Gas filling method of an environmentally friendly gas-filled cabinet

Abstract

The application discloses a kind of gas filling methods of environmental protection gas-filled cabinet, comprising: continuously heating to sealing gas chamber, so that the inside of the sealing gas chamber reaches and maintains the temperature condition of moisture desorption;Alternately implement vacuumizing operation and gas injection operation in the inside of the sealing gas chamber, the vacuumizing operation is divided into the pressure reduction phase and the pressure maintaining phase alternately executed;During the execution of any the pressure reduction phase, the real-time temperature data at the internal components are obtained;When the real-time temperature data drops to the preset temperature, the pressure drop rate of the current pressure reduction phase is reduced, and / or, the maintenance time of adjacent next pressure maintaining phase is extended;Finally, the sealing gas chamber is filled with environmentally friendly insulating gas, mechanical vibration is applied and leakage rate detection is carried out.The application cuts off the moisture icing condition in the vacuumizing process by adaptive adjustment, realizes the complete drying of the equipment inside, and guarantees the long-term insulation safety.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment manufacturing and assembly technology, and more specifically to a gas filling method for an environmentally friendly gas-filled cabinet. Background Technology

[0002] As a new generation of power transmission and distribution equipment, environmentally friendly gas-insulated switchgear relies primarily on environmentally friendly insulating gas for insulation. Before the environmentally friendly gas-insulated switchgear is manufactured and assembled and ready to be filled with environmentally friendly insulating gas, the internal sealed gas chamber must undergo extremely rigorous dehydration and drying treatment to prevent residual moisture from causing insulation degradation, partial discharge, or even equipment breakdown during long-term operation.

[0003] Existing dehydration processes typically employ high-power vacuum pumps to directly vacuum the sealed chamber, causing the moisture to vaporize and be extracted under low pressure. However, moisture absorbs a significant amount of latent heat during vaporization, leading to a rapid temperature drop inside the sealed chamber, particularly around internal components. If the pressure drop during vacuuming is too rapid, the temperature at the internal components will quickly fall below the freezing point of water, causing the remaining liquid water to directly transform into solid ice. Solid ice sublimates very slowly under vacuum, making it extremely difficult to remove effectively using conventional vacuuming methods. This not only severely delays the production cycle of the environmentally friendly gas-insulated switchgear but also results in solid ice remaining in the sealed chamber after drying. When the switchgear is put into operation and the temperature rises, this residual solid ice melts and evaporates, causing the moisture content of the environmentally friendly insulating gas inside the sealed chamber to exceed the standard, posing a significant threat to the safe and stable operation of the power grid. Summary of the Invention

[0004] The main objective of this invention is to provide a gas filling method for an environmentally friendly gas-filled cabinet, in order to solve the technical problem that in the existing dehydration process, when the pressure drops too quickly during the vacuuming operation, the temperature at the components inside the sealed gas chamber drops sharply, causing water to freeze, which in turn prevents the water from being completely removed, ultimately resulting in excessive moisture in the environmentally friendly insulating gas.

[0005] The present invention provides a gas filling method for an environmentally friendly gas-filled cabinet, wherein the environmentally friendly gas-filled cabinet includes a sealed gas chamber for encapsulating internal components, and the gas filling method includes the following steps: S1. The sealed air chamber is continuously heated to bring the temperature conditions for moisture desorption inside the sealed air chamber to a level that is maintained. S2. Alternately perform vacuuming and gas injection operations inside the sealed gas chamber; Specifically, during the vacuuming operation, the operation is divided into multiple alternating pressure reduction and pressure holding phases until the absolute pressure in the sealed chamber drops to a first preset pressure and is maintained for a first preset duration. During any of the pressure reduction phases, real-time temperature data at the internal components is acquired. When the real-time temperature data drops to a preset temperature, the pressure reduction rate of the current pressure reduction phase is reduced, and / or the holding time of the next adjacent pressure holding phase is extended, so that the heat transferred into the sealed chamber in S1 is not less than the heat absorbed by the vaporization of moisture in the sealed chamber, thereby maintaining the temperature at the internal components above the water freezing temperature. The preset temperature is higher than the freezing temperature of the water; When performing the gas injection operation, dry gas is injected into the sealed gas chamber until the absolute pressure in the sealed gas chamber rises to the second preset pressure and is maintained for the second preset duration; The first preset pressure is less than the second preset pressure; During the vacuuming operation, the moisture content in the gas extracted from the sealed chamber is monitored in real time. When the moisture content reaches the preset drying standard, the vacuuming operation, the gas injection operation, and the continuous heating of the sealed chamber are stopped. S3. Inject environmentally friendly insulating gas into the sealed gas chamber until the pressure inside the sealed gas chamber reaches the preset working pressure.

[0006] Preferably, the preset drying standard is: The micro-moisture content detected during the vacuuming operation was lower than the first preset threshold and the difference was less than the second preset threshold in two consecutive tests.

[0007] Preferably, the temperature conditions for moisture desorption are as follows: The temperature inside the sealed air chamber is between 60°C and 70°C.

[0008] Preferably, the preset temperature is set to 1℃~5℃.

[0009] Preferably, the first preset pressure is 30Pa~70Pa; the second preset pressure is 0.11MPa~0.15MPa.

[0010] Preferably, the process of filling the sealed gas chamber with environmentally friendly insulating gas includes: The process of filling with environmentally friendly insulating gas is divided into multiple filling stages with successively decreasing filling rates; During the execution of any of the filling stages, the temperature change rate at the sealing joint of the sealed gas chamber is obtained; when the absolute value of the temperature change rate is greater than a preset temperature change rate threshold, the current filling stage is paused until the temperature at the sealing joint of the shell rises back to a preset safe temperature, and then the paused filling stage is resumed.

[0011] Preferably, the process after S3 includes: S4. Apply mechanical vibration to the environmentally friendly gas-filled cabinet, and during this process, detect the leakage rate at the sealing joint of the sealed gas chamber shell.

[0012] Preferably, the environmentally friendly insulating gas is selected from any one of dry compressed air, nitrogen, a mixture of fluorinated nitric acid and carbon dioxide, or a mixture of fluorinated nitric acid and nitrogen.

[0013] One or more technical solutions provided in this invention have at least the following technical effects or advantages: This invention changes the traditional continuous vacuuming method by dividing the vacuuming operation into multiple alternating pressure reduction and pressure holding phases. During any pressure reduction phase, real-time temperature data at the internal components is acquired, and when the temperature drops to a preset level, the pressure reduction rate of the current pressure reduction phase is dynamically reduced, and / or the holding time of the next adjacent pressure holding phase is extended, precisely suppressing the rate of moisture vaporization. This adaptive control mechanism ensures that the heat transferred into the sealed chamber in S1 is not less than the heat absorbed by moisture vaporization, thereby maintaining the temperature at the internal components above the freezing temperature of moisture and preventing the conditions for moisture to transform into solid ice.

[0014] Relying on the aforementioned anti-icing heat balance mechanism, the moisture in the sealed gas chamber remains in a gaseous or liquid state that is easily extracted. Combined with continuous heating and alternating gas injection operations to dilute and replace the precipitated water vapor, this invention significantly improves the moisture removal efficiency within the sealed gas chamber, preventing solid ice residue from remaining on internal components. This fundamentally eliminates the phenomenon of excessive moisture in the environmentally friendly insulating gas after the environmentally friendly gas-filled switchgear is put into operation and the temperature rises, due to the melting and evaporation of residual solid ice, thus ensuring the long-term insulation reliability of the power grid equipment. Attached Figure Description

[0015] Figure 1 This is an overall flowchart of a gas filling method for an environmentally friendly gas-filled cabinet provided in an embodiment of the present invention; Figure 2 This is a flowchart of the adaptive control logic for performing a vacuuming operation, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram illustrating the dynamic change of the absolute pressure inside the sealed gas chamber over time, as provided in an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0017] like Figure 1 As shown, this embodiment of the invention provides a gas filling method for an environmentally friendly gas-insulating switchgear. Before actual assembly and filling, the sealed inner wall and the surface of the internal components of the environmentally friendly gas-insulating switchgear may have trace amounts of moisture adhering to them. The method of this embodiment aims to completely remove this moisture and safely fill it with environmentally friendly insulating gas, specifically including the following steps.

[0018] Step S1: Continuously heat the sealed gas chamber to achieve and maintain the temperature conditions for moisture desorption inside the sealed gas chamber. In practice, this heating operation preferably uses a flexible PTC silicone heating blanket wrapped around the outside of the environmentally friendly gas-filled cabinet for contact heat transfer without dead angles, or utilizes a constant-temperature hot air circulation system to supply air to the outside of the sealed gas chamber of the environmentally friendly gas-filled cabinet for heating. The temperature conditions for moisture desorption are: the temperature inside the sealed gas chamber is between 60℃ and 70℃ (e.g., preferably stable at 65℃). This specific temperature range provides the initial kinetic energy required for the phase change of the fixed water molecules, making it easier for them to desorb from the surface of the internal components and transform into a free gaseous state.

[0019] Step S2: Alternately perform vacuuming and gas injection operations inside the sealed gas chamber. During the gas injection operation, dry gas is injected into the sealed gas chamber until the absolute pressure inside the sealed gas chamber rises to a second preset pressure, and is maintained at the second preset pressure for a second preset time, before performing the next vacuuming operation. The dry gas is preferably extremely dry high-purity nitrogen (purity ≥99.999%) or dry synthetic air (i.e., an anhydrous mixture of high-purity oxygen and high-purity nitrogen). The second preset time can be set, for example, to 5 to 15 minutes, specifically, maintained for 10 minutes, to allow sufficient diffusion and replacement of residual moisture in the sealed gas chamber with the injected dry gas.

[0020] like Figure 2 and Figure 3As shown, during the vacuuming operation, the operation is divided into multiple alternating pressure reduction and pressure holding phases until the absolute pressure in the sealed chamber drops to a first preset pressure and is maintained at the first preset pressure for a first preset duration before the next gas injection operation is performed. For example, the total number of alternating cycles is set to 4 to 8. The first preset duration can be set to, for example, 20 to 60 minutes, specifically 30 minutes, to ensure that any remaining free water molecules in the sealed chamber under ultimate vacuum are completely removed. The first preset pressure is less than the second preset pressure. The first preset pressure is 30 Pa to 70 Pa; the second preset pressure is 0.11 MPa to 0.15 MPa. In a specific example, the first preset pressure can be set to 50 Pa, and the second preset pressure can be set to 0.12 MPa.

[0021] like Figure 2 As shown in the adaptive control logic, real-time temperature data at the internal components is acquired during the execution of any of the aforementioned pressure reduction stages. In a preferred embodiment of the invention, to minimize localized icing dead zones and ensure the absolute safety and thoroughness of the dewatering process, the aforementioned temperature acquisition and adaptive control mechanism is continuously activated and monitored during the execution of each of the aforementioned pressure reduction stages. That is, the system implements strict closed-loop temperature control for each pressure reduction step of the vacuuming operation. In specific equipment deployment, this data can be acquired in real time using high-precision fiber optic temperature sensors or platinum resistance thermometers (such as PT100) pre-attached to the surface of internal components such as high-voltage energized parts. Under normal operating conditions, the total pressure drop during the depressurization phase is set to 15 kPa to 25 kPa (preferably 20 kPa), and the pressure drop rate during this phase is set to 1.0 kPa / min to 2.0 kPa / min (preferably 1.5 kPa / min). This depressurization phase lasts approximately 13 minutes, and the adjacent pressure holding phase lasts 10 to 15 minutes (preferably 13 minutes). When the real-time temperature data does not drop to the preset temperature, the control system maintains the normal pressure drop rate and the normal holding time. The preset temperature is higher than the freezing temperature of the water, and is set to 1°C to 5°C (preferably 3°C).

[0022] When the real-time temperature data drops to a preset temperature, the pressure drop rate of the current depressurization phase is reduced, and / or the duration of the next adjacent pressure holding phase is extended. For example, to strictly control the heat absorption of moisture vaporization, the system appropriately reduces the total pressure drop of the current depressurization phase (e.g., from the conventional 20 kPa to 10 kPa), and significantly reduces the pressure drop rate of the current depressurization phase from the conventional 1.5 kPa / min to 0.2 kPa / min to 0.4 kPa / min (e.g., preferably set to 0.3 kPa / min). In this case, the time span of the current depressurization phase will be significantly extended (e.g., from the conventional 13 minutes to approximately 33 minutes); simultaneously or optionally, the duration of the next adjacent pressure holding phase is extended from the conventional 13 minutes to 25 minutes to 35 minutes (e.g., preferably set to 30 minutes).

[0023] Combination Figure 3 The schematic diagram of the dynamic change curve of the absolute pressure of the sealed air chamber over time provides a further detailed explanation of the above actions. Figure 3 In the diagram, the vertical axis P represents the absolute pressure inside the sealed chamber, and the horizontal axis t represents the duration of the vacuuming operation. Specifically, P0 is the initial pressure before the start of this vacuuming operation, and P1 is the first preset pressure, which is the target vacuum level to be achieved in this vacuuming cycle. In actual operation, the system starts vacuuming at time t1, and performs the first routine pressure reduction phase during the time period from t1 to t2, during which the absolute pressure inside the sealed chamber decreases smoothly from P0 according to the set routine slope. After reaching time t2, the system stops vacuuming, and performs the first routine pressure holding phase during the time period from t2 to t3.

[0024] Subsequently, at time t3, the system initiates the second depressurization phase. If, at this critical juncture, the real-time temperature data from the sensors has dropped to the preset temperature, the system immediately activates an adaptive intervention mechanism. Specifically, the system first reduces the pressure drop rate during this depressurization phase. Figure 3 The most intuitive manifestation of this is that, starting from time t3, the slope of the actual blood pressure reduction curve is significantly gentler than that of the conventional blood pressure reduction curve without intervention. Figure 3 (The dotted line extending downwards from t3) This slow pressure reduction process continues until it ends at t4. Furthermore, from t4 onwards, the system enters the next adjacent pressure holding phase. If the normal holding time is followed, this pressure holding phase should end at... Figure 3 The pressure holding phase ends at time t5 (as shown in the normal span between t4 and t5); however, under the intervention mechanism, the system significantly extends the duration of this pressure holding phase until time t6, when the pressure holding operation ends. The actual pressure holding period is from t4 to t6. After time t6, the system continues to perform subsequent alternating operations until the pressure finally drops to the target first preset pressure P1.

[0025] Through the above Figure 3 The control operation, characterized by a slower pressure drop and a significantly longer pressure holding period, ensures that the heat transferred into the sealed chamber in step S1 is not less than the heat absorbed by the vaporization of moisture within the sealed chamber, thereby maintaining the temperature of the internal components above the freezing temperature of water. Physically, the significant loss of latent heat of vaporization is the direct cause of localized rapid cooling. Adaptively slowing the vacuuming rate or extending the pressure holding time provides sufficient time for heat transfer in step S1, ensuring that external heat can be fully transferred to the internal components to compensate for the heat absorbed during evaporation. This physically eliminates the conditions for residual water vapor to solidify and freeze.

[0026] During the vacuuming operation, the moisture content in the gas extracted from the sealed chamber is monitored in real time. In practice, a high-precision dew point meter can be connected in parallel to the front end of the vacuum pump's extraction line. The preset drying standard is: the moisture content detected during two consecutive vacuuming operations is lower than a first preset threshold, and the difference is less than a second preset threshold (for example, the first preset threshold is set to dew point -45℃, and the second preset threshold is 2℃). If the preset drying standard is not met, the pressure reduction and pressure holding stages continue to alternate; when the moisture content reaches the preset drying standard, the vacuuming operation, the gas injection operation, and the continuous heating of the sealed chamber are stopped.

[0027] Step S3: Inflate the sealed gas chamber with environmentally friendly insulating gas until the pressure inside the sealed gas chamber reaches the preset working pressure. Based on the nameplate parameters of environmentally friendly gas-filled cabinets in actual engineering projects, the preset working pressure is typically set to an absolute pressure of 0.12 MPa to 0.16 MPa, specifically 0.14 MPa. For practical engineering applications, the environmentally friendly insulating gas is preferably dry compressed air; alternatively, the environmentally friendly insulating gas can also be selected from any one of nitrogen, a mixture of fluorinated nitric acid and carbon dioxide, or a mixture of fluorinated nitric acid and nitrogen.

[0028] To avoid localized extreme cold caused by adiabatic expansion during rapid gas filling, which could lead to low-temperature embrittlement and loss of elasticity of the sealing rubber ring, the filling of the sealed gas chamber with environmentally friendly insulating gas includes dividing the filling process into multiple filling stages with progressively decreasing filling rates (for example, specifically divided into three stages: high-flow-rate high-speed filling, medium-flow-rate stable filling, and low-flow-rate low-speed fine-tuning). During the execution of any of the filling stages, the temperature change rate at the sealing interface of the sealed gas chamber is acquired. When the absolute value of the temperature change rate exceeds a preset temperature change rate threshold, the current filling stage is paused until the temperature at the sealing interface rises back to a preset safe temperature before resuming the paused filling stage. For example, if a rapid temperature drop is detected at a flange interface (e.g., the absolute value of the temperature change rate exceeds a preset temperature change rate threshold of 5°C / min), filling is immediately paused until the temperature at that location naturally rises back to a preset safe temperature above 0°C before resuming filling, thus balancing filling efficiency with the intrinsic safety of the sealing material.

[0029] Following S3, the process further includes S4: applying mechanical vibration to the environmentally friendly gas-filled cabinet, and during this process, detecting the leakage rate at the sealing joint of the sealed gas chamber shell. In specific implementation, an external low-frequency vibrator is used to apply mechanical vibration to the environmentally friendly gas-filled cabinet with a frequency of 10Hz to 30Hz (e.g., preferably 20Hz) and an amplitude of 0.1mm to 0.5mm (e.g., preferably 0.3mm) to simulate the resonance conditions of power grid operation and transportation bumps. While maintaining this mechanical vibration, a high-precision gas sniffer is used to perform mobile scanning of the sealing joints of the sealed gas chamber shell, such as the flange interface, valve connection, and metal welds. If the detected annual leakage rate is extremely low (e.g., below 0.1% / year), the sealing performance of the environmentally friendly gas-filled cabinet is deemed qualified, thereby eliminating the safety hazard of insulation failure during long-term operation of the equipment.

Claims

1. A method for filling an environmentally friendly gas-filled cabinet with gas, the environmentally friendly gas-filled cabinet comprising a sealed gas chamber for encapsulating internal components, characterized in that, The gas filling method includes the following steps: S1. The sealed air chamber is continuously heated to bring the temperature conditions for moisture desorption inside the sealed air chamber to a level that is maintained. S2. Alternately perform vacuuming and gas injection operations inside the sealed gas chamber; Specifically, during the vacuuming operation, the operation is divided into multiple alternating pressure reduction and pressure holding phases until the absolute pressure in the sealed chamber drops to a first preset pressure and is maintained for a first preset duration. During any of the pressure reduction phases, real-time temperature data at the internal components is acquired. When the real-time temperature data drops to a preset temperature, the pressure reduction rate of the current pressure reduction phase is reduced, and / or the holding time of the next adjacent pressure holding phase is extended, so that the heat transferred into the sealed chamber in S1 is not less than the heat absorbed by the vaporization of moisture in the sealed chamber, thereby maintaining the temperature at the internal components above the water freezing temperature. The preset temperature is higher than the freezing temperature of the water; When performing the gas injection operation, dry gas is injected into the sealed gas chamber until the absolute pressure in the sealed gas chamber rises to the second preset pressure and is maintained for the second preset duration; The first preset pressure is less than the second preset pressure; During the vacuuming operation, the moisture content in the gas extracted from the sealed chamber is monitored in real time. When the moisture content reaches the preset drying standard, the vacuuming operation, the gas injection operation, and the continuous heating of the sealed chamber are stopped. S3. Inject environmentally friendly insulating gas into the sealed gas chamber until the pressure inside the sealed gas chamber reaches the preset working pressure.

2. The gas filling method according to claim 1, characterized in that, The preset drying standard is: The micro-moisture content detected during the vacuuming operation was lower than the first preset threshold and the difference was less than the second preset threshold in two consecutive tests.

3. The gas filling method according to claim 1, characterized in that, The temperature conditions for moisture desorption are as follows: The temperature inside the sealed air chamber is between 60°C and 70°C.

4. The gas filling method according to claim 1, characterized in that, The preset temperature is set to 1℃~5℃.

5. The gas filling method according to claim 1, characterized in that, The first preset pressure is 30Pa~70Pa; the second preset pressure is 0.11MPa~0.15MPa.

6. The gas filling method according to claim 1, characterized in that, The process of filling the sealed gas chamber with environmentally friendly insulating gas includes: The process of filling with environmentally friendly insulating gas is divided into multiple filling stages with successively decreasing filling rates; During the execution of any of the filling stages, the temperature change rate at the sealing joint of the sealed gas chamber is obtained; when the absolute value of the temperature change rate is greater than a preset temperature change rate threshold, the current filling stage is paused until the temperature at the sealing joint of the shell rises back to a preset safe temperature, and then the paused filling stage is resumed.

7. The gas filling method according to claim 1, characterized in that, Following S3, the following also includes: S4. Apply mechanical vibration to the environmentally friendly gas-filled cabinet, and during this process, detect the leakage rate at the sealing joint of the sealed gas chamber shell.

8. The gas filling method according to claim 1, characterized in that, The environmentally friendly insulating gas is selected from any one of the following: dry compressed air, nitrogen, a mixture of fluorinated nitric acid and carbon dioxide, or a mixture of fluorinated nitric acid and nitrogen.

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