A C4F7N mixed gas recovery and charging device

Abstract

The application relates to a C4F7N mixed gas recovery and inflation device and belongs to the technical field of recovery and inflation of insulating gas. The C4F7N mixed gas is first recovered and purified, then is stored in a liquid state through low-temperature refrigeration and pressurization, and when inflation is needed, C4F7N, CO2 or O2 is added to the vaporized C4F7N mixed gas to adjust the mixed gas concentration for inflation use. The C4F7N mixed gas is recovered through low-temperature refrigeration and pressurization and is stored in a liquid state in a container, the filling rate of the container is effectively improved, when inflation is needed, the mixed gas is supplemented to adjust the mixed gas concentration, compared with the existing pure C4F7N gas adjustment, the gas adjustment time is reduced, and the adjustment efficiency is improved.

Description

Technical Field

[0001] This invention relates to a C4F7N mixed gas recovery and filling device, belonging to the field of insulating gas recovery and filling technology. Background Technology

[0002] C4F7N perfluoroisobutyronitrile (PFOBN) has a zero ozone depletion potential, making it an environmentally friendly gaseous insulating medium. To reduce greenhouse gas emissions, the number of C4F7N mixed-insulating gas electrical equipment in my country is gradually increasing. The mixing and charging of C4F7N mixed insulating gas, rapid on-site recovery, and on-site operation and maintenance have become urgent issues to be addressed. Therefore, it is necessary to research efficient mixing and charging technologies and rapid recovery technologies for mixed insulating gases. This is of great significance for meeting the actual needs of C4F7N mixed-insulating gas electrical equipment during operation, building a green power grid, and carrying out the operation and management of mixed-insulating gas electrical equipment.

[0003] Chinese invention patent application CN112516746A, entitled "C4F7N / CO2 Mixed Gas Recovery and Purification Device," discloses a method for recovering and purifying a C4F7N / CO2 mixed gas. The recovered mixed gas is purified by a purification device to remove trace amounts of water, solid particles, and decomposition products generated during discharge. Before recycling, the concentration of the mixed gas needs to be adjusted to meet the requirements for gas recycling. However, this solution does not provide a method for storing the recovered and purified mixed gas. Directly storing the mixed gas would result in an excessively large storage device, which is not conducive to the preservation of the mixed gas. Summary of the Invention

[0004] The purpose of this invention is to provide a C4F7N mixed gas recovery and filling device to solve the problem of inconvenient mixed gas storage in the current recovery and filling process.

[0005] To solve the above-mentioned technical problems, this invention provides a C4F7N mixed gas recovery and charging device, comprising a recovery and purification unit, a refrigerated liquid storage unit, a vaporization unit, and a mixing and charging unit. The recovery and purification unit is used to recover, purify, and compress the C4F7N mixed gas; the refrigerated liquid storage unit is used to cool and store the compressed C4F7N mixed gas after recovery and purification in a liquid state; the vaporization unit is used to vaporize and heat the liquid-stored C4F7N mixed gas; and the mixing and charging unit is used to adjust the vaporized mixed gas so that the concentration of the C4F7N mixed gas reaches a set concentration standard.

[0006] This invention first recovers and purifies a C4F7N mixed gas, then stores it in a liquid state through cryogenic refrigeration and pressurization. When inflation is needed, a vaporization unit vaporizes the liquid C4F7N mixed gas, and a mixing and inflation unit adds C4F7N, CO2, or O2 to the vaporized C4F7N mixed gas to adjust the concentration, allowing the C4F7N mixed gas bag to be used with a set concentration standard. This invention uses cryogenic refrigeration and pressurization to recover the C4F7N mixed gas and store it in a liquid state in a container, effectively improving the container's filling rate. When inflation is needed, the concentration of the C4F7N mixed gas is adjusted by the mixing and inflation unit. Compared with existing methods that use pure C4F7N gas for adjustment, this reduces the gas adjustment time and increases adjustment efficiency.

[0007] Furthermore, the refrigerated liquid storage unit includes a storage tank. The inlet of the storage tank is connected to the outlet of the recovery and purification unit via a pipeline. A heat exchanger module is installed on the pipeline between the inlet of the storage tank and the outlet of the recovery and purification unit. The heat exchanger module is used to refrigerate and heat exchange the gas in the recovery and purification pipeline.

[0008] Furthermore, the heat exchanger module includes a plate heat exchanger and a refrigeration unit. The plate heat exchanger includes a first channel and a second channel. The first channel is connected in series in the pipeline between the inlet of the liquid storage tank and the outlet of the recovery and purification unit. The second channel is connected to the refrigeration unit and is used to cool the medium in the second channel.

[0009] Using a plate heat exchanger to cool the recovered mixed gas results in a better cooling effect.

[0010] Furthermore, the mixing and filling unit includes a mixing tank and a gas replenishment branch. The first inlet of the mixing tank is connected to the outlet of the vaporization unit through a pipeline and is used to store the recovered mixed gas. One end of each gas replenishment branch is connected to a single gas source of C4F7N, CO2, and O2, respectively, and the other end is used to connect to the second inlet of the mixing tank. A detector is installed at the first inlet of the mixing tank to detect the concentration of C4F7N mixed gas. The detector is connected to the controller. The controller controls the valve on the corresponding gas replenishment branch to replenish gas according to the detection data of the detector, so that the concentration of C4F7N mixed gas in the mixing tank reaches the set concentration standard.

[0011] A gas replenishment branch is connected to the inlet of the liquid storage tank. Gas is replenished by controlling the valve to adjust the concentration of the mixed gas, making the adjustment of the mixed gas concentration more convenient.

[0012] Furthermore, the mixing and charging unit also includes a mixer, which is installed on the pipeline between the gas supply branch and the second inlet of the mixing tank. The inlet is connected to the gas supply branch, and the mixer outlet is connected to the second inlet of the mixing tank. It is used to receive the single gas supplied by each gas supply branch and mix it according to the set concentration standard, and then transmit it to the mixing tank or directly to the gas chamber.

[0013] The mixed inflation unit can adjust the concentration of the recovered and purified C4F7N mixed gas to meet the inflation requirements, or it can use the new mixed gas generated by each branch to be directly mixed and used for inflation, thus improving inflation efficiency.

[0014] Furthermore, each gas replenishment branch is equipped with a pressure sensor, which is connected to the controller. When the pressure in the gas cylinder is insufficient, the sensor transmits a signal to the control module to stop the filling process and issue a gas cylinder pressure insufficient signal.

[0015] Pressure sensors can promptly reflect the gas content in gas cylinders, allowing for timely replenishment or replacement when gas levels are insufficient.

[0016] Furthermore, it also includes a vacuum pumping unit, which is used to evacuate the gas chamber before it is filled with gas.

[0017] Vacuuming the air chamber before inflation ensures a vacuum environment, facilitating inflation.

[0018] Furthermore, a mixed gas buffer tank is installed in the gas chamber inlet pipeline to buffer the C4F7N mixed gas.

[0019] Furthermore, the recovery and purification unit includes a pipeline for connecting to the mixed gas recovery port, and a dryer, filter and compressor are installed on the pipeline to dry, filter and compress the recovered C4F7N mixed gas.

[0020] Furthermore, a liquid level sensor is installed in the storage tank, which is connected to the controller to transmit a signal to the controller when the storage tank is full, thereby stopping the recycling process.

[0021] The liquid level sensor can promptly alert the tank to be full and stop recycling. Attached Figure Description

[0022] Figure 1 This is a flowchart of the C4F7N mixed gas recovery and charging device of the present invention; Wherein: 1 is the C4F7N mixed gas recovery port; 2 is the first pressure sensor, 6 is the second pressure sensor, 9 is the third pressure sensor, 28 is the fourth pressure sensor, 32 is the fifth pressure sensor, 40 is the sixth pressure sensor, 47 is the seventh pressure sensor, 50 is the eighth pressure sensor, 57 is the ninth pressure sensor, 74 is the tenth pressure sensor, 79 is the eleventh pressure sensor, and 71 is the twelfth pressure sensor; 3 is the first dust filter, 12 is the second dust filter, 21 is the third dust filter, 46 is the fourth dust filter, 51 is the fifth dust filter, and 58 is the sixth dust filter. 75 is the seventh dust filter; 4 is the first pressure reducer, 23 is the second pressure reducer, 44 is the third pressure reducer, 54 is the fourth pressure reducer, 61 is the fifth pressure reducer; 5 is the first axial flow solenoid valve, 14 is the second axial flow solenoid valve, 16 is the third axial flow solenoid valve, 18 is the fourth axial flow solenoid valve, 19 is the fifth axial flow solenoid valve, 26 is the sixth axial flow solenoid valve, 37 is the seventh axial flow solenoid valve, 41 is the eighth axial flow solenoid valve, 45 is the ninth axial flow solenoid valve, 52 is the tenth axial flow solenoid valve, 53 is the eleventh axial flow solenoid valve, 59 is the twelfth axial flow solenoid valve, 60 is the thirteenth axial flow solenoid valve, 63 is the fourteenth axial flow solenoid valve. Valves: 64 is the fifteenth axial flow solenoid valve, 65 is the sixteenth axial flow solenoid valve, 69 is the seventeenth axial flow solenoid valve, 70 is the eighteenth axial flow solenoid valve, 77 is the nineteenth axial flow solenoid valve, 78 is the twentieth axial flow solenoid valve; 7 is a buffer tank; 8 is a C4F7N mixed gas recovery compressor; 10 is the first electric valve, 25 is the second electric valve, 27 is the third electric valve, 30 is the fourth electric valve; 11 is a dryer; 13 is a plate heat exchanger; 15 is a refrigeration unit; 17 is a booster pump; 20 is a mixed gas detection port; 22 is a heater; 24 is a one-way valve; 29 is the first safety valve, 33 is the second safety valve, 76 is the third... Safety valve; 31 is the liquid injection port; 34 is the liquid storage tank; 35 is the liquid level gauge; 36 is the weighing sensor; 38 is the mixed gas charging port; 39 is the mixing tank; 42 is the mixer; 43 is the first mass flow controller, 55 is the second mass flow controller, 62 is the third mass flow controller; 48 is the C4F7N gas inlet; 49 is the CO2 gas inlet; 56 is the O2 gas inlet; 66 is the first back pressure valve, 81 is the second back pressure valve; 67 is the vacuum pump; 68 is the electromagnetic vacuum valve; 72 is the vacuum extraction port; 73 is the mixed gas charging port; 80 is the C4F7N mixed gas pressurizing compressor; 82 is the mixed gas buffer tank. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0024] Example of a C4F7N mixed gas recovery and charging device This invention includes a recovery and purification unit, a refrigerated liquid storage unit, a vaporization unit, a mixing and charging unit, and a vacuum unit. The recovery and purification unit is used to recover and purify the C4F7N mixed gas. The refrigerated liquid storage unit is used to cool and store the recovered and purified C4F7N mixed gas in liquid form. The vaporization unit is used to vaporize and heat the stored C4F7N mixed gas. The mixing and charging unit is used to mix and charge C4F7N, CO2, and O2 and to adjust the concentration of the C4F7N mixed gas. During charging, the liquid C4F7N mixed gas vaporizes and enters the mixing tank. The gas ratio in the mixing tank is measured, and the concentration of the mixed gas is adjusted by adding C4F7N, CO2, or O2. The adjusted mixed gas is then pumped into the charging switch. Specific examples will be used to illustrate this further.

[0025] The structure of the device is as follows Figure 1 As shown, the recovery and purification unit includes a pipeline connected to the C4F7N mixed gas recovery port 1. The pipeline is equipped with a first pressure sensor 2, a second pressure sensor 6, a third pressure sensor 9, a first dust filter 3, a second dust filter 12, a first pressure reducer 4, a first axial flow solenoid valve 5, a third axial flow solenoid valve 16, a fourth axial flow solenoid valve 18, a first electric valve 10, a dryer 11, a buffer tank 7, a C4F7N mixed gas recovery compressor 8, and a booster pump 17. The outlet of the second dust filter 12 is connected to a refrigerated liquid storage unit. The first pressure sensor 2 is used to detect the C4F7N mixed gas recovery port 1 pipeline; the second pressure sensor 6 is used to detect the buffer tank 7; the third pressure sensor 9 is used to detect the gas compressed by the C4F7N mixed gas recovery compressor 8; the first dust filter 3 and the second dust filter 12 are used to filter the mixed gas in the pipeline; the dryer 11 adsorbs water and decomposition products in the C4F7N mixed gas in the switch chamber; and the C4F7N mixed gas recovery compressor 8 is used to pressurize the recovered mixed gas.

[0026] The refrigerated liquid storage unit includes a storage tank 34. A refrigeration unit 15, a plate heat exchanger 13, a one-way valve 24, a second axial flow solenoid valve 14, a sixth axial flow solenoid valve 26, and a third electric valve 27 are installed on the pipeline between the inlet of the storage tank 34 and the outlet of the recovery and purification unit. The plate heat exchanger 13 includes a first channel and a second channel. The first channel is connected in series in the pipeline between the inlet of the storage tank and the outlet of the recovery and purification unit, and the second channel is connected to the refrigeration unit 15 for cooling the medium in the second channel. The storage tank 34 is equipped with a first safety valve 29, a fourth pressure sensor 28, a level gauge 35, and a weighing sensor 36. The storage tank 34 is used to store liquid C4F7N mixed gas. The fourth pressure sensor 28 is used to detect the pressure in the storage tank 34, and the level gauge 35 is used to detect the liquid level of the liquid C4F7N mixed gas in the storage tank 34.

[0027] The refrigerated liquid storage unit also includes a liquid injection port 31, which is used to refrigerate and liquefy the mixed gas in the storage tank 34 and then press it into the steel cylinder through the liquid injection port, or to refrigerate and liquefy the directly recovered mixed gas and then press it into the steel cylinder through the liquid injection port.

[0028] The vaporization unit is located between the refrigerated liquid storage unit and the mixing and charging unit. The vaporization unit includes a heater 22. A fourth electric valve 30 and a second pressure reducer 23 are installed on the pipeline connecting the heater 22 to the refrigerated liquid storage unit. A third dust filter 21, a mixed gas detection port 20, and a seventh axial flow solenoid valve 37 are installed on the pipeline connecting the heater 22 to the mixing and charging unit. The heater 22 is used to vaporize and heat the stored C4F7N mixed gas. The third dust filter 21 is used to filter the vaporized C4F7N mixed gas. The mixed gas detection port 20 is used to detect the concentration of C4F7N mixed gas in the pipeline.

[0029] The mixing and gasification unit includes a mixing tank 39 and gas replenishment branches. The first inlet of the mixing tank is connected to the outlet of the vaporization unit via a pipeline and is used to store the recovered mixed gas. One end of each gas replenishment branch is connected to a single gas source of C4F7N, CO2, or O2, respectively, and the other end is connected to the second inlet of the mixing tank 39. The C4F7N gas replenishment branch pipeline is equipped with a fourth dust filter 46, a seventh pressure sensor 47, a third pressure reducer 44, a ninth axial flow solenoid valve 45, and a first mass flow controller 43. The CO2 gas replenishment branch pipeline is equipped with a fifth dust filter 51, an eighth pressure sensor 50, a fourth pressure reducer 54, a second mass flow controller 55, and an eleventh axial flow solenoid valve 53. The O2 gas replenishment branch pipeline is equipped with a ninth pressure sensor 57, a sixth dust filter 58, a thirteenth axial flow solenoid valve 60, and a fifth pressure reducer. 61. The third mass flow controller 62, a detector is installed at the first inlet of the mixing tank 39 to detect the concentration of C4F7N mixed gas. The detector is connected to the controller. The controller controls the valve on the corresponding gas supply branch to supply gas according to the detection data of the detector, so that the concentration of C4F7N mixed gas in the mixing tank 39 reaches the set concentration standard. The mixing tank 39 is equipped with a sixth pressure sensor 40. The outlet pipeline of the mixing tank 39 is connected to the gas chamber. The pipeline is equipped with a fifteenth axial flow solenoid valve 64, an eleventh pressure sensor 79, a twentieth axial flow solenoid valve 78, a mixed gas buffer tank 82, a third safety valve 76, a seventh dust filter 75, and a tenth pressure sensor 74. The C4F7N mixed gas recovery port 1 can be directly connected to the inlet of the mixing tank 39 through the first pressure sensor 2 and the fifth axial flow solenoid valve 19.

[0030] In another embodiment, the mixer is located between the gas supply branch and the mixing tank. An eighth axial flow solenoid valve 41 is provided between the mixer 42 and the mixing tank 39. The mixer 42 is connected to the eleventh pressure sensor 79 in the output pipeline of the mixing tank through the fourteenth axial flow solenoid valve 63, the first back pressure valve 66, the C4F7N mixed gas pressurization compressor 80, and can directly generate new C4F7N mixed gas through the gas supply branch to supply the gas chamber.

[0031] The mixing and charging unit also includes a mixed gas charging inlet 38, which is connected to the C4F7N mixed gas pressurizing compressor 80 in the mixing tank outlet pipeline through the sixteenth axial flow solenoid valve 65 and the second back pressure valve 81, and can directly charge the gas chamber with a standard concentration of C4F7N mixed gas.

[0032] The vacuum unit includes a vacuum branch, which is equipped with a vacuum pump 67, a vacuum port 72, an electromagnetic vacuum valve 68, a twelfth pressure sensor 71, and a seventeenth axial flow solenoid valve 69. The vacuum branch is connected to each gas supply branch through the tenth axial flow solenoid valve 52, the twelfth axial flow solenoid valve 59, and the eighteenth axial flow solenoid valve 70, and is connected to the output pipeline of the mixing tank 39 through the nineteenth axial flow solenoid valve 77. The vacuum unit is used to perform vacuum treatment on the gas chamber before it is filled with gas, and is also used to perform vacuum treatment on the entire system of the device after initial use or maintenance to reduce contamination of the pipeline by other impurities.

[0033] The recovery and purification unit and the refrigerated liquid storage unit enable the liquefaction and storage of the recovered gas: The mixed gas chamber is connected via a hose to the C4F7N mixed gas recovery port 1 of the C4F7N mixed gas recovery and charging device. The first electric valve 10, the third electric valve 27, the first axial flow solenoid valve 5, the second axial flow solenoid valve 14, the sixth axial flow solenoid valve 26, the refrigeration unit 15, and the C4F7N mixed gas recovery compressor 8 are then activated to begin gas recovery. The dryer 11 adsorbs water and decomposition products from the C4F7N mixed gas in the switching gas chamber. The compressor pressurizes the gas, and simultaneously, the heat exchanger and refrigeration unit 15 cool the pressurized high-temperature gas, thus storing the C4F7N mixed gas in a liquid state in a container or cylinder. When the fourth pressure sensor 28 reaches the set pressure of the gas chamber, a signal is transmitted to the control module, stopping the recovery and issuing a recovery completion signal. When the liquid level or pressure in the storage tank reaches the set value, the compressor stops returning gas and issues a storage tank full signal.

[0034] When inflation is required, connect the gas chamber to the mixing inflation port 73 via a hose. Connect the C4F7N gas cylinder, CO2 gas cylinder, and O2 gas cylinder to the C4F7N gas inlet 48, CO2 gas inlet 49, and O2 gas inlet 56 via hoses. Sequentially open the ninth axial flow solenoid valve 45, the eleventh axial flow solenoid valve 53, and the thirteenth axial flow solenoid valve 60, and start the first mass flow controller 43, the second mass flow controller 55, and the third mass flow controller 62. Open the eighth axial flow solenoid valve 41, the sixteenth axial flow solenoid valve 65, and the twentieth axial flow solenoid valve 78. Start the C4F7N mixed gas pressurization compressor 80 to begin mixing and inflation. When the tenth pressure sensor 74 at the mixing inflation port reaches the set pressure of the gas chamber, the pressure transmitter sends a signal to the control module, stopping inflation and issuing an inflation complete signal. When the C4F7N gas cylinder pressure is insufficient, the seventh pressure sensor 47 sends a signal to the control module, stopping inflation and issuing a C4F7N gas cylinder low pressure signal. When the CO2 cylinder pressure is insufficient, the eighth pressure sensor 50 sends a signal to the control module, stopping the filling process and issuing a CO2 cylinder pressure insufficient signal. When the O2 cylinder pressure is insufficient, the ninth pressure sensor 57 sends a signal to the control module, stopping the filling process and issuing an O2 cylinder pressure insufficient signal.

[0035] Connect the gas chamber to the mixing port 73 via a hose. Open the fourth electric valve 30, heater 22, and seventh axial flow solenoid valve 37 sequentially to fill the mixing tank 39 with the mixed gas from the storage tank 34 until the set pressure is reached. Then close the fourth electric valve 30, heater 22, and seventh axial flow solenoid valve 37. Measure the gas-mixing ratio in the mixing tank 39 using an external detector and calculate the make-up gas concentration. According to the make-up gas concentration, open the ninth axial flow solenoid valve 45, eleventh axial flow solenoid valve 53, and thirteenth axial flow solenoid valve 60 sequentially and start the first mass flow controller 43 and the second mass flow controller 44. Controller 55 and the third mass flow controller 62 open the fourteenth axial flow solenoid valve 63 and the fifteenth axial flow solenoid valve 64, starting the C4F7N mixed gas pressurizing compressor 80 to adjust the gas-mix ratio. After the replenishment pressure (sixth pressure sensor 40) reaches the set pressure, the ninth axial flow solenoid valve 45, the eleventh axial flow solenoid valve 53, the thirteenth axial flow solenoid valve 60, the first mass flow controller 43, the second mass flow controller 55, the third mass flow controller 62, the fourteenth axial flow solenoid valve 63, and the fifteenth axial flow solenoid valve 64 stop. The sixteenth axial flow solenoid valve 65 and the twentieth axial flow solenoid valve 78 open, and the C4F7N mixed gas pressurizing compressor pressurizes the adjusted mixed gas in the mixing tank into the switch. The mixed gas inlet 38 can directly replenish the gas chamber with standard concentration C4F7N mixed gas.

[0036] In this embodiment, the liquid storage tank is an internal spiral coil stainless steel tank, the mass flow controller is a laminar flow mass flow controller, all interfaces are self-sealing valve joints, and the heat exchanger is a plate heat exchanger.

[0037] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A C4F7N mixed gas recovery and charging device, characterized in that, The system includes a recovery and purification unit, a refrigerated liquid storage unit, a vaporization unit, and a mixing and charging unit. The recovery and purification unit, connected to the mixed gas recovery port via pipeline, is used to recover, purify, and compress the C4F7N mixed gas. The refrigerated liquid storage unit cools the compressed C4F7N mixed gas after recovery and purification, storing it in a liquid state. It includes a storage tank, which is a stainless steel tank with an internal spiral coil. The inlet of the storage tank is connected to the outlet of the recovery and purification unit via pipeline. A heat exchanger module is installed on the pipeline between the inlet of the storage tank and the outlet of the recovery and purification unit, used for cooling and heat exchange of the gas in the pipeline. The vaporization unit is used to vaporize and heat the liquid-stored C4F7N mixed gas. The mixing and charging unit is used to adjust the vaporized mixed gas to achieve a set concentration of C4F7N. The mixing and charging unit includes a mixing tank, a mixer, and gas supply branches. One end of each gas supply branch is connected to a single gas source of C4F7N, CO2, or O2, respectively. The other end of each gas supply branch is connected to the inlet of the mixer, and the outlet of the mixer is connected to the second inlet of the mixing tank. The mixer is used to receive the single gas supplied by each gas supply branch and mix them according to the set concentration standard, and then transfer them to the mixing tank or directly to the gas chamber. The first inlet of the mixing tank is connected to the outlet of the vaporization unit. This first inlet is also directly connected to the mixed gas recovery port through a pipeline and a solenoid valve. The first outlet of the mixing tank is connected to the gas chamber through a pressurization compressor, and the second outlet of the mixing tank is not connected to the gas chamber through a pressurization compressor. The mixing and charging unit also includes a mixed gas charging inlet for directly charging the gas chamber with a standard concentration of C4F7N mixed gas.

2. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, A sixth pressure sensor is installed on the mixing tank.

3. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, The heat exchanger module includes a plate heat exchanger and a refrigeration unit. The plate heat exchanger includes a first channel and a second channel. The first channel is connected in series in the pipeline between the inlet of the liquid storage tank and the outlet of the recovery and purification unit. The second channel is connected to the refrigeration unit and is used to cool the medium in the second channel.

4. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, A detector is installed at the first inlet of the mixing tank to detect the concentration of C4F7N mixed gas. The detector is connected to the controller, and the controller controls the valve on the corresponding gas supply branch to supply gas according to the detection data of the detector, so that the concentration of C4F7N mixed gas in the mixing tank reaches the set concentration standard.

5. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, The pipeline connected to the mixed gas recovery port in the recovery and purification unit is equipped with a dryer, a filter, and a compressor to dry, filter, and compress the recovered C4F7N mixed gas.

6. The C4F7N mixed gas recovery and charging device according to claim 4, characterized in that, Each gas replenishment branch is equipped with a pressure sensor, which is connected to the controller. When the pressure in the gas cylinder is insufficient, the sensor sends a signal to the control module to stop the filling process and issue a gas cylinder pressure insufficient signal.

7. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, It also includes a vacuum pumping unit, which is used to evacuate the gas chamber before it is filled with gas.

8. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, A mixed gas buffer tank is installed in the gas chamber inlet pipeline to buffer the C4F7N mixed gas.

9. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, The vacuum unit includes a vacuum branch, which is connected to each gas supply branch via solenoid valves.

10. The C4F7N mixed gas recovery and charging device according to claim 1, characterized in that, The storage tank is equipped with a liquid level sensor that communicates with the controller. The sensor sends a signal to the controller when the storage tank is full, stopping the recycling process.

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