of the SF6 extracted into the storage tank. The above-mentioned adsorption and desorption method can make the SF6 gas concentration above 90%.

[0020] By adopting the above technical solution, the present invention can achieve the purpose of continuously purifying SF6 gas through the alternating operation and regeneration of the first adsorption column and the second adsorption column. The function of the first sulfur hexafluoride sensor and the second sulfur hexafluoride sensor is to find a suitable adsorption and regeneration time, so that the first adsorption column and the second adsorption column can achieve the SF6 content in the discharged N2 lower than the emission requirements specified in the relevant standards, and the concentration of the desorbed SF6 gas in the regenerated adsorption column can be above 90%.

[0021] The present invention has novel design, simple structure and is easy to operate. It can purify SF6 in SF6 / N2 mixed gas in GIS equipment to more than 90%, so that SF6 can be recycled and reused, saving SF6 usage and reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0023] like Figure 1 As shown, the device for purifying sulfur hexafluoride gas from sulfur hexafluoride mixed gas of the present invention comprises a mixed gas extraction pipeline 1, a buffer tank 2, a pressure regulating valve 3, a mass flow controller 4, a first adsorption column 5, a second adsorption column 6, a storage tank 7 and a nitrogen exhaust pipeline 8;

[0024] The gas outlet of the mixed gas extraction pipeline 1 is connected to the gas inlet of the buffer tank 2, and a pressure sensor 9 and a first solenoid valve 10 are arranged on the mixed gas extraction pipeline 1 along the air flow direction. The gas outlet of the buffer tank 2 is connected to the gas inlet of the pressure regulating valve 3, and the gas outlet of the pressure regulating valve 3 is connected to the gas inlet of the mass flow controller 4. The gas outlet of the mass flow controller 4 is connected to the first adsorption column 5 through the first adsorption pipeline 11, and the gas outlet of the mass flow controller 4 is connected to the second adsorption column 6 through the second adsorption pipeline 12. The first adsorption pipeline 11 is provided with a second solenoid valve 13, and the second adsorption pipeline 12 is provided with a third solenoid valve 14. A magnetic valve 14, a first regeneration pipeline 15 is connected on the first adsorption pipeline 11 at the gas outlet side of the second solenoid valve 13 and on the second adsorption pipeline 12 at the gas outlet side of the third solenoid valve 14, a fourth solenoid valve 16 and a fifth solenoid valve 17 are arranged on the first regeneration pipeline 15, a second regeneration pipeline 18 is connected between the first regeneration pipeline 15 and the gas inlet of the storage tank 7, a connection position of the second regeneration pipeline 18 and the first regeneration pipeline 15 is located between the fourth solenoid valve 16 and the fifth solenoid valve 17, and a first compressor 19 and a first sulfur hexafluoride sensor 20 are arranged in sequence on the second regeneration pipeline 18 along the air flow direction;

[0025] The gas outlet of the first adsorption column 5 is connected to the first exhaust pipe 21, the gas outlet of the second adsorption column 6 is connected to the second exhaust pipe 22, the first exhaust pipe 21 is provided with a sixth solenoid valve 23, the second exhaust pipe 22 is provided with a seventh solenoid valve 24, the gas outlet of the first exhaust pipe 21 and the gas outlet of the second exhaust pipe 22 are both connected to the gas inlet of the nitrogen exhaust pipeline 8, and the nitrogen exhaust pipeline 8 is provided with a second sulfur hexafluoride sensor 25.

[0026] A pressurized air extraction pipeline 26 is connected between the air inlet side and the air outlet side of the first solenoid valve 10 , and an eighth solenoid valve 27 and a second compressor 28 are sequentially arranged on the pressurized air extraction pipeline 26 along the air flow direction.

[0027] The method for purifying sulfur hexafluoride gas from a sulfur hexafluoride mixed gas comprises the following steps:

[0028] (1) Connect the air inlet of the mixed gas extraction pipeline 1 to the air outlet of the GIS equipment 29;

[0029] (2) When the pressure sensor 9 detects that the pressure P of the SF6 / N2 mixed gas with a sulfur hexafluoride concentration of 30% in the GIS equipment 29 is greater than 0.35Mpa, the first solenoid valve 10 is opened, the eighth solenoid valve 27 is closed, and the mixed gas enters the buffer tank 2 through the mixed gas extraction pipeline 1; when the pressure P of the mixed gas is less than 0.35Mpa, the eighth solenoid valve 27 is opened, the first solenoid valve 10 is closed, and the second compressor 28 is started to extract the SF6 / N2 mixed gas in the GIS equipment 29 into the buffer tank 2;

[0030] (3) The mixed gas in the buffer tank 2 passes through the large-flow pressure-stabilizing valve 3 to stabilize the pressure to 0.3 MPa, which meets the normal working pressure of the mass flow controller 4. The flow rate of the mixed gas passing through is controlled by controlling the mass flow controller 4;

[0031] (4) The adsorbent in the first adsorption column 5 adsorbs the sulfur hexafluoride gas, and the nitrogen in the first adsorption column 5 is discharged into the atmosphere through the nitrogen exhaust pipeline 8, while the second adsorption column 6 waits;

[0032] (5) After the adsorbent in the first adsorption column 5 adsorbs sulfur hexafluoride gas for a period of time, the adsorption stops and turns to regeneration. The adsorbed sulfur hexafluoride is stored in the storage tank 7. At the same time, the second adsorption column 6 adsorbs sulfur hexafluoride gas. The nitrogen in the second adsorption column 6 is discharged into the atmosphere through the nitrogen exhaust pipeline 8;

[0033] (6) After the adsorbent in the second adsorption column 6 adsorbs the sulfur hexafluoride gas for a period of time, the adsorption stops and turns to regeneration. The adsorbed sulfur hexafluoride is stored in the storage tank 7. At the same time, the first adsorption column 5 adsorbs the sulfur hexafluoride gas, and the nitrogen in the first adsorption column 5 is discharged into the atmosphere through the nitrogen exhaust pipeline 8;

[0034] (7) Repeat steps (5) and (6) until the SF6 / N2 mixed gas in the GIS equipment 29 is completely exhausted.

[0035] The mass flow controller 4 controls the flow rate of the mixed gas to be 50-100 L / min.

[0036] The process of step (4) is specifically as follows: the second solenoid valve 13 and the sixth solenoid valve 23 are opened, the third solenoid valve 14, the fourth solenoid valve 16, the fifth solenoid valve 17 and the seventh solenoid valve 24 are closed, the first compressor 19 is turned off, the SF6 / N2 mixed gas adsorbs SF6 gas through the adsorbent in the first adsorption column 5, and when the second sulfur hexafluoride sensor 25 detects that the SF6 content in N2 is lower than the emission requirements specified in the relevant standards, the N2 in the first adsorption column 5 is discharged into the air through the first exhaust pipe 21 and the nitrogen exhaust pipeline 8.

[0037] The process of step (5) is specifically as follows: the second solenoid valve 13, the fifth solenoid valve 17 and the sixth solenoid valve 23 are closed, the third solenoid valve 14 and the seventh solenoid valve 24 are opened, the sulfur hexafluoride gas in the mixed gas is adsorbed by the adsorbent in the second adsorption column 6, and when the second sulfur hexafluoride sensor 25 detects that the SF6 content in the N2 is lower than the emission requirements specified in the relevant standards, the N2 in the second adsorption column 6 is discharged into the air through the second exhaust pipe 22 and the nitrogen exhaust pipeline 8; at the same time, the first adsorption column 5 is regenerated, the fourth solenoid valve 16 is opened, the first compressor 19 is started, and the SF6 adsorbed in the first adsorption column 5 is extracted into the storage tank 7. The first sulfur hexafluoride sensor 20 detects the purity of the SF6 extracted into the storage tank 7. The above-mentioned adsorption and desorption method can make the SF6 gas concentration above 90%.

[0038] The process of step (6) is specifically as follows: the second solenoid valve 13 and the sixth solenoid valve 23 are opened, the third solenoid valve 14, the fourth solenoid valve 16 and the seventh solenoid valve 24 are closed, the SF6 / N2 mixed gas adsorbs SF6 gas through the adsorbent in the first adsorption column 5, and when the second sulfur hexafluoride sensor 25 detects that the SF6 content in N2 is lower than the emission requirements specified in the relevant standards, the N2 in the first adsorption column 5 is discharged into the air through the first exhaust pipe 21 and the nitrogen exhaust pipeline 8; at the same time, the second adsorption column 6 is regenerated, the fifth solenoid valve 17 is opened, the first compressor 19 is started, and the SF6 adsorbed in the second adsorption column 6 is extracted into the storage tank 7, and the first sulfur hexafluoride sensor 20 detects the purity of the SF6 extracted into the storage tank 7. The above-mentioned adsorption and desorption method can make the SF6 gas concentration above 90%.

[0039] This embodiment does not impose any formal limitation on the shape, material, structure, etc. of the present invention. Any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for purifying sulfur hexafluoride gas from a sulfur hexafluoride mixed gas, which is operated by using a device for purifying sulfur hexafluoride gas from a sulfur hexafluoride mixed gas, characterized in that: The device for purifying sulfur hexafluoride gas from sulfur hexafluoride mixed gas comprises a mixed gas extraction pipeline, a buffer tank, a pressure regulating valve, a mass flow controller, a first adsorption column, a second adsorption column, a storage tank and a nitrogen exhaust pipeline; The gas outlet of the mixed gas extraction pipeline is connected to the gas inlet of the buffer tank, a pressure sensor and a first solenoid valve are arranged on the mixed gas extraction pipeline along the airflow direction, the gas outlet of the buffer tank is connected to the gas inlet of the pressure stabilizing valve, the gas outlet of the pressure stabilizing valve is connected to the gas inlet of the mass flow controller, the gas outlet of the mass flow controller is connected to the first adsorption column through the first adsorption pipeline, the gas outlet of the mass flow controller is connected to the second adsorption column through the second adsorption pipeline, a second solenoid valve is arranged on the first adsorption pipeline, a third solenoid valve is arranged on the second adsorption pipeline, a first regeneration pipeline is connected on the gas outlet side of the second solenoid valve on the first adsorption pipeline and on the gas outlet side of the third solenoid valve on the second adsorption pipeline, a fourth solenoid valve and a fifth solenoid valve are arranged on the first regeneration pipeline, a second regeneration pipeline is connected between the first regeneration pipeline and the gas inlet of the storage tank, the connection position of the second regeneration pipeline and the first regeneration pipeline is located between the fourth solenoid valve and the fifth solenoid valve, and a first compressor and a first sulfur hexafluoride sensor are arranged in sequence on the second regeneration pipeline along the airflow direction; The gas outlet of the first adsorption column is connected to the first exhaust pipe, the gas outlet of the second adsorption column is connected to the second exhaust pipe, the first exhaust pipe is provided with a sixth solenoid valve, the second exhaust pipe is provided with a seventh solenoid valve, the gas outlet of the first exhaust pipe and the gas outlet of the second exhaust pipe are both connected to the gas inlet of the nitrogen exhaust pipeline, and the nitrogen exhaust pipeline is provided with a second sulfur hexafluoride sensor; A pressurized air extraction pipeline is connected between the air inlet side and the air outlet side of the first solenoid valve, and an eighth solenoid valve and a second compressor are sequentially arranged along the air flow direction on the pressurized air extraction pipeline; The method comprises the following steps: (1) Connect the air inlet of the mixed gas extraction pipeline to the air outlet of the GIS equipment; (2) When the pressure sensor detects that the pressure of the SF6 / N2 mixed gas with a sulfur hexafluoride concentration of 30% in the GIS equipment is P>0.35Mpa, the first solenoid valve opens, the eighth solenoid valve closes, and the mixed gas enters the buffer tank through the mixed gas extraction pipeline; when the pressure of the mixed gas is P<0.35Mpa, the eighth solenoid valve opens, the first solenoid valve closes, and the second compressor starts to extract the SF6 / N2 mixed gas in the GIS equipment into the buffer tank; (3) The mixed gas in the buffer tank passes through a large-flow pressure-stabilizing valve to stabilize the pressure to 0.3 MPa, which meets the normal working pressure of the mass flow controller. The flow rate of the mixed gas passing through is controlled by controlling the mass flow controller; (4) The adsorbent in the first adsorption column adsorbs sulfur hexafluoride gas, and the nitrogen in the first adsorption column is discharged into the atmosphere through the nitrogen exhaust pipeline, while the second adsorption column waits; (5) After the adsorbent in the first adsorption column adsorbs sulfur hexafluoride gas for a period of time, the adsorption stops and turns to regeneration. The adsorbed sulfur hexafluoride is stored in a storage tank. At the same time, the second adsorption column adsorbs sulfur hexafluoride gas, and the nitrogen in the second adsorption column is discharged into the atmosphere through the nitrogen exhaust pipeline; (6) After the adsorbent in the second adsorption column adsorbs sulfur hexafluoride gas for a period of time, the adsorption stops and turns to regeneration. The adsorbed sulfur hexafluoride is stored in the storage tank. At the same time, the first adsorption column adsorbs sulfur hexafluoride gas, and the nitrogen in the first adsorption column is discharged into the atmosphere through the nitrogen exhaust pipeline; (7) Repeat steps (5) and (6) until the SF6 / N2 mixed gas in the GIS equipment is completely exhausted.

2. The method according to claim 1, characterized in that: The mass flow controller controls the flow rate of the mixed gas to 50-100 L / min.

3. The method according to claim 1, characterized in that: The process of step (4) is specifically as follows: the second solenoid valve and the sixth solenoid valve are opened, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve and the seventh solenoid valve are closed, the first compressor is turned off, the SF6 / N2 mixed gas adsorbs SF6 gas through the adsorbent in the first adsorption column, and when the second sulfur hexafluoride sensor monitors that the SF6 content in N2 is lower than the emission requirements specified in the relevant standards, the N2 in the first adsorption column is discharged into the air through the first exhaust pipe and the nitrogen exhaust pipeline.

4. The method according to claim 1, characterized in that: The process of step (5) is specifically as follows: the second solenoid valve, the fifth solenoid valve and the sixth solenoid valve are closed, the third solenoid valve and the seventh solenoid valve are opened, the sulfur hexafluoride gas in the mixed gas is adsorbed by the adsorbent in the second adsorption column, and when the second sulfur hexafluoride sensor detects that the SF6 content in the N2 is lower than the emission requirements specified in the relevant standards, the N2 in the second adsorption column is discharged into the air through the second exhaust pipe and the nitrogen exhaust pipeline; at the same time, the first adsorption column is regenerated, the fourth solenoid valve is opened, the first compressor is started, and the SF6 adsorbed in the first adsorption column is extracted into the storage tank. The first sulfur hexafluoride sensor detects the purity of the SF6 extracted into the storage tank, which can make the SF6 gas concentration above 90%.

5. The method according to claim 1, characterized in that: The process of step (6) is specifically as follows: the second solenoid valve and the sixth solenoid valve are opened, the third solenoid valve, the fourth solenoid valve and the seventh solenoid valve are closed, the SF6 / N2 mixed gas adsorbs SF6 gas through the adsorbent in the first adsorption column, and when the second sulfur hexafluoride sensor detects that the SF6 content in N2 is lower than the emission requirements specified in the relevant standards, the N2 in the first adsorption column is discharged into the air through the first exhaust pipe and the nitrogen exhaust pipeline; at the same time, the second adsorption column is regenerated, the fifth solenoid valve is opened, the first compressor is started, and the SF6 adsorbed in the second adsorption column is extracted into the storage tank. The first sulfur hexafluoride sensor detects the purity of the SF6 extracted into the storage tank, which can make the SF6 gas concentration above 90%.

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