Status of SF6 separation/refining technology development for electric industry in Korea

KEPCO (Korea Electric Power Corporation) possesses and regularly maintains SF6 filled power distribution facilities containing SF6 gas from several liters up to several tens of liters. During the replacement of expired facilities, waste SF6 gas is produced. And some facilities are refilled with SF6. Since SF6 is one of the most potent greenhouse gases, KEPCO is developing technologies to recover and separate/refine SF6 from expired power distribution facilities and reuse it to reduce SF6 release and maintenance cost. A hybrid system of liquefaction and PSA (Pressure Swing Adsorption) had been developed, even though its refinement rate was too slow to use practically. The technology developed next was liquefaction technology, which has been under test. Its process is relatively simple and its manufacturing cost is low, but its refinement quality is expected to be low. A cryogenic freezing technology freezes SF6 for refinement. Even though the technology is energy-intensive, it can produce high purity SF6 and can be easily scale up, which make the technology suitable to be commercialized. Currently, this technology is being optimized. The last technology under development is a hydrate technology, which utilized SF6-hydrate formation. Its advantage is less energy-intensive and it is considered to be suitable for refining relatively low quality SF6 (>70%).