An SF6 purification process utilizing gas hydrate formation developed for electric power industry

A sulfur hexafluoride (SF6) separation/purification process utilizing gas hydrate formation has been known for a while but its application to industrial use has not been attempted. A system with this process was developed for used SF6 gas from heavy electric equipment. SF6 hydrate formation equilibrium data and SF6 hydrate formation rate data were collected with a batch reactor. The data were used to design a continuous SF6 separation/purification reactor utilizing hydrate formation and dissociation process. The reactor was comprised of a SF6 formation part, a dissociation part, a dryer to remove the moisture in purified SF6, and a compression/refilling part. This reactor was used to separate/purify recovered SF6 from heavy electric equipment to purify 81 vol% SF6 to 93 vol% SF6. Even though the highest purity of SF6 obtainable from the SF6 separation/purification reactor was lower than those from commercial reactors using other separation/purification processes, it can be used to concentrate low grade SF6 gas whose purity is too low to be processed directly with commercial reactors using liquefaction/cryogenic technologies.