SF6 Gas Recovery and Purification Unit Operating Guide
As global regulations on greenhouse gas emissions become increasingly stringent, SF₆ gas recovery and purification units have become indispensable key equipment in the power industry. As a leading enterprise in the field of high-voltage testing equipment in China, Goldhome manufactures the HMLH series of SF₆ gas recovery and purification units. Thanks to their high-efficiency recovery, deep purification, and safe and reliable performance, these units are widely used in the maintenance and repair of equipment such as GIS switchgear and circuit breakers. This document provides a detailed introduction to the operation of the Goldhome SF6 Gas Recovery and Purification Unit.
Product Overview and Working Principle
The Goldhome SF6 gas recovery and purification unit operates on the principle of refrigerated liquefaction, integrating functions such as recovery, charging/discharging, purification, vacuum extraction, storage, and cylinder filling. Through the suction and compression action of the compressor, the unit draws in and compresses the SF6 gas from electrical equipment, simultaneously utilizing the low evaporation temperature of R22 refrigerant to cool, liquefy, and store the gas. The purification process is performed simultaneously during recovery and charging/discharging. The system's three built-in oil separators and desiccant filters effectively remove oil and moisture from the gas, ensuring the purity of the SF6 gas.
Detailed Operating Procedures
Pre-Operation Preparation
Conduct a thorough safety inspection before use: Verify that the equipment is properly grounded, that there are no leaks in the piping, and that the power supply is stable at 380V ±10% three-phase, five-wire AC. Connect the recovery unit to the gas chamber port of the electrical equipment using a dedicated hose, ensuring a secure seal. If the gas is severely contaminated, it is recommended to test for impurity types in advance.
Step 1: Vacuum Evacuation
Before starting the vacuum pump, inspect the piping connections and confirm that the pressure gauge of the system to be evacuated reads zero or lower. Use the unit's vacuum pump to evacuate SF6 electrical equipment and connecting piping. The unit's ultimate vacuum is ≤10 Pa; it takes less than one hour to evacuate a 1 m³ volume of SF6 gas with an initial pressure of 0.1 MPa to 133 Pa. An electromagnetic vacuum-sealing valve is installed at the vacuum pump inlet; it automatically seals the system when the pump stops to prevent oil backflow contamination.
Step 2: Gas Recovery
It is recommended to start the refrigeration compressor one hour in advance to ensure suitable ambient temperature. Start the compressor to draw in and compress the SF6 gas from the electrical equipment at a certain pressure, then cool and liquefy it for storage. The Goldhome can recover residual pressure from GIS to 50 kPa (absolute pressure). During recovery, the liquid level in the storage container can be observed through a sight glass; it is recommended that the liquid level not exceed two-thirds of the sight glass.
Step 3: Purification
The recovered gas passes through a molecular sieve dryer to remove moisture and an oil separator to remove oil. For SF6 gas with a moisture content below 1,000 ppm, the Goldhome unit achieves a moisture content of <60 ppm (by weight) and an oil content of <10 ppm (by weight) after a single recovery and purification cycle. The filter is equipped with a heating regeneration system that allows for regeneration under vacuum conditions, enabling the molecular sieve to be reused repeatedly.
Step 4: Gas Charging and Cylinder Filling
During gas charging, utilize either pressure differential or a compressor to transfer SF6 from the unit's storage vessel into electrical equipment until the required operating pressure is reached. During cylinder filling, utilize the refrigeration properties to directly fill cylinders with liquefied SF6. Note that a portion of SF6 liquid should be reserved inside the cylinder to prevent filling an empty cylinder.
Step 5: End of Operation
Close all valves, disconnect the piping, and record the recovered gas volume, purity, and processing data. The control panel of the Guodian Huamei unit integrates the electrical control cabinet, operating valves, and monitoring instruments, and is equipped with process indicators, making operation convenient and intuitive.
Safety Protections and Precautions
The Goldhome unit is equipped with reliable safety protection devices: a high-pressure controller is installed at the compressor discharge port to automatically shut down the system in case of overpressure; a safety valve is installed on the storage tank to automatically vent excess pressure. During operation, wear a gas mask, goggles, and gloves to prevent poisoning from SF6 decomposition products. Control the pressure during recovery to prevent air ingress, and regularly replace filters, check compressor oil, and inspect seals.
