The SF6 gas recovery device is a crucial specialized equipment in the power industry (especially in substations that use GIS (Gas Insulated Switchgear) and SF6 circuit breakers), with its core function being to safely, efficiently, and environmentally friendly processing of SF6 gas.
I. Core Functions and Roles
A set of SF6 gas recovery devices typically integrates one or more of the following functions to cover the entire lifecycle processing requirements of SF6 gas:
Recovery (Suction): Extracting SF6 gas from electrical equipment such as circuit breakers and GIS compartments, which is the core and fundamental function of the device.
Purification Treatment: Removing impurities from SF6 gas during the recovery process, including moisture, air (CF4, N2, etc.), and decomposition products (SO2, HF, etc.).
Liquefaction Storage: Compressing and cooling the purified pure SF6 gas to liquefy it and store it in the built-in storage tank, significantly reducing the volume of gas storage.
Precise Filling: Vaporizing the stored liquid SF6 gas and precisely filling it into the target electrical equipment to meet the gas consumption requirements of the equipment.
Compression and Boosting: Compressing the SF6 gas in the electrical equipment to reach the rated pressure required for the equipment operation.
Vacuuming: After gas recovery or before filling with new gas, evacuating the internal components and connection pipelines of the electrical equipment to completely remove residual air and moisture.
II. Main Subsystem Components
The SF6 gas recovery device is composed of multiple functional subsystems to ensure stable and reliable overall operation:
Recovery Compressor: The core power component, responsible for extracting gaseous SF6 from the equipment and compressing it, usually a dedicated compressor suitable for liquidation gas processing.
Vacuum Pump: Used for evacuating the system and electrical equipment, creating a negative pressure environment, and removing moisture and residual air.
Purification System:
Filter: Containing dust filters, molecular sieves, etc., specifically for removing moisture and decomposition products from the gas;
Oil Separator: Separating oil that may be brought in during the operation of the compressor to avoid contaminating the SF6 gas.
Condensation and Liquefaction Unit: Cooling the compressed high-pressure SF6 gas through a refrigeration system to convert it into a liquid state for easy storage.
Storage Tank: Specifically for storing the liquefied pure SF6 gas to ensure the safety of gas storage.
Pressure and Vacuum Gauges: Real-time monitoring of the pressure values and vacuum degree of each key node of the system to ensure traceability of the operating status.
Control System: Modern devices mostly use PLC control to achieve automated operation, safety protection, and operation data recording functions.
Connection Pipelines and Valves: Forming a complete sealed gas path system to ensure smooth gas transmission and no leakage.
III. Key Parameters for Selection
When selecting an SF6 gas recovery device, the following core parameters need to be focused on, matching the actual application requirements:
Recovery Rate: The mass of SF6 gas that can be recovered per unit time (kg), directly determining the working efficiency. Large GIS equipment should preferentially choose models with high recovery rates.
Final Vacuum Degree: The core indicator for measuring the vacuum extraction capability, the higher the value (the better the vacuum), usually requiring a vacuum degree of < 10 Pa or higher standards.
Post-Recovery Residual Pressure: The lower pressure that the SF6 gas in the equipment can be extracted, the lower the residual pressure, indicating a more thorough gas recovery and reducing waste and pollution.
Storage Tank Capacity: Determines the total amount of SF6 gas that can be processed in a single operation, avoiding the impact on work continuity during intermediate gas transfer.
Gas Purification Indicators:
Dew Point: The moisture content of the treated gas, usually requiring ≤ -40°C, some scenarios require ≤ -50°C;
Oil Content: Needs to be controlled at < 1 ppm;
Purity: The purity of the treated SF6 gas needs to be ≥ 99.9%. Automation level: Whether it supports one-click operation, automatic shutdown, and function of recording operation data, etc., to enhance operational convenience and safety.
Mobility and power supply: The ease of transporting the equipment (such as whether it has wheels, or is designed for portability), as well as the power supply requirements at the site (380V/220V)