An SF6 / CF4 mixed gas preparation and direct filling device and method with real-time correction of mixing ratio

Abstract

An SF6 / CF4 mixed gas preparation and direct filling device and method with real-time correction of the mixing ratio, belonging to the technical field of operation and maintenance of electrical equipment, which solves the problem of stratification of SF6 gas and CF4 gas existing in the SF6 / CF4 mixed gas filling and supplementing operation; the input flow rates of SF6 and CF4 gases are controlled by the first and second mass flow controllers. After the input SF6 and CF4 gases enter the buffer tank through the gas mixing nozzle and are mixed evenly, the mixing ratio of the SF6 / CF4 mixed gas is detected by the thermal conductivity detector, and finally filled into the electrical equipment; the gas mixing nozzle effectively mixes the SF6 and CF4 gases evenly, eliminates the stratification phenomenon, makes the detection result of the mixing ratio more credible and has higher accuracy; by controlling the first and second mass flow controllers, the mixing ratio of the SF6 / CF4 mixed gas is adjusted in real time to ensure that the mixing ratio of the filled SF6 / CF4 mixed gas meets the requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of operation, maintenance and repair of electrical equipment, and relates to a direct charging device and method for preparing an SF6 / CF4 mixed gas with real-time correction of the mixing ratio. Background Art

[0002] Due to its good insulation and arc extinguishing performance and the characteristic of not being easily liquefied, the SF6 / CF4 mixed gas has been widely used in northern provinces of China and achieved good application results. With the large-scale application of the SF6 / CF4 mixed gas in electrical equipment, the supporting operation, maintenance and repair technologies and equipment are very lacking and urgently need to be improved. In the aspect of the gas filling and supplementing operation of the SF6 / CF4 mixed gas in electrical equipment, the existing technology adopts the step-by-step gas filling method: first, SF6 gas is filled, and then CF4 gas is filled. It is difficult to control the mixing ratio of the mixed gas; moreover, the gas filled into the electrical equipment in steps has a stratification phenomenon and requires several months to be fully mixed under natural diffusion. During this period, the insulation and arc extinguishing performance of the mixed gas does not meet the requirements. Generally speaking, the existing gas filling and supplementing operation technology for the SF6 / CF4 mixed gas has the following disadvantages: 1) There is a stratification phenomenon of the SF6 / CF4 mixed gas filled into the electrical equipment; 2) The mixing ratio result measured in the stratified state is not credible; 3) When there is an error in the mixing ratio, it cannot be corrected in real time and effectively. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: how to eliminate the stratification phenomenon of SF6 gas and CF4 gas existing during the gas filling and supplementing operation of the SF6 / CF4 mixed gas.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] An SF6 / CF4 mixed gas preparation and direct filling device with real-time correction of the mixing ratio, comprising: an SF6 inlet pipeline, a CF4 inlet pipeline, a gas mixing nozzle (20), a buffer tank (9), a proportional valve (12), a mixing ratio detection branch pipeline, and a main filling pipeline; the output end of the SF6 inlet pipeline and the output end of the CF4 inlet pipeline converge and then are connected to the input end of the gas mixing nozzle (20), the input end of the gas mixing nozzle (20) is arranged on the outer wall of the buffer tank (9), the output end of the gas mixing nozzle (20) is arranged inside the buffer tank (9), the output end of the buffer tank (9) is connected to the input end of the proportional valve (12), the output end of the proportional valve (12) is respectively connected to the input ends of the mixing ratio detection branch pipeline and the main filling pipeline, and the output end of the mixing ratio detection branch pipeline is connected to the main filling pipeline; a first mass flow controller (4) is arranged in the SF6 inlet pipeline for controlling the input flow of SF6 gas, a second mass flow controller (8) is arranged in the CF4 inlet pipeline for controlling the input flow of CF4 gas, and a thermal conductivity detector (14) is arranged in the mixing ratio detection branch pipeline for real-time detecting the mixing ratio of the SF6 / CF4 mixed gas;

[0006] The gas mixing nozzle (20) comprises: an inlet pipe (201), a conical cavity (202), a cover plate (203), and capillary drainage tubes (204); one end of the inlet pipe (201) serves as the input end of the gas mixing nozzle (20) and is connected to the output ends of the SF6 inlet pipeline and the CF4 inlet pipeline; the other end of the inlet pipe (201) is integrally formed with the input port of the conical cavity (202), the cover plate (203) is sealingly covered on the output port of the conical cavity (202), a plurality of holes are uniformly formed in the cover plate (203), one ends of the plurality of capillary drainage tubes (204) are installed in the holes formed in the cover plate (203), and the other ends of the plurality of capillary drainage tubes (204) are all inclined towards the central axis of the gas mixing nozzle (20).

[0007] Further, the SF6 inlet pipeline further comprises: a first heat exchanger (2), a first solenoid valve (3); one end of the first heat exchanger (2) serves as the input end of the SF6 inlet pipeline, the other end of the first heat exchanger (2) is connected to one end of the first solenoid valve (3), the other end of the first solenoid valve (3) is connected to the input end of the first mass flow controller (4), and the output end of the first mass flow controller (4) serves as the output end of the SF6 inlet pipeline and is connected to the input end of the gas mixing nozzle (20).

[0008] Further, the CF4 intake pipeline further includes: a second heat exchanger (6) and a second solenoid valve (7); one end of the second heat exchanger (6) serves as the input end of the CF4 intake pipeline, the other end of the second heat exchanger (6) is connected to one end of the second solenoid valve (7), the other end of the second solenoid valve (7) is connected to the input end of the second mass flow controller (8), and the output end of the second mass flow controller (8) serves as the output end of the CF4 intake pipeline and is connected to the input end of the gas mixing nozzle (20).

[0009] Further, the main charging pipeline includes: a compressor (16) and a third solenoid valve (17); the output end of the proportional valve (12) is connected to the input end of the compressor (16), and the output end of the compressor (16) is connected to one end of the third solenoid valve (17).

[0010] Further, the mixing ratio detection branch pipeline further includes: an adjusting needle valve (13); the input end of the adjusting needle valve (13) is connected to the output end of the proportional valve (12), the output end of the adjusting needle valve (13) is connected to the input end of the thermal conductivity detector (14), and the output end of the thermal conductivity detector (14) is connected to the input end of the compressor (16).

[0011] Further, the SF6 / CF4 mixed gas preparation and direct charging device with real-time mixing ratio correction further includes: a vacuum pumping pipeline, and the vacuum pumping pipeline includes: a vacuum pump (15) and a fourth solenoid valve (21); one end of the fourth solenoid valve (21) is connected between the proportional valve (12) and the compressor (16), and the other end of the fourth solenoid valve (21) is connected to the input end of the vacuum pump (15).

[0012] Further, a pressure sensor (10) and a temperature sensor (11) are installed on the top of the buffer tank (9).

[0013] A method applied to the SF6 / CF4 mixed gas preparation and direct charging device with real-time mixing ratio correction controls the input flow rates of SF6 gas and CF4 gas through the first mass flow controller (4) and the second mass flow controller (8). After the input SF6 gas and CF4 gas enter the buffer tank (9) through the gas mixing nozzle (20) and are mixed evenly, when the thermal conductivity detector (14) detects that the mixing ratio of the SF6 / CF4 mixed gas meets the requirements, the SF6 / CF4 mixed gas is charged into the electrical equipment through the main charging pipeline.

[0014] Further, the method for real-time correction of the mixing ratio of the SF6 / CF4 mixed gas is as follows: It is known that the mixing ratio of the SF6 gas and the CF4 gas detected by the thermal conductivity detector (14) is A:B. At this time, the flow rates of the SF6 gas and the CF4 gas are Q1:Q2 respectively. If the proportion of the SF6 gas is on the high side, the flow rate Q1 of the first mass flow controller (4) is adjusted to B / A times the original value, and Q2 remains unchanged. On the contrary, if the CF4 is on the high side, the flow rate Q2 of the second mass flow controller (8) is adjusted to A / B times the original value, and Q1 remains unchanged.

[0015] The advantages of the present invention are as follows:

[0016] The technical solution of the present invention controls the input flow rates of the SF6 gas and the CF4 gas through the first mass flow controller (4) and the second mass flow controller (8). The input SF6 gas and CF4 gas enter the buffer tank (9) through the gas mixing nozzle (20) and are mixed evenly. Then, the mixing ratio of the SF6 / CF4 mixed gas is detected by the thermal conductivity detector (14), and finally, it is filled into the electrical equipment. The gas mixing nozzle (20) can effectively mix the SF6 and CF4 gases evenly, eliminate the layering phenomenon, and make the detection result of the mixing ratio more credible and the accuracy higher. By controlling the first mass flow controller (4) and the second mass flow controller (8), the mixing ratio of the SF6 / CF4 mixed gas can be adjusted in real time to ensure that the mixing ratio of the filled SF6 / CF4 mixed gas meets the requirements. Description of the Drawings

[0017] Figure 1 is the structural diagram of the SF6 / CF4 mixed gas preparation and direct filling device for real-time correction of the mixing ratio in the first embodiment of the present invention;

[0018] Figure 2 is the structural diagram of the gas mixing nozzle of the SF6 / CF4 mixed gas preparation and direct filling device for real-time correction of the mixing ratio in the first embodiment of the present invention. Detailed Embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments:

[0021] Embodiment 1

[0022] AsFigure 1 As shown in the figure, a direct filling device for preparing SF6 / CF4 mixed gas with real-time correction of mixing ratio includes: a first pressure reducing valve (1), a first heat exchanger (2), a first solenoid valve (3), a first mass flow controller (4), a second pressure reducing valve (5), a second heat exchanger (6), a second solenoid valve (7), a second mass flow controller (8), a buffer tank (9), a pressure sensor (10), a temperature sensor (11), a proportional valve (12), an adjusting needle valve (13), a thermal conductivity detector (14), a vacuum pump (15), a compressor (16), a third solenoid valve (17), a first exhaust port (18), a second exhaust port (19), a gas mixing nozzle (20), and a fourth solenoid valve (21).

[0023] One end of the first pressure reducing valve (1) is hermetically connected to the SF6 cylinder, the other end of the first pressure reducing valve (1) is hermetically connected to one end of the first heat exchanger (2), the other end of the first heat exchanger (2) is hermetically connected to one end of the first solenoid valve (3), and the other end of the first solenoid valve (3) is connected to the input end of the first mass flow controller (4); one end of the second pressure reducing valve (5) is hermetically connected to the CF4 cylinder, the other end of the second pressure reducing valve (5) is hermetically connected to one end of the second heat exchanger (6), the other end of the second heat exchanger (6) is hermetically connected to one end of the second solenoid valve (7), and the other end of the second solenoid valve (7) is connected to the input end of the second mass flow controller (8).

[0024] The gas mixing nozzle (20) is hermetically installed on the side wall of the buffer tank (9), and the output ends of the first mass flow controller (4) and the second mass flow controller (8) are both hermetically connected to the input end of the gas mixing nozzle (20); the pressure sensor (10) and the temperature sensor (11) are hermetically installed on the top of the buffer tank (9), the output port of the buffer tank (9) is hermetically connected to the input end of the proportional valve (12), the output end of the proportional valve (12) is hermetically connected to the input end of the compressor (16), the output end of the compressor (16) is hermetically connected to one end of the third solenoid valve (17), and the other end of the third solenoid valve (17) is hermetically connected to the first exhaust port (18).

[0025] The input end of the adjusting needle valve (13) is hermetically connected to the output end of the proportional valve (12), the output end of the adjusting needle valve (13) is hermetically connected to the input end of the thermal conductivity detector (14), the output end of the thermal conductivity detector (14) is hermetically connected to the input end of the compressor (16), one end of the fourth solenoid valve (21) is hermetically connected between the proportional valve (12) and the compressor (16), the other end of the fourth solenoid valve (21) is hermetically connected to the input end of the vacuum pump (15), and the output end of the vacuum pump (15) is hermetically connected to the second exhaust port (19).

[0026] AsFigure 2 As shown, the gas mixing nozzle (20) includes: an air inlet pipe (201), a conical cavity (202), a cover plate (203), and a capillary drainage pipe (204); the air inlet pipe (201) is integrally formed with the input port of the conical cavity (202), the cover plate (203) is sealed on the output port of the conical cavity (202), and a plurality of holes are evenly formed on the cover plate (203). One ends of the plurality of capillary drainage pipes (204) are installed in the holes formed on the cover plate (203), and the other ends of the plurality of capillary drainage pipes (204) are all inclined towards the central axis of the gas mixing nozzle (20), so that the SF6 gas and CF4 gas ejected from the capillary drainage pipes (204) can be better mixed, improving the mixing efficiency.

[0027] The working process of the device is as follows:

[0028] (1) Vacuum pumping: Initially, all valves are in the closed state. The device is hermetically connected to the equipment to be inflated through the first exhaust port (18). At this time, the first solenoid valve (3), the second solenoid valve (7), the proportional valve (12), the regulating needle valve (13), and the fourth solenoid valve (21) are opened, and the vacuum pump (15) is started to pump vacuum for the device. After the vacuum pumping is completed, all valves are closed.

[0029] (2) Open the first pressure reducing valve (1) and the second pressure reducing valve (5), control the pressure at 0.8 MPa, and start the first heat exchanger (2) and the second heat exchanger (6) to heat the SF6 gas and CF4 gas output from the SF6 cylinder and the CF4 cylinder; heating can improve the charging and replenishing accuracy and avoid excessive gas filling; in addition, the mixing ratio detection accuracy is related to the gas temperature. The closer it is to the calibration temperature of 20 °C, the lower the detection result error.

[0030] (3) Open the first solenoid valve (3) and the second solenoid valve (7), control the first mass flow controller (4) and the second mass flow controller (8) to output SF6 and CF4 gases respectively according to the set flow rate, and the output SF6 and CF4 gases enter the buffer tank (9) through the gas mixing nozzle (20) and are evenly mixed therein.

[0031] (4) The pressure sensor (10) and the temperature sensor (11) respectively monitor the gas pressure and temperature in the buffer tank (9). If the pressure is too high, increase the aperture of the proportional valve (12) to allow more gas to flow to the rear end and reduce the pressure in the buffer tank (9); otherwise, decrease the aperture of the proportional valve (12) to keep the gas pressure in the buffer tank (9) stable. If the temperature is lower than 20 °C, increase the power of the first heat exchanger (2) and the second heat exchanger (6); otherwise, decrease the power of the first heat exchanger (2) and the second heat exchanger (6) to keep the gas temperature stable at 20 °C.

[0032] (5) Open the regulating needle valve (13), control the flow rate at 300 ml / min. A part of the SF6 / CF4 mixed gas output from the proportional valve (12) is input into the thermal conductivity detector (14) through the regulating needle valve (13) to detect the mixing ratio of the SF6 / CF4 mixed gas. If the mixing ratio meets the requirements, open the third solenoid valve (17) and start the compressor (16) to pressurize and supplement the SF6 / CF4 mixed gas into the electrical equipment.

[0033] (6) The mixing ratio of the SF6 / CF4 mixed gas can be corrected in real time according to the following method: It is known that the mixing ratio of the SF6 gas and the CF4 gas detected by the thermal conductivity detector (14) is A:B, and the flow rates of the SF6 gas and the CF4 gas are Q1:Q2 at this time. If the proportion of the SF6 gas is too high, adjust the flow rate Q1 of the first mass flow controller (4) to B / A times of the original, and Q2 remains unchanged; on the contrary, if the CF4 is too high, adjust the flow rate Q2 of the second mass flow controller (8) to A / B times of the original, and Q1 remains unchanged.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A direct filling device for preparing SF6 / CF4 mixed gas with real-time correction of mixing ratio, characterized in that, Comprising: SF6 intake pipeline, CF4 intake pipeline, gas mixing nozzle (20), buffer tank (9), proportional valve (12), mixing ratio detection branch pipeline, main charging pipeline; the output end of the SF6 intake pipeline and the output end of the CF4 intake pipeline converge and then are connected to the input end of the gas mixing nozzle (20), the input end of the gas mixing nozzle (20) is arranged on the outer wall of the buffer tank (9), the output end of the gas mixing nozzle (20) is arranged inside the buffer tank (9), the output end of the buffer tank (9) is connected to the input end of the proportional valve (12), the output end of the proportional valve (12) is respectively connected to the input ends of the mixing ratio detection branch pipeline and the main charging pipeline, and the output end of the mixing ratio detection branch pipeline is connected in the main charging pipeline; a first mass flow controller (4) is arranged in the SF6 intake pipeline for controlling the input flow of SF6 gas, a second mass flow controller (8) is arranged in the CF4 intake pipeline for controlling the input flow of CF4 gas, and a thermal conductivity detector (14) is arranged in the mixing ratio detection branch pipeline for real-time detecting the mixing ratio of the SF6 / CF4 mixed gas; The gas mixing nozzle (20) comprises: an intake pipe (201), a conical cavity (202), a cover plate (203), capillary drainage pipes (204); one end of the intake pipe (201) serves as the input end of the gas mixing nozzle (20) and is connected to the output end of the SF6 intake pipeline and the output end of the CF4 intake pipeline; the other end of the intake pipe (201) is integrally formed with the input port of the conical cavity (202), the cover plate (203) is sealingly covered on the output port of the conical cavity (202), a plurality of holes are uniformly formed in the cover plate (203), one ends of the plurality of capillary drainage pipes (204) are installed in the holes formed in the cover plate (203), and the other ends of the plurality of capillary drainage pipes (204) are all inclined towards the central axis of the gas mixing nozzle (20); The SF6 intake pipeline further comprises: a first heat exchanger (2), a first solenoid valve (3); one end of the first heat exchanger (2) serves as the input end of the SF6 intake pipeline, the other end of the first heat exchanger (2) is connected to one end of the first solenoid valve (3), the other end of the first solenoid valve (3) is connected to the input end of the first mass flow controller (4), and the output end of the first mass flow controller (4) serves as the output end of the SF6 intake pipeline and is connected to the input end of the gas mixing nozzle (20); The CF4 intake pipeline further comprises: a second heat exchanger (6), a second solenoid valve (7); one end of the second heat exchanger (6) serves as the input end of the CF4 intake pipeline, the other end of the second heat exchanger (6) is connected to one end of the second solenoid valve (7), the other end of the second solenoid valve (7) is connected to the input end of the second mass flow controller (8), and the output end of the second mass flow controller (8) serves as the output end of the CF4 intake pipeline and is connected to the input end of the gas mixing nozzle (20); The described main charging pipeline includes: a compressor (16) and a third solenoid valve (17); the output end of the proportional valve (12) is connected to the input end of the compressor (16), and the output end of the compressor (16) is connected to one end of the third solenoid valve (17). The described mixing ratio detection branch pipeline further includes: an adjusting needle valve (13); the input end of the adjusting needle valve (13) is connected to the output end of the proportional valve (12), the output end of the adjusting needle valve (13) is connected to the input end of the thermal conductivity detector (14), and the output end of the thermal conductivity detector (14) is connected to the input end of the compressor (16).

2. The direct filling device for preparing SF6 / CF4 mixed gas with real-time correction of mixing ratio according to claim 1, characterized in that, It further includes: a vacuum pumping pipeline, and the described vacuum pumping pipeline includes: a vacuum pump (15) and a fourth solenoid valve (21); one end of the fourth solenoid valve (21) is connected between the proportional valve (12) and the compressor (16), and the other end of the fourth solenoid valve (21) is connected to the input end of the vacuum pump (15).

3. The direct filling device for preparing SF6 / CF4 mixed gas with real-time correction of mixing ratio according to claim 1, characterized in that, A pressure sensor (10) and a temperature sensor (11) are installed at the top of the buffer tank (9).

4. A method for a direct filling device for preparing an SF6 / CF4 mixed gas with real-time correction of the mixing ratio according to any one of claims 1 to 3, characterized in that, The input flow rates of SF6 gas and CF4 gas are controlled by the first mass flow controller (4) and the second mass flow controller (8). After the input SF6 gas and CF4 gas enter the buffer tank (9) through the gas mixing nozzle (20) and are mixed evenly, when the thermal conductivity detector (14) detects that the mixing ratio of the SF6 / CF4 mixed gas meets the requirements, the SF6 / CF4 mixed gas is charged into the electrical equipment through the main charging pipeline.

5. The method according to claim 4, wherein The method for real-time correction of the mixing ratio of the described SF6 / CF4 mixed gas is as follows: Given that the mixing ratio of SF6 gas and CF4 gas detected by the thermal conductivity detector (14) is A:B, and the flow rates of SF6 gas and CF4 gas are Q1:Q2 at this time; if the proportion of SF6 gas is on the high side, adjust the flow rate Q1 of the first mass flow controller (4) to B / A times the original value, and Q2 remains unchanged; conversely, if the proportion of CF4 gas is on the high side, adjust the flow rate Q2 of the second mass flow controller (8) to A / B times the original value, and Q1 remains unchanged.

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