Portable sulfur hexafluoride and nitrogen mixing and supplementing device and method

Abstract

The invention relates to the technical field of high-voltage electrical equipment maintenance, and provides a portable sulfur hexafluoride and nitrogen mixing and supplementing device and method.The device comprises an inflation gas circuit, a gas mixing device and a gas pressurization supplementing branch which are arranged in a case; the inflation gas circuit comprises a sulfur hexafluoride inflation gas circuit and a nitrogen inflation gas circuit which are arranged in parallel; the gas mixing device comprises a mixing cavity, a porous jet flow plate, a sawtooth baffle set and a porous wave baffle are sequentially arranged in the mixing cavity from left to right, and the gas pressurization supplementing branch comprises a booster pump branch and a conventional branch which are arranged in parallel. The two gas paths are jointly communicated with a differential pressure gauge used for coupling the two gas pressure equalizing buffer devices. According to the device and the method, the proportion of the mixed gas can be accurately prepared, the gas supplementing requirement of the gas chamber of the switch equipment is met, and operation and maintenance personnel can conveniently and efficiently carry out gas supplementing operation of the gas chamber of the switch equipment in time.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage electrical equipment maintenance technology, specifically relating to a portable sulfur hexafluoride and nitrogen mixing and replenishment device and method. Background Technology

[0002] Sulfur hexafluoride (SF6) gas is widely used in gas-insulated switchgear (GIS) due to its excellent insulation and arc-quenching properties. However, pure SF6 gas can liquefy at low temperatures, affecting equipment performance and increasing costs. Therefore, in practical applications, especially in areas with low ambient temperatures, a mixture of SF6 and nitrogen (N2) (typically SF6 / N2 = 30% / 70%) is often used as the insulating medium to balance performance, cost, and liquefaction prevention requirements. During long-term operation, the internal gas pressure of switchgear may decrease due to factors such as seal aging, requiring timely gas replenishment to maintain its insulation strength.

[0003] Currently, there is no dedicated gas mixing and replenishment device. Conventional gas filling devices are designed for high-flow-rate filling, and the mixing ratio deviates significantly in the initial stage of gas distribution. According to measurements and statistics, the gas filling volume of switchgear gas chambers ranges from 20 liters to 1150 liters (converted to atmospheric pressure gas). At low flow rates, the existing gas filling devices cannot achieve precise gas filling. Inaccurate control of the mixing ratio during gas filling will lead to an imbalance in the gas mixture ratio within the gas chamber, creating serious safety hazards.

[0004] Chinese patent CN107321203B discloses a gas mixing device for nitrogen and sulfur hexafluoride. This device initially mixes the two gases in a gas pipe, and then performs a secondary mixing between a cylindrical container with guide vanes and the outer shell to achieve thorough mixing of nitrogen and sulfur hexafluoride. Although the patent includes solenoid valves on each gas pipe to control the gas intake, it lacks specific gas flow and pressure detection mechanisms, thus failing to accurately control the ratio of the two gases, resulting in an unsatisfactory mixing effect. Furthermore, to ensure smooth gas filling, the gas source pressure must always be higher than the gas chamber of the switching equipment. This means that when the device is shut down, some sulfur hexafluoride gas will be released. Sulfur hexafluoride is a strong greenhouse gas, with a global warming coefficient approximately 23,900 times that of carbon dioxide. Leakage would cause long-term and continuous environmental pollution. The patent lacks an effective pressure regulation mechanism to prevent the release of sulfur hexafluoride gas. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a portable sulfur hexafluoride and nitrogen mixing and replenishment device and method. This device and method can accurately prepare the mixed gas ratio to meet the replenishment requirements of switchgear gas chambers, which is more conducive to maintenance personnel performing timely and efficient replenishment operations of switchgear gas chambers.

[0006] To achieve the above objectives, the technical solution provided by this invention is as follows: A portable sulfur hexafluoride and nitrogen mixing and replenishment device includes a chassis, wherein the chassis is provided with a gas filling path, a gas mixing device and a gas pressurization and replenishment branch connected sequentially along the gas flow direction; The gas filling circuit includes a sulfur hexafluoride gas filling circuit and a nitrogen gas filling circuit arranged in parallel. The gas mixing device includes a mixing chamber, a sulfur hexafluoride gas inlet is provided at the left end of the mixing chamber, and a porous jet plate, a sawtooth baffle group and a porous corrugated baffle are arranged sequentially from left to right inside the mixing chamber. A nitrogen gas inlet is provided on the side wall of the mixing chamber and in the area between the porous jet plate and the sawtooth baffle group. A mixed gas outlet is provided at the right end of the mixing chamber. The gas pressurization supplementary branch includes a booster pump branch and a conventional branch connected in parallel.

[0007] Preferably, the upper end of the side wall of the mixing chamber is provided with a side cut, and a buffer zone is provided outside the side cut. The mixing chamber and the buffer zone are connected through the side cut, and the nitrogen gas inlet is located on the outer side of the buffer zone.

[0008] Preferably, the plane of each sawtooth baffle in the sawtooth baffle group makes an angle of 60° with the airflow direction, forcing the airflow to deflect laterally (both horizontally and vertically) at the same time, forming three-dimensional turbulence, and the sawtooth directions of two adjacent layers of sawtooth baffles are opposite.

[0009] Preferably, the mixing cavity has a flat structure with a length-to-width ratio of 15:1 and a thickness-to-width ratio of 1:3 to 1:5.

[0010] Preferably, each gas filling circuit includes a gas cylinder, a pressure reducing valve, a normally closed solenoid valve, a check valve, a pressure transmitter, a gas equalization buffer device, and a flow controller connected in sequence; the gas equalization buffer devices in the two gas circuits are connected together by a differential pressure gauge for coupling the two gas equalization buffer devices.

[0011] Preferably, the pipeline section between the one-way valve and the pressure transmitter in each gas charging path is connected to a temperature equalizer; the temperature equalizer is equipped with a gas heat exchange pipeline that first exchanges heat in reverse and then equalizes the temperature in the same direction.

[0012] Preferably, the chassis is also equipped with a full-pipeline vacuum system, which includes a vacuum pump connected to multiple parallel vacuum branches.

[0013] Preferably, the vacuuming branch includes: a pipeline between the one-way valve and the temperature equalizer in each inflation pipeline, a pipeline between the gas mixing device and the gas pressurization and replenishment branch, and a pipeline between the gas pressurization and replenishment branch and the inflation interface.

[0014] Preferably, each of the vacuuming branches is equipped with a control valve, and all control valves form a solenoid valve group, which controls all vacuuming branches to open or close synchronously.

[0015] This invention also discloses a method for filling the gas chamber of switchgear using the aforementioned portable sulfur hexafluoride and nitrogen mixing and replenishing device, as detailed below: Step 1: Connect the gas cylinder, pressure reducing valve, filling interface and the gas chamber of the switch to be filled, close the gas cylinder valve, and turn on the vacuum pump to evacuate the entire pipeline. Step 2: Open the gas cylinder valve to inject gas into the corresponding gas equalization buffer device in each gas line. Adjust the pressure of the two gas lines to the preset value through the pressure reducing valve. Monitor the pressure value in real time through the pressure transmitter and differential pressure gauge. Step 3: Turn on the mass flow controller and inject the proportioned gas, which has been adjusted by the mass flow controller, into the gas mixing device for mixing. Step 4: After replenishing the gas through the gas pressurization and replenishment branch, the mixed gas is filled into the gas chamber of the switchgear; Step 5: After the gas pressure in the gas chamber of the switching equipment reaches the preset value, first close the solenoid valves in the two parallel gas circuits, monitor the pressure of the sulfur hexafluoride buffer tank in the gas equalization buffer device through the pressure transmitter, and after the pressure of the sulfur hexafluoride buffer tank is drawn down to the normal pressure by the booster pump, turn off the booster pump, stop the device, and complete the gas replenishment operation.

[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) By setting up a gas equalization buffer device, it can be ensured that the two mass flow controllers adjust the gas source pressure to be the same. Combined with the same PID adjustment coefficient of the same mass flow controllers from the same manufacturer and of the same model, the gas ratio output deviation of the two mass flow controllers during the adjustment stage can be effectively reduced.

[0017] (2) By setting up a flat gas mixing device, the mixed airflow is transformed into a vortex airflow, which can fully mix the gas. It saves more space than the common cylindrical baffle structure and is conducive to the miniaturization of the device.

[0018] (3) In this invention, the mixed gas is controlled by the device itself. When the gas source pressure is high, it is directly injected into the gas chamber of the switch equipment, or when the gas source pressure is low, it is injected into the gas chamber of the switch equipment after being pressurized by a booster pump. This can reduce the running time of the oil-free compressor and extend the service life of the equipment.

[0019] (4) A bypass solenoid valve is installed in parallel with the pipeline that acts with the check valve, which can effectively prevent the pipeline from being evacuated incompletely due to the inherent opening pressure of the check valve when evacuating the pipeline.

[0020] (5) Solenoid valves are installed at the gas inlet and outlet of the device. By controlling the solenoid valves to close before shutdown, the compressor draws sulfur hexafluoride in the buffer tank to atmospheric pressure, further reducing the discharge of sulfur hexafluoride after shutdown. The normally closed solenoid valves can ensure that the clean gas in the device does not come into contact with the outside air after the device is shut down, and ensure that the pipelines and other devices in the equipment are protected from external gas corrosion. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall connection structure of the present invention; Figure 2 This is a schematic diagram of the planar structure of a gas mixing device; Figure 3 This is a three-dimensional structural diagram of a gas mixing device; In the diagram: 1-Sulfur hexafluoride cylinder, 2-First pressure reducing valve, 3-First solenoid valve, 4-Second solenoid valve, 5-First check valve, 6-Vacuum gauge, 7-Sulfur hexafluoride gas pipeline, 8-Nitrogen cylinder, 9-Second pressure reducing valve, 10-Third solenoid valve, 11-Fourth solenoid valve, 12-Second check valve, 13-Nitrogen gas pipeline, 14-Temperature equalizer, 15-First pressure transmitter, 16-Second pressure transmitter, 17-Gas equalization buffer device, 18-Differential pressure gauge, 19-First mass flow controller, 20-Second mass flow controller, 21-Gas mixing device, 2101-Mixing chamber, 2102-Sulfur hexafluoride cylinder 2103-Sulfur fluoride gas inlet, 2104-Nitrogen gas inlet, 2105-Cavity side cut, 2106-Porous jet plate, 2107-Serrated baffle assembly, 2108-Porous corrugated baffle, 2109-Conical guide cone, 2109-Mixed gas outlet, 22-Third pressure transmitter, 23-Booster pump, 24-Fifth solenoid valve, 25-Mixed gas pipeline, 26-Sixth solenoid valve, 27-Fourth pressure transmitter, 28-Seventh solenoid valve, 29-Third check valve, 30-Eighth solenoid valve, 31-Inlet, 32-Solenoid valve assembly, 33-Vacuum pump, 34-Fourth check valve, 35-Vacuum pump outlet. Detailed Implementation

[0023] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0024] The portable sulfur hexafluoride and nitrogen mixing and replenishment device provided in this embodiment includes a sulfur hexafluoride and nitrogen replenishment gas path connected in parallel, a temperature equalizer 14, a gas pressure equalization buffer device 17, a gas mixing device 21, a gas pressurization and replenishment branch, and a pipeline vacuum system. All components are sealed together by pressure-resistant stainless steel pipes, and the electromechanical unit is controlled by a PLC system. The entire device is integrated into a portable chassis, meeting the needs of mobile gas replenishment operations in the field. The sulfur hexafluoride (SF6) filling gas path consists of an SF6 cylinder 1, a first pressure reducing valve 2, a first solenoid valve 3, a first check valve 5, and a vacuum gauge 6 connected in sequence along the gas flow direction. The first pressure reducing valve 2 is a precision pressure regulating valve that can adjust the cylinder output pressure to 0.1–1 MPa. The first check valve 5 is made of stainless steel and can effectively prevent the mixed gas from flowing back and contaminating the cylinder. The first check valve 5 is connected in parallel with a second solenoid valve 4. When evacuating the pipeline, the second solenoid valve 4 is opened to form a passage, avoiding incomplete vacuum evacuation caused by the opening pressure of the first check valve 5.

[0025] The structure of the nitrogen filling gas circuit is symmetrical and connected in parallel with the sulfur hexafluoride filling gas circuit. Along the gas flow direction, the nitrogen cylinder 8, the second pressure reducing valve 9, the third solenoid valve 10, the second one-way valve 12, and the fourth solenoid valve 11 connected in parallel with the second one-way valve 12 are connected in series. The parameters of each component are consistent with the corresponding components of the sulfur hexafluoride filling gas circuit to ensure that the initial pressure regulation capabilities of the two gas circuits are matched.

[0026] Sulfur hexafluoride gas line 7 and nitrogen gas line 13 are both connected downstream of their respective check valves to temperature equalizer 14, and from the outlet of temperature equalizer 14 are respectively connected to gas pressure equalization buffer device and flow quality controller, and finally converge at gas mixing device 21.

[0027] The temperature equalizer 14 is a miniature plate heat exchanger that uses a gas heat exchange pipeline that first exchanges heat in the reverse direction and then equalizes the temperature in the same direction, so as to achieve the maximum temperature equalization effect in a small volume.

[0028] The gas mixing device 21 includes a mixing chamber 2101, a sulfur hexafluoride gas inlet 2102 located at the left end of the mixing chamber 2101, a nitrogen gas inlet 2103 located on the side of the mixing chamber 2101, and a mixed gas outlet 2109 located at the right end of the mixing chamber 2101. The mixing chamber 2101 has a flat structure with a length-to-width ratio of 15:1 and a thickness-to-width ratio of 1:3 to 1:5 to balance the mixing space and pressure drop. A porous jet plate 2105, a serrated baffle group 2106, and a porous wave baffle 2107 are arranged sequentially from left to right inside the mixing chamber 2101. The sulfur hexafluoride gas inlet 2102 and the porous jet plate 2105 form a sulfur hexafluoride gas buffer and equalization cavity, ensuring a consistent flow velocity of the sulfur hexafluoride gas through the porous jet plate 2105. The porous jet plate 2105 is configured according to the designed flow rate of the sulfur hexafluoride gas to achieve a reasonable jet velocity. The cavity side cutout 2104 is a tangential slit inlet located on the side wall of the mixing cavity. The length and width of the slit are configured according to the designed flow rate of the nitrogen gas to form a swirling flow. The cavity side cutout 2104 is located 20-30 mm behind the porous jet plate 2105 and 30-50 mm in front of the first row of sawtooth baffles in the sawtooth baffle group 2106, ensuring that after the sulfur hexafluoride initially diffuses through the porous jet plate 2105, it interacts and mixes with the stable swirling gas formed in the cavity side cutout 2104, and then forms a vortex-enhanced mixing through the sawtooth baffle group 2106.

[0029] The sawtooth baffle assembly 2106 consists of multiple rows, columns, and layers of sawtooth baffles arranged in a three-dimensional manner along the airflow direction within the mixing cavity 2101. The sawtooth baffles are sawtooth-shaped, and the plane containing the sawtooth baffles forms an angle of 60° with the airflow direction, forcing the airflow to deflect laterally (both horizontally and vertically) simultaneously, forming three-dimensional turbulence. The sawtooth directions of adjacent layers of sawtooth baffles are opposite. The first row of sawtooth baffles is positioned 1.5 times the cavity width from the inlet, at the point of maximum swirling intensity. Four rows of sawtooth baffles are arranged sequentially backward, which can divide the airflow into more small vortices and improve mixing efficiency.

[0030] The porous wave baffle 2107 is a honeycomb porous plate that uniformly collects gas and prevents local short circuits. A conical guide cone 2108 with a cone angle of 30° is provided at the outlet of the mixing chamber 2101, which can effectively eliminate outlet eddies and dead zones, avoid gas stagnation in the corners of the chamber, and allow the mixed gas to flow out at a uniform flow rate and concentration.

[0031] The gas pressurization and replenishment branch includes two parallel mixed gas pipelines 25. A third pressure transmitter 22 is installed at the front end of each pipeline 25. The first pipeline is a booster pump branch, connected in series with an oil-free miniature piston booster pump 23 and a fifth solenoid valve 24. The opening of the booster pump 23 and the fifth solenoid valve 24 is controlled by a PLC system, used to boost the mixed gas pressure before output when it is low. The second pipeline is a conventional branch, connected in series with a sixth solenoid valve 26 after the mixed gas pipeline 25. The opening of the sixth solenoid valve 26 is controlled by a PLC system, used for direct output when the mixed gas pressure meets the replenishment requirements. After the outlets of the two pipelines merge, they are sequentially connected to a fourth pressure transmitter 27, a third check valve 29, and an eighth solenoid valve 30. The fourth pressure transmitter 27 is used to monitor the output pressure in real time. The third check valve 29 prevents gas from flowing back into the branch from the switchgear chamber. The third check valve 29 is connected in parallel with the seventh solenoid valve 28. When evacuating the pipeline, the seventh solenoid valve 28 is opened to form a passage, avoiding incomplete vacuum evacuation due to the opening pressure of the third check valve 29. The opening of the eighth solenoid valve 30 is controlled by the PLC system and is used to open or close the gas charging branch. The merged pipeline finally leads to the outlet of the gas replenishment device. The outlet is equipped with a quick connector to adapt to the gas replenishment interface of common power equipment or experimental equipment. The pipeline vacuum system includes an oil-free miniature rotary vane vacuum pump 33, a solenoid valve assembly 32, four vacuum branches, a fourth one-way valve 34, and a vacuum pump outlet 35. One end of the pipeline vacuum system is connected to the inlet of the vacuum pump 33, and the other end branches into four vacuum branches via a multi-connector straight pipe section: the first vacuum branch connects to the pipe between the first one-way valve 5 and the temperature equalizer 14 in the sulfur hexafluoride charging line; the second connects to the pipe between the second one-way valve 12 and the temperature equalizer 14 in the nitrogen charging line; the third connects to the pipe between the gas mixing device 21 and the mixed gas pipeline 25; and the fourth connects to the pipe between the third one-way valve 29 and the make-up gas outlet. Each vacuum branch is equipped with a solenoid control valve, integrated into a solenoid valve assembly 32 module, which is opened or closed by a control signal. The pipeline vacuum system is equipped with a second solenoid valve 4, a fourth solenoid valve 11, and a seventh solenoid valve 28. When the pipeline is evacuated, the inherent opening pressure of each check valve can be eliminated from affecting the vacuum level. The above combination can achieve full pipeline vacuuming, with the final vacuum level not exceeding 50Pa.

[0032] The device's workflow consists of five stages: The first stage is the pipeline vacuum treatment stage. First, connect the gas lines of sulfur hexafluoride cylinder 1, the first pressure reducing valve 2, nitrogen cylinder 8, and the second pressure reducing valve 9. Connect the charging interface 31 to the interface of the gas chamber of the switch to be charged. Then, open the solenoid valve group 32, the second solenoid valve 4, the fourth solenoid valve 11, the seventh solenoid valve 28, and the vacuum pump 33 to evacuate the entire pipeline. The pipeline vacuum status is fed back to the PLC system by the vacuum gauge 6, which displays the vacuum degree in real time. Once the pipeline vacuum degree reaches 50 Pa, continue evacuation for 30 minutes. After shutdown, check the pipeline sealing based on the pressure change of the vacuum gauge 6. After the pipeline vacuum treatment stage is completed, close the vacuum pump 33 and all valves in the valve group.

[0033] The second stage is the gas path adjustment stage. The valves of sulfur hexafluoride cylinder 1 and nitrogen cylinder 8 are opened to allow the gas to be injected into the corresponding gas equalization buffer device 17 in their respective gas paths. The pressure of the two gas paths is adjusted to the preset value by the first pressure reducing valve 2 and the second pressure reducing valve 9 respectively. The pressure value is monitored in real time by the first pressure transmitter 15, the second pressure transmitter 16 and the differential pressure gauge 18 to ensure that the pressure error between the two gas paths does not exceed 0.01MPa.

[0034] The third stage is the pressure balancing and gas mixing stage. The mixing gas ratio is set on the PLC human-machine interface, such as sulfur hexafluoride: nitrogen = 3:7. After the mixing gas ratio is set and the pressure difference value of the gas equalization buffer device 17 meets the requirements, the PLC system controls the first mass flow controller 19 and the second mass flow controller 20 to start synchronously. The proportional gas regulated by the first mass flow controller 19 and the second mass flow controller 20 is injected into the gas mixing device 21 for thorough mixing.

[0035] The fourth stage is the gas replenishment and output stage. The mixed gas enters the mixed gas pipeline 25, and the output pressure is monitored by the fourth pressure transmitter 27. If the pressure is higher than the gas replenishment target pressure by more than 0.2 MPa, the sixth solenoid valve 26 is opened and the fifth solenoid valve 24 is closed. The mixed gas is output to the gas replenishment interface through the conventional branch. If the pressure is lower than the gas replenishment target pressure by more than 0.2 MPa, the sixth solenoid valve 26 is closed and the fifth solenoid valve 24 is opened. The booster pump 23 is started. The gas is pressurized by the booster pump branch and then merged with the gas in the conventional branch. The mixed gas is then charged to the gas chamber of the switchgear through the third one-way valve 29 until the gas pressure of the gas replenishment target reaches the preset value.

[0036] The fifth stage is the shutdown stage. After the gas pressure in the gas chamber of the switching equipment reaches the preset value, the PLC system issues an audible and visual prompt. First, the first solenoid valve 3 and the third solenoid valve 10 are closed. The pressure of the sulfur hexafluoride buffer tank in the gas equalization buffer device 17 is monitored by the first pressure transmitter 15. After the pressure of the sulfur hexafluoride buffer tank is drawn down to normal pressure by the booster pump 23, the eighth solenoid valve 30 and the booster pump 23 are closed. The device shuts down, and the gas replenishment operation is completed.

[0037] After the device is shut down, the first solenoid valve 3, the third solenoid valve 10 and the eighth solenoid valve 30 remain in a normally closed state to ensure that there is no water vapor corrosion in the device pipeline.

[0038] This embodiment achieves portability through a compact integrated design. It employs a gas equalization buffer device and a mass flow controller to collaboratively control gas pressure and flow, while a specially structured gas mixing device ensures mixing accuracy. Parallel gas boosting and replenishment branches adapt to different pressure requirements, and a full-pipeline vacuum system prevents residual gas from affecting mixing purity. Oil-free components ensure gas cleanliness, making it widely applicable to scenarios such as electrical equipment insulation gas replenishment and laboratory gas mixing.

Claims

1. A portable sulfur hexafluoride and nitrogen mixing and replenishment device, characterized in that, Includes a chassis, wherein the chassis is provided with an inflation air path, a gas mixing device (21) and a gas pressurization and replenishment branch that are connected sequentially along the gas flow direction; The gas filling circuit includes a sulfur hexafluoride gas filling circuit and a nitrogen gas filling circuit arranged in parallel. The gas mixing device (21) includes a mixing chamber (2101), a sulfur hexafluoride gas inlet (2102) is provided at the left end of the mixing chamber (2101), a porous jet plate (2105), a sawtooth baffle group (2106) and a porous corrugated baffle (2107) are arranged sequentially from left to right inside the mixing chamber (2101), a nitrogen gas inlet (2103) is provided on the side wall of the mixing chamber (2101) in the area between the porous jet plate (2105) and the sawtooth baffle group (2106), and a mixed gas outlet (2109) is provided at the right end of the mixing chamber (2101). The gas pressurization supplementary branch includes a booster pump branch and a conventional branch connected in parallel.

2. The portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 1, characterized in that, The mixing chamber (2101) has a side cutout (2104) on the upper side wall. A buffer zone is provided outside the side cutout (2104). The mixing chamber (2101) and the buffer zone are connected through the side cutout (2104). The nitrogen gas inlet (2103) is located on the outer side of the buffer zone.

3. The portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 1, characterized in that, The plane of each sawtooth baffle in the sawtooth baffle group (2106) is at an angle of 60° with the airflow direction, which forces the airflow to deflect laterally (both horizontally and longitudinally) at the same time, forming three-dimensional turbulence. The sawtooth directions of two adjacent layers of sawtooth baffles are opposite.

4. The portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 1, characterized in that, The mixing cavity (2101) has a flat structure with a length-to-width ratio of 15:1 and a thickness-to-width ratio of 1:3 to 1:

5.

5. A portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 1, characterized in that, Each gas filling circuit includes a gas cylinder, a pressure reducing valve, a normally closed solenoid valve, a check valve, a pressure transmitter, a gas equalization buffer device (17), and a flow controller connected in sequence; the gas equalization buffer devices (17) in the two gas circuits are connected together by a differential pressure gauge (18) for coupling the two gas equalization buffer devices.

6. A portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 5, characterized in that, The pipeline section between the one-way valve and the pressure transmitter in each gas charging line is connected to the temperature equalizer (14); the temperature equalizer (14) is equipped with a gas heat exchange pipeline that first exchanges heat in the reverse direction and then equalizes the temperature in the same direction.

7. A portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 6, characterized in that, The chassis is also equipped with a full-pipeline vacuum system, which includes a vacuum pump (33) connected to multiple parallel vacuum branches.

8. A portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 7, characterized in that, The vacuuming branch includes: the pipeline between the one-way valve and the temperature equalizer (14) in each inflation gas path, the pipeline between the gas mixing device (21) and the gas pressurization and replenishment branch, and the pipeline between the gas pressurization and replenishment branch and the inflation port (31).

9. A portable sulfur hexafluoride and nitrogen mixing and replenishment device according to claim 8, characterized in that, Each of the vacuuming branches is equipped with a control valve, and all control valves form a solenoid valve group (32). The solenoid valve group (32) controls all vacuuming branches to open or close synchronously.

10. A method for filling the gas chamber of a switchgear using the portable sulfur hexafluoride and nitrogen mixing and replenishing device as described in claim 9, characterized in that, Specifically as follows: Step 1: Connect the gas cylinder, pressure reducing valve, filling interface and the gas chamber of the switch to be filled, close the gas cylinder valve, and turn on the vacuum pump (33) to evacuate the entire pipeline; Step 2: Open the gas cylinder valve to inject gas into the corresponding gas equalization buffer device (17) in each gas path. Adjust the pressure of the two gas paths to the preset value through the pressure reducing valve. Monitor the pressure value in real time through the pressure transmitter and differential pressure gauge (18). Step 3: Turn on the mass flow controller and inject the proportioned gas adjusted by the mass flow controller into the gas mixing device (21) for mixing; Step 4: After replenishing the gas through the gas pressurization and replenishment branch, the mixed gas is filled into the gas chamber of the switchgear; Step 5: After the gas pressure in the gas chamber of the switchgear reaches the preset value, first close the solenoid valves in the two parallel gas circuits, monitor the pressure of the sulfur hexafluoride buffer tank in the gas equalization buffer device (17) through the pressure transmitter, and after the pressure of the sulfur hexafluoride buffer tank is drawn down to the normal pressure by the booster pump, turn off the booster pump, stop the device, and complete the gas replenishment operation.

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